Photoresponsive peptide and polypeptide systems: part II. Photochromism of poly(l-ornithine) containing various azo-contents in side chains

Poly(L-ornithine)s having various azo-contents in the side chains were synthesized by the water-soluble carbodiimide procedure. The photochemical properties of the polypeptides poly[N^δ-p-(phenylazo)benzoyl-L-ornithine] (PPABLO) containing 3–77 mol% azobenzene were investigated by absorption and circular dichroism spectroscopy in hexafluoro-2-propanol (HFIP) or water, and in HFIP-water or methanol-water solvent mixtures. The photochromism of the dichroic bands of the PPABLOs containing 20–77 mol% azobenzene in the visible and ultraviolet wavelength regions was found to be mostly reversible as a function of irradiation time at different wavelengths due to the photostationary state (above 80% trans-cis photoisomerization) of the azo aromatic moieties. The PPABLO containing 3.2 mol% azobenzene in water exhibited conformational changes from random coil to helix by the addition of methanol or sodium dodecyl sulphate (SDS). The photo-induced conformational change was observed in HFIP-water-SDS solvent mixtures, while no conformational change was seen in water and HFIP-water solvent mixtures.     

电子直线加速器中计入纵向与横向耦合效应的束流包络线方程组

一、引言从束流动力学的观点出发,对于粒子束在直线加速器中的运动,有两种主要的分析方法,也即粒子轨迹跟踪法及考察束流包络运动的方法。前者是通过解单粒子运动方程,跟踪大量的单粒子运动轨迹而后进行分析;后者则是通过解束流的包络线方程,根据束流包络的变化来进     

在役加氢反应器试验板脆化和氢损伤的测定与研究

充分利用了带主焊缝的役后试板，在国内首次开展回火脆化、氢介质下断裂韧性与疲劳扩展的研究，结果表明，加氢反应器焊缝有明显的脆化表现。同时，核查了反应器开停车升温速度和降温速度规定，以及确定了裂纹允许尺寸的参考数据，为今后安全运行提供了充分的依据。     

TiB2和SiCW对Al2O3陶瓷材料高温摩擦磨损特性的影响

研究了Ａｌ２Ｏ３、Ａｌ２ｏ３／ＴｉＢ２和Ａｌ２Ｏ３／ＴｉＢ２／ＳｉＣＷ三处陶瓷材料在不同条件下的擦靡损特性。结果表明：三种陶瓷材料与硬质合金摩擦副的摩擦系数随温度温度的增加有不同的变化规律，摩擦表面的Ｘ射线衍射分析表明，摩擦系数的变化与陶瓷物膜的和结构有关，在高温下Ａｌ２Ｏ３／ＴｉＢ２陶瓷材料摩擦表面形成了具有优良的高温润性的ＴｉＯ２氧化膜，因而ＴｉＢ２的加入明显改善了Ａｌ２Ｏ３陶瓷材料 摩擦磨损     

Volatile organo-halogen trace analysis in beverages by thin-layer headspace enrichment and electron-capture gas-chromatography

Applicability of thin-layer headspace (TLHS) procedure giving an aqueous concentrate and also classical purge and trap (PT) in off-line mode to isolate and enrich volatile organohalogen compounds in common beverages was tested. Both enrichment tech-niques were used in combination with gas chromatography – electron capture detection (GC-ECD). TLHS, combined with direct aqueous injection (DAI)-GC-ECD, proved applicable in the determination of volatile organohalogen compounds in all studied beverages, while the PT in a version with no preliminary sample pre-treatment was of limited applicability. Detection limits of the TLHS-based procedure were in the order of 1 ppt. Content of volatile organohalogen compounds in a number of beverages available on the Polish market including mineral waters, beers, juices, carbonated and non-carbonated soft drinks, etc. was determined by means of TLHS-DAI-GC-ECD.     

国际乳业的热点论题：蛋白质标准化

介绍了蛋白质的标准化这一国际乳品界正热的研究和讨论题目，综述了蛋白质标准化的必要性和世界上目前采用的方法，展望了膜技术在蛋白质标准化上的应用前景。     

Finite Element Analysis of a Moving Boundary Value Problem

A finite element formulation and the solution of a set of nonlinear coupled heat and mass transfer equations for a two-phase system with a moving evaporation interface is presented. The interface condition takes into account the moisture transfer balance at the moving boundary. The finite element results were compared with existing results for a single phase system for model validation. In the two-phase system, the movement of evaporation front has an appreciable effect on the temperature and moisture distribution inside the porous medium during drying. The effect of the nondimensional heat of vapourization parameter γ on the evaporation front, temperature and moisture distribution in porous medium was studied. The higher the value of γ, the slower is the movement of the evaporation front. The temperature decreased and the moisture content increased as the nondimensional vapourization parameter γ increased. This model has potential applications in studying the heat and mass transfer characteristics in food and biomaterials.     

鄱阳湖流域水土保持与防洪治涝

鄱阳湖流域水土流失加剧了洪涝灾害。治理水土流失能增强山丘地涵养水源的能力,削洪减沙,减少库容损失,降低河床,具有明显的防洪效益。进行流域防洪规划时,应将防治水土流失与防洪治涝结合起来,因地制宣,综合治理。     

黄河中游多沙粗沙区水沙控制途径的探讨

根据黄河中游多沙粗区暴雨洪水及产流产沙特点，提出了为控制水沙危害，黄河中游治理应分两步走的战略。第一步解决近期水沙控制和耕地问题，主要措施是建设淤地坝和骨干坝。研究表明，在现状坝地，梯田条件下，为满足粮食生产需要，每平方公里需新增坝地３．１８ｈａ，且能港口控制水沙的要求。第二步是进行坡面治理，改善生态环境，以达到根治水沙的目的。     

Studies of photoconductivity in β-Apo-8′ carotenal

The photoconductive properties of a carotenoid polyene,β-Apo-8′ carotenal in polycrystalline form has been studied. The growth of the photocurrent shows an overshoot in the growth-time curve before steady state value is attained. This behaviour of photocurrent is proposed to be due to higher value of recombination coefficient than trapping coefficient. From the temperature dependence study it is observed that the steady state photocurrent, at first increases with increase of temperature, attains a maximum at a particular temperatureT _max and then decreases with temperature. TheT _max value agrees with the temperature above and below which steady state photocurrent is attained differently. Monomolecular and bimolecular recombination processes at two temperature regimes are proposed to account for the observed behaviour. The dependence of photocurrent with excitation light intensity and wavelength study provide information on the carrier generation processes. The fast decay of photocurrent have been observed at different temperatures and from this study the decay constant is calculated and it is found to be temperature independent.