71 research outputs found

    Effects of geographical location on potentially valuable components in Ulva intestinalis sampled along the Swedish coast

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    Macroalgal biomass has the potential to become an important source of chemicals and commodities in a future biorefinery. Currently, production of macroalgal biomass is expensive and the content of high-value compounds is often low. Therefore, in this study the biochemical composition of\ua0Ulva intestinalis\ua0along the Swedish west coast and the east coast up to Stockholm was assessed with the aim of determining how the content of potentially valuable compounds, such as rhamnose, iduronic acid and PUFAs, could be maximized by utilizing natural variation in the choice of marine cultivation site. Along the investigated coastline, the salinity dropped from 19.4‰ at high latitudes along the west coast to 5.4‰ at Stockholm. Nitrogen and phosphorus availability varied, while temperature was similar at all locations. The two major components of biomass, carbohydrates and ash, varied inversely with the highest content of ash in the west and carbohydrates in the east. In addition, total fatty acids were significantly higher in west coast samples at 3.2\ua0g 100\ua0g–1\ua0dw, with a higher proportion of mono- and polyunsaturated fatty acids. Some health-beneficial fatty acids were found, including EPA and DPA, at 10–50\ua0mg 100\ua0g–1\ua0dw, respectively. The metal content and elemental composition varied widely, probably due to the influence of specific local conditions. The P content was correlated with the phosphorus concentration in waters at the locations. In PCA analysis, the monosaccharides constituting the cell wall polysaccharide ulvan were found to vary by geographical location, with higher levels possibly associated with lower salinities. However, only glucuronic acid differed significantly between sites. These results show the considerable geographical variability in the composition of Swedish\ua0U. intestinalis\ua0and suggest that different salinities could be used to create a lipid- or carbohydrate-rich biomass

    Impedance investigation of BaCe0.85Y0.15O3-delta properties for hydrogen conductor in fuel cells

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    International audienceThe influence of the sintering conditions on the electrochemical properties of the proton conducting electrolyte BaCe0.85Y0.15O3-delta (BCY15) and Ni - based BCY15 cermet anode for application in high temperature proton conducting fuel cell are investigated by electrochemical impedance spectroscopy. The results show that at lower sintering temperatures due to the formation of parasitic Y2O3 phase an increase of both the electrolyte and electrode resistances is observed. This effect is strongly reduced by enhancement of the sintering temperature. The obtained BCY15 conductivity (sigma = 2.5x10(-2) S/cm at 700 degrees C) is comparable with that of the best proton conducting materials, while the BCY15-Ni cermet (with ASR = 2.5 Omega cm(2) at 700 degrees C) needs further optimization. The results of impedance investigations of BCY15 as proton conducting electrolyte and cermet anode have been applied in development of innovative high temperature dual membrane fuel cell

    Improving electrocoagulation floatation for harvesting microalgae

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    Electro-coagulation floatation (ECF) is a foam-floatation dewatering method that has been shown to be a highly effective, rapid, and scalable separation methodology. In this manuscript, an in-depth analysis of the gas and flocculant levels observed during the process is provided, with microbubbles observed in the 5–80μm size range at a concentration of 102–103 bubbles mL−1. Electrolysis of microalgae culture was then observed, demonstrating both effective separation using aluminium electrodes (nine microalgal species tested, 1–40μm size range, motile and non-motile, marine and freshwater), and sterilisation of culture through bleaching with inert titanium electrodes. Atomic force microscopy was used to visualise floc formation in the presence and absence of algae, showing nanoscale structures on the magnitude of 40–400nm and entrapped microalgal cells. Improvements to aid industrial biotechnology processing were investigated: protein-doping was found to improve foam stability without inducing cell lysis, and an oxalate buffer wash regime was found to dissolve the flocculant whilst producing no observable difference in the final algal lipid or pigment profiles, leaving the cells viable at the end of the process. ECF separated microalgal culture had an algal biomass loading of 13% and as such wasideal for direct down-stream processing through hydrothermal liquefaction. Highbio-crude yieldswere achieved, though this was reduced slightly on addition of the Al(OH)3 after ECF, with carbon being distributed away to the aqueous and solid residue phases. The amenability and compatibility of ECF to integration with, or replacement of, existing centrifugation and settling processes suggests this process may be of significant interest to the biotechnology industry

    Hazard of Runaway of Nitration Processes in Nitrocompounds Production

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    Hazard of runaway of nitration processes in nitrocompounds production was investigated. Temperature rise in DNT nitration mixes under near adiabatic conditions was measured, and derivative dT/dζ was computed. Heat evolution rate caused by nitration (primary reaction) and oxidation (secondary reaction) were examined by means of elaborated mathematical model. Limiting values of T and dT/dζ for safe process were determined. The second part of investigation concerns detonability of solutions of nitrocompound in sulfuric acid. The detonation failure diameter df and detonation velocity D of solutions of trinitrotoluene, dinitrotoluene, and trinitrobenzene in sulfuric acid and oleum have been measured in the wide range of concentrations at T = 90C. It was shown that the detonability of the nitrocompounds depends signifcantly on the sulfuric acid content. The minimum value of df for the mixture TNT/oleum is about 2 mm, i.e., 30 times less, than that for melted TNT, and practically equals to df of nitroglycerine

    Inductance correction in impedance study of solid oxide fuel cells

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    A procedure for evaluation and elimination of errors, caused by parasitic inductance and resistance in EIS studies of two solid oxide fuel cells (SOFC) materials: yttria stabilized zirconia (YSZ) electrolyte and lanthanum strontium manganite (LSM)/YSZ composite cathode is presented in this paper. It is shown that for these low impedance systems the parasitic inductance can affect not only the high frequencies but also the middle and low ones. The parasitic errors correction procedure increases significantly the reliability of the electrochemical impedance spectroscopy (EIS) results

    Electrochemical analysis of solid oxide electrolytes for intermediate temperature fuel cell

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    In this paper the electrochemical analysis of new materials, designed to be used as solid electrolytes for intermediate temperature fuel cells (IT-SOFC) was made. The materials are two different composites based on ceria 10YDC + (10%) 150ppm YA and 10ScDC + (10%) 150ppm YA, obtained by sol-gel method and sintered at temperature of 1500 0 C. The electrochemical investigation was performed by Electrochemical Impedance Spectroscopy technique. According of these analyses the composite 10YDC + (10%) 150ppm YA presents better conductivity than 10ScDC + (10%) 150ppm YA. These results were related with morphological investigation, realized by SEM

    New parasitoids of Saperda populnea (L.) (Col. Cerambycidae) in Bulgaria

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    Electrochemical analysis of solid oxide electrolytes for intermediate temperature fuel cell

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    In this paper the electrochemical analysis of new materials, designed to be used as solid electrolytes for intermediate temperature fuel cells (IT-SOFC) was made. The materials are two different composites based on ceria 10YDC + (10%) 150ppm YA and 10ScDC + (10%) 150ppm YA, obtained by sol-gel method and sintered at temperature of 1500 0 C. The electrochemical investigation was performed by Electrochemical Impedance Spectroscopy technique. According of these analyses the composite 10YDC + (10%) 150ppm YA presents better conductivity than 10ScDC + (10%) 150ppm YA. These results were related with morphological investigation, realized by SEM
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