Autoignition of varied cetane number fuels at low temperatures

The reactivity of six kerosene based control fuels, specifically formulated for cetane number variation, are investigated by measuring ignition delay time in a heated rapid compression machine. Cetane numbers vary from 30 to 55 (increment of 5) while holding other properties relatively constant by adjusting chemical group composition. Main cetane variation was controlled through the distribution of normal alkanes and isoalkanes, which was fine-tuned using additives. Other fuel properties such as density, viscosity, H/C ratio, etc. were balanced using cyclic compounds and aromatics. Fuels were tested in the RCM at compressed pressures of P_c=?10 and 20?bar, equivalence ratios of ??=?0.25, 0.5 and 1.0, in the low to intermediate temperature range (620?K?≤?T_c?≤?730?K). Relations between cetane number and ignition delay time have been evaluated at multiple test conditions, and further analysis on multistage ignition has been conducted. Ignition delay times of fuels with higher cetane numbers are shorter at these temperatures for most conditions. First stage ignition delay time measurements have been observed to be relatively insensitive to P_c, ?, and fuel type, while deviations in overall ignition delay times are mainly attributed to second stage ignition delay time, impacted by variations in the first stage temperature. Control fuels of this type offer an opportunity to be used in practical experiments to determine the impact of cetane number on combustion dynamics.     

整体柱-金复合基底的制备及其在色素SERS检测的应用

研究工作主要以多孔整体柱材料作为SERS基底,赤藓红作为研究对象,通过调整不同实验条件获得最佳SERS增强效果,其中包括体系酸碱度及混合时间等,最终选取了最佳pH值5.06,混合时间25 min。对比了其与传统金胶基底的增强效果,利用该实验条件将整体柱基底应用于SERS检测色素赤藓红,对不同浓度的赤藓红样品进行SERS检测,对赤藓红的的检测限可达到0.1 μg·mL-1。该方法利用了金纳米粒子在整体柱介孔材料的有效负载,形成的结构有利用SERS信号的增强,并且具有制作简单,稳定性好等特点,为SERS技术应用于违禁添加色素的快速筛查提供了有利的理论基础。     

High-temperature synthesis of SAPO-34 molecular sieve using a dry gel method

SAPO-34 is one of the main catalysts used in the petrochemical industry. Various effective methods have been developed to synthesize SAPO-34 with optimal size and characteristics for such application. In the present study, SAPO-34 was synthesized using a dry gel method at high temperatures. Morpholine was used as an organic template. The products were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and gas sorption analysis. The results showed that application of the dry gel method at high temperatures successfully afforded a pure catalyst with high crystallinity. Small particles of less than 500 nm could be obtained within a short reaction time of 30 min.     

快速高分离度液相色谱-质谱联用方法筛选Tau蛋白激酶2抑制剂

建立了测定Tau 蛋白激酶2(Tau protein kinase 2, TPK2)催化反应产物磷酸化十肽(PKpTPKKAKKL)的快速高分离度液相色谱-质谱方法(RRLC/MS)用于筛选TPK2抑制剂. 反应溶液总体积为50 μL, 将终浓度为20 nmol/L的TPK2与终浓度为5 μmol/L的底物十肽(PKTPKKAKKL)于30 ℃反应30 min, 用等体积乙腈终止反应并加入终浓度为1 μmol/L的磷酸化十肽(PKpTPKKAKKV)作为内标, 采用Agilent SB-C₁₈色谱柱, 以乙腈-水为流动相梯度洗脱分离后, 用RRLC/MS进行定性及定量分析. 该方法可通过精确定量一定时间内的酶促反应产物来反映酶活性被抑制的程度, 作为TPK2抑制剂的筛选方法, 本方法具有简单、 灵敏、 快速的优点, 能够避免光谱法筛选可能产生的假阳性结果, 可用于TPK2的先导化合物的高通量筛选.     

气相色谱-串联质谱法快速检测水果中的多效唑残留

建立了农药残留快速检测(QuEChERS)-气相色谱-串联质谱法检测桃、樱桃和荔枝中多效唑残留的分析方法.样品用乙腈快速提取,无水MgS04和NaCl除水后,经N-丙基乙二胺和石墨化炭黑净化,用气相色谱-串联质谱分析.采用多反应监测正离子模式检测,定性离子对为m/z 236/125,236/167,采用m/z 236/...     

Solvent and catalyst effects on the complexation of toluene with Cr(CO)6

Summary The effect of 8 solvents on the rate as well as the yields of complexation of toluene with Cr(CO)₆ has been studied. It has been found that the intensity of boiling has a profound effect on the rate of complexation in some cases (whenn-hexanol, cyclohexanone or diglyme is used as solvent). The rates of complexation are highest in these cases, but a considerable extent of decomposition results in lower yields. Butyl acetate, dibutyl ether and decalin have been found to be the most feasible solvents. Additionally, 27 different catalysts have been tested for the complexation of toluene in decalin solution, their effect being quantified by rate constants and the isolated yields of the reaction. The rate constants have been obtained from the rate of CO evolution and vary from 6.6·10^–5 s^–1 for formic acid to 6.5·10^–4 s^–1 for ethyl acetamidomalonate. Cycloalkanones proved to be more efficient catalysts than acyclic ketones with a close boiling point. Lactones are more efficient than esters, both cyclic and acyclic ketones, and diesters, all having a similar boiling point.

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Lösungsmittel- und katalytische Effekte bei der Komplexierung von Toluol mit Cr(CO)₆

Zusammenfassung Es wurde der Effekt von 8 Lösungsmitteln auf Komplexierungsgeschwindigkeit und Ausbeute der Komplexbildung von Toluol mit Cr(CO)₆ untersucht. Dabei wurde festgestellt, daß die Intensität der Erhitzung beim Sieden in einigen Fällen einen wesentlichen Effekt auf die Komplexierungsgeschwindigkeit hat (bein-Hexanol, Cyclohexanon und Diglyme). Die Komplexierungsgeschwindigkeit ist in diesen Fällen die größte, die bereits beträchtlich einsetzende Zersetzung ergibt aber geringere Ausbeuten. Butylacetat, Dibutylether und Decalin erwiesen sich als die günstigsten Lösungsmittel. Außerdem wurden 27 verschiedene Katalysatoren für die Komplexierungsreaktion in Decalin als Lösungsmittel getestet und ihre Effizienz durch Geschwindigkeitskonstanten und isolierbare Ausbeute charakterisiert. Die Geschwindigkeitskonstanten wurden aus der Entwicklung von CO berechnet; sie liegen zwischen 6.5·10^–5 s^–1 für Ameisensäure bis zu 6.5·10^–4 s^–1 für Ethylacetamidomalonat. Cycloalkanone erwiesen sich als die besseren Katalysatoren gegenüber acyclischen Ketonen vergleichbaren Siedepunkts. Lactone sind effektvoller als Ester, cyclische sowohl als auch acyclische Ketone und Diester mit ähnlichen Siedepunkten.

     

Rapid screening of bioactive compounds from natural products by integrating 5-channel parallel chromatography coupled with on-line mass spectrometry and microplate based assays

A high throughput method was developed for rapid screening and identification of bioactive compounds from traditional Chinese medicine, marine products and other natural products. The system, integrated with five-channel chromatographic separation and dual UV–MS detection, is compatible with in vitro 96-well microplate based bioassays. The stability and applicability of the proposed method was validated by testing radical scavenging capability of a mixture of seven known compounds (rutin, dihydroquercetin, salvianolic acid A, salvianolic acid B, glycyrrhizic acid, rubescensin A and tangeretin). Moreover, the proposed method was successfully applied to the crude extracts of traditional Chinese medicine and a marine sponge from which 12 bioactive compounds were screened and characterized based on their anti-oxidative or anti-tumor activities. In particular, two diterpenoid derivatives, agelasine B and (−)-agelasine D, were identified for the first time as anti-tumor compounds from the sponge Agelas mauritiana, showing a considerable activity toward MCF-7 cells (IC₅₀ values of 7.84 ± 0.65 and 10.48 ± 0.84 μM, respectively). Our findings suggested that the integrated system of 5-channel parallel chromatography coupled with on-line mass spectrometry and microplate based assays can be a versatile and high efficient approach for the discovery of active compounds from natural products.     

快速石墨炉原子吸收光谱法测定尿铊

尿样用硫酸-硝酸混合酸消化,并用溴水将溶液中铊(Ⅰ)氧化至铊(Ⅲ),用盐酸(1 4)介质使铊(Ⅲ)以络阴离子Tl(Cl)4-状态存在。用聚氨酯泡沫塑料吸附铊(Ⅲ),从而与尿液分离,且达到消除尿液中无机盐的干扰和一定的富集效果。将聚氨酯泡沫塑料取出并洗净后置于沸水中使铊(Ⅲ)从泡沫塑料上解吸,所得溶液供石墨炉原子吸收光谱法(GF-AAS)测定。在方法中不加任何基体改进剂且在石墨平台升温程序中省略了灰化步骤,使测定达到快速的要求。方法的测定限达到0.1μg.L-1,测得回收率在91%~97%之间。     

Fiber-packed needle for dynamic extraction of aromatic compounds

A fiber-packed needle was developed as a novel extraction device for gas-chromatographic analysis of trace organic compounds in aqueous samples. In the extraction device, a bundle of the polymer-coated filaments as the sorbent material was longitudinally packed into a specially designed needle. The extraction was made by pumping the aqueous sample solution into the needle extraction device, and the subsequent desorption process was carried out with a flow of desorption solvent through the needle in a heated gas chromatograph injector. The needle device showed an excellent thermal stability for repeated use without any deterioration of extraction performance, and no carryover effect was observed after the optimization of the desorption conditions. Additionally, the extraction efficiency of the fiber-packed needle could be enhanced by optimizing the number of packed filaments. The selectivity for various compounds could be also tuned using an appropriate combination of the fibrous medium and the coating polymer. The relative standard deviation for run to run was from 3.88 to 4.55% (n = 5), and that for needle to needle was 7.21% (n = 3), clearly suggesting a good repeatability of the needle extraction technique developed. Upon successful optimization of the extraction conditions, a rapid extraction of trace organic compounds from an aqueous sample matrix was successfully demonstrated, where each extraction process was completed within 10 min.     

快速检测巯基化合物的新方法

本文利用巯基化合物对异硫氰酸荧光素(FITC)的荧光猝灭作用,建立了一种快速检测巯基化合物的新方法。实验中发现,巯基化合物能够猝灭FITC的荧光,据此发展了检测巯基化合物的新方法。本方法的用时非常短,在优化了pH、反应时间等条件后能在5min之内完成对巯基化合物的检测。在最佳条件下对实际样品的测试取得了很好的效果,且具有良好的选择性。对谷胱甘肽(GSH)、高半胱氨酸(Hcy)、半胱氨酸(Cys)、二硫苏糖醇(DTT)的检测限分别达到3.08、2.66、1.28和1.92μmol/L。