BakgrundFörskolans arena erbjuder stora möjligheter till naturvetenskapliga upptäckter varje dag. Genom barnens nyfikenhet kan ögonblick fångas upp och bli till rika lärandemiljöer inom området. För att nå dit krävs ett tillåtande klimat där barnen uppmuntras att utforska sin närmiljö. Pedagogens roll är en viktig faktor där produkt och process kan kopplas samman till en meningsfull helhet och på så sätt nå det syfte som verksamheten eftersträvar.SyfteJag vill studera hur förskolebarn agerar, reagerar och resonerar vid utforskandet av naturvetenskapliga experiment, specifikt inriktade på kemi. Mitt intresse riktar sig mot interaktionen och hur den yttrar sig mellan barnen, mellan barnen och det laborativa materialet samt mellan barnen och mig som deltagande observatör.MetodForskningsmetoden har inspirerats utifrån etnografisk ansats, där jag som forskare har valt att vara aktiv på fältet genom att inta rollen som deltagande observatör. Nio barn har medverkat i studien, indelade i tre grupper utifrån respektive förskoleavdelningar. Under laborationerna har jag observerat barnens aktioner och spelat in de samtal som aktiviteten genererat.ResultatResultatet visar en variation i förskolebarns sätt att agera, reagera och resonera vid utforskandet av naturvetenskapliga experiment. Detta synliggörs bland annat genom skillnaden i graden av intensitet hos varje enskilt barn. Gemensamt för alla barn tycks vara deras förmåga att helhjärtat gå in i utforskandet och på så sätt stänga ute intryck från omvärlden. Fantasi, kreativitet och nyfikenhet illustreras som i sin tur visar på hur glädjen infinner sig hos barnen vid utforskandet. / Program: Lärarutbildningen

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Oligonucleotides are synthetic strings of DNA or RNA used mostly for biochemical analysis and diagnostics. For them to be useful in these fields, a purity over 90% is most often required. However, when synthesizing these sequences, many “failures” (shorter sequences) are made in the step-wise process. The synthesized oligonucleotides need to therefore be purified. This is most often done with gel electrophoresis or liquid chromatography. These methods are, on the other hand, very time-consuming and laborious. Solid phase extraction (SPE) is a much faster purification method if optimized and it can be done with the standard cartridges as well as 96-well plates, that allow many samples to efficiently be run at the same time. With reversed phase (RP) SPE, the dimethoxytrityl (DMT) group, that is attached to the target at the final synthesis step, can be used for stronger retention to the bed sorbent and leaving only the target at the final eluting stage. The impurities without a DMT-on group, that do not adsorb to the sorbent, are washed away in earlier steps. The purpose of this study is to optimize an SPE method for purification of oligonucleotides. Two different cartridges, Clarity QSP (Phenomenex) and Glen-Pak (Glen Research) were used. The purity analysis and oligonucleotide identification were done using anion exchange - high performance liquid chromatography (AIE-HPLC) and time-of-flight mass spectrometry (TOF MS). To conclude, Clarity QSP achieved, at the most, a purity of 68.8% with the recommended SPE steps by Phenomenex. Alterations in the extraction procedure resulted in similar purity or lower. Glen-Pak reached a peak purity of 78.8% when doing a double salt wash of 5% ACN in 2 M sodium chloride and another double wash after detritylation with 1% acetonitrile. This method has to be further optimized in order to reach a purity of at least 90% to be useful in industrial settings.

<p>This thesis deals with the synthesis and characterisation of a series of dinuclear manganese complexes. Their ability to donate electrons to photo-generated ruthenium(III) has been investigated in flash photolysis experiments followed by EPR-spectroscopy. These experiment shows several consecutive one-electron transfer steps from the manganese moiety to ruthenium(III), that mimics the electron transfer from the oxygen evolving centre in photosystem II.</p><p>The redox properties of these complexes have been investigated with electro chemical methods and the structure of the complexes has been investigated with different X-ray techniques. Structural aspects and the effect of water on the redox properties have been shown.</p><p>One of the manganese complexes has been covalently linked in a triad donor-photosensitizer-acceptor (D–P–A) system. The kinetics of this triad has been investigated in detail after photo excitation with both optical and EPR spectroscopy. The formed charge separated state (D^––P–A⁺) showed an unusual long lifetime for triad based on ruthenium photosensitizers.</p><p>The thesis also includes a study of manganese-salen epoxidation reactions that we believe can give an insight in the oxygen transfer mechanism in the water oxidising complex in photosystem II.</p>

<p>Membrane proteins are of broad interest since they constitute a large fraction of the proteome in all organisms, up to 20-30%. They play a crucial role in many cellular processes mediating information flow and molecular transport across otherwise nearly impermeable membranes. Traditional three-dimensional structural analyses of membrane proteins are difficult to perform, which makes studies of other structural aspects important. The topology of an α-helical membrane protein is a two-dimensional description of how the protein is embedded in the membrane and gives valuable information on both structure and function.</p><p>This thesis is focused on predicting the topology of α-helical membrane proteins and on assessing and improving the prediction accuracy. Reliability scores have been derived for a number of prediction methods, and have been integrated into the widely used TMHMM predictor. The reliability score makes it possible to estimate the trustworthiness of a prediction.</p><p>Mapping the full topology of a membrane protein experimentally is time-consuming and cannot be done on a genome-wide scale. However, determination of the location of one part of a membrane protein relative to the membrane is feasible. We have analyzed the impact of incorporating such experimental information <i>a priori </i>into TMHMM predictions and show that the accuracy increases significantly. We further show that the C-terminal location of a membrane protein (inside or outside) is the optimal information to use as a constraint in the predictions.</p><p>By combining experimental techniques for determining the C-terminal location of membrane proteins with topology predictions, we have produced reliable topology models for the majority of all membrane proteins in the model organisms <i>E. coli </i>and <i>S. cerevisiae</i>. The results were further expanded to ~15,000 homologous proteins in 38 fully sequenced eukaryotic genomes. This large set of reliable topology models should be useful, in particular as the structural data for eukaryotic membrane proteins is very limited.</p>

<p>This thesis is focused on the synthesis and structural determination of a series of quasicrystal approximants in the <i>RE</i>₁₃Zn_~58 (<i>RE</i> = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), Ce₁₃Cd_~58and <i>RE</i>Cd₆ (<i>RE</i> = Tb, Ho, Er, Tm and Lu) systems. Structural studies were performed by single crystal X-ray diffraction methods.</p><p>The <i>RE</i>Cd₆ phases are 1/1 cubic approximants to the stable icosahedral quasicrystals. The structure of quasicrystals cannot be solved by conventional crystallography due to the lack of periodicity in three-dimensional space. On the other hand, quasicrystal approximants exhibit long-range order, which makes their structural determination possible by standard methods. Since they are believed to display the same local arrangement as the quasicrystals, the structures of the quasicrystal approximants play a key role in understanding quasicrystals.</p><p>The <i>RE</i>₁₃Zn_~58 and Ce₁₃Cd_~58 quasicrystal approximants show measurable compositional variations coupled to subtle structural differences. The crystal structures are generally rather more complex than previously reported, and exhibit a number of different ordering and disordering modes.</p>

<p>The synthesis, structural characterisation and the properties of the Zintl hydrides AeE₂H₂ and AeAlSiH (Ae = Ba, Ca, Sr; E = Al, Ga, In, Si, Zn) are reported. The first hydride in this class of compounds is SrAl₂H₂ which was discovered under an experiment by Gingl, who hydrogenated SrAl₂ at various temperatures. (Gingl et al, Journal of Alloys and Compounds 306 (2000) 127-132). The intention was to form alanates, e.g. AlH₄^-, by terminating the three dimensional four connected aluminium network in SrAl₂. The new hydride, SrAl₂H₂, has a partially conserved aluminium network. The three dimensional anionic network in SrAl₂ is reduced to two dimensions in the hydride, with aluminium bonded to both aluminium and hydrogen. This type of bonding configuration has not been observed before.</p><p>The hydrogenation of SrAl₂ is straight forward, 190 ^oC and 50 bar, compared to the difficult synthesis of alanates and alane, AlH₃. The latter synthesises uses aluminium in its zero oxidation state in contrast to the synthesis of SrAl₂H₂ from SrAl₂. (In the SrAl₂-precursor aluminium is reduced by the electropositive metal to -I.) Thus, the discovery shows a different route to alanates by using precursors with aluminium in a reduced state. If SrAl₂H₂is further hydrogenated at 250 ^oC the two dimensional network breaks and Sr₂AlH₇forms.</p><p>We wanted to investigate if SrAl₂H₂ was a singularity or if other similar compounds exist. We wanted to study how hydrogenation of precursors similar to the aluminide result in 1) new routes to compounds with high hydrogen content, as alanates, 2) to investigate how the E-H bond is affected as function of the network composition among different ternary hydrides, in particular BaAl_xSi_2-xH_x, and choice of active metal.</p><p>BaGa₂H₂ and SrGa₂H₂, two hydrides isostructural with SrAl₂H₂, were synthesized from its precursors BaGa₂ and SrGa₂. In addition three ternary hydrides BaAlSiH, CaAlSiH and SrAlSiH were manufactured from their related AeAlSi precursors.</p><p>All powders were characterized by neutron and x-ray diffraction methods.</p><p>An increased stability towards water/moisture compared to ordinary saline hydrides was noticed, especially for the ternary hydrides. Heat stability was measured with DSC (differential scanning calorimetry). The hydrides BaGa₂H₂ and SrGa₂H₂ decompose around 300 ^oC at 1 atm. This is similar to isostructural SrAl₂H₂. The ternary hydrides BaAlSiH and SrAlSiH decompose at 600 ^oC, at 1 atm, which is the highest noticed temperature for compounds with Al-H bonds. Inelastic neutron scattering experiments showed that these hydrides Al-H and Sr-H bonds are really weak, even weaker then the Al-H interactions in alanates and alanes. These hydrides are probably stabilized be their lattices. The electric properties among the ternary hydrides were measured with IR-spectroscopy (diffuse reflectance). The ternary hydrides, AeAlSiH, are indirect semi conductors. BaGa₂H₂ and SrGa₂H₂are conductors. The ternary hydrides, AeAl_xSi_2-xH_x, may have adjustable band gaps, which we were not able to determine.</p><p>This work is leading into a new research area within the field of metal hydrides.</p>

<p>This thesis is focussing on the crystallographic challenges and what knowledge we can gain from studying the different open-framework germanates. Five new open-framework germanates have been synthesized and the structures have been determined by single crystal X-ray diffraction. A thorough description is made of the different problems raised with the different compounds, whether it is choice of crystal system in SU-61, twinning and possible ordering in SU-46, superstructure and variation in elemental content in SU-57, template disorder in JLG-5 or framework disorder in SU-44.</p><p>Open-framework germanates are often built from one type of cluster, such as the Ge₇ [Ge₇X₁₉], Ge₈ [Ge₈X₂₀], Ge₉ [Ge₉X_n, n =25-26] and Ge₁₀ [Ge₁₀X₂₈], (X =O, OH, F) clusters. The structures built by clusters containing different kinds of polyhedra are discussed, with a focus on the 4-coordinated Ge₇ clusters, the larger cluster aggregate found in SU-8 and SU-44 and the structures built by the Ge₁₀ clusters.</p>

<p>For the vast majority of proteins no experimental information about the three-dimensional structure is known, but only its sequence. Therefore, the easiest way to obtain some understanding of the structure and function of these proteins is by relating them to well studied proteins. This can be done by searching for homologous proteins. It is easy to identify a homologous sequence if the sequence identity is above 30%. However, if the sequence identity drops below 30% then more sophisticated methods have to be used. These methods often use evolutionary information about the sequences, which makes it possible to identify homologous sequences with a low sequence identity.</p><p>In order to build a three--dimensional model from the sequence based on a protein structure the two sequences have to be aligned. Here the aligned residues serve as a first approximation of the structure.</p><p>This thesis focuses on the development of fold recognition and alignment methods based on evolutionary information. The use of evolutionary information for both query and target proteins was shown to improve both recognition and alignments. In a benchmark of profile--profile methods it was shown that the probabilistic methods were best, although the difference between several of the methods was quite small once optimal gap-penalties were used. An artificial neural network based alignment method ProfNet was shown to be at least as good as the best profile--profile method, and by adding information from a self-organising map and predicted secondary structure we were able to further improve ProfNet.</p>

<p>I detta examensarbete undersöktes hur ett kemiprov inom området kemisk jämvikt utformades och bedömdes på en gymnasieskola i Mellansverige. De två lärarna som utformade och bedömde provet intervjuades och fick svara på frågor via e- mail. Både intervjudata och frågorna via e-mail kategoriserades med hjälp av Selgheds (2006) kategorier rörande synsätt på betygsystemet. Resultatet visade att lärarna har olika synsätt på både provets utformning och bedömning trots att dem tillsammans konstruerat både prov och facit. Lärarna täckte med detta prov flera av de kända missuppfattningar som den didaktiska forskningen funnit, även om det inte var på ett systematiskt sätt. Istället visade resultatet att det fanns risk att missförstånd skall uppstå. Denna undersökning kan kompletteras med elev- och undervisningsperspektivet för att undersöka vilka konsekvenser det får om lärarna behandlar den didaktiska forskningen mer systematiskt.</p>