煤炭絮凝微生物黄孢原毛平革菌光谱及电镜研究

选择对煤炭具有良好絮凝效果的黄孢原毛平革菌作为研究对象,在对其生物学特性的研究基础上,采用紫外光谱、红外光谱及扫描电镜对其成份进行测试分析。研究结果表明,黄孢原毛平革菌生物提取物中含有大量酸性多糖等具有絮凝作用的组分,不含蛋白质和核酸成分,絮凝生物大分子具有多孔的线型分子结构,包埋交织,结构较致密,并有较多的吸附位点等。     

煤矸石制备白炭黑的试验及机理研究

以淮南煤矸石为原料,经煅烧活化、脱杂、烧碱熔硅和乙醇的作用,最后酸中和等工艺过程,制得非晶态、粒度可达纳米级的白炭黑。主要考察了煤矸石煅烧活化温度、碱用量、乙醇浓度等对白炭黑产率和性质的影响,并利用激光粒度分布测试仪、X射线衍射仪、扫描电子显微镜等对产品进行了表征。对制备过程的机理进行了分析和探讨。     

微生物絮凝煤泥水试验及其红外光谱研究

采用正交试验方法考察了黄孢原毛平革菌对煤泥水的絮凝作用。研究结果表明,黄孢原毛平革菌对煤泥水有很好的絮凝效果,絮凝试验最优工艺组合为:培养时间为2 d,助凝剂量为2 mL,菌液量为2 mL,絮凝剂种类为破碎液,pH值为6。红外光谱测试分析表明,黄孢原毛平革菌生物提取物中含有大量酸性多糖等具有絮凝作用的组分,其生物絮凝剂分子和煤泥水颗粒之间能够通过"吸附架桥"起到絮凝作用。     

Effects of nitrogen doping on surface-enhanced Raman scattering (SERS) performance of bicrystalline TiO2 nanofibres

In this work, we successfully synthesized bicrystalline anatase/TiO_2(B) nanofibre and used it as active substrate for surface-enhanced Raman scattering(SERS) applications. The bicrystalline structured TiO_2 substrates provide additional charge transfer across the anatase-TiO_2(B) interface and thus enhanced activity compared to the pure single crystalline phase. With an effort to further increase the sensitivity of SERS, nitrogen element was doped into bicrystalline anatase/TiO_2(B) nanofibres(N-TiO_2) and higher SERS enhancement was achieved. The nitrogen content was controlled by tuning the calcination temperature of titanate precursor at 500, 600 and 700 °C,respectively. The sample calcined at 600 °C(NT600) acquires the highest percentage of nitrogen element due to its open pore structure that facilitates the diffusion of nitrogen during calcination. Raman intensity depends on the amount of nitrogen doping, thus NT600 exhibited the best SERS activity. The doped nitrogen in TiO_2 facilitates the charge transfer between TiO_2 and probing molecules and thus suppresses the electron–hole recombination. This work provides a new perspective on the design of efficient TiO_2 SERS active substrate and is expected to be valuable for adsorbate detection on semiconductor surface.     

The effect of copper valence on catalytic combustion of styrene over the copper based catalysts in the absence and presence of water vapor☆

Catalysts Cu Ox/γ-Al_2O_3-IH and Cu Ox/γ-Al_2O_3-IM were prepared, characterized, and tested for styrene combustion in the absence and presence of water vapor. The effect of copper valence of the catalysts on the catalytic activity for styrene combustion was discussed using the theory of hard soft acids and bases(HSAB).The results showed that the existence of water vapor in feed stream inhibited the catalytic activity for styrene combustion due to the competition adsorption of water molecule. HSAB theory confirmed that the local soft acidity of the catalyst Cu Ox/γ-Al_2O_3-IH was much stronger than that of the catalyst Cu Ox/γ-Al_2O_3-IM because of the higher content of soft acid Cu+on its surface, which increased the adsorption ability toward soft base of styrene and reduced the adsorption toward hard base of water vapor, and thus increased the catalytic activity for styrene combustion and weakened the negative influence of water vapor.     

Location choice of Chinese urban fringe residents on employment,housing, and urban services: A case study of Nanjing

Urban fringe area is the most important space for city development. It includes several complicated elements, such as population, space, and management organization. On the basis of local population attributes in the city fringe area combined with people’s movement characteristics in time and space, this article reclassifies basic public service facilities and discusses the relationship between facility layout and housing, employment, and commuter transportation. Through a questionnaire survey in Qiaobei District of the urban fringe area in Nanjing and on the basis of comparative analysis, we discuss the impact factor on the choice of housing, urban services, and the tolerance of commuting time. Our findings indicate mutual promoting and restricting connections among living, employment, and services. Workers’ living situation determines their daily behavior, such as dining, shopping, and entertainment. Furthermore, different income levels have a great influence on residents’ choices with regard to places to live and develop their careers     

Preparation of vanadium-based electrode materials and their research progress in solid-state flexible supercapacitors

Solid-state flexible supercapacitors(SCs) have many advantages of high specific capacitance,excellent flexibility,fast charging and discharging,high power density,environmental friendliness,high safety,light weight,ductility,and long cycle stability.They are the ideal choice for the development of flexible energy storage technology in the future,and provide a good prospect for energy storage applications.At present,solid-state flexible SCs are widely used for portable electronic equipment and we...     

PLA／LLDPE共混体系反应性增容研究

在聚乳酸(PLA)中加入线性低密度聚乙烯(LLDPE)进行增韧,并通过相容剂LLDPE接枝甲基丙烯酸缩水甘油酯-苯乙烯共聚物[LLDPE-g-(GMA-co-St)]和弹性体乙烯-甲基丙烯酸-甲基丙烯酸缩水甘油酯(E-MA-GMA)增容PLA和LLDPE.用红外光谱、动态流变和SEM对共混物进行了表征,测试了共混物的力学性能.结果表明,LLDPE-g-(GMA-co-St)和E-MA-GMA的加入都能明显提高PLA/LLDPE的冲击韧性,起到了反应性增容的作用,使共混体系的分散相尺寸明显减小,分布均匀,共混物的动态损耗模量G"增加.与LLDPE-g-(GMA-co-St)相比,加入E-MA-GMA的共混物中分散相粒径更加细微.     

基于多目标的数控铣镗床床身优化研究

为了提高某大型数控铣镗床床身的性能,运用现代设计方法对该床身结构的设计变量进行了多目标优化。在分析床身结构特点的基础上,以质量和一阶固有频率为目标建立了床身结构优化数学模型,在Pm／E中实现床身结构三维模型的全参数化建模,应用主要目标法将多目标数学模型转化为单目标数学模型,使用ANSYS Workbench软件对转化后的数学模型进行了优化计算,优化计算结果有效地减轻了床身质量,提高了床身的一阶固有频率。     

Effect of pH on N₂O reduction and accumulation during denitrification by methanol utilizing denitrifiers

Acidic pH has previously been found to increase nitrous oxide (N₂O) accumulation during heterotrophic denitrification in biological wastewater treatment. However, the mechanism of this phenomenon still needs to be clarified. By using an enriched methanol utilizing denitrifying culture as an example, this paper presents a comprehensive study on the effect of pH (6.0-9.0) on N₂O reduction kinetics with N₂O as the sole electron acceptor, as well as the effect of pH on N₂O accumulation with N₂O as an intermediate of nitrate reduction. The pH dependency of nitrate and nitrite reduction was also investigated. The maximum biomass-specific N₂O reduction rate is higher than the corresponding maximum nitrate and nitrite reduction rates in the entire pH range studied. However, the maximum biomass-specific N₂O reduction rate is much more sensitive to pH variation outside of the optimal range (pH 7.5 to pH 8.0) than the maximum biomass-specific nitrate and nitrite reduction rates. The half-saturation coefficient of the N₂O reductase increased from 0.10 mg N₂O-N/L to 0.92 mg N₂O-N/L as pH increased from pH 6.0 to 9.0. At pH 6.0, approximately 20% and 40% of the denitrified nitrate accumulated as N₂O in the presence and absence of methanol (as an exogenous carbon source), respectively. However, at pH 6.5, these fractions decreased to 0% and 30%, respectively. No N₂O accumulation occurred at pH 7.0 to 9.0 independent of the availability of methanol. These results suggest that the competition for electrons among different nitrogen oxides reductases likely plays a role in N₂O accumulation at low pH conditions.