The nickel-rich cathode material Li[Ni0.8Mn0.1Co0.1]O2 is a much sought after material in Li-ion batteries for the future of electric vehicles due to its high specific capacity. However, it exhibits fast degradation during its use due to the interaction between the electrolyte and the cathode surface leading to capacity loss. In this thesis, the surface interaction of pristine and alumina coated NMC811, and NiO powder with electrolyte was investigated to observe difference in surface reactivity and if hydroxide groups on the surface could be a potential culprit in degradation. Thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) analysis were used to measure thermal properties, surface area and adsorptive properties respectively between pristine and coated powders but no distinct difference was found. A soaking experiment was performed to induce electrolyte degradation on the powders by soaking them in the electrolyte LP40 for a duration of two weeks at 50°C. The electrolyte and the soaked powders were thereafter investigated through various spectroscopy methods like Attenuated Total Reflection – Fourier Transform Infrared (ATR-FTIR) and Raman spectroscopy to find potential degradation products but were found insignificant or inconclusive difference. The electrochemical testing was performed on NMC811 half-cells at 3-4.2V and 3-4.4V with a 0.5C – rate. The coated heat-treated NMC811 was found to have the best cyclability at both potential ranges. In conclusion, the difference in surface reactivity of the pristine, coated, and coated heat-treated powders were found to be insignificant. However, the coated heat-treated NMC811 was found to have improved electrochemical performance at both potential ranges but it remains uncertain if hydroxide groups could be a culprit in the degradation.

No description available.

The recent emergence of earth-abundant iron(III)-photosensitizers with N-heterocyclic carbene ligands, exhibiting nanosecond ligand-to-metal charge-transfer states with suitable redox potentials to activate a broad range of substances, offers the possibility to convert sunlight into chemical substances, such as fuels or pharmaceuticals, in an environmentally friendly way. These complexes, however, often suffer from low yields of charge-separated products escaping the solvent cage, making such applications inherently inefficient. This behavior has been attributed to the fact that back electron transfer is a spin-allowed process in these systems, as both the charge separated as well as the ground state are doublet states. The back electron transfer may hence be slowed down by a heavy atom-induced spin-orbit coupling to a quartet charge-separated state. This hypothesis has recently been postulated to explain a thirty-fold increase in cage escape yield for the reductive excited state quenching of [FeIII(pthmeimb)2]+ (phtmeimb = phenyl [tris(3-methyl-imidaz-olin-2-ylidene)]borate) by substituted alkyl/aryl amines in dichloromethane compared to the same reactions in acetonitrile. The work conducted in this thesis aimed to shine light onto this spin-orbit coupling effect by either introducing heavy atoms in the quencher or the solvent and quantifying their influence on the cage escape yields for both reductive quenching using [FeIII(pthmeimb)2]+ and [FeIII(btz)3]3+ (btz = 4,4’-bis(1,2,3-triazol-5-ylidene), as well as for previously unaddressed oxidative quenching using [FeIII(pthmeimb)2]+ by use of steady-state as well as time-resolved spectroscopic experiments. The results in this thesis highlighted that heavy-atom induced spin-orbit coupling, if present, may only have a small influence on the cage escape yield and that this effect is unlikely to be the sole contributor of the previously observed increase in dichloromethane.

No description available.

<p>This thesis reports an investigation of how acid-base models are taught and understood in Swedish upper secondary school. The definition of the concepts of acids and bases has evolved from a phenomenological level to an abstract (particle) level. Several models of acids and bases are introduced in Swedish secondary school. Among them an ancient model, the Arrhenius model and the Brønsted model. The aim of this study was to determine how teachers handle these models in their teaching. Further, to investigate Swedish upper secondary students’ ideas about the role of chemistry models, in general, and more specific, of models of acids and bases. The study consisted of two parts. First, a study was performed to get an overview of how acids and bases are taught and understood in Swedish upper secondary schools. It consisted of three steps: (i) the most widely used chemistry textbooks for upper secondary school in Sweden were analysed, (ii) six chemistry teachers were interviewed, and, (iii) finally also seven upper secondary school students were interviewed. The results from this study were used in the second part which consisted of two steps: (i) nine chemistry teachers were interviewed regarding their pedagogical content knowledge (PCK) of teaching acids and bases, and (ii) a questionnaire was administered among chemistry teachers of 441 upper secondary schools in Sweden. The results from the interviews show that only a few teachers chose to emphasise the different models of acids and bases. Most of the teachers thought it was sufficient to distinguish clearly between the phenomenological level and the particle level. In the analysis of the questionnaire three subgroups of teachers were identified. Swedish upper secondary chemistry teachers, on the whole, had a strong belief in the Brønsted model of acids and bases. However, in subgroup one (47 %) teachers’ knowledge of how the Brønsted model differs from older models was limited and diverse. Teachers in subgroup two (38 %) and three (15 %) seemed to understand the differences between the Brønsted model and older models, but teachers in subgroup 2 did not explain the history of the development of acids and bases in their teaching. Instead they (as teachers in subgroup one) relied more on the content in the textbooks than teachers in the third subgroup. Implications for textbook writers, teaching, and further research are discussed.</p>

<p>Research concerning lignin has increased during the last years due to its renewability and ready availability in black liquor at pulp mills. Today, the kraft lignin found in black liquor is used as a fuel to gain energy in the recovery boiler at the mill. However, a new isolation concept, LignoBoost®, has enabled isolation of part of the lignin while allowing the use of black liquor as a fuel. This isolated lignin can be utilised as a fuel in, for example, thermal power stations or further upgraded to more value-added products. In this context, the most interesting value-added product is carbon fibre. The demand for carbon fibre has increased, but the biggest obstacle for a more extended use is the high production cost. About half of the production cost is related to the raw material.</p><p>In this work, the possibility of using kraft lignin as a precursor for carbon fibre production has been investigated through fundamental studies. Kraft lignins originating from birch, <em>Eucalyptus globulus</em>, softwoods and softwoods from liner production have been studied. By separating the lignin while still in solution in the black liquor, unwanted large particles such as carbohydrates can easily be removed. After isolation according to the LignoBoost process and purification with the use of an ion-exchanger, the lignins have been both chemically and thermally characterised. Identification of the released compounds at different temperatures has been performed because only 40% of carbon relative to original lignin remains, down from theoretical 60% after thermal treatment up to 1000°C. The main released compounds were phenols, as revealed by pyrolysis-GC/MS. Additionally, a pre-oxidation was done in order to try to stabilise the lignins. It was shown that an oxidation prior to the thermal treatment increases the yield by more than 10% and that the main release of compounds takes place between 400°C and 600°C. Fractionated lignin is better qualified as raw material for carbon fibre production because it is purer and its softening temperature can be detected. Fractionated kraft lignins from all investigated wood sources have high possibilities to act as precursors for the manufacture of carbon fibre.</p>

<p>The positron emitting 68Ga radionuclide (T1/2 = 68 min) has the potential of practical interest for clinical PET. The metallic cation, 68Ga3+, is suitable for complexation reactions with chelators either naked or conjugated with macromolecules such as peptides and oligonucleotides. Such labeling procedures require pure and concentrated radiometal preparations, which cannot be sufficiently fulfilled by the presently available 68Ge/68Ga generator eluate. This thesis presents a method to increase the concentration and purity of 68Ga obtained from a commercial 68Ge/68Ga generator. DOTATOC (DOTA = 1,4,7,10-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid, TOC = D-Phe1-Tyr3–Octreotide) was used as a test molecule for comparing the labeling properties of different 68Ga preparations. In addition, DOTA-RDG (RGD = Cys2-6; c[CH2CO-Lys(DOTA)-Cys-Arg-Gly-Asp-Cys-Phe-Cys]-CCX6-NH2) and NODAGATATE (NODAGA = 1,4,7-triazacyclononane-1,4,7-triacetic, TATE = Tyr3 - Octreotate) were used to prove the concept. The use of the concentrated and purified 68Ga eluate along with microwave activation allowed quantitative 68Ga-labelling of peptide conjugates of ≤1 nanomolar quantities within 10 min. The specific radioactivity of the radiolabelled peptides was improved by a factor of >100 compared to previously applied techniques using non-treated generator eluate and conventional heating. A commercial 68Ge/68Ga generator in combination with this method for purification, concentration and microwave activated labeling resulted in a kit technology for 68Ga-tracer production.Four 17-mer oligonucleotides modified and functionalised with an hexylamine group in the 3'- or 5'- position were conjugated with DOTA and labelled with 68Ga using microwave activation. Chemical modification of the oligonucleotide backbone or sugar moiety did not influence the labelling nor the hybridisation ability of the oligonucleotides. However, the radioactivity organ biodistribution in rats differed dependent on the oligonucleotide structure. This indicated that metabolism and non-specific binding were affected by the backbone and sugar moiety structure.</p>

<p>Carbohydrates are a complex group of biomolecules with a high structural diversity. Their almost omnipresent occurrence has generated a broad field of research in both biology and chemistry. This thesis focuses on three different aspects of carbohydrate chemistry, synthesis, structure elucidation and the conformational analysis of carbohydrates.</p><p>The first paper describes the synthesis of a penta- and a tetrasaccharide related to the highly branched capsular polysaccharide from <i>Streptococcus pneumoniae </i>type 37. In the second paper, the structure of the O-antigenic repeating unit from the lipopolysaccharide of <i>E. coli </i>396/C1 was determined along with indications of the structure of the biological repeating unit. In addition, its structural and immunological relationship with <i>E. coli</i> O126 is discussed. In the third paper, partially protected galactopyranosides were examined to clarify the origin of an intriguing ⁴<i>J</i>_HO,H coupling, where a <i>W</i>-mediated coupling pathway was found to operate. In the fourth paper, the conformation of methyl a-cellobioside is studied with a combination of molecular dynamics simulations and NMR spectroscopy. In addition to the expected syn-conformation, detection and quantification of anti-<i>ø </i>and anti-<i>ψ</i> conformers was also possible.</p>

<p>Hydrophobins are a class of small proteins (7-15kDa) found in filamentous fungi and are among the most surface active proteins known today. Because of this they have received attention for different applications, e.g. for the food industry as an alternative in emulsions. The goal of this project was to culture and extract hydrophobins from <em>Trichoderma reesei</em> and characterize it. This was done from a freeze-dried culture of <em>Trichoderma reesei</em>, which was cultured on PDA-plates and in liquid medium with glucose as carbon source. Extraction was made by breaking the cells, mechanically and by sonication, and then by shaking a seperating funnel to create foam from the surface-active proteins. The foam was washed and freeze-dried and the total protein concentration of the freeze-dried substance was determined with Bradford assay and the hydrophpbin was characterized with SDS-PAGE. The culturing of the fungi was successful. The amount of foam created was, however, less than expected. The Bradford assay gave a total protein concentration of 7.5% in the freeze-dried substance, but the SDS-PAGE didn't give any results. The reason for this probably depends on the culturing and the extraction of the hydrophobin. <em>T. reesei</em> hydrophobin HFBI, expressed in glucose containing media, is bound to the mycelium of the fungi and the breaking of the mycelium might not have been enough to release all the protein, which also would explain the small amounts of foam. One way to improve this could be to grow the fungi on lactose instead. This will result in that T. reesei produces HFBII instead, which is mainly released to the surrounding. The conclusion of the project is that the method for culturing and extraction needs to be improved to obtain hydrophobin from <em>T. reesei</em>.</p>

In this thesis, density functional theory (DFT) is used to investigate the mechanisms and reactivities of electrophilic and nucleophilic aromatic substitution reactions (SEAr and SNAr respectively). For SEAr, the σ-complex intermediate is preceded by one (halogenation) or two (nitration) π-complex intermediates. Whereas the rate-determining transition state (TS) for nitration resembles the second π-complex, the corresponding chlorination TS is much closer to the σ-complex. The last step, the expulsion of the proton, is modeled with an explicit solvent molecule in combination with PCM and confirmed to be a nearly barrierless process for nitration/chlorination and involves a substantial energy barrier for iodination. It is also shown for nitration that the gas phase structures and energetics are very different from those in polar solvent. The potential energy surface for SNAr reactions differs greatly depending on leaving group; the σ-complex intermediate exist for F-/HF, but for Cl-/HCl or Br-/HBr the calculations indicate a concerted mechanism. These mechanistic results form a basis for the investigations of predictive reactivity models for aromatic substitution reactions. For SEAr reactions, the free energy of the rate-determining TS reproduces both local (regioselectivity) and global reactivity (substrate selectivity) with good to excellent accuracy. For SNAr reactions good accuracies are obtained for Cl-/HCl or Br-/HBr as leaving group, using TS structures representing a one-step concerted mechanism. The σ-complex intermediate can be used as a reactivity indicator for the TS energy, and for SEAr the accuracy of this method varies in a way that can be rationalized with the Hammond postulate. It is more accurate the later the rate-determining TS, that is the more deactivated the reaction. For SNAr reactions with F-/HF as leaving group, the same method gives excellent accuracy for both local and global reactivity irrespective of the degree of activation. / <p>QC 20170510</p>