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Substrate effects on spin relaxation in two-dimensional Dirac materials with strong spin-orbit coupling

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npj Computational Materials 2023年第1期9卷 1880-1889页

作者： Junqing xu Yuan ping Department of Chemistry and Biochemistry University of CaliforniaSanta CruzCA 95064USA

Understanding substrate effects on spin dynamics and relaxation is of key importance for spin-based information ***, the key factors that determine such effects, in particular for materials with strong spin-orbit coupling (SOC), have notbeen well understood. Here we performed first-principles real-time density-matrix dynamics simulations with SOC and the electron-phonon and electron-impurity scattering for spin lifetimes (τ_(s)) of supported/free-standing germanene, a prototypical strong SOC 2DDirac material. We show that the effects of different substrates on τ_(s) can surprisingly differ by two orders of magnitude. We find thatsubstrate effects on τs are closely related to substrate-induced modifications of the SOC-field anisotropy, which changes the spin-flip scattering matrix elements. We propose a new electronic quantity, named spin-flip angle θ↑↓, to characterize spin relaxationthrough intervalley spin-flip scattering. We find that T_(s)^(-1) is approximately proportional to the averaged value of sin^(2)( θ↑↓/2 ) , whichserves as a guiding parameter of controlling spin relaxation.

关键词： material relaxation coupling

A review of the health effects and exposure-responsible relationship of diesel particulate matter for underground mines

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International Journal of Mining Science and Technology 2017年第5期27卷 831-838页

作者： Chang ping xu Guang Department of Mining Engineering and Metallurgical Engineering Western Australian School of MinesCurtin UniversityKalgoorlie 6430Australia

The increasing use of diesel-powered equipment in confined spaces(underground mines) has the potential to over expose underground miners under the threat of diesel particulate matter(DPM). Miners in underground mines can be exposed to DPM concentrations far more than works in other industries. A great number of animal and epidemiological studies have shown that both short-term and long-term DPM exposure have adverse health effect. Based on reviews of related studies, especially some recent evidence, this paper investigated the long and short-term health effects based on animal studies and epidemiological studies. The exposure-response relationship studies were also explored and compared to the current DPM regulation or standards in some countries. This paper found that the DPM health effect studies specifically for miners are not sufficient to draw solid conclusions, and a recommendation limit of DPM concentration can be put in place for better protection of miners from DPM health risk. Current animal studies lack the use of species that have similar lung functions as human for understanding the cancer mode of action in human. And finally, the DPM health hazard will continue to be a challenging topic before the mode of action and reliable exposure-response relationship are established.

关键词： Diesel particulate matter (DPM) Underground mines Lung cancer Exposure-response relationship

Oscillation Theorems for Quasilinear Elliptic Differential Equations

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Acta Mathematica Sinica,English Series 2007年第7期23卷 1189-1198页

作者： zhi Ting xu School of Mathematical Sciences South China Normal University

By using vector Riccati transformation and averaging technique, some oscillation criteria for the quasilinear elliptic differential equation of second order,ΣNi,j=1Di[Ψ（y）Aij（x）｜Dy｜^p-2Djy]＋p（x）f（y）=0,are obtained. These theorems extend and include earlier results for the semilinear elliptic equation and PDE with p-Laplacian.

关键词： oscillation quasilinear elliptic equation second order vector Riccati transformation

Averaging Technique for the Oscillation of Second Order Damped Elliptic Equations

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Acta Mathematica Sinica,English Series 2008年第5期24卷 829-842页

作者： zhi Ting xu School of Mathematical Sciences South China Normal University Guangzhou 510631 P. R. China

By using the averaging technique, we establish some oscillation theorems for the second order damped elliptic differential equation N↑∑↓i,j=1 Di[AIY（x）Djy]＋N↑∑↓i=1 bi（x）Diy＋c（x）f（y）=0 which extend and... 详细信息

关键词： oscillation averaging technique second order elliptic differential equation damped

Color-tunable circularly polarized electroluminescence from a helical chiral multiple resonance emitter with B–N bonds

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Science China Chemistry 2023年第9期66卷 2612-2620页

作者： Li Yuan Zhen-Long Tu Jun-Wei xu Hua-Xiu Ni zhi-ping Mao Wen-Ye xu You-xuan Zheng State Key Laboratory of Coordination Chemistry Collaborative Innovation Center of Advanced MicrostructuresJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China Shenzhen Institute of Information Technology Shenzhen 518172China School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731China Guangzhou Research&Creativity Biotechnology Co.Ltd. Guangzhou 510700China

Chiral B,N-doped polycyclic aromatic hydrocarbons with circularly polarized luminescence(CPL) and small full-width at halfmaxima(FWHM) are promising multiple resonance(MR) emitters for CP organic light-emitting diodes(CP-OLEDs).This work presents a pair of chiral MR enantiomers,P/M-o[B-N]_(2)N_(2),featuring B–N bonds incorporated within a[7]-helicene *** enantiomers exhibit narrow 0-0 and 0-1 electronic transition bands,whose relative intensity can be fine-tuned by increasing doping concentrations,resulting in redshifts of the emission peak from 542 to 592 *** enantiomers show mirrorsymmetric CPL spectra with an asymmetry factor(|g_(PL)|) of 1.0×10^(-3).The hyperfluorescent CP-OLEDs with double-sensitized emitting layers display a FWHM of 33 nm,an external quantum efficiency of 25.1%,and a|g_(EL)|factor of 7.7×10^(-4).Notably,the CP-OLEDs realize color-tunable CP electroluminescence peak from 553 to 613 nm by regulating the vibrational *** work provides a novel concept for the design of helical CP-MR materials and CP-OLEDs,highlighting their potential for future applications in advanced optoelectronic devices.

关键词： chiral multiple resonance material helical chirality circularly polarized luminescence narrowband emission color-tunable circularly polarized electroluminescence

Application of fractal theory to study morphology of manganese sulfide inclusion in resulfurized free-cutting steels

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Journal of Iron and Steel Research International 2023年第1期30卷 137-149页

作者： Xiang-yu xu zhi-qi Zeng Qian-ren Tian Chen-wei Cao ping Shen Jian-xun Fu Center for Advanced Solidification Technology(CAST) State Key Laboratory of Advanced Special SteelSchool of Materials Science and EngineeringShanghai UniversityShanghai 200444China Baosight Software Co. Ltd.Information Service HeadquartersShanghai 201203China

The morphology and distribution of manganese sulfide(MnS)inclusions have a significant influence on the comprehensive performance,which is an important research field for resulfurized *** on the experiments of non-aqueous electrolyte and scanning electron microscope observation,the fractal theory was employed to study the three-dimensional morphologies of MnS *** results showed that the edge fractal dimension of MnS inclusions was between 1.59 and *** addition,similar morphology of MnS inclusions had a close fractal *** MnS edge fractal dimension is highly positively correlated with the morphological *** multifractal spectrums of MnS inclusions on two-dimensional plane of as-cast and as-rolled resulfurized free-cutting steels were *** large-size MnS inclusions belong to large probability subset,while the small-size MnS inclusions belong to small probability *** multifractal spectrum can truly and effectively reflect the difference and non-uniformity of distribution of MnS inclusions on 2D *** the premise of similar content of MnS,with the refinement of MnS inclusions,the multifractal spectrum width and the multifractal spectrum symmetry parameter were *** multifractal spectrum provides a new method for studying the second phase in materials.

关键词： MnS inclusion Morphology Fractal dimension Multifractal Resulfurized steel

Oscillation Criteria for Second Order Mixed Nonlinear Elliptic Equations

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Acta Mathematicae Applicatae Sinica 2015年第4期31卷 1049-1060页

作者： zhi-ting xu School of Mathematical Sciences South China Normal University

By using the refinement of the standard integral averaging technique, we obtain some oscillation criteria for second order mixed nonlinear elliptic equations. The results established in this paper extend and improve s... 详细信息

关键词： oscillation elliptic equations mixed nonlinear integral averaging technique

Oscillation of Second Order Semilinear Elliptic Equations with Damping

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Acta Mathematica Sinica,English Series 2010年第11期26卷 2165-2178页

作者： zhi Ting xu School of Mathematical Sciences South China Normal University Guangzhou 510631 P. R. China

We obtain some new Kamenev-type oscillation theorems for the second order semilinear elliptic differential equation with damping N ∑i,j=1Di[aij（x）Djy]＋N∑i=1bi（x）Diy＋c（x）f（y）=0 under quite general assumptions. These results are extensions of the recent results of Sun [Sun, Y. G.： New Kamenev-type oscillation criteria of second order nonlinear differential equations with damping. J. Math. Anal. Appl., 291, 341-351 （2004）] in a natural way. In particular, we do not impose any additional conditions on the damped functions bi （x） except the continuity. Several examples are given to illustrate the main results.

关键词： Oscillation damped semilinear elliptic differential equations second order

Synthesis and Cytotoxic Activity of Novel Water-soluble Prodrugs of Combretastatin A-4

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Chinese Chemical Letters 2006年第1期17卷 23-26页

作者： zhi Quart YONG Xiao ping xu Ying Chun CHEN xu BAO Ling Ling WENG Hu ZHENG Department of Medicinal Chemistry West China School of Pharmacy Sichuan University Chengdu 610041

Novel water-soluble prodrugs of combretastatin A-4 （5-8） were synthesized and evaluated for their in vitro cytotoxicity against lung carcinoma A549. Compound 5, bearing phosphoryl choline （PC） moiety, showed 90% inhibition at 32 ktg/mL concentration after 24 h. The findings showed the PC derivative would be a promising candidate for the development of new water-soluble prodrug of cytotoxic combretastatin A-4,

关键词： Combretastafin A-4 cytotoxicity phosphoryl choline water-soluble prodrug.