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In the search for a sustainable and environmentally friendly energy source, artificial photosynthesis has been proposed as a promising solution. Using water as a substrate, solar energy can be utilised to store energy in the chemical form of hydrogen fuel. In part of this global scientific effort, this thesis work focuses on enabling molecular dynamics simulations of a particular set of ruthenium centred water oxidation catalysts. The new catalysts show great success because of a binuclear reaction pathway in aqueous solution which makes it very interesting to model and investigate. Utilising quantum mechanical tools, a set of molecular mechanics force field parameters for Ru-involved bonds, angles, torsions, and partial charges was successfully obtained and examined. The work allows future large scale simulation of water oxidation and oxygen evolution in order to gain understanding and improve artificial photosynthesis.

In this study, quantum chemical methods have been used to study two isomers of the proposed high energy density material N8. It has been suggested as a green substitute for conventional solid rocket fuel. Several techniques were used to study the barrier height towards decomposition along reaction path of four N8 isomers. The potential energy surfaces around the transition states of two of the isomers were further investigated. Results show that the bond length of the isomers may have been overestimated, and one of the isomers has a lower barrier and may have a more complicated reaction route. Furthermore, there is a rather large difference in barrier height between calculations at the CCSD and CCSD(T) levels of theory I den här studien har kvantkemiska beräkningsmetoder använts för att studera två isomerer av N8. På grund av sitt höga energiinnehåll har N8 föreslagits som ett grönt alternativ till konventionellt fast racketbränsle. Flera tekniker har använts för att studera barriären för nedbrytning utefter reaktionskoordinaten för fyra N8-isomerer. Potentialytan runt aktiveringstillståndet för två av isomererna studerades närmare. Resultaten visar att bindningslängden hos isomererna kan ha överskattats och en av isomererna har en lägre barriär samt kan ha en mer komplicerad reaktionsväg. Vidare är det en tämligen stor skillnad i aktiveringsenergi mellan CCSD- och CCSD(T)- nivåerna.

The purpose of this study is to observe what modifying the surface of cellulose nanofibrils may imply for their interactions with a surrounding saline aqueous solution. This will be studied by using GROMACS, a molecular dynamic simulation software. In particular, we will analyse the modified surfaces hydrophilicity compared to native nanocellulose. This will subsequently have an impact on the nanofibrils readiness to aggregate to one another and disperse in the solution. Specifically two types of surface modifications will be studied, sulfonation and carboxy- lation. The hydrophilicity of the surfaces will be determined by analysing the density profiles of the systems wherein the modified surfaces interacts with the aqueous solutions. Also, the energies from the interactions of the simulated systems will be studied. We concluded that both modifications increases the surfaces interactions with the sur- rounding solution. Modifying the surface of the cellulose nanofibril with sulfonate will increase the surfaces attraction towards water and may provide the best rate of dispersion in aqueous solutions and best prohibit aggregation. Carboxylation of the surface provides similar hydrophilic results as the sulfonation but not as prevalent.

The purpose of this study is to observe what modifying the surface of cellulose nanofibrils may imply for their interactions with a surrounding saline aqueous solution. This will be studied by using GROMACS, a molecular dynamic simulation software. In particular, we will analyse the modified surfaces hydrophilicity compared to native nanocellulose. This will subsequently have an impact on the nanofibrils readiness to aggregate to one another and disperse in the solution. Specifically two types of surface modifications will be studied, sulfonation and carboxy- lation. The hydrophilicity of the surfaces will be determined by analysing the density profiles of the systems wherein the modified surfaces interacts with the aqueous solutions. Also, the energies from the interactions of the simulated systems will be studied. We concluded that both modifications increases the surfaces interactions with the sur- rounding solution. Modifying the surface of the cellulose nanofibril with sulfonate will increase the surfaces attraction towards water and may provide the best rate of dispersion in aqueous solutions and best prohibit aggregation. Carboxylation of the surface provides similar hydrophilic results as the sulfonation but not as prevalent.

In the search for a sustainable and environmentally friendly energy source, artificial photosynthesis has been proposed as a promising solution. Using water as a substrate, solar energy can be utilised to store energy in the chemical form of hydrogen fuel. In part of this global scientific effort, this thesis work focuses on enabling molecular dynamics simulations of a particular set of ruthenium centred water oxidation catalysts. The new catalysts show great success because of a binuclear reaction pathway in aqueous solution which makes it very interesting to model and investigate. Utilising quantum mechanical tools, a set of molecular mechanics force field parameters for Ru-involved bonds, angles, torsions, and partial charges was successfully obtained and examined. The work allows future large scale simulation of water oxidation and oxygen evolution in order to gain understanding and improve artificial photosynthesis.

Thermodynamically, native cellulose nano fibrils are more stable in an aggregated state. The aggregated state is however not useful from a material development perspective. Therefore much research has been done to stabilize the dispersal of the fibrils. One method to overcome this instability is by surface substitution of the O6 hydroxyl group with carboxylate groups, to make highly charged fibrils in aqueous solutions. It is therefore of much interest to understand the interaction of highly charged fibrils in aqueous solutions. In this study, we aim to model the interaction potential energy between native and surface modified cellulose nanofibrils in order to understand under what conditions the contribution from the dipole interactions can be neglected. To achieve this we propose to use a continuum electrostatic approach, modeling the electrostatic interactions as a function of the fibrils relative dipole orientation, separation, surface charge as well as ionic strength of the solution, by means of using the Poisson-Boltzmann equation.

in UndeterminedAn inventory is described of Rubus sect. Corylifolii from the province of Halland in south-west Swe- den. About 850 localities have been visited and field studies have been combined with chromo- some counting and random amplified polymorphic DNA studies. Ten traditional species have been observed, as well as six local species, two with over70 localities each. The other four have 4–15 locali- ties. Hybrids with R. idaeus have been observed at four localities and hybrids with R. caesius have been found at 27 localities. These hybrids have previously been called R. pruinosus and R. cyclomorphus, but it is shown that they are polymorphous and do not show any distinct distribution. Only two specimens have been impossible to classify. One is probably introduced, whereas the other might be a derivative of a hybrid.