Involvement of SgvP in Carbon–Sulfur Bond Formation during Griseoviridin Biosynthesis

Griseoviridin (GV) is an A‐type streptogramin antibiotic displaying antimicrobial activity and acting synergistically with viridogrisein (VG). Bioinformatic analyses reveal SgvP as the sole cytochrome P450 enzyme in the GV/VG gene cluster. To explore the role of SgvP in the GV/VG pathway, we inactivated the sgvP gene. The resulting ΔsgvP mutant generated two new products: GV‐1 and GV‐2, both lacking the C?S bridge. In trans complementation of the sgvP gene into the ΔsgvP mutant strain partially restores GV production. Feeding [1‐¹³C]‐labeled cysteine to the wild‐type strain led to enrichment of C‐7 in the GV scaffold, thus verifying that the C?S bond in GV is formed through direct coupling of the free ?SH group provided by the side chain of cysteine. The above results highlight the significance of SgvP in C?S bond formation in griseoviridin biosynthesis.     

恩施城区典型区域水体中磺胺类药物的检测评价

采用紫外分光光度法研究了恩施城区典型区域(医院、污水处理厂、水产养殖厂)水体中的磺胺类药物(主要为磺胺嘧啶和磺胺甲唑)残留含量。结果表明,这几个典型区域水体中均有磺胺类药物检出,所检出的磺胺甲唑的浓度高于磺胺嘧啶,某污水处理厂的磺胺类药物浓度最高,检出浓度可达微克级。     

Diaryl‐Substituted Azolylthioacetamides: Inhibitor Discovery of New Delhi Metallo‐β‐Lactamase‐1 (NDM‐1)

The emergence and spread of antibiotic‐resistant pathogens is a global public health problem. Metallo‐β‐lactamases (MβLs) such as New Delhi MβL‐1 (NDM‐1) are principle contributors to the emergence of resistance because of their ability to hydrolyze almost all known β‐lactam antibiotics including penicillins, cephalosporins, and carbapenems. A clinical inhibitor of MBLs has not yet been found. In this study we developed eighteen new diaryl‐substituted azolylthioacetamides and found all of them to be inhibitors of the MβL L1 from Stenotrophomonas maltophilia (K_i<2 μM ), thirteen to be mixed inhibitors of NDM‐1 (K_i<7 μM ), and four to be broad‐spectrum inhibitors of all four tested MβLs CcrA from Bacteroides fragilis, NDM‐1 and ImiS from Aeromonas veronii, and L1 (K_i<52 μM ), which are representative of the B1a, B1b, B2, and B3 subclasses, respectively. Docking studies revealed that the azolylthioacetamides, which have the broadest inhibitory activity, coordinate to the Zn^II ion(s) preferentially via the triazole moiety, while other moieties interact mostly with the conserved active site residues Lys224 (CcrA, NDM‐1, and ImiS) or Ser221 (L1).     

Pt/SAPO-11催化费托合成油选择性加氢异构化制备替代喷气燃料

采用自制Pt/SAPO-11催化剂,以煤基费托合成中间馏分油为原料进行选择性加氢异构反应,制备替代喷气燃料。考察了温度对反应的影响,研究了不同总转化率下产物的分布规律,测定了产物的基本理化性质。实验结果表明,温度对总转化率的影响显著,从310℃时的约18%可增至380℃时的约91%;在310~355℃内,异构烃的选择性几乎恒定且超过85%,高于355℃时则下降。随总转化率的增加,原料中不同碳数的正构烃逐渐转化为单支链异构体,进而转变为多支链异构体;总转化率为82.11%时,异构体收率达到最大值(72.60%)。产物的密度、闪点和黏度随总转化率变化很小,冰点随总转化率的升高而下降。当总转化率达47.00%时,产物的各项物性均满足美国军用标准MIL-DTL-83133E中替代喷气燃料的要求。     

新型制冷剂R1234ze(E)及其混合工质研究进展

低GWP值制冷剂R1234ze(E)(trans-1,3,3,3-tetrafluoropropene)作为R134a较为理想的替代品而被关注,但其单一成分的热力学性能和传输特性并不理想,在R1234ze(E)中混入R32成分可以有效改善其热力学性能。本文概述了低GWP值工质R1234ze(E)及其与R32混合物的热物性特征、传输特性及系统运行性能方面的研究现状,并与目前常用的制冷工质进行比较分析,指出R1234ze(E)与R32混合工质有望成为新型低GWP值替代工质。     

Self‐Defensive Coating for Antibiotics Degradation—Atmospheric Pressure Chemical Vapor Deposition of Functional and Conformal Coatings for the Immobilization of Enzymes

Conformal epoxy‐rich coatings are synthesized by plasma initiated chain‐growth polymerization of glycidyl methacrylate via a newly developed Plasma initiated chemical vapor deposition method at atmospheric pressure to provide a functional platform for the immobilization of enzymes degrading antibiotics (laccase and β‐lactamase). In addition to enhance the enzymes activity duration and intensity, surface immobilization is also leading to enzyme structure rigidification, allowing them to endure mechanical stresses generated by a laminar water flow of 30 km h⁻¹, and this with no reduction of their enzymatic activity. Self‐defensive surface properties against microorganism's adhesion, preventing the enzyme alteration and improving the degradation performances, are obtained via surface saturation with Tween 20. The developed method is scaled up to high specific surface high‐density polyethy­lene biochips commonly used in water treatment, and shows self‐defensive abilities and particularly long lasting efficient degradation properties.     

Passive downdraught evaporative cooling: performance in a prototype house

The design and performance of a passive downdraught evaporative cooling (PDEC) system are reported. This is the first application of this technique for housing in Europe. The system was integrated within a house designed and built by University of Nottingham students for the 2010 Solar Decathlon Europe event in Madrid, Spain. Testing of the thermal performance of the house occurred for a limited period during June 2010. Performance data have demonstrated that the combination of a high-performance building envelope and PDEC provided comfortable conditions inside the house over a period of increasingly warm weather. Estimates of the cooling achieved, based on the measured results, were compared with the energy required by the system to derive an indicative range of coefficient of performance (CoP) values under varying ambient conditions. The results suggest that PDEC can deliver significant energy savings and achieve comfortable thermal conditions without the need for additional mechanical cooling. This technique may therefore have wider relevance to housing in central and southern Spain, and other hot, dry regions of the world.

Il est rendu compte de la conception et des performances d'un système de refroidissement passif évaporatif à courant d'air descendant (PDEC). Il s'agit de la première application de cette technique dans le domaine du logement en Europe. Le système a été intégré à une maison conçue et construite par des étudiants de l'Université de Nottingham pour la manifestation Solar Decathlon Europe 2010 qui s'est tenue à Madrid, en Espagne. Les données de performance ont démontré que la combinaison d'une enveloppe de bâtiment haute performance et d'un système PDEC ont assuré des conditions agréables à l'intérieur de la maison sur une période où le temps est devenu de plus en plus chaud. Les estimations quant au refroidissement obtenu, sur la base des résultats mesurés, ont été comparées à l'énergie exigée par le système de façon à déterminer une plage indicative des valeurs du coefficient de performance (CoP) dans différentes conditions ambiantes. Les résultats suggèrent que le PDEC peut assurer d'importantes économies d'énergie et créer des conditions thermiques agréables sans qu'il y ait besoin d'un refroidissement mécanique supplémentaire. Cette technique peut par conséquent présenter un intérêt plus large pour le logement en Espagne centrale et du sud, ainsi que dans les autres régions chaudes et sèches du monde.

Mots clés: performance des bâtiments, refroidissement, courant d'air descendant, évaporatif, logement, innovation, passif     

Diarylpropane‐1,3‐dione Derivatives as TetR‐Inducing Tetracycline Mimetics: Synthesis and Biological Investigations

Synthesis, biological investigations and molecular docking studies of nonantibiotic and nontetracyclic inducers that feature a minimal key motif of the natural lead tetracycline are presented. The diarylpropane‐1,3‐dione motif was identified as the minimal substructure responsible for TetR induction by tetracyclines. The first nontetracyclic surrogates of the natural tetracyclines displayed significant inducing effects for TetR(BD)S135L, whereby the chlorohydroxyphenyl‐substituted β‐diketone 31 displayed the highest activity. Interestingly, antibiotic activity could not be detected for 31 . Homology modeling based on the X‐ray structure of 7‐chlorotetracycline bound to TetR indicated analogous binding modes for the natural inducer and the synthetic diarylpropane‐1,3‐dione derivatives.     

一维非恒定流模型与卡尔曼滤波耦合的实时交替校正方法研究

本文从一维圣维南方程离散线性化后的差分方程组出发，结合河道水流计算的边界条件，分别以水位、流量及糙率为状态向量建立3种卡尔曼滤波状态空间方程，研发出河道水流计算与变量交替实时校正的耦合模型。与天然河道实测资料类型及系列长短各异的特点相匹配，模型中变量校正模式选择灵活，对每一种校正模式，依据边界条件的给定方式自动切换到相应的处理模块，程序为每一校正时刻、每一校正模块动态地创建相应维数的卡尔曼滤波器。基于环状河网的求解机制，实时交替校正模式被嵌入扩展到环状河网水动力学模型中，初步实现了环状河网水流计算与实时校正的联解。实例检验效果证明了分离变量校正思想的可行性及所建模型的合理性。     

The optimal group strategies method for matching subjective measurements

A method is proposed for matching subjective measurements in pair comparisons of multifactor alternatives by the use of expert optimal group strategies involving maximum likelihood principles. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 20–22, February, 2006.