Charge transport and luminescent properties of PMMA-dehydrate nanotubed titanic acid nanocomposites

In this paper, we doped p-type conductivity dehydrated nanotubed titanic acid (DNTA) into insulator polymer poly(methyl methacrylate) (PMMA). The electric properties of this nanocomposite were investigated. The photoluminescence efficiency of fluorescent dye 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) in PMMA matrix was enhanced by doping with DNTA. Moreover, screen effect by DNTA with high permittivity caused the emission from DCJTB to be blue-shifted.     

Sustainability assessment and decision making of hydrogen production technologies: A novel two-stage multi-criteria decision making method

A novel two-stage multi-criteria decision making (MCDM) method is proposed with the aim to select the most sustainable hydrogen production technology (HPT) by considering the preference information on both attributes and alternatives. In the first stage of the method, the initial sustainability ranking of the alternative HPTs was achieved by using the FBWM (Fuzzy Best-Worst Method) to determine the weights of the criteria and the fuzzy TOPSIS (Technique for Order Performance by Similarity to Ideal Solution) method to prioritize the sustainability of alternative HPTs. While, in the second stage, a novel Preference Ranking Linear Programming Method (PRLPM) was used to acquire the final sustainability ranking according to the alternative preference information by following the principle of the outranking method. The proposed method was illustrated by a case study with 8 HTPs, demonstrating that the developed two-stage MCDM method can reflect the alternative preference of the decision-maker more accurately for selecting the most preferred alternative among various HTPs.     

The spectral characteristics of dissolved organic matter from sediments in Lake Baiyangdian,North China

Dissolved organic matter (DOM) extracted from sediment samples in Lake Baiyangdian was investigated using UV -Vis absorption and fluorescence spectroscopy. Two parameters, the ratios of absorbance and dissolved organic carbon at 254° nm (SUVA₂₅₄) and the integral area from 240° nm to 400° nm (A_{240 -400}), were used to assess the molecular weight and aromaticity of DOM. The surface sediments showed a relatively low aromaticity of DOM due to the impact of environmental pollution. Synchronous fluorescence spectra showed an extremely high fraction of the protein-like region (PLR). Parallel factor analysis (PARAFAC) of excitation -emission matrix spectra revealed four fluorescent components occurring in sediment DOM: two humic-like (C1 and C2) components and two protein-like (C3 and C4) components. The PARAFAC-PCA displayed three PCA factors (factors 1, 2 and 3) which accounted for 48.250%, 25.927% and 25.391%, respectively, of the variance in fluorescent component. The humic-like components 1 and 2 concurrently showed positive factor 1 loadings. Factor 2 was mainly explained by the tryptophan-like component C3. A non-humic component 4, having a low factor loading in the other two factors, showed an extremely high factor 3 loading. The EEM -PARAFAC-PCA showed varying contributions of terrestrial versus autochthonous DOM sources in lake sediments.     

基于Visual C[KG-*2]+[KG-*2]+的化学品泄漏事故信息数据库

随着数据库技术的飞速发展和广泛应用,其高效快捷的操作方式逐步取代了传统的纸质管理.本文针对当前频发的化学品泄漏事故,建立化学品泄漏事故信息数据库,从化学品生产及储存、化学品性质、水基础设施、化学品泄漏事故及结果预测方面分析数据库的组成,以Visual C++ 6.0和SQL Server 2000数据库作为开发平台,采用ODBC技术对数据库进行访问,实现了对化学品泄漏事故信息数据库的查询、添加、修改、删除及图片查看等功能,初步应用表明开发的数据库具有安全性、实用性及可扩展性.     

Equilibrium theory revisited. Isothermal fixed-bed sorption of binary systems-II. Non-Langmuir solutes with type I parent isotherms: Azeotropic systems

The preceding analysis of the equilibrium percolation of binary Langmuir solutes (Part I) is extended to systems with arbitrary equilibrium relations and parent isotherms of Type I. The use of “extended” binary Langmuir isotherms is proposed as the best means for providing some analytical insight while satisfying important thermodynamic and mathematical requirements.We show that the simple method for locating the watershed point given in Part I can be extended to broad classes of parent solute isotherms. It consists of determining, analytically or graphically, the intersection of the light component Henry's line with the heavy component isotherms. This opens up a rapid path for assessing the effectiveness of displacement agents in purging a loaded bed and achieving high levels of desorbate enrichment (see Part III).The behaviour of binary non-Langmuir solutes, both with and without selectivity reversal is addressed. The latter case yields solute trajectories and other properties which resemble, in all major aspects, those established for Langmuir solutes (Part I). It is shown that under certain conditions minor changes in the equilibrium parameters can lead to serious aberrations in the predicted solute trajectories. The use, in particular, of single component isotherms to represent strongly sorbed solutes yields highly erroneous predictions of binary desorption and displacement processes.The effect of selectivity reversal is expressed through azeotropic loci, incorporated in the hodograph diagrams. These curves constitute deflecting barriers in some cases and can be traversed by the solute trajectories in others. The distinguishing feature of the hodographs is the shape of the negative characteristics in q-Y space which inflect across a diagonal in much the same way as binary vapour-liquid azeotropes. The resulting solute fronts still follow the binary Langmuir pattern in most instances, except in certain displacement operations and in cases of simultaneous azeotropic propagation. The inflecting form of the Γ⁻ characteristics also gives rise to the interesting possibility of isolating pure gaseous solute fractions from a binary feed through the use of dual column systems operated at different total pressures.Various solute pathways, created by the presence of the azeotropic curves are analyzed, and compared with experimental column breakthrough curves. The extreme sensitivity of certain azeotropic pathways to the precise form of the equilibrium relation is discussed.     

人工湿地植物生长特性及其对氮磷富集能力研究

采用室外盆栽实验研究了香蒲和梭鱼草两种湿地植物的生长特性及其对富营养化水体中氮、磷的吸收富集能力,为深入研究湿地植物在污水处理中的作用提供依据。实验期间,香蒲和梭鱼草均能在富营养化水体中正常生长,经过5个月的生长,两种植物的总生物量分别为6.65 kg/m2和10.83 kg/m2,约为栽种前的6倍和7倍。实验前,香蒲和梭鱼草根、茎、叶中TN的分布为叶>根>茎;TP在两种湿地植物组织中的分布均为叶>茎>根。实验结束后,香蒲和梭鱼草各组织中的TN、TP含量均明显下降,TN在梭鱼草组织中的分布仍为叶>根>茎,而香蒲组织中TN分布为根>叶>茎;两种植物组织中的TP分布为根>叶>茎。比较而言,梭鱼草具有较高的氮、磷积累量。     

基于BP网络的人工沉床系统水质净化效果研究

人工沉床技术是一种新兴的生物-生态水体原位修复技术,水质净化过程具有非线性与不确定性,传统方法建立的数学模型难以精确模拟。本文以天津市外环河人工沉床实验2007年10月至2008年9月的水质实测数据为基础,建立BP神经网络水质模型,并与多元非线性回归方法进行比较。结果表明:建立的BP人工神经网络模型对不同水质指标拟合的平均相对误差分别为:化学需氧量(CODCr)0.1%,总氮(TN)1%,总磷(TP)0.6%。与多元非线性回归的拟合结果相比,平均相对误差更小,BP神经网络模型更适用于人工沉床系统出水水质的模拟。