不同实验条件对静注人免疫球蛋白(pH 4)多聚体含量的影响

目的考察不同实验条件对静注人免疫球蛋白(pH 4)多聚体含量的影响及多聚体含量增加对家兔存活状态的影响。方法取静注人免疫球蛋白(pH 4),经干热破坏试验、湿热加速试验、紫外线照射试验、X射线照射试验及冰冻破坏试验,观察不同实验条件对其多聚体含量的影响;并取湿热加速试验和冰冻处理的样品注射家兔,观察多聚体含量增加对家兔存活状态的影响。结果静注人免疫球蛋白(pH 4)的多聚体含量随贮存温度的升高、时间的延长而增加,紫外线、X射线照射及冰冻处理均不影响多聚体含量;多聚体含量愈高,家兔存活状态愈差,多聚体含量达80%以上时,可致家兔死亡。结论高温可显著影响多聚体含量,多聚体含量增加与家兔存活状态呈负相关。     

预培养对酸奶冻干发酵剂活力的影响

研究了预培养对酸奶冻干发酵剂活力的影响。在不同的温度和时间下，对酸奶冻干发酵剂的悬浮液进行预培养，得出当温度为42℃时培养40min，冻干发酵剂菌体存活率可以从71％提高到82％，凝乳时间可以从210min降低到185min。在4℃经90d贮藏稳定性实验，发酵剂中菌种的存活率为62％，凝乳时间为245man，较对照存活率提高了23％，凝乳时间缩短了45min。     

Effect of cryoprotective agents on survival and stability of Lactobacillus acidophilus cultured in food‐grade medium

The effect of cryoprotectants on survival and stability of freeze‐dried Lactobacillus acidophilus ATCC‐4962 cultivated in food‐grade medium was evaluated. The food‐grade medium employed was more economical than the commercial de Man Rogosa and Sharpe medium and gave a higher yield of L. acidophilus ATCC‐4962. Cryoprotective agents improved significantly the cell viability. Skim milk, skim milk with malt extract and monosodium glutamate provided significantly higher viable counts, at optimum concentration of 0.3%. At higher concentration, there was a reduction in cell viability, attributed to cell shrinkage associated with osmotic pressure changes inside the cells. Lactobacillus acidophilus ATCC‐4962 was stable at 28°C until 8 weeks.     

In vitro irradiation station for broad beam radiobiological experiments

The study of the interaction of charged particles with living matter is of prime importance to the fields of radiotherapy, radioprotection and space radiobiology. Particle accelerators and their associated equipment are proven to be helpful tools in performing basic science in all these fields. Indeed, they can accelerate virtually any ions to a given energy and flux and let them interact with living matter either in vivo or in vitro. In this context, the University of Namur has developed a broad beam in vitro irradiation station for use in radiobiological experiments. Cells are handled in GLP conditions and can be irradiated at various fluxes with ions ranging from hydrogen to carbon. The station is mounted on a 2 MV tandem accelerator, and the energy range can be set up in the linear energy transfer (LET) ranges that are useful for radiobiological experiments. This paper describes the current status of the hardware that has been developed, and presents results related to its performance in term of dose-rate, energy range and beam uniformity for protons, alpha particles and carbon ions. The results of clonogenic assays of A549 lung adenocarcinoma cells irradiated with protons and alpha particles are also presented and compared with literature.     

黄蘑多糖对受X射线照射小鼠的防护作用

本文观察了预防给予黄蘑多糖对受Ｘ射线照射小鼠的保护作用及其对免疫功能的影响。结果表明，黄蘑多糖可明显提高受８．０ＧｙＸ线照射小鼠３０日存活率，保护指数可达１．７２，防护效果与人参多糖相近。另外，黄蘑多糖可显著增强受２．０Ｇｙ照射小鼠脾脏淋巴细胞产生ＩＬ－２和γＩＦＮ的能力，激活脾脏ＮＫ细胞，加速胸腺细胞周期进程。说明黄蘑多糖对受Ｘ线照射小鼠有一定的防护作用，可明显增强其免疫功能。     

Regression approach to tire reliability analysis

The paper considers an empirical approach to the root-cause analysis of a certain kind of automobile tire failure. Tire life data are obtained from a laboratory test, which is developed to duplicate field failures. A number of parameters related to tire geometry and physical properties are selected as explanatory variables that potentially affect a tire's life on test. Analysis of the life test data is performed via the Cox survival regression model. The paper also elaborates on the application of an ordinary (non-survival) linear regression to modeling the failure initiation and propagation. The developed statistical models help to identify the elements of tire design affecting the probability of tire failure due to the failure mode in question.     

Survival of salmonellae in bio-yoghurt

Many yoghurt-like products are sold with pH values of 4.5–4.6, and a potential pathogen, Salmonella infantis , was shown to survive for 10 days in typical commercial samples of 'bio-yoghurt'. Another servovar, Salmonella hadar , could not be detected after 48 h in similar products. The need to avoid contamination during the manufacture of fermented milks with pH values above those traditionally associated with yoghurt (~4.0) is stressed.     

Survival of the House Dust Mite,Dermatophagoides farinae,at High Temperatures (40–80°C)

Abstract Experiments were conducted to evaluate the survival time of randomly selected female D. farinae exposed to temperatures from 40 to 80°C and relative humidities (RHs) between 10 and 90%. Significant temperature effects were found on the length of time mites can survive under those conditions. The time needed to induce 100% mortality for female D. farinae held at 40°C varied between 39 and 84 h. At 70 and 80°C, all mites died within 5 minutes. At 50°C and above, RH had little influence and temperature alone was the determining factor for mite survival. The length of survival time decreased precipitously between 40 and 50°C, suggesting that a loss of physiological integrity of female D. farinae probably occurred in this range. The results of this study indicated that the technique of raising temperatures to above 40°C for a short duration can be used to reduce living house dust mite populations in homes significantly.     

从在研课题看园林科研

根据17家园林科研院所2003年在研课题的情况,初步总结了目前园林科研的主要特点.认为提高园林科研课题的水平,增强科研院所的生存力是当务之急,并提出了提高园林科研水平的建议.     

In situ aquatic bioassessment of pesticides applied on rice fields using a microalga and daphnids

This study assessed the effects of episodic contamination on a drainage canal adjacent to an area of intensive rice production (Coimbra, Portugal). Four monitoring periods were considered [i) before herbicide application (day -14), ii) at the first application day (day 0), iii) 3 or 5 and iv) 6 days after]. Each one consisted in three complementary evaluation lines: a) physico-chemical analyses, b) whole effluent toxicity (WET) assays with Pseudokirchneriella subcapitata, c) in situ bioassays to assess microalgae (P. subcapitata) growth, and the feeding rate and survival of Daphnia longispina and Daphnia magna. Study sites were located upstream, in a protected wetland (L1), and downstream, in the vicinity of rice fields (L2). Along with the application of agrochemicals, there was a general decrease of the water quality, especially in L2, due to nutrient and herbicide inputs. Herbicide peaks (on days 0, 5 and 6) in L2 water samples were recorded concomitantly or immediately after their application. Regarding the in situ bioassessment, the algae growth decrease from day 0 onwards in L1, whilst in L2 its inhibition was generally coherent with the decline of the water quality. Apparently, WET tests indicated that the limitation of nutrients could be affecting algae growth in L1, however, conclusions should be cautious. The feeding depression of daphnids occurred on days 0 and 5 for D. longispina and only on day 0 for D. magna, while significant reductions on survival were restricted to day 0 for both species. The impairments occurring on day 0 were linked to a potential increased toxicity driven by the ingestion of particle-bound herbicides and suspended particles. The feeding rate of daphnids provided an earlier indication of toxic impairments, though it is prompted the use of complementary endpoints and trophic levels in order to understand the cumulative effects due to various herbicide pulses.