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Progress in Natural Science:materials International 2019年第2期29卷 198-209页

作者： h.Felhi m.Smari A.Bajorek K.Nouri e.Dhahri L.Bessais Applied Physics Laboratory Sfax Faculty of Sciences University of Sfax Center for Functionalized magnetic materials (Funmagma) Immanuel Kant Baltic Federal University A.Che?kowski Institute of Physics University of Silesia in Katowice Silesian Center for education and Interdisciplinary Research University of Silesia in Katowice CmTR ICMPE UMR 7182 CNRS-UPEC

In this work, a novel series of multiferroic materials Bimn2O5doped by Neodyme has been prepared by a sol-gel method at low temperature. The crystallographic studies using X-ray diffraction and Rietveld Refinement techniques showed the formation of single-phase samples for all compositions, crystallizing in a mullite-type orthorhombic perovskite structure, space group Pbam(Z = 4). The Sem techniques confirmed the formation of single-phase materials with excellent mapping distribution. Raman and infrared spectroscopic measurements were performed and combined with lattice dynamics simulations to describe the room-temperature vibrational properties of all samples. The X-ray Photoelectron Spectroscopy(XPS) were measured in the energy range of 0–1400 eV at room temperature. The Fermi level eFwas defined with the accuracy of 0.127, 0.32 and 0.48 eV for Bimn2O5, Bi0.9Nd0.1mn2O5and Bi0.8Nd0.2mn2O5respectively. The X-ray photoelectron spectroscopy shows the existence of mn4+state. magnetic measurements indicate Neél temperature TNat 31, 40 and 61 K for Bimn2O5,Bi0.9Nd0.1mn2O5and Bi0.8Nd0.2mn2O5respectively.

关键词： multiferroics X-ray photoelectron spectroscopy Fermi level magnetic properties

Ultrafast magneto-optical dynamics in nickel(111)single crystal studied by the integration of ultrafast reflectivity and polarimetry probes

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Chinese Physics B 2024年第3期33卷 65-69页

作者：匡皓余军潇陈洁 h.e.elsayed-Ali 李润泽 Peter m.Rentzepis School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Center for Transformative Science ShanghaiTech UniversityShanghai 201210China Center for Ultrafast Science and Technology Key Laboratory for Laser Plasmas (Ministry of Education)Collaborative Innovation Center of IFSA (CICIFSA)School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Department of electrical and Computer engineering Old Dominion UniversityNorfolkVirginia 23529USA Department of electrical and Computer engineering Texas A&M UniversityCollege StationTexas 77843USA

With the integration of ultrafast reflectivity and polarimetry probes,we observed carrier relaxation and spin dynamics induced by ultrafast laser excitation of Ni(111)single *** carrier relaxation time within the linear excitation range reveals that electron-phonon coupling and dissipation of photon energy into the bulk of the crystal take tens of *** the other hand,the observed spin dynamics indicate a longer time of about 120 *** further understand how the lattice degree of freedom is coupled with these dynamics may require the integration of an ultrafast diffraction probe.

关键词： ultrafast spin dynamics non-equilibrium dynamics multi-probe

The synergetic effects of two CCAAT boxes in Aspergillus niger glaA gene promoter on activation of PglaA transcription

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Science China(Life Sciences) 2004年第2期47卷 139-147页

作者： WANG h. m. Genencor International Inc. 925 Page Mill Road Palo Alto California 94304 USA

emSA and footprinting analyses have revealed that the -489—-414 bp and the -390—-345 bp (designated DC and PC respectively) upstream of the Aspergillus niger T21 glaA gene were bound by one protein factor in the A. niger T21 whole cell extract. Both DC and PC contained CCAAT pentanucleotides. The functions of DC and PC in regulation of expression of glucoamylase (GLA) were studied. CCAAT pentanucleotides were replaced with CGTAA and the mutated DNA fragments DCm and PCm lost the binding activities of protein factors in vitro. In vivo when either DC or PC was mutated or the relative orientations between them were changed on the PglaA, the transcriptional activity of PglaA decreased to a basal level. Introduction of multi-copies of DC into the original site at the PglaA in A. niger T21 decreased the expression of endogenous GLA expression and the exogenous reporter e. coli uidA gene introduced under the PglaA promoter, while having no effect on the uidA gene under the control of PgpdA. emSA re-vealed that the levels of the specific DNA-binding protein factors in the transformants maintained the same meaning that introduction of multi-copies of DC caused the titration effect. AnghapC gene was cloned from A. niger T21 cDNA and introduced into the DC multi-copied strains. The expression of AnghapC improved the expression of the endogenous GLA and the exogenous gene controlled by PglaA. These results showed that both the CCAAT pentanucleotides were necessary for DC and PC binding to the protein factors, and the simultaneous binding of DC and PC to the protein was necessary for promoting the transcriptional activity of PglaA. AnghapC was the specific positive trans-acting protein factor binding to DC.

关键词： Aspergillus niger glucoamylase, synergetic effect, mutation analysis, multi-copy of CCAAT box, titration effect.

mechanical Behavior of Crmo4 Steel With Dual-Phase microstructure

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Journal of Iron and Steel Research International 2011年第S1期18卷 862-868页

作者： A Salemi A-h Golestaneh e moosavi-Khoonsari Department of metallurgy engineering Islamic Azad University-Karaj BranchKarajIran Noor Behineh Gostar Co.Ltd.Tehran Iran

multi-phase microstructures having good ductility may replace the conventional microstructures in different technological applications such as pressure *** properties including the fracture behavior and the service life of pressure vessels are strongly affected by the *** objective of this study was to investigate the correlation between different dual-phase microstructures and mechanical properties of 42Crmo4 (AISI 4140) *** produce the martensite-bainite (m-B),the martensite-ferrite (m-F),and the ferrite-bainite (F-B) microstructures,the step quenching heat treatment was *** properties of heat treated samples including the strength,ductility,and impact energy were *** experiments revealed a discontinuous yielding in the F-B specimen with ferritic ***\graphic results showed high concentration bright facets (BFs) on broken specimen surfaces indicating the brittle cleavage fracture was the predominant mechanism in the dual-phase microstructures.

关键词： 42Crmo4 steel dual-phase microstructures cleavage fracture

Preparation and Properties of Some Chemical and electrochemical γ-mnO_2

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Journal of materials Science & Technology 2001年第3期17卷 351-354页

作者： h.m.Abbas, Kh. S.Abou-el-Sherbini, m.h.Askar and A. m. hashim Dept.of Physical Centre, National Research Centre, Tahiu, Dokki, Cairo, egypt e-mail: sherbini@*** Dept. of Phys. Cent. Natl. Res. Cent. Cairo Egypt

Chemically prepared electrolytic 2-mn02 and an electrodeposited mnO2 doped with Ce(Ⅲ) were subjected to physicochemical studies. X-ray diffractometry, density measurements, chem-ical analysis and thermal analysis were used to determine the structure and chemical disorder present. The samples prepared chemically (CmD) or electrochemically (emD) showed a variable amount of de Wolff disorder (Pr) and microtwinning (Tw). manganese dioxide prepared in the presence of Ce(Ⅲ) showed appreciable decrease in de Wolff defect and a large amount of microtwinning. Thermal analysis showed a loss of weight due to the physically adsorbed and the structural (Oh) water, from which the activation energy was calculated. Chemical composition and formulae calculated on the bases of cation vacancy model, cleared that Ce(lIl)-doped sample has a remarkable increase in the vacancies population associated with higher structural water content. This leads to lower activation energy of water release, and consequently it is supposed to acquire higher electrochemical activity.

关键词： emD mnO2

Institutional arrangement and typology of community forests of meghalaya, mizoram and Nagaland of North-east India

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Journal of Forestry Research 2013年第1期24卷 179-186页

作者： B. K. Tiwari h. Tynsong m. m. Lynrah e. Lapasam S. Deb D. Sharma Department of environmental Studies North-Eastern Hill University Regional Centre National Afforestation and Eco-Development BoardNorth-Eastern Hill University

most community forests in hill regions of northeast India have been managed by traditional local institutions for centuries and most of these institutions remain functional even today. higher forest coverage on private and community lands as compared to government land indicates that traditional institutions effectively manage community forests in the region. The present study was conducted through a survey of literature and field work using participatory research tools viz., PRA exercises, group discussions and questionnaire interviews with key informants in northeast India. We categorized the institutions involved in conservation and management of forests into three major types： traditional, quasi-traditional and modern. Traditional institutions with hierarchal structure were found in all states and are intact and functional in the state of meghalaya. Quasi-traditional institutions, a blend of traditional and modern institutions were prevalent in Nagaland while modern institutions have almost replaced traditional institutions in mizoram. We recorded at least eleven types of community forests viz., group of village forest, village forest, restricted forest, sacred forest, clan forest, cemetery forest, regeneration forest, bamboo forest, recreation forest, village reserved forest and medicinal plantation in villages of three states. The tribal people, through long-term trial and error experiments, have developed an elaborate, functional and generally democratic system of conservation and management of forests and associated natural ecosystems. Several forest and natural resource management lessons can be learnt from the institutional structure and decision making system of the evolving and dynamic institutions of tribal communities of the region.

关键词： sustainable natural resources community, institution: tribal

Combustion Synthesis of Ti-2B-Cu/Ni and 3Ti-2BN-Cu/Ni Bilayered Cermets

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Journal of materials Science & Technology 2003年第4期19卷 355-359页

作者： WeipingSheN WenbinCAO ChangchunGe e.h.Grigoryan A.e.Sytschev A.S.Rogachev Lab.ofSpecialCeramics&P/m UniversityofScienceandTechnologyBeijingBeijing100083China InstituteofStructuremacrokinetics RussianAcademyofSciencesChernogolovka142432Russia

The effects of Cu and Ni (x=0, 10, 20 and 40 wt pet) and compaction pressures (12, 24, 84 and 108 mPa) on combustion wave velocity and wave front shape for Ti-2B-Cu/Ni and 3Ti-2BN-Cu/Ni bilayered cermets were investigated by a video camera. Since the boiling point of Cu is lower, the wave velocities of specimens are slower. Due to the higher specific heat of Ni than that of Cu, the wave velocities of specimens was slowed down a lot with increasing the Ni diluent. The wave velocity differences of the specimens containing Ni are more than that of the bilayered specimens containing Cu. Wave velocities of the specimens containing Ni increased more than that of the specimens containing Cu when higher pressure was employed for green mixture. The more the wave velocity difference of the bilayer, the more curved the specimen.

关键词： Combustion synthesis Functionally graded material Cermet

effect of Cu-ZnO-Al_2O_3 supported on h-ferrierite on hydrocarbons formation from CO hydrogenation

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Chinese Journal of Catalysis 2016年第3期37卷 378-388页

作者： J.h.Flores m.e.h.maia da Costa m.I.Pais da Silva 里约热内卢天主教大学生物化学系里约热内卢天主教大学物理系

methanol synthesis catalysts based on Cu, Zn and Al were prepared by three methods and subsequently mixed with h-ferrierite zeolite in an aqueous suspension to disperse the catalysts over the support. These materials were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, temperature programmed reduction, Nh3 and h2 temperature-programmed desorption, and X-ray photoelectron spectroscopy. They were also applied to the CO hydrogenation reaction to produce dimethyl ether and hydrocarbons. The catalysts were prepared by coprecipitation under low and high supersaturation conditions and by a homogeneous precipitation method. The preparation technique was found to affect the precursor structural characteristics, such as purity and crystallinity, as well as the particle size distribution of the resulting catalyst. Low supersaturation conditions favored high dispersion of the Cu species, increasing the methanol synthesis catalyst＇s metallic surface area and resulting in a homogeneous particle size distribution. These effects in turn were found to modify the zeolite properties, promoting both a low micropore volume and blockage of the zeolite acid sites. The effect of the methanol synthesis catalyst on the reaction was verified by the correlation between the Cu surface area and the CO conversion rate.

关键词： methanol synthesis catalyst Low supersaturation precipitation high supersaturation precipitation Syngas hydrotalcite hydrocarbon Dimethyl ether

mechanism of fracture in macro- and micro-scales in hollow centre cracked disc specimen

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Journal of Central South University 2015年第11期22卷 4426-4433页

作者： m.eftekhari A.Baghbanan h.hashemolhosseini h.Amrollahi Department of mining engineering Isfahan University of Technology (IUT)

The hollow centre cracked disc(hCCD) specimen is one of the suggested alternative methods for determining the fracture toughness of rock. This work aims to investigate the fracture mechanism in hCCD in macro- and micro-scales using numerical methods, extended finite element method(X-Fem) and particle flow code(PFC) modeling, respectively. In the X-Fem, heaviside and near-tip enrichment functions are employed to consider the presence of the crack in the model. In PFC modeling the movement and interaction of stressed assemblies of rigid spherical particles are modeled using the distinct element method(Dem). A numerical code called meX-Fem based on XFem has been developed to simulate the problems involving crack. The models of pure modes I and Ⅱ in macro-scale are simulated in micro-scale. The results show that dimensionless stress intensity factors(YI, YⅡ) for pure modes I and Ⅱ increase by increasing the crack length ratio. The angle at which the pure mode Ⅱ occurs decreases by increasing the crack length ratio. In mixed mode I-Ⅱ, The value of YI decreases by increasing the crack angle, while the value of YⅡ increases to a given crack angle and then it decreases. moreover, the fracture in micro-scale, unlike the macro-scale, includes a combination of different modes of fracturing.

关键词： hollow centre cracked disc(hCCD) extended finite e

Numerical Analysis of mhD Accelerator with Non-equilibrium Air Plasma

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Plasma Science and Technology 2012年第12期14卷 1110-1115页

作者： m.ANWARI h.h.QAZI SUKARSAN N.hARADA electrical engineering Department Umm Al-Qura University Faculty of electrical engineering Universiti Teknologi Malaysia Faculty of electrical engineering Universitas Islam "45" Bekasi Department of electrical engineering Nagaoka University of Technology

magnetohydrodynamic （mhD） accelerator is proposed as a next generation propulsion system. It can be used to increase the performance of a propulsion system. The objective of this study is to investigate the performance of mhD accelerator using non-equilibrium air plasma as working gas. In this study, the fundamental performance of mhD accelerator such as flow performance and electrical performance is evaluated at different levels of applied magnetic field using I-D numerical simulation. The numerical simulation is developed based on a set of differential equations with mhD approximation. To solve this set of differential equations the macCormack scheme is used. A specified channel designed and developed at NASA marshall Space Flight Centre is used in the numerical simulation. The composition of the simulated air plasma consists of seven species, namely, N2, N, O2, O, NO, NO＋, and e-. The performance of the non-equilibrium mhD accelerator is also compared with the equilibrium mhD accelerator.

关键词： mhD accelerator Faraday type connection non-equilibrium air plasma