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.     

A simple expression for the buffer index of a weak polyprotic acid

A simple expression for the buffer index of a solution containing a weak polyprotic acid is derived and presented.     

Z-dependence of the intensity of |Δn|=2 pionic X-rays

The intensity per stopped π^?of|Δn|=2 pionic X-rays are observed to have larger variations with atomic number Z than do the |Δn|=1. The 6–4 intensity has a well-defined maximum at Z=34 with a FWHM of ΔZ ～10.     

Static moments of the first excited states of 32, 34S and 204, 206Pb

The reorientation effect in Coulomb excitation has been used to measure the following static quadrupole moments: $\text{Q}{}_2\text{+ (}{}^{32}\text{S}\text{) = ?0.066 ± 0.017}\text{b}\text{, Q}{}_2\text{+ (}{}^{34}\text{S}\text{) = 0.026 ± 0.023}\text{b}\text{, Q}{}_2\text{+ (}{}^{204}\text{Pb}\text{) = 0.19 ± 0.14}\text{b}$. Interference effects from higher excited states have been included in the analysis, with the signs of the E2 matrix elements taken from an anharmonic model. The value obtained for $\text{Q}{}_2\text{+ (}{}^{32}\text{S}\text{)}$ is in disagreement with two previous measurements. We attribute the discrepancy to the smaller internucleon separation distances involved in the previous experiments, which can cause deviations from Coulomb excitation cross sections. The other quadrupole moments have not been measured previously. The B (E2: 0⁺ → 2⁺) measured were: $\text{0.0305 ± 0.0016 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{32}\text{S}\text{), 0.025 ± 0.004 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{34}\text{S}\text{),}\text{and}\text{0.166 ± 0.009 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{204}\text{Pb}\text{)}$. From the angular distribution of the de-excitation γ-rays of the Pb nuclei following recoil into vacuum, we have determined the following $\text{g-}\text{factors}\text{: ¦g}{}_2\text{+ (}{}^{204}\text{Pb}\text{)¦ < 0.08}$ (two standard deviations), $\text{¦g}{}_2\text{+ (}{}^{206}\text{Pb}\text{)¦ = 0.07}{}^{\mathrm{+\; 0.07}}{}_{\mathrm{?\; 0.03}}$. Our value of $\text{g}{}_2\text{+ (}{}^{206}\text{Pb}\text{)}$ is in agreement with a previous measurement.     

Evidence for a kaon-bound state K(-)pp produced in K(-) absorption reactions at rest

We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e(+)e(-) collider DAPhiNE. Almost monochromatic K(-)'s produced through the decay of phi(1020) mesons are used to observe K(-) absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K(-)pp through its two-body decay into a Lambda hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115(+6)(-5)(stat)(+3)(-4)(syst) MeV and 67(+14)(-11)(stat)(+2)(-3)(syst) MeV, respectively.     

Measurement of the resonant d(mu)t molecular formation rate in solid HD

Measurements of muon-catalyzed dt fusion ( d(mu)t-->4He + n + mu(-)) in solid HD have been performed. The theory describing the energy dependent resonant molecular formation rate for the reaction (mu)t + HD-->[(d(mu)t)pee](*) is compared to experimental results in a pure solid HD target. Constraints on the rates are inferred through the use of a Monte Carlo model developed specifically for the experiment. From the time-of-flight analysis of fusion events in 16 and 37 microg x cm(-2) targets, an average formation rate consistent with 0.897+/-(0.046)(stat)+/-(0.166)(syst) times the theoretical prediction was obtained.     

Field-induced motion of ferrofluids through immiscible viscous media: Testbed for restorative treatment of retinal detachment

Biocompatible, hydrophobic ferrofluids comprised of magnetite nanoparticles dispersed in polydimethylsiloxane show promise as materials for the treatment of retinal detachment. This paper focuses on the motion of hydrophobic ferrofluid droplets traveling through viscous aqueous media, whereby the movement is induced by gradients in external fields generated by small permanent magnets. A numerical method was utilized to predict the force on a spherical droplet, and then the calculated force was used to estimate the time required for the droplet to reach the permanent magnet. The calculated forces and travel times were verified experimentally.