Search results for "Equilibrium"

1975

In the polymerization of isobutene catalyzed by aluminium tribromide and in the polymerization of styrene catalyzed by trifluoromethanesulphonic acid it is supposed that an inactive catalyst monomer complex is formed which is in equilibrium with other active species. The monomer complexation of the catalyst explains the S-shaped conversion curves and the complex kinetics of the polymerization. The value of the equilibrium constant Km (complexation constant) expresses what part of the catalyst may take part in the polymerization process as an active initiating species. For the system isobutene/AlBr3, Km was found to be 0,62 1/mol. In the system styrene/CF3SO3H, the high value of the complexa…

Potentiometric studies on azido complexes of the aquodimethyltin(IV) cation in aqueous solution

1974

Summary Mono and polynuclear azide complexes of the aquodimethyltin(IV) cation have been studied in solution at [ClO 4 − ]=3.00 M , by e.m.f. measurements of [H + ], using the competitive reaction method. Throughout the entire range of data, 2.5≤−log[N 3 − ] free ≤4.9, the results are interpreted by assuming that the complexes {[(CH 3 ) 2 Sn] 3 [N 3 ] 3 } 3+ and [(CH 3 ) 2 Sn(N 3 ) 4 ] 2− predominate; the cumulative equilibrium constants for their formation are log β 33 =12.98±0.03 and log β 14 =2.45±0.02.

1990

The effect of lithium tert-butoxide (t-BuOLi) on rate constants and equilibrium constants of reactions involved in the initial stage of the anionic polymerization of methyl methacrylate (MMA) in tetrahydrofuran, initiated by methyl α-lithioisobutyrate (P) was investigated at 23 ± 3°C. Addition of t-BuOLi decreases the rate constants of initiation and propagation by one order of magnitude; the rate constants of termination by cyclization decrease by two orders of magnitude. This leads to an overall tenfold higher preference of propagation with respect to termination and explains the favourable effect of alkoxide in the polymerization reported earlier. Within experimental error, the equilibri…

Vapor−Liquid Equilibrium of Binary Mixtures of Tetrachloroethylene with 1-Pentanol, 3-Methyl-1-butanol, and 2-Methyl-1-butanol

1999

Isobaric vapor−liquid equilibria have been obtained for the systems tetrachloroethylene + 1-pentanol, tetrachloroethylene + 3-methyl-1-butanol, and tetrachloroethylene + 2-methyl-1-butanol, using a...

Electrochemical determination of the stability of complexes formed by proton-ionizable ligands of 3,5-disubstituted 1H-pyrazole with phenethylamine

1999

The application of two extreme models for diffusion in two-component systems to electrochemically determine equilibrium constants is discussed. The application of cyclic voltammetric, diferential pulse and rotating-disc electrode voltammetric data to elucidate the stoichiometry and formation constant of complex species by applying a generalization of the molar-ratio method is described. Molar-ratio experiments permit the distinction between the limiting diffusive regimes. The values of the equilibrium stability constants for complexation of phenethylamine and phenethylammonium ions by a 26-membered dioxotetraester crown of 3,5-disubstituted 1H-pyrazole as free ligand 1[L] and as dipyrazolat…

Correlation between Cognition and Balance among Middle-Aged and Older Adults Observed through a Tai Chi Intervention program

2020

Background: Age-associated decline in cognition and balance may cause severe ability loss for daily living activities among middle-aged and older adults. The relationship between cognition and balance in this aging population remains to be explored. Objective: The present study Is exploratory in nature and aimed to examine the relationship between balance (both static and dynamic components) and global cognitive function among middle-aged and older adults through Tai Chi (TC) practice as a research avenue. Methods: A short-term (12 weeks) intervention of TC was conducted among middle-aged and older adults in the community setting. Global cognitive function (using the Chinese version of the …

Stability of foreign aid agreement: a general equilibrium experimental analysis

2011

Lower bound limit analysis by bem: Convex optimization problem and incremental approach

2013

Abstract The lower bound limit approach of the classical plasticity theory is rephrased using the Multidomain Symmetric Galerkin Boundary Element Method, under conditions of plane and initial strains, ideal plasticity and associated flow rule. The new formulation couples a multidomain procedure with nonlinear programming techniques and defines the self-equilibrium stress field by an equation involving all the substructures (bem-elements) of the discretized system. The analysis is performed in a canonical form as a convex optimization problem with quadratic constraints, in terms of discrete variables, and implemented using the Karnak.sGbem code coupled with the optimization toolbox by MatLab…

THE PHYSICAL ORIGIN OF PROTEIN DYNAMICAL TRANSITION: A LIQUID-LIQUID TRANSITION IN HYDRATION WATER?

2015

In this thesis I study, by means of neutron scattering, calorimetry, and dielectric spectroscopy, the physical origin of protein dynamical transition (PDT) which is usually observed at ~230 K in protein hydrated powders and is deemed necessary for protein function. Measurements reported in this thesis have been performed on hydrated powders of Myoglobin. The combined use of different experimental techniques gives a coherent description of the PDT and reveals a connection with a liquid-liquid crossover occurring in the protein hydration water at about the same temperature. In order to deepen our understanding of this connection and to obtain a direct experimental evidence of the existence of…

The role of emotions and literature in public deliberation: the figure of Martha C. Nussbaum ‘s perceptive equilibrium

2015

This article argues that literature can play a key role in the processes of ethical deliberation; therefore it can be regarded as an extremely useful tool to justify public decision-making. In order to support this thesis I examine Nussbaum’s proposal of perceptive equilibrium as a method to conduct the public deliberation processes which integrates the emotions in its structure. Finally, I analyse one of the possible applications of the proposed method: introducing narrative texts, both historical and fictional, in the curricula as a method for ethical deliberation.