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971.
Triclosan (TCS), an antimicrobial agent, is an emerging and persistent environmental pollutant that is often found as a contaminant in surface waters and sediments; hence, knowledge of its degradability is important. In this study we investigated laccase-mediated TCS transformation and detoxification, using laccase (from the fungus Ganoderma lucidum) in the presence and absence of redox mediators. Transformation products were identified using HPLC, ESI-MS and GC-MS, and transformation mechanisms were proposed. In the absence of redox mediator, 56.5% TCS removal was observed within 24 h, concomitant with formation of new products with molecular weights greater than that of TCS. These products were dimers and trimers of TCS, as confirmed by ESI-MS analysis. Among the various mediators tested, 1-hydroxybenzotriazole (HBT) and syringaldehyde (SYD) significantly enhanced TCS transformation (∼90%). The presence of these mediators resulted in products with lower molecular weights than TCS, including 2,4-dichlorophenol (2,4-DCP; confirmed by GC-MS) and dechlorinated forms of 2,4-DCP. When SYD was used as the mediator, dechlorination resulted in 2-chlorohydroquinone (2-CHQ). Bacterial growth inhibition studies revealed that laccase-mediated transformation of TCS effectively decreased its toxicity, with ultimate conversion to less toxic or nontoxic products. Our results confirmed the involvement of two mechanisms of laccase-catalyzed TCS removal: (i) oligomerization in the absence of redox mediators, and (ii) ether bond cleavage followed by dechlorination in the presence of redox mediators. These results suggest that laccase in combination with natural redox mediator systems may be a useful strategy for the detoxification and elimination of TCS from aqueous systems. 相似文献
972.
Jong-Yul Kim Kyeong-Jun MunHyung-Su Kim June Ho Park 《International Journal of Electrical Power & Energy Systems》2011,33(8):1457-1461
In recent studies, PSO algorithm is applied to solve OPF problem. However, population based optimization method requires higher computing time to find optimal point. This shortcoming is overcome by a straightforward parallelization of PSO algorithm. The developed parallel PSO algorithm is implemented on a PC-cluster system with 8 Intel Pentium IV 2 GHz processors. The proposed approach has been tested on the test systems. The results showed that computing time of parallelized PSO algorithm can be reduced by parallel processing without losing the quality of solution. 相似文献
973.
Kim J.W. Shen D.Y. Sahu J.K. Clarkson W.A. 《IEEE journal of selected topics in quantum electronics》2009,15(2):361-371
Hybrid fiber-laser-pumped solid-state lasers exploit high-power cladding-pumped fiber lasers for direct (in-band) pumping of a crystal-based solid-state laser to reduce heating in the laser crystal, and hence allow scaling to higher power in both continuous-wave (CW) and pulsed modes of operation. In this paper, we briefly review the attractions of the hybrid laser approach for generation of output in the ~ 1.6 mum wavelength regime and consider the main design considerations for efficient operation of hybrid lasers based on Er:YAG in both CW and pulsed modes of operation. Examples of hybrid Er:YAG lasers, pumped by Er,Yb codoped fiber lasers at 1532 nm, with CW output powers up to 60 W at 1645 nm and 31 W at 1617 nm and slope efficiencies of 80% and 47% with respect to incident pump power, respectively, are described. In Q-switched mode of operation, pulse energies up to 30.5 mJ were obtained, limited by coating damage. Finally, the prospects for further increase in output power and improvement in overall performance in CW and Q-switched modes of operation will be discussed. 相似文献
974.
Yi-Kai Juan Jun Ha Kim Kathy Roper Daniel Castro-Lacouture 《Automation in Construction》2009,18(4):394-401
Refurbishment work involves improvement, upgrading, renovation, retrofit, and repair of existing housing. With limited land usage and being aware of sustainability, the refurbishment market has faced increasing needs worldwide. During the long life cycle period of housing, most residents are undoubtedly faced with refurbishment requirements. However, it is not easy to make assessment and refurbishment related decisions due to the lack of knowledge and experience. This study presents Genetic algorithm-based on-line decision support system (DSS) to help residents easily conduct the housing condition assessment and offers optimal refurbishment actions considering the trade-off between cost and quality. Two refurbishment models are developed to explore the relationship among the life cycle cost, restoration cost and improved quality. The result reveals the proposed DSS solves the problems arising from asymmetric information and conflicting interests between residents and contractors, as well as improves traditional housing condition assessment to be more effective and efficient. 相似文献
975.
Nanotube morphology changes in Ti-Zr alloys as Zr content increases have been investigated. Ti-Zr (10, 20, 30 and 40 wt.%) alloys were prepared by arc melting and heat treated for 24 h at 1000 °C in an argon atmosphere. TiO2 nanotubes were formed on the Ti-Zr alloys by anodization in H3PO4 containing 0.5 wt.% NaF. Electrochemical experiments were performed using a conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. Samples were embedded in epoxy resin, leaving an area of 10 mm2 exposed to the electrolyte. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. Microstructures of the alloys were examined by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The Ti-Zr alloy microstructures observed by OM and FE-SEM changed from a lamellar structure to a needle-like structure with increasing Zr content. The microstructures also changed from β phase to increasing amounts of α phase as the Zr content increased. The number of large nanotubes formed by anodization decreased, and the number of small nanotubes increased, as the Zr content increased. The mean inner diameter ranged from approximately 150 to 200 nm with a tube-wall thickness of about 20 nm. The interspace between the nanotubes was approximately 60, 70, 100 and 130 nm for Zr contents of 10, 20, 30 and 40 wt.%, respectively. 相似文献
976.
Small scale models have been frequently used to experimentally investigate the seismic performance of structures because capacities of testing facilities are limited and because they are more economically viable. However, not enough studies have been carried out on the development of similitude laws for accurately analogizing prototype structures with small scale models. Furthermore, conventional similitude requirements based on geometry may not be suitable in the inelastic range. When a small scale model of a prototype reinforced concrete structure is fabricated from a similar material to the prototype, an added mass would generally be required due to the volumetric variation, while the scale factor, as a ratio of the scale model to the prototype, cannot be sufficiently reduced due to the limitation of aggregate size. As an alternative, for small scale models it is desirable to use materials that are dissimilar to those of the prototype. Thus, a modified similitude law can be derived that depends on the geometric scale factor, equivalent modulus ratio and peak strain ratio. In this study, compressive strength tests were carried out to analyze the equivalent modulus ratio of micro-concrete to normal-concrete. The equivalent modulus ratios could then be divided into multi phases of strain level, which are basically dependent on the peak strain level at ultimate strength. An algorithm adaptable to the pseudodynamic test was therefore developed that considers an equivalent multi-phase similitude law based entirely on strain levels. Prior to carrying out the physical experiments, a numerical simulation was performed by idealizing the designed specimens to a single degree of freedom system with a bilinear model, and the pseudodynamic testing algorithm was numerically verified from seismic responses. A prototype and a 1/5 scale model of reinforced concrete columns as a test specimen was designed and fabricated based on the equivalent modulus ratios already defined. As a preliminary test, quasi-static tests on test specimens were carried out and their experimental results were compared using the constant and variable modulus ratios. Furthermore, in the pseudodynamic test on small scale models, it was verified that the modified pseudodynamic testing algorithm that considers the developed equivalent multi-phase similitude law may offer better simulation of the prototype structures than the conventional pseudodynamic testing algorithm. Therefore, it is found that the equivalent multi-phase similitude law would be applicable to the pseudodynamic test on small scale models. 相似文献
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