高效液相色谱串联质谱法测定水产品中氟喹诺酮类药物残留的不确定度评定

建立高效液相色谱串联质谱法测定水产品中的氟罗沙星、氧氟沙星、诺氟沙星3种氟喹诺酮类药物残留量的测量不确定度评定方法。构建不确定度评定的数学模型，对不确定度来源进行分析。评定结果表明，不确定来源主要为标准溶液配制及标准曲线拟合。当水产品中氟罗沙星的质量分数为5.24μg/kg时，其扩展不确定度为0.83μg/kg(k=2)；氧氟沙星含量为5.34μg/kg时，其扩展不确定度为0.49μg/kg(k=2)；诺氟沙星含量为6.35μg/kg时，其扩展不确定度为1.20μg/kg(k=2)。     

Review of ultrafast spectroscopy studies of valley carrier dynamics in two-dimensional semiconducting transition metal dichalcogenides

The two-dimensional layered transition metal dichalcogenides provide new opportunities in future valley-based information processing and also provide an ideal platform to study excitonic effects. At the center of various device physics toward their possible electronic and optoelectronic applications is understanding the dynamical evolution of various manyparticle electronic states, especially exciton which dominates the optoelectronic response of TMDs, under the novel context of valley degree of freedom. Here, we provide a brief review of experimental advances in using helicity-resolved ultrafast spectroscopy, especially ultrafast pump–probe spectroscopy, to study the dynamical evolution of valley-related many-particle electronic states in semiconducting monolayer transitional metal dichalcogenides.     

关于多电离基团氨基酸的pI计算

一氨基一羧基氨基酸的 pI 值计算,在一般生化教科书中都有较详尽的论述和推导。根据滴定曲线的分析,很自然地得出这种氨基酸的等电点即正、负离子相等时的 pH.在这一 pH下,氨基酸主要是以两性离子状态存在,它所带的正电荷数等于负电荷数,净电荷为“零”。且     

Anisotropic photoresponse of layered rhenium disulfide synaptic transistors

Layered ReS₂ with direct bandgap and strong in-plane anisotropy shows great potential to develop high-performance angle-resolved photodetectors and optoelectronic devices. However, systematic characterizations of the angle-dependent photoresponse of ReS₂ are still very limited. Here, we studied the anisotropic photoresponse of layered ReS₂ phototransistors in depth. Angel-resolved Raman spectrum and field-effect mobility are tested to confirm the inconsistency between its electrical and optical anisotropies, which are along 120° and 90°, respectively. We further measured the angle-resolved photoresponse of a ReS₂ transistor with 6 diagonally paired electrodes. The maximum photoresponsivity exceeds 0.515 A·W^-1 along b-axis, which is around 3.8 times larger than that along the direction perpendicular to b axis, which is consistent with the optical anisotropic directions. The incident wavelength- and power-dependent photoresponse measurement along two anisotropic axes further demonstrates that b axis has stronger light-ReS₂ interaction, which explains the anisotropic photoresponse. We also observed angle-dependent photoresistive switching behavior of the ReS₂ transistor, which leads to the formation of angle-resolved phototransistor memory. It has simplified structure to create dynamic optoelectronic resistive random access memory controlled spatially through polarized light. This capability has great potential for real-time pattern recognition and photoconfiguration of artificial neural networks (ANN) in a wide spectral range of sensitivity provided by polarized light.     

流固耦合作用下真实人体上呼吸道呼吸流涡结构演化的数值仿真

通过构建真实人体上呼吸道三维规范模型,运用大涡模拟数值方法,对考虑流固耦合作用的低强度循环呼吸模式下人体上呼吸道内的呼吸流进行了数值仿真,研究分析了人体口喉模型及气管支气管内的气流涡结构及其演化过程。结果表明,循环吸气过程中,气流在口腔中部以及舌苔上部形成多个涡管,在声门部位形成强烈的射流,在气管前壁出现马蹄涡,到气管中部大尺度涡结构逐步消失,支气管中只剩下一系列小尺度涡结构;循环呼气过程中,气流在气管底部产生较为复杂的涡结构,随着气流在气管内的融合,涡强度逐步减弱,在咽喉后壁形成拱状涡,气流进入口腔后,涡结构破裂,涡量扩散,没有较大的涡结构产生。     

酸水解法快速测定肉和肉制品中脂肪

建立酸水解法快速测定富含结合态脂肪的肉及肉制品中脂肪含量的方法。样品与盐酸一同在75℃水浴中加热进行水解，结合或包藏在组织里的脂肪可游离出来，然后用乙醚和石油醚提取3次，除去溶剂即得样品中总脂肪含量。该方法测定结果同食品安全国家标准GB 5009.6—2016规定方法相比无显著差异，测定结果的相对标准偏差为0.38%(n=20)，测定时间由食品安全国家标准GB 5009.6—2016方法的13 h缩短至4 h，且不需要专门的索氏抽提仪器。该方法适用于肉及肉制品中脂肪的批量测定。