Nonlinear renormalization-group analysis applied to the hydrodynamic light scattering spectrum of4He belowT λ

We calculate the observable critical temperature dependence of the transport coefficients entering the hydrodynamic form of the dynamic structure factor of⁴He belowT . Application of our recently introduced nonlinear renormalization-group analysis yields quantitative agreement with previous light scattering experiments in the hydrodynamic region. This resolves a long-standing problem in the critical dynamics below the superfluid transition of⁴He.Supported in part by the Fonds zur Förderung der wissenschaftlichen Forschung     

Nonasymptotic critical dynamics of the asymmetric-spin model in two-loop order

The crossover behaviour in the dynamics near the Lambda transition of⁴He is analyzed on the basis of the complete renormalization-group flow equations for the asymmetric-spin model (F) in two-loop order. Our results confirm the conclusions and refine the results obtained from an earlier analysis based on the symmetric model (E) and invalidate part of a recent analysis treating model F in an unsystematic approximation. Excellent agreement is found with measurements of second-sound damping over four decades in relative temperature. Closer toT our analysis predicts a further increase of the effective amplitudeR ^eff of the thermal conductivity.Supported in part by the Fonds zur Förderung der wissenschaftlichen Forschung     

Experimental and Computational Study of the Thermal Decomposition of 3‐Methyl‐3‐buten‐1‐ol in m‐Xylene Solution

An experimental study of the thermal decomposition of a β‐hydroxy alkene, 3‐methyl‐3‐buten‐1‐ol, in m‐xylene solution, has been carried out at five different temperatures in the range of 513.15–563.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s^?1) = (25.65 ± 1.52) ? (17,944 ± 814) (kJ·mol^?1)·T^?1. A computational study has been carried out at the M05–2X/6–31+G(d,p) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. There is a good agreement between the experimental and calculated rate constants and activation Gibbs energies. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis, which provides the natural atomic charges and the Wiberg bond indices. Based on the results obtained, the mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state, being a concerted and slightly asynchronous process. The results have been compared with those obtained previously by us (Struct Chem 2013, 24, 1811–1816) for the thermal decomposition of 3‐buten‐1‐ol, in m‐xylene solution. We can conclude that in the compound studied in this work, 3‐methyl‐3‐buten‐1‐ol, the effect of substitution at position 3 by a weakly activating CH₃ group is the stabilization of the transition state formed in the reaction and therefore a small increase in the rate of thermal decomposition.     

Structural and Kinetic Aspects of Blood Plasma Protein Adsorption on the Surface of Hydrophobic Polymers

Abstract

Due to the wide use of polymers in medicine, researchers are required to solve a very important problem–to understand the interaction between materials of nonphysiological origin and the surrounding biological liquids, and tissues, particularly blood.     

The correction-to-scaling exponent in dilute systems

The leading correction-to-scaling exponent ω for the three-dimensional (3D) dilute Ising model is calculated in the framework of the field theoretic renormalization group approach. Both in the minimal subtraction scheme and in the massive field theory (resummed four-loop expansion) excellent agreement with recent Monte Carlo calculations (H. G. Ballesteros et al., Phys. Rev. B 58, 2740 (1998)) is achieved. The expression of ω as a series in a expansion up to O(ɛ²) does not permit a reliable estimate for d=3. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 10, 698–702 (25 May 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Frequency-dependent shear viscosity, sound velocity, and sound attenuation near the critical point in liquids. III. The shear viscosity

We compare theoretical results for the shear viscosity calculated in one-loop order within the field-theoretical method of the renormalization-group theory with experiments. Our expressions describe the nonasymptotic crossover in both temperature and density, and allow us to consider effects of finite gravitation and finite frequency at which the experiments are performed. In doing so we treat the critical exponent x(eta) of the shear viscosity as an independent parameter, keeping the one-loop value of the Kawasaki amplitude fixed. Within our model we also consider the temperature and density dependence of the thermal diffusion including gravitational effects.     

A direct preparation of fluorinated imides

N-Fluorosulfuryltrifluoroacetimide and N-chlorosulfuryltrifluoroacetimide have been prepared in high yield by a one-step reaction of trifluorothiolacetic acid with the corresponding fluoro- and chlorosulfuryl isocyanates. The trifluoroacetimides are easily purified by vacuum sublimation from the crude product mixture.