The chemical interaction of oxygen and olefins

All the material incorporated in this thesis has a common theme, in that it is concerned with the elucidation f the chemical mechanism by which non -conjugated olefins eact with molecular oxygen. The constituent investigations re of two general types. On the one hand, since the xidation mechanism is of the chain type, it is possible to 'rig changes on the mode of chain initiation and chain ermination, in such a way as to provide a set of closely elated chemical systems, which by exhibiting significant ifferences in kinetic behaviour build up a well - substantiated picture of the general oxidation mechanism. his work was carried out almost exclusively in the pecially favourable case of ethyl linoleate, and is escribed in Sections 3 -7.In the second place, the elementary chemical processes hich go to make up this mechanism may depend markedly on he detailed chemical structure of the olefin concerned. ections 10 -12 form part of a systematic investigation of his aspect of autoxidation. One class of olefins - the olyisoprenes - has been studied in rather greater detail: ections 8 and 9 describe complementary investigations of he oxidation kinetics and of the nature of the primary oxidation product as indicated by organo- analytical methods.No attempt will be made here to relate in detail the various sections one to another, or to present the general context of published work into Which they may be fitted: it is hoped that this requirement is adequately met by Section 2. Marginal references have been inserted in this latter section, to facilitate reference to the appropriate parts f the thesis.Section 13 consists of a short communication which ummarises the results of an investigation into the 'nteraction of molecular oxygen and alcohols. It has been 'ncluded in this thesis since it emphasises the respects in rhich another major class of substrate conforms to and iverges from the oxidative behaviour of the olefins

Correlation of Certain Characters in Ears of Moody County White Dent Corn

The idea has been prevalent that the most cylindrical ears of corn have the largest percentage of corn on them, and it has been the purpose of this study to determine the correlation coefficient between the degree of taper and the percentage of shelled corn on ears of Moody County White Dent

Effects of Reflection and Refraction of Ultrasonic Waves on the Angle Beam Inspection of Anisotropic Composite Material

Nondestructive testing of composite materials by ultrasonic techniques has several specific features resulting from strong material anisotropy and inhomogeneity. This requires reexamination of old testing methodologies and development of new ones. The latest developments in this direction were recently reviewed by Henneke and Duke [1] and by Bar-Cohen [2]

Greener pastures 6 - Managing soil acidity in dairy pastures

During 1999-2009, soil testing for pH (in CaCl2) was used to determine lime application for 48 paddocks at the Vasse Research Centre at Busselton, in the south-west of Western Australia (WA). Paddocks had been grazed intensively by dairy cows and their young stock over a period of 10 years, as part of the Vasse Milk Farmlets and Greener Pastures farming system projects. Pasture consisted of annual ryegrasses with some subterranean clover. Soils in the 48 paddocks were 1-2 m sand to sandy loam over massive clay, known locally as Abba sand. For many soils in the region, including Abba sands, the topography is flat and the soils are waterlogged from June to early September in the typical May to November growing season. No major liming program had been undertaken in the 48 paddocks before April 1999, and soil testing in 1999 indicated soil pH for the top 10 cm of soil was 4.0-5.0 in all paddocks. Soil acidification was therefore identified as a major problem, and a liming program was undertaken to rectify the problem, starting in 1999.https://researchlibrary.agric.wa.gov.au/bulletins/1127/thumbnail.jp

Temporal and spatial variations in the abundance and population structure of the spined loach (Cobitis taenia), a scarce fish species: implications for condition assessment and conservation

Effective conservation of protected species requires accurate estimates of the status of their populations. In the UK, this led to the production of a series of sampling protocols to establish the status of designated species against predetermined conservation objectives: a process known as 'condition assessment'. Condition assessments involve comparisons of various parameters, invariably including abundance and/or population structure, of the target species against criteria that are judged to be indicative of viable populations.This study investigated temporal and spatial variations in the abundance and population structure of spined loach (Cobitis taenia), a scarce species indigenous to Europe and central Asia. Specifically, the study compared the density, number of age classes and percentage contribution of the 0+ year age class of spined loach between day and night, months, years and locations.There were marked diel, seasonal, annual and spatial variations in the density, number of age classes and percentage contribution of 0+ year spined loach. Such phenomena are important because monitoring programmes conducted at inappropriate times of day or year, or with insufficient frequency or geographical coverage, could lead to inaccurate assessments of the condition of protected populations and, consequently, to inadequate conservation measures. Notwithstanding, there were few impacts on the condition assessments of the spined loach populations because at least one of the parameters invariably failed to satisfy the population condition assessment criteria.A prerequisite for successful conservation is an effective monitoring programme. It is therefore essential that surveys to assess the condition of populations of protected species are designed with due consideration of their diel behaviour, breeding season, life span and habitat use. It is recommended that the monitoring protocol and condition assessment criteria for spined loach are amended, and that surveys are conducted by trawling, in late summer, at least every 3-4years

Genetic microheterogeneity and phenotypic variation of Helicobacter pylori arginase in clinical isolates

BACKGROUND: Clinical isolates of the gastric pathogen Helicobacter pylori display a high level of genetic macro- and microheterogeneity, featuring a panmictic, rather than clonal structure. The ability of H. pylori to survive the stomach acid is due, in part, to the arginase-urease enzyme system. Arginase (RocF) hydrolyzes L-arginine to L-ornithine and urea, and urease hydrolyzes urea to carbon dioxide and ammonium, which can neutralize acid. RESULTS: The degree of variation in arginase was explored at the DNA sequence, enzyme activity and protein expression levels. To this end, arginase activity was measured from 73 minimally-passaged clinical isolates and six laboratory-adapted strains of H. pylori. The rocF gene from 21 of the strains was cloned into genetically stable E. coli and the enzyme activities measured. Arginase activity was found to substantially vary (>100-fold) in both different H. pylori strains and in the E. coli model. Western blot analysis revealed a positive correlation between activity and amount of protein expressed in most H. pylori strains. Several H. pylori strains featured altered arginase activity upon in vitro passage. Pairwise alignments of the 21 rocF genes plus strain J99 revealed extensive microheterogeneity in the promoter region and 3' end of the rocF coding region. Amino acid S232, which was I232 in the arginase-negative clinical strain A2, was critical for arginase activity. CONCLUSION: These studies demonstrated that H. pylori arginase exhibits extensive genotypic and phenotypic variation which may be used to understand mechanisms of microheterogeneity in H. pylori