Aggregation behavior of block polyethers with branched structure at air/water surface

The block polyethers with various branch structure, such as TEPA[(PO)₃₆(EO)₁₀₀]₇, TEPA[(PO)₃₆(EO)₁₀₀(PO)₃₆]₇, and TEPA[(PO)₃₆(EO)₁₀₀(PO)₅₆]₇ were synthesized. Moreover, the aggregation behavior was investigated via the measurements of equilibrium surface tension, dynamic surface tension, and surface dilational viscoelasticity, in order to probe the effect of the block structure on the property of the branched block polyethers. The surface tension results show that the efficiency and effectiveness of the block polyethers to lower surface tension increase with the increase of the PO group numbers. The maximum surface excess concentration (Γ_max) values and the minimum occupied area per molecule at the air/water interface (A_min) values of the branched block polyethers obtained from Gibbs adsorption equations increase and decrease with the increases of the PO group numbers, respectively. The dynamic parameters n and t^* representing the diffusion speed of the polyether molecules from bulky solution to the subsurface and from the subsurface to the air/water surface are obtained according to the equation proposed by Rosen. The results show that the n values firstly increase and then decrease and t^* values decrease with the increase of the polyether concentrations. The results of surface dilational viscoelasticity show that the dilational modulus of TEPA[(PO)₃₆(EO)₁₀₀(PO)₅₆]₇ is the largest among the three block copolymers at the low concentration (<1 mg L⁻¹) but that of TEPA[(PO)₃₆(EO)₁₀₀]₇ is the largest at the high concentration (>1 mg L⁻¹).     

On the viscosity of magnetic fluid with low and moderate solid fraction

The design of a pressurized capillary rheometer operating at prescribed temperature is described to measure the viscosity of magnetic fluids (MFs) containing Fe3O4 magnetic nanoparticles (MNPs). The equipment constant of the rheometer was obtained using liquids with predetermined viscosities. Experimentally measured viscosities were used to evaluate different equations for suspension viscosities. Deviation of measured suspension viscosities from the Einstein equation was found to be basically due to the influence of spatial distribution and aggregation of Fe3O4 MNPs. By taking account of the coating layer on MNPs and the aggregation of MNPs in MFs, a modified Einstein equation was proposed to fit the experimental data. Moreover, the influence of external magnetic field on viscosity was also taken into account. Viscosities thus predicted are in good agreement with experimental data. Temperature effect on suspension viscosity was shown experimentally to be due to the shear-thinning behavior of the MFs.     

甲烷在Mo/HZRP-1催化剂上无氧脱氢芳构化反应Ⅰ.Mo/HZRP-1催化剂的催化性能和积炭行为

用高 硅含磷五 员环 沸 石 分子 筛（ 商 品 代号 Ｈ Ｚ Ｒ Ｐ１） 作 为 载体 ，制 备 了 Ｍｏ／ Ｈ Ｚ Ｒ Ｐ１ 催化剂． 与 Ｍｏ／ Ｈ Ｚ Ｓ Ｍ５ 相比， Ｍｏ／ Ｈ Ｚ Ｒ Ｐ１ 对 甲烷无 氧脱氢芳 构化反 应也表现 出较好的 催化 性能 ． 实验过程 中，在反 应气中添 加 Ｎ２ 作 为内标 物，给出包 括甲烷 在 Ｍｏ／ Ｈ Ｚ Ｒ Ｐ１ 上 的结焦量 、转化率 及各产物选 择性在内 的总碳 物料平衡 计算结果 ． 考 察了不同 Ｍｏ 担 载量对催 化剂性 能和 积炭 行为 的影响； 重点考察 了不同 温度焙烧 后２０ ％ Ｍｏ／ Ｈ Ｚ Ｒ Ｐ１ 催化剂 的性能和 积炭行 为． 在 反应的初 始阶段 ，６ ％ Ｍｏ／ Ｈ Ｚ Ｒ Ｐ１ 表 现出 很 高 的 活 性： 反 应 进 行 ３０ ｍｉｎ 时， 甲 烷 转 化 率 为 １１ ％ ， 芳 烃 选 择 性 达８１ ％ ， 而催化 剂的结焦 选择性 仅为１２ ％ ． Ｂ Ｅ Ｔ， Ｎ Ｈ３ Ｔ Ｐ Ｄ 和 催 化反 应等 表 征结 果表 明： Ｍｏ 物种的数量 和状态， 分子筛的 酸强度和 酸量以 及分子筛 的孔道 结构是 决定 甲烷 无氧 脱氢 芳构 化反 应性能和积 炭行为 的关键因 素．     

Two‐injection workflow for a liquid chromatography/LTQ‐Orbitrap system to complete in vivo biotransformation characterization: demonstration with buspirone metabolite identification

The relatively high background matrix in in vivo samples typically poses difficulties in drug metabolite identification, and causes repeated analytical runs on unit resolution liquid chromatography/mass spectrometry (LC/MS) systems before the completion of biotransformation characterization. Ballpark parameter settings for the LTQ‐Orbitrap are reported herein that enable complete in vivo metabolite identification within two HPLC/MS injections on the hybrid LTQ‐Orbitrap data collection system. By setting the FT survey full scan at 60K resolution to trigger five dependent LTQ MS² scans, and proper parameters of Repeat Duration, Exclusion Duration and Repeat Count for the first run (exploratory), the Orbitrap achieved the optimal parallel data acquisition capability and collected maximum number of product ion scans. Biotransformation knowledge based prediction played the key role in exact mass ion extraction and multiple mass defect filtration when the initial data was processed. Meanwhile, product ion extraction and neutral loss extraction of the initial dependent data provided additional bonus in identifying metabolites. With updated parent mass list and the data‐dependent setting to let only the ions on the parent mass list trigger dependent scans, the second run (confirmatory) ensures that all precursor ions of identified metabolites trigger not only dependent product ion scans, but also at or close to the highest concentration of the eluted metabolite peaks. This workflow has been developed for metabolite identification of in vivo or ADME studies, of which the samples typically contain a high level of complex matrix. However, due to the proprietary nature of the in vivo studies, this workflow is presented herein with in vitro buspirone sample incubated with human liver microsomes (HLM). The major HLM‐mediated biotransformation on buspirone was identified as oxidation or hydroxylation since five mono‐ (+16 Da), seven di‐ (+32 Da) and at least three tri‐oxygenated (+48 Da) metabolites were identified. Besides the metabolites 1‐pyrimidinylpiperazine (1‐PP) and hydroxylated 1‐PP that formed by N‐dealkylation, a new metabolite M308 was identified as the result of a second N‐dealkylation of the pyrimidine unit. Two new metabolites containing the 8‐butyl‐8‐azaspiro[4,5]decane‐7,9‐dione partial structure, M240 and M254, were also identified that were formed apparently due to the first N‐dealkylation of the 1‐PP moiety. Copyright © 2009 John Wiley & Sons, Ltd.     

A new biphenyl derivative from an unidentified marine fungus E33

A new biphenyl derivative 3,5′-dihydroxy-4′,5-dimethoxy-2′-methyl-[1,1′-biphenyl]-2-carboxylic acid methyl ester (1), was isolated from the culture broth of a fungus isolated from the rhizosphere soil of mangrove root on the South China Sea. The structure of 1 was determined by comprehensive spectroscopic methods, primarily 2D NMR techniques. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 128–129, March–April, 2008.     

S-SUPERFLUOUS AND S-ESSENTIAL HOMOMORPHISMS

Let R be a ring and S a class of R-modules. S-superfluous epimorphisms and S-essential monomorphisms are introduced and studied in this article. As appli-cations, some new characterizations of yon Neumann regular rings and perfect rings are given. Finally, these notions are also used to study minimal homomorphisms.     

Role of Hydrocarbon Radicals CHx (x=1, 2, 3) in Graphene Growth: A Theoretical Perspective

Many outstanding properties of graphene are blocked by the existence of structural defects. Herein, we propose an important healing mechanism for the growth of graphene, which is produced via plasma‐enhanced chemical vapor decomposition (PECVD), that is, the healing of graphene with single vacancies by decomposed CH₄ (hydrocarbon radical CH_x, x=1, 2, 3). The healing processes undergo three evolutionary steps: 1) the chemisorption of the hydrocarbon radicals, 2) the incorporation of the C atom of the hydrocarbon radicals into the defective graphene, accompanied by the adsorption of the leaving H atom on the graphene surface, 3) the removal of the adsorbed H atom and H₂ molecule to generate the perfect graphene. The overall healing processes are barrierless, with a huge released heat of 530.79, 290.67, and 159.04 kcal mol^?1, respectively, indicative of the easy healing of graphene with single vacancies by hydrocarbon radicals. Therefore, the good performance of the PECVD method for the generation of graphene might be ascribed to the dual role of the CH_x (x=1, 2, 3) species, acting both as carbon source and as defect healer.