加糖对自酿葡萄酒理化性质的影响

以山葡萄为材料,通过模拟家庭自酿葡萄酒的酿制过程,探究加糖（冰糖和砂糖）对自酿葡萄酒中酒精度以及糖类、总酸、甲醇和杂醇油含量的影响.结果表明：自酿葡萄酒时加糖显著降低了酒液的酸度,且酒液中总糖和还原糖含量较对照组均显著增加;冰糖组和砂糖组酒液中甲醇含量均显著高于对照组,但3组的甲醇含量均符合国家标准（国家标准≦0.4 mg/mL）;酒液中杂醇油含量在国家规定含量（白酒的杂醇油标准≦2.00 mg/L）范围内;不同加糖方式与甲醇含量存在显著相关性,自酿葡萄酒时加糖量应≦1∶10.     

Emergence of vancomycin tolerance in Streptococcus pneumoniae.

Streptococcus pneumoniae, the pneumococcus, is the most common cause of sepsis and meningitis. Multiple-antibiotic-resistant strains are widespread, and vancomycin is the antibiotic of last resort. Emergence of vancomycin resistance in this community-acquired bacterium would be catastrophic. Antibiotic tolerance, the ability of bacteria to survive but not grow in the presence of antibiotics, is a precursor phenotype to resistance. Here we show that loss of function of the VncS histidine kinase of a two-component sensor-regulator system in S. pneumoniae produced tolerance to vancomycin and other classes of antibiotic. Bacterial two-component systems monitor environmental parameters through a sensor histidine-kinase/phosphatase, which phosphorylates/dephosphorylates a response regulator that in turn mediates changes in gene expression. These results indicate that signal transduction is critical for the bactericidal activity of antibiotics. Experimental meningitis caused by the vncS mutant failed to respond to vancomycin. Clinical isolates tolerant to vancomycin were identified and DNA sequencing revealed nucleotide alterations in vncS. We conclude that broad antibiotic tolerance of S. pneumoniae has emerged in the community by a molecular mechanism that eliminates sensitivity to the current cornerstone of therapy, vancomycin.     

混凝土防渗渠道措施探讨

本文总结了渠道混凝土防渗衬砌形式,对混凝土防渗渠道特点进行了分析,根据工程实际运用情况,说明渠道防渗由单一材料向复合材料、单一结构向复合结构发展的趋势。