The metal injection molding process comes of age

Metal injection molding is a new commercial process for producing complex component parts from steels and other ferrous alloys. The process combines the shape-making capability of plastic injection molding with high-temperature sintering technology to produce complex, high density metal parts with outstanding properties. The savings in production costs can be substantial over investment casting or expensive machining operations.     

Towards processible poly(pyrrol-2-ylsquaraines)

Summary In an attempt to produce a processible poly(pyrrol-2-ylsquaraine) by forming a copolymer of poly(pyrrol-2-ylsquaraine) with polymethylmethacrylate, two synthetic routes were utilised. The first included forming the polysquaraine and then polymerising the attached methacrylate groups to form the desired product and the second proceeded via the preformed methacrylate polymer, containing N-alkylpyrrole side chains, which was then condensed with squaric acid. Difficulties arose in the first route when the polysquaraine product was found to be insoluble, hence preventing any further polymerisation but partial solubility during the second procedure did allow bissquaraines to be formed and, as a consequence, the resultant product exhibited fluorescent properties. Yet the desired processible poly(pyrrol-2-ylsquaraine) was not achieved. Received: 30 October 1997/Revised version: 22 January 1998/Accepted: 23 January 1998     

Chemical exposures from upholstered furniture with various flame retardant technologies

Upholstered furniture is often manufactured with polyurethane foam (PUF) containing flame retardants (FRs) to prevent the risk of a fire and/or to meet flammability regulations, however, exposure to certain FRs and other chemicals have been linked to adverse health effects. This study developed a new methodology for evaluating volatile organic compound (VOC) and FR exposures to users of upholstered furniture by simulating use of a chair in a controlled exposure chamber and assessing the health significance of measured chemical exposure. Chairs with different fire-resistant technologies were evaluated for VOC and FR exposures via inhalation, ingestion, and dermal contact exposure routes. Data show that VOC exposure levels are lower than threshold levels defined by the US and global indoor air criteria. Brominated FRs were not detected from the studied chairs. The organophosphate FRs added to PUF were released into the surrounding air (0.4 ng/m³) and as dust (16 ng/m²). Exposure modeling showed that adults are exposed to FRs released from upholstered furniture mostly by dermal contact and children are exposed via dermal and ingestion exposure. Children are most susceptible to FR exposure/dose (2 times higher average daily dose than adults) due to their frequent hand to mouth contact.     

Mapping slums in a historic city: representing working class communities in Edwardian Norwich

Drawing on a range of sources, this article addresses the way in which various groups set about mapping the slums of Edwardian Norwich to bring understanding and order to the disordered world of the city's 750 courts and yards. It focuses on the social scientific investigations incorporated in the reports of the Medical Officer of Health; the evidence of social investigators; the findings of charitable bodies and the writings of local journalists, whether addressing the slum issue directly or reporting news stories set in slum areas. It shows how these individuals and groups identified, categorized and interpreted the slums and their dwellers and, by making the unknown known, encouraged a more vigorous intervention by the local state in the lives of the poor. It demonstrates the way in which these concerns and ideals came together in the moral panic which followed the Norwich Flood of August 1912, an event which revealed the dreadful state of the inner-city housing to a city-wide audience and culminated in the City's first public housing scheme. It shows how the impetus to demolish slums and build public housing on the outskirts of the city was conditioned by both the application of medical criteria and traditional moral constructions of the characters of slum dwellers.     

美国宾城大学阿帕拉契学生中心

宾城大学阿帕拉契学生中心打开了从已有院区到山顶新的居住区的大门。学生中心的餐厅充分地利用丘陵地势设计,“浮”于基地之上。这不仅提供了向下面谷地开阔的视野,而且创造了包括广场、咖啡屋、露天剧场和石园在内的下层聚会空间。此外,一部巨大的楼梯从餐厅延伸下来,使餐厅成为新居住区的标志性入口。建筑内外的设计都旨在促进学生之间的社交活动。     

The viscoplastic properties of crude oil-water interfaces

The breaking of water-in-crude oil emulsions is a major challenge in the conventional petroleum industry, while oil-in-water emulsions present similar issues in commercial oilsands extraction processes. The stability of these emulsions can be attributed to complex rheological properties of the crude oil-water interface. Novel micromechanical techniques are developed that allow direct measurements of interfacial behaviour of emulsion drops. In these techniques, individual emulsion drops are elongated using micropipettes, where one micropipette is shaped into a cantilever for force measurements. As such, the surface behaviour of a drop is recorded in stress-strain experiments. In an alternative technique, the extended drop is released from a micropipette, and its natural, tension-driven relaxation is observed.The surface behaviour of bitumen (a heavy crude oil) emulsion drops in aqueous environments, that include dissolved calcium ions and suspended montmorillonite clays, is studied. The plasticity and other surface properties of these bitumen drops are discussed. A simple, lumped-parameter model is developed to describe the recovery of a bitumen drops to their final non-spherical shapes.     

Cathode performance: The influence of design, operations, and operating conditions

There have been tremendous advances in the materials, knowledge, design, and construction of cathodes; however, widelydivergent cell operations and operating conditions present a challenge for selecting the right materials and lining design for good cell life. Cathode wear is frequently becoming the life-determining step, and, although there are questions still to be answered, it is probable that particulate detachment (physical wear) plays an important role in parallel with carbide dissolution. If wear cannot be controlled by smart design and operations, coating technology may offer benefits for extending the life of cathode linings by reducing or eliminating wear. Thus, it would also enable softer graphitic materials to be utilized more readily, and this advantage will become more important if the trend toward higher current density continues.