Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the additio...Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus,展开更多
目的:了解某一批次聚对苯二甲酸乙二醇酯(polyethylene terephthalate,PET)瓶装无气天然矿泉水产生异味的缘由。方法:首先采用膜过滤结合平板菌落计数法分离和计数污染菌,16S r RNA序列分析鉴定其为假单胞菌属(Pseudomonas spp.),再采...目的:了解某一批次聚对苯二甲酸乙二醇酯(polyethylene terephthalate,PET)瓶装无气天然矿泉水产生异味的缘由。方法:首先采用膜过滤结合平板菌落计数法分离和计数污染菌,16S r RNA序列分析鉴定其为假单胞菌属(Pseudomonas spp.),再采用假单胞菌属特异性rpo B引物进行梯度聚合酶链式反应优化扩增条件,产物进行测序和序列分析将污染菌鉴定到种。结果:这批产品的主要污染菌是一种2009年从南极分离鉴定的假单胞菌属新种P.extremaustralis。反接实验证实该菌能在天然矿泉水中生长繁殖,并产生刺激性异味。结论:P.extremaustralis部分细菌能够透过两级串联0.2μm过滤器,耐受中、低压紫外杀菌工艺,耐低温和低氧压,能在无任何添加的PET瓶装无气天然矿泉水中生长并产生异味。展开更多
文摘Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus,