Dissolution potential of alkali halides in N,N-dimethyl formamide

Phase potential, diffusion potential, observed and true dissolution potentials of alkali halides in N,N-dimethyl formamide have been determined. True dissolution potentials are found to be positive in DMF. The sign and magnitude of these potentials have been explained on the basis of difference between the ionic mobilities of cations and anions.     

Microencapsulation of Tender Coconut Water by Spray Drying: Effect of <Emphasis Type="Italic">Moringa oleifera</Emphasis> Gum,Maltodextrin Concentrations,and Inlet Temperature on Powder Qualities

The present study was aimed to evaluate the different proportions of carrier materials: Moringa oleifera gum (MG), maltodextrin (MD), and inlet temperature on the powder characteristics of encapsulated tender coconut water (TCW) by spray drying. The characterization of microparticle was studied as encapsulation efficiency, antioxidant activity, total phenolic content, moisture content, water activity, solubility, particle morphology, and encapsulation yield. The investigation was conducted using an experimental design of 2² mixes with five replicates at the center point. The encapsulation efficiency was affected by all tested variables and reached significantly (p < 0.05) higher value (94.86%) when higher MG concentration, and lower MD concentration, and inlet temperature were applied. The DPPH (53.66%) and ABTS radical scavenging activity (54.92%) was observed to be higher at the highest MG concentration (1.5%). The obtained powder retained a higher amount of phenol content (21.82 mg GAE/g) at increasing MG concentration, with decreasing MD concentration, and inlet temperature. X-ray diffraction (XRD) analysis revealed that TCW powder encapsulated with 1.5% MG exhibited higher crystalline nature as compared to microparticle encapsulated with 0.5 and 1% MG. The optimum wall material composition and inlet temperature were determined as follows: MD 30%, MG 1.5%, and 120 °C inlet temperature. Hence, our results suggest that the application of this technology could increase the use of TCW in various industrial applications and imply MG as a potent candidate for microencapsulation of food materials.     

Adhesion inhibition of F1C-fimbriated Escherichia coli and Pseudomonas aeruginosa PAK and PAO by multivalent carbohydrate ligands

In order to evaluate their inhibition of bacterial adhesion, the carbohydrate sequences GalNAcbeta1-->4Gal and GalNAcbeta1-->4Galbeta1-->4Glc were synthesized. The disaccharide was conjugated to dendrons based on the 3,5-di-(2-aminoethoxy)-benzoic acid branching unit to yield di- and tetravalent versions of these compounds. A divalent compound was also prepared that had significantly longer spacer arms. Relevant monovalent compounds were prepared for comparison. Their anti-adhesion properties against F1C-fimbriated uropathogenic Escherichia coli were evaluated in an ELISA-type assay by using a recombinant strain and also by using Pseudomonas aeruginosa strains PAO and PAK. Adhesion inhibition was observed in all cases, and multivalency effects of up to one order of magnitude were observed. The combination of spacer and multivalency effects led to a 38-fold increase in the potency of a divalent inhibitor with long spacer arms towards the PAO strain when compared with the free carbohydrate.     

Speciation and Electronic Structure of La<Subscript>1−x</Subscript>Sr<Subscript>x</Subscript>CoO<Subscript>3−δ</Subscript> During Oxygen Electrolysis

Cobalt-containing perovskite oxides are promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, a lack of fundamental understanding of oxide surfaces impedes rational catalyst design for improved activity and stability. We couple electrochemical studies of epitaxial La_1?xSr_xCoO_3?δ films with in situ and operando ambient pressure X-ray photoelectron spectroscopy to investigate the surface stoichiometry, adsorbates, and electronic structure. In situ investigations spanning electrode compositions in a humid environment indicate that hydroxyl and carbonate affinity increase with Sr content, leading to an increase in binding energy of metal core levels and the valence band edge from the formation of a surface dipole. The maximum in hydroxylation at 40% Sr is commensurate with the highest OER activity, where activity scales with greater hole carrier concentration and mobility. Operando measurements of the 20% Sr-doped oxide in alkaline electrolyte indicate that the surface stoichiometry remains constant during OER, supporting the idea that the oxide electrocatalyst is stable and behaves as a metal, with the voltage drop confined to the electrolyte. Furthermore, hydroxyl and carbonate species are present on the electrode surface even under oxidizing conditions, and may impact the availability of active sites or the binding strength of adsorbed intermediates via adsorbate–adsorbate interactions. For covalent oxides with facile charge transfer kinetics, the accumulation of hydroxyl species with oxidative potentials suggests the rate of reaction could be limited by proton transfer kinetics. This operando insight will help guide modeling of self-consistent oxide electrocatalysts, and highlights the potential importance of carbonates in oxygen electrocatalysis.     

Experimental and numerical investigation of cutting forces in micro-milling of polycarbonate glass

Abstract

Polycarbonates have found important applications in various types of industries including optical, automotive, aerospace, biomedical, and defense manufacturing industries. Conventional mechanical machining has the capability to create complex multi-scale parts and components for various materials including polymeric materials. This study investigates the cutting forces generated during the machining of polycarbonate glass using the micro-milling process. The goal of this research is to machine high quality micro-channels in polycarbonates for microfluidic applications. Both experimental investigation and numerical simulations using the Finite Element Method (FEM) have been carried out to assess the cutting forces generated in three directions during machining of polycarbonate. The effectiveness of tool coating on the reduction of cutting forces has been investigated. It was found that with the careful combination of depth of cut and feed rate, the ductile mode machining of polycarbonate can be achieved, which produces lower cutting forces, that could result in improved surface finish and low tool wear. Both lower and higher of depths of cut were found to generate higher cutting forces due to dragging action and higher tool-workpiece contact area respectively. The Finite Element Method (FEM) was found to be effective in simulating the cutting forces with acceptable range of errors, and thus, could be used to predict cutting forces at the parametric combinations beyond the capacity of the machine or without carrying out further expensive experimentation, for which the chances of tool failure are higher.     

Using a geotextile with flocculated filter backwash water and its impact on aluminium concentrations

The use of geotextiles (i.e. geotextile tubes) in wastewater treatment applications is ever increasing. This paper examines the potential of using a geotextile to improve upon the treatment of aluminium present in a filter backwash water that is generated from a water treatment plant in Halifax, Canada. A field investigation to ascertain the distribution of aluminium in the filter backwash water treatment process is provided and compared to regulatory guidelines at the environmental compliance point. It is shown that aluminium is undergoing incomplete treatment at various times throughout the year. To examine a potential corrective action, the results of bench scale studies are presented in which cationic additives (i.e. CaO, MgO, and Fe₃O₄) are combined with a polymer to remove aluminium from solution and flocculate particulate matter from the filter backwash water. A geotextile is utilized to retain particulate matter generated from this process. It is shown that the combined use of the cationic additive with polymer can successfully reduce aluminium concentrations in the filter backwash water and that filtration via a geotextile can retain the aluminium particulate in the filter backwash water to levels close to regulatory requirements. Further optimization with the flocculation process is recommended prior to pilot testing.     

Optimized and Dynamic Selection of Cluster Head Using Energy Efficient Routing Protocol in WSN

Wireless Personal Communications - Wireless Sensor Networks plays an outstanding role in providing dynamic cluster head (CH) selection. However, the selection of CH is a major challenge due to...