EFFECT OF THE RATIO Th/U ON TL DATING ACCURACY

ＥＦＦＥＣＴＯＦＴＨＥＲＡＴＩＯＴｈ／ＵＯＮＴＬＤＡＴＩＮＧＡＣＣＵＲＡＣＹ￥Ｐ．Ｌ．Ｌｅｕｎｇ（梁宝鎏）；ＭｉｃｈａｅｌＪ．Ｓｔｏｋｅｓ（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓａｎｄＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅ，ＣｉｔｙＰｏｌｙｔｅｃｈｎｉｃｏ...     

Mashing of rice with barley malt under non-conventional process conditions for use in food processes

Non-conventional mashing conditions are relevant in the development of a lactic acid-fermented soymilk beverage where mashed rice is the source of carbohydrates for the fermentation and sweetness of the beverage. Advantages in the process layout could be achieved by mashing at higher pH and lower malt concentrations than normally used in the brewing industry. the work reported here assessed the consequences of mashing under non-conventional conditions. Malt concentration in the cereal part was varied from 25% to 70% (w/w), pH was varied within 5.3 to 7.1, and prolongation of the holding times at 50°C and 62°C was investigated. Regression equations have been established for predicting yields of soluble protein, low molecular weight sugars and total fermentability as functions of pH and malt concentration. the results showed that the maltose yield was constant while glucose, maltotriose and total fermentable sugar yields decreased slightly with increasing pH and decreasing malt concentration. Prolonged mash holding times at 50°C and 62°C gave minor increases in protein yields only. It is concluded that it is quite acceptable to use non-conventional mashing conditions when a mashing step is integrated in other food processes.     

Phase equilibria of quasi-binary systems consisting of multicomponent polymers 1 and 2. IV: Poly(ethylene oxide)/poly(propylene oxide) systems

To confirm the reliability of the theory of phase equibria of multicomponent polymer 1/multicomponent polymer 2 systems (i.e. quasi-binary systems) and the method of computer experiment based on this theory (Brit. Polym. J., 23 (1990)285; 23 (1990)299; Polym. Int., 29 (1992)219), could point curves (CPC), two-phase volume ratios ( R ) and critical solution points (CSP) have been determined experimentally for the quasi-binary mixtures of poly(ethylene oxide) (M¯_w = 647, M¯_w/M¯_n = 1.15; M¯_w and M¯_n, the weight-average and numberaverage molecular weights, respectively) and poly(propylene oxide) (M¯_w = 2028, M¯_w/M¯_n = 1.08; and M_w = 2987, M_w/M_n = 1.13). The hydroxyl end groups of both polymers were methoxylated in advance by the Cooper & Booth method (Polymer, 18 (1977)164). The thermodynamic interaction parameter between both polymers, χ₁₂, and the concentration dependence parameters for the above quasi-binary systems were determined by the method proposed in a previous paper (Brit. Polym. J., 23 (1990)299). CPC, R and CSP values calculated on the basis of the theory are in good agreement with the values determined experimentally.     

放射性核素迁移的实验室研究——Ⅱ.用混合裂变产物溶液研究核素在地质材料上的吸附

应用裂变产物混合物做为示踪剂研究了~(137)Cs,~(141,144)Ce,~(103,106)Ru,~(103,106)Ru,~(95)Zr,~(95)Nb,~(89,90)Sr在花岗岩、凝灰岩、页岩上的吸附行为。应用批式技术测定了吸附比。核素的γ放射性是用连有SCORPIO-3000多道计算机系统的Ce(Li)探测器测量的。β放射性~(89,90)Sr是放化分离后在G-M计数器上测量的。结果表明:凝灰岩、页岩能强烈吸附Ce,Nb,Zr;吸附Cs居中;吸附Sr,Ru较差;花岗岩的吸附性能都差。     

Solubility of amaranth seed proteins in sodium sulphate and sodium chloride: the main factor in quantitative extraction for analysis

Nitrogen was extracted more efficiently from amaranth seed with 0.04 M Na₂SO₄ (5% w/v) than with either 0.09 M or 0.17 M NaCl (5% or 10% w/v), despite both solutions having the same ionic strength (μ= 1). Solubility of saline soluble proteins (albumin ± globulin) was very poor in either water or 1M NaCl, but increased in 0.4M NaCl at alkaline pH between 7 and 10. Globulins were very soluble in 0.4M NaCl at a pH 9. Albumin was the main storage protein. Saline soluble proteins formed very weak gels.     

Preparation and properties of silicone‐containing poly(methyl methacrylate) gels

Poly(methyl methacrylate) (PMMA) gels with varying amounts of silicone and solvent and constant amounts of crosslinker were prepared by solution free radical crosslinking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) comonomer systems. They were then studied in benzene at a total monomer concentration of 3.5 mol L^?1 and 70 °C. The conversion of monomer, volume swelling ratio, weight fraction and gel point were measured as a function of the reaction time, silicone concentration and benzene content up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in benzene, gel fraction and Fourier‐transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by SEM. Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the VTES or TEOS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, W_g, and its equilibrium volume swelling ratio in benzene, q_v, exhibited the same behaviour as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TEOS is not an ideal silicone compound for reaction in the MMA/EGDM copolymerization system, whereas VTES is a suitable silicone comonomer for this system and it has been proved useful. Copyright © 2005 Society of Chemical Industry     

钢纤维聚合物混凝土抗压本构关系

钢纤维聚合物混凝土是由聚合物混凝土基体和钢纤维共同组成的纤维增强复合材料，它的力学行为不仅依赖于聚合物混凝土基体的行为，而且与钢纤维的掺量、分散特征以及钢纤维的几何尺寸有关，本文将基于损伤力学原理研究在不同纤维掺量下的钢纤维聚合物混凝土的全程压力-应变曲线及其本构模型。     

Heat and Mass Transfer Analogy Studies of Binary Liquid Mixture in Comparison with Eteanol-n-Heptane Evaporating to Air

An expenmental and theoretical study of heat and mass transfer analogy and a comparison of that to a binary liquid mixture evaporation is presented. Common organic solvents, ethanol and n-heptane, were used to form an alcohol - hydrocarbon mixture. Studies were carried out in a horizontal rectangular channel having air flow velocities of 0.2 - 0.9 m/s. Heat transfer coefficients were measured with a copper plate resistor and mass transfer coefficients with a square pool. The heat and mass transfer analogy is presented for a system having two evaporating compounds with a fixed value of air flow and verified by measuring and comparing mass transfer coefficients for distilled water with air flow velocities of 0.2 - 0.9 mls. An illustrative example of the use of the theory for industrial ventilation is presented.     

瓶组气化站的建筑、结构设计要点

瓶组气化站的建筑，结构设计关系到安全，满足使用要求和投资的大小，本文根据多年的实践和最新的有关设计规范的要求，阐述瓶组气化站建筑，结构设计的要点。     

未知钍—铀比的误差分析

研究了在任意Th、U含量和Th-U比覆盖整个范围(即0≤Th/U≤∝)时总α计数率对年剂量的转换因子及其误差。结果表明,当不测定Th-U比而只测量总α计数率时,最终引起的年龄误差对0≤Th/U≤∝来说为±5.1％-±8.3％,对1.1≤Th/U≤9.5来说只有±2.5％％-±4.1％。