Molecular flow and wall collision age distributions

The use of storage cells has become a standard technique for internal gas targets in conjunction with high energy storage rings. In case of spin-polarized hydrogen and deuterium gas targets the interaction of the injected atoms with the walls of the storage cell can lead to depolarization and recombination. Thus the number of wall collisions of the atoms in the target gas is important for modeling the processes of spin relaxation and recombination. It is shown in this article that the diffusion process of rarefied gases in long tubes or storage cells can be described with the help of the one-dimensional diffusion equation. Mathematical methods are presented that allow one to calculate collision age distributions (CAD) and their moments analytically. These methods provide a better understanding of the different aspects of diffusion than Monte Carlo calculations. Additionally it is shown that measurements of the atomic density or polarization of a gas sample taken from the center of the tube allow one to determine the possible range of the corresponding density weighted average values along the tube. The calculations are applied to the storage cell geometry of the HERMES internal polarized hydrogen and deuterium gas target. Received 9 July 2001 and Received in final form 18 September 2001     

UNIQUENESS PROBLEM WITH TRUNCATED MULTIPLICITIES OF MEROMORPHIC MAPPINGS FOR MOVING TARGETS

In this article,two uniqueness theorems of meromorphic mappings on moving targets with truncated multiplicities are proved.     

红外图像掠海小目标的检测算法研究

针对红外图像掠海小目标信噪比低，且易受到水天线和背景杂波干扰的特点，提出了一种红外掠海小目标的提取与检测算法。该方法的特点是：首先采用中值滤波来减小噪声，并提出了差方和算法，用以抑制背景噪声并对目标增强；再采用了图像行扫描法有效地滤除水天线；最后通过弱化背景边缘和阈值分割等综合算法得到候选小目标。仿真结果表明，该算法达到了较好的效果。     

Viscometric study of gelatin in dilute aqueous solutions

The viscosities of aqueous solutions of gelatin at different temperatures were carefully measured in a common glass‐capillary Ubbelohde viscometer at dilute to extremely dilute concentrations. The adsorption effect that occurred in the viscosity measurements was theoretically analyzed and discussed. A theory based on Langmuir isotherms could adequately describe the existing data. Some structural information was obtained by the use of an iterative fitting procedure to treat the reduced viscosity data, which disclosed that individual gelatin chains underwent a coil‐to‐helix transition as the solution cooled from 40 to 15 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1804–1812, 2006     

Brillouin light scattering from a biopolymer gel: hypersonic sound waves in gelatin

Rayleigh-Brillouin light scattering experiments were performed on gelatin gels in order to obtain the (hypersonic) sound velocity and sound attenuation as a function of gelatin concentration. The results show that in the high frequency regime there is a strong coupling in the gel between the dynamics of the network and that of the fluid. The network sound velocity varies with ^1/2. Sound attenuation increases with increasing gelatin concentration.     

黑腔靶中超热电子特性研究

近几年来,在“神光”装置上进行了1.053μm激光与平面靶及一系列柱形黑腔靶相互作用实验。用一台多道滤波—荧光X光能谱仪(FFS)测得各种靶发射的超热X射线谱,由谱推导超热电子温度T_h和超热电子总能量E_h当照射靶单束激光能量E_(tar)为400～670J、脉宽τ=650～1150ps时,发现黑腔内明显存在两群服从Maxwell分布高能电子(T_h=35～45keV;T_(hh)=150～350kev),而且E_(he)占E_(tar)的份额为10％～12％。实验还表明:腔内的E_(he)与非线性过程特征量(SRS)有较好的线性关系,因此推断出腔内超热电子产生的主要机制是受激Raman散射。在相同照射条件下,黑腔靶产生的超热电子比平面靶严重。     

New antimalarial drugs

Approximately 40% of the world population live in areas with the risk of malaria. Each year, 300-500 million people suffer from acute malaria, and 0.5-2.5 million die from the disease. Although malaria has been widely eradicated in many parts of the world, the global number of cases continues to rise. The most important reason for this alarming situation is the rapid spread of malaria parasites that are resistant to antimalarial drugs, especially chloroquine, which is by far the most frequently used. The development of new antimalarial drugs has been neglected since the 1970s owing to the end colonialism, changes in the areas of military engagement, and the restricted market potential. Only in recent years, in part supported by public funding programs, has interest in the development of antimalarial drugs been renewed. New data available from the recently sequenced genome of the malaria parasite Plasmodium falciparum and the application of methods of modern drug design promise to bring significant development in the fight against this disease.     

Hydrolysis of cellobiose by immobilized β-glucosidase entrapped in maintenance-free gel spheres

A crude preparation of Aspergillus niger β-glucosidase (27.5 cello-biase U/mg protein at 40°C, pH 5.0) was immobilized on concanavalin A-Sepharose (CAS). The cellobiase activity of the immobilized enzyme was 1334 U/mg dried CAS or 108 U/mL CAS gel. The β-glucosidase-CAS complex was entrapped within crosslinked propylene glycol alginate/bone-geletin gel spheres that possessed between 0.67 and 2.35 cellobiase U/mL spheres, depending on their size. The effect of cellobiose concentration (10–300 mM) on the activity of native, immobilized, and gel-entrapped enzyme was determined. It was shown that concentrations of cellobiose between 10 and 180 mM were not inhibitory to the entrapped enzyme, although inhibition was found to occur with the native and immobilized enzyme. Exogenous ion addition was not necessary to maintain the structural integrity of the spheres, which were stable for 4 d at 40°C.     

酶法制备明胶的新工艺研究

阐述了一种酶法制备明胶的新工艺，并对酶用量、酶解温度、酶解时间、溶胶温度、溶胶初始pH值等参数进行了优化。同时，还测定了产品的理化性质。研究表明新工艺生产周期短(7～10d)，环境污染小，产率高。     

Effects of hyaluronic acid－chitosan－gelatin complex on the apoptosis and cell cycle of L929 cells

With the development in the field of tissue engineering, the interaction between biomaterials and cells has been deeply studied. Viewing the cells seeded on the surface of materials as an organic whole, cell cycle and apoptosis are analyzed to deepen the study of cell compatibility on biomaterials, while cell proliferation and differentiation are studied at the same time. In this paper, hyaluronic acid is incorporated into the chitosan-gelatin system. Propidium iodide (PI) was used in cell cycle analysis and the double-staining of cells with annexin-V and PI was applied in cell apoptosis analysis. The results show that incorporated hyaluronic acid shortens the adaptation period of cells on the material surface, and then cells enter the normal cell cycle quickly. In addition, added hyaluronic acid inhibits cell apoptosis triggered by the membranes. Therefore, hyaluronic acid improves the cell compatibility of chitosan-gelatin system and benefits the design of biomimetic materials.