Harmonic oscillator tensors. III: Efficient algorithms for evaluating matrix elements of vibrational operators

Succinct expressions for the matrix elements of various vibrational operators have been derived in the basis of the nondegenerate harmonic oscillator. Among these are the matrix elements of and , which are found to be dependent upon two quantities and their derivatives. Furthermore, the derivative property of the commutator is used to obtain an explicit expression for the derivatives of an operator in terms of its nested commutator with the conjugate momentum. It may be applied to any of the above cases to obtain the matrix representatives of expressions such as the mixed products , for example. In addition, a simple expression for 1/q is given and its derivatives may be evaluated by this commutator technique. Also the matrix elements of a Gaussian-type operator has been evaluated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Charm production and parton distributions

Recent accurate data on F ₂(x,Q) and on F ₂ ^c (x,Q) from HERA at small-x require a more precise treatment of charm production in the global analysis of parton distributions. We improve on existing global QCD analyses by implementing the leptoproduction formalism of Aivazis et al. which represents a natural generalization of the conventional zero mass QCD parton framework to include heavy quark mass effects. We also perform analyses based on the fixed-flavor-number scheme, which is widely used in the literature, and demonstrate their uses and limitations. We discuss the implications of the improved treatment of heavy quark mass effect in practical applications of PQCD and compare our results with recent related works.     

Measurement of the decay rate and the parameter αK* of the decay KL → μμγ

The rate of the decay of the neutral K meson into K _L ⁰ → μμγ has been measured with the NA48 detector at the CERN SPS. A total of 59 events has been observed with an estimated background of 14 events. The overall Kaon flux was determined to be 1.2 × 10⁹. This observation corresponds to a branching ratio of (3.4 ± 0.6_stat ± 0.4_sys × 10^-7. Using this branching ratio the parameter α_K* describing the relative strength of the two contributing amplitudes to this decay, through intermediate pseudoscalar or vectorlike mesons, was measured to be α_K* = -0.04+ _-0.21 ^+0.24 .     

凝血酶抑制剂的结构与活性的关系

应用了一种新的预测酶－配体复合物亲和性的方法来研究凝血酶抑制剂的结构－活性关系．凝血酶－抑制剂复合物的三维结构根据模板化合物的晶体结构进行搭建，然后使用程序SCORE计算复合物的亲和性．共分析了3个系列34个抑制剂分子．计算所得的复合物的解离常数与实验值吻合得很好，大大优于用分子力学所给出的结果．通过比较其中两个抑制剂分子的结构和活性，说明了此方法能够定量给出配体分子中每个原子对结合过程的贡献大小，给出十分直接的结构－活性关系．     

Derivatization,Separation and Determination of Steroids and Triterpenoids by Reverse-Phase HPLC and UV Detection

The steroids were derivatised with aroyl chloride to yield the corresponding benzoates. Among them, their 4-methoxybenzoates were obtained in greatest yield and were analyzed by HPLC with the smallest detection limit (10 ng) by means of a UV detector (254 nm). This method of derivatization can be applied for analysis of steroids and triterpenoids from crude products with the HPLC technique.     

Analytical magnetapheresis of magnetically susceptible particles

Analytical magnetapheresis is a newly developed technique for analyzing magnetic particles. The magnetically susceptible particles form deposition patterns after flowing through a separation channel in a magnetic field. The separation channel requirements for analytical magnetapheresis are an excellent seal for the carrier flow and ease of disassembly after magnetapheresis. Previously used separation channels often exhibit variable channel leakage and unstable flow velocities. We improved the separation channel assembly to ensure stable, high flow velocities and characterized the system with various magnetically susceptible and labeled particles. Our new separation channel featured silicone sealant with embedded nylon wires and met analytical magnetapheresis requirements. Characterization of this system was performed using several magnetically susceptible particles, and we studied a variety of diamagnetic sample labels with paramagnetic ions and magnetically susceptible particles at different flow-rates and solution pH values. The minimal labeling concentration for complete deposition was determined to be approximately 2.50 x 10(10) ions per particle for test samples at a flow velocity of 0.67 mm s(-1) and a magnetic field gradient of 2.8 T mm(-1). Silicas, yeasts and blood cells were used for these studies. We determined that the minimal difference in magnetic susceptibility (delta(chi)) for successful separation was approximately 2.00 x 10(-6) [SI]. The magnetic susceptibilities of Dynabeads M-450 at several separation distances and flow-rates were determined to be 0.25 [SI], within 2% of values published by other workers. The magnetic susceptibilities of various ion-labeled yeasts and cells were determined and most varied by less than 5% at different flow-rates. The results of this study provide very important references for analytical magnetapheresis applications.     

Theoretical study on the reaction mechanism and thermodynamics of tin oxidation by oxygen species and chlorine species

In this work ab initio molecular orbital methods were employed to study the coal combustion reaction mechanisms of tin oxidized by different oxidants, including HOCl, HCl, ClO, ClO₂, NO₃, CO₂, and O₂. Eleven reaction pathways were identified. The results show that Sn can react with HCl, ClOO, CO₂, O₂, and NO₃ to form SnO and SnCl. SnO can be oxidized into SnCl by HOCl and HCl. SnCl can be further oxidized into a soluble compound, SnCl₂. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Palladium catalyzed Suzuki coupling reactions using cobalt-containing bulky phosphine ligands

Three bulky mono-dentate alkyne-bridged dicobalt-phosphine complexes [(μ-PPh₂CH₂PPh₂)Co₂(CO)₄](μ,η-PhCCPPh₂) 4a, [(μ-PPh₂CH₂PPh₂)Co₂(CO)₄](μ,η-Me₃CCCPPh₂) 5a and [(μ-PPh₂CH₂PPh₂)Co₂(CO)₄](μ,η-Me₃SiCCPPh₂) 6a were prepared from the reactions of the bis(diphenylphosphino)methylene (dppm) bridged dicobalt complex Co₂(CO)₆(μ-Ph₂PCH₂PPh₂) with PhCCPPh₂1, Me₃CCCPPh₂2, and Me₃SiCCPPh₂3, respectively. These three metal-containing compounds 4a, 5a and 6a were employed as ligands, replacing conventional organic phosphines, in the Suzuki cross-coupling reactions and have been proved to be effective, authentic mono-dentate phosphine ligands.