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Complex Solution (complex + solution)

Distribution by Scientific Domains

Polymers and Materials Science	40%
Chemistry	40%

Selected Abstracts

Dispersing Multi-Component and Unstable Powders in Aqueous Media Using Comb-Type Anionic Polymers§

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2006
Eric Laarz
We have investigated the effect of polymeric dispersants on the rheological properties and consolidation behavior of concentrated cemented carbide (WC,Co) and magnesia (MgO) suspensions. The relatively novel types of comb-type anionic polymers with grafted non-ionic side chains are effective dispersants also in multi-component powder mixtures with a complex solution and surface chemistry and result in more robust suspensions at significantly higher solids loading compared with e.g., a traditional cationic polyelectrolyte. Direct force measurements on comb-type dispersants with different lengths of the grafted ethylene oxide side chains showed that the dispersants adsorb onto a MgO surface and infer a repulsion where the range scales with the length of the poly ethylene oxide side chains. The compressibility and the consolidation behavior of MgO particle networks in response to a centrifugal force field could be related to the estimated thickness of the adsorbed comb-type dispersants. [source]

Oxidative polymerization of N -vinylcarbazole in polymer matrix

POLYMER INTERNATIONAL, Issue 6 2001
Belkis Ustamehmeto
Abstract A new class of soluble conductive poly(N -vinylcarbazole) (PVCz) compounds has been developed by oxidative matrix polymerization of N -vinylcarbazole (NVCz) by Ce(IV) in the presence of poly(ethylene glycol) (PEG). PEG was found to be a more suitable matrix with which to obtain a stable homogenous ternary complex solution when compared with poly(acrylic acid) (PAA) and poly(vinylpyrrolidone) (PVP). The role of PEG, NVCz and Ce(IV) concentration, order of component addition, the structure of the polymer matrix, molecular weight of polymer and the effect of solvent have been investigated. Obtaining soluble PEG,Ce(III),PVCz ternary complexes was shown by cyclic voltammetric measurements, and the initial rate of formation NVCz cation radicals as calculated using UV,visible spectrophotometry. Advantageously with these soluble complexes, conductivities could be measured both in solution and in the solid state. © 2001 Society of Chemical Industry [source]

Use of nitrocellulose films for affinity-directed mass spectrometry for the analysis of antibody/antigen interactions

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2001
Shuqing Sun
Combination of affinity extraction procedures with mass spectrometric analyses is termed affinity-directed mass spectrometry, a technique that has gained broad interest in immunology and is extended here with several improvements from methods used in previous studies. A monoclonal antibody was immobilized on a nitrocellulose (NC) membrane, allowing the corresponding antigen to be selectively captured from a complex solution for analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). This method was also used to rapidly determine the approximate binding region responsible for the antibody/antigen interaction. The tryptic fragments of antigen protein in buffer were applied to the antibody immobilized on NC film and allowed to interact. The NC film was then washed to remove salts and other unbound components, and subjected to analysis by MALDI-TOFMS. Using interferon-,2a and anti-interferon-,2a monoclonal antibody IgG as a model system, we successfully extracted the antigen protein and determined the approximate binding region for the antigen/antibody interaction (i.e., the tryptic fragment responsible). Copyright © 2001 John Wiley & Sons, Ltd. [source]

Simple Bisthiocarbonohydrazones as Sensitive, Selective, Colorimetric, and Switch-On Fluorescent Chemosensors for Fluoride Anions

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2007
Feng Han
Abstract Bisthiocarbonohydrazones are found to be a class of sensitive, selective, ratiometric, and colorimetric chemosensors for anions such as fluoride (F,) or acetate (Ac,). The sensitivities, or the binding constants of the sensors with anions, were found to be strongly dependent on the substituents appended on the ,-conjugation framework, the delocalization bridge CHN, the aromatic moiety, and the hetero atom in the CX group (X=O, S) of the sensors. Single-crystal structures and 1H,NMR titration analysis shows that the CHN moiety is a hydrogen-bond donor, and it is proposed that an additional CH,,,F hydrogen bond is formed for the sensors in the presence F,. A sensor bearing anthracenyl groups is demonstrated as a switch-on fluorescent chemosensor for F, and Ac,. The recognition of F, in acetonitrile (MeCN) by a sensor with nitrophenyl substituents is tolerant to MeOH (MeCN/MeOH=10:1, v/v) and water (MeCN/H2O=30:1, v/v); at these solvent ratios the absorption intensity of the sensor,F, complex solution at maximal absorption wavelength was attenuated to half of the original value in pure MeCN. [source]

Patients' explanations for depression: a factor analytic study

CLINICAL PSYCHOLOGY AND PSYCHOTHERAPY (AN INTERNATIONAL JOURNAL OF THEORY & PRACTICE), Issue 1 2008
Rick Budd
Objectives: Previous questionnaire studies have attempted to explore the factor structure of lay beliefs about the causes of depression. These studies have tended to either fail to sample the full range of possible causal explanations or extract too many factors, thereby producing complex solutions. The main objective of the present study was to obtain a more complete and robust factor structure of lay theories of depression while more adequately sampling from the full range of hypothesized causes of depression. A second objective of the study was to explore the relationship between respondents' explanations for depression and their perceptions of the helpfulness of different treatments received. Method and design: A 77-item questionnaire comprising possible reasons for ,why a person might get depressed' was mailed out to members of a large self-help organization. Also included was a short questionnaire inviting respondents to note treatments received and their perceptions of the helpfulness of these treatments. Data from the 77-item questionnaire were subjected to a principal components analysis. Results: The reasons rated as most important causes of depression related to recent bereavement, imbalance in brain chemistry and having suffered sexual assault/abuse. The data were best described by a two-factor solution, with the first factor clearly representing stress and the second factor depressogenic beliefs, the latter corresponding to a cognitive,behavioural formulation of depression aetiology. The two scales thus derived did not, however, correspond substantially with rated helpfulness for different treatments received. Conclusions: The factor structure obtained was in contrast to more complex models from previous studies, comprising two factors. It is likely to be more robust and meaningful. It accords with previous research on lay theories of depression, which highlight ,stress' as a key cause for depression. Possible limitations in the study are discussed, and it is suggested that using the questionnaire with more recently depressed people might yield clearer findings in relation to perceptions of treatment helpfulness.,Copyright © 2008 John Wiley & Sons, Ltd. [source]