Chapter I contains a brief introduction to the applications of dioxirane chemistry and outlines the mechanistic investigations carried out to date. Chapter 2 describes investigations into the dimethyldioxirane oxidation of para-substituted N,N-dimethylanilines in acetone. The N-oxides were found to be the only products. Relative rates were determined and compared with those of reactions with methyl iodide and other oxidants. The dimethyldioxirane reactions followed the Hammett relationship with a p value of -1.0. The reaction rates are strongly accelerated in the presence of water and the overall reaction mechanism is electrophilic in nature and does not involve free radical species or electron transfer. Chapter 3 looks at the regioselectivity of dimethyldioxirane when used to oxidise several polyfunctionalised nitrogenous drugs with a view to developing a system for use in oxidative degradation studies. The regioselectivity of dimethyldioxirane in the oxidation of polyhydroxy steroids, namely a series of bile acid methyl esters, is discussed in chapter 4. No evidence for preferential oxidation of axial over equatorial hydroxyls or vice versa was seen. Instead the least hindered hydroxyl at C3 was oxidised preferentially with some oxidation also occurring at C6 and C7. Hydroxyls at the sterically hindered C 12 were not oxidised. This provides further evidence for the proposed butterfly transition state. Finally, chapter 5 discusses the use of novel trifluoromethyl aryl ketones as promoters for Oxone®mediated epoxidations. 4-(trifluoroacetyl)benzoic acid was used succesfully and can be readily isolated for re-use by simple base extraction.

Molybdenum is very important in the life processes of both plants and animals. It acts as a catalyst in promoting and controlling many biological reactions in living cells, but exactly what it does and how it functions are not well understood. In the past because of the obvious complexity of the reactions concerned and the extremely minute quantities of molybdenum involved, its presence was long undetected. Lately, molybdenum has drawn special attention on account of its effects on metabolic processes, particularly of plants. In this regard, molybdenum has been shown to be present in four enzymes: nitrate reductase (JJ), xanthine oxidase (39), aldehyde oxidase (28), and hydrogenase (41).

The goal of this thesis was to summarize basic options of fiber spinning and manufacturing and their usability in industry. Methods of nanofiber spinning are described in the teoretical part, alongside the materials used in experimental part. The experimental part was focused on creating of workflow of defined nanofibers in laboratory enviroment, the possible modification of nanofibers with aditives. The release of aditives from different nanofibers into different enviroments was measured.

No / Four new polyhydroxylated sterols are isolated from Marine sponge Callyspongia fibrosa collected from the Gulf of Mannar, western Bay of Bengal (India). The structural assignment is based on 1H and 13C NMR spectra. All sterols are based on the known 24S-24-methyl cholesterol 1 which is also isolated, and contain 3b,6b-dihydroxy system and 25-O-acetate as common features (except in the case of sterol 6 that has a D25 in the place of 25-OAc). Additional OH substitution is also present at 5a in 4a and at 8b in 5. A further 12b-OH is present in 6 and 7. The hydroxylation pattern is so far known only in coral sterols but is without a precedent in sponge sterols. The major steroid 4a showed antimalarial activity against Plasmodium falciparum on the chloroquine-resistant stain better than on the chloroquine-sensitive strain.

I den här avhandlingen har vi studerat hur man kan göra nya tensider. En tensid är en speciell molekyl som har förmågan att lösa sig i både vatten och olja. Man kan göra följande experiment hemma: Fyll en glasburk till hälften med vatten och tillsätt en droppe matolja. Oljan bildar en droppe ovanpå vattnet, därför att vatten och olja inte är blandbara. Vatten är polärt och olja är opolärt. Om man rör om med en sked kommer oljedroppen förvisso att dela upp sig i mindre droppar, men så snart man slutar att röra kommer dessa att lägga sig på vattenytan igen. Sätt nu en droppe diskmedel till blandningen och rör om. Nu sprider sig oljedropparna mycket bättre i vattnet, och de lägger sig heller inte på vattenytan lika fort när man slutar att röra. Det här beror på att diskmedel innehåller en tensid, som har en polär och en opolär del. Den polära delen passar ihop med det polära vattnet, medan den opolära delen passar ihop med den opolära oljan. På så vis kan tensiden hjälpa till att lösa upp opolära ämnen i polära vätskor. Den aktiva delen av ett läkemedel består ofta av opolära ämnen, vilka inte löser sig i polära vätskor såsom vatten. Eftersom kroppen består till stor del av vatten måste man ändå försöka få läkemedlet vattenlösligt, för att möjliggöra transport via blodet till problemområdet. Det kan man uppnå genom att tillsätta tensider. Om läkemedel-tensidblandningen ska ges till djur eller människor får inte tensiden orsaka någon skada i kroppen. Vi har försökt framställa tensider som ska kunna användas för att just lösa läkemedel i vatten. För att kunna framställa nya tensider måste man ha kunskap i organisk syntes. Det betyder att man måste veta hur man från små intermediat (”byggstenar”) successivt kan bygga upp nya molekyler som har de önskvärda egenskaperna. Genom olika typer av organisk syntes har vi byggt upp tre nya tensidtyper, vars egenskaper vi studerat med olika mätningar. Ingen av dessa tensider lämpade sig som tillsats till läkemedel, men vårt arbete har givit mycket ny kunskap om hur framtida tensidmolkyler kan tillverkas och vilka egenskaper de får. / This thesis deals with the synthesis and characterization of new polyhydroxy surfactants. The first part describes the synthesis of three new surfactant classes, and the second part concerns the surface chemical characterization of the synthesized surfactants. A stereodivergent route for preparation of hydrophilic head groups was developed, that featured consecutive stereoselective dihydroxylations of a diene. This method provided in total four different polyhydroxylated head groups. These surfactant head groups were natural and unnatural sugar analogues, and were used for the coupling with two different hydrophobic tail groups. Another approach took advantage of a metathesis reaction and provided a polyhydroxylated compound that was coupled to 12-hydroxy stearic acid The third class of surfactants contained an amide linkage between the hydrophilic and the hydrophobic parts. The hydrophilic part consisted of two glucose units, and 12-hydroxy stearic acid was used as the hydrophobic part. The hydroxy moiety in the tail group was further functionalized as aliphatic esters, which provided in total four different surfactants. A selection of the surfactants was used to investigate the chiral discrimination in Langmuir monolayers at an air-water interface. The isotherms showed a remarkable difference in compressibility between diastereomeric surfactants and also a pronounced chiral discrimination between racemic and enantiomerically pure surfactants, favoring heterochiral discrimination. The monolayers were also investigated with Brewster angle microscopy (BAM) and grazing incidence X-ray diffraction (GIXD). It was not possible to observe any chirality dependent features from the BAM images, but the GIXD measurement supported the conclusion that heterochiral discrimination governed the intermolecular forces within the racemic monolayer. The third class of surfactants, containing an amide linkage between the glucose units and 12-hydroxy stearic acid was evaluated with respect to the CMC and the haemolytic activity. These surfactants were all haemolytic close to their respective CMC. / QC 20101015

<p>I den här avhandlingen har vi studerat hur man kan göra nya tensider. En tensid är en speciell molekyl som har förmågan att lösa sig i både vatten och olja.</p><p>Man kan göra följande experiment hemma: Fyll en glasburk till hälften med vatten och tillsätt en droppe matolja. Oljan bildar en droppe ovanpå vattnet, därför att vatten och olja inte är blandbara. Vatten är polärt och olja är opolärt. Om man rör om med en sked kommer oljedroppen förvisso att dela upp sig i mindre droppar, men så snart man slutar att röra kommer dessa att lägga sig på vattenytan igen. Sätt nu en droppe diskmedel till blandningen och rör om. Nu sprider sig oljedropparna mycket bättre i vattnet, och de lägger sig heller inte på vattenytan lika fort när man slutar att röra. Det här beror på att diskmedel innehåller en tensid, som har en polär och en opolär del. Den polära delen passar ihop med det polära vattnet, medan den opolära delen passar ihop med den opolära oljan. På så vis kan tensiden hjälpa till att lösa upp opolära ämnen i polära vätskor.</p><p>Den aktiva delen av ett läkemedel består ofta av opolära ämnen, vilka inte löser sig i polära vätskor såsom vatten. Eftersom kroppen består till stor del av vatten måste man ändå försöka få läkemedlet vattenlösligt, för att möjliggöra transport via blodet till problemområdet. Det kan man uppnå genom att tillsätta tensider. Om läkemedel-tensidblandningen ska ges till djur eller människor får inte tensiden orsaka någon skada i kroppen.</p><p>Vi har försökt framställa tensider som ska kunna användas för att just lösa läkemedel i vatten. För att kunna framställa nya tensider måste man ha kunskap i organisk syntes. Det betyder att man måste veta hur man från små intermediat (”byggstenar”) successivt kan bygga upp nya molekyler som har de önskvärda egenskaperna. Genom olika typer av organisk syntes har vi byggt upp tre nya tensidtyper, vars egenskaper vi studerat med olika mätningar. Ingen av dessa tensider lämpade sig som tillsats till läkemedel, men vårt arbete har givit mycket ny kunskap om hur framtida tensidmolkyler kan tillverkas och vilka egenskaper de får.</p> / <p>This thesis deals with the synthesis and characterization of new polyhydroxy surfactants. The first part describes the synthesis of three new surfactant classes, and the second part concerns the surface chemical characterization of the synthesized surfactants.</p><p>A stereodivergent route for preparation of hydrophilic head groups was developed, that featured consecutive stereoselective dihydroxylations of a diene. This method provided in total four different polyhydroxylated head groups. These surfactant head groups were natural and unnatural sugar analogues, and were used for the coupling with two different hydrophobic tail groups.</p><p>Another approach took advantage of a metathesis reaction and provided a polyhydroxylated compound that was coupled to 12-hydroxy stearic acid</p><p>The third class of surfactants contained an amide linkage between the hydrophilic and the hydrophobic parts. The hydrophilic part consisted of two glucose units, and 12-hydroxy stearic acid was used as the hydrophobic part. The hydroxy moiety in the tail group was further functionalized as aliphatic esters, which provided in total four different surfactants.</p><p>A selection of the surfactants was used to investigate the chiral discrimination in Langmuir monolayers at an air-water interface. The isotherms showed a remarkable difference in compressibility between diastereomeric surfactants and also a pronounced chiral discrimination between racemic and enantiomerically pure surfactants, favoring heterochiral discrimination. The monolayers were also investigated with Brewster angle microscopy (BAM) and grazing incidence X-ray diffraction (GIXD). It was not possible to observe any chirality dependent features from the BAM images, but the GIXD measurement supported the conclusion that heterochiral discrimination governed the intermolecular forces within the racemic monolayer.</p><p>The third class of surfactants, containing an amide linkage between the glucose units and 12-hydroxy stearic acid was evaluated with respect to the CMC and the haemolytic activity. These surfactants were all haemolytic close to their respective CMC.</p>

No description available.

The theoretical part is focused on evaluation of chosen ?essential? plastics used in the car industry. The principles of construction and proportioning of plastic components, basic conception of injection moulding and measuration follow. Another section of the theoretical part presents a summary of possible CAD systems, which are used. The practical part is focused on a particular plastic moulding. It includes the main description of a component with its material choice in dependence on the component function. Another section contains evaluation of the component complexity from the viewpoint of moulding, and a possible substitution of constructions, which could be productively simpler, is shown. The whole thesis is completed for better lucidity by pictures, drawings, and mechanical drawings.