Chironomids fail to emerge from LAS-contaminated water

The effect of the surfactant LAS was investigated on chironomid emergence using six outdoor artificial channels. The concentrations of LAS were mostly between 1 and 2 mgl^-1 in the three treated channels. Chironomus yoshimatsui, Cricotopus tamapullus, Eukiefferiella coerescens, Eukiefferiella sp. and Thienemanniella majuscula were the major chironomids obtained with emergence traps. The number of midges trapped did not differ significantly between the treatment and the control for either of the species. On the other hand, the ratios of midges failing to emerge to the total midges trapped was significantly higher in the treatment than in the control for all of the species. The results show that chironomids emergence is difficult as a result of LAS treatment probably due to the lowered surface tension.     

Differences in Hepatic Microsomal Cytochrome P-450 Isoenzyme Induction by Pyrazole, Chronic Ethanol, 3-Methylcholanthrene, and Phenobarbital in High Alcohol Sensitivity (HAS) and Low Alcohol Sensitivity (LAS) Rats

High and low alcohol sensitivity (HAS and LAS) rats have been selected for their differences in ethanol-induced sleep time. Liver monooxygenase activities were studied in HAS and LAS rats before and after treatments with known inducers such as chronic ethanol, pyrazole, 3-methylcholanthrene (3-MC) and phenobarbital (PB) to determine whether the selection procedure also selected for differences in the cytochrome P-450 (P-450) inducibility. This previously has been shown with long sleep (LS) and short sleep (SS) mice, which were selected using a similar criterion. 3-MC and PB, in conjunction with chronic ethanol treatment, were used in order to evaluate the interactions of ethanol with these inducers. Prior to treatment, total P-450 content was slightly lower in LAS than in HAS rats. However, both lines displayed the same microsomal monooxygenase activities related to different P-450 isozymes. This was demonstrated by ethoxyresorufin deethylation (EROD) for cytochrome P-450 1A1 (CYP1A1), acetanilide hydroxylation (ACET) for CYP1A2, pentoxyresorufin dealkylation (PROD) for CYP2B, 1-butanol oxidation (BUTAN) and N-nitrosodimethylamine demethylation (NDMA) for CYP2E1. After the different treatments, HAS rats did not differ from LAS rats in their CYP2E1 inducibility. However, pyrazole, PB and 3-MC treatment led to differences in CYP1A and CYP2B monooxygenase activities between the two lines. The enhancement of PROD by pyrazole treatment was less prominent in LAS (1.7-fold of the control value) than in HAS rats (3.8-fold).(ABSTRACT TRUNCATED AT 250 WORDS)     

氧化钾的含量对牙科微晶玻璃析晶性能的影响

目的 研究氧化钾（K2O）的含量对牙科微晶玻璃析晶性能的影响。方法 在Li2O-SiO2-Al2O3-P2O5-ZnO体系的基质玻璃中添加不同含量的K2O,根据差热分析（DTA）曲线确定微晶玻璃的热处理制度,采用X射线衍射分析和扫描电子显微镜（SEM）观测来比较不同的K2O含量对牙科Li2O-SiO2-Al2O3-P2O5-ZnO体系微晶玻璃析晶成分和显微结构的影响。结果 K2O的引入有助于降低玻璃基体的粘度,促进基质玻璃的析晶。在基质玻璃中添加5.3 wt%的K2O可以使玻璃在热处理后析出较多的二硅酸锂晶体,晶体呈板条状,长度约为4 μm,在玻璃基质中分布均匀。 结论 添加一定量的K2O有助于提高牙科Li2O-SiO2-Al2O3-P2O5-ZnO体系微晶玻璃的析晶性能。     

泡沫分离技术的研究——Ⅰ.脱除废水中的表面活性剂

采用泡沫分离技术,研究了从洗涤剂工厂废水中脱除直链十二烷基苯磺酸钠(LAS)的过程。采用流动法测定了LAS-H_2O系统中LAS的临界胶束浓度和LAS-H_2O-NaCl系统的表面过剩浓度。以旋转圆盘作为消泡器,探讨了提馏操作型泡沫塔中各种操作参数(如进料浓度、气液比、逆流泡沫段高度、添加剂NaCl等)对分离效果的影响,获得了该系统的适宜操作条件、泡沫排液模型的数学表达式、传质单元高度以及消泡过程中衡量消泡效果的“冷凝因子”与圆盘转速之间的关系。结果表明:该技术具有分离因子大、耗能少、简单易行等优点,可望有效地脱除废水中的表面活性剂。