The kinetics of the decarboxylation of n-butylmalonic acid in alkanols and amines

Rate constants and activation parameters are reported for the decarboxylation of n-butylmalonic acid in four normal alkanols (hexanol? 1, octanol? 1, decanol? 1, and dodecanol? 1) and in five amines (aniline, N-methylaniline, N-ethylaniline, N-n-propylaniline, and N-n-butylaniline). Both ΔH? and ΔS? of the reaction in both homologous series decrease regularly with increasing length of the hydrocarbon chain of solvent. If we compare data for the reaction in alkanol–amine pairs containing the same total number of carbon atoms in the molecule, we find that the ΔH? values are identical, but that the value of ΔS? is 0.8 eu/mole higher for the reaction in the amines as compared with the alcohol. The rate constant, at all temperatures, is 1.5 times as large in the amine as it is in the corresponding alcohol. Empirical equations are deduced relating the parameters ΔH? ΔS? ΔG? and k of the reaction to the parameters n and T, where n is the total number of carbon atoms in the solvent molecule and T is the absolute temperature. The results reported herein are compared with previously reported data for malonic acid.     

The effect of silane incorporation on a metal adhesive interface: A study by electron energy loss spectroscopy

A silane-based adhesive formulation, used in the aerospace industry, was studied using sub-nanometre spatially resolved energy loss spectroscopy, as a function of the concentration of silane used in the adhesive. The changes in the relative oxygen concentration and the occupancy of p-type states in the oxygen density of states reveal the existence of a composite layer between the aluminium and the epoxy resin. This composite layer is prevalent in the 1% (w/w) organosilane sample, whilst it is smaller or absent for the 0.5% and 2% (w/w) silane concentration. These observations correlate well with the observed macroscopic durabilities observed when these adhesives are used for the structural adhesive bonding of aluminium aerospace alloys.     

Left Ventricular Geometry,Tissue Composition,and Residual Stress in High Fat Diet Dahl-Salt Sensitive Rats

Background

Hypertension drives myocardial remodeling, leading to changes in structure, composition and mechanical behavior, including residual stress, which are linked to heart disease progression in a gender-specific manner. Emerging therapies are also targeting constituent-specific pathological features. All previous studies, however, have characterized remodeling in the intact tissue, rather than isolated tissue constituents, and did not include sex as a biological variable.

Objective

In this study we first identified the contribution of collagen fiber network and myocytes to the myocardial residual stress/strain in Dahl-Salt sensitive rats fed with high fat diet. Then, we quantified the effect of hypertension on the remodeling of the left ventricle (LV), as well as the existence of sex-specific remodeling features.

Methods

We performed mechanical tests (opening angle, ring-test) and histological analysis on isolated constituents and intact tissue of the LV. Based on the measurements from the tests, we performed a stress analysis to evaluate the residual stress distribution. Statistical analysis was performed to identify the effects of constituent isolation, elevated blood pressure, and sex of the animal on the experimental measurements and modeling results.

Results

Hypertension leads to reduced residual stress/strain in the intact tissue, isolated collagen fibers, and isolated myocytes in male and female rats. Collagen remains the largest contributor to myocardial residual stress in both normotensive and hypertensive animals. We identified sex-differences in both hypertensive and normotensive animals.

Conclusions

We observed both constituent- and sex-specific remodeling features in the LV of an animal model of hypertension.

     

The polarizability of a pair of hydrogen atoms at long range

The coefficients of R^?6 and R^?9 in the long-range expansion of the parallel and perpendicular components of the polarizability of a pair of hydrogen atoms at a separation R have been calculated. The results are A⁽⁶⁾₆ = 2558.59. A⁽⁶⁾_⊥ = 1268.25, A⁽⁸⁾₆ = 90639.5 and A⁽⁸⁾_⊥ = 22010.3 au. The values of A⁽⁶⁾₆ and A⁽⁶⁾₆ and A⁽⁶⁾_| are somewhat larger than previous theoretical estimates and much larger than the classical values of 729 and 182.25 au. The terms in R^?8 arise from distortion associated with the dispersion forces and from the field of the quadrupole moment induced by the field-gradient at each atom.     

Metallation studies of organofunctional trisiloxanes

Summary The organofunctional trisiloxanes Me₃SiOSiMe(R)OSiMe₃ [R=(CH₂)₂PPh₂, (CH₂)₃C₅H₄N, (CH₂)₃CN, (CH₂)₂Ph, (CH₂)₂SPh, CH=CH₂ and CH₂CH=CH₂] have been reacted with metal halide and-carbonyl moieties in order to determine the coordination preferences of materials being used as models for metallated longchain linear functionalised polysiloxanes. The products [Me₃SiOSiMe(R)OSiMe₃]₃ML_n [R=(CH₂)₂PPh₂, ML_n=RhCl],cis-[Me₃SiOSiMe(R)OSiMe₃]₂ML_n [R=(CH₂)₂PPh₂ or (CH₂)₃C₅H₄N, ML_n=Mo(CO)₄],trans-[Me₃SiOSiMe(R)OSiMe₃]₂ML_n[R=(CH₂)₂PPh₂, ML_n=NiCl₂, PdCl₂, PtCl₂ and [Rh(CO)Cl] and [Me₃SiOSiMe(R)OSiMe₃]ML_n [R=(CH₂)₂PPh₂, ML_n=Mo(CO)₃(2,2-bipyridine); R=(CH₂)₂Ph, ML_n=Mo(CO)₃; R=(CH₂)₃C₅H₄N, (CH₂)₃CN, or (CH₂)₂SPh, ML_n=Rh(CO)₂Cl; R=CH=CH₂ or CH₂CH=CH₂, ML_n=Fe(CO)₄] have been isolated and characterised spectroscopically in the course of these studies.     

Recoil polarimetry in meson photoproduction at MAMI

The nucleon excitation spectrum remains poorly known, with the masses, widths, EM couplings and even existence of many states not well established. A program of experiments using meson photoproduction off the nucleon is being carried out to improve this situation. A new large acceptance recoil polarimeter has been developed by the Edinburgh group for use in such reactions with the Crystal Ball at MAMI. This work summarizes the procedure used to measure recoil polarization with the new device and presents some preliminary results for the double polarization observable C_x in the reaction γp→pπ~0, compared to the current partial wave analysis.