Five New C19‐Diterpenoid Alkaloids from Aconitum hemsleyanum

Five new C₁₉‐diterpenoid alkaloids, named hemsleyaconitines A–E ( 1 – 5 , resp.), were isolated from Aconitum hemsleyanum Pritz. By UV, IR, MS, 1D‐ and 2D‐NMR analyses, their structures were elucidated as 18‐dehydroxygeniculatine D ( 1 ), 6‐hydroxy‐14‐O‐veratroylneoline ( 2 ), 14‐O‐acetyl‐8‐ethoxysachaconitine ( 3 ), 18‐veratroylkaracoline ( 4 ) and 8‐O‐ethylaustroconitine B ( 5 ).     

Synthesis,Structure, and Magnetic Properties of Three Novel Sandwich‐type Tungstobismuthates with Triethanolamine

Three novel sandwich‐type polyoxotungstates ( 1 – 3 ) were synthesized in good yield using an in‐situ conventional solution synthesis method by reaction in aqueous media below 80 °C. Compounds 1 – 3 represent the first structurally characterized β‐B‐BiW₉ sandwich‐type polyoxometalates with triethanolamine cations. All three compounds have the same building unit [(X(H₂O)₃)₂(X_0.5W_0.5O)₂(β‐B‐BiW₉O₃₃)₂)]^10– [X = Mn^II ( 1 ), Co^II ( 2 ), Ni^II ( 3 )]. The adjacent units of 1 or 2 are joined by Na⁺ cations in different ways to construct 1D chains or 2D sheets. A 3D supramolecular structure is further formed by hydrogen bond interactions among water molecules and protonated triethanolamine cations. Meanwhile only compound 3 shows a 0D structure. The compounds were characterized by elemental analysis, IR spectroscopy, TG analysis, and single‐crystal X‐ray diffraction. Magnetic measurements on a sample of 1 show the presence of paramagnetic interactions.     

Resonance Rayleigh scattering method for the determination of polyvinylpyrrolidone using eosin Y as the probe

The intensities of resonance Rayleigh scattering (RRS) of poly (vinyl pyrrolidone) (PVP) and of eosin Y (EY) are weak in solutions of pH 2.9 to 3.4. If reacted with each other, the intensities of RRS are largely enhanced and new RRS bands appear at 276 nm and 320 nm. The intensity at 276 nm is linearly related to the concentration of PVP in the range from 0.10 to 1.6 μg mL^-1. The correlation coefficient is 0.9987, and the detection limit is 28.7 ng mL^-1. The binding mode between PVP and EY was studied by RRS, and by absorption and fluorescence spectroscopy. The optimum reaction conditions and some potential interferences were investigated. The method displays good selectivity and was applied to the determination of PVP in beer.     

Synthesis and calming activity of helicid derivatives containing the 3,4-dihydropyrimidin-2(<Emphasis Type="Italic">H</Emphasis>)-one and 3,4-dihydropyrimidine-2(<Emphasis Type="Italic">H</Emphasis>)-thione moiety

A series of novel helicid derivatives containing 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine2(1H)-thione moiety (3a–3f and 4a–4f) were synthesized starting from helicid. The structure of the new compounds were characterized by ¹H NMR, IR and HR-MS spectra. The sedative-hypnotic activities of the target compounds were evaluated using the test of spontaneous locomotor activity in mice. All of the derivatives produced moderate to high activities; in particular, compound 4a presented the most potent sedative-hypnotic effect in comparison to the other derivatives, and derivatives 3a, 3c, 3d, 3e and 3f also showed potent activities.     

LC Analysis of Hexafluorophosphate on a Monolithic Column: Application to the Analysis of Ionic Liquids

A silica-based monolithic column with tetrabutylammonium hydroxide–phthalic acid–acetonitrile as mobile phase has been used for LC analysis of hexafluorophosphate with direct conductivity detection. The effects of mobile phase composition, column temperature, and flow rate on retention of hexafluorophosphate were investigated and the optimum chromatographic conditions were selected. Common anions and tetrafluoroborate did not interfere with analysis of hexafluorophosphate. The detection limit (S/N = 3) for hexafluorophosphate was 6.2 mg L^?1. Relative standard deviation (n = 5) for peak area was 0.1%. The method was successfully used for analysis of hexafluorophosphate in ionic liquids.     

LC-MS/MS determination and pharmacokinetic study of albiflorin and paeoniflorin in rat plasma after oral administration of Radix Paeoniae Alba extract and Tang-Min-Ling-Wan

A rapid, sensitive and selective liquid chromatography/tandem mass spectrometry method (LC‐MS/MS) was developed and validated for simultaneous determination of albiflorin and paeoniflorin in rat plasma using geniposide as an internal standard. Plasma samples were extracted by solid‐phase extraction. Chromatographic separation was carried out on a Zorbax SB‐C₁₈ analytical column (150 × 2.1 mm × 5 µm) with 0.1% formic acid–acetonitrile (70:30, v/v) as the mobile phase. Detection was performed by multiple reaction monitoring mode using electrospray ionization in the positive ion mode. The total run time was 3.0 min between injections. The calibration curves were linear over a range of 1–1000 ng/mL for albiflorin and 2–2000 ng/mL for paeoniflorin. The overall precision and accuracy for all concentrations of quality controls and standards were better than 15%. Mean recovery was determined to be 87.7% for albiflorin and 88.8% for paeoniflorin. The validated method was successfully applied to the pharmacokinetic study of albiflorin and paeoniflorin in rat plasma after oral administration of Radix Paeoniae Alba extract and Tang‐Min‐Ling‐Wan. The pharmacokinetic parameters showed that albiflorin and paeoniflorin from Tang‐Min‐Ling‐Wan were absorbed more rapidly with higher concentrations in plasma than that from Radix Paeoniae Alba extract. The results provided a meaningful basis for evaluating the clinical applications of traditional Chinese medicine. Copyright © 2010 John Wiley & Sons, Ltd.     

d-glucose Enhanced 5-Aminolevulinic Acid Production in Recombinant Escherichia coli Culture

In this study, we introduced a new strategy, feeding d-glucose, to overproduce extracellular 5-aminolevulinic acid (ALA) in the recombinant Escherichia coli. We investigated that the d-glucose concentration is dependent on extracellular ALA production. The results indicated that increasing d-glucose concentration in bacteria culture enhanced final cell density and ALA yield and simultaneously decreased the activities of ALA synthase (ALAS) and ALA dehydratase (ALAD); then, the inhibitory effect of d-glucose on ALAS activity was relieved with the metabolism of d-glucose. when 4.0 g/L d-glucose was added at late exponential phase; 1.46 g/L ALA was achieved in shaking culture, which is 47% or 109% higher than the ALA yields with 30 mM levulinic acid of ALAD inhibitor or no inhibitor. In jar fermenter, final extracellular ALA concentration reached 3.1 g/L by feeding with d-glucose.     

Culture of Microalgae <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> in Wastewater for Biomass Feedstock Production

The objective of this research was to develop large-scale technologies to produce oil-rich algal biomass from wastewater. The experiments were conducted using Erlenmeyer flasks and biocoil photobioreactor. Chlamydomonas reinhardtii was grown in artificial media and wastewaters taken from three different stages of the treatment process, namely, influent, effluent, and centrate. Each of wastewaters contained different levels of nutrients. The specific growth rate of C. reinhardtii in different cultures was monitored over a period of 10 days. The biomass yield of microalgae and associated nitrogen and phosphorous removal were evaluated. Effects of CO₂ and pH on the growth were also studied. The level of nutrients greatly influenced algae growth. High levels of nutrients seem to inhibit algae growth in the beginning, but provided sustained growth to a high degree. The studies have shown that the optimal pH for C. reinhardtii is in the range of 7.5. An injection of air and a moderate amount of CO₂ promoted algae growth. However, too much CO₂ inhibited algae growth due to a significant decrease in pH. The experimental results showed that algal dry biomass yield reached a maximum of 2.0 g L⁻¹ day⁻¹ in the biocoil. The oil content of microalgae of C. reinhardtii was 25.25% (w/w) in dry biomass weight. In the biocoil, 55.8 mg nitrogen and 17.4 mg phosphorus per liter per day were effectively removed from the centrate wastewater. Ferric chloride was found to be an effective flocculent that helps the algae settle for easy harvest and separation from the culture media.     

覆铜板基材介电性能的自动温控测试系统

该文介绍了自行组建的针对微波频段(1GHz～15GHz)覆铜板基材介电常数Dk和介电损耗角正切Df的自动温控测试系统。该系统由个人工作站电脑进行控制,通过Delta9039精密烘箱控制实验温度环境,温度范围为-55℃～85℃,采用安捷伦N5230A矢量网络分析仪对基材进行散射参数S和品质因子Q的测试,自动采集并记录测试数据。使用该系统对普通FR-4、无卤FR-4和Low-Dk、FR-4进行Dk和Df测试,效果良好。     

多径超宽带接收机的研究和仿真

对多径IR-UWB信号的Rake接收技术原理和结构进行了详细分析。在此基础上仿真了不同Rake接收机的性能,包括部分Rake和选择性Rake,以及具有不同叉指的Rake接收机的性能。仿真结果表明在具有相同叉指条件下,选择性Rake接收机比部分Rake接收机的性能高出3dB。而在相同接收原理下,叉指越多,接收机的性能越好。而2路选择性Rake接收机和5路部分Rake接收机在较低信噪比的情况下,性能并无很大差别。