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Study of Sintering Behaviour and Electrical Conductivity of Cr-Zn-Fe-O System

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Journal of materials Science & Technology 1999年第1期15卷 79-82页

作者： hanna, A.A. khalil, m.sh. saleh, h.i. Ali, A.F. inorganic Chemistry Department National Research Centre Dokki Cairo Egypt

A series of chemical composition based on Cr, Fe and O with Zn as a partially substituting ion has been prepared in the general formula Zn//xCr//1// minus //xFe//2O by coprecipitation method using Nh//4Oh as the precipitating agent at ph equals 10.3. The prepared samples were identified by both thermal analysis (DTA and TGA) and X-ray diffraction. it was found that no single phase is obtained for any of the studied compositions but a mixture of different phases is observed, depending on the molar percentage of zinc ion substitution as well as on the sintering temperature. The temperature dependence of the electrical conductivity, sigma , of the prepared samples is plotted between 25 and 680 degree C. it was observed that the electrical conductivity increases with temperature for both samples with x equals 0.00 and 0.80 Zn ion content while it is nearly temperature independent for samples with.intermediate Zn concentration x equals 0.2 and 0.5 mol fraction. The activation energy, E//a, calculated from the linear relation, lg sigma -1000/T for the final mixtures (sintered at 1300 degree C) was calculated. (Edited author abstract) 16 Refs.

关键词： Chromium compounds

Buoyant marangoni convection of nanofluids in square cavity

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Applied mathematics and mechanics(English Edition) 2015年第9期36卷 1169-1184页

作者： h.saleh i.hAshim School of mathematical Sciences Universiti Kebangsaan Malaysia Solar Energy Research.institute Universiti Kebangsaan Malaysia Research.institute Center for Modeling & Computer Simulation(RI/CM&CS)King Fahd University of Petroleum & Minerals

The buoyant marangoni convection heat transfer in a differentially heated cavity is numerically studied. The cavity is filled with water-Ag, water-Cu, water-Al2O3, and water-TiO2 nanofiuids. The governing equations are based on the equations involving the stream function, vorticity, and temperature. The dimensionless forms of the governing equations are solved by the finite difference （FD） scheme consisting of the alternating direction implicit （ADi） method and the tri-diagonal matrix algorithm （TDmA）. it is found that the increase in the nanoparticle concentration leads to the decrease in the flow rates in the secondary cells when the convective thermocapillary and the buoyancy force have similar strength. A critical marangoni number exists, below which.increasing the marangoni number decreases the average Nusselt number, and above which.increasing the marangoni number increases the average Nusselt number. The nanoparticles play a crucial role in the critical marangoni number.

关键词： finite difference method marangoni convection nanofluid

Flow Reversal of Fully-Developed mixed mhD Convection in Vertical Channels

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Chinese Physics Letters 2010年第2期27卷 138-140页

作者： h. saleh, i. hashim Centre for modelling and Data Analysis School of Mathematical Sciences Universiti Kebangsaan Malaysia 43600 UKM Bangi Selangor Malaysia

The present analysis is concerned with flow reversal phenomena of the fully-developed laminar combined free and forced mhD convection in a vertical parallel-plate channel. The effect of viscous dissipation is taken into account. Flow reversal adjacent to the cold （or hot） wall is found to exist within the channel as Gr/Re is above （or below） a threshold value. Parameter zones for the occurrence of reversed flow are presented.

关键词： Chinese climate network complex systems small world community

The sexually dimorphic expression of glutamate transporters and th.ir implication in pain after spinal cord injury

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Neural Regeneration Research 2025年第11期20卷 3317-3329页

作者： Jennifer m.Colón-mercado Aranza i.Torrado-Tapias iris K.Salgado Jose m.Santiago Samuel E.Ocasio Rivera Dina P.Bracho-Rincon Luis h.Pagan Rivera Jorge D.miranda Department of Physiology University of Puerto RicoMedical Sciences CampusSan JuanPRUSA National institutes of health National Human Genome Research InstituteBethesdaMDUSA Universidad Central del Caribe School of MedicineBayamónPRUSA University of Puerto Rico Carolina CampusCarolinaPRUSA institute of Neurobiology San JuanPRUSA

in addition to the loss of motor function,~60% of patients develop pain after spinal cord *** cellular-molecular mechanisms are not well understood,but the data suggests that plasticity within the rostral,epicenter,and caudal penumbra of the injury site initiates a cellularmolecular interplay that acts as a rewiring mechanism leading to central neuropathic *** can lead to the formation of new connections triggering abnormal sensory *** excitatory glutamate transporters are responsible for the reuptake of extracellular glutamate which makes them a critical target to prevent neuronal hyperexcitability and *** previous studies showed a sexually dimorphic therapeutic window for spinal cord injury after treatment with the selective estrogen receptor modulator *** this study,we investigated the anti-allodynic effects of tamoxifen in male and female rats with spinal cord *** hypothesized that tamoxifen exerts anti-allodynic effects by increasing the expression of glutamate transporters,leading to reduced hyperexcitability of the secondary neuron or by decreasing aberrant *** and female rats received a moderate contusion to the thoracic spinal cord followed by subcutaneous slow-release treatment of tamoxifen or matrix pellets as a control(placebo).We used von Frey monofilaments and the“up-down method”to evaluate mechanical *** treatment decreased allodynia only in female rats with spinal cord injury revealing a sexdependent *** expression profile of glutamatergic transporters(excitatory amino acid transporter 1/glutamate aspartate transporter and excitatory amino acid transporter 2/glutamate transporter-1)revealed a sexual dimorphism in the rostral,epicenter,and caudal areas of the spinal cord with a pattern of expression primarily on *** rodents showed a significantly higher level of excitatory amino acid transporter-1 expression while male rodents showed increased

关键词： allodynia central neuropathic pain EAAT-1/GLAST EAAT-2/GLT-1 glutamate transporters selective estrogen receptor modulator sexual dimorphism spinal cord injury trauma

Electrical Conductivity and infra Red of CaTiO_3 Doped with CuO

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Journal of materials Science & Technology 2001年第6期17卷 667-669页

作者： F.F.hammad and m.sh.khalil Department of inorganic Chemistry, National Research Centre, Dokki, Cairo, Egypt A. h. Salama Department of Physical Chemistry, National Research Centre, Dokki, Cairo, Egypt [manuscript rece Natl Res Ctr Dept Inorgan Chem Cairo Egypt Natl Res Ctr Dept Phys Chem Cairo Egypt

The electrical conductivity of pure CaTiO3 and that containing 0.5~5.0 mole fraction CuO as dopant were measured in the temperature range 291~773 K. The conductivity values varied as a function of temperature and dopant concentration. The activation energy in the lower temper- ature range depended on the impurity content while in the high temperature range it indicated a value of energy gap width. The infrared absorption spectra in the range of 100~4000 cm-1 revealed the presence of two main bands at 340 and 570 cm-1 which were assigned to Ti06 oc- tahedral normal mode. Bands in the range of 106~270 cm-1 were due to the vibration of anion TiO3-2. Some bands were observed at higher values due to the presence of lattice imperfections. There was a slight shift in band position with.increasing dopant concentration which favors the formation of orthorhombic modification.

关键词： Electrical Conductivity and infra Red of CaTiO3 Doped with CuO TiO in

inverse heat Transfer Problem of Thermal Contact Conductance Estimation in Periodically Contacting Surfaces

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Journal of Thermal Science 2009年第2期18卷 150-159页

作者： m.h.shojaeefard K.Goudarzi m.sh.mazidi Dept. of mechanical Engineering Iran University of Science and Technology

The problems involving periodic contacting surfaces have different practical applications. An inverse heat conductionproblem for estimating the periodic Thermal Contact Conductance (TCC) between one-dimensional, constantproperty contacting solids has been investigated with conjugate gradient method (CGm) of function *** method converges very rapidly and is not so sensitive to the measurement errors. The advantage of thepresent method is that no a priori information is needed on the variation of the unknown quantities, since the solutionautomatically determines the functional form over the specified domain. A simple, straight forward tech.iqueis utilized to solve the direct, sensitivity and adjoint problems, in order to overcome the difficulties associatedwith numerical methods. Two general classes of results, the results obtained by applying inexact simulatedmeasured data and the results obtained by using data taken from an actual experiment are presented. in addition,extrapolation method is applied to obtain actual results. Generally, the present method effectively improves theexact TCC when exact and inexact simulated measurements input to the analysis. Furthermore, the results obtainedwith CGm and the extrapolation results are in agreement and the little deviations can be negligible.

关键词： thermal contact inverse problem conjugates gradient method

Junction properties and conduction mechanism of new terbium complexes with triethylene glycol ligand for potential application in organic electronic device

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Journal of Rare Earths 2014年第7期32卷 633-640页

作者： N.K.Za’aba m.A.mohd Sarjidan W.h.Abd.majid Eny Kusrini muhammad i.saleh Low Dimensional materials Research Centre Physics DepartmentUniversity Malaya Department of Chemical Engineering Faculty of EngineeringUniversitas Indonesia School of Chemical Sciences Universiti Sains Malaysia

Terbium-picrate triethylene glycol（EO3-Tb-Pic） complex was prepared in thin film and single layer device structure of iTO/EO3-Tb-Pic/Al, using spin coating tech.ique. The UV-Vis absorption spectroscopy analysis was performed to evaluate the electronic molecular transition of the complex. The optical band gap, Eg estimated from the Tauc model revealed that EO3-Tb-Pic thin film exhibited a direct transition with Eg of 2.70 eV. The electronic parameters of the iTO/EO3-Tb-Pic/Al device such as the ideality factor n, barrier h.ight Φb, saturation current io, and series resistance Rs, were extracted from the conventional lni-V, Cheung＇s functions and Norde＇s method. it was found that the evaluated parameters calculated from Norde＇s and Cheung＇s methods were consistent with those calculated from the conventional i-V method. in the double logarith.ic i-V plot, three distinct regions based on the slope were identified, and the conduction mechanisms were discussed and explained. The mobility, μ value was estimated from SCLC region as 2.58×10^–7 cm2/（V·s）. This newly obtained lanthanide complex may be potentially utilized in electronic devices.

关键词： terbium-picrate complex triethylene glycol Tauc model optical band gap current-voltage rare earths

Studies on Progressive Reactions Leading Formations of Different Types of Barium Ferrites

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Journal of materials Science & Technology 1999年第2期15卷 159-163页

作者： h.i.saleh(inorganic Chemistry Department, National Research Centre, Dokki-12311, Cairo, Egypt) inorganic Chemistry Department National Research Centre Dokki-12311 Cairo Egypt

The present investigation is concerned with the reaction of barium and iron nitrates mixtures using three different molar ratios, 1:1 (Ⅰ), 1:2 (Ⅱ) and 2:1 (Ⅲ) at different temperatures as pointed out from the DTA data. The reaction products exhibit 12 compounds namely, Ba(NO3)2, αFe2O3, Fe3O4, BaFeO3, BaFeO2.9, hexagonal BaFeO3-x, tetragonal BaFeO3-x, BaFe2O4, αBaFe2O4, Ba2Fe6O11, Ba5Fe14O26 and BaFe12O19. The formation of these products depend on the molar ratio between the reactants and the reaction temperature. The reaction products were studied by DTA and TG tech.iques and characterized by X-ray diffraction patterns, magnetic susceptibility data and scanning electron microscopy, SEm.

关键词： Ba Studies on Progressive Reactions Leading Formations of Different Types of Barium Ferrites OO

Sorption of certain lanthanides by kieselguhr loaded with Cyanex 572 from sulfate medium

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Journal of Rare Earths 2020年第3期38卷 299-305页

作者： sh.sh.Emam m.S.Gasser N.E.El-hefny W.h.mahmoud h.F.Aly hot Laboratories Centre Atomic Energy AuthorityCairo 13759Egypt Department of Chemistry Faculty of ScienceAin Shams UniversityCairoEgypt

Kieselguhr for chromatography was loaded with Cyanex 572 extractant and characterized using X-ray diffraction(XRF),scanning electron microscopy(SEm),Fourier transform infra-red(FT-iR),and thermal *** of some heavy lanthanides together with yttrium by the prepared kieselguhr/Cy-572 sorbent was investigated by batch experiment in terms of initial metal ions concentrations,volume to solid mass ratio(V/m),sulfuric acid concentration as well as *** sorption equilibrium of Cy-572 loaded kieselguhr was satisfactorily explained by the pseudo second-order kinetic model and Langmuir isotherm ***,the values of thermodynamic parameters △G°,△h°,and △S°at25℃of the studied metal ions show that the process is spontaneous and endothermic in nature.2.0 mol/L hNO3 is promising to desorb these metal ions.

关键词： Sorption Cyanex 572 Lanthanides Kieselguhr Sulfate medium Rare earths