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Psimadas D.,Technological Educational Institute of Athens | Psimadas D.,Institute of Nuclear and Radiological Science and Technology | Baldi G.,CERICOL | Ravagli C.,CERICOL | And 5 more authors.
Nanotechnology | Year: 2014

Metal oxide nanoparticles, hybridized with various polymeric chemicals, represent a novel and breakthrough application in drug delivery, hyperthermia treatment and imaging techniques. Radiolabeling of these nanoformulations can result in new and attractive dual-imaging agents as well as provide accurate in vivo information on their biodistribution profile. In this paper a comparison study has been made between two of the most promising hybrid core-shell nanosystems, bearing either magnetite (Fe3O4) or cobalt ferrite (CoFe2O4) cores, regarding their magnetic, radiolabeling, hyperthermic and biodistribution properties. While hyperthermic properties were found to be affected by the metal-core type, the radiolabeling ability and the in vivo fate of the nanoformulations seem to depend critically on the size and the shell composition. © 2014 IOP Publishing Ltd. Source

Psimadas D.,Technological Educational Institute of Athens | Tsotakos T.,Technological Educational Institute of Athens | Tsotakos T.,Institute of Nuclear and Radiological Science and Technology | Fragogeorgi E.,Technological Educational Institute of Athens | Loudos G.,Technological Educational Institute of Athens
Current Medicinal Chemistry | Year: 2015

Passage into the brain has always been a major challenge for medicine in order to treat malfunctions of the central nervous system (CNS). The blood-brain-barrier (BBB) is a physical obstacle that controls the entrance of substances-including pharmaceuticals-into the brain. The application of nanotechnology in medicine, namely nanomedicine, is rapidly evolving and opens new prospects for brain imaging and drug delivery into the brain. Nanomedicine when combined with nuclear medicine can offer new, promising and innovative means towards this direction through radiolabeled nanoparticles. Nanoparticles radiolabeled with β-, γ- or β+-emitters can cross the BBB and play major role in CNS imaging and/or drug delivery. © 2015 Bentham Science Publishers. Source

Mendes L.,Institute of Nuclear and Radiological Science and Technology | Mendes L.,University of Aegean | Eleftheriadis K.,Institute of Nuclear and Radiological Science and Technology | Biskos G.,Technical University of Delft | Biskos G.,The Cyprus Institute
Journal of Aerosol Science | Year: 2016

Volatility Tandem Differential Mobility Analysers (VTDMAs) are widely used for determining the volatile and refractory fractions and thus the mixing state of aerosols particles. A three-channel VTDMA consisting of two thermodenuders (TDs) with distinct designs (i.e., the NanoTD, having a straight tube design, and a coiled TD; cTD) and a by-pass line was built and fully characterized. Both TDs were tested using laboratory-generated aerosol particles (single compound and core-shell particles) as well as atmospheric aerosols observed at an urban background station. The NanoTD exhibited high particle penetration efficiency and negligible thermophoretic losses, making it advantageous for ultrafine particle analysis, especially in environments with low particle concentration. The cTD allows longer particle residence time for the same flow rate, resulting in higher particle volatilization in some cases. Higher particle losses in this TD, both thermophoretic and diffusional, pose a limitation when dealing with low particle concentrations.The difference in the performance between the thermodenuders was only noticed at intermediate temperatures, at which particle volume loss becomes more pronounced. These temperatures vary among aerosols, since the volatilization rate depends on the chemical complexity and size of the particles sampled. Differences in the aerosol volume fraction remaining after heating with the two TD designs exhibited a maximum of 20% for single-compound particles and 12% for urban background aerosols. Measurements using core-shell particles yielded differences of up to 21% in particle volatilization, independently of particle size, when comparing the system using either of the two TD designs. Similar results were obtained with the two TD designs at higher operating temperatures (e.g., 230. °C), indicating that at this temperature most of the material on the particles was evaporated. © 2015 The Authors. Source

Eleftheriadis K.,Institute of Nuclear and Radiological Science and Technology | Ochsenkuhn K.M.,National Technical University of Athens | Lymperopoulou T.,National Technical University of Athens | Karanasiou A.,Institute of Nuclear and Radiological Science and Technology | And 3 more authors.
Atmospheric Environment | Year: 2014

The variability of common aerosol species in large Metropolitan urban areas is a major air quality issue with strong health impacts of large populations. PM10 and PM2.5 particulate matter samples were obtained at three sites characteristic of industrial, urban traffic and sub-urban residential areas in the Athens basin. Samples were analysed for anions (Cl-, NO3 -, SO4 2-) and cations (K+, Na+, Ca2+, Mg2+, NH4 +) using ion chromatography. The spatial and temporal variability for the particulate matter (PM) concentration mass and water-soluble ionic species concentrations for the investigated sites were studied. Mean PM fine concentration levels were 20% higher at the industrial and the central urban areas compared to those in the suburban area (24.2μg/m3). The mean values for the coarse fraction at those two sites were two to three times higher compared to those at the suburban site (12.4μg/m3). Comparable concentration levels of most species were observed in all areas, while SO4 2- and NO3 - differ at a significant level. Furthermore, the average size distributions of the mass and individual ions at the suburban site (NCSR Demokritos) showed a bimodal size distribution. SO4 2- and NH4 + have their main peak in the fine fraction while NO3 - showed equal distribution on the fine and coarse mode. Good correlation was found for SO4 2- and NO3 - with Ca2+ and Na+ with Cl- for the coarse fraction in the industrial area. NH4 + was closely correlated with SO4 2- in the fine particles and in all areas. For the urban site the best correlations in coarse particulates were reported between Na+/Mg2+-Cl-, Ca2+/Mg2+-SO4 2-, explained by neutralization of acidic aerosol by soil dust and sea salt in the coarse fraction. Moreover, time weighted concentrations roses at the industrial and urban sites, showed no significant directional dependence, indicating either uniform generation of mainly the coarse species within the metropolitan area or major influence of the regional background for the fine aerosol species. © 2014. Source

Vlachogiannis D.,Institute of Nuclear and Radiological science and Technology Energy and Safety | Sfetsos A.,Institute of Nuclear and Radiological science and Technology Energy and Safety | Gounaris N.,Institute of Nuclear and Radiological science and Technology Energy and Safety | Papadopoulos A.,Institute of Nuclear and Radiological Science and Technology
International Journal of Environment and Pollution | Year: 2012

The heavy urbanisation of great cities has caused immense concern to societies due to air quality degradation and adverse changes in local climates such as abnormally high temperatures. Due to the growing demand for renewable energy resources and electrical power generation, the installation of photovoltaic (PV) panels on building roofs and other available open spaces has advanced in the recent years. Such applications are translated to land use and land cover modifications with respect to the existing situation. This work attempts to investigate the application of PVs in the city of Athens (Greece) and estimate computationally the subsequent results in maximum temperatures and wind velocities mainly during hot weather events. Those events were identified using meteorological data available from the National Centres for Environmental Prediction (NCEP) global forecasting system (GFS). Land use changes due to photovoltaic canopies have been translated into changes in surface albedo and roughness, specific heat capacities, thermal properties and evapo-transpiration in the input files of the domain of Athens (1 ×1 km2) of the modelling system (Mesoscale Model 5, MM5). The model results revealed noticeable changes in the temperature and wind fields when applying the scenario of installing PV panels in the urban canopy of the city. © 2012 Inderscience Enterprises Ltd. Source

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