Investigation of dosimetry in four human head models for planar monopole antenna with a coupling feed for LTE/WWAN/WLAN internal mobile phone

The objective of the present study is to evaluate the Specific Absorption Rate (SAR) within the human head model exposed to the radiation of planar monopole antenna with T-shaped coupling feed and an inductive shorting strip. The presented design has a compact structure, a planar configuration and occupying a small size of 36×20mm2. Two wide bands can be generated by the proposed antenna 546 MHz (734-1280 MHz) and 1066 MHz (1934-3000 MHz) for the LTE/WWAN/WLAN internal mobile phone. The antenna performance parameters comprising return loss, radiation patterns, and gain are discussed. In this research work four different human head models have been implemented: homogenous spherical head, spherical seven layer model, Specific Anthropomorphic Mannequin (SAM) phantom and HUGO human head model. On the other hand the effects of operating frequency and gap distance between the mobile phone antenna and the human head model on distributions of the SAR inside the human head are investigated. All the simulations are done for three different distances between the antenna and the head model (5 mm, 10 mm and 20 mm). Moreover, the SAR levels for the head tissues are calculated in accordance to the two currently accepted standards: Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP)

Synthesis, reactivity and structural studies of selenide bridged carboranyl compounds

Reaction of the lithium salt Li[1-R-1,2-closo-C2B10H10] with selenium under mild conditions, followed by hydrolysis gave the diselenide compound (1-Se-2-R-1,2-closo-C2B10H10)2 in contrast to the well-reported mercapto compounds 1-SH-2-R-1,2-closo-C2B10H10 obtained using a similar synthetic procedure. Details for the preparation and X-ray structural characterisation of the new compounds (2-Me-1,2-closo-C2B10H10)2Se (1), (1-Se-2-R-1,2-closo-C2B10H10)2 (R = Me,2, Ph, 3) are specified. To further explore the mechanism of the dimerization reaction, the complex [Au(1-Se-2-Me-1,2-closo- C2B10H10)(PPh3)] 4 was synthesized, confirming the existence of the intermediate Li[1-Se-2-R-1,2-closo-C2B10H10] at the early stages of the reaction before selenium oxidation. Theoretical calculations and cyclic voltammetry (CV) studies were carried out to compare the bonding nature of the sulfur and the selenium analog compounds. It was determined that diselenides have a higher tendency to reduce with respect to the disulfides and all chalcogen atoms were found to be positively charged

The Role of Surfactants on Cloud Formation: Surfactants in PM1 Aerosols from Urban to Remote Regions and Correlations with Cloud Occurrence

SSCI-VIDE+ATARI+DSG:LFI:CFE:BNOInternational audienceSurface tension is a key parameter in the Köhler equation describing cloud droplet formation, but which has been ignored for many years, mostly because of the lack of information on the surfactants present in aerosols and their effects on the surface tension. For this reason we have recently developed methods to extract the total surfactant fraction from aerosols (= sum of all the components affecting their surface tension), measure their concentrations, and determine the overall surface tension isotherm of the aerosols. This work presents the application of these methods to PM1 aerosols from different regions; Lyon, France (urban site, 55 samples), Rozgonica, Croatia (coastal site, 17 samples), and Pallas, Finland (remote site, 237 samples), and the first results on their surfactants and how much they might contribute to cloud formation.The results show that, in spite of large differences in the concentration and size distribution of aerosols in these different regions, the average molar concentrations of anionic, cationic and non-ionic surfactants inside the PM1 particles displayed similar trends: non-ionic surfactants represented 60 to 70 % of the total surfactant concentration, anionic ones 20 to 35 %, while cationic surfactants were negligible. However, large differences were observed in the Critical Micelle Concentration (CMC), the key point of the surface tension isotherm: the CMC of surfactants in remote aerosols was nearly 10 times lower than that in urban aerosols (1.7 x 10-4 M and 9.3 x 10-4 M, respectively) evidencing very different molecular structures and the greater cloud-forming efficiency of the surfactants from remote regions.In a second study, the potential role of surfactants on cloud formation was explored by comparing the analysis of the surfactants in PM1 aerosols (237 samples) with cloud occurrence over 9 months (257 clouds) at the remote Pallas Supersite of the Finnish Meteorological Institute in Finland. Statistical analyses (Canonical Correlation Analysis, CCA, and regression analyses) were applied to the data and revealed strong co-dependencies between the surfactant properties (ratio of concentration over CMC, C/CMC, quantifying the surfactant efficiency) and cloud frequency. As no such co-dependency was found between the surfactants and any of the other cloud-relevant variables (temperature, relative humidity, aerosol particle radius, and hygroscopic composition) these results suggested a direct, physical connection between the surfactants properties in PM1 and cloud properties. This connection was further confirmed by time-dependent analyses showing that each increase in surfactant efficiency observed over a 48h-period coincided with an increase in cloud frequency. These results are the first atmospheric evidence for a causality relationship between surfactants in PM1 aerosols and cloud formatio

The Role of Surfactants on Cloud Formation: Surfactants in PM1 Aerosols from Urban to Remote Regions and Correlations with Cloud Occurrence

SSCI-VIDE+ATARI+DSG:LFI:CFE:BNOInternational audienceSurface tension is a key parameter in the Köhler equation describing cloud droplet formation, but which has been ignored for many years, mostly because of the lack of information on the surfactants present in aerosols and their effects on the surface tension. For this reason we have recently developed methods to extract the total surfactant fraction from aerosols (= sum of all the components affecting their surface tension), measure their concentrations, and determine the overall surface tension isotherm of the aerosols. This work presents the application of these methods to PM1 aerosols from different regions; Lyon, France (urban site, 55 samples), Rozgonica, Croatia (coastal site, 17 samples), and Pallas, Finland (remote site, 237 samples), and the first results on their surfactants and how much they might contribute to cloud formation.The results show that, in spite of large differences in the concentration and size distribution of aerosols in these different regions, the average molar concentrations of anionic, cationic and non-ionic surfactants inside the PM1 particles displayed similar trends: non-ionic surfactants represented 60 to 70 % of the total surfactant concentration, anionic ones 20 to 35 %, while cationic surfactants were negligible. However, large differences were observed in the Critical Micelle Concentration (CMC), the key point of the surface tension isotherm: the CMC of surfactants in remote aerosols was nearly 10 times lower than that in urban aerosols (1.7 x 10-4 M and 9.3 x 10-4 M, respectively) evidencing very different molecular structures and the greater cloud-forming efficiency of the surfactants from remote regions.In a second study, the potential role of surfactants on cloud formation was explored by comparing the analysis of the surfactants in PM1 aerosols (237 samples) with cloud occurrence over 9 months (257 clouds) at the remote Pallas Supersite of the Finnish Meteorological Institute in Finland. Statistical analyses (Canonical Correlation Analysis, CCA, and regression analyses) were applied to the data and revealed strong co-dependencies between the surfactant properties (ratio of concentration over CMC, C/CMC, quantifying the surfactant efficiency) and cloud frequency. As no such co-dependency was found between the surfactants and any of the other cloud-relevant variables (temperature, relative humidity, aerosol particle radius, and hygroscopic composition) these results suggested a direct, physical connection between the surfactants properties in PM1 and cloud properties. This connection was further confirmed by time-dependent analyses showing that each increase in surfactant efficiency observed over a 48h-period coincided with an increase in cloud frequency. These results are the first atmospheric evidence for a causality relationship between surfactants in PM1 aerosols and cloud formatio

Concentrations and Adsorption Isotherms for Amphiphilic Surfactants in PM1 Aerosols from Different Regions of Europe

SSCI-VIDE+ATARI+BNO:LFI:CFE:DSGInternational audience--