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- Dong, Hai, 1971-
(författare)
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Efficient Carbohydrate Synthesis By Intra- and Supramolecular Control
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In this study, the effects of the neighboring group on the Lattrell-Dax inversion were explored. A new carbohydrate/anion host-guest system was discovered and the ambident reactivity of the nitrite anion was found to cause a complicated behavior of the reaction. It has been demonstrated that a neighboring equatorial ester group plays a highly important role in this carbohydrate epimerization reaction, restricting the nitrite N-attack, thus resulting in O-attack only and inducing the formation of inversion compounds in good yields. Based on this effect, efficient synthetic routes to a range of carbohydrate structures, notably β-D-mannosides and β-D-talosides, were designed by use of double parallel and double serial inversion. A supramolecularly activated, triggered cascade reaction was also developed. This cascade reaction is triggered by a deprotonation process that is activated by anions. It was found that the anions can activate this reaction following their hydrogen bonding tendencies to the hydroxyl group in aprotic solvents.
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| 2. |
- Alpenberg, Jan, 1964-, et al.
(författare)
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Arbetsmiljöinvesteringar i mindre företag : - projektering och uppfattade effekter utifrån Arbetslivsfondens satsningar
- 1996
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals primarily with the relationship between investments in working environment and the outcome and apprehended effects of these investment activities in small firms. A main concern in this aspect is what effects investments in working environment might have on efficiency in the companies. Another area of focus in this thesis is whether and to what extent external subsidies affect attitudes and investment behaviour, as well as stimulate change and development activities in small firm? The thesis is based on a study of planning and apprehended effects of investments in working environment whithin the context of the Swedish Workinglife Fund. The Swedish Workinglife Fund was established in 1989 to stimulate investments in areas such as organizational development, competency formation, rehabilitation and physical equipment and machinery in order to improve the working environment in companies and different public organisations. In order to investigate the questions of this study two emprical studies has been conducted. The results from these studies indicate that investments with an ambition to improve the working environment in many cases created opportunities for increased economic efficiency and that projects with a comprehensive approach tends to have the greatest potential. The study also indicates marginal use of formal investment appraisal methods (including pay-back) in the decision process. Finally the results indicate that subsidies tend to fasten (push) the starting point and making each project more comprehensive in terms of size and complexity.
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| 3. |
- Dunér, Gunnar, 1980-
(författare)
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Signal Enhancement by Dynamic Polymers in Quartz Crystal Microbalance Applications
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This licentiate thesis presents studies of signal enhancement by dynamic polymers in quartz crystal microbalance (QCM) applications. The aim of the study has been to determine the potential for the use of polymers on QCM sensors for signal enhancement in molecular interaction studies. A method for synthesis of polymer sensor surfaces on QCM substrates was developed based on an iniferter photo polymerization technique. Polymerized poly(acrylic acid) and poly(acryl amide) surfaces were extensively characterized with electron spectroscopy for chemical analysis (ESCA), infrared reflection absorption spectroscopy (IRAS) and atomic force microscopy (AFM). The QCM response dynamics of these surfaces to pH changes was studied and the carboxyl containing surfaces exhibited large, reversible and highly reproducible frequency shifts due to expansion of deprotonated polymer chains. Surface acid dissociation constants (pKa) were determined for poly(acrylic acid) surfaces, carboxymethyldextran surfaces and self-assembled monolayer carboxyl surfaces by means of pH titration in QCM flow-through instrumentation. Surface pKa data was consistent with available literature data. The sensitivity enhancement for molecular interaction studies was investigated for poly(acrylic acid) coated QCM sensors with a model system consisting of immobilized biotin and an anti-biotin Fab fragment. Binding responses of antibiotin Fab to immobilized biotin was revealed to be 11 times higher than the corresponding results for a carboxylated SAM surface.
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