Synthesis of a novel methacrylic monomer iniferter and its application in surface photografting on crosslinked polymer substrates

(Methacryloyl ethylenedioxycarbonyl) benzyl N,N‐diethyldithiocarbamate (HEMA‐E‐In) was synthesized and used as a monomer iniferter to develop a novel, photopatternable grafting technology. This molecule functions as both a methacrylic monomer and a photoiniferter (photoinitiator–transfer agent–terminator). The structure of HEMA‐E‐In was characterized by ¹H NMR, Fourier transform infrared, and ultraviolet–visible spectroscopies. In the presence of the monomer iniferter, methyl methacrylate was polymerized by exposure to 365‐nm ultraviolet radiation, confirming the initiation capability of HEMA‐E‐In. After the copolymerization of HEMA‐E‐In into a methacrylate‐based polymer, attenuated total reflectance Fourier transform infrared spectra revealed that the photoiniferter functionality was present at the surface of this polymeric substrate. Photografting of poly(ethylene glycol) monomethacrylate monomer from the surface caused a significant change in the hydrophobicity of the surface as demonstrated by contact angle measurements. The novel monomer photoiniferter HEMA‐E‐In initiates the polymerization of bulk monomer and provides a reactive functionality that facilitates further initiation and polymer modification by the polymerization of different monomers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1885–1891, 2002     

Influence of channeling effects on ion distribution and damage profiles during high energy ion implantation in Si

Nitrogen implantation has been performed in silicon [001] crystals in carefully controlled alignment conditions. The channeling effects are clearly evident when implanting in [001] and [011] directions at energies ranging from 0.6 to 1.4 MeV. Both ion distribution and damage profiles are strongly influenced by channeling effects during ion implantation. The angular region around the [001] direction has been also investigated by implanting at small angles with respect to the axis. The same kind of study has been performed by implanting at different angles with respect to the planar (011) direction. The ion distributions (investigated by SIMS) show a strong dependence upon the alignment conditions. Moreover in high energy ion implantation, the lattice damage is located deep inside the crystal, leaving the surface layer almost unperturbed. The channeling effects on the damage production have been investigated by double crystal diffraction (DCD) in the low-dose regime and by RBS-channeling experiments (after implantation at doses greater than 1 × 10¹⁵ cm^–2) and for different ion alignment conditions.A big increase in the ion ranges and a strong reduction in the lattice damage is evident when implanting along major crystal axes. No saturatíon of the lattice damage and of the channelled component of the beam has been detected if the implantation is performed parallel to the [011] axis.     

聚碳硅烷／纳米镍粉的热裂解

聚碳硅烷／纳米镍粉的热裂解王军＊宋永才冯春祥（国防科学技术大学材料工程与应用化学系长沙４１００７３）关键词聚碳硅烷，纳米材料，镍，热解，碳化硅纤维１９９６－０９－１７收稿，１９９６－１２－１３修回国家攻关计划和“８６３”高技术资助项目聚碳硅烷（ＰＣＳ...     

Gradient extremals and valley floor bifurcations on potential energy surfaces

Gradient extremals are curves in configuration space denned by the condition that the gradient of the potential energy is an eigenvector of the Hessian matrix. Solutions of a corresponding equation go along a valley floor or along a crest of a ridge, if the norm of the gradient is a minimum, and along a cirque or a cliff or a flank of one of the two if the gradient norm is a maximum. Properties of gradient extremals are discussed for simple 2D model surfaces including the problem of valley bifurcations.     

硅钼杂多阴离子薄膜修饰电极的研究和应用——线性扫描伏安法测定水中可溶性硅酸盐

本文研究了以玻碳电极为基体的1:12硅钼杂多酸根(SiMo_(12)O_(40)~(4-)简称12-MSA)修饰电极的制备及其电化学行为,将12-MSA电极应用于线性扫描伏安法测定天然水中可溶性硅酸盐,结果满意.硅浓度在8.0×10~(-7)～1.7×10~(-3)mol/L,相对标准偏差(n=7)为1.85％,加标回收率为98.2％～103.6％,SiMo_(12)电极具有优良的选择性和稳定性。     

卡尔曼滤波分光光度法同时测定钢样中的硅、磷、砷

研究了在聚乙烯醇存在下,硅、磷、砷钼杂多酸与罗丹明6G形成离子缔合物的反应,建立了能同时测定硅、磷、砷的卡尔曼滤波分光光度法。用于钢样中微量硅、磷、砷的同时测定,操作简便快速,相对误差小于8％。     

Dynamic stereochemistry of hypervalent silicon, germanium and tin compounds containing amidomethyl C, O-chelating ligands

The results of NMR-spectroscopy studies of the structure, dynamic stereochemistry, and intermolecular interactions in solutions of organic derivatives of penta-and hexacoordinated silicon, germanium, and tin containing amidomethyl, lactamomethyl, and related bidentate ligands are surveyed. For the series of works “Dynamic stereochemistry of hypervalent compounds of silicon, germanium, and tin,” the author was awarded the Academia Europea Prize for young scientists from CIS in 1996. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1912–1934. November, 1997.     

Recoil spectrometry: Ion accelerator based elemental characterisation of surface layers

Recoil Spectrometry covers a group of techniques that are very similar to the well known Rutherford backscattering Spectrometry technique, but with the important difference that one measures the recoiling target atom rather than the projectile ion. This makes it possible to determine both the identity of the recoil and its depth of origin from its energy and velocity, using a suitable detector system. The incident ion is typically high-energy (30–100MeV)³⁵C1,⁸¹Br or¹²⁷I. Low concentrations of light elements such as C, O and N can be profiled in a heavy matrix such as Fe or GaAs. Here we present an overview of mass and energy dispersive recoil Spectrometry and illustrate its successful use in some typical applications.     

制备高比表面积碳化硅的几种影响因素

采用溶胶凝胶法，以蔗糖和正硅酸乙酯(TEOS)为原料，草酸为TEOS水解的催化剂，制备均相碳化硅前驱体，在氩气氛和高温条件下(1 350～1 600 ℃)将碳化硅先驱体进行碳热还原，制备出高比表面积的SiC。考察了水/TEOS物质的量的比、碳/硅物质的量的比及镍盐等因素对碳化硅比表面积的影响。结果表明，当n_water/n_TEOS=7.5，n_C/n_Si=4时，适宜的镍催化剂(n_Ni/n_TEOS=0.005)，凝胶形成的时间最短，镍盐的加入可使碳热还原温度降低200 ℃。     

The lion and man problem revisited

A pursuerP, whose speed is bounded by 1, wants to get closer to an evaderE, whose speed is bounded by >1.P wants to reduce his distancePE fromE below the capture radius . Both players are confined to a circular arena. This problem is equivalent to a problem discussed by Flynn, who characterized and gave numerical bounds to the least upper boundd* on the values ofPE thatE can maintain. He used direct methods and did not use Isaacs' theory.We solve our problem relying on the theory of singular surfaces in differential games. We construct and investigate barriers of the game of kind, and we replace Flynn's bounds ond* by analytical (exact) values for various speeds .The support of the TW Department of THT, Enschede, Holland, is gratefully acknowledged.