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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)

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Rare earth element geochemistry of Post-to Neo-archean shales from Singhbhum mobile belt, Eastern India: implications for tectonic setting and paleo-oxidation conditions

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Chinese Journal Of Geochemistry 2015年第3期34卷 401-409页

作者： akhtar R.Mir Department of Earth Sciences University of Kashmir

In the present study, trace element(including rare earth element) chemical data has been interpreted with the aim to decipher the tectonic setting and paleo-redox conditions of the Post- to Neo-archean shales from the Singhbhum Mobile Belt, eastern India. The data show moderate enrichment of compatible elements [such as Cu(avg. 59.28 ppm), Ni(avg. 59.49 ppm), V(avg.234.24 ppm) and Cr(avg. 181.23 ppm)] relative to the Post-Archean Australian Shale. Their chondrite normalized light rare earth elements are moderately fractionated [(La/Sm)Nranges from 2.21 to 5.78], whereas heavy rare earth elements show a nearly flat pattern [(Gd/Lu)Nranges from0.74 to 1.68]; this indicates that the rare earth element(REE) concentrations, rather than being severely affected by the diagenesis and weathering processes, decreased gradually from Gd to Lu. The Post-Archean Australian Shale normalized multi-element diagram shows the slight enrichment of Cr, V, Zr, Y, U and Sc, whereas Sr, Pb, Hf and Th are depleted. The notable negative anomaly of Sr indicates the least accumulation of plagioclase, which is also supported by the negative Eu-anomaly in these *** La–Th–Sc and Th–Zr–Sc tectonic setting diagrams indicate their continental arc setting. The geochemical parameters, such as U/Th, V/Cr, Ni/Co, and Cu/Zn, indicate that these shales were deposited under oxic to anoxic environmental conditions.

关键词：稀土元素地球化学特征新太古代页岩印度构造意义氧化条件移动氧化还原条件

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Morphology and ontogeny of directly differentiating shoot buds and somatic embryos in Santalum album L.

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Journal of Forestry Research 2019年第4期30卷 1179-1189页

作者： Rakhshanda akhtar Anwar Shahzad Plant Biotechnology Section Department of BotanyAligarh Muslim University

Santalum album *** a commercially important tree that yields essential oil of high medicinal *** research through organogenesis and embryogenesis has been documented but no report depicts comparative ontogeny of directly differentiating shoot buds(SB)and somatic embryos(SE).In the present study aseptic seedling derived hypocotyl segments(HC)and hypocotyl+root junction(HC+R)were used to induce SBs and SEs,*** differences between the structures were confirmed using scanning electron microscopy and histological *** medium containing 6-benzyladenine or BA(2.5μM)produced highest number of direct SB,while MS+BA(7.5μM)proved suitable for higher frequency of SE *** differentiating structures attained growth when transferred to MS medium containing a combination of BA and anaphthalene acetic acid or silver nitrate(AgNO3).A combination of indole-3-butyric acid and silver nitrate(AgNO3)in half-strength woody plant medium and lesser osmotic concentration(2%sucrose),induced rhizogenesis.

关键词： Direct somatic embryos Emblings Histology Hypocotyl Ontogenic

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Investigation of ageing effects on the electrical properties of polyaniline/silver nanocomposites

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Chinese Physics B 2011年第5期20卷 424-432页

作者： Asma Binat Afzal Muhammad Javed akhtar Physics Division PINSTECHP.O.NiloreIslamabad 45650Pakistan Department of Chemical and Material Engineering PIEASIslamabad 45650Pakistan

Polyaniline（PANI）/Ag nanocomposites, synthesized by incorporation of separately prepared silver nanoparticles in 1-methyl-2-pyrrolidinone（NMP） solution of PANI, have been aged at the accelerated temperature of 120℃ to simulate a storage period of 2 years at 25℃. The accelerated ageing of these materials is done by using the activation energy calculated from data collected using heat flow calorimetry （HFC）. The impedance spectroscopic studies of NMP plasticized aged nanocomposite films suggest a microphase separation into reduced and oxidized repeat units. There is crosslinking of the lPANI films during ageing thereby obstructing the charge transfer between PANI chains and silver nanoparticles. As a result, the resistivity is increased.

关键词： polyaniline Ag nanoparticles impedance spectroscopy ageing

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First principles study and comparison of vibrational and thermodynamic properties of XBi(X=In,Ga,B,Al)

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Chinese Physics B 2017年第9期26卷 155-159页

作者： Raheleh Pilevar Shahri Arsalan akhtar Department of Physics Payame Noor UniversityTehranIran

In the present work, vibrational and thermodynamic properties of XBi（X = B, Al, Ga, In） compounds are compared and investigated. The calculation is carried out using density functional theory（DFT） within the generalized gradient approximation（GGA） in a plane wave basis, with ultrasoft pseudopotentials. The lattice dynamical properties are calculated using density functional perturbation theory（DFPT） as implemented in Quantum ESPRESSO（QE） code. Thermodynamic properties involving phonon density of states（DOS） and specific heat at constant volume are investigated using quasiharmonic approximation（QHA） package within QE. The phonon dispersion diagrams for InBi, GaBi, BBi, and AlBi indicate that there is no imaginary phonon frequency in the entire Brillouin zone, which proves the dynamical stability of these materials. BBi has the highest thermal conductivity and InBi has the lowest thermal conductivity. AlBi has the largest and GaBi has the smallest reststrahlen band which somehow suggests the polar property of XBi materials. The phonon gaps for InBi, GaBi, BBi and AlBi are about 160 cm^-1, 150 cm^-1, 300 cm^-1, and 150 cm^-1, respectively. For all compounds,the three acoustic modes near the gamma point have a linear behavior. C_V is a function of T-3 at low temperatures while for higher temperatures it asymptotically tends to a constant as expected.

关键词： phonon dispersion reststrahlen band acoustic modes optical modes specific heat

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Self-propagating high temperature synthesis of MoSi_2 matrix composites

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Rare Metals 2006年第3期25卷 225-230页

作者： akhtar Farid S.H. Islam Materials Science and Engineering School State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

MoSi2 is presently regarded as the most important material for electrical heating and as one with huge potential for high temperature structural uses. MoSi2 and MoSi2 matrix composites were prepared by self-propagating high temperature synthesis （SHS）. Pure MoSi2 was obtained and a compound of MoSi2 and WSi2was synthesized in the form of predominant solid solution （Mo,W）Si2. By adding aluminum of 5.5 at.% to Mo-Si, the crystal structure of MoSi2 changed into a mixture of tetragonal Cllb MoSi2and hexagonal C40 Mo（Si,Al）2. The （Mo,W）Si2-Mo（Si,Al）2-W（Si,Al）2 composite materials were synthesized by adding aluminum of 5.5 at.% to Mo-W-Si. However, if the amount of the added aluminum was not larger than 2.5 at.%, it did not have any significant effect. SHS is an effective technology for synthesis of MoSi2 and MoSi2 matrix composites.

关键词： powder metallurgy MoSi2 matrix composites self-propagating high temperature synthesis molybdenumtungsten disilicide molybdenum aluminosilicide

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Detection of QTL(quantitative trait loci) associated with wood density by evaluating genetic structure and linkage disequilibrium of teak

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Journal of Forestry Research 2019年第6期30卷 2247-2258页

作者： Vivek Vaishnav Shamim akhtar Ansari Institute of Forest Productivity

To find the quantitative trait loci associated with wood density in teak(Tectona grandis L.f.), 21 co-dominant markers including 13 site specific recombinase and 8 EST-based co-dominant markers designed from lignin biosynthesis genes were applied to 174 teak plus tree clones at the National Germplasm Bank, Chandrapur,India. The germplasm bank exhibited 10.6% coefficient of variation for wood densities with 84.5 ± 31.3 genetic polymorphism(%). The highly panmictic set of genotypes(FST= 0.035 ± 0.004) harbored 96.47 ± 0.40 genetic variability(%). The average allelic frequency of the 21 codominant markers was 0.65 ± 0.11 with 12.9% pairs of loci in significant LD(p\0.05, R^2 values [ 0.1), confirming their suitability for a strong marker-trait association study. The marker CCoAMT-1 was significantly(p\0.01) associated with wood density showing stability by both GLM and MLM models and explained 4.3% of the phenotypic effect. The marker from the EST representing CCoAMT can be further developed for gene-assisted selection of elite genotypes of teak with greater wood density. Therefore, we believe that the report will help accelerate the genetic improvement and advance the breeding program of the species.

关键词： Association mapping Expressed sequence tags(EST) General linear model(GLM) Linkage disequilibrium(LD) Lignin Mixed linear model(MLM) Principal co-ordinate analysis(PCoA)

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Peristaltic flow of a heated Jeffrey fluid inside an elliptic duct:streamline analysis

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Applied Mathematics and Mechanics(English Edition) 2021年第4期42卷 583-592页

作者： S.NADEEM S.akhtar A.SALEEM Department of Mathematics Quaid-i-Azam University 45320Islamabad 44000Pakistan Department of Anatomy School of DentistryShaheed Zulfiqar Ali Bhutto Medical UniversityIslamabad 44000Pakistan

The peristaltic flow of a heated Jeffrey fluid inside a duct with an elliptic cross-section is studied.A thorough heat transfer mechanism is interpreted by analyzing the viscous effects in the energy *** governing mathematical equations give dimensionless partial differential equations after *** final simplified form of the mathematical equations is evaluated with respect to the relevant boundary conditions,and the exact solution is *** results are further illustrated by graphs,and the distinct aspects of peristaltic flow phenomena are discussed.

关键词： peristalsis elliptic duct Jeffrey fluid streamline

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Energy Conditions and Conservation Laws in LRS Bianchi Type Ⅰ Spacetimes via Noether Symmetries

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Communications in Theoretical Physics 2019年第3期71卷 298-306页

作者： Sumaira Saleem akhtar Tahir Hussain Department of Mathematics University of Peshawar

In this paper, we have completely classified the locally rotationally symmetric(LRS) Bianchi Type Ⅰ spacetimes via Noether symmetries(NS). The usual Lagrangian corresponding to LRS Bianchi Type Ⅰ metric is used to find the set of determining equations. To achieve a complete classification, these determining equations are generally integrated to find the components of NS vector field and the metric coefficients. During this procedure, several cases arise which give different Noether algebras of dimension 5,..., 9, 11, and 17. A comparison is established between the obtained NS and the Killing and homothetic vectors. Corresponding to all NS generators, the conservation laws are stated by using Noether's theorem. The metrics which we have obtained as a result of our classification are shown to be anisotropic or perfect fluids which satisfy certain energy conditions.

关键词： Bianchi type Ⅰ model Noether symmetry conservation Laws energy conditions

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Alginate encapsulation in Glycyrrhiza glabra *** phyto-chemical profiling of root extracts of in vitro converted plants using GC-MS analysis

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Asian Pacific Journal of Tropical Biomedicine 2017年第10期7卷 855-861页

作者： Rakhshanda akhtar Anwar Shahzad Plant Biotechnology Section Department of BotanyAligarh Muslim UniversityAligarh 202002Uttar PradeshIndia

Objective: To investigate the conversion potential of alginate encapsulated nodes of Glycyrrhiza glabra with phyto-chemical evaluation of root extract of field transferred ***: The excised axenic nodal segments were encapsulated in alginate matrix planted on Murashige and Skoog(1962) medium with different supplementation and formulations of PGRs. The two year old field transferred plants were evaluated for phytocompounds analysis using GC-MS ***: Varied responses were observed during the study, maximum conversion95.83% ± 2.40% was obtained in these encapsulates when planted on MS medium containing 2.5 m M Kinetin and 0.5 m M a-Naphthalene acetic acid, which eventually developed into complete plantlets in a single step. Further, GC-MS analysis showed the presence of different phyto-compounds in the methanolic root extracts of in vitro converted plants. The results obtained revealed the presence of about 47 phyto-compounds along with various potential bioactive compounds useful for industrial and pharmaceutical ***: This study investigates high frequency regeneration and conversion of Glycyrrhiza glabra in a single step in short time. Also, the in vitro raised plants are analysed for bioactive compounds after field transfer, which shows the presence of numerous compounds useful for commercial and pharmacological purposes.

关键词： Synseeds Conservation Licorice Morphogenic Chemopreventive

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