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neural Regeneration Research 2025年第3期20卷 805-807页

作者： Josém.izquierdo Centro de Biología molecular Severo Ochoa(CBm) Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid(CSIC-UAM)MadridSpain

The word “senescence” comes from the Latin senescens, meaning “to begin to age”, and is characterized by a long-lasting but reversible block in proliferation, resulting from stress-induced cell cycle arrest of pre... 详细信息

关键词： Latin potential lasting

Effect　of　Ballistic-Type　Hot　Atom　Adsorption　mechanism　on　the　Phase　Diagram　of　monomer　Dimer　CO-O2　Surface　Catalytic　Reaction：　A　monte　Carlo　Simulation

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Chinese Physics Letters 2004年第6期21卷 1171-1174页

作者： m.Khalid K.m.khan A.U.Qaisrani Q.n.malik DepartmentofPhysics GomalUniversityDeraIsmailKhanPakistan nuclearPhysicsDivision PakistanInstituteofNuclearScienceandTechnology(PINSTECH)P.O.NiloreIslamabadPakistan

We investigate the effect of the ballistic mechanism on the phase diagram using a square surface. While using this mechanism whenever an O2 molecule hits a randomly vacant selected site, the molecule breaks up into atomic form and then executes a ballistic flight. The paths of the two oxygen atoms are taken exactly to be opposite to each other, i. e. anti-parallel, and the ranges of the atoms are taken to be equal, i. e.~they may fly up to 1 or 1.414 or 2 of the atomic spacing from the site of impact. Four cases have been studied on the basis of the range of hot atoms. The range of the hot oxygen atoms executing a ballistic flight might be up to the first nearest neighbourhood (1 atomic spacing from the site of impact), the second nearest neighbourhood (1.414 atomic spacing from the site of impact), the third nearest neighbourhood (2 atomic spacing from the site of impact), known as cases a, b, and c, respectively, while for case d the range of the oxygen atoms executing the ballistic flight might be up to 1 atomic spacing or 1.414 atomic spacing or 2 atomic spacing from the site of impact. The steady reactive window is observed and the continuous transition disappears. As soon as the CO partial pressure departs from zero, the production of CO2 is observed, which clearly verifies the experimental observation.

关键词： Computational physics Surfaces interfaces and thin films Condensed matter: structural mechanical & thermal Chemical physics and physical chemistry

Systematic study of Ce^(3+) on the structural and magnetic properties of Cu nanosized ferrites for potential applications

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Journal of Rare Earths 2018年第2期36卷 156-164页

作者： majid niaz Akhtar A.B.Sulong m.n.Akhtar muhammad Azhar khan Department of Physics Muhammad Nawaz Sharif University of Engineering and Technology (MNSUET) Department of mechanical and materials Engineering Faculty of Engineering and Built Environment Universiti Kebangsaan Malaysia (UKM) institute of Pure and Applied Biology Department of ZoologyBahaudin Zakariya University Department of Physics The Islamia University of Bahawalpur

Ce^（3＋） substituted Cu-spinel nanoferrites CuCe_xFe_（2-x）O_4（x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10） were synthesized via sol-gel self-combustion hybrid route. Single phase spinel ferrite of Cu nanoferrites were examined using X-ray diffraction（XRD） analysis whereas the multiphase structure was observed as Ce contents increased from x=0.06. Field emission scanning electron microscopy（FESEm）, Thermogravimetric and differential thermal analysis（TGA and DTA） and Fourier transform infrared spectroscopy（FTiR） were used to find out the morphology phase and metal stretching vibrations of Ce^（3＋） substituted nanocrystalline ferrites. The crystallite size was increased and found in the range of 25-91 nm. The agglomerations in Cu ferrite samples increase as the Ce^（3＋） concentration increases. The magnetic properties such as remanence, saturation magnetization, coercivity, Bohr magneton and magnetocrystalline anisotropy constant（K） were determined using m-H loops recorded from a vibrating sample magnetometer（VSm）. Saturation magnetization, remanence and coercivity are increased as the Ce^（3＋）contents increase in Cu nanocrystalline samples. moreover, law of approach to saturation（LoA） was used to calculate the maximum value of saturation for Ce-doped Cu nanoferrites. The soft magnetic behaviour of the Cu nanoferrite is observed as compared to the samples substituted with the increased Ce contents in Cu nanocrystalline ferrite. Bohr magneton and magnetocrystalline anisotropy are found to increase with the substitution of rare earth Ce^（3＋） contents in Cu spinel nanocrystalline ferrite. Cedoped Cu nanocrystalline ferrites with excellent properties may be suitable for potential applications in sensing, security, switching, core, multilayer chip inductor, biomedical and microwave absorption applications.

关键词： Ce-doped Cu nanocrystalline ferrites X-ray diffraction(XRD) Scanning electron microscopy(SEm) Transmission electron microscopy(TEm) Fourier transform infrared(FTiR) Vibrating sample magnetometer(VSm)

Post-annealing effect on the structural and mechanical properties of multiphase zirconia films deposited by a plasma focus device

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Chinese Physics B 2013年第12期22卷 442-450页

作者： i.A.khan R.S.Rawat R.Ahmad m.A.K.Shahid Department of Physics Government College University national institute of Education Nanyang Technological University Department of Physics GC University

nanostructured multiphase zirconia films （mZFs） are deposited on Zr substrate by the irradiation of energetic oxygen ions emanated from a plasma focus device. The oxygen operating gas pressure of 1 mbar （1 bar=105 Pa） provides the most appropriate ion energy flux to deposit crystalline ZrO2 films. X-ray diffraction （XRD） patterns reveal the formation of polycrystalline ZrO2 films. The crystallite size （CS）, crystal growth, and dislocation densities are attributed to increasing focus shots, sample axial distances, and working gas pressures. Phase and orientation transformations from t-ZrO2 to m-ZrO2 and c-ZrO2 are associated with increasing focus shots and continuous annealing. For lower （200 ℃） annealing temperature （AT）, full width at half maximum （FWHm） of diffraction peak, CS, and dislocation density （δ） for （020） plane are found to be 0.494, 16.6 nm, and 3.63×10-3 nm-2 while for higher （400 ℃） AT, these parameters for （111） plane are found to be 0.388, 20.87 nm, and 2.29×10-3 nm-2, respectively. Scanning electron microscope （SEm） results demonstrate the formation of rounded grains with uniform distribution. The estimated values of atomic ratio （O/Zr） in ZrO2 films deposited for different axial distances （6 cm, 9 cm, and 12 cm） are found to be 2.1, 2.2, and 2.3, respectively. Fourier transform infrared （FTiR） analysis reveals that the bands appearing at 441 cm-1 and 480 cm-1 belong to m-ZrO2 and t-ZrO2 phases, respectively. maximum microhardness （8.65±0.45 GPa） of ZrO2 film is ～ 6.7 times higher than the microhardness of virgin Zr.

关键词： zrconia phase transformation XRD SEm Fourier transform infrared analysis

Petrography and geochemistry of Jumara Dome sediments, Kachchh Basin: implications for provenance, tectonic setting and weathering intensity

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Chinese Journal Of Geochemistry 2014年第1期33卷 9-23页

作者： Ahmad A.H.m noufal K.n masroor Alam m Tavheed khan Department of Geology Department of civil Engineering ZH College of Engineering and Technology

in the Kachchh mainland, the Jumara Dome mixed carbonate-siliciclastic succession is represented by the Jhurio and Patcham formations and siliciclastic-dominating Chari Formation(Bathonian to Oxfordian). The Jumara Dome sediments were deposited during sea-level fluctuating, and were interrupted by storms in the shallow marine environment. The sandstones are generally medium-grained, moderately sorted, subangular to subrounded and of low sphericity. The sandstones are mineralogically mature and mainly composed of quartzarenite and subarkose. The plots of petrofacies in the Qt-F-L, Qm-F-Lt, Qp-Lv-Ls and Qm-P-K ternary diagrams suggest mainly the basement uplift source(craton interior) in rifted continental margin basin setting. The sandstones were cemented by carbonate, iron oxide and silica overgrowth. The Chemical index of Alteration values(73% sandstone and 81% shale) indicate high weathering conditions in the source area. Overall study suggests that such strong chemical weathering conditions are of unconformity with worldwide humid and warm climates during the Jurassic period. Positive correlations between Al2O3 and Fe2O3, TiO2, na2O, mgO, K2O are evident. A high correlation coefficient between Al2O3 and K2O in shale samples suggests that clay minerals control the major oxides. The analogous contents of Si, Al, Ti, LREE and TTE in the shale to PAAS with slightly depleted values of other elements ascribe a PAAS like source(granitic gneiss and minor mafics) to the present study. The petrographic and geochemical data strongly suggest that the studied sandstones/shales were deposited on a passive margin of the stable intracratonic basin.

关键词：大陆边缘盆地地球化学数据沉积物岩相学风化强度构造背景源区圆顶

Phase analysis of AlFe2B2 by synchrotron X-ray diffraction,magnetic and m?ssbauer studies

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Progress in natural Science:materials international 2017年第2期27卷 251-256页

作者： Tahir Ali m.n.khan E.Ahmed Asad Ali Physics Division Pakistan Institute of Nuclear Science and technology Department of Physics Abdul Wali khan University PinSAT Preston University

The structural and magnetic properties of essentially phase pure AlFe2B2prepared by arc melting were compared with a sample containing impurities. Analysis was carried out by means of synchrotron X-ray diffraction, magnetic measurements and m?ssbauer spectroscopy. The analysis of synchrotron X-ray diffraction data confirmed the orthorhombic structure of space group Cmmm for AlFe2B2with Al13Fe4as main impurity phase. The magnetic measurements revealed an unsaturated ferromagnetic state in AlFe2B2with a transition temperature（Tc） of 286 K. isothermal magnetization measurment at 5 K gave a saturation magnetization of 0.7 μB per Fe atom while Arrott plots establish the second order nature of ferromagnetic transition. The thermal evolution of m?ssbauer spectra confirmed the ferromagnetic nature of this material revealing an hyperfine field of 73 kOe and an isomer shift of 0.46 mm/s at 100 K. The m?ssbauer spectra of a phase pure sample was compared with the one containing impurity phases. it is suggested that the low temperature paramagnetic contribution in m?ssbauer spectra of phase pure material may have its origin in some intrinsic phenomena arising from defects or inhomogeneities in crystal structure.

关键词： AlFe2B2 Synchrotron X-ray diffraction Ferromagnetism mossbauer effect spectroscopy

Exact solutions for unsteady flow of second grade fluid generated by oscillating wall with transpiration

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Applied mathematics and mechanics(English Edition) 2014年第7期35卷 821-830页

作者： m.ABDULHAmEED i.khan D.ViERU S.SHAFiE Department of mathematical Sciences Faculty of ScienceUniversiti Teknologi Malaysia Skudai 81310 Malaysia Department of Theoretical mechanics Technical University of Iasi Iasi R-6600 Romania

A problem of unsteady flow of a second grade fluid over flat plates with the impulsive and oscillating motion, starting from rest, and with the wall transpiration is considered. The exact solutions are derived by the Laplace transform, the perturbation techniques, and an extension of the variable separation technique together with similarity arguments. These solutions are written as the sum between the permanent solutions and the transient solutions. The variations of fluid behaviors with various physical parameters are shown graphically and analyzed. The results are validated by comparing the limiting cases of the present paper with the results of the related published articles.

关键词： Stokes' problem second grade fluid wall transpiration oscillating wall

Quantum model of Bertrand Duopoly

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Chinese Physics Letters 2010年第8期27卷 11-14页

作者： Salman khan m. Ramzan m. K. khan Department of Physics Quaid-i-Azam University lslamabad 45320 Pakistan

We present a quantum model of Bertrand duopoly and study the entanglement behavior on the profit functions of the firms. Using the concept of optimal response of each firm to the price of the opponent, we find only one nash equilibirum point for the maximally entangled initial state. The presence of quantum entanglement in the initial state gives payoffs higher to the firms than the classical payoffs at the nash equilibrium. As a result, the dilemma-like situation in the classical game is resolved.

关键词： QUAnTUm theory PROFiT & loss PRiCES nASH equilibrium ECOnOPHYSiCS

non-maximal Tripartite Entanglement Degradation of Dirac and Scalar Fields in non-inertial Frames

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Communications in Theoretical Physics 2014年第3期61卷 281-288页

作者： Salman khan niaz Ali khan m.K.khan Department of Physics COMSATS Institute of Information Technology Chak Shahzad Department of Physics Quaid-i-Azam University

The π-tangle is used to study the behavior of entanglement of a nonmaximal tripartite state of both Dirac and scmar fields in accelerated frame. For Dirac fields, the degree of degradation with acceleration of both one-tangle of accelerated observer and π-tangle, for the same initial entanglement, is different by just interchanging the values of probability amplitudes. A fraction of both one-tangles and the π-tangle always survives for any choice of acceleration and the degree of initial entanglement. For scalar field, the one-tangle of accelerated observer depends on the choice of values of probability amplitudes and it vanishes in the range of infinite acceleration, whereas for 1r-tangle this is not always true. The dependence of π-tangle on probability amplitudes varies with acceleration. in the lower range of acceleration, its behavior changes by switching between the values of probability amplitudes and for larger values of acceleration this dependence on probability amplitudes vanishes. interestingly, unlike bipartite entanglement, the degradation of π-tangle against acceleration in the case of sca/ar fields is slower than for Dirac fields.

关键词： tripartite entanglement noninertial frame

Electrical features of radio-frequency atmospheric pressure helium discharge with and without dielectric electrodes

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Plasma Science and Technology 2019年第2期21卷 60-67页

作者： H ASHRAF S Z A SHAH H i A QAZi m A khan S HUSSAin m A BADAR S niAZ m SHAFiQ Department of Physics University of Sargodha Department of Physics Quaid-i-Azam University

A comparative study of radio-frequency atmospheric pressure glow discharge(rf APGD)generated in helium with and without dielectric electrodes to investigate the effect of electrodes insulation on electrical features of APGD is presented. in the α mode, both the rf APGDs remain volumetric, stable and uniform. in the γ mode, the APGD without dielectric electrodes shrinks into a constricted plasma column whereas APGD with dielectric electrodes remains stable and retains the same volume without plasma constriction even at higher densities of discharge current. A comparison of electrical features of both rf APGDs in normal and abnormal glow discharge regimes is presented. in both APGDs with and without dielectric electrodes,impedance measurements have been performed and compared with equivalent circuit *** measured impedance data is found to be in good agreement with simulated data.

关键词： radiofrequency atmospheric pressure glow discharge dielectric electrodes plasma stability control