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

1994-12-31

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

24 CFR 982.602 - SRO: Who may reside in an SRO?

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false SRO: Who may reside in an SRO? 982... URBAN DEVELOPMENT SECTION 8 TENANT BASED ASSISTANCE: HOUSING CHOICE VOUCHER PROGRAM Special Housing Types Single Room Occupancy (sro) § 982.602 SRO: Who may reside in an SRO? A single person may reside in...

Destructive Adsorption of Carbon Tetrachloride on Alkaline Earth Metal Oxides

NARCIS (Netherlands)

Weckhuysen, B.M.; Mestl, Gerhard; Rosynek, Michael P.; Krawietz, Thomas R.; Haw, James F.; Lunsford, Jack H.

1998-01-01

The destructive adsorption of CCl4 on MgO, CaO, SrO, and BaO has been studied as a function of the reaction temperature and the amount of CCl4 injected. The reaction was followed using in situ Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and 13 C

THEORETICAL-ANALYSIS OF THE O(1S) BINDING-ENERGY SHIFTS IN ALKALINE-EARTH OXIDES - CHEMICAL OR ELECTROSTATIC CONTRIBUTIONS

NARCIS (Netherlands)

PACCHIONI, G; BAGUS, PS

1994-01-01

We report results from ab initio cluster-model calculations on the O(1s) binding energy (BE) in the alkaline-earth oxides, MgO, CaO, SrO, and BaO; all these oxides have a cubic lattice structure. We have obtained values for both the initial- and final-state BE's. A simple point-charge model, where

Preliminary Reports, Memoranda and Technical Notes of the Materials Research Council Summer Conference, La Jolla, CA

Science.gov (United States)

1975-07-01

NOT WITH POSITRON ANNIHILATION 3:35 COFFEE BREAK SESSION VIII - RESIDUAL STRESSES 3:45 MEASUREMENT OF SURFACE STRAINS BY SURFACE REFLECTION...10 — S’ -2 8 a. — CaO^^ MgO CD 6 — ^<SrO o. 4 £ 2 : . ^^•BOO n ^f I 1 1 1 1 1 1 l_ 20 . > o. o o...Hardness and Fracture Toughness Data for the Materials Used in the Sawing Study by Rice and Speronello i i Material B.C Si3N4 Al 0, 2 i Zr02 MgO

Microstructure of epitaxial SrRuO 3 thin films on MgO substrates

Science.gov (United States)

Ai, Wan Yong; Zhu, Jun; Zhang, Ying; Li, Yan Rong; Liu, Xing Zhao; Wei, Xian Hua; Li, Jin Long; Zheng, Liang; Qin, Wen Feng; Liang, Zhu

2006-09-01

SrRuO 3 thin films have been grown on singular (1 0 0) MgO substrates using pulsed laser deposition (PLD) in 30 Pa oxygen ambient and at a temperature of 400-700 °C. Ex situ reflection high-energy electron diffraction (RHEED) as well as X-ray diffraction (XRD) θ/2 θ scan indicated that the films deposited above 650 °C were well crystallized though they had a rough surface as shown by atom force microscopy (AFM). XRD Φ scans revealed that these films were composed of all three different types of orientation domains, which was further confirmed by the RHEED patterns. The heteroepitaxial relationship between SrRuO 3 and MgO was found to be [1 1 0] SRO//[1 0 0] MgO and 45°-rotated cube-on-cube [0 0 1] SRO//[1 0 0] MgO. These domain structures and surface morphology are similar to that of ever-reported SrRuO 3 thin films deposited on the (0 0 1) LaAlO 3 substrates, and different from those deposited on (0 0 1) SrTiO 3 substrates that have an atomically flat surface and are composed of only the [1 1 0]-type domains. The reason for this difference was ascribed to the effect of lattice mismatch across the film/substrate interface. The room temperature resistivity of SrRuO 3 films fabricated at 700 °C was 300 μΩ cm. Therefore, epitaxial SrRuO 3 films on MgO substrate could serve as a promising candidate of electrode materials for the fabrication of ferroelectric or dielectric films.

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

NARCIS (Netherlands)

IJsselsteijn, R.P.J.; Terpstra, D.; Flokstra, Jakob; Rogalla, Horst

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

Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives

Science.gov (United States)

Abdelghany, A. M.; Ouis, M. A.; Azooz, M. A.; ElBatal, H. A.; El-Bassyouni, G. T.

2016-01-01

Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680 cm-1 after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content.

Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives.

Science.gov (United States)

Abdelghany, A M; Ouis, M A; Azooz, M A; ElBatal, H A; El-Bassyouni, G T

2016-01-05

Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680cm(-1) after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content. Copyright © 2015 Elsevier B.V. All rights reserved.

Single frequency intracavity SRO

DEFF Research Database (Denmark)

Abitan, Haim; Buchhave, Preben

2000-01-01

Summary form only given. A single resonance optical parametric oscillator (SRO) is inserted intracavity to a CW high power, single frequency, and ring Nd:YVO4 laser. We obtain a stable single frequency CW SRO with output at 1.7-1.9 μm (idler) and a resonating signal at 2.3-2.6 μm. The behavior...

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.

24 CFR 982.603 - SRO: Lease and HAP contract.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false SRO: Lease and HAP contract. 982... Types Single Room Occupancy (sro) § 982.603 SRO: Lease and HAP contract. For SRO housing, there is a separate lease and HAP contract for each assisted person. ...

Antibacterial characteristics of CaCO3-MgO composites

International Nuclear Information System (INIS)

Yamamoto, Osamu; Ohira, Toshiaki; Alvarez, Kelly; Fukuda, Masayuki

2010-01-01

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 3 grain, were fabricated by the thermal decomposition of dolomite. The composite obtained by heating at 800 deg. C consisted of CaCO 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.

Microstructural characteristics of low-temperature (1400°C sintered MgO obtained from seawater

Directory of Open Access Journals (Sweden)

Jakić Jelena

2017-01-01

Full Text Available The purpose of this study was to investigate the influence of a rinsing of Mg(OH2 precipitated from seawater by substoichiometric precipitation (80% precipitation and the addition of TiO2 on microstructural characteristics of the MgO obtained by sintering at low temperature (1400°C. The results of examination indicate that the method of rinsing of the magnesium hydroxide precipitate in the technological process of obtaining MgO from seawater significantly affects the chemical composition of samples, primarily with regard to the CaO and B2O3 content. The samples were doped with TiO2 to improve the evaporation of B2O3 and sintering of MgO samples that were characterized by XRD and SEM/EDS. These techniques confirmed the high purity of MgO samples obtained and the formation of secondary compounds in very small quantities that have a positive effect on the densification.

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.

24 CFR 982.604 - SRO: Voucher housing assistance payment.

Science.gov (United States)

2010-04-01

... Types Single Room Occupancy (sro) § 982.604 SRO: Voucher housing assistance payment. (a) For a person... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false SRO: Voucher housing assistance payment. 982.604 Section 982.604 Housing and Urban Development Regulations Relating to Housing and Urban...

Study of structure and properties of oxide electrode materials (Fe3O4, AZO, SRO) and their device applications

Science.gov (United States)

Olga, Chichvarina

Ferroelectric thin film capacitor heterostructures have attracted considerable attention in the last decade because of their potential applications in piezoelectric sensors, actuators, power generators and non-volatile memory devices. Strongly correlated all-perovskite oxide heterojunctions are of a particular interest, as their material properties (electronic, structural, magnetic and optical, etc.) can be tuned via doping, interface effect, applied electrical field, and formation of two-dimensional electron gas (2DEG), etc. The right selection of electrode material for this type of capacitor-like structures may modify and enhance the performance of a device, as the electrode/barrier layer interfaces can significantly influence its macroscopic properties. Although there is a number of reports on the effect of electrode interfaces on the properties of PZT capacitors deposited on SRO buffered STO substrate, very little is known about Fe3O4/PZT and AZO/PZT electrode interfaces. This thesis comprises two parts. In the first part we present a systematic study of the structural, transport, magnetic and optical properties of oxide thin films: AZO, Fe3O4 and SRO. These monolayers were fabricated via pulsed laser deposition technique on quartz, MgO and STO substrates respectively. The second part of this thesis elucidates the behaviour of these three oxides as electrode components in PZT/SRO/STO heteroepitaxial structures. The highlights of the work are summarized below: 1) Zinc-blende (ZB) phase of ZnO was predicted to possess higher values of conductivity and higher doping efficiency compared to its wurzite counterpart and thus has greater chances of facilitating the fabrication of ZnO-electrode-based devices. However, zinc-blende is a metastable phase, and it is challenging to obtain single-phase ZB. To tackle this challenge we tuned parameters such-as film thickness, substrate and annealing effect, and achieved a ZB phase of Ti-doped ZnO, ZB-(Zn1-xTix)O thin film. An

Effect of SrO content on Zeolite Structure

Science.gov (United States)

Widiarti, N.; Sari, U. S.; Mahatmanti, F. W.; Harjito; Kurniawan, C.; Prasetyoko, D.; Suprapto

2018-04-01

The aims of current studies is to investigate the effect of strontium oxide content (SrO) on synthesized zeolite. Zeolite was synthesized from Tetraethyl orthosilicate (TEOS) as precursors of SiO2 and aluminum isopropoxide (AIP) precursors. The mixture was aged for 3 days and hydrothermally treated for 6 days. The SrO content was added by impregnation method. The products were then characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Surface Area Analyzer (SAA). The diffractogram confirmed the formation of Faujasite-like zeolite. However, after the addition of SrO, the crystallinity of zeolite was deformed. The diffractograms shows the amorphous phase of zeolite were decrease as the SrO content is increase. The structural changes was also observed from FTIR spectra which shows the shifting and peak formation. The surface area analysis showed that the increasing loading of SrO/Zeolites reduced the catalyst surface area.

Study of narrow and intense UV electroluminescence from ITO/SRO/Si-p and ITO/SRN/SRO/Si-p based light emitting capacitors

International Nuclear Information System (INIS)

Cabañas-Tay, S.A.; Palacios-Huerta, L.; Aceves-Mijares, M.; Coyopol, A.; Morales-Morales, F.; Pérez-García, S.A.; Licea-Jiménez, L.; Domínguez-Horna, C.; Monfil-Leyva, K.; Morales-Sánchez, A.

2017-01-01

In this work, multiple narrow and highly intense ultraviolet (UV) electroluminescent (EL) bands were observed in light emitting capacitors (LECs) using silicon rich oxide (SRO) films as active layer. Besides, the effect of a thin silicon rich nitride (SRN) film on top of the SRO (as SRN/SRO bilayer) layer was also studied. LECs were fabricated using simple metal–insulator–semiconductor (MIS) structures with indium tin oxide (ITO) and aluminum as gate and substrate electrodes, respectively. SRO and SRN films contain 41.85±1.1 and 46.96±1.1 at% of silicon, respectively. Both structures exhibited a resistance switching (RS) behavior from a high conduction state (HCS) to a low conduction state (LCS), enhancing an intense UV EL. This RS behavior produces structural changes in the active layer and probably in the ITO contact. Seven narrow bands with half-peak width of 7±0.6 nm at ~250, 270, 285, 305, 325, 415 and 450 nm were clearly observed once the LCS was reached. These bands could be related to a combination of emissions through defects inside SRO (252, 288.2 and 415 nm), and characteristic radiation of neutral tin (252.39 and 286.33 nm), neutral indium (271.02, 303.93 and 325.85 nm), single (444.82 nm) and doubly ionized indium (403.07 nm). Furthermore, red EL was observed at the HCS and it was similar to the PL spectra indicating the same radiative process involved. The charge transport is improved when the SRN/SRO bilayer is used as active layer in the LEC. An EL band at ~590 nm is observed when the SRN/SRO bilayer is formed at both conduction states. This band has been observed before and attributed to transitions from the minimum conduction band to K° centers in SRN films. The conduction mechanism responsible of the EL at both conduction states was also studied.

Study of narrow and intense UV electroluminescence from ITO/SRO/Si-p and ITO/SRN/SRO/Si-p based light emitting capacitors

Energy Technology Data Exchange (ETDEWEB)

Cabañas-Tay, S.A., E-mail: scabanastay@hotmail.com [Centro de Investigación en Materiales Avanzados S.C., Unidad Monterrey-PIIT, 66600, Apodaca, Nuevo León (Mexico); Palacios-Huerta, L.; Aceves-Mijares, M. [INAOE, Electronics Department, Apartado 51, Puebla 72000 (Mexico); Coyopol, A. [CIDS-BUAP, Apdo. 1651, Puebla Pue 72000 (Mexico); Morales-Morales, F.; Pérez-García, S.A.; Licea-Jiménez, L. [Centro de Investigación en Materiales Avanzados S.C., Unidad Monterrey-PIIT, 66600, Apodaca, Nuevo León (Mexico); Domínguez-Horna, C. [Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), Bellaterra, 08103, Barcelona (Spain); Monfil-Leyva, K. [CIDS-BUAP, Apdo. 1651, Puebla Pue 72000 (Mexico); Morales-Sánchez, A., E-mail: alfredo.morales@cimav.edu.mx [Centro de Investigación en Materiales Avanzados S.C., Unidad Monterrey-PIIT, 66600, Apodaca, Nuevo León (Mexico)

2017-03-15

In this work, multiple narrow and highly intense ultraviolet (UV) electroluminescent (EL) bands were observed in light emitting capacitors (LECs) using silicon rich oxide (SRO) films as active layer. Besides, the effect of a thin silicon rich nitride (SRN) film on top of the SRO (as SRN/SRO bilayer) layer was also studied. LECs were fabricated using simple metal–insulator–semiconductor (MIS) structures with indium tin oxide (ITO) and aluminum as gate and substrate electrodes, respectively. SRO and SRN films contain 41.85±1.1 and 46.96±1.1 at% of silicon, respectively. Both structures exhibited a resistance switching (RS) behavior from a high conduction state (HCS) to a low conduction state (LCS), enhancing an intense UV EL. This RS behavior produces structural changes in the active layer and probably in the ITO contact. Seven narrow bands with half-peak width of 7±0.6 nm at ~250, 270, 285, 305, 325, 415 and 450 nm were clearly observed once the LCS was reached. These bands could be related to a combination of emissions through defects inside SRO (252, 288.2 and 415 nm), and characteristic radiation of neutral tin (252.39 and 286.33 nm), neutral indium (271.02, 303.93 and 325.85 nm), single (444.82 nm) and doubly ionized indium (403.07 nm). Furthermore, red EL was observed at the HCS and it was similar to the PL spectra indicating the same radiative process involved. The charge transport is improved when the SRN/SRO bilayer is used as active layer in the LEC. An EL band at ~590 nm is observed when the SRN/SRO bilayer is formed at both conduction states. This band has been observed before and attributed to transitions from the minimum conduction band to K° centers in SRN films. The conduction mechanism responsible of the EL at both conduction states was also studied.

Study for obtaining a suppressor device of transients using the Al/SRO/Si structure; Estudio para la obtencion de un dispositivo supresor de transitorios utilizando la estructura Al/SRO/Si

Energy Technology Data Exchange (ETDEWEB)

Marin Ramos, Heriberto

1999-06-01

The circuits and electronic equipment use protective devices against voltage transients. In this work the Aluminium/Oxide structure rich in Silicon/Silicon is presented as another option in the field of transient suppressors devices. Some devices used in the suppression of voltage transients are: zinc oxide varistors, of silicon carbide varistors, selenium cells, and Zener diodes. The Al/SRO/Si structure presents conductive properties due to the presence of excess Silicon in the SRO film. Varying the reacting gases ratio (Ro=N{sub 2}O/SiH{sub 4}) during the growth of the film of Oxide Rich in Silicon (SRO), the conductivity of the material can be varied. The SRO turns out to be of great importance for the suppressor device of transients device that is pretended to be obtained in the present work due to its non-ohmic behavior. The Al/SRO/Si device behaves of several ways depending on the characteristics of the SRO and the silicon substrate. It has been found that one of these behaviors is as a of voltage transients suppressor. Verifying its behavior as transient suppressor, the effects of the film thickness, the area and the excess of silicon of the device were studied, for this purpose the characteristic I-V was obtained, and the obtention of some parameters in DC. In the present work the SRO was obtained by means of LPCVD (Low Pressure Chemical Vapor Deposition), initially a C-V characterization was made to obtain an indicative parameter of excess silicon, such as: permittivity of the SRO film. Also, the refraction index was obtained, which is an indicative parameter of the presence of excess Silicon. Once having the certainty of the presence of excess silicon it was proceed to obtain the I-V characteristic of the Al/SRO/Si structure as a device. The behavior of the Al/SRO/Si structure was analyzed with different parameters, such as: Ro, thickness of the SOR, areas. [Spanish] Los circuitos y equipos electronicos utilizan dispositivos de proteccion contra

Older Women in Single Room Occupant (SRO) Hotels: A Seattle Profile.

Science.gov (United States)

Lally, Maureen; And Others

1979-01-01

Life histories and daily routines of women over the age of 55 living in Seattle single room occupant (SRO) hotels were studied using observational and interviewing methods. Residence in SRO's appears to be part of a natural life history progression for these women rather than a result of social pathology. (Author)

Phase equilibria in the system As2-O5 - SrO

International Nuclear Information System (INIS)

Kasenov, B.K.; Ashlyaeva, I.V.

1993-01-01

T-x phase state diagram of As 2 O 5 -SrO system was investigated by the methods of physicochemical analysis. It was established that incongruently melting Sr(AsO 3 ) 2 (t mel 900 deg C), Sr 2 As 2 O 4 (t mel = 1140 deg C), Sr 4 As 2 O 9 (t mel = 1390 deg C) and congruently melting at 1635 deg C Sr 3 (AsO 4 ) 2 formed in the system. Eutectic points were revealed in the system: As 2 O 5 -Sr(AsO 3 ) 2 (15.0 mol % SrO, 700 deg C) and Sr 3 (AsO 4 ) 2 -Sr 4 As 2 O 9 (78 mol % SrO, 1370 deg C)

Decomposition pathways of polytetrafluoroethylene by co-grinding with strontium/calcium oxides.

Science.gov (United States)

Qu, Jun; He, Xiaoman; Zhang, Qiwu; Liu, Xinzhong; Saito, Fumio

2017-06-01

Waste polytetrafluoroethylene (PTFE) could be easily decomposed by co-grinding with inorganic additive such as strontium oxide (SrO), strontium peroxide (SrO 2 ) and calcium oxide (CaO) by using a planetary ball mill, in which the fluorine was transformed into nontoxic inorganic fluoride salts such as strontium fluoride (SrF 2 ) or calcium fluoride (CaF 2 ). Depending on the kind of additive as well as the added molar ratio, however, the reaction mechanism of the decomposition was found to change, with different compositions of carbon compounds formed. CO gas, the mixture of strontium carbonate (SrCO 3 ) and carbon, only SrCO 3 were obtained as reaction products respectively with equimolar SrO, excess SrO and excess SrO 2 to the monomer unit CF 2 of PTFE were used. Excess amount of CaO was needed to effectively decompose PTFE because of its lower reactivity compared with strontium oxide, but it promised practical applications due to its low cost.

Analýza sortimentu firmy SkyTech Corporation s.r.o.

OpenAIRE

Dvořáková, Šárka

2017-01-01

This thesis focuses on small company SkyTech Corporation s.r.o, which distributes products from the field of cosmetic, decorative cosmetic, cosmetic accessories and make-up brushes. The first part is theoretical and serves as basis for elaboration of the practical part. Theoretical part focus on marketing mix, competition, assortment and analysis connected with them. In practical part SkyTech Corporaton s.r.o. is introduced. Than follows the evaluation of individual brands and their roles in ...

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.

Physical and chemical properties of MgO ceramics treated in molten K2SO4 for a long period

International Nuclear Information System (INIS)

Iwasa, Mikio; Kose, Saburo; Korenaga, Sadayoshi; Furukawa, Mitsuhiko.

1978-01-01

The wall materials of MHD power generating channel are exposed to thermally, physically and chemically severe conditions, so that they have to withstand great damages, especially the attack of seed materials. Several kinds of ceramics proposed as the wall materials have been tested in the simulated MHD environment. In this paper, MgO ceramics were treated in molten K 2 SO 4 , a typical seed material, and the changes in their physical and chemical properties were investigated in comparison with those of Al 2 O 3 ceramics. four kinds of MgO ceramics, three sintered and one electric fused, were immersed in molten K 2 SO 4 at 1300 0 C for the periods up to 1000 h, and weight, volume, surface roughness, bending strength and hardness were measured. The changes in the microstructures and chemical compositions due to the K 2 SO 4 treatment were also investigated. MgO ceramics were attacked by molten K 2 SO 4 only at the grain boundaries on the surface, in contrast at Al 2 O 3 ceramics which were severely damaged to form β-Al 2 O 3 . It was found that SiO 2 and CaO in the grain boundaries had played important roles to the attack of K 2 SO 4 . Generally, the changes in the properties of MgO ceramics by the K 2 SO 4 treatment were very small compared with those of Al 2 O 3 ceramics. It was concluded that MgO ceramics are more stable than Al 2 O 3 ceramics in molten K 2 SO 4 and their properties do not show substantial drops for long periods. (author)

Thermodynamic properties of some metal oxide-zirconia systems

Science.gov (United States)

Jacobson, Nathan S.

1989-01-01

Metal oxide-zirconia systems are a potential class of materials for use as structural materials at temperatures above 1900 K. These materials must have no destructive phase changes and low vapor pressures. Both alkaline earth oxide (MgO, CaO, SrO, and BaO)-zirconia and some rare earth oxide (Y2O3, Sc2O3, La2O3, CeO2, Sm2O3, Gd2O3, Yb2O3, Dy2O3, Ho2O3, and Er2O3)-zirconia system are examined. For each system, the phase diagram is discussed and the vapor pressure for each vapor species is calculated via a free energy minimization procedure. The available thermodynamic literature on each system is also surveyed. Some of the systems look promising for high temperature structural materials.

Society of the Alone: Freedom, Privacy, and Utilitarianism as Dominant Norms in the SRO

Science.gov (United States)

Stephens, Joyce

1975-01-01

The social world of the aged SRO tenant is described and analyzed. Characteristic features include an impoverishment of social roles and relationships which result in a "world of strangers." Dominant norms of SRO life which preclude the establishment of intimacy are examined; these include prescriptive norms of privacy, freedom, and…

Society of the alone: Freedom, Privacy and Utilitarianism as dominant norms in the SRO.

Science.gov (United States)

Stephens, J

1975-03-01

The social world of the aged SRO tenant is described and analyzed. Charteristic features include an impoverishment of social roles and relationships which result in a "world of strangers". Dominant norms of SRO life which preclude the establishment of intimacy are examined; these include prescriptive norms of privacy, freedom, and utilitarianism

Finanční analýza PENNY Market, s.r.o.

OpenAIRE

Šubrt, Jan

2015-01-01

This bachelor's thesis deals with financial analysis of Penny Market, s.r.o. in the period of 2011-2014. The work consists of two parts. The theoretical part is devoted to the core of financial analysis, its users, methods and individual ratio indicators. The practical part focuses on presentation of company Penny Market, s.r.o. and then on financial analysis itself. The analysis is based on horizontal and vertical analysis of financial statements and on calculation of profitability, liquidit...

Dolomite decomposition under CO2

International Nuclear Information System (INIS)

Guerfa, F.; Bensouici, F.; Barama, S.E.; Harabi, A.; Achour, S.

2004-01-01

Full text.Dolomite (MgCa (CO 3 ) 2 is one of the most abundant mineral species on the surface of the planet, it occurs in sedimentary rocks. MgO, CaO and Doloma (Phase mixture of MgO and CaO, obtained from the mineral dolomite) based materials are attractive steel-making refractories because of their potential cost effectiveness and world wide abundance more recently, MgO is also used as protective layers in plasma screen manufacture ceel. The crystal structure of dolomite was determined as rhombohedral carbonates, they are layers of Mg +2 and layers of Ca +2 ions. It dissociates depending on the temperature variations according to the following reactions: MgCa (CO 3 ) 2 → MgO + CaO + 2CO 2 .....MgCa (CO 3 ) 2 → MgO + Ca + CaCO 3 + CO 2 .....This latter reaction may be considered as a first step for MgO production. Differential thermal analysis (DTA) are used to control dolomite decomposition and the X-Ray Diffraction (XRD) was used to elucidate thermal decomposition of dolomite according to the reaction. That required samples were heated to specific temperature and holding times. The average particle size of used dolomite powders is 0.3 mm, as where, the heating temperature was 700 degree celsius, using various holding times (90 and 120 minutes). Under CO 2 dolomite decomposed directly to CaCO 3 accompanied by the formation of MgO, no evidence was offered for the MgO formation of either CaO or MgCO 3 , under air, simultaneous formation of CaCO 3 , CaO and accompanied dolomite decomposition

Demonstration of the CDMA-mode CAOS smart camera.

Science.gov (United States)

Riza, Nabeel A; Mazhar, Mohsin A

2017-12-11

Demonstrated is the code division multiple access (CDMA)-mode coded access optical sensor (CAOS) smart camera suited for bright target scenarios. Deploying a silicon CMOS sensor and a silicon point detector within a digital micro-mirror device (DMD)-based spatially isolating hybrid camera design, this smart imager first engages the DMD starring mode with a controlled factor of 200 high optical attenuation of the scene irradiance to provide a classic unsaturated CMOS sensor-based image for target intelligence gathering. Next, this CMOS sensor provided image data is used to acquire a focused zone more robust un-attenuated true target image using the time-modulated CDMA-mode of the CAOS camera. Using four different bright light test target scenes, successfully demonstrated is a proof-of-concept visible band CAOS smart camera operating in the CDMA-mode using up-to 4096 bits length Walsh design CAOS pixel codes with a maximum 10 KHz code bit rate giving a 0.4096 seconds CAOS frame acquisition time. A 16-bit analog-to-digital converter (ADC) with time domain correlation digital signal processing (DSP) generates the CDMA-mode images with a 3600 CAOS pixel count and a best spatial resolution of one micro-mirror square pixel size of 13.68 μm side. The CDMA-mode of the CAOS smart camera is suited for applications where robust high dynamic range (DR) imaging is needed for un-attenuated un-spoiled bright light spectrally diverse targets.

The CaO orange system in meteor spectra

Science.gov (United States)

Berezhnoy, A. A.; Borovička, J.; Santos, J.; Rivas-Silva, J. F.; Sandoval, L.; Stolyarov, A. V.; Palma, A.

2018-02-01

The CaO orange band system was simulated in the region 5900-6300 Å and compared with the experimentally observed spectra of Benešov bolide wake. The required vibronic Einstein emission coefficients were estimated by means of the experimental radiative lifetimes under the simplest Franck-Condon approximation. A moderate agreement was achieved, and the largest uncertainties come from modeling shape of FeO orange bands. Using a simple model the CaO column density in the wake of the Benešov bolide at the height of 29 km was estimated as (5 ± 2) × 1014 cm-2 by a comparison of the present CaO spectra with the AlO bands nicely observed at 4600-5200 Å in the same spectrum. The obtained CaO content is in a good agreement with the quenching model developed for the impact-produced cloud, although future theoretical and experimental studies of both CaO and FeO orange systems contribution would be needed to confirm these results.

Strong excitonic interactions in the oxygen K-edge of perovskite oxides.

Science.gov (United States)

Tomita, Kota; Miyata, Tomohiro; Olovsson, Weine; Mizoguchi, Teruyasu

2017-07-01

Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO 3 , SrTiO 3 , and BaTiO 3 , together with reference oxides, MgO, CaO, SrO, BaO, and TiO 2 , were investigated using a first-principles Bethe-Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti-O-Ti bonds. Copyright © 2016 Elsevier B.V. All rights reserved.

Motivácia zamestnancov v podniku Schwer Fittings, s.r.o., Martin

OpenAIRE

Badová, Andrea

2014-01-01

Badová, A., Employee motivation in the company Schwer Fittings, s.r.o., Martin. Bachelor thesis. Brno: Mendel University in Brno, 2013. This bachelor thesis is focused on employee motivation in Schwer Fittings, s.r.o., Martin. Main goal of this thesis is to evaluate current state of motivation system in this company and to suggest recommendations that can contribute to increase in employee motivation and to overall satisfaction. The theoretical part is based on literature mentioned in my work...

Analýza sortimentu společnosti Ford Motor Company s.r.o.

OpenAIRE

Bencová, Petra

2013-01-01

This thesis analyzes the products of Ford Motor Company s.r.o. which is a company operating on the Czech car market. The work is based on the theoretical knowledge described in the first part. The first part is followed by a practical section, in which I first describe the current market situation in the automotive industry in Czech Republic. Further I characterize the company Ford Motor Company s.r.o. itself, then I describe the most important car models and related market segments. Later in...

Marketingova strategie HPhobby s.r.o.

OpenAIRE

Tegzová, Milena

2011-01-01

This thesis deals with the marketing strategy of the company HPhobby s.r.o., which is realising its activities only through the online store www.hphobby.cz. The aim is to analyze the company and its competitors and apply this data to marketing strategy focused on Internet marketing tools. The first chapter deals with the analysis of the company and its competitors, for this chapter the SWOT, PEST analysis and BCG matrix are used. The second chapter concerns the segmentation of the consumer, f...

Elderly Single Room Occupancy (SRO) Hotel Tenants: Still Alone.

Science.gov (United States)

Rollinson, Paul A.

1991-01-01

Conducted study of single room occupancy (SRO) hotels in Chicago, Illinois and collected data on everyday experiences of 53 elderly tenants. Findings showed that hotel environments offered anything but independence. Residents were trapped in situation that exacerbated isolation and withdrawal from society and were in desperate need of social…

Le leggi del caos

CERN Document Server

Prigogine, Ilya

1993-01-01

Contro la concezione deterministica delle leggi di natura, teocratica e indifferente alla dimensione temporale, Prigogine riconosce nuova dignita al 'caos', la cui instabilità è fonte di disordine ma anche di ordine.

Effect of SrO on the electrical barrier formation and microstructure of TiO{sub 2} varistors

Energy Technology Data Exchange (ETDEWEB)

Delbrücke, Tiago, E-mail: tiagodt@gmail.com [Laboratory of Biomaterials & Advanced Ceramics, Engineering Materials Department, Federal University of Rio Grande do Sul, 91501-970, Porto Alegre, RS (Brazil); Pianaro, Sidnei A. [Interdisciplinary Laboratory of Ceramic Materials/LIMAC, Department of Materials Engineering, State University of Ponta Grossa, 84031-510, Ponta Grossa, PR (Brazil); Schmidt, Igor [Laboratory of Biomaterials & Advanced Ceramics, Engineering Materials Department, Federal University of Rio Grande do Sul, 91501-970, Porto Alegre, RS (Brazil); Cava, Sergio [Advanced Crystal Growth and Photonics, Technology Development Center, Federal University of Pelotas, 96010-900, Pelotas, RS (Brazil); Jurado, Jose R.; Sousa, Vânia C. [Laboratory of Biomaterials & Advanced Ceramics, Engineering Materials Department, Federal University of Rio Grande do Sul, 91501-970, Porto Alegre, RS (Brazil)

2016-12-01

TiO{sub 2}-based varistor materials with SrO dopants were prepared by the mechanical mixed oxides synthesis technique using conventional sintering at 1400 °C. I−V and microstructural characterization were performed. The composition range of 0.50–2.00 mol % SrO was studied and compared to pure TiO{sub 2}. Experimental evidence shows that small amounts of SrO improve the nonlinear properties of the samples significantly. Optimal varistor characteristics α = 5.50 and E{sub b} = 345 V/cm, were obtained with 1.00 mol % SrO-doped TiO{sub 2}. SrO in larger amounts causes the formation of precipitates of the SrTiO{sub 3} layer on the microstructure, being deleterious to the electrical properties. Therefore, dopants such as SrO or TiO{sub 2} play a special role in the morphology of the grain boundary and nonlinear response of these materials. An atomic defect model based on the double barrier Schottky type can be adopted to explain the formation of electrical barriers in TiO{sub 2} grain boundaries. - Highlights: • Training an effective potential barrier in the grain boundary, measured by electrical measurements on AC and DC. • Microstructure versus electrical properties. • Good properties getting varistor using a single dopant, forming a varistor binary system based on TiO{sub 2}.

Intrinsic Conductivity in Magnesium-Oxygen Battery Discharge Products: MgO and MgO2

DEFF Research Database (Denmark)

Smith, Jeffrey G.; Naruse, Junichi; Hiramatsu, Hidehiko

2017-01-01

Nonaqueous magnesium–oxygen (or “Mg-air”) batteries are attractive next generation energy storage devices due to their high theoretical energy densities, projected low cost, and potential for rechargeability. Prior experiments identified magnesium oxide, MgO, and magnesium peroxide, MgO2...

40 CFR 98.86 - Data reporting requirements.

Science.gov (United States)

2010-07-01

... tons CO2/metric ton CKD produced). (12) Annual organic carbon content of each raw material (wt-fraction... (number of quarters) (vi) Organic carbon contents of raw materials (number of times). (vii) Raw material...) Monthly fraction of total CaO, total MgO, non-calcined CaO and non-calcined MgO in clinker for each kiln...

Glass-ceramic joint and method of joining

Science.gov (United States)

Meinhardt, Kerry D [Richland, WA; Vienna, John D [West Richland, WA; Armstrong, Timothy R [Clinton, TN; Pederson, Larry R [Kennewick, WA

2003-03-18

The present invention is a glass-ceramic material and method of making useful for joining a solid ceramic component and at least one other solid component. The material is a blend of M1-M2-M3, wherein M1 is BaO, SrO, CaO, MgO, or combinations thereof, M2 is Al.sub.2 O.sub.3, present in the blend in an amount from 2 to 15 mol %, M3 is SiO.sub.2 with up to 50 mol % B.sub.2 O.sub.3 that substantially matches a coefficient of thermal expansion of the solid electrolyte. According to the present invention, a series of glass ceramics in the M1-Al.sub.2 O.sub.3 -M3 system can be used to join or seal both tubular and planar solid oxide fuel cells, oxygen electrolyzers, and membrane reactors for the production of syngas, commodity chemicals and other products.

The influence of Al2O3, MgO and ZnO on the crystallization characteristics and properties of lithium calcium silicate glasses and glass-ceramics

International Nuclear Information System (INIS)

Salman, S.M.; Darwish, H.; Mahdy, E.A.

2008-01-01

The crystallization characteristics of glasses based on the Li 2 O-CaO-SiO 2 eutectic (954 ± 4 deg. C) system containing Al 2 O 3 , MgO and ZnO has been investigated by differential thermal analysis (DTA), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The partial replacement of Li 2 O by Al 2 O 3 and CaO by MgO or ZnO in the studied glass-ceramics led to the development of different crystalline phase assemblages, including lithium meta- and di-silicates, lithium calcium silicates, α-quartz, diopside, clinoenstatite, wollastonite, β-eucryptite ss, β-spodumene, α-tridymite, lithium zinc orthosilicate, hardystonite and willemite using various heat-treatment processes. The dilatometric thermal expansion of the glasses and their corresponding glass-ceramics were determined. A wide range of thermal expansion coefficient values were obtained for the investigated glasses and their corresponding crystalline products. The thermal expansion coefficients of the investigated glasses were decreased by Al 2 O 3 , MgO or ZnO additions. The α-values of the investigated glasses were ranged from (+18) to (+108) x 10 -7 K -1 (25-300 deg. C), while those of the glass-ceramics were (+3) to (+135) x 10 -7 K -1 (25-700 deg. C). The chemical durability of the glass-ceramics, towards the attack of 0.1N HCl solution, was markedly improved by Al 2 O 3 with MgO replacements. The composition containing 11.5 mol% Al 2 O 3 and 6.00 mol% MgO exhibited low thermal expansion values and good chemical durability

Structural and physico-chemical analysis of calcium/strontium substituted, near-invert phosphate based glasses for biomedical applications.

Science.gov (United States)

Patel, U; Moss, R M; Hossain, K M Z; Kennedy, A R; Barney, E R; Ahmed, I; Hannon, A C

2017-09-15

Neutron diffraction, 23 Na and 31 P NMR, and FTIR spectroscopy have been used to investigate the structural effects of substituting CaO with SrO in a 40P 2 O 5 ·(16-x)CaO·20Na 2 O·24MgO·xSrO glass, where x is 0, 4, 8, 12 and 16mol%. The 31 P solid-state NMR results showed similar amounts of Q 1 and Q 2 units for all of the multicomponent glasses investigated, showing that the substitution of Sr for Ca has no effect on the phosphate network. The M-O coordinations (M=Mg, Ca, Sr, Na) were determined for binary alkali and alkaline earth metaphosphates using neutron diffraction and broad asymmetric distributions of bond length were observed, with coordination numbers that were smaller and bond lengths that were shorter than in corresponding crystals. The Mg-O coordination number was determined most reliably as 5.0(2). The neutron diffraction results for the multicomponent glasses are consistent with a structural model in which the coordination of Ca, Sr and Na is the same as in the binary metaphosphate glass, whereas there is a definite shift of Mg-O bonds to longer distance. There is also a small but consistent increase in the Mg-O coordination number and the width of the distribution of Mg-O bond lengths, as Sr substitutes for Ca. Functional properties, including glass transition temperatures, thermal processing windows, dissolution rates and ion release profiles were also investigated. Dissolution studies showed a decrease in dissolution rate with initial addition of 4mol% SrO, but further addition of SrO showed little change. The ion release profiles followed a similar trend to the observed dissolution rates. The limited changes in structure and dissolution rates observed for substitution of Ca with Sr in these fixed 40mol% P 2 O 5 glasses were attributed to their similarities in terms of ionic size and charge. Phosphate based glasses are extremely well suited for the delivery of therapeutic ions in biomedical applications, and in particular strontium plays an

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

KAUST Repository

Diaz-Sanchez, V.; F. Estrada, A.; Limon, M. C.; Al-Babili, Salim; Avalos, J.

2013-01-01

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.

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.

Improvement in fatigue property for a PZT ferroelectric film device with SRO electrode film prepared by chemical solution deposition

International Nuclear Information System (INIS)

Miyazaki, H.; Miwa, Y.; Suzuki, H.

2007-01-01

PZT films with (1 0 0) and (1 1 0) orientation were prepared by spin coating using the chemical solution deposition (CSD) method on an SRO/Si or a Pt/Ti/SiO 2 /Si substrate. The remnant polarization and the saturation polarization of the PZT/SRO/Si film were 21 and 35 μC/cm 2 , and those of the PZT/Pt/Ti/SiO 2 /Si film were 20 and 31 μC/cm 2 . The remnant polarization of the PZT/SRO/Si film maintained more than 10 8 switching cycles, and the fatigue property was observed for the PZT film fabricated on the Pt/Ti/SiO 2 /Si electrode

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.

Marketingová strategie firmy Helder s.r.o.

OpenAIRE

Šlemrová, Lucie

2014-01-01

The aim of the master's thesis is to analyze present marketing strategy of company Helder and to suggest specific alteration of company's marketing strategy and also recommend direction which should company tend to in future. Theoretical part of thesis will be focused on basic concepts and techniques related to the aim of this work. In practical part of thesis will be introduced company Helder s.r.o. and its marketing strategy. Practical benefit from this work will be realization of analysis ...

Numerical solutions of anharmonic vibration of BaO and SrO molecules

Energy Technology Data Exchange (ETDEWEB)

Pramudito, Sidikrubadi; Sanjaya, Nugraha Wanda [Theoretical Physics Division, Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia); Sumaryada, Tony, E-mail: tsumaryada@ipb.ac.id [Theoretical Physics Division, Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia); Computational Biophysics and Molecular Modeling Research Group (CBMoRG), Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia)

2016-03-11

The Morse potential is a potential model that is used to describe the anharmonic behavior of molecular vibration between atoms. The BaO and SrO molecules, which are two almost similar diatomic molecules, were investigated in this research. Some of their properties like the value of the dissociation energy, the energy eigenvalues of each energy level, and the profile of the wavefunctions in their correspondence vibrational states were presented in this paper. Calculation of the energy eigenvalues and plotting the wave function’s profiles were performed using Numerov method combined with the shooting method. In general we concluded that the Morse potential solved with numerical methods could accurately produce the vibrational properties and the wavefunction behavior of BaO and SrO molecules from the ground state to the higher states close to the dissociation level.

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).

Theoretical Limiting Potentials in Mg/O2 Batteries

DEFF Research Database (Denmark)

Smith, Jeffrey G.; Naruse, Junichi; Hiramatsu, Hidehiko

2016-01-01

A rechargeable battery based on a multivalent Mg/O2 couple is an attractive chemistry due to its high theoretical energy density and potential for low cost. Nevertheless, metal-air batteries based on alkaline earth anodes have received limited attention and generally exhibit modest performance....... In addition, many fundamental aspects of this system remain poorly understood, such as the reaction mechanisms associated with discharge and charging. The present study aims to close this knowledge gap and thereby accelerate the development of Mg/O2 batteries by employing first-principles calculations...... by the presence of large thermodynamic overvoltages. In contrast, MgO2-based cells are predicted to be much more efficient: superoxide-terminated facets on MgO2 crystallites enable low overvoltages and round-trip efficiencies approaching 90%. These data suggest that the performance of Mg/O2 batteries can...

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...

Positronium hydride defects in thermochemically reduced alkaline-Earth oxides

International Nuclear Information System (INIS)

Monge, M.A.; Pareja, R.; Gonzalez, R.; Chen, Y.

1997-01-01

Thermochemical reduction of both hydrogen-doped MgO and CaO single crystals results in large concentrations of hydride (H - ) ions. In MgO crystals, positron lifetime and Doppler broadening experiments show that positrons are trapped at H - centers forming positronium hydride molecules [e + - H - ]. A value of 640 ps is obtained for the lifetime of the PsH states located in an anion vacancy In MgO positrons are also trapped at H 2- sites at low temperatures. The H 2- ions were induced in the crystals by blue light illumination. The formation of PsH states in CaO could not be conclusively established. (orig.)

Návrh strategie vstupu na slovenský trh pro společnost ADCALL systems s.r.o.

OpenAIRE

Lidmila, Ondřej

2015-01-01

The main topic of thesis is draft strategy of entrance on Slovak market for company ADCALL systems s.r.o. Thesis has two parts - Literary review and Results. In Literary review is summarized issues relating to the topic of thesis and it is made in the basis of study of scientific publications. Second part - Results is based on internal analysis of company ADCALL systems s.r.o. and external analysis of Slo-vak market. On the ground of this two analysis is decided, that this business can expand...

CHEMISTRY OF SO2 AND DESOX PROCESSES ON OXIDE NANOPARTICLES.

Energy Technology Data Exchange (ETDEWEB)

RODRIGUEZ, J.A.

2006-06-30

On bulk stoichiometric oxides, SO{sub 2} mainly reacts with the O centers to form SO{sub 3} or SO{sub 4} species that decompose at elevated temperatures. Adsorption on the metal cations occurs below 300 K and does not lead to cleavage of the S-O bonds. In bulk oxides, the occupied cation bands are too stable for effective bonding interactions with the LUMO of SO{sub 2}. The effects of quantum confinement on the electronic properties of oxide nanoparticles and the structural defects that usually accompany these systems in general favor the bonding and dissociation of SO{sub 2}. Thus, nanoparticles of MgO, CaO, SrO, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3} and CeO{sub 2} are all more efficient for sequestering SO{sub 2} than the corresponding bulk oxides. Structural imperfections in pure or metal-doped ceria nanoparticles accelerate the reduction of SO{sub 2} by CO by facilitating the formation and migration of O vacancies in the oxide surface.

Strong excitonic interactions in the oxygen K-edge of perovskite oxides

Energy Technology Data Exchange (ETDEWEB)

Tomita, Kota; Miyata, Tomohiro [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Olovsson, Weine [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Mizoguchi, Teruyasu, E-mail: teru@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)

2017-07-15

Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO{sub 3}, SrTiO{sub 3}, and BaTiO{sub 3}, together with reference oxides, MgO, CaO, SrO, BaO, and TiO{sub 2}, were investigated using a first-principles Bethe–Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti–O–Ti bonds. - Highlights: • Excitonic interaction in oxygen-K edge is investigated. • Strong excitonic interaction is found in the oxygen-K edge of perovskite oxides. • The strong excitonic interaction is ascribed to the low-dimensional and confined electronic structure.

Graffiti mochicas en la huaca Cao Viejo, Complejo El Brujo

Directory of Open Access Journals (Sweden)

2001-01-01

Full Text Available GRAFFITI MOCHICA DE LA HUACA CAO VIEJO, COMPLEXE ARCHÉOLOGIQUE DU BRUJO. Sur des murs et colonnes de quatre des sept édifices superposés (E, D, B, A qui forment la huaca Cao Viejo, nous avons identifié des graffitis qui représentent une grande variété de dessins. Nous analysons actuellement leur élaboration, les techniques employées, leur mise en relation, leur chronologie relative, et leur présence dans d’autres sites monumentaux de la côte péruvienne. En las superficies de muros y columnas de cuatro de los siete edificios superpuestos (E, D, B, A que forman la Huaca Cao Viejo, se han identificado graffiti en una amplia variedad de diseños. Se discute el propósito de su elaboración, la técnica, asociaciones, cronología relativa, y su recurrencia en otros sitios monumentales de la costa peruana. MOCHICA GRAFFITI IN HUACA CAO VIEJO, EL BRUJO COMPLEX. On the surfaces and columns of four among seven superimposed phases (E,D,B,A that form the Huaca Cao Viejo, graffiti representing a great variety of designs were discovered. We discuss their relevance, their significance, the techniques used in creating them, their relative chronology, and their use in other monumental buildings on the northern Peruvian coast.

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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rearrangement of porous CaO aggregates during calcite decomposition in vacuum

International Nuclear Information System (INIS)

Beruto, D.; Barco, L.; Searcy, A.W.

1983-01-01

High-resolution SEM photographs, N 2 adsorption isotherms, Hg porosimetry, and micrometer measurements were used to characterize CaO particle shapes and pore-size distributions that result when calcite crystals are decomposed in vacuum at 686 0 C. The surface area of the CaO produced from large calcite crystals is constant at 116 + or - 4 m 2 /g independent of the extent of reaction. The volume occupied by a CaO aggregate is approx. = 98 + or - 2% that of the original calcite crystal. The approx. = 54% total porosity is comprised of 42% pores of approx. = 5 nm cross section and 12% pores of approx. = 10 μm cross section. The duplex pore structure is formed by a diffusionless repacking of CaO particles that initially form with a more uniform distribution of particles and pores

Nonisothermal Thermogravimetric Analysis of Thai Lignite with High CaO Content

Science.gov (United States)

Pintana, Pakamon

2013-01-01

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. PMID:24250259

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 SO 2 content in calciner gas were comprehensively analyzed; and an advantageous recycling condition of MgO and SO 2 from by-products was summarized. Results showed that the SO 2 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 SO 2 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 SO 2 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.

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...

Combined Use of Shrinkage Reducing Admixture and CaO in Cement Based Materials

Science.gov (United States)

Tittarelli, Francesca; Giosuè, Chiara; Monosi, Saveria

2017-10-01

The combined addition of a Shrinkage-Reducing Admixture (SRA) with a CaO-based expansive agent (CaO) has been found to have a synergistic effect to improve the dimensional stability of cement based materials. In this work, aimed to further investigate the effect, mortar and self-compacting concrete specimens were prepared either without admixtures, as reference, or with SRA alone and/or CaO. Their performance was compared in terms of compressive strength and free shrinkage measurements. Results showed that the synergistic effect in reducing shrinkage is confirmed in the specimens manufactured with SRA and CaO. In order to clarify this phenomenon, the effect of SRA on the hydration of CaO as well as cement was evaluated through different techniques. The obtained results show that SRA induces a finer microstructure of the CaO hydration products and a retarding effect on the microstructure development of cement based materials. A more deformable mortar or concrete, due to the delay in microstructure development by SRA, coupled with a finer microstructure of CaO hydration products could allow higher early expansion, which might contribute in contrasting better the successive drying shrinkage.

Dessicant materials screening for backfill in a salt repository

International Nuclear Information System (INIS)

Simpson, D.R.

1980-10-01

Maintaining an anhydrous environment around nuclear waste stored in a salt repository is a concern which can be alleviated by using a desiccant material for backfilling. Such a desiccant should desiccate a brine yet be non deliquescent, the hydrated product should have moderate thermal stability, and the desiccant should have a high capacity and be readily available. From a literature search MgO and CaO were identified for detailed study. These oxides, and an intimate mixture of the two obtained by calcining dolomite, were used in experiments to further determine their suitability. They proved to be excellent desiccants with a high water capacity. The hydrates of both have moderate thermal stability and a high water content. Both MgO and CaO react in an alkaline chloride brine forming oxychloride compounds with different waters of crystallization. Some of these compounds are the Sorel Cements. CaO hydrates to Ca(OH) 2 which carbonates with CO 2 in air to form CaCO 3 and release the hydrated water. Thus the intimate mixture of CaO and MgO from calcined dolomite may serve as a desiccant and remove CO 2 from the repository atmosphere

Dessicant materials screening for backfill in a salt repository

Energy Technology Data Exchange (ETDEWEB)

Simpson, D.R.

1980-10-01

Maintaining an anhydrous environment around nuclear waste stored in a salt repository is a concern which can be alleviated by using a desiccant material for backfilling. Such a desiccant should desiccate a brine yet be non deliquescent, the hydrated product should have moderate thermal stability, and the desiccant should have a high capacity and be readily available. From a literature search MgO and CaO were identified for detailed study. These oxides, and an intimate mixture of the two obtained by calcining dolomite, were used in experiments to further determine their suitability. They proved to be excellent desiccants with a high water capacity. The hydrates of both have moderate thermal stability and a high water content. Both MgO and CaO react in an alkaline chloride brine forming oxychloride compounds with different waters of crystallization. Some of these compounds are the Sorel Cements. CaO hydrates to Ca(OH)/sub 2/ which carbonates with CO/sub 2/ in air to form CaCO/sub 3/ and release the hydrated water. Thus the intimate mixture of CaO and MgO from calcined dolomite may serve as a desiccant and remove CO/sub 2/ from the repository atmosphere.

Estudo de materiais calcários usados como corretivos do solo no Estado de São Paulo. II - Composição química Chemical composition of limestones employed in neutralizing soil acidity in the State of São Paulo

Directory of Open Access Journals (Sweden)

Bernardo van Raij

1968-01-01

Full Text Available Foram feitas determinações de óxido de cálcio (CaO, óxido de magnésio (MgO, sesquióxidos (R203, perda ao fogo (P.F., resíduo insolúvel (R.I., umidade (H20, poder de neutralização (P.N. de 16 calcários sedimentares, 11 calcários metamórficos, 1 calcário magmático e 2 escórias de siderurgia, materias utilzados como corretivos do solo no Estado de São Paulo.The contents of CaO, MgO, R2O3, loss of ignition, insoluble residue and the neutralization value of 29 limestones and 2 siderurgy slags employed in the neutralization of soil acidity in the State of São Paulo were determined. The results showed that most of the limestones studied belonged to the dolomitic type. The neutralization value was higher in the samples containing higher percentage of CaO plus MgO.

Optimalizace manipulační techniky v podniku Nestlé Česko s.r.o., závod ZORA Olomouc

OpenAIRE

Kovář, Jiří

2015-01-01

This thesis discusses the optimal way of material-handling equipment replacement at Nestlé Česko s.r.o., plant ZORA Olomouc. The theoretical part describes the issue of warehousing in general and focuses on the material-handling equipment and vehicles. The following analytical part focuses specifically on the company Nestlé Česko s.r.o., particularly the plant ZORA Olomouc with the foremost aim of analysing and optimising the current material-handling equipment.

Marketingový plán firmy Eurocat, s.r.o. pro zavedení produktu Gelmodel Premioum na sportovní trh

OpenAIRE

Knotková, Kristýna

2009-01-01

The marketing plan of a company Eurocat, s.r.o. for implementation of product Gelmodel Premium to sports market Abstarct: The thesis is focused on marketing plan for implementation of product Gelmodel Premium to sports market. Theoretical part defines basic terms - marketing or marketing plan and describes a process of completing a marketing plan theoretically.The practical part presents company Eurocat, s.r.o. and describes product Gelmodel Premium. And then situational analyse is achieved. ...

WIPP Magnesium Oxide (MgO) - Planned Change Request

Science.gov (United States)

On April 10, 2006, the DOE submitted a planned change request pertaining to the amount of MgO emplaced in the WIPP repository. MgO is an engineered barrier that DOE included as part of the original WIPP Certification Decision.

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. Copyright © 2013 Elsevier B.V. All rights reserved.

Sulfation of CaO particles in a carbonation/calcination loop to capture CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Grasa, G.S.; Alonso, M.; Abanades, J.C. [CSIC, Zaragoza (Spain)

2008-03-15

CaO is being proposed as a regenerable sorbent of CO{sub 2} via a carbonation/calcination loop. It is well known that natural sorbents lose their capacity to capture CO{sub 2} with the number of cycles due to textural degradation. In coal combustion systems, reaction with the SO{sub 2} present in flue gases also causes sorbent deactivation. This work investigates the effect of partial sorbent sulfation on the amount of CaO used in systems where both carbonation and sulfation reactions are competing. We have found that SO{sub 2} reacts with the deactivated CaO resulting from repetitive calcination/carbonation reactions. Therefore, the deactivation of CaO as a result of the presence of SO{sub 2} is lower than one would expect if one assumes that SO{sub 2} reacts only with active CaO. This work shows that changes in the texture of the sorbent due to repetitive carbonation/calcination cycles tend to increase the sulfation capacity of the sorbents tested. This suggests that the purge of deactivated CaO obtained from a CO{sub 2} capture loop could be a more effective sorbent of SO{sub 2} than fresh CaO.

Odhad hodnoty spoločnosti Automotive lighting, s.r.o

OpenAIRE

Bogyová, Zuzana

2011-01-01

Diploma thesis deals with the valuation of the automotive company Automotive lighting, s.r.o for the management needs. The estimated value refers to October 2012. The basis for the valuation is strategic and financial analysis. The results will be taken into account for establishment of the financial plan, which will be used in the valuation process. Emphasis is placed on yield methods using free cash flow to the firm(FCFF) and economic value added EVA. Both methods are compared with book val...

Study on rapid bio-drying technology of cow dung with CaO2

Science.gov (United States)

Chen, Xiaotian; Qu, Guangfei; Liu, Shugen; Xie, Ruosong; He, Yanhua

2017-05-01

Effect of CaO2 on cow dung rapid bio-drying technology was researched. A static aerobic composting system was applied to this experiment which combining natural ventilation with Turing in the process of composting. The physical characteristics of cow dung was observed and the compost temperature, moisture content, organic matter, total nitrogen, total phosphorus, potassium content was determined which in order to study the effect of CaO2 on rapid drying of cattle in the compost. In the initial stage of compost, adding CaO2 groups compared with the control group, the temperature rise faster, 4-6 days in advance to the thermophilic phase; at the end of composting, the CaO2 composition and moisture content decreased significantly to below 30%. The addition of CaO2 in fertilizer was shorten the composting time, extend the thermophilic phase, to provide sufficient oxygen meeting the growth needs of aerobic microorganisms. It convinced that the rapid bio-drying of dairy manure has a good effect and provided a new idea for the effective treatment of cow dung.

Use of porous MgO in pyrochemical applications

International Nuclear Information System (INIS)

Maiya, P.S.; Sweeney, S.M.; Carroll, L.A.; Dusek, J.T.

1994-11-01

Pyrochemical methods for the extraction of transuranic elements from light water reactor spent fuel require a reduction step in which the oxide fuel is reduced to metals by Li in molten LiCl. The Li 2 O formed is electrolytically reduced to metal in a cell that uses a carbon (or inert) anode and a Li cathode to recycle the salt and minimize the waste. Use of a carbon anode causes carbon dust that interferes with the process. Moreover, current efficiency is reduced as a result of oxidation of Li to Li 2 O by CO 2 . A porous MgO shroud around the anode was found to obviate these problems. Porous MgO crucibles and rectangular bar specimens were fabricated from MgO powders (electrically fused MgO, reagent grade MgO were mixed in appropriate combinations with a binder and lubricant). Particle size, force applied to the powders during cold pressing, and sintering temperature were varied to achieve a total porosity of >45% (mostly open porosity) and to control pore size and pore distribution. Mercury intrusion porosimetry was used to determine the pore size and pore size distribution. Flexural strength is observed to be proportional to the square root of pore size, which is consistent with fracture mechanics

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)

MgO nanoparticles as antibacterial agent: preparation and activity

International Nuclear Information System (INIS)

Tang, Zhen-Xing; Lv, Bin-Feng

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 reviewed. (author)

Synthesis and Characterization of Some Alkaline-Earth-Oxide Nanoparticles

Science.gov (United States)

Singh, Jitendra Pal; Lim, Weon Cheol; Won, Sung Ok; Song, Jonghan; Chae, Keun Hwa

2018-04-01

The present work reports the synthesis of MgO and CaO nanoparticles by using the sol-gel autocombustion method. The annealing of the precursor at 1200 °C was observed to lead the formation of MgO nanoparticles having average crystallite size of 31 nm. Annealing the precursor at same temperature produced materials having a CaO phase with a minor impure phase of calcium carbonate ( 3%). The crystallite size corresponding to the CaO phase was 38 nm. A change of thermal history in the precursor was observed not to result in an improvement of the CaO phase. The change of thermal history in the precursor gave rise to mixed phases of CaCO3 and Ca(OH)2 rather than the phase of CaO. Further, annealing at 1200 °C for 12 h resulted in the formation of the CaO phase along with almost 1 - 5% of calcium hydroxide as an impurity phase. X-ray absorption spectroscopic measurements carried out on these materials revealed that the local electronic/atomic structure of these oxides was not only affected by the impurity phases but also influenced by the carbaneous impurities attached to the crystallites.

Ocenenie podniku IKEA Česká republika, s.r.o.

OpenAIRE

Pituchová, Vladimíra

2012-01-01

The focal point of the thesis is the valuation of IKEA Česká republika, s.r.o. estimated as of December 31, 2012. Resulting value is set both on equity and enterpise levels. Financial analysis of the company, analyses of the macroeconomic and microeconomic environment and firm's position on a given market are included in the valuation process. To determine the value of company yield methods are applied: discounted free cash flow to firm (FCFF), discounted free cash flow to equity (FCFE) and d...

Stanovaní hodnoty podniku GlaxoSmithKline s.r.o.

OpenAIRE

Mádle, Jakub

2014-01-01

As a goal of my thesis a have desided to evaluate company GlaxoSmithKline sro. Firstly, I conducted a strategic analysis in which I focused on the macro and micro environment. Then I continued with a financial analysis of the company, during which I apllied the horizontal, vertical and ratio analysis. That showed that company management is fine and it is possible to determine the value of the company. To confirm this fact, I applied bankruptcy and credibility models. Then I continued with the...

Synthesis of Doped and non-Doped Nano MgO Ceramic Membranes

Directory of Open Access Journals (Sweden)

Shiraz Labib

2013-12-01

Full Text Available Doped and non-doped MgO coated thin films on alumina substrates were prepared using a chelating sol-gel method under controlled conditions to prepare nanomaterials with unprecedented properties. The effect of doping of ZnO on thermal, surface and structural properties was investigated using DTA-TG, BET and XRD respectively. Also microstructural studies and coating thickness measurements of MgO thin film were conducted using SEM. An increase in the thermal stability of MgO with increasing ZnO doping percent was observed. The increase of ZnO doping percent showed a marked decrease in the average particle size of MgO powder as a result of the replacement of some Mg2+ by Zn2+ which has similar ionic radius as Mg2+. This decrease in particle size of MgO was also related to the decrease of the degree of MgO crystalinity. The increase of ZnO doping also showed a marked decrease in coating thickness values of the prepared membranes. This decrease was related to the  mechanism of ZnO doping into a MgO crystal lattice.

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.

Evaporation mechanisms of MgO in laser assisted atom probe tomography

KAUST Repository

Mazumder, Baishakhi; Vella, Angela; Dé conihout, Bernard; Al-Kassab, Talaat

2011-01-01

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.

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.

Nanosilica supported CaO: A regenerable and mechanically hard CO2 sorbent at Ca-looping conditions

International Nuclear Information System (INIS)

Sanchez-Jimenez, P.E.; Perez-Maqueda, L.A.; Valverde, J.M.

2014-01-01

Highlights: • A synthetic CO 2 sorbent is prepared by impregnation of calcium nitrate on a nanosilica matrix. • Sintering of the nascent CaO in the calcination stage of carbonation/calcination cycles is hindered. • CaO conversion reaches a stable value well above the residual conversion of natural limestone. • Particle fragmentation as caused by ultrasonic irradiation in a liquid dispersion is hindered. - Abstract: This work presents a CO 2 sorbent that may be synthesized from low-cost and widely available materials following a simple method basically consisting of impregnation of a nanostructured silica support with a saturated solution of calcium nitrate. In a first impregnation stage, the use of a stoichiometric CaO/SiO 2 ratio serves to produce a calcium silicate matrix after calcination. This calcium silicate matrix acts as a thermally stable and mechanically hard support for CaO deposited on it by further impregnation. The CaO-impregnated sorbent exhibits a stable CaO conversion at Ca-looping conditions whose value depends on the CaO wt% deposited on the calcium silicate matrix, which can be increased by successive reimpregnations. A 10 wt% CaO impregnated sorbent reaches a stable conversion above 0.6 whereas the stable conversion of a 30 wt% CaO impregnated sorbent is around 0.3, which is much larger than the residual conversion of CaO derived from natural limestone (between 0.07 and 0.08). Moreover, particle size distribution measurements of samples predispersed in a liquid and subjected to high energy ultrasonic waves indicate that the CaO-impregnated sorbent has a relatively high mechanical strength as compared to limestone derived CaO

Marketingová strategie společnosti Camp Leaders s.r.o.

OpenAIRE

Švubová, Tereza

2014-01-01

The bachelor thesis deals with the marketing strategy of the company Camp Leaders s.r.o. in the Czech Republic. The main objective of the work is to analyse the marketing strategy. The first chapter explains some key concepts of marketing. The second chapter is dedicated to the introduction of the company Camp Leaders, part of the Smaller Earth. Then the second chapter analyses the marketing mix of this company and the main competitors of providing Work&Travel programmes are introduced. The m...

MgO monolayer epitaxy on Ni (100)

Science.gov (United States)

Sarpi, B.; Putero, M.; Hemeryck, A.; Vizzini, S.

2017-11-01

The growth of two-dimensional oxide films with accurate control of their structural and electronic properties is considered challenging for engineering nanotechnological applications. We address here the particular case of MgO ultrathin films grown on Ni (100), a system for which neither crystallization nor extended surface ordering has been established previously in the monolayer range. Using Scanning Tunneling Microscopy and Auger Electron Spectroscopy, we report on experiments showing MgO monolayer (ML) epitaxy on a ferromagnetic nickel surface, down to the limit of atomic thickness. Alternate steps of Mg ML deposition, O2 gas exposure, and ultrahigh vacuum thermal treatment enable the production of a textured film of ordered MgO nano-domains. This study could open interesting prospects for controlled epitaxy of ultrathin oxide films with a high magneto-resistance ratio on ferromagnetic substrates, enabling improvement in high-efficiency spintronics and magnetic tunnel junction devices.

Soluble salts addition modifies MgO hydration

International Nuclear Information System (INIS)

Santos, A.M.; Pandolfelli, V.C.; Salomao, R.

2012-01-01

Magnesium oxide (MgO) show great technological interest on refractories due to its high refractoriness, basic slag corrosion resistance and competitive cost. However, the hydration reaction of MgO produces magnesium hydroxide. This reaction generates a significant volumetric expansion that can lead to material breakdown inhibiting its use in refractory castables. This reaction can be affected by several factors such as magnesia source, purity, calcination temperature, pH, CaO/SiO 2 ratio and agitation speed. In the present work, soluble salts (CaCl 2 and MgCl 2 ) were used in MgO aqueous suspensions (caustic and sinter). The results were evaluated by means of techniques of degree of hydration (termogravimetric), Scanning electron microscopy, apparent volumetric expansion and x-ray Diffraction which showed that the degree of hydration was noticeably less to sinter aqueous and the expansive effects were less with the addition of CaCl 2 . (author)

Mangotoxin production of Pseudomonas syringae pv. syringae is regulated by MgoA.

Science.gov (United States)

Carrión, Víctor J; van der Voort, Menno; Arrebola, Eva; Gutiérrez-Barranquero, José A; de Vicente, Antonio; Raaijmakers, Jos M; Cazorla, Francisco M

2014-02-21

The antimetabolite mangotoxin is a key factor in virulence of Pseudomonas syringae pv. syringae strains which cause apical necrosis of mango trees. Previous studies showed that mangotoxin biosynthesis is governed by the mbo operon. Random mutagenesis led to the identification of two other gene clusters that affect mangotoxin biosynthesis. These are the gacS/gacA genes and mgo operon which harbors the four genes mgoBCAD. The current study shows that disruption of the nonribosomal peptide synthetase (NRPS) gene mgoA resulted in loss of mangotoxin production and reduced virulence on tomato leaves. Transcriptional analyses by qPCR and promoter reporter fusions revealed that mbo expression is regulated by both gacS/gacA and mgo genes. Also, expression of the mgo operon was shown to be regulated by gacS/gacA. Heterologous expression under the native promoter of the mbo operon resulted in mangotoxin production in non-producing P. syringae strains, but not in other Pseudomonas species. Also introduction of the mbo and mgo operons in nonproducing P. protegens Pf-5 did not confer mangotoxin production but did enhance transcription of the mbo promoter. From the data obtained in this study, we conclude that both mbo and mgo operons are under the control of the gacS/gacA two-component system and that the MgoA product acts as a positive regulator of mangotoxin biosynthesis.

Yield estimation for nuclear explosions of semipalatinsk using rayleigh waves recorded at SRO, Mashhad

International Nuclear Information System (INIS)

Naghizadeh, M.; Javaherian, A.; Sadidkhooy, A.

2005-01-01

Surface wave amplitudes from explosion sources show less variation for a given event than body wave amplitudes, so it is natural to expect that yield estimation derived from surface waves will be more accurate than yield estimation derived from body waves. However yield estimation from surface waves is complicated by the presence of tectonic strain release, which acts like one or more earthquake sources superimposed on the explosion. Explosions on an island or near a mountain slope can exhibit anomalous surface waves similar to those caused by tectonic strain release. One of the methods in estimating the yield of nuclear explosions is to determine a relationship between the magnitude and the yield of an explosion. The kind of magnitude employed has an important role in this regard. In this paper, vertical component of long period seismograms at SRO, Mashhad from explosions occurred in semipalatinsk test site, semipalatinsk test site east of Kazakhstan) are considered. First, by using the relationships of IASPEI and Rezapour and Pearce (1998), we determined surface wave magnitude (MS) which is defined as the logarithm of the amplitude plus a distance correction. Then we derived a relation for M S versus yield for a data set which includes a 15 long period seismograms recorded at SRO Mashhad station from semipalatinsk test site nuclear explosions. Furthermore, by digitizing the vertical component of seismograms and transforming them to the frequency domain, the mean amplitude of records at frequency ranges of 0.04-0.06 Hz were calculated. Then, surface wave magnitudes in the frequency domain (M Sf ) and their corresponding yield-magnitude relationship were obtained. By comparing correlation coefficients of these two yield-magnitude relationships, following relationship M S = 1.079 log(Y) + 1.714, was chosen for estimating the yield of semipalatinsk test site nuclear explosion from seismograms of SRO

[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.

Marketingová strategie společnosti Bambule Alltoys, spol. s.r.o.

OpenAIRE

Kopová, Petra

2011-01-01

Topic of this thesis is marketing strategy analysis and assessment of toy retail chain Bambule Alltoys, spol. s.r.o. In addition, this paper deals with recommendations, which could strengthen company's position on the market and help it in meeting its strategic objectives. The theoretical part addresses the definition of strategic marketing and characterizes the strategic marketing management process. It also describes the specifics of consumer goods marketing and current trends in the Europe...

Preparation of nanocrystalline MgO by surfactant assisted precipitation method

International Nuclear Information System (INIS)

Rezaei, Mehran; Khajenoori, Majid; Nematollahi, Behzad

2011-01-01

Highlights: → Nanocrystalline magnesium oxide with high surface area. → MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. → MgO prepared with surfactant showed a plate-like shape. → 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 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) 2 crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH) 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 increased the specific surface area

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

Aplicaciones del Caos y la Complejidad en la Cadena de Suministros del Sector Agroindustrial

OpenAIRE

Lara Atencia, Manuel Santiago

2016-01-01

La presente investigación consiste en determinar las aplicaciones existentes de las teorías del caos y las teorías de la complejidad en la cadena de suministro del sector agroindustrial colombiano. Además, tiene como propósito describir el sector de la agroindustria y la cadena de suministro, identificar los modelos de caos y complejidad y posteriormente determinar cuáles de éstos son aplicables al sector. Se define el caos como una sub-disciplina de las matemáticas que estudia sistemas compl...

MgO encapsulated mesoporous zeolite for the side chain alkylation of toluene with methanol.

Science.gov (United States)

Jiang, Nanzhe; Jin, Hailian; Jeong, Eun-Young; Park, Sang-Eon

2010-01-01

Side chain alkylation of toluene with methanol was studied over mesoporous zeolite supported MgO catalysts. MgO were supported onto the carbon templated mesoporous silicalite-1 by direct synthesis route under microwave conditions. This direct synthesis route yields the majority of MgO highly dispersed into the mesopores of the silicalite-1 crystals. The vapor phase alkylation of toluene with methanol was performed over these catalysts under vapor phase conditions at atmospheric pressure. Mesoporous silicalite-1 supported MgO catalysts gave improved yields towards side chain alkylated products compared to the bulk MgO. The higher activity exhibited by 5% MgO supported on mesoporous silicalite compared to the one with 1% MgO can be attributed to the large number of weak basic sites observed from the CO2 TPD.

Defect Study of MgO-CaO Material Doped with CeO2

Directory of Open Access Journals (Sweden)

Han Zhang

2013-01-01

Full Text Available MgO-CaO refractories were prepared using analytical reagent chemicals of Ca(OH2 and Mg(OH2 as starting materials and CeO2 as dopant, then sintered at 1650°C for 3 h. The effect of CeO2 powders on the defect of MgO-CaO refractories was investigated. The sample characterizations were analyzed by the techniques of XRD and SEM. According to the results, with the addition of CeO2, the lattice constant of CaO increased, and the bulk density of the samples increased while apparent porosity decreased. The densification of MgO-CaO refractories was promoted obviously. In the sintering process, MgO grains grew faster than CaO, pores at the MgO-CaO grain boundaries decreased while pores in the MgO grains increased gradually, and no pores were observed in the CaO grains. The nature of the CeO2 promoting densification lies in the substitution and solution with CaO. Ce4+ approaches into CaO lattices, which enlarges the vacancy concentration of Ca2+ and accelerates the diffusion of Ca2+.

Effect of sulfation on the surface activity of CaO for N2O decomposition

International Nuclear Information System (INIS)

Wu, Lingnan; Hu, Xiaoying; Qin, Wu; Dong, Changqing; Yang, Yongping

2015-01-01

Graphical abstract: - Highlights: • Sulfation of CaO (1 0 0) surface greatly deactivates its surface activity for N 2 O decomposition. • An increase of sulfation degree leads to a decrease of CaO surface activity for N 2 O decomposition. • Sulfation from CaSO 3 into CaSO 4 is the crucial step for deactivating the surface activity for N 2 O decomposition. • The electronic interaction CaO (1 0 0)/CaSO 4 (0 0 1) interface is limited to the bottom layer of CaSO 4 (0 0 1) and the top layer of CaO (1 0 0). • CaSO 4 (0 0 1) and (0 1 0) surfaces show negligible catalytic ability for N 2 O decomposition. - Abstract: Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N 2 O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N 2 O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N 2 O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO 2 or SO 3 molecule forms stable local CaSO 3 or CaSO 4 on the CaO (1 0 0) surface with strong hybridization between the S atom of SO x and the surface O anion. The formed local CaSO 3 increases the barrier energy of N 2 O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO 4 remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO 3 into CaSO 4 is therefore the crucial step for deactivating the surface activity for N 2 O decomposition. Completely sulfated CaSO 4 (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO 4 for N 2 O decomposition.

17 CFR 240.15b9-2 - Exemption from SRO membership for OTC derivatives dealers.

Science.gov (United States)

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Exemption from SRO membership for OTC derivatives dealers. 240.15b9-2 Section 240.15b9-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934...

Ocenění závodu Automotive Lighting s.r.o.

OpenAIRE

Přibyl, Matěj

2012-01-01

The final thesis "Business valuation of the company Automotive Lighting s.r.o." is divided into the theoretical and the practical part. The theoretical part is first focused on general issues of valuation. Its following parts then theoretically describe the general method of business valuation. The practical part is dedicated to the application of methods described in the theoretical part. Only the discounted cash flow to equity method (representing income valuation methods) and the EV/EBITDA...

Analýza makroprostředí firmy VLAMA s.r.o.

OpenAIRE

VORLÍČKOVÁ, Jana

2010-01-01

The aim of this bachelor work "Analysis of the macroenvironment of the company VLAMA s.r.o." is to identify factors of macroenvironment that have direct impact on the company by the means of STEP analysis. Furthermore the current situation of the company is evaluated by the means of SWOT analysis. On the basis of results from both carried out analyses and obtained information the changes that would lead to improvement of current status are suggested.

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...

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.

A comparative analysis of response to ORS (oral rehydration solution vs. ORS + gelatin tannate in two cohorts of pediatric patients with acute diarrhea Análisis comparativo de dos cohortes de pacientes pediátricos con diarrea aguda y respuesta a la solución de rehidratación oral (SRO frente a SRO + tanato de gelatina

Directory of Open Access Journals (Sweden)

J. Esteban Carretero

2009-01-01

Full Text Available Aim: the study aims to observe the response to treatment with ORS only or ORS + gelatin tannate in two cohorts of pediatric patients with acute diarrhea, with the primary efficacy endpoint being the number of stools at 12 hours from baseline. Methods: children aged 3 months to 12 years were included in the study. Only children with acute diarrhea, more than 3 liquid stools, and duration inferior to 72 h were included. Number of stools was recorded as absolute number, categorized as ≤ 3 and ≥ 4 stools over 12 hours, and as a stool decrease index (SDI. Other clinical variables were recorded, including weight, fever, vomiting, stool characteristics, and signs of peritonitis/sepsis. Results: baseline characteristics for the two populations included a mean age of 2.3 years in the ORS group and 2.6 years in the ORS + gelatin tannate group. Children younger than 2 years represented 59.8 and 54.3% in the ORS and ORS + gelatin tannate groups, respectively. Clinical variables such as vomiting, dehydration, weigth, and stool decrease index were used to compare the two groups. We found a statistical significant difference between the two groups (p Objetivo: el estudio tiene como objetivo observar la respuesta al tratamiento con SRO o SRO + tanato de gelatina en dos cohortes de pacientes pediátricos que presentan diarrea aguda, siendo el número de deposiciones a las 12 horas desde el tratamiento inicial el criterio principal de valoración de la eficacia. Métodos: en el estudio se incluyeron niños de entre 3 meses y 12 años de edad. Únicamente se incluyeron niños con diarrea aguda, con más de 3 deposiciones líquidas y menos de 72 horas de evolución. Se registró la variable principal del número de deposiciones y de análisis como número absoluto, categorizado como ≤ 3 y ≥ 4 deposiciones en 12 horas y como un índice de disminución de deposiciones (IDD. Se registraron otras variables clínicas como peso, fiebre, vómitos, caracter

A room of one's own: the SRO and the single elderly.

Science.gov (United States)

Crystal, S; Beck, P

1992-10-01

A survey of 485 single-room occupancy housing (SRO) residents in New York City found elderly residents strongly preferred to remain in centrally located neighborhoods where apartment housing was beyond their means; did not wish to share a housing unit; and had little confidence that they could find acceptable housing if they lost their present unit. For many elderly residents, SROs meet needs not easily met by available alternatives. Results suggest the need to maintain this housing option for older persons and replace losses that have accompanied gentrification in many central city areas.

HIGHLY ACTIVE CaO FOR THE TRANSESTERIFICATION TO ...

African Journals Online (AJOL)

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1College of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an Shannxi, ... acid methyl esters (FAME) yield of the modified CaO was greatly enhanced ... same properties as diesel, to supply or replace such fossil fuel[1, 2].

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......-carbonating conditions, but no or even a negative effect under carbonating conditions. The results led to the conclusion that SO2 released from raw meal in the upper stages of the preheater does not to any significant extent react with CaO recirculating in the preheater tower....

Biomass gasification bottom ash as a source of CaO catalyst for biodiesel production via transesterification of palm oil

International Nuclear Information System (INIS)

Maneerung, Thawatchai; Kawi, Sibudjing; Wang, Chi-Hwa

2015-01-01

Highlights: • CaO catalyst was successfully developed from wood gasification bottom ash. • CaCO 3 in bottom ash can be converted to CaO catalyst by calcination. • CaO catalysts derived from bottom ash exhibited high activity towards transesterification. • CaO catalysts derived from bottom ash can be reutilized up to four times. - Abstract: The main aim of this research is to develop environmentally and economically benign heterogeneous catalysts for biodiesel production via transesterification of palm oil. For this propose, calcium oxide (CaO) catalyst has been developed from bottom ash waste arising from woody biomass gasification. Calcium carbonate was found to be the main component in bottom ash and can be transformed into the active CaO catalyst by simple calcination at 800 °C without any chemical treatment. The obtained CaO catalysts exhibit high biodiesel production activity, over 90% yield of methyl ester can be achieved at the optimized reaction condition. Experimental kinetic data fit well the pseudo-first order kinetic model. The activation energy (E a ) of the transesterification reaction was calculated to be 83.9 kJ mol −1 . Moreover, the CaO catalysts derived from woody biomass gasification bottom ash can be reutilized up to four times, offering the efficient and low-cost CaO catalysts which could make biodiesel production process more economic and environmental friendly

Spectroscopic, thermal, and electrical properties of MgO/ polyvinyl pyrrolidone/ polyvinyl alcohol nanocomposites

Science.gov (United States)

Mohammed, Gh.; El Sayed, Adel M.; Morsi, W. M.

2018-04-01

In this study, we aimed to control the optical and electrical properties of polyvinyl alcohol (PVA) in order to broaden its industrial and technological applications, which we achieved by blending PVA with polyvinyl pyrrolidone (PVP) and adding sol-gel prepared MgO nanopowder. The blended film and nanocomposite films were prepared using the solution casting technique. X-ray diffraction analyses showed that the crystallite size was ∼18.4 nm for MgO and the highest degree of crystallinity (XC) in the films was about 24.34% at 1.0 wt% MgO. High resolution transmission electron microscopy determined the nanoribbon morphology of MgO. Scanning electron microscopy (SEM) indicated the uniform distribution of the MgO nanoribbons on the surfaces of the PVA/PVP films. SEM and Fourier transform infrared spectroscopy also confirmed the interaction between the blend and MgO fillers. The effects of the additives on the glass transition (Tg) and melting (Tm) temperatures were evaluated by differential thermal analysis and differential scanning calorimetry. The appearance of one melting point confirmed the miscibility of the two polymers. According to ultraviolet-visible-near infrared spectroscopy measurements, the optical properties and optical constants of PVA could be adjusted by the addition of PVP and MgO, where the optical band gap (Eg) determined for PVA increased with the PVP content, whereas it decreased to 4.8 eV as the MgO content increased. The DC conductivity (σdc) of the films increased whereas the activation energy (Ea) decreased after the addition of MgO, possibly because the nanoribbon shape fixed the preferred conducting pathways. In addition, MgO could break the H-bond in sbnd OH groups of the blends to allow the free movement of the molecular chains.

Point defects and magnetic properties of neutron irradiated MgO single crystal

Directory of Open Access Journals (Sweden)

Mengxiong Cao

2017-05-01

Full Text Available (100-oriented MgO single crystals were irradiated to introduce point defects with different neutron doses ranging from 1.0×1016 to 1.0×1020 cm-2. The point defect configurations were studied with X-ray diffuse scattering and UV-Vis absorption spectra. The isointensity profiles of X-ray diffuse scattering caused by the cubic and double-force point defects in MgO were theoretically calculated based on the Huang scattering theory. The magnetic properties at different temperature were measured with superconducting quantum interference device (SQUID. The reciprocal space mappings (RSMs of irradiated MgO revealed notable diffuse scattering. The UV-Vis spectra indicated the presence of O Frenkel defects in irradiated MgO. Neutron-irradiated MgO was diamagnetic at room temperature and became ferromagnetic at low temperature due to O Frenkel defects induced by neutron-irradiation.

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...

The AtCAO gene, encoding chlorophyll a oxygenase, is required for chlorophyll b synthesis in Arabidopsis thaliana

Science.gov (United States)

Espineda, Cromwell E.; Linford, Alicia S.; Devine, Domenica; Brusslan, Judy A.

1999-01-01

Chlorophyll b is synthesized from chlorophyll a and is found in the light-harvesting complexes of prochlorophytes, green algae, and both nonvascular and vascular plants. We have used conserved motifs from the chlorophyll a oxygenase (CAO) gene from Chlamydomonas reinhardtii to isolate a homologue from Arabidopsis thaliana. This gene, AtCAO, is mutated in both leaky and null chlorina1 alleles, and DNA sequence changes cosegregate with the mutant phenotype. AtCAO mRNA levels are higher in three different mutants that have reduced levels of chlorophyll b, suggesting that plants that do not have sufficient chlorophyll b up-regulate AtCAO gene expression. Additionally, AtCAO mRNA levels decrease in plants that are grown under dim-light conditions. We have also found that the six major Lhcb proteins do not accumulate in the null ch1-3 allele. PMID:10468639

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. Copyright © 2013 Elsevier B.V. All rights reserved.

Incorporating IGCC and CaO sorption-enhanced process for power generation with CO2 capture

International Nuclear Information System (INIS)

Chen, Shiyi; Xiang, Wenguo; Wang, Dong; Xue, Zhipeng

2012-01-01

Highlights: ► CaO sorption-enhanced process is incorporated with IGCC for CO 2 capture. ► IGCC–CCS is simplified using CaO sorption-enhanced process. ► The electricity efficiency is around 31–33% and CO 2 capture efficiency exceeds 95%. ► Parameters such as sorption pressure influence the system performance. -- Abstract: Integrated gasification combined cycle (IGCC) is a power generation technology to convert solid fuels into electricity. IGCC with CCS is regarded as a promising option to mitigate CO 2 emission. In this paper, the CaO sorption-enhanced process is incorporated downstream with coal gasification to produce a hydrogen-rich stream for electricity production and CO 2 separation. A WGS-absorber substitutes the high- and low-temperature water–gas shift reactors and desulfurization units in conventional IGCC–CCS to produce a hydrogen-rich stream, which is sent onto a gas turbine. CaO is used as the sorbent to enhance hydrogen production and for CO 2 capture. Regeneration of CaO is completed via calcination in a regenerator vessel. The IGCC with CaO sorption-enhanced process is modeled and simulated using Aspen Plus software. Two commercial available gasification technologies, Shell and Texaco, are integrated with the sorption-enhanced process. The results showed IGCC with CaO sorption-enhanced process has a satisfactory system performance. Even though the net electricity efficiency is not as high as expected, just around 30–33%, the system has a high CO 2 capture efficiency ∼97% and low pollutant emissions. Moreover, compared with conventional IGCC–CCS, the schematic diagram of the IGCC–CCS process is simplified. Parameters that affect the plant performance are analyzed in the sensitive analysis, including WGS-absorber temperature, H 2 O/CO ratio, pressure, etc. Some challenges to the system are also discussed.

Carbothermal preparation of Si2N2O powder

NARCIS (Netherlands)

Bolech, M.; Metselaar, R.; van Dijen, F.K.; Blömer, F.; With, de G.; Ramaekers, P.P.J.; Vincenzini, P.

1987-01-01

At temperatures 1400 - 1450 °C silicon oxynitride powder can be produced from silica/carbon mixtures with a molar ratio 2/3 under a nitrogen flow. The conversion rate is considerably exhanced by the presence of oxide additions like CaO, BaO and SrO, which form a liquid phase with silica at the

Caso e caos

CERN Document Server

Ruelle, David

1992-01-01

Caso e caos – Il caso ha la sua ragione. Ma quale? E cos’è in realtà il caso? Da dove viene e come può fare irruzione nella nostra descrizione dell’universo? A tutte queste domande, in una chiara e lucida esposizione, cerca di dare risposta David Ruelle. Curiosando tra i risultati scientifici del XX secolo e soffermandosi anche su fenomeni e problemi estranei alla scienza tradizionale – le lotterie, gli oroscopi, la teoria dei giochi, la genesi della turbolenza – Ruelle ci guida a conoscere il caso avendo la matematica, la fisica e tutte le scienze naturali come compagne. Ancora oggi il modo in cui il caso irrompe nelle nostre vite e nel mondo può essere un mistero, ma grazie ai progressi della scienza, qui raccontati, riusciamo a saperne un poco di più.

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.

Hydrolysis of molten CaCl2-CaF2 with additions of CaO

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Espen Olsen

2017-10-01

Full Text Available Calcium halide based molten salts have recently attracted interest for a number of applications such as direct reduction of oxides for metal production and as liquefying agent in cyclic sorption processes for CO2 by CaO from dilute flue gases (Ca-looping. A fundamental aspect of these melts is the possible hydrolysis reaction upon exposure to gaseous H2O forming corrosive and poisonous hydrogen halides. In this work experiments have been performed investigating the formation of HCl and HF from a molten salt consisting of a 13.8 wt% CaF2 in CaCl2 eutectic exposed to a flowing gas consisting of 10 vol% H2O in N2. Hydrolysis has been investigated as function of content of CaO and temperature. HCl and HF are shown to be formed at elevated temperatures; HCl forms to a substantially larger extent than HF. Addition of CaO has a marked, limiting effect on the hydrolysis. Thermodynamic modeling of the reaction indicates activity coefficients for CaO above unity in the system. For cyclic CO2-capture based on thermal swing, it is advisable to keep the temperature in the carbonation (absorption reactor well below 850 ℃ while maintaining a high CaO content if molten CaCl2 is employed. Similar conclusions can be drawn with regards to CaF2.

Ex Isto, de Cao Guimarães, e o ultrapassamento de si

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Rafael de Almeida

2014-12-01

Full Text Available Ex It, by Cao Guimarães, and the transcendence of self – This essay focuses on the film Ex It (2010, by Cao Guimarães, with emphasis on an analysis of how the actor transcends himself to give shape to the existence of the image of the real character he interprets, and the way in which the film develops, passing from literature to cinema, documentary to fiction, and life to image.

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)

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

International Nuclear Information System (INIS)

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

2013-01-01

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 H 2 O precursors. MgO thin films are deposited on both HF-last Si(1 0 0) and SiO 2 /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. (paper)

Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

Science.gov (United States)

Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

2017-04-01

There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

Untitled

Indian Academy of Sciences (India)

and BiO pyramidal units are present depending on compositions. In these glasses with increasing SrO and CaO contents, a conversion of BiO units to BiO units was observed producing nonbridging oxygen atoms, For the PbO-CuO glasses, IR bands have been observed at 830cm, 620 cm and 460 cm corresponding to.

The effect of impurities on the electronic properties of MgO

Energy Technology Data Exchange (ETDEWEB)

Jalili, Seifollah [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: sjalili@nano.ipm.ac.ir; Majidi, Roya [Department of Physics, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

2008-10-01

The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively.

The effect of impurities on the electronic properties of MgO

International Nuclear Information System (INIS)

Jalili, Seifollah; Majidi, Roya

2008-01-01

The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively

Analýza okolí podniku Camaieu česká, s.r.o.

OpenAIRE

Votočková, Iveta

2014-01-01

The thesis analyses environment of the company Camaieu česká, s.r.o., which carries on the retail sale of womenswear. The thesis is devided into theoretical and pracitcal. PESTLE analysis is used to examine the macroenvironment and Porter five forces analysis is used to examine the microenvironment. The SWOT analysis combines analysis of internal and external environment of the company. The main purpose of this thesis si to describe factors, which affecting the company.

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.

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.

Finanční analýza společnosti Nestlé Česko, s.r.o.

OpenAIRE

Hoskovcová, Eva

2008-01-01

This work analyzes financial situation of the company Nestlé Česko, s.r.o. on the basis of financial reports of the period 2003 - 2007. Methodological part describes methods of financial analysis, which are applied in practical part. Conclusion summarizes findings executed in practical part.

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?

Correlation between ferromagnetism and defects in MgO nanocrystals studied by positron annihilation

International Nuclear Information System (INIS)

Wang, D.D.; Chen, Z.Q.; Li, C.Y.; Li, X.F.; Cao, C.Y.; Tang, Z.

2012-01-01

High purity MgO nanopowders were pressed into pellets and annealed in air from 100 to 1400 °C. Variation of the microstructures was investigated by X-ray diffraction and positron annihilation spectroscopy. Annealing induces an increase in the MgO grain size from 27 to 60 nm with temperature increasing up to 1400 °C. Positron annihilation measurements reveal vacancy defects including Mg vacancies, vacancy clusters, microvoids and large pores in the grain boundary region. Rapid recovery of Mg monovacancies and vacancy clusters was observed after annealing above 1200 °C. Room temperature ferromagnetism was observed for MgO nanocrystals annealed at 100, 700, and 1000 °C. However, after 1400 °C annealing, MgO nanocrystals turn into diamagnetic. Our results suggest that the room temperature ferromagnetism in MgO nanocrystals might originate from the interfacial defects.

Correlation between ferromagnetism and defects in MgO nanocrystals studied by positron annihilation

Science.gov (United States)

Wang, D. D.; Chen, Z. Q.; Li, C. Y.; Li, X. F.; Cao, C. Y.; Tang, Z.

2012-07-01

High purity MgO nanopowders were pressed into pellets and annealed in air from 100 to 1400 °C. Variation of the microstructures was investigated by X-ray diffraction and positron annihilation spectroscopy. Annealing induces an increase in the MgO grain size from 27 to 60 nm with temperature increasing up to 1400 °C. Positron annihilation measurements reveal vacancy defects including Mg vacancies, vacancy clusters, microvoids and large pores in the grain boundary region. Rapid recovery of Mg monovacancies and vacancy clusters was observed after annealing above 1200 °C. Room temperature ferromagnetism was observed for MgO nanocrystals annealed at 100, 700, and 1000 °C. However, after 1400 °C annealing, MgO nanocrystals turn into diamagnetic. Our results suggest that the room temperature ferromagnetism in MgO nanocrystals might originate from the interfacial defects.

Effect of sulfation on the surface activity of CaO for N{sub 2}O decomposition

Energy Technology Data Exchange (ETDEWEB)

Wu, Lingnan, E-mail: wulingnan@126.com [School of Energy, Power and Mechanical Engineering, North China Electric Power University, 102206 Beijing (China); National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Hu, Xiaoying, E-mail: huxy@ncepu.edu.cn [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Qin, Wu, E-mail: qinwugx@126.com [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Dong, Changqing, E-mail: cqdong1@163.com [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Yang, Yongping, E-mail: yypncepu@163.com [School of Energy, Power and Mechanical Engineering, North China Electric Power University, 102206 Beijing (China)

2015-12-01

Graphical abstract: - Highlights: • Sulfation of CaO (1 0 0) surface greatly deactivates its surface activity for N{sub 2}O decomposition. • An increase of sulfation degree leads to a decrease of CaO surface activity for N{sub 2}O decomposition. • Sulfation from CaSO{sub 3} into CaSO{sub 4} is the crucial step for deactivating the surface activity for N{sub 2}O decomposition. • The electronic interaction CaO (1 0 0)/CaSO{sub 4} (0 0 1) interface is limited to the bottom layer of CaSO{sub 4} (0 0 1) and the top layer of CaO (1 0 0). • CaSO{sub 4} (0 0 1) and (0 1 0) surfaces show negligible catalytic ability for N{sub 2}O decomposition. - Abstract: Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N{sub 2}O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N{sub 2}O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N{sub 2}O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO{sub 2} or SO{sub 3} molecule forms stable local CaSO{sub 3} or CaSO{sub 4} on the CaO (1 0 0) surface with strong hybridization between the S atom of SO{sub x} and the surface O anion. The formed local CaSO{sub 3} increases the barrier energy of N{sub 2}O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO{sub 4} remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO{sub 3} into CaSO{sub 4} is therefore the crucial step for deactivating the surface activity for N{sub 2}O decomposition. Completely sulfated CaSO{sub 4} (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO{sub 4} for N{sub 2}O decomposition.

X-ray fluorescence spectrometry of Al, Mg, Ca, Fe, S in solid phase of magnesite technology of combustion product desulfurization

International Nuclear Information System (INIS)

Vymola, R.; Hora, V.; Spitzer, Z.

1989-01-01

Solid phase samples of magnesite technology were moulded into pellets or melted into the shape of a glass disk. MgO, CaO, Fe 2 O 3 , S, Al 2 O 3 and SiO 2 were determined in the samples by X-ray fluorescence analysis. Fluorescence intensities were measured with an SRS 200 sequential X-ray spectrometer and the measured data were evaluated using a linked-up PDP 11/04 computer. The reproducibility of MgO, CaO, Fe 2 O 3 and S determinations was very good; higher measurement accuracy was achieved for moulded samples. The specificity of determinations was checked by a comparative chemical analysis. (E.J.). 8 tabs., 5 refs

Dependence of magnetic anisotropy on MgO sputtering pressure in Co20Fe60B20/MgO stacks

Science.gov (United States)

Kaidatzis, A.; Serletis, C.; Niarchos, D.

2017-10-01

We investigated the dependence of magnetic anisotropy of Ta/Co20Fe60B20/MgO stacks on the Ar partial pressure during MgO deposition, in the range between 0.5 and 15 mTorr. The stacks are studied before and after annealing at 300°C and it is shown that magnetic anisotropy significantly depends on Ar partial pressure. High pressure results in stacks with very low perpendicular magnetic anisotropy even after annealing, while low pressure results in stacks with perpendicular anisotropy even at the as-deposited state. A monotonic increase of magnetic anisotropy energy is observed as Ar partial pressure is decreased.

Silicothermic reduction of MgO using diode laser: Experimental and kinetic study

Directory of Open Access Journals (Sweden)

M.S. Mahmoud

2017-12-01

Full Text Available As a step toward realizing magnesium civilization, which needs a sustainable Mg production process, the reduction of MgO to Mg has been investigated. Direct diode laser (DDL produces high power and continuous beam in tiny spots. The laser with energy density up to 83*105 W/cm2 is focused on MgO/Si target inside the vacuum chamber, creating the high temperature zone, which stimulates the Mg production reaction. The vapor is collected on the copper plate; and then, analyzed chemically in terms of Mg production efficiency. The largest reduction and energy efficiencies in Ar atmosphere were 41% and 15.3 mg kJ−1, while in the vacuum, 13.5% and 15.8 mg kJ−1 were attainable. The reactions of MgO and Si have been investigated. Calculations revealed that the MgO reduction with Si proceeds as heterogeneous reaction. The rate of reaction of Si with MgO is faster than the rate of MgO evaporation and Mg vapor deposition.

Unequally redundant RCD1 and SRO1 mediate stress and developmental responses and interact with transcription factors

NARCIS (Netherlands)

Jaspers, P.; Blomster, T.; Brosché, M.; Salojärvi, J.; Ahlfors, R.; Vainonen, J.P.; Reddy, R.A.; Immink, G.H.; Angenent, G.C.; Turck, F.; Overmyer, K.; Kangasjärvi, J.

2009-01-01

RADICAL-INDUCED CELL DEATH1 (RCD1) is an important regulator of stress and hormonal and developmental responses in Arabidopsis thaliana. Together with its closest homolog, SIMILAR TO RCD-ONE1 (SRO1), it is the only Arabidopsis protein containing the WWE domain, which is known to mediate

Correlation between ferromagnetism and defects in MgO nanocrystals studied by positron annihilation

Energy Technology Data Exchange (ETDEWEB)

Wang, D.D. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Chen, Z.Q., E-mail: chenzq@whu.edu.cn [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Li, C.Y.; Li, X.F. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Cao, C.Y.; Tang, Z. [Department of Electronic and Engineering, East China Normal University, Shanghai 200241 (China)

2012-07-15

High purity MgO nanopowders were pressed into pellets and annealed in air from 100 to 1400 Degree-Sign C. Variation of the microstructures was investigated by X-ray diffraction and positron annihilation spectroscopy. Annealing induces an increase in the MgO grain size from 27 to 60 nm with temperature increasing up to 1400 Degree-Sign C. Positron annihilation measurements reveal vacancy defects including Mg vacancies, vacancy clusters, microvoids and large pores in the grain boundary region. Rapid recovery of Mg monovacancies and vacancy clusters was observed after annealing above 1200 Degree-Sign C. Room temperature ferromagnetism was observed for MgO nanocrystals annealed at 100, 700, and 1000 Degree-Sign C. However, after 1400 Degree-Sign C annealing, MgO nanocrystals turn into diamagnetic. Our results suggest that the room temperature ferromagnetism in MgO nanocrystals might originate from the interfacial defects.

Finanční analýza podniku Matex HK s.r.o.

OpenAIRE

Matyáš, Petr

2009-01-01

Financial analysis of company is very important instrument of corporate affairs. My work deals with complex financial analysis of company Matex HK s.r.o. since 2004 till 2008. I primarily focus on horizontal and vertical analysis, ration and distance indicators analysis, EVA analysis, ROE analysis and I discover by the help of models of bankruptcy if company is threatened by bankrupt. I judge too, if company is run by some recommended rules, example by gold balance rules. Next I accentuate on...

Synergistic pretreatment of waste activated sludge using CaO_2 in combination with microwave irradiation to enhance methane production during anaerobic digestion

International Nuclear Information System (INIS)

Wang, Jie; Li, Yongmei

2016-01-01

Highlights: • CaO_2/MW pretreatment synergistically enhanced WAS solubilization and CH_4 production. • MW irradiation facilitated more "·OH generation from CaO_2. • The optimal pretreatment condition for methane production was determined. • The growths of both hydrogenotrophic and acetate-utilizing methanogens were promoted. • The dewaterability of WAS was improved considerably by CaO_2/MW treatment. - Abstract: To investigate the effects of combined calcium peroxide (CaO_2) and microwave pretreatment on anaerobic digestion of waste activated sludge, lab-scale experiments were conducted to measure the solubilization, biodegradation, and dewaterability of the waste activated sludge. Additionally, the synergistic effects between CaO_2 and microwave were studied, and the microbial activity and methanogenic archaea community structure were analyzed. Combined pretreatment considerably facilitated the solubilization and subsequent anaerobic digestion of the waste activated sludge. The optimal pretreatment condition was CaO_2 (0.1 g/gVSS)/microwave (480 W, 2 min) for methane production during the subsequent anaerobic digestion process. Under this condition, 80.2% higher CH_4 accumulation yield was achieved after 16 d of anaerobic digestion when compared with the control. The synergistic effects of CaO_2/microwave pretreatment resulted from the different mechanisms of CaO_2 and microwave treatments. Further, microwave irradiation increased "·OH generation from CaO_2 and significantly alleviated the inhibitory effect of CaO_2 on methanogens. The activities of hydrolytic enzymes and acid-forming enzymes in the waste activated sludge were improved after CaO_2 (0.1 g/gVSS)/microwave (480 W, 2 min) pretreatment. Methanogenesis enzyme activity was also higher after CaO_2 treatment (0.1 g/gVSS)/microwave (480 W, 2 min) following a lag period. Illumina MiSeq sequencing analysis indicated that acetate-utilizing methanogen (Methanosaeta sp.) and H_2/CO_2-utilizing

MgO magnetic tunnel junctions of enduring F-type upon annealing

International Nuclear Information System (INIS)

Schleicher, F; Halisdemir, U; Urbain, E; Gallart, M; Boukari, S; Beaurepaire, E; Gilliot, P; Bowen, M; Lacour, D; Montaigne, F; Hehn, M

2015-01-01

The authors performed magnetotransport experiments to determine whether annealing alters the oxygen vacancy-mediated tunnelling potential landscape of the central portion of a MgO ultrathin film within sputtered CoFeB/MgO/CoFeB magnetic tunnel junctions. Using the Î rel method reveals a temperature-dependent tunnelling barrier height for a non-annealed barrier that arises from single oxygen vacancies (F centres) and is qualitatively identical to that found for its partly and fully annealed counterparts. Thus these MTJs with F centres remain of F-type upon annealing. This explicitly confirms that the large tunnel-magnetoresistance (TMR) increase upon annealing results mainly from structural modifications of MgO and CoFeB and not from vacancy pairing within the barrier. Photoluminescence spectra performed on both annealed and non-annealed thin MgO films grown on CoFeB electrodes support this conclusion. This work should promote renewed scrutiny over the precise impact of annealing on tunnelling magnetotransport across MgO. (paper)

Dislocations and Plastic Deformation in MgO Crystals: A Review

Directory of Open Access Journals (Sweden)

Jonathan Amodeo

2018-05-01

Full Text Available This review paper focuses on dislocations and plastic deformation in magnesium oxide crystals. MgO is an archetype ionic ceramic with refractory properties which is of interest in several fields of applications such as ceramic materials fabrication, nano-scale engineering and Earth sciences. In its bulk single crystal shape, MgO can deform up to few percent plastic strain due to dislocation plasticity processes that strongly depend on external parameters such as pressure, temperature, strain rate, or crystal size. This review describes how a combined approach of macro-mechanical tests, multi-scale modeling, nano-mechanical tests, and high pressure experiments and simulations have progressively helped to improve our understanding of MgO mechanical behavior and elementary dislocation-based processes under stress.

La2O3/CaO CATALYSTS AND ITS APPLICATION IN THE OXIDATIVE COUPLING OF METHANE

OpenAIRE

Garrido-Schaeffer, A.; Dedios Yenque, G.; Ponce Alvaréz, S.

2014-01-01

La2O3/CaO catalysts were prepared at different weight percentages of La2O3.Por the coprecipitation method described porRaO, CaCO3 is prepared and then it was impregnated in a solution of La (NO) 3.6H2O thus obtaining the catalyst precursor . precursors dried at 393K and calcined at 973K, obtaining 0-15% La2O3/CaO catalysts. XRF elemental qualitative analysis was performed. By FTIR carbonates adsorbed species was observed. The presence of La2O3 and CaO phases was confirmed by XRD and BET surfa...

Tuning the properties of an MgO layer for spin-polarized electron transport

Science.gov (United States)

Zhao, Chong-Jun; Ding, Lei; Zhao, Zhi-Duo; Zhang, Peng; Cao, Xing-Zhong; Wang, Bao-Yi; Zhang, Jing-Yan; Yu, Guang-Hua

2014-08-01

The influence of substrate temperature and annealing on quality/microstructural evolution of MgO, as well as the resultant magnetoresistance (MR) ratio, has been investigated. It has been found that the crystallinity of MgO in the MgO/NiFe/MgO heterostructures gradually improves with increasing substrate temperature. This behavior facilitates the transport of spin-polarized electrons, resulting in a high MR value. After annealing, the formation of vacancy clusters in MgO layers observed through positron annihilation spectroscopy leads to an increase in MR at different levels because of the crystallinity improvement of MgO. However, these vacancy clusters as another important defect can limit further improvement in MR.

Training nuclear power plant personnel on SR-O reactor

International Nuclear Information System (INIS)

Cerny, K.; Boucek, F.; Kveton, M.; Prokopec, Z.; Fleischhans, J.

1983-01-01

The SR-O reactor is an experimental pool-type reactor with a maximum output of 1 MW and maximum thermal neutron flux density of 5.3x10 13 m -2 s -1 . The reactor is described in detail and its specifications are given. The protection and control systems of the reactor permit both manual and automatic operation. The reactor is used for training courses for nuclear power plant operators and for post-graduate study courses for other specialists. Intensive courses for 4 to 6 persons take 15 to 20 days. The course is adjusted to the results of introductory theoretical tests. An optimal teaching method has been developed based on the flowchart algorithmic method, dividing activities into operations (manipulations with controls, issuing commands, making records, etc.) and decision making (information reception and processing). (M.D.)

Functionalized inorganic membranes for gas separation

Science.gov (United States)

Ku, Anthony Yu-Chung [Rexford, NY; Ruud, James Anthony [Delmar, NY; Molaison, Jennifer Lynn [Marietta, GA; Schick, Louis Andrew ,; Ramaswamy, Vidya [Niskayuna, NY

2008-07-08

A porous membrane for separation of carbon dioxide from a fluid stream at a temperature higher than about 200.degree. C. with selectivity higher than Knudsen diffusion selectivity. The porous membrane comprises a porous support layer comprising alumina, silica, zirconia or stabilized zirconia; a porous separation layer comprising alumina, silica, zirconia or stabilized zirconia, and a functional layer comprising a ceramic oxide contactable with the fluid stream to preferentially transport carbon dioxide. In particular, the functional layer may be MgO, CaO, SrO, BaO, La.sub.2O.sub.3, CeO.sub.2, ATiO.sub.3, AZrO.sub.3, AAl.sub.2O.sub.4, A.sup.1FeO.sub.3, A.sup.1MnO.sub.3, A.sup.1CoO.sub.3, A.sup.1NiO.sub.3, A.sup.2HfO.sub.3, A.sup.3CeO.sub.3, Li.sub.2ZrO.sub.3, Li.sub.2SiO.sub.3, Li.sub.2TiO.sub.3 or a mixture thereof; wherein A is Mg, Ca, Sr or Ba; A.sup.1 is La, Ca, Sr or Ba; A.sup.2 is Ca, Sr or Ba; and A.sup.3 is Sr or Ba.

Effect of NiO growth conditions on the bipolar resistance memory switching of Pt/NiO/SRO structure

International Nuclear Information System (INIS)

Kurnia, F.; Hadiyawarman, H.; Jung, C. U.; Liu, C. L.; Lee, S. B.; Yang, S. M.; Park, H. W.; Song, S. J.; Hwang, C. S.

2010-01-01

We deposited NiO thin films with SrRuO 3 bottom electrodes on SrTiO 3 (001) substrates by using pulsed laser deposition. The growth temperature and the oxygen pressure were varied in order to obtain NiO films with different structural and electrical properties. We investigated the I-V characteristics of the Pt/NiO/SRO structures and observed a strong dependence of bipolar resistance switching on the growth conditions of the NiO thin films. Stable bipolar memory resistance switching was observed only in the devices with NiO films deposited at 400 .deg. C and 10 mTorr of O 2 . The off-state I-V curve of bipolar switching showed a linear fitting to the Schottky effect, indicating its origin in the NiO/SRO interface. Our results suggest that the growth conditions of NiO may affect the bipolar switching behavior through the film's resistance, the film's crystallinity, or the status of the grain boundaries.

Behaviour of CaO coating of gas atomized Mg powders using mechanical milling process

International Nuclear Information System (INIS)

Kim, Sun-Mi; Kim, Yong Hwan; Kim, Young Do; Kim, Taek-Soo

2011-01-01

Highlights: → This work is very new, since behaviour of CaO coating with milling time as desulfurizer is not frequently reported. → The manuscript reports the new manner of Mg powders desulfurizer development by the innovative process. - Abstract: In order to synthesize a thermally stable Mg powder as a desulfurizer of iron, pure Mg was gas atomized to powders and coated by CaO powders, to produce a thermally stable desulfurizer using a mechanical milling process. Since the effect of desulfurization is dependent on the degree of surface modification, coating behaviours such as the size, morphology and layer thickness were investigated as a function of milling condition. As the milling conducted from 10 min to 30 min, 1 h, 3 h, 6 h, 12 h, CaO particles began to stick on the surface of Mg powders. The layer of CaO formed from 1 h milling was about 17 μm thick and gradually thickened to be 28 μm, 32 μm and 37 μm with increasing the milling time to 3 h, 6 h and 12 h, respectively. The shape of coated powder became more spherical after 1 h milling, being mostly spherical after 6 h. Desulfurization rate and uniformity were evaluated for the various thickness of the coating layer.

Structural, optical and magnetic characterizations of Mn-doped MgO nanoparticles

International Nuclear Information System (INIS)

Azzaza, S.; El-Hilo, M.; Narayanan, S.; Judith Vijaya, J.; Mamouni, N.; Benyoussef, A.; El Kenz, A.; Bououdina, M.

2014-01-01

Structural, optical and room temperature magnetic properties of Mn-doped MgO nanoparticles with Mn fractions (5–50 at.%), were investigated. The as-prepared pure MgO, with grain size of about 15 nm, exhibits two magnetization components, one is diamagnetic and another is superparamagnetic. After removing the diamagnetic contribution, the magnetization curve exhibits superparamagnetic behavior which may be attributed to vacancy defects. As the Mn content increases, the lattice parameter decreases, the ferromagnetism appears and the emission bands were considerably blue shifted. First principle electronic structure calculations reveal the decrease of both the gap and the Curie temperature with increasing Mn concentration. The obtained results suggest that both Mn doping and oxygen vacancies play an important role in the development of room temperature ferromagnetism. - Graphical abstract: The measured room temperature magnetization curve for the Mn doped MgO with 5 at.%, 10 at.% and 20 at.%. - Highlights: • Combination of experimental and calculation methods. • Decrease of both the gap and the Curie temperature with increasing Mn content. • Ferromagnetism in MgO originate from interactions between defects

Synthesis and characterization of isolated iron oxide nanoparticle dispersed in MgO matrix

International Nuclear Information System (INIS)

Choa, Y.-H.; Yang, J.-K.; Yang, W.-J.; Auh, K.-H.

2003-01-01

γ-Fe 2 O 3 /MgO nanocomposite powders, which can be used for biomedical, magnetic and the catalytic applications, were fabricated by means of spray pyrolysis using an ultrasonic atomizer. The liquid source was prepared using Fe and Mg nitrates dissolved in pure water. The liquid was atomized using an ultrasonic atomizer and carried into a pre-heated chamber (500-800 deg. C) by air carrier gas. The mist was then decomposed into γ-Fe 2 O 3 and MgO nanopowders. The entire operation was performed at 1 atm. The γ-Fe 2 O 3 /MgO powder was found to be perfectly crystallized at 800 deg. C. The particle size of γ-Fe 2 O 3 /MgO nanocomposite powders prepared at 800 deg. C was about 10 nm for γ-Fe 2 O 3 and MgO, which were calculated by XRD using Scherrer's formula and measured by TEM observation. The samples indicate the presence of superparamagnetic properties and a blocking temperature (T B ) of 125 K

On the conductive properties of MgO films grown on ultrathin hexagonal close-packed Co(0001) layer

International Nuclear Information System (INIS)

Gladczuk, L.; Aleszkiewicz, M.

2013-01-01

Here we present a scanning tunneling microscopy study of electrical conductivity of (110)-oriented MgO ultrathin films grown on hexagonal close-packed Co(0001) surface by molecular beam epitaxy, being a good candidate for tunneling barrier for future-generation spintronic devices. Three-dimensional growth of the tunneling barrier, expected for compressive strains emerging at the Co/MgO interface, is demonstrated by reflection high-energy electron diffraction and atomic force microscopy. The 5 eV height of the full barrier of MgO is reached at a layer thickness of 4 nm. Thinner MgO layers exhibit randomly distributed spots of the high conductance on the tunneling current map. The current–voltage curves indicate the existence of vacancies in MgO crystal lattice, lowering the resistivity of the tunneling barrier. - Highlights: • Conductivity of MgO barrier in MgO/hexagonal close-packed-Co bilayer • Conductivity strongly varies with MgO thickness • MgO barrier exhibits randomly distributed spots of particularly high conductance • Tunneling current–voltage curves indicate the existence of vacancies in MgO lattice

Tunable reactivity of supported single metal atoms by impurity engineering of the MgO(001) support.

Science.gov (United States)

Pašti, Igor A; Johansson, Börje; Skorodumova, Natalia V

2018-02-28

Development of novel materials may often require a rational use of high price components, like noble metals, in combination with the possibility to tune their properties in a desirable way. Here we present a theoretical DFT study of Au and Pd single atoms supported by doped MgO(001). By introducing B, C and N impurities into the MgO(001) surface, the interaction between the surface and the supported metal adatoms can be adjusted. Impurity atoms act as strong binding sites for Au and Pd adatoms and can help to produce highly dispersed metal particles. The reactivity of metal atoms supported by doped MgO(001), as probed by CO, is altered compared to their counterparts on pristine MgO(001). We find that Pd atoms on doped MgO(001) are less reactive than on perfect MgO(001). In contrast, Au adatoms bind CO much more strongly when placed on doped MgO(001). In the case of Au on N-doped MgO(001) we find that charge redistribution between the metal atom and impurity takes place even when not in direct contact, which enhances the interaction of Au with CO. The presented results suggest possible ways for optimizing the reactivity of oxide supported metal catalysts through impurity engineering.

Incipient plasticity and indentation response of MgO surfaces using molecular dynamics

Science.gov (United States)

Tran, Anh-Son; Hong, Zheng-Han; Chen, Ming-Yuan; Fang, Te-Hua

2018-05-01

The mechanical characteristics of magnesium oxide (MgO) based on nanoindentation are studied using molecular dynamics (MD) simulation. The effects of indenting speed and temperature on the structural deformation and loading-unloading curve are investigated. Results show that the strained surface of the MgO expands to produce a greater relaxation of atoms in the surroundings of the indent. The dislocation propagation and pile-up for MgO occur more significantly with the increasing temperature from 300 K to 973 K. In addition, with increasing temperature, the high strained atoms with a great perturbation appearing at the groove location.

Physical and thermal behaviour of Sr-La-Al-B-Si based SOFC glass sealants as function of SrO content and B2O3/SiO2 ratio in the matrix

Science.gov (United States)

Ojha, Prasanta Kumar; Rath, S. K.; Chongdar, T. K.; Gokhale, N. M.; Kulkarni, A. R.

2011-05-01

A series of SOFC glass sealants with composition SrO (x), La2O3 (15), Al2O3 (15), B2O3 (40 - x), and SiO2 (30) [x = 10, 15, 20, 25 and 30] (wt.%) [SLABS] are investigated for their structure property correlations at different compositions. Quantitative Fourier transform infrared spectroscopy shows structural rigidity with increasing SrO content, as demonstrate by an increase in the Si-O-Si/O-Si-O bending and B-O-B stretching frequencies. The role of SrO as a modifier dominates the control of the structure and behaviour of glasses compared with the effect of network formers, i.e., the B2O3/SiO2 ratio. Consequent to the structural changes, increasing substitution of B2O3 by SrO the glasses causes increases in the density, glass transition temperature and dilatometric softening point. On the other hand, the crystallization temperatures show a decreasing trend and the coefficient of thermal expansion increases with increase in substitution.

Microstructure of pulsed-laser deposited PZT on polished and annealed MGO substrates

NARCIS (Netherlands)

King, S.L.; Coccia, L.G.; Gardeniers, Johannes G.E.; Boyd, I.W.

1996-01-01

Thin films of Lead-Zirconate-Titanate (PZT) have been grown by pulsed-laser-deposition (PLD) onto polished MgO substrates both with and without pre-annealing. The surface morphology of polished MgO substrates, which are widely used for deposition, is examined by AFM. Commercially available,

Reliability enhancement due to in-situ post-oxidation of sputtered MgO barrier in double MgO barrier magnetic tunnel junction

Directory of Open Access Journals (Sweden)

Chikako Yoshida

2017-06-01

Full Text Available We have investigated the effects of in-situ post-oxidation (PO of a sputtered MgO barrier in a double-MgO-barrier magnetic tunnel junction (MTJ and found that the short error rate was significantly reduced, the magnetoresistance (MR ratio was increased approximately 18%, and the endurance lifetime was extend. In addition, we found that the distribution of breakdown number (a measure of endurance exhibits trimodal characteristics, which indicates competition between extrinsic and intrinsic failures. This improvement in reliability might be related to the suppression of Fe and Co diffusion to the MgO barrier, as revealed by electron energy-loss spectroscopy (EELS analysis.

Kinetics of Roasting Decomposition of the Rare Earth Elements by CaO and Coal

Directory of Open Access Journals (Sweden)

Shuai Yuan

2017-06-01

Full Text Available The roasting method of magnetic tailing mixed with CaO and coal was used to recycle the rare earth elements (REE in magnetic tailing. The phase transformation and decomposition process were researched during the roasting processes. The results showed that the decomposition processes of REE in magnetic tailing were divided into two steps. The first step from 380 to 431 °C mainly entailed the decomposition of bastnaesite (REFCO3. The second step from 605 to 716 °C mainly included the decomposition of monazite (REPO4. The decomposition products were primarily RE2O3, Ce0.75Nd0.25O1.875, CeO2, Ca5F(PO43, and CaF2. Adding CaO could reduce the decomposition temperature of REFCO3 and REPO4. Meanwhile, the decomposition effect of CaO on bastnaesite and monazite was significant. Besides, the effects of the roasting time, roasting temperature, and CaO addition level on the decomposition rate were studied. The optimum technological conditions were a roasting time of 60 min; roasting temperature of 750 °C; and CaO addition level of 20% (w/w. The maximum decomposition rate of REFCO3 and REPO4 was 99.87%. The roasting time and temperature were the major factors influencing the decomposition rate. The kinetics process of the decomposition of REFCO3 and REPO4 accorded with the interfacial reaction kinetics model. The reaction rate controlling steps were divided into two steps. The first step (at low temperature was controlled by a chemical reaction with an activation energy of 52.67 kJ/mol. The second step (at high temperature was controlled by diffusion with an activation energy of 8.5 kJ/mol.

Influences of arc current on composition and properties of MgO thin films prepared by cathodic vacuum arc deposition

International Nuclear Information System (INIS)

Zhu Daoyun; Zheng Changxi; Wang Mingdong; Liu Yi; Chen Dihu; He Zhenhui; Wen Lishi; Cheung, W.Y.

2010-01-01

MgO thin films with high optical transmittances (more than 90%) were prepared by cathodic vacuum arc deposition technique. With the increase of arc current from 40 to 80 A, the deposition pressure decreases and the film thickness increases; the atomic ratio of Mg/O in MgO thin films (obtained by RBS) increases from 0.97 to 1.17, giving that deposited at 50 A most close to the stoichiometric composition of the bulk MgO; the grains of MgO thin films grow gradually as shown in SEM images. XRD patterns show that MgO (1 1 0) orientation is predominant for films prepared at the arc currents ranged from 50 to 70 A. The MgO (1 0 0) orientation is much enhanced and comparable to that of MgO (1 1 0) for films prepared at the arc current of 80 A. The secondary electron emission coefficient of MgO thin film increases with arc current ranged from 50 to 70 A.

Effect of stabilizer on optical and structural properties of MgO thin ...

Indian Academy of Sciences (India)

and are not easy to handle due to high moisture sensitivity. Metal salts include ... diethanolamine (DEA), triethanolamine (TEA) and acety- lacetone .... SEM analysis. Figure 9 shows SEM micrographs of MgO films prepared by three different sols. SEM micrographs of MgO thin films confirm difference between porosity of.

Stabilization of arsenic and lead by magnesium oxide (MgO) in different seawater concentrations.

Science.gov (United States)

Kameda, Kentaro; Hashimoto, Yohey; Ok, Yong Sik

2018-02-01

Ongoing sea level rise will have a major impact on mobility and migration of contaminants by changing a number of natural phenomena that alter geochemistry and hydrology of subsurface environment. In-situ immobilization techniques may be a promising remediation strategy for mitigating contaminant mobility induced by sea level rise. This study investigated the reaction mechanisms of magnesium oxide (MgO) with aqueous Pb and As under freshwater and seawater using XAFS spectroscopy. Initial concentrations of Pb and As in freshwater strongly controlled the characteristics of the reaction product of MgO. Our study revealed that i) the removal of aqueous Pb and As by MgO was increased by the elevation of seawater concentration, and ii) the removal of As was attributed primarily to (inner-sphere) surface adsorption on MgO, independent on seawater concentrations, and iii) the retention mechanism of Pb was dependent on seawater concentrations where formations of Pb oxides and adsorption on the MgO surface were predominant in solutions with low and high salinity, respectively. The release of As fixed with MgO significantly increased in seawater compared to freshwater, although the amount of As desorbed accounted for <0.2% of total As. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

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...

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

Science.gov (United States)

2012-01-01

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. PMID:22251433

Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

Science.gov (United States)

Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

2015-11-28

Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

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

OpenAIRE

Nemade, K. R.; Waghuley, S. A.

2014-01-01

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 a...

LA TEORÍA DEL CAOS... ESA NUBE TURBULENTA QUE DA QUÉ PENSAR

Directory of Open Access Journals (Sweden)

Rubén Antonio Sánchez Godoy

1999-01-01

Full Text Available Este texto plantea algunos de los problemas suscitados por la teoria del caos. Es decir, pretende mostrar algunas de las cuestiones que han surgido apartir 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 cientificos. En consecuencia, presentaremos a continuación un panorama de estos ploblemas 01 tanto que, por una parte, nos muesmi las posibilidades y los límites de dicha teona y , por otra, nos indican en qué sentido la teoría del caos puede dar qué pensar.

Synthesis and Characterization Of CaMgO2 Nanoparticles Photocatalyst For the Decolorization Of Orange G Dye

Directory of Open Access Journals (Sweden)

Atheel Alwash

2016-11-01

Full Text Available A series of heterogeneous basic catalysts of CaO, MgO and CaMgO2 at different calcination temperature were synthesized via solution combustion method. Different characterization techniques have been carried out to investigate the structure of the produced catalysts i.e. X-ray diffraction (XRD, particle size analyzer, morphology by atomic force microscope (AFM and reflection using UV-VIS diffuse reflectance spectra. The particles size analyzer revealed that the mixed oxide catalysts calcined at different calcination temperature possess smaller nano size particles compared to pure CaO. Moreover, the energy band gap was calculated based on the results of diffuse reflectance spectra. The energy band gap was reduced from 4.1 to 3.6 eV for the CaMgO2 catalyst calcined at 400 and 600 °C respectively compared to pure oxide catalysts. The higher decolorization efficiency was 100% after 60 min of photocatalytic reaction for CaMgO2 calcined at 600 °C compared to CaO and MgO with catalytic activity of 58% and 27% respectively.

Development of mechanical properties in a CaO added AZ31 magnesium alloy processed by equal-channel angular pressing

Energy Technology Data Exchange (ETDEWEB)

Bae, Seong-Hwan [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Metal Forming Technology R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Jung, Ki Ho; Shin, Young-Chul; Yoon, Duk Jae [Metal Forming Technology R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Kawasaki, Megumi, E-mail: megumi@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States)

2016-02-15

Processing through the application of equal-channel angular pressing (ECAP) is recognized as one of the attractive severe plastic deformation techniques where the processed bulk metals generally achieve ultrafine-grained microstructure leading to improved physical characteristics and mechanical properties. Magnesium has received much attention to date for its lightweight, high strength and excellent elasticity. Mg alloys with addition of CaO is reported to provide the successful casting procedure without usage of greenhouse gas, SF{sub 6}, whereas it is generally used for preventing the oxidation of Mg during casting. In the present investigation, a CaO added AZ31 (AZ31-CaO) magnesium alloy was processed by ECAP at elevated temepratures with a few steps of reduction which result in significant grain refinement to ~ 1.5 μm after 6 passes. Compression testing at room temperature demonstrated the AZ31-CaO alloy after ECAP showed enhanced yield strength more than the as-processed commercial AZ31 alloy while both alloys maintained ductility in spite of significant reduction in grain size. The improved strength in the AZ31-CaO alloy was attributed to the formation of fine Al{sub 2}Ca precipitates which experience breaking-up through ECAP and accelerate the microstructural refinement. Moreover, the preservation of ductility was attributed to the enhancement of strain hardening capability in the AZ31 alloy at room temperature. This study discusses the feasibility of using ECAP to improve both strength and ductility on magnesium alloys by applying the diagram describing the paradox of strength and ductility. - Highlights: • AZ31 and AZ31-CaO magnesium alloys were processed by ECAP up to 6 passes. • AZ31-CaO alloy after ECAP showed improved yield strength without losing ductility. • CaO in AZ31 forms fine Al{sub 2}Ca accelerating microstructural refinement during ECAP. • Feasibility of using ECAP was shown to improve both strength and ductility in Mg.

Development of mechanical properties in a CaO added AZ31 magnesium alloy processed by equal-channel angular pressing

International Nuclear Information System (INIS)

Bae, Seong-Hwan; Jung, Ki Ho; Shin, Young-Chul; Yoon, Duk Jae; Kawasaki, Megumi

2016-01-01

Processing through the application of equal-channel angular pressing (ECAP) is recognized as one of the attractive severe plastic deformation techniques where the processed bulk metals generally achieve ultrafine-grained microstructure leading to improved physical characteristics and mechanical properties. Magnesium has received much attention to date for its lightweight, high strength and excellent elasticity. Mg alloys with addition of CaO is reported to provide the successful casting procedure without usage of greenhouse gas, SF 6 , whereas it is generally used for preventing the oxidation of Mg during casting. In the present investigation, a CaO added AZ31 (AZ31-CaO) magnesium alloy was processed by ECAP at elevated temepratures with a few steps of reduction which result in significant grain refinement to ~ 1.5 μm after 6 passes. Compression testing at room temperature demonstrated the AZ31-CaO alloy after ECAP showed enhanced yield strength more than the as-processed commercial AZ31 alloy while both alloys maintained ductility in spite of significant reduction in grain size. The improved strength in the AZ31-CaO alloy was attributed to the formation of fine Al 2 Ca precipitates which experience breaking-up through ECAP and accelerate the microstructural refinement. Moreover, the preservation of ductility was attributed to the enhancement of strain hardening capability in the AZ31 alloy at room temperature. This study discusses the feasibility of using ECAP to improve both strength and ductility on magnesium alloys by applying the diagram describing the paradox of strength and ductility. - Highlights: • AZ31 and AZ31-CaO magnesium alloys were processed by ECAP up to 6 passes. • AZ31-CaO alloy after ECAP showed improved yield strength without losing ductility. • CaO in AZ31 forms fine Al 2 Ca accelerating microstructural refinement during ECAP. • Feasibility of using ECAP was shown to improve both strength and ductility in Mg.

Electronic, magnetic and optical properties of B, C, N and F doped MgO monolayer

Science.gov (United States)

Moghadam, A. Dashti; Maskane, P.; Esfandiari, S.

2018-06-01

MgO as one of the alkaline earth oxides has various applications in industry. In this work, we aim to investigate the electronic, optical and magnetic properties of MgO monolayers. Furthermore, monolayer structures with substituted B, N, C and F atoms instead of O atom are studied. These results indicate that MgO layer has possessed potential application in optoelectronic and spintronic nano-devices.

Positron annihilation 2D-ACAR study of semi-coherent Li nanoclusters in MgO(1 0 0) and MgO(1 1 0)

International Nuclear Information System (INIS)

Falub, C.V.; Mijnarends, P.E.; Eijt, S.W.H.; Huis, M.A. van; Veen, A. van; Schut, H.

2002-01-01

Depth selective positron annihilation two-dimensional angular correlation of annihilation radiation (2D-ACAR) is used to determine the electronic structure of Li nanoclusters formed by implantation of 10 16 cm -2 6 Li ions (with an energy of 30 keV) in MgO(1 0 0) and (1 1 0) crystals, and subsequently annealed at 950 K. The 2D-ACAR spectra of Li-implanted MgO obtained with 4 keV positrons reveal the semi-coherent ordering state of the embedded metallic Li nanoclusters. The results agree with ab initio Korringa-Kohn-Rostoker calculations

Positron annihilation 2D-ACAR study of semi-coherent Li nanoclusters in MgO(1 0 0) and MgO(1 1 0)

Energy Technology Data Exchange (ETDEWEB)

Falub, C.V. E-mail: c.falub@iri.tudelft.nl; Mijnarends, P.E.; Eijt, S.W.H.; Huis, M.A. van; Veen, A. van; Schut, H

2002-05-01

Depth selective positron annihilation two-dimensional angular correlation of annihilation radiation (2D-ACAR) is used to determine the electronic structure of Li nanoclusters formed by implantation of 10{sup 16} cm{sup -2} {sup 6}Li ions (with an energy of 30 keV) in MgO(1 0 0) and (1 1 0) crystals, and subsequently annealed at 950 K. The 2D-ACAR spectra of Li-implanted MgO obtained with 4 keV positrons reveal the semi-coherent ordering state of the embedded metallic Li nanoclusters. The results agree with ab initio Korringa-Kohn-Rostoker calculations.

Positron annihilation 2D-ACAR study of semi-coherent Li nanoclusters in MgO( 1 0 0 ) and MgO( 1 1 0 )

Science.gov (United States)

Falub, C. V.; Mijnarends, P. E.; Eijt, S. W. H.; van Huis, M. A.; van Veen, A.; Schut, H.

2002-05-01

Depth selective positron annihilation two-dimensional angular correlation of annihilation radiation (2D-ACAR) is used to determine the electronic structure of Li nanoclusters formed by implantation of 10 16 cm -26Li ions (with an energy of 30 keV) in MgO(1 0 0) and (1 1 0) crystals, and subsequently annealed at 950 K. The 2D-ACAR spectra of Li-implanted MgO obtained with 4 keV positrons reveal the semi-coherent ordering state of the embedded metallic Li nanoclusters. The results agree with ab initio Korringa-Kohn-Rostoker calculations.

Competitive Heterogeneous Nucleation Between Zr and MgO Particles in Commercial Purity Magnesium

Science.gov (United States)

Peng, G. S.; Wang, Y.; Fan, Z.

2018-04-01

Grain refining of commercial purity (CP) Mg by Zr addition with intensive melt shearing prior to solidification has been investigated. Experimental results showed that, when intensive melt shearing is imposed prior to solidification, the grain structure of CP Mg exhibits a complex changing pattern with increasing Zr addition. This complex behavior can be attributed to the change of nucleating particles in terms of their crystal structure, size, and number density with varied Zr additions. Naturally occurring MgO particles are found to be {100} faceted with a cubic morphology and 50 to 300 nm in size. Such MgO particles are usually populated densely in a liquid film (usually referred as oxide film) and can be effectively dispersed by intensive melt shearing. It has been confirmed that the dispersed MgO particles can act as nucleating substrates resulting in a significant grain refinement of CP Mg when no other more potent particles are present in the melt. However, Zr particles in the Mg-Zr alloys are more potent than MgO particles for nucleation of Mg due to their same crystal structure and similar lattice parameters with Mg. With the addition of Zr, Zr and the MgO particles co-exist in the melt. Grain refining efficiency is closely related to the competition for heterogeneous nucleation between Zr and the MgO particles. The final solidified microstructure is mainly determined by the interplay of three factors: nucleation potency (measured by lattice misfit), particle size, and particle number density.

Competitive Heterogeneous Nucleation Between Zr and MgO Particles in Commercial Purity Magnesium

Science.gov (United States)

Peng, G. S.; Wang, Y.; Fan, Z.

2018-06-01

Grain refining of commercial purity (CP) Mg by Zr addition with intensive melt shearing prior to solidification has been investigated. Experimental results showed that, when intensive melt shearing is imposed prior to solidification, the grain structure of CP Mg exhibits a complex changing pattern with increasing Zr addition. This complex behavior can be attributed to the change of nucleating particles in terms of their crystal structure, size, and number density with varied Zr additions. Naturally occurring MgO particles are found to be {100} faceted with a cubic morphology and 50 to 300 nm in size. Such MgO particles are usually populated densely in a liquid film (usually referred as oxide film) and can be effectively dispersed by intensive melt shearing. It has been confirmed that the dispersed MgO particles can act as nucleating substrates resulting in a significant grain refinement of CP Mg when no other more potent particles are present in the melt. However, Zr particles in the Mg-Zr alloys are more potent than MgO particles for nucleation of Mg due to their same crystal structure and similar lattice parameters with Mg. With the addition of Zr, Zr and the MgO particles co-exist in the melt. Grain refining efficiency is closely related to the competition for heterogeneous nucleation between Zr and the MgO particles. The final solidified microstructure is mainly determined by the interplay of three factors: nucleation potency (measured by lattice misfit), particle size, and particle number density.

Biodiesel production from palm oil using hydrated lime-derived CaO as a low-cost basic heterogeneous catalyst

International Nuclear Information System (INIS)

Roschat, Wuttichai; Siritanon, Theeranun; Yoosuk, Boonyawan; Promarak, Vinich

2016-01-01

Graphical abstract: Hydrated lime-derived CaO can be utilized as high efficient heterogeneous solid catalyst for transesterification of palm oil to biodiesel product. - Highlights: • CaO with high surface area and pore volume was successfully prepared from hydrated lime using a simple method. • Hydrated lime-derived CaO were used as a catalyst in transesterification of palm oil to biodiesel. • Over 97% FAME yield was achieved from transesterification of palm oil in 2 h. • This CaO has high potential for applications as green and low-cost catalyst. - Abstract: In this study, hydrated lime-derived calcium oxide (CaO) was used as a catalyst for the transesterification of palm oil. The catalysts were characterized by TG-DTA, XRD, XRF, FT-IR, SEM, Hammett indicator method, TPD-CO_2 and BET by N_2 adsorption. Under the optimal conditions at catalyst loading of 6 wt.%, methanol/oil molar ratio of 15:1, reaction temperature 65 °C, and stirring rate of 200 rpm; 97% yield of biodiesel could be achieved in 2 h. Effects of water amount were investigated and the catalyst could tolerate high water content of 5 wt.%. The kinetic of the reaction followed pseudo-first order with the activation energy (Ea) of 121.12 kJ/mol and frequency factor (A) of 1.203 × 10"1"7 min"−"1. After treatments, high quality biodiesel was obtained which indicated that the very cheap hydrated lime-derived CaO showed excellent catalytic activity and high potential for applications in biodiesel production.

Highly active CaO for the transesterification to biodiesel production ...

African Journals Online (AJOL)

TMCS) for transesterification of rapeseed oil and methanol to biodiesel production was studied. It was found that the fatty acid methyl esters (FAME) yield of the modified CaO was greatly enhanced from 85.4% to 94.6% under 65 oC with 15:1 ...

Insulator at the ultrathin limit: MgO on Ag(001).

Science.gov (United States)

Schintke, S; Messerli, S; Pivetta, M; Patthey, F; Libioulle, L; Stengel, M; De Vita, A; Schneider, W D

2001-12-31

The electronic structure and morphology of ultrathin MgO films epitaxially grown on Ag(001) were investigated using low-temperature scanning tunneling spectroscopy and scanning tunneling microscopy. Layer-resolved differential conductance (dI/dU) measurements reveal that, even at a film thickness of three monolayers, a band gap of about 6 eV is formed corresponding to that of the MgO(001) single-crystal surface. This finding is confirmed by layer-resolved calculations of the local density of states based on density functional theory.

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.

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

Science.gov (United States)

Kumar, Danith; Yadav, L. S. Reddy; Lingaraju, K.; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.; Naika, H. Raja; Chikkahanumantharayappa, Nagaraju, G.

2015-06-01

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm-1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV -Vis spectrum was found to be in the range 5.40-5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

Science.gov (United States)

Vilayurganapathy, S.; Devaraj, A.; Colby, R.; Pandey, A.; Varga, T.; Shutthanandan, V.; Manandhar, S.; El-Khoury, P. Z.; Kayani, Asghar; Hess, W. P.; Thevuthasan, S.

2013-03-01

Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. 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 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized 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 by 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.

Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

International Nuclear Information System (INIS)

Vilayurganapathy, S; Devaraj, A; Colby, R; Pandey, A; Varga, T; Shutthanandan, V; Manandhar, S; Thevuthasan, S; El-Khoury, P Z; Hess, W P; Kayani, Asghar

2013-01-01

Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. 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 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized 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 by 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. (paper)

Effect of CaO on Hot Workability and Microstructure of Mg-9.5Zn-2Y Alloy

Science.gov (United States)

Kwak, Tae-yang; Kim, Daeguen; Yang, Jaehack; Yoon, Young-ok; Kim, Shae K.; Lim, Hyunkyu; Kim, Woo Jin

Mg-Zn-Y system alloys have been a great interest because Mg-Zn-Y alloys with I-phase exhibited high ductility at room and elevated temperatures. According to our preliminary experiments, the addition of CaO improved strength, but the process window became narrow. Therefore, the aim of current work was to find optimum extrusion conditions for CaO added Mg-Zn-Y alloys by processing maps. The 0.3 wt.% of CaO added Mg-9.5Zn-2Y (Mg95.6Zn3.8Y0.6) alloy was prepared by casting into steel mold and homogenizing. Hot compression test were performed in the Gleeble machine at temperature range of 250-400 °C with various strain rates. The alloys were extruded with a reduction ratio of 20:1. To analyze the microstructure and texture, optical micrograph, scanning electron microscope and electron backscattered diffraction were used. Moreover, we investigated the effects of metallic Ca addition in this alloy to compare with the addition of CaO.

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.

Analýza marketingovej stratégie firmy Jamex s.r.o. na slovenskom trhu

OpenAIRE

Jancová, Andrea

2015-01-01

This bachelor thesis deals with the marketing strategy of Slovak company JAMEX s.r.o., which is a seller and producer of metallurgical material and reinforcing steel. The aim of the thesis is to analyse current marketing strategy of the company, create situational analysis, SWOT analysis and describe its marketing mix. The obtained data helps to suggest improvements and decide what measures should be taken in order to strengthen the position on the market. Furthermore, the last part of the th...

Saving on natural resources with SRO - desalination of industrial waste water for reuse at ESKOM Tutuka (two years operating experience)

Energy Technology Data Exchange (ETDEWEB)

Walt, Mike van der; Wessels, A.

2001-07-01

Natural resources are protected and saved with the new spiral reverse osmosis (SRO) plant at the Eskom Tutuka power station in the Mpumalanga province of South Africa. 7,000 m{sup 3}/day of saline underground mine water blended with 5,400 m{sup 3}/day of cooling water blowdown is pretreated and desalinated before the product water is returned to the cooling water circuit. Weir Envig designed, constructed, installed and commissioned the plant in phases between August 1998 and April 1999 with innovative use of existing infrastructure and phased removal of the live, ageing electrodialysis reversal plant. The plant performance during two years of operation is presented, which demonstrates that good pretreatment and cleaning system design allows SRO to produce consistent high-quality water from this difficult and varying feed. The result is a coal mine with no effluent problems, a new source of water for the power station and a treatment plant, which produces significantly better condenser cooling water and maintain zero liquid discharge. (orig.)

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

International Nuclear Information System (INIS)

Park, J.H.; Kassner, T.F.

1996-01-01

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 ∼7-8 μm 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 10 Ω-cm 2 at 300 degrees C and 400 h, and 0.9 x 10 10 Ω-cm 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

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.

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

Energy Technology Data Exchange (ETDEWEB)

Kumar, Danith; Chikkahanumantharayappa [Dept. of Physics, Vivekananda First grade College, Bangalore - 560055 (India); Yadav, L. S. Reddy; Nagaraju, G., E-mail: nagarajugn@rediffmail.com [Dept of Chemistry, Siddaganga Institute of Technology, Tumkur, Karnataka-572103 (India); Lingaraju, K.; Naika, H. Raja [Dept. of Environmental Science, Tumkur University, Tumkur, Karnataka-572103 (India); Manjunath, K. [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Karnataka-562112 (India); Suresh, D. [Dept. of Chemistry, Tumkur University, Tumkur, Karnataka-572103 (India); Prasad, Daruka [Dept. of Physics, BMS Institute of Technology, Bangalore-560064 (India); Nagabhushana, H. [CNR Rao Center for Advanced Materials, Tumkur University, Tumkur, Karnataka-572103 (India); Sharma, S. C. [Chattisgarh Swami Vivekananda Technological University, Bhilai, Chattisgarh-490009 (India)

2015-06-24

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm{sup −1} indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

International Nuclear Information System (INIS)

Kumar, Danith; Chikkahanumantharayappa; Yadav, L. S. Reddy; Nagaraju, G.; Lingaraju, K.; Naika, H. Raja; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.

2015-01-01

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm −1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation

Solar Thermochemical Energy Storage Through Carbonation Cycles of SrCO3/SrO Supported on SrZrO3.

Science.gov (United States)

Rhodes, Nathan R; Barde, Amey; Randhir, Kelvin; Li, Like; Hahn, David W; Mei, Renwei; Klausner, James F; AuYeung, Nick

2015-11-01

Solar thermochemical energy storage has enormous potential for enabling cost-effective concentrated solar power (CSP). A thermochemical storage system based on a SrO/SrCO3 carbonation cycle offers the ability to store and release high temperature (≈1200 °C) heat. The energy density of SrCO3/SrO systems supported by zirconia-based sintering inhibitors was investigated for 15 cycles of exothermic carbonation at 1150 °C followed by decomposition at 1235 °C. A sample with 40 wt % of SrO supported by yttria-stabilized zirconia (YSZ) shows good energy storage stability at 1450 MJ m(-3) over fifteen cycles at the same cycling temperatures. After further testing over 45 cycles, a decrease in energy storage capacity to 1260 MJ m(-3) is observed during the final cycle. The decrease is due to slowing carbonation kinetics, and the original value of energy density may be obtained by lengthening the carbonation steps. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of CaO on the compaction and sintering by plasma of Powder-metallurgical iron

Science.gov (United States)

Ariza Suarez, H. G.; Sarmiento Santos, A.; Ortiz Otálora, C. A.

2017-12-01

This work the effect of the addition of Calcium Oxide (CaO) in the compaction and sintering of powder metallurgical iron Ancoor Steel 1000® is studied. Iron samples were made with proportions of: 0.5%, 1%, 1.5% and 2% by weight of CaO. The samples were sintered in a luminescent discharge furnace, in an atmosphere of H2+Ar at a temperature of 1150°C. XRD analysis was used to determine the formation of compounds, this analysis evidenced the formation of: hematite and magnetite, which were found both on the surface and in the volume. A characterization of the ability to protect against corrosive effects was carried out using the EIS electrochemical impedance spectroscopy method on the samples, in a solution of 1000ppm of chloride, with this procedure it was found that at a concentration of 0.5% and 1% CaO, the electrochemical impedance value is increased with values of 11.7MΩ, 2.2MΩ respectively.

Trap characterization by photo-transferred thermoluminescence in MgO nanoparticles

Science.gov (United States)

Isik, M.; Gasanly, N. M.

2018-05-01

Shallow trapping centers in MgO nanoparticles were characterized using photo-transferred thermoluminescence (TL) measurements. Experiments were carried out in low temperature range of 10-280 K with constant heating rate. Shallow traps were filled with charge carriers firstly by irradiating the sample at room temperature using S90/Y90 source and then illuminating at 10 K using blue LED. TL glow curve exhibited one peak around 150 K. Curve fitting analyses showed that this peak is composed of two individual peaks with maximum temperatures of 149.0 and 155.3 K. The activation energies of corresponding trapping centers were revealed as 0.70 and 0.91 eV. The dominant mechanism for TL process was found as second order kinetics which represent that fast retrapping is effective transitions taking place within the band gap. Structural characterization of MgO nanoparticles were investigated using x-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. Analyses of experimental observations indicated that MgO nanoparticles show good crystallinity with particle size in nanometer scale.

Biodiesel production from transesterification of palm oil with methanol over CaO supported on bimodal meso-macroporous silica catalyst.

Science.gov (United States)

Witoon, Thongthai; Bumrungsalee, Sittisut; Vathavanichkul, Peerawut; Palitsakun, Supaphorn; Saisriyoot, Maythee; Faungnawakij, Kajornsak

2014-03-01

Calcium oxide-loaded porous materials have shown promise as catalysts in transesterification. However, the slow diffusion of bulky triglycerides through the pores limited the activity of calcium oxide (CaO). In this work, bimodal meso-macroporous silica was used as a support to enhance the accessibility of the CaO dispersed inside the pores. Unimodal porous silica having the identical mesopore diameter was employed for the purpose of comparison. Effects of CaO content and catalyst pellet size on the yield of fatty acid methyl esters (FAME) were investigated. The basic strength was found to increase with increasing the CaO content. The CaO-loaded bimodal porous silica catalyst with the pellet size of 325μm achieved a high %FAME of 94.15 in the first cycle, and retained an excellent %FAME of 88.87 after five consecutive cycles. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

Technical Report on the Impact of MgO on Defense Waste Processing Facility

International Nuclear Information System (INIS)

Schultz, R.L.

2000-01-01

The purpose of this study was to determine the effect(s) of removing MgO from DWPF frits to assess the impact on liquidus temperature and the durability of the glass product. Removal of MgO from the frit was hypothesized to lead to a decrease in liquidus temperature and thereby allow increased waste loading

Effect of various additives on microstructure, mechanical properties, and in vitro bioactivity of sodium oxide-calcium oxide-silica-phosphorus pentoxide glass-ceramics.

Science.gov (United States)

Li, H C; Wang, D G; Hu, J H; Chen, C Z

2013-09-01

The partial substitution of MgO, TiO2, or CaF2 for CaO in the Na2O-CaO-SiO2-P2O5 (45S5) system was conducted by the sol-gel method and a comparative study on structural, mechanical properties, and bioactivity of the glasses was reported. Based on thermogravimetric and differential thermal analysis, the gels were sintered with a suitable heat treatment procedure. The glass-ceramic properties were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and so on, and the bioactivity of the glass-ceramic was evaluated by in vitro assays in simulated body fluid (SBF). Results indicate that with the partial substitution of MgO, TiO2, CaF2 for CaO in glass composition, the mechanical properties of the glass-ceramics have been significantly improved. Furthermore, CaF2 promotes glass crystallization and the crystallization does not inhibit the glass-ceramic bioactivity. All samples possess bioactivity; however, the bioactivity of these glass-ceramics is quite different. Compared with 45S5, the introduction of MgO decreases the ability of apatite induction. The addition of TiO2 does not significantly improve the bioactivity, and the replacement of CaO by CaF2 shows a higher bioactivity. Copyright © 2013 Elsevier Inc. All rights reserved.

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.

Synthesis, characterization, and catalytic property of nanosized MgO flakes with different shapes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yongfen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Hebei Vocational and Technical College of Building Materials, Qinhuangdao 066004 (China); Ma, Mingzhen, E-mail: mz550509@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, Xinyu; Wang, Baoan; Liu, Riping [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

2014-03-25

Highlights: • MgO nanoflakes with different morphologies were synthesized by a simple low-temperature hydrothermal process. • EDTA and KCl additives have a great effect on the morphology of the products. • Quasi-circular MgO nanoflakes exhibited higher catalytic activity on the thermal decomposition of ammonium perchlorate. -- Abstract: The nanostructures of quasi-circular and hexagonal magnesium oxide (MgO) flakes were successfully prepared by a simple low-temperature hydrothermal reaction. The morphologies were confirmed by field-emission scanning electron microscopy and transmission electron microscopy. Powder X-ray diffraction analysis showed that the nanostructures consisted of cubic-phase MgO. When ethylenediaminetetraacetic acid and potassium chloride were added to the reaction system, the shapes of the synthesized products were found to transform from hexagonal to quasi-circular nanoflakes for different time scales. Fourier-transform infrared spectroscopy indicated numerous hydroxyl radicals on the surface. Quasi-circular magnesia nanoflakes exhibited relatively high catalyst activity for the thermal decomposition of ammonium perchlorate. The mechanism of enhanced catalyst activity was also discussed.

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.

Quicklime (CaO) Stabilization of fine-grained marine sediments in low temperature areas

DEFF Research Database (Denmark)

Skels, Peteris; Ingeman-Nielsen, Thomas; Jørgensen, Anders Stuhr

2011-01-01

This study presents laboratory testing on quicklime (CaO) stabilization of fine-grained marine sediments in low temperature areas. The soil was sampled on the Fossil Plain in Kangerlussuaq, Greenland, and analyzed in the laboratory at Technical University of Denmark (DTU). The optimum CaO content...... curing temperatures, comparing stabilization effectiveness between low and normal soil temperature conditions....... in a soil-CaO mixture was determined using a number of laboratory methods, such as pH test, consistency limit analysis, degree of compaction, and short term California Bearing Ratio (CBR) values. The study also numerically demonstrates a long term strength development of the soil-CaO mixture at 1°C and 10°C...

Palygorskite Hybridized Carbon Nanocomposite as a High ...

African Journals Online (AJOL)

NICO

Pd nanoparticles were deposited on the hybrid support as an electrocatalyst for formic acid oxida- tion. .... synthetic procedure using conventional borohydride reduction .... as Al2O3, CaO and MgO, which may exist in both the tetrahedral.

Fashion marketing se zaměřením na mikropodnik - Krispol fashion s.r.o.

OpenAIRE

Berný, Ondřej

2017-01-01

Bachelors thesis is focused on fashion marketing and its application on company Krispol fashion s.r.o., which engaged in manufacturing of handmade bow-ties. The objective of the bachelors thesis is a survey of how the companys marketing activities are percepted by the current customers and how these customers participate in such activities. The main marketing activities are participation in fashion markets and presenting on companys Facebook page. The thesis consists of a theoretical and a pr...

Effect of sulfated CaO on NO reduction by NH{sub 3} in the presence of excess oxygen

Energy Technology Data Exchange (ETDEWEB)

Tianjin Li; Yuqun Zhuo; Yufeng Zhao; Changhe Chen; Xuchang Xu [Tsinghua University, Beijing (China). Key Laboratory for Thermal Science and Power Engineering of Ministry of Education

2009-04-15

The effect of sulfated CaO on NO reduction by NH{sub 3} in the presence of excess oxygen was investigated to evaluate the potential of simultaneous SO{sub 2} and NO removal at the temperature range of 700-850{sup o}C. The physical and chemical properties of the CaO sulfation products were analyzed to investigate the NO reduction mechanism. Experimental results showed that sulfated CaO had a catalytic effect on NO reduction by NH{sub 3} in the presence of excess O{sub 2} after the sulfation reaction entered the transition control stage. With the increase of CaO sulfation extent in this stage, the activity for NO reduction first increased and then decreased, and the selectivity of NH{sub 3} for NO reduction to N{sub 2} increased. The byproduct (NO{sub 2} and N{sub 2}O) formation during NO reduction experiments was negligible. X-ray photoelectron spectroscopy (XPS) analysis showed that neither CaSO{sub 3} nor CaS was detected, indicating that the catalytic activity of NO reduction by NH{sub 3} in the presence of excess O{sub 2} over sulfated CaO was originated from the CaSO{sub 4} product. These results revealed that simultaneous SO{sub 2} and NOx control by injecting NH{sub 3} into the dry flue gas desulfurization process for NO reduction might be achieved. 38 refs., 6 figs., 1 tab.

gold mineralization in Masjeddaghi area, east of Jolfa, NW Iran

Directory of Open Access Journals (Sweden)

Ali Imamalipour

2010-11-01

Full Text Available Two types of mineralization including porphyry copper and epithermal gold mineralization have occurred in relation with an intermediate volcano-plutonic complex in Masjeddaghi area. Different alterations including silica, advanced argillic, intermediate argillic and propylitic have been distinguished in relation with epithermal mineralization, which have a zonal pattern. Elemental mass gains and losses during alterations were calculated using Zr as an immobile monitor. Silica zone has enriched in SiO2 and relatively in Al2O3 and K2O, and has depleted in Na2O, MgO and CaO. Ba, Sr, Pb, Rb and Cu elements have also enriched. The advanced argillic zone shows enrichment in SO3, Al2O3, SiO2, K2O, MgO and L.O.I; and depletion in Fe2O3, CaO, Na2O, MnO and MgO. Barium, Cu, Sr and Zn have depleted in this zone. Propylitic zone has enriched in MgO, CaO, L.O.I and SiO2, and has depleted in Na2O and K2O. Geochemical and mineralogical evidences indicate that the hydrothermal leaching of mafic minerals in parent rocks and formation of quartz, kaolinite, sericite and alunite assemblage in advanced argillic zone; and chlorite, epidote and calcite assemblage in propylitic zone is responsible for the above mentioned chemical variations. It is likely that the gains and losses of elements have been controlled by agents such as water/rock ratios, temperature changes and chemistry of hydrothermal solutions. The CIA and MIA indicators in the altered rocks indicate the intensity of alteration in silica and advanced argillic zones in comparison with propylitic zone.

Codeboek DUCADAM dataset: een statistisch bestand van de FNV cao-databank

NARCIS (Netherlands)

Schreuder, K.; Tijdens, K.

2004-01-01

The ‘FNV cao-databank’ is a digital database that stores all collective labour agreements negotiated by FNV trade unions in the Netherlands since 1995. Every agreement has been coded with respect to 650 different characteristics. The DUCADAM dataset is both a scientific translation of this database

Multi-particle assembled porous nanostructured MgO: its application in fluoride removal

International Nuclear Information System (INIS)

Gangaiah, Vijayakumar; Chandrappa, Gujjarahalli Thimanna; Siddaramanna, Ashoka

2014-01-01

In this article, a simple and economical route based on ethylene glycol mediated process was developed to synthesize one-dimensional (1D) multiparticle assembled nanostructured MgO using magnesium acetate and urea as reactants. Porous multiparticle chain-like MgO has been synthesized by the calcination of a solvothermally derived single nanostructured precursor. The prepared products were characterized by an x-ray diffraction (XRD) pattern, thermogravimetry, scanning/transmission electron microscopy (SEM/TEM) and N 2 adsorption (BET). As a proof of concept, the porous multiparticle chain-like MgO has been applied in a water treatment for isolated and rural communities, and it has exhibited an excellent adsorption capability to remove fluoride in waste water. In addition, this method could be generalized to prepare other 1D nanostructures with great potential for various attractive applications. (paper)

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.

[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.

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

2014AbstractThree different compositions of MgO compounds were investigated for use in oxygen transport membranes. Porous MgO supports were extruded using different kind (size, morphology and chemistry) of pore formers: A flaky graphite, a spherical graphite and ideal spheres of PMMA. The influence...... 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...

Solid solubility of MgO in the calcium silicates of portland clinker. The effect of CaF2

Directory of Open Access Journals (Sweden)

Puertas, F.

1992-03-01

Full Text Available The solid solubility of MgO in the calcium silicates of portland clinker has been determined by XRD and XDS. The influence that the presence of CaF2 has on said solubility has also been verified. The solid solution limit of MgO in C3S at 1275 ºC lies at about 1.0% wt, where the triclinic form II stabilizes. The presence of CaF2 does not alter the maximum value of the MgO solubilized in that silicate, although there does take place the stabilization of the triclinic polymorph II at lower MgO contents (between 0.3 - 0.6% wt. The maximum amount of solubilized MgO in βC2 at 1.050 ºC lies around 0.5% wt. This value does not change by the presence of CaF2.Se ha determinado por DRX y EDX la solubilidad sólida del MgO en los silicatos cálcicos del clínker portland. Se ha comprobado, así mismo la influencia que sobre dicha solubilidad tiene la presencia de CaF2. El límite de disolución sólida del MgO en el C3S a 1.275º C se sitúa alrededor del 1,0% en peso, estabilizándose la forma triclínica II. La presencia de CaF2 no altera el valor máximo de MgO solubilizado en este silicato, aunque si se produce la estabilización del polimorfo triclínico II a contenidos menores de MgO (entre 0,3 – 0,6% en peso. La cantidad máxima de MgO solubilizado en e/ βC2S a 1.050 ºC se sitúa en torno al 0,5% en peso. Este valor no se ve modificado por la presencia de CaF2.

Aldol Condensation of Citral with Acetone on Basic Solid Catalysts

Directory of Open Access Journals (Sweden)

NODA C.

1998-01-01

Full Text Available The catalytic performance of solids with basic properties, such as CaO, MgO and hydrotalcites, was evaluated in the aldol condensation of citral and acetone, the first step in the synthesis of ionones from citral. The best results were obtained with CaO and hydrotalcite with high conversions (98% and selectivities (close to 70% for the main product observed for both of the catalyst. Such pseudoionone yields were greater than those reported in the literature for the homogeneous reaction.

Activated carbon supported CaO for conversion of palm oil to ...

African Journals Online (AJOL)

In this study, activated carbon supported CaO catalyst was used for the transesterification reaction of palm oil. The catalyst was prepared according to the conventional incipient witness impregnation method. Kinetic experiment was performed in a batch reactor in the presence of heterogeneous catalyst for a wide range of ...

Roles of ethylene glycol solvent and polymers in preparing uniformly distributed MgO nanoparticles

Directory of Open Access Journals (Sweden)

Chunxi Hai

2017-06-01

Full Text Available This study focus on specifying the roles of solvent ethylene glycol (EG and polymers for synthesis of uniformly distributed magnesium oxide (MgO nanoparticles with average crystallite size of around 50 nm through a modified polyol method. Based on different characterization results, it was concluded that, Mg2+ ions was precipitated by the −OH and CO32− ions decomposed from urea in ethylene glycol (EG medium (CO(NH22 → NH3 + HNCO, HNCO + H2O → NH3 + CO2, thus forming well crystallized Mg5(CO34(OH2 (H2O4 precursor which could be converted to MgO by calcination. Surface protectors PEG and PVP have no obvious influences on cyrtsal structure, morphology and size uniformity of as-prepared precursors and target MgO nanoparticles. In comparison with polymers PEG and PVP, solvent EG plays an important role in controlling the morphology and diameter uniformity of MgO nanoparticles.

Iodine Plasma (Electric Propulsion) Interaction with Spacecraft Materials

Science.gov (United States)

2016-12-28

Teflon (AGT5, Ag-FEP) Thermal control surface (radiator) Spacecraft Exposure Soda-lime glass (74% SiO2 , 13% Na2O, 8% CaO, 4% MgO, 1% other oxide... Glass Solar panel cover Spacecraft Exposure Buna-N (acrylonitrile butadiene rubber) Seals Iodine Feed System Carbon fiber composite (epoxy resin...Fe Propellant isolator Spacecraft Exposure Lanthanum Hexaboride, LaB6 Cathode emitter Inside Cathode Yes MACOR (46% SiO2 , 17% MgO, 16% Al2O3, 10

Marketingový mix společnosti DOG production s.r.o.

OpenAIRE

Bartáková, Veronika

2012-01-01

Předmětem bakalářské práce „Marketingový mix společnosti DOG production“ je rozbor jednotlivých nástrojů marketingového mixu a návrh vhodného řešení této problematiky. Práce se skládá ze tří hlavních částí. První teoretická část rozebírá základní termíny marketingu. Druhá praktická se zaměřuje na společnost DOG production s.r.o., její poslání, rozbor jednotlivých prvků marketingového mixu, specifikaci trhu, na kterém společnost operuje a definuje zahraniční trh, kam se plánuje uchýlit. Východ...

THE THERMODYNAMIC PROPERTIES OF MELTS OF DOUBLE SYSTEM MgO – Al2O3, MgO – SiO2, MgO – CaF2, Al2O3 – SiO2, Al2O3 – CaF2, SiO2 – CaF2

Directory of Open Access Journals (Sweden)

В. Судавцова

2012-04-01

Full Text Available Methodology of prognostication of thermodynamics properties of melts is presented from the coordinatesof liquidus of diagram of the state in area of equilibria a hard component is solution, on which energies ofmixing of Gibbs are expected in the double border systems of MgO – Al2O3, MgO – SiO2, MgO – CaF2,Al2O3 – SiO2, Al2O3 - CaF2, SiO2 - CaF2. For the areas of equilibrium there is quasibinary connection(MgAl2O4, Mg2SiO4, Al6Si2O13 – a grout at calculations was used equalization of Hauffe-Wagner. Theobtained data comport with literary

Defect induced ferromagnetism in MgO nanoparticles studied by optical and positron annihilation spectroscopy

Science.gov (United States)

Kumar, Nitesh; Sanyal, D.; Sundaresan, A.

2009-08-01

Positron annihilation spectroscopy has been used to explore the nature of defects and to estimate the defect concentrations in ferromagnetic MgO nanoparticles. Our experimental results show that Mg vacancies or Mg vacancy concentration are present approximately at the concentration of 3.4 × 10 16 cm -3 in the nano-crystalline MgO which is twice the value that obtained for bulk sample. This is in correlation with the decrease of the intensity of blue luminescence and the saturation magnetic moment with increasing particle size. These results clearly demonstrate that the origin of magnetic moment and thus the ferromagnetism in MgO nanoparticles is due to Mg related vacancies at the surface of the particles.

Concrete with steel furnace slag and fractionated reclaimed asphalt pavement.

Science.gov (United States)

2014-09-01

Steel furnace slag (SFS) is an industrial by-product material that can contain free calcium oxide (CaO) and free magnesium oxide (MgO), both : of which can cause significant expansion when hydrated. SFS aggregates are therefore not commonly used in c...

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.

Interlayer exchange coupling, dipolar coupling and magnetoresistance in Fe/MgO/Fe trilayers with a subnanometer MgO barrier

Energy Technology Data Exchange (ETDEWEB)

Kozioł-Rachwał, A. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Skowroński, W.; Frankowski, M. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Chęciński, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ziętek, S.; Rzeszut, P. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ślęzak, M.; Matlak, K.; Ślęzak, T. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Stobiecki, T. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Korecki, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)

2017-02-15

Fe/MgO/Fe trilayers with a subnanometer MgO tunnel barrier were grown by molecular beam epitaxy. Longitudinal magnetooptic Kerr effect measurements confirmed the existence of the antiferromagnetic interlayer exchange coupling (IEC) between the Fe layers for 2 ÅMgO}<6 Å. The coupling was enhanced for the trilayer grown on a homoepitaxial MgO buffer layer, and its IEC constant was estimated to be −3.3 erg/cm{sup 2} at a MgO thickness of 2.7 Å. After magnetic characterization, the sample was patterned into circular-shaped pillars with diameters ranging from 200 nm to 520 nm. We showed that the dipolar coupling that appeared after the nanofabrication process modified the effective coupling between layers, and we determined dependence of the dipolar coupling on the pillar diameter. Finally, magnetoresistance (MR) was measured as a function of MgO thickness (d{sub MgO}), and a non-zero MR was found for the MgO as thin as 3.4 Å. Extrapolation of the MR (d{sub MgO}) dependence to MR=0 allowed us to determine the length of the pinholes in our sample, which was estimated to be (3.2±0.5) Å. - Highlights: • Strong antiferromagnetic (AFM) interlayer exchange coupling (IEC) between Fe layers in Fe/MgO/Fe. • After nanofabrication the effective AFM IEC is enhanced due to the dipolar coupling. • The dipolar coupling that appeared after the nanofabrication process modified the effective coupling between layers. • Non-zero magnetoresistance values registered for the Fe/MgO/Fe trilayers with the MgO spacers as thin as 3.4 Å.

Effect of Cs and Li atom adsorption on MgO: Secondary emission and work function

International Nuclear Information System (INIS)

Bagraev, N.T.; Borisov, V.L.

1980-01-01

Adsorption of Cs and Li atoms on the surface of single crystal magnesium oxide films has been investigated using Auger, LEED and contact difference techniques. A decreased work function for a single crystal MgO film grown on the Mo (100) face was observed to be accompanied by an increased secondary electron emission yield shown to be due to a larger escape depth for secondary electrons. LEED showed well ordered layers of adsorbed Cs on the MgO film surface. A model to explain the behaviour of Cs atoms on the film surface is proposed. It is shown that the stability of the Cs coating is not dependent on a prolonged bombardment of the film by incident electron beams of high current density. Depositing and implanting of thin single crystal MgO films with Li were found to result in an increased secondary electron emission yield, with Li adsorption on the MgO film surface being disordered. (orig.)

Komparace dvou systémů prodeje společnosti adidas ČR s.r.o.

OpenAIRE

Dolejší, Kateřina

2011-01-01

The primary aim of the diploma thesis is to evaluate the pros and cons of two types of sales systems at adidas ČR, i.e. the franchise stores and own adidas Concept Stores. On the basis of an analysis of the compared sales systems, the thesis suggests improvement measures for both systems and provides recommendations for similar types of retail formats. The thesis should make clear the issue of running a franchised business as compared to running an own retail shop of adidas ČR s.r.o. by intro...

Sound post production in advertising and in the film, case study of Studio Beep s.r.o.

OpenAIRE

Struhařová, Michaela

2012-01-01

Main topic of this thesis is description of sound post production in advertising and in the film film industry and making case study of company Studio Beep s.r.o. First aim of this thesis is describe as clearly as possible the theory of sound and sound post production in advertising and in film industry and also show specifics accompanying production of sound in each discipline. The theoretical part contains basic overview about history of sound, sound dramaturgy and about general principles ...

Role of Mg{sub x}Ca{sub 1−x}CO{sub 3} on the physical–chemical properties and cyclic CO{sub 2} capture performance of dolomite by two-step calcination

Energy Technology Data Exchange (ETDEWEB)

Wang, Ke; Han, Dongtai, E-mail: handongtai@cumt.edu.cn; Zhao, Pengfei, E-mail: zhaopfcumt@163.com; Hu, Xiumeng; Yin, Zeguang; Wu, Di

2015-08-20

Highlights: • Two-step calcination treated dolomite sorbent was prepared and characterized. • An intermediate phase (Mg{sub x}Ca{sub 1−x}CO{sub 3}) was observed by TG and XRD results. • Mg-calcite hindered the de-mixing of Ca and Mg. • Smaller grains, larger specific surface area and pore volume were obtained. • This favorable structure resulted in a high and stable CO{sub 2} capture performance. - Abstract: Two-step calcination (CO{sub 2} and N{sub 2} atmospheres) was used to modify the microstructure of natural dolomite for high-temperature CO{sub 2} capture. Two other one-step calcinations (CO{sub 2} or N{sub 2} atmosphere) were provided for comparison. Different morphological characterizations (thermal decomposition, phase composition, morphology, and nitrogen adsorption) were performed, followed by an analysis of 30 carbonation/calcination cycles in a fixed bed reactor. During primary calcination in a CO{sub 2} atmosphere, an intermediate phase (Mg{sub x}Ca{sub 1−x}CO{sub 3}) was observed by TG and XRD results, which hindered the de-mixing of CaO and MgO in the secondary calcination in a N{sub 2} atmosphere. Therefore, two-step calcination produced smaller grains (CaO: 45.2 nm; MgO: 32.6 nm), larger specific surface area (21.08 m{sup 2}/g) and pore volume (0.082 cm{sup 3}/g) and uniform distribution of CaO and MgO, which resulted in a higher and more stable uptake of CO{sub 2} compared to the results from one-step calcinations.

The Effect of Varying Speed Release of Nutrients from Fertilizers on Growth-production Process of Turf

Directory of Open Access Journals (Sweden)

Peter Hric

2016-01-01

Full Text Available The aim of this experiment was to compare the influence of fertilizers with different speed of nutrients release on growth–production indicators of turf under non–irrigated conditions. The experiment was carried in warm and dry conditions in area Nitra (Slovak Republic. In the experiment were followed 5 treatments (1. without fertilization, 2. Nitre with dolomite, Superphosphate, Potassium salt, 3. Turf fertilizer Travcerit®, 4. Slow release fertilizer SRF NPK 14–5–14 (+ 4CaO + 4MgO + 7S, 5. Controlled release fertilizer Duslocote® NPK (S 13–9–18 (+6S. The highest gain of height reached variant fertilized by fertilizer SRF NPK 14–5–14 (+ 4CaO + 4MgO + 7S. Comparison of the individual treatments for the whole period showed significantly lower average daily gains of height on control treatment compared to fertilizing treatments Nitre with dolomite, Superphosphate, Potassium salt, SRF NPK 14–5–14 (+ 4CaO + 4MgO + 7S and Duslocote® NPK (S 13–9–18 (+6S. During the reported period the highest gain of weight reached treatment by application fertilizer Duslocote® NPK (S 13– 9–18 (+ 6S. Comparison of the individual treatments for the whole period, were found significantly lower average daily production of phytomass on control treatment in comparison with fertilization turfs by Travcerit® and Duslocote® NPK (S 13–9–18 (+6S.

Reaction kinetics of dolomite rim growth

Science.gov (United States)

Helpa, V.; Rybacki, E.; Abart, R.; Morales, L. F. G.; Rhede, D.; Jeřábek, P.; Dresen, G.

2014-04-01

Reaction rims of dolomite (CaMg[CO3]2) were produced by solid-state reactions at the contacts of oriented calcite (CaCO3) and magnesite (MgCO3) single crystals at 400 MPa pressure, 750-850 °C temperature, and 3-146 h annealing time to determine the reaction kinetics. The dolomite reaction rims show two different microstructural domains. Elongated palisades of dolomite grew perpendicular into the MgCO3 interface with length ranging from about 6 to 41 µm. At the same time, a 5-71 µm wide rim of equiaxed granular dolomite grew at the contact with CaCO3. Platinum markers showed that the original interface is located at the boundary between the granular and palisade-forming dolomite. In addition to dolomite, a 12-80 µm thick magnesio-calcite layer formed between the dolomite reaction rims and the calcite single crystals. All reaction products show at least an axiotactic crystallographic relationship with respect to calcite reactant, while full topotaxy to calcite prevails within the granular dolomite and magnesio-calcite. Dolomite grains frequently exhibit growth twins characterized by a rotation of 180° around one of the equivalent axis. From mass balance considerations, it is inferred that the reaction rim of dolomite grew by counter diffusion of MgO and CaO. Assuming an Arrhenius-type temperature dependence, activation energies for diffusion of CaO and MgO are E a (CaO) = 192 ± 54 kJ/mol and E a (MgO) = 198 ± 44 kJ/mol, respectively.

Improving production technology of tube steel grades in converter process

Directory of Open Access Journals (Sweden)

P. V. Kovalev

2016-10-01

Full Text Available Nature of formation and evolution special features of nonmetallic inclusions during ladle refining of converter HSLA steels for pipelines have been studied. Nonmetallic inclusions of the CaO-2O3-MgO system, close to calcium monoaluminate CaO∙Al2O3 with up to 5-6% of MgO, have been found as favorable from morphology point of view. These small inclusions nucleate on endogenous MgO substrates at sufficient high content of calcium in steel melt. Hot rolled plates can be rejected due to the coarse calcium bi- and hexa-aluminate inclusions (CaO∙22O3 and CaO∙62O3, usually containing exogenous MgO. These coarse inclusions form under calcium deficiency conditions, especially in the case of longtime steel holding in a ladle.

Electron microscopy and positron annihilation study of CdSe nanoclusters embedded in MgO

NARCIS (Netherlands)

van Huis, M.A.; van Veen, A.; Schut, H.; Eijt, S.W.H.; Kooi, B.J.; de Hosson, J.T.M.

CdSe nanoclusters are created in MgO by means of co-implantation of 280 keV, 1 x 10(16) Cd ions cm(-2) and 210 keV, 1 x 10(16) Se ions cm(-2) in single crystals of MgO(001) and subsequent thermal annealing at a temperature of 1300 K, The structural properties and the orientation relationship between

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

KAUST Repository

Yadav, Manoj Kumar; Vovusha, Hakkim; Sanyal, Biplab

2016-01-01

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

Size-dependent structure of CdSe nanoclusters formed after ion implantation in MgO

International Nuclear Information System (INIS)

Huis, M.A. van; Veen, A. van; Schut, H.; Eijt, S.W.H.; Kooi, B.J.; Hosson, J.Th.M. de

2005-01-01

The band gap as well as the optical and structural properties of semiconductor CdSe nanoclusters change as a function of the nanocluster size. Embedded CdSe nanoclusters in MgO were created by means of sequential Cd and Se ion implantation followed by thermal annealing. Changes during annealing were monitored using optical absorption and positron annihilation spectroscopy. High-resolution TEM on cross-sections after annealing at a temperature of 1300 K showed that clusters with a size below 5 nm have the high-pressure rock-salt structure and are in a cube-on-cube orientation relation with MgO, whereas clusters larger than 5 nm adopt the stable wurtzite crystal structure and were observed in two different orientation relations with MgO

Ethanol-to-Butadiene Conversion over SiO2-MgO Catalysts: Synthesis-Structure-Performance Relationships

NARCIS (Netherlands)

Angelici, C.

2015-01-01

The work presented in this PhD Thesis provides new insights into the underlying reasons that make SiO2-MgO materials excellent catalysts for the ethanol-to-butadiene Lebedev process. In particular, the preparation technique of choice affects the structural properties of the resulting SiO2-MgO

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 «...

The investigation of radiation induced defects in MgO

International Nuclear Information System (INIS)

Puetz, M.

1990-05-01

In this paper Frenkel defects were induced in MgO by 3 MeV electrons at low temperature. These defects were investigated by measurements of the optical absorption, by investigating the lattice parameters and Huang diffuse scattering. (WL)

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

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Tanaka, Takahiro; Matsubara, Katsuki; Futamoto, Masaaki; Kirino, Fumiyoshi

2011-01-01

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) 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.

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.

The Effect of Mesoporous H-ZSM-5 Crystallinity as a CaO Support on the Transesterification of Used Cooking Oil

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Amalia Putri Purnamasari

2017-10-01

Full Text Available Transesterification of used cooking oil was carried out over calcium oxide supported on mesoporous H-ZSM-5 prepared from kaolin as solid base catalysts. Solid basic catalysts investigated in this study were characterized by XRD, FTIR spectroscopy, and N2 adsorption-desorption techniques. The XRD pattern showed peaks corresponding to the CaO and mesoporous ZSM-5 in the sample. The peak intensity of the CaO increased as CaO loading in ZSM-5 was increased. The characterization based on FTIR spectroscopy revealed that CaO/H-ZSM-5 solids have functional groups characteristics of both CaO and mesoporous H-ZSM-5 which appeared in the band at around  550 cm-1 and 480 cm-1. The isotherm of N2 adsorption-desorption of CaO/H-ZSM-5 indicated the type IV isotherm with the presence of hysteresis loop. For the catalytic activity, the biodiesel yield using catalyst of 10 % CaO/HZSM-5 (100 %, 30 % CaO/HZSM-5 (100 %, 50 % CaO/HZSM-5 (100 % were 24.34, 27.37, and 29.73 %, respectively. It also related with the basic active site, when loading CaO increased, the basic active site also increased. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 8th March 2017; Accepted: 9th March 2017; Available online: 27th October 2017; Published regularly: December 2017 How to Cite: Purnamasari, A.P., Sari, M.E.F., Kusumaningtyas, D.T., Suprapto, S., Hamid, A., Prasetyoko, D. (2017. The Effect of Mesoporous H-ZSM-5 Crystallinity as a CaO Support on the Transesterification of Used Cooking Oil. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 329-336 (doi:10.9767/bcrec.12.3.802.329-336

Nano SiO2 and MgO Improve the Properties of Porous β-TCP Scaffolds via Advanced Manufacturing Technology

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Chengde Gao

2015-03-01

Full Text Available 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.

SeO2 adsorption on CaO surface: DFT study on the adsorption of a single SeO2 molecule

Science.gov (United States)

Fan, Yaming; Zhuo, Yuqun; Lou, Yu; Zhu, Zhenwu; Li, Liangliang

2017-08-01

Selenium is a hazardous element in coal. During coal combustion, most of the selenium will convert to SeO2 in the flue gas. Ca-based adsorbents, especially CaO, have been considered as a potential sorbent to adsorb SeO2 due to its low cost. In this paper, the adsorption mechanisms of single SeO2 on CaO surface were investigated by density functional theory (DFT) calculation. Both the physisorption and chemisorption structures were determined. It has been identified that the adsorption of SeO2 on CaO surface is primarily chemisorption, while physisorption takes effects at the initial stage of the process. Under O2 atmosphere, selenate is hard to form. Most of the adsorption products are selenite. Additionally, the electron density maps were obtained to reveal the surface active sites. The partial density of states (PDOS) was calculated for analyzing the electronic structural change of SeO2 and CaO surface during adsorption. The results provide fundamental information of the adsorption process, which could be meaningful for the development of new absorbents.

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.

Formation and characterization of the MgO protecting layer deposited by plasma-enhanced metal-organic chemical-vapor deposition

CERN Document Server

Kang, M S; Byun, J C; Kim, D S; Choi, C K; Lee, J Y; Kim, K H

1999-01-01

MgO films were prepared on Si(100) and soda-lime glass substrates by using plasma-enhanced metal-organic chemical-vapor deposition. Various ratios of the O sub 2 /CH sub 3 MgO sup t Bu gas mixture and various gas flow rates were tested for the film fabrications. Highly (100)-oriented MgO films with good crystallinity were obtained with a 10 sccm CH sub 3 MgO sup t Bu flow without an O sub 2 gas flow. About 5 % carbon was contained in all the MgO films. The refractive index and the secondary electron emission coefficient for the best quality film were 1.43 and 0.45, respectively. The sputtering rate was about 0.2 nm/min for 10 sup 1 sup 1 cm sup - sup 3 Ar sup + ion density. Annealing at 500 .deg. C in an Ar ambient promoted the grain size without inducing a phase transition.

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.

Additional lime of CaO in rearing medium with salinity for growing of catfish Pangasius hypopthalmus

Directory of Open Access Journals (Sweden)

Yuni Puji Hastuti

2013-11-01

Full Text Available Catfish juvenile quality improvements sought through the addition of lime to the availability of minerals in the body. Media maintenance is set at 4‰ salinity aims to reduce the level of osmotic work to reduce energy used for osmoregulation and can be allocated to the growth of catfish. Juvenile-sized fish used 2.59±0.02 cm and weights 0.13±0.01 g. Aquarium measuring 20×20×20 cm3 used 15 units, filled with water salinity of 4% as 6 L per unit, and added lime CaO appropriate treatment. During the study, the fish were fed with 28% protein content three times a day with FR 5%. Addition of CaO treatment dose 0 mg/L, 20 mg/L, 40 mg/L, 60 mg/L, 80 mg/L result in the survival rate of 100%, 100%, 100%, 96.29%, and 100% (p>0.05. The growth rate of daily weight 5.196%, 5.212%, 6.596%, 5.35% and 5.101% (p>0.05. Long absolute yield significantly different values are 1.451 cm, 1.518 cm, 1.964 cm, 1.71 cm, and 1.546 cm (p<0.05. During the study, the water quality is within the range that can be tolerated by catfish juvenile. The use of lime in the salinity of 4% is suggested as many as 40 mg/L CaO with the turnover of water every day and feeding enough.Keywords: CaO, salinity, growth, Pangasius hypopthalmus

The occurrence and origin of celestite in the Abolfares region, Iran: Implications for Sr-mineralization in Zagros fold belt (ZFB)

Science.gov (United States)

Pourkaseb, Houshang; Zarasvandi, Alireza; Rezaei, Mohsen; Mahdavi, Reyhaneh; Ghanavati, Fatemeh

2017-10-01

The major celestite deposits in Zagros Fold belt are associated with coastal marine carbonate and evaporate sediments of Oligo-Miocene Asmari and Lower Miocene Ghachsaran Formations. In the Abolfares region, celestite mineralization is extended in the western limb of Bangestan anticline in the carbonates of Early Miocene (middle part of Asmari Formation), underlying by dolomitic carbonates of Burdigalian. From bottom to top three main types of mineralization can be distinguished in the study area: (1) layer texture resulting from replacement of algal limestone by celestite minerals with some parts showing idiomorphic crystals (geodes) along the walls of the cavities, (2) celestite occurrence as irregular massive shape interconnected small crystals and nodules, and (3) celestite mineralization associated with steeply dipping veins and open space fracture fillings, resulting from late-stage epigenetic processes. Highlightly, the ore-hosting carbonate rocks were deposited in an intertidal - supratidal protected setting with hypersaline conditions, in accordance with other celestite deposits of the Zagros Fold belt. The abundance of diagenetic crystallization rhythmites, carbonate and anhydrite inclusions as confirmed by Laser Raman spectroscopy analysis, high Sr/Ba values (average; 8726.1) and strong negative correlations between SO3 vs CaO (R2 = 0.98), SrO vs CaO (R2 = 0.96) with positive correlations between Ba vs SrO (R2 = 0.54) and SO3 vs SrO (R2 = 0.98) highlight the role of high Sr late-diagenetic brines in replacement of carbonates with celestite minerals. It seems that the inception of compressional folding during or soon after the deposition of the Asmari Formation in the carbonate platform at the margin of NW-trending basin in the foreland of the Zagros orogenic belt lead to the upward refluxing of penetrated high-Sr diagenetic brines and celestite mineralization.

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.

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...... and interface structure of supported nanoparticles in a controlled environment [7]. This allows for a deeper understanding of the dynamic response of the surface and interface to changes in gas composition, pressure and temperature. Additionally, an Ultra High Vacuum (UHV) TEM has been used in order to have...... a higher degree of control of the initial state and probe the low-pressure regime. This combination is a powerful toolbox for charactering the behavior of the mobility of atomic species at the MgO surface leading to the formation of nanorods. Figure 1 shows Au particles on MgO cubes being irradiated...

Depth-selective 2D-ACAR and coincidence Doppler investigation of embedded Au nanocrystals in MgO

International Nuclear Information System (INIS)

Eijt, S.W.H.; Veen, A. van; Falub, C.V.; Schut, H.; Huis, M.A. van; Mijnarends, P.E.

2004-01-01

We present a depth-selective 2D-ACAR and two-detector Doppler broadening study on Au nanocrystals in monocrystalline MgO(100), produced in sub-surface layers by ion implantation and subsequent thermal annealing to temperatures beyond the stability range of vacancy clusters in MgO. In contrast to the case of Li nanocrystals, it was found that positrons do not trap inside the Au nanocrystals, but only in defects at the nanocrystal-to-host interface (attached vacancy clusters). This is interpreted in terms of the positron affinity of Au, MgO and the defects. (orig.)

Depth-selective 2D-ACAR and coincidence Doppler investigation of embedded Au nanocrystals in MgO

Energy Technology Data Exchange (ETDEWEB)

Eijt, S.W.H.; Veen, A. van; Falub, C.V.; Schut, H.; Huis, M.A. van [Interfaculty Reactor Inst., Delft Univ. of Technology, Delft (Netherlands); Mijnarends, P.E. [Interfaculty Reactor Inst., Delft Univ. of Technology, Delft (Netherlands); Dept. of Physics, Northeastern Univ., Boston, MA (United States)

2004-07-01

We present a depth-selective 2D-ACAR and two-detector Doppler broadening study on Au nanocrystals in monocrystalline MgO(100), produced in sub-surface layers by ion implantation and subsequent thermal annealing to temperatures beyond the stability range of vacancy clusters in MgO. In contrast to the case of Li nanocrystals, it was found that positrons do not trap inside the Au nanocrystals, but only in defects at the nanocrystal-to-host interface (attached vacancy clusters). This is interpreted in terms of the positron affinity of Au, MgO and the defects. (orig.)

Resputtering effect during MgO buffer layer deposition by magnetron sputtering for superconducting coated conductors

Energy Technology Data Exchange (ETDEWEB)

Xiao, Shaozhu; Shi, Kai; Deng, Shutong; Han, Zhenghe [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Feng, Feng, E-mail: feng.feng@sz.tsinghua.edu.cn; Lu, Hongyuan [Division of Advanced Manufacturing, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Qu, Timing; Zhu, Yuping [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Huang, Rongxia [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

2015-07-15

In this study, MgO thin films were deposited by radio-frequency magnetron sputtering. The film thickness in the deposition area directly facing the target center obviously decreased compared with that in other areas. This reduction in thickness could be attributed to the resputtering effect resulting from bombardment by energetic particles mainly comprising oxygen atoms and negative oxygen ions. The influences of deposition position and sputtering pressure on the deposition rate were investigated. Resputtering altered the orientation of the MgO film from (111) to (001) when the film was deposited on a single crystal yttria-stabilized zirconia substrate. The density distribution of energetic particles was calculated on the basis of the measured thicknesses of the MgO films deposited at different positions. The divergence angle of the energetic particle flux was estimated to be approximately 15°. The energetic particle flux might be similar to the assisting ion flux in the ion beam assisted deposition process and could affect the orientation of the MgO film growth.

Lithium ion implantation effects in MgO (100)

NARCIS (Netherlands)

van Huis, MA; Fedorov, AV; van Veen, A; Labohm, F; Schut, H; Mijnarends, PE; Kooi, BJ; De Hosson, JTM; Triftshauser, W; Kogel, G; Sperr, P

2001-01-01

Single crystals of MgO (100) were implanted with 10(16) (6)Li ions cm(-2) at an energy of 30 keV. After ion implantation the samples were annealed isochronally in air at temperatures up to 1200K. After implantation and after each annealing step, the defect evolution was monitored with optical

Study of electron-beam-evaporated MgO films using electron diffraction, optical absorption and cathodoluminescence

Energy Technology Data Exchange (ETDEWEB)

Aboelfotoh, M.O.; Ramsey, J.N.

1982-05-21

Reflection high energy electron diffraction, optical absorption and cathodoluminescence were used to study MgO films deposited onto fused silica, single-crystal silicon and LiF substrates at various temperatures. Results showed that some of the same optical absorption and emission bands observed in X- or UV-irradiated, additively colored or mechanically deformed MgO crystals were observed in evaporated MgO films. The peak positions and the relative peak intensities of the optical absorption and emission bands depended on the substrate temperature during film deposition as well as on the structure of the film. The effect of heating the films in air and vacuum on the optical absorption and emission bands is also discussed.

Synthesis of Al₂Ca Dispersoids by Powder Metallurgy Using a Mg-Al Alloy and CaO Particles.

Science.gov (United States)

Fujita, Junji; Umeda, Junko; Kondoh, Katsuyoshi

2017-06-28

The elemental mixture of Mg-6 wt %Al-1 wt %Zn-0.3 wt %Mn (AZ61B) alloy powder and CaO particles was consolidated by an equal-channel angular bulk mechanical alloying (ECABMA) process to form a composite precursor. Subsequently, the precursor was subjected to a heat treatment to synthesize fine Al₂Ca particles via a solid-state reaction between the Mg-Al matrix and CaO additives. Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and electron probe micro-analysis on the precursor indicated that 4.7-at % Al atoms formed a supersaturated solid solution in the α-Mg matrix. Transmission electron microscopy-EDS and X-ray diffraction analyses on the AZ61B composite precursor with 10-vol % CaO particles obtained by heat treatment confirmed that CaO additives were thermally decomposed in the Mg-Al alloy, and the solid-soluted Ca atoms diffused along the α-Mg grain boundaries. Al atoms also diffused to the grain boundaries because of attraction to the Ca atoms resulting from a strong reactivity between Al and Ca. As a result, needle-like (Mg,Al)₂Ca intermetallics were formed as intermediate precipitates in the initial reaction stage during the heat treatment. Finally, the precipitates were transformed into spherical Al₂Ca particles by the substitution of Al atoms for Mg atoms in (Mg,Al)₂Ca after a long heat treatment.

Thermoluminescence properties of CaO powder obtained from chicken eggshells

International Nuclear Information System (INIS)

Nagabhushana, K.R.; Lokesha, H.S.; Satyanarayana Reddy, S.; Prakash, D.; Veerabhadraswamy, M.; Bhagyalakshmi, H.; Jayaramaiah, J.R.

2017-01-01

Eggshell wastage has created serious problem in disposal of the food processing industry which has been triggered the thoughts of researchers to use wasted eggshells as good source of calcium. In the present work, calcium oxide (CaO) has been synthesized by combustion process in furnace (F–CaO) and microwave oven (M–CaO) using the source of chicken eggshells. The obtained F–CaO and M–CaO are characterized by XRD, SEM with EDX and thermoluminescence (TL) technique. XRD pattern of both the samples show cubic phase with crystallite size 45–52 nm. TL glow curves are recorded for various gamma radiation dose (300–4000 Gy). Two TL glows, a small peak at 424 K and stronger peak at 597 K are observed. TL response of M–CaO is 2.67 times higher than F–CaO sample. TL kinetic parameters are calculated by computerized curve deconvolution analysis (CCDA) and discussed. - Highlights: • Calcium oxide powders have been synthesized using chicken egg shells as raw material. • Crystallite size was found to be 45–52 nm. • CaO derived from eggshells shows good thermoluminescence TL response. • TL response of the M–CaO is 2.67 times higher than the F–CaO sample.

Fabrication of Nd:YAG transparent ceramics with both TEOS and MgO additives

International Nuclear Information System (INIS)

Yang Hao; Qin Xianpeng; Zhang Jian; Wang Shiwei; Ma Jan; Wang Lixi; Zhang Qitu

2011-01-01

Research highlights: → It is well known that the use of TEOS as sintering aid is required to reach fully dense and transparent Nd:YAG ceramics. However, it is difficult to produce high quality transparent Nd:YAG ceramics only using TEOS as sintering aid. In this present work, high quality transparent Nd:YAG ceramic was fabricated using both TEOS and MgO as sintering aids. There have been few reports that both TEOS and MgO were co-added as sintering aids in YAG or Nd:YAG transparent ceramics to date. The transmittance of Nd:YAG ceramic is 83.8% at 1064 nm. The effect of MgO on the optical properties of transparent ceramics was also studied. - Abstract: Neodymium doped YAG transparent ceramics were fabricated by vacuum reactive sintering method using commercial α-Al 2 O 3 , Y 2 O 3 and Nd 2 O 3 powders as the starting materials with both tetraethyl orthosilicate (TEOS) and MgO as sintering aids. The morphologies and microstructure of the powders and Nd:YAG transparent ceramics were investigated. Fully dense Nd:YAG ceramics with average grain size of ∼10 μm were obtained by vacuum sintering at 1780 deg. C for 8 h. No pores and grain-boundary phases were observed. The in-line transmittance of the ceramic was 83.8% at 1064 nm.

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...

Morphological and optical studies of zinc oxide doped MgO

Energy Technology Data Exchange (ETDEWEB)

Othman, Zayani Jaafar, E-mail: jaafar.zayani@yahoo.fr; Matoussi, Adel

2016-06-25

This paper reports morphological and optical characterizations of sintered (ZnO){sub 1−x}(MgO){sub x} composite materials. The effects of MgO doping content on these pellets properties have been analyzed. The SEM observations have shown rougher surfaces of the samples covered by grains having prismatic shapes and different sizes. From reflectance and absorption measurements, we have determined the band gap energy which tends to augment from 3.287 to 3.827 eV as the doping content increases. This widening of the optical band gap is explained by the Burstein-Moss effect which causes a significant increase of electron concentration (2.89 10{sup 18}−5.1910{sup 20} cm{sup −3}). In addition, the absorption coefficient, Urbach energy, optical constants (refractive index, extinction coefficient, dielectric constant) and dispersion parameters, such as E{sub 0} (single-oscillator energy), E{sub d} (dispersive energy) were determined of the (ZnO){sub 1−x}(MgO){sub x} composites and analyzed. - Highlights: • (ZnO){sub 1−x}(MgO){sub x} composites were synthesized by solid state sintering method. • MgO doping increased the band gap energy. • SEM observations have shown a decrease of grain sizes when the MgO doping increases. • Optical constants and dispersion parameters were determined and analyzed.

Model surface studies of metal oxides: Adsorption of water and methanol on ultrathin MgO films on Mo(100)

International Nuclear Information System (INIS)

Wu, M.; Estrada, C.A.; Corneille, J.S.; Goodman, D.W.

1992-01-01

Model surface studies of magnesium oxide have been carried out using surface sensitive techniques. Ultrathin MgO films have been synthesized under ultrahigh vacuum (UHV) conditions by thermally evaporating Mg onto Mo(100) in the presence of oxygen. Low-energy electron diffraction (LEED) studies indicate that the MgO films grow epitaxially with the (100) face of MgO oriented parallel to Mo(100). The MgO films, prepared under optimum synthesis conditions, have essentially one-to-one stoichiometry, are nearly free from pointlike surface defects, and have properties essentially identical to those of bulk, single-crystal MgO. Adsorption of water and methanol onto the MgO films has been studied using high-resolution electron energy-loss spectroscopy (HREELS) and temperature programmed desorption (TPD). In order to circumvent the difficulty associated with intense multiple surface optical phonon (Fuchs--Kliewer modes) losses, a new approach to acquisition of HREELS data has been demonstrated. This new approach enables the direct observation of weak loss features due to excitation of the adsorbates without serious interference from multiple phonon losses. Our HREELS studies show that water and methanol undergo heterolytic dissociation, leading to the formation of hydroxyl and methoxy species, respectively

Combination of Palm Kernel Husk Ash (PKHA) and Free Lime (CaO ...

African Journals Online (AJOL)

Almost all admixtures used in concrete construction in Nigeria are imported. In this study, various proportions of free Lime (CaO), Palm Kernel Husk Ash (PKHA) and Ordinary Portland Cement (OPC) were mixed and the setting times of various mix proportions were determined and compared with that of only OPC.

(2008) SWJ:121-126 Evolutionary Trend of The Jarawa Younger ...

African Journals Online (AJOL)

Dr. Ahmed

2008) SWJ:121-126. Evolutionary Trend of The Jarawa Younger Granite. TABLE 1. CHEMICAL COMPOSITION OF HORNBLENDE PORPHYRY GRANITES. Sample. No. Oxide (%). K2O CaO MgO FeO Fe2O3. AL2O3 Na2O PbO. JA-HP.

AMOC studies of positronium in fine MgO powder

International Nuclear Information System (INIS)

Waeyenberge, B. van; Dauwe, C.

2001-01-01

A first set of AMOC spectra on fine powdered MgO were measured at the Stuttgart relativistic positron beam facility. A special AMOC spectrometer was set up in order to determine the long lifetimes of ortho-positronium in the powder cavities. The spectra were taken on pellets of pressed powder in air and in an oxygen atmosphere to ensure ortho- to para-positronium conversion. An analysis of the data is made in the light of previous lifetime measurements on MgO. Here the lifetime spectrum was fitted with an age dependent lifetime describing the slow thermalisation of epithermal ortho-positronium between the powder grains. Based on the lifetime spectrum of the integrated AMOC spectra the data could not discriminate between a 5-component model and a model including slow positronium thermalisation. On the other hand, analysis of the age dependent line shape parameter shows better variances for a thermalisation model. (orig.)

AMOC studies of positronium in fine MgO powder

Energy Technology Data Exchange (ETDEWEB)

Waeyenberge, B. van; Dauwe, C. [Ghent Univ. (Belgium). Dept. of Subatomic and Radiation Physics; Stoll, H. [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

2001-07-01

A first set of AMOC spectra on fine powdered MgO were measured at the Stuttgart relativistic positron beam facility. A special AMOC spectrometer was set up in order to determine the long lifetimes of ortho-positronium in the powder cavities. The spectra were taken on pellets of pressed powder in air and in an oxygen atmosphere to ensure ortho- to para-positronium conversion. An analysis of the data is made in the light of previous lifetime measurements on MgO. Here the lifetime spectrum was fitted with an age dependent lifetime describing the slow thermalisation of epithermal ortho-positronium between the powder grains. Based on the lifetime spectrum of the integrated AMOC spectra the data could not discriminate between a 5-component model and a model including slow positronium thermalisation. On the other hand, analysis of the age dependent line shape parameter shows better variances for a thermalisation model. (orig.)

Microstructure and magnetic properties of FeCo epitaxial thin films grown on MgO single-crystal substrates

International Nuclear Information System (INIS)

Shikada, Kouhei; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

2009-01-01

FeCo epitaxial films were prepared on MgO(100), MgO(110), and MgO(111) substrates by ultrahigh vacuum molecular beam epitaxy. FeCo thin films with (100), (211), and (110) planes parallel to the substrate surface grow on respective MgO substrates. FeCo/MgO interface structures are studied by high-resolution cross-sectional transmission electron microscopy and the epitaxial growth mechanism is discussed. Atomically sharp boundaries are recognized between the FeCo thin films and the MgO substrates where misfit dislocations are introduced in the FeCo thin films presumably to decrease the lattice misfits. Misfit dislocations are observed approximately every 9 and 1.4 nm in FeCo thin film at the FeCo/MgO(100) and the FeCo/MgO(110) interfaces, respectively. X-ray diffraction analysis indicates that the lattice spacing measured parallel to the single-crystal substrate surfaces are in agreement within 0.1% with those of the respective bulk values of Fe 50 Co 50 alloy crystal, showing that the FeCo film strain is very small. The magnetic anisotropies of these epitaxial films basically reflect the magnetocrystalline anisotropy of bulk FeCo alloy crystal

Experimental study of influence characteristics of flue gas fly ash on acid dew point

Science.gov (United States)

Song, Jinhui; Li, Jiahu; Wang, Shuai; Yuan, Hui; Ren, Zhongqiang

2017-12-01

The long-term operation experience of a large number of utility boilers shows that the measured value of acid dew point is generally lower than estimated value. This is because the influence of CaO and MgO on acid dew point in flue gas fly ash is not considered in the estimation formula of acid dew point. On the basis of previous studies, the experimental device for acid dew point measurement was designed and constructed, and the acid dew point under different smoke conditions was measured. The results show that the CaO and MgO in the flue gas fly ash have an obvious influence on the acid dew point, and the content of the fly ash is negatively correlated with the temperature of acid dew point At the same time, the concentration of H2SO4 in flue gas is different, and the acid dew point of flue gas is different, and positively correlated with the acid dew point.

Parental magmas of Mare Fecunditatis - Evidence from pristine glasses

International Nuclear Information System (INIS)

Jin, Y.; Taylor, L.A.

1990-01-01

Results are presented on the petrography and electron microprobe analyses of 14 discrete glass beads from the Luna 16 core sample (21036,15) from Mare Fecunditatis regolith, that were previously characterized as representing pristine glasses. Compared to Apollo pristine glasses analyzed by Delano (1986), the Luna 16 pristine glasses have higher CaO and Al2O3 contents but lower MgO and Ni. On the basis of their contents of MgO, FeO, Al2O3, and CaO, these pristine glasses could be divided into two groups, A and B. It is suggested that at least two parental magmas are needed to explain the chemical variations among these glasses. The Group B glasses appear to represent primitive parental magma that evolved by olivine fractionation to the compositions of the Luna 16 aluminous mare basalts, whereas the Group A volcanic glasses may represent an unusual new basalt magma type that contains a high plagioclase component. 14 refs

Retail marketing a in-store promotion společnosti Samsung Electronics Czech and Slovak s.r.o.

OpenAIRE

Košťál, Michal

2015-01-01

This thesis deals with the retail marketing and the in-store promotion. It is prima-rily focused on merchandising, sales promotion and other selected activities. The work itself is devoted to Samsung Electronics Czech and Slovak s.r.o. and is mostly based on a practical experience gained from a position of an employee. Firstly, the amount of investments in marketing of Samsung in comparison with the competition is introduced. The following part describes the basic retail acti-vities across th...

Reporting v spoločnosti BSH domácí spotřebiče s.r.o.

OpenAIRE

Cinkaničová, Martina

2011-01-01

Diploma thesis is focused on reporting process in the sale company BSH domácí spotřebiče s.r.o. In the beginning it explains differences between management, financial and tax accounting. There is the aim to emphasize the importance of management accounting in the broader sense, in the process of strategic, tactic and operative cost controlling. The source of information for cost accounting is controlling. Controller, in retrospect to content of diploma thesis, intermediate the results through...

Neutron monochromators of BeO, MgO and ZnO single crystals

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Habib, N. [Reactor Physics Department, NRC, AEAE, Cairo (Egypt); Bashter, I.I. [Physics Department, Faculty of Science, Zagazig University (Egypt); Morcos, H.N.; El-Mesiry, M.S. [Reactor Physics Department, NRC, AEAE, Cairo (Egypt); Mansy, M.S., E-mail: mohamedmansy_np@yahoo.com [Physics Department, Faculty of Science, Zagazig University (Egypt)

2014-05-21

The monochromatic features of BeO, MgO and ZnO single crystals are discussed in terms of orientation, mosaic spread, and thickness within the wavelength band from 0.05 up to 0.5 nm. A computer program MONO, written in “FORTRAN”, has been developed to carry out the required calculations. Calculation shows that a 5 mm thick MgO single crystal cut along its (2 0 0) plane having mosaic spread of 0.5° FWHM has the optimum parameters when it is used as a neutron monochromator. Moreover, at wavelengths shorter than 0.24 nm the reflected monochromatic neutrons are almost free from the higher order ones. The same features are seen with BeO (0 0 2) with less reflectivity than that of the former. Also, ZnO cut along its (0 0 2) plane is preferred over the others only at wavelengths longer than 0.20 nm. When the selected monochromatic wavelength is longer than 0.24 nm, the neutron intensities of higher orders from a thermal reactor flux are higher than those of the first-order one. For a cold reactor flux, the first order of BeO and MgO single crystals is free from the higher orders up to 0.4 nm, and ZnO at wavelengths up to 0.5 nm. - Highlights: • Monochromatic features of BeO, MgO and ZnO single crystals. • Calculations of neutron reflectivity using a computer program MONO. • Optimum mosaic spread, thickness and cutting plane of single crystals.

Chaos and fractals. Applications to nuclear engineering; Caos y fractales. Aplicaciones en ingenieria nuclear

Energy Technology Data Exchange (ETDEWEB)

Clausse, A; Delmastro, D F

1991-12-31

This work presents a description of the research lines carried out by the authors on chaos and fractal theories, oriented to the nuclear field. The possibilities that appear in the nuclear security branch where the information deriving from chaos and fractal techniques may help to the development of better criteria and more reliable designs, are of special importance. (Author). [Espanol] En este trabajo se presenta una descripcion de las lineas de investigacion que los autores estan llevando a cabo en teoria de caos y fractales orientadas al campo nuclear. Es de especial importancia las posibilidades que se abren en el area de la seguridad nuclear, en donde la informacion proveniente de las tecnicas de caos y fractales pueden ayudar al desarrollo de mejores criterios y disenos mas confiables. (Autor).

Periodic DFT study of acidic trace atmospheric gas molecule adsorption on Ca- and Fe-doped MgO(001) surface basic sites.

Science.gov (United States)

Baltrusaitis, Jonas; Hatch, Courtney; Orlando, Roberto

2012-08-02

The electronic properties of undoped and Ca- or Fe-doped MgO(001) surfaces, as well as their propensity toward atmospheric acidic gas (CO2, SO2, and NO2) uptake was investigated with an emphasis on gas adsorption on the basic MgO oxygen surface sites, O(surf), using periodic density functional theory (DFT) calculations. Adsorption energy calculations show that MgO doping will provide stronger interactions of the adsorbate with the O(surf) sites than the undoped MgO for a given adsorbate molecule. Charge transfer from the iron atom in Fe-doped MgO(001) to NO2 was shown to increase the binding interaction between adsorbate by an order of magnitude, when compared to that of undoped and Ca-doped MgO(001) surfaces. Secondary binding interactions of adsorbate oxygen atoms were observed with surface magnesium sites at distances close to those of the Mg-O bond within the crystal. These interactions may serve as a preliminary step for adsorption and facilitate further adsorbate transformations into other binding configurations. Impacts on global atmospheric chemistry are discussed as these adsorption phenomena can affect atmospheric gas budgets via altered partitioning and retention on mineral aerosol surfaces.

Characterization and evaluation of antibacterial activity of plant mediated calcium oxide (CaO) nanoparticles by employing Mentha pipertia extract

Science.gov (United States)

Ijaz, Umber; Bhatti, Ijaz Ahmed; Mirza, Saima; Ashar, Ambreen

2017-10-01

The antibacterial activity of green synthesized calcium oxide nanoparticles was investigated using leaf extract of Mentha piperita in this study. The synthesized nanomaterial was subjected to characterization using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive x-ray spectroscopy (EDX). The SEM images showed agglomeration of disc shaped nanoparticles, and FTIR and EDX spectroscopy indicated intensive peaks for calcium ions and oxygen. Subsequently, the potential of nanoscale CaO was also evaluated for antimicrobial index against E. coli using the well diffusion method. A maximum zone of inhibition up to 42 mm was observed when 100 µg ml-1 material was loaded with inoculum size 50 µl of E. coli in sunlight exposure of 5 h. The experimental conditions were optimized using a central composite design using a response surface methodology. The maximum antimicrobial index of the CaO nanoparticle was 6 mm as a result of the optimized response. Furthermore, the minimum inhibitory concentration of the CaO nanoparticle showed 25 µg ml-1, an effective initial concentration for E.coli removal. The results revealed that the CaO nanocomposite synthesized via a green route was a promising candidate for the removal of E. coli present in drinking water, which is an important fecal indicator.

Crystal orientation of monoclinic β-Ga2O3 thin films formed on cubic MgO substrates with a γ-Ga2O3 interfacial layer

Science.gov (United States)

Nakagomi, Shinji; Kokubun, Yoshihiro

2017-12-01

The crystal orientation relationship between β-Ga2O3 and MgO in β-Ga2O3 thin films prepared on (1 0 0), (1 1 1), and (1 1 0) MgO substrates was investigated by X-ray diffraction measurements and cross-sectional transmission electron microscopy images. The γ-Ga2O3 interfacial layer was present between β-Ga2O3 and MgO acted as a buffer to connect β-Ga2O3 on MgO. The following conditions were satisfied under each case: β-Ga2O3 (1 0 0)||MgO (1 0 0) and β-Ga2O3 [0 0 1]||MgO 〈0 1 1〉 for the formation of β-Ga2O3 on (1 0 0) MgO, and β-Ga2O3 (2 bar 0 1)||MgO (1 1 1) for the formation of β-Ga2O3 on (1 1 1) MgO, as well as each condition of β-Ga2O3 [0 1 0] (1 0 0)||MgO [ 1 bar 1 0 ] (0 0 1), β-Ga2O3 [0 1 0] (1 0 0)||MgO [ 0 1 bar 1 ] (1 0 0), and β-Ga2O3 [0 1 0] (1 0 0)||MgO [ 1 0 1 bar ] (0 1 0). β-Ga2O3 (1 bar 0 2)||MgO(1 1 0) and β-Ga2O3 [0 1 0] ⊥ MgO [0 0 1] for β-Ga2O3 formed on (1 1 0) MgO. The β-Ga2O3 formed on (1 1 1) MgO at 800 °C exhibited a threefold structure. The β-Ga2O3 formed on (1 1 0) MgO had a twofold structure but different by 90° from the result reported previously.

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.

Multishelled CaO Microspheres Stabilized by Atomic Layer Deposition of Al2 O3 for Enhanced CO2 Capture Performance.

Science.gov (United States)

Armutlulu, Andac; Naeem, Muhammad Awais; Liu, Hsueh-Ju; Kim, Sung Min; Kierzkowska, Agnieszka; Fedorov, Alexey; Müller, Christoph R

2017-11-01

CO 2 capture and storage is a promising concept to reduce anthropogenic CO 2 emissions. The most established technology for capturing CO 2 relies on amine scrubbing that is, however, associated with high costs. Technoeconomic studies show that using CaO as a high-temperature CO 2 sorbent can significantly reduce the costs of CO 2 capture. A serious disadvantage of CaO derived from earth-abundant precursors, e.g., limestone, is the rapid, sintering-induced decay of its cyclic CO 2 uptake. Here, a template-assisted hydrothermal approach to develop CaO-based sorbents exhibiting a very high and cyclically stable CO 2 uptake is exploited. The morphological characteristics of these sorbents, i.e., a porous shell comprised of CaO nanoparticles coated by a thin layer of Al 2 O 3 (<3 nm) containing a central void, ensure (i) minimal diffusion limitations, (ii) space to accompany the substantial volumetric changes during CO 2 capture and release, and (iii) a minimal quantity of Al 2 O 3 for structural stabilization, thus maximizing the fraction of CO 2 -capture-active CaO. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of CaO2 addition on anaerobic digestion of waste activated sludge at different temperatures and the promotion of valuable carbon source production under ambient condition.

Science.gov (United States)

Ping, Qian; Lu, Xiao; Zheng, Ming; Li, Yongmei

2018-06-06

The effect of calcium peroxide (CaO 2 ) addition on anaerobic digestion (AD) of waste activated sludge (WAS) at different temperatures (20 °C, 35 °C, and 55 °C) were investigated. The results show that CaO 2 addition had significant positive effect on short-chain fatty acids (SCFAs) production under ambient and mesophilic conditions. Polysaccharides and proteins embedded in extracellular polymeric substances (EPS) were effectively released from inner fraction to outer fraction, and non-biodegradable humic-like substances were decreased while easily biodegradable tryptophan-like proteins increased. These effects were most remarkable under ambient conditions. However, CaO 2 addition was unfavorable to thermophilic AD because of high free ammonia concentrations and the accumulation of humic-like substances. Temperature showed a stronger effect than CaO 2 on microbial community structure, but CaO 2 addition was more effective than temperature in enhancing hydrolytic and acidifying microorganisms. Predictive functional profiling indicated that microbial hydrolysis, metabolism and acidification were promoted by CaO 2 under ambient conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adsorption of SO{sub 2} on Li atoms deposited on MgO (1 0 0) surface: DFT calculations

Energy Technology Data Exchange (ETDEWEB)

Eid, Kh.M., E-mail: Kheid98@hotmail.com [Physics Department, Faculty of Education, Ain Shams University, Cairo 11757 (Egypt); Ammar, H.Y. [Department of Physics, Faculty of Science, Najran University, Najran 1988 (Saudi Arabia)

2011-05-01

The adsorption of sulfur dioxide molecule (SO{sub 2}) on Li atom deposited on the surfaces of metal oxide MgO (1 0 0) on both anionic and defect (F{sub s}-center) sites located on various geometrical defects (terrace, edge and corner) has been studied using density functional theory (DFT) in combination with embedded cluster model. The adsorption energy (E{sub ads}) of SO{sub 2} molecule (S-atom down as well as O-atom down) in different positions on both of O{sup -2} and F{sub s} sites is considered. The spin density (SD) distribution due to the presence of Li atom is discussed. The geometrical optimizations have been done for the additive materials and MgO substrate surfaces (terrace, edge and corner). The oxygen vacancy formation energies have been evaluated for MgO substrate surfaces. The ionization potential (IP) for defect free and defect containing of the MgO surfaces has been calculated. The adsorption properties of SO{sub 2} are analyzed in terms of the E{sub ads}, the electron donation (basicity), the elongation of S-O bond length and the atomic charges on adsorbed materials. The presence of the Li atom increases the catalytic effect of the anionic O{sup -2} site of MgO substrate surfaces (converted from physisorption to chemisorption). On the other hand, the presence of the Li atom decreases the catalytic effect of the F{sub s}-site of MgO substrate surfaces. Generally, the SO{sub 2} molecule is strongly adsorbed (chemisorption) on the MgO substrate surfaces containing F{sub s}-center.

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

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.

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.

Viability of Clostridium sporogenes spores after CaO hygienization of meat waste

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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.

Contribution à l'étude de l'immobilisation des ions plomb en solution ...

African Journals Online (AJOL)

DK

mesurée à l'aide d'un granulomètre laser. (MASTER .... 91. Tableau 1. Composition chimique de PN en poids. Elets P2O5. CaO. MgO CO2. SiO2 .... interactions entre adsorbats ..... heavy metal ions from water by using calcined phosphate.

The neutron transmission of single crystal MgO filters

International Nuclear Information System (INIS)

Carpenter, J.M.; Hilleke, R.O.

1989-01-01

We have measured and analyzed the wavelength dependence of the transmission probability of a beam of neutrons passing through a single crystal MgO filter at 77 K. The 12.7 cm filter transmits 70% or more of the incident beam at wavelengths greater than about 1.8 A. At shorter wavelengths the transmission probability drops sharply, with 50% transmission occurring at about 1.2 A, and 1% transmission for the range 0.1-0.4 A. We have determined that cooling the filter to 77 K improves the transmission of >1 A neutrons, while further cooling to 25 K shows little additional improvement, and no improvement for short wavelengths. We have identified the wavelengths of the sharp dips in the transmission found in this region caused by Bragg scattering in MgO. We also show how these peaks may be used to calibrate the wavelength scale of time-of-flight measurements taken on instruments using similar filters. (orig.)

A-axis oriented superconductive YBCO thin films. Growth mechanism on MgO substrate. [Y-Ba-Cu-O

Energy Technology Data Exchange (ETDEWEB)

Hamet, J F; Mercey, B; Hervieu, M; Poullain, G; Raveau, B [Centre de Materiaux Supraconducteurs, CRISMAT-ISMRa, 14 - Caen (France)

1992-08-01

The growth mechanism of a-axis oriented YBCO thin films has been studied by TEM. At 650degC, a disordered cubic perovskite is first formed with a[sub p]parallela[sub MgO], then a strained tetragonal a-axis oriented perovskite is observed, with c=3a[sub p], slightly misoriented with respect to MgO and showing a marquetry-like contrast. At 750degC, a [1anti 10] axis oriented perovskite is formed whose lattice exhibits a rotation with respect to MgO lattice, but also a tilting of the [CuO[sub 2

Effect of CaO addition on preparation of ferrotitanium from ilmenite by electrochemical reduction in CaCl_2−NaCl molten salt

International Nuclear Information System (INIS)

Xiong, Li; Hua, Yixin; Xu, Cunying; Li, Jian; Li, Yan; Zhang, Qibo; Zhou, Zhongren; Zhang, Yadong; Ru, Juanjian

2016-01-01

Ferro-titanium (FeTi) alloy was prepared successfully from synthesized ilmenite through electrochemical reduction method in equal-molar CaCl_2−NaCl molten salt at 973 K and a cell voltage of 3.2 V under inert atmosphere, where molybdenum rod and graphite were used as cathode and anode respectively. It is indicated that the CaO content in the molten salt has an appreciable effect on the phase transformation of reactants occurring in the electrolytic process. The optimized CaO content in the molten salt is 1 mol% and this suitable content of CaO can significantly improve the reduction rate of ilmenite. The micromorphology of the ferrotitanium product is porous with the amount of 1 mol%CaO addition. It is observed that the particles of ferrotitanium had a uniform size in the initial period of time. Along with the electrolysis time extension, however, the particles connected with each other to generate strips and then form a honeycomb structure. These findings provide a basis for scientifically discussion on the optimization of CaO addition amount during the electrochemical reduction of ilmenite and other oxides in molten salts. - Highlights: • Ferro-titanium was prepared from synthesized ilmenite in CaCl_2−NaCl molten salt. • CaO content has appreciable effect on the phase transformation of ilmenite reactant. • The optimized CaO content is 1 mol% which can significantly improve reaction rate. • The products are connected with each other to form strips as electrolysis time.

Flexible MgO Barrier Magnetic Tunnel Junctions.

Science.gov (United States)

Loong, Li Ming; Lee, Wonho; Qiu, Xuepeng; Yang, Ping; Kawai, Hiroyo; Saeys, Mark; Ahn, Jong-Hyun; Yang, Hyunsoo

2016-07-01

Flexible MgO barrier magnetic tunnel junction (MTJ) devices are fabricated using a transfer printing process. The flexible MTJ devices yield significantly enhanced tunneling magnetoresistance of ≈300% and improved abruptness of switching, as residual strain in the MTJ structure is released during the transfer process. This approach could be useful for flexible electronic systems that require high-performance memory components. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

A Comparative Study of Chemically and Biologically Synthesized MgO Nanomaterial for Liquefied Petroleum Gas Detection

Science.gov (United States)

Thirupathi, Rampelly; Solleti, Goutham; Sreekanth, Tirumala; Sadasivuni, Kishor Kumar; Venkateswara Rao, Kalagadda

2018-03-01

The exceptional chemical and physical properties of nanostructured materials are extremely suitable for designing new and enhanced sensing devices, particularly gas sensors and biosensors. The present work describes the synthesis of magnesium oxide (MgO) nanoparticles through two methods: a green synthesis using aloe vera plant extract and a chemical method using a glycine-based solution combustion route. In a single step, the extracted organic molecules from aloe vera plants were used to reduce metal ions by the green method. MgO nanoparticles were coated onto the interdigital electrode using the drop-drying method. The dynamic gas-sensing characteristics were measured for liquefied petroleum gas (LPG) at different concentrations and various temperatures. The MgO nanoparticles were characterized by using x-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy to determine the size and structure of the particles. The product's functional properties were analyzed by Fourier transform-infrared spectroscopy and UV-visible spectroscopy. We found that the LPG sensing behavior of biologically synthesized MgO registers excellent sensitivity at various operating temperatures.

Solar light-facilitated oxytetracycline removal from the aqueous phase utilizing a H2O2/ZnWO4/CaO catalytic system

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Pankaj Raizada

2017-09-01

Full Text Available A CaO-supported ZnWO4 nanocomposite (ZnWO4/CaO was successfully synthesized using a novel hydrothermal method and was characterized by scanning electron microscopy (SEM, tunnelling electron microscopy (TEM, X-ray diffraction (XRD, electron diffraction X-ray (EDX, Fourier transform infrared spectroscopy (FTIR and UV–visible (UV–vis spectral analysis. The ZnWO4/CaO composites exhibited rod-like morphologies with variable lengths from 45 nm to 147 nm and diameters from 26 nm to 36 nm. The catalytic efficiency of the synthesized ZnWO4/CaO composites was displayed for the photodegradation of oxytetracycline (OTC antibiotic from the aqueous phase. The synergistic degradation of OTC was investigated in the presence of H2O2 and ZnWO4/CaO. The rate of photodegradation followed pseudo-first-order kinetics. The antibiotic removal was strongly influenced by the catalyst loading, H2O2 concentration, pH and OTC concentration. Using a solar/H2O2/ZnWO4/CaO catalytic system, 85% COD removal was attained for OTC degradation in 210 min. The oxidative degradation occurred through hydroxyl radicals. The prepared nanocomposites possessed high recyclability and were easily separated from the aqueous solution by a simple sedimentation process.

SeO{sub 2} adsorption on CaO surface: DFT study on the adsorption of a single SeO{sub 2} molecule

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Fan, Yaming; Zhuo, Yuqun; Lou, Yu; Zhu, Zhenwu [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Li, Liangliang [Key Laboratory of Advanced Materials, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China)

2017-08-15

Highlights: • Adsorption mechanisms of SeO{sub 2} on CaO surface under O{sub 2} were firstly studied by DFT. • The adsorption energies, bond length and electron density maps were calculated. • The electronic structure changes upon adsorption were studied. - Abstract: Selenium is a hazardous element in coal. During coal combustion, most of the selenium will convert to SeO{sub 2} in the flue gas. Ca-based adsorbents, especially CaO, have been considered as a potential sorbent to adsorb SeO{sub 2} due to its low cost. In this paper, the adsorption mechanisms of single SeO{sub 2} on CaO surface were investigated by density functional theory (DFT) calculation. Both the physisorption and chemisorption structures were determined. It has been identified that the adsorption of SeO{sub 2} on CaO surface is primarily chemisorption, while physisorption takes effects at the initial stage of the process. Under O{sub 2} atmosphere, selenate is hard to form. Most of the adsorption products are selenite. Additionally, the electron density maps were obtained to reveal the surface active sites. The partial density of states (PDOS) was calculated for analyzing the electronic structural change of SeO{sub 2} and CaO surface during adsorption. The results provide fundamental information of the adsorption process, which could be meaningful for the development of new absorbents.

Single-crystalline MgAl2O4 spinel nanotubes using a reactive and removable MgO nanowire template

International Nuclear Information System (INIS)

Fan Hongjin; Knez, Mato; Scholz, Roland; Nielsch, Kornelius; Pippel, Eckhard; Hesse, Dietrich; Goesele, Ulrich; Zacharias, Margit

2006-01-01

Using MgO nanowires as a reactive template, we fabricated for the first time single-crystal MgAl 2 O 4 spinel nanotubes through an interfacial solid-state reaction of MgO-Al 2 O 3 core-shell nanowires. Single-crystal MgO nanowires are coated with a conformal thin layer of amorphous Al 2 O 3 via atomic layer deposition. Subsequent annealing at 700 deg. C activates the interfacial reaction between MgO and Al 2 O 3 , transforming the alumina shell into a spinel shell. Finally, after etching away the remaining MgO core in ammonia sulfuric solution, MgAl 2 O 4 spinel nanotubes are obtained. As a transition from conventional planar spinel layers via thin-film interface reactions, our result might open a window for the fabrication of a wide variety of MgO-based spinel one-dimensional nanostructures

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.

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).

MgO Nanoparticle Modified Anode for Highly Efficient SnO2-Based Planar Perovskite Solar Cells.

Science.gov (United States)

Ma, Junjie; Yang, Guang; Qin, Minchao; Zheng, Xiaolu; Lei, Hongwei; Chen, Cong; Chen, Zhiliang; Guo, Yaxiong; Han, Hongwei; Zhao, Xingzhong; Fang, Guojia

2017-09-01

Reducing the energy loss and retarding the carrier recombination at the interface are crucial to improve the performance of the perovskite solar cell (PSCs). However, little is known about the recombination mechanism at the interface of anode and SnO 2 electron transfer layer (ETL). In this work, an ultrathin wide bandgap dielectric MgO nanolayer is incorporated between SnO 2 :F (FTO) electrode and SnO 2 ETL of planar PSCs, realizing enhanced electron transporting and hole blocking properties. With the use of this electrode modifier, a power conversion efficiency of 18.23% is demonstrated, an 11% increment compared with that without MgO modifier. These improvements are attributed to the better properties of MgO-modified FTO/SnO 2 as compared to FTO/SnO 2 , such as smoother surface, less FTO surface defects due to MgO passivation, and suppressed electron-hole recombinations. Also, MgO nanolayer with lower valance band minimum level played a better role in hole blocking. When FTO is replaced with Sn-doped In 2 O 3 (ITO), a higher power conversion efficiency of 18.82% is demonstrated. As a result, the device with the MgO hole-blocking layer exhibits a remarkable improvement of all J-V parameters. This work presents a new direction to improve the performance of the PSCs based on SnO 2 ETL by transparent conductive electrode surface modification.

Optical features of C, N, Mn implanted MgO films

International Nuclear Information System (INIS)

Dorosinets, V.A.; Dobrinets, I.A.; Wieck, A.

2013-01-01

Optical absorption and Raman spectra investigations of C/ N/ Mn implanted MgO films have been investigated. The spectra reveal a surface modification and a dependence of the defect formation mechanism on the ion type and the annealing regime. (authors)

Effect of Precursor Concentration of MgO nanostructure by using Sol-Gel Method

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V.T. Srisuvetha

2017-04-01

Full Text Available MgO thin flims have been prepared on substrates by a novel and simple sol-gel method using magnesium nitrate and collusion as starting material.The MgO nano catalyst with good sensor crystallization were obtained after annealing at 100°C Magnesium oxide was prepared by sol-gel method. The method involves the hydrolysis of magnesium alkoxide in the presence of acid or basic catalysts followed by a Oxalic acid reaction. The synthesized solids were characterized by IR spectroscopy X-ray diffraction electron microscopy. Ultraviolet visible absorbance measurement photoluminescence and Raman scattering spectra. X-ray diffraction (XRD characterization showed the formation of smaller particles after sol gel irradiation the structure and morphology of the MgO particles were analyzed byXRD. These articles were used for FTIR spectroscopic measurement and spectra were collected. In EDS we calculated the peak intensity the SEM the images of metal oxide.UV (Ultra Violet refers to adsorption spectroscopy optical properties of assorption, band gap energy.This means if use light in the visible and adjacent ranges.

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

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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.

Structural insights into the light-driven auto-assembly process of the water-oxidizing Mn4CaO5-cluster in photosystem II.

Science.gov (United States)

Zhang, Miao; Bommer, Martin; Chatterjee, Ruchira; Hussein, Rana; Yano, Junko; Dau, Holger; Kern, Jan; Dobbek, Holger; Zouni, Athina

2017-07-18

In plants, algae and cyanobacteria, Photosystem II (PSII) catalyzes the light-driven splitting of water at a protein-bound Mn 4 CaO 5 -cluster, the water-oxidizing complex (WOC). In the photosynthetic organisms, the light-driven formation of the WOC from dissolved metal ions is a key process because it is essential in both initial activation and continuous repair of PSII. Structural information is required for understanding of this chaperone-free metal-cluster assembly. For the first time, we obtained a structure of PSII from Thermosynechococcus elongatus without the Mn 4 CaO 5 -cluster. Surprisingly, cluster-removal leaves the positions of all coordinating amino acid residues and most nearby water molecules largely unaffected, resulting in a pre-organized ligand shell for kinetically competent and error-free photo-assembly of the Mn 4 CaO 5 -cluster. First experiments initiating (i) partial disassembly and (ii) partial re-assembly after complete depletion of the Mn 4 CaO 5 -cluster agree with a specific bi-manganese cluster, likely a di-µ-oxo bridged pair of Mn(III) ions, as an assembly intermediate.

LA GOBERNACIÓN DE NARIÑO: DEL CAOS TOTAL A LA SOSTENIBILIDAD ADMINISTRATIVA Y FINANCIERA

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Diego Mauricio Díaz Velásquez

2010-07-01

Full Text Available El presente artículo expone el proceso y los resultados que le permitieron a la Gobernación del Departamento de Nariño superar el caos administrativo y financiero que enfrentó a comienzos del siglo veintiuno y obtener la sostenibilidad administrativa y financiera. El caos se generó principalmente por altos niveles de burocratización y una inadecuada administración financiera. Para conseguir el correcto funcionamiento del Departamento de Nariño, el gobierno del 2001 aplicó simultáneamente decisiones administrativas y financieras apoyadas en instrumentos jurídicos con alto impacto económico que lograron contrarrestar el desbalance entre los ingresos y los gastos de la Gobernación, generar racionalización de los procesos administrativos y brindar responsabilidad fiscal a futuro.

Caos, Gea y Eros. Desde el desorden a la armonía de la Paz

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Francisco A. Muñoz

2009-01-01

Full Text Available La cosmogonía griega antigua, al igual que muchas otras, sitúa a Caos como el origen primigenio del Universo. Desde el inicio de los tiempos es acompañada (es femenino por Gea (la Tierra y Eros (el Amor. Con esta explicación se consigue incardinar el Universo, la Tierra, la naturaleza, la vida y los seres humanos con los dioses y las fuerzas sobrenaturales. Eros representaba el deseo que trae la vida, preocupado por conseguir las mejores condiciones para satisfacer las necesidades y procurar el desarrollo de las potencialidades humanas. Desde el comienzo de la historia, para que existiera armonía y paz era necesario gestionar el caos, la complejidad y la conflictividad, y buscar los equilibrios más justos y duraderos posibles.

Synthesis of MgO nanoparticle loaded mesoporous Al2O3 and its defluoridation study

International Nuclear Information System (INIS)

Dayananda, Desagani; Sarva, Venkateswara R.; Prasad, Sivankutty V.; Arunachalam, Jayaraman; Parameswaran, Padmanabhan; Ghosh, Narendra N.

2015-01-01

Highlights: • Simple and cost effective preparation of MgO nanoparticles loaded mesoporous Al 2 O 3 . • Adsorbents possess high surface area and mesoporous structure. • Higher fluoride removal capacity of MgO loaded Al 2 O 3 than that of pure Al 2 O 3 . • Faster fluoride adsorption kinetics of MgO loaded Al 2 O 3 from water. - Abstract: MgO nanoparticle loaded mesoporous alumina has been synthesized using a simple aqueous solution based cost effective method for removal of fluoride from water. Wide angle powder X-ray diffraction, nitrogen adsorption desorption analysis, transmission electron microscopy techniques and energy dispersive X-ray spectroscopy were used to characterize the synthesized adsorbents. Synthesized adsorbents possess high surface area with mesoporous structure. The adsorbents have been thoroughly investigated for the adsorption of F − using batch adsorption method. MgO nanoparticle loading on mesoporous Al 2 O 3 enhances the F − adsorption capacity of Al 2 O 3 from 56% to 90% (initial F − concentration = 10 mg L −1 ). Kinetic study revealed that adsorption kinetics follows the pseudo-second order model, suggesting the chemisorption mechanism. The F − adsorption isotherm data was explained by both Langmuir and Freundlich model. The maximum adsorption capacity of 40MgO@Al 2 O 3 was 37.35 mg g −1 . It was also observed that, when the solutions having F − concentration of 5 mg L −1 and 10 mg L −1 was treated with 40MgO@Al 2 O 3 , the F − concentration in treated water became <1 mg L −1 , which is well below the recommendation of WHO

Electron microscopy and positron annihilation study of CdSe nanoclusters embedded in MgO

International Nuclear Information System (INIS)

Huis, M.A. van; Veen, A. van; Schut, H.; Eijt, S.W.H.; Kooi, B.J.; Hosson, J.Th.M. de

2004-01-01

CdSe nanoclusters are created in MgO by means of co-implantation of 280 keV, 1 x 10 16 Cd ions cm -2 and 210 keV, 1 x 10 16 Se ions cm -2 in single crystals of MgO(0 0 1) and subsequent thermal annealing at a temperature of 1300 K. The structural properties and the orientation relationship between the CdSe and the MgO are investigated using cross-sectional transmission electron microscopy (XTEM). The crystal structure of the nanoclusters depends on their size. The smallest nanoclusters with a size below 5 nm have the cubic rocksalt crystal structure. The larger nanoclusters have a different (most likely the cubic sphalerite) crystal structure. The defect evolution in the sample after ion implantation and during thermal annealing is investigated using Doppler broadening positron beam analysis (PBA). The defect evolution in samples co-implanted with Cd and Se is compared to the defect evolution in samples implanted with only Cd or only Se ions

Preparation of MgO with High Surface Area, and Modification of Its Pore Characteristics

Energy Technology Data Exchange (ETDEWEB)

Lee, Moon Hee; Park, Dong Gon [Sookmyung Women' s University, Seoul (Korea, Republic of)

2003-10-15

Thermal decomposition of hydrated surface layer of Mg(OH){sub 2} at 500 .deg. C in vacuum turned non-porous MgO into porous one with high surface area of around 270 m{sup 2}/g. Most of its surface area, 74 %, was from micropores, and rest of it was from mesopores in wedge-shaped slits, exhibiting bimodal size distribution centered around 30 and 90 A. Rehydration followed by subsequent dehydration at 300 .deg. C in dynamic vacuum further raised the surface area to 340 m{sup 2}/g. Fraction of microporous surface area was increased to 93%, and the shape of the mesopores was modified into parallel slits with a specific dimension of 32 A. Application of Fe{sub 2}O{sub 3} over MgO via iron complex formation did not alter the pore characteristics of MgO core, except slightly increased pore dimension. Over the course of the modification, Fe{sub 2}O{sub 3} stayed on the surface possibly via spill-over reaction.

Electron microscopy and positron annihilation study of CdSe nanoclusters embedded in MgO

Science.gov (United States)

van Huis, M. A.; van Veen, A.; Schut, H.; Eijt, S. W. H.; Kooi, B. J.; De Hosson, J. Th. M.

2004-06-01

CdSe nanoclusters are created in MgO by means of co-implantation of 280 keV, 1 × 10 16 Cd ions cm -2 and 210 keV, 1 × 10 16 Se ions cm -2 in single crystals of MgO(0 0 1) and subsequent thermal annealing at a temperature of 1300 K. The structural properties and the orientation relationship between the CdSe and the MgO are investigated using cross-sectional transmission electron microscopy (XTEM). The crystal structure of the nanoclusters depends on their size. The smallest nanoclusters with a size below 5 nm have the cubic rocksalt crystal structure. The larger nanoclusters have a different (most likely the cubic sphalerite) crystal structure. The defect evolution in the sample after ion implantation and during thermal annealing is investigated using Doppler broadening positron beam analysis (PBA). The defect evolution in samples co-implanted with Cd and Se is compared to the defect evolution in samples implanted with only Cd or only Se ions.

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

Energy Technology Data Exchange (ETDEWEB)

Du, Jiangkun [School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Bao, Jianguo, E-mail: bjianguo@cug.edu.cn [School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Liu, Ying; Ling, Haibo; Zheng, Han [School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Kim, Sang Hoon, E-mail: kim_sh@kist.re.kr [Center for Materials Architecturing, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering, 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States)

2016-12-15

Highlights: Manganese catalyst was immobilized on Fe{sub 3}O{sub 4}/graphene hybrids to facilitate magnetic separation. Magnetic manganese catalyst exhibited high efficacy and long-term stability for catalytic PMS activation. The minerlization efficiency and the biotoxicity of BPA byproducts were evaluated. The degradation pathways of BPA and the possible activation mechanism of PMS were proposed. - Abstract: A heterogeneous manganese/magnetite/graphene oxide (Mn-MGO) hybrid catalyst was fabricated through the reduction of KMnO{sub 4} 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 Mn{sub 2}O{sub 3} to PMS with the generation of sulfate radicals, protons and MnO{sub 2}, as well as the simultaneous reduction of MnO{sub 2} by PMS.

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...

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

Directory of Open Access Journals (Sweden)

Daniela C. Leite Vasconcelos

1999-07-01

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.

Effect of CaO addition on preparation of ferrotitanium from ilmenite by electrochemical reduction in CaCl{sub 2}−NaCl molten salt

Energy Technology Data Exchange (ETDEWEB)

Xiong, Li [Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); State Key Lab of Complex Nonferrous Metal Resources Clean Utilization, Kunming 650093 (China); Hua, Yixin, E-mail: yxhua@kmust.edu.cn [Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); State Key Lab of Complex Nonferrous Metal Resources Clean Utilization, Kunming 650093 (China); Xu, Cunying; Li, Jian; Li, Yan; Zhang, Qibo; Zhou, Zhongren; Zhang, Yadong [Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); State Key Lab of Complex Nonferrous Metal Resources Clean Utilization, Kunming 650093 (China); Ru, Juanjian [Faculty of Material Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

2016-08-15

Ferro-titanium (FeTi) alloy was prepared successfully from synthesized ilmenite through electrochemical reduction method in equal-molar CaCl{sub 2}−NaCl molten salt at 973 K and a cell voltage of 3.2 V under inert atmosphere, where molybdenum rod and graphite were used as cathode and anode respectively. It is indicated that the CaO content in the molten salt has an appreciable effect on the phase transformation of reactants occurring in the electrolytic process. The optimized CaO content in the molten salt is 1 mol% and this suitable content of CaO can significantly improve the reduction rate of ilmenite. The micromorphology of the ferrotitanium product is porous with the amount of 1 mol%CaO addition. It is observed that the particles of ferrotitanium had a uniform size in the initial period of time. Along with the electrolysis time extension, however, the particles connected with each other to generate strips and then form a honeycomb structure. These findings provide a basis for scientifically discussion on the optimization of CaO addition amount during the electrochemical reduction of ilmenite and other oxides in molten salts. - Highlights: • Ferro-titanium was prepared from synthesized ilmenite in CaCl{sub 2}−NaCl molten salt. • CaO content has appreciable effect on the phase transformation of ilmenite reactant. • The optimized CaO content is 1 mol% which can significantly improve reaction rate. • The products are connected with each other to form strips as electrolysis time.

Size Determination of Y2O3 Crystallites in MgO Composite Using Mie Scattering

Science.gov (United States)

2017-11-07

embedded in a magnesium oxide (MgO) polycrystalline matrix. The calculation takes into account the volume fraction of Y2O3 in MgO, the average...release; distribution is unlimited. v Acknowledgments We gratefully acknowledge the financial support from the US Army Research Laboratory (ARL... principle , and the percent of theoretical density (TD) was calculated based on a TD of the mixture being 3.616 g/cm3. Table 1 Sample preparation

Pengaruh Kandungan Ca Pada Cao-zeolit Terhadap Kemampuan Adsorpsi Nitrogen

OpenAIRE

M Nasikin; Tania Surya Utami; Agustina TP Siahaan

2002-01-01

In industry, Ca zeolite is used as nitrogen selective adsorbent with the use of PSA (Pressure Swing Adsorption)/VSA (Vacuum Swing Adsorption) methods. Natural zeolite modified to be Cao-zeolite by ion exchange process using Ca(OH)2. Adsorption test was done on CaO-zeolite with different Ca concentration to understand how it's adsorption phenomena on oxygen and nitrogen. Adsorption test has been done for CaO-zeolite with Ca concentration = 0,682%, 0,849% and 1,244% to oxygen and nitrogen with ...

Study on high temperature desulphurization (Part 1). Comparison of CaO, ZnO, and Fe sub 2 O sub 3 as absorbents at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Yumura, Motoo; Furimsky, E. (National Chemical Lab. for Industry, Tsukuba, (Japan))

1989-06-29

CaO, ZnO, and Fe{sub 2}O{sub 3} were used as adsorbents for H{sub 2}S removal to compare the H{sub 2}S removal and decomposition capacities at high temperature, and their desulphurization characteritics and reaction mechanisms were clarified. Evaluation of H{sub 2}S removal capacity, with the break point used as criterion, showed that increasing the temperature from 600 to 800{sup 0}C increased the H{sub 2}S removal in the presence of CaO but decreased it in the presence of Fe{sub 2}O{sub 3}. For ZnO, the temperature change had little effect on its adsorption. The bulk adsorption capacity was the largest for Fe{sub 2}O{sub 3} followed by CaO and ZnO. When the results were normalized to a unit of surface area, the adsorption capacity for ZnO was the largest followed by Fe{sub 2}O{sub 3} and CaO. In the presence of CaO, adsorption and decomposition started in the early stages while the adsorption of H{sub 2}S was accompanied by its decomposition in the presence of ZnO or Fe{sub 2}O{sub 3}. H{sub 2}S and S are oxidized in the presence of Fe{sub 2}O{sub 3} to produce SO{sub 2}, but no such reaction occurs with CaO or ZnO because it is thermodynamically disadvantageous. 2 refs., 4 figs., 2 tabs.

XRD investigation of the Effect of MgO Additives on ZTA-TiO2 Ceramic Composites

Science.gov (United States)

Azhar, Ahmad Zahirani Ahmad; Manshor, Hanisah; Ali, Afifah Mohd

2018-01-01

Alumina (Al2O3) based ceramics possess good mechanical properties and suitable for the application of cutting inserts. However, this monolithic ceramics suffer from lack of toughness. Hence, there are some modification were made such as the addition of yttria stabilized zirconia (YSZ) to the Al2O3 helps in increasing the toughness of the Al2O3 ceramics. Some additives such as MgO and TiO2 were used to further improve the mechanical properties of ZTA. In this study, high purity raw materials which consist of ZTA-TiO2 were mixed with different amount of MgO (0.0 - 1.0 wt %). The mixture of materials was going through wet mixing, compaction and pressureless sintering at 1600°C for one hour. The samples were characterized for phase analysis, microstructure, shrinkage rate, bulk density, Vickers hardness and fracture toughness. Based on the XRD analysis results, the secondary phase (MgAl2O4) was detected in the sample with 0.5 wt% of MgO onwards which leads to grains refinement, thus improve the density and hardness of ZTA-TiO2-MgO ceramics composites.

Structural characterization of rondorfite, calcium silica chlorine mineral containing magnesium in tetrahedral position [MgO4]6-, with the aid of the vibrational spectroscopies and fluorescence.

Science.gov (United States)

Dulski, M; Bulou, A; Marzec, K M; Galuskin, E V; Wrzalik, R

2013-01-15

Raman and infrared spectra of rondorfite Ca8Mg(SiO4)4Cl2, a calcium chlorosilica mineral containing magnesium in tetrahedral position, has been studied in terms of spectra-structure relations. Raman spectra have been measured at different excited laser lines: 780 nm, 532 nm, 488 nm and 457 nm. This mineral is characterized by a single sharp intense Raman band at 863 cm(-1) assigned to the ν1 [SiO4]4- (Ag) symmetric stretching mode in the magnesiosilicate pentamer. Due to symmetry restriction the other Raman bands have a small intensity. Two Raman bands observed at 564 cm(-1) and 526 cm(-1) are associated simultaneously with ν4 [MgO4]6- and ν4 [SiO4]4- symmetric and antisymmetric modes where magnesium occurs in the tetrahedral configuration. The weak bands at 422 cm(-1) and 386 cm(-1) are associated with the ν2 bending mode of CaO6 in octahedral configuration, respectively. Moreover the infrared spectrum shows very weak bands associated with the hydroxyl group and/or water molecule. Additionally, the strong fluorescence phenomenon was observed and related to the presence of chlorine atoms, magnesium Mg2+ ions in atypical configuration or point defects. Copyright © 2012 Elsevier B.V. All rights reserved.

Epitaxial growth of tungsten layers on MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Zheng, Pengyuan; Ozsdolay, Brian D.; Gall, Daniel, E-mail: galld@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2015-11-15

Smooth single crystal W(001) layers were grown on MgO(001) substrates by magnetron sputtering at 900 °C. X-ray diffraction ω–2θ scans, ω-rocking curves, pole figures, and reciprocal space maps indicate a 45°-rotated epitaxial relationship: (001){sub W}‖(001){sub MgO} and [010]{sub W}‖[110]{sub MgO}, and a relaxed lattice constant of 3.167 ± 0.001 nm. A residual in-plane biaxial compressive strain is primarily attributed to differential thermal contraction after growth and decreases from −0.012 ± 0.001 to −0.001 ± 0.001 with increasing layer thickness d = 4.8–390 nm, suggesting relaxation during cooling by misfit dislocation growth through threading dislocation glide. The in-plane x-ray coherence length increases from 3.4 to 33.6 nm for d = 4.8–390 nm, while the out-of-plane x-ray coherence length is identical to the layer thickness for d ≤ 20 nm, but is smaller than d for d ≥ 49.7 nm, indicating local strain variations along the film growth direction. X-ray reflectivity analyses indicate that the root-mean-square surface roughness increases from 0.50 ± 0.05 to 0.95 ± 0.05 nm for d = 4.8–19.9 nm, suggesting a roughness exponent of 0.38, but remains relatively constant for d > 20 nm with a roughness of 1.00 ± 0.05 nm at d = 47.9 nm.

Theoretical aspects of methyl acetate and methanol activation on MgO(100) and (501) catalyst surfaces with application in FAME production

Energy Technology Data Exchange (ETDEWEB)

Man, Isabela-Costinela, E-mail: isabela.man@g.unibuc.ro [University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, 4-12 Regina Elisabeta Av., S3, 030018 Bucharest (Romania); Romanian Academy, ‘C.D. Nenitzescu’ Center of Organic Chemistry, 202B Spl. Independentei, 060023 Bucharest (Romania); Soriga, Stefan Gabriel [University Politehnica of Bucharest, Centre for Technology Transfer in the Process Industries, 1, Gh. Polizu Street, Building A, Room A056, RO-011061 Bucharest (Romania); Parvulescu, Vasile [University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, 4-12 Regina Elisabeta Av., S3, 030018 Bucharest (Romania)

2017-01-15

Highlights: • Energetics of C−O and C−H bond dissociation and formation of MeOAc on MgO(100) indicate that the bond formations are favorable. • Energetics of C−O and C−H bond dissociation and formation of MeOAc on MgO(501) indicate that the C−O bond dissociation and C−H bond formations are favorable. • The coadsorbed MeOH facilitate O−H bond dissociation of MeOH compared to isolated molecule. • Provide further understanding of reactivity of MgO surfaces with application in transesterification and interesterification reactions. - Abstract: 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 C−O and C−H dissociations and on MgO(501) the same reverse reaction step of C−H dissociations of methyl acetate are energetically favorable, while the dissociation of C−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 O−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

Damage accumulation in MgO irradiated with MeV Au ions at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Bachiller-Perea, Diana, E-mail: dianabachillerperea@gmail.com [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Université Paris-Saclay, 91405, Orsay Cedex (France); Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, C/Faraday 3, 28049, Madrid (Spain); Dpto. de Física Aplicada, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid (Spain); Debelle, Aurélien, E-mail: aurelien.debelle@u-psud.fr [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Université Paris-Saclay, 91405, Orsay Cedex (France); Thomé, Lionel [Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Univ. Paris-Sud, CNRS-IN2P3, Université Paris-Saclay, 91405, Orsay Cedex (France); Behar, Moni [Instituto de Física, Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970, Porto Alegre, RS (Brazil)

2016-09-15

The damage accumulation process in MgO single crystals under medium-energy heavy ion irradiation (1.2 MeV Au) at fluences up to 4 × 10{sup 14} cm{sup −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. - Highlights: • High-temperature MeV-ion irradiated MgO exhibits a two-step damage process. • The occurrence of the second step is delayed with increasing temperature. • The damage level decreases with increasing temperature. • A shift of the damage peak is observed with increasing fluence. • A high defect mobility at high temperatures in MgO is clearly evidenced.

Study of interlayer coupling between FePt and FeCoB thin films through MgO spacer layer

Science.gov (United States)

Singh, Sadhana; Kumar, Dileep; Gupta, Mukul; Reddy, V. Raghvendra

2017-05-01

Interlayer exchange coupling between hard-FePt and soft-FeCoB magnetic layers has been studied with increasing thickness of insulator MgO spacer layer in FePt/MgO/FeCoB sandwiched structure. A series of the samples were prepared in identical condition using ion beam sputtering method and characterized for their magnetic and structural properties using magneto-optical Kerr effect (MOKE) and X-ray reflectivity measurements. The nature of coupling between FePt and FeCoB was found to be ferromagnetic which decreases exponentially with increasing thickness of MgO layer. At very low thickness of MgO layer, both layers were found strongly coupled thus exhibiting coherent magnetization reversal. At higher thickness, both layers were found decoupled and magnetization reversal occurred at different switching fields. Strong coupling at very low thickness is attributed to pin holes in MgO layer which lead to direct coupling whereas on increasing thickness, coupling may arise due to magneto-static interactions.

High-power, continuous-wave, solid-state, single-frequency, tunable source for the ultraviolet.

Science.gov (United States)

Aadhi, A; Apurv Chaitanya, N; Singh, R P; Samanta, G K

2014-06-15

We report the development of a compact, high-power, continuous-wave, single-frequency, ultraviolet (UV) source with extended wavelength tunability. The device is based on single-pass, intracavity, second-harmonic-generation (SHG) of the signal radiation of a singly resonant optical parametric oscillator (SRO) working in the visible and near-IR wavelength range. The SRO is pumped in the green with a 25-mm-long, multigrating, MgO doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) as nonlinear crystal. Using three grating periods, 8.5, 9.0, and 9.5 μm of the MgO:sPPLT crystal and a single set of cavity mirrors, the SRO can be tuned continuously across 710.7-836.3 nm in the signal and corresponding idler across 2115.8-1462.1 nm with maximum idler power of 1.9 W and maximum out-coupled signal power of 254 mW. By frequency-doubling the intracavity signal with a 5-mm-long bismuth borate (BIBO) crystal, we can further tune the SRO continuously over 62.8 nm across 355.4-418.2 nm in the UV with maximum single-frequency UV power, as much as 770 mW at 398.28 nm in a Gaussian beam profile. The UV radiation has an instantaneous line-width of ∼14.5  MHz and peak-peak frequency stability of 151 MHz over 100 s. More than 95% of the tuning range provides UV power >260  mW. Access to lower UV wavelengths can in principle be realized by operating the SRO in the visible using shorter grating periods.

Electron magnetic resonance of diluted solid solutions of Gd{sup 3+} in SrTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Biasi, R.S. de, E-mail: rsbiasi@ime.eb.br [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil); Grillo, M.L.N., E-mail: mluciag@uerj.br [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, 20550-013 Rio de Janeiro, RJ (Brazil)

2011-10-17

Highlights: {yields} EMR is an effective method to study the range of the exchange interaction in solid solutions. {yields} The range of the exchange interaction between Gd{sup 3+} ions in SrTiO{sub 3} is about 0.96 nm. {yields} The linewidth increases faster with Gd concentration in SrTiO{sub 3} than in other host lattices, such as CeO{sub 2}, SrO, CaO and ZrSiO{sub 4}. - Abstract: Electron magnetic resonance (EMR) spectra of gadolinium-doped strontium titanate (SrTiO{sub 3}) have been studied at room temperature for gadolinium concentrations between 0.20 and 1.20 mol%. The results suggest that the Gd{sup 3+} ions occupy substitutional sites, replacing the Sr{sup 2+} ion, that the electron magnetic resonance linewidth increases with increasing gadolinium concentration and that the range of the exchange interaction between Gd{sup 3+} ions is about 0.96 nm, of the same order as that of the same ion in other host lattices, such as ceria (CeO{sub 2}), quicklime (CaO), strontia (SrO) and zircon (ZrSiO{sub 4}). The fact that the electron magnetic resonance linewidth of the Gd{sup 3+} ion increases, regularly and predictably, with Gd concentration, shows that the Gd{sup 3+} ion can be used as a probe to study, rapidly and non-destructively, the crystallinity and degradation of SrTiO{sub 3}.

Computer simulation of oxides

International Nuclear Information System (INIS)

Rowley, A.

1998-01-01

An ionic interaction model is developed which accounts for the effects of the ionic environment upon the electron densities of both cations and anions through changes in their size and shape and is transferable between materials. These variations are represented by additional dynamical variables which are handled within the model using the techniques of the Car-Parrinello method. The model parameters are determined as far as possible by input from external ab initio electronic structure calculations directed at examining the individual effects of the ionic environment upon the ions, particularly the oxide ion. Techniques for the evaluation of dipolar and quadrupolar Ewald sums in non-cubic simulation cells and the calculation of the pressure due to the terms in the potential are presented. This model is applied to the description of the perfect crystal properties and phonon dispersion curves of MgO. Consideration of the high symmetry phonon modes allows parameterization of the remaining model parameters in an unambiguous fashion. The same procedure is used to obtain parameters for CaO. These two parameter sets are examined to determine how they may be used to generate the parameters for SrO and simple scaling relationships based on ionic radii and polarizabilities are formulated. The transferability of the model to Cr 2 O 3 is investigated using parameters generated from the alkaline earth oxides. The importance of lower symmetry model terms, particularly quadrupolar interactions, at the low symmetry ion sites in the crystal structure is demonstrated. The correct ground-state crystal structure is predicted and the calculated surface energies and relaxation phenomena are found to agree well with previous ab initio studies. The model is applied to GeO 2 as a strong test of its applicability to ion environments far different from those encountered in MgO. An good description of the crystal structures is obtained and the interplay of dipolar and quadrupolar effects is

Estimates for diffusion barriers and atomic potentials in MGO

International Nuclear Information System (INIS)

Skala, L.; Kenkre, V.M.

1991-01-01

In this paper, as part of a program of investigation of microwave sintering, self-consistent CNDO/2 calculations are presented for diffusion barriers and potentials for the motion of interstitial atoms and vacancies in MgO. Clusters of 30 atoms are used in the calculations. Activation energies, diffusion barriers, shape of the potentials and electron densities are obtained

Thermically stimulated exoelectronic emissions and thermoluminescence of MgO

International Nuclear Information System (INIS)

Chubaci, J.F.D.

1987-01-01

In this work, studies were performed on the following topics: i) thermically stimulated exoelectronic emission (TSEE) in pure MgO single crystals ion implanted, submitted to thermal treatment with fast on slow cooling and water adsorption; ii) ultraviolet light effect on TSEE; iii) thermoluminescent emission; iv) crystallization of FeCoB amorphous alloys. (A.C.A.S.) [pt

Enhanced bioactivity, biocompatibility and mechanical behavior of strontium substituted bioactive glasses.

Science.gov (United States)

Arepalli, Sampath Kumar; Tripathi, Himanshu; Hira, Sumit Kumar; Manna, Partha Pratim; Pyare, Ram; S P Singh

2016-12-01

Strontium contained biomaterials have been reported as a potential bioactive material for bone regeneration, as it reduces bone resorption and stimulates bone formation. In the present investigation, the bioactive glasses were designed to partially substitute SrO for SiO2 in Na2O-CaO-SrO-P2O5-SiO2 system. This work demonstrates that the substitution of SrO for SiO2 has got significant benefit than substitution for CaO in the bioactive glass. Bioactivity was assessed by the immersion of the samples in simulated body fluid for different intervals. The formation of hydroxy carbonate apatite layer was identified by X-ray diffractometry, scanning electron microscopy (SEM) and energy dispersive spectroscopy. The elastic modulus of the bioactive glasses was measured and found to increase with increasing SrO for SiO2. The blood compatibility of the samples was evaluated. In vitro cell culture studies of the samples were performed using human osteosarcoma U2-OS cell lines and found a significant improvement in cell viability and proliferation. The investigation showed enhancement in bioactivity, mechanical and biological properties of the strontia substituted for silica in glasses. Thus, these bioactive glasses would be highly potential for bone regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

F + centre generation in MgO crystals at high density of excitation by accelerated electrons of subthreshold energy

Science.gov (United States)

Annenkov, Y. M.; Surzhikov, A. P.; Surzhikov, V. P.; Pogrebnjak, A. D.

1981-07-01

Optical absorption spectra and the angular distribution of annihilated positrons in MgO crystals irradiated by subtreshold superdense electron pulses are measured. The experimental results obtained show the effective contribution of the creation mechanism of non-impact radiation defects in MgO crystals at the highest electron irradiation densities.

Phase selection in the containerless solidification of undercooled CaO · 6Al2O3 melts

International Nuclear Information System (INIS)

Li Mingjun; Kuribayashi, Kazuhiko

2004-01-01

The CaO · 6Al 2 O 3 melts were solidified on an aero-acoustic levitator under a containerless processing condition at various undercoolings. A high-speed video was operated to monitor the recalescence behavior, from which the growth velocity as a function of melt undercooling was determined. The microstructures were observed and the crystalline phases were identified using the X-ray diffraction technique, indicting that the Al 2 O 3 was solidified when the melt temperature was higher than the peritectic temperature, T p . When the melt was undercooled below T p , the CaO · 6Al 2 O 3 (CA 6 ) peritectic phase was crystallized directly from the undercooled melts. With respect to the direct formation of the peritectic phase, further analysis from the viewpoints of competitive nucleation indicated that the minimum free energy principle may be applied to elucidate the nucleation of CA 6 phase. In terms of the competitive growth behavior, the interface attachment kinetics for Al 2 O 3 and CA 6 phases are calculated by using the classical BCT model indicating that although the Al 2 O 3 phase doped by CaO has about four times larger interface kinetic coefficient than that of the CA 6 peritectic phase, the growth kinetics of Al 2 O 3 in the melt with the CaO · 6Al 2 O 3 chemical composition is not sufficiently high to replace the CA 6 phase as the primary phase. Therefore, once CA 6 is nucleated, it can develop into a macro crystal as the primary phase. The competitive nucleation and growth behavior in the CA 6 system is different from those in other well-studied peritectic alloys and the present investigation on the phase formation will be an essential supplement to the phase selection theory

A first-principles and experimental study of helium diffusion in periclase MgO

Science.gov (United States)

Song, Zhewen; Wu, Henry; Shu, Shipeng; Krawczynski, Mike; Van Orman, James; Cherniak, Daniele J.; Bruce Watson, E.; Mukhopadhyay, Sujoy; Morgan, Dane

2018-02-01

The distribution of He isotopes is used to trace heterogeneities in the Earth's mantle, and is particularly useful for constraining the length scale of heterogeneity due to the generally rapid diffusivity of helium. However, such an analysis is challenging because He diffusivities are largely unknown in lower mantle phases, which can influence the He profiles in regions that cycle through the lower mantle. With this motivation, we have used first-principles simulations based on density functional theory to study He diffusion in MgO, an important lower mantle phase. We first studied the case of interstitial helium diffusion in perfect MgO and found a migration barrier of 0.73 eV at zero pressure. Then we used the kinetic Monte Carlo method to study the case of substitutional He diffusion in MgO, where we assumed that He diffuses on the cation sublattice through cation vacancies. We also performed experiments on He diffusion at atmospheric pressure using ion implantation and nuclear reaction analysis in both as-received and Ga-doped samples. A comparison between the experimental and simulation results are shown. This work provides a foundation for further studies at high-pressure.

Finančná analýza podniku Choceňská mlékárna, s.r.o.

OpenAIRE

Zigo, Michal

2011-01-01

The bachelor thesis assesses a financial position of the company Choceňská mlékárna, s.r.o. with the help of financial analysis tools such as horizontal and vertical analyses, parallel and pyramidal system of financial ratios, creditworthy and bankruptcy models, and economic value added in the horizon of five years. Theoretical-methodological part describes the financial analysis as a tool for an assessment of the financial position of the company and it further defines the evaluation apparat...

SYNTHESIS OF BIS-QUINOXALINE DERIVATIVES USING TONSIL ...

African Journals Online (AJOL)

A convenient and efficient synthesis of new bis-quinoxaline is described, involving ... the following composition (in %): SiO2: 74.5, Al2O3: 9.3, MgO: 0.4, Fe2O3: 1.3, CaO: 4.0, K2O: 0.4 and .... Tonsil clay is a nanoparticle with layered structure.

Comparative study on the change in index of refraction in ion-exchange interdiffusion in alkali-silicate glasses containing calcium, strontium, barium and titanium oxides

International Nuclear Information System (INIS)

Livshits, V.Ya.; Marchuk, E.A.

1993-01-01

Different ability to ion exchange from the salts of lithium-sodium-silicate glass melt containing calcium (or strontium, or barium) and titanium oxides in addition has been shown. CaO, SrO and BaO have negative effect, but TiO 2 -positive one on the fullness of ion exchange of lithium-sodium and on the rate of interdiffusion in alkali-silicate glass. The value of change in index of refraction of glass with TiO 2 is twice higher than glass with calcium oxide (or strontium, or barium) as the fourth component

Gold atoms and clusters on MgO(100) films; an EPR and IRAS study

Science.gov (United States)

Yulikov, M.; Sterrer, M.; Risse, T.; Freund, H.-J.

2009-06-01

Single gold atoms deposited on single crystalline MgO(1 0 0) films grown on Mo(1 0 0) are characterized by electron paramagnetic resonance spectroscopy as well as IR spectroscopy using CO as probe molecules. In this article we describe the first angular dependent measurements to determine the principal hyperfine components of a secondary hyperfine interaction, namely, with 17O of the MgO. The values determined here are in perfect agreement with theoretical expectations and corroborate the previously reported binding mechanism of Au atoms on the oxygen anions of the MgO terrace. The temperature dependent EPR data reveal an onset of Au atom mobility at about 80 K while the formation of Au particles occurs only above 125 K. By an analysis of the EPR line width in combination with STM measurements it is possible to deduce an increase of the interatomic distance above 80 K. The Au/CO complexes show a somewhat smaller temperature stability as compared to the Au atoms. The observed thermal stability is in perfect agreement with theoretical predictions for CO desorption.

Electron microscopy and positron annihilation study of CdSe nanoclusters embedded in MgO

Energy Technology Data Exchange (ETDEWEB)

Huis, M.A. van E-mail: vanhuis@iri.tudelft.nl; Veen, A. van; Schut, H.; Eijt, S.W.H.; Kooi, B.J.; Hosson, J.Th.M. de

2004-06-01

CdSe nanoclusters are created in MgO by means of co-implantation of 280 keV, 1 x 10{sup 16} Cd ions cm{sup -2} and 210 keV, 1 x 10{sup 16} Se ions cm{sup -2} in single crystals of MgO(0 0 1) and subsequent thermal annealing at a temperature of 1300 K. The structural properties and the orientation relationship between the CdSe and the MgO are investigated using cross-sectional transmission electron microscopy (XTEM). The crystal structure of the nanoclusters depends on their size. The smallest nanoclusters with a size below 5 nm have the cubic rocksalt crystal structure. The larger nanoclusters have a different (most likely the cubic sphalerite) crystal structure. The defect evolution in the sample after ion implantation and during thermal annealing is investigated using Doppler broadening positron beam analysis (PBA). The defect evolution in samples co-implanted with Cd and Se is compared to the defect evolution in samples implanted with only Cd or only Se ions.

The Evaluation of Damage Effects on MgO Added Concrete with Slag Cement Exposed to Calcium Chloride Deicing Salt

Science.gov (United States)

Jang, Jae-Kyeong; Kim, Hong-Gi; Kim, Jun-Hyeong

2018-01-01

Concrete systems exposed to deicers are damaged in physical and chemical ways. In mitigating the damage from CaCl2 deicers, the usage of ground slag cement and MgO are investigated. Ordinary Portland cement (OPC) and slag cement are used in different proportions as the binding material, and MgO in doses of 0%, 5%, 7%, and 10% are added to the systems. After 28 days of water-curing, the specimens are immersed in 30% CaCl2 solution by mass for 180 days. Compressive strength test, carbonation test, chloride penetration test, chloride content test, XRD analysis, and SEM-EDAX analysis are conducted to evaluate the damage effects of the deicing solution. Up to 28 days, plain specimens with increasing MgO show a decrease in compressive strength, an increase in carbonation resistance, and a decrease in chloride penetration resistance, whereas the S30- and S50- specimens show a slight increase in compressive strength, an increase in carbonation resistance, and a slight increase in chloride penetration resistance. After 180 days of immersion in deicing solution, specimens with MgO retain their compressive strength longer and show improved durability. Furthermore, the addition of MgO to concrete systems with slag cement induces the formation of magnesium silicate hydrate (M-S-H) phases. PMID:29758008

The Evaluation of Damage Effects on MgO Added Concrete with Slag Cement Exposed to Calcium Chloride Deicing Salt.

Science.gov (United States)

Jang, Jae-Kyeong; Kim, Hong-Gi; Kim, Jun-Hyeong; Ryou, Jae-Suk

2018-05-14

Concrete systems exposed to deicers are damaged in physical and chemical ways. In mitigating the damage from CaCl₂ deicers, the usage of ground slag cement and MgO are investigated. Ordinary Portland cement (OPC) and slag cement are used in different proportions as the binding material, and MgO in doses of 0%, 5%, 7%, and 10% are added to the systems. After 28 days of water-curing, the specimens are immersed in 30% CaCl₂ solution by mass for 180 days. Compressive strength test, carbonation test, chloride penetration test, chloride content test, XRD analysis, and SEM-EDAX analysis are conducted to evaluate the damage effects of the deicing solution. Up to 28 days, plain specimens with increasing MgO show a decrease in compressive strength, an increase in carbonation resistance, and a decrease in chloride penetration resistance, whereas the S30- and S50- specimens show a slight increase in compressive strength, an increase in carbonation resistance, and a slight increase in chloride penetration resistance. After 180 days of immersion in deicing solution, specimens with MgO retain their compressive strength longer and show improved durability. Furthermore, the addition of MgO to concrete systems with slag cement induces the formation of magnesium silicate hydrate (M-S-H) phases.

Epitaxial growth of bcc-FexCo100-x thin films on MgO(1 1 0) single-crystal substrates

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Nishiyama, Tsutomu; Shikada, Kouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

2010-01-01

Fe x Co 100-x (x=100, 65, 50 at%) epitaxial thin films were prepared on MgO(1 1 0) single-crystal substrates heated at 300 deg. C by ultra-high vacuum molecular beam epitaxy. The film structure and the growth mechanism are discussed. FeCo(2 1 1) films with bcc structure grow epitaxially on MgO(1 1 0) substrates with two types of variants whose orientations are rotated around the film normal by 180 deg. each other for all compositions. Fe x Co 100-x film growth follows the Volmer Weber mode. X-ray diffraction analysis indicates the out-of-plane and the in-plane lattice spacings are in agreement with the values of respective bulk Fe x Co 100-x crystals with very small errors less than ±0.4%, suggesting the strains in the films are very small. High-resolution cross-sectional transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the film at the Fe 50 Co 50 /MgO interface along the MgO[1 1-bar 0] direction. The presence of such periodical dislocations decreases the large lattice mismatch of about -17% existing at the FeCo/MgO interface along the MgO[1 1-bar 0] direction.

Comparison of interface structure of BCC metallic (Fe, V and Nb) films on MgO (100) substrate

Energy Technology Data Exchange (ETDEWEB)

Du, J.L. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Zhang, L.Y. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Fu, E.G., E-mail: efu@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Ding, X., E-mail: dingxd@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Yu, K.Y., E-mail: kyyu@cup.edu.cn [Department of Materials Science and Engineering, China University of Petroleum, Beijing 102249 (China); Wang, Y.G. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Wang, Y.Q.; Baldwin, J.K. [Experimental Physical Sciences Directorate, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Wang, X.J. [State Key Laboratory of Advanced Optical Communication Systems and Networks, Peking University, Beijing 100871 (China); Xu, P. [Department of Chemistry, Harbin Institute of Technology, Harbin, Heilongjiang, 150001 (China)

2017-07-15

Highlights: • The difference of BCC metal/MgO(100) interface configuration with various lattice mismatches is identified by experiments and simulations in terms of dislocations and work of separation. • The strength of bonds along interface is found to be the fundamental factor to determine the interface configurations between BCC metal and MgO substrate. • The combination of experiments and simulations shows that the O-atop model is the actual match type between BCC metal and MgO substrate. - Abstract: This study systematically investigates the interface structure of three body-centered-cubic (BCC) metallic (Fe, V and Nb) films grown on MgO(100) substrates through experiments and simulations. Orientation relationships of their interfaces with the different lattice mismatches exhibit cube-on-cube configurations. The misfit dislocations at these three interfaces exhibit different characteristics. High resolution TEM (HRTEM), combined with first principle calculations, demonstrates the O-atop match type between metal atoms and MgO substrates for the first time. The fundamental mechanism in determining the interface configuration is discussed in terms of the work of separation and delocalization of atomic charge density.

External electric field driven modification of the anomalous and spin Hall conductivities in Fe thin films on MgO(001)

Science.gov (United States)

Pradipto, Abdul-Muizz; Akiyama, Toru; Ito, Tomonori; Nakamura, Kohji

2018-01-01

The effects of applying external electric fields to the anomalous and spin Hall conductivities in Fe thin-film models with different layer thicknesses on MgO(001) are investigated by using first-principles calculations. We observe that, for the considered systems, the application of positive electric field associated with the accumulation of negative charges on the Fe side generally decreases (increases) the anomalous (spin) Hall conductivities. The mapping of the Hall conductivities within the two-dimensional Brillouin zone shows that the electric-field-induced modifications are related to the modification of the band structures of the atoms at the interface with the MgO substrate. In particular, the external electric field affects the Hall conductivities via the modifications of the dx z,dy z orbitals, in which the application of positive electric field pushes the minority-spin states of the dx z,dy z bands closer to the Fermi level. Better agreement with the anomalous Hall conductivity for bulk Fe and a more realistic scenario for the electric field modification of Hall conductivities are obtained by using the thicker layers of Fe on MgO (Fe3/MgO and Fe5/MgO).

Neutron monochromators of BeO, MgO and ZnO single crystals

Science.gov (United States)

Adib, M.; Habib, N.; Bashter, I. I.; Morcos, H. N.; El-Mesiry, M. S.; Mansy, M. S.

2014-05-01

The monochromatic features of BeO, MgO and ZnO single crystals are discussed in terms of orientation, mosaic spread, and thickness within the wavelength band from 0.05 up to 0.5 nm. A computer program MONO, written in “FORTRAN”, has been developed to carry out the required calculations. Calculation shows that a 5 mm thick MgO single crystal cut along its (2 0 0) plane having mosaic spread of 0.5° FWHM has the optimum parameters when it is used as a neutron monochromator. Moreover, at wavelengths shorter than 0.24 nm the reflected monochromatic neutrons are almost free from the higher order ones. The same features are seen with BeO (0 0 2) with less reflectivity than that of the former. Also, ZnO cut along its (0 0 2) plane is preferred over the others only at wavelengths longer than 0.20 nm. When the selected monochromatic wavelength is longer than 0.24 nm, the neutron intensities of higher orders from a thermal reactor flux are higher than those of the first-order one. For a cold reactor flux, the first order of BeO and MgO single crystals is free from the higher orders up to 0.4 nm, and ZnO at wavelengths up to 0.5 nm.

Quantification of MgO surface excess on the SnO2 nanoparticles and relationship with nanostability and growth

International Nuclear Information System (INIS)

Gouvea, Douglas; Pereira, Gilberto J.; Gengembre, Leon; Steil, Marlu C.; Roussel, Pascal; Rubbens, Annick; Hidalgo, Pilar; Castro, Ricardo H.R.

2011-01-01

In this work, we experimentally showed that the spontaneous segregation of MgO as surface excess in MgO doped SnO 2 nanoparticles plays an important role in the system's energetics and stability. Using X-ray fluorescence in specially treated samples, we quantitatively determined the fraction of MgO forming surface excess when doping SnO 2 with several different concentrations and established a relationship between this amount and the surface energy of the nanoparticles using the Gibbs approach. We concluded that the amount of Mg ions on the surface was directly related to the nanoparticles total free energy, in a sense that the dopant will always spontaneously distribute itself to minimize it if enough diffusion is provided. Because we were dealing with nanosized particles, the effect of MgO on the surface was particularly important and has a direct effect on the equilibrium particle size (nanoparticle stability), such that the lower the surface energy is, the smaller the particle sizes are, evidencing and quantifying the thermodynamic basis of using additives to control SnO 2 nanoparticles stability.

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

2016-12-01

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.

Hydroxyapatite and zirconia composites: Effect of MgO and MgF2 on the stability of phases and sinterability

International Nuclear Information System (INIS)

Evis, Zafer; Usta, Metin; Kutbay, Isil

2008-01-01

Composites of hydroxyapatite with cubic zirconia with MgO or MgF 2 were pressureless sintered at temperatures from 1000 to 1300 deg. C. The reactions and transformations of phases were monitored with X-ray diffraction. For the hydroxyapatite and zirconia composites with MgO, calcium diffused from hydroxyapatite into the zirconia, and hydroxyapatite decomposed to tri-calcium phosphate at sintering temperatures higher than 1000 deg. C. Above about 1200 deg. C, CaZrO 3 was formed. Composites containing the MgF 2 decomposed slower than the composites with MgO which was verified by the changes in the lattice volume of the hydroxyapatite left in the composites. Fluorine ions in MgF 2 diffused into hydroxyapatite which resulted in thermal stability at high sintering temperatures. Composites with MgF 2 had higher hardness than those with MgO. The lowest porosity was found in a composite initially containing 10 wt% cubic zirconia and 5 wt% MgF 2

Bitumen extraction from oil sands ore-water slurry using CaO (lime) and or ozone

Energy Technology Data Exchange (ETDEWEB)

Babadagli, T. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Alberta Univ., Edmonton, AB (Canada); Burkus, Z.; Moschopedis, S.E.; Ozum, B. [Apex Engineering Inc., Calvert City, KY (United States)

2008-10-15

Reductions in the surface and interfacial tensions in oil sands ore-water slurry systems improve bitumen extraction processes from oil sands ore structures and promote the attachment of air bubbles to liberated bitumen droplets. This study provided details of a non-caustic bitumen extraction process where oil sands slurries were conditioned by bitumen asphaltenes modified to act as surfactants. Oil sands ore-water slurry extraction processes were optimized by adding lime (CaO) and oxidizing bitumen asphaltenes with ozone (O{sub 3}). Experiments were conducted using oil sands ore and process water samples from Alberta. Extraction tests were performed to investigate the effects of various CaO and O{sub 3} dosages and treatment retention times on bitumen extraction efficiency on operating temperatures of 20, 35 and 50 degrees C. A Dean-Stark extraction apparatus was used to determine the amount of bitumen contained in the ore, froth, and in left-over tailings. Process water and release water chemistry were also monitored. Bitumen extraction efficiency was defined as the percentage of bitumen recovered in the resulting froth. Use of the slurries allowed high extraction efficiencies at a temperature of 35 degrees C. Energy consumption and carbon dioxide (CO{sub 2}) emissions were also reduced. The study showed that both additions resulted in significant improvements in bitumen extraction efficiency. Use of the technique also eliminated the accumulation of Na{sup +} ions in produced water. It was concluded that further tests are needed in order to commercialize the CaO and O{sub 3} based techniques. 14 refs., 1 tab., 4 figs.

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.

Superconducting tunnel junctions on MgB{sub 2} using MgO and CaF{sub 2} as a barrier

Energy Technology Data Exchange (ETDEWEB)

Sakoda, Masahito, E-mail: sakoda@cc.tuat.ac.jp [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16, Koganei, Tokyo 184-8588 (Japan); Aibara, Masato; Mede, Kazuya; Kikuchi, Motoyuki; Naito, Michio [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16, Koganei, Tokyo 184-8588 (Japan)

2016-11-15

Highlights: • We have revised the manuscript according to reviewer's comments. The details are in “Response to Reviewers”. • Superconducting junctions with MgO and CaF{sub 2} barrier were fabricated in order to improve the quality of junctions. • In SIN junctions with MgO barrier, clear superconducting gap was observed. (). • In SIS junctions with CaF2 barrier, Josephson current was observed over 30 K. (). • The compatibility of each barrier material at the upper and lower interfaces was clarified. (). - Abstract: We report the fabrication of superconducting tunnel junctions, both of superconductor–insulator-normal metal (SIN) and superconductor–insulator-superconductor (SIS), on MgB{sub 2} using MgO and CaF{sub 2} as a barrier. The SIN junctions fabricated using an MgO barrier showed excellent quasi-particle characteristics, including a large superconducting gap (Δ) of 2.5–3 meV and a low zero-bias conductance. We have also fabricated SIS junctions with an MgO barrier, but the quasi-particle characteristics of the SIS junctions are not as good as those of the SIN junctions, namely a reduced superconducting gap and a high zero-bias conductance. It appears that top MgB{sub 2} electrodes do not grow well on an MgO barrier, which is also suggested from in-situ RHEED observation. The SIN junctions fabricated using a CaF{sub 2} barrier showed less sharp quasi-particle characteristics than using an MgO barrier. However, the SIS junctions using a CaF{sub 2} barrier showed a fairly large I{sub c}R{sub N} value at 4.2 K over 1 mV and also exhibited finite Josephson current up to almost the film's T{sub c} (∼30 K). The RHEED observation revealed that top MgB{sub 2} electrodes grow well on a CaF{sub 2} barrier.

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.

methanes using Expanded Perlite-PPA as a heterogeneous solid

Indian Academy of Sciences (India)

or more of the following disadvantages such as high to- xicity, high cost .... Constituent. SiO2. Al2O3. K2O. Fe2O3. Na2O. CaO. MgO. Percentage. 75.22. 12.77. 5.18. 0.74 ...... I and Savvidis T 2006 Influence of thermal treatment on the water ...

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

The low energy tails of the ultra-violet cut-off were found to obey Urbach's rule in the optical range 360–500 nm. ... wavelengths maxima towards longer wavelength in titania introduced silicate glasses was observed on replacement of MgO by CaO which may be attributed due to an increase in basicity of the glass system.

Ion beam synthesis of Fe nanoparticles in MgO and yttria-stabilized zirconia

Science.gov (United States)

Potzger, K.; Reuther, H.; Zhou, Shengqiang; Mücklich, A.; Grötzschel, R.; Eichhorn, F.; Liedke, M. O.; Fassbender, J.; Lichte, H.; Lenk, A.

2006-04-01

To form embedded Fe nanoparticles, MgO(001) and YSZ(001) single crystals have been implanted at elevated temperatures with Fe ions at energies of 100 keV and 110 keV, respectively. The ion fluence was fixed at 6×1016 cm-2. As a result, γ- and α-phase Fe nanoparticles were synthesized inside MgO and YSZ, respectively. A synthesis efficiency of 100% has been achieved for implantation at 1273 K into YSZ. The ferromagnetic behavior of the α-Fe nanoparticles is reflected by a magnetic hyperfine field of 330 kOe and a hysteretic magnetization reversal. Electron holography showed a fringing magnetic field around some, but not all of the particles.

Ion beam synthesis of Fe nanoparticles in MgO and yttria-stabilized zirconia

International Nuclear Information System (INIS)

Potzger, K.; Reuther, H.; Zhou, Shengqiang; Muecklich, A.; Groetzschel, R.; Eichhorn, F.; Liedke, M. O.; Fassbender, J.; Lichte, H.; Lenk, A.

2006-01-01

To form embedded Fe nanoparticles, MgO(001) and YSZ(001) single crystals have been implanted at elevated temperatures with Fe ions at energies of 100 keV and 110 keV, respectively. The ion fluence was fixed at 6x10 16 cm -2 . As a result, γ- and α-phase Fe nanoparticles were synthesized inside MgO and YSZ, respectively. A synthesis efficiency of 100% has been achieved for implantation at 1273 K into YSZ. The ferromagnetic behavior of the α-Fe nanoparticles is reflected by a magnetic hyperfine field of 330 kOe and a hysteretic magnetization reversal. Electron holography showed a fringing magnetic field around some, but not all of the particles

The Melting Curve and Premelting of MgO

OpenAIRE

Cohen, R. E.; Weitz, J. S.

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 $\\Delta V_m$ and integrating the Clapeyro...

Sustainable biodiesel production via transesterification of waste cooking oil by using CaO catalysts prepared from chicken manure

International Nuclear Information System (INIS)

Maneerung, Thawatchai; Kawi, Sibudjing; Dai, Yanjun; Wang, Chi-Hwa

2016-01-01

Highlights: • Calcined chicken manure was successfully used as catalyst for biodiesel production. • Ca compound in chicken manure was converted into active CaO by calcination. • Chicken manure-derived catalysts show high activity towards transesterification. • Biodiesel fuels can be produced by using waste cooking oils. - Abstract: The low cost and efficient CaO catalysts have been successfully prepared from chicken manure by a simple calcination, in this present work. Chicken manure contains significant content of calcium compounds that can easily be converted into the active calcium oxide catalyst after calcination at 850 °C under air. The Hammett indicator test showed that the obtained CaO catalyst has the basic strength in a range of 15 < H- < 18.4, revealing that the basicity of the obtained catalyst is mainly ascribed to the strong basic properties of metal–O groups. The obtained CaO catalyst exhibited high catalytic activity for biodiesel production from transesterification of waste cooking oil and methanol. Up to 90% FAME yield was obtained at optimum reaction condition (i.e. 7.5 wt% of catalyst, 15:1 of methanol:oil molar ratio and 65 °C). The experimental kinetic data fitted well with the pseudo-first order model and the activation energy was found to be 78.8 kJ mol"−"1. Moreover, fuel properties of the produced biodiesel were determined according to the European standard and found to be within the specifications. The uses of chicken manure as a catalyst source and waste cooking oil as a raw material for biodiesel production not only offers the environmentally friendly and cost-effective way to recycle those wastes, but also help to lower the biodiesel production cost to make biodiesel competitive with petroleum-based diesel.

SeO2 adsorption on CaO surface: DFT and experimental study on the adsorption of multiple SeO2 molecules

Science.gov (United States)

Fan, Yaming; Zhuo, Yuqun; Li, Liangliang

2017-10-01

SeO2 adsorption mechanisms on CaO surface were firstly investigated by both density functional theory (DFT) calculations and adsorption experiments. Adsorption of multiple SeO2 on the CaO (001) surface was investigated using slab model. Based on the results of adsorption energy and surface property, a double-layer adsorption mechanisms were proposed. In experiments, the SeO2 adsorption products were prepared in a U-shaped quartz reactor at 200 °C. The surface morphology was investigated by field emission scanning electron microscopy (FE-SEM). The superficial and total SeO2 mass fractions were measured by X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), respectively. The surface valence state and bulk structure are determined by XPS and X-Ray Diffraction (XRD). The experimental results are in good agreement with the DFT results. In conclusion, the fundamental SeO2 chemisorption mechanisms on CaO surface were suggested.

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.

Perpendicular magnetic tunnel junction with tunneling magnetoresistance ratio of 64% using MgO (100) barrier layer prepared at room temperature

International Nuclear Information System (INIS)

Ohmori, Hideto; Hatori, Tomoya; Nakagawa, Shigeki

2008-01-01

MgO (100) textured films can be prepared by reactive facing targets sputtering at room temperature without postdeposition annealing process when they were deposited on (100) oriented Fe buffer layers. This method allows fabrication of perpendicular magnetic tunnel junction (p-MTJ) with MgO (100) tunneling barrier layer and rare-earth transition metal (RE-TM) alloy thin films as perpendicularly magnetized free and pinned layers. The 3-nm-thick MgO tunneling barrier layer in p-MTJ multilayer prepared on glass substrate revealed (100) crystalline orientation. Extraordinary Hall effect measurement clarified that the perpendicular magnetic components of 3-nm-thick Fe buffer layers on the two ends of MgO tunneling barrier layer were increased by exchange coupling with RE-TM alloy layers. The RA of 35 kΩ μm 2 and tunneling magnetoresistance ratio of 64% was observed in the multilayered p-MTJ element by current-in-plane-tunneling

“El carácter total del mundo” Esbozo de una ontología del caos en Nietzsche

Directory of Open Access Journals (Sweden)

Luis Eduardo Gama

2017-01-01

Full Text Available Largamente desatendida o malinterpretada, la noción de caos en la filosofía de Nietzsche es una pieza constitutiva de la particular concepción del ser que este autor habría dejado apenas esbozada. El artículo se propone elaborar este concepto en la obra nietzscheana, siguiendo algunas de las metáforas que lo iluminan (las estrellas, el texto y el mundo. Desde allí se busca plantear los rasgos centrales de una ontologia del caos, de sesgo no metafísico, que, al afirmar el carácter acontecimental de la realidad, puede verse como precursora de la ontología hermenéutica contemporánea.

Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

International Nuclear Information System (INIS)

Belmeguenai, M.; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P.; Gabor, M. S.; Petrisor, T.; Tiusan, C.

2014-01-01

10 nm and 50 nm Co 2 FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T a ), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T a , while the uniaxial anisotropy field is nearly unaffected by T a within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T a . Finally, the FMR linewidth decreases when increasing T a , due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10 −3 and 1.3×10 −3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

Preparation and characterization of Ti-doped MgO nanopowders by a modified coprecipitation method

International Nuclear Information System (INIS)

Wang Wei; Qiao Xueliang; Chen Jianguo; Tan Fatang

2008-01-01

Ti-doped MgO nanopowders were prepared via a chemical coprecipitation method using acetic acid as a modifier in the presence of the surfactant polyethylene glycol (PEG 400). The as-obtained products were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), differential thermal analysis (DTA) and transmission electron microscopy (TEM). The results show that titanium atoms have been successfully incorporated into the crystal lattice of MgO with periclase structure. The modifier, acetic acid, can significantly reduce the particle size, and improve size distribution and dispersion of nanoparticles. In addition, the effect of doped titanium on the structure and morphology of magnesium oxide was also investigated

Growth, structure and magnetic properties of FePt nanostructures on NaCl(001) and MgO(001)

International Nuclear Information System (INIS)

Liscio, F; Maret, M; Doisneau-Cottignies, B; Makarov, D; Albrecht, M; Roussel, H

2010-01-01

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 L1 0 chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L1 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 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.

Effect of hot extrusion, other constituents, and temperature on the strength and fracture of polycrystalline MgO

Energy Technology Data Exchange (ETDEWEB)

Rice, R.W. (W.R. Grace and Co.-Conn, Columbia, MD (United States))

1993-12-01

Improved agreement was confirmed between the Petch intercept and single-crystal yield stresses at 22 C. Hot-extruded MgO crystal specimens stressed parallel with the resultant axial texture (1) gave the highest and least-scattered strength-grain size results at 22 C, (2) showed direct fractographic evidence of microplastic initiated fracture at 22 C and showed macroscopic yield at 1,315 and especially 1,540 C, and (3) fractured entirely via transgranular cleavage, except for intergranular failure initiation from one or a few grain boundary surfaces exposed on the subsequent fracture surface, mainly at 1,540 C. Hot-extruded, hot-pressed MgO billets gave comparable strength when fracture initiated transgranularly, but lower strength when fracture initiated from one or especially a few grain boundary surfaces exposed on the fracture. The extent and frequency of such boundary fracture increased with test temperature. While oxide additions of [<=] 5% or impurities in hot-pressed or hot-extruded MgO can make limited strength increases at larger grain sizes, those having limited solubility can limit strength at finer grain sizes, as can coarser surface finish. Overall, MgO strength is seen as a balance between flaw and microplastic controlled failure, with several parameters shifting the balance.

Využítí sociálních sítí v praxi firmy "business communication s.r.o."

OpenAIRE

Švojgrová, Anna

2013-01-01

This thesis is an analysis of the internal and extrenal communication of a small IT company business communication s.r.o. with emphasis on social media. The theoretical part of this paper deals with the use of social networks by individuals and companies in the Czech Republic and abroad. The practical part introduces the reader into the company business communication and its business practise, analyses its current internal and external communication, especially via social networks, and identi...

Annealing temperature effects on the magnetic properties and induced defects in C/N/O implanted MgO

Science.gov (United States)

Li, Qiang; Ye, Bonian; Hao, Yingping; Liu, Jiandang; Kong, Wei; Ye, Bangjiao

2013-02-01

Virgin MgO single crystals were implanted with 70 keV C/N/O ions at room temperature to a dose of 2 × 1017/cm2. After implantation the samples showed room temperature hysteresis in magnetization loops. The annealing effects on the magnetic properties and induced defects of these samples were determined by vibrating sample magnetometer and positron annihilation spectroscopy, respectively. The experimental results indicate that ferromagnetism can be introduced to MgO single crystals by doping with C, N or introduction of Mg related vacancy defects. However, the Mg vacancies coexistence with C or N ions in the C-/N-implanted samples may play a negative role in magnetic performance in these MgO samples. The rapid increase of magnetic moment in O-implanted sample is attributed to the formation of new type of vacancy defects.

Positronium deuteride and hydride in MgO crystals

OpenAIRE

Monge, M. A.; Pareja, R.; González, R.; Chen, Y.

1996-01-01

Low-temperature positron lifetime and Doppler broadening measurements were made in MgO crystals containing D− or H− ions in order to investigate the temperature dependence of the positron trapping by D− and H− ions and elucidate the possible formation of PsD (PsH) states. Positrons are trapped at D− and H− ions once the oxygen vacancies, which are more effective positron traps, are eliminated by annealing the crystals at high temperatures in a reducing atmosphere. From the temperature depende...

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.

CaO Nanocatalyst for Transesterification Reaction of Palm Oil to Biodiesel: Effect of Precursor’s Concentration on the Catalyst Behavior

Science.gov (United States)

Hassan, N.; Ismail, K. N.; Hamid, K. H. Ku; Hadi, Abdul

2018-05-01

Depletion of fossil fuel sources in a few decades due to industrialization and motorization has led to a keen interest in the production of alternative fuels like biodiesel. Research on the development and improvement of more efficient transesterification process for biodiesel production has attain great attention in the last decade. The using of low cost catalyst is one of the main focuses on the biodiesel production. As a basic heterogeneous catalyst, CaO has been examined in the transesterification of vegetable oils for biodiesel production. In this research, calcium oxide (CaO-X) catalysts were prepared by sol-gel method at different Ca2+ precursor concentration (X = 1.0, 1.5, 2.0 M). The crystalline structure and morphology of the synthesized catalysts were characterized by means of x-ray diffraction (XRD) and N2 adsorption-desorption analysis. All the synthesized catalysts were then applied to transesterification reaction of palm oil to produce biodiesel. The characterization by x-ray diffraction demonstrate CaO-1.0 was partially hydrated due to the incomplete reaction during synthesis. As a matter of fact, formation of H2O on the surface of CaO causes lower basic strength of the catalysts, thus responsible in lowering the catalytic activity. It is demonstrated that CaO-2.0 exhibits mesoporous structure with least chemisorb amount of H2O on the catalysts surface has a very active catalytic activity. It was found that 2.0M of calcium precursor has high catalytic activity and 81% FAME yield was obtained within 3h reaction.

Positron annihilation study of formation of Mg vacancy in MgO

International Nuclear Information System (INIS)

Mizuno, M.; Araki, H.; Shirai, Y.; Inoue, Y.; Sugita, K.; Mizoguchi, T.; Tanaka, I.; Adachi, H.

2004-01-01

We have investigated the formation of Mg vacancy induced by ultra-dilute trivalent impurities in MgO by a combination of positron annihilation measurement and theoretical calculations of positron lifetimes. The undoped MgO yields the shortest positron lifetime of 130 ps that is shorter than that of 166 ps previously reported using a single crystal sample. The positron lifetime of the doped samples increases with the increase of the Al or Ga dopant concentration and is saturated at around 170 ps. This result indicates that the previously reported value of 166 ps is ascribed to not the bulk but the vacancy state induced by impurities. The experimental bulk lifetime of 130 ps, which is obtained by employing trapping model, is well reproduced by the theoretical calculation using the semiconductor model. The calculated defect lifetime is about 20 ps longer than the experimental value. This may be due to the lattice relaxation around Mg vacancy associated with the trapping of positrons. (orig.)

Positron annihilation study of formation of Mg vacancy in MgO

Energy Technology Data Exchange (ETDEWEB)

Mizuno, M.; Araki, H.; Shirai, Y. [Science and Technology Center for Atoms, Molecules and Ions Control, Osaka Univ., Osaka (Japan); Inoue, Y.; Sugita, K. [Dept. of Materials Science and Engineering, Osaka Univ., Osaka (Japan); Mizoguchi, T.; Tanaka, I.; Adachi, H. [Dept. of Materials Science and Engineering, Kyoto Univ., Kyoto (Japan)

2004-07-01

We have investigated the formation of Mg vacancy induced by ultra-dilute trivalent impurities in MgO by a combination of positron annihilation measurement and theoretical calculations of positron lifetimes. The undoped MgO yields the shortest positron lifetime of 130 ps that is shorter than that of 166 ps previously reported using a single crystal sample. The positron lifetime of the doped samples increases with the increase of the Al or Ga dopant concentration and is saturated at around 170 ps. This result indicates that the previously reported value of 166 ps is ascribed to not the bulk but the vacancy state induced by impurities. The experimental bulk lifetime of 130 ps, which is obtained by employing trapping model, is well reproduced by the theoretical calculation using the semiconductor model. The calculated defect lifetime is about 20 ps longer than the experimental value. This may be due to the lattice relaxation around Mg vacancy associated with the trapping of positrons. (orig.)

Porous rod-like MgO complex membrane with good anti-bacterial activity directed by conjugated linolenic acid polymer

Energy Technology Data Exchange (ETDEWEB)

Wang, Hua-Jie, E-mail: wanghuajie972001@163.com; Chen, Meng [Henan Normal University, College of Chemistry and Chemical Engineering (China); Mi, Li-Wei, E-mail: mlwzzu@163.com [Zhongyuan University of Technology, Center for Advanced Materials Research (China); Shi, Li-Hua [Anyang 101 Education Center (China); Cao, Ying, E-mail: caoying1130@sina.com [Zhongyuan University of Technology, Center for Advanced Materials Research (China)

2016-02-15

The problem of infection in the tissue engineering substitutes is driving us to seek new coating materials. We previously found that conjugated linolenic acid (CLnA) has well biocompatibility and excellent membrane-forming property. The objective of this study is to endow the anti-bacterial activity to CLnA membra ne by linking with MgO. The results showed that the CLnA polymer membrane can be loaded with porous rod-like MgO and such complex membrane showed anti-bacterial sensitivity against gram-positive bacteria (Staphylococcus aureus) even at the low concentration (0.15 μg/mm{sup 2}). In the present study, the best zone of inhibition got to 18.2 ± 0.8 mm when the amount of MgO reach 2.42 ± 0.58 μg/mm{sup 2}. It was deduced that the porous rod-like structure of MgO was directed by CLnA in its polymerization process. Such CLnA/MgO complex membrane can be helpful in the tissue engineering, medicine, food engineering, food preservation, etc. on the basis of its good anti-bacterial activity.

Influence of high-temperature steam on the reactivity of CaO sorbent for CO₂ capture.

Science.gov (United States)

Donat, Felix; Florin, Nicholas H; Anthony, Edward J; Fennell, Paul S

2012-01-17

Calcium looping is a high-temperature CO(2) capture technology applicable to the postcombustion capture of CO(2) from power station flue gas, or integrated with fuel conversion in precombustion CO(2) capture schemes. The capture technology uses solid CaO sorbent derived from natural limestone and takes advantage of the reversible reaction between CaO and CO(2) to form CaCO(3); that is, to achieve the separation of CO(2) from flue or fuel gas, and produce a pure stream of CO(2) suitable for geological storage. An important characteristic of the sorbent, affecting the cost-efficiency of this technology, is the decay in reactivity of the sorbent over multiple CO(2) capture-and-release cycles. This work reports on the influence of high-temperature steam, which will be present in flue (about 5-10%) and fuel (∼20%) gases, on the reactivity of CaO sorbent derived from four natural limestones. A significant increase in the reactivity of these sorbents was found for 30 cycles in the presence of steam (from 1-20%). Steam influences the sorbent reactivity in two ways. Steam present during calcination promotes sintering that produces a sorbent morphology with most of the pore volume associated with larger pores of ∼50 nm in diameter, and which appears to be relatively more stable than the pore structure that evolves when no steam is present. The presence of steam during carbonation reduces the diffusion resistance during carbonation. We observed a synergistic effect, i.e., the highest reactivity was observed when steam was present for both calcination and carbonation.

Optical studies of E-beam evaporated MgO films for plasma display panels

CERN Document Server

Lee, S I; Oh, S G

1999-01-01

Variable-incident-angle spectroscopic ellipsometry has been used for non-destructive depth profiling of MgO thin films, one of the key elements of plasma display panels. We have found that all the examined MgO films have a three-layer structure with a dense interface layer , a void-included middle layer, and a surface layer. We have also found that the void fraction is increased with the oxygen-flow rate at a fixed substrate temperature and decreased with the substrate temperature at a fixed oxygen-flow rate. Moreover, discuss the close correlation between the water adsorption and the void fraction and show a general agreement between the surface layer thickness and the mean height determined by using a atomic force microscopy.

MgO by injection CVD

International Nuclear Information System (INIS)

Abrutis, A.; Kubilius, V.; Teiserkis, A.; Bigelyte, V.; Vengalis, B.; Jukna, A.; Butkute, R.

1997-01-01

Epitaxial YBa 2 Cu 3 O 7 layers with 45 in-plane orientation have been grown by injection CVD on MgO substrates polished off-axis to within 1.4-1.9 of the [100] direction. This new single-source CVD process is based on computer-controlled injection of precise microdoses of a metal-organic precursor solution into a CVD reactor. A wide range of solution compositions was tested to investigate compositional effects on phase purity, surface morphology, texturing and superconducting properties of the prepared films. The highest quality films with pure 45 texture had a smooth surface, zero resistance T c (R=0) of 88-89 K, and critical current density J c (77 K) above 10 6 A/cm 2 . (orig.) and critical current density J c (77 K) above 10 6 A/cm 2 . (orig.)

Development of a high temperature ceramic-to-metal seal for Air Force Weapons Laboratory Laser

Science.gov (United States)

Honnell, R. E.; Stoddard, S. D.

1987-03-01

Procedures were developed for fabricating vacuum tight metal-to-ceramic ring seals between Inconel 625 and MgO-3 wt % Y2O3 tubes metallized with a calcia-alumina-silica glass (CaO-29 wt % Al2O3-35 wt % SiO2) containing 50 vol % molybdenum filler. Palniro No. 1 (Au-25 wt % Pd-25 wt % Ni) was found to be the most reliable braze for joining Inconel to metallized MgO-3 wt % Y2O3 bodies. The reliabilities of the processing procedures and the material systems were demonstrated. A prototype electrical feedthrough was fabricated for 1173 K operation in air or vacuum.

Experimental and Statistical Analysis of MgO Nanofluids for Thermal Enhancement in a Novel Flat Plate Heat Pipes

Science.gov (United States)

Pandiaraj, P.; Gnanavelbabu, A.; Saravanan, P.

Metallic fluids like CuO, Al2O3, ZnO, SiO2 and TiO2 nanofluids were widely used for the development of working fluids in flat plate heat pipes except magnesium oxide (MgO). So, we initiate our idea to use MgO nanofluids in flat plate heat pipe as a working fluid material. MgO nanopowders were synthesized by wet chemical method. Solid state characterizations of synthesized nanopowders were carried out by Ultraviolet Spectroscopy (UV), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques. Synthesized nanopowders were prepared as nanofluids by adding water and as well as water/ethylene glycol as a binary mixture. Thermal conductivity measurements of prepared nanofluids were studied using transient hot-wire apparatus. Response surface methodology based on the Box-Behnken design was implemented to investigate the influence of temperature (30-60∘C), particle fraction (1.5-4.5 vol.%), and solution pH (4-12) of nanofluids as the independent variables. A total of 17 experiments were accomplished for the construction of second-order polynomial equations for target output. All the influential factors, their mutual effects and their quadratic terms were statistically validated by analysis of variance (ANOVA). The optimum stability and thermal conductivity of MgO nanofluids with various temperature, volume fraction and solution pH were predicted and compared with experimental results. The results revealed that increase in particle fraction and pH of MgO nanofluids at certain points would increase thermal conductivity and become stable at nominal temperature.

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)

Graphitic encapsulation of MgO and Fe3C nanoparticles in the reaction of iron pentacarbonyl with magnesium

International Nuclear Information System (INIS)

Dyjak, Sławomir; Cudziło, Stanisław; Polański, Marek; Budner, Bogusław; Bystrzycki, Jerzy

2013-01-01

A simple method to produce highly ordered carbon nanostructures by combustion synthesis is presented. Graphite-encapsulated magnesium oxide, iron carbide nanoparticles and carbon nanobelts were synthesized by the one-step reduction of iron pentacarbonyl with magnesium. High-resolution transmission electron microscopy analysis of the products revealed nanocrystalline MgO and Fe 3 C particles surrounded by a well-crystallized, tight graphite film. The possible formation mechanism is presented and discussed. - Highlights: • We present a simple method to produce highly ordered carbon nanostructures by combustion synthesis. • The cubic MgO particles are completely coated by tight graphitic shells. • The mechanism of formation a distant carbon film on MgO surface has been discussed. • The presented method can be applied to synthesis of other core-shell structures

Development of melt compositions for sulphate bearing high level waste

International Nuclear Information System (INIS)

Jahagirdar, P.B.; Wattal, P.K.

1997-09-01

The report deals with the development and characterization of vitreous matrices for sulphate bearing high level waste. Studies were conducted in sodium borosilicate and lead borosilicate systems with the introduction of CaO, BaO, MgO etc. Lead borosilicate system was found to be compatible with sulphate bearing high level wastes. Detailed product evaluation carried on selected formulations is also described. (author)

The beneficiation of mumbwa phosphate deposit by various ...

African Journals Online (AJOL)

The chemical composition of the ore averages 22.7 % P2O5 with the other constituents being 22.8% SiO2, 19.0% CaO, 7.0% Fe2O3, 4.0 % Al2O3 and 0.2% MgO. Beneficiation studies were performed to investigate methods of concentrating the phosphate values. Preliminary investigations involved detailed identification of ...

PETROLOGY AND GEOCHEMISTRY OF CALC-SILICATE SCHISTS ...

African Journals Online (AJOL)

DR OKONKOWO

2012-02-29

silicate reaction bands have higher contents of CaO and Sr and lower concentrations of K2O, Rb, Ni, and Ba relative to the calc-silicate schists; and relatively higher SiO2, TiO2, Al2O3, Fe2O3, MgO, Na2O, K2O and P2O5 and lower ...

K-AR AGES, MINERALOGY, MAJOR AND TRACE ELEMENT ...

African Journals Online (AJOL)

The mafic rocks are characterised by high Fe2O3, TiO2, MgO, CaO and variable enrichment in compatible trace elements (Cr, Ni, Co) all of which abruptly decrease with increase in fractionation. Na2O, K2O and Al2O3 and the LILE increase with magma differentiation. Normalised incompatible trace elements show marked ...

Etching mechanism of MgO thin films in inductively coupled Cl2/Ar plasma

International Nuclear Information System (INIS)

Efremov, A.M.; Koo, Seong-Mo; Kim, Dong-Pyo; Kim, Kyoung-Tae; Kim, Chang-Il

2004-01-01

The etching mechanism of MgO thin films in Cl 2 /Ar plasma was investigated. It was found that the increasing Ar in the mixing ratio of Cl 2 /Ar plasma causes nonmonotonic MgO etch rate, which reaches a maximum value at 70%Ar+30%Cl 2 . Langmuir probe measurement showed the noticeable influence of Cl 2 /Ar mixing ratio on electron temperature and electron density. The zero-dimensional plasma model indicated monotonic changes of both densities and fluxes of active species. At the same time, analyses of surface kinetics showed the possibility of nonmonotonic etch rate behavior due to the concurrence of physical and chemical pathways in ion-assisted chemical reaction

Efectividad de la administración de sales de rehidratación oral (SRO, en el marco del programa EDA

Directory of Open Access Journals (Sweden)

Leonardo Arévalo Mora

2002-10-01

Full Text Available Objective: To determine the effectiveness that have the salts of oral rehydration in the patients that with the diagnosis of acute diarrheal disease. Design. Systematic revision of randomized controlled studies. Sources of data: Medline (1966-2001, Cochrane library, (1993 to 2001 and Ovid (1982 to 2001, bibliographies of the included studies that it was revised if this was pertinent Study: 31 studies that included 4518 randomized patients. Methods: The selected studies were regrouped in subgroups by the components that were compared in the intervention. Those which besides the salts of oral rehydration (SRO they included solutions with low osmolarity, based on rice, or with the addition of supplements like citrato, zinc, alanine, lactoalbuline, and g1utamine. Results: A high proportion of studies showed the advantage that shows the salts of oral rehydration recornmended by the World Organization of the Health and the Pan-American Organization from the Health when improving the clinical square of the patients with diagnoses of diarrhea and dehydration. It was evidences a better answer with the SRO of low osmolarity, although not in all the studies it was statistically Significant. Conclusions: This work demonstrated that the salts of oral rehydration reduce the number of depositions, its diminish the time of evolution of the diarrhea, its diminished the rate of mortality, the time of stay in the hospitals, and its cooperated to recover of the state of dehydration and to obtain a gain of weight in the firsts hours. The therapy of oral rehydration is probably one of the biggest medical advances in the XX century.

Sintering, microstructure and electrical conductivity of gadolinia-doped ceria with SrO, TiO2 and SrTiO3

International Nuclear Information System (INIS)

Dias, Maria Cely Freitas

2013-01-01

Ceria containing trivalent rare-earths is a solid electrolyte with higher ionic conductivity than the standard yttria fully-stabilized zirconia ionic conductor. This property turns these ceria-based ionic conductors promising materials for application in solid oxide fuel cells operating at intermediate temperatures (500-700 deg C). One of the most utilized approaches to optimize the electrical conductivity and other properties of these materials is the introduction of a second additive. In this work, ceria-20 mol% gadolinia with additions of 1, 2.5 and 5 mol% of SrO, TiO 2 and SrTiO 3 as co-additives were prepared by solid state reaction. The main purpose was to investigate the effects of the co-additives on densification, microstructure and electrical conductivity of the solid electrolyte. Sintered pellets were characterized by apparent density, X-ray diffraction, Raman spectroscopy, scanning electron microscopy and electrical conductivity by impedance spectroscopy. The additives were found to exert different influences in all studied properties. The way they influence the solid electrolyte properties depends on the type and content of the additive. SrO addition to doped ceria improves the intergranular conductivity, but decreases the apparent density of the pellets. Increase of densification was obtained with TiO 2 addition. This additive promotes increase of the blocking of charge carriers at the grain boundaries due to solute exsolution and formation of the pyrochlore Gd 2 Ti 2 O 7 phase at grain boundaries for contents in excess of the solubility limit. No influence on densification was found for SrTiO 3 additions. (author)

Nanocavity formation processes in MgO(100) by light ion (D, He, Li) and heavy ion (Kr, Cu, Au) implantation

NARCIS (Netherlands)

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

2002-01-01

In studies on the controlled growth of metallic precipitates in MgO it is attempted to use nanometer size cavities as precursors for formation of metallic precipitates. In MgO nanocavities can easily be generated by light gas ion bombardment at room temperature with typically 30 keV ion energy to a

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.

Co{sub 2}FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

Energy Technology Data Exchange (ETDEWEB)

Belmeguenai, M., E-mail: belmeguenai.mohamed@univ-paris13.fr; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P. [LSPM (CNRS-UPR 3407), 99 avenue Jean-Baptiste Clément, Université Paris 13, 93430 Villetaneuse (France); Gabor, M. S., E-mail: mihai.gabor@phys.utcluj.ro; Petrisor, T. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Tiusan, C. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F–54506 Vandoeuvre (France)

2014-01-28

10 nm and 50 nm Co{sub 2}FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T{sub a}), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T{sub a}, while the uniaxial anisotropy field is nearly unaffected by T{sub a} within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T{sub a}. Finally, the FMR linewidth decreases when increasing T{sub a}, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10{sup −3} and 1.3×10{sup −3} for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

Comportamento do índice de refração do composto MgO em altas pressões

OpenAIRE

Naira Maria Balzaretti

1988-01-01

O presente trabalho envolve medidas do índice de refração no MgO como função de pressão, através de um micro-interferômetro deste material, colocado no interior de uma camara de alta pressão do tipo bigornas de diamante. In this work we measured the pressure dependence of the refractive index of MgO. A micro-interferometer of this material was inserted into a diamond anvil cell.

Solubility of metal oxides in molten equimolar KBr-NaBr mixture at 973 K

Science.gov (United States)

Cherginets, V. L.; Rebrova, T. P.; Naumenko, V. A.

2014-09-01

Solubility products (p K s,MO, molality) are measured by potentiometric titration with a Pt(O2)|ZrO2(Y2O3) oxygen electrode in the molten KBr-NaBr equimolar mixture at 973 K for the following oxides: CaO (5.00 ± 0.3), MnO (7.85 ± 0.3), NiO (9.72 ± 0.04), PbO (5.20 ± 0.3), and SrO (3.81 ± 0.3). The correlation between p K s,MeO and the polarization of the corresponding cations by Goldschmidt is obtained.

MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K

Science.gov (United States)

Fat'yanov, O. V.; Asimow, P. D.

2014-05-01

Continuing our effort to obtain experimental constraints on the melting curve of MgO at 100-200 GPa, we extended our target preheating capability to 2300 K. Our new Mo capsule design holds a long MgO crystal in a controlled thermal gradient until impact by a Ta flyer launched at up to 7.5 km/s on the Caltech two-stage light-gas gun. Radiative shock temperatures and rarefaction overtake times were measured simultaneously by a 6-channel VIS/NIR pyrometer with 3 ns time resolution. The majority of our experiments showed smooth monotonic increases in MgO sound speed and shock temperature with pressure from 197 to 243 GPa. The measured temperatures as well as the slopes of the pressure dependences for both temperature and sound speed were in good agreement with those calculated numerically for the solid phase at our peak shock compression conditions. Most observed sound speeds, however, were ~800 m/s higher than those predicted by the model. A single unconfirmed data point at 239 GPa showed anomalously low temperature and sound speed, which could both be explained by partial melting in this experiment and could suggest that the Hugoniot of MgO preheated to 2300 K crosses its melting line just slightly above 240 GPa.

MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K

International Nuclear Information System (INIS)

Fat'yanov, O V; Asimow, P D

2014-01-01

Continuing our effort to obtain experimental constraints on the melting curve of MgO at 100-200 GPa, we extended our target preheating capability to 2300 K. Our new Mo capsule design holds a long MgO crystal in a controlled thermal gradient until impact by a Ta flyer launched at up to 7.5 km/s on the Caltech two-stage light-gas gun. Radiative shock temperatures and rarefaction overtake times were measured simultaneously by a 6-channel VIS/NIR pyrometer with 3 ns time resolution. The majority of our experiments showed smooth monotonic increases in MgO sound speed and shock temperature with pressure from 197 to 243 GPa. The measured temperatures as well as the slopes of the pressure dependences for both temperature and sound speed were in good agreement with those calculated numerically for the solid phase at our peak shock compression conditions. Most observed sound speeds, however, were ∼800 m/s higher than those predicted by the model. A single unconfirmed data point at 239 GPa showed anomalously low temperature and sound speed, which could both be explained by partial melting in this experiment and could suggest that the Hugoniot of MgO preheated to 2300 K crosses its melting line just slightly above 240 GPa.

The influence of incorporating MgO into Ni-based cermets by plasma spraying on anode microstructural and chemical stability in dry methane

Science.gov (United States)

Lay, E.; Metcalfe, C.; Kesler, O.

2012-11-01

The Solution Precursor Plasma Spray (SPPS) process was successfully used to deposit cermet coatings that exhibit fine microstructures with high surface area. MgO addition in Ni-YSZ and Ni-SDC cermets results in (Ni,Mg)O solid solution formation, and nickel particles after reduction are finer than in coatings without magnesia. The influence of MgO on the chemical stability of cermets in anodic operating conditions is discussed. It was found that a sufficient amount of magnesia addition (Ni0.9(MgO)0.1) helps to reduce carbon deposition in dry methane.

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.

Multicomponent Diffusion in Experimentally Cooled Melt Inclusions

Science.gov (United States)

Saper, L.; Stolper, E.

2017-12-01

Glassy olivine-hosted melt inclusions are compositionally zoned, characterized by a boundary layer depleted in olivine-compatible components that extends into the melt inclusion from its wall. The boundary layer forms in response to crystallization of olivine and relaxes with time due to diffusive exchange with the interior of the inclusion. At magmatic temperatures, the time scale for homogenization of inclusions is minutes to hours. Preservation of compositional gradients in natural inclusions results from rapid cooling upon eruption. A model of MgO concentration profiles that couples crystal growth and diffusive relaxation of a boundary layer can be used to solve for eruptive cooling rates [1]. Controlled cooling-rate experiments were conducted to test the accuracy of the model. Mauna Loa olivine containing >80 µm melt inclusions were equilibrated at 1225°C in a 1-atm furnace for 24 hours, followed by linear cooling at rates of 102 - 105 °C/hr. High-resolution concentration profiles of 40 inclusions were obtained using an electron microprobe. The model of [1] fits the experimental data with low residuals and the best-fit cooling rates are within 30% of experimental values. The initial temperature of 1225 °C is underestimated by 65°C. The model was modified using (i) MELTS to calculate the interface melt composition as a function of temperature, and (ii) a concentration-dependent MgO diffusion coefficient using the functional form of [2]. With this calibration the best-fit starting temperatures are within 5°C of the experimental values and the best-fit cooling rates are within 20% of experimental rates. The evolution of the CaO profile during cooling is evidence for strong diffusive coupling between melt components. Because CaO is incompatible in olivine, CaO concentrations are expected to be elevated in the boundary layer adjacent to the growing olivine. Although this is observed at short time scales, as the profile evolves the CaO concentration near the

Quantification of MgO surface excess on the SnO{sub 2} nanoparticles and relationship with nanostability and growth

Energy Technology Data Exchange (ETDEWEB)

Gouvea, Douglas, E-mail: dgouvea@usp.br [Departamento de Engenharia Metalurgica e de Materiais, Escola Politecnica, University of Sao Paulo, Av. Prof. Melo Moraes, 2463, Sao Paulo, CEP 05508-930, SP (Brazil); Pereira, Gilberto J. [Department of Materials Engineering, FEI University Center, Sao Bernardo do Campo, SP 09850-901 (Brazil); Gengembre, Leon [University Lille Nord de France, F-59000 Lille, 2USTL, Unite de Catalyse et de Chimie du Solide F-59652 Villeneuve d' Ascq, CNRS, UMR8181, ENSCL, UCCS F-59655 Villeneuve d' Ascq (France); Steil, Marlu C. [Laboratoire d' Electrochimie et de Physico-chimie des Materiaux et des Interfaces (LEPMI), CNRS, UJF, Grenoble-INP, 1130 Rue de la Piscine, B.P. 75, 38402 Saint Martin d' Heres Cedex (France); Roussel, Pascal; Rubbens, Annick [University Lille Nord de France, F-59000 Lille, 2USTL, Unite de Catalyse et de Chimie du Solide F-59652 Villeneuve d' Ascq, CNRS, UMR8181, ENSCL, UCCS F-59655 Villeneuve d' Ascq (France); Hidalgo, Pilar [Departamento de Engenharia Metalurgica e de Materiais, Escola Politecnica, University of Sao Paulo, Av. Prof. Melo Moraes, 2463, Sao Paulo, CEP 05508-930, SP (Brazil); Castro, Ricardo H.R. [Chemical Engineering and Materials Science Department and NEAT ORU, UC Davis, CA 95616 (United States)

2011-02-15

In this work, we experimentally showed that the spontaneous segregation of MgO as surface excess in MgO doped SnO{sub 2} nanoparticles plays an important role in the system's energetics and stability. Using X-ray fluorescence in specially treated samples, we quantitatively determined the fraction of MgO forming surface excess when doping SnO{sub 2} with several different concentrations and established a relationship between this amount and the surface energy of the nanoparticles using the Gibbs approach. We concluded that the amount of Mg ions on the surface was directly related to the nanoparticles total free energy, in a sense that the dopant will always spontaneously distribute itself to minimize it if enough diffusion is provided. Because we were dealing with nanosized particles, the effect of MgO on the surface was particularly important and has a direct effect on the equilibrium particle size (nanoparticle stability), such that the lower the surface energy is, the smaller the particle sizes are, evidencing and quantifying the thermodynamic basis of using additives to control SnO{sub 2} nanoparticles stability.

Ex Situ and Operando Studies on the Role of Copper in Cu-Promoted SiO2-MgO Catalysts for the Lebedev Ethanol-to-Butadiene Process

NARCIS (Netherlands)

Angelici, Carlo|info:eu-repo/dai/nl/345731506; Meirer, Florian; van der Eerden, Ad M. J.|info:eu-repo/dai/nl/304840483; Schaink, Herrick L.; Goryachev, Andrey; Hofmann, Jan P.|info:eu-repo/dai/nl/355351110; Hensen, Emiel J. M.; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X

2015-01-01

Dehydrogenation promoters greatly enhance the performance of SiO2-MgO catalysts in the Lebedev process. Here, the effect of preparation method and order of addition of Cu on the structure and performance of Cu-promoted SiO2-MgO materials is detailed. Addition of Cu to MgO via incipient wetness

Structural characterization of ZnO films grown by molecular beam epitaxy on sapphire with MgO buffer

International Nuclear Information System (INIS)

Pecz, B.; El-Shaer, A.; Bakin, A.; Mofor, A.-C.; Waag, A.; Stoemenos, J.

2006-01-01

The structural characteristics of the ZnO film grown on sapphire substrate using a thin MgO buffer layer were studied using transmission electron microscopy and high-resolution x-ray diffraction. The growth was carried out in a modified plasma-molecular beam epitaxy system. The observed misfit dislocations were well confined at the sapphire overgrown interface exhibiting domain matching epitaxy, where the integral multiples of lattice constants match across the interface. The main extended defects in the ZnO film were the threading dislocations having a mean density of 4x10 9 cm -2 . The formation of the MgO buffer layer as well as the ZnO growth were monitored in situ by reflection high-energy electron diffraction. The very thin ∼1 nm, MgO buffer layer can partially interdiffuse with the ZnO as well as react with the Al 2 O 3 substrate forming an intermediate epitaxial layer having the spinel (MgO/Al 2 O 3 ) structure

Preparation of MgO Films as Buffer Layers by Laser-ablation at Various Substrate Temperatures

Institute of Scientific and Technical Information of China (English)

LI Ling; WANG Chuanbin; WANG Fang; SHEN Qiang; ZHANG Lianmeng

2011-01-01

MgO thin films were deposited on Si(100) substrates by laser ablation under various substrate temperatures (Tsub),expecting to provide a candidate buffer layer for the textured growth of functional perovskite oxide films on Si substrates.The effect of Tsub on the preferred orientation,crystallinity and surface morphology of the films was investigated.MgO films in single-phase were obtained at 473-973 K.With increasing Tsub,the preferred orientation of the films changed from (200) to (111).The crystallinity and surface morphology was different too,depending on Tsub·At Tsub=673 K,the MgO film became uniform and smooth,exhibiting high crystallinity and a dense texture.

Magnesium Vacancy Segregation and Fast Pipe Diffusion for the ½{110} Edge Dislocation in MgO

Science.gov (United States)

Walker, A. M.; Zhang, F.; Wright, K.; Gale, J. D.

2009-12-01

The movement of point defects in minerals plays a key role in determining their rheological properties, both by permitting diffusional creep and by allowing recovery by dislocation climb. Point defect diffusion can also control the kinetics of phase transitions and grain growth, and can determine the rate of chemical equilibration between phases. Because of this, and the difficulties associated with experimental studies of diffusion, the simulation of point defect formation and migration has been a subject of considerable interest in computational mineral physics. So far, studies have concentrated on point defects moving through otherwise perfect crystals. In this work we examine the behavior of magnesium vacancies close to the core of an edge dislocation in MgO and find that the dislocation dramatically changes the behavior of the point defect. An atomic scale model of the ½{110} edge dislocation in MgO was constructed by applying the anisotropic linear elastic displacement field to the crystal structure and subsequently minimizing the energy of the crystal close to the dislocation core using a parameterized potential model. This process yielded the structure of an isolated edge dislocation in an otherwise perfect crystal. The energy cost associated with introducing magnesium vacancies around the dislocation was then mapped and compared to the formation energy of an isolated magnesium vacancy in bulk MgO. We find that the formation energy of magnesium vacancies around the dislocation mirrors the elastic strain field. Above the dislocation line σxx and σyy are negative and the strain field is compressional. Atoms are squeezed together to make room for the extra half plane effectively increasing the pressure in this region. Below the dislocation line σxx and σyy are positive and the strain field is dilatational. Planes of atoms are pulled apart to avoid a discontinuity across the glide plane and the effective pressure is decreased. In the region with a

Positronium hydride in hydrogen-laden thermochemically reduced MgO single crystals

Science.gov (United States)

Pareja, R.; de La Cruz, R. M.; Pedrosa, M. A.; González, R.; Chen, Y.

1990-04-01

Thermochemical reduction of hydrogen-laden MgO single crystals at T~2400 K results in a large concentration of both hydride (H-) ions and anion vacancies (>1024 m-3). Positron-lifetime experiments of these crystals provide evidence for bound positronium hydride states also referred to as [e+-H-] or PsH states. The presence of the anion vacancies was found to inhibit the formation of these states. After thermally annealing out these vacancies, such that H- concentration remains intact, two long-lived components appear in the lifetime spectrum. Furthermore, these two components correlate with the presence of the H-ions. These results suggest the existence of bound [e+-H-] states when positrons are trapped by the H- ions, and the subsequent formation of positronium (Ps) states by the dissociation of the [e+-H-] states. From the values of the intermediate lifetime component, a value of (570+/-50) ps is obtained for the lifetime of the PsH state located in an anion vacancy in MgO. The longest lifetime component ~(1-3) ns is attributed to pick-off annihilation of ortho-Ps states.

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.

Effect of MgO on compositions of the system CaO-Al2O3-Fe2O3. Solubility

Directory of Open Access Journals (Sweden)

Palomo, Ángel

1986-12-01

Full Text Available Five different compositions belonging to the equilibrium system CaO-Al2O3-Fe2O3 were dopep with a fixed quantity of MgO (6,5% wt. The compositions, which lie in different primary fields of crystallization and in different triangles of compatibility, were submitted to several thermal treatments. Each composition, which had previously been melted, originates in its solidification the aluminates and ferrites which are usual in the interstitial phase of clinker Portland, although they are in different microstructural arrangements. The effect of MgO on the generated microstructures has been shown. Also, the solubility of MgO on the aluminic and ferritic phases has been measured.CCinco composiciones diferentes pertenecientes al sistema de equilibrio CaO-Al2O3-Fe2O3 fueron dopadas con una cantidad fija de MgO (6,5%. Las cinco composiciones, que están situadas sobre diferentes campos primarios de cristalización y/o sobre diferentes triángulos de compatibilidad, fueron sometidas a varios tratamientos térmicos. Cada composición (previamente fundida origina en su solidificación los aluminatos y ferritos habituales en la fase intersticial del clinker portland, aunque ordenados en microestructuras diferentes. Se ha comprobado el efecto del MgO sobre las microestructuras generadas, así como su solubilidad en las fases alumínicas y ferríticas.

Synthesis of monoclinic Celsian from Coal Fly Ash by using a one-step solid-state reaction process

Energy Technology Data Exchange (ETDEWEB)

Long-Gonzalez, D.; Lopez-Cuevas, J.; Gutierrez-Chavarria, C.A.; Pena, P.; Baudin, C.; Turrillas, X. [CINVESTAV, Coahuila (Mexico)

2010-03-15

Monoclinic (Celsian) and hexagonal (Hexacelsian) Ba1-xSrxAl{sub 2}Si2O8 solid solutions, where x=0, 0.25, 0.375, 0.5, 0.75 or 1, were synthesized by using Coal Fly Ash (CFA) as main raw material, employing a simple one-step solid-state reaction process involving thermal treatment for 5 h at 850-1300{sup o}C. Fully monoclinic Celsian was obtained at 1200{sup o} C/5 h, for SrO contents of 0.25 {<=} x {<=} 0.75. However, an optimum SrO level of 0.25 {<=} x {<=} 0.375 was recommended for the stabilization of Celsian. These synthesis conditions represent a significant improvement over the higher temperatures, longer times and/or multi-step processes needed to obtain fully monoclinic Celsian, when other raw materials are used for this purpose, according to previous literature. These results were attributed to the role of the chemical and phase constitution of CFA as well as to a likely mineralizing effect of CaO and TiO{sub 2} present in it, which enhanced the Hexacelsian to Celsian conversion.

Indikativní výnosové ocenění společnosti Deloitte Audit s.r.o zjednodušeným způsobem

OpenAIRE

Kuchyňa, Pavel

2010-01-01

Objective of this thesis is to evaluate Deloitte Audit s.r.o. company especially for the purposes of possible changes in structure of the group. This is a shortened simple version of standard evaluation process within the range of about 30 pages. Before using of DCF Equity method, financial and strategic analyses are elaborated and then financial plan is build on base of value drivers estimates.

Sintering, microstructure and electrical conductivity of gadolinia-doped ceria with SrO, TiO{sub 2} and SrTiO{sub 3}; Sinterizacao, microestrutura e condutividade eletrica da ceria-gadolinia com adicoes de SrO, TiO{sub 2} e SrTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Dias, Maria Cely Freitas

2013-07-01

Ceria containing trivalent rare-earths is a solid electrolyte with higher ionic conductivity than the standard yttria fully-stabilized zirconia ionic conductor. This property turns these ceria-based ionic conductors promising materials for application in solid oxide fuel cells operating at intermediate temperatures (500-700 deg C). One of the most utilized approaches to optimize the electrical conductivity and other properties of these materials is the introduction of a second additive. In this work, ceria-20 mol% gadolinia with additions of 1, 2.5 and 5 mol% of SrO, TiO{sub 2} and SrTiO{sub 3} as co-additives were prepared by solid state reaction. The main purpose was to investigate the effects of the co-additives on densification, microstructure and electrical conductivity of the solid electrolyte. Sintered pellets were characterized by apparent density, X-ray diffraction, Raman spectroscopy, scanning electron microscopy and electrical conductivity by impedance spectroscopy. The additives were found to exert different influences in all studied properties. The way they influence the solid electrolyte properties depends on the type and content of the additive. SrO addition to doped ceria improves the intergranular conductivity, but decreases the apparent density of the pellets. Increase of densification was obtained with TiO{sub 2} addition. This additive promotes increase of the blocking of charge carriers at the grain boundaries due to solute exsolution and formation of the pyrochlore Gd{sub 2}Ti{sub 2}O{sub 7} phase at grain boundaries for contents in excess of the solubility limit. No influence on densification was found for SrTiO{sub 3} additions. (author)

Stabilization of Reactive MgO Surfaces by Ni Doping

Science.gov (United States)

Mazheika, Aliaksei; Levchenko, Sergey V.

Ni-MgO solid solutions are promising materials for catalytic reduction of CO2 and dry reforming of CH4. To explain the catalytic activity, an ab initio study of Ni-substitutional defects in MgO (NiMg) has been performed. At first, the validation of the theory level was done. We compared results of CCSD(T) embedded-cluster calculations of NiMg formation energies and adsorption energies of CO, CO2 and H2 on them to the HSE(α) hybrid DFT functional with the fraction of the exact exchange α varied between 0 and 1. HSE(0.3) was found to be the best compromise in this study. Our periodic HSE(0.3) calculations show that NiMg defects are most stable at corner sites, followed by steps, and are least stable at (001) terraces. Thus, Ni-doping stabilizes stepped MgO surfaces. The dissociative adsorption of H2 on the terrace is found to be endothermic (+ 1 . 1 eV), whereas on (110) surface with NiMg it is highly exothermic (- 1 . 6 eV). Adsorbed CO2 is also significantly stabilized (- 0 . 6 vs. - 2 . 2 eV). These findings explain recent microcalorimetry measurements of H2 and CO2 adsorption at doped Ni-MgO samples. partially supported by UniCat (Deutsche Forschungsgemeinschaft).

Sequel of MgO nanoparticles in PLACL nanofibers for anti-cancer therapy in synergy with curcumin/β-cyclodextrin

International Nuclear Information System (INIS)

Sudakaran, Shruthi Vathaluru; Venugopal, Jayarama Reddy; Vijayakumar, Gnaneshwar Puvala; Abisegapriyan, Sivasubramanian; Grace, Andrews Nirmala; Ramakrishna, Seeram

2017-01-01

Pharmaceutical industries spend more money in developing new and efficient methods for delivering successful drugs for anticancer therapy. Electrospun nanofibers and nanoparticles loaded with drugs have versatile biomedical applications ranging from wound healing to anticancer therapy. We aimed to attempt for fabricating elastomeric poly (L-lactic acid-co-ε-caprolactone) (PLACL) with Aloe Vera (AV), magnesium oxide (MgO) nanoparticles, curcumin (CUR) and β-cyclodextrin (β-CD) composite nanofibers to control the growth of MCF-7 cells for breast cancer therapy. The study focused on the interaction of MgO nanoparticle with CUR and β-CD inhibiting the proliferation of Michigan Cancer Foundation-7 (MCF-7) breast cancer cells. FESEM micrographs of fabricated electrospun PLACL, PLACL/AV, PLACL/AV/MgO, PLACL/AV/MgO/CUR and PLACL/AV/MgO/β-CD nanofibrous scaffolds achieved bead free, random and uniform nanofibers with fiber diameter in the range of 786 ± 286, 507 ± 171, 334 ± 95, 360 ± 94 and 326 ± 80 nm respectively. Proliferation of MCF-7 cells was decreased by 65.92% in PLACL/AV/MgO/CUR with respect to PLACL/AV/MgO nanofibrous scaffolds on day 9. The obtained results proved that 1% CUR interacting with MgO nanoparticles showed higher inhibition of MCF-7 cells among all other nanofibrous scaffolds thus serving as a promising biocomposite material system for the breast cancer therapy. - Highlights: • Biocomposite nanofibrous scaffolds fabricated bead free, uniform and possess rough fiber surface • Aloe Vera and MgO nanoparticles initiates cell adhesion and proliferation • CUR (1%)/MgO nanoparticle showed higher level of cell inhibition of MCF-7 cells compared to all other nanofibrous scaffolds • PLACL/AV/MgO/CUR nanofibrous scaffolds proved to be a potential material system for cancer therapy

Sequel of MgO nanoparticles in PLACL nanofibers for anti-cancer therapy in synergy with curcumin/β-cyclodextrin

Energy Technology Data Exchange (ETDEWEB)

Sudakaran, Shruthi Vathaluru [Centre for Nanofibers & Nanotechnology, Mechanical Engineering, Faculty of Engineering, National University of Singapore (Singapore); The Centre for Nanotechnology Research, VIT University, Vellore (India); Venugopal, Jayarama Reddy, E-mail: mpejrv@nus.edu.sg [Centre for Nanofibers & Nanotechnology, Mechanical Engineering, Faculty of Engineering, National University of Singapore (Singapore); Vijayakumar, Gnaneshwar Puvala [Centre for Nanofibers & Nanotechnology, Mechanical Engineering, Faculty of Engineering, National University of Singapore (Singapore); Abisegapriyan, Sivasubramanian [Centre for Nanofibers & Nanotechnology, Mechanical Engineering, Faculty of Engineering, National University of Singapore (Singapore); The Centre for Nanotechnology Research, VIT University, Vellore (India); Grace, Andrews Nirmala [The Centre for Nanotechnology Research, VIT University, Vellore (India); Ramakrishna, Seeram [Centre for Nanofibers & Nanotechnology, Mechanical Engineering, Faculty of Engineering, National University of Singapore (Singapore)

2017-02-01

Pharmaceutical industries spend more money in developing new and efficient methods for delivering successful drugs for anticancer therapy. Electrospun nanofibers and nanoparticles loaded with drugs have versatile biomedical applications ranging from wound healing to anticancer therapy. We aimed to attempt for fabricating elastomeric poly (L-lactic acid-co-ε-caprolactone) (PLACL) with Aloe Vera (AV), magnesium oxide (MgO) nanoparticles, curcumin (CUR) and β-cyclodextrin (β-CD) composite nanofibers to control the growth of MCF-7 cells for breast cancer therapy. The study focused on the interaction of MgO nanoparticle with CUR and β-CD inhibiting the proliferation of Michigan Cancer Foundation-7 (MCF-7) breast cancer cells. FESEM micrographs of fabricated electrospun PLACL, PLACL/AV, PLACL/AV/MgO, PLACL/AV/MgO/CUR and PLACL/AV/MgO/β-CD nanofibrous scaffolds achieved bead free, random and uniform nanofibers with fiber diameter in the range of 786 ± 286, 507 ± 171, 334 ± 95, 360 ± 94 and 326 ± 80 nm respectively. Proliferation of MCF-7 cells was decreased by 65.92% in PLACL/AV/MgO/CUR with respect to PLACL/AV/MgO nanofibrous scaffolds on day 9. The obtained results proved that 1% CUR interacting with MgO nanoparticles showed higher inhibition of MCF-7 cells among all other nanofibrous scaffolds thus serving as a promising biocomposite material system for the breast cancer therapy. - Highlights: • Biocomposite nanofibrous scaffolds fabricated bead free, uniform and possess rough fiber surface • Aloe Vera and MgO nanoparticles initiates cell adhesion and proliferation • CUR (1%)/MgO nanoparticle showed higher level of cell inhibition of MCF-7 cells compared to all other nanofibrous scaffolds • PLACL/AV/MgO/CUR nanofibrous scaffolds proved to be a potential material system for cancer therapy.

Effect of magnesia on the degradability and bioactivity of sol-gel derived SiO2-CaO-MgO-P2O5 system glasses.

Science.gov (United States)

Ma, J; Chen, C Z; Wang, D G; Jiao, Y; Shi, J Z

2010-11-01

Mesoporous 58SiO(2)-(38-x)CaO-xMgO-4P(2)O(5) glasses (where x=0, 5, 10 and 20 mol%) have been prepared by the sol-gel synthesis route. The effects of the substitution of MgO for CaO on glass degradation and bioactivity were studied in tris-(hydroxymethyl)-aminomethane and hydrochloric acid buffer solution (Tris-HCl) and simulated body fluid (SBF), respectively. It is observed that the synthesized glasses with various MgO contents possess the similar textural properties. The studies of in vitro degradability and bioactivity show that the rate of glass degradation gradually decreases with the increase of MgO and the formation of apatite layer on glass surface is retarded. The influences of the composition upon glass properties are explained in terms of their internal structures. Copyright (c) 2010 Elsevier B.V. All rights reserved.

MgO as a non-pyrolyzable pore former in porous membrane supports

DEFF Research Database (Denmark)

Haugen, A. B.; Geffroy, A.; Kaiser, Andreas

2018-01-01

the performance of oxygen transport membranes or other membranes relying on gas transport to the active membrane surface. Thermoplastic feedstocks for extrusion of tubular 3Y-TZP supports were prepared with four different amounts of pyrolyzable pore formers and/or MgO as non-pyrolyzable pore former. The Mg...

occurrence and geochemistry of nafada gypsum, north-eastern nigeria

African Journals Online (AJOL)

DJFLEX

2010-03-18

Mar 18, 2010 ... The container was placed in a. “HERZOG” palletizing machine for 10 seconds after which a pellet was produced. The procedure was repeated for each gypsum sample. Each pellet was analyzed for SiO2, Al2O3, CaO, MgO, SO3, K2O, Na2O,. MgCO3, combine water and purity, using X-ray spectrometer.

Removal of Oil Spills from Salt Water by Magnesium, Calcium ...

African Journals Online (AJOL)

Results obtained showed that treated MgCO3, CaCO3, MgO and CaO with dodecyl benzene sulphonic can sorb oil by 0.95, 1.25, 78, 0.56 times its weight respectively; untreated materials can sorb oil by 0.49, 0.76, 0.44, 0.32 its weight. Characteristics of crude oil and the used materials were investigated by FTIR, X - Ray ...

Microstructural characterisation, physical and chemical properties of ...

African Journals Online (AJOL)

The Energy dispersive x ray spectroscopy (EDX) analysis of rice husk ash performed to determine percentages of silica present in the samples were graphically represented. Nine elements (Al, Si, K, Ca, Br, Fe, Mg, Na, Mn) and their corresponding oxides (Al2O3 , SiO2 , K2O, CaO, Br, Fe2O3 , MgO, Na2 O, MnO) were ...

Band offsets and growth mode of molecular beam epitaxy grown MgO (111) on GaN (0002) by x-ray photoelectron spectroscopy

Science.gov (United States)

Craft, H. S.; Collazo, R.; Losego, M. D.; Mita, S.; Sitar, Z.; Maria, J.-P.

2007-10-01

MgO is a proposed dielectric for use as a tunneling barrier in devices integrating GaN and ferroelectric oxides. In this study, we present data regarding the growth mode and band offsets of MgO grown epitaxially on GaN (0002) surfaces using molecular beam epitaxy. Using in situ x-ray photoelectron spectroscopy (XPS) and molecular beam epitaxy, we determine, from sequential growth experiments, that the growth of MgO proceeds via the Volmer-Weber (three-dimensional) mode, and full coalescence of the film does not occur until approximately 12nm of MgO has been deposited. The observation of a three-dimensional growth mode is in agreement with previously published data. For the valence band offset, we find a value of 1.2±0.2eV, which corresponds to a 3.2eV conduction band offset. XPS measurements suggest a chemically abrupt interface and no effect on band lineup due to the slow coalescence behavior.

Band offsets and growth mode of molecular beam epitaxy grown MgO (111) on GaN (0002) by x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Craft, H. S.; Collazo, R.; Losego, M. D.; Mita, S.; Sitar, Z.; Maria, J.-P.

2007-01-01

MgO is a proposed dielectric for use as a tunneling barrier in devices integrating GaN and ferroelectric oxides. In this study, we present data regarding the growth mode and band offsets of MgO grown epitaxially on GaN (0002) surfaces using molecular beam epitaxy. Using in situ x-ray photoelectron spectroscopy (XPS) and molecular beam epitaxy, we determine, from sequential growth experiments, that the growth of MgO proceeds via the Volmer-Weber (three-dimensional) mode, and full coalescence of the film does not occur until approximately 12 nm of MgO has been deposited. The observation of a three-dimensional growth mode is in agreement with previously published data. For the valence band offset, we find a value of 1.2±0.2 eV, which corresponds to a 3.2 eV conduction band offset. XPS measurements suggest a chemically abrupt interface and no effect on band lineup due to the slow coalescence behavior

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.

Electronic parameters of Sr2M2O7 (M = V, Nb, Ta) and Sr-O chemical bonding

DEFF Research Database (Denmark)

Atuchin, Victor V.; Grivel, Jean-Claude; Zhang, Zhaoming

2010-01-01

XPS measurements were carried out on Sr2Nb2O7 and Sr2Ta2O7 powder samples, which were synthesized using standard solid state method. The binding energy differences between the O 1s and cation core level, Δ(O-Sr) = BE(O 1s) - BE(Sr 3d5/2), was used to characterize the valence electron transfer...... on the formation of the Sr-O bonds. The chemical bonding effects were considered on the basis of our XPS results for Sr2Nb2O7 and Sr2Ta2O7 and the previously published structural and XPS data for other Sr-oxide compounds. A new empirical relationship between Δ(O-Sr) and L(Sr-O) was obtained. Possible applications...

Bone cell-material interactions on metal-ion doped polarized hydroxyapatite

International Nuclear Information System (INIS)

Bodhak, Subhadip; Bose, Susmita; Bandyopadhyay, Amit

2011-01-01

The objective of this work is to study the influence of Mg 2+ and Sr 2+ dopants on in vitro bone cell-material interactions of electrically polarized hydroxyapatite [HAp, Ca 10 (PO 4 ) 6 (OH) 2 ] ceramics with an aim to achieve additional advantage of matching bone chemistry along with the original benefits of electrical polarization treatment relevant to biomedical applications. To achieve our research objective, commercial phase pure HAp has been doped with MgO, and SrO in single, and binary compositions. All samples have been sintered at 1200 deg. C for 2 h and subsequently polarized using an external d.c. field (2.0 kV/cm) at 400 deg. C for 1 h. Combined addition of 1 wt.% MgO/1 wt.% SrO in HAp has been most beneficial in enhancing the polarizability in which stored charge was 4.19 μC/cm 2 compared to pure HAp of 2.23 μC/cm 2 . Bone cell-material interaction has been studied by culturing with human fetal osteoblast cells (hFOB) for a maximum of 7 days. Scanning electron microscope (SEM) images of cell morphology reveal that favorable surface properties and dopant chemistry lead to good cellular adherence and spreading on negatively charged surfaces of both Sr 2+ and Mg 2+ doped HAp samples over undoped HAp. MTT assay results at 7 days show the highest viable cell densities on the negatively charged surfaces of binary doped HAp samples, while positive charged doped HAp surfaces exhibit limited cellular growth in comparison to neutral surfaces.

Study of Optical Humidity Sensing Properties of Sol-Gel Processed TiO2 and MgO Films

Directory of Open Access Journals (Sweden)

B. C. Yadav

2007-04-01

Full Text Available Paper reports a comparative study of humidity sensing properties of TiO2 and MgO films fabricated by Sol-gel technique using optical method. One sensing element of the optical humidity sensor presented here consists of rutile structured two-layered TiO2 thin film deposited on the base of an isosceles glass prism. The other sensing element consists of a film of MgO deposited by same technique on base of the prism. Light from He-Ne laser enters prism from one of refracting faces of the prism and gets reflected from the glass-film interface, before emerging out from its other isosceles face. This emergent beam is allowed to pass through an optical fiber. Light coming out from the optical fiber is measured with an optical power meter. Variations in the intensity of light caused by changes in humidity lying in the range 5%RH to 95%RH have been recorded. MgO film shows better sensitivity than TiO2 film.

Transesterification of palm oil to biodiesel by using waste obtuse horn shell-derived CaO catalyst

International Nuclear Information System (INIS)

Lee, Seik Lih; Wong, Yong Chen; Tan, Yen Ping; Yew, Sook Yan

2015-01-01

Highlights: • Cost effective CaO catalyst derived from waste obtuse horn shells. • The optimum biodiesel yield, 86.75% can be achieved under mild reaction conditions. • The catalyst can be reused up to 3 times with biodiesel yield more than 70%. • Deactivation of catalyst was due to leaching of CaO and pores-filling. - Abstract: The calcium oxide catalysts derived from waste obtuse horn shells were utilized in the transesterification of palm oil into biodiesel. This environment-friendly catalyst is thermally activated at 800 °C for 3 h. The resulting CaO catalyst was characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), temperature-programmed desorption of CO 2 (TPD-CO 2 ), Brunauer–Emmett–Teller (BET) surface area analysis, and scanning electron microscopy (SEM). XRD patterns of calcined catalyst showed intense peaks of calcium oxide, consistent with XRF results that revealed calcium is the major element present in the obtuse horn shells. High calcination temperature (800 °C) tended to promote agglomeration of fine crystals, resulted in a smaller surface area (0.07 m 2 /g) as examined by BET. Catalytic activities in the transesterification process had been investigated using one-variable-at-a-time technique. The optimum palm oil conversion was 86.75% under reaction conditions of 6 h, 5 wt.% of catalyst amount and methanol to oil ratio of 12:1. Reusability of this waste shell derived catalyst was examined and results showed that the prepared catalysts are able to be reused up to 3 times with conversion of more than 70% after the third cycles. Although the reusability may not be excellent at the moment, it is still in the exploratory study. More efforts were done to improve its properties and stability

Surface and local electronic structure modification of MgO film using Zn and Fe ion implantation

Science.gov (United States)

Singh, Jitendra Pal; Lim, Weon Cheol; Lee, Jihye; Song, Jonghan; Lee, Ik-Jae; Chae, Keun Hwa

2018-02-01

Present work is motivated to investigate the surface and local electronic structure modifications of MgO films implanted with Zn and Fe ions. MgO film was deposited using radio frequency sputtering method. Atomic force microscopy measurements exhibit morphological changes associated with implantation. Implantation of Fe and Zn ions leads to the reduction of co-ordination geometry of Mg2+ ions in host lattice. The effect is dominant at bulk of film rather than surface as the large concentration of implanted ions resides inside bulk. Moreover, the evidences of interaction among implanted ions and oxygen are not being observed using near edge fine structure measurements.

Catalytic Upgrading of Biomass Fast Pyrolysis Vapors with Nano Metal Oxides: An Analytical Py-GC/MS Study

Energy Technology Data Exchange (ETDEWEB)

Qiang Lu [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing (China); Zhi-Fei Zhang [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing (China); Chang-Qing Dong [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing (China); Xi-Feng Zhu [Key Laboratory for Biomass Clean Energy of Anhui Province, University of Science and Technology of China, Hefei (China)

2010-10-15

Fast pyrolysis of poplar wood followed with catalytic cracking of the pyrolysis vapors was performed using analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The catalysts applied in this study were nano MgO, CaO, TiO2, Fe2O3, NiO and ZnO. These catalysts displayed different catalytic capabilities towards the pyrolytic products. The catalysis by CaO significantly reduced the levels of phenols and anhydrosugars, and eliminated the acids, while it increased the formation of cyclopentanones, hydrocarbons and several light compounds. ZnO was a mild catalyst, as it only slightly altered the pyrolytic products. The other four catalysts all decreased the linear aldehydes dramatically, while the increased the ketones and cyclopentanones. They also reduced the anhydrosugars, except for NiO. Moreover, the catalysis by Fe2O3 resulted in the formation of various hydrocarbons. However, none of these catalysts except CaO were able to greatly reduce the acids.

First principles and Debye model study of the thermodynamic, electronic and optical properties of MgO under high-temperature and pressure

Science.gov (United States)

Miao, Yurun; Li, Huayang; Wang, Hongjuan; He, Kaihua; Wang, Qingbo

2018-02-01

First principles and quasi-harmonic Debye model have been used to study the thermodynamic properties, enthalpies, electronic and optical properties of MgO up to the core-mantle boundary (CMB) condition (137 GPa and 3700 K). Thermodynamic properties calculation includes thermal expansion coefficient and capacity, which have been studied up to the CMB pressure (137 GPa) and temperature (3700 K) by the Debye model with generalized gradient approximation (GGA) and local-density approximation (LDA). First principles with hybrid functional method (PBE0) has been used to calculate the electronic and optical properties under pressure up to 137 GPa and 0 K. Our results show the Debye model with LDA and first principles with PBE0 can provide accurate thermodynamic properties, enthalpies, electronic and optical properties. Calculated enthalpies show that MgO keep NaCl (B1) structure up to 137 GPa. And MgO is a direct bandgap insulator with a 7.23 eV calculated bandgap. The bandgap increased with increasing pressure, which will induce a blue shift of optical properties. We also calculated the density of states (DOS) and discussed the relation between DOS and band, optical properties. Equations were used to fit the relations between pressure and bandgaps, absorption coefficient (α(ω)) of MgO. The equations can be used to evaluate pressure after careful calibration. Our calculations can not only be used to identify some geological processes, but also offer a reference to the applications of MgO in the future.

X-ray diffraction microstructural analysis of bimodal size distribution MgO nano powder

International Nuclear Information System (INIS)

Suminar Pratapa; Budi Hartono

2009-01-01

Investigation on the characteristics of x-ray diffraction data for MgO powdered mixture of nano and sub-nano particles has been carried out to reveal the crystallite-size-related microstructural information. The MgO powders were prepared by co-precipitation method followed by heat treatment at 500 degree Celsius and 1200 degree Celsius for 1 hour, being the difference in the temperature was to obtain two powders with distinct crystallite size and size-distribution. The powders were then blended in air to give the presumably bimodal-size- distribution MgO nano powder. High-quality laboratory X-ray diffraction data for the powders were collected and then analysed using Rietveld-based MAUD software using the lognormal size distribution. Results show that the single-mode powders exhibit spherical crystallite size (R) of 20(1) nm and 160(1) nm for the 500 degree Celsius and 1200 degree Celsius data respectively with the nano metric powder displays narrower crystallite size distribution character, indicated by lognormal dispersion parameter of 0.21 as compared to 0.01 for the sub-nano metric powder. The mixture exhibits relatively more asymmetric peak broadening. Analysing the x-ray diffraction data for the latter specimen using single phase approach give unrealistic results. Introducing two phase models for the double-phase mixture to accommodate the bimodal-size-distribution characteristics give R = 100(6) and σ = 0.62 for the nano metric phase and R = 170(5) and σ= 0.12 for the σ sub-nano metric phase. (author)

Epitaxial growth of bcc-Fe{sub x}Co{sub 100-x} thin films on MgO(1 1 0) single-crystal substrates

Energy Technology Data Exchange (ETDEWEB)

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

2010-07-15

Fe{sub x}Co{sub 100-x} (x=100, 65, 50 at%) epitaxial thin films were prepared on MgO(1 1 0) single-crystal substrates heated at 300 deg. C by ultra-high vacuum molecular beam epitaxy. The film structure and the growth mechanism are discussed. FeCo(2 1 1) films with bcc structure grow epitaxially on MgO(1 1 0) substrates with two types of variants whose orientations are rotated around the film normal by 180 deg. each other for all compositions. Fe{sub x}Co{sub 100-x} film growth follows the Volmer Weber mode. X-ray diffraction analysis indicates the out-of-plane and the in-plane lattice spacings are in agreement with the values of respective bulk Fe{sub x}Co{sub 100-x} crystals with very small errors less than +-0.4%, suggesting the strains in the films are very small. High-resolution cross-sectional transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the film at the Fe{sub 50}Co{sub 50}/MgO interface along the MgO[1 1-bar 0] direction. The presence of such periodical dislocations decreases the large lattice mismatch of about -17% existing at the FeCo/MgO interface along the MgO[1 1-bar 0] direction.

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.

Study of physical properties of strontium based alumino-borosilicate glasses

Science.gov (United States)

Kaur, Mandeep; Kaur, Gurbinder; Kumar, V.

2018-05-01

In the present study, an attempt has been made to study the influence of CaO/Mgo ratio (R) on different physical properties of (10+x)CaO-(10-x)-MgO-10SrO-10B2O3-20Al2O3-40SiO2 glasses. The novel glass series has been synthesized by melt quenching technique. The parameters like reflection loss and dielectric constant have been determined. Also, molar refraction, molar electronic polarizability and oxygen packing density have been calculated on the basis of measured values of density, molar volume and refractive index of the glasses.

Positronium hydride in hydrogen-laden thermochemically reduced MgO single crystals

International Nuclear Information System (INIS)

Pareja, R.; la Cruz, R.M. de; Pedrosa, M.A.; Gonzalez, R.; Chen, Y.

1990-01-01

Thermochemical reduction of hydrogen-laden MgO single crystals at T∼2400 K results in a large concentration of both hydride (H - ) ions and anion vacancies (>10 24 m -3 ). Positron-lifetime experiments of these crystals provide evidence for bound positronium hydride states also referred to as [e + -H - ] or PsH states. The presence of the anion vacancies was found to inhibit the formation of these states. After thermally annealing out these vacancies, such that H - concentration remains intact, two long-lived components appear in the lifetime spectrum. Furthermore, these two components correlate with the presence of the H - ions. These results suggest the existence of bound [e + -H - ] states when positrons are trapped by the H - ions, and the subsequent formation of positronium (Ps) states by the dissociation of the [e + -H - ] states. From the values of the intermediate lifetime component, a value of (570±50) ps is obtained for the lifetime of the PsH state located in an anion vacancy in MgO. The longest lifetime component ∼(1--3) ns is attributed to pick-off annihilation of ortho-Ps states

Preparation of novel ceramics with high CaO content from steel slag

International Nuclear Information System (INIS)

Zhao, Lihua; Li, Yu; Zhou, Yuanyuan; Cang, Daqiang

2014-01-01

Highlights: • Efficiently utilize such solid waste with high CaO content. • A novel ceramics was put forward by traditional ceramic process. • The novel ceramics attained high strength. • Sintering mechanisms of the novel ceramics were discussed. - Abstract: Steel slag, an industrial waste discharged from steelmaking process, cannot be extensively used in traditional aluminosilicate based ceramics manufacturing for its high content of calcium oxide. In order to efficiently utilize such solid waste, a method of preparing ceramics with high CaO content was put forward. In this paper, steel slag in combination with quartz, talcum, clay and feldspar was converted to a novel ceramic by traditional ceramic process. The sintering mechanism, microstructure and performances were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) techniques, combined experimenting of linear shrinkage, water absorption and flexural strength. The results revealed that all crystal phases in the novel ceramic were pyroxene group minerals, including diopsite ferrian, augite and diopsite. Almost all raw materials including quartz joined the reaction and transformed into pyroxene or glass phase in the sintering process, and different kinds of clays and feldspars had no impact on the final crystal phases. Flexural strength of the ceramic containing 40 wt.% steel slag in raw materials can reach 143 MPa at sintering temperature of 1210 °C and its corresponding water absorption, weight loss, linear shrinkage were 0.02%, 8.8%, 6.0% respectively. Pyroxene group minerals in ceramics would contribute to the excellent physical and mechanical properties

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.

CULTURA ORGANIZACIONAL: UM ESTUDO DE CASO NA EMPRESA MGO

Directory of Open Access Journals (Sweden)

Vagner Luís Wentz

2012-07-01

Full Text Available O tema cultura tem sido objeto de estudo há muitos anos, e as literaturas existentes apontam uma grande diversidade de conceitos, o que torna as organizações grandes fontes de pesquisa. A MGO, uma multinacional fabricante de produtos agrícolas, convive constantemente com mudanças de seus procedimentos, de suas tarefas do cotidiano e de comportamentos por parte de seus colaboradores, uma relação entre “novatos” e “veteranos” que, em alguns casos, é geradora de conflitos, o que pode vir a prejudicar a imagem da companhia. Diante disso, este estudo tem como objetivo geral analisar a cultura organizacional a partir da percepção das lideranças de uma unidade da empresa MGO situada em Montenegro/RS. Esta pesquisa se classifica, quanto aos procedimentos, como bibliográfica e estudo de caso; quanto aos objetivos, como descritiva; e quanto ao problema, esta pesquisa é classificada como qualitativa. A partir da análise dos dados coletados através de entrevistas semiestruturadas com as lideranças de departamentos diferentes, análise de documentos, observação participante e aplicação do teste para identificação da tipologia de cultura, pode-se identificar a cultura da organização e sugerir algumas melhorias que podem ajudar na harmonia do clima da organização. Palavras-chave: Cultura. Clima. Organização.

The effect of the MgO buffer layer thickness on magnetic anisotropy in MgO/Fe/Cr/MgO buffer/MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Kozioł-Rachwał, Anna, E-mail: a.koziolrachwal@aist.go.jp [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, Takayuki; Zayets, Vadym; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Suzuki, Yoshishige [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

2016-08-28

The relationship between the magnetic properties and MgO buffer layer thickness d was studied in epitaxial MgO/Fe(t)/Cr/MgO(d) layers grown on MgO(001) substrate in which the Fe thickness t ranged from 0.4 nm to 1.1 nm. For 0.4 nm ≤ t ≤ 0.7 nm, a non-monotonic coercivity dependence on the MgO buffer thickness was shown by perpendicular magneto-optic Kerr effect magnetometry. For thicker Fe films, an increase in the buffer layer thickness resulted in a spin reorientation transition from perpendicular to the in-plane magnetization direction. Possible origins of these unusual behaviors were discussed in terms of the suppression of carbon contamination at the Fe surface and changes in the magnetoelastic anisotropy in the system. These results illustrate a method to control magnetic anisotropy in MgO/Fe/Cr/MgO(d) via an appropriate choice of MgO buffer layer thickness d.

La enfermería ante el enfoque del caos y la complejidad

OpenAIRE

Peña Marcano, Karem Eydelys; Rodríguez Lastra, Jesús

2003-01-01

La nueva visión de las ciencias médicas y de la relación salud-enfermedad vista a la luz de las ciencias avanzadas que perciben al mundo como un fenómeno complejo y caótico, demanda al trabajador de salud y en particular a la enfermera, un cambio en la forma de pensar y actuar. En este trabajo, se definen algunos de los conceptos de caos, complejidad, fractalidad y se involucra el papel de la enfermera ante esta forma de ver la ciencia, separándose de la geometría e...

Surface structure of MgO underlayer with Ti diffusion for (002 oriented L10 FePt-based heat assisted magnetic recording media

Directory of Open Access Journals (Sweden)

Sintaro Hinata

2018-05-01

Full Text Available Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm/Cr80Mn20 (0-30 nm/Cr50Ti50 (0-50 nm/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

Surface structure of MgO underlayer with Ti diffusion for (002) oriented L10 FePt-based heat assisted magnetic recording media

Science.gov (United States)

Hinata, Sintaro; Jo, Shin; Saito, Shin

2018-05-01

Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm)/Cr80Mn20 (0-30 nm)/Cr50Ti50 (0-50 nm)/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW) on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

Carbon monoxide MgO from dispersed solids to single crystals: a review and new advances

Science.gov (United States)

Spoto, G.; Gribov, E. N.; Ricchiardi, G.; Damin, A.; Scarano, D.; Bordiga, S.; Lamberti, C.; Zecchina, A.

2004-10-01

In this review we describe 30 years of research on the surface properties of magnesium oxide, considered as the model prototype oxide of cubic structure. The surface properties of single crystals, thin films and powdered samples (sintered at progressive higher temperatures) are considered and compared, with the aim of demonstrating that the gap between “believed perfect” single crystal surfaces, typical of “pure” Surface Science, and high surface area samples, typical of Catalysis Science, can be progressively reduced. The surface features considered in this review are the structural (morphological), optical, absorptive and reactive properties. As the carbon monoxide molecule is able to probe the surface properties of both anions and cations, it can give a complete information of the surface structure of MgO samples. For this reason the adsorption and spectroscopy of this molecule is preferentially considered in this review. Particular emphasis is given in reviewing results obtained by high resolution transmission microscopy and in situ IR spectroscopy of adsorbed species (in both reflection and transmission modes), but also UV-Vis diffuse reflectance, photoluminescence, TDS, EPR, electron based techniques are mentioned. Reviewed experimental results are also commented in view of the important theoretical literature available on this topic and are complemented by new transmission IR data concerning CO adsorbed, down to 60 K, on powdered MgO samples with increasing surface area. These innovative experiments allow us to perform, on powdered samples, the adsorption experiments typical of single crystals (or films) Surface Science, with an increase of the S/N of the vibrational features higher than two order of magnitude. As far the new results (never published before) are concerned, we report IR spectra of CO dosed at 60 K on polycrystalline MgO samples with different surface area obtained by Mg(OH) 2 decomposition and progressive sintering at high temperature

MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K

OpenAIRE

Fat'yanov, Oleg V.; Asimow, P. D.

2014-01-01

Continuing our effort to obtain experimental constraints on the melting curve of MgO at 100-200 GPa, we extended our target preheating capability to 2300 K. Our new Mo capsule design holds a long MgO crystal in a controlled thermal gradient until impact by a Ta flyer launched at up to 7.5 km/s on the Caltech two-stage light-gas gun. Radiative shock temperatures and rarefaction overtake times were measured simultaneously by a 6-channel VIS/NIR pyrometer with 3 ns time resolution. The majority ...

Metastable self-trapping of positrons in MgO

Science.gov (United States)

Monge, M. A.; Pareja, R.; González, R.; Chen, Y.

1997-01-01

Low-temperature positron annihilation measurements have been performed on MgO single crystals containing either cation or anion vacancies. The temperature dependence of the S parameter is explained in terms of metastable self-trapped positrons which thermally hop through the crystal lattice. The experimental results are analyzed using a three-state trapping model assuming transitions from both delocalized and self-trapped states to deep trapped states at vacancies. The energy level of the self-trapped state was determined to be (62+/-5) meV above the delocalized state. The activation enthalpy for the hopping process of self-trapped positrons appears to depend on the kind of defect present in the crystals.

Determination of the constituents and suitability of Azara barytes for ...

African Journals Online (AJOL)

Azara baryte was analyzed and had an average specific gravity of 4.3g/cm3 and loss on ignition of 1.71wt%. Atomic Absorption spectrometery was used to determine the Fe2O3,Al2O3 and BaO contents. SiO2 and SO3 were determined by gravimetry while CaO, MgO, Na2O and K2O were determined by flame photometry.

Structure and Bonding in Noncrystalline Solids Abstracts

Science.gov (United States)

1983-06-02

displacement cascades are unlikely. Related damage studies as diffuse X- ray scattering, magnetic susceptibility and positron - annihilation lifetime...the positron annihilation lifetime data; diffuse X-ray scattering studies give evidence for "amorphized" clusters in neutron but not in elec-ron...feldspar glasses and glasses in the system CaO- MgO -SiO 2 . These results indicate that the nearest-neighbor and next- nearest-neighbor environments are very

Geochemistry of the Potassic Basalts from the Bufumbira Volcanic ...

African Journals Online (AJOL)

The various basalts are low in SiO2 wt %, Al2O3 wt % and Na2O wt % but high in MgO wt %, TiO2 wt %, CaO wt %, K2O wt % with K2O/Na2O = 1.08 to 2.07. These are potassic belonging to the kamafugite series. Plots discriminate two geochemical trends corresponding to the picritic and clinopyroxene rich basalts.

Treatment of Liquid Oil Spill by Untreated and Treated Aswanly Clay ...

African Journals Online (AJOL)

The aim of this work is to use cheap, available and recyclable sorbents for oil spill clean – up. α -SiO2-Quartz, Na2Si2O5(OH)4, CaCO3, MgCO3, BaCO3, CaO, MgO, ... Characteristics of crude oil and Aswanly clay were investigated by FTIR, X – Ray Fluorescence, X – Ray Diffraction, pour point and centrifuge instruments.

the effect of high temperatures on concrete incorporating ultrafine ...

African Journals Online (AJOL)

Benkaddour M, Senhadji Y, Kazi Aoual F and Semcha A

1 mai 2016 ... ... CEM II/A 42,5 MPa de la cimenterie LAFARGE de Oggaz (Ouest. Algérien). Ses caractéristiques chimiques, minéralogiques et physiques sont présentées dans les tableaux 1, 2 et 3 respectivement. Tableau 1. Analyse chimique du ciment. Les composants. CaO. SiO2. Al2O3. Fe2O3. MgO SO3. Perte au.

GEOCHEMISTRY AND MINERALOGICAL EVALUATION OF ...

African Journals Online (AJOL)

Dr Osondu

2011-11-05

Nov 5, 2011 ... mica-schist. AAS and XRD techniques were employed in the determination of chemical and mineralogical composition of ten .... Sample %. British Standard. Institution (BSI). %. American standard. (ASTM) %. SiO2. Al2O3. Fe2O3. TiO2. CaO. MgO. Na2O. K2O. P2O5. LO I. 46.65. 47.67. 1.02. 1.28. 0.10. 0.02.

Copper implantation defects in MgO observed by positron beam analysis, RBS and X-TEM

International Nuclear Information System (INIS)

Huis, M.A. van; Fedorov, A.V.; Veen, A. van; Smulders, P.J.M.; Kooi, B.J.; Hosson, J.Th.M. de

2000-01-01

In this work, effects of copper ion implantation in MgO were studied. (1 0 0) MgO samples were implanted with 50 keV Cu ions and thermally annealed stepwise in air for 30 minutes at 550, 750, 1000, 1250 and 1350 K. After ion implantation and after each annealing step, the samples were analysed with positron beam analysis (PBA). Use was also made of Rutherford backscattering spectrometry/channeling (RBS-C) and cross-sectional transmission electron microscopy (X-TEM). The combination of these techniques enabled to monitor the depth resolved evolution of both created defects and the copper atom depth distribution. PBA results show that copper implantation at a dose of 10 15 ions cm -2 yields a single layer of vacancy type defects after annealing. However a copper implantation at a dose of 10 16 ions cm -2 clearly yields two layers of defects in the material after annealing, separated by an intermediate layer. In both layers nanocavities have been identified. RBS experimental results show that the implanted copper atoms diffuse into the bulk material during annealing. X-TEM and channeling results show that after annealing, the lattice of the copper nanoprecipitates is epitaxial to the MgO host lattice. Under some circumstances, copper precipitates and small voids can co-exist. Furthermore, X-TEM measurements show that the nanocavities have rectangular shapes

Vývoj interního manažerského informačního systému ve společnosti Dolphin consulting, s.r.o.

OpenAIRE

Církovský, Tomáš

2016-01-01

Main goal of this master thesis is to create Management Information System for company Dolphin consulting, s.r.o. based on technologies available within its infrastructure. Next goal is conduct preliminary verification of the created Management Information System. Generally, the Management Information System is created in accordance with resources including but not limited to Business Intelligence, Management Information Systems literature and experiences of the author. The most important ass...

Nano-structure formation of Fe-Pt perpendicular magnetic recording media co-deposited with MgO, Al2O3 and SiO2 additives

International Nuclear Information System (INIS)

Safran, G.; Suzuki, T.; Ouchi, K.; Barna, P.B.; Radnoczi, G.

2006-01-01

Perpendicular magnetic recording media samples were prepared by sputter deposition on sapphire with a layer sequence of MgO seed-layer/Cr under-layer/FeSi soft magnetic under-layer/MgO intermediate layer/FePt-oxide recording layer. The effects of MgO, Al 2 O 3 and SiO 2 additives on the morphology and orientation of the FePt layer were investigated by transmission electron microscopy. The samples exhibited (001) orientation of the L1 FePt phase with the mutual orientations of sapphire substrate//MgO(100)[001]//Cr(100)[11-bar0]//FeSi(100)[11-bar0]//MgO(100) [001]//FePt(001)[100]. The morphology of the FePt films varied due to the co-deposited oxides: The FePt layers were continuous and segmented by stacking faults aligned at 54 o to the surface. Films with SiO 2 addition, beside the oriented columnar FePt grains, exhibited a fraction of misoriented crystallites due to random repeated nucleation. Al 2 O 3 addition resulted in a layered structure, i.e. an initial continuous epitaxial FePt layer covered by a secondary layer of FePt-Al 2 O 3 composite. Both components (FePt and MgO) of the MgO-added samples were grown epitaxially on the MgO intermediate layer, so that a nano-composite of intercalated (001) FePt and (001) MgO was formed. The revealed microstructures and formation mechanisms may facilitate the improvement of the structural and magnetic properties of the FePt-oxide composite perpendicular magnetic recording media

The effect of oxygen impurity on the electronic and optical properties of calcium, strontium and barium chalcogenide compounds

International Nuclear Information System (INIS)

Dadsetani, M.; Beiranvand, R.

2010-01-01

Electronic and optical properties of calcium, strontium and barium chalcogenide compounds in NaCl structure are studied using the band structure results obtained through the full potential linearized augmented palne wave method. Different linear relationships are observed between theoretical band gap and 1/a 2 (where a is lattice constant) for calcium, strontium and barium chalcogenide compounds with and without oxygen, respectively. An abnormal behavior of electronic and optical properties are found for compounds containing oxygen. These effects are ascribed to the special properties of Ca-O, Sr-O and Ba-O bonds, which are different from chemical bonds between Ca, Sr and Ba and other chalcogen atoms.

Enhanced bioactivity, biocompatibility and mechanical behavior of strontium substituted bioactive glasses

International Nuclear Information System (INIS)

Arepalli, Sampath Kumar; Tripathi, Himanshu; Hira, Sumit Kumar; Manna, Partha Pratim; Pyare, Ram; Singh, S.P.

2016-01-01

Strontium contained biomaterials have been reported as a potential bioactive material for bone regeneration, as it reduces bone resorption and stimulates bone formation. In the present investigation, the bioactive glasses were designed to partially substitute SrO for SiO 2 in Na 2 O–CaO–SrO–P 2 O 5 –SiO 2 system. This work demonstrates that the substitution of SrO for SiO 2 has got significant benefit than substitution for CaO in the bioactive glass. Bioactivity was assessed by the immersion of the samples in simulated body fluid for different intervals. The formation of hydroxy carbonate apatite layer was identified by X-ray diffractometry, scanning electron microscopy (SEM) and energy dispersive spectroscopy. The elastic modulus of the bioactive glasses was measured and found to increase with increasing SrO for SiO 2 . The blood compatibility of the samples was evaluated. In vitro cell culture studies of the samples were performed using human osteosarcoma U2-OS cell lines and found a significant improvement in cell viability and proliferation. The investigation showed enhancement in bioactivity, mechanical and biological properties of the strontia substituted for silica in glasses. Thus, these bioactive glasses would be highly potential for bone regeneration. - Highlights: • The substitution of SrO was done for SiO 2 in Na 2 O–CaO–SrO–P 2 O 5 –SiO 2 bioactive glass. • Network connectivity significantly influenced on bioactivity and biocompatibility. • In vitro SBF studies showed enhanced HCA crystallinity on the glass surface. • The cell culture studies exhibited better cell compatibility and significant growth. • Density and elastic moduli increased with increasing concentration of strontia.

Enhanced bioactivity, biocompatibility and mechanical behavior of strontium substituted bioactive glasses

Energy Technology Data Exchange (ETDEWEB)

Arepalli, Sampath Kumar, E-mail: askumar.rs.cer11@iitbhu.ac.in [Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Tripathi, Himanshu [Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Hira, Sumit Kumar; Manna, Partha Pratim [Immunobiology Laboratory, Department of Zoology, Banaras Hindu University, Varanasi 221005 (India); Pyare, Ram; Singh, S.P. [Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

2016-12-01

Strontium contained biomaterials have been reported as a potential bioactive material for bone regeneration, as it reduces bone resorption and stimulates bone formation. In the present investigation, the bioactive glasses were designed to partially substitute SrO for SiO{sub 2} in Na{sub 2}O–CaO–SrO–P{sub 2}O{sub 5}–SiO{sub 2} system. This work demonstrates that the substitution of SrO for SiO{sub 2} has got significant benefit than substitution for CaO in the bioactive glass. Bioactivity was assessed by the immersion of the samples in simulated body fluid for different intervals. The formation of hydroxy carbonate apatite layer was identified by X-ray diffractometry, scanning electron microscopy (SEM) and energy dispersive spectroscopy. The elastic modulus of the bioactive glasses was measured and found to increase with increasing SrO for SiO{sub 2}. The blood compatibility of the samples was evaluated. In vitro cell culture studies of the samples were performed using human osteosarcoma U2-OS cell lines and found a significant improvement in cell viability and proliferation. The investigation showed enhancement in bioactivity, mechanical and biological properties of the strontia substituted for silica in glasses. Thus, these bioactive glasses would be highly potential for bone regeneration. - Highlights: • The substitution of SrO was done for SiO{sub 2} in Na{sub 2}O–CaO–SrO–P{sub 2}O{sub 5}–SiO{sub 2} bioactive glass. • Network connectivity significantly influenced on bioactivity and biocompatibility. • In vitro SBF studies showed enhanced HCA crystallinity on the glass surface. • The cell culture studies exhibited better cell compatibility and significant growth. • Density and elastic moduli increased with increasing concentration of strontia.

Preparation of MgO Catalytic Support in Shaped Mesoporous High Surface Area Form

Czech Academy of Sciences Publication Activity Database

Gulková, Daniela; Šolcová, Olga; Zdražil, Miroslav

2004-01-01

Roč. 76, 1-3 (2004), s. 137-149 ISSN 1387-1811 R&D Projects: GA AV ČR IAA4072306 Institutional research plan: CEZ:AV0Z4072921 Keywords : MgO support * sigh Surface area * texture Subject RIV: CC - Organic Chemistry Impact factor: 2.093, year: 2004

Mg/O2 Battery Based on the Magnesium-Aluminum Chloride Complex (MACC) Electrolyte

DEFF Research Database (Denmark)

Vardar, Galin; Smith, Jeffrey G.; Thomson, Travis

2016-01-01

Mg/O2 cells employing a MgCl2/AlCl3/DME (MACC/DME) electrolyte are cycled and compared to cells with modified Grignard electrolytes, showing that performance of magnesium/oxygen batteries depends strongly on electrolyte composition. Discharge capacity is far greater for MACC/DME-based cells, whil...

Lubrication of dislocation glide in MgO by hydrous defects

Science.gov (United States)

Skelton, Richard; Walker, Andrew M.

2018-02-01

Water-related defects, principally in the form of protonated cation vacancies, are potentially able to weaken minerals under high-stress or low-temperature conditions by reducing the Peierls stress required to initiate dislocation glide. In this study, we use the Peierls-Nabarro (PN) model to determine the effect of protonated Mg vacancies on the 1/2{110} and 1/2{100} slip systems in MgO. This PN model is parameterized using generalized stacking fault energies calculated using plane-wave density functional theory, with and without protonated Mg vacancies present at the glide plane. It found that these defects increase dislocation core widths and reduce the Peierls stress over the entire pressure range 0-125 GPa. Furthermore, 1/2{110} slip is found to be more sensitive to the presence of protonated vacancies which increases in the pressure at which {100} becomes the easy glide plane for 1/2 screw dislocations. These results demonstrate, for a simple mineral system, that water-related defects can alter the deformation behavior of minerals in the glide-creep regime by reducing the stress required to move dislocations by glide. (Mg, Fe)O is the most anisotropic mineral in the Earth's lower mantle, so the differential sensitivity of the major slip systems in MgO to hydrous defects has potential implications for the interpretation of the seismic anisotropy in this region.

Precise microwave characterization of MgO substrates for HTS circuits with superconducting post dielectric resonator

International Nuclear Information System (INIS)

Mazierska, Janina; Ledenyov, Dimitri; Jacob, Mohan V; Krupka, Jerzy

2005-01-01

Accurate data of complex permittivity of dielectric substrates are needed for efficient design of HTS microwave planar circuits. We have tested MgO substrates from three different manufacturing batches using a dielectric resonator with superconducting parts recently developed for precise microwave characterization of laminar dielectrics at cryogenic temperatures. The measurement fixture has been fabricated using a SrLaAlO 3 post dielectric resonator with DyBa 2 Cu 3 O 7 end plates and silver-plated copper sidewalls to achieve the resolution of loss tangent measurements of 2 x 10 -6 . The tested MgO substrates exhibited the average relative permittivity of 9.63 and tanδ from 3.7 x 10 -7 to 2 x 10 -5 at frequency of 10.5 GHz in the temperature range from 14 to 80 K

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.

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.

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.

Porosity of Lead Agglomerate as Function of CaO and SiO2 Proportion

OpenAIRE

, A. Haxhiaj; , A. Terziqi; , E. Haxhiaj

2016-01-01

Agglomerate porosity is correlated with strength of its pieces and it is main parameter for reductive melting process in Water-jacket furnace. Treatment is oriented toward achieving porosity and optimal strength. The paper deals with the process in te-mperature about 9000C and with less than 10% composition CaO in rapport with lead. In order to achieve optimal results of agglomerate porosity and quality, it is necessary during the roasting process of lead concentration to correlate the conten...

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 layer...... atmospheric air and N2, H2 for the feed and sweep side respectively. The oxygen permeation was 4 N ml min−1 cm−2 at 850 °C using H2 on one side and air on the other side....

Solid-solid interactions in Co3O4-MoO3/MgO system

International Nuclear Information System (INIS)

Radwan, Nagi R.E.; Ghozza, Ahmed M.; El-Shobaky, Gamil A.

2003-01-01

Cobalt/magnesium mixed oxide solids and cobalt-molybdenum/magnesium mixed oxide solids were prepared by thermal decomposition of basic magnesium carbonate pretreated with different proportions of cobalt nitrate and then with calculated amounts of ammonium molybdate. The proportions of cobalt expressed as Co 3 O 4 were 0.1, 0.2 and 0.3 mol while the concentrations of molybdenum expressed as mol% MoO 3 were 2.5 and 5.0. The prepared mixed solid specimens were calcined in air at 400-1000 deg. C. The solid-solid interactions in Co 3 O 4 -MoO 3 were investigated using DTA, TG and X-ray powder diffraction (XRD) techniques. The results obtained revealed that MgO dissolved cobalt oxide in its lattice forming CoO-MgO solid solution. The amount of cobalt dissolved increases by increasing the temperature in the range 800-1000 deg. C. This finding was confirmed by X-ray diffractograms in which all the diffraction lines of cobalt oxide disappeared at 1000 deg. C. MoO 3 present interacted readily with MgO and cobalt oxide by heat treatment at temperature starting from 400 deg. C producing MgMoO 4 and CoMoO 4 which remained stable by heating at 1000 deg. C. The impregnation of basic magnesium carbonate with cobalt nitrate much enhanced its thermal decomposition yielding MgO, which decomposed completely at 395.5 deg. C instead of 525 deg. C. The formation of magnesium cobaltite (MgCo 2 O 4 ) has been ruled out via XRD investigation at relatively high diffraction angles

[Analysis of X-Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry of Pangxidong Composite Granitoid Pluton and Its Implications for Magmatic Differentiation].

Science.gov (United States)

Zeng, Chang-yu; Ding, Ru-xin; Li, Hong-zhong; Zhou, Yong-zhang; Niu, Jia; Zhang, Jie-tang

2015-11-01

Pangxidong composite granitoid pluton located in the southwestern margin of Yunkai massif. The metamorphic grade of this pluton increases from outside to inside, that is, banded-augen granitic gneisses, gneissoid granites and granites distribute in order from edge to core. X-Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry are conducted to study the geochemical characteristics of the three types of rocks. The result shows that all the three types of rocks are peraluminous rocks and their contents of main elements and rare earth elements change gradually. From granitic gneisses to granites, the contents of Al₂O₃, CaO, MgO, TiO₂, total rare earth elements and light rare earth elements increase, but the contents of SiO₂ and heavy rare earth elements decrease. It is suggested that the phylogenetic relationship exists between granitic gneisses, gneissoid granites and granites during the multi-stage tectonic evolution process. Furthermore, the remelting of metamorphosed supracrustal rocks in Yunkai massif is probably an important cause of granitoid rocks forming. The evolutionary mechanism is probably that SiO₂ and heavy rare earth elements were melt out from the protolith and gradually enriched upward, but Al₂O₃, CaO, MgO, TiO₂ and light rare earth elements enriched downward.

Associated chemical and carbon isotopic composition variations in diamonds from Finsch and Premier kimberlite, South Africa

International Nuclear Information System (INIS)

Deines, P.

1984-01-01

The carbon isotopic composition of 66 inclusion-containing diamonds from the Premier kimberlite, South Africa, 93 inclusion-containing diamonds and four diamonds of two diamond-bearing peridotite xenoliths from the Finsch kimberlite, South Africa was measured. The data suggest a relationship between the carbon isotopic composition of the diamonds and the chemical composition of the associated silicates. For both kimberlites similar trends are noted for diamonds containing peridotite-suite inclusions (P-type) and for diamonds containing eclogite-suite inclusions (E-type): Higher delta 13 C P-type diamonds tend to have inclusions lower in SiO 2 , Al 2 O 3 , Cr 2 O 3 , MgO, Mg/(Mg + Fe) and higher in FeO and CaO. Higher delta 13 C E-type diamonds tend to have inclusions lower in SiO 2 , Al 2 O 3 , MgO, Mg/(Mg + Fe), Na 2 O, K 2 O, TiO 2 and higher in CaO, Ca/(Ca + Mg). Consideration of a number of different models that have been proposed for the genesis of kimberlites, their zenoliths and diamonds shows that they are all consistent with the conclusion that in the mantle, regions exist that are characterized by different mean carbon isotopic compositions. (author)

On how differently the quasi-harmonic approximation works for two isostructural crystals: Thermal properties of periclase and lime

International Nuclear Information System (INIS)

Erba, A.; Dovesi, R.; Shahrokhi, M.; Moradian, R.

2015-01-01

Harmonic and quasi-harmonic thermal properties of two isostructural simple oxides (periclase, MgO, and lime, CaO) are computed with ab initio periodic simulations based on the density-functional-theory (DFT). The more polarizable character of calcium with respect to magnesium cations is found to dramatically affect the validity domain of the quasi-harmonic approximation that, for thermal structural properties (such as temperature dependence of volume, V(T), bulk modulus, K(T), and thermal expansion coefficient, α(T)), reduces from [0 K-1000 K] for MgO to just [0 K-100 K] for CaO. On the contrary, thermodynamic properties (such as entropy, S(T), and constant-volume specific heat, C V (T)) are described reliably at least up to 2000 K and quasi-harmonic constant-pressure specific heat, C P (T), up to about 1000 K in both cases. The effect of the adopted approximation to the exchange-correlation functional of the DFT is here explicitly investigated by considering five different expressions of three different classes (local-density approximation, generalized-gradient approximation, and hybrids). Computed harmonic thermodynamic properties are found to be almost independent of the adopted functional, whereas quasi-harmonic structural properties are more affected by the choice of the functional, with differences that increase as the system becomes softer

Identification of Oxide Compound in Dolomite Mineral from Aceh Tamiang Region

Directory of Open Access Journals (Sweden)

Nirmala Sari

2013-08-01

Full Text Available Indonesia has abundant mineral especially carbonate-based mineral, ike dolomite. Particularly in Aceh province's, the largest dolomite deposits is available in Aceh Tamiang district around 1.9 billion tons. Unfortunately, current use of dolomite in the industry and other applications is still limited. In this work we report the advanced preparation of dolomite using calcinations method. Whereas, with this method, the dolomite mineral can be processed into calcium and magnesium oxide which has a very wide field of application and higher values. To obtain optimal results, we also identify the effect of temperature on the formation of oxide compounds. Preliminary study using XRF founded that dolomite in village Selamat is known as the highest concentration of CaO (61.20% followed by MgO (25.28%. It is also showed that the main phase obtained by XRD is dolomite (CaMg(CO32. Furthermore, after the calcinations process at 700 °C, it was founded that the formation of dolomite were CaCO3 and MgO, whereas at temperatures of 900 °C mostly the CaCO3 has decomposed into CaO. SEM observations showed that dolomite has the composition of particles distributed homogeneously along the particle agglomerate when it calcinations.

X-Ray Fluorescence (XRF) to identify chemical analysis of minerals in Buton island, SE Sulawesi, Indonesia

Science.gov (United States)

Jamaluddin; Darwis, A.; Massinai, M. A.

2018-02-01

Asbuton as natural rock asphalt consists of a granular material; usually limestone or sandstone. In its natural state, it contains bitumen intimately dispersed throughout its mass, while the remainder of the material is a solid mineral matter. This research was conducted in Sorowalio, Buton Regency, Southeast Sulawesi province, Indonesia. This study aims to determine the content and the percentage of minerals contained in the rocks by using X-Ray Fluorescence (XRF). The method of research is a preliminary survey, sampling and laboratory analysis. XRF reports chemical composition, including Si (quartz) and Ca (calcite). The results indicate the content and the percentage of element dominate the rock sample is Fe2O3, MgO, CaO, and SiO2. Research results using XRF show that there are four metal oxide dominant elements. Hematite (Fe2O3) is dominant in all locations of sampling. Magnesium oxide (MgO) has the highest levels found in sample number six and the lowest is in sample number five. Silicates (SiO) has the highest levels at sample number six and the lowest in sample number seven. Calcium oxide (CaO) is dominant in all sampling locations. The sample of asbuton contains 37.90% asphalt, 43.28% carbonate, and18.82% other minerals.

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.

Ion-induced secondary electron emission, optical and hydration resistant behavior of MgO, Mg–Mo–O and Mg–Ce–O thin films

International Nuclear Information System (INIS)

Kumar, Ashok; Thota, Subhash; Deva, Dinesh; Kumar, Jitendra

2014-01-01

Optical transmittance, hydration resistance and secondary electron emission characteristics of e-beam evaporated pure and Mo- or Ce-containing MgO thin films have been investigated. While the increased grain size and pyramidal columnar morphology following incorporation of molybdenum and cerium in MgO are responsible for the excellent discharge characteristics, emergence of neutral {100} and {110} MgO surfaces preferentially give rise to high optical transmittance (∼ 92–100%) and stability against hydration. Further, addition of Mo (or Ce) in MgO causes significant increase in defect density which, in turn, enhances the photoluminescence (PL) emission from 5-, 4- and 3-coordination sites. The changes lead to lowering of the breakdown voltage and hence improvement in the secondary electron emission (SEE) efficiency. These facts have been supported by ion-induced SEE yield (γ) deduced from the a.c. breakdown voltage observed, taking neon as a discharge gas, and determined semi-empirically as well with Hagstrum's theory based on Auger neutralization process using (i) band offset parameters and surface band gap data derived from X-ray photoelectron spectroscopy signal and (ii) information of defect energy levels obtained from photoluminescence (PL) measurements. The experimental values of neon ion-induced SEE yield (γ) are found to be 0.35, 0.42 and 0.39 for MgO, Mg–Mo–O (x = 0.035) and Mg–Ce–O (x = 0.01) thin films, respectively. - Highlights: • Higher hydration resistance • Increased photoluminescence emission • Higher secondary electron emission

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.

Barrier breakdown mechanism in nano-scale perpendicular magnetic tunnel junctions with ultrathin MgO barrier

Science.gov (United States)

Lv, Hua; Leitao, Diana C.; Hou, Zhiwei; Freitas, Paulo P.; Cardoso, Susana; Kämpfe, Thomas; Müller, Johannes; Langer, Juergen; Wrona, Jerzy

2018-05-01

Recently, the perpendicular magnetic tunnel junctions (p-MTJs) arouse great interest because of its unique features in the application of spin-transfer-torque magnetoresistive random access memory (STT-MRAM), such as low switching current density, good thermal stability and high access speed. In this paper, we investigated current induced switching (CIS) in ultrathin MgO barrier p-MTJs with dimension down to 50 nm. We obtained a CIS perpendicular tunnel magnetoresistance (p-TMR) of 123.9% and 7.0 Ω.μm2 resistance area product (RA) with a critical switching density of 1.4×1010 A/m2 in a 300 nm diameter junction. We observe that the extrinsic breakdown mechanism dominates, since the resistance of our p-MTJs decreases gradually with the increasing current. From the statistical analysis of differently sized p-MTJs, we observe that the breakdown voltage (Vb) of 1.4 V is 2 times the switching voltage (Vs) of 0.7 V and the breakdown process exhibits two different breakdown states, unsteady and steady state. Using Simmons' model, we find that the steady state is related with the barrier height of the MgO layer. Furthermore, our study suggests a more efficient method to evaluate the MTJ stability under high bias rather than measuring Vb. In conclusion, we developed well performant p-MTJs for the use in STT-MRAM and demonstrate the mechanism and control of breakdown in nano-scale ultrathin MgO barrier p-MTJs.

X-ray magnetic circular dichroism study of epitaxial magnetite ultrathin film on MgO(100)

Energy Technology Data Exchange (ETDEWEB)

Liu, W. Q.; Xu, Y. B., E-mail: yongbing.xu@york.ac.uk, E-mail: rzhang@nju.edu.cn [York-Nanjing International Center for Spintronics (YNICS), School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); Song, M. Y.; Lin, J. G. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan (China); Maltby, N. J.; Li, S. P. [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); Samant, M. G.; Parkin, S. S. P. [IBM Research Division, Almaden Research Center, San Jose, California 95120 (United States); Bencok, P.; Steadman, Paul; Dobrynin, Alexey [Diamond Light Source, Didcot OX11 0DE (United Kingdom); Zhang, R., E-mail: yongbing.xu@york.ac.uk, E-mail: rzhang@nju.edu.cn [York-Nanjing International Center for Spintronics (YNICS), School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China)

2015-05-07

The spin and orbital magnetic moments of the Fe{sub 3}O{sub 4} epitaxial ultrathin film synthesized by plasma assisted simultaneous oxidization on MgO(100) have been studied with X-ray magnetic circular dichroism. The ultrathin film retains a rather large total magnetic moment, i.e., (2.73 ± 0.15) μ{sub B}/f.u., which is ∼70% of that for the bulk-like Fe{sub 3}O{sub 4}. A significant unquenched orbital moment up to 0.54 ± 0.05 μ{sub B}/f.u. was observed, which could come from the symmetry breaking at the Fe{sub 3}O{sub 4}/MgO interface. Such sizable orbital moment will add capacities to the Fe{sub 3}O{sub 4}-based spintronics devices in the magnetization reversal by the electric field.

Precise microwave characterization of MgO substrates for HTS circuits with superconducting post dielectric resonator

Energy Technology Data Exchange (ETDEWEB)

Mazierska, Janina [Institute of Information Sciences and Technology, Massey University, Palmerston North, P. Bag 11222 (New Zealand); Ledenyov, Dimitri [Electrical and Computer Engineering, James Cook University, Townsville, Q4811 (Australia); Jacob, Mohan V [Electrical and Computer Engineering, James Cook University, Townsville, Q4811 (Australia); Krupka, Jerzy [Instytut Mikroelektroniki i Optoelektroniki Politechniki Warszawskiej, Koszykowa 75, 00-662 Warsaw (Poland)

2005-01-01

Accurate data of complex permittivity of dielectric substrates are needed for efficient design of HTS microwave planar circuits. We have tested MgO substrates from three different manufacturing batches using a dielectric resonator with superconducting parts recently developed for precise microwave characterization of laminar dielectrics at cryogenic temperatures. The measurement fixture has been fabricated using a SrLaAlO{sub 3} post dielectric resonator with DyBa{sub 2}Cu{sub 3}O{sub 7} end plates and silver-plated copper sidewalls to achieve the resolution of loss tangent measurements of 2 x 10{sup -6}. The tested MgO substrates exhibited the average relative permittivity of 9.63 and tan{delta} from 3.7 x 10{sup -7} to 2 x 10{sup -5} at frequency of 10.5 GHz in the temperature range from 14 to 80 K.

Effect of silica sol of different routes on the properties of low cement ...

Indian Academy of Sciences (India)

Unknown

Gravimetric method was utilized to determine SiO2 and Al2O3 whereas Fe2O3,. CaO and MgO were determined volumetrically (Hille- brand and Lundell 1953). It may be seen from table 2 that white fused Al2O3 which is produced from fusion of calcined alumina has a very high purity (99⋅38 wt% Al2O3). Microfine Al2O3.

Geology of volcanogenic massive sulfide deposit near Meli ...

African Journals Online (AJOL)

Bheema

9.96 wt%. Fe2O3, 9.34-9.7 wt% CaO, 8.88-15.72 wt% MgO, 0.69-2.18 wt% Na2O, 1.7-2.31 wt% K2O, 0.29-. 0.81 wt% TiO2, 0.13-0.24 wt% MnO and 0.13-0.64 wt% P2O5. Similarly, intermediate metavolcanic rocks show variation from 60.65- ...

Particle size distribution and physico-chemical composition of clay.

African Journals Online (AJOL)

HP USER

<300µm, <106µm, <63µm and <44µm respectively. There was no remarkable difference in silica (SiO2) as particle fractions reduced from <. 300µm - < 106µm - < 63µm but an observed. Table 1.0 Chemical composition of crude clay. Component wt (%). SiO2. 38.48. Al2O3. 12.46. Fe2O3. 6.18. TiO2. 1.85. MgO. 14.67. CaO.

CHARACTERIZATION OF COMMERCIALLY AVAILABLE ALKALI RESISTANT GLASS FIBER FOR CONCRETE REINFORCEMENT AND CHEMICAL DURABILITY COMPARISON WITH SrO-Mn2O3-Fe2O3-MgO-ZrO2-SiO2 (SMFMZS SYSTEM GLASSES

Directory of Open Access Journals (Sweden)

Göktuğ GÜNKAYA

2012-12-01

Full Text Available According to the relevant literature, the utilization of different kind of glass fibers in concrete introduces positive effect on the mechanical behavior, especially toughness. There are many glassfibers available to reinforce concretes. Glass fiber composition is so important because it may change the properties such as strength, elastic modulus and alkali resistance. Its most important property to be used in concrete is the alkali resistance. Some glasses of SrO–MgO–ZrO2–SiO2 (SMZS quaternary system, such as 26SrO, 20MgO, 14ZrO2, 40SiO2 (Zrn glass, have been found to be highly alkali resistant thanks to their high ZrO2 and MgO contents. Previous researches on these glasses with MnO and/or Fe2O3 partially replacing SrO have been made with the aim of improving the chemical resistance and decreasing the production cost.The main target of the present study, first of all, was to characterize commercially available alkali resistant glass fiber for concrete reinforcement and then to compare its alkali durability with those of the SrO-Mn2O3-Fe2O3-MgO-ZrO2-SiO2 (SMFMZS system glasses. For such purposes, XRF, Tg-DTA, alkali resistance tests and SEM analysis conducted with EDX were employed. According tothe alkali endurance test results it was revealed that some of the SMFMZS system glass powders are 10 times resistant to alkali environments than the commercial glass fibers used in this study.Therefore, they can be considered as alternative filling materials on the evolution of chemically resistant concrete structures.

Iteración de funciones e introducción al caos con Mathematica

OpenAIRE

Rojas, Ángela

2000-01-01

En este trabajo se estudio la iteración de punto fijo muy habitual en todos los programas de calculo numérico y su aplicación en un caso particularmente interesante: la función logística. De esta forma se pueden introducir elementos característicos de la teoría del caos: efecto mariposa o exponente de Lyaponuv, bifurcaciones por duplicación de periodo. Esta experiencia se ha realizado en la escuela de ingeniería técnica de Córdoba, usando Mathematica por la potencia y verticalidad que posee e...

Influence of slag chemistry on the hydration of alkali-activated blast-furnace slag - Part I: Effect of MgO

International Nuclear Information System (INIS)

Ben Haha, M.; Lothenbach, B.; Le Saout, G.; Winnefeld, F.

2011-01-01

The hydration and the microstructure of three alkali activated slags (AAS) with MgO contents between 8 and 13 wt.% are investigated. The slags were hydrated in the presence of two different alkaline activators, NaOH and Na 2 SiO 3 .5H 2 O (WG). Higher MgO content of the slag resulted in a faster reaction and higher compressive strengths during the first days. The formation of C(- A)-S-H and of a hydrotalcite-like phase was observed in all samples by X-ray diffraction (XRD), thermal analysis (TGA) and scanning electron microscopy (SEM) techniques. Increasing the MgO content of the slag from 8 to 13% increased the amount of hydrotalcite and lowered the Al uptake by C-S-H resulting in 9% higher volume of the hydrates and a 50 to 80% increase of the compressive strength after 28 days and longer for WG activated slag pastes. For NaOH activated slags only a slight increase of the compressive strength was measured.

OPTIMASI SUHU REAKSI TRANSESTERIFIKASI PADA MINYAK JERAMI PADI (ORYZA SATIVA L. MENJADI BIODIESEL DENGAN MENGGUNAKAN KATALIS CAO DARI KULIT TELUR AYAM

Directory of Open Access Journals (Sweden)

Tasik Sinta

2016-11-01

Full Text Available The research on optimization of transesterification temperature for production of biodiesel from rice straw oil (Oryza sativa L. using CaO catalyst derived from the chicken egg skin has been conducted. Production of biodiesel was conducted at varied temperatures, namely 30oC, 40oC, 50oC, 60oC and 70oC. The fatty acid compositions of the transesterification products were determined by using GC-MS and the physical and chemical characteristics were determined using SNI Methods 04-7182-2006. The AAS result suggested that the chicken egg skin contained 91.41% CaO. The optimum transesterification temperature was 60oC producing 90,8405% methyl ester. The results of GC-MS showed that the highest percentage of fatty acid was methyl oleic (44.56%.

Ab initio atomistic thermodynamics calculations of the initial deposition of epitaxial MgO film on GaAs(001)-β2(2 × 4)

International Nuclear Information System (INIS)

Tamarany, Rizcky; Lee, Seung-Cheol; Kim, Hyung-Jun; Choi, Jung-Hae

2013-01-01

Ab initio calculations were performed to investigate the initial deposition of epitaxial MgO on GaAs(001)-β2(2 × 4). The differences between the chemical bonding of Mg-As and O-As were characterized by the adsorption energies of atomic O and Mg at several symmetrically distinct sites, and O bonding was substantially stronger than that of Mg. Thermodynamics were analyzed through the introduction of environmental chemical potentials simulating in situ growth conditions by the sputtering of a stoichiometric MgO target. A surface phase diagram was generated under Mg and O environments with constrained equilibrium, and the results explained the initial formation of an epitaxial MgO phase on GaAs(001)-β2(2 × 4).

Effect of Fe2O3 on the sintering and stabilization of ZrO2-MgO system

International Nuclear Information System (INIS)

Longo, E.; Paskocimas, C.A.; Ambrosecchia, J.R.; Weffort, L.C.; Baldo, J.B.; Leite, L.R.; Varela, J.A.

1990-01-01

Through X-ray diffraction, it was studied the influence of the iron oxide (Fe 2 O 3 ) as a mineralizer in the development of partially stabilized zirconia phases (cubic/tetragonal) within the system ZrO 2 -MgO. In the preparation of the studied compositions it was utilized a Brazilian comercial zirconia powder and different precursors for the MgO and Fe 2 O 3 additives. It was observed that the main effect of iron oxide consisted on the speed up of the solid solution formation process of Mg + 2 in the Zr +4 sub-lattice, as well as being a very effective sintering agent. (author) [pt

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.

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

Energy Technology Data Exchange (ETDEWEB)

Stolarz, Anna E-mail: anna@slcj.uw.edu.pl; Maier-Komor, Peter

2002-03-11

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.

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.

Magnesium Oxide (MgO) pH-sensitive Sensing Membrane in Electrolyte-Insulator-Semiconductor Structures with CF4 Plasma Treatment.

Science.gov (United States)

Kao, Chyuan-Haur; Chang, Chia Lung; Su, Wei Ming; Chen, Yu Tzu; Lu, Chien Cheng; Lee, Yu Shan; Hong, Chen Hao; Lin, Chan-Yu; Chen, Hsiang

2017-08-03

Magnesium oxide (MgO) sensing membranes in pH-sensitive electrolyte-insulator-semiconductor structures were fabricated on silicon substrate. To optimize the sensing capability of the membrane, CF 4 plasma was incorporated to improve the material quality of MgO films. Multiple material analyses including FESEM, XRD, AFM, and SIMS indicate that plasma treatment might enhance the crystallization and increase the grain size. Therefore, the sensing behaviors in terms of sensitivity, linearity, hysteresis effects, and drift rates might be improved. MgO-based EIS membranes with CF 4 plasma treatment show promise for future industrial biosensing applications.