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Georgakilas V.,Institute of Material Science | Bourlinos A.B.,Institute of Material Science | Zboril R.,Palacky University | Steriotis T.A.,Institute of Physical Chemistry | And 4 more authors.
Chemical Communications

Graphene sheets derived from dispersion of graphite in pyridine were functionalised by the 1,3 dipolar cycloaddition of azomethine ylide. The organically modified graphene sheets are easily dispersible in polar organic solvents and water, and they are extensively characterised using several spectroscopic and microscopy techniques. © 2010 The Royal Society of Chemistry. Source

Diapouli E.,Institute of Nuclear Technology and Radiation Protection | Papamentzelopoulou A.,NTUA | Chaloulakou A.,NTUA
Global Nest Journal

The scope of the present work was to examine exposure to airborne particulate matter (PM) at a marble cutting and treatment facility. Measurements were conducted inside all sections of the facility, as well as at selected outdoor locations. PM10 concentrations were monitored continuously, with a 1-min time resolution, by the use of DustTrak (Model 8520, TSI, Inc.). Mean PM10 concentration levels during cutting operations were measured equal to 997 μg m-3, when all machines were in use and 710 μg m-3, when only half of the machines were functioning. Higher levels were measured at the artistic department, where marble is cut and processed manually (mean PM10 concentration equal to 3,860 during a heavy cutting procedure and 1,000 μg m-3 during a light duty period). When sampling was conducted next to the workers during the cutting process, mean personal exposure reached up to 63,000 μg m-3. The use of water during cutting operation was found to effectively decrease PM emissions. Significant concentrations were also measured at the different administrative offices. The highest levels (mean concentration equal to 220 μg m-3) were measured at the accounting office which is located at ground level, in close vicinity to the cutting section. © 2013 Global NEST Printed in Greece. All rights reserved. Source

Kopanakis I.,Technical University of Crete | Eleftheriadis K.,Institute of Nuclear Technology and Radiation Protection | Mihalopoulos N.,University of Crete | Lydakis-Simantiris N.,Technological Educational Institute of Crete | And 4 more authors.
Atmospheric Research

Particulate matter (PM 10, PM 2.5) measurements were performed during the period 2003-2009 at the Akrotiri monitoring station (suburban/rural) on the island of Crete, Greece. Concurrent measurements of PM 10 size distribution/chemical composition were also performed at selected time intervals to determine the PM sources in the region and the factors controlling their levels. Using a beta radiation attenuation monitor, the mean PM 10 concentration during the measuring period (15.04.2003-31.12.2009) was equal to 36.1±9.5μg/m 3, whereas the PM 2.5 concentration was equal to 23.6±5.8μg/m 3. Back trajectories showed that the dominant air mass origin was from North and Northwest Europe but the intrusion of southern air masses lead to elevated PM concentrations due to Saharan dust events. The 24-h EU limit value of 50μg/m 3 (PM 10) was exceeded approximately 13.5% during the measured period. Furthermore, the PM 10 mass size distribution of metals, ions and organic carbon/elemental carbon (OC/EC) was characterized using a 9-stage Andersen non-viable impactor and a gravimetric sequential PM 10 sampler during two selected periods. The mean PM 10 concentration during the first sampling period was equal to 28.3±12.4μg/m 3 (10.08.2007-28.08.2007), whereas during the second sampling period (09.07.2008-19.07.2008) was 41.6±14.0μg/m 3. The measurements showed a bimodal size distribution for the aerosol mass concentration. PM 2.1 accounted for 41.0% and 37.2% for PM 10 during the two periods respectively. Over the measurement campaigns ions dominated the PM 10 mass (50-80%) with the organic mass and metals comprising the major part of the rest. The OC concentration was equal to 2.3±1.2μg/m 3, whereas the EC concentration was equal to 0.8±0.2μg/m 3. Finally, black carbon concentrations were measured in August 2007 with an aethalometer. The mean daily value of black carbon was 0.69±0.22μg/m 3. The measurements showed that the PM values measured at the station correspond to a background/rural station in the region and are in agreement with other measurements in the Eastern Mediterranean region. © 2011 Elsevier B.V.. Source

Glytsos T.,Technical University of Crete | Ondracek J.,Technical University of Crete | Ondracek J.,Czech Institute of Chemical Process Fundamentals | Dzumbova L.,Technical University of Crete | And 3 more authors.
Indoor and Built Environment

Aerosol mass concentration (PM10, PM2.5) measurements were conducted in the workplace of a detergent industry for two time periods during July 2005 and January 2006, using two portable real-time photometric monitors. The results showed increased mass concentrations both for PM10 and PM2.5 particles during the detergent production periods. The differences in the concentrations of the PM10 and PM2.5 particles were used to determine the corresponding mass concentrations of coarse particles and these values were then used to evaluate the diurnal variation both for fine and coarse particles. An indoor mass balance model was applied to estimate the aerosol mass emission rates, as well as the particle loss rates due to all removal processes. A good agreement was obtained between the model predictions and the measurements. The indoor model can be used in conjunction with experimental measurements for the evaluation of aerosol mass concentrations in industrial sites. © The Author(s) 2013. Source

Molgaard B.,University of Helsinki | Birmili W.,Leibniz Institute for Tropospheric Research | Clifford S.,Queensland University of Technology | Massling A.,University of Aarhus | And 8 more authors.
Journal of Aerosol Science

In this study we evaluated a forecast model for urban aerosol number concentrations against measurements made at five European cities: Helsinki, Stockholm, Copenhagen, Leipzig, and Athens. This model requires a learning data set with particle number concentrations, traffic densities and local meteorology. Additionally, in the forecasting process it requires the same parameters from the past week and forecasted values of weather and traffic. The model performance was tested based on the R2, index of agreement (IA), mean square error (MSE), and bias. We tested three modelling approaches: one with fixed parameterisation and two with optimisations based on either the Deviance or the Akaike Information Criterion. Based on the hourly one-day forecasts at the urban background sites the IA ranged from 0.65 to 0.80 for accumulation mode particles and from 0.68 to 0.87 for ultrafine particles. The model performance was the best for Helsinki and Stockholm and the worst for Leipzig and Copenhagen. The main reason is the more pronounced diurnal variation in Helsinki and Stockholm. Another reason is that the traffic data for Leipzig and Copenhagen were not as complete as for the other cities. The three approaches yielded similar model performances, hence we conclude that the simplest one based on a fixed parametrisation is to be preferred. © 2013 Elsevier Ltd. Source

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