For direct quantitative determination of rare earth elements（REE） in REE-rich minerals, a most acceptable reference material NIST 610 might be an alternative external calibration standard due to the lack of matrix-m...For direct quantitative determination of rare earth elements（REE） in REE-rich minerals, a most acceptable reference material NIST 610 might be an alternative external calibration standard due to the lack of matrix-matched reference materials. Here, we aimed to develop an analytical method for direct quantitative determination of REE concentrations in REE-rich minerals via laser ablation-inductively coupled plasma-mass spectrometry（LA-ICP-MS）. The results show that the REE concentrations measured via LA-ICP-MS using NIST 610 as an extemal standard are in good agreement with reference values with relative percentage difference（Dr） mainly less than 15%. Overall, these results demonstrate that our proposed analytical method is robust and accurate for direct quantitative determination of REE concentrations in REE-rich minerals.展开更多
API 610《Centrifugal Pumps for Petroleum,Petrochemical and Natural Gas Industries》在国内石油、石化以及天然气等行业已执行多年,但对该标准的认识与理解存在差异,甚至执行偏离。介绍了API 610的适用范围,从相关词语的翻译理解...API 610《Centrifugal Pumps for Petroleum,Petrochemical and Natural Gas Industries》在国内石油、石化以及天然气等行业已执行多年,但对该标准的认识与理解存在差异,甚至执行偏离。介绍了API 610的适用范围,从相关词语的翻译理解、标准规定的技术要求重点、泵体承压件最低设计压力等级规定、应限定泵构件用高强度钢硬度以及不能忽视泵配套基础底座的刚度等方面对API 610进行了探讨。展开更多
Differential scanning calorimetry was used to study the crystallization and melting of nylon 610. For nylon 610 crystallized from the melt state (260 degrees C), the overall rate of bulk crystallization can be describ...Differential scanning calorimetry was used to study the crystallization and melting of nylon 610. For nylon 610 crystallized from the melt state (260 degrees C), the overall rate of bulk crystallization can be described by a simple Avrami equation with Avrami exponent n approximate to 2, independent of crystallization temperature. With the experimentally obtained T-m(0) (235 degrees C similar to 255 degrees C) of nylon 610, the fold surface free energy a, was determined to be 35 similar to 38 erg/cm(2). The effects of annealing temperature and time on the melting of quenched nylon 610 were also investigated. For nylon 610 quenched at room temperature there is only one DSC endotherm peak DSC scans on annealed samples exhibited an endotherm peak at approximately 10 degrees C above the annealing temperature. The size and position of the endothermic peak is strongly related to annealing temperature and time. An additional third melting was observed when quenched nylon 610 was annealed at high temperature for a sufficiently long residence time. The existence of the third melting peak suggests that more than one kind of distribution of lamella thickness may occur when quenched nylon 610 is annealed. The implications of these results in terms of crystal thickening mechanism were discussed.展开更多
文摘以经产荷斯坦奶牛外周血白细胞为材料,分离Poly(A)+ RNA,反转录合成单链及双链cDNA,经酶切成平均大小为400～600 bp的片段,将患乳房炎奶牛cDNA分成2组,分别与2种不同的接头连接,再与健康奶牛cDNA进行2次消减杂交和2次抑制性PCR扩增,将第2次PCR产物与pGEM-T载体连接,转化大肠杆菌TOP10感受态细胞进行文库扩增,构建了具有高消减效率的奶牛乳房炎抗性相关cDNA文库.文库扩增后得到610个白色阳性克隆,随机挑选克隆进行PCR鉴定,插入片段主要分布在250～750 bp 之间.文库的成功构建为进一步筛选、克隆与奶牛乳房炎抗性相关的基因奠定了基础,对研究奶牛乳房炎抗性的分子机制以及乳房炎的综合防制具有重要意义.
基金Supported by the National Natural Science Foundation of China（No.41603025）, the National Key Scientific Instrument and Equipment Development Projects of China（No.2015311007） and the China Postdoctoral Science Foundation（No.2016M602386）.
文摘For direct quantitative determination of rare earth elements（REE） in REE-rich minerals, a most acceptable reference material NIST 610 might be an alternative external calibration standard due to the lack of matrix-matched reference materials. Here, we aimed to develop an analytical method for direct quantitative determination of REE concentrations in REE-rich minerals via laser ablation-inductively coupled plasma-mass spectrometry（LA-ICP-MS）. The results show that the REE concentrations measured via LA-ICP-MS using NIST 610 as an extemal standard are in good agreement with reference values with relative percentage difference（Dr） mainly less than 15%. Overall, these results demonstrate that our proposed analytical method is robust and accurate for direct quantitative determination of REE concentrations in REE-rich minerals.
文摘API 610《Centrifugal Pumps for Petroleum,Petrochemical and Natural Gas Industries》在国内石油、石化以及天然气等行业已执行多年,但对该标准的认识与理解存在差异,甚至执行偏离。介绍了API 610的适用范围,从相关词语的翻译理解、标准规定的技术要求重点、泵体承压件最低设计压力等级规定、应限定泵构件用高强度钢硬度以及不能忽视泵配套基础底座的刚度等方面对API 610进行了探讨。
基金This work is sponsored by The National Natural Science Foundation of China.
文摘Differential scanning calorimetry was used to study the crystallization and melting of nylon 610. For nylon 610 crystallized from the melt state (260 degrees C), the overall rate of bulk crystallization can be described by a simple Avrami equation with Avrami exponent n approximate to 2, independent of crystallization temperature. With the experimentally obtained T-m(0) (235 degrees C similar to 255 degrees C) of nylon 610, the fold surface free energy a, was determined to be 35 similar to 38 erg/cm(2). The effects of annealing temperature and time on the melting of quenched nylon 610 were also investigated. For nylon 610 quenched at room temperature there is only one DSC endotherm peak DSC scans on annealed samples exhibited an endotherm peak at approximately 10 degrees C above the annealing temperature. The size and position of the endothermic peak is strongly related to annealing temperature and time. An additional third melting was observed when quenched nylon 610 was annealed at high temperature for a sufficiently long residence time. The existence of the third melting peak suggests that more than one kind of distribution of lamella thickness may occur when quenched nylon 610 is annealed. The implications of these results in terms of crystal thickening mechanism were discussed.
