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Biomedical subjects

G Nickless

Publications and source records attributed to G Nickless.

At least 19 recordsLinked to original sources
PubMed2004

Introduction to the DAPPLE Air Pollution Project.

The Dispersion of Air Pollution and its Penetration into the Local Environment (DAPPLE) project brings together a multidisciplinary research group that is undertaking field measurements, wind tunnel modelling and computer simulations in order to provide better understanding of the physical processes affecting street and neighbourhood-scale flow of air, traffic and people, and their corresponding interactions with the dispersion of pollutants at street canyon intersections. The street canyon intersection is of interest as it provides the basic case study to demonstrate most of the factors that will apply in a wide range of urban situations. The aims of this paper are to introduce the background of the DAPPLE project, the study design and methodology for data collection, some preliminary results from the first field campaign in central London (28 April-24 May 2003) and the future for this work. Updated information and contact details are available on the web site at http://www.dapple.org.uk.

Air Pollution↗
PubMed2001

Use of capillary gas chromatography with negative ion-chemical ionization mass spectrometry for the determination of perfluorocarbon tracers in the atmosphere.

A sensitive and selective technique for the quantitative measurement of atmospheric perfluorocarbon trace species at the sub part per quadrillion (10(-15)) levels is presented. The method utilizes advances in adsorbent enrichment techniques coupled with benchtop capillary gas chromatography and negative ion-chemical ionization mass spectrometry. The development and enhancement of sampling technology for tracer experiments is described, and the results from background measurements and a preliminary field experiment are presented. The overall precision of the analytical method with respect to the preferred tracer for these atmospheric transport studies, perfluoromethylcyclohexane, was +/-1.7%. The background concentrations of perfluorodimethylcyclobutane, perfluoromethylcyclopentane, and perfluoromethylcyclohexane at a remote coastal location (Mace Head, Ireland, 53 degrees N, 10 degrees W) were found to be 2.5 (+/-0.4), 6.8 (+/-1.0), and 5.2 fL L(-1) (+/-1.3), respectively. Background concentrations within an urban conurbation (Bristol, U.K.) were slightly greater at 3.0 (+/-1.5), 8.1 (+/-1.8), and 6.3 fL L(-1) (+/-1.1), respectively.

Air Pollutants, Occupational↗
PubMed1988

Chemometric studies of the effect of toxic metals on plants: the use of response surface methodology to investigate the influence of Tl, Cd and Ag on the growth of cabbage seedlings.

The growth of cabbage seedlings at five concentrations of Cd, Tl and Ag was monitored by measuring their wet weights, root and shoot lengths after four week's growth in a controlled environment. Toxicity curves were constructed using a three factor central composite experimental design. The interaction and competition between any two metals were studied by displaying response surfaces. Ag was observed to be the most toxic, while Tl and Cd, although toxic, exhibited fairly similar effects. Analysis of variance was used to test for the significance of each of the computed parameters.

Journal Article↗
PubMed1979

Rapid determination of DDT and related compounds in soils via carbon skeleton gas chromatography-mass spectrometry.

The levels of DDT and related compounds in soil samples from an apple orchard have been determined. Extraction of residues was achieved by cyclic steam extraction and by conventional solvent extraction methods allowing comparison of the two methods. Determination of the organochlorine residues present in the extracts was performed by gas-liquid chromatography-electron-capture detection and by carbon skeleton gas chromatograph-mass spectrometry. Excellent agreement between the two determination techniques was achieved. Prior to application of p,p'-DDT, a value of approximately 0.4 ppm was obtained for Delta DDT in the soil. The major component of this total was DDE. After spraying the apple trees with technical grade, p,p'-DDT, Delta DDT for the soil rose to 0.6 ppm. This increase was due to translocation of p,p'-DDT from the trees.

DDT↗
PubMed1978

Heavy metal complexation in polluted molluscs. III. Periwinkles (Littorina littorea), cockles (Cardium edule) and scallops (Chlamys opercularis).

The accumulation of cadmium, zinc and copper by environmentally contaminated periwinkles, cockles and scallops has been studied by gel permeation chromatography of water-soluble extracts of the shellfish. Three distinct low mol. wt. (less than 3000) zinc complexes were separated from periwinkle extracts. Copper and cadmium were present as a single low mol. wt. species which is apparently responsible for the elevated copper levels in Littorina littorea.

Animals↗
PubMed1977

Heavy metal complexation in polluted molluscs II. Oysters (Ostrea edulis and Crassostrea gigas).

Cadmium, zinc and copper, accumulated from polluted habitats by the oysters Ostrea edulis and Crassostrea gagas, were studied. Three distinct low molecular weight (less than 3000 daltons) zinc complexes were separated from highly contaminated C. gigas, one of which may be a complex with the amino acid taurine. Only one of these zinc complexes was present in less contaminated specimens of O. edulis. On gel permeation chromatography of oyster extracts, copper was eluted together with amino acids (principally taurine) and the betaine homarine. No evidence of metallothionein type proteins was found.

Amino Acids↗
PubMed1977

Heavy metal complexation in polluted molluscs. I. Limpets (Patella vulgata and Patella intermedia).

The accumulation of cadmium, zinc and copper by the marine gastropod molluscs Patella vulgata and Patella intermedia has been studied by gel permeation chromatography of water-soluble extracts of environmentally contaminated shellfish. A major proportion of the water-soluble cadmium and copper in these molluscs is associated with a protein of molecular weight 10 800 daltons. Evidence is presented supporting the similarity of this protein with mammalian metallothionein. This protein contained only a small proportion of the zinc found in the samples.

Amino Acids↗
PubMed1976

Extractants for organochlorine insecticides and polychlorinated biphenyls from water.

A reversed liquid-liquid partition system prepared from Chromosorb W, n-undecane and Carbowax 4000 monostearate was shown to be suitable for extracting organochlorine insecticides and polychlorinated biphenyls (PCBs) from water (with the exception of Aroclor 1260). The performances of the partition system, Amberlite XAD-4, porous polyurethane foam and the solvent extraction technique when applied to the analysis of four environmental water samples were comparable (except for Aroclor 1260).

Adsorption↗