CNDO Studies on the Intermolecular Coulomb Interaction in TCNQ-Stack

The coulomb interaction among TCNQ- molecules in different stack structures was calculated by quantum chemistry CNDO method. The results of the calculation would be used to explain the change rule of the electricity property of the TCNQ complex very well.     

Evaluation of one-centre electron interaction integrals over slater type atomic orbitals

Simplified expressions for one-centre electron interaction integrals in general and Slater-Condon parameters as well as repulsion integrals of the type (aa|aa) in particular have been obtained over Slater-type atomic orbitals. Results calculated using these expressions are in agreement with those due to other authors.     

Miscibility of polycarbonates with copolymers containing cyclohexylmethacrylate

We prepared various copolymers containing styrene and methacrylates to examine their miscibility with polycarbonates such as bisphenol A polycarbonate (PC), dimethylpolycarbonate (DMPC), and tetramethylpolycarbonate (TMPC). Among the various copolymers examined, poly(methyl methacrylate‐co‐cyclohexylmethacrylate) [P(MMA–CHMA)] copolymers containing proper amounts of cyclohexylmethacrylate (CHMA) formed miscible blends with PC and DMPC, whereas TMPC did not form a miscible blend with P(MMA–CHMA). However, TMPC was miscible with poly(styrene‐co‐cyclohexylmethacrylate) [P(S–CHMA)] copolymers containing less than about 40 wt % CHMA, whereas PC and DMPC were always immiscible with P(S–CHMA). Miscible blends exhibited lower critical solution temperature (LCST)‐type phase behavior. Binary interaction energies were calculated from the observed phase boundaries with lattice–fluid theory combined with a binary interaction model. The quantitative interaction energy of each binary pair indicated that the phenyl ring substitution of polycarbonate with methyl groups did not lead to interactions that were favorable for miscibility with methyl methacrylate (MMA) and CHMA, but it did lead to favorable interactions with styrene. The addition of CHMA to MMA initially increased the LCST but ultimately led to immiscibility with PC and DMPC; however, addition of CHMA to styrene always decreased the LCST with TMPC. The increased LCST of PC or DMPC blends stemmed from intramolecular repulsion between MMA and CHMA, whereas the decreased LCST of TMPC/P(S–CHMA) blends with CHMA content came from negative interaction energy between styrene and CHMA. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1948–1955, 2001     

Properties of mixed protein/surfactant adsorption layers

The adsorption isotherms, adsorption kinetics and surface rheological properties of β-lactoglobulin, β-casein, in the absence and presence of Tween 20 were measured. To study the adsorption process (isotherms and kinetics) at the water–air interface the pendant drop technique (axial drop shape analysis, ADSA), and ring tensiometry were used. The surface shear rheological parameters were measured with a torsion pendulum set-up. Also, data of the equilibrium film thickness and surface diffusion coefficients obtained from fluorescence recovery after photobleaching (FRAP) measurements are used to understand the competitive adsorption mechanism. The adsorption process and shear rheological behaviour of the studied systems show a rather complex behaviour which depends most of all on the system's composition. At high protein or surfactant content the behaviour is controlled by the main component while for the more mixed systems the adsorption process is complex and consists of partial adsorption, surfactant–protein interaction and protein rearrangement as a function of surface coverage. The results obtained illustrate that all these processes must be taken into account in future new theoretical models to be derived for such systems.     

Ligand–macromolecule complexes: affinity index determination by selective nuclear relaxation analysis

Proton NMR selective and non-selective spin–lattice relaxation rate measurements were used to monitor the strength of the overall complexation behaviour of a ligand (carbamazepine) toward a macromolecular receptor (albumin). The ‘affinity index,’ a quantitative parameter related to the strength of the ligand–macromolecule interaction, was determined from the experimental contribution of the bound ligand molar fraction to the observed selective spin–lattice relaxation rate. The effect of a second ligand (lamotrigine) on the carbamazepine–albumin interaction was also investigated and was found to have a modulation effect on the carbamazepine–albumin interaction. Copyright © 2001 John Wiley & Sons, Ltd.     

Calculation of QED Effects in Hydrogen

Atomic mass differences are influenced by QED corrections, and a reliable understanding of these corrections is therefore of importance for the current and next generation of high-precision mass determinations based on Penning traps. We present a numerical evaluation of the self-energy correction, which is the dominant contribution to the Lamb shift, in the region of low nuclear charge. Our calculation is nonperturbative in the binding field and has a numerical uncertainty of 0.8Hz in atomic hydrogen for the ground state and of 1.0Hz for L-shell states (2S_1/2, 2P_1/2, and 2P_3/2). This revised version was published online in July 2006 with corrections to the Cover Date.     

Gas-solid interaction force from direct numerical simulation (DNS) of binary systems with extreme diameter ratios

nding the large particles becomes less in case ofa bidisperse mixture, as compared to a monodisperse system with the same volume fraction. We further investigated this discrepancy by calculating the volume per particle by means of Voronoi tessellation.     

Chromatographic Processing Scheme for Continuous Harvesting of rec-Prourokinase from Serum Free Medium Cell Cultures

Continuous perfusion cell culture, using albumin containing medium, offers the potential advantages of higher recombinant Prourokinase (r-ProUK) yields, higher initial product purity and increased throughput compared to batch culture technology using medium supplemented with fetal bovine serum. We have characterized the production of r-ProUK in medium supplemented with a lipid rich bovine serum albumin (Albumax) in a perfusion system. The results of these studies showed that it was necessary to modify the r-ProUK batch recovery scheme to process r-ProUK from a perfusion system. To accommodate large volumes of perfusate harvested over a ten to fourteen day production cycle, cation exchange and hydrophobic interaction chromatography (HIC) resins were identified that had increased product binding capacity, better flow characteristics and wider pH ranges which allowed caustic cleaning. The mobile phase composition, pH and ionic strength were modified to improve r-ProUK yields from the identified resins, and procedures were developed to eliminate r-ProUK degradation products. Strategies were defined for processing continuous harvest, which contained four to seven times the amount of r-ProUK of batch harvests.     

DNA水凝胶在生物传感中的应用和发展

脱氧核糖核酸(DNA)是一种重要的生物分子,具有许多独特的性质如:信息传递、分子识别、可编辑等。DNA水凝胶同时具有DNA分子和水凝胶材料的优势,并且可以引入其他纳米材料获得多功能杂化水凝胶。相比于传统水凝胶,DNA水凝胶具有良好的特异识别能力以及可以按需设计的性质,从而被广泛应用于生物传感领域。本文围绕DNA水凝胶的合成、响应机制以及在传感领域的应用进行综述。按照不同的合成方法可分为线性DNA链缠绕水凝胶、枝状DNA自组装水凝胶、杂合DNA水凝胶。根据传感机制的不同又可以分为包埋封装法和非包埋封装法,包埋封装发法又分为:酶的包埋释放、抗原-抗体的包埋释放、纳米材料的包埋释放。本文总结了近几年DNA水凝胶在重金属离子检测、核酸检测、葡萄糖检测、蛋白质和代谢小分子检测,以及细胞检测等热门领域的研究情况,最后对其未来的发展进行了展望。