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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.
1271

Heck Reactions with Aryl Chlorides : Studies of Regio- and Stereoselectivity

Datta, Gopal K. January 2008 (has links)
Homogeneous palladium-catalyzed Heck vinylation of aryl chlorides was investigated under air using Herrmann’s palladacycle and the P(t-Bu)3-liberating salt [(t-Bu)3PH]BF4. Based on the results, controlled microwave heating was utilized to accelerate model Heck reactions with aryl chlorides down to 30 min employing an electron-poor olefin and a mixture of an ionic liquid and 1,4-dioxane as solvent. For the first time, a highly regioselective general protocol has been developed for palladium-catalyzed terminal (β-) arylation of acyclic vinyl ethers using inexpensive aryl chlorides as starting materials and the preligand [(t-Bu)3PH]BF4 as the key additive. This swift and straightforward protocol exploits non-inert conditions and controlled microwave heating to reduce handling and processing times, and aqueous DMF or environmentally friendly PEG-200 as the reaction medium. Somewhat higher selectivity for the linear β-product was observed in PEG-200. DFT calculations were performed at the B3LYP level of theory for the regioselectivity-determining insertion step in the Heck reaction following the neutral pathway. A series of para-substituted phenylpalladium(II) complexes was investigated in the computational study. The calculations support a ligand-driven selectivity rationale, where the electronic and steric influence of the bulky P(t-Bu)3 ligand provides improved β-selectivity. The preparative methodology was used to synthesize the β-adrenergic blocking agent Betaxolol. Highly stereoselective Pd(0)-catalyzed β-arylation and β-vinylation of a tetra-substituted cyclopentenyl ether have been accomplished using a chiral, pyrrolidine-based and substrate-bound palladium(II)-directing group under neutral reaction conditions. To the best of the author’s knowledge, this P(t-Bu)3-mediated method represents the first examples of the successful utilization of aryl and vinyl chlorides in asymmetric Heck reactions. The Heck arylation products formed were hydrolyzed and isolated as the corresponding quaternary 2-aryl-2-methyl cyclopentanones in good to moderate two-step yields with excellent stereoselectivity (90-96% ee). Inclusion of vinyl triflates under neutral reaction conditions and one aryl triflate equipped with a strongly electron-withdrawing para-cyano substituent under cationic conditions increased the preparative usefulness of the methodology. Furthermore, diastereoselective Heck arylation of both five- and six-membered cyclic vinyl ethers with aryl bromides, using the identical chiral auxiliary and suitable Pd sources, was performed. Arylated products from the tetra-substituted cyclopentenyl ether were also in this case hydrolyzed to the corresponding 2-aryl-2-methyl cyclopentanones with high to excellent enantioselectivity (85-94% ee). Despite low reaction rates and relatively modest yields, arylation reactions with the tri-substituted cyclohexenyl ether were found to be highly diastereoselective (94-98% de). Thus, an attractive supplement to direct Pd(0)-catalyzed α-arylation protocols, particularly when the use of organic chlorides, aryl bromides, and milder reaction conditions are of great importance, have been developed.
1272

Validation of Abbott Diagnostics turbidimetric cystatin C assay and enzymatic creatinine assay using the Architect c8000 analyzer

Dehmer, Susanne January 2009 (has links)
Objective: Estimation of glomerular filtration rate (GFR) is an important tool in the diagnosis and management of chronic kidney disease. Today creatinine is the most frequently used marker for kidney function though several studies indicate that cystatin C is a superior marker. The purpose of this study was to validate Abbott Diagnostics turbidimetric cystatin C assay and enzymatic creatinine assay. Methods: The validation was performed by studies of CV for the two methods and correlations between the two and other available methods for assessing GFR. The stability of cystatin C at room temperature was also evaluated. Results: Both methods showed good precision. The Abbott cystatin C assay generally gave lower values and thereby higher estimated GFRs than the correlated Gentian method. The Abbott enzymatic creatinine assay gave higher values than the correlated Jaffe method. Those results are generally unexpected, but in this study the cause is an automatically applied negative intercept used together with the Jaffe method. Cystatin C showed high stability when stored at room temperature. Conclusions: Estimated GFRs tend to differ depending on the choice of method for analyzing cystatin C or creatinine and this study gives an overview of the range of variation. The study also enlightens the need for an international calibrator for the cystatin C methods presented by different manufacturers.
1273

TaqMan® Sample-to-SNP Kit™ : evaluation of kit for low-cost and fast preparing of DNA-samples before genotype analysis

Andersson, Eva January 2009 (has links)
Genotyping can be used to link genetic variation among individuals to certain diseases or conditions. Some known disorders and states that are dependent on single nucleotide polymorphism (SNPs) are lactose intolerance, venous thrombosis, hereditary hemochromatosis and the difference in sensibility among people to metabolise drugs. In this project a new kit, TaqManÒ Sample-to-SNP KitÔ for extraction of DNA and preparation of the extract for genotyping with real-time PCR and allelic discrimination, was evaluated. QIAamp® DNA Blood Biorobot® MDx Kit was used as the reference method. The purpose of the comparison was to find a method that makes DNA extraction from blood samples cheaper and faster, but with the same reliability as the reference procedure. The results of the evaluation showed a complete agreement of the genotype results between the methods tested, which means that the new method was as reliable as the reference method. The costs of reagents and material would be reduced with 52% if the new method is adopted, that alone would result in a cost reduction of 144 000SEK a year with a sample volume of 650 samples/month. The time for DNA extraction would also be reduced with the new procedure.
1274

Determination of testosterone esters in serum by liquid chromatography – tandem mass spectrometry (LC-MS-MS)

Törnvall, Erica January 2010 (has links)
Anabolic androgenic steroids are testosterone and its derivates. Testosterone is the most important naturally existing sex hormone for men and is used for its anabolic effects providing increased muscle mass. Testosterone is taken orally or by intramuscular injection in its ester form and are available illegally in different forms of esters. Anabolic androgenic steroids are today analyzed only in urine. To differentiate between the human natural testosterone and exogenous supply the quote natural testosterone and epitestosterone is used. Detection of testosterone esters in serum is an unmistakable proof of exogenous supply of testosterone. The aim of this thesis was to find a method for determining testosterone esters in serum and to study an extraction method possible for quantification of testosterone esters in serum. The technique used to separate and identify the Testosterone esters was Liquid Chromatography Tandem Mass Spectrometry Electro Spray Ionisation. Parameters for chromatography and mass detection were optimized for nine testosterone esters and evaluated according to selectivity, resolution and intensity. A method that could be used for determination of testosterone esters in serum was found. The MS-method was set and at least three possible transitions for each testosterone ester were found. The best choice of column proved to be the C18 column where all the esters were separated and seven of them were base-line separated. The C18 column along with methanol and ammonium acetate buffer, 5 mM, pH 5 showed the highest sensitivity for Multiple Reaction Monitoring-detection. A gradient profile for a total runtime of 5.6 minutes was established. Two alternative extraction procedures were tested, with tert-butylmethylether or diethyl ether/ethyl acetate and both seemed to work satisfactory. Analysis of serum proved to work well and no severe interference occurred. Results from the linearity tests indicate that future quantification method in serum will be possible.
1275

Affinity capillary electrophoresis of Beta-2-glycoprotein I and Anionic phospholipids

Olsson, Ola January 2010 (has links)
No description available.
1276

Development of a Method for Measuring Pasta Quality Parameters

Haraldsson, Jörgen January 2010 (has links)
In this work the objective was to develop a method that would make it easier to quantitatively evaluate different quality parameters in pasta. This was done with the assistant of a texture analyzer from TexVol Instruments. The quality parameters that were investigated were hardness, resilience, elasticity and adhesiveness. Two different types of measurements were used to measure three different pasta brands. These were single cycle and hold until time. Before this was done the main parameters in the texture analyzer were tested and adjusted to suite the method. Most of the steps in the developed method worked satisfactorily but more studies have to be done to make the method useful in the daily work with pasta production and pasta development. With all tests in mind it could be said that the De Cecco pasta was the one with the best texture parameters. It had the highest hardness, elasticity and resilience and the lowest adhesiveness. The other two brands, Kungsörnen and Tomadini had lower but similar results. Further important studies to look into is if there`s a possibility to get a computer software that are more targeted on pasta measurement. Another important thing is if these pasta measurements can be done in a different way, perhaps just using a few spaghetti straws. It would also be interesting to study the protein network in an electron microscope because then it´s easier to understand what´s happening when pasta is prepared. Last but not least I think it´s important to do a organoleptic test to see if it´s possible to taste the measured results. / Detta examensarbete gick ut på att ta fram en metod med hjälp av en texturmätare där olika kvalitetsparametrar såsom hårdhet, elasticitet och spänst kunde mätas på pasta. Dessa mätningar gjordes på tre olika spaghettimärken. Dessa var Kungsörnen, Tomadini samt De Cecco. Mätningarna på de olika pastamärkena gjordes med hjälp av en texturmätare från TexVol som är ett svenskt företag. Deras olika instrument är främst framtagna för att fungera inom bageribranchen och köttindustrin. Detta gjorde att det var spännande att se om detta instrument även kunde användas med framgång för att mäta olika kvalitetsegenskaper på kokt pasta. Först gjordes mätningar på Kungsörnens spaghetti vid olika koktider. Dessa var mellan 5 och 14 minuter. Dessa mätningar gjordes främst för att se vad som händer med de olika kvalitetsegenskaperna från det att pastan är underkokt till kraftigt överkokt. Utifrån resultaten från dessa mätningar är det svårt att dra några tydliga slutsatser då de varierade kraftigt. Därefter gjordes mätningar på de tre olika pastamärkena med två olika mätmetoder, dels single cycle och dels hold until time. Med single cycle menas att proben(mätstången) går ner i pastan och sen direkt upp igen medan vid hold until time metoden så går proben ner för att sen stanna nere tills en förinställd tid passerat innan den går upp igen. På detta sätt kan olika kvalitetsegenskaper mätas med de olika mätmetoderna. För att dessa mätmetoder ska fungerar har olika parametrar på texturmätaren utvärderats och på detta sätt har en metod/tillvägagångssätt tagits fram. De flesta av stegen i denna metod verkar fungera bra men ett stort problem är att mätningarna skiljer sig mycket åt. Detta beror troligtvis på att pastan lägger sig olika inför varje mätning vilket gör att mätningarna blir långt ifrån identiska vilket leder till att resultaten blir svårtolkade. Vissa tendenser kan dock ändå ses. Om alla mätningar tags i beaktande kan det sägas att De Cecco pastan är den pasta av högst kvalité. De Cecco pastan är den som är mest "al dente", mest elastisk, mest spänst samt lägst klibbighet. Vad detta beror på är svårt att säga då det kan finnas många förklaringar som är mer eller mindre relevanta. En trolig förklaring kan vara att De Cecco pastan har ett högre proteininnehåll än de båda andra märkena. I litteraturen står det att ett högre proteininnehåll ger en bättre kokt pasta och detta verkar rimligt då protein nätverket blir starkare vilket håller ihop pastan på ett bättre sätt. En annan möjlig orsak kan vara att fördelningen av de olika proteinerna är bättre i De Cecco pastan än i de andra märkena vilket leder till en bättre kvalitet. De två andra, Kungsörnen och Tomadini hade snarlika resultat. Vad som behöver göras för att denna metod eventuellt ska kunna användas i den dagliga produktionen av pasta och utveckling av ny pasta är att ta bort så många felkällor som möjligt så att standardavvikelsen i alla mätningar blir avsevärt mindre. Detta kan kanske avhjälpas av att ha en mjukvara som är mer anpassad till pastamätningar än den som var används nu som är anpassad till bageribranchen. En annan viktig sak kan vara att mäta på bara några få pasta strå till skillnad mot nuvarande "spaghettinystan". Ytterligare en intressant sak är att göra en organoleptisk undersökning av de olika pastamärkena för att se om de uppmätta resultaten är smakbara. Även att titta i elektronmikroskåp för att se de olika spaghettis proteinnätverk kan vara intressant för att få en förståelse för hur pastan ändrar sig under kokning.
1277

Excitation transfer between conjugated polyelectrolytes and triplet emitter confined in protein nanowires

Thinprakong, Chorpure January 2010 (has links)
Phosphorescent metal complexes can be incorporated into amyloid-like fibrils, and these fibrils can be decorated with conjugated polyelectrolytes (CPEs). In this study, fac-tris[2-phenylpyridinato-C2,N]irdium(III) complexes [Ir(piq)3] were used as the phosphorescence emitter and Sodium-poly(3-thiophene acetic acid) (PTAA-Na) compounds were used as CPEs. Herein we study the energy transfer processes between the iridium complexes and the CPEs. To investigate these mechanisms, the analysis of the emission quenching and time-resolved measurements were done. Our measurements show that energy can be transfered from singlet state of PTAA to the singlet state of Ir(piq)3. Moreover, incorporation of iridium into amyloid fibrils decreases the importance of energy transfer by the Dexter mechanism. Finally we propose a geometry of interaction to explain the obtained results.
1278

Development of a quantitative chromatographic method for the determination of Imatinib and its main metabolite in human plasma

Hillberg, Paulina January 2009 (has links)
The objective of this master thesis was to develop an analytical method for the quantification of the cancer drug Imatinib and its main metabolite CGP74588 in plasma. Imatinib is used in the treatment of chronic myeloid leukemia and gastrointestinal stroma tumors. A quantitative analytical method was developed where reversed-phase columns with different stationary phases were studied and the sensitivity was tested with both UV detectors and a mass spectrometric detection. Since the substances were measured in plasma a solid-phase extraction was developed to purify the samples before analysis. The column chosen for the separation was the Max-RP C12 column (100 x 3 mm, 4 μm particle size) manufactured by Phenomenex with a gradient mobile phase with 1% formic acid in methanol and water. The gradient was as follows; 0 min 15:85, 7 min 60:40, 9 min 60:40 with a total runtime of 13.5 min. The internal standard chosen was Opipramol. Mass spectrometric detection using a sonic spray ionization interface in positive mode proved to be about as sensitive as UV detection at 261 nm. The generated (M+H+)+ ions were isolated and fragmented with the use of three mass spectrometric methods; one for Imatinib (transition 494 —› 394), one for CGP74588 (transition 480 —› 394) and one for Opipramol (transition 364 —› 171). For the purification of the plasma samples an Oasis HLB solid-phase extraction cartridge was selected and the recoveries were close to 100%. The developed method was partially validated and showed coefficients of variation (CV) for intra-and inter-day precision between 0.4 and 5.4% with UV detection. The validation results for the mass spectrometer were inconclusive.
1279

Surfactants in anionic latex films

Paakkonen, Johan January 2010 (has links)
No description available.
1280

Protein i korn : En torkstudie utförd med etablerade analysmetoder på tre kornsorter / Protein in barley - A drying study performed with established analytical methods on three varieties of barley

Broberg, Mikael January 2010 (has links)
A study was performed to evaluate whether established methods of analysis of protein content in barley (Kjeldahl, Dumas, or NIT (short for Near Infrared Transmittance)) gives different results for wet and dried barley. This was carried out because there are concerns regarding the well-worn NIT prediction model giving different results for these conditions and that such an error causes significant price fluctuations on the market. By performing analyses of samples, both before and after drying, of the three different barley varieties Tipple, Prestige, and Quench, with all the techniques, data was obtained that could be analyzed statistically. The study showed that the NIT prediction model gives results for wet barley that is about 0.29 percentage points higher compared to dried barley. This difference was also statistically significant when a t-test was performed. The same difference was substantially smaller for Kjeldahl and Dumas and furthermore not statistically significant. When the difference between the different barley varieties is studied a deviation of 0.34 percentage points was obtained for Tipple, 0.18 percentage points for Prestige, and 0.30 percentage points for Quench. NIT, thereby, gave results with greatest deviation when wet Tipple was analyzed. When t-tests were performed for each barley variety, it was found that results for all varieties differ significantly between wet and dry barley. A study of the difference between the crude protein content determination by Kjeldahl and Dumas was also performed by calculating the mean differences between the various methods of determination. The average difference in crude protein determination was calculated to 0.07 percentage points.

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