Metabolic responses of indigenous bacteria in chicken faeces and maggots to multiple antibiotics via heavy water labeled single-cell Raman spectroscopy

The use of maggots derived from chicken faeces as fish diets might serve as a vehicle for the widespread of multiple antibiotic resistant bacteria(ARB) in the environment. Heavy water labeled single-cell Raman spectroscopy(D 2 O-Raman) was applied to detect the metabolic responses of indigenous bacteria in chicken faeces and maggots to different concentrations of combined colistin, kanamycin, and vancomycin. By incubating the samples with D 2 O and antibiotics, metabolically active bacterial cel...     

磁场对紫色非硫光合细菌脱氢酶活性的影响

研究并比较磁场作用下紫色非硫光合细菌（ＰＳＢ）自然细胞和固定化细胞的某些性质。结果表明在最佳磁场作用下２种细胞的热稳定性、ｐＨ稳定性良好。与不加磁场一样,最适温度为３０℃－４０℃,最适ｐＨ值为８,但自然细胞脱氢酶活力比对照组提高１０％－２０％,固定化细胞提高２０％－３０％。磁场使细胞对金属离子（Ｆｅ＾２＋、Ｍｎ＾２＋、Ｍｇ＾２＋）敏感性增加。２种细胞最佳磁场值不同,固定化细胞在最佳磁场作用下在４℃     

固定化细胞生产L-苯丙氨酸研究

用聚乙烯醇（ＰＶＡ）凝胶包埋固定假单胞菌Ｅ４－１０６细胞,最佳ρ（ＰＶＡ）为８０ｇ／Ｌ;最适湿细胞包埋量为每ｍｌ凝胶０．３ｇ;转氨酶活力回收率为７８％,连续反应２１批次后,固定化细胞酶活力为初始最高活力的９１％;用固定化细胞进行间歇式批次反应,结果表明其酶活性半寿期为４个月;制得的固定化细胞为直径约３ｍｍ的珠状颗粒,机械强度良好,间歇式批次反应１０个月,固定化细胞凝胶颗粒无溃破     

自然环境超高加速光老化试验系统研制

目的 设计一种能够高效强化太阳紫外光辐射强度的自然环境加速试验设备,在自然环境环境中,用于高分子材料及制品、零部件的耐光老化高加速试验与快速评估。方法 自然环境超高加速光老化试验系统研制主要采用模块化设计思路,基于3个太阳辐射强化原理,开展紫外反射镜开发,设计系统总体结构、试验主机、太阳能供电分系统和控制分系统等,对主机结构进行有限元强度和变形量分析,开发以PLC为核心的控制系统和以触摸屏及计算机为媒介的人机交互软件。结果 研制的自然环境超高加速光老化试验系统采用太阳能清洁能源供电,实现了40倍以上的太阳紫外辐射强化。结论 研制的自然环境超高加速光老化试验系统加工与制造难度小,加速倍率高,环境友好,使用效费比高,更适用于户外装备用高分子材料及制品的耐光老化评估。     

二氧化锰颗粒对Hela细胞DNA损伤的尺度依赖性毒作用(英文)

为了观察二氧化锰颗粒物所致的尺度依赖性DNA损伤作用,将纳米尺度二氧化锰颗粒物(Nano-MnO2)和常规尺度二氧化锰颗粒物(Nor-MnO2)所致的DNA损伤进行了对比研究.将Hela细胞分别暴露于不同浓度(0、100、200、400μg·mL-1)的Nano-MnO2和Nor-MnO2中,染毒24h,采用彗星实验检测Hela细胞的DNA损伤水平.结果表明:与对照组相比,Nano-MnO2和Nor-MnO2均可使彗尾DNA百分比(TailDNA%)和尾矩(TailMoment)显著增加(p<0.01);而在同一浓度水平上,Nano-MnO2所致的DNA损伤则比Nor-MnO2所致的DNA损伤更为严重(p<0.01).结果提示:二氧化锰颗粒对Hela细胞DNA损伤具有尺度依赖性毒作用,纳米尺度比常规尺度二氧化锰颗粒毒作用更强烈.     

Vero细胞对2,4,6-三氯苯酚的毒性响应特征和敏感性分析

以2,4,6-三氯苯酚(2,4,6-trichlorophenol,TCP)为例,采用MTT比色实验和ANNEXIN V-FITC/PI双染色-流式细胞技术研究了Vero细胞对有机化学污染物的毒性响应特征和敏感性,以期发现一种灵敏、可靠的表征微量化学物质综合毒性的方法.研究结果表明:1)TCP浓度对Vero细胞的毒性响应特征有决定作用.低浓度TCP(≤0.5mg·L-1)即可使部分细胞从原有的刚性不规则三角形结构变为圆形或椭圆形,但细胞的生长未受明显抑制.TCP浓度在1~5mg·L-1时,细胞生长开始受到抑制,表现为细胞增殖受到抑制及部分细胞凋亡或死亡,但增殖抑制率和TCP浓度之间的关系不明显.当TCP浓度大于5mg·L-1时,细胞增殖明显受到抑制,且随TCP浓度的增加,细胞增殖抑制率逐渐升高.2)TCP作用时间对Vero细胞的毒性响应特征有显著影响.ANNEXIN V-FITC/PI双染色-流式细胞仪检测结果表明,TCP作用24h内Vero细胞毒性表现为以细胞膜的完整性受到损伤为主,凋亡或坏死细胞比例较小;而48h后,凋亡细胞的比例明显增加.细胞复壮实验结果进一步证实24h内形态发生变化的细胞并未完全坏死或凋亡.以上结果表明细胞形态变化和细胞膜损伤均为细胞毒性的早期表现特征,两者之间可能存在某种相关性,以此表征化学污染物的生物毒性具有较高的灵敏度,值得进一步研究.     

氧化亚铜光催化降解对硝基苯酚

采用生物效应灯模拟自然光源 ,研究氯化亚铜水解法制备的超细颗粒Cu2 O对对硝基苯酚的光催化降解作用 .结果表明 ,1 1 2mg·l- 1 ,2 2 4mg·l- 1 和 44 8mg·l- 1 对硝基苯酚 1 0h的降解率均达到 90 % ,降解反应符合一级反应动力学 ,且 7次重复使用试验显示 ,催化剂的使用寿命比硼氢化钠法制备的催化剂明显延长 ,降解的主要中间产物为对苯醌与对苯二酚 .     

De facto governance: how authoritative assessments construct climate engineering as an object of governance

ABSTRACT

Analyses of climate engineering (CE) governance have accelerated in the last decade. A key claim is that CE remains a largely ungoverned space, with shared norms, institutional arrangements, and formal rules to regulate CE not yet present. In contrast, here it is argued that de facto governance of CE is underway, discernible in an ordering of this nascent field of inquiry by unacknowledged sources of steering. One key source of de facto governance is analyzed: high-level ‘authoritative assessments’ of CE. The focus is on how these assessments are constructing CE as an object of governance through demarcating and categorizing this emerging field of inquiry, and how this contributes to normalizing and institutionalizing CE research (and CE research communities). Scrutinizing the distinct nature and political implications of de facto governance, particularly of novel and speculative technological trajectories not yet subject to formal steering, remains a key task for governance scholars.     

Comparison of the Photodegradation of Imazethapyr in Aqueous Solution,on Epicuticular Waxes,and on Intact Corn (Zea Mays) and Soybean (Glycine Max) Leaves

A direct, controlled comparison of the photodegradation of imazethapyr has been made between imazethapyr in aqueous solutions, imazethapyr on the surface of epicuticular waxes of corn and soybean plants, and imazethapyr on the surface of intact corn and soybean plant leaves. In some experiments, the imazethapyr solutions were allowed to evaporate partially or fully after application to better model environmental conditions. The photodegradation of imazethapyr was fastest in aqueous solutions (k?=?0.16?±?0.02?h^?1) and slowest on the surface of corn and soybean plants (k_corn?=?0.00048?±?0.001?h^?1 and k_soy?=?0.00054?±?0.003?h^?1). Experiments allowing evaporation during irradiation have intermediate rate constants (e.g., k_corn?=?0.082?±?0.005?h^?1). Finally, identification of photoproducts was also examined on epicuticular waxes of corn and soybean plants for the first time.     

Toxicological response of silver catfish (Rhamdia quelen) after acute exposure to a commercial insecticide containing thiamethoxam

Abstract

This study assessed the hematological, enzymatic and osmoregulatory responses of silver catfish (Rhamdia quelen) exposed to sublethal concentrations (1.125 and 3.750?µg/L) of a commercial thiamethoxam-containing insecticide used on rice crops. Groups of 6 fish per tank (in triplicate, n?=?3, total 54 fish) were exposed for up to 96?h to different concentrations of the compound. After this period, fish were placed in clean water for 48?h. Two fish from each tank (6 per treatment) that had been exposed to the insecticide for 24?h were anesthetized with eugenol and blood was collected to evaluate hematological and biochemical parameters. Blood, liver and muscle were collected for determination of metabolic parameters, plasma cortisol, Cl^-, Na⁺ and K⁺ levels and H⁺-ATPase and Na⁺/K⁺-ATPase activity in the gill. H⁺-ATPase activity was higher in fish exposed to 1.125?µg/L insecticide at 24?h compared to control (0.0?µg/L). Differences in cortisol levels were evidenced throughout the experimental period. These results indicated that exposure to the insecticide changed the hematological, biochemical and metabolic profile of the animals, suggesting concern about environmental safety. Therefore, we discourage the use of this pesticide in areas that come into contact with water bodies inhabited by fish.