加拿大丹尼森矿业公司迅速扩大生产以满足长远需要

加拿大丹尼森(Denison)矿业公司为了满足从现在到2011年间供应一亿九千九百万磅U_3O_8的长远需要,已经大幅度地扩大了位于安大略省伊利湖以北10英里的所属地下矿山和选厂的生产,现在又在进一步实施一项分期扩建计划,以使矿山产量增加到22,000吨/日。丹尼森矿每周工作5天,1978年初的日出矿量已达10,000吨水平。丹尼森选厂经过扩建,日处理量已由1973年平均4,300吨提高到目前的7,100吨。     

Liquid chromatography-high resolution mass spectrometry analysis of fatty acid metabolism

We present a liquid chromatography/mass spectrometry (LC/MS) method for long-chain and very-long-chain fatty acid analysis and its application to (13)C-tracer studies of fatty acid metabolism. Fatty acids containing 14 to 36 carbon atoms are separated by C(8) reversed-phase chromatography using a water-methanol gradient with tributylamine as ion pairing agent, ionized by electrospray and analyzed by a stand-alone orbitrap mass spectrometer. The median limit of detection is 5 ng/mL with a linear dynamic range of 100-fold. Ratios of unlabeled to (13)C-labeled species are quantitated precisely and accurately (average relative standard deviation 3.2% and deviation from expectation 2.3%). In samples consisting of fatty acids saponified from cultured mammalian cells, 45 species are quantified, with average intraday relative standard deviations for independent biological replicates of 11%. The method enables quantitation of molecular ion peaks for all labeled forms of each fatty acid. Different degrees of (13)C-labeling from glucose and glutamine correspond to fatty acid uptake from media, de novo synthesis, and elongation. To exemplify the utility of the method, we examined isogenic cell lines with and without activated Ras oncogene expression. Ras increases the abundance and alters the labeling patterns of saturated and monounsaturated very-long-chain fatty acids, with the observed pattern consistent with Ras leading to enhanced activity of ELOVL4 or an enzyme with similar catalytic activity. This LC/MS method and associated isotope tracer techniques should be broadly applicable to investigating fatty acid metabolism.     

橡胶胶料挤出用的空气润滑型口型

导言胶料流经口型是橡胶挤出作业的一个重要步骤。在此过程中,口型将胶料形成所需要的形状。在很多情况下,挤出机的产量会受到口型中流动阻力的限制。此外,口型中过大的压力损失会导致胶料太高的温升,从而发生不希望的胶料交联。     

Small heat shock protein 27 (Hsp27) expression is highly induced in rat myometrium during late pregnancy and labour

The underlying mechanisms that regulate uterine contractions during labour are still poorly understood. A candidate regulatory protein is heat shock protein 27 (Hsp27). It belongs to the small heat shock protein family and can regulate actin cytoskeleton dynamics, act as a chaperone, and may regulate contractile protein activation. As a result, we hypothesized that Hsp27 expression would be highly induced during late pregnancy and labour. Hsp27 mRNA expression was significantly elevated (P <0.05) on days 17 to 22 of gestation. In addition, immunoblot analysis demonstrated that detection of total Hsp27 increased (P <0.05) between day 21 and 1 day post-partum (PP) inclusive. Since phosphorylation of Hsp27 has been reported to be a prerequisite for smooth muscle contraction, we examined the temporal and spatial expression of Ser-15 phosphorylated Hsp27. Immunoblot analysis showed that the detection of Ser-15 phosphorylated Hsp27 significantly increased (P <0.05) between days 19 and 23 (active labour) inclusive, in parallel with detection of total Hsp27. Immunocytochemical analysis of Ser-15 phosphorylated Hsp27 expression in situ demonstrated that phosphorylated Hsp27 in circular muscle became detectable in peri-nuclear and membrane regions on days 19 to 22, but was primarily restricted to the cytoplasm on days 23 to PP. In contrast, phosphorylated Hsp27 in longitudinal muscle was primarily detected in myocyte membranes on days 15 to 22, and then also became detectable in the cytoplasm of myocytes on days 23 and PP. Our results demonstrate that Hsp27 expression is highly upregulated during late pregnancy and labour and suggest that Hsp27 is a potential candidate contraction-associated protein.