铬天青S–盐酸氯丙嗪–溴化十六烷基三甲铵光度法测定水样中的铁

采用铁(Ⅲ)–铬天青S–盐酸氯丙嗪–溴化十六烷基三甲铵(CTMAB)四元配合物光度法测定水样中铁的含量。在pH 5.50的HAc–NaAc缓冲介质中,在铁(Ⅲ)–铬天青S–盐酸氯丙嗪显色反应中,加入CTMAB,四元配合物的表观摩尔吸光系数为9.85×10~4 L/(mol·cm),是三元配合物灵敏度的两倍。结果表明,配合物在657nm波长处有最大吸收,Fe(Ⅲ)的质量浓度在0~20μg/(25 mL)范围内与吸光度呈良好的线性关系,线性相关系数为0.999 6,方法的检出限为1.84×10~(–3) mg/L。样品加标回收率为97.3%~98.8%,测定结果的相对标准偏差为1.9%~3.2%(n=5)。该方法灵敏度高,精密度与准确度好,便于在实验室推广应用。     

Oxidative Cleavage of C=S and P=S Bonds at an AlI Center: Preparation of Terminally Bound Aluminum Sulfides

The treatment of cyclic thioureas with the aluminum(I) compound NacNacAl ( 1 ; NacNac=[ArNC(Me)CHC(Me)NAr]^?, Ar=2,6‐Prⁱ₂C₆H₃) resulted in oxidative cleavage of the C=S bond and the formation of 3 and 5 , the first monomeric aluminum complexes with an Al=S double bond stabilized by N‐heterocyclic carbenes. Compound 1 also reacted with triphenylphosphine sulfide in a similar manner, which resulted in cleavage of the P=S bond and production of the adduct [NacNacAl=S(S=PPh₃)] ( 8 ). The Al=S double bond in 3 can react with phenyl isothiocyanate to furnish the cycloaddition product 9 and zwitterion 10 as a result of coupling between the liberated carbene and PhN=C=S. All novel complexes were characterized by multinuclear NMR spectroscopy, and the structures of 5 , 9 , and 10 were confirmed by X‐ray diffraction analysis. The nature of the Al=S bond in 5 was also probed by DFT calculations.     

Single‐Electron Transfer between CuX2 and Thiols Determined by Extended X‐Ray Absorption Fine Structure Analysis: Application in Markovnikov‐Type Hydrothiolation of Styrenes

Transition‐metal mediated C?S bond formation using thiol compounds has been widely used in recent years. However, there has been less focus on the interaction between the metal and thiol compounds. In this work, we have successfully evidenced the single‐electron transfer between CuX₂ and thiophenol utilizing EXAFS. The fitting EXAFS results reveal that two halide anions are coordinated with the Cu^I center, whereas no sulfur atom is observed in the first coordination sphere. This Cu^I ate complex serves as the key intermediate for the proton transfer in the application of Markovnikov‐type hydrothiolation reactions.     

Two new dammarane-type triterpene sapogenins from Chinese red ginseng

Two new dammarane-type triterpene sapogenins were isolated from the Chinese red ginseng. The new sapogenins were named as 24,26-dihydroxy-panaxdiol (1) and 24-hydroxy-panaxdiol (2). Their structures were elucidated by the combined analysis of NMR and mass spectrometry as 20(S),25(R)-epoxydammarane-3β,12β,24β,26-tetraol (1) and 20(S),25-epoxydammarane-3β,12β,24α-triol (2). The complete signal assignments of the two compounds were carried out by 2D NMR spectral and NOE differential spectroscopy analysis.     

Terrenolide S,a new antileishmanial butenolide from the endophytic fungus Aspergillus terreus

Terrenolide S, a new butenolide derivative (6), together with six known compounds: (22E,24R)-stigmasta-5,7,22-trien-3-β-ol (1), stigmast-4-ene-3-one (2), stigmasta-4,6,8(14),22-tetraen-3-one (3), terretonin A (4), terretonin (5) and butyrolactone VI (7) have been isolated from the endophytic fungus Aspergillus terreus isolated from the roots of Carthamus lanatus (Asteraceae). Their structures were established by extensive spectroscopic analyses (1D, 2D NMR and HRESIMS), as well as optical rotation measurement and comparison with literature data. Compound 1 displayed a potent activity towards methicillin-resistant Staphylococcus aureus (MRSA) and Cryptococcus neoformans with IC₅₀ values of 2.29 and 10.68 µM, respectively. Moreover, 1, 2 and 6 exhibited antileishmanial activity towards Leishmania donovani with IC₅₀ values of 11.24, 15.32 and 27.27 µM, respectively and IC₉₀ values of 14.68, 40.56 and 167.03 µM, respectively.     

Sobolev estimates for (pseudo)‐differential operators and applications

In this work we show that if is a linear differential operator of order ν with smooth complex coefficients in from a complex vector space E to a complex vector space F, the Sobolev a priori estimate holds locally at any point if and only if is elliptic and the constant coefficient homogeneous operator is canceling in the sense of Van Schaftingen for every which means that Here is the homogeneous part of order ν of and is the principal symbol of . This result implies and unifies the proofs of several estimates for complexes and pseudo‐complexes of operators of order one or higher proved recently by other methods as well as it extends —in the local setup— the characterization of Van Schaftingen to operators with variable coefficients.     

基于ARM处理器的运动目标检测与跟踪系统

运动目标的检测及跟踪技术广泛应用于军事与民用领域。传统基于PC的目标跟踪系统不能满足对体积、功耗及便携性的需求,基于ARM处理器S3C2440A和嵌入式Linux操作系统构建了一个比较完整、实用的目标跟踪系统。该系统利用摄像头采集运动目标图像,处理器进行数字图像处理,LCD显示跟踪目标。阐述了实现原理及图像获取、目标检测、图像分割和目标跟踪算法程序流程。通过实际测试,该系统能满足对低速运动目标的检测、识别和跟踪,且具有较好的实时性和稳定性。     

基于S12X系列双核单片机的CAN网关设计

集成XGATE协处理器内核的S12XE系列双核单片机具有处理速度快、反应时间短、功耗低等优点,在嵌入式应用中具有独特优势和很好的应用前景。本文采用16位双核单片机MC9S12XEQ512作为主控制器,以集成信号和电源隔离功能的CAN收发器芯片ADM3053来实现CAN接口电路,设计并实现了一个可以连接3个CAN通信子网的CAN网关,有效实现了系统的小型化、低功耗、低成本。采用双核处理技术来优化CAN网关的处理流程,由协处理器XGATE来处理各种中断,S12X主CPU则专注于协议处理和消息转发。实际应用表明,系统运行稳定可靠,与传统的采用单处理器实现的CAN网关相比,系统的数据吞吐能力和实时性得到了明显改善。     

Development of a quality evaluation method for Fructus schisandrae by pressurized capillary electrochromatography

A pressurized CEC (pCEC) method with postcolumn detection cell had been developed for quantifying the lignans from Fructus schisandrae extracts. The effects of different experimental conditions, such as the ACN content of the mobile phase, the concentration and pH of the buffer, the applied voltage, and the supplementary pressure were studied. Five lignans (schisandrin, gomisin A, schisantherin C, deoxyschizandrin, schisandrin B) were baseline separated using a mobile phase of ACN-phosphate buffer (pH 5.4; 5 mM) (40:60 v/v) under -4 kV applied voltage. The method showed the satisfactory retention time and peak area repeatability. The calibration curves were linear in the range 50.0-1000.0 microg/mL for schisandrin, 20.0-500.0 microg/mL for gomisin A, 10.0-200.0 microg/mL for schisantherin C, 20.0-500.0 microg/mL for deoxyschizandrin, and 20.0-500.0 microg/mL for schisandrin B. The correlation coefficients were between 0.9978 and 0.9989. With this pCEC system, fingerprints of F. schisandrae were preliminarily established to distinguish two members S. chinensis (Turcz.) Baill. and S. sphenanthera Rehd. Et Wils. of F. schisandrae by characteristic peaks, and evaluate the quality of various sources of raw materials by determining the contents of the five lignans.