Skin permeation and metabolism of di(2-ethylhexyl) phthalate (DEHP).

Phthalates are suspected to be endocrine disruptors. Di(2-ethylhexyl) phthalate (DEHP) is assumed to have low dermal absorption; however, previous in vitro skin permeation studies have shown large permeation differences. Our aims were to determine DEHP permeation parameters and assess extent of skin DEHP metabolism among workers highly exposed to these lipophilic, low volatile substances. Surgically removed skin from patients undergoing abdominoplasty was immediately dermatomed (800 μm) and mounted on flow-through diffusion cells (1.77 cm(2)) operating at 32°C with cell culture media (aqueous solution) as the reservoir liquid. The cells were dosed either with neat DEHP or emulsified in aqueous solution (166 μg/ml). Samples were analysed by HPLC-MS/MS. DEHP permeated human viable skin only as the metabolite MEHP (100%) after 8h of exposure. Human skin was able to further oxidize MEHP to 5-oxo-MEHP. Neat DEHP applied to the skin hardly permeated skin while the aqueous solution readily permeated skin measured in both cases as concentration of MEHP in the receptor liquid. DEHP pass through human skin, detected as MEHP only when emulsified in aqueous solution, and to a far lesser degree when applied neat to the skin. Using results from older in vitro skin permeation studies with non-viable skin may underestimate skin exposures. Our results are in overall agreement with newer phthalate skin permeation studies

Human skin in vitro permeation of bentazon and isoproturon formulations with or without protective clothing suit

Skin exposures to chemicals may lead, through percutaneous permeation, to a significant increase in systemic circulation. Skin is the primary route of entry during some occupational activities, especially in agriculture. To reduce skin exposures, the use of personal protective equipment (PPE) is recommended. PPE efficiency is characterized as the time until products permeate through material (lag time, Tlag). Both skin and PPE permeations are assessed using similar in vitro methods; the diffusion cell system. Flow-through diffusion cells were used in this study to assess the permeation of two herbicides, bentazon and isoproturon, as well as four related commercial formulations (Basagran(®), Basamais(®), Arelon(®) and Matara(®)). Permeation was measured through fresh excised human skin, protective clothing suits (suits) (Microchem(®) 3000, AgriSafe Pro(®), Proshield(®) and Microgard(®) 2000 Plus Green), and a combination of skin and suits. Both herbicides, tested by itself or as an active ingredient in formulations, permeated readily through human skin and tested suits (Tlag < 2 h). High permeation coefficients were obtained regardless of formulations or tested membranes, except for Microchem(®) 3000. Short Tlag, were observed even when skin was covered with suits, except for Microchem(®) 3000. Kp values tended to decrease when suits covered the skin (except when Arelon(®) was applied to skin covered with AgriSafe Pro and Microgard(®) 2000), suggesting that Tlag alone is insufficient in characterizing suits. To better estimate human skin permeations, in vitro experiments should not only use human skin but also consider the intended use of the suit, i.e., the active ingredient concentrations and type of formulations, which significantly affect skin permeation

Ex vivo human skin permeation of methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI).

Methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) are biocides used in many types of products such as cosmetics, paints, and cleaning agents. Skin contact is often encountered when using these products. Although MCI and MI are strong allergens and cause skin irritation, no scientific skin permeation study has been reported except for some unpublished data. Therefore, this study assessed the permeation of MCI and MI both separately and as a mixture through freshly dermatomed human skin (800 µm) in a flow-through diffusion cell system. Different concentrations of aqueous standards (1.5/1, 70/50, 150/35, and 750/175 µg/mL of MCI/MI) and various commercial products were assessed after 15-20 h of exposure. In parallel, the dose-dependent irritant effects of MCI/MI and MI were estimated by histology following 6- or 24-h exposure. Overall results show that MI in formulations or in aqueous standard solutions quickly permeated the skin with time lags less than 15 min while MCI was much slower (>3.5 h). MCI in formulations had permeation rates up to five times greater than that for MI in the same product, and in two tested creams were not found to permeate skin. Some signs of irritation were observed by histology; especially at the highest MCI/MI concentrations (750/250 µg/mL) in aqueous solutions. This confirms that MCI reacts readily with skin and may induce local irritation. The MCI and MI permeations are also greatly influenced by the topical vehicle. It is, therefore, more relevant to test exposures to formulations than aqueous standard solutions

Polycyclic aromatic hydrocarbons (PAHs) skin permeation rates change with simultaneous exposures to solar ultraviolet radiation (UV-S).

Road construction workers are simultaneously exposed to two carcinogens; solar ultraviolet (UV-S) radiation and polycyclic aromatic hydrocarbons (PAHs) in bitumen emissions. The combined exposure may lead to photogenotoxicity and enhanced PAH skin permeation rates. Skin permeation rates (J) for selected PAHs in a mixture (PAH-mix) or in bitumen fume condensate (BFC) with and without UV-S co-exposures were measured with in vitro flow-through diffusion cells mounted with human viable skin and results compared. Possible biomarkers were explored. Js were greater with UV-S for naphthalene, anthracene, and pyrene in BFC (0.08-0.1 ng/cm javax.xml.bind.JAXBElement@5490394f /h) compared to without (0.02-0.26 ng/cm javax.xml.bind.JAXBElement@2ff08242 /h). This was true for anthracene, pyrene, and chrysene in the PAH-mix. Naphthalene and benzo(a)pyrene (BaP) in the PAH-mix had greater Js without (0.97-13.01 ng/cm javax.xml.bind.JAXBElement@4d9aaf01 /h) compared to with UV-S (0.40-6.35 ng/cm javax.xml.bind.JAXBElement@6fa62fdf /h). Time until permeation (T javax.xml.bind.JAXBElement@3a293925 ) in the PAH-mix were generally shorter compared to the BFC, and they ranged from 1 to 13 h. The vehicle matrix could potentially be the reason for this discrepancy as BFC contains additional not identified substances. Qualitative interpretation of p53 suggested a dose-response with UV-S, and somewhat with the co-exposures. MMP1, p65 and cKIT were not exploitable. Although not statistically different, PAHs permeate human viable skin faster with simultaneous exposures to UV

Cosmic History and a Candidate Parent Asteroid for the Quasicrystal-bearing Meteorite Khatyrka

The unique CV-type meteorite Khatyrka is the only natural sample in which "quasicrystals" and associated crystalline Cu,Al-alloys, including khatyrkite and cupalite, have been found. They are suspected to have formed in the early Solar System. To better understand the origin of these exotic phases, and the relationship of Khatyrka to other CV chondrites, we have measured He and Ne in six individual, ~40-{\mu}m-sized olivine grains from Khatyrka. We find a cosmic-ray exposure age of about 2-4 Ma (if the meteoroid was <3 m in diameter, more if it was larger). The U,Th-He ages of the olivine grains suggest that Khatyrka experienced a relatively recent (<600 Ma) shock event, which created pressure and temperature conditions sufficient to form both the quasicrystals and the high-pressure phases found in the meteorite. We propose that the parent body of Khatyrka is the large K-type asteroid 89 Julia, based on its peculiar, but matching reflectance spectrum, evidence for an impact/shock event within the last few 100 Ma (which formed the Julia family), and its location close to strong orbital resonances, so that the Khatyrka meteoroid could plausibly have reached Earth within its rather short cosmic-ray exposure age.Comment: Submitted to Earth and Planetary Science Letter

Human skin in vitro permeation of bentazon and isoproturon formulations with or without protective clothing suit

Skin exposures to chemicals may lead, through percutaneous permeation, to a significant increase in systemic circulation. Skin is the primary route of entry during some occupational activities, especially in agriculture. To reduce skin exposures, the use of personal protective equipment (PPE) is recommended. PPE efficiency is characterized as the time until products permeate through material (lag time, Tlag). Both skin and PPE permeations are assessed using similar in vitro methods; the diffusion cell system. Flow-through diffusion cells were used in this study to assess the permeation of two herbicides, bentazon and isoproturon, as well as four related commercial formulations (Basagran®, Basamais®, Arelon® and Matara®). Permeation was measured through fresh excised human skin, protective clothing suits (suits) (Microchem® 3000, AgriSafe Pro®, Proshield® and Microgard® 2000 Plus Green), and a combination of skin and suits. Both herbicides, tested by itself or as an active ingredient in formulations, permeated readily through human skin and tested suits (Tlag<2h). High permeation coefficients were obtained regardless of formulations or tested membranes, except for Microchem® 3000. Short Tlag, were observed even when skin was covered with suits, except for Microchem® 3000. Kp values tended to decrease when suits covered the skin (except when Arelon® was applied to skin covered with AgriSafe Pro and Microgard® 2000), suggesting that Tlag alone is insufficient in characterizing suits. To better estimate human skin permeations, in vitro experiments should not only use human skin but also consider the intended use of the suit, i.e., the active ingredient concentrations and type of formulations, which significantly affect skin permeation

Codivergence of Mycoviruses with Their Hosts

BACKGROUND: The associations between pathogens and their hosts are complex and can result from any combination of evolutionary events such as codivergence, switching, and duplication of the pathogen. Mycoviruses are RNA viruses which infect fungi and for which natural vectors are so far unknown. Thus, lateral transfer might be improbable and codivergence their dominant mode of evolution. Accordingly, mycoviruses are a suitable target for statistical tests of virus-host codivergence, but inference of mycovirus phylogenies might be difficult because of low sequence similarity even within families. METHODOLOGY: We analyzed here the evolutionary dynamics of all mycovirus families by comparing virus and host phylogenies. Additionally, we assessed the sensitivity of the co-phylogenetic tests to the settings for inferring virus trees from their genome sequences and approximate, taxonomy-based host trees. CONCLUSIONS: While sequence alignment filtering modes affected branch support, the overall results of the co-phylogenetic tests were significantly influenced only by the number of viruses sampled per family. The trees of the two largest families, Partitiviridae and Totiviridae, were significantly more similar to those of their hosts than expected by chance, and most individual host-virus links had a significant positive impact on the global fit, indicating that codivergence is the dominant mode of virus diversification. However, in this regard mycoviruses did not differ from closely related viruses sampled from non-fungus hosts. The remaining virus families were either dominated by other evolutionary modes or lacked an apparent overall pattern. As this negative result might be caused by insufficient taxon sampling, the most parsimonious hypothesis still is that host-parasite evolution is basically the same in all mycovirus families. This is the first study of mycovirus-host codivergence, and the results shed light not only on how mycovirus biology affects their co-phylogenetic relationships, but also on their presumable host range itself

System perturbations in low voltage grids due to decentralized photovoltaic systems

Die Netzintegration einer großen Anzahl von Photovoltaikanlagen in bestehende Niederspannungsnetze führt zu neuen Herausforderungen bezüglich der Spannungsqualität. Diese Arbeit untersucht und modelliert durch photovoltaische Einspeisung hervorgerufene Oberschwingungen und Flicker und deren Netzrückwirkungen. Weiterhin wird ein Simulationsmodell entwickelt mit dem unbeabsichtigte Blindleistungseinspeisungen – von Wechselrichtern mit dem angegebenen Leistungsfaktor Eins - charakterisiert und somit die realen Netzparameter mit einer höheren Genauigkeit reproduziert werden. Diese Arbeit liefert somit einen Beitrag für eine effiziente und zuverlässige Netzintegration von Photovoltaikanlagen.The grid integration of a huge number of photovoltaic systems in existing low voltage grids leads to new challenges in ensuring the required power quality. The objective of this thesis is the analysis and modelling of the perturbations harmonics and flicker coming from photovoltaic systems. Furthermore, a simulation model to characterize unintended reactive power flows of photovoltaic inverter systems - including a stated power factor of one - and to reproduce the real grid parameters with a higher accuracy is introduced. Consequently, this thesis makes a contribution for an effective and reliable grid integration of photovoltaic systems