检索结果-南通市图书馆

Gain enhancement in two-stream free electron laser with a planar wiggler and an axial guide magnetic field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第9期21卷 247-250页

作者： S.Saviz z.Rezaei Farzin m.Aghamir Plasma Physics Research Center Science and Research BranchIslamic Azad University Department of Physics University of Tehran

The theory for a two-stream free electron laser （FEL） consisting of a relativistic electron beam transported alongthe axis of a planar wiggler in the presence of an axial guiding magnetic field is proposed and investigated. The electron trajectories and the small signal gain are derived. The characteristic of the linear gain and the normalized maximum gain are studied numerically. The result shows that the normalized maximum gain is considerably enhanced in comparison with that of the single stream. The effect of the difference between the energies of the two beams in this configuration of FEL is also considered, and we find that the gain is affected by the energy differences between groups 1 and 2.

关键词： wo-stream free-electron laser

Spectral features and antibacterial properties of Cu-doped znO nanoparticles prepared by sol-gel method

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第7期25卷 459-465页

作者： Alireza Samavati A F Ismail Hadi Nur z Othaman m K mustafa Centre for Sustainable Nanomaterials Ibnu Sina Institute for Scientific and Industrial ResearchUniversiti Teknologi Malaysia Advanced membrane Technology Research Centre (AmTEC) Universiti Teknologi Malaysia Faculty of Science Technology and Human Development Universiti Tun Hussein Onn Malaysia

zn（1-x）Cux O（x=0.00, 0.01, 0.03, and 0.05） nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into znO nanoparticles up to Cu concentration of 5%（x = 0.05）. However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli（Gram negative bacteria）cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped znO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.

关键词： Cu-doped znO nanoparticles photoluminescence antibacterial E.coli

Charge and spin-dependent thermal efficiency of polythiophene molecular junction in presence of dephasing

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2015年第10期24卷 576-583页

作者： z.Golsanamlou m.Bagheri Tagani H.Rahimpour Soleimani Department of Physics University of Guilan

The charge and spin-dependent thermoelectric properties of different lengths of polythiophene in a molecular junction are investigated using the B ¨uttiker probe method within Green function formalism in linear response regime. The coupling of the molecular chain to three-dimensional ferromagnetic electrodes is described by a tight-binding model for both parallel and antiparallel spin configurations. The decrease of height of transmission probability peaks and thermoelectric coefficients are observed in the presence of the B ¨uttiker probes. The reduction is more intensive in the strong dephased *** show that the spin magnetothermopower is bigger than the charge magnetothermopower due to the larger difference between the spin thermopowers with respect to the charge ones. In addition, we observed that the kind of carriers participating in the thermoelectric transport depends on the number of the thiophene rings.

关键词： polythiophene Green function thermoelectric coefficients Buttiker probes ferromagnetic elec-trodes

Shaped Co^(2+) doped TiO_(2) nanocrystals synthesized from nanotubular precursor: Structure and ferromagnetic behavior

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2017年第3期6卷 220-229页

作者： m.VRANJES J.KULJANIN JAKOVLJEVIC z.KONSTANTINOVIC A.POmAR m.STOILJKOVIC m.mITRIC T.RADETIC z.SAPONJIC Vinca Institute of Nuclear Sciences University of BelgradeP.O.Box 52211001 BelgradeSerbia Center for Solid State Physics and New materials Institute of Physics BelgradeUniversity of BelgradePregrevica 11811080 BelgradeSerbia Institut de Ciència de materials de Barcelona CSICCampus UAB08193 BellaterraSpain Faculty of Technology and metallurgy University of BelgradeKarnegijeva 411120 BelgradeSerbia

Co2+ doped TiO2 nanocrystals were synthetized by a hydrothermal treatment procedure applied to precursor dispersion of titania nanotubes and Co2+ ions. mixture of polygonal and prolate spheroid-like nanocrystals was obtained. The results of X-ray diffraction (XRD) analysis showed that resulted nanocrystals retain anatase crystal phase for both dopant concentrations (1.69 and 2.5 at%), but the crystal lattice parameters were affected. Reflection spectra revealed altered optical properties compared to bare TiO2. Room temperature ferromagnetic ordering with saturation magnetic moment in the range of 0.001–0.002 μB /Co was observed for both measured films made of Co2+ doped TiO2 nanocrystals.

关键词： hydrothermal synthesis X-ray diffraction(XRD) transmission electron microscopy(TEm) doped TiO_(2) magnetic properties

Dysregulation of RNA modification systems in clinical populations with neurocognitive disorders

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第6期19卷 1256-1261页

作者： Helen m.Knight merve DemirbugenÖz Adriana PerezGrovas-Saltijeral Division of Cells Organisms and Molecular GeneticsSchool of Life SciencesUniversity of NottinghamNottinghamUK Department of Pharmaceutical Toxicology Faculty of PharmacyAnkara UniversityAnkaraTurkey

The study of modified RNA known as epitranscriptomics has become increasingly relevant in our understanding of disease-modifying *** of N6 adenosine(m^(6)A)and C5 cytosine(m^(5)C)bases occur on mRNAs,tRNA,mt-tRNA,and rRNA species as well as non-coding *** emerging knowledge of RNA binding proteins that act as writer,reader,and eraser effector proteins,comes a new understanding of physiological processes controlled by these *** processes when spatiotemporally disrupted within cellular nanodomains in highly specialized tissues such as the brain,give rise to different forms of *** this review,we discuss accumulating evidence that changes in the m^(6)A and m^(5)C methylation systems contribute to neurocognitive *** studies first identified mutations within FmR1 to cause intellectual disability Fragile X syndromes several years before FmR1 was identified as an m^(6)A RNA reader ***,familial mutations within the m^(6)A writer gene mETTL5,m^(5)C writer genes NSUN2,NSUN3,NSUN5,and NSUN6,as well as THOC2 and THOC6 that form a protein complex with the m^(5)C reader protein ALYREF,were recognized to cause intellectual development ***,differences in expression of the m^(5)C writer and reader effector proteins,NSUN6,NSUN7,and ALYREF in brain tissue are indicated in individuals with Alzheimer's disease,individuals with a high neuropathological load or have suffered traumatic brain ***,an abundance of m^(6)A reader and anti-reader proteins are reported to change across brain regions in Lewy bodies diseases,Alzheimer's disease,and individuals with high cognitive reserve.m^(6)A-modified RNAs are also reported significantly more abundant in dementia with Lewy bodies brain tissue but significantly reduced in Parkinson's disease tissue,whilst modified RNAs are misplaced within diseased cells,particularly where synapses are *** parahippocampal brain tissue,m^(6)A modification is enri

关键词： 5-methylcytosine methylation Alzheimer's disease cognitive diseases epitranscriptomics intellectual disability Lewy body diseases N6 adenosine RNA modification

Effect of Yttrium Addition on microstructural Characteristics and Superplastic Behavior of Friction Stir Processed zK60 Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2013年第12期29卷 1116-1122页

作者： z.A.Luo G.m.Xie z.Y.ma G.L.Wang G.D.Wang State Key Laboratory of Rolling and Automation Northeastern University Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of Sciences

As-extruded zK60 and zK60-Y magnesium alloy plates were successfully processed via friction stir processing （FSP） at a tool rotation rate of 1600 r/rain and a traverse speed of 200 mm/min. FSP resulted in the formation of equiaxed recrystallized microstructures with the average grain sizes of ,-8.5 and -4.7 μm in the zK60 and zK60-Y alloys, respectively. moreover, FSP broke and dispersed the mgzn2 and W-phase （mg3zn3Y2） particles and dissolved mgzn2 phase in the FSP zK60 alloy. With the addition of rare earth element yttrium （Y） into the zK60 alloy, the ratio of the high angle grain boundaries （HAGBs） in the FSP alloys increased from 64% to 90%, and a certain amount of twins appeared in the FSP zK60-Y alloy. The maximum elongation of 1200% and optimum strain rate of 3 X 10-3 s-1 achieved at 450 °C in the FSP zK60-Y alloy were substantially higher than those of the FSP zK60 alloy. This is attributed to the fine grains with high ratio of HAGBs and the distribution of a large number of dispersed second phase particles with high thermal stability in the FSP zK60-Y alloy. Grain boundary sliding was identified as the primary deformation mechanism in the FSP zK60 and zK60-Y alloys from the superplastic data analyses and surficial morphology observations.

关键词： magnesium alloy Friction stir processing Rare earth element microstructure Superplasticity

Ultrahigh strength mg-Y-Ni alloys obtained by regulating second phases

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2020年第10期42卷 117-124页

作者： S.z.Wu X.G.Qiao m.Y.zheng School of materials Science and Engineering Harbin Institute of TechnologyHarbin150001China

mg-Y-Ni alloys with different second phases were designed by changing Y/Ni atomic ratio from 1.5 to *** microstructure and mechanical properties of as-cast and as-extruded alloys were *** as-cast mg-Y-Ni alloy with Y/Ni ratio of 1.5 is composed ofα-mg and long period stacking ordered(LPSO)*** Y/Ni ratio is equal to 1,nanoscale lamellarγ’phase and eutectic mg2Ni phase are formed in addition to LPSO *** Y/Ni ratio decreases further,the amount of eutectic mg2Ni phase increases,while the amount of LPSO phase *** extrusion,the LPSO andγ’phases are distributed along the extrusion direction,while eutectic mg2Ni phase is broken and dispersed in the as-extruded *** phase and mg2Ni phase in the alloys promote dynamic recrystallization(DRX)during extrusion,whileγ’phase inhibits ***,the mg96Y2Ni2(at.%)alloy with LPSO phase andγ’phase as the main second phases shows the strongest basal texture after *** tensile yield strength of the as-extruded mg-Y-Ni alloys increases first and then decreases with decreasing Y/Ni *** as-extruded mg96Y2Ni2(at.%)alloy with Y/Ni=1 exhibits excellent mechanical properties with tensile yield strength of 465 mPa,ultimate tensile strength of 510 mPa and elongation to failure of 7.2%,which is attributed to the synergistic effect of bulk LPSO phase and nanoscaleγ’phase.

关键词： mg-Y-Ni alloys LPSO γ’Phase mg2Ni mechanical properties

Review on Hydrogen Embrittlement of Press-hardened Steels for Automotive Applications

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 2023年第7期36卷 1123-1143页

作者： z.Wang Q.Lu z.H.Cao H.Chen m.X.Huang J.F.Wang General motors China Science Lab Shanghai201206China Department of mechanical Engineering The University of Hong KongPokfulam RoadHong Kong999077China Key Laboratory for Advanced materials of ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Press-hardened steel(PHS)with an ultimate tensile strength(UTS)of 1500 mPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achieved by hot stamping ***,the application of PHS with UTS exceeding 1500 mPa in automotive industry could be deferred due to the increased risk of hydrogen *** reduce this kind of risk,recent research efforts have been focused on various ways to optimize the microstructure of *** present review intends to summarize these efforts,to highlight present solutions to address hydrogen embrittlement,and to shed light on directions for future *** influence of microstructure on the hydrogen embrittlement of PHS has been discussed in terms of both the steel substrate and the surface *** substrate part covers the influence of martensite,carbides,inclusions,and retained austenite,while the surface part covers decarburization and oxidation,pre-coating,and trimming.

关键词： Hot stamping Press-hardened steels Coating-free Hydrogen embrittlement Fracture Al-Si coating

Exact Solutions of Fractional-Order Biological Population model

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第12期52卷 992-996页

作者： A.m.A.El-Sayed S.z.Rida A.A.m.Arafa Department of mathematics Faculty of ScienceAlexandria University Department of mathematics Faculty of ScienceSouth Valley University

In this paper, the Adomian＇s decomposition method （ADm） is presented for finding the exact solutions of a more general biological population models. A new solution is constructed in power series. The fractional der... 详细信息

关键词： biological populations model fractional Calculus decomposition method mittag-Leffier function