Composition and structure of cell wall ulvans recovered from Ulva spp. along the Swedish west coast

The cell wall polysaccharide ulvan was isolated from two species of the seaweed Ulva collected along the Swedish west coast. Acidic extraction was benchmarked against hot water extraction with enzymatic purification and against commercial ulvan. Extracted ulvan contained 11–18 % g/g of ash, some protein (up to 1.3 % g N/g) but minimal colored impurities. The ulvans had high molecular weights (660,000–760,000 g/mol) and were composed of 77–79 % g/g carbohydrates, mainly rhamnose, xylose, glucose, glucuronic acid, and iduronic acid. The extraction protocol and the ulvan source strongly impact the molecular weight and the chemical composition. Acidic extraction caused almost complete desulfation of the isolated ulvan while the other method preserved a significant degree of SO3 substituents. Elemental analysis of ash remaining after thermal degradation showed presence of common mineral elements such as Na, Ca, Mg, Al, and K, but none of the heavy metals Pb, Hg, or As

Early cytokinin response proteins and phosphoproteins of Arabidopsis thaliana identified by proteome and phosphoproteome profiling

Cytokinins are plant hormones involved in regulation of diverse developmental and physiological processes in plants whose molecular mechanisms of action are being intensely researched. However, most rapid responses to cytokinin signals at the proteomic and phosphoproteomic levels are unknown. Early cytokinin responses were investigated through proteome-wide expression profiling based on image and mass spectrometric analysis of two-dimensionally separated proteins and phosphoproteins. The effects of 15 min treatments of 7-day-old Arabidopsis thaliana seedlings with four main cytokinins representing hydroxyisopentenyl, isopentenyl, aromatic, and urea-derived type cytokinins were compared to help elucidate their common and specific function(s) in regulating plant development. In proteome and phosphoproteome maps, significant differences were reproducibly observed for 53 and 31 protein spots, respectively. In these spots, 96 proteins were identified by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS), providing a snapshot of early links in cytokinin-regulated signalling circuits and cellular processes, including light signalling and photosynthesis, nitrogen metabolism, the CLAVATA pathway, and protein and gene expression regulation, in accordance with previously described cytokinin functions. Furthermore, they indicate novel links between temperature and cytokinin signalling, and an involvement of calcium ions in cytokinin signalling. Most of the differentially regulated proteins and phosphoproteins are located in chloroplasts, suggesting an as yet uncharacterized direct signalling chain responsible for cytokinin action in chloroplasts. Finally, first insights into the degree of specificity of cytokinin receptors on phosphoproteomic effects were obtained from analyses of cytokinin action in a set of cytokinin receptor double mutants

Lignin-carbohydrate complexes: Model compounds synthesis

In lignocellulose there is a recalcitrant interaction by covalent and non-covalent bonds called the lignin-carbohydrate complex. This interaction has been the subject of studies trying to unveil its chemical structure, to understand the mechanims involved in its formation and to determine its influence on practical applications such as the process of turning biomass into ethanol. Through the synthesis of model compounds we aim to further advance the scientific understanding of the lignin-carbohydrate complex. After a general introduction this thesis presents the scale-up and synthesis of ligin model compounds. A 5 L batch reactor was used to perform synthesis on 0.5 kg scale. Reaction conditions were optimized on lab scale before scale-up to ensure a safe and efficient reaction. Lignin model compounds were synthesized to enable the following synthesis of benzyl ether and benzyl ester model compounds that mimic the naturally occurring lignincarbohydrate covalent bond. The benzyl ethers and esters were synthesized via a quinone methide route to afford the products as mixtures of diastereomers. The model compounds were then used as substrates to investigate the hydrolytic properties of a hypothesized lignin-carbohydrate complex cleaving enzyme StGE2. The stability and solubility was also investigated in the optimization process of the enzymatic assay

Lignin-carbohydrate complexes: Model compounds synthesis

In lignocellulose there is a recalcitrant interaction by covalent and non-covalent bonds called the lignin-carbohydrate complex. This interaction has been the subject of studies trying to unveil its chemical structure, to understand the mechanims involved in its formation and to determine its influence on practical applications such as the process of turning biomass into ethanol. Through the synthesis of model compounds we aim to further advance the scientific understanding of the lignin-carbohydrate complex. After a general introduction this thesis presents the scale-up and synthesis of ligin model compounds. A 5 L batch reactor was used to perform synthesis on 0.5 kg scale. Reaction conditions were optimized on lab scale before scale-up to ensure a safe and efficient reaction. Lignin model compounds were synthesized to enable the following synthesis of benzyl ether and benzyl ester model compounds that mimic the naturally occurring lignincarbohydrate covalent bond. The benzyl ethers and esters were synthesized via a quinone methide route to afford the products as mixtures of diastereomers. The model compounds were then used as substrates to investigate the hydrolytic properties of a hypothesized lignin-carbohydrate complex cleaving enzyme StGE2. The stability and solubility was also investigated in the optimization process of the enzymatic assay

Instruktioner på film i stället för skriftliga instruktioner före en kemilaboration

Lärare möts av en digital framgångsvåg som går genom samhället. Nya digitala verktyg kommer lärare till godo i en ökande takt. Regeringen tog beslutet 2017 att införa digitaliseringsstrategin och Sverige ska bli bäst i världen på digitalisering. Regeringen betonar ändamålsenliga kompetenser för lärare.Syftet med studien är att öka kunskap om digitala verktyg. Studien inriktar sig på filminstruktioner innan en kemilaboration för elever i kemi 1 på gymnasiet. I studien ingår elevernas möte med filmen i undervisningen och fokusgruppsintervjuer med eleverna efter att skriftliga instruktioner hade bytts ut mot filminstruktioner före laborationen. Med filmen får eleverna förberedelser digitalt från hemmet och mer tid för praktiskt lärande på lektionstid.Resultatet är elevernas upplevelser av filmen som didaktiskt verktyg. Slutsatsen för studien ger ökade kunskaper om filmens didaktiska fördelar som rekonstruktion av en kemilaboration. Digitalisering med film har didaktiska fördelar enligt studien, eleverna aktiveras i sitt lärande och intresset för kemilaborationen ökar

Electricity dependency and CO2 emissions from heating in the Swedish building sector-Current trends in conflict with governmental policy?

Coal-condensing power is marginal production in the deregulated Nordic power market and an increase in electricity consumption will therefore result in increased CO2 emissions. One goal of the Swedish energy policy is to reduce the amount of electricity used for heating in the building sector. This paper investigates the potential for reduction in electricity dependency and CO2 emissions from heating, taking the energy infrastructure into account, here defined as the capital stock of the buildings and heating systems together with geographical variations in heat intensity. In order to include the energy infrastructure in the analysis the study is made on a regional level (Southern Sweden) applying a comprehensive database describing the energy infrastructure of the region. The paper compares two scenarios for converting the heating systems of the region: one employing energy savings and with the aim to phase out the oil and most of the electricity used for heating purposes and a second which illustrates the effect if the current trend in the heating market continues. Both scenarios apply commercially available technologies only. From the second scenario it is seen that the current trend-contrary to the aim of the Swedish Governmental policy-shows an increase in electricity dependency for heating, mainly due to a large diffusion of heat pumps, but also due to installations of electrical floor heating and electricity heating systems installed in newly constructed one- and two-dwelling buildings. However, the options proposed in first scenario show that it is possible to reach significant reductions in the electricity dependency due to heating and in corresponding CO2 emissions. An analysis of the age structure of the heating systems shows that the transformation of the heating system is not completed until the year 2025, if new investments for replacement of heating systems are made only provided they have reached their economical life time, and only applying heating technologies which at present are known to be economically competitive. It can be concluded that future policies on transforming the energy system should be based on an analysis that takes the entire energy infrastructure (in this case of heating system) into account (e.g. not directed towards single technologies). More specifically for the region studied, which is considered representative for Sweden as a whole, policies should aim at installing heat pumps to replace electricity heating only in regions with low heat density where district heating is not competitive, in contrary to the present situation where heat pumps replace all types of heating systems

Primary energy use for heating in the Swedish building sector - Current trends and proposed target

One goal of the Swedish energy policy is to reduce the amount of electricity used for heating in the building sector. This means to reduce the primary energy used for heating which in this paper is analyzed in the context of various heating technologies and CO2 emissions. The analysis is applied to a region in Sweden (southern Sweden) for which detailed information on the energy infrastructure (the capital stock of the buildings and heating systems together with geographical variations in heat intensity) is available from a previous work [Johansson, P., Nylander, A., Johnsson, F., 2005. Electricity dependency and CO2 emissions from heating in the Swedish building sector-current trends in conflict with governmental policy? Energy policy] and which is large enough to be assumed representative for Sweden as a whole. The detailed mapping of the energy infrastructure allows a good estimate on the rate at which the energy system can be expected to be replaced with respect to economical lifetime of the capital stock (the year 2025 in this case). Two scenarios are investigated; a: target scenario for which energy savings are employed (e.g. improving climate shell in buildings) and oil and most of the electricity used for heating purposes are phased out and a second for which the current trend in the heating market continues. In the target scenario it is shown that although only applying commercially competitive heating technologies, it is possible to achieve a 47% reduction in primary energy use for heating with a 34% decrease in heat demand together with significant reduction in CO2 emissions. However, the scenario which continues the current trends on the heating market instead yields an increase (of about 10%) in primary energy use (reduction in conversion efficiency) of the heating system of the region over the period studied, in spite of a slight decrease in heat demand (9%, mainly due to energy efficiency measures) as well as in CO2 emissions. In light of the recently proposed introduction of energy performance certification of buildings in Sweden (and in EU), it can be concluded that such a certification system must take into account the primary energy use and local conditions. A politically acceptable way to do so would be to propose municipalities to develop "best strategies" on development of the heating market for various house types and districts within the municipality which can then be included as recommendations in the energy performance certification of the buildings. (c) 2006 Elsevier Ltd. All rights reserved