The effect of various reaction parameters on bioremediation of perchlorate-contaminated water

The bioremediation was employed to treat perchlorate-contaminated water. All enrichments and growth of mixed cultures were performed in anaerobic acetate medium. Enrichment cultures were started with activated sludge obtained from a local wastewater treatment plant where it predominantly treats domestic wastewater. Several parameters affecting perchlorate removal were examined through batch experiments, these include the amount of domesticated sludge, the acetate concentration, pH, the C/N ratio and the reaction temperature. The results indicated that acetate was an effective carbon source and electron donor. Under the selected conditions, namely 1.0 g domesticated sludge, an acetate concentration of 1.2 g l(-1), pH 8.0, a C/N ratio of 20 at 40 degrees C, 50 mg l(-1) perchlorate could be rapidly reduced to non-detectable levels within 24 h.     

石墨炉原子吸收法直接测定饮用水中的铍、镍、钡

采用石墨炉原子吸收法,使用热解涂层石墨管,加上硝酸镁作基体改进剂,直接测定水中的痕量铍、镍、钡。测定钡时采用原子化阶段不停气,通以10mL/min的流量;测定完成后,再使用“清除温度”空烧1～2次处理,可消除记忆效应的影响。     

一种高精度圆柱形人工边界条件:水-柱体相互作用问题

针对水-柱体动力相互作用问题,提出一种用于模拟无限域水体的圆柱形高精度时域人工边界条件。首先,基于三维可压缩水体的波动方程和边界条件,采用分离变量法建立了时空全局的精确人工边界条件;然后,将其动力刚度表示为外域模型和波导模型人工边界条件动力刚度的嵌套形式;之后,应用时间局部化方法得到时间局部的高精度人工边界条件;最后,离散高精度人工边界条件,并将其与近场有限元方程耦合,形成一种能够采用显式时间积分方法求解的时间二阶常微分方程组。数值算例表明:提出的三维圆柱形高精度人工边界条件精确、高效、稳定。     

故障振动信号的小波包分解与诊断

本文讨论了故障振动在小波分解下的信号特征,给出了小波包分解处理故障振动信号的原理和方法,论述了诊断信号的表达方式及其特点,给出并分析了一个变速箱多故障源的诊断实例.实践证明,作者给出的小波包分解与诊断方法具有理论和实际价值.     

铸铁表面激光熔敷层的抗裂性和耐磨性

采用免预热多道搭接的激光熔敷工艺，在铸铁表面制备出抗裂耐磨的激光熔敷层，研究了激光功率和扫描速度对熔敷层抗裂性的影响。适当的激光功率和扫描速度可以使铁基熔敷层的裂纹率最低．随着Ni含量的增加，熔敷层内奥氏体相体积分数增加；K可促进共晶碳化物团球化，熔敷层抗裂性增强．通过对铸铁表面激光熔敷层裂纹的萌生与扩展的动态观察，揭示了熔敷层开裂的微观机制．裂纹易在粗大渗碳体区或石墨与奥氏体的界面处萌生，奥氏体可明显抑制裂纹的扩展．Ti含量增加使熔敷层中原位自生的TiC的体积分数增大，熔敷层磨损质量损失减少，耐磨性增强．     

Investigation of Nitrite Production Pathway in Integrated Partial Denitrification/Anammox Process via Isotope Labelling Technique and the Relevant Microbial Communities

In this study,the nitrogen removal performance of partial denitrificaiton/anammox(PDA) process was investigated by using an UASB reactor.High total nitrogen(TN) removal efficiency(91.97%) was achieved at an influent nitrogen loading rate of 0.64 kg/(m³·d).Anammox bacteria did execute the function of converting nitrate to nitrite in PDA system according to ¹⁵N isotope labeling experiments and the contribution was approximately 36.3%.Candidatus＿Brocadia,Candidatus＿Kuenenia an...     

固相法合成Ag(Nb0.8Ta0.2)O3的研究

以不同固相合成工艺制备了Ag（Nb0．8Ta0．2）O3粉末，并对其压片烧结后样品的XRD和SEM图进行了分析，对成瓷性较好的样品的介电性能进行了测试．结果表明：不同工艺均可合成具有钙钛矿结构的Ag（Nb0.8Ta0．2）O3（ANT）样品，但对样品成瓷性影响很大．通过先将Nb2O5、Ta2O5在1200℃煅烧，然后再同Ag2O反应生成Ag（Nb0．8Ta0．2）O3的合成工艺，在较低的烧结温度下，就可烧制成粒径均匀、致密的陶瓷，相比其他工艺合成的样品，其介电常数（ε）得到了提高，介电损耗（tanδ）变小，为最佳合成工艺．     

Effect of Seed Layer on the Orientation of Zinc Oxide Film on Silicon Substrate

1. IntroductionZinc oxide films have been attracting more and moreattention because of their high diffractive index, low resis-tance, and photoluminescence properties, and are beingused as transparent electrodes, basis material for opti-cal wave guide devices, gas sensors and so on. Manymethods have been developed to prepare ZnO films, suchas chemical vapor deposition[1], reactive evaporation[2],pulsed laser ablation[3], sputtering[4], spray pyrolysis[5]and hydrothermal method[6]. There are a…     

一种基于信息流脉络网的隐蔽通道搜索方法

针对隐蔽流树搜索方法存在的规模大、分析工作量繁重等问题, 提出一种改进的隐蔽通道搜索方法。该方法采用网结构描述系统中的隐蔽信息流, 提出网中隐蔽通道的判定规则; 依据判定规则在深度优先搜索网中隐蔽通信路径过程中排除合法通道; 结合路径中的操作序列构造隐蔽通道工作场景, 从而发现系统中的隐蔽通道。实例分析和对比表明, 该方法可以弥补隐蔽流树搜索方法的不足。     

Comparison of modified injection molding and conventional machining in biodegradable behavior of perforated cannulated magnesium hip stents

In this study,perforated cannulated magnesium(Mg)hip stents were fabricated via modified Mg injection molding and conventional machining,respectively.Additionally,the stent canal was filled with paraffin to simulate injection of biomaterials.The microstructure,mechanical performance,corrosion behavior,and biocompatibility were comparably studied.Scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)showed higher affinity of interstitial element such as oxygen and carbon as consequences of routine molding process.After immersion in SBF,machining stents showed reduced degradation rate and increased deposition of calcium phosphate compared to molding stents.Corrosion resistance was improved via paraffin-filling.Consistently,the hemolysis and in vitro osteoblast cell culture models showed favourable biocompatibility in machining stents compared to molding ones,which was improved by paraffin-filling treatment as well.These results implied that the feasibility of the prepared machining stents as the potential in vivo orthopaedic application where slower degradation is required,which could be enhanced by designing canal-filling injection of biomaterials as well.