The effect of γ irradiation on the structure of pectin

The effect of γ irradiation on the content of anhydrouronic acid (AUA), degree of esterification (DE), MW and MW-distribution, in addition to the ability to form sugar-acid-gel was investigated. At dose of 2 kGy, a slight increase in the AUA content was observed, obviously DE was decreased. A dramatic decrease in the MW as calculated viscosimetrically or from the HPGPC-elution profile was found.     

Syndecan-1 and Free Indoxyl Sulfate Levels Are Associated with miR-126 in Chronic Kidney Disease

Chronic kidney disease (CKD) is a major cause of death worldwide and is associated with a high risk for cardiovascular and all-cause mortality. In CKD, endothelial dysfunction occurs and uremic toxins accumulate in the blood. miR-126 is a regulator of endothelial dysfunction and its blood level is decreased in CKD patients. In order to obtain a better understanding of the physiopathology of the disease, we correlated the levels of miR-126 with several markers of endothelial dysfunction, as well as the representative uremic toxins, in a large cohort of CKD patients at all stages of the disease. Using a univariate analysis, we found a correlation between eGFR and most markers of endothelial dysfunction markers evaluated in this study. An association of miR-126 with all the evaluated uremic toxins was also found, while uremic toxins were not associated with the internal control, specifically cel-miR-39. The correlation between the expression of endothelial dysfunction biomarker Syndecan-1, free indoxyl sulfate, and total p-cresyl glucuronide on one side, and miR-126 on the other side was confirmed using multivariate analysis. As CKD is associated with reduced endothelial glycocalyx (eGC), our results justify further evaluation of the role of correlated parameters in the pathophysiology of CKD.     

Investigation of the Soret effect in binary,ternary and quaternary hydrocarbon mixtures: New expressions for thermodiffusion factors in quaternary mixtures

Thermodiffusion or the Soret effect in binary, ternary and quaternary hydrocarbon mixtures is studied. Using the linear non-equilibrium thermodynamic (LNET) approach, expressions are derived for the estimation of the thermodiffusion coefficients or factors in quaternary mixtures using different approaches. New series of experimental data for binary, ternary and quaternary mixtures are used to evaluate the performance of the Firoozabadi, Kempers (Haase) and our two developed expressions based on the LNET approach. Results show that the model expressions are generally more effective for binary mixtures. In binary mixtures, the Firoozabadi model is preferred, whereas in ternary and quaternary mixtures, our developed expressions based on the LNET and the LNET–Kempers combined approach are superior. Overall, we may conclude that the LNET approach, extended by the authors to ternary and quaternary mixtures, is a reliable model for less-complex systems, such as the linear hydrocarbon mixtures. The LNET approach is also flexible in that provided the required modifications are made, it may be applicable to more complex systems, such as associating mixtures, as well. It is also argued that a thermodiffusion model should be independent of the mass transfer frame of reference, as thermodiffusion coefficients are calculated at the steady state condition, where all fluxes are zero.     

Numerical and experimental study of the electrofusion welding process of polyethylene pipes

The electrofusion welding process is widely used to join polyethylene components in gas distribution networks. This article provides experimental and 3D‐finite element tools capable of reproducing the major phenomena that occur during an electrofusion process. A specific version of the 3D‐ finite element model simulation software Forge® has been developed to take into account the fitting parameters such as polyethylene thermal properties (i.e., melting and crystallization kinetics, phase transition, and thermal contact resistance) and the electrical and geometrical settings (i.e., welding input parameters). From a numerical point of view, a well refined highly anisotropic mesh adaptation is applied to well capture the contact condition between the heat source and the polyethylene. The computed results (temperature, melted, and cold areas) were compared with experimental data and gave very good agreement in terms of temperature and liquid phase fraction distribution. POLYM. ENG. SCI., 55:123–131, 2015. © 2014 Society of Plastics Engineers     

Electrochemical behavior of AZ91D magnesium alloy in phosphate medium—part I. Effect of pH

The influence of pH on the corrosion behavior of Mg-based AZ91D alloy was investigated in a constant composition phosphate medium using various electrochemical techniques, complemented with surface analysis data. The studied solutions were 0.1 M H₃PO₄, NaH₂PO₄, Na₂HPO₄ and Na₃PO₄ having pH values of 1.8, 4.5, 9.1 and 11.8, respectively. Spontaneous passivation was substantiated from monitoring the continuous positive shift of the open circuit corrosion potential with both immersion time and solution pH. The impedance data indicated more improvement in the insulating properties of the corrosion products formed on the alloy surface with increase in pH. The electrolyte pH plays a determinant influence on surface film properties, as films formed in phosphate solutions with higher pH values are thicker, thus affording better protection for the alloy than those formed in acidic solutions. Good agreement was observed between the results obtained from electrochemical techniques and those from EDX and XRD examinations. The alloy is more susceptible to corrosion in acidic phosphate solutions than in the alkaline ones. Crystalline magnesium (Mg), magnesium hydride (MgH₂) and magnesium oxide (MgO) were found to be the main constituents of the surface film after holding for 2 h in the acidic phosphate medium.     

Enhancement of corrosion resistance of a biomedical grade 316LVM stainless steel by potentiodynamic cyclic polarization

The paper discusses the results on the use of a simple cyclic linear potentiodynamic polarization technique as a method of improving corrosion properties of passive oxide films formed on a biomedical-grade 316LVM stainless steel surface in phosphate buffer. The results demonstrate that the modification of 316LVM surface by cyclic potentiodynamic polarization between the potential of hydrogen and oxygen evolution results in the formation of a passive film that offers significantly increased corrosion resistance (both pitting and general) when compared to the naturally grown passive film. The effect of number of cycles and anodic potential limit on the resulting corrosion properties is discussed. The capacitance analysis demonstrates that the major difference between the electrochemically formed and naturally grown passive film is in the type of semiconductivity in the potential region where pitting on the unmodified surface occurs. The XPS analysis shows that this is due to the presence of Cr(VI)-species in the electrochemically formed passive film, which contribute to the increased density of metal vacancies, and thus to the increased pitting corrosion resistance of the passive film.     

The effects of electrolyte concentration in the emulsion polymerization of styrene

Using concentrations below that required to coagulate the latex, the effects of the addition of potassium chloride on the emulsion polymerization of styrene have been investigated. When potassium decanoate (an emulsifier with a high critical micelle concentration (c.m.c.)) is used the increase in the concentration of micellar emulsifier and the decrease in the area occupied by an emulsifier molecule at the polymer/water interface are significant. When this is taken into account Gardon's equation for latex particle size reproduces the trend of the experimental results at the lower electrolyte concentrations. The agreement can be made quantitative by choosing alternative values for the propagation rate constant of styrene and the rate of radical formation from persulphate. With potassium octadecanoate (which has a low c.m.c.) and with potassium decanoate at the higher electrolyte concentrations these factors cannot account for the results observed.     

Synthetic Unit Hydrograph for Al Fara'a Catchment in the West Bank

Abstract

Synthetic unit hydrographs are frequently used to estimate hydrograph characteristics when observed data are not available. A number of synthetic unit hydrograph approaches are available, but the ones that found widespread use are those based on models of Snyder, Clark, and the U.S. Soil Conservation Services (SCS). The major goal of the study is to develop a synthetic unit hydrograph for Wadi Al Fara'a Catchment, which is un-gauged and considered one of the West Bank's most important catchments. Unfortunately, none of the wadis in the West Bank are gauged and flow records are not available; therefore, it is hoped that this method will be applied successfully for Wadi Al Fara'a catchment and the results can hopefully to be applied to all West Bank catchments, which will facilitate estimation of potential runoff in the whole West Bank.     

Polarimetric image segmentation via maximum-likelihood approximation and efficient multiphase level-sets

This study investigates a level set method for complex polarimetric image segmentation. It consists of minimizing a functional containing an original observation term derived from maximum-likelihood approximation and a complex Wishart/Gaussian image representation and a classical boundary length prior. The minimization is carried out efficiently by a new multiphase method which embeds a simple partition constraint directly in curve evolution to guarantee a partition of the image domain from an arbitrary initial partition. Results are shown on both synthetic and real images. Quantitative performance evaluation and comparisons are also given.