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)

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--

Variations in tropospheric submicron particle size distributions across the European continent 2008–2009

Cluster analysis of particle number size distributions from background sites across Europe is presented. This generated a total of nine clusters of particle size distributions which could be further combined into two main groups, namely: a south-to-north category (four clusters) and a west-to-east category (five clusters). The first group was identified as most frequently being detected inside and around northern Germany and neighbouring countries, showing clear evidence of local afternoon nucleation and growth events that could be linked to movement of air masses from south to north arriving ultimately at the Arctic contributing to Arctic haze. The second group of particle size spectra proved to have narrower size distributions and collectively showed a dependence of modal diameter upon the longitude of the site (west to east) at which they were most frequently detected. These clusters indicated regional nucleation (at the coastal sites) growing to larger modes further inland. The apparent growth rate of the modal diameter was around 0.6–0.9 nm h−1. Four specific air mass back-trajectories were successively taken as case studies to examine in real time the evolution of aerosol size distributions across Europe. ~While aerosol growth processes can be observed as aerosol traverses Europe, the processes are often obscured by the addition of aerosol by emissions en route. This study revealed that some of the 24 stations exhibit more complex behaviour than others, especially when impacted by local sources or a variety of different air masses. Overall, the aerosol size distribution clustering analysis greatly simplifies the complex data set and allows a description of aerosol aging processes, which reflects the longer-term average development of particle number size distributions as air masses advect across Europe.JRC.C.5-Air and Climat

Number size distributions and seasonality of submicron particles in Europe 2008–2009

Two years of harmonized aerosol number size distribution data from 24 European field monitoring sites have been analysed. The results give a comprehensive overview of the European near surface aerosol particle number concentrations and number size distributions between 30 and 500 nm of dry particle diameter. Spatial and temporal distribution of aerosols in the particle sizes most important for climate applications are presented. We also analyse the annual, weekly and diurnal cycles of the aerosol number concentrations, provide log-normal fitting parameters for median number size distributions, and give guidance notes for data users. Emphasis is placed on the usability of results within the aerosol modelling community.JRC.H.2-Air and Climat

Chiral (LH)2L2Cu3 trinuclear paramagnetic nodes in octacyanidometalate-bridged helical chains.

Trinuclear chiral (LH)2L2Cu3 (LH = 1,3-diamino-2-propanol, bdapH) assemblies linked by octacyanidometalate(IV) form isostructural one-dimensional (1D) chains consisting of right- and left-handed helixes arranged in an alternate manner: [(bdapH)2(bdap)2Cu(II)3][M(IV)(CN)8]*H2O (M = Mo 1, W 2). Each chain displays helicity with a long pitch around 17.2 Å. The direction of the helix rotation is strictly connected with the conformation of the (LH)2L2Cu3 unit. Right-handed helixes are based on Δ-S,S-(LH)2L2Cu3, whereas left-handed ones contain Λ-R,R-(LH)2L2Cu3 units. Magnetic studies reveal antiferromagnetic interactions through alkoxo-bridges inside trinuclear Cu(II) nodes leading to an ST = 1/2 ground state for both assemblies