预应变对TiNi丝/Ni基复合材料的内耗行为的影响

本文对预应变TiNi形状记忆合金N／Ni基复合材料的内耗行为进行了研究。TiNi丝／Ni基复合材料是将TiNi丝作为阴极，Ni基作为阳极通过化学电镀法制成的。结果表明：随着TiNi丝预应变的增加，复合材料的相变内耗峰逐渐增宽。由于TiNi丝与Ni基之间的热膨胀系数不匹配以及回复力的产生，使复合材料在高温段的内耗有一个急剧增加过程。与TiNi合金相比，TiNi／Ni基复合材料的整体内耗整体随着温度的升高而增加的。     

Aryl acrylate based high‐internal‐phase emulsions as precursors for reactive monolithic polymer supports

Water‐in‐oil high‐internal‐phase emulsions (HIPEs), containing 4‐nitrophenyl acrylate and 2,4,6‐trichlorophenyl acrylate as reactive monomers, were prepared and polymerized, and highly porous monolithic materials resulted. The novel materials were studied by combustion analysis, Fourier transform infrared spectroscopy scanning electron microscopy, mercury porosimetry, and N₂ adsorption/desorption analysis. With both esters, cellular macroporous monolithic polymers were obtained; the use of 4‐nitrophenyl acrylate resulted in a cellular material with void diameters between 3 and 7 μm and approximately 3‐μm interconnects, whereas the use of 2,4,6‐trichlorophenyl acrylate yielded a foam with void diameters between 2 and 5 μm, most interconnects being around 1 μm. The resulting monoliths proved to be very reactive toward nucleophiles, and possibilities of functionalizing the novel polymer supports were demonstrated via reactions with amines bearing additional functional groups and via the synthesis of an acid chloride derivative. Tris(hydroxymethyl)aminomethane and tris(2‐aminoethyl)amine derivatives were obtained. The hydrolysis of 4‐nitrophenylacrylate removed the nitrophenyl group, yielding a monolithic acrylic acid polymer. Furthermore, functionalization to immobilized acid chloride was performed very efficiently, with more than 95% of the acid groups reacting. The measurement of the nitrogen content in 4‐nitrophenyl acrylate poly(HIPE)s after various times of hydrolysis showed the influence of the total pore volume of the monolithic polymers on the velocity of the reaction, which was faster with the more porous polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 296–303, 2005     

Positron diffusion in the liquid phase

We introduce effective Lagrangian with spontaneously broken density and the massive internal gauge fields based on the Sethna–Sachdev–Nelson formula, and propose an explanation for the increase of the positron diffusion length in the liquid metal phase with temperature. It is shown that the effective mass of the positron in the liquid phase decreases with temperature due to restoration of the spontaneously broken density and the massive gauge fields around the positron.     

带内螺旋翅片的T形翅片管传热特性研究

以钢质光滑管、T形翅片管及带内螺旋翅片的T形翅片管为元件，以氟利昂113—水为介质的单管池沸腾传热试验的结果表明，在试验范围内，带内螺旋翅片的T形翅片管的总传热系数是光滑管的1．9～2．6倍，是T形翅片管的1．21～1.29倍。用Wilson图解分析法得到的这种新管型的管内单相流体给热系数的方程为：hi＝0．0244λ／DiRe(0.8)Pr(0.3)，管外沸腾给热系数的方程为：h0＝5104．3q(0．04)。对试验结果和这种新管型的传热强化机理进行了讨论。     

扩展多模波导全内反射型Y分叉开关的分析

利用全内反射和波导理论，分析了多模波导反射区全内反射(Total Internal Reflection，TIR)型光开关的物理模型和降低串音和损耗的原因，给出改进Y分叉全内反射型光开关特征的近似计算方法。数值模拟表明，扩展多模波导的Y分叉全内反射开关的串音和损耗可分别下降15．5dB和0．65dB以上。     

Sol-Gel Microsphere Pelletisation Process for Fabrication of (U,Pu)O2, (U,Pu)C and (U,Pu)N Fuel Pellets for the Prototype Fast Breeder Reactor in India

A “dust-free” sol-gel microsphere pelletisation (SGMP) process has been developed for fabrication of (U,Pu)O₂, (U,Pu)C and (U,Pu)N fuel pellets containing around 15% plutonium for the forthcoming prototype fast breeder reactor (PFBR) in India. The objective was to produce homogeneous sintered pellets of ∼85% T.D. with a predominantly open-pore structure. Hydrated gel-microspheres of UO₃+PuO₂ and UO₃+PuO₂+C have been prepared from nitrate solutions of uranium and plutonium by the “ammonia internal gelation” process, using hexamethylene tetramine (HMTA) as an ammonia generator and silicone oil at 90±1°C as gelation bath. For oxide fuel pellets, the hydrated UO₃+PuO₂ gel-microspheres were calcined at around 700°C in Ar+8% H₂ atmosphere to produce “non-porous”, “free-flowing” and coarse (around 400 micron) microspheres which could be directly pelletised at 550 MPa to green pellets. The mixed oxide pellets were subjected either to low temperature (∼1100°C) oxidative sintering (LTS) in N₂+air containing ∼1500 ppm O₂ or to high temperature (1650°C) sintering, (HTS) in Ar+8% H₂. For monocarbide and mononitride pellets, hydrated gel-microspheres of UO₃+PuO₂+C were subjected to carbothermic synthesis in vacuum (∼1 Pa) and flowing nitrogen (flow rate: 1.2 m³/h) in the temperature range of 1450–1550°C respectively. The monocarbide and mononitride microspheres thus produced were relatively hard and required higher compaction pressure (∼1200 MPa) for making reen pellets which could be sintered to 85% T.D. in Ar+8% H₂ at 1700°C. The sintered oxide, monocarbide and mononitride pellets had a “blackberry” “open” pore microstructure with fine grain size. The microspheres retained their individual identity in the sintered pellets because during sintering densification took place mainly within and not between the microspheres.     

一类高阶非线性系统的几乎干扰解耦问题

对于一类高阶下三角形结构的非线性系统内稳几乎干扰解耦问题 ( ADD)的可解性 ,本文按 L2 —L2 p增益 ,使用“加幂积分器”方法 ,没有对系统中的函数作任何增长性条件限制 ,证明了文中非线性系统的ADD问题有一个连续状态反馈解 .并且可以显式解出此连续状态反馈控制器使得干扰对输出的影响可限制到任一精度且保持系统内稳 .     

Internal equatorial water waves in the f −plane

In this paper we describe an exact, and explicit, three-dimensional nonlinear solution for geophysical internal ocean waves in the Equatorial region which incorporates a transverse-Equatorial meridional current.     

Catalytic CN Bond Alkynylation of N‐Benzylic Sulfonamides with Terminal Alkynes

A new cross‐coupling reaction of N‐benzylic sulfonamides with terminal alkynes for the synthesis of internal alkynes is reported. In the presence of 5 mol% of (Tf)₂NH/Bi(OTf)₃ (1:1), a broad range of N‐benzylic sulfonamides react smoothly with arylacetylenes to afford structurally diverse internal alkynes in moderate to excellent yields. We reasoned that vinyl cations could be formed by the regioselective attack of terminal alkynes with benzyl cations generated in situ from N‐benzylic sulfonamides under acidic conditions, which then eliminated to form a carbon‐carbon triple bond.     

Inhibitory G proteins and their receptors: emerging therapeutic targets for obesity and diabetes

The worldwide prevalence of obesity is steadily increasing, nearly doubling between 1980 and 2008. Obesity is often associated with insulin resistance, a major risk factor for type 2 diabetes mellitus (T2DM): a costly chronic disease and serious public health problem. The underlying cause of T2DM is a failure of the beta cells of the pancreas to continue to produce enough insulin to counteract insulin resistance. Most current T2DM therapeutics do not prevent continued loss of insulin secretion capacity, and those that do have the potential to preserve beta cell mass and function are not effective in all patients. Therefore, developing new methods for preventing and treating obesity and T2DM is very timely and of great significance. There is now considerable literature demonstrating a link between inhibitory guanine nucleotide-binding protein (G protein) and G protein-coupled receptor (GPCR) signaling in insulin-responsive tissues and the pathogenesis of obesity and T2DM. These studies are suggesting new and emerging therapeutic targets for these conditions. In this review, we will discuss inhibitory G proteins and GPCRs that have primary actions in the beta cell and other peripheral sites as therapeutic targets for obesity and T2DM, improving satiety, insulin resistance and/or beta cell biology.