Acid resistance of methanogenic bacteria in a two-stage anaerobic process treating high concentration methanol Wastewater

In this study, the two-stage upflow anaerobic sludge blanket (UASB) system and batch experiments were employed to evaluate the performance of anaerobic digestion for the treatment of high concentration methanol wastewater. The acid resistance of granular sludge and methanogenic bacteria and their metabolizing activity were investigated. The results show that the pH of the first UASB changed from 4.9 to 5.8 and 5.5 to 6.2 for the second reactor. Apparently, these were not the advisable pH levels that common methanogenic bacteria could accept. The methanogenic bacteria of the system, viz. Methanosarcina barkeri, had some acid resistance and could still degrade methanol at pH 5.0. If the methanogenic bacteria were trained further, their acid resistance would be improved somewhat. Granular sludge of the system could protect the methanogenic bacteria within its body against the impact of the acidic environment and make them degrade methanol at pH 4.5. The performance of granular sludge was attributed to its structure, bacteria species, and the distribution of bacterium inside the granule. Translated from Acta Scientiae Circumstantiae, 2004, 24(4): 633–636 [译自: 环境科学学报]     

污染生态学的新发展—污染进化生态学

污染胁迫的最显著效应是消除敏感物种或个体，导致植物居群进化。突变是进化的原料，选择是进化的手段，隔离是进化的条件，控制抗性性状的基因因物种及污染物的种类不同而异，但也会出现植物同时具有对某两种或几种污染物的抗性，即所谓协同抗性；污染除使植物衰退外，还可能导致一些遗传信息丧失，使抗性种群内物种单一，降低其适合度，对其它环境胁迫因素的抵抗力下降，即所谓适应代价。     

热镀锌板表面钝化时的磷化工艺

热镀锌板表面钝化（铬酸盐钝化），主要是为了防止在使用过程中其表面被氧化。由于表面的钝化膜的存在。使得磷化工艺无法进行，从而影响涂装后涂层的附着力（铬酸盐钝化膜不如磷化膜附着性好）和耐蚀性能（铬离子不耐氯离子的腐蚀）。为了提高热镀锌板表面钝化后其表面的涂装性能，开发出一种适合上述条件的磷化工艺。     

真丝绸阻燃整理

综述了真丝绸燃烧性能及其阻燃整理的发展历史，总结了真丝绸的各种阻燃方法及具体工艺并对各种方法阻燃性能的优劣作了评价，归纳了真丝绸阻燃所用阻燃剂的种类及各类阻燃剂的作用机理，并指出目前真丝绸阻燃主要存在的问题以及今后的发展方向。     

Starch- polyvinyl alcohol crosslinked film— performance and biodegradation

Starch-PVOH cast films were prepared with and without crosslinking agent (hexamethoxymethylmelamine) in the absence of plasticizer. Moisture absorption in films without crosslinking agent at a low relative humidity was similar to that of PVOH and increased as the relative humidity increased. Films with crosslinking agent showed moisture absorption linearly proportional to the relative humidity. Significant improvement in resistance to water disintegration for crosslinked starch-PVOH films was observed. While the tensile strength decreased with increased relative humidity, crosslinking significantly improved the tensile strength. Increased PVOH content improved elongation of films even when the relative humidity was 80% or higher. Biodegradation studies revealed that the degradation rate was negatively correlated with the PVOH content in films and crosslinking generated more converged degradation curves. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

防辐射有机玻璃板材的抗辐射性能

系统研究了含铅有机玻璃、含钡有机玻璃、含硼有机玻璃和普通有机玻璃的ｘ、γ射线和中子射线防护性能及其耐６０Ｃγ射线辐照稳定性。结果表明，含铅有机玻璃板材具有良好的ｘ射线、反应堆热柱γ射线屏蔽性能；合硼有机玻璃板材具有良好的热中子屏蔽性能；含钡有机玻璃板材的褪化裂变谱中子辐射屏蔽性能良好；含钡有机玻璃和普通有机玻璃可耐１０５～１０６Ｇｙ的６０Ｃｏｙ射线辐照；含铅有机玻璃板材耐６０Ｃｏｙ射线照射能力小于１０５Ｇｙ。     

后张梁管道摩阻损失测试技术与数据处理

针对常规测试中存在的问题 ,改进了管道摩阻损失的测试方法 ,消除了喇叭口等因素影响 ,使得管道摩阻测试更加合理和准确。介绍了后张法预应力管道摩阻损失的计算 ,结合秦沈客运专线双线整孔简支箱梁的管道摩阻损失测试 ,利用最小二乘原理对测试数据进行处理 ,得到了摩阻系数 μ和k的计算公式 ,所得参数为施工提供了依据。最后讨论了摩阻系数对张拉控制应力的影响 ,提出现场测试的一般性原则和要求。     

A Parallel Study of SAR Levels in Head Tissues for Three Antennas Used in Cellular Telephones: Monopole, Helix and Patch

Summary This paper is a comparative study of several antennas commonly used in cellular telephones. These include a monopole, a helix-monopole and a patch antenna. Each one of these structures is modeled and numerically tested using finite-difference time-domain simulation and human models based on magnetic-resonance images, which allow for inclusion of details of the human body in the simulation. The testing procedure involves antenna simulation in the proximity of the human head. The behavior of each antenna is evaluated for variable distances from the head geometry (0, 1, 2, 4, 8 and 16 mm). Continuous waveform, representative of the sources used in mobile telephones, (250 mW, 1.8 GHz) is used as the form of the antenna excitation. The simulation outputs used as measures for this comparative study include transmitting and receiving antenna characteristics and the specific absorption rate (SAR). The SAR levels for the head tissues are calculated for and with accordance to the two currently accepted standards: Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP). The computed SAR levels within each of the considered tissues vary for the three antennas under investigation and are within the determined health safety standards. Results suggest that the patch antenna may be the structure of choice when considering safety standards, as its radiation yields the lowest local SAR in the head tissues.     

Trait space of rare plants in a fire‐dependent ecosystem

The causes of species rarity are of critical concern because of the high extinction risk associated with rarity. Studies examining individual rare species have limited generality, whereas trait‐based approaches offer a means to identify functional causes of rarity that can be applied to communities with disparate species pools. Differences in functional traits between rare and common species may be indicative of the functional causes of species rarity and may therefore be useful in crafting species conservation strategies. However, there is a conspicuous lack of studies comparing the functional traits of rare species and co‐occurring common species. We measured 18 important functional traits for 19 rare and 134 common understory plant species from North Carolina's Sandhills region and compared their trait distributions to determine whether there are significant functional differences that may explain species rarity. Flowering, fire, and tissue‐chemistry traits differed significantly between rare and common, co‐occurring species. Differences in specific traits suggest that fire suppression has driven rarity in this system and that changes to the timing and severity of prescribed fire may improve conservation success. Our method provides a useful tool to prioritize conservation efforts in other systems based on the likelihood that rare species are functionally capable of persisting.     

平原河网地区非点源污染风险差异化分区防控研究

土地利用优化和空间防控策略对非点源污染风险控制及水环境质量的改善具有重要意义。本文以太湖流域典型平原河网地区-上海市青浦区为研究对象,将灰色线性规划模型与最小累积阻力模型相结合,以控制非点源污染风险和增加经济效益、生态效益为目标,进行土地利用结构优化与空间分区防控研究,在空间上划设了水资源保育区、水资源重点防护区、非点源污染一般阻控区、非点源污染中等阻控区及非点源污染重点阻控区,并针对不同分区提出具有针对性的防控措施。与2012年相比,预测2020年优化防控方案下,可减少总氮、总磷的输出10.96%和41.33%。由此表明,优化土地利用结构和构建空间差异化防控机制是有效调控非点源污染风险,实现区域可持续土地利用,促进经济发展和保证生态环境安全的有效途径。