AgBr核壳乳剂的颗粒内部还原增感与表面化学增感的协同增感效应

采用对核颗粒进行还原掺杂和将其包壳的方法制备了一系列不同DMAB用量、内部有还原敏化中心(Ag₂)的AgBr核壳乳剂.这些乳剂表现出明显的增感效应.当这些乳剂分别进行表面硫、金和硫加金增感后,一方面表现出明显的协同增感效应;另一方面又随DMAB用量的提高,灰雾明显增长,特别是在金增感和硫加金增感的情况下.此外实验结果还证明,提高核乳剂的包壳速率可以在一定程度上减少核壳乳剂的灰雾.     

烟叶中β -胡萝卜素的分离纯化和测定

采用直接柱色谱的方法,用石油醚单一溶剂作为洗脱液,从霉烟或碎烟末浸膏中提取了β- 胡萝卜素纯品。通过 1H-NMR和 13 C-NMR谱图鉴定了β -胡萝卜素的结构。用高效液相色谱法(HPLC)测得β -胡萝卜素纯品的纯度为98%,测定方法准确性高、重现性好,β-胡萝卜素纯品的红外光谱图和熔点均与文献值相符。利用该方法提取β -胡萝卜素纯品,不仅收率达到80%,纯度好,而且单一溶剂作为洗脱液很容易回收再利用,因此说该方法是一种有价值的生产天然β-胡萝卜素的方法,具有良好的工业应用前景。     

Fe:LiNbO3单晶的坩埚下降法生长及其成分不均匀性研究

本文报道了用坩埚下降法生长Fe:LiNbO3晶体的新工艺.通过选择合适的原料配比、控制固液界面的温度梯度为20～40℃/cm及晶体生长速度0.8～1.5mm/h,生长出掺杂0.04mol;Fe2O3的无宏观缺陷LiNbO3单晶.XRD图谱和DTA曲线用来表征所得晶体,并且测定了从晶体下部到上部的紫外可见吸收光谱.结果表明:沿生长方向,晶胞参数a、c增大,熔点降低,晶体中的Fe2+浓度呈增加趋势,作者分析了造成成分不均匀分布的原因.     

Dark Spatial Solitary Wave Due to Cascaded x^（2） Nonlinearity

The formation of the dark spatial solitary wave in cascaded second harmonic generation processes is numerically studied based on the nonlinear-coupled equations. It is shown that the solitary wave exists when the effective three-order nonlinearity induced by cascaded second-order nonlinearity is negative.     

Stochastic Momentum Cooling——Palmer Cooling at HIRFL-CSRm

The Palmer cooling is always used for large dispersion momentum cooling in storage ring. So it will be used during the stripping injection of HIRFL-CSRm. Here the Palmer cooling is described. The optimum cooling time, optimum gain and optimum cooling bandwidth are obtained in the simulation with Palmer method. Using the Fokker-Planck equation, the particle distribution with respect to the momentum dispersion is also obtained numerically during the stochastic cooling process. This is useful for analysis of experimental data and for design of the cooling system, i.e, optimization of the system passband and gain, specification of accuracy of the signal transmission, etc.     

液晶模板法制备Au纳米线

利用非离子表面活性剂C₁₂E₄的层状液晶作为模板,以氯金酸(HAuCl₄)水溶液作为体系的水相和反应物,并利用C₁₂E₄中EO基团的还原性制备了Au的纳米线.研究表明,反应物的浓度、液晶体系的组成和反应时间都将影响产物的形貌.在适当条件下,可以得到直径约为20nm,长度达到几微米的均匀金纳米线,并探讨了纳米线形成过程中层状液晶的模板作用.     

Influence of Surface Structure of Platinum Electrodes on Electrooxidation of CO

The oxidation of CO on platinum electrodes in an acid solution was studied with the conventional electro-chemical methods and the on-line electrochemical mass spectroscopy. It was found that this reaction is strongly determined by the surface morphology of platinum. The pretreatment of platinum electrodes can change the surface properties dramatically, in consequence it can improve the electrocatalytic activity towards the electrooxidation of CO. The existence of surface active sites on the roughened platinum electrodes can be used to explain its high electrocatalysis towards the oxidation of CO.     

多重网格法在非结构网格中的应用

将多重网格法运用于非结构网格.网格是通过聚合法得到的,网格之间是相互关联的.方程的求解采用Jamson的有限体积法.给出了二维、三维情况的数值算例.     

CSR切割磁铁设计

兰州重离子加速器冷却储存环(HIRFL CSR)由一个主环(CSRm)和实验环(CSRe)构成.两个储存环的束流注入与引出都需要借助于切割磁铁的导向来完成.介绍了CSR的切割磁铁的物理设计和二维场计算. In order to satisfy the requirement of beam injection and extraction of CSR, four magnetic septums will be used in the accelerator. In the design, the shape of the lamination is optimized by 2-D magnetic field calculation. Also, in order to decrease the leakage field and obtain a satisfied field distribution, a special auxiliary coil and a shield iron plate are considered and as well as the construction of the septum leg is treated in a special way. As a result, the leakage field is almost...     

Experimental Study on 22Na(p,γ)23Mg Reaction

The reaction of ²²Na(p,γ)²³Mg has been investigated at the Radioactive Ion Beam Line in Lanzhou(RIBLL) using a radioactive beam ²³Al. The β⁺ delayed proton decay spectrum has been measured with the TOF-ΔE method and zero degree detectors. The half life of ²³Al is determined to be T_1/2=(476±45)ms by using a time scaler combined with the precision pulse generator,which is consistent with the other group's result of (470±30)ms. The known β⁺ delayed protons at E_r=0.216,0.278,0.438,0.479MeV have also observed in the experiment. The resonance strength of isospin analog state (IAS) is calculated. The resonance intensity of IAS is (11.4±6.0)meV. A new energy level of β⁺ delayed proton decay has been identified at E_x=8.916MeV,and their relative intensity also been obtained.