Search results for "Opera"

Static measurements of refractive index increments at 633 nm with a modified refractive index detector

1985

A R 401 Waters Assoc. differential refractometer has been modified to obtain the variation of refractive index increments, dn/dc, of polymer solutions at 633 nm. The introduced modifications were in the sample injection system and in the light source. The performance of the modified refractometer both with aqueous and organic solutions is analyzed. In order to localize a conformational transition in lysozyme, the dependence of dn/dc on temperature for lysozyme solutions in phosphate buffer is studied. Similarly, (dn/dc)k values for the ternary n-alkane/butanone/poly(dimethyl siloxane) systems over the whole composition range of the binary solvent mixtures are evaluated.

Speciation of tin(II) in aqueous solution: thermodynamic and spectroscopic study of simple and mixed hydroxocarboxylate complexes

2013

This contribution reports the results of potentiometric and Mossbauer investigations on the formation, stability, and structure of binary and ternary mono- and binuclear complexes of Sn2+ with three hydroxocarboxylic ligands (namely L = tartrate, malate, and citrate) and chloride at T = 298.15 K in different ionic media and ionic strengths (0.15 and 1.00 mol dm−3 in NaCl(aq) and 1.00 mol dm−3 in NaNO3(aq)). The stability constants of various simple Sn i H j L (2+−) and mixed Sn i H j L k Cl (2+−−) species obtained in the different experimental conditions are reported, and various speciation diagrams of the simple and mixed systems are shown in different conditions. The sequestering ability …

Studies of the ternary systems humic substances – kaolinite – Pu(III) and Pu(IV)

2008

AbstractThe behaviour of plutonium with respect to its migration in the aquifer has been studied under conditions close to nature. Most relevant under these conditions are Pu(III) and Pu(IV) in contact with humic substances (HS) and minerals. As a model for the host rock, kaolinite (KGa-1b) was chosen. The complexation of Pu(III) and Pu(IV) with Aldrich humic acid (AHA) in aqueous solution at ionic strength 0.1 M was investigated by the ultrafiltration method. The sorption of Pu(III) and Am(III) onto kaolinite (K) as a function of pH and metal-ion concentration was studied under aerobic and anaerobic conditions. The pH edge was found at pH∼5.5 independent of the metal-ion concentration and …

ChemInform Abstract: Review: Solution Equilibria of Ternary Complexes Formed from Copper(II), Aliphatic Amines, and Bioligands

2014

This review provides a summary of the coordination chemistry of ligands in the ternary system: copper(II)–aliphatic amine–bioligand, where amine = ethylenediamine – En, diethylenetriamine – Dien, or N, N, N′, N″, N″-pentamethyldiethylenetriamine – Me5dien, and bioligand = selected amino acid, aminohydroxamic acid, or aminophosphonic acid, in aqueous solution. We would like to show the specific interactions of copper(II) in ternary systems in the context of complex equilibria chemistry.

Synergy of Axial and Point Chirality to Construct Helical N -Heterotriangulene-Based Supramolecular Polymers

2018

Calculation of phase diagrams not requiring the derivatives of the Gibbs energy for multinary mixtures

1996

A method for the calculation of phase diagrams (tie lines and binodal, spinodal, critical points and their stability) based exclusively on the Gibbs energy of mixing with no need of its derivatives with respect to the composition variables is extended to multinary mixtures for any number of components. The mathematical description of the (K-1)-dimensional phase diagram of a K-component mixture is presented. The method is demonstrated for a quinternary blend of five polymers exhibiting a closed miscibility gap; all binary, ternary and quaternary subsystems are completely miscible. The phase separation in the quinternary system is caused by very favorable interactions in the ternary subsystem…

IDENTIFICATION OF A CALMODULIN-BINDING SITE WITHIN THE DOMAIN I OF BACILLUS THURINGIENSISCry3Aa TOXIN

2012

Bacillus thuringiensis Cry3Aa toxin is a coleopteran specific toxin highly active against Colorado Potato Beetle (CPB).We have recently shown that Cry3Aa toxin is proteolytically cleaved by CPB midgut membrane associated metalloproteases and that this cleavage is inhibited by ADAM metalloprotease inhibitors. In the present study, we investigated whether the Cry3Aa toxin is a calmodulin (CaM) binding protein, as it is the case of several different ADAM shedding substrates. In pull-down assays using agarose beads conjugated with CaM, we demonstrated that Cry3Aa toxin specifically binds to CaM in a calcium-independent manner. Furthermore, we used gel shift assays and (1)H NMR spectra to demons…

Retention behaviour of paracelsin peptides on reversed-phase silicas with varying n-alkyl chain length and ligand density.

1989

As part of further investigations on the characterization of the ligand-induced conformational stabilization of peptides, two series of n-alkyldimethylsilyl bonded silicas have been prepared. In series A the n-alkyl chain length, n, of the bonded phase was varied between 1 and 20 carbon atoms at a constant ligand density. In series B the ligand density, alpha exp, was gradually changed from 0 to 4.1 mumol/m2 on a C1, C4, C6, C8 and C18 bonded phase. The retention behaviour of four peptides of the paracelsin family were examined under isocratic conditions, using a ternary mobile phase of water-methanol-acetonitrile (22:39:39, v/v/v). Plots of k' versus n showed pronounced maxima between n = …

Lattice fluid model generalized for specific interactions: An application to ternary polymer solutions

2011

Abstract The phase diagram of the Poly- l -Lactic-Acid (PLLA), dioxane and water system was derived by using the lattice fluid model generalized for specific interactions. A qualitative analysis of Hansen solubility parameters together with empirical observations were adopted to reduce the number of adjustable parameters. The as-selected model parameters were derived by fitting a set of cloud point curves; consequently, the complete phase diagram of the system was computed. The use of specific interactions between species gave out a quantitative agreement with a set of experimental data, whereas changing the polymer polydispersity the agreement is only qualitative. In principle, the present…

Quick and reliable routes to phase diagrams for polyethersulfone and polysulfone membrane formation

2000

Phase diagrams were measured and calculated for the ternary membrane forming systems DMF/water/polysulfone and DMF/water/polyethersulfone at different temperatures. Customary experiments yielded cloud point curves, tie lines, and critical compositions. The theoretical computation starts from the Flory-Huggins theory and employs binary interaction parameters g ij that vary with the composition. This information was mainly obtained by means of Headspace-Gas Chromatography (HSGC, yielding the partial pressures of the volatile components); these data were complemented by light scattering and swelling experiments. The calculation of binodals, spinodals, tie lines, and critical points avoids the …