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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Enantioselective Preparation of ω-Functionalized O-Acylated Cyanohydrins / Enantioselektiv framställning av ω-funktionaliserade O-acylerade cyanhydriner

Heid, Berenice January 2011 (has links)
A minor enantiomer recycling one-pot process usingω-functionalized prochiral aldehydes as starting materials and two reinforcing catalysts has been reported. The desired aldehyde for these process studies was 5-bromo-1-pentanal. In a two-phase solvent system, enzyme-catalyzed hydrolysis of the minor enantiomer regenerates continuously the prochiral starting material and Lewis acid catalysed addition of acetyl cyanide provides the O-acetylated cyanohydrins. The minor enantiomer recycling process has been studied and improved for 5-bromo-1-pentanal to receive high enantiomeric excess and yield of the expected O-acetylated cyanohydrin.
232

Odorant binding protein and olfactory receptors: plausible role as detectors in an odorant biosensor / Ett luktbindande proteins och luktreceptorers möjliga roll som detektorer i en biosensor

Bengtsson, Linda January 2011 (has links)
The development of an inexpensive, portable, stable, sensitive and selective biosensor for detection of odorants is a daunting task. Here, we hypothesized the development of a detector layer composed of the protein groups; the olfactory receptors (ORs) and the odorant binding proteins (OBPs), known to bind odorants in animal sensing. We report the design of 13 OR gene-vector constructs, and their subsequent transformation into Escherichia (E.) coli (BL21 (DE3)-STAR-pLysS) strain. Moreover, we report the expression of several ORs into an in vitro wheat germ extract using three separate detergent mixes for protein solubilization.   In addition, we describe the design of an odorant binding protein from the Aenopheles gambiae mosquito PEST strain (OBP-PEST) gene-vector construct under an IPTG (Isopropyl β-D-1-thiogalactopyranoside) inducible promoter. OBP-PEST was heterologously expressed in E.coli with an 8 amino acid long sequence (WSPQFEK) attached C-terminally, via a thrombin cleavage site and a flexible linker (GSSG). The WSPQFEK sequence, commonly referred to as a Strep-tag, enabled subsequent affinity chromatography purification of the protein, via binding to an engineered Streptavidin equivalent. Surprisingly, the OBP-PEST was found to contain a signal sequence leading to its truncation and secretion when expressed in E.coli.   Biophysical analyses were established using Circular Dichroism (CD) for the analysis of two lipocalins: Beta-lactoglobulin (BLG) and OBP-PEST. We studied the solubility, refoldability and the conformational transitions of BLG, as a result of change in solvent, pH and temperature. The secondary structure of OBP-PEST and its thermal stability was investigated.   In conclusion, this thesis work has enabled biophysical analyses of OBP-PEST and future analogs of interest to the development of a stable protein detector layer. Although further experiments are needed to fully characterize the biophysical properties, and to find odorant substrates of OBP-PEST, it was found to be a suitable alternative to ORs in a biosensor detector layer application. More importantly, an inherent OBP-PEST signal sequence was found to mediate protein secretion when expressed heterologously in E.coli. To the best of our knowledge this is the first lipocalin discovered to be secreted upon heterologous expression in E.coli.   We hypothesize that this signal peptide could be used as a means for targeted secretion and, hence, efficient protein purification.
233

Synthesis of novel 1.10-phenanthrolins and cyclic analogs, a potential anticancer and antimalarial agents / Syntes av 1.10-fenantroliner och cykliska analoger; potentiella anticancer och antimalaria substanser

Fouilland, Laura January 2011 (has links)
The potential antimalarial and anticancer effect of molecules containing 1,10-phenanthroline skeleton has been suspected on several previous studies. It is why the goal of this project is to synthesize novel 1,10-phenanthrolines and cyclic analogs. The originality of this project is the synthesis way of these novel compounds. Indeed, these structures will be obtained through an original redox approach developed in the SMITH laboratory using the tetrakis(dimethylamino)ethylene (TDAE) reagent.      The TDAE is an electron rich organic molecule which is an effective reducing agent capable of generating an anion from halogenated derivatives under mild conditions via a single electron transfer (SET). From the different substrate we will work with, the TDAE will generate an anion which will be additioned on the 1,10-phenanthroline-5,6-dione. These different substrates will be aromatic and heterocyclic nitro-benzylic, and quinonic derivates as well as bromodifluoromethyl heteroarylated substrates. A one pot two step (reduction, dehydration) reaction will be done on these addition products, in order to obtain a cyclised product.        It is the first time we try these reactions on these kind on molecules, it is why this project needs a lot of optimization and that the yield obtained are medium or equal to zero. However, we observed that the addition reaction with TDAE worked with 4 substrates out of 6. We tried the cyclisation reaction on only one addition product and we think that after some improvement of the reaction conditions and the work-up, we will be able to obtain the product with a good yield. / Tidigare studier har indikerat att molekyler med 1,10-phenanthrolineskelett har en skyddande effekt mot malaria och cancer. Syftet med detta projekt är att syntetisera nya 1,10-phenanthrolinar och cykliska analoger. Framställningsmetoden som användes i denna studie har inte undersökts tidigare.    Föreningen skapades genom en originalmetod utnyttjande en redoxreaktion med hjälp av en TDAE-reagens. TDAE är en elektronrik organisk molekyl och fungerar som en effektiv reduktionsagent. Med hjälp av en enelektronöverföring (SET) kan en anjon framställas under milda förhållanden utifrån halogena derivat. Anjonen tillförs 1,10-phenanthroline-5,6-dione. De olika substraten är heteroaromatiska nitro-benzyliska och quinoniska derivat, samt bromodifluorometylheteroarylerade. Cykliska produkter erhölls genom en tvåstegsreaktion (reduktion, dehydratisering) genomförd i ett enda reaktionskärl.   Med detta projekt har dessa reaktioner för första gången testats på den här typen av molekyler. Det krävs mer optimering eftersom utbytena var låga till medelhöga. Utav sex möjliga substrat fungerade additionsreaktionen med TDAE med fyra stycken. I detta försök testades dock endast en cyklisk reaktion på additionsprodukten. Med ytterligare förbättringar av reaktionsvillkor och upparbetningar förväntas man kunna producera önskad produkt i gott utbyte.
234

Synthesis of Ruthenium-based Water Oxidation Catalysts and Mechanistic Study

MOTOKI, YOSHIDA January 2015 (has links)
Two series of new mononuclear ruthenium complexes with hydrophobic or hydrophilic ligands [Ru(bda)L2] and [Ru(pdc)L3] (H2bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; H2pdc = 2,6-pyridinedicarboxylic acid; L = pyridyl ligands) were synthesized and their electrochemical properties and catalytic activity toward water oxidation were examined. It was revealed that the hydrophobic ligands introduced to [Ru(bda)L2 ] improved the catalytic performance, ahnost twofold TON and TOF values were achieved compared to the [Ru(bda)] catalyst with hydrophilic ligands. The cyclic voltammogram of [Ru(bda)L2] exhibited marginal difference between the catalysts with hydrophobic ligands and hydrophilic ones, implying that the hydrophobic ligands promoted the catalytic activity by :lacilitating formation of a reaction intermediate dimer.
235

Ett helt vanligt jävla hus : Urban building, Stadshagen, Stockholm / A ordinary block of flats? : Urban building, Stadshagen, Stockholm A new urban building with combined residential and commercial spaces above the north entrance to Stadshagens underground station, Kungsholmen, Stockholm, Sweden. In the proposal I explore residential flats with a modular room system and gangway entrances (loftgångar) combined with glazed balcony’s on the south facing facade. Thus enabling adaptable living arias that can be altered after the individual residents needs. The proposal also explores design alternatives for the buildings street facade, aiming at creating a organic facade within a system of prefabricated building components. The proposal also aims to comply with Swedish building standards and the building program for the assigned plot given by the city of Stockholm, incorporating office and retail spaces with the entrance to the underground station and a passageway to the adjacent Stadshagsparken.

Lotz, Felix January 2013 (has links)
Ett flerbostadshus med lägenheter och kommersiella ytor ovanför norra ingången till Stadshagens tunnelbanestation, Kungsholmen, Stockholm, Sverige. I förslaget undersöker jag bostäder med gemensamma inglasade söndervända loftgångar, och ett modulärt rums system. Detta för att göra lägenheternas bostadsaria anpassningsbar efter de boendes behov, och främja andrahandsuthyrning. Förslaget undersöker också olika alternativ för gatufasadens utförande, med målet att utforma en organisk fasad med prefabricerade byggnadselement. Målet i arbetet har varit att följa svensk standard och programmet som exploateringskontoret i Stockholm tagit fram för tomten i samband med markanvisningen som föreskriver utrymme för kontor och handel, samt nedgången till tunnelbanan och en passage till Stadshagsparken. / A new urban building with combined residential and commercial spaces above the north entrance to Stadshagens underground station, Kungsholmen, Stockholm, Sweden. In the proposal I explore residential flats with a modular room system and gangway entrances (loftgångar) combined with glazed balcony’s on the south facing facade. Thus enabling adaptable living arias that can be altered after the individual residents needs. The proposal also explores design alternatives for the buildings street facade, aiming at creating a organic facade within a system of prefabricated building components. The proposal also aims to comply with Swedish building standards and the building program for the assigned plot given by the city of Stockholm, incorporating office and retail spaces with the entrance to the underground station and a passageway to the adjacent Stadshagsparken.
236

Sustainable Synthesis of Allylic Ethers of Relevance for Biomaterials / Hållbar syntes av allyliska etrar av relevans för biomaterial

Ramström, Anja, Camaj, David, Lill, Malin, Carlsson, Robin January 2020 (has links)
Lignin is the most abundant source of naturally occurring aromatic compounds but has mainly been considered as waste material or energy source in the pulp and paper industry. However, due to the drive to find new material applications derived from renewable resources, there are extensive research activities aiming to develop new routes to utilize this source toward novel polymer materials. In this project, cinnamyl alcohol was used as a benchmark substrate in determining the most favorable reaction conditions for the optimal dehydrative etherification of allylic alcohols. The optimal reaction conditions determined for cinnamyl alcohol aimed to be applied to the etherification of the structurally similar, lignin-derived coniferyl alcohol to produce a bio-based allylic ether of relevance for biomaterial applications. However, due to the COVID-19 pandemic, the investigation of the etherification of coniferyl alcohol could not be conducted and the project had to be limited to the synthesis of 2-phenylethyl cinnamyl ether. Thus, this project serves as a pre-study for the sustainable etherification of lignin-derived allylic alcohols of relevance for biomaterials. The optimal reaction conditions for the synthesis of 2-phenylethyl cinnamyl ether was concluded to be 0.25 M cinnamyl alcohol and 1.00 M 2-phenylethanol as initial concentration of the reactants, 0.02 M Zr(Cp)2(OTf)2 ∙ THF as initial concentration of the catalyst, benzotrifluoride as solvent, a reaction mixture temperature of 60 °C, and a reaction time of four hours. Using optimized reaction conditions, coniferyl alcohol, a lignin-derived allylic alcohol, could in further research be evaluated as a sustainably sourced allylating agent with potential for biomaterial purposes.
237

Unga svenska TikTok-användare och konsumtion : Effekten av organisk marknadsföring av trendiga skönhetsprodukter som påverkar unga svenskars konsumtion / Young Swedish TikTok Users and Consumption : The Impact of Organic Marketing of Trendy Beauty Products on the Consumption Behavior of Young Swedes

Håkansson, Stina, Larsson, Maria January 2023 (has links)
This study includes an analysis and an understanding of the issue in the subject area of young adults in Sweden, TikTok, consumption and organic marketing. The purpose of the study is to examine how organic marketing on TikTok can influence young adults’ consumption, specifically of beauty products. By conducting research on the subject, we aim to contribute new insights regarding the impact that TikTok has on the consumption patterns of young Swedes when it comes to beauty products in Sweden. To enable this analysis, empirical qualitative data was collected, which was later analyzed using theories by, for example, Kotler et al. (2019), Denscombe (2021) and Fejes (2019). Data has been collected through interviews with young Swedish TikTok users and employees at two well-known beauty stores in Sweden. One key result that has emerged from this study is that young Swedes who use TikTok are significantly influenced by the content presented on this media platform. The results also show that TikTok users exhibit a higher tendency to resort to the consumption of beauty products to follow trends, join a community, and strive for similar appearances as the creators in the video clips. Therefore, the conclusion states that young Swedish TikTok users are influenced by consumption and different purchasing behaviors through organically marketed beauty videos, especially if the content of the video clips is engaging and informative. This is because these videos often inspire and create a desire for TikTok users to consume.
238

Prospective Life Cycle Assessment of an Electrochemical Hydrogenation Process Over a Nickel Foam Cathode / Prospektiv livscykelanalys av en elektrokemisk hydrogeneringsprocess över en nickelskumkatod

Appiah-Twum, Hanson January 2022 (has links)
The need for a safe and sustainable chemical industry has called for the development of emerging technologies with improved environmental performance. In this study, an emerging electrochemical hydrogenation process over Ni foam is being developed at the laboratory scale with an expectation of less environmental impacts than a conventional palladium on carbon hydrogenation process. To understand better the potential environmental performance of the process at the matured scale, a prospective life cycle assessment was conducted to identify environmental hotspots for early process improvement. There is no standardised method for prospective life cycle assessment, hence a methodological recommendation in conducting a prospective LCA was proposed through a literature review.  The proposed methodology consists of three steps which are a pre-inventory stage, an inventory stage, and a post-inventory stage. These steps have been connected to the ISO 14044 standard methodology for conducting an LCA where the pre-inventory stage relates to the goal and scope definition, the inventory stage to inventory analysis, and the post-inventory connected to both the inventory analysis, impact assessment, and interpretation stages of the ISO methodology. The proposed methodology was applied to the electrochemical hydrogenation process over nickel foam cathode where a three-case scenario (lab, worst- and best-case scenarios) was investigated to identify hotspots for early process improvement. The theoretical upscaled process had a better environmental performance compared to the lab process. The identified hotspots in the upscaled process (worst-case) include electricity process, evaporation process, and solvent recycling process for ecotoxicity (freshwater), human toxicity (cancer), human toxicity (non-cancer), climate change and resource use (minerals and metals) impact categories. The best-case scenario had its identified hotspots in the electricity process, solvent recycling process, and distillation process. This shows the importance of circularity, recycling, and lean manufacturing to the pillars of sustainability. Reducing resource consumption per unit product while increasing the recycling efficiency of process waste will be imperative towards ensuring a green chemical industry. Based on the results, a reduction of electricity demand for the process, utilisation of an alternative less energy-consuming processes, or cleaner energy sourcing could further improve the potential environmental performance of the process. Based on the quality of the data used, it is recommended that the outcome of the study be cautiously interpreted.
239

Efficient carbohydrate synthesis by controlled inversion strategies

Dong, Hai January 2006 (has links)
The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In this study it has been demonstrated that a neighboring equatorial ester group plays a highly important role in this carbohydrate epimerization reaction, 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 the ester activation effect for neighboring groups, a double parallel as well as a double serial inversion strategy was developed. / QC 20101111
240

Hur upplever ledare i gasellföretag snabb tillväxt? : En kvalitativ studie om hur ledningen på ett gasellföretag har upplevt dess företags tillväxt och interna hinder som uppstått

Bakircioglu Eriksson, Nathalie, Börjesson, Annie, Severinsson, Kim January 2022 (has links)
Att växa snabbt under en kort tid innebär utmaningar för företagets interna organisation. Snabb tillväxt betraktas mestadels som positivt och framgångsrikt, framförallt för att det bidrar till samhällets ekonomi och skapar nya jobbmöjligheter. Däremot talas det mindre om vilka utmaningar och hinder företaget bemöter under en snabb tillväxt. Snabb tillväxt i företag är till mestadels ett fenomen som lyfts fram som positivt, men det förs mindre diskussioner kring hur den interna organisationen påverkas av den snabba tillväxten. Företag som växer snabbt under en viss period kan definieras som gasellföretag. De företagen måste uppnå specifika krav gällande tillväxten uppsatta av dagens industri och kan då ansöka om att bli gaseller. Ett kriterie för att kunna klassas som gasellföretag är att företaget måste växa organiskt, vilket innebär att företaget växer inifrån och de interna delarna står för tillväxten. När de interna delarna förändras innebär det att företaget behöver fokusera på att lösa de interna hinder som kan uppstå, för att de ska kunna fortgå med tillväxten. Hinder som kan uppkomma då företaget växer snabbt rör sig vanligtvis om humankapital, kommunikation och finansiella resurser. Det är då avgörande att ledningen besitter rätt kompetenser och erfarenheter för att kunna styra företaget under tillväxten. Studien syftar till att undersöka hur ledningen på gasellföretag har upplevt dess företags snabba tillväxt och vilka hinder de bemött och behövt hantera. Sex gasellföretag har studerats och intervjuerna har genomförts med VD på respektive företag. Ledningens syn på snabb tillväxt har visats vara till den större delen positiv men samtliga har upplevt interna tillväxthinder som visat sig vara överbelastning och finansiella medel, bristande kommunikation, ofullständig strategisk planering, brist på erfarenheter bland ledning samt svårigheter att rekrytera kompetenser och motivera de anställda. Samtliga företag har valt att använda sig utav olika strategier beroende på företagets struktur, storlek och vilken typ av inställning ledaren har till den snabba organiska tillväxten.

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