纳米铝粉对烟火药剂热安全性影响研究

为研究铝粉纳米化后对烟火药剂性能的影响,本文将普通铝粉和纳米铝粉分别与氯酸钾、硫粉按照零氧平衡的同一配比（17％AL＋63％KClO3＋20％S）配成的烟火药剂进行ARC热分析对比试验发现,含纳米铝粉的烟火药剂热分解的初始反应温度降低,反应到达最大温升速率所需的时间延长,反应所能达到的最高压力降低。这说明纳米铝粉的加入在加速其反应进程的同时,可有效地降低其反应的激烈程度和危险性,即铝粉纳米化后可以有效的改善烟火药剂的性能,提高其安全性。     

A new approach to quantify the degradation kinetics of linuron with UV, ozonation and UV/O3 processes

The degradation of linuron, one of phenylurea herbicides, was investigated for its reaction kinetics by different treatment processes including ultraviolet irradiation (UV), ozonation (O₃), and UV/O₃. The decay rate of linuron by UV/O₃ process was found to be around 3.5 times and 2.5 times faster than sole-UV and ozone-alone, respectively. Experimental results also indicate overall rate constants increased exponentially with pH above 9.0 while the increase of rate constants with pH below 9 is insignificant in O₃ system. All dominant parameters involved in the three processes were determined in the assistant of proposed linear models in this study. The approach was found useful in predicting the process performances through the quantification of quantum yield (rate constant for the formation of free radical HOO⁻ from ozone decomposition at high pH), rate constant of linuron with ozone (k_O3,LNR), rate constant of linuron with hydroxyl radical (k_OH,LNR), and α (the ratio of the production rate of OH and the decay rate of ozone in UV/O₃ system).     

Cation exchange in a glacial till drumlin at a road salt storage facility

At a former wood preservation plant severely contaminated with coal tar oil, in situ bulk attenuation and biodegradation rate constants for several monoaromatic (BTEX) and polyaromatic hydrocarbons (PAH) were determined using (1) classical first order decay models, (2) Michaelis–Menten degradation kinetics (MM), and (3) stable carbon isotopes, for o-xylene and naphthalene. The first order bulk attenuation rate constant for o-xylene was calculated to be 0.0025 d^− 1 and a novel stable isotope-based first order model, which also accounted for the respective redox conditions, resulted in a slightly smaller biodegradation rate constant of 0.0019 d^− 1. Based on MM-kinetics, the o-xylene concentration decreased with a maximum rate of k_max = 0.1 µg/L/d. The bulk attenuation rate constant of naphthalene retrieved from the classical first order decay model was 0.0038 d^− 1. The stable isotope-based biodegradation rate constant of 0.0027 d^− 1 was smaller in the reduced zone, while residual naphthalene in the oxic part of the plume further downgradient was degraded at a higher rate of 0.0038 d^− 1. With MM-kinetics a maximum degradation rate of k_max = 12 µg/L/d was determined. Although best fits were obtained by MM-kinetics, we consider the carbon stable isotope-based approach more appropriate as it is specific for biodegradation (not overall attenuation) and at the same time accounts for the dominant electron-accepting process. For o-xylene a field based isotope enrichment factor ε_field of − 1.4 could be determined using the Rayleigh model, which closely matched values from laboratory studies of o-xylene degradation under sulfate-reducing conditions.     

Chlorination of chlortoluron: kinetics, pathways and chloroform formation

Chlortoluron chlorination is studied in the pH range of 3-10 at 25 ± 1 °C. The chlorination kinetics can be well described by a second-order kinetics model, first-order in chlorine and first-order in chlortoluron. The apparent rate constants were determined and found to be minimum at pH 6, maximum at pH 3 and medium at alkaline conditions. The rate constant of each predominant elementary reactions (i.e., the acid-catalyzed reaction of chlortoluron with HOCl, the reaction of chlortoluron with HOCl and the reaction of chlortoluron with OCl⁻) was calculated as 3.12 (± 0.10) × 10⁷ M⁻² h⁻¹, 3.11 (±0.39) × 10² M⁻¹ h⁻¹ and 3.06 (±0.47) × 10³ M⁻¹ h⁻¹, respectively. The main chlortoluron chlorination by-products were identified by gas chromatography-mass spectrometry (GC-MS) with purge-and-trap pretreatment, ultra-performance liquid chromatography-electrospray ionization-MS and GC-electron capture detector. Six volatile disinfection by-products were identified including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone, dichloronitromethane and trichloronitromethane. Degradation pathways of chlortoluron chlorination were then proposed. High concentrations of CF were generated during chlortoluron chlorination, with maximum CF yield at circumneutral pH range in solution.     

减灾平衡点

文章依据经济学的原理提出了减灾平衡点的概念,并初步分析了它的特征及其实际意义。所谓减灾平衡点是指社会总体投资利益最大时减灾投资在社会总投资中所占的位置;此时,减灾投资利润率与社会正常生产投资利润率相当。     

A rate of return analysis for public forestry in Ulster

In this paper a rate of return analysis is carried out on public forestry in Northern Ireland. Analysis is based on the results obtained in two very different locations: a 100-hectare acquisition in the western part of the province where the quality of land is generally poor and a 10-hectare plantation in the east where soil and other conditions are reasonably good. The species in question is Sitka spruce, an evergreen variety which is planted for commercial purposes throughout the UK. Rate of return figures obtained here indicate that even with narrow commercial considerations, forestry in Northern Ireland is a sound venture and should expand rapidly to moderate the timber deficiency which exists in the province as well as in the UK and the EEC.     

三维电极法处理苯酚废水影响因素研究

根据电解原理,采用自制三维电极反应器对苯酚废水进行处理。在pH值为3,反应时间为120min,电解电压为15V,极板间距为10cm,曝气强度为0.6m3/h反应条件下,苯酚和COD的最大去除率分别为89.1%和83.2%。表明三维电极法适用于处理浓度较高、且有毒性的废水,是快捷、经济、高效的废水处理方法。     

不同日摄氟量居民罹患氟斑釉的研究

人和动物体内的硬组织（牙齿、骨骼等）是氟化物作用的主要部位,严重者可引起氟骨症和氟斑釉,其中氟斑釉是慢性氟中毒的一项特异指标。通常日摄氟量高的居民其氟斑釉率和斑釉指标均增高。本文用日摄氟量作指标评价环境氟对居民牙齿的影响。研究结果揭示,当地居民的斑釉率和斑釉指数均与日摄氟量呈非常显著的正相关,r＝0.9084,P<0.01。     

表面活性物质对HPMA阻垢缓蚀性能的影响

表面活性物质的加入可明显提高水解聚马来酸酐(HPMA)的阻垢、缓蚀性能,且不同表面活性物质影响程度不同,通过剩余硬度法测定阻垢性能,静态失重法测定缓蚀性能,从而比较异丙醇、葡萄糖酸钠对HPMA阻垢、缓蚀性能的影响。实验结果表明,异丙醇与HPMA复合使用时效果较好,阻垢率达到 79 0 %,缓蚀率达 70 7%,且阻垢率随Ca2 + 浓度增大而增大。     

广州市移动源现状及其污染控制管理对策

通过对广州市机动车辆构成状况和发展趋势、车流变化与氮氧化物变化关系以及各类车型污染排放分担率的分析,结果表明:在排放污染物的移动源中,小型车(出租车及其他小型车)和摩托车是一氧化碳、碳氢化合物的主要排放源;公共汽车等大型车是氮氧化物的主要排放源之一。并提出对广州市机动车污染控制应着重控制摩托车、小型车(特别是轿车,包括出租车)、公共汽车的污染排放。