CONFORMATION AND CHAIN PACKING STRUCTURES OF POLY (ρ-PHENYLEN BENZOBISTHIAZOLE) BY MOLECULAR SIMULATION*

The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chaincould even be stabilized in various values. It therefore indicates that the intermolecularinteraction does play a considerable role for this polymer forming the conformation. Ac-cording to cohesive energies calculated for these unit cell models, the torsion angle in themost stable crystalline cell is 0°. When the chains packing together, there exist so manyenergy stable wells along the chain axis 0.35--0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies. These factors thus cause thedifficulty of forming an unique perfect crystalline structure of the polymer. The presentstudy suggested a number of reasonable unit cells, and the most stable crystalline structurefor this polymer that is monoclinic, non-primitive unit cell.     

Ni[(C6H11O)2PS2]2与氮碱加合反应的研究

用光谱法研究了Ni[(C_6H_(11)O)_2PS_2]_2与咪唑,4-甲基吡啶,2,4-二甲基吡啶,2,2＇-联吡啶,乙胺,正丙胺,正丁胺和二乙胺的加合反应,测定了加合反应的平衡常数。平衡常数随着氮碱分子碱度增加而增大,随着氮碱分子空间位阻的增加而减小。讨论了几类氮碱加合反应平衡常数测定的处理方法。     

Analysis of intracellular reactive oxygen species by micellar electrokinetic capillary chromatography with laser-induced-fluorescence detector

Reactive Oxygen Species (ROS) are an important part of the normal cell growth cycle and play essential roles in many biological functions. Many techniques have been developed to detect and measure the amount of ROS present in cells. These techniques include spectrophotometry, high performance liquid chromatography (HPLC), capillary electrophoresis with laser-induced-fluorescence detector (CE-LIF) and capillary electrophoresis-on-a-chip with LIF. As ROS has a short half-life outside of the cell, various fluorescent probes, such as dihydrorhodamine 123 (DHR 123), that are membrane permeable have been used in the detection of intracellular ROS. In this paper, micellar electrokinetic capillary chromatography (MEKC) was coupled with LIF detector. Fluorescent probe, 3′-(p-aminophenyl)-fluorescein (APF), was used to detect specific ROS in Chinese Hamster Ovary (CHO) suspension cells as well as attached mouse bone marrow-derived dendritic cells (BMDCs). Separation buffer composition was optimized at a concentration of 25?mM tetraborate buffer with 50?mM sodium dodecyl sulfate at pH 9.3 and lysis of the cells was done successfully with a buffer of 70% ethanol and 0.1mM sodium dodecyl sulfate using a cell amount of 1?×?10⁷. ROS in cells was successfully analyzed by MEKC-LIF method developed, with acceptable RSD for time at 1.54% and area at 2.81%.     

Full-Wave Analyses for Vertical Interconnections of Shielded Coplanar Waveguide

Three dimensional (3D) interconnection plays important role in modern millimeter wave integrated circuit (MMIC). In this paper, vertical interconnections of shielded coplanar waveguides, which appear typically in multichip module MMICs, are analyzed through the full-wave finite-difference time-domain (FDTD) method.     

Theoretical investigation on transformation of Cr(II) to Cr(V) complexes bearing tetra-N-heterocyclic carbene and group transfer reactivity

The mechanism for the transformation among a series of Cr(II) to Cr(V) complexes bearing tetra-N-heterocyclic carbene macrocycle is investigated. The oxidation and aziridination of Cr(II) monomer are studied by local density functional M06L. The former generates Cr(IV) oxo and further oxidizes to cationic Cr(V) oxo. The latter proceeds via two paths with different multiplicity, forming Cr(IV) imide. The Cr(IV) oxo cannot transfer its oxygen atom neither to phosphine nor to alkene because of the high energy barrier and endothermic process. The group transfer reactions are explored for Cr(V) oxo and Cr(IV) imide. The doublet Cr(V) oxo can also exist as quartet Cr(IV)-oxyl radical and promote oxygen transfer to phosphine, resulting in phosphine oxide in one exergonic step. The macrocyclic ligand effect of imido group transfer from Cr(IV) imide is verified by Multiwfn analysis. For 18-ringed imide, the matched orbital type and same-phase overlap reduce the barrier of its 16-ringed analog and facilitate the formation of phosphorus imine.