壳聚糖的抗菌性能研究

本文考察了不同分子量壳聚糖对大肠杆菌和金黄色葡萄球菌的抗菌抑菌性能 ,初步找出了壳聚糖分子量和浓度对抗菌抑菌作用的影响 ,提出了壳聚糖的抗菌机理。研究发现 :分子量在 3 0万以下时 ,壳聚糖对金黄色葡萄球菌的抗菌作用随分子量减小而逐渐减弱 ;对大肠杆菌分子量越小 ,抗菌作用越明显。     

Woven Surface and Form

The Advanced Geometry Unit (AGU) at Arup, founded by Cecil Balmond and Charles Walker, has become synonymous with a highly mathematical, topological approach to architecture. It has, however, collaborated on some of the most exciting experimental fabric structures of recent years, including Anish Kapoor's Marsyas at Tate Modern and Rem Koolhaas's Cosmic Egg at the Serpentine Gallery. Here, the unit's Tristan Simmonds, Martin Self and Daniel Bosia describe how the AGU has progressed research into textile techniques that encompass tailored biomorphic forms alongside knot diagrams. Copyright © 2006 John Wiley & Sons, Ltd.     

St15钢板冲裂成因分析

在利用St15钢板生产表壳过程中有少部分原料被冲裂。采用日本扫描电子显微镜、英国牛津公司的能谱仪和EBSD、光学显微镜、拉力实验机检测结果表明,组织不均匀、{111}织构较漫散是冲裂的主要成因。     

Relationships among total recoverable and reactive metals and metalloid in St. Lawrence River sediment: bioaccumulation by chironomids and implications for ecological risk assessment

The availability and bioaccumulation of metals and metalloids, and the geochemical interactions among them, are essential to developing an ecological risk assessment (ERA) framework and determining threshold concentrations for these elements. The purpose of this study was to explore the relationships among total recoverable and reactive metals and metalloid in sediment and their bioaccumulation by chironomids. In the fall of 2004 and 2005, 58 stations located in the three fluvial lakes of the St. Lawrence River and its largest harbour area in Montreal, Canada, were sampled. Nine total recoverable and reactive metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and one metalloid (As) were measured in whole sediment using two extraction methods: HCl/HNO(3) and HCl 1N, respectively. The bioaccumulation of six metals (Cd, Cr, Cu, Ni, Pb and Zn) and As by chironomids was evaluated in a subset of 22 stations. Strong collinearities were observed between some total recoverable or reactive metal concentrations in sediment; two principal clusters, including collinear metals, were obtained. The first one included metals of mainly geological origin (Al, Cr, Fe, Mn, Ni), while the second one included As, Cd, Cu, Pb and Zn, which likely derive mainly from point sources of anthropogenic contamination. Each element also showed strong collinearity between their total recoverable and reactive forms (0.65< or =r < or =0.97). We can conclude that both chemical forms are equivalent for use in statistical models needed to explain biological responses and also in screening risk assessment. However, these relationships are not always proportional. Lower availability percentages were observed for Cd, Cu and Zn in the highly mixed-contaminated area of the Montreal Harbour, even though concentrations in sediment were higher. We observed a significant correlation (0.50< or =r < or =0.56) between concentrations in chironomids and concentrations of both total recoverable and reactive Cr and Pb in sediment. Arsenic was an exception, with accumulation by chironomids being highly related to reactive sediment concentrations. Finally, we observed variable influences of explanatory factors (e.g. sediment grain size, Al, Fe, Mn, S, TOC), depending on which metal or metalloid was being predicted in chironomids. In this context, it is difficult to choose a universal predictive method to explain the bioaccumulation of specific metals, and more research is still needed into normalization procedures that consider a combination of explanatory factors.     

Destination choice for relocating firms: A discrete choice model for the St. Gallen region,Switzerland*

Because of interdependence between resident population (e.g., as customers or manpower) and economic activities (e.g., shops or services), relocating firms' destination choice plays an important role in comprehensive land use models. However, due to a lack of data at the micro level enabling the estimation of discrete choice models, little research exists on this topic. In this paper, data from commercial registers of three Swiss cantons, St. Gallen, Appenzell Ausserrhoden, and Appenzell Innerrhoden, were analysed. This dataset provides information on more than 54,000 firms and autonomous plants from 1991 to 2006. Variables such as local taxes, governmental business friendliness, and accessibilities have been tested in a nested logit (NL) model for different business sectors. The results show that distance, local taxes, and cantonal business development strongly influence relocating firms' destination choice. Furthermore, significant differences between sectors can be identified. For instance, residents with graduate degrees have a significant and high impact on business services, but a minimal effect on businesses in wholesale trade and personal services. Debido a la interdependencia entre la población residente (p.ej. como clientes o mano de obra) y las actividades económicas (p.ej. comercios o servicios), la elección del destino en el traslado de una empresa juega un papel importante en modelos exhaustivos de uso del suelo. Sin embargo, debido a una falta de datos a nivel microeconómico que permitiesen estimar modelos de elección discreta, apenas existen estudios sobre este tema. En este artículo se han analizado datos de registros comerciales de tres cantones suizos: San Galo (St. Gallen), Appenzell Rodas Exteriores (Ausserrhoden), y Appenzell Rodas Interiores (Innerrhoden). Este conjunto de datos proporciona información acerca de más de 54.000 empresas y factorías autónomas desde 1991 a 2006. Se ha empleado un modelo logit anidado (nested logit, NL) para diferentes sectores empresariales, utilizando variables tales como impuestos locales, grado de benevolencia gubernamental con las empresas, y accesibilidades. Los resultados muestran que la distancia, los impuestos locales, y el desarrollo empresarial cantonal influyen poderosamente en la elección del destino en el traslado de una empresa. Adicionalmente, es posible identificar diferencias significativas entre sectores. Por ejemplo, los residentes con licenciaturas tienen un elevado y significativo impacto en los servicios empresariales, pero un efecto mínimo en empresas de comercio al por mayor y de servicios a individuos.      

Surrealism and Architectural Atmosphere

The concept of atmosphere in present architectural theory has many points of convergence with the insights of 20th-century Surrealism. Alberto Pérez-Gómez – Saidye Rosner Bronfman Professor of the History of Architecture at McGill University in Montreal – here examines themes including desire, poetics, musical affinities and the risks of stylistic imitation, with reference to writers from André Breton to Octavio Paz and from Edmund Husserl to Maurice Merleau-Ponty.     

Built Conservation and the Unfinished Fabrics of Time

Differentiating between the static impulse to preserve and the more open-ended and imaginative process of conservation, Federica Goffi presents a building as ‘a fabric that, even when complete, is unfinished and open to change’. Associate Professor and Associate Director of Graduate Programs at the Azrieli School of Architecture and Urbanism at Carleton University in Ottawa, Goffi has written widely on the topic of time, particularly taking St Peter's in the Vatican by way of example.