Influence of chloride concentration on the formation of AOX in UV oxidative system

In this study, the effects of chloride ion concentration and pH on UV oxidation treatment were examined. Acetone and sodium dodecyl sulfate (ABS) were used as organic substances. The treatment efficiencies of these chemicals by UV/H(2)O(2) oxidation using a laboratory scale UV-free surface reactor (UV-FSR) with or without Cl(-) addition at different pH values was compared. Results of this study indicated that Cl(-) concentration and the chemical structure of the substances are more decisive than pH in the oxidation process. There was no AOX at the start of the experiments but as a result of oxidation a de novo synthesis of AOX was observed, and these AOX(de novo) compounds were destroyed during the treatment. Treatment was followed by TOC and AOX measurements. Approximately 98% and 95% TOC removal efficiencies were obtained for the treatment of acetone and ABS containing wastewaters, respectively.     

Antioxidative activity of green tea catechin extract compared with that of rosemary extract

This study compared the antioxidative activity of green tea catechin (GTC) extract with that of rosemary extract in canola oil, pork lard, and chicken fat. The GTC extract was obtained from jasmine and longjing green teas and mainly consisted of four epicatechin isomers including (−)epigallocatechin gallate (EGCG), (−)epigallocatechin (EGC), (−)epicatechin (EC), and (−)epicatechin gallate (ECG). The oxidation was conducted at 100 ± 2°C by monitoring oxygen uptake. The oxygen consumption test demonstrated that GTC extract was much more effective than the rosemary extract against lipid oxidation in canola oil, pork lard, and chicken fat under the conditions of the present study. Together with our previous study which showed that GTC extract was more protective than butylated hydroxytoluene as an antioxidant, these results suggest that GTC as a mixture of EGCG, EGC, EC, and ECG may serve as an antioxidant in processed foods.     

Political Risks: Analysis of Key Contract Clauses in China's BOT Project

The reforms introduced by the International Monetary Fund in Asia will bring about greater transparency in the economies and innovative approaches in procurement of contracts. China has taken new initiatives in build, operate, and transfer (BOT) infrastructure projects. It is, however, important to analyze and manage the unique or critical risks associated with China's BOT projects. This is especially so after new policies were introduced in late 1996 when the first state-approved BOT project, the U.S. $650,000,000 2 × 350 MW coal-fired Laibin B Power Plant (Laibin B), was awarded. These include the competitive tendering process and 100% foreign ownership of the operating company. An international survey on risk management of BOT projects in China was conducted to seek the views of practitioners. The overall objectives of the survey are (1) to identify the unique or critical risks associated with China's BOT projects; (2) to evaluate the effectiveness of measures for mitigating these risks; (3) to examine the key contract clauses used in Laibin B's concession agreement; and (4) to provide a risk management framework for investing in future BOT projects in China. This paper discusses the adequacy of key contract clauses in Laibin B's concession agreement related to the political and force majeure risks in China, from the perspective of foreign developers, lawyers, and lenders. The contract clauses discussed include changes in law, corruption, delay in approval, expropriation, and force majeure. Areas for further improvement in the clauses are suggested.     

Development of high‐pressure composite butt‐weld joints

There is currently a need to develop High‐pressure composite butt‐weld joints to meet the needs of deepwater activities. In this study, a tapered butt‐weld composite joint configuration is proposed. Finite element analysis was conducted to validate the proposed structural configuration through stress‐strain distribution analysis. Test samples were assembled using the hand lay‐up technique. The prepared specimens were hydro‐tested. The test results justified the proposed joint configurations. An approximate 35.7% increase in bursting pressure in the tapered butt‐weld composite joint was observed over currently used composite butt‐weld joints.     

西秦岭温泉一带斑岩型钼矿区地球化学异常特征及找矿前景分析

温泉钼矿是2000年在西秦岭发现的一个大型钼矿床,该钼矿床的发现结束了西秦岭成矿带无大型钼矿的观点,钼矿床产于温泉复式岩体二长花岗斑岩内外接触带及其裂隙系统中。通过对该区1:20万区域化探异常的研究,Mo、W、Cd、Bi、Ag与成矿有关的异常及亲酸性元素Be、Li、Sn、Th等元素的异常在复式岩体的晚期小岩体中发育,其异常的内带基本与晚期小岩体的范围一致,这些元素的异常是寻找该区斑岩型钼矿的直接指示元素。     

Noise properties of a bidirectional optical fiber transmission system using Raman amplifers

Abstract

Noise properties of a bidirectional optical fiber transmission system using Raman amplification are analyzed. Analytical expressions for both forward and backward amplified spontaneous emission (ASE) noise are established in terms of system parameters. The signal to ASE noise ratio (SNR) and the achievable repeater length are discussed. Based on the results, we find that there exist optimum pump and initial power levels for the maximum SNR and repeater spacing. The maximum system transmission length and accumulated ASE noise for a multiple‐amplifier system are calculated. A maximum system transmission length up to 5,000 km with 12 dB SNR is then predicted.     

Up-conversion of Er3＋/yb3＋ co-doped transparent glass-ceramics containing Ba2LaF7 nanocrystals

The up-conversion of Er3+/Yb3+co-doped transparent glass-ceramics 50SiO2-10AlF3-5TiO2-30BaF2-4LaF3-0.5ErF3-0.5YbF3 containing Ba2 LaF7 nanocrystals under the changing of heat treatment temperature and time were investigated.The Ba2 LaF7 nanocrystals precipitated from the glass matrix was confirmed by X-ray diffraction(XRD).The structural investigation carried out by XRD and transmission electron microscopy(TEM) evidenced the formation of cubic Ba2 LaF7 nanocrystals with crystal size of about 14 nm.Comparing with the samples before heat treatment,the high efficiency up-conversion emission of Er3+/Yb3+co-doped samples was observed in the glass-ceramics under 980 nm laser diode excitation.The increase in red emission intensity bands was stronger than the green bands when the crystal size increased.The mechanism for the up-conversion process in the glass-ceramics and the reasons for the increase of Er3+/Yb3+co-doped up-conversion intensity after heat treatment were discussed.     

Mechanical properties and fracture behavior of high-strength steels

Typical thicknesses of high-strength steels (HSS) sheets used in the car industry are inapplicable for standardized testing procedures. The aim of this study is to propose an appropriate methodology for testing and comparing of thin HSS sheets. Microstructures were observed by means of light and scanning electron microscopy. The modified Charpy impact tests and fracture toughness tests were used in order to compare the fracture properties of three different HSS sheets (Docol 1200 M, Multiphase 1200 and BTR 165). Ductile-to-brittle transition curves and tearing resistance (J − Δa) curves were measured. From the fracture toughness linked to the specimen thicknesses the value of fracture toughness K_Ic was estimated. Fractographic analysis of broken specimens has revealed that due to the fine microstructure of mixed ferrite-martensite fracture mechanism remains ductile even at low temperatures (down to −100°C). __________ Translated from Problemy Prochnosti, No. 1, pp. 155–158, January–February, 2008.