| 1. |
- Destouni, Georgia, et al.
(författare)
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Hydro-Biogeochemical and Environmental-Management Functions of Wetland Networks in Landscapes
- 2012
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Ingår i: 9th INTECOL International Wetlands Conference, Wetlands in a Complex World. ; , s. 915-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A main application goal of ecohydrological science is to amplify opportunities of achieving water quality improvements, biodiversity enhancements and sustainable development, by improved understanding and use of ecosystem properties as a management tool. This paper draws on and synthesizes main result implications for the function and possible enhanced use of wetland networks in the landscape as such a tool, from a series of hydro-biogeochemical and environmental economics studies of nutrient/pollutant loading and abatement in different Swedish hydrological catchments. Results show large potential of wetland networks to reduce the cost of abating nutrient and metal loads within and from hydrological catchments, and emphasize some main research questions for further investigations of actual possibilities to realize this potential. The questions regard in particular the ability of wetland networks to extend the travel times and reduce the uncertainty of hydrological nutrient/pollutant transport through catchments.The paper further presents and discusses some main joint conclusions of the participants in a recently held International Workshop on Ecohydrology and Integrated Water Resource Management (1) at the Navarino Environmental Observatory in Messinia, Greece (2), regarding essential goals for collaborative international efforts in wetland network research. The goals include to investigate on different spatiotemporal scales and in different world regions: a) the dynamics of natural and managed wetland networks across a gradient of different climate, human disturbance, energy and organization conditions; b) the reciprocal interactions between wetland networks and associated hydrological catchments; c) how climate change and different human activities in the wetland network catchments influence these interactions (in b) and generally the ecohydrology of individual wetlands and the whole wetland networks; and d) the ecosystem services provided by networks of wetlands.
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| 2. |
- Åstrand, Håkan, et al.
(författare)
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In vivo estimation of the contribution of elastin and collagen on the mechanical properties in the abdominal aorta of man : effect of age and gender
- 2011
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Ingår i: Journal of applied physiology. - : AMER PHYSIOLOGICAL SOC. - 8750-7587 .- 1522-1601. ; 110:1, s. 8750-8757
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical properties of the aorta affect cardiac function and are related to cardiovascular morbidity/mortality. This study was designed to evaluate the isotropic (mainly elastin, elastiniso) and anisotropic (mainly collagen, collagenani) material parameters within the human aorta in vivo. Thirty healthy men and women in three different age categories (23–30, 41–54, and 67–72 yr) were included. A novel mechanical model was used to identify the mechanical properties and the strain field with aid of simultaneously recorded pressure and radius in the abdominal aorta. The magnitudes of the material parameters relating to both the stiffness of elastiniso and collagenani were in agreement with earlier in vitro studies. The load-bearing fraction attributed to collagenani oscillated from 10 to 30% between diastolic and systolic pressures during the cardiac cycle. With age, stiffness of elastiniso increased in men, despite the decrease in elastin content that has been found due to elastolysis. Furthermore, an increase in stiffness of collagenani at high physiological pressure was found. This might be due to increased glycation, as well as changed isoforms of collagen in the aortic wall with age. A marked sex difference was observed, with a much less age-related effect, both on elastiniso and collagenani stiffness in women. Possible factors of importance could be the effect of sex hormones, as well as differing collagen isoforms, between the sexes.
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| 3. |
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| 4. |
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Bergtagen
- 2020. - 200
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Samlingsverk (redaktörskap) (populärvet., debatt m.m.)
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| 5. |
- Delsing, Jerker, et al.
(författare)
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Low-pressure gap discharge ultrasonic gas flowmeter
- 2010
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Ingår i: The 15th International Flow Measurement Conference. ; , s. 259-266
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Konferensbidrag (refereegranskat)abstract
- Low-pressure gas measurements are of increasing interest in the process industry for both control purposes and emission measurements. Industrial measurement environments include some very challenging components, such as:- Dust, particles, vapor, water droplets, etc.- Temperatures up to 1200°C- Pipe diameters of 1 to 10 mUltrasound flow measurement techniques have many advantages for such industrial measurement problems. Currently, a major problem is the lack of transducer technology that is sufficiently robust to operate in the presence of the above given industrial components. For the purpose of producing more robust technology, a gap discharge sound transmitter has been developed [1, 2]. Theoretical and experimental studies of the gap discharge transmitter indicate that flow measurement performances in the range of 1-2% of the actual flow is achievable [3]. Based on this gap discharge transmitter, an experimental ultrasound gas flowmeter was designed. The design features a gap discharge transmitter and piezo-based receivers. The design was tested in a real industrial environment. The test environment included heavy dust and water vapor in an exhaust pipe at a pelletization plant at LKAB, Kiruna, Sweden. The pipe diameter is 3 m, the pressure is ambient, and the gas flow speed is in the range of 5-20 m/s. The flow conditions were highly turbulent, using a straight pipe length ten times the pipe diameter in front of the experimental flowmeter. This paper presents the experimental gap discharge ultrasonic flowmeter design, the experimental setup and some measurement data. These data indicate that the gap discharge transmitter is feasible for operation in an industrial environment. Further preliminary flow measurement data demonstrate the feasibility of using a gap discharge transmitter as the sound-emitting source in an ultrasonic gas flowmeter.
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| 6. |
- Ekebergh, Andreas, 1984, et al.
(författare)
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Oxidative Coupling as a Biomimetic Approach to the Synthesis of Scytonemin
- 2011
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Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7052 .- 1523-7060. ; 13:16, s. 4458-4461
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Tidskriftsartikel (refereegranskat)abstract
- The first total synthesis of the dimeric alkaloid pigment scytonemin is described. The key transformations In Its synthesis from 3-indole acetic acid are a Heck carbocyclization and a Suzuki-Miyaura cross-coupling, orchestrated In a stereospecific tandem fashion, followed by a biosynthetically inspired oxidative dimerization. The tandem sequence generates a tetracyclic (E)-3-(arylidene)-3,4-dihydrocyclopenta[b]indol-2(1H)-one that is subsequently dimerized into the unique homodimeric core structure of scytonemin.
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| 7. |
- Fahlman, Johan, et al.
(författare)
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Using laboratory incubations to predict the fate of pharmaceuticals in aquatic ecosystems
- 2018
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Ingår i: Environmental Chemistry. - : CSIRO Publishing. - 1448-2517 .- 1449-8979. ; 15:8, s. 463-471
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Tidskriftsartikel (refereegranskat)abstract
- Environmental contextEnvironmental persistence of excreted pharmaceuticals in aquatic ecosystems is usually predicted using small-scale laboratory experiments assumed to simulate natural conditions. We studied five pharmaceuticals comparing their removal rates from water under laboratory conditions and under natural environmental conditions existing in a large pond. We found that the laboratory conditions did not fully capture the complexity within the pond, which led to different removal rates in the two systems. AbstractEnvironmental persistence is a key property when evaluating risks with excreted pharmaceuticals in aquatic ecosystems. Such persistence is typically predicted using small-scale laboratory incubations, but the variation in aquatic environments and scarcity of field studies to verify laboratory-based persistence estimates create uncertainties around the predictive power of these incubations. In this study we: (1) assess the persistence of five pharmaceuticals (diclofenac, diphenhydramine, hydroxyzine, trimethoprim and oxazepam) in laboratory experiments under different environmental conditions; and (2) use a three-month-long field study in an aquatic ecosystem to verify the laboratory-based persistence estimates. In our laboratory assays, we found that water temperature (TEMP), concentrations of organic solutes (TOC), presence of sediment (SED), and solar radiation (SOL) individually affected dissipation rates. Moreover, we identified rarely studied interaction effects between the treatments (i.e. SOLxSED and TEMPxSOL), which affected the persistence of the studied drugs. Half-lives obtained from the laboratory assays largely explained the dissipation rates during the first week of the field study. However, none of the applied models could accurately predict the long-term dissipation rates (month time-scale) from the water column. For example, the studied antibioticum (trimethoprim) and the anti-anxiety drug (oxazepam) remained at detectable levels in the aquatic environment long after (similar to 150 days) our laboratory based models predicted complete dissipation. We conclude that small-scale laboratory incubations seem sufficient to approximate the short-term (i.e. within a week) dissipation rate of drugs in aquatic ecosystems. However, this simplistic approach does not capture interacting environmental processes that preserve a fraction of the dissolved pharmaceuticals for months in natural water bodies.
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| 8. |
- Karlsson, Erik, 1982-
(författare)
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Catalysts for Oxygen Production and Utilization : Closing the Oxygen Cycle: From Biomimetic Oxidation to Artificial Photosynthesis
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the development and study of catalysts for redox reactions, which either utilize oxygen or hydrogen peroxide for the purpose of selectively oxidizing organic substrates, or produce oxygen as the necessary byproduct in the production of hydrogen by artificial photosynthesis.The first chapter gives a general introduction about the use of environmentally friendly oxidants in the field of organic synthesis, and about the field of artificial photosynthesis. The second chapter describes a computational study of the mechanism of palladium-catalyzed oxidative carbohydroxylation of allene-substituted conjugated dienes. The proposed mechanism, which was supported by DFT calculations, involves an unusual water attack on a (π-allyl)palladium complex. The third chapter describes a computational study of the oxidation of unfunctionalized hydrocarbons, ethers and alcohols with hydrogen peroxide, catalyzed by methyltrioxorhenium (MTO). The mechanism was found to proceed via rate-limiting hydride abstraction followed by hydroxide transfer in a single concerted, but highly asynchronous, step as shown by intrinsic reaction coordinate (IRC) scans. The fourth chapter describes the use of a new hybrid (hydroquinone-Schiff base)cobalt catalyst as electron transfer mediator (ETM) in the palladium-catalyzed aerobic carbocyclization of enallenes. Covalently linking the two ETMs gave a fivefold rate increase compared to the use of separate components. The fifth chapter describes an improved synthetic route to the (hydroquinone-Schiff base)cobalt catalysts. Preparation of the key intermediate 5-(2,5-hydroxyphenyl)salicylaldehyde was improved by optimization of the key Suzuki coupling and change of protecting groups from methyl ethers to easily cleaved THP groups. The catalysts could thus be prepared in good overall yield from inexpensive starting materials.Finally, the sixth chapter describes the preparation and study of two catalysts for water oxidation, both based on ligands containing imidazole groups, analogous to the histidine residues present in the oxygen evolving complex (OEC) and in many other metalloenzymes. The first, ruthenium-based, catalyst was found to catalyze highly efficient water oxidation induced by visible light. The second catalyst is, to the best of our knowledge, the first homogeneous manganese complex to catalyze light-driven water oxidation.
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| 9. |
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| 10. |
- Karlsson, Isabella, 1980, et al.
(författare)
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Clinical and experimental studies of octocrylene's allergenic potency
- 2011
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Ingår i: Contact Dermatitis. - : Wiley. - 1600-0536 .- 0105-1873. ; 64:6, s. 343-52
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Tidskriftsartikel (refereegranskat)abstract
- Background. Reports of positive patch test and photopatch test reactions to the chemical ultraviolet filter octocrylene have increased during the last decade. Little is known about the reason for octocrylene's allergenic activity. Objectives. To present and discuss the results of patch tests and photopatch tests with octocrylene, and to investigate the possible cause of its allergenic properties. Methods. Results of patch tests and photopatch tests with octocrylene in patients with adverse skin reactions to sunscreen products and/or ketoprofen were collected. The allergenic potency of octocrylene was investigated in the murine local lymph node assay (LLNA). Chemical reactivity assays were used to mimic octocrylene's interaction with biomolecules. Results. We report 23 cases of positive test reactions to octocrylene (5 patch test and 18 photopatch). Notably, many of these patients also had positive photopatch test reactions to ketoprofen and benzophenone-3. Octocrylene was shown to be a moderate sensitizer in the LLNA, and it reacted with amines such as lysine, but not with thiols such as cysteine. Conclusions. The clinical studies show that octocrylene is both a photocontact allergen and a contact allergen. Octocrylene's ability to cause contact allergy is probably attributable to its reactivity towards lysine. To be able to understand why octocrylene causes photocontact allergy, further studies are needed.
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