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- Toledano, C., et al.
(författare)
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Overview of sun photometer measurements of aerosol properties in Scandinavia and Svalbard
- 2012
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 52, s. 18-28
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Tidskriftsartikel (refereegranskat)abstract
- An overview on the data of columnar aerosol properties measured in Northern Europe is provided. Apart from the necessary data gathered in the Arctic, the knowledge of the aerosol loading in nearby areas (e.g. sub-Arctic) is of maximum interest to achieve a correct analysis of the Arctic aerosols and transport patterns. This work evaluates data from operational sites with sun photometer measurements belonging either to national or international networks (AERONET, GAW-PFR) and programs conducted in Scandinavia and Svalbard. We enumerate a list of sites, measurement type and periods together with observed aerosol properties. An evaluation and analysis of aerosol data was carried out with a review of previous results as well. Aerosol optical depth (AOD) and Angstrom exponent (AE) are the current parameters with sufficient long-term records for a first evaluation of aerosol properties. AOD (500 nm) ranges from 0.08 to 0.10 in Arctic and sub-Arctic sites (Ny-Alesund: 0.09; Andenes: 0.10; Sodankyla: 0.08), and it is somewhat higher in more populated areas in Southern Scandinavia (AOD about 0.10-0.12 at 500 nm). On the Norwegian coast, aerosols show larger mean size (AE = 1.2 at Andenes) than in Finland, with continental climate (AE = 1.5 at Sodankyla). Columnar particle size distributions and related parameters derived from inversion of sun/sky radiances were also investigated. This work makes special emphasis in the joint and collaborative effort of the various groups from different countries involved in this study. Part of the measurements presented here were involved in the IPY projects Polar-AOD and POLARCAT.
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| 2. |
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| 3. |
- Gozem, Samer, et al.
(författare)
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Shape of Multireference, Equation-of-Motion Coupled-Cluster, and Density Functional Theory Potential Energy Surfaces at a Conical Intersection
- 2014
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Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 10:8, s. 3074-3084
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Tidskriftsartikel (refereegranskat)abstract
- We report and characterize ground-state and excited-state potential energy profiles using a variety of electronic structure methods along a loop lying on the branching plane associated with a conical intersection (Cl) of a reduced retinal model, the penta-2,4-dieniminium cation (PSB3). Whereas the performance of the equation-of-motion coupled-duster, density functional theory, and multireference methods had been tested along the excited- and ground-state paths of PSB3 in our earlier work, the ability of these methods to correctly describe the potential energy surface shape along a CI branching plane has not yet been investigated. This is the focus of the present contribution. We find, in agreement with earlier studies by others, that standard time-dependent DFT (TDDFT) does not yield the correct two-dimensional (i.e., conical) crossing along the branching plane but rather a one-dimensional (i.e., linear) crossing along the same plane. The same type of behavior is found for SS-CASPT2(IPEA=0), SS-CASPT2(IPEA=0.25), spin-projected SF-TDDFT, EOM-SF-CCSD, and, finally, for the reference MRCISD+Q method. In contrast, we found that MRCISD, CASSCF, MS-CASPT2(IPEA=0), MS-CASPT2(IPEA=0.25), XMCQDPT2, QD-NEVPT2, non-spin-projected SF-TDDFT, and SI-SA-REKS yield the expected conical crossing. To assess the effect of the different crossing topologies (i.e., linear or conical) on the PSB3 photoisomerization efficiency, we discuss the results of 100 semiclassical trajectories computed by CASSCF and SS-CASPT2(IPEA=0.25) for a PSB3 derivative. We show that for the same initial conditions, the two methods yield similar dynamics leading to isomerization quantum yields that differ by only a few percent.
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| 4. |
- Midander, Klara, et al.
(författare)
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Bioaccessibility of FERRO-chromium and ferrosilicon-chromium particles compared to pure metals and stainless steel-Aspects of human exposure
- 2010
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Ingår i: Proceedings of the 12th International Ferroalloys Congress: Sustainable Future. - 9789529273409 ; , s. 43-51
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Konferensbidrag (refereegranskat)abstract
- Product safety legislation requires that industry indentifies and demonstrates any human risks associated with the manufacture and use of products which are placed on the market throughout their entire life cycle. This process involves detailed assessment of potential hazards of the products/material related to health effect endpoints, and requires accurate generation and interpretation of data which can be used to determine essential characteristics of the material. Temporary or permanent adverse health effects depend either on the shape or physical characteristics of the particles, and/or on chemical interactions with the particle surface upon human exposure. Since alloys represent the most significant and widespread use of many engineering metals, it is important to develop a detailed understanding of the characteristics and behaviour of this group of materials with a minimum dependence on in-vivo testing. The aim of this presentation is to summarize generated bioaccessibility data for ferro-chromium and ferro-silicon-chromium alloys in particulate form when exposed to different synthetic biological media. The selection of test media aims to mimic relevant human exposures, as far as practical, with the focus on inhalation and subsequent ingestion of inhaled particles. The generation of bioaccessibility data combined with detailed particle and material characterization, also from a surface perspective, is essential for accurate risk assessment and understanding of potential adverse effects that may be caused by ferro-chromium and ferro-silicon-chromium alloys. For comparison, a similar approach has been conducted on particles of pure iron, pure chromium and stainless steel grade AISI 316L. Generated data is used within the framework of risk assessment on ferro-chromium and ferro-siliconchromium alloys conducted by the Finnish Institute of Occupational Health, Helsinki, Finland.
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