Assessment of the polluting effects of the Iponri-Alaka Canal,Lagos State,Nigeria

ABSTRACT

The polluting effects of Iponri-Alaka Canal in Surulere area of Lagos State on the environment have been studied using six sampling points. The study aimed at assessing the effects of exposure to pollutants on humans and other life forms. The quality of air, wastewater and sediments was assessed between March and August 2017. The concentrations of SO₂ and H₂S were measured using MSA Altair 5X. Temperature, pH and DO were measured in-situ using Thermometer, pH meter and Winkler method, respectively. TSS, TDS, TS, TA, TH, BOD, chloride Cl^?, PO₄^3-, SO₄^2- and NO₃^? were determined using appropriate standard methods in the laboratory. EC and some heavy metals (Cr, Pb, Mn, Cd and Ni) concentrations were determined using conductivity meter and Atomic Absorption Spectroscopy, respectively. The results showed that pH, TS, DO and TH were well within the WHO and FEPA maximum limits. EC, SO₄^2- and TDS were observed to be higher than guideline values only at one sampling point. The TSS, BOD, TA, NO₃^? and PO₄^3- were higher than WHO and FEPA guideline limits at all sampling points. Cr was seen to be within, while Pb and Mn were higher than WHO and FEPA guideline values. Cd was higher than guideline values only at two sampling points. Ni was below detection concentration at all the sampling points.

The concentration of SO₂ was seen to be higher than WHO and NESREA guideline values at two sampling points, while H₂S concentration was higher than WHO limit at all the six sampling points.     

pePC-SAFT: Modeling of polyelectrolyte systems: 1. Vapor–liquid equilibria

A molecular thermodynamic model for polyelectrolyte systems—called pePC-SAFT—is proposed. The effect of charged monomers within the polyelectrolyte chain is explicitly taken into account in the reference term by replacing the hard-chain contribution of the PC-SAFT model by a charged-hard-chain contribution. Moreover, counterion condensation is accounted for to determine the effective number of charges along the polyion as well as of free counterions. The electrostatic contribution of the free counterions is described by a Debye–Hückel term.     

The mean association number: Ultraviolet spectroscopic study of PbCl2−H2O−C2H5OH

The concept of mean asociation number (MAN) has been proposed to describe the association state of an electrolyte. Both the mean spherical approximation (MSA) and the generalized mean spherical approximation (GMSA) are used to calculate the MAN. The theoretical results obtained are compared to the experiment results from an ultraviolet spectroscopic study of PbCl₂–H₂O–C₂H₅OH solutions and also to the predictions of the Bjerrum theory as given by Friedman.     

Adsorptive micro-extraction techniques--novel analytical tools for trace levels of polar solutes in aqueous media

A novel enrichment technique, adsorptive μ-extraction (AμE), is proposed for trace analysis of polar solutes in aqueous media. The preparation, stability tests and development of the analytical devices using two geometrical configurations, i.e. bar adsorptive μ-extraction (BAμE) and multi-spheres adsorptive μ-extraction (MSAμE) is fully discussed. From the several sorbent materials tested, activated carbons and polystyrene divinylbenzene phases demonstrated the best stability, robustness and to be the most suitable for analytical purposes. The application of both BAμE and MSAμE devices proved remarkable performance for the determination of trace levels of polar solutes and metabolites (e.g. pesticides, disinfection by-products, drugs of abuse and pharmaceuticals) in water matrices and biological fluids. By comparing AμE techniques with stir bar sorptive extraction based on polydimethylsiloxane phase, great effectiveness is attained overcoming the limitations of the latter enrichment approach regarding the more polar solutes. Furthermore, convenient sensitivity and selectivity is reached through AμE techniques, since the great advantage of this new analytical technology is the possibility to choose the most suitable sorbent to each particular type of application. The enrichment techniques proposed are cost-effective, easy to prepare and work-up, demonstrating robustness and to be a remarkable analytical tool for trace analysis of priority solutes in areas of recognized importance such as environment, forensic and other related life sciences.     

桂皮酰胺类化合物分子形状与抗惊活性定量构效关系的研究

采用分子形状分析法研究了26个桂皮酰胺类化合物的结构与抗惊活性的定量关系。相关方程表明抗惊活性与化合物的脂水分配系数(log P)及重叠的表面积(S_0)呈抛物线关系,与酰胺基团的 C—O 键长和 C—N 键长的乘积(代表酰胺基团的面积)呈线性关系。     

巯基丁二酸修饰的碲化镉量子点溶液显现不同客体表面潜指纹

利用具有宽且连续的荧光激发光谱和窄且对称的荧光发射光谱的水溶性巯基丁二酸修饰的碲化镉量子点溶液,成功显现了多种客体表面的潜指纹,且1～3s即可得到良好效果.该材料成功显现了水浸客体和粘连客体表面的潜指纹,而且在显现连续按捺产生的微弱指纹时展现出了优良的灵敏度.同龙胆紫、罗丹明6G和巯基乙酸修饰的CdTe量子点溶液相比,该溶液拥有更快的显现速度和更好的显现效果.     

Phosphopeptide fragmentation and analysis by mass spectrometry

Reversible phosphorylation is a key event in many biological processes and is therefore a much studied phenomenon. The mass spectrometric (MS) analysis of phosphorylation is challenged by the substoichiometric levels of phosphorylation and the lability of the phosphate group in collision‐induced dissociation (CID). Here, we review the fragmentation behaviour of phosphorylated peptides in MS and discuss several MS approaches that have been developed to improve and facilitate the analysis of phosphorylated peptides. CID of phosphopeptides typically results in spectra dominated by a neutral loss of the phosphate group. Several proposed mechanisms for this neutral loss and several factors affecting the extent at which this occurs are discussed. Approaches are described to interpret such neutral loss‐dominated spectra to identify the phosphopeptide and localize the phosphorylation site. Methods using additional activation, such as MS³ and multistage activation (MSA), have been designed to generate more sequence‐informative fragments from the ion produced by the neutral loss. The characteristics and benefits of these methods are reviewed together with approaches using phosphopeptide derivatization or specific MS scan modes. Additionally, electron‐driven dissociation methods by electron capture dissociation (ECD) or electron transfer dissociation (ETD) and their application in phosphopeptide analysis are evaluated. Finally, these techniques are put into perspective for their use in large‐scale phosphoproteomics studies. Copyright © 2009 John Wiley & Sons, Ltd.     

From restricted towards realistic models of salt solutions: Corrected Debye–Hückel theory and Monte Carlo simulations

The properties of bulk salt solutions over wide concentration ranges are explored by a combination of simple physical theory and Monte Carlo (MC) simulations. The corrected Debye–Hückel (CDH) theory which incorporates ion size effects in a linear response approximation is extended to yield free energy and other thermodynamic properties by integration of the chemical potential over concentration. Charging integration which is usually used to obtain an electrostatic contribution of total free energy of electrolytes is avoided in this new direct approach. MC simulations are performed with a modified Widom particle insertion method, which also provides directly the ionic activity coefficients. The validity of the CDH theory is tested by comparison with the MC simulation data for 1:1, 2:1, 2:2 and 3:1 restricted primitive model (RPM) electrolytes over a wide concentration range and at various ion sizes. Mean ionic activity and osmotic coefficients calculated by the CDH theory in RPM approximation of electrolyte are fitted to experimental data by adjusting only a mean ionic diameter. Good fits up to 1 molal (m) concentration are obtained for a large number of salt solutions. MC simulations data for unrestricted primitive model (UPM) of 1:1 and 2:1 electrolytes are also fitted to the experimental data by varying the cation radius while keeping the anion radius fixed at a crystallographic value. The success of this approach is found to be salt specific. For example good fits up to 2 and 3.5 m concentrations were obtained for LiCl and LiBr, respectively. However in the case of less dissociated salts such as NaCl and KI the experimental data could only be fitted up to one molal concentration. Possibility of extending the applicability range of the CDH theory to concentrations >2 m is explored by including a concentration dependent dielectric constant as measured in experiments. Mean ionic activity coefficients for a number of salts could successfully be fitted up to 3 m concentration by adjusting only a mean ionic diameter. Difficulties encountered in simultaneously fitting the mean ionic activity and osmotic coefficients at salt concentrations >2 m are discussed.     

Molybdate Sulfuric Acid/NaNO2: A Novel Heterogeneous System for the N‐Nitrosation of Secondary Amines under Mild Conditions

Wet molybdate sulfuric acid (= dioxo[bis(sulfato‐κO)]molybdenum; MSA), a new solid acid, can be used in combination with sodium nitrite (NaNO₂) to transform a variety of secondary amines to the corresponding N‐nitroso compounds under mild, heterogeneous conditions (Table). The process has several advantages: the reagents are inexpensive and non‐hazardous, the reaction is clean, fast, and high‐yielding, and MSA can be readily removed by filtration and re‐used (after treatment with HCl) without loss of activity. Further, only N‐nitrosation was observed, but no C‐ or O‐nitrosation.     

Affine invariant feature extraction algorithm based on multiscale autoconvolution combining with texture structure analysis

Affine invariant feature extraction has been one of the key issues for object recognition, especially for the images captured under the variable environments. Considering that multiscale autoconvolution feature (MSA), which has the prominent comprehensive performance, is very sensitive to illumination change, a novel algorithm of extracting affine invariant feature is proposed based on the MSA transform combining with texture structure analysis. Firstly, a new MSA feature is extracted from texture structure map of the image which is computed based on local binary pattern theory. And then the original image based MSA and the texture map based MSA are combined to a new feature using generalized canonical correlation analysis, called TFMSA. This new feature represents much more image information than the traditional one and is performed in various object recognition tasks. The experimental results indicate that the new TFMSA not only conquers the defect of the traditional MSA, but also has good adaptability for a certain range of viewing angles, partial occlusion, uniform and non-uniform illumination changes. The recognition accuracy of the new feature is superior to MSA and other improved methods.