制备大直径无气泡聚苯乙烯空心微球

 高品质聚苯乙烯（PS）空心微球是惯性约束聚变（ICF）实验用多层塑料微球靶的重要芯轴,常由乳液技术制备。针对由乳液技术制备的PS微球壳壁内容易形成气泡而且大直径微球制备困难的问题,实验研究了对壳壁内存在的气泡以及消除方法和制备大直径PS微球的制备技术。     

Measurement of Titanium and Manganese K -shell Ionization Cross Sections by Electron Impact

报道了电子引起的钛、锰原子的Ｋ壳层电离截面实验值。实验中,采用了薄靶厚衬底技术,并将衬底中反射的电子对测量值的影响进行了修正。实验结果与其他文献报道的测量结果相吻合。最后,还将实验结果与Ｃａｓｎａｔｉ等人的经验公式进行了比较。     

Preparation,characterization, and binding profile of imprinted semi-IPN cryogel composite for aluminum

Human body is greatly exposed to aluminum due to its high abundance in the environment. This nonessential metal is a threat to the patients of chronic renal disorders, as it is easily retained in their plasma and quickly accumulates in different tissues. Thus, there is great need to remove it from the aqueous environment. In this study, Al³⁺ imprinted semiinterpenetrating polymer network (semi-IPN)-based cryogel composite was prepared and applied for the purification of environmental and drinking water samples from aluminum. Poly (2-hydroxyethyl methacrylate) (pHEMA) discs were produced via cryogenic treatment and imprinted semi-IPN was introduced to the 3-(trimethoxysilyl) propyl acrylatemodified macroporous cryogel discs. The adsorption properties and selectivity of the aluminum (III) imprinted semi-IPN cryogel composite were studied in detail. The imprinted semi-IPN cryogel composite showed good selectivity towards aluminum (III) ions with the imprinting factor (IF) of 76.4 in the presence of competing copper (II), nickle (II), and iron (III) ions. The maximum adsorption capacity of 271 μmol g^-1 was obtained for aluminum (III) at pH 7.0 within 10 min using imprinted semi-IPN cryogel composite. The good selectivity and reusability of aluminum (III)-imprinted semi-IPN cryogel composite makes this material an eligible candidate for the purification of drinking water from aluminum (III) leaving important minerals remained in the water.     

Oscillatory modes of instability for flow between rotating cylinders with a transverse pressure gradient

Résumé L'analyse de l'effet du gradient transversal de la pression sur la stabilité de l'écoulement de Couette d'un fluide newtonien était basée sur la supposition que l'apparition de l'instabilité est due à la présence d'un mouvement secondaire, stationnaire et axialement symmétrique. Récemment on a demontré (Hughes et Reid) que, pour un tel écoulement, il existe des intervals de nombres d'ondes longitudinales de perturbation, pour lesquels les deux modes stationnaires inferieurs n'existent pas. Comme d'aprés le critère de Rayleigh, des couches stables et instables du fluide existent dans l'écoulement de base, il paraît raisonnable de poser la question si les modes d'oscilla tions neutres, du type étudié par Chang et Sartory pour un écoulement hydromagnetique de Couette, peuvent apparaître à ces nombres d'onde. On prouve dans ce travail qu'un tel type de mode oscillatoire des perturbations peut exister et que l'apparition de l'instabilité peut dépendre de l'apparition d'un tel mode.     

温度与应变率对钽流动应力的影响

 研究了温度在-100～400 ℃、应变率在10^-5～10³ s^-1范围内温度和应变率的变化对钽的流动应力的影响。结果表明,钽的流动应力对温度和应变率的变化相当敏感。同时还就两种本构模型对钽的温度效应与应变率效应的不同处理方法作了比较,指出Zerilli-Armstrong模型能更好地描述温度与应变率对钽流动应力的影响。     

冲击波作用下CHBr3/NaCl界面热弛豫特性研究

非透明材料冲击温度测量是通过对界面光辐射历史的观察实现的 ,因此对界面光辐射历史的研究是非透明材料冲击温度测量的基础。但由于冲击阻抗的失配导致界面上出现波的反射而引起温度的变化与界面热流动产生的温度变化交杂在一起 ,以及过程的瞬时性 ,使得对这一过程的实验研究显得非常困难。设计了一种界面波阻抗近似相同的特殊实验装置 ,用光辐射测量技术研究了在冲击压缩下CHBr3/NaCl界面的热弛豫过程。实验结果和理论分析表明CHBr3/NaCl界面的热弛豫时间在纳秒量级 ,与Grover等人的理论预估一致。     

Li_3N在生成BN反应中的作用

研究了常压高温下Li3N在B4 C与含氮化合物生成BN反应中的作用。实验结果表明 ,在 950℃高温下 ,B4 C与Si3N4 反应不生成hBN ,B4 C与NH4 Cl反应只生成少量hBN。在该两种原料中加入Li3N后 ,反应产物中hBN的生成量都明显增多。但Li3N本身没有与B4 C生成hBN的反应。由此推断 ,Li3N在上述B4 C与含氮化合物生成hBN的反应中表现出了催化作用。此外 ,在以hBN为原料 ,以Li3N为催化剂合成出cBN的温度压力区域内 ,对B4 C Si3N4 Li3N体系所做的高温高压实验没有合成出hBN或cBN。还讨论了在低压条件下原位合成cBN的探索实验中 ,应如何选择硼源和氮源的问题     

Discrete-Time Dichotomous Well-Posed Linear Systems and Generalized Schur–Nevanlinna–Pick Interpolation

We introduce a class of matrix-valued functions W called “L²- regular”. In case W is J-inner, this class coincides with the class of “strongly regular J-inner” matrix functions in the sense of Arov–Dym. We show that the class of L²-regular matrix functions is exactly the class of transfer functions for a discrete-time dichotomous (possibly infinite-dimensional) input-state-output linear system having some additional stability properties. When applied to J-inner matrix functions, we obtain a state-space realization formula for the resolvent matrix associated with a generalized Schur–Nevanlinna–Pick interpolation problem. Communicated by Daniel Alpay Submitted: August 20, 2006; Accepted: September 13, 2006     

Multilayer resonances sharpened by grating waveguide resonance

A multilayer planar structure comprising a highly reflective multilayer dielectric mirror and a corrugated waveguide is proposed for use as a narrow passband optical filter. The proposed filter has a much narrower linewidth than a usual Fabry–Perot cavity with two multilayer dielectric mirrors. It is shown that the narrowing of the linewidth is due to the strong spectral dependence of the phase of the wave reflected from the waveguide grating mirror. The shape of the pass band can be made symmetrical by a proper choice of the grating groove profile.