<p>The interest for polypropylene/cellulose composites has experienced a great increase in different applications such as car interiors and construction materials. Cellulose fibres are inexpensive, renewable, biodegradable, they present lower density and their mechanical properties can be compared to those of inorganic fillers. However, several factors must be considered when designing polypropylene/cellulose composites: the poor compatibility between the hydrophilic fibres and the hydrophobic thermoplastic matrix leads to a weak interface, which has to be improved by coupling agents; the hydrophilic nature of the fibres makes them very sensitive towards water absorption, which also leads to a loss of properties and swelling with subsequent dimensional instability; the reduced thermal stability of cellulose fibres leads to degradation of the fibres at thermoplastic processing temperatures producing odours in the final material; and finally the properties of composites are greatly influenced by the structure, size and quality of the fibres.</p><p>Pulp fibres modified by different methods in order to enhance the compatibility fibre-matrix, were tested. Modified fibres led to improved mechanical properties and thermal behaviour when used in composites with recycled polypropylene.</p><p>Four different types of natural fibres were used as reinforcement in two different polypropylene types: virgin and recycled polypropylene. The mechanical properties of the composites were mostly dependent on the fibre loading and slightly dependent on the type of fibre. Moreover, water absorption kinetics was studied by the Fickian diffusion theory. After absorption, a remarkable loss of properties was observed.</p><p>Hydrolysed cellulose fibres showed a greater enhancing effect on polypropylene than non-hydrolysed cellulose fibres. This is attributed to the greater mechanical properties of reduced cellulose structures.</p><p>The effect of using cellulose fibres in PP/clay nanocomposites was also studied. The interaction between the clay particles and the cellulose fibres and the combined effect of both reinforcements were believed to be the main reasons for the enhancing properties.</p>

<p>In this thesis oxidative coupling of H-phosphonate and H phosphonothioate diesters with different alcohols and amines are presented. Since the reactions with alcohols previously have been particularly unfavourable due to competing side reactions, a modified protocol leading to high coupling yields of structurally diverse hydroxylic components was developed. The phosphorylation reaction was studied using ³¹P NMR spectroscopy and for the first time the previously only postulated reactive intermediate involved in these reactions was observed. </p><p>The use of iodine in combination with a bulky chlorosilane in pyridine was found to have a profound effect on both the suppression of side reactions and the rate of the oxidative couplings, and led to a clean formation of phosphorylated products in high yields. This synthetic protocol was then extended to include coupling reactions with bis-functional reagents containing hexamethylene linkers to provide handles for derivatisations of oligonucleotides.</p><p>A synthetic protocol consisting of the stereospecific oxidative coupling of amines with H-phosphonate diesters to produce phosphoroamidates was designed in such a way that it permitted control of the stereochemical outcome of the reactions.</p><p>Based on a silylation-mediated reaction utilising phenyl H phosphonothioate monoester as a thiophosphonyl transferring agent, a method was developed and used for the preparation of H-phosphonothioate building blocks for the synthesis of DNA analogues.</p>

Studiens syfte är att synliggöra hur elever i årskurs 4-5 beskriver och karaktärisera begreppen fast, flytande och gasform. Studien ämnar även att lyfta fram vilka uppfattningar elever har om materiens fasövergångar.   Studien är kvalitativ och baseras på semistrukturerade intervjuer. Intervjuerna genomfördes på en skola i södra Sverige, där 20 elever från årskurs 4 och 5 deltog i undersökningen.    Resultatet i denna studie visar att det finns en variation i elevers beskrivande och hur de karaktärisera begreppen fast-, flytande- och gasform. Resultatet visar att eleverna beskriver och karaktärisera begreppen fast, flytande och gas på två nivåer, det de kan se och uppleva (yttre egenskaper), samt det som de inte kan se (inre egenskaper) med blotta ögat. Det som framkom är att eleverna främst väljer att beskriva begreppen med yttre egenskaper först där de utgår från vad de kan se och sina upplevelser av materiens faser. Vidare visar resultatet att det finns svårigheter för elever att kategorisera vilken fas materien befinner sig i vid kategorisering av konkret rekvisita.     I resultatet av elevernas uppfattningar om fasövergångarna upptäcktes det sex kategorier i studien: förflyttning av materia, förklaring som inte beskriver processen, förklaring med fasövergångens process, animistiska beskrivningar, kemisk reaktion och förändring i partiklarnas storlek. Elevernas uppfattningar är varierande och visar att det finns brister i begreppsbildningen för faserna och fasövergångarna. En annan brist som också upptäcks är förståelsen för massans bevarande.

Syftet med denna studie är att få en inblick i bedömning av laborationer i kemi och vilka svårigheter som kan finnas med det. Studien är kvalitativ och har fyra stycken forskningsfrågor som besvaras i resultatdiskussionen. Vad är lärares motiv till att genomföra laborationer i kemi? Vilka utmaningar ser lärare med laborationer i kemi? Hur ser lärare på bedömning av laborationer i kemi? Vilken/vilka bedömningsmetoder använder sig lärare av när de bedömer laborationer i kemi? För att ta reda på detta genomfördes 6 intervjuer med verksamma lärare i åk 4-9. Alla lärare är behöriga i ämnet NO och arbetade som NO-lärare när intervjuerna genomfördes. Det visade sig att flera lärare bedömde eleverna genom att göra observationer av laborationerna, de använde dock olika metoder för att dokumentera den kunskap eleverna visade sig ha. Lärarna använde laborationer i kemi till största del för att befästa elevernas kunskaper på ett effektivt sätt. I vissa avseende, som till exempel vid frågan om vad de ser att elevernas största utmaning med laborationer i kemi är, hade lärarna liknande svar. I andra avseenden, som exempelvis vid frågan om vad de själva ser som sin största utmaning vid laborationer i kemi, hade lärarna skilda svar.

Syftet med detta examensarbete är att beskriva barns uppfattning och språkliga förändringar när de får undersöka vattnets faser. Examensarbetet utgår ifrån det sociokulturella perspektivet tillsammans med fenomenografi och grundas på kvalitativa observationer av två olika barngrupper som genomfört experiment och reflektionssamtal ledda av en förskollärare. De två barngrupperna har observerats under en dag där de genomfört experimentet under två tillfällen för att undersöka hur deras språk förändras genom aktiviteter relaterade till det specifika lärandeobjektet, vattnets aggregationstillstånd. Mellan de två experimenttillfällena har reflektionssamtal genomförts där barnen fått möjlighet att prata om det som upplevts. Studien genomfördes med barn i åldern två till tre år och sammanlagt deltog nio barn. Resultatet av studien pekar på en förändring i barns språk där nya begrepp och ett ökat ordförråd hjälper dem till en ökad förståelse för sin omvärld och det specifika fenomenet, vattnets aggregationstillstånd. Molekyler, temperatur, fast form, flytande form, gasform är ord som barnen enligt resultatet uppmärksammade och använde sig av. Resultatet pekar också på att ett samspel mellan barn kan generera ett ökat ord- och begreppsförråd. Även förskollärares vägledande frågor och medforskande visade sig skänka stöttning till barns språkutveckling. / The purpose of this study is to define children’s transformation of language when exploring the aggregational states of water. The theoretical frame is the socio-cultural perspective and phenomenography. The study is an observational study based on children’s participation in experiments and reflective conversations, all lead by pre-school teachers. Two separate groups of children have been observed for one day each when participating in the same experiment at two different times, to be able to tell if any difference in their perception and language can be seen through activities related to the object of learning. Reflective conversations have been held in between the experiments to give the children the opportunity to discuss what they experienced. Nine children at the age of two to three years old has been part of the study. The result of the study shows a change in children’s language. Words and concepts they have learned helps them to an increased understanding of their surroundings and the specific phenomenon, the aggregational states of water. Molecules, temperature, solid form, liquid form, gaseous form are words that the children noticed and used according to the result. The result also indicates that an interaction between children can generate an increased vocabulary. Preschool teachers' guiding questions and co-research also proved to support children's language development.

<p>This work is part of a research program where the aim is to develop an</p><p>electroanalytical technique to determine the amount of dissolved oxide and hydroxide in industrial Mg electrolytes. The systems studied were mixtures of MgCl₂ and NaCl, ranging from pure MgCl₂ to melts containing 10 mole % MgCl₂ / 90 mole % NaCl. To these melts, additions of MgO and MgOHCl were done at temperatures ranging from 475 to 850°C. Voltammetric measurements were performed before and after addition of MgO or MgOHCl and melt samples were taken for analysis. The quenched melt samples wereanalysed by carbothermal reduction analysis and the acid consumption method to obtain the O^2- and OH^-contents in the samples. Linear sweep voltammetry was performed with a sweep rate of 200 mV/sec in two potential regions to detect the concentration of dissolved MgOHCl and MgO. The experiments were performed inside a glove box having water and oxygen contents of, respectively, <1 ppm and <2 ppm. The results indicate that the rate of decomposition of MgOHCl increases with increasing temperature, as expected. In melts with high content of NaCl the underpotential deposition of sodium has a large influence on the uncertainty in the reading of the current density of MgOHCl reduction. Linear relations between MgO and MgOHCl concentrations and the peak current densities for the electrochemical reactions of the dissolved MgO and MgOHCl species in the melt, respectively, were observed. The diffusion coefficients of MgO and MgOHCl in the different melts were calculated. The diffusion coefficients decrease with increasing content of MgCl₂. For MgOHCl the diffusion coefficient decreases from 5.6*10^-5 cm²/sec in 20 mole % MgCl₂ / 80 mole % NaCl to 2.1*10^-5 cm²/sec in pure MgCl₂, both measurements done at 800°C. For MgO the diffusion coefficient decreases from 6*10^-5 cm²/sec in 41.5 mole % MgCl2 / 58.5 mole % NaCl to 0.8*10^-5 cm²/sec in pure MgCl₂, both measurements done at 730°C. The results show that it is possible to use cyclic voltammetry for quantitative analysis of MgOHCl in MgCl₂based melts.</p>

<p>This thesis investigates three different surface modifications, and the route to design and synthesize them. The thesis is therefore divided into three sub- projects. (i.) Design and synthesis of a peptide which secondary structure could be controlled by a negatively charged surface. (ii.) Design and synthesis of a cyclic peptide, that would self-organize prior to surface interaction, using the type I anti-freeze protein of a winter flounder as template. (iii.) The use of solid-phase synthesis to make the synthesis of SAM-molecules easier.</p>

<p>The objective of this work was to explore fundamental aspects of utilizing (DZ) and (ZD) bleaching stages in the prebleaching of oxygen delignified Scandinavian softwood kraft pulp, and compare paper properties of fully bleached pulps with a DEoD₁ED₂ bleached EDF reference pulp. According to the literature, the use of chlorine dioxide and ozone in combination in (DZ) and (ZD) bleaching stages seems advantageous from both environmental and economical points of view. A significant reduction in the formation of chloro-organic compounds and efficient delignification relative to chemical consumption is obtained. </p>

<p>The objective of this work has been to study equilibrium and non equilibrium situations during high pressure gas processing operations with emphasis on utilization of the high reservoir pressure. The well stream pressures of some of the condensate and gas fields in the North Sea are well above 200 bar. Currently the gas is expanded to a specified processing condition, typically 40-70 bar, before it is recompressed to the transportation conditions. It would be a considerable environmental and economic advantage to be able to process the natural gas at the well stream pressure. Knowledge of thermodynamic- and kinetic properties of natural gas systems at high pressures is needed to be able to design new high pressure process equipment. </p><p>Nowadays, reactive absorption into a methyldiethanolamine (MDEA)solution in a packed bed is a frequently used method to perform acid gas treating. The carbon dioxide removal process on the Sleipner field in the North Sea uses an aqueous MDEA solution and the operation pressure is about 100 bar. The planed carbon dioxide removal process for the Snøhvit field in the Barents Sea is the use of an activated MDEA solution. </p><p>The aim of this work has been to study high-pressure effects related to the removal of carbon dioxide from natural gas. Both modelling and experimental work on high-pressure non-equilibrium situations in gas processing operations have been done. </p><p>Few experimental measurements of mass transfer in high pressure fluid systems have been published. In this work a wetted wall column that can operate at pressures up to 200 bar was designed and constructed. The wetted wall column is a pipe made of stainless steel where the liquid is distributed as a thin liquid film on the inner pipewall while the gas flows co- or concurrent in the centre of the pipe. The experiments can be carried out with a well-defined interphase area and with relatively simple fluid mechanics. In this way we are able to isolate the effects we want to study in a simple and effective way. </p><p>Experiments where carbon dioxide was absorbed into water and MDEA solutions were performed at pressures up to 150 bar and at temperatures 25 and 40°C. Nitrogen was used as an inert gas in all experiments. </p><p>A general non-equilibrium simulation program (NeqSim) has been developed. The simulation program was implemented in the object-oriented programming language Java. Effort was taken to find an optimal object-oriented design. Despite the increasing popularity of object-oriented programming languages such as Java and C++, few publications have discussed how to implement thermodynamic and fluid mechanic models. A design for implementation of thermodynamic, mass transfer and fluid mechanic calculations in an object-oriented framework is presented in this work. </p><p>NeqSim is based on rigorous thermodynamic and fluid mechanic models. Parameter fitting routines are implemented in the simulation tool and thermodynamic-, mass transfer- and fluid mechanic models were fitted to public available experimental data. Two electrolyte equations of state were developed and implemented in the computer code. The electrolyte equations of state were used to model the thermodynamic properties of the fluid systems considered in this work (non-electrolyte, electrolyte and weak-electrolyte systems).</p><p>The first electrolyte equation of state (electrolyte ScRK-EOS) was based on a model previously developed by Furst and Renon (1993). The molecular part of the equation was based on a cubic equation of state (Scwarzentruber et.al. (1989)’s modification of the Redlich-Kwong EOS) with the Huron-Vidal mixing rule. Three ionic terms were added to this equation – a short-range ionic term, a long-range ionic term (MSA) and a Born term. The thermodynamic model has the advantage that it reduces to a standard cubic equation of state if no ions are present in the solution, and that public available interaction parameters used in the Huron-Vidal mixing rule could be utilized. The originality of this electrolyte equation of state is the use of the Huron-Vidal mixing rule and the addition of a Born term. Compared to electrolyte models based on equations for the gibbs excess energy, the electrolyte equation of state has the advantage that the extrapolation to higher pressures and solubility calculations of supercritical components is less cumbersome. The electrolyte equation of state was able to correlate and predict equilibrium properties of CO₂-MDEA-water solutions with a good precision. It was also able to correlate high pressure data of systems of methane-CO₂-MDEA and water. </p><p>The second thermodynamic model (electrolyte CPA-EOS) evaluated in this work is a model where the molecular interactions are modelled with the CPA (cubic plus association) equation of state (Kontogeorgios et.al., 1999) with a classical one-parameter Van der Walls mixing rule. This model has the advantage that few binary interaction parameters have to be used (even for non-ideal solutions), and that its extrapolation capability to higher pressures is expected to be good. In the CPA model the same ionic terms are used as in the electrolyte ScRK-EOS. </p><p>A general non-equilibrium two-fluid model was implemented in the simulation program developed in this work. The heat- and mass-transfer calculations were done using an advanced multicomponent mass transfer model based on non-equilibrium thermodynamics. The mass transfer model is flexible and able to simulate many types of non-equilibrium processes we find in the petroleum industry. A model for reactive mass transfer using enhancement factors was implemented for the calculation of mass transfer of CO₂ into amine solutions. The mass transfer model was fitted to the available mass transfer data found in the open literature. </p><p>The simulation program was used to analyse and perform parameter fitting to the high pressure experimental data obtained during this work. The mathematical models used in NeqSim were capable of representing the experimental data of this work with a good precision. From the experimental and modelling work done, we could conclude that the mass transfer model regressed to pure low-pressure data also was able to represent the high-pressure mass transfer data with an acceptable precision. Thus the extrapolation capability of the model to high pressures was good. </p><p>For a given partial pressure of CO₂ in the natural gas, calculations show a decreased CO₂ capturing capacity of aqueous MDEA solutions at increased natural gas system pressure. A reduction up to 40% (at 200 bar) compared to low pressure capacity is estimated. The pressure effects can be modelled correctly by using suitable thermodynamic models for the liquid and gas. In a practical situation, the partial pressure of CO₂ in the natural gas will be proportional to the total pressure. In these situations, it is shown that the CO₂ capturing capacity of the MDEA solution will be increased at rising total pressures up to 200 bar. However, the increased capacity is not as large as we would expect from the higher CO₂ partial pressure in the gas.</p><p>The reaction kinetics of CO₂ with MDEA is shown to be relatively unaffected by the total pressure when nitrogen is used as inert gas. It is however important that the effects of thermodynamic and kinetic non- ideality in the gas and liquid phase are modelled in a consistent way. Using the simulation program NeqSim – some selected high-pressure non-equilibrium processes (e.g. absorption, pipe flow) have been studied. It is demonstrated that the model is capable of simulating equilibrium- and non-equilibrium processes important to the process- and petroleum industry.</p>

<p>The formation of surface films on electrodes in contact with non-aqueous electrolytes in lithium-ion batteries has a vital impact on battery performance. A basic understanding of such films is essential to the development of next-generation power sources. The surface chemistry, morphology and thermal stability of two typical anode and cathode materials, graphite and LiNi_0.8Co_0.2O₂, have here been evaluated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction, scanning electron microscopy and differential scanning calorimetry, and placed in relation to the electrochemical performance of the electrodes. </p><p>Chemical and morphological information on electrochemically formed graphite surface films has been obtained accurately by combining XPS measurements with Ar⁺ ion etching. An improved picture of the spatial organisation, including thickness determination of the surface film and characterisation of individual component species, has been established by a novel sputtering calibration procedure. The stability of the surface films has been shown to depend strongly on temperature and choice of lithium salt. Decomposition products from elevated-temperature storage in different electrolyte systems were identified and coupled to effects such as capacity loss and increase in electrode resistance. Different decomposition mechanisms are proposed for surface films formed in electrolytes containing LiBF₄, LiPF₆, LiN(SO₂CF₃)₂ and LiCF₃SO₃ salts.</p><p>Surface film formation due to electrolyte decomposition has been confirmed on LiNi_0.8Co_0.2O₂ positive electrodes. An overall surface-layer increase with temperature has been identified and provides an explanation for the impedance increase the material experiences on elevated-temperature storage. </p><p>Surface phenomena are clearly major factors to consider in selecting materials for practical Li-ion batteries.</p>