用边际分析理论评价老区增产措施

为了正确评价和筛选老油气区的增产措施，除了优选地质和油藏条件外，还应从经济角度加以论证，根据边际分析理论，提出了两种计算增产措施边际成本的方法，分别适合于实际资料丰富和缺乏的情况，并根据边际成本等于边际效益的原则，确定出老区增产措施的边际价格以及在现行价格体系下各项措施的取舍条件。由此，对增产措施进行评价，优选出地质及工艺上可行的、经济效益好的项目。实践证明，本方法是可行的。     

Evaluation of a single plate microbiological growth inhibition assay as a screening test for the presence of antimicrobial agents in compound animal feedingstuffs at therapeutic and contaminating concentrations

The Inhibitory Substance Test (IST), a microbiological growth inhibition test, is used for screening animal feedingstuffs for the presence of (contaminating) antimicrobial compounds. The effectiveness of the IST was established for 33 compounds that may be incorporated in feedingstuffs. Minimum detectable concentrations (MDCs) for standard solutions were established and compared with those obtained following solvent extraction of an antimicrobial-free compound feedingstuff spiked with each compound at 0-20mg/kg. Of the 33 standard solutions examined, the test organism was not sensitive to 11 and the MDC for one was greater than its maximum inclusion rate in complete feedingstuffs. Following routine extraction (25% acetone-phosphate buffer) of feedingstuffs spiked with each of the 22 compounds to which the organism was sensitive, 10 were not detected, 15 were detectable at both minimum and maximum feed-inclusion rates and four were only detectable at their maximum feed-inclusion rates. Extraction with methanol (25% ) had a deleterious effect with 12 compounds not detected, nine detectable at both minimum and maximum feed-inclusion rates and five detectable at their maximum feed-inclusion rates. Increasing acetone and methanol concentrations to 40 and 55% respectively resulted in larger inhibitory zones for antibiotic-free feedingstuff (25 : 3 + 2 : 43mm vs 21 : 1 + 1 : 02mm) compared with both 25% acetone (11 : 3 + 0 : 22mm) and 25% methanol (11 : 2 + 0 : 22mm), requiring the establishment of greater threshold zone diameters and negating any advantage in increasing the solvent concentration under these test conditions. It is concluded that the IST may be particularly useful for detection of a number of the zootechnical feed-additives recently banned in the EU, which, if used illegally, may be present at sufficiently high inclusion rates to facilitate detection. Further alteration of extraction conditions may improve the scope of the assay.     

产脂肽生物表面活性剂细菌的筛选及培养基优化

利用变色圈法和噬油斑法从土壤样品中分离筛选出一株产生物表面活性剂的细菌菌株LB345,通过薄层层析(TLC)确定其所产生物表面活性剂为脂肽,并通过单因素实验及L9(34)正交实验对菌株的培养基配方进行了优化,确定优化培养基的组成(g/L):葡萄糖30,NaNO32,KH2PO410,Na2HPO410,FeSO42.5×10-4,MgSO4.7H2O 0.03,NaC l 5,CaC l20.4,酵母粉0.3,初始pH值5,培养温度37℃,发酵时间7 d。在上述条件下,菌株LB345的脂肽产量可达到0.7 g/L。     

New model of screening kinetics

An understanding of screening requires a knowledge of screening kinetics. The new model of screening kinetics presented in this paper is theoretically described and experimentally proven. Samples of different raw materials, different in their density, bulk density, particle size distribution and particle shape, were used.The conducted experiments confirmed that the new model of screening kinetics successfully describes the process of screening of various raw materials even when they are exposed to a range of factors that most influence the screening process (dimensions of the screen, particle size distribution of raw materials, particle shape, and thickness of the bed on the screen).The advantage of this model of screening kinetics lies in its simplicity as it is characterized by the fact that it has only one parameter, i.e., (k) - the screening rate constant, which is experimentally measured. This constant can be measured on the basis of a single screening experiment. This fact is very significant for practical applications of the model to an industrial screen.     

田湾核电厂址事故后果评价中天气取样方案的比较研究

本文基于田湾核电厂址1998年9月1日至1999年8月31日一整年的逐时气象数据、SF6实测扩散参数和评价区(40km×40km)各网格(2km×2km)人口分布等实测资料,对依据秦山、田湾核电厂址和惠安拟选核电厂址多年逐时气象数据统计分析后提出的五个天气取样候选方案,估算了某假想事故在评价区内造成的集体剂量,得到事故集体剂量余补累积概率分布函数(即CCFD曲线)。同时应用整年“逐时滑移”事故释放起始时刻方法计算了事故集体剂量的CCFD曲线,即“标准”CCFD曲线,并将五类天气取样候选方案获得的95%累积概率水平事故集体剂量值与由“标准”CCFD曲线得到的相应值作比较。结果表明,天气取样候选方案四最佳,此方案给出的95%累积概率水平事故集体剂量与由“标准”CCFD曲线得到的相应值的相对偏差仅为3%。     

Quick Analysis Methods for Random Balance,Screening Experiments

A short expository account of random balance ia given, in which some different types of sampling are distinguished. As a quick significance test of effectiveness of single factors, a simple analysis of variance method is recommended. For the sake of sensitivity, it is suggested that the number of levels of quantitative factors should preferably be less than five. The degree of unbalance of a random balance design is studied, largely through an example, and a desirable upper bound is suggested for the number of levels of any factor, namely one eighth of the total number of observations.     

Glycerolipids as Selective Thrombin Inhibitors from the Fungus Stereum Hirsutum

ABSTRACT

A dry extract of Stereum hirsutum exhibited a significant inhibitory activity on thrombin (34%). A bioassay oriented fractionation of the extract of Stereum hirsutum has led to the isolation of two active fractions. On the basis of spectroscopic data, chemical reactions, and GC-MS analysis, complex mixtures of diacylglycerophospholipids (DAGPs) and diacylglycerols (DGs) have been isolated and identified. Docking studies suggest that some isolated compounds could bind to the thrombin active site in a similar manner as previously reported phosphonate thrombin inhibitors.