纳米羟基磷灰石的合成及分散性能研究

采用中和反应制备羟基磷灰石（HA），在反应过程中添加了六偏磷酸钠、三聚磷酸钠和“快易”作分散剂。采用X射线衍射仪（XRD）、扫描电镜（SEM）、透镜电镜（TEM）、热重和差示扫描分析（TG-DSC）等测试手段对所合成的粉末进行了表征。结果表明：分散剂添加的时间对合成粉末的粒径没有明显的影响；三种分散剂中六偏磷酸钠和三聚磷酸钠的均有较好的分散效果，粉末粒径达到纳米级。     

Three-dimensional inverse scattering of a dielectric target embedded in a lossy half-space

A modified iterative Born method is applied for three-dimensional inversion of a lossless dielectric target embedded in a lossy half-space. The forward solver employs a modified form of the extended Born method, and the half-space Green's function is computed efficiently via the complex-image technique. Example results are shown, with all scattering data based on a computational model, utilizing a rigorous forward solver distinct from that employed in the inversion. In addition, distinct gridding schemes are used in the forward and inverse solvers. Simple Tikhonov regularization is found to yield adequate results for inversion of noisy data.     

Exciton photoluminescence in doped quasi-1D structures based on silicon

The dependence of carrier density in silicon quantum wires sheathed with SiO₂ on the wire diameter and the position of impurity atoms in respect to the wire center is analyzed theoretically. It is shown that, as the diameter of wires and nanocrystals decreases, the ionization energy of a dopant increases; therefore, the free carrier density decreases, and the screening of the Coulomb attraction becomes ineffective. As a result, the photoluminescence is defined by the radiative recombination of excitons even in the case of heavily doped Si. These conclusions are supported by the data of experimental study of spectral, excitation-power, and temperature dependences of photoluminescence in porous silicon structures fabricated on lightly and heavily doped Si substrates.     

用两亲聚合物制备大颗粒苯丙乳液

分别以两亲聚合物P(C9-AA)和P(DCPD-St-α-St-AA)作乳化荆，研究了制备大颗粒(约1μm)及具有一定稳定性的苯丙乳液的方法，讨论了乳化剂，温度及引发剂用量对乳液性能的影响。结果表明，以P(C9-AA)作乳化剂时，引发剂用量为单体质量的1．2％，90℃时可以合成性能良好的苯丙乳液；以P(DCPD-St-α-St-AA)作乳化荆时，引发剂用量为单体质量的1．2％，80℃时可以合成性能良好的苯丙乳液。     

浅论太阳电池在通信工程中的应用

介绍了太阳电池应用的一般要求和太阳能供电系统的组成及运行，给出了工程设计个常用的太阳电池容量计算方法，并提出太阳能供电系统运行维护注意事项。     

数字振荡器的实现原理与仿真编程

鉴于数字信号处理中的实时应用问题，探讨了数字滤波器的实时实现原理，包括离散时间网络结构的作用和离散时间信号处理的特点，重点介绍了实时应用中实现数字滤波器的基本思想，运用MATLAB和所导出的通用数字振荡器的系统函数对一个非正弦数字振荡器进行了仿真编程，还讨论了有关实时处理的几个重要的系统性质，表达了作者对于当前学习和应用数字信号处理方法的观点。     

Preparation of trichlorosilane by plasma hydrogenation of silicon tetrachloride

We have studied silicon tetrachloride hydrogenation in an rf (40.68 MHz) plasma and have determined the trichlorosilane yield as a function of the molar energy input, H₂: SiCl₄ molar ratio, and pressure. The highest trichlorosilane yield achieved is 60%, and the minimum energy input is 0.3 kW h per mole of SiHCl₃.     

Soft X-ray emission from the plasma of a conductor exploding in a strong longitudinal magnetic field

Previous experiments with the electric explosion of conductors in a strong (50 T) longitudinal magnetic field showed the formation of a relatively low-density plasma around the central part of the explosion channel, which exhibited expansion at a velocity on the order of 10–20 km/s [1, 2]. Expansion of the plasma was accompanied by displacement of the magnetic field from the explosion channel, which was manifested by a diamagnetic signal. An analysis of the plasma energy balance is hindered by the lack of reliable data about radiative energy losses. Here, we report the first experimental results on the radiation pulse kinetics and the first estimates of the radiation energy.     

An NMR magnetometer with frequency modulation

An NMR tracking magnetometer, in which the frequency modulation is used instead of the traditional magnetic modulation, is described. Owing to the proposed digital compensation of modulation shifts, the tracking error is negligibly small and does not exceed the corresponding error for NMR magnetometers with magnetic modulation. The absence of the modulation rings decreases the sizes of the sensors to the utmost and excludes their effect on the surrounding systems. 50%-deuteron saturated solution of lithium chloride in water of 50% deuterons, which is used as a sensor substance, allows one to measure magnetic fields of 0.0625 to 15.3 T with a 10^?7 relative error at the most.     

Effect of the absence of lipoxygenase isoenzymes on the storage characteristics of rice grains

Three varieties of paddy rice with and three varieties without lipoxygenase (LOX) isoenzymes were stored at room temperature, in dark conditions for 42 months. Insect damage and viability were investigated during that time. Varieties without LOX-1,2 and their offspring were screened with a rapid method of estimating LOX isoenzymes, and subjected to an accelerated-ageing experiment. The results indicated that in varieties without LOX-1,2, after long storage, rice quality was normal, but for varieties with LOX-1,2, rice quality deteriorated. With increase of storage time, the germination rate of the seed of most varieties decreased greatly except for varieties without LOX-1,2 where there was almost no change in the germination rate. In varieties without LOX-1,2 and their offspring, after an accelerated ageing experiment the germination rate of some varieties changed slowly, but with others, the germination rate changed quickly. This indicated that a definitive factor, which influenced the life of seeds, may be the loss of LOX-1,2. During storage, there was also a significant difference in the degree of insect damage. In varieties without LOX-3 insect damage was lower, but in varieties with LOX-3 insect damage was higher. Therefore, the absence of LOX-3 may be very important in insect resistance in rice grain.