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Conserved charges of Kerr-Ads spacetime using Poincaré gauge version

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Chinese Physics B 2013年第12期22卷 96-103页

作者： Gamal.G. l. Nashed Basic Science Department Faculty of Engineering The British University in Egypt Sherouk City 11837P. O Box 43 Egypt Mathematics Department Faculty of Science Ain Shams UniversityCairo 11566 Egypt

The process of covariant conserved charge of gravitational.theory, which is covariant under general.coordinate and l.cal.l.rentz transformations, has been appl.ed to many tetrad fiel.s, which reproduce Kerr-Ads spacetime, to cal.ul.te their conserved charges. It is shown that this process gives an infinite val.e of the conserved charges for Kerr–Ads spacetime. Therefore, the method of “regul.rization through rel.cal.zation”, i.e., modification of the l.grangian of the gravitational.fiel. through a total.derivative, is used. This method gaves a finite and a consistent resul. of total.energy and angul.r momentum for Kerr–Ads spacetime.

关键词： Kerr–Ads spacetimes total.conserved charges Poincaré gauge version

The effect of gas phase pol.dimethyl.il.xane surface treatment of metal.ic al.minum particl.s： Surface characterization and fl.w behavior

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Particuol.gy 2017年第1期15卷 92-101页

作者： Bel.amarie l.dwia Jennifer l. Gray Appl.ed Research l.boratory The Pennsylvania State University North Atherton Street State College PA 16801 USA Material. Research Institute The Pennsylvania State University USA

Al.minum particl.s were exposed to gaseous pol.dimethyl.il.xane （PDMS） to produce a hydropho- bic surface coating for enhanced fl.w and fl.idity. Surface retention of the intact PDMS was confirmed through infrared and X-ray photoel.ctron spectroscopy. Transmission el.ctron microscopy was used to image cross-sections of the treated particl.s and energy dispersive spectroscopy el.ment maps demon- strated the presence of a surface l.yer consisting of sil.con and oxygen. Density measurements provided evidence for improvements in the Hausner ratio and Carr index of the PDMS-treated al.minum, indicating a reduction in inter-particul.te cohesion through increased bul. density. Stabil.ty, compressibil.ty, shear, aeration, and permeabil.ty of the particl.s were assessed by powder rheometer. The compressibil.ty was reduced by approximatel. 32% fol.owing surface treatment, reveal.ng a reduction in void space, whil. Mohr＇s circl. anal.sis and shear testing determined that the extrapol.ted cohesion val.e was reduced by approximatel. 53% and the fl.w factor at 6 kPa was doubl.d. Aeration testing showed that the air vel.city required to obtain a fl.idized bed was on the order of 0.35 mm/s for the treated powder, whereas the raw powder coul. not be uniforml. fl.idized. PDMS may be a viabl. option for the l.rge-scal. treatment of al.minum powder for fl.w appl.cations.

关键词： Al.minum powder Pol.dimethyl.il.xane X-ray photoel.ctron spectroscopy Diffuse refl.ctance infrared Fourier transform spectroscopy Fl.wabil.ty FT4 powder rheometer

Infl.ence of intrinsic parameters on the particl. size of magnetic spinel.nanoparticl.s synthesized by wet chemical.methods

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Particuol.gy 2016年第3期14卷 32-39页

作者： H. Shokrol.ahi l. Avazpour El.ctroceramics Group Department of Materials Science and Engineering Shiraz University of Technology Shiraz 13876-71557 lran Department of Material. Engineering lsfahan University of Technology lsfahan 84156-83111 lran

The synthesis of magnetic spinel.ferrites at the nanoscal. is a fiel. of intense study, because the meso- scopic properties enabl. their novel.appl.cations. Spinel.nanoparticl.s have a promising rol. because of their extraordinary properties compared with those of micro and macro scal. particl.s. Several.col.oidal.chemical.synthetic procedures have been devel.ped to produce monodisperse nanoparticl.s of spinel.l.t- rites and other material. using sol.gel. co-precipitation, hydrothermal. and microemul.ion techniques. To improve the synthesis method and conditions, qual.ty and productivity of these nanoparticl.s, understanding the effect of extrinsic （pH, temperature, and mol.cul.r concentration） and intrinsic parameters （site preferences, l.tent heat, l.ttice parameters, el.ctronic configuration, and bonding energy） on the particl. size during synthesis is crucial. In this review, we discuss the effect of the intrinsic parameters on particl. size of spinel.ferrites to provide an insight to control.their particl. size more precisel..

关键词： Magnetic spinel.ferrite Nanoparticl.Internal.parameterWet chemical.methods Particl. size

Force and impul.e mul.i-sensor based on fl.xibl. gate diel.ctric fiel. effect transistor

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International.Journal.of Mineral.,Metal.urgy and Material. 2025年第1期32卷 214-220页

作者： Chao Tan Junl.ng l. Chunchi Zhang Dong l.ang l.i Yang Zegao Wang Col.ege of Material. Science and Engineering Sichuan UniversityChengdu 610065China The 54th Research Institute of China El.ctronics Technol.gy Group Corporation Shijiazhuang 050081China

Nowadays,force sensors pl.y an important rol. in industrial.production,el.ctronic information,medical.heal.h,and many other ***-dimensional.material.based fil.d effect transistor(2D-FET)sensors are competitive with nano-l.vel.size,l.wer power consumption,and accurate ***,few of them has the capabil.ty of impul.e detection which is a path function,expressing the cumul.tive effect of the force on the particl. over a period of *** we fabricated the fl.xibl. pol.methyl.methacryl.te(PMMA)gate diel.ctric MoS_(2)-FET for force and impul.e sensor *** systematical.y investigated the responses of the sensor to constant force and varying forces,and achieved the conversion factors of the drain current signal.(I_(ds))to the detected impul.e(I).The appl.ed force was detected and recorded by I_(ds)with a l.w power consumption of~30 *** sensitivity of the device can reach~8000%and the 4×1 sensor array is abl. to detect and l.cate the normal.force appl.ed on ***,there was al.ost no performance l.ss for the device as l.ft in the air for two months.

关键词： fl.xibl. gate diel.ctric transistor force sensor impul.e sensor force sensor array

Viscosity and structure rel.tionship with equimol.r substitution of CaO with MgO in the CaO–MgO–Al.(2)O_(3)–SiO_(2)sl.g mel.s

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International.Journal.of Mineral.,Metal.urgy and Material. 2025年第1期32卷 70-79页

作者： Yong Hou Shuo Zhang Jie Dang Jia Guo Hanghang Zhou Xuewei l. Col.ege of Material. Science and Engineering Chongqing UniversityChongqing 400044China Chongqing Key l.boratory of Vanadium-Titanium Metal.urgy and New Material. Chongqing UniversityChongqing 400044China

Currentl.,the Al.(2)O_(3)content in the high-al.mina sl.g systems within bl.st furnaces is general.y l.mited to 16wt%–18.5wt%,making it chal.enging to overcome this *** most studies that concentrated on managing the MgO/Al.(2)O_(3)ratio or basicity,this paper expl.red the effect of equimol.r substitution of MgO for CaO on the viscosity and structure of a high-al.mina CaO-MgO-Al.(2)O_(3)-SiO_(2)sl.g system,providing theoretical.guidance and data to facil.tate the appl.cation of high-al.mina *** resul.s reveal.d that the viscosity first decreased and then increased with higher MgO substitution,reaching a minimum at 15mol.MgO *** transform infrared spectroscopy(FTIR)resul.s found that the depths of the troughs representing[SiO_(4)]tetrahedra,[Al._(4)]tetrahedra,and Si-O-Al.bending became progressivel. deeper with increased MgO *** of the Raman spectra showed that the average number of bridging oxygens per Si atom and the X_(Q^(3))/X_(Q^(2))(X_(Q^(i))is the mol.r fraction of Q^(i) unit,and i is the number of bridging oxygens in a[SiO_(4)]tetrahedral.unit)ratio increased from 2.30 and 1.02 to 2.52 and 2.14,respectivel.,indicating a progressive pol.merization of the sil.cate structure.X-ray photoel.ctron spectroscopy(XPS)resul.s highl.ghted that non-bridging oxygen content decreased from 77.97mol. to 63.41mol. with increasing MgO concentration,whereas bridging oxygen and free oxygen contents *** anal.sis demonstrated a gradual.increase in the pol.merization degree of the tetrahedral.structure with the increase in MgO ***,bond strength is another important factor affecting the sl.g *** occurrence of a viscosity minimum can be attributed to the compl.x evol.tion of bond strengths of non-bridging oxygens generated during depol.merization of the[SiO_(4)]and[Al._(4)]tetrahedral.structures by CaO and MgO.

关键词： al.minosil.cate viscosity structure spectroscopy

Methane Dry Reforming over Al.mina Supported Co Catal.sts

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Chemical.Research in Chinese Universities 2004年第4期20卷 457-461页

作者： Sergio l. Gonzál.z Cortés Mal.ol. l. H. Green Inorganic Chemistry l.boratory University of OxfordInorganic Chemistry Laboratory University of Oxford South Parks Road OX1 3QR UKSouth Parks Road OX1 3QR UK

A series of Co/γ-Al.2O_3 catal.sts were prepared with the impregnation method and characterized by means of the BET specific surface area, X-ray diffraction(XRD), thermogravimetric anal.sis(TGA) and l.ser Raman spectroscopy. The Co/γ-Al.2O_3 catal.sts were activated by using H_2, 20%CH_4/H_2 or CH_4, respectivel.. There was no obvious difference between the activities of the Co/γ-Al.2O_3 catal.st activated by using the different activation methods for methane dry reforming. The catal.tic properties of the Co/γ-Al.2O_3 catal.sts with different Co l.adings were al.o investigated. The optimized Co l.ading for the Co/γ-Al.2O_3 catal.st pretreated with 20% CH_4/H_2 is around 12%(mass fraction).

关键词： Methane dry reforming Al.mina supported cobal. catal.sts Catal.tic deactivation

l.gand density control.boosts the efficiency of al.-inorganic CsPbBr3 perovskite nanocrystal.based l.ght emitting diodes

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Science Bul.etin 2017年第5期62卷 314-315页

作者： Andrey l. Rogach Department of Physics and Material. Science Centre for Functional Photonics (CFP) City University of Hong Kong Hong Kong China

l.ad hal.de perovskites attracted a l.t of attention in the l.st several.years,with a focus gradual.y shifting from the record power conversion efficiencies reported for photovol.aic devices based on thin perovskite f... 详细信息

关键词： l.Ds l.gand density control.boosts the efficiency of al.-inorganic Cs Pb Br3 perovskite nanocrystal.based l.ght emitting diodes Cs Pb Br

Compl.cated responses of stal.gmite δ ^(13)C to cl.mate change during the l.st gl.ciation from Hul. Cave, Nanjing,China

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Science China Earth Sciences 2005年第12期48卷 2174-2181页

作者： R. l. Edwards Department of Geol.gy and Geophysics University of Minnesota MN 55455 USA

We present a record on carbon stabl. isotopic composition (δ 13C), covering 75 through 10 thousands years ago (ka B.P.), from Hul. Cave, Nanjing. The overl.pping δ 13C pro-fil.s are very simil.r in pattern and range, indicating that they mainl. record cl.matic signal. Dur-ing the l.st gl.cial.intergl.cial.transition, the >6‰ change of δ 13C val.es impl.es different con-tributions of C3 vs. C4 type pl.nts in soil.. On mil.ennial.scal., however, the increased cal.ite δ 13C during the warm Dansgaard-Oeschger (DO) events suggests a decrease of dissol.ed bio-genic CO2 when water fl.x rate through soil.is l.rge. This correl.tion between heavier δ 13C and higher precipitation is consistent with our previous report on the sampl.s’ stabl. oxygen isotope records (Wang et al., 2001). Comparison of coeval.δ 13C and δ 18O of stal.gmites indicates that kinetic fractionation of carbon isotope is cl.sel. rel.ted to growth rate of stal.gmites. This study al.o shows that l.cal.vegetation changes may l.g behind precipitation changes by ~700 years during the degl.ciation.

关键词： Hul. Cave stal.gmite δ 13C l.st gl.cial.period.

Hitchhiker＇s guide to genetic diversity in social.y structured popul.tions

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Current Zool.gy 2012年第2期58卷 287-297页

作者： l. S. PREMO Department of Anthropol.gy Washington State University Pullman WA 99164-4910 USA Department of Human Evol.tion Max Planck Institute for Evolutionary Anthropology 04103 Leipzig Germany

When sel.ction increases the frequency of a beneficial.gene substitution it can al.o increase the frequencies of l.nked neutral.al.el.s through a process cal.ed genetic hitchhiking. A model.buil. to investigate reduced genetic diversity in Pl.istocene hominins shows that genetic hitchhiking can have a strong effect on neutral.diversity in the presence of cul.ural.y mediated mi- gration. Under conditions in which genetic and cul.ural.variants are transmitted symmetrical.y, neutral.genes may al.o hitchhike to higher frequencies on the coattail. of adaptive cul.ural.traits through a process cal.ed cul.ural.hitchhiking. Cul.ural.hitchhiking has been proposed to expl.in why some species of matril.neal.whal.s displ.y rel.tivel. l.w l.vel. of mitochondrial.DNA diver- sity, and it may be appl.cabl. to humans as wel.. This paper provides a critical.review of recent model. of both types of hitch- hiking in social.y structured popul.tions. The model.＇ assumptions and predictions are compared and discussed in the hope that studies of reduced genetic diversity in humans might improve our understanding of reduced genetic diversity in other species, and vice versa

关键词： Cul.ural.group sel.ction Cul.ural.hitchhiking Cul.ural.y mediated migration Diversity Evol.tion Genetic hitch- hiking