We investigated the different percentage of glycerol or ethylene glycol doped into PEDOT:PSS as anode buffer layer in OSC. The electrical, optical and physical properties of PEDOT:PSS were measured before and after adding glycerol or ethylene glycol. Their optical transparency was almost the same by UV-Vis spectrophotometer. Their HOMO value, measured by PESA, was around 5.1eV. Modified PEDOT:PSS with proper concentration addition increased its conductivity. Finally, surface roughness of PEDOT:PSS layer increased with higher concentration of addition resulted in bad film-forming from spin coating process. We fabricated polymer solar cells with modified PEDOT:PSS as anode buffer layer. The devise was consisted of ITO/PEDOT:PSS (different doping concentration of glycerol or ethylene glycol ) /P3HT:PCBM /Al and measured device parameter of solar cell with sunlight simulation of AM1.5G 100mW/cm2 . We found that improvement of power conversion efficiency of polymer solar cell from 2% to 3% and short-circuit current was improved for 32%, with modified PEDOT:PSS as anode buffer layer. We suggested that the improved short-circuit current was originated from increased conductivity of PEDOT:PSS that was modified by glycerol or ethylene glycol. Finally power conversion efficiency of polymer solar cell was increased with modified.

Dialkyl carbonates are important industrial compounds that have a low toxicity and are readily biodegrade, also replacing some highly toxic and corrosive reagents in organic chemistry. There are a number of synthetic routes towards the synthesis of dialkyl carbonates, including two commercial processes (ENIChem S.p.A. and UBE Industries, LTD). The ENIChem process involves the carbonylation of methanol in the presence of CuCl2 as a catalyst. The major drawback of this process is in the use of an explosive gas mixture (CO/O2) under certain conditions. The UBE process is a two step reaction, whereby the methanol reacts with O2 and NO in the presence of a PdCl2 catalyst to form methyl nitrite and water, followed by carbonylation of methyl nitrite to form DMC and reform NO. The major drawback associated with this process is in the combination of methanol, nitric oxide and oxygen which is also explosive under some conditions. The transesterification reaction between a cyclic carbonate and an alcohol in the presence of a catalyst provide an alternative route towards synthesis of dialkyl carbonates, producing a glycol as by-product. This synthetic route is environmentally friendly, decreases explosion possibilities, and the reagents employed in this process are less hazardous than those of other processes. The main aim of this study was to identify and optimise the catalyst systems that could promote the transesterification reaction effectively. A number of homogeneous and heterogeneous, acidic or basic catalysts were evaluated during this study. The study revealed that basic homogeneous catalysts such as TBD, DBU, DBN, MTBD, DABCO, and Verkade bases are effective for the transesterification reaction. The basic heterogeneous catalysts such as Amberlites® IRA 96, IRA 67 and IRA 400 showed good catalytic behaviour, but they eventually became deactivated. On the other hand, homogeneous Lewis acids such as La(OTf)3, Gd(OTf)3, and Sm(OTf)3 demonstrated good activity, even though they need high temperatures, i.e. 150 °C. The heterogeneous acidic systems such as Amberlyst® 15, Amberlyst® 36, silica, alumina, etc., showed much lower activity, if any was observed. ix Due to the fact that these reactions were carried out above room temperature and analysed at room temperature in the GC, it was important to understand the equilibrium shift under such temperature variations, and NMR studies were used here. There was no significant difference in equilibrium conversion between the NMR reactions and the autoclave reactions (analysed in a GC), indicating slight influence of temperature variation. The results obtained from the NMR study were used to calculate the reaction kinetics. The calculations indicated a direct proportional increase of the rate with respect to the catalysts pKa values. / Prof. D.B.G. Williams

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (July 18, 2008) Includes bibliographical references.

Presented diploma thesis deals with preparation of bioresorbable polyurethanes (PUR) and their characterization. The theoretical part describes the feedstocks used for the PUR preparation and summarizes the knowledge about PUR used in medical applications. Experimental part presents characterization of bioresorbable PUR films prepared by reactive casting in one step without the use of organic solvents. The absence of solvents represents a great advantage due to their toxicity and subsequent removal from the resulting product. The synthesis of PUR was conducted under an inert atmosphere by polyaddition reaction of hydrophobic poly(e-caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) with hexamethylene diisocyanate (HDI). Synthesis under an inert atmosphere was necessary due to a side reaction of isocyanate with atmospheric humidity, which causes the formation of porous films instead of continuous ones. Prepared PUR films were characterized for different PCL/PEG ratios and different isocyanate index (ratio of NCO/OH reacted groups). PUR (isocyanate index 1.05) with PCL content 90 wt. % and higher demonstrated tought behavior in mechanical tests. Increase of isocyanate index and decrease of PCL content under 90 wt. % caused fragile sample behavior. The reason of such behavior was the different ability of PCL to crystallize in the structure of the polyurethane network. Increasing the PEG content has improved the ability of PUR films to absorb water and enhanced the rate of hydrolytic degradation. By adjusting the PCL/PEG ratio and the amount of isocyanate, solvent free bioresorbable PUR with suitable mechanical (flexibility, toughness) and physical properties (swelling, degradation) can be obtained. Prepared PUR films could be used in biomedicine e.g. as vascular grafts.

Yes / Itraconazole (ITR) is an antifungal drug with a limited bioavailability due to its poor aqueous solubility. In this study, ITR was used to investigate the impact of nanonisation and solid state change on drug’s apparent solubility and dissolution. A bottom up approach to the production of amorphous ITR nanoparticles (NPs), composed of 100% drug, with a particle diameter below 250 nm, using heat induced evaporative antisolvent nanoprecipitation (HIEAN) from acetone was developed. The NPs demonstrated improved solubility and dissolution in simulated gastrointestinal conditions when compared to amorphous ITR microparticles. NPs produced with polyethylene glycol (PEG) or its methoxylated derivative (MPEG) as a stabiliser enabled the production of smaller NPs with narrower particle size distribution and enhanced apparent solubility. MPEG stabilised NPs gave the greatest ITR supersaturation levels (up to 11.6 ± 0.5 μg/ml) in simulated gastric fluids. The stabilising polymer was in an amorphous state. Dynamic vapour sorption data indicated no solid state changes in NP samples with water vapour at 25 °C, while crystallisation was apparent at 50 °C. HIEAN proved to be an efficient method of production of amorphous ITR NPs, with or without addition of a polymeric stabiliser, with enhanced pharmaceutical properties. / Libyan Ministry of Higher Education and Scientific Research through the Libyan Embassy, London and supported by the Science Foundation Ireland under Grant No. 12/RC/2275 (Synthesis and Solid State Pharmaceuticals Centre).

The fields of tissue engineering, regenerative medicine, and stem cell engineering are rapidly growing. However, these fields must overcome several obstacles before they can make a significant impact on treating cellular disorders. Two major hurdles that must be addressed are: determining how to control the pluripotency of stem cells and developing systems for high-throughput culture of stem cells. The prospect of using a cell source capable of differentiating into cells of any tissue in the body (embryonic stem cells) has received enormous interest in recent years. The pluripotent attribute of embryonic stem cells seems ideal but developing methods to drive embryonic stem cells to specific lineages, including the hematopoietic lineage, is a complex process dependent on multiple intrinsic and extrinsic factors including chemical, cellular, and environmental signaling. With regards to environmental signaling, the use of three-dimensional culture systems such as scaffolds and hydrogels, have been utilized in an attempt to drive lineage-specific differentiation in a synthetic, biomimetic microenvironment. To determine specific environmental factors responsible for hematopoietic differentiation a systematic biological and engineering process must be implemented. A biodegradable hydrogel composed of the hyaluronic acid, a polysaccharide abundant in the bone marrow microenvironment, and the synthetic polymer, poly(ethylene glycol) was formulated to culture mouse embryonic stem cells (mESCs). Photoencapsulation of mESCs did not significantly decrease cellular viability or proliferation. The FACS data was inconclusive however, from gene expression studies, it was determined that the hydrogel culture system promoted differentiation of mESCs as evidenced by a down-regulation of the gene encoding for stem cell maintenance transcription factor, Oct-3/4. Furthermore, embryoid bodies, necessary for in vitro differentiation were observed in the hydrogel systems. Although an increase in the gene encoding for the cell surface marker, c-kit was up-regulated, the surface marker, sca-1 was not up-regulated. Up-regulation of both c-kit and sca-1 is necessary for the development of hematopoietic progenitor cells. Results indicate that the differentiation of mESCs into the hematopoietic lineage was unsuccessful but differentiation in these hydrogel systems did occur. Future cell marker and gene expression studies are necessary to determine which cell lineage the encapsulated mESCs are differentiating into before the effects of incorporating other environmental, cellular, and chemical factors can be investigated. / text

The recovery of ethylene glycol from its crude solutions in the production of polyethylene terephthalate (PET) has become important recently because of the rising cost of feedstocks for the manufacture of synthetic fibers and other polymeric materials. This work dealt with procedures for separation of ethylene glycol from its crude solutions and also with the identification of impurities, primarily phenols. The separation was carried out by fractional distillation techniques using three different additives: kerosene, hexachloronaphthalene, and naphthalene. The best additive was found by comparing the amounts of· recovered glycol. The identification of impurities was done by infrared spectroscopy and nuclear magnetic resonance spectroscopy.

A eletrooxidação de etileno glicol e de seus produtos parciais de oxidação foram estudadas em eletrodos de Pt e eletrodos binários de PtRu, utilizando-se técnicas eletroquímicas fundamentais, espectroscopia de infravermelho por reflexão externa e cromatografia líquida de alta eficiência. Os resultados evidenciam um efeito catalítico na oxidação de etileno glicol com a quantidade de Ru no eletrodo até um máximo de corrente de 11mA cm-2 entre 30% a 40% em Ru. Experimentos de espectroscopia de infravermelho in situ detectaram espécies adsorvidas, como o CO, e espécies residuais contendo dois átomos de carbono. Os produtos solúveis foram glicolaldeído, ácido glicólico e CO2. Bandas bipolares de CO indicam que o etileno glicol já está totalmente dissociado no potencial de referência (0,05 V vs. RHE). Espécies contendo o grupo carbonila como o glicolaldeído também são observadas no potencial de referência (0,05 V vs RHE). A formação de CO2 é influenciada não só pela concentração do álcool em solução como também pela quantidade superficial de Ru no eletrodo. A eletrooxidação de ácido glicólico mostra a formação de CO2 a baixos potenciais (0,20 vs. RHE) e CO adsorvido a um potencial de 0,40 V. / The eletrooxidation of ethylene glycol and its partial oxidation products, glycolic acid and glycolaldehyde was studied on Pt and PtRu electrodes. Cyclic voltammetry and chronoamperometry were used for the electrochemical characterization. The nature of the reaction products and intermediates was studied by in situ Fourier transform infrared spectroscopy and high performance liquid chromatography. The oxidation reaction is catalyzed by PtRu; the maximum current density observed was 11 μA cm-2 for a ruthenium content between 30% and 40%. Adsorbed CO and residual species containing two carbon atoms as well as CO2 glycolaldehide and glycolic acid were detected by FTIR spectroscopy. Although the quantitative determination of glycolaldehyde was not possible, the results allowed an indirect estimation of this product, which starts to be formed already at 0.05V. It was found that glycolaldehyde is the main reaction product. PtRu favors the scission of the C-C bond. Thus, much higher CO coverage was found at the alloy than at pure Pt. An increase in the amount of glycolaldehyde at PtRu indicates that this material also catalyzes the scission of the C-H bond. This effect is probably due to an electronic modification of Pt caused by the presence of ruthenium, since pure Ru is not active for adsorbing or oxidizing ethylene glycol and much less Pt sites are available at PtRu.

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-02T20:39:14Z No. of bitstreams: 1 EduardoCartonilho.pdf: 1048727 bytes, checksum: 1ab144df3ff07e53024a56b9167f9e4e (MD5) / Made available in DSpace on 2017-06-02T20:39:14Z (GMT). No. of bitstreams: 1 EduardoCartonilho.pdf: 1048727 bytes, checksum: 1ab144df3ff07e53024a56b9167f9e4e (MD5) Previous issue date: 2016-07-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) / The electroxidation of ethylene glycol and its partial oxidation products was evaluated using electrocatalysts of platinium and tin, supported on highly superficial area Vulcan XC-72 carbon. The electrocatalysts were synthesized by alcohol reduction method. Pt/C, PtSn/C 10%, PtSn/C 21% and PtSn/C 25% were characterized by Cyclic Voltammetry, Chronoamperometry, X-rays Fluorescence (XRF), X-rays Diffraction (XRD) and High Performance Liquid Chromatography (HPLC). The XRF analysis revealed that the experimental compositions of the synthesized electrocatalysts were similar to the proposed theoretical values. The results obtained by X-rays diffraction confirmed the formation of a Pt-Sn alloy. The materials revealed to have face-centered-cubic (FCC) as crystalline structure and modifications of the lattice parameters due to the addition of tin in the alloy. The electrochemical results showed a catalytic effect in the ethylene glycol oxidation. The electrocatalyst with 21wt%Sn showed a maximum current density of 4,44 x 10-5 A cm-2. The high performance liquid chromatography (HPLC) allowed to conclude that Pt/C and PtSn/C catalysts promoted the same oxidation route to produce CO2, resulting in glycolaldehyde as the main subproduct, owing to the glycolic acid formation. / A eletrooxidação de etileno glicol e de seus produtos parciais de oxidação foi estudada em eletrocatalisadores contendo platina e estanho, suportados em carbono de alta área superficial Vulcan XC-72. Os catalisadores foram sintetizados pelo método de redução por álcool. Pt/C, PtSn/C 10%, PtSn/C 21% e PtSn/C 25% foram caracterizados por Voltametria, Cronoamperometria, Fluorescência de raios-X (FRX), Difração de Raios-X (DRX) e Cromatografia liquida de alta eficiência (HPLC). As análises por FRX mostraram que as composições experimentais dos eletrocatalisadores sintetizados foram similares aos valores teóricos. Os resultados obtidos por difração de raios-X confirmou a formação da liga Pt-Sn. Os materiais apresentaram estrutura cúbica de face centrada como estrutura cristalina e modificações dos parâmetros de rede em função da adição de estanho na liga. Os resultados eletroquímicos evidenciaram um efeito catalítico na oxidação de etileno glicol. O catalisador contendo 21% de estanho (em massa) em sua composição revelou máxima densidade de corrente de 4, 44 x 10-5 A cm2. A cromatografia gasosa de alta perfomance (HPLC) permitiu concluir que os catalisadores de Pt/C e PtSn/C promoveram a mesma rota de oxidação para produzir CO2, tendo como subproduto majoritário o glicoaldeído em detrimento da formação do acido glicólico.