This study evaluated the inhibitory effects of thiazolidine derivatives on hepatitis C virus (HCV) protease and other human serine proteases. The inhibition efficacy was tested with a reversed-phase high-performance liquid chromatography (HPLC) assay system using a NS3-NS4A fusion protein as the HCV protease and a synthetic peptide substrate that mimics the NS5A-5B junction. Nine thiazolidine derivatives showed more than 50% inhibition at 50 microg/ml. The most potent derivative was RD4-6250, with 50% inhibition at a concentration of 2.3 microg/ml; this concentration was lower than those of other protease inhibitors reported previously. The most selective derivative was RD4-6205, with 50% inhibition at a concentration of 6.4 microg/ml, a lower concentration than those on other serine proteases (chymotrypsin, trypsin, plasmin, and elastase). These results suggest that the RD4-6205 skeleton is an important structure for inhibitory activity on the HCV protease NS3-NS4A. 相似文献
The effect of mixing time on hardness, disintegration time and ejection force in tablettlng of magnesium stearate and lactose granules was studied. The hardness of the tablets decreased with an increase in mixing time of the blends, as previously reported. A semilogarithmic plot of the hardness versus mixing time gave a straight line having a turning point. At the early phase of mixing the hardness was decreasing with a large first-order rate and then continued to decrease with another small first-order rate. The change in disintegration time or ejection force versus mixing time was basically the same as that in the hardness. This type of plot was applicable to the mixing magnesium stearate with not only granular but also powdered materials. 相似文献
Single-crystal alumina was implanted firstly with 400 keV Si+ and subsequently with N2+ ions and then annealed at 1673 K in an No atmosphre. The implanted layers were characterized by means of X-ray diffraction, Rutherford backscattering-channelling of 2 MeV He+ ions, and the resonance nuclear reaction15N(p,)12C. The annealing of sapphire implanted at ambient temperature resulted in the formation of-sialon, a solid solution of-silicon nitride and alumina in the subsurface layer, while implantation at 100 K resulted in the formation of aluminium oxynitride in the surface layer. In the latter case, the implanted silicon atoms were believed not to react vxi1h the implanted nitrogen atoms but with the substrate oxygen atoms. These crystalline precipitates were found to have epitaxial relations with the sapphire substrate. 相似文献
Powder compacts of synthetic mica (fluorphlogopite) encapsulated in a boro–silicate glass tube were isostatically hot–pressed in a Roy–Tuttle–type pressure vessel. Synthetic mica was sintered to a density of 2.60 g/cm3 (91.2% of theoretical density) without additives under 98 MPa of water at 800°C for 45 min. 相似文献
To improve the performance of air electrodes, the dependence of iron phthalocyanine (FePc) catalytic effects on preparation methods was examined. The methods used were mixture (Electrode 1), impregnation (Electrode 2) and direct synthesis (Electrode 3). Electrodes 2 and 3 showed higher potentials during cathodic polarization up to 10 mA cm–2 than Electrode 1. The rate of chemical destruction of H2O2 decreased in the order Electrode 3 > Electrode 2 > Electrode 1. Electrode 3 showed the smallest potential drop for a discharge at 10 mA cm–2, 0.09 V after 50 h. However, the potential of Electrode 2 decreased with discharge, becoming 0.09 V lower than that of Electrode 3 after a 50 h discharge at 10mA cm–2. Once the potential drop occurred, the potential was not recovered by resting or by drying the electrode. The potential drop may be caused by deactivation of FePc. One possible reason for such deactivation is the presence of H2SO4, which remained on the electrode after impregnation of the FePc-H2SO4 solution. 相似文献
This paper presents a quasi-static multiscale computational model with its verification and rational applications to mechanical behavior predictions of asphaltic roadways that are subject to viscoelastic deformation and fracture damage. The multiscale model is based on continuum thermo-mechanics and is implemented using a finite element formulation. Two length scales (global and local) are two-way coupled in the model framework by linking a homogenized global scale to a heterogeneous local scale representative volume element. With the unique multiscaling and the use of the finite element technique, it is possible to take into account the effect of material heterogeneity, viscoelasticity, and anisotropic damage accumulation in the small scale on the overall performance of larger scale structures. Along with the theoretical model formulation, two example problems are shown: one to verify the model and its computational benefits through comparisons with analytical solutions and single-scale simulation results, and the other to demonstrate the applicability of the approach to model general roadway structures where material viscoelasticity and cohesive zone fracture are involved. 相似文献