WorldWideScience

Sample records for cao k2o mgo

  1. EFFECT OF MgO ON THE COMPOSITION AND PROPERTIES OF BELITE-BARIUM CALCIUM SULPHOALUMINATE CEMENT IN THE PRESENCE OF Na2O AND K2O

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2015-06-01

    Full Text Available The purpose of this study is to explore the effect of MgO (1 - 9 wt. % on the composition and properties of belite-barium calcium sulphoaluminate cement with additions of Na2O and K2O. The results show that 1 - 5 wt. % content of MgO can stabilize crystal types of M3-C3S, R-C3S and β-C2S. Moreover, MgO can promote the formation of C3S and C4AF, but has little effect on the formation of C2.75B1.25A3$ and C3A. The C3A/C4AF ratio is reduced by 22 % at 5 wt. % MgO, which indicates that appropriate MgO can decrease the liquid viscosity. In the presence of Na2O and K2O, the highest limit of incorporated amount of MgO is about 3 wt. %, which is higher than that in Portland cement clinker of 2 wt. %. Besides, MgO favors the formation of small C3S crystals in size of 4 - 20 μm. MgO enhances the hydration rate and mechanical property of cement at an optimal dosage (1 - 5 wt. %, beyond which an adverse effect could be resulted. At a MgO dosage of 5 wt. %, the compressive strengths of the cement at 1, 3, 7 and 28 days are 15.8, 39.3, 68.6 and 97.3 MPa, which increases by 116 %, 17 %, 10 % and 6 % respectively compared to the cement without MgO dopant. This study could lead to the effective use of magnesia-rich limestone in industrial production of belite-barium calcium sulphoaluminate cement.

  2. Correlation effects in MgO and CaO Cohesive energies and lattice constants

    CERN Document Server

    Doll, K; Stoll, H; Doll, Klaus; Dolg, Michael; Stoll, Hermann

    1996-01-01

    A recently proposed computational scheme based on local increments has been applied to the calculation of correlation contributions to the cohesive energy of the CaO crystal. Using ab-initio quantum chemical methods for evaluating individual increments, we obtain 80% of the difference between the experimental and Hartree-Fock cohesive energies. Lattice constants corrected for correlation effects deviate by less than 1% from experimental values, in the case of MgO and CaO.

  3. CAOS

    DEFF Research Database (Denmark)

    Erdman Thomsen, Hanne; Madsen, Bodil Nistrup

    2011-01-01

    This paper presents some principles of terminological ontologies implemented in the prototype that has been developed in the research project CAOS - Computer-Aided Ontology Structuring. Furthermore, some issues that have to be faced to further develop facilities for automatic consistency checking...... and automatic changes to ontologies, are discussed. The presentation will illustrate central facilities of the current version of the CAOS prototype, which is interactive and presupposes an end-user with a background in terminology rather than in formal ontology....

  4. Study of solid state interactions in the systems ZnFe2O4 - CaO, ZnFe2O4 - MgO and zinc cake with CaO and MgO

    Directory of Open Access Journals (Sweden)

    Peltekov A.B.

    2013-01-01

    Full Text Available The solid state interactions of CaO and MgO with synthetic and industrial ZnFe2O4 (in zinc cake have been studied using chemical, XRD analysis and Mössbauer spectroscopy. The exchange reactions in the systems ZnFe2O4 - CaO and ZnFe2O4 - MgO have been investigated in the range of 850-1200ºC and duration up to 180 min. It has been established that Ca2+ and Mg2+ ions exchange Zn2+ in ferrite partially and the solubility of zinc in a 7% sulfuric acid solution increases. The possibilities for utilization of the obtained results in zinc hydrometallurgy have been discussed.

  5. Theoretical study on influence of CaO and MgO on the reduction of FeO by CO

    Science.gov (United States)

    Zhong, Hong; Er, Dequan; Wen, Liangying

    2017-03-01

    Coating of CaO or MgO on the particle surface can prevent the sticking among iron ore particles effectively during fluidization process. However, CaO and MgO promote the formation of iron whiskers at high temperature, leading to the catastrophic defluidization. The density functional theory (DFT) calculations were implemented to investigate the influence of CaO and MgO on reduction of FeO/Fe2O2 by CO. Our results show that the CO molecule tends to bind to FeO/Fe2O2 on CaO(100) and MgO(100) surfaces through newly formed C-Fe and Csbnd O bonds. The CaO(100) surface will accelerate the reduction reactions which occur on it, in particular, in the initial stage of reactions, however, will slow down the reactions in the posterior stage. For the MgO(100) surface, the reduction reactions which occur on it will be promoted. The positive roles displayed by CaO and MgO in promoting the reduction of FeO by CO accelerate the precipitation of fresh iron and therefore, leading to the formation of iron whiskers.

  6. Thermal and catalytic cracking of ethylene in presence of CaO, MgO, zeolite and calcined dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Taralas, G.; Sjoestroem, K.; Jaeraas, S.; Bjoernbom, E. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Technology

    1993-12-31

    The subject of the present work is to study the effect of catalysts such as calcined dolomite (CaO.MgO), CaO (quicklime), MgO and Zeolite (EKZ-4) on the cracking of ethylene in the presence and absence of steam. N-heptane, toluene, naphthalene, thiophene have been some suitable model compounds for studies of the thermal and catalytic decomposition of tar. Previous results showed that the reaction scheme of the thermal decomposition of n-heptane was consistent with the high yield of ethylene observed in thermal decomposition of n-heptane. The effect of the reactor wall and the ferric impurities in the dolomite are also subjects of the research in this study. The results may also throw some additional light on the nature of the gas-phase thermal and catalytic reactions occurring in the use of dolomite as tar cracking catalysts. 28 refs

  7. Biodiesel Production From the Microalgae Nannochloropsis by Microwave Using CaO and MgO Catalysts

    Directory of Open Access Journals (Sweden)

    Herman Hindarso

    2015-02-01

    Full Text Available The needs of world petroleum are increased; in contrast, the fuel productions are getting decreased. Therefore, it has lead to the search for bio-fuel as an alternative energy. There are several different types of biofuel, such as biodiesel, ethanol, bioalcohol, and biogas. Biodiesel is typically made by chemically reacting lipids from a vegetable oil or animal fat with an alcohol producing fatty acid esters, such as methyl or ethyl ester. The present study aimed to study the effect of temperature (50, 60 and 65°C, reaction time (1 to 5 minutes dan types of catalyst (CaO dan MgO of 1 and 3 % in the production of biodiesel from microalgae by the transesterification process using microwave methods. It also studied the characteristics of biodiesel which had the greatest yield in the present study, i.e. flash point, cetane number, density, viscosity, and FAME. The greatest yield was 99.35% and obtained with combination of 3% MgO catalyst quantity at temperature of 60°C, in 3 minutes reaction time. At this process conditions, the biodiesel has a flash point of 122°C, cetane number of 55, density of  0.89, viscosity of 5 cP and FAME of 75.12 %.

  8. Ceramsite obtained from water and wastewater sludge and its characteristics affected by Fe2O3, CaO, and MgO.

    Science.gov (United States)

    Zou, J L; Xu, G R; Li, G B

    2009-06-15

    To solve the disposal problems of residual sludges, wastewater treatment sludge (WWTS) and drinking-water treatment sludge (DWTS) were tested as components for producing ceramsite. Fe(2)O(3), CaO, and MgO were the major basic oxides in WWTS and DWTS, so their effect on characteristics of ceramsite was also investigated to optimize the process. Results show that WWTS and DWTS can be utilized for producing ceramsite with optimal contents of Fe(2)O(3), CaO, and MgO ranging 5-8%, 2.75-7%, and 1.6-4%, respectively. Ceramsite within the optimal Fe(2)O(3), CaO, and MgO contents ranges was characterized using thermal analysis, X-ray diffraction (XRD), morphological structures analyses, and compressive strength measurements. Higher strength ceramsite with more complex crystalline phases and fewer pores can be obtained at 6%needed ions for producing electrical neutrality of silicate networks. Ceramsite characteristics are not dramatically influenced by MgO because Mg(2+) cannot destroy the unity of crystalline structures. This revolutionary technology of utilization of WWTS and DWTS can produce high performance ceramsite thus reducing costs of sludge disposal, in accordance with the concept of sustainable development.

  9. Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO.

    Science.gov (United States)

    Kim, Dong-Ae; Abo-Mosallam, Hany; Lee, Hye-Young; Lee, Jung-Hwan; Kim, Hae-Won; Lee, Hae-Hyoung

    2015-01-01

    Some weaknesses of conventional glass ionomer cement (GIC) as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved.Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements.Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol%) of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitrorat dental pulp stem cells (rDPSCs) viability were examined for the prepared GICs and compared to a commercial GIC.Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min) specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05) and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs.Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials.

  10. Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO

    Directory of Open Access Journals (Sweden)

    Dong-Ae KIM

    2015-08-01

    Full Text Available AbstractSome weaknesses of conventional glass ionomer cement (GIC as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved.Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements.Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol% of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitrorat dental pulp stem cells (rDPSCs viability were examined for the prepared GICs and compared to a commercial GIC.Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05 and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs.Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials.

  11. Effects of CaO, Al2O3 and MgO on liquidus temperatures of copper smelting and converting slags under controlled oxygen partial pressures

    Directory of Open Access Journals (Sweden)

    Zhao B.

    2013-01-01

    Full Text Available Phase equilibria of silicate slags relevant to the copper smelting/converting operations have been experimentally studied over a wide range of slag compositions, temperatures and atmospheric conditions. Selected systems are of industrial interest and fill the gaps in fundamental information required to systematically characterise and describe copper slag chemistry. The experimental procedures include equilibration of synthetic slag at high temperatures, rapid quenching of resulting phases, and accurate measurement of phase compositions using electron probe X-ray microanalysis (EPMA. The effects of CaO, Al2O3 and MgO on the phase equilibria of this slag system have been experimentally investigated in the temperature range 1200 to 1300 oC and oxygen partial pressures between 10-5 and 10-9 atm. It was found that spinel and silica are major primary phases in the composition range related to copper smelting/converting slags. In addition, olivine, diopside and pyroxene also appear at certain conditions. The presence of CaO, MgO and Al2O3 in the slag increases the spinel liquidus and decreases the silica liquidus. Liquidus temperatures in silica primary phase field are not sensitive to Po2; Liquidus temperatures in spinel primary phase field increase with increasing Po2. At 1300 oC and low Po2, the spinel (Fe2+,Mg2+O.(Al3+,Fe3+ primary phase field can be replaced by wustite (Fe2+,Mg2+O.

  12. Investigations of the efficiency of CaO and MgO swelling cements for deep wells. Untersuchungen zur Wirksamkeit von CaO- und MgO-Quellzementen fuer Tiefbohrungen; Abschlussbericht zur Vorphase des DGMK-Projektes 444

    Energy Technology Data Exchange (ETDEWEB)

    Ghofrani, R.; Plack, H.

    1993-02-01

    The problem of gas tightness in annular cementing of deep wells has not been comprehensively solved in conformance with present demands. It is known from practical experience, for example, that leakage may occur in cementation over short distances. Besides possible cementing failures, the problems of gas migration are also aggravated by the setting and hardening behavior of hydraulic cements and the resulting hydration volume reduction. Swelling cements, which show a real expansion of their outer dimensions, can help to solve the present problems by filling up existing void spaces in the annulus and improving the bonding at the formation/cement and cement/pipe interfaces. This applies especially to the cementing of horizontal wells, where cavities form preferentially at the top because of gravity and thus also can result in the creation of long leak channels. The object of the present work was the ascertainment of the efficiency in principle for swelling cements based on CaO and MgO additives under simulated borehole conditions. Besides the usual characteristics of cement slurries (rheological parameters, thickening time, filtrate loss) and cement stones (compressive strength, shear bond strength, permeability), special emphasis has been placed on the swelling behavior (matrix expansion, beginning and duration of the swelling phase) of such formulations. Specialized equipment has been developed and constructed for continuous measurements of the swelling behavior. With CaO cements, real expansion by up to 10 percent has been demonstrated under hydrostatic pressures up to 120 MPa. The swelling behavior depends on the timing between hydration rate of the swelling additive and the degree of hydration of the structure-forming cement. Hydration of the swelling additive generally results in increased porosity of the cement stone. However, restrained expansion led to a reduction in pore size.

  13. First-principles calculations of typical anisotropic cubic and hexagonal structures and homogenized moduli estimation based on the Y-parameter: Application to CaO, MgO, CH and Calcite CaCO3

    Science.gov (United States)

    Fu, Jia; Bernard, Fabrice; Kamali-Bernard, Siham

    2017-02-01

    X-ray method to test the material properties and to obtain elastic constants is commonly based on the Reuss model and Kroner model. Y parameter has been turned out to be an effective method to estimate elastic properties of polycrystalline material. Since Y-parameters of cubic polycrystalline material based on the certain uniform stress (Reuss model) has not been given, our work aims to complete this part of the theoretical analysis, which can effectively compare elastic constants measured by the X-ray diffraction method. The structural and the elastic properties of cubic structures (CaO and MgO) and hexagonal structures (CH and Calcite CaCO3) are investigated by the density functional theory method. And then the credibility of Y parameters for determing elastic moduli of cubic structures is proved and elastic properties in typical crystallographic planes of [100], [110] and [111] are also calculated. Meanwhile, Young's moduli of CH and Calcite structure are 58.08 GPa and 84.549 GPa, which are all close to references. Elastic properties of cubic and hexagonal structures under various pressures are calculated and the surface constructions of elastic moduli are drawn, showing the anisotropy at various directions. The crystal structure investigated in this work are typical of some primary or secondary components of Hardened Cements Pastes and their homogenized elastic properties are needed in a hierarchical multi-scale modeling, such as the one developed by some of the authors of this paper.

  14. In vitro mineralization of a glass-ceramic of the MgO-3CaO x P2O5-SiO2 system: wettability studies.

    Science.gov (United States)

    Serro, A P; Fernandes, A C; Saramago, B; Fernandes, M H V

    2002-07-01

    The calcium phosphate deposition on the surface of a bioactive glass-ceramic of the MgO-3CaO. P(2)O(5)-SiO(2) system during a 1-week immersion in biological model fluids, was investigated through wettability studies. Two model fluids with chemical composition similar to the human blood plasma were tested: Hanks' balanced salt solution (HBSS) and a simulated body fluid (SBF) with a higher calcium content. The effect of the presence of albumin, both in solution or previously adsorbed to the surface, was assessed. The behavior observed using two SBF solutions prepared with and without TRIS buffer was compared. The surface free energy of the glass-ceramic samples was determined, before and after immersion, and dynamic contact angle analysis was performed using the biological model fluids as scanning liquids. Scanning electron microscope observations and x-ray photoelectron spectroscopy (XPS) analysis were performed to complement the wettability studies. The experimental results led to the conclusion that the precipitation of a calcium phosphate film in HBSS occurred mainly when the immersion solution was renewed daily or in the presence of adsorbed albumin. In SBF, the addition of TRIS buffer seemed to inhibit the formation of the calcium phosphate film.

  15. Effect of Strong Basic Oxide (Li2O, Na2O, K2O and BaO) on Property of CaO-Based Flux

    Institute of Scientific and Technical Information of China (English)

    LI Gui-rong

    2003-01-01

    It is found that strong basic oxides including Li2O, Na2O, K2O and BaO, which are used to replace a part of CaO in CaO-based fluxes, can lower the melting point and the viscosity and enhance the dephosphorizing ability. The mechanism was analysed and the addition of Li2O to CaO-based fluxes was recommended.

  16. Quaternary equilibrium diagrams ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}). A powerful tool for the development of new materials by reaction sintering; Diagramas de equilibrio cuaternarios ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}- (CaO, MgO, TiO{sub 2}). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterizacion reactiva

    Energy Technology Data Exchange (ETDEWEB)

    Moya, J. S.; Bartolome, J. F.; Pena, P.

    2011-07-01

    In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}) multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported. (Author) 42 refs.

  17. Diagramas de equilibrio cuaternarios ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    OpenAIRE

    Moya, J. S.; Bartolomé, J. F.; Peña, P.

    2011-01-01

    En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el ...

  18. Solubility of BaS in BaO-BaF2 slag and the Influence of FeOx, SiO2, Cr2O3, BaCI2, CaO, and MgO on the sulfide capacity of this system

    Science.gov (United States)

    Rachev, Ivan P.; Tsukihashi, Fumitaka; Sano, Nobuo

    1992-03-01

    The influence of SiO2, FeOx, Cr2O3, BaCl2, CaO, and MgO on the sulfide capacity of the BaO-BaF2 system was measured at 1473 K, using a gas-slag-metal equilibration technique. It was found that the substitution of BaF2 by SiO2, FeOx, Cr2O3, and BaCl2 decreases the sulfide capacity of the BaO-BaF2 system. Similar results were obtained for the carbonate capacity. The CaO-saturated BaO-BaF2 flux, however, was found to have slightly higher sulfide and carbonate capacities than the pure BaO-BaF2 flux. The solubility of CaO increased with increasing BaF2 content and was 18 mol pet in BaF2 at 1473 K. The solubility of MgO in the BaO-BaF2 system at the same temperature is very low, and it has no effect on the sulfide and carbonate capacities. The solubility of BaS in the BaO-BaF2 system was also measured at 1473 K and had its maximum for the slag containing 40 mass pet BaO. The activity of BaO in the system was calculated from those data.

  19. Revisiting Cao Xueqin Museum

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    A Dream of Red Mansions is known by all Chinese. Its author Cao Xueqin spent his later years writing the novel at the foot of Fragrant Hills, in a western suburb of Beijing. In 1984, Cao Xueqin Museum was built there, at the site of the Man nationality residential area during the Qing Dynasty (1644-1911 ), adding a cultural scenic spot. I first visited the Cao Xueqin Museum in the spring soon after it opened. At that time, few people knew

  20. K2O/SBA-15的制备及其催化性能研究%Preparation and catalytic performance of mesoporous sieve catalyst K2O/SBA-15

    Institute of Scientific and Technical Information of China (English)

    崔晓燕; 沈健

    2011-01-01

    When potassium which was loaded to mesoporous sieve SBA-15 was calcined, K2O/SBA-15 as the solid base catalyst was synthesized. The synthesis of N-butyl acrylate was the probe reaction. The active value of K2O/SBA-15 catalyst has been carried on the transesterification in the inter mittent reactor.The results showed K2O/SBA-15 catalyst had the best catalytic active when the loaded amount of K2O added to 2%%以介孔分子筛SBA-15为载体,负载KNO3后焙烧制得K2O/SBA-15固体碱催化剂,以合成丙烯酸正丁酯的酯交换反应为探针反应,在间歇式反应釜中对K2O/SBA-15催化剂进行催化活性评价.结果表明,当K2O负载量为2%,K2O/SBA-15催化剂对此酯交换反应的催化活性最高.

  1. CAOS-CMOS camera.

    Science.gov (United States)

    Riza, Nabeel A; La Torre, Juan Pablo; Amin, M Junaid

    2016-06-13

    Proposed and experimentally demonstrated is the CAOS-CMOS camera design that combines the coded access optical sensor (CAOS) imager platform with the CMOS multi-pixel optical sensor. The unique CAOS-CMOS camera engages the classic CMOS sensor light staring mode with the time-frequency-space agile pixel CAOS imager mode within one programmable optical unit to realize a high dynamic range imager for extreme light contrast conditions. The experimentally demonstrated CAOS-CMOS camera is built using a digital micromirror device, a silicon point-photo-detector with a variable gain amplifier, and a silicon CMOS sensor with a maximum rated 51.3 dB dynamic range. White light imaging of three different brightness simultaneously viewed targets, that is not possible by the CMOS sensor, is achieved by the CAOS-CMOS camera demonstrating an 82.06 dB dynamic range. Applications for the camera include industrial machine vision, welding, laser analysis, automotive, night vision, surveillance and multispectral military systems.

  2. 介孔分子筛K2O/SBA-15催化酯化反应的研究%Esterification Catalyzed by Mesoporous Sieve K2 O/SBA-15

    Institute of Scientific and Technical Information of China (English)

    崔晓燕; 沈健; 刘琤; 沈思维

    2011-01-01

    以介孔分子筛SBA-15为载体,负载KNO3后经过煅烧,制得K2O/SBA-15固体碱催化剂.通过XRD和BET对样品进行了测试分析,并对K2O/SBA-15催化合成油酸甲酯的酯化反应进行了研究.试验结果表明:当K2O负载量为2%,n(醇)∶n(酸)2∶1,反应温度180℃,反应时间4 h,催化剂用量为原料质量的5.0%时,酯化率最大达到83.61%,并且K2O/SBA-15催化剂重复使用多次仍具有较好的催化效果.%Solid base catalyst K2O/SBA-15 was prepared by loading potassium nitrate on mesoporous sieve SBA-15 and then was calcined. The samples were characterized by XRD and BET and used as catalyst in the synthesis of methyl oleate. The experimental results showed that when the loaded amount of K2O was 2% , molar ratio of methanol/oleic acid was 2:1 ,reaction temperature was 180 ℃ ,reaction time was 4 h and the ratio of catalyst to raw material was 5% ( weight ratio), the esterification rate was 83.61%. The results also showed that K2O/SBA-15had a good catalytic effect after resued.

  3. Efeitos da fertirrigação de N e K2O na absorção de macronutrientes pela gravioleira Effects of fertirrigation of N and K2O on absorption of macronutrients by soursop crop

    Directory of Open Access Journals (Sweden)

    Roberto S. F. de H. Filho

    2006-03-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de dosagens de N e K2O via água de irrigação na absorção de macronutrientes pela cultura da gravioleira. O experimento foi realizado no campo experimental da Embrapa Meio-Norte, situado no município de Teresina, PI (05º 05' S, 42º 48' W e 74,4 m de altitude. O delineamento experimental utilizado foi por blocos casualizados, com onze tratamentos e quatro repetições, com parcela útil composta de quatro plantas. Os tratamentos consistiram na aplicação de cinco dosagens de N (20, 120, 200, 280 e 380 kg ha-1 ano-1 combinadas com cinco dosagens de K2O (30, 180, 300, 420 e 570 kg ha-1 ano-1 de acordo com o modelo da matriz experimental Plan Plueba III, além de um tratamento com dosagem zero de ambos os nutrientes. Em nenhum dos tratamentos foi encontrado deficiência de N, K, Mg, S e P nas folhas da gravioleira. As dosagens de N, bem como as suas interações com as dosagens de K2O, não proporcionaram efeito significativo sobre os teores dos macronutrientes nas folhas da gravioleira. As dosagens de K2O influenciaram os teores dos macronutrientes Ca, K e Mg nas folhas da gravioleira.The objetive of this work was to evaluate the effect of doses of N and K2O through irrigation water on the absorption of macronutrients by soursop cultivation. The study was conducted at the experimental field of Embrapa - North, in Teresina, in the State of Piauí, Brazil (5º 05' S, 42º and 48' W. The experimental design was completely randomized blocks with eleven treatments and four repetitions. The treatments consisted in the application of five doses of N (20, 120, 200, 280 and 380 kg ha-1 year-1 combined with five doses of K2O (30, 180, 300, 420 and 570 kg ha-1 year-1 in agreement with the model of experimental matrix Plan Plueba III, besides a treatment with dose zero of both nutrients. No deficiency of N, K, Mg, S, and P in the soursop leaves was found in any treatment. The doses of N did not provide

  4. Effects of M2+ (M = Ca, Sr, and Ba Addition on Crystallization and Microstructure of SiO2-MgO-Al2O3-B2O3-K2O-F Glass

    Directory of Open Access Journals (Sweden)

    Mrinmoy Garai

    2015-01-01

    Full Text Available In understanding the effect of K+ substitution by M2+ (M = Ca, Sr, and Ba on crystallization and microstructural properties of boroaluminosilicate glass system, the SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glasses were prepared by single-step melt-quenching at 1500°C. Density of base glass (2.64 g·cm−3 is found to be decreased in presence of CaO and SrO. Tg is increased by 5–10°C and Td decreased by 13–20°C on addition of M2+. The variation of Tg, Td and decrease of thermal expansion (CTE from 7.55 to 6.67–6.97 (×10−6/K, at 50–500°C in substituting K+ by M2+ are attributed to the higher field-strength of Ca2+, Sr2+, and Ba2+. Opaque mica glass-ceramics were derived from the transparent boroaluminosilicate glasses by controlled heat treatment at 1050°C (duration = 4 h; and the predominant crystalline phase was identified as fluorophlogopite (KMg3AlSi3O10F2 by XRD and FTIR study. Glass-ceramic microstructure reveals that the platelike mica flake crystals predominate in presence of K2O and CaO but restructured to smaller droplet like spherical shaped mica on addition of SrO and BaO. Wide range of CTE values (9.54–13.38 × 10−6/K at 50–800°C are obtained for such glass-ceramics. Having higher CTE value after crystallization, the CaO containing SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glass can be useful as SOFC sealing material.

  5. 介孔分子筛K2O/SBA-15催化酯交换反应研究%Study on transesterification catalyzed by mesoporous molecular sieve K2O/SBA-15

    Institute of Scientific and Technical Information of China (English)

    崔晓燕; 沈健

    2011-01-01

    The solid base catalyst K20/SBA- 15 were prepared with mesoporous molecular sieve SBA - 15 as carrier,and by supporting potassium nitrate and then calcining. The transesterification was studied for the synthesis of n - butyl acrylate from methyl acrylate and n - butanol catalyzed by K2O/SBA - 15. The results showed that when K2O loading was 2% (mass fraction) ,reaction time was 6 h,reaction temperature was 180 ℃, n ( n - butanol ) /n ( methyl acrylate) was 4 and the mass ratio of catalyst to raw material was 0.1, the best conversion of methyl acrylate could reach 64.22%.%以介孔分子筛SBA-15为载体,负载KNO3后经过焙烧,制得K2O/SBA-15固体碱催化剂.对K2O/SBA-15催化丙烯酸甲酯与正丁醇合成丙烯酸正丁酯的酯交换反应进行了研究.结果表明,当K2O负载量为2%,反应时间为6 h,反应温度为180℃,n(正丁醇)/n(丙烯酸甲酯)为4,m(催化剂)/m(原料)为0.1时,丙烯酸甲酯的转化率最大,为64.22%.

  6. FT-IR and thermoluminescence investigation of P2O5-BaO-K2O glass system

    Science.gov (United States)

    Ivascu, C.; Timar-Gabor, A.; Cozar, O.

    2013-11-01

    The 0.5P2O5ṡxBaOṡ(0.5-x)K2O glass system (0≤x≤0.5mol%) is investigated by FT-IR and thermoluminescence as a possible dosimetic material. FT-IR spectra show structural network modifications with the composition variations of the studied glasses. The predominant absorption bands are characterized by two broad peaks near 500 cm-1, two weak peaks around 740 cm-1 and three peaks in the 900-1270 cm-1 region. The shift in the position of the band assigned to asymmetric stretching of PO2- group, υas(PO2-) modes from ˜1100 cm-1 to 1085 cm-1 and the decrease in its relative intensity with the increasing of K2O content shows a network modifier role of this oxide.. Luminescence investigations show that by adding modifier oxides in the phosphate glass a dose dependent TL signals result upon irradiation. Thus P2O5-BaO-K2O glass system is a possible candidate material for dosimetry in the dose 0 - 50 Gy range.

  7. Fabrication of 45 degrees template grain boundary junctions using a CaO lift-off technique

    NARCIS (Netherlands)

    IJsselsteijn, R.P.J.; Terpstra, D.; Flokstra, J.; Rogalla, H.

    1994-01-01

    45 degrees grain boundary junctions have been made using (100) MgO substrates, a CeO2 template layer and an YBa2Cu3O7 top layer. To minimize the damage to the MgO surface, which will occur if the CeO2 is structured using ion milling, the CeO2 layer has been structured using the CaO lift-off techniqu

  8. Preparation of solid base of K2O/C and transesterification catalyzed by the catalyst%固体碱催化剂(K2 O/C)的制备及其催化酯交换反应

    Institute of Scientific and Technical Information of China (English)

    郭萍梅; 黄凤洪; 赵军英; 郑畅

    2009-01-01

    以活性炭为载体,负载K2CO3后经过煅烧,制得K2O/C固体碱催化剂,通过正交实验,得到催化剂的优化制备条件为:K2CO3与活性炭摩尔比0.04,粒径40目,煅烧温度450℃,煅烧时间3.5h,浸渍时间3h;将其应用于催化棉籽油酯交换制备生物柴油,考察了催化剂的加入量、醇油比、反应温度、反应时间、原料中水分含量等对酯交换反应的影响,得到最佳工艺参数:醇油摩尔比8∶ 1、催化剂加入量4.0%、反应时间1h.在此条件下,K2O/C的催化活性优于传统均相催化剂,重复使用多次仍具有较好的催化效果.

  9. Lateral variation of H2O/K2O ratios in Quaternary Magma of the Northeastern Japan arc

    Science.gov (United States)

    Miyagi, I.

    2012-12-01

    Water plays a fundamental role in the magma genesis beneath subduction zones. In order to estimate a spatial distribution of the density of water flux in the wedge mantle of the Northeastern Japan arc, this study examines a lateral variation of pre-eruptive bulk rock H2O/K2O contents among volcanoes located both in the frontal and in back arc settings. The analytical targets are the frontal volcanoes Nigorikawa (N42.12 E140.45), Zenikame (N41.74 E140.85), Adachi (N38.22 E140.65), and Nanashigure (N40.07 E141.11), and the back arc ones Hijiori (N38.61 E140.17) and Kanpu (N39.93 E139.88). The bulk magmatic H2O content (TH2O) is calculated from a mass balance of hydrogen isotopic ratios among three phases in a batch of magma; dissolved water in melt, excess H2O vapor, and hydrous phenocrysts such as amphiboles (Miyagi and Matsubaya, 2003). Since the amount of H2O in hydrous phenocryst is negligible, the bulk magmatic H2O content can be written as TH2O = (30 XD CD) / (15 - dT + dMW), where dMW is the measured hydrogen isotopic ratio of hydrous phenocrysts, XD is a melt fraction of magma, CD is a water concentration of the melt, and dT is hydrogen isotopic ratios of a bulk magma (assumed to be -50 per-mil). Both XD and CD are estimated from bulk rock chemistry of the sample using the MELTS program (Ghiorso and Sack, 1995). Hydrogen isotopic fractionation factors are assumed to be -15 and -30 per-mil for vapor and hydrous mineral, and vapor and silicate melt, respectively. There observed a clear difference among the H2O/K2O ratios of bulk magmas from the frontal and back arc volcanoes. For instance higher H2O/K2O wt ratios was observed in the frontal volcanoes (Nigorikawa 5.3, Zenikame 11-12, Adachi 8-10, and Nanashigure 4-18), while lower H2O/K2O wt ratios was observed in the back arc ones (Kanpu 0-2.5 and Hijiori 1.4). The lateral variation of H2O/K2O ratios infer the higher water flux through the frontal side of wedge mantle, which can be a potential cause of the

  10. The Structural Optimization System CAOS

    DEFF Research Database (Denmark)

    Rasmussen, John

    1990-01-01

    CAOS is a system for structural shape optimization. It is closely integrated in a Computer Aided Design environment and controlled entirely from the CAD-system AutoCAD. The mathematical foundation of the system is briefly presented and a description of the CAD-integration strategy is given together...

  11. Mössbauer study and magnetic properties of MgFe2O4 crystallized from the glass system B2O3/K2O/P2O5/MgO/Fe2O3

    Science.gov (United States)

    Shabrawy, S. El; Bocker, C.; Miglierini, M.; Schaaf, P.; Tzankov, D.; Georgieva, M.; Harizanova, R.; Rüssel, C.

    2017-01-01

    An iron containing magnesium borate glass with the mol% composition 51.7 B2O3/9.3 K2O /1 P2O5/27.6MgO/10.4Fe2O3was prepared by the conventional melts quenching method followed by a thermal treatment process at temperatures in the range from 530 to 604 °C.The thermally treated samples were characterized by X-ray diffraction, scanning and transmission electron microscopy. It was shown that superparamagnetic MgFe2O4 nanoparticles were formed during thermal treatment. The size of the spinel type crystals was in the range from 6 to 15 nm. Mössbauer spectra of the powdered glass ceramic samples and the extracted nanoparticles after dissolving the glass matrix in diluted acid were recorded at room temperature. The deconvolution of the spectra revealed the crystallization of two spinel phases MgFe2O4 (as a dominant phase) and superparamagnetic maghemite, γ-Fe2O3 (as a secondary phase). Room temperature magnetic measurements showed that, increasing the crystallization temperature changed the superparamagnetic behavior of the samples to ferrimagnetic behavior. The Curie temperatures of the samples were measured and showed a higher value than that of the pure bulk MgFe2O4.

  12. Thermodynamics of O, N, and S in liquid Fe equilibrated with CaO-AI2O3-MgO slags

    Science.gov (United States)

    Inoue, Ryo; Suito, Hideaki

    1994-04-01

    Nitrogen and S distribution ratios between CaO-Al2O3-MgO slags and liquid Fe were measured at 1873 K as a function of Al (or Mg, Ca) content in metal, using CaO, MgO, and A12O3 crucibles. Based on the results for the solubility product of MgO, the equilibrium constant, K Mg , for the reaction MgO = Mg + O and the first-order interaction parameter, e {O/Mg} ( e {Mg/O}), were estimated to be log K Mg = -7.8 ± 0.2 and e {O/Mg} = -190 ± 60 ( e {Mg/O} = -290 ± 90), respectively. The activities of A12O3 at the slag compositions double-saturated with CaO/MgO, MgO/ MgO A12O3, and MgO Al2O3/CaO 2A12O3 components were obtained from the S distribution ratios between slag and metal, coupled with the reported values of sulfide capacities. Nitride capacities were also estimated from the N distribution ratios and the activities of A12O3.

  13. Diffuse Reflectance Infrared Fourier Transform Study of NOx Adsorption on CGO10 Impregnated with K2O or BaO

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund; Härelind Ingelsten, H.; Kammer Hansen, Kent

    2012-01-01

    In the present work Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy is applied to study the adsorption of NOx at 300-500 °C in different atmospheres on gadolinium doped ceria (CGO), an important material in electrodes investigated for electrochemical NOx removal. Furthermore......, the effect on the NOx adsorption when adding K2O or BaO to the CGO is investigated. The DRIFT study shows mainly the presence of nitrate species at 500 °C, while at lower temperature a diversity of adsorbed NOx species exists on the CGO. Presence of O2 is shown to have a strong effect on the adsorption of NO......, but no effect on the adsorption of NO2. Addition of K2O and BaO dramatically affects the NOx adsorption and the results also show that the adsorbed NOx species are mobile and capable of changing adsorption state in the investigated temperature range....

  14. Relationship between Leucite Content and Compressive Strength of K2O-Al2O3-SiO2 System Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; QIAN Fatang; DUAN Xinglong; WU Bolin

    2009-01-01

    Relationship between leucite content and compressive strength of K2O-Al2O3-SiO2 sys-tem dental glass ceramics were investigated. 10 groups of feedstock powder with different composi-tions were treated according to the same thermal treatment system of leucite micro-crystallization reported in some primary studies. The products of each group were analyzed by X-ray diffractometer,polaring microscope and scanning electronic microscope (SEM), and then the compressive strength was tested by a material testing machine. A direct proportion was found between leucite content and the compressive strength when leucite content was less than 50 vol%, and compressive strength de-creased with the increasing of leucite micro-crystals when leucite content was more than 50vol%, The leucite content has a notable influence on the compressive strength of K2O-Al2O3-SiO2 system dental glass ceramics.

  15. Reusability and Stability Tests of Calcium Oxide Based Catalyst (K2O/CaO-ZnO for Transesterification of Soybean Oil to Biodiesel

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2016-03-01

    Full Text Available This paper was purposed for testing reusability and stability of calcium oxide-based catalyst (K2O/CaO-ZnO over transesterification reaction of soybean oil with methanol to produce biodiesel. The K2O/CaO-ZnO catalyst was synthesized by co-precipitation method of calcium and zinc nitrates followed by impregnation of potassium nitrate. The fresh and used catalysts were tested after regeneration. The catalysts were characterized by Scanning Electron Microscopy (SEM, X-ray Diffraction (XRD, and BET Surface Area in order to compare the catalyst structure between the fresh and used catalysts. The catalyst testing in transesterification proses was carried out at following operating conditions, i.e. catalyst weight of 6 wt.%, oil to methanol mole ratio of 1:15, and temperature of 60 oC. In addition, metal oxide leaching of K2O/CaO-ZnO catalyst during reaction was also tested. From the results, the catalysts exhibited high catalytic activity (80% fatty acid methyl ester (FAME yield after three-cycles of usage and acceptable reusability after regeneration. The catalyst also showed acceptable stability of catalytic activity, even after three-cycles of usage. Copyright © 2016 BCREC GROUP. All rights reserved Received: 10th November 2015; Revised: 16th January 2016; Accepted: 16th January 2016 How to Cite: Istadi, I., Mabruro, U., Kalimantini, B.A.,  Buchori, L., Anggoro, D.D. (2016. Reusability and Stability Tests of Calcium Oxide Based Catalyst (K2O/CaO-ZnO for Transesterification of Soybean Oil to Biodiesel. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 34-39. (doi:10.9767/bcrec.11.1.413.34-39 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.413.34-39

  16. Silicate liquid immiscibility in magmas and in the system K2O-FeO-AI2O3-SiO2: an example of serendipity

    Science.gov (United States)

    Roedder, E.

    1978-01-01

    The concept of silicate liquid immiscibility was invoked early in the history of petrology to explain certain pairs of compositionally divergent rocks, but. as a result of papers by Greig (Am. J. Sci. 13, 1-44, 133-154) and Bowen (The Evolution of the Igneous Rocks), it fell into disfavor for many years. The discovery of immiscibility in geologically reasonable temperature ranges and compositions in experimental work on the system K2O-FeO-Al2O3-SiO2, and of evidence for immiscibility in a variety of lunar and terrestrial rocks, has reinstated the process. Phase equilibria in the high-silica corner of the tetrahedron representing the system K2O- FeO-Al2O3-SiO2 are presented, in the form of constant FeO sections through the tetrahedron, at 10% increments. Those sections, showing the tentative relationships of the primary phase volumes, are based on 5631 quenching runs on 519 compositions, made in metallic iron containers in pure nitrogen. Thirteen crystalline compounds are involved, of which at least six show two or more crystal modifica-tions. Two separate phase volumes, in each of which two immiscible liquids, one iron-rich and the other iron-poor, are present at the liquidus. One of these volumes is entirely within the quaternary system, astride the 1:1 K2O:Al2O3 plane. No quaternary compounds as such have been found, but evidence does point toward at least partial quaternary solid solution, with rapidly lowering liquidus temperatures, from K2O??Al2O3?? 2SiO2 ('potash nepheline', kalsilite. kaliophilite) to the isostructural compound K2O??FeO??3SiO2, and from K2O??Al2O3??4SiO2 (leucite) to the isostructural compound K2O??FeO??5SiO2, Both of these series apparently involve substitution, in tetrahedral coordination. of a ferrous iron and a silicon ion for two aluminum ions. Some of the 'impurities' found in analyses of the natural phases may reflect these substitutions. As a result of the geometry of the immiscibility volume located entirely within the quaternary

  17. EFEITOS DA FERTIRRIGAÇÃO DE N E K2O NA DISTRIBUIÇÃO DO SISTEMA RADICULAR DA GRAVIOLEIRA

    Directory of Open Access Journals (Sweden)

    Waleska Martins Eloi

    2007-01-01

    Full Text Available The objective of this work was to evaluate the effect of different doses of nitrogen and potassium applied through the irrigation water by micro-sprinkler in the space distribution of the root system of the soursop (Annona muricata L., through digital images. The study was conducted at the experimental field of Embrapa - North, in Teresina - PI (05th 05 ' S and 42 and 48 ' W. The treatments consisted of the combination of five doses of nitrogen (20, 120, 200, 280 and 380 kg ha-1 year-1 with five potassium doses (30, 180, 300, 420 and 570 kg ha-1 year-1, besides the witness, applied every fifteen days. The evaluation of the length of roots was accomplished being used the software SIARCS and the results were analyzed through graphs of contour and columns. The largest concentrations of roots in relation to horizontal distance happened inside of the projection of the cup. The treatment whose doses of N and K2O were 380 kg ha-1 year-1 of N and 420 kg ha-1 year-1 of K2O it presented the best vertical profile of root distribution and it was also verified that dose high of potassium they inhibit the root development.

  18. Caos, complejidad y cardiología

    OpenAIRE

    Martínez-Lavín,Manuel

    2012-01-01

    La ciencia es una disciplina en constante evolución. La medicina moderna está basada en la ciencia. El paradigma médico vigente es lineal y reduccionista. Existe una nueva teoría general avalada por cálculos computacionales avanzados, la teoría del caos y la complejidad. Esta nueva visión probablemente modificará la práctica de la medicina. La cardiología fue una puerta de entrada de la complejidad, al campo de la medicina. El caos y los fractales son fenómenos frecuentes en la fisiología car...

  19. 超声波辅助下K2O/C催化制备纤维低聚糖脂肪酸酯表面活性剂%Ultrasonic-assisted Synthesis of Cellulosic Oligosaccharide Esters Surfactant Catalyzed by K2 O/C

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The solid base catalyst K2 O/C was prepared by the vacuum impregnation method. The orthogonal experiment was employed to optimize the preparation condition. The results indicated that the optimal reaction parameters were carbon carrier with average pore size 2. 87 nm, K2 CO3/C mass ratio 0. 5, catalyst calcination temperature 450 ℃, and calcination time 2 h. The prepared catalyst K2 O/C was adopted to catalyze the transesterification reaction of cellulosic oligosaccharide esters from cellulosic oligosaccharide and methyl oleate under ultrasonic assistance. The optimum conditions were obtained as follows: the ultrasonic frequency 20 kHz, the ultrasonic power 150 W, treatment time 15 min, the mole ratio of methyl oleate to cellulosic oligosaccharide esters 2∶1, the mass fraction of K2 O/C 5%, the reaction temperature 125 ℃, and the reaction time 2 h. Under these conditions, the yield of cellulosic oligosaccharide esters reached 85. 6%. The synthesized product has esterification degree 18. 8%, HLB 9. 89, surface tension 32. 1 mN/m, and the emulsifying ability 28. 1%. The product showed good performance on surface tension, emulsion and stability in hard water.%采用真空浸渍法制备炭基固体碱催化剂 K2 O/C,并在超声波辅助条件下,利用制备的K2 O/C催化纤维低聚糖与油酸甲酯制备纤维低聚糖脂肪酸酯表面活性剂。选取L9(34)正交试验确定制备K2 O/C催化剂的最佳条件为:炭基载体平均孔径为2.87 nm,K2 CO3与炭基载体的质量比值为0.5,真空浸渍后,450℃下煅烧2 h。考察了超声波辅助下超声波时间、超声波频率、反应温度、反应时间和催化剂用量对产品得率的影响。研究发现:在20 kHz,150 W超声功率下,将物质的量之比为2∶1的油酸甲酯和纤维低聚糖(水溶液)超声波作用15 min,形成均一稳定的乳化体系,真空条件下,移除体系中的水分后,加入占总物料量5%的K2 O/C催化剂,125℃下反应2 h,纤维低聚糖

  20. Optical Properties of K2O-Li2O-WO3-B2O3 Glasses: Evidence of Mixed Alkali Effect

    Science.gov (United States)

    Edukondalu, Avula; Sripathi, T.; Kareem Ahmmad, Shaik; Rahman, Syed; Sivakumar, K.

    2017-02-01

    Glass with compositions xK2O-(30 - x)Li2O-10WO3-60B2O3 for 0 ≤ x ≤ 30 mol.% have been prepared using the normal melt quenching technique. The optical reflection and absorption spectra were recorded at room temperature in the wavelength range 300-800 nm. From the absorption edge studies, the values of the optical band gap ( E opt) and Urbach energy (Δ E) have been evaluated. The values of E opt and Δ E vary non-linearly with composition parameter, showing the mixed alkali effect. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple Di-Domenico model.

  1. Structural investigation of V$_2$O$_5$–P$_2$O$_5$–K$_2$O glass system with antibacterial potential

    Indian Academy of Sciences (India)

    N S VEDEANU; I B COZAR; R STANESCU; R STEFAN; D VODNAR; O COZAR

    2016-06-01

    The $x$V$_2$O($1 − x$)[0.8 P$_2$O$_5$·0.2K$_2$O] glass system with $0 \\lt x \\lt 50$ mol% was prepared and the structural changes induced in these glasses by increasing the vanadium oxide content were investigated by IR and ESR spectroscopies. The dual behaviour role of V$_2$O$_5$ oxide, as network modifier (for $x\\lt 10$ mol%) and the network former ($x\\gt 20$ mol%), as a consequence of phosphate network depolymerization and P–O–V and V–O–V linkages appearance was also highlighted. The antibacterial effect of the glasses with $x \\lt 20$ mol% V$_2$O$_5$ content was tested by optical density (OD) measurements. A linear correlation between the amount of vanadium and the antibacterial effect was evidenced.

  2. Optical Properties of K2O-Li2O-WO3-B2O3 Glasses: Evidence of Mixed Alkali Effect

    Science.gov (United States)

    Edukondalu, Avula; Sripathi, T.; Kareem Ahmmad, Shaik; Rahman, Syed; Sivakumar, K.

    2016-10-01

    Glass with compositions xK2O-(30 - x)Li2O-10WO3-60B2O3 for 0 ≤ x ≤ 30 mol.% have been prepared using the normal melt quenching technique. The optical reflection and absorption spectra were recorded at room temperature in the wavelength range 300-800 nm. From the absorption edge studies, the values of the optical band gap (E opt) and Urbach energy (ΔE) have been evaluated. The values of E opt and ΔE vary non-linearly with composition parameter, showing the mixed alkali effect. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple Di-Domenico model.

  3. Raman, FTIR, DSC, EPR and optical properties of B2O3-K2O-ZnO-Li2Oglass system doped with Cu2+ ions

    Directory of Open Access Journals (Sweden)

    G. N. Devde

    2015-12-01

    Full Text Available X-ray diffraction (XRD, Raman, Fourier Transform Infrared (FTIR, Differential scanning calorimetry (DSC, Electron paramagnetic resonance (EPR and optical absorption studies on 59B2O3-10K2O-(30-xZnO-xLi2O- 1CuO glasses (where x = 0, 6, 12, 18, 24 and 30 mol% have been carried out. The amorphous nature of the glasses was confirmed using XRD and DSC measurements. The glass transition temperature (Tg of glass samples have been estimated from DSC traces and found that Tg decreases from 488 to 422 oC with the progressive substitution of Li2O content in the place of ZnO content. Almost all of the glass samples in the composition 59B2O3-10K2O-(30-xZnO-xLi2O-1CuO (0 ≤ x ≤ 30 mol% have the thermal stability (ΔT more than 100 oC. The Raman and FTIR studies have been showed that the present glass system consists of [BO3] and [BO4] units in various borate groups. The spin-Hamiltonian parameters (SHP such as g||, g⊥, and A|| have been determined from EPR spectra and it was found that the Cu2+ ion is present in tetragonal distorted octahedral site with x2 - y2 d as the ground state. Bonding parameters and bonding symmetry of Cu2+ ions have been calculated by correlating EPR and optical data and were found to be composition dependent.

  4. Internet desde la perspectiva del caos

    OpenAIRE

    FANNY DE HIMMELSTERN

    2000-01-01

    En este artículo, la autora utiliza algunas cateogorías de la Teoria del Caos para comprender el fenómeno de internte. Según la autora, la relación entre cultura, tecnolgoía y ciencia, y el uso del internet han modificado nuestras percepciones sociales.

  5. The effect of CaF2 on thermodynamics of CaO-CaF2-SiO2(-MgO) slags

    Science.gov (United States)

    Choi, Chul-Hwan; Jo, Sung-Koo; Kim, Seon-Hyo; Lee, Kwang-Ro; Kim, Jeong-Tae

    2004-02-01

    To address the role of CaF2 in the CaO-CaF2-SiO2(-MgO) slag system employed for the production of low-pressure rotor steels, the thermodynamic aspects of the slag were investigated by equilibrating it with liquid iron at 1873 K in CaO or MgO crucibles. Presaturation of slag with an oxide block piece of CaO or MgO in a Pt crucible and application of a carbon paste to the outside of an oxide crucible were designed to prevent crucible failure during the slag-metal experiments. The liquidus isotherm and phase boundary of the preceding slag system were investigated using the slag-metal equilibria. Also, the effect of CaF2 on the sulfide capacity and the activity coefficient of Fe t O were of particular interest in controlling the sulfur level and cleanliness of low-pressure rotor steels.

  6. Study on Transesterification of Soybean Oil Catalyzed by Solid Base K2O/Zr-MCM-41%固体碱K2O/Zr-MCM-41催化大豆油酯交换反应的研究

    Institute of Scientific and Technical Information of China (English)

    张磊; 于世涛; 刘福胜; 解从霞; 曹柯

    2007-01-01

    以浸渍法制备了K2O/Zr-MCM-41固体碱催化剂,采用XRD技术对其进行表征,并以该固体碱为催化剂进行大豆油酯交换反应研究.结果表明,产品得率达到95.8%以上.且该工艺操作简单,催化剂可回收再生,整个过程无"三废"污染.

  7. Experimental Work Conducted on MgO Inundated Hydration in WIPP-Relevant Brines

    Science.gov (United States)

    Deng, H.; Xiong, Y.; Nemer, M. B.; Johnsen, S.

    2009-12-01

    Magnesium oxide (MgO) is being emplaced in the Waste Isolation Pilot Plant (WIPP) as an engineered barrier to mitigate the effect of microbial CO2 generation on actinide mobility in a postclosure repository environment. MgO will sequester CO2 and consume water in brine or water vapor in the gaseous phase. Martin Marietta (MM) MgO is currently being emplaced in the WIPP. A fractional-factorial experiment has been performed to study the inundated-hydration of MM MgO as a function of its particle size, solid-to-liquid ratio, and brine type. MgO hydration experiments have been carried out with three MgO particle sizes and two solid-to-liquid ratios in three WIPP-related brines: ERDA-6, GWB and simplified GWB. ERDA-6 is a synthetic NaCl-rich brine typical of a Castile brine reservoir below the repository. GWB is a synthetic MgCl2- and NaCl-rich brine representative of intergranular brines from the Salado Formation at or near the stratigraphic horizon of the repository. Simplified GWB contains amounts of Mg, Na, and Cl similar to those in GWB without other minor constituents. The hydration products include brucite (Mg(OH)2) and phase 5 (Mg3(OH)5Cl4H2O). In addition to phase 5, MgO hydration in GWB or simplified GWB produces brucite, whereas MgO hydrated in ERDA-6 only produces brucite. The MgO particle size has had a significant effect on the formation of hydration products: small MgO particles have hydrated before the large particles. MgO has hydrated faster in simplified GWB than in the other two brines. In ERDA-6, the solid-to-liquid ratio has affected the brine pH due to the presence of CaO (~1 wt %) as an impurity in MM MgO. GWB has sufficient dissolved Mg to buffer pH despite small amounts of CaO. Both our results and thermodynamic modeling indicate that phase-5 is the stable Mg-OH-Cl phase in Mg-Na-Cl-dominated brines with ionic strengths and chemical compositions similar to that of GWB. In contrast, phase-3 (Mg2(OH)3Cl4H2O) is the stable phase in the MgCl2

  8. The Dissolution Kinetics of MgO into CaO-MgO-Fe2O3 Slag

    Science.gov (United States)

    Wei, Ruirui; Lv, Xuewei; Yue, Zhiwen; Xiang, Shenglin

    2017-02-01

    Calcium ferrite is the main binding phase for high-basicity sinter. The production and structure of calcium ferrite greatly influence the quality of the sinter. With the change in gangue composition, MgO becomes an important factor in the generation of calcium ferrite. In this study, the rotating cylinder method was used to study the dissolution kinetics of MgO into CaO-MgO-Fe2O3 melt. The experimental variables included the temperature, the initial composition of the melt, the Fe2O3/CaO mass ratio, the rotation time, and the rotation speed. The results indicate that the dissolution rate increases with increasing dissolution time, temperature, and rotation speed but decreases with increasing MgO content and Fe2O3/CaO mass ratio in the initial slag. The dissolution rate was observed to increase and then decrease with the addition of SiO2 in the initial slag. The activation energy and diffusion coefficient for MgO dissolution were found to range from 117.31 to 234.24 kJ mol-1 and from 1.03 × 10-6 to 1.18 × 10-5 cm2 s-1, respectively. The concentration difference between the solid and liquid phases is the main driving force for dissolution, but the viscosity and magnesium ion diffusivity of the melt also affect the process.

  9. Assimilation Behavior of Calcium Ferrite and Calcium Diferrite with Sintered Al2O3 and MgO

    Science.gov (United States)

    Long, Hongming; Wu, Xuejian; Chun, Tiejun; Di, Zhanxia; Yu, Bin

    2016-10-01

    In this study, the assimilation behaviors between calcium ferrite (CF), calcium diferrite (CF2) and sintered Al2O3, and MgO were explored by an improved sessile drop technique, and the interfacial microstructure was discussed. The results indicated that the apparent contact angles of CF slag on Al2O3 and MgO substrate were 15.7 and 5.5 deg, and the apparent contact angles of CF2 slag on Al2O3 and MgO substrate were 17.9 and 7.2 deg, respectively. Namely, CF and CF2 slag were wetting well with Al2O3 and MgO substrate. The dissolution of Al2O3 substrate into the CF and CF2 slag was found to be the driving force of the wetting process. For the CF-MgO and CF2-MgO substrate systems, CaO contrarily distributed with MgO after wetting. For the CF-MgO system, after wetting, the slag was composed of CF and C2F, and most of the Fe2O3 permeated into substrate and formed two permeating layers.

  10. Influence of Basicity and MgO on Fluidity and Desulfurization Ability of High Aluminum Slag

    Science.gov (United States)

    Wang, Ping; Meng, Qing-min; Long, Hong-ming; Li, Jia-xin

    2016-08-01

    The viscosity of experimental slag, which was mixed based on the composition of a practical blast furnace slag, was measured in this paper. The influence of Al2O3 and MgO content, basicity R2 = w(CaO)/w(SiO2) on the fluidity of slag was studied. The stepwise regression analysis in SPSS was used to reveal the relationship between sulfur distribution coefficient LS and slag composition as well as furnace temperature. The results show that increasing of MgO up to 12% can decrease the slag viscosity. The w(MgO) should be controlled below 8% when there is 20% Al2O3 in the slag. Temperature of hot metal and content of CaO in slag are the two dominant factors on the desulfurization capacity of slag.

  11. Effect of MgO and MnO on Phosphorus Utilization in P-Bearing Steelmaking Slag

    Science.gov (United States)

    Lin, Lu; Bao, Yan-Ping; Wang, Min; Li, Xiang

    2016-04-01

    In order to recycle the phosphorus in P-bearing converter slag and make it used as slag phosphate fertilizer, the effect of MgO and MnO in P-bearing steelmaking slag on phosphorus existence form, P2O5 solubility and magnetic separation behavior were researched systematically. The results show that the phosphorus in slag is mainly in the form of n2CaO · SiO2-3CaO · P2O5 (for short nC2S-C3P) solid solution in the P-rich phase for CaO-SiO2-FetO-P2O5-X (X stands for MgO and MnO, respectively). And the increasing of MgO and MnO content has no influence on precipitation of nC2S-C3P solid solution in slag, MnO and MgO mainly enter into RO phase and base phase to form MnFe2O4 and MgFe2O4, which has little effect on the P2O5 content of P-rich phase, so which has little effect on the degree of phosphorus enrichment and phosphorus occurrence form of the P-bearing slag. And adding MgO and MnO into CaO-SiO2-P2O5-Fe2O3 slag system can break the complex net structure formed by Si-O on certain degree, and also hinder the precipitation of β-Ca3(PO4)2 crystal with low citric acid solubility during the melting-cooling process. Therefore, adding appropriate MgO and MnO content into slag can improve the slag P2O5 solubility, but the effect of different amounts of MgO and MnO on the P2O5 solubility has little difference. Meanwhile, adding MgO and MnO into slag can improve the metallization of slag and magnetism of iron-rich phase, make the magnetic substances content increase and separation of phosphorus and iron incomplete, so it is adverse to phosphorus resources recovery from P-bearing slag by magnetic separation method. In order to recycle the phosphorus in P-bearing converter slag, the MgO and MnO content in the P-bearing slag should be controlled in the steelmaking process.

  12. Effect of FeO and CaO on the Sulfide Capacity of the Ferronickel Smelting Slag

    Science.gov (United States)

    Kim, Ki Deok; Huh, Wan Wook; Min, Dong Joon

    2014-06-01

    The effect of FeO and CaO on the sulfide capacity in MgO-SiO2-FeO based slags equilibrating with Fe-Ni alloys at 1773 K and 1873 K (1500 °C and 1600 °C) was investigated. The sulfide capacity in the MgO-SiO2-FeO and MgO-SiO2-CaO-FeO slags increased with higher FeO content and higher temperatures due to an increase in the activity of O2- and a decrease in the activity coefficient of sulfide ion in slag. The sulfide capacity of the MgO-SiO2-CaO-FeO slag also increased with an increase in the CaO content due largely to the increase in the activity of O2-. Furthermore, CaO and FeO seem to be more effective than MgO in increasing the sulfide capacity in the MgO-SiO2-CaO-FeO slag system. In addition, the comparison of the experimental results with the theoretical estimate using the modified empirical optical basicity showed relatively good linear agreement.

  13. CAOS/COMPLEJIDAD, FRACTALES E IDENTIDADES SOCIALES

    OpenAIRE

    Gustavo Alvarez Vázquez

    2012-01-01

    En el presente artículo se presenta una propuesta para articular elementos básicos de la Teoría del Caos/Complejidad y la geometría fractal con el estudio de las identidades sociales, partiendo de la tesis que dicha teoría presenta una revolución paradigmática desde cuestiones epistemológicas, la cual es consecuencia no de la transformación de la realidad, sino de la modificación del esquema de percepción que de ella se ha dado en las ciencias en el último siglo, cuestión que también es posib...

  14. CAOS spectroscopy of Am stars Kepler targets

    CERN Document Server

    Catanzaro, G; Biazzo, K; Busa', I; Frasca, A; Leone, F; Giarrusso, M; Munari, M; Scuderi, S

    2015-01-01

    The {\\it Kepler} space mission and its {\\it K2} extension provide photometric time series data with unprecedented accuracy. These data challenge our current understanding of the metallic-lined A stars (Am stars) for what concerns the onset of pulsations in their atmospheres. It turns out that the predictions of current diffusion models do not agree with observations. To understand this discrepancy, it is of crucial importance to obtain ground-based spectroscopic observations of Am stars in the {\\it Kepler} and {\\it K2} fields in order to determine the best estimates of the stellar parameters. In this paper, we present a detailed analysis of high-resolution spectroscopic data for seven stars previously classified as Am stars. We determine the effective temperatures, surface gravities, projected rotational velocities, microturbulent velocities and chemical abundances of these stars using spectral synthesis. These spectra were obtained with {\\it CAOS}, a new instrument recently installed at the observing station...

  15. 氧化钾/SBA-15催化合成碳酸二正丁酯%SYNTHESIS OF DIBUTYL CARBONATE BY TRANSESTERIFICATION OVER MESOPOROUS MOLECULAR SIEVE K2O/SBA-15

    Institute of Scientific and Technical Information of China (English)

    崔晓燕; 沈健

    2011-01-01

    以介孔分子筛SBA-15为载体,浸渍KNO3后经过焙烧,制得K2O/SBA-15固体碱催化剂.通过XRD,N2等温吸附脱附和IR等测试手段对试样进行了分析.研究了K2O/SBA-15催化碳酸二甲酯(DMC)与正丁醇(n-BuOH)酯交换合成碳酸二正丁酯(DBC)的反应.结果表明:当K2O负载量为2%,反应时间2 h,反应温度180℃,n(正丁醇)∶n(DMC)为3.0,m(催化剂)∶m(原料)为0.08时,DMC转化率最大为89.6%,DBC 收率为58%,DBC选择性为64.7%.并且K2O/SBA-15催化剂重复使用多次仍具有较好的催化效果.%K2O/SBA-15 as the solid base catalyst was synthesized bu loading potassium on mesoporous sieve SBA-15.The sample has been characterized by XRD, N2 adsorption desorption and IR.The study on the synthesis of dibutyl carbonate from dimethyl carbonate and butanol has been done.The experimental results showed that when the loaded mount of K2 O was 2 %, reaction time was 2 h, reaction temperature was 180 ℃ ,n(n-butanol): n(dimethyl carbonate) was 3 and the ratio of catalyst to raw material was 8%, the highest conversion of dimethyl carbonate was 89.6%, the yield of DBC was 58%, the selectivity to DBC was 64.7%.The results also showed that the K2O/SBA-15 could be reused with good catalytic effect.

  16. Behavior of CaO and Calcium in pure Magnesium

    Institute of Scientific and Technical Information of China (English)

    HA Seong-Ho; LEE Jin-Kyu; JO Hyung-Ho; JUNG Seung-Boo; KIM Shae K.

    2006-01-01

    Mg alloys exhibit a number of good properties such as low density, good castability and high specific strength.However, molten Mg and Mg alloys are ignited without the melt protective gases during melting and casting process due to their high reactivity.The purpose of this study is to investigate effects of Ca and CaO on pure Mg through microstructure observation, ignition test and phase analysis.With increasing Ca and CaO contents, the ignition resistance of Ca or CaO added pure Mg is increased and the grains are refined.As results of XRD and EDS, CaO is reduced to Ca in CaO added pure Mg.Mg2Ca phase is formed even in 0.1 wt.%CaO added pure Mg by reduction mechanism, while Mg2Ca phase is formed over 1.35 wt.% Ca added pure Mg.

  17. Antibacterial characteristics of CaCO{sub 3}-MgO composites

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Osamu, E-mail: yamamoto@cges.akita-u.ac.jp [Center for Geo-Environmental Science, Faculty of Engineering and Resource Science, Akita University, 1-1 Tegata Gakuen-machi, Akita 010-8502 (Japan); Ohira, Toshiaki; Alvarez, Kelly [Center for Geo-Environmental Science, Faculty of Engineering and Resource Science, Akita University, 1-1 Tegata Gakuen-machi, Akita 010-8502 (Japan); Fukuda, Masayuki [Division of Dentistry and Oral Surgery, Akita University Hospital, 1-1-1 Hondo, Akita 010-8543 (Japan)

    2010-10-15

    Dentifrices, such as tooth-paste, are pastes containing insoluble abrasives that aid in the removal of plaque from the teeth and help to polish them. Composite powders contributing to oral hygiene application, i.e., nano-scale MgO crystallite dispersed in CaCO{sub 3} grain, were fabricated by the thermal decomposition of dolomite. The composite obtained by heating at 800 deg. C consisted of CaCO{sub 3} grains including 20 nm MgO fine crystallite, being the purpose powder in this study. The antibacterial activity of these powders related to gram-positive and gram-negative bacteria was evaluated in vitro. The thermal decomposition above 800 deg. C resulted in the mixture of CaO and MgO. Antibacterial activity of the composite enhanced with increasing powder concentration. Though antibacterial action toward Staphylococcus aureus was greater than towards Escherichia coli, the death rate constant was identical in both bacteria. It can be concluded that the obtained composite possesses two functions able to improve the oral hygiene: as a tooth abrasive and as an antibacterial agent.

  18. In memory of Professor Tianqin Cao(Tien-chin Tsao)

    Institute of Scientific and Technical Information of China (English)

    Youshang Zhang

    2010-01-01

    @@ In December this year,the 4th Tianqin Cao Memorial Symposium on Protein Research will be held in Xiamen(Amoy).On this occasion,it is my pleasure to write a recollection in memory of Professor Tianqin Cao.It was rather late when Ⅰ was able to study in Prof.Cao's laboratory as a graduate student in the Institute of Biochemistry.After graduating from the Department of Chemical Engineering of Zhejiang University in 1948,Ⅰ could not find a job in a chemical engineering factory; therefore,Ⅰ changed my profession to biochemistry and worked as an assistant in the Department of Biochemistry of Hunan Yale Medical College.

  19. Synthesis of Dimethyl Carbonate from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2-MgO.

    Science.gov (United States)

    Jun, Jin Oh; Lee, Joongwon; Kang, Ki Hyuk; Song, In Kyu

    2015-10-01

    A series of CeO2(X)-MgO(1-X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared by a co-precipitation method for use in the synthesis of dimethyl carbonate from ethylene carbonate and methanol. Among the CeO2(X)-MgO(1-X) catalysts, CeO2(0.25)-MgO(0.75) nano-catalyst showed the best catalytic performance. Alkali and alkaline earth metal oxides (MO = Li2O, K2O, Cs2O, SrO, and BaO) were then supported on CeO2(0.25)-MgO(0.75) by an incipient wetness impregnation method with an aim of improving the catalytic performance of CeO2(0.25)-MgO(0.75). Basicity of the catalysts was determined by CO2-TPD experiments in order to elucidate the effect of basicity on the catalytic performance. The correlation between catalytic performance and basicity showed that basicity played an important role in the reaction. Yield for dimethyl carbonate increased with increasing basicity of the catalysts. Among the catalysts tested, Li2O/CeO2(0.25)-MgO(0.75) nano-catalyst with the largest basicity showed the best catalytic performance in the synthesis of dimethyl carbonate.

  20. A Psychobiographical Study of Cao Cao's Personality%曹操人格的心理传记学分析

    Institute of Scientific and Technical Information of China (English)

    谢章明; 解登峰; 刘征宇

    2014-01-01

    通过心理传记学研究探讨曹操的主要人格特点。采用人格形容词评定法和心理传记分析法,结果表明曹操具有“机智勇敢”、“乐观开朗”、“赏罚分明”、“目光远大”、“奸诈狡猾”、“残忍狠毒”六大人格特征。通过对该评定结果与收集到的历史资料进行相互印证,分析曹操人格特征形成的影响因素。%The research explores Cao Cao's personality character-istics and its formation process through psychobiographical study. The result shows that Cao Cao's personality structures consisted of the following factors: "tactful and brave", "optimistic and cheerful","harsh reward and punishment","foresight","treacher-ous and cunning" and "cruel and vicious" six major personality traits. Cao Cao's personality characteristics resulted from the in-teraction of inherited trait and social environment.

  1. APLICABILIDADE DA TEORIA DO CAOS A ORGANIZAÇÕES

    Directory of Open Access Journals (Sweden)

    Ernesto José Vieira

    2015-01-01

    Full Text Available Objetivou-se compreender os fundamentos da Teoria do Caos na gestão das empresas e a existência de elementos típicos dessa teoria nos processos de planejamento, e variáveis controláveis que previnam o caos de ruptura. Além disso, foi também investigado se visão, missão e objetivos corporativos consistem em atratores que evitem a instalação do caos de ruptura; e variáveis e faixas de controle utilizadas pelos dirigentes para evitar o caos de ruptura. A metodologia qualitativa empregou estudo exploratório, para identificar as variáveis e faixas de controle empregadas. Estudaram-se dez empresas da Grande Belo Horizonte. Os resultados validaram as proposições teóricas iniciais, indicando a possibilidade da utilização dos conceitos da Teoria do Caos em mercados altamente competitivos.

  2. Pressureless sintering of translucent MgO ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dianying [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Jordan, Eric H. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States)], E-mail: jordan@engr.uconn.edu; Gell, Maurice [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)

    2008-10-15

    MgO nanocrystalline powders were synthesized via a wet precipitation process. X-ray diffraction analysis of the heat-treated precursor powders shows that a crystalline MgO phase forms at {approx}500 deg. C. Translucent MgO ceramics were prepared by pressureless sintering the nanocrystalline MgO powders at 1400 deg. C for 2 h under ambient atmosphere. The as-sintered MgO ceramics have a relative density of 98.1% with an average hardness of 6.8 GPa. Scanning electron microscope characterization revealed that the translucent MgO ceramics have an average grain size of {approx}6 {mu}m.

  3. Coded access optical sensor (CAOS) imager and applications

    Science.gov (United States)

    Riza, Nabeel A.

    2016-04-01

    Starting in 2001, we proposed and extensively demonstrated (using a DMD: Digital Micromirror Device) an agile pixel Spatial Light Modulator (SLM)-based optical imager based on single pixel photo-detection (also called a single pixel camera) that is suited for operations with both coherent and incoherent light across broad spectral bands. This imager design operates with the agile pixels programmed in a limited SNR operations starring time-multiplexed mode where acquisition of image irradiance (i.e., intensity) data is done one agile pixel at a time across the SLM plane where the incident image radiation is present. Motivated by modern day advances in RF wireless, optical wired communications and electronic signal processing technologies and using our prior-art SLM-based optical imager design, described using a surprisingly simple approach is a new imager design called Coded Access Optical Sensor (CAOS) that has the ability to alleviate some of the key prior imager fundamental limitations. The agile pixel in the CAOS imager can operate in different time-frequency coding modes like Frequency Division Multiple Access (FDMA), Code-Division Multiple Access (CDMA), and Time Division Multiple Access (TDMA). Data from a first CAOS camera demonstration is described along with novel designs of CAOS-based optical instruments for various applications.

  4. Thermoelasticity of CaO from first principles

    Institute of Scientific and Technical Information of China (English)

    Liu Zi-Jiang; Qi Jian-Hong; Guo Yuan; Chen Qi-Feng; Cai Ling-Cang; Yang Xiang-Dong

    2007-01-01

    The thermoelastic properties of CaO over a wide range of pressure and temperature are studied using density functional theory in the generalized gradient approximation. The transition pressure taken from the enthalpy calculations is 66.7 GPa for CaO, which accords with the experimental result very well. The athermal elastic moduli of the two phases of CaO are calculated as a function of pressure up to 200 GPa. The calculated results are in excellent agreement with existing experimental data at ambient pressure and compared favourably with other pseudopotential predictions over the pressure regime studied. It is also found that the degree of the anisotropy rapidly decreases with pressure increasing in the B1 phase, whereas it strongly increases as the pressure increases in the B2 phase. The thermodynamic properties of the B1 phase of CaO are predicted using the quasi-harmonic Debye model; the heat capacity and entropy are consistent with other previous results at zero pressure.

  5. Infrared-to-green upconversion properties of Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses upon excitation with 976 nm lasers diode

    Institute of Scientific and Technical Information of China (English)

    SU Fang-ning; DENG Zai-de

    2006-01-01

    The energy transfer and upconversion of Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses upon excitation with 976 nm lasers diode were studied. The tellurite glasses were prepared by conventional melting methods. Their optical properties and sensitization upconversion spectra were performed. The dependence of green upconversion luminescence intensity on the mole ratio of Yb3+ to Er3+ and Er3+ concentration were discussed in detail. When the mole ratio of Yb3+ to Er3+ is 25/1 and Er3+ concentration is 0.1% (mole fraction), or when the mole ratio of Yb3+ to Er3+ is 10/1 and Er3+ concentration is 0.15%, the optimal upconversion luminescence intensity is obtained. The obtained glasses can be one of the potential candidates for lasers-diode pumping microchip solid-state lasers.

  6. Thermal Stability and Infrared-To Upconversion Emissions of Er3+/Yb3+ Co-Doped 70GeO2-20PbO-10K2O Glasses

    Science.gov (United States)

    Ahmed, Samah M.; Shaltout, I.; Badr, Y.

    2011-06-01

    Er3+/Yb3+ co-doped potassium-lead-germanate (70GeO2-20PbO-10K2O) glasses with a fixed concentration of Er3+ ions (0.5 mol. %) and different concentrations of Yb3+ ions (0, 0.5, 1.5, and 2.5 mol. %), have been synthesized by the conventional melting and quenching method. The structure and vibrational modes of the glass network were investigated by the infrared absorption and Raman spectroscopy. The thermal behavior of all glass samples was investigated by the differential thermal analysis. Infrared-to-visible frequency upconversion process was investigated in all glasses. Intense green and red upconversion emission bands centered at around 532, 546, and 655 nm were observed, underallglasses.Intense excitation at 980 nm of diode laser at room temperature. The dependence of these emissions on the excitation power was investigated.

  7. Influence of alkali mixed effect on the mixing enthalpy in 0.7582O3-0.25[xNa2O-(1-x)K2O]glass system

    Institute of Scientific and Technical Information of China (English)

    A.Kouyate; A.E Ahoussou; A.Yapi; D.Diabate; J.Rogez; A.Trokourey

    2008-01-01

    The mixed alkali effect was investigated in the glass system 0.7582O3-0.25[xNa2O-(1-x)K2O]through thermodynamic properties.The calorimetric measurements were performed in HF solution calorimetry at 298 K,The mixing enthalpy values show non-linear behaviour upon substitution of one alkali ion by another.This thermodynamic non-idealiIy is caused by the slight variations of distance between metallic cations,the macromolecular structure being unchanged.It can be explained,at least qualitatively,using electrolyte theory based on the Coulombic interactions of charged species originally developed by Debye and Hiickel.

  8. Formation and Stability of Hollow MgO Nanoshells

    NARCIS (Netherlands)

    Krishnan, G.; Palasantzas, G.; Kooi, B.J.

    2010-01-01

    High temperature annealing of gas phase synthesized Mg nanoparticles surrounded by an MgO shell leads to formation of hollow MgO nanoshells due to the evaporation assisted Kirkendall effect. Under electron beam exposure in TEM, the (220) MgO facets reduce their high surface energy by forming cube fa

  9. 20世纪曹操形象诠释综述%A Review of Image Interpretations of Cao Cao in the 20th Century

    Institute of Scientific and Technical Information of China (English)

    郭素媛

    2012-01-01

      With historical changes of the 20th century, interpreters, starting from their respective historical stances, have made distinc-tive interpretations about the image of Cao Cao. Therefore, the image of Cao Cao develops with those rich and colorful interpretations. The interpretative history of the image of Cao Cao in the 20th century is also a historical reality.%  20世纪,随着历史的风云变幻,诠释者从各自的历史性出发对曹操形象做出了带有鲜明时代印记的诠释.曹操形象也在这些丰富多彩的诠释中得到了丰富、发展.20世纪曹操形象的诠释史就是它的存在史.

  10. Full-potential KKR-calculations for MgO and divalent impurities in MgO

    OpenAIRE

    Baranov, A. N.; Stepanyuk, V. S.; Hergert, W.; Katsnelson, A. A.; Settels, A.; Zeller, R.; Dederichs, P. H.

    2002-01-01

    We present a detailed investigation of bulk properties of MgO and lattice relaxations around divalent impurities in MgO by means of the full-potential Korringa-Kohn-Rostoker Green's function method. The local-density approximation and the perturbative generalized gradient corrections are used to calculate the lattice constant and bulk modulus of MgO. We obtain a very good description of the ground properties of MgO. Lattice relaxations around divalent impurities in MgO are determined using an...

  11. K2O对合成 DMC用 Cu-Ni/V2O5-SiO2催化剂性能的影响%Effect of K2O on Properties of Cu-Ni/V2O5-SiO2 Catalyst for the Synthesis of Dimethyl Carbonate

    Institute of Scientific and Technical Information of China (English)

    黎汉生; 钟顺和; 王建伟; 肖秀芬

    2001-01-01

    V2O5-SiO2(VSiO) supported Cu-Ni-K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro-reactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on Cu-Ni/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15 % , K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on Cu-Ni-K2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by-products decreases.

  12. Introduction à la CAO CADENCE - French version only

    CERN Multimedia

    Davide Vitè

    2002-01-01

    CERN Technical Training Programme: Learning for the LHC ! Dans le cadre du suivi du programme ELEC-2002 : Electronics in HEP, une nouvelle session du cours Introduction à la CAO CADENCE : de la saisie de schéma Concept-HDL au PCB est programmée pour les 10 et 11 décembre prochains. Le cours, en français, est gratuit et sera animé par Serge Brobecker de la division IT/PS/EAS. L'objectif de cette formation est de donner une vue générale du système CAO CADENCE utilisé au CERN, et d'en connaître l'environnement et les possibilités, en acquérant des notions suffisantes pour utiliser la saisie de schéma. Le cours est ciblé pour une audience d'ingénieurs et techniciens désirant utiliser les outils CAO disponibles au CERN, afin de concevoir des circuits logiques et des circuits programmables digitaux. Si vous désirez partic...

  13. Crystallization of MgFe2O4 from a glass in the system K2O/B2O3/MgO/P2O5/Fe2O3

    Science.gov (United States)

    El Shabrawy, Samha; Bocker, Christian; Rüssel, Christian

    2016-10-01

    Spherical magnetic Mg-Fe-O nanoparticles were successfully prepared by the crystallization of glass in the system K2O/B2O3/MgO/P2O5/Fe2O3. The magnetic glass ceramics were prepared by melting the raw materials using the conventional melt quenching technique followed by a thermal treatment at temperatures in the range 560-700 °C for a time ranging from 2 to 8 h. The studies of the X-ray diffraction, electron microscopy and FTIR spectra confirmed the precipitation of finely dispersed spherical (Mg, Fe) based spinel nanoparticles with a minor quantity of hematite (α-Fe2O3) in the glass matrix. The average size of the magnetic nano crystals increases slightly with temperature and time from 9 to 15 nm as determined by the line broadening from the XRD patterns. XRD studies show that annealing the glass samples for long periods of time at temperature ≥604 °C results in an increase of the precipitated hematite concentration, dissolution of the spinel phase and the formation of magnesium di-borate phase (Mg2B2O5). For electron microscopy, the particles were extracted by two methods; (i) replica extraction technique and (ii) dissolution of the glass matrix by diluted acetic acid. An agglomeration of the nano crystals to larger particles (25-35 nm) was observed.

  14. MgO nanoparticles as antibacterial agent: preparation and activity

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhen-Xing, E-mail: tangzhenxing@126.com [Department of Food Science, Anqing, Vocational and Technical College, Anqing, Anhui (China); Lv, Bin-Feng [Date Palm Research Center, King Faisal University, (Saudi Arabia)

    2014-07-15

    Bacterial pollution is a great risk for human health. Nanotechnology offers a way to develop new inorganic antibacterial agents. Nano-inorganic metal oxide has a potential to reduce bacterial contamination. MgO is an important inorganic oxide and has been widely used in many fields. Many studies have shown that MgO nanoparticles have good antibacterial activity. Therefore, in this paper, the main synthesis methods, antibacterial activity and antibacterial mechanisms of MgO nanoparticles are reviewed. (author)

  15. MgO nanoparticles as antibacterial agent: preparation and activity

    OpenAIRE

    Zhen-Xing Tang; Bin-Feng Lv

    2014-01-01

    Bacterial pollution is a great risk for human health. Nanotechnology offers a way to develop new inorganic antibacterial agents. Nano-inorganic metal oxide has a potential to reduce bacterial contamination. MgO is an important inorganic oxide and has been widely used in many fields. Many studies have shown that MgO nanoparticles have good antibacterial activity. Therefore, in this paper, the main synthesis methods, antibacterial activity and antibacterial mechanisms of MgO nanoparticles are r...

  16. The Oxygenase CAO-1 of Neurospora crassa Is a Resveratrol Cleavage Enzyme

    KAUST Repository

    Diaz-Sanchez, V.

    2013-07-26

    The genome of the ascomycete Neurospora crassa encodes CAO-1 and CAO-2, two members of the carotenoid cleavage oxygenase family that target double bonds in different substrates. Previous studies demonstrated the role of CAO-2 in cleaving the C40 carotene torulene, a key step in the synthesis of the C35 apocarotenoid pigment neurosporaxanthin. In this work, we investigated the activity of CAO-1, assuming that it may provide retinal, the chromophore of the NOP-1 rhodopsin, by cleaving β-carotene. For this purpose, we tested CAO-1 activity with carotenoid substrates that were, however, not converted. In contrast and consistent with its sequence similarity to family members that act on stilbenes, CAO-1 cleaved the interphenyl Cα-Cβ double bond of resveratrol and its derivative piceatannol. CAO-1 did not convert five other similar stilbenes, indicating a requirement for a minimal number of unmodified hydroxyl groups in the stilbene background. Confirming its biological function in converting stilbenes, adding resveratrol led to a pronounced increase in cao-1 mRNA levels, while light, a key regulator of carotenoid metabolism, did not alter them. Targeted Δcao-1 mutants were not impaired by the presence of resveratrol, a phytoalexin active against different fungi, which did not significantly affect the growth and development of wild-type Neurospora. However, under partial sorbose toxicity, the Δcao-1 colonies exhibited faster radial growth than control strains in the presence of resveratrol, suggesting a moderate toxic effect of resveratrol cleavage products.

  17. Caos en sistemas clásico-cuánticos

    Science.gov (United States)

    Dirani, L. D.; Núñez, J. A.

    Una de las formas de estudiar la existencia de caos en el comportamiento de un sistema clásico-cuántico, es truncando el espacio de Hilbert del sistema cuántico. El objetivo de este trabajo es analizar como afecta dicho truncamiento en la dinámica del sistema. Para tal fin se propone un Hamiltoniano integrable, cuyos valores de expectación asociados a coordenadas y momentos cuánticos responden, por el teorema de Ehrenfest, a un sistema de dos osciladores clásicos con acoplamiento lineal.

  18. Conference “Computational Analysis and Optimization” (CAO 2011)

    CERN Document Server

    Tiihonen, Timo; Tuovinen, Tero; Numerical Methods for Differential Equations, Optimization, and Technological Problems : Dedicated to Professor P. Neittaanmäki on His 60th Birthday

    2013-01-01

    This book contains the results in numerical analysis and optimization presented at the ECCOMAS thematic conference “Computational Analysis and Optimization” (CAO 2011) held in Jyväskylä, Finland, June 9–11, 2011. Both the conference and this volume are dedicated to Professor Pekka Neittaanmäki on the occasion of his sixtieth birthday. It consists of five parts that are closely related to his scientific activities and interests: Numerical Methods for Nonlinear Problems; Reliable Methods for Computer Simulation; Analysis of Noised and Uncertain Data; Optimization Methods; Mathematical Models Generated by Modern Technological Problems. The book also includes a short biography of Professor Neittaanmäki.

  19. Effect of CaO composition on oxidation and burning behaviors of AM50 Mg alloy

    Institute of Scientific and Technical Information of China (English)

    Jin-Kyu LEE; Shae K. KIM

    2011-01-01

    Oxidation and burning behaviors were studied for CaO added AM50 Mg composites which were manufactured by conventional melting and casting processes without SF6 protective gas. CaO added AM50 Mg composites show the stable oxidation resistance. while AM50 Mg alloys show the poor oxidation resistance. The effects of CaO addition on the burning resistance under ambient, nitrogen and dry air atmospheres were examined for CaO added AM50 Mg composites. With increasing CaO addition, the burning temperature increases under ambient, nitrogen and dry air atmospheres. The burning temperatures of small test specimen under all conditions greatly increase even by 0.3% CaO (mass fraction) addition into AM50 Mg alloys.

  20. Interstitial Fe in MgO

    CERN Document Server

    Mølholt, T E; Gunnlaugsson, H P; Svane, A; Masenda, H; Naidoo, D; Bharuth-Ram, K; Fanciulli, M; Gislason, H P; Johnston, K; Langouche, G; Ólafsson, S; Sielemann, R; Weyer, G

    2014-01-01

    Isolated Fe-57 atoms were studied in MgO single-crystals by emission Mossbauer spectroscopy following implantation of Mn-57 decaying to Fe-57. Four Mossbauer spectral components were found corresponding to different Fe lattice positions and/or charge states. Two components represent Fe atoms substituting Mg as Fe2+ and Fe3+, respectively; a third component is due to Fe in a strongly implantation-induced disturbed region. The fourth component, which is the focus of this paper, can be assigned to Fe at an interstitial site. Comparison of its measured isomer shift with ab initio calculations suggests that the interstitial Fe is located on, or close to, the face of the rock-salt MgO structure. To harmonize such an assignment with the measured near-zero quadrupole interaction a local motion process (cage motion) of the Fe has to be stipulated. The relation of such a local motion as a starting point for long range diffusion is discussed.

  1. Development of electrically insulating CaO coatings

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Reed, C.B.; Uz, M.; Rink, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    A systematic study has been initiated to develop electrically insulating CaO coatings by vapor phase transport and by in-situ formation in a liquid Li environment. Several experiments were conducted in vapor transport studies with variations in process temperature, time, specimen location, specimen surface preparation, and pretreatment. Several of the coatings obtained by the method exhibited Ca concentration in the range of 60--95 wt.% on the surface. However, coating thickness has not been very uniform among several samples exposed in the same run or even within the same sample. The coatings developed in these early tests degraded after 24 h exposure to Li at 500 C. Additional experiments are underway to develop better-adhering and more dense coatings by this method. A program to develop in-situ CaO coatings in Li has been initiated, and the first set of capsule tests at 800 C in three different Li-Ca mixtures will be completed in early July. Specimens included in the run are bare V-4Cr-4Ti alloy, specimens with a grit-blasted surface and O-precharged in 99.999% Ar, polished specimens precharged in a 99.999% Ar and 5000 ppm O{sub 2}-N{sub 2} mixture, and prealuminized V-5Cr-5Ti alloy preoxidized in a 5000 ppm O{sub 2}-N{sub 2} mixture. Additional experiments at lower temperatures are planned.

  2. Bartleby o la política del caos

    Directory of Open Access Journals (Sweden)

    Andrés Camilo Torres Estrada

    2013-01-01

    Full Text Available El artículo presenta un análisis del cuento de Herman Melville: “Bartleby, el escribiente”. Este análisis parte de un acercamiento a la literatura desde una noción de política inspirada en autores como Jacques Derrida y Jacques Rancière, pero que se aparta de esta filosofía cuando, por encima del propio texto y sus posibilidades, se pretende encontrar en él heterotopías, esperanzas y comunidades por venir. Esta noción de política acerca a la literatura al mundo efectivo, transfigurando los modos de ser y no ser. Así, el personaje de Bartleby se presenta en medio del mundo de la representación como un agente del caos. En esto consiste la política del escribiente: su incursión devela las farsas del mundo construido y soñado por los hombres; pero esta destrucción que causa es inútil: el mundo de la representación ha sentido su absurdo, no sabe qué hacer con dicho agente del caos, pero no es suficiente para arruinarlo. Bartleby, quien se ha indeterminado y ha abandonado las dualidades de ser y no ser, tampoco puede seguir viviendo: ya no hay espacio para la vida sin referencias en un mundo humano y ficticio.

  3. Effect of CaO on Fluorine in the Decomposition of REFCO3

    Institute of Scientific and Technical Information of China (English)

    Sun Shuchen; Wu Zhiying; Gao Bo; Bian Xue; Wu Wenyuan; Tu Ganfeng

    2007-01-01

    Influence of CaO on thermal decomposition of REFCO3 was studied. The results showed that CaO did not affect significantly the decomposition ratio of REFCO3. The XRD experiment showed that there was a great deal of CaF2 in the roasting production, the gas chromatographic analysis on the gas of REFCO3 decomposed, and the 70% content of fluorine in the gas of REFCO3 added 15% CaO was reduced. CaO could absorb the fluorine from the decomposition of REFCO3, and the environmental pollution of the fluorine was greatly alleviated.

  4. Fabrication and spectroscopic properties of transparent Nd3+:MgO and Er3+:MgO ceramics

    Science.gov (United States)

    Sanamyan, T.; Cooper, C.; Gilde, G.; Sutorik, A. C.; Dubinskii, M.

    2014-06-01

    We present the results of the development and comprehensive characterization of fully densified Er3+:MgO and Nd3+:MgO transparent ceramics fabricated from specially formulated nanopowders. Also presented are the spectroscopic characterization results (absorption, fluorescence and emission lifetimes) of Er3+ and Nd3+ dopant ions in MgO in the temperature range 10 to 300 K. To the best of our knowledge, this is the first reported successful demonstration of bulk MgO host material doped with rare earth (RE) ions. Spectroscopic results are indicative of a single-site RE ion incorporation with a nearly perfect single crystalline environment within the MgO ceramic grains. The results are presented with major emphasis on potential laser application and the outlook for substantially improved laser power scaling at room temperature based on the unique thermal properties of the host material.

  5. Effects of Sm 3+/Yb 3+ co-doping and temperature on the Raman, IR spectra and structure of [TeO 2-GeO 2-K 2O-Sm 2O 3/Yb 2O 3] glasses

    Science.gov (United States)

    Shaltout, I.; Badr, Y.

    2006-05-01

    Effects of Sm 3+/Yb 3+ co-doping on Raman scattering, IR absorption, temperature dependence of the Raman spectra up to 210 °C and the structure of two glass systems of the composition (80TeO 2-10GeO 2-8K 2O-2Sm 2O 3/Yb 2O 3) is discussed. It was found that the addition of Yb 3+ to the glass very strongly enhances the intensities of the antistokes’ Raman bands at 155, 375, 557 and 828 cm -1 and quenches both the intensities of the stokes’ vibration modes of the TeO 4 units in the range of 120-770 cm -1 and the intensities of the OH - stretching vibration modes in the range of 2600-3300 cm -1. Sm 2O 3/Yb 2O 3 rare earth co-doping has a great influence on removing and/or changing the nature of the OH - groups. The appearance and splitting of the stretching vibration modes of the OH - groups at lower frequencies (2770, 2970 cm -1) for the Sm +3 singly doped glass sample, compared to the band at ∼3200 cm -1 for the Sm 3+/Yb 3+ co-doped glass sample, suggested that the OH - groups are more strongly bonded and incorporated with the glass matrix for the singly doped glass. Heating the sample up continuously weakens the hydrogen bonding of the OH - groups to the glass matrix leading to creation of NBO and breakdown of the connectivity of the OH - groups to the TeO 4, TeO 3+1 and TeO 3 structural units. Raman bands at 286, 477, 666 and 769 cm -1 were assigned to its respective vibrations of Te 2O 7, TeO 4-4 species, the (Te-O-Te) bending vibrations of the TeO 4 triagonal bipyramids (tbps), the axial symmetric stretching vibration modes (Te ax-O) s with bridging oxygen BO atoms and to the (Te-O) nbo non-bridging stretching vibration modes of the TeO 3+1 and/or TeO 3 pyramids.

  6. APLICABILIDADE DA TEORIA DO CAOS A ORGANIZAÇÕES

    Directory of Open Access Journals (Sweden)

    VIEIRA, Ernesto Jose

    2014-10-01

    Full Text Available This study seeks to verify if there are typical elements in Chaos Theory in organizations as well as to verify if vision, mission, and objectives consist of attractors which prevent the installation of bifurcation or chaos rupture. In order to respond to these questions, it was necessary to include in this study general in addition to specific objectives. As a support a theoretical reference on Chaos Theory was developed. This theory presents a system with order within an apparently random system with patterns - behaviors which occur more than once, through time. The qualitative methodology utilized exploratory study. Ten companies within Metropolitan Belo Horizonte were studied. The results validated the initial theoretical propositions. En este trabajo se trata de determinar si existen elementos típicos de la teoría del caos en las organizaciones, así como la visión, misión y objetivos consisten en atractores que impiden bifurcación o punto de ruptura instalar. Para responder a estas preguntas, se hizo necesario incluir en este estudio un objetivo general más allá específico.Como apoyo desarrollado un marco teórico sobre la Teoría del Caos.Esta teoría se presenta un sistema con un orden aparentemente aleatoria con las normas - comportamentos que ocurre más de una vez en el tiempo. Entonces-se dirigió a la metodología que se clasifica como cualitativa, a través de un estudio exploratorio para evaluar diez empresas de Gran Belo Horizonte. Se analizaron los datos obtenidos de entrevistas cuando se llegó a la conclusión de que los resultados observados validan las declaraciones iniciales. Este trabalho procura verificar se existem elementos típicos da Teoria do Caos em organizações, assim como se a visão, missão e objetivos consistem em atratores que evitam que a bifurcação ou ponto de ruptura se instale. Para responder à estas perguntas, tornou-se necessário incluir nesta pesquisa um objetivo geral além dos espec

  7. Optical Properties and Electronic Structure of CaO

    Science.gov (United States)

    Sobolev, V. V.; Merzlyakov, D. A.; Sobolev, V. Val.

    2016-09-01

    Spectra of 11 optical functions of CaO in the ranges 6.5-7.2 eV at 2 K and 0-60 eV at 77 K were determined. A total of 14 maxima and shoulders of excitons and interband transitions were found including two distinct exciton structures at 6.9 and 11.4 eV and volume and surface plasmon maxima at ~38.3 and 33.2 eV, respectively. Their principal features and general trends were established. Variable formation efficiencies of spectra of the dielectric permittivity and characteristic electron-energy losses in different spectral ranges were analyzed. The calculations used known experimental reflectance spectra and computer programs based on the Kramers-Kronig correlations and analytical formulae for the relationship between optical functions.

  8. Antioxidant status in MgO nanoparticle-exposed rats.

    Science.gov (United States)

    Kiranmai, G; Reddy, A Rama Narsimha

    2013-11-01

    In this present study, antioxidant status was evaluated in rat serum following exposure to magnesium oxide (MgO) nanoparticles. The lungs of rats were intratracheally instilled with (single dose) phosphate-buffered saline (PBS) + 1% of Tween 80 (solvent control) or MgO or carbonyl iron (negative control) or quartz particles (positive control) at a dose of 1 and 5 mg/kg of body weight. The blood samples were collected at 1, 7, and 30 days of postinstillation of nanoparticles after their exposure, and different parameters were estimated to assess the oxidative stress induced by the instillation of MgO. Exposure of rats to MgO produced a significant (p MgO nanoparticle-exposed rats indicates the reduction in antioxidant defense mechanisms due to the instillation of MgO. These results indicate that exposure to MgO nanoparticles induces oxidative stress by reducing the total antioxidant capacity in rats. The findings suggest possible occupational health hazard in chronic exposures.

  9. [TG-FTIR study on pyrolysis of wheat-straw with abundant CaO additives].

    Science.gov (United States)

    Han, Long; Wang, Qin-Hui; Yang, Yu-Kun; Yu, Chun-Jiang; Fang, Meng-Xiang; Luo, Zhong-Yang

    2011-04-01

    Biomass pyrolysis in presence of abundant CaO additives is a fundamental process prior to CaO sorption enhanced gasification in biomass-based zero emission system. In the present study, thermogravimetric Fourier transform infrared (TG-FTIR) analysis was adopted to examine the effects of CaO additives on the mass loss process and volatiles evolution of wheat-straw pyrolysis. Observations from TG and FTIR analyses simultaneously demonstrated a two-stage process for CaO catalyzed wheat-straw pyrolysis, different from the single stage process for pure wheat-straw pyrolysis. CaO additives could not only absorb the released CO2 but also reduce the yields of tar species such as toluene, phenol, and formic acid in the first stage, resulting in decreased mass loss and maximum mass loss rate in this stage with an increase in CaO addition. The second stage was attributed to the CaCO3 decomposition and the mass loss and maximum mass loss rate increased with increasing amount of CaO additives. The results of the present study demonstrated the great potential of CaO additives to capture CO2 and reduce tars yields in biomass-based zero emission system. The gasification temperature in the system should be lowered down to avoid CaCO3 decomposition.

  10. SSC Model Fits to Simultaneous Fermi and CAO observations of Bl Lac's

    Science.gov (United States)

    Gordon, Tyler; Macomb, Daryl J.; Hand, Jared; Norris, Jay P.; Long, Min

    2016-01-01

    The Challis Astronomical Observatory (CAO) has been surveying a sample of blazar-type AGN since 2010. The CAO blazar sample includes4 3 sources - comprising 30 FSRQs, 15 BL Lacs, one radio galaxy and four unclassified sources - covering a redshift range 0.02 Potter and Cotter (MNRAS, 2012, 423, 756-765).

  11. On Interpreting the Photoelectron Spectra of MgO

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Arnold, James (Technical Monitor)

    2001-01-01

    The (sup 2)Sigma(+) and (sup 2)Pi states of MgO(-) and the (sup 1)Sigma(+), (sup 1)Pi, and (sup 3)Pi states of MgO are studied using the averaged coupled-pair functional (ACPF) approach. The computed spectroscopic constants are in good agreement with the available experimental data. The computed Franck-Condon factors and photodetachment overlaps are compared with experiment.

  12. Colloidal processing of alumina with MgO additions

    Energy Technology Data Exchange (ETDEWEB)

    Lyckfeldt, O. [Swedish Ceramic Inst., Goeteborg (Sweden); Ferreira, J.M.F. [Dept. of Ceramics and Glass Engineering, Univ. of Aveiro (Portugal)

    1997-12-31

    Both rheological studies and casting studies were made to evaluate the effects of adding MgO (0.10 wt%) to alumina slips with a solids loading of 45 vol%, stabilised either with a polyacrylic acid (Dispex A40, Allied Colloids Ltd, UK) or with a low M{sub w} sulphonic acid (Tiron, Aldrich Chemie, Germany). Tiron and Dispex are expected to give electrostatic and electrosteric stabilisation, respectively. The addition of MgO gave significant effects displayed by increased viscosity and elasticity of the slips and a considerable decrease in density of slip-cast and filter-pressed bodies. When the casting pressure increased, there was also a general tendency that the density of filter-pressed bodies decreased with well-stabilised slips (without MgO), but increased when the slip was weakly flocculated (with MgO). This was explained by the casting rate dependency under stabilised slip conditions, and the compressibility of the filter-pressed cakes formed using flocculated slips. Furthermore, it was shown that Tiron gave a higher degree of deflocculation both with addition of MgO and without MgO, indicating that the electrostatic stabilising mechanism dominates the particle interactions whereas steric effects are less important at the solids loading used. (orig.) 5 refs.

  13. Ordem e caos: um conceito alternativo de mercado

    Directory of Open Access Journals (Sweden)

    Édivo de Almeira Oliveira

    2016-01-01

    Full Text Available Mesmo constituindo-se um dos pilares de funcionamento do sistema capitalista, é bem verdade que o conceito de mercado não é consensual entre as distintas abordagens do pensamento econômico, dado as diferentes premissas e axiomas que fundamentam suas análises. Isto posto, o presente trabalho objetiva fornecer uma concepção holística e mais pragmática do mercado a partir dos conceitos de ordem espontânea, taxas naturais e expectativas racionais articulados com a Teoria do Caos. Com base nesses fundamentos teóricos conclui-se que o mercado é uma ordem espontânea evolutiva, repleta de relações não-lineares e formada por agentes autointeressados que, mediante processo de aprendizagem social, complexificam e aprimoram os padrões institucionais, culturais e técnicos que configuram o próprio mercado no transcorrer de um tempo dinâmico.

  14. Electrodeposition of Ca Metal in CaCl2-CaO Molten Salt

    Institute of Scientific and Technical Information of China (English)

    GUO; Jun-kang; WANG; Chang-shui; CAO; Long-hao; OUYANG; Ying-gen

    2013-01-01

    To realize the continuouscalciothermic reduction in molten salts,the electrodeposition behavior of Ca metal in CaCl2-CaO molten salt was investigated by cylic voltammetry.The cyclic voltammograms at the scan rate of 100 mV/s are shown in Fig.1.As is shown,the electrodeposition potential of Ca deviated from-1.66 V to-0.97 V after CaO was added to molten CaCl2 and the decomposition of CaO

  15. Reaction behavior of MgO in desilication process of sodium aluminate solution%氧化镁在铝酸钠溶液脱硅中的反应行为

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 齐天贵; 田侣; 周秋生; 彭志宏; 李小斌

    2013-01-01

    通过分析含硅铝酸钠溶液脱硅过程二氧化硅浓度、脱硅渣成分和物相,研究氧化镁在铝酸钠溶液中的反应行为。结果表明,在95~100℃的常压脱硅条件下,氧化镁在铝酸钠溶液中易形成水合碳铝酸镁,对溶液基本无脱硅效果,氧化铝损失较多,但氧化镁能显著促进石灰的脱硅作用,且在石灰用量一定时随氧化镁添加量的增加,溶液的脱硅率显著升高;在190℃的高压脱硅条件下,氧化镁对铝酸钠溶液石灰脱硅作用的促进不明显,但它可使脱硅渣的钠硅比(质量比)显著降低;无论是单独采用石灰(CaO),还是采用石灰和氧化镁混和物脱硅,含硅铝酸钠溶液高温脱硅渣中均含有钠硅渣相,这与热力学分析结果一致。%The reaction behavior of MgO in the desilication process of sodium aluminate solution was studied by analyzing SiO 2 concentration variation in solution and compositions and phases of the desilication slag. The results indicate that under desilication conditions of 95−100 ℃ and normal pressure, MgO can react with SiO 2-containing sodium aluminate solution to form the magnesium hydroaluminocarbonate and cause the loss of alumina. MgO has almost no desilication effect in the normal pressure desilication process, but it can promote the desilication rate of CaO significantly and the desilication rate increases with the increase of MgO amount when the dosage of CaO is constant. Under desilication conditions of 190 ℃ and high pressure, MgO has little effect on the desilication rate of CaO, but it can decrease the mass ratio of soda to silica of desilication slag. The sodium aluminosilicate hydrate is one of the main phases of the slags produced from high temperature desilication process with either MgO or mixture of MgO and CaO as desilication agent, which agrees with the result of thermodynamic calculation.

  16. Nonisothermal Thermogravimetric Analysis of Thai Lignite with High CaO Content

    Directory of Open Access Journals (Sweden)

    Pakamon Pintana

    2013-01-01

    Full Text Available Thermal behaviors and combustion kinetics of Thai lignite with different SO3-free CaO contents were investigated. Nonisothermal thermogravimetric method was carried out under oxygen environment at heating rates of 10, 30, and 50°C min−1 from ambient up to 1300°C. Flynn-Wall-Ozawa (FWO and Kissinger-Akahira-Sunose (KAS methods were adopted to estimate the apparent activation energy (E for the thermal decomposition of these coals. Different thermal degradation behaviors were observed in lignites with low (14% and high (42% CaO content. Activation energy of the lignite combustion was found to vary with the conversion fraction. In comparison with the KAS method, higher E values were obtained by the FWO method for all conversions considered. High CaO lignite was observed to have higher activation energy than the low CaO coal.

  17. Influence of NaCl-CaCl2 on Decomposing REPO4 with CaO

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The influence of NaCl-CaCl2 on thermal decomposition of REPO4 (RE: Ce, La, Nd, Th) with CaO was studied.The heat decomposing process of REPO4 was tested with TG-DTA experiments.The results showed that the decomposition temperature of REPO4 with CaO was reduced because of adding NaCl-CaCl2 mixture (NaCl:CaCl2=1:1).The influence of the addition of NaCl-CaCl2, roasting temperature and roasting time on decomposition ratio of REPO4 with CaO was studied.The results showed that the decomposition ratio of REPO4with CaO was 79% when the addition percentage of NaCl-CaCl2 was 10%, the roasting temperature was 750℃, and the roasting time was 1 h.

  18. [Academic heritage of Jiu huang ben cao (Materia Medica for Relief of Famines) in Japan].

    Science.gov (United States)

    He, Huiling; Xiao, Yongzhi

    2014-11-01

    Jiu huang ben cao (Materia Medica for Relief of Famines) was the first monograph on famines herbal in the history of China, which creates a new research field of edible plants. Around the middle and late 17th century, Jiu huang ben cao was spread to Japan and aroused great attention of famous Japanese herbalists. Thus, all versions of different edition systems were circulated in Japan. Later, some famous Japanese scholar ssuccessively quoted texts of Jiu huang ben cao from the Nong zheng quan shu (Whole book on Agricultural Administration) spread in Japan, and block-printed it as an independent work. As a result, Jiu huang ben cao virtually circulated widely in Japan.

  19. THERMODYNAMIC AND KINETIC PARAMETERS OF MIXTURES DESULFURIZING THE MADE WITH CaO, MgO, SiO2 AND CaF2

    Directory of Open Access Journals (Sweden)

    Felipe Nylo de Aguiar

    2012-09-01

    Full Text Available This paper presents an analysis of the kinetics and thermodynamics of marble residue mixtures utilisation on desulfurization of pig iron. The desulfurization was carried out using lime, marble residue, fluorite and pig iron. Different mixtures of these materials were added into a bath of pig iron at 1,450°C. Metal samples were collected via vacuum samplers at times of 5, 10, 15, 20 and 30 minutes, in order to check the variation of sulfur content. Based on the results of chemical analysis of the metal and the desulfurizer mixture, the sulfide capacity of mixtures, the sulfur partition coefficient and the sulfur mass transport coefficient values were calculated.The results show the technical feasibility of using marble waste as desulfurizer agent.

  20. Phase Composition and Thermal Expansion of CaO Stabilised ZrO2 Refactories

    Institute of Scientific and Technical Information of China (English)

    ZHAOShike; WUJingyuan; 等

    2000-01-01

    In this,phase compsition and thermal expansion behaviour of CaO Stabilised refractories were studied,Special attention was paid to the expasion behaviour of three materials with different phase composition,The research results indicated that the expansion behaviour could be improved by modifying the stabilization of ZrO2,which thus leads to the increase in the thermal shock resistance and possibly eroion resistace of as-obtained CaO stabilised ZrO material.

  1. Size effects in MgO cube dissolution.

    Science.gov (United States)

    Baumann, Stefan O; Schneider, Johannes; Sternig, Andreas; Thomele, Daniel; Stankic, Slavica; Berger, Thomas; Grönbeck, Henrik; Diwald, Oliver

    2015-03-10

    Stability parameters and dissolution behavior of engineered nanomaterials in aqueous systems are critical to assess their functionality and fate under environmental conditions. Using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we investigated the stability of cubic MgO particles in water. MgO dissolution proceeding via water dissociation at the oxide surface, disintegration of Mg(2+)-O(2-) surface elements, and their subsequent solvation ultimately leads to precipitation of Mg(OH)2 nanosheets. At a pH ≥ 10, MgO nanocubes with a size distribution below 10 nm quantitatively dissolve within few minutes and convert into Mg(OH)2 nanosheets. This effect is different from MgO cubes originating from magnesium combustion in air. With a size distribution in the range 10 nm ≤ d ≤ 1000 nm they dissolve with a significantly smaller dissolution rate in water. On these particles water induced etching generates (110) faces which, above a certain face area, dissolve at a rate equal to that of (100) planes.1 The delayed solubility of microcrystalline MgO is attributed to surface hydroxide induced self-inhibition effects occurring at the (100) and (110) microplanes. The present work underlines the importance of morphology evolution and surface faceting of engineered nanomaterials particles during their dissolution.

  2. Multifunctional MgO Layer in Perovskite Solar Cells.

    Science.gov (United States)

    Guo, Xudong; Dong, Haopeng; Li, Wenzhe; Li, Nan; Wang, Liduo

    2015-06-08

    A multifunctional magnesium oxide (MgO) layer was successfully introduced into perovskite solar cells (PSCs) to enhance their performance. MgO was coated onto the surface of mesoporous TiO(2) by the decomposition of magnesium acetate and, therefore, could block contact between the perovskite and TiO(2). X-ray photoelectron spectroscopy and infrared spectroscopy showed that the amount of H(2)O/hydroxyl absorbed on the TiO(2) decreased after MgO modification. The UV/Vis absorption spectra of the perovskite with MgO modification revealed an enhanced photoelectric performance compared with that of unmodified perovskite after UV illumination. In addition to the photocurrent, the photovoltage and fill factor also showed an enhancement after modification, which resulted in an increase in the overall efficiency of the cell from 9.6 to 13.9 %. Electrochemical impedance spectroscopy (EIS) confirmed that MgO acts as an insulating layer to reduce charge recombination.

  3. Experimental Study on Pore Distribution Characters and Convert Rate of CaO

    Institute of Scientific and Technical Information of China (English)

    Li JIA; Yanyan ZENG; Tao ZHANG

    2005-01-01

    During the reaction between calcium sorbents and SO2, calcium sorbents are first calcined and converted into CaO. CaO can be obtained by calcining Ca(OH)2 or CaCO3. The porosity of the sorbent is increased because of calcination and is decreased because of sulfurization. In the calcination process H2O or CO2 is escaped from the particles and pores are formed in particles. The reaction or convert rate of CaO is influenced strongly by the pore structure characters. From Ca(OH)2 to CaO the escape velocity of H2O or its mass transfer is one of the key factors influencing the pore forming. During calcination process different heating velocity, different heating time and temperature were suggested. The temperature rising rate and calcining temperature play important role to the pore structure. The convert rates of CaO obtained through different calcining conditions were investigated experimentally. Some interesting results were showed that the calcium utilization of CaO particles is determined not only by the special surface area and total pore volume, but also by pore-size distribution. The main factor influencing the sulfation is the pore diameter distribution at lower sulfation temperature. For higher reaction temperature specific volume is the important reason. But pore-size distribution is strongly influenced by heat flux and temperature in the calcining process.

  4. Inspiration that Cao Cao Humanism Management Thoughts to Modern Enterprise%曹操人本管理思想对现代企业的启示

    Institute of Scientific and Technical Information of China (English)

    黄巍

    2012-01-01

    Three kingdoms period, Cao Cao is leaders that cherish talents. His thinking of human capital control that only is uses and reward and punishment has a great effect on the later world. Cao Cao humanism management thoughts have enlightenment to improve the modern enterprise management ability. It requires enterprise managers to set up Bole consciousness and promote ability of commander, set up tolerant consciousness and overcome demand perfection on employment, set up respect consciousness and establish reward and punishment incentive mechanism talent.%曹操是三国时期著名的爱才惜才的领导人,他“唯才是举、因材授任、赏罚分明”的人力资本管控思想对后世影响深远。曹操人本管理思想对提升现代企业管理能力有诸多启示,它要求我们时下的企业管理者要树立“伯乐”意识,提升“将才”之能;要树立“包容”意识,克服“求全责备”的用人观;要树立“尊重”意识,建立“赏罚分明”的人才激励机制。

  5. Vickers hardness measurement of ion implanted MgO

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Y. (TRCRE, JAERI, 1233 Watanuki-machi, Takasaki, Gunma 370-12 (Japan)); Rueck, D.M. (Materialforschung, UNILAC, GSI, D-6100, Darmstadt (Germany)); Vogt, D. (Materialforschung, UNILAC, GSI, D-6100, Darmstadt (Germany)); Leible, K. (Materialforschung, UNILAC, GSI, D-6100, Darmstadt (Germany)); Khubeis, I. (University of Jordan, P.O. Box 13097, Amman (Jordan)); Meyer, O. (INFP, KfK, D-7500, Karlsruhe 1 (Germany))

    1994-06-01

    The Vickers hardness was measured for single crystals of MgO(100) implanted with 130 keV or 1.8 MeV Ar[sup +] ions and with 400 keV Xe[sup 2+] ions by means of the indentation technique with an applied load of 0.4-30 mN. Implantation with 130 keV Ar[sup +] and 400 keV Xe[sup 2+] gave similar results in hardening of MgO surface layers. In addition, the dose dependence of the measured hardness curve showed that a softening mechanism takes place at high doses. High energy implantation (1.8 MeV Ar[sup +]) made a hardened surface layer on MgO. This hardened layer also became softer at high doses. ((orig.))

  6. Fabrication of Single Crystal MgO Capsules

    Science.gov (United States)

    Danielson, Lisa

    2012-01-01

    A method has been developed for machining MgO crystal blocks into forms for containing metallic and silicate liquids at temperatures up to 2,400 C, and pressures up to at least 320 kilobars. Possible custom shapes include tubes, rods, insulators, capsules, and guides. Key differences in this innovative method include drilling along the crystallographic zone axes, use of a vibration minimizing material to secure the workpiece, and constant flushing of material swarf with a cooling medium/lubricant (water). A single crystal MgO block is cut into a section .5 mm thick, 1 cm on a side, using a low-speed saw with a 0.004 blade. The cut is made parallel to the direction of cleavage. The block may be cut to any thickness to achieve the desired length of the piece. To minimize drilling vibrations, the MgO block is mounted on a piece of adhesive putty in a vise. The putty wad cradles the bottom half of the entire block. Diamond coring tools are used to drill the MgO to the desired custom shape, with water used to wet and wash the surface of swarf. Compressed air may also be used to remove swarf during breaks in drilling. The MgO workpiece must be kept cool at all times with water. After all the swarf is rinsed off, the piece is left to dry overnight. If the workpiece is still attached to the base of the MgO block after drilling, it may be cut off by using a diamond cutoff wheel on a rotary hand tool or by using a low-speed saw.

  7. CAOS: the nested catchment soil-vegetation-atmosphere observation platform

    Science.gov (United States)

    Weiler, Markus; Blume, Theresa

    2016-04-01

    Most catchment based observations linking hydrometeorology, ecohydrology, soil hydrology and hydrogeology are typically not integrated with each other and lack a consistent and appropriate spatial-temporal resolution. Within the research network CAOS (Catchments As Organized Systems), we have initiated and developed a novel and integrated observation platform in several catchments in Luxembourg. In 20 nested catchments covering three distinct geologies the subscale processes at the bedrock-soil-vegetation-atmosphere interface are being monitored at 46 sensor cluster locations. Each sensor cluster is designed to observe a variety of different fluxes and state variables above and below ground, in the saturated and unsaturated zone. The numbers of sensors are chosen to capture the spatial variability as well the average dynamics. At each of these sensor clusters three soil moisture profiles with sensors at different depths, four soil temperature profiles as well as matric potential, air temperature, relative humidity, global radiation, rainfall/throughfall, sapflow and shallow groundwater and stream water levels are measured continuously. In addition, most sensors also measure temperature (water, soil, atmosphere) and electrical conductivity. This setup allows us to determine the local water and energy balance at each of these sites. The discharge gauging sites in the nested catchments are also equipped with automatic water samplers to monitor water quality and water stable isotopes continuously. Furthermore, water temperature and electrical conductivity observations are extended to over 120 locations distributed across the entire stream network to capture the energy exchange between the groundwater, stream water and atmosphere. The measurements at the sensor clusters are complemented by hydrometeorological observations (rain radar, network of distrometers and dense network of precipitation gauges) and linked with high resolution meteorological models. In this

  8. Enhanced boron adsorption onto synthesized MgO nanosheets by ultrasonic method.

    Science.gov (United States)

    Li, Ping; Liu, Chuang; Zhang, Li; Zheng, Shili; Zhang, Yi

    2017-01-01

    MgO nanosheets with high adsorption performance were fabricated by an ultrasonic method. It was revealed that, nest-like MgO was formed from the magnesium salt solution precipitation and further calcination. Then the nest-like MgO was exfoliated by ultrasonic waves to obtain MgO nanosheets with approximately a lateral of 200-600nm and a thickness of 10nm. Adjusting the ultrasonic time and power, the specific surface areas of MgO nanosheets could be tuned in a range of 79-168m(2)/g. The synthesized MgO nanosheets were used as adsorbents to remove boron from aqueous solution, and the maximum boron adsorption capacity of these MgO nanosheets reached 87mgg(-1). The high uptake capability of the MgO nanosheets makes it potentially adsorbent for the removal of boron from wastewaters.

  9. Lectin coated MgO nanoparticle: its toxicity, antileishmanial activity, and macrophage activation.

    Science.gov (United States)

    Jebali, Ali; Hekmatimoghaddam, Seyedhossein; Kazemi, Bahram; Allaveisie, Azra; Masoudi, Alireza; Daliri, Karim; Sedighi, Najme; Ranjbari, Javad

    2014-10-01

    The purpose of this research was to evaluate toxicity of uncoated magnesium oxide nanoparticles (MgO NPs), MgO NPs coated with Peanut agglutinin (PNA) lectin, and PNA alone on the promastigotes of Leishmania major (L. major) and macrophages of BALB/c mice. On the other hand, antileishmanial property of uncoated MgO NPs, lectin coated MgO NPs, and PNA lectin alone was evaluated, and also macrophage activation was investigated after treatment with these materials by measurement of nitrite, H2O2, and some interleukins. This study showed that PNA lectin and lectin coated MgO NPs had approximately no toxicity on L. major and macrophages, but some toxic effects were observed for uncoated MgO NPs, especially at concentration of 500 µg/mL. Interestingly, lectin coated MgO NPs had the highest antileishmanial activity and macrophage activation, compared with uncoated MgO NPs and PNA lectin.

  10. Low cost porous MgO substrates for oxygen transport membranes

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Søgaard, Martin; Clemens, F.

    2016-01-01

    This paper delineates the fabrication of porous magnesium oxide (MgO) ceramics with high porosity and gas permeability by warm pressing using pre-calcined MgO powder and fugitive pore former (combination of graphite and polymethyl methacrylate). Effect of pore former on the microstructure develop......O substrates were measured and correlated. Economic analysis of the MgO substrates was performed and it was found that MgO was much cheaper compared to perovskite and fluorite materials...

  11. New pyrometallurgical process of EAF dust treatment with CaO addition

    Institute of Scientific and Technical Information of China (English)

    Romchat Chairaksa-Fujimoto; Yosuke Inoue; Naoyoshi Umeda; Satoshi Itoh; Tetsuya Nagasaka

    2015-01-01

    The non-carbothermic zinc pyrometallurgical processing of electric arc furnace (EAF) dust was investigated on a laboratory scale. The main objective of this process was to convert highly stable zinc ferrite (ZnFe2O4), which accounts for more than half of total zinc in the EAF dust, into ZnO and Ca2Fe2O5 by CaO addition. The EAF dust was mixed with CaO powder in various ratios, pressed into pellets, and heated in a muffle furnace in air at temperatures ranging from 700 to 1100°C for a predetermined holding time. All ZnFe2O4 was transformed into ZnO and Ca2Fe2O5 at a minimum temperature of 900°C within 1 h when sufficient CaO to achieve a Ca/Fe molar ratio of 1.1 was added. However, at higher temperatures, excess CaO beyond the stoichiometric ratio was required because it was consumed by reactions leading to the formation of compounds other than ZnFe2O4. The evaporation of halides and heavy metals in the EAF dust was also studied. These components could be pref-erentially volatilized into the gas phase at 1100°C when CaO was added.

  12. Combined effects of Fenton peroxidation and CaO conditioning on sewage sludge thermal drying.

    Science.gov (United States)

    Liu, Huan; Liu, Peng; Hu, Hongyun; Zhang, Qiang; Wu, Zhenyu; Yang, Jiakuan; Yao, Hong

    2014-12-01

    Joint application of Fenton's reagent and CaO can dramatically enhance sludge dewaterability, thus are also likely to affect subsequent thermal drying process. This study investigated the synergistic effects of the two conditioners on the thermal drying behavior of sewage sludge and the emission characteristics of main sulfur-/nitrogen-containing gases. According to the results, Fenton peroxidation combined with CaO conditioning efficiently promoted sludge heat transfer, reduced the amounts of both free and bound water, and created porous structure in solids to provide evaporation channels, thus producing significant positive effects on sludge drying performance. In this case, the required time for drying was shortened to one-third. Additionally, joint usage of Fenton's reagent and CaO did not increase the losses of organic matter during sludge drying process. Meanwhile, they facilitated the formation of sulfate and sulfonic acid/sulfone, leading to sulfur retention in dried sludge. Both of Fenton peroxidation and CaO conditioning promoted the oxidation, decomposition, and/or dissolution of protein and inorganic nitrogen in sludge pre-treatment. As a consequence, the emissions of sulfurous and nitrogenous gases from dewatered sludge drying were greatly suppressed. These indicate that combining Fenton peroxidation with CaO conditioning is a promising strategy to improve drying efficiency of sewage sludge and to control sulfur and nitrogen contaminants during sludge thermal drying process.

  13. Position of Fe ions in MgO crystalline structure

    Directory of Open Access Journals (Sweden)

    Szczerba Jacek

    2015-03-01

    Full Text Available Magnesium oxide (MgO is one of the most important raw materials in many branches of industry. Magnesium oxide is a popular refractory raw material because of its high refractoriness and high resistance to basic slags and environment. In many cases, use of MgO is limited by its properties, especially the presence of secondary phases like iron oxides. The amount and distribution of iron oxides can strongly influence the technological properties of MgO and depend on the manufacturing method, particularly the heat-treatment process. The aim of the study was to evaluate the influence of the heat-treatment process on amount and distribution of iron ions in a magnesium oxide lattice. The 57Fe Mössbauer effect measurements of fused and sintered magnesium oxide samples doped by the iron oxide were conducted. Investigation reveals in both cases the presence of Fe2+ as well as Fe3+ ions. Fe2+ ions occupy Mg2+ octahedral sites in the MgO lattice, whereas the Fe3+ ions are located in highly distorted octahedral coordination. The amount of Fe2+ varies from around 66% for fused samples to 30% for sintered samples.

  14. Preparation and Characterization of Nano-polymer Porous MgO

    Institute of Scientific and Technical Information of China (English)

    Xue Liang ZHAI; Ai Dong ZHAO; Mi Ying JIA

    2004-01-01

    Porous carrier MgO which was aggregated by nano-particles has been firstly prepared by using a normal technology route. The MgO was rod-shaped and had large surface area. The factors which affect grain size and microstructure of MgO were explored.

  15. Nano-cube MgO formed on silicon substrate using pulsed laser deposition.

    Science.gov (United States)

    Kaneko, Satoru; Ito, Takeshi; Akiyama, Kensuke; Yasui, Manabu; Hirabayashi, Yasuo; Soga, Masayasu; Miyake, Yumiko; Yoshimoto, Mamoru

    2012-03-01

    Nano-cube MgO particles were formed on Si substrates by deposition of an MgO target using pulsed laser deposition method. An epitaxial film grows on Si(001) substrate with its contraction of lattice constants. In this study, expecting high quality MgO film, the MgO film prepared in the oxygen pressure ranging from 75-400 mTorr at the high temperature of -750 degrees C. The deposited MgO showed the growth of (001) preferred orientation on the Si(001) substrate. However, X-ray Photoelectron Spectroscopy (XPS) indicated the MgO film did not form a continuous film on the Si surface. Interestingly, the surface morphology observed by an Atomic Force Microscopy (AFM) showed nano-cube MgO particles scattered on the smooth surface of Si substrate. After annealing the nano-cube MgO, the shape of MgO particles were changed from nano-cube to round shaped particles. The AFM image of the surface showed round shaped MgO nanoparticles scattered on rough surface. X-ray Diffraction (XRD) revealed the epitaxial growth of MgO(001) with cubic on cubic arrangement on the Si(001) substrate (MgO[100] parallel to Si[100]).

  16. Effect of CaO content on residual stress of CAS glass-ceramic

    Institute of Scientific and Technical Information of China (English)

    XIE Jun; CHENG Jin-shu; LONG Xin-jiang; YANG Shu-zhen

    2006-01-01

    The mismatch in thermal expansion coefficient between crystalline phase and glass phase can result in large thermal stresses during thermal processing,as well as the low thermal conductivity,which is the most troublesome in the production of the CaO-Al2O3-SiO2 glass-ceramic. CaO content may influence the residual stress in the system. Therefore X-ray diffraction (XRD) 'sin2ψ' method was used to calculate the residual stress in samples containing various contents of CaO. The relationship between CaO content and residual stress in CAS system was investigated. Finally reasons causing such residual stress were analyzed.

  17. [Quantitative estimation of CaO content in surface rocks using hyperspectral thermal infrared emissivity].

    Science.gov (United States)

    Zhang, Li-Fu; Zhang, Xue-Wen; Huang, Zhao-Qiang; Yang, Hang; Zhang, Fei-Zhou

    2011-11-01

    The objective of the present paper is to study the quantitative relationship between the CaO content and the thermal infrared emissivity spectra. The surface spectral emissivity of 23 solid rocks samples were measured in the field and the first derivative of the spectral emissivity was also calculated. Multiple linear regression (MLR), principal component analysis (PCR) and partial least squares regression (PLSR) were modeled and the regression results were compared. The results show that there is a good relationship between CaO content and thermal emissivity spectra features; emissivities become lower when CaO content increases in the 10.3-13 mm region; the first derivative spectra have a better predictive ability compared to the original emissivity spectra.

  18. PROPERTIES OF CaO SINTERED WITH ADDITION OF ACTIVE ALUMINA

    Directory of Open Access Journals (Sweden)

    A. Miskufova

    2015-06-01

    Full Text Available This work provides research and evaluation of the influence of active gama alumina addition on green and sintered CaO material properties, microstructures and mineralogical phase formation. Experimental results have shown the possibility to prepare more stable CaO with excellent properties by energy saving one-stage burning process of natural ground limestone with small addition of γ-Al2O3 (1 wt. % at up to 1550oC for two hours. The additive caused increasing of the sintered density but especially significant decreasing of apparent porosity of CaO. X-ray diffraction and energy dispersive X-ray fluorescence analysis confirmed mainly the presence of 3CaO∙ Al2O3 on the grain boundaries. Formation of other phases during sintering, more specifically 12CaO∙7 Al2O3 and CaO∙6 Al2O3 with lower tendency to hydration was also proved.

  19. Simultaneous carbonation and sulfation of CaO in Oxy-Fuel CFB combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C. [School of Energy and Power Engineering, North China Electric Power University, Baoding City, Hebei Province (China); Jia, L.; Tan, Y. [CanmetENERGY, 1 Haanel Drive, Ottawa, Ontario, K1A 1M1 (Canada)

    2011-10-15

    For anthracites and petroleum cokes, the typical combustion temperature in a circulating fluidized bed (CFB) is > 900 C. At CO{sub 2} concentrations of 80-85 % (typical of oxy-fuel CFBC conditions), limestone still calcines. When the ash which includes unreacted CaO cools to the calcination temperature, carbonation of fly ash deposited on cool surfaces may occur. At the same time, indirect and direct sulfation of limestone also will occur, possibly leading to more deposition. In this study, CaO was carbonated and sulfated simultaneously in a thermogravimetric analyzer (TGA) under conditions expected in an oxy-fuel CFBC. It was found that temperature, and concentrations of CO{sub 2}, SO{sub 2}, and especially H{sub 2}O are important factors in determining the carbonation/sulfation reactions of CaO. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Desulphurization during VIM Refining Ni-base Superalloy using CaO Crucible

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The variation of S content during VIM refining Ni-base superalloy using CaO crucible was stud[ed. It was foundthat the desulphurization process could not be carried out by only using CaO crucible. The role of Al additionto desulphurization was also studied. Combining with the results of XRD and composition analysis of the CaOcrucible, the mechanism of desulphurization was proposed. Thermodynamical calculation about the reaction betweenthe interface of CaO crucible and liquid metal has been discussed. This work indicated that under proper refiningtechnology the S content in the liquid Ni-base alloy could be reduced from 3×10-5 to 2×10-6~4×10-6.

  1. An Exploration into the Cao Cao's Poem English Translation of Turtles Live long%四言古诗《龟虽寿》的英译初探

    Institute of Scientific and Technical Information of China (English)

    万兵

    2012-01-01

    There are varied versions of the English translation of the Chinese classical poem Turtles Live long,composed by Cao Cao, a famous poet and King of Wei in the Three Kingdoms era. Professor Zhao Yanchun's version, actually a trinity of imitation, consistency and variability, has a theoretical awareness con-cerning the translation of Chinese poetry into English.%三国诗人曹操《龟虽寿》的英译,已经有多个版本面世。赵彦春教授的译本独树一帜,其译品实为模仿性、一致性、变异性的三位一体,具有译诗理论上的自觉。

  2. Recovery of SO2 and MgO from By-Products of MgO Wet Flue Gas Desulfurization.

    Science.gov (United States)

    Yan, Liyun; Lu, Xiaofeng; Wang, Quanhai; Guo, Qiang

    2014-11-01

    An industrial demonstration unit using natural gas as a heat source was built to calcine the by-products of MgO wet flue gas desulfurization from power plants; influencing factors on the SO2 content in calciner gas were comprehensively analyzed; and an advantageous recycling condition of MgO and SO2 from by-products was summarized. Results showed that the SO2 content in the calciner gas was increased by more than 10 times under a lower excess air coefficient, a higher feed rate, a lower crystal water in by-products, and a higher feed port position. For the tests conducted under the excess air coefficient above and below one, the effect of the furnace temperature on the SO2 content in the calciner gas was reversed. Results of activity analysis indicate that particles of MgO generated under the calcination temperature of 900-1,000°C had a high activity. In contrast, due to the slight sintering, MgO generated under the calcination temperature of 1,100°C had a low activity. To recycle SO2 as well as MgO, a temperature range of 900-927°C for TE103 is proposed. These studies will prompt the desulfurization market diversification, reduce the sulfur's dependence on imports for making sulfuric acid, be meaningful to balance the usage of the natural resource in China, and be regarded as a reference for the development of this technology for other similar developing countries.

  3. Sustain and address discharge characteristics of AC-PDP with MgO surface coated by MgO nano crystal powders.

    Science.gov (United States)

    Kim, J H; Park, C S; Park, H D; Tae, H S; Lee, S H

    2013-05-01

    This paper examined the sustain and address discharge characteristics of ac-PDPs with MgO surface coated by MgO nano crystal powders. The MgO nano crystal powder was deposited by about 5% on the MgO surface by using the spray method. To investigate the effects of the partial addition of MgO nano crystal powders on the sustain discharge as well as the address discharge, the luminance, IR spectra of 823, 828 nm, cathodoluminance, and firing voltage were measured with the measurement of the address delay times and wall voltage variation in the 42-inch ac-PDP module with a high Xe content of 17%. As a result, the statistical delay characteristics were improved considerably especially under the low panel temperature of -5 degrees C for the MgO surface with MgO nano crystal powder. However, both MgO surfaces with and without the MgO nano crystal powder showed almost similar sustain and address discharge characteristics except the statistical delay characteristics.

  4. Application of Chinese Jun-Cao technique for the production of Brazilian Ganoderma lucidum strains

    Directory of Open Access Journals (Sweden)

    Leonardo do Nascimento Rolim

    2014-06-01

    Full Text Available Ganoderma lucidum is a medicinal mushroom traditionally used in China against a wide range of diseases such as cancer and also for its prevention. In this work, commercial Chinese strains G. lucidum were compared to wild Brazilian strains aiming to determine the cultivation potential through the use of Jun-Cao. Six formulations were tested and the strains presented good response to the applied method. In general, the mixture between the grass and wood was well suited for the basidiomycetes, contributing to the preparation of substrates that generated better results in Jun Cao.

  5. Bulk and surface properties of magnesium peroxide MgO2

    Science.gov (United States)

    Esch, Tobit R.; Bredow, Thomas

    2016-12-01

    Magnesium peroxide has been identified in Mg/air batteries as an intermediate in the oxygen reduction reaction (ORR) [1]. It is assumed that MgO2 is involved in the solid-electrolyte interphase on the cathode surface. Therefore its structure and stability play a crucial role in the performance of Mg/air batteries. In this work we present a theoretical study of the bulk and low-index surface properties of MgO2. All methods give a good account of the experimental lattice parameters for MgO2 and MgO bulk. The reaction energies, enthalpies and free energies for MgO2 formation from MgO are compared among the different DFT methods and with the local MP2 method. A pronounced dependence from the applied functional is found. At variance with a previous theoretical study but in agreement with recent experiments we find that the MgO2 formation reaction is endothermic (HSE06-D3BJ: ΔH = 51.9 kJ/mol). The stability of low-index surfaces MgO2 (001) (Es = 0.96 J/m2) and (011) (Es = 1.98 J/m2) is calculated and compared to the surface energy of MgO (001). The formation energy of neutral oxygen vacancies in the topmost layer of the MgO2 (001) surface is calculated and compared with defect formation energies for MgO (001).

  6. Los azules tigres del caos. Un vistazo al pensamiento de la complejidad en la obra de Jorge Luis Borges

    OpenAIRE

    Mata, Esteban

    2010-01-01

    El siguiente ensayo discute algunos temas relacionados con la ciencia dentro de la narrativa de Jorge Luis Borges; en especial aquellos concernientes a la teoría del caos y la dificultad -para el entendimiento humano- de discernir un orden en medio del caos, situación propia de todos los sistemas complejos.

  7. Phase Transitions of MgO Along the Hugoniot (Invited)

    Science.gov (United States)

    Root, S.; Shulenburger, L.; Lemke, R. W.; Cochrane, K. R.; Mattsson, T. R.

    2013-12-01

    The formation of terrestrial planets and planetary structure has become of great interest because of recent exoplanet discoveries of super earths. MgO is a major constituent of Earth's mantle, the rocky cores of gas giants such as Jupiter, and likely constitutes the interiors of many exoplanets. The high pressure - high temperature behavior of MgO directly affects equation of state models for planetary structure and formation. In this work, we examine single crystal MgO under shock compression utilizing experimental and density functional theory (DFT) methods to determine phase transformations along the Hugoniot. We perform plate impact experiments using Sandia's Z - facility on MgO up to 11.6 Mbar. The plate impact experiments generate highly accurate Hugoniot state data. The experimental results show the B1 - B2 solid - solid phase transition occurs near 4 Mbar on the Hugoniot. The solid - liquid transition is determined to be near 7 Mbar with a large region of B2-liquid coexistence. Using DFT methods, we also determine melt along the B1 and B2 solid phase boundaries as well as along the Hugoniot. The combined experimental and DFT results have determined the phase boundaries along the Hugoniot, which can be implemented into new planetary and EOS models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

  8. Finding fatigue resistant and lightweight designs using the optimization methods CAO and SKO

    Science.gov (United States)

    Mattheck, C.; Walther, Frank; Baumgartner, A.

    1992-07-01

    Computer Aided Optimization (CAO), a new method of shape optimization based on the computer simulation of biological growth and Soft Kill Option (SKO), and a strategy to find new design solutions with reduced weight are presented. CAO is used to improve the design of technical components by gaining a homogenized stress distribution on the surface of two and three dimensional finite element models. SKO helps to define new topologies starting from a general oversized 'design area'. With CAO it is also possible to simulate the 'adaptive growth' of biological load carriers, while SKO simulates the mineralization process of bones adapted to their loading. The main ideas of the methods are outlined and several examples of optimizations are shown. If completely new solutions for technical problems are desired, SKO is used first and the design proposal being found is then optimized by CAO in order to achieve a lightweight and fatigue resistant design. The efficiency of the combination of the two methods as a complete layout procedure is shown.

  9. Highly basic CaO nanoparticles in mesoporous carbon materials and their excellent catalytic activity.

    Science.gov (United States)

    Raja, Pradeep Kumar; Chokkalingam, Anand; Priya, Subramaniam V; Balasubramanian, Veerappan V; Benziger, Mercy R; Aldeyab, Salem S; Jayavell, Ramasamy; Ariga, Katsukiho; Vinu, Ajayan

    2012-06-01

    Highly basic CaO nanoparticles immobilized mesoporous carbon materials (CaO-CMK-3) with different pore diameters have been successfully prepared by using wet-impregnation method. The prepared materials were subjected to extensive characterization studies using sophisticated techniques such as XRD, nitrogen adsorption, HRSEM-EDX, HRTEM and temperature programmed desorption of CO2 (TPD of CO2). The physico-chemical characterization results revealed that these materials possess highly dispersed CaO nanoparticles, excellent nanopores with well-ordered structure, high specific surface area, large specific pore volume, pore diameter and very high basicity. We have also demonstrated that the basicity of the CaO-CMK-3 samples can be controlled by simply varying the amount of CaO loading and pore diameter of the carbon support. The basic catalytic performance of the samples was investigated in the base-catalyzed transesterification of ethylacetoacetate by aryl, aliphatic and cyclic primary alcohols. CMK-3 catalyst with higher CaO loading and larger pore diameter was found to be highly active with higher conversion within a very short reaction time. The activity of 30% CaO-CMK3-150 catalyst for transesterification of ethylacetoacetate using different alcohols increases in the following order: octanol > butanol > cyclohexanol > benzyl alcohol > furfuryl alcohol.

  10. Active Heterogeneous CaO Catalyst Synthesis from Anadara granosa (Kerang Seashells for Jatropha Biodiesel Production

    Directory of Open Access Journals (Sweden)

    Reddy ANR

    2017-01-01

    Full Text Available Heterogeneous catalysts are often used at large to produce biodiesel from non-edible vegetable crude oils such as Jatropha curcas oil (JCO. In this study, an active heterogeneous CaO catalyst was synthesized from a tropical biodiversity seashells Anadara granosa (A.granosa. The catalytic efficiency of A.granosa CaO was investigated in transesterification of JCO as biodiesel. The A.granosa CaO catalyst was synthesized using ‘Calcination – hydration – dehydration’ protocol. The spectral characterization of the catalyst were investigated by employing FT-IR, SEM, BET and BJH spectrographic techniques. The experimental design was executed with four reaction parameters that include catalyst concentration (CC, methanol ratio (MR, transesterification time (TT and reaction temperature (RT. The JCO transesterification reactions as well as impact of reaction parameters on the Jatropha biodiesel yield (JBY were analyzed. The sufficiency of the experimental results conformed through sequential validation tests, as a result, an average of 96.2% JMY was noted at optimal parametric conditions, CC of 3wt. %, TT of 120 min, MR of 5 mol. and RT of 60ºC at a constant agitation speed of 300rpm. An average JMY of 87.6% was resulted from the A.granosa CaO catalyst during their recycling and reuse studies up to third reuse cycle.

  11. Evaluation of antibacterial activity of plant mediated CaO nanoparticles using Cissus quadrangularis extract.

    Science.gov (United States)

    Marquis, Gowdhami; Ramasamy, Balagurunathan; Banwarilal, Sarkar; Munusamy, Ayyasamy Pudukadu

    2016-02-01

    An assessment of antibacterial activity of greenly synthesized nanoparticles using aqueous stem extract of Cissus quadrangularis was carried out. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, SEM, XRD, FTIR and further subjected for antibacterial activity against the pathogens Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae and Vibrio cholerae. The SEM photograph represents cubic and hexagonal shape of NPs about 58nm respectively whereas the XRD indicated the pure phase of the product and no impurity in peaks of well crystallized products. The FTIR spectrum of nanoparticles showed intensive peaks with blue shift indicating the crystalline and shorten the distance of crystal lattice. The plant mediated CaO nanoparticles showed maximum inhibition on E. coli followed by other strains. In MIC, the plant mediated CaO NPs possess high activity against all the test organisms whereas the CaCl2 and CaO compounds were moderately active. The approach to the synthesis of plant mediated CaO NPs has many advantages as scaled up, economic viability, etc. Application of such ecofriendly nanoparticles in bactericidal, wound healing and other medical applications makes this method potential existing for the large scale synthesis of the inorganic materials.

  12. Food selection in relation to nutritional chemistry of Cao Vit gibbons in Jingxi, China.

    Science.gov (United States)

    Ma, Changyong; Liao, Jiancun; Fan, Pengfei

    2017-01-01

    The Cao Vit gibbon (Nomascus nasutus) has only one population with about 110 individuals living in a degraded karst forest along the China-Vietnam border. Investigation of food choice in relation to chemical nutrition will offer important insights into its conservation. We studied the food choice of two groups of Cao Vit gibbons using instantaneous scan sampling in Bangliang National Nature Reserve, Guangxi, China, over 4 years, and analyzed the chemical components (total nitrogen, TN; water-soluble sugar, WSS; crude fat, CF; neutral detergent fiber, NDF; acid detergent fiber, ADF; acid detergent lignin, ADL; condensed tannin, CT; and ash) of 48 food plant parts and 22 non-food plant parts. Fruits and figs that are rich in sugar are important food resources for gibbons. For other food types, flowers are a good source of total nitrogen and carbohydrates, and leaves and buds provide sources of protein and minerals. Cao Vit gibbons selected fruits that contain less total nitrogen, less acid detergent fiber and more water-soluble sugar than non-food fruits. Several food species that were heavily consumed by Cao Vit gibbons are suggested as potential tree species for ongoing habitat restoration.

  13. CaO as Drop-In Colloidal Catalysts for the Synthesis of Higher Polyglycerols

    NARCIS (Netherlands)

    Kirby, Fiona; Nieuwelink, Anne Eva; Kuipers, Bonny W M; Kaiser, Anton; Bruijnincx, Pieter C A; Weckhuysen, Bert M.

    2015-01-01

    Glycerol is an attractive renewable building block for the synthesis of polyglycerols, which find application in the cosmetic and pharmaceutical industries. The selective etherification of glycerol to higher oligomers was studied in the presence of CaO colloids and the data are compared with those o

  14. Oxygen-vacancy driven tunnelling spintronics across MgO

    Science.gov (United States)

    Halisdemir, U.; Schleicher, F.; Kim, D. J.; Taudul, B.; Lacour, D.; Choi, W. S.; Gallart, M.; Boukari, S.; Schmerber, G.; Davesne, V.; Panissod, P.; Halley, D.; Majjad, H.; Henry, Y.; Leconte, B.; Boulard, A.; Spor, D.; Beyer, N.; Kieber, C.; Sternitzky, E.; Cregut, O.; Ziegler, M.; Montaigne, F.; Arabski, J.; Beaurepaire, E.; Jo, W.; Alouani, M.; Gilliot, P.; Hehn, M.; Bowen, M.

    2016-10-01

    The conservation of an electron's spin and symmetry as it undergoes solid-state tunnelling within magnetic tunnel junctions (MTJs) is thought to be best understood using MgO-based MTJs1. Yet the very large experimental values of tunnelling magnetoresistance (TMR) that justify this perception are often associated with tunnelling barrier heights well below those suggested by the MgO optical band gap. This combination of high TMR and low RA-product, while spawning spin-transfer/spin-orbit torque experiments and considerable industrial interest, cannot be explained by standard theory. Noting the impact of a tunnel barrier's altered stoichiometry on TMR2, we reconcile this 10+year-old contradiction between theory and experiment by considering the impact of the MgO barrier's structural defects3-5. We find that the ground and excited states of oxygen vacancies can promote localized states within the band gap with differing electronic character. By setting symmetry- and temperature-dependent tunnelling barrier heights, they alter symmetry-polarized tunnelling and thus TMR. We will examine how annealing, depending on MgO growth conditions, can alter the nature of these localized states. This oxygen vacancy paradigm of inorganic tunnelling spintronics opens interesting perspectives into endowing the MTJ with additional functionalities, such as optically manipulating the MTJ's spintronic response.

  15. Grain boundary mobility in anion doped MgO

    Science.gov (United States)

    Kapadia, C. M.; Leipold, M. H.

    1973-01-01

    Certain anions OH(-), F(-) and Gl(-) are shown to enhance grain growth in MgO. The magnitude of their effect decreases in the order in which the anions are listed and depends on their location (solid-solution, second phase) in the MgO lattice. As most anions exhibit relatively high vapor pressures at sintering temperatures, they retard densification and invariably promote residual porosity. The role of anions on grain growth rates was studied in relation to their effect on pore mobility and pore removal; the atomic process controlling the actual rates was determined from observed kinetics in conjunction with the microstructural features. With respect to controlling mechanisms, the effects of all anions are not the same. OH(-) and F(-) control behavior through creation of a defect structure and a grain boundary liquid phase while Cl(-) promotes matter transport within pores by evaporation-condensation. Studies on an additional anion, S to the minus 2nd power gave results which were no different from undoped MgO, possibly because of evaporative losses during hot pressing. Hence, the effect of sulphur is negligible or undetermined.

  16. Cytotoxic effects of MgO nanoparticles on human umbilical vein endothelial cells in vitro.

    Science.gov (United States)

    Ge, S; Wang, G; Shen, Y; Zhang, Q; Jia, D; Wang, H; Dong, Q; Yin, T

    2011-06-01

    The MgO nanoparticles are widely used in many fields. However, the toxicity of these nanoparticles to cells and organs remains fairly undiscovered. In this study, the cytotoxicity of MgO nanoparticles on human umbilical vein endothelial cells (HUVECs) in vitro was examined. The morphology and size of MgO nanoparticles were analysed by the transmission electron microscope (TEM) and nanoparticle size analyser. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 h-tetrazolium bromide) assay, 4',6-diamidino-2-phenylindole (DAPI) staining analysis, NO release and total antioxidation competence (T-AOC) assay were used to evaluate the cytotoxicity of MgO nanoparticles. The results showed that most MgO nanoparticles were spherical with agglomerated state and the diameter of single particle was about 100 nm. Meanwhile, low concentration (below 200 [micro sign]g/ml) of MgO nanoparticles suspension showed no cytotoxicity by MTT assay. However, once the concentration of MgO nanoparticles was higher than 500 [micro sign]g/ml, the relative growth rate was lower than the control. The DAPI staining analysis results showed no significant difference of the cells morphology between the groups with or without MgO nanoparticles. In addition, the MgO nanoparticles significantly enhanced the NO release and T-AOC content of the HUVECs. The testing results indicated that low concentration of MgO nanoparticles exhibited non-cytotoxicity.

  17. Effect of CaO doping on mechanical properties and thermal shock resistance of 10NiO-NiFe2O4 composite ceramics

    Institute of Scientific and Technical Information of China (English)

    LAI Yan-qing; ZHANG Yong; ZHANG Gang; TIAN Zhong-liang; LI Jie

    2008-01-01

    The CaO doped 10NiO-NiFe2O4 composite ceramics were prepared by the cold isostatic pressing-sintering process, and the effects of CaO content on the phase composition, mechanical property and thermal shock resistance of 10NiO-NiFe2O4 composite ceramics were studied. The results show that the samples mainly consist of NiO and NiFe2O4 when content of CaO is less than4%(mass fraction), bending strength increases obviously by CaO doping. Bending strength of the samples doped with 2% CaO is above 185 Mpa, but that of the samples without CaO is only 60 Mpa. Fracture toughness is improved obviously by CaO doping, the undoped ceramics. CaO doping is bad to thermal shock resistance of 10NiO-NiFe2O4 composite ceramics.

  18. Caos sensible : orden y caos en la construcción de los proyectos de creación en las artes plásticas

    OpenAIRE

    Rabazas Romero, Antonio

    2012-01-01

    Este estudio trata de establecer relaciones entre algunas conceptos que consideramos relevantes alrededor de las nociones de orden y caos. La elección viene justificada por su amplitud conceptual y su máxima transversalidad, pues se originan en la misma raíz del conocimiento. Dado que el Arte maneja realidades complejas y objetos confusos o mal definidos, consideramos importante el conocimiento y uso de estas nociones en un entorno de aprendizaje, a través de una óptica proyectual. Se plantea...

  19. Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

    Science.gov (United States)

    Jin, Tony; He, Yiping

    2011-12-01

    The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against Escherichia coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achieving more than 7 log reductions in bacterial counts. The antibacterial activity of MgO NP increased as the concentrations of MgO increased. A synergistic effect of MgO in combination with nisin was observed as well. However, the addition of ZnO NP to MgO NP did not enhance the antibacterial activity of MgO against both pathogens. Scanning electron microscopy was used to characterize the morphological changes of E. coli O157:H7 before and after antimicrobial treatments. It was revealed that MgO NP treatments distort and damage the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. These results suggest that MgO NP alone or in combination with nisin could potentially be used as an effective antibacterial agent to enhance food safety.

  20. Direct inelastic scattering of NO from MgO(100)

    Science.gov (United States)

    Kolodney, E.; Baugh, D.; Powers, P. S.; Reisler, H.; Wittig, C.

    1988-04-01

    Angular and internal state distributions are reported for NO molecules scattered from cleaved, single-crystal MgO(100) at several kinetic energies: 0.56⩾KE⩽0.90 eV, and surface temperatures: 300⩽ Ts⩽760 K. Rotational distributions can be characterized by low- and high- J "Boltzmann-like" components. When Ts=760 K, a pronounced increase in the high- J excitation was observed. NO(ν″=1) was undetectable ([ν″ = 1]/[ν″ =0] < 5×10 -3) at KE=0.76 eV and Ts=540 K.

  1. Adsorption of Ar on a nonuniform MgO surface

    Science.gov (United States)

    Hinman, D. C.; Halsey, G. D.

    1976-01-01

    Data are presented for the adsorption of Ar and N2 on a strongly heterogeneous MgO surface at 84 K and for Ar at a range of temperatures between 130 and 250 K. The high-temperature data are analyzed according to a model which separates the contributions to the potential into bulk and surface terms, providing a method for the determination of the surface area from parameters characteristic of the bulk material. A solid-gas energy parameter and parameters indicating the strength of the impurity sites are also evaluated.

  2. Non-isothermal Crystallization Kinetics of Spinels in Vanadium Slag with High CaO Content

    Science.gov (United States)

    Zhou, Wang; Xie, Bing; Tan, Wen-Feng; Diao, Jiang; Zhang, Xie; Li, Hong-Yi

    2016-09-01

    This paper investigated the non-isothermal crystallization kinetics of the spinel crystals in vanadium slags containing high CaO content. Experiments were performed in combination with theoretical calculation to address this issue, and statistical analyses based on the Crystal Size Distribution theory. The results indicate that low cooling rate and high CaO content benefit the growth of spinel crystals. The growth mechanism is revealed to be controlled by interface reactions and diffusion at the cooling rates of 5 K/min and 15 K/min, respectively. However, at higher temperatures (>1673 K), the growth of spinel crystals is controlled by nucleation. While the temperature is decreased to 1523 K at the cooling rate of 5 K/min, the mean diameter of spinel crystals could reach 36.44 μm. Experimental results combining with theoretical reveal that low cooling rate benefits spinels growth, especially for the interval of 1523 K-1200 K.

  3. El caos en los barrios de la frontera en la obra narrativa de L. H. Crosthwaite

    Directory of Open Access Journals (Sweden)

    Mara Donat

    2013-07-01

    Full Text Available If apocalypse is a metaphor of the end and the beginning of an age, collapse of cultural, political and social concepcions, construction of new identities and social realities, literature of “frontera norte de México” is good to realize an investigation of the biblical and mythical theme in postmodern sence. Colapsing any idea of legal and civil life in a national State, urban culture of “la Frontera” presents the social caos of ilegal and criminal conducts, as much es gendre violence and the political idea of national identity in crisis. México protagonize a contradiction between nacionalist pride, frontier defence and emigration to the Unites States, with apocalyptical implication these days. The narrative of Luis Humberto Crosthwaite permit to analyze the different representations of broken identity in the social caos of the frontier. The apocalypsis as inminent catastrophe, social insicurity and uncertain identity leads the individual to new urban and social representations.

  4. Kinetic study of CO2 reaction with CaO by a modified random pore model

    Directory of Open Access Journals (Sweden)

    Nouri S.M.M.

    2016-03-01

    Full Text Available In this work, a modified random pore model was developed to study the kinetics of the carbonation reaction of CaO. Pore size distributions of the CaO pellets were measured by nitrogen adsorption and mercury porosimetry methods. The experiments were carried out in a thermogravimeter at different isothermal temperatures and CO2 partial pressures. A fractional concentration dependency function showed the best accuracy for predicting the intrinsic rate of reaction. The activation energy was determined as 11 kcal/mole between 550–700°C. The effect of product layer formation was also taken into account by using the variable product layer diffusivity. Also, the model was successfully predicted the natural lime carbonation reaction data extracted from the literature.

  5. Screening of MgO- and CeO2-Based Catalysts for Carbon Dioxide Oxidative Coupling of Methane to C2+ Hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    Istadi; Nor Aishah Saidina Amin

    2004-01-01

    The catalyst screening tests for carbon dioxide oxidative coupling of methane (CO2-OCM)have been investigated over ternary and binary metal oxide catalysts. The catalysts are prepared by doping MgO- and CeO2-based solids with oxides from alkali (Li2O), alkaline earth (CaO), and transition metal groups (WO3 or MnO). The presence of the peroxide (O22-) active sites on the Li2O2, revealed by Raman spectroscopy, may be the key factor in the enhanced performance of some of the Li2O/MgO catalysts.The high reducibility of the CeO2 catalyst, an important factor in the CO2-OCM catalyst activity, may be enhanced by the presence of manganese oxide species. The manganese oxide species increases oxygen mobility and oxygen vacancies in the CeO2 catalyst. Raman and Fourier Transform Infra Red (FT-IR) spectroscopies revealed the presence of lattice vibrations of metal-oxygen bondings and active sites in which the peaks corresponding to the bulk crystalline structures of Li2O, CaO, WO3 and MnO are detected. The performance of 5%MnO/15%CaO/CeO2 catalyst is the most potential among the CeO2-based catalysts,although lower than the 2%Li2O/MgO catalyst. The 2%Li2O/MgO catalyst showed the most promising C2+ hydrocarbons selectivity and yield at 98.0% and 5.7%, respectively.

  6. Initial stages of CO2 adsorption on CaO: a combined experimental and computational study.

    Science.gov (United States)

    Solis, Brian H; Cui, Yi; Weng, Xuefei; Seifert, Jan; Schauermann, Swetlana; Sauer, Joachim; Shaikhutdinov, Shamil; Freund, Hans-Joachim

    2017-02-08

    Room temperature adsorption of carbon dioxide (CO2) on monocrystalline CaO(001) thin films grown on a Mo(001) substrate was studied by infrared reflection-absorption spectroscopy (IRAS) and quantum chemical calculations. For comparison, CO2 adsorption was examined on poorly ordered, nanoparticulate CaO films prepared on Ru(0001). For both systems, CO2 readily adsorbs on the clean CaO surface. However, additional bands were observable on the CaO/Ru(0001) films compared with CaO/Mo(001), because the stricter IRAS surface selection rules do not apply to adsorption on the disordered thin films grown on Ru(0001). Spectral evolution with increasing exposure of the IRA bands suggested the presence of several adsorption sites which are consecutively populated by CO2. Density functional calculations showed that CO2 adsorption occurs as monodentate surface carbonate (CO3(2-)) species at monatomic step sites and other low-coordinated sites, followed by formation of carbonates on terraces, which dominate at increasing CO2 exposure. To explain the coverage-dependent IRAS results, we propose CO2 surface islanding from the onset, most likely in the form of pairs and other chain-like species, which were calculated as thermodynamically favorable. The calculated adsorption energy for isolated CO2 on the terrace sites (184 ± 10 kJ mol(-1)) is larger than the adsorption energy obtained by temperature programmed desorption (∼120-140 kJ mol(-1)) and heat of adsorption taken from microcalorimetry measurements at low coverage (∼125 kJ mol(-1)). However, the calculated adsorption energies become less favorable when carbonate chains intersect on CaO terraces, forming kinks. Furthermore, our assignments of the initial stages of CO2 adsorption are consistent with the observed coverage effect on the CO2 adsorption energy measured by microcalorimetry and the IRAS results.

  7. Tricalcium phosphate based resorbable ceramics: Influence of NaF and CaO addition

    Energy Technology Data Exchange (ETDEWEB)

    Seeley, Zachary; Bandyopadhyay, Amit [W. M. Keck Biomedical Materials Research Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Bose, Susmita [W. M. Keck Biomedical Materials Research Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States)], E-mail: sbose@wsu.edu

    2008-01-10

    Resorbable bioceramics have gained much attention due to their time-varying mechanical properties in-vivo. Implanted ceramics degrade allowing bone in-growth and eventual replacement of the artificial material with natural tissue. Calcium phosphate based materials have caught the most significant attention because of their excellent biocompatibility and compositional similarities to natural bone. Doping these ceramics with various metal ions has significantly influenced their properties. In this study, tricalcium phosphate (TCP) compacts were fabricated via uniaxial compression with five compositions: (i) pure TCP, (ii) TCP with 2.0 wt.% NaF, (iii) TCP with 3.0 wt.% CaO, (iv) TCP with a binary of 2.0 wt.% NaF and 0.5 wt.% Ag{sub 2}O, and (v) TCP with a quaternary of 1.0 wt.% TiO{sub 2}, 0.5 wt.% Ag{sub 2}O, 2.0 wt.% NaF, and 3.0 wt.% CaO. These compacts were sintered at 1250 deg. C for 4 h to obtain dense ceramic structures. Phase analyses were carried out using X-ray diffraction. The presence of NaF in TCP improved densification and increased compression strength from 70 ({+-} 25) to 130 ({+-} 40) MPa. Addition of CaO had no influence on density or strength. Human osteoblast cell growth behavior was studied using an osteoprecursor cell line (OPC 1) to assure that the biocompatibility of these ceramics was not altered due to the dopants. For long-term biodegradation studies, density, weight change, surface microstructure, and uniaxial compression strength were measured as a function of time in a simulated body fluid (SBF). Weight gain in SBF correlated strongly with precipitation viewed in the inter-connected pores of the samples. After 3 months in SBF, all samples displayed a reduction in strength. NaF, CaO and the quaternary compositions maintained the most steady strength loss under SBF.

  8. 论曹文轩的文学观%On Cao Wenxuan's View of Literature

    Institute of Scientific and Technical Information of China (English)

    倪厚玉; 周宁

    2015-01-01

    Cao Wenxuan is one of the most powerful and influential writers in contemporary Chinese literary a-rena, for a series of expositions on literature made by him have been favorably conducive to enriching contemporary Chinese literary criticism theories.This paper aims to systematize and study the origin, formation and change of Cao Wenxuan's literature view and attempts to elucidate the connotation of his literature view with"beauty" and"aes-thetic perception" as its core so as to reveal Cao's idea and individuality in literary creation.%曹文轩是中国当代文坛最具实力与影响的作家之一.特别是他发表的一系列有关文学的论述对丰富当代文学批评理论具有良好的补给作用.论文将着重对曹文轩文学观的渊源、形成及流变进行系统梳理与研究,试图阐释以"美"和"美感"为核心的文学观内涵,从而揭示其独特的创作理念和创作个性.

  9. 曹乃谦小说中的女性%The Female in Cao Naiqian's Novel

    Institute of Scientific and Technical Information of China (English)

    赵海涛

    2015-01-01

    The woman palys an outstanding role in the stories of Cao Naiqian,the ebullient one,the merciful one,the kind one and the lonely one ,however,they are all the beautiful representatives.Cao always insisted on praising the wonderful woman in his stories,but these women's destiny are always tragedic, leaving people melancholy and regreful.And therefore,under such obivious contrast between the beauty and sadness,Cao's stories are beautiful with unique desolation.%女性在曹乃谦小说中的位置十分突出,她们有的多情大方,有的善良可爱,有的慈悲无私,有的孤苦伶仃,但不论怎样,她们都是一种美好的存在。曹乃谦在小说中一直坚持赞美女性,歌颂女性,把女性作为最美的诗与歌进行咏唱,但是这些女性的命运与结局却又总是以悲剧的形式出现,令人唏嘘惆怅。女性的美与悲之间的强烈反差,使曹乃谦的小说独具一种凄婉伤感之美。

  10. Intense ${^31-35}$Ar beams produced with a nanostructured CaO target at ISOLDE

    CERN Document Server

    Ramos, J P; Mendonça, T M; Seiffert, C; Senos, A M R; Fynbo, H O U; Tengblad, O; Briz, J A; Lund, M V; Koldste, G T; Carmona-Gallardo, M; Pesudo, V; Stora, T

    2014-01-01

    At the ISOLDE facility at CERN, thick targets are bombarded with highly energetic pulsed protons to produce radioactive ion beams (RIBs). The isotopes produced in the bulk of the material have to diffuse out of the grain and effuse throughout the porosity of the material to a transfer line which is connected to an ionizer, from which the charged isotopes are extracted and delivered for physics experiments. Calcium oxide (CaO) powder targets have been used to produce mainly neutron deficient argon and carbon RIBs over the past decades. Such targets presented unstable yields, either decaying over time or low from the beginning of operation. These problems were suspected to come from the degradation of the target microstructure (sintering due to high temperature and/or high proton intensity). In this work, a CaO microstructural study in terms of sintering was conducted on a nanostructured CaO powder synthesized from the respective carbonate. Taking the results of this study, several changes were made at ISOLDE i...

  11. CERN Technical Training 2002: Learning for the LHC! Introduction à la CAO CADENCE - French version only

    CERN Multimedia

    Davide Vitè

    2002-01-01

    Dans le cadre du suivi du programme ELEC-2002 : Electronics in HEP, une nouvelle session du cours Introduction à la CAO CADENCE. De la saisie de schéma Concept-HDL au PCB est programmée pour le 4 et 5 juin prochains. Le cours, en français, est gratuit et sera animé par Serge Brobecker de la division IT/PS/EAS. Objectif de cette formation est de donner une vue générale du système CAO CADENCE utilisé au CERN, et d'en connaître l'environnement et les possibilités, en acquérant des notions suffisantes pour utiliser la saisie de schéma. Le cours est ciblé pour une audience d'ingénieurs et techniciens désirant utiliser les outils CAO disponibles au CERN, afin de concevoir des circuits logiques et des circuits programmables digitaux. Plus d'information, et possibilité d'inscription par EDH sont accessibles depuis les pages «...

  12. Porous carbon material containing CaO for acidic gas capture: preparation and properties.

    Science.gov (United States)

    Przepiórski, Jacek; Czyżewski, Adam; Pietrzak, Robert; Toyoda, Masahiro; Morawski, Antoni W

    2013-12-15

    A one-step process for the preparation of CaO-containing porous carbons is described. Mixtures of poly(ethylene terephthalate) with natural limestone were pyrolyzed and thus hybrid sorbents could be easily obtained. The polymeric material and the mineral served as a carbon precursor and CaO delivering agent, respectively. We discuss effects of the preparation conditions and the relative amounts of the raw materials used for the preparations on the porosity of the hybrid products. The micropore areas and volumes of the obtained products tended to decrease with increasing CaO contents. Increase in the preparation temperature entailed a decrease in the micropore volume, whereas the mesopore volume increased. The pore creation mechanism is proposed on the basis of thermogravimetric and temperature-programmed desorption measurements. The prepared CaO-containing porous carbons efficiently captured SO2 and CO2 from air. Washing out of CaO from the hybrid materials was confirmed as a suitable method to obtain highly porous carbon materials.

  13. High photoelectron emission from Co-diffused MgO deposited using arc plasma gun

    Science.gov (United States)

    Yamamoto, Shin-ichi; Kosuga, Hiroki

    2015-08-01

    MgO has several advantageous characteristics and has been applied in various fields. In this study, we deposited Co nanoparticles in an island pattern on a Si substrate using an arc plasma gun (APG). We subsequently formed a MgO thin film on this substrate by metal-organic decomposition (MOD), which enables the formation of films in the atmosphere, thereby yielding a double-layer structure. The MgO thin film formed on Co nanoparticles deposited using the APG with 500 pulses of arc discharge exhibited improved crystallinity and photoelectron emission at least threefold higher than that of a MgO thin film formed directly without depositing Co nanoparticles. Although the transmittance of the specimen formed by depositing Co nanoparticles was initially 30% or lower, it increased to greater than 90% after the formation of the MgO thin film and the dispersion of the Co nanoparticles in the MgO thin film during heat treatment at 900 °C. Our results clarify that the characteristics of MgO thin films are markedly improved by depositing Co nanoparticles before forming the films. The results of Kelvin probe force microscopy (KPFM) indicate that the outermost surface of the Co material had become CoO (cobalt oxide) with the dispersion of Co nanoparticles in the MgO thin film. The lattice parameter of CoO nanoparticles (an-axis lattice parameter of 4.2615 Å) after heating matches well with that of MgO (4.2126 Å). The MgO thin films that grew in conjunction with the CoO nanoparticles were highly crystallized. We successfully established a high-performance, cost-effective bottom-up process that requires no ion injection by dispersing Co nanoparticles in a MgO thin film through heat treatment.

  14. Deep Fractionation of Ciinopyroxene in the East Pacific Rise 13°N: Evidence from High MgO MORB and Melt Inclusions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guoliang; ZENG Zhigang; YIN Xuebo; WANG Xiaoyuan; CHEN Daigeng

    2009-01-01

    Mid-ocean ridge basalts (MORBs) from East Pacific Rise (EPR) 13°N are analysed for major and trace elements, both of which show a continuous evolving trend. Positive MgO-Al2O3 and negative MgO-Sc relationships manifest the cotectic crystallization of plagioclase and olivine, which exist with the presence of plagioclase and olivine phenocrysts and the absence of clinopyroxene phenocrysts. However, the fractionation of clinopyroxene is proven by the positive correlation of MgO and CaO. Thus, MORB samples are believed to show a "clinopyroxene paradox". The highest magnesium.bearing MORB sample E13-3B (MGO=9.52%) is modelled for isobaric crystallization with COMAGMAT at different pressures. Observed CaO/Al2O3 ratios can be derived from E13-3B only by fractional crystallization at pressure >4±1 kbar, which necessitates clinopyroxene crystallization and is not consistent with cotectic crystallization of olivine plus plagioclase in the magma chamber (at pressure~1 kbar). The initial compositions of the melt inclusions, which could represent potential parental magmas, are reconstructed by correcting for post-entrapment crystallization (PEC). The simulated crystallization of initial melt inclusions also produce observed CaO/Al2O3 ratios only at >4±1 kbar, in which clinopyroxene takes part in crystallization. It is suggested that MORB magmas have experienced clinopyroxene fractionation in the lower crust, in and below the Moho transition zone. The MORB magmas have experienced transition from clinopyroxene+plagioclase+olivine crystallization at >4±1 kbar to mainly olivine+plagioclase crystallization at <1 kbar, which contributes to the explanation of the "clinopyroxene paradox".

  15. [Textual research on Costus root (Aucklandia lappa Decne) in the Sheng nong ben cao jing (Shennong's Classic of Materia Medica)].

    Science.gov (United States)

    Li, Guangyan; Wang, Dequn; Fang, Shiying; Xu, Maohong

    2014-05-01

    Aucklandia lappa Decne was first recorded in the Sheng nong ben cao jing (Shennong's Classic of Materia Medica). Through the textual research of herbal literature, it was found that the costus root in the Sheng nong ben cao jing perhaps was not the plant of Aucklandia lappa Decne of Compositae, but the eaglewood or Lignum Aquilasria Resinatum based on the comprehensive judgment of shape, taste, nature, and function etc. In the Sheng nong ben cao jing, it only includes costus root without the title of eaglewood, and Tao Hongjing recorded both herbs together in his Ming yi bie lu (Supplementary Records of Celebrated Physicians), which became a foreshadow of misunderstanding of the later generations. Beginning from the Tang ben cao (Materia Medica of the Tang Dynasty), the costus root was considered as the plant of Auckiandia lappa Decne from the Compostae with its profound influence until now.

  16. The Melting Curve and Premelting of MgO

    CERN Document Server

    Cohen, R E

    1996-01-01

    The melting curve for MgO was obtained using molecular dynamics and a non-empirical, many-body potential. We also studied premelting effects by computing the dynamical structure factor in the crystal on approach to melting. The melting curve simulations were performed with periodic boundary conditions with cells up to 512 atoms using the ab-initio Variational Induced Breathing (VIB) model. The melting curve was obtained by computing $% \\Delta H_m$ and agreement with previous estimates and we obtain a reasonable $\\Delta V_m$, but our melting slope dT/dP (114 K/GPa) is three times greater than that of Zerr and Boehler [1994] (35 K/GPa), suggesting a problem with the experimental melting curve, or an indication of exotic, non-ionic behavior of MgO liquid. We computed $S(q,\\omega )$ from simulations of 1000 atom clusters using the Potential Induced Breathing (PIB) model. A low frequency peak in the dynamical structure factor $% S(q,\\omega )$ arises below the melting point which appears to be related to the onset ...

  17. CaO nanocrystals grown over SiO2 microtubes for efficient CO2 capture: organogel sets the platform.

    Science.gov (United States)

    Prathap, Annamalai; Shaijumon, M M; Sureshan, Kana M

    2016-01-25

    Materials that can capture and store CO2 are important. Though CaO is a cheap sorbent, it is inefficient for practical purposes due to sintering and poor diffusion of CO2 through the surface-CaCO3 layer. We have developed a high performance, sintering-resistant CaO-based sorbent by uniformly nanofabricating the CaO nanocrystals on SiO2 microtubes made by organogel templated polymerization.

  18. Decomposition Reaction of Mixed Rare Earth Concentrate and Roasted with CaO and NaCl

    Institute of Scientific and Technical Information of China (English)

    Wu Wenyuan; Hu Guangyong; Sun Shuchen; Chen Xudong; Tu Ganfeng

    2004-01-01

    The reaction of the mixed rare earth concentrate including monazite ( REPO4 ) and bastnaesite ( REFCO3 )decomposed by CaO and NaCl additives at the temperature range from 100 to 1000 ℃ was studied by means of XRD and TG-DTA.The results show that when CaO and NaCl are not added, only REFCO3 can be decomposed at the temperature of 377 ~ 450 ℃.The decomposition products include REOF, RE2O3 and CeO2.However, REFCO3 can not be decomposed.When CaO is added, the decomposition reactions occur at the temperature range from 660 to 750 ℃.CaO has three decomposition functions: ( 1 ) REPO4 can be decomposed by CaO and the decomposition products include RE2O3 and Ca3 (PO4)2; (2) CaO can decompose REOF, and the decomposition products are RE2O3 and CaF2; (3)CaO can decompose REPO4 with CaF2, and the decomposition products are RE2 O3, Ca5 F( PO4 )3.The decomposition ratio of the mixed rare earth concentrate increased obviously, when CaO and NaC1 were added.NaC1 can supply the liquid for the reaction, improve the mass transfer process and accelerate the reaction.At the same time, NaC1 participated in the reaction that REPO4 was decomposed by CaO.

  19. Homegardens of the Cao Lan, a Tai-Speaking Ethnic Minority in Vietnam’s Northern Mountains

    OpenAIRE

    2015-01-01

    The Cao Lan are a Tai-speaking ethnic group living in the Midlands of Northern Vietnam. Homegardens are an important component of their agroecosystem. The ecological structures of each homegarden of 17 households of the Cao Ngoi village in Tuyen Quang province were described and modal patterns identified. Most homegardens have organically shaped planting areas with indeterminate boundaries, polycentric planting patterns, and contain multiple species within the same bed or planting area. All o...

  20. Mechanisms of antibacterial activity of MgO: non-ROS mediated toxicity of MgO nanoparticles towards Escherichia coli.

    Science.gov (United States)

    Leung, Yu Hang; Ng, Alan M C; Xu, Xiaoying; Shen, Zhiyong; Gethings, Lee A; Wong, Mabel Ting; Chan, Charis M N; Guo, Mu Yao; Ng, Yip Hang; Djurišić, Aleksandra B; Lee, Patrick K H; Chan, Wai Kin; Yu, Li Hong; Phillips, David Lee; Ma, Angel P Y; Leung, Frederick C C

    2014-03-26

    The toxicity of metal oxide nanomaterials and their antimicrobial activity is attracting increasing attention. Among these materials, MgO is particularly interesting as a low cost, environmentally-friendly material. The toxicity of MgO, similar to other metal oxide nanomaterials, is commonly attributed to the production of reactive oxygen species (ROS). We investigated the toxicity of three different MgO nanoparticle samples, and clearly demonstrated robust toxicity towards Escherichia coli bacterial cells in the absence of ROS production for two MgO nanoparticle samples. Proteomics data also clearly demonstrate the absence of oxidative stress and indicate that the primary mechanism of cell death is related to the cell membrane damage, which does not appear to be due to lipid peroxidation.

  1. Reduction-melting behaviors of boron-bearing iron concentrate/carbon composite pellets with addition of CaO

    Institute of Scientific and Technical Information of China (English)

    Jing-song Wang

    2015-01-01

    Although the total amount of boron resources in China is high, the grades of these resources are low. The authors have already proposed a new comprehensive utilization process of boron-bearing iron concentrate based on the iron nugget process. The present work de-scribes a further optimization of the conditions used in the previous study. The effects of CaO on the reduction–melting behavior and proper-ties of the boron-rich slag are presented. CaO improved the reduction of boron-bearing iron concentrate/carbon composite pellets when its content was less than 1wt%. Melting separation of the composite pellets became difficult with the CaO content increased. The sulfur content of the iron nugget gradually decreased from 0.16wt%to 0.046wt%as the CaO content of the pellets increased from 1wt%to 5wt%. CaO negatively affected the iron yield and boron extraction efficiency of the boron-rich slag. The mineral phase evolution of the boron-rich slag during the reduction–melting separation of the composite pellets with added CaO was also deduced.

  2. Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

    Science.gov (United States)

    The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against E. coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achievin...

  3. Ultrathin hexagonal MgO nanoflakes coated medical textiles and their enhanced antibacterial activity

    Science.gov (United States)

    Veeran Ponnuvelu, Dinesh; Selvaraj, Aravind; Prema Suriyaraj, Shanmugam; Selvakumar, Rajendran; Pulithadathail, Biji

    2016-10-01

    A facile hydrothermal method for development of ultrathin MgO nanoplates from different precursors and their enhanced antibacterial activity after coating onto medical textiles is reported. Ultrathin MgO nanoplates having hexagonal structure were characterized using UV-visible spectroscopy, atomic force microscopy, field emission scanning electron microscopy, x-ray diffraction and high resolution transmission electron microscopy. The formation of MgO nanoplates was found to exhibit profound anionic effect leading to ultrathin, planar structures with exposed MgO [111] facets, which may be responsible for enhanced antimicrobial activity. Medical fabrics (bleached 100% cotton) were coated with MgO nanoplates using pad-dry-cure method. The antibacterial activity of these fabrics was tested against Bacillus subtilis and Escherichia coli. The MgO nanoplates coated onto the fabric were found to have good adherence properties owing to their two-dimensional structure and were durable even after repeated washings without substantial reduction in the antimicrobial activity. The enhanced antibacterial activity may be attributed to the presence of oxygen vacancies, surface oxygen anions and hydroxyl groups on the surface of MgO nanoplates. This cost-effective functional finish (anti-microbial) to cotton fabric using MgO nanoplates may be suitable for many prospective medical applications and can serve as an alternative to the costlier silver based antimicrobial textiles.

  4. Autocatalytic surface hydroxylation of MgO(100) terrace sites observed under ambient conditions

    DEFF Research Database (Denmark)

    Newberg, J.T.; Mysak, E.R.; Bluhm, H.

    2011-01-01

    We have investigated the reaction of water vapor with the MgO(100) surface using ambient pressure X-ray photoelectron spectroscopy (AP-XPS), which permits the study of the chemical composition of the MgO/water vapor interface at p(H2O) in the Torr range. Water dissociation on thin MgO(100) films ...

  5. Low-pressure ETEM Studies of Au assisted MgO Nanorod Growth

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Damsgaard, Christian Danvad; Hansen, Thomas Willum;

    2014-01-01

    Environmental transmission electron microscopy (ETEM) studies MgO nanorod growth from Au catalyst nanoparticles in a controlled gas atmosphere have been performed, in order to elucidate the mobility of Au surface atoms and the configuration of the Au/MgO interface. MgO nanorod growth is driven...

  6. Evaporation mechanisms of MgO in laser assisted atom probe tomography

    KAUST Repository

    Mazumder, Baishakhi

    2011-05-01

    In this paper the field evaporation properties of bulk MgO and sandwiched MgO layers in Fe are compared using laser assisted Atom Probe Tomography. The comparison of flight time spectra gives an estimate of the evaporation times as a function of the wavelength and the laser energy. It is shown that the evaporation takes place in two steps on two different time scales in MgO. It is also shown that as long as the MgO layer is buried in Fe, the evaporation is dominated by the photon absorption in Fe layer at the tip apex. Eventually the evaporation process of MgO is discussed based on the difference between the bulk materials and the multilayer samples. © 2010 Elsevier B.V.

  7. Effective modification of MgO with surface transition metal oxides for NF3 decomposition

    Institute of Scientific and Technical Information of China (English)

    Yanan Wang; Xiufeng Xu; Pei Sheng; Hongguang Li; Tingting Wang; Youfen Huang; Fangshu Liu

    2011-01-01

    NF3 decomposition over transition metal oxides coated MgO reagents in the absence of water is investigated.The results show that NF3 can be decomposed completely over pure MgO but the time of NF3 steady full conversion kept as short as 80 min,while the reactivities of coated MgO reagents were remarkably enhanced by transition metal oxides,for example the time of NF3 complete conversion over 12%Fe/MgO extended to 380 min.It is suggested that not only an increase in surface area but also a significant enhancement in the fluorination of MgO substrate caused by the surface transition metal oxides result in an improved reactivity of coated MgO reagents for NF3 decomposition.

  8. Growth of MgO on multi-layered graphene and Mg in PVA matrix

    Science.gov (United States)

    Marka, Sandeep K.; Mohiddon, Md. Ahamad; Prasad, Muvva D.; Srikanth, Vadali V. S. S.

    2015-07-01

    An easy and low temperature in-situ growth of MgO micro-rods on multi-layered graphene (MLG) in poly vinyl alcohol (PVA) matrix is elucidated. MLG decked with nanosized fragments of MgO and PVA are used as the starting materials to form MgO micro-rods (width = ∼1 μm and length = ∼4 μm) and MLG filled PVA composite film. Simple solution mixing, spin coating and simple drying processes are used to obtain the PVA composite. The growth mechanism of MgO micro-rods and the role of PVA in the growth of MgO micro-rods are explained on the basis of the observed morphological, structural and phase characteristics and a further controlled synthesis experiment, respectively.

  9. Cellulose extraction from Zoysia japonica pretreated by alumina-doped MgO in AMIMCl.

    Science.gov (United States)

    Liu, Le; Ju, Meiting; Li, Weizun; Jiang, Yang

    2014-11-26

    In this study, alumina-doped MgO was produced as a solid alkali for lignocellulose pretreatment. Pretreatment with alumina-doped MgO disrupted the lignocellulose structure and significantly reduced the lignin content of the Z. japonica. After pretreatment, Z. japonica showed significant solubility in 1-allyl-3-methylimidazolium chloride (AMIMCl). The similar high solubility of pretreated Z. japonica samples by original alumina-doped MgO and used alumina-doped MgO also proved that alumina-doped MgO had strong stability, which can be recycled and used repeatedly. The regenerated cellulose was similar to microcrystalline cellulose according to FTIR and NMR analyses. Compared to microcrystalline cellulose, only the crystallinity of the regenerated cellulose decreased.

  10. Molecular dynamics study for the melting curve of MgO at high pressure

    Institute of Scientific and Technical Information of China (English)

    Liu Zi-Jiang; Cheng Xin-Lu; Zhang Hong; Cai Ling-Cang

    2004-01-01

    Shell-model molecular dynamics method is used to study the melting temperatures of MgO at elevated temperatures and high pressures using interaction potentials. Equations of state for MgO simulated by molecular dynamics are in good agreement with available experimental data. The pressure dependence of the melting curve of MgO has been calculated. The surface melting and superheating are considered in the correction of experimental data and the calculated values, respectively. The results of corrections are compared with those of previous work. The corrected melting temperature of MgO is consistent with corrected experimental measurements. The melting temperature of MgO up to 140GPa is calculated.

  11. Ultrathin MgO diffusion barriers for ferromagnetic electrodes on GaAs(001).

    Science.gov (United States)

    Sarkar, Anirban; Wang, Shibo; Grafeneder, Wolfgang; Arndt, Martin; Koch, Reinhold

    2015-04-24

    Ultrathin MgO(100) films serving as a diffusion barrier between ferromagnetic electrodes and GaAs(001) semiconductor templates have been investigated. Using Fe as an exemplary ferromagnetic material, heterostructures of Fe/MgO/GaAs(001) were prepared at 200 °C with the MgO thickness ranging from 1.5 to 3 nm. Structural characterization reveals very good crystalline ordering in all layers of the heterostructure. Auger electron spectroscopy depth-profiling and cross-sectional high-resolution transmission electron microscopy evidence diffusion of Fe into MgO and-for too thin MgO barriers-further into GaAs(001). Our results recommend a MgO barrier thickness larger than or equal to 2.6 nm for its application as a reliable diffusion barrier on GaAs(001) in spintronics devices.

  12. The role of MgO content in ex situ MgB2 wires

    DEFF Research Database (Denmark)

    Kovac, P.; Hugek, I.; Meligek, T.;

    2004-01-01

    An experimental study of the effect of MgO content in the MgB2 powder used for ex situ made composite wires was carried out. Two single-core MgB2/Fe/Cu wires were made using commercial MgB2 powders from Alfa Aesar containing different fraction of MgO. Critical temperature and critical currents...... of as-deformed and heat-treated wires were measured. The differences between the wires are discussed and correlated with the MgO content. It was found that by increasing the amount of MgO, the inter-grain connectivity worsens, but well distributed and low size MgO particles improve flux pinning....

  13. The electronic Raman spectrum of cobalt doped MgO

    Science.gov (United States)

    Walsh, D.; Trudel, J.; Chase, L. L.

    1984-09-01

    The energies of the 4T1 g states of Co 2+ as a dilute substitutional impurity in MgO relative to the ground Λ 6 g doublet have been found by low temperature Raman spectroscopy to be two Λ 8 g states at 305 ± 3 cm -1 and 930 ± 3 cm -1; the remaining Λ 7 g energy is predicted to be in the 980-1010 cm -1 range the corresponding Λ 6 g → Λ 7 g Raman transition being weak and buried in the extensive two-phonon background. A second-order perturbation calculation which couples the spin-orbit states to both E g and T2 g modes of vibration gives a weak but important Jahn-Teller stabilization energy for the Λ 8 g states.

  14. Fe nanoparticles embedded in MgO crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shalimov, Artem; Potzger, Kay; Talut, Georg; Reuther, Helfried; Zhou, Shengqiang; Baehtz, Carsten; Fassbender, Juergen [Forschungszentrum Dresden-Rossendorf, Bautzner Landstrasse 128, 01328 Dresden (Germany); Geiger, Dorin; Lichte, Hannes [Technical University, Dresden (Germany); Misiuk, Andrzej [Institute of Electron Technology, Warsaw (Poland); Stromberg, Frank [Universitaet Duisburg-Essen (Germany)

    2009-07-01

    Iron nanoparticles embedded in MgO crystals were synthesized by Fe{sup +} ion implantation at an energy of 100 keV and varying fluences from 3.10{sup 16} to 3.10{sup 17} cm{sup -2}. Investigations of structural and magnetic properties of Fe nanoparticles have been performed using magnetometry, X-ray diffraction, transmission electron microscopy and Moessbauer spectroscopy, as well as by theoretical Preisach modeling of bistable magnetic systems. It has been found that {alpha}- and {gamma}-Fe nanoparticles are formed for all fluences. The content of the {alpha}-Fe phase increases at higher fluences and after annealing. The influence of post-implantation annealing at 800 C in vacuum and under enhanced up to 10 kbar hydrostatic pressure in argon atmosphere on the formation of nanoparticles has been analyzed.

  15. New insight in oxidative conversion of alkanes : exploring Li-promoted MgO catalysts and plasma micro-reactors

    NARCIS (Netherlands)

    Trionfetti, Cristiano

    2008-01-01

    In this study the preparation of Li-promoted MgO catalysts is described using, respectively, (i) wet impregnation and (ii) sol-gel method. In the case of Li-promoted MgO catalysts, defects sites, due to the surface substitution of Mg2+ ions by a Li+ ion in the MgO matrix, are reported to play a sign

  16. A Redetermination of the Dissociation Energy of MgO(+)

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry

    1994-01-01

    In 1986, we reported a dissociation energy (D(sub 0) of 2.31 eV for the X(sup 2)Pi ground state of MgO(+). This value was determined by computing the dissociation energy to the Mg(2+) + O(-) limit and adjusting the value to the Mg(+) + O limit using the experimental Ionization Potential (IP) of Mg(+) and the Electron Affinity (EA) of O. The success of this method relies on the assumption that there is little covalent contribution to the bonding. The very small (0.04 eV) correlation contribution to the binding energy was taken as corroboration for the validity of this approach. Our earlier theoretical value was estimated to be accurate to at least 0.2 eV. It is in excellent agreement with the subsequent value of 2.30 +/- 0.13 eV determined by Freiser and co-workers from photodissociation experiments. It is also consistent with the upper (less than 3.1 eV) and lower (greater than 1.1 eV) bounds determined by Rowe obtained by studying the reactions of Mg(+) with 03 and NO2. However, it is inconsistent with an upper bound of 1.7 eV reported by Kappes and Staley based on their failure to observe MgO(+) in the reaction of Mg(+) with N2O. The picture became somewhat clouded, however, by the recent guided-ion beam mass spectrometric studies of Dalleska and Armentrout. Their initial analysis of the reaction data for Mg(+) + O2 lead to a bond dissociation energy of 2.92 +/- 0.25 eV, which is considerably larger than the value of 2.47 +/- 0.06 eV deduced from their studies of the Mg(+)+NO2 reaction.

  17. Viability of Clostridium sporogenes spores after CaO hygienization of meat waste.

    Science.gov (United States)

    Bauza-Kaszewska, Justyna; Paluszak, Zbigniew; Skowron, Krzysztof

    2014-01-01

    The occurrence of the pathogenic species C. perfringens and C. botulinum spores in animal by-products poses a potential epidemiological hazard. Strong entero- and neurotoxins produced by these bacteria adversely affect human health. To inactivate pathogens present in animal by-products, waste must be subjected to various methods of sanitization. The aim of the presented study was to estimate the effect of different doses of CaO on the viability of spores Clostridium sporogenes in meat wastes category 3. During the research, two doses of burnt lime were added to the poultry mince meat and meat mixed with swine blood contaminated with Clostridium sporogenes spore suspension. Half of the samples collected for microbiological analyses were buffered to achieve the pH level ~7, the other were examined without pH neutralization. To estimate the spore number, 10-fold dilution series in peptone water was prepared and heat-treated at 80 °C for 10 min. After cooling-down, one milliliter of each dilution was pour-plated onto DRCM medium solidified with agar. Statistical analysis were performed using the Statistica software. Application of 70% CaO caused complete inactivation of Clostridium spores in meat wastes after 48 hours. The highest temperature achieved during the experiment was 67 °C. Rapid alkalization of the biomass resulted in increasing pH to values exceeding 12. The effect of liming was not dependent on the meat wastes composition nor CaO dose. The experiment proved the efficiency of liming as a method of animal by-products sanitization. Application of the obtained results may help reduce the epidemiological risk and ensure safety to people handling meat wastes at each stage of their processing and utilization.

  18. Viability of Clostridium sporogenes spores after CaO hygienization of meat waste

    Directory of Open Access Journals (Sweden)

    Justyna Bauza-Kaszewska

    2014-09-01

    Full Text Available The occurrence of the pathogenic species [i]C. perfringens[/i] and [i]C. botulinum spores[/i] in animal by-products poses a potential epidemiological hazard. Strong entero- and neurotoxins produced by these bacteria adversely affect human health. To inactivate pathogens present in animal by-products, waste must be subjected to various methods of sanitization. The aim of the presented study was to estimate the effect of different doses of CaO on the viability of spores [i] Clostridium sporogenes[/i] in meat wastes category 3. During the research, two doses of burnt lime were added to the poultry mince meat and meat mixed with swine blood contaminated with [i]Clostridium sporogenes[/i] spore suspension. Half of the samples collected for microbiological analyses were buffered to achieve the pH level ~7, the other were examined without pH neutralization. To estimate the spore number, 10-fold dilution series in peptone water was prepared and heat-treated at 80 °C for 10 min. After cooling-down, one milliliter of each dilution was pour-plated onto DRCM medium solidified with agar. Statistical analysis were performed using the Statistica software. Application of 70% CaO caused complete inactivation of [i]Clostridium spores[/i] in meat wastes after 48 hours. The highest temperature achieved during the experiment was 67 °C. Rapid alkalization of the biomass resulted in increasing pH to values exceeding 12. The effect of liming was not dependent on the meat wastes composition nor CaO dose. The experiment proved the efficiency of liming as a method of animal by-products sanitization. Application of the obtained results may help reduce the epidemiological risk and ensure safety to people handling meat wastes at each stage of their processing and utilization.

  19. Chaumont 2004: disordine apparente, ordine reale: la teoria del caos e l’arte dei giardini

    Directory of Open Access Journals (Sweden)

    Claudia Maria Bucelli

    2015-11-01

    Full Text Available Nella sua tredicesima edizione il Festival Internazionale di Chaumont-sur-Loire propone uno dei temi di riflessione più avanzati della speculazione scientifica contemporanea, la Teoria del Caos. Chiamati a confrontarsi con un argomento già ampiamente oggetto di dibattiti scientifici e riflessioni filosofiche e artistiche, i 23 vincitori di quest’anno hanno allestito giardini sui quali si indaga sotto il profilo sia speculativo che intuitivamente creativo, ricercando una lettura trasversale, supportata dalle dirette testimonianze dei Concepteurs, delle complesse dinamiche teoriche e culturali alla base della contemporanea speculazione attorno al giardino. 

  20. "CAOS, COMPLEJIDAD, CREATIVIDAD: DISEÑANDO FRACTALES EN 'GERONIMO. AN AMERICAN LEGEND' DE WALTER HILL"

    OpenAIRE

    Rose Lema

    2010-01-01

    El objeto central del estudio consiste en analizar secuencias en el filme Geronimo. An American Legend del cineasta Walter Hill (1993), aplicando conceptos y procesos provenientes de las teorías del Caos, la Complejidad y la Creatividad. En la primera parte, se desarrollan y se caracterizan conceptos y términos caóticos, indicando cómo se van extrapolando hacia el campo cinematográfico: 1) el principio de la teoría de los tres cuerpos -proveniente principalmente de la astronomía-; 2) los fenó...

  1. Characterization of MgO powders for use in thermal batteries

    Energy Technology Data Exchange (ETDEWEB)

    Guidotti, R.A.; Reinhardt, W.

    1996-09-01

    Ten commercial MgO powders were evaluated for their suitability to act as a binder in the separator of thermal batteries to immobilize the electrolyte when it is molten. One brand in particular, Maglite S from Calgon, outperformed all the others. This report describes the results of a characterization study of this MgO as well as similar materials from other commercial vendors. The study objective was to define the critical properties of Maglite S MgO that are responsible for its superior performance in thermal-battery separators. Separator mixes were prepared with the various MgO powders and the resulting powders and pellets were characterized, to correlate key physical properties of these materials to select physical and chemical properties of the MgO powders used in their preparation. The MgO pore-size distribution was the only parameter that could be related to the deformation and electrolyte-leakage behavior of separator pellets. A potential replacement for the Maglite S is currently being qualified, since Maglite S MgO is no longer available.

  2. Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

    CERN Document Server

    Ma, B; Koritala, R E; Fisher, B L; Markowitz, A R; Erck, R A; Baurceanu, R; Dorris, S E; Miller, D J; Balachandran, U

    2003-01-01

    Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of approx 9deg was observed in the phi-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first approx 0.5 mu m from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the...

  3. Influence of different ions doping on the antibacterial properties of MgO nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Yuanyuan; Wang, Wei, E-mail: weiwang@hust.edu.cn; Tan, Fatang; Cai, Yuncheng; Lu, Junwen; Qiao, Xueliang

    2013-11-01

    Compared with other inorganic antibacterial agents, magnesium oxide (MgO) nanopowders exhibit a unique antibacterial mechanism and various advantages in applications, having attracted extensive attention. In this study, MgO nanopowders doped with different ions (Li{sup +}, Zn{sup 2+} and Ti{sup 4+}) were synthesized by a sol–gel method, respectively. The structures and morphologies of the as-obtained precursors and nanopowders were characterized and confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The influence of three metal ions doping on the antibacterial properties of MgO nanopowders was also investigated by their bactericidal activity against Escherichia coli (E. coli, ATCC 25922) using the broth microdilution method and the agar method. The results show that Li-doped MgO exhibits better antibacterial activity, Zn-doped and Ti-doped MgO display poorer antibacterial activity than pure MgO. It can be concluded that the influence of different ions doping on the antibacterial properties of MgO mainly lies on oxygen vacancies and basicity of nanopowders.

  4. Influence of different ions doping on the antibacterial properties of MgO nanopowders

    Science.gov (United States)

    Rao, Yuanyuan; Wang, Wei; Tan, Fatang; Cai, Yuncheng; Lu, Junwen; Qiao, Xueliang

    2013-11-01

    Compared with other inorganic antibacterial agents, magnesium oxide (MgO) nanopowders exhibit a unique antibacterial mechanism and various advantages in applications, having attracted extensive attention. In this study, MgO nanopowders doped with different ions (Li+, Zn2+ and Ti4+) were synthesized by a sol-gel method, respectively. The structures and morphologies of the as-obtained precursors and nanopowders were characterized and confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The influence of three metal ions doping on the antibacterial properties of MgO nanopowders was also investigated by their bactericidal activity against Escherichia coli (E. coli, ATCC 25922) using the broth microdilution method and the agar method. The results show that Li-doped MgO exhibits better antibacterial activity, Zn-doped and Ti-doped MgO display poorer antibacterial activity than pure MgO. It can be concluded that the influence of different ions doping on the antibacterial properties of MgO mainly lies on oxygen vacancies and basicity of nanopowders.

  5. Microstructural, optical and magnetic properties study of nanocrystalline MgO

    Science.gov (United States)

    Choudhury, Biswajit; Choudhury, Amarjyoti

    2014-04-01

    Nanocrystalline MgO is prepared by precipitation method. It has a crystallite size of 13 nm. The particles are agglomerated with varied size ranges. N2 adsorption-desorption isotherm confirms the mesoporous structure of MgO nanoparticles with a surface area of 145 m2 g-1. MgO contains hydride related impurities as evidenced from the Fourier transform infrared (FTIR) spectroscopy results. The UV-vis absorption spectrum of MgO contains several visible absorption peaks mostly associated with oxygen vacancies. These oxygen vacancies trap electrons and form color centers such as F, F +, F 2+, F 2 2+, etc. Photoluminescence (PL) and photoluminescence excitation (PLE) results have revealed that the UV and visible emission peaks of MgO result from these color centers. MgO also exhibits room temperature ferromagnetism. Vacuum annealing, however, reduces the magnetization. Thus, the observed magnetism may not be associated with oxygen vacancies. It is the Mg vacancy which is most likely promoting ferromagnetism in nanoscale MgO.

  6. Zn-catalytic growth and photoluminescence properties of branched MgO nanostructures

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Mass production of uniform MgO nanostructures has been achieved by a thermal evaporation method. X-ray diffraction (XRD) analyses show the product is composed of pure single-crystalline MgO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations show that the MgO branched nanostructures consist of many slim nanowires growing from the thick MgO rods. The as-synthesized nanowires have a length of several tens of microns and a diameter of several tens of nanometers. The preferred growth direction of the nanowires is [001]. Many nanowires are found to have a dendritic structure and temperature grade is thought to be the main cause of the growth of this structure. Zn nanoparticles scattered on the surface of the MgO rods are thought to be the catalyst of the VLS (vapor-liquid-solid) growth of the MgO nanowires. Room-temperature photoluminescence measurements show that the synthesized MgO nanostructures have a strong emission band at 401 nm and a weak emission band at 502 nm.

  7. Temperature-Dependent Morphology, Magnetic and Optical Properties of Li-Doped MgO

    Energy Technology Data Exchange (ETDEWEB)

    Myrach, Philipp [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Niklas, Nilius [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Levchenko, Sergey [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Gonchar, Anastasia [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Risse, Thomas [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Klaus-Peter, Dinse [Free University of Berlin; Boatner, Lynn A [ORNL; Frandsen, Wiebke [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Horn, Raimund [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Hans-Joachim, Freund [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Schlçgl, Robert [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Scheffler, Matthias [Fritz Haber Institute of the Max Planck Society, Berlin, Germany

    2010-01-01

    Li-doped MgO is a potential catalyst for the oxidative coupling of methane, whereby surface Li+ O centers are suggested to be the chemically active species. To elucidate the role of Li in the MgO matrix, two model systems are prepared and their morphological, optical and magnetic properties as a function of Li doping are investigated. The first is an MgO film deposited on Mo(001) and doped with various amounts of Li, whereas the second is a powder sample fabricated by calcination of Li and Mg precursors in an oxygen atmosphere. Scanning tunneling and transmission electron microscopy are performed to characterize the morphology of both samples. At temperatures above 700 K, Li starts segregating towards the surface and forms irregular Li-rich oxide patches. Above 1050 K, Li desorbs from the MgO surface, leaving behind a characteristic defect pattern. Traces of Li also dissolve into the MgO, as concluded from a distinct optical signature that is absent in the pristine oxide. No electron paramagnetic resonance signal that would be compatible with Li+O centers is detected in the two Li/ MgO samples. Density-functional theory calculations are used to determine the thermodynamic stability of various Li-induced defects in the MgO. The calculations clarify the driving forces for Li segregation towards the MgO surface, but also rationalize the absence of Li+O centers. From the combination of experimental and theoretical results, a detailed picture arises on the role of Li for the MgO properties, which can be used as a starting point to analyze the chemical behavior of the doped oxide in future.

  8. Epitaxial growth and properties of cubic WN on MgO(001), MgO(111), and Al{sub 2}O{sub 3}(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Ozsdolay, B.D. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Mulligan, C.P. [U.S. Army Armament Research Development & Engineering Center, Benet Laboratories, Watervliet, NY 12189 (United States); Guerette, Michael; Huang, Liping [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Gall, D., E-mail: galld@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2015-09-01

    Tungsten nitride layers, 1.45-μm-thick, were deposited by reactive magnetron sputtering on MgO(001), MgO(111), and Al{sub 2}O{sub 3}(0001) in 20 mTorr N{sub 2} at 700 °C. X-ray diffraction ω-2θ scans, ω-rocking curves, φ scans, and reciprocal space maps show that all layers exhibit a cubic rock salt structure, independent of their N-to-W ratio which ranges from x = 0.83–0.93, as determined by energy dispersive and photoelectron spectroscopies. Growth on MgO(001) leads to an epitaxial WN(001) layer which contains a small fraction of misoriented grains, WN(111)/MgO(111) is an orientation- and phase-pure single-crystal, and WN/Al{sub 2}O{sub 3}(0001) exhibits a 111-preferred orientation containing misoriented cubic WN grains as well as N-deficient BCC W. Layers on MgO(001) and MgO(111) with x = 0.92 and 0.83 have relaxed lattice constants of 4.214 ± 0.005 and 4.201 ± 0.031 Å, respectively, indicating a decreasing lattice constant with an increasing N-vacancy concentration. Nanoindentation provides hardness values of 9.8 ± 2.2, 12.5 ± 1.0, and 10.3 ± 0.4 GPa, and elastic moduli of 240 ± 40, 257 ± 13, and 242 ± 10 GPa for layers grown on MgO(001), MgO(111), and Al{sub 2}O{sub 3}(0001), respectively. Brillouin spectroscopy measurements yield shear moduli of 120 ± 2 GPa, 114 ± 2 GPa and 108 ± 2 GPa for WN on MgO(001), MgO(111) and Al{sub 2}O{sub 3}(0001), respectively, suggesting a WN elastic anisotropy factor of 1.6 ± 0.3, consistent with the indentation results. The combined analysis of the epitaxial WN(001) and WN(111) layers indicate Hill's elastic and shear moduli for cubic WN of 251 ± 17 and 99 ± 8 GPa, respectively. The resistivity of WN(111)/MgO(111) is 1.9 × 10{sup −5} and 2.2 × 10{sup −5} Ω-m at room temperature and 77 K, respectively, indicating weak carrier localization. The room temperature resistivities are 16% and 42% lower for WN/MgO(001) and WN/Al{sub 2}O{sub 3}(0001), suggesting a resistivity decrease with decreasing

  9. Initial reaction between CaO and SO2 under carbonating and non-carbonating conditions

    DEFF Research Database (Denmark)

    Rasmussen, Martin Hagsted; Wedel, Stig; Pedersen, Kim H.;

    2015-01-01

    The initial kinetics of the CaO/SO2 reaction have been investigated for reaction times shorter than 1s and in the temperature interval between 450 and 600°C under both carbonating and non-carbonating conditions (0-20 vol% CO2) to clarify how recirculating CaO influences the emission of SO2 from...... showed that the CaO conversion with respect to SO2 declined when the CO2 concentration was increased. Under all conditions, larger specific surface areas of CaO gave higher reaction rates with SO2. Higher temperatures had a positive effect on the reaction between SO2 and CaO under non...... a modern dry kiln preheater system for cement production. Calcined Faxe Bryozo limestone with a particle size smaller than 400μm was utilized as CaO source. It was shown, both theoretically and experimentally, that the observed reaction rates were influenced by mass transport limitations. The results...

  10. Spatial variability change of MgO content in Jelsava magnesite deposit (Slovakia)

    OpenAIRE

    J. Kondela; Jacko, S.; L. Vizi

    2017-01-01

    The presented paper deals with the study of the spatial variability changes of MgO content within the Jelšava magnesite deposit in Slovakia. The geostatistical structural analysis was used to study the spatial variability changes of the MgO content within three mining sectors A, B and C, localised in different parts of the deposit. The results show some important connections between the variability of MgO content and the structure setting of the deposit with utilization for the magnesite proc...

  11. Geometrical and Compositional Structure at Metal-Oxide Interfaces: MgO on Fe(001)

    Energy Technology Data Exchange (ETDEWEB)

    Meyerheim, H. L.; Popescu, R.; Kirschner, J.; Jedrecy, N.; Sauvage-Simkin, M.; Heinrich, B.; Pinchaux, R.

    2001-08-13

    The geometric structure of MgO deposited on Fe(001) in ultrahigh vacuum by electron evaporation was determined in detail by using surface x-ray diffraction. In contrast to the common belief that MgO grows in direct contact on the Fe(001) substrate, we find an FeO interface layer between the substrate and the growing MgO structure which has not been considered thus far. This result opens new perspectives for the understanding of the Fe/MgO/Fe(001) interface and the tunneling magnetoresistance effect in general.

  12. Relationship between alkaloid contents and growth environment of Yimu Cao (Herba Leonuri)

    Institute of Scientific and Technical Information of China (English)

    CHAO Zhi; YAN Gang

    2001-01-01

    To study the relationship between alkaloids contents in Chinese traditional drug Yimu Cao (the dried aerial parts ofLeonurus artemisia) and its growing environment. Methods: Samples of the drug and the soil at the growing site collected from 5 selected regions. Reference materials were checked and on-the-spot observations were carried out to investigate the growth environment. RP-HPLC was performed to determine the alkaloid contents in the drug. Results: Different regions had different environmental conditions, including climate, soil, vegetation, and so on.No matter barren or fertile the soil at the growing site was, the herb ofL. Artemisia could grow well, but the contents of alkaloid in the drug varied greatly. The drugs produced in 2 northern regions, where the soil is alkaline, had higher content of alkaloid (about 0.4%) than that produced in southern regions (0.1%-0.2%), where the soil is acid. Conclusion:The contents of organic matters, effective phosphorus, quick-acting potassium, and the pH value of the growing site soil were the factors correlating with alkaloid contents in the drug, among which the pH value of soil was an important positively correlating factor. The alkaline soils in North benefit the accumulation of alkaloids more than the acid soils in South. The other probable elements affecting the alkaloid contents in Yimu Cao were climate and genetic factors.

  13. The Experiences of e-Learning Implementation in CAO - Results of the Pilot Project

    Directory of Open Access Journals (Sweden)

    Zsuzsanna Vörös

    2010-12-01

    Full Text Available The various tasks of Central Agricultural Office are carried out by its central and regional directorates. For performing a high standard labour, well- and continuously educated team in needed, so the more thousands of colleagues working at central and regional levels have to be trained. Beside the traditional training forms – and built to them - there was a need for implementing a new distant teaching system, which provides a comprehensive distance education, resting on multimedia foundations, for the all colleagues of Central Agricultural Office working in different parts of the country and in different professional areas. The aim of our publication is to show how we introduced the e-Learning education within the distance education framework system of CAO, and to share our experiences obtained during the pilot training. The five courses of pilot training turned out a success: the results of examinations (the mean values: 84-91% and evaluations of questionnaires filled out by more than 200 colleagues taking part in training proved the entitlement of e-Learning education in CAO. However this method needs additional refinements in order to adapt to the specific requirements of andrology.

  14. Influence of hot isostatic pressing on ZrO2-CaO dental ceramics properties.

    Science.gov (United States)

    Gionea, Alin; Andronescu, Ecaterina; Voicu, Georgeta; Bleotu, Coralia; Surdu, Vasile-Adrian

    2016-08-30

    Different hot isostatic pressing conditions were used to obtain zirconia ceramics, in order to assess the influence of HIP on phase transformation, compressive strength, Young's modulus and density. First, CaO stabilized zirconia powder was synthesized through sol-gel method, using zirconium propoxide, calcium isopropoxide and 2-metoxiethanol as precursors, then HIP treatment was applied to obtain final dense ceramics. Ceramics were morphologically and structurally characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Density measurements, compressive strength and Young's modulus tests were also performed in order to evaluate the effect of HIP treatment. The zirconia powders heat treated at 500°C for 2h showed a pure cubic phase with average particle dimension about 70nm. The samples that were hot isostatic pressed presented a mixture of monoclinic-tetragonal or monoclinic-cubic phases, while for pre-sintered samples, cubic zirconia was the single crystalline form. Final dense ceramics were obtained after HIP treatment, with relative density values higher than 94%. ZrO2-CaO ceramics presented high compressive strength, with values in the range of 500-708.9MPa and elastic behavior with Young's modulus between 1739MPa and 4372MPa. Finally zirconia ceramics were tested for biocompatibility allowing the normal development of MG63 cells in vitro.

  15. The Sentimental Feelings in Cao Pi's Fu%论曹丕赋中的感伤情怀

    Institute of Scientific and Technical Information of China (English)

    张靖

    2012-01-01

    曹丕的赋具有很强的抒情性,由于特殊的政治地位和人生遭遇,使得曹丕在其赋中流露出凄凉哀婉的心境,以及孤立无援的精神状态,展现了曹丕精神世界中敏感脆弱的一面。%Cao Pi' s Fu has strong lyricism due to the special political status and life experience. Cao Pi in his ode re- veals the desolate pathos mood, as well as the isolated and helpless mental state, which shows Cao Pi' s spiritual world of fragile and sensitive side.

  16. Application of shell model in molecular dynamics simulation to MgO

    Institute of Scientific and Technical Information of China (English)

    Liu Zi-Jiang; Cheng Xin-Lu; Chen Xiang-Rong; Zhang Hong; Lu Lai-Yu

    2004-01-01

    The P-V-T equation of state of MgO has been simulated under high pressure and elevated temperature using the molecular dynamics (MD) method with the breathing shell model (BSM). It is found that the MD simulation with BSM is very successful in reproducing accurately the measured molar volumes of MgO over a wide range of temperature and pressure. In addition, the MD simulation reproduces accurately the measured volume compression data of MgO up to 100GPa at 300K. It is demonstrated that the MD simulated P-V-T equation of state of MgO could be applied as a useful internal pressure calibration standard at elevated temperatures and high pressures.

  17. Analysis of isothermal sintering of zinc-titanate doped with MgO

    Directory of Open Access Journals (Sweden)

    Obradović N.

    2007-01-01

    Full Text Available The aim of this work was analysis of isothermal sintering of zinc titanate ceramics doped with MgO obtained by mechanical activation. Mixtures of ZnO, TiO2 and MgO (0, 1.25 and 2.5% were mechanically activated 15 minutes in a planetary ball mill. The powders obtained were pressed under different pressures and the results were fitted with a phenomenological compacting equation. Isothermal sintering was performed in air for 120 minutes at four different temperatures. Structural characterization of ZnO-TiO2-MgO system after milling was performed at room temperature using XRPD measurements. DTA measurements showed different activation energies for pure and doped ZnO-TiO2 systems. Thus addition of MgO stabilizes the crystal structure of zinc titanate.

  18. Regenerable MgO promoted metal oxide oxygen carriers for chemical looping combustion

    Science.gov (United States)

    Siriwardane, Ranjani V.; Miller, Duane D.

    2014-08-19

    The disclosure provides an oxygen carrier comprised of a plurality of metal oxide particles in contact with a plurality of MgO promoter particles. The MgO promoter particles increase the reaction rate and oxygen utilization of the metal oxide when contacting with a gaseous hydrocarbon at a temperature greater than about 725.degree. C. The promoted oxide solid is generally comprised of less than about 25 wt. % MgO, and may be prepared by physical mixing, incipient wetness impregnation, or other methods known in the art. The oxygen carrier exhibits a crystalline structure of the metal oxide and a crystalline structure of MgO under XRD crystallography, and retains these crystalline structures over subsequent redox cycles. In an embodiment, the metal oxide is Fe.sub.2O.sub.3, and the gaseous hydrocarbon is comprised of methane.

  19. Assessment of pulmonary toxicity of MgO nanoparticles in rats.

    Science.gov (United States)

    Gelli, Kiranmai; Porika, Mahendar; Anreddy, Rama Narsimha Reddy

    2015-03-01

    In this study, we have evaluated the pulmonary toxicity of MgO nanoparticles (MgO NPs) in rats following their exposure. NPs in phosphate buffered saline + 1% Tween 80 were exposed via intratracheal instillation at a doses of 1 mg/kg or 5 mg/kg into rat lungs and evaluated for various tissue damage markers like alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid and histopathology of lungs at 1, 7, and 30 days of post-exposure intervals. A dose-dependant increase in ALP and LDH activity was observed in BAL fluids of rat lungs than sham control at all post-exposure periods (P MgO NPs. In conclusion, MgO NPs exposure produced a dose-dependent pulmonary toxicity in rats and was comparable with that of Quartz particles.

  20. Low-pressure Environmental TEM (ETEM) studies of Au assisted MgO nanorod growth

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Damsgaard, Christian Danvad; Hansen, Thomas Willum;

    2012-01-01

    where they become inactive for CO oxidation. Here, we present an environmental transmission electron microscopy (ETEM) study of shape changes of Au nanoparticles supported on MgO in a controlled gas atmosphere, in order to elucidate the mobility of surface species and the configuration of the Au....../MgO interface. The particles are synthesized by depositing a thin layer of Au onto MgO smoke particles. The Au agglomerates into particles that are a few nanometers in size, providing a model system for the investigation of nanoparticle surface and interface properties. Ajayan et al. [4], Kizuka [5......] and Nasibulin et al. [6] reported growth of nanorods on MgO smoke particles driven by the electron beam in high vacuum. However, the growth is strongly dependent on the gaseous environment. Here we investigate the relation between the surrounding environment and MgO nanorod growth. The electron beam induced...

  1. Strengthening and toughening of poly(L-lactide) composites by surface modified MgO whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Qin, Xiaopeng; Li, Cairong [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Liu, Mingxian; Ding, Shan [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

    2015-03-30

    Highlights: • The grafted PLLA chain on the surface of g-MgO whisker was ruled out by FTIR spectroscopy and TG/DTG analyses. • The excellent dispersion of g-MgO whiskers and the strong interfacial adhesion of g-MgO whiskers/PLLA composite were proved by FSEM. • Comparing to MgO particles and MgO whiskers, fibrous-like g-MgO whiskers are the most effective reinforcing and toughening fillers for PLLA. - Abstract: To improve both the strength and toughness of poly(L-lactide) (PLLA), fibrous-like MgO whiskers with diameters of 0.15–1 μm and lengths of 15–110 μm were prepared, and subsequently surface modified with L-lactide to obtain grafted MgO whiskers (g-MgO whiskers). The structures and properties of MgO whiskers and g-MgO whiskers were studied. Then, a series of MgO whiskers/PLLA and g-MgO whiskers/PLLA composites were prepared by solution casting method, for comparison, MgO particles/PLLA composite was prepared too. The resulting composites were evaluated in terms of hydrophilicity, crystallinity, dispersion of whiskers, interfacial adhesion and mechanical performance by means of polarized optical microscopy (POM), contact angle measurement, field emission scanning electron microscope (FSEM), transmission electron microscopy (TEM) and tensile testing. The results revealed that the crystallization rate and hydrophilicity of PLLA were improved by the introduction of MgO whiskers and g-MgO whiskers. The g-MgO whiskers can disperse more uniformly in and show stronger interfacial adhesion with the matrix than MgO whiskers as a result of the surface modification. Due to the bridge effect of the whiskers and the excellent interfacial adhesion between g-MgO whiskers and PLLA, g-MgO whiskers/PLLA composites exhibited remarkably higher strength, modulus and toughness compared to the pristine PLLA, MgO particles/PLLA and MgO whiskers/PLLA composites.

  2. Preparation of TiFe based alloys melted by CaO crucible and its hydrogen storage properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chong-he, E-mail: chli@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); He, Jin; Zhang, Zhao; Yang, Bo; Leng, Hai-yan [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Lu, Xiong-gang, E-mail: luxg@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); Li, Zhi-lin; Wu, Zhu [Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Hong-bin [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China)

    2015-01-05

    Highlights: • The home-made CaO crucible was used to prepare the TiFe based alloys. • The compositions as well as the content of oxygen can be effectively controlled. • The microstructure of the alloy melted by CaO crucible is dendrite. • The samples performed a good hydrogen storage performance. • The CaO crucible may be the promising candidate for melting the TiFe based alloys. - Abstract: The carbon contamination of alloys prepared by the electro graphite crucible is impossible to avoid due to the inherit reaction between the melt and the crucible. In this study, the TiFe-based alloy is prepared by VIM process using CaO crucible as well as the electro graphite crucible. The samples are examined by means of Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive Spectrometer (EDS), and the PCT curves are also measured. It is resulted that, the oxygen content of alloys melted by CaO crucible is almost equal to the one melted by graphite crucible and without the carbon contamination, meanwhile the carbon content of alloys obtained by the electro graphite crucible is 1860 ppm, which exceeds the tolerance of the commercial alloy (1000 ppm). The microstructure of the alloy melted by CaO crucible is dendrite, while it is composed of the equiaxed crystal with the lamellar structure and the spherical TiC particles distributed along grain boundaries or within the grain when melted by the graphite crucible; the interfacial reaction of the electro graphite crucible with TiFe alloy melt is serious and the interaction layer is formed up to 200 μm in thickness, the carbon in TiFe-based alloys forms TiC. The hydrogen desorption plateau pressure of alloys melted by CaO crucible is (0.11–0.4) × 10{sup 5} Pa, and that by the graphite crucible is (0.6–1) × 10{sup 5} Pa. This may imply that the CaO crucible may be the promising candidate for melting the high performance TiFe based hydrogen storage alloys.

  3. Pumping laser excited spins through MgO barriers

    Science.gov (United States)

    Martens, Ulrike; Walowski, Jakob; Schumann, Thomas; Mansurova, Maria; Boehnke, Alexander; Huebner, Torsten; Reiss, Günter; Thomas, Andy; Münzenberg, Markus

    2017-04-01

    We present a study of the tunnel magneto-Seebeck (TMS)4 effect in MgO based magnetic tunnel junctions (MTJs). The electrodes consist of CoFeB with in-plane magnetic anisotropy. The temperature gradients which generate a voltage across the MTJs layer stack are created using laser heating. Using this method, the temperature can be controlled on the micrometer length scale: here, we investigate, how both, the TMS voltage and the TMS effect, depend on the size, position and intensity of the applied laser spot. For this study, a large variety of different temperature distributions was created across the junction. We recorded 2D maps of voltages generated by heating in dependence of the laser spot position and the corresponding calculated TMS values. The voltages change in value and sign, from large positive values when heating the MTJ directly in the centre to small values when heating the junction on the edges and even small negative values when heating the sample away from the junction. Those zero crossings lead to very high calculated TMS ratios. Our systematic analysis shows, that the distribution of the temperature gradient is essential, to achieve high voltage signals and reasonable resulting TMS ratios. Furthermore, artefacts on the edges produce misleading results, but also open up further possibilities of more complex heating scenarios for spincaloritronics in spintronic devices.

  4. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many......Secondary creep of polycrystalline MgO with grain sizes of 100 and 190 μm was investigated at 1300° to 1460°C under compressive loads of 2.5 to 5.5 kgf/mm2. The dependence of creep rate on load follows a power law with an exponent of 3.2±0.3. The process is thermally activated, with an activation...... dislocation segments lie in their slip or climb planes. On the basis of this structure, a model is proposed in which glide is the principal cause of deformation but the rate-limiting process, i.e. annealing of the network, is diffusion-controlled. Theoretical estimates and experimental results agree within 1...

  5. Studying some mechanical properties of MgO with used neon bulb glass

    Energy Technology Data Exchange (ETDEWEB)

    Issa, Tarik Talib [University of Baghdad, College of science physic department , Material Science group (Iraq); Khaleel, Saba Mahdi [Ministry of Industry and Minerals,Commission for Research And Industrial Development ,Chemical and Petrochemical Research Center, Baghdad (Iraq); Abdul Kareem, Noura Ammar [Ministry of Industry and Minerals, Commission for Research And Industrial Development ,Chemical and Petrochemical Research Center, Baghdad (Iraq)

    2013-12-16

    Ceramic compact of MgO +WT% of UNBG were sintered at different sintering temperature (700, 900, 1100, 1300)°c, under static air for 3 hours. X-ray diffraction and some mechanical properties were conducted. The maximum sintered density, compression; fracture strength and hardness were indicated for the compilation of MgO −20 WT % UNBG, sintered at 1300 °c.

  6. Ab initio study of the low-lying electronic states of the CaO molecule

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Hossain; Brites, Vincent; Quere, Frederic Le [Universite Paris-Est, Laboratoire de Modelisation et Simulation Multi Echelle, UMR 8208 CNRS, Batiment Lavoisier, 5 boulevard Descartes, Champs sur Marne, 77454 Marne-la-Vallee, Cedex 2 (France); Leonard, Celine, E-mail: celine.leonard@univ-paris-est.fr [Universite Paris-Est, Laboratoire de Modelisation et Simulation Multi Echelle, UMR 8208 CNRS, Batiment Lavoisier, 5 boulevard Descartes, Champs sur Marne, 77454 Marne-la-Vallee, Cedex 2 (France)

    2011-07-28

    Graphical abstract: Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure of the low-lying electronic states of the CaO molecule. The computations are done using the aug-cc-pV5Z basis set for O and the cc-pCV5Z for Ca. The potential energy curves for the molecular states correlating to the lowest three asymptotes are calculated at the CASSCF level. The potential curves of the lowest five molecular states, X{sup 1}{Sigma}{sup +}, a{sup 3}{Pi}, A'{sup 1{Pi}}, b{sup 3}{Sigma}{sup +} and A{sup 1}{Sigma}{sup +}, and the corresponding dipole moment functions have been determined using internally contracted multi-reference configuration interaction approaches. The spectroscopic constants associated with these electronic states are compared to experimental values. The corresponding electronic wavefunctions have also been analyzed using the dipole moment functions. Display Omitted Highlights: {yields} The five lowest electronic states of Cao have been determined ab initio at a high level of accuracy. {yields} Large active space, core-valence correlation and configuration interaction are required. {yields} The multi-configurational nature of the electronic ground state is confirmed as well as its monovalent and divalent ionic nature using dipole moment analysis. {yields} These interacting potentials will serve for future obtention of spin-rovibronic levels. - Abstract: Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure of the low-lying electronic states of the CaO molecule. The computations are done using the aug-cc-pV5Z basis set for O and the cc-pCV5Z for Ca. The potential energy curves for the molecular states correlating to the lowest three asymptotes are calculated at the CASSCF level. The potential curves of the lowest five molecular states, X{sup 1}{Sigma}{sup +}, a{sup 3}{Pi}, A'{sup 1}{Pi}, b{sup 3}{Sigma}{sup +} and A{sup 1

  7. Synthesis and characterization of MgO nanocrystals for biosensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongji [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communication Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Qiu, Guojun [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Cuiping; Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communication Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2015-05-25

    Highlights: • MgO nanocrystals were prepared using DC arc plasma jet CVD method. • The growth time does not exceed 10 min in process of the synthesis. • The samples were found to consist of cubic MgO nanobelts and nanosheets. • Nanocrystals contain contacts, rough edges, vacancies, and doping defects. • The samples exhibited excellent electrochemical biosensing properties. - Abstract: MgO nanocrystals were prepared using a simple direct current arc plasma jet chemical vapor deposition method. Magnesium nitrate was used as source material and Mo film was used as a substrate and catalyst. The high-temperature plasma produced ensured rapid synthesis of the MgO nanocrystals. The as-prepared nanocrystals were characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, Fourier transform infrared spectrometry, ultraviolet–visible spectrophotometry, and photoluminescence measurements. The as-synthesized samples were found to consist of cubic MgO nanobelts and nanosheets with large surface areas and low coordination oxide ions, and contained numerous contacts, rough edges, vacancies, and doping defects. The nanostructures exhibited excellent electrochemical sensing properties with high-sensing sensitivity toward ascorbic acid. Their high electrocatalytic activity was attributed to the effect of defects and the surface electron transfer ability of the one-dimensional MgO nanobelts.

  8. Porous MgO material with ultrahigh surface area as the matrix for phase change composite

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yonggan; Shao, Xiankun; Liu, Tongxuan [School of Materials Science and Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Li, Benxia, E-mail: libx@mail.ustc.edu.cn [School of Materials Science and Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Nie, Shibin, E-mail: nsb@mail.ustc.edu.cn [School of Energy Resources and Safety, Anhui University of Science and Technology, Huainan, Anhui 232001 (China)

    2015-03-20

    Highlights: • Porous MgO material with ultrahigh surface area was synthesized. • A composite PCM was prepared from PEG-1000 and the porous MgO. • The phase change temperatures and enthalpy of the composite were measured. • The composite PCM performed good shape-stabilized property. - Abstract: Mesoporous magnesium oxide (MgO) material was synthesized using an integration of the evaporation-induced surfactant assembly and magnesium nitrate pyrolysis. The as-prepared MgO material is well crystalline, and possesses three-dimensional interconnected mesopores and a surface area as high as 596 m{sup 2}/g. Using the porous MgO as a matrix and polyethylene glycol (PEG-1000) as the functional phase for heat energy storage, a shape-stabilized phase change composite of PEG/MgO was fabricated by an easy impregnation method. In the composite, mesoporous MgO material provides structural strength and prevents the leakage of the molten PEG during the phase change process. The compositions and microstructures of the PEG/MgO composite were determined by Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD), scanning electronic microscope (SEM) and thermogravimetric analyzer (TGA), respectively. The phase change properties of the PEG/MgO composite were determined by differential scanning calorimeter (DSC). The high heat-energy storage capability and good thermal stability of the composite enable it extensive applications in the future.

  9. Effect of MgO nanofillers on burst release reduction from hydrogel nanocomposites.

    Science.gov (United States)

    Hezaveh, Hadi; Muhamad, Ida Idayu

    2013-06-01

    In this study, MgO nanoparticles are applied to control the initial burst release by modification of matrix structure, thereby affecting the release mechanism. The effects of MgO nanofiller loading on the in vitro release of a model drug are investigated. Surface topography and release kinetics of hydrogel nanocomposites are also studied in order to have better insight into the release mechanism. It was found that the incorporation of MgO nanofillers can significantly decrease the initial burst release. The effect of genipin (GN) on burst release was also compared with MgO nanoparticles, and it was found that the impact of MgO on burst release reduction is more obvious than GN; however, GN cross-linking caused greater final release compared to blanks and nanocomposites. To confirm the capability of nanocomposite hydrogels to reduce burst release, the release of β-carotene in Simulated Gastric Fluid and Simulated Intestinal Fluid was also carried out. Thus, the application of MgO nanoparticles seems to be a promising strategy to control burst release.

  10. Porphyrin Metalation at the MgO Nanocube/Toluene Interface.

    Science.gov (United States)

    Schneider, Johannes; Kollhoff, Fabian; Bernardi, Johannes; Kaftan, Andre; Libuda, Jörg; Berger, Thomas; Laurin, Mathias; Diwald, Oliver

    2015-10-21

    Molecular insights into porphyrin adsorption on nanostructured metal oxide surfaces and associated ion exchange reactions are key to the development of functional hybrids for energy conversion, sensing, and light emission devices. Here we investigated the adsorption of tetraphenyl-porphyrin (2HTPP) from toluene solution on two types of MgO powder. We compare MgO nanocubes with an average size d MgO cubes with 10 nm ≤ d ≤ 1000 nm. Using molecular spectroscopy techniques such as UV/vis transmission and diffuse reflectance (DR), photoluminescence (PL), and diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy in combination with structural characterization techniques (powder X-ray diffraction and transmission electron microscopy, TEM), we identified a new room temperature metalation reaction that converts 2HTPP into magnesium tetraphenyl-porphyrin (MgTPP). Mg(2+) uptake from the MgO nanocube surfaces and the concomitant protonation of the oxide surface level off at a concentration that corresponds to roughly one monolayer equivalent adsorbed on the MgO nanocubes. Larger MgO cubes, in contrast, show suppressed exchange, and only traces of MgTPP can be detected by photoluminescence.

  11. Study on the Surface Free Energy of Ground CaO by IGC

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    CaO formed by decomposing CaCO3 at 1450℃ was ground in a vibrational mill,then the long-time ground sample was reheated at different temperatures.Inverse Gas Chromatography (IGC) was used to measure the variation of the sample′s surface free energy under grinding and reheating.It is concluded that the total surface free energy and the London dispersive component of the surface free energy increases with grinding,while the polar component first increases with grinding,and then decreases,and finally disappears.When the long-time ground sample was reheated,its total surface free energy decreases,among which the London component decreases,but the polar component appears again.

  12. Caos, complexidade e Lingüística Aplicada: diálogos transdisciplinares

    Directory of Open Access Journals (Sweden)

    Antônio Carlos Soares Martins

    2007-01-01

    Full Text Available Neste texto, apresentamos um panorama de estudos na área da Lingüística Aplicada que discutem questões relativas ao processo de desenvolvimento de segunda língua, bem como aspectos relacionados aos ambientes interacionais de aprendizagem na perspectiva das teorias do Caos e Complexidade. Para isso, discutimos as principais noções da perspectiva da complexidade, retomando alguns aspectos da física clássica e contemporânea.In this paper, we present a panorama of studies in the area of Applied Linguistics that discuss questions regarding second language development as well as aspects related to interactional learning environments in the light of Chaos and Complexity theories. To accomplish this, we discuss the main notions of complexity through the rethinking of some aspects of classic and contemporary physics.

  13. Teoría del caos, cognitivismo y semántica

    Directory of Open Access Journals (Sweden)

    Lic. Raymond Colle

    1998-01-01

    Full Text Available El origen del pensamiento no tiene nada de secuencial: el cerebro es un "mecanismo" que opera con una altísima tasa de paralelismo. Es también un sistema altamente complejo y comparte algunas características de funcionamiento de todos los sistemas altamente complejos. En este artículo se citan a diversos investigadores que han puesto en evidencia los fenómenos de aparición del orden en medio del "caos" en sistemas complejos; se explica cómo el pensamiento se ordena en torno a "atractores", formando "mapas" de relaciones y se ilustra con un caso practico cómo este mapa aparece en nuestros discursos.

  14. Thermoluminescence properties of gamma irradiated CaO: Sm{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, D. [Physics R& D Center, PES Institute of Technology, 100 ft. Ring Road, BSK 3rd Stage, Bangalore 560085 (India); Department of Physics, Government Science College, Bangalore 560001 (India); Nagabhushana, K.R., E-mail: bhushankr@gmail.com [Physics R& D Center, PES Institute of Technology, 100 ft. Ring Road, BSK 3rd Stage, Bangalore 560085 (India); Department of Physics - S& H, PES University, Bangalore 560085 (India)

    2016-07-15

    Pure and samarium doped calcium oxide (CaO) is synthesized by solution combustion technique. The samples are annealed at 600 °C for two hours. X-ray diffraction (XRD) pattern of the annealed sample show cubic phase with space group Fm3m. The average crystallite size is found to be ∼54 nm. Fourier transform infra red (FTIR) spectrum exhibits bands at 424, 544 cm{sup −1} (Ca–O bond), 875 cm{sup −1} (C–O bond), 1460 cm{sup −1} (C–O stretch) and 3640 cm{sup −1} (O–H stretch). The samples are irradiated with gamma rays in a dose range 100–4000 Gy. Thermoluminescence (TL) glow curves are recorded at a linear heating rate (β) of 5 Ks{sup −1}. A prominent TL glow with a peak at 636 K is observed in undoped sample. A new TL glow with peak at ∼458 K is observed in addition to 636 K in samarium doped (1 mol%) CaO. TL glow peak intensity (I{sub max}) at 636 K increases with γ – dose in the study range. TL emissions at 560, 600 and 640 nm are observed in doped samples corresponding to Sm{sup 3+} transitions along with pristine emissions. TL glow curves are deconvoluted to obtain kinetic parameters. The mean value of activation energy and the frequency factor of the prominent deconvoluted TL glow peak (626 K) are found to be 1.26 eV and 4.49 × 10{sup 9} s{sup −1} respectively.

  15. DUSTER: collection of meteoric CaO and carbon smoke particles in the upper stratosphere .

    Science.gov (United States)

    Della Corte, V.; Rietmeijer, F. J. M.; Rotundi, A.; Ferrari, M.; Palumbo, P.

    Nanometer- to micrometer-size particles present in the upper stratosphere are a mixture of terrestrial and extra-terrestrial origins. They can be extraterrestrial particles condensed after meteor ablation. Meteoric dust in bolides is occasionally deposited into the lower stratosphere around 20 km altitude. Nanometer CaO and pure carbon smoke particles were collected at 38 km altitude in the upper stratosphere in the Arctic during June 2008 using DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval), a balloon-borne instrument for the non-destructive collection of solid particles between 200 nm to 40 microns. We report the collection of micron sized CaCO_3 (calcite) grains. Their morphologies show evidence of melting and condensation after vaporization suggest at temperatures of approximately 3500 K. The formation environment of the collected grains was probably a dense dust cloud formed by the disintegration of a carbonaceous meteoroid during deceleration in the Earth� atmosphere. For the first time, DUSTER collected meteor ablation products that were presumably associated with the disintegration of a bolide crossing the Earth's atmosphere. The collected mostly CaO and pure carbon nanoparticles from the debris cloud of a fireball, included: 1) intact fragments; 2) quenched melted grains; and 3) vapor phase condensation products. The DUSTER project was funded by the Italian Space Agency (ASI), PRIN2008/MIUR (Ministero dell'Istruzione dell'Universitá e della Ricerca), PNRA 2013(Piano Nazionale Ricerca Antartide). CNES graciously provided this flight opportunity. We thank E. Zona and S. Inarta at the Laboratorio di Fisica Cosmica INAF, Osservatorio Astronomico di Capodimonte-Universitá di Napoli Parthenope. F.J.M.R. was supported by grant NNX07AI39G from the NASA Cosmochemistry Program. We thank three anonymous reviewers who assisted us in introducing our new instrument.

  16. CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, IL (United States)

    1996-10-01

    The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464{degrees}C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating {approx}7-8 {mu}m thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10{sup 10} {Omega}-cm{sup 2} at 300{degrees}C and 400 h, and 0.9 x 10{sup 10} {Omega}-cm{sup 2} at 464{degrees}C and 300 h. Thermal cycling between 300 and 464{degrees}C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased.

  17. La anticipación de las crisis (una aplicación del enfoque del caos

    Directory of Open Access Journals (Sweden)

    Manuel Guzmán Hennessey

    2007-01-01

    Full Text Available Este ensayo explora la posibilidad de aplicar la teoría del caos en el contexto de las dinámicas de crisis. Se examinan las bases filosóficas del pensamiento cognitivo borroso y se explora un modelo de aproximación a la realidad, a partir del reconocimiento de sus ciclos evolutivos caos orden. El problema de ver es la línea de investigación del Centro de Aplicaciones de la Teoría del Caos (Bogotá, Buenos Aires. Este trabajo es un avance de la investigación “Mil Matices: materiales para una teoría de las crisis”, cuyo propósito, entre otros, plantea: ¿Cuál es, en realidad, la esencia y el origen del Caos, y cómo pueden aplicarse sus enfoques en una sociedad que necesita superar sus crisis y aprender a moverse en contextos turbulentos?

  18. In Situ Observation of MgO Inclusions in Liquid Iron-Aluminum Alloys

    Science.gov (United States)

    Mu, Haoyuan; Zhang, Tongsheng; Yang, Liang; Xavier, Rodrigo R.; Fruehan, Richard J.; Webler, Bryan A.

    2016-08-01

    This study showed that MgO inclusions can be stable in liquid iron with elevated Al and it illustrated an important role of vaporization in the evolution of inclusions. Previous studies have shown that dissolved Al reduces MgO from slags and refractories, leading to spinel (MgAl2O4) inclusions. The elevated Al content of newer steels raises the possibility that MgO inclusions can be stable. In this work, MgO inclusions were produced and observed in an Fe-Al alloy. The inclusions in the liquid alloy at 1873 K (1600 °C) were observed in situ with a Confocal Laser Scanning Microscope (CLSM). Two types of experiments were performed: one where only a metal sample was melted and the other where the sample was in contact with a liquid, MgO-saturated slag. When no slag was present, the MgO inclusions shrank and disappeared at 1873 K (1600 °C). No inclusions were observed in situ during cooling or in post-CLSM analysis. When the MgO-saturated slag was present, the inclusion sizes were essentially constant and MgO was observed on the surface of post-CLSM samples. Analysis of the results showed that MgO can be stable in 1873 K (1600 °C), but that its presence depends on the rate of removal of Mg due to vaporization and the supply of Mg due to slag/metal or refractory/metal reactions.

  19. Low-temperature atomic layer deposition of MgO thin films on Si

    Science.gov (United States)

    Vangelista, S.; Mantovan, R.; Lamperti, A.; Tallarida, G.; Kutrzeba-Kotowska, B.; Spiga, S.; Fanciulli, M.

    2013-12-01

    Magnesium oxide (MgO) films have been grown by atomic layer deposition in the wide deposition temperature window of 80-350 °C by using bis(cyclopentadienyl)magnesium and H2O precursors. MgO thin films are deposited on both HF-last Si(1 0 0) and SiO2/Si substrates at a constant growth rate of ˜0.12 nm cycle-1. The structural, morphological and chemical properties of the synthesized MgO thin films are investigated by x-ray reflectivity, grazing incidence x-ray diffraction, time-of-flight secondary ion mass spectrometry and atomic force microscopy measurements. MgO layers are characterized by sharp interface with the substrate and limited surface roughness, besides good chemical uniformity and polycrystalline structure for thickness above 7 nm. C-V measurements performed on Al/MgO/Si MOS capacitors, with MgO in the 4.6-11 nm thickness range, allow determining a dielectric constant (κ) ˜ 11. Co layers are grown by chemical vapour deposition in direct contact with MgO without vacuum-break (base pressure 10-5-10-6 Pa). The as-grown Co/MgO stacks show sharp interfaces and no elements interdiffusion among layers. C-V and I-V measurements have been conducted on Co/MgO/Si MOS capacitors. The dielectric properties of MgO are not influenced by the further process of Co deposition.

  20. Effect of MgO Additive on Volumetric Expansion of Self-Degradable Cements

    Energy Technology Data Exchange (ETDEWEB)

    Sugama T.; Warren, J.; Butcher, T.

    2011-09-30

    We identified hard-burned magnesium oxide (MgO) as a suitable expansive additive for improving the plugging performance of self-degradable, temporary sodium silicate-activated slag/Class C fly ash (SSASC) blend cement sealers into rock fractures in Enhanced Geothermal Systems (EGSs). MgO extended the volumetric expansion of sealers during their exposure to a hydrothermal environment at 200 C under pressures, ranging from 300 to 1500 psi. A great expansion ratc of 19.3% was observed by adding 3.0 wt% MgO under 300 psi pressure, thus promising to plug thoroughly inner fracture. When the pressure was increased from 300 psi to 1500 psi, the expansion rate of cement markedly reduced, corresponding to the formaLion of crack-free specimens and the improvement of compressive strength. However, with 3.0 wt% MgO, the specimens still engendered the generation of numerous visual cracks, although they were prepared under a high pressure of 1500 psi. The effective content of MgO in minimizing and eliminating the generation of cracks was 2.0 wt%, which provided a moderate expansion of {ge} 0.5%. The compressive strength of 2.0 wt% MgO specimens made under a pressure of 300 psi rose {approx} 1.7-fold to 4816 psi with an increasing pressure to 1500 psi. The in-situ growth of brucite crystal formed by the hydrothermal hydration of MgO was responsive for such an expansion of the SSASC cement; meanwhile. two crystalline hydrothermal reaction products, 1.1 nm tobermorite and calcium silicate hydrated, contributed to the development of the sealer's compressive strength. Thus, the increasing pressure seems to suppress and control a growth rate of brucite crystal in response to a lower extension of expansion. Furthermore, all MgO-conlaining SSASC sealers possessed the water-catalyzed self-degradable properties.

  1. Functionalization of mesoporous carbon with superbasic MgO nanoparticles for the efficient synthesis of sulfinamides.

    Science.gov (United States)

    Chakravarti, Rajashree; Mano, Ajayan; Iwai, Hideo; Aldeyab, Salem S; Kumar, R Pradeep; Kantam, M Lakshmi; Vinu, Ajayan

    2011-06-06

    Highly basic MgO nanoparticles with different sizes have been successfully immobilized over mesoporous carbon with different pore diameters by a simple wet-impregnation method. The prepared catalysts have been characterized by various sophisticated techniques, such as XRD, nitrogen adsorption, electron energy loss spectroscopy, high-resolution TEM, X-ray photoelectron spectroscopy, and the temperature-programmed desorption of CO(2). XRD results reveal that the mesostructure of the support is retained even after the huge loading of MgO nanoparticles inside the mesochannels of the support. It is also demonstrated that the particle size and dispersion of the MgO nanoparticles on the support can be finely controlled by the simple adjustment of the textural parameters of the supports. Among the support materials studied, mesoporous carbon with the largest pore diameter and large pore volume offered highly crystalline small-size cubic-phase MgO nanoparticles with a high dispersion. The basicity of the MgO-supported mesoporous carbons can also be controlled by simply changing the loading of the MgO and the pore diameter of the support. These materials have been employed as heterogeneous catalysts for the first time in the selective synthesis of sulfinamides. Among the catalysts investigated, the support with the large pore diameter and high loading of MgO showed the highest activity with an excellent yield of sulfinamides. The catalyst also showed much higher activity than the pristine MgO nanoparticles. The effects of the reaction parameters, including the solvents and reaction temperature, and textural parameters of the supports in the activity of the catalyst have also been demonstrated. Most importantly, the catalyst was found to be highly stable, showing excellent activity even after the third cycle of reaction.

  2. Homegardens of the Cao Lan, a Tai-Speaking Ethnic Minority in Vietnam’s Northern Mountains

    Directory of Open Access Journals (Sweden)

    Pijika Timsuksai

    2015-08-01

    Full Text Available The Cao Lan are a Tai-speaking ethnic group living in the Midlands of Northern Vietnam. Homegardens are an important component of their agroecosystem. The ecological structures of each homegarden of 17 households of the Cao Ngoi village in Tuyen Quang province were described and modal patterns identified. Most homegardens have organically shaped planting areas with indeterminate boundaries, polycentric planting patterns, and contain multiple species within the same bed or planting area. All of the gardens have multiple vegetation levels, with the largest share having 5 levels and a majority having more than 50% of their planting area covered by overlapping vegetation layers. Biodiversity is high with a total of 113 species recorded. Most plant species are used for food, but smaller numbers have ornamental, medicinal, and construction uses or are used for animal fodder, as stimulants, or for other purposes. Comparison of the modal structure of the Cao Lan homegardens with several Tai minority groups in Northeast Thailand, shows that, although the Cao Lan have been geographically isolated from other Tai groups for many centuries, their homegardens share a similar structural pattern, one commonly referred to as the tropical forest type. This structure is very different from the temperate type gardens of the Kinh in Vietnam with whom the Cao Lan share a common environment and are in frequent contact. The persistence of a common structural pattern among these related Tai ethnic groups, despite their inhabiting different environments, and having had no direct contact with each other for a very long time, suggests that culture exerts a strong influence over agroecosystem structure.

  3. Characterisation of the mgo operon in Pseudomonas syringae pv. syringae UMAF0158 that is required for mangotoxin production

    Directory of Open Access Journals (Sweden)

    Arrebola Eva

    2012-01-01

    Full Text Available Abstract Background Mangotoxin is an antimetabolite toxin that is produced by strains of Pseudomonas syringae pv. syringae; mangotoxin-producing strains are primarily isolated from mango tissues with symptoms of bacterial apical necrosis. The toxin is an oligopeptide that inhibits ornithine N-acetyl transferase (OAT, a key enzyme in the biosynthetic pathway of the essential amino acids ornithine and arginine. The involvement of a putative nonribosomal peptide synthetase gene (mgoA in mangotoxin production and virulence has been reported. Results In the present study, we performed a RT-PCR analysis, insertional inactivation mutagenesis, a promoter expression analysis and terminator localisation to study the gene cluster containing the mgoA gene. Additionally, we evaluated the importance of mgoC, mgoA and mgoD in mangotoxin production. A sequence analysis revealed an operon-like organisation. A promoter sequence was located upstream of the mgoB gene and was found to drive lacZ transcription. Two terminators were located downstream of the mgoD gene. RT-PCR experiments indicated that the four genes (mgoBCAD constitute a transcriptional unit. This operon is similar in genetic organisation to those in the three other P. syringae pathovars for which complete genomes are available (P. syringae pv. syringae B728a, P. syringae pv. tomato DC3000 and P. syringae pv. phaseolicola 1448A. Interestingly, none of these three reference strains is capable of producing mangotoxin. Additionally, extract complementation resulted in a recovery of mangotoxin production when the defective mutant was complemented with wild-type extracts. Conclusions The results of this study confirm that mgoB, mgoC, mgoA and mgoD function as a transcriptional unit and operon. While this operon is composed of four genes, only the last three are directly involved in mangotoxin production.

  4. Influence of MgO and Hybrid Fiber on the Bonding Strength between Reactive Powder Concrete and Old Concrete

    OpenAIRE

    Mo Jinchuan; Ou Zhongwen; Wang Yahui

    2016-01-01

    The reactive powder concrete (RPC) was used as concrete repair material in this paper. The influence of steel fiber, steel fiber + MgO, and steel fiber + MgO + polypropylene fiber (PPF) on the mechanical properties of RPC repair materials and the splitting tensile strength between RPC and old concrete was studied. Influences of steel fiber, MgO, and PPF on the splitting tensile strength were further examined by using scanning electronic microscopy (SEM) and drying shrinkage test. Results indi...

  5. Origin and geochemistry of Pan-African granitoid rocks in the Gabal Um Shomer area, Southwestern Sinai, Egypt

    Institute of Scientific and Technical Information of China (English)

    E1-Tokhi M.M.; Musallum A.; Amin B.M.

    2009-01-01

    Geological, petrological and geochemical studies indicated that there are two distinct types of granitoid rocks: older quartz diorites to granodiorite assemblage and younger granitoids, the latter occurring in two phases. The older granitoids have a meta-aluminous chemistry and a calc-alkaline character, with high MgO, Fe2O3, TiO2, CaO, P2O5, Sr and low SiO2, K2O, and Rb. Their major and trace elements data, together with low 87Sr/ 86Sr ratios (0.7029±0.0008) are indicative of I-type affinities. The second- and third-phase granitoids range from calc-alkaline to alkaline, respectively. The second-phase granitoids have a peraluminous chemistry and high Sr, Ba, CaO, MgO, Al2O3 and Ti2O and low SiO2, K2O, Nb, Y and Rb relative to the third-phase granitoids. The corundum normative nature and field observations suggested that it was formed by partial melting of the lower crust. The third-phase granitoids are alkaline in nature and characterized by higher SiO2, Rb, Y, Nb and lower MgO, Sr and Ba values than the younger granitoids (phase II). They are A-type granitoids which were generated from below or within the existing continental crust.

  6. DFT Study of Metal Atoms Adsorbed at Low-coordinated Sites of MgO (001) Surface

    Institute of Scientific and Technical Information of China (English)

    徐艺军; 章永凡; 陈文凯; 李俊篯

    2003-01-01

    The adsorption of metal atoms, Ni, Pd, Pt, Cu, Ag and Au, at low-coordinated edge and corner oxygen sites of MgO (001) surface has been studied theoretically by using density functional method with cluster models embedded in a large array of point charges. For comparison, the interaction of metal atoms with perfect regular oxygen site of MgO (001) surface was also calculated. As regards these metal atoms adsorbed at perfect oxygen sites of MgO (001) surface, Cu, Ag and Au are very weakly bonded to the surface of MgO; Ni, Pd and Pt, on the other hand, exhibit strong interactions with perfect oxygen sites of MgO (001) surface; the large adsorption energy shows that there exist strong bonds formed between these metal atoms with surface oxygen sites. For the metal atoms adsorbed at edge and corner sites, the adsorption energy is much increased, consistent with our previous study of CO and Cl2 adsorption on MgO (001) surface. This illustrates that the low-coordinated sites, especially corner site, are more advantageous positions for those metal atoms adsorbed on MgO (001) surface. The Mulliken population analysis indicates that the electron transferred from MgO to the metal atoms were increased with the decrease of the coordination numbers, which may be one of the reasons for changing catalytic efficiency and selectivity of the metal particles supported by MgO.

  7. First-principles calculations of perpendicular magnetic anisotropy in Fe1-x Co x /MgO(001) thin films.

    Science.gov (United States)

    Cai, Guanzhi; Wu, Zhiming; Guo, Fei; Wu, Yaping; Li, Heng; Liu, Qianwen; Fu, Mingming; Chen, Ting; Kang, Junyong

    2015-01-01

    The perpendicular magnetic anisotropy (PMA) of Fe1-x Co x thin films on MgO(001) was investigated via first-principles density-functional calculations. Four different configurations were considered based on their ground states: Fe/MgO, Fe12Co4/MgO, Fe10Co6/MgO, and Fe8Co8/MgO. As the Co composition increases, the amplitude of PMA increases first from Fe/MgO to Fe12Co4/MgO, and then decreases in Fe10Co6/MgO; finally, the magnetic anisotropy becomes horizontal in Fe8Co8/MgO. Analysis based on the second-order perturbation of the spin-orbit interaction was carried out to illustrate the contributions from Fe and Co atoms to PMA, and the differential charge density was calculated to give an intuitive comparison of 3d orbital occupancy. The enhanced PMA in Fe12Co4/MgO is ascribed to the optimized combination of occupied and unoccupied 3d states around the Fermi energy from both interface Fe and Co atoms, while the weaker PMA in Fe10Co6/MgO is mainly attributed to the modulation of the interface Co-d xy orbital around the Fermi energy. By adjusting the Co composition in Fe1-x Co x , the density of states of transitional metal atoms will be modulated to optimize PMA for future high-density memory application.

  8. Gelling preparation of starting materials for dry and wet syntheses of silicate minerals

    OpenAIRE

    Ikeda, Ko

    1985-01-01

    Gelling technique on the preparation of starting materials of silicates for both dry and wet (hydrothermal) syntheses has been fundamentally reinvestigated on the following components, SiO_2, Al_2O_3, Fe_2O_3, Cr_20_3, MgO, FeO, NiO and CaO by precipitating with excess ammonia water in ethyl alcohol solutions. On the basis of solubilities at each pH for each component, a general procedure for the preparation of starting materials including Na_2O and K_2O has been proposed.

  9. A novel approach for arsenic adsorbents regeneration using MgO.

    Science.gov (United States)

    Tresintsi, Sofia; Simeonidis, Konstantinos; Katsikini, Maria; Paloura, Eleni C; Bantsis, Georgios; Mitrakas, Manassis

    2014-01-30

    An integrated procedure for the regeneration of iron oxy-hydroxide arsenic adsorbents by granulated MgO is proposed in this study. A continuous recirculation configuration, with a NaOH solution flowing sequentially through the saturated adsorbent (leaching step) and the MgO (adsorption step) column beds, was optimized by utilizing the high arsenic adsorption efficiency of MgO at strong alkaline environments. Experimental results indicated that the total amount of leached arsenic was captured by MgO whereas the regenerated iron oxy-hydroxide recovered around 80% of its removal capacity upon reuse. The improved adsorption capacity of MgO for As(V), which is maximized at pH 10, is explained by the intermediate hydration to Mg(OH)2 and the following As(V) oxy-anions adsorption on its surface through the formation of monodentate inner sphere complexes, as it is deduced from the AsK-edge X-ray absorption fine structure (EXAFS) analysis. In addition to the economical-benefits, corresponding tests proved that the solid wastes of this process, namely spent MgO/Mg(OH)2, can be environmentally safely disposed as stable additives in cement products, while the alkaline solution is completely detoxified and can be recycled to the regeneration task.

  10. Heteroepitaxial growth of TiN film on MgO (100) by reactive magnetron sputtering.

    Science.gov (United States)

    Chen, Wei-Chun; Peng, Chun-Yen; Chang, Li

    2014-01-01

    TiN thin films were deposited on MgO (100) substrates at different substrate temperatures using rf sputtering with Ar/N2 ratio of about 10. At 700°C, the growth rate of TiN was approximately 0.05 μm/h. The structural and electrical properties of TiN thin films were characterized with x-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall measurements. For all deposition conditions, XRD results show that the TiN films can be in an epitaxy with MgO with cube-on-cube orientation relationship of (001)TiN // (001)MgO and [100]TiN // [100]MgO. TEM with selected-area electron diffraction pattern verifies the epitaxial growth of the TiN films on MgO. SEM and AFM show that the surface of the TiN film is very smooth with roughness approximately 0.26 nm. The minimum resistivity of the films can be as low as 45 μΩ cm.

  11. Influence of Light Calcining Hydration of Magnesite on MgO Sintering

    Institute of Scientific and Technical Information of China (English)

    LI Huan; YU Jingkun; KUANG Shibo

    2009-01-01

    Sintered magnesia clinker (also called sintered MgO ) was prepared with Mg(OH)2 (prepared by light calcining hydration of magnesite) and magnesite as starting materials, respectively, by the technical process : light calcining (850 ℃ 1 h )→grinding → molding →firing ( 1 600 ℃ 3 h ). The morphology and struc-ture of light calcined MgO powders prepared with mag-nesite or Mg(OH)2 were analyzed by XRD, SEM and FT-IR. The sinterability and microstructure of sintered magnesia prepared with magnesite or Mg(OH)2 were re-searched. The results showed that: (1) light calcined MgO powders prepared with magnesite or Mg (OH)2 were both face-centered cubic structure. The light cal-cined MgO prepared with magnesitehad the residual of functional group CO32- , and that prepared with Mg (OH)2 didn't have CO32-, and was easy to break, which reduced the grinding time. (2) Because of the high activity of the light calcined MgO prepared with Mg(OH)2 and the catalysis of the water residual in the decomposing process of Mg(OH)2, the apparent porosity of sintered magnesia decreased to 0.6% from 2.0% of before hydration, closed porosity decreased to 2.8% from 6.1%, and bulk density increased to 3.46 g·cm-3 from 3.29 g·cm-3

  12. Inversion of Ferromagnetic Proximity Polarization in GaAs by MgO Interlayers

    Science.gov (United States)

    Li, Y.; Chye, Y.; Chiang, Y. F.; Pi, K.; Wang, W. H.; Stephens, J. M.; Mack, S.; Awschalom, D. D.; Kawakami, R. K.

    2008-03-01

    Ferromagnet/semiconductor hybrid structures are building blocks for spin transport devices and spin-based logic gates for large- scale circuits. Recent experiments achieved success in making a lateral Fe/GaAs spin transport device, but anomalous bias dependence of the spin injection signal demand an understanding of the role of atomic-scale interfacial structure in determining the spin dependent reflection and transmission coefficients. In our studies, we incorporate a spin-filtering material MgO in the Fe/GaAs structure, and directly study the spin dependent reflection properties of the interface, or the ferromagnetic proximity polarization (FPP) effect, through ultrafast optical measurements. We find that the FPP in Fe/MgO/GaAs can be tuned by controlling MgO thickness, and we observe a sign change by MgO interlayers. Through study of the related nuclear spin polarization, we also observed sign change of FPP with laser intensity when MgO thickness is in the transition range of sign change. By modification of the interface, mainly changing oxygen partial pressure during MgO growth, we find that the Fe-Mg bond is a key factor in the sign change. Supported by CNID, ONR and NSF.

  13. Atomic layer deposition of MgO films on yttria-stabilized zirconia microtubes

    Energy Technology Data Exchange (ETDEWEB)

    Part, Marko, E-mail: markopa@ut.ee [University of Tartu, Institute of Physics, Department of Materials Science, Riia 142, EE-51014 Tartu (Estonia); Tamm, Aile; Kozlova, Jekaterina; Mändar, Hugo; Tätte, Tanel [University of Tartu, Institute of Physics, Department of Materials Science, Riia 142, EE-51014 Tartu (Estonia); Kukli, Kaupo [University of Tartu, Institute of Physics, Department of Materials Science, Riia 142, EE-51014 Tartu (Estonia); University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014, Univ. Helsinki (Finland)

    2014-02-28

    Deposition of MgO thin film on nanocrystalline yttria-stabilized zirconia microtubes was investigated. The microtubes were prepared by self-formation from threads drawn directly from zirconium butoxide [Zr(OBu){sub 4}] precursor and heat treated at 800 °C. The tubes possessed 100% tetragonal phase, their typical outer diameter was 50 μm, inner diameter 30 μm and length 1 cm. MgO films were deposited from β-diketonate-type precursor 2,2,6,6-tetramethyl-heptanedionato-3,5-magnesium(II) at 220 °C by atomic layer deposition. Thickness of MgO film on microtubes was 15.8 nm and growth rate 0.105 Å/cycle. - Highlights: • MgO films were deposited on the surface of yttria-stabilized zirconia microtubes. • The studies are carried out on the basis of surface modification of microtubes. • Films were deposited from β-diketonate-type precursor Mg(thd){sub 2}. • The growth temperature of MgO film was 220 °C.

  14. Spatial and temporal variations of water quality in Cao-E River of eastern China

    Institute of Scientific and Technical Information of China (English)

    CHEN Ding-jiang; LU Jun; YUAN Shao-feng; JIN Shu-quan; SHEN Ye-na

    2006-01-01

    Evaluation and analysis of water quality variations were performed with integrated consideration of water quality parameters, hydrological-meteorologic and anthropogenic factors in Cao-E River, Zhejiang Province of China. Cao-E River system has been polluted and the water quality of some reaches are inferior to Grade V according to National Surface Water Quality Standard of China (GB2002). However, mainly polluted indices of each tributary and mainstream are different. Total nitrogen (TN) and total phosphorus (TP) in the water are the main polluted indices for mainstream that varies from 1.52 to 45.85 mg/L and 0.02 to 4.02 mg/L,respectively. TN is the main polluted indices for Sub-watershed Ⅰ, Ⅱ, Ⅳ and Ⅴ (0.76 to 18.27 mg/L). BOD5 (0.36 to 289.5 mg/L),CODMn (0.47 to 78.86 mg/L), TN (0.74 to 31.09 mg/L) and TP (0 to 3.75 mg/L) are the main polluted indices for Sub-watershed Ⅲ.There are tow pollution types along the river including nonpoint source pollution and point source pollution types. Remarkably temporal variations with a few spatial variations occur in nonpoint pollution type reaches (including mainstream, Sub-watershed Ⅰ and Ⅱ) that mainly drained by arable field and/or dispersive rural dwelling district, and the maximum pollutant concentration appears in flooding seasons. It implied that the runoff increases the pollutant concentration of the water in the nonpoint pollution type reaches. On the other hand, remarkably spatial variations occur in the point pollution type reaches (include Sub-watershed Ⅲ, Ⅳ and Ⅴ) and the maximum pollutant concentration appears in urban reaches. The runoff always decreases the pollutant concentration of the river water in the seriously polluted reaches that drained by industrial point sewage. But for the point pollution reaches resulted from centralized town domestic sewage pipeline and from frequent shipping and digging sands, rainfall always increased the concentration of pollutant (TN) in the river water

  15. Cathodic behavior of molten CaCl2-CaO and CaCl2-NaCl-CaO

    Science.gov (United States)

    Wang, Shu-Lan; Wang, Wei; Li, Shi-Chao; Cao, Shan-Hui

    2010-12-01

    The cathodic behavior of molten CaCl2, CaCl2-CaO and equimolar CaCl2-NaCl-CaO was studied by cyclic voltammograms and constant potential polarization at temperatures of 1123 to 1173 K on molybdenum and titanium electrodes. The diffusion coefficient of Ca2+ (CaO) in molten CaCl2-CaO was calculated from the linear relationship between the square root of scan rate and the peak current density. The deposition potentials and the potential temperature coefficient of CaO in molten CaCl2-0.5mol%CaO and CaCl2-NaCl-0.5mol%CaO were also obtained from their cyclic voltammograms. The result shows that CaO is more easily reduced than CaCl2. The addition of NaCl in molten CaCl2-CaO induces the underpotential electrodeposition of CaO.

  16. Thermodynamics Behavior of Germanium During Equilibrium Reactions between FeOx-CaO-SiO2-MgO Slag and Molten Copper

    Science.gov (United States)

    Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S.; Reuter, M. A.

    2016-10-01

    The distribution ratio of germanium (Ge), L_{{Ge}}^{s/m} during equilibrium reactions between magnesia-saturated FeOx-CaO-SiO2 (FCS) slag and molten copper has been measured under oxygen partial pressures from 10-10 to 10-7 atm and at temperatures 1473 to 1623 K (1200 to 1350 °C). It was observed that the Ge distribution ratio increases with increasing oxygen partial pressure, and with decreasing temperature. It was also observed that the distribution ratio is strongly dependent on slag basicity. The distribution ratio was observed to increase with increasing optical basicity. At fixed CaO concentration in the slag, the distribution ratio was found to increase with increasing Fe/SiO2 ratio, tending to a plateau at L_{{Ge}}^{s/m} = 0.8. This behavior is consistent with the assessment of ionic bond fraction carried out in this study, and suggested the acidic nature of germanium oxide (GeO2) in the slag system studied. The characterisation results of the quenched slag suggested that Ge is present in the FeOx-CaO-SiO2-MgO slag predominantly as GeO2. At 1573 K (1300 °C) and p_{{{{O}}2 }} = 10-8 atm, the activity coefficient of GeO2 in the slag was calculated to be in the range of 0.24 to 1.50. The results from the current study suggested that less-basic slag, high operating temperature, and low oxygen partial pressure promote a low Ge distribution ratio. These conditions are desired for maximizing Ge recovery, for example, during pyrometallurgical processing of Ge-containing e-waste through secondary copper smelting. Overall, the thermodynamics data generated from this study can be used for process modeling purposes for improving recovery of Ge in primary and secondary copper smelting processes.

  17. Synthesis of MgO Nanoparticles by Solvent Mixed Spray Pyrolysis Technique for Optical Investigation

    Directory of Open Access Journals (Sweden)

    K. R. Nemade

    2014-01-01

    Full Text Available Solvent mixed spray pyrolysis technique has attracted a global interest in the synthesis of nanomaterials since reactions can be run in liquid state without further heating. Magnesium oxide (MgO is a category of the practical semiconductor metal oxides, which is extensively used as catalyst and optical material. In the present study, MgO nanoparticles were successfully synthesized using a solvent mixed spray pyrolysis. The X-ray diffraction pattern confirmed the formation of MgO phase with an excellent crystalline structure. Debye-Scherrer equation is used for the determination of particle size, which was found to be 9.2 nm. Tunneling electron microscope analysis indicated that the as-synthesized particles are nanoparticles with an average particle size of 9 nm. Meanwhile, the ultraviolet-visible spectroscopy of the resulting product was evaluated to study its optical property via measurement of the band gap energy value.

  18. Low-pressure ETEM Studies of Au assisted MgO Nanorod Growth

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Duchstein, Linus Daniel Leonhard; Ming, Lin;

    with the support and their surroundings. However, information about the crystal structure of their bulk and surface is often obtained from measurements averaged over large numbers of particles. Here, we present environmental transmission electron microscopy (ETEM) studies of the growth of MgO nanorods from Au...... catalyst nanoparticles in a controlled gas atmosphere, in order to elucidate the mobility of Au surface atoms and the configuration of the Au/MgO interface. The particles are synthesized by depositing a thin layer of Au onto MgO smoke particles. The Au agglomerates into particles that are a few nanometers...... in diameter, providing a model system for the investigation of nanoparticle surface and interface properties. Earlier studies report that MgO nanorod growth is driven by the electron beam. The growth is, however, strongly dependent on the gaseous environment in the microscope. We have studied the electron...

  19. Preparation of special silicon steel grade MgO from hydromagnesite

    Institute of Scientific and Technical Information of China (English)

    Xiangyang Zhou; Shanni Li; Jie Li; Hongzhuan Liu; Shangyuan Wu

    2007-01-01

    A preparation technology of MgO powder used in special silicon steel from hydromagnesite mineral has been developed.The preparation technology includes the following steps: (1) calcining the hydromagnesite at 700-750 ℃ for 1.5-2 h; (2) hydrating the the slurry, the carbonation temperature, CO2 pressure, and end point PH value of carbonation are less than 40℃, 0.4-0.6 MPa, and 7 respectively during the carbonation process; (4) preparing precipitated basic magnesium carbonate by thermally decomposing the Mg(HCO3)2 solution at 90-100 ℃; (5) obtaining the MgO product by calcining the precipitated basic magnesium carbonate at 850-950 ℃ for 30-60 min, and adopting flowing nitrogen during the cooling process. By using this technology, more than 80wt% magnesium in hydromagnesite mineral can be extracted, and high-performance MgO products used in special silicon steel can be obtained.

  20. Synthesis of MgO granule and its precursors via common ion effect.

    Science.gov (United States)

    Choi, Se-Bum; Lee, Dong-Kyu; Yu, Hyunung

    2012-07-01

    It is well known that the shape and size of inorganic nanostructures have much influence on their optical, electrical and physical properties. MgO is a promising material with potential applications in a variety of fields such as catalyst support, reinforcing reagent and good component in superconductors. In this study, flower-like Mg(OH)2 and cubic MgCO3 have been successfully prepared via hydrolysis control of magnesium salt and alkaline solution with common ions under hydrothermal condition by the formation of nano-platelets assembly. Subsequent calcination converts both Mg(OH)2 and MgCO3 into the corresponding MgO granules of similar flower-like and cubic morphology and size to each precursor. The physical and chemical properties of MgO and its precursors of Mg(OH)2 and MgCO3 are investigated by SEM, XRD, FT-IR, and TGA analysis.

  1. 从接受美学的维度看影视剧中曹操形象的塑造%A Survey on the Screen Image of Cao Cao from the Perspective of ReceptionAesthetics

    Institute of Scientific and Technical Information of China (English)

    齐学东

    2014-01-01

    T he flourished Chinese historical literature has helped to bring historical personages in-to literature and traditional opera .However ,being influenced by different historical background ,aes-thetic ideologies ,moral judgment and creative personalities ,the artistic image of historical images al-ways differ from its original image and it is difficult to achieve the unification of historical reality and artistic reality ,w hich puzzles the adaption of film and television programs .Cao Cao is a typical exam-ple .As there are many debates about his historical image and artistic image ,it has become a tough task to reallocate the image of Cao Cao in films and television plays .Up to now ,in China ,there are no less than one hundred Three-kingdoms-themed plays ,which have directly or indirectly related to the image of Cao Cao .Therefore ,his screen image has become rich ,marvelous and contradictory . From the perspective of reception aesthetics ,the shaping of Cao Cao’s image is the editors’ ,direc-tors’ and actors’ reception of Cao Cao’s historical image and artistic image .%中国史传文学发达,历史人物常常成为文学、戏曲等艺术描绘的对象。由于受不同时代的历史氛围、审美思想、道德评判、个性创作等因素的影响,历史人物的艺术形象很难做到历史真实与艺术真实的完美统一,往往存在或多或少的差异,这给当代影视改编带来很大困惑。尤其像曹操这样的历史人物,其历史形象和艺术形象呈现不同向度的矛盾,历来存在争议,在影视创作时,影视作者对其影视形象的定位就非常困难。《三国》题材的影视作品多达百部,大多直接或间接描写曹操这一人物,其影视形象也呈现出丰富、复杂、矛盾的面貌。从接受美学的维度看,曹操影视形象的塑造,正是影视编剧、导演、演员对其历史形象和艺术形象的接受。

  2. Mechanism of Enhancing Extraction of Vanadium from Stone Coal by Roasting with MgO

    Directory of Open Access Journals (Sweden)

    Fang Chen

    2017-02-01

    Full Text Available In this paper, the extraction of vanadium from stone coal by roasting with MgO and leaching with sulfuric acid has been investigated, and the mechanism analysis of stone coal roasting with MgO was studied. The results indicated that under the conditions that the mass fraction of the particles with grain size of 0–0.074 mm in raw ore was 75%, the roasting temperature was 500 °C, the roasting time was 1 h, MgO addition was 3 wt %, the sulfuric acid concentration was 20 vol %, the liquid-to-solid ratio was 1.5 mL/g, the leaching temperature was 95 °C, and leaching time was 2 h, resulting in a vanadium leaching efficiency of 86.63%, which increased by 7.73% compared with that of blank roasting. The mechanism analysis showed that the degree of calcite decomposition was low and, thus, magnesium vanadate was more easily formed than calcium vanadate below 500 °C. Moreover, magnesium vanadate was easier to dissolve than calcium vanadate during the sulfuric acid leaching process. Thus, the vanadium leaching efficiency was enhanced by using MgO as a roasting additive below 500 °C. Additionally, at high temperature the formation of tremolite would consume calcium oxide produced from the decomposition of calcite, thus, the formation of calcium vanadate was hindered, and V2O5 would react with MgO to form magnesium vanadate. Therefore, the vanadium leaching efficiency of roasting with MgO was higher than that of blank roasting at high temperature.

  3. Grain boundaries at the surface of consolidated MgO nanocrystals and acid-base functionality.

    Science.gov (United States)

    Vingurt, Dima; Fuks, David; Landau, Miron V; Vidruk, Roxana; Herskowitz, Moti

    2013-09-21

    The increase of the surface basicity-acidity of MgO material by factors of 1.8-3.0 due to consolidation of its nanocrystals was demonstrated by the indicator titration. It was shown that the parallel increase of surface acidity and basicity is attributed to the formation of grain boundaries (GB) after MgO aerogel densification. A simple model predicting the increase of surface acidity-basicity of MgO that correlates with the results of direct measurements was proposed. The model is based on the study of the fine atomic structure at GB surface areas in consolidated MgO nanocrystals in the framework of Density Functional Theory. It is found that the displacements of coordinatively unsaturated surface ions near the GB are significant at the distances ~3-4 atomic layers from the geometrical contact plane between nanocrystals. The detailed analysis of atomic positions inside GB demonstrated the coordination deficiency of surface atoms at the GB areas leading to the formation of stretched bonds and to creation of low coordinated surface ions due to splitting of coordination numbers of surface atoms belonging to GB areas. Density of states for electrons shows the existence of additional states in the band gap close to the bottom of the conduction band. The adsorption energy of CO2 molecules atop oxygen atoms exposed at surface GB areas is of the same order of magnitude as that reported for oxygen atoms at crystallographic edges and corners of MgO crystals. It provides additional options for bonding of molecules at the surface of nanocrystalline MgO increasing the adsorption capacity and catalytic activity.

  4. A Comparative Study of Female-Themed Literary Creations by Cao Pi and Cao Zhi%曹丕、曹植女性题材创作比较论

    Institute of Scientific and Technical Information of China (English)

    张竞怿

    2012-01-01

    As prominent representatives of Jian'an Literature,and influenced by the circumstances of that era,Cao Pi and Cao Zhi both have produced a series of outstanding literary works themed on females.However,owing to differences in personal experiences,character,and temperament,they have developed diverse artistic styles in their respective poetry creation.The exquisitely subtle mood,the masterly skills of expressing emotions,and the delicate and gentle nature of literati are the main characteristics of Cao Pi's poems.By contrast,the poems written by Cao Zhi feature gorgeous and refined diction,deep personal sentiments,and various remarkable descriptions of feelings,affections and attitudes.Their literatures can not only exhibit the spirit of the times,but also add creative and unique radiance to the literature world.%曹丕与曹植是建安文学的杰出代表,受时代风气的影响,都写出了一系列优秀的女性题材作品。但由于二人的经历、性格、气质有所不同,因此在这类诗歌创作中又形成了不同的艺术风格:曹丕的代言体诗委婉细腻,工于言情,多文士之气。曹植诗则多生情态,辞采华茂,经常寄予个人深沉的情感。他们的作品既有浓郁的时代气息,又放射出独特的个性光辉。

  5. Response of Stream Pollution Characteristics to Catchment Land Cover in Cao-E River Basin, China

    Institute of Scientific and Technical Information of China (English)

    SHEN Ye-Na; L(U) Jun; CHEN Ding-Jiang; SHI Yi-Ming

    2011-01-01

    This study addressed the relationship of river water pollution characteristics to land covers and human activities in the catchments in a complete river system named Cao-E River in eastcrn China. Based on the hydrogsochemical data collected monthly over a period of 3 years, cluster analysis (CA) and principal component analysis (PCA) were adopted to categorize the river reaches and reveal their pollution characteristics. According to the differences of water quality in the river reaches and land use patterns and average population densities in their catchments, the whole river system could be categorized into three groups of river reaches, i.e., non-point sources pollution reaches (NPSPR), urban reaches (UR) and mixed sources pollution reaches (MSPR). In UR and MSPR, the water quality was mainly impacted by nutrient and organic pollution, while in NPSPR nutrient pollution was the main cause. The nitrate was the main nitrogen form in NPSPR and particulate phosphorus was the main phosphorus form in MSPR. There were no apparent trends for the variations of pollutant concentrations with increasing river flows in NPSPR and MSPR, while in UR the pollutant concentrations decreased with increasing river flows. Thus dry season was the critical period for water pollution control in UR. Therefore, catchment land covers and human activities had significant impact on river reach water pollution type, nutrient forms and water quality responses to hydrological conditions, which might be crucial for developing strategies to combat water pollution in watershed scale.

  6. Inhibitory Effects of Daiokanzoto (Da-Huang-Gan-Cao-Tang on P-Glycoprotein

    Directory of Open Access Journals (Sweden)

    Yuka Watanabe

    2012-01-01

    Full Text Available We have studied the effects of various Kampo medicines on P-glycoprotein (P-gp, a drug transporter, in vitro. The present study focused on Daiokanzoto (Da-Huang-Gan-Cao-Tang, which shows the most potent inhibitory effects on P-gp among the 50 Kampo medicines studied, and investigated the P-gp inhibitory effects of Daiokanzoto herbal ingredients (rhubarb and licorice root and their components by an ATPase assay using human P-gp membrane. Both rhubarb and licorice root significantly inhibited ATPase activity, and the effects of rhubarb were more potent than those of licorice root. The content of rhubarb in Daiokanzoto is double that in licorice root, and the inhibition patterns of Daiokanzoto and rhubarb involve both competitive and noncompetitive inhibition, suggesting that the inhibitory effects of Daiokanzoto are mainly due to rhubarb. Concerning the components of rhubarb, concentration-dependent inhibitory effects were observed for (−-catechin gallate, (−-epicatechin gallate, and (−-epigallocatechin gallate. In conclusion, rhubarb may cause changes in the drug dispositions of P-gp substrates through the inhibition of P-gp. It appears that attention should be given to the interactions between these drugs and Kampo medicines containing rhubarb as an herbal ingredient.

  7. Preparation and characterizaton of CaO nanoparticle for biodiesel production

    Science.gov (United States)

    Gupta, Jharna; Agarwal, Madhu

    2016-04-01

    Nanoparticle of CaO from calcium Nitrate (CaO/CaN) and Snail shell (CaO/SS) are successfully synthesized by method as described in the literature and used as an active and stable catalyst for the biodiesel production. These catalysts are characterized by Fourier-transform infrared spectra (FT-IR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The average crystalline size in nanometer was also calculated by Debye-Scherrer equation. The performance of the CaO/CaN and CaO/SS were tested for their catalytic activity via transesterification process and it was found that biodiesel yield has been increased from 93 to 96%. The optimum conditions for the highest yield were 8wt% catalyst loading, 65°C temperature, 12:1 methanol/oil molar ratio, and 6 h for reaction time. The nano catalyst from snail shell exhibits excellent catalytic activity and stability for the transesterification reaction, which suggested that this catalyst would be potentially used as a solid base nano catalyst for biodiesel production. In order to examine the reusability of catalyst developed from snail shell, five transesterification reaction cycles were also performed.

  8. Ab initio structure dertermination and property characterization of high-pressure Ca-O compounds and Li2(OH)Br crystals

    Science.gov (United States)

    Higgins, Christopher A.

    Theoretical modeling and computational simulations play an important role in materials research. In this thesis, we report on the study of two material systems using various computational methods. The first material system studied here are Cax-Oy compounds under high pressure. Calcium and oxygen are amongst the most abundant elements on Earth, and they form the compound calcium oxide (CaO) that is widely used and very stable at ambient pressures. Although the crystal structure and chemical composition of CaO seems to be simple and well understood, metastable or stable Ca-O compounds with unconventional stoichiometry may exist at high pressures. In this work, first-principles density functional theory calculations and ab initio evolutionary simulations have been used to predict high pressure Ca-O structures. We show that under increasing pressure, the stability of the Ca-O system changes and new materials emerge with different stable or metastable structures. In addition to CaO, we systematically examined structures for Ca, Ca2O, Ca2O3, Ca3O, Ca 3O2, Ca7O, CaO2, CaO3, CaO 7, and O at high pressures. The high-pressure phase diagram for these compounds is determined along with the electronic density of states and stoichiometry plots. Our energetic analysis identified three new stable Ca-O compounds, namely Ca2O3 and CaO2 that are thermodynamically stable above 40 GPa, and CaO3 becomes thermodynamically stable at 150 GPa. The second material system studied in this work is the compound Li 2(OH)Br. This compound has been shown by experiment to be a promising solid electrolyte for advanced solid state ionic battery applications. However, the crystal structure of this compound is highly complex and has not been determined accurately. This has impeded its further investigation and potential applications. We modeled the structure effectively using the density functional theory via VASP software. Having successfully determined the correct structure within our model and

  9. Preparation of nanocrystalline MgO by surfactant assisted precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, Mehran, E-mail: rezaei@kashanu.ac.ir [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Khajenoori, Majid; Nematollahi, Behzad [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

    2011-10-15

    Highlights: {yields} Nanocrystalline magnesium oxide with high surface area. {yields} MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. {yields} MgO prepared with surfactant showed a plate-like shape. {yields} Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N{sub 2} adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH){sub 2} crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH){sub 2} nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time

  10. Discharge characteristics of plasma display panels with Si-doped MgO protective layers

    Energy Technology Data Exchange (ETDEWEB)

    Ram, Sanjay K., E-mail: sanjayk.ram@gmail.co [Laboratoire de Physique des Interfaces et des Couches Minces (UMR 7647 du CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex (France); Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 (India); Barik, U.K. [Samtel Color Limited, Ghaziabad-201009 (India); Sarkar, Surajit; Biswas, Paramananda [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 (India); Singh, Vandana [Laboratoire de Physique des Interfaces et des Couches Minces (UMR 7647 du CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex (France); Dwivedi, H.K. [Samtel Color Limited, Ghaziabad-201009 (India); Kumar, Satyendra [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 (India)

    2009-10-01

    We report on our study of the influence of varying concentrations of Si doping on the secondary electron emission (SEE) yield of MgO thin films prepared by electron beam evaporation technique. The series of Si-doped MgO films were microstructurally characterized with various tools like X-ray diffraction, scanning electron microscopy and atomic force microscopy. The optimization of the concentration of Si doping is seen to enhance the SEE yield. We discuss the correlation of SEE yield in the context of different deposition and measurement conditions and crystalline orientation.

  11. YBCO thin film evaporation on as-deposited silver film on MgO

    Science.gov (United States)

    Azoulay, J.

    1999-11-01

    YBa 2Cu 3O 7- δ (YBCO) thin film was evaporated on as-deposited Ag buffer layer on MgO substrate. A simple, inexpensive vacuum system equipped with one resistively heated source was used. The subsequent heat treatment was carried out under low oxygen partial pressure at a relatively low temperature and short dwelling time. The films thus obtained were characterized for electrical properties using DC four-probe electrical measurements and inspected for structural properties and chemical composition by scanning electron microscopy (SEM). It is shown that YBCO thin film can grow on as-deposited thin silver layer on MgO substrate.

  12. Uma introdução ao controle do caos em sistemas hamiltonianos quase integráveis

    OpenAIRE

    Silva Junior,Vilarbo da; Carvalho, Alexsandro M.

    2014-01-01

    Sistemas Hamiltonianos quase integráveis são de grande interesse em diversos campos de pesquisa da física e da matemática. Nesses sistemas, o espaço de fase apresenta trajetórias regulares e caóticas. Essas trajetórias dependem, em parte, da amplitude da perturbação que quebra a integrabilidade do sistema. O valor da perturbação crítica responsável por esta transição é um elemento chave no controle do caos. No presente trabalho, exploramos um procedimento para o controle do caos em sistema ha...

  13. Fabrication and performance testing of CaO insulator coatings on V-5%Cr-5%Ti in liquid lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Dragel, G. [Argonne National Lab., Chicago, IL (United States)

    1995-04-01

    Corrosion resistance of structural materials, and the magnetohydrodynamic (MHD) force and its influence on thermal hydraulics and corrosion, are major concerns in the design of liquid-metal blankets for magnetic fusion reactors (MFRs). The objective of this study is to develop in-situ stable coatings at the liquid-metal/structural-material interface, with emphasis on coatings that can be converted to an electrically insulating film to prevent adverse currents that are generated by the MHD force from passing through the structural walls. The electrical resistance of CaO coatings produced on V-5Cr-5Ti by exposure of the alloy to liquid Li that contained 0.5 - 8.5 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degree}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420{degree}C to produce a CaO coating.

  14. Pengaruh Katalis Koh Dan Cao Pada Pembuatan Biodiesel Minyak Kemiri Dengan Reaksi Transesterifikasi Menggunakan Eter Sebagai Kosolvent

    OpenAIRE

    Limbong, Juniar

    2010-01-01

    Fuel reserves are limited it is necessary to utilize alternative technologies to exploit the vegetable oil as an energy-friendly alternatives that can be processed with transesterification reaction to obtain an alternative fuel by using an alkaline catalyst such as KOH and CaO. Base catalyzed transesterification is a slow reaction and the production of esters is not the optimum metal can be used to overcome such kosolvent ether Transesterification reaction has been carried out in the media...

  15. Influence of SrO substitution for CaO on the properties of bioactive glass S53P4.

    Science.gov (United States)

    Massera, Jonathan; Hupa, Leena

    2014-03-01

    Commercial melt-quenched bioactive glasses consist of the oxides of silicon, phosphorus, calcium and sodium. Doping of the glasses with oxides of some other elements is known to affect their capability to support hydroxyapatite formation and thus bone tissue healing but also to modify their high temperature processing parameters. In the present study, the influence of gradual substitution of SrO for CaO on the properties of the bioactive glass S53P4 was studied. Thermal analysis and hot stage microscopy were utilized to measure the thermal properties of the glasses. The in vitro bioactivity and solubility was measured by immersing the glasses in simulated body fluid for 6 h to 1 week. The formation of silica rich and hydroxyapatite layers was assessed from FTIR spectra analysis and SEM images of the glass surface. Increasing substitution of SrO for CaO decreased all characteristic temperatures and led to a slightly stronger glass network. The initial glass dissolution rate increased with SrO content. Hydroxyapatite layer was formed on all glasses but on the SrO containing glasses the layer was thinner and contained also strontium. The results suggest that substituting SrO for CaO in S53P4 glass retards the bioactivity. However, substitution greater than 10 mol% allow for precipitation of a strontium substituted hydroxyapatite layer.

  16. The Software Package PAOLAC: an embedment of the analytical code PAOLA within the CAOS problem-solving environment

    Science.gov (United States)

    Carbillet, Marcel; Jolissaint, Laurent; Maire, Anne-Lise

    We present the Software Package PAOLAC (“PAOLA within Caos”) in its first distributed version. This new numerical simulation tool is an embedment of the analytical adaptive optics simulation code PAOLA (“Performance of Adaptive Optics for Large (or Little) Apertures”) within the CAOS problem-solving environment. The main goal of this new tool is to allow an easier and direct comparison between studies performed with the analytical open-loop code PAOLA and studies performed with the end-to-end closed-loop Software Package CAOS (“Code for Adaptive Optics Systems”), with the final scope of better understanding how to take advantage from the two approaches: one analytical allowing extremely quick results on a wide range of cases and the other extremely detailed but with a computational and memory costs which can be impressive. The practical implementation of this embedment is briefly described, showing how this absolutely does not affect any aspect of the original code which is simply directly called from the CAOS global graphical interface through ad hoc modules. A comparison between end-to-end modelling and analytical modelling is hence also initiated, within the specific framework of wide-field adaptive optics at Dome C, Antarctica.

  17. The decrease of carbonation efficiency of CaO along calcination-carbonation cycles: Experiments and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Bouquet, E.; Leyssens, G.; Schonnenbeck, C.; Gilot, P. [Laboratoire de Gestion des Risques et Environnement, Mulhouse (France)

    2009-05-15

    Successive calcination-carbonation cycles, using CaO as sorbent, have been performed either in a classical fixed bed reactor or using a thermogravimetric analyser. Significant differences in carbonation efficiencies were obtained, possibly due to different conditions prevailing for CaO sintering during the calcination stage. The effect of the presence of CO{sub 2} on sintering was confirmed. A simple model of the decay of the carbonation capacity along cycles based on the specific surface area of non-sintered micrograins of CaO is able to predict the decrease of the extent of conversion obtained after 40 carbonations along calcination-carbonation cycles. The asymptotic extent of conversion is obtained when all the micrograins present within a grain are sintered. A detailed model of the carbonation shows that the voids present between the micrograins are filled up by carbonate when a critical thickness of the carbonate layer around each micrograin reaches 43 nm. Then, carbonation becomes controlled by diffusion at the scale of the whole grain, with the CO{sub 2} diffusion coefficient decreasing (at 650 {sup o}C) from 2 x 10{sup -12} to 6.5 x 10{sup -14} m{sup 2}/s as carbonation proceeds from 50% conversion to 76% (first cycle). This scale change for diffusion is responsible for the drastic decrease of the carbonation rate after the voids between micrograins are filled up.

  18. Promotion Effect of CaO Modification on Mesoporous Al2O3-Supported Ni Catalysts for CO2 Methanation

    Directory of Open Access Journals (Sweden)

    Wen Yang

    2016-01-01

    Full Text Available The catalysts Ni/Al2O3 and CaO modified Ni/Al2O3 were prepared by impregnation method and applied for methanation of CO2. The catalysts were characterized by N2 adsorption/desorption, temperature-programmed reduction of H2 (H2-TPR, X-ray diffraction (XRD, and temperature-programmed desorption of CO2 and H2 (CO2-TPD and H2-TPD techniques, respectively. TPR and XRD results indicated that CaO can effectively restrain the growth of NiO nanoparticles, improve the dispersion of NiO, and weaken the interaction between NiO and Al2O3. CO2-TPD and H2-TPD results suggested that CaO can change the environment surrounding of CO2 and H2 adsorption and thus the reactants on the Ni atoms can be activated more easily. The modified Ni/Al2O3 showed better catalytic activity than pure Ni/Al2O3. Ni/CaO-Al2O3 showed high CO2 conversion especially at low temperatures compared to Ni/Al2O3, and the selectivity to CH4 was very close to 1. The high CO2 conversion over Ni/CaO-Al2O3 was mainly caused by the surface coverage by CO2-derived species on CaO-Al2O3 surface.

  19. Synergistic effect of MgO nanoparticles for electrochemical sensing, photocatalytic-dye degradation and antibacterial activity

    Science.gov (United States)

    Reddy Yadav, L. S.; Lingaraju, K.; Manjunath, K.; Raghu, G. K.; Sudheer Kumar, K. H.; Nagaraju, G.

    2017-02-01

    MgO nanoparticles (NPs) have been synthesized by a simple and eco-friendly route using watermelon juice as a novel fuel. The synthesized MgO NPs have been subjected to detailed characterization using various analytical techniques. The XRD pattern confirms the crystal structure of MgO which is composed of cubic phase of periclase. The FTIR spectrum gave another manifest for the presence of Mg–O bonding at 552 cm‑1. The surface structure, morphology and particle size have been studied using SEM and TEM which show the MgO NPs are in agglomerated form, almost spherical in shape and average size is about 30–50 nm. Finally, the multidimensional studies have been examined by subjecting MgO NPs as a catalyst for the photodegradation of methylene blue dye (one of the most commonly encountered environmental pollutants), antibacterial activities and electrochemical sensing for the detection of hydrazine at trace level concentration.

  20. Effect of MgO nanoparticles embedded into Bi-2212/Ag tapes on the microstructure and superconducting properties

    Energy Technology Data Exchange (ETDEWEB)

    Ilyushechkin, Alexander Y. [CSIRO, Pullenvale 4069, QLD (Australia); Agranovski, Igor E., E-mail: i.agranovski@griffith.edu.a [Griffith School of Engineering, Griffith University, 170 Kessels Rd, Nathan, Brisbane 4111, QLD (Australia); Altman, Igor S. [Griffith School of Engineering, Griffith University, 170 Kessels Rd, Nathan, Brisbane 4111, QLD (Australia); Institute of Advanced Machinery and Design, Seoul National University, Seoul 151-742 (Korea, Republic of); Choi, Mansoo [Institute of Advanced Machinery and Design, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2010-02-25

    Magnesium oxide nanoparticles embedded into Bi-2212/Ag tapes may significantly improve transport properties of the tapes in magnetic fields as flux pinning centres. The effect of the addition of ultra-fine MgO particles, obtained by Mg combustion, in Bi-2212/Ag tapes was investigated in order to improve critical current densities of the tapes in magnetic fields. Optimization of the MgO concentration and uniformity of the MgO particles distribution across the tapes were also investigated. Microstructure of Bi-2212 ceramic layer and J{sub c} of the tapes were enhanced with addition of MgO nanoparticles with concentrations of up to 4 wt.%. Higher MgO concentrations lead to degradation of the samples' microstructure and a corresponding decrease of absolute J{sub c} values in self-field.

  1. Micro and nano MgO particles for the improvement of fracture toughness of bone-cement interfaces.

    Science.gov (United States)

    Khandaker, Morshed; Li, Yanling; Morris, Tracy

    2013-03-15

    The objective of this study was to determine whether inclusion of magnesium oxide (MgO) in micro and nanoparticulate forms in poly methyl methacrylate (PMMA) cement has any influence on the fracture toughness of bone-cement interfaces. An interfacial fracture mechanics technique was used to compare the values of fracture toughness (KIC) among bone-PMMA, bone-PMMA with micro MgO particles and bone-PMMA with nano MgO particles interfaces. This study found that the values of KIC of bone-PMMA with micro MgO particles and bone-PMMA with nano MgO particles interfaces were significantly higher when compared to the values of KIC of the bone-PMMA interface (pMgO particles to PMMA improved the quality of bone-cement union.

  2. Relationship between catchment characteristics and forms of nitrogen in Cao-E River Basin, Eastern China

    Institute of Scientific and Technical Information of China (English)

    JIN Shuquan; LU Jun; CHEN Dingjiang; SHEN Yena; SHI Yiming

    2009-01-01

    The distribution of different nitrogen forms and their spatial and temporal variations in different pollution types of tributaries or reaches were investigated. Based on the catchments characteristics the tributaries or reaches can be classified into 4 types including headwater in mountainous areas (type I), agricultural non-point source (NPS) pollution in rural areas (type II), municipal and industrial pollution in urban areas (type III), and combined pollution in the main stream (type IV). Water samples were collected monthly from July 2003 to June 2006 in the Cao-E River basin in Zhejiang, Eastern China. The concentrations of NO3-N, NH4+-N, and total nitrogen (TN) were measured. The mean concentrations of NO3-N were in the order type IV > type II> type III > type I, whereas, NH4+-N, total organic nitrogen (TON), and TN were in the order type III > type IV > type II> type I. In headwater and rural reaches, CNO3-N was much higher than CNH4+-N. In urban reaches, TON and NH4+-N were the main forms, accounting for 54.7% and 32.1% of TN, respectively. In the whole river system, CNH4+-N decrease with increasing distance from cities, and CNO3-N increased with the increasing area of farmland in the catchments. With increased river flow, the CNO3-N increased and the CNH4+-N decreased in all types of reaches, while the variations of CTON and CTN were different. For TN, the concentration may be decreased with the increase of river flow, but the export load always increased.

  3. Nanocrystal ghosting: Extensive radiation damage in MgO induced by low-energy electrons

    Science.gov (United States)

    Frankenfield, Zackery; Kane, Kenneth; Sawyer, William H.

    2017-03-01

    We report direct evidence of extensive radiation damage in MgO nanocrystals due to intense bombardment (2 × 10 electrons/nm sec) by electrons with beam energies between 60 keV and 120 keV. Based upon a minimum intensity necessary to produce the observed damage, we present an explanation based on the Knotek-Feibelman process.

  4. Influence of MgO on structure and optical properties of alumino-lithium-phosphate glasses

    Science.gov (United States)

    Jlassi, I.; Elhouichet, H.; Ferid, M.

    2016-07-01

    MgO doped lithium alumino phosphate glasses (PLA: P2O5+Li2O+Al2O3+MgO) were prepared by melt quenching technique. Raman spectra display three significant peaks at 698, 1164 and 1383 cm-1 attributed to: symmetric stretching vibrations of the bridging oxygen (BO) in the P-O-P chains, symmetric stretching vibrations of the PO2 groups, and the asymmetric vibrations vas(PO2) of the non-bridging oxygen (NBO) atoms, respectively. Also, the density, molar volumes and ion concentration have been discussed and correlated with the structural changes within the glassy matrix. Some optical constants such as refractive index and dispersion parameters (Eo: single-oscillator energy and Ed: dispersive energy) of the glasses were determined. Finally, the values of the optical band gap for direct and indirect allowed transitions have been determined from the absorption edge studies. It is deduced that the values of Eopt increase with increasing MgO content. It was assigned to structural changes induced from the formation of non-bridging oxygen. The Urbach energy (ΔE) was found to decrease from 0.578 to 0.339 eV with increasing MgO content from 0.5 to 2 mol.

  5. Epitaxial Growth of Permalloy Thin Films on MgO Single-Crystal Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ohtake, Mitsuru; Tanaka, Takahiro; Matsubara, Katsuki; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: ohtake@futamoto.elect.chuo-u.ac.jp [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

    2011-07-06

    Permalloy (Py: Ni - 20 at. % Fe) thin films were prepared on MgO single-crystal substrates of (100), (110), and (111) orientations by molecular beam epitaxy. Py crystals consisting of fcc(100) and hcp(112-bar 0) orientations epitaxially nucleate on MgO(100) substrates. With increasing the substrate temperature, the volume ratio of fcc(100) to hcp(112-bar 0) crystal increases. The metastable hcp(112-bar 0) structure transforms into more stable fcc(110) structure with increasing the film thickness. Py(110){sub fcc} single-crystal films are obtained on MgO(110) substrates, whereas Py films epitaxially grow on MgO(111) substrates with two types of fcc(111) variants whose orientations are rotated around the film normal by 180 deg. each other. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of these fcc-Py films agree within {+-}0.4% with the values of bulk fcc-Py crystal, suggesting that the strains in the films are very small. High-resolution transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the films around the Py/MgO(100) and the Py/MgO(110) interfaces to reduce the lattice mismatches. The magnetic properties are considered to be reflecting the magnetocrystalline anisotropies of bulk fcc-Py and/or metastable hcp-Py crystals and the shape anisotropy caused by the surface undulations.

  6. Removal of azo and anthraquinone reactive dyes from industrial wastewaters using MgO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moussavi, Gholamreza, E-mail: Moussavi@modares.ac.ir [Department of Environmental Health, School of Medical Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Mahmoudi, Maryam [Department of Environmental Health, School of Medical Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2009-09-15

    In the present investigation, a porous MgO powder was synthesized and tested for the removal of dyes from aqueous solution. The size of the MgO particles was in the range of 38-44 nm, with an average specific surface area of 153.7 m{sup 2}/g. Adsorption of reactive blue 19 and reactive red 198 was conducted to model azo and anthraquinone dyes at various MgO dosages, dye concentrations, solution pHs and contact times in a batch reactor. Experimental results indicate that the prepared MgO powder can remove more than 98% of both dyes under optimum operational conditions of a dosage of 0.2 g, pH 8 and a contact time of 5 min for initial dye concentrations of 50-300 mg/L. The isotherm evaluations revealed that the Langmuir model attained better fits to the experimental equilibrium data than the Freundlich model. The maximum predicted adsorption capacities were 166.7 and 123.5 mg of dye per gram of adsorbent for RB 19 and RR 198, respectively. In addition, adsorption kinetic data followed a pseudo-second-order rate for both tested dyes.

  7. Temperature variation of higher-order elastic constants of MgO

    Indian Academy of Sciences (India)

    K M Raju; R K Srivastava; Kailash

    2007-09-01

    An effort has been made for obtaining higher-order elastic constants for MgO starting from basic parameters, viz. nearest-neighbor distance and hardness parameter using Coulomb and Börn–Mayer potentials. These are calculated in a wide temperature range (100–1000 K) and compared with available theoretical and experimental results.

  8. SO2 initiates the efficient conversion of NO2 to HONO on MgO surface.

    Science.gov (United States)

    Ma, Qingxin; Wang, Tao; Liu, Chang; He, Hong; Wang, Zhe; Wang, Weihao; Liang, Yutong

    2017-03-01

    Nitrous acid (HONO) is an important source of hydroxyl radical (OH) which determines the fate of many chemically active and climate relevant trace gases. However, the sources and the formation mechanisms of HONO remain poorly understood. In this study, the effect of SO2 on the heterogeneous reactions of NO2 on MgO as a mineral dust surrogate was investigated. The reactivity of MgO to NO2 is weak while coexisting SO2 can increase the uptake coefficients of NO2 on MgO by 2-3 orders of magnitude. The uptake coefficients of NO2 on SO2-aged MgO are independent of NO2 concentrations in the range of 20-160 ppbv and relative humidity (0-70%RH). The reaction mechanism was demonstrated to be a redox reaction between NO2 and surface sulfite. In the presence of SO2, NO2 was reduced to nitrite under dry condition which could be further converted to gas-phase HONO in humid conditions. These results suggest that the reductive effect of SO2 on the heterogeneous conversion of NO2 to HONO may have a significant contribution to the unknown sources of HONO observed in polluted areas, for example in China.

  9. Rectangular nanovoids in helium-implanted and thermally annealed MgO(100)

    NARCIS (Netherlands)

    Kooi, B.J.; Veen, A. van; Hosson, J.Th.M. De; Schut, H.; Fedorov, A.V.; Labohm, F.

    2000-01-01

    Cleaved MgO(100) single crystals were implanted with 30 keV 3He ions with doses varying from 1×10^19 to 1×10^20 m-2 and subsequently thermally annealed from 100 to 1100 °C. Transmission electron microscopy observations revealed the existence of sharply rectangular nanosize voids at a depth slightly

  10. Formation and stability of rocksalt ZnO nanocrystals in MgO

    NARCIS (Netherlands)

    Eijt, S. W. H.; de Roode, J.; Schut, H.; Kooi, B. J.; De Hosson, J. Th. M.

    2007-01-01

    Coimplantation of Zn and O ions into a single crystalline MgO and subsequent thermal annealing were applied in the synthesis of ZnO nanocrystals. Electron microscopy showed that rocksalt instead of wurtzite ZnO stabilizes for relatively large nanocrystals up to similar to 15 nm, resulting from its s

  11. Formation and stability of rocksalt ZnO nanocrystals in MgO

    NARCIS (Netherlands)

    Eijt, S.W.H.; De Roode, J.; Schut, H.; Kooi, B.J.; De Hosson, J.T.M.

    2007-01-01

    Coimplantation of Zn and O ions into a single crystalline MgO and subsequent thermal annealing were applied in the synthesis of ZnO nanocrystals. Electron microscopy showed that rocksalt instead of wurtzite ZnO stabilizes for relatively large nanocrystals up to ~15 nm, resulting from its small latti

  12. Transient Cataluminescence on Flowerlike MgO for Discrimination and Detection of Volatile Organic Compounds.

    Science.gov (United States)

    Xu, Honglin; Li, Qiuyan; Zhang, Lichun; Zeng, Binrong; Deng, Dongyan; Lv, Yi

    2016-08-16

    Methodologies for simple and rapid identification of gas compounds are needed in the fields of environmental and security. Here, a new and simple method for the discrimination of gas compounds was designed through an interesting transient cataluminescence (TRCTL) phenomenon on the highly efficient MgO materials. The flowerlike MgO with high CTL activity was controllably synthesized via a facile and time-saving aqueous precipitation route and characterized by scanning electron microscopy, powder X-ray diffractometry, high-resolution transmission electron microscopy, and N2 adsorption measurements, etc. With flowerlike MgO working as the sensing material, the newly developed CTL gas sensor exhibited highly active, ultrafast, and characteristic responses toward many analytes; the TRCTL curves thus were obtained and 10 VOCs have been successfully identified. Parallel experimental results show that the controllable synthesis of flowerlike MgO can greatly enhance the discrimination capacities for VOCs. Further, the TRCTL of CHCl3 and C2H5OC2H5 were taken as typical examples to illustrate the possible sensing mechanism, which could contribute to explaining processes of catalytic oxidations. We expect this novel TRCTL concept will be of practical importance for applications including gas detection, gas discrimination, and research of chemical kinetics processes.

  13. FeO and MgO in plagioclase of lunar anorthosites: Igneous or metamorphic?

    Science.gov (United States)

    Phinney, W. C.

    1994-01-01

    The combined evidence from terrestrial anorthosites and experimental laboratory studies strongly implies that lunar anorthosites have been subjected to high-grade metamorphic events that have erased the igneous signatures of FeO and MgO in their plagioclases. Arguments to the contrary have, to this point, been more hopeful than rigorous.

  14. On the oscillator strengths of MgO and F2

    NARCIS (Netherlands)

    Main, R.P.; Schadee, A.

    1969-01-01

    In a recent paper (R. P. Main, D. J. Carlson and R. A. DuPuis, JQSRT 7, 805 (1967)), measurements of oscillator strengths of electronic transitions in the MgO-, MgH-, and F2-molecules were reported. We point out that the results reported in that paper for F2 are almost certainly invalid, and that an

  15. Effect of gold nanorods in an MgO protective layer of AC plasma display panels.

    Science.gov (United States)

    Cho, Seok Ho; Lee, Seong Min; Kim, Woo Hyun; Choi, Kyung Cheol

    2015-04-15

    We propose a modified MgO protective layer for alternating current plasma display panels. The modified MgO protective layer of the panel tested here has a structure that incorporates silica-coated Au nanorods (NRs), leading to localized surface plasmon resonance (LSPR) in the near-infrared (IR) region. The silica-coated Au NRs were synthesized by a simple chemical method and inserted into an MgO protective layer using an air-spray method. The operating voltage of the proposed structure was decreased by 10 V. The luminance and luminous efficacy of the test panel part with the silica-coated Au NRs both increased by about 15%. According to the measured results of the IR response time, the sustain discharge time lag was reduced. In addition, by inserting the silica-coated Au NRs into the MgO protective layer, a decrease of the IR emission proceeding from the plasma discharge was acquired. Finally, we investigated the LSPR effect of the silica-coated Au NRs in a simulation with a finite-difference time domain method.

  16. Efficient activation of peroxymonosulfate by magnetic Mn-MGO for degradation of bisphenol A.

    Science.gov (United States)

    Du, Jiangkun; Bao, Jianguo; Liu, Ying; Ling, Haibo; Zheng, Han; Kim, Sang Hoon; Dionysiou, Dionysios D

    2016-12-15

    A heterogeneous manganese/magnetite/graphene oxide (Mn-MGO) hybrid catalyst was fabricated through the reduction of KMnO4 by ethylene glycol in the presence of magnetite/GO (MGO) particles. The Mn-MGO catalyst exhibited high efficacy and long-term stability in activating peroxymonosulfate (PMS) to generate sulfate radicals for the removal of bisphenol A (BPA) from water. The results of the batch experiments indicated that an increase in the catalyst dose and solution pH could enhance BPA degradation in the coupled Mn-MGO/PMS system. Regardless of the initial pH, the solution pH significantly dropped after the reaction, which was caused by catalytic PMS activation. The production of sulfate radicals and hydroxyl radicals was validated through radical quenching and electron paramagnetic resonances (EPR) tests. BPA degradation pathways were proposed on the basis of LC-MS and GC-MS analyses. Finally, a possible mechanism of catalytic PMS activation was proposed that involved electron transfer from MnO or Mn2O3 to PMS with the generation of sulfate radicals, protons and MnO2, as well as the simultaneous reduction of MnO2 by PMS.

  17. Preparation and characterization of MgO nanorods coated with SnO2.

    Science.gov (United States)

    Kim, Hyunsu; Jin, Changhyun; Kim, Hyoun Woo; Lee, Chongmu

    2012-05-01

    MgO nanorods have been grown by thermal evaporation of Mg3N2 powders on Si (100) substrates coated with gold (Au) thin films. The MgO nanorods grown on Al2O3 (0001) were 0.1-0.2 microm in diameter and up to a few tens of micrometers in length. MgO/SnO2 coaxial nanorods have also been prepared by atomic layer deposition (ALD) of SnO2 onto the nanorods. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis results indicate that the MgO-cores and the SnO2 shells of the annealed coaxial nanorods are of a single crystalline nature with cubic and orthorhombic structures, respectively. The photoluminescence (PL) spectroscopy analysis results show that SnO2 coating slightly increases the PL emission intensity of MgO nanorods. The PL emission of the SnO2-coated MgO nanorods is found to be considerably enhanced by thermal annealing and to strongly depend on the annealing atmosphere. The PL emission intensity of the MgO/SnO2 coaxial nanorods has been significantly increased by annealing in a reducing atmosphere. The origin of the PL enhancement by annealing in a reducing atmosphere is discussed on the basis of energy-dispersive X-ray spectroscopy analyses.

  18. X-ray and Electron Diffraction Study of MgO

    NARCIS (Netherlands)

    Tsirelson, V.G.; Asilov, A.S.; Abramov, Yu. A.; Belokoneva, E.L.; Kitaneh, R.; Feil, D.

    1998-01-01

    Precise X-ray and high-energy transmission electron diffraction methods were used for the study of electron density and electrostatic potential in MgO crystals. The structure amplitudes were determined and their accuracy estimated using ab initio Hartree-Fock structure amplitudes as criteria. The el

  19. Study on the influence of CaO on NH{sub 3}+NO+O{sub 2} reaction system in pre-calciner

    Energy Technology Data Exchange (ETDEWEB)

    Tang, J.S.; Song, Q.; Fu, S.L.; Wu, X.Y.; Yao, Q. [Tsinghua Univ., Beijing (China). Inst. of Thermal Engineering

    2013-07-01

    This paper studied the influence of CaO on NH{sub 3}+NO+O{sub 2} reaction system in pre-calciner. Experiments were carried out in a fixed bed reactor. Influence of CaO on NH{sub 3}+NO+O{sub 2} reaction, NH{sub 3} oxidation, NH{sub 3} decomposition and NO reduction by NH{sub 3} at O{sub 2} free condition were studied. NH{sub 3} conversion rates and product selectivities were obtained for each reaction condition. It was proved that the influence of CaO on SNCR performance changed with temperature. CaO promoted SNCR performance at 650 C and changed to inhibit SNCR performance when temperature increased above 700 C. CaO influenced the reaction of NH{sub 3}+NO+O{sub 2} mainly by catalyzing NH{sub 3} oxidation. NH{sub 3} conversion rate and NO selectivity decreased when NH{sub 3} concentration increased. Addition of NO into NH{sub 3} heterogeneous oxidation had little effect on NH{sub 3} conversion rate but decreased NO selectivity. A reaction mechanism for NH{sub 3}NO+O{sub 2} reaction on CaO surface was proposed. Heterogeneous reaction model of NH{sub 3}+NO+O{sub 2} on CaO surface was established based on the proposed reaction mechanism. Numerical results showed that the reaction model in this paper could predict NH3 oxidation and NH{sub 3}+NO+O{sub 2} reaction on CaO surface very well.

  20. 用"需求层次理论"解读曹植悲情人生%Interpretation of Cao Zhi's Tragic Life with Maslow's Hierarchy of Needs

    Institute of Scientific and Technical Information of China (English)

    赵光存

    2015-01-01

    Maslow's hierarchy of needs can be divided into five levels in the shape of pyramids. From the low to the high, they are respectively physiological needs, safety needs, love and belonging needs, esteem needs and self-actualization needs. Cao Zhi's life can be divided into two parts, i.e. the period of time before Cao Pi becomes the emperor of Wei and the period of time after that. The former part of Cao Zhi's life is full of independence and freedom, and his needs are greatly satisfied. Cao Zhi lives a happy and full life. Howev-er, in the latter part of his life, things have changed dramatically. Under the great pressure of being suspected and persecuted by Cao Pi and his son Cao Rui, Cao Zhi's needs cannot be met, which directly leads to Cao Zhi's tragic life.%马斯洛需求层次理论用金字塔的形式把人的需求分为五个层次,从低到高依次为生理需求、安全需求、爱和归属需求、尊重需求和自我实现需求.纵观曹植的一生,以建安二十五年(220年)曹丕继曹操为魏王为界,曹丕称帝前,曹植的需求能得到极大满足和实现,曹植的人生是幸福的,充实的;而曹丕称帝后,由于受到曹丕父子的猜忌和迫害,曹植的人生发生了急剧变化,需求无法得到满足和实现,这直接导致了曹植的悲情人生.

  1. SINTESIS BAHAN UBAHAN GRADUAL ALUMINUM TITANAT/KORUNDUM DARI ALUMINA TRANSISI DENGAN PENAMBAHAN MgO

    Directory of Open Access Journals (Sweden)

    Achmad Sulhan Fauzi

    2013-03-01

    Full Text Available This article describes the results of research on the use of transition alumina for improving the performance of ceramics. Synthesis has been made of gradual changes materials (Functionally Graded Materials, FGM aluminum titanate (AT / corundum based on transition alumina powders with the addition of MgO as a stabilizer of AT as much as 2 wt.%. Samples without the addition of MgO was also made for comparison. Transition alumina with and without the addition of MgO were calcined at a temperature of 1100C for 1 hour to become ?-alumina. The powder mixture was compacted at a pressure of 49.3 MPa and then prasintered at a temperature of 1100C for 1 hour, then repeatedly infiltrated with infiltrator TiCl3 solution (20% which prepared by dissolving the Ti metal powders into HCl. Furthermore, the material sintered at temperatures of 1500C with a holding time for 3 hours. Physical character of materials showed an increase in density and decrease in porosity of the material due to the addition of MgO. Phase identification results obtained from the content of AT and corundum phases which gradual in depth, indicating that FGM has been formed. These results were supported by analysis of x-ray diffraction pattern showing the formation of a solid solution Al2 (1-x + MgxTi1 xO5 which marked by the shifting of the peak of AT phase in FGM samples with the addition of MgO. Tulisan ini menjelaskan hasil penelitian tentang penggunaan alumina transisi untuk meningkatkan performa keramik. Telah dilakukan sintesis bahan ubahan gradual (Functionally Graded Material, FGM aluminum titanat (AT/korundum berbahan dasar serbuk alumina transisi dengan penambahan MgO sebagai penstabil AT sebanyak 2 wt.%. Sampel tanpa tambahan MgO juga dibuat sebagai pembanding. Alumina transisi dengan dan tanpa penambahan MgO dikalsinasi pada temperatur 1100C selama 1 jam sehingga menjadi ?-alumina. Serbuk campuran dikompaksi pada tekanan 49,3 MPa lalu diprasinter pada temperatur 1100C selama

  2. Subsurface Synthesis and Characterization of Ag Nanoparticles Embedded in MgO

    Energy Technology Data Exchange (ETDEWEB)

    Vilayur Ganapathy, Subramanian; Devaraj, Arun; Colby, Robert J.; Pandey, Archana; Varga, Tamas; Shutthanandan, V.; Manandhar, Sandeep; El-Khoury, Patrick Z.; Kayani, Asghar N.; Hess, Wayne P.; Thevuthasan, Suntharampillai

    2013-03-08

    Metal nanoparticles exhibit localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the dielectric medium surrounding it. LSPR causes field enhancement near the surface of the nanoparticle making them interesting candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix form hotspots which are prime locations for LSPR spectroscopy and sensing. This study involves synthesizing partially buried Ag nanoparticles in MgO and investigating the characteristics of this material system. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 10000C for 10 and 30 hours. A detailed optical and structural characterization was carried out to understand the evolution of Ag nanoparticle microstructure and size distribution inside the MgO matrix. Micro x-ray diffraction (MicroXRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes as seen from aberration corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

  3. Geochemistry of Sedimentation and Diagenesis in Qixia Formation (Early Permian) of Badong,Hubei Province, China: Implications for T-R Cycle Interpretation

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Combined with sedimentary observation and mineralogical research on a type of drusy celestite of early diagenesis in origin, this geochemical study on the Qixia Formation at the Shuibuya Section, Badong County, Hubei Province of south China evaluates the contribution of sedimentation and diagenesis to the mass fractions of CaO, Al2O3, MgO, SiO2, Fe2O3, Na2O, K2O, Mn, Sr, P and Ba in the carbonates. The Sr, initially released from the stabilization of carbonate calcium mineral, precipitated with sulfate ion as celestite in early diagenetic environment, where sulfate reduction was the minimum. Then it redistributed in burial diagenetic environment, where celestite was replaced by calcite. The fractions of the MgO and SiO2 in the carbonates were mainly modified by the early dolomitization and silicification respectively. That of the Na2O was overprinted by the burial diagenesis. Multivariate statistical analysis on data of sixty bulk rocks indicates that the mass fractions of the Al2O3, K2O, Fe2O3, Mn, CaO, P and Ba were affiliated with the sedimentary factor despite the obvious decrease of CaO during early dolomitization and silicification. Among them, the Al2O3 and K2O mainly represent the detrital components. In addition, a dysaerobic sedimentary background was confirmed by trace element measurement and information derived from the formation of the celestite. This genetic discrimination facilitates the interpretation of the transgressive-regressive (T-R) cycle and specialities featured this unusual carbonate unit.

  4. Reel-to-reel deposition of epitaxial double-sided MgO buffer layers for coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Yan, E-mail: xueyanuestc@126.com [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Xiong, Jie, E-mail: jiexiong@uestc.edu.cn [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang, Yahui; Zhang, Fei; Zhao, Rui-Peng [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Hui, Wang; Wang, Quiling [Applied Research Laboratory of Superconduction and New Material, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Cheng, Guo; Zhao, Xiao-Hui; Tao, Bo-Wan [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-06-15

    Highlights: • Growth of biaxially textured MgO films on flexible substrates. • Double-sided IBAD buffer template for the first time. • Studying the influence of ion energy and film thickness on the texture. • Demonstrating double-sided YBCO films with overall critical current of 300 A/cm. - Abstract: We have successfully employed a double-sided process to deposit MgO buffer layers on both sides of amorphous Y{sub 2}O{sub 3} surface for double-sided YBa{sub 2}Cu{sub 3}O{sub 7−δ} (YBCO) coated conductors (CCs) for the first time, the structure of which is of great prospect to improve the performance and cut the production cost. The biaxial textures of MgO buffer layer are noticeably affected by the ion energy and film thickness, which is demonstrated by X-ray diffraction. The best biaxial texture of double-sided MgO films shows ω-scan of (002) MgO and Φ-scan of (220) MgO yield full width at half maximum values of 4° and 7.8° for one side, respectively, as well as 3.5° and 6.7° for the other side. The subsequent double-sided YBCO films are deposited on the as-prepared MgO template with entire critical current of over 300 A/cm for both sides.

  5. Annealing effect of thermal spike in MgO thin film prepared by cathodic vacuum arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Daoyun, E-mail: zhudy@gdut.edu.cn [Experiment Teaching Department, Guangdong University of Technology, Guangzhou 510006 (China); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Zhao, Shoubai [School of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510400 (China); Zheng, Changxi; Chen, Dihu [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); He, Zhenhui, E-mail: stshzh@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2013-12-16

    MgO films were prepared by using pulsed cathodic vacuum arc deposition technique. The substrate bias voltage was in the range of −150 to −750 V. Film structure was investigated by X-ray diffraction (XRD). The annealing effect of thermal spike produced by the impacting of energetic ions was analyzed. The calculated results showed that the lifetime of a thermal spike generated by an energetic ion with the energy of 150 eV was less than one picosecond and it was sufficient to allow Mg{sup 2+} or O{sup 2-} to move one bond length to satisfy the intrinsic stress relief in the affected volume. The MgO(200) lattice spacings of the films deposited at different bias voltages were all larger than the ideal value of 2.1056 Å. As the bias amplitude increased the lattice spacing decreased, which indicated that the compressive stress in the film was partially relieved with increasing impacting ion energy. The stress relief also could be reflected from the film orientation with bias voltage. The biaxial elastic modulus for MgO(100), MgO(110) and MgO(111) planes were calculated and they were M{sub (100)} = 199 GPa, M{sub (110)} = 335 GPa and M{sub (111)} = 340 GPa, respectively. The M values indicated that the preferred orientation will be MgO(200) due to the minimum energy configuration when the lattice strain was large. It was confirmed by the XRD results in our experiments. - Highlights: • MgO thin films with preferred orientation were obtained by CVAD technique. • Annealing effect of a thermal spike in MgO film was discussed. • Lattice spacing of MgO film decreased with the increase of bias voltage. • Film preferred orientation changed from (200) to (220) as the bias voltage increased.

  6. Effect of post annealing on MgO thin film prepared on silicon(001) substrate in high oxygen pressure and high substrate temperature by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Satoru; Akiyama, Kensuke; Ito, Takeshi; Yasui, Manabu; Ozawa, Takeshi; Soga, Masayasu; Motoizumi, Yu [Kanagawa Industrial Technology Center, Kanagawa Prefectural Government, 705-1 Shimo-Imaizumi, Ebina, Kanagawa 243-0435 (Japan); Yoshimoto, Mamoru, E-mail: satoru@kanagawa-iri.go.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuda, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan)

    2011-03-15

    Epitaxial growth of MgO was verified with the relation of MgO(100) parallel to Si(100) (cubic on cubic growth) even with a large mismatch of lattice constants {approx} 22%, instead of 9% mismatch in 45{sup 0} rotation growth. MgO films prepared at higher deposition temperature showed (001) preferred orientation on Si(001) substrate. After post-annealing the MgO thin films, the pole figure of X-ray diffraction verified the epitaxial growth of cubic on cubic relation. Fe{sub 3}Si thin film was deposited on Si(001) substrate with the MgO film as buffer layer.

  7. Intermitência alfvênica gerada por caos na atmosfera solar e no vento solar

    Science.gov (United States)

    Rempel, E. L.; Chian, A. C.-L.; Macau, E. E. N.; Rosa, R. R.

    2003-08-01

    Dados medidos no vento solar rápido proveniente dos buracos coronais revelam que os plasmas no meio interplanetário são dominados por flutuações Alfvênicas, caracterizadas por uma alta correlação entre as variações do campo magnético e da velocidade do plasma. As flutuações exibem muitas características esperadas em turbulência magneto-hidrodinâmica totalmente desenvolvida, tais como intermitência e espectros contínuos. Contudo, os mecanismos responsáveis pela evolução de turbulência Alfvênica intermitente não são completamente compreendidos. Neste trabalho a teoria de caos é usada para explicar como sistemas Alfvênicos, modelados pela equação Schrödinger não-linear derivativa e pela equação Kuramoto-Sivashinsky, podem se tornar fortemente caóticos à medida em que parâmetros do plasma são variados. Pequenas perturbações no parâmetro de dissipação podem fazer com que o sistema mude bruscamente de um regime periódico, ou fracamente caótico, para um regime fortemente caótico. As séries temporais das flutuações do campo magnético nos regimes fortemente caóticos exibem comportamento intermitente, em que fases laminares ou fracamente caóticas são interrompidas por fortes estouros caóticos. É mostrado que o regime fortemente caótico é atingido quando as soluções periódicas ou fracamente caóticas globalmente estáveis interagem com soluções do sistema que são fortemente caóticas, mas globalmente instáveis. Estas soluções globalmente instáveis são conjuntos caóticos não-atrativos conhecidos como selas caóticas, e são responsáveis pelos fortes estouros nos regimes intermitentes. Selas caóticas têm sido detectadas experimentalmente em uma grande variedade de sistemas, sendo provável que elas desempenhem um papel importante na turbulência intermitente observada em plasmas espaciais.

  8. Influence of MgO containing strontium on the structure of ceramic film formed on grain oriented silicon steel surface

    OpenAIRE

    Vasconcelos Daniela C. Leite; Cesar Maria das Graças M.M.; Cunha Marco Antônio da; Vasconcelos Wander L.

    1999-01-01

    The oxide layer formed on the surface of a grain oriented silicon steel was characterized by SEM and EDS. 3% Si steel substrates were coated by two types of slurries: one formed by MgO and water and other formed by MgO, water and SrSO4. The ceramic films were evaluated by SEM, EDS and X-ray diffraction. Depth profiles of Fe, Si and Mg were obtained by GDS. The magnetic core losses (at 1.7 Tesla, 60 Hz) of the coated steel samples were evaluated as well. The use of MgO containing strontium red...

  9. Adsorption and dissociation of dinitrogen on transition metal (Ta, W and Re) doped MgO surface

    KAUST Repository

    Yadav, Manoj Kumar

    2016-06-16

    The adsorption and dissociation of dinitrogen on transition metal (Ta, W and Re) doped MgO(100) surface has been studied employing density functional theory. It is found that all these transition metals (TM) on MgO(100) surface are capable of adsorbing dinitrogen (N2), however there is no dissociative adsorption of N2 on single transition metal dopant. When two TM atoms are doped on MgO(100) surface, dissociative adsorption of dinitrogen occurs in all the three cases. Whether the dissociation is spontaneous or is it associated with activation barrier depends on the orientation of N2 molecule approaching the dopant site.

  10. Basicity for blast furnace-type slag containing B2O3 and high MgO

    Institute of Scientific and Technical Information of China (English)

    黄振奇; 蔡亚旻; 朱文非; 杨祖磐

    2003-01-01

    There is quite abundant resource of ludwigite ore in Liaoning Province of China. Content of MgO in the slag of pyrometallurgical separation of boron from iron is much higher than that in the ordinary slags. Through the equilibrium partition ratio of sulfur LS between the metal and the slag in an atmosphere of CO-N2, the acidic coefficients for B2O3 and the basic coefficients for MgO were estimated. The basic formulae were given for the blast furnace-type slag containing B2O3 and high MgO.

  11. Structural, chemical and electronic properties of the Co2MnSi(001)/MgO interface

    OpenAIRE

    Fetzer, Roman; Wüstenberg, Jan-Peter; Taira, Tomoyuki; Uemura, Tetsuya; Yamamoto, Masafumi; Aeschlimann, Martin; Cinchetti, Mirko

    2012-01-01

    The performance of advanced magnetic tunnel junctions build of ferromagnetic (FM) electrodes and MgO as insulating barrier depends decisively on the properties of the FM/insulator interface. Here, we investigate interface formation between the half-metallic compound Co2MnSi (CMS) and MgO by means of Auger electron spectroscopy, low energy electron diffraction and low energy photoemission. The studies are performed for different annealing temperatures TA and MgO layer coverages (4, 6, 10, 20 a...

  12. MODIFIKASI KATALIS CaO DENGAN SrO PADA REAKSI TRANSESTERIFIKASI MINYAK JELANTAH MENJADI BIODIESEL MENGGUNAKAN

    Directory of Open Access Journals (Sweden)

    N Widiarti

    2016-03-01

    Full Text Available Minyak jelantah merupakan salah satu jenis minyak nabati yang dapat digunakan sebagai sumber produksi biodiesel yang murah. Biodiesel dapat diperoleh melalui proses esterifikasi dengan katalis asam maupun transesterifikasi dengan menggunakan katalis homogen basa kuat. Pengolahan minyak jelantah menjadi biodiesel merupakan langkah yang tepat dan efektif untuk menurunkan harga biodiesel karena bahan baku yang murah dan memanfaatkan limbah minyak goreng yang dapat mengatasi masalah pembuangan minyak dan kesehatan masyarakat. Pada penelitian ini dilakukan reaksi transesterifikasi dari minyak jelantah menjadi biodiesel menggunakan katalis CaO dan SrO. Tujuan penelitian ini adalah untuk mengetahui karakteristik katalis dan aktivitas katalitiknya pada reaksi transesterifikasi minyak jelantah. Modifikasi katalis dilakukan dengan metode impregnasi SrNO3 pada katalis CaO. Katalis digunakan pada reaksi transesterifikasi minyak jelantah dengan variasi energi  (input daya 80 dan 100 watt, variasi waktu (30, 60, 90, 120 dan 150 detik dan variasi jumlah SrO/CaO (1%, 2%, 4%, 8% dan 16% b/b sebagai katalis. Karakterisasi katalis dilakukan dengan XRD dan FTIR. Hasil analisis XRD menunjukkan bahwa katalis SrO/CaO bersifat kristalin dan mempunyai karakteristik pola difraksi gabungan CaO dan SrO. Reaksi transesterifikasi optimal terjadi dengan aktivitas katalis terbaik pada energi  100 watt, waktu reaksi 120 detik dan jumlah katalis SrO/CaO sebesar 4% b/b dengan produk reaksi metil ester sebesar 92,86%. Wasted cooking oil is one type of vegetable oil that can be used as an inexpensive source of biodiesel production. Biodiesel can be obtained through esterification process with acid catalyst or transesterification using homogeneous catalyst of strong bases. Processing of wasted cooking oil into biodiesel is an appropriate and effective measures to reduce the high price of biodiesel because of cheap raw materials and it can overcome the problem of oil disposal and

  13. Calcium adsorption on MgO(100): energetics, structure, and role of defects.

    Science.gov (United States)

    Zhu, Junfa; Farmer, Jason A; Ruzycki, Nancy; Xu, Lijun; Campbell, Charles T; Henkelman, Graeme

    2008-02-20

    The adsorption of Ca on the MgO(100) surface at 300 K has been studied using microcalorimetry, in combination with LEED, AES, ISS, work function, sticking probability measurements, and density functional theory (DFT) calculations. The MgO(100) thin films (approximately 4 nm thick) were grown epitaxially on a 1 microm thick Mo(100) single-crystal. The sticking probability of Ca on MgO(100) at 300 K is unity. On the basis of AES and ISS measurements, it was determined that Ca grows mainly as 3D particles on the MgO(100) surface with a density of approximately 1 x 10(12) islands/cm2. Ca adsorbs initially at defect sites with a very high heat of adsorption (approximately 410 kJ/mol). DFT calculations attribute this high initial heat to Ca binding to kink sites (376 kJ/mol), step sites (205 kJ/mol), and lower concentrations of stronger binding sites. The heat of adsorption decreases rapidly with coverage, reaching a minimum of 162 kJ/mol at approximately 0.3 ML, where Ca is mainly adding to small 3D Ca clusters. Afterward, it increases to the value of bulk Ca heat of sublimation (178 kJ/mol) at approximately 1.2 ML, attributed to the increase in stability with increasing Ca particle size. A 1.0 eV decrease of the work function with Ca coverage from 0 to 0.3 ML indicates that Ca adsorbed at defects is cationic, in agreement with calculations showing that Ca donates electron density to the MgO. Light ion sputtering of the MgO(100) surface generates point defects, but these do not change the heat of adsorption versus coverage, implying that they do not nucleate Ca particles. Oxygen vacancies are a likely candidate; DFT calculations show that F and F+ center vacancies bind Ca more weakly than terrace sites. More extensive sputtering creates extended defects (such as steps and kinks) that adsorb Ca with heats of adsorption up to approximately 400 kJ/mol, similar to that at the intrinsic defect sites.

  14. On the use of ocean-atmosphere-wave models during an extreme CAO event: the importance of being coupled

    Science.gov (United States)

    Carniel, Sandro; Barbariol, Francesco; Benetazzo, Alvise; Bonaldo, Davide; Falcieri, Francesco M.; Miglietta, Mario M.; Ricchi, Antonio; Sclavo, Mauro

    2015-04-01

    During winter 2012 an extreme meteorological event stroke the whole Europe and particularly its central-southern sector. A strong and persistent spit of cold air coming from Siberian region (a Cold Air Outbreak, CAO) insisted on northern Italy and the Adriatic sea basin, leading to decreases in the sea temperatures up to 6 °C in less than two weeks, ice formation on the Venice lagoon and an exceptional snow fall in the Apennine region. In the sea the CAO was associated to a significant episode of dense water formation (DWF), a crucial phenomenon that heavily impacts the whole Adriatic Sea (from the sinking of water masses and associated ventilation of the northernmost shelf, to the flow along the western coast, until the flushing of southern Adriatic open slope and submarine canyons, with associated sediment transport and bottom reshaping). The extent of the DWF event in the Northern Adriatic sub-basin was estimated by means of coastal observatories, ad hoc measurements and, until now, results from existing one-way coupled atmosphere-ocean models. These are characterized by no SST feedback from the ocean to the atmosphere, and therefore by turbulent heat fluxes that may heavily reflect a non-consistent ocean state. The study proposes an investigation of the 2012 CAO using a fully coupled, three components, ocean-atmosphere-wave system (COAWST). Results highlight that, although the energy interplays between air and sea do not seem to significantly impact the wind forecasts, when providing heat fluxes that are consistent with the ocean temperature we find modified heat fluxes and air sea temperatures figures. Moreover, the consistent description of thermal exchanges adopted in the fully coupled model can affect the basin circulation, the quantification of dense water produced mass, and the description of its migration pathways and rates of off-shelf descent.

  15. Enhanced Ce{sup 3+} photoluminescence by Li{sup +} co-doping in CaO phosphor and its use in blue-pumped white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Zhendong, E-mail: haozd@ciomp.ac.cn; Zhang, Xia; Luo, Yongshi; Zhang, Ligong; Zhao, Haifeng; Zhang, Jiahua, E-mail: zhangjh@ciomp.ac.cn

    2013-08-15

    In this paper, we demonstrate a method to improve the photoluminescence of CaO: Ce{sup 3+} phosphor and delineate its first use in blue-pumped white LEDs. The results show that the yellow emission of Ce{sup 3+} is enhanced by a factor of 1.88 by adding Li{sup +} into CaO host at 474 nm blue light excitation. On analyzing the diffuse reflection spectra and fluorescence decay curves, we reveal that the photoluminescence enhancement is originated from the rise of absorbance to the excitation photons but not from the improvement of the luminescent efficiency. Li{sup +}-improved CaO: Ce{sup 3+} exhibits more red component when it is compared with the commercial Y{sub 3}Al{sub 5}O{sub 12}: Ce{sup 3+} (YAG: Ce{sup 3+}) phosphor, indicating its potential application for high color rendering white LEDs. Thus, a white LED is fabricated by combining blue InGaN LED chip with CaO: Ce{sup 3+}, Li{sup +} phosphor and a warm white light with high color rendering index (R{sub a}) of 80, low correlated color temperature (T{sub c}) of 4524 K, and sufficient luminous efficiency of 50 lm W{sup −1} is obtained. -- Highlights: • The photoluminescence of Ce{sup 3+} in CaO host was enhanced by Li{sup +} co-doping. • A CaO: Ce{sup 3+}, Li{sup +} based white LED was fabricated for the first time. • An efficient warm white light was obtained. • CaO: Ce{sup 3+}, Li{sup +} is expected to be used as a yellow phosphor for blue-pumped white LEDs.

  16. O estatuto político da amizade: A Alma do Osso, de Cao Guimarães

    Directory of Open Access Journals (Sweden)

    Rafael de Almeida

    2013-06-01

    Full Text Available A partir do conceito de amizade proposto por Giorgio Agamben, este ensaio reflete, em uma interface entre estética e política, acerca das relações de poder presentes em A Alma do Osso (Cao Guimarães, 2004. O maior relevo é dado ao modo que o cineasta partilha, por meio do filme, sua existência com o ermitão Dominguinhos da Pedra, bem como as reverberações que isso garante à forma do documentário.

  17. Design of a Novel Fluidized Bed Reactor To Enhance Sorbent Performance in CO2 Capture Systems Using CaO

    OpenAIRE

    Diego de Paz, María Elena; Arias Rozada, Borja; Grasa, Gemma; Abanades García, Juan Carlos

    2014-01-01

    This work deals with the modeling and design of a novel bubbling fluidized bed reactor that aims to improve the CO2 carrying capacity of CaO particles in CO2 capture systems by calcium looping (CaL). Inside the new reactor (the recarbonator) the particles that arrive from the carbonator of the CaL system react with a concentrated stream of CO2, thereby increasing their carbonate content up to a certain value, which can be predicted by means of the model proposed. The recarbonator model presen...

  18. Oxygen-induced shape changes of Pt nanoparticles on MgO(100)

    Energy Technology Data Exchange (ETDEWEB)

    Hejral, Uta; Stierle, Andreas; Vlad, Alina; Delheusy, Melissa; Dosch, Helmut [Max-Planck-Institut fuer Metallforschung, Heisenbergstr. 3, 70569 Stuttgart (Germany)

    2010-07-01

    Platinum nanoparticles on oxide carrier materials are used in heterogenous catalysis and are applied successfully in reactions like the oxidation of hydrocarbons or carbon monoxide. In order to achieve better catalyst efficiency, lifetime and selectivity it is important to comprehend catalytic processes on an atomic basis. Thus, the interplay between particle shape, adsorbed oxygen, bulk oxides and catalytic activity needs to be understood. Therefore Pt nanoparticles have been grown epitaxially on MgO(100) substrates under controlled conditions. It has previously been reported that Rh nanoparticles undergo reversible shape changes induced by surface oxides. We have studied oxygen-induced shape changes of Pt nanoparticles on MgO(100) by means of in situ X-ray diffraction. The experiment was performed at 300 C and oxygen pressures ranging from UHV to 500 mbar. The experimental results are compared to theoretically predicted ones.

  19. Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO.

    Science.gov (United States)

    Baumann, S; Donati, F; Stepanow, S; Rusponi, S; Paul, W; Gangopadhyay, S; Rau, I G; Pacchioni, G E; Gragnaniello, L; Pivetta, M; Dreiser, J; Piamonteze, C; Lutz, C P; Macfarlane, R M; Jones, B A; Gambardella, P; Heinrich, A J; Brune, H

    2015-12-04

    We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0±0.3  meV/atom. This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.

  20. Morphology, surface topography and optical studies on electron beam evaporated MgO thin films

    Indian Academy of Sciences (India)

    A Chowdhury; J Kumar

    2006-10-01

    Electron beam evaporated thin films of MgO powder synthesized by burning of magnesium ribbon in air and sol–gel technique are studied for their microstructure (SEM), surface topography (AFM), and optical transmission behaviour (UV-visible spectroscopy). MgO thin films are shown to be either continuous or have mesh like morphology. The bar regions are believed to be of magnesium hydroxide formed due to absorption of moisture. Their AFM images exhibit columnar/pyramidal/truncated cone structure, providing support to the 3D Stranski–Krastanov model for film growth. Further, they are shown to have high transmittance (∼90%) in the wavelength range 400–600 nm, but absorb radiation below 350 nm substantially giving signature of a band transition.

  1. Influence of MgO doping in hot-pressing tricalcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Acchar, W; Costa, A C S [Department of Physics, Federal University of Rio Grande do Norte, Natal-RN, Brazil, CEP:59072-97 (Brazil); Cairo, C A A, E-mail: acchar@dfte.ufrn.br [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos - SP (Brazil)

    2011-10-29

    Tricalcium phosphate ceramics (TCP) has been widely investigated. The main advantage of this bioceramic is its bioresorbable behavior. The factor that still limits the application of these materials as temporary implants is the low strength resistance of the TCP sintered material. The tricalcium phosphate presents an allotropic transformation {beta} to {alpha} phase around 1250 deg. C that degrades its resistance, limiting the sintering temperature of the compacted samples. The objective of this work is to study the physical and mechanical properties of hot-pressed tricalcium phosphate with MgO additions. The results obtained have shown that the hot-pressed process increases significantly the mechanical properties of TCP materials. The addition of MgO has not improved the sintering process and the properties of hot-pressed tricalcium phosphate.

  2. Influence of adsorbed fluids on the rolling contact deformation of MgO single crystals

    Science.gov (United States)

    Dufrane, K. F.

    1977-01-01

    Basic phenomena associated with rolling contact deformation were studied using MgO as a model bearing material. A hardened steel ball was rolled on MgO single crystals in slow-speed reciprocating motion and in high-speed circular motion. The resulting deformation was studied by dislocation etch-pit techniques. The presence of adsorbed fluids, such as silicone oil, white mineral oil, and toluene, with slow-speed sliding caused a dramatic change in slip mode and premature surface spalling compared with similar experiments in air or under water. In contrast, dimethyl formamide inhibited these slip processes. The results are consistent with the dependence of dislocation mobility on adsorbed species. High-speed hydrodynamic rolling with mineral oil lubrication produced a different slip phenomena entirely from the slow-speed rolling. The slip bands resembled those produced in tensile tests, and all slip apparently initiated at subsurface sites.

  3. A comparative study of equations of state for MgO

    Science.gov (United States)

    Kushwah, S. S.; Shanker, J.

    1998-10-01

    The pressure-volume-temperature relationship, isothermal bulk modulus KT and pressure derivative of KT have been evaluated for MgO in the temperature range 300-2000 K and down to a compression of V/ V0=0.60 using six different phenomenological forms for the isothermal equation of state (EOS). The results are discussed and compared with the values for MgO obtained by Isaak et al. using the potential induced breathing electron gas model based on the first principles approach. It is found that phenomenological isothermal equations are applicable even at a high temperature if the input parameters ( K0 and K0‧) corresponding to that temperature are used. The results obtained from the Vinet EOS and the Shanker EOS are very similar and also close to the ab initio values determined by Isaak et al.

  4. Processing-thermal conductivity relationships in MGO-pyrochlore composite inert matrix materials

    Science.gov (United States)

    Yates, Samantha J.

    2009-12-01

    Inert matrix (IM) materials are proposed to act as non-fertile matrices to burn excess plutonium and minor actinides in nuclear reactors. MgO is a good IM candidate because of its high thermal conductivity, good radiation resistance, and high temperature stability, but its hot water corrosion resistance is poor limiting its use in light water reactors. A composite approach has been suggested to improve the hydration resistance of the MgO by adding a pyrochlore phase to act as a hydration barrier while maximizing the effective thermal conductivity of the composite. In this work, MgO-Nd 2Zr2O7 composites are fabricated using four different processing methods to deliberately vary the microstructure thus enabling the investigation of processing-microstructure-thermal conductivity relationships in the composites. The first processing-microstructure-property relationship that is developed is the effect of the composite processing method on the sample-to-sample variation in the thermal diffusivity. The processing method affects the formation of agglomerates in the mixed composite powders, and these agglomerates are the source of MgO and Nd2Zr2O7 heterogeneities in the sintered composites. Differential sintering occurs in some of the agglomerates, resulting in the formation of circumferential cracks between the heterogeneity and the matrix. The presence of the circumferential cracks cause sample-to-sample variations of up to +/- 2 Wm-1K-1 in the thermal conductivity between composites fabricated from the same batch of mixed composite powder. This variation makes it more difficult to accurately and reliably predict the thermal conductivity of the composites. The second processing-microstructure-property relationship developed describes the effect of the contiguity of the MgO on the average thermal conductivity of the composites. The processing method is found to affect the contiguity of the MgO in the composites. Lower MgO contiguity values cause the average thermal

  5. Process for growing a film epitaxially upon a MGO surface and structures formed with the process

    Science.gov (United States)

    McKee, Rodney Allen; Walker, Frederick Joseph

    1998-01-01

    A process and structure wherein optical quality perovskites, such as BaTiO.sub.3 or SrTiO.sub.3, are grown upon a single crystal MgO substrate involves the epitaxial build up of alternating planes of TiO.sub.2 and metal oxide wherein the first plane grown upon the MgO substrate is a plane of TiO.sub.2. The layering sequence involved in the film build up reduces problems which would otherwise result from the interfacial electrostatics at the first atomic layers, and these oxides can be stabilized as commensurate thin films at a unit cell thickness or grown with high crystal quality to thicknesses of 0.5-0.7 .mu.m for optical device applications.

  6. Process for growing a film epitaxially upon a MgO surface

    Science.gov (United States)

    McKee, Rodney Allen; Walker, Frederick Joseph

    1997-01-01

    A process and structure wherein optical quality perovskites, such as BaTiO.sub.3 or SrTiO.sub.3, are grown upon a single crystal MgO substrate involves the epitaxial build up of alternating planes of TiO.sub.2 and metal oxide wherein the first plane grown upon the MgO substrate is a plane of TiO.sub.2. The layering sequence involved in the film build up reduces problems which would otherwise result from the interfacial electrostatics at the first atomic layers, and these oxides can be stabilized as commensurate thin films at a unit cell thickness or grown with high crystal quality to thicknesses of 0.5-0.7 .mu.m for optical device applications.

  7. Optical and magnetic properties of nitrogen ion implanted MgO single crystal

    Institute of Scientific and Technical Information of China (English)

    Liu Chun-Ming; Gu Hai-Quan; Xiang Xia; Zhang Yan; Jiang Yong; Chen Meng; Zu Xiao-Tao

    2011-01-01

    The microstructure, optical property and magnetism of nitrogen ion implanted single MgO crystals are studied.A parallel investigation is also performed in an iron ion implanted single MgO sample as a reference. Large structural,optical and magnetic differences are obtained between the nitrogen and iron implanted samples. Room temperature ferromagnetism with a fairly large coercivity field of 300 Oe (1 Oe=79.5775 A/m), a remanence of 38% and a slightly changed optical absorption is obtained in the sample implanted using nitrogen with a dose of 1×1018 ions/cm2. Transition metal contamination and defects induced magnetism can be excluded when compared with those of the iron ion implanted sample, and the nitrogen doping is considered to be the main origin of ferromagnetism.

  8. Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO

    Science.gov (United States)

    Baumann, S.; Donati, F.; Stepanow, S.; Rusponi, S.; Paul, W.; Gangopadhyay, S.; Rau, I. G.; Pacchioni, G. E.; Gragnaniello, L.; Pivetta, M.; Dreiser, J.; Piamonteze, C.; Lutz, C. P.; Macfarlane, R. M.; Jones, B. A.; Gambardella, P.; Heinrich, A. J.; Brune, H.

    2015-12-01

    We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0 ±0.3 meV /atom . This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.

  9. A comparison study of Co and Cu doped MgO diluted magnetic thin films

    Science.gov (United States)

    Sarıtaş, S.; ćakıcı, T.; Muǧlu, G. Merhan; Kundakcı, M.; Yıldırım, M.

    2017-02-01

    Transition metal-doped MgO diluted magnetic thin films are appropriate candidates for spintronic applications and designing magnetic devices and sensors. Therefore, MgO:Co and MgO:Cu films were deposited on glass substrates by Chemical Spray Pyrolysis (CSP) method different thin film deposition parameters. Deposited different transition metal doped MgO thin films were compared in terms of optic and structural properties. Comparison optic analysis of the films was investigated spectral absorption and transmittance measurements by UV-Vis double beam spectrophotometer technique. Comparison structural analysis of the thin films was examined by using XRD, Raman Analysis, SEM, EDX and AFM techniques. The transition metal-doped; MgO:Co and MgO:Cu thin films maybe have potential applications in spintronics and magnetic data storage.

  10. Influence of MgO containing strontium on the structure of ceramic film formed on grain oriented silicon steel surface

    Directory of Open Access Journals (Sweden)

    Vasconcelos Daniela C. Leite

    1999-01-01

    Full Text Available The oxide layer formed on the surface of a grain oriented silicon steel was characterized by SEM and EDS. 3% Si steel substrates were coated by two types of slurries: one formed by MgO and water and other formed by MgO, water and SrSO4. The ceramic films were evaluated by SEM, EDS and X-ray diffraction. Depth profiles of Fe, Si and Mg were obtained by GDS. The magnetic core losses (at 1.7 Tesla, 60 Hz of the coated steel samples were evaluated as well. The use of MgO containing strontium reduced the volume fraction of forsterite particles beneath the outermost ceramic layer. It was observed a reduced magnetic core loss with the use of the slurry with MgO containing strontium.

  11. First-principles investigation of magnetocrystalline anisotropy at the L 21 full Heusler |MgO interfaces and tunnel junctions

    Science.gov (United States)

    Vadapoo, Rajasekarakumar; Hallal, Ali; Yang, Hongxin; Chshiev, Mairbek

    2016-09-01

    Magnetocrystalline anisotropy at Heusler alloy |MgO interfaces has been studied using first-principles calculations. It has been found that Co-terminated Co2FeAl |MgO interfaces show perpendicular magnetic anisotropy up to 1.31 mJ/m2, while those with FeAl termination exhibit in-plane magnetic anisotropy. Atomic layer-resolved analysis indicates that the origin of perpendicular magnetic anisotropy in Co2FeAl |MgO interfaces can be attributed to the out-of-plane orbital contributions of interfacial Co atoms. At the same time, Co2MnGe and Co2MnSi interfaced with MgO tend to favor in-plane magnetic anisotropy for all terminations.

  12. A comparative study of the number and mass of fine particles emitted with diesel fuel and marine gas oil (MGO)

    Science.gov (United States)

    Nabi, Md. Nurun; Brown, Richard J.; Ristovski, Zoran; Hustad, Johan Einar

    2012-09-01

    The current investigation reports on diesel particulate matter emissions, with special interest in fine particles from the combustion of two base fuels. The base fuels selected were diesel fuel and marine gas oil (MGO). The experiments were conducted with a four-stroke, six-cylinder, direct injection diesel engine. The results showed that the fine particle number emissions measured by both SMPS and ELPI were higher with MGO compared to diesel fuel. It was observed that the fine particle number emissions with the two base fuels were quantitatively different but qualitatively similar. The gravimetric (mass basis) measurement also showed higher total particulate matter (TPM) emissions with the MGO. The smoke emissions, which were part of TPM, were also higher for the MGO. No significant changes in the mass flow rate of fuel and the brake-specific fuel consumption (BSFC) were observed between the two base fuels.

  13. Study on Aldol Condensation of HCHO and CH3CHO over MgO Catalysts Modified by Lanthanum and Cerium

    Institute of Scientific and Technical Information of China (English)

    王幸宜; 李春香; 杨菊群

    2004-01-01

    Aldol condensation of HCHO and CH3CHO over MgO, modified MgO and Al2O3 with rare earth oxides, was studied. The measurement of adsorption of pyrrole on catalysts by in-situ FT-IR and NH3 TPD indicated that the addition of elements La or Ce into MgO increased the acidity of the solid. In-situ FT-IR showed that the activation of-C=O in HCHO adsorbed on CeO-MgO and La2O3-MgO occurred. The measurement of catalytic activity implied that the modified catalysts can promote the formation of pentaerythritol, dipentaerthritol and tripentaerythritol.

  14. Large-area thin self-supporting carbon foils with MgO coatings

    Science.gov (United States)

    Stolarz, Anna; Maier-Komor, Peter

    2002-03-01

    Large area self-supporting carbon foils in the thickness of range of 8-22 μg/cm 2, coated with approximately 4 μg/cm 2 MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm 2. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  15. Single-Crystal Elasticity of MgO at High Pressure and Temperature

    Science.gov (United States)

    Fan, D.; Mao, Z.; Lin, J. F.; Yang, J.; Prakapenka, V.

    2014-12-01

    Periclase (MgO) is a material of key importance to Earth sciences: it is one of the most abundant minerals in Earth's lower mantle. It has the simple NaCl structure with no phase transition at least up to 200 GPa and also has very high melting temperatures above 3000 K. These wide stability ranges of MgO cover high-pressure and high-temperature conditions corresponding to the Earth's lower mantle. Therefore, precise knowledge of the thermal elastic properties of MgO, major end-members of constituent mineral phases of the lower mantle, under high pressure and high temperature condition is crucial for constructing the accurate mineralogical model of the Earth's lower mantle. Here we have measured the single-crystal elasticity of MgO using in situ Brillouin spectroscopy and X-ray diffraction at simultaneous high pressure-temperature conditions up to 33 GPa and 900 K in an externally-heated diamond anvil cell. Using the third-order Eulerian finite-strain equations to model the elasticity data, we have derived the aggregate adiabatic bulk, KS0, and shear moduli, G0, at ambient conditions: KS0=162.9 (6) GPa (the value in parentheses represents propagated uncertainties) and G0=130.7 (8) GPa, respectively, consistent with literature results. The pressure derivatives of the bulk and shear moduli at 300K are (∂KS/∂P)T=4.06 (22) and (∂G/∂P)T=2.75(±0.18), respectively, which are also consistent with previous literature results. We also derived the temperature derivatives of these moduli at constant pressure. Our results here provide accurate insights into seismic profiles and mineralogical models of the lower mantle region.

  16. Thermodynamic properties of MgO, Be, and W: a simplified computational approach

    CERN Document Server

    Wang, Y; Johansson, B

    2002-01-01

    The recently developed classical mean-field potential (MFP) approach was employed to calculate the Helmholtz free energy for periclase (MgO), the Hugoniot equation of state for beryllium (Be) at pressures up to 2000 GPa, and the families of isentropic curves for tungsten (W). The excellent agreement between the theory and the experiment further demonstrated the high accuracy and applicability of the MFP approach.

  17. The phase diagram and transport properties of MgO from theory and experiment

    Science.gov (United States)

    Shulenburger, Luke

    2013-06-01

    Planetary structure and the formation of terrestrial planets have received tremendous interest due to the discovery of so called super-earth exoplanets. MgO is a major constituent of Earth's mantle, the rocky cores of gas giants and is a likely component of the interiors of many of these exoplanets. The high pressure - high temperature behavior of MgO directly affects equation of state models for planetary structure and formation. In this work, we examine MgO under extreme conditions using experimental and theoretical methods to determine its phase diagram and transport properties. Using plate impact experiments on Sandia's Z facility the solid-solid phase transition from B1 to B2 is clearly determined. The melting transition, on the other hand, is subtle, involving little to no signal in us-up space. Theoretical work utilizing density functional theory (DFT) provides a complementary picture of the phase diagram. The solid-solid phase transition is identified through a series of quasi-harmonic phonon calculations and thermodynamic integration, while the melt boundary is found using phase coexistence calculations. One issue of particular import is the calculation of reflectivity along the Hugoniot and the influence of the ionic structure on the transport properties. Particular care is necessary because of the underestimation of the band gap and attendant overestimation of transport properties due to the use of semi-local density functional theory. We will explore the impact of this theoretical challenge and its potential solutions in this talk. The integrated use of DFT simulations and high-accuracy shock experiments together provide a comprehensive understanding of MgO under extreme conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. Modelling the chemistry of Mn-doped MgO for bulk and (100) surfaces.

    Science.gov (United States)

    Logsdail, Andrew J; Downing, Christopher A; Keal, Thomas W; Sherwood, Paul; Sokol, Alexey A; Catlow, C Richard A

    2016-10-19

    We have investigated the energetic properties of Mn-doped MgO bulk and (100) surfaces using a QM/MM embedding computational method, calculating the formation energy for doped systems, as well as for surface defects, and the subsequent effect on chemical reactivity. Low-concentration Mn doping is endothermic for isovalent species in the bulk but exothermic for higher oxidation states under p-type conditions, and compensated by electrons going to the Fermi level rather than cation vacancies. The highest occupied dopant Mn 3d states are positioned in the MgO band gap, about 4.2 eV below the vacuum level. Surface Mn-doping is more favourable than subsurface doping, and marginally exothermic on a (100) surface at high O2 pressures. For both types of isovalent Mn-doped (100) surfaces, the formation energy for catalytically important oxygen defects is less than for pristine MgO, with F(0) and F(2+)-centres favoured in n- and p-type conditions, respectively. In addition, F(+)-centres are stabilised by favourable exchange coupling between the Mn 3d states and the vacancy-localised electrons, as verified through calculation of the vertical ionisation potential. The adsorption of CO2 on to the pristine and defective (100) surface is used as a probe of chemical reactivity, with isovalent subsurface Mn dopants mildly affecting reactivity, whereas isovalent surface-positioned Mn strongly alters the chemical interactions between the substrate and adsorbate. The differing chemical reactivity, when compared to pristine MgO, justifies further detailed investigations for more varied oxidation states and dopant species.

  19. Fabrication and performance of a tubular ceria based oxygen transport membrane on a low cost MgO support

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Søgaard, Martin; Clemens, F.;

    2015-01-01

    A 30 μm thin-film tubular CGO (Ce0.9Gd0.1O1.95−δ) membrane with catalytic layers on both sides has been prepared by dip-coating on a low cost, porous magnesium oxide (MgO) support. The MgO support was fabricated through a thermoplastic extrusion process. Support, thin membrane and catalytic layers...

  20. Enhanced field emission from ZnO nanowire arrays utilizing MgO buffer between seed layer and silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Si [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Chen, Jiangtao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Mid. Road, Lanzhou 730000 (China); Liu, Jianlin [Quantum Structures Laboratory, Department of Electrical and Computer Engineering, University of California, Riverside, CA 92521 (United States); Qi, Jing, E-mail: qijing@lzu.edu.cn [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang, Yuhua, E-mail: wyh@lzu.edu.cn [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2016-11-30

    Highlights: • We obtained ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer. • FE properties of ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer is better than that without MgO buffer. • With MgO buffer, the ZnO seed layer shows lower top-bottom resistance and better electron transport. • The enhanced field emission properties can be attributed to good electron transport in seed layer, good nanowire alignment because of MgO buffer. - Abstract: Field emitters based on ZnO nanowires and other nanomaterials are promising high-brightness electron sources for field emission display, microscopy and other applications. The performance of a ZnO nanowire field emitter is linked to the quality, conductivity and alignment of the nanowires on a substrate, therefore requiring ways to improve these parameters. Here, ZnO nanowire arrays were grown on ZnO seed layer on silicon substrate with MgO buffer between the seed layer and Si. The turn-on field and enhancement factor of these nanowire arrays are 3.79 V/μm and 3754, respectively. These properties are improved greatly compared to those of ZnO nanowire arrays grown on ZnO seed layer without MgO buffer, which are 5.06 V/μm and 1697, respectively. The enhanced field emission properties can be attributed to better electron transport in seed layer, and better nanowire alignment because of MgO buffer.

  1. Unusual dissociative adsorption of H2 over stoichiometric MgO thin film supported on molybdenum

    CERN Document Server

    Song, Zhenjun

    2015-01-01

    The dissociation of a hydrogen molecule on MgO(001) films deposited on Mo(001) surface is investigated systematically using periodic density-functional theory method. The unusual adsorption behavior of heterolytic dissociative hydrogen molecule at neighboring surface oxygen and surface magnesium, is clarified here. To my knowledge, this heterolytic dissociative state has never been found before on bulk MgO(001) or metal supported MgO(001) surfaces. The results confirm that, in all cases, the heterolytic dissociation is much more favorable that homolytic dissociation both energetically and kinetically. The energy difference between two dissociative states are very large, in the range of 1.1 eV ~ 1.5 eV for Mo supported 1 ML ~ 3 ML oxide films, which inhibits, to a great extent, the homolytic dissociation in the respect of reaction thermodynamics. The energy barrier of heterolytic dissociation are about 0.5 eV, much lower that the barrier of homolytic dissociation. The transformation reaction on thick films wil...

  2. Effect of pressure on the thermal expansion of MgO up to 200 Gpa

    Institute of Scientific and Technical Information of China (English)

    Sun Xiao-Wei; Liu Zi-Jiang; Chen Qi-Feng; Song Ting; Wang Cheng-Wei

    2009-01-01

    Constant temperature and pressure molecular dynamics (MD) simulations are performed to investigate the thermal expansivity of MgO at high pressure, by using effective pair-wise potentials which consist of Coulomb, dispersion, and repulsion interactions that include polarization effects through the shell model (SM). In order to take into account non-central forces in crystals, the breathing shell model (BSM) is also introduced into the MD simulation. We present a comparison between the volume thermal expansion coefficient α dependences of pressure P at 300 and 2000 K that are obtained from the SM and BSM potentials and those derived from other experimental and theoretical methods in the case of MgO. Compared with the results obtained by using the SM potentials, the MD results obtained by using BSM potentials are more compressible. In an extended pressure and temperature range, the α value is also predicted. The properties of MgO in a pressure range of 0-200 GPa at temperatures up to 3500 K axe summarized.

  3. Effect of Electrochemically Deposited MgO Coating on Printable Perovskite Solar Cell Performance

    Directory of Open Access Journals (Sweden)

    T.A. Nirmal Peiris

    2017-02-01

    Full Text Available Herein, we studied the effect of MgO coating thickness on the performance of printable perovskite solar cells (PSCs by varying the electrodeposition time of Mg(OH2 on the fluorine-doped tin oxide (FTO/TiO2 electrode. Electrodeposited Mg(OH2 in the electrode was confirmed by energy dispersive X-ray (EDX analysis and scanning electron microscopic (SEM images. The performance of printable PSC structures on different deposition times of Mg(OH2 was evaluated on the basis of their photocurrent density-voltage characteristics. The overall results confirmed that the insulating MgO coating has an adverse effect on the photovoltaic performance of the solid state printable PSCs. However, a marginal improvement in the device efficiency was obtained for the device made with the 30 s electrodeposited TiO2 electrode. We believe that this undesirable effect on the photovoltaic performance of the printable PSCs is due to the higher coverage of TiO2 by the insulating MgO layer attained by the electrodeposition technique.

  4. A study of the dissociative recombination of CaO+ with electrons: Implications for Ca chemistry in the upper atmosphere

    Science.gov (United States)

    Bones, D. L.; Gerding, M.; Höffner, J.; Martín, Juan Carlos Gómez; Plane, J. M. C.

    2016-12-01

    The dissociative recombination of CaO+ ions with electrons has been studied in a flowing afterglow reactor. CaO+ was generated by the pulsed laser ablation of a Ca target, followed by entrainment in an Ar+ ion/electron plasma. A kinetic model describing the gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data, yielding a rate coefficient of (3.0 ± 1.0) × 10-7 cm3 molecule-1 s-1 at 295 K. This result has two atmospheric implications. First, the surprising observation that the Ca+/Fe+ ratio is 8 times larger than Ca/Fe between 90 and 100 km in the atmosphere can now be explained quantitatively by the known ion-molecule chemistry of these two metals. Second, the rate of neutralization of Ca+ ions in a descending sporadic E layer is fast enough to explain the often explosive growth of sporadic neutral Ca layers.

  5. CaO insulator and Be intermetallic coatings on V-base alloys for liquid-lithium fusion blanket applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, Chicago, IL (United States)

    1996-04-01

    The objective of this study is to develop (a) stable CaO insulator coatings at the Liquid-Li/structural-material interface, with emphasis on electrically insulating coating that prevent adverse MHD-generated currents from passing through the V-alloy wall, and (b) stable Be-V intermetallic coating for first-wall components that face the plasma. Electrically insulating and corrosion-resistant coatings are required at the liquid-Li/structural interface in fusion first-wall/blanket application. The electrical resistance of CaO coatings produced on oxygen-enriched surface layers of V-5%Cr-5%Ti by exposing the alloy to liquid Li that contained 0.5-85 wt% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. Crack-free Be{sub 2}V intermetallic coatings were also produced by exposing V-alloys to liquid Li that contained Be as a solute. These techniques can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coatings are formed by liquid-phase reactions.

  6. Fabrication, property characterization and toushening mechanism of HA-ZrO2(CaO)/316L fibre composite biomaterials

    Institute of Scientific and Technical Information of China (English)

    ZOU JianPeng; HE ZeQiang; ZHOU ZhongCheng; HUANG BaiYun; CHEN QiYuan; RUAN JianMing

    2008-01-01

    HA-ZrO2(CaO)/316L fibre composites were successfully fabricated with vacuum sintering method and their properties and toughening mechanism were studied.The results showed that HA-ZrO2(CaO)/316L fibre biocomposite having 20 vol% fibres had optimal comprehensive properties with bending strength,Young's modulus,fracture toughness and relative density equal to 140.1 MPa,117.8 GPa,5.81 MPa.m1/2and 87.1%,respectively.The research also addressed that different volume ratios of the composites led to different metallographic microstructures,and that metallographic morphologies change regularly with volume ratios of the composites.316L fibres were distributed randomly and evenly in the composites and the integration circumstance of the two phases was very well since there were no obvious flaws or pores in the composites.Two toughening mechanisms in-cluding ZrO2 phase transformation toughening mechanism and fibre pulling-out toughening mechanism existed in the compsites with the latter being the main toughening mechanism.

  7. La teoría d el caos... Esa nube turbulenta que da qué pensar

    Directory of Open Access Journals (Sweden)

    Ruben Antonio Sánchez G.

    1999-10-01

    Full Text Available "Ver las cosas hasta el fondo...¿Y si las cosas no tuvieran fondo?iAh, que bella la superficie!Quizá la superficie sea la esenciaY lo que excede la superficie sea lo que excede a todoY lo que excede a todo no es nada./Oh rostro del mundo, sólo tu, de todos los rostros,Eres la propia alma que reflejas/”PESSOA, Fernando, Poemas inconjuntos 65.(En: Poesías completas de Alberto Caeiro. Valencia: Pre-textos, 1997, p.3 19.Este texto plantea algunos de los problemas suscitados por la teoría del caos.Es decir, pretende mostrar algunas de las cuestiones que han surgido a partir de la formulación de un modo de obtención de conocimiento que parece tener ventajas sobre otros y según algunos de sus difusores, constituye una revolución en la práctica y el saber científicos. En consecuencia, presentaremos a continuación un panorama de estos problemas 01 tanto que, por una parte, nos muestran las posibilidades y los límites de dicha teoría y , por otra, nos indican en qué sentido la teoría del caos puede dar qué pensar.

  8. Relevance of the Physicochemical Properties of Calcined Quail Eggshell (CaO as a Catalyst for Biodiesel Production

    Directory of Open Access Journals (Sweden)

    Leandro Marques Correia

    2017-01-01

    Full Text Available The CaO solid derived from natural quail eggshell was calcined and employed as catalyst to produce biodiesel via transesterification of sunflower oil. The natural quail eggshell was calcined at 900°C for 3 h, in order to modify the calcium carbonate present in its structure in CaO, the activity phase of the catalyst. Both precursor and catalyst were characterized using Hammett indicators method, X-ray fluorescence (XRF, X-ray diffraction (XRD, thermogravimetric analysis (TG/DTG, CO2 temperature-programmed desorption (CO2-TPD, X-ray photoelectronic spectroscopy (XPS, Fourier infrared spectroscopy (FTIR, scanning electron microscopy (SEM, N2 adsorption-desorption at −196°C, and distribution particle size. The maximum biodiesel production was of 99.00 ± 0.02 wt.% obtained in the following transesterification reaction conditions: XMR (sunflower oil/methanol molar ratio of 1 : 10.5 mol : mol, XCAT (catalyst loading of 2 wt.%, XTIME (reaction time of 2 h, stirring rate of 1000 rpm, and temperature of 60°C.

  9. Generation of hydrogen from polyvinyl chloride by milling and heating with CaO and Ni(OH)2.

    Science.gov (United States)

    Tongamp, William; Zhang, Qiwu; Shoko, Miyagi; Saito, Fumio

    2009-08-15

    This work discusses an alternative process option for the treatment of polyvinyl chloride (PVC) by producing hydrogen (H(2)) gas, at the same time fixing chlorine for proper environmental control. In the first-stage, a milling operation is performed in a planetary ball mill to obtain a mixture of PVC sample with CaO and Ni(OH)(2) to be used as feed in the second-step, involving heating of the milled product. Analyses by thermogravimetry-mass spectroscopy (TG-MS) and gas chromatography (GC) showed H(2), CH(4), CO and CO(2) as main constituents. The results clearly show that addition of Ni(OH)(2) to provide nickel as catalyst and CaO as adsorbent to fix CO(2) and HCl gases generated during heating, assisted in clean H(2) generation with concentration near 90% at temperatures between 450 and 550 degrees C. Analyses of solids after heating by X-ray diffraction and TG-DTA techniques showed both CaOHCl and CaCO(3) as main phases in the product. This process could be developed to treat PVC wastes together with other polymers and/or plastic wastes for production of H(2) gas.

  10. Utilization of desulfurization gypsum to producing SO{sub 2} and CaO in multi-stage fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Zhu; Wang, Tao; Yang, Hairui; Zhang, Hai; Zhang, Zuyi [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering

    2013-07-01

    With emission control becomes more and more stringent, flue gas desulphurization (FGD) is commonly employed for desulfurization. However, the product of FGD, gypsum, causes the unexpected environmental problems. How to utilize the byproduct of FGD effectively and economically is a challenging task. This paper proposed the new technical process to produce SO{sub 2} and CaO by reducing the gypsum in multi-stage fluidized bed reactor with different atmosphere. In addition, some preliminary experiments were carried out in PTGA. The results show that CO concentration has little effect on the initial decomposing temperature, but affect the decomposing rate of phosphogypsum obviously. The decomposing product composed of CaS and CaO simultaneously. The ratio of the two products was determined by CO concentration. Lower CO content benefits to produce more CO product and more SO{sub 2}. The decomposition reaction of phosphogypsum in reducing atmosphere is parallel competition reaction. Therefore, it is necessary to eliminate the effect of CaS and other byproduct efficiently by the new technology, which utilize multi-atmosphere in multistage fluidized bed reactors.

  11. Reel-to-reel deposition of epitaxial double-sided MgO buffer layers for coated conductors

    Science.gov (United States)

    Xue, Yan; Xiong, Jie; Zhang, Yahui; Zhang, Fei; Zhao, Rui-Peng; Hui, Wang; Wang, Quiling; Cheng, Guo; Zhao, Xiao-Hui; Tao, Bo-Wan

    2016-06-01

    We have successfully employed a double-sided process to deposit MgO buffer layers on both sides of amorphous Y2O3 surface for double-sided YBa2Cu3O7-δ (YBCO) coated conductors (CCs) for the first time, the structure of which is of great prospect to improve the performance and cut the production cost. The biaxial textures of MgO buffer layer are noticeably affected by the ion energy and film thickness, which is demonstrated by X-ray diffraction. The best biaxial texture of double-sided MgO films shows ω-scan of (002) MgO and Φ-scan of (220) MgO yield full width at half maximum values of 4° and 7.8° for one side, respectively, as well as 3.5° and 6.7° for the other side. The subsequent double-sided YBCO films are deposited on the as-prepared MgO template with entire critical current of over 300 A/cm for both sides.

  12. Enhancement of electric-field-induced change of magnetic anisotropy by interface engineering of MgO magnetic tunnel junctions

    Science.gov (United States)

    Bonaedy, Taufik; Choi, Jun Woo; Jang, Chaun; Min, Byoung-Chul; Chang, Joonyeon

    2015-06-01

    Electric-field-induced modification of magnetic anisotropy is studied using tunnel magnetoresistance of the Co40Fe40B20/ MgO/ Co40Fe40B20 and Co40Fe40B20/ Hf (0.08 nm)/ MgO/ Co40Fe40B20 magnetic tunnel junctions. In both systems, the interfacial perpendicular magnetic anisotropy is increased with increasing electron density at the MgO interface. A quantitative comparison between the two systems reveals that the change of magnetic anisotropy energy with electric field is significantly enhanced in Co40Fe40B20/ Hf/ MgO/ Co40Fe40B20 compared to Co40Fe40B20/ MgO/ Co40Fe40B20. The sub-monolayer Hf insertion at the Co40Fe40B20/MgO interface turns out to be critical to the enhanced electric field control of the magnetic anisotropy, indicating the interface sensitive nature of the effect.

  13. Structural, electronic, magnetic and chemical properties of B-, C- and N-doped MgO(001) surfaces.

    Science.gov (United States)

    Pašti, Igor A; Skorodumova, Natalia V

    2016-01-07

    Doping of simple oxide materials can give rise to new exciting physical and chemical properties and open new perspectives for a variety of possible applications. Here we use density functional theory calculations to investigate the B-, C- and N-doped MgO(001) surfaces. We have found that the investigated dopants induce magnetization of the system amounting to 3, 2 and 1 μB for B, C and N, respectively. The dopants are found to be in the X(2-) state and tend to segregate to the surface. These impurity sites also present the centers of altered chemical reactivity. We probe the chemisorption properties of the doped MgO(001) surfaces with the CO molecule and atomic O. The adsorption of CO is much stronger on B- and C-doped MgO(001) compared to pure MgO(001) as the impurity sites serve as potent electron donors. The situation is similar to the case of atomic oxygen, for which we find the adsorption energy of -8.78 eV on B-doped MgO(001). The surface reactivity changes locally around the dopant atom, which is mainly restricted to its first coordination shell. The presented results suggest doped MgO as a versatile multifunctional material with possible use as an adsorbent or a catalyst.

  14. Solid state interactions in the systems CaO(CaCO3-Fe2O3 and CuFe2O4-CaO

    Directory of Open Access Journals (Sweden)

    Boyanov B.S.

    2005-01-01

    Full Text Available The solid state interactions in the systems CaO(CaCO3-Fe2O3 and CuFe2O4-CaO have been studied using X-ray diffraction analysis. The influence of the temperature on the ferrite formation process has been investigated in the range of 900-1200 oC and duration up to 360 min. It has been shown that a mixture of ferrites forms at 1000 oC and interaction of 240 min. The exchange reactions in the systems CuFe2O4-CaO and Cu0.5Zn0.5Fe2O4-CaO have been studied, too. It has been established that Ca2+ ions exchange Cu2+ and Zn2 partially and the solubility of copper and zinc in a 7 % sulfuric acid solution increases 10-15 times.

  15. 面子观与曹植的郁郁而终%Integration of Face View and Cao Zhi’s Bleak Destination

    Institute of Scientific and Technical Information of China (English)

    赵光存

    2014-01-01

    曹植在曹丕称帝前,个人的积极面子和消极面子都能得到极大的维护和保证;而曹丕称帝后及曹叡执政期间,曹植个人的积极面子得到的是虚伪的维护和认可,而个人的消极面子则受到极大的冒犯和侵害。智慧无法施展、政治抱负无法实现、对于真爱的追求被极端地压抑、知己被铲除,如此等等,使曹植备受煎熬,产生极大的性格分裂,找不到身份的认同感和归属感,最终导致郁郁而终。%Before Cao Pi became emperor of Kingdom Wei, Cao Zhi’s positive face and negative face could be maintained and guaranteed. However, after Cao Pi’s getting on the throne and during the reign of Cao Rui, Cao Zhi’s positive face was maintained and recognized hypocritically, and his negative face was offend-ed and violated terribly. His wisdom could not be utilized and his political pursuit failed to be realized, mean-while his right of pursuing genuine love was extremely suppressed and his close friends were killed or ex-pelled, all of which made Cao Zhi tortured. His personality was split and he had no sense of identity and be-longing, which led to his bleak destination.

  16. Um estudo sobre aplicações da teoria do caos e complexidade à gestão das cadeias de suprimentos

    OpenAIRE

    Rodolfo Leandro de Faria Olivo

    2010-01-01

    Este estudo aborda a aplicação da teoria do caos e complexidade à gestão das cadeias de suprimentos. Seu objetivo consiste em responder a questão orientadora da pesquisa, se a teoria do caos e complexidade pode enriquecer o entendimento e compreensão da gestão das cadeias de suprimentos. A fim de contextualizar essa discussão, este trabalho procurou resgatar alguns dos principais autores e conceitos do processo de mudança da visão do determinismo clássico científico do século XIX para as nova...

  17. Experimental and DFT studies of gold nanoparticles supported on MgO(111) nano-sheets and their catalytic activity.

    Science.gov (United States)

    Li, Zhi; Ciobanu, Cristian V; Hu, Juncheng; Palomares-Báez, Juan-Pedro; Rodríguez-López, José-Luis; Richards, Ryan

    2011-02-21

    A wet chemical preparation of MgO with the (111) facet as the primary surface has recently been reported and with alternating layers of oxygen anions and magnesium cations, this material shows unique chemical and physical properties. The potential to utilize the MgO(111) surface for the immobilization of metal particles is intriguing because the surface itself offers a very different environment for the metal particle with an all oxygen interface, as opposed to the typical (100) facet that possesses alternating oxygen anion and magnesium cation sites on the surface. Gold nanoparticles have demonstrated a broad range of interesting catalytic properties, but are often susceptible to aggregation at high temperatures and are very sensitive to substrate effects. Here, we investigate gold-supported on MgO(111) nanosheets as a catalyst system for the aerobic oxidation of benzyl alcohol. Gold nanoparticles deposited on MgO(111) show an increased level of activity in the solvent-free benzyl alcohol aerobic oxidation as compared to gold nanoparticles deposited on a typical MgO aerogel. TEM studies reveal that the gold nanoparticles have a hemispherical shape while sitting on the main surface of MgO(111) nanosheets, with a large Au-MgO interface. Given that the gold nanoparticles deposited on the two types of MgO have similar size, and that the two types of unmodified MgO show almost the same activities in the blank reaction, we infer that the high activity of Au/MgO(111) is due to the properties of the (111) support and/or those of the gold-support interface. To understand the binding of Au on low-index MgO surfaces and the charge distribution at the surface of the support, we have performed density functional theory (DFT) calculations on all low-index MgO substrates (with and without gold), using a model Au(10) cluster. Due to similar lattice constants of Au(111) and MgO(111) planes, the Au cluster retains its structural integrity and binds strongly on MgO(111) with either

  18. Elucidating the mechanism of Cr(VI) formation upon the interaction with metal oxides during coal oxy-fuel combustion.

    Science.gov (United States)

    Chen, Juan; Jiao, Facun; Zhang, Lian; Yao, Hong; Ninomiya, Yoshihiko

    2013-10-15

    The thermodynamics underpinning the interaction of Cr-bearing species with basic metal oxides, i.e. K2O, Fe2O3, MgO and CaO, during the air and oxy-fuel combustion of coal have been examined. The synchrotron-based X-ray adsorption near-edge spectroscopy (XANES) was used for Cr speciation. For the oxides tested, Cr(VI) formation is dominated by the reduction potential of the metals. The oxides of Ca(2+) with high reduction potential favored the oxidation of Cr(III), same for K(+). The other two basic metals, Fe2O3 and MgO with lower reduction potentials reacted with Cr(III) to form the corresponding chromites at the temperatures above 600°C. Coal combustion experiments in drop-tube furnace have confirmed the rapid capture of Cr vapors, either trivalent or hexavalent, by CaO into solid ash. The existence of HCl in flue gas favored the vaporization of Cr as CrO2Cl2, which was in turn captured by CaO into chromate. Both Fe2O3 and MgO exhibited less capability on scavenging the Cr(VI) vapor. Particularly, MgO alone exhibited a low capability for capturing the vaporized Cr(III) vapors. However, its co-existence with CaO in the furnace inhibited the Cr(VI) formation. This is beneficial for minimizing the toxicity of Cr in the coal combustion-derived fly ash.

  19. Hydrogen-rich gas production via CaO sorption-enhanced steam gasification of rice husk: a modelling study.

    Science.gov (United States)

    Beheshti, Sayyed Mohsen; Ghassemi, Hojat; Shahsavan-Markadeh, Rasoul; Fremaux, Sylvain

    2015-01-01

    Gasification is a thermochemical process in which solid or liquid fuels are transformed into synthesis gas through partial oxidation. In this paper, a kinetic model of rice husk gasification has been developed, which is interesting for the applications of the syngas produced. It is a zero-dimensional, steady-state model based on global reaction kinetic, empirical correlation of pyrolysis and is capable of predicting hydrogen yield in the presence of sorbent CaO. The model can also be used as a useful tool to investigate the influence of process parameters including steam/biomass ratio, CaO/fuel ratio (CaO/Fuel), and gasification temperature on hydrogen efficiency, CO2 capture ratio (CCR), and average carbonation conversion (Save). Similar to hydrogen formation, CCR also increases with increasing CaO/Fuel, but an opposite trend is exhibited in Save. Model predictions were compared with available data from the literature, which showed fairly good agreement.

  20. Strain induced phenomena in Ca(OH)/sub 2/ made by reaction of CaO with water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Beruto, D.; Searcy, A.W.; Barco, L.; Belleri, G.

    1980-01-01

    Three physically distinguishable, poorly crystalline forms of Ca(OH)/sub 2/ which are made by reactions of water vapor at 25/sup 0/C with CaO powders evolve heat and develop sharper x-ray diffraction patterns when heated to 300/sup 0/C. Measurements of x-ray diffraction peak line breadths, surface areas, porosities, and pore size distributions were made before and after heat treatment. The exothermic process of the one of these forms of Ca(OH)/sub 2/ which is nonporous is recrystallization of the highly strained solid to essentially unstrained crystals. The exothermic process in two porous forms of Ca(OH)/sub 2/, not only reduces their internal strains, but also reduces their surface areas and porosities.

  1. Transesterification of linoleic and oleic sunflower oils to biodiesel using CaO as a solid base catalyst

    Directory of Open Access Journals (Sweden)

    Predojević Zlatica

    2012-01-01

    Full Text Available The purpose of this work is to characterize biodiesel (i.e. methyl esters, MEs produced from linoleic and oleic sunflower oils (LSO and OSO, respectively by alkali transesterification with methanol and CaO as a heterogeneous catalyst under different reaction parameters. The parameters investigated were the methanol/oil molar ratio (4.5:1, 6:1, 7.5:1, 9:1 and 12:1 and the mass ratio of CaO to oil (2% and 3%. The physical and chemical properties of the feedstocks and MEs, like density at 15oC, kinematic viscosity at 40oC, acid value, iodine value, saponification value, cetane index, fatty acid (methyl ester composition, were determined in order to investigate the effects of LSO and OSO properties and reaction parameters on the product characteristics, yields and purity. The properties of feedstock had decisive effect on the physical and chemical properties of MEs as majority of them did not differ significantly under studied reaction conditions. The MEs produced generally met the criteria required for commercial biodiesel; in fact, the only exception was in the case of iodine value of ME produced from LSO. The product yields only slightly changed with the applied conditions; the highest yield (99.22% was obtained for ME-LSO produced at 6 mol% methanol to oil ratio, while the lowest one (93.20% was for ME-OSO produced under the lowest methanol/oil molar ratio (4.5:1. The applied catalyst amounts had similar influence on the oil conversion to biodiesel. The yields of ME-LSOs were in general somewhat higher than those obtained for ME-OSOs under the same conditions, which was attributed to the influence of the respective feedstocks' acid value and viscosity.

  2. The electronic structure of MgO nanotubes. An ab initio quantum mechanical investigation.

    Science.gov (United States)

    El-Kelany, Khaled E; Ferrabone, Matteo; Rérat, Michel; Carbonnière, Philippe; Zicovich-Wilson, Claudio M; Dovesi, Roberto

    2013-08-28

    The structural, vibrational and response properties of the (n,0) and (m,m) MgO nanotubes are computed by using a Gaussian type basis set, a hybrid functional (B3LYP) and the CRYSTAL09 code. Tubes in the range 6 ≤ n ≤ 140 and 3 ≤ m ≤ 70 were considered, being n = 2 × m the number of MgO units in the unit cell (so, the maximum number of atoms is 280). Tubes are built by rolling up the fully relaxed 2-D conventional cell (2 MgO units, with oxygen atoms protruding from the Mg plane alternately up and down by 0.38 Å). The relative stability of the (n,0) with respect to the (m,m) family, the relaxation energy and equilibrium geometry, the band gap, the IR vibrational frequencies and intensities, and the electronic and ionic contributions to the polarizability are reported. All these properties are shown to converge smoothly to the monolayer values. Absence of negative vibrational frequencies confirms that the tubes have a stable structure. The parallel component of the polarizability α(∥) converges very rapidly to the monolayer value, whereas α(⊥) is still changing at n = 140; however, when extrapolated to very large n values, it coincides with the monolayer value to within 1%. The electronic contribution to α is in all cases (α(∥) and α(⊥); 6 ≤ n ≤ 140) smaller than the vibrational contribution by about a factor of three, at variance with respect to more covalent tubes such as the BN ones, for which the ratio between the two contributions is reversed.

  3. Mechanisms of absorption and desorption of CO2 by molten NaNO3-promoted MgO.

    Science.gov (United States)

    Jo, Seung-Ik; An, Young-In; Kim, Kang-Yeong; Choi, Seo-Yeong; Kwak, Jin-Su; Oh, Kyung-Ryul; Kwon, Young-Uk

    2017-02-22

    In order to realize carbon capture and sequestration (CCS), a technology proposed to circumvent the global warming problem while maintaining the present level of economic activity, the development of efficient carbon-capturing agents is of prime importance. In addition to the prevailing amine-based agents that operate at temperatures lower than 200 °C, agents that can operate at higher temperatures are being considered to reduce the cost of CCS. For the mid-temperature (200-500 °C) operation, alkali nitrate-promoted MgO is a promising candidate; whose detailed reaction mechanisms are not yet fully understood, however. In the present study, we have performed a comprehensive investigation on the mechanisms of CO2 absorption and desorption of NaNO3-promoted MgO. Highly efficient CO2 absorbents were obtained by decomposing Mg5(CO3)4(OH)2·4H2O with NaNO3 intimately mixed with it. Our collective data, including isothermal CO2 uptake curves, MgO solubility in molten NaNO3, and observations on the reaction of MgO wafers with CO2, indicate that the absorption takes place in the molten NaNO3 medium in which both CO2 and MgO are dissolved. MgCO3 is formed inside the molten promoter through the nucleation and growth steps. The decomposition of MgCO3 back to MgO, that is desorption of CO2, is also facilitated by molten NaNO3, which we attribute to the decreased relative stability of MgCO3 with respect to MgO when in contact with molten NaNO3. The relative affinity of molten nitrate to MgO and MgCO3 was estimated by measuring the 'contact angles' of nitrate on them. Implications of our findings for the real applications of alkali nitrate-promoted MgO absorbents with numerous repeated cycles of absorption and desorption of CO2 are discussed.

  4. Survival of HCl( v=2) in trapping-desorption from MgO(100)

    Science.gov (United States)

    Korolik, M.; Suchan, M. M.; Johnson, M. J.; Arnold, D. W.; Reisler, H.; Wittig, C.

    2000-08-01

    An HCl molecular beam incident on MgO(100) is photoexcited to v=2, J=1 by using a pulsed parametric oscillator. At a translational energy of 0.11 eV, incident HCl is adsorbed. Thermal desorption yields v=2 molecules whose rotational and translational degrees of freedom are equilibrated at the surface temperature. Surface residence times for v=2 might be as long as 1 μs. At 180 K, it is concluded that a large fraction of surface-bound v=2 molecules reenter the gas phase, while at 120 K, deactivation exceeds desorption by an order of magnitude. Deactivation probably takes place at steps.

  5. Large-area thin self-supporting carbon foils with MgO coatings

    CERN Document Server

    Stolarz, A

    2002-01-01

    Large area self-supporting carbon foils in the thickness of range of 8-22 mu g/cm sup 2 , coated with approximately 4 mu g/cm sup 2 MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm sup 2. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  6. In situ investigation of the mobility of small gold clusters on cleaved MgO surfaces

    Science.gov (United States)

    Metois, J. J.; Heinemann, K.; Poppa, H.

    1976-01-01

    The mobility of small clusters of gold (about 10 A in diameter) on electron-beam-cleaved MgO surfaces was studied by in situ transmission electron microscopy under controlled vacuum and temperature conditions. During the first 10 min following a deposition at room temperature, over 10 per cent of the crystallites moved over short distances (about 20 A) discontinuously, with a velocity greater than 150 A/sec. Eighty per cent of the mobility events were characterized by the avoidance of proximity of other crystallites, and this was tentatively explained as the result of repulsive elastic forces between the interacting crystallites.

  7. The emission of atoms and molecules accompanying fracture of single-crystal MgO

    Science.gov (United States)

    Dickinson, J. T.; Jensen, L. C.; Mckay, M. R.; Freund, F.

    1986-01-01

    The emission of particles due to deformation and fracture of materials has been investigated. The emission of electrons (exoelectron emission), ions, neutral species, photons (triboluminescence), as well as long wavelength electromagnetic radiation was observed; collectively these emissions are referred to as fractoemission. This paper describes measurements of the neutral emission accompanying the fracture of single-crystal MgO. Masses detected are tentatively assigned to the emission of H2, CH4, H2O, CO, O2, CO2, and atomic Mg. Other hydrocarbons are also observed. The time dependencies of some of these emissions relative to fracture are presented for two different loading conditions.

  8. Structural and optical characterization of Er-alkali-metals codoped MgO nanoparticles synthesized by solution combustion route

    Science.gov (United States)

    Sivasankari, J.; Selvakumar Sellaiyan, S.; Sankar, S.; Devi, L. Vimala; Sivaji, K.

    2017-01-01

    Pure MgO, rare-earth (Er) doped MgO (MgO:Er), and alkali metal ions (Li, Na and K) co-doped MgO:Er [i.e. MgO: Er+X (X=Li, Na, and K)] nanopowders were synthesized by solution combustion method and characterized. The XRD analysis reveals the cubic structure and the substitution of dopants and co-dopants in MgO. Annealing at 800 °C, increases the sizes of nano-crystallites of all samples appreciably, indicating the grain growth and the improvement in crystallinity of all the samples. Increase in lattice parameter, d spacing and band gap were observed after annealing. Structural and morphological analysis using scanning electron microscope (SEM) and transmission electron microscope (TEM) studies has shown that the samples contain structures like agglomerated clusters. FT-IR spectra confirm the stretching mode of hydroxyl groups, carbonate and presence of MgO bonding. The characteristic wavelength ranging from 2600 cm-1 to 3000 cm-1 were assigned to transition of 4S3/2→4I13/2 and 4I11/2→4I15/2 of Er3+.

  9. Effects of incidence angle on the structure and properties of cathodic vacuum arc deposition MgO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, D.Y., E-mail: zhudy@gdut.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Experiment Teaching Department, Guangdong University of Technology, Guangzhou 510006 (China); Liu, Y. [College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Zheng, C.X.; Wang, M.D.; Chen, D.H. [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); He, Z.H., E-mail: stshzh@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2012-06-15

    MgO thin films, as the protective layers for plasma display panels (PDP), were prepared by using cathodic vacuum arc deposition technique. The influences of deposition angle between -60 Degree-Sign and 60 Degree-Sign on film structure and properties were investigated. X-ray diffraction (XRD), ellipsometer, thermal field emission environment scanning electron microscopy (SEM) and UV-Visible spectrophotometry were used to study the properties of MgO thin films like crystallization, surface structures, thicknesses and refraction indices. Our results show that the thickness of MgO thin film decreases with the increase of incidence angle. This is confirmed by the transmittance spectra as well. The film deposited at 0 Degree-Sign shows sharper diffraction peaks and smaller FWHMs (full width at half maximum) of both MgO (200) and (220), which means better crystallization quality of the film. The higher packing density is achieved on the 0 Degree-Sign deposited film as well. - Highlights: Black-Right-Pointing-Pointer The thickness of MgO thin film decreases with the increase of incidence angle. Black-Right-Pointing-Pointer Low-angle deposition can increase film deposition rate and improve its crystallinity. Black-Right-Pointing-Pointer Multi-arc setting or rotating substrate is necessary for uniform deposition.

  10. Fourier Transform Infrared Spectroscopy of the A1Π- X1Σ + System of MgO

    Science.gov (United States)

    Kagi, E.; Hirano, T.; Takano, S.; Kawaguchi, K.

    1994-11-01

    The gas-phase infrared absorption spectrum of the A1Π- X1Σ + system of MgO was observed in the 2700-5400 cm -1 region with a high-resolution Fourier transform infrared spectrometer. The MgO molecule was produced in a reaction of Mg vapor with N 2O. The observed 501 spectral lines were assigned to five vibrational bands, vA- vX = 1-0 2-0, 3-0, 2-1, and 0-1 of 24MgO. These lines were analyzed to determine the band origins, the rotational, centrifugal distortion, and Λ-type doubling constants in the A1Π state. The term value Te of the A1Π state was derived to be 3563.8377 (74) cm -1, with one standard deviation in parentheses. The rotational levels in the A1Π state were found to be perturbed by those of the vibrational levels of the X1Σ + state through rotational-electronic interaction, and the analysis of the perturbation was carried out to determine the interaction constants. The spectra of the vA- vX = 1-0 bands of the isotopic species, 25MgO and 26MgO, wer also observed and analyzed.

  11. Analysis of Waste Isolation Pilot Plan (WIPP) Underground and MGO Samples by the Savannah River National Laboratory (SRNL)

    Energy Technology Data Exchange (ETDEWEB)

    Young, J. [Savannah River Site (SRS), Aiken, SC (United States); Ajo, H. [Savannah River Site (SRS), Aiken, SC (United States); Brown, L. [Savannah River Site (SRS), Aiken, SC (United States); Coleman, C. [Savannah River Site (SRS), Aiken, SC (United States); Crump, S. [Savannah River Site (SRS), Aiken, SC (United States); Diprete, C. [Savannah River Site (SRS), Aiken, SC (United States); Diprete, D. [Savannah River Site (SRS), Aiken, SC (United States); Ekechukwu, A. [Savannah River Site (SRS), Aiken, SC (United States); Gregory, C. [Savannah River Site (SRS), Aiken, SC (United States); Jones, M. [Savannah River Site (SRS), Aiken, SC (United States); Missimer, D. [Savannah River Site (SRS), Aiken, SC (United States); O' Rourke, P. [Savannah River Site (SRS), Aiken, SC (United States); White, T. [Savannah River Site (SRS), Aiken, SC (United States)

    2014-12-31

    Analysis of the recent WIPP samples are summarized in this report; WIPP Cam Filters 4, 6, 9 (3, 7, 11 were analyzed with FAS-118 in a separate campaign); WIPP Drum Lip R16 C4; WIPP Standard Waste Box R15 C5; WIPP MgO R16 C2; WIPP MgO R16 C4; WIPP MgO R16 C6; LANL swipes of parent drum; LANL parent drum debris; LANL parent drum; IAEA Swipe; Unused “undeployed” Swheat; Unused “undeployed” MgO; and Masselin cloth “smears”. Analysis showed that the MgO samples were very pure with low carbonate and water content. Other samples showed the expected dominant presence of Mg, Na and Pb. Parent drum debris sample was mildly acidic. Interpretation of results is not provided in this document, but rather to present and preserve the analytical work that was performed. The WIPP Technical Analysis Team is responsible for result interpretation which will be written separately.

  12. Atomically Resolved Site-Isolated Catalyst on MgO: Mononuclear Osmium Dicarbonyls formed from Os3(CO)12.

    Science.gov (United States)

    Aydin, Ceren; Kulkarni, Apoorva; Chi, Miaofang; Browning, Nigel D; Gates, Bruce C

    2012-07-19

    Supported triosmium clusters, formed from Os3(CO)12 on MgO, were treated in helium at 548 K for 2 h, causing fragmentation of the cluster frame and the formation of mononuclear osmium dicarbonyls. The cluster breakup and the resultant fragmented species were characterized by infrared and X-ray absorption spectroscopies, and the fragmented species were imaged by scanning transmission electron microscopy. The spectra identify the surface osmium complexes as Os(CO)2{Osupport}n (n = 3 or 4) (where the braces denote support surface atoms). The images show site-isolated Os atoms in mononuclear osmium species on MgO. The intensity analysis on the images of the MgO(110) face showed that the Os atoms were located atop Mg columns. This information led to a model of the Os(CO)2 on MgO(110), with the distances approximated as those determined by EXAFS spectroscopy, which are an average over the whole MgO surface; the results imply that these complexes were located at Mg vacancies.

  13. Mechanisms of Vanadium Recovery from Stone Coal by Novel BaCO3/CaO Composite Additive Roasting and Acid Leaching Technology

    Directory of Open Access Journals (Sweden)

    Zhenlei Cai

    2016-03-01

    Full Text Available In this report, the vanadium recovery mechanisms by novel BaCO3/CaO composite additive roasting and acid leaching technology, including the phase transformations and the vanadium leaching kinetics, were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using BaCO3/CaO as the composite additive. The results indicated that during the composite additive BaCO3/CaO roasting process, the monoclinic crystalline structure of muscovite (K(Al,V2[Si3AlO10](OH2 was converted into the hexagonal crystalline structure of BaSi4O9 and the tetragonal crystalline structure of Gehlenite (Ca2Al2SiO7, which could, therefore, facilitate the release and extraction of vanadium. Vanadium in leaching residue was probably in the form of vanadate or pyrovanadate of barium and calcium, which were hardly extracted during the sulfuric acid leaching process. The vanadium leaching kinetic analysis indicated that the leaching process was controlled by the diffusion through a product layer. The apparent activation energy could be achieved as 46.51 kJ/mol. The reaction order with respect to the sulfuric acid concentration was 1.1059. The kinetic model of vanadium recovery from stone coal using novel composite additive BaCO3/CaO could be finally established.

  14. First measurement of the dissociative recombination of CaO+ with electrons brings closure to Ca ion recycling chemistry in the lower thermosphere

    Science.gov (United States)

    Bones, David; Plane, John

    2016-04-01

    Modelling the temporal and spatial extent of the metal layers in the mesosphere/lower thermosphere requires knowledge of the rate coefficients of dissociative recombination of metal oxide ions with electrons. Previously, these coefficients have been assumed to be 3 × 10-7 cm3 s-1 at 200 K. In this study the coefficient has been measured directly for the dissociative recombination of CaO+. Measurements are made in a flowing afterglow system with a Langmuir probe. Calcium oxide ions are introduced into an argon ion/electron plasma by pulsed laser ablation of a solid target. The relative concentration of CaO+ is measured by a quadrupole mass spectrometer as a function of flow rate (3 - 5 slm), which is inversely proportional to the reaction time of the CaO+ ions with the electrons in the plasma (2.1 to 3.5 ms). Charge transfer reactions between argon ions and neutral molecules complicate the analysis. A kinetic model describing gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data to extract the DR rate coefficient for CaO+. Unlike other metals present in the atmosphere, Ca+ ions are far more abundant than neutral Ca. The new DR rate coefficient is used to explore possible reasons for this anomaly in a model of meteor-ablated calcium in the mesosphere and lower thermosphere.

  15. Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

    Institute of Scientific and Technical Information of China (English)

    V.H.Rane; S.T.Chaudhari; V.R.Choudhary

    2008-01-01

    Surface properties (viz. surface area, basicity/base strength distribution, and crystal phases) of alkali metal doped CaO (alkali metal/Ca = 0.1 and 0.4) catalysts and their catalytic activity/selectivity in oxidative coupling of methane (OCM) to higher hydrocarbons at different reaction conditions (viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm3·g-1·h-1) have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties (viz. surface area, basicity/base strength distribution) and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity (strong basic sites) and the C2+ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO (Na/Ca = 0.1, before calcination) catalyst (calcined at 750 ℃), showed best performance (C2+selectivity of 68.8% with 24.7% methane conversion), whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

  16. Significance of the structural properties of CaO catalyst in the production of biodiesel: An effect on the reduction of greenhouse gases emission

    Directory of Open Access Journals (Sweden)

    Ljupković Radomir B.

    2014-01-01

    Full Text Available The influence of the physicochemical properties of a series of CaO catalysts activated at different temperatures on the biodiesel production was investigated. These catalysts show dissimilar yields in the transesterification of triglycerides with methanol. We have found significant relationships between structural properties (the type of the pore system, the typical CaO crystal phase and the sizes of crystallites (up to 25 nm, the minimal weight percentage of CaO phase, the total surface basicity and potential existence of two types of basic active sites of CaO prepared and activated by means of thermal treatment at highest temperature and catalytic efficiency. Benefits of this catalyst are short contact time, standard operating temperature and atmospheric conditions, relatively low molar ratios and small catalyst loading. These all together resulted in a very high biodiesel yield of high purity. The properties of different biodiesel (obtained with the use of the prepared CaO catalyst blends with different diesel and biodiesel ratios indicate that the higher the fraction of biodiesel fuel the better the achieved fuel properties according to the EU standards. A significant reduction of CO2 and CO emissions and only a negligible NOx increase occurred when blends with an increased biodiesel portion was used. The use of biodiesel derived blends, and the eventual complete replacement of fossil fuels with biodiesel as a renewable, alternative fuel for diesel engines, would greatly contribute to the reduction of greenhouse gases emissions. [Projekat Ministarstva nauke Republike Srbije, br. ON 172061 i TR 34008

  17. Nickel catalysts supported on MgO with different specific surface area for carbon dioxide reforming of methane

    Institute of Scientific and Technical Information of China (English)

    Luming; Zhang; Lin; Li; Yuhua; Zhang; Yanxi; Zhao; Jinlin; Li

    2014-01-01

    In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. The results showed that MgO support with the higher specific surface area led to the higher dispersion of the active metal, which resulted in the higher initial activity. On the other hand, the specific surface area of MgO materials might not be the dominant factor for the basicity of support to chemisorb and activate CO2, which was another important factor for the performance of catalysts. Herein, Ni/MgO(CA) catalyst with proper specific surface area and strong ability to activate CO2exhibited stable catalytic property and the carbon species deposited on the Ni/MgO(CA) catalyst after 10 h of reaction at 650 ?C were mainly activated carbon species.

  18. Sensitive Evaluation on Early Cracking Tendency of Concrete with Inclusion of Light-burnt MgO

    Institute of Scientific and Technical Information of China (English)

    CHEN Xia; YANG Huaquan; Zhou Shihua; LI Wenwei

    2011-01-01

    The advanced temperature and stress test machine was introduced to determine the early cracking tendency of concrete with inclusion of light-burnt MgO under full restraint by tracking the development of thermal,physical and deformation properties.Results showed that light-burnt MgO being incorporated ranging between 4 wt% and 6 wt% of cementitious materials was beneficial to increase the maximum compressive stress and cracking stress of concrete by 0.37 MPa and 0.2 MPa on average respectively.The second zero stress temperature was reduced by 11.4 ℃ and the maximum temperature was slightly reduced while cracking thermal impact was significantly enhanced from 59.8 ℃ to 66.2 ℃.Sensitive anti-cracking coefficient F was forwarded to assess the early cracking tendency of concrete and the inclusion of 4 wt% lightburnt MgO with activity of 109 s ranked the best in crack resistance.

  19. Effect of stabilizer on optical and structural properties of MgO thin films prepared by sol–gel method

    Indian Academy of Sciences (India)

    Z Bazhan; F E Ghodsi; J Mazloom

    2013-10-01

    The effects of monoethanolamine (MEA) and acetylacetone (ACAC) addition as stabilizer on the crystallization behaviour, morphology and optical properties of magnesium oxide were investigated using thermogravimetry (TG/DTG), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible, photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy. Stabilizer addition reduces transparency of the films. MgO films prepared at 500 °C showed weak orientation of (200). However, the films prepared by addition of stabilizer are amorphous. MgO powders were prepared for exhibiting the structural properties. The patterns of MgO powders showed a preferred orientation of (200). The addition of stabilizer causes a reduction in grain size. SEM micrographs show that a homogenous and crack-free film can be prepared at 500 °C and addition of stabilizer causes an increase in packing density.

  20. 365 nm photon-induced dynamics of ClNO adsorbed on MgO(100)

    Science.gov (United States)

    Ferkel, H.; Hodgson, L.; Singleton, J. T.; Blass, P. M.; Reisler, H.; Wittig, C.

    1994-06-01

    Temperature programmed desorption (TPD) and 365 nm photolysis of ClNO adsorbed on MgO(100) at 90 K were investigated under ultrahigh vacuum conditions. The crystal was treated in a way that largely eliminated oxygen vacancies and yielded a relatively smooth surface. Angularly resolved time-of-flight (TOF) mass spectra and state-selective resonance-enhanced multiphoton ionization (REMPI) spectra of NO photoproducts were obtained. The TPD data indicate that ClNO desorbs at surface temperatures above 160 K for exposures (Θ) below 0.2 Langmuirs (L), while for higher values of Θ the main desorption peak is near 120 K. The higher temperature feature, which saturates at Θ˜0.3 L, is probably associated with binding to defect sites. Thermal desorption is believed to be molecular at all coverages. Irradiation at 365 nm for 0.1≤Θ≤5.0 L yields products having low average translational energies and broad translational energy distributions. NO fragment REMPI spectra were recorded at Θ≥0.7 L. The rotational distributions could be fit with a temperature of 110±10 K, i.e., comparable to that of the substrate. These results differ from those obtained in the photodissociation of gas-phase ClNO, where the NO fragment has high translational and rotational energies. However, the present results are similar to those obtained on rougher MgO(100) surfaces. Possible mechanisms are discussed.

  1. Superior MgH2 Kinetics with MgO Addition: A Tribological Effect

    Directory of Open Access Journals (Sweden)

    Kondo-Francois Aguey-Zinsou

    2012-08-01

    Full Text Available The kinetics of hydrogen absorption/desorption in magnesium can be improved without any catalysis assistance and MgO was found to be more effective than the best catalyst reported so far, i.e., Nb2O5. Herein, a quantitative analysis of the hydrogen kinetics in magnesium modified with MgO was performed in order to identify possible rate controlling mechanisms. While hydrogen absorption was found to be diffusion controlled as commonly reported, hydrogen desorption evolved from nucleation and growth to an interface controlled process depending on the desorption temperature. Comparison with the effect of Nb2O5 indicates that similar rate limiting steps occur regardless of the oxide additive. These findings are reconciled by considering the tribological effect of solid oxide additives, as a correlation between oxides electronegativity and improvement in hydrogen kinetics was found. Such a correlation clearly highlights the mechanical effect of solid oxides in facilitating the grinding and stabilisation of small magnesium particles for efficient and fast hydrogen kinetics.

  2. MgO nano-facet embedded silver-based dielectric/metal/dielectric transparent electrode.

    Science.gov (United States)

    Kim, Sungjun; Yu, Hak Ki; Hong, Kihyon; Kim, Kisoo; Son, Jun Ho; Lee, Illhwan; Kim, Kyoung-Bo; Kim, Tae-Yeob; Lee, Jong-Lam

    2012-01-16

    We replace Indium Tin Oxide (ITO) with an MgO nano-facet Embedded WO(3)/Ag/WO(3)(WAW) multilayer for electrodes of high efficiency OLEDs. WAW shows higher values for transmittance (93%) and conductivity (1.3×10(5) S/cm) than those of ITO. Moreover, WAW shows higher transmittance (92.5%) than that of ITO (86.4%) in the blue region (<500 nm). However, due to the large difference in refractive indices (n) of glass (n=1.55) and WO(3) (n=1.95), the incident light has a small critical angle (52°). Thus, the generated light is confined by the glass/WAW interface, resulting in low light outcoupling efficiency (~20%). This can be enhanced by using a nano-facet structured MgO (n=1.73) layer and a ZrO(2) (n=1.84) layer as a graded index layer. Using these optimized electrodes, ITO-free, OLEDs with various emission wavelengths have been produced. The luminance of OLEDs using MgO/ZrO(2)/WAW layers is enhanced by 24% compared to that of devices with ITO.

  3. Effect of MgO on Oxidation Process of Fe3 O4 in Pellets

    Institute of Scientific and Technical Information of China (English)

    Qiang-jian GAO; Yan-song SHEN; Xin JIANG; Hai-yan ZHENG; Feng-man SHEN; Chang-sheng LIU

    2016-01-01

    Induration process of oxidized pellets involves the oxidation of Fe3 O4 and re-crystallization of Fe2 O3 .The oxidation process of Fe3 O4 is significant for pellets to obtain better ambient strength.Thus,the effect of MgO on oxidation process of Fe3 O4 was investigated.The unreacted core model was applied to analyze the oxidizing indura-tion process of pellets.The experimental results show that MgO plays a negative role in the oxidation process of Fe3 O4 .The oxidation rate of Fe3 O4 in MgO-fluxed pellets (95.0% Fe3 O4+5.0% MgO)is slower than that in standard acid pellets (100% Fe3 O4 ).The relation between oxidation ratio of Fe3 O4 and time was calculated based on the unreacted core model for both MgO-fluxed pellets and standard acid pellets.According to verification experi-ments,the values calculated by model coincide well with the experimental values.Therefore,the unreacted core model could be applied to describe the oxidizing induration process of pellets.

  4. XMCD study of CoPt nanoparticles embedded in MgO and amorphous carbon matrices

    Energy Technology Data Exchange (ETDEWEB)

    Tournus, F. [Universite de Lyon, F-69000, France and Univ. Lyon 1, Laboratoire PMCN, CNRS, UMR 5586, F69622 Villeurbanne Cedex (France)], E-mail: ftournus@lpmcn.univ-lyon1.fr; Blanc, N.; Tamion, A. [Universite de Lyon, F-69000, France and Univ. Lyon 1, Laboratoire PMCN, CNRS, UMR 5586, F69622 Villeurbanne Cedex (France); Ohresser, P. [Synchrotron SOLEIL, BP 48, 91192 Gif sur Yvette (France); Perez, A.; Dupuis, V. [Universite de Lyon, F-69000, France and Univ. Lyon 1, Laboratoire PMCN, CNRS, UMR 5586, F69622 Villeurbanne Cedex (France)

    2008-11-15

    We report the synthesis and characterization of CoPt nanoparticles, using X-ray magnetic circular dichroism (XMCD) at the Co L{sub 2,3} edges. Clusters are produced in ultra-high vacuum conditions, following a physical route, and embedded in non-metallic matrices: MgO and amorphous carbon (a-C). In MgO, Co atoms are partially oxidized, which goes with a {mu}{sub L}/{mu}{sub S} enhancement. On the contrary, a-C appears as a very suitable matrix. In particular, annealing of CoPt cluster embedded in a-C is able to promote L 1{sub 0} chemical order, without alteration of the sample. This transformation, which has been directly evidenced by transmission electron microscopy observations, is accompanied by a striking augmentation of {mu}{sub S}, {mu}{sub L} and the {mu}{sub L}/{mu}{sub S} ratio of Co. The presence of Pt leads to an enhanced Co magnetic moment, as compared to Co bulk, even for the chemically disordered alloy. Moreover, the high value of 1.91{mu}{sub B}/at. measured for {mu}{sub S} is unusual for Co and must be a signature of chemical order in CoPt alloy nanoparticles.

  5. Annealing Effects on the Surface Plasmon of MgO Implanted with Gold

    Science.gov (United States)

    Ueda, A.; Mu, R.; Tung, Y. -S.; Henderson, D. O.; White, C. W.; Zuhr, R. A.; Zhu, Jane G.; Wang, P. W.

    1997-01-01

    Gold ion implantation was carried out with the energy of 1.1 MeV into (100) oriented MgO single crystal. Implanted doses are 1, 3, 6, 10 x 10(exp 16) ions/sq cm. The gold irradiation results in the formation of gold ion implanted layer with a thickness of 0.2 microns and defect formation. In order to form gold colloids from the as-implanted samples, we annealed the gold implanted MgO samples in three kinds of atmospheres: (1)Ar only, (2)H2 and Ar, and (3)O2 and Ar. The annealing over 1200 C enhanced the gold colloid formation which shows surface plasmon resonance band of gold. The surface plasmon bands of samples annealed in three kinds of atmospheres were found to be at 535 nm (Ar only), 524 nm(H2+Ar), and 560 nm (02+Ar), The band positions of surface plasmon can be reversibly changed by an additional annealing.

  6. Fabrication of all-MgB Josephson junctions using MgO insulator layer

    Energy Technology Data Exchange (ETDEWEB)

    Oba, T. [Graduate School of Engineering, Iwate University, 4-3-5, Ueda, Morioka 020-8551 (Japan); Goto, S. [Lightom, 95-2 Sugo, Takizawa 020-0173 (Japan); Sasaki, S.; Nakanishi, Y.; Fujino, T. [Graduate School of Engineering, Iwate University, 4-3-5, Ueda, Morioka 020-8551 (Japan); Harada, Y. [JST Satellite Iwate, Japan Science and Technology Agency, 3-35-2 Iiokashinden, Morioka, Iwate 020-0852 (Japan); Nakamura, M. [Graduate School of Engineering, Iwate University, 4-3-5, Ueda, Morioka 020-8551 (Japan); Saito, A. [Department of Electrical Engineering, Yamagata University, 4-3-16, Jonan, Yonezawa, Yamagata 992-8510 (Japan); Yoshizawa, M. [Graduate School of Engineering, Iwate University, 4-3-5, Ueda, Morioka 020-8551 (Japan)], E-mail: yosizawa@iwate-u.ac.jp

    2008-09-15

    We report on the fabrication and properties of all-MgB{sub 2} tunnel junctions with an MgO barrier. Superconductor-insulator-superconductor (SIS) junctions were fabricated on C-plane sapphire substrates. MgB{sub 2} films were grown in an ultra-high vacuum in the 10{sup -9} Torr range. The MgO insulating layer was evaporated using an electron-beam gun. SIS junctions of 30 {mu}m in diameter were fabricated by standard photolithography and Ar ion milling techniques. The critical temperature (T{sub C}) of the lower MgB{sub 2} layer after the SIS junction fabrication process was 36.7 K, which remained the same as that of the bare MgB{sub 2} film. We observed tunneling behavior in the current-voltage (I-V) characteristics of the present junctions. A superconducting gap was clearly observed at around 2.7 mV (=2{delta})

  7. Damage accumulation in MgO irradiated with MeV Au ions at elevated temperatures

    Science.gov (United States)

    Bachiller-Perea, Diana; Debelle, Aurélien; Thomé, Lionel; Behar, Moni

    2016-09-01

    The damage accumulation process in MgO single crystals under medium-energy heavy ion irradiation (1.2 MeV Au) at fluences up to 4 × 1014 cm-2 has been studied at three different temperatures: 573, 773, and 1073 K. Disorder depth profiles have been determined through the use of the Rutherford backscattering spectrometry in channeling configuration (RBS/C). The analysis of the RBS/C data reveals two steps in the MgO damage process, irrespective of the temperature. However, we find that for increasing irradiation temperature, the damage level decreases and the fluence at which the second step takes place increases. A shift of the damage peak at increasing fluence is observed for the three temperatures, although the position of the peak depends on the temperature. These results can be explained by an enhanced defect mobility which facilitates defect migration and may favor defect annealing. X-ray diffraction reciprocal space maps confirm the results obtained with the RBS/C technique.

  8. A vinyl acetate sensor based on cataluminescence on MgO nanoparticles.

    Science.gov (United States)

    Wu, Chen Chou; Cao, Xiaoan; Wen, Qiang; Wang, Zehua; Gao, Qianqian; Zhu, Huichang

    2009-10-15

    A novel cataluminescence (CTL) sensor using nanosized MgO as the sensing material for determination of the trace of vinyl acetate in air was proposed in the present study. Eight catalysts were examined and the results showed that the CTL intensity on MgO nanoparticles was the strongest. Under the optimized conditions, the linear range of the CTL intensity versus the concentration of vinyl acetate vapor was 2-2000 ppm with a detection limit of 1.0 ppm (3sigma) and a relative standard deviation (R.S.D.) of 1.18% for five times determination of 1000 ppm vinyl acetate. There were no CTL emissions when foreign substances, including ammonia, benzene, acetic acid, formaldehyde and ethyl acetate, passed through the sensor. CTL emissions were detected for methanol, ethanol and acetaldehyde at levels around 5.5%, 10.1% and 13.4% compared with the responsed vinyl acetate. The sensor had a long lifetime more than 100 h.

  9. Superconducting YBCO thin film on multicrystalline Ag film evaporated on MgO substrate

    Science.gov (United States)

    Azoulay, Jacob; Verdyan, Armen; Lapsker, Igor

    Superconducting YBa 2Cu 3O 7-δ films were grown by resistive evaporation on multicrystalline silver film which was evaporated on MgO substrate. A simple inexpensive vacuum system equipped with resistively heated boat was used for the whole process. Silver film was first evaporated on MgO substrate kept at 400°C during the evaporation after which with no further annealing a precursor mixture of yttrium small grains and Cu and BaF2 in powder form weighed in the atomic proportion to yield stoichiometric YBa 2Cu 3O 7 was evaporated. The films thus obtained were annealed at 740°C under low oxygen partial pressure of about 1Pa for 30 minutes to form the superconducting phase. X-ray diffraction and scanning electron microscopy techniques were used for texture and surface analysis. Electrical properties were determined using a standard dc four-probe for electrical measurements. The physical and electrical properties of the YBCO films are discussed in light of the fact that X-ray diffraction measurements done on the silver film have revealed a multicrystalline structure

  10. NO2 interaction with Au atom adsorbed on perfect and defective MgO(100) surfaces: density functional theory calculations.

    Science.gov (United States)

    Ammar, H Y; Eid, Kh M

    2013-10-01

    The interactions of nitrogen dioxide molecule (NO2) on Au atom adsorbed on the surfaces of metal oxide MgO (100) on both anionic (O2-) and defect (F(s) and F(s)(+)-centers) sites have been studied using the Density Functional Theory (DFT) in combination with embedded cluster model. The adsorption energies of NO2 molecule (N-down as well as O-down) on O(-2), F(s) and F(s)(+)-sites were considered. Full optimization for the additive materials and partial optimization for MgO substrate surfaces have been done. The formation energies were evaluated for F(s) and F(s)(+) of MgO substrate surfaces. Some parameters, the Ionization Potential (IP) and electron Affinity (eA), for defect free and defect containing surfaces have been calculated. The interaction properties of NO2 have been analyzed in terms of the adsorption energy, the electron donation (basicity), the elongation of N-O bond length and the charge distribution by using Natural Bond Orbital (NBO) analysis. The adsorption properties were examined by calculation of the Density of State (DOS). The presence of the Au atom increases the surface chemistry of the anionic O(2-)-site of MgO substrate surfaces. On the other hand, the presence of the Au atom decreases the surface chemistry of the F(s) and F(s)(+)-sites of MgO substrate surfaces. Generally, the NO2 molecule is strongly adsorbed (chemisorption) on the MgO substrate surfaces containing F(s) and F(s)(+)-centers.

  11. Strong electric fields at a prototypical oxide/water interface probed by ab initio molecular dynamics: MgO(001).

    Science.gov (United States)

    Laporte, Sara; Finocchi, Fabio; Paulatto, Lorenzo; Blanchard, Marc; Balan, Etienne; Guyot, François; Saitta, Antonino Marco

    2015-08-21

    We report a density-functional theory (DFT)-based study of the interface of bulk water with a prototypical oxide surface, MgO(001), and focus our study on the often-overlooked surface electric field. In particular, we observe that the bare MgO(001) surface, although charge-neutral and defectless, has an intense electric field on the Å scale. The MgO(001) surface covered with 1 water monolayer (1 ML) is investigated via a supercell accounting for the experimentally-observed (2 × 3) reconstruction, stable at ambient temperature, and in which two out of six water molecules are dissociated. This 1 ML-hydrated surface is also found to have a high, albeit short-ranged, normal component of the field. Finally, the oxide/water interface is studied via room-temperature ab initio molecular dynamics (AIMD) using 34 H2O molecules between two MgO(001) surfaces. To our best knowledge this is the first AIMD study of the MgO(001)/liquid water interface in which all atoms are treated using DFT and including several layers above the first adsorbed layer. We observe that the surface electric field, averaged over the AIMD trajectories, is still very strong on the fully-wet surface, peaking at about 3 V Å(-1). Even in the presence of bulk-like water, the structure of the first layer in contact with the surface remains similar to the (2 × 3)-reconstructed ice ad-layer on MgO(001). Moreover, we observe proton exchange within the first layer, and between the first and second layers - indeed, the O-O distances close to the surface are found to be distributed towards shorter distances, a property which has been shown to directly promote proton transfer.

  12. Ligand/cluster/support catalytic complexes in heterogeneous ultrananocatalysis: NO oxidation on Ag3/MgO(100).

    Science.gov (United States)

    Sementa, Luca; Barcaro, Giovanni; Negreiros, Fabio R; Fortunelli, Alessandro

    2014-12-28

    In the present work we explore via first-principles simulations whether the ligand/cluster/support catalytic complex generated by CO oxidation over silver trimers deposited on the regular MgO(100) surface - i.e. a Ag3/carbonate or Ag3(CO3)/MgO(100) species - can be used as a catalyst in a different reaction: the selective oxidation of NO to NO2 (or NOox). The Ag3(CO3)/MgO(100) complex is first shown to be reasonably stable at room temperature in terms of both disaggregation and sintering, and that it can be generated from Ag3 adsorbed onto an oxygen vacancy defect of the regular MgO(100) surface under oxidation conditions. It is then found that the Ag3(CO3)/MgO(100) species transforms under NOox conditions into an even more complex aggregate, a mixed carbonate/double-nitrite Ag3(CO3)(NO2)2/MgO(100) species, which can then act as an efficient catalyst of NOox. It is noteworthy that under NOox reaction conditions a different ligand/cluster/support catalytic complex is formed with respect to the original COox one. These findings prove the diversity of the catalytic chemistry of subnanometer (or ultranano) metal clusters deposited on oxide substrates, associated with the formation of many different ligand/cluster/support aggregates, the vast amount of combinatorial possibilities thus opening, and the need for computational approaches to perform systematic structural and stoichiometric searches in order to cope with such a multiform diversity.

  13. MgO thin films deposited by electrostatic spray pyrolysis for protecting layers in AC-plasma display panel

    CERN Document Server

    Kim, S G

    1999-01-01

    MgO thin films were deposited on SiO sub 2 (100) substrates by using electrostatic spray pyrolysis and Mg(tmhd) sub 2 as the precursor. The growth rates of the films varyed from 34 to 87 A/min and were measured for various substrate and guide temperatures. X-ray diffraction analysis provide evidence that the MgO films deposited at temperatures as low as 400 approx 500 .deg. C had preferred orientation to (100) plane perpendicular to the substrate surface. X-ray photoelectron spectroscopy and Auger electron spectroscopy data indicated that there were few organics incorporated in the films.

  14. Tailoring the microstructure of porous MgO supports for asymmetric oxygen separation membranes: Optimization of thermoplastic feedstock systems

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Clemens, F.; Glasscock, Julie

    2014-01-01

    Porous magnesium oxide (MgO) structures were prepared by thermoplastic processing for use as supports in asymmetric thin film oxygen transport membranes (OTMs). The open porosity, pore size distribution, and resulting gas permeability of the MgO structures were measured for different feedstock...... that the unexpected increase in gas permeability at temperatures above 1300 °C was a result of the growth of macro‐pores and the opening of bottle‐neck pores which resulted in improved pore connectivity. Mercury intrusion porosimetry experiments confirmed an increase in average pore size for samples sintered above...

  15. Tailoring the porosity and shrinkage of extruded MgO support tubes for oxygen separation membranes by thermoplastic feedstock development

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Kaiser, Andreas; Glasscock, Julie

    optimized with respect to flow behavior, co-sintering and final layer properties. Crucial parameters, such as similar flow resistance and linear shrinkage for both materials are necessary to achieve asymmetric structure successfully. Porosity above 30% and final grain size for the MgO support...... is investigated by varying amounts of pore former, polymer content and different pre-calcination temperatures of the as received MgO powder. Thermal analysis (TG/DTA) and dilatometry were employed to optimize de-bindering and sintering regime in order to achieve desired support porosity and defect free structure....

  16. Spontaneous dehydrogenation of methanol over defect-free MgO(100) thin film deposited on molybdenum

    CERN Document Server

    Song, Zhenjun

    2016-01-01

    The dehydrogenation reaction of methanol on metal supported MgO(100) films has been studied by employing periodic density functional calculations. As far as we know, the dehydrogenation of single methanol molecule over inert oxide insulators such as MgO has never been realized before without the introduction of defects and low coordinated atoms. By depositing the very thin oxide films on Mo substrate we have successfully obtained the dissociative state of methanol. The dehydrogenation reaction is energetically exothermic and nearly barrierless. The metal supported thin oxide films studied here provide a versatile approach to enhance the activity and properties of oxides.

  17. Desulfurization and oxidation behavior of ultra-fine CaO particles prepared from brown coal; Kattan wo mochiite choseishita CaO chobiryushi no datsuryu tokusei to sanka tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Benjamin, G.; Roman, M.; Yamazaki, Y.; Abe, H.; Harano, Y.; Takarada, Y. [Gunma University, Gunma (Japan). Faculty of Engineering

    1996-10-28

    The effect of reaction temperature and oxygen concentration on the desulfurization and oxidation behavior of ion-exchanged brown coal by Ca as new desulfurizing agent was studied. In experiment, Yallourn coal was used for ion- exchange, and limestone produced in Tochigi prefecture was also used for comparative study. Ca-exchanged brown coal was prepared by agitating coal in Ca(OH)2 slurry for 24 hours. The desulfurization behavior of a desulfurizing agent was obtained by measuring H2S and sulfur compounds in outlet gas of a reactor, and the oxidation behavior by measuring SO2 emission in outlet gas after oxidation reaction. As the experimental result, CaO produced from Ca-exchanged brown coal offered the extremely high activity to desulfurization reaction in a temperature range of 850-950{degree}C as compared with limestone. Although the oxidation behavior was dependent on oxidation temperature and oxygen concentration, CaS obtained from Ca-exchanged brown coal was more rapidly converted to CaSO4 than limestone. 3 refs., 8 figs., 2 tabs.

  18. Roles of MgO release from polyethylene glycol 6000-based solid dispersions on microenvironmental pH, enhanced dissolution and reduced gastrointestinal damage of telmisartan.

    Science.gov (United States)

    Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Lee, Seung Aeon; Nho, Vo Hong; Chi, Sang-Cheol; Lee, Beom-Jin

    2011-05-01

    The roles of magnesium oxide (MgO) release from solid dispersions (SDs) in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and water were investigated to elucidate the enhanced dissolution and reduced intestinal damages of telmisartan as a model drug. The polyethylene glycol 6000 (PEG 6000) was used to prepare the SDs. Three SDs were prepared: SD1 (PEG, MgO, TEL), SD2 (PEG 6000, TEL), SD3 (MgO, TEL). The physical mixture (PM) consisting of SD2 and MgO was also prepared. A binary SD without MgO (SD2) was also prepared for comparison in microenvironmental pH (pH(M)) modulation. The faster MgO released, the less control of pH(M) and the less enhanced dissolution of TEL were in consequences. SD3 increased dissolution in SIF and water (about 67%). Interestingly, ternary SD1 showed almost complete dissolution in all three media but dissolution of PM was the lowest due to the fast release of MgO and poor modulation of pH(M). MgO did not change the drug crystallinity but did have a strong molecular interaction with the drug. Additionally, the SD3-bearing tablet quickly increased pH(M) but then gradually decreased due to faster release of MgO while the SD1-bearing tablet gradually increased pH(M) at all fractional dimensions of the tablet by the MgO slowly released. The pH(M) of PM-bearing tablets was not varied as a function of time. Thus, the MgO-bearing SD1 also minimized gastrointestinal tissue damage caused by the model drug.

  19. The mass balance calculation of hydrothermal alteration in Sarcheshmeh porphyry copper deposit

    Directory of Open Access Journals (Sweden)

    Mohammad Maanijou

    2013-10-01

    Full Text Available Sarcheshmeh porphyry copper deposit is located 65 km southwest of Rafsanjan in Kerman province. The Sarcheshmeh deposit belongs to the southeastern part of Urumieh-Dokhtar magmatic assemblage (i.e., Dehaj-Sarduyeh zone. Intrusion of Sarcheshmeh granodiorite stock in faulted and thrusted early-Tertiary volcano-sedimentary deposits, led to mineralization in Miocene. In this research, the mass changes and element mobilities during hydrothermal process of potassic alteration were studied relative to fresh rock from the deeper parts of the plutonic body, phyllic relative to potassic, argillic relative to phyllic and propylitic alteration relative to fresh andesites surrounding the deposit. In the potassic zone, enrichment in Fe2O3 and K2O is so clear, because of increasing Fe coming from biotite alteration and presence of K-feldspar, respectively. Copper and molybdenum enrichments resulted from presence of chalcopyrite, bornite and molybdenite mineralization in this zone. Enrichment of SiO2 and depletion of CaO, MgO, Na2O and K2O in the phyllic zone resulted from leaching of sodium, calcium and magnesium from the aluminosilicate rocks and alteration of K-feldspar to sericite and quartz. In the argillic zone, Al2O3, CaO, MgO, Na2O and MnO have also been enriched in which increasing Al2O3 may be from kaolinite and illite formation. Also, enrichment in SiO2, Al2O3 and CaO in propylitic alteration zone can be attributed to the formation of chlorite, epidote and calcite as indicative minerals of this zone.

  20. ¿Caos en el electrocardiograma de estudiantes con miedo a volar? Un análisis de no linealidad

    Directory of Open Access Journals (Sweden)

    Jordi Llabrés

    2005-01-01

    Full Text Available La Teoría del Caos proporciona una nueva forma de analizar las respuestas psicofisiológicas asociadas a los trastornos de ansiedad. Pero para poder aplicar los métodos de análisis no lineal de esta relativamente reciente teoría, primero es necesario comprobar la existencia de algún tipo de no linealidad que justifique su uso. En este estudio experimental se analiza, mediante el procedimiento de los datos vicarios, la no linealidad de las señales generadas por el sistema cardiovascular (ECG de estudiantes con y sin miedo a volar, en diferentes condiciones de estimulación. Los errores de predicción de las series vicarias fueron siempre mayores que los de las correspondientes series empíricas (p < 0,05, demostrándose así que las señales ECG, en todos los sujetos y en todas las condiciones, presentan propiedades no lineales y que por tanto resulta adecuado analizarlas desde planteamientos no lineales para obtener conocimiento acerca de su complejidad, entropía, regularidad, etc.

  1. Interaction of free-base tetraphenylporphyrin with magnesium oxide: Influence of MgO morphology on metalation

    Science.gov (United States)

    Di Filippo, Gianluca; Classen, Andrej; Pöschel, Rebecca; Fauster, Thomas

    2017-02-01

    Using x-ray photoemission spectroscopy, we investigated the self-metalation of free-base tetraphenylporphyrin (2HTPP) on thin MgO(100) films on Ag(100). The deposition of one monolayer 2HTPP on MgO results in the formation of magnesium(ii) tetraphenylporphyrin (MgTPP) at room temperature. We demonstrate that the efficiency of the reaction drastically depends on the morphology of the oxide layers. The latter is changed by varying the substrate temperature during the oxide growth. We observe the complete metalation of the 2HTPP monolayer when the MgO films are grown at 393 K. The increase of the growth temperature to 573 K leads to the reduction of the percentage of metalated molecules to ˜50 % . We ascribe these results to the fact that MgTPP formation takes place through the hydroxilation of steps and defects on the MgO surface, which leads to an increase of the OH component in the O 1s line.

  2. Facile synthesis of MgO and Ni-MgO nanostructures with enhanced adsorption of methyl blue dye

    Science.gov (United States)

    Mohamed, R. M.; Shawky, Ahmed; Mkhalid, I. A.

    2017-02-01

    Nanostructured Magnesium oxide (MgO) was prepared by a simple method using a non-ionic block copolymer as surfactant. Ni was introduced to MgO to improve surface properties. The effect of Ni loading on the MgO crystalline structure, surface morphology and magnetic properties was observed by powder X-ray diffraction, field-emission scanning electron microscopy and a vibrating sample magnetometer, respectively. Textural properties of produced samples were investigated by nitrogen adsorption-desorption isotherms and the Brunauer-Emmett-Teller method. The as-prepared samples were employed as an adsorbent for the removal of Methyl blue (MeB) dye. The adsorption isotherms were studied using the Langmuir model. The results show a high adsorptive behavior for relatively high concentrated MeB with a maximum adsorption capacity of 367 mg g-1 indicating the enhanced adsorption performance of our produced structures. A mechanism for adsorption of MeB molecules on the prepared MgO is proposed.

  3. Self-healing of drying shrinkage cracks in cement-based materials incorporating reactive MgO

    Science.gov (United States)

    Qureshi, T. S.; Al-Tabbaa, A.

    2016-08-01

    Excessive drying shrinkage is one of the major issues of concern for longevity and reduced strength performance of concrete structures. It can cause the formation of cracks in the concrete. This research aims to improve the autogenous self-healing capacity of traditional Portland cement (PC) systems, adding expansive minerals such as reactive magnesium oxide (MgO) in terms of drying shrinkage crack healing. Two different reactive grades (high ‘N50’and moderately high ‘92-200’) of MgO were added with PC. Cracks were induced in the samples with restraining end prisms through natural drying shrinkage over 28 days after casting. Samples were then cured under water for 28 and 56 days, and self-healing capacity was investigated in terms of mechanical strength recovery, crack sealing efficiency and improvement in durability. Finally, microstructures of the healing materials were investigated using FT-IR, XRD, and SEM-EDX. Overall N50 mixes show higher expansion and drying shrinkage compared to 92-200 mixes. Autogenous self-healing performance of the MgO containing samples were much higher compared to control (only PC) mixes. Cracks up to 500 μm were sealed in most MgO containing samples after 28 days. In the microstructural investigations, highly expansive Mg-rich hydro-carbonate bridges were found along with traditional calcium-based, self-healing compounds (calcite, portlandite, calcium silicate hydrates and ettringite).

  4. Novel Approach for the Reduction of ZnO and MgO Using a Direct Diode-Laser

    Science.gov (United States)

    Mahmoud, M. S.; Yabe, T.; Iida, E.

    2017-02-01

    In this work, we present the results of using the diode laser with an energy density of 6.6 × 1011 W/m3 for reducing ZnO to Zn in vacuum as a first step. Subsequently, we use the diode laser for the reduction of MgO using Zn as the reducing agent. Although Zn is one of the candidates proposed for the renewable energy cycle, it is more auspicious to use it as a recyclable reducing agent. Herein, the reduction efficiency was measured in terms of moles of Zn or Mg obtained per moles of ZnO or MgO ablated. The energy efficiency is measured in terms of mass of Zn or Mg produced per energy consumed by diode laser. For the first part, the largest reduction rate was 15.8 mg/s, corresponding to reduction and energy efficiencies of 76.6 pct and 16.14 mg/kJ, respectively. The yield for the process was 8.8 pct of the theoretically calculated one, which is only better than the solar ZnO reduction process. For the second part, the reduction of MgO with Zn was attainable by diode laser, the resultant Mg was associated with Zn traces, and the electron probe micro analysis results showed that the MgO reduction efficiency fluctuates between 14.4 and 26.6 pct. Different scenarios were suggested for the mechanism of the reaction.

  5. Influence of MgO and Hybrid Fiber on the Bonding Strength between Reactive Powder Concrete and Old Concrete

    Directory of Open Access Journals (Sweden)

    Mo Jinchuan

    2016-01-01

    Full Text Available The reactive powder concrete (RPC was used as concrete repair material in this paper. The influence of steel fiber, steel fiber + MgO, and steel fiber + MgO + polypropylene fiber (PPF on the mechanical properties of RPC repair materials and the splitting tensile strength between RPC and old concrete was studied. Influences of steel fiber, MgO, and PPF on the splitting tensile strength were further examined by using scanning electronic microscopy (SEM and drying shrinkage test. Results indicated that the compressive and flexural strength was improved with the increasing of steel fiber volume fraction. However, the bonding strength showed a trend from rise to decline with the increasing of steel fiber volume fraction. Although MgO caused mechanical performance degradation of RPC, it improved bonding strength between RPC and existing concrete. The influence of PPF on the mechanical properties of RPC was not obvious, whereas it further improved bonding strength by significantly reducing the early age shrinkage of RPC. Finally, the relationship of drying shrinkage and splitting tensile strength was studied, and the equation between the splitting tensile strength relative index and logarithm of drying shrinkage was obtained by function fitting.

  6. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    Science.gov (United States)

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  7. Simulation Study on Understanding the Spin Transport in MgO Adsorbed Graphene Based Magnetic Tunnel Junction

    Science.gov (United States)

    Raturi, Ashish; Choudhary, Sudhanshu

    2016-11-01

    First principles calculations of spin-dependent electronic transport properties of magnetic tunnel junction (MTJ) consisting of MgO adsorbed graphene nanosheet sandwiched between two CrO2 half-metallic ferromagnetic (HMF) electrodes is reported. MgO adsorption on graphene opens bandgap in graphene nanosheet which makes it more suitable for use as a tunnel barrier in MTJs. It was found that MgO adsorption suppresses transmission probabilities for spin-down channel in case of parallel configuration (PC) and also suppresses transmission in antiparallel configuration (APC) for both spin-up and spin-down channel. Tunnel magneto-resistance (TMR) of 100% is obtained at all bias voltages in MgO adsorbed graphene-based MTJ which is higher than that reported in pristine graphene-based MTJ. HMF electrodes were found suitable to achieve perfect spin filtration effect and high TMR. I-V characteristics for both parallel and antiparallel magnetization states of junction are calculated. High TMR suggests its usefulness in spin valves and other spintronics-based applications.

  8. Growth, structure and magnetic properties of FePt nanostructures on NaCl(001) and MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Liscio, F; Maret, M; Doisneau-Cottignies, B [Science et Ingenierie des Materiaux et Procedes (SIMaP), INP-Grenoble/CNRS/UJF, BP 75, 38402 Saint-Martin d' Heres (France); Makarov, D; Albrecht, M [Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Roussel, H, E-mail: mireille.maret@simap.grenoble-inp.fr [Consortium des Moyens Technologiques Communs, INP-Grenoble, BP 75, 38402 Saint-Martin d' Heres (France)

    2010-02-10

    A comparison of the structural and magnetic properties of FePt nanostructures grown at different temperatures on NaCl(001) and MgO(001) substrates is presented. A strong influence of the deposition temperature on the epitaxial growth as well as on the size distribution of FePt nanostructures grown on NaCl substrates is observed. In spite of a large lattice mismatch between FePt and NaCl, a 'cube-over-cube' growth of nanostructures with a narrow size distribution was achieved at 520 K. Moreover, the growth of FePt nanostructures on NaCl(001) is not preceded by the formation of a wetting layer as observed on MgO(001). The higher degree of L1{sub 0} chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L1{sub 0} variants with an in-plane tetragonal c-axis indicates that the tensile epitaxial stress induced by the MgO substrate is a key factor in the formation of the L1{sub 0} phase with an out-of-plane c-axis. Superparamagnetic behavior is revealed for the FePt nanostructures grown on NaCl(001) due to their small size and relatively poor chemical order.

  9. Growth, structure and magnetic properties of FePt nanostructures on NaCl(001) and MgO(001)

    Science.gov (United States)

    Liscio, F.; Makarov, D.; Maret, M.; Doisneau-Cottignies, B.; Roussel, H.; Albrecht, M.

    2010-02-01

    A comparison of the structural and magnetic properties of FePt nanostructures grown at different temperatures on NaCl(001) and MgO(001) substrates is presented. A strong influence of the deposition temperature on the epitaxial growth as well as on the size distribution of FePt nanostructures grown on NaCl substrates is observed. In spite of a large lattice mismatch between FePt and NaCl, a 'cube-over-cube' growth of nanostructures with a narrow size distribution was achieved at 520 K. Moreover, the growth of FePt nanostructures on NaCl(001) is not preceded by the formation of a wetting layer as observed on MgO(001). The higher degree of L10 chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L10 variants with an in-plane tetragonal c-axis indicates that the tensile epitaxial stress induced by the MgO substrate is a key factor in the formation of the L10 phase with an out-of-plane c-axis. Superparamagnetic behavior is revealed for the FePt nanostructures grown on NaCl(001) due to their small size and relatively poor chemical order.

  10. Effect of MgO additive on the high-frequency properties of Z-type hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Jia Lijun, E-mail: jlj@uestc.edu.c [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang Huaiwu; Luo Jun; Liu Yingli; Wen Qiye [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2010-07-15

    MgO was introduced into low-temperature sintered Z-type hexaferrites in order to improve their high-frequency electromagnetic properties. In the doped samples the major Z-type phase coexists with a small amount of W-type magnetoplumbite phase. The addition of MgO causes a decrease of the average grain size and an increase of the magnetocrystalline anisotropy (K{sub 1}) and the saturation magnetization (M{sub s}) with the increment of K{sub 1} being larger than that of M{sub s}. These factors result in a reduce of the initial permeability. Also, the samples with MgO additive exhibit higher Q-factor and dc resistivity. Furthermore, the introduction of MgO can decrease the dielectric constant and improve the dielectric loss tangent of the samples by reducing the electronic transition in octahedral site (B-site) between Fe{sup 2+} and Fe{sup 3+} ions.

  11. Methylglyoxal (MGO) inhibits proliferation and induces cell death of human glioblastoma multiforme T98G and U87MG cells.

    Science.gov (United States)

    Paul-Samojedny, Monika; Łasut, Barbara; Pudełko, Adam; Fila-Daniłow, Anna; Kowalczyk, Małgorzata; Suchanek-Raif, Renata; Zieliński, Michał; Borkowska, Paulina; Kowalski, Jan

    2016-05-01

    Glioblastoma multiforme (GBM) is the most malignant and invasive human brain tumor and it is characterized by a poor prognosis and short survival time. Current treatment strategies for GBM using surgery, chemotherapy and/or radiotherapy are ineffective. Thus new therapeutic strategies to target GBM are urgently needed. The effect of methylglyoxal (MGO) on the cell cycle, cell death and proliferation of human GBM cells was investigated. The T98G and U87MG cell lines were cultured in modified EMEM supplemented with 10% fetal bovine serum and maintained at 37°C in a humidified atmosphere of 5% CO2 in air. Cells were exposed to methylglyoxal (0.025mM) per 72h. The influence of MGO on T98G and U87MG cell cycle, proliferation and apoptosis was evaluated as well. Cell cycle phase distribution, proliferation, apoptosis were analyzed by flow cytometry. MGO causes changes in cell cycle and induces accumulation of G1/G0-phase cells and reduced fraction of cells in S and G2/M phases. We have also observed inhibition of cell proliferation and induction of apoptosis in cancer cells. We have also revealed that MGO induces senescence of U87MG but not T98G cells, but further studies are necessary in order to clarify and check mechanism of action of methylglyoxal and it Is a positive phenomenon for the treatment of GBM.

  12. Growth of thin films of TiN on MgO(100) monitored by high-pressure RHEED

    DEFF Research Database (Denmark)

    Pryds, Nini; Cockburn, D.; Rodrigo, Katarzyna Agnieszka;

    2008-01-01

    Reflection high-energy electron diffraction (RHEED) operated at high pressure has been used to monitor the initial growth of titanium nitride (TiN) thin films on single-crystal (100) MgO substrates by pulsed laser deposition (PLD). This is the first RHEED study where the growth of TiN films...

  13. Interaction of free-base tetraphenylporphyrin with magnesium oxide: Influence of MgO morphology on metalation.

    Science.gov (United States)

    Di Filippo, Gianluca; Classen, Andrej; Pöschel, Rebecca; Fauster, Thomas

    2017-02-14

    Using x-ray photoemission spectroscopy, we investigated the self-metalation of free-base tetraphenylporphyrin (2HTPP) on thin MgO(100) films on Ag(100). The deposition of one monolayer 2HTPP on MgO results in the formation of magnesium(ii) tetraphenylporphyrin (MgTPP) at room temperature. We demonstrate that the efficiency of the reaction drastically depends on the morphology of the oxide layers. The latter is changed by varying the substrate temperature during the oxide growth. We observe the complete metalation of the 2HTPP monolayer when the MgO films are grown at 393 K. The increase of the growth temperature to 573 K leads to the reduction of the percentage of metalated molecules to ∼50%. We ascribe these results to the fact that MgTPP formation takes place through the hydroxilation of steps and defects on the MgO surface, which leads to an increase of the OH component in the O 1s line.

  14. Novel Approach for the Reduction of ZnO and MgO Using a Direct Diode-Laser

    Science.gov (United States)

    Mahmoud, M. S.; Yabe, T.; Iida, E.

    2016-10-01

    In this work, we present the results of using the diode laser with an energy density of 6.6 × 1011 W/m3 for reducing ZnO to Zn in vacuum as a first step. Subsequently, we use the diode laser for the reduction of MgO using Zn as the reducing agent. Although Zn is one of the candidates proposed for the renewable energy cycle, it is more auspicious to use it as a recyclable reducing agent. Herein, the reduction efficiency was measured in terms of moles of Zn or Mg obtained per moles of ZnO or MgO ablated. The energy efficiency is measured in terms of mass of Zn or Mg produced per energy consumed by diode laser. For the first part, the largest reduction rate was 15.8 mg/s, corresponding to reduction and energy efficiencies of 76.6 pct and 16.14 mg/kJ, respectively. The yield for the process was 8.8 pct of the theoretically calculated one, which is only better than the solar ZnO reduction process. For the second part, the reduction of MgO with Zn was attainable by diode laser, the resultant Mg was associated with Zn traces, and the electron probe micro analysis results showed that the MgO reduction efficiency fluctuates between 14.4 and 26.6 pct. Different scenarios were suggested for the mechanism of the reaction.

  15. Trapping-desorption and direct-inelastic scattering of HCl from MgO(100)

    Science.gov (United States)

    Korolik, M.; Arnold, D. W.; Johnson, M. J.; Suchan, M. M.; Reisler, H.; Wittig, C.

    1998-02-01

    A molecular beam of hyperthermal HCl ( J=0) impinges on a MgO(100) surface and the scattered HCl is probed state-selectively by using multiphoton ionization. Two regimes are identified. At incident energies of 0.54 and 0.90 eV, scattering is predominantly direct-inelastic, whereas at an incident energy of 0.11 eV, HCl is predominantly trapped and subsequently desorbs. For example, at 0.11 eV, the angular distribution of the HCl product is cosine-like, whereas at 0.54 and 0.90 eV, the scattered HCl is observed to peak near the specular angle.

  16. Radiation Damage and Recovery in Neutron-Irradiated MgO Crystal

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    MgO single crystal was irradiated by neutron up to a dose of 5.74×1018 cm-2. The radiation damage and its recovery were studied by means of UV-VIS and EM spectroscopy. The results indicate that the irradiation generates large amount of optically detectable defects such as single anion vacancies (F+ center), anion divacancies (F2) and some higher order defects. Through isochronal annealing, these defects started a series of processes of diminishing and transforming, and finally all disappeared while annealing at 900 ℃. It seems that the absorption bands of 573 nm are resulted from a higher order and more complex aggregated center than that of 424, 451 nm bands.

  17. Polar catastrophe at the MgO(100)/SnO2(110) interface

    KAUST Repository

    Albar, Arwa

    2016-11-14

    First principles calculations, based on density functional theory, are used to investigate the structural and electronic properties of the epitaxial MgO(100)/SnO2(110) interface of wide band gap insulators. Depending on the interface termination, nonmagnetic metallic and half-metallic interface states are observed. The formation of these states is explained by a polar catastrophe model for nonpolar-polar interfaces. Strong lattice distortions and buckling develop in SnO2, which influence the interface properties as the charge discontinuity is partially screened. Already a single unit cell of SnO2 is sufficient to drive the polar catastrophe scenario. © 2016 The Royal Society of Chemistry.

  18. Smelting reduction of MgO in molten slag by liquid ferrosilicon

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Q.; Gao, J.; Chen, X.; Wei, X.

    2016-10-01

    The smelting reduction of magnesium oxide was researched in this paper. The effect of molten slag composition and reduction temperature on percent reduction of magnesium oxide were discussed, and kinetics of smelting reduction of magnesium oxide in molten slag was studied. The results showed that the reduction extent of magnesium oxide increased by increasing either one of the following factors: the initial mass ratio of Al{sub 2}O{sub 3}/SiO{sub 2}, the addition of CaF{sub 2}, the initial molar ratio of Si/2MgO, and reaction temperature. The overall smelting reduction was controlled by mass transfer in slag with an apparent activation energy 586 kJ mol{sup -}1. (Author)

  19. Structure and electromagnetic properties of FeSiAl particles coated by MgO

    Science.gov (United States)

    Zhang, Yu; Zhou, Ting-dong

    2017-03-01

    FeSiAl particles with a layer of MgO surface coating have excellent soft magnetic and electromagnetic properties. In order to obtain the FeSiAl/MgO composites, Mg(OH)2 sol prepared by sol-gel process was well-mixed with FeSiAl flake particles, and then treated by calcination at 823 K in vacuum. The microstructural, morphological and electromagnetic parameters of FeSiAl/MgO particles were tested. Accordingly, the electromagnetic wave reflection loss in the frequency range of 0.5-18 GHz was calculated. The results show that the surface coating increases coercivity Hc and decreases complex permittivity, leading to a good impedance matching. When the coating amount was 7.5%, reflection loss of the composite particles can reach to -33 dB.

  20. Preparation of nanometer MgO by sol-gel auto-combustion

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nanometer MgO was prepared via a sol-gel auto-combustion technique using magnesium nitrate as raw material and citric acid as chelating agent.IR spectra of the dried gel were used to investigate the structure of the precursors.By studying the different TG curves of magnesium citrate gel prepared by different methods,we found that a combustion process occurred and the nitrate ions acted as an oxidant in the combustion process.TEM photographs of synthesized powders from the sol-gel auto-combustion showed that the crystallites were uniform in size.In addition,the XRD pattern of this sample showed that the particle size was 8.9 nm.The BET curves,in turn,showed that the specific surface of the sample was 26.34 m2/g.The mechanism of the frothing process in restraining agglomeration is discussed.

  1. Simulations of Kikuchi patterns due to thermal diffuse scattering on MgO crystals.

    Science.gov (United States)

    Omoto, Kazuya; Tsuda, Kenji; Tanaka, Michiyoshi

    2002-01-01

    Inelastic scattering of fast transmission electrons from a perfect crystal is investigated using the Bloch wave theory. A comprehensive expression for the scattering of electrons is given, which includes both elastic and inelastic multiple scatterings. This expression is an extended form of Fujimoto's expression for elastic scattering (J. Phys. Soc. Japan 14:1558 (1959)). For the approximation of single inelastic scattering, the expression becomes equivalent to the formula of Rez et al. (Phil. Mag. 35: 81 (1977)). When thermal diffuse scattering (TDS) is considered using the Einstein model or the scattering factor for TDS given by Hall and Hirsch (Proc. R. Soc. A 286: 158 (1965)), Rossouw and Bursill's expression (Acta Cryst. A 41: 320 (1985)) is derived. This expression has been used in computer simulations of TDS intensity distribution (Kikuchi pattern). It is shown that the simulations for magnesium oxide (MgO) using 357 beams agree quite well with the experimental ones.

  2. In vitro reactivity of Na2O MgO SiO2 glasses

    Science.gov (United States)

    Roy, Debdas

    2007-12-01

    A variety of bioactive glasses have been investigated over the last two decades as substitute material for diseased or damaged tissues in a human body. In this investigation, three different melt derived bioactive glasses, each having 55% by mole SiO2 and ratio of MgO to Na2O varying from 1:8 to 8:1, were prepared by melting various oxides at temperature >1250 °C. After microstructure evolution, vitro reactivity of these glasses was examined by keeping them in simulated body fluid (trans buffered pH 7.25 at 25 cc). The surface reactivity of these glasses gradually increased with increasing Na2O/MgO ratio.

  3. On the low-lying states of MgO. II

    Science.gov (United States)

    Bauschlicher, C. W., Jr.; Lengsfield, B. H., III; Silver, D. M.; Yarkony, D. R.

    1981-01-01

    Using a double zeta plus polarization basis set of Slater orbitals, full valence MCSCF (FVMCSCF) calculations were performed for the low-lying states of MgO. For each state the FVMCSCF calculations were used to identify the important configurations which are then used in the MCSCF calculation and subsequently as references in a single and double excitation CI calculation. This approach is found to treat all states equivalently, with the maximum error in the computed transition energies and equilibrium bond lengths of 800/cm and approximately 0.03 A, respectively. The b 3 Sigma + state which has yet to be characterized experimentally is predicted to have a transition energy of approximately 8300/cm and a bond length of 1.79 A. A spectroscopic analysis of the potential curves indicates that their shapes are in quite reasonable agreement with the range of experimental results.

  4. Elemental moment variation of bcc FexMn1-x on MgO(001)

    Science.gov (United States)

    Bhatkar, H.; Snow, R. J.; Arenholz, E.; Idzerda, Y. U.

    2017-02-01

    We report the growth, structural characterization, and electronic structure evolution of epitaxially grown bcc FexMn1-x on MgO(001). It is observed that the 20 nm thick FexMn1-x alloy films remained bcc from 0.65≤x≤1, much beyond the bulk stability range of 0.88≤x≤1. X-ray absorption spectroscopy and X-ray magnetic circular dichroism show that both the Fe and Mn L3 binding energies slightly increase with Mn incorporation and that the elemental moment of Fe in the 20 nm crystalline bcc alloy film remain nearly constant, then shows a dramatic collapse near x 0.84. The Mn MCD intensity is found to be small at all compositions that exhibit ferromagnetism

  5. Sonocatalyzed decolorization of synthetic textile wastewater using sonochemically synthesized MgO nanostructures.

    Science.gov (United States)

    Darvishi Cheshmeh Soltani, Reza; Safari, Mahdi; Mashayekhi, Masumeh

    2016-05-01

    The present study focused on the synthesis of nanostructured MgO via sonochemical method and its application as sonocatalyst for the decolorization of Basic Red 46 (BR46) dye under ultrasonic irradiation. The sonocatalyst was characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray microanalysis (EDX). In the following, the sonocatalytic removal of the dye under different operational conditions was evaluated kinetically on the basis of pseudo first-order kinetic model. The reaction rate of sonocatalyzed decolorization using MgO nanostructures (12.7 × 10(-3) min(-1)) was more efficient than that of ultrasound alone (2.0 × 10(-3) min(-1)). The increased sonocatalyst dosage showed better sonocatalytic activity but the application of excessive dosage should be avoided. The presence of periodate ions substantially increased the decolorization rate from 14.76 × 10(-3) to 33.4 × 10(-3) min(-1). Although the application of aeration favored the decolorization rate (17.8 × 10(-3) min(-1)), the addition of hydrogen peroxide resulted in a considerable decrease in the decolorization rate (9.5 × 10(-3) min(-1)) due to its scavenging effects at specific concentrations. Unlike alcoholic compounds, the addition of phenol had an insignificant scavenging effect on the sonocatalysis. A mineralization rate of 7.4 × 10(-3) min(-1) was obtained within 120 min. The intermediate byproducts were also detected using GC-MS analysis.

  6. Four-fold magnetic anisotropy in a Co film on MgO(0 0 1)

    Energy Technology Data Exchange (ETDEWEB)

    Pires, M.J.M., E-mail: manoeljmp@gmail.co [Servico de Nanotecnologia, Centro de Desenvolvimento da Tecnologia Nuclear, 31270-901 Belo Horizonte, MG (Brazil); Cotta, A.A.C.; Martins, M.D.; Silva, A.M.A.; Macedo, W.A.A. [Servico de Nanotecnologia, Centro de Desenvolvimento da Tecnologia Nuclear, 31270-901 Belo Horizonte, MG (Brazil)

    2011-03-15

    The development of devices based on magnetic tunnel junctions has raised new interests on the structural and magnetic properties of the interface Co/MgO. In this context, we have grown ultrathin Co films ({<=}30 A) by molecular-beam epitaxy on MgO(0 0 1) substrates kept at different temperatures (T{sub S}). Their structural and magnetic properties were correlated and discussed in the context of distinct magnetic anisotropies for Co phases reported in the literature. The sample characterization has been done by reflection high energy electron diffraction, magneto-optical Kerr effect and ferromagnetic resonance. The main focus of the work is on a sample deposited at T{sub S}=25 {sup o}C, as its particular way of growth has enabled a bct Co structure to settle on the substrate, where it is not normally obtained without specific seed layers. This sample presented the best crystallinity, softer magnetic properties and a four-fold in-plane magnetic anisotropy with Co<1 1 0> easy directions. Concerning the samples prepared at T{sub S}=200 and 500{sup o} C, they show fcc and polycrystalline structures, respectively and more intricate magnetic anisotropy patterns. - Research highlights: > Results suggest the lattice is already after the Bain transformation for T{sub S}=25 {sup o}C, and the Co film has a bct structure instead of an fct one. > For deposition temperature of T{sub S}=25 {sup o}C, a four-fold in-plane magnetic anisotropy with Co<1 1 0> easy directions has been obtained. > The growth mode of Co on MgO single crystals at different temperatures resulted in bct Co at T{sub S}=25 {sup o}C, fcc Co at T{sub S}=200 {sup o}C and polycrystalline Co at T{sub S}=500 {sup o}C.

  7. Smelting reduction of MgO in molten slag by liquid ferrosilicon

    Directory of Open Access Journals (Sweden)

    Tang, Qifeng

    2016-06-01

    Full Text Available The smelting reduction of magnesium oxide was researched in this paper. The effect of molten slag composition and reduction temperature on percent reduction of magnesium oxide were discussed, and kinetics of smelting reduction of magnesium oxide in molten slag was studied. The results showed that the reduction extent of magnesium oxide increased by increasing either one of the following factors: the initial mass ratio of Al2O3/SiO2, the addition of CaF2, the initial molar ratio of Si/2MgO, and reaction temperature. The overall smelting reduction was controlled by mass transfer in slag with an apparent activation energy 586 kJ mol-1.En este trabajo se estudia la reducción de óxido de magnesio. La influencia de la composición de las escorias y de la temperatura de reducción sobre el porcentaje de reducción de óxido de magnesio han sido discutidas, y asimismo se ha estudiado la cinética de la reducción del óxido de magnesio en escorias fundidas. Los resultados muestran que la reducción se incrementa al aumentar alguno de los siguientes factores: la proporción de Al2O3/SiO2, la adición de CaF2, la proporción molar de Si/2MgO y la temperatura de reacción. En general la reducción fue controlada por la transferencia de masa en la escoria con una energía aparente de 586 kJ mol-1.

  8. Evaluation of Grain Growth of Corn and Sorghum under K2O Application and Irrigation According

    Directory of Open Access Journals (Sweden)

    Sayed Alireza Valadabadi

    2009-08-01

    Full Text Available In this experiment, interactive effects of different potassium application and water restrict on graingrowth in Iran. The experimental unit had designed by achieved treatment in factorial on the basis completelyrandomized block design with three replicates. Certain factors including potassium and non-potassiumapplications (0 and 200 kg/ha, certain field crops (corn and sorghum and w ater supply were studied. In thisstudy crops water supply was determined by indicated irrigation conditions by keeping leaf Relative WaterContent (RW C > 95% (non-drought stress condition or irrigation conditions and drought condition by RWC= 60-70%. We noticed, however K fertilizer significantly increased the grain growth rate of plants and althoughthe non-drought stress treatment significantly increased grain growth rate. Whereas K application persist lessdamaging of drought stress result and it enabled plant to significantly grow its grain under the droughtconditions. Our finding may give applicable advice to commercial farmers and agricultural researches formanagement and concern on fertilizer strategy and carefully estim ate soil potassium supply w ithin dry or semidryareas as most challengeable issues of environmental safety.

  9. The Mixed-Alkali Effect on The Resistance of Glass to Water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the composition of float glass, the resistance of glass to water, in which a small amount of K2O (0—1.0 wt%) was substituted for equivalent amount of Na2O, was investigated by means of glass grains testing. The components extracted from the glass and total alkalinities in extraction solution were determined by atomic absorption spectroscopy and neutralizing method, respectively. The composition of the glass was 14.4 K2O+Na2O, 4.0MgO, 8.2CaO, 1.4Al2O3, 72.0 SiO2, and the minimum extraction ratio of oxides (maximum durability) occurred at a K2O/Na2O ratio of 0.051(by weight) due to the presence of the mixed-alkali effect. The relative extraction ratio of alkali oxides (R2O) was greater than that of alkaline earth oxides (RO). By means of mixed-alkali effect and lowing relative contents of R2O in the glass, the resistance of float glass to water was improved and its mildew-proof ability was therefore increased.

  10. Влияние содержания MgO на плотность, усадку, сопротивление термическому удару и теплопроводность системы Al[2]O[3] - MgO

    OpenAIRE

    Буякова, Светлана Петровна; Гербер, А. А.

    2015-01-01

    It have been studied properties of the ceramics with different contents MgO. Is studied influence of an additive of MgO on porosity and mechanical properties of composites of Al[2]O[3]-MgO. It was show that the increase in quantity of MgO is followed by increase in volume of a pore space in composites.

  11. Ferromagnetism in IV main group element (C and transition metal (Mn doped MgO: A density functional perspective

    Directory of Open Access Journals (Sweden)

    Vinit Sharma

    2011-09-01

    Full Text Available The formation of magnetic moment due to the dopants with p-orbital (d-orbital is named d0 (d − magnetism, where the ion without (with partially filled d states is found to be responsible for the observed magnetic properties. To study the origin of magnetism at a fundamental electronic level in such materials, as a representative case, we theoretically investigate ferromagnetism in MgO doped with transition metal (Mn and non-metal (C. The generalized gradient approximation based first-principles calculations are used to investigate substitutional doping of metal (Mn and non-metal (C, both with and without the presence of neighboring oxygen vacancy sites. Furthermore, the case of co-doping of (Mn, C in MgO system is also investigated. It is observed that the oxygen vacancies do not play a role in tuning the ferromagnetism in presence of Mn dopants, but have a significant influence on total magnetism of the C doped system. In fact, we find that in MgO the d0 magnetism through C doping is curtailed by pairing of the substitutional dopant with naturally occurring O vacancies. On the other hand, in case of (Mn, C co-doped MgO the strong hybridization between the C (2p and the Mn(3d states suggests that co-doping is a promising approach to enhance the ferromagnetic coupling between the nearest-neighboring dopant and host atoms. Therefore, (Mn,C co-doped MgO is expected to be a ferromagnetic semiconductor with long ranged ferromagnetism and high Curie temperature.

  12. Preserved Collateral Blood Flow in the Endovascular M2CAO Model Allows for Clinically Relevant Profiling of Injury Progression in Acute Ischemic Stroke

    Science.gov (United States)

    Little, Philip; Kvist, Ola; Grankvist, Rikard; Jonsson, Stefan; Damberg, Peter; Söderman, Michael; Arnberg, Fabian; Holmin, Staffan

    2017-01-01

    Interventional treatment regimens have increased the demand for accurate understanding of the progression of injury in acute ischemic stroke. However, conventional animal models severely inhibit collateral blood flow and mimic the malignant infarction profile not suitable for treatment. The aim of this study was to provide a clinically relevant profile of the emergence and course of ischemic injury in cases suitable for acute intervention, and was achieved by employing a M2 occlusion model (M2CAO) that more accurately simulates middle cerebral artery (MCA) occlusion in humans. Twenty-five Sprague-Dawley rats were subjected to Short (90 min), Intermediate (180 min) or Extended (600 min) transient M2CAO and examined longitudinally with interleaved diffusion-, T2- and arterial spin labeling perfusion-weighted magnetic resonance imaging before and after reperfusion. We identified a rapid emergence of cytotoxic edema within tissue regions undergoing infarction, progressing in several distinct phases in the form of subsequent moderation and then reversal at 230 min (p < 0.0001). We identified also the early emergence of vasogenic edema, which increased consistently before and after reperfusion (p < 0.0001). The perfusion of the penumbra correlated more strongly to the perfusion of adjacent tissue regions than did the perfusion of regions undergoing infarction (p = 0.0088). This was interpreted as an effect of preserved collateral blood flow during M2CAO. Accordingly, we observed only limited recruitment of penumbra regions to the infarction core. However, a gradual increase in infarction size was still occurring as late as 10 hours after M2CAO. Our results indicate that patients suffering MCA branch occlusion stand to benefit from interventional therapy for an extended time period after the emergence of ischemic injury. PMID:28068417

  13. 《救荒本草》在日本的传承%Academic heritage of Jiu huang ben cao (Materia Medica for Relief of Famines) in Japan

    Institute of Scientific and Technical Information of China (English)

    何慧玲; 肖永芝

    2014-01-01

    《救荒本草》是中国历史上第1部救荒类本草专著,开创了可食用植物研究的新领域.该书大约在17世纪中后叶传入日本,受到日本著名本草学家的重视,不同传本系统的版本都在日本流传.其后,一些日本名家先后从传到日本的《农政全书》中析出《救荒本草》的内容单独校刻刊行,使《救荒本草》在日本得以更广泛地流传.%Jiu huang ben cao (Materia Medica for Relief of Famines) was the first monograph on famines herbal in the history of China,which creates a new research field of edible plants.Around the middle and late 17th century,Jiu huang ben cao was spread to Japan and aroused great attention of famous Japanese herbalists.Thus,all versions of different edition systems were circulated in Japan.Later,some famous Japanese scholar ssuccessively quoted texts of Jiu huang ben cao from the Nong zheng quan shu (Whole book on Agricultural Administration) spread in Japan,and block-printed it as an independent work.As a result,Jiu huang ben cao virtually circulated widcly in Japan.

  14. A density functional theory study of the adsorption of Hg and HgCl2 on a CaO(001) surface

    Institute of Scientific and Technical Information of China (English)

    GUO Xin; ZHENG Chuguang; LU Nanxia

    2007-01-01

    The adsorption of mercury and mercury chloride on a CaO(001) surface was investigated by the density functional theory (DFT) by using Ca9O9 cluster embedded in an electrostatic field represented by 178 point charges at the crystal CaO lattice positions.For the mercury molecular axis normal to the surface,the mercury can only coordinate to the O2- anion and has a very weak binding energy of 19.649 kJ/mol.When the mercury chloride molecular axis is vertical to the surface,the Cl atom coordinates to the Ca2+ cation and has a binding energy of 23.699 kJ/mol.When the mercury chloride molecular axis is parallel to the surface,the Hg atom coordinates to the O2- anion and has a binding energy of 87.829 kJ/mol,which means that the parallel geometry is more stable than the vertical one.The present calculations show that CaO injection could substantially reduce gaseous mercury chloride,but have no apparent effect on the mercury,which is compatible with the available experimental results.This research will provide valuable information for optimizing and selecting a sorbent for the trace element in flue gas.

  15. Polyethylene Nanocomposites for the Next Generation of Ultralow-Transmission-Loss HVDC Cables: Insulation Containing Moisture-Resistant MgO Nanoparticles.

    Science.gov (United States)

    Pourrahimi, Amir Masoud; Pallon, Love K H; Liu, Dongming; Hoang, Tuan Anh; Gubanski, Stanislaw; Hedenqvist, Mikael S; Olsson, Richard T; Gedde, Ulf W

    2016-06-15

    The use of MgO nanoparticles in polyethylene for cable insulation has attracted considerable interest, although in humid media the surface regions of the nanoparticles undergo a conversion to a hydroxide phase. A facile method to obtain MgO nanoparticles with a large surface area and remarkable inertness to humidity is presented. The method involves (a) low temperature (400 °C) thermal decomposition of Mg(OH)2, (b) a silicone oxide coating to conceal the nanoparticles and prevent interparticle sintering upon exposure to high temperatures, and (c) heat treatment at 1000 °C. The formation of the hydroxide phase on these silicone oxide-coated MgO nanoparticles after extended exposure to humid air was assessed by thermogravimetry, infrared spectroscopy, and X-ray diffraction. The nanoparticles showed essentially no sign of any hydroxide phase compared to particles prepared by the conventional single-step thermal decomposition of Mg(OH)2. The moisture-resistant MgO nanoparticles showed improved dispersion and interfacial adhesion in the LDPE matrix with smaller nanosized particle clusters compared with conventionally prepared MgO. The addition of 1 wt % moisture-resistant MgO nanoparticles was sufficient to decrease the conductivity of polyethylene 30 times. The reduction in conductivity is discussed in terms of defect concentration on the surface of the moisture-resistant MgO nanoparticles at the polymer/nanoparticle interface.

  16. Characterization of the MgO nano powder synthesized by using a liquid phase precursor method for plasma display panels protecting layer.

    Science.gov (United States)

    Jungo, C H; Lee, J Y; Yoon, D H

    2012-02-01

    The characterization of MgO nano powders that were synthesized using a conventional firing liquid phase precursor, rapid firing liquid phase precursor and rapid cooling firing liquid phase precursor were investigated as a function of the heating and cooling rates and the concentration of the impregnated Mg(NO3)2 x 6H2O solution from 1 to 20%. The relative intensity of diffraction peak in the MgO nano powder increased with increasing firing temperature from 800 to 1200 degrees C, indicating a higher crystalline MgO nano powder. In addition, the relative intensities of the MgO nano powder synthesized at the designated temperature showed similar behavior regardless of the impregnated Mg(NO3)2 x 6H2O solution concentration from the XRD analysis. The field emission scanning electron microscope and high resolution transmission electron microscope analysis showed that the size and shape of the MgO nano powder can be controlled by the temperature, the firing and cooling processes, and the impregnated Mg(NO3)2 x 6H2O solution concentration. Moreover, the CL spectra of the synthesized MgO nano powders showed a higher luminance efficiency than commercial MgO nano powder.

  17. Synthesis of Ni supported by CaO from Ni(0)L complexes (L=dihydrazine, bisethylenediamine)

    Science.gov (United States)

    Perangin-angin, Sabarmin; Bangun, Nimpan; Ginting, Adil; Putri, Nabila Karina

    2017-01-01

    Ni/CaO have been synthesis by using thermal reaction between Ni(0)L complexes (L=dihydrazine, bisethylenediamine) and CaO from Ca-stearate or CaCO3. Ni(0)L complexes (L=dihydrazine, bisethylenediamine) prepared by ligand substitution between Cl and hydrazine to perform dichlorohydrazine-Nickel (II) and this reaction monitored by IR spectroscopy and then mention as A. Two ways reaction have been used due to obtain dihydrazine-Nickel (0) from dichlorohydrazine-Nickel (II). The resulted dihydrazine-Nickel (0), B and E, then analyzed by FT-IR. To compare the result, dichloroethylenediamine-Nickel (II), as C, also has been prepared by ligand substitution between Cl and ethylenediamine. The obtain dichloroethylenediaminedichloro-Nickel (II) was then further reduction by using Zinc dust then analyzed by IR spectroscopy and result bisethylenediamine-Nickel (0), as D. The N-H functional groups have been indicated at 3500 - 3000 cm -1 for all A-E. Ni(0)L that obtain then characterized by SEM-EDX to confirm the morphology and molecules that contain in Ni(0)L that form. The reaction between Ca-stearate and dihydrazine-Nickel (0) then resulted black that mention as F. While the reaction between CaCO3 and Ni(0)L respectively resulted Ni/CaO, G, H and I. Ni/CaO surface then characterized by XRD, SEM-EDX and surface area analysis. The EDX analysis confirm the forming compounds of Ni/CaO. All of G, H and I are mesoporous materials.

  18. Heat recovery from a thermal energy storage based on the Ca(OH){sub 2}/CaO cycle

    Energy Technology Data Exchange (ETDEWEB)

    Azpiazu, M.N. [E.T.S. Ingenieros, Bilbao (Spain). Dpto. de Ingenieria Quimica y del Medio Ambiente; Morquillas, J.M. [E.T.S. Ingenieros, Bilbao (Spain). Dpto. de Maquinas y Motores Termicos; Vazquez, A. [E.S. da Marina Civil, La Coruna (Spain). Dpto. de Energia y Propulsion Maritima

    2003-04-01

    Thermal energy storage is very important in many applications related to the use of waste heat from industrial processes, renewable energies or from other sources. Thermochemical storage is very interesting for long-term storage as it can be carried out at room temperature with no energy losses. Dehydration/hydration cycle of Ca(OH){sub 2}/CaO has been applied for thermal energy storage in two types of reactors. One of them was a prototype designed by the authors, and in the other type conventional laboratory glassware was used. Parameters such as specific heats, reaction rate and enthalpy, mass losses and heat release were monitored during cycles. Although in the hydration step water is normally added in vapour phase, liquid water, at 0{sup o}C has been used in these experiences. Results indicated that the energy storage system performance showed no significant differences, when we compared several hydration/dehydration cycles. The selected chemical reaction did not exhibit a complete reversibility because complete Ca(OH){sub 2} dehydration, was not achieved. However the system could be used satisfactorily along 20 cycles at least. Heat recovery experiments showed general system behaviour during the hydration step in both types of reactors. The designed prototype was more efficient in this step. Main conclusions suggested carrying out one complete cycle at a higher dehydration temperature to recover total system reversibility. A modification of the prototype design trying to enhance heat transfer from the Ca(OH){sub 2} bed could also be proposed. (author)

  19. Caos determinístico em um modelo simplificado de cadeia produtiva Deterministic chaos in simplified supply chain model

    Directory of Open Access Journals (Sweden)

    Júlio César Bastos de Figueiredo

    2013-06-01

    Full Text Available Este trabalho tem por objetivo apresentar um modelo teórico simplificado de cadeia produtiva onde as relações entre o número de competidores, os tempos de resposta para ajustes da produção e a intensidade da resposta das empresas levam intrinsecamente ao surgimento de oscilações caóticas na oferta e na demanda. No modelo proposto, desenvolvido com o uso da metodologia de dinâmica de sistemas, as flutuações irregulares na demanda e nos preços estão intimamente relacionadas com a própria estrutura da cadeia, ou seja, com suas regras, políticas e capacidades produtivas. São feitas considerações sobre a importância do estudo de caos aplicado à economia e são discutidas técnicas para caracterização de comportamento caótico em séries econômicas.The purpose of this study was to present a simplified supply chain model where the relations between the number of competitors, the delay in production adjustments, and the intensity response of each company lead, intrinsically, to the emergence of chaotic oscillations in supply and demand. In the considered model, developed with the use of the System Dynamics methodology, the irregular fluctuations in demand and prices are closely related to the supply chain structure, that is, its rules, policies and capabilities. Discussions about the importance of the study of chaos applied to the economy are developed and specific techniques for characterization of chaotic behavior in economic time series are presented.

  20. Mapping the geographic distribution of canopy species communities in lowland Amazon rainforest with CAO-AToMS (Invited)

    Science.gov (United States)

    Feret, J.; Asner, G. P.

    2013-12-01

    Mapping regional canopy diversity will greatly advance our understanding as well as the conservation of tropical rainforests. Changes in species composition across space and time are particularly important to understand the influence of climate, human activity and environmental factors on these ecosystems, but to date such monitoring is extremely challenging and is facing a scale gap between small-scale, highly detailed field studies and large-scale, low-resolution satellite observations. Advances were recently made in the field of spectroscopic imagery for the estimation of canopy alpha-diversity, and an original approach based on the segmentation of the spectral space proved its ability to estimate Shannon diversity index with unprecedented accuracy. We adapted this method in order to estimate spectral dissimilarity across landscape as a proxy for changes in species composition. We applied this approach and mapped species composition over four sites located in lowland rainforest of Peruvian Amazon. This study was based on spectroscopic imagery acquired using the Carnegie Airborne Observatory (CAO) Airborne Taxonomic Mapping System (AToMS), operating a unique sensor combining the fine spectral and spatial resolution required for such task. We obtained accurate estimation of Bray-Curtis distance between pairs of plots, which is the most commonly used metric to estimate dissimilarity in species composition (n=497 pairs, r=0.63). The maps of species composition were then compared to topo-hydrographic properties. Our results indicated a strong shift in species composition and community diversity between floodplain and terra firme terrain conditions as well as a significantly higher diversity of species communities within Amazonian floodplains. These results pave the way for global mapping of tropical canopy diversity at fine geographic resolution.

  1. 成分对 MgO -AI2O3-C 耐火材料抗侵蚀性能的影响%Effects of Composition on Corrosion Resistance of MgO-Al2O3 -C Refractory

    Institute of Scientific and Technical Information of China (English)

    赵树茂; 梅国晖; 张玖; 谢植

    2015-01-01

    The proportion of raw materials has an important influence on corrosion resistance of MgO-Al2 O3-C refractory besides working conditions.MgO-Al2 O3-C samples were prepared with different type of fused magnesia and various amounts of Al2 O3 and graphite.Their corrosion rates in CaO-rich slag were investigated by rotating the samples in the molten slag.The effect of composition on the corrosion resistance of MgO-Al2 O3-C refractory was studied.The results showed that the corrosion resistance decreases as the magnesia's impurity increases.And with the increase of Al2 O3 and graphite content,the corrosion resistance increases firstly and then decreases.Excessive Al2 O3 results in viscosity decrease of slag,and excessive graphite results in porosity increase.Thus,for MgO-Al2 O3-C refractory that used under CaO-rich slag,the ideal Al2 O3 content is 10%~30% and the graphite content is 10%~20%.%除工作环境外,原料配比对 MgO -Al2 O3-C 材料抗侵蚀性能具有重要影响。采用不同杂质含量的电熔镁砂原料,按照不同 C 含量和 Al2 O3含量制备 MgO -Al2 O3-C 试样。通过转动试样浸渣方法测得不同试样在富 CaO 熔渣中的侵蚀速率,从而研究了成分对抗侵蚀性能的影响。结果表明抗侵蚀性能随着镁砂杂质含量的增加而迅速降低,随着碳含量以及 Al2 O3含量的增加而先增加后降低。过多的 Al2 O3导致了熔渣黏度下降,而过多的碳导致了空隙率增大。根据上述结果,在富 CaO 熔渣中 MgO -Al2 O3-C 材料理想的Al2 O3质量分数为10%~30%,理想的 C 质量分数为10%~20%。

  2. Study of the charge kinetics of MgO (1 1 0) subjected to high energy electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Boughariou, A., E-mail: aicha_boughariou@yahoo.fr [LaMaCoP, Université de Sfax pour le sud, Faculté des Sciences, 3038 Sfax Tunisie (Tunisia); Kallel, A. [LaMaCoP, Université de Sfax pour le sud, Faculté des Sciences, 3038 Sfax Tunisie (Tunisia); Blaise, G. [LPS, Université Paris-Sud XI, Batiment 510, Orsay 91405 (France)

    2014-09-15

    Highlights: • Variation of the logarithm of SEE yield with the injected dose in MgO (1 1 0) at high energy. • Critical energy E{sub C} of MgO (1 1 0). • Formation of an electrostatic mirror. • Breakdown phenomenon (current density effect). - Abstract: This article presents a study performed with a dedicated scanning electron microscope (SEM) on the electrical property evolution of magnesium oxide (1 1 0) single crystal during 15 and 30 keV irradiation. First, the charging behavior is studied during the charge injection process at low current density J{sub 0}, by measuring the logarithm of the secondary electron emission yield (lnσ). Next, we have investigated the dependence on the current density of the charge-trapping phenomena in MgO (1 1 0). The results shown that beyond the crossover energy E{sub 2}, the observed effects varies depending on whether the energy of the primary electrons is lower or higher than an energy called critical energy E{sub c} = 20 keV (in the case of MgO (1 1 0)). When irradiating the material at E{sub 0} < E{sub c} and at low J{sub 0}, self regulated regime is obtained, if J{sub 0} is sufficiently intense an aging regime is reached. This latter regime is characterized by a positive surface charge, when a negative charge was expected. At E{sub 0} > E{sub c}, and for low J{sub 0}, the detailed monitoring of the charge kinetic of MgO (1 1 0) at high primary energy E{sub 0} = 30 keV, permit to show that the combined effect of the increased negative surface potential during irradiation and extractor field below the surface of MgO fact that lnσ undergoes a strong slope failure at the beginning of the injection and stabilizes at a value much less than zero leading to the formation of an electrostatic mirror. At high J{sub 0}, the consequences of the charge accumulation are violent and a breakdown phenomenon is observed.

  3. Caos, fluidos y flujos

    Directory of Open Access Journals (Sweden)

    Luis Fernando Herrera Díaz

    2011-02-01

    Full Text Available During the last 30 years, the world of science has been revolutionized with the birth of a new paradigm: this form of seeing the world is known as The Chaos Theory. "In their short life it has already touched all the branches of knowledge, including Engineering" says Mora (1998.1t is so that many of the will known engineers like Aris in the ñeld of the chemical reactors, Froment in heterogeneous catalysis, Coppens who investigates the phenomena's of diffusionreaction in Zeolites, Julio Ottino in the mixing offluids, have begun to improve old outlines through thís theory. The present article seeks for to show the main concepts, in which the theory of chaos is based, through simple examples, showing mainly its relationships with chemical engineering, such as flow and mixing offluids.

  4. Turismo y Caos

    Directory of Open Access Journals (Sweden)

    Carolina Gómez Gómez

    2008-11-01

    Full Text Available “Turismo y caos” es una producción literaria que brinda una reflexión acerca del pensamiento turístico posmoderno, enfocándose principalmente en las teorías de Alberto Sessa, Claude Kaspar, José Miguel Fernán dez Güell y finalmente, la Organización Mundial del Turismo, OMT. Es así como este texto pretende integrar, a través de una visión sistémica, los diferentes elementos que conforman y definen el turismo, dando lugar a un nuevo concepto que fusiona las teorías propuestas a través del tiempo y además la opinión personal de los autores de esta obra.

  5. SrRuO3 thin films grown on MgO substrates at different oxygen partial pressures

    KAUST Repository

    Zou, Bin

    2013-01-08

    A comprehensive study of SrRuO3 thin films growth on (001) MgO substrates by pulsed laser deposition in a wide oxygen pressure range from 10 to 300 mTorr was carried out. The experimental results showed a correlation between the lattice constants, resistivity, and oxygen partial pressures used. Ru deficiency detected only in films deposited at lower oxygen pressures (<50 mTorr), resulted in an elongation of the in-plane and out-of-plane lattice constants and an increase in the film resistivity. When deposited with oxygen partial pressure of 50 mTorr, SrRuO3 films had lattice parameters matching those of bulk SrRuO3 material and exhibited room temperature resistivity of 320 μΩ·cm. The resistivity of SrRuO 3/MgO films decreased with increasing oxygen partial pressure. Copyright © 2013 Materials Research Society.

  6. Fast and accurate approximate quasiparticle band structure calculations of ZnO, CdO, and MgO polymorphs

    Science.gov (United States)

    Ataide, C. A.; Pelá, R. R.; Marques, M.; Teles, L. K.; Furthmüller, J.; Bechstedt, F.

    2017-01-01

    We investigate ZnO, CdO, and MgO oxides crystallizing in rocksalt, wurtzite, and zincblende structures. Whereas in MgO calculations, the conventional LDA-1/2 method is employed through a self-energy potential (VS), the shallow d bands in ZnO and CdO are treated through an increased amplitude (A ) of VS to modulate the self-energy of the d states to place them in the quasiparticle position. The LDA+A -1/2 scheme is applied to calculate band structures and electronic density of states of ZnO and CdO. We compare the results with those of more sophisticated quasiparticle calculations and experiments. We demonstrate that this new LDA+A -1/2 method reaches accuracy comparable to state-of-the-art methods, opening a door to study more complex systems containing shallow core electrons to the prize of LDA studies.

  7. UHV and Ambient Pressure XPS: Potentials for Mg, MgO, and Mg(OH)2 Surface Analysis

    Science.gov (United States)

    Head, Ashley R.; Schnadt, Joachim

    2016-12-01

    The surface sensitivity of x-ray photoelectron spectroscopy (XPS) has positioned the technique as a routine analysis tool for chemical and electronic structure information. Samples ranging from ideal model systems to industrial materials can be analyzed. Instrumentational developments in the past two decades have popularized ambient pressure XPS, with pressures in the tens of mbar now commonplace. Here, we briefly review the technique, including a discussion of developments that allow data collection at higher pressures. We illustrate the information XPS can provide by using examples from the literature, including MgO studies. We hope to illustrate the possibilities of ambient pressure XPS to Mg, MgO, and Mg(OH)2 systems, both in fundamental and applied studies.

  8. Possibility of a 2D SiC monolayer formation on Mg(0001) and MgO(111) substrates

    Science.gov (United States)

    Kuzubov, A. A.; Eliseeva, N. S.; Krasnov, P. O.; Tomilin, F. N.; Fedorov, A. S.; Tolstaya, A. V.

    2013-08-01

    The geometrical characteristics of a 2D SiC monolayer on Mg(0001) and MgO(111) plates regarded as potential materials for growing two-dimensional silicon carbide were studied. The most favorable positions of the atoms of 2D SiC on the substrates were determined. In the 2D SiC/Mg(0001) system, unlike in 2D SiC/MgO(111), the deviation of the carbon atom from the silicon carbide monolayer was insignificant (0.08 Å). Consequently, magnesium can be used as a substrate for growing two-dimensional silicon carbide. The use of MgO(111) is not recommended because of a significant distortion of the 2D SiC surface.

  9. The role of sacrificial fugitives in thermoplastic extrusion feedstocks onproperties of MgO supports for oxygen transport membranes

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Kwok, Kawai; Søgaard, Martin

    2015-01-01

    , sintered at 1300◦C for 2 h, showed a total porosity of 42.5% and gas permeability of 4.7 × 10−16m2. Subsequently, the4-point bending strengths of this substrate, scaled to an effective volume of 10 mm3, were 77 and 60 MPa for room and operation temperature(850◦C). Both, permeation rate and mechanical...... of the pore former on microstructure, gas permeation and the mechanical properties for various sintering temperatures were investigated.The gas permeation behavior of the MgO supports was highly dependent on pore neck size and total open porosity. MgO substrate, with 20% spherical graphite as a pore former...

  10. Novel Oscillation Period of the Interlayer Exchange Coupling in Fe/Cr/Fe Due to MgO Capping

    Science.gov (United States)

    Halley, D.; Bengone, O.; Boukari, S.; Weber, W.

    2009-01-01

    A novel period of the interlayer exchange coupling as a function of Cr thickness is observed in epitaxial Fe/Cr/Fe (001) sandwiches capped with MgO. This additional period, equal to 3 chromium atomic layers, vanishes when the capping is Cr. A strong oscillation of the magnetic coupling is also observed as a function of the thickness of the Fe layer next to the MgO capping layer. This effect is attributed to the formation of quantum well states in this Fe layer. It is believed that this confinement modifies the reflection coefficient at the Cr/Fe interface for electrons of a particular symmetry and leads to the new coupling period which is linked to the Fermi surface topology of chromium.

  11. MgO reflectance data for Monte Carlo simulation of LaBr{sub 3}:Ce scintillation crystals

    Energy Technology Data Exchange (ETDEWEB)

    Scafè, Raffaele, E-mail: raffaele.scafe@uniroma1.it [Dept. of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 324, I-00161 Rome (Italy); Pani, Roberto; Pellegrini, Rosanna; Cinti, Maria Nerina [Dept. of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 324, I-00161 Rome (Italy); Bennati, Paolo [INFN-Roma I, Italian National Institute of Nuclear Physics, Piazzale Aldo Moro 5, I-00185 Rome (Italy); Lo Meo, Sergio [National Institution for Insurance against Accidents at Work, Via Fontana Candida 1, I-00040, Monte Porzio Catone (Italy)

    2013-02-11

    Present paper is aimed to estimate the spectral reflectance of MgO as a function of layer thickness around LaBr{sub 3}:5%Ce crystals. A reference emission spectrum of scintillator was calculated averaging 15 experimental trends from literature. A survey on MgO reflectance provided experimental data in the wavelength region of interest without thickness information, while trends with dimensional facts were found in the adjacent wavelength region. An algorithm was developed for interpolating spectral data in the wavelength region of interest for given thickness. A comparison between reflectors for LaBr{sub 3}:Ce is summarized in Appendix A. Results are presented in form of weighted average values as well as numerical trends suitable, in particular, as input for Monte Carlo simulations of encapsulated crystals.

  12. Phenomenological in-situ TEM gas exposure studies of palladium particles on MgO at room temperature

    Science.gov (United States)

    Heinemann, K.; Poppa, H.; Osaka, T.

    1983-01-01

    It has been found that very small vapor-deposited catalytically active metal particles in the 1-2 nm size range on metal oxide substrates can undergo significant changes when they are exposed to gases such as oxygen or air, or even when allowed to 'anneal' at room temperature (RT) under vacuum conditions. The present investigation is concerned with continued in-situ gas exposures of as-deposited, 1 to 2 nm size palladium particles on MgO to air, oxygen, nitrogen, hydrogen, CO, and water vapor at RT. It is found that the low-pressure exposure to various gases at RT can significantly affect small palladium particles supported on MgO surfaces. Exposure to oxygen for 3 min at 0.0002 m bar produces a considerable amount of coalescence, flattening of the particles, and some distinct crystallographic particle shapes.

  13. Contact induced spin relaxation in graphene spin valves with Al2O3 and MgO tunnel barriers

    Directory of Open Access Journals (Sweden)

    Walid Amamou

    2016-03-01

    Full Text Available We investigate spin relaxation in graphene by systematically comparing the roles of spin absorption, other contact-induced effects (e.g., fringe fields, and bulk spin relaxation for graphene spin valves with MgO barriers, Al2O3 barriers, and transparent contacts. We obtain effective spin lifetimes by fitting the Hanle spin precession data with two models that include or exclude the effect of spin absorption. Results indicate that additional contact-induced spin relaxation other than spin absorption dominates the contact effect. For tunneling contacts, we find reasonable agreement between the two models with median discrepancy of ∼20% for MgO and ∼10% for Al2O3.

  14. Dependency of Tunneling-Magnetoresistance Ratio on Nanoscale Spacer Thickness and Material for Double MgO Based Perpendicular-Magnetic-Tunneling-Junction.

    Science.gov (United States)

    Lee, Du-Yeong; Hong, Song-Hwa; Lee, Seung-Eun; Park, Jea-Gun

    2016-12-08

    It was found that in double MgO based perpendicular magnetic tunneling junction spin-valves ex-situ annealed at 400 °C, the tunneling magnetoresistance ratio was extremely sensitive to the material and thickness of the nanoscale spacer: it peaked at a specific thickness (0.40~0.53 nm), and the TMR ratio for W spacers (~134%) was higher than that for Ta spacers (~98%). This dependency on the spacer material and thickness was associated with the (100) body-centered-cubic crystallinity of the MgO layers: the strain enhanced diffusion length in the MgO layers of W atoms (~1.40 nm) was much shorter than that of Ta atoms (~2.85 nm) and the shorter diffusion length led to the MgO layers having better (100) body-centered-cubic crystallinity.

  15. Manufacture of Bi-cuprate thin films on MgO single crystal substrates by chemical solution deposition

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Bertelsen, Christian Vinther; Andersen, Niels Hessel

    2014-01-01

    Bi2Sr2CaCu2O8 thin films have been deposited on MgO single crystal substrates by spin-coating a solution based on 2-ethylhexanoate precursors dissolved in xylene. Pyrolysis takes place between 200°C and 450°C and is accompanied by the release of 2-ethylhexanoic acid, CO2 and H2O vapour. Highly c...

  16. Structural Properties of Alternate Monatomic Layered [Fe/Co]n Epitaxial Films on MgO Substrate

    Science.gov (United States)

    Chu, In Chang; Saki, Yoshinobu; Kawasaki, Shohei; Doi, Masaaki; Sahashi, Masashi

    2008-06-01

    Body-centered-cubic (bcc) Fe50Co50 material is reported to show a high bulk spin scattering coefficient on current perpendicular to plane-giant magneto-resistance (CPP-GMR) system. But the origin of that phenomenon does not make sure yet. We prepared artificially alternate monatomic layered (AML) [Fe/Co] 41 MLs epitaxial films (Ts: 75, 250 °C) by monatomic deposition method and investigated the topology of AML [Fe/Co]n epitaxial films on MgO substrate with different orientation (001), (011) by the scanning tunnel microscopy (STM) and reflection high energy electron diffraction (RHEED), which we could confirm Frank-van der Merwe (FM) growth mode for AML [Fe/Co]n on MgO(001) and Volmer-Weber (VW) growth mode for that on Mg(011). The roughness of surface, Ra (0.20 nm) of AML [Fe/Co] 41 MLs epitaxial film grown at 75 °C on MgO(001) is smaller than that (0.46 nm) of AML [Fe/Co] grown at 250 °C on MgO(001), which has the large terraces of over 50 nm (Ra: 0.17 nm), even though there are some valleys between large terraces. Moreover we confirmed the structural properties of trilayered epitaxial films with AML [Fe/Co]n (Ra: 0.18 nm) and Fe50Co50 alloy epitaxial film on Au electrode by RHEED before confirming the characteristics of CPP-GMR devices.

  17. Study on the Effect between Dynamics of MgO Grain Growth and Additive of Y2O3

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, samples of CaO-riched MgO-CaO added with Y2O3 were prepared and the growth rate of MgO grains were investigated, and the calculation of the grain growth active energy at different temperatures was done for the high performance anti-hydration CaO-riched MgO-CaO clinker. It is of significance for decreasing the synthetic temperature in industry production.

  18. In situ oxygen conditioning of /001/ MgO thin film substrates for film growth studies by electron microscopy

    Science.gov (United States)

    Moorhead, R. D.; Poppa, H.

    1979-01-01

    It was found that the in situ treatment of 001-plane single-crystal films of MgO (prepared by epitaxial growth from the vapor phase) at high temperatures with a jet of oxygen will produce a surface that is almost equivalent, for epitaxial studies, to surfaces with the same orientation prepared by vacuum cleavage of bulk single crystals. The effectiveness of the process is demonstrated by its impact on the epitaxy of silver.

  19. First-principles calculations of the indigo encapsulation and adsorption by MgO nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Ochoa, F., E-mail: fsanchez@ifuap.buap.mx; Cocoletzi, Gregorio H. [Instituto de Física “Ing. Luis Rivera Terrazas,” Benemérita Universidad Autónoma de Puebla, Av. San Claudio y Blvd. 18 Sur, Col. San Manuel, C.P. 72570 Puebla, Pue (Mexico); Canto, Gabriel I. [Departamento de Materiales y Corrosión, Centro de Investigación en Corrosión, Universidad Autónoma de Campeche, Col. Buenavista, C.P. 24039 San Francisco de Campeche, Campeche (Mexico); Takeuchi, Noboru [Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km 107 Carretera Tijuana-Ensenada, CP. 22800 Ensenada, B.C (Mexico)

    2014-06-07

    We have performed ab-initio calculations to investigate the structural and electronic properties of (m,m) chiral magnesium oxide nanotubes, (m,m)MgONTs, to explore the encapsulation, inclusion, and adsorption of dyes (organic molecules) such as Indigo (IND). Studies start by determining the structural parameters of the MgO nanotubes with different diameters and the IND. The indigo encapsulation into the MgONT is studied considering four (m,m) chiralities which yield 4 different NT diameters. In the endohedral functionalization, the indigo is within the NT at a tilt angle as in previous theoretical studies of organic molecules inside carbon and boron-nitride nanotubes. Results show that the encapsulation is a strong exothermic process with the m = 6 case exhibiting the largest encapsulation energy. It is also explored the indigo adsorption on the NT surface in the parallel and perpendicular configurations. The perpendicular configuration of the IND adsorption on the (8,8)MgONT exhibits the largest energy. The indigo inclusion within the NTs meets a potential barrier when m < 6, however this barrier diminishes as the index increases. Additionally, we have determined the total density of states (DOS), partial DOS, electron charge redistributions, and the highest occupied molecular orbital–lowest unoccupied molecular orbital levels for the NTs with m = 6. Very strong binding energies and electron charge transfer from the IND to NTs is present in the atomic structures.

  20. First principles investigation of magnetocrystalline anisotropy at Full Heusler / MgO interfaces

    Science.gov (United States)

    Vadapoo, Rajasekarakumar; Hallal, Ali; Chshiev, Mairbek

    2014-03-01

    Magnetic tunnel junctions with perpendicular magnetic anisotropy (PMA) have the potential for realizing next generation high density nonvolatile memories and logic devices. The origin of high PMA in these interfaces has been explained by orbital hybridizations at interface along with spin-orbit interactions. Here we present a systematic study of PMA in Heusler alloy [X2YZ]/ MgO interfaces using first principle methods with X =Co, YZ =FeAl, MnGe and MnSi. Among the interfaces studied, we found that Co terminated interface of Co2FeAl/MgO gives rise to PMA value of 1.2erg/cm2 in agreement with recent experimental observations. On the contrary, FeAl terminated interfaces of the same structure shows in-plane magnetic anisotropy (IMA). We also found that the most of PMA contribution originates from dyz and dz2 orbitals of Co atoms at the interface. Finally, Co2MnGe and Co2MnSi structures tend to favor IMA for any termination.

  1. The effect of reinforcement volume ratio on porosity and thermal conductivity in Al-Mgo composites

    Directory of Open Access Journals (Sweden)

    Recep Calin

    2012-12-01

    Full Text Available In this study, the effects of reinforcement volume ratios (RVR on composite structure and thermal conductivity were examined in Al-MgO reinforced metal matrix composites (MMCs of 5%, 10% and 15% RVR produced by melt stirring. In the production of composites, EN AW 1050A aluminum alloy was used as the matrix material and MgO powders with particle size of -105 µm were used as the reinforcement material. For every composite specimen was produced at 500 rev/min stirring speed, at 750 °C liquid matrix temperature and 4 minutes stirring time. Composite samples were cooled under normal atmosphere. Then, microstructures of the samples were determined and evaluated by using Scanning Electron Microscope (SEM and Energy Dispersive X-ray Spectroscopy (EDS analysis. In general, it was observed that the reinforcement exhibited a homogeneous distribution. Furthermore, it was determined that the increase in the RVR increased porosity. From the Scanning Electron Microscope images, a thermal Ansys model was generated to determine effective thermal conductivity. Effective thermal conductivity of Al-MgO composites increased with the decrease in reinforcement volume ratio.

  2. Mgo-Kısmen Stabilize Zirkonya Dental Altyapı Seramiklerin Üretimi Ve Karakterizasyonu

    OpenAIRE

    Yazıcı, Emine Gamze

    2013-01-01

    Dental uygulamalarda kullanılan üç çeşit zirkonyum içeren seramik sistemi mevcuttur. Bunlar, yitriyum tetragonal zirkonya polikristalleri (3Y-TZP), magnezyum kısmen stabilize zirkonya (Mg-KSZ) ve zirkonya ile toklaştırılmış alümina (ZTA) şeklinde sınıflandırılırlar. MgO diğer kararlılaştırıcı oksitlere göre daha ucuz ve bol bulunuduğu için kısmen stabilize edilmiş ZrO2 esaslı seramiklerde en fazla araştırmaya konu olmuş katkıdır. Bu çalışma üç aşamadan oluşmaktadır. Birinci aşamada monoklinik...

  3. Adsorption of Ponceau S from aqueous solution by MgO nanoparticles

    Science.gov (United States)

    Venkatesha, T. G.; Nayaka, Y. Arthoba; Chethana, B. K.

    2013-07-01

    Ponceau S or Acid Red 112 is a widely used dye with versatile applications whose biotransformation products are toxic and is a suspected carcinogen. In the present work, magnesium oxide (MgO) nanoparticles were synthesized by precipitation method and used for the sorption of Ponceau S from aqueous solution. The effects of parameters like contact time, pH and temperature on the adsorption capacity were studied. The adsorption isotherm studies were carried out using Langmuir, Freundlich and Temkin models, of which Langmuir model was found more suitable. Pseudo-second-order model fitted well with good agreement with the experimental values of qe (equilibrium adsorption capacity). The values of thermodynamic parameters like enthalpy (ΔH°) and entropy (ΔS°) were found to be 35.71 kJ/mol and 0.127 J/K/mol, respectively. The negative values of standard free energy (ΔG°) suggested that the adsorption process is spontaneous with the energy of activation equal to 28.58 kJ/mol.

  4. Epitaxial growth of Al-Cr-N thin films on MgO(111)

    Energy Technology Data Exchange (ETDEWEB)

    Willmann, H. [Materials Center Leoben, 8700 Leoben (Austria); IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden)], E-mail: herwi@ifm.liu.se; Beckers, M. [IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden); Birch, J. [IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden)], E-mail: jens.birch@ifm.liu.se; Mayrhofer, P.H.; Mitterer, C. [Department of Physical Metallurgy and Materials Testing, University of Leoben, 8700 Leoben (Austria); Hultman, L. [IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden)

    2008-11-28

    Cubic rock salt structure Al{sub 0.60}Cr{sub 0.40}N and Al{sub 0.68}Cr{sub 0.32}N films of different thicknesses were grown epitaxially onto MgO(111) substrates by reactive unbalanced magnetron sputtering at 500 deg. C . Rutherford backscattering spectroscopy reveals stoichiometric nitrides with Al/Cr ratios close to the ones of the used compound targets of 60/40 and 70/30. High resolution X-ray diffraction proves epitaxial growth over the whole film thickness up to thicknesses of {approx} 1.8 {mu}m. Reciprocal space maps and selected area electron diffraction show that the Al{sub x}Cr{sub 1-x}N films grow fully relaxed. Scanning and transmission electron microscopy imaging reveals columnar microstructures with column widths between 12-16 nm and {l_brace}001{r_brace} surface faceting on individual columns. The fully relaxed growth and the columnar structure can be attributed to limited ad-atom mobility on the initial Al{sub x}Cr{sub 1-x}n (111) growth surface.

  5. Structure of helicoptering H2 molecules on MgO(001)

    Science.gov (United States)

    Jack, David B.; Sadeghifar, Alireza; Livingston, Christina F.; Kootnekoff, Brandon A.; Makins, Caitlyn; Hawrylo, Jennifer; Creelman, J. Brianna; McTaggart, Julie L.

    2015-11-01

    Monte Carlo (MC) simulations of helicoptering (J = 1; mj = ± 1) H2 molecules on the MgO(001) surface using rotationally averaged interaction potentials are reported and show that at the coverage Ө = 0.5 the film forms a structure with c(2 × 2) symmetry in agreement with experiment. This structure is stable up to 6 K. The unit cell is arranged in a quincunx pattern and has a density of two H2 molecules per unit cell. Each molecule sits above the cation sites with its axis of quantization pointing perpendicular to the surface on average. The unit cell symmetry is "c" type in agreement with helium atom scattering experiment and in contrast with the "p" type structures observed in previous simulations which did not include quantum mechanically averaged potentials from the start. The occurrence of defects was also observed with increasing frequency as the temperature rose. An increase in the number of defects was accompanied by greater aggregation at the expense of the c(2 × 2) structure.

  6. Improved virus removal in ceramic depth filters modified with MgO.

    Science.gov (United States)

    Michen, Benjamin; Fritsch, Johannes; Aneziris, Christos; Graule, Thomas

    2013-02-05

    Ceramic filters, working on the depth filtration principle, are known to improve drinking water quality by removing human pathogenic microorganisms from contaminated water. However, these microfilters show no sufficient barrier for viruses having diameters down to 20 nm. Recently, it was shown that the addition of positively charged materials, for example, iron oxyhydroxide, can improve virus removal by adsorption mechanisms. In this work, we modified a common ceramic filter based on diatomaceous earth by introducing a novel virus adsorbent material, magnesium oxyhydroxide, into the filter matrix. Such filters showed an improved removal of about 4-log in regard to bacteriophages MS2 and PhiX174. This is explained with the electrostatic enhanced adsorption approach that is the favorable adsorption of negatively charged viruses onto positively charged patches in an otherwise negatively charged filter matrix. Furthermore, we provide theoretical evidence applying calculations according to Derjaguin-Landau-Verwey-Overbeek theory to strengthen our experimental results. However, modified filters showed a significant variance in virus removal efficiency over the course of long-term filtration experiments with virus removal increasing with filter operation time (or filter aging). This is explained by transformational changes of MgO in the filter upon contact with water. It also demonstrates that filter history is of great concern when filters working on the adsorption principles are evaluated in regard to their retention performance as their surface characteristics may alter with use.

  7. Selective radiative cooling with MgO and/or LiF layers

    Science.gov (United States)

    Berdahl, P.H.

    1984-09-14

    A selective radiation cooling material which is absorptive only in the 8 to 13 microns wavelength range is accomplished by placing ceramic magnesium oxide and/or polycrystalline lithium fluoride on an infrared-reflective substrate. The reflecting substrate may be a metallic coating, foil or sheet, such as aluminum, which reflects all atmospheric radiation from 0.3 to 8 microns, the magnesium oxide and lithium fluoride being nonabsorptive at those wavelengths. MgO and/or LiF layer is diffusely scattering, but still nonabsorbing, in the wavelength range of 0.3 to 8 microns. At wavelengths from 8 to 13 microns, the magnesium oxide and lithium fluoride radiate power through the ''window'' in the atmosphere, and thus remove heat from the reflecting sheet of material and the attached object to be cooled. At wavelengths longer than 13 microns, the magnesium oxide and lithium fluoride reflects the atmospheric radiation back into the atmosphere. This high reflectance is only obtained if the surface is sufficiently smooth: roughness on a scale of 1 micron is permissible but roughness on a scale of 10 microns is not. An infrared-transmitting cover or shield is mounted in spaced relationship to the material to reduce convective heat transfer. If this is utilized in direct sunlight, the infrared transmitting cover or shield should be opaque in the solar spectrum of 0.3 to 3 microns.

  8. Three-dimensional electron backscattered diffraction analysis of deformation in MgO micropillars

    Energy Technology Data Exchange (ETDEWEB)

    Korte, S., E-mail: sandra.korte@cantab.net [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Ritter, M. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Jiao, C. [FEI Company, Achtseweg Noord 5, 5651 GG Eindhoven (Netherlands); Midgley, P.A.; Clegg, W.J. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2011-11-15

    Small-scale testing is extensively used to study the effects of size on plasticity or characterise plastic deformation of brittle materials, where cracking is suppressed on the microscale. Geometrical and experimental constraints have been shown to affect small-scale deformation and efforts are underway to understand these better. However, current analytical techniques tend to possess high resolution in only one or two dimensions, impeding a detailed analysis of the entire deformed volume. Here electron backscattered diffraction in three dimensions is presented as a way of characterising three-dimensional (3-D) deformation at high spatial resolution. It is shown that, by reconstruction of compressed and then successively sliced and indexed MgO micropillars, this 3-D technique yields information complementary to {mu}-Laue diffraction or electron microscopy, allowing a correlation of experimental artefacts and the distribution of plasticity. In addition, deformation features which are difficult to visualise by standard scanning electron microscopy are easily detected, for example where only small surface traces are produced or minimal plastic strain can be introduced before failure in brittle materials.

  9. Promoting alkali and alkaline-earth metals on MgO for enhancing CO2 capture by first-principles calculations.

    Science.gov (United States)

    Kim, Kiwoong; Han, Jeong Woo; Lee, Kwang Soon; Lee, Won Bo

    2014-12-07

    Developing next-generation solid sorbents to improve the economy of pre- and post-combustion carbon capture processes has been challenging for many researchers. Magnesium oxide (MgO) is a promising sorbent because of its moderate sorption-desorption temperature and low heat of sorption. However, its low sorption capacity and thermal instability need to be improved. Various metal-promoted MgO sorbents have been experimentally developed to enhance the CO2 sorption capacities. Nevertheless, rigorous computational studies to screen an optimal metal promoter have been limited to date. We conducted first-principles calculations to select metal promoters of MgO sorbents. Five alkali (Li-, Na-, K-, Rb-, and Cs-) and 4 alkaline earth metals (Be-, Ca-, Sr-, and Ba-) were chosen as a set of promoters. Compared with the CO2 adsorption energy on pure MgO, the adsorption energy on the metal-promoted MgO sorbents is higher, except for the Na-promoter, which indicates that metal promotion on MgO is an efficient approach to enhance the sorption capacities. Based on the stabilized binding of promoters on the MgO surface and the regenerability of sorbents, Li, Ca, and Sr were identified as adequate promoters among the 9 metals on the basis of PW91/GGA augmented with DFT+D2. The adsorption energies of CO2 on metal-promoted MgO sorbents for Li, Ca, and Sr atoms are -1.13, -1.68, and -1.48 eV, respectively.

  10. Formation mechanism, degradation behavior, and cytocompatibility of a nanorod-shaped HA and pore-sealed MgO bilayer coating on magnesium.

    Science.gov (United States)

    Li, Bo; Han, Yong; Qi, Kai

    2014-10-22

    A novel bilayer coating (HT24h) was fabricated on magnesium using microarc oxidation (MAO) and hydrothermal treatment (HT). The coating comprises an outer layer of narrow interrod spaced hydroxyapatite (HA) nanorods and an inner layer of MgO containing Mg(OH)2/HA-sealing-pores. The hydrothermal formation mechanism of HA nanorods on MAO-formed MgO was explored. Also, evolution of structure and bonding integrity of HT24h coating with immersion in physiological saline (PS) for 0-90 days, corrosion resistance and cytocompatibility of the coating were investigated, together with MgO containing Mg(OH)2-sealing-pores (HT2h) and porous MgO (MAO) coatings. Corrosion resistance was identified by three-point bending and electrochemical tests in PS, while cytocompatibility was determined by MTT, live/dead staining, and vinculin-actin-nucleus tricolor staining assays of hFOB1.19 cells. Immersion tests indicate that cracking rather than delamination is a common feature in most areas of the coatings up to day 90 and degradation is the reason for thinning in thickness of the coatings. MAO and HT2h coatings exhibit a significant thinning due to fast degradation of MgO. However, HT24h coating shows a quite small thinning, owing to the fact that the HA nanorods underwent quite slow degradation while the underlying MgO only underwent conversion to Mg(OH)2 without dissolution of the Mg(OH)2. Scratch tests reveal that HT24h coating still retains relatively high bonding integrity, although the failure position changes from the MgO interior to a point between the HA and MgO layers after 90 days of immersion. HT24h coating appears far more effective than MAO and HT2h coatings in reducing degradation and maintaining the mechanical integrity of Mg, as well as enhancing the mitochondrial activity, adhesion, and proliferation of osteoblasts.

  11. Nano SiO2 and MgO improve the properties of porous β-TCP scaffolds via advanced manufacturing technology.

    Science.gov (United States)

    Gao, Chengde; Wei, Pingpin; Feng, Pei; Xiao, Tao; Shuai, Cijun; Peng, Shuping

    2015-03-25

    Nano SiO2 and MgO particles were incorporated into β-tricalcium phosphate (β-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical β-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped β-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from β-TCP to α-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 ± 0.36 MPa (β-TCP) to 5.74 ± 0.62 MPa (β-TCP/SiO2), 9.02 ± 0.55 MPa (β-TCP/MgO) and 10.43 ± 0.28 MPa (β-TCP/SiO2/MgO), respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of β-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of β-TCP scaffold.

  12. The theme of Jiang Cao terror works%姜草恐怖作品的主题研究

    Institute of Scientific and Technical Information of China (English)

    刘红芹

    2014-01-01

    韩国艺术家姜草的恐怖作品非常有特色,他一改以往恐怖作品的风格与特点,在作品中表现出高度的人文关怀。他的几部恐怖作品,主题表现出了某种程度的一致性,笔者就异化主题,时间主题与拯救主题进行细致的探究,试图挖掘姜草作品背后思路与主题的连贯与相关性,从而更好地理解姜草及作品。主题研究这个思路起源于德国民俗学,通常的主题研究,是指由纵向的角度对艺术家的作品进行探索,整体性地关注作品及作者的精神世界,从而丰富对作品及作者的阅读。%Korean artist ,Jiang Cao's terror works are very distinctive .He changed the terror work style and charac-teristic,showing high degree of human concern in the works .Several of his horror works ,subjects showed some de-gree of consistency ,the theme of alienation ,time subject and theme of salvation and meticulous research ,trying to dig out the ginger grass works behind the ideas and themes of coherence and relevance , and thus a better under-standing of ginger grass and works .The theme of this idea originated from German folklore ,the subject study usual-ly,refers to the exploration of the vertical angle of the artist's work,the whole attention to works and the author's spiritual world ,thus enriching the works and the author's reading .

  13. First-principles calculations of optical properties of perfect and defective MgO crystals at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    He, L., E-mail: linhe63@yahoo.com.cn [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068 (China); Tang, M.J. [College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068 (China); Zeng, M.F. [Department of Fundamental Education, Chengdu Vocational and Technical College, Chengdu 610041 (China); Zhou, X.M.; Zhu, W.J. [National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, CAEP, Mianyang 621900 (China); Liu, F.S. [Institute of High-pressure Physics, Southwest Jiaotong University, Chengdu 610031 (China)

    2013-02-01

    The optical-absorption and refractive-index properties of MgO crystal without and with doubly charged Mg and O vacancies (V{sub Mg}{sup -2} and V{sub O}{sup +2}) up to 100 GPa were calculated using the first-principles method. The obtained data were mainly used to explore origins of the observed optical-transparency loss and behaviors of the refractive-index change for MgO under relatively strong shock compression. Results show that the V{sub O}{sup +2}-induced heterogeneous absorption within {approx}300-700 nm should be a source causing the transparency loss. It is found that the refractive index of perfect MgO at 532 nm increases with shock pressure. The V{sub O}{sup +2} leads to a rise in refractive index, and the increment increases with shock pressure. If the vacancy concentration increases with shock pressure, effects of the V{sub O}{sup +2} on refractive index are enhanced further.

  14. Properties of alkali metal atoms deposited on a MgO surface: a systematic experimental and theoretical study.

    Science.gov (United States)

    Finazzi, Emanuele; Di Valentin, Cristiana; Pacchioni, Gianfranco; Chiesa, Mario; Giamello, Elio; Gao, Hongjun; Lian, Jichun; Risse, Thomas; Freund, Hans-Joachim

    2008-01-01

    The adsorption of small amounts of alkali metal atoms (Li, Na, K, Rb, and Cs) on the surface of MgO powders and thin films has been studied by means of EPR spectroscopy and DFT calculations. From a comparison of the measured and computed g values and hyperfine coupling constants (hfccs), a tentative assignment of the preferred adsorption sites is proposed. All atoms bind preferentially to surface oxide anions, but the location of these anions differs as a function of the deposition temperature and alkali metal. Lithium forms relatively strong bonds with MgO and can be stabilized at low temperatures on terrace sites. Potassium interacts very weakly with MgO and is stabilized only at specific sites, such as at reverse corners where it can interact simultaneously with three surface oxygen atoms (rubidium and cesium presumably behave in the same way). Sodium forms bonds of intermediate strength and could, in principle, populate more than a single site when deposited at room temperature. In all cases, large deviations of the hfccs from the gas-phase values are observed. These reductions in the hfccs are due to polarization effects and are not connected to ionization of the alkali metal, which would lead to the formation of an adsorbed cation and a trapped electron. In this respect, hydrogen atoms behave completely differently. Under similar conditions, they form (H(+))(e(-)) pairs. The reasons for this different behavior are discussed.

  15. Non-resonant microwave absorption studies of superconducting MgB2 and MgB2 + MgO

    Indian Academy of Sciences (India)

    Janhavi P Joshi; Subhasis Sarangi; A K Sood; Dilip Pal; S V Bhat

    2002-02-01

    Non-resonant microwave absorption (NRMA) studies of superconducting MgB2 and a sample containing ∼ 10% by weight of MgO in MgB2 are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB2 sample. A linear temperature dependence of the lower critical field c1 is observed indicating a non- wave superconductivity. However, the phase reversal of the NRMA signal which could suggest wave symmetry is also not observed. In the MgB2 + MgO sample, much larger low field dependent absorption is observed indicating the presence of intergranular weak links. The hysteretic behavior of NRMA is compared and contrasted in the two samples. In the pure MgB2 sample, a large hysteresis is observed between the forward and the reverse scans of the magnetic field indicating strong pinning of flux lines. This hysteresis saturates a few degrees below c while in the MgB2 + MgO sample, a much slower increase of hysteresis with decreasing temperature is observed, a signature of weaker pinning.

  16. Comparing the Electrochemical Performance of LiFePO4/C Modified by Mg Doping and MgO Coating

    Directory of Open Access Journals (Sweden)

    Jianjun Song

    2013-01-01

    Full Text Available Supervalent cation doping and metal oxide coating are the most efficacious and popular methods to optimize the property of LiFePO4 lithium battery material. Mg-doped and MgO-coated LiFePO4/C were synthesized to analyze their individual influence on the electrochemical performance of active material. The specific capacity and rate capability of LiFePO4/C are improved by both MgO coating and Mg doping, especially the Mg-doped sample—Li0.985Mg0.015FePO4/C, whose discharge capacity is up to 163 mAh g−1, 145.5 mAh g−1, 128.3 mAh g−1, and 103.7 mAh g−1 at 1 C, 2 C, 5 C, and 10 C, respectively. The cyclic life of electrode is obviously increased by MgO surface modification, and the discharge capacity retention rate of sample LiFePO4/C-MgO2.5 is up to 104.2% after 100 cycles. Comparing samples modified by these two methods, Mg doping is more prominent on prompting the capacity and rate capability of LiFePO4, while MgO coating is superior in terms of improving cyclic performance.

  17. Synthesis and luminescence properties of MgO: Sm3+ phosphor for white light-emitting diodes

    Science.gov (United States)

    Kiran, Nallamala; Baker, A. P.; Wang, Gui-Gen

    2017-02-01

    MgO: xSm3+ (0.02 ≤ x ≤ 0.08) red phosphors are prepared by low temperature solution combustion method. The MgO: XSm3+ phosphor characterized by X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FE-SEM), luminescence and decay time measurements. The results of XRD and FE-SEM show that resultant samples are single phase. The vibration properties MgO phosphor was studied by Fourier transform infrared spectroscopy. The luminescence spectra exhibits four emission bands at 566, 603, 651 and 708 nm corresponding to the various transition from 4G5/2 ground state to lower lying levels 6H5/2, 6H7/2, 6H9/2 and 6H11/2 states, with an excitation wavelength at 404 nm. The chromaticity coordinates have been estimated from the emission spectra and the suitability of title phosphor for white light applications. The lifetime corresponding to the 4G5/2 level of the title phosphor has been found to decrease with the increase in Sm3+ ion concentration.

  18. Nucleation and mobility model of Agn clusters adsorbed on perfect and oxygen vacancy MgO surfaces.

    Science.gov (United States)

    Liu, Yongfei; Wang, Yan; Chen, Guangju

    2011-05-01

    The structures and energy properties for Ag(n) (n = 1-8) metal clusters adsorbed on the perfect and oxygen vacancy MgO surfaces have been studied by using the DFT/UB3LYP method with an embedded cluster model. The nucleation and mobility model for the Ag(n) (n = 1-8) clusters on the perfect and oxygen vacancy MgO(100) surfaces was investigated. The results show that the Ag atoms locate initially at the surface oxygen vacancy sites; then, with the growth of Ag cluster sizes, the large Ag clusters move possibly out of the vacancy sites by a rolling model, and diffuse on the MgO surface under a certain temperature condition. The relative energies needed for moving out of the oxygen vacancy region for the adsorbed Ag(n) clusters with the rolling model have been predicted. The even-odd oscillation behaviors for the cohesive energies, nucleation energies, first ionization potentials and HOMO-LUMO gaps of the adsorbed Ag(n) clusters with the variation of cluster sizes have also been discussed.

  19. Visible Color Tunable Emission in Three-Dimensional Light Emitting Diodes by MgO Passivation of Pyramid Tip.

    Science.gov (United States)

    Kim, Ji-Hyun; Ye, Byeong Uk; Park, Joonmo; Yoo, Chul Jong; Kim, Buem Joon; Jeong, Hu Young; Hur, Jin-Hoe; Kim, Jong Kyu; Lee, Jong-Lam; Baik, Jeong Min

    2015-12-23

    We demonstrated visible color tunable three-dimensional (3D) pyramidal light emitting diodes by depositing the MgO on and near the tip of the pyramid as an insulating layer. Here, we show that the degradation of the materials (i.e., p-GaN) crystallinity and the built-in electric field due to the nanoscale geometry of the tip region is responsible for the large leakage current observed in LEDs. Confocal scanning electroluminescence microscopy images clearly showed that the intensity of the light emitted out of the side facet of the pyramid is much higher than that of the light extracted out of the tip surface, indicating that the MgO layer prohibited the carrier injection to the MQWs layer, suppressing the leakage occurring at or near the tip region of the pyramids. The color range of the LEDs can be also tuned by using the MgO layer, a blue-shift by 10.3 nm in the wavelength. This technique is simple and scalable, providing a promising solution for developing 3D pyramidal LEDs with low leakage current and controllable light emission.

  20. Evaluation of novel reactive MgO activated slag binder for the immobilisation of lead and zinc.

    Science.gov (United States)

    Jin, Fei; Al-Tabbaa, Abir

    2014-12-01

    Although Portland cement is the most widely used binder in the stabilisation/solidification (S/S) processes, slag-based binders have gained significant attention recently due to their economic and environmental merits. In the present study, a novel binder, reactive MgO activated slag, is compared with hydrated lime activated slag in the immobilisation of lead and zinc. A series of lead or zinc-doped pastes and mortars were prepared with metal to binder ratio from 0.25% to 1%. The hydration products and microstructure were studied by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The major hydration products were calcium silicate hydrate and hydrotalcite-like phases. The unconfined compressive strength was measured up to 160 d. Findings show that lead had a slight influence on the strength of MgO-slag paste while zinc reduced the strength significantly as its concentration increased. Leachate results using the TCLP tests revealed that the immobilisation degree was dependent on the pH and reactive MgO activated slag showed an increased pH buffering capacity, and thus improved the immobilisation efficiency compared to lime activated slag. It was proposed that zinc was mainly immobilised within the structure of the hydrotalcite-like phases or in the form of calcium zincate, while lead was primarily precipitated as the hydroxide. It is concluded, therefore, that reactive MgO activated slag can serve as clinker-free alternative binder in the S/S process.

  1. Atomic Layer Deposition of MgO Nanofilms on BaMgAl10O17:Eu2+ Blue Phosphors

    Directory of Open Access Journals (Sweden)

    Hyug Jong Kim

    2011-01-01

    Full Text Available This paper reports the growth of MgO nanofilms on BaMgAl10O17:Eu2+ blue phosphors by using the atomic layer deposition method. MgO films were prepared at 120°C by using Mg(CpEt2 and H2O as the precursor and reactant gas, respectively. X-ray photoelectron spectroscopy (XPS analysis showed that the Mg peak of the coated powders was higher than that of the uncoated powders. This confirmed that the surface of the coated phosphor powder comprised MgO nanoscale film. Through TEM and FE-SEM analysis, it was observed that the growth rate was about 0.33 Å/cycle and that the surface morphology of the coated phosphors was smoother and clearer than that of uncoated phosphor. The photoluminescence (PL intensity for the coated phosphors was 5%–19% higher than that of uncoated phosphor. This means that the reactive surface is uniformly grown with stable magnesium oxide to reduce the dead surface layer without change of bulk properties.

  2. Effects of Basicity and MgO in Slag on the Behaviors of Smelting Vanadium Titanomagnetite in the Direct Reduction-Electric Furnace Process

    Directory of Open Access Journals (Sweden)

    Tao Jiang

    2016-05-01

    Full Text Available The effects of basicity and MgO content on reduction behavior and separation of iron and slag during smelting vanadium titanomagnetite by electric furnace were investigated. The reduction behaviors affect the separation of iron and slag in the direct reduction-electric furnace process. The recovery rates of Fe, V, and Ti grades in iron were analyzed to determine the effects of basicity and MgO content on the reduction of iron oxides, vanadium oxides, and titanium oxides. The chemical compositions of vanadium-bearing iron and main phases of titanium slag were detected by XRF and XRD, respectively. The results show that the higher level of basicity is beneficial to the reduction ofiron oxides and vanadium oxides, and titanium content dropped in molten iron with the increasing basicity. As the content of MgO increased, the recovery rate of Fe increased slightly but the recovery rate of V increased considerably. The grades of Ti in molten iron were at a low level without significant change when MgO content was below 11%, but increased as MgO content increased to 12.75%. The optimum conditions for smelting vanadium titanomagnetite were about 11.38% content of MgO and quaternary basicity was about 1.10. The product, vanadium-bearing iron, can be applied in the converter steelmaking process, and titanium slag containing 50.34% TiO2 can be used by the acid leaching method.

  3. Theoretical aspects of methyl acetate and methanol activation on MgO(100) and (501) catalyst surfaces with application in FAME production

    Science.gov (United States)

    Man, Isabela-Costinela; Soriga, Stefan Gabriel; Parvulescu, Vasile

    2017-01-01

    Density functional theory (DFT) calculations were carried out to study the activation of methyl acetate and methanol on MgO(100) and MgO(501) surfaces and integrated in the context of transesterification, interesterification and glycerolysis reactions used in biodiesel industry. First results indicate the importance of including of dispersion forces in the calculations. On MgO(100) the reverse reactions steps of Csbnd O and Csbnd H dissociations and on MgO(501) the same reverse reaction step of Csbnd H dissociations of methyl acetate are energetically favorable, while the dissociation of Csbnd O bond into methoxide and acetate fragments on the edge of MgO(501) was found to be exothermic with a low activation energy. For methanol, the dissociation of Osbnd H bond on MgO(100) surface in the presence of the second coadsorbed methanol molecule becomes more energetically favoured compared to the isolated molecule, due to the fact that the methoxide fragment is stabilized by intermolecular hydrogen bonding. This is reflected by the decrease of the activation energy of the forward reaction step and the increase of the activation energy of the backward reaction step, increasing the probability to have dissociated molecules among the undissociated ones. These results represent a step forward for better understanding from atomistic point of view the paths of these reactions on these surfaces for the corresponding catalytic processes.

  4. Effects of MgO promoter on properties of Ni/Al2O3 catalysts for partial oxidation of methane to syngas

    Institute of Scientific and Technical Information of China (English)

    QIU Yejun; CHEN Jixiang; ZHANG Jiyan

    2007-01-01

    The effects of MgO promoter on the physicochemical properties and catalytic performance of Ni/Al2O3 catalysts for the partial oxidation of methane to syngas were studied by means of BET,XRD,H2-TPR,TEM and performance evaluation.It was found that the MgO promoter benefited from the uniformity of nickel species in the catalysts,inhibited the formation of NiAl2O4 spinel and improved the interaction between nickel species and support.These results were related to the formation of NiO-MgO solid solution and MgAl2O4 spinel.Moreover,for the catalysts with a proper amount of MgO promoter,the nickel dispersiveness was enhanced,therefore making their catalytic performance in methane partial oxidation improved.However,the excessive MgO promoter exerted a negative effect on the catalytic performance.Meanwhile,the basicity of MgO promoted the reversed water-gas shift reaction,which led to an increase in CO selectivity and a decrease in H2 selectivity.The suitable content of MgO promoter in Ni/Al2O3 catalyst was~7 wt-%.

  5. Effect of MgO content in sinter on the softening-melting behavior of mixed burden made from chromium-bearing vanadium-titanium magnetite

    Institute of Scientific and Technical Information of China (English)

    Xiang-xin Xue

    2016-01-01

    The effect of sinter with different MgO contents on the softening–melting behavior of mixed burden made from chro-mium-bearing vanadium–titanium magnetite was investigated. The results show that with increasing MgO content in the sinter, the softening interval and melting interval increased and the location of the cohesive zone shifted downward slightly and became moderately thicker. The softening–melting characteristic value was less pronounced when the MgO content in the sinter was 2.98wt%–3.40wt%. Increasing MgO content in the sinter reduced the content and recovery of V and Cr in the dripped iron. In addition, greater MgO contents in the sinter resulted in the generation of greater amounts of high-melting-point components, which adversely affected the permeability of the mixed burden. When the softening–melting behavior of the mixed burden and the recovery of valuable elements were taken into account, proper MgO con-tents in the sinter and slag ranged from 2.98wt% to 3.40wt% and from 11.46wt% to 12.72wt%, respectively, for the smelting of burden made from chromium-bearing vanadium–titanium magnetite in a blast furnace.

  6. Efeito do íon comum na reação de hidratação do MgO Common-ion effect on the MgO hydration reaction

    Directory of Open Access Journals (Sweden)

    L. F. Amaral

    2008-03-01

    Full Text Available Concretos refratários contendo óxido de magnésio (MgO apresentam grande interesse tecnológico por unir a versatilidade e a liberdade de design dos refratários monolíticos aos benefícios conferidos pelo MgO, tais como, elevada refratariedade e resistência a escórias básicas. Entretanto, o MgO é facilmente hidratado formando Mg(OH2 e essa reação leva a uma grande expansão volumétrica do material, o que limita sua aplicação em concretos refratários. Para encontrar soluções que minimizem esse efeito, torna-se necessário uma melhor compreensão a respeito dos fatores que afetam essa reação, como a temperatura. Neste trabalho, o impacto do deslocamento de equilíbrio químico conhecido como efeito do íon comum na hidratação do MgO foi avaliado na presença de diversos aditivos (MgCl2, MgSO4, CaCl2 e KOH. Entre os aditivos, o CaCl2 comportou-se como um retardador da reação, enquanto um comportamento oposto foi obtido para o KOH. O MgCl2 e o MgSO4 apresentaram ambos os efeitos dependendo de suas concentrações na suspensão. As possíveis causas para esses comportamentos são discutidas no artigo. Os resultados foram abordados considerando-se a termodinâmica e a cinética da reação, bem como os conseqüentes danos mecânicos causados ao material.MgO based refratory castables present a wide technological interest because they add together the versatility and the installation efficiency of the monolithic refractories to the intrinsic MgO properties, such as high refractoriness and resistance to basic slag corrosion. Nevertheless, MgO is easily hydrated by water generating Mg(OH2 and this reaction causes a volumetric expansion that could lead to material’s breakdown and inhibit its application in refractory castables. In order to develop solutions to minimize this effect, it is necessary a better understanding of the main variables involved in this reaction, such as temperature. In this work, the impact of the chemical

  7. Use of CaO as an activator for producing a price-competitive non-cement structural binder using ground granulated blast furnace slag

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Sik; Jun, Yubin; Lee, Changha, E-mail: clee@unist.ac.kr; Oh, Jae Eun, E-mail: ohjaeeun@unist.ac.kr

    2013-12-15

    The use of calcium oxide (CaO) demonstrates a superior potential for the activation of ground granulated blast furnace slag (GGBFS), and it produces a higher mechanical strength than calcium hydroxide [Ca(OH){sub 2}]. The mechanical strength differences between CaO- and Ca(OH){sub 2}-activated GGBFS binders are explored using isothermal calorimetry, powder X-ray diffraction, thermogravimetric and differential thermal analysis (TGA and DTA) as well as compressive strength testing. Calcium silicate hydrate (C–S–H), Ca(OH){sub 2} and a hydrotalcite-like phase are found as reaction products in all samples. The TGA and DTA results indicate that the use of CaO produces more C–S–H, although this is not likely to be the primary cause of higher strength development in the CaO-activated GGBFS. Rather, other factors such as porosity may govern the strength at a higher order of magnitude. Significant reduction of Ca(OH){sub 2} occurs only with the use of Ca(OH){sub 2}, followed by the formation of carbonate (CaCO{sub 3}), indicating carbonation. -- Highlights: •CaO showed a better potential for the activation of GGBFS than Ca(OH){sub 2}. •Strength test, XRD, TGA/DTA and isothermal calorimetry are used. •C-S-H, Ca(OH){sub 2}, and a hydrotalcite-like phase are found in all samples. •The use of Ca(OH){sub 2} causes some degree of carbonation.

  8. THE INFLUENCE OF CaO AND P2O5 OF BONE ASH UPON THE REACTIVITY AND THE BURNABILITY OF CEMENT RAW MIXTURES

    Directory of Open Access Journals (Sweden)

    TOMÁŠ IFKA

    2012-03-01

    Full Text Available The influence of CaO and P2O5 upon the reactivity of cement raw meal was investigated in this paper. Ash of bone meal containing Ca3(PO42 - 3CaO·P2O5 was used as the source of P2O5. Two series of samples with different content of the ash of bone meal were prepared. In the first series, the ash of bone was added into cement raw meal. The second series of samples were prepared by considering ash as one of CaO sources. Therefore, the total content of CaO in cement raw meal was kept constant, while the amount of P2O5 increased. These different series of samples were investigated by analyzing free lime content in the clinkers. The XRD analysis and Electron Micro Probe Analyzer analysis of the clinkers were also carried out. Two parameters were used to characterize the reactivity of cement raw meal: content of free lime and Burnability Index (BI calculated from free lime content in both series of samples burnt at 1350 ºC, 1400 ºC, 1450 ºC and 1500 ºC. According to the first parameter, P2O5 content that drastically makes worse the reactivity of cement raw meal was found at 1.11 wt.% in the first series, while this limit has reached 1.52 wt.% in the second one. According to the BI, the limit of P2O5 was found at 1.42 wt. % in the first series and 1, 61 wt.% in the second one. Furthermore, EPMA has demonstrated the presence of P2O5 in both calcium silicate phases forming thus solid solutions.

  9. Crystallization paths in SiO2-Al2O3-CaO system as a genotype of silicate materials

    Science.gov (United States)

    Lutsyk, V. I.; Zelenaya, A. E.

    2013-12-01

    The phases trajectories in the fields of primary crystallization of cristobalite (SiO2cr), tridymite (SiO2tr), mullite (3Al2O3-2SiO2) and in a field of liquid immiscibility are analyzed on a basis of computer model for T-x-y diagram of SiO2-Al2O3-CaO system. The concentration fields with unique set of microconstituents and the fields without individual crystallization schemes and microconstituents are revealed.

  10. El impacto en la ciencia económica de la teoría del caos y de los fractales: Teoría y aplicaciones

    OpenAIRE

    Andrés Fernández Díaz

    2015-01-01

    La complejidad constituye una de las características más importantes del comportamiento económico. El nuevo campo de conocimiento denominado Dinámica Caótica en Economía nació precisamente con el objetivo de comprender, estructurar y explicar de manera endógena tal complejidad. En este artículo, y tras exponer los principales conceptos y técnicas de las matemáticas del caos y de la geometría fractal, se analizan las posibilidades de aplicación de estos importantes instrumentos a las diferente...

  11. Ciencias de la complejidad y caos como herramientas en el análisis de la proliferación de vectores y zoonosis

    OpenAIRE

    2009-01-01

    En el presente trabajo se discuten los fundamentos de las ciencias de la complejidad y caos como herramientas en el análisis la proliferación de vectores y zoonosis. En la primera parte del artículo se describen los fundamentos y antecedentes de las ciencias de la complejidad, como una visión diferente para entender y analizar a los sistemas dinámicos, conceptos que han existido desde hace varios siglos y están relacionados con las ideas acerca del origen de la vida misma, que romperán con lo...

  12. Evaluation of Component Activity in Molten MnO-SiO2-Al2O3-CaO System with Model SELF-SReM4

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A sub-regular solution model SE LF-SReM4 used to evaluate activity of the components in a homogeneous region of a quaternary system has been developed in Shanghai Enhanced Laboratory of Ferrometallurgy. The application of SELF-SReM4 in C-Mn-Fe-Si system without the SiC formation has been introduced in previous paper. It′s application for molten slag of MnO-SiO2-Al2O3-CaO was introduced in this paper. They provide a basis for the prediction of the metal-slag equilibrium conditions.

  13. The Influence of Calcined Clay Pozzolan, Low-Cao Steel Slag and Granite Dust On the Alkali-Silica Reaction in Concrete

    OpenAIRE

    James Sarfo-Ansah; Eugene Atiemo

    2015-01-01

    The influence of low CaO steel slag, calcined clay and granite dust on the alkali-silica reaction was investigated over a period of 35 days under accelerated curing conditions. The mineral admixtures were used to replace varying portions of high alkali Portland limestone cement up to an admixture content of 25% in order to study their effect on the alkali-silica reaction (ASR). Portland limestone cement used for the study had a total Na2Oeq of 4.32. XRD analysis of hydrated mortar...

  14. Análisis, construcción, simulación y sincronización de circuitos electrónicos prototipos de Caos

    OpenAIRE

    Bordel Sánchez, Borja

    2014-01-01

    El proyecto tiene como objetivo el estudio de siete Sistemas Dinámicos, yendo de los que son paradigma de Caos a los más complejos, y sus posibles aplicaciones en comunicaciones privadas, bioingeniería y comunicaciones ópticas. El conjunto de sistemas seleccionados incluye algunos ejemplos paradigmáticos de Dinámicas Caóticas, así como nuevas propuestas, tanto de do sistemas básicos como de un sistema que tiene soluciones más complejas, nunca antes estudiados. Se logrará, de esta manera, rea...

  15. [Classes of crude drugs and its distribution of producing area in the attached illustrations in Ben cao tu jing (Illustrated Classic of Materia Medica)].

    Science.gov (United States)

    Xu, T; Peng, H S

    2016-03-01

    Ben cao tu jing (Illustrated Classic of Materia Medica) is the earliest extant atlas book of materia medica in China, with 933 attached drawings. Among them, the largest portion, amounting to 670, are herbaceous plants, mostly commonly used, with definite marks of the origin producing areas, distributed across 149 administrative divisions(prefectures and counties) of the Song Dynasty, most of them in Northern area which were distributed denser than those in Southern area. The densest ones were located in Southern Shanxi, Eastern Sichuan and Eastern Anhui. In the attached drawings, the frequency of highest occurrence appeared in this Classic are three prefectures, Chuzhou, Shizhou and Guangzhou.

  16. Steam-Coal Gasification Using CaO and KOH for in Situ Carbon and Sulfur Capture

    Energy Technology Data Exchange (ETDEWEB)

    Siefert, Nicholas S. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Carnegie Mellon Univ., Pittsburgh, PA (United States); Shekhawat, Dushyant [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Litster, Shawn [Carnegie Mellon Univ., Pittsburgh, PA (United States); Berry, David A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2013-08-15

    We present experimental results of coal gasification with and without the addition of calcium oxide and potassium hydroxide as dual-functioning catalyst-capture agents. Using two different coal types and temperatures between 700 and 900 °C, we studied the effect of these catalyst-capture agents on (1) the syngas composition, (2) CO2 and H2S capture, and (3) the steam-coal gasification kinetic rate. The syngas composition from the gasifier was roughly 20% methane, 70% hydrogen, and 10% other species when a CaO/C molar ratio of 0.5 was added. We demonstrated significantly enhanced steam–coal gasification kinetic rates when adding small amounts of potassium hydroxide to coal when operating a CaO-CaCO3 chemical looping gasification reactor. For example, the steam–coal gasification kinetic rate increased 250% when dry mixing calcium oxide at a Ca/C molar ratio of 0.5 with a sub-bituminous coal, and the kinetic rate increased 1000% when aqueously mixing calcium oxide at a Ca/C molar ratio of 0.5 along with potassium hydroxide at a K/C molar ratio of 0.06. In addition, we conducted multi-cycle studies in which CaCO3 was calcined by heating to 900 °C to regenerate the CaO, which was then reused in repeated CaO-CaCO3 cycles. The increased steam-coal gasification kinetics rates for both CaO and CaO + KOH persisted even when the material was reused in six cycles of gasification and calcination. The ability of CaO to capture carbon dioxide decreased roughly 2-4% per CaO-CaCO3 cycle. We also discuss an important application of this combined gasifier-calciner to electricity generation and selling the purge stream as a precalcined feedstock to a cement kiln. In this scenario, the amount of purge stream required is fixed not by the degradation in the capture ability but rather by the requirements at the cement kiln on the amount of CaSO4 and ash in the precalcined feedstock.

  17. Use of heterogeneous CaO and SnO{sub 2} catalysts supported on rice husk ash to produce biodiesel; Emprego de catalisadores heterogeneos de CaO e SnO{sub 2} suportados em cinza de casca de arroz na obtencao de biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Ana Brigida [Instituto Federal do Espirito Santo, Vitoria, ES (Brazil); Silva, Paulo Roberto Nagipe da; Stumbo, Alexandre Moura, E-mail: nagipe@uenf.br [Laboratorio de Ciencias Quimicas, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ (Brazil); Freitas, Jair C.C. [Departamento de Fisica, Centro de Ciencias Exatas, Universidade Federal do Espirito Santo, Vitoria, ES (Brazil)

    2012-07-01

    Silica obtained from rice husk after acid leaching and calcination was compared to commercial silica as a catalyst support. CaO and SnO{sub 2} catalysts were prepared by impregnation and tested in the transesterification of soybean oil and the esterification of oleic acid. CaO catalysts showed basic character and were the most active for transesterification, whereas SnO{sub 2} catalysts were acid and the most effective for esterification. In both cases the performances of the catalysts prepared with rice husk ash and commercial silica were similar. These results demonstrate that rice husk is a cost-effective and environmentally-friendly source of silica that can be used as a catalyst support. (author)

  18. Modeling the viscosity of silicate melts containing manganese oxide

    Directory of Open Access Journals (Sweden)

    Kim Wan-Yi

    2013-01-01

    Full Text Available Our recently developed model for the viscosity of silicate melts is applied to describe and predict the viscosities of oxide melts containing manganese oxide. The model requires three pairs of adjustable parameters that describe the viscosities in three systems: pure MnO, MnO-SiO2 and MnO-Al2O3-SiO2. The viscosity of other ternary and multicomponent silicate melts containing MnO is then predicted by the model without any additional adjustable model parameters. Experimental viscosity data are reviewed for melts formed by MnO with SiO2, Al2O3, CaO, MgO, PbO, Na2O and K2O. The deviation of the available experimental data from the viscosities predicted by the model is shown to be within experimental error limits.

  19. Water/Rock Interactions and Changes in Chemical Composition During Zeolite Mineralization

    Institute of Scientific and Technical Information of China (English)

    张寿庭; 赵鹏大; 徐旃章; 郑明华

    2001-01-01

    Systematic analysis and comparative study of the chemical compositions of rocks and ores from the main types of zeolite deposits in the surroundings of the Songliao Basin have shown that the process of formation of zeolite from volcanic and pyroclastic rocks is generally characterized by the relative purification of SiO2, i.e., SiO2/A12O3 ratios tend to increase, al kali earth elements (CaO + MgO) and H2O are relatively enriched, and the alkali metals (K2O + Na2O) are depleted in their total amount. The alkali metals K and Na follow different rules of migration and enrichment during the formation of mordenite and clinoptilolite. In the pro cess of formation of mordenite more Na+ will be imported and K+ will be lost remarkably. On the contrary, in the process of formation clinoptilolite more K+ will be incorporated and Na+will become obviously depleted.

  20. 江西大余压性断裂带一些化学测试数据的初步分析

    Institute of Scientific and Technical Information of China (English)

    孙岩

    1982-01-01

    Discussed in this paper are the relationship between the compressive fault zone and mineralization, and the regularities governing the concentration-dispersion of elements in the compressive fault zone based on chemically determined data from field and laboratory studies of megascopic structures and tectonite. Horizontal zoning has been recognized in the compressive fault zone, with four distinct zones from the centre outwards. Four groups of chemical components in these four zones are distinguished: the first group --SiO2, FeO, MgO and MnO; the second -- Fe2O3, Na2O and K2O; the third -- CaO and Al2O3 ; and the fourth -- TiO2 and P2O5. Furthermore, various tectono-geochemical processes (including dynamic differentiation or mechanical metamorphic differentiation, dynamically thermal metamorphism,oxidation-reduction, and hydrolysis and dewatering) in the fault zone are also discussed in detail.

  1. Análisis estadístico de datos geoquímicos de volcanitas jurásicas del Macizo del Deseado, provincia de Santa Cruz Statistical analysis of geochemical data from Jurassic volcanic rocks of the Deseado Massif, province of Santa Cruz

    OpenAIRE

    M. Alperin; H. Echeveste; R. Fernández; G. Bellieni

    2007-01-01

    Durante el mapeo de detalle de la zona central del macizo del Deseado se reconoció un conjunto de unidades volcánicas jurásicas: lavas e ignimbritas de composición andesítica, dacítica y riolítica. Se realizó un análisis estadístico de los óxidos mayoritarios SiO2, TiO2, Al2O3, FeO (total), MnO, MgO, CaO, Na2O, K2O y P2O5 de 73 muestras provenientes de ocho unidades volcánicas. La composición geoquímica total constituye un conjunto de datos cerrados o datos composicionales ya que la suma de l...

  2. Análisis estadístico de datos geoquímicos de volcanitas jurásicas del Macizo del Deseado, provincia de Santa Cruz

    OpenAIRE

    M. Alperin; H. Echeveste; R. Fernández; G. Bellieni

    2007-01-01

    Durante el mapeo de detalle de la zona central del macizo del Deseado se reconoció un conjunto de unidades volcánicas jurásicas: lavas e ignimbritas de composición andesítica, dacítica y riolítica. Se realizó un análisis estadístico de los óxidos mayoritarios SiO2, TiO2, Al2O3, FeO (total), MnO, MgO, CaO, Na2O, K2O y P2O5 de 73 muestras provenientes de ocho unidades volcánicas. La composición geoquímica total constituye un conjunto de datos cerrados o datos composicionales ya que la suma de l...

  3. Synergetic and inhibition effects in carbon dioxide gasification of blends of coals and biomass fuels of Indian origin.

    Science.gov (United States)

    Satyam Naidu, V; Aghalayam, P; Jayanti, S

    2016-06-01

    The present study investigates the enhancement of CO2 gasification reactivity of coals due to the presence of catalytic elements in biomass such as K2O, CaO, Na2O and MgO. Co-gasification of three Indian coal chars with two biomass chars has been studied using isothermal thermogravimetric analysis (TGA) in CO2 environment at 900, 1000 and 1100°C. The conversion profiles have been used to establish synergetic or inhibitory effect on coal char reactivity by the presence of catalytic elements in biomass char by comparing the 90% conversion time with and without biomass. It is concluded that both biomasses exhibit synergistic behavior when blended with the three coals with casuarina being more synergetic than empty fruit bunch. Some inhibitory effect has been noted for the high ash coal at the highest temperature with higher 90% conversion time for the blend over pure coal, presumably due to diffusional control of the conversion rate.

  4. Solidification/stabilisation of electric arc furnace waste using low grade MgO.

    Science.gov (United States)

    Cubukcuoglu, B; Ouki, S K

    2012-02-01

    This study aims to evaluate the potential of low grade MgO (LGMgO) for the stabilisation/solidification (S/S) of heavy metals in steel electric arc furnace wastes. Relevant characteristics such as setting time, unconfined compressive strength (UCS) and leaching behaviour assessed by acid neutralisation capacity (ANC), monolithic and granular leaching tests were examined in light of the UK landfill Waste Acceptance Criteria (WAC) for disposal. The results demonstrated that all studied mix designs with Portland cement type 1 (CEM1) and LGMgO, CEM1-LGMgO 1:2 and 1:4 at 40% and 70% waste addition met the WAC requirements by means of UCS, initial and final setting times and consistence. Most of the ANC results met the WAC limits where the threshold pH values without acid additions were stable and between 11.9 and 12.2 at 28d. Granular leaching results indicate fixation of most of the metals at all mix ratios. An optimum ratio was obtained at CEM1-LGMgO 1:4 at 40% waste additions where none of the metals leaching exceeded the WAC limits and hence may be considered for landfill disposal. The monolithic leaching test results showed that LGMgO performed satisfactorily with respect to S/S of Zn, as the metal component present at the highest concentration level in the waste exhibited very little leaching and passed the leaching test requirement at all mix ratios studied. However, its performance with respect to Pb, Cd and Cr was less effective in reducing their leaching suggesting a higher cumulative rate under those leaching regimes.

  5. Spectral Analysis of Sm3+& Dy3+ : B2O3-Zno-Mgo Optical Glasses

    Directory of Open Access Journals (Sweden)

    M. Venkateswarlu

    2014-04-01

    Full Text Available The present paper reports on the spectral results pertaining to Sm3+ or Dy3+ (0.2 mol% ions doped B2O3-ZnO-MgO (BZM glasses. The amorphous nature of the reference glass (65B2O3-20ZnO-15MgO has been confirmed from its XRD measurement. Thermal analysis has been carried out for the precursor chemical mix and its weight loss has been noticed from the TG profile. Based on the DTA profile, the precursor chemicals mix transition temperature (Tg and crystallization temperature (Tc have been identified. The transformation of trigonal BO3 units into tetrahedral BO4 units has evidenced from the Fourier transform infrared (FTIR spectrum of reference glass without dopant ion(s. Spectral measurements of absorption, excitation, emission and emission transition lifetimes have been carried out for the Sm3+ and Dy3+ ions containing BZM glasses separately. These glasses exhibit strong intense absorption bands in the near-infrared (NIR region. The emission spectrum of Sm3+ : BZM glass shows a prominent and bright orange-red emission at 602 nm ( 4G5/2 6H7/2 upon excitation with λexci = 404 nm (6H5/24 F7/2. In the case of Dy3+: BZM glass, an appreciable blue emission at 485 nm (4 F9/26H15/2 has been identified with an excitation at λexci = 387 nm ( 6H15/24 I13/2. Energy level schemes relating to the emission mechanisms involved both in Sm3+ and Dy3+ glasses have also been explained. Decay curves are have been plotted in order to evaluate emission band lifetimes.

  6. Influences of CaO on Crystallization, Microstructures, and Properties of BaO-Al2O3-B2O3-SiO2 Glass-Ceramics

    Science.gov (United States)

    Li, Bo; Tang, Bo; Xu, Mingjiang

    2015-10-01

    We have developed BaO-CaO-Al2O3-B2O3-SiO2 glass-ceramics with high thermal coefficient of expansion (TCE) to overcome thermal mismatch at board level. The crystalline phases include quartz (major), cristobalite (minor), and bazirite BaZrSi3O9 (minor). Calculations from whole-pattern fitting show that the crystallinity varies slightly within the range of 33.48% to 34.89%, while the mass fraction of the phases changes remarkably with the CaO content. This indicates that CaO cannot promote crystallization of Ba-Al-B-Si glass, but effectively suppresses the phase transformation from quartz to cristobalite, making the thermal expansion curves linear. An empirical equation for the TCE versus the temperature and the amount of CaO is established. Furthermore, the densification mechanism of Ca modifiers is revealed. Due to its higher field strength than Ba, substitution of Ca increases the glass viscosity and inhibits ion diffusion. Excessive CaO is thus harmful to the density, bending strength, and electrical properties. The sample with 10 wt.% CaO sintered at 950°C exhibited high bending strength (154.1 MPa) and high TCE (12.38 ppm/°C) as well as good electrical properties ( ɛ = 6.2, tan δ = 5 × 10-4, ρ = 3.8 × 1012 Ω cm).

  7. The content of chromium and copper in plants and soil fertilized with sewage sludge with addition of various amounts of CaO and lignite ash

    Directory of Open Access Journals (Sweden)

    Wysokiński Andrzej

    2016-09-01

    Full Text Available The influence of fertilization with fresh sewage sludge with the addition of calcium oxide and lignite ash in the proportions dry mass 6:1, 4:1, 3:1 and 2:1 on the content of chromium and copper in plants and soil and uptake of these elements was investigated in pot experiment. Sewage sludge were taken from Siedlce (sludge after methane fermentation and Łuków (sludge stabilized in oxygenic conditions, eastern Poland. The chromium content in the biomass of the test plants (maize, sunflower and oat was higher following the application of mixtures of sewage sludge with ash than of the mixtures with CaO. The copper content in plants most often did not significantly depend on the type of additives to the sludge. Various amounts of additives to the sewage sludge did not have a significant effect on the contents of either of the studied trace elements in plants. The contents of chromium and copper in soil after 3 years of cultivation of plants were higher than before the experiment, but these amounts were not significantly differentiated depending on the type and the amount of the used additive (i.e. CaO vs. ash to sewage sludge.

  8. Performance and economic assessments of a solid oxide fuel cell system with a two-step ethanol-steam-reforming process using CaO sorbent

    Science.gov (United States)

    Tippawan, Phanicha; Arpornwichanop, Amornchai

    2016-02-01

    The hydrogen production process is known to be important to a fuel cell system. In this study, a carbon-free hydrogen production process is proposed by using a two-step ethanol-steam-reforming procedure, which consists of ethanol dehydrogenation and steam reforming, as a fuel processor in the solid oxide fuel cell (SOFC) system. An addition of CaO in the reformer for CO2 capture is also considered to enhance the hydrogen production. The performance of the SOFC system is analyzed under thermally self-sufficient conditions in terms of the technical and economic aspects. The simulation results show that the two-step reforming process can be run in the operating window without carbon formation. The addition of CaO in the steam reformer, which runs at a steam-to-ethanol ratio of 5, temperature of 900 K and atmospheric pressure, minimizes the presence of CO2; 93% CO2 is removed from the steam-reforming environment. This factor causes an increase in the SOFC power density of 6.62%. Although the economic analysis shows that the proposed fuel processor provides a higher capital cost, it offers a reducing active area of the SOFC stack and the most favorable process economics in term of net cost saving.

  9. [Textual research on Guang dong xin yu (New Sayings of Guangdong) quoted in Ben cao gang mu shi yi (Supplements to Compendium of Materia Medica].

    Science.gov (United States)

    Zhang, Ruixian; Zhang, Wei; Li, Jian; Liang, Fei

    2014-05-01

    Altogether 15 terms for Guang dong xin yu (New Sayings of Guangdong) were used in Ben cao gang mu shi yi (Supplements to Compendium of Materia Medica), including Yue yu (Cantonese sayings), Chong yu (Sayings from Insect Drug), Jie yu (Sayings from Crustacean Drug), Xin yu (New Sayings), Yue hai xiang yu (Fragrant Sayings from Cantonese Region), Yue zhi mu yu (Sayings from Plants in Cantonese Annals), Guang dong suo yu (Trivial Sayings from Guangdong), Yue shan lu (Records of Cantonese Mountains), Yue lu (Cantonese Records), Jiao guang lu (Joint Guangdong Records), Yue cao zhi (Records of Cantonese Grasses), Guang guo lu (Records of Guangdong Fruits), Nan yue suo ji (Trivial Records of Southern Canton), Guang zhi (Guangdong Records), Yue zhi (Cantonese Records) etc. dealing with 57 sorts of drugs (with individual overlapping ones), the author of Xin yu was Qu Dajun, a surviving fogy of the Ming Dynasty actively involved in the activities to restore the old dynasty and resist the Qing Dynasty, and was persecuted in the literary inquisition in which his works were burnt so that Zhao Xuemin, when quoting his texts, had to go in a roundabout way.

  10. Factors Influencing MgO Content of RE-Mg Nodularizing Alloy%REMg球化剂中MgO含量的影响因素

    Institute of Scientific and Technical Information of China (English)

    杨宇鹏; 肖勇

    2013-01-01

    The effect of Mg in nodularizing alloy was introduced.When the total content of Mg was constant,the formation of MgO reduced the content of the effective Mg that would influence the nodularizing capability of the nodualrizing alloy.The source of MgO in nodularizing alloy was analyzed as follows:the MgO formed during the melting process of the nodularizing alloy and the MgO formed during the analysis sample preparing process.It was pointed out after analyzing two cases:(1) the MgO content of nodularizing alloy is the main factor influencing its nodularzing capability,therefore the MgO content should be reduced by improving its melting process; (2)In order to ensure the veracity of MgO content test it's necessary to use correct sample preparing method.%介绍了Mg在球化剂中的作用.当w(Mg总)一定时,MgO的生成降低了w(Mg有效)的含量,影响到球化剂的球化能力.分析了球化剂中MgO的来源:球化剂熔炼过程中产生MgO、在制取分析样品过程中产生MgO.通过2个案例的分析,指出:(1)球化剂中MgO含量的高低是影响其球化能力的主要因素,应通过改进熔炼工艺来降低w(MgO)量;(2)为确保球化剂中w(MgO)量检测的准确性,应采用正确的样品制备方法.

  11. GEMAS: Distribution of major elements in Polish agricultural soil

    Science.gov (United States)

    Dusza-Dobek, Aleksandra; Pasieczna, Anna; Kwecko, Paweł

    2014-05-01

    Amount and quality of produced food is highly dependent on soil chemical properties and composition. The GEMAS project (Geochemical Mapping of Agricultural and Grazing Land Soil of Europe) has provided new homogeneous geochemical data for Polish agricultural soils. This study presents the distribution of common major elements such as CaO, MgO, Fe2O3, Al2O3, K2O, Na2O, SiO2, determined in 129 samples of agricultural soil of Poland. The total element concentrations obtained by X-ray fluorescence spectroscopy (XRF) were compared with the results from aqua regia acid digestion determined by ICP-MS. The distribution patterns of selected major elements reveal two major geochemical provinces - the northern province and the southern province, distinguished with respect to the natural geochemical background and resulting from the geological evolution of the region. The soil of the northern province (Polish Lowland), dominated by glacial deposits, show low contents of CaO, MgO, Fe2O3, Al2O3, K2O, Na2O, and high contents of SiO2. High silica content reflects the presence of sand-rich deposits which belong to the larger European feature with cover sands and loess of mainly Weichselian age and stretching from Ukraine to western Germany and Denmark. The southern province is characterised by high concentrations of almost all major elements (except SiO2). Soils in the Sudetes, Upper Silesia and the Carpathian Mountains developed in majority on pre-Quaternary rocks. In the Sudetes, soil formed on magmatic and metamorphic rocks of Paleozoic age. In the Carpathians and Upper Silesia, the flysch and molasse formations containing various material of magmatic and sedimentary origin constitute the immediate substratum of soil.

  12. Sampling and major element chemistry of the recent (A.D. 1631-1944) Vesuvius activity

    Science.gov (United States)

    Belkin, H.E.; Kilburn, C.R.J.; de Vivo, B.

    1993-01-01

    Detailed sampling of the Vesuvius lavas erupted in the period A.D. 1631-1944 provides a suite of samples for comprehensive chemical analyses and related studies. Major elements (Si, Ti, Al, Fetotal, Mn, Mg, Ca, Na, K and P), volatile species (Cl, F, S, H2O+, H2O- and CO2), and ferrous iron (Fe2+) were determined for one hundred and forty-nine lavas and five tephra from the A.D. 1631-1944 Vesuvius activity. The lavas represent a relatively homogeneous suite with respect to SiO2, TiO2, FeOtotal, MnO and P2O5, but show systematic variations among MgO, K2O, Na2O, Al2O3 and CaO. The average SiO2 content is 48.0 wt.% and the rocks are classified as tephriphonolites according to their content of alkalis. All of the lavas are silica-undersaturated and are nepheline, leucite, and olivine normative. There is no systematic variation in major-element composition with time, over the period A.D. 1631-1944. The inter-eruption and intra-eruption compositional differences are the same magnitude. The lavas are highly porphyritic with clinopyroxene and leucite as the major phases. Fractionation effects are not reflected in the silica content of the lavas. The variability of MgO, K2O, Na2O, and CaO can be modelled as a relative depletion or accumulation of clinopyroxene. ?? 1993.

  13. Effect of CeO2 and CaO Promoters on Ignition Performance for Partial Oxidation of Methane over Ni/MgO-Al2O3 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Yejun Qiu; Jixiang Chen; Jiyan Zhang

    2007-01-01

    The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane (POM) to synthesis gas was investigated. It was found that the POM reaction could not be ignited over 1wt%Ni/MgO-Al2O3 catalyst without the promoters in the temperature range from 773 K to 1073 K. CeO2 and CaO promoters enhanced the ignition performance and the POM reactivity of 1wt%Ni/MgO-Al2O3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactionconditions. The modification effects of CeO2 and CaO promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species.

  14. The Effect of Calcination Temperatures on the Activity of CaO and CaO/SiO2 Heterogeneous Catalyst for Transesterification of Rubber Seed Oil in the Presence of Coconut Oil as A Co-Reactant

    Directory of Open Access Journals (Sweden)

    Kamisah D. Pandiangan

    2016-12-01

    Full Text Available This study was carried out to examine the potential of conversion of rubber seed oil into biodiesel. A series experiments was conducted using CaO and CaO/SiO2 as catalyst and coconut oil as co-reactant, with the main purpose to assess the effect of calcination temperatures on the performance of the catalysts. The results obtained demonstrate that the use of coconut oil as co-reactant significantly promoted conversion of fatty acids in rubber seed oil into their corresponding methylesters. It was also found that the catalytic activity of both CaO and CaO/SiO2 was significantly influenced by calcination temperatures and at the same temperature, CaO/SiO2 exhibited higher activity than unsupported CaO. The highest yield was achieved using CaO/SiO2catalyst subjected to calcination at 800 oC

  15. Structure and properties of the slags of continuous converting of copper nickel-containing mattes and concentrates: II. Effect of the SiO2/CaO ratio on the structure and liquidus temperature of the slags

    Science.gov (United States)

    Pigarev, S. P.; Tsymbulov, L. B.; Selivanov, E. N.; Chumarev, V. M.

    2012-03-01

    The structure and liquidus temperature of the SiO2-CaO-Al2O3-FeO x -Cu2O-NiO slags that form during continuous converting of copper mattes and concentrates into blister copper are analyzed. The slag melt compositions are varied over a wide SiO2/CaO range. The slags are studied by X-ray diffraction, scanning electron microscopy, and electron-probe microanalysis. The liquidus temperature of the slags is determined by differential thermal analysis. It is found that, depending on the SiO2/CaO ratio, the structure and liquidus temperature of the slags change and the forms of copper in a slag also change. The SiO2/CaO range in a slag is recommended for the process of continuous converting of a copper nickel-containing sulfide raw materials.

  16. Large enhancement of magnetoresistance in NiFe film with MgO layers sandwiched after annealing

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhi-Duo; Li, Ming-Hua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Zhao, Chong-Jun, E-mail: zhaocj@bj-nmc.cn [Beijing Nmc Co., Ltd., Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Yang, Guang; Zhang, Jing-Yan; Jiang, Shao-Long; Zhao, Yun-Chi; Cui, Xiao-Peng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2014-12-01

    Highlights: • Ta/MgO/Ni{sub 81}Fe{sub 19}/MgO/Ta and Ta/Ni{sub 81}Fe{sub 19}/Ta were prepared by magnetron sputtering. • The electronic transport properties were studied. • The microstructure of NiFe film (100 nm) with MgO sandwiched was measured by HRTEM. • The average grain size and the crystallinity were determined from X-ray diffraction studies. • Δρ and ρ for samples as function of the NiFe thickness were analyzed. - Abstract: A large enhancement of magnetoresistance (MR) up to 6.0% has been observed in NiFe sandwiched by MgO layers, which is 50% larger than the highest MR (4%) in bulk materials. The great improvement of MR derives from the slight increase in corresponding resistivity change Δρ and the great decrease in resistivity ρ. The enhancement of Δρ is attributed to the strengthened spin-dependent scattering of the interfacial conductive electrons but the contribution will be slight with the increase in NiFe thickness. The main contribution is from the significant decrease in ρ, originating from confinement effect on electrons from well-formed oxide/metal interfaces after annealing. Surprisingly, this effect still exists when the NiFe thickness reaches 100 nm. Meanwhile, the oxide (MgO) layers inserted prevents the atomic interdiffusion of Ta and NiFe at the interfaces, which decreases the thickness of magnetic dead layer.

  17. Comparing van der Waals DFT methods for water on NaCl(001) and MgO(001).

    Science.gov (United States)

    Kebede, Getachew G; Spångberg, Daniel; Mitev, Pavlin D; Broqvist, Peter; Hermansson, Kersti

    2017-02-14

    In this work, a range of van der Waals type density functionals are applied to the H2O/NaCl(001) and H2O/MgO(001) interface systems to explore the effect of an explicit dispersion treatment. The functionals we use are the self-consistent vdW functionals vdW-DF, vdW-DF2, optPBE-vdW, optB88-vdW, optB86b-vdW, and vdW-DF-cx, as well as the dispersion-corrected PBE-TS and PBE-D2 methods; they are all compared with the standard PBE functional. For both NaCl(001) and MgO(001), we find that the dispersion-flavoured functionals stabilize the water-surface interface by approximately 20%-40% compared to the PBE results. For NaCl(001), where the water molecules remain intact for all overlayers, the dominant contribution to the adsorption energy from "density functional theory dispersion" stems from the water-surface interactions rather than the water-water interactions. The optPBE-vdW and vdW-DF-cx functionals yield adsorption energies in good agreement with available experimental values for both NaCl and MgO. To probe the strengths of the perturbations of the adsorbed water molecules, we also calculated water dipole moments and found an increase up to 85% for water at the MgO(001) surface and 70% at the NaCl(001) surface, compared to the gas-phase dipole moment.

  18. Dietary Supplementation of Magnesium Oxide (MgO) Nanoparticles for Better Survival and Growth of the Freshwater Prawn Macrobrachium rosenbergii Post-larvae.

    Science.gov (United States)

    Srinivasan, Veeran; Bhavan, Periyakali Saravana; Rajkumar, Gopalan; Satgurunathan, Thangavelu; Muralisankar, Thirunavukkarasu

    2016-10-05

    This study was performed to assess the growth-promoting potential of dietary magnesium oxide nanoparticles (MgO NPs) in Macrobrachium rosenbergii post-larvae (PL). MgO NPs were supplemented at 0, 100, 200, 300, 400 and 500 mg kg(-1) with the basal diet (containing 0.95 g Mg kg(-1)); the concentrations of Mg in MgO NP-supplemented diets were increased correspondingly (1.07, 1.15, 1.24, 1.37 and 1.46 g Mg kg(-1) respectively). MgO NP-supplemented diets were fed to M. rosenbergii PL (initial weight 0.11 ± 0.04 g) for a period of 90 days. In the carcasses of experimental prawns, the content of Mg was found to be elevated significantly with respect to the individual diet (102.14, 183.29, 205.46, 221.03, 237.10 and 254.36 μg Mg g(-1) respectively) when compared with that of the control. The contents of Cu, Zn, Fe, Ca, Na and K levels were also found to be elevated in the carcasses of experimental prawns. Significant (P MgO NP-supplemented-feed-fed PL. There were no significant elevations recorded in activities of antioxidant enzymes [superoxide dismutase (SOD) and catalase (CAT)], lipid peroxidation (LPO) and metabolic enzymes [glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT)] recorded in any of the MgO NP-supplemented-feed-fed PL when compared with the control. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed increases in the staining intensity of polypeptide bands resolved in 500 mg kg(-1) MgO NP-supplemented-feed-fed PL when compared with the control. Based on the gradual improvement in attaining survival, growth, FCR, biochemical constituents and haemocyte population, this study recommends MgO NP supplementation of 500 mg kg(-1) for sustainable maintenance of M. rosenbergii PL. As the studied highest concentration of MgO NPs showed the best performance, it is necessary to study with beyond 500 mg kg(-1) of MgO NPs to optimize the actual concentration.

  19. The effect of translational energy on collision-induced dissociation of highly excited NO 2 on MgO(100)

    Science.gov (United States)

    Arnold, D. W.; Korolik, M.; Wittig, C.; Reisler, H.

    1998-01-01

    Collision-induced dissociation of highly excited NO 2 (i.e., mixed 2B 2/ 2A 1 molecular eigenstates just below D0) impinging on MgO(100) surfaces has been studied as a function of NO 2 internal excitation at an incident translational energy of 4400 cm -1 by using state-selective NO detection. NO internal energy distributions as well as the average energy transferred per activating collision have been obtained. The results, in particular the NO [ 2Π 1/2]/[ 2Π 3/2] population ratios, indicate the presence of exit-channel interactions with the surface that are dependent on collision energy.

  20. Temperature programmed desorption and infrared spectroscopic studies of thin water films on MgO(1 0 0)

    Science.gov (United States)

    Hawkins, S.; Kumi, G.; Malyk, S.; Reisler, H.; Wittig, C.

    2005-03-01

    Thin water (D 2O) films on MgO(1 0 0) surfaces have been studied. Water was deposited at 115 K and monolayer and multilayer films were prepared by annealing above 150 K, where the transition from amorphous solid to cubic ice is known to take place, and then re-cooling. Temperature programmed desorption traces and transmission Fourier transform infrared spectra were recorded. For the monolayer, results are consistent with an essentially flat, hydrogen-bonded water network without a significant amount of dangling OD. Ice growing on the monolayer appears to be a blend of amorphous and crystalline solid at 115 K, becoming more crystalline when annealed.