Membrane distillation operated at high seawater concentration factors: Role of the membrane on CaCO3 scaling in presence of humic acid

This study aims at investigating the kinetics of calcium carbonate precipitation (scaling), that occurs in the form of vaterite, when treating seawater by direct contact membrane distillation (DCMD) operated at high concentration factors (from 4 to 6). Induction time measurements carried out by dynamic light scattering (DLS) allowed to identify the shifting between homogeneous and heterogeneous nucleation mechanisms as a function of supersaturation. CaCO₃ interfacial energy, evaluated for concentrated seawater solutions as 45 mJ/m², increased by 7% as a consequence of the inhibition effect of humic acid, and it was reduced to 32 mJ/m² in correspondence of heterogeneous nucleation occurring on microporous polypropylene membranes. Gibbs free energy barrier to the formation of critical nuclei was predicted with good accuracy as a function of physico-chemical properties of the membrane (porosity: 0.70, contact angle: 115 ± 2°).     

The viscosity of the methanol-<Emphasis Type="Italic">n</Emphasis>-decane system in the region of low <Emphasis Type="Italic">n</Emphasis>-decane concentrations

The kinematic viscosity and density of the methanol-n-decane system were measured at various temperatures at low n-decane concentrations (over the miscibility range). The theory of free volume with taking into account molecular association was used to calculate the dynamic viscosity of this system at 298.15 K. The results substantiated the presence of an anomaly in this system (positive Δlnη values).     

Water soluble poly(ethylene oxide) functionalized norbornene polymers

The synthesis of three different poly(ethylene oxide) macromonomers with a norbornene and oxanorbornene end group is presented. The macromonomers were polymerized to comb‐polymers by ring‐opening metathesis polymerization (ROMP) using Grubbs' Catalyst G3 to produce water soluble polymers with polydispersities between 1.04 and 1.30 and molecular weights between 14,000 and 50,000 g/mol. Characterization by static and dynamic light scattering reveals that the comb‐polymers with norbornene backbone are molecularly disperse in aqueous solution, while the oxanorbornene‐backbone polymers form small water‐soluble aggregates. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2640–2648, 2008     

Determination of the binding constants of modafinil enantiomers with sulfated β‐cyclodextrin chiral selector by capillary electrophoresis using three different linear plotting methods

Binding constants for the enantiomers of modafinil with the negatively charged chiral selector sulfated‐β‐CD (S‐β‐CD) using CE technique is presented. The calculations of the binding constants employing three different linearization plots (double reciprocal, X‐reciprocal and Y‐reciprocal) were performed from the electrophoretic mobility values of modafinil enantiomers at different concentrations of S‐β‐CD in the BGE. The highest inclusion affinity of the modafinil enantiomers were observed for the S‐enantiomer–S‐β‐CD complex, in agreement with the computational calculations performed previously. Binding constants for each enantiomer–S‐β‐CD complex at different temperatures, as well as thermodynamic parameters for binding, were calculated. Host–guest binding constants using the double reciprocal fit showed better linearity (r²>0.99) at all temperatures studied (15–30°C) and compared with the other two fit methods. The linear van't Hoff (15–30°C) plot obtained indicated that the thermodynamic parameters of complexation were temperature dependent for the enantiomers.     

Ueber die Untersuchung von Drogen und den daraus hergestellten K?rpern

Ohne Zusammenfassung     

Kinetics of hydrolysis of procaine in aqueous and micellar media

The kinetics of alkaline hydrolysis of procaine under the pseudo–first‐order condition ([OH^?] ? [procaine]) has been carried out. N,N‐Diethylaminoethanol and p‐aminobenzoate anion were obtained as the hydrolysis product. The rate of hydrolysis was found to be linearly dependent upon [NaOH]. The addition of cationic cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DDTAB) and tetradecyltrimethylammonium bromide, and anionic sodium dodecyl sulfate (SDS) micelles inhibited the rate of hydrolysis. The maximum inhibitive effect on the reaction rate was observed for SDS micelles, whereas among the cationic surfactants, CTAB inhibited most. The variation in the rate of hydrolysis of procaine in the micellar media is attributed to the orientation of a reactive molecule to the surfactant and the binding constant of procaine with micelles. The rate of hydrolysis of procaine is negligible in DDTAB micelles. The observed results in the presence of cationic micelles were treated on the basis of the pseudophase ion exchange model. The results obtained in the presence of anionic micelles were treated by the pseudophase model, and the various kinetic parameters were determined. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 1–9, 2013     

A decrease in the superluminescence threshold of composites of an organic dye with nanoparticles

It is established that admixture of Ag, Al, Cu, Ni, Zn, and Fe ₃ O ₄ nanoparticles to a rhodamine 6G solution in ethanol with a concentration of 10⁻² mol/L that fills a cell with a thickness of 600 μm results in a decrease in the superluminescence thresholds by no less than 50 folds. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 77–82, September, 2008.     

Evaluation of vanillic acid as inhibitor of carbonic anhydrase isozyme III by using a modified Hummel–Dreyer method: approach for drug discovery

α‐3 carbonic anhydrase isozyme (CAIII) is the most abundant protein in adipocytes and considered insensitive to sulfonamide inhibitors. It was reported recently that the knock‐down of CAIII is attributed with controlling lipogenesis. Thus inhibition of this target may lead to the discovery of new therapies against obesity and insulin resistance. Vanillic acid as a small molecule with coordinating groups and has a potential to bind zinc atoms in CA binding sites. Inhibition of CAIII by vanillic acid was evaluated by Hummel–Dreyer chromatography because it provides free interaction between ligand and macromolecule and introduces solution for faulty results obtained by current colorimetric assays. HPLC system of vanillic acid produces vacancy (negative) peak representing the amount of attached vanillic acid with CAIII. It was found that vanillic acid is able to bind with CAIII through two equilibria, one at equimolar ratio and another at 2:1 (vanillic acid–CAIII) ratio. The affinity constant of equimolar binding between CAIII and vanillic acid was found to be 14,400 m ^?1. It was found that vanillic acid binding with CAIII is much stronger than phenol and acetazolamide (positive controls). Copyright © 2013 John Wiley & Sons, Ltd.