Empirical corroboration of an earlier theoretical resolution to the UV paradox of insect polarized skylight orientation

It is surprising that many insect species use only the ultraviolet (UV) component of the polarized skylight for orientation and navigation purposes, while both the intensity and the degree of polarization of light from the clear sky are lower in the UV than at longer (blue, green, red) wavelengths. Why have these insects chosen the UV part of the polarized skylight? This strange phenomenon is called the "UV-sky-pol paradox". Although earlier several speculations tried to resolve this paradox, they did this without any quantitative data. A theoretical and computational model has convincingly explained why it is advantageous for certain animals to detect celestial polarization in the UV. We performed a sky-polarimetric approach and built a polarized skylight sensor that models the processing of polarization signals by insect photoreceptors. Using this model sensor, we carried out measurements under clear and cloudy sky conditions. Our results showed that light from the cloudy sky has maximal degree of polarization in the UV. Furthermore, under both clear and cloudy skies the angle of polarization of skylight can be detected with a higher accuracy. By this, we corroborated empirically the soundness of the earlier computational resolution of the UV-sky-pol paradox.     

Dry deposition of PM10 over the Yellow Sea during Asian dust events from 2001 to 2007

Dry deposition velocities and fluxes of PM10during Asian dust events over the Yellow Sea from 2001 to 2007 were investigated using observation data in Qingdao, China and Jeju, Korea. The dry deposition velocities of PM10 during dust events over the Yellow Sea ranged from 0.19 to 8.17 cm/sec, with an average of 3.38 cm/sec. Dry deposition fluxes of PM10during dust events over the Yellow Sea were in the range of 68.5–2647.1 mg/(m2·day), with an average of 545.4 mg/(m2·day), which is 2–10 times higher than those reported by other studies for both dust and non-dust periods. It was estimated that 2.6 × 1011–48.7 × 1011g dust particles deposit to the Yellow Sea during dust events through dry deposition every year. Compared with the results in previous studies, it was found that the dry deposition of PM10over the Yellow Sea during dust events in the years with high frequency of dust could account for a large or overwhelming fraction of the annual total dry deposition. Backward air mass trajectory analysis showed that dust events influenced Jeju mainly originated from the desert regions located in Mongolia and Inner Mongolia, China. There were 119 backward trajectories influenced both Qingdao and Jeju during 15 dust events from 2001 to 2007, accounting for 61.3% of the total trajectories of 194, indicating that Qingdao and Jeju were usually on the same pathway of dust transport downwind from source areas.     

Characterization of a salt-tolerant bacterium Bacillus sp. from a membrane bioreactor for saline wastewater treatment

High salt concentrations can cause plasmolysis and loss of activity of cells, but the salt-torlerant bacterium can endure the high salt concentrations in wastewater. In this research 7 salt-torlerant bacteria, which could survive in dry powder products and could degrade organic contaminants in saline wastewater, were isolated from a membrane bioreactor. The strain NY6 which showed the fastest growth rate, best property for organic matter degradation and could survive in dry powder more than 3 months was selected and characterized. It was classified as Bacillus aerius based on the analysis of the morphological and physiological properties as well as the 16 S rRNA sequence and Neigh borjoining tree. The strain NY6 could survive in the salinity up to 6% and the optimal growth salinity is2%; it belongs to a slightly halophilic bacterium. The capability of its dry powder products for COD removal was 800 mg COD/(g·day) in synthesized saline wastewater with salinity of 2%. According to salt-tolerant mechanism research, when the salinity was below 2%, the stain NY6 absorbed K+and Na+to maintain osmotic equilibrium, and when the salinity was above 2%, the NY6 kept its life by producing a large amount of spores.     

Color removal from dye-containing wastewater by magnesium chloride

Color removal by MgCl(2) when treating synthetic waste containing pure dyes was studied. The color removal efficiency of MgCl(2)/Ca(OH)(2) was compared with that of Al(2)(SO(4))(3), polyaluminum chloride (PAC) and FeSO(4)/Ca(OH)(2). The mechanism of color removal by MgCl(2) was also investigated. The experimental results show that the color removal efficiency of MgCl(2) is related to the type of dye and depends on the pH of the waste and the dosage of the coagulants used. Treatment of waste containing reactive dye or dispersed dye with MgCl(2) yielded an optimum color removal ratio when the pH of the solution was equal to or above 12.0. For both the reactive and dispersed dye waste, MgCl(2)/Ca(OH)(2) was shown to be superior to MgCl(2)/NaOH, Al(2)(SO(4))(3), PAC and FeSO(4)/Ca(OH)(2) for color removal. A magnesium hydroxide precipitate formed at pH values greater than 12.0, which provided a large adsorptive surface area and a positive electrostatic surface charge, enabling it to remove the dyes through charge neutralization and an adsorptive coagulating mechanism. So, the MgCl(2)/Ca(OH)(2) system is a viable alternative to some of the more conventional forms of chemical treatment, especially for treating actual textile waste with high natural pH.     

Surface seals reduce 1,3-dichloropropene and chloropicrin emissions in field tests

Reducing emissions is essential for minimizing the impact of soil fumigation on the environment. Water application to the soil surface (or water seal) has been demonstrated to reduce 1,3-dichloropropene (1,3-D) emissions in soil column tests. This study determined the effectiveness of water application to reduce emissions of 1,3-D and chloropicrin (CP) in comparison to other surface seals under field conditions. In a small-plot field trial on a Hanford sandy loam soil (coarse-loamy, mixed, superactive, nonacid, thermic Typic Xerorthents) in the San Joaquin Valley, CA. Telone C35 (61% 1,3-D and 35% CP) was shank-applied at a depth of 46 cm at a rate of 610 kg ha-1. Soil surface seal treatments included control (no tarp and no water application), standard high density polyethylene (HDPE) tarp over dry and pre-irrigated soil, virtually impermeable film (VIF) tarp, initial water application by sprinklers immediately following fumigation, and intermittent water applications after fumigation. The atmospheric emissions and gas-phase distribution of fumigants in soil profile were monitored for 9 d. Among the surface seals, VIF and HDPE tarp over dry soil resulted in the lowest and the highest total emission losses, respectively. Intermittent water applications reduced 1,3-D and CP emissions significantly more than HDPE tarp alone. The initial water application also reduced emission peak and delayed emission time. Pre-irrigated soil plus HDPE tarp reduced fumigant emissions similarly as the intermittent water applications and also yielded the highest surface soil temperature, which may improve overall soil pest control.     

整治火灾隐患与完善火灾隐患整改机制

本文从分析和归纳火灾隐患产生的主要原因入手,阐明规范和完善火灾隐患整改机制势在必行,并从完善责任体系、运用市场调节手段、发挥行政监管职能和解决整改资金等方面论述如何完善火灾隐患整改机制.     

FDS在中庭烟气控制系统设计中的应用

介绍了中庭烟气控制系统的设计方法,分析了FDS(Fire Dynamics Simulator)应用于烟气控制系统设计的理论基础,给出了FDS在中庭烟气控制系统设计中的应用方法.最后通过具体的应用实例,以及和其它设计方法相比较,表明将FDS应用于中庭烟气控制系统的设计中,可提高设计方案的可靠性、经济性.     

从分子质量的变化分析有机物对GAC吸附内分泌干扰物(BPA)的影响

从分子质量分布的角度研究了水中有机物对颗粒活性炭(GAC)吸附双酚A(BPA)容量及吸附速率的影响.结果表明,相对于以去离子水为本底的BPA溶液来说,GAC吸附以滤后水、臭氧后出水和原水为本底的BPA溶液的Langmuir模型的最大吸附容量q_m值分别下降了29.95%、43.56%和44.44%,而其拟二级动力学模型的k₂值分别下降了43.05%、49.75%和56.38%.相对分子质量3 000以上,尤其是10 000以上的有机物堵塞GAC的二级微孔;3 000以下,尤其是1 000以下的有机物与BPA分子之间存在直接的竞争吸附,是导致GAC对BPA的吸附容量以及吸附速率下降的主要原因.     

测氧仪使用及维护中应注意的几个问题

测氧仪广泛用于石化行业的受限空间缺氧或富氧检测.在简要介绍测氧仪核心--伽伐尼氧气传感器工作原理的基础上,分析了影响毛细管式氧气传感器工作的主要因素,结合工作实践,提出了使用维护测氧仪的几条建议.     

安全评价对加油站的作用

1安全评价的含义 安全评价,就是以实现系统安全为目的,运用安全系统工程的原理和方法,对系统中存在的危险、有害因素进行辨识与分析,判断系统发生事故和职业危害的可能性及其严重程度,从而为制定防范措施和管理决策提供科学依据.