Phase Equilibrium Relations in the Binary System Barium Oxide-Niobium Pentoxide

A large portion of the phase equilibrium diagram for the binary system barium oxide-niobium pentoxide has been constructed from observations of fusion characteristics and X-ray diffraction data. In the system five binary compounds were observed with BaO: Nb₂O₅ ratios of 5:2, 1:1, 6:7, 3:5, and 1:3 and a 6:1 compound was postulated. The 1:1 compound was found to melt congruently at 1,455 °C and have only one stable polymorph, although a second metastable polymorph can also be prepared. The 5:2 compound melts congruently at 1,542 °C; the 6:7, 3:5, and 1:3 phases melt incongruently at 1,330, 1,290, and 1,315 °C, respectively. The phase relations of the 6:1 compound could not be determined due to the reaction between this phase and platinum metal. No 2:1 compound was observed in this system.     

激光光散射法表征人用皮卡狂犬病疫苗分子量与人体副反应关系的观察

为了解人用皮卡狂犬病疫苗分子量与人体副反应的关系，用激光光散射法进行了实验。结果表明：当疫苗中皮卡浓度为１１．９５ｍ ｇ／ｍ ｌ时，其重均分子量Ｍ ｗ ＝ ２９．６×１０４，２０名志愿者中７人出现局部和全身过敏反应；当疫苗中皮卡浓度为１ｍ ｇ／ｍ ｌ时，其重均分子量Ｍｗ ＝ ５．６×１０４，２０名志愿者中无一人出现接种后副反应。这说明，用激光光散射法检测人用皮卡狂犬病疫苗分子量的大小与人体副反应的关系密切。     

The Photocurrent in Silver Halide Emulsion Grains as Determined by the Dember Effect

The explanation for the direction of photocurrent due to the Dember effect in silver halide emulsion grains is given for the situations where spectrally unsensitized silver halide grains were exposed to blue light and spectrally sensitized grains to green-red light.

The change of the Dember effect by varying the condition of the emulsion grains, that is, atmospheric condition, preexposure, chemical sensitization and desensitization, temperature dependence of photovoltage relaxation, the wavelength of the incident light and the ionic conductivity of silver halide grains, was observed and discussed.     

NMR分析冷冻面团在低温下的水份特性

运用NMR分析冷冻面团从-70℃升温到5℃过程中的水份特性,以及运用MRI图像显示了面团的解冻过程。面团中的水分可以分为两部分:半结合水,其横向弛豫时间(T2)约为10ms;深层结合水,其T2约为2ms。观察冷冻面团在升温过程中的质子信号幅度变化情况,可得出结论:半结合水在面团冻结时,一部分形成冰,另一部分转变成不可冻结水;深层结合水在面团冻结时不发生状态变化或迁移,提高面团中深层结合水的含量有利于冷冻面团的生产和抑制冰晶的生成。多种类型的NMR数据均可确定面团的玻璃化转变发生在约-30℃,而结晶温度为-9℃。冷冻面团中的水分可以分为三类:固态冰(29.71%);未冻结水(22.20%);深层结合水(33.81%)。     

On the Fracture Models Determined by the Continuum-strong Discontinuity Approach

The paper focuses on the Continuum Strong Discontinuity Approach (CSDA) to fracture mechanics, and the traction-separation cohesive laws induced from continuum dissipative models as their projections onto the failure interface. They are compared with the cohesive laws commonly used for the fracture simulation in quasi-brittle materials, typically concrete. Emphasis is placed in the analysis of the mechanical stress-strain states induced by the CSDA into the fracture process zone: first when the damage mechanism is initiated and, after, when the cohesive model determines the crack response. The influence of the material parameters, particularly the fracture energy and the initial continuum softening modulus, in the obtained phenomenological responses is also analyzed. Representative numerical solutions of fracture problems are finally presented.     

Specific Rate of Protein Crystallization Determined by the Guggenheim Method

The biological function of a protein is intimately related to its three-dimensional molecular structure. Although X-ray diffraction from single crystals can be employed to solve for the molecular structure, use of this method is often impeded by the slow rate of precipitation of crystals from the pH buffered, aqueous solutions of strong electrolytes which ordinarily serve as growth media. The rate of crystallization can be measured as a function of growth solution conditions by growing the crystals in a dilatometer. As the crystallization progresses, the rate of change of the system volume caused by the difference in density between the crystals and the solution is reflected in the rate of change of the height of the fluid in the capillary side arm of the dilatometer. In the case of the proteins, lysozyme, and canavalin, this height changes exponentially with time, which serves to define a first-order rate constant or specific crystallization rate, k. A dozen such experiments may be needed to determine how \(k\) depends upon pH, electrolyte concentration, and temperature. Each experiment can require 4 or 5 days to reach equilibrium. If height measurements are made equally spaced in time, however, early time data can be combined according to the Guggenheim procedure, and the value of k can be determined without the experiment having to reach equilibrium. By using this method, the time required to complete an experiment can be reduced by as much as 50 %.     

The Thermodynamic Properties of n-Pentadecane in the Liquid State, Determined by the Results of Measurements of Sound Velocity

A net algorithm is used to determine the thermodynamic properties of a liquid by the results of measurements of sound velocity. The density, isobaric expansion coefficient, isothermal compressibility, isobaric and isochoric heat capacities, enthalpy, and entropy of liquid n-pentadecane are calculated in the ranges of temperature from 303 to 433 K and pressure from 0.1 to 140 MPa. No tables of calculated thermodynamic properties of n-pentadecane are available in the literature for the given ranges of temperature and pressure.