Indirect Methods For Determination of The Protective Effects of Coating Films on The Surface of Crystals

The extents of the protective effects of coating films on the surface of crystals were determined. Three different samples were made with different quantities of coating fluid (Sepifilm LP 010 in 10% aqueous solution). Since the atomizing rate was constant, the coating time increased in parallel with the volume of coating fluid applied. The direct measurement of film thickness and smoothness is very difficult, and therefore indirect methods were used. Dimenhydrinate was chosen as model drug; this is a heat-sensitive antihistamine with a low melting point. This temperature can be reached during the tableting process. The behaviour of samples on exposure to heat was examined by differential scanning calorimetry. The water uptakes of the samples were determined with an Enslin apparatus. Plasticity was studied with an instrumented tablet machine. These indirect methods (thermal conductivity, water uptake and plasticity measurements) revealed connections between the results of the various experiments. An overlong coating time decreased the protective effect of the coating film. This revised version was published online in August 2006 with corrections to the Cover Date.     

Enhancing the Bolzon–Schrefler–Zienkiewicz Constitutive Model for Partially Saturated Soil

This paper presents an enhanced version of the elasto-plastic model for partially saturated soil first proposed by Bolzon, Schrefler and Zienkiewicz in 1996, “BSZ” model, which uses the effective stress tensor and suction as independent stress variables. It is recalled that the effective stress tensor proposed by Lewis and Schrefler in 1982 is thermodynamically consistent and, compared with other choices of stress tensors, results particularly suitable for partially saturated soil mechanics. A hydraulic constitutive relationship and a hydraulic hysteresis are introduced in the model, to take into account the irreversible deformation during cyclic drying and wetting until structural collapse. For this reason the plastic rate of strain is split into the sum of two components: one depending on the effective stress tensor and the other one on suction. This is the new feature of the BSZ model. This enhanced model is then cast into a thermodynamical framework at macroscopic level and it is shown that it is possible to derive the constitutive law from the Helmholtz free energy and a dissipation function, both for associative and non- associative plasticity. Finally the model predictions have been compared with experimental data for Sion slime, with particular emphasis on the deviatoric part, and model predictions of hysteretic behaviour have been investigated in case of a wetting and drying cycle on compacted betonite–kaolin.     

光照和氮素对外来植物凤眼莲生长和生理特性的影响

通过研究不同光照和氮素营养处理的外来植物凤眼莲的生长、生物量分配、硝酸还原酶活性、游离氨基酸以及可溶性蛋白质含量变化，探讨其对环境适应性的生理学机制。凤眼莲表现出极强的可塑性，随光照和氮素营养的增加，凤眼莲生长速率明显加快，氮素代谢关键酶硝酸还原酶活性上升。根部吸收的硝酸根离子大部分运输到叶片中还原，氮素同化效率高。氨基酸含量和可溶性蛋白质含量呈现明显的变化，叶片可溶性蛋白质含量与根冠生物量分配显著相关。本研究表明风眼莲对光照和氮素表现出很强的适应性，其快速生长和高可塑性依赖于对环境变化的牛理响廊。     

Escape Through a Small Opening: Receptor Trafficking in a Synaptic Membrane

We model the motion of a receptor on the membrane surface of a synapse as free Brownian motion in a planar domain with intermittent trappings in and escapes out of corrals with narrow openings. We compute the mean confinement time of the Brownian particle in the asymptotic limit of a narrow opening and calculate the probability to exit through a given small opening, when the boundary contains more than one. Using this approach, it is possible to describe the Brownian motion of a random particle in an environment containing domains with small openings by a coarse grained diffusion process. We use the results to estimate the confinement time as a function of the parameters and also the time it takes for a diffusing receptor to be anchored at its final destination on the postsynaptic membrane, after it is inserted in the membrane. This approach provides a framework for the theoretical study of receptor trafficking on membranes. This process underlies synaptic plasticity, which relates to learning and memory. In particular, it is believed that the memory state in the brain is stored primarily in the pattern of synaptic weight values, which are controlled by neuronal activity. At a molecular level, the synaptic weight is determined by the number and properties of protein channels (receptors) on the synapse. The synaptic receptors are trafficked in and out of synapses by a diffusion process. Following their synthesis in the endoplasmic reticulum, receptors are trafficked to their postsynaptic sites on dendrites and axons. In this model the receptors are first inserted into the extrasynaptic plasma membrane and then random walk in and out of corrals through narrow openings on their way to their final destination.     

Al/Al2O3P金属基复合材料的静动态压缩性能及损伤分析

用气压浸渗工艺制备了体积分数40％～50％Al2O3颗粒增强纯铝基复合材料，使用了4种不同尺寸的Al2O3颗粒，其平均粒径分别为5μm、10μm、30μm和60μm．测定了这些复合材料的静、动态压缩性能，并通过材料压缩前后密度变化的测量定量表征了材料的累计损伤，结果表明，与基体材料相似，这些复合材料表现出明显的应变率敏感性；当增强颗粒平均粒径小于60μm时，材料的累计损伤基本与应变率无关，而主要取决于材料的应变．材料中颗粒的破裂主要是由颗粒间的相互作用引起的．较小尺寸颗粒增强的复合材料具有较高的流动应力和较小的累计损伤，并随着颗粒体积分数的增加，材料的流动应力和损伤率都相应增加．     

Synthesis of new 7-aminosterol squalamine analogues with high antimicrobial activities through a stereoselective titanium reductive amination reaction

A series of 7-amino- and polyaminosterol analogues of squalamine and trodusquemine were synthesized involving a new stereoselective titanium reductive amination reaction in high chemical yields of up to 95% in numerous cases. These derivatives were evaluated for their in vitro antimicrobial properties against human pathogens. All the compounds present excellent activities against Gram-positive bacteria exhibiting similar results against Staphylococcus aureus and Streptococcus faecalis with minimum inhibitory concentrations (MICs) varying from 2.5 to 10 μg/mL. Numerous derivatives possess also MICs against Gram-negative Escherichia coli bacteria (MICs varying from 2.5 to 10 μg/mL) suggesting that nature of the amino group attached to the sterol moiety plays an important role on the activities of such products.     

Neosappanone A, a xanthine oxidase (XO) inhibitory dimeric methanodibenzoxocinone with a new carbon skeleton from Caesalpinia sappan

A novel dimeric methanodibenzoxocinone, named neosappanone A (1), possessing a unique unprecedented novel carbon framework, has been isolated from the heartwood of Caesalpinia sappan L. of Vietnam, and its structure was elucidated on the basis of spectroscopic analysis. Neosappanone A (1) competitively inhibited xanthine oxidase in a concentration-dependent manner (IC₅₀, 29.7 μM; K_i, 16.3 μM).     

Antihypertensive Effect of Angiotensin‐Converting Enzyme Inhibitory Peptide Obtained from Hen Ovotransferrin

Angiotensin I‐converting enzyme (ACE) inhibitory peptide was isolated from the hen ovotransferrin hydrolysate using chymotryptic hydrolysis by two steps of reverse‐phase high‐performance liquid chromatography. The amino sequence of this novel peptide was identified as Lys‐Val‐Arg‐Glu‐Gly‐Thr‐Thr‐Tyr that inhibited ACE activity in vitro in a concentration‐dependent manner with an effective concentration (IC₅₀) of 102.8 μM. Also, this inhibition was identified as noncompetitive using the Lineweaver‐Burk plot. Moreover, the antihypertensive action of this novel peptide was investigated by an intravenous injection into spontaneously hypertensive rats (SHR). A dose‐dependent reduction of systolic blood pressure by this peptide was observed after 40 min of treatment and it decreased the blood pressure markedly at the maximal dose (1 nmol/mL/kg). The maximal blood pressure lowering activity of this peptide was calculated as 163% of captopril (10 pmol/mL/kg) that was used as positive control. In conclusion, the obtained data suggests that Lys‐Val‐Arg‐Glu‐Gly‐Thr‐Thr‐Tyr has an ability to inhibit ACE activity and decrease the systolic blood pressure in hypertensive animals.