基于实测数据的空空导弹自由飞振动条件制定方法研究

目的基于实测数据来分析和研究空空导弹自由飞振动环境,讨论并建议空空导弹自由飞振动试验条件制定方法。方法针对空空导弹振动数据的特殊性对数据进行处理分析。结果实测数据处理得到空空导弹每个区域的振动响应谱,通过地面试验和动力学仿真分析修订得出地面试验谱。结论要制定一个合理的空空导弹自由飞振动试验条件,必须基于实测数据进行处理分析,并建立在适当的振动实施条件下。     

Optimization of the T3-induced Xenopus metamorphosis assay for detecting thyroid hormone signaling disruption of chemicals

T3-induced Xenopus metamorphosis is an ideal model for detecting thyroid hormone(TH)signaling disruption of chemicals. To optimize the T3-induced Xenopus assay and improve its sensitivity and reproducibility, we intend to develop quantitatively morphological endpoints and choose appropriate concentrations and exposure durations for T3 induction.Xenopus laevis at stage 52 were exposed to series of concentrations of T3(0.31–2.5 nmol/L)for 6 days. By comparing morphological changes induced by T3, we propose head area,mouth width, unilateral brain width/brain length, and hindlimb length/snout-vent length as quantitative parameters for characterizing T3-induced morphological changes, with body weight as a parameter for indicating integrated changes. By analyzing time-response curves, we found that following 4-day exposure, T3-induced grossly morphological changes displayed linear concentration–response curves, with moderate morphological changes resulting from 1.25 nmol/L T3 exposure. When using grossly morphological endpoints to detect TH signaling disruption, we propose 4 days as exposure duration of T3, with concentrations close to 1.25 nmol/L as induction concentrations. However, it is appropriate to examine morphological and molecular changes of the intestine on day 2 due to their early response to T3. The quantitative endpoints and T3 induction concentrations and durations we determined would improve the sensitivity and the reproducibility of the T3-induced Xenopus metamorphosis assay.     

冷却速度对X70管线钢感应加热弯管组织性能的影响

弯管是油气输送管道的重要组成构件之一。冷却速度的快慢决定弯管材料的最终性能 ,是感应加热弯管的关键参数。为确定合适的冷却速度范围 ,研究了冷却速度大小对管线钢材料组织、性能的影响规律 ,确定了保证材料组织性能冷却速度的下限值。     

First trimester screening for Down syndrome and assisted reproduction: no basis for concern

In pregnancies obtained after assisted reproduction the false-positive rate of second trimester Down syndrome (DS) screening is increased by 1.5–3-fold. This may cause an increase in the number of amniocenteses and the fetal loss rate. The present study for the first time examined whether assisted reproductive technologies affect the results of first trimester screening. The markers PAPP-A, free β-hCG and the nuchal translucency (NT) thickness were examined at 12–14 weeks' gestation. Screening markers in 47 in vitro fertilisation (IVF), 63 ovulation induction (OI) and 3026 spontaneously conceived singleton pregnancies were compared. The MoM (multiples of the median) value in the IVF pregnancies was 1.02 (95% CI: 0.85–1.22) for PAPP-A, 1.14 (95% CI: 0.95–1.37) for β-hCG and 0.97 (95% CI: 0.89–1.05) for NT; the MoM value in the OI pregnancies was 0.89 (95% CI: 0.76–1.05) for PAPP-A, 1.08 (95% CI: 0.93–1.25) for β-hCG and 1.02 (95% CI: 0.95–1.11) for NT. The first trimester marker values in assisted reproductive pregnancies and spontaneously conceived pregnancies were not significantly different. Estimated false-positive rates for a risk cut-off of 1:400 varied from 4.7% in IVF pregnancies to 5.1% in OI pregnancies. Therefore the false-positive rate in Down syndrome screening should be independent of the method of conception. Copyright © 2001 John Wiley & Sons, Ltd.     

Xanthobacter flavus DT8降解二噁烷的特性研究

对上海某医药厂污水站好氧池的活性污泥进行长期驯化,分离到1株能以二噁烷为唯一碳源和能源生长的菌株DT8.经生理生化、脂肪酸鉴定和16S rRNA序列分析,确定该菌株为黄黄色杆菌DT8(Xanthobacter flavus DT8).序批实验表明X.flavus DT8可于48 h内完全降解100 mg.L-1二噁烷,并可实现污染物的矿化.随着生物量的增加,该降解过程的细胞得率(以二噁烷计)为0.62 g.g-1,能量消耗系数(δe)为1.00,表明X.flavus DT8代谢二噁烷消耗的能量较少.研究不同温度、pH和营养条件对二噁烷降解的影响,发现二噁烷降解较适宜的温度和初始pH分别为34℃和7.0;在贫营养条件下,即无机盐培养基稀释100倍时,100 mg.L-1二噁烷于48 h的降解率达到65.6%.对X.flavus DT8降解二噁烷可能的诱导机制进行初步研究,结果表明X.flavus DT8对二噁烷的降解不需要经历诱导的过程.本研究揭示了X.flavus DT8直接代谢二噁烷的特性,为生物法净化含二噁烷废水及废气的工程应用奠定了基础.     

低频无极灯降解偶氮染料酸性橙7

以40 W的新型低频感应无极灯(LFEL)作为反应光源,研究了其对于水中难生化降解偶氮染料酸性橙7(AO7)的降解效果.通过专用浸没式反应器研究了这种新型光源降解AO7的有效实验参数,并与传统汞灯光源做了降解AO7的实验对比,用GC-MS检测了主要降解产物小分子,探讨了LEEL对AO7的降解机制及反应活性物质(ROS).结果表明,LFEL对于水中的AO7染料具有较好的降解效果和较高的矿化率,在浸没式反应器中曝气量2 m3·min-1,AO7浓度为20 mg·L-1(7 L)在4 h的反应后能达到94.1%的降解率,而其降解能耗远低于传统汞灯光源.降解贡献来自于两个方面:直接吸收降解和间接通过活性物质(ROS)氧化作用.氧气是ROS的重要来源,加大曝气量会提高降解效率,反应过程中有臭氧的生成.添加淬灭剂显示,·OH对降解反应几乎无贡献,1O2和O2·-则是反应的主要活性物质.     

Integrating agricultural sustainability into policy planning: A geo-referenced framework based on Rough Set theory

We propose a geo-referenced framework for agricultural sustainability assessment aimed at supporting policy planning. The framework is based on Rough Set theory and (i) integrates the three pillars of sustainability; (ii) proposes an easy measurement of agricultural systems’ ability to resist over time (agricultural resilience); (iii) offers easy-to-read results; and (iv) reduces the gap between researchers’ analytical skills and decision-makers’ needs. In the paper, a part of the framework, we present essential and practical notion of Rough Set theory and a case study based on Lombardy Region (Italy). Finally, some values and lacks of the method are discussed.     

Herbicide safeners: Tools for improving the efficacy and selectivity of herbicides

Abstract

Safeners (also known as antidotes) are chemical or biological agents that reduce the toxicity of herbicides to crop plants by a physiological or molecular mechanism. Commercialized safeners are mainly chemical compounds that enhance the tolerance of selected grass crops such as maize (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], rice (Oryza sativa L.), and wheat (Triticum aestivum L.) to chloroacetanilide, thiocarbamate, sulfonylurea, imidazolinone, and aryloxyphenoxypropionate herbicides. In practice, safeners are applied either to the crop prior to planting (seed safeners) or to the soil together with the herbicide, formulated as a prepackaged mixture. Safeners act as "bioregulators”; controlling the amount of a given herbicide that reaches its target site in an active form. A safener‐induced enhancement of the metabolic detoxification of herbicides in protected plants is the most apparent mechanism for the action of all commercialized safeners. Herbicide‐detoxifying enzymes such as glutathione transferases (GST), cytochrome P‐450 monooxygenases (CytP450), esterases, and UDP‐glucosyltransferases are induced by herbicide safeners. At the molecular level, safeners appear to act by activating or amplifying genes coding for these enzymes (e.g., GST).     

Systemically-induced response of cabbage plants against a specialist herbivore, Pieris brassicae

Summary. Plant responses to herbivory might directly affect the herbivore (“direct” defences) or might benefit the plant by promoting the effectiveness of natural antagonists of the herbivores (“indirect” defences). Brussels sprouts attacked by Pieris brassicae larvae release volatiles that attract a natural antagonist of the herbivores, the parasitoid Cotesia glomerata, to the damaged plant. In a previous study, we observed that feeding by caterpillars on the lower leaves of the plant triggers the systemic release of volatiles detectable by the parasitoids from upper leaves of the same plant.?The role of these systemically induced volatiles as indirect defence and the dynamics of their emission were investigated in wind-tunnel dual choice tests with C. glomerata. The systemically induced emission of volatiles varied depending on leaf age and on plant age. Systemic induction affected parasitoid effectiveness, as induced plants could be more easily located by parasitoids than non-induced ones.?The role of the systemic induction as a direct defence was investigated through behavioural and feeding tests with P. brassicae. In dual choice assays, 1st instar larvae preferred to feed and fed more on systemically induced than on non-induced leaves. In single choice assays, the leaf area consumed by caterpillars was larger on systemically induced leaves than on non-induced control leaves. However, caterpillars fed on systemically induced leaves attained the same weight as those feeding on non-induced controls. In addition, P. brassicae pupae whose larvae were fed on systemically induced leaves had longer developmental times than those of larvae fed on non-induced leaves. Adult oviposition behavior was not influenced by systemic induction.?We conclude that systemically induced responses in cabbage might reduce P. brassicae fitness both directly, by affecting their development and feeding behavior and indirectly by making caterpillars and pupae more vulnerable to attack by carnivores. The occurrence of a possible relationship between direct and indirect defence is discussed. Received 24 January 2001; accepted 3 May 2001.     

Organohalogen exposure in a Eurasian Eagle owl (Bubo bubo) population from Southeastern Spain: temporal-spatial trends and risk assessment

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine insecticides (OCs) were analysed in 58 Eurasian Eagle owl (Bubo bubo) unhatched eggs collected between 2004 and 2009 in Southeastern Spain. Levels of p,p′-DDE were found to be higher than in eggs laid by other European owls in the same decade, probably due to the greater agricultural activity in our study area. Compared to other European raptors, exposure to PCBs can be considered intermediate, but low to PBDEs. Land use differences and prey availability were the rationale to divide the study area in two subareas in further assessments. Temporal trends of HCB, p,p′-DDE, β-HCH, PCBs and PBDEs were significantly different in each subarea, generally increasing over time in the Southern but decreasing or remaining stable in the Northern. On the contrary, levels of cyclodienes tended to decrease in both subareas. Dietary shifts with a greater amount of birds are suggested as a cause for increasing organochlorine loads in raptors. This may explain the increasing trend in the Southern territories. However, due to the proximity of most of these nests to Cartagena, an important industrial city, increasing environmental pollution cannot be ruled out. Although average levels of the compounds analysed are below threshold levels, 17% of the samples exceeded 400 pg g⁻¹ ww (wet weight), the LOAEC for Total TEQs. Moreover, a negative correlation between TEQ concentrations and the metabolizable fraction of PCBs (F_prob = 0.0018) was found when TEQs values were above 10 pg g⁻¹ ww. This could be indicative of hepatic enzymes induction in the birds exposed at higher concentrations, which are mainly breeding in the Southern subarea. These females could be suffering from Ah-receptor-related toxic effects, some of which have been related to altered bird reproduction. Finally, a significant negative correlation between p,p′-DDE levels and eggshell thickness (r = −0.469, p < 0.001) was observed, with about 17% of eggshell thinning for eggs with p,p′-DDE levels above 100 μg g ⁻¹ lw. The persistence of this degree of thinning over a period of time has been related to population declines in other raptor species.