DISPERSION EXPERIMENTS IN CENTRAL LONDON Wood, Curtis R.; Arnold, Samantha J.; Balogun, Ahmed A. ...
Bulletin of the American Meteorological Society,
07/2009, Letnik:
90, Številka:
7
Journal Article
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In the event of a release of toxic gas in the center of London, emergency services personnel would need to determine quickly the extent of the area contaminated. The transport of pollutants by ...turbulent flow within the complex streets and building architecture of London, United Kingdom, is not straightforward, and we might wonder whether it is at all possible to make a scientifically reasoned decision. Here, we describe recent progress from a major U.K. project, Dispersion of Air Pollution and its Penetration into the Local Environment (DAPPLE; information online at www.dapple.org.uk). In DAPPLE, we focus on the movement of airborne pollutants in cities by developing a greater understanding of atmospheric flow and dispersion within urban street networks. In particular, we carried out full-scale dispersion experiments in central London from 2003 through 2008 to address the extent of the dispersion of tracers following their release at street level. These measurements complemented previous studies because 1) our focus was on dispersion within the first kilometer from the source, when most of the material was expected to remain within the street network rather than being mixed into the boundary layer aloft; 2) measurements were made under a wide variety of meteorological conditions; and 3) central London represents a European, rather than North American, city geometry. Interpretation of the results from the full-scale experiments was supported by extensive numerical and wind tunnel modeling, which allowed more detailed analysis under idealized and controlled conditions. In this article, we review the full-scale DAPPLE methodologies and show early results from the analysis of the 2007 field campaign data.
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Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The prospects for exploiting proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) in medical diagnostics are illustrated through a series of case studies. Measurements of acetone ...levels in the breath of 68 healthy people are presented along with a longitudinal study of a single person over a period of 1 month. The median acetone concentration across the population was 484 ppbV with a geometric standard deviation (GSD) of 1.6, whilst the average GSD during the single subject longtitudinal study was 1.5. An additional case study is presented which highlights the potential of PTR-ToF-MS in pharmacokinetic studies, based upon the analysis of online breath samples of a person following the consumption of ethanol. PTR-ToF-MS comes into its own when information across a wide mass range is required, particularly when such information must be gathered in a short time during a breathing cycle. To illustrate this property, multicomponent breath analysis in a small study of cystic fibrosis patients is detailed, which provides tentative evidence that online PTR-ToF-MS analysis of tidal breath can distinguish between active infection and non-infected patients.
The theoretical basis of eVOCs as biomarkers for respiratory disease diagnosis is described, followed by a review of the potential biomarkers that have been proposed as targets from in vitro studies. ...The utility of these targets is then discussed based on comparison with results from clinical breath studies. The current status of breath research is summarised for various diseases, with emphasis placed on quantitative and targeted studies. Potential for bias highlights several important concepts related to standardization, including practices adopted for compound identification, correction for background inspired VOC levels and computation of mixing ratios. The compiled results underline the need for targeted studies across different analytical platforms to understand how sampling and analytical factors impact eVOC quantification. The impact of environmental VOCs as confounders in breath analysis is discussed alongside the potential that eVOCs have as biomarkers of air pollution exposure and future perspectives on clinical breath sampling are provided.
•Recent advances in the clinical deployment of eVOC analyses are reviewed.•The role oxidative stress plays in producing proposed biomarkers for disease diagnosis is discussed.•Focus is placed on quantitative studies and targeted analyses.•The potential of eVOCs as biomarkers of air pollution exposure is highlighted.•Perspectives on the future of clinical breath sampling are provided.
Using a specifically designed chemical tracer to indirectly measure local atmospheric hydroxyl radical (OH) concentrations is a very appealing concept. Such a tracer will provide information on the ...amount of OH a tracer encounters, as it moves through the urban environment and provide a stringent test of models. However, to date an outdoor experiment such as this has not been conducted. This article discusses the reasons why this is so and examines the feasibility of using tracers to measure integrated urban OH levels over short (≤1 km) distances.
This paper presents the results of a study examining whether the flooding of pasture by rivers gives rise to higher PCDD/F and PCB concentrations in cows' milk. Over 180 milk, soil, and grass ...samples, taken from 38 farms across 3 different river systems (River Dee, Trent, and Doe Lea/Rother/Don) in the United Kingdom, were analyzed for PCDD/Fs and PCBs. The concentrations were compared between flood-prone farms, where the animals had access to pasture that is often flooded, and control farms where the land does not flood. The results indicated that concentrations of PCDD/Fs and PCBs in cows' milk were higher in samples taken from farms prone to flooding, but only from the river systems flowing through industrial and urban areas. Raised levels of PCDD/F and PCBs were also found in soil and grass from farms prone to flooding providing strong corroborative evidence that the higher concentrations in cows' milk from such areas is likely to be due to the ingestion of contaminated grass and soil. Overall, the results provide strong evidence that flooding of pastureland can indeed result in elevated concentrations of PCDD/Fs and PCBs in milk from the farms so affected.
Pulmonary aspergillosis can cause serious complications in people with a suppressed immune system. Volatile metabolites emitted by
Aspergillus
spp. have shown promise for early detection of ...pathogenicity. However, volatile profiles require further research, as effective headspace analysis methods are required for extended chemical coverage of the volatome; in terms of both very volatile and semi-volatile compounds. In this study, we describe a novel adaptable sampling method in which fungal headspace samples can be sampled continuously throughout a defined time period using both active (pumped) and passive (diffusive) methods, with the capability for samples to be stored for later off-line analysis. For this method we utilise thermal desorption-gas chromatography-mass spectrometry to generate volatile metabolic profiles using
Aspergillus fumigatus
as the model organism. Several known fungal-specific volatiles associated with secondary metabolite biosynthesis (including α-pinene, camphene, limonene, and several sesquiterpenes) were identified. A comparison between the wild-type
A. fumigatus
with a phosphopantetheinyl transferase null mutant strain (
ΔpptA
) that is compromised in secondary metabolite synthesis, revealed reduced production of sesquiterpenes. We also showed the lack of terpene compounds production during the early growth phase, whilst pyrazines were identified in both early and late growth phases. We have demonstrated that the fungal volatome is dynamic and it is therefore critically necessary to sample the headspace across several time periods using a combination of active and passive sampling techniques to analyse and understand this dynamism.
Culture headspace sampling and analysis of
aspergillus fumigatus
volatile metabolites by TD-GC-MS.
Abstract only
2589
Background: Accurate determination of GFR is essential for correct dosing of carboplatin, the standard adjuvant therapy for stage 1 seminoma. Isotopic methods (e.g. 51Cr-EDTA) ...remain the gold standard for determination of GFR. However, the use of eGFR could reduce the need for such isotope studies. As novel formulae to estimate GFR such as CKD-EPI and MDRD4 have improved the assessment of renal function in non-oncological settings, we investigated their utility for carboplatin dosing. Methods: 115 patients (pts) (mean age 40.3, std dev. 10.1) who received adjuvant carboplatin for stage 1 seminoma at our institution between 2007-2012 were identified. All pts underwent 51Cr-EDTA measurement of GFR with carboplatin dose calculated using the Calvert formula, based on GFR uncorrected for body surface area (BSA). Theoretical carboplatin doses were then calculated using eGFR values obtained using the CKD-EPI and MDRD4 formulae with additional calculation to uncorrect for BSA. Creatinine clearance was calculated by Cockcroft-Gault (CG) formula. For each pt the carboplatin doses calculated by eGFR were compared with the actual dose calculated by the gold-standard method; a difference of less than 10% was considered acceptable. Results: The Table shows the percentage of pts who would have received an equivalent carboplatin dose using each eGFR formula compared to the dose calculated using 51Cr-EDTA. The CKD-EPI formula performed best with 58.9% of pts receiving within 10% of the correct dose. Pts predicted to be underdosed by CKD-EPI eGFR were more likely to be obese (BMI >30) (p=0.01); there were no predictors of the 18.8% who would have received an excess dose. Conclusions: Our data support further evaluation of the CKD-EPI formula but highlight the clinically significant variances in carboplatin dosing when using non-isotopic methods of GFR estimation. Table: see text
SUPPLEMENT Wood, Curtis R.; Arnold, Samantha J.; Balogun, Ahmed A. ...
Bulletin of the American Meteorological Society,
07/2009, Letnik:
90, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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