Chemometric investigations on environmental data from Carlo Alberto irrigation canal (Alessandria,Piedmont, Italy)

The Carlo Alberto Canal connects Bormida and Tanaro rivers in Piedmont (ITALY). It was created for irrigation purposes but since its waters are suspected to be polluted, a sampling campaign was performed by the ARPA of Alessandria. The physico-chemical parameters analysed along 3 years (1998-2000) were investigated by multivariate chemometric methods. PCA showed that the waters situation depends heavily on the sampling period. Also a Kohonen self-organising map confirmed the clustering observed, providing insights into the causes of the clusterisation. New samplings are now being performed and a larger set of environmental variables is determined on each sample.     

Sea water contamination in underground waters of salento (Southern Italy)

In the present work, a study of a physico-chemical characterisation of underground waters, utilised for agriculture and human use in the Lecce district (Southern Italy) has been reported. The aim of the work has been to define the quality of underground waters in the different areas and to value salt contamination due to seawater intrusion. Statistical techniques, such as Principal Component Analysis (PCA) and Cluster Analysis (CA), have been utilised to examine the correlations among the different parameters and to define contamination areas. The results have shown a high salt contamination in artesian wells of the Ionian Sea coast.     

Underground waters quality in the province of Lecce (Apulia, Southern Italy)

This paper shows the results of underground waters last monitoring in the province of Lecce (Apulia, Southern Italy). We carried out the physical-chemical characterization of the aquifers and their classification in accordance to limit values sanctioned by Italian legislation in force, by European directives and by FAO, in order to define their quality and to establish their possible use for drinkable and irrigation purposes. The attention has been focused on salinity evaluation and underground waters contamination phenomena, due to sea-water intrusion and to the use of fertilizers. Salinity and nitrates concentrations are high in a few wells. Iron and manganese concentrations are very high for almost every sample and this is due to corrosion phenomena of artesian wells metallic structure. For a better interpretation of data, multivariate statistical analysis has been used, in order to obtain the correlation among analytical results, soils hydro-geological properties and anthropic conditions.     

Enzyme classification using multiclass support vector machine and feature subset selection

Proteins are the macromolecules responsible for almost all biological processes in a cell. With the availability of large number of protein sequences from different sequencing projects, the challenge with the scientist is to characterize their functions. As the wet lab methods are time consuming and expensive, many computational methods such as FASTA, PSI-BLAST, DNA microarray clustering, and Nearest Neighborhood classification on protein–protein interaction network have been proposed. Support vector machine is one such method that has been used successfully for several problems such as protein fold recognition, protein structure prediction etc. Cai et al. in 2003 have used SVM for classifying proteins into different functional classes and to predict their function. They used the physico-chemical properties of proteins to represent the protein sequences. In this paper a model comprising of feature subset selection followed by multiclass Support Vector Machine is proposed to determine the functional class of a newly generated protein sequence. To train and test the model for its performance, 32 physico-chemical properties of enzymes from 6 enzyme classes are considered. To determine the features that contribute significantly for functional classification, Sequential Forward Floating Selection (SFFS), Orthogonal Forward Selection (OFS), and SVM Recursive Feature Elimination (SVM-RFE) algorithms are used and it is observed that out of 32 properties considered initially, only 20 features are sufficient to classify the proteins into its functional classes with an accuracy ranging from 91% to 94%. On comparison it is seen that, OFS followed by SVM performs better than other methods. Our model generalizes the existing model to include multiclass classification and to identify most significant features affecting the protein function.     

Real-time instrumentation for monitoring water quality: An Australian perspective

Current research in the field of real-time monitoring of water quality is reviewed from an Australian perspective. The desirable features of continuous monitoring instruments and progress in developing multi-parameter real-time instruments are considered first. Then Australian R&D in the three main areas involved in developing a complete instrument are considered; these are sample preparation and handling, new sensors and sensing chemistry, and finally data capture, processing and display. The review identifies five areas where developments are needed: new methods for handling and processing ‘real’ (i.e. ‘dirty’ and heterogeneous) samples; the development of new sensors to provide more detailed information on particular forms (e.g. bioavailable) of contaminants; new sensors for detecting and quantifying the presence of low concentrations of toxic organic compounds in natural waters; new real-time methods for assessing the microbial quality of waters; and greater use of chemometrics in processing the signals obtained from complex sample matrices.     

Evaluation of groundwater quality within a typical Egyptian village, North of Cairo, Egypt

Groundwater is the second most abundant water resource in Egypt, 2/3 of which is consumed within the Nile Delta Region and the valley. However, with recent intensification of agricultural and urbanizing activities over the past 40 years, the water quality in the Nile basin aquifer has significantly deteriorated. The objective of this study is to survey the variation in the groundwater quality tapped within a typical Egyptian village located in the valley, north of Cairo, from January until April 2000. Results revealed that locations close to agricultural lands reflected an increase in the TDS, ammonia, nitrates, chlorides and sulfates contents as a implication of vertical and side infiltration of multiple pollutants. In addition, locations within residential quarters recorded significant BOD and COD concentrations, reflecting a significant organic matter intrusion at these wells. Multivariate analysis for the January data indicated that agricultural activities had a greater impact on these waters causing an overall increase in TDS and EC contents. However, with the increase in Nile surface water flow during April, there was an increase in fresh water infiltration within this area, which helped to reduce the TDS, EC and other inherent ionic constituents of these waters.     

From interpenetrating polymer networks to hierarchical porous carbons for advanced supercapacitor electrodes

A novel and effective strategy to fabricate hierarchical porous carbons for supercapacitors is developed via in-situ activation of interpenetrating polymer networks obtained from simultaneous polymerization of the monomers for two polymeric networks.     

Characterization of Sediments in Aerated Lagoons and Waste Stabilization Ponds

Abstract

Sediments affect the performance of aerated lagoons and waste stabilization ponds in many ways. This paper presents the results of a three years study conducted on real-size facilities and implementing numerous analytical procedures. Sediment accumulation rates and physico-chemical characteristics are described as well as their activity in terms of oxygen consumption and exchange rates with overlying waters.

The deposits had a mean accumulation rate of 4.7 cm per year, their main characteristics being low viscosity and high organic content (>30%). They also accumulated numerous organic and mineral compounds, such as nutrients and heavy metals. Vertical concentration profiles, measured in the sediment and interstitial liquid phases, are presented and discussed. These results emphasize the importance of surface activity.

Sediment oxygen demand, which can be divided into biological and chemical components, ranged from 1 to 3 gO₂/m²·d. Finally, the exchange rates of COD, nitrates, ammonia and orthophosphates existing at sediment-water interface were quantified under several redox conditions and substrate additions.     

Liquid chromatography-tandem mass spectrometric analysis and regulatory issues of polar pesticides in natural and treated waters

Pesticides are among the most detected contaminants in the aquatic environment. This is mainly due to their use in agriculture and their physico-chemical properties that enable transportation and a persistent or pseudo-persistent existence in the water media. Several directives and guidelines set maximum levels of pesticides in water in order to protect the human and environmental health. A brief discussion of the existing directives and guidelines concerning pesticides in water is presented, e.g., the new regulatory framework for the Registration, Evaluation and Authorisation of Chemicals (REACH), and the Directive 91/414/EEC concerning the placing of plant protection products on the market. Up-to-date analytical tools to support the REACH program are of prime importance to ensure its complete implementation. Since liquid chromatography (LC) coupled to mass spectrometry (MS) is considered the most appropriate technique for determination of most modern pesticides in environmental waters, the most recent developments and applications in this field are discussed in detail in this review.     

Environmetrical Treatment of Water Quality Survey Data from Yantra River, Bulgaria

 The environmetrical analysis carried out has indicated that the short-term water quality survey may give a very important information on the latent factors influencing the water quality of Yantra river basin. The principal components analysis carried out reveals that at least four principal components are necessary for multivariate statistical modeling of the water quality – combination of natural and anthropogenic influences (“mixed” factor) reflecting parameters such as water hardness, marine influence, organic pollution; typical anthropogenic influences (“anthropogenic” factor) explaining the metal contamination of the river water; everyday wastes, usually N-containing pollutants such as nitrates, nitrites or ammonia, form the “N-containing wastes” factor and a “temperature” factor formed by typical physical parameters such as water and air temperature. The formation of these special features of the river waters from Yantra basin is also confirmed by the results of cluster analysis (variable clustering) where the content of the significant clusters of the variables is the same as the content of the principal components modeling over 75% of the total variance of the system. Additionally, the cluster analysis of the objects has proved that the water quality during both sampling traverses is very stable and reproducible. Few exceptions are observed due to momentary local pollution in an industrial area along the river stream. Comparison with standard requirements for water quality has indicated that the Yantra river waters are of high quality and could be used after minor pretreatment as potable water sources. The environmetrical approaches applied reveal a specific information concerning the river water quality. In this way the ecological problem treated has not a local importance but suggests a strategy for estimation of similar ecosystems in global sense. Received July 30, 1998. Revision June 1, 1999.     

半夏中微量元素的测定及半夏模糊聚类分析

采用原子吸收分光光度法测定了20个不同产地半夏样品中Fe,Mn,Cu,Zn,Cr,Ca,Mg,Ni,Pb等9种元素的含量。由于不同产地的半夏中微量元素含量数据离散,根据一种或几种微量元素的含量难以评价药物的相似性,故以9种元素含量并结合Zn/Cu值和Ca/Mg值为指标,运用模糊聚类分析方法研究半夏药物的质量分类。结果显示,当阈值λ=0.55时,20个半夏样品聚为4类;当λ=0.65时,20个半夏样品聚为6类;当λ=0.70时,20个半夏样品聚为10类。半夏中微量元素含量丰富,微量元素的种类及含量与药物疗效密切相关。在高阈值λ上截取聚为一类的药物其组成与质量相似性较大,该研究为中药质量评价提供了一种新的方法。     

Source Apportionment for the Zinc—Containing Component of Air Particulate Matter using Automated Electron Probe Micro Analysis of Individual Particles

Abstract

A methodology is described for the apportionment of zinc-containing particulate matter sampled in the vicinity of a zinc smelter to their corresponding sources in the factory. Bulk samples of particulate matter from six potential emission sources were analysed by automated electron probe microanalysis (EPMA) in order to characterize the individual particles. Based on a data set of relative peak intensities and with the aid of a binary clustering method, the most important particle classes were identified. They were used as a basis for the development of a set of disjunct identification rules (decision rules), which were able to describe the classes in a unique manner. Applying these rules upon ambient particulate data enabled the estimation of relative contributions of different types of zinc-containing particles. Evidence was found that a large number of particles was modified by a soil component or by gas phase reactions.     

New organic nitrates. I. Synthesis of 1,3-benzoxazine-2,4-dione, 1,3-benzoxazine-2-thion-4-one, 1,3-benzothiazine-2,4-dione and quinazoline-2,4-dione derivatives

The preparation and the physico-chemical characterization of new heterocyclic organic nitrates containing 1,3-benzoxazine-2,4-dione, 1,3-benzoxazine-2-thion-4-one, 1,3-benzothiazine-2,4-dione and quinazo-line-2,4-dione moieties, are reported.     

钇对石墨烯储氢性能的影响

应用基于密度泛函理论的第一性原理方法研究过渡金属钇（Y）修饰对石墨烯储氢性能的影响。考虑Y原子在石墨烯上易形成团簇,采用B原子掺杂有效阻止了团簇形成。通过模拟计算得到的改性体系稳定、储氢性能优异,可吸附6个H₂分子,平均吸附能范围为-0.539到-0.655 eV （per H₂）,理论上满足理想的氢吸附能范围。经Bader电荷初步计算和基于Y/B/graphene （G）体系吸附H₂分子的电子态密度及电荷差分密度图分析得,Y原子与石墨烯间通过电荷转移产生结合,与H₂分子则发生典型的Kubas型相互作用。Y原子改变了H₂分子与石墨烯基的电荷分布,成为连接两者电子云的桥梁,从而增强了H₂分子的吸附能。改性石墨烯体系吸附的均为氢分子,有利于在环境温度和压力条件下进行循环控制,是具有良好发展前景的储氢材料之一。     

Determination of the van der Waals, electron donor and electron acceptor surface tension components of static Gram-positive microbial biofilms

A large number of studies have shown the influence of the physico-chemical properties of a surface on microbial adhesion phenomenon. In this study, we considered that the presence of a bacterial biofilm may be regarded as a “conditioning film” that may modify the physico-chemical characteristics of the support, and thus the adhesion capability of planktonic micro-organisms coming into contact with this substratum. In this context, we adapted a protocol for biofilm formation that allows, under our experimental conditions, contact angle measurements, the reference method to determine the energetic surface properties of a substratum. This made it possible to determine the van der Waals, electron acceptor and electron donor properties of static biofilms grown at 25°C on stainless-steel slides with six Gram-positive bacteria isolated in dairy plants. A variance analysis indicated significant effects (P<0.05) of the bacterial strains and of the physiological state of the micro-organisms (planktonic or sessile) on the contact angles. To link the energetic properties of the six biofilms with direct adhesion experiments, we measured the affinity of fluorescent carboxylate-modified polystyrene beads for the different biofilm surfaces. The results correlated best with the electron-acceptor components of the biofilm surface energies, stressing the importance of Lewis acid–base interactions in adhesion mechanisms.     

Separation, detection and occurrence of (C2–C8)-alkyl- and phenyl-alkyl nitrates as trace compounds in clean and polluted air

Nitric acid, HNO₃, and nitrous acid, HNO₂, are forming stable esters with alcohols, the alkyl nitrates and alkyl nitrites. Both groups of compounds are used as fuel additives, explosives and pharmaceuticals. Alkyl nitrates are also formed as complex mixtures during incomplete combustion and the abiotic transformation of alkanes, alkenes and aldehydes in air. Organic nitrates can be assigned to anthropogenic and natural sources alike. Here the synthesis of reference mixtures of alkyl nitrates is described starting with alcohols, alkyl bromides, alkyl iodides or alkanes, respectively, sampling techniques in air analysis, and the separation of alkyl nitrates and alkyl dinitrates by high resolution capillary gas chromatography using various stationary phases and electron capture (HRGC/ECD) as well as mass spectrometric detection (HRGC/MSD). A highly selective detection mode for alkyl nitrates and alkyl di- and trinitrates — in general in the presence of other organic trace compounds — is the single ion monitoring of 46 amu in GC/MS. The separation and occurrence of alkyl- and phenyl-alkyl nitrates in polluted air is reported using capillary gas chromatography with electron capture and ion trap MS detection. The reaction of alkanes with nitric acid at room temperature simulates in a good approximation the pattern of alkyl nitrates formed in air chemistry.     

The effect of structural redundancy in validation sets on virtual screening performance

The performance of a classification model is often assessed in terms of how well it separates a set of known observations into appropriate classes. If the validation sets used for such analyses are redundant due to bias in sampling, the relevance of the conclusions drawn to prospective work in which new kinds of positives are sought may be compromised. In the case of the various virtual screening techniques used in modern drug discovery, such bias generally appears as over‐representation of particular structural subclasses in the test set. We show how clustering by substructural similarity, followed by applying arithmetic and harmonic weighting schemes to receiver operating characteristic (ROC) curves, can be used to identify validation sets that are biased due to such redundancies. This can be accomplished qualitatively by direct examination or quantitatively by comparing the areas under the respective linear or semilog curves (AUCs or pAUCs). Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of trace elements and their physico-chemical forms in natural waters

Trace elements in natural waters can be present in different physico-chemical forms, varying in size, charge and density properties. Knowledge of speciation is essential for understanding the transport, distribution, and biological uptake of trace elements in the environment. The development of techniques to provide reliable information on physico-chemical forms has, therefore, become a challenge within Analytical Chemistry.When selecting analytical methods for the determination of total concentrations or fractions of trace elements in natural waters, no exclusion of species should occur, or at least it must be accounted for. Furthermore, the determination limits must be sufficiently low to allow the actual concentrations to be determined with reasonable precision and accuracy. For very low concentrations, preconcentration techniques are applicable, provided the chemical yield of the spike represents that of the original species present. For methods meeting these criteria, the suitability for routine analysis should be considered.When the physico-chemical forms of trace elements are to be determined, the fractionation should take placein situ or shortly after sampling. As the concentrations involved in speciation studies may be extremely low, there is an increasing awareness of potential sources of errors influencing analytical results. Sample collection and separation/fractionation/concentration procedures prior to analysis are, therefore, essential within Analytical Chemistry, and the whole procedure must be taken into account when interpreting the results. There are, however, several requirements which should be met by techniques applicable for speciation purposes. In general, size fractionation techniques (e.g.in situ hollow fibre ultrafiltration) should be applied prior to the addition of any chemical reagents (charge fractionation techniques).     

Geometric similarity between protein–RNA interfaces

A new method is described to measure the geometric similarity between protein–RNA interfaces quantitatively. The method is based on a procedure that dissects the interface geometry in terms of the spatial relationships between individual amino acid nucleotide pairs. Using this technique, we performed an all‐on‐all comparison of 586 protein–RNA interfaces deposited in the current Protein Data Bank, as the result, an interface–interface similarity score matrix was obtained. Based upon this matrix, hierarchical clustering was carried out which yielded a complete clustering tree for the 586 protein–RNA interfaces. By investigating the organizing behavior of the clustering tree and the SCOP classification of protein partners in complexes, a geometrically nonredundant, diverse data set (representative data set) consisting of 45 distinct protein–RNA interfaces was extracted for the purpose of studying protein–RNA interactions, RNA regulations, and drug design. We classified protein–RNA interfaces into three types. In type I, the families and interface structural classes of the protein partners, as well as the interface geometries are all similar. In type II, the interface geometries and the interface structural classes are similar, whereas the protein families are different. In type III, only the interface geometries are similar but the protein families and the interface structural classes are distinct. Furthermore, we also show two new RNA recognition themes derived from the representative data set. © 2009 Wiley Periodicals, Inc. J Comput Chem 2009