Coumarin-containing hybrids and their antibacterial activities

Infections caused by Gram-positive and -negative bacteria are one of the foremost causes of morbidity and mortality globally. Antibiotics are the mainstay of therapy for bacterial infections, but the emergence and wide spread of drug-resistant pathogens have already become a huge issue for public healthcare systems. The coumarin moiety, which is ubiquitous in nature, could bind to the B subunit of DNA gyrase in bacteria and inhibit DNA supercoiling by blocking the ATPase activity; hence, coumarin derivatives possess potential antibacterial activity. Several coumarin-containing hybrids such as coumermycin A1, clorobiocin, and novobiocin have already been used in clinical practice for the treatment of various bacterial infections; thus, it is conceivable that hybridization of the coumarin moiety with other antibacterial pharmacophores may provide opportunities for the development of novel antibiotics. This review outlines the advances in coumarin-containing hybrids with antibacterial potential in the recent 5 years and the structure–activity relationships are also discussed.     

Case for diagnosis. Single-digit clubbing

A 58-year-old female patient presented with a single-digit clubbing on the second finger of her right hand two years previously. After investigation with imaging and incisional biopsy, superficial acral fibromyxoma was diagnosed. A brief review on single-digit clubbing and its causes is presented, focusing on superficial acral fibromyxoma.     

强迫症团体认知行为治疗与药物治疗的随机对照研究

目的分析团体认知行为治疗(group cognitive-behavioral therapy,GCBT)对强迫症患者的疗效。方法本研究采用随机对照试验设计,与常规抗强迫药物治疗做对照。将符合入组标准的94例未用药强迫症患者,采用Excel软件中的RAND函数产生随机数字表形成随机分组序列的简单随机分组法,随机分为GCBT组(47例)和药物治疗组(47例)。经12周的结构化GCBT治疗和常规抗强迫药物治疗,采用t检验、卡方检验和方差分析比较2组间Y-BOCS、HAMA14和HAMD24平均减分率和减分值的差异。结果(1)2组基线Y-BOCS及HAMA14评分差异无统计学意义(t=0.281,P=0.779;t=0.795,P=0.429),但GCBT组HAMD24评分显著低于药物治疗组(t=2.316,P<0.05)。2组各有16例患者退出治疗,总脱落率为34%(32/94)。(2)12周治疗结束时,2组患者的Y-BOCS评分较基线显著降低,GCBT组和药物治疗组治疗前后Y-BOCS平均减分率[(37.0±27.4)%比(45.5±22.9)%]和平均减分值[(9.0±6.3)分比(11.0±5.8)分]比较差异无统计学意义[F(1,62)=0.069,P=0.794;F(1,62)=0.001,P=0.975]。GCBT组和药物治疗组的有效率和治愈率差异无统计学意义(χ^2=1.653,P=0.199;χ^2=0.088,P=0.767)。(3)GCBT组HAMA14减分率和减分值与药物治疗组治疗前后比较差异无统计学意义(t=-0.922,P=0.362;t=1.082,P=0.286)。(4)GCBT组HAMD24减分率与药物治疗组治疗前后比较差异无统计学意义,但药物治疗组HAMD24减分值显著高于GCBT组(t=2.239,P=0.029)。结论GCBT与常规抗强迫药物治疗强迫症患者的强迫和焦虑症状的疗效相当,常规药物治疗对抑郁症状的疗效优于GCBT。     

适应性回归分析(Ⅲ)——构建具有混合结构的回归模型

本文目的是通过两个实例介绍适应性回归样条算法对具有混杂结构的数据集进行回归建模的实践。当一个数据集包含多个不同的回归模型时,只要给定分类变量的具体取值,SAS中的"ADAPTIVEREG过程"可以比较准确地发掘出其内在规律,并以图形方式呈现模型对资料的拟合效果,还能呈现由"基函数"及其组合所构造出的"回归模型"。图形呈现的结果确实可以给分析者提供一些有价值的"分析线索"或"积极暗示",缩小"探索性研究的空间"。     

基于DC元数据的资源统一描述策略探讨

不同类型信息资源、不同信息应用行业,有着众多不同的元数据标准或应用规范。寻求一种通用的、兼容多种类型信息资源和应用需求的资源统一描述方案,既能降低资源描述与管理成本,又能消除跨系统、跨资源类型的数据交换与信息整合障碍。本文基于都柏林核心元数据(Dublin Core Metadata,DC元数据)的理念,从元数据的编码实现着手,探讨了一种资源统一描述方案的设计策略,包括描述元素的核心化、可修饰或可限定策略,元数据结构化与可伸缩化策略,资源描述对象单一化策略。     

Microstructure and Interfacial Reactions of Resistance Brazed Lap Joints between TC4 Titanium Alloy and 304 Stainless Steel Using Metal Powder Interlayers

In the brazing joint between titanium alloy and stainless steel, a lot of Fe-Ti intermetallic compounds (IMCs) can be easily formed to make joints crack. A lap resistance brazing process with metal powder layers on both sides of the filler metal was used to solve this problem. The microstructure and metallurgical behavior of joints was studied through comparative experiments. The result showed that Nb, V and Cr powders and the solder reacted with the base material to form a new phase, which replaced the Ti-Fe brittle phase in the joint. At the same time, metal powder clusters hindered the diffusion of Ti and Fe elements and improved the distribution of new phases. The established atomic reaction model revealed the metallurgical behavior and formation mechanism of the joints. Therefore, the intervening position of the metal powder layer and the multi-reaction zone structure are the main reasons the shear strength of joints is improved.