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Geochemistry and petrogenetic evolution of metasedimentary rocks in Bunu Area,part of Kabba-Lokoja-Igarra schist belt,sW nigeria

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Acta Geochimica 2022年第5期41卷 765-788页

作者： m.s.Kolawole e.C.Chukwu A.n.Agibe Department of Geology Federal UniversityOye-EkitiEkiti StateNigeria

Field and geochemical studies of the Bunu area,sW nigeria,were carried out on gneiss-metasedimentary rocks that consist of migmatised gneiss,quartz-mica schist,and foliated and massive *** gneissmetasedimentary rocks are interbedded with meta-igneous rock(amphibolite),all of which are intruded by granitoid and cut by basic and felsic *** data on major,trace,and rare earth elements of these rocks from the area were used to speculate on the petrogenetic and geodynamic evolution of the rocks in the ***,the metasedimentary rocks in the area have a restricted range of major oxides such as siO_(2)and Al_(2)O_(3)with low average values of FeO,mnO,CaO,and *** of average values of HsFe such as Zr,nb,and Y are moderately high in migmatitic gneiss,quartzmica schist,and low in both massive and foliated quartzite.ΣLRee average values are 124.25,132.41,and18.64 ppm respectively for migmatite gneiss,quartz-mica schist,and low in both massive and foliated *** rocks are also generally enriched in Ba,Cs,Pb,U,Cr,Rb,and Zr and depleted in Be,sr,Ti,mo,Th,and *** enrichment–depletion in major oxides and trace elements of the rocks in this area is probably a consequence of the movement of metamorphic remobilized fluids within the rocks in the area during the Pan-African or earlier events as noted in the adjacent egbe-Isanlu schist belt.A further geochemical characterisation of the rocks in the area using Log(na_(2)O/KO)vs Log(siO_(2)/Al_(2)O_(3)indicates that while the protolith of migmatised gneiss and quartzmica schist are greywackes to litharenite in compositions that of quartzites are sublitharenite to quartz *** the ternary plot of Al_(2)O_(3)-(CaO+na_(2)O)-KO for metasedimentary rocks in the area,most migmatitic gneiss and quartz-mica schist rocks plot close to average shale while quartzites mostly tend to illite compositions and almost toward the Al_(2)O_(3)-apex of the diagram attesting to depletion of

关键词： Geochemical studies metasedimentary rocks Geodynamic activities Protolith Passive continental margins

experimental study of shear properties of 3D woven composite using digital image correlation and acoustic emission

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Acta mechanica sinica 2020年第2期36卷 448-459页

作者： e.m.strungar A.s.Yankin e.m.Zubova A.V.Babushkin A.n.Dushko Center of experimental mechanics Perm National Research Polytechnic University614990 PermRussian Federation engineering Center PJsC“UeC-saturn” 152903 RybinskRussian Federation

This work is dedicated to the experimental study of the shear properties of three-dimensional reinforced composites taking into account their structural features,in Iosipescu *** strains have been determined using Vic-3D non-contact three-dimensional digital optical *** evolution of inhomogeneous strain fields on the surface of composite specimens of the structure under study has been *** variants of strain averaging in the specimen working area have been analyzed using Vic-3D ***-6 acoustic emission system has been used to assess the structural integrity of composite materials under loading.

关键词： Carbon-fiber composite 3D reinforced composite Digital image correlation Acoustic emission technique Iosipescu test

Chirping instabilities produced by a runaway electron beam at a spherical tokamak

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Plasma science and Technology 2023年第7期25卷 19-24页

作者： I m BALACHenKOV n n BAKHAReV V K GUseV m V ILIAsOVA e m KHILKeVICH P s KOReneV A e KOnKOV V B mInAeV Yu V mITRIZHKIn m I PATROV Yu V PeTROV n V sAKHAROV A e sHeVeLeV O m sKReKeL Ioffe Institute Saint-Petersburg 194021Russia Lomonosov moscow state University Moscow 119991Russia

Two different types of mHD instabilities with rapidly chirping frequency were found to arise in the Globus-m2 spherical tokamak in substantially different frequency *** first type arises at frequencies of an order of 1 mHz in ohmic plasmas at relatively low density(n_(e))m^(-3) in a wide range of toroidal magnetic fields and plasma *** type of instability was identified as compressional Alfven waves,driven by electrons,accelerated during a sawtooth *** was found that the mode frequency is sweeping in time,according to the Berk-Breizman hole-clump nonlinear chirping *** second type of wave arises in a specific single-swing regime of the central solenoid current with a very narrow plasma column,when the plasma tends to decay at extremely low density(n_(e))m^(-3) and,in fact,is an instability of the runaway electron *** exited modes cover the whole observed frequency range and are divided into several(two or three)frequency regions:approximately 0-30 mHz,60-120 mHz and sometimes 30-60 *** of the branches was also *** chirps are more rapid than for 1 mHz Alfven instability and follow an exponential *** paper,to our knowledge,is the first report of frequency chirping instabilities excited by accelerated electrons at a spherical tokamak.

关键词： Alfvén waves chirping instability spherical tokamak runaway electrons

structural, electronic, and optical properties of ZnO_(1-x)se_x alloys using first-principles calculations

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Chinese Physics B 2013年第8期22卷 581-588页

作者： muhammad Rashid Fayyaz Hussain muhammad Imran s A Ahmad n A noor m U sohaib s m Alay-e-Abbas Department of Physics simulation Laboratory the Islamia University of Bahawalpur63100 Pakistan Department of Physics University of the Punjab Quaid-e-Azam Campus54590 Lahore Pakistan Lahore Development Authority 54590 Lahore Pakistan Department of Physics GC University FaisalabadAllama Iqbal Road Faisalabad 38000 Pakistan

The structural, electronic, and optical properties of binary ZnO, Znse compounds, and their ternary ZnOl_xsex alloys are computed using the accurate full potential linearized augmented plane wave plus local orbital （FP-LAPW ＋ lo） method in the rocksalt （B 1） and zincblende （B3） crystallographic phases. The electronic band structures, fundamental energy band gaps, and densities of states for ZnO1_xsex are evaluated in the range 0 〈 x 〈 1 using Wu-Cohen （WC） generalized gradient approximation （GGA） for the exchange-correlation potential. Our calculated results of lattice parameters and bulk modulus reveal a nonlinear variation for pseudo-binary and their ternary alloys in both phases and show a considerable deviation from Vegard＇s law. It is observed that the predicted lattice parameter and bulk modulus are in good agreement with the available experimental and theoretical data. We establish that the composition dependence of band gap is semi-metallic in B1 phase, while a direct band gap is observed in B3 phase. The calculated density of states is described by taking into account the contribution of Zn 3d, O 2p, and se 4s, and the optical properties are studied in terms of dielectric functions, refractive index, reflectivity, and energy loss function for the B3 phase and are compared with the available experimental data.

关键词： density functional theory alloys structural electronic optical properties

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

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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

nanomotion of bacteria to determine metabolic profile

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nanotechnology and Precision engineering 2024年第1期7卷 1-9页

作者： s.n.Pleskova e.V.Lazarenko n.A.Bezrukov R.n.Kriukov A.V.Boryakov m.e.Dokukin s.I.surodin Research Laboratory of scanning Probe microscopy Lobachevsky State University of Nizhny NovgorodNizhny Novgorod 603950Russia Department of nanotechnology and Biotechnology Nizhny Novgorod State Technical University n.a.R.E.AlekseevNizhny Novgorod 603950Russia sarov Physics and Technology Institute National Research Nuclear University MEPhISarov 607186Russia

In addition to their visible motion such as swimming(e.g.,with the help ofﬂagella),bacteria can also exhibit nanomotion that is detectable only with highly sensitive instruments,and this study shows that it is possible to detect bacterial nanomotion using an AFm detection *** results show that the nanomotion characteristics depend on the bacterial strain,and that nanomotion can be used to sense the metabolic activity of bacteria because the oscillations are sensitive to the food preferences of the bacteria and the type of surrounding medium.

关键词： nanomotion Bacteria Cantilever Oscillation Atomic force microscopy metabolism

High Temperature Creep and superplasticity in a mg-Zn-Zr Alloy

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Journal of materials science & Technology 2012年第5期28卷 407-413页

作者： s. spigarelli m. el mehtedi m. Regev e. Gariboldi n. Lecis Dipartimento di Ingegneria Industriale e scienze matematiche Universit Politecnica delle Marche Via Brecce Bianche Ancona 60131 Italy mechanical engineering Dept. ORT Braude College Karmiel 21982 Israel Dipartimento di meccanica Politecnico di Milano via La Masa 34 20156 Milano Italy

Creep and superplasticity were investigated by testing a fine-grained extruded mg–Zn–Zr magnesium alloy under a wide range of applied stress in the temperature range between 100 and 300 ℃. Grain boundary sliding became the dominating mechanism at 200 ℃, leading to a true superplastic behaviour at 300 ℃, where superplasticity was attained even under relatively high strain rates （5×10-3 s-1 ）. By contrast, for lower temperatures, the straining process was controlled by dislocation climb. A comprehensive model, taking into account the simultaneous operation of the different mechanisms, was developed to describe the strain rate dependence on applied stress.

关键词： Creep superplasticity magnesium alloy

Approximate analytical solutions and mean energies of stationary schrodinger equation for general molecular potential

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Chinese Physics B 2021年第7期30卷 116-131页

作者： eyube e s Rawen B O Ibrahim n Department of Physics School of Physical SciencesModibbo Adama University of TechnologyP M B 2076 YolaAdamawa StateNigeria Directorate of Basic and Remedial studies Abubakar Tafawa Balewa University(ATBU)P M B 750001BauchiBauchi StateNigeria Department of Physics Faculty of ScienceP M B 1069MaiduguriBorno StateNigeria

The schrodinger equation is solved with general molecular potential via the improved quantization *** for bound state energy eigenvalues,radial eigenfunctions,mean kinetic energy,and potential energy are obtained in compact *** modeling the centrifugal term of the effective potential,a Pekeris-like approximation scheme is ***,we use the Hellmann–Feynman theorem to derive the relation for expectation *** state energy eigenvalues,wave functions and meanenergies of Woods–saxon potential,morse potential,mobius squared and Tietz–Hua oscillators are deduced from the general molecular *** addition,we use our equations to compute the bound state energy eigenvalues and expectation values for four diatomic molecules viz.H_(2),CO,HF,and O_(2).Results obtained are in perfect agreement with the data available from the literature for the potentials and *** also show that as the vibrational quantum number increases,the mean kinetic energy for the system in a Tietz–Hua potential increases slowly to a threshold value and then *** in a morse potential,the mean kinetic energy increases linearly with vibrational quantum number increasing.

关键词： general molecular potential schrodinger equation improved quantization rule

evaluating physical changes of iron oxide nanoparticles due to surface modification with oleic acid

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Chinese Physics B 2020年第10期29卷 186-194页

作者： s Rosales n Casillas A Topete O Cervantes G González J A Paz m e Cano Centro Universitario de Ciencias exactas e Ingenienas Universidad de GuadalajaraBlvd.Marcelino Garcia Burragan 1421C.P.44430GuadalajaraJaliscoMexico Centro Universitario de la Cienegu Universidad de GuadalajaraAv.Universidad 1115C.P.47820OcotlanJaliscoMexico Centro Universitario de Ciencias de In salud Universidad de Guadalajara.Sierra Mojada 950C.P.44340GuadalajaraJaliscoMexico

The physical characterization of a colloidal system of superficially modified magnetic nanoparticles (mnPs) is presented. The system consists of oleic acid-coated iron oxide nanoparticles (OAmnP) suspended in water. A structural analysis is carried out by using standard physical techniques to determine the diameter and shape of the mnPs and also the width of the coating shell. The colloidal stability and the polydispersity index of this ferrofluid are determined by using Zeta potential measurements. Additionally, the magnetic characterization is conducted by obtaining the DC magnetization loops, and the blocking temperatures are determined according to the ZFC–FC protocol. Finally, the values of power absorption density P of the ferrofluid are estimated by using a magneto-calorimetric procedure in a wide range of magnetic field amplitude H and frequency f. The experimental results exhibit spherical-like shape of OAmnP with (20 ± 4) nm in diameter. Due to the use of coating process, the parameters of the magnetization loops and the blocking temperatures are significantly modified. Hence, while the uncoated mnPs show a blocking state of the magnetization, the OAmnP are superparamagnetic above room temperature (300 K). Furthermore, the reached dependence P versus f and P versus H of the ferrofluid with coated mnPs are clearly fitted to linear and quadratic correlations, respectively, showing their accordance with the linear response theory.

关键词： nanoparticles ferrofluid magnetic hyperthermia functionalization