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Quantum spin hall and quantum valley hall effects in trilayer graphene and their topological structures

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Chinese Physics B 2017年第12期26卷 481-490页

作者： majeed Ur Rehman A A Abid ICQD Hefei National Laboratory for Physical Sciences at Microscale Department of Physics University of Science and Technology of China Hefei 230026 China Key Laboratory of Geospace Environment(Chinese Academy of Sciences) Department of Geophysics and Planetary Science University of Science and Technology of China Hefei 230026 China

The present study pertains to the trilayer graphene in the presence of spin orbit coupling to probe the quantum spin/valley hall effect. The spin Chern-number Cs for energy-bands of trilayer graphene having the essence of intrinsic spin-orbit coupling is analytically calculated. We find that for each valley and spin, Cs is three times larger in trilayer graphene as compared to single layer graphene. Since the spin Chern-number corresponds to the number of edge states, consequently the trilayer graphene has edge states, three times more in comparison to single layer graphene. We also study the trilayer graphene in the presence of both electric-field and intrinsic spin-orbit coupling and investigate that the trilayer graphene goes through a phase transition from a quantum spin hall state to a quantum valley hall state when the strength of the electric field exceeds the intrinsic spin coupling strength. The robustness of the associated topological bulk-state of the trilayer graphene is evaluated by adding various perturbations such as Rashba spin-orbit （RSO） interaction αR, and exchange-magnetization M. In addition, we consider a theoretical model, where only one of the outer layers in trilayer graphene has the essence of intrinsic spin-orbit coupling, while the other two layers have zero intrinsic spin-orbit coupling. Although the first Chern number is non-zero for individual valleys of trilayer graphene in this model, however, we find that the system cannot be regarded as a topological insulator because the system as a whole is not gaped.

关键词： trilayer graphene quantum spin hall effect topological insulator quantum phase transition

Biodiesel synthesis via metal oxides and metal chlorides catalysis from marine alga Melanothamnus afaqhusainii

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Chinese Journal of Chemical Engineering 2016年第3期24卷 388-393页

作者： Abdul majeed Khan Noureen Fatima Research Laboratory of Bioenergy Department of ChemistryFederal Urdu University of ArtsSdence and TechnologyCulshan-e-lqbal CampusUniversity RoadKarachi-75300Pakistan

This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus alhqhusainii. CaO was found to be the most reactive metal oxide that yielded 80% biodiesel while ZnCI2 was the most reactive metal chloride that produced 60% biodiesel by mechanical stirring for 6 h at 100-110 ℃. The overall reactivity order of the catalysts was found to be CaO 〉 MgO 〉 Pb02 〉 ZnC12 〉 TIC14 〉 PbO 〉 hgC12 〉 ZnO 〉 AIC13 〉 SnCI2 〉 TiO2 whereas, CaCI2, MgCI2, A1203, hgO, PbCI2, MnO2, MnC12, Fe203 and FeCI3 were found to be non-reactive for transesterification of triglycerides. In addition, a detailed study of the screening of mobile phases and spraying reagents was conducted which showed that petroleum ether ： chloroform ： toluene （7：2：1 ） is the best mobile phase, whereas iodine crystals/silica gel is the best visualizing agent for the thin layer chroma- tography （TLC） examination ofbiodiesel. Biodiesel production was confirmed by comparative TLC examination. It was further supported by the determination of fuel properties of biodiesel, which were found to be similar to the standard limits of American Society for Testing and Materials （ASTM）,

关键词： Biomass Methanolysis Triglycerides Biodiesel Catalysts

Dipole and Quadrupole Electroexcitations of the Isovector T = 1 Particle-hole States in ^12C

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Chinese Physics Letters 2006年第10期23卷 2699-2702页

作者： F.A.majeed R.A.Radhi Instituto de Fisica Universidade Federal do Rio de Janeiro C.P. 68528 21941-972 Rio de Janeiro RJ Brazil Department of Physics College of Science Baghdad University Baghdad IRAQ

Electroexcitations of the dominantly T=1 particle-hole states of ILC are studied in the framework of the harmonic oscillator shell model. All possible T=1 single-particle-hole states of all allowed angular momenta are considered in a basis including single-particle states up to the 1f-2p shell. The hamiltonian is diagonalized in this space in the presence of the modified surface delta interaction. Correlation in the ground state wavefunctions by mixing more than one configuration is considered and shows a major contribution that leads to enhance the calculations of the form factors. A comparison with the experiment shows that this model is able to fit the location of states and a simple scaling of the results give a good fit to the experimental form factors.

关键词： Ground state

Vegetative propagation ofAesculus indica through stem cuttings treated with plant growth regulators

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Journal of Forestry Research 2009年第A2期20卷 171-173,I0004页

作者： Mumtaz majeed M.A. Khan A.h.Mughal Faculty of Forestry Sher-e-Kashmir University of Agricultural Science ＆ Technology Shalimar Srinagar- 191 121 J＆K lndia

Cuttage propagation of Aesculus indica was tested by treatments with different concentrations of indole-3-acetic acid （IAA） @ 2000, 4000 （ppm）, indolebutyric acid （IBA） @ 2000, 4000 （ppm） and naphthlcetic acid （NAA） @ 2000, 4000 （ppm） in dry formulation in the Forest Nursery, Faculty of Forestry, SKUAST-K, Shalimar. The cuttings treated with IBA @ 4000 ppm and IBA @ 2000 ppm had a sprouting rate of 75% and 50%, respectively, which was significantly higher than that of control and other treatments. The highest rooting rate （50%） was recorded in the cuttings with the application of IBA @ 4000 ppm. The cuttings treated with IBA @ 2000 ppm had 25% rooting rate. All other treatments along with control （talc powder） failed to induce rooting. It was concluded that IBA @ 4000 ppm was a better-applied concentration for vegetative propagation ofA. indica under Kashmir conditions.

关键词： Aesculus indica indolebutyric acid rootingi stem cuttings vegetative propagation

Teleparallel Killing Vectors of Spherically Symmetric Spacetimes

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Communications in Theoretical Physics 2009年第9期52卷 435-440页

作者： M.Sharif Bushra majeed Department of Mathematics University of the Punjab

In this paper, Killing vectors of spherically spacetimes have been evaluated in the context of teleparallel theory of gravitation. Further, we investigate the Killing vectors of the Friedmann metrics. It is found that for static spherically spacetimes the number of Killing vectors turns out to be seven while for the Friedmann models, we obtain six teleparallel Killing vectors. The results are then compared with those of General Relativity. We conclude that both of these descriptions of gravity do not provide the consistent results in general. however, these results may coincide under certain conditions for a particular spacetime.

关键词： teleparallel theory Killing vectors

Morphological, Optical and DC Conduction Properties of a-GaSe Semiconductor Nanoparticle Thin Films

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Journal of Materials Science & Technology 2013年第12期29卷 1151-1155页

作者： Sushil Kumar M.A. majeed Khan Materials Science Lab. Department of Physics Chaudhary Devi Lal University Sirsa 125 055 India King Abdullah Institute for Nanotechnology King Saud University Riyadh 11451 Saudi Arabia

Amorphous gallium selenide （a-GaSe） semiconductor nanoparticle thin films were deposited onto well cleaned glass substrates by inert gas condensation （IGC） technique under a vacuum of 400 x 10-6 Pa （3 x 10-6 Torr）. The films were characterized by different structural and optical techniques, including X-ray diffraction, field emission scanning electron microscopy （FESEM）, field emission transmission electron microscopy （FETEM）, UV-visible absorption spectroscopy and I-V measurements. The particle size and size distribution were determined by TEM images which show the presence of spherical particles in the range of 5-50 nm in size. SEM images indicate that the a-GaSe film grown on glass substrate is almost smooth and dense. The optical properties of a-GaSe nanoparticle thin films were determined by optical absorption spectra. The optical bandgap of the film was estimated to be 2.19 eV and the transitions are allowed direct type. The electrical conductivity of the deposited films has been studied as a function of temperature. In the higher temperature range the dominance of thermally activated band conduction was observed; whereas in the low temperature ranqe the hoppinQ conduction in the band tails of localized states was found to be dominated.

关键词： Nanoparticles Thin film Optical bandgap Electrical conductivity

Influence of Brownian Motion, Thermophoresis and Magnetic Effects on a Fluid Containing Nanoparticles Flowing over a Stretchable Cylinder

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Fluid Dynamics & Materials Processing 2024年第3期20卷 525-536页

作者： Aaqib majeed Ahmad Zeeshan Department of Mathematics The University of FaisalabadFaisalabad38000Pakistan Department of Mathematics and Statistics FBASInternational Islamic University IslamabadIslamabad44000Pakistan

The influence of Brownian motion and thermophoresis on a fluid containing nanoparticles flowing over a stretchable cylinder is *** classical Navier-Stokes equations are considered in a porous *** addition,the Lorentz force is taken into *** controlling coupled nonlinear partial differential equations are transformed into a system of first order ordinary differential equations by means of a similarity *** resulting system of equations is solved by employing a shooting approach properly implemented in *** evolution of the boundary layer and the growing velocity is shown graphically together with the related profiles of concentration and *** magnetic field has a different influence(in terms of trends)on velocity and concentration.

关键词： Mixed convection Brownian motion heat transfer porous surface velocity slip

WELL-POSEDNESS OF A NONLINEAR MODEL OF PROLIFERATING CELL POPULATIONS WITh INhERITED CYCLE LENGTh

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Acta Mathematica Scientia 2016年第5期36卷 1225-1244页

作者： Abdul-majeed AL-IZERI Khalid LATRACh Université Blaise Pascal(Clermont Ⅱ)Laboratoire de Mathématiques CNRS UMR 6620 Campus des Cézcaux-B.P.80026 63171 Aubière Cedex France

This paper deals with a nonlinear initial boundary values problem derived from a modified version of the so called Lebowitz and Rubinow’s model [16] discussed in [8, 9]modeling a proliferating age structured cell population with inherited properties. We give existence and uniqueness results on appropriate weighted L~p-spaces with 1 ≤ p he case where the rate of cells mortality σ and the transition rate k are depending on the total density of population. General local and nonlocal reproduction rules are considered.

关键词： evolution equation local and nonlocal boundary conditions quasi-accretive operators mild solutions,strong solutions local and global solutions

ON ThE ASYMPTOTIC SPECTRUM OF A TRANSPORT OPERATOR WITh ELASTIC AND INELASTIC COLLISION OPERATORS

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Acta Mathematica Scientia 2020年第3期40卷 805-823页

作者： Abdul-majeed AL-IZERI Khalid LATRACh UniversitéClermont Auvergne CNRSLMBPF-63000 Clermont-FerrandFrance

In this article,we investigate the spectral properties of a class of neutron transport operators involving elastic and inelastic collision operators introduced by Larsen and Zweifel[1].Our analysis is manly focused on the description of the asymptotic spectrum which is very useful in the study of the properties of the solution to Cauchy problem governed by such operators(when it exists).The last section of this work is devoted to the properties of the leading eigenvalue(when it exists).So,we discuss the irreducibility of the semigroups generated by these *** close this section by discussing the strict monotonicity of the leading eigenvalue with respect to the parameters of the operator.

关键词： Compactness properties transport operator abstract boundary conditions asymptotic spectrum irreducibility leading eigenvalue