MgO、Al_2O_3、SiO_2催化剂上湿天然气中乙烷氧化脱氢的研究(英文)

研究了ＭｇＯ、Ａｌ２Ｏ３、ＳｉＯ２催化剂对湿天然气中乙烷氧化脱氢反应的影响，发现ＭｇＯ对乙烷脱氢有较好的活性，７００Ｃ时，Ｃ２Ｈ４选择性达４１．８５％，收率达１８．７５％。考察了催化剂酸碱性对反应的影响，适当碱性的催化剂有利于反应的进行，催化剂活性顺序与碱性大小顺序相一致为ＭｇＯ＞Ａｌ２Ｏ３＞ＳｉＯ２。催化剂活性顺序与其晶格氧流动性有顺应关系。     

Structure and stability of thiourea with water, DFT and MP2 calculations

The relative stabilities of thiourea in water are investigated computationally by considering thiourea–water complexes containing up to 1–6 water molecules (CS(NH₂)₂(H₂O)_n=1–6) using density functional theory and MP2 ab initio molecular orbital theory. The results show that the thiourea complex is stable and has an unusually high affinity for incoming water molecules. The clusters are progressively stabilized by the addition of water molecules, as indicated by the increasing of the binding energy. The binding energy of the cluster to each H₂O molecule is about 33 kJ mol⁻¹ for n=1–5.The C–S bond, N–C bond distance, Mulliken populations and binding energy keep approximately constant as the clusters increase in size with an increasing number of H₂O molecules. As the solvation progresses, the C–S distance increases monotonically while the Mulliken populations on the C–S bond reduces monotonically with the addition of each H₂O molecule, indicating that the C–S bond of the thiourea unit in the clusters is de-stabilized with an increasing number of H₂O molecules. Charge transfers for the clusters are mainly found at N, S atoms of the thiourea.     

L-脯氨酸催化下甲基酮和1-芳基-2,2,2-三氟乙酮的不对称Aldol反应

Direct asymmetric aldol addition of methyl ketones to 2,2,2-trifluoro-1-phenylethanone and its ring-substituted derivatives was achieved using L-proline as a chiral promoter. Various optically active β-trifluoromethyl-β-hydroxy ketones were obtained in almost quantitative yields with moderate enantioselectivities up to 64 % ee.     

线性不对称损失时非正态分布过程均值优化

针对常见的两种非正态分布———梯形分布和三角分布，研究线性不对称质量损失时其过程均值的优化问题，建立了梯形分布在五种不同情况下线性不对称质量损失的数学模型，基于以上模型给出了线性不对称质量损失时梯形分布最优过程均值的确定方法；研究三角分布在四种不同情况下线性不对称质量损失的数学模型，并给出了线性不对称质量损失时三角分布最优过程均值的确定方法。最后，用实例验证本过程均值优化模型的有效性。实例表明，应用线性不对称损失函数，适当的改变过程均值，可以有效地降低产品的质量损失，通过调整工艺过程将获得最佳经济效益。     

Qualitative analysis of Holling type II predator–prey systems with prey refuges and predator restricts

This paper is devoted to investigation of Holling type II predator–prey systems with prey refuges and predator restricts. Using a transformation technique, we change the system into a generalized Liénard system and give sufficient conditions to ensure the global stability of the positive equilibrium and existence and uniqueness of a stable limit cycle. We also find the property of alternation for phase structure of the system.     

Synthesis and Crystal Structure of (Z)-N-(2-(diethylamino)ethyl)-7-(5-fluoro-2-oxoindolin-3-ylidene)-2-methyl-4,5,6,7-tetrahydro-1H-indole-3-carboxamide Methanol Solvate

The crystal structure of a new compound (Z)-N-(2-(diethylamino)ethyl)-7-(5- fluoro-2-oxoindolin-3-ylidene)-2-methyl-4,5,6,7-tetrahydro-1H-indole-3-carboxamidemethanol solvate (C24H29FN4O2CH4O, Mr = 456.55) has been prepared and determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group P21/c with a = 14.560(3), b = 7.3200(2), c = 22.233(4) , β = 101.78(3)°, V = 2319.7(8) 3 , Z = 4, Dc = 1.307 g/cm 3 , F(000) = 976, μ = 0.092 mm -1 , MoKa radiation (λ = 0.71073), R = 0.0604 and wR = 0.1644 for 4262 observed reflections with I > 2 (I). X-ray diffraction analysis reveals that the indole and pyrrole are almost coplanar. Intramolecular C-H···O and N-H···O hydrogen bonds together with π-π interactions are found in the structure.     

An Ultrastable Crystalline Acylhydrazone-Linked Covalent Organic Framework for Efficient Removal of Organic Micropollutants from Water

As an important member of crystalline porous polymers, acylhydrazone-linked covalent organic frameworks (COFs) have gained much attention in recent years. However, the low structural stability imparts a limit on their practical applications. To tackle this problem, we report a simple strategy to increase the chemical stability of acylhydrazone-linked COFs by incorporating azobenzene groups in the conjugated framework. Through reinforcing the π-π stacking interactions between the adjacent layers with increased π-surface, it is surprising to find that the resulting materials exhibit extreme stability in harsh environments, such as in strong acid, strong base, aqueous educing agent and boiling water, even exposed to air for one year. As a proof-of-concept, such frameworks have been used to remove various organic micropollutants such as antibiotics, plastic components, endocrine disruptors, and carcinogens from water with high capacity, fast speed and excellent reusability over a wide pH range at environmentally relevant concentrations. The results provide a new avenue to significantly enhance the stability of COFs for practical applications.     

Quantification and pharmacokinetics of Taiwanin E methyl ether in rats by liquid chromatography–tandem mass spectrometry

This study firstly describes the development of an accurate and sensitive high‐performance liquid chromatography–tandem mass spectrometry (LC‐MS/MS) assay for the quantification of Taiwanin E methyl ether (TEME) in rat plasma. The assay involved a simple liquid–liquid extraction step with ethyl acetate and a gradient elution using a mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid. Chromatographic separation was successfully achieved on an Agilent Zorbax‐C₁₈ column (2.1 × 50 mm, 3.5 µm) with a flow rate of 0.40 mL/min. The multiple reaction monitoring was based on the transitions of m/z = 379.1 → 320.1 for TEME and 386.1 → 122.0 for buspirone (internal standard). The assay was validated to demonstrate the specificity, linearity, recovery, accuracy, precision and stability. The lower limit of quantification was 0.50 ng/mL in 50 μL of rat plasma. The developed and validated method was successfully applied to the quantification and pharmacokinetic study of TEME in rats after intravenous and oral administration of 1.45 mg/kg TEME. The oral absolute bioavailability of TEME was estimated to be 5.85 ± 1.41% with an elimination half‐life value of 2.61 ± 0.55 h, suggesting its poor absorption and/or strong metabolism in vivo. Copyright © 2012 John Wiley & Sons, Ltd.     

Fast analysis of triterpenoids in Ganoderma lucidum spores by ultra‐performance liquid chromatography coupled with triple quadrupole mass spectrometry

A rapid and reliable method was established for simultaneous determination of main triterpenoids in Ganoderma lucidum spores using ultra‐high‐performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC‐TQ‐MS). The established method was validated in terms of linearity, sensitivity, precision, accuracy and stability, and was successfully applied to determine the contents of 10 main triterpenoids in different batches of G. lucidum spores. The analysis results showed that moderate levels of triterpenoids were found in G. lucidum spores. In addition, a MS full scan with a daughter ion scan experiment was performed to identify the potential derivatives of triterpenoids present in G. lucidum spores. As a result, a total of 22 triterpenoids from different G. lucidum spores were unequivocally or tentatively identified via comparisons with authentic standards and literatures. This method provides both qualitative and quantitative results without the need for repetitive UPLC‐MS analyses, thereby increasing efficiency and productivity, making it suitable for high‐throughput applications. Copyright © 2013 John Wiley & Sons, Ltd.