Fragment interaction analysis based on local MP2

We have developed a fragment interaction analysis based on local MP2 (FILM) in the context of the fragment molecular orbital (FMO) scheme. The primary purpose of this work is to provide a tool for analyzing inter-fragment interaction associated with dispersion interactions in a large molecule such as protein and DNA. Our implementation of local MP2 (LMP2) is based on the algorithm developed by Pulay and Werner. A potential of FILM was demonstrated using the human immunodeficiency virus type 1 protease (HIV-1 PR) complexed with lopinavir (LPV). The total energy, binding affinity, and inter-fragment interaction energy (IFIE) by the FMO method using LMP2 were compared with those obtained by canonical MP2 and the site-specific information in dispersion interaction was obtained. It turned out that the FILM is a useful tool for analyzing the dispersion interaction between an amino acid residue and a specific site of a ligand.     

聚氧化乙烯和聚醋酸乙烯酯共混热力学参数的理论估算

实验测定了聚氧化乙烯（ＰＥＯ）和聚醋酸乙烯酯（ＰＶＡｃ）的共混热以及共混组分的热压系数和热膨胀系数．并由上述实测值计算了状态方程参数．用Ｈａｍａｄａ~［１－２］等改进的Ｆｌｏｒｙ状态方程理论估算了ＰＥＯ／ＰＶＡｃ混体系的交换能参数（Ｘ_１２）、相互作用参数（ｘ_１２／ｒ_１）和剩余混合体积（Ｖ~Ｅ／Ｖ~０）．     

Randomization tests to identify significant effects in experimental designs for robustness testing

The screening designs applied in robustness tests are usually fractional factorial or Plackett-Burman designs. Different methods to identify significant factor effects estimated from experimental designs for robustness testing are described. In this paper, the use of randomization tests as a statistical interpretation method is examined and compared with both graphical (half-normal probability plot) and statistical methods, such as the estimation of error based on a priori considered negligible effects and the algorithm of Dong. It was found that all statistical methods usually gave similar results, i.e. the same effects are found to be significant. However, sometimes randomization tests indicate either less or more significant factor effects compared to the other methods, regardless the design size. Both randomization tests and the algorithm of Dong become unreliable when about 50% of the examined factors are significant. In such situation, it is advisable to perform an experimental design from which enough negligible effects can be estimated. The graphical interpretation method did not always succeed in indicating the correct number of significant effects.     

研究甲酸在多孔Pt上吸附质的性质以及它与CO的相互作用

应用现场红外反射光谱和微分电化学质谱研究了甲到在多孔Ｐｔ上吸附质的性质。伏安结果显示了甲酸在多孔Ｐｔ上吸附质的氧经与吸附电位和吸附时间有关。在线质谱结果表明从甲酸吸附质氧化成二氧化碳所需要的电子数（ｎｅ）与吸附电位无关。显著地ｎｅ＝２．２说明了甲酸吸附质是由ＣＯ和ＣＯＨ组成，而不是只有单一的ＣＯ或者ＣＯＨ，另一方面，在１２６２ｃｍ＾－１和２０４８ｃｍ＾－１出现的现场红外光谱带证实了甲酸在多孔Ｐｔ上     

黄酮与溶菌酶相互作用的强度衰减-基质辅助激光解吸离子化-质谱研究

建立了黄酮与溶菌酶相互作用研究的强度衰减-基质辅助激光解吸离子化-质谱(Intensity fading matrix-assisted laser desorption/ionization mass spectrometry,IF-MALDI-MS)分析方法.在优化的基质DHB条件下,分别研究了木犀草素、染料木素、芹菜素、槲皮素和大豆黄素与溶菌酶相互作用,比较了溶菌酶加入前后黄酮的相对丰度的变化,并通过竞争实验的方法研究了5种黄酮与溶菌酶结合的亲和性大小.结果表明,5种黄酮与溶菌酶均存在相互作用,亲和性强弱为:木犀草素＞芹菜素,染料木素＞槲皮素＞大豆黄素.结合5种黄酮的结构特征,讨论了黄酮的结构及其与溶菌酶亲和性的关系,发现C5位和C3’位的羟基有利于黄酮与溶菌酶的结合,C3位的羟基不利于黄酮与溶菌酶的结合.本方法具有简便,快速,高效等优点,也可以应用于其它天然产物与蛋白质的相互作用的研究.     

NVH and reliability analyses of the engine with different interaction models between the crankshaft and bearing

The precision of the interaction model is very important to predict NVH and the reliability of an internal combustion engine. The interaction model between the crankshaft and the bearing is hard to be established precisely due to its complex interaction relationship and dynamic characteristic. In this paper, the elasto-hydrodynamic lubrication model with cavitation theory is built to couple with multi-body dynamic theory to analyze the noise and reliability of the engine, the results were compared with nonlinear spring model and hydrodynamic lubrication model based on a typical in-line six cylinder engines, such as load carrying capacity of the bearing, velocity level of the engine surface, noise level of engine surface and stress of the crankshaft. The results showed that the vibration, noise and stress prediction difference is due to the exciting of the oil film pressure distribution, rigid and flexible body that is used to build the dynamic model will lead the load capacity of the bearing to be great different. Nonlinear spring model and hydrodynamic lubrication model are precise enough to predict the vibration or noise. The All the analysis will provide the guidance for the engine NVH optimization and structural reliability design.     

非诺呋他林猝灭BSA荧光的机理研究及分析应用

在pH=7.4的Tris-HCl缓冲溶液中,非诺呋他林对牛血清白蛋白(BSA)的荧光有明显的猝灭作用,据此提出了以BSA为荧光试剂,利用其内源性荧光的变化来测定非诺呋他林的荧光分析新方法。在选定的实验条件下,非诺呋他林浓度在8.0×10-9~2.8×10-7 mol/L范围内与荧光猝灭值△F呈良好的线性关系(相关系数为0.9955),方法检出限为5.4×10-9 mol/L,相对标准偏差为0.86%(c=2.0×10-7 mol/L,n=5)。该方法用于样品中非诺呋他林的测定,结果满意。同时对体系的猝灭机理进行了研究。     

Interactions of Anionic and Neutral Serine with Pure and Metal-doped Graphene Studied by Density Functional Theory

We present a theoretical study of interactions of anionic and neutral serine (Ser) on pure or metal-doped graphene surfaces using density functional theory calculations. Interactions of both types of Ser with the pure graphene surface show weak non-covalent interactions due to the formation of -COOH…π, -COO^-…π, and -OH…π interactions. On metaldoped graphene, covalent interactions to the surface dominate, due to the formation of strong metal-O and O-metal-O interactions. Furthermore, the doped Fe, Cr, Mn, Al, or Ti enhances the ability of graphene to attract both types of Ser by a combination of the adsorption energy, the density of states, the Mulliken atomic charges, and differences of electron density. At the same time, the interaction strengths of anionic Ser on various graphene surfaces are stronger than those of neutral Ser. These results provide useful insights for the rational design and development of graphene-based sensors for the two forms of Ser by introducing appropriate doped atoms. Ti and Fe are suggested to be the best choices among all doped atoms for the anionic Ser and neutral Ser, respectively.     

Effects of metal ion-carbonyl interaction on miscibility and crystallization kinetic of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/lightly ionized PBS

Poly(butylene succinate) (PBS) and PBS-based ionomers (PBSi) with 1.0 and 3.0 mol% sodium sulfonate ionic group were synthesized and blended with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-HHx) via direct melt compounding. FT-IR analysis demonstrated that the sodium metal ion–carbonyl interaction between PHB-HHx and PBS ionomer increased in strength with the ionic group concentration. Both non-isothermal and isothermal analyses showed the crystallization rates of PHB-HHx to decrease as the strength of the sodium metal ion–carbonyl interaction increased. However, the constant value obtained for the Avrami exponent indicated that the presence of PBS ionomer did not interfere in any way with the nucleation mechanism or the geometry of the crystal growth of PHB-HHx. DMTA analysis confirmed that PBS ionomer reduced the crystallinity of PHB-HHx, and this phenomenon increased in proportion to the ionic group content. As the ionic group concentration increased, the sodium metal–carbonyl interaction between PHB-HHx and PBS ionomer became much stronger, resulting in the improvement of the miscibility for the blend. The interaction parameter obtained by analyzing the equilibrium melting temperature was negative for all bend systems, with the ionomer having ionic group content, displaying a more negative value. Based on the Lauritzen–Hoffman secondary nucleation theory, the regime of the PHB-HHx/PBS ionomer blend remained unchanged throughout the crystallization process. In addition, both the nucleation constant and surface free energy were found to decrease as both ionomer content and ionic group concentration increased.