Temperature effects on surface activity and application in oxidation of toluene derivatives of CTAB-SDS with KMnO4

The γ_cmc values of CTAB-SDS decrease from 63.67 mN/m at 10‡C to 36.38 mN/m at 90‡C, slightly lower than those of either CTAB or SDS. Correspondingly, the CMC of CTAB-SDS decreases almost by half. The increase of surface activity of CTAB-SDS can be attributed to the relatively weak electrostatic interaction at high temperature, which is supported by the increase of solubility of CTAB-SDS with rise in temperature. Catalytic effect on oxidation of toluene derivatives with potassium permanganate follows the order CTAB-SDS > SDS > CTAB. This is not caused by the dissociative effect of CTAB-SDS with low surface activity at low temperature, as seen from the fact that almost all oxidative products can be retrieved for different toluene derivatives and surfactants by mimicking the conditions of reaction. In the emulsifications of toluene derivatives at 90‡C, the time that turbid water layers of surfactant solutions take to become clear is the same as that of the catalytic effect on oxidation of toluene derivatives. Thus, it can be inferred that surfactants can improve the oxidation yields of toluene derivatives by increasing the contact between two reacting phases.     

A simple method improving the analyzing accuracy of circular groove guide

A simple method is introduced to improve the analysing accuracy of circular groove guide. With this method, the characteristic equation of circular groove guide is derived and its solution is given and discussed.The Project Supported by National Natural Science Foundation of P.R.China     

355nm Nd∶YAG激光在H_2中的高效一级斯托克斯转换

对脉冲Nd∶YAG激光(355 nm)在H2和H2∶He-Ar混合气体中的受激拉曼散射(SRS)进行了研究。在0.5 MPa的氢气中,同时测量到从二级反斯托克斯到三级斯托克斯的多波长输出,其总转化效率达88%;而高压下只剩下一级和二级斯托克斯输出,其中二级斯托克斯最大能量转化效率达44%(对应量子效率为63%)。由于高级斯托克斯的竞争,纯氢气中一级斯托克斯的最大能量转换效率不超过43%。通过向3 MPa氢气中掺入2 MPaAr气后,很好地抑制了二级斯托克斯的产生,从而获得了能量转换效率高达71%(对应量子效率为83%)的一级斯托克斯输出。对四波混频和级联受激拉曼散射在氢气多级斯托克斯产生中的作用以及惰性气体对它们的影响进行了讨论。     

The polar ionosphere at Zhongshan station on May 11, 1999, the day the solar wind almost disappeared

The solar wind almost disappeared on May 11, 1999: the solar wind plasma density and dynamic pressure were less than 1cm⁻³ and 0.1 nPa respectively, while the interplanetary magnetic field was northward. The polar ionospheric data observed by the multi-instruments at Zhongshan Station in Antarctica on such special event day was compared with those of the control day (May 14). It was shown that geomagnetic activity was very quiet on May 11 at Zhongshan. The magnetic pulsation, which usually occurred at about magnetic noon, did not appear. The ionosphere was steady and stratified, and the F₂ layer spread very little. The critical frequency of day-side F₂ layer, f₀F₂, was larger than that of control day, and the peak of f₀F₂ appeared 2 hours earlier. The ionospheric drift velocity was less than usual. There were intensive auroral E_s appearing at magnetic noon. All this indicates that the polar ionosphere was extremely quiet and geomagnetic field was much more dipolar on May 11. There were some signatures of auroral substorm before midnight, such as the negative deviation of the geomagnetic H component, accompanied with auroral E_s and weak Pc3 pulsation.

     

Two inequalities involving Hadamard products of positive semi-definite Hermitian matrices

We extend two inequalities involving Hadamard products of positive definite Hermitian matrices to positive semi-definite Hermitian matrices. Simultaneously, we also show the sufficient conditions for equalities to hold. Moreover, some other matrix inequalities are also obtained. Our results and methods are different from those which are obtained by S. Liu in [J. Math. Anal. Appl. 243:458–463(2000)] and B.-Y. Wang et al. in [Lin. Alg. Appl. 302–303: 163–172(1999)].     

A Novel Biomass Supported Na2CO3 System for Flue Gas Desulfurization

The breakthrough and stoichiometric SO2 adsorption efficiencies of a biomass supported Na2CO3 system (80 wt %Na2CO3/straw) have reached 48.9% and 80.6% respectively at a desulfurization temperature of 80℃.     

Structural evolution in amorphous silicon and germanium thin films.

The structural evolution in amorphous silicon and germanium thin films has been investigated by high-resolution transmission electron microscopy (HRTEM) in conjunction with autocorrelation function (ACF) analysis. The results established that the structure of as-deposited semiconductor films is of a high density of nanocrystallites embedded in the amorphous matrix. In addition, from ACF analysis, the structure of a-Ge is more ordered than that of a-Si. The density of embedded nanocrystallites in amorphous films was found to diminish with annealing temperature first, then to increase. The conclusions also corroborate well with the results of diminished medium-range order in annealed amorphous films determined previously by a variable coherence microscopy method.     

拉曼放大器中放大的自发拉曼散射与拉曼开-关增益关系的研究

研究了拉曼放大器中放大的自发拉曼散射对拉曼开－关增益的影响，并提出了一种利用自发拉曼散射谱来调整拉曼放大器位曼开－关增益平坦的方法，实验采用4个波长为14xx nm的激光二极管作为抽运源，75km的G．652光纤作为传输介质，获得了C波段附近的光放大，同时对此给出了合理的理论解释。     

SiOx纳米管的制备及其发光特性

以液态金属镓为媒介,利用热蒸发法合成大量非晶SiOx纳米管,这些纳米管管径均匀分布,平均约80 nm,长度大于10μm,且管内外径比例较小．分析发现,在实验过程中,熔入金属镓液滴中的硅元素和氧元素结合并从液滴的表面饱和析出,形成以镓为中心的非晶SiOx纳米管状结构．在室温中,利用260 nm的激发光源激发SiOx纳米管,发现在蓝光波段附近发出强而稳定的PL谱线,这可能与样品中的氧缺陷和空位有关．     

自制金割效应物理摆的研究性实验

金割效应物理摆是将数学中的优选法与物理实验中的复摆结合起来并用计算机处理数据的自制教学仪器.把金割效应物理摆作为研究性实验进行开设,更有利于培养学生的开拓精神和创新能力.