Amphiphilic drug interactions with model cellular membranes are influenced by lipid chain-melting temperature

Small-molecule amphiphilic species such as many drug molecules frequently exhibit low-to-negligible aqueous solubility, and generally have no identified transport proteins assisting their distribution, yet are able to rapidly penetrate significant distances into patient tissue and even cross the blood–brain barrier. Previous work has identified a mechanism of translocation driven by acid-catalysed lipid hydrolysis of biological membranes, a process which is catalysed by the presence of cationic amphiphilic drug molecules. In this study, the interactions of raclopride, a model amphiphilic drug, were investigated with mixtures of biologically relevant lipids across a range of compositions, revealing the influence of the chain-melting temperature of the lipids upon the rate of acyl hydrolysis.     

Production of ethanol from raw juice and thick juice of sugar beet by continuous ethanol fermentation with flocculating yeast strain KF-7

Sugar beet juice can serve as feedstock for ethanol product due to its high content of fermentable sugars and high energy output/input ratio. Batch ethanol fermentation of raw juice and thick juice proved that addition of mineral nutrients could not improve ethanol concentration, but could accelerate the fermentation rate. Fermentation of thick juice with an initial pH of 9.1 did not affect the fermentation process. The continuous ethanol fermentation of raw juice was performed at 35 °C with a dilution rate of 0.3 h⁻¹, resulting in ethanol concentration, ethanol yield and productivity of 70.7 g L⁻¹, 89.8% and 21.2 g L⁻¹ h⁻¹, respectively. A two-stage reactor was used in the continuous ethanol fermentation of thick juice by feeding fresh yeast cells into the second reactor. This process was stable at a total process dilution rate of 0.11 h⁻¹ with an overall sugar concentration of 190 g L⁻¹ in the influent. The ethanol concentration was kept at approximately 80 g L⁻¹, corresponding to ethanol yield of 82.5% and productivity of 8.8 g L⁻¹ h⁻¹.     

钢管高性能混凝土轴压短柱的静力性能(Ⅱ):机理分析及承载力

研究钢管高性能混凝土轴压短柱中钢管和混凝土的应力、应变等的分布规律,发现圆试件中截面混凝土纵向应力在圆周方向均匀分布,而方试件中截面混凝土的纵向应力在弯角处最大。试件在受荷过程中,中截面钢管首先屈服,然后逐渐向试件两端发展。典型算例的分析结果表明,圆钢管对混凝土的约束作用好于方钢管的,圆钢管对混凝土沿圆周方向均匀约束,而方试件在截面弯角处的约束力最大。所有试件在中截面约束力最大。黏结强度对于试件的轴压承载力基本没有影响。普通钢管混凝土轴压短柱的承载力计算式同样适用于钢管高性能混凝土轴压短柱的承载力计算。钢管高性能混凝土轴压短柱与普通钢管混凝土轴压短柱在静力性能方面并无本质区别。     

钢管高性能混凝土压弯构件的静力性能(Ⅰ):试验研究及有限元模拟

为给辽宁省地方标准的编制提供依据对钢管高性能混凝土压弯构件的静力性能展开研究。通过对24个试件(内填自密实混凝土的立方试块抗压强度标准值为96 MPa)的静力试验,发现钢管高性能混凝土压弯构件的轴力-挠度曲线可以分为弹性阶段、弹塑性阶段和下降段。试件挠曲线接近正弦半波曲线,钢管纵向应变基本符合平截面假定,环向受压的钢管对混凝土没有约束力。应用有限元法模拟试件的轴力-挠度曲线和变形模态,模拟结果与试验结果吻合良好。总体而言,钢管高性能混凝土压弯构件与普通钢管混凝土压弯构件在静力性能方面没有本质区别。     

钢管高性能混凝土压弯构件的静力性能(Ⅱ):机理分析及承载力

为配合辽宁省地方标准《钢管混凝土结构技术规程》的编制,对钢管高性能混凝土压弯构件中钢管和混凝土应力、应变等的分布规律展开研究。对钢管与混凝土相互作用力的研究表明,圆试件受压区的约束力较大,方试件钢管角部区域的相互作用力最大。所有试件中截面受压区的相互作用力最大。黏结强度和加载路径对钢管高性能混凝土压弯构件的静力性能影响都不大。普通钢管混凝土压弯构件的承载力计算式同样适用于钢管高性能混凝土压弯构件的承载力计算。钢管高性能混凝土压弯构件与普通钢管混凝土压弯构件在静力性能方面并无本质区别。     

Research Advancement in High-Performance Polyamides and Polyamide Blends Loaded with Layered Silicate

Polyamide comprises one of the major classes of polymers. Layered silicates (nanofiller) may enhance properties of polyamide-based hybrids even at very low content. Aliphatic polyamides (nylons) have often been chosen for commercial applications because of excellent physical and chemical properties. Aromatic polyamides (aramids) and aliphatic-aromatic polyamides have been predominantly useful as high-performance materials due to stiffness, low density, and low cost. Recently polyamide blends have become an important route to high-performance materials. Binary blends of polyamide/polypropylene, polyamide/polystyrene, polyamide/polymethyl methacrylate, polyamide/polyurethane, and others have been reported for nanocomposite formation with organoclay. However, ternary blend nanocomposite with nanoclays (PA6/mSEBS, PA6/EPDM-g-MA/H-HDPE) is rarely explored.     

复合外加剂对低温高性能混凝土抗渗性的影响

主要研究了在低温高性能混凝土中掺入复合外加剂对混凝土抗渗性能的影响,并按选定配比以最佳掺量掺入低温高性能混凝土中进行抗渗性试验,测试结果满足设计和施工要求.     

Monitoring Phenolic Composition of Maturing Maize Stover by High Performance Liquid Chromatography and Pyrolysis/Gas Chromatography/Mass Spectrometry*

Maize stovers collected every 14 days over an 84-day growth period were subjected to high-performance liquid chromatography with electrochemical detector (HPLC-ED) and pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) in order to monitor changes in the phenolic composition. Prior to HPLC-ED analyses, ground samples were sequentially extracted with (i) methanol, (ii) 0·1M sodium hydroxide and (iii) 2M sodium hydroxide in the presence of nitrobenzene to separate, respectively, free phenolic monomers, alkali-labile phenolic monomers and alkali-resistant lignin. In turn, solution (ii) was treated with alkaline nitrobenzene to obtain (iv) alkali-labile lignin. Pyrolysis was carried out on ground native samples by using a platinum heated filament pyrolyser. Increases in the absolute phenolic concentrations in the residues of 0·1M sodium hydroxide extraction and in the ratio of alkali-resistant lignin vs total lignin were observed by HPLC-ED during the first 28–42 days of maturation, reaching a steady level in the remaining maturation period. A linear increase of syringyl units vs guaiacyl units was for found the alkali-resistant lignin fraction over the entire period of maturation. Similar trends were showed by PY/GC/MS with regard to relative lignin content and syringyl/guaiacyl ratio. Both techniques showed their usefulness to gauge changes in the phenolic composition during the lignification process.     

高效液相色谱-四极杆飞行时间串联质谱法解析桑椹酒渣中的酚类物质

该研究通过研究桑椹酒渣中的酚类化合物,为开发酒渣的价值提供一定的理论基础和数据支撑。建立云桑二号桑椹酒渣中的酚类化合物的高效液相色谱-四极杆飞行时间串联质谱法（HPLC-Q-Time-of-Flight Mass Spectrometry,HPLC-Q-TOF-MS）定性分析方法。液相色谱使用ZORBAX SB-Aq(2.1 mm×100 mm,1.8-Micron）色谱柱,流动相为乙腈和0.1%(V/V）甲酸水溶液,梯度洗脱,采用ESI离子源在负离子模式进行质谱检测。最终鉴定出云桑二号桑椹酒渣中酚类物质共14种。然后利用标准品对照高效液相色谱法（High Performance Liquid Chromatography,HPLC）对高效液相色谱-四极杆飞行时间串联质谱法鉴定出的多酚类化合物进行了定量测定,发现桑椹酒渣中的酚类物质组成与桑椹大致相同。但各单体酚含量总体降低。其中,花青素类酚类物质含量最高的是天竺葵素-3-葡萄糖苷（718.30μg/g）,非花青素类多酚物质含量最高的是儿茶素（1 805.87μg/g）。这些结果表明桑椹酒渣酚类含量丰富,是开发健康食品的良好原料。     

高谱纯度低频信号源的设计与实现

现代物理电子设备的调试、检测和维护经常需要使用高谱纯度的信号源.介绍了一种基于Σ-ΔDAC的高谱纯度信号源的设计和实现方法,设计的信号源的动态范围大于110dB,总谐波畸变好-100dB,远远高于目前市面上可以得到的信号源的指标.