7 resultados para asymmetry equation of state of nuclear matter

em Aston University Research Archive


Relevância:

100.00% 100.00%

Publicador:

Resumo:

The equation of state for dense fluids has been derived within the framework of the Sutherland and Katz potential models. The equation quantitatively agrees with experimental data on the isothermal compression of water under extrapolation into the high pressure region. It establishes an explicit relationship between the thermodynamic experimental data and the effective parameters of the molecular potential.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The organic matter in five oil shales (three from the Kimmeridge Clay sequence, one from the Oxford Clay sequence and one from the Julia Creek deposits in Australia) has been isolated by acid demineralisation, separated into kerogens and bitumens by solvent extraction and then characterised in some detail by chromatographic, spectroscopic and degradative techniques. Kerogens cannot be characterised as easily as bitumens because of their insolubility, and hence before any detailed molecular information can be obtained from them they must be degraded into lower molecular weight, more soluble components. Unfortunately, the determination of kerogen structures has all too often involved degradations that were far too harsh and which lead to destruction of much of the structural information. For this reason a number of milder more selective degradative procedures have been tested and used to probe the structure of kerogens. These are: 1. Lithium aluminium hydride reduction. - This procedure is commonly used to remove pyrite from kerogens and it may also increase their solubility by reduction of labile functional groups. Although reduction of the kerogens was confirmed, increases in solubility were correlated with pyrite content and not kerogen reduction. 2. O-methylation in the presence of a phase transfer catalyst. - By the removal of hydrogen bond interactions via O-methylation, it was possible to determine the contribution of such secondary interactions to the insolubility of the kerogens. Problems were encountered with the use of the phase transfer catalyst. 3. Stepwise alkaline potassium permanganate oxidation. - Significant kerogen dissolution was achieved using this procedure but uncontrolled oxidation of initial oxidation products proved to be a problem. A comparison with the peroxytrifluoroaceticacid oxidation of these kerogens was made. 4. Peroxytrifluoroacetic acid oxidation. - This was used because it preferentially degrades aromatic rings whilst leaving any benzylic positions intact. Considerable conversion of the kerogens into soluble products was achieved with this procedure. At all stages of degradation the products were fully characterised where possible using a variety of techniques including elemental analysis, solution state 1H and 13C nuclear magnetic resonance, solid state 13C nuclear magnetic resonance, gel-permeationchromatography, gas chromatography-mass spectroscopy, fourier transform infra-red spectroscopy and some ultra violet-visible spectroscopy.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A version of the thermodynamic perturbation theory based on a scaling transformation of the partition function has been applied to the statistical derivation of the equation of state in a highpressure region. Two modifications of the equations of state have been obtained on the basis of the free energy functional perturbation series. The comparative analysis of the experimental PV T- data on the isothermal compression for the supercritical fluids of inert gases has been carried out. © 2012.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The Nuclear Magnetic Resonance (NMR) spectra of liquids contain a wealth of quantitative information that may be derived, for instance, from chemical shifts and spin-spin couplings. The available information depends on the incoherent rapid molecular motion that causes complicating effects present in the solid state to average to zero. Whereas liquid state NMR spectra show narrow lines, the corresponding NMR spectra from the solid state are normally composed of exceedingly broad resonance lines due to highly restricted molecular motion. It is, therefore, difficult to obtain directly as detailed information from the spectra of solids as from those derived from the liquid state. Studies on a new technique (SINNMR, the sonically induced narrowing of the NMR spectra of solids) to remove line broadening effects in the NMR spectra of the solid state are reported within this thesis. SINNMR involves narrowing the NMR absorptions from solid particles by irradiating them with ultrasound when they are suspended in a support liquid. It is proposed that ultrasound induces incoherent motion of the suspended particles, producing motional characteristics of the particles similar to those of rather large molecules. The first report of apparently successful experiments involving SINNMR[1] emphasised both the irreproducibility of the technique and the uncertainty regarding its true origin. If SINNMR can be made reproducible and the effect definitively attributed to the sonically induced incoherent motional averaging of particles, the technique could offer a simple alternative to the now classical magic-angle spinning (MAS) NMR[2] and the recently reported dynamic angle spinning (DAS)[3] and double rotation (DOR)[4] techniques. Evidence is presented in this thesis to support the proposal that ultrasound may be used to narrow the NMR spectral resonances from solids by inducing incoherent motion of particles suspended in support liquids and, additionally, for some solids, by inducing rotational motion of molecular constituents in the lattices of solids. Successful SINNMR line narrowing using 20 kHz ultrasound is reported for a variety of samples: including trisodium orthophosphate, polytetrafluoroethylene and aluminium alloys. Investigations of SINNMR line narrowing in trisodium phosphate have revealed the relationship between ultrasonic power, particle size and support liquid density for the production of optimum SINNMR conditions. It is also proposed that the incoherent motion of particles induced by 20 kHz ultrasound can originate from interactions between acoustically induced cavitation microjets and particles.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The development of adult-onset diseases such as type II diabetes, obesity and cardiovascular disease is traditionally attributed to adult lifestyle characteristics such as a lack of physical exercise, poor diet and smoking. However, evidence from both human and animal model studies has demonstrated that environmental factors such as an imbalance or reduction in maternal nutrition during gestation can have adverse effects on offspring metabolism and cardiovascular health. The severity and nature of the phenotypic changes induced in offspring is influenced by the period of gestation manipulated. In particular, the mammalian preimplantation embryo in different animal models displays particular sensitivity to environmental factors, either in vivo (maternal diet) or in vitro (embryo culture) that is associated with the onset of cardiovascular dysfunction in adult life. The detailed mechanisms by which environmental conditions can alter postnatal cardiovascular physiology are poorly understood. However, various factors including endothelial function, vascular responsiveness, the renin-angiotensin system, kidney structure and early postnatal growth dynamics have all been recognize as potential contributors. Here, we review the relationship between preimplantation embryo environment and postnatal cardiovascular disease risk, and consider biochemical, molecular, genetic and physiological pathways implicated in this association. © 2009 The Authors Journal compilation © 2009 Anatomical Society of Great Britain and Ireland.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This piece argued that the accepted orthodoxy concerning the requirement that each individual piece of property is individually segregated for a valid trust to exist is unsupported by the case law, and that there is nothing wrong in principle or theory with a trust that exists for unsegregated property.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Degeneration of white matter fibre tracts occurs in several neurodegenerative disorders and results in various histological abnormalities including loss of axons, vacuolation, gliosis, axonal varicosities and spheroids, corpora amylacea, extracellular protein deposits, and glial inclusions (GI). This chapter describes quantitative studies that have been carried out on white matter pathology in a variety of neurodegenerative disease. First, in Alzheimer’s disease (AD), axonal loss quantified in histological sections stained with toluidine blue, occurs in several white matter fibre tracts including the optic nerve, olfactory tract, and corpus callosum. Second, in Creutzfeldt-Jakob disease (CJD), sections of cerebral cortex stained with haematoxylin and eosin (H/E) or immunolabelled with antibodies against the disease form of prion protein (PrPsc), reveal extensive vacuolation, gliosis of white matter, and deposition of PrPsc deposits. Third, GI immunolabelled with antibodies against various pathological proteins including tau, -synuclein, TDP-43, and FUS, have been recorded in white matter of a number of disorders including frontotemporal lobar degeneration (FTLD), progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and neuronal intermediate filament inclusion disease (NIFID). Axonal varicosities have also been observed in NIFID. There are two important questions regarding white matter pathology that need further investigation: (1) what is the relative importance of white and gray matter pathologies in different disorders and (2) do white matter abnormalities precede or are they the consequence of gray matter pathology?