Cooperation of reducing species for NO reduction over Ag/Al2O3 under oxidizing conditions

Summary The cooperation effect of reducing species for selective reduction of NO over Ag/Al₂O₃ has been investigated in the presence of excess oxygen. When the combinations of propene or propane and ethanol or methanol were used as reducing agents, NO reduction took place over a wider temperature range, compared with a single hydrocarbon as reducing agent.     

超高效液相色谱-三重四极杆质谱法测定血浆和尿液中马桑亭和马桑宁

建立了超高效液相色谱-三重四极杆质谱联用技术测定血浆和尿液中马桑中毒标志物马桑亭和马桑宁的方法。血浆和尿液样品经固相支持液液萃取法提取净化后，溶于15%（v/v）甲醇水溶液中，以Cortecs C₁₈色谱柱（100 mm×2.1 mm，1.6 μm）作为分析柱进行分离，电喷雾负离子多反应监测（MRM）模式下检测，以氟苯尼考作为内标物，基质工作曲线内标法定量。血浆和尿液中马桑亭和马桑宁的平均加标回收率为86.2%~110%，相对标准偏差为5.1%~14.6%（n=6），血浆中马桑亭和马桑宁的检出限（S/N=3）分别为0.01 μg/L和0.1 μg/L，尿液中马桑亭和马桑宁的检出限分别为0.03 μg/L和0.3 μg/L。本法简单、灵敏、准确，可用于血浆和尿液中马桑亭和马桑宁的中毒检测。     

Pd-SiW12/SiO2催化剂上乙烯直接氧化制乙酸的反应机理

 利用积分反应器和微分反应器对Pd－SiW12／SiO2催化剂上乙烯直接氧化生成乙酸的反应机理进行了探讨．乙烯在积分反应中氧化的主要产物为乙酸（选择性为77．6％），很少生成乙醛（选择性仅为8．1％）；而在微分反应中氧化的主要产物是乙醛（选择性为98．4％）．在微分反应中分别以乙醛和乙醇为主反应物时，乙醛氧化完全生成乙酸，选择性为100％，而乙醇氧化生成乙酸的选择性低于0．15％．可以认为，在Pd－SiW12／SiO2催化剂上，水蒸气存在下乙烯主要经由中间物乙醛而生成乙酸．通过对含有不同组分和不同还原条件处理的催化剂活性的比较，认为目的反应主要发生在Pd与SiW12相互接触的部位，催化剂中的Pd0是活性Pd物种的主要形态．     

茂铁基稀土铈配合物的合成与结构

本文利用单羧基二茂铁Fc-COOH和1，1′-二羧基二茂铁HOOC-Fc-COOH作为配体分别合成了双核铈配合物Ce₂(FcCOO)₆ (1)和二维层状配位聚合物Ce₂(OOC-Fc-COO)₃(2)，测定了两种配合物的晶体结构。配合物1中的金属铈离子为九配位结构，分别与周围的羧基二茂铁上的氧原子和作为辅助配体的水分子配位，茂铁间的π-π相互作用将配合物1的二聚体单元连结在一起形成二维的网状结构。配合物2中的金属铈离子亦为九配位结构，分别与周围的羧基二茂铁上的氧原子，作为辅助配体的水分子和甲醇配位形成类似于配合物1的二聚体单元，1，1′-二羧基二茂铁HOOC-Fc-COOH作为桥基配体将二聚体单元连结在一起，形成二维网状的配位聚合物。     

LC Determination of Curcumin in Dog Plasma for a Pharmacokinetic Study

A rapid, simple, and sensitive high-performance liquid chromatographic method for quantification of curcumin in dog plasma has been developed and validated. After addition of the internal standard (berberine), plasma was acidified and extracted with ethyl acetate. Analysis was performed on a C₁₈ column. The mobile phase was acetonitrile–5% acetic acid, 52:48 (v/v) and the flow rate 1.0 mL min^?1. The eluent was monitored at 425 nm. Chromatographic separation was achieved in less than 7 min and the calibration plot was linear over the concentration range 2–128 ng mL^?1. Intra- and inter-assay variability were less than 7.3%. The accuracy ranged from 98.7 to 105.0%. The method was successfully applied to a pharmacokinetic study of curcumin in dogs.     

用DCC/DMAP合成N-苄氧羰基氨基酸薄荷酯

以乙腈为溶剂, 用DCC/DMAP偶合法合成了5个N-苄氧羰基氨基酸薄荷酯, 产率90%～94%. 起始原料氨基酸包括: 甘氨酸, DL-蛋氨酸, β-丙氨酸, L-缬氨酸和L-脯氨酸. 给出了目标产物的氢谱、碳谱、红外光谱、质谱、高分辨质谱和元素分析数据.     

Ar n HF van der Waals clusters revisited. I. New low-energy isomeric structures for n=6-13

New low-lying isomeric structures of Ar(n)HF clusters are reported for n=6-13. They were determined using simulated annealing and evolutionary programming, for pairwise additive intermolecular potential energy surfaces. New global minima were found for the clusters with n=7, 10, 11. The new lowest-energy structure of Ar(7)HF and several new local minima for n=6, 7 clusters have the HF bound on a threefold surface site, consistent with the recent spectroscopic data for Ar(n)HF clusters in helium nanodroplets. A new type of low-energy local minima were determined for n=9-13 clusters.     

A visible-light activated [2 + 2] cycloaddition reaction enables pinpointing carbon–carbon double bonds in lipids

The precise location of C C bonds in bioactive molecules is critical for a deep understanding of the relationship between their structures and biological roles. However, the traditional ultraviolet light-based approaches exhibited great limitations. Here, we discovered a new type of visible-light activated [2 + 2] cycloaddition of carbonyl with C C bonds. We found that carbonyl in anthraquinone showed great reactivities towards C C bonds in lipids to form oxetanes under the irradiation of visible-light. Combined with tandem mass spectrometry, this site-specific dissociation of oxetane enabled precisely locating the C C bonds in various kinds of monounsaturated and polyunsaturated lipids. The proof-of-concept applicability of this new type of [2 + 2] photocycloaddition was validated in the global identification of unsaturated lipids in a complex human serum sample. 86 monounsaturated and polyunsaturated lipids were identified with definitive positions of C C bonds, including phospholipids and fatty acids even with up to 6 C C bonds. This study provides new insights into both the photocycloaddition reactions and the structural lipidomics.

A new visible-light activated [2 + 2] cycloaddition reaction was discovered and enabled pinpointing carbon–carbon double bonds in lipids.     

Magnetic, electronic, and structural characterization of nonstoichiometric iron oxides at the nanoscale

We have investigated the structural, magnetic, and electronic properties of nonstoichiometric iron oxide nanocrystals prepared by decomposition of iron(II) and iron(0) precursors in the presence of organic solvents and capping groups. The highly uniform, crystalline, and monodisperse nanocrystals that were produced enabled a full structural and compositional survey by electron microscopy and X-ray diffraction. The complex and metastable behavior of nonstoichiometric iron oxide (wüstite) at the nanoscale was studied by a combination of Mossbauer spectroscopy and magnetic characterization. Deposition from hydrocarbon solvents with subsequent self-assembly of iron oxide nanocrystals into superlattices allowed the preparation of continuous thin films suitable for electronic transport measurements.