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Sample records for na biomasa vo

  1. Phase composition and equilibria of the system FeVO4-CrVO4-AlVO4-NaVO3

    International Nuclear Information System (INIS)

    The methods of physicochemical and X-ray diffraction analysis have been used to carry out triangulation of the three systems, containing FeVO4, CrVO4, AlVO4 and NaVO3, and tetrahedration of the FeVO4-CrVO4-AlVO4-NaVO3 system. Formation of the area of continuous complex solution between the NaFeV2O7, NaCrV2O7 and NaAlV2O7 is shown

  2. Systems Li3VO4(Na3VO4)-Pb3(VO4)2-V2O5

    International Nuclear Information System (INIS)

    Phase composition of Li3VO4-Pb3(VO4)2-V2O5 and Na3VO4-Pb3(VO4)-V2O5 systems is investigated. In the first system double vanadates are not produced, in the second one NaPbVO4, NaPb4(VO4)3 and Na5PbV3O11 compounds are identified. System phase ratio diagrams, related to subsolidus region (450-500 deg C), are plotted. 9 refs., 3 figs

  3. Pyroxene-type (K,Na,Li)VO3 solid solutions

    International Nuclear Information System (INIS)

    Phase relations in the system were studied between 600 degrees and 350 degrees C. All three end members have the pyroxene-type structure. Both LiVO3 and NaVO3 are monoclinic, whereas KVO3 takes the orthorhombic symmetry. At 360 degrees C, the join LiVO3-NaVO3 is characterized by two series of pyroxene-type solid solutions: NaVO3-(Na0.44Li0.56)VO3 and LiVO3-(Na0.16Li0.84)-VO3 · (K0.5Na0.5)VO3 and (K0.5Li0.5)VO3 are two other stable phases at 360 degrees C. The pyroxene-type (K0.5Na0.5)VO3 has a range of solid solution from (K0.6Na0.4)VO3 to (K0.4Na0.6)VO3 along the join and extends into the ternary field with a maximum of 13 mol% LiVO3 · (K0.5Li0.5)VO3 has no detectable range of solid solution, and its x-ray powder diffraction data cannot be indexed based upon either the monoclinic or the orthorhombic unit cell

  4. Solubility in the NH4Cl-NaVO3-NH4VO3-NaCl-H2O system

    International Nuclear Information System (INIS)

    Solubility of salts in reciprocal system NH4Cl-NaVO3-NH4VO3-NaCl-H2O at 20 deg C was studied by the method of isothermal saturation using the chemical and X-ray phase analyses, the system solubility diagram being plotted. The diagram contains separate fields of salts crystallization, limited by five branches, and two ternary points. The ratio of the salts crystallization surface areas is approximately equal to 90000:10000:3:1 (NH4VO3:NaVO3:NaCl:NH4Cl), i.e. above 90% of crystallization field is occupied by ammonium vanadate, featuring the lowest solubility

  5. Liquidus of the Na parallel WO4, Cl, I (VO3, CO3) system

    International Nuclear Information System (INIS)

    DTA method is used to study Na parallel WO4, Cl, I(VO3, CO3) mutual systems. Congruently melting Na3WO4Cl compound permitted to triangulate systems into secondary triangles with ternary eutectic points. The fusibility diagrams for three ternary systems are presented as intersection of three second-order surfaces. Coordinates of some nonvariant points are refined by projection-thermographic method

  6. AC conductivity and dielectric behavior of polyaniline/sodium metavenadate (PANI/NaVO3) composites

    International Nuclear Information System (INIS)

    The conducting polyaniline/sodium metavenadate (PANI/NaVO3) composites were synthesized by single step in situ polymerization technique by placing finely grinded powder of NaVO3 during the polymerization of aniline. The formation of mixed phases of the polymer together with the conducting emeraldine salt phase was confirmed by spectroscopic techniques like FTIR. SEM images indicated a systematic morphological variation of particles aggregated in the composite matrix as compared to the pristine PANI. AC conductivity and dielectric behavior of these composites were investigated in the frequency range 50 Hz to 5 MHz. It is found that AC conductivity obeyed the power law index and the variation of conductivity with wt% of NaVO3 could be related to conductivity relaxation phenomenon. These composites have shown high dielectric constant, which is related to polarization. It is seen that both dielectric constant and dielectric loss decrease with increase in frequency. Variations in measured parameters of AC response with increasing frequency of these composites are found to follow systematic trends that are similar to those observed with temperature and doping.

  7. Thermogravimetric study of the 800 degree C reaction of zirconia stabilizing oxides with SO3-NaVO3

    International Nuclear Information System (INIS)

    In this paper a thermogravimetric study is made of the reaction of the zirconia stabilizing oxides, In2O3, Sc2O3, Y2O3, and MgO, with molten NaVO3 at 800 degrees C under SO3 partial pressures of 10+2 to 10- 3 Pa. The melt composition is determined by: 2NaVO3 + SO3 right-reversible V2O5 + Na2SO4. No reaction of In2O3 was found at SO3 partial pressures up to 5 x 10+1 Pa where the reaction, In2O3 + V2O5 = 2InVO4, commenced. Reaction of Sc2O3 occurred at about 5 x 10- 1 Pa of SO3 with ScVO4 formed. Reaction of Y2O3 and MgO with the NaVO3 melt began, on the other hand, at SO3 partial pressures too low to be measured (- 3 Pa). In2O3 and (Sc)2O3 are thus potentially superior to Y2O3 and MgO as stabilizers for hot corrosion resistant zirconia thermal barrier coatings. Certain other information concerning the thermochemistry of the SO3-NaVO3 system was also revealed

  8. Neutron and X-ray diffraction studies on the high temperature phase of Mn{sub 3}(VO{sub 4}){sub 2}, the new isostructural compound NaMn{sub 4}(VO{sub 4}){sub 3} and their mixed crystals Na{sub x}Mn{sub 4.5-x/2}(VO{sub 4}){sub 3} (0{<=}x{<=}1)

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, Oliver [Universitaet des Saarlandes, Institut fuer Anorganische und Analytische Chemie und Radiochemie, Am Markt, Zeile 5, 66125 Saarbruecken (Germany); Haberkorn, Robert [Universitaet des Saarlandes, Anorganische Festkoerperchemie, Am Markt, Zeile 3, 66125 Saarbruecken (Germany); Springborg, Michael [Universitaet des Saarlandes, Physikalische und Theoretische Chemie, Campus B2 2, 66123 Saarbruecken (Germany); Beck, Horst Philipp, E-mail: hp.beck@mx.uni-saarland.de [Universitaet des Saarlandes, Institut fuer Anorganische und Analytische Chemie und Radiochemie, Am Markt, Zeile 5, 66125 Saarbruecken (Germany)

    2012-10-15

    This paper presents a detailed structure analysis (combined Rietveld analysis of X-ray and neutron powder diffraction data as well as quantum mechanical calculations) of the high temperature phase of Mn{sub 3}(VO{sub 4}){sub 2} (space group I4 Macron 2d). Special attention is directed to the analysis of the local coordination around Mn{sup 2+} ions or vacancies within a stella quadrangula configuration of anions. Furthermore, the new compound NaMn{sub 4}(VO{sub 4}){sub 3} is described as well as a range of mixed crystals between NaMn{sub 4}(VO{sub 4}){sub 3} and Mn{sub 3}(VO{sub 4}){sub 2} (described by the formula Na{sub x}Mn{sub 4.5-x/2}(VO{sub 4}){sub 3}, 0{<=}x{<=}1) which were synthesized by a solid state route. All compounds were shown to be isostructural to the high temperature phase Mn{sub 3}(VO{sub 4}){sub 2}. - Graphical abstract: The crystal structure of the new compound NaMn{sub 4}(VO{sub 4}){sub 3}. Highlights: Black-Right-Pointing-Pointer We present neutron and X-ray diffraction studies on high temperature-Mn{sub 3}(VO{sub 4}){sub 2}. Black-Right-Pointing-Pointer Structural details of partly filled stellae quadrangulae positions are discussed. Black-Right-Pointing-Pointer Refined structural parameters and theoretical calculations are compared. Black-Right-Pointing-Pointer We investigate the mixed crystal system Mn{sub 3}(VO{sub 4}){sub 2}-NaMn{sub 4}(VO{sub 4}){sub 3}.

  9. Pressure-induced amorphization of NaVO/sub 3 at room temperature and its re-crystallization

    International Nuclear Information System (INIS)

    Pressure-induced amorphization is the subject of intense study for the past few years because of its importance in material science and in solid state physics. We reported a crystalline-amorphous phase transition at ca 60kbar in NaVO1/3, which is the lowest pressure for such transitions in ionic crystals. The transition is marked by the sudden appearance of very broad bands at the 800 and 350 cm/sup -1 regions. The amorphization includes the complete breaking up of the infinite chains of corner-linked tetrahedral VO/sub 4, most likely into VO/sup -/sub 3. On decompression, the amorphous phase transforms to another phase, probably also amorphous at ca 40 kbar. It reverts to the stable ambient condition ?-phase upon heating. Here we report on the details of the transtitional region and the re-linking of the VO/sub 4 chains upon heating. (authors)

  10. Neutron and X-ray diffraction studies on the high temperature phase of Mn3(VO4)2, the new isostructural compound NaMn4(VO4)3 and their mixed crystals NaxMn4.5?x/2(VO4)3 (0?x?1)

    International Nuclear Information System (INIS)

    This paper presents a detailed structure analysis (combined Rietveld analysis of X-ray and neutron powder diffraction data as well as quantum mechanical calculations) of the high temperature phase of Mn3(VO4)2 (space group I4¯2d). Special attention is directed to the analysis of the local coordination around Mn2+ ions or vacancies within a stella quadrangula configuration of anions. Furthermore, the new compound NaMn4(VO4)3 is described as well as a range of mixed crystals between NaMn4(VO4)3 and Mn3(VO4)2 (described by the formula NaxMn4.5-x/2(VO4)3, 0?x?1) which were synthesized by a solid state route. All compounds were shown to be isostructural to the high temperature phase Mn3(VO4)2. - Graphical abstract: The crystal structure of the new compound NaMn4(VO4)3. Highlights: ? We present neutron and X-ray diffraction studies on high temperature-Mn3(VO4)2. ? Structural details of partly filled stellae quadrangulae positions are discussed. ? Refined structural parameters and theoretical calculations are compared. ? We investigate the mixed crystal system Mn3(VO4)2–NaMn4(VO4)3.

  11. Neutron and X-ray diffraction studies on the high temperature phase of Mn3(VO4)2, the new isostructural compound NaMn4(VO4)3 and their mixed crystals NaxMn4.5-x/2(VO4)3 (0?x?1)

    Science.gov (United States)

    Clemens, Oliver; Haberkorn, Robert; Springborg, Michael; Beck, Horst Philipp

    2012-10-01

    This paper presents a detailed structure analysis (combined Rietveld analysis of X-ray and neutron powder diffraction data as well as quantum mechanical calculations) of the high temperature phase of Mn3(VO4)2 (space group I4¯2d). Special attention is directed to the analysis of the local coordination around Mn2+ ions or vacancies within a stella quadrangula configuration of anions. Furthermore, the new compound NaMn4(VO4)3 is described as well as a range of mixed crystals between NaMn4(VO4)3 and Mn3(VO4)2 (described by the formula NaxMn4.5-x/2(VO4)3, 0?x?1) which were synthesized by a solid state route. All compounds were shown to be isostructural to the high temperature phase Mn3(VO4)2.

  12. Relação entre modificações cinemáticas da corrida e o tempo limite na vVO2máx / Relationship between running kinematic changes and time limit at vVO2max

    Scientific Electronic Library Online (English)

    Leonardo, De Lucca; Sebastião Iberes Lopes, Melo.

    Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in portuguese A corrida realizada na velocidade do consumo máximo de oxigênio (vVO2máx) pode ocasionar modificações nos parâmetros cinemáticos e assim, aumentar o custo energético ao longo do tempo. O objetivo do presente estudo foi analisar características cinemáticas da articulação do tornozelo e joelho durante [...] a corrida na vVO2máx e a relação entre modificações cinemáticas e o tempo limite na vVO2máx(Tlim). Onze voluntários ativos fisicamente foram submetidos a um teste incremental de corrida para determinar a vVO2máx e posteriormente, a um teste de velocidade constante na vVO2máx. As variáveis cinemáticas foram adquiridas através de filmagem bidimensional a 210Hz no plano sagital esquerdo, no estágio inicial e final da corrida. De todas as variáveis angulares analisadas, a máxima plantiflexão no balanço (p Abstract in english Exhaustive running at maximal oxygen uptake velocity (vVO2max) can alter running kinematic parameters and increase energy cost along the time. The aims of the present study were to compare characteristics of ankle and knee kinematics during running at vVO2max and to verify the relationship between c [...] hanges in kinematic variables and time limit (Tlim). Eleven male volunteers, recreational players of team sports, performed an incremental running test until volitional exhaustion to determine vVO2max and a constant velocity test at vVO2max. Subjects were filmed continuously from the left sagittal plane at 210 Hz for further kinematic analysis. The maximal plantar flexion during swing (p

  13. Cinética do VO2 durante o exercício realizado na potência crítica em ciclistas e indivíduos não-treinados no ciclismo / VO2 Kinetics during exercise performed at critical power in cyclists and untrained individuals

    Scientific Electronic Library Online (English)

    Renato Aparecido Corrêa, Caritá; Camila Coelho, Greco; Dalton Müller, Pessôa Filho.

    2013-06-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo foi analisar a cinética do consumo de oxigênio (VO2) na potência crítica (PC), em indivíduos com diferentes níveis de aptidão aeróbia no ciclismo. Seis ciclistas treinados (GT) e sete indivíduos não-treinados (GNT) realizaram os seguintes protocolos em cicloergômetro: (a) progressivo até [...] a exaustão para determinação do VO2max e sua respectiva intensidade (IVO2max); (b) três testes em cargas constantes até a exaustão a 95-110%IVO2max para determinação da PC; e (c) um teste em carga constante até a exaustão a 100%PC. No exercício a 100%PC, o componente lento expresso em valor absoluto (GT: 342,4±165,8 ml.min-1 vs. GNT: 571,3±170,1 ml.min-1) e relativo ao aumento do VO2 em exercício (GT: 10,0±4,6% vs. GNT: 26,6±7,3%) foram menores para GT. O VO2 ao final do exercício (GT: 89,8±8,4%VO2max vs. GNT: 97,4±2,8%VO2max) foi significativamente menor no grupo GT (? = 0,045), sendo similar ao VO2max no grupo GNT. Portanto, o nível de aptidão aeróbia pode influenciar as respostas do VO2 ao exercício em PC. Abstract in english The objective was to analyze the oxygen uptake (VO2) kinetics during exercise performed at critical power (CP) in subjects with different aerobic status in cycling. Six trained cyclists (GT) and seven non-trained subjects (GNT) underwent to the following protocols in cyclergometer: (a) incremental t [...] o exhaustion to determine VO2max and its respective workload (IVO2max); b) three square-wave tests to exhaustion at 95-110% IVO2max to determine CP, and; (c) one square-wave test to exhaustion at 100%CP. During the exercise at CP the slow component expressed as absolute value (GT: 342.4±165.8 ml.min-1 vs. GNT: 571.3±170.1 ml.min-1) and as the relative contribution to the increase of VO2 during exercise (GT: 10.0±4.6% vs. GNT: 26.6±7.3%) were lower for trained subjects. The VO2 at the end of the exercise at PC (GT: 89.8±8.4%VO2max vs. GNT: 97.4±2.8%VO2max) was significantly lower in GT (? = 0.045), and similar to VO2max in GNT. Therefore, the aerobic level might influence the VO2 responses to exercise at PC.

  14. Hot corrosion behaviour of Fe-Al based intermetallic in molten NaVO3 salt

    International Nuclear Information System (INIS)

    The hot corrosion of sprayed Fe-40 (at.%)Al intermetallic alloy with additions of boron and alumina whiskers in molten NaVO3 at 700 deg. C has been evaluated by potentiodynamic polarization curves and electrochemical impedance spectroscopy, EIS, techniques. For short exposure times, the corrosion mechanism under these conditions was observed to be controlled by an activation process, whereas for longer exposure times, the corrosion process was under diffusion control due to the growing of an Al2O3 oxide scale, which made the diffusion of both reducing and oxidizing species through the scale to the alloy or scale surfaces more difficult. Equivalent electric model used to simulate the EIS data showed that a finite length Warburg diffusion could properly characterize the diffusion process, which confirmed the formation of a compact corrosion product scales containing rich aluminium oxide. Thus, the corrosion process was under diffusion control of aggressive ions through the formed scale. The electrochemical study was complemented by scanning electronic microscopy characterization and micro chemical analysis.

  15. Graphene quantum dots coated VO2 arrays for highly durable electrodes for Li and Na ion batteries.

    Science.gov (United States)

    Chao, Dongliang; Zhu, Changrong; Xia, Xinhui; Liu, Jilei; Zhang, Xiao; Wang, Jin; Liang, Pei; Lin, Jianyi; Zhang, Hua; Shen, Ze Xiang; Fan, Hong Jin

    2015-01-14

    Nanoscale surface engineering is playing important role in enhancing the performance of battery electrode. VO2 is one of high-capacity but less-stable materials and has been used mostly in the form of powders for Li-ion battery cathode with mediocre performance. In this work, we design a new type of binder-free cathode by bottom-up growth of biface VO2 arrays directly on a graphene network for both high-performance Li-ion and Na-ion battery cathodes. More importantly, graphene quantum dots (GQDs) are coated onto the VO2 surfaces as a highly efficient surface "sensitizer" and protection to further boost the electrochemical properties. The integrated electrodes deliver a Na storage capacity of 306 mAh/g at 100 mA/g, and a capacity of more than 110 mAh/g after 1500 cycles at 18 A/g. Our result on Na-ion battery may pave the way to next generation postlithium batteries. PMID:25531798

  16. A study of optical properties of Sm3+ ions in ?-Na3Y(VO4)2 single crystals

    International Nuclear Information System (INIS)

    Single crystals of ?-Sm3+:Na3Y(VO4)2 have been grown by the flux growth method. The absorption (300 K) fluorescence (4.2 and 300 K) and excitation (7 and 300 K) spectra as well as the fluorescence dynamics of the Sm3+-doped title crystals are presented and analyzed in detail. The energy transfer between Sm3+–Sm3+ as well as from VO43? to Sm3+ were studied in detail. A Judd–Ofelt intensity analysis of the absorption (300 K) spectrum has been applied for determination of ?? parameters which in turn have been used in calculation of the radiative transition probability factor (A), fluorescence branching ratios (?), natural (radiative) lifetime of the 4G(4)5/2 level of Sm3+ and emission cross-section (?em). For the first time very large lifetimes of the Sm3+ fluorescence level have been observed. -- Highlights: • Single crystals of Sm3+-doped ?-Na3Y(VO4)2 have been grown by the flux growth method. • The room and low-temperature spectroscopic properties of the single crystals were investigated. • The decay time of the fluorescence level are larger than those earlier reported for some Sm3+ doped vanadate materials. • Sm-doped ?-NYV crystal is a new promising luminescence materials

  17. Efeitos do estado e especificidade do treinamento aeróbio na relação %VO2max versus %FCmax durante o ciclismo / Effects of the state and specificity of aerobic training on the %VO2max versus %HRmax ratio during cycling

    Scientific Electronic Library Online (English)

    Fabrizio, Caputo; Camila Coelho, Greco; Benedito Sérgio, Denadai.

    2005-01-01

    Full Text Available OBJETIVO: Determinar os efeitos do estado e especificidade de treinamento aeróbio na relação entre o percentual do consumo máximo de oxigênio (%VO2max) e o percentual da frequência cardíaca máxima (%FCmax) durante o exercício incremental realizado no cicloergômetro. MÉTODOS: Sete corredores, 9 cicli [...] stas, 11 triatletas e 12 sedentários, todos do sexo masculino e aparentemente saudáveis, foram submetidos a um teste incremental até a exaustão no cicloergômetro. Regressões lineares entre %VO2max e %FCmax foram determinadas para cada indivíduo. Com base nessas regressões, foram calculados %FCmax correspondentes a determinados %VO2max (50, 60, 70, 80 e 90%) de cada participante. RESULTADOS: Não foram encontradas diferenças significantes entre todos os grupos nos %FCmax para cada um dos %VO2max avaliados. Analisando-se os voluntários como um único grupo, as médias dos %FCmax correspondentes a 50, 60, 70, 80 e 90% %VO2max foram 67, 73, 80, 87, e 93%, respectivamente. CONCLUSÃO: Nos grupos analisados, a relação entre o %VO2max e %FCmax durante o exercício incremental no ciclismo não é dependente do estado e especificidade do treinamento aeróbio. Abstract in english OBJECTIVE: To determine the effects of the status and specificity of exercise training in the ratio between maximum oxygen consumption (%VO2max) and the percentage of maximal heart rate (%HRmax) during incremental exercise on a cycle ergometer. METHODS: Seven runners, 9 cyclists, 11 triathletes, and [...] 12 sedentary individuals, all male and apparently healthy, underwent exhaustive incremental exercise on cycle ergometers. Linear regressions between %VO2max x %HRmax were determined for each individual. Based on these regressions, %HRmax was assessed corresponding to a determined %VO2max (50, 60, 70, 80, and 90%) from each participant. RESULTS: Significant differences were not found between the groups in %HRmax for each of the %VO2max assessed. Analyzing the volunteers as a single group, the average of the corresponding %HRmax to 50, 60, 70, 80, and 90% %VO2max were 67, 73, 80, 87, and 93%, respectively. CONCLUSION: The ratio between %VO2max and %HRmax in the groups assessed during incremental exercise on the bicycle is not dependent on the status and specificity of aerobic exercise training.

  18. A detailed study of the dehydration process in synthetic strelkinite, Na[(UO2)(VO4)] . nH2O (n = 0, 1, 2)

    International Nuclear Information System (INIS)

    Synthetic strelkinite Na[(UO2)(VO4)] . nH2O (n = 0, 1, 2) was systematically investigated by single crystal X-ray diffraction and thermoanalytical methods. The anhydrous form and two hydrates were isolated as single crystals and the structures of these phases solved: Na[(UO2)(VO4)], monoclinic, P21/c, a = 6.0205(1) Aa, b = 8.3365(1) Aa, c = 10.4164(2) Aa, ? = 100.466(2) , V = 514.10(1) Aa3, R1 = 0.0337; Na[(UO2)(VO4)] . H2O, monoclinic, P21/c, a = 7.722(2) Aa, b = 8.512(1) Aa, c = 10.480(4) Aa, ? = 113.18(3) , V = 633.3(3) Aa3, R1 = 0.1658; Na[(UO2)(VO4)] . 2 H2O, monoclinic, P21/n, a = 16.2399(5) Aa, b = 8.2844(2) Aa, c = 10.5011(2) Aa, ? = 97.644(2) , V = 1400.24(6) Aa3, R1 = 0.0776. A possible mechanism of the structural transformation processes during dehydration is proposed based on the structures of the anhydrous phase and the hydrates. (orig.)

  19. EVALUACIÓN DE ÍNDICES DE CONVERSIÓN ENERGÉTICA EN LA PRODUCCIÓN DE GAS COMBUSTIBLE A PARTIR DE BIOMASA / EVALUATION THE RATES OF ENERGY CONVERSIONINTHE PRODUCTIONOFBIOMASSFUELGAS / DETERMINAÇÃOTAXAS DE CONVERSÃO DE ENERGIA NA PRODUÇÃO DE GÁS COMBUSTÍVEL DE BIOMASSA

    Scientific Electronic Library Online (English)

    GERARDO, CABRERA C.; SANTIAGO, MADRIÑAN M.; DEYANIRA, MUÑOZ M..

    2013-12-01

    Full Text Available Os rácios de conversão de energia em gaseificação de biomassa, permite comparações entre gaseificadores e decidir melhor desempenho em um processo industrial. A pesquisa utilizou um tipo de reactor experimental Imbert7 KW, a biomassa de bagaço de cana, madeira e alfarrobeira. Elemental análises fora [...] m realizadas e proximal, e os cálculos de equilíbrio de massa térmica na conversão de taxas volumétricas de energia e de massa (I).Os valores caloríficos de cada gás de biomassa, a uma temperatura mínima de 850 º C e 1050 º C a operação do reactor era óptimo: 3679 kJ / kg de carvão de alfarroba, 4,603 madeira Kj / Kg e 5.009 kJ / kg de bagaço cana. Enquanto as taxas de utilização volumétricasforam: carvão Kj/Nm3 alfarroba 3.509,39, 3.804,39 e 4.847,83 Kj/Nm3 bagaço de madeira Kj/Nm3 cana. Concluímos eficiência gaseificador é de 70%, a taxa de conversão é adequada para estimar a massa calorífica do gás combustível produzido pode ser recuperado em um valor de aquecimento de combustão do gás de síntese é poder cerca de 10% aquecimento a gás e perdas de calor são 30%. Abstract in spanish Los índices de conversión energética en la gasificación de biomasa, permitecomparaciones entregasificadores y obtenerelmejor desempeño enun proceso industrial. Se utilizó un reactor de prueba tipo Imbert de 7 KW y biomasa debagazo de caña de azúcar,madera y árbol de algarrobo. Se realizaron análisis [...] elementales, proximalesy los balances másicos y térmicos en el cálculo de los índices de conversión de energía volumétrica y másica ().Los valores del poder calorífico del gas generado a una temperatura mínima de 850ºC y óptima de 1050ºC, en el reactor fueron: 3679 Kj/Kg de carbón de algarrobo, 4603 Kj/Kg de madera y 5009 Kj/Kg de bagazo de caña. Mientras los índices de aprovechamiento volumétrico fueron: 3509,39 Kj/Nm3decarbón de algarrobo, 3804,39 Kj/Nm3demadera y4847,83 Kj/Nm3debagazo de caña de azúcar. Se concluye que una eficacia del 70% en el gasificador, el índice de conversión es apropiado para estimar el poder calorífico,la masa del gas producido combustible puede ser recuperada en una combustión, el poder calorífico del gas de síntesis es aproximadamente el 10% del poder calorífico de la gasolina y las pérdidas de calor son del 30%. Abstract in english The energy conversion ratios in biomass gasification, allows comparisons between gasifiers and decide best performing one in an industrial process. The research used a test reactor type Imbert 7 KW, biomass sugarcane bagasse, wood and carob tree. Elemental and proximal analyzes were performed and th [...] ermal mass balance calculations involved in the conversion rates volumetric energy and mass (I). The calorific values of each biomass gas at a minimum temperature of 850ºC and 1050ºC optimum reactor operation where: 36779 kJ/kg of coal carob, 4603 kJ/kg of wood and 5009 kJ/kg of bagasse cane. While volumetric utilization rateswhere: 3509.39 of coal carob, 3804.39 Kj/Nm3 wood and 4847.83 Kj/Nm3 sugarcane bagasse. We conclude gasifies efficiency is 70%, the conversion rate is appropriate for estimating the calorific mass of the fuel gas produced can be recovered in a combustion heating value of the synthesis gas is about 10% power gas heating and heat losses are 30%.

  20. Cinética do consumo de oxigênio e tempo limite na vvo2max: comparação entre homens e mulheres Oxygen uptake kinetics and threshold time at the vVO2max: tomparison between men and women

    OpenAIRE

    Paulo Henrique Silva Marques de Azevedo; João Carlos Oliveira; Herbert Gustavo Simões; Vilmar Baldissera; Sérgio Eduardo de Andrade Perez

    2010-01-01

    Foi investigada a influência do gênero no tempo limite (Tlim) e na cinética do VO2 durante corrida na velocidade associada ao VO2max (vVO2max) em nove homens e nove mulheres, todos adultos, jovens e sedentários, com idades entre 20 e 30 anos. Homens e mulheres realizaram dois testes em esteira rolante, sendo um teste incremental para determinar VO2max (42,66 ± 4,50 vs. 32,92 ± 6,03mL.kg-1.min-1) e vVO2max (13.2 ± 1.5 vs. 10,3 ± 2,0km.h-1), respectivamente. Um segundo teste com carga c...

  1. Hot corrosion behaviour of Fe-Al based intermetallic in molten NaVO{sub 3} salt

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Medina, M.A. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas Norte No. 152, Col. San Bartolo Atepehuacan, C.P. 07730 Mexico, D.F. (Mexico)], E-mail: maespin@imp.mx; Carbajal-De la Torre, G. [Facultad de Ingenieria Mecanica, UMSNH, Santiago Tapia 403 Col. Centro, C.P. 58098 Morelia, Michoacan (Mexico); Liu, H.B. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas Norte No. 152, Col. San Bartolo Atepehuacan, C.P. 07730 Mexico, D.F. (Mexico); Martinez-Villafane, A. [CIMAV, Complejo Industrial Chihuahua, Chihuahua (Mexico); Gonzalez-Rodriguez, J.G. [CIMAV, Complejo Industrial Chihuahua, Chihuahua (Mexico); UAEM-CIICAP, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos (Mexico)

    2009-06-15

    The hot corrosion of sprayed Fe-40 (at.%)Al intermetallic alloy with additions of boron and alumina whiskers in molten NaVO{sub 3} at 700 deg. C has been evaluated by potentiodynamic polarization curves and electrochemical impedance spectroscopy, EIS, techniques. For short exposure times, the corrosion mechanism under these conditions was observed to be controlled by an activation process, whereas for longer exposure times, the corrosion process was under diffusion control due to the growing of an Al{sub 2}O{sub 3} oxide scale, which made the diffusion of both reducing and oxidizing species through the scale to the alloy or scale surfaces more difficult. Equivalent electric model used to simulate the EIS data showed that a finite length Warburg diffusion could properly characterize the diffusion process, which confirmed the formation of a compact corrosion product scales containing rich aluminium oxide. Thus, the corrosion process was under diffusion control of aggressive ions through the formed scale. The electrochemical study was complemented by scanning electronic microscopy characterization and micro chemical analysis.

  2. Budúcnos? Slovenska vo svetle štátneho rozpo?tu na rok 2013

    Directory of Open Access Journals (Sweden)

    Mikuláš Huba

    2012-12-01

    Full Text Available Úvahám o budoucnosti se v?nuje i následující ?lánek – jeho autor (ze svého pohledu v sou?asnosti nevyslyšeného zákonodárce ukazuje realitu budoucího vývoje na Slovensku, jak je vt?lena do konkrétních plánovaných výdaj? státního rozpo?tu, a která v této své realistické podob? kontrastuje nejen s programovým prohlášením vlády, ale ?asto i s prostým rozumem. Vybírá nejz?eteln?jší a nejvíce nelogické ukázky nejen antiekologické zaslepenosti, ale též (a pravd?podobn? v souvislosti s ní nehospodárného a krátkozrakého p?ístupu ekonomického.

  3. Investigation into isomolar series of Al(NO3)3, Na3VO4 solution mixture and composition of solid phases

    International Nuclear Information System (INIS)

    Conducted is investigation of properties of isomolar series of aluminium nitrate and sodiUm vanadate solutions at pH of the latter 12.5; 10.0; 7.0 and the temperature of 25 deg C using the methods of pH-metry, conductometry, ''seeming'' volume of precipitations, residual concentration of aluminium and vanadium. It is shown, that the composition property diagram of the system investigated does not reflect the true composition of solid-phase products of the reaction, which depends on the component ratio in solution. Bottom phases of isomolar series are mainly heterogeneous. At the excess of sodium vanadate solution and its high pH values conditions for the basic salt formation are created. At pH of the Na3VO4 solution of 12.5 and 10.0 and Al(NO3)3: Na3VO4 ratios 4:6 and 3:7 respectively obtained are the basic aluminium vanadates of the (AlOH)3(VO4)2x 7.5H2O and (AlOH)2V2O7x5H2O composition, some of their physicochemical properties being investigated

  4. VO2 pico e inclinação VE/VCO2 na era dos betabloqueadores na insuficiência cardíaca: uma experiência brasileira / Peak VO2 and VE/VCO2 slope in betablockers era in patients with heart failure: a brazilian experience

    Scientific Electronic Library Online (English)

    Guilherme Veiga, Guimarães; Mário Sérgio Vaz da, Silva; Veridiana Moraes, d' Avila; Silvia Moreira Ayub, Ferreira; Christiano Pereira, Silva; Edimar Alcides, Bocchi.

    2008-07-01

    Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in portuguese FUNDAMENTO: Estudos têm demonstrado que o consumo de oxigênio de pico (VO2 pico) e a inclinação VE/VCO2 são preditores de sobrevida em pacientes com insuficiência cardíaca (IC). Entretanto, com a adição do betabloqueador no tratamento da IC, os valores de prognóstico do VO2 pico e da Inclinação VE/V [...] CO2 não estão totalmente estabelecidos. OBJETIVO: Avaliar o efeito dos betabloqueadores no valor de prognóstico do VO2 pico e da inclinação VE/VCO2 em pacientes com IC. MÉTODOS: Estudamos 391 pacientes com insuficiência cardíaca, com idade de 49 ± 14 anos e fração de ejeção do ventrículo esquerdo de 38 ± 10%. Total de pacientes que usavam (grupo I - GI) e não usavam (grupo II - GII) betabloqueadores: 229 e 162, respectivamente. Todos os pacientes foram submetidos a teste de esforço cardiopulmonar, em esteira, usando o protocolo de Naughton. RESULTADOS: O VO2 pico 16 ml.kg-1.min-1 categorizaram pacientes com melhor prognóstico em médio prazo. A faixa do VO2 pico entre > 10 e Abstract in english BACKGROUND: Studies have demonstrated that peak oxygen consumption (peak VO2) and the VE/VCO2 slope are predictors of survival in patients with heart failure (HF). However, with the advent of betablockers in the treatment of HF, the prognostic values of peak VO2 and VE/VCO2 slope have not been fully [...] established. OBJECTIVE: To evaluate the effect of betablocker use on the prognostic value of peak VO2 and VE/VCO2 slope in patients with HF. METHODS: We studied 391 patients with heart failure, aged 49 ± 14 years and presenting a left ventricular ejection fraction of 38 ± 10%. The total number of patients that used (Group I - GI) or did not use (Group II - GII) betablockers was 229 and 162, respectively. All patients were submitted to a cardiopulmonary stress test on a treadmill, using the Naughton protocol. RESULTS: A peak VO2 16 ml.kg-1.min-1 categorizes patients with a better mid-term prognosis. Peak VO2 values between > 10 and

  5. A novel open-framework with non-crossing channels in the uranyl vanadates A(UO2)4(VO4)3 (A=Li, Na)

    International Nuclear Information System (INIS)

    A new sodium uranyl vanadate Na(UO2)4(VO4)3 has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. It crystallizes in the tetragonal symmetry with space group I41/amd and following cell parameters: a=7.2267(4) A and c=34.079(4) A, V=1779.8(2) A3, Z=4 with ?mes=5.36(3) g/cm3 and ?cal=5.40(2) g/cm3. A full-matrix least-squares refinement on the basis of F2 yielded R1=0.028 and wR2=0.056 for 52 parameters with 474 independent reflections with I?2?(I) collected on a BRUKER AXS diffractometer with MoK? radiation and a CCD detector. The crystal structure is characterized by ?2[(UO2)2(VO4)] sheets parallel to (001) formed by corner-shared UO6 distorted octahedra and V(2)O4 tetrahedra, connected by V(1)O4 tetrahedra to ?1[UO5]4- chains of edge-shared UO7 pentagonal bipyramids alternately parallel to the a- and b-axis. The resulting three-dimensional framework creates mono-dimensional channels running down the a- and b-axis formed by face-shared oxygen octahedra half occupied by Na. The powder of Li analog compound Li(UO2)4(VO4)3 has been synthesized by solid-state reaction. The tw by solid-state reaction. The two compounds exhibit high mobility of the alkaline ions within the two-dimensional network of non-intersecting channels

  6. Synthesis and characterization of the new layered perovskite, Na0.10(VO)0.45LaTiO4·nH2O

    International Nuclear Information System (INIS)

    Na0.10(VO)0.45LaTiO4·nH2O (n congruent with 0.6) has been synthesized by an ion exchange reaction between the single-layered perovskite, NaLaTiO4, and aqueous VOSO4. This low temperature phase retains the structure of the parent with a slight contraction of its tetragonal unit cell. Rietveld refinement of X-ray powder diffraction data indicate that the vanadyl units are disordered within the perovskite layers. Infrared spectroscopy, electron spin resonance and magnetic susceptibility are consistent with the presence of isolated vanadyl units. Susceptibility data show Curie-Weiss behavior above 140 K

  7. Predição da potência aeróbia (VO2máx de crianças e adolescentes em teste incremental na esteira rolante Prediction of aerobic power (VO2max of children and adolescents during an incremental treadmill test

    Directory of Open Access Journals (Sweden)

    Fabiana Andrade Machado

    2013-03-01

    Full Text Available O consumo máximo de oxigênio (VO2máx é a quantidade máxima de energia que pode ser produzida pelo metabolismo aeróbio em determinada unidade de tempo, podendo ser determinado direta ou indiretamente através de equações preditivas. O objetivo deste trabalho foi elaborar uma equação preditiva específica para determinar o VO2máx de meninos de 10 a 16 anos. Quarenta e dois meninos realizaram teste ergoespirométrico de corrida em esteira rolante com velocidade inicial de 9 km/h até exaustão voluntária. Através da regressão linear múltipla foi possível desenvolver a seguinte equação para a determinação indireta do VO2máx: VO2máx (ml/min = -1574,06 + (141,38 x Vpico + (48,34 * Massa corporal, com erro padrão de estimativa = 191,5 ml/min (4,10 ml/kg/min e o coeficiente de determinação = 0,934. Sugerimos que esta é uma fórmula adequada para predizer o VO2máx para esta população.The maximal oxygen uptake (VO2max is the maximal quantity of energy that can be produced by the aerobic metabolism in certain time unity. It can be determined direct or indirectly by predictive equations. The objective of this study was to make a specific predictive equation to determine the VO2max from boys aged 10-16 years-old. Forty-two boys underwent a treadmill running ergospirometric test, with the initial velocity set at 9 km/h, until voluntary exhaustion. By the multiple linear regression was possible to develop the following equation for the indirect determination of the VO2max: VO2max (ml/min = -1574.06 + (141.38 x Vpeak + (48.34 * Body mass, with standard error of estimate = 191.5 ml/min (4.10 ml/kg/min and coefficient of determination = 0.934. We suggest that this formula is appropriate to predict VO2max for this population.

  8. A detailed study of the dehydration process in synthetic strelkinite, Na[(UO{sub 2})(VO{sub 4})] . nH{sub 2}O (n = 0, 1, 2)

    Energy Technology Data Exchange (ETDEWEB)

    Suleimanov, Evgeny V.; Somov, Nikolay V.; Chuprunov, Evgeny V.; Mayatskikh, Ekaterina F. [Nizhny Novgorod State Univ. (Russian Federation); Depmeier, Wulf [Kiel Univ. (Germany). Inst. fuer Geowissenschaften; Alekseev, Evgeny V. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie- und Klimaforschung (IEK-6)

    2012-11-01

    Synthetic strelkinite Na[(UO{sub 2})(VO{sub 4})] . nH{sub 2}O (n = 0, 1, 2) was systematically investigated by single crystal X-ray diffraction and thermoanalytical methods. The anhydrous form and two hydrates were isolated as single crystals and the structures of these phases solved: Na[(UO{sub 2})(VO{sub 4})], monoclinic, P2{sub 1}/c, a = 6.0205(1) Aa, b = 8.3365(1) Aa, c = 10.4164(2) Aa, {beta} = 100.466(2) , V = 514.10(1) Aa{sup 3}, R{sub 1} = 0.0337; Na[(UO{sub 2})(VO{sub 4})] . H{sub 2}O, monoclinic, P2{sub 1}/c, a = 7.722(2) Aa, b = 8.512(1) Aa, c = 10.480(4) Aa, {beta} = 113.18(3) , V = 633.3(3) Aa{sup 3}, R{sub 1} = 0.1658; Na[(UO{sub 2})(VO{sub 4})] . 2 H{sub 2}O, monoclinic, P2{sub 1}/n, a = 16.2399(5) Aa, b = 8.2844(2) Aa, c = 10.5011(2) Aa, {beta} = 97.644(2) , V = 1400.24(6) Aa{sup 3}, R{sub 1} = 0.0776. A possible mechanism of the structural transformation processes during dehydration is proposed based on the structures of the anhydrous phase and the hydrates. (orig.)

  9. Inclusão do equivalente do lactato sanguíneo O2 na regressão de intensidade de exercício VO2 aumenta o gasto energético de corrida e diminui sua precisão / Inclusion of blood lactate O2 equivalent in the VO2 exercise intensity regression increases the energy cost of running and lowers its precision / La inclusión del equivalente del lactato sanguíneo O2 en la regresión de intensidad de ejercicio VO2 aumenta el gasto energético de la carrera y disminuye su precisión

    Scientific Electronic Library Online (English)

    Victor Machado, Reis; Diogo Roberto, Oliveira; André Luiz, Carneiro; Tiago Manuel, Barbosa.

    2013-12-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese INTRODUÇÃO E OBJETIVOS: Investigar se a inclusão do equivalente energético de lactato sanguíneo (LS) em intensidades submáximas alteraria o gasto energético de corrida (Gc) estimado para corrida supramáxima de alta intensidade assim como sua precisão MÉTODOS: O Gc foi determinado a partir da curva d [...] e regressão de velocidade do VO2. Para cada sujeito, uma regressão alternativa foi estabelecida em que energia equivalente a 3 ml de O2 kg-1?mM-1 de LS foi adicionada ao VO2. Testes t pareados, correlações pareadas e plotagem de Bland-Altman foram utilizados para investigar se os dois métodos representam os mesmos fenômenos. RESULTADOS: Os principais achados foram que o Gc previsto para intensidades supramáximas incluídos entre 110 e 160% ao correspondente ao pico de VO2 dos indivíduos aumentou significativamente quando as medidas de LS foram incluídas nas regressões. A inclusão das medidas de LS também aumentaram a imprecisão do Gc a 110, 120, 130, 150 e 160%. CONCLUSÃO: Nossos resultados indicam que a inclusão do equivalente do lactato de O2 na regressão de intensidade de VO2-exercício aumenta o gasto energético e diminui sua precisão. Abstract in spanish INTRODUCCIÓN Y OBJETIVOS: Investigar si la inclusión del equivalente energético de lactato sanguíneo (LS), en intensidades submáximas, modificaría el gasto energético de la carrera (Gc), estimado para carrera supramáxima de alta intensidad, así como su precisión. MÉTODOS: El Gc fue determinado a par [...] tir de la curva de regresión de velocidad del VO2. Para cada individuo, se estableció una regresión alternativa en la cual energía equivalente a 3 ml de O2 kg-1?mM-1 de LS fue adicionada al VO2. Pruebas t por pares, correlaciones por pares y plotaje de Bland-Altman fueron utilizados para investigar si los dos métodos representan los mismos fenómenos. RESULTADOS: Los hallazgos principales fueron que el Gc previsto para intensidades supramáximas, incluidos 110% y 160% de lo que corresponde al pico de VO2 de los individuos, aumentó significativamente cuando las medidas de LS fueron incluidas en las regresiones. La inclusión de las medidas de LS también aumentó la imprecisión del Gc a 110%, 120%, 130%, 150% y 160%. CONCLUSIÓN: Nuestros resultados indican que la inclusión del equivalente del lactato de O2, en la regresión de intensidad de VO2-ejercicio, aumenta el gasto energético y disminuye su precisión. Abstract in english INTRODUCTION AND OBJECTIVES: Investigate whether the inclusion of the blood lactate (BL) energy equivalent at submaximal intensities would change the energy cost of running (CR) predicted to supramaximal high-intensity running as well as its precision. METHODS: The CR was determined from the slope o [...] f the VO2-speed regression. For each subject an alternative regression was established where an energy equivalent of 3 ml O2 kg-1?mM-1 BL was added to the VO2. Paired t-tests, pairwise correlations and Bland-Altman plots were used to investigate whether the two methods represent the same phenomena. RESULTS: The main findings were that CR predicted to supramaximal intensities comprised between 110% and 160% of that corresponding to the individuals' peak VO2, increased significantly when the BL measurements were included in the regressions. The inclusion of BL measurements also increased the imprecision of the CR at 110%, 120%, 130%, 150% and 160%. CONCLUSIONS: Our results indicate that inclusion of lactate O2 equivalent in the VO2-exercise intensity regression increases the energy cost of running and lowers its precision.

  10. Predição da potência aeróbia (VO2máx) de crianças e adolescentes em teste incremental na esteira rolante / Prediction of aerobic power (VO2max) of children and adolescents during an incremental treadmill test

    Scientific Electronic Library Online (English)

    Fabiana Andrade, Machado; Benedito Sérgio, Denadai.

    2013-03-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O consumo máximo de oxigênio (VO2máx) é a quantidade máxima de energia que pode ser produzida pelo metabolismo aeróbio em determinada unidade de tempo, podendo ser determinado direta ou indiretamente através de equações preditivas. O objetivo deste trabalho foi elaborar uma equação preditiva específ [...] ica para determinar o VO2máx de meninos de 10 a 16 anos. Quarenta e dois meninos realizaram teste ergoespirométrico de corrida em esteira rolante com velocidade inicial de 9 km/h até exaustão voluntária. Através da regressão linear múltipla foi possível desenvolver a seguinte equação para a determinação indireta do VO2máx: VO2máx (ml/min) = -1574,06 + (141,38 x Vpico) + (48,34 * Massa corporal), com erro padrão de estimativa = 191,5 ml/min (4,10 ml/kg/min) e o coeficiente de determinação = 0,934. Sugerimos que esta é uma fórmula adequada para predizer o VO2máx para esta população. Abstract in english The maximal oxygen uptake (VO2max) is the maximal quantity of energy that can be produced by the aerobic metabolism in certain time unity. It can be determined direct or indirectly by predictive equations. The objective of this study was to make a specific predictive equation to determine the VO2max [...] from boys aged 10-16 years-old. Forty-two boys underwent a treadmill running ergospirometric test, with the initial velocity set at 9 km/h, until voluntary exhaustion. By the multiple linear regression was possible to develop the following equation for the indirect determination of the VO2max: VO2max (ml/min) = -1574.06 + (141.38 x Vpeak) + (48.34 * Body mass), with standard error of estimate = 191.5 ml/min (4.10 ml/kg/min) and coefficient of determination = 0.934. We suggest that this formula is appropriate to predict VO2max for this population.

  11. Growth of YbVO4 crystals evolved from hot corrosion reactions of Yb2Zr2O7 against V2O5 and Na2SO4 + V2O5

    Science.gov (United States)

    Li, Sa; Liu, Zhan-Guo; Ouyang, Jia-Hu

    2013-07-01

    Hot corrosion behavior of Yb2Zr2O7 ceramic against V2O5 and Na2SO4 + V2O5 (molar ratio = 1:1) was investigated at temperatures of 900-1100 °C for 2 h in air. YbVO4 was identified due to chemical interactions of these two corrosive agents with Yb2Zr2O7 ceramic. Although YbVO4 formed in these two hot corrosion reactions has the same crystallographic structural characteristic, its morphologies exhibit significant difference. YbVO4 evolved from hot corrosion of V2O5-coated Yb2Zr2O7 is particle-shaped, while it is rod-like in the (Na2SO4 + V2O5)-coated Yb2Zr2O7. A model describing the formation process of the hot corrosion products was presented and the growth mechanism of YbVO4 crystal was proposed on the basis of the hot corrosion model.

  12. PRETRATAMIENTOS DE LA CELULOSA Y BIOMASA PARA LA SACARIFICACIÓN

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    ANDERSON GUARNIZO FRANCO

    2009-01-01

    Full Text Available La biomasa celulósica se ha vuelto un producto interesante para ser aprovechada como materia prima en la fabricación de biocombustibles, especialmente el etanol. El paso crítico en su conversión a etanol, implica la degradación de los polisacáridos a azúcares fermentables, en un proceso denominado sacarificación. La celulosa, el componente principal de la biomasa, es un polisacárido de difícil degradación en condiciones de tratamiento moderadas. Las investigaciones más recientes en el campo de los biorecursos, se han enfocado hacia el desarrollo de ciertos pretratamientos de la biomasa o la celulosa bajo los cuales se logra que estos materiales sean de más fácil degradación a azúcares fermentables. El presente artículo resume los resultados más sobresalientes, sin ser exhaustivos, de los pretaratimentos de la celulosa y la biomasa para su conversión a productos fermentables por la ruta etanólica.

  13. Potencial de producción de biomasa en una población natural de la ostra crassostrea rhizophorae, en la laguna grande de obispo, Golfo de Cariaco, Venezuela / Biomass production potential in a natural population of the oyster crassostrea rhizophorae in laguna grande de obispo; Cariaco Gulf; Venezuela / Potencial de produção de biomassa na população natural da ostra crassostrea rhizophorae, na lagoa grande de obispo, Golfo de Cariaco, Venezuela

    Scientific Electronic Library Online (English)

    Antulio, Prieto; Andrés, Montes; Lilia J, Ruiz.

    2008-10-08

    Full Text Available A ostra Crassostrea rhizophorae é um bivalves de interesse comercial, comum nas comunidades de manglares no oriente da Venezuela. Para avaliar o potencial de geração de biomassa da espécie se realizaram amostras mensais desde maio de 2002 até maio de 2003, em duas estações da população natural de La [...] guna Grande do Obispo, estado Sucre, Venezuela. Utilizando um desenho de amostras aleatório simples se determinou a abundância e a biomassa de bivalves fixados a raízes de Rhizophora manglae, estimando a produção secundária pelo método da taxa específica de crescimento. Determinou-se uma densidade média de 818,13ind/m² de raiz com biomassa média em peso seco de 662,39g/m², sem diferenças significativas entre estações nem meses. Utilizando um modelo de crescimento com parâmetros finais de L¥= 87,68 e K= 0,19/mês, se obteve uma produção secundária total de 2.355,546g/m²/ano, sendo o intervalo de tamanho 50,01-60,00mm o que aportou a maior quantidade (382,353g/m²/ano). A máxima produção se obteve em jan-fev de 2003 (243,906g/m²/ano) e a mínima em mai-jun de 2002 (100,80g/m²/ano). A produção por indivíduo foi de 43,283g/m²/ano com a mesma tendência temporal da total. Ainda que não se determinasse correlação dos incrementos de produção com a temperatura e salinidade, a maior produção ocorreu durante a época de surgência costeira na zona. A relação produção/biomassa foi de 3,55/ano, resultados que indicam que C. rhizophorae apresenta um grande potencial para atividades de aqüicultura na zona por sua reprodução continua e altas taxas de crescimento e produtividade. Abstract in spanish La ostra Crassostrea rhizophorae es un bivalvo de interés comercial, común en las comunidades de manglar en el oriente de Venezuela. Para evaluar el potencial de generación de biomasa de la especie se realizaron muestreos mensuales desde mayo 2002 hasta mayo 2003, en dos estaciones de la población n [...] atural de Laguna Grande del Obispo, estado Sucre, Venezuela. Utilizando un diseño de muestreo al azar simple se determinó la abundancia y la biomasa de bivalvos fijados a raíces de Rhizophora manglae, estimando la producción secundaria por el método de la tasa específica de crecimiento. Se determinó una densidad promedio de 818,13ind/m² de raíz con biomasa promedio en peso seco de 662,39g/m², sin diferencias significativas entre estaciones ni meses. Utilizando un modelo de crecimiento con parámetros finales de L¥= 87,68 y K= 0,19/mes, se obtuvo una producción secundaria total de 2355,546g/m²/año, siendo el intervalo de talla 50,01-60,00mm el que aportó la mayor cantidad (382,353g/m²/año). La máxima producción se obtuvo en ene-feb 2003 (243,906g/m²/año) y la mínima en may-jun 2002 (100,80g/m²/año). La producción por individuo fue de 43,283g/m²/año con la misma tendencia temporal de la total. Aunque no se determinó correlación de los incrementos de producción con la temperatura y salinidad, la mayor producción ocurre durante la época de surgencia costera en la zona. La relación producción/biomasa fue de 3,55/año, resultados que indican que C. rhizophorae presenta un gran potencial para actividades de acuicultura en la zona por su reproducción continua y altas tasas de crecimiento y productividad. Abstract in english The oyster Crassostrea rhizophorae is a bivalve of commercial interest, common in mangrove communities of eastern Venezuela. This study was conducted in order to evaluate the production of biomass of species in a natural population of Laguna Grande de Obispo, Cariaco Gulf, Venezuela. Monthly samplin [...] gs were carried out between May 2002 and May 2003 in two stations. Using a simple random sampling design, the abundance and biomass of bivalves fixed on mangrove roots Rhizophora manglae were determined, estimating the secondary production by the specific growth rate method. Mean density was 818.13ind/m² and mean biomass was 662.39g/m² of root, without significant differences between stations and months. Using a gr

  14. ESTIMACIÓN DE BIOMASA AÉREA EN CULTIVOS CON SENSORES REMOTOS

    Directory of Open Access Journals (Sweden)

    Ferm\\u00EDn Pascual-Ram\\u00EDrez

    2012-01-01

    Full Text Available Para estimar la producción de biomasa aérea en cultivos utilizando sensores remotos se realizaron análisis de la producción de biomasa e información espectral en cinco cultivos medidos en campo, durante una campaña de muestreo en el Valle del Yaqui, Sonora. La información espectral fue procesada hasta la obtención del índice de vegetación iso-suelo (IVIS. Los análisis multitemporales muestran un comportamiento similar entre el desarrollo de los cultivos y el valor del IVIS, por lo que se obtuvo una relación lineal entre ellos. De manera similar fueron analizados el índice de cosecha y su relación con el IVIS. Los resultados mostraron que el IVIS es un índice adecuado para la estimación de biomasa y rendimiento en cultivos.

  15. ECUACIONES ALOMÉTRICAS PARA ESTIMAR BIOMASA Y CARBONO EN Quercus magnoliaefolia

    Directory of Open Access Journals (Sweden)

    Jes\\u00FAs D. G\\u00F3mez-D\\u00EDaz

    2011-01-01

    Full Text Available En el ejido El Zapote de la Reserva de la Biosfera "Sierra de Huautla", estado de Morelos, México, se seleccionaron doce árboles de Quercus magnoliaefolia Née y se determinó su biomasa en la parte aérea. El modelo alométrico quedó expresado como: B = 0.0345 * DAP2.9334 en donde B es la biomasa (kg y DAP es el diámetro a la altura del pecho (cm, con un coeficiente de determinación (R2= 0.98; P<0.001. Adicionalmente, se estimó la biomasa mediante una regresión lineal múltiple que consideró el área basal (AB, la densidad específica de la madera (DEM y la altura de los árboles (H. Una alta proporción de la varianza de la biomasa fue explicada solamente por el área basal. La DEM y H no incrementaron significativamente la precisión de los modelos. El porcentaje promedio de carbono en los árboles de Q. magnoliaefolia fue de 47.14 con valores de 46.29 % para el fuste, 46.83 % para las ramas y 48.31 % para el follaje. La proporción promedio de los componentes de la especie estudiada fue de 2.5 % para el fuste, 27.8 % para las ramas y 9.6 % para el follaje.

  16. Solid Biomass Consumption in Households and Greenhouse Gas Emission Reduction in Latvia / CIET?S Biomasas PAT?RI?Š un SILTUMN?CEFEKTA G?ZU Emisiju SAMAZIN?ŠANAS PERSPEKT?VA Latvijas M?JSAIMNIEC?B?S

    Science.gov (United States)

    Kudrenickis, I.; Klavs, G.

    2013-12-01

    Utilisation of biomass is an important factor in reducing emission of greenhouse gases (GHG); at the same time, high efficiency of biomass combustion technologies is to be ensured to minimise the methane (CH4) emission thus achieving the most efficient reduction in the total GHG emission. The authors analyse the GHG emission breakdown in Latvia among the sectors not included in the EU Emissions Trading Scheme (ETS), and, in the context of emission reduction, evaluate the energy supply in the Latvian household sector, the types of combustion technologies and the used fuels. The trend is considered for the CH4 emission factor during 1990-2010 in the household sector of EU countries, and the numerical index is calculated which illustrates decoupling the consumption of biomass fuel from CH4 emission. To evaluate the perspective of CH4 emission reduction in the Latvian household sector, two scenarios are investigated for efficiency improvement as related to the central heating equipment based on wood fuel. Biomasas izmantošana ir viens no principi?lajiem virzieniem siltumn?cefekta g?zu (SEG) emisiju samazin?šan?. Maksim?la SEG emisiju samazin?juma pan?kšanai ir nepieciešams nodrošin?t biomasas sadedzin?šanas iek?rtu augstu efektivit?ti, lai minimiz?tu ar biomasas kurin?m? pat?ri?u saist?to met?na (CH4) emisiju pieaugumu. Autori raksturo Eiropas Savien?bas (ES) Emisiju kvotu tirdzniec?bas sist?mas (ETS) un taj? neietilpstošo sektoru (ne-ETS) noz?mi Latvijas SEG emisiju veidošan?, SEG emisiju relat?vo sadal?jumu atbilstoši daž?diem ne- ETS sektoriem un SEG emisiju samazin?šanas kontekst? analiz? Latvijas m?jsaimniec?bu sektora energoapg?di, pat?r?to kurin?mo un izmantot?s kurin?m? sadedzin?šanas tehnolo?ijas. Rakst? ir demonstr?ta SEG emisiju inventariz?cij? pielietot? CH4 emisiju specifisk? faktora m?jsaimniec?bu sektora koksnes kurin?majam skaitlisko v?rt?bu dinamika 1990-2010 gados daž?d?s ES valst?s. Sal?dzinot kurin?m? pat?ri?a un CH4 emisiju apjoma izmai?as, ir apr??in?ts skaitliskais r?d?t?js, kas raksturo biomasas kurin?m? pat?ri?a un CH4 emisiju "atsaisti" ES valst?s analiz?jam? laika posm?. Lai kvantitat?vi nov?rt?tu CH4 emisiju samazin?šanas perspekt?vu Latvijas m?jsaimniec?bu sektor?, autori analiz? divus att?st?bas scen?rijus, kas paredz daž?dus m?jsaimniec?bu centr?laj? apkur? izmantoto koksnes sadedzin?šanas iek?rtu efektivit?tes pieaugumus.

  17. EFECTO DEL CARBONATO DE POTASIO EN LA EVOLUCIÓN DE LOS GRUPOS FUNCIONALES DE LOS BIOCRUDOS DE CONVERSIÓN HIDROTÉRMICA DE BIOMASA LIGNOCELULÓSICA ALREDEDOR DEL PUNTO CRÍTICO DEL AGUA / POTASSIUM CARBONATE EFFECT ON BIOCRUDE FUNCTIONAL GROUPS EVOLVING FROM LIGNOCELLULOSIC BIOMASS UNDERGOING HYDROTHERMAL CONVERSION CLOSE TO THE CRITICAL POINT OF WATER / EFEITO DO CARBONATO DE POTÁSSIO NA FORMAÇÃO DOS GRUPOS FUNCIONAIS DOS BIOPETRÓLEOS OBTIDOS POR CONVERSÃO HIDROTÉRMICA DE BIOMASSA LENHOCELULÓSICA PRÓXIMO DO PONTO CRÍTICO DA ÁGUA

    Scientific Electronic Library Online (English)

    Alejandro A, Castro; Andrés, Anzola; Iván, Cagua; Luis I, Rodríguez; Yazmín, Agámez; Orlando, Hernández; José de J, Díaz.

    2008-08-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in portuguese Um tipo de biomassa pobre em lenhina, do género Pennisetum, foi submetido ao processo de conversão hidrotérmica na presença de carbonato de potássio como catalisador. As reacções foram conduzidas em condições próximas do ponto crítico da água. Os produtos de reacção não aquosos (biopetróleo) foram s [...] eparados por decantação e analisados por espectroscopia de infravermelho. Os biopetróleos obtidos contêm compostos com funcionalidades aromáticas, olefínicas, hidroxiladas, éteres e, no caso do biopetróleo obtido sob condição subcrítica, funções carbonilo. A fracção gasosa e a quantidade de biopetróleo aumentam na presença de carbonato de potássio. Abstract in spanish Un tipo de biomasa pobre en lignina, del género Pennisetum, fue sometida al proceso de conversión hidrotérmica en presencia de carbonato de potasio como catalizador. Las reacciones se llevaron a cabo en ambientes cercanos al punto crítico del agua. Los productos de reacción no acuosos (biocrudo) se [...] separaron por decantación y se analizaron por espectrometría infrarroja. Los biocrudos obtenidos contienen compuestos con funcionalidades aromáticas, olefínicas, hidroxiladas, éteres, y para el caso del biocrudo obtenido bajo la condición subcrítica funciones carbonilo. La fracción gaseosa y el biocrudo aumentan en presencia del carbonato de potasio. Abstract in english A type of poor-lignin biomass (Pennisetum sp.) was hydrothermally converted in the presence of potassium carbonate as catalyst. The reactions were carried out close to the critical point of the water. The non-aqueous (biocrude) reaction products were separated by decantation and were analyzed by inf [...] rared spectrometry. The biocrude products so obtained contained compounds having aromatic, olephinic, hydroxylated and ether functionalities; sub-critical biocrude had carbonyl functions. The gaseous and biocrude fractions increased in the presence of potassium carbonate.

  18. Cambios en la biomasa de raíces y micorrizas arbusculares en cultivos itinerantes del Amazonas Venezolano / Changes in root biomass and arbuscular mycorrhizae in shifting crops of the Venezuelan Amazon / Mudanças na biomassa de raízes e micorrizas arbusculares em cultivos itinerantes do Amazonas Venezolano

    Scientific Electronic Library Online (English)

    Carolina, Kalinhoff; Alicia, Cáceres; Leonardo, Lugo.

    2009-08-01

    Full Text Available SciELO Venezuela | Language: Spanish Abstract in portuguese A designação de biomassa a produção de raízes finas em plantas terrestres e a formação de associações simbióticas micorrízico arbusculares (MA) constituem adaptações de importância em condições de baixa fertilidade. Em um mosaico de agricultura itinerante, conformado por duas áreas de cultivo (parce [...] las), duas áreas de 2-4 e de 4-6 anos de abandono depois de ser cultivadas (pousios) e uma área de bosque chuvoso pouco perturbado, se compararam a biomassa de raízes finas (diâmetro Abstract in spanish La asignación de biomasa a la producción de raíces finas en plantas terrestres y la formación de asociaciones simbióticas micorrízico arbusculares (MA) constituyen de importantes adaptaciones en condiciones de baja fertilidad. En un mosaico de agricultura itinerante, conformado por dos áreas de cult [...] ivo (conucos), dos áreas de 2-4 y de 4-6 años de abandono después de ser cultivadas (barbechos) y un área de bosque lluvioso poco perturbado, se compararon la biomasa de raíces finas (diámetro Abstract in english The allocation of biomass to the production of fine roots in terrestrial plants and arbuscular mycorrhizal (AM) symbiotic partnerships are important adaptations under conditions of low fertility. In a mosaic of shifting cultivation, comprising two growing areas (conucos) and two 2-4 and 4-6 years de [...] serted areas after being cultivated (fallow), and a little disturbed rain forest area, differences in fine root biomass (diameter

  19. Generación eléctrica a partir de biomasa en una destilería diversificada

    Directory of Open Access Journals (Sweden)

    Pedro A. Rodr\\u00EDguez

    2007-01-01

    Full Text Available La instalación de una destilería de etanol diversificada, como una vía de generación de energía renovable integrada a la producción de alimentos, muestra relevantes ventajas en comparación con las destilerías tradicionales. En particular, para el caso de una planta de producción de etanol de este tipo, de 1200 hL/d, la generación de electricidad, con la biomasa que esta industria genera, alcanza el valor de 15,92 MW de potencia eléctrica excedente para el Sistema Electroenergético Nacional. Constituye un polo de desarrollo económico, social y estratégico, atendiendo al concepto de autosustentación dado por el Protocolo de Kyoto. El concepto de diversificación alcanza a todo el sector productivo. En las destilerías tradicionales la diversificación es incipiente. La biomasa constituye una de las principales fuentes de generación de energía limpia y barata, pasando de ser un subproducto, a un eslabón fundamental del proceso productivo.

  20. La biomasa en la producción de electricidad en España

    Directory of Open Access Journals (Sweden)

    Espejo Marín, Cayetano

    2005-06-01

    Full Text Available The generation of electricity using biomass began in Spain in the mid-1990s. In this paper, we examine the combustible products used in the generation of this type of electricity, the legal framework protecting its production, the evolution of the installed power and its territorial distribution, the environmental impact of biomass as a renewable energy, the energy policy supporting this technology and the problems for the development of biomass as a energy source in Spain.

    [es] La producción de electricidad con biomasa comienza su desarrollo en España a mediados de los años noventa. En este artículo se analizan los productos combustibles de biomasa destinados a la generación de electricidad, el marco legal que protege esta producción, la evolución de la potencia instalada y su distribución territorial, el impacto ambiental de la biomasa como energía renovable, la política energética de apoyo a esta tecnología, y los problemas para el desarrollo de la biomasa como fuente energética en España. [fr] La biomasse dans la production d´électricité en Espagne. La production d'électricité avec biomasse commence son développement en Espagne vers le milieu des années quatre-vingt-dix. Dans cet article nous analysons les produits combustibles de biomasse destines à engendrer de l'électricité, le cadre légal qui protégé cette production, l'évolution de la puissance installée, la répercussion de l'environnement de la biomasse comme énergie renouvelable, la politique énergétique de soutien à cette technologie et les problèmes pour le développement de la biomasse comme source énergétique en Espagne.

  1. Remoción y recuperación de cromo (III) de soluciones acuosas por biomasa de sorgo

    OpenAIRE

    Edguez, I. Cano Rodr U.; Rez, J. A. P. U. E.; Rrez, M. Guti U. E.; Gardea, J. L.

    2002-01-01

    En este trabajo se investigó la capacidad de la biomasa de ?desecho de sorgo? para remover y recuperar iones de cromo(III) de soluciones acuosas, tanto en sistemas en lote como en flujo continuo. Los resultados muestran que los iones de cromo(III) se unen preferentemente a la biomasa de sorgo a pH 4.5-5, después de 15 minutos de contacto, con una capacidad de saturación de aproximadamente 10 mg/g de biomasa seca. La biomasa inmovilizada fue capaz de remover y recuperar eficientemente ion...

  2. COMPARACIÓN DE UN REACTOR DE BIOMASA SUSPENDIDA Y UN REACTOR DE BIOMASA ADHERIDA PARA LA BIODEGRADACIÓN DE COMPUESTOS TÓXICOS PRESENTES EN AGUAS RESIDUALES DE REFINERÍAS DE PETRÓLEO

    Directory of Open Access Journals (Sweden)

    Lizet Marina NAVA URREGO

    2014-01-01

    Full Text Available Esta investigación comprende un estudio de tratamiento de aguas residuales de una refinería utilizando dos rectores biológicos discontinuos secuenciales (SBR, por sus siglas en inglés Sequencing Batch Reactor . El primero de ellos es un reactor de biomasa suspendida y el segundo es un reactor de biomasa adherida, en el cual se utilizaron soportes plásticos tipo Kaldnes K1. Debido a la diversidad y complejidad de las aguas residuales de refinerías, fue necesario aclimatar los microorganismos utilizando la estrategia de eficiencias fijas para garantizar una buena degradación de los compuestos difícilmente biodegradables o recalcitrantes. Los reactores operaron durante 45 días empleando ciclos de 24 h (llenado, tiempo de reacción, sedimentación, vaciado y tiempo muerto. La carga orgánica volumétrica aplicada a los reactores varió entre 0.44 - 0.54 kg DQO/m 3 d; las cargas orgánicas superficiales oscilaron entre 1.56 - 1.80 g DQO/m 2 d para el reactor de biomasa adherida. El desempeño de los reactores discontinuos secuenciales se evaluó mediante las eficiencias de remoción de DQO, COD y fenoles, obteniendo porcentajes de remoción de 75, 73 y 99 % en el reactor de biomasa suspendida, mientras que en el reactor de biomasa adherida se alcanzaron porcentajes de remoción de 77, 81 y 99 %, respectivamente. La concen - tración de sólidos suspendidos totales en el reactor de biomasa suspendida fue de aproximadamente 2200 mg SST/L mientras que en el reactor de biomasa adherida se registró entre 450 y 560 mg SST/L. La relación SSV/SST se mantuvo entre 0.8 y 1 en ambos reactores. La concentración de biomasa adherida a los soportes osciló entre 3.98 gST/m 2 y 5.45 gST/m 2 . En cada reactor se realizaron cuatro perfiles para evaluar la capacidad de los microorganismos para degradar el tipo sustrato al que fueron ex - puestos en un tiempo determinado. En ambos reactores, los perfiles de degradación 1 y 2 mostraron que la máxima remoción de DQO se presentó durante la primera hora de reacción, mientras que para los perfiles 3 y 4 la máxima remoción se alcanzó después de la segunda hora. En el caso de los fenoles, en todos los perfiles se obtuvo una remoción de más del 98 % durante la primera hora de reacción, indicando que en ambos reactores la biomasa fue capaz de degradar los compuestos tóxicos presentes en las aguas desflemadas sin importar el tipo de aglomeración microbiana utilizada

  3. Biomasa, proteína, taninos y rendimiento en haba en función del nitrógeno

    Directory of Open Access Journals (Sweden)

    Antioco Guadarrama Quiroz

    2007-01-01

    de la siembra (DDS; la floración, 60 DDS; y la madurez fisiológica, 125 DDS. El N no afectó la distribución o asignación (% de biomasa en las estructuras de la planta, pero incrementó la acumulación total de biomasa en cada estructura, el número de vainas m-2, el número de semillas m-2 y, en consecuencia, el rendimiento y la concentración de proteína. La concentración de taninos en haba no fue afectada por la aplicación de N.

  4. LA BIOMASA DE LOS CULTIVOS EN EL AGROECOSISTEMA. SUS BENEFICIOS AGROECOLÓGICOS

    Directory of Open Access Journals (Sweden)

    Anirebis Mart\\u00EDnez Romero

    2014-01-01

    Full Text Available La biomasa es el resultado de la transformación de la energía solar en energía química. El hombre a través de la historia la ha utilizado no solo para su alimentación sino también para la alimentación de sus animales. Los avances de la ciencia promovieron el desarrollo agrario basado en la revolución verde, la cual solo promueve la producción de alimentos ya sea de uso humano o animal, marginando la importancia de la biomasa como enriquecedor del recurso suelo al disponerse de los insumos necesarios para sustituir su fertilidad natural. En la actualidad la producción y conservación de la biomasa de cualquier cultivo cobra una importancia trascendente; porque ello contribuye, además, a la protección medioambiental a través de la captura de carbono. El presente trabajo tuvo como objetivo demostrar la importancia que proporciona la biomasa generalmente no alimenticia para los humanos, a fin de emplearla no solo como alimento animal, sino también como enriquecedora del recurso natural suelo. Las investigaciones realizadas en Cuba sobre el tema es pobre, aun cuando en la actualidad resulta de gran importancia encontrar variantes que permitan profundizar en la producción de biomasa en su relación con el medio ambiente. Finalmente se exponen los resultados preliminares sobre producción de biomasa a partir de la agrobiodiversidad presente en los escenarios productivos, a la vez que se reflexiona sobre la importancia del tema para futuras investigaciones.

  5. VO-Paris Data Centre (VO-PDC)

    Science.gov (United States)

    Le Petit, F.; Aboudarham, J.; Thuillot, W.; Le Sidaner, P.; Alimi, J.-M.; Désert, J.; Barache, C.; Berthier, J.; Boisson, C.; Bouquillon, S.; Combes, F.; Delahaye, F.; Deleflie, F.; Di Matteo, P.; Domisse, L.; Dubernet, M.-L.; Erard, S.; Gambis, D.; Guibert, J.; Haigron, R.; Hennebelle, P.; Jégouzo, I.; Henry, F.; Heydari-Malayeri, M.; Languignon, D.; Lambert, S.; Mamon, G.; Melchior, A.-L.; Normand, J.; Martin, J. M.; Moreau, N.; Pérault, M.; Rasera, Y.; Roueff, E.; Roy, F.; Royer, F.; Sahal-Bréchot, S.; Sarkissian, A.; Sartoretti, P.; Schneider, J.; Semelin, B.; Tajahmady, F.; Theureau, G.; Zolotukhin, I.; Zw"olf, C.-M.

    2012-09-01

    The VO-Paris Data Centre (VO-PDC) is a new data centre that gathers ten laboratories in the Paris area (GEPI, IAP, IMCCE, LATMOS, LERMA, LESIA, LPMAA, LUTH, SYRTE, USN). It is specialized in the development of Virtual Observatory services. The objective of this federation is to build a sustainable infrastructure to offer high quality diffusion services to the community. It gives also the opportunity to promote exchanges and to share expertise on the development of VO services between scientists and computer engineers. VO-PDC is a multidisciplinary data center. Its main axes are atomic and molecular physics, VO-Theory, planetology and solar physics. It also develops several services concerning the diffusion of traditional astronomical data, catalogues, as well as geodesy services.

  6. Empleo de la relación residuo producto para la estimación de biomasa cañera potencial. Caso de estudio

    Directory of Open Access Journals (Sweden)

    Lizet Rodr\\u00EDguez-Mach\\u00EDn

    2014-01-01

    Full Text Available El panorama energético de la biomasa va tomando un mayor auge ante el vaticinado agotamiento de los combustibles fósiles, el impacto ambiental que representa y la seguridad energética asociada. El presente trabajo se desarrolla en la Unidad Empresarial de Base (UEB Héctor Rodríguez. Esta unidad emplea el bagazo obtenido en el proceso industrial de producción de azúcar para la generación de calor y de electricidad sin estimar adecuadamente su potencial. El propósito de esta investigación es aplicar las ecuaciones matemáticas para la estimación de la biomasa herbácea potencial al caso de la biomasa cañera (bagazo y conocer su disponibilidad con fines energéticos. Se aplicó el método de evaluación con relación residuo producto (RRP, el valor calculado está dentro del rango de los reportados en la literatura, pero fue preciso emplear el RRP calculado para el país por ser este más representativo que el calculado para la UEB. Se estimó que la biomasa potencial en central azucarero entre 2007 y 2012 fue de 98 856 t de bagazo. El potencial bruto máximo fue de 3 222 MW-h/día, lo cual permite establecer el límite superior a alcanzar en cuanto a potencial de biomasa se refiere en el proceso industrial pero no tiene en cuenta la totalidad de la caña producida en el proceso agrícola.

  7. Electron Paramagnetic Resonance Studies of Cu2+ and VO2+ Spin Probes in RO-Li2O-Na2O-K2O-B2O3 (R = Zn, Mg, Sr and Ba Glass Systems

    Directory of Open Access Journals (Sweden)

    Abdul Hameed

    2012-01-01

    Full Text Available Mixed alkali and alkaline earth oxide glasses of RO-Li2O-Na2O-K2O-B2O3(R = Zn, Mg, Sr and Ba system were studied by electron paramagnetic resonance (EPR and optical absorption spectroscopy. Cu2+ and VO2+ ions were used as the spin probes. The glasses containing 1 mole% of Cu2+ and 2mole% of VO2+ were prepared by the melt quenching method. X-ray diffraction studies of the samples did not reveal crystalline phases. EPR measurements were made at X-band frequencies with 100 kHz field modulation, at 310 K. Optical spectra were recorded in the wavelength range 300 nm - 800 nm. From the EPR spectra the spin-Hamiltonian parameters were evaluated. The spin-Hamiltonian parameter values in the case of Cu2+ indicated that the ground state of Cu2+ was orbital (2B1g and the site symmetry around Cu2+ is tetragonally distorted octahedral. The variation of gll and All with the alkaline earth oxide (RO composition was found to be non-linear which may be due to the change in the ligand field strength at the site of Cu2+ ions. From the spin-Hamiltonian parameters of VO2+, it was observed that the vanadyl ions exist as VO2+ ions in octahedral coordination with tetragonal compression and have C4V symmetry with ground state dxy. Tetragonality (?gll/?g of V4+ ion sites exhibited non-linear variation with RO content, which indicated change in the ligand field at the site of V4+. A broad optical absorption band was observed in the glass containing Cu2+ ions corresponding to the 2B1g ? 2B2g transition. From the EPR and optical data the bond parameters were evaluated. In the case of VO2+ ions, the covalency rates were estimated.

  8. Accessing the VO with Python

    Science.gov (United States)

    Plante, R.; Fitzpatrick, M.; Graham, M.; Tody, D.; Young, W.

    2014-05-01

    We introduce two products for accessing the VO from Python: PyVO and VOClient. PyVO is built on the widely-used Astropy package and is well suited for integrating automated access to astronomical data into highly customizable scripts and applications for data analysis in Python. VOClient is built on a collection of C-libraries and is well suited for integrating with multi-language analysis packages. It also provides a framework for integrating legacy software into the Python environment. In this demo, we will run through several examples demonstrate basic data discovery and retrieval of data. This includes finding archives containing data of interest (VO registry), retrieving datasets (SIA, SSA), and exploring (Cone Search, SLAP). VOClient features some extended capabilities including the ability to communicate to other desktop applications from a script using the SAMP protocol.

  9. Selective formation of VO2(A) or VO2(R) polymorph by controlling the hydrothermal pressure

    International Nuclear Information System (INIS)

    Missing VO2(A) usually occurs during the preparation of VO2 polymorphs. This leads to an ambiguous understanding of the transformation between VO2 polymorphs. The calculation of the ground state energies for different VO2 polymorphs indicated that there is only a small energy gap between VO2(A) and VO2(R), which destined that the transformation from VO2(A) to VO2(R) should be pressure sensitive. This hypothesis was verified during the synthesizing of VO2 polymorphs by reducing V2O5 with oxalic acid through hydrothermal treatment process. Selective formation of pure phase VO2(A) or VO2(R) was achieved by controlling the hydrothermal pressure through varying the filling ratio at 270 deg. C. It was found that a filling ratio over 0.5 favors the formation of pure VO2(R) while a reduced filling ratio to 0.4 or lower results in the formation of VO2(A). Based on our experiments, VO2(B) nanobelts were always first formed and then it transformed to VO2(A) by assembling process at increased temperature or extended reaction time. Under further higher pressure, the VO2(A) transformed spontaneously to VO2(R) initialized from the volume shrinkage due to the formation of denser VO2(R). - Graphical abstract: Selective formation of VO2(A) or VO2(Rn of VO2(A) or VO2(R) could be achieved by controlling the system pressure through varying the filling ratio during hydrothermal treatment. Highlights: ? Selective formation of VO2 polymorphs by controlling hydrothermal pressure. ? Ground state energy characteristics were revealed for the first time. ? Phase transformation mechanism was clearly elucidated.

  10. VO2máx estimado e sua velocidade correspondente predizem o desempenho de corredores amadores / Estimated VO2max and its corresponding velocity predict performance of amateur runners

    Scientific Electronic Library Online (English)

    Tony Meireles, Santos; Allan Inoue, Rodrigues; Camila Coelho, Greco; Alan Lima, Marques; Bruno Souza, Terra; Bruno Ribeiro Ramalho, Oliveira.

    Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in portuguese Observa-se, nos últimos anos, um importante crescimento do número de praticantes de corrida com proporcional aumento da adesão destes às provas de rua. Nesta população, a identificação dos determinantes do desempenho parece ser necessária para otimização do tempo dedicado ao treinamento. O objetivo [...] do estudo foi estabelecer a associação do consumo máximo de oxigênio (VO2máx) estimado, da velocidade crítica (VC) e da velocidade do VO2máx (V VO2máx), com os desempenhos nas provas de 3,6 km em subida e 10 e 21,1 km no plano. Doze corredores amadores (9 homens) com 36 ± 5 anos de idade foram submetidos a quatro testes: 1 e 5 km de corrida, no plano; 3,6 km de corrida, com inclinação (?8%); e um teste para determinação indireta do VO2máx. A VC foi determinada através da relação linear entre a distância e o tempo de corrida dos dois primeiros testes. Os sujeitos participaram de duas provas oficiais de 10 km e 21,1 km. A V VO2máx foi estimada a partir do VO2máx, através de equações metabólicas. O VO2máx apresentou a melhor associação com o desempenho da corrida em 10 e 21,1 km no plano. Já na subida, a V VO2máx apresentou melhor associação. Considerando todas as provas, a variável com maior média associativa foi o VO2máx (0,91±0,07), seguido do V VO2máx (0,90±0,04) e VC (0,87±0,06), respectivamente. Este estudo demonstrou elevadas associações entre variáveis fisiológicas estabelecidas por métodos indiretos, de baixo investimento e alta praticidade, com o desempenho da corrida em 10 e 21,1 km, no plano, e 3,6 km, em subida. Abstract in english In recent years, there has been a substantial increase in the number of runners, with a proportional increase in their involvement in amateur street competition. Identification of the determinants of performance in this population appears necessary for optimization of time devoted to training. The o [...] bjective of this study was to ascertain the association between estimated maximal oxygen uptake (VO2max), critical velocity (CV) and VO2max velocity (V VO2max) and athletic performance in the 3.6 km (uphill) and 10 and 21.1 km (flatland) events. Twelve amateur runners (nine male), mean age 36 ± 5 years underwent five tests: 1 and 5 km race on level ground, 3.6 km race with slope (?8%), and indirect VO2max measurement. CV was determined from the linear relationship between distance and run time on the first two tests. The subjects then took part in two official 10 km and 21.1 km (half marathon) races. V VO2max was calculated from the VO2max through a metabolic equation. VO2max showed the best association with running performance in the 10 and 21.1 km events. For the uphill race, V VO2max showed a better association. Overall, the variable with the highest average association was VO2max (0.91±0.07), followed by V VO2max (0.90±0.04) and VC (0.87±0.06). This study showed strong associations between physiological variables established by low-cost, user-friendly indirect methods and running performance in the 10 and 21.1 km (flatland) and 3.6 km (uphill) running events.

  11. Basal renal O2 consumption and the efficiency of O2 utilization for Na+ reabsorption.

    Science.gov (United States)

    Evans, Roger G; Harrop, Gerard K; Ngo, Jennifer P; Ow, Connie P C; O'Connor, Paul M

    2014-03-01

    We examined how the presence of a fixed level of basal renal O2 consumption (Vo2(basal); O2 used for processes independent of Na(+) transport) confounds the utility of the ratio of Na(+) reabsorption (TNa(+)) to total renal Vo2 (Vo2(total)) as an index of the efficiency of O2 utilization for TNa(+). We performed a systematic review and additional experiments in anesthetized rabbits to obtain the best possible estimate of the fractional contribution of Vo2(basal) to Vo2(total) under physiological conditions (basal percent renal Vo2). Estimates of basal percent renal Vo2 from 24 studies varied from 0% to 81.5%. Basal percent renal Vo2 varied with the fractional excretion of Na(+) (FENa(+)) in the 14 studies in which FENa(+) was measured under control conditions. Linear regression analysis predicted a basal percent renal Vo2 of 12.7-16.5% when FENa(+) = 1% (r(2) = 0.48, P = 0.001). Experimentally induced changes in TNa(+) altered TNa(+)/Vo2(total) in a manner consistent with theoretical predictions. We conclude that, because Vo2(basal) represents a significant proportion of Vo2(total), TNa(+)/Vo2(total) can change markedly when TNa(+) itself changes. Therefore, caution should be taken when TNa(+)/Vo2(total) is interpreted as a measure of the efficiency of O2 utilization for TNa(+), particularly under experimental conditions where TNa(+) or Vo2(total) changes. PMID:24431201

  12. Biomasa, rendimiento, eficiencia en el uso del agua y nitrógeno en girasol de humedad residual

    Directory of Open Access Journals (Sweden)

    J. Alberto Escalante Estrada

    2001-01-01

    Full Text Available Durante 1987 y 1988, se realizó un estudio para determinar la influencia genotípica y de la fertilización nitrogenada (150 y 300 kg N ha-1 sobre la producción de biomasa, rendimiento y eficiencia en el uso del agua (EUA del girasol (Helianthus annuus L., cultivado en condiciones de humedad residual. Los resultados indican que las condiciones ambientales variaron principalmente con relación a la precipitación, que fue de 531 mm y de 709 mm. Esto influyó sobre la producción del girasol, la cual en ambos años mostró diferencias genotípicas y diferente respuesta a la aplicación de N. Sungro 380 (genotipo tardío mostró mayor producción de biomasa, un índice de cosecha y rendimiento más bajo que Arbung E-353 (ABE353, genotipo precoz, en particular en el año más seco. En 1987, el N incrementó la biomasa en 17 y 29% y el rendimiento en 14 y 12% en ABE353 y Sungro 380, respectivamente. En 1988, el incremento en biomasa fue 76 y 64%, y de 51 y 29% en rendimiento de grano para los genotipos respectivos. Dichos incrementos fueron producto de una mayor EUA. Para lograr una mayor producción de girasol en estas regiones, se recomienda la siembra de genotipos precoces y fertilización nitrogenada.

  13. MODELOS MATEMÁTICOS PARA LA ESTIMACIÓN DE BIOMASA DE ÓRGANOS AÉREOS DE LIMÓN 'PERSA' (Citrus latifolia Tan.

    Directory of Open Access Journals (Sweden)

    L. A. Crespo-Herrera

    2007-01-01

    Full Text Available En muchos de los estudios de crecimiento de las plantas se requiere evaluar la biomasa, lo cual normalmente implica la destrucción de los árboles. En el presente trabajo se generaron modelos matemáticos de alta confiabilidad que estiman la cantidad de biomasa de órganos aéreos de limón 'Persa' con base en otras variables que no requieren la destrucción del material vegetal y además son de fácil medición. Para ello, se separaron ramas, hojas y frutos de los árboles y se les midió la cantidad de biomasa además del área foliar de las hojas y otras características morfológicas inherentes a cada tipo de órgano. Se encontró que la cantidad de biomasa de cada órgano se encuentra estrechamente relacionada con las siguientes características: para las ramas, el volumen calculado por las fórmulas del cono y cono truncado, en los casos de las ramas no podadas y podadas, respectivamente; para los frutos, el diámetro ecuatorial, y para las hojas, la longitud de la lámina y su ancho máximo. Se generaron modelos para cada órgano con coeficientes de determinación muy elevados (entre 0.9528 y 0.9981 y C(p aceptable (entre 1.6696 y 16.3685, para modelos de 2 a 4 variables.

  14. Neutron diffraction studies of CeVO/sub 4/,PrVO/sub 4/, and ScVO/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    Faber, J. Jr.; Aldred, A.T.

    1982-01-01

    High resolution neutron powder diffraction studies (T = 300 K) have been carried out on CeVO/sub 4/, PrVO/sub 4/, and ScVO/sub 4/. Bond distance determinations show that although the rare earth ion size varies over a wide range, the characteristic V-O distance remains the same. The rare-earth-oxygen distances, however, approach an isotropic configuration with increasing rare earth ion size.

  15. Vo?by 2012

    Directory of Open Access Journals (Sweden)

    Mikuláš Huba

    2011-12-01

    Full Text Available Vážení a milí, priatelia a priate?ky,žijeme v postmodernej dobe, v ktorej sa dá zdôvodni?, ale aj spochybni? prakticky všetko.Aj preto je nám jasné, že môžete vznies? sto argumentov proti nasej kandidatúre i proti tomu, že sme sa ocitli práve na listine tohto politického subjektu. A budete ma? svojím spôsobom pravdu. Ubezpe?ujeme Vás, že tých „100 argumentov proti“ sme zvažovali i my, ale napokon prevážilo tých 101 za. Vlastne sme mali len dve iné možnosti: nekandidova? vôbec, alebo sa pokúša? dosta? na kandidátku niektorej zo strán. Málokedy za uplynulých 22 rokov bolo u nás znechutenie politikou, sklamanie a nutkanie rezignova? silnejšie, ako práve teraz. Ale práve preto sa nám zdá, že je potrebné nerezignova? a prekona? prirodzený odpor k tomuto kroku.

  16. Electron Paramagnetic Resonance Studies of Cu<sup>2+</sup> and VO<sup>2+</sup> Spin Probes in RO-Li<sub>2</sub>O-Na<sub>2</sub>O-K<sub>2</sub>O-B<sub>2</sub>O<sub>3</sub> (R = Zn, Mg, Sr and Ba) Glass Systems

    OpenAIRE

    Abdul Hameed; Gokarakonda Ramadevudu; Siddey Laksmisrinivasa Rao; Mohmmad Shareefuddin; Mudumba Narasimha Chary

    2012-01-01

    Mixed alkali and alkaline earth oxide glasses of RO-Li2O-Na2O-K2O-B2O3(R = Zn, Mg, Sr and Ba) system were studied by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Cu2+ and VO2+ ions were used as the spin probes. The glasses containing 1 mole% of Cu2+ and 2mole% of VO2+<...

  17. Biorefinery Technologies for Biomass Conversion Into Chemicals and Fuels Towards Zero Emissions (Review) / Nulles Emisiju Princips Biomasas Konversijas Tehnolo?ij?s Aizst?jot Fosilos Resursus (P?rskata Raksts)

    Science.gov (United States)

    Gravitis, J.; Abolins, J.

    2013-10-01

    Exhausting of world resources, increasing pollution, and climate change are compelling the shift of the world economy from continuous growth to a kind of economy based on integration of technologies into zero emissions production systems. Transition from non-renewable fossil resources to renewable resources provided by solar radiation and the current processes in biosphere is seen in the bio-refinery approach - replacing crude oil refineries by biomass refineries. Biotechnology and nano-technologies are getting accepted as important players along with conventional biomass refinery technologies. Systems design is a significant element in the integration of bio-refinery technologies in clusters. A number of case-studies, steam explosion auto-hydrolysis (SEA) in particular, are reviewed to demonstrate conversion of biomass into value-added chemicals and fuels. Analysis of energy flows is made as part of modelling the SEA processes, the eMergy (energy memory) approach and sustainability indices being applied to assess environmental impacts. Resursu izs?kums, vides pies?r?ojums un glob?la m?roga klimatisk?s izmai?as ir civiliz?cijas izdz?vošanai b?tiski faktori, kas virza pasaules ekonomikas p?rmai?as, atsakoties no nep?rtrauktas izaugsmes idejas par labu t?dai ekonomikai, kas balst?s uz atjaunojošamies resursiem un daž?du tehnolo?iju integr?cijemisiju principam atbilstoš?s ražošanas sist?m?s. Saules radi?cijas ierosin?tajos plan?tas biosf?r? notiekošajos procesos rad?to organisko vielu p?rstr?des kompleksi, kas oper? iev?rojot sabalans?tu nulles emisiju principu, tiek uzl?koti k? t?s ekonomisk?s (ražošanas) strukt?ras, kur?m j?nodrošina p?reja uz atjaunojošos resursu izmantošanu, aizst?jot esoš?s fosilo resursu (naftas, og?u) p?rstr?des r?pn?cas. L?dz?s jau apg?taj?m biomasas rafin?šanas tehnolo?ij?m svar?ga un pieaugoša loma ekonomisk?s sist?mas resursu b?zes nomai?? ir bio- un nanotehnolo?ij?m, bet ražošanas sist?mu projekt?šanai - biomasas konversijas tehnolo?iju klasteriz?cij?. Apl?kojot virkni konkr?tu tehnolo?isko risin?jumu, TSA - biomasas autohidrol?zi tvaika spr?dzien? tai skait?, iztirz?tas ar biomasas konversiju, izmantošanu un augstas pievienot?s v?rt?bas produktiem - ??miskiem savienojumiem un degviel?m, saist?t?s ekololo?isk?s un energoefektivit?tes probl?mas. Uzsverot biomasas TSA pirmapstr?des univers?lo noz?mi daž?do tehnolo?isko kompleksu strukt?r?, apl?kota TSA ietekme uz vidi, demonstr?jot eMer?ijas (ener??tisk?s atmi?as) pieeju un „ilgtsp?jas" indeksu izmantošanu. Lai gan pie sasniegt? tehnolo?isk?s att?st?bas l?me?a un patreiz?jiem fosilo ener?ijas nes?ju pat?ri?a tempiem nav iesp?jams tos piln?b? aizst?t ar bioener?iju, bioener?ijas sektora tehnolo?iju pilnveidošana ir svar?ga ar? bioresursu racion?las izmantošanas un citos aspektos. Latvijas ener??tisk?s neatkar?bas kontekst? b?tiska noz?me ir tradicion?lo bioener?ijas resursu izmantošanas efektivit?tes celšanai un inovat?vo bioener?ijas tehnolo?iju valstiskam atbalstam.u nulles

  18. EFECTO DEL ÁCIDO SALICÍLICO SOBRE BIOMASA, ACTIVIDAD FOTOSINTÉTICA, CONTENIDO NUTRICIONAL Y PRODUCTIVIDAD DEL CHILE JALAPEÑO

    Directory of Open Access Journals (Sweden)

    Esteban S\\u00E1nchez-Ch\\u00E1vez

    2011-01-01

    Full Text Available El uso de biorreguladores del crecimiento es una práctica para mejorar el rendimiento y calidad de los cultivos. Actualmente se ha considerado al ácido salicílico un biorregulador del crecimiento de las plantas. El objetivo del presente trabajo fue estudiar el efecto de las diferentes dosis de ácido salicílico (AS sobre la acumulación de biomasa, concentración de pigmentos, actividad fotosintética, contenido nutricional y productividad del chile jalapeño (Capsicum annuum L. cv. Chichimeca. El AS fue aplicado a la solución nutritiva en dosis crecientes: 0.025 mM, 0.05 mM, 0.1 mM, 0.2 mM, 0.4 mM y 0.8 mM, más un control (sin aplicación de AS. Los resultados indican que la aplicación de AS a las plantas de chile jalapeño cv. Chichimeca aumentaron significativamente la producción de biomasa foliar, en raíz y total, principalmente en las dosis de 0.1 y 0.2 mM. Por otro lado, los tratamientos de 0.1 y 0.2 mM de AS tuvieron un efecto positivo en la producción de frutos. Asimismo, la actividad fotosintética presentó un comportamiento similar a la acumulación de biomasa y producción de frutos por planta, sobresaliendo los tratamientos 0.1 y 0.2 mM de AS con la máxima actividad fotosintética. En relación al análisis nutricional, se observó que a una mayor acumulación de biomasa y producción por planta se presentó una menor acumulación de nutrientes, debido probablemente al efecto de dilución. Se concluye que los tratamientos con 0.1 y 0.2 mM de AS cumplen un papel de biorregulador del crecimiento en chile jalapeño.

  19. DISTRIBUCIÓN DE BIOMASA Y ACUMULACIÓN DE PLOMO EN CALABACITA (Cucurbita pepo L. CULTIVADA EN SUELO CONTAMINADO

    Directory of Open Access Journals (Sweden)

    Floriberto Solis-Mendoza

    2012-01-01

    Full Text Available Se estudió el efecto del suelo contaminado con plomo en el híbrido experimental de calabacita (Cucurbita pepo L. denominado 'Termo'. Se cultivó calabacita en bolsas negras de polietileno, a cielo abierto. Se evaluaron las variables distribución de la producción de biomasa, altura de planta, contenido de clorofila y acumulación de plomo en raíz, tallo, hoja, flor y fruto. Los tratamientos fueron 0, 65, 300 y 1000 ppm de plomo aplicado al suelo a través de Pb(NO32. Se utilizó un diseño experimental de bloques completos al azar con seis repeticiones, y la unidad experimental fue una bolsa negra de polietileno con dos plantas. Las evaluaciones se hicieron 50 días después del trasplante para altura de planta y contenido de clorofila, y a los 52 días para peso fresco, peso seco y acumulación de plomo. Se observó que la altura de planta fue significativamente menor cuando se aplicó plomo a cualquier dosis. También se observó que la mayor acumulación de biomasa en raíz y tallo fue producida con la dosis 300 ppm y en fruto con 65 ppm de plomo, en tanto que la biomasa total y las unidades SPAD (clorofila no resultaron afectadas. De las estructuras comestibles, la flor presentó una mayor acumulación del metal que el fruto. A bajas dosis de plomo, la flor fue la estructura que más lo acumuló. Esto sugiere que es conveniente evaluar el contenido de metales pesados en productos agrícolas para consumo humano, aun cuando provengan de suelos contaminados sin intención.

  20. Biomasa acumulada e indicadores de calidad nutritiva en cebadilla chaqueña (Bromus auleticus Trinius ex Nees)

    Scientific Electronic Library Online (English)

    E.G.R, Bustamante; M.A, Ruiz; E, Morici; F.J, Babinec; A.B, Pordomingo.

    2012-12-01

    Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish Bromus auleticus (cebadilla chaqueña) es considerada uno de los recursos forrajeros más promisorios del Cono Sur. Presenta variación entre poblaciones que ha sido determinada para diversos caracteres vegetativos, lo cual podría traducirse en diferencias de producción y calidad de forraje. El objetiv [...] o del presente estudio fue evaluar dos procedencias de cebadilla chaqueña (Argentina y Uruguay) para biomasa acumulada e indicadores de calidad nutritiva en dos períodos del año (verano-otoño y otoño-primavera). Se compararon cinco clones uruguayos (U) y cinco argentinos (A), dispuestos al azar en surcos distanciados a 1 m entre sí, con 10 plantas cada uno. Se determinó biomasa acumulada por planta (B) y calidad, midiendo Fibra Detergente Neutra (FDN), Proteína Bruta (PB) y Digestibilidad de la Materia Seca (DMS) en dos momentos del año. En general, la biomasa fue de baja calidad debido al momento en que se realizaron los cortes, lo que limita el alcance de los resultados. Sin embargo, las diferencias observadas entre los clones en este estado de desarrollo podrían indicar la existencia de variación entre genotipos de cebadilla chaqueña U y A en biomasa y calidad nutritiva. En biomasa acumulada no se observó efecto significativo de origen. En todas las variables de calidad evaluadas en verano-otoño, se encontraron diferencias significativas entre orígenes. En otoñoprimavera, las diferencias entre orígenes fueron significativas para DMS. Los clones U presentaron mayor PB, menor FDN y mayor DMS. Dentro de cada origen, los argentinos presentaron menos diferencias que los uruguayos, tanto en biomasa acumulada como en calidad. Para ninguno de los clones A o U se encontró coincidencia entre mayor biomasa y mayor calidad. Abstract in english Bromus auleticus (“chaqueña” bromegrass) may be considered as one of the most valuable forage species for the Southern Cone. This species shows variation among populations, determined in diverse vegetative characters, which could result in differences in production and forage quality. The objective [...] of this study was to evaluate two origins of Bromus auleticus (Argentina and Uruguay) for characters of biomass accumulated and quality in two periods of the year (Summer-Autumn and Autumn-Spring). Five Uruguayan (U) and Argentine (A) clones were compared, it were randomly arranged in rows spaced one meter of each other, with 10 plants each one. Biomass accumulated per plant (B) and biomass quality were determined in two times of the year measuring neutral detergent fiber (NDF), crude protein (CP) and dry mater digestibility (DMD). In general, quality of biomass was poor due to time cuttings, limiting the scope of the results. However, differences between the clones in this stage of development could be indicating the presence of variation among genotypes of “chaqueña” prairie grass U and A in biomass and nutritional quality. Significant effect of origin for B was not observed. In all biomass quality variables evaluated in Summer-Autumn, significant differences between origins were found. In Autumn-Spring, differences between origins were significant in DMD. U clones showed more CP, less NDF and higher DMD. Within each origin, A showed less differences than U both in B and quality. Concerning A or U clones, no coincidence between high biomass and high quality was found.

  1. VO2 films as active infrared shutters

    OpenAIRE

    Johansson, Daniel

    2006-01-01

    An active optical shutter for infrared light (3-5 ?m) has been designed, exploiting the phase transition in thermochromic vanadium dioxide (VO2). A spin coating processing route for VO2 films has been adapted to manufacture reproducible depositions onto sapphire (Al2O3) substrates. The VO2 films have been characterized by X-ray powder diffraction (XRPD) and infrared spectroscopy (FTIR), showing 55 % transmittance in the open mode and 0.1 % in the closed mode. The VO2 film temperature determi...

  2. Hydrothermal Synthesis and Photocatalytic Properties of Cu-doped BiVO4 Microsheets

    Directory of Open Access Journals (Sweden)

    LIU Guo-Cong, JING Zhen, ZHANG Xi-Bing, LI Xian-Feng, LIU Hong

    2013-03-01

    Full Text Available Using Bi(NO33·5H2O, NaVO3 and Cu(NO32·3H2O as raw materials, Cu-doped BiVO4 microsheets were synthesized by ultrasonic-hydrothermal process with cetyltrimethyl ammonium bromide (CTAB as template. The as-prepared samples were investigated by XRD, XPS, SEM, HRTEM, UV-Vis and BET tests. The results reveal that uniform and well crystallized Cu/BiVO4 microsheets in monoclinic crystal structure, with length of 1.0–2.0 ?m, width of 0.5–2.0 ?m and thickness of 200–300 nm, could be obtained via an ultrasonic-hydrothermal route assisted by 2.0 g CTAB. Compared with BiVO4 particles, Cu/BiVO4 nanosheets show a little red shift in the absorption band, resulting in a narrowed band gap (<2.4 eV. For 5.0wt% Cu/ BiVO4 microsheet, its photodegradation rate constant K is5.89 ×10–2 /min and the best photocatalytic activity is found with a 100% degradation of methylene blue (MB with 10 mg/L concentration under visible-light irradiation for 60 min.

  3. New phases in the system LiMnVO4-Mn3(VO4)2

    International Nuclear Information System (INIS)

    The synthesis of orthorhombic Mn3(VO4)2 via a simple solid state route as well as the description of a new tetragonal high temperature phase are reported in this paper. Additionally, the system LiMnVO4-Mn3(VO4)2 (=Mn1.5VO4), described by the formula LixMn1.5-x/2VO4, is investigated in detail, showing that substitution of one Mn2+ in Mn1.5VO4 by two Li+ ions favors the formation of the tetragonal high temperature phase for x?0.22. This substitution is facilitated by the statistical half occupancy of the 4b site by Mn2+ in tetragonal Mn1.5VO4, whereas additional crystallographic sites would have to be occupied in the orthorhombic phase. The inverse substitution of Li by Mn in orthorhombic LiMnVO4 is also shown to be possible in the range 0.72?x?1. For 0.22?x?0.72, there is a large miscibility gap with a two phase mixture of the tetragonal Mn1.5VO4 type and orthorhombic LiMnVO4 type phases. - Graphical Abstract: The unusual coordination of Mn in the form of a stella quadrangula with the surrounding vanadate groups. Highlights: ? First synthesis of orthorhombic Mn3(VO4)2 via a simple solid state route. ? The crystal chemistry of the phases involved is rather complicated and it s rather complicated and it depends on the amount of Li that is incorporated. ? System LiMnVO4-Mn3(VO4)2 (=Mn1.5VO4), described by the formula LixMn1.5-x/2VO4, is investigated in detail.

  4. Efecto de nutrientes sobre la producción de biomasa del hongo medicinal Ganoderma lucidum

    Directory of Open Access Journals (Sweden)

    Ana María Torres López

    2011-04-01

    Full Text Available  Effect of nutrients in the biomass production of the medicinal mushroom Ganoderma lucidum Título corto: Efecto de nutrientes sobre la producción de G. lucidumResumen El hongo Ganoderma lucidum, en los constituyentes de su biomasa, tiene compuestos con propiedades benéficas para la salud; es por esto que el conocimiento de las condiciones nutricionales adecuadas para su crecimiento permitirá su producción industrial y a bajo costo. En este trabajo se evaluó a nivel de matraz el efecto de la relación C/N, y la presencia de diferentes fuentes de carbono, nitrógeno y micronutrientes sobre la producción de biomasa. Empleando glucosa y peptona como fuentes de carbono y nitrógeno, respectivamente, se encontró una relación C/N óptima de 16,7:1 para la cual la máxima producción de biomasa fue de 25 g/L. Manteniendo esta relación C/N, y sustituyendo la glucosa por lactosa o harina de cebada y la peptona por extracto de levadura, la producción de biomasa se incrementó a 35 g/L. En presencia de harina de cebada la adición al medio de cultivo de sales de Mg y K, y de tiamina, no generó un mayor incremento en la producción de biomasa. La producción de biomasa de G. lucidum se ve favorecida por la presencia en el medio de cultivo de relaciones C/N cercanas a las reportadas conforme a la composición típica de los hongos, así como por la presencia de sustratos complejos como la harina de cebada que le aportan además de la fuente de carbono micronutrientes necesarios para su desarrollo. Palabras clave: harina de cebada, relación C/N, micronutrientes, fuentes de carbono, fuentes de nitrógeno.  AbstractGanoderma lucidum fungus has some biomass components with beneficial health properties. The knowledge about its nutritionals requirements for growing will favor its industrial production at lower cost. In this work, the effect of C/N ratio, the presence of different carbon, nitrogen and micronutrients sources, on fungal biomass production, were evaluated. Using glucose and peptone as carbon and nitrogen sources, respectively, an optimal C/N ratio of 16,7:1 was found, for which the maximal biomass production was 25 g/L. Replacing glucose by lactose or barley flour and peptone by yeast extract at the same C/N ratio, the biomass production was enhanced to 35 g/L. With barley flour in the culture medium, the presence of Mg and K salts and thiamine did not turn out into a major increase of biomass. The G. lucidum biomass production is promoted by C/N ratios in the culture medium nearly equivalent to that found in the fungus, as well as the presence of complex substrates as barley flour which, additionally, contributes with important micronutrients along with the carbon source.  Key words: Barley flour, C/N ratio, micronutrients, carbon sources, nitrogen sources.

  5. Security in VoIP

    OpenAIRE

    Gerea, Floriana

    2012-01-01

    VoIP relies on packet switching, similar to the way that e-mails are sent over the Internet. The technology breaks down a voice call into bite-size information packets. Instead of keeping the switch open all the time, the information is sent and received as needed, allowing excess line capacity to be used to carry other data. When the voice data arrives at its destination, it's reassembled into a voice call. As voice over IP services grow in popularity, the potential for viruses, worms and ot...

  6. Factores del manejo para estabilizar la producción de biomasa con leguminosas en el trópico

    Directory of Open Access Journals (Sweden)

    T. E. Ruiz

    2006-01-01

    Full Text Available Este material tiene como objetivo abundar acerca de aquellos factores del manejo que conduzcan a estabilizar la producción de biomasa en sistemas ganaderos en el trópico. Es obvio que los sistemas mejorados y bien manejados de pasturas de gramíneas y leguminosas, en cualquiera de sus alternativas, son opciones para lograr la sostenibilidad. Una concepción más amplia y profunda es la relativa a los estudios de pasturas mixtas; éstos, deben tener un enfoque más biológico por lo que, además de considerar el ambiente en el cual se desarrollan y crecen, hay que incluir la forma en que los componentes vegetales se manifiestan en las especies implicadas del agroecosistema. Aquí no podemos olvidar el efecto del animal. Los problemas asociados con la persistencia se reconocen cada vez más como una preocupación real. Los diversos factores que controlan la permanencia de las especies forrajeras se agrupan en aquellos que pueden ser manejados y controlados por el productor, así como en los que éste no puede intervenir. Es por ello que las producciones animales y de otro tipo, derivados de estos sistemas, varían positivamente en el tiempo, en la medida en que se va consolidando la relación suelo /planta /animal. De esta correspondencia no puede quedar excluido el papel interactuante y modificador del hombre con los elementos antes señalados. La producción de biomasa es una actividad multidisciplinaria; de ahí que el éxito de su funcionamiento esté condicionado al conocimiento de las interacciones entre sus componentes, así como entre éstos y el medio ambiente, lo cual permitirá la generación de estrategias de manejo acordes con la ecología que conduzcan a mejorar la productividad y la sostenibilidad del agroecosistema. Por tanto, la producción de biomasa constituye un elemento determinante en el éxito y la eficiencia de los sistemas con leguminosas.

  7. Produccion de Biomasa de Scenedesmus Obliquus en diferentes medios de cultivo.

    Directory of Open Access Journals (Sweden)

    V. Mart\\u00EDnez

    2005-01-01

    Full Text Available Los nutrientes son factores fundamentales que afectan el rendimiento de los cultivos de microalgas, de ahí la importancia de llevar a cabo estudios a escala de laboratorio con cepas de interés científico y comercial. El objetivo del trabajo fue investigar la producción de biomasa de Scenedesmus obliquus en diferentes medios de cultivo. Se utilizaron dos reactores tipo columnas de 2 L de capacidad empleando medio Extracto de Suelo, y medio Albañal Sintético respectivamente, a los cuales se les adicionó el inóculo del cultivo (1%, en la fase logarítmica de crecimiento. Para mantener agitado y homogéneo el sistema, se suministró aire a razón de 100 L/h, que fue medido con un regulador de flujo y se colocaron en un local cuya temperatura media era de 29,7 o C. Los reactores trabajaron en modo discontinuo (batch. Se mantuvieron con un régimen de luz/oscuridad de 8/16 horas durante 18 días. Para seguir el comportamiento del cultivo se determinó la Densidad óptica, la clorofila a, los sólidos suspendidos volátiles, se midió el pH y la producción de biomasa en el sistema. La velocidad de crecimiento específico fue ¿ = 0,16 d-1 para el cultivo en el medio Agar extracto de suelo y ¿ = 0,33 d-1 para el cultivo en medio Albañal sintético. El tiempo de duplicación fue de 4,33 d'-1 para el cultivo en medio AES y 2,10 d-1 para el medio de Albañal Sintético. Se alcanzaron los valores más altos en la producción de biomasa en el medio Albañal, lo que demostró un mejor desarrollo de la microalga investigada en este medio.

  8. Phase relations and optoelectronic characteristics in the NdVO4–BiVO4 system

    International Nuclear Information System (INIS)

    Studies performed on the NdVO4–BiVO4 system showed the existence of the BixNd1?xVO4 homogeneity range for x ? 0.49(1). Extended X-ray absorption fine structure and X-ray diffraction analyses confirmed that Bi3+ is incorporated onto the Nd site in the NdVO4 crystal structure with some distortion of the local structure. Surprisingly, the unit cell volume decreases with the increase in the content of the larger Bi3+ ion. On the other side of the NdVO4–BiVO4 system, Nd3+ does not enter the BiVO4 structure but forms the NdVO4-based secondary phase. Ultraviolet–visible spectroscopy showed that the band gap of NdVO4 can be reduced to below 3.1 eV by the Bi doping. New emissions that do not exist for NdVO4 have been found in the 650–675 nm range of BixNd1?xVO4 photoluminescence spectra. The observed chemical and optoelectronic properties were explained on the basis of the hybridization of Bi 6s2 and O 2p orbitals

  9. Recuperación de la biomasa mediante la sucesión secundaria, Cordillera Central de los Andes, Colombia

    Scientific Electronic Library Online (English)

    Jorge Ignacio, del Valle; Héctor Iván, Restrepo; Mónica María, Londoño.

    1337-13-01

    Full Text Available SciELO Costa Rica | Language: Spanish Abstract in spanish En bosques secundarios premontanos tropicales es escasa la información sobre el tiempo requerido para recuperar la biomasa aérea y subterránea de los primarios. Por lo tanto, establecimos 33 parcelas de 0.1ha entre 550 y 1 700m en bosques secundarios que cubrían estadios serales de 3 a 36 años y est [...] imamos la biomasa de las plantas y de las raíces gruesas con ecuaciones locales. Así como la biomasa de las pasturas y barbechos por cosecha de 54 y 18 parcelas, respectivamente. También se calculó la edad de las parcelas con informantes locales, sensores remotos, C14 y anillos de crecimiento. En cada parcela medimos la biomasa aérea viva por hectárea (Bav) y la de las raíces gruesas por hectárea (Brg). Modelamos la Bav y Brg en función de la edad mediante la ecuación de von Bertalanfy con asíntotas de 247t/ha (Bav) y 66t/ha (Brg) resultantes de la medición de 33 parcelas de 0.1ha en los bosques primarios. Con la razón Brg/Bav=f(t) estimamos 87 años para que los bosques secundarios recuperen la Bav existente en los primarios y 217 años para recuperar la Brg. La tasa máxima de crecimiento instantáneo de la Bav fue 6.95t/ha/año a los 10 años y la tasa media máxima de crecimiento 6.26t/ha/año a los 17 años. La media ponderada de la tasa de crecimiento absoluto de la Bav alcanzó 4.57t/ha/año y la relativa 10% anual. La razón Brg/Bav inicialmente aumenta muy aceleradamente hasta 4-5 años (25%), luego disminuye hasta 25 años (18%) para luego incrementar hasta 26.7 Abstract in english Biomass recovery through secondary succession in the Cordillera Central de los Andes, Colombia. Estimations on biomass recovery rates by secondary tropical forests are needed to understand the complex tropical succession, and their importance on CO2 capture, to offset the warming of the planet. We c [...] onducted the study in the Porce River Canyon between 550 and 1 700m.a.s.l. covering tropical and premontane moist belts. We established 33 temporary plots of 50mx20m in secondary forests, including fallows to succesional forests, and ranging between 3 and 36 years old; we measured the diameter at breast height (D) of all woody plants with D?5cm. In each one of these plots we established five 10mx10m subplots, in which we measured the diameter betweem 1cm?D

  10. CONCENTRACIÓN DE CARBONO EN LA BIOMASA AÉREA DEL MATORRAL ESPINOSO TAMAULIPECO

    Directory of Open Access Journals (Sweden)

    Jos\\u00E9 I. Yerena-Yamallel

    2011-01-01

    Full Text Available Se determinó la concentración de carbono por unidad de biomasa base peso seco de 10 especies del matorral espinoso tamaulipeco y para cada uno de sus componentes (tallo, ramas, ramillas, hojas y corteza. La concentración de carbono expresado como porcentaje de la biomasa, se hizo con el equipo Solids TOC Analyzer, que determina la concentración de carbono en muestras sólidas a través de combustión completa. Mediante un ANAVA no se encontraron diferencias en la concentración promedio de carbono de las especies (P>0.05; esta concentración varió de 44.25 a 47.08 % con una media general de 45.4±1.32 %; Cordia boissieri (44.25±1.52 % y Acacia farnesiana (44.52±1.37 % son las especies que resultaron con los valores de concentración de carbono menores, y Forestiera angustifolia (47.08±1.27 % con el más alto. El componente corteza de Cordia boissieri obtuvo el menor porcentaje de concentración de carbono (39.62±0.70 %, y las hojas de Acacia schaffneri el mayor (50.14±1.21 %; la interacción de ambos factores resultó significativa (P<0.0001.

  11. Biomasa aérea, cantidad y calidad de semilla de Melinis repens (Willd. Zizka, en Aguascalientes, México

    Directory of Open Access Journals (Sweden)

    Abraham D\\u00EDaz Romo

    2012-01-01

    manualmente forraje y semilla. Se determinó la producción de forraje, producción de espiguillas y número de semillas por metro cuadrado. Se valoró la viabilidad, germinación y latencia de la semilla a diferentes tiempos después de la cosecha. La producción de biomasa aérea difirió (P<0.05 con promedios de 2913 a 1736 kg MS ha-1 en 2008 y de 1488 a 707 kg MS ha-1 en 2009 (menos lluvioso, con mayor producción en Calvillo. La producción de semillas varió (P<0.05 de 1,239 a 2,401 semillas m2 en 2008 y de 1,452 a 3,906 semillas m2 en 2009. La viabilidad en la semilla fue de 32 a 54 %, sin diferencias significativas. Calvillo presentó mayor germinación (25 %, la cual fue aumentando y a los 18 meses casi toda la semilla viable germinó (43 %. En El Llano la germinación fue menor (2 % debido a la latencia, con poco aumento aún después de 24 meses, llegando a 15 %. Este pasto presentó niveles altos de producción de biomasa aérea y semilla, lo que puede favorecer su capacidad invasora, aunque también puede ser una ventaja para la conservación de suelos. La semilla presentó mayor producción y latencia en condiciones de escasez de agua.

  12. Análisis Exergético de la Gasificación de Biomasa Exergy Analysis of Biomass Gasification

    Directory of Open Access Journals (Sweden)

    Jorge M Mendoza

    2012-01-01

    Full Text Available El objetivo de este estudio fue realizar el análisis exergético de la gasificación de biomasa residual con la finalidad de obtener energía útil. Se desarrolló un modelo para la gasificación de biomasa basado en el equilibrio químico de las reacciones. Este modelo permite predecir la evolución de la composición del gas de síntesis en función de la temperatura, las presiones y la composición elemental de los residuos del proceso de extracción de aceite de palma y orujo de lavado de uva (hidrogeno, oxigeno, carbono y nitrógeno, como también hacer un análisis exergético. Se encontró que independiente del agente gasificante, la concentración de monóxido de carbono e hidrógeno tienden a incrementar significativamente a altas presiones y elevadas temperaturas. Además, se muestra que la eficiencia exergética incrementa con la temperatura y disminuye con el aumento de la relación aire/combustible.This paper shows the exergy analysis applied to the gasification process of residual biomass with the purpose of obtaining useful energy. A model for the biomass gasification based on chemical equilibrium of the reactions is proposed. The model allows predicting the syngas composition as a function of temperature, pressure and ultimate analysis of palm oil and grapevine pruning waste (determining hydrogen, oxygen, carbon and nitrogen. It was found that the carbon monoxide and hydrogen concentration significantly increase at high pressure and temperature independently of the gasifying agent. Furthermore, it was also noticed that the exergy efficiency increases as temperature increases, and decreases as the relative fuel/air ratio increases.

  13. Thermal capacity of FeVO4, CrVO4 and AlVO4 at low temperatures

    International Nuclear Information System (INIS)

    Thermal capacity of orthovanadates of iron, chromium and aluminium in the 3-80 K temperature range is investigated. The conclusion is drawn on magnetic nature of the observed anomaly on temperature dependence thermal capacity of FeVO4 and CrVO4. The anomaly of thermal capacity on temperature dependence of AlVO4 thermal capacity is related to the Schottky effect arising because of the presence in the sample of rather small quantity of V4+ paramagnetic ions which appear at the vanadates synthesis in the air (Po2=2.1x104 Pa)

  14. The Na2O-CaO-V2O5 system with 0-50 mol. % V2O5

    International Nuclear Information System (INIS)

    The data on binary and ternary oxide compounds related to the Na2O-CaO-V2O5 system in the area of Na2O-NaV3-Ca(VO3)2-CaO are studied. Formation of sodium vanadates NaVO3, Na5V3O10, Na3VO4 and calcium vanadates Ca(VO3)2, Ca2V2O7, Ca3(VO4)2, Ca7V4O17, binary vanadates Na2Ca(VO3)4, Na3Ca2V3O11, NaCaVO4, NaCa4(VO4)2 and solid solution on the ?-Ca3(VO4)2 basis is confirmed. Formation of Ca4V2O9, Ca5V2O10, Na2CaV2O7 and Na4C12(V2O7)7 is not confirmed. Formation of the binary pyrovanadate of the Na2Ca-(V2O7)4 composition is established. The IR-spectra are studied for five vanadates. Elementary three-component systems in the area under consideration are identified and the phase diagram for subsolidus temperatures is plotted

  15. COMPUTER SIMULATION IN THE ELECTRONICS EDUCATION FOCUSED TO INCREASE THE SPECIAL HIGH SCHOOL STUDENTS MOTIVATION II. / Po?íta?ové modelovanie vo výu?be elektroniky zamerané na zvýšenie motivácie žiakov SOŠ II

    Directory of Open Access Journals (Sweden)

    Arpáš Július

    2008-02-01

    Full Text Available The authors interpret the particular results of their research in this contribution. It is focused to the impact of computer model on education. Anticipated result is the higher efficiency of special education here. This aim is achieved by application of motivation relations in coherence with exploitation easy reached free software. At the same time here is the latest technology, based on the computer design of circuits, applied here.Tento príspevok je pokra?ovaním prvej ?asti, ktorá bola zameraná na zvýšenie motivácie prostredníctvom bezplatne získate?ného softvéruzo siete internet. Obsahom druhej ?asti príspevku je súbor ukážok jednosmernej, striedavej a transiert analýzy elektronických obvodov.

  16. Comprehensive Comparison of VoIP SIP Protocol Problems and Cisco VoIP System

    Directory of Open Access Journals (Sweden)

    TALAL AL-KHAROBI

    2012-08-01

    Full Text Available Voice over IP (VoIP, use of the packet switched internet for telephony, has improved substantially in the past few years. On the other hand, VoIP has many challenges that do not exist in the public switched telephone network (PSTN, a circuit switched system. VoIP is an application running on the internet, and therefore inherits the internet’s security issues. It is important to realise that VoIP is a relatively young technology, and with any new technology, security typically improves with maturity. This paper provides a comprehensive comparison of a VoIP SIP protocol and CISCO VoIP system. The comparison involves the investigation of the vulnerabilities that target both systems and how secure each system is. With this comparison we present our conclusion on which system is more secure.

  17. Nanostructured WO3 /BiVO4 photoanodes for efficient photoelectrochemical water splitting.

    Science.gov (United States)

    Pihosh, Yuriy; Turkevych, Ivan; Mawatari, Kazuma; Asai, Tomohiro; Hisatomi, Takashi; Uemura, Jin; Tosa, Masahiro; Shimamura, Kiyoshi; Kubota, Jun; Domen, Kazunari; Kitamori, Takehiko

    2014-09-24

    Nanostructured photoanodes based on well-separated and vertically oriented WO3 nanorods capped with extremely thin BiVO4 absorber layers are fabricated by the combination of Glancing Angle Deposition and normal physical sputtering techniques. The optimized WO3 -NRs/BiVO4 photoanode modified with Co-Pi oxygen evolution co-catalyst shows remarkably stable photocurrents of 3.2 and 5.1 mA/cm(2) at 1.23 V versus a reversible hydrogen electrode in a stable Na2 SO4 electrolyte under simulated solar light at the standard 1 Sun and concentrated 2 Suns illumination, respectively. The photocurrent enhancement is attributed to the faster charge separation in the electronically thin BiVO4 layer and significantly reduced charge recombination. The enhanced light trapping in the nanostructured WO3 -NRs/BiVO4 photoanode effectively increases the optical thickness of the BiVO4 layer and results in efficient absorption of the incident light. PMID:24863862

  18. Estimación de la biomasa aérea de seis leguminosas leñosas del Chaco Árido (Argentina)

    Scientific Electronic Library Online (English)

    María del Rosario, Iglesias; Alicia Haydée, Barchuk.

    2010-04-01

    Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish La posibilidad de contar con estimaciones confiables de la biomasa aérea de la vegetación leñosa resulta imprescindible para el manejo productivo, la conservación o la restauración de los ecosistemas de bosque. Sin embargo, no siempre se dispone de técnicas relativamente sencillas y no destructivas. [...] Este trabajo presenta modelos de regresión para estimar la biomasa aérea total de seis especies arbustivas y arbóreas de la familia Fabaceae, nativas del Chaco Árido (Prosopis flexuosa, Geoffroea decorticans, Cercidium praecox, Acacia furcatispina, Mimoziganthus carinatus y Prosopis torquata). Los modelos incluyeron distintas combinaciones del diámetro a la base (DAB) y la altura de los individuos. Todos ellos predijeron aceptablemente la biomasa por especie, si bien el de regresión lineal que utiliza el DAB² como variable independiente presentó el mejor ajuste. Las especies fueron agrupadas según sus rasgos comunes en: monopódicas de madera dura, multitallares de madera extremadamente pesada, monopódica de madera excesivamente pesada y monopódica y multitallar de madera extremadamente pesada y para cada uno de los grupos se generó una ecuación. Abstract in english Reliable estimates of biomass for the vegetation of the Arid Chaco forest is critical for its management, conservation or restoration. However, simple and non destructive techniques are not largely available. This study provides regression models aimed at estimating the aerial biomass of native shru [...] b and tree species from the Arid Chaco, belonging to the Fabaceae family (Prosopis flexuosa, Geoffroea decorticans, Cercidium praecox, Acacia furcatispina, Mimoziganthus carinatus and Prosopis torquata). An additional objective was to explore the feasibility of using a single equation for several species. The wood density differed significantly between species. Linear and nonlinear regression models of aerial biomass were adjusted for species, with different combinations of base diameter (DAB) and height as independent variables. The models properly predicted the biomass by species, the most appropriate being the linear regression model using DAB² as an independent variable. To establish differences in the behavior of species and, more precisely, in the ratio between total dry weight and DAB, the slope homogeneity was analyzed using a regression model with auxiliary variables. Taking into account the results obtained and the basic wood density and morphological growth structure, four groups of species have been postulated, and it was feasible to apply a single equation per group. The proposed groups are: (1) monopodial hardwood (Geoffroea decorticans and Cercidium praecox), (2) multi-stem shrubs of extremely heavy wood (Acacia furcatispina and Mimoziganthus carinatus), (3) monopodial of very heavy wood (Prosopis flexuosa) and (4) monopodial and multi-stem of extremely heavy wood (Prosopis torquata).

  19. Revisión sobre la corrosión de tubos sobrecalentadores en plantas de biomasa

    Directory of Open Access Journals (Sweden)

    Berlanga-Labari, C.

    2006-08-01

    Full Text Available The design of new biomass-fired power plants with increased steam temperature raises concerns of high-temperature corrosion. The high potassium and chlorine contents in many biomasses, specially in wheat straw, are potentially harmful elements with regard to corrosion. Chlorine may cause accelerated corrosion resulting in increased oxidation, metal wastage, internal attack, void formations, and loose non-adherent scales. The most severe corrosion problems in biomass-fired systems are expected to occur due to Cl-rich deposits formed on superheater tubes. In the first part of this revision the corrosion mechanism proposed are described in function of the conditions and compounds involved. The second part is focused on the behaviour of the materials tested so far in the boiler and in the laboratory. First the traditional commercial alloys are studied and secondly the new alloys and the coatings

    En el diseño de plantas de biomasa es muy importante tener en cuenta la temperatura del vapor para no tener problemas de corrosión. Esto, es debido al alto contenido de potasio y cloro que tienen la mayoría de los biocombustibles y, en especial, la paja de cereal. El objetivo de esta revisión es condensar el conocimiento actual sobre la corrosión de los sobrecalentadores a altas temperaturas provocada por compuestos clorados en plantas de biomasa. El cloro puede causar corrosión acelerada debido a la pérdida de metal del sobrecalentador, ataque interno y formación de capas de óxidos no adherentes. Los problemas de corrosión más severos en una caldera de biomasa se producen en los depósitos formados sobre los tubos sobrecalentadores. En la primera parte de esta revisión, se describen los mecanismos de corrosión propuestos en función de las condiciones de trabajo predominantes en la caldera. La segunda parte, se centra en revisar los estudios realizados para comprobar el comportamiento de los materiales mediante ensayos realizados en la caldera y en el laboratorio. En primer lugar, se describen las investigaciones realizadas sobre aleaciones convencionales y después las realizadas sobre las aleaciones desarrolladas en los últimos años y recubrimientos.

  20. Performance Evaluation for VoIP on Campus

    Directory of Open Access Journals (Sweden)

    Rendy Munadi

    2013-09-01

    Full Text Available The VoIP Campus implementation is to make the existing VoIP technology become more beneficial for campus stake holder. This VoIP on Campus (VoC technology make use of a web server, facilitating users to carry out VoIP registration, get and changing account, and also to see others who have register and active in this VoIP network. Basically, this VoC infrastructure uses asterisk as VoIP server and playVoIP as web server interface, those programs included in a server computer. Furthermore, the server interconnected with several servers, such as, PBX, SMS gateway, ENUM server, softphone and smartphone. At this moment, VoC network serve locally, but next time it will be developed so that it could be served in public network, and further VoC network could be connected to VoIP Rakyat, the biggest VoIP network in Indonesia. In this research, VoC network have been tested for several QoS parameters, such as throughput, delay, jitter, packet loss, and MOS. Average value for each parameter, are : 27 kbps throughput, 20.08 ms delay, 3.54 ms jitter, 0.08% packet loss, and 3.3 MOS. Those results  indicates that VoC network have a good performance.  

  1. Proceso de gasificación de biomasa: una revisión de estudios teórico- experimentales / Biomass gasification process: theoretical and experimental studies a review

    Scientific Electronic Library Online (English)

    Juan, Pérez; David, Borge; John, Agudelo.

    2010-03-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish La situación energética y medioambiental mundial hace que la generación de energía mediante sistemas basados en energías renovables tome cada vez una mayor relevancia. Estos sistemas tienen una doble ventaja ya que posibilitan la diversificación energética y reducen la dependencia del petróleo a la [...] vez que se disminuyen las emisiones globales de CO2. La biomasa es uno de los recursos energéticos con mayor potencial tanto en países desarrollados como emergentes pero sigue sin sufrir el desarrollo esperado. La gasificación de biomasa es uno de los sistemas con gran potencial ya que permite la generación tanto de energía térmica como eléctrica, mediante tecnologías de bajo costo como los gasificadores de lecho fijo (potencias medias- bajas), o reactores de lecho fluidizado con tecnología más exigente y con mayor capacidad de generación. La transformación de la biomasa en un combustible gaseoso, aprovechable en motores de combustión interna alternativos o en turbinas de gas como combustible, exige que la biomasa atraviese varios procesos termoquímicos, compuestos por reacciones endotérmicas (secado, devolatilización y reducción) y exotérmicas (oxidación de volátiles y carbón). La selección de un gasificador requiere conocer las propiedades de la biomasa, mientras que el diseño del mismo exige conocer el fenómeno termoquímico por completo. El objetivo de este trabajo es presentar una revisión actualizada de los diferentes planteamientos tanto teóricos como experimentales desarrollados para estudiar el proceso de gasificación de biomasa, tanto en lecho fijo como en lecho fluidizado, con miras a diseñar gasificadores de biomasa. Abstract in english Each day the energy systems relying on renewable resources are more relevant in the world energy politics due to the fossil energy and environmental crisis. These systems increase energy resources of countries, reduce the oil dependency, and diminish CO2 global emissions. Biomass is one of the renew [...] able resources with higher potential in developing and developed countries. Biomass gasification has huge possibilities to be developed. Such as fixed bed gasifiers, or fluidized bed reactors with more technology demanding and more power capacity. Biomass transformation in a gaseous fuel to be used in a reciprocating internal combustion engine or gas turbines requires that biomass passes through several thermochemical stages. Endothermic reactions (drying, pyrolysis and reduction) and exothermic process (volatiles and carbon oxidation). To select a specific gasifier it is necessary to know biomass properties (chemical and physical), whereas to design a reactor it is necessary to know and understand the complete phenomena. The aim of this work is to show an actualized review about different theoretical and experimental approaches to study biomass gaification process in fixed and fluidized bed reactors in order to design biomass gasifiers.

  2. Bioadsorción de Cadmio (II en Solución Acuosa por Biomasas Fúngicas Biosorption of Cadmium (II in Aqueous Solutions by Fungal Biomass

    Directory of Open Access Journals (Sweden)

    Ismael Acosta

    2007-01-01

    Full Text Available Se determinó la bioadsorción de Cadmio (II en solución por la biomasa celular de quince hongos, por el método colorimétrico de la ditizona. La biomasa de Mucor rouxii IM-80 fue más eficiente en la remoción de Cadmio (II en solución (8.2 mg/g seguida de M. rouxii mutante (7.1 mg/g, A. flavus I (5.9 mg/g y Helminthosporium sp (5.4 mg/g. Para la biomasa de M. rouxii-IM-80, la mayor bioadsorción fue a pH= 5.0-6.0, a 28ºC durante 40 horas con 1.0 mg/200 mL de concentración inicial de Cadmio (II y 80 mg/200 mL de biomasa celular. Se concluye que algunas biomasas fúngicas remueven eficientemente Cadmio (II en solución y pueden utilizarse para descontaminar nichos acuáticos contaminados con este metalThe biosorption of dissolved Cadmium (II using cellular biomass of 15 fungi, using a dithizone colorimetric method, was determined. The Mucor rouxii IM-80 biomass was more efficient in removing Cadmium (II from solution (8.2 mg/g, followed by the M. rouxii mutant (7.1 mg/g, Aspergillus flavus I (5.9 mg/g and Helminthosporium sp (5.4 mg/g biomasses. The highest biosorption for M. rouxii IM-80 was at pH 5.0-6.0, at 28ºC for 40 h employing 1.0 mg/200mL of Cadmium (II as initial concentration, and 80 mg/200 mL of fungal biomass. It was concluded that some fungal biomass efficiently removed Cadmium (II from solution and could be used for decontamination of aquatic habitats polluted with this metal

  3. Análisis Exergético de la Gasificación de Biomasa / Exergy Analysis of Biomass Gasification

    Scientific Electronic Library Online (English)

    Jorge M, Mendoza; Antonio J, Bula; Rafael D, Gómez; Lesmes A, Corredor.

    Full Text Available SciELO Chile | Language: Spanish Abstract in spanish El objetivo de este estudio fue realizar el análisis exergético de la gasificación de biomasa residual con la finalidad de obtener energía útil. Se desarrolló un modelo para la gasificación de biomasa basado en el equilibrio químico de las reacciones. Este modelo permite predecir la evolución de la [...] composición del gas de síntesis en función de la temperatura, las presiones y la composición elemental de los residuos del proceso de extracción de aceite de palma y orujo de lavado de uva (hidrogeno, oxigeno, carbono y nitrógeno), como también hacer un análisis exergético. Se encontró que independiente del agente gasificante, la concentración de monóxido de carbono e hidrógeno tienden a incrementar significativamente a altas presiones y elevadas temperaturas. Además, se muestra que la eficiencia exergética incrementa con la temperatura y disminuye con el aumento de la relación aire/combustible. Abstract in english This paper shows the exergy analysis applied to the gasification process of residual biomass with the purpose of obtaining useful energy. A model for the biomass gasification based on chemical equilibrium of the reactions is proposed. The model allows predicting the syngas composition as a function [...] of temperature, pressure and ultimate analysis of palm oil and grapevine pruning waste (determining hydrogen, oxygen, carbon and nitrogen). It was found that the carbon monoxide and hydrogen concentration significantly increase at high pressure and temperature independently of the gasifying agent. Furthermore, it was also noticed that the exergy efficiency increases as temperature increases, and decreases as the relative fuel/air ratio increases.

  4. VO2+ and Cu2+ Interactions with Ceftriaxone and Ceftizoxime. HPLC Kinetic Studies

    Scientific Electronic Library Online (English)

    Antonio L., Doadrio; Antonio, Mayorga; Regina, Orenga.

    2002-02-01

    Full Text Available SciELO Brazil | Language: English Abstract in portuguese Estudos do mecanismo, das constantes cinéticas e termodinâmicas das interações de VO2+ e Cu2+ com Ceftriaxone e Ceftizoxime, na faixa de pH entre 2 e 5 e nas temperaturas de 30 º,40 º, 50 º e 60 ºC, usando HPLC em fase reversa e de troca iônica são descritos. Foram avaliados os efeitos de pH, temper [...] atura e concentração dos íons na reação de hidrólise. Estudos de HPLC forneceram evidência satisfatória do mecanismo da reação. Mecanismos das reaçôes dos complexes de Cu2+ e VO2+ envolvem um complexo 1:1. Abstract in english Studies of the mechanism, kinetics and thermodynamic constants of VO2+ and Cu2+ Ceftriaxone and Ceftizoxime interactions at the pH range between pH 2 and 5 and at the temperatures of 30 º, 40 º, 50 º and 60 ºC, using reversed phase HPLC and ion exchange HPLC, are reported. The effects of pH, tempera [...] ture and ion concentration on the hydrolysis reaction have been evaluated. HPLC studies provided satisfactory evidence of the reaction mechanism. Mechanisms for Cu2+ and VO2+ induced reactions involve a complex of 1:1 stoichiometry.

  5. Electron paramagnetic resonance and optical absorption study of VO2+-doped sodium zinc sulfate tetrahydrate single crystals

    Science.gov (United States)

    Kripal, Ram; Shukla, Santwana

    2012-01-01

    Single-crystal electron paramagnetic resonance (EPR) studies of VO2+ doped in sodium zinc sulfate tetrahydrate (Na2Zn(SO4)2·4H2O) have been carried out at room temperature. The results show the presence of three magnetically inequivalent VO2+ sites with different populations. The VO2+ impurity ions take up substitutional positions in the host lattice replacing Zn2+ ions. The angular variation of EPR spectra in three mutually orthogonal planes, bc, a*c and ba*, are used to determine the spin-Hamiltonian parameters. The optical absorption spectrum of VO2+ ions doped in the crystal lattice is also recorded at room temperature in the wavelength range 325-1100 nm. This is utilized to study the energy level structure of the VO2+ ion. By correlating the EPR and optical data, various molecular orbital coefficients of the VO2+ ion with its ligands are evaluated and the nature of bonding in the crystal is discussed.

  6. VO2 Kinetics and Metabolic Contributions Whilst Swimming at 95, 100, and 105% of the Velocity at VO2?max

    OpenAIRE

    Sousa, Ana C.; Vilas-boas, Joa?o P.; Fernandes, Ricardo J.

    2014-01-01

    A bioenergetical analysis of swimming at intensities near competitive distances is inexistent. It was aimed to compare the transient VO2 kinetics responses and metabolic contributions whilst swimming at different velocities around VO2max?. 12 trained male swimmers performed (i) an incremental protocol to determine the velocity at VO2max? (vVO2max?) and (ii) three square wave exercises from rest to 95, 100, and 105% of vVO2max?. VO2 was directly measured using a telemetric portable gas...

  7. Producción de biomasa y utilización de Leucaena leucocephala fertilizada y pastoreada por ovinos

    Scientific Electronic Library Online (English)

    Selina, Camacaro; Wilfre, Machado.

    2005-04-01

    Full Text Available Un experimento de campo fue realizado en la sección de ovinos de la Facultad de Agronomía de la Universidad Central de Venezuela, ubicado en Maracay, estado Aragua para evaluar el efecto de la fertilización con S, Cu y Zn sobre la producción de biomasa Leucaena leucocephala y su utilización por ovin [...] os a pastoreo. Se utilizó una asociación de la leguminosa sembrada en hileras sencillas de 1 x 4 m, en un potrero de Cynodon plectostachyous. Se usó un diseño de bloques al azar con tres repeticiones, utilizando ocho tratamientos que incluyeron un testigo negativo (sin fertilización), un testigo positivo (S, Cu y Zn) y los seis restantes con un elemento faltante. Se hicieron cuatro muestreos destructivos y no destructivos; los primeros se realizaron sobre 10 plantas, evaluando altura promedio, número de ramas, longitud de tallos con Ø 6 mm, número de hojas, longitud de hojas, materia seca de hojas (MSH), materia seca de tallos con Ø 6 mm (MST>) para generar ecuaciones de regresión y estimar la producción de biomasa. Para los muestreos no destructivos, se evaluaron las mismas variables mencionadas anteriormente con excepción de las de materia seca. Hubo diferencias (P y la participación de la MST0,05). La utilización de L. leucocephala no fue afectada (P>0,05) por los tratamientos. Los resultados indican que bajo estas condiciones, la aplicación de S de L. leucocephala aumenta la producción de biomasa, pero no afecta su utilización por ovinos a pastoreo. Abstract in english A field experiment was carried out in the Sheep Section of the Faculty of Agronomy of the Central University of Venezuela, located in Maracay, Aragua state to evaluate the effect of the fertilization of Leucaena leucocephala on the biomass production and its utilization for grazing sheep. An associa [...] tion of the legume already sown in single rows of 1x4 m, on a pasture of Cynodon plectostachyous, was used. An aleatory block design was used with three repetitions, including a negative control (without fertilization) and a positive control (S, Cu, and Zn) and the six remaining treatments with a missing element. Four destructive and non destructive samplings were made; the first was made on 10 plants, evaluating height, number of branches, length of branches Ø 6 mm, number of leaves, length of leaves, dry matter of leaves, dry matter of branches Ø 6 mm. For the non destructive samplings, except for dry matter, the same variables were evaluated. There were differences (P and the % of participation of the MST 0.05). The utilization of the L. leucocephala was not affected (P>0.05) by the treatments. The results indicated that under these conditions, the fertilization of L. leucocephala increased the biomass production, but it did not affect its utilization by grazing sheep.

  8. VO2 max in an Indian population: a study to understand the role of factors determining VO2 max.

    Science.gov (United States)

    Nitin, Y M; Sucharita, S; Madhura, M; Thomas, T; Sandhya, T A

    2013-01-01

    VO2 max is the maximum amount of oxygen a person can consume and the value does not change despite an increase in workload. There is lack of data evaluating the impact of factors, which could affect VO2 max measurement, particularly in Indian population. The objectives of the present study were (i) to estimate VO2 max in a young healthy Indian population and to compare it with available prediction equations for Indian population (ii) to correlate time to achieve VO2 max with the relative VO2 max (iii) to assess the factors affecting the time to achieve VO2 max measurement (body composition and physical activity level). Twenty healthy adult males (18-30 years) underwent detailed anthropometry, physical activity level and modified Bruce protocol for VO2 max assessment. Breath by breath VO2, VCO2, oxygen saturation, heart rate, blood pressure were measured continuously and following exercise protocol. There was an internal validity between the estimated VO2 max and the maximum heart rate (MHR) (r = 0.51, P < 0.05). Respiratory rate and tidal volume significantly correlated with VO2 max P < 0.01). Linear regression analysis indicated physical activity level (PAL) was a strong predictor of time to reach VO2 max. Out of the 3 prediction equations computed to estimate VO2 max, 2 equations significantly overestimated VO2 max. In Conclusion, physical activity level emerged to be a strong predictor of time to VO2 max. Time to achieve VO2 max is an important factor to be considered when determining VO2 max. There was an overestimation in the VO2 max values derived from predicted equations. PMID:24617157

  9. Estimativa das contribuições dos sistemas anaeróbio lático e alático durante exercícios de cargas constantes em intensidades abaixo do VO2max / Estimation of contributions of the anaerobic lactic and alactic systems during constant-load exercises at intensities below the VO2max

    Scientific Electronic Library Online (English)

    Marcos David, Silva-Cavalcante; Renata Gonçalves, Silva; Rodrigo Poles, Urso; Rogério Carvalho, Silva; Carlos Rafaell, Correia-Oliveira; Victor Gustavo Ferreira, Santos; Adriano Eduardo, Lima-Silva; Rômulo, Bertuzzi.

    2013-06-01

    Full Text Available O objetivo do estudo foi estimar as contribuições do metabolismo anaeróbio lático (MAL) e alático (MAA) em intensidades abaixo do consumo máximo de oxigênio (VO2max). Dez homens (23 ± 4 anos, 176,4 ± 6,8 cm, 72,4 ± 8,2 kg, 12,0 ± 4,5 % de gordura corporal) realizaram um teste progressivo até a exaus [...] tão voluntária para identificação do VO2max, da potência correspondente ao VO2max (WVO2max) e do segundo limiar ventilatório (LV2). Na segunda e na terceira visita foram realizados seis testes de cargas constantes (três testes por sessão) com intensidades abaixo do VO2max. Houve uma predominância do MAL sobre o MAA durante os exercícios submáximos a partir da intensidade correspondente ao LV2, sendo significativamente maior em 90% VO2max (p Abstract in english The purpose this study was that estimated contributions of the anaerobic lactic (MAL) and alactic (MAA) metabolism during constant load exercises at intensities below the maximal oxygen capacity uptake (VO2max). Ten males (23 ± 4 years, 176.4 ± 6.8 cm, 72.4 ± 8.2 kg, 12.0 ± 4.5 % of fat body) perfor [...] med in the first visit a progressive test until exhaustion to identification of VO2max, power output corresponding to the VO2max (WVO2max) and second ventilatory threshold (LV2). On the second and third visit, the participants performed six constant workload tests (3 per session) with intensities below VO2max. There was a predominance of MAL about MAA during the exercises sub-maximal from intensity corresponding to the LV2, being significantly higher at 90% VO2max (p

  10. Drowning in Data : VO to the rescue

    CERN Document Server

    Lawrence, A

    2009-01-01

    Astronomical datasets are growing in size and diversity, posing severe technical problems. At the same time scientific goals increasingly require the analysis of very large amounts of data, and data from multiple archives. The Virtual Observatory (VO) initiative aims to make multiwavelength science and large database science as seamless as possible. It can be seen as the latest stage of a long term trend towards standardisation and collectivisation in astronomy. Within this inevitable trend, we can avoid the high energy style of building large fixed hierarchical teams, and keep the individualist style of astronomical research, if the VO is used to build a facility class data infrastructure. I describe how the VO works and how it may change in the Web 2.0 era.

  11. Control de una planta prototipo de gasificación de biomasa mediante redes neuronales

    Scientific Electronic Library Online (English)

    Carlos A., Forero Núñez; José U., Castellanos Contreras; Fabio E., Sierra Vargas.

    Full Text Available Los sistemas de gasificación de Biomasa son una alternativa para emplear residuos agroindustriales y generar un combustible gaseoso; sin embargo, estos procesos no lineales se ven afectados por las características típicas del material y por la variación en las temperaturas al interior del equipo, po [...] r lo tanto se requieren sistemas de control para alcanzar estados estables en el tiempo. Este trabajo analiza el desempeño de un control mediante redes neuronales aplicado a un gasificador de lecho fijo corriente descendente cuando se emplean cascaras de coco o cuesco de palma. Los resultados indican que el uso del sistema de control en el equipo, alimentado con cascaras de coco, permite aumentar las temperaturas en el reactor de 600°C a 800°C en la zona de inyección, superando así el problema derivado de la baja transferencia de energía por conducción a través del sistema. Cuando se emplea el control en la gasificación de cuesco, la temperatura promedio se mantuvo constante en 790°C, el CO presente en el gas estuvo alrededor de 10% mientras que el CO2 disminuyó a 4%. La aplicación de un sistema de control mediante redes neuronales es una gran alternativa puesto que se puede entrenar para cada tipo de biomasa mejorando la estabilidad del sistema y produciendo un gas de síntesis con menor contenido de CO2. Esto para un país con gran diversidad de recursos agroindustriales abre la posibilidad de usar estos subproductos en la generación de energía a partir de fuentes renovables. Abstract in english The gasification power systems are a remarkable alternative because they can use agro-industrial wastes to produce clean syngas; although, the differences between the biomass properties and the inner temperatures throughout the equipment make compulsory the use of control systems to achieve stable s [...] tates. This work aims to analyze the effect of applying a Neural Network Control System on a Downdraft fixed bed gasifier fed with Coconut shells and Oil Palm shells. Results show that the use of the control system on the equipment fed with coconut shells increased the maximum temperature at the air injection zone from 600°C to 800°C, which overcomes the problems found by the low thermal conductivity of the coconut shells. With the control system and the equipment fed with oil palm shells, the maximum temperature was 790°C; the CO in the syngas was stable at 10%, whereas the CO2 decreased to 4%. The Neural Network control system is useful because this can be trained for each biomass, resulting on stable temperatures and low CO2 syngas. This improves the chances of producing energy from renewable resources in a country with a lot of agro-industrial byproducts like Colombia.

  12. Effect of high-intensity interval training and detraining on extra VO2 and on the VO2 slow component.

    Science.gov (United States)

    Marles, A; Legrand, R; Blondel, N; Mucci, P; Betbeder, D; Prieur, F

    2007-04-01

    To examine the effect of 6-week of high-intensity interval training (HIT) and of 6-week of detraining on the VO2/Work Rate (WR) relationship and on the slow component of VO2, nine young male adults performed on cycle ergometer, before, after training and after detraining, an incremental exercise (IE), and a 6-min constant work rate exercise (CWRE) above the first ventilatory threshold (VT1). For each IE, the slope and the intercept of the VO2/WR relationship were calculated with linear regression using data before VT1. The difference between VO2max measured and VO2max expected using the pre-VT1 slope was calculated (extra VO2). The difference between VO2 at 6th min and VO2 at 3rd min during CWRE (DeltaVO2(6'-3')) was also determined. HIT induced significant improvement of most of the aerobic fitness parameters while most of these parameters returned to their pre-training level after detraining. Extra VO2 during IE was reduced after training (130 +/- 100 vs. -29 +/- 175 ml min(-1), P = 0.04) and was not altered after detraining compared to post-training. DeltaVO2(6'-3') during CWRE was unchanged by training and by detraining. We found a significant correlation (r2 = 0.575, P = 0.02) between extra VO2 and DeltaVO2(6'-3') before training. These results show that an alteration of extra VO2 can occur without any change in the VO2 slow component, suggesting a possible dissociation of the two phenomena. Moreover, the fact that extra VO2 did not change after detraining could indicate that this improvement may remain after the loss of other adaptations. PMID:17221260

  13. Comparaciones entre cuatro métodos de estimación de biomasa en praderas de festuca alta

    Directory of Open Access Journals (Sweden)

    Isa\\u00EDas L\\u00F3pez-Guerrero

    2011-01-01

    Full Text Available En los experimentos de pastoreo, la masa de forraje es una medida necesaria para calcular otros atributos de la pradera, como son su crecimiento, utilización, y descomposición. El problema es que esa biomasa no se puede medir en estudios a gran escala, sólo se puede estimar usando algún método de muestreo. Cuando se submuestrea, el método de corte directo (MD ha sido aceptado como el más confiable, siempre y cuando se tomen suficientes muestras. Existen, sin embargo, métodos indirectos que pueden ser más fáciles, baratos y rápidos que el MD. En consecuencia, el objetivo de este trabajo fue comparar el MD con tres métodos indirectos para estimar la masa de forraje, el medidor de pasto por capacitancia (MC, el plato medidor de pastos (PM y la estimación visual (EV. El experimento fue conducido en seis potreros de festuca alta durante los años 2002 y 2003. Se desarrollaron ecuaciones de calibración para cada método indirecto y en cada fecha de muestreo, usando regresión lineal simple. Los coeficientes de determinación para las ecuaciones de calibración con todos los datos fueron de 0.686, 0.751, y 0.862 para MC, PM, y EV, respectivamente. Se encontraron diferencias (P<0.01 debido a método de muestreo, fecha y su interacción. Los contrastes mostraron que la masa de forraje obtenida por el MD fue sobreestimada (P<0.01 por los tres métodos indirectos.

  14. Recuperación de la biomasa mediante la sucesión secundaria, Cordillera Central de los Andes, Colombia

    Directory of Open Access Journals (Sweden)

    Jorge Ignacio del Valle

    2011-09-01

    Full Text Available En bosques secundarios premontanos tropicales es escasa la información sobre el tiempo requerido para recuperar la biomasa aérea y subterránea de los primarios. Por lo tanto, establecimos 33 parcelas de 0.1ha entre 550 y 1 700m en bosques secundarios que cubrían estadios serales de 3 a 36 años y estimamos la biomasa de las plantas y de las raíces gruesas con ecuaciones locales. Así como la biomasa de las pasturas y barbechos por cosecha de 54 y 18 parcelas, respectivamente. También se calculó la edad de las parcelas con informantes locales, sensores remotos, C14 y anillos de crecimiento. En cada parcela medimos la biomasa aérea viva por hectárea (Bav y la de las raíces gruesas por hectárea (Brg. Modelamos la Bav y Brg en función de la edad mediante la ecuación de von Bertalanfy con asíntotas de 247t/ha (Bav y 66t/ha (Brg resultantes de la medición de 33 parcelas de 0.1ha en los bosques primarios. Con la razón Brg/Bav=f(t estimamos 87 años para que los bosques secundarios recuperen la Bav existente en los primarios y 217 años para recuperar la Brg. La tasa máxima de crecimiento instantáneo de la Bav fue 6.95t/ha/año a los 10 años y la tasa media máxima de crecimiento 6.26t/ha/año a los 17 años. La media ponderada de la tasa de crecimiento absoluto de la Bav alcanzó 4.57t/ha/año y la relativa 10% anual. La razón Brg/Bav inicialmente aumenta muy aceleradamente hasta 4-5 años (25%, luego disminuye hasta 25 años (18% para luego incrementar hasta 26.7Biomass recovery through secondary succession in the Cordillera Central de los Andes, Colombia. Estimations on biomass recovery rates by secondary tropical forests are needed to understand the complex tropical succession, and their importance on CO2 capture, to offset the warming of the planet. We conducted the study in the Porce River Canyon between 550 and 1 700m.a.s.l. covering tropical and premontane moist belts. We established 33 temporary plots of 50mx20m in secondary forests, including fallows to succesional forests, and ranging between 3 and 36 years old; we measured the diameter at breast height (D of all woody plants with D?5cm. In each one of these plots we established five 10mx10m subplots, in which we measured the diameter betweem 1cm?D<5cm of all woody plants. We estimated the biomass of pastures by harvesting 54 plots of 2mx2m, and of shrubs in the fallows by harvesting the biomass in 18 plots of 5mx2m. We modeled Bav (above ground live biomass of woody plants and Brg (coarse root biomass as a function of succesional age (t with the growth model of von Bertalanffy, using 247t/ha and 66t/ha as asymptote, respectively. Besides, we modeled the ratios brg/bav=f(D and Brg/Bav=f(t. The model estimated that 87 years are required to recover the existing Bav of primary forests through secondary succession, and 217 years for the Brg of the primary forest. The maximum instantaneous growth rate of the Bav was 6.95 t/ha/yr at age 10. The maximum average growth rate of the Bav was 6.26 t/ha/yr at age 17. The weighted average of the absolute growth rate of the Bav reached 4.57t/ha/yr and the relative growth rate 10% annually. The ratio brg/bav decreases with increasing D. The ratio Brg/Bav initially increases very rapidly until age 5 (25%, then decreases to reach 25 years (18% and increases afterwards until the ratio reaches the asymptote (26.7%. Rev. Biol. Trop. 59 (3:1337-1358. Epub 2011 September 01.

  15. Estimación de Iluminación en un Fotobiorreactor Productor de Biomasa a Partir de Microalgas

    Directory of Open Access Journals (Sweden)

    Carlos Francisco Gonz\\u00E1lez Hern\\u00E1ndez

    2014-01-01

    Full Text Available En el presente trabajo se realizó el análisis de iluminación artificial para un fotobiorreactor productor de biomasa a partir de microalgas, el cual fue diseñado previamente con fines en aplicación para la producción de biocombustibles. En el análisis, se utilizó como herramienta la técnica de contornos o también conocida como método de superficie de respuesta, para lo cual se establecieron 132 puntos de intensidad luminosa distribuidos de forma simétrica a diferentes alturas del contenedor. Se realizaron dos bioensayos uno con la iluminación en la parte inferior del recipiente usando Diodos Emisores de Luz (LED’s, por sus siglas en inglés y el otro adicionando 3 lámparas fluorescentes más, situadas periféricamente a la mitad de la altura total del fotobiorreactor. Los resultados de las mediciones muestran una mejoría en el sistema de iluminac ión que favorece la reproducción continua de las microalgas, cuando se utilizó la combinación de luz emitida por LED’s y por lámparas fluorescentes. Esta combinación de sistemas de iluminación generó las condiciones para poder realizar las funciones metabólicas de las microalgas, quienes necesitan en promedio 2500 lx de forma homogénea.

  16. Vplyv pesticídov na spolo?enstvo aktinomycét vo vysokohorskej pôde.

    Czech Academy of Sciences Publication Activity Database

    Selešiová, Z.; Javoreková, S.; Krišt?fek, Václav; Chro?áková, Alica

    Bratislava : Vydavate?stvo Univerzity Komenského, 2010, s. 120-127. ISBN 978-80-223-2796-1. [Život v pôde /11./. Bratislava (SK), 26.01.2010-27.01.2010] R&D Projects: GA MŠk LC06066 Grant ostatní: SAV(SK) 1/0404/09; SAV(SK) 3/6228/08 Institutional research plan: CEZ:AV0Z60660521 Keywords : pesticides * actinomycetes * grassland Subject RIV: EH - Ecology, Behaviour

  17. Characterization of nano-InVO4 powders synthesized by the hydrothermal process on various In/V molar ratio and soaking conditions

    International Nuclear Information System (INIS)

    Various hydrothermal parameters such as the In/V ratio of starting materials, soaking time and additives were conducted to examine the resulting phase formation and particle morphology of InVO4. The possible reaction during InVO4 formation was proposed. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy and BET (Brunauer-Emmett-Teller) surface area measurement. Optical properties were investigated by UV-vis and Fourier transform infrared spectroscopy. The XRD patterns indicated a single InVO4 phase formed at the starting In/V ratio of 1/2 and In(OH)3, Na2V6O16 coexisted with InVO4 when the In/V ratio was 1/1 and 1/3, respectively. For the vanadium-rich samples (In/V = 1/3), the second phase of Na2V6O16 increased with the increasing soaking time and demonstrated significant absorption in UV-vis spectra than pure InVO4. The size and shape of InVO4 particles could be tailored from rod-like into rounded square particles by PVP additives, acting as structure-directing-agent (SDA), up to 0.3 wt%.

  18. Flujos de biomasa y estructura de un ecosistema de surgencia tropical en La Guajira, Caribe colombiano

    Scientific Electronic Library Online (English)

    Maria Isabel, Criales-Hernández; Camilo, B. García; Matthias, Wolff.

    1257-12-01

    Full Text Available SciELO Costa Rica | Language: Spanish Abstract in spanish La Guajira es un ecosistema de surgencia explotado en la costa del Caribe colombiano. Con el propósito de integrar la información disponible sobre el sistema se construyó un modelo trófico de 27 grupos funcionales usando el programa Ecopath 5.0 Beta. Se obtuvo una base cuantitativa para compararlo c [...] on otros sistemas de surgencia. La Guajira presenta una biomasa total de 68 t/km²/año, la producción primaria neta del sistema es de 1 248.51 t/km²/año y las transferencias totales del sistema son de 3 275 t/km²/año, lo que indica un ecosistema con una surgencia moderada comparada con otros sitios. Las mayores transferencias de energía se dan del nivel trófico I-II (68.93 %), aunque existe una importante proporción de flujos al detritus (32 %). Los resultados en los atributos de madurez del sistema sugieren que La Guajira es un ecosistema inmaduro debido a que la relación P/R excede a 1 y está en desarrollo debido a la baja ascendencia (33.7 %) y alta capacidad de desarrollo (66.3 %) como ocurre con otras surgencias donde se presentan valores de ascendencia entre 20 % y 35 %. Aunque los datos básicos de entrada en el modelo fueron buenos, gracias a las investigaciones que se han elaborado entre 1995 y 2000, existen algunos grupos donde no se encuentra aún información adecuada; especialmente en los valores de biomasa del fitoplancton, invertebrados, bagres, peces depredadores pelágicos, así como estimaciones de producción en invertebrados, peces depredadores pelágicos y peces pequeños pelágicos. No existe una cuantificación de las poblaciones de mamíferos y aves en el área de estudio, los cuales constituyen depredadores superiores y hacen parte esencial en sistemas de surgencia Abstract in english Biomass flow and structure of a tropical upwelling ecosystem in La Guajira, Colombian Caribbean. La Guajira is an exploited tropical upwelling ecosystem in the Colombian Caribbean coast. A trophic model of 27 functional groups was constructed using the ECOPATH 5.0 Beta software to integrate the avai [...] lable information on the ecosystem. The model allowed a comparison with other trophic flow models of upwelling ecosystems. Total system biomass (68 t/km²/year), net system production (1248.5 t/km²/year), and total system throughput (3 275 t/km²/year) make La Guajira moderate when compared with other systems. The largest amount of energy throughput is achieved from trophic level I to II (68.93 %), although an important proportion of the total flow originates from detritus (32 %). The production/respiration ratio exceeds 1, suggesting that La Guajira is an immature ecosystem and is in development, as determined by its low ascendency (33.7 %) and high development capacity (66.3 %), similar to other upwellings that have values of ascendency between 20 % and 35 %. Although the basic input data were good and covered 1995 to 2000, appropriate information is still not available on some trophic groups such as biomass (for phytoplankton, invertebrates, catfishes and pelagic predator fishes), secondary production data (invertebrates, pelagic predator fishes, and small pelagic fishes), and seabird and mammal populations, which are top trophic levels and an essential part of upwelling ecosystems. Rev. Biol. Trop. 54 (4): 1257-1282. Epub 2006 Dec. 15

  19. Patterning of epitaxial VO2 microstructures by a high-temperature lift-off process

    Science.gov (United States)

    Yamin, Tony; Havdala, Tal; Sharoni, Amos

    2014-12-01

    The growing field of oxide-electronics demands adequate fabrication methods that do not impair the material’s beneficial properties. To this end, we present a modified lift-off lithography method replacing the conventional polymer mask with an AlOx based mask. It can sustain the high-temperature and reactive gasses conditions commonly needed for oxide deposition, and is effectively wet-etched in dilute NaOH solutions. Here we demonstrate patterning of VO2 films. With its metal–insulator transition (MIT) near room temperature, it is attractive for various applications including sensors and transistors. But patterning is challenging since its properties are very sensitive to fabrication processes. We demonstrate patterning of 3 ?m wide VO2 electrodes and show they preserve the MIT magnitude and epitaxial growth of the non-patterned films. Some thinning of the VO2 is also observed. This process can be useful for patterning other materials that require harsh deposition conditions, and are resilient to low NaOH concentrations.

  20. Modular VO oriented Java EE service deployer

    Science.gov (United States)

    Molinaro, Marco; Cepparo, Francesco; De Marco, Marco; Knapic, Cristina; Apollo, Pietro; Smareglia, Riccardo

    2014-07-01

    The International Virtual Observatory Alliance (IVOA) has produced many standards and recommendations whose aim is to generate an architecture that starts from astrophysical resources, in a general sense, and ends up in deployed consumable services (that are themselves astrophysical resources). Focusing on the Data Access Layer (DAL) system architecture, that these standards define, in the last years a web based application has been developed and maintained at INAF-OATs IA2 (Italian National institute for Astrophysics - Astronomical Observatory of Trieste, Italian center of Astronomical Archives) to try to deploy and manage multiple VO (Virtual Observatory) services in a uniform way: VO-Dance. However a set of criticalities have arisen since when the VO-Dance idea has been produced, plus some major changes underwent and are undergoing at the IVOA DAL layer (and related standards): this urged IA2 to identify a new solution for its own service layer. Keeping on the basic ideas from VO-Dance (simple service configuration, service instantiation at call time and modularity) while switching to different software technologies (e.g. dismissing Java Reflection in favour of Enterprise Java Bean, EJB, based solution), the new solution has been sketched out and tested for feasibility. Here we present the results originating from this test study. The main constraints for this new project come from various fields. A better homogenized solution rising from IVOA DAL standards: for example the new DALI (Data Access Layer Interface) specification that acts as a common interface system for previous and oncoming access protocols. The need for a modular system where each component is based upon a single VO specification allowing services to rely on common capabilities instead of homogenizing them inside service components directly. The search for a scalable system that takes advantage from distributed systems. The constraints find answer in the adopted solutions hereafter sketched. The development of the new system using Java Enterprise technologies can better benefit from existing libraries to build up the single tokens implementing the IVOA standards. Each component can be built from single standards and each deployed service (i.e. service components instantiations) can consume the other components' exposed methods and services without the need of homogenizing them in dedicated libraries. Scalability can be achieved in an easier way by deploying components or sets of services on a distributed environment and using JNDI (Java Naming and Directory Interface) and RMI (Remote Method Invocation) technologies. Single service configuration will not be significantly different from the VO-Dance solution given that Java class instantiation that benefited from Java Reflection will only be moved to Java EJB pooling (and not, e.g. embedded in bundles for subsequent deployment).

  1. Evaluación de dos métodos para la estimación de biomasa arbórea a través de datos Landsat TM en Jusnajab La Laguna, Chiapas, México: estudio de caso

    Directory of Open Access Journals (Sweden)

    Jorge Escand\\u00F3n Calder\\u00F3n

    1999-01-01

    Full Text Available Se evaluaron dos métodos para estimar biomasa arbórea con apoyo en sensores remotos (LANDSAT TM. El primer método se realizó con base en una clasificación supervisada multiespectral con seis bandas Se utilizaron tipos de vegetación identificados a partir de la composición de biomasa de ¡os géneros dominantes y de la altura promedio estimada del dosel, habiéndose distinguido ocho clases de vegetación. Se obtuvo una biomasa total de 1 073 x 10 3t (902 x 10 3t a 1 220 x 10 3t En el segundo método se utilizaron índices diferenciados de vegetación (NDVI de las bandas TM4/TM3; TM4/TM5 y TM4/TM7. Se aplicó un modelo de regresión que relaciona la biomasa promedio con los valores digitales (VD de los NDVI. El modelo exponencial fue el de mejor ajuste para los tres NDVl con una p 0.01. Los valores de los NVDl fueron TM4/ TM3. R2=0 611, TM4/TM5. R2=0.671 y TM4/TM7: R2=0.676. La biomasa total estimada con cada NDVI fue de 1 164 x 10 3t (490 x 10 3t a 2 409 x 10 3t para TM4/TM3; de 515x10 3t (331 x 10 3 t a 757 x 1 0 3 t p a r a TM/TM5 y d e 726 x 1 0 3 t ( 3 9 8 x 1 0 3 t a 1 210 x 10 3t para TM4/TM7. El resultado de la biomasa total calculada por el método de clasificación multiespectral, comparado con los valores estimados por el método de ordenamiento exponencial, mostró mayor similitud con el valor máximo del NDVl que relaciona las bandas TM4/TM7 (de mayor ajuste estadístico y con el valor promedio del NDVl TM4/TM3 (de menor ajuste estadístico. Utilizando el NDVl TM4/TM5, todos los valores de biomasa resultaron más bajos. De este estudio se concluye que es posible asociar razonablemente la biomasa de vegetación arbolada de pino-encino y reservorios de carbono con los índices de vegetación. A través del uso de sensores remotos se podrían predecir cambios de biomasa en escalas temporales y espaciales.

  2. Partición de biomasa aérea en procedencias de Pinus greggii plantadas en el sur de México / Aboveground biomass allocation of Pinus greggii provenances planted in southern México

    Scientific Electronic Library Online (English)

    Daniel E., Villegas-Jiménez; Gerardo, Rodríguez-Ortiz; Vicente A., Velasco-Velasco; Judith, Ruiz-Luna; José C., Carrillo-Rodríguez; Susana E., Ramírez-Sánchez.

    2013-12-01

    Full Text Available La asignación de biomasa en los órganos del árbol puede ser influenciada por factores climáticos y edafológicos, competencia lumínica, y por diferencias genéticas de los árboles. El objetivo fue estimar los componentes de biomasa aérea en 13 procedencias mexicanas de Pinus greggii Engelm. plantadas [...] en 1997 en el sur de México. Se utilizaron datos de biomasa obtenidos en 2011 de 106 muestras aleatorias de ramas, 60 árboles medidos en pie y datos generales de la plantación establecida bajo un diseño experimental de bloques al azar. Se encontraron diferencias significativas (P ? 0.05) entre procedencias en acumulación de biomasa en acículas y madera con corteza. La mayor biomasa foliar fue para las procedencias del centro del país, El Piñón y Molango (5.1 t ha-1), mientras que la procedencia norteña, Los Lirios, acumuló la mayor cantidad de biomasa en madera con corteza (19.4 t ha-1). No hubo diferencias en biomasa de ramas cuyo promedio fue de 9.5 t ha-1, ni en la biomasa aérea total acumulada que fue de 25.6 t ha-1, en árboles de 14 años de edad para todas las procedencias. La biomasa se distribuyó 52.0, 33.6 y 14.4 % para madera con corteza, ramas y follaje, respectivamente. Abstract in english Biomass allocation on the tree may be influenced by climate, soil conditions, light competition and genetic differences among trees. Aboveg-round biomass components were estimated in 13 Mexican provenances of Pinus greggii Engelm. planted in 1997 in Southern México. Biomass data were collected in 20 [...] 11 from 106 random samples of branches and 60 standing trees. Data sampling was distributed under a randomized block design. Significant differences (P ? 0.05) among provenances in biomass accumulation of needles and wood + bark were found. The highest leaf biomass accumulation was for provenances from Central México, El Piñón y Molango (5.1 t ha-1). Among the northern provenances, Los Lirios accumulated the highest biomass in wood + bark (19.4 t ha-1). No differences among provenances were found in branch biomass, with an average of 9.5 t ha-1, and neither in total accumulated biomass which was 25.6 t ha-1, for 14 year-old trees. Total biomass was distributed 52.0, 33.6 and 14.4 % for wood + bark, branches and leaves, respectively.

  3. Enfermedad pulmonar obstructiva crónica por exposición al humo de biomasa / Chronic obstructive pulmonary disease by biomass smoke exposure

    Scientific Electronic Library Online (English)

    Matías, Lopez; Nicole, Mongilardi; William, Checkley.

    2014-03-01

    Full Text Available SciELO Public Health | Language: Spanish Abstract in spanish En este artículo se discute la relación existente entre la enfermedad pulmonar obstructiva crónica (EPOC) y el humo de biomasa. Más de la mitad de la población utiliza biomasa como combustible principal, sobre todo en áreas rurales y en países en vías de desarrollo donde su uso llega hasta el 80%. L [...] a inhalación del humo de biomasa crea un estado inflamatorio crónico, que se acompaña de una activación de metaloproteinasas y una reducción de la movilidad mucociliar. Esto podría explicar la gran asociación existente entre la exposición a biomasa y EPOC, revelada por estudios observacionales y epidemiológicos provenientes de países en vías de desarrollo y de países desarrollados. En esta revisión exploramos también las diferencias entre la EPOC causada por tabaco y por biomasa, y encontramos que, a pesar de las diferencias fisiopatológicas, la mayoría de las características clínicas, calidad de vida y mortalidad fueron parecidas. En los últimos diez años se han realizado intervenciones para disminuir la exposición a biomasa mediante el uso de cocinas mejoradas y combustibles limpios, sin embargo, estas estrategias todavía no han sido exitosas debido a su incapacidad para reducir los niveles de contaminación a niveles recomendados por la Organización Mundial de la Salud, y por su falta de uso. Por lo tanto, hay una necesidad urgente de ensayos de campo aleatorios, cuidadosamente realizados, para determinar la verdadera gama de reducciones de contaminación potencialmente alcanzables, la probabilidad de su uso y los beneficios a largo plazo en la reducción de la gran carga mundial de EPOC Abstract in english In this article, the relationship between chronic obstructive pulmonary disease (COPD) and biomass smoke will be discussed. More than half of the world population uses biomass for fuel, especially in rural areas and in developing countries where usage reaches 80%. Biomass smoke inhalation creates an [...] inflammatory chronic state, which is accompanied by metalloproteinases activation and mucociliary mobility reduction. This could explain the existing association between biomass exposure and COPD, revealed by observational and epidemiological studies from developing and developed countries. In this review, the differences between COPD caused by tobacco and biomass were explored. It was found that despite the pathophysiological differences, most of the clinical characteristics, quality of life and mortality were similar. In the last ten years there have been interventions to reduce the biomass smoke exposure by using improved stoves and cleaner fuels. However, these strategies have not yet been successful due to inability to reduce contamination levels to those recommended by the World Health Organization as well as due to the lack of use. Therefore, there is an urgent need for carefully conducted, randomized field trials to determine the actual range of potentially reachable contamination reductions, the probability of use and the long term benefits of reducing the global burden of COPD

  4. Enfermedad pulmonar obstructiva crónica por exposición al humo de biomasa / Chronic obstructive pulmonary disease by biomass smoke exposure

    Scientific Electronic Library Online (English)

    Matías, Lopez; Nicole, Mongilardi; William, Checkley.

    2014-01-01

    Full Text Available SciELO Peru | Language: Spanish Abstract in spanish En este artículo se discute la relación existente entre la enfermedad pulmonar obstructiva crónica (EPOC) y el humo de biomasa. Más de la mitad de la población utiliza biomasa como combustible principal, sobre todo en áreas rurales y en países en vías de desarrollo donde su uso llega hasta el 80%. L [...] a inhalación del humo de biomasa crea un estado inflamatorio crónico, que se acompaña de una activación de metaloproteinasas y una reducción de la movilidad mucociliar. Esto podría explicar la gran asociación existente entre la exposición a biomasa y EPOC, revelada por estudios observacionales y epidemiológicos provenientes de países en vías de desarrollo y de países desarrollados. En esta revisión exploramos también las diferencias entre la EPOC causada por tabaco y por biomasa, y encontramos que, a pesar de las diferencias fisiopatológicas, la mayoría de las características clínicas, calidad de vida y mortalidad fueron parecidas. En los últimos diez años se han realizado intervenciones para disminuir la exposición a biomasa mediante el uso de cocinas mejoradas y combustibles limpios, sin embargo, estas estrategias todavía no han sido exitosas debido a su incapacidad para reducir los niveles de contaminación a niveles recomendados por la Organización Mundial de la Salud, y por su falta de uso. Por lo tanto, hay una necesidad urgente de ensayos de campo aleatorios, cuidadosamente realizados, para determinar la verdadera gama de reducciones de contaminación potencialmente alcanzables, la probabilidad de su uso y los beneficios a largo plazo en la reducción de la gran carga mundial de EPOC Abstract in english In this article, the relationship between chronic obstructive pulmonary disease (COPD) and biomass smoke will be discussed. More than half of the world population uses biomass for fuel, especially in rural areas and in developing countries where usage reaches 80%. Biomass smoke inhalation creates an [...] inflammatory chronic state, which is accompanied by metalloproteinases activation and mucociliary mobility reduction. This could explain the existing association between biomass exposure and COPD, revealed by observational and epidemiological studies from developing and developed countries. In this review, the differences between COPD caused by tobacco and biomass were explored. It was found that despite the pathophysiological differences, most of the clinical characteristics, quality of life and mortality were similar. In the last ten years there have been interventions to reduce the biomass smoke exposure by using improved stoves and cleaner fuels. However, these strategies have not yet been successful due to inability to reduce contamination levels to those recommended by the World Health Organization as well as due to the lack of use. Therefore, there is an urgent need for carefully conducted, randomized field trials to determine the actual range of potentially reachable contamination reductions, the probability of use and the long term benefits of reducing the global burden of COPD

  5. Biomasa fúngica y bacteriana como indicadoras del secuestro de C en suelos de sabanas sustituidos por pinares en Uverito, Venezuela

    Scientific Electronic Library Online (English)

    Magalis, Zabala; Yrma, Gómez.

    2010-09-01

    Full Text Available Cualquier transformación de un ecosistema natural a un sistema agrícola o forestal conduce a una modificación importante no sólo del pool del carbono total, sino también del carbono asociado con la biomasa microbiana. Su cuantificación es importante en la determinación del impacto de las prácticas a [...] grícolas y el cambio de uso de la tierra sobre la calidad del suelo. El objetivo de este estudio fue determinar, a través del método de inhibición selectiva, la biomasa fúngica y bacteriana y la relación (H:B) en suelos de sabana nativa sustituidos por pinares (Pinus caribaea var. hondurensis), para establecer si éstos parámetros son indicadores sensibles de cambios en el contenido de carbono en suelos de Uverito, Venezuela. La relación de aditividad del inhibidor (RAI) y la inhibición total por efecto combinado del inhibidor (ITC) se llevaron a cabo para determinar, si los inhibidores microbianos tuvieron actividad sobre otros organismos para los cuales éstos no estaban destinados. La cuantificación de la biomasa fúngica y bacteriana se llevó a cabo mediante el uso de la cycloheximida como inhibidor fúngico, y la estreptomicina y el cloranfenicol como inhibidores bacterianos. Esta investigación evidencia que este cambio de uso de la tierra ejerció un efecto significativo sobre la biomasa microbiana del suelo, y muestra que en el sistema de pinares existe una dominancia del componente fúngico, en contraste con la sabana nativa, en la cual domina la biomasa bacteriana. La sustitución de la sabana nativa por plantaciones de pino en Uverito, promueve un mayor secuestro del carbono en el suelo. Los valores de la relación de aditividad del inhibidor (RAI) tanto para la sabana nativa como para el sistema de pinares, resultaron ambos >1.0. La inhibición total combinada (ITC) resultó menor en el sistema de pinares; a partir de lo cual, es posible inferir que una elevada proporción de la biomasa microbiana fue afectada por la combinación de los inhibidores. Abstract in english Fungal and bacterial biomass as indicators of soil C sequestration in savannas soils substituted by pine plantations. A transformation of any natural ecosystem to an agricultural or forest system leads to an important soil modification, not only in the total carbon pool, but also in the carbon assoc [...] iated to the microbial biomass. This way, carbon quantification on soil quality is important for the determination of impacts of agricultural practices and land use changes. The aim of this study was to the determine, through the selective inhibition technique, the fungal and bacterial biomass, and fungal-to-bacterial ratio (F:B) in pine plantations (Pinus caribaea var. hondurensis), to establish if these parameters are sensible indicators of changes in the carbon content in Uverito soils (Venezuela). Furthermore, the inhibitor additivity ratio (IAR) and total combined inhibition (TCI) were carried out to determine if the antibiotics caused non-target inhibition. The quantification of fungal and bacterial biomass was carried out by using of cyloheximide as fungal inhibitor, and streptomycin and chloranphenicol as specific bacterial inhibitors. This research evidences that this land use change exerted a significant effect on soil microbial biomass, and shows that in pine plantations there is a dominance of the fungal component, in contrast to the native savanna, in which the bacterial biomass dominates. The substitution of native savanna by pine plantation in Uverito promotes a major soil carbon sequestration. The values of the inhibitor additivity ratio (IAR) as for native savanna as pine system, were both>1.0. The total combined inhibition (TCI) was smaller in the pine systems, from which it is possible to infer that a high proportion of microbial biomass was affected by the combination of the inhibitors. Rev. Biol. Trop. 58 (3): 977-989. Epub 2010 September 01.

  6. Mo-Doped BiVO4 Photoanodes Synthesized by Reactive Sputtering.

    Science.gov (United States)

    Chen, Le; Toma, Francesca M; Cooper, Jason K; Lyon, Alan; Lin, Yongjing; Sharp, Ian D; Ager, Joel W

    2015-03-01

    We report a scalable and reproducible method for reactive co-sputtering of Mo-doped BiVO4 thin films with broad compositional control. Optimal photoanode performance is achieved at a Mo concentration of 3?at.?%. Incorporation of Mo promotes growth of large grains and reduces majority carrier transport limitations, resulting in maximum AM1.5G photocurrent densities of 3.5?mA?cm(-2) at 1.23?V vs. RHE in pH?6.8 buffer solution containing 0.1?M Na2 SO3 as a hole scavenger. Operation as a front-illuminated water oxidation photoanode is achieved by balancing the operational stability, catalytic activity, and parasitic optical absorption of a FeOOH oxygen evolution catalyst. FeOOH/Mo:BiVO4 thin film photoanodes enable water oxidation under the front-side illumination conditions used in integrated tandem water splitting devices. PMID:25705871

  7. Componente lento do VO2 em crianças durante exercício pesado de corrida: análise com base em diferentes modelos matemáticos Componente lento de VO2 en niños durante ejercicio arduo de carrera: análisis con base en diferentes modelos matemáticos Slow component of VO2 in children during running exercise performed at heavy intensity domain: analysis with different mathematical models

    Directory of Open Access Journals (Sweden)

    Fabiana Andrade Machado

    2006-12-01

    Full Text Available O objetivo deste estudo foi verificar e quantificar a magnitude do componente lento do consumo de oxigênio (CL em crianças submetidas a exercícios de corrida em esteira rolante, com cargas constantes de intensidade acima do limiar de lactato (75%D, utilizando para isso dois modelos de análise: a modelo matemático com três termos exponenciais; e b modelo deltaVO2 6-3min. Participaram do estudo oito crianças do sexo masculino (11,92 ± 0,63 anos; 44,06 ± 13,01kg; 146,63 ± 7,25cm; e níveis de maturação sexual 1 e 2, aparentemente saudáveis, não treinadas, que realizaram em diferentes dias: 1 teste incremental na esteira rolante para a determinação do consumo de oxigênio de pico (VO2pico e do limiar de lactato (LL; e 2 dois testes de carga constante em esteira rolante durante seis minutos na intensidade de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL]. Para determinação do CL utilizaram-se: a modelo matemático de três termos (Exp3; e b a diferença no VO2 entre o sexto e o terceiro minuto de exercício (deltaVO2 6-3min. O CL foi expresso em valores absolutos (ml/min e também como a contribuição percentual do CL para o aumento do VO2 no final do exercício (%CL. O CL determinado pelo modelo Exp3 (129,69 ± 75,71ml/min e 8,4 ± 2,92% foi significantemente maior do que o obtido pelo modelo deltaVO2 6-3min (68,69 ± 102,54ml/min e 3,6 ± 7,34%. Portanto, os valores de CL obtidos em crianças durante o exercício de corrida realizado no domínio pesado (75%delta são dependentes do modelo de análise (Exp3 x deltaVO2 6-3min.El objetivo de este estudio ha sido el de verificar y cuantificar la magnitud del componente lento del consumo de oxígeno (CL en niños, sometidos a ejercicios de carrera en cinta rodante, con cargas constantes de intensidad por encima del límite de lactato (75%delta, utilizando para esto dos modelos de análisis: a modelo matemático con tres términos exponenciales; y b modelo deltaVO2 6-3 min. Participaron del estudio 8 niños del sexo masculino (11,92 ± 0,63 años; 44,06 ± 13,01 kg; 146,63 ± 7,25 cm; y niveles de madurez sexual 1 y 2, aparentemente saludables, no entrenados, que realizaron en diferentes días: 1 Test incremental en la cinta rodante para determinar el consumo de oxígeno de pico (VO2pico y del límite de lactato (LL; y 2 Dos tests de carga constante en cinta rodante durante seis minutos a intensidad de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL]. Para determinar el CL usamos: a modelo matemático de tres términos (Exp3; y b la diferencia en el VO2 entre el sexto y el tercer minuto de ejercicio (deltaVO2 6-3 min. El CL fue expresado en valores absolutos (ml/min y también como contribución porcentual de CL para el aumento de VO2 al final del ejercicio (%CL. El CL determinado por el modelo Exp3 (129,69 ± 75,71 ml/min y 8,4 ± 2,92% fue significativamente mayor al que fue obtenido por el modelo deltaVO2 6-3 min (68,69 ± 102,54 ml/min y 3,6 ± 7,34%. Por tanto, los valores de CL obtenidos en niños durante el ejercicio de carrera realizado en dominio pesado (75%delta son dependientes del modelo de análisis (Exp3 x deltaVO2 6-3 min.The purpose of this study was to identify and quantify the magnitude of the slow component of VO2 (SC in children during running exercise, performed at heavy intensity domain (75%delta, using two different mathematical models: a three-exponential model and; b deltaVO2 6-3 min. Eight healthy male children (11.92 ± 0.63 years; 44.06 ± 13.01 kg; 146.63 ± 7.25 cm; and sexual maturity levels 1 and 2, not trained, performed in different days the following tests: 1 incremental running treadmill test to determine the peak oxygen uptake (VO2peak and the lactate threshold (LT; and 2 two transitions from baseline to 75%delta [75%D = LT + 0.75 x (VO2 peak - LT] for six minutes on treadmill. The SC was deter mined by two models: a three-exponential model (Exp3; and b the VO2 difference between the sixth and the third exercise minute (deltaVO2 6-3min. The SC was expressed as the absolute (ml/min and percent contribution

  8. EVALUACIÓN DE LA BIOMASA Y MANEJO DE Lemna gibba (LENTEJA DE AGUA EN LA BAHÍA INTERIOR DEL LAGO TITICACA, PUNO

    Directory of Open Access Journals (Sweden)

    \\u00C1ngel Canales-Guti\\u00E9rrez

    2010-01-01

    Full Text Available Uno de los mayores problemas que enfrenta la ciudad de Puno es la presencia de la lenteja de agua (Lemna gibba en la bahía interior del Lago Titicaca, debido al proceso de eutrofización que sufre a causa del mal tratamiento de las aguas residuales de la ciudad de Puno. Muchas de las estrategias planteadas hasta ahora no han dado resultados positivos en la reducción de la biomasa de Lemna gibba, debido a que estos planes están direccionados a la exterminación de este organismo. En lugar de ello se debe pensar en la forma más sostenible de hacer uso de la lenteja. Es por eso que los objetivos fueron: (a estimar la biomasa (kg/m² de lenteja de agua de la bahía interior del lago Titicaca y, (b plantear una estrategia de manejo de la lenteja de agua de la bahía interior del lago Titicaca. El promedio de la biomasa de la lenteja de agua en la bahía interior fue de 6.94 kg/m², mientras que los promedios de pH y temperatura del agua fueron de 6.3 y 13.8°C, respectivamente. Esto prueba la eficacia de este organismo para crecer en condiciones difíciles (además hay altos niveles de N, P y metales pesados, por lo que su manejo puede ser una alternativa para disminuir el proceso de eutrofización del lago. Las estrategias de manejo de lenteja estuvieron enmarcadas dentro de un plano social, económico y ambiental, lo que permite su sostenibilidad en beneficio de la población de Puno y del ecosistema del lago Titicaca.

  9. Simulink based VoIP Analysis

    CERN Document Server

    Singh, Hardeep; Mian, M

    2010-01-01

    Voice communication over internet not be possible without a reliable data network, this was first available when distributed network topologies were used in conjunction with data packets. Early network used single centre node network in which a single workstation (Server) is responsible for the communication. This posed problems as if there was a fault with the centre node, (workstation) nothing would work. This problem was solved by the distributed system in which reliability increases by spreading the load between many nodes. The idea of packet switching & distributed network were combined, this combination were increased reliability, speed & responsible for voice communication over internet, Voice-over-IP (VoIP)These data packets travel through a packet-switched network such as the Internet and arrive at their destination where they are decompressed using a compatible Codec (audio coder/decoder) and converted back to analogue audio. This paper deals with the Simulink architecture for VoIP network.

  10. BIOMASA, DENSIDAD Y COMPOSICION ZOOPLANCTONICA DE LA BAHIA DE MOCHIMA, VENEZUELA Zooplankton biomass, density and composition in Mochima Bay, Venezuela

    OpenAIRE

    Brightdoom Márquez-Rojas; Baumar Marín; Di?az-ramos, J. R.; Luis Troccoli

    2008-01-01

    La biomasa, densidad y composición del zooplancton de la bahía de Mochima fueron estudiadas durante 1998. Las muestras fueron recolectadas mensualmente en la entrada de la bahía (estación A) y en la parte interna (estación B) entre enero y diciembre de 1998. En cada estación se realizaron calados oblicuos con una malla estándar de 300 micras y 0,25 m de diámetro de boca a 0-5 y 10-15 m y a una velocidad de dos nudos durante 10 min. El índice de surgencia se calculó a partir de los d...

  11. Efeito do tempo de intervalo da amostra ventilatória na variabilidade do consumo máximo de oxigênio (VO2 máx) em jogadores de futebol profissional / Effect of time intervals of ventilatory sampling in the variability of maximum oxygen uptake in professional soccer players

    Scientific Electronic Library Online (English)

    Paulo Roberto Santos, Silva; Angela, Romano; Ana Maria, Visconti; Alberto Alves de Azevedo, Teixeira; Carla Dal Maso Nunes, Roxo; Gilberto da Silva, Machado; Luciana Collet Winther, Rebello; Jorge Mendes de, Sousa.

    1999-04-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O propósito deste estudo foi verificar, em futebolistas profissionais, o impacto de sete intervalos de tempo sobre a variável fisiológica consumo máximo de oxigênio (VO2 máx). Dezoito jogadores de futebol com média de idade de 24 ± 4 anos (18-31), peso de 72,5 ± 5,9kg (62-83) e estatura de 176,5 ± 7 [...] ,0cm (164-188) foram submetidos a teste ergométrico máximo em esteira rolante, utilizando-se protocolo escalonado contínuo. A resposta de freqüência cardíaca (FC) foi registrada por meio de um eletrocardiógrafo computadorizado de 12 derivações simultâneas. A ventilação pulmonar (V E), o consumo de oxigênio (VO2), a produção de dióxido de carbono (VCO2) e a razão de troca respiratória (RER) foram calculadas a partir de valores medidos por um sistema espirométrico computadorizado. Os resultados deste estudo demonstraram que houve variabilidade significante do VO2 máx (p Abstract in english The purpose of this investigation was to verify the impact of seven ventilatory time intervals on the maximum oxygen uptake (VO2 max) in professional soccer players. Eighteen male soccer players aged 24.4 ± 4 (18-31), weight 72.5 ± 5.9 kg (62-83) and height 176.5 ± 7 cm (164-188) were submitted to a [...] maximum exercise test on treadmill, using the continuous protocol. The heart rate response was recorded by means of computerized ECG with 12 leads, simultaneously. The respiratory exchange ratio, carbon dioxide production, oxygen uptake and pulmonary ventilation were calculated by means of the spirometric computerized system. The results of this study demonstrated that there was significant variability (p

  12. Cloudspace: virtual environments in the VO

    Science.gov (United States)

    Graham, M. J.; Williams, R. D.

    2008-08-01

    The grid community is moving towards providing on-demand computing in the form of virtual workspaces - abstracted execution environments that are dynamically made available to authorized clients. In part this is a reaction to market forces represented by such commercial initiatives as Amazon EC2 and in part a solution to hot service deployment. One danger, though, is that a multiplicity of implementations will lead to a lack of interoperability. Such a concern in the VO regarding distributed data storage led to the development of VOSpace, a lightweight abstraction layer that sits on top of existing storage solutions such as SRB. In this paper, we introduce Cloudspace, a resource-oriented extension of VOSpace, that incorporates UWS, the VO pattern for managing asynchronous services, to form a natural habitat for virtual environments in the VO. A notable feature of the Cloudspace concept is that distributed data and computing can be managed seamlessly through a single mechanism thus making the astronomer's life easier as we move into a new era of sophisticated computational astronomy.

  13. The GIRAFFE Archive : Database and VO access

    Science.gov (United States)

    Royer, F.; Jégouzo, I.; Tajahmady, F.; Normand, J.

    2012-09-01

    GIRAFFE is an intermediate and high resolution multi-fibre spectrograph installed at VLT/UT2 (ESO) since 2003. It produces 1D spectra in its multi-object configuration and 3D spectra using its integral field unit configurations. The raw data collected by the instrument (science and calibrations) are part of the ESO archive (http://archive.eso.org). The GIRAFFE Archive, developed in Paris Observatory, provides reduced spectra from the observations made by the instrument once they are publicly available. These spectra are automatically reduced using the ESO GIRAFFE data reduction pipeline. The reduced spectra can be accessed via the web interface of the database (giraffe-archive.obspm.fr'>http://giraffe-archive.obspm.fr), which offers a large range of selection criteria, including individual target positions, magnitudes, signal-to-noise ratios, together with an interactive quick look of the reduced spectra. They also can be accessed in the Virtual Observatory via the SSA web service of VO-Paris Data Centre (http://voparis-srv.obspm.fr/portal/). Two collections are available in the VO: the 1D spectra (summed in the case of integral field observations) and the 3D field observations. These latter products can be explored using the VO Paris Euro3D Client (http://voplus.obspm.fr/ chil/Euro3D/).

  14. VO Compliant Visualization of Theoretical Data

    Science.gov (United States)

    Molinaro, M.; Manzato, P.; Pasian, F.; Becciani, U.; Costa, A.; Massimino, P.; Grillo, A.; Comparato, M.; Cassisi, S.; Pietrinferni, A.; Gheller, C.; Brunino, R.

    2010-12-01

    In the painstaking effort aimed at defining standards for the inclusion of theoretical data in the VO by testing the compliance of as many simulation services as possible, some updates delivered by the Italian Theoretical Virtual Observatory (ITVO) project are presented. They include cosmological simulated data archive s and services (at Trieste and Catania Astronomical Observatories and at the CINECA supercomputing centre in Bologna) and stellar simulations data archive s and services (BaSTI, a Bag of Stellar Tracks and Isochrones, maintained at the Teramo Astronomical Observatory). Following an upgrade in BaSTI database and a new Web service endpoint for VisIVOweb in Trieste some improvements in data visualization are presented: from new plots for BaSTI tracks emphasizing star evolution’s key points to their comparison with observational data, from direct 3D visualization of galaxy clusters to their direct online data manipulation server side using the VO-compliant VisIVOWeb service. Finally we present a new unique Web portal for the ITVO project under VObs.it, the Italian effort in the VO world, that collects all information regarding the various tokens of this theoretical virtual observatory project that are spread all over Italy.

  15. Synergistic effects of VO(x)-Pt probed by the oxidation of propane on VO(x)/Pt(111).

    Science.gov (United States)

    Zheng, Yanping; Zhang, Lihua; Wang, Shaolin; Ding, Ding; Zhang, Hong; Chen, Mingshu; Wan, Huilin

    2013-07-23

    VO(x)/Pt(111), which was grown layer-by-layer and exhibited a well-defined structure, was used as a model catalytic surface to study the intrinsic catalytic activity of Pt, as well as the effect of VO(x) additive, for the oxidation of propane. A special sample system was designed to ensure a reliable analysis of the trace amount of model catalytic reaction products. The results show that the catalytic activities for the oxidation of C3H8 on the Pt(111) surface as adding VO(x) are suppressed apparently at temperatures below 400 K, but enhanced significantly at temperatures above 400 K. Maximum reaction rates are achieved at a VO(x) coverage of about 0.3 ML at the test temperatures of 423 and 473 K. The infrared reflection-absorption spectroscopy (IRAS) results show that the redox property of the VO(x)-Pt is much better than that of the bulklike VO(x). This is confirmed by CO poisoning tests, in that the oxidation of VO(x)/Pt(111) is significantly suppressed by the coadsorbed CO. The kinetic data demonstrate that there are at least two catalytically active sites, metallic Pt and VO(x)-Pt interface, for the activation and oxidation of C3H8. The promotion effects of VO(x) on Pt for the oxidation of C3H8 can be attributed to the synergy between VO(x) and Pt. PMID:23763512

  16. Cambios en el porcentaje de sodio intercambiable (PSI y la relación de absorción de sodio (RAS de un suelo y su influencia en la actividad y biomasa microbiana

    Directory of Open Access Journals (Sweden)

    Torrente Trujillo Armando

    2011-03-01

    Full Text Available

    Con el objetivo de evaluar los cambios en el PSI, la RAS y su influencia en la actividad y  biomasa  microbiana  del suelo,  se aplicaron  diversas  concentraciones  de vinaza  como enmienda procedente de la industria de alcohol carburante, sobre un suelo afectado por sodicidad con severas limitaciones en las condiciones físicas, químicas y biológicas. Se aplicó un diseño en bloques completos al azar que incluye cuatro tratamientos y tres repeticiones, y muestreos de suelo al inicio y final del proceso a tres profundidades (0-20, 20-40 y 40-60 cm, cuyas variables de respuesta a medir fueron  la respiración, C- biomasa microbiana, MO%, pH, CIC, CE, RAS y PSI. La actividad biológica (CO2 y el C-biomasa microbiana mostraron

    incrementos significativos en el rango ideal para el establecimento del cultivo de caña.

  17. Deployment of VoIP Technology: QoS Concerns

    OpenAIRE

    Lazzez, Amor; Slimani, Thabet

    2013-01-01

    Voice over IP (VoIP) is an emerging communication service allowing voice transmission over a private or a public IP network. VoIP allows significant benefits for customers and service providers including cost savings, phone and service portability, mobility, and the integration with other applications. Nevertheless, the deployment of the VoIP technology encounters many challenges such as interoperability issues, security issues, and QoS concerns. Among these disadvantages, Q...

  18. The VO-Neural project: recent developments and some applications

    OpenAIRE

    Brescia, M.; Cavuoti, S.; D Angelo, G.; D Abrusco, R.; Deniskina, N.; Garofalo, M.; Laurino, O.; Longo, G.; Nocella, A.; Skordovski, B.

    2008-01-01

    VO-Neural is the natural evolution of the Astroneural project which was started in 1994 with the aim to implement a suite of neural tools for data mining in astronomical massive data sets. At a difference with its ancestor, which was implemented under Matlab, VO-Neural is written in C++, object oriented, and it is specifically tailored to work in distributed computing architectures. We discuss the current status of implementation of VO-Neural, present an application to the c...

  19. Intrusion detection mechanisms for VoIP applications

    CERN Document Server

    Nassar, M E B; Festor, O; Nassar, Mohamed El Baker; State, Radu; Festor, Olivier

    2006-01-01

    VoIP applications are emerging today as an important component in business and communication industry. In this paper, we address the intrusion detection and prevention in VoIP networks and describe how a conceptual solution based on the Bayes inference approach can be used to reinforce the existent security mechanisms. Our approach is based on network monitoring and analyzing of the VoIP-specific traffic. We give a detailed example on attack detection using the SIP signaling protocol.

  20. Análisis de biomasa del vuelo de un rodal adulto de Pinus radiata / Analysis of aboveground biomass in a mature stand of Pinus radiata

    Scientific Electronic Library Online (English)

    CLAUDIO, MUÑOZ RIVEROS; JORGE, CANCINO C; MIGUEL, ESPINOSA B.

    2005-12-01

    Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Se realizó un estudio de biomasa en árboles de Pinus radiata D. Don de 42 años, obtenidos de un rodal ubicado entre las ciudades de Santa Juana y Nacimiento, VIII Región, Chile. El rodal se diferenció en tres clases de copa: dominante, codominante e intermedio. En cada clase de copa se obtuvieron va [...] lores de biomasa para cada componente (madera, corteza, ramas, ramillas y acículas); la madera resultó ser el componente que más aportó a la biomasa total sobre el suelo (88,9%), seguido de la corteza (8,2%) y ramas (1,5%). Con los valores de biomasa obtenidos, se ajustaron funciones de biomasa por componente, relacionando estos valores con variables del árbol; el dap (diámetro a la altura del pecho) y el dbc (diámetro en la base de la copa viva) fueron las variables que mostraron mayor correlación con los valores de biomasa por componente y menores errores de estimación. Abstract in english A study of biomass in Pinus radiata D. Don with 42 years old was made, the trees were obtained of a stand placed between the cities of Santa Juana and Nacimiento, VIII Region, Chile. Three classes of top were differentiated in the stand: dominant, codominant and intermediate. The value of the mass f [...] or each component (wood, bark, branches, branchlets and needle) was obtained from each class of top; the wood resulted as the most important component in the total biomass of the tree (88.9%), then the bark (8.2%) and branches (1.5%). Obtained the values of biomass, the function of biomass for each component was obtained, related this values with the variables of the tree; the variables that showed greater correlation with the values of biomass by component and minors estimation errors are dbh (breast height diameter) and dbc (base of live crown diameter).

  1. Photoemission study of TiO2/VO2 interfaces

    OpenAIRE

    Maekawa, K.; Takizawa, M.; Wadati, H.; Yoshida, T.; Fujimori, A.; Kumigashira, H.; Oshima, M.; Muraoka, Y.; Nagao, Y.; Hiroi, Z.

    2006-01-01

    We have measured photoemission spectra of two kinds of TiO$_2$-capped VO$_2$ thin films, namely, that with rutile-type TiO$_2$ (r-TiO$_2$/VO$_2$) and that with amorphous TiO$_2$ (a-TiO$_2$/VO$_2$) capping layers. Below the Metal-insulator transition temperature of the VO$_2$ thin films, $\\sim 300$ K, metallic states were not observed for the interfaces with TiO$_2$, in contrast with the interfaces between the band insulator SrTiO$_3$ and the Mott insulator LaTiO$_3$ in spite...

  2. Efecto de la depuración en la biomasa del caracol Pomacea patula [Baker, 1922] usando el índice de condición

    Directory of Open Access Journals (Sweden)

    M. Garc\\u00EDa-Ulloa

    2006-01-01

    Full Text Available La depuración de organismos acuáticos en cultivo es una práctica común. El tiempo de exposición de los animales al agua tratada es uno de los factores más importantes para su eficiencia, pudiendo afectar su biomasa. Se evaluó el efecto de la depuración en adultos de Pomacea patula mediante la aplicación del índice de condición (IC, bajo condiciones de laboratorio. Caracoles adultos obtenidos en cultivo se mantuvieron en peceras (Grupo 1 expuestos a un flujo de agua constante, tratada con radiación ultravioleta y limpieza diaria y en condiciones normales de mantenimiento (Grupo 2, con 5 réplicas por grupo. Se obtuvo el peso húmedo y longitud total individualmente, al inicio y después de una depuración de 10 días. El valor promedio del coeficiente de correlación (animales iniciales y de los Grupos 1 y 2 fue mayor a 0.90. El IC entre el valor inicial (771.81 ± 40.41 y los Grupos 1 y 2 (763.527 ± 25.24 y 765.465 ± 38.59, respectivamente, no mostró diferencias significativas (P > 0.05 al final del experimento. Los resultados sugieren que el proceso de depuración usado no afectó la biomasa de adultos de P. patula. El IC se mostró como una herramienta práctica de evaluación sin considerar la diferencia inicial de tallas de caracoles adultos

  3. Producción de Biomasa en el Mejillon verde de localidad de la Península de Araya, Venezuela.

    Scientific Electronic Library Online (English)

    Carmen J, Malavé; Antulio S, Prieto Arcas.

    2005-11-01

    Full Text Available SciELO Venezuela | Language: Spanish Abstract in portuguese O mexilhão verde Perna viridis, originário do Indo-Pacifico foi identificado e relatado no Golfo de Paria em 1993, causando por sua abundancia grande impacto nas comunidades costeiras. A produção específica dos componentes da biomassa individual de P. viridis foi determinada em uma população natural [...] em Guayacán, estado Sucre, Venezuela. Amostras mensais se realizaram entre agosto '02 e agosto '03, e as biomassas (peso seco) de gônada, músculo adutor, resto de tecidos somáticos e matriz orgânica da concha foram avaliadas utilizando equações mensais longitude-peso seco e um modelo de crescimento local. Nas amostras se determinaram temperatura da água, salinidade, O2 dissolvido e disponibilidade de alimento (clorofila a). O maior peso seco gônada (pg) se observou em agosto de ambos anos, com mínimos em julho para as idades maiores, com três prováveis períodos de desove. O resto de tecido somático (prt) apresentou máximo em setembro e mínimo em junho, e o músculo (pm) máximo em agosto '03 e mínimo em maio. A produção de tecido somático (Prt), músculo adutor (Pm) e matéria orgânica da concha (Pc) foram máximas aos 12 meses, diminuindo posteriormente. A produção de gônadas (Pg) nos períodos de desove aumentou de 0,10g aos 6 meses até 1,15g a 2,5 anos. A produção total (P) aumentou com a idade, mas a relação P/B diminuiu. O esforço reprodutivo (Pg/P) aumentou de 0,13g até 0,71g aos 2,5 anos, revelando uma estratégia populacional de alta produtividade de gônadas que garante o alto potencial biótico da espécie. Abstract in spanish El mejillón verde Perna viridis, originario del Indo-Pacifico fue reportado en el Golfo de Paria en 1993, causando por su abundancia gran impacto en las comunidades costeras. La producción específica de los componentes de la biomasa individual de P. viridis fue determinada en una población natural e [...] n Guayacán, estado Sucre, Venezuela. Muestreos mensuales se realizaron entre agosto ‘02 y agosto ’03, y las biomasas (peso seco) de gónada, músculo aductor, resto de tejidos somáticos y matriz orgánica de la concha fueron evaluadas utilizando ecuaciones mensuales longitud-peso seco y un modelo de crecimiento local. En los muestreos se determinaron temperatura del agua, salinidad, O2 disuelto y disponibilidad de alimento (clorofila a). El mayor peso seco gonadal (pg) se observó en agosto de ambos años, con mínimos en julio para las edades mayores, con tres probables periodos de desove. El resto de tejido somático (prt) presentó máximo en setiembre y mínimo en junio, y el músculo (pm) máximo en agosto ‘03 y mínimo en mayo. La producción de tejido somático (Prt), músculo aductor (Pm) y materia orgánica de la concha (Pc) fueron máximas a los 12 meses, disminuyendo posteriormente. La producción de gónadas (Pg) en los periodos de desove aumentó de 0,10g a los 6 meses hasta 1,15g a 2,5 años. La producción total (P) aumentó con la edad, pero la relación P/B disminuyó. El esfuerzo reproductivo (Pg/P) aumentó de 0,13g hasta 0,71g a los 2,5 años, revelando una estrategia poblacional de alta productividad de gónadas que garantiza el alto potencial biótico de la especie. Abstract in english The green mussel Perna viridis, native of the Indo-Pacific, was reported in the Gulf of Paria in 1993, causing large impact in the local coastal communities due to their abundance. Specific production of individual biomass components in a natural population of P. viridis was determined in Guayacan, [...] Sucre state, Venezuela. The Monthly samplings were carried out between August ’02 and August ‘03 and the biomass (dry weight) of gonad, adductor muscle, remaining somatic tissues and shell organic material were evaluated using monthly length-dry weight equations and a model of local population growth. In the samplings, water temperature, salinity, dissolved O2 and food availability (chlorophyll a) were determined. The largest dry weight gonadal tissue

  4. Componente lento do VO2 em crianças durante exercício pesado de corrida: análise com base em diferentes modelos matemáticos / Slow component of VO2 in children during running exercise performed at heavy intensity domain: analysis with different mathematical models / Componente lento de VO2 en niños durante ejercicio arduo de carrera: análisis con base en diferentes modelos matemáticos

    Scientific Electronic Library Online (English)

    Fabiana Andrade, Machado; Luiz Guilherme Antonacci, Guglielmo; Camila Coelho, Greco; Benedito Sérgio, Denadai.

    2006-12-01

    Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in portuguese O objetivo deste estudo foi verificar e quantificar a magnitude do componente lento do consumo de oxigênio (CL) em crianças submetidas a exercícios de corrida em esteira rolante, com cargas constantes de intensidade acima do limiar de lactato (75%D), utilizando para isso dois modelos de análise: a) [...] modelo matemático com três termos exponenciais; e b) modelo deltaVO2 6-3min. Participaram do estudo oito crianças do sexo masculino (11,92 ± 0,63 anos; 44,06 ± 13,01kg; 146,63 ± 7,25cm; e níveis de maturação sexual 1 e 2), aparentemente saudáveis, não treinadas, que realizaram em diferentes dias: 1) teste incremental na esteira rolante para a determinação do consumo de oxigênio de pico (VO2pico) e do limiar de lactato (LL); e 2) dois testes de carga constante em esteira rolante durante seis minutos na intensidade de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL)]. Para determinação do CL utilizaram-se: a) modelo matemático de três termos (Exp3); e b) a diferença no VO2 entre o sexto e o terceiro minuto de exercício (deltaVO2 6-3min). O CL foi expresso em valores absolutos (ml/min) e também como a contribuição percentual do CL para o aumento do VO2 no final do exercício (%CL). O CL determinado pelo modelo Exp3 (129,69 ± 75,71ml/min e 8,4 ± 2,92%) foi significantemente maior do que o obtido pelo modelo deltaVO2 6-3min (68,69 ± 102,54ml/min e 3,6 ± 7,34%). Portanto, os valores de CL obtidos em crianças durante o exercício de corrida realizado no domínio pesado (75%delta) são dependentes do modelo de análise (Exp3 x deltaVO2 6-3min). Abstract in spanish El objetivo de este estudio ha sido el de verificar y cuantificar la magnitud del componente lento del consumo de oxígeno (CL) en niños, sometidos a ejercicios de carrera en cinta rodante, con cargas constantes de intensidad por encima del límite de lactato (75%delta), utilizando para esto dos model [...] os de análisis: a) modelo matemático con tres términos exponenciales; y b) modelo deltaVO2 6-3 min. Participaron del estudio 8 niños del sexo masculino (11,92 ± 0,63 años; 44,06 ± 13,01 kg; 146,63 ± 7,25 cm; y niveles de madurez sexual 1 y 2), aparentemente saludables, no entrenados, que realizaron en diferentes días: 1) Test incremental en la cinta rodante para determinar el consumo de oxígeno de pico (VO2pico) y del límite de lactato (LL); y 2) Dos tests de carga constante en cinta rodante durante seis minutos a intensidad de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL)]. Para determinar el CL usamos: a) modelo matemático de tres términos (Exp3); y b) la diferencia en el VO2 entre el sexto y el tercer minuto de ejercicio (deltaVO2 6-3 min). El CL fue expresado en valores absolutos (ml/min) y también como contribución porcentual de CL para el aumento de VO2 al final del ejercicio (%CL). El CL determinado por el modelo Exp3 (129,69 ± 75,71 ml/min y 8,4 ± 2,92%) fue significativamente mayor al que fue obtenido por el modelo deltaVO2 6-3 min (68,69 ± 102,54 ml/min y 3,6 ± 7,34%). Por tanto, los valores de CL obtenidos en niños durante el ejercicio de carrera realizado en dominio pesado (75%delta) son dependientes del modelo de análisis (Exp3 x deltaVO2 6-3 min). Abstract in english The purpose of this study was to identify and quantify the magnitude of the slow component of VO2 (SC) in children during running exercise, performed at heavy intensity domain (75%delta), using two different mathematical models: a) three-exponential model and; b) deltaVO2 6-3 min. Eight healthy male [...] children (11.92 ± 0.63 years; 44.06 ± 13.01 kg; 146.63 ± 7.25 cm; and sexual maturity levels 1 and 2), not trained, performed in different days the following tests: 1) incremental running treadmill test to determine the peak oxygen uptake (VO2peak) and the lactate threshold (LT); and 2) two transitions from baseline to 75%delta [75%D = LT + 0.75 x (VO2 peak - LT)] for six minutes on treadmill. The SC was deter mined by two models: a) three-exp

  5. Preparation and crystal structure of a new bismuth vanadate, Bi3.33(VO4)2O2

    International Nuclear Information System (INIS)

    Graphical abstract: Crystal structure of Bi3.33(VO4)2O2. Solid lines indicate the unit cell. Highlights: ? We can prepare a new bismuth vanadate, Bi3.33(VO4)2O2 by hydrothermal reaction using a hydrated sodium bismuthate. ? We clarify that the crystal structure is composed by four bismuth atoms with the coordination number of 6 or 8 and two VO4 tetrahedra. ? This compound exhibited photocatalytic behavior for decomposition of phenol under visible light irradiation. -- Abstract: Single crystals of a new bismuth vanadate, Bi3.33(VO4)2O2 was prepared by hydrothermal reaction using a hydrated sodium bismuthate, NaBiO3.nH2O as one of the starting compounds. The crystal structure was determined by using single crystal X-ray diffraction data. This compound crystallizes in the triclinic space group P1-bar (no. 2) with a = 7.114(1), b = 7.844(2), c = 9.372(2) A, ? = 106.090(7), ? = 94.468(7) and ? = 112.506(8)o, Z = 2 and the final R factors are R1 = 0.052 and wR2 = 0.14 for 2085 unique reflections. The crystal structure is composed by four bismuth atoms with the coordination number of 6 or 8 and two VO4 tetrahedra, and one of four bismuth atoms is statistically distributed in the splitting sites with the distance of 0.83 A. This compound exhibited photocatalytic behavior for decomposition of phenol under visible light irradiation and its activity was less than that of monoclinic BiVO4.

  6. Spectroscopic Analysis in the Virtual Observatory Environment with SPLAT-VO

    OpenAIRE

    Skoda, Petr; Draper, Peter W.; Neves, Margarida Castro; Andresic, David; Jenness, Tim

    2014-01-01

    SPLAT-VO is a powerful graphical tool for displaying, comparing, modifying and analyzing astronomical spectra, as well as searching and retrieving spectra from services around the world using Virtual Observatory (VO) protocols and services. The development of SPLAT-VO started in 1999, as part of the Starlink StarJava initiative, sometime before that of the VO, so initial support for the VO was necessarily added once VO standards and services became available. Further develop...

  7. Electrochemical activation of graphite felt electrode for VO2+/VO2+ redox couple application

    International Nuclear Information System (INIS)

    In this work, the electrochemical activation of graphite felt electrode for vanadium redox flow battery (VRB) was studied. Graphite felt (GF) electrode was oxidized at a range of electrochemical oxidation degrees in H2SO4 solution. The electrochemical performance of the treaded GF was discussed, and the law of the surface properties of GF which changed along with the electrochemical oxidation degree was proposed. The structure, composition, surface tension and electrochemical properties of the oxidized GF (OGF) were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The GF oxidized at 560–840 mAh g?1 exhibited the best activity toward VO2+/VO2+ redox reaction, according with the highest C-OH and COOH content (ca. 34%) on its surface. The mechanisms of VO2+/VO2+ redox reaction on OGF were also discussed. VRB single cell with pristine GF and OGF as the electrode were test at various charge–discharge current densities, respectively. The columbic efficiency (CE), voltage efficiency (VE) and energy efficiency (EE) of the cell using OGF electrode are much higher than the cell using pristine GF, suggested that the electro-oxidation method is a promising technology for the activation of GF electrode

  8. Evolution of the spectral weight in the Mott-Hubbard series SrVO3-CaVO3-LaVO3-YVO3

    International Nuclear Information System (INIS)

    The Mott-Hubbard series SrVO3-CaVO3-LaVO3-YVO3 present a distinct metal-insulator transition. The microscopic origin of this transition can be related to the correlation effects in the electronic structure. The valence band photoemission results show very interesting trends across these Mott-Hubbard series. These results suggest that the O 2p states play an important role in the Mott-Hubbard transition. Some of the changes in the spectra are unexpected and cannot be explained by the current Mott-Hubbard theories (author)

  9. Reproducibility of maximum aerobic power (VO2max) among soccer players using a modified heck protocol / Reprodutibilidade da potência aeróbia máxima (VO2max) em jogadores de futebol utilizando o protocolo de heck modificado

    Scientific Electronic Library Online (English)

    Paulo Roberto, Santos-Silva; Alfredo José, Fonseca; Anita Weigand de, Castro; Júlia Maria D' Andréa, Greve; Arnaldo José, Hernandez.

    Full Text Available OBJETIVO: Determinar o grau de reprodutibilidade do consumo máximo de oxigênio (VO2max) em jogadores de futebol utilizando o protocolo de Heck modificado. MÉTODOS: Foram avaliados por duas vezes, com intervalo de 15 dias entre os testes, 11 futebolistas masculinos. Todos eram de alto nível, treinava [...] m em média 10 horas por semana subdivididos em treinamentos físicos, técnicos, táticos e jogos competitivos, totalizando cinco vezes por semana e na fase em que foram avaliados se encontravam em pleno período competitivo realizando um jogo por semana. Os futebolistas foram avaliados em esteira ergométrica (1,2 km.h-1) a cada dois minutos e inclinação fixa durante o teste em 3%. O VO2max foi medido diretamente utilizando analisador metabólico de análise de gases expirados respiração-a-respiração. RESULTADOS: A velocidade máxima de corrida e o VO2max atingido nos dois testes foram respectivamente: (15,6 ± 1,1 vs. 15,7 ± 1,2 km.h-1; [p = 0,78]) e (54,5 ± 3,9 vs. 55,2 ± 4,4 ml.kg-1.min-1; [P = 0,88]). Houve correlação significante e alta do VO2max entre os dois testes após 15 dias de intervalo [r = 0,97; P Abstract in english OBJECTIVE: To determine the degree of reproducibility of maximum oxygen consumption (VO2max) among soccer players, using a modified Heck protocol. METHODS: 2 evaluations with an interval of 15 days between them were performed on 11 male soccer players. All the players were at a high performance leve [...] l; they were training for an average of 10 hours per week, totaling 5 times a week. When they were evaluated, they were in the middle of the competitive season, playing 1 match per week. The soccer players were evaluated on an ergometric treadmill with velocity increments of 1.2 km.h-1 every 2 minutes and a fixed inclination of 3% during the test. VO2max was measured directly using a breath-by-breath metabolic gas analyzer. RESULTS: The maximum running speed and VO2max attained in the 2 tests were, respectively: (15.6 ± 1.1 vs. 15.7 ± 1.2 km.h-1; [P = .78]) and (54.5 ± 3.9 vs. 55.2 ± 4.4 ml.kg-1.min-1; [P = .88]). There was high and significant correlation of VO2max between the 2 tests with a 15-day interval between them [r = 0.97; P

  10. VoIP makes voice heard--functionality is up.

    Science.gov (United States)

    Wade, Phil; Wakelam, Mathew

    2008-05-01

    Phil Wade, sales and marketing director, and Mathew Wakelam, VoIP product manager, at alarm and communication specialist Static Systems Group, discuss wireless VoLP's potential in healthcare establishments and examine how, in particular, the technology can be successfully integrated with nurse call systems. PMID:18552104

  11. VO2 responses to running speeds above intermittent critical speed.

    Science.gov (United States)

    de Aguiar, R A; Turnes, T; de Oliveira Cruz, R S; Caputo, F

    2012-11-01

    The aim of this study was to examine whether intermittent critical speed (ICS) is the threshold velocity above which intermittent exercise leads to the attainment of VO(2max). After an incremental test, 7 active male subjects (49.7 ± 3.74 mL.min?(-?1).kg?(-?1)) performed 3 intermittent exercises until exhaustion at 100%, 110%, 120% of the velocity associated with VO(2max) to determine ICS. On 4 occasions, the subjects performed intermittent exercise tests until exhaustion at the velocity corresponding to 105% (IE(105)) and 110% (IE(110)) of ICS, and at a speed that was initially set at 125%ICS but which then decreased to 105%ICS (IE(125-105)) in one instance and to 110%ICS (IE(125-110)) in another. The intermittent exercises consisted of repeated 30-s runs alternated with 15-s passive rest intervals. At IE(125)-105, peak VO(2) was not different from VO(2max) but decreased significantly after the change of speed to 105%ICS. During IE(110), peak VO(2) value reached VO(2max) and also during the higher speed at IE(125-110), but did not change when the speed was lowered. These results demonstrated that during intermittent exercise just above ICS (105%) VO(2max) was not elicited, suggesting that ICS might not be the threshold speed above which VO(2max) can be reached. PMID:22706949

  12. Photoemission study of TiO2/VO2 interfaces

    CERN Document Server

    Maekawa, K; Wadati, H; Yoshida, T; Fujimori, A; Kumigashira, H; Oshima, M; Muraoka, Y; Nagao, Y; Hiroi, Z

    2006-01-01

    We have measured photoemission spectra of two kinds of TiO$_2$-capped VO$_2$ thin films, namely, that with rutile-type TiO$_2$ (r-TiO$_2$/VO$_2$) and that with amorphous TiO$_2$ (a-TiO$_2$/VO$_2$) capping layers. Below the Metal-insulator transition temperature of the VO$_2$ thin films, $\\sim 300$ K, metallic states were not observed for the interfaces with TiO$_2$, in contrast with the interfaces between the band insulator SrTiO$_3$ and the Mott insulator LaTiO$_3$ in spite of the fact that both TiO$_2$ and SrTiO$_3$ are band insulators with $d^0$ electronic configurations and both VO$_2$ and LaTiO$_3$ are Mott insulators with $d^1$ electronic configurations. We discuss possible origins of this difference and suggest the importance of the polarity discontinuity of the interfaces. Stronger incoherent part was observed in r-TiO$_2$/VO$_2$ than in a-TiO$_2$/VO$_2$, suggesting Ti-V atomic diffusion due to the higher deposition temperature for r-TiO$_2$/VO$_2$.

  13. Validade preditiva da medida e estimativas do VO2máx no desempenho de Mountain Bikers / Predictive validity of VO2máx measurement and estimates in Mountain Bikers' performance / Validez predictiva de la medida y estimativas del VO2máx en el desempeño de Mountain Bikers

    Scientific Electronic Library Online (English)

    Fernanda, Mainardi; Allan, Inoue; Fernando Augusto de Saboia, Pompeu; Tony Meireles, Santos.

    2015-02-01

    Full Text Available INTRODUÇÃO: considerando o racional para a utilização das equações preditivas na estimativa do VO2máx em atletas, nenhum estudo estabeleceu sua validade para o desempenho no mountain bike cross-country (XCO). OBJETIVO: comparar diferentes estratégias de determinação do VO2máx, de forma direta ou in [...] direta, para a predição do desempenho em uma prova real e outra simulada. MÉTODOS: 20 atletas de XCO do sexo masculino (31,6 ± 6,8 anos; 68,1 ± 6,5 kg; 175,5 ± 5,7cm; 64,9 ± 4,4 mL. kg-1.min-1), foram submetidos a três sessões experimentais. A primeira visita consistiu na estratificação de risco, avaliação antropométrica e teste progressivo máximo. Na segunda, foi realizada a prova simulada e, na terceira, foi realizada a competição de XCO. RESULTADOS: a correlação entre a prova simulada e as equações preditivas do VO2máx de forma absoluta alcançaram relação quase perfeita (r ? 0,9). As correlações entre a competição real e as estimativas de VO2máx relativizadas à massa corporal alcançaram resultados classificados como muito altos (r = 0,7-0,89). As associações entre a medida direta do VO2máx e a simulação apresentaram uma classificação baixa para valores relativos à massa corporal (r = 0,10, IC95% -0,35 a 0,51). Para o desempenho real, a classificação foi moderada (r = 0,48, IC95% 0,009 a 0,78). CONCLUSÃO: o presente estudo foi o primeiro a demonstrar a validade preditiva das estimativas do VO2máx para o desempenho simulado e real de MTB. Em complemento, confirmou a baixa validade preditiva da medida direta do VO2máx para o mesmo propósito. Abstract in spanish INTRODUCCIÓN: considerando el racional para el uso de las ecuaciones predictivas en la estimativa del VO2máx en atletas de ciclismo, ningún estudio estableció su validez predictiva para el desempeño en el mountain bike cross-country (XCO). OBJETIVO: comparar diferentes estrategias de determinación [...] del VO2máx, de forma directa o indirecta, para la predicción del desempeño en una prueba real y otra simulada. MÉTODOS: veinte atletas de XCO del sexo masculino (31,6 ± 6,8 años; 68,1 ± 6,5 kg; 175,5 ± 5,7cm; 64,9 ± 4,4 mL. kg-1.min-1), fueron sometidos a tres sesiones experimentales. La primera visita consistió en la estratificación de riesgo, evaluación antropométrica y test progresivo máximo. En la segunda, fue realizada la prueba simulada y en la tercera fue realizada la competición de XCO. RESULTADOS: la correlación entre la prueba simulada y las ecuaciones predictivas del VO2máx de forma absoluta alcanzaron relación casi perfecta (r ? 0,9). Las correlaciones entre la competición real y las estimativas de VO2máx relativizada a la masa corporal alcanzaron resultados clasificados como muy grande (r = 0,7-0,89). Las asociaciones entre la medida directa del VO2máx y la simulación presentaron clasificación pequeña para valores relativos a masa corporal (r = 0,10, IC95% -0,35 a 0,51). Para el desempeño real, la clasificación fue moderada (r = 0,48, IC95% 0,009 a 0,78). CONCLUSIÓN: el presente estudio fue el primero en demostrar la validez predictiva de las estimativas del VO2máx para el desempeño simulado y real de MTB. En complemento, confirmó la baja validez predictiva de la medida directa del VO2máx para el mismo propósito. Abstract in english INTRODUCTION: considering the rationale for the use of predictive equations to estimate VO2max in athletes, no study has established its validity for performance in mountain bike cross-country (XCO). OBJECTIVE: the aim was to compare different strategies for determining VO2max, directly or indirect [...] ly, for predicting performance in a simulated and in a real competition. METHODS: 20 XCO male athletes (31.6 ± 6.8 anos; 68.1 ± 6.5 kg; 175.5 ± 5.7cm; VO2max 64.9 ± 4.4 mL. kg-1.min-1), were submitted to three experimental sessions. In the first visit, there were risk stratification, anthropometric evaluation and maximum progressive test. In the second, a simulated race was performed and, in the third s

  14. PRODUCCIÓN DE BIOMASA Y EXOPOLISACÁRIDOS DE Grifóla frondosa BAJO CULTIVO SUMERGIDO UTILIZANDO FUENTES DE CARBONO NO CONVENCIONALES

    Directory of Open Access Journals (Sweden)

    Paula Zapata

    2007-06-01

    Full Text Available Grifóla frondosa es un hongo Basidiomycete comestible y medicinal que produce polisacáridos tipo glucanos (?-1,6 y ?-1,3 con actividad antitumoral e inmunomoduladora. Para el presente trabajo, el objetivo fue evaluar la incidencia de diferentes fuentes de carbono (FC en la producción de biomasa y exopolisacári-dos (EPS, bajo condiciones de cultivo sumergido, utilizando un diseño estadístico factorial con dos factores: fuente de carbono (FC(1-7 y medio (MB y MS. La máxima producción de biomasa micelial (21,10 ± 0,82 g/l y la máxima producción de EPS (6,53 ± 0,14 g/l se logró utilizando el medio MB suplementado con FC4. Además de lo anterior, se logró desarrollar un medio de cultivo que cumple con el objetivo de disminuir costos, de Col $18.455 a $656 por litro de medio, produciendo (14,14 ± 0,82 g/l de biomasa y (5,16 ± 0,14 g/l de EPS, utilizando el medio MS suplementando con FC4. Estos resultados abren nuevas alternativas y posibilidades en nuestro país para el desarrollo de productos a partir de esta especie con costos que estén al alcance de la población.Grifóla frondosa is a Basidiomycete fungus edible and medicinal, it produces polysaccharides such a glucans (?-1,6 and ?-1,3 with anti-tumor and inmuno-stimulating activity. For this work, the aim was evaluate the incidence of different carbon sources (FC in biomass and exo-polymer (EPS production, under submerged culture conditions, by using a factorial statistical design with two factors: carbon source (FC(1-7 and medium (MB and MS. The maximal yield of mycelial biomass (21,10 ± 0,82 g/l and the maximal yield in EPS (6,53 ± 0,14 g/l was achieved by using the MB medium supplemented with FC4. Besides, it was possible to develop a medium that fulfills the objective of reducing costs from $18.455 to $656 Colombian pesos for each liter of medium used, which produces (14,14 ± 0,82 g/l of biomass and (5,16 ± 0,14 g/l of EPS, using the MS medium supplemented with FC4. This result opens new alternatives and possibilities in our country for developing products of this species with cost that can be reached by population.

  15. ¿Afectan los aclareos la acumulación de biomasa aérea en una plantación de Pinus patula? / Does thinning affect aboveground biomass acummulation in a Pinus patula plantation?

    Scientific Electronic Library Online (English)

    Gerardo, Rodríguez-Ortíz; Arnulfo, Aldrete; Víctor A., González-Hernández; Héctor M., De Los Santos-Posadas; Armando, Gómez-Guerrero; Aurelio M., Fierros-González.

    2011-09-01

    Full Text Available El aclareo puede modificar la distribución y cantidad de biomasa aérea en función del tiempo de respuesta y de las condiciones de crecimiento. En este estudio se analizó el efecto de aclareos en la distribución y contenido de biomasa aérea acumulada de Pinus patula mediante muestreos destructivos de [...] 30 árboles en 2009, después de estar sometidos a diferentes intensidades de aclareo desde el 2004, más un testigo intacto. La eliminación entre 40 y 69 % de la densidad inicial de plantación afectó significativamente (p ? 0.05) la cantidad y distribución de biomasa foliar y la cantidad de madera con corteza en el fuste a nivel de árbol individual (pero no por ha) en algunos componentes del árbol. Las intensidades altas de aclareo (65.3 y 68.7 %>) y las respectivas densidades residuales bajas generaron la mayor acumulación de biomasa foliar (5.4 kg árbol-1 y 8.0 t ha-1), que superaron (p?0.05) al testigo sin aclareo (1.5 kg árbol-1). En la biomasa de madera con corteza del fuste los árboles con aclareo también superaron (p?0.05) al testigo (98 fs. 35.3 kg árbol-1). Sin embargo, la acumulación de biomasa por unidad de superficie fue similar entre ambas condiciones, debido a la excesiva densidad residual del testigo; lo mismo ocurrió en la biomasa total de ramas y en la distribución en el fuste. Abstract in english Thinning may modify distribution and amount of aboveground biomass according to time of response and growth conditions. In this study, the effect of thinning on distribution and accumulated aboveground biomass content of Pinus patula was analyzed in 2009 through destructive samplings of 30 trees, af [...] ter having been subjected to different thinning intensities since 2004, plus an intact control. Elimination between 40 and 69 % of initial plantation density significantly affected (p?0.05) quantity and distribution of leaf biomass and the amount of timber with bark on the stem at individual tree level in some tree components (but not by ha). The high thinning intensity (65.3 and 68.7 %) and respective low residual density generated the largest accumulation of foliar biomass (5.4 kg tree-1 and 8.0 t ha-1), surpassing (p?0.05) the control without thinning (1.5 kg tree-1). In timber biomass with stem bark, trees with thinning also surpassed (p?0.05) the control (98 fs. 35.3 kg tree-1). However, biomass accumulation per unit was similar between both conditions, due to excessive residual density of the control; the same occurred in total branch biomass and in distribution on the stem.

  16. BIOMASA, DENSIDAD Y COMPOSICION ZOOPLANCTONICA DE LA BAHIA DE MOCHIMA, VENEZUELA / Zooplankton biomass, density and composition in Mochima Bay, Venezuela

    Scientific Electronic Library Online (English)

    Brightdoom, Márquez-Rojas; Baumar, Marín; J.R, Díaz-Ramos; Luis, Troccoli.

    2008-06-01

    Full Text Available La biomasa, densidad y composición del zooplancton de la bahía de Mochima fueron estudiadas durante 1998. Las muestras fueron recolectadas mensualmente en la entrada de la bahía (estación A) y en la parte interna (estación B) entre enero y diciembre de 1998. En cada estación se realizaron calados ob [...] licuos con una malla estándar de 300 micras y 0,25 m de diámetro de boca a 0-5 y 10-15 m y a una velocidad de dos nudos durante 10 min. El índice de surgencia se calculó a partir de los datos de vientos. Se midió salinidad, temperatura del agua, concentración de oxígeno disuelto, concentración de clorofila a, biomasa y densidad del zooplancton; además se identificaron los organismos, en lo posible hasta especie. Los perfiles de temperatura mostraron un mayor tiempo de permanencia de aguas cálidas superficiales en la estación más interna. Los valores más altos de densidad zooplanctónica (4066 ind/m³) se registraron en el período febrero - mayo y luego los valores fueron relativamente bajos ( Abstract in english Zooplankton biomass, density and composition were studied in Mochima Bay during 1998. Samples were collected at monthly intervals at stations located at the mouth and the interior of the bay from January to December 1998. At each station, samples were collected in the intervals 0-5 and 10-15 m with [...] a Standard net of 300 µm and 0,25 m Ø at a speed of two knots during ten minutes. Wind data was used to calculate the upwelling index. Salinity, water temperature, concentration of dissolved oxygen and chlorophyll a (chl a), and zooplankton biomass and density were measured at the two stations. Also, the organisms were identified to group level. Temperature profiles showed a greater residence time for warm waters in the internal part of the bay than in the external one. Higher zooplankton density values (4066 ind/m³) were found during the period February - May. Values were relatively low (

  17. The Effect of Habitual Smoking on VO2max

    Science.gov (United States)

    Wier, Larry T.; Suminski, Richard R.; Poston, Walker S.; Randles, Anthony M.; Arenare, Brian; Jackson, Andrew S.

    2008-01-01

    VO2max is associated with many factors, including age, gender, physical activity, and body composition. It is popularly believed that habitual smoking lowers aerobic fitness. PURPOSE: to determine the effect of habitual smoking on VO2max after controlling for age, gender, activity and BMI. METHODS: 2374 men and 375 women employed at the NASA/Johnson Space Center were measured for VO2max by indirect calorimetry (RER>=1.1), activity by the 11 point (0-10) NASA Physical Activity Status Scale (PASS), BMI and smoking pack-yrs (packs day*y of smoking). Age was recorded in years and gender was coded as M=1, W=0. Pack.y was made a categorical variable consisting of four levels as follows: Never Smoked (0), Light (1-10), Regular (11-20), Heavy (>20). Group differences were verified by ANOVA. A General Linear Models (GLM) was used to develop two models to examine the relationship of smoking behavior on VO2max. GLM #1(without smoking) determined the combined effects of age, gender, PASS and BMI on VO2max. GLM #2 (with smoking) determined the added effects of smoking (pack.y groupings) on VO2max after controlling for age, gender, PASS and BMI. Constant errors (CE) were calculated to compare the accuracy of the two models for estimating the VO2max of the smoking subgroups. RESULTS: ANOVA affirmed the mean VO2max of each pack.y grouping decreased significantly (psmoking exposure increased. GLM #1 showed that age, gender, PASS and BMI were independently related with VO2max (R2 = 0.642, SEE = 4.90, pSmoked, the effects on VO2max from Light and Regular smoking habits were -0.83 and -0.85 ml.kg- 1.min-1 respectively (psmoking on VO2max was -2.56 ml.kg- 1.min-1 (psmoking group in GLM #2 was smaller than the CE s of the smoking group counterparts in GLM #1. CONCLUSIONS: After accounting for the effects of gender, age, PASS and BMI the effect of habitual smoking on reducing VO2max is minimal, about 0.85 ml/kg/min, until the habit exceeds 20 pack.y at which point an additional decrease of 1.71 ml/kg/min is noted. Adding pack.y data improves the accuracy of predicting the VO2max of smokers.

  18. Lessons learnt in building VO resources: binding together several VO standards into an operational service

    OpenAIRE

    Chilingarian, Igor; Bonnarel, Francois; Louys, Mireille; Sidaner, Pierre Le

    2011-01-01

    The International Virtual Observatory Alliance (IVOA) developed numerous interoperability standards during the last several years. Most of them are quite simple to implement from the technical point of view and even contain "SIMPLE" in the title. Does it mean that it is also simple to build a working VO resource using those standards? Yes and no. "Yes" because the standards are indeed simple, and "no" because usually one needs to implement a lot more than it was thought in t...

  19. Behind the color switching in gasochromic VO2.

    Science.gov (United States)

    Chen, Jeng-Lung; Chang, Chun-Chieh; Ho, Ying-Kai; Chen, Chi Liang; Hsu, Chih-Chin; Jang, Wei-Luen; Wei, Da-Hua; Dong, Chung-Li; Pao, Chih-Wen; Lee, Jyh-Fu; Chen, Jin-Ming; Guo, Jinghua; Wu, Maw-Kuen

    2015-02-01

    Gasochromic VO2 thin films were fabricated by the sol-gel spin-coating technique. The results of X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy reveal that the origin of gasochromic coloration in VO2 is strongly related to the modulation of its structure and the electron-electron correlation. Upon gasochromic coloration, not only does the valence state change with the incorporation of hydrogen, but also the film undergoes the modification of the local atomic structure. The structural distortion varies the strength of hybridization of the O 2p-V 3d states and the bond distance of V-O and V-O varies. In the hydric process, the local atomic structure of VO2 changes from that of an un-symmetric to that of a symmetric V-O framework. The incorporated hydrogen adds electrons into the V 3d t2g orbital, enhancing the electron-electron correlation by reducing the V-V distance. This work presents a new physical insight in which the modulation of the electron-electron correlation is exploited to control the bleached and colored states, giving rise to the gasochromic phenomenon. The strong correlation among atomic spatial rearrangement, electronic structures, and transmittance supports a cooperative mechanism of the VO2 gasochromic transition. These results reveal a clear correlation between the dynamics of the lattice structure and the electronic properties and suggest a possible pathway to gasochromism and elucidation of its mechanism. PMID:25533311

  20. Lessons learnt in building VO resources: binding together several VO standards into an operational service

    CERN Document Server

    Chilingarian, Igor; Louys, Mireille; Sidaner, Pierre Le

    2011-01-01

    The International Virtual Observatory Alliance (IVOA) developed numerous interoperability standards during the last several years. Most of them are quite simple to implement from the technical point of view and even contain "SIMPLE" in the title. Does it mean that it is also simple to build a working VO resource using those standards? Yes and no. "Yes" because the standards are indeed simple, and "no" because usually one needs to implement a lot more than it was thought in the beginning of the project so the time management of the team becomes difficult. In our presentation we will start with a basic case of a simple spectral data collection. Then we will describe several examples of small" technologically advanced VO resources built in CDS and VO-Paris and will show that many standards are hidden from managers' eyes at the initial stage of the project development. The projects will be: (1) the GalMer database providing access to the results of numerical simulations of galaxy interactions; (2) the full spectr...

  1. Integrating the IA2 Astronomical Archive in the VO: The VO-Dance Engine

    Science.gov (United States)

    Molinaro, M.; Laurino, O.; Smareglia, R.

    2012-09-01

    Virtual Observatory (VO) protocols and standards are getting mature and the astronomical community asks for astrophysical data to be easily reachable. This means data centers have to intensify their efforts to provide the data they manage not only through proprietary portals and services but also through interoperable resources developed on the basis of the IVOA (International Virtual Observatory Alliance) recommendations. Here we present the work and ideas developed at the IA2 (Italian Astronomical Archive) data center hosted by the INAF-OATs (Italian Institute for Astrophysics - Trieste Astronomical Observatory) to reach this goal. The core point is the development of an application that from existing DB and archive structures can translate their content to VO compliant resources: VO-Dance (written in Java). This application, in turn, relies on a database (potentially DBMS independent) to store the translation layer information of each resource and auxiliary content (UCDs, field names, authorizations, policies, etc.). The last token is an administrative interface (currently developed using the Django python framework) to allow the data center administrators to set up and maintain resources. This deployment, platform independent, with database and administrative interface highly customizable, means the package, when stable and easily distributable, can be also used by single astronomers or groups to set up their own resources from their public datasets.

  2. Reactive evaporation of anomalous blue VO2

    International Nuclear Information System (INIS)

    Thin films of vanadium dioxide exhibit a thermally induced semiconductor-to-metal phase transition near 670 C. In most deposition conditions, the transition is accompanied by large changes in optical properties at infrared wavelengths, but with only slight visible contrast. Recently, reactive evaporation at high temperatures and in stringent process conditions of so-called blue VO2 has been reported [G. A. Nyberg and R. A. Buhrman, J. Vac. Sci. Technol. A 2, 301 (1984)]. These films exhibit a striking blue-to-red transition in transmitted light. In this paper, a new technique for thin-film growth of anomalous vanadium dioxide will be presented. The primary steps in the process are the reactive evaporation of vanadium oxide at ambient temperature followed by anneal in flowing oxygen. Optical and microstructural data for material deposited on sapphire and fused quartz substrates will be compared to standard vanadium oxide

  3. VOTA: a VO tool for asteroseismology

    Science.gov (United States)

    Rodrigo, C.; Solano, E.; Suarez, J. C.; Moya, A.; Hernandez, A.

    2011-11-01

    Ground-based photometric campaigns (OGLE, MACHO, ASAS), spectroscopic surveys (FEROS, UVES) as well as space missions (MOST, CoRoT, Kepler and, in the near future, PLATO) are providing information in the frequency domain for thousands of stars with a quality never reached before. It is thus crucial that the same leap forward is made in the asteroseismic modeling domain in order to properly interpret the observations. This requires an easy and efficient intercomparison among independent codes. most of the times developed with different formats and based on different physical assumptions. The Spanish Virtual Observatory is doing a pioneering work to ensure a fully interoperability among theoretical and observational datasets. In this context we have developed VOTA, an application in which, for the first time, asteroseismic models together with visualization tools are managed within VO.

  4. Optical properties for the Mott transition in VO2

    Directory of Open Access Journals (Sweden)

    Manil Kang

    2012-03-01

    Full Text Available The relationship between the first-order metal-insulator transition (MIT and the structural phase transition (SPT in VO2 film is analyzed by dielectric function, optical conductivity, plasma energy, and electrical conductivity. The MIT and SPT temperatures in VO2 films were approximately 68 and 75 °C, respectively, with an intermediate phase existing between 68 and 75 °C. The optical and electrical results indicate that the first-order MIT in VO2 films is not driven by the SPT.

  5. GIPSY 3D: Analysis, visualization and VO-Tools

    Science.gov (United States)

    Ruíz, J. E.; Santander-Vela, J. D.; Espigares, V.; Verdes-Montenegro, L.; van der Hulst, J. M.

    2009-07-01

    The scientific goals of the AMIGA project are based on the analysis of a significant amount of spectroscopic 3D data. In order to perform this work we present an initiative to develop a new VO compliant package, including present core applications and tasks offered by the Groningen Image Processing System (GIPSY), and new ones based on use cases elaborated in collaboration with advanced users. One of the main goals is to provide local interoperability between GIPSY (visualization and data analysis) and other VO software. The connectivity with the Virtual Observatory environment will provide general access to 3D data VO archives and services, maximizing the potential for scientific discovery.

  6. Gipsy 3D: Analysis, Visualization and Vo-Tools

    CERN Document Server

    Ruiz, J E; Espigares, V; Verdes-Montenegro, L; Van der Hulst, J M

    2009-01-01

    The scientific goals of the AMIGA project are based on the analysis of a significant amount of spectroscopic 3D data. In order to perform this work we present an initiative to develop a new VO compliant package, including present core applications and tasks offered by the Groningen Image Processing System (GIPSY), and new ones based on use cases elaborated in collaboration with ad- vanced users. One of the main goals is to provide local interoperability between GIPSY (visualization and data analysis) and other VO software. The connectivity with the Virtual Observatory environment will provide general access to 3D data VO archives and services, maximizing the potential for scientific discovery.

  7. GIPSY 3D: Analysis, Visualization and VO Tools for Datacubes

    Science.gov (United States)

    Ruíz, J. E.; Santander-Vela, J. D.; Espigares, V.; Verdes-Montenegro, L.; van der Hulst, J. M.

    2009-09-01

    The scientific goals of the AMIGA project are based on the analysis of a significant amount of spectroscopic 3D data. In order to perform this work we present an initiative to develop a new VO compliant package, including present core applications and tasks offered by the Groningen Image Processing System (GIPSY), and new ones based on use cases elaborated in collaboration with advanced users. One of the main goals is to provide local interoperability between GIPSY and other VO software. The connectivity with the Virtual Observatory environment will provide general access to 3D data VO archives and services, maximizing the potential for scientific discovery.

  8. The VO-Neural project: recent developments and some applications

    CERN Document Server

    Brescia, M; d'Angelo, G; D'Abrusco, R; Deniskina, N; Garofalo, M; Laurino, O; Longo, G; Nocella, A; Skordovski, B

    2008-01-01

    VO-Neural is the natural evolution of the Astroneural project which was started in 1994 with the aim to implement a suite of neural tools for data mining in astronomical massive data sets. At a difference with its ancestor, which was implemented under Matlab, VO-Neural is written in C++, object oriented, and it is specifically tailored to work in distributed computing architectures. We discuss the current status of implementation of VO-Neural, present an application to the classification of Active Galactic Nuclei, and outline the ongoing work to improve the functionalities of the package.

  9. The Ingenious Structure of Central Rotor Apparatus in VoV1; Key for Both Complex Disassembly and Energy Coupling between V1 and Vo.

    Science.gov (United States)

    Nakanishi, Atsuko; Kishikawa, Jun-Ichi; Tamakoshi, Masatada; Yokoyama, Ken

    2015-01-01

    Vacuolar type rotary H+-ATPases (VoV1) couple ATP synthesis/hydrolysis by V1 with proton translocation by Vo via rotation of a central rotor apparatus composed of the V1-DF rotor shaft, a socket-like Vo-C (eukaryotic Vo-d) and the hydrophobic rotor ring. Reconstitution experiments using subcomplexes revealed a weak binding affinity of V1-DF to Vo-C despite the fact that torque needs to be transmitted between V1-DF and Vo-C for the tight energy coupling between V1 and Vo. Mutation of a short helix at the tip of V1-DF caused intramolecular uncoupling of VoV1, suggesting that proper fitting of the short helix of V1-D into the socket of Vo-C is required for tight energy coupling between V1 and Vo. To account for the apparently contradictory properties of the interaction between V1-DF and Vo-C (weak binding affinity but strict requirement for torque transmission), we propose a model in which the relationship between V1-DF and Vo-C corresponds to that between a slotted screwdriver and a head of slotted screw. This model is consistent with our previous result in which the central rotor apparatus is not the major factor for the association of V1 with Vo (Kishikawa and Yokoyama, J Biol Chem. 2012 24597-24603). PMID:25756791

  10. La biomasa de los cultivos en el oecosistema. Sus beneficios agroecológicos / The biomass of the cultivations in the agroecosistema. Its benefits agroecological

    Scientific Electronic Library Online (English)

    Anirebis, Martínez Romero; Angel, Leyva Galán.

    2014-03-01

    Full Text Available La biomasa es el resultado de la transformación de la energía solar en energía química. El hombre a través de la historia la ha utilizado no solo para su alimentación sino también para la alimentación de sus animales. Los avances de la ciencia promovieron el desarrollo agrario basado en la revolució [...] n verde, la cual solo promueve la producción de alimentos ya sea de uso humano o animal, marginando la importancia de la biomasa como enriquecedor del recurso suelo al disponerse de los insumos necesarios para sustituir su fertilidad natural. En la actualidad la producción y conservación de la biomasa de cualquier cultivo cobra una importancia trascendente; por que ello contribuye, además, a la protección medioambiental a través de la captura de carbono. El presente trabajo tuvo como objetivo demostrar la importancia que proporciona la biomasa generalmente no alimenticia para los humanos, a fin de emplearla no solo como alimento animal, sino también como enriquecedora del recurso natural suelo. Las investigaciones realizadas en Cuba sobre el tema es pobre, aun cuando en la actualidad resulta de gran importancia encontrar variantes que permitan profundizar en la producción de biomasa en su relación con el medio ambiente. Finalmente se exponen los resultados preliminares sobre producción de biomasa a partir de la agrobiodiversidad presente en los escenarios productivos, a la vez que se reflexiona sobre la importancia del tema para futuras investigaciones. Abstract in english Biomass is the result of the transformation of solar energy into chemical energy. The man throughout history has used not only for food but also for feeding their animals. The progress of science promoted agricultural development based on the green revolution, which only promotes the production of e [...] ither food or feed, marginalizing the importance of biomass as enriching the soil resources available inputs needed to replace their fertility natural. At present the production and preservation of any crop biomass becomes transcendent importance, because it also contributes to environmental protection through carbon sequestration. This study aimed to show the importance of providing non-food biomass generally for humans to use it not only as animal feed but also as a natural resource rich soil. Research in Cuba on the subject is poor, even though today is very important to find alternatives to deepen in the production of biomass in relation to the environment. Finally, we present preliminary results on the production of biomass from agricultural biodiversity present in production scenarios, while reflecting on the important question for future research.

  11. Effects of Na content on the luminescence behavior, conduction type, and crystal structure of Na-doped ZnO films

    Science.gov (United States)

    Lai, Jian-Jhong; Lin, Yow-Jon; Chen, Ya-Hui; Chang, Hsing-Cheng; Liu, Chia-Jyi; Zou, Yi-Yan; Shih, Yu-Tai; Wang, Meng-Chieh

    2011-07-01

    This study investigates the effect of Na content on the structural, optical, and electrical properties of sol-gel Na-doped ZnO films using x-ray diffraction, photoluminescence, and conductivity measurements. It is shown that a p-type conversion of the Na-doped ZnO film might be due to a combined effect of the increased substitutional-Na density and the decreased oxygen-vacancy (VO) density. However, excess Na incorporation into ZnO shows an ambiguous carrier type due to the increase in the donorlike VO density. These results indicate that compensation effects limit the hole concentration in the Na-doped ZnO films. In addition, when more Na is substituted into the ZnO system, the difference in the ionic radii of Zn2+ and Na+ starts playing an increasingly important role, causing the presence of tensile stress in the Na-doped ZnO film.

  12. VO Crawler: A Crawling System for Virtual Observatory Services

    Science.gov (United States)

    Komiya, Y.; Shirasaki, Y.; Ohishi, M.; Eguchi, S.; Mizumoto, Y.; Ishihara, Y.; Tsutsumi, J.; Hiyama, T.; Nakamoto, H.; Sakamoto, M.

    2012-09-01

    We report on the development of VO Crawler under the Japanese Virtual Observatory (JVO) project. VO Crawler accesses Virtual Observatory (VO) Services around the world, and caches data over the whole sky. As all the data are managed in a single system, it is able to do a quick search among the huge amount of data and to display the footprint where observation data exist on a sky map. We are developing applications which utilize data stored by the VO Crawler: JVO Sky which displays the stored data on a sky map, Whole Sky Search system which finds objects from multi-band data on the whole sky, and My Catalog Builder which assists one to build custom-made catalogs from the stored data.

  13. Density functional theory study of rutile VO2 surfaces

    CERN Document Server

    Mellan, Thomas A

    2012-01-01

    We present the results of a density functional theory (DFT) investigation of the surfaces of rutile-like vanadium dioxide, VO2(R). We calculate the surface energies of low Miller index planes, and find that the most stable surface orientation is the (110). The equilibrium morphology of a VO2(R) particle has an acicular shape, laterally confined by (110) planes and topped by (011) planes. The redox properties of the (110) surface are investigated by calculating the relative surface free energies of the non-stoichiometric compositions as a function of oxygen chemical potential. It is found that the VO2(110) surface is oxidized with respect to the stoichiometric composition, not only at ambient conditions but also at the more reducing conditions under which bulk VO2 is stable in comparison with bulk V2O5. The adsorbed oxygen forms surface vanadyl species much more favorably than surface peroxo species.

  14. Enhanced optical response of hybridized VO?/graphene films.

    Science.gov (United States)

    Kim, Hyeongkeun; Kim, Yena; Kim, TaeYoung; Jang, A-Rang; Jeong, Hu Young; Han, Seung Ho; Yoon, Dae Ho; Shin, Hyeon Suk; Bae, Dong Jae; Kim, Keun Soo; Yang, Woo Seok

    2013-04-01

    Application of graphene as transparent electrodes is an active research area due to its excellent electrical and optical properties. Vanadium dioxide (VO2) is an attractive material since it is a thermochromic material that undergoes a structural phase transition when heat is applied. The phase transition results in the change of electrical and optical characteristics. We report optical characteristics of hybrid materials of graphene and VO2. We observed a 12% improvement in infrared transmittance with VO2 films deposited on graphene sapphire substrates compared to that of bare sapphire substrates. We also found that the phase transition temperature decreases as the number of graphene layers on the substrates increases. In the case of VO2 films on the substrate that was coated with four layers of graphene, the mean phase transition temperature was lowered to ?56 °C. PMID:23443615

  15. Enhanced optical response of hybridized VO2/graphene films

    Science.gov (United States)

    Kim, Hyeongkeun; Kim, Yena; Kim, Taeyoung; Jang, A.-Rang; Jeong, Hu Young; Han, Seung Ho; Yoon, Dae Ho; Shin, Hyeon Suk; Bae, Dong Jae; Kim, Keun Soo; Yang, Woo Seok

    2013-03-01

    Application of graphene as transparent electrodes is an active research area due to its excellent electrical and optical properties. Vanadium dioxide (VO2) is an attractive material since it is a thermochromic material that undergoes a structural phase transition when heat is applied. The phase transition results in the change of electrical and optical characteristics. We report optical characteristics of hybrid materials of graphene and VO2. We observed a 12% improvement in infrared transmittance with VO2 films deposited on graphene sapphire substrates compared to that of bare sapphire substrates. We also found that the phase transition temperature decreases as the number of graphene layers on the substrates increases. In the case of VO2 films on the substrate that was coated with four layers of graphene, the mean phase transition temperature was lowered to ~56 °C.Application of graphene as transparent electrodes is an active research area due to its excellent electrical and optical properties. Vanadium dioxide (VO2) is an attractive material since it is a thermochromic material that undergoes a structural phase transition when heat is applied. The phase transition results in the change of electrical and optical characteristics. We report optical characteristics of hybrid materials of graphene and VO2. We observed a 12% improvement in infrared transmittance with VO2 films deposited on graphene sapphire substrates compared to that of bare sapphire substrates. We also found that the phase transition temperature decreases as the number of graphene layers on the substrates increases. In the case of VO2 films on the substrate that was coated with four layers of graphene, the mean phase transition temperature was lowered to ~56 °C. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34054f

  16. Producción de biomasa de Saccharomyces cerevisiae y Candida utilis usando residuos de pulpa de Coffea arabica L

    Scientific Electronic Library Online (English)

    María J, Gualtieri A; Carolina, Villalta R; Lorena E, Díaz T; Gerardo, Medina; Elisa, Lapenna; María E, Rondón.

    2007-12-01

    Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish Los avances en biotecnología industrial ofrecen oportunidades potenciales para la utilización económica de residuos agro-industriales tales como la pulpa de café, material mucilaginoso, fibroso (producto secundario) obtenido durante el proceso húmedo o seco del beneficio de las cerezas de café. El p [...] ropósito de este trabajo fue utilizar los residuos de la pulpa de café, rico en materia orgánica, como sustrato para la producción de biomasa de levaduras por procesos de fermentación aeróbica. Los residuos de café se sometieron a hidrólisis con una solución de ácido sulfúrico al 2%, en una relación 10:1 (líquido:sólido), con un tamaño de partícula ? 2 mm., operando a presión atmosférica, ebullición a reflujo, durante 4 horas. El extracto ácido se filtró y se ajustó a pH 4,5 y luego se esterilizó a 120 ºC por 15 minutos. La fermentación se realizó con Saccharomyces cerevisiae y Candida utilis, medio de producción extracto de café enriquecido con sales nutritivas. Se formularon diferentes medios de producción (1,2,3 y 4), siendo el N°3, enriquecido con extracto de café hidrolizado, 1L; urea, 3g/L; fosfato ácido de potasio, 2g/L; extracto de malta, 1,3g/L y melaza, 30g/L, el cual aportó los mejores resultados. El tiempo total de fermentación fue de 8 horas. Se obtuvo 10g/L de biomasa con un incremento proteico de 7,39 a 42,5%. Se puede concluir que la pulpa de café constituye un sustrato adecuado para obtener biomasa o proteína unicelular, que podría ser destinada como suplemento en formulaciones para alimentación animal Abstract in english The advances in industrial biotechnology offer potential opportunities for the economic use of agro-industrial remainders such as the coffee pulp, mucilagenous, fibrous material (secondary product) obtained during the humid or dry process of the benefit of the coffee cherries. The intention of this [...] work was to use the remainders of the pulp of coffee, rich in organic matter, like substrate for the production of biomass of leavenings by processes of aerobic fermentation. The coffee remainders were put under hydrolysis with a sulfuric acid solution to 2%, in a 10:1 relation (liquid: solid), with a size of particle ? 2 mm, operating to atmospheric pressure, boiling to ebb tide, during 4 hours. The acid extract filtered and it adjusted to pH 4,5 and then it sterilize to 120 ºC by 15 minutes. The fermentation was made with Saccharomyces cerevisiae and Candida utilis, the production means: extract of coffee enriched with nutritious salts. Different means from production were formulated (1,2,3 and 4), being the N°3, enriched with extract of hydrolyzed coffee, 1L; urea, 3g/L; acid potassium phosphate, 2g/L; extract of Malta, 1,3g/L and molasses, 30g/L, which contributed the best results. The total time of fermentation was of 8 hours. 10g/L of biomass with a protein increase from 7.39 to 42.5% was obtained. It is possible to be concluded that the coffee pulp constitutes an suitable substrate to obtain biomass or unicellular protein, that could be destined like supplement in formulations for feeding animal

  17. Fair Scheduling for Delay-Sensitive VoIP Traffic

    Science.gov (United States)

    Ahmed, Shawish; Jiang, Xiaohong; Horiguchi, Susumu

    With the wide expansion of voice services over the IP networks (VoIP), the volume of this delay sensitive traffic is steadily growing. The current packet schedulers for IP networks meet the delay constraint of VoIP traffic by simply assigning its packets the highest priority. This technique is acceptable as long as the amount of VoIP traffic is relatively very small compared to other non-voice traffic. With the notable expansion of VoIP applications, however, the current packet schedulers will significantly sacrifice the fairness deserved by the non-voice traffic. In this paper, we extend the conventional Deficit Round-Robin (DRR) scheduler by including a packet classifier, a Token Bucket and a resource reservation scheme and propose an integrated packet scheduler architecture for the growing VoIP traffic. We demonstrate through both theoretical analysis and extensive simulation that the new architecture makes it possible for us to significantly improve the fairness to non-voice traffic while still meeting the tight delay requirement of VoIP applications.

  18. Análisis de la biomasa de raíces en diferentes tipos de bosques: Avances en la evaluación de Pinus radiata en Chile Root biomass analysis in different forest types: research advances in the Chilean radiata pine forest

    OpenAIRE

    Javier Guerra, C.; Jorge Gayoso, A.; Juan Schlatter, V.; Roberto Nespolo, R.

    2005-01-01

    Se evaluó la biomasa de raíces en la especie Pinus radiata (D. Don) en dos condiciones de sitio diferentes en Chile central, utilizando el índice raíz/vástago (proporción de raíces respecto de la biomasa aérea). Además, se analizó literatura referida a la proporción de sistemas radicales con el propósito de inferir el efecto de especies y medio ambiente sobre el desarrollo de raíces. Se cosecharon 27 individuos de Pinus radiata de diferentes edades en un rango de 3 hasta 23 años...

  19. Modelos para estimar la biomasa de especies nativas en plantaciones y bosques secundarios en la zona Caribe de Costa Rica Models for biomass estimation in native forest tree plantations and secondary forests in the Costa Rican Caribbean Region

    OpenAIRE

    William Fonseca G; Federico Alice G; José María Rey B

    2009-01-01

    El uso de los ecosistemas forestales como sumideros y reservorios de carbono es cada día más aceptado. Aún así, la información fidedigna sobre su crecimiento en biomasa y la capacidad de captura y de almacenamiento de CO2 es insuficiente para proponer formas de compensación a los propietarios de bosques. El objetivo de este trabajo fue construir modelos para estimar la biomasa del árbol en plantaciones de Hieronyma alchorneoides, Vochysia guatemalensis y para un grupo de 35 especies en...

  20. REDUCCIÓN DE LA BIOMASA DEL PINO CARRASCO (PINUS HALEPENSIS EN UN ÁREA DEL SURESTE SEMIÁRIDO PENINSULAR COMO ESTRATEGIA PARA EVITAR EL ESTRÉS HÍDRICO

    Directory of Open Access Journals (Sweden)

    Francisco Belmonte Serrato

    2008-01-01

    Full Text Available En las épocas de fuertes sequías, la vegetación mediterránea sufre un estado de estrés hídrico prolongado que le obliga a adoptar diversas estrategias de supervivencia, entre las que fi guran, como último recurso, y antes de llegar a superar su capacidad de resilencia, la reducción de la biomasa de hojas. En este trabajo se pone de manifi esto como algunos ejemplares de Pinus halepensis existentes en el área de estudio (el campo experimental de El Ardal, Murcia, redujeron apreciablemente su biomasa aérea en respuesta a la sequía, que se manifestó en un importante aumento de la producción de hojarasca. La producción de hojarasca se relaciona además de con la precipitación registrada en el periodo de estudio, con la humedad del suelo, parámetro clave en la supervivencia de la vegetación en ambientes secos.

  1. Synthesis and properties of solid solutions with perovskite structure in the SrVO3-EuVO3 system

    International Nuclear Information System (INIS)

    Investigation results of solid solutions Srsub(1-x)Eusub(x)VOsub(3) where a noticeable presence of defects in anion sublattice are presented. Solid solutions shown, are obtained by sintering of strontium hypovanadate SrVO3 and europium orthovanadate EuVO3 in vacuum at 1673 K during 36 hours. Existence of Srsub(1-x)Eusub(x)VOsub(3) solid solutions with the perovskite structure of two types: cubic (03-EuVO3 system. It is shown that in Srsub(1-x)Eusub(x)VOsub(3) solid solutions, as well as in EuVO3, three-valent state of Eu is preserved. Transition from the metal conductivity character to the semiconductive one is carrierd out at xsub(k) approximately 0.75. Concentration and temperature dependences of specific electric resistance of solid solutions are presented

  2. Variaciones de abundancia y biomasa del zooplancton en un embalse tropical oligo-mesotrófico del norte de Venezuela

    Scientific Electronic Library Online (English)

    Sandra, Merayo; Ernesto J, González.

    2010-06-01

    Full Text Available SciELO Costa Rica | Language: Spanish Abstract in spanish La abundancia del zooplancton en los embalses está determinada principalmente por la velocidad y el contenido del agua, pero se sabe relativamente poco sobre los embalses tropicales. Se estudió la distribución temporal y espacial de la abundancia y la biomasa del zooplancton en el eje longitudinal d [...] el embalse de Clavellinos, en el norte de Venezuela, entre octubre 2006 y septiembre 2007. El zooplancton fue recolectado en el estrato oxigenado con una red de plancton. Un total de 16 taxones fueron identificados: Copepoda, Cladocera, Rotifera, Ostracoda y Diptera. Thermocyclops decipiens (Copepoda, Cyclopoida) dominó la comunidad, mientras que los rotíferos fueron los más diversos, con 10 especies. La abundancia del zooplancton varió de 31 a 101ind/l en E1, 36 a 84ind/l en E2, y, de 30 a 250ind/L en el E3. La biomasa varió de 97,4 a 1406.3?g/l en E1, 108,5 a 397.2?g/l en E2, y de 25,9 a 763.9?g/l en el E3. Esta comunidad de zooplancton pareci? responder a las variaciones ambientales en el embalse, m?s que a las variaciones en la disponibilidad de recursos. Abstract in english Variations of zooplankton abundance and biomass in a tropical oligo-mesotrophic reservoir in Northern Venezuela. Zooplankton abundance in reservoirs is mainly determined by the speed and content of the water, but relatively little is known regarding tropical reservoirs. We studied the seasonal and s [...] patial distribution of zooplankton abundance and biomass along the longitudinal axis of Clavellinos reservoir, northern Venezuela, from October 2006 to September 2007. Zooplankton was collected from the oxygenated layer using a plankton net. A total of 16 taxa were identified: Copepoda, Cladocera, Rotifera, Ostracoda and Diptera. Thermocyclops decipiens (Copepoda, Cyclopoida) dominated the community, while rotifers were the most diverse, with 10 species. Zooplankton abundance varied from 31 to 101ind/L in E1, 36 to 84ind/L in E2, and, from 30 to 250ind/L in E3. Biomass varied from 97.4 to 1406.3?g/l in E1, 108.5 to 397.2?g/l in E2, and from 25.9 to 763.9?g/l in E3. This zooplankton community seems to respond to environmental variations in the reservoir, rather than to variations in resource availability. Rev. Biol. Trop. 58 (2): 603-619. Epub 2010 June 02.

  3. Variaciones de abundancia y biomasa del zooplancton en un embalse tropical oligo-mesotrófico del norte de Venezuela

    Directory of Open Access Journals (Sweden)

    Sandra Merayo

    2010-06-01

    Full Text Available La abundancia del zooplancton en los embalses está determinada principalmente por la velocidad y el contenido del agua, pero se sabe relativamente poco sobre los embalses tropicales. Se estudió la distribución temporal y espacial de la abundancia y la biomasa del zooplancton en el eje longitudinal del embalse de Clavellinos, en el norte de Venezuela, entre octubre 2006 y septiembre 2007. El zooplancton fue recolectado en el estrato oxigenado con una red de plancton. Un total de 16 taxones fueron identificados: Copepoda, Cladocera, Rotifera, Ostracoda y Diptera. Thermocyclops decipiens (Copepoda, Cyclopoida dominó la comunidad, mientras que los rotíferos fueron los más diversos, con 10 especies. La abundancia del zooplancton varió de 31 a 101ind/l en E1, 36 a 84ind/l en E2, y, de 30 a 250ind/L en el E3. La biomasa varió de 97,4 a 1406.3?g/l en E1, 108,5 a 397.2?g/l en E2, y de 25,9 a 763.9?g/l en el E3. Esta comunidad de zooplancton pareci? responder a las variaciones ambientales en el embalse, m?s que a las variaciones en la disponibilidad de recursos.Variations of zooplankton abundance and biomass in a tropical oligo-mesotrophic reservoir in Northern Venezuela. Zooplankton abundance in reservoirs is mainly determined by the speed and content of the water, but relatively little is known regarding tropical reservoirs. We studied the seasonal and spatial distribution of zooplankton abundance and biomass along the longitudinal axis of Clavellinos reservoir, northern Venezuela, from October 2006 to September 2007. Zooplankton was collected from the oxygenated layer using a plankton net. A total of 16 taxa were identified: Copepoda, Cladocera, Rotifera, Ostracoda and Diptera. Thermocyclops decipiens (Copepoda, Cyclopoida dominated the community, while rotifers were the most diverse, with 10 species. Zooplankton abundance varied from 31 to 101ind/L in E1, 36 to 84ind/L in E2, and, from 30 to 250ind/L in E3. Biomass varied from 97.4 to 1406.3?g/l in E1, 108.5 to 397.2?g/l in E2, and from 25.9 to 763.9?g/l in E3. This zooplankton community seems to respond to environmental variations in the reservoir, rather than to variations in resource availability. Rev. Biol. Trop. 58 (2: 603-619. Epub 2010 June 02.

  4. BIOMASA, DENSIDAD Y COMPOSICION ZOOPLANCTONICA DE LA BAHIA DE MOCHIMA, VENEZUELA Zooplankton biomass, density and composition in Mochima Bay, Venezuela

    Directory of Open Access Journals (Sweden)

    Brightdoom Márquez-Rojas

    2008-06-01

    Full Text Available La biomasa, densidad y composición del zooplancton de la bahía de Mochima fueron estudiadas durante 1998. Las muestras fueron recolectadas mensualmente en la entrada de la bahía (estación A y en la parte interna (estación B entre enero y diciembre de 1998. En cada estación se realizaron calados oblicuos con una malla estándar de 300 micras y 0,25 m de diámetro de boca a 0-5 y 10-15 m y a una velocidad de dos nudos durante 10 min. El índice de surgencia se calculó a partir de los datos de vientos. Se midió salinidad, temperatura del agua, concentración de oxígeno disuelto, concentración de clorofila a, biomasa y densidad del zooplancton; además se identificaron los organismos, en lo posible hasta especie. Los perfiles de temperatura mostraron un mayor tiempo de permanencia de aguas cálidas superficiales en la estación más interna. Los valores más altos de densidad zooplanctónica (4066 ind/m³ se registraron en el período febrero - mayo y luego los valores fueron relativamente bajos (Zooplankton biomass, density and composition were studied in Mochima Bay during 1998. Samples were collected at monthly intervals at stations located at the mouth and the interior of the bay from January to December 1998. At each station, samples were collected in the intervals 0-5 and 10-15 m with a Standard net of 300 µm and 0,25 m Ø at a speed of two knots during ten minutes. Wind data was used to calculate the upwelling index. Salinity, water temperature, concentration of dissolved oxygen and chlorophyll a (chl a, and zooplankton biomass and density were measured at the two stations. Also, the organisms were identified to group level. Temperature profiles showed a greater residence time for warm waters in the internal part of the bay than in the external one. Higher zooplankton density values (4066 ind/m³ were found during the period February - May. Values were relatively low (< 200 ind/m³ in June and July for both stations. They were also low for the external station in the period October - December. The highest zooplankton density was measured in the layer 10-15m in the internal station. Dominance pattern was similar for both stations. Eighteen zooplankton groups were identified. The order of importance of the groups in terms of relative abundance was copepods, apendiculates, balanid nauplii and cladocerans. The latter dominated from July to September (warm-water period at the internal station. The variation in zooplankton density and composition reflected a strong influence of the upwelling index and of water temperature.

  5. Efecto de fertilización nitrogenada en la producción de biomasa y calidad de aceite esencial en Lippia alba (Miller, Pronto alivio.

    Directory of Open Access Journals (Sweden)

    Sánchez O. M.

    2004-04-01

    Full Text Available En el Campo Experimental de la Universidad Nacional de Colombia sede Palmira (CEUNP se realizó un ensayo para evaluar el efecto de la fertilización nitrogenada, aplicando dos fuentes (gallinaza y urea en dos niveles (50 y 100 kg/ha de nitrógeno y dos frecuencias de corte (dos y cuatro meses. En el lote experimental se situaron 15 parcelas, en un diseño de bloques completos al azar, con cinco tratamientos y tres repeticiones. Para el análisis de la información se utilizó el programa estadístico SAS. El máximo rendimiento de biomasa y aceites esenciales se obtuvo con la aplicación de 100 kg/ha de nitrógeno en forma de urea y la frecuencia de corte cada dos meses. Los niveles de extracción de Lippia alba en nitrógeno variaron entre 79.7 y 128.5; fósforo entre 24.5 y 30.5; potasio entre 114.6 y 138.8 y calcio entre 100 y 150 kg/ha. El aceite esencial estuvo compuesto mayoritariamente por carvona y limoneno. Palabras claves: Fertilización nitrogenada, Lippia alba, Rendimientos biomasa, aceites esenciales, pronto alivio. ABSTRACT Nitrogenous fertilization effects in the Lippia alba production and quality. In the Experimental Center of the National University of Colombia-Palmira (CEUNP a experiment was realized to evaluate the effect of the nitrogenous fertilization, using two sources (gallinaza and urea at two levels (50 and 100 kg/ha of nitrogen and two cutting frequencies (each two and four months. In the experimental area 15 plots were planted, in a randomized Complete Blocks design random (RCBD with five treatments and three repetitions to measure the following variables: production of fresh matter, content of dry matter, nutrients extraction and content of essential oils. The analysis of variance used the statistical program SAS. The maximum yield of biomass and essential was obtained oils combining the fertilization with 100 kg/ha of nitrogen as urea and the cutting frequency every of two months. The levels of nutrients extraction of Lippia alba varied between 79.7 and 128.5 kg/ha of nitrogen, 24.5 and 30.5 kg/ha of phosphorus, 114.6 and 138.8 Kg/ha of potassium and between 100 y 150 kg/ha of Calcium. The phytochemical analyses showed that the essential oil was mainly composed by carvona and limoneno. Key words: Nitrogenous Fertilization, Lippia alba, yields, biomass, essential oils.

  6. Intestinal absorption and secretion of radioactive vanadium (48VO-3) in rats and effect of Al(OH)3

    International Nuclear Information System (INIS)

    Sprague-Dawley rats (180-300 g) were fasted overnight and gavaged with 5 ?mol Na3VO4 in 1.0 ml 0.9% NaCl containing 1 ?Ci 48V. Control animals (n = 12) simultaneously received 1.0 ml diluent and experimental animals (n = 12) received 1 ml Al(OH)3. Diluent and Al(OH)3 were then given daily for 4 d. Urine and feces were collected separately each day. In control animals total 48V recovery (stool and urine) over 4 d was 86.6 +/- 2.4% of the administered dose. Although Al(OH)3 insignificantly increased total 48V recovery (93.6 +/- 3.2%), it markedly increased excretion of 48V in the stool as compared to the urine (control:stool, 69.1 +/- 1.8%; urine, 12.5 +/- 1.3%; Al(OH)3:stool, 85.7 +/- 1.5%; urine, 7.9 +/- 1.8%). Animals were then sacrificed and tissue uptake of tracer measured. The pattern of unexcreted 48V in tissues of both groups was kidney > bone > liver > intestine > muscle, but the tissue levels were uniformly higher in controls than in Al(OH)3-treated animals. The ability of Al(OH)3 to remove endogenous VO-3 was also examined. 48V was injected ip (n = 20). Half of the animals received diluent and half received 1.0 ml Al(OH)3 by gavage daily for 4 d. There were no differences in the pattern of 48V tissue distribution and excretion. It is concluded that Al(OH)3 may prconcluded that Al(OH)3 may prevent tissue accumulation of VO-3 from dietary sources by reducing intestinal VO-3 absorption

  7. Comunidades de peces de profundidad en el Mediterráneo y el Atlántico: diferencias en la composición de la biomasa y la estructura de tamaños

    OpenAIRE

    Massuti?, Enric; Gordon, John D. M.; Moranta, Joan; Swan, Sarah C.; Stefanescu, Constantino

    2004-01-01

    [ES] Los datos obtenidos a partir de 214 pescas de arrastre de fondo con un sólo cable, realizadas a lo largo de un período de veinte años en el Mediterráneo occidental (cuencas argelina y balear) y Atlántico nor-oriental (Rockall Trough y Porcupine Seabight), entre 402 y 1993 m de profundidad, han permitido una comparación estandarizada de la densidad y de la composición y estructura de tamaños de la biomasa, tanto del conjunto de la ictiofauna como de las principales esp...

  8. Flux-Czochralski growth of Ca9Y(VO4)7 crystal

    Science.gov (United States)

    Sun, Shijia; Zhang, Lizhen; Huang, Yisheng; Lin, Zhoubin; Wang, Guofu

    2014-04-01

    The mutual solubility of Ca9Y(VO4)7 and Li3VO4 was investigated in detail, Ca9Y(VO4)7 has high solubility in Li3VO4. Based on this, a high-quality Ca9Y(VO4)7 crystal was grown successfully by the Flux-Czochralski method from Li3VO4 flux. The thermal conductivity, thermal expansion coefficient, optical transmittance and crystal defect of the grown Ca9Y(VO4)7 crystal were measured, and compared with those of the Ca9Y(VO4)7 crystal grown by the traditional Czochralski method. The results show that the Ca9Y(VO4)7 crystal grown by the Flux-Czochralski method has much higher optical quality, and the Flux-Czochralski method is suitable to the growth of vanadate crystals.

  9. Chemical and sonochemical approaches to the formation of VO{sub 2} films and VO{sub 2}-impregnated materials

    Energy Technology Data Exchange (ETDEWEB)

    Keppens, V.; Mandrus, D.; Boatner, L.A. [Oak Ridge National Lab., TN (United States). Solid State Div.

    1997-11-01

    A new chemical and chemical/ultrasonic approach to the preparation of VO{sub 2} films and VO{sub 2}-impregnated bulk materials has been developed. In this approach, a V{sub 2}O{sub 5} sol prepared by quenching is used to coat SiO{sub 2} substrates. The resulting gel-film is heat treated in a reducing atmosphere to form a film identified as VO{sub 2} from the results of X-ray diffraction and both optical and resistivity measurements, which reveal the phase transition characteristic of vanadium dioxide. The advantage of this approach to the formation of VO{sub 2} is that the V{sub 2}O{sub 5} sol can be used to impregnate porous materials, which are then heated treated to form an optically active composite material. The switching properties of the VO{sub 2} films are investigated using optical and resistivity measurements, and the results are compared to those obtained for VO{sub 2}-films prepared by more-conventional methods.

  10. VoLTE performance in railway scenarios

    DEFF Research Database (Denmark)

    Sniady, Aleksander; SØnderskov, Morten

    2015-01-01

    GSM-Railways (GSM-R) is the current standard for railway voice and data communication. GSM-R provides railway specific voice services, such as Railway Emergency Call (REC). GSM-R provides also the European Train Control System (ETCS), which offers in-cab signaling and Automatic Train Protection (ATP). Despite these features and services, GSM-R has various major shortcomings. Therefore, alternative technologies are considered to replace GSM-R and become the next generation railway mobile communication network. 3GPP Long Term Evolution (LTE) is a likely candidate for GSM-R replacement. LTE is more efficient, flexible and offers much higher capacity, which allows the railway network to provide new communication-based applications for railways. Most of the research on LTE in railways has been focused on data-based railway applications (ETCS signaling and other). Nevertheless, voice communication is still a crucial service for railways. Regardless of its advantages, LTE can only become a railway communication technology if it provides voice communication fulfilling railway requirements. This paper presents how Voice over LTE (VoLTE) can be used to build railway communication services. Examples of Railway Emergency Call and One-to-One Call are provided. Service performance, in terms of call setup times and voice transmission quality, is analyzed in simulation scenarios modelling two railway scenarios in Denmark.

  11. Abundancia y biomasa de macroinvertebrados edáficos en la temporada lluviosa, en tres usos de la tierra, en los Andes colombianos

    Directory of Open Access Journals (Sweden)

    Pardo Luis C

    2006-03-01

    Full Text Available COMPENDIO los usos evaluados fueron pastizal, cafetal y bosque secundario (Vereda Villa del Rosario, Aprox. 3º 33' 16â€? Latitud Norte y 76º 36' 01â€? Longitud Oeste, altitud 1.500 a 1.820m., precipitación 960 a 1.050 mm/año, 19.8 a 21.2º C con la metodología TSBF. Se implementaron tres monolitos por uso y cada uno se subdividió en cuatro estratos (hojarasca, 0-10 cm, 10-20 cm, y 20-30 cm, las variables densidad y biomasa por parcela y estrato se examinaron a través de ANOVAS y Post-Anovas. En abundancia la supremacía fue de hormigas (25584 ejemplares, miriápodos (4808 ejemplares y lombrices (1984 ejemplares, la diferencia significativa la marcaron los miriápodos (F=4.84, P=0.014 asociados con bosque y cafetal con sombrío. En biomasa los grupos más importantes fueron miriápodos (701.05 g m-2, 58.71%, lombrices (90.64 g m-2; 7.59%, chisas (27.07 g m-2; 2.26% hor­migas (20.90 g m-2; 1.75% y arañas (15.71 g m-2 ; 1.31%, con diferencias significativas en hormigas (F=4.17, P=0.024 y arañas (F=3.43, P=0.4024; También hubo diferencias estadísticas significativas en la densidad y biomasa de macroinvertebrados y los estratos de los monolitos, los resultados indican que estos organismos expresan en su población y biomasa respuestas ambientales asociadas más con la estructura del agroecosistema que con la variación química, física o microbiológica del hábitat; se recomienda discriminar taxonómicamente los grupos funcionales y ampliar los muestreos a la temporada seca. Palabras clave: uso del suelo, macroinvertebrados edáficos, densidad, abundancia, agroecosistemas, Andes colombianos. ABSTRACT Abundance and biomass of soil macroinvertabrates during the rainy season in three land use systems in the Colombian Andes. Using the TSBF methodology, three land use systems—pastures, coffee plantation, and secondary forest— were evaluated in the rural community of Villa del Rosario, located in the municipality of Cali, Valle del Cauca, Colombia . This community is located at approximately 3º 33' 16 N and 76º 36' 01 W, with an altitude of 1.500-1.820 m above sea level, an annual precipitation of 960-1.050 mm, and temperatures ranging from 19.8 to 21.2º C. Three monoliths were used per land use system, each one subdivided into four strata (fallen leaves and 0-10 cm, 10-20 cm, and 20-30 cm in depth. The variables for density and biomass per plot and stratum were submitted to ANOVA and post-ANOVA comparison. Among macroin­vertebrates found, ants outnumbered the others by far with 25.584 individuals, followed by myriapods with 4808 individuals, and earthworms with 1984. A significant difference was found in the case of myriapods (F=4.84, P=0.014 in association with forest and coffee plantation under shade. In terms of biomass, the most important groups found were myriapods (701.05 g m-2, 58.71%, earthworms (90.64 g m-2, 7.59%, grubs (27.07 g m-2, 2.26%, ants (20.90 g m-2, 1.75%, and spiders (15.71 g m-2, 1.31%. Significant differences were found in the case of ants (F=4.17, P=0.024 and spiders (F=3.43, P=0.4024. Significant statistical differences were also found for density and biomass of macroinvertebrates and monolith strata. Results indicated that the environmental response of these organisms in terms of population and biomass is more associated to agroecosystem structure than to chemical, physical, or microbiological variation of the habitat. Functional groups should be taxonomically differentiated and samplings should be extended to the dry season. Key words: land use, soil macroinvertebrates, density, agroecosystems, Colombian Andes, biomass.

  12. Correlação entre as medidas direta e indireta do VO2max em atletas de futsal / Correlation between direct and indirect VO2max measurements in indoor soccer players / Correlación entre las medidas directa e indirecta del VO2max en atletas de futsal

    Scientific Electronic Library Online (English)

    Anna Myrna Jaguaribe de, Lima; Daniele Vanusca Gomes, Silva; Alexandre Oscar Soares de, Souza.

    2005-06-01

    Full Text Available A importância das qualidades morfofuncionais na melhora do rendimento nos esportes aumentou o interesse no aprimoramento dos níveis de aptidão física dos atletas. No entanto, há poucos estudos sobre as variáveis fisiológicas do futsal disponíveis na literatura científica mundial. Dessa forma, o obje [...] tivo deste estudo foi verificar a existência de correlação entre os testes de medida direta e indireta do VO2max, em jogadores de futsal. Foram analisados 13 jogadores de futsal, com idade de 18,6 ± 1,9 anos, altura igual a 177,1 ± 3,5cm, peso de 68,5 ± 9,5kg, índice de massa corporal (IMC) de 21,7 ± 2,3kg/m². Para medida direta do VO2max foi utilizado o sistema ergoespirométrico computadorizado (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) e para mensuração indireta do VO2max foi realizado o teste de campo de 3.200m. A análise estatística foi elaborada através do teste t de Student para amostras pareadas e pelo coeficiente de correlação de Pearson. Os valores de VO2max obtidos no teste de medida direta não apresentaram diferenças significativas em relação à medida indireta (62,8 ± 10,1 vs. 58,5 ± 8,5ml/kg/min, respectivamente). Quando correlacionados os valores de VO2max obtidos em ambos os testes, observou-se forte correlação (r = 0,72). Em conclusão, os testes de medida indireta apresentam boa aceitação para os atletas de futsal, tendo em vista a alta correlação com os testes de medida direta, o baixo custo de sua aplicação e o fornecimento de informações importantes que podem auxiliar na prescrição e no acompanhamento do treinamento. Abstract in spanish La importância de las cualidades morfo-funcionales en la mejora del rendimiento en los deportes aumentó el interes en el acondicionamiento de los niveles de aptitud física de los atletas. En tanto, hay pocos estudios sobre las variables fisiológicas del futsal disponibles en la literatura mundial. D [...] e esta forma, el objetivo del estudio fué verificar la existencia de la correlación entre los tests de medida directa e indirecta del VO2max, en jugadores de futsal. Fueron analizados 13 jugadores de futsal, con edades de entre 18,6 ± 1,9 años, altura igual a 177,1 ± 3,5 cm, peso de 68,5 ± 9,5 kg, índice de masa corporal (IMC) de 21,7 ± 2,3 kg/m². Para la medida directa del VO2max fué utilizado el sistema ergoespirométrico computadorizado (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) para mensura indirecta del VO2max fué realizado el test de campo de 3200m. El análisis estatístico fué elaborado a través del test t-Student para las muestras pareadas y por el coeficiente de correlación de Pearson. Los valores de VO2max obtenidos en el test de medida directa no presentaron diferencias significativas en relación a la medida indirecta (62,8 ± 10,1 vs. 58,5 ± 8,5 ml/kg/min, respectivamente). Cuando correlacionamos los valores de VO2max obtenidos en ambos tests, observamos una fuerte correlación (r = 0,72). En conclusión, los tests de medida indirecta presentaron buena aceptación para los atletas de futsal, teniendo en vista la alta correlación con los tests de medida directa, el bajo costo de su aplicación y el apercibimiento de las informaciones importantes que puedem auxiliar la prescrición de el no acompañamiento del entrenamiento. Abstract in english The importance of the morphofunctional qualities to greater efficiency in sports has increased the interest on the improvement on the physical fitness levels of athletes. However, not many studies on the physiological variables of indoor soccer are available in the world scientific literature. Thus, [...] the objective of this work was to verify the existence of correlation between the direct and indirect VO2max measurement tests in indoor soccer players. Thirteen indoor soccer players with age of 18.6 ± 1.9 years, height of 177.1 ± 3.5 cm, weight of 68.5 ± 9.5 kg and body mass index (BMI) of 21.7 ± 2.3 kg/m² were analyzed. For the direct VO2max measurement, the computerized ergospirometric system was us

  13. Conversión hidrotérmica subcrítica de residuos orgánicos y biomasa: Mecanismos de reacción / Subcritical hydrothermal conversion of organic wastes and biomass: Reaction pathways

    Scientific Electronic Library Online (English)

    Alejandro Amadeus, Castro Vega; Luis Ignacio, Rodríguez Varela; José de Jesús, Díaz Velásquez.

    2007-04-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish La conversión hidrotérmica es un procedimiento que emula el proceso natural de conversión de la materia orgánica en un biocrudo con propiedades físico-químicas similares a las del petróleo. La transformación artificial de biomasa requiere conocer previamente las rutas de reacción y productos prevale [...] ntes. En la conversión de celulosa, el principal componente de la biomasa, se presenta despolimerización por hidrólisis y se obtienen oligosacáridos, los cuales presentan deshidratación y condensación retro-aldol, para transformarse en furfurales y ácidos carboxílicos. Otros componentes de la biomasa como lignina, proteínas y ésteres grasos, presentan rutas de reacción en las que coexisten la hidrólisis y la pirólisis. Dada la presencia de carbohidratos en la biomasa, los principales productos de su conversión hidrotérmica subcrítica y de sus residuos serán análogos a los que presenta la celulosa. Dichas sustancias tienen un valor agregado que supera considerablemente los costos de adquisición de la materia prima. Al representar en un gráfico las relaciones molares O/C, H/C de los principales productos de conversión hidrotérmica de biomasa reportados en la literatura, se evidencia que la trayectoria de evolución para los productos de conversión hacia biocrudos se traslapa con la evolución geológica de los combustibles fósiles. Abstract in english Hydrothermal conversion is a procedure which emulates organic matter’s natural conversion into bio-crude having physical and chemical properties analogous to petroleum. The artificial transformation of biomass requires previous knowledge of the main reaction routes and product availability. The main [...] component of biomass (depolymerisation by hydrolysis) is presented in hydrothermal cellulose conversion, producing oligosaccharides which exhibit dehydration and retro-aldol condensation reactions for transforming into furfurals and carboxylic acids. Other biomass components (such as lignin, proteins, and fat esters) present both hydrolysis and pyrolysis reaction routes. As long as biomass mainly contains carbohydrates, subcritical hydrothermal conversion products and their wastes will be fundamentally analogous to those displaying cellulose. These substances have added-value by far surpassing raw material’s acquisition cost. When the main hydrothermal conversion products’ O/C, H/C molar ratios as reported in literature are plotted, an evolutionary trajectory for conversion products appears to be closely or even overlapped with fossil fuels’ geological evolution.

  14. Forest biomass variation in Southernmost Brazil: the impact of Araucaria trees / Variación de la biomasa forestal en el sur de Brasil: impacto de los árboles de Araucaria

    Scientific Electronic Library Online (English)

    Milena Fermina, Rosenfield; Alexandre F., Souza.

    2014-03-01

    Full Text Available SciELO Costa Rica | Language: English Abstract in spanish Una variedad de factores ambientales y bióticos determinan el crecimiento de la vegetación y afectan la acumulación de biomasa vegetal. Desde la temperatura hasta la composición de especies, en los ecosistemas forestales el almacenamiento de la biomasa aérea se ve influenciada por una serie de varia [...] bles, razón por la cual generalmente presenta una alta variabilidad espacial. De acuerdo a esto, el objetivo del estudio es analizar las variables que afectan la biomasa área (en Inglés, aboveground forest biomass - AGB) en los bosques húmedos subtropicales del sur de Brasil y analizar su distribución espacial. Para el estudio se utilizaron los datos de un inventario forestal realizado en el estado de Rio Grande del Sur, sur de Brasil. Se evaluaron bosques de hoja ancha (Broadleaf forests) y bosques mixtos de hoja ancha y coníferas (Mixed Coniferous-Broadleaf forests). Además, se tomaron muestras de 38 parcelas de 1 ha y para la estimación de la biomasa se incluyeron todos los árboles con DAP ?9.5cm. Los valores para la biomasa aérea se obtuvieron con ecuaciones alométricas publicadas. Las variables ambientales y bióticas (altitud, precipitación, temperatura, suelo, densidad de los troncos y diversidad de especies) se obtuvieron de la literatura o se han calculado a partir del conjunto de datos. Para el conjunto de datos, el AGB medio fue 195.2Mg/ha. Las estimaciones difieren entre los bosques de hoja ancha y los bosques mixtos de hoja ancha y coníferas: el AGB promedio fue menor en los bosques de hoja ancha (AGB BF=118.9Mg/ha) en comparación con los bosques mixtos (AGB MF=250.3Mg/ha). Hubo una alta variabilidad espacial y local en la base de datos, incluso dentro de los tipos de bosques. Esta condición es normal en los bosques tropicales y por lo general se atribuye a la presencia de grandes árboles. La regresión múltiple fue influenciada principalmente por la altitud y explicó 50.7% de la variación en AGB. La densidad, diversidad y materia orgánica también influyeron en la variación de biomasa. Los resultados mostraron una relación positiva entre la biomasa sobre el suelo y la altitud. Por lo tanto, los valores más altos de AGB se encuentran en altitudes mayores y se someten a temperaturas más bajas y un clima más húmedo. Parece que hay una importante contribución de las coníferas Araucaria angustifolia en las parcelas de bosques mixto, ya que tienen una biomasa significativamente mayor que las especies de angiospermas. En Brasil, esta especie en peligro de extinción es parte de un bosque de gran diversidad (Bosque de Araucaria) y tiene el potencial de almacenamiento de la biomasa. Los resultados del presente estudio muestran la variabilidad espacial y local de la biomasa aérea en los bosques subtropicales, destacan la importancia de estos ecosistemas en el almacenamiento global del carbono, y estimulan la mejora de futuras estimaciones de biomasa. Abstract in english A variety of environmental and biotic factors determine vegetation growth and affect plant biomass accumulation. From temperature to species composition, aboveground biomass storage in forest ecosystems is influenced by a number of variables and usually presents a high spatial variability. With this [...] focus, the aim of the study was to evaluate the variables affecting live aboveground forest biomass (AGB) in Subtropical Moist Forests of Southern Brazil, and to analyze the spatial distribution of biomass estimates. Data from a forest inventory performed in the State of Rio Grande do Sul, Southern Brazil, was used in the present study. Thirty-eight 1-ha plots were sampled and all trees with DBH ?9.5cm were included for biomass estimation. Values for aboveground biomass were obtained using published allometric equations. Environmental and biotic variables (elevation, rainfall, temperature, soils, stem density and species diversity) were obtained from the literature or calculated from the dataset. For the total dataset, mean AGB was 195

  15. Equation for estimating tree biomass in tropical forests of Costa Rica Ecuación para estimar la biomasa arbórea en los bosques tropicales de Costa Rica

    Directory of Open Access Journals (Sweden)

    Shu Wei-Chou

    2013-06-01

    Full Text Available One of the most relevant measures for climate change mitigation is the conservation and regeneration of forests in our countries. The amount of stored carbon in the forest biomass becomes a relevant variable for public policy. The present article analyses the association of some dasometric variables, easily obtained, with tree biomass with the purpose of indirectly estimating it, given that direct measurement of tree biomass is a complex and very expensive task. The general objective of this study was to analyze the pattern shown by dasometric variables, easily obtained, with tree biomass to estimate it by using data from two tropical forests in Costa Rica, with the purpose of analyzing its potential general application in tropical forests in the entire country. The bibliographic review helped to identify four possible models which estimate biomass in tropical forests. 907 trees were used with diameter at breast height (dbh greater than 10 cm in two tropical forests in Costa Rica (Corcovado National Park at the SW of the country, and Fila Carbón at the SE part, Caribbean slope, generating a biomass estimate as precise as possible. Dasometric variables (wood density, total height and dbh were used to analyze their relationship with biomass with the objective of finding a model that could predict it. The final model uses, as independent variables, dbh and density. Dbh has a high correlation with tree total height, which is very difficult to obtain in the field, therefore it was not used. The variable density is very important as it varies between trees having the same structure but of different species. To estimate the model, a segmented regression technique was used as well as weighted mean squares to solve for heteroscedasticity. The final model met all statistical assumptions for a linear model according to the residual and parametric analysis. The determination coefficient resulted in 0,992. As a conclusion, the study proposes a methodological approach to estimate forest biomass, which is very useful to support decision-making on carbon storage in tropical forests. Biomass determination in the field in future plots is going to help the calibration of this approach to estimate biomass stored in tropical forests.Una de las medidas más relevantes para la mitigación del cambio climático es la conservación y regeneración del bosque en nuestros países.  La cantidad de carbono que se almacena en la biomasa arbórea pasa a ser una medida relevante para la política pública. El presente trabajo analiza la asociación que tienen algunas variables dasométricas, fácilmente medibles, asociadas a la biomasa, con el propósito de estimarla indirectamente, dado que la medición directa de la biomasa arbórea es un trabajo complejo y tiene un costo muy elevado.  El objetivo general del estudio fue hacer un análisis del comportamiento de las variables dasométricas fácilmente medibles para predecir biomasa arbórea con datos de dos bosques tropicales de Costa Rica, con el propósito de analizar su posible aplicación generalizada en los bosques tropicales de todo el país. Mediante una revisión bibliográfica, se determinaron cuatro posibles modelos que estiman biomasa en bosques tropicales. Se evaluaron 907 árboles con diámetro a la altura de pecho (dap mayor a 10 cm en dos bosques tropicales de Costa Rica (Parque Nacional Corcovado en el suroeste y Fila Carbón en el sureste, vertiente del Caribe, generando una estimación de biomasa lo más precisa posible. Se realizó un análisis de las variables de los árboles (densidad específica de la madera, altura total y dap y su biomasa, con el fin de desarrollar el modelo que facilitara la predicción de esta. El modelo final utiliza como variables independientes el dap y la densidad.  Con el dap se da el hecho de que existe una alta correlación con la altura total, la cual es muy difícil de obtener en el campo, de modo que se decidió no utilizarla. La variable densidad es importante, ya que dos árboles con la misma estructura pero distinta densid

  16. The Effect of Habitual Smoking on VO2max

    Science.gov (United States)

    Wier, Larry T.; Suminski, Richard R.; Poston, Walker S.; Randles, Anthony M.; Arenare, Brian; Jackson, Andrew S.

    2008-01-01

    VO2max is associated with many factors, including age, gender, physical activity, and body composition. It is popularly believed that habitual smoking lowers aerobic fitness. PURPOSE: to determine the effect of habitual smoking on VO2max after controlling for age, gender, activity and BMI. METHODS: 2374 men and 375 women employed at the NASA/Johnson Space Center were measured for VO2max by indirect calorimetry (RER>=1.1), activity by the 11 point (0-10) NASA Physical Activity Status Scale (PASS), BMI and smoking pack-yrs (packs day*y of smoking). Age was recorded in years and gender was coded as M=1, W=0. Pack.y was made a categorical variable consisting of four levels as follows: Never Smoked (0), Light (1-10), Regular (11-20), Heavy (>20). Group differences were verified by ANOVA. A General Linear Models (GLM) was used to develop two models to examine the relationship of smoking behavior on VO2max. GLM #1(without smoking) determined the combined effects of age, gender, PASS and BMI on VO2max. GLM #2 (with smoking) determined the added effects of smoking (pack.y groupings) on VO2max after controlling for age, gender, PASS and BMI. Constant errors (CE) were calculated to compare the accuracy of the two models for estimating the VO2max of the smoking subgroups. RESULTS: ANOVA affirmed the mean VO2max of each pack.y grouping decreased significantly (p<0.01) as the level of smoking exposure increased. GLM #1 showed that age, gender, PASS and BMI were independently related with VO2max (R2 = 0.642, SEE = 4.90, p<0.001). The added pack.y variables in GLM #2 were statistically significant (R2 change = 0.7%, p<0.01). Post hoc analysis showed that compared to Never Smoked, the effects on VO2max from Light and Regular smoking habits were -0.83 and -0.85 ml.kg- 1.min-1 respectively (p<0.05). The effect of Heavy smoking on VO2max was -2.56 ml.kg- 1.min-1 (p<0.001). The CE s of each smoking group in GLM #2 was smaller than the CE s of the smoking group counterparts in GLM #1. CONCLUSIONS: After accounting for the effects of gender, age, PASS and BMI the effect of habitual smoking on reducing VO2max is minimal, about 0.85 ml/kg/min, until the habit exceeds 20 pack.y at which point an additional decrease of 1.71 ml/kg/min is noted. Adding pack.y data improves the accuracy of predicting the VO2max of smokers.

  17. Comparison of VO2 Peak and Achievement of VO2 Peak Criteria in Three Modes of Exercise in Female Triathletes.

    Science.gov (United States)

    Snoza, Colleen; Berg, Kris E; Slivka, Dustin

    2014-09-25

    The purpose of this study was to compare peak aerobic capacity in female triathletes in three modes of exercise: treadmill, cycle and arm ergometer. A second purpose was to determine the extent that physiologic criteria for achieving VO2 peak were reached in each mode of exercise. Six criteria were examined: VO2 plateau, heart rate (HR), blood lactate concentration (BLC), respiratory exchange ratio (RER), oxygen saturation, and rating of perceived exertion (RPE). Twelve recreational level female triathletes completed maximal tests on the treadmill, stationary bike, and arm ergometer. Results indicated VO2 peak (ml·kg·min) is highest on a treadmill (46.8±2.1), intermediate in cycling (40.7±5.0), and lowest in arm ergometry (28.2±3.3) with mean differences being significant (P < 0.05). BLC and RPE criteria were met by the highest number of subjects across the three modes of testing while the HR criterion was not achieved in any participant in arm ergometry and only 2 in cycling. It was concluded that in moderately trained recreational level triathletes, VO2 peak is highest in running and lowest in arm ergometry. Criteria for achieving VO2 peak most frequently were blood lactate level and RPE. Coaches and researchers should appreciate that VO2 peak values of moderately trained triathletes differ considerably in contrast to elite triathletes and tend to be highest on the treadmill and lowest in arm ergometry. Also, criteria used to determine achievement of VO2 peak should be carefully selected and appear to be best achieved using BLC and RPE. PMID:25259471

  18. High-contrast optical storage in VO2 films

    International Nuclear Information System (INIS)

    When vanadium dioxide, VO2, undergoes its semiconductor-to-metal transition at 68 degreeC its reflectivity decreases by about a factor of 2 throughout the visible range. By using a thin VO2 film on a vanadium substrate we were able to achieve a much higher contrast between the reflectivities of the two VO2 phases. The VO2 film was grown as an antireflecting coating for one of the phases and thus the film thickness was used to determine the light wavelength at which the contrast will reach its maximum value. For example, with an 800-A-thick film a contrast of 16 (rather than 2) was obtained at a light wavelength of 7000 A. In utilizing the present system for optical storage the high contrast obtained yielded an order of magnitude higher read-out efficiency than the efficiency reported for VO2 films sputtered on glass. To demonstrate information recording in the present system, both a pulsed laser and a cw laser were used for spatially selective''writing'' in the film. It was found that the present system has high ''write sensitivity'' with a threshold, easy erasability, and high-resolution capability. Cyclic operation without fatique and the convenience of using the same cw laser for both writing and reading, are other advantages of the system described

  19. Efeito de diferentes misturas de substratos orgânicos na biomassa e no óleo essencial de Thymus zygis Effect of different mixtures of organic substrates on the biomass and essential oil of Thymus zygis

    Directory of Open Access Journals (Sweden)

    Nelson Lourenço

    2011-07-01

    Full Text Available Neste ensaio avaliou-se o efeito de diferentes misturas de substrato comercial e vermicomposto na produção de biomassa, composição química e rendimento dos óleos essenciais de Thymus zygis. Utilizaram-se 5 substratos resultantes da mistura de um vermicomposto (V com um substrato orgânico comercial (O, em cinco proporções diferentes (v/v: V100 (100%V; VO75-25 (75%V+25%O; VO50 -50 (50%V+50%O; VO 25-75 (25%V + 75%O e O100 (100%O. A inclusão do vermicomposto no substrato não melhorou a produção de biomassa. Na modalidade O100 produziu-se mais biomassa, tendo sido na modalidade VO25-75 onde se obteve o valor mais baixo. Na modalidade V100 todas as plantas secaram tendo-se ainda apresentado nesta modalidade o valor mais elevado de pH e de densidade real e inversamente o menor valor de espaço poroso total. Os monoterpenos oxigenados predominaram nos óleos extraídos das plantas nas modalidades O100 e VO25-75, contrariamente ao que se verificou para os monoterpenos não oxigenados tendo estes predominado nas modalidades VO75-25 e VO50-50. A concentração de timol foi elevada nas misturas testadas, em particular na modalidade VO25-75.In this trial we evaluated the effect of different mixtures of organic growing media substratum and vermicompost and their physical properties on biomass, chemical composition and yield of essential oils of Thymus zygis. Five treatments were established based on two types of organic materials (O, commercial growing media, and V, vermicompost. The following proportions were studied (v/v: V100 (100%V; VO75-25 (75%V+25%O; VO50-50 (50%V+50%O; VO 25-75 (25%V+75%O and O100 (100%O. The inclusion of vermicompost did not improve biomass production. The treatment O100 produced more biomass and the lowest was obtained in VO25-75. On V100 treatment all plants were dead and also have showed the highest pH and particle density and conversely presented the lowest value of total pore space. Oxygenated monoterpenes predominated in the oils extracted from plants in O100 and VO25-75, contrary to what was found for non-oxygenated monoterpenes having these prevailed in VO75-25 and VO50-50. The concentration of thymol was high in the mixtures tested, particularly in VO25-75.

  20. A VO-driven Astronomical Data Grid in China

    CERN Document Server

    Cui, Chenzhou; Yang, Yang; Zhao, Yongheng

    2010-01-01

    With the implementation of many ambitious observation projects, including LAMOST, FAST, and Antarctic observatory at Doom A, observational astronomy in China is stepping into a brand new era with emerging data avalanche. In the era of e-Science, both these ambitious projects and traditional astronomy research need much powerful data management, sharing and interoperability. Based on data-grid concept, taking advantages of IVOA interoperability technologies, China-VO is developing a VO-driven astronomical data grid environment to enable multi-wavelength science and large database science. In the paper, latest progress and data flow of the LAMOST, architecture of the data grid, and its supports to the VO are discussed.

  1. Crecimiento y distribución de biomasa en girasol en función del nitrógeno y densidad de población en clima cálido

    Directory of Open Access Journals (Sweden)

    V\\u00EDctor Manuel Olalde Guti\\u00E9rrez

    2000-01-01

    Full Text Available En condiciones de clima cálido subhúmedo (Aw0 se estableció un experimento en Cocula, Guerrero, durante el temporal de 1998, con el objetivo de evaluar el efecto de la aplicación, antes de la siembra, de tres niveles de nitrógeno (0, 10 y 20 g m-2 y tres densidades de población (5, 7.5 y 10 pl m-2, sobre el número de hojas verdes por m2, índice de área foliar y distribución de materia seca en los órganos de la planta de girasol (Helianthus annuus L.. El diseño experimental fue bloques al azar con arreglo en parcelas divididas y cuatro repeticiones. En general se observaron incrementos en el número de hojas e índice del área foliar con la aplicación de nitrógeno y el aumento en densidad de población. La distribución de materia seca en los órganos de la planta durante el ciclo del cultivo y a la cosecha también se afectó positivamente con estos tratamientos. Durante el desarrollo del cultivo, la mayor acumulación de biomasa ocurrió en el tallo, seguido del capítulo, semilla y hoja. A la cosecha, la mayor proporción de materia seca se asignó en forma decreciente en tallo, semilla, receptáculo y hoja. Por otra parte, el nitrógeno incrementó la materia seca de las semillas en el capítulo, pero ésta se redujo al aumentar la densidad de población. Bajo estas condiciones ambientales, con la combinación de 10 g de N m-2 (100 kg de N ha-1 y 10 pl m-2 (100 mil plantas por hectárea, se produjo el mayor ingreso neto.

  2. MODELOS DE REGRESIÓN PARA ESTIMAR ÁREA DE LA HOJA Y BIOMASA DE ÓRGANOS EN ÁRBOLES JÓVENES DE MANZANO

    Directory of Open Access Journals (Sweden)

    A. Curiel-Rodr\\u00EDguez

    2007-01-01

    Full Text Available Se generaron modelos matemáticos empíricos de aplicación general con técnicas de regresión lineal múltiple, para estimar el área de la hoja y la biomasa aérea en manzano "Agua Nueva II" / M-7, útiles en estudios de crecimiento, relaciones fuente-demanda y productividad. Los modelos obtenidos tienen alta precisión, (R2 > 0.969. El área (AFE, el peso seco de la lámina de la hoja (PSL y el peso seco de pecíolo (PSP pueden ser estimados con los modelos: AFE= -3.24140(AL + 0.67616(AL2 + 1.63287(AL (LL/AL; PSL= 0.02699(AFE + 0.00021917(AFE2; y PSP= 0.00384(AFE - 0.04432 (LL/AL + 0.02291(LL/AL, respectivamente, donde AL y LL son ancho máximo y largo de la lámina de la hoja, respectivamente. Se mide la longitud, el diámetro proximal o basal y el diámetro distal o apical de cada rama, tallo y tronco. Estas medidas se utilizan para calcular el volumen en fresco (V de cada uno de esos órganos como un cono truncado. El volumen se utilizó para los modelos: PST= 0.6688(V, PSTP= 0.55902(V, lnPSRG= 0.77462[ln(V], PSRM= 0.49349(V y PSRP= 0.57297(V; éstos estiman los pesos secos del tronco (PST, del tallo principal (PSTP, de ramas grandes (PSRG, medianas (PSRM y pequeñas o dardos (PSRP de cada planta. EL modelo del peso seco para el sistema radical (PSRZ está en función de la longitud (LPT y diámetro distal del tronco: PSRZ= 10.80747(LPT(DDT + (-01.37171 (DDT2. Las longitudes y los diámetros se expresan en centímetros, el área en centímetros cuadrados, el volumen en centímetros cúbicos y los pesos en gramos.

  3. Biomasa, rendimiento, eficiencia en el uso del agua y de la radiación solar del agrosistema girasol-frijol

    Directory of Open Access Journals (Sweden)

    Edgar J. Morales-Rosales

    2006-01-01

    Full Text Available El estudio se realizó durante el verano de 2002 Los tratamientos consistieron en la siembra en unicultivo y combinación de frijol Canario 107, Bayomex (hábito de crecimiento determinado, Michoacán (hábito de crecimiento indeterminado y girasol cv. Victoria. La siembra se realizó el 25 de mayo de 2002 a la densidad de población de 4.2 y 8.3 plantas m-2 de girasol y frijol, respectivamente, en un suelo de textura arcillosa, con un pH de 7.8 y se fertilizó con 100-100-00 de NPK. El diseño experimental fue bloques al azar con cuatro repeticiones. El sistema de siembra no afectó la fenología, el requerimiento térmico y la evapotranspiración de ambos cultivos. Las unidades calor (UC y la evapotranspiración (ETc de los cultivos de la siembra a la madurez fisiológica fueron 1521 UC y 279.6 mm para el cv. Victoria, 658 UC y 201.3 mm para Canario 107, 811 UC y 213.7 mm para Bayomex y 1041 UC y 241.7 mm para Michoacán. El agrosistema combinado de girasol y frijol fue más eficiente en el uso de los insumos para la producción agrícola. La combinación de girasol Victoria y frijol Michoacán mostró la eficiencia en el uso del agua (EUA y eficiencia en el uso de la radiación (EUR más alta y, en consecuencia, una mayor producción de biomasa y rendimiento. El uso equivalente de la tierra (UET para el rendimiento de semilla obtenido con la combinación de Victoria más Canario 107, Victoria más Michoacán y Victoria más Bayomex fue de 1.6, 1.9 y 3.0, respectivamente, y muestra una ventaja en el rendimiento de los cultivos combinados sobre los unicultivos de 60, 90 y 200%, respectivamente.

  4. PRELIMINARY ANALYSIS OF BIOMASS POTENTIALLY USEFUL FOR PRODUCING BIODIESEL / ANALISIS PRELIMINAR DE BIOMASA POTENCIALMENTE ÚTIL PARA PRODUCIR BIODIESEL

    Scientific Electronic Library Online (English)

    GERARDO, CABRERA CIFUENTES; JUAN CARLOS, BURBANO JARAMILLO; JOSÉ ISIDRO, GARCIA MELO.

    2011-12-01

    Full Text Available Considerando que el biodiesel se está convirtiendo en una solución viable para algunos problemas energéticos y medioambientales, la investigación de materias primas para su producción es un tema de creciente interés. Este estudio presenta los resultados de una investigación dedicada al análisis prel [...] iminar de varias especies vegetales (biomasa), potencialmente útiles para producir biodiesel. La zona de bioprospección es una región de la costa pacifica colombiana. Las especies promisorias recolectadas fueron sometidas a diferentes pruebas normalizadas ASTM para definir propiedades que faciliten su evaluación. Algunas de las especies fueron sometidas a un proceso de transesterificación. Adicionalmente, se realiza una comparación entre las propiedades termo-físicas de los biodiesel y las propiedades del diesel comercial. Las pruebas de rendimiento de estos biocombustibles en los motores de encendido por compresión, particularmente la eficiencia, el consumo y la potencia a diferentes RPM del motor, se presentan en este trabajo. Abstract in english Given that biodiesel is emerging as a viable solution for some energy and environmental problems, research on raw materials appropriate for its production is a matter of growing interest. In this study we present the results of research devoted to preliminary analysis on several vegetable (biomass) [...] species potentially useful for producing biodiesel. The bioprospection zone is a region on the Colombian Pacific coast. The candidate species collected underwent different standardized ASTM tests in order for us to define properties that facilitate their evaluation. Some of the species underwent a transesterification process. Comparisons between the thermo-physical properties of the biofuels obtained and the properties of commercial diesel were carried out. Also, performance tests for these biofuels were conducted in compression ignition engines, particularly evaluating efficiency, fuel consumption, and potency at different RPMs.

  5. Influence of Prior Exercise on VO2 Kinetics Subsequent Exhaustive Rowing Performance

    OpenAIRE

    Sousa, Ana; Ribeiro, Joa?o; Sousa, Marisa; Vilas-boas, Joa?o Paulo; Fernandes, Ricardo J.

    2014-01-01

    Prior exercise has the potential to enhance subsequent performance by accelerating the oxygen uptake (VO2) kinetics. The present study investigated the effects of two different intensities of prior exercise on pulmonary VO2 kinetics and exercise time during subsequent exhaustive rowing exercise. It was hypothesized that in prior heavy, but not prior moderate exercise condition, overall VO2 kinetics would be faster and the VO2 primary amplitude would be higher, leading to longer exercise time ...

  6. VoIP Client for Multi-core Server Enhancing Quality of Real Time Service Delivery

    OpenAIRE

    Bereka Shewara, Jemil

    2012-01-01

    Voice over Internet Protocol (VoIP) is a fast growing service in communication technology. Due to the cost-effectiveness, many organizations have been deploying VoIP technology for their teleconferencing and video conferencing services. In recent decades, various types of client and server applications have been developed, and different application protocols have been standardized. However, most of VoIP applications were developed for single core architecture. The increasing demand of VoIP se...

  7. Biomasa de rotíferos de dos embalses con diferentes estados tróficos (Antioquia, Colombia) y su relación con algunas variables limnológicas / Rotifer biomass of two reservoirs with different trophic states (Antioquia, Colombia) and its relationship with some limnological variables

    Scientific Electronic Library Online (English)

    Silvia L, Villabona-González; Robinson F, Buitrago-Amariles; John J, Ramírez-Restrepo; Jaime A, Palacio-Baena.

    2014-12-01

    Full Text Available Se evaluó la variación de la biomasa de rotíferos en los ejes longitudinal y vertical de la zona fótica de los embalses La Fe y Riogrande II (Antioquia), Colombia, con diferentes estados tróficos, durante los periodos de alta y baja precipitación. Además, se analizó su relación con las variables tem [...] peratura, oxígeno disuelto, pH, transparencia, nutrientes y con la biomasa fitoplanctónica. La biomasa de rotíferos fue dominada por Asplanchna girodi De Geurne 1888, en los dos embalses y fue significativamente mayor en el embalse de menor trofía. Aunque la biomasa de rotíferos no mostró un gradiente longitudinal significativo, sí presentó zonación vertical dentro de la zona fótica, con mayor biomasa en el 10 y 1% de incidencia lumínica. Los patrones de variación de la biomasa total de rotíferos y de las especies dominantes estuvieron determinados principalmente por el ingreso de sólidos suspendidos en el embalse de mayor trofía y por la biomasa y la densidad del fitoplancton en el embalse con menos nutrientes. A diferencia de lo esperado, la biomasa de los rotíferos no fue favorecida por condiciones de mayor estado trófico, ya que el factor preponderante sobre la expresión de biomasa fue la calidad de los recursos alimenticios en cada embalse. Abstract in english Rotifers biomass was evaluated across longitudinal and vertical axes of the photic zone in the La Fe y Riogrande II reservoirs (Antioquia), Colombia, with different trophic states during periods of high and low precipitation. IN addition, its relationship with temperature, dissolved oxygen, pH, tran [...] sparency, nutrient availability, and phytoplankton biomass was analyzed. In both reservoirs, rotifer biomass was dominated by Asplanchna girodi De Geurne, 1888, and it was significantly higher in the reservoir with a lower trophic state. Even though rotifers biomass did not exhibit a longitudinal gradient, a vertical zonation in the photic zone was documented, with the greatest biomass at 10% and 1% of light intensity. Patterns of variation in total rotifer biomass and in dominant species biomass appear to be determined primarily by the entry of suspended solids into the reservoir with the higher trophic state, and by phytoplankton biomass and density in the reservoir with lower nutrient levels. Contrary to expectations, rotifer biomass was not favored by increasing trophic state. The most important factor determining rotifer biomass was the quality of food resources in each reservoir.

  8. Modelos de biomasa aérea y foliar en una plantación de pino de rápido crecimiento en Oaxaca / Above-ground and needle biomass models on a fast-growing pine plantation in Oaxaca

    Scientific Electronic Library Online (English)

    Gerardo, Rodríguez-Ortiz; Héctor M., De Los Santos-Posadas; Víctor A., González-Hernández; Arnulfo, Aldrete; Armando, Gómez-Guerrero; Aurelio M., Fierros-González.

    Full Text Available El vigor de un árbol se puede evaluar a partir del follaje, que si bien representa de 4% a 6% de la biomasa total del árbol, es el componente principal para los procesos fisiológicos. El objetivo de este estudio fue estimar la biomasa de acículas en ramas individuales y árbol completo, y ajustar mod [...] elos de partición de biomasa aérea en árboles plantados de Pinus patula Schl. et Cham. La biomasa de acículas por rama se estimó con un modelo lineal, que empleó área basal de rama viva, altura de rama y el seccionamiento de copa como variables independientes. La biomasa de los componentes aéreos se estimó con coeficientes de determinación de 0,86; 0,92 y 0,88; para madera con corteza, ramas y acículas, respectivamente. Para madera con corteza se utilizó el diámetro normal (DN) y altura de árbol (AT) en un modelo lineal; la biomasa de ramas y follaje con ecuaciones no lineales que se basaron en el diámetro de copa viva (DCV) y área de copa para ramas; y DCV y AT para la biomasa de follaje. La biomasa total aérea por árbol se estimó con un R² = 0,87; utilizando DN y AT. La biomasa a una edad de 14 años se distribuyó en 92,9%; 4,7% y 2,4% para madera, ramas y follaje, respectivamente. Abstract in english A forest tree health can be accurately assessed by evaluating foliage biomass; even when it represents only 4% to 6% of the total tree biomass, it is the main driver of every major physiological processes. This research was mainly focused on estimating accurately needle biomass at branch and tree le [...] vel on fast growing trees of Pinus patula Schl. et Cham. Needle biomass per branch was estimated with a linear model, which used live branch basal area, live branch height, and crown section like independent variables. Above ground components were estimated with determination coefficients of 0,86, 0,92 and 0,88 for wood with bark, branches and needles. For the wood with bark model, diameter at breast height (DBH) and total tree height (HT) were used in a linear structure; total branch biomass was fitted with a non-linear model, using live crown diameter (LCD) and crown area (CA) while total needle biomass used LCD and HT on a non-linear model. The aboveground total biomass per tree was estimated with R² = 0.87, using DBH and HT. At 14 years old, biomass partition was estimated to be 92,9%, 4,7% and 2,4% for wood with bark, branches and needles, respectively.

  9. Estimación de biomasa y carbono en dos especies arboreas en La Sierra Nevada, México / Estimation of biomass and carbon in two arboreal species in the Sierra Nevada, Mexico

    Scientific Electronic Library Online (English)

    Fernando, Carrillo Anzúres; Miguel, Acosta Mireles; Eulogio, Flores Ayala; Juana Eliud, Juárez Bravo; Eunice, Bonilla Padilla.

    2014-08-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Se generaron dos ecuaciones para determinar biomasa y carbono en Pinus montezumae y Alnus jorullensis H. B. K. ssp. jorullensis especies de importancia ecológica de los bosques de la Sierra Nevada en el Estado de México. Las ecuaciones que se determinaron son de la forma Y= bXk, donde Y es el conten [...] ido de biomasa o de carbono (kg) y X el diámetro normal (DN) en cm. Para estimar los valores b y k del modelo para cada especie, se utilizaron 15 árboles de Pinus montezumae y 16 de Alnus jorullensis ssp. jorullensis. En Pinus montezumae el mayor porcentaje de biomasa 77.07 % se estimó en el fuste incluido el tocón, mientras que en las ramas y el follaje presentó 8.45 y 9.01%, respectivamente, con la biomasa y el DN de los árboles se obtuvo el ajuste de los parámetros b y k del modelo propuesto (B= 0.013 DN3.0462) con una R²= 0.9909. Para el caso de Alnus jorullensis ssp. jorullensis de la misma forma el mayor porcentaje de biomasa 63.77% se estimó en el fuste incluido el tocón, mientras que en las ramas y el follaje presentó 20.99 y 11.46%, respectivamente; con la biomasa y el DN de los árboles se obtuvo el ajuste de los parámetros b y k del modelo propuesto (B= 0.0195 DN2.7519) con una R²= 0.9311. Después de analizar el contenido de carbono en las muestra de cada especie, se ajustaron las ecuaciones para Pinus montezumae C= 0.0065DN3.0484, con una R²= 0.9914, mientras que para Alnus jorullensis ssp. jorullensis C= 0.009DN2.7522con una R²= 0.9313. Abstract in english Two equations were generated for determining the biomass and carbon in Pinus montezumae and Alnus jorullensis HBK ssp. jorullensis of ecological important species of the forests of the Sierra Nevada in the State of Mexico. The equations were determined are of the form Y= bXk, where Y is the biomass [...] content or carbon (kg) and X normal diameter (DN) in cm. For estimating the model and k values for each species, Pinus montezumae 15 trees and 16 Alnus jorullensis ssp. jorullensis were used. In Pinus montezumae the highest percentage of biomass was estimated at 77.07% including the stem stump, while the branches and foliage showed 8.45 and 9.01%, respectively, biomass and DN trees the adjustment is obtained by k parameters of the proposed model (B= 0.013 DN3.0462) with R²= 0.9909. For the case of Alnus jorullensis ssp. jorullensis the same as the highest percentage of biomass was estimated at 63.77% including the stem stump, while the branches and foliage showed 20.99 and 11.46%, respectively; with biomass and tree DN setting the parameters of the proposed model by k (B= 0.0195 DN2.7519) with R²= 0.9311 was obtained. After analyzing the carbon content in the sample of each species, the equations for Pinus montezumae C= 0.0065DN3.0484, with R²= 0.9914, while for Alnus jorullensis ssp jorullensis was adjusted. C= 0.009DN2.7522 con an R²= 0.9313.

  10. Estimación de biomasa aérea en plantaciones de Cedrela odorata L. y Swietenia macrophylla King / Aerial biomass estimation in Cedrela odorata L. and Swietenia macrophylla King plantations

    Scientific Electronic Library Online (English)

    Agustín, Rueda Sánchez; Agustín, Gallegos Rodríguez; Diego, González Eguiarte; J. Ariel, Ruiz Corral; Juan de Dios, Benavides Solorio; Eduardo, López Alcocer; Miguel, Acosta Mireles.

    2014-10-01

    Full Text Available Se evaluaron las capacidades de producción de biomasa y de captura de carbono en plantaciones de Cedrela odorata y Swietenia macrophylla con 12 años en el estado de Jalisco. En campo fueron seleccionados y derribados 15 árboles de cada especie para determinar la biomasa y el carbono en el estrato aé [...] reo; se tomaron muestras del fuste, de las ramas (brazuelo y leña) y del follaje de cada individuo para conocer su peso fresco; en el laboratorio se secaron para obtener el peso seco y con estos datos se calculó la biomasa total de cada ejemplar a partir de la relación peso seco: peso fresco. Para realizar las estimaciones se ajustaron ecuaciones de regresión tipo polinomial y potencial, el diámetro normal y la altura fueron las variables independientes. Al peso seco de cada componente del árbol se le aplicó un índice de captura de carbono de 0.4269 y con ello se obtuvo el potencial de captura de carbono atmosférico. Para C. odorata el total de biomasa promedio por espécimen fue de 34 kg, en la que se distribuye 75 % de la biomasa en el fuste, 11 % en el brazuelo, 9 % en ramas (leña) y 5 % en el follaje. Para S. macrophylla el total de biomasa promedio por espécimen fue de 26 kg, del cual 47 % se distribuye en el fuste, 19 % en el brazuelo, 23 % en ramas y 10 % en el follaje. Abstract in english This study was conducted with the aim of assessing the ability of biomass production and carbon sequestration by plantations of Cedrela odorata and Swietenia macrophylla in a plantation established 12 years ago in the state of Jalisco, Mexico. At Costa de Jalisco Experimental Site of the Instituto N [...] acional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP) and 15 trees of each species were selected and felled and the biomass and carbon in the aerial stratum were determined. Samples were taken from the stem, branches (twigs and firewood) and foliage of each of the selected trees and fresh weight was determined in the field from both species; the samples were dried in a laboratory to obtain the dry weight and estimate the total biomass of each tree using the ratio dry weight: fresh weight of samples. To estimate the biomass and carbon and polynomial regression equations were fit; the independent variables were normal diameter and tree height. To the dry weight of each tree component was applied a carbon sequestration index of 0.4269, thereby determining the potential for atmospheric carbon sequestration. For C. odorata, the total average biomass per tree was 34 kg, 75 % of which belongs to the biomass in the stem, 11 % in the trunk, 9 % in branches (wood) and 5 % in foliage. For S. macrophylla, the total average biomass per tree was 26 kg, which are distributed as 47 % in the stem, 19 % in the trunk, 23 % in branches and 10 % in the foliage.

  11. Individual plant and population biomass of dominant shrubs in Patagonian grazed fields / Biomasa individual y poblacional de arbustos dominantes en estepas patagónicas pastoreadas

    Scientific Electronic Library Online (English)

    Gastón R, Oñatibia; Martín R, Aguiar; Pablo A, Cipriotti; Fernando, Troiano.

    2010-12-01

    Full Text Available SciELO Argentina | Language: English Abstract in spanish La estimación de la biomasa aérea de la vegetación es clave para llevar a cabo estudios de Ecología de Poblaciones, de Comunidades y de Ecosistemas. En sistemas dominados o codominados por leñosas, esta estimación es dificultosa, y es importante contar con métodos rápidos y no destructivos. En este [...] estudio describimos cómo se distribuye la biomasa aérea en distintos componentes (i.e., leño, hojas) y cómo cambia con el tamaño de arbusto para las tres especies dominantes de arbustos del Distrito Occidental de la estepa Patagónica. Además, describimos la estructura poblacional de tamaños de las tres especies en campos pastoreados y estimamos su contribución a la abundancia y la biomasa total a través de un método no destructivo. Desarrollamos ecuaciones alométricas para estimar la biomasa de los componentes aéreos de los individuos de arbustos a partir de descriptores estructurales (i.e., diámetros y altura de la copa). La variable que mejor predijo la biomasa aérea en las tres especies de arbustos fue la suma de la altura y el diámetro promedio (entre el diámetro mayor y el perpendicular) de la copa. Los modelos alométricos explicaron para cada especie más de 83% de la variabilidad de la biomasa aérea individual. En el nivel de individuo, las especies tuvieron distinta proporción de leño, hojas y distinto peso específico del leño. El aumento del tamaño individual de los arbustos fue acompañado por cambios en las proporciones de hojas/leño y en algunos casos por el porcentaje de copa muerta. En el nivel de población, las tres especies difirieron en la distribución de tamaños en pastizales pastoreados. La perspectiva poblacional utilizada para el desarrollo de los modelos alométricos es clave para estudiar los procesos demográficos que explican las respuestas de las comunidades y los ecosistemas áridos a los principales cambios ambientales y de uso. Abstract in english Estimating aboveground biomass of vegetation is essential for population, community and ecosystem studies. In systems dominated or co-dominated by woody species, biomass estimation is difficult, and rapid and non-destructive methods are needed. In this study, we describe biomass distribution in diff [...] erent components (i.e., wood, leaves) and how this changes with shrub size for the three dominant species of shrubs in the Occidental District of the Patagonian steppe. We also describe the population size structure of the three species in grazed fields and estimate their contribution to total abundance and biomass through a non-destructive method. We developed allometric equations to estimate aboveground biomass components of individual shrubs from structural descriptors (i.e., diameter and height of the crown), sampling individual plants of different sizes. The variable that best predicted biomass of the three species was the sum of the height and the average diameter of the crown (calculated with the largest diameter and its perpendicular). Allometric models for each species explained more than 83% of the variability of individual aboveground biomass. At the individual level, species had different proportions of wood, leaves and specific wood weight. Increasing shrub size was accompanied by changes in the proportion of leaves to wood, and in some cases, the percentage of dead crown. At the population level, the three species differed in size distribution in moderately grazed fields. Development of allometric models from a population perspective is important to study demographic processes that drive community and ecosystem responses to environmental and land-use changes.

  12. Carbono almacenado en la biomasa aérea de plantaciones de araucaria (Araucaria angustifolia -Bert.- O. Ktze) / Aboveground carbon stocks in plantations of araucariaç (Araucaria angustifolia -Bert.- O. Ktze)

    Scientific Electronic Library Online (English)

    José D, Vega; Rodolfo, Martiarena.

    2010-06-01

    Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish En este trabajo se estima el carbono aéreo almacenado en plantaciones de Araucaria angustifolia (Bert.) O. Ktze de diferentes edades, localizadas en el norte de la provincia de Misiones. Se determina la biomasa aérea por muestreo destructivo de árboles de 1, 2, 3, 6, 20, 30 y 40 años de edad, se aju [...] stan ecuaciones para estimar el peso seco de los restantes árboles de la parcela y se calcula la biomasa y el carbono en la totalidad de la plantación de cada una de las edades. El carbono almacenado en la biomasa aérea es de 0,04; 0,31; 1,3; 21,9; 56,2; 60,5 y 92,2 Mg.ha-1 para las edades de 1, 2, 3, 6, 20, 30 y 40 años respectivamente. Abstract in english This work estimated the aboveground carbon stock in plantations of Araucaria angustifolia -Bert.- O. Ktze of different ages, located in the north of the province of Misiones. The aboveground biomass was determined by destructive sampling of trees of 1, 2, 3, 6, 20, 30 and 40 years of age, equations [...] were adjusted to estimate the dry weight of the remaining trees of the plot and biomass and carbon were calculated in the whole plantation of exemplars of all the ages mentioned. The carbon of the total aboveground biomass is 0,04; 0,31; 1,3; 21,9; 56,2; 60,5 and 92,2 Mg.ha-1 for tree ages 1, 2, 3, 6, 20, 30 and 40, respectively.

  13. Producción de biomasa de Artemia franciscana Kellogg 1906 utilizando diferentes dietas / Biomass production of Artemia franciscana Kellogg 1906 using different diets

    Scientific Electronic Library Online (English)

    Rosario, Cisneros; Enrique, Vinatea.

    2009-12-01

    Full Text Available Se realizó el cultivo semiintensivo de Artemia franciscana, cepa Perú, utilizando diferentes dietas en base a microalgas e insumos alimenticios que forman parte de algunos ingredientes que se utilizan para preparar alimento formulado de peces y crustáceos, con el fin de determinar la factibilidad de [...] l uso de estos para la obtención de biomasa de adultos. El estudio se ejecutó en base a un diseño experimental completamente aleatorio con 7 tratamientos y 3 réplicas cada uno, aplicándose a los datos obtenidos un Análisis de Varianza de una vía (ANOVA) y la prueba de Tukey para establecer diferencias significativas entre los tratamientos. Los resultados del análisis próximal de las dietas, mostraron que la harina de soya presentó la cantidad de proteínas requerida por A. franciscana durante su crecimiento (34.33 %), igualmente con esta dieta se obtuvo la mejor tasa de crecimiento (0.19), biomasa más alta (113.33 g) y el mejor Factor de Conversión Alimenticia (1.4). Así mismo la biomasa de A. franciscana producida con harina de soya, presentó un nivel de proteínas adecuado para la maduración de reproductores de crustáceos (53.38 %). Abstract in english Artemia franciscana, Peru strain, was cultured under different diets-based in microalgae and nutritious inputs with the aim to determine the feasibility to produce adult Artemia biomass. A completely randomized design experiment was carried out, with seven treatments and three replications each one. [...] One way variance analysis (ANOVA) and the Turkey test were used to analyze the data to establish significant differences among treatments. The results of biochemical analysis showed that soya bean diet fulfilled the protein content needed for a proper growth of A. fransiscana. This diet also showed the best growth rate (0.19), highest biomass production (113.13 g), best food conversion ratio (1.4) and a protein content suited for crustacean broodstock maturation (53.38%).

  14. Pressure-induced transformations in PrVO4 and SmVO4 and isolation of high-pressure metastable phases.

    Science.gov (United States)

    Errandonea, Daniel; Achary, S Nagabhusan; Pellicer-Porres, Julio; Tyagi, Avesh K

    2013-05-01

    Zircon-type PrVO4 and SmVO4 have been studied by high-pressure Raman spectroscopy up to 17 GPa. The occurrence of phase transitions has been detected when compression exceeds 6 GPa. The transformations are not reversible. Raman spectra of the high-pressure phases show similarities with those expected for a monazite-type phase in PrVO4 and a scheelite-type phase in SmVO4.The high-pressure phases have been also synthesized using a large-volume press and recovered at ambient conditions. X-ray diffraction measurements of the metastable products recovered after decompression confirms the monazite (PrVO4) and scheelite (SmVO4) structures of the high-pressure phases. Based upon optical properties of the reported new polymorphs, novel applications for rare-earth vanadates are proposed, including photocatalytic hydrogen production. PMID:23600563

  15. Producción de biomasa de la microalga Scenedesmus sp. utilizando aguas residuales de pescadería / Biomass production of microalga Scenedesmus sp. with wastewater from fishery

    Scientific Electronic Library Online (English)

    Charity E, Andrade R; Alexandra L, Vera B; Carmen H, Cárdenas L; Ever D, Morales A.

    2009-08-01

    Full Text Available Las microalgas representan una alternativa para el tratamiento de aguas residuales por su capacidad de remoción de nutrientes y alto valor comercial de la biomasa producida. Se evaluó el crecimiento, remoción de nutrientes y materia orgánica de la microalga Scenedesmus sp. en aguas residuales deriva [...] das de restos de pescadería. Se utilizaron cultivos discontinuos en tanques a cielo abierto con 150L, aireación constante y en condiciones no controladas de fotoperiodo y temperatura. Se evaluó el crecimiento de la microalga mediante recuento celular, peso seco y contenido de pigmentos, realizando la recolección de la misma en fase estacionaria mediante sedimentación natural, y efectuando análisis fisicoquímicos a la biomasa secada al sol. La microalga creció en agua residual a cielo abierto, reportando eficiencias de remoción de 94,44% (23,80mg/L) para nitrógeno amoniacal, de 77,54% (7,04mg/L) para fosfatos y de 35,59% (26,09mg/L) para materia orgánica. La biomasa seca resultó ser un componente de alto contenido proteico (24,41%), fibroso (10,04%), con niveles de grasa (2,47%) y minerales (23,52%) adecuados para complementar la nutrición animal. Estos resultados demostraron que Scenedesmus puede ser utilizada para el tratamiento de aguas residuales con la producción de una biomasa de valor agregado. Abstract in english The microalgae represent an alternative for the treatment of wastewater for his capacity of removal of nutrients and high commercial value of produced biomass. There was evaluated the growth, removal of nutrients and organic matter of Microalgae Scenedesmus sp. in wastewater derived from remains of [...] fish. Discontinuous cultures were in use in tanks to sky opened with 150L, constant aeration and in conditions no controlled of photoperiod and temperature. The growth of microalgae we evaluated by means of cell counting, dry weight and content of pigments, realizing the compilation of the same one in stationary phase by means of natural sedimentation, and effecting physicochemical analyses to the biomass dried to the sun. The microalgae grew in wastewater to opened sky, reporting efficiencies of removal of 94.44% (23.80 mg/L) for ammonia nitrogen, 77.54% (7.04 mg/L) for phosphates and 35.59 % (26.09 mg/L) for organic matter. The dry biomass recollected was a component of high contained protein (24,41%), fibrous (10,04%), with levels of fats (2,47%) and mineral (23,52%) adapted to complement the animal nutrition. These results showed that Scenedesmus can be used for the treatment of wastewater by production of a biomass of added value.

  16. Validade de equações de predição em estimar o VO2max de brasileiros jovens a partir do desempenho em corrida de 1.600m / Predictive equations validity in estimating the VO2max of young Brazilians from performance in a 1600 m run

    Scientific Electronic Library Online (English)

    Jeeser Alves de, Almeida; Carmen S. G., Campbell; Emerson, Pardono; Rafael da Costa, Sotero; Guilherme, Magalhães; Herbert Gustavo, Simões.

    2010-02-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste estudo foi analisar a validade da equação proposta por Cureton et al. (1995) "VO2peak = -8.41 (MRW) + 0.34 (MRW)2 + 0.21 (Age x Gender) -0.84 (BMI) + 108.94" em estimar o VO2max de brasileiros jovens a partir de um teste de 1.600 metros, e sugerir uma equação de predição que seja es [...] pecífica para essa população. Participaram do estudo 30 homens fisicamente ativos (23 ± 3,1anos; 74,8 ± 5,8kg; 1,78 ± 0,05m; 49,8 ± 6,5mL.kg-¹.min-1) que foram submetidos a um teste incremental máximo (TI) em esteira e um teste de desempenho em corrida de 1.600 metros. Os indivíduos foram divididos em dois grupos: G1 - para gerar uma equação de predição específica para VO2max de brasileiros jovens e G2 - para aplicar ambas as equações a fim de analisar suas validades. Diferenças estatisticamente significativas foram observadas entre o VO2max determinado diretamente no TI (50,1 ± 7,1mL.kg-¹.min-¹) e os valores de VO2max obtidos pela equação proposta por Cureton et al. (44,2 ± 6,5mL.kg-¹.min-¹) com baixa correlação entre elas (r = 0,21). A relação entre VO2max e velocidade em corrida de 1.600m obtidos no G1 resultou na seguinte equação de predição: (VO2max = 0,177 * 1.600Vm(m.min-1) + 8,101). Quando essa nova equação foi aplicada nos participantes do G2, o VO2max predito (50,1 ± 7,2mL.kg-¹.min-¹) não diferiu do VO2max determinado diretamente (50,1 ± 7,1mL.kg-¹.min-¹) com alta correlação entre eles (r = 0,81). Assim, concluímos que a equação de Cureton et al. (1995), elaborada a partir de resultados de amostra norte-americana, subestimou o VO2max de brasileiros jovens e fisicamente ativos. Por outro lado, a equação proposta no presente estudo se mostrou válida para estimar o VO2max através do teste de desempenho de 1.600 metros para a população estudada. Abstract in english The aim of the present study was to analyze the validity of predictive equation proposed by Cureton et al. (1995) for VO2peak = -8.41 (MRW) + 0.34 (MRW) 2 + 0.21 (Age x Gender) -0.84 (BMI) + 108.94" on estimating the VO2max of young Brazilians from a 1600-m running performance, and to suggest a pred [...] ictive equation specific for this population. 30 physically active young men (23±3.1age; 74.8±5.8kg; 1.78±0.05m; 49.8±6.5mL.kg-¹.min-1) who were submitted to an incremental exercise test (IT) on treadmill until exhaustion with gas analysis participated in this study. Subjects also performed a 1600-m running track test as fast as possible. The volunteers were randomly sorted in two groups: G1 - to generate a specific predictive equation for VO2max, and G2 - to apply both predictive equations (actual and from Cureton et al.) to evaluate their validity on estimating VO2max in a Brazilian population sample. Significant differences were observed between VO2max directly identified on IT through gas analysis (50.1±7.1 mL.kg-¹.min-¹) in relation to the results obtained by the predictive equation proposed by Cureton et al. (1995) (44.2±6.5mL.kg-¹.min-¹) with a weak relationship between them (r = 0.21). The relationship between the VO2max on IT and the running velocity on 1600-m as obtained for G1 resulted in the following predictive equation: (VO2max = 0.177*1600Vm(m.min-1) + 8,101). When this new equation was applied on the participants of G2, the predicted VO2max (50.1±7.2mL.kg-¹.min-¹) did not differ from VO2max determined directly on IT (50.1±7.1mL.kg-¹.min-¹) with a high correlation between them (r = 0.81). Thus, it was concluded that the Cureton et al. predictive equation developed with a North Americanpopulation sample as grounding, underestimated the VO2max of physically active young Brazilians. On the other hand, the predictive equation proposed on the present study was considered valid for this purpose through the 1600-m running performance for our participants.

  17. Synthesis and characterization of FeVO4 nanoparticles

    International Nuclear Information System (INIS)

    Highlights: ? Simple co-precipitation method were employed for the synthesis of FeVO4. ? The calcination temperature and the reaction time were optimized. ? The effect of surfactants on the structural, morphological and magnetic properties was studied. ? The shape of the particles changes due to the effect of surfactant. ? Enhancement of magnetic orderings on the addition of surfactant. -- Abstract: Iron vanadate (FeVO4) nanoparticles were synthesized by simple co-precipitation method using various surfactants such as ethylene glycol, polyethylene glycol 200 and polyethylene glycol 400 as the structure directing agents. Systematic investigations on the structural, morphological and magnetic properties of the materials have been studied. The lattice constants of the triclinic structure of FeVO4 were calculated from the X-ray diffraction (XRD) analyses. The average grain size was estimated to be around 35 nm, which increased with increasing the calcination temperature. The stretching and bending vibrations of Fe-O were evaluated from the FT-IR spectra. Using VSM magnetometer, magnetic property was investigated through magnetic susceptibility and magnetization measurements. FeVO4 exhibits two magnetic ordering temperatures at T ? 20 K and 14 K, which is due to two different chemical environments of Fe ligands such as octahedral FeO6 and trigonal bipyramidal FeO5 in a six-column doubly bent chain, respectively.

  18. Improving Quality of VoIP over WiMAX

    Directory of Open Access Journals (Sweden)

    M.A. Mohamed

    2012-05-01

    Full Text Available Real-time services such as VoIP are becoming popular and are major revenue earners for network service providers. These services are no longer confined to the wired domain and are being extended over wireless networks. Although some of the existing wireless technologies can support some low-bandwidth applications, the bandwidth demands of many multimedia applications exceed the capacity of these technologies. The IEEE 802.16-based WiMAX promises to be one of the wireless access technologies capable of supporting very high bandwidth applications. In this paper, we exploit the rich set of flexible features offered at the medium access control (MAC layer of WiMAX for the construction and transmission of MAC protocol data units (MPDUs for supporting multiple VoIP streams. We discuss the quality of VoIP calls, usually given by R-score, with respect to the delay and loss of packets. We analysis the quality of service (QoS on long distance data transfer between two locations with VoIP over WiMAX will be performed. Performance of selected parameters will be done using the network simulator, OPNET Modeler 14.5 [1,2].

  19. Transport and Magnetic Properties of MgFeVO4

    Science.gov (United States)

    Zhang, Xue; Kuang, Xiao-Jun; Wang, Yong-Gang; Wang, Xiao-Ming; Wang, Chun-Hai; Zhang, Yan; Chen, Chinping; Jing, Xi-Ping

    2013-02-01

    A new spinel compound, MgFeVO4, was prepared by solid-state reactions. On the basis of the Mössbauer spectrum, it can be deduced that both Fe and V in MgFeVO4 are trivalent. Structure refinements based on X-ray and neutron diffraction data indicated that V3+ ions are likely to occupy the octahedral site, whereas Fe3+ and Mg2+ ions take both octahedral and tetrahedral sites. The formula of the compound can be represented as (Mg1-xFex)[MgxFe1-xV]O4 (x=0.638). The transport measurements indicate that MgFeVO4 is an n-type semiconductor with the hopping mechanism below 170 K and thermally activated mechanism at high temperatures. The DC and AC magnetic data show the antiferromagnetic interactions and spin glass behavior in MgFeVO4. The time-dependent magnetic relaxation and the exchange bias effect related to the spin glass phase are also analyzed. The curve fittings give long flipping times and large n values, indicating that strongly interacting clusters rather than individual spins are the predominant spin glass features.

  20. Synthesis and characterization of FeVO{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nithya, V.D. [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Selvan, R. Kalai, E-mail: selvankram@buc.edu.in [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Sanjeeviraja, C. [School of Physics, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Radheep, D. Mohan; Arumugam, S. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India)

    2011-10-15

    Highlights: {yields} Simple co-precipitation method were employed for the synthesis of FeVO{sub 4}. {yields} The calcination temperature and the reaction time were optimized. {yields} The effect of surfactants on the structural, morphological and magnetic properties was studied. {yields} The shape of the particles changes due to the effect of surfactant. {yields} Enhancement of magnetic orderings on the addition of surfactant. -- Abstract: Iron vanadate (FeVO{sub 4}) nanoparticles were synthesized by simple co-precipitation method using various surfactants such as ethylene glycol, polyethylene glycol 200 and polyethylene glycol 400 as the structure directing agents. Systematic investigations on the structural, morphological and magnetic properties of the materials have been studied. The lattice constants of the triclinic structure of FeVO{sub 4} were calculated from the X-ray diffraction (XRD) analyses. The average grain size was estimated to be around 35 nm, which increased with increasing the calcination temperature. The stretching and bending vibrations of Fe-O were evaluated from the FT-IR spectra. Using VSM magnetometer, magnetic property was investigated through magnetic susceptibility and magnetization measurements. FeVO{sub 4} exhibits two magnetic ordering temperatures at T {approx} 20 K and 14 K, which is due to two different chemical environments of Fe ligands such as octahedral FeO{sub 6} and trigonal bipyramidal FeO{sub 5} in a six-column doubly bent chain, respectively.

  1. "Kogda emotsii vo mne bezuderzhno põlajut..." : [luuletused] / Jevgenia Brodneva

    Index Scriptorium Estoniae

    Brodneva, Jevgenia

    2003-01-01

    Sisu: "Kogda emotsii vo mne bezuderzhno põlajut..." ; "Võ menja nikogda ne vstretite..." ; "Kogda nastupit vremja rasstavanja..." ; "Prosti za lozh i za obidu..." ; "Ja v plenu svoihh sobstvennõhh tshuvstv..." ; "Ot nego nelzja otkazatsja..." ; "Mne b rukoi do tebja dotjanutsja..." ; "Ja potshti, ja potshti v tebja vljublena..." ; "Ja po tebe skutshaju..."

  2. Structure and magnetism of epitaxial PrVO3 films

    International Nuclear Information System (INIS)

    The interplay between charge, spin, orbital and lattice degrees of freedom in transition metal oxides has motivated extensive research aiming to understand the coupling phenomena in these multifunctional materials. Among them, rare earth vanadates are Mott insulators characterized by spin and orbital orderings strongly influenced by lattice distortions. Using epitaxial strain as a means to tailor the unit cell deformation, we report here on the first thin films of PrVO3 grown on (001)-oriented SrTiO3 substrate by pulsed laser deposition. An extensive structural characterization of the PrVO3 films, combining x-ray diffraction and high-resolution transmission electron microscopy studies, reveals the presence of oriented domains and a unit cell deformation tailored by the growth conditions. We have also investigated the physical properties of the PrVO3 films. We show that, while PrVO3 exhibits an insulating character, magnetic measurements indicate low-temperature hard-ferromagnetic behavior below 80 K. We discuss these properties in view of the thin-film structure. (fast track communication)

  3. Kraftkonstanten des VO43- -Ions im Zirkon-Gitter [1] / Force Constants of the VO43- Ion in the Zircon Lattice

    Science.gov (United States)

    Escobar, Marta E.; Baran, Enrique J.

    1980-10-01

    Force Constants of the VO43- Ion in the different rare earth orthovanadates of the zircon type have been computed using a modified valence force field and recently reported Raman data. It is shown that the V-O bond strenghtening runs parallel to the unit cell contraction. The Raman spectrum of the tetragonal modification of LaVO4 is reported for the first time.

  4. Structural and thermal studies on Pu(VO3)4

    International Nuclear Information System (INIS)

    An hitherto unknown metavanadate of plutonium with composition Pu(VO3)4 was synthesized by heating appropriate amounts of pre-dried PuO2 and V2O5 at 640 deg C for 48 h. The brownish product obtained was characterized by Rietveld refinement of powder XRD data and thermogravimetric analysis. Structural analyses revealed that, Pu(VO3)4 crystallizes in tetragonal (space group: I41/a) lattice with unit cell parameters: a = 8.4582(3) and c = 28.683(2) and Z = 8. The crystal structure of Pu(VO3)4 is isostructural to Th(VO3)4 and Np(VO3)4. TG curve of Pu(VO3)4 did not show any weight change up to 1000 deg C. DTA peaks at 665 and 575 deg C correspond to the melting and crystallization of Pu(VO3)4. (author)

  5. Un modelo simple para describir la dinámica de la biomasa del camarón nailon Heterocarpus reedi en Coquimbo, Chile / A simple model for describing the biomass dynamics of the nylon shrimp Heterocarpus reedi at Coquimbo, Chile

    Scientific Electronic Library Online (English)

    Eduardo P., Pérez.

    2005-11-01

    Full Text Available RESUMEN. Entre septiembre de 1997 y agosto de 2000 se realizó un seguimiento diario de la dinámica espacial y temporal de la CPUE (ton·lance-1) de camarón nailon por parte de la flota arrastrera con puerto base en Coquimbo. Se construyó un modelo de remoción de biomasa modificado para explicar las v [...] ariaciones temporales de la CPUE basado en los conceptos de abundancia (biomasa total poblacional) y disponibilidad (biomasa que puede ser potencialmente capturada). Ambas cantidades fueron calculadas por ecuaciones, cuyas diferencias (positivas o negativas) indicaron los cambios en la disponibilidad de la biomasa a través del tiempo y el reclutamiento (magnitud y temporalidad). El modelo modificado indicó dos períodos anuales de distinta longitud en la disponibilidad de biomasa al arte de pesca. También indicó una tasa de reducción más acelerada para la biomasa que para la CPUE. Los resultados pueden influir en la determinación de la época óptima para la realización de las evaluaciones directas del recurso con fines de determinar cuotas de captura Abstract in english A daily record of space/time dynamics was carried out on CPUE (ton·trawl-1) for the nylon shrimp trawl fishery based at Coquimbo, Chile, between September 1997 and August 2000. A modified biomass depletion model was constructed to analyze the temporal variations in CPUE based on the concepts of abun [...] dance (total population biomass) and availability (potential biomass capture). Both quantities were calculated by equations whose differences (positive and negative) indicated the changes in availability of biomass over time, as well as recruitmernt (magnitude and seasonality). The modified model suggested there were two periods annually, of different lengths, and different biomasses available with the fishing gear. The model also indicated a more rapid rate of reduction in biomass than did the CPUE. The results could influence the determination of the best season for carrying out direct resource evaluations aimed at determining catch quotas

  6. The ROI of VoIP: Everybody Says VoIP Saves Big Bucks. But Does It?

    Science.gov (United States)

    Villano, Matt

    2006-01-01

    Advocates of Voice over Internet Protocol (VoIP) say it saves money on long distance calls by sending them over the Internet, improves communication by eliminating the Private Branch Exchange (PBX), and offers a host of neat features such as call forwarding, e-mail accessible voicemail, and more. When it comes to measuring the dollars-and-cents…

  7. E-LEARNING SOLUTIONS IN EDUCATION OF PEDAGOGIC EMPLOYEES / E-learningové riešenia vo vzdelávaní pedagogických zamestnancov

    Directory of Open Access Journals (Sweden)

    Jakubeková Miroslava

    2008-06-01

    Full Text Available According to the requirements on qualitative forms and methods of education, Methodical-pedagogical centre, has prepared a project supporting teaching with use of modern educaton methods with sponzorship from ESF For providing such an extensive project the Methodical-pedagogical centre used e-learning environment. The first part of article emphasizes the importance of teachers education in the new socio-economical conditions. It defines the needs of teachers in the field of using ICT during the education process. It describes forms and methods suitable for gaining new competencies. The second part of the article gives us the information abouth e-learning portal of the project „Functional literacy of teachers in information technologies - use of ICT in subjects". The modules are using the different possibilities of MOODLE interface. Author evaluates the interest of teachers for e-learning and the feedback from lectu-trers. The third part of the article presents first experience of using videoconference in the field of education of teachers, on example of a conference aimed to use of ICT in the work of elementary and high school teachers (in the preparation for teaching and also in the teaching process itself.Na základe potreby zvyšovania k?ú?ových kompetencií pedagogických zamestnancov bol s finan?nou podporou ESF pripravený projekt na podporu vyu?ovania s využitím moderných vyu?ovacích metód. Na zabezpe?enie rozsiahleho projektu v oblasti využívania informa?ných technológií a na zvýšenie efektívnosti vzdelávania pedagogických zamestnancov využilo Metodicko-pedagogické centrum v Tren?íne e-learningové prostredie. Príspevok v prvej ?asti poukazuje na význam vzdel?vania u?ite?ov v nových spolo?ensko-eko-nomických podmienkach. Definuje potreby u?ite?ov v oblasti využívania IKT na vyu?ovaní a predstavuje formy a metódy vhodné na získanie nových kompetencií. V druhej ?asti príspevku je predstavený e-learningový portál projektu Funk?ná gramotnos? u?ite?ov v informa?ných technológiách - využitie IKT vo vyu?ovacích predmetoch. Jednotlivé vzdelávacie moduly rozli?nou mierou využívajú možnosti prostredia MOODLE. Autor vyhodnocuje záujem pedagógov o e-learningové vzdelávanie a skúsenosti lektorov zo vzdelávania. V tretej ?asti príspevku sú predstavené prvé skúsenosti využitia videokonferencie v oblasti vzdelávania pedagógov na príklade konferencie zameranej na využívanie informa?ných technológií v práci pedagógov z?kladných a stredných škôl - v príprave na vyu?ovanie i vo vlastnom vyu?ovacom procese.

  8. Relação entre a variabilidade da frequência cardíaca e VO 2pico em mulheres ativas / Relationship between heart rate variability and VO 2peak in active women / Relación entre la variabilidad de la frecuencia cardíaca y VO 2pico en mujeres activas

    Scientific Electronic Library Online (English)

    Nayara Yamada, Tamburús; Ana Cristina Silva, Rebelo; Marcelo de Castro, César; Aparecida Maria, Catai; Anielle Cristhine de Medeiros, Takahashi; Carolina Pieroni, Andrade; Alberto, Porta; Ester da, Silva.

    2014-10-01

    Full Text Available OBJETIVO: Ava+liar a associação entre os índices da variabilidade da frequência cardíaca (VFC) e a aptidão cardiorrespiratória. MÉTODOS: Sessenta e duas mulheres (idade 22,1 ± 3,3 anos) foram divididas em quatro grupos: treinamento aeróbio (AER, n = 15), treinamento de força (FOR, n = 13), tre [...] inamento combinado (aeróbio e força) (AER+FOR, n = 15) e controle (C, n = 19). O teste cardiopulmonar foi realizado para avaliar a aptidão cardiorrespiratória a partir do consumo de oxigênio pico (VO2pico). A FC foi coletada em repouso na postura supina. A VFC foi analisada a partir de métodos lineares e não lineares. RESULTADOS: Os grupos AER e AER+FOR apresentaram maiores índices da VFC (lineares e não lineares) indicadores da modulação vagal e menores índices da VFC indicadores da modulação simpática, em relação ao grupo C. Os grupos AER e AER+FOR apresentaram maior complexidade e menor regularidade dos intervalos RR e maior VO2pico em relação aos grupos FOR e C. O VO2pico apresentou correlação com os índices da VFC. CONCLUSÃO: Este estudo mostrou que o treinamento físico aeróbio e combinado contribuíram significativamente para maior modulação autônoma da FC e aptidão cardiorrespiratória. A modulação autônoma da FC, avaliada a partir de métodos lineares e não lineares, está associada ao maior consumo de oxigênio. Abstract in spanish OBJETIVO: Evaluar la asociación entre los índices de variabilidad de la frecuencia cardíaca (VFC) y la aptitud cardiorrespiratoria. MÉTODOS: Sesenta y dos mujeres (edad 22,1 ± 3,3 años) fueron divididas en cuatro grupos: entrenamiento aeróbico (AER, n = 15), entrenamiento de fuerza (FOR, n = 1 [...] 3), entrenamiento combinado (aeróbico y fuerza) (AER+FOR, n = 15) y control (C, n = 19). El test cardiopulmonar fue realizado para evaluar la aptitud cardiorrespiratoria a partir del consumo de oxígeno pico (VO2pico). La FC fue colectada en reposo en la postura supina. La VFC fue analizada a partir de métodos lineales y no lineales. RESULTADOS: Los grupos AER y AER+FOR presentaron mayores índices de VFC (lineales y no lineales) indicadores de la modulación vagal y menores índices de VFC indicadores de la modulación simpática, en relación al grupo C. Los grupos AER y AER+FOR presentaron mayor complejidad y menor regularidad de los intervalos RR y mayor VO2pico en relación a los grupos FOR y C. O VO2pico presentó correlación con los índices de VFC. CONCLUSIÓN: Este estudio mostró que el entrenamiento físico aeróbico y combinado contribuyeron significativamente para mayor modulación autónoma de FC y aptitud cardiorrespiratoria. La modulación autónoma de FC, evaluada a partir de métodos lineales y no lineales, está asociada al mayor consumo de oxígeno. Abstract in english OBJECTIVE: To evaluate the associations between heart rate variability (HRV) with cardiorespiratory fitness. METHODS: Sixty-two women (aged 22.1 ± 3.3) were divided into four groups: aerobic training (AER, n = 15), strength training (STR, n = 13), combined aerobic and strength training (AER+ST [...] R, n = 15) and controls (C, n = 19). Cardiopulmonary exercise testing was performed to measure cardiorespiratory fitness by assessing peak oxygen consumption (VO2peak). The HR was recorded at rest in the supine position. The HRV was analyzed by linear and nonlinear methods. RESULTS: The AER and AER+STR groups had higher vagal HRV (linear and nonlinear) indicators of vagal modulation and lower indices of HRV indicators of sympathetic modulation, compared to group C. The AER and AER+STR groups showed greater complexity and lower regularity of R-R intervals and higher peak compared to STR and C groups. The VO2peak was correlated with HRV indices. CONCLUSION: This study showed that aerobic and combined exercise significantly contributed to greater autonomic modulation of HR and cardiorespiratory fitness. The autonomic HR modulation, assessed by linear and nonlinear methods, was associated with a greater oxygen consumption.

  9. Aqueous citrato-oxovanadate(IV) precursor solutions for VO2: synthesis, spectroscopic investigation and thermal analysis.

    Science.gov (United States)

    Peys, Nick; Adriaensens, Peter; Van Doorslaer, Sabine; Gielis, Sven; Peeters, Ellen; De Dobbelaere, Christopher; De Gendt, Stefan; Hardy, An; Van Bael, Marlies K

    2014-09-01

    An aqueous precursor solution, containing citrato-VO(2+) complexes, is synthesized for the formation of monoclinic VO2. With regard to the decomposition of the VO(2+) complexes towards vanadium oxide formation, it is important to gain insights into the chemical structure and transformations of the precursor during synthesis and thermal treatment. Hence, the conversion of the cyclic [V4O12](4-) ion to the VO(2+) ion in aqueous solution, using oxalic acid as an acidifier and a reducing agent, is studied by (51)Vanadium nuclear magnetic resonance spectroscopy. The citrate complexation of this VO(2+) ion and the differentiation between a solution containing citrato-oxalato-VO(2+) and citrato-VO(2+) complexes are studied by electron paramagnetic resonance and Fourier transform infra-red spectroscopy. In both solutions, the VO(2+) containing complex is mononuclear and has a distorted octahedral geometry with a fourfold R-CO2(-) ligation at the equatorial positions and likely a fifth R-CO2(-) ligation at the axial position. Small differences in the thermal decomposition pathway between the gel containing citrato-oxalato-VO(2+) complexes and the oxalate-free gel containing citrato-VO(2+) complexes are observed between 150 and 200 °C in air and are assigned to the presence of (NH4)2C2O4 in the citrato-oxalato-VO(2+) solution. Both precursor solutions are successfully used for the formation of crystalline vanadium oxide nanostructures on SiO2, after thermal annealing at 500 °C in a 0.1% O2 atmosphere. However, the citrato-oxalato-VO(2+) and the oxalate-free citrato-VO(2+) solution result in the formation of monoclinic V6O13 and monoclinic VO2, respectively. PMID:25005054

  10. Efecto del estrés hídrico simulado y la inoculación con esporas de Glomus mosseae sobre el crecimiento y la partición de biomasa en avena

    Directory of Open Access Journals (Sweden)

    M. F. Ruscitti

    2007-01-01

    Full Text Available El estrés hídrico limita el rendimiento de las plantas. La micorriza favorece el crecimiento y confiere resistencia a la sequía. El objetivo de este trabajo fue estudiar el efecto del estrés hídrico moderado sobre la micorrización, el crecimiento y la partición de biomasa en plantas de avena (Avena sativa L. inoculadas con esporas de Glomus mosseae, a diferentes profundidades. Se sembró avena en sustrato estéril sin esporas y con 100 esporas a 4, 8 ó 12 cm de profundidad. La mitad de las plantas se sometieron a estrés moderado. Se determinó: área foliar, peso seco de parte aérea y raíz, porcentaje de colonización y dependencia micorrícica. Después de 60 días de la siembra, el porcentaje de colonización en las plantas regadas e inoculadas a 4 y 8 cm de profundidad y en las estresadas, a 4 cm de profundidad, fue de 25%, mientras que en el resto de los tratamientos fue significativamente menor. La biomasa seca aérea y de raíz fue significativamente mayor en las plantas estresadas inoculadas, a 8 y a 12 cm de profundidad, comparadas con las del tratamiento testigo. La arquitectura de las raíces estresadas se modificó con la inoculación: mostraron una menor longitud y un aumento significativo de las raíces laterales. Las plantas estresadas presentaron mayor dependencia micorrícica, comparadas con las no estresadas. Según estos resultados, la inoculación con esporas de G. mosseae fue una estrategia favorable para soportar situaciones de estrés hídrico y la ubicación del inóculo fue un factor determinante en la respuesta de la planta.

  11. Evaluación agronómica y nutricional del pasto Ryegrass perenne tetraploide (Lolium perenne producido en lecherías de las zonas altas de Costa Rica. I. Producción de biomasa y fenología

    Directory of Open Access Journals (Sweden)

    Luis Villalobos

    2010-01-01

    3090 msnm, provincia de Cartago. La disponibilidad de materia seca pre y pos-pastoreo, el aprovechamiento por hectárea y su porcentaje de utilización promedio para todas las fincas fueron 4110, 2276 y 1833 kg.ha-1 por corte y 44,82%, respectivamente. La edad fenológica y la relación hoja: tallo promedio de las pasturas de ryegrass perenne fueron 2,84 hojas verdes por rebrote, 56:44. Asimismo, la composición promedio de la pradera fue 76,09% ryegrass, 13,76% otras gramíneas (principalmente pasto kikuyo, 6,02% trébol, 1,25% malezas y 2,88% material senescente, respectivamente. La mayor producción de biomasa durante marzo y abril puede conservarse para utilizarse durante las épocas críticas de disponibilidad de forraje o cuando por razones climatológicas se reduce el número de horas efectivas de pastoreo. La evaluación de la edad fenológica en que se pastorea el pasto ryegrass perenne, indica que las fincas en la zona de estudio utilizan esta gramínea en un estado en el que sus reservas de carbohidratos se han recuperado, lo que permite obtener una producción de biomasa y valor nutricional adecuados para satisfacer las necesidades del ganado lechero de la zona.

  12. Método basado en teledetección para estimar la emisión de gases efecto invernadero por quema de biomasa A remote sensing method to estimate greenhouse gas emissions from biomass burning

    Directory of Open Access Journals (Sweden)

    Jesús Adolfo Anaya Acevedo

    2011-01-01

    Full Text Available La quema de biomasa es una fuente importante de gases efecto invernadero en países en vías de desarrollo. En Colombia, el cambio de uso del suelo, la silvicultura y el sector agropecuario superan el 50% de las emisiones totales de efecto invernadero. El fuego se utiliza con frecuencia como un mecanismo para cambiar el uso del suelo. Los Llanos orientales y la Amazonía colombiana están sometidos todos los años a la quema de biomasa, especialmente entre enero y marzo. Los estudios en la distribución espacial y temporal de las emisiones son importantes de cara a los informes en el ámbito nacional. Este artículo de revisión describe el método para hacer estas estimaciones utilizando teledetección y algunos de los resultados disponibles para Colombia.Biomass burning is a major source of greenhouse gas emissions in developing countries. In Colombia, land use change, forestry and agriculture are responsible for more than 50% of the total greenhouse gas emissions. Fire is commonly used as a mechanism for land use change. In Colombia the Llanos Orientales and the Amazonia are subject to biomass burning every year during the dry season, especially from January to March. Studies of the spatial and temporal distribution of emissions are required for emissions report at a national level. The goal of this state of the art article is to describe a method to estimate emissions with a remote sensing approach and to present some of the variables already measured in Colombia.

  13. Influence of inoculum on growth and retention of the biomass in anaerobic filters / Influencia del inoculo sobre el crecimiento y la retención de biomasa en filtros anaerobios

    Scientific Electronic Library Online (English)

    Patricia, Torres-Lozada; Andrea, Pérez-Vidal.

    2014-09-01

    Full Text Available SciELO Colombia | Language: English Abstract in spanish En este estudio se evaluaron dos filtros anaerobios de igual configuración en escala de laboratorio y usando cáscara de coco como material de soporte, para el tratamiento de las aguas residuales del proceso de extracción de almidón de yuca. Considerando que en el área de estudio el inóculo disponibl [...] e en cantidad suficiente es el estiércol de vaca, se usó este inóculo solo (Reactor R1) y combinado con lodo granular en una proporción 1:1 (Reactor R2). Se evaluó la influencia del inóculo sobre el desempeño de los filtros anaerobios, sobre la adaptación de la biomasa al sustrato y sobre el crecimiento prevalente en el material de soporte. Ambos reactores mostraron potencial para el tratamiento de estas aguas residuales, con un Tiempo de Retención Hidráulico (TRH) de aproximadamente 12 horas, Carga Orgánica Volumétrica (COV) de 7.0 kg DQO/m3*d y un Índice Buffer (IB) entre 0.20 y 0.35. El incremento hasta de 50% en la Actividad Metanogénica Específica (AME) al final del arranque en ambos reactores, confirmó la adecuada adaptación de la biomasa al sustrato como resultado del control de la capacidad buffer; adicionalmente, los mayores valores de AME en el R2 mostraron que la mezcla de estiércol de vaca con lodo granular mejoró la producción de metano y la eficiencia del proceso. Se encontró que la biomasa ocluida tuvo mayor actividad que la biomasa adherida, indicando que el medio de soporte favoreció el desarrollo de una mayor proporción de biomasa activa en los intersticios del material de soporte. Abstract in english In this study we evaluated, on bench scale, two anaerobic filters of equal configuration and using coconut shell as support material, for the treatment of the wastewater generated in cassava's starch extraction process. Considering that in the study area the inoculum available in enough quantity is [...] cow manure, this inoculum was used alone (Reactor 1) and mixed with granular sludge in a ratio of 1:1 (Reactor 2). The influence of inoculum was evaluated in the performance of the anaerobic filters as well as in the biomass adaptation to the substrate and the prevalent growth on support material. Both reactors showed potential for the treatment of this type of wastewater, with a Hydraulic Retention Time (HRT) of 12 hours, an average Organic Loading Rate (OLR) of 7.0 kg COD/m3*d and a Buffer Index (BI) that varied from 0.20 to 0.35. The increase up to 50% in the Specific Methanogenic Activity (SMA) at the end of the start-up in both reactors, confirmed the adequate biomass adaptation to the substrate as a result of the control of buffer capacity, and the higher values in the R2, showed that cow manure mixed with granular sludge improved methane production and process efficiency. It was found that the occluded biomass had greater activity than the attached one; this showed that the support material allowed the development of a greater proportion of active biomass within the interstices.

  14. Determinants of time limit at velocity corresponding to VO2max in physically active individuals

    Directory of Open Access Journals (Sweden)

    Jefferson da Silva Novaes

    2008-01-01

    Full Text Available The objective of the present study was to determine the relationship between time limit (Tlim at VO2Máx velocity (VVO2Máx and the variables VO2Máx, VVO2Máx, running economy (RE, ventilatory threshold (VT, strength test (9-10 maximum repetitions, velocity at maximal anaerobic running test (VMART, vertical jump test and body fat percentage. The sample was composed of 18 male volunteers, aged between 18 and 45 years old, non-athletes, but physically active. The study was carried out during fi ve visits, on non-consecutive days and at approximately the same time each day: visit 1 - signature of informed consent form, medical history, anthropometric assessment, aerobic power test and familiarization with Tlim test; visit 2 - RE test and Tlim test; visit 3 - familiarization with VMART test; visit 4 - familiarization with vertical jump and 9-10 maximum repetition tests and VMART test; visit 5 - vertical jump and 9-10 maximum repetition tests. Low (r = 0.220 to – 0.359 and non-significant correlations (p = 0.281 to 0.935 were observed between Tlim and the selected variables, characterizing the low predictive value of Tlim for the sample studied. Thus, and because of the considerable inter-individual variability in Tlim, no variable was identified that was capable of satisfactorily predicting Tlim. Resumo O objetivo do presente estudo foi determinar a relação do tempo limite (Tlim na velocidade do VO2Máx (VVO2Máx com as variáveis VO2Máx, VVO2Máx, economia de corrida (EC, limiar ventilatório (LV, força isotônica (determinada pelo teste de 9-10 RM, velocidade no teste máximo de corrida anaeróbica (VMART, impulsão vertical e percentual de gordura (%G . A amostra foi composta por 18 voluntários do sexo masculino, com idade entre 18 e 45 anos, não atletas, regularmente ativos. O estudo foi realizado em cinco visitas, em dias não consecutivos e aproximadamente no mesmo horário, compostas de: visita 1 - assinatura do termo de consentimento, anamnese, avaliação antropométrica, teste de potência aeróbia e familiarização ao teste de Tlim; visita 2 - teste de EC e teste de Tlim; visita 3 - familiarização ao teste de VMART; visita 4 - familiarização aos testes de impulsão vertical e 9-10 RM e teste de VMART; visita 5 - testes de impulsão vertical e 9-10 RM. Foram observadas correlações baixas (r = 0,220 a - 0,359 e não significativas (p = 0,281 a 0,935 entre Tlim e as diversas variáveis selecionadas, o que caracteriza uma baixa qualidade preditiva para o TLim na amostra estudada. Neste sentido e tendo em vista a considerável variabilidade inter-indivíduos do TLim, não foi encontrada uma variável que pudesse predizê-lo satisfatoriamente.

  15. Progressive recruitment of muscle fibers is not necessary for the slow component of VO2 kinetics.

    Science.gov (United States)

    Zoladz, Jerzy A; Gladden, L Bruce; Hogan, Michael C; Nieckarz, Zenon; Grassi, Bruno

    2008-08-01

    The "slow component" of O2 uptake (VO2) kinetics during constant-load heavy-intensity exercise is traditionally thought to derive from a progressive recruitment of muscle fibers. In this study, which represents a reanalysis of data taken from a previous study by our group (Grassi B, Hogan MC, Greenhaff PL, Hamann JJ, Kelley KM, Aschenbach WG, Constantin-Teodosiu D, Gladden LB. J Physiol 538: 195-207, 2002) we evaluated the presence of a slow component-like response in the isolated dog gastrocnemius in situ (n=6) during 4 min of contractions at approximately 60-70% of peak VO2. In this preparation all muscle fibers are maximally activated by electrical stimulation from the beginning of the contraction period, and no progressive recruitment of fibers is possible. Muscle VO2 was calculated as blood flow multiplied by arteriovenous O2 content difference. The muscle fatigued (force decreased by approximately 20-25%) during contractions. Kinetics of adjustment were evaluated for 1) VO2, uncorrected for force development; 2) VO2 normalized for peak force; 3) VO2 normalized for force-time integral. A slow component-like response, described in only one muscle out of six when uncorrected VO2 was considered, was observed in all muscles when VO2/peak force and VO2/force-time were considered. The amplitude of the slow component-like response, expressed as a fraction of the total response, was higher for VO2/peak force (0.18+/-0.06, means+/-SE) and for VO2/force-time (0.22+/-0.05) compared with uncorrected VO2 (0.04+/-0.04). A progressive recruitment of muscle fibers may not be necessary for the development of the slow component of VO2 kinetics, which may be caused by the metabolic factors that induce muscle fatigue and, as a consequence, reduce the efficiency of muscle contractions. PMID:18483168

  16. Epitaxial growth of VO2 by periodic annealing

    International Nuclear Information System (INIS)

    We report the growth of ultrathin VO2 films on rutile TiO2 (001) substrates via reactive molecular-beam epitaxy. The films were formed by the cyclical deposition of amorphous vanadium and its subsequent oxidation and transformation to VO2 via solid-phase epitaxy. Significant metal-insulator transitions were observed in films as thin as 2.3?nm, where a resistance change ?R/R of 25 was measured. Low angle annular dark field scanning transmission electron microscopy was used in conjunction with electron energy loss spectroscopy to study the film/substrate interface and revealed the vanadium to be tetravalent and the titanium interdiffusion to be limited to 1.6?nm

  17. Epitaxial growth of VO{sub 2} by periodic annealing

    Energy Technology Data Exchange (ETDEWEB)

    Tashman, J. W.; Paik, H.; Merz, T. A. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Lee, J. H. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Moyer, J. A.; Schiffer, P. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Misra, R. [Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mundy, J. A. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Spila, T. [Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Schubert, J. [Peter Grünberg Institute, PGI 9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany); Muller, D. A. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States); Schlom, D. G., E-mail: schlom@cornell.edu [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

    2014-02-10

    We report the growth of ultrathin VO{sub 2} films on rutile TiO{sub 2} (001) substrates via reactive molecular-beam epitaxy. The films were formed by the cyclical deposition of amorphous vanadium and its subsequent oxidation and transformation to VO{sub 2} via solid-phase epitaxy. Significant metal-insulator transitions were observed in films as thin as 2.3?nm, where a resistance change ?R/R of 25 was measured. Low angle annular dark field scanning transmission electron microscopy was used in conjunction with electron energy loss spectroscopy to study the film/substrate interface and revealed the vanadium to be tetravalent and the titanium interdiffusion to be limited to 1.6?nm.

  18. Cooperative emission study in ytterbium doped NdVO4

    International Nuclear Information System (INIS)

    The infrared and visible cooperative emissions of ytterbium ions are studied in Yb-doped NdVO4 single crystals. The absorption of optical phonons allows the emissions at room temperature when a Nd:YAG laser is used. Low temperature emissions are observed due to the Nd3+?Yb3+ energy transfer following an argon ion laser excitation of the Nd3+ ions. Analysis of the cooperative emission at low doping concentration (1%) indicates that it is generated by distant pair forming Yb3+ ions while at high doping concentration (? 5%) close ions magnetically coupled and superexchange mechanisms prevail in the emitting process. - Research highlights: ? Cooperative emission in Yb:NdVO4. ? Excitation of the cooperative emission (phonon assisted or with sensitizer ions). ? Role of the superexchange mechanism in the high doping regime.

  19. VoIP over WMN: Effect of packet aggregation

    Directory of Open Access Journals (Sweden)

    Khyati Marwah,

    2011-06-01

    Full Text Available VoIP services are getting more and more popular day by day. In order to meet the users demand for such services irrespective of users location requires wide area wireless coverage .To this extent,wireless mesh networks have been considered as practical and inexpensive solution .In order to improve the performance of VoIP services, techniques like packet aggregation are done . This paper focuses on finding the effect of packet aggregation on various parameters like aggregation delay, end to end delay and MOS etc. Results obtained through simulations done on Qualnet Simulator concludes that packet aggregation is justified upto a certain extent only as after that most of the users get dissatisfied.

  20. Electrocaloric effect of metal-insulator transition in VO2

    Science.gov (United States)

    Matsunami, Daichi; Fujita, Asaya

    2015-01-01

    The electrocaloric effect was observed in association with an electric-field induced metal-insulator transition in VO2 using a calorimetric measurement under an applied voltage. For a VO2 plate with a 0.4 mm thickness located in the center of a capacitor-like structure, the metal-insulator transition was manipulated by applying a few volts. The occurrence of a transition in such a thick sample with relatively low voltage indicates that a surface charge accumulation mechanism is effective. The isothermal entropy change reached 94 J kg-1 K-1, while the adiabatic temperature change was calculated as -3.8 K under a voltage change of 0-3 V. The large entropy change is attributed to correlation of the complex freedom among spin, charge, and lattice.

  1. CAN WE CONFIDENTLY STUDY VO2 KINETICS IN YOUNG PEOPLE?

    Directory of Open Access Journals (Sweden)

    Samantha G. Fawkner

    2007-09-01

    Full Text Available The study of VO2 kinetics offers the potential to non-invasively examine the cardiorespiratory and metabolic response to dynamic exercise and limitations to every day physical activity. Its non-invasive nature makes it hugely attractive for use with young people, both healthy and those with disease, and yet the literature, whilst growing with respect to adults, remains confined to a cluster of studies with these special populations. It is most likely that this is partly due to the methodological difficulties involved in studying VO2 kinetics in young people which are not present, or present to a lesser degree, with adults. This article reviews these methodological issues, and explains the main procedures that might be used to overcome them

  2. Chapter 11: Web-based Tools - VO Region Inventory Service

    Science.gov (United States)

    Good, J. C.

    As the size and number of datasets available through the VO grows, it becomes increasingly critical to have services that aid in locating and characterizing data pertinent to a particular scientific problem. At the same time, this same increase makes that goal more and more difficult to achieve. With a small number of datasets, it is feasible to simply retrieve the data itself (as the NVO DataScope service does). At intermediate scales, "count" DBMS searches (searches of the actual datasets which return record counts rather than full data subsets) sent to each data provider will work. However, neither of these approaches scale as the number of datasets expands into the hundreds or thousands. Dealing with the same problem internally, IRSA developed a compact and extremely fast scheme for determining source counts for positional catalogs (and in some cases image metadata) over arbitrarily large regions for multiple catalogs in a fraction of a second. To show applicability to the VO in general, this service has been extended with indices for all 4000+ catalogs in CDS Vizier (essentially all published catalogs and source tables). In this chapter, we will briefly describe the architecture of this service, and then describe how this can be used in a distributed system to retrieve rapid inventories of all VO holdings in a way that places an insignificant load on any data supplier. Further, we show and this tool can be used in conjunction with VO Registries and catalog services to zero in on those datasets that are appropriate to the user's needs. The initial implementation of this service consolidates custom binary index file structures (external to any DBMS and therefore portable) at a single site to minimize search times and implements the search interface as a simple CGI program. However, the architecture is amenable to distribution. The next phase of development will focus on metadata harvesting from data archives through a standard program interface and distribution of the search processing across multiple service providers for redundancy and parallelization.

  3. VO2 thermochromic smart window for energy savings and generation

    OpenAIRE

    Jiadong Zhou; Yanfeng Gao; Zongtao Zhang; Hongjie Luo; Chuanxiang Cao; Zhang Chen; Lei Dai; Xinling Liu

    2013-01-01

    The ability to achieve energy saving in architectures and optimal solar energy utilisation affects the sustainable development of the human race. Traditional smart windows and solar cells cannot be combined into one device for energy saving and electricity generation. A VO2 film can respond to the environmental temperature to intelligently regulate infrared transmittance while maintaining visible transparency, and can be applied as a thermochromic smart window. Herein, we report for the first...

  4. Study of LiMgVO4 electrical conductivity mechanism

    OpenAIRE

    Paraskeva, C.; Kazakopoulos, A.; Chrissafis, K.; Kalogirou, O.

    2010-01-01

    This paper deals with impedance spectroscopy on single-phase polycrystalline LiMgVO4 in the temperature range of 25–500 °C. Thermogravimetric measurements show a weight loss of 2.7% in the temperature range between 25 °C and 175 °C due to humidity desorption. A conductivity mechanism along the grain boundaries (agb) is identified in the specific temperature range and is attributed to a reversible humidity absorption–desorption mechanism. Equivalent circuits are drawn using the results ...

  5. Implementation of Cloud Computing into VoIP

    OpenAIRE

    Gerea, Floriana

    2012-01-01

    This article defines Cloud Computing and highlights key concepts, the benefits of using virtualization, its weaknesses and ways of combining it with classical VoIP technologies applied to large scale businesses. The analysis takes into consideration management strategies and resources for better customer orientation and risk management all for sustaining the Service Level Agreement (SLA). An important issue in cloud computing can be security and for this reason there are several security solu...

  6. Crystal structure of ferroelectric Bi2VO5.5

    International Nuclear Information System (INIS)

    The structure of the ?-phase of bismuth vanadate Bi2VO5.5 has been determined using single crystal X-ray diffraction data in the space group Aba2. The refinement involves a well defined disorder at the vanadium site, which incorporates the features of the superlattice structure with vanadium tetrahedra and oxygen-deficient octahedra that is displaced about the twofold axis

  7. Temporal aspects of the VO2 response at the power output associated with VO2peak in well trained cyclists--implications for interval training prescription.

    Science.gov (United States)

    Laursen, Paul B; Shing, Cecilia M; Jenkins, David G

    2004-12-01

    The power output achieved at peak oxygen consumption (VO2peak) and the time this power can be maintained (i.e., Tmax) have been used in prescribing high-intensity interval training. In this context, the present study examined temporal aspects of the VO2 response to exercise at the cycling power that output well trained cyclists achieve their VO2peak (i.e., Pmax). Following a progressive exercise test to determine VO2peak, 43 well trained male cyclists (M age = 25 years, SD = 6; M mass = 75 kg, SD = 7; M VO2peak = 64.8 ml x kg(-1) x min(-1), SD = 5.2) performed two Tmax tests 1 week apart. Values expressed for each participant are means and standard deviations of these two tests. Participants achieved a mean VO2peak during the Tmax test after 176 s (SD = 40; M = 74% of Tmax, SD = 12) and maintained it for 66 s (SD = 39; M = 26% of Tmax, SD = 12). Additionally, they obtained mean 95% of VO2peak after 147 s (SD = 31; M = 62% of Tmax, SD = 8) and maintained it for 95 s (SD = 38; M = 38% of Tmax, SD = 8). These results suggest that 60-70% of Tmax is an appropriate exercise duration for a population of well trained cyclists to attain VO2peak during exercise at Pmax. However, due to intraparticipant variability in the temporal aspects of the VO2 response to exercise at Pmax, future research is needed to examine whether individual high-intensity interval training programs for well trained endurance athletes might best be prescribed according to an athlete's individual VO2 response to exercise at Pmax. PMID:15673041

  8. Nonreciprocal switching of VO2 thin films on microstructured surfaces

    Science.gov (United States)

    Adams, Charles; Karakurt, Ismail; Leiderer, Paul; Boneberg, Johannes; Haglund, Richard

    2010-10-01

    Vanadium dioxide is a strongly correlated electron material that undergoes an insulator-to-metal transition at approximately 340 K, with a corresponding large change in its optical and electronic properties. By depositing a VO2 thin film on a planar hexagonal close-packed array of 1.54 ?m diameter silica microspheres, we constructed a laser-triggered thin film optical switch that exhibits different fluence thresholds for the insulator-metal transition (IMT) depending on the direction of illumination. The IMT was triggered by a ns Nd:YAG laser (532 nm) from two directions normal to the substrate while monitoring the transmission with a near-IR diode laser. Due to the focusing effects of the microspheres, the fluence required for switching the VO2 was 2.4 times higher when the switching laser was incident from the film (top) side of the array than from the microsphere (bottom) side. Through both the experiments and simulations, we find evidence for strong nonlinear near-field absorption in the VO2.

  9. Relative Aerial Biomass Yield of Intercroped Alfalfa with Winter Forage Cereals / Rendimiento Relativo de Biomasa Aérea en Intercultivos de Alfalfa con Cereales Forrajeros de Invierno

    Scientific Electronic Library Online (English)

    Telmo, Pereyra; Héctor, Pagliaricci; Alfredo, Ohanian.

    2008-09-01

    Full Text Available SciELO Chile | Language: English Abstract in spanish En las regiones tropicales del mundo, el intercultivo está asociado con la producción de granos para la alimentación, mientras que en áreas templadas recibe mayor atención como medio de producción eficiente de forraje. El objetivo de este experimento fue determinar el rendimiento relativo de biomasa [...] aérea en intercultivos de alfalfa (Medicago sativa L.) y cereales forrajeros de invierno. Se establecieron ocho sistemas producto de la combinación con especies de cereales con distintas fechas de siembra. Las mediciones de biomasa se realizaron en tres situaciones: monocultivo de alfalfa, monocultivo de cereales e intercultivo de alfalfa-cereal, calculándose el rendimiento relativo del intercultivo (RRI). Se empleó un diseño con arreglo bifactorial y dos repeticiones en bloques completos al azar. Los intercultivos de alfalfa-cereal generaron valores de RRI entre 0,71 y 0,83, lo que indicó que en una misma superficie es posible producir entre el 71 y 83% de la biomasa que ambos cultivos producirían en superficies separadas. Abstract in english In the tropical regions of the world, intercropping is mostly associated with food grain production, whereas it is receiving increased attention in temperate regions as a means of efficient forage production. The aim of this work was to determine the relative yield of aerial biomass in alfalfa or lu [...] cerne (Medicago sativa L.) and winter forage cereals intercrops. These were done in eight systems resulting from the combination of species sown at different dates. The biomass was measured in three situations: alfalfa and cereal sole-crop and alfalfa-cereal intercrops, the relative biomass yields were calculated by the relative yield index (RYI). The field experiment was conducted as a bifactorial array in a randomized complete block design of two replicates. The alfalfa-cereal intercrops provided RYI values ranging from 0.71 to 0.83. This showed that it is possible to produce, in the same area, between 71 and 83% of the biomass that both crops would produce in separate ones.

  10. Aprovechamiento de Biomasa Peletizada en el Sector Ladrillero en Bogotá-Colombia: Análisis Energético y Ambiental / Use of Pelleted Biomass in the Brick Industry in Bogota-Colombia: Energy and Environmental Analysis

    Scientific Electronic Library Online (English)

    César A, García-Ubaque; Martha L, Vaca-Bohórquez; Gabriel F, Talero.

    Full Text Available En este estudio se compara el desempeño energético y ambiental del uso de combustibles a partir de dos tipos de biomasas peletizadas: residuos de madera, provenientes de podas y residuos de la producción de muebles, principalmente aserrín. La biomasa proveniente de residuos de madera es uno de los m [...] ateriales más adecuados para utilizar como combustible alternativo. El sector ladrillero tiene una gran demanda energética para sus procesos de secado y cocción y el uso de combustibles alternativos a partir de biomasa permite obtener reducciones importantes en emisiones atmosféricas y no afecta las condiciones técnicas del proceso de producción de ladrillos. La biomasa con mejor desempeño, tanto en las variables energéticas como ambientales evaluadas, fue el aserrín. Abstract in english This study compared the energy and environmental performance of fuels from two types of pelleted biomass: wood waste from pruning and waste from furniture production, mainly sawdust. Wood residues biomass is one of the most suitable materials for using as an alternative fuel. The brick manufacture s [...] ector has a high energy demand for its drying and firing processes and the use of alternative fuels from biomass allows significant reductions in emissions and does not affect the technical conditions of the process of brick production. The biomass with better performance was sawdust, which presented the optimum energy and environmental variables.

  11. Influencia de la variabilidad edafica en la producción de biomasa del cultivo de la uña de gato uncaria tomentosa (willd d.c. en la cuenca del río aguaytia, region Ucayali -Perú

    Directory of Open Access Journals (Sweden)

    Teresa E. Mech\\u00E1n

    2007-01-01

    Full Text Available En Mayo 2003 se instalaron cuatro plantaciones de uña de gato Uncaria tomentosa (Willd D.C a lo largo de la Cuenca del Río Aguaytia en Ucayali Perú. Las plantas correspondieron al clon 11, propagadas in vitro, y procedentes del Instituto de Biotecnología (IBT de la Universidad Nacional Agraria La Molina (UNALM. El estudio se basó en la determinación de la influencia edáfica en la producción de biomasa de esta especie como cultivo. Las áreas experimentales se encuentran a diferentes niveles altitudinales desde los 136 hasta los 884 msnm. En Junio 2005 se realizó la primera poda y el muestreo de suelos a dos profundidades, de 0 a 15 y de 15 a 30 cm del suelo.La textura arcillosa en los suelos fueron las que correlacionaron mejor con la producción de la biomasa del clon; siendo las ecuaciones más representativas: a Biomasa = 27.329(% Arena - 51.875 y b Biomasa = -32.247(arcilla ? 2169.8. Los indicadores mas significativos de la fertilidad del suelo en el proceso de adaptación de esta especie como cultivo fueron: los contenidos de fósforo (P, materia orgánica (M.O., nitrógeno (N total, saturación de aluminio (% Al, potasio (K, magnesio (Mg y el pH

  12. A importância do limiar anaeróbio e do consumo máximo de oxigênio (VO2 máx.) em jogadores de futebol / The importance of the anaerobic threshold and maximum oxygen uptake (VO2 PEAK) for soccer players

    Scientific Electronic Library Online (English)

    Paulo Roberto Santos, Silva; Angela, Romano; Alberto Azevedo Alves, Teixeira; Ana Maria, Visconti; Carla Dal Maso Nunes, Roxo; Gilberto Silva, Machado; José Roberto Rivelino, Vidal; Luís Antonio, Inarra.

    1999-12-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste estudo foi fazer uma abordagem sobre a importância do limiar anaeróbio (LA) e o consumo máximo de oxigênio (VO2máx.) em jogadores de futebol e comparar os resultados encontrados em nossos futebolistas com os da literatura especializada. Foram avaliados 18 jogadores de futebol profis [...] sional, com média de idade de 24 ± 4 anos, peso de 72,5 ± 5,9kg; estatura de 176,5 ± 7,0cm e superfície corpórea de 1,91 ± 0,15m². Todos os atletas foram avaliados após um período de dois meses de treinamentos. Os futebolistas foram submetidos a teste máximo em esteira ergométrica, utilizando-se protocolo escalonado e contínuo. A resposta de freqüência cardíaca (FC) foi registrada por meio de um eletrocardiógrafo (HeartWare) de 12 derivações simultâneas e, a pressão arterial (PA), por meio de método auscultatório. A ventilação pulmonar (V E), o consumo de oxigênio (VO2), a produção de dióxido de carbono (VCO2) e a razão de troca respiratória (RER) foram avaliados por método espirométrico computadorizado respiração-a-respiração (MedGraphics Corporation [MGC]). Os seguintes resultados foram verificados: no (LA): [FC = 173,6 ± 8,6bpm; VO2 = 55,78 ± 5,93ml.kg.-1.min-1; velocidade = 14,6 ± 1,0km.h-1]; no exercício máximo [FC = 189,5 ± 11,4bpm; V E = 134,1 ± 15,9L.min-1; VO2máx. = 63,75 ± 4,93ml.kg.-1.min-1; velocidade = 17,8 ± 1,0km.h-1; Borg = 18,3 ± 1,3 pontos]. Concluindo: Os resultados, comparados com os da literatura especializada na modalidade futebol, demonstraram que os índices de LA e VO2máx. foram semelhantes e, até mesmo, superiores a vários de estudos publicados sobre essas duas variáveis em jogadores de futebol profissional. Entretanto, considerando as posições dos jogadores, não há um consenso definido sobre os índices mais adequados de LA e VO2máx. em futebolistas, mas, sim, sugestões. Abstract in english The aim of this study was to make an approach on the importance of the anaerobic threshold (AT) and the peak oxygen uptake in soccer players, and compare the results found in players to those existing in the specialized literature. An evaluation was made in 18 professional soccer players aged 24 ± 4 [...] ; weight 72.5 ± 5.9 kg; height 176.5 ± 7.0 cm, and body surface 1.91 ± 0.15 m². Every athlete was evaluated after a 2 month training period. The soccer players were submitted to a maximum exercise test on treadmill, using incremental continuous protocol. The heart rate (HR) was recorded by means of an electrocardiograph (HeartWare) with 12 simultaneous leads and the arterial blood pressure (BP) by auscultation method. The pulmonary ventilation (V E), the oxygen uptake (VO2), the carbon dioxide production (VCO2) and the respiratory exchange rate (RER) were evaluated by means of the breath-by-breath spirometric computerized method (MedGraphics Corporation-MGC). The following results were verified in the AT: HR = 173.6 ± 8.6 bpm; VO2 = 55.78 ± 5.93 mlO2.kg-1.min-1; running velocity = 14.6 ± 1.0 km.h-1; maximum exercise: HR = 189.5 ± 11.4 bpm; V E = 134.1 ± 15.9 L.min-1; VO2 peak = 63.75 ± 4.93 mlO2.kg-1.min-1; maximum velocity = 17.8 ± 1.0 km.h-1; Borg scale = 18.3 ± 1.3 points. In conclusion, the results, when compared to those of specialized literature, proved the rate of AT and VO2 peak to be similar and even superior to several results published about such two variables in professional soccer players. Considering, however, the players' position, there is no definite consensus on the most adequate AT rates and VO2 peak in soccer players, but only suggestions.

  13. Laser properties of continuous-grown GdVO4/Nd:GdVO4 composite crystal

    International Nuclear Information System (INIS)

    Effective CW and A-O Q-switched laser operations were demonstrated firstly using a continuous-grown GdVO4/Nd:GdVO4 composite rod. A maximum CW output power of 19.2 W was obtained with the slope efficiency of 79.6% and the maximum optical-optical efficiency of 73.0% to absorbed pump power. In A-O Q-switched operation, the pulse width of 15.0 ns, 10.6 ns, and 6.9 ns, the peak power of about 11.3 kW, 29.6 kW, and 130.4 kW were achieved at the repetition rate of 100 kHz, 50 kHz, and 10 kHz, respectively

  14. Zn(1.86)Cd(0.14)(OH)VO(4).

    Science.gov (United States)

    Dor?evi?, Tamara; Stojanovi?, Jovica; Karanovi?, Ljiljana

    2010-01-01

    The title compound, dizinc cadmium hydroxide tetraoxido-vanadate, Zn(1.86)Cd(0.14)(OH)VO(4), was prepared under low-temperature hydro-thermal conditions. It is isostructural with Zn(2)(OH)VO(4) and Cu(2)(OH)VO(4). In the crystal structure, chains of edge-sharing [ZnO(6)] octahedra are inter-connected by VO(4) tetra-hedra (site symmetries of both V atoms and their coordination polyhedra are .m.) to form a three-dimensional [Zn(OH)VO(4)](2-) framework with channels occupied by Zn and Zn/Cd cations adopting trigonal-bipyramidal and distorted octa-hedral coordinations, respectively. Zn(1.86)Cd(0.14)(OH)VO(4) is topologically related to adamite-type phases, and descloizite- and tsumcorite-type structures. PMID:21589202

  15. Zn1.86Cd0.14(OH)VO4

    Science.gov (United States)

    ?or?evi?, Tamara; Stojanovi?, Jovica; Karanovi?, Ljiljana

    2010-01-01

    The title compound, dizinc cadmium hydroxide tetraoxido­vanadate, Zn1.86Cd0.14(OH)VO4, was prepared under low-temperature hydro­thermal conditions. It is isostructural with Zn2(OH)VO4 and Cu2(OH)VO4. In the crystal structure, chains of edge-sharing [ZnO6] octahedra are inter­connected by VO4 tetra­hedra (site symmetries of both V atoms and their coordination polyhedra are .m.) to form a three-dimensional [Zn(OH)VO4]2? framework with channels occupied by Zn and Zn/Cd cations adopting trigonal–bipyramidal and distorted octa­hedral coordinations, respectively. Zn1.86Cd0.14(OH)VO4 is topologically related to adamite-type phases, and descloizite- and tsumcorite-type structures. PMID:21589202

  16. Building a VO-compliant Radio Astronomical DAta Model for Single-dish radio telescopes (RADAMS)

    CERN Document Server

    Santander-Vela, J D; Leon, S; Espigares, V; Ruiz, J E; Verdes-Montenegro, L; Solano, E

    2012-01-01

    The Virtual Observatory (VO) is becoming the de-facto standard for astronomical data publication. However, the number of radio astronomical archives is still low in general, and even lower is the number of radio astronomical data available through the VO. In order to facilitate the building of new radio astronomical archives, easing at the same time their interoperability with VO framework, we have developed a VO-compliant data model which provides interoperable data semantics for radio data. That model, which we call the Radio Astronomical DAta Model for Single-dish (RADAMS) has been built using standards of (and recommendations from) the International Virtual Observatory Alliance (IVOA). This article describes the RADAMS and its components, including archived entities and their relationships to VO metadata. We show that by using IVOA principles and concepts, the effort needed for both the development of the archives and their VO compatibility has been lowered, and the joint development of two radio astronom...

  17. Producción de biomasa y costos de producción de pastos Estrella Africana (Cynodon nlemfuensis), kikuyo (Kikuyuocloa clandestina) y Ryegrass Perenne (Lolium perenne) en lecherías de Costa Rica

    Scientific Electronic Library Online (English)

    Luis, Villalobos; Jose, Arce; Rodolfo, WingChing.

    2013-12-01

    Full Text Available SciELO Costa Rica | Language: Spanish Abstract in spanish Se evaluó la producción de biomasa, los costos de producción y el costo del kilogramo de materia seca en los pastos kikuyo (Kikuyuocloa clandestina), ryegrass perenne (Lolium perenne) y estrella africana (Cynodon nlemfuensis), a lo largo de un año, en 8 fincas comerciales ubicadas en las provincias [...] de Cartago (2), San José (2) y Alajuela (4). La producción de biomasa promedio por ciclo para los 3 pastos fue de 3395 kg.ha-1 MS; la producción anual se ve influenciada por los días de recuperación de cada especie, mostrando valores de 40 170, 38 731 y 28 995 kg.ha-1 de MS para los pastos estrella africana, kikuyo y ryegrass perenne, espectivamente. La producción de biomasa varía durante el año y en las épocas de mayor producción de esa biomasa, los animales tienen un menor aprovechamiento de la pastura en términos porcentuales, debido a que la carga animal, los períodos de permanencia y las áreas de pastoreo no se ajustan a la disponibilidad de forraje. Los costos anuales de mano de obra, insumos y tierra promedio fueron de 72.433, 505.515 y 18.760 colones.ha-1, respectivamente; siendo los insumos el rubro con un peso relativo mayor en la estructura de costos de las fincas en pastoreo. Los costos del kg de MS producido y consumido, para los 3 pastos evaluados, fueron de 16,6 y 44,4 colones respectivamente, siendo el aprovechamiento que los animales hacen de las pasturas el determinante del costo del material consumido. Las fincas con mayor inversión anual en pasturas, mostraron un mayor retorno en kg.ha-1 leche. Abstract in english Dry matter yield and production costs in grazing systems on dairy farms of Costa Rica. Biomass production costs and dry matterkilogram cost were evaluated in kikuyu grass (Kikuyuocloa clandestina), perennial ryegrass (Lolium perenne) and African stargrass (Cynodon nlemfuensis), along one year, in 8 [...] dairy farms located in Cartago (2), San José (2) and Alajuela (4) provinces. Average dry matter yield per cycle was 3395 kg.ha-1 DM for the three grasses. Annual yield is influenced by the regrowth period of each species, with values of 40 170, 38 731 and 28 995 kg.ha-1 DM for African stargrass, kikuyu grass and perennial ryegrass, respectively. Biomass production varies during the year, and the utilization by cattle has a less utilization of these fields during the months of highest yield. Since the stocking rate, the occupational period and the grazing area are not adjusted an the basis of dry matter availability, dairy cattle has a lower utilization rate in the paddocks. Average costs for labor, agricultural inputs and land were (in Costa Rican currency) 72.433, 505.515 and 18.760 colones.ha-1, respectively. Inputs had the highest impact in the costs structure in grazing dairy farms. Costs for dry matter kilogram produced and consumed were 16.6 and 44.4 colones, respectively, for all 3 pastures; the cost of dry matter-kilogram consumed was affected by the rate of utilization in the grazing paddocks. Dairy farms with higher investment in pastures had a higher return in kg.ha-1 milk as well.

  18. Biomass distribution in declining sacred-fir seedlings / DECLÍNIO DA BIOMASSA EM MUDAS DE "SACRED-FIR" PLÂNTULAS) / DISTRIBUCIÓN DE BIOMASA EN PLÁNTULAS DE OYAMEL EN DECLINACIÓN

    Scientific Electronic Library Online (English)

    Miguel Ángel, López-López; Alejandro, Velázquez-Martínez; Juan, Acosta-Montoya; Elizabeth, Estañol-Botello.

    2006-06-01

    Full Text Available SciELO Venezuela | Language: English Abstract in portuguese Nos bosques localizados no Sudoeste da Cidade do México tem-se observado uma declinação do oyamel Abies religiosa (H.B.K.) Schl. et Cham. Durante os últimos 25 anos. A caracterização deste fenômeno desde diferentes pontos de vista é importante si se pretende incrementar o conhecimento sobre o proble [...] ma e propor soluções viáveis. Por esta razão se estudaram as mudanças nos padrões de distribuição de biomassa em plântulas de 7 anos de idade, como resultado da declinação. Estabeleceu-se um experimento completamente aleatório com três níveis de dano como tratamentos: ligeiro, intermediário e severo, e oito repetições por tratamento. A biomassa dos componentes das plântulas se reduziu significativamente a medida que se incrementou o dano. A raíz foi o componente mais afetado, seguido dos galhos. No entanto, estas últimas acumularam biomassa com o tempo, produzindo um desbalanço entre a biomassa aérea e subterrânea. Mesmo quando este desbalanço se compensa pela queda da folhagem, traz como consequência uma redução da quantidade de carbono fixado. Abstract in spanish En los bosques localizados en el oeste y suroeste de la Ciudad de México se ha observado una declinación del oyamel Abies religiosa (H.B.K.) Schl. et Cham. durante los últimos 25 años. La caracterización de este fenómeno desde diferentes puntos de vista es importante si se pretende incrementar el co [...] nocimiento sobre el problema y proponer soluciones viables. Por esta razón se estudiaron los cambios en los patrones de distribución de biomasa en plántulas de 7 años de edad, como resultado de la declinación. Se estableció un experimento completamente al azar con tres niveles de daño como tratamientos: ligero, intermedio y severo, y ocho repeticiones por tratamiento. La biomasa de los componentes de las plántulas se redujo significativamente a medida que se incrementó el daño. La raíz fue el componente más afectado, seguido de las ramillas. Sin embargo, estas últimas acumularon biomasa con el tiempo, produciendo un desbalance entre la biomasa aérea y subterránea. Aun cuando este desbalance se compensa por la caída de follaje, trae como consecuencia una reducción de la cantidad de carbono fijado. Abstract in english In the forests located west and southwest of Mexico City, decline of sacred-fir Abies religiosa (H.B.K.) Schl. et Cham. has been observed for the past 25 years. Characterization of the phenomenon from different viewpoints is important if knowledge of the problem is to be increased and viable solutio [...] ns pursued. For this reason, changes in biomass allocation patterns, as a consequence of decline in 7-year-old seedlings were investigated. A completely randomized experiment with three degrees of damage as treatments: slight, intermediate and severe; and eight replicates per treatment was established. The biomass of the seedling components was significantly reduced as the damage increased. Root was the most affected organ followed by twigs. However, twigs accumulated biomass through time producing an imbalance between aboveground and root biomass. Even though this imbalance is offset by leaf fall, this brings about a further reduction in the amount of carbon fixed.

  19. Modelo dinámico de crecimiento de la biomasa para Mytilus chilensis en sistemas de cultivo en líneas / Dynamic biomass growth model for Mytilus chilensis in longline culture systems

    Scientific Electronic Library Online (English)

    José, Marambio; Sergio, Maturana; Bernardita, Campos.

    2012-04-01

    Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Este estudio propone un modelo de crecimiento dinámico de la biomasa para el bivalvo Mytilus chilensis, en sistemas de cultivos en línea. El modelo propuesto determina la biomasa a través del peso medio total y el número de choritos por metro lineal en la cuerda de engorda, calibrado usando datos re [...] ales. El peso medio se determina a través del modelo de von Bertalanffy modificado que incorpora la disponibilidad de alimento del ambiente y el ciclo reproductivo a través del Índice de Rendimiento Productivo, el que corresponde al cociente entre el peso en carne y el peso total. Por lo anterior, el peso medio está determinado por la disponibilidad de alimento y el crecimiento biológico de la especie. El modelo supone que el número de individuos de choritos por metro en la cuerda es el resultado tanto de la competencia intraespecífica entre individuos de M. chilensis como de la interespecífica con individuos del mitílido Aulacomya atra por el espacio disponible en la misma cuerda. Para modelar la competencia por el espacio disponible se utilizó la tasa de crecimiento, la superficie ocupada por los individuos y el porcentaje de presencia de M. chilensis y de A. atra. El estudio se realizó en la cuenca de Rilán, isla de Chiloé, sur de Chile, por un periodo de 18 meses. Se obtuvo un R² ajustado = 0,98, 0,93, y 0,94 para la variación del tamaño, de la densidad lineal y la biomasa, respectivamente, lo que indica que el modelo propuesto puede ser utilizado para predecir la biomasa en el tiempo. Abstract in english A dynamic biomass growth model for the mussel Mytilus chilensis in longline culture systems in proposed. This model determines the biomass by estimating the average weight and the number of mussels per meter of seeded rope, using real data. The average weight is estimated using the von Bertalanffy m [...] odel modified to incorporate the availability of food in the environment and the reproductive cycle given by the Meat Yield Index, which is the quotient between the meat weight and the total weight. Therefore, the average weight is determined by the availability of food and the biological growth of the species. The model assumes that the number of mussel individuals per meter in the rope is the result of both the species intraspecific competition among M. chilensis individuals and the interspecific competition with individuals of the mytilid Aulacomya atra for the available space in the same seeded rope. The growth rate, the occupied surface and the presence percentage of M. chilensis and A. atra were used to model the competition for the available space. The study was performed at the Rilán basin in the Chiloé Island, southern Chile, during an 18-month period. The results obtained were an R² adjusted = 0.98, 0.93, and 0.94 for the variation in size, lineal density and biomass, respectively, which indicate that the proposed dynamic model can be used to predict the biomass over time.

  20. Efficient removal rhodamine B over hydrothermally synthesized fishbone like BiVO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Xue, E-mail: jlsdlinxue@126.com [College of Chemistry, Key Laboratory of Preparation and Application Environmentally Friendly Materials of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province (China); Li, Hongji [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu Province (China); Yu, Lili; Zhao, Han [College of Chemistry, Key Laboratory of Preparation and Application Environmentally Friendly Materials of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province (China); Yan, Yongsheng [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu Province (China); Liu, Chunbo; Zhai, Hongjv [College of Chemistry, Key Laboratory of Preparation and Application Environmentally Friendly Materials of the Ministry of Education, Jilin Normal University, Siping 136000, Jilin Province (China)

    2013-10-15

    Graphical abstract: - Highlights: • Fishbone like BiVO{sub 4} product was synthesized through hydrothermal method. • BiVO{sub 4} sample was characterized by various characterization technologies. • Fishbone like BiVO{sub 4} presented outstanding photocatalytic performance. - Abstract: Fishbone like BiVO{sub 4} product has been successfully synthesized by a hydrothermal method without using any surfactant or template. The pH value was found to play an important role in the formation of this morphology. The band gap of the as-prepared fishbone like BiVO{sub 4} sample was estimated to be about 2.36 eV from the onset of UV–vis diffuse reflectance spectrum (UV–vis DRS) of the photocatalyst. The as-prepared fishbone like BiVO{sub 4} sample exhibited excellent visible-light-driven photocatalytic efficiency. Over this catalyst, the 100% degradation of rhodamine B (Rh B) (0.005 mmol L{sup ?1}) was obtained after visible light irradiation (? > 420 nm) for 180 min. This is much higher than that of bulk BiVO{sub 4} sample prepared by solid-state reaction. The reason for the differences in the photocatalytic activities of fishbone like BiVO{sub 4} sample and bulk BiVO{sub 4} sample was further investigated.

  1. IAX-Based Peer-to-Peer VoIP Architecture

    OpenAIRE

    Lazzez, Amor; Fredj, Ouissem Ben; Slimani, Thabet

    2013-01-01

    Nowadays, Voice over IP (VoIP) constitutes a privileged field of service innovation. One benefit of the VoIP technology is that it may be deployed using a centralized or a distributed architecture. One of the most efficient approaches used in the deployment of centralized VoIP systems is based on the use of IAX (Inter-Asterisk Exchange), an open-source signaling/data exchange protocol. Even though they are currently widely used, client-server VoIP systems suffer from many we...

  2. Interaction of VO2+ ion and some insulin-enhancing compounds with immunoglobulin G.

    Science.gov (United States)

    Sanna, Daniele; Micera, Giovanni; Garribba, Eugenio

    2011-04-18

    Complexation of VO(2+) ion with the most abundant class of human immunoglobulins, immunoglobulin G (IgG), was studied using EPR spectroscopy. Differently from the data in the literature which report no interaction of IgG with vanadium, in the binary system VO(2+)/IgG at least three sites with comparable strength were revealed. These sites, named 1, 2, and 3, seem to be not specific, and the most probable candidates for metal ion coordination are histidine-N, aspartate-O or glutamate-O, and serinate-O or threoninate-O. The mean value for the association constant of (VO)(x)IgG, with x = 3-4, is log ? = 10.3 ± 1.0. Examination of the ternary systems formed by VO(2+) with IgG and human serum transferrin (hTf) and human serum albumin (HSA) allows one to find that the order of complexing strength is hTf ? HSA ? IgG. The behavior of the ternary systems with IgG and one insulin-enhancing agent, like [VO(6-mepic)(2)], cis-[VO(pic)(2)(H(2)O)], [VO(acac)(2)], and [VO(dhp)(2)], where 6-mepic, pic, acac, and dhp indicate the deprotonated forms of 6-methylpicolinic and picolinic acids, acetylacetone, and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone, is very similar to the corresponding systems with albumin. In particular, at the physiological pH value, VO(6-mepic)(IgG)(OH), cis-VO(pic)(2)(IgG), and cis-VO(dhp)(2)(IgG) are formed. In such species, IgG coordinates nonspecifically VO(2+) through an imidazole-N belonging to a histidine residue exposed on the protein surface. For cis-VO(dhp)(2)(IgG), log ? is 25.6 ± 0.6, comparable with that of the analogous species cis-VO(dhp)(2)(HSA) and cis-VO(dhp)(2)(hTf). Finally, with these new values of log ?, the predicted percent distribution of an insulin-enhancing VO(2+) agent between the high molecular mass (hTf, HSA, and IgG) and low molecular mass (lactate) components of the blood serum at physiological conditions is calculated. PMID:21434616

  3. Speciation of insulin-mimetic VO(IV)-containing drugs in blood serum.

    Science.gov (United States)

    Kiss, T; Kiss, E; Garribba, E; Sakurai, H

    2000-05-30

    The biospeciations of three potential insulin-mimetic VO(IV) compounds, VO(maltolate)2, VO(picolinate)2 and VO(6-Me-picolinate)2, in blood serum were assessed via modelling calculations, using the stability constants reported in the literature for the binary insulin-mimetic complexes and their ternary complexes formed with the most important low molecular mass binders in the serum: oxalic acid, lactic acid, citric acid and phosphate. The binding capabilities of two high molecular mass serum proteins, albumin and transferrin, were also taken into account. PMID:10885465

  4. Temperature-agile and structure-tunable optical properties of VO2/Ag thin films

    International Nuclear Information System (INIS)

    By integrating together VO2's unique near-room-temperature (RT) semiconductor-metal (S-M) phase transition with a thin silver (Ag) layer's plasmonic properties, VO2/Ag multilayers could present a much enhanced optical transmission change when increasing the temperature from RT to over VO2's S-M phase-transition temperature. Changing VO2 and Ag layer thicknesses can also significantly tune their transmission and absorption properties, which could lead to a few useful designs in optoelectronic and energy-saving industries. (orig.)

  5. Spectroscopic analysis in the virtual observatory environment with SPLAT-VO

    Science.gov (United States)

    Škoda, P.; Draper, P. W.; Neves, M. C.; Andreši?, D.; Jenness, T.

    2014-11-01

    SPLAT-VO is a powerful graphical tool for displaying, comparing, modifying and analysing astronomical spectra, as well as searching and retrieving spectra from services around the world using Virtual Observatory (VO) protocols and services. The development of SPLAT-VO started in 1999, as part of the Starlink StarJava initiative, sometime before that of the VO, so initial support for the VO was necessarily added once VO standards and services became available. Further developments were supported by the Joint Astronomy Centre, Hawaii until 2009. Since end of 2011 development of SPLAT-VO has been continued by the German Astrophysical Virtual Observatory, and the Astronomical Institute of the Academy of Sciences of the Czech Republic. From this time several new features have been added, including support for the latest VO protocols, along with new visualization and spectra storing capabilities. This paper presents the history of SPLAT-VO, its capabilities, recent additions and future plans, as well as a discussion on the motivations and lessons learned up to now.

  6. [Study on spectral property of phase transition of PcNi-VO2 films].

    Science.gov (United States)

    Yuan, Hong-tao; Feng, Ke-cheng; Zhang, Xian-hui

    2007-10-01

    Highly oriented VO2 thin films were deposited on sapphire substrate and [C8H17O]8 PcNi thin films were spin-coated onto VO2 thin films. The microstructure of VO2 thin films was studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO2 multilayer-films were investigated with infrared spectrometer. It was found that the mid-infrared transmittance of the complex films in the wavelength range 1.5 to 5.5 mm raised with PcNi coating. The thermochromism of PcNi/VO2 films did not changed compared with VO2 films and the transition temperature was the same as that of VO2. It can be anticipated that the optical limiting property of PcNi/VO2 films will be superior to that of VO2 thin films or PcNi thin films. PMID:18306765

  7. Excited state dynamics of nanocrystalline VO2 with white light continuum time resolved spectroscopy

    Science.gov (United States)

    Kürüm, Ula?; Yaglioglu, H. Gul; Küçüköz, Betül; Oksuzoglu, R. Mustafa; Y?ld?r?m, Mustafa; Ya?c?, A. Murat; Pekdemir, Sami; Elmali, Ayhan

    2014-12-01

    In an attempt to use ultrafast pump probe spectroscopy technique with white light continuum to reveal wavelength dependent dynamics of VO2, bandgap needs to be opened. Therefore, nanostructured amorphous and crystalline VO2 thin films were prepared with pulsed DC magnetron reactive sputtering. The mean diameters of grains were measured as 22±0.1 nm and 44±0.1 nm for amorphous and crystalline VO2 thin films, respectively. Temperature dependent resistance measurements show that nanocrystalline VO2 thin film exhibit metal insulator phase transition. The films exhibited dual band gaps (2.3 eV, energy non-equilibrium state related to the photo induced phase.

  8. nc-VO2/Al2O3 nanocomposite films prepared by dual target magnetron sputtering

    International Nuclear Information System (INIS)

    A dual target magnetron sputtering system was used to synthesize nanocomposite films with VO2 nanocrystals embedded in Al2O3 matrix. Glancing incidence X-ray diffraction and high-resolution transmission electron microscopy reveal the formation of VO2 nanocrystallites with monoclinic structure. X-ray photoemission analysis confirmed that oxide particles predominantly possess VO2 stoichiometry. Valence band spectra acquired below and above transition temperature demonstrate that embedded VO2 particles exhibit a first-order monoclinic-to-tetragonal phase transition, however the band shape in a metallic state exhibits feature that is not characteristic for bulk material

  9. Ecuaciones alométricas para estimar biomasa y carbono en Quercus magnoliaefolia / Allometric equations for estimating the above-ground biomass and carbon in Quercus magnoliaefolia Née

    Scientific Electronic Library Online (English)

    Jesús D., Gómez-Díaz; Jorge D., Etchevers-Barra; Alejandro I., Monterrosos-Rivas; Julio, Campo-Alvez; Juan A., Tinoco-Rueda.

    2011-08-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish En el ejido El Zapote de la Reserva de la Biosfera "Sierra de Huautla", estado de Morelos, México, se seleccionaron doce árboles de Quercus magnoliaefolia Née y se determinó su biomasa en la parte aérea. El modelo alométrico quedó expresado como: B = 0.0345 * DAP29334 en donde B es la biomasa (kg) y [...] DAP es el diámetro a la altura del pecho (cm), con un coeficiente de determinación (R²= 0.98; P Abstract in english At the El Zapote ejido in the "Sierra de Huautla" Biosphere Reserve in the state of Morelos, Mexico, twelve Quercus magnoliaefolia Née trees were selected and their above-ground biomass determined. The proposed allometric model was expressed as: B = 0.0345 * DBH2.9334, where B is biomass (kg) and DB [...] H is diameter at breast height (cm), with a coefficient of determination (R²= 0.98; PO.001). In addition, above-ground biomass was estimated by a multiple linear regression based on basal area (BA), specific gravity of wood (SGW) and tree height (H). A high proportion of the biomass variation was explained by basal area alone. SGW and H did not significantly increase the accuracy of the models. The average percentage of carbon in Q. magnoliaefolia trees was 47.14 with values of 46.29 % for the bole, 46.83 % for branches and 48.31 % for foliage. The average proportion of the components of the species studied was 62.5 % for the bole, 27.8 % for branches and 9.6 % for foliage.

  10. Método basado en teledetección para estimar la emisión de gases efecto invernadero por quema de biomasa / A remote sensing method to estimate greenhouse gas emissions from biomass burning

    Scientific Electronic Library Online (English)

    Jesús Adolfo, Anaya Acevedo; Emilio, Chuvieco Salinero; Alicia, Palacios-Orueta.

    2011-01-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish La quema de biomasa es una fuente importante de gases efecto invernadero en países en vías de desarrollo. En Colombia, el cambio de uso del suelo, la silvicultura y el sector agropecuario superan el 50% de las emisiones totales de efecto invernadero. El fuego se utiliza con frecuencia como un mecani [...] smo para cambiar el uso del suelo. Los Llanos orientales y la Amazonía colombiana están sometidos todos los años a la quema de biomasa, especialmente entre enero y marzo. Los estudios en la distribución espacial y temporal de las emisiones son importantes de cara a los informes en el ámbito nacional. Este artículo de revisión describe el método para hacer estas estimaciones utilizando teledetección y algunos de los resultados disponibles para Colombia. Abstract in english Biomass burning is a major source of greenhouse gas emissions in developing countries. In Colombia, land use change, forestry and agriculture are responsible for more than 50% of the total greenhouse gas emissions. Fire is commonly used as a mechanism for land use change. In Colombia the Llanos Orie [...] ntales and the Amazonia are subject to biomass burning every year during the dry season, especially from January to March. Studies of the spatial and temporal distribution of emissions are required for emissions report at a national level. The goal of this state of the art article is to describe a method to estimate emissions with a remote sensing approach and to present some of the variables already measured in Colombia.

  11. Gasificación de biomasa residual en el sector floricultor, caso: Oriente Antioqueño / Gasification of waste biomass in the flower industry, case: Eastern Antioquia

    Scientific Electronic Library Online (English)

    Diego Mauricio, Yepes Maya; Farid, Chejne Janna.

    2012-12-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Este artículo presenta los resultados de gasificación de una mezcla de 1/3 de cada especie de biomasa residual del cultivo de pompón, áster y hortensia con vapor de agua como agente gasificante, en un reactor a escala de laboratorio. La biomasa, como materia prima recibió un secado solar antes de in [...] iciar el proceso de gasificación, se realizó también un procedimiento de reducción de tamaño de partícula a fin de obtener geometrías acordes al proceso de gasificación, se caracterizó mediante el análisis próximo y último y se estableció como temperatura de operación del reactor un rango de 700 a 750°C. Como resultado, la composición del gas de síntesis producido fue analizada por cromatografía gaseosa y para el promedio de producción se obtienen: CH4 2,8 - 5%v, CO 9,3 - 22,2%v, H2 30,3 - 46,6%v. Abstract in english This paper presents the results of gasification of a mixture of 1/3 of each kind of residual biomass cultivation pompon, hydrangea and aster with steam as a gasifying agent in a laboratory scale reactor. The biomass feedstock received a solar drying before starting the gasification process, there wa [...] s also a method for particle size reduction to obtain consistent geometries with gasification process, was characterized by proximate and ultimate analysis and established as reactor operating temperature range of 700 to 750°C. As a result, the composition of the produced synthesis gas was analyzed by gas chromatography and the average yield obtained: CH4 2.8 to 5%v, CO 9.3 to 22.2%v, H2 30.3 to 46.6%v.

  12. Direct fabrication of organic carbon coated VO2(B) (VO2(B)-C) core–shell structured nanobelts by one step hydrothermal route and its formation mechanism

    International Nuclear Information System (INIS)

    Highlights: ? VO2(B)-C core–shell nanobelts were synthesized by a one-step hydrothermal route. ? The effect of glucose and reaction time was briefly discussed. ? Glucose played a dual role, namely as a reductant and as a carbon precursor. ? The possible formation mechanism of VO2(B)-C was proposed. - Abstract: Organic carbon coated vanadium dioxide (VO2(B)-C) core–shell structured nanobelts were successfully synthesized using V2O5 and glucose solution as the starting materials by a facile one-step hydrothermal route. The as-obtained core–shell materials were characterized by scanning electron microscope, transmission electron microscopy, X-ray powder diffraction, energy-dispersive X-ray spectrometer, elemental analysis, Fourier transform infrared spectroscopy and Raman measurements. Some parameters, such as, the concentration of glucose and the reaction time, were briefly discussed to disclose the formation process of VO2(B)-C core–shell structured nanobelts. Glucose played a dual role in the hydrothermal process, namely as a reductant to reduce V2O5 to VO2(B), and as a carbon precursor for the organic carbon shell. The proper quantity of glucose (i.g.: 0.27 g) was beneficial for the fabrication of VO2(B)-C. Furthermore, the possible formation mechanism of VO2(B)-C core–shell structured nanobelts was proposed.d.

  13. Comparative study of optical and scintillation properties of YVO4, (Lu0.5Y0.5)VO4, and LuVO4 single crystals

    International Nuclear Information System (INIS)

    Optical and scintillation properties of YVO4, (Lu0.5Y0.5)VO4, and LuVO4 single crystals grown by the Czochralski (CZ) method with RF heating system are compared. All vanadate crystals show high transmittance (?80%) in the 400-900 nm wavelength range. In both photo- and radio-luminescence spectra, intense peak around 400-500 nm, which was ascribed to the transition from triplet state of VO43-, was clearly observed. The main decay time component was about 38 ?s (YVO4), 18 ?s ((Lu0.5Y0.5)VO4), and 17 ?s (LuVO4) under 340 nm excitation. The scintillation light yields of YVO4, (Lu0.5Y0.5)VO4, and LuVO4 crystals (obtained from the 137Cs excited pulse height spectra) were evaluated to be about 11,200, 10,700, and 10,300 ph/MeV, respectively.

  14. Insights into Stabilization of the 99TcVO Core for Synthesis of 99TcVO Compounds

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Donna; Burton-Pye, Benjamin P.; Lukens, Wayne W.; Howell, Robertha C.; Francesconi, Lynn C.

    2014-01-01

    Synthesis of technetium-99 (99Tc; t1/2: 2.1 105 years, max: 253 keV) materials is of importance in studies of the nuclear fuel cycle where Tc is a major fission product (6percent thermal yield from 235U and 239Pu), in understanding radioactive tank waste composition, and in identifying 99mTc compounds for nuclear medicine imaging. One of the most useful synthetic starting materials, (NBu4)TcOCl4, is susceptible to disproportionation in water to form TcO4 and TcIV species, especially TcO2 2H2O. This unwanted reaction is especially problematic when working with ligands bearing hard donor atoms, such as oxygen, where the stability with the soft TcV=O3+ core may be low. Polyoxometalates (POMs) are such ligands. They possess defect sites with four hard oxygen atoms and show low (ca. 108) stability constants with transition metals. Tc complexes of POMs are molecular-level models for Tc metal oxide solid-state materials and can provide information on coordination and redox environments of metal oxides that stabilize low-valent Tc. In order to synthesize pure Tc POM complexes [TcVO(1-P2W17O61)]7 (TcVO-1) and [TcVO(2-P2W17O61)]7 (TcVO-2) from (NBu4)TcOCl4, we have identified strategies that minimize formation of TcIV species and optimize the formation of pure TcV species. The parameters that we consider are the amount of ethylene glycol, which is employed as a transfer ligand to prevent hydrolysis of (NBu4)TcOCl4, and the precipitating agent. The TcIV species that contaminates the non-optimized syntheses is likely a TcIV -oxido-bridged dimer [TcIV-(-O)2-TcIV]. We also employ a novel procedure where the 2 ligand is photoactivated and reduced (in the presence of a sacrificial electron donor) to subsequently reduce TcVIIO4 to an isolatable TcVO-2 product that is remarkably free of TcIV.

  15. Ruminal degradation of aerial biomass and seeds of wild species of Lupinus / Degradación ruminal de semillas y biomasa aérea de especies silvestres de Lupinus

    Scientific Electronic Library Online (English)

    Maricela, Pablo-Pérez; Luz del C, Lagunes-Espinoza; Jesús, Ramos-Juárez; Javier, López-Upton; Emilio M, Aranda-Ibáñez; Luis, Vargas-Villamil.

    2014-04-01

    Full Text Available La degradación ruminal de la materia seca (DMS) y de la proteína cruda (DPC) en biomasa aérea durante la etapa de floración, y en las semillas de L. campestris, L. exaltatus, L. hintonii y L. montanus fue determinada mediante la técnica de la bolsa de nylon, con dos bovinos machos fistulados, en cin [...] co tiempos de incubación (3, 9, 12, 24 y 48 h), incluyendo una muestra de pasta de soya (PS). Los datos obtenidos se analizaron usando PROC MIXED de SAS para medidas repetidas. Los resultados mostraron interacción entre especie y tiempo de incubación para DMS y DPC de la biomasa aérea y semillas. Entre especies de lupino, alta DMS y DPC de las semillas se observó desde las 3 h de incubación. A las 48 h la DMS y DPC no mostró variación significativa entre especies. DMS fluctuó de 94,3 a 96,7% y la DPC de 98,9 a 99,2%. La tasa de degradación de la fracción insoluble de la MS (kd) en semillas de lupino varió de 6,3 a 8,1% h-1; y la fracción soluble (FS) de 42,3 a 57,3%; valor inferior al de PS. La DMS y DPC de la biomasa aérea mostró diferencias estadísticas significativas entre especies a las 48 h de incubación. L. hintonii con la menor DMS (69,6%) y DPC (88,9%). Para la DPC, L. campestris y L. montanus mostraron las menores kd y FS en biomasa aérea (kd de 5,4% h-1 en ambas y 35,4 y 37,2 para FS, respectivamente) y una alta DPC. Se concluye que las semillas y la biomasa aérea de las especies silvestres de lupino presentan alta degradabilidad de la MS y PC desde las 3 h de incubación, mostrando solo diferencias estadísticas significativas entre ellas a las 48 h para la DMS y DPC de la biomasa aérea (BA). L. campestris y L. exaltatus fueron las especies que mostraron la más alta DMS y DPC de la BA y la más baja de las semillas. Abstract in english Ruminal degradation of dry matter (DMD) and crude protein (CPD) for aerial biomass at the flowering stage and for the seeds of L. campestris, L. exaltatus, L. hintonii and L. montanus was determined using the nylon bag technique with two fistulated steers in five incubation times (3, 9, 12, 24 and 4 [...] 8 h), including a sample of soybean paste (SP). The data obtained were analyzed using PROC MIXED of SAS for repeated measures. The results showed interactions between species and incubation time for DMD and CPD. Among species of lupine, a high DMD and CPD of seeds were observed after three hours of incubation. At 48 h, DMD and CPD did not show significant variation between species: DMD ranged from 94.3% to 96.7% and CPD from 98.9 to 99.2%. The degradation rate of the insoluble fraction of the DM (kd) in lupine seeds ranged from 6.3 to 8.1% h-1, while that of the soluble fraction (SF) ranged from 42.3 to 57.3%, lower value that observed in SP. The DMD and CPD of aerial biomass showed statistically significant differences between species at 48 h of incubation. L. hintonii showed the lowest DMD (69.6%) and CPD (88.9%). L. montanus and L. campestris showed a lower SF and kd (kd of 5.4% h-1 in both, and 35.4 and 37.2 for SF, respectively) and high CPD of aerial biomass. It is concluded that the DM and CP of seeds and biomass of wild lupine were highly degradable as of 3 h of incubation. At 48 h, there were statistically significant differences between DMD and CPD of aboveground biomass (AGB). L. campestris and L. exaltatus showed the highest DMD and CPD of AGB and similar DMD and CPD of seeds.

  16. Doping properties of monoclinic BiVO4 studied by first-principles density-functional theory

    Science.gov (United States)

    Yin, Wan-Jian; Wei, Su-Huai; Al-Jassim, Mowafak M.; Turner, John; Yan, Yanfa

    2011-04-01

    The intrinsic and extrinsic doping properties of BiVO4, i.e., the formation energies and transition energy levels of defects and impurities, have been studied systematically by first-principles density-functional theory. We find that for doping caused by intrinsic defects, O vacancies are shallow donors and Bi vacancies are shallow acceptors. However, these defects compensate each other and can only lead to moderate n-type and p-type conductivities at Bi-rich and O-rich growth conditions, respectively. To obtain BiVO4 with high n-type and p-type conductivities, which are required for forming Ohmic contacts, extrinsic doping using foreign impurities is necessary. Our results reveal that Sr, Ca, Na, and K atoms on Bi sites are very shallow acceptors and have rather low formation energies. The calculated Fermi-level pinning positions predict that doping of these impurities under oxygen-rich growth conditions should result in outstanding p-type conductivity. Substitutional Mo and W atoms on V sites are very shallow donors and have very low formation energies. Fermi-level pinning position calculations expect the doping of Mo and W under oxygen-poor growth conditions to produce excellent n-type conductivity. Also discussed is the dependence of formation energies and transition energies of defects on the atomic size and atomic chemical potential trends.

  17. Comparación de un reactor de biomasa suspendida y un reactor de biomasa adherida para la biodegradación de compuestos tóxicos presentes en aguas residuales de refinerías de petróleo / Biodegradation of toxic compounds from oil refinery wastewater: comparison of two batch reactors with suspended and attached biomass

    Scientific Electronic Library Online (English)

    Lizet Marina, NAVA URREGO; Raquel, GASPERÍN SANCHÉZ; Alfonso, DURÁN MORENO.

    2014-02-01

    Full Text Available Esta investigación comprende un estudio de tratamiento de aguas residuales de una refinería utilizando dos rectores biológicos discontinuos secuenciales (SBR, por sus siglas en inglés Sequencing Batch Reactor). El primero de ellos es un reactor de biomasa suspendida y el segundo es un reactor de bio [...] masa adherida, en el cual se utilizaron soportes plásticos tipo Kaldnes K1. Debido a la diversidad y complejidad de las aguas residuales de refinerías, fue necesario aclimatar los microorganismos utilizando la estrategia de eficiencias fijas para garantizar una buena degradación de los compuestos difícilmente biodegradables o recalcitrantes. Los reactores operaron durante 45 días empleando ciclos de 24 h (llenado, tiempo de reacción, sedimentación, vaciado y tiempo muerto). La carga orgánica volumétrica aplicada a los reactores varió entre 0.44 - 0.54 kg DQO/m³ d; las cargas orgánicas superficiales oscilaron entre 1.56 - 1.80 g DQO/m² d para el reactor de biomasa adherida. El desempeño de los reactores discontinuos secuenciales se evaluó mediante las eficiencias de remoción de DQO, COD y fenoles, obteniendo porcentajes de remoción de 75, 73 y 99 % en el reactor de biomasa suspendida, mientras que en el reactor de biomasa adherida se alcanzaron porcentajes de remoción de 77, 81 y 99 %, respectivamente. La concentración de sólidos suspendidos totales en el reactor de biomasa suspendida fue de aproximadamente 2200 mg SST/L mientras que en el reactor de biomasa adherida se registró entre 450 y 560 mg SST/L. La relación SSV/SST se mantuvo entre 0.8 y 1 en ambos reactores. La concentración de biomasa adherida a los soportes osciló entre 3.98 gST/m² y 5.45 gST/m². En cada reactor se realizaron cuatro perfiles para evaluar la capacidad de los microorganismos para degradar el tipo sustrato al que fueron expuestos en un tiempo determinado. En ambos reactores, los perfiles de degradación 1 y 2 mostraron que la máxima remoción de DQO se presentó durante la primera hora de reacción, mientras que para los perfiles 3 y 4 la máxima remoción se alcanzó después de la segunda hora. En el caso de los fenoles, en todos los perfiles se obtuvo una remoción de más del 98 % durante la primera hora de reacción, indicando que en ambos reactores la biomasa fue capaz de degradar los compuestos tóxicos presentes en las aguas desflemadas sin importar el tipo de aglomeración microbiana utilizada. Abstract in english This study deals with the treatment of an oil refinery's wastewater using two sequencing batch reactors. The first one was a suspended biomass reactor and the second was an attached biomass reactor with Kaldnes K1 carriers. Due to the diversity and complexity of the refinery wastewater, it was neces [...] sary to acclimate the microorganisms using fixed efficiency strategy to ensure a good degradation of the poorly biodegradable or recalcitrant compounds. The reactor operated for 45 days using 24 h cycles (filling, reaction time, settle, draw and idle). The volumetric organic loading applied to both reactors ranged between 0.44 and 0.54 kg COD/m³d; the surface loads ranged between 1.56 - 1.80 g COD/m² d for the attached biomass reactor. The performance of the sequencing batch reactors was assessed by the efficiency of COD removal, DOC and phenols content, obtaining final removal percentages of75, 73 and 99 % in the suspended biomass reactor, while the attached biomass reactor reached removal percentages of 77, 81 and 99 %, respectively. The total suspended solids concentration in the reactor suspended biomass was approximately 2200 mg TSS/L while in the attached biomass reactor was between 450 and SST 560 mg/L. The VSS/TSS ratio was 0.8 and 1 for both reactors. The concentrations of biomass attached ranging from 3.98 g/m² to 5.45 g/m². In each reactor were made four profiles for assessing the ability of microorganisms to degrade type substrate to which they were exposed in a given time. In both reactors, degradation profiles 1 and 2 showed that a high COD removal occurred

  18. The DaCHS Multi-protocol VO Server

    Science.gov (United States)

    Demleitner, M.

    2014-05-01

    GAVO's Data Center Helper Suite (DaCHS) is a suite of tools for publishing data to the Virtual Observatory. It implements all major VO protocols (SCS, SIAP, SSAP, TAP, OAI-PMH). The integrated management and ingestion component allow defining metadata, structure, and services once and re-use the definition throughout the publication cycle from initial metadata aquisition to registry record generation. It has been driving GAVO's data center since 2008 and is now deployed in multiple locations around the globe. This poster briefly describes the design of the system as well as a bird's-eye view of data publishing with DaCHS.

  19. Improving Quality of VoIP over WiMAX

    OpenAIRE

    Mohamed, M. A.; Zaki, F. W.; Mosbah, R. H.

    2012-01-01

    Real-time services such as VoIP are becoming popular and are major revenue earners for network service providers. These services are no longer confined to the wired domain and are being extended over wireless networks. Although some of the existing wireless technologies can support some low-bandwidth applications, the bandwidth demands of many multimedia applications exceed the capacity of these technologies. The IEEE 802.16-based WiMAX promises to be one of the wireless access technologies c...

  20. VoIP Steganography and Its Detection - A Survey

    CERN Document Server

    Mazurczyk, Wojciech

    2012-01-01

    Steganography is an ancient art that encompasses various techniques of information hiding, the aim of which is to secret information into a carrier message. Steganographic methods are usually aimed at hiding the very existence of the communication. Due to the rise in popularity of IP telephony, together with the large volume of data and variety of protocols involved, it is currently attracting the attention of the research community as a perfect carrier for steganographic purposes. This paper is a survey of the existing VoIP steganography (steganophony) methods and their countermeasures.

  1. Trapped-hole centers in irradiated Li3VO4

    Science.gov (United States)

    Murata, Takuya; Miki, Toshikatsu

    1993-02-01

    Defects in lithium vanadate (Li3VO4) exposed to x rays were studied by electron spin resonance (ESR). 77 K irradiation produces two types of trapped-hole centers. One is supposed to be carbonate radical CO3-, which is thermally stable even at room temperature. Another, having a hyperfine interaction with a vanadium nucleus (I=7/2, 99.76% natural abundant) is attributable to an intrinsic O- type center with one neighboring vanadium ion. The center is thermally unstable and anneals out around 200 K. In spite of the prominent detection of trapped-hole centers, ESR signals due to trapped-electron centers have not been clearly observed.

  2. Magnetic order and muon motion in VO2

    Science.gov (United States)

    Mengyan, P. W.; Lichti, R. L.; Baker, B. B.; Jayarathna, G.

    2014-12-01

    We report the first transverse, longitudinal and zero field measurements performed on Vanadium Dioxide (VO2) where we find a significant local magnetic field below T = 34.7 ± 0.16 K at the muon site and Mud motion above 340 K. Distinct shifts in the muon relaxation rates and Kubo-Toyabe delta parameters, near the metal to semiconductor and structural transition (TMST ? 340 K), show that ?+SR measurements may provide additional means to further characterize the mechanisms contributing to these transitions that are yet to be understood.

  3. Visible-light driven degradation of ibuprofen using abundant metal-loaded BiVO? photocatalysts.

    Science.gov (United States)

    Bian, Zhao-Yong; Zhu, Ya-Qi; Zhang, Jun-Xiao; Ding, Ai-Zhong; Wang, Hui

    2014-12-01

    An efficient method for the degradation of ibuprofen as an aqueous contaminant was developed under visible-light irradiation with as-prepared bismuth vanadate (BiVO4) catalysts. The metal-loaded catalysts Cu-BiVO4 and Ag-BiVO4 were synthesized using a hydrothermal process and then a wet-impregnation method. All of the materials were fully characterized by X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and BET surface area. The results indicated that all of the prepared samples had monoclinic scheelite structures. In the metal-loaded catalysts, silver existed as a mixture of Ag and Ag2O on the surface of the catalysts. However, copper existed as Cu2O and CuO. Additionally, the band gap values of BiVO4, Ag-BiVO4, and Cu-BiVO4 were 2.38, 2.31, and 2.30eV, respectively. Compared to the BiVO4 catalyst, the metal-loaded BiVO4 catalysts showed superior photocatalytic properties for the degradation of ibuprofen. PMID:25268078

  4. Investigation of VO–Zni native donor complex in MBE grown bulk ZnO

    International Nuclear Information System (INIS)

    In this paper, we have experimentally investigated the theoretical predictions of VO–Zni to be a native donor in ZnO. Intrinsically zinc-rich n-type ZnO thin films having ND ? 6.23 × 1018 cm?3 grown by molecular beam epitaxy on Si (0 0 1) substrate were annealed in oxygen environment at 500–800 °C, keeping a step of 100 °C for 1 h, each. Room temperature Hall measurements demonstrated that free donor (VO–Zni) concentration decreased exponentially and Arrhenius plot yielded activation energy to be 1.2 ± 0.01 eV. This value is in agreement with theoretically reported activation energy of VO–Zni donor complex in ZnO. We argue; this observation can be explained by two-step process: (i) incoming oxygen fills VO of VO–Zni complex leaving behind Zni; (ii) Zni releases its energy and moves to a lower energy state with respect to the conduction band minima and/or occupies an inactive location. Consequently, Zni–VO complex loses its donor role in the lattice. Our experimental data supported theoretical predictions of VO–Zni to be a native donor. Results from photoluminescence spectroscopy carried out on Zn-rich ZnO additionally justify the existence of VO–Zni complex. (paper)

  5. Voltage switching of a VO2 memory metasurface using ionic gel

    International Nuclear Information System (INIS)

    We demonstrate an electrolyte-based voltage tunable vanadium dioxide (VO2) memory metasurface. Large spatial scale, low voltage, non-volatile switching of terahertz (THz) metasurface resonances is achieved through voltage application using an ionic gel to drive the insulator-to-metal transition in an underlying VO2 layer. Positive and negative voltage application can selectively tune the metasurface resonance into the “off” or “on” state by pushing the VO2 into a more conductive or insulating regime respectively. Compared to graphene based control devices, the relatively long saturation time of resonance modification in VO2 based devices suggests that this voltage-induced switching originates primarily from electrochemical effects related to oxygen migration across the electrolyte–VO2 interface.

  6. Selective growth of single phase VO2(A, B, and M) polymorph thin films

    Science.gov (United States)

    Srivastava, Amar; Rotella, Helene; Saha, Surajit; Pal, Banabir; Kalon, Gopinadhan; Mathew, Sinu; Motapothula, Mallikarjuna; Dykas, Michal; Yang, Ping; Okunishi, Eiji; Sarma, D. D.; Venkatesan, T.

    2015-02-01

    We demonstrate the growth of high quality single phase films of VO2(A, B, and M) on SrTiO3 substrate by controlling the vanadium arrival rate (laser frequency) and oxidation of the V atoms. A phase diagram has been developed (oxygen pressure versus laser frequency) for various phases of VO2 and their electronic properties are investigated. VO2(A) phase is insulating VO2(B) phase is semi-metallic, and VO2(M) phase exhibits a metal-insulator transition, corroborated by photo-electron spectroscopic studies. The ability to control the growth of various polymorphs opens up the possibility for novel (hetero)structures promising new device functionalities.

  7. Voltage switching of a VO{sub 2} memory metasurface using ionic gel

    Energy Technology Data Exchange (ETDEWEB)

    Goldflam, M. D.; Liu, M. K.; Chapler, B. C.; Stinson, H. T.; Sternbach, A. J.; McLeod, A. S.; Basov, D. N., E-mail: dbasov@physics.ucsd.edu [Department of Physics, The University of California at San Diego, La Jolla, California 92093 (United States); Zhang, J. D.; Geng, K. [Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Royal, M.; Jokerst, N. M.; Smith, D. R. [Center for Metamaterials and Integrated Plasmonics, Pratt School of Engineering, Duke University, Durham, North Carolina 27708 (United States); Kim, Bong-Jun [Metal-Insulator Transition Creative Research Center, ETRI, Daejeon 305-350 (Korea, Republic of); Averitt, R. D. [Department of Physics, The University of California at San Diego, La Jolla, California 92093 (United States); Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Kim, H-T. [Metal-Insulator Transition Creative Research Center, ETRI, Daejeon 305-350 (Korea, Republic of); School of Advanced Device Technology, University of Science and Technology, Daejeon 305-333 (Korea, Republic of)

    2014-07-28

    We demonstrate an electrolyte-based voltage tunable vanadium dioxide (VO{sub 2}) memory metasurface. Large spatial scale, low voltage, non-volatile switching of terahertz (THz) metasurface resonances is achieved through voltage application using an ionic gel to drive the insulator-to-metal transition in an underlying VO{sub 2} layer. Positive and negative voltage application can selectively tune the metasurface resonance into the “off” or “on” state by pushing the VO{sub 2} into a more conductive or insulating regime respectively. Compared to graphene based control devices, the relatively long saturation time of resonance modification in VO{sub 2} based devices suggests that this voltage-induced switching originates primarily from electrochemical effects related to oxygen migration across the electrolyte–VO{sub 2} interface.

  8. Voltage switching of a VO2 memory metasurface using ionic gel

    Science.gov (United States)

    Goldflam, M. D.; Liu, M. K.; Chapler, B. C.; Stinson, H. T.; Sternbach, A. J.; McLeod, A. S.; Zhang, J. D.; Geng, K.; Royal, M.; Kim, Bong-Jun; Averitt, R. D.; Jokerst, N. M.; Smith, D. R.; Kim, H.-T.; Basov, D. N.

    2014-07-01

    We demonstrate an electrolyte-based voltage tunable vanadium dioxide (VO2) memory metasurface. Large spatial scale, low voltage, non-volatile switching of terahertz (THz) metasurface resonances is achieved through voltage application using an ionic gel to drive the insulator-to-metal transition in an underlying VO2 layer. Positive and negative voltage application can selectively tune the metasurface resonance into the "off" or "on" state by pushing the VO2 into a more conductive or insulating regime respectively. Compared to graphene based control devices, the relatively long saturation time of resonance modification in VO2 based devices suggests that this voltage-induced switching originates primarily from electrochemical effects related to oxygen migration across the electrolyte-VO2 interface.

  9. Adsorption-controlled growth of BiVO4 by molecular-beam epitaxy

    Directory of Open Access Journals (Sweden)

    S. Stoughton

    2013-10-01

    Full Text Available Single-phase epitaxial films of the monoclinic polymorph of BiVO4 were synthesized by reactive molecular-beam epitaxy under adsorption-controlled conditions. The BiVO4 films were grown on (001 yttria-stabilized cubic zirconia (YSZ substrates. Four-circle x-ray diffraction, scanning transmission electron microscopy (STEM, and Raman spectroscopy confirm the epitaxial growth of monoclinic BiVO4 with an atomically abrupt interface and orientation relationship (001BiVO4 ? (001YSZ with [100]BiVO4 ? [100]YSZ. Spectroscopic ellipsometry, STEM electron energy loss spectroscopy (STEM-EELS, and x-ray absorption spectroscopy indicate that the films have a direct band gap of 2.5 ± 0.1 eV.

  10. Self-Assembly and Horizontal Orientation Growth of VO2 Nanowires

    Science.gov (United States)

    Cheng, Chun; Guo, Hua; Amini, Abbas; Liu, Kai; Fu, Deyi; Zou, Jian; Song, Haisheng

    2014-06-01

    Single-crystalline vanadium dioxide (VO2) nanostructures have attracted an intense research interest recently because of their unique single-domain metal-insulator phase transition property. Synthesis of these nanostructures in the past was limited in density, alignment, or single-crystallinity. The assembly of VO2 nanowires (NWs) is desirable for a ``bottom-up'' approach to the engineering of intricate structures using nanoscale building blocks. Here, we report the successful synthesis of horizontally aligned VO2 NWs with a dense growth mode in the [1-100]quartz direction of a polished x-cut quartz surface using a simple vapor transport method. Our strategy of controlled growth of VO2 NWs promisingly paves the way for designing novel metal-insulator transition devices based on VO2 NWs.

  11. Ternary complex formation between VO(IV)-picolinic acid or VO(IV)-6-methylpicolinic acid and small blood serum bioligands.

    Science.gov (United States)

    Kiss, E; Garribba, E; Micera, G; Kiss, T; Sakurai, H

    2000-01-30

    In order to assess the role of the low molecular mass bioligands of blood serum in vanadium binding, a study was made of the interactions of the complexes formed in the VO(IV)-picolinic acid and VO(IV)-6-methylpicolinic acid systems with various low molecular mass constituents of blood serum, such as oxalate, lactate, citrate and phosphate. The speciation of VO(IV) in these ternary systems and also in the binary VO(IV)-picolinic acid and VO(IV)-6-methylpicolinic acid systems was studied by pH-potentiometry at 25 degrees C and at an ionic strength I = 0.2 M (KCl). The binding modes of the complexes formed were determined by spectral (electronic absorption and EPR) methods. Picolinic acid and 6-methylpicolinic acid were found to form mono and bis complexes through the pyridine nitrogen and carboxylate oxygen, but the presence of the methyl group in 6-methylpicolinic acid surprisingly decreases the stability of its complexes significantly. The results obtained on the ternary systems reveal that mixed ligand complex formation is favoured in these systems, especially with citrate, and must therefore be taken into account in the speciation description of VO(IV) in blood serum. PMID:10766332

  12. AstroStat - A VO Tool for Statistical Analysis

    CERN Document Server

    Kembhavi, Ajit K; Kale, Tejas; Jagade, Santosh; Vibhute, Ajay; Garg, Prerak; Vaghmare, Kaustubh; Navelkar, Sharmad; Agrawal, Tushar; Nandrekar, Deoyani; Shaikh, Mohasin

    2015-01-01

    AstroStat is an easy-to-use tool for performing statistical analysis on data. It has been designed to be compatible with Virtual Observatory (VO) standards thus enabling it to become an integral part of the currently available collection of VO tools. A user can load data in a variety of formats into AstroStat and perform various statistical tests using a menu driven interface. Behind the scenes, all analysis is done using the public domain statistical software - R and the output returned is presented in a neatly formatted form to the user. The analyses performable include exploratory tests, visualizations, distribution fitting, correlation & causation, hypothesis testing, multivariate analysis and clustering. The tool is available in two versions with identical interface and features - as a web service that can be run using any standard browser and as an offline application. AstroStat will provide an easy-to-use interface which can allow for both fetching data and performing power statistical analysis on ...

  13. Thermal properties of a Nd:LuVO4 crystal

    International Nuclear Information System (INIS)

    A Nd-doped lutetium orthovanadate Nd:LuVO4 crystal has been grown using a modified Czochralski method. The thermal properties of this crystal have been studied by measuring the thermal expansion, specific heat and thermal diffusivity. The thermal expansion coefficients are ?11=1.7 x 10-6, ?22=1.5 x 10-6 and ?33=9.1 x 10-6/K in the temperature range of 298-573 K along the three respective crystallographic axes. The specific heat is almost linear and increases from 0.442 to 0.498 Jg-1K-1 in the measured temperature range. The thermal diffusivity is anisotropic and decreases with increasing temperature from 295 to 548 K. At room temperature the calculated thermal conductivities ?11 and ?33 are 7.96 and 9.77 Wm-1K-1, respectively. These thermal parameters of Nd:LuVO4 crystal have indicated that it is an excellent candidate laser material. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. VO2 (A): Reinvestigation of crystal structure, phase transition and crystal growth mechanisms

    International Nuclear Information System (INIS)

    Well crystallized VO2 (A) microrods were grown via a single step hydrothermal reaction in the presence of V2O5 and oxalic acid. With the advantage of high crystalline samples, we propose P4/ncc as an appropriate space group at room temperature. From morphological studies, we found that the oriented attachment and layer by layer growth mechanisms are responsible for the formation of VO2 (A) micro rods. The structural and electronic transitions in VO2 (A) are strongly first order in nature, and a marked difference between the structural transition temperatures and electronic transitions temperature was evidenced. The reversible intra- (LTP-A to HTP-A) and irreversible inter- (HTP-A to VO2 (M1)) structural phase transformations were studied by in-situ powder X-ray diffraction. Attempts to increase the size of the VO2 (A) microrods are presented and the possible formation steps for the flower-like morphologies of VO2 (M1) are described. - Graphical abstract: Using a single step and template free hydrothermal synthesis, well crystallized VO2 (A) microrods were prepared and the P4/ncc space group was assigned to the room temperature crystal structure. Reversible and irreversible phase transitions among different VO2 polymorphs were identified and their progressive nature was highlighted. Attempts to increase the microrods size, involving layer by layer formation mechanisms, are presented. - Highlights: • Highly crystallized VO2 (A) microrods were grown via a single step hydrothermal process. • The P4/ncc space group was determined for VO2 (A) at room temperature. • The electronic structure and progressive nature of the structural phase transition were investigated. • A weak coupling between structural and electronic phase transitions was identified. • Different crystallite morphologies were discussed in relation with growth mechanisms

  15. Synthesis and visible-light photocatalytic activity of NdVO{sub 4} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Xu Jing [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Chongqing University of Science and Technology, Chongqing 401331 (China); Hu Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Liu Gaobin [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Liu Hong; Du Guojun [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Zhang Yan [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

    2011-07-28

    Graphical abstract: NdVO{sub 4} nanowires are synthesized by a simple composite molten salt method. The effective light absorption and photodegradation are found. Highlights: > We report the fabrication, characterization and photocatalytic activity of NdVO{sub 4} nanowires synthesized by the composite molten salt method. > The NdVO{sub 4} nanowires show effective light absorption and high catalytic degradation activity to Rhodamine B. > The electron density states of the NdVO{sub 4} were calculated with the Vienna ab initio simulation package, which explains the light absorption and photodegradation properties. - Abstract: NdVO{sub 4} nanowires are synthesized by a simple composite molten salt method. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectrum, energy dispersive spectrometry and UV-vis spectrum are used to characterize the structure, morphology and composition of the sample. The results show that the product is of tetragonal phase NdVO{sub 4} nanowires which are connected together in bases, rooted in one center, with typical diameters of 100 nm and lengths up to 3 {mu}m. The UV-vis spectrum shows that NdVO{sub 4} nanowires have four strong absorption peaks from the UV to near infrared region. The photocatalytic degradation of Rhodamine B (RhB) and methyl orange under visible light irradiation using the NdVO{sub 4} nanowires are also investigated. Excellent catalytic degradation activity of RhB observed suggests possible applications for organic pollutant treatment under visible light irradiation. The electron density states of the NdVO{sub 4} were calculated with the Vienna ab initio simulation package. The results of these simulations were used to form a description of the observed light absorption and photodegradation properties of NdVO{sub 4} nanowires.

  16. Synthesis and visible-light photocatalytic activity of NdVO4 nanowires

    International Nuclear Information System (INIS)

    Graphical abstract: NdVO4 nanowires are synthesized by a simple composite molten salt method. The effective light absorption and photodegradation are found. Highlights: ? We report the fabrication, characterization and photocatalytic activity of NdVO4 nanowires synthesized by the composite molten salt method. ? The NdVO4 nanowires show effective light absorption and high catalytic degradation activity to Rhodamine B. ? The electron density states of the NdVO4 were calculated with the Vienna ab initio simulation package, which explains the light absorption and photodegradation properties. - Abstract: NdVO4 nanowires are synthesized by a simple composite molten salt method. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectrum, energy dispersive spectrometry and UV-vis spectrum are used to characterize the structure, morphology and composition of the sample. The results show that the product is of tetragonal phase NdVO4 nanowires which are connected together in bases, rooted in one center, with typical diameters of 100 nm and lengths up to 3 ?m. The UV-vis spectrum shows that NdVO4 nanowires have four strong absorption peaks from the UV to near infrared region. The photocatalytic degradation of Rhodamine B (RhB) and methyl orange under visible light irradiation using the NdVO4 nanowires are also investigated. Excellent catalytic degradationed. Excellent catalytic degradation activity of RhB observed suggests possible applications for organic pollutant treatment under visible light irradiation. The electron density states of the NdVO4 were calculated with the Vienna ab initio simulation package. The results of these simulations were used to form a description of the observed light absorption and photodegradation properties of NdVO4 nanowires.

  17. Estrategias de crecimiento y distribución de biomasa en Pinus pseudostrobus bajo diferentes condiciones de competencia / Growth strategies and biomass distribution in Pinus pseudostrobus under different conditions of competition

    Scientific Electronic Library Online (English)

    Víctor H., Cambrón Sandoval; Humberto, Suzán Azpiri; J. Jesús, Vargas Hernández; Nahum M., Sánchez Vargas; Cuauhtémoc, Sáenz-Romero.

    2013-03-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish La intensidad de competencia en la que se desarrollan los individuos es un factor importante en la supervivencia, producción de biomasa y estrategia del crecimiento de la planta (arquitectura), características que interaccionan con su genotipo. En el presente estudio se evaluó el efecto de niveles d [...] e competencia en 13 familias juveniles de medios hermanos de Pinus pseudostrobus Lindl., sobre su supervivencia, producción y distribución de biomasa. Se compararon las condiciones: (I) baja densidad (0.25 x 0.12 m) con múltiples familias aleatorizadas (inter-familiar), (II) alta densidad (0.12 x 0.06 m) con grupos inter-familiares, y (III) alta densidad (0.12 x 0.06 m) con parcelas monofamiliares (intra-familiar), establecidas en un ensayo de jardín común bajo un diseño de parcelas divididas con cuatro repeticiones y cuatro individuos por familia. A 10 meses de establecido el ensayo se cosecharon dos repeticiones. Se detectaron diferencias entre condiciones de competencia (P ?0.05) para todas las variables evaluadas de producción, distribución de biomasa, supervivencia y arquitectura de crecimiento. A nivel de familia se identificaron estrategias en el crecimiento de los individuos semejantes a los tres comportamientos clásicos de arquetipos (de aislamiento, de competencia y de cultivo), así como genotipos que pudieron ajustar su crecimiento en función del ambiente de competencia. Los resultados obtenidos reflejan la importancia de la selección de ambientes y de genotipos para aumentar su adaptación y productividad en los programas de mejoramiento. Abstract in english Competition intensity at which individual plants grow is an important factor in their survival, biomass production and architecture; characteristics that interact with their genotype. In this study, we evaluated the effect of different levels of competition in 13 juvenile families of Pinus pseudostr [...] obus Lindl. half-siblings in terms of plant survival, growth and biomass distribution. The conditions compared were (I) randomized multiple families (inter-family) planted at low density (0.25 x 0.12 m), (II) inter-family groups at high density (0.12 x 0.06 m), and (III) single-family parcels (intra-family) at high density (0.12 x 0.06 m), established in a common garden test under a split plot design with four replicates and four plants per replicate. At 10 months of being established, two replicates were harvested. Differences were detected between competitive conditions for all measured variables on production, biomass distribution, survival and growth architecture (P ? 0.05). At family level we identified individual growth strategies which resemble the three classic ideotypes (isolation, competition and crop), as well as genotypes that adjusted their growth depending on the competitive environment. These results reflect the importance of environmental and genotype selection in order to increase adaptation and productivity at breeding programs.

  18. Factores de expansión de biomasa en comunidades forestales templadas del norte de Durango, México / Biomass expansion factors in temperate forest communities of north Durango

    Scientific Electronic Library Online (English)

    Flor María, Silva-Arredondo; José de Jesús, Návar-Cháidez.

    2010-06-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish La biomasa forestal, por lo general, es cuantificada en kilogramos por árbol o en toneladas por hectárea de peso verde o de peso seco. En un bosque es un elemento ambiental clave para calcular los montos de carbono que puedan liberarse a la atmósfera o bien fijarse, cuando estos ecosistemas son mane [...] jados para mitigar los gases de efecto invernadero. El presente trabajo se llevó a cabo en el norte del estado de Durango, México, con el objetivo de estimar la biomasa arbórea aérea (M) y los factores de expansión de biomasa (FEB) mediante ecuaciones alométricas para los diferentes componentes que provienen de inventarios forestales. Los datos de campo y de laboratorio que se registraron fueron peso verde y peso seco de las ramas y del fuste. La estimación de M se realizó mediante dos procedimientos: 1) con ecuaciones alométricas utilizando el diámetro normal como variable independiente y 2) con la ecuación clásica de física que considera el volumen y la densidad básica de la madera. Habiendo calculado M y los volúmenes por hectárea (ERH) de los inventarios forestales convencionales, se obtuvieron los valores de FEB. Los resultados mostraron diferencias en los métodos para conocer M y, por consiguiente los FEB; el primero parece más sensible y ofrece una mejor representación del fenómeno que el segundo. Los FEB son dependientes de la altura promedio del rodal y de la densidad de la madera; los derivados de los datos de inventario, se distribuyen de forma normal. Abstract in english Forest biomass is generally quantified in kilograms of green or dry weight per tree or in tons per area. It is an environmental key element to assess the carbon amounts that can go to the atmosphere or be fixed when these ecosystems are managed to mitigate the greenhouse-effect gases. This research [...] was conducted in northern Mexico in order to assess the biomass components and biomass expansion factors, with the use of alometric component equations and the classical physics equation that uses wood specific gravity applied to forest inventory data. Field and laboratory recorded data consisted on fresh and oven dried weight of stem and branch components. Biomass estimations were conducted following two procedures: 1) using an alometric equation that feeds with normal diameter and 2) employing the wood specific gravity times volume. Once biomass was estimated at the stand level it was divided by stand volume derived from inventory data to calculate the biomass expansion factors. The results showed differences in methods of estimating biomass and therefore in expansion factors as well. Biomass expansion factors are dependent on the mean top height of trees and wood specific gravity. These parameters are normally distributed for the inventory data utilized.

  19. Vplyv herbicídu Gesagard a fungicídu Fundazol na spolo?enstvo streptomycét vo vysokohorskej pôde.

    Czech Academy of Sciences Publication Activity Database

    Selešiová, Z.; Javoreková, S.; Krišt?fek, Václav; Chro?áková, Alica

    2010-01-01

    Ro?. 9, ?. 1 (2010), s. 13-19. ISSN 1336-1120 R&D Projects: GA MŠk LC06066 Grant ostatní: SAV(SK) VEGA 1/0404/09; SAV(SK) KEGA 3/6228/08 Institutional research plan: CEZ:AV0Z60660521 Keywords : pesticides * streptomycetes * grassland Subject RIV: EH - Ecology, Behaviour

  20. REMOCIÓN DE PLOMO Y NÍQUEL EN SOLUCIONES ACUOSAS USANDO BIOMASAS LIGNOCELULÓSICAS: UNA REVISIÓN / REMOVAL OF LEAD AND NICKEL IN AQUEOUS SOLUTIONS USING LIGNOCELLULOSIC BIOMASS: A REVIEW

    Scientific Electronic Library Online (English)

    Edgar, Quiñones; Candelaria, Tejada; Cesar, Arcia; Víctor, Ruiz.

    2013-12-30

    Full Text Available En la presente revisión, se identifican los bioadsorbentes extraídos de biomasas residuales utilizadas en la remoción de dos metales pesados, que presenta una amplia toxicidad para el ambiente: plomo y níquel. Se evalúa la capacidad de remoción de los mismos, destacando aquellos en los que se han ob [...] tenido altos porcentajes de remoción, mostrando la cinética aplicada en estos experimentos. Se encontró, que los bioadsorbentes más usados incluyen residuos de madera, cáscaras de frutos secos, residuos de cereales y cítricos. Para la remoción de plomo (II), el bagazo de caña de azúcar, con una capacidad de remoción de 333mg/g y para el níquel (II), la corteza de Acacia, con una capacidad de remoción de 294,1mg/g, han sido los bioadsorbentes con mayor eficiencia de remoción. Se encuentra que, en la mayoría de los experimentos, la cinética del proceso de adsorción es regida por la ecuación cinética de pseudo-segundo orden. Se recomienda el diseño de plantas piloto para la remoción de iones metálicos con las biomasas que mostraron mayor capacidad de adsorción, con el fin de que estos procesos puedan ser llevados a escala industrial. Abstract in english The present review identifies bioadsorbents, extracted from residual biomass used in the removal of two highly toxic heavy metals in the environment: lead and nickel. The ability of removal was evaluated, highlighting those which showed removal, presenting the kinetics applied in these experiments. [...] The bioadsorbente used include wood waste, nut shells, grain waste and citrus. It was found that for the removal of lead(II), the sugar cane bagasse with a removal capacity of 333mg/g and for nickel (II) acacia bark with a removal capacity of 294.1mg/g, stand out. These bioadsorbents are those reported with efficient removal ability. The kinetics of the adsorption process in most of the revised experiments is governed by the rate equation of pseudo-second order. A design of a pilot plant for removal of metal ions with biomasses with high adsorption capacity is recommended in order that these processes can be carried out in an industrial scale.

  1. Contenido de carbono y nitrógeno de la biomasa microbiana en suelos de La Habana / Microbial biomass carbon and nitrogen content in Havana Soil

    Scientific Electronic Library Online (English)

    Luís A., Gómez-Jorrin; Amalia, Morales-Valdes; Graciela, Dueñas-Vega; Juana María, Dantin-Martínez; Nereida, Chávez-Gonzalez; Maite, Torres-Leblanch.

    2012-06-01

    Full Text Available SciELO Costa Rica | Language: Spanish Abstract in spanish La presente investigación fue diseñada con el objetivo de calcular el carbono (C) y el nitrógeno (N) inmovilizado en la biomasa microbiana de cuatro suelos Ferralíticos Rojos de la Provincia de La Habana, Cuba, empleando la metodología de “fumigación extracción” en el año 2006. Se colectaron muestra [...] s de cuatro sitios (Bainoa, La Salud, Quivicán y Guanajay), los cuales mostraron diferencias en las características físico - químicas, incluyendo diferencias en contenido de materia orgánica entre 2,8 y 5%. La sensibilidad de las metodologías empleadas fue valorada utilizando el error estándar de las medias como parámetro estadístico. Los niveles de C inmovilizados en la biomasa microbiana en los suelos estudiados, variaron entre 289 y 425 ?g/g de suelo y tuvieron una correlación altamente significativa con el contenido de materia orgánica del suelo. Los contenidos de N inmovilizados variaron entre 62 y 90 ?g/g de suelo y se observó también una correlación significativa entre este parámetro y el contenido de nitrógeno total. El error estándar de la media para las determinaciones del C microbiano varió entre 2 y 16 y fueron ligeramente superiores a lo hallado en reportes anteriores; mientras que los errores observados en las determinaciones del N microbiano se mantuvieron entre los rangos considerados adecuados. Finalmente la metodología fue adaptada a las condiciones del laboratorio. Abstract in english This research was carried out to calculate the microbial biomass carbon and nitrogen content in Red Ferralitic Soils from the Havana province, using the “fumigation and extraction” method. For this work soil samples were taken from four different sites (Bainoa, La Salud, Quivicán and Guanajay) with [...] different physicalchemical characteristics, including organic matter content which ranged from 2.8 and 5%. The sensibility of the methods employed was asssessed using the mean standard error as statistical parameter. The C content in soil microbial biomass ranged from 289 and 425 ?g/g of soil (289 - 425 mg/kg of soil) and had it a significant correlation by soil organic matter content. On the other hand, N content in soil microbial biomass ranged from 62 and 90 ?g/g of soil (62-90 mg/kg of soil), and had it a significant correlation by soil nitrogen content. The mean standard error of microbial C determinations ranged from 2 and 16, being slightly superior to previous reports, while the mean standard error of the microbial N determinations were among adequate limits. Finally, this methodology was adapted to laboratory conditions.

  2. Concentración de carbono en la biomasa aérea del matorral espinoso tamaulipeco / Carbon concentration in the above-ground biomass in the tamaulipan thornscrub

    Scientific Electronic Library Online (English)

    José I., Yerena-Yamallel; Javier, Jiménez-Pérez; Oscar A., Aguirre-Calderón; Eduardo J., Treviño-Garza.

    2011-08-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Se determinó la concentración de carbono por unidad de biomasa base peso seco de 10 especies del matorral espinoso tamaulipeco y para cada uno de sus componentes (tallo, ramas, ramillas, hojas y corteza). La concentración de carbono expresado como porcentaje de la biomasa, se hizo con el equipo Soli [...] ds TOC Analyzer, que determina la concentración de carbono en muestras sólidas a través de combustión completa. Mediante un ANAVA no se encontraron diferencias en la concentración promedio de carbono de las especies (P>0.05); esta concentración varió de 44.25 a 47.08 % con una media general de 45.4±1.32 %; Cordia boissieri (44.25±1.52 %) y Acacia farnesiana (44.52±1.37 %) son las especies que resultaron con los valores de concentración de carbono menores, y Forestiera angustifolia (47.08±1.27 %) con el más alto. El componente corteza de Cordia boissieri obtuvo el menor porcentaje de concentración de carbono (39.62±0.70 %), y las hojas de Acacia schaffneri el mayor (50.14±1.21 %); la interacción de ambos factores resultó significativa (P Abstract in english The carbon concentration per unit of biomass (dry weight basis) was determined for 10 species in the Tamaulipan thornscrub and for each of their components (bole, branches, twigs, leaves and bark). Carbon concentration expressed as a percentage of biomass was obtained using a Solids TOC Analyzer, wh [...] ich determines the carbon concentration in solid samples by complete combustion. By ANOVA, no differences were found among the species in average carbon concentration (P>0.05). This concentration ranged from 44.25 to 47.08 % with an overall average of 45.4±1.32 %. Cordia boissieri (44.25±1.52 %) and Acacia farnesiana (44.52±1.37 %) are the species that had the lowest carbon concentration values, while Forestiera angustifolia (47.08±1.27 %) had the highest. The bark component of Cordia boissieri obtained the lowest carbon concentration percentage (39.62±0.70 %), while the leaves of Acacia schaffneri had the highest (50.14±1.21 %). The interaction of both factors was significant (P

  3. Biomasa microbiana y actividad ureasa del suelo en una pradera permanente pastoreada de Chile Soil microbial biomass and urease activity in a grazed permanent pasture from Chile

    Directory of Open Access Journals (Sweden)

    Pedro Antonio Núñez Ramos

    2012-12-01

    Full Text Available En los sistemas de pasturas; la productividad de la pradera puede estar influenciada por el manejo; debido a su impacto sobre los microorganismos del suelo y el reciclaje de nutrientes. El objetivo de este trabajo fue evaluar la biomasa microbiana (BM del suelo asociada al nitrógeno (BMN; carbono (BMC y la actividad ureasa (AU en una pradera permanente del sur de Chile. Entre la primavera de 2005 y el invierno de 2006 fueron evaluados dos sistemas de pastoreo: pastoreo intenso (PI; pastoreo suave (PS y un tratamiento control (C. El diseño fue en bloques al azar con tres repeticiones. En relación a los valores promedios medidos de las variables en pre y post pastoreo; se produjo un incremento en los contenidos de CB en un 21,8 y 8,6% para PI y PS; mientras que en el control fue sólo de 1,9%. Los contenidos de NB también fueron incrementados en un 16 y 19% para PI y PS; respectivamente en comparación con el control (4%. La actividad ureasa aumentó en 13 y 27% para PI y PS; respectivamente en comparación con el control (5%. El pastoreo; produce un flujo más alto de residuos orgánicos en el suelo; lo que estimula la actividad de la biomasa microbiana y; por tanto; aumentó la AU y los contenidos de CB y NB. Esto sugiere que; en los sistemas de pastoreo; se mejora la fertilidad biológica de los suelos y la disponibilidad de nutrientes.In pasture systems, management practices can affect pasture productivity differently due to their impact on soil microorganisms and nutrient cycling. The objective of this study was to evaluate the relationship between soil microbial biomass (MB nitrogen (MBN, carbon (MBC and urease activity (UA in a permanent pasture in southern Chile. Two grazing systems were evaluated between spring 2005 and winter 2006 : heavy grazing (HG, light grazing (LG and a control treatment (C. Treatments were arranged in a randomized block design with three replications. Concerning the average values of the variables measured at the beginning and at the end of grazing, there was an increase in the content of BC of 21.8 and 8.6% for HG and LG, while the control was only 1.9%. BN contents were also increased by 16 and 19% for HG and LG, respectively, compared with the control (4%. The urease activity increased by 13 and 27% for HG and LG, respectively, compared with the control (5%. Grazing produced a higher flow of organic residues in the soil, stimulating microbial biomass and therefore increasing the UA and the BC and BN content. Thus, soil biological fertility and nutrient availability s increase under grazing systems.

  4. Producción diferencial de biomasa en plántulas de Nothofagus pumilio bajo gradientes de luz y humedad del suelo Differential biomass productivity of Nothofagus pumilio seedlings under light and soil moisture gradients

    OpenAIRE

    Maria Vanessa Lencinas; Guillermo Martínez Pastur; Alicia Moretto; Emilce Gallo; Carlos Busso

    2007-01-01

    Las propuestas silviculturales disminuyen la apertura del dosel, estimulando el crecimiento de las plántulas al modificar la disponibilidad de luz y humedad del suelo. La supervivencia dependerá de su adaptación a estas nuevas condiciones ambientales. El objetivo fue evaluar la producción de biomasa de plántulas bajo gradientes de luz y humedad del suelo en condiciones controladas de luz, riego y temperatura. Se emplearon plántulas de 2-3 años en macetas bajo invernáculo, estudiándos...

  5. EVALUACIÓN DEL IMPACTO DE ACTIVIDADES ANTRÓPICAS EN EL ALMACENAMIENTO DE CARBONO EN BIOMASA VEGETAL EN ECOSISTEMAS DE ALTA MONTAÑA DE COLOMBIA / IMPACT ASSESSMENT OF ANTHROPIC ACTIVITIES ON CARBON IN PLANT BIOMASS STORAGE IN COLOMBIAN HIGH SIERRA ANDEAN ECOSYSTEMS

    Scientific Electronic Library Online (English)

    Alba M., Torres G.; Enrique J., Peña S.; Orlando, Zúñiga E.; Julián A., Peña O..

    2012-06-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Se evaluó el impacto, de las actividades antrópicas, sobre el almacenamiento de carbono en la biomasa vegetal, de bosques intervenidos y no intervenidos, mediante parcelas permanentes, en los ecosistemas de páramo y bosque alto andino, en el Parque Nacional Natural Chingaza y en el Parque Nacional N [...] atural Los Nevados, de Colombia. Se midió directamente, el carbono almacenado en biomasa de pastizales de páramo de forma indirecta, en biomasa de bosques, utilizando ecuaciones calibradas (metodología no destructiva) y se modelaron, ecuaciones de regresión estadística para estimar de forma indirecta, la biomasa de arbustos de páramo. Los resultados muestran que, los bosques altos andinos más conservados, tienen el mayor contenido de carbono, el cual se reduce drásticamente, debido a la fragmentación y la tala. Por consiguiente, es muy importante conservar el bosque alto andino, en el estado más natural posible, porque éste, es el bosque que posee, una mayor reserva de carbono. Abstract in english The impact of anthropic activities on carbon storage in plant biomass was evaluated in intervened and non-intervened forests through the establishment of permanent plots in the moor and Andean high forests in the Colombian Chingaza National Natural Park and in the Snow-covered Mountais National Natu [...] ral Park. . Carbon stored in plant biomass was measured directly in moor grasslands. Indirectly it was measured in forest biomass using calibrated equations (non-destructive methodology) and statistical regression equations were modeled to estimate indirectly the moor biomass. The results show that the most preserved high Andean forests have a higher carbon content which can be reduced drastically because of fragmentation and felling. Therefore, it is very important to maintain the high Andean forest in the most natural state possible, because this is the forest with the highest carbon reserve.

  6. DENSIDAD Y BIOMASA DE MACROINVERTEBRADOS ACUÁTICOS DERIVANTES EN UNA QUEBRADA TROPICAL DE MONTAÑA (BOGOTÁ, COLOMBIA) / Density and biomass of drifting aquatic macroinvertebrates in a tropical mountain creek at Bogotá, Colombia

    Scientific Electronic Library Online (English)

    JAVIER, RODRÍGUEZ-BARRIOS; RODULFO, OSPINA-TORRES; JUAN DAVID, GUTIÉRREZ; HERNANDO, OVALLE.

    2007-12-30

    Full Text Available Se estimó la variación en la densidad de deriva de macroinvertebrados acuáticos y su aporte de materia orgánica en términos de biomasa de diferentes estados inmaduros e imagos, en un tramo de una quebrada tropical de montaña ubicada en los cerros orientales de Bogotá - Colombia y durante eventos de [...] altas y bajas precipitaciones. Se colectó un total de 96 taxones de los cuales el más abundante fue Simulium con 194 individuos (abundancia total). La densidad de deriva al igual que el aporte de biomasa de los macroinvertebrados acuáticos, fue mayor durante el período de bajas precipitaciones. Los dípteros (quironómidos) y los ácaros presentaron la mayor densidad de deriva mientras que los tricópteros (Triplectides) aportaron las mayores biomasas a la deriva. En la escala temporal de un día, no se presentaron diferencias en la densidad y la biomasa en la deriva entre el día y la noche. Abstract in english The variation of drift density of aquatic macroinvertebrates and biomass contribution of different immature and imagos stages were estimate on a stream segment of a first order tropical stream in Eastern hills of Bogotá - Colombia, during high and low rainfall periods. A total of 96 taxa were collec [...] ted; Simulium was the most abundant with 194 individuals (total abundance). Drift density and biomass contributions, were greater during the dry period. Dipterans (chironomids) and mites showed the mayor drift density; trichopterans (Triplectides) showed the greater biomasses to the drift. Significant differences in diel drift pattern between the day and the night (K-S=1.86, p=0.002, n=185), but not in biomass contribution in drift, were observed.

  7. Li2O(Na2O)-CoO-V2O5 systems

    International Nuclear Information System (INIS)

    Equilibrium phase composition of the systems: Li2O-CoO-V2O5 and Na2O-CoO-V2O5 at subsolidus temperatures has been studied. Formation of solid solution Li1-xCox/2VO3 (0? x ? 0.20) and binary orthovanadate LiCoVO4 in lithium-containing system is shown. No ternary compounds have been revealed in sodium-containing system. The relevant diagrams of phase ratios are plotted and their triangulation is performed. 18 refs

  8. Variação diurna e resposta da cinética do VO2 de ciclistas durante exercício muito intenso / Diurnal variation and Vo2 kinetic response of cyclists during heavy exercis e

    Scientific Electronic Library Online (English)

    Marcos G., Santana; Sergio, Tufik; Giselle S., Passos; Donald M., Santee; Benedito S., Denadai; Marco T., Mello.

    2008-06-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo do presente estudo foi avaliar a influência da hora do dia nos parâmetros da cinética do consumo de oxigênio de ciclistas durante exercício muito intenso. Nove voluntários do sexo masculino realizaram exercícios de carga constante às 08:00, 13:00 e 18:00 h, em dias diferentes. Estes exerc [...] ícios foram realizados duas vezes em cada visita, com um intervalo de 1 h entre eles. A intensidade usada foi de 75%? (75% da diferença entre o VO2 no limiar de lactato e o VO2max. A amplitude do componente primário do VO2 (2597 ± 273 ml.min-1, 2513 ± 268 ml.min-1 e 2609 ± 370 ml.min-1), a constante de tempo do componente primário do VO2 (19.3 ± 2.5 s, 18.4 ± 3.0 s e 19.7 ± 3.9 s), o componente lento do VO2 (735 ± 81 ml.min-1, 764 ± 99 ml.min-1 e 680 ± 121 ml.min-1) e o tempo de resposta média (51.8 ± 4.2 s, 51.2 ± 4.2 s e 51.4 ± 3.4 s) não apresentaram diferenças significativas entre os diferentes horários do dia (08:00, 13:00 e 18:00 h), assim como os demais parâmetros da cinética do VO2. Estes resultados sugerem que a resposta da cinética do VO2 de ciclistas durante exercício muito intenso (75%?) não é influenciada pela hora do dia. Abstract in english The objective of the present study was to evaluate the influence of the time of day on the parameters of oxygen uptake kinetics of trained cyclists during high intensity exercise. Nine male volunteers repeated bouts at constant loads at 08:00, 13:00 and 18:00 h on different days. These exercise bout [...] s were performed twice on each occasion, with an interval of 1 h between them. The load intensity used was 75%? (75% of the difference between the VO2 at the lactate threshold and the VO2max). The primary VO2 amplitude (2597 ± 273 ml.min-1, 2513 ± 268 ml.min-1 and 2609 ± 370 ml.min-1), the primary VO2 time constant (19.3 ± 2.5 s, 18.4 ± 3.0 s and 19.7 ± 3.9 s), the VO2 slow component (735 ± 81 ml.min-1, 764 ± 99 ml.min-1 and 680 ± 121 ml.min-1) and the mean response time (51.8 ± 4.2 s, 51.2 ± 4.2 s and 51.4 ± 3.4 s) did not present significant differences at the different times (08:00, 13:00 and 18:00 h), neither did the other parameters of the VO2 kinetics. These results suggest that the response of the VO2 kinetics of cyclists exercising at high intensity (75%?) is not influenced by the time of day.

  9. Reduction of [VO2(ma)2]- and [VO2(ema)2]- by ascorbic acid and glutathione: kinetic studies of pro-drugs for the enhancement of insulin action.

    Science.gov (United States)

    Song, Bin; Aebischer, Nicolas; Orvig, Chris

    2002-03-25

    To shed light on the role of V(V) complexes as pro-drugs for their V(IV) analogues, the kinetics of the reduction reactions of [VO2(ma)2]- or [VO2(ema)2]- (Hma = maltol, Hema = ethylmaltol), with ascorbic acid or glutathione, have been studied in aqueous solution by spectrophotometric and magnetic resonance methods. EPR and 51V NMR studies suggested that the vanadium(V) in each complex was reduced to vanadium(IV) during the reactions. All the reactions studied showed first-order kinetics when the concentration of ascorbic acid or glutathione was in large excess and the observed first-order rate constants have a linear relationship with the concentrations of reductant (ascorbic acid or glutathione). Potentiometric results revealed that the most important species in the neutral pH range is [VO2(L)2]- for the V(V) system where L is either ma- or ema-. An acid dependence mechanism was proposed from kinetic studies with varying pH and varying maltol concentration. The good fits of the second order rate constant versus pH or the total concentration of maltol, and the good agreement of the constants obtained between fittings, strongly supported the mechanism. Under the same conditions, the reaction rate of [VO2(ma)2]- with glutathione is about 2000 times slower than that of [VO2(ma)2]- with ascorbic acid, but an acid dependence mechanism can also be used to explain the results for the reduction with glutathione. Replacing the methyl group in maltol with an ethyl group has little influence on the reduction rate with ascorbic acid, and the kinetics are the same no matter whether [VO2(ma)2]- or [VO2(ema)2]- is reduced. PMID:11896702

  10. Controlled synthesis of VO{sub 2}(R), VO{sub 2}(B), and V{sub 2}O{sub 3} vanadium-oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Jhih-Syuan; Weng, Sheng-Feng; Wu, Ming-Cheng; Lee, Chi-Shen, E-mail: chishen@mail.nctu.edu.tw [National Chiao Tung University, Department of Applied Chemistry (China)

    2013-07-15

    Vanadium-oxide nanowires (NWs) V{sub 2}O{sub 5}, VO{sub 2}(R), VO{sub 2}(B), and V{sub 2}O{sub 3} are deposited on a substrate to study their field-emission properties. V{sub 2}O{sub 5} NWs are prepared by thermal evaporation via vapor transport of a vanadium-oxide complex under mild conditions. Films of VO{sub 2} and V{sub 2}O{sub 3} wires are subsequently prepared by reducing V{sub 2}O{sub 5} one-dimensional nanocrystals at 450 Degree-Sign C with hydrogen gas. The composition of the flowing H{sub 2}/Ar mixture and the duration of reduction are utilized to control the formation of VO{sub 2}(R) or VO{sub 2}(B) NWs. The crystallinity and morphology of products as prepared are characterized using several techniques, including powder X-ray diffraction, a scanning electron microscope, and a transmission electron microscope. The field-emission properties of the vanadium-oxide NWs as prepared exhibit a turn-on field of 4.56-7.65 V/{mu}m and an emission current density up to 3.68-8.36 mA/cm{sup 2}. These features indicate that vanadium-oxide NWs have potential FE emitter applications.Graphical AbstractV{sub 2}O{sub 5}, VO{sub 2}(R), VO{sub 2}(B), and V{sub 2}O{sub 3} NWs were synthesized via thermal evaporation and controlled reduction process. Field-emission properties of these NWs exhibited turn-on fields of 4-8 V/{mu}m, an emission current density up to 3.5 mA/cm{sup 2}.

  11. EPR and UV studies of VO2+ ions in potassium D-gluconate monohydrate single crystals

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance (EPR) of VO2+ doped potassium hydrogen D-gluconate single crystals and powder have been examined at room temperature. Single crystal rotations in each of the three mutually orthogonal crystalline planes namely ac, ba and ca indicate two different VO2+ complexes. Each complex is located in different chemical environments, each environment containing two magnetically inequivalent VO2+ sites in distinct orientations occupying substitutional positions in the lattice and showing a very large angular dependence. The powder spectrum also clearly indicates four different VO2+ complexes, confirming the single crystal analysis. Crystalline field around the VO2+ ion is nearly axial. The optical absorption spectrum of VO2+ ions in the crystal lattice is also studied at room temperature. The characteristic spectrum of the VO2+ ions has two absorption bonds. The bond positions are at 17 857 and 11 235 cm-1. Spin Hamiltonian parameters and molecular orbital coefficients are calculated from the EPR and the optical data, and results are discussed.

  12. Synthesis and magnetic property of Eu doped Pb5(VO4)3OH rod bunches

    Science.gov (United States)

    Xu, Jing; Yuan, Jinhai; Fu, Ya; Tian, Mi; Liu, Derong; Wang, Yue

    2012-07-01

    The undoped and Eu3+ doped Pb5(VO4)3OH rod bunches have been synthesized by a simple CHM method at 200 °C. The characterization of the rod bunches with XRD and XPS indicated that Eu3+ ions were incorporated into the Pb5(VO4)3OH lattice. The crystallite size of Pb5(VO4)3OH: Eu3+ rod bunches was smaller than that of pure Pb5(VO4)3OH rod bunches. The UV-visible spectrum showed that the optical band gap of the doped samples was larger than that of undoped samples. The magnetic properties of the undoped and doped Pb5(VO4)3OH rod bunches have been investigated at room temperature. The crystals exhibited room-temperature ferromagnetic behavior with the remanence magnetization (Mr) of 0.000903 and 0.00179 emu/g and coercivity (Hc) of 18.4 and 28.2 Oe for the Pb5(VO4)3OH and Pb5(VO4)3OH: Eu3+ rod bunches, respectively.

  13. Pacing strategy and VO2 kinetics during a 1500-m race.

    Science.gov (United States)

    Hanon, C; Leveque, J-M; Thomas, C; Vivier, L

    2008-03-01

    We investigated the oxygen uptake response (V.O (2)) to a 1500-m test conducted using a competition race strategy. On an outdoor track, eleven middle-distance runners performed a test to determine V.O (2max), velocity associated with V.O (2max) (v-V.O (2max)) and a supramaximal 1500-m running test (each test at least two days apart). V.O (2max) response was measured with the use of a miniaturised telemetric gas exchange system (Cosmed, K4, Roma, Italy). The 1500-m running test was performed at a mean velocity of 107. 6 + 2 % v-V.O (2max). The maximal value of oxygen uptake recorded during the 1500-m test (V.O (2peak)) was reached by subjects at 75.9 + 7.5 s (mean + SD) (i.e., 459 +/- 59 m). The time to reach V.O (2max) (TV.O (2peak)) and the start velocity (200- to 400-m after the onset of the 1500 m) expressed in % v-V.O (2max) were negatively and significantly correlated (p < 0.05), but our results indicate that a fast start does not necessarily induce a good performance. These results suggest that V.O (2max) is reached by all the subjects at the onset of a simulated 1500-m running event and are therefore in contrast with previous results obtained during treadmill running. PMID:17990206

  14. Effects of erythrocyte infusion on VO2max at high altitude

    DEFF Research Database (Denmark)

    Young, Jette Feveile; Sawka, M N

    1996-01-01

    This study investigated whether autologous erythrocyte infusion would ameliorate the decrement in maximal O2 uptake (VO2max) experienced by lowlanders when they ascend to high altitude. VO2max was measured in 16 men (treadmill running) at sea level (SL) and on the 1st (HA1) and 9th (HA9) days of high-altitude (4,300 m) residence. After VO2max was measured at SL, subjects were divided into two matched groups (n = 8). Twenty-four hours before ascent to high altitude, the experimental group received a 700-ml infusion of autologous erythrocytes and saline (42% hematocrit), whereas the control group received only saline. The VO2max of erythrocyte-infused [54 +/- 1 (SE) ml.kg-1.min-1] and control subjects (52 +/- 2 ml.kg-1.min-1) did not differ at SL before infusion. The decrement in VO2max on HA1 did not differ between groups, averaging 26% overall, despite higher (P <0.01) arterial hematocrit, hemoglobin concentration, and arterial O2 content in the erythrocyte-infused subjects. By HA9, there were no longer any differences in hematocrit, hemoglobin concentration, or arterial O2 content between groups. No change in VO2max occurred between HA1 and HA9 for either group. Thus, despite increasing arterial O2-carrying capacity, autologous erythrocyte infusion did not ameliorate the decrement in VO2max at 4,300-m altitude.

  15. Large epitaxial bi-axial strain induces a Mott-like phase transition in VO2

    Science.gov (United States)

    Kittiwatanakul, Salinporn; Wolf, Stuart A.; Lu, Jiwei

    2014-08-01

    The metal insulator transition (MIT) in vanadium dioxide (VO2) has been an important topic for recent years. It has been generally agreed upon that the mechanism of the MIT in bulk VO2 is considered to be a collaborative Mott-Peierls transition, however, the effect of strain on the phase transition is much more complicated. In this study, the effect of the large strain on the properties of VO2 films was investigated. One remarkable result is that highly strained epitaxial VO2 thin films were rutile in the insulating state as well as in the metallic state. These highly strained VO2 films underwent an electronic phase transition without the concomitant Peierls transition. Our results also show that a very large tensile strain along the c-axis of rutile VO2 resulted in a phase transition temperature of ˜433 K, much higher than in any previous report. Our findings elicit that the metal insulator transition in VO2 can be driven by an electronic transition alone, rather the typical coupled electronic-structural transition.

  16. Fabrication and efficient visible light-induced photocatalytic activity of Bi2WO6/BiVO4 heterojunction

    International Nuclear Information System (INIS)

    The Bi2WO6/BiVO4 photocatalyst with heterojunction structure was synthesized. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicated that Bi2WO6 nanoplate was loaded on the BiVO4 surface. UV–vis diffusion absorption spectra (DRS) displayed no obvious difference between the band gap absorption edges of the BiVO4 and Bi2WO6/BiVO4. It was found that the phenol degradation rate with Bi2WO6/BiVO4 was 2.55 times as great as that with the BiVO4 under visible light (? > 400 nm) by the photocatalytic measurements. The enhanced photocatalytic performance of the Bi2WO6/BiVO4 sample was attributed to the improved separation efficiency of photogenerated hole–electron pairs generated by the heterojunction between Bi2WO6 and BiVO4. -- Highlights: ? The Bi2WO6/BiVO4 photocatalyst with heterojunction structure was synthesized. ? Bi2WO6/BiVO4 showed better photocatalytic performance than BiVO4 under visible light. ? The improved separation rate of h+ and e? leaded to the enhanced photocatalytic ability.

  17. Morphology-dependent photocatalytic removal of NO by hierarchical BiVO4 microboats and microspheres under visible light

    International Nuclear Information System (INIS)

    In this study, hierarchical monoclinic BiVO4 three-dimensional (3D) superstructures with two kinds of morphologies, namely BiVO4 microboats and BiVO4 microspheres, have been controllably synthesized by adjusting reaction time in the template-free hydrothermal process using ethylene glycol as solvent. The nucleation, growth, and self-assembly of the BiVO4 superstructures could be readily controlled with reaction time, which brought different morphologies to the final product. The as-prepared BiVO4 superstructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption experimentation, and UV-vis diffuse reflectance spectra (UV-vis DRS). The monoclinic 3D BiVO4 catalysts are composed of two-dimensional (2D) nanoplates which intercross with each other. Nanoplates were firstly formed by aggregation of primary nanocrystallites and then self-assembly converted to microboats and microspheres via the oriented attachment mechanism. The prepared BiVO4 3D catalysts can respond to visible light and their optical and photocatalytic properties are relevant to their morphologies. The BiVO4 microspheres showed superior photocatalytic activity on removal of gaseous NO compared to the BiVO4 microboats. The morphology-dependent photocatalytic property of the BiVO4 superstructures is discussed. This work suggests that the synthesized BiVO4 micropheres are promising photocatalyst for environmental remediation.

  18. Preparation of Co-BiVO4 Photocatalyst and Its Application in the Photocatalytic Oxidative Thiophene

    Directory of Open Access Journals (Sweden)

    GAO Xiao-Ming, FU Feng, WU Yu-Fei, ZHANG Li-Ping, LI Wen-Hong

    2012-10-01

    Full Text Available The Co-BiVO4 photocatalyst was prepared by hydrothermal method and characterized by X-ray diffraction, scanning electron microscope, UV-Vis absorption spectroscope, and low-temperature N2 adsorption. The characterized results indicate that highly crystalline monoclinic scheelite structure of Co-BiVO4 is obtained at pH=7 and the Co dopant does not change the crystal phase of BiVO4. The Co-BiVO4 has a significant red-shift in the absorption band in the visible region, and its absorption intensity increases greatly for the doped catalyst compared with pure BiVO4. Low-temperature N2 adsorption result reveals that the pore size of the Cu-BiVO4(pH=7 mostly distributes at 2.67 nm. The desulfurization ability of Co-BiVO4 was researched by photocatalytic oxidation of thiophene in visible light. The results show that the Co-BiVO4 photocatalysts exhibit higher photocatalytic activities for degradation of thiophene under visible light irradiation. When pH value is 7.0 and the hydrothermal synthesize time is 8 h, the photocatalytic activities reach the maximum. Under the conditions of 150 mL/min air flow, 1.0 mg/L catalyst amount, and visible light irradiation for 3 h in 400 W xenon lamp light, the desulfurization rate by Co-BiVO4 at 600 mg/L initial concentration increases to 86%.

  19. Estimated V(O2)max from the rockport walk test on a nonmotorized curved treadmill.

    Science.gov (United States)

    Seneli, Rhiannon M; Ebersole, Kyle T; O?Connor, Kristian M; Snyder, Ann C

    2013-12-01

    The Rockport Walk Test (RWT) is a 1-mile walk used to estimate the maximal volume of oxygen uptake (V(O2)max). The purpose of this study was to validate the RWT on a nonmotorized curved treadmill (CT). Twenty-three healthy adults (10 females; 19-44 years old) participated. One trial of the RWT was performed on a measured indoor track (RWTO) and another on the CT (RWTC) on different days in randomized order. Heart rate (HR) and completion time were used to calculate V(O2)max using 6 different general and gender specific equations from previous research. Subjects also performed a treadmill graded exercise test (GXT), which was used as the criterion measure for V(O2)max. Completion times and HR between the 2 RWT were compared using dependent t-tests. Estimated V(O2)max values were compared between the RWTC, RWTO, and GXT through repeated measures analysis of variance, Pearson's correlations (r), and Bland-Altman's plots. There was no difference between completion times for the RWTO and RWTC but HRs were significantly higher with RWTC. When the same equation was applied to the RWTO and RWTC, there were no similar results. All V(O2)max estimations were different from observed V(O2)max except for the estimation from the relative general Kline et al. equation on the RWTO. Despite high correlations (r = 0.75-0.91), the RWTC underestimated V(O2)max. The RWTC underestimates V(O2)max but may be beneficial if a new equation were created specifically for the CT. With appropriate equations for the CT, the RWTC would provide an alternate form of V(O2)max testing. PMID:23478472

  20. Effects of high-intensity interval training on the VO2 response during severe exercise.

    Science.gov (United States)

    Duffield, Rob; Edge, Johann; Bishop, David

    2006-06-01

    This study examined the effect of high-intensity interval training on the VO2 response during severe, constant-load exercise. Prior to, and following training, 10 females (V O2 peak 37.4+/-6.0 mL kg-1 min-1) performed a graded exercise test to determine VO2 peak and lactate threshold (LT) and a 6 min cycle test (CT) at the pre-training VO2 peak intensity. Training involved high-intensity intervals (2 min work, 1 min rest) performed 3x week for 8 weeks. Breath-by-breath data from 0 to 6 min during the CT were smoothed using 5s averages and fit to a bi-exponential model starting from 20s. Training resulted in significant improvements in VO2 max (2.34+/-0.37-2.78+/-0.30 L min-1), power at VO2 max (170+/-26-204+/-25 W) and power at LT (113+/-17-136+/-20 W) (ptraining, the VO2 response showed a significant increase in the amplitude of the primary phase (A1) (1396+/-103-1695+/-100 mL min-1; pVO2 (VO2 EE), with no difference (p>0.05) in the time constants of either phase or the amplitude of the slow component (318+/-67-380+/-48 mL; p=0.15). In conjunction, accumulated oxygen deficit (AOD) (43.7+/-9.8-17.2+/-2.8 mL O2 eq kg-1) and anaerobic contribution to the CT (19.4+/-4.4-7.2+/-1.2%) were significantly reduced. In contrast to previous moderate-intensity research, a high-intensity interval training program increased A1 and VO2 EE for the same absolute exercise intensity, decreasing the AOD during a severe-intensity CT. PMID:16690353

  1. Synthesis and photocatalytic performances of BiVO4 by ammonia co-precipitation process

    International Nuclear Information System (INIS)

    This paper reports the preparation and photocatalytic performance of Bismuth vanadate (BiVO4) by a facile and inexpensive approach. An amorphous BiVO4 was first prepared by a co-precipitation process from aqueous solutions of Bi(NO3)3 and NH4VO3 using ammonia. Followed by heating treatment at various temperatures, the amorphous phase converted to crystalline BiVO4 with a structure between monoclinic and tetragonal scheelite. The crystallization of BiVO4 occurred at about 523 K, while the nanocrystalline BiVO4 were formed with a heat-treatment of lower than 673 K. However, when the heat-treatment was carried out at 773 K, the accumulation of nanocrystals to bulk particles was observed. The photocatalytic performances of the materials were investigated by O2 evolution under visible-light, and MB decomposition under solar simulator. The results demonstrated that the crystalline structure is still the vital factor for the activities of both reactions. However, the crystallinity of BiVO4 gives a major influence on the activity of O2 evolution, whereas the surface area, plays an important role for photocatalytic MB decomposition. - Abstract: BiVO4 was prepared by a co-precipitation process using aqueous ammonia solution, followed by heating treatment at various temperatures. The crystalline structure and crystallization process, and tructure and crystallization process, and their influences on photocatalytic O2 evolution and organic pollutants degradation were investigated. It demonstrated that the crystalline structure is still the vital factor for the activities of both reactions. However, the crystallinity of BiVO4 gives a major influence on the activity of O2 evolution, whereas the surface area, plays an important role for photocatalytic MB decomposition. Display Omitted

  2. Spin polarized HSE hybrid functional calculations of VO2

    International Nuclear Information System (INIS)

    We study the rutile (R) and monoclinic (M1) phases of the prototypical compound VO2 by first principles calculations based on density functional theory, employing the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional. Our results show that the HSE lowest-energy solutions for both the low-temperature M1 phase and the high-temperature R phase, which are obtained upon inclusion of spin polarization, are at odds with experimental observations. For the M1 phase the groundstate is (but should not be) magnetic, while the groundstate of the R phase, which is also spin-polarized, is not (but should be) metallic. The energy difference between the low-temperature and high-temperature phases is also in strong discrepancy with the experimental latent heat.

  3. A VO Archive for the DSS-63 Antenna at Robledo

    Science.gov (United States)

    Alacid, J. Manuel; Ruiz, José Enrique; Gutiérrez, Raúl; Rizzo, Ricardo; Verdes-Montenegro, Lourdes; Solano, Enrique; de Dios Santander-Vela, Juan

    In this contribution we describe the development of a Virtual Observatory (VO) Archive for the DSS-63 antenna of the NASA Deep Space Communication Complex in Robledo de Chavela (Madrid). In an initial step the archive includes observations in the K-band (18-26 GHz) of the mentioned antenna with a future extension to other ranges, in particular the Q-band (40-50 GHz) and the Ka-band (32 GHz). A first version of the archive will be available from the LAEFF Scientific Data Centre1 by the end of 2008. This work is the result of a collaboration between the AMIGA group of the IAA-CSIC and the SVO and Radioastronomy groups at LAEFF and forms part of a pioneering initiative to integrate radio astronomical data and services in the Virtual Observatory.

  4. Active terahertz nanoantennas based on VO2 phase transition.

    Science.gov (United States)

    Seo, Minah; Kyoung, Jisoo; Park, Hyeongryeol; Koo, Sukmo; Kim, Hyun-sun; Bernien, Hannes; Kim, Bong Jun; Choe, Jong Ho; Ahn, Yeong Hwan; Kim, Hyun-Tak; Park, Namkyoo; Park, Q-Han; Ahn, Kwangjun; Kim, Dai-sik

    2010-06-01

    Unusual performances of metamaterials such as negative index of refraction, memory effect, and cloaking originate from the resonance features of the metallic composite atom(1-6). Indeed, control of metamaterial properties by changing dielectric environments of thin films below the metallic resonators has been demonstrated(7-11). However, the dynamic control ranges are still limited to less than a factor of 10,(7-11) with the applicable bandwidth defined by the sharp resonance features. Here, we present ultra-broad-band metamaterial thin film with colossal dynamic control range, fulfilling present day research demands. Hybridized with thin VO(2) (vanadium dioxide) (12-18) films, nanoresonator supercell arrays designed for one decade of spectral width in terahertz frequency region show an unprecedented extinction ratio of over 10000 when the underlying thin film experiences a phase transition. Our nanoresonator approach realizes the full potential of the thin film technology for long wavelength applications. PMID:20469898

  5. Zircon to monazite phase transition in CeVO4

    CERN Document Server

    Panchal, V; Santamaria-Perez, D; Errandonea, D; Manjon, F J; Rodriguez-Hernandez, P; Munoz, A; Achary, S N; Tyagi, A K

    2011-01-01

    X-ray diffraction and Raman-scattering measurements on cerium vanadate have been performed up to 12 and 16 GPa, respectively. Experiments reveal that at 5.3 GPa the onset of a pressure-induced irreversible phase transition from the zircon to the monazite structure. Beyond this pressure, diffraction peaks and Raman-active modes of the monazite phase are measured. The zircon to monazite transition in CeVO4 is distinctive among the other rare-earth orthovanadates. We also observed softening of external translational Eg and internal B2g bending modes. We attributed it to mechanical instabilities of zircon phase against the pressure-induced distortion. We additionally report lattice-dynamical and total-energy calculations which are in agreement with the experimental results. Finally, the effect of non-hydrostatic stresses on the structural sequence is studied and the equations of state of different phases are reported.

  6. Secuestro de carbono en la biomasa aérea de un sistema agrosilvopastoril de Cocos nucifera, Leucaena leucocephala Var. Cunningham y Pennisetum purpureum Cuba CT-115

    Directory of Open Access Journals (Sweden)

    J. M. Anguiano

    2013-01-01

    Full Text Available Con el objetivo de estimar el secuestro de carbono en la biomasa aérea de un sistema agrosilvopastoril (sasp compuesto por cocotero (Cocos nucifera, Leucaena leucocephala Var. Cunningham sembrada en alta densidad y Pennisetum purpureum Cuba CT-115, se llevó a cabo un estudio en un suelo con textura franco arcillo- arenosa. Se utilizó un diseño en bloques al azar con arreglo en parcelas divididas con cuatro tratamientos 0, 40, 60 y 80 mil árboles de leucaena ha-1 y tres repeticiones; la evaluación duró desde su establecimiento hasta 340 días de edad. Los resultados muestran diferencia estadística (P<0.001 en el secuestro de carbono con 101.19d, 109.73c, 122.00b y 128.62a t C+ha-1año-1 para los sasp de 0, 40, 60 y 80 mil plantas de leucaena ha-1, respectivamente. El mayor aporte de secuestro de carbono lo realizó el cocotero que aportó del 60 al 80% del total del sasp y existió una relación inversa de secuestro de carbono de la gramínea al incrementar la densidad de la leguminosa. El tratamiento que incorpora la siembra en alta densidad de la leguminosa arbórea logró un mayor secuestro de carbono.

  7. Chapter 35: Describing Data and Data Collections in the VO

    Science.gov (United States)

    Kent, B. R.; Hanisch, R. J.; Williams, R. D.

    The list of numbers: 19.22, 17.23, 18.11, 16.98, and 15.11, is of little intrinsic interest without information about the context in which they appear. For instance, are these daily closing stock prices for your favorite investment, or are they hourly photometric measurements of an increasingly bright quasar? The information needed to define this context is called metadata. Metadata are data about data. Astronomers are familiar with metadata through the headers of FITS files and the names and units associated with columns in a table or database. In the VO, metadata describe the contents of tables, images, and spectra, as well as aggregate collections of data (archives, surveys) and computational services. Moreover, VO metadata are constructed according to rules that avoid ambiguity and make it clear whether, in the example above, the stock prices are in dollars or euros, or the photometry is Johnson V or Sloan g. Organization of data is important in any scientific discipline. Equally crucial are the descriptions of that data: the organization publishing the data, its creator or the person making it available, what instruments were used, units assigned to measurement, calibration status, and data quality assessment. The Virtual Observatory metadata scheme not only applies to datasets, but to resources as well, including data archive facilities, searchable web forms, and online analysis and display tools. Since the scientific output flowing from large datasets depends greatly on how well the data are described, it is important for users to understand the basics of the metadata scheme in order to locate the data that they want and use it correctly. Metadata are the key to data discovery and data and service interoperability in the Virtual Observatory.

  8. Influence of prior exercise on VO2 kinetics subsequent exhaustive rowing performance.

    Science.gov (United States)

    Sousa, Ana; Ribeiro, João; Sousa, Marisa; Vilas-Boas, João Paulo; Fernandes, Ricardo J

    2014-01-01

    Prior exercise has the potential to enhance subsequent performance by accelerating the oxygen uptake (VO2) kinetics. The present study investigated the effects of two different intensities of prior exercise on pulmonary VO2 kinetics and exercise time during subsequent exhaustive rowing exercise. It was hypothesized that in prior heavy, but not prior moderate exercise condition, overall VO2 kinetics would be faster and the VO2 primary amplitude would be higher, leading to longer exercise time at VO2max. Six subjects (mean ± SD; age: 22.9±4.5 yr; height: 181.2±7.1 cm and body mass: 75.5±3.4 kg) completed square-wave transitions to 100% of VO2max from three different conditions: without prior exercise, with prior moderate and heavy exercise. VO2 was measured using a telemetric portable gas analyser (K4b(2), Cosmed, Rome, Italy) and the data were modelled using either mono or double exponential fittings. The use of prior moderate exercise resulted in a faster VO2 pulmonary kinetics response (?1?=?13.41±3.96 s), an improved performance in the time to exhaustion (238.8±50.2 s) and similar blood lactate concentrations ([La(-)]) values (11.8±1.7 mmol.L(-1)) compared to the condition without prior exercise (16.0±5.56 s, 215.3±60.1 s and 10.7±1.2 mmol.L(-1), for ?1, time sustained at VO2max and [La(-)], respectively). Performance of prior heavy exercise, although useful in accelerating the VO2 pulmonary kinetics response during a subsequent time to exhaustion exercise (?1?=?9.18±1.60 s), resulted in a shorter time sustained at VO2max (155.5±46.0 s), while [La(-)] was similar (13.5±1.7 mmol.L(-1)) compared to the other two conditions. Although both prior moderate and heavy exercise resulted in a faster pulmonary VO2 kinetics response, only prior moderate exercise lead to improved rowing performance. PMID:24404156

  9. Epitaxial growth and structural transition of VO2/MgF2(001)

    Science.gov (United States)

    Shibuya, Keisuke; Sawa, Akihito

    2014-01-01

    We fabricated epitaxial VO2 thin films on MgF2(001) substrates by pulsed laser deposition. Epitaxial films were obtained at deposition temperatures below 520 °C, whereas prominent interdiffusion between VO2 and MgF2 was observed at higher temperatures. We found that epitaxial strain controlled by the deposition temperature results in the shift of the phase transition temperature of the VO2 films. The structural phase transition temperature evaluated by means of X-ray diffraction is coincident with the metal-insulator phase transition temperature.

  10. Metal-insulator transitions in TiO2/VO2 superlattices

    Science.gov (United States)

    Shibuya, Keisuke; Kawasaki, Masashi; Tokura, Yoshinori

    2010-11-01

    We have fabricated a series of superlattices composed of V1-xWxO2 ( x=0 or 0.08 with 1+2x d electron per V atom) and TiO2 (no d electron) to investigate the interface and carrier-confinement effects of the metal-insulator phenomena of VO2 . This study was also motivated by the prediction of a half-metallic state with a semi-Dirac point at the TiO2/VO2 interface [V. Pardo and W. E. Pickett, Phys. Rev. Lett. 102, 166803 (2009)10.1103/PhysRevLett.102.166803]. The growth conditions of the superlattices were optimized so that we could reproduce the known electronic states for the constituent compounds in case of the single-layer films, namely, VO2 exhibiting a paramagnetic metal to spin-singlet insulator transition at around room temperature, V0.92W0.08O2 (W:VO2) being metallic down to the lowest temperature, and TiO2 being a wide-gap band insulator. We found no metallic ground state in these superlattices in contradiction with the theoretical prediction. The TiO2/VO2 superlattices always show a resistive transition, corresponding to the metal-insulator transition in the VO2 single layer, at around 300 K for the VO2 -layer thickness varying from 15 monolayers (ML) down to 3 ML. The resistive transition is accompanied with the structural change, consistent with the V-V dimerization in VO2 along c axis, suggesting the robust spin-singlet bond formation as well as the dimeric lattice distortion persistent even at the TiO2/VO2 interface. In the case of TiO2/W:VO2 superlattices, the insulating ground state revives while the metal-insulator transition temperature decreases from 230 to 95 K as the W:VO2 thickness is increased from 10 to 40 ML. These results indicate the persistent competition between the spin-singlet bond formation and the kinetic energy of correlated electrons regulated by the W:VO2 thickness.

  11. VO2 nanorods for efficient performance in thermal fluids and sensors.

    Science.gov (United States)

    Dey, Kajal Kumar; Bhatnagar, Divyanshu; Srivastava, Avanish Kumar; Wan, Meher; Singh, Satyendra; Yadav, Raja Ram; Yadav, Bal Chandra; Deepa, Melepurath

    2015-03-26

    VO2 (B) nanorods with average width ranging between 50-100 nm are synthesized via a hydrothermal method and the post hydrothermal treatment drying temperature is found to be influential in their overall phase and growth morphology evolution. The nanorods with unusually high optical bandgap for a VO2 material are effective in enhancing the thermal performance of ethylene glycol nanofluids over a wide temperature range as is indicated by the temperature dependent thermal conductivity measurements. Humidity and LPG sensors fabricated using the VO2 (B) nanorods bear testament to their efficient sensing performance, which can be partially attributed to the mesoporous nature of the nanorods. PMID:25773921

  12. Prior Knowledge of Trial Number Influences the Incidence of Plateau at VO2max

    Science.gov (United States)

    Gordon, Dan; Caddy, Oliver; Merzbach, Viviane; Gernigon, Marie; Baker, James; Scruton, Adrian; Keiller, Don; Barnes, Richard

    2015-01-01

    The purpose of this study was to assess the VO2max plateau response at VO2max during a series of pre-determined trials. METHODS: Ten male well-trained athletes (age, 23.0 ± 3.2; height, 183.3 ± 5.5 cm; mass 77.5 ± 11.1 Kg; VO2max 66.5 ± 5.0 ml.kg-1,min-1), but who were VO2max testing naïve and with prior-knowledge of trial number completed four incremental tests to volitional exhaustion, separated by ~72-h for the determination of VO2max and gas exchange threshold. Throughout all trials VO2max was recorded on a breath-by-breath basis using a pre-calibrated metabolic cart, using a plateau criterion of ? VO2 ?1.5 ml.kg-1.min-1 over the final 2 consecutive 30 s sampling periods. A significant difference was observed between trial-1 and trial-4 for plateau incidence (p = 0.0285) rising from 20% in trial-1 to a 70% response rate in trial-4. Furthermore a significant difference was observed for VO2dif (difference between criterion value and ? VO2) in trial-1, 1.02 ± 1.69 ml.kg-1.min-1 (p = 0.038), with non-significant differences observed for all other trials, despite a non-significant difference for VO2max across all trials (p > 0.05). Finally, a significant difference was observed for effort perception (RPE) at volitional exhaustion between trial-1 (17.7 ± 1.3) and trial-4 (19.0 ± 1.4) (p = 0.0052). These data indicate that prior-knowledge of trial number can influence the manifestation of the VO2 plateau in a group of well-trained male athletes, thereby suggesting that a form of effort control is established in order to preserve the finite anaerobic capacity. Key points In well-trained athletes the incidence of plateau at VO2max increases in conjunction with an increase in trial number and the associated sensations of pain and fatigue. By informing the participant of the number of trials to be completed a closed-loop condition is developed whereby effort in all trials is compared to a perceptually developed template. Closed-loop condition leads to a sparing of the finite anaerobic capacity during incremental tests when the number of trials to be completed is known. PMID:25729289

  13. VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis

    OpenAIRE

    Bacon, Andrew P.; Carter, Rickey E.; Ogle, Eric A.; Joyner, Michael J.

    2013-01-01

    Endurance exercise training studies frequently show modest changes in VO2max with training and very limited responses in some subjects. By contrast, studies using interval training (IT) or combined IT and continuous training (CT) have reported mean increases in VO2max of up to ?1.0 L · min?1. This raises questions about the role of exercise intensity and the trainability of VO2max. To address this topic we analyzed IT and IT/CT studies published in English from 1965–2012. Inclusion cri...

  14. Thermochromism of metal-doped VO2 films deposited by dual-target sputtering

    Science.gov (United States)

    Jin, Ping; Tazawa, Masato; Yoshimura, Kazuki; Miki, Takeshi; Igarashi, K.; Tanemura, Sakae

    1994-09-01

    Thermochromic VO2 films were prepared by reactive magnetron sputtering under various conditions of substrate temperature, total sputter pressure and oxygen flow ratio and characterized by XRD, RBS, AFM and spectrophotometry. Films with VO2 single phase were formed from a fairly low substrate temperature of 300 degree(s)C by precisely controlling the oxygen flow ratio. The use of vanadium-nucleated substrates significantly improved the crystallinity of VO2. Tungsten doped V1-xWxO2 films with x equals 0 approximately 0.26 were formed by dual-target sputtering and the thermochromism of films was evaluated. The tungsten doping linearly hysteresis loop width.

  15. Estimación de la biomasa en un bosque bajo manejo de Pinus patula Schltdl. et Cham. en Zacualtipán, Hidalgo / Biomass estimation in a managed Pinus patula Schltdl. et Cham. forest at Zacualtipan, Hidalgo state

    Scientific Electronic Library Online (English)

    Consuelo Marisel, Figueroa-Navarro; Gregorio, Ángeles-Pérez; Alejandro, Velázquez-Martínez; Héctor Manuel de los, Santos-Posadas.

    2010-06-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Con el objetivo de estimar la cantidad de biomasa en la vegetación arbórea de bosques manejados de Pinus patula se realizó el presente estudio en el Ejido La Mojonera, en Zacualtipán, Hidalgo, México. Este ejido cuenta con un plan de manejo forestal bajo el sistema silvícola de "Árboles padres". El [...] bosque está dividido en áreas de corta señaladas con la anualidad en la que se ha efectuado la corta de regeneración. Para estimar la biomasa aérea de P. patula se ajustaron ecuaciones simultáneas de regresión tomando en cuenta los diferentes componentes de la estructura de un árbol (fuste, ramas, follaje y corteza). La cantidad de biomasa arbórea del bosque manejado se obtuvo aplicando las ecuaciones generadas y mediante datos de inventario. La biomasa contenida en el arbolado incrementó con una tasa de 6.7 Mg ha-1 en 25 años. El rodal que había sido cortado en 1982 (rodal de mayor edad producto de la corta) presentó una acumulación de biomasa relativamente similar a la contenida en el arbolado de un área que aún no ha sido intervenida (166.6 y 184.03 Mg ha-1, respectivamente). Por tanto, es posible aseverar que los bosques manejados funcionan eficientemente como fijadores y sumideros de carbono, considerando el esquema de manejo que se esté aplicando. Abstract in english This study was carried out to estimate the aboveground biomass in the tree layer of managed Pinus patula forests, at the Ejido La Mojonera, Hidalgo, Mexico. This Ejido has a forest management plan based on the "seed-tree" method as a silvicultural system. The forest is divided into stands identified [...] with the year when the regeneration cutting was applied. To estimate the biomass of P. patula simultaneous regression equations were adjusted taking into account the different structural components of the trees (stem, branches, foliage, and bark). The amount of tree biomass of the managed forest was obtained using the fitted equations and data from a forest inventory. The aboveground biomass in the tree layer increased with a rate of 6.67 Mg ha-1 in 25 years. The stand harvested in 1982 (the oldest stand originated after the regeneration cutting) showed a biomass accumulation relatively similar to that in the natural forest (166.6 and 184.03 Mg ha-1, respectively). According to our results, it is possible to state that managed forests can efficiently fix CO2 from the atmosphere and might become effective carbon sinks.

  16. Effect of Microwave Pre-Processing of Pelletized Biomass on its Gasification and Combustion / Mikrovi?nu Priekšapstr?des Ietekme Uz Granul?tas Biomasas Gazifik?cijas Un Degšanas Procesiem

    Science.gov (United States)

    Barmina, I.; L?ckrasti?a, A.; Valdmanis, J.; Valdmanis, R.; Za?e, M.; Arshanitsa, A.; Telysheva, G.; Solodovnik, V.

    2013-08-01

    To effectively produce clean heat energy from biomass, microwave (mw) pre-processing of its different types - pelletized wood (spruce), herbaceous biomass (reed canary grass) and their mixture (50:50) - was carried out at the 2.45 GHz frequency with different durations of biomass exposure to high-frequency oscillations. To estimate the mw pre-processing effect on the structure, composition and fuel characteristics of biomass, its thermogravimetric (TG), infrared spectroscopy (FTIR) measurements and elemental analysis were made. The pre-processing is shown to enhance the release of moisture and low-calorific volatiles and the partial destruction of biomass constituents (hemicelluloses, cellulose), promoting variations in the elemental composition and heating values of biomass. The field-enhanced variations of biomass characteristics and their influence on its gasification and combustion were studied using an integrated system of a biomass gasifier and a combustor with swirl-enhanced stabilization of the flame reaction zone. The results show that the mw pre-processing of biomass pellets provides a faster weight loss at the gasification, and, therefore, faster ignition and combustion of the activated pellets along with increased output of heat energy at their burnout Veikti kompleksi eksperiment?lie p?t?jumi par mikrovi??u (2,45 GHz) priekšapstr?des ietekmi uz daž?das izcelsmes biomasas granulu (egles, miežabr??a un to mais?jumu 50:50) gazifik?cijas un degšanas procesiem. P?t?jumi apvieno granul?t?s biomasas element?r? sast?va un termogravimetriskos m?r?jumus, k? ar? granul?t?s biomasas gazifik?cijas un degšanas procesu kompleksu izp?ti, apvienojot biomasas svara izmai?u kin?tiskos m?r?jumus ar degšanas zonas temperat?ras, iek?rtas jaudas un degšanas produktu sast?va kin?tiskiem m?r?jumiem. P?t?jumiem izmantota mazas jaudas eksperiment?l? iek?rta (l?dz 2,5 kW), kuru veido integr?ts gazifik?tors un degšanas kamera. P?t?jumu rezult?t? konstat?ts, ka mikrovi??u priekšapstr?de nodrošina intens?v?ku biomasas gazifik?ciju, ?tr?ku gaistošo savienojumu veidošanos, uzliesmošanu un piln?g?ku sadedzin?šanu ar sekojošu saražot?s ?patn?j? siltuma ener?ijas pieaugumu

  17. Variación anual de la biomasa de Nymphoides fallax ornduff (menyanthaceae) en la laguna de Tecocomulco, Hidalgo, México / Seasonal changes of biomass of Nymphoides fallax ornduff (menyanthaceae) in the lagoon of Tecocomulco, Hidalgo, Mexico

    Scientific Electronic Library Online (English)

    Agustín, Quiroz-Flores; Pedro, Ramírez-García; Antonio, Lot-Helgueras.

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Durante un ciclo anual se cuantificó la variación en la estratificación vertical de la biomasa de Nymphoides fallax y se analizaron las variables físicas y químicas del agua y sedimentos de la laguna de Tecocomulco, Hidalgo. La producción anual neta de N. fallax fue de 3 070.1 g PS m². En el mes de [...] junio la biomasa alcanzó su máximo (958.4 g PS m² ). La contribución de biomasa foliar de N. fallax a la proporción total de biomasa representa el 10%, la de peciolos alcanza el 40% y la contribución de biomasa subterránea equivale en ocasiones a más del 50%. El nivel de fósforo en los sedimentos se encuentra por arriba de la cantidad necesaria para sostener la producción vegetal (? 0.04%). Por los resultados obtenidos en este estudio, se puede señalar que en aquellas zonas ribereñas de la laguna en donde los agricultores han construido bordos, se propicia que durante la época de lluvias la columna de agua cambie bruscamente sus dimensiones pasando de 10 cm hasta alcanzar los 75 cm de profundidad y se eleven los niveles de fósforo en agua y sedimentos, lo que a su vez induce que Nymphoides fallax se vea estresada, y en un caso extremo, temporalmente sea sustituida por aquellas especies mejor adaptadas a las nuevas condiciones físicas y químicas del medio. Abstract in english During an annual cycle was quantified the vertical stratification of the biomass of Nymphoides fallax and analyzed the physical and chemical variables of water and sediments in laguna Tecocomulco, Hidalgo. The annual net production of N. fallax was 3 070.1 g DW m². In June, biomass reached its maxim [...] um (958.4 g DW m²). The contribution of foliar biomass of N. fallax to total biomass ratio was 10% that of petioles reaches 40% and the contribution of belowground biomass, sometimes exceeded 50%. The level of phosphorus in sediments was above the amount needed to sustain crop production (? 0.04%). From the results obtained in this study, we concluded that in those coastal areas of the lagoon where farmers have built levees, these propitiated that during the rainy season the water column abruptly changes from 10 cm to 75 cm and raise the levels of phosphorus in waters and sediments, which in turn appear to induce stress on N. fallax stands. After extreme events of these types, this species can be temporarily substituted by other species best adapted to the new physical and chemical environmental conditions.

  18. Producción diferencial de biomasa en plántulas de Nothofagus pumilio bajo gradientes de luz y humedad del suelo / Differential biomass productivity of Nothofagus pumilio seedlings under light and soil moisture gradients

    Scientific Electronic Library Online (English)

    Maria Vanessa, Lencinas; Guillermo, Martínez Pastur; Alicia, Moretto; Emilce, Gallo; Carlos, Busso.

    Full Text Available Las propuestas silviculturales disminuyen la apertura del dosel, estimulando el crecimiento de las plántulas al modificar la disponibilidad de luz y humedad del suelo. La supervivencia dependerá de su adaptación a estas nuevas condiciones ambientales. El objetivo fue evaluar la producción de biomasa [...] de plántulas bajo gradientes de luz y humedad del suelo en condiciones controladas de luz, riego y temperatura. Se emplearon plántulas de 2-3 años en macetas bajo invernáculo, estudiándose tres niveles de luz: 4%-26%-64% de luz natural incidente; y dos niveles de humedad del suelo: 40-60% y 80-100% de capacidad de campo. Mensualmente se evaluaron área foliar y biomasa, de hojas, tallos, raíces gruesas y finas. La biomasa total y compartimentada, el área foliar y sus relaciones variaron entre meses y niveles, de humedad y de luz. Al finalizar la temporada de crecimiento, la biomasa fue mayor en alta luminosidad y menor humedad del suelo (1,58 g planta-1), respecto de alta humedad (0,49 g planta-1). La biomasa aérea fue mayor bajo luminosidad media (0,30 g planta-1 vs. 0,12-0,26 g planta-1), mientras que la subterránea aumentó con la luz (0,20 g planta-1 vs. 0,07-0,16 g planta-1). Las plántulas modificaron su producción de biomasa aérea y/o subterránea según las condiciones hídrico/lumínicas, generando menores relaciones de biomasa y área foliar bajo mayores niveles de luz. Los distintos sistemas silvícolas deben tener en cuenta los cambios que producen sobre ambos factores (luz y humedad del suelo) para maximizar el potencial de crecimiento aéreo y/o subterráneo de la regeneración natural Abstract in english Silvicultural proposals modify the canopy openness to stimulate seedling growth through the changes in light and soil moisture availability. Their survival depends on their adaptation to these new stand conditions. The objective of this study was to evaluate seedling productivity in light and soil m [...] oisture gradients, along one growing season, under light, soil moisture and air temperature controlled conditions. Forest seedlings (2-3 years old) in plastic pots were placed in a greenhouse, where three light levels were assayed: 4%, 26% and 64% of the natural incident light; and two soil moisture levels: 40-60% and 80-100% of field capacity. Foliar area, total and each component biomass (leaves, stems, thin and thick roots), above/belowground biomass rate and foliar area/biomass rate were monthly measured. Total and compartmentalized biomass, foliar area and their rates significantly varied among months, soil moisture and light gradients. Towards the end of the growing season, biomass was higher in high light and low soil moisture (1.58 g plant-1) compared to high soil moisture levels (0.49 g plant-1). Aboveground biomass was significantly higher under medium light treatment (0.30 g plant-1 vs. 0.12-0.26 g plant-1), while belowground biomass increased with light (0.20 g plant-1 vs. 0.07-0.16 g plant-1). Seedlings modified their above- and below-ground biomass according to soil moisture and light conditions, producing lower rates of biomass and foliar area under the higher light treatments. The different silvicultural proposals must consider their influence over both factors (light and soil moisture) to maximize the above- and below-growth potential of the natural regeneration

  19. Variación espacio-temporal de la biomasa de zooplancton en un sistema estuarino del Caribe Occidental durante dos ciclos anuales / Spatio-temporal variation of zooplankton biomass in an estuarine system of the Western Caribbean during two annual cycles

    Scientific Electronic Library Online (English)

    Lourdes, Vásquez-Yeomans; Iván, Castellanos; Eduardo, Suárez-Morales; Rebeca, Gasca.

    2012-08-01

    Full Text Available SciELO Chile | Language: Spanish Abstract in spanish La Bahía de Chetumal, en el Caribe Occidental es considerada uniformemente hiposalina y oligotrófica. Para definir si la biomasa de zooplancton muestra un comportamiento homogéneo en este sistema costero se analizó la variación temporal y espacial de este parámetro (peso húmedo: mg m-3) durante dos [...] ciclos anuales (1996, 1997). Se obtuvieron muestras bimensuales en las épocas de nortes, secas y lluvias. Durante 1996, la biomasa anual promedio (11,56 mg m-3) fue significativamente menor a la de 1997 (16,18 mg m-3). Se observaron biomasas ligeramente mayores durante nortes en ambos años, seguidas por secas y lluvias, lo que sugiere una estacionalidad en el comportamiento de este factor de la comunidad del zooplancton. Las variaciones mensuales también fueron considerables y sugieren que podría haber cambios importantes a escalas menores a la estacional o interanual. Entre el 45 y 51% de la biomasa en 1996 y 1997 se distribuyó en las localidades más externas y salinas de la bahía independientemente de la época. La alta producción primaria que usualmente se asocia a la zona interna de la bahía no se reflejó en la biomasa del zooplancton, lo que se atribuyó a las limitaciones en la distribución local de los herbívoros del zooplancton residente y posiblemente a la hipoxia relacionada con eutrofización local. Las diferencias interanuales, con mayores valores de biomasa, temperaturas y salinidades en 1997, así como la débil estacionalidad de ese año (nortes) podrían estar asociadas con el efecto regional de El Niño 1997-1998. La biomasa de zooplancton en la bahía fue relativamente baja durante todo el año, independientemente de las épocas climáticas, lo que se atribuyó a su baja energía hidrográfica interna, su escasa vegetación acuática y a su aislamiento de la influencia marina. Abstract in english The bay of Chetumal, in the Western Caribbean, is regarded as an uniformly hypohaline and oligotrophic system. In order to define if the zooplankton biomass shows a homogeneous behavior in this coastal system we analyzed the spatio-temporal variation of this parameter (wet weight: mg m-3) during two [...] years (1996, 1997). During 1996, the average annual biomass (11.56 mg m-3) was significantly lower than that recorded during 1997 (16.18 mg m-3). Slightly lower biomass values were observed in northerlies during both years, followed by dry and wet periods, thus suggesting seasonality in the dynamics of this factor in the zooplankton community. Monthly variations were also considerable and suggest that important changes could also be occurring at scales smaller than the seasonal or interannual. Between 45 and 51% of the biomass in 1996 and 1997 was distributed at the outermost and more saline stations of the bay regardless of the season. The high primary production usually related to the inner zone of the bay was not reflected in the zooplankton biomass; this was explained by local distributional restrictions of the resident herbivorous zooplankton and possibly to hypoxia related to local eutrophication. The interannual differences, with higher biomass, temperature, and salinity found in 1997 and also the weak seasonality of that year could be related to the regional effect of El Niño 1997-98. The zooplankton biomass in the bay was relatively low year-round regardless of the season; this was attributed to its low internal hydrographic energy, scarce aquatic vegetation, and to its isolation from the marine influence.

  20. Cuantificación de biomasa y valor energético de renovales de Quercus ilex en condiciones mediterráneas / Quantification of biomass and energetic value of young natural regenerated stands of Quercus ilex under Mediterranean conditions

    Scientific Electronic Library Online (English)

    Harald, Fernández-Puratich; José Vicente, Oliver-Villanueva.

    Full Text Available La biomasa forestal es clave en la política energética de España. Siendo fundamentales sus estrategias nacionales, regionales y locales, los programas de desarrollo de planes de manejo y la cuantificación de biomasa de las especies más importantes. Así, el objetivo de la investigación fue cuantifica [...] r y analizar el valor energético de la biomasa de encina (Quercus ilex subsp. ballota) en condiciones Mediterráneas. Para ello, varias parcelas de regeneración natural fueron seleccionadas en la Comunidad Valenciana (Este de España). Los principales resultados mostraron un volumen y peso promedio por árbol de 0,045 m³ árbol-1 y 0,033 Mg árbol-1 respectivamente. Además, se determinó el factor de forma (0,66). Con una densidad de masa promedio de 3.200 árboles ha-1 la biomasa potencial es de 105,4 Mg ha-1. Con los resultados, se ajustó una función de biomasa fustal relacionada con el diámetro a la altura del pecho y volumen del fuste con alto coeficiente de determinación y bajos errores de estimación. Esta función es predictiva para la cuantificación de biomasa en bosques puros de regeneración natural de encinas del área Mediterránea. En laboratorio se obtuvo un valor energético de biomasa de 17,0 MJ kg-1. Así, el potencial de la energía es de 513 MJ árbol-1 y 1,8 GJ ha-1. Teniendo en cuenta las grandes áreas forestales y los recursos potenciales derivados de desmontes, clareos y tratamientos silvícolas de prevención de incendios, la encina tiene la aptitud para considerarse como materia prima válida para su uso energético (principalmente térmico) en las áreas rurales mediterráneas. Abstract in english Forest biomass is key to Spain's energy policy. National, regional and local strategies, development programs of management plans and biomass and quantification of the most important species are fundamental. The objective of this research was to quantify and to analyze the calorific value of biomass [...] of holm oak (Quercus ilex subsp. ballota) under Mediterranean conditions. To do this, several natural regenerated plots were selected in the Valencian Community (Eastern Spain). The main obtained results show that the average volume and weight per tree are 0.045 m³ tree-1 and 0.033 Mg tree-1 respectively. In addition, the form factor was determined (0.66). With an average stand density of 3,200 trees ha-1, the total potential biomass is 105.4 Mg ha-1. With the results obtained, a function of stem biomass related to the variables DBH (diameter at breast height) and Vf (volume of stem) has been adjusted with significantly high determination level and low estimation errors. This function can be used for the prediction of biomass quantification in natural regenerated holm oak pure stands in the Mediterranean area. Laboratory results show an energetic value of 17.0 MJ kg-1 biomass. Therefore, the total potential energy is 513 MJ tree-1 and 1.8 GJ ha-1. Considering the large forest areas and the potential resources derived from clearings, thinning and fire prevention silvicultural treatments, the holm oak has the aptitude to be considered a valid raw material for energy use (mainly thermal) in Mediterranean rural areas.

  1. Modelos para estimar la biomasa de especies nativas en plantaciones y bosques secundarios en la zona Caribe de Costa Rica Models for biomass estimation in native forest tree plantations and secondary forests in the Costa Rican Caribbean Region

    Directory of Open Access Journals (Sweden)

    William Fonseca G

    2009-01-01

    Full Text Available El uso de los ecosistemas forestales como sumideros y reservorios de carbono es cada día más aceptado. Aún así, la información fidedigna sobre su crecimiento en biomasa y la capacidad de captura y de almacenamiento de CO2 es insuficiente para proponer formas de compensación a los propietarios de bosques. El objetivo de este trabajo fue construir modelos para estimar la biomasa del árbol en plantaciones de Hieronyma alchorneoides, Vochysia guatemalensis y para un grupo de 35 especies en bosque secundario, en la zona Caribe de Costa Rica. En cada plantación se extrajo un árbol de diámetro promedio a la altura del pecho (d y en bosque secundario un árbol de d promedio de la especie de mayor índice de valor de importancia por clase diamétrica. Se utilizó un muestreo destructivo, separando cada componente del árbol y tomando una muestra de campo para determinar la materia seca. Todos los modelos seleccionados tuvieron un R²aj superior al 82,6%. Las especies arbóreas de bosque secundario mostraron R²aj inferiores. El fuste, raíz y biomasa total del árbol mostraron R²aj > 91,3%, y las hojas y ramas, entre 82,6 y 94,1%. El factor de expansión de biomasa en bosque secundario fue de 1,44 y en plantaciones de 1,56. Se estimó que la relación de biomasa radical respecto a biomasa aérea total y biomasa del fuste fue 0,25 y 0,37, respectivamente, en bosques secundarios; 0,26 y 0,39 en V. guatemalensis, y 0,3 y 0,52 en H. alchorneoides.The use of forest ecosystems as carbon sinks is now more accepted. However, credible information about its growth in terms of biomass and its capacity to capture and store CO2 is still insufficient in order to suggest ways by which forest owners should be compensated. The objective for this study was to construct models that allow us to determine tree biomass for native tree plantations of Hieronyma alchorneoides Allemào, Vochysia guatemalensis Donn and a group of 35 species of secondary forests in the Costa Rican Caribbean region. In each plantation the tree with the mean diameter at breast height (d was harvested; in secondary forests the harvested tree corresponded to the mean d tree with the highest Importance Value Index (IVI for each diametric class. Destructive sampling was used, separating each tree component and collecting a field sample in order to determine dry matter content (MS. All selected models had R²aj values above 82.6%. Tree species from secondary forests showed the lowest R²aj values. Stem, roots and total biomass had R²aj values above 91.3%, while leaves and branches had values between 82.6 and 94.1%. Biomass expansion factor (BEF in secondary forest was 1.44 and in forest tree plantations it was 1.56. The radical biomass (Bra relationship to total aboveground biomass (Bat and stem biomass (Bf in secondary forests was 0.25 and 0.37, respectively, 0.26 and 0.39 for V. guatemalensis and 0.3 and 0.52 for H. alchorneoides.

  2. Modelos para estimar la biomasa de especies nativas en plantaciones y bosques secundarios en la zona Caribe de Costa Rica / Models for biomass estimation in native forest tree plantations and secondary forests in the Costa Rican Caribbean Region

    Scientific Electronic Library Online (English)

    William, Fonseca G; Federico, Alice G; José María, Rey B.

    Full Text Available SciELO Chile | Language: Spanish Abstract in spanish El uso de los ecosistemas forestales como sumideros y reservorios de carbono es cada día más aceptado. Aún así, la información fidedigna sobre su crecimiento en biomasa y la capacidad de captura y de almacenamiento de CO2 es insuficiente para proponer formas de compensación a los propietarios de bos [...] ques. El objetivo de este trabajo fue construir modelos para estimar la biomasa del árbol en plantaciones de Hieronyma alchorneoides, Vochysia guatemalensis y para un grupo de 35 especies en bosque secundario, en la zona Caribe de Costa Rica. En cada plantación se extrajo un árbol de diámetro promedio a la altura del pecho (d) y en bosque secundario un árbol de d promedio de la especie de mayor índice de valor de importancia por clase diamétrica. Se utilizó un muestreo destructivo, separando cada componente del árbol y tomando una muestra de campo para determinar la materia seca. Todos los modelos seleccionados tuvieron un R²aj superior al 82,6%. Las especies arbóreas de bosque secundario mostraron R²aj inferiores. El fuste, raíz y biomasa total del árbol mostraron R²aj > 91,3%, y las hojas y ramas, entre 82,6 y 94,1%. El factor de expansión de biomasa en bosque secundario fue de 1,44 y en plantaciones de 1,56. Se estimó que la relación de biomasa radical respecto a biomasa aérea total y biomasa del fuste fue 0,25 y 0,37, respectivamente, en bosques secundarios; 0,26 y 0,39 en V. guatemalensis, y 0,3 y 0,52 en H. alchorneoides. Abstract in english The use of forest ecosystems as carbon sinks is now more accepted. However, credible information about its growth in terms of biomass and its capacity to capture and store CO2 is still insufficient in order to suggest ways by which forest owners should be compensated. The objective for this study wa [...] s to construct models that allow us to determine tree biomass for native tree plantations of Hieronyma alchorneoides Allemào, Vochysia guatemalensis Donn and a group of 35 species of secondary forests in the Costa Rican Caribbean region. In each plantation the tree with the mean diameter at breast height (d) was harvested; in secondary forests the harvested tree corresponded to the mean d tree with the highest Importance Value Index (IVI) for each diametric class. Destructive sampling was used, separating each tree component and collecting a field sample in order to determine dry matter content (MS). All selected models had R²aj values above 82.6%. Tree species from secondary forests showed the lowest R²aj values. Stem, roots and total biomass had R²aj values above 91.3%, while leaves and branches had values between 82.6 and 94.1%. Biomass expansion factor (BEF) in secondary forest was 1.44 and in forest tree plantations it was 1.56. The radical biomass (Bra) relationship to total aboveground biomass (Bat) and stem biomass (Bf) in secondary forests was 0.25 and 0.37, respectively, 0.26 and 0.39 for V. guatemalensis and 0.3 and 0.52 for H. alchorneoides.

  3. Common Methods of Stellar Spectra Analysis and their Support in VO

    Science.gov (United States)

    Škoda, P.

    2008-10-01

    The proper scientific analysis of a large amount of stellar spectra requires certain capabilities of the analysing tool (e.g. precise semi-automatic fitting for normalisation of the continuum or line-list assisted measurement of spectral lines) as well as flexible list-driven datafile handling. While most astronomical legacy packages comprise powerful analysing and data management features allowing rapid processing of quite complex data, current VO tools are lacking support of even basic capabilities commonly used in stellar spectroscopy. Especially the high resolution optical spectroscopy of stars with rapid line profile variations or of those with complicated emission profiles benefits from a number of specific methods unsupported in todays Virtual Observatory (VO) tools and even lacking definition in VO spectral protocols. In our contribution we identify these techniques, describe their possible implementations and finally give a short overview of several VO-compatible tools emphasising their deficiencies and comparing with the capabilities of common legacy packages.

  4. VoIP for Telerehabilitation: A Pilot Usability Study for HIPAA Compliance

    Directory of Open Access Journals (Sweden)

    Briana Ondich

    2012-06-01

    Full Text Available Consumer-based, free Voice and video over the Internet Protocol (VoIP software systems such as Skype and others are used by health care providers to deliver telerehabilitation and other health-related services to clients. Privacy and security applications as well as HIPAA compliance within these protocols have been questioned by practitioners, health information managers, and other healthcare entities. This pilot usability study examined whether four respondents who used the top three, free consumer-based, VoIP software systems perceived these VoIP technologies to be private, secure, and HIPAA compliant;  most did not.  While the pilot study limitations include the number of respondents and systems assessed, the protocol can be applied to future research and replicated for instructional purposes.  Recommendations are provided for VoIP companies, providers, and users. 

  5. Diode-pumped efficient Yb:YGdVO4 thin-disk laser

    International Nuclear Information System (INIS)

    We report for the first time a continuous wave Yb0.06:Y0.32Gd0.62VO4 (Yb:YGdVO4) laser, based on the 2F5/2 – 2F7/2 transition. The free running Yb:YGdVO4 thin-disk laser oscillation takes place at many different wavelengths, covering a wide range of 1037.0 – 1042.2, 1028.4 – 1040.2, and 1021.9 – 1031.2 nm, for transmissions 0.5%, 1.0%, and 2.0%, respectively. As in the case of the 0.2 mm thick a-cut Yb:YGdVO4 the most efficient laser operation was achieved employing the coupler of 0.5%, producing a maximum output power of 2.25 W which gives an optical-to-optical efficiency of 21.2%, the slope efficiency being 37.3%

  6. Size-dependent optical and dielectric properties of BiVO4 nanocrystals

    Science.gov (United States)

    Sarkar, S.; Chattopadhyay, K. K.

    2012-04-01

    Optical and dielectric properties of BiVO4 nanocrystals with different particle sizes have been investigated. BiVO4 nanocrystals with different particle sizes were synthesized through a solid-state reaction method followed by mechanical ball milling for different time durations. The samples were characterized by X-ray diffraction, UV-Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy. Direct and indirect band gap energies were found to vary in the range 4.04-4.16 eV and 3.51-3.67 eV respectively, for different particle sizes. The band gap energies are higher with respect to their values in the bulk BiVO4 due to quantum confinement effects. Dielectric properties of the BiVO4 nanocrystals were investigated and it was found that the dielectric constant increased from 32 to 41 for the reduction of particle size from 29 to 7 nm.

  7. Functional fiber mats with tunable diffuse reflectance composed of electrospun VO2/PVP composite fibers.

    Science.gov (United States)

    Li, Shaotang; Li, Yamei; Qian, Kun; Ji, Shidong; Luo, Hongjie; Gao, Yanfeng; Jin, Ping

    2014-01-01

    Thermochromic VO2 nanoparticles have been dispersed into polyvinyl pyrrolidone (PVP) fibers by electrospinning of a VO2-PVP blend solution. The structure and optical properties of the obtained composite fiber mat were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis) spectrophotometry, and Fourier transform infrared (FT-IR) spectroscopy. The fiber mat revealed two diffuse reflectance states in infrared spectral region at temperatures under and above the phase transition temperature of VO2 and its IR reflectance is smaller in high temperature. The difference of diffuse reflectance between the two states (?Rdif) was obvious to be more than 25% in the wavelengths from 1.5 ?m to 6 ?m. The diffuse reflectance of the fiber mat could be controlled by adjusting the diameter of the fiber or the content of VO2 in the fibers and this particular optical property was explained by a multiple scattering-absorbing process. PMID:24344924

  8. Predictors of VO2Peak in children age 6- to 7-years-old

    DEFF Research Database (Denmark)

    Dencker, Magnus; Hermansen, Bianca

    2011-01-01

    This study investigated the predictors of aerobic fitness (VO2PEAK) in young children on a population-base. Participants were 436 children (229 boys and 207 girls) aged 6.7 ± 0.4 yrs. VO2PEAK was measured during a maximal treadmill exercise test. Physical activity was assessed by accelerometers. Total body fat and total fat free mass were estimated from skinfold measurements. Regression analyses indicated that significant predictors for VO2PEAK per kilogram body mass were total body fat, maximal heart rate, sex, and age. Physical activity explained an additional 4-7%. Further analyses showed the main contributing factors for absolute values of VO2PEAK were fat free mass, maximal heart rate, sex, and age. Physical activity explained an additional 3-6%.

  9. High-temperature behavior of vanadyl pyrophosphate (VO)2P2O7

    International Nuclear Information System (INIS)

    (VO)2P2O7 has been studied at high temperatures by in situ X-ray powder diffraction in an inert atmosphere. Lattice parameters indicate an anisotropic thermal expansion up to Tc=214-bar C, followed by an approximately isotropic expansion up to 490-bar C. It is proposed that Tc is the temperature of a second-order phase transition between the known room temperature form with space group Pca21 and a high-temperature form with space group Pcab. Above 490-bar C a minority phase develops in the sample that was identified as the V3+ containing compound V4(P2O7)3, while the anisotropic expansion along a suggests that stoichiometric (VO)2P2O7 transforms into (VO)2P2O7+x with interstitial oxygen located between the layers. With an onset at 706-bar C all of the (VO)2P2O7 transforms into VPO4

  10. Infrared characteristics of VO{sub 2} thin films for smart window and laser protection applications

    Energy Technology Data Exchange (ETDEWEB)

    Huang Zhangli; Chen Sihai; Lv Chaohong; Huang Ying; Lai Jianjun [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2012-11-05

    Vanadium dioxide (VO{sub 2}) films with a low semiconductor-to-metal transition temperature of 45 Degree-Sign C were fabricated through direct current magnetron sputtering followed by a post-annealing. Atomic force microscopy measurements show that the VO{sub 2} grain size is about one hundred of nanometers. Infrared (IR) characteristic is well investigated by applying a He-Ne laser power intensity measurement, and the result reveals that the VO{sub 2} film exhibits excellent IR switching property. Furthermore, solar smart window and laser protection experiments demonstrate that the obtained VO{sub 2} thin film is a promising material for the application in related fields.

  11. Two-step hydrothermal process for synthesis of F-doped BiVO4 spheres with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Highlights: •F-doped BiVO4 spheres were synthesized by a simple two step hydrothermal process. •F? ions might restrain the recombination of photogenerated electron–hole pairs. •The as-obtained F-doped BiVO4 spheres exhibit higher photocatalytic activity. -- Abstract: F-doped BiVO4 spheres were synthesized by a simple two step hydrothermal process. The effects of F ions on the microstructure and photocatalytic activity of BiVO4 were investigated in detail. The undoped BiVO4 solid spheres with smooth surface are chemically etched by corrosive F? ions, which result in the F-doped BiVO4 spheres with large pores on the surface. The substitution of O2? ions by F? ions could result in the decrease of the BiVO4 lattice parameters, influence the chemical environment surrounding the Bi, V and O elements, cause the red-shifted of the adsorption edge and modify the absorption abilities in visible light region. F-doped BiVO4 spheres exhibited higher photocatalytic activity than undoped BiVO4 under visible light irradiation because an appropriate amount of F? ions introduced into BiVO4 crystal lattice might effectively restrain the recombination of photogenerated electron–hole pairs

  12. Slow component of VO2 kinetics: Mechanistic bases and practical applications

    DEFF Research Database (Denmark)

    Jones, Andrew M; Grassi, Bruno

    2011-01-01

    The V¿O2 slow component, a slowly-developing increase in V¿O2 during constant-work-rate (CWR) exercise performed above the lactate threshold, represents a progressive loss of skeletal muscle contractile efficiency and is associated with the fatigue process. This brief review outlines the current state of knowledge concerning the mechanistic bases of the V¿O2 slow component and describes practical interventions which can attenuate the slow componentand thus enhance exercise tolerance. There is strong evidence that, during CWR exercise, the development of the V¿O2 slow component is associated with the progressive recruitment of additional (type II) muscle fibers that are presumed to have lower efficiency. Recent studies, however, indicate that muscle efficiency is also lowered (resulting in a 'mirror-image'V¿O2 slow component) during fatiguing, high-intensity exercise in which additional fiber recruitment is unlikely or impossible. Therefore, it appears that muscle fatigue underpins the V¿O2 slow component, although the greater fatigue-sensitivity of recruited type II fibers might still play a crucial role in the loss of muscle efficiency in both situations.Several interventions can reduce the magnitude of the V¿O2slow component and these are typically associated with an enhanced exercise tolerance. These include endurance training, inspiratory muscle training, priming exercise, dietary nitrate supplementation, and the inspiration of hyperoxic gas. All of these interventions reduce muscle fatigue development either by improving muscle oxidative capacity and thus metabolic stability and/or by enhancing bulk muscle O2 delivery or local QO2-to- V¿O2 matching. Future honing of these interventions to maximize their impact on the V¿O2slow component might improve sports performance in athletes and exercise tolerance in the elderly or in patient populations.

  13. Size and composition-controlled fabrication of VO2 nanocrystals by terminated cluster growth

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre; Slack, Jonathan

    2013-05-14

    A physical vapor deposition-based route for the fabrication of VO2 nanoparticles is demonstrated, consisting of reactive sputtering and vapor condensation at elevated pressures. The oxidation of vanadium atoms is an efficient heterogeneous nucleation method, leading to high nanoparticle throughtput. Fine control of the nanoparticle size and composition is obtained. Post growth annealing leads to crystalline VO2 nanoparticles with optimum thermocromic and plasmonic properties.

  14. A novel approach for security issues in VoIP networks in Virtualization with IVR

    OpenAIRE

    Kinjal Shah; Satya Prakash Ghrera; Alok Thaker

    2012-01-01

    VoIP (Voice over Internet Protocol) is a growing technology during last decade. It provides the audio, video streaming facility on successful implementation in the network. However, it provides the text transport facility over the network. Due to implementation of it the cost effective solution, it can be developed for the intercommunication among the employees of a prestigious organization. The proposed idea has been implemented on the audio streaming area of the VoIP technology. In the ...

  15. Cardiac output distribution in miniature swine during locomotory exercise to VO/sub 3max/

    International Nuclear Information System (INIS)

    Distribution of cardiac output (CO) was studied in miniature swine (22 +/- 1 kg) during level treadmill exercise up to the speed (17.7 km/hr) that elicited maximal oxygen consumption (VO/sub 2max/) (60 +/- 4 m1/min/kg). COs and tissue blood flows (BFs) were measured with the radiolabelled microsphere technique. CO increased from a preexercise value of 2.1 +/- 0.5 1/min up to 9.9 +/- 0.5 1/min at VO/sub 2max/. In preexercise standing 43% of CO went to skeletal muscle, which comprised 36 +/- 1% of body mass, 42% to viscera (12 +/- 1% mass), 5% to brain, heart, and lungs (2% +/- 0.1% mass), and 10% to skin and skeleton (35 +/- 2% mass). Preexercise could not be considered resting because of the animals' excitability. Skeletal muscle BF increased progressively with speed up to VO/sub 2max/, both in absolute terms and in percent CO. At VO/sub 2max/, 88% of CO went to muscle, 3% to viscera, 8% to brain, heart and lungs, and 1% to skin and skeleton. Thus, at VO/sub 2max/ only 4% of CO went to the inactive tissues, which constituted 47% of body mass. In 2 pigs that ran at speeds above 17 km/hr, total muscle BF leveled off at VO/sub 2max/. These findings demonstrate that muscle BF progressively increases up to VO/sub 2max/, and that VO2 levels off at the same intensity as muscle flow

  16. VoIP: A Corporate Governance Approach to Avoid the Risk of Civil Liability

    OpenAIRE

    Mariana Gerber; Kerry-Lynn Thomson; Tian Gerber

    2013-01-01

    Since the deregulation of Voice over Internet Protocol (VoIP) in 2005, many South African organizations are now attempting to leverage its cost saving and competitive values. However it has been recently cited that VoIP is one of the greatest new risks to business. This risk is cited to increase Information Security insurance premiums in the near future. Due to the dynamic nature of the technology, regulatory and legislative concerns such as lawful interception of communications and privacy m...

  17. Voltage-controlled switching and thermal effects in VO2 nano-gap junctions

    International Nuclear Information System (INIS)

    Voltage-controlled switching in lateral VO2 nano-gap junctions with different gap lengths and thermal properties was investigated. The effect of Joule heating on the phase transition was found to be strongly influenced by the device geometry, the contact material, and the current. Our results indicate that the VO2 phase transition was likely initiated electronically, which was sometimes followed by a secondary thermally induced transition.

  18. Electronic absorption spectra of VO2+ in ammonium oxalate monohydrate crystals

    International Nuclear Information System (INIS)

    The electronic absorption spectra of VO2+ doped (NH4)2C2O4xH2O crystal reveal four bands at 300 K and additional two bands at 77 K. The band at 32050 cm-1 is ascribed to a charge transfer. The results indicate a low site symmetry for VO2+ in the lattice. An attempt is made to interpret the data in terms of available theories. (author)

  19. Performance Study of Objective Speech Quality Measurement for Modern Wireless-VoIP Communications

    OpenAIRE

    Falk, Tiago H.; Wai-Yip Chan

    2009-01-01

    Wireless-VoIP communications introduce perceptual degradations that are not present with traditional VoIP communications. This paper investigates the effects of such degradations on the performance of three state-of-the-art standard objective quality measurement algorithms—PESQ, P.563, and an “extended” E-model. The comparative study suggests that measurement performance is significantly affected by acoustic background noise type and level as well as speech codec and packet ...

  20. Variação diurna e resposta da cinética do VO2 de ciclistas durante exercício muito intenso Diurnal variation and Vo2 kinetic response of cyclists during heavy exercis e

    OpenAIRE

    Santana, Marcos G.; Sergio Tufik; Passos, Giselle S.; Santee, Donald M.; Denadai, Benedito S.; Mello, Marco T.

    2008-01-01

    O objetivo do presente estudo foi avaliar a influência da hora do dia nos parâmetros da cinética do consumo de oxigênio de ciclistas durante exercício muito intenso. Nove voluntários do sexo masculino realizaram exercícios de carga constante às 08:00, 13:00 e 18:00 h, em dias diferentes. Estes exercícios foram realizados duas vezes em cada visita, com um intervalo de 1 h entre eles. A intensidade usada foi de 75%? (75% da diferença entre o VO2 no limiar de lactato e o VO2max. A...

  1. Familial aggregation of VO(2max) response to exercise training: results from the HERITAGE Family Study.

    Science.gov (United States)

    Bouchard, C; An, P; Rice, T; Skinner, J S; Wilmore, J H; Gagnon, J; Pérusse, L; Leon, A S; Rao, D C

    1999-09-01

    The aim of this study was to test the hypothesis that individual differences in the response of maximal O(2) uptake (VO(2max)) to a standardized training program are characterized by familial aggregation. A total of 481 sedentary adult Caucasians from 98 two-generation families was exercise trained for 20 wk and was tested for VO(2max) on a cycle ergometer twice before and twice after the training program. The mean increase in VO(2max) reached approximately 400 ml/min, but there was considerable heterogeneity in responsiveness, with some individuals experiencing little or no gain, whereas others gained >1.0 l/min. An ANOVA revealed that there was 2.5 times more variance between families than within families in the VO(2max) response variance. With the use of a model-fitting procedure, the most parsimonious models yielded a maximal heritability estimate of 47% for the VO(2max) response, which was adjusted for age and sex with a maternal transmission of 28% in one of the models. We conclude that the trainability of VO(2max) is highly familial and includes a significant genetic component. PMID:10484570

  2. Secure Communication and VoIP Threats in Next Generation Networks

    Directory of Open Access Journals (Sweden)

    M. Hossein Ahmadzadegan

    2013-09-01

    Full Text Available VoIP services are among key issues in the Next Generation Network (NGN for the telecommunication domain. This technology is comprised of positive and negative aspects like similar emerging technologies. Nowadays, telecom operators provide call waiting, conference calling, call transfer, caller ID and other VoIP services based on NGN and all IP solution. Thus, VoIP security is now one of the issues over which many debates take place. In this paper we have decided to concentrate on vulnerability categories for VoIP services in NGN. We try to present the common security threats and vulnerabilities of VoIP services. Determining the vulnerabilities and their classification, together with the risks that this system is threatened by clarifies the ways to penetrate this system and enables administrators to solve the problems. The debate on this matter would be misleading without having full recognition of various specifications. In addition, to make the importance of identifying these types of vulnerabilities clear, we will classify the probability threats for VoIP.

  3. On-line Monitoring of VoIP Quality Using IPFIX

    Directory of Open Access Journals (Sweden)

    Petr Matousek

    2014-01-01

    Full Text Available The main goal of VoIP services is to provide a reliable and high-quality voice transmission over packet networks. In order to prove the quality of VoIP transmission, several approaches were designed. In our approach, we are concerned about on-line monitoring of RTP and RTCP traffic. Based on these data, we are able to compute main VoIP quality metrics including jitter, delay, packet loss, and finally R-factor and MOS values. This technique of VoIP quality measuring can be directly incorporated into IPFIX monitoring framework where an IPFIX probe analyses RTP/RTCP packets, computes VoIP quality metrics, and adds these metrics into extended IPFIX flow records. Then, these extended data are stored in a central IPFIX monitoring system called collector where can be used for monitoring purposes. This paper presents a functional implementation of IPFIX plugin for VoIP quality measurement and compares the results with results obtained by other tools.

  4. Research on Channel-Multiplexed Home Intercom System Based on VoIP

    Directory of Open Access Journals (Sweden)

    Shuixiu Li

    2014-01-01

    Full Text Available In this paper, we propose an intelligent channel-multiplexed home intercom system based on Voice over IP (VoIP, which is different from traditional home intercom system. The transmissions of audio and video signal are both supported in the system. According to different functions, the system is mainly divided into two modules: VoIP module and master control module. VoIP module consists of driver, OS Kernel and application layer, which can guarantee multiple tasks to be processed at the same time and ensure the real-time response of system. To save channel resource, Micro Control Unit (MCU is used to realize the  channel-multiplexed function via the communication with VoIP processor. Therefore, to ensure the normal communication between VoIP module and master control module, we define communication command words based on RS232 protocol.The test and application results indicate that our system achieves the goal of channel-multiplexed audio and video transmission based on VoIP, and has high expansibility.

  5. Monoclinic BiVO4 with regular morphologies: Hydrothermal synthesis, characterization and photocatalytic properties

    International Nuclear Information System (INIS)

    Monoclinic bismuth vanadate (BiVO4) samples with regular morphologies were prepared by a facile hydrothermal process with Bi2O3 and NH4VO3 as starting materials. The physical and photophysical properties of the as-prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR), and UV-vis diffuse reflectance spectroscopy (UV-vis). It was found that cuboid-like, square plate-like and flower-like BiVO4 could be readily obtained by tailoring the pH values of the reaction suspensions in the presence of CTAB. Both pH value and CTAB played crucial roles in the morphology evolution of the as-prepared samples. The bandgaps (Eg) of cuboid-like, square plate-like and flower-like BiVO4 were 2.39 eV, 2.40 eV and 2.46 eV, respectively. The photocatalytic performance of the as-prepared BiVO4 was much better than that of P25 for photodegradation of methyl orange under sunlight irradiation. The photocatalytic activities of BiVO4 samples were highly related to their crystallinities and shapes

  6. ENDOR-determined solvation structure of VO2+ in frozen solutions

    International Nuclear Information System (INIS)

    The solvation structure of the vanadyl ion (VO2+) in methanol and in water-methanol mixtures has been investigated by application of /sup 1H/ and 13C electron nuclear double resonance (ENDOR) spectroscopy. The ligand origins of the proton ENDOR resonances have been assigned with use of materials selectively enriched with 2H. The principal hyperfine coupling (hfc) components of both 1H and 13C in solvent molecules coordinated to the VO2+ ion have been determined by analysis of the H0 dependence of the ENDOR spectra. The ENDOR results provide unambiguous evidence that in water-methanol mixtures only VO(H2O)52+ and [VO(H2O)4(CH3OH)]2+ species are formed. In pure methanol the VO(CH3OH)52+ species is observed. The coordination geometries of the VO2+ complexes are deduced from ENDOR estimates of metal-nucleus distances by using computer-based molecular graphics. It is shown on the basis of molecular modeling that the ENDOR-determined metal-nucleus distances are best accounted for by complexes of tetragonal-pyramidal geometry. 29 references, 9 figures, 7 tables

  7. Structural and magnetic properties of quasi-one-dimensional doped LiCuVO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Abhishek [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221 005 (India); Kumari, Poonam; Das, A. [Solid State Physics Division, Bhaba Atomic Research Center, Mumbai (India); Dwivedi, G.D. [Department of Physics, Banaras Hindu University, Varanasi 221 005 (India); Shahi, P.; Shukla, K.K. [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221 005 (India); Ghosh, A.K. [Department of Physics, Banaras Hindu University, Varanasi 221 005 (India); Nigam, A.K. [Department of CMP and MS, Tata Institute of Fundamental Research, Mumbai 400 005 (India); Chattopadhyay, K.K. [Department of Physics, Jadavpur University, Kolkata 700032 (India); Chatterjee, Sandip, E-mail: schatterji.app@iitbhu.ac.in [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221 005 (India)

    2013-12-15

    The Neutron diffraction, X-ray photoemission and Magnetic properties of Zn, Co and Mn-doped LiCuVO{sub 4} were investigated. Both with Zn and Co doping the antiferromagnetic correlation increase. On the other hand Mn-doping induces the short range ferromagnetic ordering. Neutron diffraction study does not show any phase transition down to 5 K i.e., there is no indication of long range magnetic ordering. Neutron diffraction study also indicates that with Zn, Co and Mn doping the V–O lengths are changed. Maximum change in the V–O distances is observed for Mn-doped sample. On the other hand, X-ray photoemission spectroscopic data indicates Mn doping converts some Cu{sup 2+} ions into Cu{sup 3+} ions. - Graphical abstract: LiCuVO{sub 4} is a quasi-one-dimensional spin magnet. It shows antiferromagnetic ordering. It is observed when Mn is doped in the Cu site of LiCuVO{sub 4} a short range ferromagnetic ordering occurs. - Highlights: • LiCuVO{sub 4} is an one-dimensional spin chain system. • Mn ion is doped in Cu site to induce ferromagnetism. • Doping of Mn ion changes the Cu–O–Cu bond angle which in effect induces ferromagnetism.

  8. Impact of thermal expansion of substrates on phase transition temperature of VO2 films

    Science.gov (United States)

    Sakai, Joe; Zaghrioui, Mustapha; Matsushima, Masaaki; Funakubo, Hiroshi; Okimura, Kunio

    2014-09-01

    Non-epitaxial, (010)M1-oriented VO2 thin films were grown on various substrates [amorphous SiO2, Si (001), Al2O3 (0001), and CaF2 (001)] with Pt (111)/SiO2 buffer layers. Phase transition from MoO2-type monoclinic to rutile-type tetragonal structures of these VO2 layers was investigated with temperature-controlled micro-Raman spectroscopy. It was confirmed that substrates with larger thermal expansion coefficient cause larger out-of-plane lattice spacings of both Pt and VO2, and thus lower transition temperatures of VO2 films, as a result of higher in-plane shrinkage during cooling from the deposition temperature. The transition temperatures and aM1/2 lengths, estimated from bM1 lengths, of present samples were compared with previous reports in a strain—temperature phase diagram. The present results fit with previous reports better by assuming that in-plane lattice aspect ratio of VO2 films is not clamped by the substrates but is flexible during the temperature change. Thermal expansion of substrates is an essential parameter to be taken into account when one considers device application of the phase transition properties of VO2 films, especially thick or non-epitaxial.

  9. VoIP over Multiple IEEE 802.11 Wireless LANs

    CERN Document Server

    Chan, A

    2007-01-01

    Prior work indicates that 802.11 is extremely inefficient for VoIP transport. Only 12 and 60 VoIP sessions can be supported in an 802.11b and an 802.11g WLAN, respectively. This paper shows that the bad news does not stop there. When there are multiple WLANs in the vicinity of each other, the already-low VoIP capacity can be further eroded in a significant manner. For example, in a 5-by-5, 25-cell multi-WLAN network, the VoIP capacities for 802.11b and 802.11g are only 1.63 and 10.34 sessions per AP, respectively. This paper investigates several solutions to improve the VoIP capacity. Based on a conflict graph model, we propose a clique-analytical call-admission scheme, which increases the VoIP capacity by 52% and 37% in 802.11b and 802.11g respectively. If all the three orthogonal frequency channels available in 11b and 11g are used, the capacity can be nearly tripled by the call-admission scheme. This paper also proposes for the first time the use of coarse-grained time-division multiple access (CoTDMA) in ...

  10. [Relationships between maximal oxygen uptake (VO2max) and physical activity, blood pressure and serum lipids].

    Science.gov (United States)

    Kishida, T; Inaba, R; Iwata, H

    1997-07-01

    This study was conducted to investigate the relationships between maximal oxygen uptake (VO2max) and physical activity (occupational and leisure time), blood pressure, and serum lipids. The subjects of this study (n = 727) were those who participated in a "health check for 30-year-olds" in the city of Gifu, Japan, during the period from April 1991 to March 1993. Individuals with a medical history and/or undergoing treatment for coronary heart disease (CHD), other heart diseases, hypertension, diabetes mellitus, liver disease, or renal disease were excluded. Finally, 411 males (30 yrs of age) were considered for this study. VO2max was estimated according to the method of Astrand & Rhyming. The results can be summarized as follows: 1. Both occupational and leisure time physical activity were independently related to VO2max. In subjects with light and moderate occupational physical activity, VO2max was affected by leisure time physical activity rather than occupational physical activity, and in those with heavy occupational physical activity, it was affected by both occupational and leisure time physical activity. 2. According to the results of multiple regression analysis, VO2max adjusted for body mass index, smoking, and alcohol was associated significantly with systolic blood pressure (P VO2max can be considered as a factor to decrease the risk of CHD. PMID:9301218

  11. Body fat, abdominal fat and body fat distribution related to VO(2PEAK) in young children

    DEFF Research Database (Denmark)

    Dencker, Magnus; Wollmer, Per

    2011-01-01

    Abstract Objective. Aerobic fitness, defined as maximum oxygen uptake (VO(2PEAK)), and body fat measurements represent two known risk factors for disease. The purpose of this study was to investigate the relationship between VO(2PEAK) and body fat measurements in young children at a population-based level. Methods. Cross-sectional study of 225 children (128 boys and 97 girls) aged 8-11 years, recruited from a population-based cohort. Total lean body mass (LBM), total fat mass (TBF), and abdominal fat mass (AFM) were measured by dual-energy x-ray absorptiometry. Body fat was also calculated as a percentage of body mass (BF%) and body fat distribution as AFM/TBF. VO(2PEAK) was assessed by indirect calorimetry during maximal exercise test. Results. Significant relationships existed between body fat measurements and VO(2PEAK) in both boys and girls, with Pearson correlation coefficients for absolute values of VO(2PEAK) (0.22-0.36, P<0.05), and for VO(2PEAK) scaled by body mass (-0.38 - -0.70, P

  12. Structural and magnetic properties of quasi-one-dimensional doped LiCuVO4

    International Nuclear Information System (INIS)

    The Neutron diffraction, X-ray photoemission and Magnetic properties of Zn, Co and Mn-doped LiCuVO4 were investigated. Both with Zn and Co doping the antiferromagnetic correlation increase. On the other hand Mn-doping induces the short range ferromagnetic ordering. Neutron diffraction study does not show any phase transition down to 5 K i.e., there is no indication of long range magnetic ordering. Neutron diffraction study also indicates that with Zn, Co and Mn doping the V–O lengths are changed. Maximum change in the V–O distances is observed for Mn-doped sample. On the other hand, X-ray photoemission spectroscopic data indicates Mn doping converts some Cu2+ ions into Cu3+ ions. - Graphical abstract: LiCuVO4 is a quasi-one-dimensional spin magnet. It shows antiferromagnetic ordering. It is observed when Mn is doped in the Cu site of LiCuVO4 a short range ferromagnetic ordering occurs. - Highlights: • LiCuVO4 is an one-dimensional spin chain system. • Mn ion is doped in Cu site to induce ferromagnetism. • Doping of Mn ion changes the Cu–O–Cu bond angle which in effect induces ferromagnetism

  13. Effect of variety and cane yield on sugarcane potential trash / Efecto de las variedades y su rendimiento cultural en la biomasa residual potencial

    Scientific Electronic Library Online (English)

    Eduardo R., Romero; Jorge, Scandaliaris; Patricia A., Digonzelli; Luis G., Alonso; Fernanda, Leggio; Juan A., Giardina; Sergio D., Casen; M. Javier, Tonatto; Juan, Fernández de Ullivarri.

    2009-06-30

    Full Text Available SciELO Argentina | Language: English Abstract in spanish La implementación de sistemas productivos con bajo impacto ambiental es una preocupación tanto para la agroindustria como para la sociedad, resultando la producción de azúcar una de las áreas donde la sustentabilidad es un objetivo prioritario y alcanzable. La cosecha en verde de la caña de azúcar a [...] parece como una importante alternativa para conformar sistemas de producción más limpios, prescindiendo de la quema de material vegetal y residuos de cosecha, conservando el suelo y ofreciendo una posibilidad para la generación de energía. Una estimación del potencial de residuos disponible de la caña de azúcar cobra gran relevancia en el momento de definir estrategias de manejo. Se realizó un estudio para determinar la cantidad de biomasa residual disponible en los cañaverales en forma previa (SPT) y posterior (SFT) a la cosecha mecanizada en verde para las principales variedades cultivadas en la provincia de Tucumán (LCP 85-384, TUCCP 77-42, CP 65-357 y RA 87-3). Además, se estudió la relación entre SPT y SFT a fin de validar la precisión de SPT como predictor de SFT en el caso de la cosecha integral en verde. El incremento del SPT estuvo asociado al mayor rendimiento cultural/ha, registrándose valores del 6,9 a 16,0 t/ha de biomasa residual para rendimientos culturales de 32 a 104 t/ha. LCP 85-384 y CP 65-357 produjeron el mayor SPT, mientras que TUCCP 77-42 generó la menor cantidad para niveles similares de rendimiento cultural. La relación SPT/CY disminuyó y el promedio general fue del 16% del rendimiento cultural, aunque su uso para estimar SPT fue limitado, como señalan los bajos coeficientes de determinación. SPT predijo adecuadamente SFT para el caso de la cosecha integral en verde, y el primero puede ser estimado adecuadamente empleando el rendimiento cultural/ha. Abstract in english Low environmental impact production systems are a major concern in agroindustry and society, with food and sugarcane production being one of the areas where sustainability is a high priority. Green cane harvesting emerges as an important alternative for a cleaner production system, since it excludes [...] the burning of residues, conserves soil and insolves the possibility of energy generation. An estimation of potential sugarcane available trash is very important in order to define management strategies. A research was carried out to determine the amount of dry trash available in cane fields before (SPT) and after green cane harvesting (SFT). Also, the relationship between SPT and SFT was studied in order to validate the precision of SPT as an SFT predictor using green cane combine harvesting for the main cultivated varieties in the sugarcane-growing area of Tucumán (LCP 85-384, TUCCP 77-42, CP 65-357 and RA 87-3). An increase in SPT was associated to cane yielding/ha, ranging from 6.9 to 16.0 t/ha of SPT for 32 to 104 t/ha of cane yielding. LCP 85-384 and CP 65-357 produced the highest amount of dry trash before harvest, while TUCCP 77-42 produced the least for similar cane yielding. Simultaneously the DT/CY ratio decreased with a mean value around 16% of cane yield and its use for estimating SPT was limited, as low coefficients of determination highlight. SPT appropriately predicted SFT under green cane combine harvesting conditions and the former one could be estimated using cane yielding/ha.

  14. Efecto de la sequía en la producción de biomasa y grano de frijol Drought effect in bean biomass and grain production

    Directory of Open Access Journals (Sweden)

    Efraín Acosta-Díaz

    2011-04-01

    Full Text Available La sequía intermitente es el factor que más limita la producción de frijol (Phaseolus vulgaris L. bajo temporal en México. El objetivo fue determinar el efecto de la sequía sobre la acumulación de biomasa del vástago y el rendimiento de grano en variedades criollas e introducidas de frijol de temporal. Se establecieron dos experimentos, uno con 21 variedades nativas y otro con 15 variedades introducidas, de diferente hábito de crecimiento indeterminado, en la Unidad Académica La Ascensión de la Facultad de Agronomía de la Universidad Autónoma de Nuevo León, México en 2009. Los experimentos se condujeron bajo dos tratamientos de humedad del suelo: riego durante todo el ciclo y sequía. En el tratamiento de riego el suelo se mantuvo por encima de 60% de humedad aprovechable durante el ciclo del cultivo, mediante la precipitación y cuatro riegos de auxilio (dos antes y otros dos después de floración, mientras que en el tratamiento de sequía el riego se suspendió a partir del inicio de la floración. En los dos experimentos, bajo la condición de sequía la acumulación de biomasa del vástago y el rendimiento de grano fue significativamente inferior (p? 0.01 que en el tratamiento de riego. En general, el efecto del tratamiento de sequía sobre el peso seco del vástago fue mayor en las variedades nativas, mientras que el efecto sobre el rendimiento de grano fue mayor en las variedades introducidas. En sequía, las variedades de mayor rendimiento, fueron: nativas, Pinto-2, Pinto-1, Amarillo Mantequilla, Boleado, Bayo Blanco, Canelo y Quipincillo Rojo-1 e introducidas, Peruano, Flor de Mayo Media Oreja, Pinto-5 y Ojo de Cabra. De acuerdo con el índice de susceptibilidad a la sequía y la media geométrica, las variedades más eficientes para la producción de rendimiento de grano en ambas condiciones de humedad fueron: Pinto-2, Amarillo Mantequilla, Pinto-1, Boleado, Peruano, Flor de Mayo Media Oreja, Pinto-5 y Ojo de Cabra; sin excepción, todas estas variedades fueron colectadas en la región de prueba, lo que demuestra la importancia de la adaptación local en condiciones de sequía.Intermittent drought is most limiting factor for bean production (Phaseolus vulgaris L. under seasonal conditions in Mexico. Aim of this work was to determine drought effect on biomass accumulation of sprout and grain yield in creole and introduced seasonal bean varieties. Two experiments were set, one with 21 native varieties and another with 15 introduced varieties, from different uncertain type growth habit, at Academic Unit La Asención from Agronomy School of Universidad Autónoma de Nuevo León, Mexico in 2009. Experiments were done under two treatments of soil humidity: irrigation during whole cycle and drought. In irrigation treatment soil was kept above 60% of serviceable humidity during cultivation cycle, by precipitation and four irrigation aids (two before and other two after flowering, while in treatment of drought irrigation was suspended when flowering started. In both experiments, under drought condition biomass accumulation of sprout and grain yield was significantly lower (p? 0.01 than in irrigation treatment. In general, effect of drought treatment on sprout's dry weight was greater in native varieties, while effect on grain yield was greater in introduced varieties. In drought, varieties with higher yield were: native, Pinto-2, Pinto-1, Amarillo Mantequilla, Boleado, Bayo Blanco, Canelo and Quipincillo Rojo-1; and introduced, Peruano, Flor de Mayo Media Oreja, Pinto-5 and Ojo de Cabra. In accordance with drought susceptibility index and geometric average, most efficient varieties for production of grain yield under both humidity conditions were: Pinto-2, Amarillo Mantequilla, Pinto-1, Boleado, Peruano, Flor de Mayo Media Oreja, Pinto-5 and Ojo de Cabra; without exception, all these varieties were collected in test region, which demonstrates importance of local adaptation under drought conditions.

  15. Incremento en biomasa y supervivencia de una plantación de Pinus hartwegii Lindl. en áreas quemadas / Biomass increment and survival of a Pinus hartwegii plantation on burned areas

    Scientific Electronic Library Online (English)

    J. N., Ortíz-Rodríguez; D. A., Rodríguez-Trejo.

    2008-12-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish En el año 2002 se aplicaron quemas prescritas a dos intensidades (alta y baja) y en dos épocas (marzo y mayo) en bosques abiertos de Pinus hartwegii Lindl., en el volcán Ajusco, D. F. También se dejó un testigo, para cada época. En julio del mismo año, se plantaron 450 árboles, correspondientes a do [...] s tamaños (grandes y pequeños). El presente estudio consistió en la evaluación de la supervivencia e incremento de esos árboles tres años después de su plantación. Se registró la supervivencia en toda la plantación y se obtuvo una muestra destructiva de 30 plantas para determinar biomasa. La probabilidad de mortalidad se estimó mediante un modelo logístico. Para el análisis de las demás variables se utilizó el análisis de varianza y la comparación de medias con prueba de diferencia mínima significativa. La probabilidad de mortalidad de los árboles testigo no mostró diferencias con respecto al de las quemas prescritas en el mes de mayo, pero fue menor que la de los tratamientos del mes de marzo, aduciéndose tal respuesta a la competencia más temprana en el mismo, toda vez que las plantaciones no fueron chaponeadas, así como una mayor cobertura y menor presencia de especies nodriza en las áreas quemadas en el mes de marzo. Respecto al incremento, no hubo efecto en los tratamientos. Su valor fue de 8.5 g·año-1 en biomasa total. Abstract in english In the year 2002 prescribed fire treatments were applied on open Pinus hartwegii Lindl., forests in the Ajusco volcano, south of Mexico City, Mexico. The treatments consisted of two fire-intensities: high and low, and two seasons of fire application: March and May, plus an unburned control (one per [...] season). In July of the same year were planted 420 seedlings of two size categories (big and small). In this work were evaluated the survival and biomass increment of such trees three years after plantation establishment. It was recorded the survival in all of the forest plantation and a 30 trees sample was gathered to determine biomass. The mortality probability was estimated with a logistic model. The analysis of variance and the least significant difference test were utilized for the other variables. The probability of mortality of the trees in the control did not show differences with the trees in the May burns, but it was lower than that of the March burns. Such response in the March treatments was adduced to the earlier competition, for the competition in the forest plantation was not eliminated, also to a higher understory cover and to a lesser abundance of nurse shrubs. There was no effect of treatments on tree growth. The total biomass increment was equal to 8.5 g·yr-1.

  16. Biomasa microbiana y actividad ureasa del suelo en una pradera permanente pastoreada de Chile / Soil microbial biomass and urease activity in a grazed permanent pasture from Chile

    Scientific Electronic Library Online (English)

    Pedro Antonio, Núñez Ramos; Alejandra Antonia, Jara Castillo; Yessica, Sandoval Sandoval; Rolando, Demanet; María De La Luz, Mora.

    2012-12-01

    Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish En los sistemas de pasturas; la productividad de la pradera puede estar influenciada por el manejo; debido a su impacto sobre los microorganismos del suelo y el reciclaje de nutrientes. El objetivo de este trabajo fue evaluar la biomasa microbiana (BM) del suelo asociada al nitrógeno (BMN); carbono [...] (BMC) y la actividad ureasa (AU) en una pradera permanente del sur de Chile. Entre la primavera de 2005 y el invierno de 2006 fueron evaluados dos sistemas de pastoreo: pastoreo intenso (PI); pastoreo suave (PS) y un tratamiento control (C). El diseño fue en bloques al azar con tres repeticiones. En relación a los valores promedios medidos de las variables en pre y post pastoreo; se produjo un incremento en los contenidos de CB en un 21,8 y 8,6% para PI y PS; mientras que en el control fue sólo de 1,9%. Los contenidos de NB también fueron incrementados en un 16 y 19% para PI y PS; respectivamente en comparación con el control (4%). La actividad ureasa aumentó en 13 y 27% para PI y PS; respectivamente en comparación con el control (5%). El pastoreo; produce un flujo más alto de residuos orgánicos en el suelo; lo que estimula la actividad de la biomasa microbiana y; por tanto; aumentó la AU y los contenidos de CB y NB. Esto sugiere que; en los sistemas de pastoreo; se mejora la fertilidad biológica de los suelos y la disponibilidad de nutrientes. Abstract in english In pasture systems, management practices can affect pasture productivity differently due to their impact on soil microorganisms and nutrient cycling. The objective of this study was to evaluate the relationship between soil microbial biomass (MB) nitrogen (MBN), carbon (MBC) and urease activity (UA) [...] in a permanent pasture in southern Chile. Two grazing systems were evaluated between spring 2005 and winter 2006 : heavy grazing (HG), light grazing (LG) and a control treatment (C). Treatments were arranged in a randomized block design with three replications. Concerning the average values of the variables measured at the beginning and at the end of grazing, there was an increase in the content of BC of 21.8 and 8.6% for HG and LG, while the control was only 1.9%. BN contents were also increased by 16 and 19% for HG and LG, respectively, compared with the control (4%). The urease activity increased by 13 and 27% for HG and LG, respectively, compared with the control (5%). Grazing produced a higher flow of organic residues in the soil, stimulating microbial biomass and therefore increasing the UA and the BC and BN content. Thus, soil biological fertility and nutrient availability s increase under grazing systems.

  17. Effect of variety and cane yield on sugarcane potential trash Efecto de las variedades y su rendimiento cultural en la biomasa residual potencial

    Directory of Open Access Journals (Sweden)

    Eduardo R. Romero

    Full Text Available Low environmental impact production systems are a major concern in agroindustry and society, with food and sugarcane production being one of the areas where sustainability is a high priority. Green cane harvesting emerges as an important alternative for a cleaner production system, since it excludes the burning of residues, conserves soil and insolves the possibility of energy generation. An estimation of potential sugarcane available trash is very important in order to define management strategies. A research was carried out to determine the amount of dry trash available in cane fields before (SPT and after green cane harvesting (SFT. Also, the relationship between SPT and SFT was studied in order to validate the precision of SPT as an SFT predictor using green cane combine harvesting for the main cultivated varieties in the sugarcane-growing area of Tucumán (LCP 85-384, TUCCP 77-42, CP 65-357 and RA 87-3. An increase in SPT was associated to cane yielding/ha, ranging from 6.9 to 16.0 t/ha of SPT for 32 to 104 t/ha of cane yielding. LCP 85-384 and CP 65-357 produced the highest amount of dry trash before harvest, while TUCCP 77-42 produced the least for similar cane yielding. Simultaneously the DT/CY ratio decreased with a mean value around 16% of cane yield and its use for estimating SPT was limited, as low coefficients of determination highlight. SPT appropriately predicted SFT under green cane combine harvesting conditions and the former one could be estimated using cane yielding/ha.La implementación de sistemas productivos con bajo impacto ambiental es una preocupación tanto para la agroindustria como para la sociedad, resultando la producción de azúcar una de las áreas donde la sustentabilidad es un objetivo prioritario y alcanzable. La cosecha en verde de la caña de azúcar aparece como una importante alternativa para conformar sistemas de producción más limpios, prescindiendo de la quema de material vegetal y residuos de cosecha, conservando el suelo y ofreciendo una posibilidad para la generación de energía. Una estimación del potencial de residuos disponible de la caña de azúcar cobra gran relevancia en el momento de definir estrategias de manejo. Se realizó un estudio para determinar la cantidad de biomasa residual disponible en los cañaverales en forma previa (SPT y posterior (SFT a la cosecha mecanizada en verde para las principales variedades cultivadas en la provincia de Tucumán (LCP 85-384, TUCCP 77-42, CP 65-357 y RA 87-3. Además, se estudió la relación entre SPT y SFT a fin de validar la precisión de SPT como predictor de SFT en el caso de la cosecha integral en verde. El incremento del SPT estuvo asociado al mayor rendimiento cultural/ha, registrándose valores del 6,9 a 16,0 t/ha de biomasa residual para rendimientos culturales de 32 a 104 t/ha. LCP 85-384 y CP 65-357 produjeron el mayor SPT, mientras que TUCCP 77-42 generó la menor cantidad para niveles similares de rendimiento cultural. La relación SPT/CY disminuyó y el promedio general fue del 16% del rendimiento cultural, aunque su uso para estimar SPT fue limitado, como señalan los bajos coeficientes de determinación. SPT predijo adecuadamente SFT para el caso de la cosecha integral en verde, y el primero puede ser estimado adecuadamente empleando el rendimiento cultural/ha.

  18. Relación entre actividad enzimática y biomasa de ensambles fitoplanctónicos en el sistema pelágico / Relationship between enzymatic activity and biomass of phytoplankton assemblages in the pelagic system

    Scientific Electronic Library Online (English)

    José L, Iriarte; Renato A, Quiñones; Rodrigo R, González; Cynthia P, Valenzuela.

    2007-05-01

    Full Text Available SciELO Chile | Language: Spanish Abstract in spanish En ambientes de condiciones fluctuantes y drásticas, las adaptaciones fisiológicas y bioquímicas pueden llegar a ser importantes en la estructuración de ensambles fitoplantónicos. El objetivo de este estudio fue establecer si la actividad enzimática de fitoplancton, como un indicador de su metabolis [...] mo interno dominante, se relaciona con la bio-masa autotrófica. Las áreas geográficas estudiadas correspondieron a: islas Shetlands del Sur (62°S), bahía de Mejillones (22°S) y seno de Reloncaví (41°30’S). En las áreas seleccionadas y mediante una aproximación de terreno, se colectaron muestras para análisis enzimático del metabolismo intermediario del nitrógeno (nitrato reductasa y glutamina sintetasa), biomasa autotrófica y análisis de nutrientes disueltos inorgánicos. En términos de la actividad enzimática fraccionada por tamaño se observó una disminución de la actividad de nitrato reductasa (bS Reloncaví = -0,93; bB Mejillones = -0,65) y glutamina sintetasa (bS Reloncaví = -0,79) con el incremento del tamaño corporal del fitoplancton. Estas pendientes, menores a -1,0, señalan la relativa importancia de ensambles fitoplanctónicos dominados por diatomeas en aguas costeras ricas en nutrientes inorgánicos nitrogenados. Durante el desarrollo de una floración de una especie de dinoflagelado se detectó una elevada actividad de glutamina sintetasa (GS), sugiriendo que ciertas especies de dinoflagelados prefieren las formas de nitrógeno reducido (amonio y urea) en comparación a nitrato o nitrito. La estimación, vía actividad enzimática, de la razón f con valores > 0,5 y Abstract in english In environments with drastically fluctuating conditions, physiological and biochemical adaptations can be important for the structuration of phytoplankton assemblages. The objective of this study was to establish whether the enzymatic activity of the phytoplankton, an indicator of its dominant inter [...] nal metabolism, is related to the autotrophic biomass. The geographic study area covered the South Shetland Islands (62°S), Mejillones Bay (22°S), and Seno de Reloncaví (41°30’S). Samples were collected in the field at the selected sites for enzymatic analyses of the intermediary nitrogen metabolism (nitrate reductase, glutamine synthetase) and autotrophic biomass, as well as dissolved inorganic nutrient analyses. In terms of the size-fractionated enzymatic activity, nitrate reductase (bS Reloncaví = -0.93; bB Mejillones = -0.65) and glutamine synthetase (bS Reloncaví = -0,79) activities decreased as the body size of the phytoplankton increased. These slopes, less than -1.0, indicate the relative importance of diatom-dominated phytoplanktonic assemblages in coastal waters rich in inorganic nitrogenated nutrients. Elevated glutamine synthetase activity (GS) was detected during a bloom of a dinoflagellate species, suggesting that certain dinoflagellate species prefer reduced nitrogen forms (ammonium and urea) over nitrate or nitrite. The estimate, via enzymatic activity, of the f ratio with values > 0.5 and

  19. Biomass and densityofthalassia testudinum beds in mochimabay, Venezuela Biomasa y densidad de praderas de thalassia testudinum en la bahía de mochima, Venezuela

    Directory of Open Access Journals (Sweden)

    Oscar DÍAZ-DÍAZ

    2007-01-01

    Full Text Available Un estudio acerca de las variaciones de la biomasa y densidad de Thalassia testudinum fue realizado en cuatro localidades de la Bahía de Mochima, en la costa nororiental de Venezuela. Entre enero y diciembre de 2002, se tomaron ocho réplicas mensuales de sedimento, empleando un perforador de PVC de 15 cm de diámetro, las mismas fueron tamizadas en una malla de 0,5 mm de apertura. El promedio de la temperatura y salinidad fue o = 27,82 ± 1,26 y = 37,09 ± 0,86 respectivamente. La densidad mensual de Thalassia estuvo comprendida entre 45 ind.m-² (septiembre y 507 ind. m-² (enero ( = 160,64 ± 136,38 ind.m-². El ANOVA mostró diferencias significativas en la variación de la abundancia mensual de la fanerógama (F = 9,643, p A spatial study about the variations of biomass and density of Thalassia testudinum was made in four localities of Mochima Bay, northeastern coast of Venezuela. Between January and December 2002 eight replicate samples were taken monthly, with a core 15 cm in diameter, and the sediment was sieved through a 0.5 mm opening mesh. Temperature and salinity average were or = 27.82 ± 1,26 and = 37.09 ± 0,86 respectively. The monthly density of Thalassia shoots ranged from 45 ind.m-² (September to 507 ind.m-² (January ( = 160.64 ± 136.38 ind.m-². ANOVA showed significant variations of abundance within the months (F = 9.643, p < 0.001 and localities (F = 9.532, p < 0.001. Highest values of density and biomass were obtained in Mangle Quemao and Ensenada de Reyes and the lowest in Toporo. In this last one, the low density and biomass could be attributed to greater abundance of epiphytes on their leaves

  20. INFLUENCIA DEL CLIMA, HUMEDAD DEL SUELO Y ÉPOCA DE FLORACIÓN SOBRE LA BIOMASA Y COMPOSICIÓN NUTRIMENTAL DE FRUTOS DE AGUACATE "HASS" EN MICHOACÁN, MÉXICO

    Directory of Open Access Journals (Sweden)

    Samuel Salazar-Garc\\u00EDa

    2011-01-01

    Full Text Available El amplio periodo de cosecha del aguacate "Hass" en Michoacán se debe a la diversidad de condiciones de cultivo y a la ocurrencia de múltiples flujos vegetativos que resultan en varios flujos de floración y épocas de cosecha. El objetivo de este estudio fue evaluar la influencia de tres condiciones climáticas (semicálido subhúmedo, semicálido húmedo y templado subhúmedo, el régimen de humedad del suelo (con y sin riego y la época de floración ("loca": agosto-septiembre, "normal": diciembre-febrero, y "marceña": febrero-marzo, sobre la biomasa de diferentes partes del fruto y su composición nutrimental. Se seleccionaron seis árboles en cada uno de seis huertos comerciales y de cada árbol se tomaron 10 frutos (¿ 21.5 % materia seca de la pulpa por época de floración. Los frutos fueron seprados en epidermis, pulpa, testa y embrión. A cada parte se le determinó peso fresco (PF, peso seco (PS, materia seca (MS y composición nutrimental. A diferencia del clima y régimen de humedad del suelo, la época de floración afectó el PF, PS y MS de las partes del fruto,así como su composición nutrimental, especialmente K, Ca, Mg, S, Fe, Cu, Mn, Zn y B. En el clima templado subhúmedo se tuvieron los mayores contenidos de N y Mn en epidermis; N, P, K, Ca y Mg en pulpa; Mg, S, Cu y Mn en testa, y B en testa y embrión. Los huertos sin riego mostraron concentraciones más altas de Ca, S y Cu en epidermis; P, K, Mn, Ca y Cu en pulpa; K, Mn y Cu en testa, y de P, K, Mn en embrión

  1. Time at or near VO2max during continuous and intermittent running. A review with special reference to considerations for the optimisation of training protocols to elicit the longest time at or near VO2max.

    Science.gov (United States)

    Midgley, A W; Mc Naughton, L R

    2006-03-01

    Several authors have suggested that training at or near VO2max (i.e. > or = 95% VO2max) is the most effective training intensity to enhance VO2max and that for highly trained endurance athletes, training at or near VO2max may be necessary to increase it further. Consequently, there is an interest in characterising training protocols that allow the longest time at or near VO2max (T@VO2max). Intermittent running protocols have been found to be more effective than continuous protocols for increasing T@VO2max. Intermittent protocols can be manipulated by altering the warm-up intensity and timing, work and relief interval velocity and duration, amplitude, interval number per set, and the number of sets performed. To increase T@VO2max it is recommended that work interval intensity should generally range between 90% and 105% vVO2max and relief interval intensity between 50% vVO2max and the lactate threshold velocity. Work and relief interval durations should be between 15 and 30 seconds. The warm-up period prior to the intermittent protocol should be about 10 to 15 minutes in duration at 1 or 2 km x h(-1) below the lactate threshold velocity, with no gap between the warm-up and the intermittent protocol. When designing intermittent training protocols for the enhancement of VO2max, the simultaneous enhancement of other physiological performance determinants should also be considered. Further experimental research is required to identify the specific physiological responses and adaptations to various intermittent running protocols that are designed to elicit the longest time at or near VO2max, before recommendations can be given to competitive endurance runners. PMID:16596093

  2. Selective synthesis and visible-light photocatalytic activities of BiVO4 with different crystalline phases

    International Nuclear Information System (INIS)

    Tetragonal and monoclinic bismuth vanadate (BiVO4) powders were selectively synthesized by aqueous processes. The characterizations of the as-prepared BiVO4 powders were carried out by X-ray diffraction, nitrogen adsorption, scanning electron microscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic activities of different BiVO4 samples were determined by degradation of methylene blue solution under visible-light irradiation (? > 420 nm) and compared with that of TiO2 (Degussa P25). The band gaps of the as-prepared BiVO4 were determined from UV-vis diffuse reflectance spectra. It was found that monoclinic BiVO4 with a band gap of 2.34 eV showed higher photocatalytic activity than that of tetragonal BiVO4 with a band gap of 3.11 eV

  3. Efecto de aportes superficiales de biomasa vegetal en la temperatura, humedad y dinámica de nemátodos en el suelo en época seca en Santander de Quilichao (Departamento del Cauca. Efecto de aportes superficiales de biomasa vegetal en la temperatura, humedad y dinámica de nemátodos en el suelo en época seca en Santander de Quilichao (Departamento del Cauca

    Directory of Open Access Journals (Sweden)

    Sánchez Marina

    2006-06-01

    Full Text Available

    Effect of superficial contributions of vegetal biomass in the temperature, humidity and dynamics of nematodes in the soil at a season dry time in Santander Quilichao (Department of the Cauca. In the experimental station at CIAT (Santander de Quilichao- Cauca, to 3°06'N and 76°31'W, the effect of surface application of vegetal biomass was explored (6 t dm ha-1 semester-1, after planting of bean. The experiment consisted of four treatments, three cover of the trees that had contrasting characteristics (Calliandra-CAL; Cratylia-CRA and Tithonia - TTH and the control- CON; arranged in a CBRD with 5 repetitions. The evaluated variables were: environmental (humidity and temperature of the soil and biological (abundance and dynamics of the nematodes. Under cover the humidity in a 3% was increased and the soil temperature was regulated from the 0.4 to 0.6°C smaller than the CON treatment. The behavior of the nematodes was very dynamic and was related to the environmental conditions, being favored at wet seasons and by the dynamics of decomposition related to the type of material. In general, the cover modified the microenvironment affecting the population of organisms, generating changes in the aireation, structures and nutrients cycling in the soil by contribution of organic matter through mulch which regule its availability in the productive systems.

    Palabras claves: Suelo, cobertura arbórea, nemátodos, biomasa, factores ambientales.

    En la estación experimental del CIAT (Santander de Quilichao- Cauca, 3°06'N y 76°31'W se exploró el efecto de aplicaciones superficiales de biomasa vegetal (6 t ms ha-1 semestre-1, después de la siembra de fríjol. El ensayo constó de cuatro tratamientos, tres coberturas de árboles de características contrastantes (Calliandra-CAL; Cratylia-CRA y Tithonia -TTH y el testigo CON; dispuestos en un DBCA con 5 repeticiones. Las variables evaluadas fueron ambientales (humedad y temperatura del suelo y biológicas (abundancia y dinámica de los nemátodos. Bajo cobertura se incrementó la hu­medad en 3% y se reguló la temperatura del suelo de 0.4 a 0.6°C menor que CON. El comportamiento de los nemátodos fue muy dinámico y estuvo relacionado con las condiciones ambientales, siendo favorecido en épocas de humedad y por la dinámica de descomposición relacionada con el tipo de material. En general, la cobertura modificó el microambiente afectando la población de organismos, generando cambios en la aireación, estructura y ciclaje de nutrientes en el suelo por aporte de materia orgánica a través de la hojarasca regulando su disponibilidad en los sistemas productivos.

    Palabras claves: Suelo, cobertura arbórea, nemátodos, biomasa, factores ambientales.

  4. Transport phenomena in SrVO3 thin films

    Science.gov (United States)

    Gu, Man; Wolf, Stuart; Lu, Jiwei

    2013-03-01

    Bulk SrVO3 (SVO) with a 3d^1 electronic configuration has been found to exhibit metallic and Pauli paramagnetic behavior. We have obtained epitaxial SVO films grown on various substrates (STO, SLAO, LSAT and LAO) using a pulsed electron-beam deposition (PED) technique. The film transport properties were found to be strongly dependent on the substrate. A 40 nm SVO film deposited on an STO substrate exhibited metallic behavior with the electrical resistivity following a T^2 law that corresponds to a Fermi liquid system, the resistance ratio R(300K)/R(2K) was ˜ 1.66. Hall measurements showed that the mobility increased slightly as the temperature was decreased. A small positive out-of-plane magnetoresistance was observed, it was only 0.045% at 5 K and 7 Tesla. SVO films with the same thickness grown on SLAO, LSAT and LAO showed semiconducting behavior, the different transport properties in the SVO films could be attributed to the compressive film strain or the different film-substrate interfaces.

  5. VO-KOREL: A Fourier disentangling service of Virtual Observatory

    CERN Document Server

    Škoda, Petr; Fuchs, Jan

    2011-01-01

    VO-KOREL is a web service exploiting the technology of Virtual Observatory for providing the astronomers with the intuitive graphical front-end and distributed computing back-end running the most recent version of Fourier disentangling code KOREL. The system integrates the ideas of the e-shop basket, conserving the privacy of every user by transfer encryption and access authentication, with features of laboratory notebook, allowing the easy housekeeping of both input parameters and final results, as well as it explores a newly emerging technology of cloud computing. While the web-based front-end allows the user to submit data and parameter files, edit parameters, manage a job list, resubmit or cancel running jobs and mainly watching the text and graphical results of a disentangling process, the main part of the back-end is a simple job queue submission system executing in parallel multiple instances of FORTRAN code KOREL. This may be easily extended for GRID-based deployment on massively parallel computing cl...

  6. Zooplankton richness, abundance and biomass of two hypertrophic shallow lakes with different salinity in central Argentina / Riqueza, abundancia y biomasa zooplanctónica de dos lagos someros hipertróficos de distinta salinidad de la región central de Argentina

    Scientific Electronic Library Online (English)

    Santiago Andrés, Echaniz; Alicia María, Vignatti; Gabriela Cecilia, Cabrera; Susana Beatriz José de, Paggi.

    2012-06-01

    Full Text Available El zooplancton lacustre es controlado por parámetros biológicos y fisicoquímicos. Entre los primeros, la depredación por peces puede determinar el reemplazo de especies de talla grande por pequeñas y entre los segundos la salinidad ejerce efectos negativos sobre la riqueza y abundancia. Dado que se [...] ha indicado que los lagos salinos sin peces tienen mayores biomasas zooplanctónicas que los de baja salinidad, el objetivo de este trabajo es conocer la riqueza, abundancia y biomasa del zooplancton de dos lagos de diferente salinidad y probar la hipótesis de que a iguales concentraciones de nutrientes y clorofila "a" los lagos salinos tienen mayor biomasa que los de baja salinidad. El estudio se desarrolló en dos lagos de la provincia de La Pampa, en el centro de Argentina, uno subsalino y otro hiposalino, que compartieron elevadas concentraciones de clorofila a y fósforo total, reducida transparencia y presencia de un pez planctófago. Aunque la riqueza resultó diferente y más elevada en el lago subsalino, no ocurrió lo mismo con la abundancia y biomasa totales, ni al considerar los grupos taxonómicos por separado. La presencia de un pez planctívoro halotolerante controló la talla del zooplancton debido a la depredación sobre las especies de mayor tamaño e impidió el desarrollo de mayor biomasa en el lago salino, lo que constituye una importante diferencia con situaciones registradas anteriormente. Este estudio mostró que a pesar de la diferencia en la salinidad, el efecto en cascada en la cadena trófica (top down) es un factor que iguala la biomasa zooplanctónica al permitir sólo el desarrollo de especies pequeñas y pone en evidencia la importancia de la depredación por peces en la determinación de las concentraciones de clorofila y transparencia del agua. Abstract in english The zooplankton of lakes is controlled by biological and physico-chemical parameters. Among the former, predation by fish can determine the replacement of large-sized species by small-sized ones and among the latter, salinity exerts negative effects on richness and abundance. Since it has been sugge [...] sted that saline lakes without fishes have higher zooplankton biomass than low salinity ones, the aim of this study was to determine the richness, abundance and biomass of zooplankton in two lakes with different salinity and test the hypothesis that in the presence of zooplanktivorous fishes and at equal concentrations of nutrients and chlorophyll-a, saline lakes have higher biomass than those with low salinity. The study was conducted in two shallow lakes of the Province of La Pampa (central Argentina): a subsaline lake and a hyposaline lake, which shared high concentrations of chlorophyll-a and total phosphorus, reduced transparency and presence of planktivorous fish. Zooplankton richness was different and higher in the subsaline lake, whereas abundance and total biomass were similar, even when the taxonomic groups were considered separately. It is suggested that the presence of a halotolerant planktivorous fish controlled the size of zooplankton due to the predation on larger species and prevented the development of higher biomass in the saline lake, which is an important difference from previously recorded situations. This study shows that, regardless of the differences in salinity, the top-down effect in the food chain may have been a factor that equalized the zooplankton biomass by allowing only the development of small species and highlights the possible importance of fish predation in determining chlorophyll-a concentrations and water transparency.

  7. EVALUACIÓN DEL CONTENIDO DE NUTRIENTES Y PRODUCCIÓN DE BIOMASA EN CEPAS DE LEVADURA COLOMBIANAS Y COMERCIALES EVALUATION OF THE NUTRIENT CONTENT AND BIOMASS PRODUCTION IN COLOMBIAN AND COMMERCIAL YEAST STRAINS

    Directory of Open Access Journals (Sweden)

    Nohora Patricia Manovacía Moreno

    2008-12-01

    Full Text Available En el presente estudio se evaluó la producción de biomasa, el contenido de algunos nutrientes (selenio, carbohidratos totales y proteína microbiana y el consumo de sustrato de cepas de levaduras comerciales y nativas pertenecientes al Banco de Germoplasma de la Nación Colombiana, manejado por la Corporación Colombiana de Investigación Agropecuaria, CORPOICA. Inicialmente se determinó el crecimiento de tres levaduras nativas seleccionadas al azar bajo diferentes condiciones de pH, temperatura y tiempo de fermentación usando un medio líquido de extracto de malta. Dentro de estas condiciones, las mejores respuestas se observaron a pH de 4,5, 25 °C y 24 horas de fermentación. Usando estas condiciones se evaluaron 100 accesiones de levaduras nativas y 4 comerciales por su producción de biomasa, contenido de selenio, carbohidratos totales y proteína microbiana y consumo de sustratos. De acuerdo con estas variables y un análisis de conglomerados fue posible agrupar las levaduras en grupos homogéneos. Hubo elevada variabilidad en la producción de biomasa entre las 104 cepas evaluadas, probablemente debido a la variabilidad biológica existente en la población estudiada. Los rendimientos de biomasa variaron entre 0,101 y 0,480 g de biomasa g-1 de azúcar consumido y las velocidades de producción de biomasa oscilaron entre 0,040 y 0,185 g L-1 h-1. El consumo promedio de nutrientes (g de nutrientes consumidos/ g de nutrientes disponibles fue de 91,6% en el caso de los carbohidratos y de 17,8% en el caso de la proteína. Se identificaron diez cepas de superior crecimiento y contenido de nutrientes, cuyo potencial prebiótico y probiótico será evaluado en futuros ensayos In vivo.In the present study biomass production and nutrient (selenium, total carbohydrate and microbial protein were evaluated in both commercial and native yeast isolates from the Colombian Germplasm Bank managed by the Colombian Corporation of Agricultural Research, CORPOICA. In an initial phase, three randomly chosen yeast isolates were grown under different conditions of pH, temperature and time of fermentation using liquid malt extract culture medium. The best responses in biomass yield were observed at a pH of 4.5, or temperature of 25 °C and a fermentation period of 24 hours. Using these conditions, 100 native and 4 commercial yeast isolates, were evaluated for their biomass production, content of selenium, total carbohydrates and microbial protein and nutrient intake. According to these variables, a cluster analysis was used to distribute the 104 isolates in homogeneous groups. Great variability in biomass production was observed among isolates, probably due to the existing biological variability in the population studied. Biomass yields varied from 0.101 to 0.480 g of biomass/ g of sugar consumed and rate of biomass production ranged between 0.040 to 0.185 g L-1 h-1. Average nutrient intake (g of consumed nutrients/ g of available nutrients was of 91.6% in the case of carbohydrates and of 17.8% in the case of protein. Ten yeast isolates with superior growth and nutrient content were identified for future screening for prebiotic and probiotic potential.

  8. EVALUACIÓN DEL CONTENIDO DE NUTRIENTES Y PRODUCCIÓN DE BIOMASA EN CEPAS DE LEVADURA COLOMBIANAS Y COMERCIALES / EVALUATION OF THE NUTRIENT CONTENT AND BIOMASS PRODUCTION IN COLOMBIAN AND COMMERCIAL YEAST STRAINS

    Scientific Electronic Library Online (English)

    Nohora Patricia, Manovacía Moreno; Angélica María, Moreno Cárdenas; Olga Lucía, Mayorga Mogollón; Rolando, Barahona Rosales.

    2008-12-01

    Full Text Available En el presente estudio se evaluó la producción de biomasa, el contenido de algunos nutrientes (selenio, carbohidratos totales y proteína microbiana) y el consumo de sustrato de cepas de levaduras comerciales y nativas pertenecientes al Banco de Germoplasma de la Nación Colombiana, manejado por la Co [...] rporación Colombiana de Investigación Agropecuaria, CORPOICA. Inicialmente se determinó el crecimiento de tres levaduras nativas seleccionadas al azar bajo diferentes condiciones de pH, temperatura y tiempo de fermentación usando un medio líquido de extracto de malta. Dentro de estas condiciones, las mejores respuestas se observaron a pH de 4,5, 25 °C y 24 horas de fermentación. Usando estas condiciones se evaluaron 100 accesiones de levaduras nativas y 4 comerciales por su producción de biomasa, contenido de selenio, carbohidratos totales y proteína microbiana y consumo de sustratos. De acuerdo con estas variables y un análisis de conglomerados fue posible agrupar las levaduras en grupos homogéneos. Hubo elevada variabilidad en la producción de biomasa entre las 104 cepas evaluadas, probablemente debido a la variabilidad biológica existente en la población estudiada. Los rendimientos de biomasa variaron entre 0,101 y 0,480 g de biomasa g-1 de azúcar consumido y las velocidades de producción de biomasa oscilaron entre 0,040 y 0,185 g L-1 h-1. El consumo promedio de nutrientes (g de nutrientes consumidos/ g de nutrientes disponibles) fue de 91,6% en el caso de los carbohidratos y de 17,8% en el caso de la proteína. Se identificaron diez cepas de superior crecimiento y contenido de nutrientes, cuyo potencial prebiótico y probiótico será evaluado en futuros ensayos In vivo. Abstract in english In the present study biomass production and nutrient (selenium, total carbohydrate and microbial protein) were evaluated in both commercial and native yeast isolates from the Colombian Germplasm Bank managed by the Colombian Corporation of Agricultural Research, CORPOICA. In an initial phase, three [...] randomly chosen yeast isolates were grown under different conditions of pH, temperature and time of fermentation using liquid malt extract culture medium. The best responses in biomass yield were observed at a pH of 4.5, or temperature of 25 °C and a fermentation period of 24 hours. Using these conditions, 100 native and 4 commercial yeast isolates, were evaluated for their biomass production, content of selenium, total carbohydrates and microbial protein and nutrient intake. According to these variables, a cluster analysis was used to distribute the 104 isolates in homogeneous groups. Great variability in biomass production was observed among isolates, probably due to the existing biological variability in the population studied. Biomass yields varied from 0.101 to 0.480 g of biomass/ g of sugar consumed and rate of biomass production ranged between 0.040 to 0.185 g L-1 h-1. Average nutrient intake (g of consumed nutrients/ g of available nutrients) was of 91.6% in the case of carbohydrates and of 17.8% in the case of protein. Ten yeast isolates with superior growth and nutrient content were identified for future screening for prebiotic and probiotic potential.

  9. Upconversion spectrum of Tm,Ho:GdVO4 pumped by pulse and CW laser at 800 nm

    International Nuclear Information System (INIS)

    The different upconversion dynamic processes in Tm,Ho:GdVO4 crystal pumped by 100 fs pulse laser and continue-wave diode laser at 800 nm are analyzed. A phonon-helped absorption theory is used to explain the different upconversion processes in Tm,Ho:YLF and Tm,Ho:GdVO4. In addition, the lifetime 16 ?s of Ho:5S2 level in GdVO4 is firstly measured

  10. Transport of the anti-diabetic VO2+ complexes formed by pyrone derivatives in the blood serum.

    Science.gov (United States)

    Sanna, Daniele; Bíró, Linda; Buglyó, Péter; Micera, Giovanni; Garribba, Eugenio

    2012-10-01

    The biotransformation in the blood serum of the two anti-diabetic agents [VO(ema)(2)] - or BEOV - and [VO(koj)(2)] formed by ethylmaltol (Hema) and kojic acid (Hkoj) was studied with EPR spectroscopy, pH-potentiometry and DFT calculations. For comparison, the behavior of the systems with tropolone (Htrop) was also analyzed. The interaction of [VO(ema)(2)] and [VO(koj)(2)] with the most important bioligands of the serum, lactic (Hlact) and citric acid (H(3)citr), human serum transferrin (hTf), human serum albumin (HSA) and immunoglobulin G (IgG) was examined and discussed. Among the several mixed species observed, cis-VO(carrier)(2)(hTf), cis-VO(carrier)(2)(HSA) and cis-VO(carrier)(2)(IgG), where carrier is ethylmaltolate or kojate, with a His-N of the protein coordinated in the equatorial position, are plausible candidates for the transport processes of the drug toward the target organs. The values of the log? are in the range 19.6-19.8 for the species formed by ethylmaltol and 17.4-17.6 for those formed by kojic acid. The formation of such species was confirmed through pH-titrations of the model systems VO(2+)/carrier/1-MeIm and VO(2+)/carrier/Ac-his, where 1-MeIm and Ac-his are 1-methylimidazole and N-acetylhistamine, and DFT calculations of (51)V A(z) of the model species cis-[VO(carrier)(2)(1-MeIm)] and cis-[VO(carrier)(2)(Ac-his)]. The values of the stability constants for the mixed species observed were used to predict the biodistribution of VO(2+) ion between the blood serum components for concentrations of 1, 10 and 50 ?M. PMID:22926028

  11. Short range ferromagnetic order in Mn-doped quasi one-dimensional LiCuVO4

    International Nuclear Information System (INIS)

    The magnetic properties of Mn-doped LiCuVO4 were investigated. For the first time it has been observed that with Mn-doping the long range ferromagnetic ordering is induced in one dimensional antiferromagnetic LiCuVO4. With doping the angle between Cu-O-Cu chain decreases (from ? 95° towards 90°) and also the intrachain exchange interaction decreases and hence Mn-doping induces short range ferromagnetic ordering in LiCuVO4

  12. In situ high-pressure synchrotron x-ray diffraction study of CeVO[subscript 4] and TbVO[subscript 4] up to 50 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Errandonea, D.; Kumar, R.S.; Achary, S.N.; Tyagi, A.K. (UNLV); (Valencia); (BARC)

    2012-02-07

    Room-temperature angle-dispersive x-ray diffraction measurements on zircon-type TbVO{sub 4} and CeVO{sub 4} were performed in a diamond-anvil cell up to 50 GPa using neon as a pressure-transmitting medium. In TbVO{sub 4}, we found at 6.4 GPa evidence of a nonreversible pressure-induced structural phase transition from zircon to a scheelite-type structure. A second transition to an M-fergusonite-type structure was found at 33.9 GPa, which is reversible. Zircon-type CeVO{sub 4} exhibits two pressure-induced transitions: first, an irreversible transition to a monazite-type structure at 5.6 GPa and, second, at 14.7 GPa, a reversible transition to an orthorhombic structure. No additional phase transitions or evidences of chemical decomposition are found in the experiments. The equations of state and axial compressibility for the different phases are also determined. Finally, the sequence of structural transitions and the compressibilities are discussed in comparison with other orhtovanadates and the influence of nonhydrostaticity commented.

  13. In situ high-pressure synchrotron x-ray diffraction study of CeVO4 and TbVO4 up to 50 GPa

    Science.gov (United States)

    Errandonea, D.; Kumar, R. S.; Achary, S. N.; Tyagi, A. K.

    2011-12-01

    Room-temperature angle-dispersive x-ray diffraction measurements on zircon-type TbVO4 and CeVO4 were performed in a diamond-anvil cell up to 50 GPa using neon as a pressure-transmitting medium. In TbVO4, we found at 6.4 GPa evidence of a nonreversible pressure-induced structural phase transition from zircon to a scheelite-type structure. A second transition to an M-fergusonite-type structure was found at 33.9 GPa, which is reversible. Zircon-type CeVO4 exhibits two pressure-induced transitions: first, an irreversible transition to a monazite-type structure at 5.6 GPa and, second, at 14.7 GPa, a reversible transition to an orthorhombic structure. No additional phase transitions or evidences of chemical decomposition are found in the experiments. The equations of state and axial compressibility for the different phases are also determined. Finally, the sequence of structural transitions and the compressibilities are discussed in comparison with other orhtovanadates and the influence of nonhydrostaticity commented.

  14. In situ high-pressure synchrotron x-ray diffraction study of CeVO4 and TbVO4 up to 50 GPa

    CERN Document Server

    Errandonea, D; Achary, S N; Tyagi, A K; 10.1103/PhysRevB.84.024111

    2012-01-01

    Room temperature angle-dispersive x-ray diffraction measurements on zircon-type TbVO4 and CeVO4 were performed in a diamond-anvil cell up to 50 GPa using neon as pressure-transmitting medium. In TbVO4 we found at 6.4 GPa evidence of a non-reversible pressure-induced structural phase transition from zircon to a scheelite-type structure. A second transition to an M-fergusonite-type structure was found at 33.9 GPa, which is reversible. Zircon-type CeVO4 exhibits two pressure-induced transitions. First an irreversible transition to a monazite-type structure at 5.6 GPa and second at 14.7 GPa a reversible transition to an orthorhombic structure. No additional phase transitions or evidences of chemical decomposition are found in the experiments. The equations of state and axial compressibility for the different phases are also determined. Finally, the sequence of structural transitions and the compressibilities are discussed in comparison with other orhtovanadates and the influence of non-hydrostaticity commented.

  15. Ecuaciones alométricas para estimar biomasa aérea de Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. Johnst. / Allometric equations to estimate aerial biomass of Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C. Johnst.

    Scientific Electronic Library Online (English)

    Jorge, Méndez González; Osvaldo Augusto, Turlan Medina; Julio Cesar, Ríos Saucedo; Juan Abel, Nájera Luna.

    2012-10-01

    Full Text Available La medición y evaluación de la biomasa aérea de árboles juega un papel importante en el manejo de los recursos forestales. Existen muchos modelos alométricos para especies tropicales y subtropicales, pero muy pocos para las zonas semiáridas. Un total de 144 árboles de Prosopis laevigata, de siete ro [...] dales naturales localizados en el noreste de México, fueron muestreados por un método destructivo con la finalidad de desarrollar ecuaciones para la predicción de la biomasa total. La selección de los individuos cubrió varios intervalos de diámetro basal (5.2 a 41.8 cm) y de altura (1.4 a 9.7 m). Se contrastaron procedimientos de ajuste no-lineal y lineal de la ecuación alométrica y = a·x b + ?, para estimar la biomasa aérea de P. laevigata. Aunque, el procedimiento no-lineal tuvo el mejor ajuste (R² = 0.95 y P Abstract in english The measurement and assessment of aboveground tree biomass plays a key role in the management of forest resources. Many allometric models exist for tropical and subtropical species, but only a few studies for species of semiarid zones. A total of 144 Prosopis laevigata trees from seven native stands [...] (sites) located in northeast Mexico, were destructively sampled to develop total biomass prediction equations. Sampling covered various ranges of basal diameter (5.2 to 41.8 cm) and height (1.4 to 9.7 m). Here, we contrast nonlinear and linear fitting approaches of the allometric equation y = a·x b + ?, for estimating aboveground biomass of Prosopis laevigata. Although nonlinear procedure had the best fits (R² = 0.95 and P

  16. DISTRIBUTION AND BIOMASS OF RUPPIA FILIFOLIA (PHIL.) SKOTTSBERG, (RUPPIACEAE) IN SKYRING SOUND, SUB-ANTARCTIC ECOREGION OF MAGALLANES, CHILE / DISTRIBUCIÓN Y BIOMASA DE RUPPIA FILIFOLIA (PHIL.) SKOTTSBERG, (RUPPIACEAE) EN EL SENO SKYRING, ECOREGIÓN SUBANTÁRTICA DE MAGALLANES, CHILE

    Scientific Electronic Library Online (English)

    Andrés, Mansilla; Pedro, Ramírez-García; Silvia, Murcia; Jorge, Terrados.

    Full Text Available SciELO Chile | Language: English Abstract in spanish Ruppia filifolia es el pasto marino con la distribución más austral del planeta y del que se desconoce incluso los aspectos más básicos de su biología y ecología. Se evalúa la presencia, distribución batimétrica y biomasa alcanzada por las praderas R. filifolia en seno Skyring (ecoregión subantártic [...] a de Magallanes, Chile) mediante prospección remota con una cámara de video, y verificación directa y muestreo por buceadores. El litoral del seno Skyring está rodeado por praderas fragmentadas de R. filifolia hasta una profundidad de 5,3 m en bandas de 100-160 m de anchura. R. filifolia alcanza una biomasa de 80 g peso seco m-2 con una asignación relativa de biomasa a rizomas más raíces frente a hojas de 1,6 a 1,9 y una densidad de 2.000 haces foliares m-2. Se discute la importancia de este pasto marino en el funcionamiento del ecosistema costero somero del seno Skyring. Abstract in english Ruppia filifolia is the seagrass with the world's southernmost distribution and a species about which even the most fundamental aspects of its biology and ecology are not known. Presence, bathymetric distribution, and biomass of R. filifolia meadows in Skyring sound (sub-antarctic ecoregion of Magal [...] lanes, Chile) were evaluated through a remotely operated vehicle (ROV) survey, and direct verification and sampling by divers. The littoral of Skyring sound is surrounded by patchy R. filifolia meadows to a depth of 5.3 m in bands 100-160 m wide. R. fillfolla achieved a biomass of 80 g dry weight m-2, a rhizomes plus roots to leaves biomass ratio of 1.6 to 1.9 and a density of 2.000 shoots m-2. Possible relevance of meadows formed by this seagrass species in the functioning of the shallow coastal ecosystem of Skyring sound is discussed.

  17. Facile fabrication of an efficient BiVO4 thin film electrode for water splitting under visible light irradiation.

    Science.gov (United States)

    Jia, Qingxin; Iwashina, Katsuya; Kudo, Akihiko

    2012-07-17

    An efficient BiVO(4) thin film electrode for overall water splitting was prepared by dipping an F-doped SnO(2) (FTO) substrate electrode in an aqueous nitric acid solution of Bi(NO(3))(3) and NH(4)VO(3), and subsequently calcining it. X-ray diffraction of the BiVO(4) thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO(4) was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO(4) film with 300-400 nm of the thickness. The BiVO(4) thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag/AgCl. Modification with CoO on the BiVO(4) electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO(4) thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H(2) and O(2) was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO(3)Rh photocathode and the BiVO(4) photoanode. PMID:22699499

  18. Temperature-agile and structure-tunable optical properties of VO{sub 2}/Ag thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.R.; Hu, X. [University of Science and Technology of China, Advanced Applied Research Center, Hefei National Laboratory for Physical Sciences at the Microscale, Anhui (China); Wang, W. [University of Science and Technology of China, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Hefei (China); The University of Texas at Austin, Department of Materials Science and Engineering, Austin, TX (United States); Zhao, Y. [University of Science and Technology of China, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Hefei (China); Reinhardt, K. [United States Air Force Office of Scientific Research, Arlington, VA (United States); Knize, R.J. [United States Air Force Academy, Laser Optics Research Center, Physics Department, Colorado Springs, CO (United States); Lu, Yalin [University of Science and Technology of China, Advanced Applied Research Center, Hefei National Laboratory for Physical Sciences at the Microscale, Anhui (China); University of Science and Technology of China, CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, Hefei (China); United States Air Force Academy, Laser Optics Research Center, Physics Department, Colorado Springs, CO (United States)

    2012-12-15

    By integrating together VO{sub 2}'s unique near-room-temperature (RT) semiconductor-metal (S-M) phase transition with a thin silver (Ag) layer's plasmonic properties, VO{sub 2}/Ag multilayers could present a much enhanced optical transmission change when increasing the temperature from RT to over VO{sub 2}'s S-M phase-transition temperature. Changing VO{sub 2} and Ag layer thicknesses can also significantly tune their transmission and absorption properties, which could lead to a few useful designs in optoelectronic and energy-saving industries. (orig.)

  19. Resistance switching of epitaxial VO2/Al2O3 heterostructure at room temperature induced by organic liquids

    Science.gov (United States)

    Yang, Mengmeng; Yang, Yuanjun; Hong, Bin; Huang, Haoliang; Hu, Sixia; Dong, Yongqi; Wang, Haibo; He, Hao; Zhao, Jiyin; Liu, Xuguang; Luo, Zhenlin; Li, Xiaoguang; Zhang, Haibin; Gao, Chen

    2015-03-01

    We studied using organic liquids (cyclohexane, n-butanol, and ethylene glycol) to modulate the transport properties at room temperature of an epitaxial VO2 film on a VO2/Al2O3 heterostructure. The resistance of the VO2 film increased when coated with cyclohexane or n-butanol, with maximum changes of 31% and 3.8%, respectively. In contrast, it decreased when coated with ethylene glycol, with a maximum change of -7.7%. In all cases, the resistance recovered to its original value after removing the organic liquid. This organic-liquid-induced reversible resistance switching suggests that VO2 films can be used as organic molecular sensors.

  20. Preparation and characterizations of BiVO?/reduced graphene oxide nanocomposites with higher visible light reduction activities.

    Science.gov (United States)

    Wang, Aolan; Shen, Song; Zhao, Yibo; Wu, Wei

    2015-05-01

    Bismuth vanadate/reduced graphene oxide (BiVO4/RGO) composites were synthesized by one-step hydrothermal method with graphite oxide, Bi(NO3)3 and NH4VO3 as precursors. The as-synthesized nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Vis spectroscopy (UV), fluorescence spectroscopy (FL) and electrochemical impedance spectroscopy (EIS). The reduced graphene oxide sheets were decorated by butterfly-like BiVO4 lamellas. Such combination not only alleviated the agglomeration of BiVO4 particles but also restrained the restacking of reduced graphene oxide. A preliminary study on the photo-reductions of Cr (VI) and CO2 under the illumination of simulated sunlight with as-synthesized BiVO4/RGO nanocomposites as catalyst was carried out. The nanocomposites showed better photo-catalytic activity than the conventional BiVO4 particles. The photo-reduction efficiency of BiVO4/RGO nanocomposites increased about 50.1% and the ethanol yield improved about 15.4 ?mol/g-cat comparing with pure BiVO4. The enhancements of the photo-catalytic activities were attributed to the effective charge transfer of photo-generated electron from BiVO4 to RGO and improved absorption performance. PMID:25643960

  1. Interaction of VO2+ ion with human serum transferrin and albumin.

    Science.gov (United States)

    Sanna, Daniele; Garribba, Eugenio; Micera, Giovanni

    2009-04-01

    The complexation of VO(2+) ion with the high molecular mass components of the blood serum, human serum transferrin (hTf) and albumin (HSA), has been re-examined using EPR spectroscopy. In the case of transferrin, the results confirm those previously obtained, showing that VO(2+) ion occupies three different binding sites, A, B(1) and B(2), distinguishable in the X-band anisotropic spectrum recorded in D(2)O. With albumin the results show that a dinuclear complex (VO)(2)(d)HSA is formed in equimolar aqueous solutions or with an excess of protein; in the presence of an excess of VO(2+), the multinuclear complex (VO)(x)(m)HSA is the prevalent species, where x=5-6 indicates the equivalents of metal ion coordinated by HSA. The structure of the dinuclear species is discussed and the donor atoms involved in the metal coordination are proposed on the basis of the measured EPR parameters. Two different binding modes of albumin can be distinguished varying the pH, with only one species being present at the physiological value. The results show that the previously named "strong" site is not the N-terminal copper binding site, and some hypothesis on the metal coordination is discussed, with the (51)V A(z) values for the proposed donor sets obtained by DFT (density functional theory) calculations. Finally, preliminary results obtained in the ternary system VO(2+)/hTf/HSA are shown in order to determine the different binding strength of the two proteins. Due to the low VO(2+) concentration used, the recording of the EPR spectra through the repeated acquisition of the weak signals is essential to obtain a good signal to noise ratio in these systems. PMID:19201482

  2. Thermochromic undoped and Mg-doped VO2 thin films and nanoparticles: Optical properties and performance limits for energy efficient windows

    International Nuclear Information System (INIS)

    Undoped and Mg-doped thermochromic VO2 films with atom ratios z???Mg/(Mg?+?V) of 0???z?lum and solar transmittance modulation ?Tsol compared to undoped VO2 films, and both of these parameters could be further enhanced by anti-reflection. VO2-containing nanocomposites had much larger values of Tlum and ?Tsol than VO2-based films. Mg-doping was found to erode the properties of the nanocomposites. Approximate performance limits are given on Tlum and ?Tsol for thermochromic VO2 films, with and without Mg doping and antireflection coating, and also for VO2-containing dilute nanocomposites

  3. NUEVAS PERSPECTIVAS PARA EL ESTUDIO DE LA ASIGNACIÓN DE BIOMASA Y SU RELACIÓN CON EL FUNCIONAMIENTO DE PLANTAS EN ECOSISTEMAS NEOTROPICALES New Perspectives to Study the Biomass Allocation and its Relationship with the Functioning of Plants in Neotropical Ecosystems

    Directory of Open Access Journals (Sweden)

    IVÁN DARÍO CAMARGO RODRÍGUEZ

    Full Text Available Cómo responden las plantas a la variabilidad en la disponibilidad de los recursos abióticos, es un tema central en estudios de fisiología ecológica. Varios modelos de partición óptima han sugerido un balance funcional en la biomasa asignada al vástago y la raíz con la siguiente predicción: "las plantas cambiarían su asignación de biomasa hacia el vástago si la ganancia de carbono de la parte aérea de la planta es afectada por un nivel bajo de recursos sobre el suelo, tal como luz o CO2. Igualmente, las plantas cambiarían su asignación hacia la raíz si el nivel de los recursos del suelo es bajo, tal como nutrientes y agua". Estos cambios en la asignación pueden ser considerados como adaptativos, ya que permiten a la planta capturar más de aquel recurso que limita fuertemente su crecimiento. En este trabajo, discutimos algunos esquemas metodológicos que a través de la descripción y análisis de la asignación de biomasa pretenden probar dicha predicción. Enfatizamos que la conclusión extraída en contra o a favor de la predicción se fundamenta en la interpretación del término plasticidad, conllevando recientemente al uso de metodologías que sugieren que la predicción no se cumple en respuesta a la disponibilidad de algunos recursos. Proponemos la utilización de un protocolo de investigación para estudiar los patrones de asignación de biomasa y sugerimos una metodología para cuantificar la plasticidad de diferentes genotipos desde un punto de vista discreto.How plants respond to variation in the availability of abiotic resources is a central research topic in physiological ecology. Several optimal partitioning models have suggested a functional balance in the biomass allocated to the shoot and root with the following prediction: "plants shift their allocation towards shoots if the carbon gain of the shoot is impaired by a low level of aboveground resources, such as light and CO2. Similarly, plants shift allocation towards roots at a low level of belowground resources, such as nutrients and water". These shifts could be seen as adaptive, as they enable the plant to capture more of those resources that most strongly limit plant growth. Some methodological frameworks pretend to prove this prediction trough the description and analysis of biomass allocation, these are discussing here. We emphasize that the conclusion in favor or against of this prediction is due to interpret in different ways the plasticity term. The last have induced to use methodologies which are suggesting that the prediction not be fulfilled in response to the availability of some resources. We propose the utilization of a research protocol to study biomass allocation patterns and suggest a methodology to quantify the plasticity of different genotypes from a discrete viewpoint.

  4. INFLUENCE OF DIFFERENT DIETS ON LENGTH AND BIOMASS PRODUCTION OF BRINE SHRIMP ARTEMIA FRANCISCANA (KELLOG, 1906)A. / INFLUENCIA DE DIFERENTES DIETAS EN LA LONGITUD Y LA PRODUCCIÓN EN BIOMASA DE LA ARTEMIA FRANCISCANA.

    Scientific Electronic Library Online (English)

    Manuel, García-Ulloa Gómez; Julián, Gamboa Delgado; José Luis, Zavala Aguirre; Tetsuya, Ogura Fujii; Patrick, Lavens.

    1999-12-01

    Full Text Available Se evaluó la longitud total y la producción de biomasa de Artemia franciscana aplicando harinas micropulverizadas de soya y trigo (como ración única o mezcladas), microalgas vivas (Tetraselmis suecica y Chaetoceros calcitrans) y Spirulina seca como dietas experimentales. 8 dietas fueron examinadas p [...] or triplicado durante 10 días. Se observaron diferencias significativas (P Abstract in english Total length and biomass production of the brine shrimp Artemia franciscana were studied fed on soybean and wheat micropulverized meals (applied alone or mixed at different proportions), live microalgae (Tetraselmis suecica and Chaetoceros calcitrans), and dried Spirulina as diets. Eight diets were [...] tested in triplicates during 10 days. Significant differences (P

  5. Ecuaciones alométricas para estimar biomasa y carbono de cuatro especies leñosas neotropicales con potencial para la restauración / Allometric equations used to estimate biomass and carbon in four neotropical tree species with restoration potential

    Scientific Electronic Library Online (English)

    David, Douterlungne; Angel M., Herrera-Gorocica; Bruce G., Ferguson; Ilyas, Siddique; Lorena, Soto-Pinto.

    2013-06-30

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Un reto ambiental actual es reducir los gases de efecto invernadero (GEI) a través de la reforestación. Las plantaciones forestales con las especies y manejo adecuados secuestran carbono y recuperan áreas degradadas simultáneamente, pero es necesario refinar los métodos para estimar su biomasa. En l [...] a Selva Lacandona en México se cosecharon 103 árboles para determinar ecuaciones alométricas para cuatro especies abundantes en los Neotrópicos y con alto potencial pata la restauración: Guazuma ulmifolia, Trichospermum mexicanum, Inga vera y Ochroma pyramidale. Los mejores predictores de la biomasa fueron el diámetro a la altura del pecho y en la base; con ellos se generaron relaciones alométricas con r² mayor a 0.90. Con base en estas relaciones la acumulación promedio de biomasa en plantaciones mono-específicas de dos años de Inga, Ochroma, Trichospermum y Guazuma se calculó en 6.60, 30.80, 47.62 y 48.12 Mg ha-1. Plantaciones de restauración con las dos últimas especies son una estrategia potencialmente eficiente para reducir el carbono atmosférico. La variabilidad alta inter-sitio e inter-especie, en parte relacionada con las diferencias en supervivencia y crecimiento, indica que diseños experimentales multisitios son necesarios para generalizar los resultados de estimación de biomasa. Abstract in english One of today's environmental challenges is reducing greenhouse gases (GHG) through reforestation. Forest plantations with adequate species composition and management sequester carbon and restore degraded areas simultaneously, but methods to estimate their biomass must be refined. In Mexico's Lacando [...] n Jungle, 103 trees were harvested to determine allometric equations for four abundant Neotropical species with high potential for restoration: Guazuma ulmifolia, Trichospermum mexicanuum, Inga vera and Ochroma pyramidale. The best biomass predictors were diameter at breast height and at the base, which generated allometric relations with r² 0.90 or higher. Based on these relations, average biomass accumulation in two-year-old monocultures of Inga, Ochroma, Trichospermum and Guazuma were calculated at 6.60, 30.80, 47.62 and 48.12 Mg ha-1. Restoration plantations with the last two species are a potentially efficient strategy to reduce atmospheric carbon. The high inter-site and inter-species variability, partly related to differences in survival and growth, indicate the need for multi-site experimental designs in otder to generalize the results of biomass estimation.

  6. ESTUDIO CINÉTICO DEL PROCESO DE DEVOLATILIZACIÓN DE BIOMASA LIGNOCELULÓSICA MEDIANTE ANÁLISIS TERMOGRAVIMÉTRICO PARA TAMAÑOS DE PARTÍCULA DE 2 A 19 mm / KYNETIC STUDY OF THE BIOMASS DEVOLATILIZATION PROCESS IN PARTICLES sizes between 2- 19 mm BY MEANS OF THERMOGRAVIMETRIC ANALYSIS

    Scientific Electronic Library Online (English)

    ANDRÉS, MELGAR; David, Borge; Juan F., Pérez.

    2008-07-01

    Full Text Available Con el objetivo de proporcionar herramientas que mejoren el diseño de los sistemas de gasificación/combustión de biomasa, y los modelos cinético-químicos de dichos procesos, se presenta un estudio de la cinética química asociada al proceso de devolatilización de biomasa mediante pruebas de termograv [...] imetría utilizando tamaños de partícula que varían de 2 a 19 mm, y tasas de calentamiento de 10, 15 y 20 K/min. El desarrollo de este trabajo se justifica debido a que no hay resultados disponibles en la bibliografía que estudien tamaños superiores a 1 mm. Mediante el ajuste de los puntos experimentales utilizando un modelo de primer orden se determinan los parámetros de las constantes cinéticas (forma de Arrhenius). El estudio muestra que la energía de activación es directamente proporcional a la tasa de calentamiento y al tamaño de partícula, se comprueba que el proceso de descomposición térmica de la biomasa se da a temperaturas más altas con el aumento del tamaño de las partículas, debido a la importancia que toman los procesos de transferencia calor y masa. Los parámetros cinéticos calculados pueden ser utilizados en los modelos dimensionales del proceso de gasificación-combustión de biomasa, considerando el tamaño de las partículas intrínseco en la cinética. Abstract in english A chemical kinetic study of the biomass devolatilization process is presented looking for to improve the design of the biomass gasification-combustion systems and their kinetics (dimensional) models. The study is carried out by means of thermogravimetric tests, with biomass size between 2 - 19 mm, a [...] nd with the heating rate of 10, 15 and 20 K/min. This work is developed because there are not available results on the literature with biomass size bigger than 1 mm. The experimental points are fitted by means of a first order model, to calculate the parameters of the kinetic constants (Arrhenius form). The activation energy is proportional to the heating rate and the biomass size. It can be seen that the thermal decomposition of the biomass is gotten at higher temperatures; due to the transports phenomena (heat and mass) are more relevant. The kinetic parameters calculated can be used in the biomass gasification-combustion dimensional models, in function of the biomass size, to improve the simulation results.

  7. BIOMASA AÉREA Y CONTENIDO DE CARBONO DEL SALADILLO (Caraipa llanorum) EN PUERTO CARREÑO, VICHADA, COLOMBIA / Aerial biomass and carbon content of Saladillo (Caraipa llanorum) in Puerto Carreño, Vichada, Colombia

    Scientific Electronic Library Online (English)

    Román, Ospina Montealegre; Andrés Felipe, Ardila Fernández; Diego Fernando, Martínez Bolaños; Edwin, Rengifo Canizales.

    2013-12-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish RESUMEN Se determinaron el volumen, la biomasa y el contenido de carbono aéreo por hectárea para los bosques de Saladillo (Caraipa llanorum) en la finca Canapro Forestal, en el municipio de Puerto Carreño, del departamento de Vichada; para ello, se realizó un muestreo destructivo de 30 individuos pa [...] ra ajustar un modelo con el fin de estimar estas variables; fue necesario determinar el peso fresco de los diferentes compartimentos de cada árbol, así como el volumen de cada fuste; luego, se obtuvieron submuestras de la biomasa del fuste, las ramas y las hojas por árbol para llevar al laboratorio y obtener la densidad y el contenido de carbono de la madera. El inventario forestal reportó una densidad de 342 árboles por hectárea de C. llanorum con dap ?10 cm, que representan un volumen de 37,4 m3·ha-1, correspondientes a 26,3 t·ha-1 de carbono; la densidad reportada para la madera fue de 0,65 kg·m3-1 y su contenido de carbono, de 52,96 %. Para estimar la biomasa aérea de la especie, la ecuación que mejor ajuste pre sentó fue BT=e-9.47559+2.56189*ln(dap) y el factor de expansión de biomasa reportado fue de 1,52; para estimar el carbono, la ecuación ajustada fue C=e-10.2355 + 2.59771*ln(dap). Abstract in english ABSTRACT We determined the volume, biomass and carbon content per hectare for aerial forest Saladillo (Caraipa llanorum) at the Canapro Forestry farm (Puerto Carreño, Vichada), by destructively sampling 30 individuals. In order to fit a model to estimate variables, it was necessary to determine the [...] fresh weight of the different components of each tree, and the volume of each stem. Subsamples were taken to determine the biomass of the stem, branches and leaves of each tree in order to obtain the density and carbon content of the wood. Forest inventory reported a density of 342 trees per hectare of C. llanorum with dbh ? 10 cm. This represents a volume of 37,4 m³ corresponding to 26,3 t·ha-1 of carbon. The wood density was 0,65 kg·m3-1 and the carbon content 52,96 %. To estimate the biomass of the species a best fit equation was used BT=e-9.47559+2.56189*ln(dap) with a biomass expansion factor of 1,52 reported for estimating the carbon balanced equation, C= e-10.2355 + 2.59771*ln(dbh).

  8. Influência do índice de massa corpórea, porcentagem de gordura corporal e idade da menarca sobre a capacidade aeróbia (VO2 máx) de alunas do ensino fundamental / Influence of body mass index, body fat percentage and age at menarche on aerobic capacity (VO2 max) of elementary school female students

    Scientific Electronic Library Online (English)

    Tiago Leoni, Capel; Mauro, Vaisberg; Maita Poli de, Araujo; Roberta Foster Leonidas de, Paiva; Juliana de Melo Batista dos, Santos; Zsuzsanna Ilona Katalin de Jarmy-Di, Bella.

    2014-02-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Identificar e relacionar a composição corporal, baseada na porcentagem de gordura corporal e o índice de massa corpórea (IMC), e a idade da menarca, com a capacidade aeróbia, utilizando-se os valores de VO2 máximo indireto, de estudantes do segundo ciclo do ensino fundamental. MÉTODOS [...] : Foram avaliadas 197 meninas com média de idade de 13,0±1,2 anos, estudantes de duas escolas estaduais de Atibaia-SP. Para estimar a porcentagem de gordura corporal, foi realizada uma avaliação de dobras cutâneas utilizando-se o protocolo de Slaughter para meninas adolescentes. Já o índice de massa corpórea (IMC), medido em quilogramas por metro quadrado (kg/m2), seguiu as recomendações da Organização Mundial da Saúde (OMS). Para a avaliação aeróbia, foi utilizado o teste de corrida proposto por Léger, determinando o volume de oxigênio máximo de forma indireta (VO2 máx). Para a análise estatística, foi utilizada a regressão linear de Pearson, o teste t de Student e a análise multivariada. RESULTADOS: 22,3% das meninas apresentaram sobrepeso e 3,5% obesidade, de acordo com o IMC. Na amostra estudada, 140 (71,1%) adolescentes relataram a ocorrência de menarca. A média de idade da menarca foi de 12,0±1,0 anos. A média de idade de menarca para o grupo com IMC normal foi significativamente maior (12,2±0,9 anos) do que nas estudantes com sobrepeso ou obesidade (11,6±1,0 anos). A média do VO2 máx indireto foi de 39,6±3,7 mL/kg/min, variando de 30,3 a 50,5 mL/kg/min. O avanço da idade cronológica e a precocidade da menarca correlacionaram-se positivamente com os menores valores de VO2 máx. CONCLUSÕES: Meninas com maiores valores de IMC e percentual de gordura corporal apresentaram menores valores de VO2 máx. A precocidade da menarca e o avanço da idade cronológica foram os fatores mais importantes para a redução da capacidade aeróbia. A idade da menarca foi mais elevada em meninas com IMC adequado quando comparadas com as meninas com sobrepeso ou obesidade. Abstract in english PURPOSE: To identify and relate body fat percentage (skin fold measures), body mass index (BMI) and age at menarcheto aerobic capacity using the indirect VO2 maximum value (VO2 max) of girls in the second cycle of primary school. METHODS: A total of 197 girls aged 13.0±1.2 years on average, st [...] udents from two public schools in the city of Atibaia in São Paulo, were evaluated. Anthropometric evaluation of skin folds was performed using the Slaughter protocol for teenage girls, and BMI (kg/m2) was based on "Z score" (graphic of percentile) according to WHO recommendations. The Léger protocol was used to determine VO2 max. Pearson linear regression and the Student t-test were used for statistical analysis. RESULTS: 22.3% of the girls were overweight and 3.5% were obese according to the classification proposed by the WHO; 140 (71.1%) girls reported menarche. The average age at menarche was 12.0±1.0 years and was significantly higher in the group with normal BMI (12.2±0.9 years) than in the overweight or obese groups (11.6±1.0 years). The average indirect VO2 max value was 39.6±3.7 mL/kg/min, ranging from 30.3 to 50.5 mL/kg/min. The advance of chronological age and early age at menarche were positively correlated with lower VO2 max values. CONCLUSIONS: This study showed that 25.8% of the girls had aBMI value above WHO recommendations. Girls with higher BMI and higher body fat percentage had lower VO2 max. The earlier age at menarche and the advance of chronological age were the most important factors for the reduction of aerobic capacity. The ageat menarche was higher in girls with adequate BMI compared tooverweight or obese girls.

  9. Template-free synthesis of BiVO4 nanostructures: II. Relationship between various microstructures for monoclinic BiVO4 and their photocatalytic activity for the degradation of rhodamine B under visible light

    International Nuclear Information System (INIS)

    The shape-controlled synthesis of nanostructured materials has opened up new possibilities to improve their physical and chemical properties. In this work, new types of monoclinic structured BiVO4 with complex morphologies, namely flowerlike, disclike, tubelike and platelike shapes, have been synthesized in a binary green solvent (water and ethanol) through controlling reaction conditions such as solvent, pH value, concentration of precursors and reaction temperature. The morphology of BiVO4 can transform from three-dimensional (3D) flowerlike superstructures and hexagonal-prismatic nanotubes to two-dimensional (2D) platelike and disclike structures. UV-vis absorption spectra show that all of the prepared nano- and microstructures can respond to visible light and the optical properties of BiVO4 samples are relevant to their structures. More importantly, the photocatalytic activities of various BiVO4 samples are strongly dependent on their morphology for the degradation of rhodamine B (RhB) under visible-light irradiation. The 2D (disclike and platelike) BiVO4 demonstrates better photocatalytic activity than 3D and bulk BiVO4. Among the nano- and microstructures, the nanoplate BiVO4 exhibit the highest photocatalytic activity for degradation of organic pollutants. Additionally, it is found that the different microstructure of BiVO4 leads to the different degradation route for organithe different degradation route for organic compounds of RhB. The reasons for the differences in the photocatalytic behavior for these BiVO4 nanostructures are further discussed. The relationship between the microstructure and the photocatalytic activity for BiVO4 may give clues for the preparation of photocatalysts with high activity based on material morphology design. Moreover, the prepared 2D BiVO4 can be a good photocatalyst used in environmental pollution control.

  10. VoIP: A Corporate Governance Approach to Avoid the Risk of Civil Liability

    Directory of Open Access Journals (Sweden)

    Mariana Gerber

    2013-10-01

    Full Text Available Since the deregulation of Voice over Internet Protocol (VoIP in 2005, many South African organizations are now attempting to leverage its cost saving and competitive values. However it has been recently cited that VoIP is one of the greatest new risks to business. This risk is cited to increase Information Security insurance premiums in the near future. Due to the dynamic nature of the technology, regulatory and legislative concerns such as lawful interception of communications and privacy may also contribute to business risk. VoIP consists of both direct communications (voice conversation and indirect communications (voice mails, emails and instant messaging. Due to this dual nature, complying with regulations such as the Regulation of Interception of Communications and Provision of Communication-Related Information Act (RICA should be considered. In order to leverage value from the VoIP implementation, an executive or SME owner should look to implement the technology with knowledge of the potential risk of civil liability. This is further highlighted by the King III Report which makes the Directors and CEO of an organisation ultimately responsible for IT Governance and Information Security Governance. The report goes further to say, any new technology, such as VoIP, should comply with all South African legislation and regulations. This responsibility encourages the practice of both due care and due diligence. However, recent trends exercised by Information Security professionals, responsible for drafting Information Security policies, often neglect the regulatory requirements and choose to only implement international best practices with no considerations to the risk of civil liability. Although these best practice frameworks may inadvertently comply with existing local legislation, a chance of an oversight is a possibility. Oversights may not only result in criminal sanctions but also civil action due to losses or damages suffered by a third party. Using both the identified regulations and relevant international best practices one may attempt to ensure good Governance with regards to VoIP’s dual nature. The aim is to aid executives and SME owners in mitigating the risk of civil liability to better leverage VoIP’s value by utilizing the proposed VoIP: Civil Liability Risk Table. This should aid in the exercise of due care and due diligence when implementing VoIP as a means of conducting business communication.

  11. VoIP: A Corporate Governance Approach to Avoid the Risk of Civil Liability

    Directory of Open Access Journals (Sweden)

    Tian Gerber

    2013-09-01

    Full Text Available Since the deregulation of Voice over Internet Protocol (VoIP in 2005, many South African organizations are now attempting to leverage its cost saving and competitive values. However it has been recently cited that VoIP is one of the greatest new risks to business. This risk is cited to increase Information Security insurance premiums in the near future. Due to the dynamic nature of the technology, regulatory and legislative concerns such as lawful interception of communications and privacy may also contribute to business risk. VoIP consists of both direct communications (voice conversation and indirect communications (voice mails, emails and instant messaging. Due to this dual nature, complying with regulations such as the Regulation of Interception of Communications and Provision of Communication-Related Information Act (RICA should be considered. In order to leverage value from the VoIP implementation, an executive or SME owner should look to implement the technology with knowledge of the potential risk of civil liability. This is further highlighted by the King III Report which makes the Directors and CEO of an organisation ultimately responsible for IT Governance and Information Security Governance.  The report goes further to say, any new technology, such as VoIP, should comply with all South African legislation and regulations. This responsibility encourages the practice of both due care and due diligence. However, recent trends exercised by Information Security professionals, responsible for drafting Information Security policies, often neglect the regulatory requirements and choose to only implement international best practices with no considerations to the risk of civil liability. Although these best practice frameworks may inadvertently comply with existing local legislation, a chance of an oversight is a possibility. Oversights may not only result in criminal sanctions but also civil action due to losses or damages suffered by a third party. Using both the identified regulations and relevant international best practices one may attempt to ensure good Governance with regards to VoIP’s dual nature. The aim is to aid executives and SME owners in mitigating the risk of civil liability to better leverage VoIP’s value by utilizing the proposed VoIP: Civil Liability Risk Table. This should aid in the exercise of due care and due diligence when implementing VoIP as a means of conducting business communication.

  12. Highly oriented VO2 thin films prepared by sol-gel deposition method

    CERN Document Server

    Chae, B G; Yun, S J; Kim, B J; Lee, Y W; Youn, D H; Kang, K Y; Chae, Byung-Gyu; Kim, Hyun-Tak; Yun, Sun-Jin; Kim, Bong-Jun; Lee, Yong-Wook; Youn, Doo-Hyeb; Kang, Kwang-Yong

    2005-01-01

    Highly oriented VO2 thin films were grown on sapphire substrates by the sol-gel method that includes a low pressure annealing in an oxygen atmosphere. This reduction process effectively promotes the formation of the VO2 phase over a relatively wide range of pressures below 100 mTorr and temperatures above 400oC. X-ray diffraction analysis showed that as-deposited films crystallize directly to the VO2 phase without passing through intermediate phases. VO2 films have been found to be with [100]- and [010]-preferred orientations on Al2O3(1012) and Al2O3(1010) substrates, respectively. Both films undergo a metal-insulator transition with an abrupt change in resistance, with different transition behaviors observed for the differently oriented films. For the [010]-oriented VO2 films a larger change in resistance of 1.2x10^4 and a lower transition temperature are found compared to the values obtained for the [100]-oriented films.

  13. Photocatalytic Property of Eu/BiVO4 Photocatalyst by Citric Acid Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    WANG Min, LIU Qiong, SUN Ya-Jie, CHE Yin-Sheng, JIANG Chen-Zhi

    2013-02-01

    Full Text Available Eu3+-doped BiVO4 photocatalyst was synthesized by complexing Sol-Gel method using citric acid as chelate, and characterized with X-ray photoelectron spectroscope(XPS, X-ray diffraction(XRD, scanning electron microscope(SEM, specific surface area (BET and UV-Vis diffuse reflectance spectroscope(DRS. The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO solution under visible light. It revealed that pure BiVO4 and all the Eu3+ doped samples were monoclinic phase and no peaks of any other phases or impurities were detected. It was also found that doping Eu3+ increased the amount of V4+ and oxygen vacancies. In addition, the light absorption edges of Eu3+ doped BiVO4 had extended a red shift compared with that of pure BiVO4. However, Eu3+ doping had little influence on morphology and specific surface area. The appropriate amount of Eu3+ doping could signifcantly increase the photocatalytic activity and the highest photocatalytic degradation rate was about 95% when the Eu3+ doping amount was 0.2%, which was more 62% than that of pure BiVO4 under 50 min visible light irridation.

  14. High quality, hybrid-MBE growth of SrVO3 thin films

    Science.gov (United States)

    Moyer, Jarrett; Eaton, Craig; Engel-Herbert, Roman

    2013-03-01

    Vanadium-based transition metal oxides are an intriguing class of materials to study due to the metal-to-insulator (MIT) transitions that arise in many of the binary oxides (i.e. VO2, V2O3, V2O5). The perovskite SrVO3 is metallic in bulk; however, it is possible to induce an MIT by modulating the bandwidth through strain or dimensional confinement. A mandatory requirement for controlling the electronic phase transition properties in material systems with strong correlation is the growth of high quality, stoichiometric thin films. This is demonstrated here with the growth of SrVO3 on LSAT (001) substrates using a hybrid-MBE technique, where the Sr is evaporated from an effusion cell and the V is provided through the metal-organic precursor vanadium oxo-tri-isopropoxide (VTIP). The structural properties of films with varying VTIP:Sr ratios are characterized by RHEED, XRD, AFM and TEM. These measurements demonstrate that SrVO3 can be grown with excellent structural quality, atomically flat surfaces and rocking curves of the same width as the substrate, accomplishing a necessary first step in controlling the MIT in SrVO3.

  15. Photochemical Charge Separation at Particle Interfaces: The n-BiVO4-p-Silicon System.

    Science.gov (United States)

    Yang, Yuxin; Wang, Jiarui; Zhao, Jing; Nail, Benjamin A; Yuan, Xing; Guo, Yihang; Osterloh, Frank E

    2015-03-18

    The charge transfer properties of interfaces are central to the function of photovoltaic and photoelectrochemical cells and photocatalysts. Here we employ surface photovoltage spectroscopy (SPS) to study photochemical charge transfer at a p-silicon/n-BiVO4 particle interface. Particle films of BiVO4 on an aluminum-doped p-silicon wafer were obtained by drop-coating particle suspensions followed by thermal annealing at 353 K. Photochemical charge separation of the films was probed as a function of layer thickness and illumination intensity, and in the presence of methanol as a sacrificial electron donor. Electron injection from the BiVO4 into the p-silicon is clearly observed to occur and to result in a maximum photovoltage of 150 mV for a 1650 nm thick film under 0.3 mW cm(-2) illumination at 3.5 eV. This establishes the BiVO4-p-Si interface as a tandem-like junction. Charge separation in the BiVO4 film is limited by light absorption and by slow electron transport to the Si interface, based on time-dependent SPS measurements. These problems need to be overcome in functional tandem devices for photoelectrochemical water oxidation. PMID:25700019

  16. Methods of determining equilibrium concentration of VO2+ in aquequs solutions of molybdovanadophosphoric heteropolyacids

    International Nuclear Information System (INIS)

    Ways of determination of equilibrium concentration of VO2+ in solutions of molybdovanadophosphoric heteropoliacids Hsub(3+n)PMosub(12-n)Vsub(n)Osub(40) (HPA-n) at n=2-6 using the methods of laser combinational light scattering spectroscopy, spectrophotometry, kinetic measurements, chemical analysis are considered. HPA concentration varied in the limits 0.001-0.15 mol/l, pH of solution varied from 3.5 to zero. Corresponding information for different pH of the medium and HPA concentrations is presented. Within the limits of every method accuracy the results of VO2+ determination well agree. Combination of the methods permitted to determine with reliability not only VO2+ concentration but to describe the processes proceeding in HPA solutions. In pH range 3-0 HPA-n transforms into HPA-m (1 2+, H2PO4-, at that, [VO2+]=12[H2PO4-]. HPA-1 is the most stable one, it decomposes into H2PO4-, VO2+, and MoO22+ in a strongly acid medium

  17. Control of the Metal-Insulator Transition in VO2 Epitaxial Film by Modifying Carrier Density.

    Science.gov (United States)

    Chen, F H; Fan, L L; Chen, S; Liao, G M; Chen, Y L; Wu, P; Song, Li; Zou, C W; Wu, Z Y

    2015-04-01

    External controlling the phase transition behavior of vanadium dioxide is important to realize its practical applications as energy-efficient electronic devices. Because of its relatively high phase transition temperature of 68 °C, the central challenge for VO2-based electronics, lies in finding an energy efficient way, to modulate the phase transition in a reversible and reproducible manner. In this work, we report an experimental realization of p-n heterojunctions by growing VO2 film on p-type GaN substrate. By adding the bias voltage on the p-n junction, the metal-insulator transition behavior of VO2 film can be changed continuously. It is demonstrated that the phase transition of VO2 film is closely associated with the carrier distribution within the space charge region, which can be directly controlled by the bias voltage. Our findings offer novel opportunities for modulating the phase transition of VO2 film in a reversible way as well as extending the concept of electric-field modulation on other phase transition materials. PMID:25751594

  18. Science with the Virtual Observatory: the AstroGrid VO Desktop

    CERN Document Server

    Tedds, Jonathan A

    2009-01-01

    We introduce a general range of science drivers for using the Virtual Observatory (VO) and identify some common aspects to these as well as the advantages of VO data access. We then illustrate the use of existing VO tools to tackle multi wavelength science problems. We demonstrate the ease of multi mission data access using the VOExplorer resource browser, as provided by AstroGrid (http://www.astrogrid.org) and show how to pass the various results into any VO enabled tool such as TopCat for catalogue correlation. VOExplorer offers a powerful data-centric visualisation for browsing and filtering the entire VO registry using an iTunes type interface. This allows the user to bookmark their own personalised lists of resources and to run tasks on the selected resources as desired. We introduce an example of how more advanced querying can be performed to access existing X-ray cluster of galaxies catalogues and then select extended only X-ray sources as candidate clusters of galaxies in the 2XMMi catalogue. Finally ...

  19. Nanoporous thermochromic VO(2) films with low optical constants, enhanced luminous transmittance and thermochromic properties.

    Science.gov (United States)

    Kang, Litao; Gao, Yanfeng; Luo, Hongjie; Chen, Zhang; Du, Jin; Zhang, Zongtao

    2011-02-01

    Nanoporous thermochromic VO(2) films with low optical constants and tunable thicknesses have been prepared by polymer-assisted deposition. The film porosity and thickness change the interference relationship of light reflected from the film-substrate and the air-film interfaces, strongly influencing the optical properties of these VO(2) films. Our optimized single-layered VO(2) films exhibit high integrated luminous transmittance (T(lum,l) = 43.3%, T(lum,h) = 39.9%) and solar modulation (?T(sol) = 14.1%, from T(sol,l) = 42.9% to T(sol,h) = 28.8%), which are comparable to those of five-layered TiO(2)/VO(2)/TiO(2)/VO(2)/TiO(2) films (T(lum,l) = 45%, T(lum,h) = 42% and ?T(sol) = 12%, from T(sol,l) = 52% to T(sol,h) = 40%, from Phys. Status Solidi A2009, 206, 2155-2160.). Optical calculations suggest that the performance could be further improved by increasing the porosity. PMID:21268632

  20. A REGRESSION EQUATION FOR THE ESTIMATION OF VO2MAX IN NEPALESE MALE ADULTS

    Directory of Open Access Journals (Sweden)

    Pinaki Chatterjee

    2010-05-01

    Full Text Available The purpose of the study was to validate the applicability of 20-meter multi stage shuttle run test in Nepalese male College students. 40 Nepalese students were recruited for the study. Direct estimation of cardiorespiratory endurance (VO2max comprised treadmill exercise followed by expired gas analysis by scholander micro-gas analyzer whereas VO2max was indirectly predicted by the 20-meter multistage shuttle run test. The difference between the mean (SD VO2max values of direct measurement (VO2max = 39.29+/-1.98 ml/kg/min and 20-meter multi stage shuttle run test (SPVO2max = 39.20+/-2.27 ml/kg/min was statistically insignificant (p >0.10. Limits of agreement analysis also suggest that the 20-m multistage shuttle run test can be applied for use with the studied population. The results suggest that the application of the present form of 20-meter multistage shuttle run test be justified in the studied population. For better prediction of VO2max a new equation has been developed based on present data.

  1. FTIR study on VO2 defect in fast neutron irradiated czochralski silicon

    International Nuclear Information System (INIS)

    The vacancy-dioxygen complex (VO2) is one of the main defects formed in fast neutron irradiated CZ-Si during annealing in the temperature range 400-500 degree C. In this defect, two oxygen atoms share a vacancy, each of which is bonded to two silicon neighbors. With the increase of the 889 cm-1 (VO2), two infrared absorption bands at 919.6 and 1006 cm-1 will arise in neutron irradiated CZ-Si after annealed in the temperature range 300-500 degree C. IR vibrational bands at 919.6 and 1006 cm-1 can be assigned to the metastable defect (O-V-O) that is composed of a VO (A center) and a neighboring interstitial oxygen (Oi) atom. By prolonging the annealing time from 2h up to 10 h or increasing the annealing temperature, the metastable defect (O-V-O) will be converted into VO2. During annealing in the temperature range 400-500 degree C, the main defects formed in the high dose (1019) neutron irradiated CZ-Si is the multi-vacancy type of defects and the formation of the VO2 will be depressed. (authors)

  2. Zn3(VO4)2 prepared by magnetron sputtering: microstructure and optical property

    Science.gov (United States)

    Mukhtar, Surayya; Zou, Chongwen; Gao, Wei

    2013-12-01

    Zinc vanadium oxide Zn3(VO4)2 has been prepared by means of DC magnetron sputtering and subsequent post heat treatment. The samples were synthesized via two routes: dual-target co-sputtering of ZnO and V2O5 or the ordinal deposition of V2O5 and ZnO thin layers. The obtained precursors were then annealed in oxygen atmosphere from 500 to 550 °C to form the Zn3(VO4)2 compound. Morphology and composition of the samples have been investigated by means of scanning electron microscope and energy-dispersive X-ray spectroscopy. X-ray diffraction pattern shows the presence of ?-Zn3(VO4)2, ZnO and vanadium oxide in the annealed ZnO-V2O5 samples. Pure V2O5 with two distinct phases, ? and ? phases, is found for the samples annealed at 500 °C. Room temperature photoluminescence properties have been studied, and the annealed samples exhibit excellent light emission in the visible region centred at 528 nm from Zn3(VO4)2 compound. The light emission from Zn3(VO4)2 is discussed based on charge transfer and Frank-Condon principles.

  3. Comparaciones entre cuatro métodos de estimación de biomasa en praderas de festuca alta / Comparison of four biomass estimation methods in Tall Fescue pastures

    Scientific Electronic Library Online (English)

    Isaías, López-Guerrero; Joseph P., Fontenot; Teresa Beatriz, García-Peniche.

    2011-06-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish En los experimentos de pastoreo, la masa de forraje es una medida necesaria para calcular otros atributos de la pradera, como son su crecimiento, utilización, y descomposición. El problema es que esa biomasa no se puede medir en estudios a gran escala, sólo se puede estimar usando algún método de mu [...] estreo. Cuando se submuestrea, el método de corte directo (MD) ha sido aceptado como el más confiable, siempre y cuando se tomen suficientes muestras. Existen, sin embargo, métodos indirectos que pueden ser más fáciles, baratos y rápidos que el MD. En consecuencia, el objetivo de este trabajo fue comparar el MD con tres métodos indirectos para estimar la masa de forraje: el medidor de pasto por capacitancia (MC), el plato medidor de pastos (PM) y la estimación visual (EV). El experimento fue conducido en seis potreros de festuca alta durante los años 2002 y 2003. Se desarrollaron ecuaciones de calibración para cada método indirecto y en cada fecha de muestreo, usando regresión lineal simple. Los coeficientes de determinación para las ecuaciones de calibración con todos los datos fueron de 0.686, 0.751, y 0.862 para MC, PM, y EV, respectivamente. Se encontraron diferencias (P Abstract in english In grazing experiments, forage mass is a necessary measurement for estimating other grassland attributes such as growth, utilization, and decomposition. The predicament is that forage biomass cannot be measured in large scale grazing trials; it can only be estimated through some sampling technique. [...] When subsampling, the herbage cutting method (HCM) has been accepted as the most reliable, provided an adequate number of samples are taken. There are, however, some indirect methods that may be easier, less expensive, and faster than clipping. For that reason, the purpose of the present study was to compare HCM with three indirect methods for estimating the forage mass: pasture capacitance meter (PCM), pasture plate meter (PPM) and visual estimation (VE). The experiment was carried out on six tall fescue paddocks during the 2002 and 2003 growing seasons. Calibration equations were put together for each indirect method for every sampling date using the simple linear regression technique. Coefficients of determination, for the pooled calibration equations, were 0.686, 0.751, and 0.862 for PCM, PMP, and VE, respectively. Significant differences (P

  4. Optimización del medio de cultivo QBP para la producción de biomasa del consorcio BIOYAF / Optimization of culture media QBP to the production of biomass of consortium BIOYAF

    Scientific Electronic Library Online (English)

    Yaima, Barrios San Martín; Silvia, Acosta Días; Francisca, González Hernández; Ranyer, Hayes García.

    2014-07-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish La optimización de los medios de cultivo con fines industriales en la mayoría de los casos ha sido efectuada mediante procedimientos empíricos de ensayo y error. Empleando diversos métodos estadísticos es probable que el medio de cultivo original pueda ser optimizado, en muchos casos es posible obte [...] ner un medio que no solo sea más productivo, sino de menor o igual costo que el original. Se optimizó el medio de cultivo QBP para el crecimiento de las cepas del consorcio bacteriano BIOYAF capaz de degradar hidrocarburos del petróleo, empleando un Diseño de Factor Categórico Individual para determinar el tiempo de trabajo, un Diseño Factorial (24) para determinar los rangos de trabajo de concentración de los nutrientes y un Diseño de Superficie de Respuesta para optimizar las concentraciones. Las variables de respuesta de evaluación de los experimentos fueron masa húmeda, masa (UDO), conteo de viables, conductividad, pH y tensión superficial. El tiempo óptimo para el crecimiento de las cepas del consorcio BIOYAF es de seis horas. El medio de cultivo QBP con concentraciones óptimas de fosfato de amonio (3,19 g.L-1), sulfato de magnesio (0,04 g.L-1), levadura (3,77 g.L-1) y sacarosa (47,89 g.L-1) permite que la producción de biomasa aumente de 1,540 UDO a 3,082 UDO. Abstract in english The optimization of culture media with industrial purposes, in most cases, has been made through empirical trial and error procedures. Using different statistical methods original culture media can be optimized, in many cases, is possible to obtain a more productive media, at the same cost as the or [...] iginal one. The culture media QBP was optimized for the growth of the bacterial consortium BIOYAF, which can degrade petroleum hydrocarbons, using a Categorical Individual Factor Design to determine the working time, a Factorial Design (24) to determine working range of elements concentration and a Surface Response Design to optimize the concentrations. The response variables of the experiments used in this work were: wet mass, mass (UDO), viable's count, conductivity, pH and surface tension. The optimal time for growth of the consortium was of six hours. The optimized QBP culture media (ammonium phosphate: 3.19; magnesium sulphate: 0,04; yeast extract : 3,77; sucrose: 47,89) allowed that the biomass' production increases of 1,540 UDO to 3,082 UDO.

  5. Modelo de producción de biomasa en suelos ácidos de raña corregidos con productos calizos Biomass production model for lime amended acid raña-soils

    Directory of Open Access Journals (Sweden)

    E. Villa

    2010-01-01

    Full Text Available Se han realizado unos ensayos de campo de dos años de duración encaminados a la corrección de la acidez de un Typic Palexe­rult, de las formaciones de raña de la mese­ta norte de la provincia de León (España. El cultivo ensayado fue una variedad local de centeno, empleándose como materiales calizos en la enmienda del suelo el yeso, do­lomita, caliza y espumas de azucarería, con dosis de 6000 kg ha-1 de CaCO3 equivalente. Además de la analítica general, se determi­naron las formas de Al solubles y fácilmente intercambiables (Al-CaCl2, además del Al extraído con KCl y con BaCl2. Los modelos de regresión lineal múltiple de la producción total de biomasa demuestran que durante el primer año son el Al-CaCl2, pH y CICE los parámetros más explicativos de la varianza (R² = 0,82. Por el contrario, durante el segundo año de cultivo son el Al-KCl y el porcentaje de saturación de bases las varia­bles más correlacionadas con la producción (R² = 0,80.Field trials were carried out over a pe­riod of two years, aimed at correcting the acidity of a Typic Palexerult in raña for­mations in the northern mesa of León province (Spain. Gypsum, dolomite, limestone and sugar foam waste were em­ployed as liming materials to correct soil acidity, incorporating 6000 kg of CaCO3 equivalent per ha-1, and crop trials were carried out using a local variety of rye. In addition to carrying out a general analy­sis, soluble and easily exchanged forms of A1 were identified (Al-CaCl2, as was A1 extracted using KC1 and BaCl2. Multiple linear regression models for total biomass production show that in the first year, variance (R² = 0.82 was largely ex­plained by the parameters Al-CaCl2, pH and CECE. However, in the second year of crop trials, production was most closely correlated with the variables Al-KCl and base saturation percentage (R² = 0.80.

  6. Modelo de producción de biomasa en suelos ácidos de raña corregidos con productos calizos / Biomass production model for lime amended acid raña-soils

    Scientific Electronic Library Online (English)

    E., Villa; M., Vidal.

    2010-01-01

    Full Text Available SciELO Portugal | Language: Spanish Abstract in spanish Se han realizado unos ensayos de campo de dos años de duración encaminados a la corrección de la acidez de un Typic Palexe­rult, de las formaciones de raña de la mese­ta norte de la provincia de León (España). El cultivo ensayado fue una variedad local de centeno, empleándose como materiales calizos [...] en la enmienda del suelo el yeso, do­lomita, caliza y espumas de azucarería, con dosis de 6000 kg ha-1 de CaCO3 equivalente. Además de la analítica general, se determi­naron las formas de Al solubles y fácilmente intercambiables (Al-CaCl2), además del Al extraído con KCl y con BaCl2. Los modelos de regresión lineal múltiple de la producción total de biomasa demuestran que durante el primer año son el Al-CaCl2, pH y CICE los parámetros más explicativos de la varianza (R² = 0,82). Por el contrario, durante el segundo año de cultivo son el Al-KCl y el porcentaje de saturación de bases las varia­bles más correlacionadas con la producción (R² = 0,80). Abstract in english Field trials were carried out over a pe­riod of two years, aimed at correcting the acidity of a Typic Palexerult in raña for­mations in the northern mesa of León province (Spain). Gypsum, dolomite, limestone and sugar foam waste were em­ployed as liming materials to correct soil acidity, incorporati [...] ng 6000 kg of CaCO3 equivalent per ha-1, and crop trials were carried out using a local variety of rye. In addition to carrying out a general analy­sis, soluble and easily exchanged forms of A1 were identified (Al-CaCl2), as was A1 extracted using KC1 and BaCl2. Multiple linear regression models for total biomass production show that in the first year, variance (R² = 0.82) was largely ex­plained by the parameters Al-CaCl2, pH and CECE. However, in the second year of crop trials, production was most closely correlated with the variables Al-KCl and base saturation percentage (R² = 0.80).

  7. Morphology-dependent photocatalytic removal of NO by hierarchical BiVO{sub 4} microboats and microspheres under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Zhihui, E-mail: jennifer.ai@mail.ccnu.edu.cn [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079 (China); Lee, Shuncheng [Department of Civil and Structural Engineering, Research Center for Environmental Technology and Management, The Hong Kong Polytechnic University, Hong Kong (China)

    2013-09-01

    In this study, hierarchical monoclinic BiVO{sub 4} three-dimensional (3D) superstructures with two kinds of morphologies, namely BiVO{sub 4} microboats and BiVO{sub 4} microspheres, have been controllably synthesized by adjusting reaction time in the template-free hydrothermal process using ethylene glycol as solvent. The nucleation, growth, and self-assembly of the BiVO{sub 4} superstructures could be readily controlled with reaction time, which brought different morphologies to the final product. The as-prepared BiVO{sub 4} superstructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption experimentation, and UV-vis diffuse reflectance spectra (UV-vis DRS). The monoclinic 3D BiVO{sub 4} catalysts are composed of two-dimensional (2D) nanoplates which intercross with each other. Nanoplates were firstly formed by aggregation of primary nanocrystallites and then self-assembly converted to microboats and microspheres via the oriented attachment mechanism. The prepared BiVO{sub 4} 3D catalysts can respond to visible light and their optical and photocatalytic properties are relevant to their morphologies. The BiVO{sub 4} microspheres showed superior photocatalytic activity on removal of gaseous NO compared to the BiVO{sub 4} microboats. The morphology-dependent photocatalytic property of the BiVO{sub 4} superstructures is discussed. This work suggests that the synthesized BiVO{sub 4} micropheres are promising photocatalyst for environmental remediation.

  8. Controlled synthesis of T-shaped BiVO4 and enhanced visible light responsive photocatalytic activity

    International Nuclear Information System (INIS)

    A novel T-shaped BiVO4 microcrystal photocatalyst was successfully synthesized by the hydrothermal method with the aid of a structure-directing surfactant SDBS in the present study. Having received well characterization with the aid of various techniques and the results showed that the SDBS greatly changed the microstructure of BiVO4, which had a unique T shape and belonged to the monoclinic family. The fast exchange dynamics between the surfactants bound to the Bi3+ seed surface and the free VO3? in the solution significantly increase the rate of heterogeneous nucleation. In addition, the photocatalytic activity of the prepared T-shaped BiVO4 was evaluated by the degradation of Methylene Blue solution under visible light irradiation, 17% and 47% higher decolorization rates than the commercial P25 and BiVO4 synthesized without SDBS, respectively. Meanwhile, it has been found that the degradation kinetics of MB fitted the pseudo-first-order kinetics and the T-shaped BiVO4 also displayed high photocatalytic performance for metronidazole degradation. -- Graphical abstract: H2O2 molecules function as electron trapping reagent to react with e? to enhance the photocatalytic degradation efficiency of MB in the BiVO4/H2O2 system under visible light irradiation. Highlights: • T-shaped BiVO4 was synthesized using SDBS as a structure-directing surfactant. • SDBS greatly changed the microstructure of BiVO4. • The T-shaped BiVO4 had a better visible-light photocatalytic activity. • Degradation kinetics of MB by BiVO4 fitted the pseudo-first-order kinetics

  9. Controlled synthesis of T-shaped BiVO{sub 4} and enhanced visible light responsive photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Shuying; Yu, Chongfei; Li, Yukun [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China); Li, Yihui [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Sun, Jianhui, E-mail: sunjh@htu.cn [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China); Geng, Xiaofei [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China)

    2014-03-15

    A novel T-shaped BiVO{sub 4} microcrystal photocatalyst was successfully synthesized by the hydrothermal method with the aid of a structure-directing surfactant SDBS in the present study. Having received well characterization with the aid of various techniques and the results showed that the SDBS greatly changed the microstructure of BiVO{sub 4}, which had a unique T shape and belonged to the monoclinic family. The fast exchange dynamics between the surfactants bound to the Bi{sup 3+} seed surface and the free VO{sub 3}{sup ?} in the solution significantly increase the rate of heterogeneous nucleation. In addition, the photocatalytic activity of the prepared T-shaped BiVO{sub 4} was evaluated by the degradation of Methylene Blue solution under visible light irradiation, 17% and 47% higher decolorization rates than the commercial P25 and BiVO{sub 4} synthesized without SDBS, respectively. Meanwhile, it has been found that the degradation kinetics of MB fitted the pseudo-first-order kinetics and the T-shaped BiVO{sub 4} also displayed high photocatalytic performance for metronidazole degradation. -- Graphical abstract: H{sub 2}O{sub 2} molecules function as electron trapping reagent to react with e{sup ?} to enhance the photocatalytic degradation efficiency of MB in the BiVO{sub 4}/H{sub 2}O{sub 2} system under visible light irradiation. Highlights: • T-shaped BiVO{sub 4} was synthesized using SDBS as a structure-directing surfactant. • SDBS greatly changed the microstructure of BiVO{sub 4}. • The T-shaped BiVO{sub 4} had a better visible-light photocatalytic activity. • Degradation kinetics of MB by BiVO{sub 4} fitted the pseudo-first-order kinetics.

  10. Proactive QoS Enhancement Technique for Efficient VoIP Performance over Wireless LAN and Cognitive Radio Network

    Directory of Open Access Journals (Sweden)

    Tamal Chakraborty

    2012-12-01

    Full Text Available VoIP over Wireless LANs is greatly affected bypath-loss, RF interference and other sources of signalattenuation in addition to network congestion. The primaryfactors involved in effective real-time communication,namely delay and loss, must be within certain controlledlimits in such a scenario. Wireless LAN Access Points must,therefore, act in tune with the codecs to ensure high qualityof the ongoing VoIP sessions. Further deployment of VoIPin opportunistic communication medium like cognitiveradio network requires thorough analysis of the factorsinvolved in design and implementation of such networksalong with modifications in VoIP parameters. In this paper,the various codec parameters are analyzed with respect towireless LAN access points. Thereafter, an optimizationalgorithm is developed based on proactive strategy to keeploss and latency within tolerable limits. The proposedalgorithm is hence implemented in the SIP enabled test-bedto provide optimum Voice over IP (VoIP performance. Theproactive strategy is further applied to study VoIPperformance over cognitive radio networks. A simulationmodel is developed for VoIP transmission in cognitive radionetworks with two scenarios where the primary and thesecondary user involve in VoIP transmission respectively.For each scenario, extensive analysis of both VoIP and CRNparameters is performed and an algorithm is proposedbased on codecs and active queues to ensure highthroughput of VoIP traffic with enhanced QoS. Resultsverify significant performance improvement in VoIP callquality under both wireless LAN and cognitive radionetwork environment. Simulation and measured resultshave also been included.

  11. Specificity of V·O2MAX and the ventilatory threshold in free swimming and cycle ergometry: comparison between triathletes and swimmers

    OpenAIRE

    Roels, B.; Schmitt, L.; Libicz, S.; Bentley, D.; Richalet, J.; Millet, G.

    2005-01-01

    Objectives: To compare maximal heart rate (HRMAX), maximal oxygen consumption (V·O2MAX), and the ventilatory threshold (VT; %V·O2MAX) during cycle ergometry and free swimming between swimmers and triathletes.

  12. Efecto de dos frecuencias y alturas de corte en la producción de biomasa de morera (Morus alba Linn.) / Effect of two pruning frequencies and heights on the biomass production of mulberry (Morus alba Linn.)

    Scientific Electronic Library Online (English)

    Yolai, Noda; Giraldo, Martín; Rey, Machado; Danny E, García; María G, Medina.

    2007-10-01

    Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish Con el objetivo de determinar el potencial de rendimiento de la morera variedad Tigreada, se estudiaron dos alturas (50 y 100 cm) y dos frecuencias de corte (45 y 90 días), mediante un diseño totalmente aleatorizado en la Estación Experimental de Pastos y Forrajes "Indio Hatuey", Cuba. Se evaluaron [...] las variables agronómicas: rendimiento de materia seca de la biomasa total (BT), rendimiento de materia seca de la biomasa comestible (BC), rendimiento de materia seca de las hojas (BH) y rendimiento de materia seca de los tallos tiernos (BTT) en el periodo lluvioso (PLL) y poco lluvioso (PPLL) en un año de explotación del cultivo. El efecto de la interacción altura x frecuencia fue significativo (P Abstract in english With the objective to determine the potential yield of the mulberry variety Tigreada, two pruning heights (50 and 100 cm) and two cutting frequencies (45 and 90 days) were studied, by using of a completely randomized design at the Experimental Station of Pastures and Forages "Indio Hatuey", Cuba. Th [...] e agronomic variables: dry matter yield of total biomass (TB), dry matter yield of edible biomass (EB), dry matter yield of leaves biomass (LB), and dry matter yield of fresh stems biomass (FSB) were evaluated in the rainy (RS) and dry seasons (DS) in a year of exploitation of the crop. The height by frequency interaction was significant (P

  13. Palomar-QUEST: A case study in designing sky surveys in the VO era

    CERN Document Server

    Graham, M J; Djorgovski, S G; Mahabal, A A; Baltay, C; Rabinowitz, D; Bauer, A; Snyder, J; Morgan, N; Andrews, P; Szalay, A S; Brunner, R J; Musser, J; Graham, Matthew J.; Williams, Roy; Mahabal, Ashish; Baltay, Charles; Rabinowitz, Dave; Bauer, Anne; Snyder, Jeff; Morgan, Nick; Andrews, Peter; Szalay, Alexander S.; Brunner, Robert J.; Musser, Jim

    2004-01-01

    The advent of wide-area multicolour synoptic sky surveys is leading to data sets unprecedented in size, complexity and data throughput. VO technology offers a way to exploit these to the full but requires changes in design philosophy. The Palomar-QUEST survey is a major new survey being undertaken by Caltech, Yale, JPL and Indiana University to repeatedly observe 1/3 of the sky (~15000 sq. deg. between -27 < Dec <27 in seven passbands. Utilising the 48-inch Oschin Schmidt Telescope at the Palomar Observatory with the 112-CCD QUEST camera covering the full 4 x 4 sq. deg. field of view, it will generate \\~1TB of data per month. In this paper, we review the design of QUEST as a VO resource, a federated data set and an exemplar of VO standards.

  14. Microwave ultrasonic attenuation above the Jahn-Teller phase transition in TmVO4

    International Nuclear Information System (INIS)

    Ultrasonic attenuation at 9 GHz has been studied as a function of magnetic field at 4.2K in TmVO4, which undergoes a Jahn-Teller phase transition at 2.15 K. The ultrasonic attenuation is shown to be caused by the relaxation properties of the Tm3+ electronic states, which are coupled by the Jahn-Teller interaction to the acoustic phonons. The observed dependence of attenuation on magnetic field is well described by a linear response function theory. Values for the electronic pseudo-spin damping parameters are GAMMA1/2? = (1.8 +- 0.5) GHz and GAMMA2/2? = (2.5 +- 0.7) GHz in pure TmVO4 and GAMMA1/2? approximately equal to 9 GHz for the dilute salt Tmsub(0.82)Lusub(0.18)VO4. (author)

  15. Epitaxial growth and characterization of CaVO3 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Liberati, Marco; Chopdekar, R.V.; Mehta, V.; Arenholz, E.; Suzuki, Y.

    2009-01-09

    Epitaxial thin films of CaVO{sub 3} were synthesized on SrTiO{sub 3}, LaAlO{sub 3} and (La{sub 0.27}Sr{sub 0.73})(Al{sub 0.65}Ta{sub 0.35})O{sub 3} substrates by pulsed laser deposition. All CaVO{sub 3} films, independent of epitaxial strain, exhibit metallic and Pauli paramagnetic behavior as CaVO{sub 3} single crystals. X-ray absorption measurements confirmed the 4+ valence state for Vanadium ions. With prolonged air exposure, an increasing amount of V{sup 3+} is detected and is attributed to oxygen loss in the near surface region of the films.

  16. ErVO4-II, a Scheelite-type high-pressure modification of erbium orthovanadate

    International Nuclear Information System (INIS)

    Mr=282.20, tetragonal, I41/a, a=5.003 (1), c=11.143 (2) A, V=278.91 A3, Z=4, Dx=6.72 Mg m-3, ?(Mo K?)=0.71073 A, ?=1.58 mm-1, F(000)=492, T=298 K. The structure was refined to R=0.035, wR=0.037 for 478 absorption-corrected observed reflections. The high-pressure modification ErVO4-II, prepared at 40 kbar and 1525 K, crystallizes with the scheelite-type structure and comprises VO4 tetrahedra [V-O=1.722 (3) A] and ErO8 dodecahedra [Er-O=2.333 (3) (4x), 2.368 (3) A (4x)]. (orig.)

  17. COMPARATIVE STUDY ON THE ASSESSMENT OF VO2MAX BY ERGOSPIROMETRIE OR FIELD TEST

    Directory of Open Access Journals (Sweden)

    Trofin Petrut Florin

    2013-12-01

    Full Text Available The maximum oxygen consumption (VO2max can be considered an important indicator of cardio-respiratory aptitude in endurance effort, being used both in predicting performance in sports and in personal training plans. The research paper carries out a study aimed at evaluating VO2max by ergospirometry compared to its assessment by using a field test. This study used for ergospirometry Cosmed FittMate Pro equipment with direct gas exchange analyzer during a progressive effort protocol on cycle ergometer while the field test used the VAMEVAL testing. New female subjects, aged between 20 and 25 years have conducted both tests at an interval of 72 hours. The recorded outcomes do not indicate statistically significant differences, which proves the validity of the VO2max testing, both in the field testing and ergospirometry.

  18. Instantaneous band gap collapse in photoexcited monoclinic VO2 due to photocarrier doping.

    Science.gov (United States)

    Wegkamp, Daniel; Herzog, Marc; Xian, Lede; Gatti, Matteo; Cudazzo, Pierluigi; McGahan, Christina L; Marvel, Robert E; Haglund, Richard F; Rubio, Angel; Wolf, Martin; Stähler, Julia

    2014-11-21

    Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic VO2 quasi-instantaneously into a metal. Thereby, we exclude an 80 fs structural bottleneck for the photoinduced electronic phase transition of VO2. First-principles many-body perturbation theory calculations reveal a high sensitivity of the VO2 band gap to variations of the dynamically screened Coulomb interaction, supporting a fully electronically driven isostructural insulator-to-metal transition. We thus conclude that the ultrafast band structure renormalization is caused by photoexcitation of carriers from localized V 3d valence states, strongly changing the screening before significant hot-carrier relaxation or ionic motion has occurred. PMID:25479507

  19. Synthèse et structure cristalline de K 3Nb 6VO 19

    Science.gov (United States)

    Haddad, Amor; Jouini, Tahar

    1996-07-01

    K 3Nb 6VO 19, Mr = 1029.67, crystallizes in the hexagonal crystal system, space group P-62 mand Z= 4. The lattice parameters are a= 9.114(1) Å and c= 24.044(6) Å; V= 1729.6(5) Å 3; Dx = 3.954 Mg·m -3. The crystal structure was refined from 601 independent reflections. The final Rindex and weighted Rwindex are 0.0311 and 0.0638, respectively. K 3Nb 6VO 19is constituted by chains of NbO 6octahedra, parallel to the c axis, linked together by pooling corners with VO 4tetrahedra and NbO 6octahedra, to form a three-dimensional framework having interconnected tunnels, parallel to the a axis, where the potassium ions are located. This structure is similar to that of Ba 6Nb 14Si 4O 47(13).

  20. Theoretical investigation of the optical and EPR parameters for VO2+ion in some complexes

    International Nuclear Information System (INIS)

    The molecular orbital coefficients and the EPR parameters of trisodium citrate dihydrate, sodium hydrogen oxalate monohydrate, potassium d-gluconate monohydrate and L-Alanine vanadyl complexes are calculated theoretically. Two d-d transition spectra and EPR parameters for the VO2+ complex are calculated theoretically by using crystal-field theory. The calculated g and A paramaters have indicated that paramagnetic center is axially symmetric. Having the relations of g??g??ge and A??A? for VO2+ ions, it can be concluded that VO2+ ions are located in distorted octahedral sites (C4v) elongated along the z-axis and the ground state of the paramagnetic electron is dxy. - Highlights: ? The EPR parameters and molecular orbital coefficients are calculated theoretically. ? The g and A values of all complexes are found to be nearly axially symmetric. ? The ground state of the paramagnetic electron is dxy.

  1. Influence of Security Mechanisms on the Quality of Service of VoIP

    Science.gov (United States)

    Backs, Peter; Pohlmann, Norbert

    While Voice over IP (VoIP) is advancing rapidly in the telecommunications market, the interest to protect the data transmitted by this new service is also rising. However, in contrast to other internet services such as email or HTTP, VoIP is real-time media, and therefore must meet a special requirement referred to as Quality-of-Service to provide a comfortable flow of speech. Speech quality is worsened when transmitted over the network due to delays in transmission or loss of packets. Often, voice quality is at a level that even prevents comprehensive dialog. Therefore, an administrator who is to setup a VoIP infrastructure might consider avoiding additional decreases in voice quality resulting from security mechanisms, and might leave internet telephony unprotected as a result. The inspiration for this paper is to illustrate that security mechanisms have negligible impact on speech quality and should in fact be encouraged.

  2. Influence of nitrate supplementation on VO? kinetics and endurance of elite cyclists.

    Science.gov (United States)

    Christensen, P M; Nyberg, M; Bangsbo, J

    2013-02-01

    The present study examined if an elevated nitrate intake would improve VO(2) kinetics, endurance, and repeated sprint capacity in elite endurance athletes. Ten highly trained cyclists (72 ± 4 mL O(2) /kg/min, mean?±?standard deviation) underwent testing for VO(2) kinetics (3 × 6 min at 298 ± 28 W), endurance (120 min preload followed by a 400-kcal time trial), and repeated sprint capacity (6 × 20 s sprints, recovery 100 s) during two 6-day periods in randomized order with a daily ingestion of either 0.5 L beetroot (BR) juice to increase nitrate levels or a 0.5 L placebo (PLA) drink with blackcurrant juice. Plasma NOx (nitrate + nitrite) levels were higher (P juice had no effect on VO(2) kinetics and performance in elite cyclists. PMID:23020760

  3. From V2O5 foam to VO2(B) nanoneedles

    International Nuclear Information System (INIS)

    Nanoneedles B phase VO2 with high crystallinity was hydrothermally synthesized from the foam prepared by mixing V2O5, aniline and H2O in the mol ratio 1:1:258. The samples have been characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction and thermal analysis. Regularly sized VO2(B) nanoneedles have the following dimensions: 0.5-5 ?m in length and about 50 nm in average diameter. According to transmission electron microscopy investigations, the V2O5 crystals resulting from the foam exhibit nanoparticles sizes between 50 and 100 nm. This way of synthesis provides a new simple and elegant route to elaborate the vanadium dioxide VO2(B) nanoneedles and V2O5 nanoparticles under soft conditions

  4. Negative capacitance switching via VO2 band gap engineering driven by electric field

    Science.gov (United States)

    He, Xinfeng; Xu, Jing; Xu, Xiaofeng; Gu, Congcong; Chen, Fei; Wu, Binhe; Wang, Chunrui; Xing, Huaizhong; Chen, Xiaoshuang; Chu, Junhao

    2015-03-01

    We report the negative capacitance behavior of an energy band gap modulation quantum well with a sandwich VO2 layer structure. The phase transition is probed by measuring its capacitance. With the help of theoretical calculations, it shows that the negative capacitance changes of the quantum well device come from VO2 band gap by conti