Effect of solvent quality on kinetics of tethered layer formation

We conducted a study of the effect of solvent quality on the kinetics of formation of a layer of polymer chains tethered to a solid substrate. In these experiments, tethering was accomplished by means of chemical bond formation between reactive sites on the surface and the end‐functional groups of the polymer chains in solution. All experimental variables were held constant except for the χ‐parameter between the polymer and solvent. Variation in the χ‐parameter was achieved by use of a series of nonpolar, organic solvents. The distinct three‐regime kinetics, typical of tethering reactions run in a good solvent and in the absence of segmental adsorption, was observed over the range of values for the χ‐parameter. As expected, an increase in the χ‐parameter (a decrease in solvent quality) did result in increased tethering density, but, contrary to expectation, no increase in tethering rate was observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5530–5537, 2004     

Attitude control by inertia wheels of a tethered interferometric SAR for topographic mapping

Various attitude control laws of a two masses tethered space system by using inertia wheels are analysed in this paper. The authors propose a zero-momentum system, consisting of the integration of three independent reaction wheels on board each platform. The control laws are derived by using a simplified attitude model and are then implemented in a three-dimensional numerical simulator, which simultaneously integrates the orbital and attitude equations. Final results show that pitch and yaw angular differences between the two platforms can be kept within values adequate for microwave remote sensing applications (10^–3 deg); in addition roll high frequency oscillations are damped.Based on a paper presented at the 11th National Congress of the Italian Association of Aeronanties and Astronautics, October 1991.     

Hohmann转移释放绳系卫星的方法研究

借助Ｈｏｈｍａｎｎ轨道转移的思想，研究一种绳系卫星释放方法并进行动力学分析．从轨道方程和Ｋｅ ｐｌｅｒ方程导出轨道转移条件．由数值计算对此方法加以说明．     

系留气球电子设备防雷试验研究与应用

处于高空中的系留气球不可避免的存在着雷电与静电危害,会对测控系统位于球囊外的电子设备造成损坏,所以有必要对此类设备进行专门的防护,保证设备能安全工作。     

充气薄膜球囊测压法的数学方程

把流动坐标原点设在球囊中心,探讨了用充气薄膜球囊测量流体压力的数学方程,提出了应优选圆球囊测压,并分析了测压误差及误差处理方法,绘出了仿真曲线与实验曲线,通过实验验证了仿真的正确性.     

系留缆绳的应用特点与发展趋势

随着系留气球平台的发展和应用,作为空中设备与地面设施的唯一连接纽带——系留缆绳,其重要性开始被人们所关注,对其安全性与可靠性的要求也越来越高。结合系留缆绳的应用需求,讨论了系留缆绳的技术特点,并对其未来的发展趋势进行了分析。     

系留缆绳的设计概述

系留缆绳是系留气球浮空器系统的关键部件,直接关系到系统运行的安全性与可靠性等。介绍了系留缆绳的分类与结构。根据其使用要求与特点,归纳了系留缆绳的设计原则,并在此基础上提出了系留缆绳的设计方法以及注意事项。     

Solid-supported biomimetic membranes with tailored lipopolymer tethers

Stable lipid membranes with controlled substrate-membrane spacing can be prepared using well-defined lipopolymers as a tether. Based on the living cationic ring-opening polymerization of 2-methyl- or 2-ethyl-2-oxazoline, lipopolymers can be synthesized bearing a lipid head group as well as a silanol reactive coupling end group. Using a “grafting onto” procedure these polymers can form dense, brush like monolayers, whose layered structures can be obtained by x-ray reflectivity measurements. By transfer of a pre-organized monolayer that is followed by vesicle fusion, stable polymer supported lipid membranes can be prepared. The substrate-membrane spacing can be controlled via the degree of polymerization, while the lateral diffusion of lipids within the membrane depends on the density of polymer tethers. Preliminary experiments implied that the membrane with long (N = 40) polymer tethers could reside trans-membrane receptors homogeneously, suggesting a large potential of this strategy.     

Development of silicon-tethered anionic reaction and its application to the synthesis of chiral A-ring moieties of Taxol™

Silicon-tethered intramolecular nucleophilic additions of a hydroxymethyl unit to ketones in β-hydroxyketones have been developed. The product obtained by this protocol was successfully converted to chiral A-ring moieties of Taxol™. Also developed was a promising silicon-tethered intramolecular α-alkylation reaction of the cyclic hydroxyketone.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.