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Sample records for na biomasa vo

  1. PRODUCCIÓN DE PROTEÍNA Y BIOMASA PROBIÓTICA DE Lactobacillus casei LIOFILIZADAS A PARTIR DE SUERO DE LECHE DE CABRA

    OpenAIRE

    E. J. Aguirre-Ezkauriatza; Ramírez-Medrano, A.; Aguilar-Yáñez, J. M.; Álvarez, M. M.

    2009-01-01

    En este trabajo se documenta la factibilidad técnica de obtención de dos productos de valor agregado a partir de suero de leche de cabra: (a) proteína liofilizada y (b) biomasa probiótica liofilizada de Lactobacillus casei. Se presentan resultados de experimentos de ultrafiltración de suero de leche de cabra (SLC), del cual se retiene proteína con una alta relación proteína/lactosa. En su forma liofilizada, esta proteína presentó características de solubilidad superiores a productos comercial...

  2. Crystal structure and spectroscopic properties of Na2K6(VO)(2)(SO4)7

    DEFF Research Database (Denmark)

    Karydis, D.A.; Boghosian, S.; Nielsen, Kurt; Eriksen, Kim Michael; Fehrmann, Rasmus

    2002-01-01

    Red-brown crystals of a new mixed alkali oxo sulfato vanadium(V) compound Na2K6(VO)(2)(SO4)(7), suitable for X-ray determination, have been obtained from the catalytically important binary molten salt system M2S2O7-V2O5 (M = 80% K and 20% Na). By slow cooling of a mixture with the mole fraction X......-V2O5 = 0.24 from 325 degreesC, i.e., just below the liquidus temperature, to the solidus temperature of around 300 degreesC, a dark reddish amorphous phase was obtained containing crystals of the earlier described V(V)-V(IV) mixed valence compound K-6(VO)(4)(SO4)(8) and Na2K6-(VO)(2)(SO4...... neighboring VO3+ groups. The length of the S-O bonds in the S-O-V bridges of the two unidentately coordinated sulfato groups are 1.551(6) Angstrom and 1.568(6) Angstrom, respectively, which are unusually long compared to our earlier measurements of sulfate groups in other V(111), V(IV), and V(V) compounds....

  3. 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.

  4. High-temperature Raman spectroscopic study of vanadoborate Na3VO2B6O11

    Science.gov (United States)

    Ji, Zhang; De-Ming, Zhang; Qing-Li, Zhang; Shao-Tang, Yin

    2016-03-01

    Raman spectra of a vanadoborate (Na3VO2B6O11) crystal from room temperature up to the melting point have been recorded. The main internal vibrational modes of the crystal have been assigned. It was found that all the Raman bands exhibit decreases in frequency and the widths of the Raman bands increase with the increase of temperature. However, no phase transition was observed under 525 °C. The micro-structure of its melt was studied by quantum chemistry ab initio calculation. The continuous three-dimensional network of the crystal collapsed and transformed into VO4 and VBO6 clusters during the melting process with an isomerization reaction from four-coordinated boron to a three-coordinated species. Project supported by the National Natural Science Foundation of China (Grant Nos. 51302268 and 51102239) and the Natural Science Foundation of Anhui Province, China (Grant No. KJ2015A339).

  5. 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)

  6. AgNa(VO2F2)2: a trioxovanadium fluoride with unconventional electrochemical properties.

    Science.gov (United States)

    Donakowski, Martin D; Görne, Arno; Vaughey, John T; Poeppelmeier, Kenneth R

    2013-07-01

    We present structural and electrochemical analyses of a new double-wolframite compound: AgNa(VO2F2)2 or SSVOF. SSVOF is fully ordered and displays electrochemical characteristics that give insight into electrode design for energy storage beyond lithium-ion chemistries. The compound contains trioxovanadium fluoride octahedra that combine to form one-dimensional chain-like basic building units, characteristic of wolframite (NaWO4). The 1D chains are stacked to create 2D layers; the cations Ag(+) and Na(+) lie between these layers. The vanadium oxide-fluoride octahedra are ordered by the use of cations (Ag(+), Na(+)) that differ in polarizability. In the case of sodium-ion batteries, thermodynamically, the use of a sodium anode introduces a 300 mV loss in overall cell voltage as compared to a lithium anode; however, this can be counter-balanced by introduction of fluoride into the framework to raise the reduction potentials via an inductive effect. This allows sodium-ion batteries to have comparable voltages to lithium systems. With SSVOF as a baseline compound, we have identified new materials design rules for emerging sodium-ion systems that do not apply to lithium-ion systems. These strategies can be applied broadly to provide materials of interest for fundamental structural chemistry and appreciable voltages for sodium-ion electrochemistry. PMID:23796147

  7. 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.

  8. 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

  9. Structural, luminescence, and electronic properties of the alkaline metal-strontium cyclotetravanadates M2Sr(VO3)4 (M=Na, K, Rb, Cs)

    International Nuclear Information System (INIS)

    Structural, luminescence, and electronic properties of the family of alkaline metal-strontium cyclotetravanadates M2Sr(VO3)4, M=Na, K, Rb, and Cs have been characterized by means of elemental analyses, x-ray powder diffraction, neutron diffraction, electron diffraction, infrared, Raman, photo, x rays, pulse cathode beam excitation, x-ray photoelectron spectroscopy and band structure calculations. The M2Sr(VO3)4 system have tetragonal structures Na-, K-, Rb-P4/nbm and Cs-P4/mmm, with a=10.63449(4), 10.94106(6), 11.08889(8), 7.9183(3) and c=4.96205(4), 5.31600(4), 5.46682(8), 5.5778(3) A, respectively. The main structural feature of M2Sr(VO3)4 is tetracyclic [V4O12] units. When going from Na2Sr(VO3)4 to Cs2Sr(VO3)4 do the coordination polyhedron around the alkaline metal change continuously from an octahedron to a hexagonal prism and that around the strontium from a square antiprism to a square prism. The hybridized O 2p-V 3d states of tetracyclic [V4O12] units have a dominant influence on the electronic structure of these compounds. All M2Sr(VO3)4 are semiconducting with a decreasing LDA band gap (Ea) from 2.02 for Na2Sr(VO3)4 to 1.56 eV for Cs2Sr(VO3)4

  10. Near-infrared downconversion through host sensitized energy transfer in Yb3+-doped Na2YMg2(VO4)3

    Science.gov (United States)

    Li, Yong; Wei, Xiantao; Chen, Hongmei; Pan, Yan; Ji, Yuexia

    2015-12-01

    Host sensitized near-infrared emitting phosphor Na2YMg2(VO4)3:Yb3+ was fabricated by a sol-gel method. Efficient broad emission is observed under ultraviolet excitation ranging from 240 nm to -400 nm and this luminescence originates from ligand-metal charge transfer of 2p of O2- to 3d of V5+. Under excitation of ultraviolet light in the broad absorption band, intense near-infrared emission of Yb3+ around 974 nm is observed for Yb3+-doped Na2YMg2(VO4)3. Through study of photoluminescence spectra, fluorescence decay curves and concentration-dependent luminescence, mechanism of energy transfer from VO4 group to Yb3+ was proposed to rationalize the downconversion process. This phosphor with performance of ultra-violet to near-infrared downconversion could have potential application in improving efficiency of silicon-based solar cell.

  11. 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, β = 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, β = 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, β = 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.)

  12. Evidence of "new hot spots" from determining the nonlinear optical behavior of materials: mechanistic studies of the vanadium borate crystal, Na3VO2B6O11.

    Science.gov (United States)

    Su, Xin; Yang, Zhihua; Lee, Ming-Hsien; Pan, Shilie; Wang, Ying; Fan, Xiaoyun; Huang, Zhenjun; Zhang, Bingbing

    2015-02-21

    A novel mechanism for the nonlinear optical (NLO) effects of vanadium borate crystals, Na3VO2B6O11 (NVB), with distorted VO4 groups was investigated. A comprehensive analysis of the structure-property relationship was performed by combining the experimental measurements, the electronic structures calculations, the SHG-weighted electron density and the real-space atom-contribution analysis to yield the linear and nonlinear optical properties. The contribution of a (VO4)(3-) anionic group to the second harmonic generation (SHG) response was more pronounced than that of the (BO3)(3-) anionic group, which plays a virtual role in the SHG effects in NVB. The anionic (BO3)(3-) groups make dominant contributions to the birefringence, whereas the contribution of the V(5+) cations to these linear optical effects is negligible. PMID:25609419

  13. 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.

  14. Superior high-rate capability of Na3(VO0.5)2(PO4)2F2 nanoparticles embedded in porous graphene through the pseudocapacitive effect.

    Science.gov (United States)

    Xiang, Xingde; Lu, Qiongqiong; Han, Mo; Chen, Jun

    2016-02-23

    Na3(VO0.5)2(PO4)2F2 nanoparticles embedded in porous graphene have been reported as a superior high-rate cathode material for sodium-ion batteries, exhibiting an excellent electrochemical performance with a high reversible capacity of 100 mA h g(-1) at 1 C, 77 mA h g(-1) at 50 C, and a capacity retention of 73% after 1000 cycles at 50 C. In particular, a significant contribution of the pseudocapacitive effect to the Na-storage capacity has been found for the first time. PMID:26853154

  15. A study of optical properties of Sm{sup 3+} ions in ?-Na{sub 3}Y(VO{sub 4}){sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sobczyk, Marcin, E-mail: marcin.sobczyk@chem.uni.wroc.pl; Szyma?ski, Damian

    2013-10-15

    Single crystals of ?-Sm{sup 3+}:Na{sub 3}Y(VO{sub 4}){sub 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 Sm{sup 3+}-doped title crystals are presented and analyzed in detail. The energy transfer between Sm{sup 3+}Sm{sup 3+} as well as from VO{sub 4}{sup 3?} to Sm{sup 3+} were studied in detail. A JuddOfelt intensity analysis of the absorption (300 K) spectrum has been applied for determination of ?{sub ?} parameters which in turn have been used in calculation of the radiative transition probability factor (A), fluorescence branching ratios (?), natural (radiative) lifetime of the {sup 4}G(4){sub 5/2} level of Sm{sup 3+} and emission cross-section (?{sub em}). For the first time very large lifetimes of the Sm{sup 3+} fluorescence level have been observed. -- Highlights: Single crystals of Sm{sup 3+}-doped ?-Na{sub 3}Y(VO{sub 4}){sub 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 Sm{sup 3+} doped vanadate materials. Sm-doped ?-NYV crystal is a new promising luminescence materials.

  16. Theoretical studies of the optical and EPR spectra for VO^{2+} in Na_3C_6H_5O_7·2H_2O single crystal

    Directory of Open Access Journals (Sweden)

    Ch.-Y. Li

    2015-06-01

    Full Text Available On the basis of the perturbation formulas for a d^1 configuration ion in a tetragonal crystal field, the three optical absorption bands and electron paramagnetic resonance (EPR parameters (g factors g_i and hyperfine structure constants A_i for i = || and ⊥, respectively of VO^{2+} in Na_3C_6H_5O_7·2H_2O (TSCD single crystals were studied using the perturbation theory method. By simulating the calculated optical and EPR spectra to the observed values, local structure parameters and negative signs of the hyperfine structure constants A_i of the octahedral (VO_6^{8-} cluster in TSCD single crystal can be obtained.

  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

    Directory of Open Access Journals (Sweden)

    Fabrizio Caputo

    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 ciclistas, 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.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. New chemical route for the synthesis of ?-Na(0.33)V?O? and its fully reversible Li intercalation.

    Science.gov (United States)

    Kim, Jae-Kwang; Senthilkumar, B; Sahgong, Sun Hye; Kim, Jung-Hyun; Chi, Miaofang; Kim, Youngsik

    2015-04-01

    To obtain good electrochemical performance and thermal stability of rechargeable batteries, various cathode materials have been explored including NaVS2, ?-Na(0.33)V2O5, and Li(x)V2O5. In particular, Li(x)V2O5 has attracted attention as a cathode material in Li-ion batteries owing to its large theoretical capacity, but its stable electrochemical cycling (i.e., reversibility) still remains as a challenge and strongly depends on its synthesis methods. In this study, we prepared the Li(x)V2O5 from electrochemical ion exchange of ?-Na(0.33)V2O5, which is obtained by chemical conversion of NaVS2 in air at high temperatures. Crystal structure and particle morphology of ?-Na(0.33)V2O5 are characterized by using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, in combination with electrochemical data, suggest that Na ions are extracted from ?-Na(0.33)V2O5 without irreversible structural collapse and replaced with Li ions during the following intercalation (i.e., charging) process. The thus obtained Li(x)V2O5 delivers a high discharge capacity of 295 mAh g(-1), which corresponds to x = 2, with crystal structural stability in the voltage range of 1.5-4.0 V versus. Li, as evidenced by its good cycling performance and high Coulombic efficiency (under 0.1 mA cm(-2)) at room temperature. Furthermore, the ion-exchanged Li(x)V2O5 from ?-Na(0.33)V2O5 shows stable electrochemical behavior without structural collapse, even at a case of deep discharge to 1.5 V versus Li. PMID:25768692

  19. Polymorphism of NaVO2F2: a P2₁/c superstructure with pseudosymmetry of P2₁/m in the subcell.

    Science.gov (United States)

    Yu, Zi-Qun; Wang, Jing-Quan; Huang, Ya-Xi; Botis, Sanda M; Pan, Yuanming; Mi, Jin-Xiao

    2015-06-01

    The ADDSYM routine in the program PLATON [Spek (2015). Acta Cryst. C71, 9-18] has helped researchers to avoid structures of (metal-)organic compounds being reported in an unnecessarily low symmetry space group. However, determination of the correct space group may get more complicated in cases of pseudosymmetric inorganic compounds. One example is NaVO2F2, which was reported [Crosnier-Lopez et al. (1994). Eur. J. Solid State Inorg. Chem. 31, 957-965] in the acentric space group P2₁ based on properties but flagged by ADDSYM as (pseudo)centrosymmetric P2₁/m within default distance tolerances. Herein a systematic investigation reveals that NaVO2F2 exists in at least four polymorphs: P2₁, (I), P2₁/m, (II), P2₁/c, (III), and one or more low-temperature ones. The new centrosymmetric modification, (III), with the space group P2₁/c has a similar atomic packing geometry to phase (I), except for having a doubled c axis. The double-cell of phase (III) arises from atomic shifts from the glide plane c at (x, ¼, z). With increasing temperature, the number of observed reflections decreases. The odd l reflections gradually become weaker and, correspondingly, all atoms shift towards the glide plane, resulting in a gradual second-order transformation of (III) into high-temperature phase (II) (P2₁/m) at below 493 K. At least one first-order enantiotropic phase transition was observed below 139 K from both the single-crystal X-ray diffraction and the differential scanning calorimetry analyses. Periodic first-principles calculations within density functional theory show that both P2₁/c superstructure (III) and P2₁ substructure (I) are more stable than P2₁/m structure (II), and that P2₁/c superstructure (III) is more stable that P2₁ substructure (I). PMID:26044323

  20. VoIP Security

    OpenAIRE

    Fontanini, Piero

    2008-01-01

    VOIP or Voice Over Internet Protocol is a common term for phone service over IP based networks. There are much information about VoIP and some of how VoIP can be secured. There is however no standard for VoIP and no general solution for VoIP Security. The security in VoIP systems today are often non existing or in best case weak and often based on proprietary solutions. This master thesis investigates threats to VoIP system and describes existing alternatives for securing VoIP as it is today....

  1. 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

    OpenAIRE

    Fabrizio Caputo; Camila Coelho Greco; Benedito Sérgio Denadai

    2005-01-01

    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 ciclistas, 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 ...

  2. Three-dimensional framework of uranium-centered polyhedra with non-intersecting channels in the uranyl oxy-vanadates A2(UO2)3(VO4)2O (A=Li, Na)

    International Nuclear Information System (INIS)

    The uranyl vanadates A2(UO2)3(VO4)2O (A=Li, Na) have been synthesized by solid-state reaction and the structure of the Li compound was solved from single-crystal X-ray diffraction. The crystal structure is built from ?1[UO5]4- chains of edge-shared U(2)O7 pentagonal bipyramids alternatively parallel to a-vector- and b-vector-axis and further connected together to form a three-dimensional (3-D) arrangement. The perpendicular chains are hung on both sides of a sheet ?2[(UO2)(VO4)2]4- parallel to (001), formed by U(1)O6 square bipyramids connected by VO4 tetrahedra, and derived from the autunite-type sheet. The resulting 3-D framework creates non-intersecting channels running down the a-vector- and b-vector-axis formed by empty face-shared oxygen octahedra, the Li+ ions are displaced from the center of the channels and occupy the middle of one edge of the common face. The peculiar position of the Li+ ion together with the full occupancy explain the low conductivity of Li2(UO2)3(VO4)2O compared with that of Na(UO2)4(VO4)3 containing the same type of channels half occupied by Na+ ions in the octahedral sites. Crystallographic data for Li2(UO2)3(VO4)2O: tetragonal, space group I41/amd, a=7.3303(5)A, c=24.653(3)A, V=1324.7(2)A3, Z=4, ?mes=5.32(2)g/cm3, ?cal=5.36(3)g/cm3, full-matrix least-squares refinement basis on F2 yielded, R1=0.032, wR2=0.085 for 37 refined parameters with 364 independent reflections with I>=2?(I)

  3. A phase-transfer assisted solvo-thermal strategy for low-temperature synthesis of Na3(VO1-xPO4)2F1+2x cathodes for sodium-ion batteries.

    Science.gov (United States)

    Zhao, Junmei; Mu, Linqin; Qi, Yuruo; Hu, Yong-Sheng; Liu, Huizhou; Dai, Sheng

    2015-04-28

    We demonstrate that a series of high-performance cathode materials, sodium vanadium polyanionic compounds, Na3(VO1-xPO4)2F1+2x (x = 0, 0.5 and 1), can be synthesized by a phase-transfer assisted solvo-thermal strategy at a rather low temperature (80-140 °C) in one simple step, exhibiting a high Na storage capacity of ca. 120 mA h g(-1) and excellent cycling performance. This study makes a significant step to extend this strategy to the synthesis of functional materials from simple binary to complex multicomponent compounds. PMID:25812049

  4. PRETRATAMIENTOS DE LA CELULOSA Y BIOMASA PARA LA SACARIFICACIN

    Directory of Open Access Journals (Sweden)

    ANDERSON GUARNIZO FRANCO

    2009-01-01

    Full Text Available La biomasa celulsica se ha vuelto un producto interesante para ser aprovechada como materia prima en la fabricacin de biocombustibles, especialmente el etanol. El paso crtico en su conversin a etanol, implica la degradacin de los polisacridos a azcares fermentables, en un proceso denominado sacarificacin. La celulosa, el componente principal de la biomasa, es un polisacrido de difcil degradacin en condiciones de tratamiento moderadas. Las investigaciones ms 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 ms fcil degradacin a azcares fermentables. El presente artculo resume los resultados ms sobresalientes, sin ser exhaustivos, de los pretaratimentos de la celulosa y la biomasa para su conversin a productos fermentables por la ruta etanlica.

  5. RELACIÓN BIOMASA DE RAÍZ/BIOMASA TOTAL DE SOJA (Glycine max EN DOS SISTEMAS DE LABRANZA

    Directory of Open Access Journals (Sweden)

    M\\u00F3nica Beatriz Barrios

    2014-01-01

    Full Text Available La soja es el principal cultivo en Argentina debido a su adaptación a los suelos, la incorporación de tecnología con el empleo de la siembra directa y el precio del mercado internacional. Las propiedades físicas, químicas y biológicas de cada suelo se ven modificadas por el tipo de sistema de laboreo empleado. El entorno generado por la labranza altera el crecimiento y el equilibrio funcional de los cultivos herbáceos. En el año 2006, se instaló un ensayo en el Partido de Ezeiza (Pampa Ondulada, con el objetivo de evaluar los efectos del sistema de laboreo en el equilibrio funcional entre biomasa de raíces/biomasa total en soja (Glycine max durante la campaña 2012/2013. Se utilizó un diseño de bloques completos al azar con dos tratamientos que consistieron en: labranza convencional (LC y siembra directa (SD, con cuatro repeticiones. Se midió: peso de biomasa aérea, área foliar, rendimiento en grano, peso de raíces de 0-10 y 10-20 cm de profundidad, y se calculó biomasa total y la relación biomasa de raíces/biomasa total. El peso de raíces se determinó con el método del cilindro, el área foliar con el paquete estadístico Iproplus y el rendimiento con el cuadrado de corte. Los datos obtenidos fueron sometidos a análisis de varianza y las medias de los tratamientos fueron comparadas según Tukey (P < 0.05. El efecto del sistema de labranza generó diferentes respuestas en función de la variable evaluada y la fecha de muestreo. LC resultó significativamente superior (P < 0.05 respecto a SD en biomasa total y biomasa aérea en las etapas fenológicas R3 y R5; biomasa de raíces en R1 y R3; IAF en R2, R3 y R5. El rendimiento en grano fue mayor en LC respecto de SD, sin embargo el sistema de labranza no afectó la relación biomasa de raíz/biomasa total.

  6. ESTIMACIN DE BIOMASA AREA 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 produccin de biomasa area en cultivos utilizando sensores remotos se realizaron anlisis de la produccin de biomasa e informacin espectral en cinco cultivos medidos en campo, durante una campaa de muestreo en el Valle del Yaqui, Sonora. La informacin espectral fue procesada hasta la obtencin del ndice de vegetacin iso-suelo (IVIS. Los anlisis multitemporales muestran un comportamiento similar entre el desarrollo de los cultivos y el valor del IVIS, por lo que se obtuvo una relacin lineal entre ellos. De manera similar fueron analizados el ndice de cosecha y su relacin con el IVIS. Los resultados mostraron que el IVIS es un ndice adecuado para la estimacin de biomasa y rendimiento en cultivos.

  7. Efeito do tempo de intervalo da amostra ventilatória na variabilidade do consumo máximo de oxigênio (VO2 máx em jogadores de futebol profissional

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Santos Silva

    1999-04-01

    Full Text Available 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 < 0,05 somente quando se comparou a resposta instantânea respiração-a-respiração (breath-by-breath em relação aos outros intervalos de tempos analisados (10, 20, 30, 40, 50 e 60 segundos, respectivamente. Concluindo, durante o exercício de intensidade progressiva, observou-se que o aumento do VO2 foi proporcional à diminuição do intervalo de tempo da coleta ventilatória. O tempo de intervalo maior subestimou esse aumento. Assim, sugere-se que o avaliador utilize intervalos médios na faixa de tempo entre 10 e 60 segundos, pois não foi verificada diferença estatística significante entre esses intervalos.

  8. Utjecaj alkohola na učinak u zadatku sljepoće zbog nepažnje u simuliranoj situaciji vožnje automobila

    OpenAIRE

    Andro Pavuna; Dragutin Ivanec

    2012-01-01

    Akutna konzumacija etilnoga alkohola štetno utječe na brojne vidne funkcije. U ovom smo se istraživanju usredotočili na specifične procese vidne percepcije i pažnje te utjecaj relativno niskih razina alkohola na njih. U istraživanju je sudjelovalo 47 studenata raznih fakulteta Sveučilišta u Zagrebu. Sudionici u eksperimentalnoj skupini (N=22) konzumirali su alkoholni koktel stopostotnoga narančinog soka i votke kako bi dostigli ciljanu razinu alkohola u krvi od 0.8 g/kg, dok su sudionici u ko...

  9. Measurement and modeling for vanadium extraction from the (NaVO3 + H2SO4 + H2O) system by primary amine N1923

    International Nuclear Information System (INIS)

    Highlights: • LLE data for vanadium extraction by primary amine N1923 were obtained. • Three extraction reactions were determined with the slope method. • Thermodynamic equilibrium constants and new Pitzer parameters were regressed. • The prediction performance of this new model was discussed and verified. - Abstract: In this work, the solvent extraction of vanadium by using the primary amine N1923 as extractant was studied. Within different vanadium concentration ranges, the extraction reactions were determined using the slope method at T = 298.15 K based on the vanadium phase diagram. The slopes (the stoichiometric ratio) were determined as 5/3, 1 and 11/3 for (RNH2)5/3H3VO4,(RNH2)H3V3O9 and (RNH2)11/3H6V10O28, respectively. The thermodynamic model was established through regression of the experimental results with the Pitzer equation for both aqueous and organic phases by the General Algebraic Modelling System (GAMS). Three different sets of parameters and chemical equilibrium constants K were determined, which corresponded to the three extraction reactions. The orders of the lnK values are V10>V3>V1 (organic V species), and the distribution coefficients (DV) are DV1>DV3>DV10. The new model was applied to predict the regularities of extraction yield along with different initial conditions, and the results agree well with the experimental values

  10. Modelos matemticos y experimentales sobre el secado de biomasa

    Directory of Open Access Journals (Sweden)

    Jorge Armando Villalba Vidales

    2015-01-01

    Full Text Available El secado de biomasa como proceso previo a la combustin se ha convertido en la actualidad en un factor decisivo para mejorar la eficiencia de dichos procesos en los sectores industrial y residencial. Debido a la creciente importancia de este proceso, los investigadores han desarrollado una gran cantidad de modelos, tanto tericos como experimentales, que buscan predecir la cintica de secado de diferentes tipos de biomasa. Si bien se han logrado grandes avances en el desarrollo de modelos, an no existe un modelo unificado que permita predecir los perfiles de temperatura y humedad para diversos materiales. Dichas dificultades se generan fundamentalmente por la amplia diversidad de biomateriales y las grandes diferencias entre los procesos existentes. El propsito de este artculo es brindar una panormica sobre el estado del arte relativo a modelos, tanto matemticos como experimentales, utilizados en la actualidad para simular procesos de secado de la biomasa. Asimismo, proponer los elementos fundamentales que deber poseer un modelo de secado unificado.

  11. Utjecaj alkohola na učinak u zadatku sljepoće zbog nepažnje u simuliranoj situaciji vožnje automobila

    Directory of Open Access Journals (Sweden)

    Andro Pavuna

    2012-05-01

    Full Text Available Akutna konzumacija etilnoga alkohola štetno utječe na brojne vidne funkcije. U ovom smo se istraživanju usredotočili na specifične procese vidne percepcije i pažnje te utjecaj relativno niskih razina alkohola na njih. U istraživanju je sudjelovalo 47 studenata raznih fakulteta Sveučilišta u Zagrebu. Sudionici u eksperimentalnoj skupini (N=22 konzumirali su alkoholni koktel stopostotnoga narančinog soka i votke kako bi dostigli ciljanu razinu alkohola u krvi od 0.8 g/kg, dok su sudionici u kontrolnoj skupini (N=25 konzumirali placebo – samo narančin sok sa snažnom aromom etilnoga alkohola. Nakon konzumacije pića sudionici su rješavali zadatak vidne percepcije i pažnje koji se sastojao od kratkoga video-isječka koji prikazuje režiranu realnu prometnu situaciju u kojoj jedno vozilo slijedi drugo s centralnim zadatkom brojanja paljenja ''štop'' svjetala na vozilu koje se kreće ispred njega, te percepcije značajnih objekata i detalja iz okoline poput dječjih kolica, djeteta koje prelazi cestu, prometnih zakova i sl. Provedenim je istraživanjem utvrđeno kako sudionici pod utjecajem alkohola postižu statistički značajno slabiji rezultat u zadatku vidne percepcije od sudionika koji nisu pod utjecajem alkohola. Dobiven je umjereni efekt u kumulativnom zadatku vidne percepcije i pažnje, te neznačajan, ali jasan trend štetnoga utjecaja alkohola na pojedine zadatke vidne percepcije i pažnje.

  12. Inhibition protein tyrosine phosphatases by an oxovanadium glutamate complex, Na2[VO(Glu)2(CH3OH)](Glu = glutamate).

    Science.gov (United States)

    Lu, Liping; Wang, Sulian; Zhu, Miaoli; Liu, Zhiwei; Guo, Maolin; Xing, Shu; Fu, Xueqi

    2010-12-01

    The insulin-sensitizing effect of vanadium complexes has been linked to their ability to inhibit protein tyrosine phosphatases (PTPs). Considering that vanadium complexes may exchange in vivo with amino acids, forming in situ vanadium-amino acid complexes, we have synthesized and characterized an oxovanadium glutamate complex, Na(2)[V(IV)O(Glu)(2)(CH(3)OH)]H(2)O (1·H(2)O). The complex showed potent inhibition against four human PTPs (PTP1B, TCPTP, HePTP, and SHP-1) with IC(50) in the 0.21-0.37 μM ranges. Fluorescence titration studies suggest that the complex binds to PTP1B with the formation of a 2:1 complex. Enzyme kinetics analysis using Lineweaver-Burk plots indicates a typical competitive inhibition mode. PMID:20617368

  13. La proteína viral vo6 de rotavirus coinmunoprecipita con hsc70 en células ma104

    OpenAIRE

    Rodríguez, Luz Stella; Guerrero Fonseca, Carlos Arturo

    2011-01-01

    Introducción: los rotavirus son la principal causa de gastroenteritis en niños menores de cinco años. Hasta el momento se desconoce cómo entran estos virus a la célula huésped. La proteína de choque térmico, HSC70 se ha visto involucrada en la entrada del virus, sin embargo no se han relacionado bien todos los sitios de unión entre las proteínas virales del rotavirus y la HSC70.Objetivos: el propósito de este trabajo fue determinar cuáles proteínas virales del rotavirus son responsables de la...

  14. VO Tools variety is the spice of VO life

    Science.gov (United States)

    Osuna, P.

    2009-07-01

    The VO realm allows building of different clients to support the already vast amount of available data, for discovery, analysis, exploitation, mining, etc. The presence of an increasing amount of clients giving service to the VO community has been seen by some to be an added problem to the promotion of the VO. However, in real daily world IT activities, we find fair competing applications here and there, in an ever improving synergy that allows growing and perfecting. In this paper, we make a parallelism of some usual daily IT activities with VO ones, and we emphasize how different applications implement the same standards, both in our daily computer based activities and in the VO, and how this benefits evolution in the field.

  15. On vanadium(5) alcoholates. Behavior of VO2Cl to organic solvents

    International Nuclear Information System (INIS)

    By means of exchange reaction between VOCl3 and NaOR VO(OR)3 (R = Et, i - Pr) is prepared. It is shown that the interaction is complicated by the formation of alkoxychlorides, which are successfully destructed by the introduction of NaOR excess. For the synthesis of VO(OMe)3 the reaction of VO(OEt)3 reesterification by methyl alcohol is used. VO(OR)3 prepared is characterized by the data of IR spectroscopy, mass-spectrometry, X-ray phase analysis. Existence of dimeric molecules in gaseous phase is ascertained. The study of VO2Cl exchange reaction has shown that alcoholates of the series VO2(OR) can not be synthesized by the method, since in case of VO2Cl contact with alcohol alkoxyl is substituted for one oxogroup with the formation of VO(OR)2Cl. Solvolysis processes take place also in case of VO2Cl interaction with other oxygen-containing organic solvents

  16. Estimacin de biomasa por mtodos alomtricos, nutrimentos y carbono en plantaciones de palmito en Costa Rica

    Directory of Open Access Journals (Sweden)

    Adri\\u00E1n Ares

    2002-01-01

    Full Text Available El agroecosistema de palmito (Bactris gasipaes es un sistema de produccin sostenible en los trpicos hmedos. Los mtodos alomtricos permiten predecir la produccin de biomasa en forma no destructiva en cualquier momento y a partir de este dato determinar las fases de crecimiento del cultivo, los componentes de la biomasa y los nutrimentos asociados a cada componente, as como el rendimiento econmico esperado de una plantacin. Los objetivos generales del presente trabajo fueron obtener y validar funciones de prediccin de la biomasa seca y de palmitos producidos en plantaciones comerciales, para correlacionarlos con la biomasa y la produccin comercial de palmitos en las mismas. De esta manera, en varias fincas de la regin Atlntica de Costa Rica se cosech plantas de palmito y se separ sus componentes: follaje, pecolos y tallos. Se utiliz modelos de regresin no lineales para calcular en forma independiente los coeficientes de las ecuaciones y as estimar los componentes de la biomasa y de la biomasa total. El dimetro basal fue una variable ms efectiva para predecir la produccin de biomasa que la altura hasta la hoja candela, la altura total y el nmero de

  17. Právo na internet

    OpenAIRE

    Lexová, Alžběta

    2013-01-01

    The Internet is one of the phenomenons of our time. As of speed and reach it surpasses all media on the world and unlike every other medium it actively engages all people to the process of creating the news. Basic attributes of the Internet make it a power standing above states -- it crosses national borders and doesn't have any direct owner -- and at the same time these attributes make it a power that is practically almost unregulatable. The Internet is regulated on a national level, but the...

  18. VoWiFi Roaming

    OpenAIRE

    Muhammad Ali, Syed

    2006-01-01

    Freedom is human’s natural instinct, which was limited by Ethernet and Fixed Telephony Era. With the emergence of new technologies like wireless fidelity (WiFi) and voice over IP (VoIP) humans once again have freedom of movement; which at the very same time provides enough reasons to change the market dynamics of communication industry. The buzz of Voice over WiFi (VoWiFi) in recent years indicates that VoWiFi is shaping up as the next big challenge to traditional telephony, not only due to c...

  19. BIOMASA DE RACES EN UN BOSQUE TEMPLADO CON Y SIN MANEJO FORESTAL EN HIDALGO, MXICO

    Directory of Open Access Journals (Sweden)

    Numa P. Pavn

    2012-01-01

    Full Text Available Las races son buenos indicadores funcionales del ecosistema ya que constituyen gran parte de la biomasa viva del suelo y ejercen un control sobre los procesos de pedognesis, la produccin de materia orgnica y la dinmica de los nutrientes. En este trabajo se compar la biomasa de races gruesas y finas entre un bosque conservado y un bosque con manejo forestal de corte selectivo. La biomasa promedio de races no difiri significativamente entre sitios (P = 0.185. La biomasa en el bosque con manejo forestal fue de 3.05 Mgha-1 (E. E. = 0.25 y de 3.39 Mgha-1 (E. E. = 0.24 en el bosque conservado. Las races finas ocuparon el mayor porcentaje de la biomasa en ambos tipos de bosque, aunque sus valores no difirieron significativamente entre sitios (P = 0.095. De acuerdo con los resultados, al parecer, el manejo forestal de tipo de corte selectivo mantiene las condiciones ambientales y en particular del suelo, lo que permite contener una biomasa similar a la de un bosque conservado bajo condiciones naturales.

  20. BIOMASA AREA Y FACTORES DE EXPANSIN DE ESPECIES ARBREAS EN BOSQUES DEL SUR DE NUEVO LEN

    Directory of Open Access Journals (Sweden)

    G. Domnguez-Cabrera

    2009-01-01

    Full Text Available El objetivo de este estudio fue la estimacin de biomasa y el clculo de factores de expansin de Pinus pseudostrobus, Pinus teocote, y Quercus spp., en bosques del Sur de Nuevo Len, Mxico. Se derribaron de 8 a 16 rboles por especie, se determin el peso hmedo en campo, se extrajeron muestras para determinar la relacin Peso seco-Peso hmedo (Ps/Ph, con la que se calcul el peso seco total de cada rbol. Se ajustaron modelos de biomasa. La ecuacin que mejor se ajust present la forma y = a(Eb/D +1.3 , donde y es la biomasa area, E exponencial, D dimetro normal, a, b parmetros y 1.3 constante. En todos los casos el coeficiente de determinacin (R2 fue mayor a 0.89 y el error estndar porcentual (Sx% menor a 30.9. Se estim la biomasa por tipo de bosque de acuerdo a los datos de 1,053 rboles obtenidos en las parcelas de muestreo de 400 m2, obtenindose para el bosque de pino 125.333 toneladas de biomasa por hectrea (tBha-1, el de encino-pino 112.593 tBha-1 y el de pino-encino 96.688 tBha-1. Se calcularon factores de expansin de biomasa (Fexp, los valores promedio obtenidos fueron 1,373 para Pinus pseudostrobus, 1,394 para P. teocote y 1,511 para Quercus spp.

  1. VO for Education: Archive Prototype

    Science.gov (United States)

    Ramella, M.; Iafrate, G.; De Marco, M.; Molinaro, M.; Knapic, C.; Smareglia, R.; Cepparo, F.

    2014-05-01

    The number of remote control telescopes dedicated to education is increasing in many countries, leading to correspondingly larger and larger amount of stored educational data that are usually available only to local observers. Here we present the project for a new infrastructure that will allow teachers using educational telescopes to archive their data and easily publish them within the Virtual Observatory (VO) avoiding the complexity of professional tools. Students and teachers anywhere will be able to access these data with obvious benefits for the realization of grander scale collaborative projects. Educational VO data will also be an important resource for teachers not having direct access to any educational telescopes. We will use the educational telescope at our observatory in Trieste as a prototype for the future VO educational data archive resource. The publishing infrastructure will include: user authentication, content and curation validation, data validation and ingestion, VO compliant resource generation. All of these parts will be performed by means of server side applications accessible through a web graphical user interface (web GUI). Apart from user registration, that will be validated by a natural person responsible for the archive (after having verified the reliability of the user and inspected one or more test files), all the subsequent steps will be automated. This means that at the very first data submission through the webGUI, a complete resource including archive and published VO service will be generated, ready to be registered to the VO. The efforts required to the registered user will consist only in describing herself/himself at registration step and submitting the data she/he selects for publishing after each observation sessions. The infrastructure will be file format independent and the underlying data model will use a minimal set of standard VO keywords, some of which will be specific for outreach and education, possibly including VO field identification (astronomy, planetary science, solar physics). The VO published resource description will be suggested such as to allow selective access to educational data by VO aware tools, differentiating them from professional data while treating them with the same procedures, protocols and tools. The whole system will be very flexible, scalable and with the objective to leave as less work as possible to humans.

  2. Integrating existing software toolkits into VO system

    Science.gov (United States)

    Cui, Chenzhou; Zhao, Yong-Heng; Wang, Xiaoqian; Sang, Jian; Luo, Ze

    2004-09-01

    Virtual Observatory (VO) is a collection of interoperating data archives and software tools. Taking advantages of the latest information technologies, it aims to provide a data-intensively online research environment for astronomers all around the world. A large number of high-qualified astronomical software packages and libraries are powerful and easy of use, and have been widely used by astronomers for many years. Integrating those toolkits into the VO system is a necessary and important task for the VO developers. VO architecture greatly depends on Grid and Web services, consequently the general VO integration route is "Java Ready - Grid Ready - VO Ready". In the paper, we discuss the importance of VO integration for existing toolkits and discuss the possible solutions. We introduce two efforts in the field from China-VO project, "gImageMagick" and "Galactic abundance gradients statistical research under grid environment". We also discuss what additional work should be done to convert Grid service to VO service.

  3. Integrating Existing Software Toolkits into VO System

    CERN Document Server

    Cui, C; Wang, X; Sang, J; Luo, Z; Cui, Chenzhou; Zhao, Yongheng; Wang, Xiaoqian; Sang, Jian; Luo, Ze

    2004-01-01

    Virtual Observatory (VO) is a collection of interoperating data archives and software tools. Taking advantages of the latest information technologies, it aims to provide a data-intensively online research environment for astronomers all around the world. A large number of high-qualified astronomical software packages and libraries are powerful and easy of use, and have been widely used by astronomers for many years. Integrating those toolkits into the VO system is a necessary and important task for the VO developers. VO architecture greatly depends on Grid and Web services, consequently the general VO integration route is "Java Ready - Grid Ready - VO Ready". In the paper, we discuss the importance of VO integration for existing toolkits and discuss the possible solutions. We introduce two efforts in the field from China-VO project, "gImageMagick" and " Galactic abundance gradients statistical research under grid environment". We also discuss what additional work should be done to convert Grid service to VO s...

  4. Existencias y tasas de incremento neto de la biomasa y del carbono en bosques primarios y secundarios de Colombia

    OpenAIRE

    Orrego Suaza, Sergio Alonso; Del Valle Arango, Jorge Ignacio

    2002-01-01

    En 33 parcelas permanentes de 1000 m2 (0,1 ha) en bosques primarios y 77 parcelas permanentes de 500 m (0,05 ha) en bosques secundarios, para un área de muestreo de 7,15 ha, se estimaron las existencias de biomasa y del carbono almacenado en los siguientes compartimientos: biomasa aérea, necromasa, biomasa subterránea y suelo. La biomasa aérea total viva en los bosques primarios promedió 246,542 t/ha, representada 92,42% por árboles y arbustos dicotiledóneos, 5,93% en palmas (3,58% la pa...

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

    OpenAIRE

    I. Cano Rodríguez; Pérez, J. A.; Gutiérrez, M; J. L. Gardea

    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 iones de c...

  6. Biomasa acumulada e indicadores de calidad nutritiva en cebadilla chaquea (Bromus auleticus Trinius ex Nees

    Directory of Open Access Journals (Sweden)

    BUSTAMANTE, E.G.R.

    2012-06-01

    Full Text Available Bromus auleticus (cebadilla chaquea es considerada uno de los recursos forrajeros ms promisorios delCono Sur. Presenta variacin entre poblaciones que ha sido determinada para diversos caracteres vegetativos, lo cual podra traducirse en diferencias de produccin y calidad de forraje. El objetivo del presente estudio fue evaluar dos procedencias de cebadilla chaquea (Argentina y Uruguay para biomasa acumulada e indicadores de calidad nutritiva en dos perodos del ao (verano-otoo y otoo-primavera. Se compararon cinco clones uruguayos (U y cinco argentinos (A, dispuestos al azar en surcos distanciados a 1 m entre s, con 10 plantas cada uno. Se determin biomasa acumulada por planta (B y calidad, midiendo Fibra Detergente Neutra (FDN, Protena Bruta (PB y Digestibilidad de la Materia Seca (DMS en dos momentos del ao. En general, la biomasa fue de baja calidad debido al momento en que se realizaron los cortes, lo que limita elalcance de los resultados. Sin embargo, las diferencias observadas entre los clones en este estado de desarrollo podran indicar la existencia de variacin entre genotipos de cebadilla chaquea U y A en biomasa y calidad nutritiva. En biomasa acumulada no se observ efecto significativo de origen. En todas las variablesde calidad evaluadas en verano-otoo, se encontraron diferencias significativas entre orgenes. En otooprimavera, las diferencias entre orgenes 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 encontr coincidencia entre mayor biomasa y mayor calidad.

  7. VoIP over WLAN

    OpenAIRE

    Nikkari, Joni

    2007-01-01

    Tässä opinnäytetyössä tutkitaan VoIP over WLAN -tekniikan mahdollisuuksia nykyaikaisessa käyttöympäristössä, sekä yritysmaailman että kotikäyttäjän näkökulmasta. Toimiakseen VoWLAN tarvitsee kaksi eri tekniikkaa: langattoman lähiverkon sekä WLAN-puhelimen, joka perustuu VoIP-tekniikkaan.; WLAN:ssa tietoliikenne kulkee normaalin kaapeloinnin sijasta radiotaajuuksia käyttämällä. Standardina toimii IEEE 802.11, joka määrittelee WLAN-verkkojen toiminnan. Standardia on kehitetty jatkuvasti, ja si...

  8. Performance of VoIP on HSDPA

    DEFF Research Database (Denmark)

    Wang, Bang; Pedersen, Klaus I.; Kolding, Troels E.; Mogensen, Preben E.

    This paper provides packet scheduler design and performance simulations for running VoIP services over high-speed downlink packet access (HSDPA) in WCDMA. The main challenge of supporting VoIP service on HSDPA is the tight delay requirement combined with the small VoIP packet size. A packet sched...

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

    Directory of Open Access Journals (Sweden)

    Anirebis Martínez 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.

  10. Speaker Recognition in the VoIP Environment

    OpenAIRE

    Remeš, Jan

    2014-01-01

    Tato práce popisuje použití systémů pro rozpoznávání mluvčího v~prostředí VoIP, úspěšnost systému a přístupy k jejímu zlepšení. Popisuje architekturu těchto systémů, metriky pro vyhodnocení jejich úspěšnosti a klíčové komponenty VoIP z hlediska rozpoznávání mluvčího. Je zde popsáno vytvoření simulace VoIP prostředí, úspěšnost systému je vyhodnocena na datech pocházejících z různých druhů VoIP prostředí a výsledky jsou demostrovány. Adaptace a kalibrace systému je provedena a jejich přínosy zh...

  11. Biomasa de Cornops aquaticum (Orthoptera: Acrididae) en humedales del nordeste de Argentina

    OpenAIRE

    Luciana Irene Gallardo; María Celeste Franceschini; Alicia Susana Guadalupe Poi; María Laura De Wysiecki

    2015-01-01

    La estimación de la biomasa en las poblaciones de insectos, es un factor clave para cuantificar los recursos disponibles y los flujos de energía en las redes tróficas de los ecosistemas. Cornops aquaticum es un herbívoro común en las plantas de Eichhornia en los humedales del nordeste de Argentina. Nuestro objetivo fue analizar la variación de su biomasa en relación a las distintas categorías de edades de la población de este acridio, en dos plantas huésped: Eichhornia azurea y Eichhornia cra...

  12. Efeito do tempo de intervalo da amostra ventilatória na variabilidade do consumo máximo de oxigênio (VO2 máx) em jogadores de futebol profissional

    OpenAIRE

    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 Sousa

    1999-01-01

    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 elet...

  13. Estudio terico de la combustin de pellets de biomasa procedente de la caa de azcar

    Directory of Open Access Journals (Sweden)

    David Verdecia Torres

    2012-01-01

    Full Text Available En el siguiente trabajo se examina la cintica qumica de la combustin de pellets de biomasa caera, se obtiene el tiempo de combustin en funcin de la etapa controlante del proceso de combustin segn el modelo de ncleo sin reaccionar, adems se realiza un diseo de experimento para determinar los modelos matemticos tericos para modelar el proceso de combustin.

  14. Almacenamiento de carbono en la biomasa area de una plantacin joven de pinus greggii Engelm.

    Directory of Open Access Journals (Sweden)

    Felcitas Clemencia Pacheco Escalona

    2007-01-01

    Full Text Available Con el objetivo de evaluar el potencial de Pinus greggii Engelm. para almacenar carbono en la biomasa area, se estim la biomasa total area en una muestra de 20 rboles, los cuales se separaron en tallo, ramas y follaje. El estudio se llev a cabo en una plantacin de seis aos de edad establecida en Cuaunepantla, Acaxochitln, Estado de Hidalgo, Mxico. La biomasa seca area promedio fue de 8.0 kg por rbol, de la cual 4.1 kg (51 % se ubic en tallo, 1.9 kg (24 % en ramas y 2.0 kg (25 % en follaje. La productividad primaria neta fue estimada en 5.8 t ha-1 ao-1, para una densidad de 4425 rboles/ha. La concentracin de carbono en tejido vegetal fue de 51 %. Una ecuacin matemtica sencilla (y = 147x + 3288x2 para estimar la biomasa de carbono a partir de la variable combinada de dimetro y altura (D2h explic 89 % de la variacin. Estos resultados muestran que el potencial de almacenamiento de carbono en una plantacin de seis aos de P. greggii Engelm. es relativamente alto, con 17.9 t ha-1, que representa una masa de dixido de carbono equivalente de 65.8 t CO2 ha-1.

  15. Validade preditiva da medida e estimativas do VO2mx no desempenho de Mountain Bikers

    Directory of Open Access Journals (Sweden)

    Fernanda Mainardi

    2015-02-01

    Full Text Available INTRODUO: considerando o racional para a utilizao das equaes preditivas na estimativa do VO2mx em atletas, nenhum estudo estabeleceu sua validade para o desempenho no mountain bike cross-country (XCO. OBJETIVO: comparar diferentes estratgias de determinao do VO2mx, de forma direta ou indireta, para a predio do desempenho em uma prova real e outra simulada. MTODOS: 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 trs sesses experimentais. A primeira visita consistiu na estratificao de risco, avaliao antropomtrica e teste progressivo mximo. Na segunda, foi realizada a prova simulada e, na terceira, foi realizada a competio de XCO. RESULTADOS: a correlao entre a prova simulada e as equaes preditivas do VO2mx de forma absoluta alcanaram relao quase perfeita (r ? 0,9. As correlaes entre a competio real e as estimativas de VO2mx relativizadas massa corporal alcanaram resultados classificados como muito altos (r = 0,7-0,89. As associaes entre a medida direta do VO2mx e a simulao apresentaram uma classificao baixa para valores relativos massa corporal (r = 0,10, IC95% -0,35 a 0,51. Para o desempenho real, a classificao foi moderada (r = 0,48, IC95% 0,009 a 0,78. CONCLUSO: o presente estudo foi o primeiro a demonstrar a validade preditiva das estimativas do VO2mx para o desempenho simulado e real de MTB. Em complemento, confirmou a baixa validade preditiva da medida direta do VO2mx para o mesmo propsito.

  16. Biomasa de Cornops aquaticum (Orthoptera: Acrididae en humedales del nordeste de Argentina

    Directory of Open Access Journals (Sweden)

    Luciana Irene Gallardo

    2015-03-01

    Full Text Available La estimación de la biomasa en las poblaciones de insectos, es un factor clave para cuantificar los recursos disponibles y los flujos de energía en las redes tróficas de los ecosistemas. Cornops aquaticum es un herbívoro común en las plantas de Eichhornia en los humedales del nordeste de Argentina. Nuestro objetivo fue analizar la variación de su biomasa en relación a las distintas categorías de edades de la población de este acridio, en dos plantas huésped: Eichhornia azurea y Eichhornia crassipes. Para ello, se realizaron muestreos estándar de las poblaciones de C. aquaticum con una red entomológica de 70cm de diámetro, en dos humedales con E. azurea y E. crassipes en las provincias de Corrientes y Chaco; además, se obtuvo el peso seco de los individuos (de manera directa e indirecta y, se propuso un modelo de regresión para estimar la biomasa de C. aquaticum de manera indirecta a partir de una medida de dimensión lineal (longitud del fémur posterior. Un total de 2 307 individuos fueron recolectados y separados en distintas categorías de edades; se obtuvo su abundancia y distintas medidas de dimensión lineal. El modelo propuesto fue lnPS=lna+b*lnH (donde PS=peso seco, a y b son constantes y H=longitud del fémur posterior (R²=0.97. Las variaciones en la biomasa de las poblaciones de C. aquaticum se debieron a la abundancia relativa de cada categoría de edad y al peso seco individual de estos acridios. No hubo diferencias significativas entre la biomasa de las poblaciones de C. aquaticum obtenida por los métodos directo e indirecto en las praderas flotantes de E. azurea y E. crassipes. Este modelo facilita el cálculo de la biomasa individual y poblacional de C. aquaticum y acelera el procesamiento de un gran número de muestras. Finalmente, los valores altos de biomasa poblacional e individual de las categorías de edades (especialmente en adultos enfatizan la importancia de C. aquaticum como consumidor y como recurso para los depredadores en las redes alimenticias de las praderas flotantes de Eichhornia.

  17. Biomasa y densidad de dos especies de pastos marinos en el sur de Quintana Roo, México

    OpenAIRE

    Martha Angélica Gutiérrez-Aguirre; María Gabriela de la Fuente-Betancourt; Adrián Cervantes-Martínez

    2000-01-01

    La biomasa y productividad de una comunidad de pastos marinos es útil para determinar el estado ecológico de la costa. Se comparó la biomasa foliar y la densidad de vainas en praderas de Thalassia testudinum Banks & Sol. ex K. D. Koenig, en dos ambientes de la costa del Caribe mexicano (N= 6 cuadrantes/sitio) en Noviembre de 1998. Los valores de vainas y biomasa foliar fueron más bajos en la pradera asociada al manglar, que en la pradera establecida en una laguna arrecifal. Esto probablemente...

  18. Investigation of VoIP and implementation

    OpenAIRE

    Ede, Aghedo

    2011-01-01

    Voice over Internet Protocol (VoIP) is the technology used to transmit conversations digitally over the Internet. VoIP is being adopted globally and changing the landscape of telecommunications for businesses and consumers. This thesis describes the investigation of VoIP and how it compares to traditional phone systems, voice characteristics, implementation challenges, digital voice process, testing and result, the standards organizations promoting the technology, and what this means for us ...

  19. VoIP Technology: Security Issues Analysis

    OpenAIRE

    Lazzez, Amor

    2013-01-01

    Voice over IP (VoIP) is the technology allowing voice and multimedia transmissions as data packets over a private or a public IP network. Thanks to the benefits that it may provide, the VoIP technology is increasingly attracting attention and interest in the industry. Actually, VoIP allows significant benefits for customers and communication services providers such as cost savings, rich media service, phone and service portability, mobility, and the integration with other applications. Nevert...

  20. K vlivu velkomoravského práva na raně středověké české právo

    Czech Academy of Sciences Publication Activity Database

    Havlíková, Lubomíra

    Nitra : Filozofická fakulta Univerzity Konštantína Filozofa - Ústav pre výskum kultúrneho dedičstva Konštantína a Metoda, 2008 - (Michalov, J.; Hetényi, M.; Ivanič, P.; Taneski, Z.), s. 22-32 ISBN 978-80-8094-455-1 Institutional research plan: CEZ:AV0Z90920516 Keywords : Great Moravian law * Czech law * influences Subject RIV: AB - History

  1. Enfermedad pulmonar obstructiva crónica por exposición al humo de biomasa

    Directory of Open Access Journals (Sweden)

    Matías Lopez

    2014-03-01

    Full Text Available 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%. La 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

  2. Enfermedad pulmonar obstructiva crónica por exposición al humo de biomasa

    Directory of Open Access Journals (Sweden)

    Matías Lopez

    2014-01-01

    Full Text Available 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%. La 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

  3. Securing VoIP keeping your VoIP network safe

    CERN Document Server

    (Bud) Bates, Regis J Jr

    2015-01-01

    Securing VoIP: Keeping Your VoIP Network Safe will show you how to take the initiative to prevent hackers from recording and exploiting your company's secrets. Drawing upon years of practical experience and using numerous examples and case studies, technology guru Bud Bates discusses the business realities that necessitate VoIP system security and the threats to VoIP over both wire and wireless networks. He also provides essential guidance on how to conduct system security audits and how to integrate your existing IT security plan with your VoIP system and security plans, helping you prevent

  4. 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(NO335H2O, NaVO3 and Cu(NO323H2O 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 1.02.0 ?m, width of 0.52.0 ?m and thickness of 200300 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 is5.89 102 /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.

  5. VoIP to the Rescue

    Science.gov (United States)

    Milner, Jacob

    2005-01-01

    Voice over Internet Protocol (VoIP) is everywhere. The technology lets users make and receive phone calls over the Internet, transporting voice traffic alongside data traffic such as instant messages (IMs) and e-mail. While the number of consumer customers using VoIP increases every week, the technology is finding its way into K-12 education as…

  6. Graphene quantum dot sensitized leaf-like InVO4/BiVO4 nanostructure: a novel ternary heterostructured QD-RGO/InVO4/BiVO4 composite with enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Lin, Xue; Wang, Yushuang; Zheng, Jia; Liu, Chang; Yang, Yang; Che, Guangbo

    2015-11-28

    Leaf-like InVO4/BiVO4 nanostructures with sizes of 2-5 μm were synthesized by a simple hydrothermal method. Graphene quantum dots (QD-RGO) were then deposited onto the surfaces of the leaf-like InVO4/BiVO4 crystals through a facile deposition-precipitation technique. Under visible light irradiation (λ > 420 nm), the QD-RGO/InVO4/BiVO4 photocatalyst degraded rhodamine B (Rh B) efficiently and displayed a much higher photocatalytic activity than pure BiVO4, InVO4, RGO/InVO4, RGO/BiVO4 or an InVO4/BiVO4 hybrid. The InVO4/BiVO4 photocatalyst with 3 wt% of QD-RGO exhibited the highest photocatalytic efficiency. The quenching effects of different scavengers demonstrated that O2˙(-) played a major role in Rh B degradation. It was elucidated that the excellent photocatalytic activity of QD-RGO/InVO4/BiVO4 for the degradation of Rh B under visible light (λ > 420 nm) can be ascribed to the extended absorption in the visible light region resulting from the QD-RGO loading, the high specific surface area, and the efficient separation of photogenerated electrons and holes through the QD-RGO/InVO4/BiVO4 heterostructure. PMID:26486959

  7. COMPONENŢA AMINOACIZILOR DIN BIOMASA ALGEI CIANOFITE NOSTOC GELATINOSUM (SCHOUSB) ELENK.

    OpenAIRE

    Sergiu DOBROJAN; Irina STRATULAT; Alina TROFIM; Galina DOBROJAN

    2016-01-01

    În articol este analizată componenţa aminoacizilor din biomasa algei cianofite Nostoc gelatinosum (Schousb) Elenk. colectate de pe mediul nutritiv Drew. Din grupa aminoacizilor esenţiali în biomasa algei Nostoc gelatinosum (Schousb) Elenk. se conţine în cantităţi majore leucina (2,142±0,06 mg/100 mg), treonina (1,188±0,02 mg/100 mg) şi valina (1,085±0,03 mg/100 mg). Din aminoacizii neesenţiali predomină acidul aspartic (4,523±0,11 mg/100 mg) şi acidul glutamic (2,774±0,07 mg/100 mg). Alga Nos...

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

    OpenAIRE

    Anirebis Martínez Romero; Angel Leyva Galán

    2014-01-01

    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 nec...

  9. Estudio de la naturaleza qumica de biocrudos obtenidos mediante licuefaccin hidrotrmica de biomasa lignocelulsica

    OpenAIRE

    Castro Vega, Alejandro Amadeus

    2011-01-01

    El agotamiento de los combustibles de origen fsil as como los problemas ambientales asociados con su uso promueve la investigacin y desarrollo de procesos desvinculados de este tipo de energa y recursos para proveer sustentabilidad al desarrollo humano. La conversin hidrotrmica de biomasa es una tecnologa promisoria para obtener combustibles e insumos qumicos, utilizando agua y temperaturas cercanas al punto crtico, que en tales condiciones acta como solvente, catalizador y reactant...

  10. Recuperacin de la biomasa mediante la sucesin 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 informacin sobre el tiempo requerido para recuperar la biomasa area y subterrnea de los primarios. Por lo tanto, establecimos 33 parcelas de 0.1ha entre 550 y 1 700m en bosques secundarios que cubran estadios serales de 3 a 36 aos y estimamos la biomasa de las plantas y de las races gruesas con ecuaciones locales. As como la biomasa de las pasturas y barbechos por cosecha de 54 y 18 parcelas, respectivamente. Tambin se calcul la edad de las parcelas con informantes locales, sensores remotos, C14 y anillos de crecimiento. En cada parcela medimos la biomasa area viva por hectrea (Bav y la de las races gruesas por hectrea (Brg. Modelamos la Bav y Brg en funcin de la edad mediante la ecuacin de von Bertalanfy con asntotas de 247t/ha (Bav y 66t/ha (Brg resultantes de la medicin de 33 parcelas de 0.1ha en los bosques primarios. Con la razn Brg/Bav=f(t estimamos 87 aos para que los bosques secundarios recuperen la Bav existente en los primarios y 217 aos para recuperar la Brg. La tasa mxima de crecimiento instantneo de la Bav fue 6.95t/ha/ao a los 10 aos y la tasa media mxima de crecimiento 6.26t/ha/ao a los 17 aos. La media ponderada de la tasa de crecimiento absoluto de la Bav alcanz 4.57t/ha/ao y la relativa 10% anual. La razn Brg/Bav inicialmente aumenta muy aceleradamente hasta 4-5 aos (25%, luego disminuye hasta 25 aos (18% para luego incrementar hasta 26.7

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

    Directory of Open Access Journals (Sweden)

    Jesús D. Gómez-Díaz

    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.

  12. Antifungalna aktivnost propolisa u ?etiri vrste vo?nih sokova

    OpenAIRE

    Koc, Ayse Nedret; Silici, Sibel; Mutlu-Sariguzel, Fatma; Sagdic, Osman

    2007-01-01

    Vo?ni sokovi i negazirana pi?a podloni su kvarenju u prisutnosti kvasaca, plijesni i bakterija. Svrha je ovog istraivanja ispitati antifungalni u?inak etanolnog ekstrakta turskog propolisa (ETTP) u nepasteriziranom soku jabuke, naran?e, bijeloga gro?a i mandarine na 6 razli?itih sojeva kvasca izoliranih iz pokvarenih sokova. Izolirani su sojevi kvasca Candida famata, C. glabrata, C. kefyr, C. pelliculosa, C. parapsilosis i Pichia omeri. Minimalna inhibicijska koncentracija (MIC) odre?ena j...

  13. Efecto de la poda en el rendimiento de biomasa de 20 accesiones de especies arbóreas Effect of pruning on the biomass yield of 20 accessions of tree species

    Directory of Open Access Journals (Sweden)

    Odalys C Toral

    2007-09-01

    Full Text Available Se evaluó el comportamiento de 20 accesiones de arbóreas ante la poda, durante cinco años, para lo cual se utilizó un diseño de bloques al azar con ocho repeticiones. Se determinó la biomasa comestible, la biomasa leñosa y la biomasa total, así como la composición bromatológica y el número de rebrotes. En el período lluvioso manifestaron un mejor comportamiento, en cuanto al rendimiento de biomasa, L. macrophylla CIAT-17240 y L. leucocephala CIAT-17498 (3,02 y 3,15 kg de MS/árbol como promedio. El número de rebrotes osciló entre 7 y 24 y la de mejor resultado fue L. leucocephala CIAT-17498 (24 rebrotes por planta. Sin embargo, en el período poco lluvioso la producción de biomasa comestible fluctuó entre 0,10 y 1,25 kg de MS/árbol, y se destacó de nuevo L. leucocephala CIAT-17498. Un comportamiento similar al del período lluvioso se constató en los indicadores restantes. Se concluye que los mejores resultados en cuanto a la producción de biomasa comestible se encontraron en el período lluvioso; se destacó L. leucocephala CIAT-17498 en este indicador y en el número de rebrotes para ambas épocas del año. Los contenidos de materia seca, fibra bruta y proteína bruta de la biomasa comestible de las plantas, tuvieron poca variación por el efecto de la época dentro de la misma especie, tendencia que se comprobó también para los minerales. Las accesiones demostraron ser una importante alternativa para la alimentación de los rumiantes, por sus altos contenidos de proteína bruta.The performance of 20 tree accessions when pruned was evaluated during five years, for which a randomized block design with eight repetitions was used. The edible, ligneous and total biomass, as well as the bromatological composition and number of regrowths were determined. In the rainy season L. macrophylla CIAT-17240 and L. leucocephala CIAT-17498 showed a better performance, regarding biomass yield (3,02 and 3,15 kg DM/tree as average. The number of regrowths varied between 7 and 24 and the best result was observed in L. leucocephala CIAT-17498 (24 regrowths per plant. Nevertheless, in the dry season the edible biomass production fluctuated between 0,10 and 1,25 kg DM/tree, and L. leucocephala CIAT-17498 stood out again. A performance similar to that of the rainy season was observed in the other indicators. The best results regarding edible biomass production were concluded to be found in the rainy season; L. leucocephala CIAT-17498 stood out in this indicator and in the number of regrowths for both seasons. The dry matter, crude fiber and crude protein contents of the edible biomass of the plants, had little variation due to the effect of the season within the same species, a trend that was also observed for minerals. The accessions proved to be an important alternative for feeding ruminants, because of their high contents of crude protein.

  14. PRODUCCIN DE BIOMASA DE Artemia franciscana Kellogg 1906 UTILIZANDO DIFERENTES DIETAS

    Directory of Open Access Journals (Sweden)

    Rosario Cisneros

    2009-01-01

    Full Text Available Se realiz el cultivo semiintensivo de Artemia franciscana, cepa Per, 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 crustceos, con el fin de determinar la factibilidad del uso de estos para la obtencin de biomasa de adultos. El estudio se ejecut en base a un diseo experimental completamente aleatorio con 7 tratamientos y 3 rplicas cada uno, aplicndose a los datos obtenidos un Anlisis de Varianza de una va (ANOVA y la prueba de Tukey para establecer diferencias significativas entre los tratamientos. Los resultados del anlisis prximal de las dietas, mostraron que la harina de soya present la cantidad de protenas requerida por A. franciscana durante su crecimiento (34.33 %, igualmente con esta dieta se obtuvo la mejor tasa de crecimiento (0.19, biomasa ms alta (113.33 g y el mejor Factor de Conversin Alimenticia (1.4. As mismo la biomasa de A. franciscana producida con harina de soya, present un nivel de protenas adecuado para la maduracin de reproductores de crustceos (53.38 %.

  15. PRODUCCIÓN DE BIOMASA DE Artemia franciscana Kellogg 1906 UTILIZANDO DIFERENTES DIETAS

    Directory of Open Access Journals (Sweden)

    Rosario Cisneros

    2009-01-01

    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 del 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 %.

  16. Security in VoIP

    Directory of Open Access Journals (Sweden)

    Floriana GEREA

    2012-04-01

    Full Text Available 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 other security threats aimed at the technology also will grow. The current paper's purpose is presenting several security solutions and applying them to integrated systems at an economical and social level.

  17. Oxygen potential in the system LaVO3-LaVO4

    International Nuclear Information System (INIS)

    A solid electrolyte EMF technique was used in the present investigation to characterize the oxygen chemical potential in the system LaVO3-LaVO4 employing the following cells: Pt, LaVO4, LaVO3/YSZ/O2(Po2=2.4x10-2 atm) Pt I; Pt, LaVO4, LaVO3La2O3/YSZ/O2(Po2=2.4x10-2 atm) Pt II; (YSZ: 15 weight pct yttria stabilized zirconia tube). There was no significant systematic difference in the EMF of cells I and II showing that the solid solubility (if any) of La2O3 (s) in the ternary oxide phases has negligible effect on the oxygen potential in the system LaVO4-LaVO3. After correcting for the standard state, the EMF of cells I and II could be represented by a single least square expression E+-13/mV=1576-0.652T (11334, LaVO3 or LaVO4, LaVO3, La2O3) /YSZ/ O2(Po2=1 atm.) Pt III. From equation (1) the following expression for free energy change Δsub(R)G0 +-2.5/kJ=-304.1+0.1258 T ...(2) for the reaction, LaVO3(s)+1/2O2(g) reversible LaVO4(s) was derived. The internal consistency of the EMF data was confirmed using Ni-NiO reference electrode. (author)

  18. VO2max during successive maximal efforts

    OpenAIRE

    Foster, Carl; Kuffel, Erin; Bradley, Nicole; Battista, Rebecca A.; Wright, Glenn; John P. Porcari; Luc?a Mulas, Alejandro; De Koning, Jos J.

    2007-01-01

    The concept of VO(2)max has been a defining paradigm in exercise physiology for >75 years. Within the last decade, this concept has been both challenged and defended. The purpose of this study was to test the concept of VO(2)max by comparing VO(2) during a second exercise bout following a preliminary maximal effort exercise bout. The study had two parts. In Study #1, physically active non-athletes performed incremental cycle exercise. After 1-min recovery, a second bout was performed at a hig...

  19. VoIP in Jabber Client

    OpenAIRE

    Kulička, Vojtěch

    2011-01-01

    Práce se zabývá možnostmi implementace VoIP do existujícího XMPP programu se sdílenou tabulí. Analyzuje možnosti využití současných technologií pro podporu VoIP.  Cílem je nahrazení stávajících komunikačních knihoven klienta za telepathy. Dále také přidání VoIP.

  20. Digital Forensics in VoIP networks

    OpenAIRE

    François, Jérôme; State, Radu; Engel, Thomas; Festor, Olivier

    2010-01-01

    With VoIP being deployed on large scale, forensic analysis of captured VoIP traffic is of major practical interest. In this paper, we present a new fingerprinting approach that identifies the types of devices (name, version, brand, series) in captured VoIP traffic. We focus only on the signaling plane and discard voice related data. Although we consider only one signaling protocol for the illustration, our tool relies on structural information trees and can easily be adapted to any protocol o...

  1. Fuzzing dans la sphre VoIP

    OpenAIRE

    Abdelnur, Humberto; Festor, Olivier; State, Radu

    2008-01-01

    La voix sur IP (VoIP) s'impose aujourd'hui comme l'une des technologies clefs de l'Internet actuel et futur. Dans cet article, nous partageons l'exprience pratique acquise ces deux dernires annes par notre quipe de recherche sur l'automatisation des processus de dcouverte de vulnrabilits dans le monde VoIP. Nous dressons un portrait relativement sombre de la scurit actuelle de la sphre VoIP en prsentant les vulnrabilits les plus dangereuses capables d'aboutir la compromission d...

  2. 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.

  3. 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.

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

    OpenAIRE

    TALAL AL-KHAROBI; Mohmmed Abduallah Al-Mehdhar

    2012-01-01

    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 ...

  5. VoIP technology comes of age.

    Science.gov (United States)

    2008-04-01

    Cabling specialist Connectix examines the growing potential for healthcare sector use of VoIP technology and highlights the importance of correct cabling infrastructure as a carrier of both voice and high-speed data traffic. PMID:18494421

  6. A Comprehensive Secure VoIP Solution

    Directory of Open Access Journals (Sweden)

    Ashraf D. Elbayoumy

    2007-09-01

    Full Text Available VoIP represents the future of digital voice communications and many carriers are preparing for the VoIP revolution. However, a number of outstanding issues need to be settled. The most important are security, compression, packet size optimization, quality of service and performance in heterogeneous networks. We have addressed all of these issues [2, 3, 4, 5] and here we summarize our key findings in each of these areas.

  7. 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.  

  8. 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.

  9. 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.

  10. INCORPORACIN DE BIOMASA EN UN SUELO VERTISOL Y SU RELACIN CON LA DENSIDAD DE COMPACTACIN

    Directory of Open Access Journals (Sweden)

    Euriel Milln

    2013-01-01

    Full Text Available Un suelo compactado evidencia un deterioro en las propiedades fsicas y afecta el crecimiento de las plantas. El objetivo de este estudio fue evaluar los efectos que produce la incorporacin de biomasa en un ensayo de compactacin, a un suelo de explotacin ganadera sobre las curvas de compactacin del mismo. Se utiliz un suelo Vertisol de Sincelejo (Sucre. Se analizaron las propiedades fsicas del suelo, como textura, densidad real y aparente; densidades mximas de compactacin y contenidos de humedad en los que se alcanzaba dicha compactacin. Se determin mediante software estadstico la relacin que existe entre la incorporacin de materia orgnica y las variaciones en la densidad mxima y la humedad del suelo. Para determinar la densidad mxima del suelo y humedad crtica se utiliz diseo de bloques completos al azar, con tres repeticiones. Los tratamientos estudiados corresponden a un factorial 2 X 4, siendo dos los tipos de materia orgnica (hmeda y seca, y cuatro las cantidades de materia orgnica. Se encontr que la densidad mxima en condiciones normales (sin incorporacin de materia orgnica es de 1,421 g cm-3 y 26,573% de humedad; se alcanzaron valores de 1,406 g cm-3 y 28,074%, y 1,379 g cm-3 y 26,833% para incorporaciones de 20 Mg ha-1 de biomasa hmeda y seca respectivamente. La densidad mxima con respecto a la cantidad y tipo de materia orgnica incorporada seala un efecto estadsticamente significativo. La incorporacin de biomasa al suelo Vertisol ayuda a disminuir las densidades mximas de compactacin, y aumenta el contenido de humedad.

  11. Factores del manejo para estabilizar la produccin de biomasa con leguminosas en el trpico

    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 produccin de biomasa en sistemas ganaderos en el trpico. Es obvio que los sistemas mejorados y bien manejados de pasturas de gramneas y leguminosas, en cualquiera de sus alternativas, son opciones para lograr la sostenibilidad. Una concepcin ms amplia y profunda es la relativa a los estudios de pasturas mixtas; stos, deben tener un enfoque ms biolgico por lo que, adems 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. Aqu no podemos olvidar el efecto del animal. Los problemas asociados con la persistencia se reconocen cada vez ms como una preocupacin 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, as como en los que ste no puede intervenir. Es por ello que las producciones animales y de otro tipo, derivados de estos sistemas, varan positivamente en el tiempo, en la medida en que se va consolidando la relacin suelo /planta /animal. De esta correspondencia no puede quedar excluido el papel interactuante y modificador del hombre con los elementos antes sealados. La produccin de biomasa es una actividad multidisciplinaria; de ah que el xito de su funcionamiento est condicionado al conocimiento de las interacciones entre sus componentes, as como entre stos y el medio ambiente, lo cual permitir la generacin de estrategias de manejo acordes con la ecologa que conduzcan a mejorar la productividad y la sostenibilidad del agroecosistema. Por tanto, la produccin de biomasa constituye un elemento determinante en el xito y la eficiencia de los sistemas con leguminosas.

  12. LA BIOMASA MICROBIANA EN SUELOS DE MONTAÑA CON DIFERENTES USOS: UN ESTUDIO DE LABORATORIO

    Directory of Open Access Journals (Sweden)

    A. Cruz Ruiz

    2012-01-01

    Full Text Available El uso agrícola de los suelos del Parque Nacional Nevado de Toluca (PNTT, conlleva prácticas como la utilización creciente de agroquímicos. Para investigar el efecto de la aplicación de fertilizantes nitrogenados y biocidas de uso generalizado en la zona de estudio sobre la biomasa microbiana y la mineralización del carbono (C, se realizó una incubación de suelos del PNNT con diferentes usos: bosque (bajo la copa de oyamel (Abies religiosa, destinados al pastoreo (pradera y cultivado con maíz. Con los siguientes tratamientos: sulfato deamonio (585.36 kg ha-1, urea (250 kg ha-1, 2, 4-D (1 L ha-1, captan (2 kg ha-1 y suelos sin aplicación. La mineralización del C, el nitrógeno de la biomasa microbiana (NBM y el carbono de la biomasa microbiana (CBM se midieron a los 56 días de incubación. Los resultados mostraron que el cambio de uso de suelo de bosque a cultivo disminuye la biomasa microbiana, la proporción de CBM y NBM en los suelos de cultivo fue menor en más del 55% en comparación con los suelos de bosque. Los tratamientos 2, 4-D y captan dieron lugar al decremento significativo del CBM en los suelos de bosque, hasta en un 40 %, con respecto al suelo sin aplicación. La aplicación de captan favoreció el incremento del CBM en los suelos de pradera y cultivo. El NBM aumentó en los tres suelos con diferente uso al aplicar urea. La adición de sulfato de amonio, urea, 2, 4-D amina o captan causa efectos diferenciados en los suelos de bosque, pradera y cultivo indicando que el impacto de los biocidas y fertilizantes está relacionado con la degradación de los mismos.

  13. Transformacin de biomasa en biocombustibles de segunda generacin / From biomass to second generation biofuels

    Scientific Electronic Library Online (English)

    Laura, Faba; Eva, Daz; Salvador, Ordez.

    2014-11-01

    Full Text Available El agotamiento de las materias primas no renovables, as como la creciente conciencia ambiental ha motivado la valorizacin de la biomasa para la produccin de energa. Aunque los primeros esfuerzos se centraron en el desarrollo de los biocombustibles de primera generacin -segn la materia prima co [...] n que se producen-, la tendencia actual es hacia la investigacin en los biocombustibles de segunda generacin, que permiten la transformacin de la biomasa lignocelulsica (obtenida a partir de residuos forestales o de cultivos, maderas de bajo precio o serrn) en energa. La transformacin de la madera en biocombustibles puede llevarse a cabo por vas biolgicas o qumicas. Entre las rutas qumicas, hay tres posibilidades principales: gasificacin, pirlisis o hidrlisis. Este trabajo tiene como objetivo hacer una revisin de las posibilidades para obtener biocombustibles de segunda generacin mediante procesos qumicos hidrolticos, que implica varios pasos: pretratamiento de la biomasa (que puede ser fsico o qumico), hidrlisis de la biomasa, deshidratacin de los azcares, condensacin aldlica e hidrogenacin/deshidratacin completa para obtener los alcanos lineales (biodiesel). Abstract in english The depletion of the non-renewable raw materials as petroleum, coal or natural gas as well as the increasing environmental conscience has motivated the valorization of biomass for energy production. Although the first efforts were focused on the development of the first generation biofuels -accordin [...] g to the raw material-, nowadays the research is focused on the second generation biofuels, which allows the transformation of lignocellulosic biomass (from forest or crops wastes, low-priced woods or sawdust) into energy. The transformation of wood into biofuels can be carried out by biological or chemical means. Among the chemical routes, there are three main possibilities: gasification, pyrolisis or hydrolysis. This paper aims to review the technological advances to obtain biofuels by the third route, since it allows using the most abundant forms of biomass, cellulose and hemicelluloses. This chemical process involves several steps: pretreatment of the biomass (by physical or chemical route), hydrolysis of the biomass, dehydration of sugars, aldolization and hydrogenation/dehydration until n-alcanes (biofuels) are achieved.

  14. Importancia energética y ambiental de la biomasa en colombia

    OpenAIRE

    Hernández Luis Alfredo

    2011-01-01

    Entiéndase por energía de la biomasa aquélla que se origina al procesar parcial o totalmente cualquier sustancia o materia originada a través del proceso de fotosíntesis de los vegetales. Luego comprende especies y microespecies que cumplen para el hombre y el ecosistema una función especial ...

  15. 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.

  16. Efecto de nutrientes sobre la producción de biomasa del hongo medicinal ganoderma lucidum

    OpenAIRE

    Ana María Torres López; Juan Carlos Quintero Díaz; Lucía Atehortua Garcés

    2011-01-01

     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 r...

  17. 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 β-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

  18. VO2max during successive maximal efforts.

    Science.gov (United States)

    Foster, Carl; Kuffel, Erin; Bradley, Nicole; Battista, Rebecca A; Wright, Glenn; Porcari, John P; Lucia, Alejandro; deKoning, Jos J

    2007-12-01

    The concept of VO(2)max has been a defining paradigm in exercise physiology for >75 years. Within the last decade, this concept has been both challenged and defended. The purpose of this study was to test the concept of VO(2)max by comparing VO(2) during a second exercise bout following a preliminary maximal effort exercise bout. The study had two parts. In Study #1, physically active non-athletes performed incremental cycle exercise. After 1-min recovery, a second bout was performed at a higher power output. In Study #2, competitive runners performed incremental treadmill exercise and, after 3-min recovery, a second bout at a higher speed. In Study #1 the highest VO(2) (bout 1 vs. bout 2) was not significantly different (3.95 +/- 0.75 vs. 4.06 +/- 0.75 l min(-1)). Maximal heart rate was not different (179 +/- 14 vs. 180 +/- 13 bpm) although maximal V(E) was higher in the second bout (141 +/- 36 vs. 151 +/- 34 l min(-1)). In Study #2 the highest VO(2) (bout 1 vs. bout 2) was not significantly different (4.09 +/- 0.97 vs. 4.03 +/- 1.16 l min(-1)), nor was maximal heart rate (184 + 6 vs. 181 +/- 10 bpm) or maximal V(E) (126 +/- 29 vs. 126 +/- 34 l min(-1)). The results support the concept that the highest VO(2) during a maximal incremental exercise bout is unlikely to change during a subsequent exercise bout, despite higher muscular power output. As such, the results support the "classical" view of VO(2)max. PMID:17891414

  19. Lattice relaxation and ferromagnetic character of (LaVO3)m/SrVO3superlattices

    Science.gov (United States)

    Schuster, Cosima; Lders, Ulrike; Frsard, Raymond; Schwingenschlgl, Udo

    2013-08-01

    The experimental observation that vanadate superlattices (LaVO3)m/SrVO3 show ferromagnetism up to room temperature (Lders U. et al., Phys. Rev. B, 80 (2009) 241102(R)) is investigated by means of density functional theory, and the band structure for m = 5 and 6 is calculated. A buckling of the interface VO2 layers is found in both cases, but subtle differences in bond length lead to very different properties for even and odd values of m: in the even case, the two interface VO2 layers effectively decouple from the adjacent LaO layers due to a strong bond length enhancement. This results into a local inversion of the orbital occupancy and to the confinement of the charge carriers. In the odd case, the amplitude of the bond length variation is smaller, so that the charge carriers spill into the deeper-lying VO2 layers, and spin-polarised interfaces are obtained.

  20. Security in VoIP-Current Situation and Necessary Development

    OpenAIRE

    Gao, Li Li

    2006-01-01

    Nowadays, VoIP is getting more and more popular. It helps company to reduce cost, extends service to remote area, produce more service opportunities, etc. Besides these advantages, VoIP also put forward security problems. In this paper, we introduce the popular protocols in VoIP and their security mechanisms, by introducing threats to VoIP, we point out the vulnerabilities with the security mechanisms of each VoIP protocol, and give recommendation for each VoIP protocol. In the conclusion par...

  1. Control de una planta prototipo de gasificacin de biomasa mediante redes neuronales

    Directory of Open Access Journals (Sweden)

    Carlos A. Forero Nez

    2013-01-01

    Full Text Available Los sistemas de gasificacin de Biomasa son una alternativa para emplear residuos agroindustriales y generar un combustible ga- seoso; sin embargo, estos procesos no lineales se ven afectados por las caractersticas tpicas del material y por la variacin en las temperaturas al interior del equipo, por lo tanto se requieren sistemas de control para alcanzar estados estables en el tiempo. Este trabajo analiza el desempeo de un control mediante redes neuronales aplicado a un gasificador de lecho fijo corriente descenden- te 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 600C a 800C en la zona de inyeccin, superando as el problema derivado de la baja transferencia de energa por conduccin a travs del sistema. Cuando se emplea el control en la gasificacin de cuesco, la temperatura promedio se mantuvo constante en 790C, el CO presente en el gas estuvo alrededor de 10% mientras que el CO2 disminuy a 4%. La aplicacin 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 sntesis con menor contenido de CO2. Esto para un pas con gran diversidad de recursos agroindustriales abre la posibilidad de usar estos subproductos en la generacin de energa a partir de fuentes renovables.

  2. CONCENTRACIN DE CARBONO EN LA BIOMASA AREA DEL MATORRAL ESPINOSO TAMAULIPECO

    Directory of Open Access Journals (Sweden)

    Jos I. Yerena-Yamallel

    2011-01-01

    Full Text Available Se determin la concentracin 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 concentracin de carbono expresado como porcentaje de la biomasa, se hizo con el equipo Solids TOC Analyzer, que determina la concentracin de carbono en muestras slidas a travs de combustin completa. Mediante un ANAVA no se encontraron diferencias en la concentracin promedio de carbono de las especies (P>0.05; esta concentracin vari de 44.25 a 47.08 % con una media general de 45.41.32 %; Cordia boissieri (44.251.52 % y Acacia farnesiana (44.521.37 % son las especies que resultaron con los valores de concentracin de carbono menores, y Forestiera angustifolia (47.081.27 % con el ms alto. El componente corteza de Cordia boissieri obtuvo el menor porcentaje de concentracin de carbono (39.620.70 %, y las hojas de Acacia schaffneri el mayor (50.141.21 %; la interaccin de ambos factores result significativa (P<0.0001.

  3. BIOMASA, PROLINA Y PARMETROS NITROGENADOS EN PLNTULAS DE NOGAL BAJO ESTRS HDRICO Y FERTILIZACIN NITROGENADA

    Directory of Open Access Journals (Sweden)

    Guadalupe Alejandra de la O-Quezada

    2011-01-01

    Full Text Available Se realiz un estudio cuyo objetivo fue medir la respuesta de los procesos fisiolgicos bajo las condiciones de estrs hdrico y concentracin de nitrgeno (N en plantas de nogal pecanero [Carya illinoinensis (Wangenh C. Koch]. El experimento consisti en la siembra, crecimiento y desarrollo de plantas a partir de semillas de nogal pecanero Western Schley; las cuales fueron sometidas a diferentes manejos: aportacin de riego y N, aportacin de riego sin N, estrs hdrico y adicin de N y finalmente bajo estrs hdrico y ausencia de N. Fueron evaluadas las siguientes variables: altura de planta, dimetro de tronco, concentracin de clorofila (unidades SPAD y metanol, nmero de hojas e ndice de rea foliar, prolina y biomasa. Los resultados demostraron que, las plntulas con aportacin de N y estrs hdrico redujeron la concentracin de Nt y N-NO3 - en 21.73 y 61.84 % respectivamente, rea foliar y dimetro de tronco en un 53.4 y 36.5 %, respectivamente, incrementndose el contenido de prolina en 39.41 %. Con riego y en ausencia de N se disminuy el contenido de clorofila en 20 % y la biomasa de tallo en 58.34 %, finalmente el contenido relativo de agua (CRA de tallo y raz decreci en 61.54 y 60.17 % respectivamente.

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

    International Nuclear Information System (INIS)

    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.

  5. RELACIN ENTRE LA BIOMASA Y ALGUNAS CARACTERSTICAS MORFOLGICAS DE LAS BROMELIAS FITOTELMATAS DE UN BOSQUE ALTO ANDINO COLOMBIANO

    Directory of Open Access Journals (Sweden)

    Isaza Carolina

    2009-06-01

    Full Text Available Se evaluaron algunas caractersticas morfolgicas para seis especies de bromelias fitotelmata (Guzmania gloriosa, Racinaea tetrantha, Tillandsia biflora, T. complanata, T. fendleri y T. turneri con el fin de establecer cuales caractersticas podran utilizarse como estimadores indirectos de la biomasa total de la planta. El estudio se realiz en un bosque alto andino de la Sabana de Bogot, Colombia, ubicado a 2900 m de altitud. Para cada especie se recolectaron entre 32 y 64 individuos en diferentes estadios de crecimiento, a cada uno de los cuales se le registr: 1 el nmero de hojas por roseta; 2 el permetro de la base de la roseta; 3 la cobertura de la planta; 4 el largo de la lmina foliar; 5 la altura de la roseta; y 6 la biomasa total. Los resultados de la prueba Wilcoxon muestran que la cobertura fue la variable que ms se relacion con la biomasa. Una prueba de ajuste de curva mostr que la lnea recta es la que ms explica la relacin entre la cobertura y la biomasa, permitiendo hacer estimaciones a partir de la ecuacin sin ser necesario un muestreo destructivo.

  6. Proceso de gasificacin de biomasa: una revisin de estudios terico- experimentales / Biomass gasification process: theoretical and experimental studies a review

    Scientific Electronic Library Online (English)

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

    2010-03-01

    Full Text Available La situacin energtica y medioambiental mundial hace que la generacin de energa mediante sistemas basados en energas renovables tome cada vez una mayor relevancia. Estos sistemas tienen una doble ventaja ya que posibilitan la diversificacin energtica y reducen la dependencia del petrleo a la [...] vez que se disminuyen las emisiones globales de CO2. La biomasa es uno de los recursos energticos con mayor potencial tanto en pases desarrollados como emergentes pero sigue sin sufrir el desarrollo esperado. La gasificacin de biomasa es uno de los sistemas con gran potencial ya que permite la generacin tanto de energa trmica como elctrica, mediante tecnologas de bajo costo como los gasificadores de lecho fijo (potencias medias- bajas), o reactores de lecho fluidizado con tecnologa ms exigente y con mayor capacidad de generacin. La transformacin de la biomasa en un combustible gaseoso, aprovechable en motores de combustin interna alternativos o en turbinas de gas como combustible, exige que la biomasa atraviese varios procesos termoqumicos, compuestos por reacciones endotrmicas (secado, devolatilizacin y reduccin) y exotrmicas (oxidacin de voltiles y carbn). La seleccin de un gasificador requiere conocer las propiedades de la biomasa, mientras que el diseo del mismo exige conocer el fenmeno termoqumico por completo. El objetivo de este trabajo es presentar una revisin actualizada de los diferentes planteamientos tanto tericos como experimentales desarrollados para estudiar el proceso de gasificacin de biomasa, tanto en lecho fijo como en lecho fluidizado, con miras a disear 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.

  7. Holistic VoIP Intrusion Detection and Prevention System

    OpenAIRE

    Nassar, Mohamed; Niccolini, Saverio; State, Radu; Ewald, Thilo

    2007-01-01

    VoIP security is crucial for current and future networks and services. The rapid shift from a closed and confined telephony towards an all IP network supporting end to end VoIP services provides major challenges to the security plane. Faced with multiple attack vectors, new and comprehensive defensive security solutions for VoIP must emerge from the research community. This paper describes a multilayer intrusion detection and prevention system architecture for VoIP infrastructures. The key co...

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

    Directory of Open Access Journals (Sweden)

    María J Gualtieri A

    2007-12-01

    Full Text Available 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 propósito 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 animalThe 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

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

    Directory of Open Access Journals (Sweden)

    V. Martínez

    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.

  10. Euro-VO-Coordination of virtual observatory activities in Europe

    Science.gov (United States)

    Genova, Françoise; Allen, Mark G.; Arviset, Christophe; Lawrence, Andy; Pasian, Fabio; Solano, Enrique; Wambsganss, Joachim

    2015-06-01

    The European Virtual Observatory Euro-VO has been coordinating European VO activities through a series of projects co-funded by the European Commission over the last 15 years. The bulk of VO work in Europe is ensured by the national VO initiatives and those of intergovernmental agencies. VO activities at the European level coordinate the work in support of the three "pillars" of the Virtual Observatory: support to the scientific community, take-up by the data providers, and technological activities. Several Euro-VO projects have also provided direct support to selected developments and prototyping. This paper explains the methodology used by Euro-VO over the years. It summarises the activities which were performed and their evolutions at different stages of the development of the VO, explains the Euro-VO role with respect to the international and national levels of VO activities, details the lessons learnt for best practices for the coordination of the VO building blocks, and the liaison with other European initiatives, documenting the added-value of European coordination. Finally, the current status and next steps of Euro-VO are briefly addressed.

  11. COMPORTAMIENTO DE LA ACUMULACIN Y DISTRIBUCIN DE BIOMASA EN GENOTIPOS DE PAPA ESTABLECIDOS EN CONDICIONES DE SECANO

    Directory of Open Access Journals (Sweden)

    R. Mora-Aguilar

    2005-01-01

    Full Text Available El estudio se realiz durante el periodo de secano de 1996, en Metepec, Mxico, para determinar el comportamiento de la acumulacin y distribucin de biomasa en los diferentes rganos y en la planta completa de cinco genotipos de papa; stos fueron establecidos en surcos de 90 cm de anchura y 30 cm de distancia entre plantas de un slo tallo. Despus de la emergencia, a intervalos de 71 das, fueron cosechadas cinco plantas en competicin completa y disecadas la parte area (hojas, tallo principal y tallo de ramas y subterrnea (races, estolones, tubrculos y seccin enterrada del tallo principal. Posteriormente fueron puestas a secar en una estufa con aire forzado a 75 C por 72 h hasta alcanzar su peso seco constante. El comportamiento de la acumulacin y distribucin de biomasa hacia los diferentes rganos de la planta estuvo asociada, en la mayora de los casos, con el hbito de crecimiento de los genotipos: determinado en 'Alpha', 'Nortea' y 'C-771A11', o indeterminado en 'Puebla' y 'C-676014'. Las curvas de acumulacin fueron similares entre genotipos y su tendencia general se ajust a modelos de tipo logstico o polinomial. A partir de los 45 a 50 das despus la emergencia, la acumulacin de biomasa en la parte subterrnea y la planta completa fue casi paralela. La duracin de la etapa de tuberizacin afect la acumulacin de biomasa en los tubrculos de manera que los genotipos de ciclo intermedio, como 'Nortea' y 'C-676014', fueron ms eficientes (272 y 294 gplanta-1 que los precoces o tardos. Entre los rganos areos, las hojas acumularon ms biomasa (40-53 y 79-81 gplanta-1, independientemente del hbito de crecimiento de los genotipos.

  12. A low cost preparation of VO2 thin films with improved thermochromic properties from a solution-based process

    International Nuclear Information System (INIS)

    This paper describes a solution-based route to synthesize vanadium dioxide (VO2) thermochromic thin films on glass substrate by spin-coating technology followed by nitrogen-annealing with vanadium pentoxide (V2O5) and oxalic acid (H2C2O4) as source material, which is fairly economical and practical. Surface morphologies indicate that the films obtained by this method are homogeneous and particulate, irregular prisms emerge as the annealing temperatures increase. X-ray diffractions show that films annealed at relatively low temperature are pure monoclinic phase with a preferred orientation of (011). NaV4O7 and NaV6O15 form along with raising the heating temperatures. VO2 films obtained exhibit excellent visible transparency and switching property at near-infrared wavelengths across the metalsemiconductor transition. Transmittance change at ? = 2000 nm of VO2 thin film annealed at 450 C attains as high as 41.5% and its solar modulation efficiency reaches up to 8.8%. The W-doped VO2 film at a doping level of 1 at.% exhibits a thermochromic switch at 37 C with a narrow hysteresis, which will greatly favor the practical application of VO2-based smart windows. - Highlights: ? Vanadium dioxide thermochromic film was prepared via a solution-based deposition. ? Tungsten doping reduced the phase transition temperature to 37 C. ? Tungsten doping narrowed the transmittance hysteresis loop. ? Our results will propel the application to vanadium dioxide-based smart windows

  13. Electrochemical catalytic activity of tungsten trioxide- modified graphite felt toward VO2+/VO2+ redox reaction

    International Nuclear Information System (INIS)

    A novel graphite felt electrode modified with tungsten trioxide (WO3) was developed to improve the electrochemical performance of graphite felt toward the VO2+/VO2+ redox pair. WO3 was prepared using a hydrothermal method, and the morphology of WO3 structures was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical property of WO3-modified graphite felt toward VO2+/VO2+ was carefully characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The hydrogen-vanadium redox flow battery (H-VRFB) test indicates that single cells using 1.1 mg cm−2 WO3-modified graphite felt exhibited excellent performance at 70 mA cm−2, and the corresponding coulombic, voltage, and energy efficiencies were 99.1%, 88.66% and 87.86%, respectively

  14. VoIP in a Campus Environment

    Science.gov (United States)

    Young, Dan

    2005-01-01

    Internet Protocol (IP) Telephony, or voice-over IP (VoIP), has proved to be a wise decision for many organizations. This technology crosses the boundaries of public and private networks, enterprise and residential markets, voice and data technologies, as well as local and long-distance services. The convergence of voice and data into a single,…

  15. How To: Be VoIP-Savvy

    Science.gov (United States)

    Branzburg, Jeffrey

    2005-01-01

    Cablevision, Comcast, Verizon, and many other high-speed broadband Internet providers are now also offering telephone services through "Voice over Internet Protocol" (VoIP). This technology sends ordinary telephone calls over the Internet rather than over telephone lines. While impractical without the use of a broadband Internet connection, with…

  16. Is VoIP Worth It?

    Science.gov (United States)

    Schaffhauser, Dian

    2008-01-01

    School districts have by and large had great results implementing VoIP, which has become the conduit for delivering expanded functionality, achieving greater internal control, and gaining freedom from onerous monthly phone bills. But demonstrating a financial return on what is a substantial investment can be an elusive effort. The goal of…

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

    OpenAIRE

    CLAUDIO MUÑOZ RIVEROS; JORGE CANCINO C; MIGUEL ESPINOSA B

    2005-01-01

    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 valores 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 cort...

  18. Polycrystalline VO2 thin films via femtosecond laser processing of amorphous VO x

    Science.gov (United States)

    Charipar, N. A.; Kim, H.; Breckenfeld, E.; Charipar, K. M.; Mathews, S. A.; Piqué, A.

    2016-05-01

    Femtosecond laser processing of pulsed laser-deposited amorphous vanadium oxide thin films was investigated. Polycrystalline VO2 thin films were achieved by femtosecond laser processing in air at room temperature. The electrical transport properties, crystal structure, surface morphology, and optical properties were characterized. The laser-processed films exhibited a metal-insulator phase transition characteristic of VO2, thus presenting a pathway for the growth of crystalline vanadium dioxide films on low-temperature substrates.

  19. 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

  20. Importancia energética y ambiental de la Biomasa en Colombia

    Directory of Open Access Journals (Sweden)

    Hernández Luis Alfredo

    1994-12-01

    Full Text Available

    Entiéndase por energía de la biomasa aquélla que se origina al procesar parcial o totalmente cualquier sustancia o materia originada a través del proceso de fotosíntesis de los vegetales. Luego comprende especies y microespecies que cumplen para el hombre y el ecosistema una función especial ligada a factores climáticos, geomorfológicos y socioeconómicos. Antes de la aparición de los combustibles fósiles (otra forma concentrada de biomasa y de la electricidad, la biomasa constituía la principal oferta energética para el desarrollo y sobrevivencia del hombre. Si se tiene en cuenta que en el proceso de alimentación humana, el hombre y los animales utilizan menos del10% de la biomasa producida, queda un sobrante en estado sólido o en suspensión y que, por sus grandes volúmenes, genera problemas de contaminación en el campo y la ciudad, por ejemplo, basuras, residuos de plazas de mercado, pulpa de café, residuos de matadero, de procesamiento de vegetales, lácteos, y licoreras, residuos domésticos y residuos animales entre otros. Para el procesamiento o aprovechamiento de estos residuos existen tecnologías que buscan incorporarlos, en términos de materia y/o energía, a los procesos energéticos y agrícolas, captando de ellos, principalmente los valiosos elementos que los originaron. Dentro de estas tecnologías vale resaltar aquéllas basadas en los procesos microbiológicos, como las fermentaciones aeróbica y anaeróbica con un impacto ambiental nulo o positivo, reduciendo a nivel urbano los efectos de la contaminación y aportando fertilizantes y energía en el sector rural para la producción agrícola y bienestar social. Un efecto de su implantación sería la reducción de la contaminación de las aguas por material orgánico y sedimentos y la disminución en el consumo de, por lo menos unos diez millones de toneladas de leña al año que son utilizados por nuestros campesinos en sus actividades domésticas y de producción.

  1. Visible light driven photocatalysis and antibacterial activity of AgVO3 and Ag/AgVO3 nanowires

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Ag/AgVO3 and pure AgVO3 nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO3 within 45 min. • Antibacterial activity of Ag/AgVO3 demonstrated. - Abstract: Ag/AgVO3 nanowires and AgVO3 nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO3 nanowires. The photocatalytic studies revealed that the Ag/AgVO3 nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO3 nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO3 nanorods prove that in case of the Ag dispersed Ag/AgVO3 nanowires, the enhanced antibacterial action is also due to contribution from the AgVO3 support

  2. BIOMASA Y RENDIMIENTO DE FRIJOL CON POTENCIAL EJOTERO EN UNICULTIVO Y ASOCIADO CON GIRASOL

    Directory of Open Access Journals (Sweden)

    J. Garduño-González

    2009-01-01

    Full Text Available El objetivo del presente estudio fue estimar la producción de biomasa, rendimiento y algunos de sus componentes de dos cultivares de frijol (Phaseolus vulgaris L. con potencial ejotero ('Acerado' y 'Criollo', en unicultivo y asociado con dos cultivares de girasol (Helianthus annuus L. ('Sunbright' y 'Victoria'. El estudio se realizó durante el ciclo primavera verano 2006 bajo condiciones de temporal en Tenancingo, Méx. Las variables evaluadas fueron: índice de área foliar (IAF, tasa de asimilación neta (TAN, biomasa total (BT, diámetro de vaina (DV, longitud de vaina (LV, número de vainas·m-2 (NV y rendimiento de vaina·m-2 (RV; las cuales fueron analizadas en arreglo factorial, bajo un diseño de bloques completos al azar con cuatro repeticiones. Para estimar el grado de asociación, entre las variables estudiadas y el rendimiento de vainas, se realizó un análisis de correlación lineal simple. En el factor cultivares se detectaron diferencias estadísticas significativas para la TAN y DV; para el factor sistemas de siembra hubo diferencias significativas para BT, DV, NV y RV. La interacción cultivares * sistema de siembra fue significativa en todas las variables, excepto en la TAN. En ese sentido, las asociaciones 'Criollo' + 'Sunbright', 'Acerado' + 'Victoria' y 'Acerado' en unicultivo, presentaron el mayor RV. Las variables IAF, BT y NV se correlacionaron positiva y significativamente con el rendimiento de vaina. Los resultados indican que 'Criollo' y 'Acerado', asociados con 'Sunbright' y 'Victoria', respectivamente, responden positivamente a la asociación, constituyendo una buena opción para los productores de la región de Tenancingo, México.

  3. Using VoIP to compete.

    Science.gov (United States)

    Werbach, Kevin

    2005-09-01

    Internet telephony, or VoIP, is rapidly replacing the conventional kind. This year, for the first time, U.S. companies bought more new Internet-phone connections than standard lines. The major driver behind this change is cost. But VoIP isn't just a new technology for making old-fashioned calls cheaper, says consultant Kevin Werbach. It is fundamentally changing how companies use voice communications. What makes VoIP so powerful is that it turns voice into digital data packets that can be stored, copied, combined with other data, and distributed to virtually any device that connects to the Internet. And it makes it simple to provide all the functionality of a corporate phone-call features, directories, security-to anyone anywhere there's broadband access. That fosters new kinds of businesses such as virtual call centers, where widely dispersed agents work at all hours from their homes. The most successful early adopters, says Werbach, will focus more on achieving business objectives than on saving money. They will also consider how to push VoIP capabilities out to the extended organization, making use of everyone as a resource. Deployment may be incremental, but companies should be thinking about where VoIP could take them. Executives should ask what they could do if, on demand, they could bring all their employees, customers, suppliers, and partners together in a virtual room, with shared access to every modern communications and computing channel. They should take a fresh look at their business processes to find points at which richer and more customizable communications could eliminate bottlenecks and enhance quality. The important dividing line won't be between those who deploy Vol P and those who don't, or even between early adopters and laggards. It will be between those who see Vol P as just a new way to do the same old things and those who use itto rethink their entire businesses. PMID:16171218

  4. Service Improvements for a VoIP Provider

    OpenAIRE

    Li, Zhang

    2009-01-01

    This thesis project is on helping a Voice over Internet Protocol (VoIP) service provider by improving server side of Opticall AB's Dial over Data solution. Nowadays, VoIP is becoming more and more popular. People use VoIP to call their family and friends every day. It is cheap, especially when users are abroad, because that they do need to pay any roaming fee. Many companies also like their employees to use VoIP, not only because the cost of calling is cheap, but using VoIP means that the com...

  5. Euro-VO - Coordination of Virtual Observatory activities in Europe

    CERN Document Server

    Genova, Francoise; Arviset, Christophe; Lawrence, Andy; Pasian, Fabio; Solano, Enrique; Wambsganss, Joachim

    2015-01-01

    The European Virtual Observatory Euro-VO has been coordinating European VO activities through a series of projects co-funded by the European Commission over the last 15 years. The bulk of VO work in Europe is ensured by the national VO initiatives and those of intergovernmental agencies. VO activities at the European level coordinate the work in support of the three "pillars" of the Virtual Observatory: support to the scientific community, take-up by the data providers, and technological activities. Several Euro-VO projects have also provided direct support to selected developments and prototyping. This paper explains the methodology used by Euro-VO over the years. It summarizes the activities which were performed and their evolutions at different stages of the development of the VO, explains the Euro-VO role with respect to the international and national levels of VO activities, details the lessons learnt for best practices for the coordination of the VO building blocks, and the liaison with other European i...

  6. Epitaxial stabilization and phase instability of VO2 polymorphs.

    Science.gov (United States)

    Lee, Shinbuhm; Ivanov, Ilia N; Keum, Jong K; Lee, Ho Nyung

    2016-01-01

    The VO2 polymorphs, i.e., VO2(A), VO2(B), VO2(M1) and VO2(R), have a wide spectrum of functionalities useful for many potential applications in information and energy technologies. However, synthesis of phase pure materials, especially in thin film forms, has been a challenging task due to the fact that the VO2 polymorphs are closely related to each other in a thermodynamic framework. Here, we report epitaxial stabilization of the VO2 polymorphs to synthesize high quality single crystalline thin films and study the phase stability of these metastable materials. We selectively deposit all the phases on various perovskite substrates with different crystallographic orientations. By investigating the phase instability, phonon modes and transport behaviours, not only do we find distinctively contrasting physical properties of the VO2 polymorphs, but that the polymorphs can be on the verge of phase transitions when heated as low as ~400 °C. Our successful epitaxy of both VO2(A) and VO2(B) phases, which are rarely studied due to the lack of phase pure materials, will open the door to the fundamental studies of VO2 polymorphs for potential applications in advanced electronic and energy devices. PMID:26787259

  7. Epitaxial stabilization and phase instability of VO2 polymorphs

    Science.gov (United States)

    Lee, Shinbuhm; Ivanov, Ilia N.; Keum, Jong K.; Lee, Ho Nyung

    2016-01-01

    The VO2 polymorphs, i.e., VO2(A), VO2(B), VO2(M1) and VO2(R), have a wide spectrum of functionalities useful for many potential applications in information and energy technologies. However, synthesis of phase pure materials, especially in thin film forms, has been a challenging task due to the fact that the VO2 polymorphs are closely related to each other in a thermodynamic framework. Here, we report epitaxial stabilization of the VO2 polymorphs to synthesize high quality single crystalline thin films and study the phase stability of these metastable materials. We selectively deposit all the phases on various perovskite substrates with different crystallographic orientations. By investigating the phase instability, phonon modes and transport behaviours, not only do we find distinctively contrasting physical properties of the VO2 polymorphs, but that the polymorphs can be on the verge of phase transitions when heated as low as ~400 °C. Our successful epitaxy of both VO2(A) and VO2(B) phases, which are rarely studied due to the lack of phase pure materials, will open the door to the fundamental studies of VO2 polymorphs for potential applications in advanced electronic and energy devices.

  8. Electrical oscillation in Pt/VO2 bilayer strips

    International Nuclear Information System (INIS)

    We report on the observation of stable electrical oscillation in Pt/vanadium dioxide (VO2) bilayer strips, in which the Pt overlayer serves the dual purposes of heating up the VO2 and weakening the electric field in the VO2 layer. Systematic measurements in an ultrahigh vacuum nanoprobe system show that the oscillation frequency increases with the bias current and/or with decreasing device dimension. In contrast to most VO2-based oscillators reported to date, which are electrically triggered, current-induced Joule heating in the Pt overlayer is found to play a dominant role in the generation of oscillation in Pt/VO2 bilayers. A simple model involving thermally triggered transition of VO2 on a heat sink is able to account for the experimental observations. The results in this work provide an alternative view of the triggering mechanism in VO2-based oscillators

  9. Middleware for Data Visualization in VO-enabled Data Archives

    CERN Document Server

    Zolotukhin, Ivan

    2007-01-01

    We present a middleware for visualization and exploration of complex datasets in a VO framework, that performs interaction between data archives and existing VO client applications using PLASTIC. It comprises: (1) PLASTIC-enabled Java control applet, integrated into archive web-pages and interacting with VO applications; (2) cross-browser compatible JavaScript part managing PLASTIC-aware VO Clients (launch, data manipulation) by means of Java LiveConnect. This (or similar) solution is an essential for the new generation VO-enabled data archives providing access to complex observational and theoretical datasets (3D-spectroscopy, N-body simulations, etc.) through web-interface. Thanks to PLASTIC capabilities it is possible to start all necessary client software with a single-click in the archive query result page in a web-browser. This simplifies the scientific usage of the VO resources and makes it easy even for users with no experience in the VO technologies.

  10. Middleware for Data Visualization in VO-enabled Data Archives

    Science.gov (United States)

    Zolotukhin, I.; Chilingarian, I.

    2008-08-01

    We present middleware for visualization and exploration of complex datasets in a VO framework, that performs interaction between data archives and existing VO client applications using PLASTIC. It comprises: (1) PLASTIC-enabled Java control applet, integrated into archive web-pages and interacting with VO applications; (2) cross-browser compatible JavaScript part managing PLASTIC-aware VO Clients (launch, data manipulation) by means of Java LiveConnect. This (or similar) solution is an essential for the new generation VO-enabled data archives providing access to complex observational and theoretical datasets (3D-spectroscopy, N-body simulations, etc.) through web-interface. Thanks to PLASTIC capabilities it is possible to start all necessary client software with a single-click in the archive query result page in a web-browser. This simplifies the scientific usage of the VO resources and makes it easy even for users with no experience in the VO technologies.

  11. 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).

  12. Biorefinery Technologies for Biomass Conversion Into Chemicals and Fuels Towards Zero Emissions (Review) / Nulles Emisiju Princips Biomasas Konversijas Tehnoloģijās Aizstājot Fosilos Resursus (Pārskata 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 izsīkums, vides piesārņojums un globāla mēroga klimatiskās izmaiņas ir civilizācijas izdzīvošanai būtiski faktori, kas virza pasaules ekonomikas pārmaiņas, atsakoties no nepārtrauktas izaugsmes idejas par labu tādai ekonomikai, kas balstās uz atjaunojošamies resursiem un dažādu tehnoloģiju integrācijemisiju principam atbilstošās ražošanas sistēmās. Saules radiācijas ierosinātajos planētas biosfērā notiekošajos procesos radīto organisko vielu pārstrādes kompleksi, kas operē ievērojot sabalansētu nulles emisiju principu, tiek uzlūkoti kā tās ekonomiskās (ražošanas) struktūras, kurām jānodrošina pāreja uz atjaunojošos resursu izmantošanu, aizstājot esošās fosilo resursu (naftas, ogļu) pārstrādes rūpnīcas. Līdzās jau apgūtajām biomasas rafinēšanas tehnoloģijām svarīga un pieaugoša loma ekonomiskās sistēmas resursu bāzes nomaiņā ir bio- un nanotehnoloģijām, bet ražošanas sistēmu projektēšanai - biomasas konversijas tehnoloģiju klasterizācijā. Aplūkojot virkni konkrētu tehnoloģisko risinājumu, TSA - biomasas autohidrolīzi tvaika sprādzienā tai skaitā, iztirzātas ar biomasas konversiju, izmantošanu un augstas pievienotās vērtības produktiem - ķīmiskiem savienojumiem un degvielām, saistītās ekololoģiskās un energoefektivitātes problēmas. Uzsverot biomasas TSA pirmapstrādes universālo nozīmi dažādo tehnoloģisko kompleksu struktūrā, aplūkota TSA ietekme uz vidi, demonstrējot eMerģijas (enerģētiskās atmiņas) pieeju un „ilgtspējas" indeksu izmantošanu. Lai gan pie sasniegtā tehnoloģiskās attīstības līmeņa un patreizējiem fosilo enerģijas nesēju patēriņa tempiem nav iespējams tos pilnībā aizstāt ar bioenerģiju, bioenerģijas sektora tehnoloģiju pilnveidošana ir svarīga arī bioresursu racionālas izmantošanas un citos aspektos. Latvijas enerģētiskās neatkarības kontekstā būtiska nozīme ir tradicionālo bioenerģijas resursu izmantošanas efektivitātes celšanai un inovatīvo bioenerģijas tehnoloģiju valstiskam atbalstam.u nulles

  13. 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.

  14. VoIP Regulation in Canada

    OpenAIRE

    Marcel Boyer; Catherine Mercier

    2005-01-01

    The CRTC recently released Regulatory Framework for Voice Communication Services using Internet Protocol (Decision 2005-28), Telecom Decision CRTC 2005-28, setting out the details of the appropriate regulatory regime applicable to the provision of VoIP services. We present a brief overview of Decision 2005-28, we then consider the positions of incumbents and competitors, and finally we comment on the above interventions in light of the economic theory of regulation and the theory of strategic...

  15. Lattice relaxation and ferromagnetic character of (LaVO3) m/SrVO3superlattices

    KAUST Repository

    Schuster, Cosima B.

    2013-08-01

    The experimental observation that vanadate superlattices (LaVO 3)m/SrVO3 show ferromagnetism up to room temperature (Lüders U. et al., Phys. Rev. B, 80 (2009) 241102(R)) is investigated by means of density functional theory, and the band structure for m = 5 and 6 is calculated. A buckling of the interface VO2 layers is found in both cases, but subtle differences in bond length lead to very different properties for even and odd values of m: in the even case, the two interface VO2 layers effectively decouple from the adjacent LaO layers due to a strong bond length enhancement. This results into a local inversion of the orbital occupancy and to the confinement of the charge carriers. In the odd case, the amplitude of the bond length variation is smaller, so that the charge carriers spill into the deeper-lying VO2 layers, and spin-polarised interfaces are obtained. © Copyright EPLA, 2013.

  16. Facile synthesis and high activity of novel BiVO{sub 4}/FeVO{sub 4} heterojunction photocatalyst for degradation of metronidazole

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jinhai [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); School of Chemical Engineering, Guizhou University of Engineering Science, Bijie 551700 (China); Zhao, Wei; Guo, Yang; Wei, Zhongbo; Han, Mengshu [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); He, Huan [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); School of Public Health, University of Illinois at Chicago, Chicago, IL 60631 (United States); Yang, Shaogui [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824 (United States); Sun, Cheng, E-mail: envidean@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China)

    2015-10-01

    Graphical abstract: - Highlights: • BiVO{sub 4}/FeVO{sub 4} was synthesized by a facile one-step hydrothermal method. • BiVO{sub 4}/FeVO{sub 4} displays superior photocatalytic activity. • The photocatalytic mechanism were discussed in detail. - Abstract: The novel BiVO{sub 4}/FeVO{sub 4} heterojunction photocatalyst was successfully synthesized by a facile hydrothermal method firstly. The physical and chemical properties of as-prepared samples were characterized based upon XRD, XPS, BET, SEM, EDS, TEM, UV–vis DRS and fluorescence spectrum techniques. The TEM images showed a clear interface between BiVO{sub 4} and FeVO{sub 4}, indicating that a heterojunction between BiVO{sub 4} and FeVO{sub 4} was formed during the hydrothermal reaction. In addition, the photodegradation activity of metronidazole (MNZ) was used as a measurement for photocatalytic performance of BiVO{sub 4}, FeVO{sub 4} and BiVO{sub 4}/FeVO{sub 4} heterojunction photocatalyst. It indicated that under visible light irradiation the photocatalytic activity of BiVO{sub 4}/FeVO{sub 4} heterojunction photocatalyst was very effective, and moreover, much higher than the single BiVO{sub 4} or single FeVO{sub 4}. The possible photocatalytic mechanism has been discussed on the basis of the theoretical calculation of the electronic structure, and the experimental results.

  17. Facile synthesis and high activity of novel BiVO4/FeVO4 heterojunction photocatalyst for degradation of metronidazole

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • BiVO4/FeVO4 was synthesized by a facile one-step hydrothermal method. • BiVO4/FeVO4 displays superior photocatalytic activity. • The photocatalytic mechanism were discussed in detail. - Abstract: The novel BiVO4/FeVO4 heterojunction photocatalyst was successfully synthesized by a facile hydrothermal method firstly. The physical and chemical properties of as-prepared samples were characterized based upon XRD, XPS, BET, SEM, EDS, TEM, UV–vis DRS and fluorescence spectrum techniques. The TEM images showed a clear interface between BiVO4 and FeVO4, indicating that a heterojunction between BiVO4 and FeVO4 was formed during the hydrothermal reaction. In addition, the photodegradation activity of metronidazole (MNZ) was used as a measurement for photocatalytic performance of BiVO4, FeVO4 and BiVO4/FeVO4 heterojunction photocatalyst. It indicated that under visible light irradiation the photocatalytic activity of BiVO4/FeVO4 heterojunction photocatalyst was very effective, and moreover, much higher than the single BiVO4 or single FeVO4. The possible photocatalytic mechanism has been discussed on the basis of the theoretical calculation of the electronic structure, and the experimental results

  18. Oxidizing annealing effects on VO2 films with different microstructures

    International Nuclear Information System (INIS)

    Vanadium dioxide (VO2) films have been prepared by direct-current magnetron sputter deposition on m-, a-, and r-plane sapphire substrates. The obtained VO2 films display different microstructures depending on the orientation of sapphire substrates, i.e. mixed microstructure of striped grains and equiaxed grains on m-sapphire, big equiaxed grains on a-sapphire and fine-grained microstructure on r-sapphire. The VO2 films were treated by the processes of oxidation in air. The electric resistance and infrared transmittance of the oxidized films were characterized to examine performance characteristics of VO2 films with different microstructures in oxidation environment. The oxidized VO2 films on m-sapphire exhibit better electrical performance than the other two films. After air oxidization for 600 s at 450 °C, the VO2 films on m-sapphire show a resistance change of 4 orders of magnitude over the semiconductor-to-metal transition. The oxidized VO2 films on a-sapphire have the highest optical modulation efficiency in infrared region compared to other samples. The different performance characteristics of VO2 films are understood in terms of microstructures, i.e. grain size, grain shape, and oxygen vacancies. The findings reveal the correlation of microstructures and performances of VO2 films, and provide useful knowledge for the design of VO2 materials to different applications

  19. SPECTRUL AMINOACIZILOR ÎN BIOMASA ALGEI CIANOFITE NOSTOC FLAGELLIFORME (BERK ET CURT) ELENK. CULTIVATE PE MEDIUL DREW

    OpenAIRE

    Irina STRATULAT; Sergiu DOBROJAN; Victor ŞALARU; Vasile ŞALARU; Galina DOBROJAN

    2016-01-01

    A fost studiat spectrul cantitativ şi calitativ al aminoacizilor în biomasa tulpinii Nostoc flagelliforme cultivate pe mediul nutritiv Drew. S-a constatat că biomasa algei Nostoc flagelliforme posedă cantităţi semnificative de aminoacizi, printre care aminoacizii neesenţiali constituie 10,1565 mg/100 mg, iar cei esenţiali se găsesc în cantităţi mai reduse – 7,31 mg/100 mg. De asemenea, au fost evidenţiaţi aminoacizii proteinogeni (17,4476 mg/100 mg) şi imunoactivi (9,5518 mg/100 mg). SPECTRUM...

  20. ESA Science Archives and associated VO activities

    Science.gov (United States)

    Arviset, Christophe; Baines, Deborah; Barbarisi, Isa; Castellanos, Javier; Cheek, Neil; Costa, Hugo; Fajersztejn, Nicolas; Gonzalez, Juan; Fernandez, Monica; Laruelo, Andrea; Leon, Ignacio; Ortiz, Inaki; Osuna, Pedro; Salgado, Jesus; Tapiador, Daniel

    ESA's European Space Astronomy Centre (ESAC), near Madrid, Spain, hosts most of ESA space based missions' scientific archives, in planetary (Mars Express, Venus Express, Rosetta, Huygens, Giotto, Smart-1, all in ESA Planetary Science Archive), in astronomy (XMM-Newton, Herschel, ISO, Integral, Exosat, Planck) and in solar physics (Soho). All these science archives are operated by a dedicated Science Archives and Virtual Observatory Team (SAT) at ESAC, enabling common and efficient design, development, operations and maintenance of the archives software systems. This also ensures long term preservation and availability of such science archives, as a sustainable service to the science community. ESA space science data can be accessed through powerful and user friendly user interface, as well as from machine scriptable interface and through VO interfaces. Virtual Observatory activities are also fully part of ESA archiving strategy and ESA is a very ac-tive partner in VO initiatives in Europe through Euro-VO AIDA and EuroPlanet and worldwide through the IVOA (International Virtual Observatory Alliance) and the IPDA (International Planetary Data Alliance).

  1. Data Analysis Products from VO-India

    Science.gov (United States)

    Deshpande, M.; Moosani, V.

    2009-09-01

    Virtual Observatory, India (VO-India) is a part of the world wide virtual Observatory effort with a mission to develop tools for search, retrieval and analysis of astronomy data. This talk would focus on the tools VOPlot, VOStat and VOCat developed as a part of the VO-India effort. Following is a short description of the tools. VOPlot is a very easy to use menu driven visualization tool. It enables the user to make 2-dimensional and 3-dimensional scatter plots, histograms and surface plots. VOPlot seamlessly integrates with VO-Stat, ALADIN and other tools, to provide an elegant, powerful and yet simple and intuitive environment for the analysis of astronomical catalogues. VOMegaPlot, a functionally restricted version of VOPlot enables users to make 2D plots of millions of points. VOStat is a tool for statistical analysis of astronomical data. The tool uses a public domain statistics software package called `R'. The tests provided by VOStat are grouped into subsets, and can be accessed through a simple graphical interface. VOCat tool provides interface for catalog data. User can export catalogs in ASCII or VOTable ( teauthor{moosaniv_Ochsenbein2008} teyear{moosaniv_Ochsenbein2008}) format to a database and query the data using form or SQL interface. Query output can be sent to tools and services like VOPlot, VOStat, NED, Simbad and Aladin.

  2. What are suspicious VoIP delays?

    CERN Document Server

    Mazurczyk, Wojciech; Szczypiorski, Krzysztof

    2010-01-01

    Voice over IP (VoIP) is unquestionably the most popular real-time service in IP networks today. Recent studies have shown that it is also a suitable carrier for information hiding. Hidden communication may pose security concerns as it can lead to confidential information leakage. In VoIP, RTP (Real-time Transport Protocol) in particular, which provides the means for the successful transport of voice packets through IP networks, is suitable for steganographic purposes. It is characterised by a high packet rate compared to other protocols used in IP telephony, resulting in a potentially high steganographic bandwidth. The modification of an RTP packet stream provides many opportunities for hidden communication as the packets may be delayed, reordered or intentionally lost. In this paper, to enable the detection of steganographic exchanges in VoIP, we examined real RTP traffic traces to answer the questions, what do the "normal" delays in RTP packet streams look like? and, is it possible to detect the use of know...

  3. Crecimiento, Abundancia Y Biomasa De Poecilia reticulata En El Lago Urbano Del Parque Tezozomoc De La Ciudad De Mxico

    Directory of Open Access Journals (Sweden)

    G. Elas-Fernndez

    2006-01-01

    Full Text Available Los lagos urbanos tienen importancia esttica, recreativa, cultural y biolgica por albergar organismos generalmente alctonos, como aves, reptiles, insectos y peces, en particular poecilidos, los cuales son muy tolerantes y se reproducen con facilidad. Por lo anterior, el objetivo de este trabajo fue: determinar la variacin en la abundancia y biomasa de Poecilia reticulata en el lago del parque Tezozomoc, as como obtener la ecuacin de crecimiento. Se realizaron muestreos mensuales de julio del ao 2000 a junio del 2001. Se establecieron tres estaciones donde se registraron las siguientes variables fsicas y qumicas; transparencia, alcalinidad, dureza, pH, conductividad, temperatura y turbiedad por mtodos convencionales. Los peces se capturaron con una red de cuchara de marco rectangular de 100 x 50 cm (rea barrida de 0.5 m2, con luz de malla de 0.5 cm. Los organismos se fijaron con formalina al 10 %. Se registraron las siguientes variables morfomtricas de los organismos; peso (gr y longitud patrn (mm. Se calcul la abundancia y biomasa, as como la ecuacin de crecimiento de acuerdo al modelo de Von Bertalanffy. Se encontr que el agua del sistema es templada, turbia, alcalina, dura y somera. La mayor abundancia (6,148 organismos y biomasa (677.28 g se present en la estacin I, caracterizada por la mayor presencia de visitantes al lago que arroja desperdicios alimenticios al sistema. Los meses con mayor abundancia fueron julio (1,483 org y agosto (1,252 org y los de mayor biomasa agosto (145.12 gr y marzo (138.63 gr. La longitud mxima obtenida de 61.55 mm y la tasa de crecimiento de 0.2987 son valores similares a los obtenidos en sistemas naturales.

  4. Control de una planta prototipo de gasificacin de biomasa mediante redes neuronales

    Scientific Electronic Library Online (English)

    Carlos A., Forero Nez; Jos U., Castellanos Contreras; Fabio E., Sierra Vargas.

    Full Text Available Los sistemas de gasificacin 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 caractersticas tpicas del material y por la variacin 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 desempeo 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 600C a 800C en la zona de inyeccin, superando as el problema derivado de la baja transferencia de energa por conduccin a travs del sistema. Cuando se emplea el control en la gasificacin de cuesco, la temperatura promedio se mantuvo constante en 790C, el CO presente en el gas estuvo alrededor de 10% mientras que el CO2 disminuy a 4%. La aplicacin 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 sntesis con menor contenido de CO2. Esto para un pas con gran diversidad de recursos agroindustriales abre la posibilidad de usar estos subproductos en la generacin de energa 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 600C to 800C, 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 790C; 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.

  5. Urchin-like m-LaVO4 and m-LaVO4/Ag microspheres: Synthesis and characterization

    International Nuclear Information System (INIS)

    The semiconductor nanostructures decorated with noble metals have attracted increasing attention due to their interesting physical and chemical properties. In this work, urchin-like monoclinic (m-) LaVO4 microspheres were prepared by a hydrothermal method and used as a template to fabricate Ag nanoparticle-decorated m-LaVO4 composites. The morphology and structure were characterized by transmission electron microscope, high-resolution transmission electron microscope, scanning electron microscope, and energy-dispersive X-ray. It was found that Ag nanoparticles with narrow size distribution were uniformly loaded on urchin-like m-LaVO4 microspheres, and the resulted composite microspheres showed distinct surface plasmon absorption band compared to pure m-LaVO4 microspheres. Photocatalytic activities of as-prepared samples were examined by studying the degradation of methyl orange solutions under visible-light irradiation (> 400 nm). Results clearly showed that urchin-like m-LaVO4/Ag microspheres possess much higher photocatalytic activity than pure m-LaVO4 microspheres and P25. - Highlights: • m-LaVO4/Ag composites microspheres were fabricated by a hydrothermal method. • m-LaVO4 microspheres show higher photocatalytic activity than m-LaVO4 microspheres. • m-LaVO4/Ag microspheres exhibit a good stability

  6. Intrusion detection mechanisms for VoIP applications

    OpenAIRE

    Nassar, Mohamed; 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.

  7. VoIP Traffic Shaping Analyses in Metropolitan Area Networks

    OpenAIRE

    Goleva, Rossitza; Goleva, Mariya; Atamian, Dimitar; Nikolov, Tashko; Golev, Kostadin

    2008-01-01

    This paper represents VoIP shaping analyses in devices that apply the three Quality of Service techniques – IntServ, DiffServ and RSVP. The results show queue management and packet stream shaping based on simulation of the three mostly demanded services – VoIP, LAN emulation and transaction exchange. Special attention is paid to the VoIP as the most demanding service for real time communication.

  8. Perspectivas del potencial energético de la biomasa en el marco global y latinoamericano

    Directory of Open Access Journals (Sweden)

    Julián Rodrigo Quintero González

    2015-06-01

    Full Text Available El calentamiento global y los cambios climáticos que éste conlleva han fomentado desde hace algunos años la exploración de otros tipos de obtención energética para disminuir el uso del combustible fósil, siendo éste último uno de los principales causantes de dicho problema ambiental. El presente artículo expone algunas investigaciones recientes sobre la bioenergía u obtención de energía a partir de biomasa, considerada como energía limpia. Se abarcan temáticas como la bioenergía y sus posibilidades desde el punto de vista energético, teniendo en cuenta las expectativas de producción según su potencial o productividad energética, además del aporte que este tipo de tecnología hace a la disminución de la huella ecológica.

  9. ESTUDIOS TOXICOLOGICOS COMO HERRAMIENTA PARA EVALUAR EL DESEMPENO DE UN REACTOR ANAEROBIO DE BIOMASA INMOVILIZADA

    Directory of Open Access Journals (Sweden)

    TATIANA RODRIGUEZ CHAPARRO

    2010-01-01

    Full Text Available Los efluentes de la Industria de Papel y Celulosa son usualmente tóxicos y mutagénicos. Esa característica se deriva principalmente por la presencia de compuestos xenobióticos formados durante el proceso. Los parámetros globales para el análisis de la calidad del agua como, demanda química de oxigeno, carbón orgánico total, entre otros, no permiten identificar si el potencial toxicológico es remediado después de los tratamientos. El objetivo de este trabajo fue evaluar el desempeño de un reactor anaerobio horizontal de biomasa inmovilizada (RAHBI tratando un efluente real de blanqueamiento de celulosa Kraft, por medio de ensayos de toxicidad (Daphnia similis Ceriodaphnia silvestrii , mutagenicidad y citotoxicidad (Allium cepa L. . Los resultados mostraron alta sensibilidad de todos los organismos estudiados y buena capacidad del reactor anaerobio para remover compuestos que ejercen efectos tóxicos y mutagénicos. Los bioensayos estudiados representan una alternativa interesante para el análisis de la calidad del agua y para la evaluación del desempeño de tratamientos.

  10. Recuperacin de la biomasa mediante la sucesin 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 informacin sobre el tiempo requerido para recuperar la biomasa area y subterrnea de los primarios. Por lo tanto, establecimos 33 parcelas de 0.1ha entre 550 y 1 700m en bosques secundarios que cubran estadios serales de 3 a 36 aos y estimamos la biomasa de las plantas y de las races gruesas con ecuaciones locales. As como la biomasa de las pasturas y barbechos por cosecha de 54 y 18 parcelas, respectivamente. Tambin se calcul la edad de las parcelas con informantes locales, sensores remotos, C14 y anillos de crecimiento. En cada parcela medimos la biomasa area viva por hectrea (Bav y la de las races gruesas por hectrea (Brg. Modelamos la Bav y Brg en funcin de la edad mediante la ecuacin de von Bertalanfy con asntotas de 247t/ha (Bav y 66t/ha (Brg resultantes de la medicin de 33 parcelas de 0.1ha en los bosques primarios. Con la razn Brg/Bav=f(t estimamos 87 aos para que los bosques secundarios recuperen la Bav existente en los primarios y 217 aos para recuperar la Brg. La tasa mxima de crecimiento instantneo de la Bav fue 6.95t/ha/ao a los 10 aos y la tasa media mxima de crecimiento 6.26t/ha/ao a los 17 aos. La media ponderada de la tasa de crecimiento absoluto de la Bav alcanz 4.57t/ha/ao y la relativa 10% anual. La razn Brg/Bav inicialmente aumenta muy aceleradamente hasta 4-5 aos (25%, luego disminuye hasta 25 aos (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.

  11. Assessing the security of VoIP Services

    OpenAIRE

    Abdelnur, Humberto; State, Radu; Chrisment, Isabelle; Popi, Cristian

    2007-01-01

    VoIP networks are in a major deployment phase and are becoming widely spread out due to their extended functionality and cost efficiency. Meanwhile, as VoIP traffic is transported over the Internet, it is the target of a range of attacks that can jeopardize its proper functionality. In this paper we describe our work in a VoIP specific security assessment framework. Such an assessment is automated with integrated discovery actions, data management and security attacks allowing to perform VoIP...

  12. 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 of the fact that ...

  13. Audio Codecs in VoIPv6: A Performance Analysis

    OpenAIRE

    Monjur Ahmed; Mohammad Sarwar Hossain Mollah

    2014-01-01

    Audio communications in IP based networks have been revolutionized by the introduction of VoIP applications. High cost-efficiency has made VoIP to be the communication means in today’s world; and this trend is anticipated to be continued on an ongoing basis. The performance of VoIP significantly depends on the efficiency of the audio codecs used in any communication scenario which make the study on the performance issues of audio codecs in VoIP applications worth investigating. IPv6 is the ne...

  14. Evaluation of VoIP Security for Mobile Devices

    OpenAIRE

    Nakarmi, Prajwol Kumar

    2011-01-01

    Market research reports by In-Stat, Gartner, and the Swedish Post and Telecom Agency (PTS) reveal a growing worldwide demand for Voice over IP (VoIP) and smartphones. This trend is expected to continue over the coming years and there is wide scope for mobile VoIP solutions. Nevertheless, with this growth in VoIP adoption come challenges related with quality of service and security. Most consumer VoIP solution, even in PCs, analog telephony adapters, and home gateways, do not yet support media...

  15. VO-Dance an IVOA tools to easy publish data into VO and it's extension on planetology request

    Science.gov (United States)

    Smareglia, R.; Capria, M. T.; Molinaro, M.

    2012-09-01

    Data publishing through the self standing portals can be joined to VO resource publishing, i.e. astronomical resources deployed through VO compliant services. Since the IVOA (International Virtual Observatory Alliance) provides many protocols and standards for the various data flavors (images, spectra, catalogues ), and since the data center has as a goal to grow up in number of hosted archives and services providing, the idea arose to find a way to easily deploy and maintain VO resources. VO-Dance is a java web application developed at IA2 that addresses this idea creating, in a dynamical way, VO resources out of database tables or views. It is structured to be potentially DBMS and platform independent and consists of 3 main tokens, an internal DB to store resources description and model metadata information, a restful web application to deploy the resources to the VO community. It's extension to planetology request is under study to best effort INAF software development and archive efficiency.

  16. Risk analysis on VoIP systems

    OpenAIRE

    Knútur Birgir Otterstedt 1984

    2011-01-01

    The goal of this thesis was to perform a risk analysis on a VoIP system for service providers. Main threats of the system were analysed and subsequently each threat was briefly introduced. Assets of the system were analysed, for the risk analysis, and probability of threat and impact of threat estimated (On the scale from low-immense). Next the risk analysis was performed, in software called RM-Studio, and the results analysed. Equivalent analysis was performed for the PSTN system for comp...

  17. VO-compliant workflows and science gateways

    Science.gov (United States)

    Castelli, G.; Taffoni, G.; Sciacca, E.; Becciani, U.; Costa, A.; Krokos, M.; Pasian, F.; Vuerli, C.

    2015-06-01

    Workflow and science gateway technologies have been adopted by scientific communities as a valuable tool to carry out complex experiments. They offer the possibility to perform computations for data analysis and simulations, whereas hiding details of the complex infrastructures underneath. There are many workflow management systems covering a large variety of generic services coordinating execution of workflows. In this paper we describe our experiences in creating workflows oriented science gateways based on gUSE/WS-PGRADE technology and in particular we discuss the efforts devoted to develop a VO-compliant web environment.

  18. New open-framework in the uranyl vanadates A3(UO2)7(VO4)5O (A=Li, Ag) with intergrowth structure between A(UO2)4(VO4)3 and A2(UO2)3(VO4)2O

    International Nuclear Information System (INIS)

    New uranyl vanadates A3(UO2)7(VO4)5O (M=Li (1), Na (2), Ag (3)) have been synthesized by solid-state reaction and their structures determined from single-crystal X-ray diffraction data for 1 and 3. The tetragonal structure results of an alternation of two types of sheets denoted S for ?2[UO2(VO4)2]4- and D for ?2[(UO2)2(VO4)3]5- built from UO6 square bipyramids and connected through VO4 tetrahedra to ?1[U(3)O5-U(4)O5]8- infinite chains of edge-shared U(3)O7 and U(4)O7 pentagonal bipyramids alternatively parallel to a- and b-axis to construct a three-dimensional uranyl vanadate arrangement. It is noticeable that similar ?[UO5]4- chains are connected only by S-type sheets in A2(UO2)3(VO4)2O and by D-type sheets in A(UO2)4(VO4)3, thus A3(UO2)7(VO4)5O appears as an intergrowth structure between the two previously reported series. The mobility of the monovalent ion in the mutually perpendicular channels created in the three-dimensional arrangement is correlated to the occupation rate of the sites and by the geometry of the different sites occupied by either Na, Ag or Li. Crystallographic data: 293 K, Bruker X8-APEX2 X-ray diffractometer equipped with a 4 K CCD detector, MoK?, ?=0.71073 A, tetragonal symmetry, space group P4-bar m2, Z=1, full-matrix least-squares refinement on the basis of F2; 1,a=7.2794(9) A, c=14.514(4) A, R1=0.021 and wR2=0.048 for 62 parameters with 782 independent reflections with I?2?(I); 3, a=7.2373(3) A, c=14.7973(15) A, R1=0.041 and wR2=0.085 for 60 parameters with 1066 independent reflections with I?2?(I). - Abstract: A view of the three-dimensional structure of Li3(UO2)7(VO4)5O. Display Omitted

  19. 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)

  20. Evaluacin de dos mtodos para la estimacin de biomasa arbrea a travs de datos Landsat TM en Jusnajab La Laguna, Chiapas, Mxico: estudio de caso

    Directory of Open Access Journals (Sweden)

    Jorge Escandn Caldern

    1999-01-01

    Full Text Available Se evaluaron dos mtodos para estimar biomasa arbrea con apoyo en sensores remotos (LANDSAT TM. El primer mtodo se realiz con base en una clasificacin supervisada multiespectral con seis bandas Se utilizaron tipos de vegetacin identificados a partir de la composicin de biomasa de os gneros dominantes y de la altura promedio estimada del dosel, habindose distinguido ocho clases de vegetacin. Se obtuvo una biomasa total de 1 073 x 10 3t (902 x 10 3t a 1 220 x 10 3t En el segundo mtodo se utilizaron ndices diferenciados de vegetacin (NDVI de las bandas TM4/TM3; TM4/TM5 y TM4/TM7. Se aplic un modelo de regresin 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 mtodo de clasificacin multiespectral, comparado con los valores estimados por el mtodo de ordenamiento exponencial, mostr mayor similitud con el valor mximo del NDVl que relaciona las bandas TM4/TM7 (de mayor ajuste estadstico y con el valor promedio del NDVl TM4/TM3 (de menor ajuste estadstico. Utilizando el NDVl TM4/TM5, todos los valores de biomasa resultaron ms bajos. De este estudio se concluye que es posible asociar razonablemente la biomasa de vegetacin arbolada de pino-encino y reservorios de carbono con los ndices de vegetacin. A travs del uso de sensores remotos se podran predecir cambios de biomasa en escalas temporales y espaciales.

  1. Phase-Dependent Enhancement of the Green-Emitting Upconversion Fluorescence in LaVO4:Yb(3+), Er(3+).

    Science.gov (United States)

    Zhang, Feng; Li, Guoqiang; Zhang, Weifeng; Yan, Yu Li

    2015-08-01

    The phase-dependent upconversion luminescence properties of LaVO4:Er(3+) were studied to provide new insights into the design of new upconversion materials with high efficiency. Er(3+)-, Yb(3+)/Er(3+)-doped t-LaVO4 microcrystals were successfully synthesized by the disodium ethylenediaminetetraacetic acid (Na2EDTA)-assisted hydrothermal method. X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometer (ICP-OES), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, luminescence spectroscopy, and thermogravimetric analysis (TGA) were used to characterize the samples. The results indicated that t-LaVO4 presents sheaf-like morphology, and the possible formation mechanism for these sheaves was proposed on the basis of time-dependent experiments. Furthermore, the phase-dependence (i.e., monoclinic- and tetragonal-type) upconversion luminescence properties were systematically studied, and the upconversion mechanisms were proposed according to spectral, pump power, and the concentration of Yb(3+) dependence analyses. It is worthwhile pointing out that the Er(3+)-doped t-LaVO4 exhibits a brighter green emission, which is approximately 10 times that of m-LaVO4:Er(3+) using a continuous 980 nm laser diode as the excitation source. This remarkable improvement was rationally analyzed on the basis of the composition, crystal structures, Raman spectra, morphology, and size. The comparative experiments suggest that the local structure of Er(3+) was considered as an important reason for the higher fluorescence intensity of t-LaVO4:Er(3+), which was also confirmed by the results of density functional theory (DFT) calculations. PMID:26203901

  2. 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

  3. VO2(B) nanospheres: Hydrothermal synthesis and electrochemical properties

    International Nuclear Information System (INIS)

    Monodisperse VO2(B) nanospheres with an average size of 100 nm were synthesized by hydrothermal method. Experiments showed that the surfactant octadecyl-amine played an important role during the formation of the nanospheres, and possible mechanism was suggested. Moreover, the potential uses of VO2 nanospheres were primarily probed as electrodes for lithium-ion batteries.

  4. Hydrothermal synthesis and electrochemical characterization of VO{sub 2} (B) with controlled crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Wentao; Ni Juan [Key Laboratory of Polar Materials and Devices (Ministry of Education of China), Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Yu Ke, E-mail: yk5188@263.net [Key Laboratory of Polar Materials and Devices (Ministry of Education of China), Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Zhu Ziqiang [Key Laboratory of Polar Materials and Devices (Ministry of Education of China), Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

    2011-02-01

    Three different VO{sub 2} (B) nanostructures, including urchin-like VO{sub 2} (B), VO{sub 2} (B) honeycombs and VO{sub 2} (B) nanorods have been successfully fabricated through hydrothermal process by adjusting the concentrations of the oxalic acid. The microstructure and morphology of the VO{sub 2} nanostructures were evaluated by using X-ray diffraction and scanning and transmission electron microscopies. Electrochemical properties measurements of urchin-like VO{sub 2} (B) and VO{sub 2} (B) honeycombs showed excellent cycling performance, especially the urchin-like VO{sub 2} (B) exhibited higher discharge capacity and better capacity retention.

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

    Scientific Electronic Library Online (English)

    Maria Isabel, Criales-Hernndez; Camilo, B. Garca; Matthias, Wolff.

    2006-12-01

    Full Text Available La Guajira es un ecosistema de surgencia explotado en la costa del Caribe colombiano. Con el propsito de integrar la informacin disponible sobre el sistema se construy un modelo trfico 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/km/ao, la produccin primaria neta del sistema es de 1 248.51 t/km/ao y las transferencias totales del sistema son de 3 275 t/km/ao, lo que indica un ecosistema con una surgencia moderada comparada con otros sitios. Las mayores transferencias de energa se dan del nivel trfico I-II (68.93 %), aunque existe una importante proporcin 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 relacin P/R excede a 1 y est 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 bsicos 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 an informacin adecuada; especialmente en los valores de biomasa del fitoplancton, invertebrados, bagres, peces depredadores pelgicos, as como estimaciones de produccin en invertebrados, peces depredadores pelgicos y peces pequeos pelgicos. No existe una cuantificacin de las poblaciones de mamferos y aves en el rea 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/km/year), net system production (1248.5 t/km/year), and total system throughput (3 275 t/km/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

  6. Efecto de la salinidad sobre el aceite esencial y la biomasa de dos genotipos de orégano (Origanum spp. cultivados en invernáculo

    Directory of Open Access Journals (Sweden)

    Collado, C.E.

    2012-01-01

    Full Text Available In arid or semi-arid zones, where the quality and/or quantity of water available for watering is inadequate to eliminate the excess of soluble salts, the soil salinity could affect the yield and/or quality of oregano crops. The objective of this study is to evaluate the productivity of biomass and essential oils of two genotypes of oregano when exposed to five different levels of water salinity. An experiment was carried out in pots with a completely random design and four replications. The plants were grown in a greenhouse in sandy-loam soil. They were irrigated with water salinized with NaCl, CaCl2 and MgCl2 with levels of electric conductivity (EC of 2, 4, 6 and 8 dS·m-1 and a control of 0.35 dS·m-1 (no salt added. After 90 days the plants were harvested, and the biomass of the different organs was measured, as well as the yield and concentration of the essential oils in the leaves. The genotype Origanum vulgare L. sp. viridulum yielded a 40 % or more leaves and more than double the essential oil than Origanum x majoricum Cambess for the majority of the EC measurements. If these results are similar to field experiments, the use of O. vulgare with respect to O. x majoricum would be recommendable for both leaf and essential oil yields with salinity of up to 6 dS·m-1, in the first harvest.------------------------------------------------------------------------------------------ En zonas áridas o semiáridas donde la calidad y/o cantidad de agua de riego es inadecuada para eliminar el exceso de sales solubles, la salinidad podría afectar el rendimiento y/o calidad de los cultivos de orégano. El objetivo de este trabajo fue evaluar la productividad en biomasa y aceite esencial de dos genotipos de orégano ante cinco niveles de salinidad. Se realizó un experimento en macetas con un DCA en arreglo factorial y cuatro repeticiones. Las plantas se cultivaron bajo invernáculo, en un suelo de textura franco-arenosa, regándose con agua salinizada con NaCl, CaCl2 yMgCl2 con niveles de conductividad eléctrica (CE de 2, 4, 6 y 8 dS·m-1 y un testigo 0,35 dS·m-1 (sin agregado de sal. A los 90 días las plantas fueron cosechadas determinándose: la biomasa de los diferentes órganos y rendimiento y concentración del aceite esencial en hojas. El genotipo Origanum vulgare L. sp. viridulum rindió 40 % o más de hojas y más del doble de aceite esencial que Origanum x majoricum Cambess para la mayoría de las condiciones de CE. Si estos resultados se mantienen en ensayos a campo, el uso de O. vulgare con respecto a O. x majoricum sería recomendable tanto para rendimiento de hojas como de aceite, con salinidades de hasta 6 dS·m-1, en la primer cosecha.

  7. Monitorování provozu VoIP pomocí technologie OnePK

    OpenAIRE

    Spišiak, Matej

    2014-01-01

    Tato bakalářská práce se zabývá novou proprietární technologií od Cisco Systems zvanou OnePK (One Platform Kit). Soustřeďuje se na možnosti použití v oblasti zberu statistických dat o VoIP provozu. Používá DataPath service set, ktorý zabezpečuje sběr paketů ze síťových zařízení firmy Cisco. DataPath service set posílá pakety na vstup aplikace, která tvoří VoIP statistiku z příchozích SIP paketů. Tato aplikace a provedené testy na technologii OnePK jsou výsledky této práce....

  8. Fabrication of VO2-based multilayer structure with variable emittance

    International Nuclear Information System (INIS)

    Highlights: • Multilayer structures consisted of VO2 layer, HfO2 layer and Ag layer. • Influence of VO2 and HfO2 layer thickness on the emittance variability was studied. • Emittance variation of 0.55 and transition temperature (Tc) of 58 °C was obtained. • Multilayer structures with W-doped VO2 film were deposited. • Influence of W doping concentration on emittance variability was investigated. - Abstract: VO2 film holds promise for smart radiation device (SRD) use because of its infrared reflection change through the semiconductor-to-metal transition (SMT). In present study, a multilayer structure which consisted of VO2 layer, HfO2 layer and Ag layer was fabricated to achieve variable emittance based on the principle of reflection filter and SMT of VO2. It was found that with optimal 50 nm-thick VO2 layer, emittance of the multilayer structure could reversibly change from 0.13 at 30 °C to 0.68 at 80 °C with emittance variability of 0.55. Emittance hysteresis loop with transition temperature (Tc) of 58 °C and narrow width of 4 °C was obtained. Finally, multilayer structures with W-doped VO2 films were deposited and transition temperature decreased from 58 to 5 °C as W doping concentration increased from 0% to 3%, with Tc decreasing efficiency of −17.2 °C/at%. However, W doping also led to increased low temperature infrared absorption of VO2 film, which resulted in decreased emittance variability for the multilayer structure, from 0.55 to 0.37 as the W doping concentration in VO2 layer increase from 0% to 3%

  9. 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.

  10. COMPETENCIA POR SUSTRATO DURANTE EL DESARROLLO DE BIOMASA SULFATORREDUCTORA A PARTIR DE UN LODO METANOGNICO EN UN REACTOR UASB

    Directory of Open Access Journals (Sweden)

    Marisol GALLEGOS-GARCA

    2010-01-01

    Full Text Available En este trabajo se estudi la competencia entre microorganismos metanognicos y sulfatorreductores utilizando un reactor anaerobio de lecho de lodo granular con flujo ascendente (UASB a escala laboratorio, el cual fue usado para el enriquecimiento de biomasa sulfatorreductora a partir de un lodo granular de origen metanognico. El reactor se aliment con una mezcla de etanol y acetato, la carga orgnica se increment de 0.5 a 2 g de demanda qumica de oxgeno (DQO/L-d a pH de 7.0. El consumo de DQO fue mayor a 90 % y la alcalinidad producida por la oxidacin del sustrato increment el pH en el efluente hasta 8.0. A partir de los 50 das de operacin, el reactor se aliment con lactato y sulfato para promover la sulfatorreduccin. La carga orgnica se aument de 1 a 3 g DQO/L-d con una relacin DQO/Sulfato de 0.67 a un tiempo de retencin hidrulico de un da. A los 194 das de operacin del reactor el mximo consumo de DQO y sulfato obtenido fue de 94 y 22 %, respectivamente. La concentracin total del sulfuro alcanzada fue de 310 mg S2-/L y la actividad sulfatorreductora de la biomasa fue de 0.29 g DQO-H2S/g SSV-d, lo que mostr el desarrollo de biomasa sulfatorreductora. La actividad metanognica que se obtuvo fue de 0.35 g DQO-CH4/g SSV-d, estos resultados mostraron que los organismos metanognicos no fueron desplazados por las bacterias sulfatorreductoras, coexistiendo ambos tipos de microorganismos en el lodo granular anaerobio al final de la operacin del reactor.

  11. Dinmica del bosque, incorporacin y almacenamiento de biomasa y carbono en el Parque Nacional Noel Kempff Mercado

    Directory of Open Access Journals (Sweden)

    Alejandro Araujo Murakami

    2006-07-01

    Full Text Available El presente estudio se realiz en dos reas permanentes de investigacin, cada una compuesta por dos parcelas permanentes de medicin, una en un bosque hmedo siempre verde (BHSV y la otra en un bosque seco semideciduo (BSS. Para conocer la dinmica en ambos bosques se calcul la mortalidad anual en funcin al nmero de individuos, la cual es de 2.09% ao en el BHSV y de 2.94% en el BSS y en funcin al rea basal, es de 1.59% en el BHSV y 3.76% en el BSS. Este ltimo valor determin una edad de cohorte de 523 aos en el BHSV y de 164 aos en el BSS. Igualmente se determin el incremento peridico anual diamtrico (IPAD, que es de 0.23 cm/ao en el BHSV y de 0.43 cm/ao en el BSS; con estos ltimos se proyect el crecimiento a travs del mtodo de los tiempos de pasos y tiempos acumulados o tiempo necesario para que cada individuo de 10 cm alcance el tamao mximo, calculando 518 aos para el BHSV y 292 aos para el BSS. La biomasa y el carbono almacenado se estim a travs de funciones matemticas que tienen como variable independiente al rea basal, estimando 326 tn/ha de biomasa y 156 tn/ha de carbono en el BHSV y 260 tn/ha de biomasa y 125 tn/ha de carbono en el BSS. Tambin se estim la incorporacin de carbono por medio del cambio producido en el rea basal, resultando 1.65 tn/ha/ao en el BHSV y 0.44 tn/ha/ao en el BSS. La estructura de ambos tipos de bosque es constante, los individuos muertos y los ascendidos a la clase inmediata son remplazados por aquellos individuos reclutados que mantienen la estructura del bosque.

  12. Growth and investigation of lamellar crystals NaNbO3

    International Nuclear Information System (INIS)

    Using the crystallization method from solution in Na-Nb2O5-NaVO3 or NaBO2 melts obtained are colourless or lightly coloured lamellar crystals NaNbO3 having a high electrical resistance, significant photosensitivity and clearly expressed ferro- and antiferroelectrical properties

  13. Fractal Nature of Metallic and Insulating Domain Configurations in a VO2 Thin Film Revealed by Kelvin Probe Force Microscopy

    OpenAIRE

    Sohn, Ahrum; Kanki, Teruo; Sakai, Kotaro; Tanaka, Hidekazu; Kim, Dong-Wook

    2015-01-01

    We investigated the surface work function (WS) and its spatial distribution for epitaxial VO2/TiO2 thin films using Kelvin probe force microscopy (KPFM). Nearly grain-boundary-free samples allowed observation of metallic and insulating domains with distinct WS values, throughout the metalinsulator transition. The metallic fraction, estimated from WS maps, describes the evolution of the resistance based on a two-dimensional percolation model. The KPFM measurements also revealed the fractal na...

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

    OpenAIRE

    Floriberto Solis-Mendoza; Jaime Sahagún-Castellanos; Clemente Villanueva-Verduzco; María Teresa Colinas-León; María del Rosario García-Mateos

    2012-01-01

    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(NO3)2. Se utilizó un diseño experi...

  15. Utilizacin del medio de cultivo UIT-A en la obtencin de biomasa para la identificacin bioqumica micobacteriana

    Directory of Open Access Journals (Sweden)

    LILIAN M. MEDEROS CUERVO

    1995-12-01

    Full Text Available Se compara el medio de cultivo slido UIT-A con el Lowenstein Jensen, para la obtencin de biomasa en el montaje del test bioqumico de identificacin de micobacterias "no tuberculosas" (MNT, con el objetivo de valorar la posibilidad de utilizacin como medio de cultivo para el montaje y anlisis de dichas pruebas bioqumicas. Los resultados obtenidos en los 2 medios de cultivo utilizados fueron iguales, por lo que se recomienda el uso del medio de cultivo UIT-A fundamentalmente para aquellas cepas con crecimiento pobre o escaso.

  16. Gallinaza: un residual avícola como fuente alternativa de nutrientes para producción de biomasa microalgal

    OpenAIRE

    Rosales Loaiza Nestor Luis; Bermúdez José Luis; Moronta Reyna; Morales Ever Darío

    2008-01-01

    La gallinaza puede ser usada como una fuente alternativa de nutrientes para el cultivo de microalgas, proveyendo de biomasa microalgal utilizable como producto final. El objetivo de este trabajo fue evaluar el efecto de la fracción soluble de gallinaza (FSG) a tres diferentes concentraciones (6, 18 y 36%) sobre el crecimiento, la producción de pigmentos y proteínas de la microalga marina Chroomonas sp. y de la microalga de agua dulce Chlorella sorokiniana. La FSG no biodegradada mostró un efe...

  17. Modelación de la gasificación de biomasa en un reactor de lecho fijo

    OpenAIRE

    García Patiño, Harold Jhair

    2011-01-01

    Se realiza la modelación matemática de un reactor de lecho fijo de calentamiento indirecto que tiene en cuenta los procesos de transferencia de calor y de masa y las reacciones químicas que ocurren durante la transformación termoquímica de biomasa a través de los procesos de pirólisis y gasificación. Mediante este modelo se puede predecir la composición de los gases obtenidos y la distribución de temperaturas en el interior del reactor, en cualquier instante de tiempo. El modelo se desarrolla...

  18. 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 (peffect of Heavy smoking 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.

  19. Synthesis, characterization and formation mechanism of metastable phase VO2(A) nanorods

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Pure phases of VO2(B) and VO2(A) were prepared by a facile hydrothermal method. • Belt-like particles prepared at 180 °C was indexed as monoclinic VO2(B) phase. • Rod-like particles prepared at 230 °C was indexed as tetragonal VO2(A) phase. • VO2(A) nanorods resulted from VO2(B) nanobelts by assembly and crystal adjustment. - Abstract: Pure phase VO2(A) nanorods were synthesized via the reduction of V2O5 by oxalic acid during the hydrothermal treatment. Two sets of samples were prepared by varying both system temperature and reaction time under a filling ratio of 0.40 for observing the formation and evolution of VO2(A) nanorods. Structures were characterized by X-ray diffraction, scanning and transmission electron microscopies, respectively. It was found that VO2(B) was firstly formed and then transformed into VO2(A) as the increasing system temperature or extending reaction time. An assembling and following crystal adjustment was proposed for explanation the formation process of VO2(A) from VO2(B). For VO2(A) nanorods, the phase transition temperature of 169.7 °C was higher than that of the VO2(A) bulk, it might be ascribed to the lower crystallinity or nonstoichiometry in VO2(A) nanorods. VO2 nanostructures with controllable phases and properties should find their promising applications in a single VO2 nanodevice

  20. Undoped and doped VO2 films grown from VO(OC3H7)3

    International Nuclear Information System (INIS)

    Thin VO2-containing films have been grown on glass from vanadyl tri-isopropoxide by both chemical vapor deposition (CVD) and gel hydration. Undoped films grown by CVD were used to characterize the near-IR transmittance switching at 680C. Spectral and resistive switching are known to accompany this monoclinic-tetragonal symmetry transition. Relatively large spectral switching occurred within 0.8-2.2 μm even when resistive switching was poor, i.e. less than twofold. The largest resistive switching observed was about 103-fold, which is similar to the best reported elsewhere for VO2 films prepared on glass in other ways. In the case of gel preparation, the films were doped with tungsten, molybdenum or niobium to demonstrate shifting of the transition below 680C. The depression achieved with these films is qualitatively consistent with the conclusions of other researchers that are based on doped VO2 crystals and powders. By comparison with undoped CVD films, however, there is no indication that doping has any unusual effect on IR switching. (Auth.)

  1. Conversión hidrotérmica suscritica de residuos orgánicos y biomasa. mecanismos de reacción

    OpenAIRE

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

    2010-01-01

    La conversión hidrotérmica es un procedimiento que emula el proceso natural de conversión de la materia orgánica en un biocrudo con propiedades fisicoquímicas similares a las del petróleo. La transformación artificial de biomasa requiere conocer previamente las rutas de reacción y productos prevalentes. En la conversión de celulosa, el principal componente de la biomasa, se presenta despolimerización por hidrólisis y se obtienen oli- gosacaridos, los cuales presentan deshidratación y condens...

  2. Actividad y biomasa microbianas como indicadores de materia orgánica en sistemas de cultivo de maracuyá (passiflora edulis) en toro, valle del cauca, colombia

    OpenAIRE

    Sánchez de Prager, Marina; Rojas, Adriana; Pérez, Jesús; Zúñiga, Orlando; Gascó, José María

    2007-01-01

    El estudio evaluó la relación entre materia orgánica del suelo, actividad y biomasa microbianas. Se usaron tres sistemas de cultivo de maracuyá (agroecológico, transición y convencional) en el municipio de Toro (Valle del Cauca). En muestras tomadas al azar en dos profundidades (0-15 y 1530 cm). En nueve puntos por sistema de manejo se midieron propiedades biológicas [actividad microbiana (C-CO2); biomasa microbiana (Cmicro) -fumigación, extracción- y propiedades físicas y químicas (materia o...

  3. Reinvestigation of the synthesis of LiFeVO4

    International Nuclear Information System (INIS)

    Highlights: → We reinvestigated the synthesis of the LiFeVO4 compound. → We demonstrate that the recently reported LiFeVO4 phase is not a pure phase. → We proved by Rietveld refinement that LiFeVO4 is a mixture ofLiVO3 and Fe2O3. → We noticed some attempts to fraud (modification of the powder pattern) . - Abstract: The synthesis of LiFeVO4 composition has been performed in air starting from Li2CO3, Fe2O3, and V2O5 and using the standard solid-state reaction route reported by Refs. . Identical X-ray diffraction pattern has been obtained, however our careful analysis with MDI Jade 5.0 software does not agree with previously reported pure LiFeVO4 samples. The powder pattern has been perfectly indexed using the single crystal data of LiVO3 (C2/c, a = 10.16718 A, b = 8.415725 A, c = 5.884155 A and β = 110.489o) and α-Fe2O3 (R-3c, a = 5.035 A, c = 13.75 A).

  4. SIP-CCME cooperation in multimedia VoIP network

    Science.gov (United States)

    Grądkowska, Magdalena; Popiel, Piotr; Sobańska, Katarzyna

    2006-10-01

    VoIP is a fast-developing technology which allows making telephone calls using a data network like the Internet. VoIP converts the voice signal from the telephone into a digital signal that travels over the Internet and then converts it back at the other end so that speaking to anyone with a regular phone number is possible. VoIP may also enable the direct calls from a computer with the use of a conventional telephone or a microphone. Some services using VoIP may only allow you to call other people using the same VoIP service, but others may allow you to call anyone who has a telephone number. First condition is a broadband Internet connection for VoIP technology to work. There are two major advantages of VOIP: lower cost and increased functionality. In the paper the integration of two networks, one with a CCME based installation and the other with a full Asterisk/SIP voicemail deployment is presented. The goal was to allow dialing between VoIP's telephony from different networks and evaluate a quality of connection with the use of certain codecs.

  5. Efecto de la depuracin en la biomasa del caracol Pomacea patula [Baker, 1922] usando el ndice de condicin

    Directory of Open Access Journals (Sweden)

    M. Garca-Ulloa

    2006-01-01

    Full Text Available La depuracin de organismos acuticos en cultivo es una prctica comn. El tiempo de exposicin de los animales al agua tratada es uno de los factores ms importantes para su eficiencia, pudiendo afectar su biomasa. Se evalu el efecto de la depuracin en adultos de Pomacea patula mediante la aplicacin del ndice de condicin (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 radiacin ultravioleta y limpieza diaria y en condiciones normales de mantenimiento (Grupo 2, con 5 rplicas por grupo. Se obtuvo el peso hmedo y longitud total individualmente, al inicio y despus de una depuracin de 10 das. El valor promedio del coeficiente de correlacin (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 mostr diferencias significativas (P > 0.05 al final del experimento. Los resultados sugieren que el proceso de depuracin usado no afect la biomasa de adultos de P. patula. El IC se mostr como una herramienta prctica de evaluacin sin considerar la diferencia inicial de tallas de caracoles adultos

  6. VoIP Malware: Attack Tool & Attack Scenarios

    OpenAIRE

    Nassar, Mohamed; State, Radu; Festor, Olivier

    2009-01-01

    With the appearance of new Internet services like Voice over IP and IP television, malwares are in the way to update and extend their targets. In this paper, we discuss the emergence of a new generation of malwares attacking VoIP infrastructures and services. Such malwares constitute a real threat to the currently deployed VoIP architectures without strong security measures in place. We present one implemented environment that can be used to evaluate such attacks. Our ``VoIP bots'' support a ...

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

    OpenAIRE

    Brescia, M.; Cavuoti, S.; D'Angelo, G.; d'Abrusco, R.; Deniskina, N.(INFN, Sezione di Napoli, Naples, Italy); Garofalo, M.; Laurino, O.; G. Longo; 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 A...

  8. Thermal properties of a novel compound PbVO3

    International Nuclear Information System (INIS)

    Effect of pressure on thermal properties of a multiferroic (MF) novel compound PbVO3 is studied using an atomistic approach. The temperature dependence of the specific heat (CP) (20K ? T ? 300 K) of PbVO3 has been studied and compared with the earlier experimental work. Also, this work reports, probably for the first time the relation of pressure to the Debye temperature (?D) along with other properties like bulk modulus (B), molecular force constant (f), Reststrahlen frequency (?0), thermal expansion (?) and Grneisen parameter of PbVO3 with the Modified Rigid Ion Model (MRIM).

  9. Room temperature magnetism in LaVO3/SrVO3 superlattices by geometrically confined doping

    OpenAIRE

    Luders, U.; Sheets, W. C; David, A.; Prellier, W.; Fresard, R.

    2009-01-01

    Based on the Hubbard model of strongly correlated systems, a reduction in the bandwidth of the electrons can yield a substantial change in the properties of the material. One method to modify the bandwidth is geometrically confined doping, i.e. the introduction of a (thin) dopant layer in a material. In this paper, the magnetic properties of LaVO$_3$/SrVO$_3$ superlattices, in which the geometrically confined doping is produced by a one monolayer thick SrVO$_3$ film, are presented. In contras...

  10. Tecnologia e forças competitivas: estudo de caso sobre o VoIP em uma concessionária de telecomunicações

    Directory of Open Access Journals (Sweden)

    Renato de Oliveira Moraes

    2010-06-01

    Full Text Available O presente artigo analisa a influência da tecnologia de Voz sobre IP (VoIP nas posições estratégicas, sob a perspectiva da CTBC, utilizando-se da tipologia de Porter. A análise dos dados demonstra que os clientes adquiriram maior poder de barganha, quando se soma a tecnologia VoIP ao surgimento de novos concorrentes do setor de provedores de conteúdos, impulsionando a empresa a realizar alianças com esses provedores. Foi identificado, também, o surgimento de produtos substitutos oferecidos por concorrentes que adquirem a tecnologia de banda larga da própria empresa. Entretanto, esses produtos não interferem significativamente na rentabilidade da empresa, atualmente. Uma última análise aponta que, para clientes residenciais, a tecnologia impactou diretamente na rentabilidade da empresa na telefonia fixa, tendo como principal fator, o aumento das vendas de acesso à Internet por banda larga e o conseqüente aumento da utilização do VoIP por meios não pagos. Pôde-se identificar, com bom grau de clareza, que a tecnologia VoIP para a CTBC é uma questão de sobrevivência futura, possuindo potencialidades para rentabilidade em médio e longo prazos, não representando, porém, diferencial estratégico imediato.

  11. 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.

  12. Disordered LiZnVO4 with a phenacite structure

    Directory of Open Access Journals (Sweden)

    Mohamed Azrour

    2010-05-01

    Full Text Available Single crystals of lithium zinc vanadate, LiZnVO4, were grown by the flux method. The structural type of this vanadate is characterized by a three-dimensional arrangement of tetrahedra sharing apices in an LiZnVO4 network. This arrangement contains three different tetrahedra, namely one [VO4] and two disordered mixed-site [Li/ZnO4] tetrahedra. The resulting lattice gives rise to hexagonal channels running along the [0001] direction. Both sites in the mixed-site [Li/ZnO4] tetrahedra are occupied by a statistical mixture of lithium and zinc with a 1:1 ratio. Therefore, LiZnVO4 appears to be the first vanadate known to crystallize with a disordered phenacite structure. Moreover, the resulting values of calculated bond valences (Li = 1.083, Zn = 2.062 and V = 5.185 tend to confirm the structural model.

  13. Audio CAPTCHA for SIP-Based VoIP

    Science.gov (United States)

    Soupionis, Yannis; Tountas, George; Gritzalis, Dimitris

    Voice over IP (VoIP) introduces new ways of communication, while utilizing existing data networks to provide inexpensive voice communications worldwide as a promising alternative to the traditional PSTN telephony. SPam over Internet Telephony (SPIT) is one potential source of future annoyance in VoIP. A common way to launch a SPIT attack is the use of an automated procedure (bot), which generates calls and produces audio advertisements. In this paper, our goal is to design appropriate CAPTCHA to fight such bots. We focus on and develop audio CAPTCHA, as the audio format is more suitable for VoIP environments and we implement it in a SIP-based VoIP environment. Furthermore, we suggest and evaluate the specific attributes that audio CAPTCHA should incorporate in order to be effective, and test it against an open source bot implementation.

  14. Formation and performances of porous InVO4 films

    International Nuclear Information System (INIS)

    Porous complex oxide films consisting of preferentially orientated orthorhombic phase of InVO4 have been prepared using a novel simple method by pyrolysis of amorphous complex precursor. The formation and controlling of porous InVO4 films can be easily obtained by modifying the calcination temperature. The pure orthorhombic InVO4 phase can be obtained at a relatively lower temperature (500 deg. C), and the films are preferential orientation of the (200) face parallel to the substrate. The phase separation mechanism was suggested for the formation of porous films. Under visible light irradiation (λ>400 nm), porous InVO4 films have shown the photocatalytic activity for photodegradation of gaseous formaldehyde, and can generate photocurrent. The electrochemical properties of the films with different crystal structure and pore structure were also investigated

  15. A European Perspective of VoIP in Market Competition

    OpenAIRE

    FEIJÓO GONZÁLEZ Claudio; GOMEZ-BARROSO Jose-Luis; ROJO-ALONSO David

    2008-01-01

    The debate on the future of VoIP (Voice over Internet Protocol) is not new. For some time now this technological innovation has been considered one of main drivers for reshaping the telecommunications industry. Such is the case that even former Federal Communications Commission Chairman, Michael Powell, said at the Davos World Economic Forum (Switzerland, January 2004) that VoIP ¿is probably the most significant paradigm shift in the entire history of modern communications, since the inventio...

  16. Mathematical Representation of VoIP Connection Delay

    OpenAIRE

    Halas, M.; Baronak, I.

    2007-01-01

    The main topic of this article is to define mathematical formulation of VoIP connection delay model. It handles about all partial delay components, the mechanism of their generation, facilities and their mathematical formulation. Thereafter based on mathematical formulation of all partial delay components, the final mathematical model of whole VoIP call delay is created. In conclusion of this article the results of the designed mathematical model are compared with the experimentally gained re...

  17. Mathematical Representation of VoIP Connection Delay

    Directory of Open Access Journals (Sweden)

    M. Halas

    2007-09-01

    Full Text Available The main topic of this article is to define mathematical formulation of VoIP connection delay model. It handles about all partial delay components, the mechanism of their generation, facilities and their mathematical formulation. Thereafter based on mathematical formulation of all partial delay components, the final mathematical model of whole VoIP call delay is created. In conclusion of this article the results of the designed mathematical model are compared with the experimentally gained results.

  18. VoIP Operators : From a Carrier Point of View

    OpenAIRE

    Sidiropoulou, Christina

    2011-01-01

    Voice over Internet Protocol (VoIP) is a service that has recently gained a lot of attention from the telecommunications (telecom) world since both Internet service providers (ISPs) and telecommunications operators have realized the important advantages that it can offer. Although traditional telephony is well established both in the telecom world and in our daily lives, VoIP is now competing with it by offering cost savings, simplicity, and introducing new ways of communicating. Internet ser...

  19. Update of the China-VO AstroCloud

    OpenAIRE

    Cui, Chenzhou; Yu, CE; Xiao, Jian; He, Boliang; Li, Changhua; Fan, Dongwei; Wang, ChuanJun; Hong, Zhi; Li, Shanshan; Mi, Linying; Wan, Wanghui; Cao, Zihuang; Wang, JiaWei; Yin, Shucheng; Fan, YuFeng

    2016-01-01

    As the cyber-infrastructure for Astronomical research from Chinese Virtual Observatory (China-VO) project, AstroCloud has been archived solid progresses during the last one year. Proposal management system and data access system are re-designed. Several new sub-systems are developed, including China-VO PaperData, AstroCloud Statics and Public channel. More data sets and application environments are integrated into the platform. LAMOST DR1, the largest astronomical spectrum archive was release...

  20. Two-dimensional VO2 photonic crystal selective emitter

    International Nuclear Information System (INIS)

    The design and simulation of a two-dimensional (2D) photonic crystal (PhC) selective emitter made of vanadium dioxide (VO2), a type metal oxide with a high temperature resistance, are reported. Spectral emission characteristics of the 2D VO2 PhCs were investigated using the finite difference time domain (FDTD) method. The PhC consists of a periodic array of cylindrical air microcavities. The influences of the geometric characteristic parameters are discussed. The influences of the radius and depth on the emission of the 2D VO2 PhC can be explained based on the coupled-mode theory. The emissivities at wavelengths below the cut-off wavelength were enhanced by increasing the depth. When the depth was much larger than the radius, the cut-off wavelength increased with the radius. The effect of the period on the emissivity at wavelengths less than the period was highly influenced by the diffraction modes. The designed 2D VO2 PhC emitter exhibited a selective emission that was well-matched with InGaAs cells. The spectral emissivities within the convertible wavelength range of the InGaAs cells reached 0.95, and the emissivities for non-convertible wavelengths were less than 0.3. - Highlights: • The lattice structure of metal phase VO2 does not change with temperature. • The influences of scales on the emission of a 2D VO2 PhC are discussed. • A 2D VO2 photonic crystal emitter matched well with InGaAs cell is designed. • The matched VO2 PhC emitter can highly improve the TPV system efficiency

  1. High pressure phase transitions in NdVO4

    Science.gov (United States)

    Panchal, V.; Errandonea, D.; Manjn, F. J.; Muoz, A.; Rodrguez-Hernndez, P.; Bettinelli, M.; Achary, S. N.; Tyagi, A. K.

    2015-06-01

    Raman-scattering measurements on NdVO4 suggest a pressure-induced zircon to monazite phase transition beyond 5.9 GPa. The monazite phase undergoes a second phase transition to a yet unknown phase at 18.1 GPa. Lattice-dynamics calculations well support the experimental findings and predict a possible orthorhombic structure for the post-monazite structure of NdVO4.

  2. Monitoring Architecture for Lawful Interception in VoIP Networks

    OpenAIRE

    Karpagavinayagam, Balamurugan; State, Radu; Festor, Olivier

    2007-01-01

    Lawful Interception is one of the main provisions needed for the security agencies to monitor a suspect or deal with criminal activities. The implementation of this was easy in the traditional telephone networks, because of its centralized administration. However this has become a tedious job with the emergence of VoIP technologies where voice traffic is carried over IP. In this paper, we discuss the challenges and propose a monitoring architecture for Lawful Interception on VoIP networks bas...

  3. Properties of HoVO4 below 1 K

    International Nuclear Information System (INIS)

    Radio-frequency methods are used to determine the variation with applied magnetic field (up to 7T) of the adiabatic susceptibility of the Van Vleck electronic paramagnet HoVO4, and the magnetic specific heat of the enhanced nuclear system 165HoVO4. The results are in good agreement with values deduced from optical measurements and n.m.r. measurements. (author)

  4. Alkalimetal (Na+ and K+)- mediated supramolecular assembly of oxovanadium(V) complexes: Synthesis and structural characterization

    OpenAIRE

    Dinda, Rupam; Ghosh, Saktiprosad; Falvello, Larry R.

    2010-01-01

    The syntheses and characterization of alkalimetal complexes [{VO2L}M(H2O}n] (1 and 2) [M = Na+ (1), K+ (2)] of anionic cis-dioxovanadium(V) species (LVO2−) of the Schiff base 2-hydroxybenzoylhydrazone of 2-hydroxybenzaldehyde have been reported. The number of coordinated water molecules in [{VO2L}M(H2O}n] decreases as the charge density of the alkalimetal ion decreases (n = 5 for Na+ and 1 for K+). These compounds represented M+-mediatedsupramolecularassembly [{VO2L}M(H2O}n]∝ with an infinite...

  5. The Euro-VO Registry, Re-engineering the Back-end

    Science.gov (United States)

    Arviset, C.; Perdikeas, M.; Osuna, P.; Gonzalez, J.

    2015-09-01

    The Euro-VO Registry, located, developed and operated at ESAC, is one of the full searchable registries available worldwide, gathering information about all VO-compliant resources. The Euro-VO Registry serves as a registration point for European - and other countries- VO actors and data centres wishing to publish VO services. It harvests other registries to ensure its completeness so VO applications developers and VO users can use it to discover all VO resources, from Europe and from all other VO projects. The Euro-VO Registry provides as well a harvesting interface to other registries in the world to make sure the European VO services are also included in all other worldwide full registries. In particular, the new Euro-VO registry will be supporting the new RegTAP search interface for the relational registry allowing arbitrary ADQL queries against its contents over a compliant TAP service. The recently obsolete (for future developments) SOAP-based legacy search interface will also be supported for backwards compatibility purposes. Furthermore, in the context of the IVOA, some quality control and curation procedures for the registry resources are being defined. The Euro-VO Registry implements these procedures to ensure the high quality of the VO resources it references. This paper gives an overview of the recent development of the new Euro-VO Registry, together with its new curation facilities, both of which are being performed under a contract awarded to Neuropublic, under ESA special initiative to Greece.

  6. 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.

  7. The preparation of a plasmonically resonant VO2 thermochromic pigment

    Science.gov (United States)

    Bai, Huaping; Cortie, Michael B.; Maaroof, Abbas I.; Dowd, Annette; Kealley, Catherine; Smith, Geoffrey B.

    2009-02-01

    Vanadium dioxide (VO2) undergoes a reversible metal-insulator transition, normally at ~68 °C. While the properties of continuous semi-transparent coatings of VO2 are well known, there is far less information available concerning the potential use of discrete VO2 nanoparticles as a thermochromic pigment in opaque coatings. Individual VO2 nanoparticles undergo a localized plasmon resonance with near-infrared light at about 1100 nm and this resonance can be switched on and off by simply varying the temperature of the system. Therefore, incorporation of VO2 nanoparticles into a coating system imbues the coating with the ability to self-adaptively modulate its own absorptive efficiency in the near-infrared. Here we examine the magnitude and control of this phenomenon. Prototype coatings are described, made using VO2 powder produced by an improved process. The materials are characterized using calorimetry, x-ray diffraction, high-resolution scanning electron microscopy, transmission electron microscopy, and by measurement of optical properties.

  8. The preparation of a plasmonically resonant VO2 thermochromic pigment

    International Nuclear Information System (INIS)

    Vanadium dioxide (VO2) undergoes a reversible metal-insulator transition, normally at ∼68 0C. While the properties of continuous semi-transparent coatings of VO2 are well known, there is far less information available concerning the potential use of discrete VO2 nanoparticles as a thermochromic pigment in opaque coatings. Individual VO2 nanoparticles undergo a localized plasmon resonance with near-infrared light at about 1100 nm and this resonance can be switched on and off by simply varying the temperature of the system. Therefore, incorporation of VO2 nanoparticles into a coating system imbues the coating with the ability to self-adaptively modulate its own absorptive efficiency in the near-infrared. Here we examine the magnitude and control of this phenomenon. Prototype coatings are described, made using VO2 powder produced by an improved process. The materials are characterized using calorimetry, x-ray diffraction, high-resolution scanning electron microscopy, transmission electron microscopy, and by measurement of optical properties.

  9. Audio Codecs in VoIPv6: A Performance Analysis

    Directory of Open Access Journals (Sweden)

    Monjur Ahmed

    2014-04-01

    Full Text Available Audio communications in IP based networks have been revolutionized by the introduction of VoIP applications. High cost-efficiency has made VoIP to be the communication means in today’s world; and this trend is anticipated to be continued on an ongoing basis. The performance of VoIP significantly depends on the efficiency of the audio codecs used in any communication scenario which make the study on the performance issues of audio codecs in VoIP applications worth investigating. IPv6 is the new version of IP, which will gradually replace the current IPv4 as the transition from IPv4 to IPv6 is already in place. This demands the scrutiny of the audio codecs being used in IPv4 to be tested for their compatibility in IPv6 in terms of desired performance. This paper presents the study on the performance of selected audio codecs that are widely used in VoIPv4. G.711, G.729A and G.723.1 codecs were chosen for the study in VoIPv6 based scenarios presented in this paper. The selected audio codecs were applied in IPv6 based voice communication network scenarios to determine their performance efficiency by observing various QoS parameters. The study was done by means of simulation using OPNET.

  10. Template-Engaged In Situ Synthesis of Carbon-Doped Monoclinic Mesoporous BiVO4: Photocatalytic Treatment of Rhodamine B

    Science.gov (United States)

    Yao, Mingming; Gan, Lihua; Liu, Mingxian; Tripathi, Pranav K.; Liu, Yafei; Hu, Zhonghua

    2015-06-01

    In this paper, carbon-doped monoclinic scheelite mesoporous bismuth vanadate was synthesized through template-engaged in situ method. The bismuth nitrate pentahydrate and ammonia metavanadate were used as bismuth and vanadium precursors, respectively, glucose as carbon source, and mesoporous SiO2 aerogel as a hard template. Carbon-doped monoclinic mesoporous BiVO4 were obtained by heat treatment of BiVO4/glucose/template to carbonize glucose and form monoclinic crystal, followed by etching with NaOH solution to remove the SiO2 template. The samples were characterized by x-ray diffraction, N2 adsorption and desorption, UV-visible spectroscopy, Energy dispersive spectrometry, Raman spectroscopy, and Transmission electron microscopy. It was found that the sample with a carbon content of 0.5 wt.% possesses a specific surface area of 10.2 m2/g and has mesoporous structure with the most probable pore size of 13.9 nm. The band gap of carbon-doped monoclinic mesoporous BiVO4 was estimated to be 2.33 eV, indicating the superior photocatalytic activity under visible light. The photocatalytic efficiency of carbon-doped monoclinic mesoporous BiVO4 for the degradation of Rhodamine B under visible light (λ > 400 nm) in 120 min reaches 98.7%, Besides, the carbon-doped monoclinic mesoporous BiVO4 photocatalyst still showed high stability: 85% for Rhodamine B degradation after ten recycles.

  11. 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.

  12. Efecto de la aplicación de hojarasca de mucuna sobre densidad y biomasa de lombrices de tierra

    Directory of Open Access Journals (Sweden)

    Esperanza Huerta

    2005-01-01

    como ingenieros del ecosistema han mostrado ser una herramienta viable. La Mucuna pruriens var. Utilis (mucuna, leguminosa utilizada en los campos agrícolas tropicales, se usó en este experimento, en dos cantidades, 1.5 y 4.5 kg m-2, en forma de hojarasca, como fuente de materia orgánica fresca, con el fin de incrementar la abundancia de las lombrices de tierra in situ durante un año. Esta hojarasca se aplicó de tres formas: en la superficie, en el interior, y en la superficie y en el interior en un campo de maíz de 30 x 37 m, generando tres tratamientos con 1.5 kg m-2, tres tratamientos con 4.5 kg m-2 y dos testigos: parcelas sin mucuna, un testigo con laboreo y otro testigo sin laboreo; se constituyeron los ocho tratamientos evaluados, mismos que contaron con tres repeticiones, distribuyéndose en bloques al azar en el área experimental. Después de un año de experimentación, en las parcelas donde se adicionó la mucuna se registró la mayor densidad (99.2 ± 44.6 individuos m-2 y biomasas (10.6 ± 5.6 g m-2 de lombrices en cuadrantes donde la Mucuna se aplicó en la superficie, en cantidad de 4.5 kg m-2. Se obtuvo también la mayor producción de maíz (70.3 ± 22.6 g individuos m-2, P < 0.05. El efecto de esta leguminosa no se apreció sobre la especie cosmopolita endogea Polypheretima elongata, la cual presentó su mayor biomasa en los cuadrantes sin mucura (16.8 ± 10.2 g m-2, P < 0.05. Se observó el efecto del laboreo sobre esta lombriz, registrándose la menor biomasa en los cuadrantes sin mucuna y con laboreo (3 ± 0.4 g m-2.

  13. Caracterizacin del bagazo de caa como biomasa vegetal / Characterization of the cane bagasse like vegetable biomass

    Scientific Electronic Library Online (English)

    Enma M., Manals-Cutio; Margarita, Penedo-Medina; Dolores, Salas-Tort.

    2015-08-01

    Full Text Available Este trabajo tiene como finalidad evaluar propiedades fsicas y qumicas de diferentes clases de tamao de muestras de bagazo de caa, como parte del estudio de descomposicin trmica de las mismas. Para la realizacin del anlisis granulomtrico del bagazo de caa se estudiaron dos muestras; obteni [...] ndose una distribucin muy variada, desde un fino polvo hasta partculas irregulares de gran tamao, las mayores acumulaciones fueron obtenidas para partculas menores de 0,5 mm y hasta 1mm de dimetro. En este estudio se desarrollaron dos mtodos: el Mtodo Diferencial y el Mtodo Acumulativo, obtenindose dimetros promedio de las muestras aproximadamente iguales por ambos mtodos, de manera que el dimetro promedio del bagazo de caa en general es de 0,453 mm. Aplicando la metodologa experimental y en las instalaciones adecuadas se evaluaron las propiedades qumicas de la biomasa estudiada: carbono fijo, voltiles, cenizas, humedad. Luego se determin la influencia del tamao de las partculas en las propiedades del bagazo de caa obtenindose que para la humedad y el carbono fijo no existe una tendencia definida en estos parmetros. En el caso del contenido de voltiles existe una tendencia al aumento de este contenido con el aumento del dimetro de las partculas, ocurriendo lo contrario para el contenido de cenizas. Se obtuvo una diferencia estadsticamente significativa entre la media de cada uno de estos parmetros entre un nivel de Dpi y otro, excepto para el caso del carbono fijo. Abstract in english In this work were evaluated physical and chemical properties of different classes of size of samples of bagasse cane, like part of the study of thermal decomposition of the same ones. Two samples were studied; being obtained a very varied distribution, from a fine powder until irregular particles of [...] great size, the biggest accumulations were obtained for particles smaller than 0,5mm and up to 1mm of diameter. In this study two methods were developed: the Differential Method and the Accumulative Method, being obtained diameters average of the approximately same samples by both methods, so that the diameter average of the bagasse cane in general is of 0,453mm. Applying the experimental methodology and in the appropriate facilities the chemical properties of the studied biomass were evaluated: fixed, volatile, ashy carbon, humidity. Then the influence of the size of the particles was determined in the properties of the cane trash being obtained that for the humidity and the fixed carbon doesn't exist a tendency defined in these parameters. In the case of the content of volatile a tendency exists to the increase of this content with the increase of the diameter of the particles, happening the opposite for the content of ashy. A difference was obtained statistically significant among the stocking of each one of these parameters among a level of Dpi and other, except for the case of the fixed carbon.

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

    Directory of Open Access Journals (Sweden)

    Lizet Rodríguez-Machín

    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.

  15. Biomasa de rotíferos de dos embalses con diferentes estados tróficos (Antioquia, Colombia y su relación con algunas variables limnológicas

    Directory of Open Access Journals (Sweden)

    Silvia L Villabona-González

    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 temperatura, 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.

  16. Validade preditiva da medida e estimativas do VO2máx no desempenho de Mountain Bikers

    OpenAIRE

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

    2015-01-01

    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 indireta, 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), for...

  17. Gallinaza: Un residual avícola como fuente alternativa de nutrientes para producción de biomasa microalgal

    Directory of Open Access Journals (Sweden)

    Rosales Loaiza Nestor Luis

    2007-07-01

    Full Text Available La gallinaza puede ser usada como una fuente alternativa de nutrientes para el cultivo de microalgas, proveyendo de biomasa microalgal utilizable como producto final. El objetivo de este trabajo fue evaluar el efecto de la fracción soluble de gallinaza (FSG a tres diferentes concentraciones (6, 18 y 36% sobre el crecimiento, la producción de pigmentos y proteínas de la microalga marina Chroomonas sp. y de la microalga de agua dulce Chlorella sorokiniana. La FSG no biodegradada mostró un efecto letal sobre el crecimiento de ambas microalgas. La FSG tratada aeróbicamente mejoró el crecimiento de Chroomonas sp. a 18% con 131,37 ±13,66 x106 cel mL-1, y a 36% para C. sorokiniana de 228,64 ±4,90 x106 cel mL-1 (p

  18. ESTIMACIÓN DE BIOMASA DE ÓRGANOS AÉREOS DE PLANTAS DE MANZANA CV. AGUA NUEVA 2

    Directory of Open Access Journals (Sweden)

    J. R. Espinoza-Espinoza

    2007-01-01

    Full Text Available La biomasa de órganos de las plantas es una variable muy útil en estudios de crecimiento, relaciones fuente-demanda y productividad. Dado que su medición involucra el secado en estufa, es destructiva por necesidad, lo cual no representa un inconveniente en plantas anuales y de bajo porte, pero sí lo es en plantas grandes, como los frutales, incluido el manzano. En este trabajo se generaron modelos matemáticos mediante regresión, que estiman la biomasa de ramas largas de varios grados de lignificación, de ramas cortas (dardos y lamburdas, de frutos y de hojas (tiernas y maduras, y que tienen coeficientes de determinación (R2 superiores a 0.972 y valores para el estadístico de Mallow muy próximos al número de variables independientes participantes. Normalmente una variable independiente tiene una participación muy alta en cada modelo. Para las brindillas, dardos y lamburdas, el volumen calculado por las fórmulas de cono y del cono truncado para ramas no podadas y podadas, respectivamente, fue la principal (R2 parciales entre 0.933 y 0.995. En el caso del fruto, la principal variable en el modelo generado es el diámetro polar mínimo en su forma cuadrática (R2 parcial de 0.974. Para los modelos de las hojas tiernas y maduras, la variable que más contribuye es la longitud de la lámina (R2 parciales de 0.936 y 0.962, respectivamente.

  19. Právo na asistovanou reprodukci jako základní lidské právo?

    Czech Academy of Sciences Publication Activity Database

    Doležal, Adam; Doležal, Tomáš

    Bratislava : Wolters Kluwer, 2014 - (Humeník, I.; Szaniszló, I.; Zoláková, Z.), s. 10-26 ISBN 978-80-8168-035-9. [Reprodukčné zdravie ženy v centre záujmu - Právne, bioetické, medicínske a psychosociálne aspekty starostlivosti o ženské zdravie. Košice (SK), 10.04.2014-11.04.2014] R&D Projects: GA ČR GAP408/12/2564 Institutional support: RVO:68378122 Keywords : European Court of Human Rights * access to assisted reproduction * In Vitro Fertilization Subject RIV: AG - Legal Sciences

  20. Právo na informace jako základní lidské právo

    Czech Academy of Sciences Publication Activity Database

    Kolman, Jiří

    Brno : Masarykova univerzita, 2015 - (Večeřa, M.; Stachoňová, M.; Hapla, M.), s. 154-164 ISBN 978-80-210-8001-0. - (Scientia. Řada teoretická. 530). [Weyrův den právní teorie. Brno (CZ), 05.06.2015-] R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : right to information * basic human rights * freedom of information and institutions of the European Union * EU administrative law * democracy * public international law * diplomacy * supranacionalism * intergovernmentalism Subject RIV: AG - Legal Sciences

  1. A VoIP Privacy Mechanism and its Application in VoIP Peering for Voice Service Provider Topology and Identity Hiding

    CERN Document Server

    Shen, Charles

    2008-01-01

    Voice Service Providers (VSPs) participating in VoIP peering frequently want to withhold their identity and related privacy-sensitive information from other parties during the VoIP communication. A number of existing documents on VoIP privacy exist, but most of them focus on end user privacy. By summarizing and extending existing work, we present a unified privacy mechanism for both VoIP users and service providers. We also show a case study on how VSPs can use this mechanism for identity and topology hiding in VoIP peering.

  2. Structural characterization of PrVO3 epitaxial thin films

    CERN Document Server

    Copie, O; Boullay, P; Morales, M; Pautrat, A; David, A; Mercey, B; Pravarthana, D; Infante, I C; Janolin, P -E; Prellier, W

    2014-01-01

    Rare earth perovskite oxides constitute a wide family of materials presenting functional proper- ties strongly coupled to their crystalline structure. Here, we report on the experimental results on epitaxial PrVO3 deposited on SrTiO3 single crystal substrates by pulsed laser deposition. By com- bining advanced structural characterization tools, we have observed that the PVO unrelaxed film structure grown on STO, is characterized by two kinds of oriented domains whose epitaxial relations are: (i) PrVO3[110]o//SrTiO3[001]c and PrVO3[001]o//SrTiO3[100]c, (ii) PrVO3[110]o//SrTiO3[001]c and PrVO3[001]o//SrTiO3[010]c. We have also measured reciprocal space maps. From these results, we have determined that the PVO film epitaxy on STO imposes a lowering of the PVO structure symmetry from orthorhombic (Pbnm) to monoclinic (P21/m). We show, the nominal strain induced by the substrate being constant, that the obtained film structure depends on both growth oxygen and temperature. Thus, by finely controlling the depositio...

  3. 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

  4. Proposal of Secure VoIP System Using Attribute Certificate

    Science.gov (United States)

    Kim, Jin-Mook; Jeong, Young-Ae; Hong, Seong-Sik

    VoIP is a service that changes the analogue audio signal into a digital signal and then transfers the audio information to the users after configuring it as a packet; and it has an advantage of lower price than the existing voice call service and better extensibility. However, VoIP service has a system structure that, compared to the existing PSTN (Public Switched Telephone Network), has poor call quality and is vulnerable in the security aspect. To make up these problems, TLS service was introduced to enhance the security. In practical system, however, since QoS problem occurs, it is necessary to develop the VoIP security system that can satisfy QoS at the same time in the security aspect. In this paper, a user authentication VoIP system that can provide a service according to the security and the user through providing a differential service according to the approach of the users by adding AA server at the step of configuring the existing VoIP session is suggested. It was found that the proposed system of this study provides a quicker QoS than the TLS-added system at a similar level of security. Also, it is able to provide a variety of additional services by the different users.

  5. Thermochromic VO2 on Zinnwaldite Mica by pulsed laser deposition

    International Nuclear Information System (INIS)

    Highlights: • Vanadium dioxide was successfully synthesized by pulsed laser deposition method on mica. • The morphology evolution within the samples is characterized by a change from isolated and less-percolating (0 1 1) VO2 crystallites to a percolating granular configuration. • Without any post annealing, the films exhibit a textured nature with a VO2 (0 1 1) preferred crystallographic orientation and an elevated thermal variation of the electric resistance ratio RS/RM through the SMT at T ≈ 68 °C of the order of 104 and a narrow ∼7 °C hysteresis. - Abstract: VO2 thin films have been deposited by pulsed laser deposition on Zinnwaldite Mica substrates. The crystal structure, chemical composition, morphology were determined and the semiconductor/metal transition (SMT) properties of the deposited films were investigated. Without any post annealing, the films exhibit a textured nature with a VO2 (0 1 1) preferred crystallographic orientation and an elevated thermal variation of the electric resistance ratio RS/RM through the SMT at T ≈ 68 °C of the order of 104 and a narrow ∼7 °C hysteresis. In addition, the growth of the VO2 crystallites seem to be governed likely by a Volmer-Weber or Stranski-Krastanov mechanisms and certainly not a Frank-van Der Merwe process

  6. Electronic structure and insulating gap in epitaxial VO2 polymorphs

    Directory of Open Access Journals (Sweden)

    Shinbuhm Lee

    2015-12-01

    Full Text Available Determining the origin of the insulating gap in the monoclinic V O2(M1 is a long-standing issue. The difficulty of this study arises from the simultaneous occurrence of structural and electronic transitions upon thermal cycling. Here, we compare the electronic structure of the M1 phase with that of single crystalline insulating V O2(A and V O2(B thin films to better understand the insulating phase of VO2. As these A and B phases do not undergo a structural transition upon thermal cycling, we comparatively study the origin of the gap opening in the insulating VO2 phases. By x-ray absorption and optical spectroscopy, we find that the shift of unoccupied t2g orbitals away from the Fermi level is a common feature, which plays an important role for the insulating behavior in VO2 polymorphs. The distinct splitting of the half-filled t2g orbital is observed only in the M1 phase, widening the bandgap up to ∼0.6 eV. Our approach of comparing all three insulating VO2 phases provides insight into a better understanding of the electronic structure and the origin of the insulating gap in VO2.

  7. Electronic structure and insulating gap in epitaxial VO2 polymorphs

    Science.gov (United States)

    Lee, Shinbuhm; Meyer, Tricia L.; Sohn, Changhee; Lee, Donghwa; Nichols, John; Lee, Dongkyu; Seo, Sung S. Ambrose; Freeland, John W.; Noh, Tae Won; Lee, Ho Nyung

    2015-12-01

    Determining the origin of the insulating gap in the monoclinic V O2(M1) is a long-standing issue. The difficulty of this study arises from the simultaneous occurrence of structural and electronic transitions upon thermal cycling. Here, we compare the electronic structure of the M1 phase with that of single crystalline insulating V O2(A) and V O2(B) thin films to better understand the insulating phase of VO2. As these A and B phases do not undergo a structural transition upon thermal cycling, we comparatively study the origin of the gap opening in the insulating VO2 phases. By x-ray absorption and optical spectroscopy, we find that the shift of unoccupied t2g orbitals away from the Fermi level is a common feature, which plays an important role for the insulating behavior in VO2 polymorphs. The distinct splitting of the half-filled t2g orbital is observed only in the M1 phase, widening the bandgap up to 0.6 eV. Our approach of comparing all three insulating VO2 phases provides insight into a better understanding of the electronic structure and the origin of the insulating gap in VO2.

  8. Thermochromic characteristics of Ti-doped VO2 thin film

    Science.gov (United States)

    Lee, Hwasoo; Ko, Kyung Hyun; Choi, Jun Oh

    2014-03-01

    Utilizing metal-to-insulator transition (MIT) properties of V-oxide film, stable VO2 phase is necessary. In sputtering deposition of VO2, simple target preparation and high deposition rate are recommendable. For this, VO2 film was deposited on quartz substrate by RF magnetron sputter system under low working pressure using V2O5 target. Due to the lower sputtering yield of oxygen compared to vanadium, oxygen ion contents is usually deficient from that of target. So, the reduction of V ions was a result of charge compensation with the oxygen ions. Under lower working pressure, deposition rate become higher so that this deficiency is getting larger to cause further reduction to destabilize VO2. Preventing this, titanium oxide co-deposition was suggested to enrich oxygen source. When TiO2 was used, Ti ion has stable +4 charge state so that extra oxygen sputtered prevents V ion reduction below +4 state. But, in case of TiO, Ti ions were oxidized from +2 to +3 and +4 state and V ions with less oxidation potential should be reduced to +3 or so. Pure VO2 film had MIT at 66C and large resistivity ratio of 4 orders of magnitude from 30C to 90C. Under low working pressure, (V2O5 + TiO2) system yield fairly good films, while films with poor or absence of MIT were produced with TiO case.

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

    Scientific Electronic Library Online (English)

    Anirebis, Martnez Romero; Angel, Leyva Galn.

    2014-03-01

    Full Text Available La biomasa es el resultado de la transformacin de la energa solar en energa qumica. El hombre a travs de la historia la ha utilizado no solo para su alimentacin sino tambin para la alimentacin de sus animales. Los avances de la ciencia promovieron el desarrollo agrario basado en la revoluci [...] n verde, la cual solo promueve la produccin 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 produccin y conservacin de la biomasa de cualquier cultivo cobra una importancia trascendente; por que ello contribuye, adems, a la proteccin medioambiental a travs 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 tambin 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 produccin de biomasa en su relacin con el medio ambiente. Finalmente se exponen los resultados preliminares sobre produccin 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.

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

    Directory of Open Access Journals (Sweden)

    Magalis Zabala

    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 agrícolas 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.

  11. Liquidus surface of NaNO3-Na2W2O7-WO3 system

    International Nuclear Information System (INIS)

    State diagrams of the system sodium metavanadate-tungsten (6) oxide, liquidus surface of the system sodium metavanadate-sodium ditungstate-tungsten (6) oxide were studied. In the first system two new phases 3NaVO3WO3 and NaNO32WO3 are formed. Diagram of primary crystallization surface of the second system is plotted. Compositions and melting points of ternary nonvariant points are determined

  12. Implementasi Server VoIP Berbasis SIP Pada LAN Nirkabel

    Directory of Open Access Journals (Sweden)

    Mohammad Shoffa Al Arofat

    2015-03-01

    Full Text Available Voice over Internet Protocol (VoIP merupakan teknologi yang memungkinkan percakapan suara jarak jauh melalui protokol internet. Dalam telekomunikasi, diperlukan teknologi pensinyalan yang berguna untuk membangun, mengawasi, dan melepas hubungan antara dua titik. Salah satu teknologi pensinyalan yang banyak digunakan untuk VoIP adalah Session Initiation Protocol, dengan implementasinya yang berupa perangkat lunak Open SIP Server. Selain pensinyalan, ada beberapa parameter yang perlu diperhatikan dalam implementasi VoIP, yaitu Mean Opinion Score (MOS, network impairment, dan bandwidth. Pengujian dilakukan terhadap enam codec, yaitu G.722, PCMA, PCMU, Speex, GSM, dan BV16. Berdasarkan hasil analisis dapat diambil kesimpulan bahwa codec yang menggunakan bandwidth paling rendah adalah Speex (27,12 kbps; Rata-rata delay yang dihasilkan oleh sipdroid lebih baik daripada jitsi.

  13. Room-temperature magnetism in LaVO3/SrVO3 superlattices by geometrically confined doping

    Science.gov (United States)

    Lders, U.; Sheets, W. C.; David, A.; Prellier, W.; Frsard, R.

    2009-12-01

    Based on the Hubbard model of strongly correlated systems, a reduction in the bandwidth of the electrons can yield a substantial change in the properties of the material. One method to modify the bandwidth is geometrically confined doping, i.e., the introduction of a (thin) dopant layer in a material. In this Rapid Communication, the magnetic properties of LaVO3/SrVO3 superlattices, in which the geometrically confined doping is produced by a one monolayer thick SrVO3 film, are presented. In contrast to the solid solution La1-xSrxVO3 , such superlattices have a finite magnetization up to room temperature. Furthermore, the total magnetization of the superlattice depends on the thickness of the LaVO3 layer, indicating an indirect coupling of the magnetization that emerges at adjacent dopant layers. Our results show that geometrically confined doping, like it can be achieved in superlattices, reveals a way to induce otherwise inaccessible phases possibly even with a large temperature scale.

  14. 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; Jos Mara Rey B

    2009-01-01

    El uso de los ecosistemas forestales como sumideros y reservorios de carbono es cada da ms aceptado. An as, la informacin fidedigna sobre su crecimiento en biomasa y la capacidad de captura y de almacenamiento de CO2 es insuficiente para proponer formas de compensacin a los propietarios de bosques. El objetivo de este trabajo fue construir modelos para estimar la biomasa del rbol en plantaciones de Hieronyma alchorneoides, Vochysia guatemalensis y para un grupo de 35 especies en bosque...

  15. Preparation and crystal structure of a new bismuth vanadate, Bi{sub 3.33}(VO{sub 4}){sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kumada, N., E-mail: kumada@yamanashi.ac.jp [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511 Japan (Japan); Takei, T.; Haramoto, R.; Yonesaki, Y.; Dong, Q.; Kinomura, N. [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511 Japan (Japan); Nishimoto, S.; Kameshima, Y.; Miyake, M. [Department of Material and Energy Science, Graduate School of Environmental Science, Okayama University, Tsusima-Naka 3-3-1, Okayama 700-8530 Japan (Japan)

    2011-06-15

    Graphical abstract: Crystal structure of Bi{sub 3.33}(VO{sub 4}){sub 2}O{sub 2}. Solid lines indicate the unit cell. Highlights: {yields} We can prepare a new bismuth vanadate, Bi{sub 3.33}(VO{sub 4}){sub 2}O{sub 2} by hydrothermal reaction using a hydrated sodium bismuthate. {yields} We clarify that the crystal structure is composed by four bismuth atoms with the coordination number of 6 or 8 and two VO{sub 4} tetrahedra. {yields} This compound exhibited photocatalytic behavior for decomposition of phenol under visible light irradiation. -- Abstract: Single crystals of a new bismuth vanadate, Bi{sub 3.33}(VO{sub 4}){sub 2}O{sub 2} was prepared by hydrothermal reaction using a hydrated sodium bismuthate, NaBiO{sub 3}.nH{sub 2}O 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{sup -bar} (no. 2) with a = 7.114(1), b = 7.844(2), c = 9.372(2) A, {alpha} = 106.090(7), {beta} = 94.468(7) and {gamma} = 112.506(8){sup 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 VO{sub 4} 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 BiVO{sub 4}.

  16. Lattice effects in HoVo3 single crystal

    International Nuclear Information System (INIS)

    We report the study of lattice effects in the Mott insulator HoVO3 performed by means of linear thermal expansion on a single crystal in the temperature range 10-290 K. The holmium orthovanadate HoVO3 reveals gradual orbital ordering (OO) below T OO=200 K and orders antiferromagnetically at T N=113 K. A first-order structural phase transition takes place at T S∼38 K, which is probably accompanied by change of the OO type and hence the type of antiferromagnetic spin ordering

  17. RegTAP - a New API to the VO Registry

    Science.gov (United States)

    Demleitner, M.

    2015-09-01

    The Virtual Observatory (VO) Registry is a comprehensive directory of astronomical services maintained collaboratively by major data centers across the globe. Until now, the API to the Registry as used by clients and users relied on several outdated standards, and has interoperability issues with more advanced queries. With RegTAP, there is now a relational schema exposed via the VO's Table Access Protocol as implemented by many clients, and several compliant services already exist. While many users will just use UIs operating RegTAP , both advanced users and client authors will want to directly operate the API. This paper provides an overview of RegTAP.

  18. Infrared-sensitive electrochromic device based on VO2

    Science.gov (United States)

    Nakano, M.; Shibuya, K.; Ogawa, N.; Hatano, T.; Kawasaki, M.; Iwasa, Y.; Tokura, Y.

    2013-10-01

    The field-effect transistor (FET) provides an electrical switching function of current flowing through a channel surface by external voltage. Here, we report on a field-effect device that enables electrical switching of optical transmittance as well as conventional electrical current. We investigated optical properties of vanadium dioxide (VO2) thin film under the presence of electric field generated at the interface between VO2 and ionic liquid in a FET geometry, and found that the device exhibits clear electrochromic effect with large ON/OFF contrast only in the infrared region, potentially beneficial for energy-saving smart window applications as a voltage-tunable transparent heat-cutting filter.

  19. Update of the China-VO AstroCloud

    CERN Document Server

    Cui, Chenzhou; Xiao, Jian; He, Boliang; Li, Changhua; Fan, Dongwei; Wang, Chuanjun; Hong, Zhi; Li, Shanshan; Mi, Linying; Wan, Wanghui; Cao, Zihuang; Wang, Jiawei; Yin, Shucheng; Fan, Yufeng; Wang, Jianguo; Yang, Sisi; Ling, Yin; Zhang, Hailong; Chen, Junyi; Liu, Liang; Chen, Xiao

    2016-01-01

    As the cyber-infrastructure for Astronomical research from Chinese Virtual Observatory (China-VO) project, AstroCloud has been archived solid progresses during the last one year. Proposal management system and data access system are re-designed. Several new sub-systems are developed, including China-VO PaperData, AstroCloud Statics and Public channel. More data sets and application environments are integrated into the platform. LAMOST DR1, the largest astronomical spectrum archive was released to the public using the platform. The latest progresses will be introduced.

  20. Phase transformation of VO2 nanoparticles assisted by microwave heating.

    Science.gov (United States)

    Phoempoon, Phatcharee; Sikong, Lek

    2014-01-01

    The microwave assisted synthesis nowadays attracts a great deal of attention. Monoclinic phase VO2 (M) was prepared from NH4VO3 and H2C2O4 · 2H2O by a rapid microwave assisted technique. The synthesis parameters, microwave irradiation time, microwave power, and calcinations temperature were systematically varied and their influences on the structure and morphology were evaluated. The microwave power level has been carried out in range 180-600 W. TEM analysis demonstrated nanosized samples. The structural and morphological properties were measured using XRD, TEM, and thermal analyses. The variations of vanadium phase led to thermochromic properties. PMID:24688438

  1. Lightweight security mechanism for PSTN-VoIP cooperation

    CERN Document Server

    Mazurczyk, W; Mazurczyk, Wojciech; Kotulski, Zbigniew

    2006-01-01

    In this paper we describe a new, lightweight security mechanism for PSTN-VoIP cooperation that is based on two information hiding techniques: digital watermarking and steganography. Proposed scheme is especially suitable for PSTN-IP-PSTN (toll-by-passing) scenario which nowadays is very popular application of IP Telephony systems. With the use of this mechanism we authenticate end-to-end transmitted voice between PSTN users. Additionally we improve IP part traffic security (both media stream and VoIP signalling messages). Exemplary scenario is presented for SIP signalling protocol along with SIP-T extension and H.248/Megaco protocol.

  2. Biomasa – obnovljiva sirovina za organske kemikalije (“Bijela kemija”)

    OpenAIRE

    V. P. Kukhar

    2009-01-01

    Ograničeni prirodni resursi prisiljavaju nas da se okrenemo obnovljivim izvorima, starim i novim, koji mogu osigurati održivost ljudske zajednice i zadovoljiti naše potrebe za energijom i materijalima. Biljni svijet ima ogroman potencijal kao sirovina za proizvodnju organskog materijala. Ovaj pregled posvećen je upotrebi biomase za proizvodnju nekih osnovnih organskih kemikalija te glavnim smjerovima razvitka tehnologije za preradu biomase. To su uglavnom procesi koji pretvaraju celulozu i ug...

  3. Bu? zmenou, ktor chce vo svete vidie?

    Directory of Open Access Journals (Sweden)

    Peter Ma?o

    2011-12-01

    Full Text Available Reklama primla tchto ?ud nah?a? sa za autami a atami, ktor nepotrebuj. Genercie pracuj v zamestnaniach, ktor neznaj, len aby si mohli kpi? to, ?o v skuto?nosti nepotrebuj. A tak sme sa ocitli v situcii, ke? nevlastnme veci, ale veci vlastnia ns, (Klub bitkrov, 1999. Od svitu ?udstva je kad spolo?nos? charakteristick aplikovanm jedine?nej stratgie preitia vzh?adom na okolit prostredie a okolit spolo?nosti. Tieto stratgie sa lia predovetkm svojm dosahom na ivotn prostredie a na ?ud, ktor v ?om ij. Hlavne za obdobie poslednch 10 000 rokov, teda pribline od db prvej domestikcie rastln a zvierat, sa ve?a stratgi uberalo nie ve?mi priaznivm smerom, ?o dokazuj nelichotiv tatistiky ?udskch obet a vy?erpanch ekosystmov. ia?, tento trend sa neustle stup?uje a jeho najv?m vyvrcholenm je prve s?asnos?. Ak sa bavme o nejakom civiliza?nom pokroku a neustlom rozvoji, toto je potom jeho temn strnka, ktor je ale ?asto ignorovan a prehliadan. ?o teda urobi? pre to, aby bol vvoj udrate?n?

  4. Urchin-like m-LaVO{sub 4} and m-LaVO{sub 4}/Ag microspheres: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Limiao, E-mail: chenlimiao@csu.edu.cn [School of Minerals Processing and Bioengineering, Central South University, Changsha 410083 (China); College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Wu, Min; Wang, Dan; Zhou, Le; Yu, Na; Zhang, Peisen; Huang, Jianhan [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Liu, Xiaohe, E-mail: liuxh@csu.edu.cn [School of Minerals Processing and Bioengineering, Central South University, Changsha 410083 (China); Qiu, Guanzhou [School of Minerals Processing and Bioengineering, Central South University, Changsha 410083 (China)

    2014-12-15

    The semiconductor nanostructures decorated with noble metals have attracted increasing attention due to their interesting physical and chemical properties. In this work, urchin-like monoclinic (m-) LaVO{sub 4} microspheres were prepared by a hydrothermal method and used as a template to fabricate Ag nanoparticle-decorated m-LaVO{sub 4} composites. The morphology and structure were characterized by transmission electron microscope, high-resolution transmission electron microscope, scanning electron microscope, and energy-dispersive X-ray. It was found that Ag nanoparticles with narrow size distribution were uniformly loaded on urchin-like m-LaVO{sub 4} microspheres, and the resulted composite microspheres showed distinct surface plasmon absorption band compared to pure m-LaVO{sub 4} microspheres. Photocatalytic activities of as-prepared samples were examined by studying the degradation of methyl orange solutions under visible-light irradiation (> 400 nm). Results clearly showed that urchin-like m-LaVO{sub 4}/Ag microspheres possess much higher photocatalytic activity than pure m-LaVO{sub 4} microspheres and P25. - Highlights: m-LaVO{sub 4}/Ag composites microspheres were fabricated by a hydrothermal method. m-LaVO{sub 4} microspheres show higher photocatalytic activity than m-LaVO{sub 4} microspheres. m-LaVO{sub 4}/Ag microspheres exhibit a good stability.

  5. 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...

  6. Oxygen pressure dependent VO2 crystal film preparation and the interfacial epitaxial growth study

    International Nuclear Information System (INIS)

    High quality VO2 crystal films have been prepared on sapphire substrates by pulsed laser deposition method and the effects of oxygen pressure on the crystal phase structure are investigated. Results indicate that the phases and microstructures of VO2 films are strongly sensitive to oxygen pressure. High oxygen pressure tends to form coarse B-VO2 nanocrystals while low pressure favors a flat M1-VO2 film epitaxial growth. X-ray diffraction ?-scan patterns confirm the [020] epitaxial growth orientation of the M1-VO2 film and the in-plane lattice epitaxial relationship at the interface is also examined. Raman spectra indicate that M1-VO2 phase has much stronger Raman scattering modes than B-VO2, and the clear phonon modes further confirm the idea stoichiometry of VO2 crystal film. Infrared transmittance spectra as the function of temperature are recorded and the results show that M1-VO2 crystal films undergo a distinct infrared transmittance variation across metal insulator transition boundary, while B-VO2 exhibits negligible thermochromic switching properties in the temperature range concerned. The pronounced phase transition behavior of the M1-VO2 crystal film makes it a promising candidate for optical filter/switch and smart window applications in the future. - Highlights: ? High quality VO2 films with different phase structures were obtained by PLD method. ? High oxygen pressure tends to form B-VO2 while low pressure favors M1-VO2 film. ? ?-scan XRD confirms the [020] epitaxial growth orientation of the M1-VO2 film. ? The epitaxial relationship is explained based on domain matching theory. ? M1-VO2 film shows excellent optical property in infrared range.

  7. Evidence of cardiac functional reserve upon exhaustion during incremental exercise to determine VO2max

    OpenAIRE

    Elliott, Adrian; Skowno, Justin; Prabhu, Mahesh; Noakes, Timothy; Ansley, Les

    2015-01-01

    Background - There remains considerable debate regarding the limiting factor(s) for maximal oxygen uptake (VO2max). Previous studies have shown that the central circulation may be the primary limiting factor for VO2max and that cardiac work increases beyond VO2max. Aim - We sought to evaluate whether the work of the heart limits VO2max during upright incremental cycle exercise to exhaustion. Methods - Eight trained men completed two incremental exercise trials, each terminating with e...

  8. EFECTO DEL VERMIABONO EN CRECIMIENTO Y ACUMULACIÓN DE BIOMASA EN Aeschynomene americana L. EN BANCOS DE MINERÍA A CIELO ABIERTO

    Directory of Open Access Journals (Sweden)

    Rosa de Lourdes Romo Campos

    2009-01-01

    instauraron parcelas de 1 m2 a las que se les adicionó 1 kg m-2 de vermiabono (compost de lombriz Eisenia foetida y se compararon con un testigo al cual no se le aplicó vermiabono. Después de un ciclo de cultivo se observó que no existieron diferencias en la sobrevivencia de las plantas (10 y 16%, pero sí en la tasa de crecimiento, debido a que las plantas tratadas con vermiabono lograron alturas ocho veces mayores que el tratamiento testigo. Esta diferencia también se observó en la acumulación de biomasa al final del ciclo de vida de la planta (120 días, puesto que las plantas tratadas acumularon 21.7 g m-2 de materia seca; de los cuales 7 g m-2 se destinaron a la producción del fruto, en contraste con las plantas del tratamiento testigo que acumularon 1.5 g m-2 de biomasa y sólo 0.2 g m-2 se asignaron a los frutos, por lo que estas plantas no produjeron semillas. Las plantas tratadas con vermiabono formaron menos raíz respecto a la biomasa total en comparación con el tratamiento testigo, por lo cual se concluye que la aplicación de compost de lombriz promueve el desarrollo de A. americana hasta formar semillas.

  9. Variaciones de abundancia y biomasa del zooplancton en un embalse tropical oligo-mesotrfico 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 est determinada principalmente por la velocidad y el contenido del agua, pero se sabe relativamente poco sobre los embalses tropicales. Se estudi la distribucin 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 domin la comunidad, mientras que los rotferos fueron los ms diversos, con 10 especies. La abundancia del zooplancton vari de 31 a 101ind/l en E1, 36 a 84ind/l en E2, y, de 30 a 250ind/L en el E3. La biomasa vari 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.

  10. 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].

  11. Multi-VO support in IHEP's distributed computing environment

    Science.gov (United States)

    Yan, T.; Suo, B.; Zhao, X. H.; Zhang, X. M.; Ma, Z. T.; Yan, X. F.; Lin, T.; Deng, Z. Y.; Li, W. D.; Belov, S.; Pelevanyuk, I.; Zhemchugov, A.; Cai, H.

    2015-12-01

    Inspired by the success of BESDIRAC, the distributed computing environment based on DIRAC for BESIII experiment, several other experiments operated by Institute of High Energy Physics (IHEP), such as Circular Electron Positron Collider (CEPC), Jiangmen Underground Neutrino Observatory (JUNO), Large High Altitude Air Shower Observatory (LHAASO) and Hard X-ray Modulation Telescope (HXMT) etc, are willing to use DIRAC to integrate the geographically distributed computing resources available by their collaborations. In order to minimize manpower and hardware cost, we extended the BESDIRAC platform to support multi-VO scenario, instead of setting up a self-contained distributed computing environment for each VO. This makes DIRAC as a service for the community of those experiments. To support multi-VO, the system architecture of BESDIRAC is adjusted for scalability. The VOMS and DIRAC servers are reconfigured to manage users and groups belong to several VOs. A lightweight storage resource manager StoRM is employed as the central SE to integrate local and grid data. A frontend system is designed for user's massive job splitting, submission and management, with plugins to support new VOs. A monitoring and accounting system is also considered to easy the system administration and VO related resources usage accounting.

  12. Structure and magnetism of epitaxial PrVO3 films.

    Science.gov (United States)

    Copie, O; Rotella, H; Boullay, P; Morales, M; Pautrat, A; Janolin, P-E; Infante, I C; Pravathana, D; Lders, U; Prellier, W

    2013-12-11

    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 80K. We discuss these properties in view of the thin-film structure. PMID:24214665

  13. 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.

  14. Upcoming Features of SPLAT-VO in Astroinformatics

    Czech Academy of Sciences Publication Activity Database

    Šaloun, P.; Andrešič, D.; Škoda, Petr; Zelinka, I.

    Vol. 210. Cham : Springer, 2013, s. 475-486 ISBN 978-3-319-00541-6. ISSN 2194-5357. [Nostradamus 2013. Ostrava (CZ), 03.06.2013-05.06.2013] R&D Projects: GA ČR GA13-08195S Institutional support: RVO:67985815 Keywords : SPLAT-VO * spectrum analysis * SAMP Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  15. Potentiometric parameters of a PVC-NaV6O15 - graphite electrode

    International Nuclear Information System (INIS)

    The behavior of the film electrodes on the base of polyvinyl chloride (PVC), modified by bronze of the NaV6O15 (Na0.33V2O5) composition is studied. The electrodes are selective to the pentavalent vanadium ions in acid and neutral media. It is shown, that the sensitive area of concentrations is within the frames of 10-2-10-5 M. The potential dependence on concentration is subjected to the Hernst equation with the 59.4±0.8 mV/pc angular coefficient corresponding to the VO2+ → VO2+ single electron transition by ph 1.5-2.0 (cation function). Dependence of the potential on concentration, corresponding to the VO3- → VO2+ transition (anion function), the angular coefficient -58.0±0.7 mV/pc, is observed by ph 5.0-6.0

  16. Lokace volajícího při tísňových hovorech VoIP

    OpenAIRE

    Mrník, Martin

    2013-01-01

    Táto diplomová práca sa zaoberá problematikou určovania polohy volajúceho na tiesňovú linku so zameraním na hovory prenášane VoIP protokolom. Obsahuje všeobecne popísané hlavné aktívne a pasívne metódy, ktoré možno pre geolokáciu použiť, a vysvetľuje ich funkciu. V práci je analyzované zastúpenie jednotlivých VoIP klientov a popísaný spôsob fungovania programu Skype. Ťažiskovou témou práce je vytvorenie aplikácie na geolokáciu volajúceho pomocou analýzy VoIP prenosu. Aplikácia vyčítava IP adr...

  17. 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

  18. Role of mechanochemical milling in FeVO4 synthesis

    International Nuclear Information System (INIS)

    Single phase, a FeVO4 triclinic crystalline structure was successfully synthesized by annealing the mechanochemically milled xV2O5·(1−x)α-Fe2O3 composites (x=0.5) at 550 °C for 1 h. X-ray powder diffraction (XRD), simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC–TGA), Mössbauer spectroscopy, scanning electron microscopy (SEM), and optical diffuse reflectance spectroscopy were combined for a detailed study of the assisting role of the mechanochemical milling process. Mechanochemical milling homogeneously mixed the starting materials of α-Fe2O3 and V2O5 and substantially decreased their average grain sizes. The Mössbauer spectroscopy studies showed that the spectrum of the mechanochemically milled composites consisted of three sextets and one doublet, indicating the occurrence of V5+–Fe3+ ion substitutions in the corresponding α-Fe2O3 and V2O5 lattices, respectively. The partially V5+-substituted α-Fe2O3 phase and Fe3+-substituted V2O5 could be the important intermediate phases in the production of FeVO4 single phase. The synthesized FeVO4 phase had a slightly distorted nature with an unequal ratio in Fe3+ population in three inequivalent sites. Simultaneous DSC–TGA studies indicated that the synthesized FeVO4 is thermally stable up to 600 °C. SEM images of the formed FeVO4 confirmed the wide particles size distribution range composed of nano-grains. Optical diffuse reflectance spectroscopy studies showed that the synthesized FeVO4 phase had semiconductor properties, with the band gap energy of ~2.44 eV. - Highlights: • X-ray powder diffraction, simultaneous DSC/TGA, Mössbauer spectroscopy, SEM and optical diffuse reflectance spectroscopy. • Mechanochemical synthesis of single-phase FeVO4. • Semiconductor properties and determination of the band gap energy

  19. Microstructure of orientation controlled VO2 thin films via ZnO buffer

    International Nuclear Information System (INIS)

    B-axis preferential oriented VO2 thin films were prepared on glass substrates via ZnO buffers by pulsed laser deposition. In order to explore the relationship between the VO2 and ZnO layers, cross-sectional images of the orientation-controlled VO2 thin films were examined using a transmission electron microscope (TEM). As revealed by the TEM images, for the VO2 thin films deposited on a relatively thick ZnO buffer (∼ 70 nm), an interface layer was formed between the VO2 and ZnO layers. The interface layer was identified as V3O5 based on X-ray photoelectron spectra (XPS) and high resolution TEM images. For the VO2 thin films deposited on a 5-nm thick ZnO buffer, only a b-axis oriented VO2 layer was observed. The b-axis oriented VO2 layer displayed a columnar structure, and the layer thickness was occupied by one grain. However, TEM images of the thicker VO2 thin films (∼ 90 nm) deposited on 5-nm ZnO buffer revealed a VO2 (111) facet on the grain and amorphous residues of VO2. These results indicated that the grains of VO2 grew from the interface with the ZnO buffer, and the grain growth was slower than the speed of deposition. - Highlights: ► B-axis oriented VO2 thin films were prepared on glass on ZnO buffer layers. ► Transmission electron microscopy confirms the formation of an interface layer. ► X-ray photoelectron spectroscopy data reveal a V3O5 interface layer. ► VO2 (111) facet on grains and amorphous residues of VO2 were observed. ► The grain growth was slower than the rate of deposition

  20. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anamika [Department of Life Sciences, University of Mumbai, Santacruz (E), Mumbai 400 098 (India); Dutta, Dimple P., E-mail: dimpled@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ballal, A. [Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Fulekar, M.H. [School of Environment and Sustainable Development, Central University of Gujarat, Gandhinagar 382 030, Gujarat (India)

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  1. Solutions to performance problems in VoIP over a 802.11 wireless LAN

    OpenAIRE

    Wang, W; Liew, SC; Li, VOK

    2005-01-01

    Voice over Internet Protocol (VoIP) over a wireless local area network (WLAN) is poised to become an important Internet application. However, two major technical problems that stand in the way are: 1) low VoIP capacity in WLAN and 2) unacceptable VoIP performance in the presence of coexisting traffic from other applications. With each VoIP stream typically requiring less than 10 kb/s, an 802.11b WLAN operated at 11 Mb/ s could in principle support more than 500 VoIP sessions. In actuality, no...

  2. An Analysis for Anonymity and Unlinkability for a VoIP Conversation

    OpenAIRE

    Zhang, Ge

    2010-01-01

    With the growth of its popularity, VoIP is increasingly popular nowadays. Similarly to other Internet applications, VoIP users may desire to be unlinkable with their participated VoIP session records for privacy issues. In this paper, we explore the Items of Interests (IOIs) from anonymisation aspects based on a simplified VoIP model and analyse the potential links between them. We address possible methods to break the links. Finally, we also discuss requirements for a VoIP anonymisation Serv...

  3. 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…

  4. A VoIP Privacy Mechanism and its Application in VoIP Peering for Voice Service Provider Topology and Identity Hiding

    OpenAIRE

    Shen, Charles; Schulzrinne, Henning

    2008-01-01

    Voice Service Providers (VSPs) participating in VoIP peering frequently want to withhold their identity and related privacy-sensitive information from other parties during the VoIP communication. A number of existing documents on VoIP privacy exist, but most of them focus on end user privacy. By summarizing and extending existing work, we present a unified privacy mechanism for both VoIP users and service providers. We also show a case study on how VSPs can use this mechanism for identity and...

  5. Synthesis of novel photocatalytic RGO-InVO4 nanocomposites with visible light photoactivity

    International Nuclear Information System (INIS)

    Graphical abstract: A facile method for preparation of reduced graphene oxide (RGO) sheets supported indium vanadate (InVO4) photocatalysts is reported. The visible light response and adsorption ability of RGO-InVO4 nanocomposites is greatly improved, which can effectively remove methyl orange and Cr (VI) from water. - Highlights: Supramolecular photocatalyst of RGO-InVO4 was achieved. Reduction of GO and preparation of RGO-InVO4 was simultaneous. The prepared RGO-InVO4 shows high photocatalytic activity and adsorption capacity under visible light. In situ growth of uniform InVO4 particles on RGO sheets is facile and efficient - Abstract: In this study, we report a facile method for preparation of reduced graphene oxide (RGO) sheets supported indium vanadate (InVO4) photocatalysts. A wide range of characterization techniques, such as Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, Thermogravimetric analysis and Transmission electron microscopy were applied to characterize the obtained composites. The results indicated that the composites consist of uniformly dispersed InVO4 nanocrystals on RGO sheets. Visible light responses of RGO-InVO4 nanocomposites are greatly improved as compared with the bulk InVO4. The as-prepared RGO-InVO4 nanocomposites can effectively remove methyl orange and Cr (VI) from water under visible light irradiation, which can be used as novel photocatalysts for environmental protection

  6. Synthesis of novel photocatalytic RGO-InVO{sub 4} nanocomposites with visible light photoactivity

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Jianfeng; Li, Xianfu [Department of Materials Science, Fudan University, Shanghai, 200433 (China); Huang, Weishi; Li, Na [Center of Special Materials and Technology, Fudan University, Shanghai, 200433 (China); Ye, Mingxin, E-mail: mxye@fudan.edu.cn [Department of Materials Science, Fudan University, Shanghai, 200433 (China); Center of Special Materials and Technology, Fudan University, Shanghai, 200433 (China)

    2013-09-01

    Graphical abstract: A facile method for preparation of reduced graphene oxide (RGO) sheets supported indium vanadate (InVO{sub 4}) photocatalysts is reported. The visible light response and adsorption ability of RGO-InVO{sub 4} nanocomposites is greatly improved, which can effectively remove methyl orange and Cr (VI) from water. - Highlights: Supramolecular photocatalyst of RGO-InVO{sub 4} was achieved. Reduction of GO and preparation of RGO-InVO{sub 4} was simultaneous. The prepared RGO-InVO{sub 4} shows high photocatalytic activity and adsorption capacity under visible light. In situ growth of uniform InVO{sub 4} particles on RGO sheets is facile and efficient - Abstract: In this study, we report a facile method for preparation of reduced graphene oxide (RGO) sheets supported indium vanadate (InVO{sub 4}) photocatalysts. A wide range of characterization techniques, such as Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, Thermogravimetric analysis and Transmission electron microscopy were applied to characterize the obtained composites. The results indicated that the composites consist of uniformly dispersed InVO{sub 4} nanocrystals on RGO sheets. Visible light responses of RGO-InVO{sub 4} nanocomposites are greatly improved as compared with the bulk InVO{sub 4}. The as-prepared RGO-InVO{sub 4} nanocomposites can effectively remove methyl orange and Cr (VI) from water under visible light irradiation, which can be used as novel photocatalysts for environmental protection.

  7. 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

    Directory of Open Access Journals (Sweden)

    Jeeser Alves de Almeida

    2010-02-01

    Full Text Available O objetivo deste estudo foi analisar a validade da equação proposta por Cureton et al. (1995 "VO2peak = -8.41 (MRW + 0.34 (MRW2 + 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 específica 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.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 predictive 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.

  8. Improving the Accuracy of Predicting Maximal Oxygen Consumption (VO2pk)

    Science.gov (United States)

    Downs, Meghan E.; Lee, Stuart M. C.; Ploutz-Snyder, Lori; Feiveson, Alan

    2016-01-01

    Maximal oxygen (VO2pk) is the maximum amount of oxygen that the body can use during intense exercise and is used for benchmarking endurance exercise capacity. The most accurate method to determineVO2pk requires continuous measurements of ventilation and gas exchange during an exercise test to maximal effort, which necessitates expensive equipment, a trained staff, and time to set-up the equipment. For astronauts, accurate VO2pk measures are important to assess mission critical task performance capabilities and to prescribe exercise intensities to optimize performance. Currently, astronauts perform submaximal exercise tests during flight to predict VO2pk; however, while submaximal VO2pk prediction equations provide reliable estimates of mean VO2pk for populations, they can be unacceptably inaccurate for a given individual. The error in current predictions and logistical limitations of measuring VO2pk, particularly during spaceflight, highlights the need for improved estimation methods.

  9. Improving the Accuracy of Predicting Maximal Oxygen Consumption (VO2peak)

    Science.gov (United States)

    Downs, Meghan E.; Lee, Stuart M. C.; Ploutz-Snyder, Lori; Feiveson, Alan

    2016-01-01

    Maximal oxygen (VO2pk) is the maximum amount of oxygen that the body can use during intense exercise and is used for benchmarking endurance exercise capacity. The most accurate method to determineVO2pk requires continuous measurements of ventilation and gas exchange during an exercise test to maximal effort, which necessitates expensive equipment, a trained staff, and time to set-up the equipment. For astronauts, accurate VO2pk measures are important to assess mission critical task performance capabilities and to prescribe exercise intensities to optimize performance. Currently, astronauts perform submaximal exercise tests during flight to predict VO2pk; however, while submaximal VO2pk prediction equations provide reliable estimates of mean VO2pk for populations, they can be unacceptably inaccurate for a given individual. The error in current predictions and logistical limitations of measuring VO2pk, particularly during spaceflight, highlights the need for improved estimation methods.

  10. Productividad y biomasa fitoperifítica en los Lagos Tarapoto y Yahuarcaca, Amazonas, Colombia Productividad y biomasa fitoperifítica en los lagos Yahuarcaca y Tarapoto (Amazonas - Colombia

    Directory of Open Access Journals (Sweden)

    Duque Escobar Santiago R.

    2000-06-01

    Full Text Available In the littoral zone, near of the matrix the macrophytes, main for Paspalum spp the lake Yahuarcaca and Tarapoto; the floodplain of the Amazon River-Colombia, through were designed system of artificial substratum, using slips and rods we quantify the productivity primary phytoperiphyton for clorophyl a, through method espectrophotometric and the biomass for ash free dry weight; in three periods hidrology low water, filling water and high water; for two, four and eigh day the colonization; four deep levels and radial position the substratum. The factors that has mayor effect over the primary productivity and the biomass phytoperiphytic are the hidrobiology periods, the colonization of the substratum and deep. The productivity and biomass from the lake is reationship with the mineralization of the water, with the tramsportation of nutrients of afluents, macrophytes, the flood forest, decomposition and the recirculation of nutrients in the water column.En la zona litorial, cerca de la matriz de macrófitas conformadas principalmente por Paspalum spp de los lagos Yahuarcaca y Tarapoto, del plano de inundación del Río Amazonas-Colombia, mediante el diseño de un sistema de substratos artificiales, utilizando láminas portaobjetos y tubos de vidrio, se cuantificó la productividad primaria fitoperifítica por clorofila a, mediante el método espectrofotométrico y la biomasa por peso seco libre de cenizas (PSLC, en tres períodos hidrológicos, aguas bajas, ascenso y altas o desborde; a los 2, 4 y 8 días de colonización; cuatro niveles de profundidad (cada 10 cm y diferente ubicación radial de los substratos. Los factores que tienen mayor efecto sobre la productividad y biomasa fitoperifítica son los períodos hidrológicos, los días de colonización de los substratos y la profundidad. La productividad y biomsa fitoperifítica de los lagos está relacionada con la mineralización de las aguas, el transporte de nutrientes de los afluentes, los macrófitos, el bosque inundable, la descomposición de la materia orgánica y la recirculación de nutrientes en la columna de agua.

  11. 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 VO2Mx velocity (VVO2Mx and the variables VO2Mx, VVO2Mx, 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 relao do tempo limite (Tlim na velocidade do VO2Mx (VVO2Mx com as variveis VO2Mx, VVO2Mx, economia de corrida (EC, limiar ventilatrio (LV, fora isotnica (determinada pelo teste de 9-10 RM, velocidade no teste mximo de corrida anaerbica (VMART, impulso vertical e percentual de gordura (%G . A amostra foi composta por 18 voluntrios do sexo masculino, com idade entre 18 e 45 anos, no atletas, regularmente ativos. O estudo foi realizado em cinco visitas, em dias no consecutivos e aproximadamente no mesmo horrio, compostas de: visita 1 - assinatura do termo de consentimento, anamnese, avaliao antropomtrica, teste de potncia aerbia e familiarizao ao teste de Tlim; visita 2 - teste de EC e teste de Tlim; visita 3 - familiarizao ao teste de VMART; visita 4 - familiarizao aos testes de impulso vertical e 9-10 RM e teste de VMART; visita 5 - testes de impulso vertical e 9-10 RM. Foram observadas correlaes baixas (r = 0,220 a - 0,359 e no significativas (p = 0,281 a 0,935 entre Tlim e as diversas variveis selecionadas, o que caracteriza uma baixa qualidade preditiva para o TLim na amostra estudada. Neste sentido e tendo em vista a considervel variabilidade inter-indivduos do TLim, no foi encontrada uma varivel que pudesse prediz-lo satisfatoriamente.

  12. 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

  13. Synergy Between Archives, VO, and the Grid at ESAC

    Science.gov (United States)

    Arviset, C.; Alvarez, R.; Gabriel, C.; Osuna, P.; Ott, S.

    2011-07-01

    Over the years, in support to the Science Operations Centers at ESAC, we have set up two Grid infrastructures. These have been built: 1) to facilitate daily research for scientists at ESAC, 2) to provide high computing capabilities for project data processing pipelines (e.g., Herschel), 3) to support science operations activities (e.g., calibration monitoring). Furthermore, closer collaboration between the science archives, the Virtual Observatory (VO) and data processing activities has led to an other Grid use case: the Remote Interface to XMM-Newton SAS Analysis (RISA). This web service-based system allows users to launch SAS tasks transparently to the GRID, save results on http-based storage and visualize them through VO tools. This paper presents real and operational use cases of Grid usages in these contexts

  14. 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 ΔR/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

  15. Bandwidth-Conserving Multicast VoIP Teleconference System

    Directory of Open Access Journals (Sweden)

    Teck-Kuen Chua

    2008-07-01

    Full Text Available Teleconferencing is an essential feature in any business telephone system. A teleconference allows associates to engage in a group discussion by conducting a virtual meeting while remaining at geographically dispersed locations. Teleconferencing increases productivity while reducing travel costs and saving travel time. In a VoIP telephone system, we face the significant challenge of providing a teleconference feature that can support a large-scale teleconference without using excessive bandwidth. This paper presents a new, bandwidth-efficient way of implementing a real-time VoIP teleconference system. This new method provides all of the features that existing teleconference systems provide, but this new approach consumes considerably less data bandwidth than existing systems require. The new system allows a network with a given capacity to accommodate almost double the number of conference participants that an existing system would allow.

  16. Gate-tunable gigantic lattice deformation in VO2

    International Nuclear Information System (INIS)

    We examined the impact of electric field on crystal lattice of vanadium dioxide (VO2) in a field-effect transistor geometry by in-situ synchrotron x-ray diffraction measurements. Whereas the c-axis lattice parameter of VO2 decreases through the thermally induced insulator-to-metal phase transition, the gate-induced metallization was found to result in a significant increase of the c-axis length by almost 1% from that of the thermally stabilized insulating state. We also found that this gate-induced gigantic lattice deformation occurs even at the thermally stabilized metallic state, enabling dynamic control of c-axis lattice parameter by more than 1% at room temperature

  17. Evaluacin de desempeo de VoIP en redes MANET / Performance evaluation of VoIP in MANET

    Scientific Electronic Library Online (English)

    Patricia, Sing-Borrajo.

    2014-06-01

    Full Text Available Las redes MANET constituyen una opcin atractiva para soluciones de VoIP en escenarios que se caracterizan por la movilidad de los nodos y donde no exista una infraestructura previamente creada. Sin embargo, el soporte de servicios de voz enfrenta desafos ms rigurosos en redes MANET que los que ap [...] arecen en otras redes. La dinmica con que cambia la topologa causa que algunos parmetros importantes para medir la calidad como el retardo, la prdida de paquetes y la variacin del retardo se vean muy afectados. En este trabajo se mide mediante simulacin el impacto que tienen las mtricas: nmero de saltos, carga de trfico, densidad de los nodos y nmero de interrupciones de ruta en el desempeo de aplicaciones de VoIP en redes MANET. Con los resultados obtenidos se ha podido comprobar que las mtricas estudiadas tienen un comportamiento ms inestable en MANET que en otras redes tambin candidatas a soportar servicios mviles, sin embargo, existe mucha expectativa con la posibilidad de utilizar estas tecnologas (VoIP y MANET) para ofrecer telefona mvil de bajo costo gracias a la facilidad de despliegue y a la sencillez de su infraestructura. Abstract in english MANET networks are an attractive option for VoIP solutions in scenarios that are characterized by the mobility of nodes and where there is not a previously established infrastructure. However, the voice support faces more rigorous challenges in MANET networks than those of others networks. The dynam [...] ic with which topology changes affects important parameters to measure quality such as delay, packet loss and delay variation. In this work we measured the impact of metrics such as hop count, traffic load, node density and number of route breaks have over the performance of VoIP applications in MANET through simulation. Such simulations have allowed the comparison of the behavior of three important routing protocols. From the results reached, it has been shown that the studied metrics have a more unstable behavior in MANET than in other networks that are also candidates to carry mobile services. However, there is a lot of expectation with the possibility of using these technologies (VoIP and MANET) to provide lowcost mobile telephony due to the ease of deployment and simplicity of its infrastructure.

  18. In situ high-pressure synchrotron X-ray diffraction study of the structural stability in NdVO{sub 4} and LaVO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); Popescu, C. [CELLS-ALBA Synchrotron Light Facility, Cerdanyola, 08290 Barcelona (Spain); Achary, S.N.; Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Bettinelli, M. [Luminiscent Materials Laboratory, DB and INSTM, Università di Verona, Strada Le Grazie 15, I-37134 Verona (Italy)

    2014-02-01

    Highlights: • NdVO{sub 4} and LaVO{sub 4} were studied under high pressure using synchrotron powder XRD. • Both compounds exhibit first-order phase transitions. • In NdVO{sub 4} the transition involves a symmetry breaking and in LaVO{sub 4} is isomorphic. • The crystal structures of the high-pressure phases are assigned. • Axial and bulk compressibilities are determined. - Abstract: Room-temperature angle-dispersive X-ray diffraction measurements on zircon-type NdVO{sub 4} and monazite-type LaVO{sub 4} were performed in a diamond-anvil cell up to 12 GPa. In NdVO{sub 4}, we found evidence for a non-reversible pressure-induced structural phase transition from zircon to a monazite-type structure at 6.5 GPa. Monazite-type LaVO{sub 4} also exhibits a phase transition but at 8.6 GPa. In this case the transition is reversible and isomorphic. In both compounds the pressure induced transitions involve a large volume collapse. Finally, the equations of state and axial compressibilities for the low-pressure phases are also determined.

  19. Structural and morphology comparison between m-LaVO4 and LaVO3 compounds prepared by sol-gel acrylamide polymerization and solid state reaction

    International Nuclear Information System (INIS)

    We contrast the production of LaVO3 polycrystalline samples obtained by reduction of m-LaVO4 prepared by sol-gel acrylamide polymerization (SGAP) and solid state reaction (SSR). For SGAP the formation of m-LaVO4 occurs at 400 deg. C, for SSR at 1400 deg. C. For m-LaVO4-SGAP we observe a homogeneous morphology with needle-shaped grains of 50 nm average size. The SSR presents a broader size distribution in the micrometer range. Both m-LaVO4 samples were reduced into LaVO3 using a Zr rod at 850 deg. C in vacuum. LaVO3-SGAP presents a homogeneous grain distribution with an average size of 745 nm. LaVO3-SSR has an average size of 3.45 μm. The stoichiometry of all compounds was confirmed by energy dispersive X-ray spectroscopy. X-ray powder diffraction and transmission electron microscopy give crystal structures in agreement with those reported in the literature.

  20. Charging of SAML-based federated VoIP services

    OpenAIRE

    Lutz, D J; Lamp, D; Mandic, P; Hecht, F.; Stiller, B.

    2010-01-01

    Whilst SAML-based federations are most often used by academic and semi-commercial institutions that focus only on attribute-based authentication, we foresee a growing interest for service providers providing charged services. Since more and more academic and semi-commercial federation participants offer Voice-over-IP (VoIP) services, this type of service provides an entry point into identity federation based payment. Therefore, this paper describes an approach on how to h...

  1. Determinants of peak VO2 in heart transplant recipients

    OpenAIRE

    Vitor Oliveira Carvalho; Guilherme Veiga Guimarães; Marcelo Luiz Campos Vieira; Aparecida Maria Catai; Vagner Oliveira-Carvalho; Silvia Moreira Ayub-Ferreira; Edimar Alcides Bocchi

    2015-01-01

    Objective To establish the determinants of the peak VO2 in heart transplant recipients. Methods Patient's assessment was performed in two consecutive days. In the first day, patients performed the heart rate variability assessment followed by a cardiopulmonary exercise test. In the second day, patients performed a resting echocardiography. Heart transplant recipients were eligible if they were in a stable condition and without any evidence of tissue rejection diagnosed by endomyocardial biops...

  2. Magnetism in Ni2FeVO6-δ

    International Nuclear Information System (INIS)

    The temperature dependence of magnetization M(T) of new polycrystalline ilmenite Ni2FeVO6-δ shows remarkable singularities which can be interpreted as a result of coexistence of three magnetic phases in its magnetic structure. A fit of the dependences following four different models, each of which a combination of three functions of chosen type, to the M(T) experimental dependence has been made. ((orig.))

  3. Implementation of Cloud Computing into VoIP

    Directory of Open Access Journals (Sweden)

    Floriana GEREA

    2012-08-01

    Full Text Available 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 solution presented.

  4. Forensic Acquisition and Analysis of Tango VoIP

    OpenAIRE

    Le-Khac, Nhien-An; Sgaras, Christos; Kechadi, Tahar

    2014-01-01

    The advent of the Internet has significantly transformed the daily activities of millions of people, with one of them being the waypeople communicate where Instant Messaging (IM) and Voice over IP (VoIP) communications have become prevalent. AlthoughIM applications are ubiquitous communication tools nowadays, it was observed that the relevant research on the topic ofevidence collection from IM services was limited. The reason is an IM can serve as a very useful yet very dangerous platform for...

  5. Structural characterization of PrVO3 epitaxial thin films

    OpenAIRE

    Copie, O.; H. Rotella; Boullay, P.; Morales, M.; Pautrat, A.; David, A.; Mercey, B.; Pravarthana, D.; Infante, I.C.; Janolin, P. -E.; Prellier, W.

    2014-01-01

    Rare earth perovskite oxides constitute a wide family of materials presenting functional proper- ties strongly coupled to their crystalline structure. Here, we report on the experimental results on epitaxial PrVO3 deposited on SrTiO3 single crystal substrates by pulsed laser deposition. By com- bining advanced structural characterization tools, we have observed that the PVO unrelaxed film structure grown on STO, is characterized by two kinds of oriented domains whose epitaxial relations are: ...

  6. Structural analysis of strained LaVO$_3$ thin films

    OpenAIRE

    H. Rotella; Copie, O.; Mouillard-Steciuk, G.; Ouerdane, H.; Boullay, P.; ROUSSEL, P; Morales, M.; David, A.; Pautrat, A.; Mercey, B.; L. Lutterotti; Chateigner, D.; Prellier, W.

    2014-01-01

    While structure refinement is routinely achieved for simple bulk materials, the accurate structural determination still poses challenges for thin films due on the one hand to the small amount of material deposited on the thicker substrate and, on the other hand, to the intricate epitaxial relationships that substantially complicate standard X-ray diffraction analysis. Using a combined approach, we analyze the crystal structure of epitaxial LaVO$_3$ thin films grown on (100)-oriented SrTiO$_3$...

  7. TeleInViVo: a collaborative volume visualization application.

    Science.gov (United States)

    Coleman, J; Savchenko, A; Goettsch, A; Wang, K; Bono, P; Littlefield, R; Macedonia, C

    1997-01-01

    Converging technologies in the areas of networks, volume visualization algorithms, and computer performance have made possible the development of a new tool for collaboration, which extends the reach of health professionals, and other consumers of volumetric data around the world. TeleInViVo(tm) is a three-dimensional (3D) collaborative volume visualization tool for medical applications. It extends the capabilities of InViVo(tm), a fast volume visualization tool developed at the Fraunhofer IGD, Darmstadt, Germany [1-3], with efficient and intuitive network collaboration features for remote consultation and new modes of interaction. The software runs on both UNIX and Windows NT platforms. TeleInViVo provides a high degree of interactivity for the medical professional when interacting with the patient data, facilitates explanation and communication between field personnel and medical experts located far from the field, and permits viewing of the data in a multitude of ways designed to support rapid and accurate diagnosis. Current efforts involve architectural enhancements to support multiuser, distributed telemedical scenarios. The application includes the following features: Volume and subvolume data transmission at user specified resolution, Synchronization cues, Integration of Immersion Probe(tm), a 6 degree-of-freedom input device, for ergonomic 3D data exploration, Tools for measuring distances, Tools for planning instrument path, Arbitrary cutting planes in real time, Interactive segmentation tools, Virtual video recorder and playback (cine loops), 3D stereo mode. TeleInViVo is an essential part of the MUSTPAC-1 portable 3D ultrasound system developed by Battelle Pacific Northwest Labs, Richland, WA. PMID:10168908

  8. Effect of W addition on the electrical switching of VO2 thin films

    Science.gov (United States)

    Rajeswaran, Bharathi; Umarji, Arun M.

    2016-03-01

    Vanadium Oxide has been a frontrunner in the field of oxide electronics because of its metal-insulator transition (MIT). The interplay of different structures of VO2 has played a crucial role in deciding the magnitude of the first order MIT. Substitution doping has been found to introduce different polymorphs of VO2. Hence the role of substitution doping in stabilizing the competing phases of VO2 in the thin film form remains underexplored. Consequently there have been reports both discounting and approving such a stabilization of competing phases in VO2. It is reported in the literature that the bandwidth of the hysteresis and transition temperature of VO2 can be tuned by substitutional doping of VO2 with W. In this work, we have adopted a novel technique called, Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) to deposit VO2 and W- doped VO2 as thin films. XRD and Raman spectroscopy were used to investigate the role of tungsten on the structure of VO2 thin films. Morphology of the thin films was found to be consisting of globular and porous nanoparticles of size ˜ 20nm. Transition temperature decreased with the addition of W. We found that for 2.0 at % W doping in VO2, the transition temperature has reduced from 68 o C to 25 o C. It is noted that W-doping in the process of reducing the transition temperature, alters the local structure and also increases room temperature carrier concentration.

  9. Caracterizacin de aerosoles por quema de biomasa en el sureste de Mxico / Characterization of biomass burning aerosols over southeast Mexico

    Scientific Electronic Library Online (English)

    Virginia Edith, Corts-Hernndez; Javier, Aparicio.

    2014-02-01

    Full Text Available La caracterizacin de los aerosoles atmosfricos es de gran importancia en los procesos de transferencia radiativa en la atmsfera y el balance de radiacin del sistema climtico. En este trabajo se presentan algunas propiedades fsicas que forman parte de la caracterizacin ptica y radiativa de lo [...] s aerosoles atmosfricos registrados en dos sitios de monitoreo pertenecientes a la red AERONET, ubicados al sureste de Mxico, durante el periodo 2005-2007. La ubicacin de los dos sitios de monitoreo correspondi a la regin de mayor quema de biomasa por incendios forestales durante el ao 2005. La caracterizacin de los aerosoles atmosfricos consider cuatro casos de estudio: 1) 23 de abril de 2005, en Tenosique, Tabasco; 2) 27 de abril de 2005; 3) 8 de mayo de 2006, y 4) 24 de mayo de 2007, en Tuxtla Gutirrez, Chiapas. Los resultados muestran altos valores del espesor ptico del aerosol (? > 1.4), altos valores del coeficiente de ngstrm (? > 0.8), modos finos de acumulacin del aerosol (r Abstract in english Characterization of aerosols is important for the atmospheric radiative process and the radiation budget of the climate system. This study presents some physical properties forming part of the optical and radiative characterization of atmospheric aerosols measured in two monitoring sites from the AE [...] RONET network located in Southeastern Mexico during 2005-2007. The location of both sites corresponded to the region of high biomass burning activity during 2005. Characterization of aerosols considered four study cases: 1) April 23, 2005 in Tenosique, Tabasco, 2) April 27, 2005, 3) May 8, 2006 and 4) May 24, 2007 in Tuxtla Gutierrez, Chiapas. Results show values of high atmospheric optical depth (? > 1.4), fine accumulation mode particles (r

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

    Directory of Open Access Journals (Sweden)

    Carlos Francisco González Hernández

    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.

  11. Raman phonons in multiferroic FeVO4 crystals

    Science.gov (United States)

    Zhang, An-Min; Liu, Kai; Ji, Jian-Ting; He, Chang-Zhen; Tian, Yong; Jin, Feng; Zhang, Qing-Ming

    2015-12-01

    Multiferroic materials are promising candidates for next-generation multi-functional devices, because of the coexistence of multi-orders and the coupling between the orders. FeVO4 has been confirmed to be a multiferroic compound, since it exhibits both ferroelectricity and antiferromagnetic ordering at low temperatures. In this paper, we have performed careful Raman scattering measurements on high-quality FeVO4 single crystals. The compound has a very rich phonon structure due to its low crystal symmetry (P - 1) and at least 47 Raman-active phonon modes have been resolved in the low and hightemperature spectra. Most of the observed modes are well assigned with aid of first-principles calculations and symmetry analysis. The present study provides an experimental basis for exploring spin-lattice coupling and the mechanism of multiferroicity in FeVO4 Project supported by the National Basic Research Program of China (Grant No. 2012CB921701), the National Natural Science Foundation of China (Grant Nos. 11174367 and 11004243), the China Postdoctoral Science Foundation, the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China (Grant Nos. 10XNI038, 14XNLF06, and 14XNLQ03).

  12. CyberSKA Radio Imaging Metadata and VO Compliance Engineering

    Science.gov (United States)

    Anderson, K. R.; Rosolowsky, E.; Dowler, P.

    2013-10-01

    The CyberSKA project has written a specification for the metadata encapsulation of radio astronomy data products pursuant to insertion into the VO-compliant Common Archive Observation Model (CAOM) database hosted by the Canadian Astronomy Data Centre (CADC). This specification accommodates radio FITS Image and UV Visibility data, as well as pure CASA Tables Imaging and Visibility Measurement Sets. To extract and engineer radio metadata, we have authored two software packages: metaData (v0.5.0) and mddb (v1.3). Together, these Python packages can convert all the above stated data format types into concise FITS-like header files, engineer the metadata to conform to the CAOM data model, and then insert these engineered data into the CADC database, which subsequently becomes published through the Canadian Virtual Observatory. The metaData and mddb packages have, for the first time, published ALMA imaging data on VO services. Our ongoing work aims to integrate visibility data from ALMA and the SKA into VO services and to enable user-submitted radio data to move seamlessly into the Virtual Observatory.

  13. Electronic transport in VO2Experimentally calibrated Boltzmann transport modeling

    Science.gov (United States)

    Kinaci, Alper; Kado, Motohisa; Rosenmann, Daniel; Ling, Chen; Zhu, Gaohua; Banerjee, Debasish; Chan, Maria K. Y.

    2015-12-01

    Materials that undergo metal-insulator transitions (MITs) are under intense study, because the transition is scientifically fascinating and technologically promising for various applications. Among these materials, VO2 has served as a prototype due to its favorable transition temperature. While the physical underpinnings of the transition have been heavily investigated experimentally and computationally, quantitative modeling of electronic transport in the two phases has yet to be undertaken. In this work, we establish a density-functional-theory (DFT)-based approach with Hubbard U correction (DFT + U) to model electronic transport properties in VO2 in the semiconducting and metallic regimes, focusing on band transport using the Boltzmann transport equations. We synthesized high quality VO2 films and measured the transport quantities across the transition, in order to calibrate the free parameters in the model. We find that the experimental calibration of the Hubbard correction term can efficiently and adequately model the metallic and semiconducting phases, allowing for further computational design of MIT materials for desirable transport properties.

  14. Dioxodichlorovanadate [VO2Cl2]-; preparation, vibrational spectrum, and crystal structure of [Ph3PMe][VO2Cl2

    International Nuclear Information System (INIS)

    The title compound was obtained from VO2Cl and [Ph3PMe]Cl in CH2Cl2 solution in form of orange crystals. Its crystal structure was determined with X-ray diffraction data and was refined to a residual index of R = 5.6% (2124 observed, independent reflexions). [Ph3PMe][VO2Cl2] crystallizes in the rhombic space group P212121 = D24 with four formula units in the unit cell. The low symmetry of the space group causes chirality of the cation. The complex anion is in good agreement with Csub(2v) symmetry; it is isoelectronic with CrO2Cl2. The vibrational spectrum (IR, Raman) was recorded and assigned. (author)

  15. 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)

    Ángel Canales-Gutiérrez

    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.

  16. Facile synthesis, phase transition, optical switching and oxidation resistance properties of belt-like VO2(A) and VO2(M) with a rectangular cross section

    International Nuclear Information System (INIS)

    Highlights: ► Belt-like VO2(A) with a rectangular cross section was synthesized. ► The formation mechanism of belt-like VO2(A) was proposed. ► Belt-like VO2(M) was prepared by the irreversible transformation of VO2(A). ► VO2(A) and VO2(M) can be used as the optical switching materials. ► VO2(A) and VO2(M) have good oxidation resistance below 400 °C in air. -- Abstract: Belt-like VO2(A) with a rectangular cross section (VA-RCS) was successfully synthesized using V2O5, H2C2O4·2H2O and H2O as the starting materials by a facile hydrothermal approach. Some synthetic parameters, such as, the reaction time, reaction temperature and concentration of H2C2O4·2H2O, were systematically investigated to control the fabrication of belt-like VA-RCS. The formation mechanism of belt-like VA-RCS was proposed. Subsequently, belt-like VO2(M) with a rectangular cross section (VM-RCS) was prepared by the irreversible transformation of VA-RCS at 700 °C for 2 h under the inert atmosphere. The phase transition temperature (Tc) of VA-RCS and VM-RCS was evaluated by DSC test. The optical switching properties of VA-RCS and VM-RCS were studied by the variable-temperature infrared spectra, and it was found that the as-obtained VA-RCS and VM-RCS could be used as the optical switching materials. Furthermore, the oxidation resistance properties of VA-RCS and VM-RCS were investigated by TGA, indicating that they have good thermal stability and oxidation resistance below 400 °C in air.

  17. Situación actual y perspectivas de futuro de la hibridación térmica solar con biomasa forestal en España

    OpenAIRE

    Turrado Fernández, Sandra

    2014-01-01

    La actual preocupación por el cambio climático y por la necesidad de buscar alternativas sostenibles a los combustibles fósiles ha llevado a la Unión Europea al establecimiento de una serie de objetivos en materia de medio ambiente y energías renovables para el año 2020. La hibridación térmica solar con biomasa forestal se presenta como una tecnología con un papel importante en el cumplimiento de dichos objetivos, por lo que este estudio analizará las posibilidades de su implementación en Esp...

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

    Directory of Open Access Journals (Sweden)

    Esteban Sánchez-Chávez

    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. Estimacin de la biomasa foliar de Prosopis flexuosa mediante relaciones alomtricas Estimation of leaf biomass in Prosopis flexuosa by means of allometric relationships

    Directory of Open Access Journals (Sweden)

    M. Ledesma

    2010-12-01

    Full Text Available La estimacin alomtrica de la biomasa foliar arbrea es necesaria para determinar la produccin primaria y para analizar algunas de las interacciones ecolgicas entre los rboles y los dems componentes de la vegetacin. El objetivo del trabajo fue ajustar y seleccionar modelos para estimar la biomasa foliar de Prosopis flexuosa a partir de variables dendromtricas. Se apearon seis rboles, se midi su dimetro y se calcul el rea de albura de muestras transversales de leo, en cuatro niveles: en los rdenes de ramificacin dentro de la copa viva (ramas secundarias, terciarias y cuaternarias agrupadas, en el extremo distal de las ramas primarias y en los extremos distal y basal del fuste. Se recolectaron las hojas correspondientes a cada nivel y se obtuvo el peso seco. El rea de albura fue la mejor variable predictora de biomasa foliar, aunque el dimetro tuvo buen ajuste en ramas dentro de la copa viva y en ramas primarias. Los modelos calculados con variables de fuste tuvieron menor ajuste. Se concluye que para la estimacin no destructiva de la biomasa foliar de plantas adultas de Prosopis flexuosa es recomendable utilizar el modelo basado en el dimetro distal de las ramas primarias.The estimation of leaf biomass, usually performed by alometric relations, is important for the interpretation of primary production and for the assessment of ecological interactions between trees and the rest of the components in a wood vegetation. The goal for the present work was to adjust and to select allometric models for the estimation of leaf biomass Prosopis flexuosa based on dendrometric variables. Six trees were surveyed. The diameter and sapwood area of transversal samples of wood were determined at four different levels: in the orders of ramification within living crown (secondary, tertiary and quaternary grouped branches, at the distal portions of primary branches and in the apical and basal portions of bole. The leaves were collected according to each level and dry mass was obtained. The sapwood area was the best predictor of leaf biomass, although diameter provided accurate estimations within crown and at the distal portions of primary branches. The models based on trunk dimensions were less precise. It is concluded that the obtained regression model based on the diameter of the distal portions of primary branches can be applied for the non-destructive estimation of leaf biomass in Prosopis flexuosa adult trees.

  20. Influencia de la aplicacin de vinaza en actividad y biomasa microbiana en un entic dystropept y un fluventic haplustoll del valle del cauca, colombia

    OpenAIRE

    Sandra Patricia Montenegro Gmez; Juan Carlos Menjivar Flrez; Carmen Rosa Bonilla Correa; Ral Madrin Molina

    2009-01-01

    Con la aplicacin de vinaza, residuo de la produccin de alcohol carburante a partir de la caa de azcar, se evalu el efecto sobre la actividad y biomasa microbiana del suelo y el suministro de K+ al cultivo de maz dulce (Zea Mays)...

  1. Determinacin de carbono orgnico total presente en el suelo y la biomasa de los pramos de las comunidades de chimborazo y shobol llinllin en Ecuador

    Directory of Open Access Journals (Sweden)

    M. Echeverra

    2013-01-01

    Full Text Available En la determinacin del contenido de carbono orgnico total presente en el suelo y la biomasa (cobertura vegetal de los pramos de las comunidades de Chimborazo, con 210ha de pramo cuya ubicacin es 746667UTM-9825400UTM, y Shobol Llinlln, con 350 ha de pramo, 754680UTM9854678UTM, pertenecientes a San Juan en Ecuador, se seleccionaron 9 puntos de muestreo de acuerdo a la variacin, caractersticas y altitud del suelo, repartidos para este estudio en tres pisos altitudinales comprendidos, para el pramo de la comunidad Chimborazo, entre 3600-3900 msnm y, en el caso de Shobol Llinlln, entre 3600-3950 msnm.

  2. Estudio de la oxidación a elevada temperatura de ocho aleaciones en atmósferas de combustión de biomasa

    Directory of Open Access Journals (Sweden)

    Berlanga-Labari, C.

    2008-08-01

    Full Text Available The combustion of biomass, especially wheat straw, generates very corrosive media particularly near the superheater tubes. Chlorine is known to be the main corrosive agent in biomass-fired plants. This paper focuses on the study of the corrosivity of such environments composed of gases and ashes, at high temperature, on eight commercial alloys with different chromium and nickel contents. These have been: AISI 347 CG (1.4550, AISI 347 FG(1.4550, AISI 316LN (1.4910, ESSHETE 1250 (1.4982, AC 66 (1.4877, X20CrMoV12:1 (1.4922 and AISI 347 coated with Inconel 625 and Inconel 686. Corrosion tests in the boiler have been performed during 8.000 h and 15.000 h at temperatures between 500 °C y 550 °C in the biomass plant of Sangüesa (Navarra, Spain. Experimental results showed an unacceptable behaviour far the martensitic steel, acceptable far the austenitics and good far the inconels. The appearance of the corrosion attack was also investigated to obtain understanding of the corrosion mechanism. The corrosion mechanism by molten salts has been rejected. The active oxidation corrosion mechanism has been proposed as the most probable in order to interpretate the corrosion behaviour of these materials in these environments.

    La combustión de biomasa, especialmente de paja de cereal, genera un ambiente muy corrosivo, particularmente, cerca de los tubos sobrecalentadores. El cloro es el principal agente corrosivo en las plantas de biomasa. Este trabajo se centra en comprobar el comportamiento de ocho aleaciones comerciales en una ambiente de combustión de biomasa. Los materiales estudiados han sido las siguientes: AISI 347 CG (1.4550, AISI 347 FG (1.4550, AISI 316LN (1.4910, ESSHETE 1250 (1.4982, AC 66 (1.4877, X20CrMoV12:1 (1.4922 y AISI 347 recubiertos con Inconel 625 e Inconel 686. Los ensayos se han realizado en la caldera de la planta de biomasa de Sangüesa (Navarra, España durante 8.000 y 15.000 h a una temperatura de 500-550 °C. Los resultados indican un buen comportamiento de los aceros inoxidables austeníticos y de las aleaciones de Inconel, mientras que el del acero martensítico no ha sido aceptable. Se ha propuesto el mecanismo conocido como “oxidación activa” para interpretar el comportamiento a la corrosión de estos materiales en estos medios.

  3. Cambio en el PSI y la RAS de un suelo y su influencia en la actividad biológica y la biomasa microbiana

    OpenAIRE

    Gasca Valderrama, Cesar Augusto

    2010-01-01

    Con el objetivo de evaluar los cambios en el PSI, la RAS y su influencia en la actividad y biomasa mircrobiana del suelo, se aplicaron diversos tratamientos con 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 diseño en bloques completos al azar con cuatro tratamientos y tres repeticiones, y se evaluaron las propiedades del suelo: Actividad biológic...

  4. Desempeño productivo de pollos de engorde suplementados con biomasa de saccharomyces cerevisiae derivada de la fermentación de residuos de banano

    OpenAIRE

    Medina, N. M.; González, C A; Daza, S. L.; Restrepo, O.; Barahona Rosales, R.

    2014-01-01

    El objetivo de esta investigación fue evaluar el efecto de la inclusión de diferentes niveles de biomasa de levaduras producidas al fermentar hidrolizados de residuos de la industria bananera sobre los parámetros zootécnicos de pollos de engorde, evaluando además el impacto económico de su uso en las dietas. El estudio se realizó en el Centro Agrario San Pablo de la Universidad Nacional Sede Medellín. Se utilizaron 210 pollos de engorde de un día de edad, distribuidos completamente al azar en...

  5. Relación entre la biomasa y algunas características morfológicas de las bromelias fitotelmatas de un bosque alto andino colombiano

    OpenAIRE

    Isaza, Carolina; BETANCUR, JULIO

    2012-01-01

    Se evaluaron algunas características morfológicas para seis especies de bromelias fitotelmata (Guzmania gloriosa, Racinaea tetrantha, Tillandsia biflora, T. complanata, T. fendleri y T. turneri) con el fin de establecer cuales características podrían utilizarse como estimadores indirectos de la biomasa total de la planta. El estudio se realizó en un bosque alto andino de la Sabana de Bogotá, Colombia, ubicado a 2900 m de altitud. Para cada especie se recolectaron entre 32 y 64 individuos en d...

  6. Efecto de lixiviados del raquis de plátano sobre la actividad y biomasa microbiana en floración y cosecha del tomate

    OpenAIRE

    Muñoz V. Rosa Elvira; Madriñán Molina R.

    2006-01-01

    Se utilizaron cinco tratamientos: el testigo (T0) y cuatro concentraciones de lixiviados (T1= 100%, T2= 75%, T3= 50% y T4= 25%) aplicados 15, 30 y 60 días después del trasplante. La actividad microbiana se determinó con la metodología del CAB y la biomasa microbiana con el método de fumigación-extracción. En la actividad microbiana se encontraron diferencias significativas entre los tratamientos, presentando la aplicación del lixiviado a la menor concentración (25%) la mayor actividad (56.76 ...

  7. Densidad y biomasa de macroinvertebrados acuáticos derivantes en una quebrada tropical de montaña (bogotá, colombia)

    OpenAIRE

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

    2013-01-01

    Se estimó la variación en la densidad de deriva de macroinvertebrados acuáticos y suaporte de materia orgánica en términos de biomasa de diferentes estados inmadurose imagos, en un tramo de una quebrada tropical de montaña ubicada en los cerrosorientales 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 con194 individuos (abundancia total). La densidad de deriva al igual que el aporte debiomasa...

  8. Biomass and densityofthalassia testudinum beds in mochimabay, Venezuela Biomasa y densidad de praderas de thalassia testudinum en la bahía de mochima, Venezuela

    OpenAIRE

    Díaz-Díaz,Oscar; Liñero-Arana, Ildefonso

    2007-01-01

    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 mens...

  9. CO Oxidation Promoted by the Gold Dimer in Au2 VO3 (-) and Au2 VO4 (-) Clusters.

    Science.gov (United States)

    Wang, Li-Na; Li, Zi-Yu; Liu, Qing-Yu; Meng, Jing-Heng; He, Sheng-Gui; Ma, Tong-Mei

    2015-09-28

    Investigations on the reactivity of atomic clusters have led to the identification of the elementary steps involved in catalytic CO oxidation, a prototypical reaction in heterogeneous catalysis. The atomic oxygen species O(.-) and O(2-) bonded to early-transition-metal oxide clusters have been shown to oxidize CO. This study reports that when an Au2 dimer is incorporated within the cluster, the molecular oxygen species O2 (2-) bonded to vanadium can be activated to oxidize CO under thermal collision conditions. The gold dimer was doped into Au2 VO4 (-) cluster ions which then reacted with CO in an ion-trap reactor to produce Au2 VO3 (-) and then Au2 VO2 (-) . The dynamic nature of gold in terms of electron storage and release promotes CO oxidation and O-O bond reduction. The oxidation of CO by atomic clusters in this study parallels similar behavior reported for the oxidation of CO by supported gold catalysts. PMID:26267648

  10. Carbon quantum dots coated BiVO{sub 4} inverse opals for enhanced photoelectrochemical hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Nan, Feng; Shen, Mingrong; Fang, Liang, E-mail: zhkang@suda.edu.cn, E-mail: lfang@suda.edu.cn [College of Physics, Optoelectronics and Energy and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006 (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn, E-mail: lfang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Wang, Junling [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2015-04-13

    Carbon quantum dots (CQDs) coated BiVO{sub 4} inverse opal (io-BiVO{sub 4}) structure that shows dramatic improvement of photoelectrochemical hydrogen generation has been fabricated using electrodeposition with a template. The io-BiVO{sub 4} maximizes photon trapping through slow light effect, while maintaining adequate surface area for effective redox reactions. CQDs are then incorporated to the io-BiVO{sub 4} to further improve the photoconversion efficiency. Due to the strong visible light absorption property of CQDs and enhanced separation of the photoexcited electrons, the CQDs coated io-BiVO{sub 4} exhibit a maximum photo-to-hydrogen conversion efficiency of 0.35%, which is 6 times higher than that of the pure BiVO{sub 4} thin films. This work is a good example of designing composite photoelectrode by combining quantum dots and photonic crystal.

  11. Carbon quantum dots coated BiVO4 inverse opals for enhanced photoelectrochemical hydrogen generation

    International Nuclear Information System (INIS)

    Carbon quantum dots (CQDs) coated BiVO4 inverse opal (io-BiVO4) structure that shows dramatic improvement of photoelectrochemical hydrogen generation has been fabricated using electrodeposition with a template. The io-BiVO4 maximizes photon trapping through slow light effect, while maintaining adequate surface area for effective redox reactions. CQDs are then incorporated to the io-BiVO4 to further improve the photoconversion efficiency. Due to the strong visible light absorption property of CQDs and enhanced separation of the photoexcited electrons, the CQDs coated io-BiVO4 exhibit a maximum photo-to-hydrogen conversion efficiency of 0.35%, which is 6 times higher than that of the pure BiVO4 thin films. This work is a good example of designing composite photoelectrode by combining quantum dots and photonic crystal

  12. Continuous tuning of W-doped VO2 optical properties for terahertz analog applications

    International Nuclear Information System (INIS)

    Vanadium dioxide (VO2), with its characteristic metal-insulator phase transition, is a prospective active candidate to realize tunable optical devices operating at terahertz (THz) frequencies. However, the abrupt phase transition restricts its practical use in analog-like continuous applications. Incorporation of tungsten is a feasible approach to alter the phase transition properties of thin VO2 films. We show that amplitude THz modulation depth of ?65%, characteristic phase transition temperature of ?40?C, and tuning range larger than 35?C can be achieved with W-doped VO2 films grown on sapphire substrates. W-doped VO2 films can also be used to suppress Fabry-Perot resonances at THz frequencies but at temperatures much lower than that observed for undoped VO2 films. The gradual phase transition temperature window allows for precise control of the W-doped VO2 optical properties for future analog based THz devices

  13. 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...

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

    Directory of Open Access Journals (Sweden)

    Eduardo P. Prez

    2005-11-01

    Full Text Available RESUMEN. Entre septiembre de 1997 y agosto de 2000 se realiz un seguimiento diario de la dinmica espacial y temporal de la CPUE (tonlance-1 de camarn nailon por parte de la flota arrastrera con puerto base en Coquimbo. Se construy un modelo de remocin de biomasa modificado para explicar las variaciones 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 travs del tiempo y el reclutamiento (magnitud y temporalidad. El modelo modificado indic dos perodos anuales de distinta longitud en la disponibilidad de biomasa al arte de pesca. Tambin indic una tasa de reduccin ms acelerada para la biomasa que para la CPUE. Los resultados pueden influir en la determinacin de la poca ptima para la realizacin de las evaluaciones directas del recurso con fines de determinar cuotas de capturaA daily record of space/time dynamics was carried out on CPUE (tontrawl-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 abundance (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

  15. A study of mobile VoIP performance in wireless broadband networks

    OpenAIRE

    Andres ARJONA

    2009-01-01

    Voice service is to date still the killer mobile service and the main source for operator revenue for years to come. Additionally, voice service will evolve from circuit switched technologies towards packet based Voice over IP (VoIP). However, using VoIP over wireless networks different from 3GPP cellular technologies makes it also a disruptive technology in the traditional telecommunication sector. The focus of this dissertation is on determining mobile VoIP performance in different wir...

  16. Secure Communication and VoIP Threats in Next Generation Networks

    OpenAIRE

    M. Hossein Ahmadzadegan; M. Elmusrati; Mohammadi, H.

    2013-01-01

    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 vulnerabili...

  17. Comparative Study of VoIP over WiMax and WiFi

    OpenAIRE

    M Atif Qureshi; Arjumand Younus; Muhammad Saeed; Farhan Ahmed Sidiqui; Nasir Touheed; M Shahid Qureshi

    2011-01-01

    VoIP is a technology in great demand these days. Its interactive nature makes it very appealing for users and today it is one of the most dominant technologies for communication. With the growth over wireless networks the option to have voice communication over wireless has been considered - the choices are VoIP over WiFi or VoIP over WiMax. This paper studies and compares the two options and summarizes the results.

  18. Peer-to-Peer VoIP Communications Using Anonymisation Overlay Networks

    OpenAIRE

    Ge ZHANG; Fischer-Hübner, Simone

    2010-01-01

    Nowadays, Voice over Internet Protocol (VoIP) which enables voice conversation remotely over packet switched networks gains much attentions for its low costs and flexible services. However, VoIP calling anonymity, particularly to withhold "who called whom", is difficult to achieve since VoIP infrastructures are usually deployed in an open networking environment (e.g., the Internet). Our work studies an anonymisation overlay network (AON) based solution to prevent surveillance from external at...

  19. Impact of VoIP and QoS on Open and Distance Learning

    Science.gov (United States)

    Saxena, P. C.; Jasola, Sanjay; Sharma, Ramesh C.

    2006-01-01

    Voice over Internet Protocol (VoIP) is becoming a reality in many organizations. The potential for mobility in voice over wi-fi networks will derive demand for the technology. Wireless VoIP is poised to rival VoIP as an alternative telephony tool. Internet has been used to transport data in the form of packet. In the past, Internet did not support…

  20. The metropolitan VoD system based on ethernet/SCM PON

    Science.gov (United States)

    Ji, Wei; Yang, Hongliang; Feng, Dejun; Liu, Yang; Sun, Jande

    2008-11-01

    VoD is a very attractive service which used for entertainment, education and other purposes. In this paper, we present an evolution method that integrates the EPON and SCM-PON by WDM technology to provide high dedicated bandwidth for the metropolitan VoD services. Using DVB, IPTV protocol, unicasting and broadcasting method to maximize the system throughput and by numerical analysis, the hybrid PON system can implement the metropolitan VoD services.

  1. VoIP Server HW/SW Codesign for Multicore Computing

    OpenAIRE

    Iqbal, Arshad

    2012-01-01

    Modern technologies are growing and Voice over Internet Protocol (VoIP) technology is able to function in heterogeneous networks. VoIP gained wide popularity because it offers cheap calling rates compared to traditional telephone system and the number of VoIP subscribers has increased significantly in recent years. End users need reliable and acceptable call quality in real time communication with best Quality of Service (QoS). Server complexity is increasing to handle all client requests sim...

  2. Gas-phase reactivity of metavanadate [VO3]- towards methanol and ethanol: experiment and theory.

    Science.gov (United States)

    Waters, Tom; Wedd, Anthony G; O'Hair, Richard A J

    2007-01-01

    The gas-phase reactivity of the metavanadate anion [VO3]- towards methanol and ethanol was examined by a combination of ion-molecule reaction and isotope labelling experiments in a quadrupole ion-trap mass spectrometer. The experimental data were interpreted with the aid of density functional theory calculations. [VO3]- dehydrated methanol to eliminate water and form [VO2(eta2-OCH2)]-, which features an [eta2-C,O-OCH2]2- ligand formed by formal removal of two protons from methanol and which is isoelectronic with peroxide. [VO3]- reacted with ethanol in an analogous manner to form [VO2(eta2-OCHCH3)]-, as well as by loss of ethene to form [VO2(OH)2]-. The calculations predicted that important intermediates in these reactions were the hydroxo alkoxo anions [VO2(OH)(OCH2R)]- (R: H, CH3). These were predicted to undergo intramolecular hydrogen-atom transfer to form [VO(OH)2(eta1-OCHR)]- followed by eta1-O-->eta2-C,O rearrangements to form [VO(OH)2(eta2-OCHR)]-. The latter reacted further to eliminate water and generate the product [VO2(eta2-OCHR)]-. This major product observed for [VO3]- is markedly different from that observed previously for [NbO3]- containing the heavier Group 5 congener niobium. In that case, the major product of the reaction was an ion of stoichiometry [Nb, O3, H2]- arising from the formal dehydrogenation of methanol to formaldehyde. The origin of this difference was examined theoretically and attributed to the intermediate alkoxo anion [NbO2(OH)(OCH3)]- preferring hydride transfer to form [HNbO2(OH)]- with loss of formaldehyde. This contrasts with the hydrogen-atom-transfer pathway observed for [VO2(OH)(OCH3)]-. PMID:17661322

  3. Transmission increase upon switching of VO2 thin films on microstructured surfaces

    OpenAIRE

    KARAKURT, ?smail; Boneberg, Johannes; Leiderer, Paul; Lopez, R.; Halabica, A.; Richard F. Haglund

    2007-01-01

    The authors compare transmission measurements of near-infrared light through VO2 thin films on smooth substrates and on ordered arrays of silica microspheres. When the samples are heated above the critical temperature for the semiconductor-metallic phase transition, smooth thin films show reduced transmission independent of thickness; however, the VO2 film deposited on the microspheres may show either reduced or enhanced transmission, depending on VO2 film thickness. They show that this at a ...

  4. Transmission increase upon switching VO2 thin films on microstructured surfaces

    OpenAIRE

    Karakurt, Ismail; Boneberg, Johannes; Leiderer, Paul; Lopez, Rene; Halabica, Andrej; Haglund, Richard

    2007-01-01

    The authors compare transmission measurements of near-infrared light through VO2 thin films on smooth substrates and on ordered arrays of silica microspheres. When the samples are heated above the critical temperature for the semiconductor-metallic phase transition, smooth thin films show reduced transmission independent of thickness: however, the VO2 film deposited on the microspheres may show either reduced or enhanced transmission, depending on VO2 film thickness. They show that this at a ...

  5. Feasibility study of VoIP integration into the MYSEA environment

    OpenAIRE

    Tse, Lily.

    2005-01-01

    Voice over Internet Protocol (VoIP) is becoming popular due to its low cost and the management advantages it offers over traditional PSTN phone systems. VoIP is widely implemented with H.323 and Session Initiation Protocol (SIP) standards. However, both protocols are poorly designed for networks with common security solutions such as firewalls and Network Address Translation (NAT). This project is a feasibility study of SIP-based VoIP integration into the Monterey Security Architecture (M...

  6. VoIP Technology: Investigation of QoS and Security Issues

    OpenAIRE

    Amor Lazzez

    2014-01-01

    Voice over IP (VoIP) is the technology allowing voice traffic transmission as data packets over a private or a public IP network. VoIP allows significant benefits for customers and communication services providers. The main are cost savings, rich media service, phone and service portability and mobility, and the integration with other applications. Nevertheless, the deployment of the VoIP technology encounters many challenges such as architecture complexity, interoperability problems, QoS co...

  7. Instantaneous Band Gap Collapse in Photoexcited Monoclinic VO2 due to Photocarrier Doping

    OpenAIRE

    Wegkamp, D.; Herzog, M.; Xian, L; Gatti, M.; Cudazzo, P.; McGahan, C.; Marvel, R.; Haglund, R.; Rubio, A.; Wolf, M.; Sthler, J.

    2014-01-01

    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 insulato...

  8. 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.

  9. LA SUSTITUCIÓN DE LA SABANA NATIVA POR PLANTACIONES DE PINO Y LA VARIABILIDAD TEMPORAL EN LA BIOMASA MICROBIANA Y LA MINERALIZACIÓN DEL CARBONO Y NITRÓGENO EN EL SUELO

    Directory of Open Access Journals (Sweden)

    Yrma G\\u00F3mez

    2010-01-01

    biomasa microbiana presente en la plantación de pino, así como la menor actividad ineralizadora del C y el N en esta plantación, sugieren, que una mayor preservación de estos nutrientes ocurre en pinares; lo cual favorece la calidad del suelo. La dinámica temporal de la biomasa microbiana en la sabana nativa y en la plantación de pino no está acoplada a la variación temporal de la mineralización del C y el N de estos sistemas.

  10. Distribución de biomasa de Barleria lupulina Lindl. en respuesta a tres regímenes de riego Biomass distribution of Barleria lupulina Lindl. in response to three watering regimes

    OpenAIRE

    V Paz; Vera, A; A Páez

    2003-01-01

    Barleria lupulina es un planta con propiedades medicinales potenciales, cuya acumulación de fitomasa, a nivel de sus órganos, ha sido poco investigada. Se determinó la distribución de biomasa de B. lupulina Lindl. en respuesta a tres regímenes de riego. Se diseñaron, por triplicado, tres tratamientos de riego: cada 2 (RI), 5 (RII) y 15 (RIII) días. Se realizaron mediciones del contenido relativo de agua (CRA), el potencial hídrico, y determinaciones de área foliar y biomasa seca a los seis me...

  11. Active Timing Based Approach for Tracking Anonymous Peer-to-peer Network in VoIP

    OpenAIRE

    Karthikeyan C; Karthikeyan V; Jerin Sajeev.C.R,; Merlin Moses.M,

    2013-01-01

    Peer-to-peer VoIP calls are popular due to theirlow cost and convenience. When these calls are encrypted andanonymized the network becomes a secured one. Tracing of theanonymous VoIP call users are important and the tracedinformation about them should be sent to the server to knowhow long the users are in communication.The key challenge in tracking encrypted VoIP calls acrossanonymous communication system is to identify the correlationbetween the VoIP flows of the caller and the callee. Since...

  12. On-line Monitoring of VoIP Quality Using IPFIX

    OpenAIRE

    Petr Matousek; Martin Kmet; Martin Basel

    2014-01-01

    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 incorporate...

  13. 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 weaknesses such as t...

  14. Optimization of thermochromic VO2-based structures with tunable thermal emissivity

    International Nuclear Information System (INIS)

    In this paper we design and simulate VO2/metal multilayers to obtain a large tunability of the thermal emissivity of IR filters in the typical MWIR window of many infrared cameras. The multilayer structure is optimized to realise a low-emissivity filter at high temperatures useful for military purposes. The values of tunability found for VO2/metal multilayers are larger than the value for a single thick layer of VO2. Innovative SiO2/VO2 synthetic opals are also investigated to enhance the optical tunability by combining the properties of a 3D periodic structure and the specific optical properties of vanadium dioxide.

  15. A Novel Protocol Design and Collaborative Forensics Mechanism for VoIP Services

    OpenAIRE

    Hsien-Ming Hsu; Feng-Yu Lin; Yeali sunny Sun; Meng Chang Chen

    2012-01-01

    The simplicity and low cost of Voice over Internet Protocol (VoIP) services has made these services increasingly popular as the Internet has grown. Unfortunately, these advantages of VoIP are attractive to both legitimate and nefarious users, and VoIP is often used by criminals to communicate and conduct illegal activities (such as fraud or blackmail) without being intercepted by Law Enforcement Agencies (LEAs). However, VoIP can also increase the efficiency of law e...

  16. VV and VO2 defects in silicon studied with hybrid density functional theory

    KAUST Repository

    Christopoulos, Stavros Richard G

    2014-12-07

    The formation of VO (A-center), VV and VO2 defects in irradiated Czochralski-grown silicon (Si) is of technological importance. Recent theoretical studies have examined the formation and charge states of the A-center in detail. Here we use density functional theory employing hybrid functionals to analyze the formation of VV and VO2 defects. The formation energy as a function of the Fermi energy is calculated for all possible charge states. For the VV and VO2 defects double negatively charged and neutral states dominate, respectively.

  17. VoIP Communications over WLANs : Implementation of a new downlink transmission protocol

    OpenAIRE

    Zerouali, Mehdi

    2010-01-01

    Voice over IP (VoIP) is becoming more and more popular every day. The number of VoIP service providers is continuously increasing along with the number of customers they serve. Moreover, the latest generation of smartphones and mobile devices now incorporate VoIP support. This enables users within a wireless local area network (WLAN) cell to exchange VoIP traffic with other peers. This new traffic potentially poses a problem for WLANs, as the WLAN access point could be required to handle a la...

  18. 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

  19. 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.

  20. Consideraciones sobre la producción de etanol a partir de la biomasa lignocelulósica

    Directory of Open Access Journals (Sweden)

    José C. Villar

    2008-01-01

    Full Text Available En los últimos años, como consecuencia del aumento de los precios del petróleo y las exigencias ecológicas, ha crecido el interés por la producción de bioetanol como combustible de vehículos automotores. En Brasil y EEUU, los principales productores, se estima una producción por cada país en el 2006 de alrededor de los 19 mil millones de litros. Brasil planea aumentar la producción hasta 26.5 mil millones en el 2016 mientras que para esa misma fecha EEUU pretende alcanzar los 45,4 mil millones de litros. Las materias primas más empleadas son maíz y caña de azúcar. Sería de interés incluir entre éstas a la biomasa lignocelulósica que se obtiene como subproductos agrícolas y forestales (pajas de cereales, bagazo, aserrín y virutas de madera que no son aptos para el consumo humano y por su composición química son susceptibles de ser sacarificados por hidrólisis química o enzimática. Se analizan críticamente las posibles vías para desarrollar la producción de alcohol a partir de estos materiales, en especial la vía química, cuya perspectiva de éxito se encuentra estrechamente vinculada al desarrollo de reactores continuos. De esta manera, se pueden intensificar las condiciones de reacción que permitan incrementar la productividad del proceso, mediante la obtención de los máximos rendimientos de azúcares con el empleo de los menores volúmenes del equipamiento, sin descuidar la disminución de la concentración de sustancias inhibidoras de la fermentación en el sistema.

  1. Evaluacin agronmica y nutricional del pasto Ryegrass perenne tetraploide (Lolium perenne producido en lecheras de las zonas altas de Costa Rica. I. Produccin de biomasa y fenologa

    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 hectrea y su porcentaje de utilizacin promedio para todas las fincas fueron 4110, 2276 y 1833 kg.ha-1 por corte y 44,82%, respectivamente. La edad fenolgica y la relacin hoja: tallo promedio de las pasturas de ryegrass perenne fueron 2,84 hojas verdes por rebrote, 56:44. Asimismo, la composicin promedio de la pradera fue 76,09% ryegrass, 13,76% otras gramneas (principalmente pasto kikuyo, 6,02% trbol, 1,25% malezas y 2,88% material senescente, respectivamente. La mayor produccin de biomasa durante marzo y abril puede conservarse para utilizarse durante las pocas crticas de disponibilidad de forraje o cuando por razones climatolgicas se reduce el nmero de horas efectivas de pastoreo. La evaluacin de la edad fenolgica en que se pastorea el pasto ryegrass perenne, indica que las fincas en la zona de estudio utilizan esta gramnea en un estado en el que sus reservas de carbohidratos se han recuperado, lo que permite obtener una produccin de biomasa y valor nutricional adecuados para satisfacer las necesidades del ganado lechero de la zona.

  2. Efectos de vinazas sobre bacterias rizosfricas y en la actividad-CO2 y biomasa-C microbiana de un suelo Pachic Haplustoll

    Directory of Open Access Journals (Sweden)

    Miriam Rosero G

    2013-04-01

    Full Text Available En condiciones de casa de malla de la Universidad Nacional de Colombia sede Palmira se estudi los efectos de la aplicacin de vinaza, un subproducto de la industria de alcohol carburante, sobre las bacterias rizosfricas Pseudomonas fluorescens y Bacillus subtilis promotoras de crecimiento, la actividad-CO2, biomasa microbiana-C y el cociente metablico-qCO2 en un suelo Pachic Haplustoll y su relacin con el rendimiento de habichuela (Phaseolus vulgaris L.. Se utiliz un diseo completamente al azar con siete tratamientos y cinco repeticiones. Los tratamientos se seleccionaron con base en los requerimientos de K del cultivo (150 kg/ha K2O utilizando como fuentes KCl y vinaza solos y en mezclas. Los tratamientos evaluados y la poca de muestreo influyeron (P < 0.05 en la actividad y biomasa microbiana. Los menores valores de estas variables se presentaron en la poca de floracin del cultivo cuando la demanda de nutrientes es alta. La mezcla en partes iguales de vinaza y KCl favorece la mayor produccin de habichuela sin afectar la actividad microbiana; el cociente metablico indic estabilidad del sistema en el tiempo y las bacterias rizosfricas presentaron el mejor crecimiento en la mezcla 75% de potasio como vinaza y 25% como KCl.

  3. Predicción del contenido intracelular de trehalosa en el proceso de producción de biomasa de Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    J. S. Aranda

    2008-01-01

    Full Text Available La trehalosa es un carbohidrato dimérico componente de la levadura de panificación Saccharomyces cerevisiae, y es considerado como indicador de la capacidad fermentativa y de la viabilidad de las células. En procesos de producción de levadura, se busca inducir una acumulación intracelular de trehalosa. Por ser un compuesto citoplásmico, la cuantificación de la trehalosa requiere de tomas de muestra y de métodos analíticos posteriores. Así, el conocimiento del contenido citoplásmico de trehalosa es siempre ulterior al desarrollo del proceso de producción de biomasa, y esto dificulta el ajuste en tiempo real de parámetros de operación para incrementar la cantidad de trehalosa en la biomasa. Por tanto, se requiere de alguna alternativa para estimación de la trehalosa intracelular en tiempo real. Este trabajo presenta una opción de predicción basada tanto en el metabolismo celular implicado durante la biosíntesis de trehalosa, como en un algoritmo de redes neuronales dinámicas para la estimación de la concentración intracelular del carbohidrato.

  4. Ultrafast dynamics during the photoinduced phase transition in VO2

    Science.gov (United States)

    Wegkamp, Daniel; Sthler, Julia

    2015-12-01

    The phase transition of VO2 from a monoclinic insulator to a rutile metal, which occurs thermally at TC = 340 K, can also be driven by strong photoexcitation. The ultrafast dynamics during this photoinduced phase transition (PIPT) have attracted great scientific attention for decades, as this approach promises to answer the question of whether the insulator-to-metal (IMT) transition is caused by electronic or crystallographic processes through disentanglement of the different contributions in the time domain. We review our recent results achieved by femtosecond time-resolved photoelectron, optical, and coherent phonon spectroscopy and discuss them within the framework of a selection of latest, complementary studies of the ultrafast PIPT in VO2. We show that the population change of electrons and holes caused by photoexcitation launches a highly non-equilibrium plasma phase characterized by enhanced screening due to quasi-free carriers and followed by two branches of non-equilibrium dynamics: (i) an instantaneous (within the time resolution) collapse of the insulating gap that precedes charge carrier relaxation and significant ionic motion and (ii) an instantaneous lattice potential symmetry change that represents the onset of the crystallographic phase transition through ionic motion on longer timescales. We discuss the interconnection between these two non-thermal pathways with particular focus on the meaning of the critical fluence of the PIPT in different types of experiments. Based on this, we conclude that the PIPT threshold identified in optical experiments is most probably determined by the excitation density required to drive the lattice potential change rather than the IMT. These considerations suggest that the IMT can be driven by weaker excitation, predicting a transiently metallic, monoclinic state of VO2 that is not stabilized by the non-thermal structural transition and, thus, decays on ultrafast timescales.

  5. TAPAS, a VO archive at the IRAM 30-m telescope

    Science.gov (United States)

    Leon, Stephane; Espigares, Victor; Ruíz, José Enrique; Verdes-Montenegro, Lourdes; Mauersberger, Rainer; Brunswig, Walter; Kramer, Carsten; Santander-Vela, Juan de Dios; Wiesemeyer, Helmut

    2012-07-01

    Astronomical observatories are today generating increasingly large volumes of data. For an efficient use of them, databases have been built following the standards proposed by the International Virtual Observatory Alliance (IVOA), providing a common protocol to query them and make them interoperable. The IRAM 30-m radio telescope, located in Sierra Nevada (Granada, Spain) is a millimeter wavelength telescope with a constantly renewed, extensive choice of instruments, and capable of covering the frequency range between 80 and 370 GHz. It is continuously producing a large amount of data thanks to the more than 200 scientific projects observed each year. The TAPAS archive at the IRAM 30-m telescope is aimed to provide public access to the headers describing the observations performed with the telescope, according to a defined data policy, making as well the technical data available to the IRAM staff members. A special emphasis has been made to make it Virtual Observatory (VO) compliant, and to offer a VO compliant web interface allowing to make the information available to the scientific community. TAPAS is built using the Django Python framework on top of a relational MySQL database, and is fully integrated with the telescope control system. The TAPAS data model (DM) is based on the Radio Astronomical DAta Model for Single dish radio telescopes (RADAMS), to allow for easy integration into the VO infrastructure. A metadata modeling layer is used by the data-filler to allow an implementation free from assumptions about the control system and the underlying database. TAPAS and its public web interface ( http://tapas.iram.es ) provides a scalable system that can evolve with new instruments and observing modes. A meta description of the DM has been introduced in TAPAS in order to both avoid undesired coupling between the code and the DM and to provide a better management of the archive. A subset of the header data stored in TAPAS will be made available at the CDS.

  6. Synthesis of Nanostructured Inverse Spinel LiCuVO4

    Science.gov (United States)

    Mai, Liqiang; Chen, Wen; Xu, Qing; Zhu, Quanyao; Peng, Junfeng

    2003-03-01

    Li-ion batteries have recently received considerable interests as rechargeable power sources for room temperature consumer applications since the commercialization of Sony¡¯s lithium-ion cell in 1990[1-3]. In our work, a new method by using citrate acid as complex reagent was introduced for preparing inverse spinel LiCuVO4 as novel high-voltage cathode material for Li-ion batteries. Investigations were conducted by XRD, DSC and TG, SEM and EDAX, TEM, etc. The results of XRD and thermal analysis show the high crystalline LiCuVO4 with high phase purity are formed at low temperature. The results of the IR and Raman investigations show that the band located at about 819 cm-1 corresponding to the stretching vibration mode with the A1 symmetry, whereas the band situated at 332 cm-1 corresponds to the bending mode of the VO4 tetrahedron with E symmetry. The SEM and EDAX results show that the average diameter of the original particles is 100 nm and the distributions of particle diameter and elements are even. References [1] Mai L.Q., Zou Z.G., Chen H.Y.: Mater. Rev., Vol. 14((2000), p.32. [2] Chen W., Xu Q., Hu Y.S., Mai L.Q., Zhu Q. Y.: J. Mater. Chem. Vol. 12(2002), p.1926. [3] Zou Z.G., Mai L.Q., Chen H.Y.: J. Wuhan Univ. Tech. Mater. Sci., Vol. 16(2001), p6. Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant No.59802009, 50172036), the Science Fund for Distinguished Young Scholars of Hubei Province and the Teaching and Research Award Program for Outstanding Young Professors in Higher Education Institute, MOE, P. R. China.

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

    Scientific Electronic Library Online (English)

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

    2014-09-01

    Full Text Available En este estudio se evaluaron dos filtros anaerobios de igual configuracin en escala de laboratorio y usando cscara de coco como material de soporte, para el tratamiento de las aguas residuales del proceso de extraccin de almidn de yuca. Considerando que en el rea de estudio el inculo disponibl [...] e en cantidad suficiente es el estircol de vaca, se us este inculo solo (Reactor R1) y combinado con lodo granular en una proporcin 1:1 (Reactor R2). Se evalu la influencia del inculo sobre el desempeo de los filtros anaerobios, sobre la adaptacin 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 Retencin Hidrulico (TRH) de aproximadamente 12 horas, Carga Orgnica Volumtrica (COV) de 7.0 kg DQO/m3*d y un ndice Buffer (IB) entre 0.20 y 0.35. El incremento hasta de 50% en la Actividad Metanognica Especfica (AME) al final del arranque en ambos reactores, confirm la adecuada adaptacin 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 estircol de vaca con lodo granular mejor la produccin de metano y la eficiencia del proceso. Se encontr que la biomasa ocluida tuvo mayor actividad que la biomasa adherida, indicando que el medio de soporte favoreci el desarrollo de una mayor proporcin 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.

  8. Analysis of VoIP Traffic with Multiple Packet Transfer

    Directory of Open Access Journals (Sweden)

    Tara Chand, Vishal Srivastava

    2012-06-01

    Full Text Available Voice over Internet Protocol (VoIP is a form of voice communication. Today Wireless LANs are providing a cost effective alternative for the voice communication. Initially the wireless access protocols are not suitable for the voice communication. Subsequently, new techniques are developed for the real time voice communication. In voice communication the delay is an important factor. In this paper a new technique is proposed for the voice over IEEE 802.11 WLANs. The proposed technique is compared with Modified ICF

  9. Content Delivery System for Optimal VoD Streaming

    OpenAIRE

    Gramatikov, Sasho; Jaureguizar Núñez, Fernando; Cabrera Quesada, Julian; García Santos, Narciso

    2011-01-01

    The demand of video contents has rapidly increased in the past years as a result of the wide deployment of IPTV and the variety of services offered by the network operators. One of the services that has especially become attractive to the customers is real-time video on demand (VoD) because it offers an immediate streaming of a large variety of video contents. The price that the operators have to pay for this convenience is the increased traffic in the networks, which are becoming more conges...

  10. 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.

  11. 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 of the ...

  12. Maqueta VoIP con media gateway controllers

    OpenAIRE

    Goicoechea Bozal, Ignacio Javier

    2010-01-01

    El presente proyecto fin de carrera tiene como objeto estudiar y comprobar el funcionamiento de un protocolo VoIP basado en una arquitectura softswitch. La tecnología softswitch nace con el fin de facilitar la interconexión entre la red telefónica pública conmutada y redes basadas en paquetes. Por esta razón, las grandes compañías telefónicas son las principales usuarias de este tipo de arquitectura. Se han evaluado 3 posibles protocolos para controlar la maqueta que se desea diseñar: SGC...

  13. Comprehensive picture of VO2 from band theory

    KAUST Repository

    Zhu, Zhiyong

    2012-08-28

    The structural, electronic, and magnetic features of the metal-insulator transition from the tetragonal rutile (R) to the monoclinic (M1) phase of VO2 are well reproduced by band theory using the modified Becke-Johnson exchange potential. Based on this description, we identify a tendency for monoclinic charge ordering in the R phase due to electronic correlations as the origin of the phase transition. Whereas, the structural changes are crucial for the gap opening in the M1 phase, spin degeneracy in both phases is stabilized by correlation-induced delocalization of the V3d electrons.

  14. Synthesis, structure, luminescence properties, quantum chemistry and cytotoxic effects of two vanadium(IV) complexes with polypyrazolylborates, HB(pz)3VO(acac) and HB(3,5-Me2pz)3VO(acac)CH3CN (pz=pyrazole)

    International Nuclear Information System (INIS)

    The reaction of VO(acac)2 (acac = acetylacetonate) with NaHB(pz)3 (pz=pyrazole) or NaHB(3,5-Me2pz)3 in methanol gave vanadium(IV) complexes HB(pz)3VO(acac) (1) or HB(3,5-Me2pz)3VO(acac)CH3CN (2), respectively. The complexes 1 and 2 were characterized by elemental analysis, IR, UV-vis, 1H NMR and X-ray diffraction crystallography methods. Complex 1 crystallizes in space group P21/c, a=7.641(2), b=17.008(4), c=13.362(2) A; ?=92.092(17) deg, V=1735.5(7) A3, Z=4. Complex 2 crystallizes in space group P21/c, a=17.410(13), b=8.076(16), c=19.300(13) A; ?=101.75(5) deg, V=2657(6) A3, Z=4. X-ray structure analyses have shown that the complexes 1 and 2 are monomeric with a similar coordination environment of the vanadium atom. Luminescence properties and cytotoxic effects of the complexes are discussed. On CBRH-7919 cells, the complexes 1 and 2 caused a slight stimulation of growth at low doses (1-10 ?M) and a significant cytotoxic effect at higher doses (100-1000 ?M). The electronic structure and the bonding characters of the two complexes were analyzed with ab initio calculations

  15. VoIP Technology: Investigation of QoS and Security Issues

    Directory of Open Access Journals (Sweden)

    Amor Lazzez

    2014-06-01

    Full Text Available Voice over IP (VoIP is the technology allowing voice traffic transmission as data packets over a private or a public IP network. VoIP allows significant benefits for customers and communication services providers. The main are cost savings, rich media service, phone and service portability and mobility, and the integration with other applications. Nevertheless, the deployment of the VoIP technology encounters many challenges such as architecture complexity, interoperability problems, QoS concerns, and security issues. Due to the inability of the IP networking technology to support the stringent QoS constraints of voice traffic, and the incapability of traditional security mechanisms to adequately protect VoIP systems from recent intelligent attacks, QoS and security issues are considered as the most serious challenges for successful deployment of the VoIP technology. The aim of this paper is to carry out a deep analysis of the security issues and QoS concerns of the VoIP technology. Firstly, we present a brief overview about the VoIP technology. Then, we discuss the QoS problems encountering the deployment of the VoIP technology. The presented discussion mainly address the QoS issues related to the use of the IP networking technology, the QoS concerns related to voice clarity, and the QoS mechanisms proposed to support voice traffic QoS constraints. After that, we investigate the security issues of the VoIP technology. The presented investigation mainly address the vulnerabilities and security attacks of VoIP systems, as well as the countermeasures that should be considered to help the deployment of secured VoIP systems.

  16. Extraction Of Electronic Evidence From VoIP: Identification & Analysis Of Digital Speech

    Directory of Open Access Journals (Sweden)

    David Irwin

    2012-09-01

    Full Text Available The Voice over Internet Protocol (VoIP is increasing in popularity as a cost effective and efficient means of making telephone calls via the Internet. However, VoIP may also be an attractive method of communication to criminals as their true identity may be hidden and voice and video communications are encrypted as they are deployed across the Internet. This produces in a new set of challenges for forensic analysts compared with traditional wire-tapping of the Public Switched Telephone Network (PSTN infrastructure, which is not applicable to VoIP. Therefore, other methods of recovering electronic evidence from VoIP are required.  This research investigates the analysis and recovery of digitised human, which persists in computer memory after a VoIP call.This paper proposes a proof of concept how remnants of digitised human speech from a VoIP call may be identified within a forensic memory capture based on how the human voice is detected via a microphone and encoded to a digital format using the sound card of your personal computer. This digital format is unencrypted whist processed in Random Access Memory (RAM before it is passed to the VoIP application for encryption and  transmission over the Internet. Similarly, an incoming encrypted VoIP call is decrypted by the VoIP application and passes through RAM unencrypted in order to be played via the speaker output.A series of controlled tests were undertaken whereby RAM captures were analysed for remnants of digital speech after a VoIP audio call with known conversation. The identification and analysis of digital speech from RAM attempts to construct an automatic process for the identification and subsequent reconstruction of the audio content of a VoIP call.

  17. Synthesis and characterization of Pt/AgVO{sub 3} nanowires for degradation of atrazine using visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Malkhasian, Aramice Y.S., E-mail: amalkhasian10@gmail.com

    2015-11-15

    A hydrothermal method was used to prepare β-AgVO{sub 3} nanowire, a photo-assisted deposition (PAD) method was used to prepare Pt/β-AgVO{sub 3} nanowires. β-AgVO{sub 3} and Pt/β-AgVO{sub 3} nanowires were characterized using XRD, BET, UV–Vis spectroscopy, Pl, TEM, and XPS techniques. The results reveal that platinum was present as platinum metal and it is well dispersed on the surface of β-AgVO{sub 3} nanowire. The photocatalytic degradation of atrazine under visible light irradiation was used to measure the photocatalytic performance of the β-AgVO{sub 3} and Pt/β-AgVO{sub 3} nanowires. The photocatalytic activity of Pt/β-AgVO{sub 3} nanowires have higher photocatalytic activity than β-AgVO{sub 3} nanowire. The reason for the high photocatalytic activity of Pt/β-AgVO{sub 3} nanowires may be due to the synergic effect between Pt and β-AgVO{sub 3}. - Highlights: • Pt/β-AgVO{sub 3} nanowires were successfully prepared. • By control weight percent of Pt photocatalytic activity can be controlled. • Pt/β-AgVO{sub 3} can complete oxidation of atrazine under visible light irradiation.

  18. Mel-cepstrum-based steganalysis for VoIP steganography

    Science.gov (United States)

    Kraetzer, Christian; Dittmann, Jana

    2007-02-01

    Steganography and steganalysis in VoIP applications are important research topics as speech data is an appropriate cover to hide messages or comprehensive documents. In our paper we introduce a Mel-cepstrum based analysis known from speaker and speech recognition to perform a detection of embedded hidden messages. In particular we combine known and established audio steganalysis features with the features derived from Melcepstrum based analysis for an investigation on the improvement of the detection performance. Our main focus considers the application environment of VoIP-steganography scenarios. The evaluation of the enhanced feature space is performed for classical steganographic as well as for watermarking algorithms. With this strategy we show how general forensic approaches can detect information hiding techniques in the field of hidden communication as well as for DRM applications. For the later the detection of the presence of a potential watermark in a specific feature space can lead to new attacks or to a better design of the watermarking pattern. Following that the usefulness of Mel-cepstrum domain based features for detection is discussed in detail.

  19. Structural analysis of strained LaVO3 thin films.

    Science.gov (United States)

    Rotella, H; Copie, O; Steciuk, G; Ouerdane, H; Boullay, P; Roussel, P; Morales, M; David, A; Pautrat, A; Mercey, B; Lutterotti, L; Chateigner, D; Prellier, W

    2015-05-01

    While structure refinement is routinely achieved for simple bulk materials, the accurate structural determination still poses challenges for thin films due on the one hand to the small amount of material deposited on the thicker substrate and, on the other hand, to the intricate epitaxial relationships that substantially complicate standard x-ray diffraction analysis. Using both electron and x-ray diffraction, we analyze the crystal structure of epitaxial LaVO3 thin films grown on (1?0?0)-oriented SrTiO3. Transmission electron microscopy study reveals that the thin films are epitaxially grown on SrTiO3 and points to the presence of 90 oriented domains. The mapping of the reciprocal space obtained by high resolution x-ray diffraction permits refinement of the lattice parameters. We finally deduce that strain accommodation imposes a monoclinic structure onto the LaVO3 film. The reciprocal space maps are numerically processed and the extracted data computed to refine the atomic positions, which are compared to those obtained using precession electron diffraction tomography. PMID:25765433

  20. 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 ...

  1. Chapter 30: Crossmatching Data in the VO: BCG Line Ratios

    Science.gov (United States)

    Miller, C. J.; Krughoff, K. S.

    In this chapter, we will determine the emission line ratios of Brightest Cluster Galaxies (BCGs) in a sample drawn the Sloan Digital Sky Survey C4 galaxy cluster catalog (Miller et al. 2005). These line ratios can be used to provide some insight on whether these galaxies are star-forming or contain an Active Galactic Nucleus. We will utilize a series of VO tools: Open SkyPortal, TOPCAT and VOPlot. BCGs can be defined in different ways and are often synonymous with brightest central galaxies or even cD galaxies (galaxies with optically extended light envelopes). BCGs are the most massive galaxies and their formation and evolution are a popular and current research topic (Linden et al. 2006, Bernardi et al. 2006, Lauer et al. 2006). They have been studied for some time (Sandage 1972, Ostriker & Tremain 1975, White 1976, Thuan & Romanishin 1981, Merritt 1985, Postman and Lauer 1995, among many others). In this VO research example, our aim is to take a list of galaxies known to lie within the footprint of the SDSS, which provides us with the possibility that some of these galaxies will have measured spectra from the SDSS spectroscopic pipeline. Thus, there is some prerequisite knowledge: 1) Many bright SDSS galaxies have spectra with measured emission line properties; 2) Our catalog of Brightest Cluster Galaxies has some overlap with the SDSS footprint. Taken together, we can crossmatch our catalog to the SDSS spectroscopic galaxy data in order to extract any available emission-line information.

  2. MAXIMAL OXIGEN UPTAKE (VO2 MAX AS THE INDICATOR OF PHYSICAL WORKING CAPACITY IN SPORTSMEN

    Directory of Open Access Journals (Sweden)

    Zvezdana Rajkovaca

    2005-12-01

    Full Text Available The term “aerobic capacity” represents the sum of aerobic metabolic processes in human organism. It is the basis of the physical working capacity. Value of the maximal oxygen uptake (VO2max is the best indicator for the aerobic capacity evaluation.The purpose of this study was to check the possibility of using VO2max as the indicator of aerobic capacity in sportsmen and to check differences in VO2max values in regard to non-sportsmen.The goals were: 1.Analyses of the VO2max values in sportsmen of various sports 2. Comparison of values of sportsmen with the values of non-sportsmen.This study included 67 sportsmen (rowers, football players and judoists and 28 nonsportsmen. VO2max was measured by using a direct method.The results obtained show statistically higher VO2max values in rowers (4,52 L/min - 55,8 mL/kg/min in regard to football players (4,2 L/min – 53,6 mL/kg/min, judoists (3,58 L/min - 47,2 mL/ kg/min and non-sportsmen (3,28 L/min – 42,3 mL/kg/min. Successful rowing requires high anaerobic capacity and, therefore, high VO2max.These results show higher values of VO2max in sportsmen in regard to non-sportsmen, which is the result of training only.

  3. Selective synthesis of monazite- and zircon-type LaVO(4) nanocrystals.

    Science.gov (United States)

    Jia, Chun-Jiang; Sun, Ling-Dong; You, Li-Ping; Jiang, Xiao-Cheng; Luo, Feng; Pang, Yu-Cheng; Yan, Chun-Hua

    2005-03-01

    Pure monoclinic (m-) and tetragonal phased (t-) LaVO(4) nanocrystals could be obtained by a hydrothermal method in a controllable way with additives. It is found that chelating ligands, such as ethylenediaminetetraacetic acid [EDTA or H(4)L, where L(4-) = (CH(2)COO)(2)N(CH(2))(2)N(CH(2)COO)(2)(4-)], favor the formation of t-LaVO(4) and can induce the polymorph transformation from stable m-LaVO(4) to metastable t-LaVO(4). Further studies demonstrated the important roles of chelating ligands in this transformation process. Careful investigation over the phase transition from t- to m-LaVO(4) was also conducted with high-temperature X-ray diffraction (HTXRD) studies. The phase transition occurred at 850 degrees C, which is about 250 degrees C higher than for the bulk. The enhanced thermal stability of the nanosized metastable t-LaVO(4) may come from the small size effect. Our capability of obtaining and stabilizing t-LaVO(4) not only benefits the wider applications based on LaVO(4) due to the improved luminescent and catalytic performance but also provides a new idea in the studies of polymorph control and selective synthesis of inorganic materials. PMID:16851354

  4. Influencia de la variabilidad edafica en la produccin de biomasa del cultivo de la ua de gato uncaria tomentosa (willd d.c. en la cuenca del ro aguaytia, region Ucayali -Per

    Directory of Open Access Journals (Sweden)

    Teresa E. Mechn

    2007-01-01

    Full Text Available En Mayo 2003 se instalaron cuatro plantaciones de ua de gato Uncaria tomentosa (Willd D.C a lo largo de la Cuenca del Ro Aguaytia en Ucayali Per. Las plantas correspondieron al clon 11, propagadas in vitro, y procedentes del Instituto de Biotecnologa (IBT de la Universidad Nacional Agraria La Molina (UNALM. El estudio se bas en la determinacin de la influencia edfica en la produccin de biomasa de esta especie como cultivo. Las reas experimentales se encuentran a diferentes niveles altitudinales desde los 136 hasta los 884 msnm. En Junio 2005 se realiz 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 produccin de la biomasa del clon; siendo las ecuaciones ms 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 adaptacin de esta especie como cultivo fueron: los contenidos de fsforo (P, materia orgnica (M.O., nitrgeno (N total, saturacin de aluminio (% Al, potasio (K, magnesio (Mg y el pH

  5. Aprovechamiento de Biomasa Peletizada en el Sector Ladrillero en Bogot-Colombia: Anlisis Energtico y Ambiental Use of Pelleted Biomass in the Brick Industry in Bogota-Colombia: Energy and Environmental Analysis

    Directory of Open Access Journals (Sweden)

    Csar A Garca-Ubaque

    2013-01-01

    Full Text Available En este estudio se compara el desempeo energtico y ambiental del uso de combustibles a partir de dos tipos de biomasas peletizadas: residuos de madera, provenientes de podas y residuos de la produccin de muebles, principalmente aserrn. La biomasa proveniente de residuos de madera es uno de los materiales ms adecuados para utilizar como combustible alternativo. El sector ladrillero tiene una gran demanda energtica para sus procesos de secado y coccin y el uso de combustibles alternativos a partir de biomasa permite obtener reducciones importantes en emisiones atmosfricas y no afecta las condiciones tcnicas del proceso de produccin de ladrillos. La biomasa con mejor desempeo, tanto en las variables energticas como ambientales evaluadas, fue el aserrn.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 sector 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.

  6. Conversion efficiency of photosynthetically active radiation intercepted in biomass in stands of black wattle in Brazil / Eficiencia de conversin de la radiacin fotosintticamente activa interceptada en biomasa en rodales de acacia negra en Brasil

    Scientific Electronic Library Online (English)

    Alexandre, Behling; Carlos Roberto, Sanquetta; Ana Paula, Dalla Corte; Braulio, Caron; Augusto Arlindo, Simon; Marcos, Behling; Denise, Schmidt.

    Full Text Available El rendimiento en biomasa es una funcin de la eficiencia de conversin de radiacin fotosintticamente activa interceptada en fotoasimilados y vara, dependiendo de las condiciones en que se cultiva una planta. Este estudio cuantific la eficiencia de conversin de la radiacin solar interceptada p [...] or la biomasa fotosintticamente activa (?b) en rodales acacia negra (Acacia mearnsii). Se realiz un estudio en rodales de 1-7 aos de edad en dos sitios (para abarcar el ciclo completo de cultivo de la especie), en que se determinaron la radiacin fotosintticamente activa interceptada (PARI), el ndice de rea foliar, el coeficiente de extincin de la luz y el rendimiento de biomasa. Se propuso un sistema de ecuaciones que expres como la radiacin fotosinttica es interceptada y los asimilados se convierten. El sistema de ecuaciones estima el rendimiento de biomasa y al mismo tiempo predice la particin de la biomasa dentro del rbol. El rendimiento en biomasa de acacia negra se relacion linealmente con RFAi y la ?b de la biomasa total de acacia negra fue 0,0021 kg MJ". Abstract in english Biomass yield is a function of the conversion efficiency of photosynthetically active radiation intercepted in photoassimilates and varies depending on the conditions in which a plant is grown. Thus, this study sought to quantify the conversion efficiency of solar radiation intercepted by photosynth [...] etically active biomass (?b) in black wattle stands (Acacia mearnsii De Wild.). A study was therefore conducted in 1-7 year-old stands of the species in two sites (to span one plantation cycle), in which intercepted photosynthetically active radiation (PARi), leaf area index, light extinction coefficient and biomass yield were determined. A system of equations is proposed, therefore, as photosynthetic radiation is intercepted and assimilates are converted, the system of equations estimates biomass yield, and at the same time predicts the biomass partition within the tree. The biomass yield of black wattle was linearly related to PARi and the ?b of the total biomass of black wattle is 0.0021 kg MJ-1.

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

    International Nuclear Information System (INIS)

    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

  8. Theoretical characterization of vanadyl and VO3+ cations in gas phase

    Science.gov (United States)

    Almenia, S.; Mogren Al Mogren, M.; Ben Abdallah, D.; Linguerri, R.; Hochlaf, M.

    2016-02-01

    We investigate VO2+ and VO3+ ions theoretically. The electronic computations are performed using multi reference configuration interaction approaches in conjunction with the aug-cc-pV5Z basis set. VO2+ potential possesses a Morse-like shape instead of the common volcanic shape since both the charge retaining (V2+ + O) and charge separating (V+ + O+) dissociation channels are almost coinciding in energy. Its intense blue color is due to the A2?-X2? transition. We predict VO3+ as metastable. For bound states, we derived a set of accurate spectroscopic parameters. We estimate the adiabatic double and triple ionization energies of VO to be 22.5 eV and 50.9 eV.

  9. Wavelength-Tunable Infrared Metamaterial by Tailoring Magnetic Resonance Condition with VO2 Phase Transition

    CERN Document Server

    Wang, Hao; Wang, Liping

    2014-01-01

    In this work, we report the design of a wavelength-tunable infrared metamaterial by exciting magnetic resonance with phase transition of vanadium dioxide (VO2). Numerical simulation shows a broad absorption peak at the wavelength of 10.9 um when VO2 is a metal, but it shifts to 15.1 um when VO2 changes to dielectric phase below its phase transition temperature of 68degC. The large tunability of 38.5% in the resonance wavelength stems from the different excitation conditions of magnetic resonance assisted by plasmon in metallic VO2 but optical phonons in dielectric VO2. The physical mechanism is elucidated with the aid of electromagnetic field distribution at the resonance wavelengths. A hybrid magnetic resonance mode due to plasmon-phonon coupling is also discussed. The results here would be beneficial for active control in novel electronic, optical and thermal devices.

  10. 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.

  11. 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.

  12. 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, Hyun-Tak; Basov, D. N.

    2015-03-01

    We have demonstrated large area, low voltage, non-volatile tuning of an electrolyte-based vanadium dioxide (VO2) THz memory metasurface. Using ionic gel gating, voltage is applied to drive the insulator-to-metal transition in an underlying VO2 layer. Through application of positive and negative voltages, the metasurface resonance can be switched into the ``off'' or ``on'' state by driving VO2 into a more conductive or insulating regime, respectively. As compared to our graphene-based control devices, the longer saturation time of resonance modification in VO2-based devices suggests that this voltage-induced switching originates primarily from electrochemical effects resulting from oxygen migration across the electrolyte-VO2 interface.

  13. Selective growth of single phase VO{sub 2}(A, B, and M) polymorph thin films

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Amar; Saha, Surajit [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); NUSNNI-NanoCore, National University of Singapore, Singapore 117576 (Singapore); Rotella, Helene [NUSNNI-NanoCore, National University of Singapore, Singapore 117576 (Singapore); Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Pal, Banabir [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Kalon, Gopinadhan; Mathew, Sinu; Motapothula, Mallikarjuna; Dykas, Michal [NUSNNI-NanoCore, National University of Singapore, Singapore 117576 (Singapore); Yang, Ping [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Okunishi, Eiji [Electron Optics Division, JEOL Ltd., Tokyo 196-8558 (Japan); Sarma, D. D. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Council of Scientific and Industrial Research-Network of Institutes for Solar Energy (CSIR-NISE), New Delhi 110001 (India); Venkatesan, T., E-mail: venky@nus.edu.sg [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); NUSNNI-NanoCore, National University of Singapore, Singapore 117576 (Singapore); Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore)

    2015-02-01

    We demonstrate the growth of high quality single phase films of VO{sub 2}(A, B, and M) on SrTiO{sub 3} 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 VO{sub 2} and their electronic properties are investigated. VO{sub 2}(A) phase is insulating VO{sub 2}(B) phase is semi-metallic, and VO{sub 2}(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.

  14. 'Cation-cation' complexes of pentavalent actinides; complexes formed by NpO+2 or VO+2 with VO2+ in aqueous perchlorate solutions

    International Nuclear Information System (INIS)

    Dioxoneptunium(V) and dioxovanadium(V) ions were found to react with the oxovanadium(IV) ion in acid aqueous perchlorate solutions leading to the formation of the 'cation-cation' complexes NpVO33+ and V2O33+. The stability constants of formation for the NpVO33+ and V2O33+ complexes were found, by near IR spectrophotometry, to be anti K/GAMMA=(0.69 +- 0.12) and (0.31 +- 0.03) M-1 respectively for values of ClO4- concentration of 4.1 to 4.2 M and for values of the ionic strength ? between 6.1 and 6.2. Raman spectrometry was used to study the competition involving the VO2+ and NpO2+ ions, between the formation reactions of the complex, NpVO33+, and of the dimer, Np2O42+. For the NpVO33+ complex, the symmetrical vibration of the linear O=Np(V)=O group was found to occur at 775 cm-1 and a peak corresponding to an Nb-O-V oxygen bridge was not observed. Since a V-O-V oxygen bridge probably exists in the V2O33+ complex, and since Raman spectral evidence for a Np-O-V bridge was not observed, it was concluded that NpVO33+ and V2O33+ have different structures. (orig.)

  15. Synthesis, surface and optical properties of Ag2Cu(VO3)4 and Cu(VO3)2 vanadates

    Science.gov (United States)

    Qiao, Xuebin; Wan, Yingpeng; Li, Yuze; Qin, Lin; Seo, Hyo Jin

    2016-04-01

    Ag2Cu(VO3)4 and Cu(VO3)2 were prepared via the sol-gel chemical synthesis. The phase formation was confirmed by X-ray powder polycrystalline diffraction (XRD) measurements. The surface properties were measured with the scanning electron microscope (SEM), energy dispersive spectra (EDS), transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms. The optical properties and the band-gap structures were investigated. The vanadates have efficient optical absorption in the UV to visible wavelength region with an indirect allowed transition. Ag2Cu(VO3)4 has smaller band gap (1.85 eV) than that of Cu(VO3)2 (2.03 eV). The narrowed band gap is due to the hybridization between the Ag-4d and O-2p in the valence band. The photocatalysis was investigated by photodegradation of methylene blue (MB) solutions excited by the light with wavelength longer than 420 nm. Correspondingly Ag2Cu(VO3)4 has more efficient photocatalytic activity on MB photodegradation than that of Cu(VO3)2. The photocatalytic mechanisms were suggested according to the band positions and the trapping experiments.

  16. Microstructures and thermochromic properties of tungsten doped vanadium oxide film prepared by using VO{sub X}-W-VO{sub X} sandwich structure

    Energy Technology Data Exchange (ETDEWEB)

    Luo Zhenfei, E-mail: zhfluo@yahoo.com.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Wu Zhiming, E-mail: zmwu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Xu Xiangdong; Du Mingjun; Wang Tao; Jiang Yadong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2011-05-25

    Tungsten doped vanadium oxide (VO{sub X}) thin films were prepared by oxygen annealing VO{sub X}-W-VO{sub X} sandwich layers. X-ray photoelectron spectroscopy, X-ray diffraction and field emission scanning electron microscope were employed to characterize the compositions, crystal structures and surface morphologies, respectively. It was demonstrated that sandwich structure suppressed the crystallization of VO{sub X}, and that V{sup 5+} was reduced by diffused W atom to V{sup 4+}. The results of surface morphologies indicated that the grain arrangement of W doped vanadium dioxide film exhibited some regular patterns compared with the random grain distribution of undoped film. Electrical measurements showed that the square resistance of V{sub 2}O{sub 5} film and semiconductor-metal transition temperature of VO{sub 2}-V{sub 2}O{sub 5} film decreased obviously after W doping. In addition, thermal hysteresis loop was observed in W doped V{sub 2}O{sub 5} film with thick W middle layer. The investigation of optical properties indicated that the optical band gap of W doped V{sub 2}O{sub 5} film decreased with the increase of thickness of W middle layer, and the optical switching performance in the near-infrared range of VO{sub 2}-V{sub 2}O{sub 5} slightly weakened after W doping.

  17. EPR and UV/VIS spectroscopic investigations of VO2+ complexes and compounds formed in alkali pyrosulfates

    DEFF Research Database (Denmark)

    Rasmussen, Søren Birk; Eriksen, Kim Michael; Fehrmann, Rasmus

    2002-01-01

    fraction of the sample occupied by the cation. This indicates that spin-spin relaxation effects are the major contribution to line broadening. Combining information from UV/VIS and EPR spectra shows that the VO2+ unit in the molten salt solvent exhibits electronic properties close to aqueous solutions of V(IV).......The catalytically important molten salt-gas system M2S2O7-M2SO4-V2O5/SO2(g) (M = Na. K, Rb, Cs) has been investigated by X- and Q-band EPR spectroscopy. In order to obtain information about the V(IV) complex formation in the melts, samples rather dilute in V2O5 were quenched from the molten state...

  18. Synthesis, Crystal Structure, and Properties of the Alluaudite-Type Vanadates Ag2-xNaxMn2Fe(VO4)3.

    Science.gov (United States)

    Ben Yahia, Hamdi; Shikano, Masahiro; Tabuchi, Mitsuharu; Belharouak, Ilias

    2016-05-01

    The new members of the Ag2-xNaxMn2Fe(VO4)3 (0 ≤ x ≤ 2) solid solution were synthesized by a solid-state reaction route, and their crystal structures were determined from single-crystal X-ray diffraction data. The physical properties were characterized by Mössbauer and electrochemical impedance spectroscopies, galvanostatic cycling, and cyclic voltammetry. These materials crystallize with a monoclinic symmetry (space group C2/c), and the structure is considered to be a new member of the AA'MM'2(XO4)3 alluaudite family. The A, A', M, and X sites are fully occupied by Ag(+)/Na(+), Ag(+)/Na(+), Mn(2+), and V(5+), respectively, whereas a Mn(2+)/Fe(3+) mixture is observed in the M' site. The Mössbauer spectra confirm that iron is trivalent. The impedance measurements indicate that the silver phase is a better conductor than the sodium phase. Furthermore, these phases exhibit ionic conductivities 2 orders of magnitude higher than those of the homologous phosphates. The electrochemical tests prove that Na2Mn2Fe(VO4)3 is active as positive and negative electrodes in sodium-ion batteries. PMID:27054803

  19. Productividad interanual e interestacional de la biomasa aérea en la Chiquitanía transicional a la Amazonía (Guarayos, Bolivia

    Directory of Open Access Journals (Sweden)

    Erwin Pardo-Toledo

    2014-09-01

    Full Text Available Según investigaciones recientes, el cambio climático acentuará la estacionalidad con sequías prolongadas, lo cual repercutirá drásticamente sobre el almacenamiento de CO2 en los bosques amazónicos. Para determinar su impacto a menor escala, en el presente estudio se obtuvo los datos de densidad, altura total e incremento diamétrico mensual de árboles con DAP ≥ 10 cm en dos parcelas de 1 ha (100 x 100 m en un bosque húmedo (BH y bosque seco (BS en Kenia, Guarayos (Santa Cruz, Bolivia. Estos datos se introdujeron a ecuaciones alométricas para estimar la biomasa y luego obtener la productividad de biomasa aérea (PBA, comparándola entre un año húmedo (2009 y uno seco (2010; asimismo se contrastó entre sus estaciones (húmeda, semiseca, seca, semihúmeda, además de analizar su relación con la precipitación pluvial y temperatura. La PBA interanual fue significativamente mayor en el año húmedo (BH = 40.16 kg/árbol/año; BS = 24.21 kg/árbol/año respecto al año seco (BH = 35.97 kg/árbol/año; BS = 17.71 kg/árbol/año (p < 0.05, mientras que la PBA interestacional fue mayor en la estación húmeda/2009 y la menor en la seca/2010, un escenario observado en ambos tipos de bosque. En cuanto a la relación de los factores climáticos con la PBA estacional, se evidenció que la precipitación pluvial tuvo una alta relación con la productividad (BH: r s = 0.91; p < 0.05; (BS: r s= 0.88; p < 0.05. Con lo que se deduce que los periodos con sequías prolongadas afectan significativamente la productividad de biomasa aérea, afirmándose que el clima juega un rol fundamental en la dinámica de estos bosques.

  20. Efecto de la temperatura y el pH en la producción de biomasa de Azospirillum brasilense C16 aislada de pasto guinea

    Directory of Open Access Journals (Sweden)

    F Romero-Perdomo

    2015-09-01

    Full Text Available El objetivo del estudio fue evaluar el efecto de la temperatura y el pH en la viabilidad celular de la cepa Azospirillum brasilense C16. Se estudiaron cinco temperaturas (entre 28 y 36°C y cinco pH (de 4,5 a 8,5. El efecto de la temperatura se evaluó mediante la medición del crecimiento radial (mm de la cepa, sobre un papel de filtro en medio batata. En el caso del pH se utilizó un fermentador de tanque agitado -con una configuración tipo Rushton- para cuantificar la velocidad de crecimiento, la producción de biomasa y el tiempo de duplicación de la cepa; las condiciones de fermentación fueron: 400 rpm, 1 Lpm y 30°C, durante 24 horas. El pH y la temperatura influyeron significativamente (p < 0,05 en la producción de A. brasilense C16. La temperatura de 30°C fue la más favorable para que se multiplicara la cepa, con 23,21 mm de crecimiento radial; mientras que la mayor o igual a 34°C inhibió su crecimiento. Los mejores resultados se obtuvieron con un pH de 6,8, con diferencias significativas (p < 0,05 respecto al resto. Con esta condición se obtuvieron los valores más altos de velocidad de crecimiento (1,79 h-1 y producción de biomasa (8,65 log10 UFC mL-1, y el valor más bajo del tiempo de duplicación (1,09 h-1. Estos resultados poseen aplicabilidad biotecnológica, y son de gran importancia en el momento de definir y controlar las condiciones de producción masiva de biomasa de A. brasilense C16 para futuras formulaciones como biofertilizante en diversos cultivos de interés en Colombia.

  1. VO(2+)-hydroxyapatite complexes as models for vanadyl coordination to phosphate in bone.

    Science.gov (United States)

    Dikanov, Sergei A; Liboiron, Barry D; Orvig, Chris

    2013-09-01

    We describe a 1D and 2D ESEEM investigation of VO(2+) adsorbed on hydroxyapatite (HA) at different concentrations and compare with VO(2+)-triphosphate (TPH) complexes studied previously in detail, in an effort to provide more insight into the structure of VO(2+)coordination in bone. Structures of this interaction are important because of the role of bone in the long-term storage of administered vanadium, and the likely role of bone in the steady-state release of vanadium leading to the chronic insulin-enhancing anti-diabetic effects of vanadyl complexes. Three similar sets of cross-peaks from phosphorus nuclei observed in the (31)P HYSCORE spectra of VO(2+)-HA, VO(2+)-TPH, and VO(2+)-bone suggest a common tridentate binding motif for triphosphate moieties to the vanadyl ion. The similarities between the systems present the possibility that in vivo vanadyl coordination in bone is relatively uniform. Experiments with HA samples containing different amounts of adsorbed VO(2+) demonstrate additional peculiarities of the ion-adsorbent interaction which can be expected in vivo. HYSCORE spectra of HA samples show varying relative intensities of (31)P lines from phosphate ligands and (1)H lines, especially lines from protons of coordinated water molecules. This result suggests that the number of equatorial phosphate ligands in HA could be different depending on the water content of the sample and the VO(2+) concentration; complexes of different structure probably contribute to the spectra of VO(2+)-HA. Similar behavior can be also expected in vivo during VO(2+) accumulation in bones. PMID:24829511

  2. 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 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.

  3. TERTIARY EDUCATION IN THE KNOWLEDGE-BASED SOCIETY / Terciárne vzdelávanie vo vedomostnej spoločnosti

    OpenAIRE

    Poláková Helena; Plavčan Peter

    2008-01-01

    The statement describes basic knowledge focused on the tertiary education in the knowledge-based society with positive and negative implications of transnational education.V príspevku sa uvádzajú základné poznatky o terciárnom vzdelávaní vo vedomostnej spoločnosti s osobitným zreteľom na pozitívne a negatívne dôsledky transnárodného vzdelávania.

  4. Ultrazvučno vođena sklerozacija pjenom – najjednostavnija, najmanje invazivna i najjeftinija metoda liječenja proširenih vena

    OpenAIRE

    Krnić, Anton

    2015-01-01

    Cilj ovoga rada je prikazati naša iskustva i mišljenja vezano za liječenje proširenih vena upotrebom ultrazvučno vođene sklerozacije pjenom (engl. ultrasound guided foam sclerotherapy, UGFS). U studiju smo uključili 81 bolesnika: 54 s insuficijentnim površinskim venama glavnog stabla u jednoj nozi i 27 bolesnika kod kojih su bile zahvaćene obje noge. U 68 nogu dijagnosticirali smo insuficijenciju vene safene magne (lat. vena saphena magna), u 18 vene safene parve (lat. vena saphena parva), u ...

  5. A cost-effective method to fabricate VO2 (M) nanoparticles and films with excellent thermochromic properties

    International Nuclear Information System (INIS)

    Highlights: • Via solvent–thermal and pyrolysis method, VO2 (M) powder was synthesized in air. • Aiding by grinding, VO2 (M) nanoparticles with the size of 22 nm were obtained. • The VO2 films show great thermochromic properties with Tlum = 62.1% and ΔTsol = 12.4%. • The haze is down to 1.9%, which is superior with films prepared by other methods. - Abstract: In this paper, high crystallinity and pure phase VO2 (M) powder is synthesized by a novel and facile method. Aiding by additional manual grinding and etching process, 22 nm high-quality VO2 (M) nanoparticles can be obtained. The structure and properties of the VO2 (M) particles were characterized by X-ray diffraction analysis, transmission electron microscopy, differential scanning calorimetry and UV–vis–NIR spectrophotometer. After mixing VO2 (M) nanoparticles with transparent polymer, thin films prepared by grinded VO2 nanoparticles show excellent thermochromic properties. The solar modulation ability is up to 12.4% with luminous transmittance of 62.7%. Moreover, The haze of films prepared by grinded VO2 (M) nanoparticles is down to 1.9%, which is far less than that of films prepared by original VO2 (Haze = 8.5%) and etched VO2 particles (Haze = 4.6%). Dramatical improvement of thermochromic property and definition indicate that it is a promising method to prepare large-scale VO2 nanoparticles and cost-effective smart window

  6. NEZDRAVA PREHRANA: DIJETALNE INTERVENCIJE PROMOCIJE ZDRAVLJA NA RADNOM MJESTU

    OpenAIRE

    Pranji?, Nurka; Kreitmayer, Sanda; Beganli?, Azijada; Trumi?, Edisa; Sarajli?, Selvedina; Softi?, Albina

    2013-01-01

    Radno mjesto je centralno podru?je utjecaja na prehrambeno ponaanje. U radu se analiziraju nezdravi na?ini prehrane u vezi sa u?inkovito?u dijetalnih intervencija promocije zdravlja. Daje se kratak pregled odgovaraju?ih teorijskih okvira za dizajn interventne procjene i upravljanja prema primjerima prethodnih istraivanja. Publikovani rezultati prethodnih istraivanja potvr?uju da su na radnom mjestu dijetalne intervencije obi?no u?inkovite, posebno dijetalne ntervencije vo?em i povr?em. Ma...

  7. Chloroform fumigation-extraction labile C pool (microbial biomass C "plus" shows high correlation to microbial biomass C in Argentinian and Brazilian soils Alta correlacin entre el "pool" de carbono lbil por fumigacin con cloroformo-extraccin (carbono de biomasa microbiana plus y carbono de biomasa microbiana en suelos de Argentina y Brasil

    Directory of Open Access Journals (Sweden)

    Helvcio De-Polli

    2007-07-01

    Full Text Available Chloroform fumigation-incubation and chloroform fumigation-extraction approaches have significantly contributed to assess soil microbial biomass. Some controversy is found in the literature about the suggestion to calculate microbial biomass carbon (MBC without the subtraction of the un-fumigated control, in opposition to the originally proposed method that requires such subtraction. Some authors consider the non-subtraction proceeding as a more robust method. Nevertheless, values obtained without subtraction of a control include other labile organic fractions of soil carbon besides microbial biomass. Therefore, due to the usefulness of this measurement we consider more appropriate to call it as chloroform-fumigation labile C pool or microbial biomass carbon "plus" (MBC PLUS. We used a vast series of data from soils of Argentina and Brazil under different management situations to verify whether MBC correlates to MBC PLUS. There was a significant statistical correlation between values of MBC obtained by fumigation-extraction method and the corresponding MBC PLUS. The MBC PLUS performed as well as MBC as an indicator to differentiate soil managements and their impact on soil quality.Los mtodos de fumigacin-incubacin y fumigacin extraccin han contribuido significativamente a las determinaciones de biomasa microbiana del suelo. En la literatura se encuentran algunas controversias acerca de la sugerencia de calcular el carbono de biomasa microbiana (CBM sin la sustraccin del control no fumigado, en oposicin a las metodologas tradicionales que requieren de dicha sustraccin. Algunos autores mencionan que el hecho de no realizar la sustraccin hace al procedimiento ms robusto. Sin embargo, los valores obtenidos sin la sustraccin del control incluyen otras fracciones lbiles del carbono, adems de la biomasa microbiana. Debido a lo til que resulta esta medida consideramos adecuado llamarla "pool" de carbono lbil por fumigacin con cloroformo o carbono de biomasa microbiana "plus" (CBM PLUS. Usamos una amplia serie de datos de suelos de Argentina y Brasil bajo diferentes situaciones de manejo para verificar si el CBM correlaciona con el CBM PLUS. Hubo una correlacin estadsticamente significativa entre los valores de CBM obtenidos por el mtodo de fumigacin-extraccin y los correspondientes a CBM PLUS. Este se vislumbra, al igual que el CBM, como un indicador para diferenciar situaciones de manejo de suelos y el impacto sobre su calidad.

  8. Profesní etika a právo pacienta na soukromí

    Czech Academy of Sciences Publication Activity Database

    Drozenová, Wendy

    Prešov : Filozofická fakulta Prešovskej univerzity v Prešove, 2012 - (Gluchman, V.), s. 96-109 ISBN 978-80-555-0674-6 Institutional support: RVO:67985955 Keywords : professional ethics * patient's right of privacy * Jacintha Saldanha Subject RIV: AA - Philosophy ; Religion

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

    OpenAIRE

    Pardo Luis C

    2006-01-01

    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 P...

  10. PERSPECTIVAS DE OBTENCIN DE ENERGA RENOVABLE DE LA BIOMASA DEL ESTIRCOL DEL GANADO LECHERO EN LA REGIN CENTRO-SUR DE CHIHUAHUA

    Directory of Open Access Journals (Sweden)

    Bertha Alicia Rivas Lucero

    2012-01-01

    Full Text Available Actualmente casi la totalidad de la energa es proporcionada por fuentes fsiles que incrementan las emisiones de gases invernadero contribuyendo al calentamiento global. Estas emisiones se pueden reducir con el uso de energa renovable producida a travs de la biomasa como el estircol del ganado. El estircol es materia prima para la produccin de electricidad y energa trmica. La digestin anaerbica de los desechos puede reducir las emisiones por la captura de metano, un gas invernadero producido por los desechos en instalaciones a pequea y gran escala. La regin Centro-Sur del estado de Chihuahua tiene potencial para la produccin de energa renovable a partir de la biomasa como son los desechos de aproximadamente 58,000 cabezas de ganado, valorndose una produccin diaria de 2,900 m3 de excretas y 10,000 m3 de aguas residuales que pueden ocasionar problemas ambientales. La produccin de biogs calculada fue de 1.73 m3 de biogs/vaca/da, estimndose una produccin total de biogs en la regin de 25,717,352 m3/ao y 50,722,754 kw-h/ao ahorrndose hasta $45,143 millones de pesos en energa elctrica. Se estiman reducciones de hasta 361,843 Ton-Eq de CO2. Se proponen tecnologas a pequea y gran escala. El desarrollo de tecnologas de energa renovable abre la oportunidad para que los desechos generen ingresos adicionales por la produccin de energa elctrica o energa trmica, reduciendo problemas ambientales pudiendo hacer factible la adopcin tecnolgica a pequea y gran escala por los productores.

  11. REMOCIÓN DE PLOMO Y NÍQUEL EN SOLUCIONES ACUOSAS USANDO BIOMASAS LIGNOCELULÓSICAS: UNA REVISIÓN

    Directory of Open Access Journals (Sweden)

    Edgar Quiñones

    2013-12-01

    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 obtenido 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.

  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. Reservorios de biomasa aérea y de carbono en los manglares del golfo de Urabá (Caribe colombiano

    Directory of Open Access Journals (Sweden)

    Juan F Blanco-Libreros

    2015-12-01

    Full Text Available Los manglares son los principales reservorios de biomasa aérea (BA y carbono (C sobre el suelo entre los ecosistemas marino-costeros tropicales. A partir de datos estructurales de campo y de ecuaciones alométricas publicadas, se estiman los reservorios de BA y C en la vegetación de las cuatro áreas de manglar más extensas del golfo de Urabá. Los manglares del delta del río Atrato mostraron los mayores reservorios de BA y C (165 y 83 t/ha, respectivamente concentrados en árboles de Rhizophora mangle, al igual que los de la ensenada de Rionegro (115 y 58 t/ha, respectivamente. En el costado suroriental del Golfo, los mayores valores se obtuvieron en los manglares de Puerto César-Punta Coquito (85 y 43 t/ha, respectivamente, y por último los de Turbo (76 y 38 t C/ha, respectivamente, ambos dominados por Avicennia germinans. En Turbo predominaron árboles de R. mangle y Laguncularia racemosa de diámetros < 5 cm, reflejo de la fuerte intervención antrópica y los reservorios de BA y C son menores que los de Puerto César-Punta Coquito, más alejado de la cabecera urbana. Los reservorios de biomasa de los manglares del Golfo se encuentran dentro del rango observado en todo el mundo, pero los del delta del río Atrato se acercan más al límite superior registrado. Los manglares mejor conservados del golfo de Urabá son reservorios importantes de C en la BA. La magnitud del reservorio está inversamente relacionada con la distancia a los dos principales centros poblados.

  14. 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.

  15. A structured approach to VO reconfigurations through Policies

    CERN Document Server

    Reiff-Marganiec, Stephan

    2012-01-01

    One of the strength of Virtual Organisations is their ability to dynamically and rapidly adapt in response to changing environmental conditions. Dynamic adaptability has been studied in other system areas as well and system management through policies has crystallized itself as a very prominent solution in system and network administration. However, these areas are often concerned with very low-level technical aspects. Previous work on the APPEL policy language has been aimed at dynamically adapting system behaviour to satisfy end-user demands and - as part of STPOWLA - APPEL was used to adapt workflow instances at runtime. In this paper we explore how the ideas of APPEL and STPOWLA can be extended from workflows to the wider scope of Virtual Organisations. We will use a Travel Booking VO as example.

  16. 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.

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

    Directory of Open Access Journals (Sweden)

    Magalis Zabala

    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 agrícolas 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.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 associated 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.

  18. Structural, photophysical and photocatalytic properties of novel Bi2AlVO7

    International Nuclear Information System (INIS)

    Bi2AlVO7 was prepared by solid-state reaction technique for the first time and the structural and photocatalytic properties of Bi2AlVO7 and Bi2InTaO7 were investigated. The results showed that Bi2AlVO7 crystallized in the tetragonal crystal system with space group I4/mmm. In addition, the band gaps of Bi2AlVO7 and Bi2InTaO7 were estimated to be about 2.06 and 2.81 eV. The photocatalytic degradation of aqueous methylene blue (MB) dye with Bi2AlVO7 or Bi2InTaO7 as catalyst was investigated under visible light irradiation. Bi2AlVO7 showed higher photocatalytic activity compared with Bi2InTaO7 for photocatalytic degradation of MB under visible light irradiation. Complete removal of aqueous MB dye was realized after visible light irradiation for 160 min with Bi2AlVO7 as the photocatalyst. The reduction of the total organic carbon (TOC) and the formation of inorganic products, SO42- and NO3- revealed the continuous mineralization of aqueous MB dye during the photocatalytic process. The possible photocatalytic degradation pathway of aqueous MB dye was revealed under visible light irradiation.

  19. Handover Management for VoWLAN Based on Estimation of AP Queue Length and Frame Retries

    Science.gov (United States)

    Niswar, Muhammad; Kashihara, Shigeru; Tsukamoto, Kazuya; Kadobayashi, Youki; Yamaguchi, Suguru

    Switching a communication path from one Access Point (AP) to another in inter-domain WLANs is a critical challenge for delay-sensitive applications such as Voice over IP (VoIP) because communication quality during handover (HO) is more likely to be deteriorated. To maintain VoIP quality during HO, we need to solve many problems. In particular, in bi-directional communication such as VoIP, an AP becomes a bottleneck with the increase of VoIP calls. As a result, packets queued in the AP buffer may experience a large queuing delay or packet losses due to increase in queue length or buffer overflow, thereby causing the degradation of VoIP quality for the Mobile Nodes (MNs) side. To avoid this degradation, MNs need to appropriately and autonomously execute HO in response to the change in wireless network condition, i.e., the deterioration of wireless link quality and the congestion state at the AP. In this paper, we propose an HO decision strategy considering frame retries, AP queue length, and transmission rate at an MN for maintaining VoIP quality during HO. Through simulation experiments, we then show that our proposed method can maintain VoIP quality during HO by properly detecting the wireless network condition.

  20. The heart rate VO2 relationship of aerobic dance: a comparison of target heart rate methods.

    Science.gov (United States)

    Scharff-Olson, M; Williford, H N; Smith, F H

    1992-12-01

    The purpose of this study was to examine the relationship between heart rate (HR) and oxygen consumption (VO2) for aerobic dance exercise. Therefore, eleven females completed 20 minutes of aerobic dance with continuous monitoring of HR and VO2. These physiological responses were analyzed with correlation/regression techniques. The results showed that for aerobic dance to produce a response in excess of 50% of VO2 max, the target HR must be approximately 80% of the age-predicted HR max or greater. In contrast, previously reported data for treadmill running shows that 50% of VO2 max is achieved at approximately 65% of age-predicted HR max in females. The maximum heart rate reserve (Karvonen) method was also found to underestimate the actual VO2 of AD. With the Karvonen method, the target heart rate must approximate 65% of maximum HR reserve in order to elicit a VO2 response which is representative of 50% of VO2 max. These data support recent research which illustrates that target heart rate prescriptions derived from treadmill testing may fail to accurately place AD participants in the recommended training zone. PMID:1293420

  1. Terbium-Doped VO2 Thin Films: Reduced Phase Transition Temperature and Largely Enhanced Luminous Transmittance.

    Science.gov (United States)

    Wang, Ning; Duchamp, Martial; Dunin-Borkowski, Rafal E; Liu, Shiyu; Zeng, XianTing; Cao, Xun; Long, Yi

    2016-01-26

    Vanadium dioxide (VO2) is a well-known thermochromic material with large IR modulating ability, promising for energy-saving smart windows. The main drawbacks of VO2 are its high phase transition temperature (τc = 68 °C), low luminous transmission (Tlum), and weak solar modulating ability (ΔTsol). In this paper, the terbium cation (Tb(3+)) doping was first reported to reduce τc and increase Tlum of VO2 thin films. Compared with pristine VO2, 2 at. % doping level gives both enhanced Tlum and ΔTsol from 45.8% to 54.0% and 7.7% to 8.3%, respectively. The Tlum increases with continuous Tb(3+) doping and reaches 79.4% at 6 at. % doping level, representing ∼73.4% relative increment compared with pure VO2. This has surpassed the best reported doped VO2 thin films. The enhanced thermochromic properties is meaningful for smart window applications of VO2 materials. PMID:26729057

  2. Structure and stability of monazite- and zircon-type LaVO4 under hydrostatic pressure

    Science.gov (United States)

    Cheng, Xuerui; Guo, Dongjie; Feng, Shiquan; Yang, Kun; Wang, Yongqiang; Ren, Yufen; Song, Yang

    2015-11-01

    Pure monazite (m)- and zircon (t)-type LaVO4 and LaVO4:Eu3+ were successfully synthesized by a hydrothermal method. The high pressure behavior of m- and t-LaVO4 nanoparticles has been investigated using Raman scattering techniques at room temperature. Raman measurements reveal a slight change for m-LaVO4 at 11.2 GPa because of an isostructural phase transition. However, striking changes in Raman spectra indicate a pressure-induced irreversible phase transition from the zircon to monazite structure for t-LaVO4 at around 5.9 GPa. The evolution of the luminescence spectra of t-LaVO4:Eu3+ has also been studied during the pressure-induced phase transition. It is observed that pressure has a great influence on the fluorescence intensity and the energy levels, which allows a more in-depth understanding of the nature of the pressure-induced phase transition for t-LaVO4. This result further confirms the conclusion that zircon-type RVO4 compounds with larger rare-earth cations will experience zircon to monazite phase transition.

  3. Preparation and characterization of fly ash cenospheres supported CuO–BiVO4 heterojunction composite

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Novel CuO–BiVO4/FACs heterojunction composites have been synthesized. • CuO–BiVO4 are loaded on the surface of lightweight hollow microspheres. • The CuO–BiVO4/FACs exhibit enhanced absorption in the visible light region. • The CuO–BiVO4/FACs show efficient photocatalytic activities. • The composites are floatable and can be recovered easily. - Abstract: Novel fly ash cenospheres supported CuO–BiVO4 heterojunction composites (CuO–BiVO4/FACs) were prepared by modified metalorganic decomposition and impregnation methods. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectra (XPS), and UV–vis diffused reflectance spectroscopy (DRS) techniques. The XPS and SEM analyses indicated that Cu was present as CuO dispersed on the surface of BiVO4. The DRS spectra revealed that the composites had improved optical adsorption in the visible light region, and the composites exhibited enhanced photocatalytic activity for methylene blue (MB) degradation under visible light irradiation. It was found that the 5 wt% CuO-loaded composite showed the highest photocatalytic activity for MB dye wastewater treatment. FACs, a by-product generated in coal-firing power plants, were used as a low cost support which favored phase separation after the reaction owing to their low density

  4. The VO-Dance web application at the IA2 data center

    Science.gov (United States)

    Molinaro, Marco; Knapic, Cristina; Smareglia, Riccardo

    2012-09-01

    Italian center for Astronomical Archives (IA2, http://ia2.oats.inaf.it) is a national infrastructure project of the Italian National Institute for Astrophysics (Istituto Nazionale di AstroFisica, INAF) that provides services for the astronomical community. Besides data hosting for the Large Binocular Telescope (LBT) Corporation, the Galileo National Telescope (Telescopio Nazionale Galileo, TNG) Consortium and other telescopes and instruments, IA2 offers proprietary and public data access through user portals (both developed and mirrored) and deploys resources complying the Virtual Observatory (VO) standards. Archiving systems and web interfaces are developed to be extremely flexible about adding new instruments from other telescopes. VO resources publishing, along with data access portals, implements the International Virtual Observatory Alliance (IVOA) protocols providing astronomers with new ways of analyzing data. Given the large variety of data flavours and IVOA standards, the need for tools to easily accomplish data ingestion and data publishing arises. This paper describes the VO-Dance tool, that IA2 started developing to address VO resources publishing in a dynamical way from already existent database tables or views. The tool consists in a Java web application, potentially DBMS and platform independent, that stores internally the services' metadata and information, exposes restful endpoints to accept VO queries for these services and dynamically translates calls to these endpoints to SQL queries coherent with the published table or view. In response to the call VO-Dance translates back the database answer in a VO compliant way.

  5. Specific heat of hole-doped vanadates: Y1?xCaxVO3, Pr1-xCaxVO3 and Nd1?xSrxVO3

    International Nuclear Information System (INIS)

    We have investigated the specific heat of hole-doped vanadium oxides Y1?xCaxVO3 (0 ? x ? 0.11), Pr1?xCaxVO3 (0 ? x ? 0.3) and Nd1?xSrxVO3 (0 ? x ? 0.2) probably for the first time by applying the Modified Rigid ion model (MRIM). The results obtained on temperature dependent (1 K ? T ? 300 K) specific heat are in reasonably good agreement with the experimental data. The impact of lattice distortions on the elastic and thermal properties of the present Mott insulators is portrayed by an atomistic approach. The scope of further improvement in the present model has also been discussed. - Highlights: Specific heat increases with decreasing doping level and increase in temperature. Effect of lattice distortions on bulk modulus and thermal properties is presented. MRIM has successfully predicted the cohesive properties of Ca/Sr-doped RVO3

  6. 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%.

  7. 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 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

  8. PRODUCCIÓN DE LA MACRÓFITA ACUÁTICA Lemna perpusilla UTILIZANDO AGUA RESIDUAL DE UNA INSTALACIÓN PORCINA, CON PROPÓSITOS PARA PRODUCCIÓN DE BIOMASA PARA ACUACULTURA

    Directory of Open Access Journals (Sweden)

    Pablos Reyes DP

    2011-01-01

    Full Text Available Una problemática ambiental impor- tante en instalaciones porcinas es la producción de excretas con alta concentración de nutrientes y su deposición en el ecosistema. Una alternativa para la biorremediación de dicha problemática es utilizar las excretas para la producción de plantas acuáticas que tengan una alta tasa de captación de nutrientes, tal como Lemna perpusilla. En el presente estudio se desarrollaron dos experimentos con el objetivo de estudiar el efecto de la época del año y el tiempo de cosecha sobre la biomasa, composición química y el rendimiento de nutrientes. En el experimento I (enero a abril se utilizó una dosis de fertilización de 20 Lm-2 por cada 20 días y se manejó una densidad de siembra de 200 gm-2, realizando cosechas cada 10 días. Mientras que en el experimento II (mayo a ju- nio se utilizó la misma dosis de fertilización y densidad de siembra, pero cosechando cada seis días. Durante el desarrollo experimental (enero-junio Lemna perpusilla presentó bajo contenido de materia seca (6.87 a 8.87% y fi- bra (11.67 a 12.89%, pero alto contenido de proteína (26.02 a 27.41%. Se determinó que la época y tiempo de cosecha afectan significati- vamente la cosecha total, composición química y rendimiento de nutrientes. Las variables cli- máticas que más influyeron sobre la cosecha total fueron las horas luz y precipitación. Mien- tras que el rendimiento en nutrientes es princi- palmente afectada por la temperatura, hume- dad relativa, horas luz y precipitación.

  9. 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.

  10. Study on Thermochromic VO2 Films Grown on ZnO-Coated Glass Substrates for Smart Windows

    Science.gov (United States)

    Kato, Kazuhiro; Song, Pung Keun; Odaka, Hidehumi; Shigesato, Yuzo

    2003-10-01

    Vanadium dioxide (VO2) is one of the most attractive thermochromic materials, which show large changes in optical and electrical properties at the transition temperature (Tt) close to the atmospheric temperature (approximately 340 K). We already reported for VO2 deposition by rf magnetron sputtering using V2O3 or V2O5 targets that VO2 films thicker than 400 nm showed high thermochromic performance, whereas the VO2 films thinner than 200 nm did not show such performance because of their poor crystallinity and off-stoichiometry. In this study, very thin thermochromic VO2 films with thicknesses of about 50 nm were successfully deposited using highly -preferred oriented ZnO polycrystalline films as a buffer layer between the VO2 film and glass substrate (VO2/ZnO/glass) because of the heteroepitaxial growth of VO2 polycrystalline films. W-doped VO2 films were also deposited on the ZnO-coated glass substrates (ZnO/glass) by cosputtering. It was confirmed that W doping for thin VO2 films deposited on the ZnO/glass can decrease Tt systematically. Such very thin VO2 films should have high potential for application in smart windows.

  11. VO2+-hydroxyapatite complexes as models for vanadyl coordination to phosphate in bone

    OpenAIRE

    Dikanov, Sergei A.; Liboiron, Barry D.; Orvig, Chris

    2013-01-01

    We describe a 1D and 2D ESEEM investigation of VO2+ adsorbed on hydroxyapatite (HA) at different concentrations and compare with VO2+-triphosphate (TPH) complexes studied previously in detail, in an effort to provide more insight into the structure of VO2+coordination in bone. Structures of this interaction are important because of the role of bone in the long-term storage of administered vanadium, and the likely role of bone in the steady-state release of vanadium leading to the chronic insu...

  12. Improved E-model for Monitoring Quality of Multi-Party VoIP communications

    OpenAIRE

    Adel, Mohamed; Assem, Haytham; Jennings, Brendan; Malone, David; Dunne, Jonathan; O'Sullivan, Pat

    2013-01-01

    Maintaining good Quality-of-Experience (QoE) is crucial for Voice-over-IP (VoIP) applications, particularly those operating across the public Internet. Accurate online estimation of QoE as perceived by end users allows VoIP applications take steps to improve QoE when it falls below acceptable levels. ITU-T recommendation G.107 introduced the E-model, which provides a means to assess QoE levels for two-party VoIP sessions. In this paper we provide an analysis of the accura...

  13. Research on Channel-Multiplexed Home Intercom System Based on VoIP

    OpenAIRE

    Shuixiu Li; Baochen Jiang; Zhiqiang Yang; Fuyun Song

    2014-01-01

    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 ...

  14. VoIP Session Capacity Expansion with Packet Transmission Suppression Control in Wireless LAN

    Science.gov (United States)

    Morioka, Yasufumi; Higashino, Takeshi; Tsukamoto, Katsutoshi; Komaki, Shozo

    This paper proposes a VoIP (Voice over Internet Protocol) session capacity expansion method that uses periodic packet transmission suppression control for wireless LANs. The proposed method expands the VoIP session capacity of an AP without critically degrading the QoS (Quality of Service) of all stations. Simulation results show the proposed method with 0.5% packet suppression control on each station expands a VoIP session capacity by up to 5% compared to a legacy method while satisfying required QoS for all stations.

  15. Labeled VoIP Data-set for Intrusion Detection Evaluation

    OpenAIRE

    Nassar, Mohamed; Radu, State; Festor, Olivier

    2010-01-01

    VoIP has become a major application of multimedia communications over IP. Many initiatives around the world focus on the detection of attacks against VoIP services and infrastructures. Because of the lack of a common labeled data-set similarly to what is available in TCP/IP network-based intrusion detection, their results can not be compared. VoIP providers are not able to contribute their data because of user privacy agreements. In this paper, we propose a framework for customizing and gener...

  16. Performance Analysis of Statistical Distributions for VoIP over WiMAX Access Networks

    Directory of Open Access Journals (Sweden)

    Gysberth Maurits Wattimena

    2013-04-01

    Full Text Available Statistical distributions are used to represent behavior of real VoIP traffic. This paper investigates the performance of VoIP traffic over WiMAX networks by examining statistical comparison of interarrival time distribution. The parameters are used to analyze the Quality of Service (QoS, like delay, jitter, throughput with respect to Voice Activity Detection (VAD or Silence Detection (SD in voice codec G.729. The simulation result indicates that the pareto distribution in interarrival time has a significant impact on the performance of VoIP in WiMAX network.

  17. Study on the QoE for VoIP Networks

    OpenAIRE

    Weiwei Zhang; Yongyu Chang; Yitong Liu; Atif Hameed; Yuan Tian

    2014-01-01

    In recent years, people are recognizing that the quality in VoIP application should be evaluated according to the QoE (Quality of Experience). The main goal of this paper is to analyze the different factors on the impact of voice quality for VoIP networks. Our contributions are thus threefold: First, we establish a new VoIP simulation platform. The network simulation software is WANem, the voice communication protocol is implemented by Open Phone. This simulation system is more ‘real&rs...

  18. A Voice Priority Queue (VPQ) Fair Scheduler for the VoIP over WLANs

    OpenAIRE

    Kashif Nisar; Abas Md Said; Halabi Hasbullah

    2011-01-01

    Transmission of VoIP over packet switching networks is one of the rapidly emerging real-time Internet Protocol. The real-time application of the Voice over Internet Protocol (VoIP) is growing rapidly for it is more flexible than the traditional Public Switched Telephone Networks systems (PSTN). Meanwhile, the VoIP deployment on Wireless Local Area Networks (WLANs), which is based on IEEE 802.11 standards, is increasing. Currently, many schedulers have been introduced such as Weighted Fair Que...

  19. Raman study of phonon modes in ErVO4 single crystals

    Science.gov (United States)

    Guedes, I.; Hirano, Y.; Grimsditch, M.; Wakabayashi, N.; Loong, C.-K.; Boatner, L. A.

    2001-08-01

    The phonon modes of a pure ErVO4 crystal were determined at room temperature using Raman scattering methods, and the observed frequencies were assigned according to group theory in terms of the internal modes of the VO43- ions and the external modes of the Er(VO4) lattice. The assignments of the phonon modes match well with the overall phonon systematics of the rare-earth orthovanadate series, and the results presented here reinforce the general trend of bonding strength in the zircon series of RVO4, RAsO4, and RPO4 materials.

  20. TRANSPORTE DE VOZ (VoIP SOBRE REDES IPv4 e IPv6

    Directory of Open Access Journals (Sweden)

    Fausto Alexander Gamboa

    2012-05-01

    Full Text Available El presente artículo tiene como finalidad evaluar el comportamiento de la VoIP en redes IPv6 y compararlo con IPv4, de igual manera presentar las arquitecturas que la soportan. Con el fin de que los resultados sean los más cercanos a la realidad, el artículo no solo se soporta en simulaciones si no en implementaciones reales. Dentro de las conclusiones más sobresalientes se encontró que la VoIP6 presenta mejor rendimiento ante el Jitter y el retardo que VoIPv4.

  1. User Access Control and Authentication System for VoIP Service in Mobile Communication Environments

    OpenAIRE

    Ho-Kyung Yang; Jeong-Kyung Moon; Cheol-Rim Choi; Hwang-Bin Ryou

    2014-01-01

    VoIP, which is used to transmit voice data on the Internet, is being welcomed as a replacement for the PSTN. In VoIP, voice data are converted to IP data and transmitted in an ordinary IP network. As a result, it is less expensive than the ordinary telephone network and has excellent scalability. With the increasing demand for VoIP services, problems are also occurring, namely, security vulnerabilities and degraded service quality. To address these issues, in this paper an AA (Attribute Autho...

  2. Probing electronic state at atomic scale on the surface of SrVO3 film

    Science.gov (United States)

    Okada, Yoshinori; Shimizu, Ryota; Shiraki, Susumu; Hitosugi, Taro

    2014-03-01

    Probing electronic structure of atomically well controlled surface of Perovskite-type 3d transition-metal oxides have been attracting much interest because of their intriguing emergent physical properties by heterostructure engineering. In this study, we have especially focused on SrVO3, where importance of correlation effects has been considered. We successfully obtained atomically flat surfaces of SrVO3, which gave us the great opportunity to visualize correlated electronic state at atomic scale by means of spectroscopic imaging scanning tunneling spectroscopy. Based on the experimental data, we discuss spectroscopic signature of many body effects on the surface of SrVO3 system.

  3. Equivalent circuit for VO2 phase change material film in reconfigurable frequency selective surfaces

    International Nuclear Information System (INIS)

    We developed equivalent circuits of phase change materials based on vanadium dioxide (VO2) thin films. These circuits are used to model VO2 thin films for reconfigurable frequency selective surfaces (FSSs). This is important as it provides a way for designing complex structures. A reconfigurable FSS filter using VO2 ON/OFF switches is designed demonstrating −60 dB isolation between the states. This filter is used to provide the transmission and reflection responses of the FSS in the frequency range of 0.1–0.6 THz. The comparison between equivalent circuit and full-wave simulation shows excellent agreement

  4. TRANSPORTE DE VOZ (VoIP) SOBRE REDES IPv4 e IPv6

    OpenAIRE

    Fausto Alexander Gamboa; Octavio José Salcedo Parra

    2012-01-01

    El presente artículo tiene como finalidad evaluar el comportamiento de la VoIP en redes IPv6 y compararlo con IPv4, de igual manera presentar las arquitecturas que la soportan. Con el fin de que los resultados sean los más cercanos a la realidad, el artículo no solo se soporta en simulaciones si no en implementaciones reales. Dentro de las conclusiones más sobresalientes se encontró que la VoIP6 presenta mejor rendimiento ante el Jitter y el retardo que VoIPv4.

  5. VoIP Performance with Aggressive AMC and SINR Feedback for WiMAX Downlink

    Science.gov (United States)

    Fan, Xiangning; Dengkui, Zhu

    WiMAX system is based on OFDMA, and it is very suitable for VoIP traffic. At the same time, aggressive AMC and frame bundling are two important techniques to improve the performance of VoIP, and so they are applied to WiMAX system in this paper. The simulation results show that when the system is in short of bandwidth, these two techniques indeed reduce the PER and delay jitter of the VoIP users, and also enhance the spectrum efficiency.

  6. Energy star compliant voice over internet protocol (VoIP) telecommunications network including energy star compliant VoIP devices

    Science.gov (United States)

    Kouchri, Farrokh Mohammadzadeh

    2012-11-06

    A Voice over Internet Protocol (VoIP) communications system, a method of managing a communications network in such a system and a program product therefore. The system/network includes an ENERGY STAR (E-star) aware softswitch and E-star compliant communications devices at system endpoints. The E-star aware softswitch allows E-star compliant communications devices to enter and remain in power saving mode. The E-star aware softswitch spools messages and forwards only selected messages (e.g., calls) to the devices in power saving mode. When the E-star compliant communications devices exit power saving mode, the E-star aware softswitch forwards spooled messages.

  7. Determinants of peak VO2 in heart transplant recipients / Determinantes do pico de VO2 em transplantados cardacos

    Scientific Electronic Library Online (English)

    Vitor Oliveira, Carvalho; Guilherme Veiga, Guimares; Marcelo Luiz, Campos-Vieira; Aparecida Maria, Catai; Vagner, Oliveira-Carvalho; Silvia Moreira, Ayub-Ferreira; Edimar Alcides, Bocchi.

    2015-02-01

    Full Text Available Objetivo: Estabelecer os determinantes do VO2 pico em transplantados de corao. Mtodos: Avaliao do paciente foi realizada em dois dias consecutivos. No primeiro dia, os pacientes realizaram a avaliao da variabilidade da frequncia cardaca seguida de um teste de esforo cardiopulmonar. No seg [...] undo dia, os pacientes realizaram ecocardiografia de repouso. Os transplantados foram elegveis se estivessem em uma condio estvel e sem qualquer evidncia de rejeio diagnosticada por bipsia endomiocrdica. Pacientes com marca-passo, limitaes funcionais no cardiovasculares, tais como osteoartrite e doena pulmonar obstrutiva crnica foram excludos deste estudo. Resultados: Sessenta pacientes (68% do sexo masculino, 48 anos e 64 meses aps o transplante cardaco) foram avaliados. A anlise multivariada selecionou as seguintes variveis: sexo (P=0,001), idade (P=0,049), ndice de Massa Corporal (P=0,005), frequncia cardaca de reserva (P Abstract in english Objective: To establish the determinants of the peak VO2 in heart transplant recipients. Methods: Patient's assessment was performed in two consecutive days. In the first day, patients performed the heart rate variability assessment followed by a cardiopulmonary exercise test. In the second day, pa [...] tients performed a resting echocardiography. Heart transplant recipients were eligible if they were in a stable condition and without any evidence of tissue rejection diagnosed by endomyocardial biopsy. Patients with pacemaker, noncardiovascular functional limitations such as osteoarthritis and chronic obstructive pulmonary disease were excluded from this study. Results: Sixty patients (68% male, 48 years and 64 months following heart transplantation) were assessed. Multivariate analysis selected the following variables: receptor's gender (P=0.001), receptor age (P=0.049), receptor Body Mass Index (P=0.005), heart rate reserve (P

  8. Analisis Unjuk Kerja Aplikasi VoIP Call Android di Jaringan MANET [Performance Analysis of VoIP Call Application Android in MANET (Mobile Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Ryan Ari Setyawan

    2015-07-01

    Full Text Available Penelitian ini bertujuan menganalisis kinerja aplikasi  VoIP call android di jaringan MANET (mobile ad hoc network.  Hasil pengujian menunjukan bahwa aplikasi VoIP call android dapat digunakan di jaringan MANET. Delay yang dihasilkan paling besar di pengujian indoor dengan jarak 11-15 meter yakni sebesar 0,014624811 seconds. Packet loss yang dihasilkan pada range 1%-2% sedangkan standar packet loss yang ditetapkan oleh CISCO untuk layanan aplikasi VoIP adalah < 5%. Jitter yang dihasilkan yakni antara 0,01-0,06 seconds sedangkan standar yang ditetapkan oleh CISCO adalah ≤ 30 ms atau 0,03 seconds. Throughput yang dihasilkan pada proses pengujian yakni antar 161 kbps-481 kbps. *****This study aims to analyze the performance of VOIP call android application in the MANET (mobile ad hoc network. The results showed that VoIP applications could be implemented in MANET network. The highest  delay is produced in indoor testing  with distance of 11-15 meters,  which is equal to 0.014624811 seconds. Packet loss is generated in the range of 1% -2%, while packet loss standards set by Cisco for VoIP application services are <5%. The jitter is between 0.01 to 0.06 seconds, while the standard set by CISCO is ≤ 30 ms or 0.03 seconds. Throughput generated in the testing process is between 161 kbps-481 kbps.

  9. Determinación de las reservas de carbono de la biomasa aérea, en diferentes sistemas de uso de la tierra en San Martín, Perú

    Directory of Open Access Journals (Sweden)

    Tatiana Lapeyre

    2004-01-01

    Full Text Available Se determinó la biomasa aérea en diferentes sistemas de uso de la tierra en la región de San Martín-Perú, con la finalidad de conocer el potencial de captura de carbono. Los sistemas de uso de la tierra evaluados fueron: Bosque primario, Bosque secundario de diferentes edades, sistemas agrícolas locales maíz (Zea maiz, arroz (Oriza Sativa, pastos (Brachiaria y sistemas agroforestales con café (Coffea arabica bajo sombra y cacao (Cacao sp.. También se comparó este potencial con otros sistemas de uso de la tierra de otras regiones del Perú y se monitoreó la pérdida de reservas de carbono después del corte de la foresta y su reemplazo por cultivos. En cada uno de éstos sistemas se establecieron al azar cinco transectos donde se evaluó la biomasa arbórea. Dentro de éstos transectos se establecieron cuadrados también al azar para cuantificar la biomasa herbácea y la biomasa de hojarasca. El carbono total en el bosque primario fue de 485 tm C ha-1, superando ampliamente las reservas del bosque secundario de 50 años y de bosque descremado de 20 años. Con relación al bosque primario se observa una reducción de reservas en más de 50% del bosque secundario de 50 años (234 tm C ha-1. El bosque descremado de 20 años perdió más del 80% de reservas (62 tm C ha-1. El nivel de reservas de carbono en la biomasa de hojarasca de los sistemas boscosos, no es significativo al compararlo con el total de las reservas de carbono de la biomasa aérea; sin embargo si es significativo para sistemas agroforestales. Los sistemas agroforestales secuestraron entre 19 a 47 tm C ha-1, dependiendo de la cantidad de especies forestales, tipo de cultivo, edad y tipo de suelo y recuperan el potencial de captura en forma productiva. Los sistemas agrícolas capturaron poco C (5 tm C ha-1, además generan fugas de gases efecto invernadero (GEI cuando se usan agroquímicos y quema de rastrojos, entre otros.

  10. Electrochemical behavior of [(Mn(Bpy))(VO3)2]?(H2O)1.24 and [(Mn(Bpy)0.5)(VO3)2]?(H2O)0.62 inorganicorganic Brannerites in lithium and sodium cells

    International Nuclear Information System (INIS)

    The performance of MnV2O6 (MnV) and its [(Mn(Bpy))(VO3)2]?(H2O)1.16 (MnBpy) and [(Mn(Bpy)0.5)(VO3)2]?(H2O)0.62(MnBpy0.5) hybrid derivative compounds was investigated against sodium and lithium counter electrodes. For MnV2O6 stable capacities of 850 mAh/g were achieved in lithium cells, the best value reported so far. The whole capacity is ascribed to a conversion reaction in which the amorphization of the compounds takes place. No significant differences in the capacities for the inorganic compound and the hybrid ones were observed. Interestingly, the potential hysteresis decreases in the hybrid compounds. The difference between Li and Na cell capacity most probably comes from the difference of standard potential of the two redox couples Li+/Li and Na+/Na of about ca. 0.3 V leading to an incomplete conversion reaction and thus lowers capacity in the case of Na cells. The Raman and IR ex-situ experiments after cycling indicate that the bipyridine organic ligands are completely decomposed during the electrochemical testing. The IR studies in MnV inorganic and MnBpy and MnBpy0.5 hybrid electrodes after the electrochemical cycling, suggest that the SEI formation and bipyridine degradation give rise to different aliphatic compounds. - Graphical abstract: The electrochemical performance of [(Mn(Bpy))(VO3)2]?(H2O)1.16 and [(Mn(Bpy)0.5)(VO3)2]?(H2O)0.62 against sodium and lithium counter electrodes give rise to the structural collapse of the initial compounds. The IR and Raman studies show that the Bpy organic ligand is completely decomposed during the during the electrochemical testing. However, after the amorphization stable capacities as high as 850 mAh/g for lithium cells were achieved. - Highlights: We test the lithium and sodium insertion in hybrid brannerites. Capacities as large as 850 mAh/g were obtained for the Li cells. The capacity and good cycling is ascribed to a conversion reaction of the electrodes. The Bpy molecule of the hybrid compounds is degraded during the first reduction. The decomposition products of the Bpy ligand reduce the potential hysteresis

  11. Chapter 18: Web-based Tools - NED VO Services

    Science.gov (United States)

    Mazzarella, J. M.; NED Team

    The NASA/IPAC Extragalactic Database (NED) is a thematic, web-based research facility in widespread use by scientists, educators, space missions, and observatory operations for observation planning, data analysis, discovery, and publication of research about objects beyond our Milky Way galaxy. NED is a portal into a systematic fusion of data from hundreds of sky surveys and tens of thousands of research publications. The contents and services span the entire electromagnetic spectrum from gamma rays through radio frequencies, and are continuously updated to reflect the current literature and releases of large-scale sky survey catalogs. NED has been on the Internet since 1990, growing in content, automation and services with the evolution of information technology. NED is the world's largest database of crossidentified extragalactic objects. As of December 2006, the system contains approximately 10 million objects and 15 million multi-wavelength cross-IDs. Over 4 thousand catalogs and published lists covering the entire electromagnetic spectrum have had their objects cross-identified or associated, with fundamental data parameters federated for convenient queries and retrieval. This chapter describes the interoperability of NED services with other components of the Virtual Observatory (VO). Section 1 is a brief overview of the primary NED web services. Section 2 provides a tutorial for using NED services currently available through the NVO Registry. The "name resolver" provides VO portals and related internet services with celestial coordinates for objects specified by catalog identifier (name); any alias can be queried because this service is based on the source cross-IDs established by NED. All major services have been updated to provide output in VOTable (XML) format that can be accessed directly from the NED web interface or using the NVO registry. These include access to images via SIAP, Cone- Search queries, and services providing fundamental, multi-wavelength extragalactic data such as positions, redshifts, photometry and spectral energy distributions (SEDs), and sizes (all with references and uncertainties when available). Section 3 summarizes the advantages of accessing the NED "name resolver" and other NED services via the web to replace the legacy "server mode" custom data structure previously available through a function library provided only in the C programming language. Section 4 illustrates visualization via VOPlot of an SED and the spatial distribution of sources from a NED All-Sky (By Parameters) query. Section 5 describes the new NED Spectral Archive, illustrating how VOTables are being used to standardize the data and metadata as well as the physical units of spectra made available by authors of journal articles and producers of major survey archives; quick-look spectral analysis through convenient interoperability with the SpecView (STScI) Java applet is also shown. Section 6 closes with a summary of the capabilities described herein, which greatly simplify interoperability of NED with other components of the VO, enabling new opportunities for discovery, visualization, and analysis of multiwavelength data.

  12. Diamagnetic to ferromagnetic switching in VO2 epitaxial thin films by nanosecond excimer laser treatment

    Science.gov (United States)

    Molaei, R.; Bayati, R.; Nori, S.; Kumar, D.; Prater, J. T.; Narayan, J.

    2013-12-01

    VO2(010)/NiO(111) epitaxial heterostructures were integrated with Si(100) substrates using a cubic yttria-stabilized zirconia (c-YSZ) buffer. The epitaxial alignment across the interfaces was determined to be VO2(010)?NiO(111)?c-YSZ(001)?Si(001) and VO2[100]?NiO?110??c-YSZ?100??Si?100?. The samples were subsequently treated by a single shot of a nanosecond KrF excimer laser. Pristine as-deposited film showed diamagnetic behavior, while laser annealed sample exhibited ferromagnetic behavior. The population of majority charge carriers (e-) and electrical conductivity increased by about two orders of magnitude following laser annealing. These observations are attributed to the introduction of oxygen vacancies into the VO2 thin films and the formation of V3+ defects.

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

    DEFF Research Database (Denmark)

    Dencker, Magnus; Hermansen, Bianca; Bugge, Anna; Froberg, Karsten; Andersen, Lars B

    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%....

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

    Science.gov (United States)

    Watzlaf, Valerie R; Ondich, Briana

    2012-01-01

    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 clients/consumers. PMID:25945194

  15. VoIP over Multiple IEEE 802.11 Wireless LANs

    OpenAIRE

    Chan, A.; Liew, S. C.

    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...

  16. Body fat, abdominal fat and body fat distribution related to VO(2PEAK) in young children

    DEFF Research Database (Denmark)

    Dencker, Magnus; Wollmer, Per; Karlsson, Magnus K; Lindén, Christian; Andersen, Lars Bo; Thorsson, Ola

    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...

  17. Synthesis and characterization of VO2+ doped ZnO-CdS composite nanopowder

    Science.gov (United States)

    Thirumala Rao, G.; Babu, B.; Joyce Stella, R.; Pushpa Manjari, V.; Venkata Reddy, Ch.; Shim, Jaesool; Ravikumar, R. V. S. S. N.

    2015-02-01

    VO2+ doped ZnO-CdS composite nanopowder has been synthesized by chemical precipitation method. The prepared sample has been characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR, photoluminescence (PL), optical absorption and EPR spectroscopy. From XRD pattern, average crystallite size is about 18 nm. SEM and TEM images showed sphere like structures. FT-IR spectrum indicates the presence of fundamental modes of ZnO, CdS and other functional groups. The PL spectrum of VO2+ doped ZnO-CdS composite nanopowder exhibits UV, blue and green emissions. Optical and EPR studies revealed the tetragonal compressed octahedral site symmetry for VO2+ ions. The bonding between VO2+ and its ligands is ionic.

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

    Science.gov (United States)

    Dencker, Magnus; Hermansen, Bianca; Bugge, Anna; Froberg, Karsten; Andersen, Lars B

    2011-02-01

    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%. PMID:21467593

  19. Influence of thermal boundary conditions on the current-driven resistive transition in VO2 microbridges

    Science.gov (United States)

    Manca, Nicola; Kanki, Teruo; Tanaka, Hidekazu; Marr, Daniele; Pellegrino, Luca

    2015-10-01

    We investigate the resistive switching behaviour of VO2 microbridges under current bias as a function of temperature and thermal coupling with the heat bath. Upon increasing the electrical current bias, the formation of the metallic phase can progress smoothly or through sharp jumps. The magnitude and threshold current values of these sharp resistance drops show random behaviour and are dramatically influenced by thermal dissipation conditions. Our results also evidence how the propagation of the metallic phase induced by electrical current in VO2, and thus the shape of the resulting high-conductivity path, are not predictable. We discuss the origin of the switching events through a simple electro-thermal model based on the domain structure of VO2 films that can be useful to improve the stability and controllability of future VO2-based devices.

  20. Roles of grain boundaries on the semiconductor to metal phase transition of VO2 thin films

    International Nuclear Information System (INIS)

    Vanadium dioxide (VO2) thin films with controlled grain sizes are deposited on amorphous glass substrates by pulsed laser deposition. The grain boundaries (GBs) are found as the dominating defects in the thin films. The semiconductor to metal transition (SMT) properties of VO2 thin films are characterized and correlated to the GB density. The VO2 films with lower GB density exhibit a sharper SMT with a larger transition amplitude. A high resolution TEM study at GB area reveals the disordered atomic structures along the boundaries and the distorted crystal lattices near the boundaries. The VO2 SMT amplitude and sharpness could be directly related to these defects at and near the boundaries

  1. High performance of solvothermally prepared VO2(B as anode for aqueous rechargeable lithium batteries

    Directory of Open Access Journals (Sweden)

    Milošević Sanja

    2015-01-01

    Full Text Available The VO2 (B was synthesized via a simple solvothermal route at 160oC in ethanol. The initial discharge capacity of VO2 (B anode, in saturated aqueous solution of LiNO3, was 177 mAh g-1 at a current rate of 50 mA g-1. After 50 cycles capacity fade was 4%, but from 20th-50th cycle no capacity drop was observed. The VO2 (B has shown very good cyclability at current rate of even 1000 mA g-1 with initial discharge capacity of 92 mAh g-1. The excellent electrochemical performance of VO2 (B was attributed to the stability of micro-nano structures to repeated intercalation /deintercalation process, very good electronic conductivity as well as the very low charge transfer resistance in the aqueous electrolyte. [Projekat Ministarstva nauke Republike Srbije, br. III45014

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

    Directory of Open Access Journals (Sweden)

    Valerie R. Watzlaf

    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. 

  3. Effects of erythrocyte infusion on VO2max at high altitude

    DEFF Research Database (Denmark)

    Young, Jette Feveile; Sawka, M N; Muza, S R; Boushel, Robert Christopher; Lyons, T; Rock, P B; Freund, B J; Waters, Ryan; Cymerman, A; Pandolf, K B; Valeri, C R

    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...... increasing arterial O2-carrying capacity, autologous erythrocyte infusion did not ameliorate the decrement in VO2max at 4,300-m altitude....

  4. Sr$_2$(Ba$_2$)VO$_4$ under pressure -- an orbital switch and potential $d^1$ superconductor

    CERN Document Server

    Arita, R; Held, K; Matsuno, J; Kuroki, K

    2006-01-01

    We study Sr$_2$(Ba$_2$)VO$_4$ under high pressure by means of the local density approximation + dynamical mean field theory method. While Sr$_2$VO$_4$ is a 1/6-filling three-band system at ambient pressure with a small level splitting between the $d_{xy}$- and $d_{yz/zx}$-bands, we show that an orbital polarization occurs under uniaxial pressure, resulting in dramatic changes of the magnetic, optical, and transport properties. When pressure is applied in the $c$-direction, a $d^1$ analog of $d^9$ cuprates is realized, making Sr$_2$(Ba$_2$)VO$_4$ a possible candidate for a $d^1$ superconductor. Experimentally, this uniaxial pressure can be realized by growing Ba$_2$VO$_4$ on a substrate with lattice constant 4.1-4.2 \\AA.

  5. TiVo heitlus elu prast / John Gartner ; tlk. Peeter Peetersoo

    Index Scriptorium Estoniae

    Gartner, John

    2005-01-01

    Peale interaktiivse salvestusseadme TiVo turuletulekut 1997. aastal ei ole ettevte vaatamate toote headusele suutnud saavutada ootuspraseid mgitulemusi ega saada suurt kasumit. Artiklis tutvustatakse ettevtte heitlusi partnerite otsinguil ja edu saavutamisel

  6. Mobile telephones: a comparison of radiated power between 3G VoIP calls and 3G VoCS calls.

    Science.gov (United States)

    Jovanovic, Dragan; Bragard, Guillaume; Picard, Dominique; Chauvin, Sébastien

    2015-01-01

    The purpose of this study is to assess the mean RF power radiated by mobile telephones during voice calls in 3G VoIP (Voice over Internet Protocol) using an application well known to mobile Internet users, and to compare it with the mean power radiated during voice calls in 3G VoCS (Voice over Circuit Switch) on a traditional network. Knowing that the specific absorption rate (SAR) is proportional to the mean radiated power, the user's exposure could be clearly identified at the same time. Three 3G (High Speed Packet Access) smartphones from three different manufacturers, all dual-band for GSM (900 MHz, 1800 MHz) and dual-band for UMTS (900 MHz, 1950 MHz), were used between 28 July and 04 August 2011 in Paris (France) to make 220 two-minute calls on a mobile telephone network with national coverage. The places where the calls were made were selected in such a way as to describe the whole range of usage situations of the mobile telephone. The measuring equipment, called "SYRPOM", recorded the radiation power levels and the frequency bands used during the calls with a sampling rate of 20,000 per second. In the framework of this study, the mean normalised power radiated by a telephone in 3G VoIP calls was evaluated at 0.75% maximum power of the smartphone, compared with 0.22% in 3G VoCS calls. The very low average power levels associated with use of 3G devices with VoIP or VoCS support the view that RF exposure resulting from their use is far from exceeding the basic restrictions of current exposure limits in terms of SAR. PMID:25352159

  7. Effect of annealing temperature on the structure and electrochemistry of LiVO3

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Abstract: Single-phase LiVO3 with a monoclinic structure (S.G. C2/c) was prepared by mechanochemically assisted solid state synthesis using V2O5 and Li2CO3 as raw materials. The reagent mixtures, activated by means of a high-energy planetary mill AGO-2, were annealed at 350, 450 and 550 °C in air. Thus-prepared LiVO3 samples were characterized by XRD using the Rietveld refinement, SEM, TEM, HRTEM, FTIR, Raman spectroscopy, 6Li and 51V MAS NMR spectroscopy, XPS, galvanostatic cycling, and GITT. The average particle size increases from ∼100 nm for LiVO3-350 °C to some micrometers for LiVO3-550 °C along with the degree of crystallinity. XRD, FTIR, 6Li and 51V MAS NMR reveal the largest degree of structural distortion for the LiVO3-350 °C sample. Ex situ XRD confirms a biphasic mechanism of the initial lithium intercalation in LiVO3 and a single-phase mechanism for a fully lithiated Li2VO3. The rock salt type structure of Li2VO3 (S.G. Fd-3m) keeps unchanged during the following cycling; a lattice parameter a increases upon delithiation from 8.22 Å to 8.29 Å (2.5%). According to XPS, lithiation of LiVO3 is accompanied by V5+/V4+ redox couple. The nanosized LiVO3-350 °C sample exhibits the largest initial discharge capacity (317 mA h g−1), however followed by a progressive decay due to the presence of structural distortion. On the contrary, LiVO3-450 °C sample is characterized by better capacity retention and high-rate performance. The average value of Li-ion diffusion coefficient determined from the GITT measurements is the 10−12 cm2 s−1; it does not noticeably change vs. Li content

  8. QoS Analysis for Signaling in VoIP Client and Server Communication for Multicore

    OpenAIRE

    Adnan, Muhammad

    2012-01-01

    Due to the cost-effective solutions provided by Voice over Internet Protocol (VoIP) technology to enterprises and individuals, the growth has been significantly high in this area during the past and current decade. The growing demand has resulted in the escalating number of users who need secure, reliable and efficient communication systems. The deployment of multicore hardware has been solving the computational complexity problems. A multicore hardware/software model for VoIP is the key rese...

  9. Gauging VoIP Call Quality from 802.11 WLAN Resource Usage

    OpenAIRE

    Narbutt, Miroslaw; Davis, Mark

    2006-01-01

    In this paper we experimentally study the relationship between resource utilization in the wireless LAN and the quality of VoIP calls transmitted over the wireless medium. Specifically we evaluate how its overall capacity is shared between three basic MAC bandwidth components (load, access and free) as the number of VoIP calls increases and how it influences transmission impairments (delay, loss and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framew...

  10. Evaluation and Investigation of the Delay in VoIP Networks

    Directory of Open Access Journals (Sweden)

    V. Janata

    2011-06-01

    Full Text Available The paper is focused mainly on the delay problems, which considerably influence the final quality of connections in VoIP (Voice over IP networks. The paper provides a detailed exploration of the nature and mechanisms of the delay. The main purpose of the investigation was an attempt to formulate a mathematical model of delay in the VoIP network and its subsequent analysis by laboratory data.

  11. Malicious traffic monitoring and its evaluation in VoIP infrastructure

    OpenAIRE

    Safarik, Jakub; Voznak, Miroslav; Rezac, Filip; Macura, Lukas

    2012-01-01

    The paper deals with the need to enhance security of the VoIP infrastructure. There are several ways to achieve an enhancement in security. We opted for the honeypot which can provide us information about attacker’s behaviour. We will examine in particular a VoIP honeypot referred to as Artemisa. It is one of many existing honeypots tailored for IP telephony. The paper describes its function and application within a real IP telephony infrastructure. The aim of another tes...

  12. Evaluation and Investigation of the Delay in VoIP Networks

    OpenAIRE

    Janata, V.; M. Kovacik; Baronak, I.; Kyrbashov, B.

    2011-01-01

    The paper is focused mainly on the delay problems, which considerably influence the final quality of connections in VoIP (Voice over IP) networks. The paper provides a detailed exploration of the nature and mechanisms of the delay. The main purpose of the investigation was an attempt to formulate a mathematical model of delay in the VoIP network and its subsequent analysis by laboratory data.

  13. Risk Management in VoIP Infrastructures using Support Vector Machines

    OpenAIRE

    Nassar, Mohamed; Dabbebi, Oussema; Badonnel, Rémi; Festor, Olivier

    2010-01-01

    Telephony over IP is exposed to multiple security threats. Conventional protection mechanisms do not fit into the highly dynamic, open and large-scale settings of VoIP infrastructures, and may significantly impact on the performance of such a critical service. We propose in this paper a runtime risk management strategy based on anomaly detection techniques for continuously adapting the VoIP service exposure. This solution relies on support vector machines (SVM) and exploits dynamic security sa...

  14. Managing Risks at Runtime in VoIP Networks and Services

    OpenAIRE

    Dabbebi, Oussema; Badonnel, Remi; Festor, Olivier

    2010-01-01

    IP telephony is less confined than traditional PSTN telephony. As a consequence, it is more exposed to security attacks. These attacks are specific to VoIP protocols such as SPIT, or are inherited from the IP layer such as ARP poisoning. Protection mechanisms are often available, but they may seriously impact on the quality of service of such critical environments. We propose to exploit and automate risk management methods and techniques for VoIP infrastructures. Our objective is to dynamical...

  15. VoIP Implementation and Experiments on a Mobile Wireless AdHoc Network

    Science.gov (United States)

    Zhang, Hongqi; Yang, Oliver; Zhao, Jiying

    We have implemented a testbed to study the performance of VoIP in wireless ad hoc networks. The ASNC (Adaptive Source Network-rate Control) scheme is used to battle packet loss by feeding MOS (Mean Opinion Score) and loss information back to the sender. Our different VoIP experiments with measurements on delay, packet loss rate and MOS have validated the feasibility and efficiency of our scheme. It further verifies the simulator we used in the initial investigation.

  16. Prepaid and Postpaid VoIP Service Enhancements and Hybrid Network Performance Measurement

    OpenAIRE

    Mohd Nazri Ismail; Asaad Abusin

    2006-01-01

    This study focuses on prepaid and postpaid VoIP technology service enhancement. The aims are to i) merge wireless technology in rural areas with wired technologies and services in urban areas. It intends to investigate the minimum requirement needs by wireless and wired technology in using of telco connectivity. It is also to define which technology will achieve a low operating cost and good performance. In addition, the most apparent benefit of implementing prepaid/postpaid VoIP network in r...

  17. Performance Analysis of Statistical Distributions for VoIP over WiMAX Access Networks

    OpenAIRE

    Gysberth Maurits Wattimena

    2013-01-01

    Statistical distributions are used to represent behavior of real VoIP traffic. This paper investigates the performance of VoIP traffic over WiMAX networks by examining statistical comparison of interarrival time distribution. The parameters are used to analyze the Quality of Service (QoS), like delay, jitter, throughput with respect to Voice Activity Detection (VAD) or Silence Detection (SD) in voice codec G.729. The simulation result indicates that the pareto distribution in interarrival tim...

  18. 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 ...

  19. Synthesis and characterization of Ag/BiVO4 composite photocatalyst

    International Nuclear Information System (INIS)

    Ag/BiVO4 composite photocatalysts were hydrothermal synthesized and characterized by XRD, SEM, XPS and DRS techniques. Their photocatalytic activities were determined by oxidative decomposition of methyl orange in aqueous solution under visible light irradiation. It revealed that the doped Ag species greatly improved the visible light absorption abilities and morphologies of the composites, and thus lead to enhanced photocatalytic activities compared with that of the pure BiVO4.

  20. 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

  1. Evolution of Spin-Orbital-Lattice Coupling in the $R$VO$_3$ Perovskites

    OpenAIRE

    Horsch, Peter; Oles, Andrzej M.; Feiner, Louis Felix; Khaliullin, Giniyat

    2008-01-01

    We introduce a microscopic model which unravels the physical mechanisms responsible for the observed phase diagram of the $R$VO$_3$ perovskites. It reveals a nontrivial interplay between superexchange, the orbital-lattice coupling due to the GdFeO$_3$-like rotations of the VO$_6$ octahedra, and orthorhombic lattice distortions. We find that the lattice strain affects the onset of the magnetic and orbital order by partial suppression of orbital fluctuations. The present approach provides also ...

  2. Slowed Exercise-Onset Vo(2) Kinetics During Submaximal Endurance Exercise in Subjects With Multiple Sclerosis

    OpenAIRE

    Hansen, Dominique; Wens, Inez; Kosten, Lauren; Verboven, Kenneth; Bert O Eijnde

    2013-01-01

    Background. Low physical activity levels in persons with multiple sclerosis (MS) may reduce skeletal muscle oxidative capacity. Rehabilitation strategies might be altered by a measure of capacity that did not require invasive techniques or maximal exercise testing. For this purpose, we measured exercise onset and offset oxygen uptake (Vo(2)) kinetics during endurance exercise. Objective. This study compared exercise-onset and -offset Vo(2) kinetics in mildly affected persons with MS with heal...

  3. 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...

  4. VO Access to the HST Snapshot Survey of 3C Radio Galaxies

    Science.gov (United States)

    Allen, Mark

    2007-08-01

    HST snapshot surveys of the 3C sample of radio galaxy hosts have collected a wealth of UV, optical and IR imaging data on these objects. We describe how science-ready data from these surveys is being made available in the VO via the ‘Système Automatique d'Archivage de Données Astronomiques' (SAADA) database generator, and how it is being exploited with VO tools.

  5. 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.

  6. 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.

  7. Li+ intercalation in isostructural Li2VO3 and Li2VO2 with O2- and mixed O2-/F- anions

    OpenAIRE

    Chen, R.; Ren, S; YAVUZ, M.; Guda, A. A.; Shapovalov, V.; Witter, R.; Fichtner, M.; Hahn, H.

    2015-01-01

    Mixed-anion materials for Li-ion batteries have been attracting attention in view of their tunable electrochemical properties. Herein, we compare two isostructural (Fm3m) model intercalation materials Li2VO3 and Li2VO2F with O2- and mixed O2-/F- anions, respectively. Synchrotron X-ray diffraction and pair distribution function data confirm large structural similarity over long-range and at the atomic scale for these materials. However, they show distinct electrochemical properties and kinetic...

  8. Selective synthesis of monoclinic and tetragonal phase LaVO4 nanorods via oxides-hydrothermal route

    International Nuclear Information System (INIS)

    Pure monoclinic (m-) and tetragonal (t-) LaVO4 nanorods are successfully obtained via a facile oxides-hydrothermal method, in which V2O5 and La2O3 bulk powders are directly utilized as precursors without pretreatment. It is found that ethylenediamine tetraacetic disodium salt (EDTA) is a key factor for synthesizing t-LaVO4. The as-obtained products are characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED). The FTIR spectra of VO4 around 800 cm-1 are suggested as an effective auxiliary means to identify the crystal phase of LaVO4. UV-Visible spectra of LaVO4 nanomaterials are obvious blue shift compared with the bulk m-LaVO4 materials. The different photoluminescent properties of Eu3+ doped m- and t-LaVO4 are demonstrated. A dissolution-precipitation mechanism is mainly responsible for the anisotropic morphology and phase control evolution of the LaVO4 nanocrystals. The oxides-hydrothermal system is also applicable to prepare other pure LnVO4 (Ln3+: Nd3+, Y3+, Sm3+) and doped LnVO4 nanomaterials

  9. Conversión de biomasa recalcitrante originada en la producción de etanol a partir de la planta de banano y su fruto en combustibles mediante procesos de pirolisis

    OpenAIRE

    Giraldo Rivera, Oscar Darío

    2012-01-01

    Se estudió la pirólisis de la biomasa recalcitrante (residuos sólidos de la planta de banano y su fruto obtenidos del proceso de extracción del etanol) en un reactor de caída libre a escala de laboratorio. El sistema de experimentación, diseñado específicamente para este estudio, permite caracterizar la pirólisis de la biomasa en un régimen que se encuentra entre la pirólisis rápida y la lenta dada la alta velocidad de calentamiento y el corto tiempo de residencia de la partícula, pero a su v...

  10. Conductividad térmica del suelo, materia orgánica, actividad y biomasa microbianas en sistemas de cultivo de maracuyá en toro, valle del cauca

    OpenAIRE

    Rojas, Adriana; Zúñiga, Orlando; Sánchez de Prager, Marina; Pérez, Jesús; Gascó, José María

    2007-01-01

    El estudio evaluó la relación entre la conductividad térmica del suelo (λ), la materia orgánica, la actividad y la biomasa microbianas. En tres sistemas de cultivo de maracuyá (agroecológico, transición y convencional) en el municipio de Toro (Valle del Cauca), en nueve puntos por manejo se tomaron muestras al azar a dos profundidades (0-15 y 15-30 cm) y se midieron propiedades biológicas: (actividad microbiana (C-CO2); biomasa microbiana (C microbiano) –fumigación, extracción– y propied...

  11. Del manejo multifuncional del territorio a la desarticulación productiva: cambios en los flujos de biomasa durante el proceso de industrialización de la agricultura gallega (1960-2012)

    OpenAIRE

    Soto Fernández, David

    2015-01-01

    En este trabajo se ofrece una serie anual de los flujos de Biomasa vegetal en Galicia durante el periodo 1960-2012. El marco cronológico elegido abarca el periodo final del sistema agrario orgánico, las consecuencias el proceso de industrialización de la agricultura gallega y el impacto de la integración de España en la Unión Europea. En el trabajo se proporcionan varios indicadores habituales en el análisis biofísico de la agricultura, como la Extracción Doméstica de biomasa y la división de...

  12. Calorimetria indireta na monitorao hemodinmica e metablica em ces sob diferentes situaes hemodinmicas

    Directory of Open Access Journals (Sweden)

    M. I. Gehrcke

    2015-10-01

    Full Text Available RESUMOA monitorao do estado hemodinmico visa ao equilbrio entre a oferta e a demanda de oxignio tecidual. O objetivo deste estudo foi avaliar a utilizao da calorimetria indireta (CI frente termodiluio (TD em ces sob diferentes estados hemodinmicos. Utilizaram-se nove ces pesando 19,61,3kg, os quais foram anestesiados com isofluorano a 1,4V% (Basal, submetidos ventilao mecnica (VM e estados hipodinmico (Hipo, com isofluorano a 3,5V%, e hiperdinmico (Hiper, com dobutamina a 5g/kg/min. Utilizou-se um cateter de Swan-Ganz para aferio do ndice cardaco (IC por TD, clculo do consumo de oxignio pelo mtodo de Fick (VO2Fick e para coleta de sangue venoso central e misto. Com a CI, obtiveram-se os valores de consumo de oxignio (VO2, produo de CO2(VCO2 e expirado de CO2 (EtCO2. Para a determinao do IC por CI, utilizou-se o princpio de Fick com os valores de VO2 e os sangues arteriais e venosos misto (Fickmix ou central (Fickvc, e pela relao dos valores de VCO2 e EtCO2(FickCO2. A anlise estatstica compreendeu os testes de Dunnet, para diferena entre as fases, e Tukey, para diferenas entre os mtodos (P?0,05. Foram realizadas as anlises de correlao de Pearson e de concordncia de Bland-Altman. A CI forneceu valores de VO230 a 40% maiores que VO2Fick, mas identificou a reduo no VO2 aps a VM e Hipo, o que no ocorreu com VO2Fick. Os valores de VCO2diminuram nas fases VM e Hipo. Houve reduo do IC na fase Hipo com todos os mtodos e aumento na fase Hiper com TD e Fickvc. Os valores de IC pelos mtodos de Fickmixe Fickvc foram maiores que TD em todos os momentos, e FickCO2foi menor que TD na fase Hiper. Nenhum dos mtodos apresentou concordncia e correlao com a TD. Conclui-se que a CI pode ser utilizada na mensurao do VO2 e VCO2 de ces sob diferentes estados hemodinmicos. Contudo, embora seja possvel a identificao dos diferentes estados hemodinmicos, os valores de IC no podem ser comparados termodiluio.

  13. Preparation, characterization and photocatalytic properties of Cu-loaded BiVO4

    International Nuclear Information System (INIS)

    A series of Cu-loaded BiVO4 (Cu-BiVO4) catalysts were prepared by impregnation method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and special surface area. The photocatalytic activities of Cu-BiVO4 catalysts for the degradation of methylene blue (MB) were found to depend largely on the Cu content and the calcination temperature. The optimum Cu loading and calcination temperature were found to be 5 at.% and 300 deg. C, respectively. The results of XPS and SEM analysis indicated that Cu, CuO in this case, was dispersed on the surface of BiVO4. The results of DRS analysis showed that the Cu-BiVO4 series catalysts had significant optical absorption in the visible region between 550 and 800 nm and found that the absorption intensity increased with the enhancement of Cu content. An efficient N-demethylation of MB using Cu-BiVO4 catalyst (5 at.% Cu content) calcined at 300 deg. C was also observed

  14. 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.

  15. Tailoring Multilayered BiVO4 Photoanodes by Pulsed Laser Deposition for Water Splitting.

    Science.gov (United States)

    Murcia-López, Sebastián; Fàbrega, Cristian; Monllor-Satoca, Damián; Hernández-Alonso, María D; Penelas-Pérez, Germán; Morata, Alex; Morante, Juan R; Andreu, Teresa

    2016-02-17

    Pulsed laser deposition (PLD) is proposed as promising technique for the fabrication of multilayered BiVO4-based photoanodes. For this purpose, bare BiVO4 films and two heterojunctions, BiVO4/SnO2 and BiVO4/WO3/SnO2, have been prepared using consecutive ablation of assorted targets in a single batch. The ease, high versatility and usefulness of this technique in engineering the internal configuration of the photoanode with stoichiometric target-to-substrate transfer are demonstrated. The obtained photocurrent densities are among the highest reported values for undoped BiVO4 without oxygen evolution catalysts (OEC). A detailed analysis of the influence of SnO2 and WO3 layers on the charge transport properties because of the changes at the internal FTO/semiconductor interface is performed through transient photocurrent measurements (TPC), showing that the BiVO4/WO3/SnO2 heterostructure attains a significant decrease in the internal losses and reaches high photocurrent values. This study is expected to open the door to the fabrication of other systems based on ternary (or even more complex) metal oxides as photoanodes for water splitting, which is a promising alternative for obtaining materials able to fulfill the different requierements in the development of more efficient systems for this process. PMID:26804929

  16. Nanosheet-based BiVO4 hierarchical microspheres and their photocatalytic activity under visible light

    International Nuclear Information System (INIS)

    Hierarchical BiVO4 microspheres assembled by nanosheets were synthesized by hydrothermal process under microwave irradiation. The morphology and compositional characteristics of the BiVO4 architectures were investigated by SEM, TEM, and XRD. The possible formation mechanism for the architectures was discussed. UV-vis diffuse reflectance spectra indicated the BiVO4 hierarchical microspheres had absorption in both UV and vis light areas. The specific surface area and porosity of the BiVO4 architectures were investigated by using nitrogen adsorption and desorption isotherms. Because of the narrow bandgap and the novel micro-/nanostructure, the BiVO4 architectures show a more excellent photocatalytic activity under visible light irradiation than the BiVO4 solid microspheres and P25. Several possible reasons for the higher photocatalytic activity have been taken into consideration, namely, high specific surface area, hierarchical mesoporous structure, and quantum size effect. In addition, the photocatalyst is stable during the reaction and can be used repeatedly. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Tailoring of the thermomechanical performance of VO2 nanowire bimorph actuators by ion implantation

    Science.gov (United States)

    Karl, H.; Peyinghaus, S. C.

    2015-12-01

    Vanadium dioxide VO2 nanowire bimorph actuators work on the basis of the large abrupt length change at the metal-insulator phase transition (MIT). A key parameter for the bimorph performance and efficiency is the bending curvature and the width of the temperature hysteresis of the MIT which is inherently large for single domain VO2 metal side coated nanowires. In this work we present single-clamped Ir side coated VO2 bimorphs which show unprecedented high bending curvatures of up to 105 m-1 and new type of side ion-implanted VO2 nanowire bimorph actuators with a nearly completely suppressed temperature hysteresis. It is assumed that ion-beam induced radiation defects in the VO2 crystal structure act as nucleation sites for the MIT. Moreover it will be shown that mechanical strain intentionally built-in during VO2 nanowire bimorph fabrication allows to direct phase transformation via a strain stabilized metastable phase and thus allows to control bending response on temperature change.

  18. The preparation of a plasmonically resonant VO{sub 2} thermochromic pigment

    Energy Technology Data Exchange (ETDEWEB)

    Bai Huaping; Cortie, Michael B; Maaroof, Abbas I; Dowd, Annette; Kealley, Catherine; Smith, Geoffrey B [Institute for Nanoscale Technology, University of Technology Sydney, PO Box 123, Broadway, NSW 2007 (Australia)], E-mail: michael.cortie@uts.edu.au

    2009-02-25

    Vanadium dioxide (VO{sub 2}) undergoes a reversible metal-insulator transition, normally at {approx}68 {sup 0}C. While the properties of continuous semi-transparent coatings of VO{sub 2} are well known, there is far less information available concerning the potential use of discrete VO{sub 2} nanoparticles as a thermochromic pigment in opaque coatings. Individual VO{sub 2} nanoparticles undergo a localized plasmon resonance with near-infrared light at about 1100 nm and this resonance can be switched on and off by simply varying the temperature of the system. Therefore, incorporation of VO{sub 2} nanoparticles into a coating system imbues the coating with the ability to self-adaptively modulate its own absorptive efficiency in the near-infrared. Here we examine the magnitude and control of this phenomenon. Prototype coatings are described, made using VO{sub 2} powder produced by an improved process. The materials are characterized using calorimetry, x-ray diffraction, high-resolution scanning electron microscopy, transmission electron microscopy, and by measurement of optical properties.

  19. Modified Secret Sharing over a Single Path in VoIP with Reliable Data Delivery

    Directory of Open Access Journals (Sweden)

    K.Maheswari

    2012-01-01

    Full Text Available Abstract Voice over Internet Protocol (VoIP is a new fancy and up growing technology. A major change in telecommunication industry is VoIP. The transmission of Real time voice data is not as easy as ordinary text data. The real time voice transmission faces lot of difficulties. It suffers from packet loss, delay, quality and security. These factors will affects and degrade the performance and quality of a VoIP. This paper addresses the security and packet delivery ratio of a VoIP using modified secret sharing algorithm over a single path with reduced packet loss. The simulation results show that higher security and reduced packet loss is achieved in terms of end to end delay and packet delivery ratio. The user gets bad quality of VoIP at the receiver side. This makes the deployment of real time application a challenging task. To overcome these challenges in VoIP, several solutions have been reported already. The proper selection of active path in the routing protocol has a great impact in terms of packet delivery ratio and route discovery process. To provide end to end security between the source destination pair, the single path routing scheme is introduced.

  20. 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.

  1. Mechanochemical synthesis of nanostructured BiVO4 and investigations of related features

    International Nuclear Information System (INIS)

    Highly crystalline monoclinic bismuth vanadate (BiVO4) nanopowders with crystallite sizes less than 50 nm were obtained by mechanical milling of a stoichiometric mixture of bismuth oxide (Bi2O3) and vanadium pentoxide (V2O5). Different synthesized batches were obtained by varying the preparation times and the number of the tungsten carbide balls (BPR) while keeping constant the jar rotation speed. Annealing treatments were performed on the obtained nanopowders in order to improve the crystalline order and the BiVO4 nanoparticles surface states. Characterizations methods, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) equipped with X-ray energy dispersive spectrometer (EDS), Raman spectrometry, FTIR and UVVis diffuse reflectance techniques were used to shed light on the structure, morphologies and composition of the obtained nanopowders. Even if monoclinic BiVO4 crystalline structure was stabilized in samples after appropriate annealing, shifts of Raman peak positions after such treatments revealed the occurrence of symmetry distortions in the local structure of the monoclinic phase. -- Graphical abstract: Art Work BiVO4 Synthesis and Structures. Highlights: ? Synthesis by ball-milling of original nanostructures of BiVO4. ? Stabilizing a monoclinic BiVO4 polytype with nanoparticle sizes about 20 nm. ? Investigations of annealing effects on structures, vibration and optical features.

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

    Science.gov (United States)

    Santander-Vela, Juan de Dios; Garca, Emilio; Leon, Stephane; Espigares, Victor; Ruiz, Jos Enrique; Verdes-Montenegro, Lourdes; Solano, Enrique

    2012-11-01

    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 astronomical archives have been possible. We plan to adapt RADAMS to be able to deal with interferometry data in the future.

  3. Continuous tuning of W-doped VO{sub 2} optical properties for terahertz analog applications

    Energy Technology Data Exchange (ETDEWEB)

    Karaoglan-Bebek, G. [Department of Physics and Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Hoque, M. N. F.; Fan, Z.; Bernussi, A. A., E-mail: ayrton.bernussi@ttu.edu [Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Holtz, M. [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)

    2014-11-17

    Vanadium dioxide (VO{sub 2}), with its characteristic metal-insulator phase transition, is a prospective active candidate to realize tunable optical devices operating at terahertz (THz) frequencies. However, the abrupt phase transition restricts its practical use in analog-like continuous applications. Incorporation of tungsten is a feasible approach to alter the phase transition properties of thin VO{sub 2} films. We show that amplitude THz modulation depth of ?65%, characteristic phase transition temperature of ?40?C, and tuning range larger than 35?C can be achieved with W-doped VO{sub 2} films grown on sapphire substrates. W-doped VO{sub 2} films can also be used to suppress Fabry-Perot resonances at THz frequencies but at temperatures much lower than that observed for undoped VO{sub 2} films. The gradual phase transition temperature window allows for precise control of the W-doped VO{sub 2} optical properties for future analog based THz devices.

  4. Mechanochemical synthesis of nanostructured BiVO{sub 4} and investigations of related features

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesan, R. [Nanoscience and Nanotechnology program, CINVESTAV-IPN, Zacatenco, Av IPN 2508, Col Zacatenco, D.F., C.P. 07360 (Mexico); Institute of Molecules and Materials of Le Mans (IMMM) UMR CNRS, Universite du Maine, 72085 Le Mans (France); Velumani, S., E-mail: velu@cinvestav.mx [Nanoscience and Nanotechnology program, CINVESTAV-IPN, Zacatenco, Av IPN 2508, Col Zacatenco, D.F., C.P. 07360 (Mexico); Department of Electrical Engineering (SEES), CINVESTAV-IPN, Zacatenco, Av IPN 2508, Col Zacatenco, D.F., C.P. 07360 (Mexico); Kassiba, A., E-mail: kassiba@univ-lemans.fr [Institute of Molecules and Materials of Le Mans (IMMM) UMR CNRS, Universite du Maine, 72085 Le Mans (France)

    2012-08-15

    Highly crystalline monoclinic bismuth vanadate (BiVO{sub 4}) nanopowders with crystallite sizes less than 50 nm were obtained by mechanical milling of a stoichiometric mixture of bismuth oxide (Bi{sub 2}O{sub 3}) and vanadium pentoxide (V{sub 2}O{sub 5}). Different synthesized batches were obtained by varying the preparation times and the number of the tungsten carbide balls (BPR) while keeping constant the jar rotation speed. Annealing treatments were performed on the obtained nanopowders in order to improve the crystalline order and the BiVO{sub 4} nanoparticles surface states. Characterizations methods, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) equipped with X-ray energy dispersive spectrometer (EDS), Raman spectrometry, FTIR and UV-Vis diffuse reflectance techniques were used to shed light on the structure, morphologies and composition of the obtained nanopowders. Even if monoclinic BiVO{sub 4} crystalline structure was stabilized in samples after appropriate annealing, shifts of Raman peak positions after such treatments revealed the occurrence of symmetry distortions in the local structure of the monoclinic phase. -- Graphical abstract: Art Work - BiVO{sub 4} Synthesis and Structures. Highlights: Black-Right-Pointing-Pointer Synthesis by ball-milling of original nanostructures of BiVO{sub 4}. Black-Right-Pointing-Pointer Stabilizing a monoclinic BiVO{sub 4} polytype with nanoparticle sizes about 20 nm. Black-Right-Pointing-Pointer Investigations of annealing effects on structures, vibration and optical features.

  5. Properties of VO2 Films Sputter-Deposited from V2O5 Target

    Science.gov (United States)

    Tsai, Kuang-Yue; Chin, Tsung-Shune; Shieh, Han-Ping D.

    2003-07-01

    Rutile VO2 is a thermochromic material that exhibits a reversible metal-insulator phase transition upon thermal cycling. A new deposition process of rutile VO2 from a V2O5 target was developed using reactive oxygen instead of hydrogen. Adjusting the substrate temperature and the oxygen flow ratio changes the compositions and phases of the as-deposited films into rutile VO2 under optimum deposition conditions on the Si and thick glass substrates. Crystalline phases analyzed by X-ray diffraction shows the relationship among V4O9, V6O13, and VO2 films prepared under different deposition conditions. Analysis by AFM shows that VO2 films grown at higher substrate temperatures have larger grain size. The optical switching property of VO2 was measured at a wavelength of 1.5 ?m and transition temperature around 45C was also measured. Inhomogeneity and the strained structure of the film are suggested to be the reasons of transition temperature lower than typical reported value because the impurity in the target is too low to be detected quantatively by ICP.

  6. Formation mechanism of the VO2 polycrystalline film prepared by modified ion-beam enhanced deposition

    Science.gov (United States)

    Li, Jinhua; Yuan, Ningyi

    2004-12-01

    A new method of modified Ion Beam Enhanced Deposition (IBED) was designed to form VO2 polycrystalline film with good properties. While argon ion beam sputtered V2O5 powder target to deposit vanadium oxide film, a high current Ar+/H+ mixing beam with a high dose was implanted into the deposited film. The VO2 film with the Temperature Coefficient of Resistance (TCR) as high as 4%/K was obtained after subsequent appropriate annealing at the temperature above 500C. The formation mechanism of the IBED VO2 film was discussed as following: the damage effect of the argon ion beam implantation broken some of V-O bands; The deoxidization effect of implanted hydrogen reduced V2O5 to VO2. The mixing effect could make IBED film adhere to the substrate firmly. The doping effect of the implanted argon introduced stress in the film to decrease the phase transition temperature. The bombardment effect made the film more compact, decreased oxygen vacancy density, reduced the grain boundary width, and increased the TCR of the IBED VO2 polycrystalline films.

  7. Increases in .VO2max with "live high-train low" altitude training: role of ventilatory acclimatization.

    Science.gov (United States)

    Wilhite, Daniel P; Mickleborough, Timothy D; Laymon, Abigail S; Chapman, Robert F

    2013-02-01

    The purpose of this study was to estimate the percentage of the increase in whole body maximal oxygen consumption (.VO(2max)) that is accounted for by increased respiratory muscle oxygen uptake after altitude training. Six elite male distance runners (.VO(2max) = 70.6 ± 4.5 ml kg(-1) min(-1)) and one elite female distance runner (.VO(2max)) = 64.7 ml kg(-1) min(-1)) completed a 28-day "live high-train low" training intervention (living elevation, 2,150 m). Before and after altitude training, subjects ran at three submaximal speeds, and during a separate session, performed a graded exercise test to exhaustion. A regression equation derived from published data was used to estimate respiratory muscle .VO(2) (.VO(2RM)) using our ventilation (.VE) values. .VO(2RM) was also estimated retrospectively from a larger group of distance runners (n = 22). .VO(2max) significantly (p < 0.05) increased from pre- to post-altitude (196 ± 59 ml min(-1)), while (.VE) at .VO(2max) also significantly (p < 0.05) increased (13.3 ± 5.3 l min(-1)). The estimated .VO(2RM) contributed 37 % of Δ .VO(2max). The retrospective group also saw a significant increase in .VO(2max) from pre- to post-altitude (201 ± 36 ml min(-1)), along with a 10.8 ± 2.1 l min(-1) increase in (.VE), thus requiring an estimated 27 % of Δ .VO(2max) Our data suggest that a substantial portion of the improvement in .VO(2max) with chronic altitude training goes to fuel the respiratory muscles as opposed to the musculature which directly contributes to locomotion. Consequently, the time-course of decay in ventilatory acclimatization following return to sea-level may have an impact on competitive performance. PMID:22772455

  8. Influncia do estado nutricional e do VO2max nos nveis de adiponectina em homens acima de 35 anos / Influence of nutritional status and VO2max on adiponectin levels in men older than 35 years / Influencia del Estado Nutricional y del VO2max en los Niveles de Adiponectina en Hombres que superan los 35 Aos

    Scientific Electronic Library Online (English)

    Eduardo Camillo, Martinez; Macos de S Rego, Fortes; Luiz Antnio dos, Anjos.

    2011-06-01

    Full Text Available FUNDAMENTO: A adiponectina considerada importante fator na patognese das doenas cardiovasculares e metablicas, por suas propriedades antiaterognicas e antiinflamatrias. Poucos estudos, entretanto, sugerem a existncia de relao direta entre os nveis de adiponectina e os nveis de condiciona [...] mento cardiorrespiratrio e atividade fsica. OBJETIVO: Verificar a influncia do estado nutricional e do condicionamento cardiorrespiratrio nos nveis plasmticos de adiponectina em homens adultos. MTODOS: Foram avaliados 250 sujeitos, homens, todos militares da ativa do Exrcito Brasileiro (42,6 4,8 anos). Foram mensurados os nveis plasmticos de adiponectina, massa corporal, estatura, circunferncia da cintura (CC), percentual de gordura por pesagem hidrosttica e VO2max por ergoespirometria. Um questionrio foi utilizado para obter as caractersticas do treinamento fsico realizado pelos sujeitos. RESULTADOS: Na amostra, 121 (48%) sujeitos apresentaram sobrepeso e 36 (14%) eram obesos. Ainda, 66 sujeitos (27%) apresentaram percentual de gordura maior que 25% e 26.7% apresentaram CC > 94 cm. Sujeitos com sobrepeso e obesidade apresentaram valores significativamente menores de adiponectina em relao aqueles com estado nutricional normal. Sujeitos no mais alto tercil de VO2max apresentaram nveis de adiponectina mais altos que os demais. Os nveis de adiponectina estiveram positivamente correlacionados com o tempo total de treinamento fsico semanal e com o VO2max e inversamente correlacionados com os valores de massa corporal, IMC e CC. A correlao dos nveis de adiponectina e do VO2max no permaneceu significante aps controlada pelo IMC e CC. CONCLUSO: Sujeitos com melhor condicionamento cardiorrespiratrio e com estado nutricional normal parecem apresentar nveis mais saudveis de adiponectina. Abstract in spanish FUNDAMENTO: La adiponectina es considerada un importante factor en la patognesis de las enfermedades cardiovasculares y metablicas, por sus propiedades antiaterognicas y antiinflamatorias. Sin embargo, hay pocos estudios que sugieran la existencia de una relacin directa entre los niveles de adip [...] onectina y los niveles de condicionamiento cardiorrespiratorio y la actividad fsica. OBJETIVO: Verificar la influencia del estado nutricional y del condicionamiento cardiorrespiratorio en los niveles plasmticos de adiponectina en hombres adultos. MTODOS: Se evaluaron 250 individuos hombres, todos militares en activo del Ejrcito Brasileo (42.6 4.8 aos). Se midieron los niveles plasmticos de adiponectina, masa corporal, altura, circunferencia de la cintura (CC), porcentaje de grasa corporal por peso hidrosttico y condicionamiento cardiorespiratorio por ergoespirometria. Un cuestionario se us para obtener las caractersticas del entrenamiento fsico realizado por los individuos. RESULTADOS: En la muestra, 121 (48%), de los individuos presentaron sobrepeso y 36 (14%) eran obesos. Adems, 66 individuos (27%), presentaron un porcentaje de grasa corporal mayor que el 25%, y el 26,7% presentaron CC > 94 cm. Los individuos con sobrepeso y obesidad presentaron valores significativamente menores de adiponectina con relacin a los que tenan un estado nutricional normal. Los individuos con el ms elevado tercil de condicionamiento cardiorespiratorio, presentaron niveles de adiponectina ms altos que los dems. Los niveles de adiponectina quedaron positivamente correlacionados con el tiempo total de entrenamiento fsico semanal y con el condicionamiento cardiorespiratorio, e inversamente correlacionados con los valores de masa corporal, IMC y CC. La correlacin de los niveles de adiponectina y del condicionamiento cardiorespiratorio no permanecieron significativos despus del control del IMC y CC. CONCLUSIN: Los individuos con un mejor condicionamiento cardiorrespiratorio y con un estado nutricional normal parecen presentar niveles ms sanos de adiponectina. Abstract in english BACKGROUND: Adiponectin is consid

  9. 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 (β-1,6 y β-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 (β-1,6 and β-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.

  10. Bioadsorción de Cromo (VI en Solución Acuosa por la Biomasa Celular de Cryptococcus neoformans y Helminthosporium sp Biosorption of Chromium (VI from Aqueous Solutions by Fungal Biomass of Cryptococcus neoformans and Helminthosporium sp

    Directory of Open Access Journals (Sweden)

    I. Acosta

    2005-01-01

    Full Text Available Se determinó la bioadsorción de Cromo (VI en solución por la biomasa celular de la levadura capsulada Cryptococcus neoformans y del hongo micelial Helminthosporium sp, por el método colorimétrico de la difenilcarbazida. La biomasa de C. neoformans fue más eficiente en la remoción de Cromo (VI en solución (98% que la de Helminthosporium sp (65%. La mayor bioadsorción para C. neoformans fue a pH=2.0 +/- 0.2, mientras que para Helminthosporium sp fue a pH=4.0 +/- 0.2, ambas a 28oC durante 24 horas con 0.2 mg/L de biomasa celular. Se concluye que las biomasas fúngicas remueven eficientemente Cromo (VI en solución y pueden utilizarse para descontaminar nichos acuáticos contaminados con este metal.A determination was made on the biosorption of dissolved Chromium (VI using cellular biomass of the encapsulated yeast Cryptococcus neoformans and the mycelial fungus Helminthosporium sp. using a diphenylcarbazide colorimetric method. The C. neoformans biomass was more efficient in removing Chromium (VI from solution (98% than the Helminthosporium sp. (65%. The highest biosorption for C. neoformans was at pH 2.0 + 0.02, while for Helminthosporium sp this occurred at pH 4.0 + 0.2 , both at 28°C for 24 h employing 0.2 mg/L of cellular biomass. It is concluded that the fungal biomasses efficiently removed Chromium (VI from solution and could be used for decontamination of aquatic habitats polluted with this metal.

  11. The Gaia Archive at ESAC: a VO-inside archive

    Science.gov (United States)

    Gonzalez-Nunez, J.

    2015-12-01

    The ESDC (ESAC Science Data Center) is one of the active members of the IVOA (International Virtual Observatory Alliance) that have defined a set of standards, libraries and concepts that allows to create flexible,scalable and interoperable architectures on the data archives development. In the case of astronomy science that involves the use of big catalogues, as in Gaia or Euclid, TAP, UWS and VOSpace standards can be used to create an architecture that allows the explotation of this valuable data from the community. Also, new challenges arise like the implementation of the new paradigm "move code close to the data", what can be partially obtained by the extension of the protocols (TAP+, UWS+, etc) or the languages (ADQL). We explain how we have used VO standards and libraries for the Gaia Archive that, not only have producing an open and interoperable archive but, also, minimizing the developement on certain areas. Also we will explain how we have extended these protocols and the future plans.

  12. Ab initio study of optical excitations in VO2

    Science.gov (United States)

    Coulter, John; Gali, Adam; Manousakis, Efstratios

    2014-03-01

    Motivated by recent experimental efforts to fabricate p-n junctions from transition metal oxides (TMOs) and a recent theoretical study claiming TMOs to be good absorbers and promising materials for efficient carrier multiplication, we study the optical properties of a prototypical TMO, the insulator M1 phase of vanadium dioxide (VO2), by ab initio methods. We applied the Bethe-Salpeter equations (BSE) to calculate the optical properties, starting from self-consistent GW quasi-particle energy levels and states. In contrast to expectations, the exciton binding energy obtained by BSE is in good agreement with the experiment. We find that the electron-electron interaction is very strong which makes this material promising for efficient carrier multiplication that might lead to an enhanced efficiency in photo-voltaics applications. To illustrate this more quantitatively, we calculated the impact ionization rate within the independent quasiparticle approximation, and find that the rate is significantly higher than silicon in the region of highest solar intensity, due to the strong multiple carrier excitations.

  13. Stream or Block Cipher for Securing VoIP?

    Directory of Open Access Journals (Sweden)

    Ashraf D. Elbayoumy

    2007-09-01

    Full Text Available When the network is homogeneous, choosing the cipher type for apacket telephony application is simple. It is clear that streamciphers perform better than block ciphers over landline,circuit-switched networks, since loss is negligible in thesenetworks but corruption is not. Likewise, it is also clear thatblock ciphers perform better than stream ciphers over landline,packet-switched networks, since corruption is negligible in thesenetworks but loss is not [9]. However, the choice of cipheris not so clear for a heterogeneous internetwork containing a mixof packet and circuit-switched networks. Additionally, this issuebecomes even more confounded when heterogeneous internetwork alsoconsists of wireless links. Existing encryption systems willdegrade performance in a heterogeneous internetwork because suchinternetworks have appreciable loss and corruption. Thus, theerror properties would degrade the subjective quality of thepacket telephony application. In this paper we present anexperimental results of comparing block and stream ciphers whenused to secure VoIP in terms of end-to-end delay and subjectivequality of perceived voice.We proposed a new technique, which provides automaticsynchronization of stream ciphers on a per packet basis, withoutthe overhead of an initialization vector in packet headers orwithout maintaining any state of past-encrypted data. We show thatthis technique mitigates the trade-off between subjective qualityand confidentiality.

  14. Transport phenomena in SrVO3 thin films

    Science.gov (United States)

    Gu, Man; Wolf, Stuart; Lu, Jiwei; University of Virginia Team

    2013-03-01

    Bulk SrVO3 (SVO) with a 3d1 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 T2 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.

  15. VO-KOREL: A Fourier disentangling service of Virtual Observatory

    CERN Document Server

    koda, 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...

  16. Influência do estado nutricional e do VO2max nos níveis de adiponectina em homens acima de 35 anos

    Directory of Open Access Journals (Sweden)

    Eduardo Camillo Martinez

    2011-06-01

    Full Text Available FUNDAMENTO: A adiponectina é considerada importante fator na patogênese das doenças cardiovasculares e metabólicas, por suas propriedades antiaterogênicas e antiinflamatórias. Poucos estudos, entretanto, sugerem a existência de relação direta entre os níveis de adiponectina e os níveis de condicionamento cardiorrespiratório e atividade física. OBJETIVO: Verificar a influência do estado nutricional e do condicionamento cardiorrespiratório nos níveis plasmáticos de adiponectina em homens adultos. MÉTODOS: Foram avaliados 250 sujeitos, homens, todos militares da ativa do Exército Brasileiro (42,6 ± 4,8 anos. Foram mensurados os níveis plasmáticos de adiponectina, massa corporal, estatura, circunferência da cintura (CC, percentual de gordura por pesagem hidrostática e VO2max por ergoespirometria. Um questionário foi utilizado para obter as características do treinamento físico realizado pelos sujeitos. RESULTADOS: Na amostra, 121 (48% sujeitos apresentaram sobrepeso e 36 (14% eram obesos. Ainda, 66 sujeitos (27% apresentaram percentual de gordura maior que 25% e 26.7% apresentaram CC > 94 cm. Sujeitos com sobrepeso e obesidade apresentaram valores significativamente menores de adiponectina em relação aqueles com estado nutricional normal. Sujeitos no mais alto tercil de VO2max apresentaram níveis de adiponectina mais altos que os demais. Os níveis de adiponectina estiveram positivamente correlacionados com o tempo total de treinamento físico semanal e com o VO2max e inversamente correlacionados com os valores de massa corporal, IMC e CC. A correlação dos níveis de adiponectina e do VO2max não permaneceu significante após controlada pelo IMC e CC. CONCLUSÃO: Sujeitos com melhor condicionamento cardiorrespiratório e com estado nutricional normal parecem apresentar níveis mais saudáveis de adiponectina.

  17. NASICON-type Na3V2(PO43

    Directory of Open Access Journals (Sweden)

    Igor V. Zatovsky

    2010-02-01

    Full Text Available Single crystals of the title compound, trisodium divanadium(III tris(orthophosphate, were grown from a self-flux in the system Na4P2O7–NaVP2O7. Na3V2(PO43 belongs to the family of NASICON-related structures and is built up from isolated [VO6] octahedra (3. symmetry and [PO4] tetrahedra (.2 symmetry interlinked via corners to establish the framework anion [V2(PO43]3−. The two independent Na+ cations are partially occupied [site-occupancy factors = 0.805 (18 and 0.731 (7] and are located in channels with two different oxygen environments, viz sixfold coordination for the first (overline{3}. symmetry and eightfold for the second (.2 symmetry Na+ cation.

  18. Experimental numerical study utilizing CFD in a stratified gasifier operating with biomass; Estudio numerico experimental de un gasificador estratificado que opera con biomasa, utilizando CFD

    Energy Technology Data Exchange (ETDEWEB)

    Rogel Ramirez, Alejandro

    2007-07-01

    The central idea behind this work is the developing of a numeric-experimental model, useful to optimize the biomass stratified gasifier design. Firstly, model validation will be carried up by comparison with reference experimental data available. This study describes a 1-D + 2-D numerical model used to simulate the gasification of pine wood pellets in a stratified downdraft gasifier whereby Eulerian conservation equations are solved for particle and gas phase components, velocities and specific enthalpies. The model takes into account the biomass particle process such as heating up, drying, primary pyrolysis of biomass, secondary pyrolysis of tar, homogeneous reactions and heterogeneous combustion/gasification reactions, and particle size change. This CFD model can be used to predict temperature profiles, gas composition, producer gas lower heating value, and carbon conversion efficiency, and the reactor performance when operating parameters and feed properties are changed. The standard {kappa}-{epsilon} and RNG {kappa}-{epsilon} models were used to simulate the turbulent flow conditions. [Spanish] La idea central del presente trabajo es el desarrollo de un modelo numerico- experimental, para optimizar el diseno de gasificadores estratificados de biomasa. Primeramente, el modelo sera validado utilizando datos experimentales disponibles en la literatura. Este estudio describe un modelo numerico 1-D+2-D, utilizado para simular la gasificacion de 'pelets' de madera de pino en un gasificador estratificado de flujos paralelos, en el que se resuelven ecuaciones de conservacion Eulerianas para los componentes de la fase gaseosa, la fase solida, velocidades y entalpias especificas. El modelo considera procesos como: calentamiento, secado de la biomasa, pirolisis primaria de la madera, pirolisis secundaria de los alquitranes, reacciones homogeneas, reacciones heterogeneas de combustion/gasificacion y cambio en el tamano de la particula. Este modelo CFD puede ser utilizado para predecir perfiles de temperatura, composicion del gas, poder calorifico del syngas, eficiencia en la conversion del carbon y el comportamiento del reactor cuando los parametros de operacion y las propiedades de la alimentacion son cambiadas. El modelo estandar de turbulencia {kappa}-{epsilon} y el modelo RNG {kappa}-{epsilon}, se utilizan para la simulacion del flujo turbulento.

  19. 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.

  20. NASICON-type Na3V2(PO4)3

    OpenAIRE

    Zatovsky, Igor V.

    2010-01-01

    Single crystals of the title compound, trisodium divanadium(III) tris(orthophosphate), were grown from a self-flux in the system Na4P2O7–NaVP2O7. Na3V2(PO4)3 belongs to the family of NASICON-related structures and is built up from isolated [VO6] octahedra (3. symmetry) and [PO4] tetrahedra (.2 symmetry) interlinked via corners to establish the framework anion [V2(PO4)3]3−. The two independent Na+ cations are partially occupied [site-occupancy factors = 0.805 (18)...