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- Bermudez, Rafael, et al.
(author)
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Long-Term Conditioning to Elevated pCO(2) and Warming Influences the Fatty and Amino Acid Composition of the Diatom Cylindrotheca fusiformis
- 2015
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:5
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Journal article (peer-reviewed)abstract
- The unabated rise in anthropogenic CO2 emissions is predicted to strongly influence the ocean's environment, increasing the mean sea-surface temperature by 4 degrees C and causing a pH decline of 0.3 units by the year 2100. These changes are likely to affect the nutritional value of marine food sources since temperature and CO2 can influence the fatty (FA) and amino acid (AA) composition of marine primary producers. Here, essential amino (EA) and polyunsaturated fatty (PUFA) acids are of particular importance due to their nutritional value to higher trophic levels. In order to determine the interactive effects of CO2 and temperature on the nutritional quality of a primary producer, we analyzed the relative PUFA and EA composition of the diatom Cylindrotheca fusiformis cultured under a factorial matrix of 2 temperatures (14 and 19 degrees C) and 3 partial pressures of CO2 (180, 380, 750 mu atm) for >250 generations. Our results show a decay of similar to 3% and similar to 6% in PUFA and EA content in algae kept at a pCO(2) of 750 mu atm (high) compared to the 380 mu atm (intermediate) CO2 treatments at 14 degrees C. Cultures kept at 19 degrees C displayed a similar to 3% lower PUFA content under high compared to intermediate pCO(2), while EA did not show differences between treatments. Algae grown at a pCO(2) of 180 mu atm (low) had a lower PUFA and AA content in relation to those at intermediate and high CO2 levels at 14 degrees C, but there were no differences in EA at 19 degrees C for any CO2 treatment. This study is the first to report adverse effects of warming and acidification on the EA of a primary producer, and corroborates previous observations of negative effects of these stressors on PUFA. Considering that only similar to 20% of essential biomolecules such as PUFA (and possibly EA) are incorporated into new biomass at the next trophic level, the potential impacts of adverse effects of ocean warming and acidification at the base of the food web may be amplified towards higher trophic levels, which rely on them as source of essential biomolecules.
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- Larsson, Anna-Lena, 1971-
(author)
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All-Thin-Film Electrochromic Devices for Optical and Thermal Modulation
- 2004
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Doctoral thesis (other academic/artistic)abstract
- The optical properties of electrochromic materials can be changed by application of an electrical voltage. The conventional electrochromic device consists of several thin films of electrochromic materials and layers for electron- and ion conduction. The ion conductor in devices intended for applications using visible light is often a polymer electrolyte that is used to laminate two half-cells together. The miniaturization of satellites has led to reduced mass and volume available for systems to handle temperature variations onboard. The satellite will be submitted to large variations in the radiating environment in an earth bound orbit. An electrochromic device could provide adaptable radiation exchange due to its variable infrared optical properties. The polymer electrolyte is not a desirable component in the space environment, but it can be replaced by an inorganic thin film so that an all-thin-film (ATF) device is obtained. This thesis investigates the optical properties of amorphous and crystalline WO3, as well as the performance of ATF devices with sputtered ZrO2 as the ion conductor. The infrared reflectance for Li-intercalated WO3 has been measured in the wavelength range 2-50 mm. The near infrared absorption for low intercalation levels showed good agreement with large polaron theory. The infrared reflectance increased with higher intercalation levels and exhibited a free-electron behaviour. The infrared reflectance of a laminated device with polymer electrolyte was measured, and the calculated emittance varied between 0.56 and 0.65. The ATF device consisted of thin films of WO3, ZrO2 and NiVxOyHz, as well as evaporated Al top contacts. The substrates were commercial ITO on glass. The emittance for different device designs was calculated from reflectance measurements, and could be varied between 0.33 and 0.59. This makes them strong contenders to other contemporary emittance modulating devices.
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