Analysis of pathogenic bacteria using exogenous volatile organic compound metabolites and optical sensor detection

A novel, low-cost and simple method for the detection of pathogenic bacteria is proposed. The approach is based on the generation of an exogenous volatile organic compound (VOC) produced by the addition of an enzyme substrate to the bacterial sample. The generated VOC is then trapped in agarose gel allowing colour development to take place; visual detection is then possible by both the naked eye and by colorimetric analysis. Agarose gel has been evaluated as both a suitable VOC trapping matrix and host for the colour-generating reagents. This proof of concept method allowed for the discrimination between β-glucosidase and β-alanyl aminopeptidase producing bacteria. Enterococcus faecium and Klebsiella pneumoniae are both β-glucosidase producers and generated a yellow colour within agarose gels upon enzymatic hydrolysis of 2-nitrophenyl-β-D-glucoside. Pseudomonas aeruginosa is a known β-alanyl aminopeptidase producer and was shown to hydrolyse the trifluoroacetic acid (TFA) salt of 3-amino-N-phenylpropanamide resulting in the development of an orange colour within agarose gels spiked with the sodium salt of 1,2-naphthoquinone-4-sulfonic acid. 3-Amino-N-phenylpropanamide (as its TFA salt) and 2-nitrophenyl-β-D-glucoside concentrations of 20 μg mL−1 (or 72 μmol L−1) and 100 μg mL−1 (or 332 μmol L−1), respectively were the minimum quantities required for colour production following 18 h of incubation. The use of 3-amino-N-phenylpropanamide, TFA salt indicated that synthesised enzyme substrates can be tailor-made to liberate exogenous VOCs for colour generation

Some clinical impressions of halothane

No Abstract

The non-tidal surface current system of the northern and middle areas of the North Sea, as ascertained by experiments with drift-bottles

The present thesis consists of three papers recently published by His Majesty's Stationery Office in the series of "Scientific Investigations" issued under the authority of the Fishery board for Scotland. The inclusive title and the subtitles of these papers appear on the respective title-pages and are given in the foregoing contents table. The relationship of the inclusive title to that under which this thesis is presented is discussed in the concluding chapter of the thesis.Appended to the above publications are two shorter papers, one of which has also been published, the other having been communicated on behalf of the writer to the body named on the title-page. All five papers are original in form and in subtance, the work having been performed at the Marine Laboratory of the fishery Board for Scotland in Aberdeen, under the supervision of the Board's Scientific Superintendent, Alexander Bowman, D.Sc., F.R.S.E., on whose initiative the experiments dealt with in the main body of the thesis were carried out.The experiments in question consisted in the liberation of large numbers of specially-prepared, floating bottles, from numerous widespread points in the Northern and Middle North Sea, the southern reaches of the Norwegian Sea and the Faroe-Shetland Channel. Primarily, they were designed to yield information of consequence to marine biological research in connection with the Northern North Sea fisheries and, already, the results so far obtained have been of service in this direction. It may be added that, along with the liberation of drift-bottles, physical observations of the temperature and salinity of the sea water were taken at practically every 'liberation-station' and this material is presently forming the subject of a separate study to which the drift-bottle interpretations are proving a valuable asset.From the biological standpoint the original aim of the drift- bottle work was to obtain an understanding of matters relative to the passive transport of fish eggs, larval forms and indeed, all plankton. Physically, therefore, its immediate objective was the elucidation of surface water movements in the above areas, or, more specifically, the measurement of the quantity generally referred to as the surface drift*, in its chief characteristics of direction and velocity. A definition of the term 'surface drift' is given in the concluding chapter to the thesis.From the biological standpoint the original aim of the drift- bottle work was to obtain an understanding of matters relative to the passive transport of fish eggs, larval forms and indeed, all plankton. Physically, therefore, its immediate objective was the elucidation of surface water movements in the above areas, or, more specifically, the measurement of the quantity generally referred to as the surface drift*, in its chief characteristics of direction and velocity. A definition of the term 'surface drift' is given in the concluding chapter to the thesis.As submitted, the main thesis consists of two parts. Part I is a statistical treatment, on fairly broad lines, of the data pertaining to the five years, 1910 to 1914 inclusive and is in the nature of an introductory to Part II.The latter comprises two sections, of which the first is a detailed analysis, on a cartographical basis, of the results of the 1910 liberations and the second, a similarly exhaustive study,of the 1911 data. In oruer to complete ?art II on the lines originally laid down in accordance with the exigencies of departmental economy, three more sections remain to be published at intervals, as circumstances allow. For the purposes of this thesis, however, the three n papers now presented form a complete whole in so far as the analyses of the materials for the two years above-mentioned have resulted in new knowledge which has been taken to a definite climax and much of which is remarkably corroboreted within these pages, This last circumstance also bespeaks the wider applicability of these analytical results than as representative merely of the two years in question.Consequent upon the necessity of publishing this work in sections, each memoir, as it appeared, was concluded with a summary chapter based on the results obtained from each analysis, in a final chanter to the present thesis these results and especially their significance are discussed with somewhat greater latitude, introducing certain ideas conceived in the course of this investigation and pointing the way to further research

Chlorpromazine hydrochloride in anaesthesia

No Abstract