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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.
221

DNA chips with conjugated polyelectrolytes as fluorophore in fluorescence amplification mode

Magnusson, Karin January 2008 (has links)
The aim of this diploma work is to improve selectivity and sensitivity in DNA-chips by utilizing fluorescence resonance energy transfer (FRET) between conjugated polyelectrolytes (CPEs) and fluorophores. Leclerc and co-workers have presented successful results from studies of super FRET between fluorophore tagged DNA and a CPE during hybridisation of the double strand. Orwar and co-workers have constructed a DNA-chip using standard photo lithography creating a pattern of the hydrophobic photoresist SU-8 and cholesterol tagged DNA (chol-DNA). This diploma work will combine and modify these two ideas to fabricate a improved DNA-chip. Immobilizing of DNA onto surface has been done by using soft lithography. Hydrophobic pattern arises from the poly(dimethylsiloxane) (PDMS) stamp. The hydrophobic pattern will attract chol-DNA that is adsorbed to the chip. Different sets of fluorophores are covalently bound to the DNA and adding CPEs to the complex will make FRET occur between CPE and bound fluorophore. We will here show that the specificity in DNA hybridization by using PDMS patterning was high. FRET clearly occurred, especially with the CPEs as donor to the fluorophore Cy5. The intensity of FRET was higher when the fluorophore and the CPE were conjugated to the same DNA strand. The largest difference in FRET intensity between double stranded and single stranded complexes was observed with the CPE tPOMT. Super FRET has been observed but not yet fully proved. The FRET efficiency was lower with the fluorophore Alexa350 as donor compared to the Cy5/CPE complex. Most of the energy transferred from Alexa350 was extinguished by quenching.
222

A Molecularly Switchable Polymer-Based Diode / En Molekylärt Switchbar Polymerbaserad Diod

Hultell Andersson, Magnus S. January 2002 (has links)
Despite tremendous achievements, the field of conjugated polymers is still in its infancy, mimicking the more mature inorganic, i.e. silicon-based, technologies. We may though look forward to the realisation of electronic and electrochemical devices with exotic designs and device applications, as our knowledge about the fundamentals of these promising materials grow ever stronger. My own contribution to this development, originating from an idea first put forward by my tutor, Professor Magnus Berggren, is a design for a switchable polymer-based diode. Its architecture is based on a modified version of a recently developed highly-rectifying diode,12 where an intermediate molecular layer has been incorporated in the bottom contact. Due to its unique ability to switch its internal resistance during operation, this thin layer can be used to shift the amount of (forward) current induced into the rectifying structure of the device, and by doing so shift its electrical characteristics between an insulating and a rectifying behaviour (as illustrated below). Such a component should be of great commercial interest in display technologies since it would, at least hypothetically, be able to replace the transistors presently used to address the individual matrix elements. However, although fairly simple in theory, it proved to be quite the challenge to fabricate the device structure. Machinery errors and contact problems aside, several process routes needed to be evaluated and only a small fraction of the batches were successful. In fact, it was not until the very last day that I detected the first indications that the concept might actually work. Hence, several modifications might still be necessary to undertake in order to get the device to work properly.
223

Conjugated linoleic acid combined with creatine monohydrate and whey protein supplementation during strength training

Jantz, Nathan Timothy 28 January 2010 (has links)
The purpose of this thesis was to determine the combined effects of protein, creatine, and conjugated linoleic acid (CLA) supplementation during resistance training. These nutritional supplements are popular during resistance training and we wanted to determine if they would have additive effects for improving body composition and strength. Forty-four participants (32 males, 12 females, mean age 20y) were randomized into three groups to receive: 1) 36 g/d protein (PRO), 2) protein and 9 g/d creatine (PRO/CR), or 3) protein, creatine and 6 g/d CLA (PRO/CR/CLA) for 5 weeks while resistance training on a four-day cycle (three days of resistance training, followed by one day of rest). Measurements at pre- and post-testing included body composition, muscle thickness of the elbow and knee flexors and extensors, and bench and leg press strength. There were time main effects (p<0.01) for strength, and muscle thickness. The PRO/CR/CLA group had significant increases in knee extensor muscle thickness over time compared to the other groups (p<0.05). There were no other differences between groups over time. The combinations of creatine and protein, or creatine, protein and CLA had no effects on body composition. It is concluded that combining protein, creatine, and CLA has minimal effects on muscular strength, muscle thickness, and body composition.
224

Studies of Inverted Organic Solar Cells Fabricated by Doctor Blading Technique

Tang, Zheng January 2010 (has links)
Over the last few decades, bulk-heterojunction organic photovoltaic devices comprising an intimately mixed donor-acceptor blend have gained serious attention due to their potential for being cheap, light weight, flexible and environmentally friendly. In this thesis, APFO-3/PCBM bulk-heterojunction based organic photovoltaic devices with an inverted layer sequence were investigated systematically. Doctor blade coating is a technique that is roll-to-roll compatible and cost efficient and has been used to fabricate the solar cells. Initial studies focused on optimization of the electrodes. A thin film of the conductive polymer PEDOT:PSS was chosen to be the transparent anode. Different PEDOT:PSS films with respect to the film thickness and deposition temperature were characterized in terms of conductivity and transmission. Decent conductance and transmittance were obtained in the films deposited with wet film thickness setting of 35 μm, The cathode was fabricated from a metal bilayer comprising Al and Ti with an area about 1 cm2, and the best-working cathodes contained a 70 nm thick Al layer covered by a thin Ti layer of about 10 -15 nm. Optimized coating temperature and wet film thickness settings for the active layer and PEDOT:PSS layer were experimentally determined. The highest efficiency of the APFO-3/PCBM based inverted solar cells fabricated by doctor blading was 0.69%, which exceeded the efficiency of spin-coated inverted cells. A higher efficiency (0.8 %) was achieved by adding a small amount of high molecular weight polystyrene to the active layer. Morphological changes after adding of the polystyrene were observed by optical microscopy and AFM. A coating temperature dependent phase separation of the APFO-3/PCBM/polystyrene blend was found.
225

Polymer Electrochromism on PEDOT coated fibres and design of electrochromic pixel using coated fibres.

Lakshmanan, Nethaji, Rangasamy, Logarasu January 2008 (has links)
Polymer electrochromism on PEDOT coated fibres was successfully achieved. The electrochromic property of the PEDOT polymer is an excellent property. This feature gives way to many more research works at present and in the future also. The electrochromic property of the PEDOT polymer is utilized in this thesis work to design an electrochromic display pixel. The polymer coating over the fibres were obtained by using In-situ polymerization technique. The coated-fibres were used to design a display-pixel. Electrochemistry is performed successfully on the designed pixel to study electrochromism over the pixels. An electrochemical fibre transistor is designed successfully using the polymer coated fibres. / Polymer Electrochromism on PEDOT coated fibres
226

Phenyleneethynylenes: Structure, Morphology and Photophysical Properties of Novel Pi Systems

Wilson, James Norbert 02 December 2004 (has links)
The syntheses of novel poly(paraphenyleneethynylene)s, PPEs, and poly(aryleneeethynylene)s, PAEs, as well as hybrid poly(paraphenyleneethynylene)- poly(paraphenylenevinylene)s, PPE-PPVs, are presented. Fluorescent PPEs decorated with biologically relevant ligands are utilized in model biosensing schemes. PPE-PPV hybrids, as well as their highly emissive oligomeric, cruciform model compounds are studied in an effort to modify the bandgap of the parent PPE backbone. Improved hole and electron injection capabilities are demonstrated with these hybrid conjugated materials. Structural variation and morphological effects of PPEs, PPE-PPVs and model compounds are studied to elucidate the effects upon the photophysical properties of the emissive materials.
227

Grafted and Crosslinkable Polyphenyleneethynylene: Synthesis, Properties and Their Application

Wang, Yiqing 28 November 2005 (has links)
This thesis presents the first reported grafted PPE - polycaprolactone-g-PPE; the first PPE based sensing model: biotinylated grafted PPE/streptavidin coated sphere; the first photocrosslinkable PPE ¨C allyloxy PPE; and the new mechanism which demonstrates morphology control on a single molecular level
228

Electroluminescence of Layer Thickness, Carbon Nano-particle Dopants, and Percolation Threshold Electric Conductivity of Fully Conjugated Rigid-rod Polymer

Chang, Chih-hao 02 July 2010 (has links)
Polymer light emitting diodes (PLED) were using a heterocyclic aromatic rigid-rod polymer poly-p-phenylene-benzobisoxazole (PBO) as an opto-electronically active layer; and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) as a hole transporting layer. Aluminum (Al) and indium tin oxide (ITO) were served as device cathode and anode, respectively. [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) or derivatized multi-wall carbon nano-tube (MWCNT-C18), with great electron transporting ability, was doped into PBO to enhance the performance of PLED devices as well as the thin-film electrical conductivity. The optical length was changed by using different spin coating speeds and durations. From the research, the £fmax of electroluminescence (EL) was blue-shifted as PEDOT:PSS spin coating speed increased for a thinner layer. Once using a higher spin coating speed repeatedly to coat PEDOT:PSS, the £fmax of electroluminescence was red-shifted. If the PEDOT:PSS film thicknesses were similar, the EL spectra were almost the same, independent of device processing scheme. The injection current and EL intensity were enhanced by doping PC61BM or MWCNT- C18. The electric conductivity parallel to film surface (£m¡ü) was increased as the doping concentration increased. Because of the extremely different aspect ratio, the MWCNT-C18 had a lower percolation threshold concentration. Therefore, at a low MWCNT-C18 doping concentration, the injection current and the EL intensity were enhanced compared with those of PC61BM.
229

Effect of Conjugated Linoleic Acid or Oleic Acid Addition on Fatty Acid Composition Profiles of Poultry Meat

Shin, Dae Keun 2010 May 1900 (has links)
Two different studies were conducted to reduce the overall amount of omega-6 fatty acids in broiler chickens. The first experiment was performed to determine the effects of dietary conjugated linoleic acid (CLA) and omega-3 fatty acid combination on the omega-6 fatty acid accumulation in broiler chicken breast and thigh meat. Eight broilers from each treatment were processed at 4 and 6 weeks of age, respectively. Regarding the diets containing five different fat sources, broiler chickens fed CLA and fish oil diet had a lower C20:4 (arachidonic acid, AA, n-6) deposition but showed a higher n-3/n-6 ratio in breast and thigh meat than those fed a flaxseed oil diet and CLA and flaxseed oil diet (P < 0.05). The C20:4 and n-3/n-6 ratio of breast and thigh samples from fish oil diet was similar to those of the conjugated linoleic acid and fish oil combination diet (P > 0.05). However, the addition of CLA and fish oil to the diet resulted in a increase of polyunsaturated fatty acid (PUFA) concentration in broiler chicken breast and thigh meat when compared to that of fish oil diet (P<0.05). The second experiment was conducted based on six different combination of n-3 and n-9 fatty acids. One bird per pen was processed, and each bird was weighed, and blood, liver, breast and thigh samples from the bird were collected. Although the generation of prostaglandin E2 (PGE2) was not affected due to combination of n-3 and n-9 fatty acids in our diets, the deposition of n-6 fatty acids including C18:2 and C20:4 was decreased in broiler chicken breast and/or thigh muscles as n-3 fatty acids were supplied to broiler chickens for 9 weeks. Eicosapentaenoic acid (C20:5, EPA, n-3) addition to poultry diet (FEO) did not reduce the deposition of C18:2 and/or C20:4 as much as C22:6 (FDO) did. When C20:5 and C22:6 were blended to poultry diet (FHO) and fed to broiler chickens for 9 weeks, synergistic effects were observed. Reduction of C20:4 was obtained when FHO diet was fed to broiler chickens, and it may be induced due to decreased expression of delta-6 desaturase mRNA.
230

Lipid Metabolism, Gene Expression, Substrate Oxidation, and Meat Quality of Growing-finishing Pigs Supplemented with Conjugated Linoleic Acid and Arginine

Go, Gwang-Woong, 1979- 2010 December 1900 (has links)
We hypothesized that supplementation of dietary conjugated linoleic acid (CLA) and arginine singly or in combination would increase animal performance and meat quality by decreasing adiposity and increasing lean mass in growing-finishing pigs. Sixteen pigs (80 kg) were assigned to four treatments in a 2 x 2 factorial design, differing in dietary fatty acid and amino acid composition [control: 2.05% alanine (isonitrogenous control) plus 1% canola oil (lipid control); CLA: 2.05% alanine + 1% CLA; arginine: 1% arginine + 1% canola oil; arginine + CLA: 1% arginine + 1 CLA]. Preliminary tests indicated that up to 2% arginine was acceptable without interfering with lysine absorption. Pigs were allowed to feed free choice until reaching 110 kg. There were no significant differences across treatments in feed intake, weight gain, or feed efficiency. CLA tended to decrease carcass length (P = 0.06), whereas backfat thickness tended to be greater in pigs supplemented with arginine (P = 0.08). Arginine decreased muscle pH at 45 min postmortem (P = 0.001) and tended to increase lightness of muscle at 24 h postmortem (P = 0.07). CLA supplementation increased the concentrations of trans-isomers of 18:1 (P = 0.001) and SFA (P = 0.01) in s.c. and r.p. adipose tissue. CLA supplementation increased palmitate incorporation into total lipids in longissimus muscle (P = 0.01). Glucose oxidation to CO₂ in r.p. and s.c. adipose tissue were greater in pigs supplemented with CLA in the absence or presence of arginine (P = 0.03 and P = 0.04, respectively). The volume of s.c. adipocytes in s.c. and r.p. adipose tissues was greater in pigs supplemented with CLA, arginine, or CLA plus arginine than in control pigs (P = 0.001). Neither CLA nor arginine affected the expression of PGC-1[alpha],AMPK, mTOR, CPT-1A, FAS, or SCD (P > 0.05) in any tissues. We conclude that there was no significant interaction between arginine and CLA. Supplementary CLA or arginine to finishing-growing pigs did not modulate growth performance and did not reduce adiposity. CLA increased intramuscular fat content without deteriorating meat quality traits and increased saturated fatty acids and substrate oxidation in adipose tissues. In the presence of 1% of canola oil or CLA in the diet, arginine has the potential to deteriorate meat quality by reducing early postmortem pH and by increasing carcass fatness.

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