Use of chemometrics methods and multicriteria decision-making for site selection for sustainable on-site sewage effluent disposal

This paper presents a study undertaken to evaluate site suitability for sewage effluent renovation based on physico-chemical characteristics of the soil. The results obtained showed that as the soil becomes acidic, the phosphorus concentration in the soil reduces accordingly. The chloride ion concentration was found to be a reliable indicator for evaluating the soil capacity to remove nitrogen. A high cation exchange capacity (CEC) can enhance the renovation of sewage effluent. Soils with high quartz content had a low CEC with high organic matter content (OM) being able to compensate. Therefore, an understanding of the micro-nutrients in the soil, organic matter content and chloride ion concentration are important.To facilitate a multi-variate approach for site selection, multicriteria decision-making (MCDM) methods, PROMETHEE and GAIA, were applied for analysis of a sequence of three matrices consisting of 8, 16, and 48 soil site objects, respectively, and seven soil property parameters. Matrix models and the interpretation of results are discussed in detail. From these analyses, PROMETHEE II net outranking flows, ?, found that two sites were always among the top three ranks of the three matrix models, which suggested that they were the most suitable for sewage effluent renovation. The criteria CEC and OM, were particularly important for the selection of these better sites, but pH and Cl⁻ attributes discriminated the weaker performing sites from the better ones; as well the PO₄³⁻ and the NH₃-N criteria were in general opposition to CEC, OM, pH and Cl⁻ but were much less effective as discriminators. Consideration of net outranking flows suggested an approach method for the selection of other possibly suitable sites for sewage effluent renovation.     

PVC/EVA/SBS共混体系研究

利用溶液成膜法制备了PVC/SBS薄膜 ,对其表观形态、力学性能进行了研究 ,并讨论了EVA对体系的增容作用。发现EVA在一定浓度范围内能增加PVC与SBS的相容性 ,提高断裂伸长率 .测量了溶液的相对粘度 ,得出了相反转浓度点。     

Modification,degradation, and stability of polymeric surfaces treated with reactive plasmas

The degradation, modification, and stability of polymeric surfaces exposed to chemically reactive O₂ and H₂O‐vapor plasmas were investigated. Specifically, the effects of these plasmas on etching rate, surface morphology, wetting instability, and fluid‐holding capability were studied. Wetting instability is reflected by hydrophobic recovery and can be examined by the Wilhelmy balance method. Although hydrophobic recovery is usually attributed to surface configuration change, there are actually two types: reversible and permanent. Reversible hydrophobic recovery is caused by surface configuration change, whereas permanent hydrophobic recovery is caused by the creation of oxidized surface oligomers. This study distinguishes the two by identifying differences in the shapes of the corresponding Wilhelmy force loops and in the fluid‐holding parameter. The presence of surface oligomers was most detrimental to wetting stability and fluid‐holding capability but could be controlled via the type of reactive gas, the discharge conditions, and the polymer substrate. In general, polymers most susceptible to O₂‐plasma etching had the least surface oligomers and vice versa, whereas H₂O‐vapor plasma suppressed surface oligomers on polymers less susceptible to etching. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3028–3042, 2000     

Sensible design of open-porous spherical architectures for hybrid supercapacitors with improved high-rate capability

Hybrid supercapacitors show high energy densities with good long-term cycling stability when used as energy sources. However, their poor rate performance as a consequence of their low ionic diffusion capability at high currents during cycling should be improved. Here, we propose using a spray-drying process to fabricate a novel structure comprising open-porous spherical lithium manganese oxide as an electrode material for hybrid supercapacitors. The resultant hybrid supercapacitor comprising full-cell systems shows a high specific capacitance (33.8 F cm⁻³ at a current of 1 A) and remarkable high-rate performance (25.6 F cm⁻³ at a current of 16 A). Moreover, outstanding cycling stability of 83% was attained at a current of 2 A after 5400 cycles. Our new strategy provides a useful methodology to increase the abundance of electrochemically active sites by fabricating a spherical structure using nanosized primary particles, which also leads to shorter diffusion pathways and to improved ionic electron transport because of the open-porous structure of the electrode materials.     

Li4SiO4对CO2捕集性能的实验研究

以Li₂CO₃和SiO₂为原料,通过高温固相合成法合成了CO₂捕集剂Li₄SiO₄,并用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)对所合成的材料在CO₂捕集前后的晶相变化以及微观结构进行了表征。通过热重分析仪(TGA)研究了Li₄SiO₄材料吸附CO₂的性能,并在小型热态实验台架上进行了CO₂热态捕集实验。实验结果表明,Li₄SiO₄对CO₂的捕集性能受Li₄SiO₄合成温度、CO₂的吸附温度以及气体中CO₂含量的影响,在700 ℃下制得的Li₄SiO₄具有最佳的CO₂吸附特性,最大吸附增量可达34%。Li₄SiO₄的吸附能力随着CO₂含量和吸附时间的增加而增加,当CO₂浓度分别为75%、67%、60%时,700 ℃ Li₄SiO₄对CO₂最大吸附量分别可达6.68 mmol/g、3.37 mmol/g、2.02 mmol/g (理论量8.33 mmol/g)。     

新型Li4Ti5O12@石墨烯的微波辅助合成及电化学性能研究

将钛酸四丁酯和氧化石墨超声分散于叔丁醇,微波辐射下加入醋酸锂溶液制备尖晶石Li₄Ti₅O₁₂（LTO）前驱体/氧化石墨烯。一方面,微波作用促进了钛酸四丁酯水解,前驱体的形成能在15min内完成。另一方面,叔丁醇的“软模板”限域作用导致形成粒子极小且形貌单一的LTO前驱体。同时,细小的LTO前驱体粒子通过二次团聚将氧化石墨烯纳米片完全包埋。最后,LTO前驱体/氧化石墨烯在800℃下煅烧8h得到尖晶石LTO@石墨烯（LTO@G）。研究表明,LTO@G晶体尺寸在0.2~1.5μm之间,其振实密度达到1.7g·cm^-3。石墨烯位于晶体内部,并显著提高了材料的电子传导性。LTO@G的电导率为1.84×10^-3S·m^-1,远高于纯相LTO（1.1×10^-7S·m^-1）。1C和4C下,LTO@G首次充放电容量分别是170.1和97.5mAh·g^-1。可见,LTO@G具有高倍率性能和振实密度,可广泛应用于各种商品锂离子电池。     

Determination of quinolones by fluorescent excitation emission

In this work the viability of a fluorescent technique for the determination of quinolones is studied. This analytical technique allows one to analyze the effect of the increasing order of the analytical signal from a univariate calibration (zero order data) to partial least squares (PLS) calibration (first order). The comparison has been done through the figures of merit of the analytical procedure (technique and calibration) in accordance with the ISO norm and the 2002/657/EC European Decision about residuals.     

Numerical Determination of Damping in Metal Matrix Composites

Damping in metal matrix composites is mainly caused by inelastic matrix deformation induced by the great difference in the mechanical properties of the single constituents of the materials. In this study, the finite-element method in combination with a highly accurate material model is employed to examine the effects of both the fiber volume fraction and the external loading amplitude on the energy dissipation process in an Al/SiC composite under a cyclic mechanical load.     

回填材料膨润土对放射性气体滞留能力模拟研究

利用各种分析手段对膨润土的物理特性进行了表征.X射线衍射分析表明钠基膨润土呈典型的六方晶胞,晶胞参数是: a轴4.913, c轴5.405;差热分析曲线在低温区和高温区有明显的吸热峰出现;元素分析钠、钾离子的含量大于钙、镁离子的含量,在性能上表现为钠质膨润土具有较强的离子交换能力;显微分析表明其表面呈皱隙状,测定比表面积高达24.52 m2/g;吸水率测定表明膨胀率大,说明它具有密封功能,可有效阻滞地下水的渗入.利用SF6示踪技术,通过采集不同时间段取样池样品,分析样品中示踪气体浓度,绘制取样池示踪气体浓度随时间的变化关系曲线,根据费克扩散定律计算扩散系数.实验结果表明,随着压实膨润土密度的增大,示踪气体扩散系数迅速减小,当密度大于1.8 g/cm3时,扩散系数降至10-9 m2/s.研究结果表明,膨润土性能优化是通过在膨润土中添加适量的活性炭,可明显改善其对气体的阻滞能力;增加其对放射性气体滞留能力;添加少量的石英砂增加其机械性能、导热性和减少蠕变性,将引起对气体阻滞能力的下降.综合考虑,在膨润土中各添加5%活性炭和石英砂,既对气体具有较好的滞留能力,又具有较好的工程特性.     

NbSe2纳米材料的合成及减摩性能研究

将Se粉和Nb粉按一定的比例混合,然后密封在石英管中或压成片状后密封于石英管中,加热到一定温度,分别获得了NbSe2纳米纤维和NbSe2纳米颗粒.采用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)对所得产物进行了表征,分析了其微观形貌;采用MS-T3000摩擦磨损试验机测定了纳米颗粒作为基础润滑油N40添加剂的摩擦学性能.结果表明,制备的纳米纤维直径100～200nm,纳米颗粒直径40～300nm,二者都具有层状结构和良好的结晶性;NbSe2纳米颗粒作为润滑油添加剂具有明显优于基础润滑油的极压减摩性能;同纳米纤维相比,纳米颗粒的减摩性能较好.