检索结果-南通市图书馆

Acta Metallurgica sinica(English Letters) 2013年第5期26卷 509-516页

作者： G.h.Dushaq s.h.mahmood I.Bsoul h.K.Juwhari B.Lahlouh M.A.AlDamen Physics Department The University of Jordan Physics Department Al al-Bayt University Chemistry Department The University of Jordan

Barium hexaferrites BaFe11.6Mox Zn0.4-x O19（x=0.1,0.2,0.4）were prepared by precipitation of the precursors using wet chemical mixture method and then sintering the dried powders at 1100℃.The properties of the prepared samples were investigated using X-ray difraction（XRD）,scanning electron microscopy（sEM）,vibrating sample magnetometer,and Mssbauer *** patterns revealed that all prepared samples had BaFe12O19hexaferrite structure as a majority *** images demonstated that the samples consisted mainly of hexagonal platelet-like grains with diameters ranging from 100 to 500 nm.Mssbauer spectra revealed that Zn2＋ions occupy 4f1 sites leading to the splitting of the 12k *** Mo6＋ions occupy 2b sites while Mo4＋ prefer 4f1 and 12k *** the sample with x=0.4,Mo6＋and Mo4＋ ions were found to have preference for 2b and 12k sites,respectively,and to induce the development of Fe2＋ions in the hexaferrite,leading to noticeable changes in the magnetic properties of the *** observed magnetic properties were found to be consistent with the preferential site occupation of metal ions,and the hyperfine fields derived from Mssbauer spectra of these samples.

关键词： Coercivity Barium hexaferrites Mossbauer spectroscopy Magneticproperties hyperfine Interactions

Low Frequency Electromagnetic Instability in Unmagnetized Inhomogeneous Dusty Plasmas

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2001年第3期18卷 402-404页

作者： s.mahmood Q.haque h.saleem NPD PINsTECh P.O.NiloreIslamabadPakistan

The low frequency electromagnetic wave instability in an unmagetized inhomogeneous dusty plasma has been pointed *** has been noticed that there exists a stable mode if the propagation of the wave vector along the density gradient is ***,the mode becomes unstable by including the propagation of the wave in the opposite direction of the density gradient.

关键词： wave inhomogeneous opposite

Analysis of highly efficient perovskite solar cells with inorganic hole transport material

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第12期28卷 393-399页

作者： I Kabir s A mahmood Department of Electrical and Electronics Engineering Bangladesh University of Engineering and Technology

Organo-halide perovskites in planar heterojunction architecture have shown considerable promise as efficient light harvesters in solar cells. We carry out a numerical modeling of a planar lead based perovskite solar cell(PsC) with Cu2Znsns4(CZTs) as the hole transporting material(hTM) using the one-dimensional solar cell capacitance simulator(sCAPs-1 D). The effects of numerous parameters such as defect density, thickness, and doping density of the absorber layer on the device performance are investigated. The doping densities and electron affinities of the electron transporting material(ETM) and the hTM are also varied to optimize the PsC performance. It has been observed that a thinner absorber layer of220 nm with a defect density of 1014 cm-3 compared to the reference structure improves the device performance. When doping density of the absorber layer increases beyond 2×1016 cm-3, the power conversion efficiency(PCE) reduces due to enhanced recombination rate. The defect density at the absorber/ETM interface reduces the PCE as well. Considering a series resistance of 5 ?·cm2 and all the optimum parameters of absorber, ETM and hTM layers simultaneously, the overall PCE of the device increases significantly. In comparison with the reference structure, the PCE of the optimized device has been increased from 12.76% to 22.7%, and hence the optimized CZTs based PsC is highly efficient.

关键词： Ch3Nh3PbI3 Cu2Znsns4(CZTs) sCAPs-1D absorption coefficient

Investigations of mechanical, electronic, and magnetic properties of non-magnetic MgTe and ferro-magnetic Mg_(0.75)T M_(0.25)Te (TM = Fe, Co, Ni): An ab-initio calculation

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第4期25卷 303-313页

作者： mahmood Q Alay-e-Abbas s M mahmood I Asif mahmood Noor N A Department of Physics University of the Punjab Quaid-e-Azam Campus Department of Physics Government College University Faisalabad Department of Physics University of Sargodha Centre for high Energy Physics University of the Punjab Quaid-e-Azam Campus College of Engineering Chemical Engineering Department King Saud University

The mechanical, electronic and magnetic properties of non-magnetic MgTe and ferro-magnetic （FM） Mgo.75 TM025 Te （TM = Fe, Co, Ni） in the zinc-blende phase are studied by ab-initio calculations for the first time. We use the generalized gradient approximation functional for computing the structural stability, and mechanical properties, while the modified Becke and Johnson local （spin） density approximation （mBJLDA） is utilized for determining the electronic and magnetic properties. By comparing the energies of non-magnetic and FM calculations, we find that the compounds are stable in the FM phase, which is confirmed by their structural stabilities in terms of enthalpy of formation. Detailed descriptions of elastic properties of Mgo.75TMo.25Te alloys in the FM phase are also presented. For electronic properties, the spin- polarized electronic band structures and density of states are computed, showing that these compounds are direct bandgap materials with strong hybridizations of TM 3d states and Te p states. Further, the ferromagnetism is discussed in terms of the Zener free electron model, RKKY model and double exchange model. The charge density contours in the （110） plane are calculated to study bonding properties. The spin exchange splitting and crystal field splitting energies are also calculated. The distribution of electron spin density is employed in computing the magnetic moments appearing at the magnetic sites （Fe, Co, Ni）, as well as at the non-magnetic sites （Mg, Te）. It is found that the p-d hybridization causes not only magnetic moments on the magnetic sites but also induces negligibly small magnetic moments at the non-magnetic sites.

关键词： FP-LAPW + lo elastic parameters spin polarized electronic properties magnetic properties

Insight into generation of induced mesenchymal stem cells from induced pluripotent cells

在线全文

学校读者我要写书评

暂无评论

World Journal of stem Cells 2022年第1期14卷 142-145页

作者： mahmood s Choudhery Ruhma mahmood Department of Biomedical sciences King Edward Medical UniversityLahore 54000PunjabPakistan Department of Genetics and Molecular Biology University of Health SciencesLahore 54600PunjabPakistan stem Cells Laboratory Allama Iqbal Medical CollegeLahore 54000PunjabPakistan

Mesenchymal stem cells(MsCs)have the potential for use in cell-based regenerative ***,hundreds of clinical trials are using MsCs for the treatment of various ***,MsCs are low in number in adult tissues;they show heterogeneity depending upon the cell source and exhibit limited proliferative potential and early senescence in in vitro *** factors negatively impact the regenerative potential of MsCs and therefore restrict their use for clinical *** a result,novel methods to generate induced MsCs(iMsCs)from induced pluripotent stem cells have been *** development and optimization of protocols for generation of iMsCs from induced pluripotent stem cells is necessary to evaluate their regenerative potential in vivo and in *** addition,it is important to compare iMsCs with primary MsCs(isolated from adult tissues)in terms of their safety and *** investigation of the properties of iMsCs in vitro and their long term behavior in animals is important for their translation from bench to bedside.

关键词： Induced mesenchymal stem cells Induced pluripotent stem cells Regenerative potential Pluripotent Multipotent Clinical studies

strategies to improve regenerative potential of mesenchymal stem cells

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of stem Cells 2021年第12期13卷 1845-1862页

作者： mahmood s Choudhery Department of Biomedical sciences King Edward Medical UniversityLahore 54000PunjabPakistan Department of Genetics and Molecular Biology University of Health SciencesLahore 54600PunjabPakistan

In the last few decades,stem cell-based therapies have gained attention worldwide for various diseases and *** stem cells,particularly mesenchymal stem cells(MsCs),are preferred due to their significant regenerative potential in cellular therapies and are currently involved in hundreds of clinical *** MsCs have high self-renewal as well as differentiation potential,such abilities are compromised with“advanced age”and“disease status”of the ***,cell-based therapies require high cell number for clinical applications that often require in vitro expansion of *** is pertinent to note that aged individuals are the main segment of population for stem cell-based therapies,however;autologous use of stem cells for such patients(aged and diseased)does not seem to give optimal results due to their compromised *** vitro expansion to obtain large numbers of cells also negatively affects the regenerative potential of *** is therefore essential to improve the regenerative potential of stem cells compromised due to“in vitro expansion”,“donor age”and“donor disease status”for their successful autologous *** current review has been organized to address the age and disease depleted function of resident adult stem cells,and the strategies to improve their *** combat the problem of decline in the regenerative potential of cells,this review focuses on the strategies that manipulate the cell environment such as hypoxia,heat shock,caloric restriction and preconditioning with different factors.

关键词： hypoxia stem cell aging Growth factors heat shock Caloric restriction

Low Frequency solitary Waves in Magnetized Electron-Positron-Ion Plasmas

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2005年第3期22卷 632-635页

作者： M.Ansarmahmood s.mahmood ArshadM.Mirza h.saleem DepartmentofPhysics Quaid-i-AzamUniversityIslamabad45320Pakistan DepartmentofPhysics COMSATSInstituteofInformationTechnology1-1-8Islamabad45320Pakistan//PINSTECH(PhysicsResearchDivision)P.O.NiloreIslamabad45320Pakistan

Nonlinear electrostatic and electromagnetic low frequency waves are studiedin magnetized electron-positron-ion (EPI) plasmas. The effects of full nonlinearity and threedimensional ion motion have been taken into account. It is shown that both density dips and humpscan coexist in EPI plasmas along with bell-shaped and kink-type solitons. The new results as well asseveral limiting cases for comparison with earlier work have been discussed, for the sake ofcompleteness. Relevance of this work to space, astrophysical and laboratory plasmas is pointed out.

关键词： KINETIC ALFVEN WAVEs

Ab-initio calculations of bandgap tuning of In1-xGaxY(Y=N,P)alloys for optoelectronic applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第11期30卷 467-474页

作者： Muhammad Rashid Jamil M mahmood Q shahid M Ramay Asif mahmood A Ghaithan h M Department of Physics Ghazi University City CampusDera Ghazi Khan32200Pakistan Department of Physics COMSATS University IslamabadIslamabad 44000Pakistan Basic and Applied scientific Research Center(BAsRC) College of Science of DammamImam Abdulrahman Bin Faisal UniversityP.O.Box 383Dammam 31113Saudi Arabia Department Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam 31441Saudi Arabia Physics and Astronomy Department College of ScienceKing Saud UniversityRiyadhSaudi Arabia Chemical Engineering Department College of EngineeringKing Saud UniversityRiyadhSaudi Arabia

The III–V alloys and doping to tune the bandgap for solar cells and other optoelectronic devices has remained a hot topic of research for the last few *** the present article,the bandgap tuning and its influence on optical properties of In1-xGaxN/P,where(x=0.0,0.25,0.50,0.75,and 1.0)alloys are comprehensively analyzed by density functional theory based on full-potential linearized augmented plane wave method(FP-LAPW)and modified Becke and Johnson potentials(TB-mBJ).The direct bandgaps turn from 0.7 eV to 3.44 eV,and 1.41 eV to 2.32 eV for In1-xGaxN/P alloys,which increases their potentials for optoelectronic *** optical properties are discussed such as dielectric constants,refraction,absorption,optical conductivity,and *** light is polarized in the low energy region with minimum *** absorption and optical conduction are maxima in the visible region,and they are shifted into the ultraviolet region by Ga ***,static dielectric constant e1(0)is in line with the bandgap from Penn’s model.

关键词： density functional theory direct bandgap III-V semiconductors tuning of optical band gap solar cell applications

Experimental Investigation of Micro heat Pipes of Different Cross-sections having same hydraulic Diameter

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal science 2008年第3期17卷 247-252页

作者： s.L.mahmood M.A.R.Akhanda Department of Mechanical and Chemical Engineering Islamic University of Technology

Effects of micro heat pipe （MhP） cross-sections and orientations on its thermal performance are experimentally investigated in this study. Tests are conducted using five different cross-sections （circular, semicircular, elliptical, semi-elliptical and rectangular） of micro heat pipes having same hydraulic diameter of 3 rnm placed at three different inclination angles （0°, 45°, 90°）, where water is used as the working fluid. Evaporator section of the MhP is heated by an electric heater and the condenser section is cooled by circulation of water in an annular space between condenser section and the water jacket. Temperatures at different locations of the MhP are measured using five calibrated K type thermocouples. heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the MhP is flattened. Thus among all cross-sections of MhP, circular one exhibits the best thermal performance in terms of heat flux dissipation followed by semi-elliptical, semi-circular, elliptical and rectangular cross-sections. Moreover, its heat transfer capability also decreases with decreasing of its inclination angle. Finally, a correlation is developed which covers all the experimental data within ＋7%.

关键词： Micro heat pipe cross-section hydraulic diameter inclination.

Characterization of vanadyl phthalocyanine based surface-type capacitive humidity sensors

在线全文

学校读者我要写书评

暂无评论

Journal of semiconductors 2010年第11期31卷 9-14页

作者： Fakhra Aziz M.h.sayyad Khassan s.Karimov M.saleem Zubair Ahmad s.mahmood Khan Ghulam Ishaq Khan Institute of Engineering sciences and Technology Topi-23640Pakistan Low Dimensional Material Research Center Department of PhysicsUniversity of Malaya50603 Kuala LumpurMalaysia Physical Technical Institute Aini St-299/1Dushanbe734063Tajikistan Department of Mechanical Engineering 20 Symonds Street AucklandUniversity of AucklandNew Zealand

This study presents the fabrication and characterization of novel surface-type capacitive humidity sensors using vanadyl phthalocyanine（VOPc） as the active *** devices,which comprise three different thicknesses, have been fabricated using the thermal evaporation technique.A thin film of VOPc is deposited on thoroughly cleaned glass substrates with pre-patterned Ag *** capacitive effect of the samples under humidity has been investigated. Comparison of the samples with different thicknesses shows that the thinnest device seems more sensitive towards *** humidity dependent capacitance properties of the sensor make it beneficial for use in commercial hygrometers.

关键词： surface-type capacitance vanadyl phthalocyanine humidity sensor organic semiconductor