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A new FAGE setup has recently been built at the University of Lille, France. It permits the quantification of OH and HO2 in the atmosphere with a detection limit of 3×105 molecules/(cm3·min) for OH and 1×106 molecules/(cm5·min) for HO2. Its coupling to a photolysis cell enables the measurement of the total reactivity of the hydroxyl radical in ambient air and kinetic studies in laboratory. Two configurations have been considered: one with the photolysis cell at 90° to the FAGE nozzle, the other on line with the FAGE nozzle. The two configurations have been tested and validated by measuring the well known rate constants of OH with CH4, C3H8 and CO. The advantages and drawbacks of each configuration have been evaluated. The “on line” configuration limits losses and permits measurements over a larger reactivity range but is affected by OH formation from the laser beam striking the FAGE nozzle, thus limiting the ability to carry out energy dependence studies which can, in contrast, be successfully performed in the 90° configuration. 相似文献
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William Whipple 《Journal of the American Water Resources Association》1973,9(4):639-646
Water pollution control by effluent treatment becomes increasingly expensive as the degree of treatment is increased. As has previously been demonstrated, instream aeration provides an economical alternative for the higher degrees of treatment. For large, deep, navigable rivers, another alternative may be still more economical, namely, mobile oxygenating craft, using fine bubble diffusers. The propellors in the craft plus its mobility would give important advantages in dispersing the oxygenated water; and one craft could replace a multiplicity of static aeration sites. 相似文献
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Summary Feeding by the homopteranPsylla pyricola on leaves of pear trees induces the production of volatile compounds, such as (E,E)--farnesene and methyl-salicylate, as well as the production of polyphenols. The inference on induction is based on GC-MS and HPLC chromatograms from the same samples ofPsylla infested leaves, leaves from the same pear tree beforePsylla infestation and uninfested leaves from other pear trees.Psylla infestation greatly enhanced the production of volatiles ((E,E)--farnesene, methyl-salicylate and others) and triggered the production of new polyphenols, characterized by much longer retention times.However, the responses to infestation depend critically on leaf age (defined by leaf distance to apex). With respect to the leaf volatiles it appears that infested, old leaves produce fewer compounds and lower amounts of the volatiles than infested, young leaves. Moreover, there seem to be differences in pattern. Relative to (E,E)--farnesene, methyl-salicylate was found in much lower amounts in heavily infested, old leaves. With respect to polyphenols it was found that infested old leaves collected in August have polyphenols with the same retention times, but more or less equal amounts as uninfested young leaves collected in May. This shows thatPsylla infestation causes the induced response mostly in young leaves.The induced leaf volatiles may act as synomones to heteropteran bugs. As shown elsewhere,Anthocoris nemoralis responds significantly to (E,E)--farnesene and methyl-salicylate when offered in pure form against clean air in a Y-tube olfactometer. The effect of polyphenols on the performance ofP. pyricola is not yet known. Hence, a role in direct defence is still to be investigated. 相似文献
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This study examined relationships between mentoring functions offered and transformational leadership as a mentor outcome and affective well‐being and organizational commitment as mutual outcomes for both mentors and protégés. For this examination, we conducted a longitudinal field study by using 111 matched reports from both mentors and protégés collected at three different points in time over seven months in nine Korean companies that administered a standardized formal mentoring program. Study results showed that mentoring functions assessed at Time 2 were positively associated with mentors' and protégés' post‐mentoring outcomes at Time 3 after controlling for pre‐mentoring initial levels of those outcomes at Time 1. Study findings also revealed that relative effects of mentoring on the mentor and protégé outcomes differed by the types of mentoring functions. We discuss the theoretical, practical, and methodological implications from these results. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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为考察羟基磷酸钙(HAP)诱导结晶对低磷污水中PO43--P的回收效果,以污水厂尾水为研究对象,采用方解石为晶种,首先全面对比了HAP诱导结晶与均相结晶的PO43--P去除效果,然后通过改变晶种粒径和投加量,研究了晶种对PO43--P回收的影响,并探讨了结晶反应条件对PO43--P回收和产物晶型的影响.结果表明:HAP诱导结晶除磷效果要优于均相结晶,当结晶体系pH不超过9.0且残余Ca2+为100 mg·L-1时,前者可将PO43--P浓度降至0.5 mg·L-1左右,后者则为5.0 mg·L-1左右.构晶离子的扩散过程是HAP诱导结晶的控速步骤,减小晶种粒径和增加晶种投加量有利于构晶离子的扩散,可提高结晶反应速率,进而提高HAP诱导结晶对低磷污水的适应性,使PO43--P回收率得到提高.对PO43--P浓度为1.0 mg·L-1的模拟废水,晶种投加量为10 g·L-1、粒径为45 μm、Ca2+投加量为50 mg·L-1和pH=9时,在10 min的反应时间内HAP诱导结晶可获得80%以上的PO43--P回收率,出水PO43--P和pH满足GB 3838—2002的Ⅱ类标准(0.1 mg·L-1).实验条件下,HAP诱导结晶产物晶型主要为HAP及其前驱物无定形态羟基磷酸钙(ACP),产物结晶度随着pH的提高和晶种粒径的减小而提高. 相似文献
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The aim of present study was to validate hepatoprotective and antioxidant activities of the bark of Bridelia retusa. The aqueous ethanol extract of B. retusa exhibited highest in vitro hepatoprotective effects as evident from the significantly reduced serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) into the incubation medium of rat hepatocytes with carbon tetrachloride (CCl4), over the other organic extracts (chloroform, ethylacetate, and methanol). CCl4 administered through subcutaneous injection produced a marked elevation in the serum levels of GOT, GPT, lactate dehydrogenase, alkaline phosphatase, bilirubin, thiobarbituric acid reactive substances, and decreased in the levels of reduced glutathione, superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and total protein content. The biochemical activities were normalized in the pretreatment of rats induced by CCl4 with different doses (250 and 500 mg kg?1) of the aqueous ethanol extract of B. retusa. Histopathological changes induced by CCl4 were also significantly attenuated by aqueous ethanol extract of B. retusa treatment. The activity of the aqueous ethanol extract of B. retusa at the dose of 500 mg kg?1 was comparable to the standard drug, silymarin (25 mg kg?1). The overall data indicated that B. retusa possesses a potent protective effect against CCl4-induced hepatic damage and oxidative stress. 相似文献