Showing papers by "George Biskos published in 2018"
TL;DR: Tests did not show any antibacterial effects of Au nanoparticles (NPs) as a result of their negligible diffusivity through the culture media, and Ag NPs exhibited a strong antimicrobial activity that was independent of their size.
Abstract: The use of disc diffusion susceptibility tests to determine the antibacterial activity of engineered nanoparticles (ENPs) is questionable because their low diffusivity practically prevents them from penetrating through the culture media. In this study, we investigate the ability of such a test, namely the Kirby-Bauer disc diffusion test, to determine the antimicrobial activity of Au and Ag ENPs having diameters from 10 to 40 nm on Escherichia coli cultures. As anticipated, the tests did not show any antibacterial effects of Au nanoparticles (NPs) as a result of their negligible diffusivity through the culture media. Ag NPs on the other hand exhibited a strong antimicrobial activity that was independent of their size. Considering that Ag, in contrast to Au, dissolves upon oxidation and dilution in aqueous solutions, the apparent antibacterial behavior of Ag NPs is attributed to the ions they release. The Kirby-Bauer method, and other similar tests, can therefore be employed to probe the antimicrobial activity of ENPs related to their ability to release ions rather than to their unique size-dependent properties.
50 citations
TL;DR: In this article, the vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) observations and in situ measurements using an optical particle counter on board a UAV during moderate and weak Saharan dust episodes were compared.
Abstract: . In situ measurements using unmanned aerial vehicles (UAVs) and
remote sensing observations can independently provide dense
vertically resolved measurements of atmospheric aerosols, information which
is strongly required in climate models. In both cases, inverting the recorded
signals to useful information requires assumptions and constraints, and this
can make the comparison of the results difficult. Here we compare, for the
first time, vertical profiles of the aerosol mass concentration derived from
light detection and ranging (lidar) observations and in situ measurements
using an optical particle counter on board a UAV during moderate and
weak Saharan dust episodes. Agreement between the two measurement methods was
within experimental uncertainty for the coarse mode (i.e. particles having
radii >0.5 µm ), where the properties of dust particles can be assumed
with good accuracy. This result proves that the two techniques can be used
interchangeably for determining the vertical profiles of aerosol
concentrations, bringing them a step closer towards their systematic
exploitation in climate models.
39 citations
TL;DR: In this paper, a new method for increasing the detection efficiency of condensation particle counters (CPCs) for sub-2-nm particles, which relies mainly on controlling the spatial distribution of the supersaturation profile by simply modifying the operating temperatures of the CPC.
29 citations
TL;DR: The increasing need for engineered alloy nanoparticles (NPs) in diverse fields has spurred efforts to explore efficient/green synthesis methods as mentioned in this paper, in this respect, spark ablation provides a scalable...
Abstract: The increasing need for engineered alloy nanoparticles (NPs) in diverse fields has spurred efforts to explore efficient/green synthesis methods. In this respect, spark ablation provides a scalable ...
25 citations
TL;DR: The results suggest that LaFeSi nanoalloys can be used to exploit the magnetocaloric effect near room temperature; such a finding can lead to the creation of unique multicomponent materials for energy conversion, thus helping toward the realization of a sustainable energy economy.
Abstract: Using the magnetocaloric effect in nanoparticles holds great potential for efficient refrigeration and energy conversion. The most promising candidate materials for tailoring the Curie temperature to room temperature are rare-earth-based magnetic nanoalloys. However, only few high-nuclearity lanthanide/transition-metal nanoalloys have been produced so far. Here we report, for the first time, the observation of magnetic response in spark-produced LaFeSi nanoalloys. The results suggest that these nanoalloys can be used to exploit the magnetocaloric effect near room temperature; such a finding can lead to the creation of unique multicomponent materials for energy conversion, thus helping toward the realization of a sustainable energy economy.
25 citations
TL;DR: In this article, a UAV-based air quality monitoring using airborne platforms is described, which is becoming easier, less expensive, and safer to operate on a routine basis, as UAVs are becoming easier and less expensive to operate.
Abstract: Air quality monitoring using airborne platforms is rapidly gaining ground as unmanned aerial vehicles (UAVs) are becoming easier, less expensive, and safer to operate on a routine basis. To facilit...
24 citations
TL;DR: The evolution of particle volatility and size throughout the day provide additional support that most nanoparticles in the metro station originate from outdoor urban air.
20 citations
TL;DR: In this article, the hygroscopic properties of KBr, KCl, and KI nanoparticles having diameters from 8 to 60nm were measured using a tandem Differential Mobility Analyzer.
Abstract: The hygroscopic properties of KBr, KCl, and KI nanoparticles having diameters from 8 to 60 nm were measured using a tandem Differential Mobility Analyzer. In all cases, the deliquescence and efflor...
10 citations
TL;DR: Long-term measurements of PM2.5 mass concentrations and aerosol particle size distributions, as well as hygroscopicity measurements conducted over one year at Cabauw, The Netherlands, are compiled here to provide a comprehensive dataset for understanding the trends and annual variabilities of the atmospheric aerosol in the region.
6 citations
TL;DR: In this paper, the vertical profiles of the aerosol mass concentration derived from Light Detection And Ranging (lidar) observations and in-situ measurements using an Optical Particle Counter (OPC) onboard a UAV during moderate and weak Saharan dust episodes were compared.
Abstract: In-situ measurements using Unmanned Aerial Vehicles (UAVs) and remote sensing observations can independently provide dense vertically-resolved measurements of atmospheric aerosols; information which is highly required in climate models. In both cases, inverting the recorded signals to useful information requires assumptions and constraints, and this can make the comparison of the results difficult. Here we compare, for the first time, vertical profiles of the aerosol mass concentration derived from Light Detection And Ranging (lidar) observations and in-situ measurements using an Optical Particle Counter (OPC) onboard a UAV during moderate and weak Saharan dust episodes. Agreement between the two measurement methods was within experimental uncertainty for the coarse-mode (i.e., particles having radii > 0.5 μm) where the properties of dust particles can be assumed with good accuracy. This result proves that the two techniques can be used interchangeably for determining the vertical profiles of the aerosol concentrations, bringing them a step closer towards their systematic exploitation in climate models.