气相色谱法测定橡皮擦中甲醛时衍生参数的影响分析

利用甲醛与2,4-二硝基苯肼的衍生反应,用气相色谱法测定橡皮擦中的甲醛时对衍生参数的影响进行分析。对关键衍生环节中的衍生因素如衍生剂用量、衍生温度、衍生时间、提取剂等进行试验,确定衍生剂用量为0.5mL,衍生温度为70℃,衍生时间15 min;提取剂为甲苯,用量为每次5 mL,充分振摇1 min,提取2次。橡皮擦中甲醛的质量浓度在0.105~10.5 mg/L范围内与色谱峰面积呈良好的线性,线性相关系数r=0.999 7,测定结果的相对标准偏差为2.1%(n=6),检出限为0.01 mg/L,平均加标回收率为88.4%。该衍生气相色谱法灵敏度高,稳定性好,可用于橡皮擦产品中甲醛的快速检测。     

A scoring function for docking ligands to low-resolution protein structures

We present a docking method that uses a scoring function for protein-ligand docking that is designed to maximize the docking success rate for low-resolution protein structures. We find that the resulting scoring function parameters are very different depending on whether they were optimized for high- or low-resolution protein structures. We show that this docking method can be successfully applied to predict the ligand-binding site of low-resolution structures. For a set of 25 protein-ligand complexes, in 76% of the cases, more than 50% of ligand-contacting residues are correctly predicted (using receptor crystal structures where the binding site is unspecified). Using decoys of the receptor structures having a 4 A RMSD from the native structure, for the same set of complexes, in 72% of the cases, we obtain at least one correctly predicted ligand-contacting residue. Furthermore, using an 81-protein-ligand set described by Jain, in 76 (93.8%) cases, the algorithm correctly predicts more than 50% of the ligand-contacting residues when native protein structures are used. Using 3 A RMSD from native decoys, in all but two cases (97.5%), the algorithm predicts at least one ligand-binding residue correctly. Finally, compared to the previously published Dolores method, for 298 protein-ligand pairs, the number of cases in which at least half of the specific contacts are correctly predicted is more than four times greater.     

Can Quantum Correlations Lead to Violation of the Second Law of Thermodynamics?

Quantum entanglement can cause the efficiency of a heat engine to be greater than the efficiency of the Carnot cycle. However, this does not mean a violation of the second law of thermodynamics, since there is no local equilibrium for pure quantum states, and, in the absence of local equilibrium, thermodynamics cannot be formulated correctly. Von Neumann entropy is not a thermodynamic quantity, although it can characterize the ordering of a system. In the case of the entanglement of the particles of the system with the environment, the concept of an isolated system should be refined. In any case, quantum correlations cannot lead to a violation of the second law of thermodynamics in any of its formulations. This article is devoted to a technical discussion of the expected results on the role of quantum entanglement in thermodynamics.     

高压静电吸附除尘新型板擦的研制

利用高压静电对粉尘有良好絮凝、吸附作用的特点,首先设计静电除尘的模拟吸附装置进行了粉尘吸附的实验,然后设计并组装了具有能够降低小粒径粉尘密度、吸附收集粉尘、防止扬尘等特点的静电吸附除尘新型板擦。