The potential use of wetlands to reduce phosphorus export from agricultural catchments

Natural and artificial wetlands have the potential to reduce phosphorus (P) loads from dispersed agricultural runoff and from point sources in the Peel-Harvey catchment, Western Australia. Small experimental systems containing wetland plants and substrate have shown significant removal of P from inflowing water, the proportion of P removed being dependent on P concentration and flow rate of water through the system. The use of artificial wetlands to treat diffuse agricultural runoff is limited by the highly seasonal runoff typical of this Mediterranean climate, while use at point sources has so far been unsuccessful because compounds from the effluent clog the wetland filters. Treatment at point sources may well be feasible after further research.Natural wetlands in the catchment absorb P received in runoff from farmland and, in the absence of any outflow channels to the drainage system, confine this P within the boundaries of the wetland. Disturbance to wetlands may reduce their efficiency in absorbing nutrients and may release P stored in the vegetation and sediment to the water. The conservation of natural wetlands is recommended to maximise nutrient retention in the catchment.     

应用WCA微扰理论推算非极性液体比热容的新方法

本文首次将统计热力学的Ｗｅｅｋｓ－Ｃｈａｎｄｌｅｒ－Ａｎｄｅｒｓｏｎ（简称ＷＣＡ）微扰理论应用于非极性液体定容比热容和定压比热容的推算，用一些液体的ｐ－ｖ－Ｔ实验数据拟合了理论中所用ＬＪ势能函数的势能参数，并提出一个通用关联式。本文方法具有通用性，在编制的计算程序中只需输入物质的临界温度、临界比容、偏心因子等就能算出相应的比热容，工程应用十分方便。     

Electrochemical and surface-enhanced Raman spectroscopy studies of 4-phenylpyridine adsorption at the gold/solution interface

The adsorption of 4-phenylpyridine (4-PhPy) on the Au electrode was examined using conventional electrochemical techniques: cyclic voltammetry and impedance measurements and also by surface enhanced Raman spectroscopy (SERS) in a wide range of electrode potentials. Electrochemical results indicate the strong adsorption of 4-Phpy molecules, particularly at the positively charged Au electrode. The wide shoulder of capacity close to the pzc suggests that the composition and/or the structure of 4-Phpy monolayer change with the sign of the surface charge on the electrode. Investigation of integrity of adsorbed layer, however, indicates that adsorbed molecules do not form tight, compact monolayer even in the case of adsorption from saturated solution. SERS spectra provided evidence for gradual, potential-induced reorientation of the molecular plane with respect to the surface, from nearly vertical in the negatively charged electrode, to more flat at the positively charged metal surface.     

关于中压电缆网双环接线方式供电能力的分析

结合北京地区现阶段对相关技术的规定,以实际供用电方案为例,对中压电缆网双环接线方式的供电能力进行深入讨论。通过设计环网单元划分,发现某些条件下双环网供电能力可以得到进一步提升。     

离网型太阳能光伏发电系统设计研究

离网型太阳能光伏发电系统是太阳能光伏发电系统的重要组成。它具有灵活度高、分布广、项目成本低等优点。本文主要对现有离网光伏发电系统设计过程进行分析。     

Effect of birch (Betula pendula) bark and food protein level on root voles (Microtus oeconomus): II. detoxification capacity

The effect of protein and birch bark powder (BBP) content of forage on detoxification capacity of root voles (Microtus oeconomus) was studied. Young voles were fed with eight different diets for two weeks. Individuals on low (3%) protein diets had significantly lighter livers and kidneys than those on moderate (6%) or high (12%) protein diets. Birch bark powder addition did not have significant effect on organ weight. Detoxification was significantly induced, apparently due to secondary compounds in BBP. The activity of ethoxyresorufin-O-dealkylase (EROD) was high when protein content or BBP concentration in forage was high as compared to low protein diets or diets containing no BBP. Glucuronidation, on the other hand, was not induced by BBP. High BBP content caused serious physiological stress to the voles. The only individuals surviving were those capable of sufficiently allocating energy and protein to detoxification.     

Transitions from solid to liquid in isotactic polystyrene studied by thermal analysis and X-ray scattering

A three-phase model, comprising mobile amorphous fraction (MAF), rigid amorphous fraction (RAF) and crystalline fraction (C), has been applied to interpret the thermal transitions and structure of cold-crystallized isotactic polystyrene (iPS) from below the glass transition temperature, T_g, to above the melting point. Quenched amorphous iPS films were isothermally crystallized at different temperatures for 12 h. The fraction of crystalline phase, ?_c, was measured by differential scanning calorimetry (DSC), wide angle X-ray scattering and Fourier Transform infrared spectroscopy. The fraction of the mobile amorphous phase, ?_MAF, was obtained from the heat capacity increment at the glass transition temperature. In the three-phase model, the fraction of the rigid amorphous phase, ?_RAF, was found from 1−?_MAF−?_c. Specific heat capacity measurements by standard DSC confirm that the experimental baseline heat capacity conforms to a three-phase model for temperatures ranging from below T_g, up to the relaxation of RAF. The relaxation of RAF appears as a sigmoidal change in heat capacity accompanied by excess enthalpy, in which solid-like RAF is converted to an identical amount of liquid-like MAF.At temperatures above the relaxation of RAF, either one or two major crystal melting endotherms are observed in standard DSC, dependent upon crystallization temperature. However, using quasi-isothermal temperature modulated DSC, we always observed two reversing melting endotherms. The effects of annealing on iPS structure during the quasi-isothermal measurement were assessed using small angle X-ray scattering (SAXS). Combining the DSC and SAXS results, a model for the melting of iPS lamellae at low heating rates is presented.     

Dynamic buffering performance of the honeycomb paperboard filled with polyurethane

A new kind of composite buffering material was made by filling the voids of honeycomb paperboard with polyurethane. Drop tests were performed to evaluate the dynamic energy absorption capacity of the material. Based on the tests results, we analyzed the mechanical behaviors of the material under different conditions and obtained the inherent influencing laws of some factors on the material＇s dynamic buffering performance. It was shown that the dynamic buffering performance varied directly with impact velocity, and inversely with the void diameter, thickness and buffeting area of the composite material.     

第二代农民工市民化与中国共产党执政能力建设

第二代农民工市民化利益要求的实现有助于从阶级基础、群众基础、执政理念、执政资源和执政环境等方面加强党的执政能力建设。在第二代农民工市民化背景下,党应该强化执政为民的理念,构建利益相关制度,强化第二代农民工的工人阶级意识和主人翁意识,鼓励他们积极参与政治生活,有组织、有秩序地进行利益表达,使他们充分享受到城市经济社会发展成果,同时提高党自身的执政能力。     

析架空输电线路上倍容导线的选择

架空输电线路项目扩容改造,当采用倍容导线时,需在技术和经济上对倍容导线进行比较分析。文章对这种导线的种类、特性情况作了介绍,通过在220kV线路上对倍容导线的选择分析,为同类案例的处理提供了借鉴和参考。