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This study is the first step in the systematic investigation of substituted (carboxyl) polystyrene nanoparticles. Understanding the fundamental interactions between the p-carboxyl styrene monomers, where an ethyl group is used instead of a vinyl group (referenced, for convenience, as "p-carboxyl styrene"), provides the basic information needed to construct potentials for nanoparticles composed of these monomers. In this work, low-energy isomers of p-carboxyl styrene dimer were studied. The dimer structures and their relative and binding energies were determined using both M?ller-Plesset second-order perturbation theory (MP2) and the general effective fragment potential (EFP2) method. Sections of the intermolecular potential energy surface (PES) of the p-carboxylated styrene dimer in its global minimum orientation were also determined. As expected, double hydrogen bonding between the two carboxylic groups provides the strongest interaction in this system, followed by isomers with a single H-bond and strong benzene ring-benzene ring (pi-pi) type interactions. Generally, the EFP2 method reproduces the MP2 geometries and relative energies with good accuracy, so it appears to be an efficient alternative to the correlated ab initio methods, which are too computationally demanding to be routinely used in the study of the more-complex polymeric systems of interest. 相似文献
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M. S. Jovanović J. Brborić S. Vladimirov B. Zmbova LJ. Vuksanović D. Živanov-Stakić V. Obradović 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):321-324
A new diiodine substituted IDA derivative, 2,4-diiodine-6-methyl IDA (DIIODIDA) was synthesized and labeled with99mTc. It was established that99mTc-DIIODIDA had high radiochemical purity. Biodistribution and influence of bilirubin on99mTc-DIIODIDA biokinetics has been studied in rats and compared to the corresponding results for99mTc-SOLCOIODIDA. Related to99mTc-SOLCOIODIDA,99mTc-DIIODIDA has much better biliary exretion (55.18 versus 43.63%). No change of99mTc-DIIODIDA biokinetics, under influence of bilirubin was noticed. Biliary excretion of99mTc-SOLCOIODIDA has been reduced for about 60%. The protein binding of99mTc-DIIODIDA and99mTc-SOLCOIODIDA were also determined, using in vitro method of precipitation. These results showed that99mTc-DIIODIDA hepatobiliary imaging agent is superior to the presently used99mTc-monoiodine IDA derivatives. 相似文献
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George R. Pack Linda Wong Gene Lamm 《International journal of quantum chemistry》1998,70(6):1177-1184
The energetics of formation of a triple-helical structure in homopurine–homopyrimidine mixtures has been modeled using Poisson–Boltzmann calculations. Oligomers with the sequence d(TC)n and d(AG)n form hydrogen-bonded triple-helical structures of the form d(TC)n⋅d(AG)n⋅d(TC+)n. The third base, a pyrimidine in this case, forms Hoogsteen-type hydrogen bonds with the purine, requiring that the cytosine residues of the third strand protonate at N3. The pKa of cytosine, 4.3 in the isolated solvated molecule, is raised by the strong electrostatic field in the triple helix. We have done calculations of the effective pKa of this cytosine and compared the results with experimental studies of triple-helix formation as a function of pH. This provides a test of various models of the dielectric constant for triplex DNA and its local environment. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1177–1184, 1998 相似文献
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Ohne Zusammenfassung
Correlations between adjacent chalcogen-nitrogen bonds of the intra- and intermolecular type相似文献
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本文获得了有各种相互作用的一般n阶特征量泛函,其耦合系数反映了不同特征量泛函之间的耦合强度.依据定量因果原理,导出了一般n阶特征量泛函的变分原理,获得了一般n阶特征量泛函的Euler-Lagrange方程,它的不同系数可拟合不同的物理现实,如从线性到任意n阶非线性物理系统,使复杂难解的任意n阶非线性物理系统变得具体可解.并获得了该对称变换下不变的m个的守恒量,以及它们之间的关系和统一描述.依据定量因果原理导出了相对性原理,证明了绝对加速参考系、牵连参考系和相对参考系的力都有来自加速度和质量变化的贡献.利用定量因果原理自然导出了广义牛顿第一定律和广义牛顿第二定律,而且还导出了一个新定律,即广义牛顿第三定律,亦即平移不变性系统合力为零定理.进而将研究结论应用于对银河系的修正引力势、分子势、夸克禁闭势等,且其结果与物理实验一致. 相似文献
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Aguilera EF Amador-Valenzuela P Martinez-Quiroz E Lizcano D Rosales P García-Martínez H Gómez-Camacho A Kolata JJ Roberts A Lamm LO Rogachev G Guimarães V Becchetti FD Villano A Ojaruega M Febbraro M Chen Y Jiang H DeYoung PA Peaslee GF Guess C Khadka U Brown J Hinnefeld JD Acosta L Rossi ES Huiza JF Belyaeva TL 《Physical review letters》2011,107(9):092701
Fusion cross sections were measured for the exotic proton-halo nucleus ?B incident on a ??Ni target at several energies near the Coulomb barrier. This is the first experiment to report on the fusion of a proton-halo nucleus. The resulting excitation function shows a striking enhancement with respect to expectations for normal projectiles. Evidence is presented that the sum of the fusion and breakup yields saturates the total reaction cross section. 相似文献
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