Molecular investigations of atmospherically relevant interface processes: ice formation and water accommodation on ice and organic surfaces

Clouds and aerosols play important roles in the climate system by affecting on atmospheric chemistry, the radiation budget of the atmosphere, and the water cycle including the formation of precipitation. Climate models with predictive power require quantitative descriptions of aerosols and clouds, but several key processes remain to be fully understood. One important example is the formation and growth of ice particles in clouds. Organic compounds also form secondary organic aerosol and coatings on existing particles including ice nuclei and ice cloud particles, which further complicate the description of cloud processes. To improve the understanding of these processes, some fundamental investigations of atmospherically relevant interface interactions are carried out, and the results and findings are summarized and discussed in this thesis. The investigations use a newly developed environmental molecular beam (EMB) technique as the main experimental method. The principle, design and demonstration of the EMB method are described in detail. The method allows for ice surface investigations at temperatures up to 213 K, and it is employed to study gas-surface interactions under conditions relevant to the troposphere. The main findings of this thesis are related to three research themes: (1) Ice formation via deposition mode nucleation on hydrophobic and hydrophilic surfaces is characterized. The critical supersaturation required to activate nucleation on various surfaces increases rapidly with decreasing temperature below 200 K, and adsorbed organic compounds are observed to influence the nucleation, structure and growth rate of ice. (2) Water uptake by bare ice and coated ice surfaces is investigated. The accommodation and desorption kinetics for water on bare ice is quantitatively described by a precursor model. Coatings on ice have a significant impact on water uptake, and adsorption of acids commonly found in the atmosphere tends to enhance water accommodation. (3) Water interactions with surfaces on condensed organic phases and organic coatings on graphite are characterized. Bulk accommodation is inefficient on solid organic surfaces, while water uptake is efficient on liquid phases. The surface layer on condensed n-butanol is shown to change gradually from solid to liquid over a 10 K temperature span around the bulk melting temperature, with major implications for water uptake. The thesis includes the development of new experimental methods and an improved molecular-level understanding of processes at gas-solid and gas-liquid interfaces, and thereby contributes to a better description of cloud and aerosol processes in the environment

Function of the hydration layer around an antifreeze protein revealed by atomistic molecular dynamics simulations

Atomistic molecular dynamics simulations are used to investigate the mechanism by which the antifreeze protein from the spruce budworm, Choristoneura fumiferana, binds to ice. Comparison of structural and dynamic properties of the water around the three faces of the triangular prism-shaped protein in aqueous solution reveals that at low temperature the water structure is ordered and the dynamics slowed down around the ice-binding face of the protein, with a disordering effect observed around the other two faces. These results suggest a dual role for the solvation water around the protein. The preconfigured solvation shell around the ice-binding face is involved in the initial recognition and binding of the antifreeze protein to ice by lowering the barrier for binding and consolidation of the protein:ice interaction surface. Thus, the antifreeze protein can bind to the molecularly rough ice surface by becoming actively involved in the formation of its own binding site. Also, the disruption of water structure around the rest of the protein helps prevent the adsorbed protein becoming covered by further ice growth

Effect of forest bathing trips on human immune function

In Japan, a forest bathing trip, called “Shinrinyoku” in Japanese, is a short, leisurely visit to a forest; it is regarded as being similar to natural aromatherapy. This review focuses on the effects of forest bathing trips on human immune function. Beginning in 2005, adult Japanese individuals, both male and female, participated in a series of studies aimed at investigating the effect of forest bathing trips on human immune function. The subjects experienced a 3-day/2-night trip to forest areas, and blood and urine were sampled on days 2 (the first sampling during each trip) and 3 (the second sampling during each trip), and on days 7 and 30 after the trips. Natural killer (NK) activity, the numbers of NK, granulysin-, perforin-, and granzymes A/B-expressing lymphocytes in the blood, and the concentration of urinary adrenaline were measured. The same measurements were made before the trips on a normal working day as a control. The mean values of NK activity and the numbers of NK, granulysin-, perforin-, and granzymes A/B-expressing cells on forest bathing days were significantly higher than those on the control days, whereas the mean values of the concentration of urinary adrenaline on forest bathing days were significantly lower than that on the control days in both male and female subjects. The increased NK activity lasted for more than 30 days after the trip, suggesting that a forest bathing trip once a month would enable individuals to maintain a higher level of NK activity. In contrast, a visit to the city as a tourist did not increase NK activity, the numbers of NK cells, or the level of intracellular granulysin, perforin, and granzymes A/B. These findings indicate that forest bathing trips resulted in an increase in NK activity, which was mediated by increases in the number of NK cells and the levels of intracellular granulysin, perforin, and granzymes A/B

Intention and Negligence as Elements of Illegality : A Study of the 'personale Unrechtsauffassung'

textabstractBackground: Gastrointestinal endoscopy plays a crucial role in the diagnosis and management of gastrointestinal disorders. When endoscopy is indicated during pregnancy, concerns about the effects on pregnancy outcome often arise. The aim of this study was to assess whether lower gastrointestinal endoscopies (LGEs) across all three trimesters of pregnancy affects pregnancy outcomes. Methods: A systematic literature search was performed using Embase (including MEDLINE), Medline OvidSP, Cochrane Central Register of Controlled Trials, Web-of-Science, Google scholar and Pubmed. All original research articles from 1990 until May 2014 involving pregnant women who underwent LGE for any indication were included. Adverse pregnancy events like spontaneous abortion, preterm birth and fetal demise were assessed for a temporal and etiological relation with the LGE. Results: In total, 5514 references were screened by two independent reviewers. Eighty-two references met the inclusion criteria and were selected. Two retrospective, controlled studies, one uncontrolled study and 79 case reports were identified. In the three studies, birth outcomes did not differ between women undergoing LGE during pregnancy, compared to women that had an indication for LGE but in whom LGE was not performed because of pregnancy. In 79 case reports, 92 patients are described who underwent 100 LGE's during pregnancy. LGEs performed in all trimesters (n = 32, 39 and 29) were both temporally and etiologically related to 1, 3 and 2 adverse events, respectively. Conclusion: Based on the available literature, this review concludes that lower gastrointestinal endoscopy during pregnancy is of low risk for mother and child in all three trimesters of pregnancy