适用于大斜度井及水平井钻进的MEG钻井液研究

大斜度井及水平井钻进的特点对钻井液的性能提出较高的要求.本文通过实验,研究出一种仿油性水基钻井液,该钻井液的流变性、滤失性以及抗温性能良好,并且具有类似油基钻井液的较好的页岩抑制性、储层保护特性及润滑性能,同时可以避免环境污染问题,是一种适用于大斜度井及水平井的钻进的钻井液.     

新型葡萄糖-2,5-二酮哌嗪衍生物的设计、合成与细胞毒活性

从海洋天然产物中挖掘高细胞毒活性化合物成为近年来抗肿瘤药物研究工作的一项重要内容。本研究以2,5-二酮哌嗪海洋天然产物Piperafizine B为修饰骨架,在其哌嗪环6位的苄叉邻位引入位阻较大的四乙酰基葡萄糖或葡萄糖基团,共合成了14个2,5-二酮哌嗪衍生物(1a-i,2a-f)。溶解性实验结果初步表明,相较于PiperafizineB,衍生物的脂溶性(1.5～27.9mg·mL^-1,溶剂为二甲亚砜(dimethylsulfoxide,DMSO))与水溶性(0.1～0.9mg·mL^-1,溶剂为磷酸缓冲液,pH7.4)均明显改善。衍生物的细胞毒活性评价结果表明,部分四乙酰基萄糖衍生物的细胞毒活性较好,半抑制率浓度值(IC50)为1.0～9.1μmol·L^-1,并对Huh-7细胞的生长抑制活性具有一定的选择性(3.3～4.5μmol·L^-1)。化合物1c的细胞毒活性最好,对癌细胞株K562、A549及Huh-7的IC50值分别为1.0、3.6与3.3μmol·L^-1。而将乙酰基水...     

Culture medium optimization for pigment production with RSM method

Response surface methodology was used to optimize a medium for a red-pigmented marine bacterium S-9801 strain （Flavobocterium sp.）. In the first optimization step the influence of yeast extract, peptone, glucose and sodium chloride on pigment production was evaluated using a fractional factorial design. Pigment production was positively influenced by glucose and sodium chloride while other components had no significant effect. In the second step the path of steepest ascent was used to approach the optimal region of the medium composition. In the third step the optimal concentration of glucose and sodium chloride was determined by a central composite design and response analysis. The optimized medium allowed pigment production （A 535-650） to be increased from 0.137 to 0.559, being 320% higher than the original medium.     

两院院士评选中国世界十大科技进展新闻揭晓

由中国科学院、中国工程院主办的中国科学院院士和中国工程院院士评选的2014年中国十大科技进展新闻、世界十大科技进展新闻近日在京揭晓。2014年中国十大科技进展新闻是:探月工程三期再入返回飞行试验获圆满成功,4500米级深海遥控作业型潜水器海试成功,量子通信安全传输创世界纪录,甲烷高效转化研究获重大突破,超级稻亩产首破千公斤,能量最高质子回旋加速器首次出束,首次获人源葡萄糖转运蛋白结构,光通信     

缺少深度睡眠将增大Ⅱ型糖尿病的风险

深度睡眠也称为“短波睡眠”。它是整个睡眠过程最有助于身体恢复良好状态的阶段。最近，来自芝加哥大学医学中心的研究者发现，当健康的年轻人有3个晚上的深度睡眠受到抑制时。他们的身体对胰岛素的敏感性就会降低。对血糖水平的调节能力将显著下降。这时，他们的身体需要更多的胰岛素来分解体内的葡萄糖，从而导致身体对葡萄糖的耐受性降低，增大了Ⅱ型糖尿病的风险。     

龙须菜UDP-葡萄糖焦磷酸化酶基因的克隆及其表达与琼胶产量的关系

对红藻龙须菜(Gracilarialei maneiformis)UDP葡萄糖焦磷酸化酶(UGPase)基因的表达与不同藻株中藻体琼胶产量之间的相关性进行研究。通过PCR扩增的方法得到了龙须菜UGPase的基因序列。该基因cDNA序列的全长为2 200 bp,开放阅读框1 485 bp,编码494个氨基酸;龙须菜UGPase基因的氨基酸序列与其它物种的UGPase氨基酸序列相似性较高;该基因是单拷贝的,缺乏内含子;具有特殊的加尾信号。利用荧光实时定量PCR的方法检测UGPase基因相对表达量。结果表明,该基因的表达与琼胶含量存在显著相关性,即在高琼胶组藻株中的表达量显著高于低琼胶组藻株,对琼胶含量高低具有指示作用,显示了在产业化应用中的潜能。     

微藻的异养培养及应用研究

微藻(microalgae)是一大类微观的以个体、链状或群体形式存在的单细胞藻类,大小从几微米到几百微米不等。微藻种类繁多,据估计大约有200 000-800 000种,其中已有记录的有35 000多种[1]。     

Effect of carbon source on growth and lipid accumulation in <Emphasis Type="Italic">Chlorella sorokiniana</Emphasis> GXNN01

Heterotrophic culture of microalgae to develop methods of increasing biomass productivity and storage lipids has brought new insight to commercial biodiesel production. To understand the relationship between heterotrophy and lipid production, the effects of carbon sources on the growth and lipid accumulation of Chlorella sorokiniana GXNN01 was studied. The alga exhibited an increased growth rate in response to the addition of carbon sources, which reached the stationary phase after 48 h at 30°C. In addition, glucose and NaAc had a significant effect on the lipid accumulation during the early-stationary phase. Specifically, the lipid content was 0.237±0.026 g g⁻¹ cell dry weight and 0.272±0.041 g L⁻¹ when glucose was used as the carbon source, whereas the lipid content reached 0.287±0.018 g g⁻¹ cell dry weight and 0.288±0.008 g L⁻¹ when NaAc was used as the carbon source. The neutral lipid content was found to first decrease and then increase over time during the growth phase. A glucose concentration of 20 mmol L⁻¹ gave the maximal lipid yield and the optimum harvest time was the early-stationary phase.