超期服役的导弹发射装药贮存安全性试验评估

目的研究超期服役的某型导弹发射装药是否满足安全贮存使用要求,结合性能试验准确评估装药的贮存安全性。方法通过分析发射装药性能老化与失效可能引发的安全风险,构建装药贮存安全性评估参数体系。在此基础上,对贮存14 a与5 a的发射装药分别进行结构完整性、力学性能、热安定性、易损性等贮存安全性相关试验。结果通过试验结果与数据分析,获取了对应的评估参数,贮存14 a与5 a的装药性能相比,装药总体结构安全系数由3.85降至2.86。在相同试验温度下,抗拉强度、抗压强度和抗冲击强度的最大降低幅度分别为18.35%、14.05%、7.85%,装药安定剂含量由98%降至93%,摩擦感度与撞击感度分别增高33.28%、36.77%,据此综合评估了发射装药的贮存安全性。结论超期服役的某型导弹发射装药贮存安全性仍满足技术标准要求,装药经过长期贮存后,力学性能和热安定性的劣化程度较小,结构完整性与易损性对应参数变化较大,表明装药的使用安全性明显下降。     

HMX与低熔点含能材料混合物的热安定性研究

目的 研究环四亚甲基四硝胺(HMX)与2,4,6-三硝基甲苯(TNT)、2,4-二硝基苯甲醚(DNAN)、3,4-二硝基呋咱基氧化呋咱(DNTF)3种低熔点、高挥发性含能材料混合后的热安定性及相关性质.方法 将HMX与3种低熔点含能材料按照质量比1:1进行混合,采用动态测压热分析法(DPTA)、差示扫描量热法(DSC)...     

某固体云爆剂老化前后的安全性研究

目的研究某型固体云爆剂老化后的使用安全性。方法采用真空安定性试验仪按GJB772A—97方法 501.2测试老化前后样品的安定性、相容性,采用感度设备按GJB 772A—97中的相应方法分别测试老化前后样品的撞击感度、摩擦感度以及火焰感度。结果云爆剂老化前后,每克试样在标准状态下的放气量均远远小于2 mL,安定性均合格。样品老化前后火焰感度试验均未爆,撞击感度和摩擦感度均在样品在失重1%时最高,当样品老化至失重1.5%时,爆炸概率反而比失重1%样品的降低。结论该型固体云爆剂老化前后均具有良好的安全性,老化失重达到1.5%后,仍能满足安全使用要求。     

某三基发射药老化性能退化规律及失效模式探究

目的 获得某三基发射药老化后性能的退化规律,确定其失效模式,预估贮存及使用寿命.方法 根据某三基发射药实际使用环境及方式,采用温度-湿度双应力加速老化试验,模拟装药条件,获得老化样品.以安定剂含量、抗压强度、燃烧性能和机械感度为监测指标,对老化后样品进行测试,探究其性能变化规律,明确失效模式.通过Berthelot方程...     

新烟碱类农药呋虫胺对映体选择性研究进展

农业生产中,呋虫胺以外消旋体的形式销售和使用,在进入生态环境后出现对映体选择性降解、吸收、代谢、排泄等.不区分对映体间差异的传统风险评估给呋虫胺的合理使用与生态安全带来了诸多隐患.研究指出S-呋虫胺既是高毒体也是高活体,其生态毒性为R-呋虫胺的13.9~145.9倍,但R-呋虫胺也表现出较高的杀虫活性,且作物中优先降解,开发高比例的R体农药有利于维持杀虫活性的同时降低对非靶生物和生态环境的负效应.本文旨在综述呋虫胺对映体选择性生物活性、生态毒性及环境行为研究进展,为其科学难题的解决提供新思路,也为其科学有效管理提供理论依据.     

橡胶及制品自然贮存老化行为研究进展

针对橡胶及制品自然贮存老化行为的研究现状,从宏观性能、微观结构、自然贮存试验方法等方面进行综述。其中,宏观性能主要包括力学性能和其他宏观性能两个方面;微观结构方面主要包括FTIR技术、热分析技术、SEM及XPS技术等三个方面;自然贮存试验方法方面主要是部分橡胶及制品的相关自然贮存试验规范及标准。橡胶及制品自然贮存老化行为研究应加强自然贮存试验,综合运用分析手段掌握橡胶及制品的真实老化行为,从而改善橡胶性能,延长其使用寿命。     

贮存老化对某弹药射程的影响研究

目的 研究长期贮存老化对某弹药射程的影响,确定其有效增程射角范围。方法 对130 mm某弹药在不同贮存老化时间下的射程进行数值仿真分析,揭示其射程和有效增程射角范围随贮存时间的变化规律。结合射程与贮存老化时间和射角之间的函数关系,提出以剩余推力比为表征参数的射程变化模型。结果 在相同贮存老化时间下,随着射角的增大,该弹药的射程呈现出先增大、后减小的趋势。相同射角下,射程随贮存老化时间呈线性下降趋势,有效增程射角范围逐渐减小。使用三次多项式拟合有效增程比与射角之间的函数关系,拟合方程的相关系数超过了0.997 0。该弹药射程变化模型的拟合结果与仿真计算结果的相关系数大于0.998 5,表明其可以准确描述该弹药的射程变化规律。结论 贮存老化会显著影响某弹药的射程和有效增程射角范围,在实际贮存和使用过程中,不能忽略其贮存老化因素。     

基于温度-压力双应力加速试验的NEPE推进剂寿命预估研究

目的 探索实际贮存状态NEPE推进剂自重产生的诱发压力对其贮存寿命的影响,开展温度-压力双应力作用下NEPE推进剂的寿命预估研究.方法 对比分析NEPE推进剂在加速老化试验过程中的失效机理,确定其老化失效模式以及老化失效参量,采用加速老化试验及力学性能测试,分析NEPE推进剂加速老化过程中力学性能的变化规律.基于不同温...     

固体推进剂老化过程影响因素及化学反应机理研究进展

基于固体推进剂的贮存老化,以NEPE推进剂和以HTPB推进剂为代表,综述了近年来固体推进剂老化进程中所受的各种影响因素、作用机制及化学反应机理研究进展。总结了温湿度、应力和环境气氛为代表的外部环境因素,配方性质、组分变化和添加剂等内部影响因素对推进剂老化及贮存失效期限的影响。分别从微观和宏观角度出发,分析了内外部各种影响因素加速或减缓固体推进剂老化进程的作用机制。此外,针对黏合剂、氧化剂、防老剂等化学组分,总结了固体推进剂贮存老化期间发生的氧化交联、分解、降解断链等主要化学反应,并分析了各个反应发生的机理及原因。最后,展望了未来固体推进剂老化影响因素研究的发展趋势,并为今后固体推进剂老化机理及失效模式研究提供了研究思路。     

HTPB药柱老化对SRM内弹道性能的影响及偏差分析

为了定性和定量的描述药柱燃面、密度、燃速等因素对固体火箭发动机（SRM）内弹道性能的影响,在HTPB复合固体推进剂老化研究和SRM内弹道性能预估研究的基础上,分析了HTPB推进剂因贮存老化引起的SRM内弹道性能偏差,建立了性能偏差计算模型。结果表明,老化引起的药柱燃面、密度、燃速变化以及侵蚀燃烧引起的喷喉烧蚀是SRM贮存过程中影响内弹道性能偏差的直接因素,老化引起它们微小的波动都会引起发动机内弹道性能较大的偏离。在发动机寿命预估和进行可靠性分析时必须考虑老化对内弹道性能的影响。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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