Highly size- and shape-controlled synthesis of silver nanoparticles via a templated Tollens reaction

A mild, facile one-step synthetic strategy for the preparation of size- and shape-controlled silver nanoparticles (AgNPs) is presented. The high degree of size- and shape-control of these AgNPs is achieved by the use of triazole sugar ligands scaffolded by a central resorcinol ether core. Both the triazoles and the resorcinol ether core mediate the nucleation, growth, and passivation phases of the preparation of AgNP in the presence of the Tollens reagent as the silver source. Kinetic and (1)H NMR titration data is presented describing the nature of the interactions between the Tollens reagent and these ligands.     

Spectroscopic studies of ligand exchange reactions in alkyl- and estertin PVC stabilizers

It has long been appreciated that mercaptoester/Cl exchange equilibria in mono- and dialkyltin mercaptoester/chlorides are important in understanding the stabilization of PVC by alkyltin mercaptoesters (1–3). More recently, IR studies have demonstrated the existence of similar equilibria in mixed mono-/dialkyltin systems; it has been suggested that these exchange reactions may be the source of synergism in the mixed mono-/dialkytin mercaptoester stabilizers (4). The ability to study these systems by IR and NMR methods is based upon the phenmenon of carbonyl to Sn coordination in these compounds and its sensitivity to molecular environment, principally the electronegativity of the tin atom. Our previous studies have now been extended to include estertin (β-carboalkoxyethyltin) mercaptoesters and mercaptoester/chlorides. In contrast to the simple alkyltin systems, the position of the respective mercaptoester/Cl exchange equilibria are dominated by carbonyl to Sn coordination from the ester group of the β-carboalkoxyethyl moiety. Based on the same phenomenon of carbonyl to tin coordination, the nature of alkyl- and estertin mercaptoesters containing alkyltin sulfides has been looked at to a very limited extent.     

Gheo‐shih: an ancient pre‐Columbian plaza

This paper describes the configuration and cultural context of the oldest known designed space in central America, Gheo‐Shih, dating from 5,000 – 4,000 BC. This site may have been a ceremonial space, being employed in a similar fashion to ceremonial spaces of Native American cultures from the North American Great Basin. It contains physical features that set precedents and are similar to the geomantic features of later nearby Mesoamerican cultures.     

景观规划：美国景观设计透视

景观规划是景观设计师所感兴趣的课题,他们致力于研究与场地设计相关的事宜和环境。美国景观规划的历史可谓源远流长。2007年秋,密歇根州立大学景观设计师柏利博士分别在中国五所著名高校做了25小时的景观规划报告。他在报告中阐述了美国景观规划的发展历程、传统的景观叠加方法、参数化方法、统计模式以及景观规划的未来发展方向。其中的一篇报告还涉及到景观美感和规划的问题。本文综述其系列报告的部分内容。     

明孝陵禁约碑注译及景观诠释简

规划师、设计师和学者们在对在风景游览过程中规范人们行为的规章很感兴趣。在古代,明孝陵禁约碑的碑文中早已有对陵墓景观管理方面的相关条例。通过对其碑文的注译,探讨碑文的内在含义,研究其出现的时代背景,深入探讨中国文化对于中国人环境态度形成的影响,从而加深对于陵墓景观管理历史的学习,讨论其对于当今文化遗产景观保护与管理指导意义。     

Clinical trials of antibacterial agents: a practical guide to design and analysis. Statisticians in the Pharmaceutical Industry Working Party

Guidelines on the conduct of clinical trials of antibacterial agents produced by the US Food and Drug Administration, the British Society for Antimicrobial Chemotherapy, the Infectious Diseases Society of America and a European Working Party have been reviewed. Although very informative, these guidelines provide limited practical guidance on the design and statistical aspects of phase III studies of antimicrobial agents. This paper describes the differences between antibacterial trials and clinical studies in other therapeutic areas with regard to subjective endpoints, dual clinical and bacteriological endpoints, frequent protocol violations and difficulty of using placebo controls. The importance of a detailed protocol and planned analysis strategy is emphasized. The choice of comparator agents, practical issues with the blinding of trial materials and the documentation of patients excluded from study entry are discussed. The use of different patient groups and different endpoints in analyses are described. The principles of equivalence and their application to trials of antibacterial agents are discussed, together with an approach to calculating sample size. A variety of statistical analyses of results are compared for different situations indicating some of the problems that can arise. Different methods of presentation of study data are included with emphasis on regulatory submissions rather than scientific publications. Some graphical presentations are recommended and issues regarding data across different studies are discussed.     

Nucleic acid and nucleotide-mediated synthesis of inorganic nanoparticles

Since the advent of practical methods for achieving DNA metallization, the use of nucleic acids as templates for the synthesis of inorganic nanoparticles (NPs) has become an active area of study. It is now widely recognized that nucleic acids have the ability to control the growth and morphology of inorganic NPs. These biopolymers are particularly appealing as templating agents as their ease of synthesis in conjunction with the possibility of screening nucleotide composition, sequence and length, provides the means to modulate the physico-chemical properties of the resulting NPs. Several synthetic procedures leading to NPs with interesting photophysical properties as well as studies aimed at rationalizing the mechanism of nucleic acid-templated NP synthesis are now being reported. This progress article will outline the current understanding of the nucleic acid-templated process and provides an up to date reference in this nascent field.     

RNA chiropractics

BACKGROUND AND OBJECTIVE: With the increasing use of laser resurfacing, concerns have arisen about the biological hazards associated with the procedure. This study analyzed the potential bacterial and viral exposure to operating room personnel as a result of the laser smoke plume in CO2 laser resurfacing. STUDY DESIGN/MATERIALS AND METHODS: Thirteen consecutive patients underwent CO2 laser resurfacing. A HEPA filter in the smoke evacuator was used to collect specimens of the laser plume smoke for cultures. The study was controlled by a second filter exposed to room air. RESULTS: The 13 patients each had one bacterial, one viral, and one control culture (total, 39 specimens). In the control group, none of the 13 specimens had any growth. No viral growth has been found to date. Of 13 bacterial cultures, 5 resulted in growth of coagulase-negative Staphylococcus. Of these five positive specimens, one also had growth of Corynebacterium and one had growth of Neisseria. CONCLUSION: The potential exists for operating personnel to be exposed to viable bacteria during laser resurfacing.     

Deoxynivalenol exposure assessment in a cohort of pregnant women from Bradford, UK

Deoxynivalenol (DON) is a ubiquitous contaminant of cereal crops in temperate regions of the world. It causes growth faltering and immune suppression in animals. Limited information is available on DON exposure in UK subpopulations. The objective of this study was to provide DON exposure assessment in a subset of pregnant women scheduled for an elective caesarean in a large multi-ethnic mother/infant birth cohort from Bradford, UK. Women aged 16-44 years (n = 85) provided a urine sample for DON analysis in the last trimester of pregnancy, and concurrently completed a food-frequency questionnaire (FFQ). The urinary DON biomarker was detected in all measured samples (geometric mean (GM)?= 10.3 ng DON mg(-1) creatinine, range = 0.5-116.7 ng mg(-1)). Levels were higher in women classified as South Asian in origin (GM: 15.2 ng mg(-1); 95% CI = 10.7-21.5 ng mg(-1)) compared with non-South Asians (GM = 8.6 ng mg(-1); 95% CI = 6.6-11.8 ng mg(-1)), p = 0.02). Estimated DON intake from FFQ data and typical levels of DON contamination of food suggest that this was mainly due to higher levels of exposure from bread, particularly daily intake of DON from chapattis in South Asians (estimated mean = 2.4 μg day(-1); 95% CI = 1.2, 3.7 μg day(-1)) compared with non-South Asians (estimated mean = 0.2 μg day(-1); 95% CI = 0-0.4 μg day(-1)), p < 0.001. This is the first biomarker demonstration of DON exposure in pregnant women, and several urinary DON levels were the highest ever recorded in any study. A larger survey within this birth cohort is warranted to investigate any potential risk to mothers and their babies, from DON exposure during pregnancy.