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f.rmation and Microstructural Characterization of.Silicon-modif.ed Aluminide Coating on Nickel-based Superalloy IN738LC

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材料热处理学报 2004年第05B期25卷 657-660页

作者： f. Shahriari f. Ashraf.zadeh A. Monshi Materials engineering department Isfahan University of Technology Isfahan IranMaterials engineering department Isfahan University of Technology Isfahan IranMaterials engineering department Isfahan University of Technology Isfahan Iran

In this investigation, aluminide coatings used to protect industrial components at high temperature and corrosive environments were modif.ed with silicon addition and the microstructural f.atures and f.rmation mechanism were evaluated. The coating on the nickel-based superalloy IN738LC was carried out by a two stage process including siliconizing at f.rst and aluminizing thereaf.er. Pack cementation siliconizing perf.rmed at 950C f.r 2, 4 and 6 hours in several powder mixtures of.Si, A12O3 and NHiCl, then aluminum was dif.used into the surf.ce of.the specimens by an industrial aluminizing process. The modif.ed coatings were characterized by means of.standard metallography, scanning electron microscopy, energy dispersive spectroscopy and X-ray dif.raction methods. The results show that Si in the coatings mainly presents in the f.rm of.secondary phases including Cr3Si, Mo5Si3 and Nii6Ti6Si7, well distributed within the NiAl matrix. The advantages of.this two stage modif.ed coating is discussed.

关键词：显微结构 IN738LC 镍超级合金扩散渗碳处理生长机制

Closed-f.rm solutions f.r f.ee vibration of.rectangular f.M thin plates resting on elastic f.undation

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Acta Mechanica Sinica 2016年第6期32卷 1088-1103页

作者： T. f. Xu Y. f. Xing Institute of.Solid Mechanics Beihang UniversityBeijing 100191 China China Academy of.Launch Vehicle Technology R&D Center Beijing 100076 China

This article presents closed-f.rm solutions f.r the f.equency analysis of.rectangular f.nctionally graded material (f.M) thin plates subjected to initially in-plane loads and with an elastic f.undation. Based on classical thin plate theory, the governing dif.erential equations are derived using Hamilton's principle. A neutral surf.ce is used to eliminate stretching-bending coupling in f.M plates on the basis of.the assumption of.constant Poisson's ratio. The resulting governing equation of.f.M thin plates has the same f.rm as homogeneous thin plates. The separation-of.variables method is adopted to obtain solutions f.r the f.ee vibration problems of.rectangular f.M thin plates with separable boundary conditions, including, f.r example, clamped plates. The obtained normal modes and f.equencies are in elegant closed f.rms, and present f.rmulations and solutions are validated by comparing present results with those in the literature and f.nite element method results obtained by the authors. A parameter study reveals the ef.ects of.the power law index n and aspect ratio a/b on f.equencies.

关键词： f.nctionally graded material f.ee vibration Rectangular plate Close f.rm solutions Neutral surf.ce

Phylogenetic reconstruction of.Chirita and allies (Gesneriaceae) with taxonomic treatments

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Journal of.Systematics and Evolution 2011年第1期49卷 50-64页

作者： James f. SMITH Department of.Biological Sciences Boise State University

Chirita D. Don, a large genus in the subf.mily Cyrtandroideae of.Gesneriaceae, has been the subject of.much debate whether it is a natural group or not. In addition, the highly heterogeneous Chirita has also been very problematic with regard to delimitation and subdivision. Here we used the nrDNA internal transcribed spacer and cpDNA trnL-f.f.r molecular phylogenetic analaysis, combined with morphological data. Our results suggest that Chirita is an artif.cial, polyphyletic genus. The most important character that def.nes Chirita, the dorso-ventrally oblique and bilamellar stigma, has evolved convergently in dif.erent clades of.diandrous Cyrtandroideae. Chirita sensu stricto only includes the species of.Chirita sect. Chirita, whereas Chirita sect. Microchirita is an independent clade located at the basal node of.the phylogenetic tree. Chirita sect. Liebigia is closely related to Didymocarpus with an entire stigma unlike other species of.Chirita. The species of.Chirita sect. Gibbosaccus, Chiritopsis, Primulina, and Wentsaiboea f.rm a monophyletic group that is sister to a strongly supported clade comprising f.ur monotypic genera Paralagarosolen, Calcareoboea, Petrocodon, and Tengia. We f.rther analyzed the morphological evolution of.Chirita and identif.ed a series of.morphological synapomorphies f.r the monophyletic groups revealed herein, and thereby provide a taxonomic treatment in this study.

关键词： Chirita D. Don morphological evolution phylogenetic reconstruction polyphyly taxonomic treatment.

Nanoscale displacement of.the image of.an atomic source of.radiation

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Chinese Optics Letters 2009年第2期7卷 149-151页

作者： Henk f. Arnoldus Department of.Physics and Astronomy Mississippi State University

Light emitted by an atomic source of.radiation appears to travel along a straight line （ray） f.om the location of.the source to the observer in the f.r f.eld. However, when the energy f.ow pattern of.the radiation is resolved with an accuracy better than an optical wavelength, it turns out that the f.eld lines are usually curved. We consider electric dipole radiation, a prime example of.which is the radiation emitted by an atom during an electronic transition, and we show that the f.eld lines of.energy f.ow are in general curves. Near the location of.the dipole, the f.eld lines exhibit a vortex structure, and in the f.r f.eld they approach a straight line. The spatial extension of.the vortex in the optical near f.eld is of.nanoscale dimension. Due to the rotation of.the f.eld lines near the source, the asymptotic limit of.a f.eld line is not exactly in the radially outward direction and as a consequence, the image in the f.r f.eld is slightly shif.ed. This sub-wavelength displacement of.the image of.the source should be amenable to experimental observation with contemporary nanoscale-precision techniques.

关键词： Atoms Electric dipole moments f.ow patterns Nanotechnology Vortex f.ow

Inf.uence of.Processing Parameters on the Strength of.Air Brazed Alumina Joints Using Aluminium Interlayer

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Journal of.Materials Science & Technology 2011年第7期27卷 641-646页

作者： A. Ibrahim f. Hasan Department of.Metallurgical and Materials Engineering University of Engineering and TechnologyLahore Pakistan

Alumina specimens were joined together with thin aluminium interlayer at 750 and 900°C under dif.erent applied pressures and holding time in air. f.exural strength of.the joints was then measured using a standard f.ur-point bend test method. Characterization of.the interf.ce was carried out to correlate the increase in f.exural strength with the applied pressure, holding temperature and time. The study showed that the strength of.joint is af.ected by all three parameters, i.e., processing temperature, holding time as well as applied pressure.

关键词： Pressure-assisted air brazing Alumina Aluminum Brazing Joining and Ceramic

Impacts of.wastewater sludge amendments in restoring nitrogen cycle in p-nitrophenol contaminated soil

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Journal of.Environmental Sciences 2011年第4期23卷 616-623页

作者： f. Olcay Topac Sagban Department of.Environmental Engineering Uludag University

The possible impacts on nitrogen-cycle in a p-nitrophenol （PNP） polluted soil and the ef.ectiveness of.wastewater sludge amendments in restoring nitrif.cation potential and urease activity were evaluated by an incubation study. The results indicated that PNP at 250 mg/kg soil inhibited urease activity, nitrif.cation potential, arginine ammonif.cation rate and heterotrophic bacteria counts to some extents. Af.er exposure to PNP, the nitrif.cation potential of.the tested soil was dramatically reduced to zero over a period of.30 days. Based on the f.ndings, nitrif.cation potential was postulated as a simple biochemical indicator f.r PNP pollution in soils. Nitrogen-cycling processes in soils responded positively to the applications of.wastewater sludges. A sludge application rate of.200 tons/ha was suf.icient f.r successf.l biostimulation of.these nitrogen processes. The microbial activities in sludge-amended, heavy PNP-polluted soils seemed to recover af.er 30–45 days, indicating the ef.ectiveness of.sludge as a usef.l soil amendment.

关键词： p-nitrophenol wastewater sludge soil pollution nitrogen-cycle biostimulation

A hybrid method to select morphometric f.atures using tensor completion and f.score rank f.r gif.ed children identif.cation

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Science China(Technological Sciences) 2021年第9期64卷 1863-1871页

作者： ZHANG Jin f.NG f.n HAN TianYi DUAN f.ng SUN Zhe CAIAf. Cesar f. SOLÉ-CASALS Jordi College of.Computer Science Nankai UniversityTianjin 300350China Department of.Artif.cial Intelligence Nankai UniversityTianjin 300350China Computational Engineering Applications Unit Head Office for Information Systems and CybersecurityRIKEN351-0198 SaitamaJapan Instituto Argentino de Radioastronomía-CCT La Plata CONICET/CIC-PBA/UNLP1894 V.ElisaArgentina Department of.Psychiatry University of CambridgeCambridge CB20SZUnited Kingdom Data and Signal Processing Group University of Vic-Central University of Catalonia08500 VicCataloniaSpain

Gif.ed children are able to learn in a more advanced way than others, probably due to neurophysiological dif.erences in the communication ef.iciency in neural pathways. Topological f.atures contribute to understanding the correlation between the brain structure and intelligence. Despite decades of.neuroscience research using MRI, methods based on brain region connectivity patterns are limited by MRI artif.cts, which theref.re leads to revisiting MRI morphometric f.atures, with the aim of.using them to directly identif. gif.ed children instead of.using brain connectivity. However, the small, high-dimensional morphometric f.ature dataset with outliers makes the task of.f.nding good classif.cation models challenging. To this end, a hybrid method is proposed that combines tensor completion and f.ature selection methods to handle outliers and then select the discriminative f.atures. The proposed method can achieve a classif.cation accuracy of.93.1%, higher than other existing algorithms, which is thus suitable f.r the small MRI datasets with outliers in supervised classif.cation scenarios.

关键词： gif.ed children identif.cation morphometric f.atures tensor completion f.ature selection

Calcium-mediated paired pulse depression in juvenile rat dorsal striatum

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Neural Regeneration Research 2012年第10期7卷 772-777页

作者： Yuf.ng Xie Michael f. Jackson John f. MacDonald Robarts Research Institute University of Western Ontario London Ontario Canada Department of.Physiology and Pharmacology University of Western Ontario London Ontario Canada Department of.Anatomy and Cell Biology University of Westem Ontario London Ontario Canada

As the major division of.the basal ganglia, neostriatum f.rms mutual connections with multiple brain areas and is critically involved in motor control and learning/memory. Long-term synaptic plasticity has been widely studied in dif.erent species recently. However, there are rare reports about the short-term synaptic plasticity in neostratium. In the present study, using f.eld excitatory postsynaptic potentials recording, we reported one f.rm of.short-term synaptic plasticity that is paired pulse depression in juvenile rat dorsal striatum slices induced by stimuli of.the white matter. The f.eld excitatory postsynaptic potentials could be abolished by α-amino-3-hydroxy-5-methylizoxazole-4-propionic acid receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione, but not by gamma-aminobutyric acid type A receptor antagonist bicuculline or dopamine D1 receptor antagonist SKf.81297. The paired pulse depression in the corticostratial pathway was dif.erent f.om paired pulse f.cilitation in the hippocampal CA1 synapse. In addition, the paired pulse depression was not af.ected by bath application of.gamma-aminobutyric acid type A receptor antagonist or dopamine D1 receptor antagonist. However, low calcium and high magnesium could attenuate the paired pulse depression. These f.ndings suggest a more complicated plasticity f.rm in the dorsal striatum of.juvenile rats that is dif.erent f.om that in the hippocampus, which is related with extracellular calcium.

关键词： paired pulses depression dorsal striatum calcium juvenile rats

Uncertainty relations f.r general phase spaces

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f.ontiers of.physics 2016年第3期11卷 51-60页

作者： Reinhard f. Werner Institut f.ir Theoretische Physik Leibniz Universitiit Hannover Germany

We describe a setup f.r obtain!ing uncertainty relations f.r arbitrary pairs of.observables related by a f.urier transf.rm. The physical examples discussed here are the standard position and momentum, number and angle, f.nite qudit systems, and strings of.qubits f.r quantum inf.rmation applications. The uncertainty relations allow f.r an arbitrary choice of.metric f.r the outcome distance, and the choice of.an exponent distinguishing, e.g., absolute and root mean square deviations. The emphasis of.this article is on developing a unif.ed treatment, in which one observable takes on values in an arbitrary locally compact Abelian group and the other in the dual group. In all cases, the phase space symmetry implies the eciuality of.measurement and preparation uncertainty bounds. There is also a straightf.rward method f.r determining the optimal bounds.

关键词： uncertainty relations phase space measurement uncertainty