高效液相色谱法同时测定婴幼儿配方乳粉中5种游离核苷酸

建立了婴幼儿配方乳粉中5种游离核苷酸的准确测定方法。采用等电点沉淀蛋白,强阴离子交换固相萃取柱净化,Atlantis T3色谱柱分离,二极管阵列检测器检测,外标法定量。结果表明:5种核苷酸在0.1~100μg/m L范围内线性关系良好(r≥0.999),平均回收率为95.2%~103%,相对标准偏差均小于4.5%。方法可为企业质量控制和政府监管提供有力的技术支撑。     

The Panel Method for Rigid Section Group Added Mass Coefficients and Its Application to Fuel Assemblies北大核心CSCD

A numerical method based on the panel method was developed to calculate the added fluid mass coefficients of the rigid section group with arbitrarily complex shapes, and was successfully applied to the PWR fuel assemblies. The variation law of added mass coefficients with position deviations was analyzed in the seismic test of 1×5 fuel assemblies. The results show that, this method is suitable for the calculation of the added mass coefficients of rigid section groups with complex continuous boundaries. Compared with the gap between assemblies, the gap between baffles and assemblies has a dominant influence on the added mass coefficient. Regardless of the position deviation, the sum of the added mass coefficients of all assemblies and baffles in the assumed motion direction is approximately equal to –1, and that in the perpendicular direction is approximately equal to 0. © 2023 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

Dissection of the Zipping-and-Assembly Mechanism for Folding of Model Proteins

Zipping-and-assembly mechanism （ZAM） is a new mechanism describing the kinetics of protein folding. To dissect the validity of this mechanism for various protein-like systems, a prediction test based on three-dimensional HP lattice models is carried out. It is found that only the native structures of a part of protein-like models could be predicted with a ZAM-based method. The detailed comparisons between the model proteins which are predicted or failed with the ZAM-based method suggest that the ZAM is likely to be applicable for the model proteins with the weak hydrophobicity, the low contact order for native conformations, and the large separation between the energies of native state and denatured states. These observations bring us more information about the protein-like systems for which the ZAM could be applied.     

反相离子对色谱法测定化妆品中溴硝丙醇等11种防腐剂

采用反相离子对色谱法测定化妆品中溴硝丙醇等１１种防腐剂,以ＺｏｒｂａｘＣ８为固定相,Ｖ（０．０５ｍｏｌ／Ｌ磷酸二氢钠）∶Ｖ（甲醇）∶Ｖ（乙腈）＝５０∶３５∶１５的溶液为流动相,添加氯化十六烷三甲胺（浓度为２ｍｍｏｌ／Ｌ）,用磷酸调ｐＨ值为３５,检测波长为２５４ｎｍ。样品用甲醇超声提取,回收率为８５％～１０７％（ｎ＝６）,相对标准偏差为２２％～７．５％。     

基于壳聚糖的新型敷料及其应用

壳聚糖由于具有凝血、抗菌、生物相容性好、可生物降解等优点,在材料学和生物医药等领域表现出巨大的应用潜力。本文介绍了壳聚糖的凝血、抑菌机理,列举了基于壳聚糖的新型敷料的研究进展。按照形态的不同将其分为基于壳聚糖的织物类敷料、基于壳聚糖的水凝胶敷料、基于壳聚糖的海绵状敷料、基于壳聚糖的水胶体敷料、基于壳聚糖的不对称湿润性敷料和基于壳聚糖的冷冻凝胶敷料;总结了基于壳聚糖的新型敷料在抑菌性质、体外凝血性质、防水性质、透气性质和力学性质等方面的实验结果;详细归纳了基于壳聚糖的新型敷料在治疗糖尿病足溃疡、烧伤创面、下腔静脉损伤和内窥镜鼻窦手术等疾病方面的应用。最后,对基于壳聚糖的新型敷料存在的一些问题(如制备过程受外界环境的条件的影响较大、对壳聚糖的部分工作机理还处于初步阶段)和发展做出了展望。     

高效液相色谱法测定淀粉及相关食品中马来酸(酐)与富马酸的含量

建立了高效液相色谱法测定淀粉及相关食品中马来酸(酐)和富马酸的分析方法。试样采用1%氨水-甲醇(体积比1∶1)溶液提取,以0.03 mol/L磷酸二氢铵(pH 2.45)溶液为流动相,采用AtlantisT3 C18色谱柱进行分离,二极管阵列检测器检测。结果表明,在优化色谱条件下,两种目标物的分离良好,回收率为82.5%~103.5%,相对标准偏差小于4.3%,两者的定量下限均为2.0 mg/kg。该方法前处理简便快捷、灵敏度高、回收率和重现性良好,适用于淀粉及相关食品中马来酸(酐)及富马酸的测定。     

Bézier曲面在三角域和矩形域上的互化

Bezier曲面是CAD/CAM中应用最为广泛的曲面之一。它可分为两类:矩形域上张量积形式的Bezier曲面:三角域上的Bezier曲面:     

Protein Folding in Nano-Sized Cylinders

The folding of a model protein confined in a nano-sized cylinder is studied by the off-lattice Go^-like model. The entropy and anisotropy effects of confinement on thermodynamics and dynamics for folding are investigated. Our results show that due to reduction of the search on conformations, the folding rate can be sped up and the thermodynamic stability is enhanced at the cost of the decrease of folding cooperativity. In addition, it is found that these are shape-dependent. Folding is optimized in a cylinder with an appropriate shape when the volume is fixed. This is probably related to the shape of the protein molecule. Furthermore, our results also suggest that there is an orientational transition for the protein molecule following the variation of the radius of cylinder.     

低能区强耦合常数的测量

强耦合常数,α_s(s)是量子色动力学最重要的参数. 基于BES的R值测量结果, 分别利用精确到3圈和4圈的微扰QCD的计算, 测定了α_s(s)在2.0—3.7GeV能量范围的数值, 并推断了α_s(s)演化到Z⁰能标下的值α_s(M_z). 同时对在未来实验中R值测量精度的提高对α_s(s)的不确定性的减小作了定量的预言.     

超高效液相色谱-串联质谱法测定化妆品中的腈菌唑

建立了超高效液相色谱-串联质谱法测定化妆品中腈菌唑的方法。试样经乙腈提取,正己烷萃取除去脂溶性杂质,氮气吹干富集,采用UPLC-MS/MS,以C18色谱柱分离,电喷雾电离(ESI),正离子,多反应监测(MRM)模式检测,外标法定量。在1~100 ng·mL-1范围内,线性相关系数0.99;添加回收率范围82.4~91.5%,相对标准偏差(RSD)4.8%~9.5%,方法定量下限0.5μg·kg-1。该方法快速、检测灵敏度高,可适用于各类化妆品中腈菌唑的测定。