Inhibitory effect of Cr（Ⅵ） on activities of soil enzymes

To evaluate the influence of various Cr(VI) concentrations (0.05, 0.25, 0.50, 1.00 and 2.00 g/kg) on the activity of soil enzymes, the activities of catalase, polyphenol oxidase, dehydrogenase, alkaline phosphatase in soils were investigated in the incubation experiment with a period of 35 d. The results indicate that all the tested Cr(VI) concentrations significantly inhibit dehydrogenase activity by over 70% after 35 d. The activity of alkaline phosphatase is slightly inhibited during the whole experiment except for on the day 7. Cr(VI) has no obvious effect on the activity of catalase in soil. On the contrary, Cr(VI) stimulates the activity of polyphenol oxidase. The results suggest that dehydrogenase activity can be used as an indicator for assessing the severity of chromium pollution. Foundation item: Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of China; Project(2008SK2007) supported by the Key Program of Science and Technology of Hunan Province, China     

基于溶剂沥青的冷再生沥青混合料性能评价

传统的沥青混合料冷再生技术有乳化沥青和泡沫沥青冷再生,本研究尝试采用所开发的溶剂沥青作为结合料对废旧沥青混合料进行冷再生,提出了试件的成型和养生方法,进行了配合比组成设计并采用热拌沥青混合料的标准对溶剂沥青冷再生混合料的性能进行评价.试验结果表明,溶剂沥青冷再生混合料的水稳定性能、高温稳定性能均满足我国热拌改性沥青混合料规范的性能要求,低温性能虽然不满足改性沥青混合料的要求,但能满足普通沥青混合料规范的性能要求.     

具周期边界的神经传播型方程的初边值问题解的存在唯一性

神经传播型方程的研究是非线性科学和神经科学交叉的前沿课题,既有实际应用背景,又有重要的理论意义.讨论了具周期边界的神经传播和非线性波动混合型方程的初边值问题,利用Galerkin方法及Sobolev空间理论证明了问题整体解的存在唯一性.     

Behavior,distribution and environmental influence of arsenic in a typical lead smelter

A field study was conducted to determine the behavior and distribution of arsenic during the pyrometallurgy process in a typical SKS(Shuikoushan) lead smelter in Hunan province, China. Environmental influences of arsenic in selected samples were evaluated. Arsenic contents in all input and output samples vary from 0.11% in raw lead to 6.66% in collected dust-2. More arsenic is volatilized in blast furnace and fuming furnace(73.02% of arsenic input) than bottom blowing furnace(10.29% of arsenic input).There are 78.97%, 13.69%, 7.31% of total arsenic distributed in intermediate materials, stockpiled materials and unorganized emissions, respectively. Matte slag-2, collected dust-1 and secondary zinc oxide are hazardous based on the arsenic concentrations of toxicity characteristic leaching procedure. According to risk assessment code(RAC) guideline, arsenic in collected dust-1 poses a very serious risk to the surrounding environment, arsenic in speiss, matte slag-2, water-quenched slag and secondary zinc oxide show low risk, while arsenic in matte slag-1, collected dust-2 and post dust has no risk to the environment.     

用电解锰渣制备高铁硫铝酸盐水泥熟料

以湘潭电化集团“两矿法”生产电解二氧化锰排放的电解锰渣（EMR）为原料,采用X射线荧光光谱分析（XRF）、扫描电子显微镜一能谱仪（SEM—EDS）、X射线衍射（XRD）、热重分析（TG）等检测手段对其化学组成、形貌特征、物相结构及物化性质进行了分析．结果表明,电解锰渣是一种富含Si、S、Fe、Ca、Al的材料,可以用作烧制高铁硫铝酸盐水泥（FAC）熟料的原材料．分别考察了煅烧温度、保温时间、电解锰渣掺量对高铁硫铝酸盐水泥抗压强度的影响,当煅烧温度1200℃、保温时间60min、电解锰渣掺量25％左右时为煅烧工艺的最优条件,3d抗压强度最高可达49．8MPa．研究结果可为电解锰渣的资源化利用提供新的途径和方向．     

网络公共资源防护技术研究

提出了一种网络公共资源防护系统,用于有效阻止对网络公共资源的恶意破坏、提高网络资源的末端防护能力、保证信息服务的安全可靠。首先,根据网络公共资源自身的特点和防护需求,为了使整个防护系统能够灵活、高效地运转,设计了一种“监测-处理-恢复-监测”闭环反馈运转机制;然后,介绍了系统中的体系化联动机制和主动防御方法。实验结果表明：平均资源修复速率为本地31.95KB/毫秒,网络16.10KB/毫秒。系统部署后,访问测试网站的平均响应时间仅降低了1.93%,不会影响资源的可用性。     

WO3循环氧化还原法制备超细钨粉的研究

选取三氧化钨为原料,通过5次还原4次氧化制备出超细钨粉,所得金属钨粉的平均粒度约为0.38 μm,比表面积高达3471.79 m2/kg.金属钨粉在低温慢速氧化可得到松散多孔状态的三氧化钨颗粒,还原此种三氧化钨可得到超细钨粉.同时通过实验发现,金属钨粉在规定条件下进行氧化,得到的三氧化钨粒度与初始原料金属钨粉的粒度无关.     

Al、Cu二元合金系烧结过程的原位观察

利用高温光学显微镜（HTOM）对由纯铝粉和纯铜粉制得的二元粉末体系进行了原位烧结试验,原位观察结果表明：经典烧结理论对塑性粉末体系不再适用;该体系烧结的典型物理过程可概括为颗粒边界熔化、晶界熔化、颗粒熔化,最后为合金元素铜的扩散均匀化,而这四个阶段在时间上并不能严格分开,而是交叠进行的;边界熔化受颗粒表面氧化膜破碎、表面曲率和颗粒变形等因素影响;晶界扩散在烧结过程中始终起着非常重要的作用.这些结果为进一步合理制定和优化烧结工艺提供了直接的参照依据.     

Bioleaching of refractory gold ore （ Ⅲ ）——Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

A novel fluidized-bed reactor was designed and installed for bloleaching in a semi-continuous way, by which a process for biuleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied. The arsenic extraction rate reaches 82.5 % after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ferric ion concentration 6.Sg/L and pulp concentration 10%. And leached rate of gold in the following cyanida.tion is over 90%. The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Armmic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92 % and 87.5 % respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.     

基于树形结构的ZigBee能量均衡协议研究

在ZigBee网络的树形拓扑结构中,其网络高层节点面对大量业务时,容易过早耗尽电池能量.针对此问题,提出一种改进的能量均衡路由算法.在改进算法中,综合考虑了网络节点的层次和负载能力.通过计算路由代价,上层节点的功耗被降低,而负载则被分摊至下层节点.另外在路由选择的时候,尽量避开剩余能量较低的节点.仿真结果表明,改进算法可以平衡网络节点的整体耗能,延长关键节点的生存时间,从而提高了ZigBee网络整体的健壮性.