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Solubility Properties (solubility + property)

Distribution by Scientific Domains
Polymers and Materials Science42%

Selected Abstracts

Thermal Sensitivity of tert -Butyloxycarbonylmethyl-Modified Polyquats in Condensed Phase and Solubility Properties of Copolymers with N -Isopropylacrylamide

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2010
Nina Gonsior
Abstract The synthesis of the easily decomposable ionic monomer 2- tert -butoxy- N -[2-(methacryloyl-oxy)ethyl]- N,N -dimethyl-2-oxoethanammonium chloride (3) via thermally induced syn-elimination of a tert -butyl ester group was realized simply by mixing N,N -dimethylaminoethyl methacrylate (1) and tert -butyl chloroacetate (2) at ambient temperature without solvent. The obtained salt was polymerized via free radical polymerization. The decomposition and foaming via iso -butene formation takes place by heating up to about 160,°C. IR, DSC, TGA, and GC/MS measurements were performed to follow this pyrolysis reaction. Furthermore, the copolymerization of 3 with N -isopropylacrylamid (NiPAAm, 5) was carried out with different monomer ratios. Molar mass distributions were measured using an asymmetrical flow field-flow fractionation (aFFFF) system. The obtained copolymers 6,10 exhibit lower critical solution temperature (LCST) behaviour in water with cloud points at different temperatures depending on the monomer ratio. [source]

Solubility properties of human tooth mineral and pathogenesis of dental caries

ORAL DISEASES, Issue 5 2004
T Aoba
Dental research over the last century has advanced our understanding of the etiology and pathogenesis of caries lesions. Increasing knowledge of the dynamic demineralization/remineralization processes has led to the current consensus that bacteria-mediated tooth destruction can be arrested or even to some degree reversed by adopting fluoride and other preventive measures without using restorative materials. Our experimental approach provided new insight into the stoichiometries and solubility properties of human enamel and dentin mineral. The determination of the solubility product constant on the basis of the stoichiometric model (Ca)5·x(Mg)q(Na)u(HPO4)v(CO3)w(PO4)3·y(OH,F)1·z, verifies the difference in their solubility properties, supporting the phase transformation between tooth mineral and calcium phosphates in a wide range of fluid compositions as found in the oral environment. Further refinement of the stoichiometry and solubility parameters is essential to assess quantitatively the driving force for de- and remineralization of enamel and dentin in the oral fluid environment. Prediction of the effects of a combination of inhibitors and accelerator(s) on remineralization kinetics is also required. In order to develop devices efficient for optimizing remineralization in the lesion body, it is a critical question how, and to what extent, fluoride can compensate for the activity of any inhibitors in the mineralizing media. [source]

New sets of solubility parameters of linear and crosslinked aromatic polyamides

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
Stefano Fiori
Abstract As generally accepted, also in the case of polyamides linear and crosslinked polymeric materials are believed to be characterized by the same solution properties and, consequently, by the same solubility parameters. However, despite their great practical importance, a thorough study aimed to determine the best solvent media able to dissolve linear aromatic polyamides has not been performed yet or, at least, has not been published. In this study, we report on our study on the solubility parameters of linear and crosslinked aromatic polyamides. We demonstrate that the assumption of considering these two classes as having the same solubility properties can lead to dramatically erroneous results. Two new different sets for linear and crosslinked aromatic polyamides are proposed. Namely, linear poly(p -phenylene terephthalamide) is characterized by ,p, ,d, and ,H equal to 8.6, 18.4, and 11.3, respectively; by contrast, the corresponding values of the crosslinked aromatic polyamides taken into consideration are: 11.5, 16.8, and 10.2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Influence of [Ba + Ca]/[Ti + Zr] Ratio on the Interfacial Property of (Ba,Ca)(Ti,Zr)O3 (BCTZ) Powders in an Aqueous Medium

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2003
Jaeho Lee
We report findings on the electrokinetic and solubility behaviors of (Ba,Ca)(Ti,Zr)O3 (BCTZ) powders having three different [Ba + Ca]/[Ti + Zr] ratios: 0.995, 1.000, and 1.005. Electrokinetic and solubility properties of BCTZ powders in aqueous media are phenomenologically similar to BaTiO3. Ba and Ca ions, occupying primarily A-sites on the perovskite lattice, dissolve during acid titration, which results in surface depletion of A-site cations in the surface region of BCTZ particles. The electrokinetics of colloidal BCTZ powders reflects changes in the surface chemistry that occur as a result of dissolution and adsorption/reprecipitation of surface ions. An increase in [Ba + Ca]/[Ti + Zr] ratio results in an increase in the dynamic mobility at all pH values, an increase in the titration hysteresis, and an increase in the isoelectric pH. Each of these effects can be attributed to Ba and Ca in the near-surface region of BCTZ. [source]

Solubility properties of human tooth mineral and pathogenesis of dental caries

ORAL DISEASES, Issue 5 2004
T Aoba
Dental research over the last century has advanced our understanding of the etiology and pathogenesis of caries lesions. Increasing knowledge of the dynamic demineralization/remineralization processes has led to the current consensus that bacteria-mediated tooth destruction can be arrested or even to some degree reversed by adopting fluoride and other preventive measures without using restorative materials. Our experimental approach provided new insight into the stoichiometries and solubility properties of human enamel and dentin mineral. The determination of the solubility product constant on the basis of the stoichiometric model (Ca)5·x(Mg)q(Na)u(HPO4)v(CO3)w(PO4)3·y(OH,F)1·z, verifies the difference in their solubility properties, supporting the phase transformation between tooth mineral and calcium phosphates in a wide range of fluid compositions as found in the oral environment. Further refinement of the stoichiometry and solubility parameters is essential to assess quantitatively the driving force for de- and remineralization of enamel and dentin in the oral fluid environment. Prediction of the effects of a combination of inhibitors and accelerator(s) on remineralization kinetics is also required. In order to develop devices efficient for optimizing remineralization in the lesion body, it is a critical question how, and to what extent, fluoride can compensate for the activity of any inhibitors in the mineralizing media. [source]

The I-antigens of Ichthyophthirius multifiliis are GPI-Anchored Proteins

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 3 2001
THEODORE G. CLARK
ABSTRACT. The parasitic ciliate Ichthyophthirius multifiliis has abundant surface membrane proteins (i-antigens) that when clustered, trigger rapid, premature exit from the host. Similar antigens are present in free-living ciliates and are GPI-anchored in both Paramecium and Tetrahymena. Although transmembrane signalling through GPI-anchored proteins has been well-documented in metazoan cells, comparable phenomena have yet to be described in protists. Since premature exit of Ichthyophthirius is likely to involve a transmembrane signalling event, we sought to determine whether i-antigens are GPI-anchored in these cells as well. Based on their solubility properties in Triton X-114, the i-antigens of Ichthyophthirius are amphiphilic in nature and partition with the detergent phase. Nevertheless, following treatment of detergent lysates with phospholipase C, the same proteins become hydrophilic. Concomitantly, they are recognized by antibodies against a cross-reacting determinant exposed on virtually all GPI-anchored proteins following cleavage with phospholipase C. Finally, when expressed in recombinant form in Tetrahymena thermophila, full-length i-antigens are restricted to the membrane, while those lacking hydrophobic C-termini are secreted from the cell. Taken together, these observations argue strongly that the i-antigens of Ichthyophthirius multifiliis are, in fact, GPI-anchored proteins. [source]

Design and Synthesis of a Focused Library of Novel Aryl- and Heteroaryl-Ketopiperazides

ARCHIV DER PHARMAZIE, Issue 12 2004
Matthias Gerlach
Abstract 1-Phenyl-4-piperazinyl-carbonyl-substituted nitrogen-containing heterocycles were discovered at Zentaris as a new class of potent, synthetic, small molecule tubulin inhibitors with strong antiproliferative activity. The lead structure of this class, D-24203, proved to be a potent inhibitor of in vivo tumor growth in different xenograft models including mammary and renal cancers. As part of our efforts in the lead optimization process to expand structural diversity as well as to optimize bioavailability parameters such as solubility and metabolic stability for these compounds, we produced and evaluated a focused library containing 320 compounds. Five new heterocyclic compound classes with comparable activity properties in the cytotoxicity and tubulin polymerization assay could be identi fied. In silico calculated bioavailability parameters for selected library members provides new compound classes with improved solubility properties. Library design, development of adequate solution phase methodology, and synthesis will be presented, as well as results of lead optimization. [source]