Search results for "kinetics"

ChemInform Abstract: Hydrate Networks under Mechanical Stress - A Case Study for Co3(PO4)2·8H2O.

2016

The mechanochemically (ball milling) induced loss of bound H2O in Co3(PO4)2·8H2O is investigated together with an associated phase transition and its kinetics by powder synchrotron XRD and quantitative IR spectroscopy.

No Label Required: Protein Binding at Membrane Interfaces Visualized through Colloid Phase Transitions

2004

Modelling of phase transitions and reaction at CO adsorption on oxygen precovered Pd(111)

2006

Abstract Using the interaction parameters up to the third neighbors and activated form of O and CO diffusion and their reaction, the model has been proposed for Monte-Carlo simulations describing the catalytic O + CO → CO2 reaction and occurring phase transitions on Pd(1 1 1) surface. Upon adsorption of CO the pre-adsorbed oxygen transforms from p(2 × 2)O phase into 3 × 3 R 30 O ° and 3 × 3 R 30 O ° → p ( 2 × 1 ) O phases in the limit of room and moderate temperatures, respectively. We demonstrate that the kinetic effects determine both the occurrence of the p(2 × 1)O and disappearance of the 3 × 3 R 30 O ° phases at moderate and low temperatures, respectively. Using reaction rate as a fit …

Dehydration of detomidine hydrochloride monohydrate

2010

The thermodynamic stability of detomidine hydrochloride monohydrate has been evaluated on the basis of phase transition kinetics in solid state. A method free of empirical models was used for the treatment of kinetic data, and compared to several known solid state kinetic data processing methods. Phase transitions were monitored by powder X-ray diffraction (PXRD) and thermal analysis. Full PXRD profiles were used for determining the phase content instead of single reflex intensity measurements, in order to minimize the influence of particle texture. We compared the applicability of isothermal and nonisothermal methods to our investigation of detomidine hydrochlorine monohydrate dehydration.

Modelling phase transition kinetics of chenodeoxycholic acid with the Runge–Kutta method

2009

Abstract The phase transition kinetics of two chenodeoxycholic acid polymorphic modifications— form I (stable at high temperature), form III (stable at low temperature) and the amorphous phase has been examined under various conditions of temperature and relative humidity. Form III conversion to form I was examined at high temperature conditions and was found to be non-spontaneous, requiring seed crystals for initiation. The formation kinetic model of form I was created incorporating the three-dimensional seed crystal growth, the phase transition rate proportion to the surface area of form I crystals, and the influence of the amorphous phase surface area changes with an empirical stage poin…

Increasing the Templating Effect on a Bulk Insulator Surface: From a Kinetically Trapped to a Thermodynamically More Stable Structure

2016

Molecular self-assembly, governed by the subtle balance between intermolecular and molecule- surface interactions, is generally associated with the thermodynamic ground state, while the competition between kinetics and thermodynamics during its formation is often neglected. Here, we present a simple model system of a benzoic acid derivative on a bulk insulator surface. Combining high-resolution non-contact atomic force microscopy experiments and density functional theory, we characterize the structure and the thermodynamic stability of a set of temperature-dependent molecular phases formed by 2,5-dihydroxybenzoic acid molecules, self- assembled on the insulating calcite (10.4) surface. We d…

Kinetics of dielectric response in SBN-75 ceramics at infra-low frequencies under illumination

2014

A study of the photo-dielectric effect in ferroelectric SBN-75 ceramics of a broad phase transition under light of small intensity is reported. Relations determining kinetics of the infra-low frequency dielectric response under light and after illumination are obtained from experimental measurements revealing the features of the behaviour of relaxation time constants of the dielectric polarisation with temperature.

Time scale of protein aggregation dictated by liquid-liquid demixing

2003

The growing impact of protein aggregation pathologies, together with the current high need for extensive information on protein structures are focusing much interest on the physics underlying the nucleation and growth of protein aggregates and crystals. Sickle Cell Hemoglobin (HbS), a point-mutant form of normal human Hemoglobin (HbA), is the first recognized and best-studied case of pathologically aggregating protein. Here we reanalyze kinetic data on nucleation of deoxy-HbS aggregates by referring them to the (concentration-dependent) temperature Ts characterizing the occurrence of the phase transition of liquid-liquid demixing (LLD) of the solution. In this way, and by appropriate scalin…

Control of cellular phosphatidylinositol 4,5-bisphosphate levels by adhesion signals and Rho GTPases in NIH 3T3 fibroblasts

2000

The involvement of small GTPases of the Rho family in the control of phosphoinositide metabolism by adhesion signals was examined in NIH 3T3 fibroblasts. Abrogation of adhesion signals by detachment of cells from their substratum resulted in a time-dependent decrease in the cellular level of PtdIns(4,5)P2 by approximately 50%. This effect could be mimicked by treatment of adherent cells with Clostridium difficile toxin B and toxin B-1470, which inhibit specific subsets of Rho and Ras GTPases. Detachment of cells that had been pretreated with the clostridial toxins did not cause a further reduction in PtdIns(4,5)P2 levels, suggesting that the target GTPases are integrated into the control of…

Phosphorylation of GAP-43 (growth-associated protein of 43 kDa) by conventional, novel and atypical isotypes of the protein kinase C gene family: dif…

1996

GAP-43 (growth-associated protein of 43 kDa; also known as neuromodulin, P-57, B-50 and F-1) is a neuronal calmodulin binding protein and a major protein kinase C (PKC) substrate in mammalian brain. Here we describe the phosphorylation by and the site specificity of different PKC isotypes. The conventional PKC beta 1 and the novel PKCs delta and epsilon effectively phosphorylated recombinant GAP-43 in vitro; atypical PKC zeta did not. The K(m) values (between 0.6 and 2.3 microM) were very low, demonstrating a high-affinity interaction between kinase and substrate. All PKC isotypes were shown to phosphorylate serine-41 in GAP-43. When using a 19-amino-acid oligopeptide based on the GAP-43 ph…