Occurrence and fate of linear and branched alkylbenzenesulfonates and their metabolites in surface waters in the Philippines

Laguna de Bay in the Philippines is one of the largest freshwater lakes in Asia and is considered a primary source of drinking water, but also receives daily discharges of effluent from both domestic and industrial activities. Branched alkylbenzenesulfonates (ABS), which were banned in Europe and withdrawn from the market in the U.S. since the mid-1960s, but not in Southeast Asia, and linear alkylbenzenesulfonates (LAS) are anionic surfactants used in detergent formulations and are therefore main components of effluent discharges. The presence of both LAS and ABS in several water streams in the catchment area of Laguna de Bay was determined using liquid chromatography-mass spectrometry (LC-MS). The concentration levels of LAS (1.2-73 and 2.2-102 microg l(-1)) and ABS (1.1-75 and 1-66 microg l(-1)) in some tributaries of Laguna de Bay and its outlet (Pasig River) to Manila Bay were assessed in December 1999 and March 2000, respectively. The LAS/ABS ratio was calculated as an indication of the extent of the distribution and fate of these surfactants in the surface water. The nearer the location to the metropolitan area of Manila, the higher the levels of LAS and ABS detected in the waters. Moreover, the extent of biodegradation was investigated by monitoring their alkyl homologue distribution and the presence of sulfophenylcarboxylate (SPC) metabolites. Similarly, differences in the levels of SPC and the homologues were apparent at the different sampling points. Presumably, even the quite recalcitrant ABS form SPCs under the conditions present in Southeast Asia. Since wastewater treatment facilities are not well established in developing countries like the Philippines, the call for the use of environmentally friendly chemicals is of even higher significance.     

Well-shaped fibre tips by pulling with a foil heater

The length of the molten zone determines the length of pulled optical fibre tips. Tips produced by laser or filament heating are rather lengthy. By using a foil heater the taper length can be shortened and cone angles in the order of 30° can reproducibly be obtained. For varying the drawing force there is an optimum temperature range where the taper shape is monotonic for the whole tip. The tip end diameter is well below 100 nm for optimized pulling conditions.     

Double-pulse technique as an electrochemical tool for controlling the preparation of metallic nanoparticles

Various structures of silver nanoparticles were generated by means of the double-pulse technique. The interaction of the pulse parameters was modeled to demonstrate that the electrodeposition of nanoparticles can be variably controlled. The results derived showed how to create nanoparticle structures with respect to size, density and monodispersity according to the application goal.     

Virtual Reality in Metal Forming

A tool which is being used more and more frequently in companies is Virtual Reality (VR). It enables a realistic three‐dimensional representation of models and data which even non‐experts can follow easily. In a project carried out by SMS Demag AG in collaboration with the Technical University of Aachen (RWTH), VR is used to show how individual components are merged to form an overall image of a CSP plant. Starting from the mere visualization of the CSP plant, information is integrated in a hierarchical structure which extends into the microstructural level. This hierarchy is shown as an example at certain locations of the CSP plant but can be expanded as required, both in terms of depth (several levels) as well as along the production line (incorporating further process steps). Further developments are starting to establish direct links between the simulation programs and VR. With the improvement in computer performance and the resulting real‐time ability of the calculations, it will become possible to influence the calculation and also to directly see the results of the change.     

带钢生产的技术革命

带钢生产过程的技术性和经济性 直到八十年代末,带钢生产技术水平的发展,基本上是处于发展“单打一”工序的过程。比如铸钢过程,它只涉及连续铸造技术的发明、发展和最优化。而热轧和冷轧,则加入控制板型和平直度的压下系统,增加了生产流程的灵活性和改善了产品质量。