可燃气体冷冻储存安全性分析

根据烃类和其它可燃气体液化储存的特性，比较了气体液化冷冻储存和压力液化储存在设备出现泄漏时的可燃气体释放量、释放速率和扩散范围指出，可燃气体液化冷冻储存与压力液化储存相比。储存压力低，即使出现泄漏，因其泄漏量少。泄漏速率低，扩散范围小，因而可燃气体液化冷冻储存比压力液化储存更为安全。     

Effects of gibberellic acid (GA3) on strawberry PAL (phenylalanine ammonia-lyase) and TAL (tyrosine ammonia-lyase) enzyme activities

Gibberellic acid (GA₃) treatments (30 and 60 μg litre⁻¹) were applied to young plants (Fragaria ananassa cv Chandler). Fruits were harvested at various developmental stages (14, 21, 28 and 35 days from fruit set). Weight and size, phenolic compounds (total polyphenols and anthocyanins) and enzyme activities, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) were determined. Our aim was to obtain detailed information about PAL and TAL activities related to the strawberry colour during development and ripening processes and to determine the effects of exogenous treatments of GA₃ on PAL and TAL activities. Exogenous treatments of GA₃ improve weight, size and colour of strawberry fruits, and affect PAL and TAL activities. We found that the anthocyanin content and PAL activity are enhanced by the exogenous treatment of GA₃ in the range of 30 μg litre⁻¹. However, with the higher GA₃ treatment, only the anthocyanin content is affected in that way. These findings suggest that gibberellic acid effect on PAL, TAL and ultimately anthocyanin enhancement is dosage related and saturation of the response occurs at 30 μg litre⁻¹. © 1998 SCI.     

水下自激脉冲射流喷嘴的吸气性能试验研究

运用自行研制的试验装置对水下不同结构参数的自激吸气脉冲射流喷嘴的吸气性能进行试验,研究了喷嘴的上下喷嘴直径、腔径和腔长等不同的组合配比对喷嘴吸气量的影响,以及喷嘴吸气量对喷嘴冲击性能的影响。结果表明:喷嘴吸气是提高水下自激脉冲射流冲击性能的有效途径,喷嘴的相对冲击力随着喷嘴吸气量的增加而提高;在较优的喷嘴结构参数配比范围内,喷嘴的吸气比率最大;最佳吸气比率的喷嘴面积比、相对腔长和相对腔径配比范围分别为3.5~4.0、8~9、11~12.5。     

THERMAL AND MASS DIFFUSIVITY FROM DYNAMIC SINGLE PELLET EXPERIMENTS

The single-pellet moment techniques previously developed for the evaluation of effective diffusion coefficient and effective thermal conductivity of a porous solid are combined and a procedure is proposed for the simultaneous evaluation of these constants from a single set of pulse response experiments. It is shown that both temperature and concentration response curves can be measured from a single pulse of oxygen injected into hydrogen carrier gas flowing past a catalyst pellet. It is shown that the zeroth moment of the concentration response peaks are sufficient for finding the effective diffusivity while both zeroth and first order moments are required for thermal conductivity. Experiments conducted at 110^°C with a boehmite pellet of porosity 0.57 gave a thermal conductivity value of 3.6 x 10^-4 cal/cm ^°K s and an effective diffusivity (for H₂O) of 0.054 cm2/s. The adsorption equilibrium constant of H₂O was determined as ρ_pK = 24.5 from the first moment data. If sorption resistance to diffusion through the pellet is included in the diffusion coefficient, an apparent value of 0.0011 cm2/s would be obtained for D_eff. This result indicates the importance of separation of diffusion and sorption parameters in the analysis.     

Automatic parameter tuning for functional regionalization methods

The methods used to define functional regions for public statistics and policy purposes need to establish several parameter values. This is typically achieved using expert knowledge based on qualitative judgements and lengthy consultations with local stakeholders. We propose to support this process by using an optimization algorithm to calibrate any regionalization method by identifying the parameter values that produce the best regionalization for a given quantitative indicator. The approach is exemplified by using a grid search and a genetic algorithm to configure the official methods employed in the UK and Sweden for the definition of their respective official concepts of local labour markets.     

Hydroprocesssing of light gas oil — rape oil mixtures

Two series of experiments of hydroprocessing of light gas oil - rape oil mixtures were carried out. The reactor feed was composed of raw material: first series — 10 wt.% rape oil and 90 wt.% of diesel oil; second series — 20 wt.% rape oil and 80 wt.% of diesel oil.     

Modulation of the antioxidant/pro-oxidant balance,cytotoxicity and antiviral actions of grape seed extracts

Grape seed extracts (GSEs) were investigated in yeast cells harbouring defects in their antioxidant system (regarding the cellular growth and growth recovery from H₂O₂ insult). GSEs antioxidant activity was detected in wild-type and mutant strains Δcta1, Δgsh1 and Δoye2glr1, while pro-oxidant activity in Δsod1 cells was seen. Assessment of proliferation of prostate cancer PC3 and HBV-replicating HepG2 2.2.15 cells treated with GSEs has shown higher cytotoxicity of red grape seed extract (RW) than white grape seed extract (WW) subjective to dose and period of administration. No antiviral effect was detected by measuring the secreted virion particles in HepG2 2.2.15 cells treated with GSEs. The GSEs play a dual antioxidant/pro-oxidant role in vivo according with the cellular antioxidant system deficiencies and exhibit cytotoxic properties in PC3 and HepG2 2.2.15 cell lines, but no antiviral action against HBV.     

金红石型高品质二氧化钛的制备

钛白粉具有良好的光学特性、易分散性、耐老化性和化学稳定性,在造纸行业有着广泛的应用。本文介绍了纳米金红石型二氧化钛的性质、生产方法,并主要探索采用硫酸法制备纳米金红石型二氧化钛,采用马尔文激光粒度分析仪、扫描电镜、透射电镜和X-射线衍射仪对实验产物进行表征。实验结果表明,该方法制得的二氧化钛具有较小的粒径以及较好的白度。     

Simulation of stochastic metal-forming process for rigid-viscoplastic material

Numerical solution of stochastic metal-forming process is analysed. The theoretical formulation is described which presents probabilistic distributions for velocities and strains taking into account random initial and boundary conditions. Finite element equations for rigid-viscoplastic materials are solved for the first two probabilistic moments of the random velocity field. The example of ring compression with random parameters is presented.