NMR metabolic profiling of organic and aqueous sea bass extracts: implications in the discrimination of wild and cultured sea bass

The nuclear magnetic resonance (NMR) technique was used as analytical tool to determine the complete metabolic profiling of sea bass extracts: water-soluble metabolites belonging to different classes such as sugars, amino acids, dipeptides and organic acids as well as metabolites soluble in organic solvent such as lipids, sterols and fatty acids were identified. The metabolite profiling together with a suitable statistical analysis were used to discriminate between wild and cultured sea bass samples. Preliminary results show that discrimination between wild and cultured sea bass was obtained not only using fatty acid composition but also cholesterol and phosphatidylethanolamine and some water-soluble metabolites such as choline, trimethylamine oxide, glutamine, fumaric and malic acids.     

Necking in Extrusion Film Casting: Numerical Predictions of the Maxwell Model and Comparison with Experiments

The role of viscoelasticity in determining the extent of necking of a web of molten polymer extruded in an isothermal steady state extrusion film casting (EFC) process is considered. Following a brief review of experimental and theoretical efforts on this problem, analytical and numerical solutions to a well-established model for extrusion film casting using the Maxwell constitutive equation is presented. The extent of film necking was found to either increase or decrease with draw ratio (DR) depending on the Deborah number (De). The locus of points on the draw ratio-Deborah number diagram at which the draw ratio dependence of the necking width inverts was calculated and compared with the locus that separates the unattainable regime from the experimentally accessible regime. Predicted trends were found to be in qualitative agreement with experimental data for various polyethylene grades.     

长链阳离子表面活性剂蠕虫状胶束的剪切带转变行为研究

报道一种含有不饱和疏水尾链的超长链阳离子表面活性剂——N-芥酸酰胺丙基-N,N,N-三甲基碘化铵(EDAI)自组装所形成的蠕虫状胶束及其剪切带行为. EDAI浓溶液表现出了明显的剪切带转变特征, 即溶液的流动曲线被介于两个临界剪切速率之间的剪切应力平台分割为粘度不同的两部分. 在剪切带转变区域, 原本均质的流体表现出机械剪切不稳定性, 沿速度梯度方向被分割为剪切速率不同的两个宏观流体层.     

南海黄蜂海绵中系列长链甲基酮成分分析

从中国南海海绵Spheciospongia Vagabunda乙酸乙酯萃取部分中分离出一组混合物,应用^13HNMR,^13CNMR,H-HCOSY和GC／MS等光谱分析技术对它们的结构进行了分析,主要为一些长链甲基酮化合物。共鉴定出二十四碳烯-2-酮异构体、二十四碳二烯-2-酮和二十四碳烯-2-酮等14种化合物,其中4种化合物的双键位置有待于进一步确定。     

制备方法对Pt-Sn-K-Mg/γ-Al2O3催化剂正十二烷脱氢性能的影响

以正十二烷脱氢反应为探针反应,采用顺序浸渍、乙醇共浸渍、盐酸共浸渍的方法制备了Pt-Sn-K-Mg/γ-Al2O3催化剂,并采用NH3-TPD、CO脉冲吸附、H2-TPR、准原位XPS等表征手段探究浸渍顺序和溶剂对催化剂构效关系的影响。结果表明,盐酸水溶液共浸渍的方法制备的催化剂表现出了最佳的初始活性和较好的稳定性。催化剂的弱酸性位点的增加有利于Pt的分散,从而提高催化性能。采用乙醇为溶剂的共浸渍方法更有利于PtSn间形成更强的相互作用生成更多的PtSn合金,这对初始活性不利,但对选择性影响较小。     

Influence of Tween 80 on lipid metabolism of an Aspergillus niger strain

Addition of 0.1% of nonionic surface-active Tween 80 to a medium optimized for pectolytic enzyme production of Aspergillus niger increased the amount of enzymes excreted by 70%. In the presence of Tween 80 the amount of sterol esters and triacylglycerols was increased. During the course of cultivation the amounts of precursors for ergosterol biosynthesis diminished with an increase of ergosterol. A. niger incorporated cholesterol from the medium, partly converting it to cholesterol esters. Sterol esters were formed only with selected fatty acids. Oleic acid, the hydrophobic part of Tween 80, was mainly incorporated in phospholipids and glycolipids.     

Synthesis of amino terminated semifluorinated long-chain alkanethiols

The α,ω-diiodoperfluorooctane is added to undecyl-10-en-1-ol through AIBN initiation yielding the monoadduct in good yield (1,2-dichloroethane, 52%). This is added to N-allylphthalimide (AIBN initiation, 1,2-dichloroethane, 81%). The resulting diiodo compound is hydrodeiodinated with Bu₃SnH (toluene, 70%) and the alcohol function is converted to thioacetate through the Mitsunobu reaction (PPh₃, DIAD, THF, 75%). The two protecting groups, phthalimide and thioacetate, are removed with hydrazine to give the expected amino terminated semifluorinated long-chain alkanethiol (ethanol, 80%). This compound has been designed in order to form mixed fluorinated self-assembled monolayers (SAMs) with semifluorinated long-chain alkanethiol giving access to a new platform system for biosensors. Similar results are reported starting from the α,ω-diiodoperfluorohexane.     

A CONVENIENT SYNTHESIS OF LONG-CHAIN 3-n-ALKYLTHIOPHENES AND 3-n- ALKYLFURANS

Abstract

The syntheses of 3-substituted long-chain furans and thiophenes by a Wittig reaction are described. ¹H-NMR and UV data of these compounds are reported.