Novel approach to predicting hormetic effects of antibiotic mixtures on Vibrio fischeri

The determination of the hormetic effects of a mixture is quite difficult because of the moderate simulation and the complexity of measurement in low doses. In the present study, two typical models for mixture toxicity prediction, concentration additive (CA) and independent action (IA), were used to predict the hormetic effects of mixtures. The predictive power of those models was validated by the hormetic effects (24-h exposure) of antibiotic’s binary mixtures to Vibrio fischeri. The results showed that CA and IA were unable to predict the hormetic dose-response of mixture, especially those of the interactive mixtures. As an alternative, a novel model, which was named as “six-point” and developed based on the quantitative features in the determined dose-response curve and on the Quantitative Structure Activity Relationships (QSARs) approach, was proposed for predicting the hormetic effects of mixtures in low dose. The results indicated that the “six-point” model can accurately predict the mixture hormetic effects in low dose, not only for non-interactive mixtures but also for interactive mixtures. Therefore, the “six-point” model is a powerful tool to predict the mixture hormetic effects at low dose, and may offer an important approach in the environment risk assessment of mixtures.     

Emissions and distribution of methyl bromide in field beds applied at two rates and covered with two types of plastic mulches

A field experiment was conducted to compare two plastic mulches and two application rates on surface emissions and subsurface distribution of methyl bromide (MBr) in field beds in Florida. Within 30 minutes after injection of MBr to 30 cm depth, MBr had diffused upward to soil surface in all beds covered with polyethylene film (PE) or virtually impermeable film (VIF) and applied at a high rate (392 kg/ha) and a low rate (196 kg/ha). Due to the highly permeable nature of PE, within 30 minutes after injection, MBr volatilized from the bed surfaces of the two PE-covered beds into the atmosphere. The amount of volatilization was greater for the high rate-treatment bed. On the other hand, volatilization of MBr from the bed surfaces of the two VIF-covered beds were negligible. Volatilization losses occurred from the edges of all the beds covered with PE or VIF and were greater from the high rate-treatment beds. Initial vertical diffusion of MBr in the subsurface of the beds covered with PE or VIF was mainly upward, as large concentrations of MBr were detected from near bed surfaces to 20 cm depth in these beds 30 minutes after injection and little or no MBr was found at 40 cm depth. The two VIF-covered beds exhibited greater MBr concentrations and longer resident times in the root zone (0.5–40 cm depth) than corresponding PE-covered beds. Concentrations of MBr in the root zone of the high rate-treatment beds were 3.6–6.1 times larger than the low rate-treatment beds during the first days after application. In conclusion, VIF promoted retention of MBr in the root zone and, if volatilization loss from bed edges can be blocked, volatilization loss from VIF-covered beds should be negligible.     

不同氧浓度下脱脂餐厨垃圾燃烧特性及动力学研究

利用热重分析法和Coats-Redfern积分法,对不同氧浓度下脱脂餐厨垃圾的燃烧特性进行研究,得到了各试样的着火温度、燃烬温度及综合燃烧特性指数,并通过燃烧动力学分析得到各试样的活化能。实验结果表明,燃烧温度从室温升至1 000℃时,脱脂餐厨垃圾燃烧过程可分为3个失重阶段:水分析出阶段、挥发分析出及燃烧阶段和固定碳燃烧阶段;随着氧浓度的升高,脱脂餐厨垃圾最大失重率以及燃烧特性指数等燃烧特性参数都有显著变化。根据Coats-Redfern积分法计算得低温和高温阶段的活化能分别为83.76~91.2 k J/mol和95.25~141.7 k J/mol。     

GIS在水稻“寒露风”冷害监测预警中的应用

水稻低温冷害是广西的主要农业气象灾害,低温冷害的实时监测预警对农业趋利避害和减轻灾害损失十分重要。依托GIS技术和统计学方法,利用1∶25万的经度、纬度、海拔高度等广西基础地理信息数据,按照1 km×1 km的较高空间分辨率,对低温冷害的相关气象数据进行细网格空间分析推算,结合广西水稻生长发育状况和"寒露风"低温冷害受害指标,实现对广西水稻冷害发生发展及其强度、范围的实时监测预警,并以2010年10月上中旬冷害过程为例检验了监测效果,与冷害实际情况比较相符。     

Improved soil fumigation by Telone C35 using carbonation

Soil fumigation to control pests and pathogens is an important part of current agricultural practice. A reduction in fumigant emissions is required to ensure worker safety and environment health. A field trial in Florida was conducted to investigate whether carbonating Telone C35? ((Z)- and (E)-1,3-dichloropropene with 35 % chloropicrin) would improve the delivery of the fumigant to such an extent that the application rate could be decreased without sacrificing efficacy. All treatments were carried out in three replications in a complete block design. The use of carbon dioxide (CO(2)) to carbonate and pressurize Telone C35 provided quicker and deeper distribution initially compared to application by nitrogen gas (N(2)) pressurization. The deeper distribution of Telone C35 components found with CO(2) application may have lowered the initial concentration of Telone C35, but it did not appreciably alter the disappearance rate of the three chemicals, chloropicrin, (Z)- and (E)-1,3-dichloropropene. The faster vertical distribution within the bedded soil of the Telone C35 by CO(2) did enhance volatilization of the active ingredients into the atmosphere compared to volatilization of similar reduced rate applied by N(2) pressurization. However, the cumulative amount volatilized from the carbonated fumigant beds at 75 % application rate was lower than the cumulative amount emitted by full rate of Telone C35 using N(2). The efficacy of the carbonated Telone C35 at a lower application rate was statistically equivalent to that of non-carbonated fumigant using N(2) pressurized injection at a higher application rate, based on weed enumeration and the root-knot nematode galling index.     

光-Fenton氧化破解剩余污泥和改善污泥脱水性能

利用紫外光-Fenton（光-Fenton）氧化处理城市剩余污泥,通过上清液的SCOD、多聚糖以及蛋白质浓度表征污泥胞外聚合物（EPS）的破解情况,通过污泥过滤比阻（SRF）和滤饼含水率表征污泥脱水性能的变化。结果表明,光．Fenton氧化破解污泥EPS和改善污泥脱水性能的效能明显优于单独Fenton反应和单独紫外光照射处理。pH为3、反应时间为2h,H2O2投加量为4g／L和Fe^2＋投加量为0．6mg／L是光-Fenton氧化处理供试污泥的适宜条件。在适宜处理条件下,污泥上清液中的SCOD、多聚糖和蛋白质浓度分别由67．46mg／L、12．53mg／L和8．62mg／L增加到568．12mg／L、448．62mg／L和292．94mg／L;SRF和滤饼含水率分别由2．4×10^S2／g和88．52％下降至5．26×10^8S^2／g和76．36％。光-Fenton反应在有效破懈污泥的同时,提高了污泥的脱水性能．有利于污泥的减量化。     

钢筋混凝土结构构件局部地震损伤多尺度监测方法

提出一种结构局部地震损伤过程的多尺度监测方法。首先,在混凝土材料尺度上,针对混凝土材料细观随机性影响问题,基于压电智能骨料进行混凝土压应力监测,通过试验方法建立了混凝土损伤全过程中压电智能骨料应力与混凝土宏观应力的概率统计关系;其次,在截面尺度上,基于MEMS倾角仪转动监测方法,提出混凝土压弯构件截面曲率的监测方法,并通过试验验证了该方法的可行性;最后,在构件尺度上,提出基于转动积分的层间变形监测方法并给出了转动监测位置的设计原理,通过构件试验验证了该监测方法的可靠性。     

硫酸盐还原作用对废水厌氧处理的影响

采用半连续流运行方式研究了硫酸盐还原作用对废水厌氧处理的影响。试验结果表明:当温度为35℃,pH为7.2～7.4时,进水COD/SO42-≥10,硫酸盐还原作用不致于对产甲烷菌产生严重抑制;进水COD/SO42-≥5,反应器能承受的COD负荷小于2.05kg/ (m3·d),超过这一负荷,反应器会发生严重抑制;进水COD/SO42-≥2,反应器能承受的COD负荷小于1.0kg/(m3·d)。进水COD/SO42-比值越小,反应器能承受的COD负荷越低。反应器污泥浓度高有利于硫酸盐废水的处理。      

连云港海州湾海域赤潮生物的种类调查及形成原因

以光学显微镜对在2003-2006 年连云港海州湾附近海域采集的浮游生物进行观察,初步鉴定出赤潮的种类,并对形成赤潮的原因进行了分析,期望该调查分析结果对于海州湾附近海域生态研究,摸清赤潮的成因和过程,定期监测,减少灾害的发生有一定的促进作用.     

大气中CO2与O3浓度升高对植物光合作用影响研究

随着工业化进程的加快,两种温室气体CO2和O3在大气中浓度不断升高,对植物光合作用产生重要影响.通过从气体交换参数、光合色素含量、叶绿素荧光特性、光合酶、生物量及产量等多方面分析国内外CO2O3单独作用及复合作用对植物光合过程和机理、光合作用物质基础及光合产物的影响,深入了解两种污染气体作用下植物光合响应机制,以期为植物光合作用分子水平的研究以及有效应对未来全球大气变化提供理论依据.