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1
Al-Harbi, Nasser Munawir D. "Characterisation of complex polymer mixtures." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-of-complex-polymer-mixtures(be0269fe-2ac3-4128-ba57-4a03dbf46a7e).html.
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The polymer of intrinsic microporosity PIM-1 was synthesized following various procedures: (i) from fluoro-monomer by the conventional method, (ii) from fluoro-monomer by a high temperature, high shear mixing method and (iii) from chloro-monomer. For a more complete understanding of the structure of the resultant products of a series of polymerizations under different reaction conditions, a multi-detector gel permeation chromatography (GPC) method was established and validated. A procedure for fractionating PIM-1 using chloroform methanol solvent mixtures was established and validated. A combination of multi-detector GPC and matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) masss pectrometry was used for the determination of molar mass distribution and to identify structural differences between fractions and between the products from different synthetic procedures. High molar mass samples tended to have broader molar mass distributions. Both Mark-Houwink plots and hydrodynamic volume plots showed deviation from linearity at Mw= 200000 g mol-1, which was attributed to branching. A low cost route for the preparation of PIM-1 from chloro-monomer was successfully established, though samples prepared by this route had broader polydispersities than those prepared from fluoro-monomers. It was found that stable flexible membranes were formed from samples with Mw > 83000 g mol -1. In addition, a comparison of two analytical methods for extraction and determination of additives in HDPE, LLDPE and PP polymers of interest to Saudi Basic Industries Corporation was performed. A comparison of dissolution with ultrasonic assisted extraction methods for the determination of anti-oxidant additives in polyolefins was performed. Ultrasound assisted extraction methods were found to be superior for HDPE and LLDPE, where conventional dissolution was preferred for PP.
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Stehlík, Pavel. "Stanovení vybraných strobilurinových pesticidů v ječmeni, sladu a pivu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216412.
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This diploma work is aimed determination of strobilurine pesticide in barly, malt and berr. Identifikation of strobilurine was made according to mass spectra library and base of commercialy standard. The next quantifikation in samples was made. The work consist of three main parts refer about problems. In therotical part is the method of plant, grown protection. This part is about pesticides and their fission, history and effects. In experimental part is method for determination strobilurine. In part results and discussion are all result and data in tables a graphs. At the end is sumed up result this work.
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Gustavsson, Per-Erik. "Superporous agarose a new material for chromatography /." Lund : University of Lund, 1998. http://books.google.com/books?id=ButqAAAAMAAJ.
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Li, Zhiguo. "High-performance liquid chromatography analysis of fatty acids and mathematical modeling of liquid chromatography." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1179157379.
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Chen, Yu-Jen. "The solubility enhancement and the stability assessment of rifampicin, isoniazid and pyrazinamide in aqueous media." Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1005009.
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Tuberculosis (TB) is a highly contagious disease caused by the bacterium known as Mycobacterium tuberculosis which is widely spread in South Africa, especially in the rural areas of the Western Province. Rifampicin, isoniazid and pyrazinamide are the three most effective drugs against this organism. However, most of the current commercial anti-TB formulations are inconvenient to administrate. This results in patient non-compliance which has increased with incomplete tuberculosis treatment and further has intensified the mortality rate. The matter is especially severe amongst the paediatric and geriatric patients. Therefore, creating a "user-friendly" but non-alcoholic liquid formulation should improve the whole situation. The key to a successful formulation relies on sufficient concentrations of the drugs within the formulation together with acceptable stability of these drugs. Therefore, during the pre-formulation stage, the solubility and stability studies of rifampicin, isoniazid and pyrazinamide are to be conducted. Rifampicin, isoniazid and pyrazinamide were fully characterized and identified by means of spectroscopic and thermal techniques. A HPLC method for simultaneous analysis of the three drugs was developed and validated. This HPLC method was employed for all the solubility and stability assessments. Unbuffered HPLC water of pH value 7.01 was chosen as the aqueous solvent. This was decided after the stability of rifampicin, isoniazid and pyrazinamide was studied at a pH range of 2 to 10. The solubility and the stability studies of rifampicin, isoniazid, pyrazinamide, rifampicin with isoniazid, rifampicin with pyrazinamide, isoniazid with pyrazinamide and rifampicin combined with both isoniazid and pyrazinamide were performed in the presence of various agents. These agents can be categorized into three groups: the surfactants (poloxamer 188, poloxamer 407 and sorbitol) which could increase the intrinsic solubility or the drugs by altering the surface tensions of the aqueous solution medium, the suspending agents (carbopol 934 and carbopol 974P) which could enable the amount of dosage required to be homogeneously suspended in the formulation without considering the low intrinsic solubility factor of the drugs, and the complexing agents (ß-cyclodextrin, hydroxypropyl-ß-cyclodextrin and -cyclodextrin) which could initiated the inclusion complex between the host cyclodextrin and the drugs, thus further enhance the solubility of the drugs . The stability assessments were performed after 7-days stability trail with the HPLC method developed. Each drug/combination of drugs were stored in closed ampoules and subjected to 25, 40 and 60° C with or without nitrogen flushing while in the presence of the above mentioned agents. While assessing the solubility/stability of the drugs in the presence of the above mentioned surfactants, the phase-solubility curves indicate that both rifampicin and pyrazinamide fail to achieve the desired concentration. Moreover, the stability-time plots clearly indicate that these surfactants fail to enhance the general stabilities of the drugs. When the stabilizing effects of the above mentioned suspending agents were investigated, it was found that although the desired concentration could be easily accomplished by suspending the drug in the aqueous carbopol solutions, the stabilities of the different drug combinations were still below the regulatory level. Cyclodextrins are well known to form inclusion complexes with less polar drug molecules. The inclusion complexation could enhance both the solubility and the stability of the included drug molecules. The computer force field generated models of the cyclodextrin-drug were used to predict the complexation sites. The results indicated the all the inclusion complexation between the drugs and the cyclodextrins were favourable, but do not necessary protect the potential degradation sites of the drugs. The stability results confirmed the above findings as the cyclodextrins did not enhance the stability of the drugs. Various drug-drug interaction pathways were also predicted from the experimental observations which clearly indicated the stability reductions of these drugs in combination. This leads to the conclusion that a liquid formulation combining rifampicin, isoniazid and pyrazinamide should not initiate the use of aqueous solutions as the protic ions of the solution are able to initiate the degradation of these drugs.
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Miller, Keith Edward. "Dynamic surface tension detector in flow injection analysis and liquid chromatography /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8506.
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Ring, Ludwig. "Purification of psychoactive biomolecules in plants using size exclusion chromatography." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-18434.
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Size exclusion chromatography (SEC) was applied for purification of psychoactive biomolecules from plants. These molecules are in the same molecular weight range, but do not necessarily share other chemical properties, that makes the SEC technique efficient. By applying SEC as a first purification step much of the co-extractives from the plants can easily be removed. Large amounts of target substance can be obtained with little effort if the system is automated. Combining SEC with a second purification step, consisting of normal phase chromatography, provides high purity of the target substance.
Both known and unknown psychoactive biomolecules can easily be purified using the purification method developed in this Master's Thesis. Purifications that previously required long time and much "hands-on" can be completed much faster and with less manual work.
The method developed was tested on cannabis, coffee and 'Spice' with good results.
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Thomas, Sydney. "Measurement and modelling of long chain branching in chain growth polymerization." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/NQ42769.pdf.
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Heldreth, Lori G. "The evaluation of crosslinked poly-4-vinylpyridine as a packing material for size exclusion chromatography." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/44471.
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Crosslinked poly-4-vinylpyridine (XPVP) has not previously been used as a size exclusion chromatographic packing material. This material appears attractive for the analysis of nitrogen containing polymers because of its basic nitrogen functionality, and desirable physical properties. Its use as such is investigated with probe compounds in several different mobile phases. Various methods of separation of the XPVP material by particle size are employed. In addition, four column packing techniques were examined.Master of Science
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Braddy, April C. "Increased-throughput screening of potential drug candidates for permeation across membranes and estimation of central nervous system bioavailability." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0008420.
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Thesis (Ph.D.)--University of Florida, 2004.Typescript. Title from title page of source document. Document formatted into pages; contains 167 pages. Includes Vita. Includes bibliographical references.
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Sousa, Anayla dos Santos. "Gel permeation chromatography in semi-preparative scale apply to the characterization, purification and fractionation of microbial hyaluronic acid." Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2410.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorHyaluronic acid (HA) is a linear, unbranched polymer, composed by simple disaccharide units, whose molar mass may range in a wide interval of distribution (104-107 Da). It is used in pharmaceutical and cosmetic applications depending on its average molecular mass. The fractionation of macromolecules of the order of magnitude of the HA may be performed by gel permeation or size-exclusion chromatography (GPC). The objective of this work is to study the characterization, purification and fractionation of microbial HA by using GPC. HA was supplied by the Department of Biotechnological Processes (DPB/FEQ/UNICAMP), having been produced by microorganisms â Streptococcus zooepidemicus â in synthetic culture media. After being centrifuged from the fermentation broth, HA was precipitated with ethanol and then dissolved in saline solution, this pre-purification procedure being performed up to four times. The presence of proteic contaminants was identified by electrophoresis in polyacrylamide gel under denaturant conditions (SDS-PAGE) and quantified by the Bradford method. For the HA sample which had been precipitated in ethanol and dissolved in 0.1 M NaNO3 four times, protein concentration was found to be nearly 100 μg/mL. The sodium salt of commercial (Sigma Aldrich - EUA) microbial HA was used as standard in order to measure a calibration curve to assess HA concentration in the samples. For the sample precipitated in ethanol and dissolved in 0.1 M NaNO3 four times, AH concentration was found to be approximately 780 μg/mL. Molar mass distribution of HA samples was assessed by GPC, both in analytical and semi-preparative scale, using refractive index (RI) and UV/Vis (280 nm) detectors, 0.1 M NaNO3 as mobile phase, flow rate 0.8 mL/min and tracers dextran and pullulan (polymers of similar hydrodynamic volume as compared to HA) as molar mass standards. The samples showed molar mass distributions in the range of 103 to 107 Da, after being precipitated and dissolved four times. For these samples, the average molar mass was found to be in the order of magnitude of 105 Da. In the semi-preparative column Superose, it was possible to separate HA fractions, with molar mass above 105 Da, and free of proteic contaminants, in an elution interval of 10 minutes
O Ãcido HialurÃnico (AH) à um polÃmero linear, nÃo ramificado, composto por unidades dissacarÃdicas simples, cuja massa molar pode se distribuir num largo intervalo (104-107 Da). à usado em aplicaÃÃes farmacÃuticas e cosmÃticas dependendo de sua massa molar mÃdia. A separaÃÃo de macromolÃculas da ordem de grandeza do AH à possÃvel atravÃs da Cromatografia de permeaÃÃo em gel (GPC). Este trabalho tem como objetivo estudar a caracterizaÃÃo, purificaÃÃo e fracionamento do AH produzido por microorganismos, utilizando GPC. O AH, cedido pelo Departamento de Processos BiotecnolÃgicos (DPB/FEQ/UNICAMP), foi obtido por cultivo de microorganismos - Streptococcus zooepidemicus - em meio de cultura sintÃtico. ApÃs centrifugaÃÃo do caldo de fermentaÃÃo, o AH foi precipitado com etanol e ressuspenso em soluÃÃo salina, sendo esta etapa de prÃ-purificaÃÃo executada atà quatro vezes. A presenÃa de contaminantes protÃicos foi identificada por eletroforese em gel de poliacrilamida sob condiÃÃes desnaturantes (SDS-PAGE) e quantificada pelo mÃtodo de Bradford, obtendo-se 97,20 μg/mL, para a amostra de AH apÃs quatro precipitaÃÃes em etanol e ressuspensÃes em NaNO3 0,1 M. Para as determinaÃÃes de concentraÃÃo de AH nas amostras estudadas, utilizou-se o sal sÃdico de AH microbial comercial (Sigma Aldrich - EUA) como padrÃo. Quantificando-se a amostra de AH apÃs quatro precipitaÃÃes em etanol e ressuspensÃes em NaNO3 0,1 M, obteve-se 783,70 μg/mL. A distribuiÃÃo da massa molar do AH foi avaliada por GPC, em escala analÃtica, utilizando coluna Shodex OHPak-SB806M-HQ e, em escala semi-preparativa, a coluna Superose 6, detectores de Ãndice de refraÃÃo e UV/Vis (280 nm), NaNO3 0,1 M como fase mÃvel, vazÃo de 0,8 mL/min e padrÃes de Dextrana e Pullulan (polÃmeros de volume hidrodinÃmico semelhante ao AH) como marcadores de massa molar (5,2x103 - 7,9x106 Da e 5,8x103 â 8,53x105 Da, respectivamente). A amostra apresentou uma distribuiÃÃo polimÃrica na faixa de 103 a 107 Da, apÃs quatro precipitaÃÃes em etanol e ressuspensÃes em NaNO3 0,1 M, sendo sua massa molar mÃdia da ordem de 105 Da. Foi possÃvel separar fraÃÃes de AH, acima de 105 Da, livre de contaminantes protÃicos, num intervalo de aproximadamente 10 minutos, na coluna Superose 6
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Siochi, Emilie J. "Dilute solution studies of molecular weight distributions of nitrocellulose, modified lignins and PMMA graft polymers." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54423.
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Dilute solution properties of three difficult-to-analyze macromolecular systems were investigated and clarified. Two were notorious for having highly time-in-solution dependent properties, nitrocellulose and lignin, while the third was an ideal model branched methacrylate polymer with which to examine unanswered questions in polymer hydrodynamic behavior.
Gel permeation chromatography with a differential viscosity detector (GPC/DV) was employed to study the dilute solution properties of various polymers, specifically their absolute molecular weight distributions and hydrodynamic behavior. The study was divided into three parts.
The first part focused on the time dependent change in molecular weight of nitrocellulose. Samples having 12.58% and 13.5% levels of nitration were investigated in THF and EtOAc. GPC/DV, LALLS, FT-IR and intrinsic viscosity experiments revealed that the materials existed as associated molecules in solution which decreased in molecular weight upon storage to extents dependent on the solvent.
The second part was an examination of the hydrodynamic behavior of hydroxypropylated lignins using GPC/LALLS/DV and VPO. These materials were found to increase in molecular weight upon storage in solution due to association. Special precautions had to be taken in running experiments to obtain the correct molecular weights and molecular weight distributions.
The last part involved a fundamental study of PMMA-g-PMMA's having similar molecular weights but containing different levels of branching. Variable temperature GPC/LALLS/DV was employed to obtain molecular weight distributions, branching parameters, average chain dimensions and information on the hydrodynamic behavior of these branched systems. Samples containing up to 40% of long chain branching were found to obey the universal calibration analytic scheme of GPC.Ph. D.
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O'Driscoll, Nelson James. "Analysis of methyl mercury binding to humic and fulvic acids by sephadex gel permeation chromatography hydride generation ICP-MS." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ40484.pdf.
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Zhu, Honghui. "Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and gel permeation chromatography to polymer analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0012/MQ59913.pdf.
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Ma, Yaning. "Characterization of Membrane Permeability and Polymer-Stabilized Model Membranes." Thesis, The University of Arizona, 2007. http://hdl.handle.net/10150/193347.
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The permeability of lipid bilayer membranes to glucose and carboxyfluorescein has been studied in model membranes. Using an enzyme assay, the permeability of glucose was monitored spectrometrically with both large and giant unilamellar vesicles (LUVs and GUVs). The permeability of carboxyfluorescein was studied by entrapping the dye and monitoring its leakage over time from a single GUV. Permeability study using GUVs may provide new information that cannot be obtained from LUVs.The stability of lipid membranes was enhanced by incorporating polymer scaffold. LUVs were prepared with hydrophobic monomers partitioned and then polymerized inside the hydrophobic interior of the lipid bilayers. The sizes of the formed polymers were characterized using gel permeation chromatography and mass spectrometry. This study suggests that large molecular weight polymers were formed inside the lipid bilayers and that the stability of the membranes is related to the size of the polymers.
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Ashayeri, Diane L. "Soy protein-xanthan gum interaction:stability and rheology." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/91074.
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This study investigated the effects of ionic strength, pH, gum concentration, and protein type on protein - xanthan gum interactions. Commercial soy sauce and tamari sauce as well as model systems of soy protein isolate and whey protein concentrate were the sources of protein used for evaluation with xanthan gum.
Preliminary research indicated that when either soy sauce or tamari sauce were mixed with xanthan gum, stable solutions with notable viscosity synergisms resulted. The soy protein and whey protein systems were subsequently prepared with a range of 0 to 5% added sodium chloride. Results indicated that an equilibrium existed between proteins and xanthan gum such that increased sodium chloride initially increased solution stability; but when in excess, the sodium chloride led to a loss of protein - xanthan gum solution solubility and in some cases to precipitation. Precipitation was also noted at the pH extremes of 2,3, and 9 and when xanthan gum was present in excess, or at 0.25%.
The effects of sodium chloride, protein type, and pH on the rheological parameters of model solutions were also examined. Higher sodium chloride levels yielded greater viscosity synergisms. Those solutions made.with intact protein were generally higher in apparent viscosity than similar solutions made with hydrolyzed protein. Solutions at pH 5 were generally higher in viscosity than were similar solutions at pH 7.
Several factors that appeared to affect the stability, solubility, and the rheological parameters of protein - xanthan gum solutions were sodium chloride concentration, gum concentration, pH, and protein type.M.S.
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Acun, Tolga. "Isolation And Characterization Of The K4 Type Yeast Killer Toxin." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1218684/index.pdf.
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Killer yeasts secrete polypeptide toxins which kill sensitive cells of their own
species and frequently those of other species and genera of yeasts. These protein compounds are designated as killer toxins. Also killer toxins of certain yeast strains have potential growth inhibitory activity on gram-positive pathogenic bacteria and plant pathogenic fungi. The yeasts are immune to their own killer protein. The killer phenomenon can be utilized for the protection of fermentation process against contaminating yeasts and for biological control of undesirable yeasts in the preservation of foods. The killer trait can also be used to produce large amount of foreign proteins in yeast. In the medical field , it is thought that their anti-microbial and anti-mycotic activity could be exploited in a therapeutic strategy.
Yeast killer toxins are classified into 11 types according to their killing
spectra and immunity-specificities such as K1, K2, etc. Altough there is
considerable amount of published information concerning the applications of yeast killer toxins , among the 11 types , only K1 , K2 and K6 have been characterized. In this study , it was aimed to purify and characterize the K4 type yeast killer toxin secreted by the Hansenula anomala NCYC 432. Gel permeation chromatography was performed to isolate the killer toxin by using a HPLC system. The toxin was
shown to be a glycoprotein having a molecular mass of between 49.08 kDa and 47.25 kDa and isoelectric point of between 3.77 and 3.41.
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Urban, Vanessa Migliorini [UNESP]. "Efeito de tratamentos pós-polimerização sobre o peso molecular, o grau de conversão, a temperatura de transição vítrea e a liberaçãp in vitro de monômero residual, plastificante e produtos de degradação de resinas acrílicas para reembasamento imediato." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/106685.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Os objetivos deste estudo foram avaliar: 1. o efeito de tratamentos póspolimerização (MW-irradiação por energia de microondas e WB-imersão em água aquecida) sobre o grau de conversão (DC) de resinas acrílicas para reembasamento imediato (Ufi Gel hard-U, Kooliner-K e Tokuso Rebase Fast-T) e de uma resina acrílica para base de prótese (Lucitone 550-L), submetida a dois ciclos de polimerização (LS-curto e LL-longo) por espectroscopia FT-Raman; 2. o peso molecular (M w) do pré-polímero dos materiais U, K, T e L e das amostras polimerizadas da resina K (controle; MW e WB) por GPC; 3. o efeito de MW e WB na temperatura de transição vítrea (Tg) das resinas para reembasamento imediato (Duraliner II-D, K, New Truliner-N, U e T) e da resina para base de prótese (LS e LL) por DSC; 4. o efeito de WB na liberação de compostos residuais (isobutil metacrilato-IBMA, 1,6-hexanediol dimetacrilato-1,6-HDMA e DBNP-dibutil-n-ftalato) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE; 5. o efeito de WB na liberação de produtos de degradação (ácido metacrílico-MA e ácido benzóico-BA) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE. Amostras do grupo controle não foram submetidas a nenhum tratamento. Os resultados de DC (%) foram analisados pelo teste de Kruskal-Wallis ( =0,05). Os resultados de Tg (ºC) foram analisados pela análise de variância (ANOVA), seguido pelo teste de Tukey ( =0,05). Os resultados da liberação de monômero ' 224 residual e plastificante (μg/mL) foram submetidos aos testes de Wilcoxon ou de Mann-Whitney ( =0,05). Os resultados da liberação de produtos de degradação (μg/mL) foram submetidos aos testes de Wilcoxon, Mann-Whitney ou Kruskal- Wallis ( =0,05). Para as amostras do grupo controle, não houve diferenças significantes entre o DC das resinas U e LL e entre...
The aims of this study were to evaluate: 1. the effect of post-polymerization treatments (MW-microwave irradiation and WB-water-bath) on the degree of conversion (DC) of reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long) by FT-Raman spectroscopy; 2. the molecular weight (M w) of the powder of U, K, T, and L materials and of K polymerized specimens (control; MW; and WB) by GPC; 3. the effect of MW and WB on the glass transition temperature (Tg) of the reline resins (Duraliner II-D, K, New Truliner-N, U and T) and the heat-polymerized resin (LS and LL) by DSC; 4. the effect of WB on the leaching of residual compounds (isobutyl methacrylate- IBMA, 1,6-hexanediol dimethacrylate-1,6-HDMA, and DBNP-dibutyl-nphthalate) from the reline resins (K, N, U, and T) in artificial saliva by HPLC; 5. the effect of WB on the leaching of degradation products (methacrylic acid-MA and benzoic acid-BA) from the reline resins K, N, U, and T in artificial saliva by HPLC. Control group specimens were left untreated. DC (%) data were analyzed using Kruskal-Wallis test (_=.05). Tg (ºC) data were analyzed using ANOVA/Tukey's test (_=.05). The results (æg/mL) of residual monomer and plasticizer leachability were submitted to Wilcoxon or Mann-Whitney tests (_=.05). The results (æg/mL) of degradation products leachability were submitted to Wilcoxon, Mann-Whitney or Kruskal-Wallis tests (_=.05). For DC control specimens, there were no significant differences between U and LL and among LL, K, and T. LS specimens had the highest DC. Only material K exhibited an increased DC after WB. All powders had M w from 4.0x105 to 6.5x105 and narrow M w distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with M w values similar to that of K powder...(Complete abstract, click electronic address below).
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Malere, Caroline Paganucci dos Reis. "Síntese e caracterização de padrão de poliestireno para cromatografia de permeação em gel através da polimerização via radical livre controlada mediada por radicais nitróxidos." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266829.
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Orientador: Liliane Maria Ferrareso LonaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: A Cromatografia de Permeação em Gel ou "Gel Permeation Chromatography (GPC), também conhecida como Cromatografia de Exclusão por Tamanho ou "Size Exclusion Chromatography" (SEC) é uma das técnicas analíticas mais utilizadas para separação e caracterização de polímeros naturais e sintéticos, copolímeros e proteínas, fornecendo informações distribuição de massa molar (MWD), viscosidade intrínseca (IV) e polidispersividade (PDI). A importância de sua resposta na análise de determinado polímero se reflete em termos de sua processabilidade, uma vez que as propriedades mecânicas e químicas são drasticamente afetadas por sua massa molar média, tamanho da cadeia e distribuição. Na técnica de GPC os padrões utilizados são de primordial importância para obtenção de resultados confiáveis, pois são utilizados nas construções de curvas de calibrações necessárias para aquisição dos resultados quanti e qualitativos na técnica. Apesar da vasta utilização da técnica de GPC no Brasil, tanto em centros de pesquisa como em indústrias químicas e petroquímicas, os padrões disponíveis para comercialização são todos adquiridos no exterior, por meio de importação a altos custos. Visto a necessidade de mudança desse paradigma, este trabalho tem como objetivo desenvolver um produto nacional utilizando a polimerização via radical livre mediada por radicais nitróxidos (NMRP), também chamada "living free radical polymerization (LFRP)". O padrão escolhido para o estudo foi o poliestireno (PS), por ser ele um dos padrões mais utilizados na calibração de análise de GPC orgânico. Um dos desafios enfrentados neste trabalho foi a obtenção de polímeros com índices de polidispersividade (PDI) variando de 1 a 1,10, distribuição de massa molar (MWD) estreita e alto grau de pureza, utilizando pela primeira vez uma mistura de iniciadores no processo NMRP. A NMRP é uma técnica robusta e inovadora comparada com a polimerização iônica que é atualmente o processo empregado para obtenção de polímeros com valores de PDI muito baixos. O processo NMRP possui vantagens frente à polimerização iônica para produção de polímeros com estrutura controlada, pois nele não são necessários etapas de purificações complexas, sendo que as reações requerem menos condições estritas em relação a impurezas e temperaturas de trabalho. Este é um processo simples e barato, na qual as reações podem ser realizadas em ampolas de vidros
Abstract: Gel Permeation Chromatography, also known as Size Exclusion Chromatography, is the most employed technique to characterize macromolecules such as proteins, copolymers, natural and synthetic polymers. It provides information such as molecular weight distribution (MWD), intrinsic viscosity (IV) and polydispersity (PDI). The importance of its response reflects in terms of polymer processability once the mechanic and chemicals properties are drastically affected by the polymer average molecular weight, chain size and distribution. The standards in the GPC technique have a great importance to obtain reliable results because they are employed in calibration curves needed to acquire the quantitative and qualitative data. Despite the wide use of GPC in Brazil at research centers, chemical and petrochemical industries, all the standards available are obtained outside the country through high importation costs. To change this paradigm, this work aims to develop a national product using the pseudo-living radical polymerization or living free radical polymerization (LFRP), which is a robust and innovative technique in the polymerization science area. The standard chosen was the polystyrene, which is the most used polymer in calibration curves of organic GPC analysis. Our challenge in this work was to obtain a controlled structure polymer with polydispersity index (PDI) between 1 and 1.10, narrow molecular weight distribution (MWD) and high purity degree, using to the best of our knowledge for the first time a mixture of initiators in a NMRP process. The NMRP is a robust and innovative technique compared with the ionic polymerization that is the currently employed process to obtain polymers with very low PDI. The advantages of NMRP process over ionic polymerization to produce controlled structure polymers are that no complicated purification steps are needed, controlled radical reactions require less stringent conditions for impurities and working temperatures, it is a simple and cheaper process, where the reactions can be carried out into glass ampoules
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
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Jayapalan, Swapna. "Purification and structural analysis of Newcastle disease virus V protein and flowering locus T (FT) protein." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-09242007-090456.
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Urban, Vanessa Migliorini. "Efeito de tratamentos pós-polimerização sobre o peso molecular, o grau de conversão, a temperatura de transição vítrea e a liberaçãp in vitro de monômero residual, plastificante e produtos de degradação de resinas acrílicas para reembasamento imediato /." Araraquara : [s.n.], 2007. http://hdl.handle.net/11449/106685.
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Resumo: Os objetivos deste estudo foram avaliar: 1. o efeito de tratamentos póspolimerização (MW-irradiação por energia de microondas e WB-imersão em água aquecida) sobre o grau de conversão (DC) de resinas acrílicas para reembasamento imediato (Ufi Gel hard-U, Kooliner-K e Tokuso Rebase Fast-T) e de uma resina acrílica para base de prótese (Lucitone 550-L), submetida a dois ciclos de polimerização (LS-curto e LL-longo) por espectroscopia FT-Raman; 2. o peso molecular (M w) do pré-polímero dos materiais U, K, T e L e das amostras polimerizadas da resina K (controle; MW e WB) por GPC; 3. o efeito de MW e WB na temperatura de transição vítrea (Tg) das resinas para reembasamento imediato (Duraliner II-D, K, New Truliner-N, U e T) e da resina para base de prótese (LS e LL) por DSC; 4. o efeito de WB na liberação de compostos residuais (isobutil metacrilato-IBMA, 1,6-hexanediol dimetacrilato-1,6-HDMA e DBNP-dibutil-n-ftalato) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE; 5. o efeito de WB na liberação de produtos de degradação (ácido metacrílico-MA e ácido benzóico-BA) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE. Amostras do grupo controle não foram submetidas a nenhum tratamento. Os resultados de DC (%) foram analisados pelo teste de Kruskal-Wallis ( =0,05). Os resultados de Tg (ºC) foram analisados pela análise de variância (ANOVA), seguido pelo teste de Tukey ( =0,05). Os resultados da liberação de monômero ' 224 residual e plastificante (μg/mL) foram submetidos aos testes de Wilcoxon ou de Mann-Whitney ( =0,05). Os resultados da liberação de produtos de degradação (μg/mL) foram submetidos aos testes de Wilcoxon, Mann-Whitney ou Kruskal- Wallis ( =0,05). Para as amostras do grupo controle, não houve diferenças significantes entre o DC das resinas U e LL e entre...(Resumo completo, clicar acesso eletrônico abaixo)Abstract: The aims of this study were to evaluate: 1. the effect of post-polymerization treatments (MW-microwave irradiation and WB-water-bath) on the degree of conversion (DC) of reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long) by FT-Raman spectroscopy; 2. the molecular weight (M w) of the powder of U, K, T, and L materials and of K polymerized specimens (control; MW; and WB) by GPC; 3. the effect of MW and WB on the glass transition temperature (Tg) of the reline resins (Duraliner II-D, K, New Truliner-N, U and T) and the heat-polymerized resin (LS and LL) by DSC; 4. the effect of WB on the leaching of residual compounds (isobutyl methacrylate- IBMA, 1,6-hexanediol dimethacrylate-1,6-HDMA, and DBNP-dibutyl-nphthalate) from the reline resins (K, N, U, and T) in artificial saliva by HPLC; 5. the effect of WB on the leaching of degradation products (methacrylic acid-MA and benzoic acid-BA) from the reline resins K, N, U, and T in artificial saliva by HPLC. Control group specimens were left untreated. DC (%) data were analyzed using Kruskal-Wallis test (_=.05). Tg (ºC) data were analyzed using ANOVA/Tukey's test (_=.05). The results (æg/mL) of residual monomer and plasticizer leachability were submitted to Wilcoxon or Mann-Whitney tests (_=.05). The results (æg/mL) of degradation products leachability were submitted to Wilcoxon, Mann-Whitney or Kruskal-Wallis tests (_=.05). For DC control specimens, there were no significant differences between U and LL and among LL, K, and T. LS specimens had the highest DC. Only material K exhibited an increased DC after WB. All powders had M w from 4.0x105 to 6.5x105 and narrow M w distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with M w values similar to that of K powder...(Complete abstract, click electronic address below).
Orientador: Ana Lucia Machado
Coorientador: Quezia Bezerra Cass
Banca: Carlos Eduardo Vergani
Banca: Carlos Alberto dos Santos Cruz
Banca: Marcelo Ferraz Mesquita
Banca: Regina Vincenzi Oliveira
Doutor
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Dixon, Daniel Wayne. "Characterization of Commercial Pectin Preparations by Spectroscopic and Chromatographic Techniques." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etd/1910.
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Pectin has a long history as a food additive. However, elucidation of its fine structural and property relationships remains elusive. Recent research has focused on pectin's ability to complex with divalent heavy metals to aid in characterizing it. Commercial pectins of unknown composition were obtained from local grocers. Purified pectin samples from orange peel, lemon peel, and apple pomace, each of low and high levels of methyl esterification and of unknown distribution pattern were also purchased. Instead of metal complexation, several highly absorbing dyes such as Ruthenium Red, Nile Blue, and Acridine Orange were used to complex with the pectins and their resulting UV-Vis spectral patterns were employed to determine if one can characterize the different pectins. Chemometric methods are also included to aid in distinguishing them apart.
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Mandimika, Nyaradzo. "Evaluation of the pharmaceutical availability of erythromycin from topical formulations." Thesis, Rhodes University, 2008. http://eprints.ru.ac.za/1176/.
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Hansson, Henrik. "Structure and function of the SH3 domain from Bruton´s tyrosine kinase." Doctoral thesis, KTH, Biotechnology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3289.
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Todorovic, Zoran. "Avaliação da viscosidade e massa molar de quitosanas modificadas enzimaticamente." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267630.
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Orientador: Telma Teixeira FrancoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A biocompatibilidade, biodegradabilidade e o fato de ser um polimero catiônico bioadesivo fazem a quitosana um material atrativo para inúmeras aplicações na área biotecnológica, agrícola, farmacêutica e médica. As quito sanas com massas molares baixas e os oligômeros têm maiores perspectivas nas últimas duas áreas. O objetivo deste projeto de pesquisa foi a obtenção de polimeros com massa molar média reduzida devido à ação da enzima papaína. Empregando papaína livre e em forma imobilizada a redução da massa molar da quito sana foi estudada. Quitina foi utilizada como suporte para imobilização da papaína e para imobilização da proteína modelo albumina de soro bovino. Experimentos com todos estes materiais foram realizados para estudar os efeitos da modificação da quito sana. Os experimentos foram conduzidos em reatores batelada com pH e temperatura controlados. Soluções da quito sana (1 %) foram preparadas utilizando ácido lático ou ácido acético para solubilização. Duas técnicas para determinação da massa molar da quito sana foram utilizadas. Em primeiro lugar, a visco simetria foi empregada sendo esta a técnica mais comum para investigação de redução da massa molar. Redução da viscosidade de soluções de quitosana foi associada à diminuição da massa molar média. Outro método utilizado para a determinação de massas molares foi a cromatografia de permeação em gel, que é considerado um método relativo de determinação de massa molar, pois necessita de padrões dos polimeros para a construção de uma curva padrão. A massa molar determinada por estes dois métodos é dependente do tamanho da molécula (diâmetro). O método absoluto de determinação da massa molar com detector de espalhamento de luz também foi utilizado. Este detector conectado on-line com cromatografia de permeação em gel fornece dados absolutos da massa molar média. Luz espalhada de diferentes partes da molécula do polimero em diferentes ângulos geram o valor correto da massa molar sem utilização dos padrões. Os resultados mostraram o efeito superior na redução da massa molar utilizando papaína em comparação com outros materiais utilizados. Esta redução da massa molar média é rápida e acentuada nos primeiros minutos da reação, em comparação com a continuação do processo
Abstract: Biocompatibility, biodegradability and the fact of being bioadhesive polycationic polymer make chitosan an attractive material for various applications in agricultural and biotechnological, pharmaceutical and medical fields. Chitosans with lower molecular weights and oligomers OOve major perspectives in the last two fields. An objective of this project of research was the production of polymers with reduced molecular weight due to the action of enzyme papain. Applying papain in the free and immobilized form the reduction of molecular weight of chitosan was studied. Chitin was used as a support for the immobilization of papain and for the immobilization of model protein bovine serum albumin. Experiments with all these materiais were realized to study the effects of modification of chitosan. Experiments were run using batch reactors at controled pH and temperature. Chitosan solutions (1 %) were prepared using lactic acid or acetic acid for solubilization. Two different techniques were used for determination of molecular weight of chitosan. First viscosimetry was applied as the most common technique used for investigation of reduction of molecular weights. Reduction of viscosity of chitosan solutions is associated with the reduction of molecular weight. The other method used for determination of molecular weights is gel permeation chromatography toot is considered a relative method of determination of molecular weights as it requires polymeric standards for the construction of the standard curve. Molecular weight determined by these two methods is dependant of the molecular size (diameter). Absolute method of determination of molecular weights through measurements with detector of light scattering was aIso applied in this studies. This detector connected on-line with gel penneation chromatography provides us with the absolute molecular weights. This method does not require standards measuring the light scattered from different parts of the polymeric molecule in different angles generating in this way the correct value of molecular weight. Results show the superior effect of papain on the reduction of molecular weight compared to the other materiais used. This reduction of molecular weight is fast, pronounced in the :fust minutes of the reaction in comparison with the continuation of the process
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
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Bardet, Michel. "Analyse structurale des lignines par résonance magnétique nucléaire : utilisation des nouvelles séquences impulsionnelles et étude des lignines extraites de bois traité par autohydrolyse rapide." Grenoble 1, 1987. https://hal.archives-ouvertes.fr/tel-01713695.
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Etude des modifications structurales de la lignine de bois de populus tremoloides traite par autohydrolyse par spectrometrie rmn du **(13)c et analyse des composes de faible masse moleculaire isoles des lignines extraites
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Fiebiger, Caroline. "Untersuchungen zu Eintrag, Verteilung und Verbleib natürlicher organischer Wasserinhaltstoffe aus moorgeprägten Einzugsgebieten von Trinkwasserspeichern." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1176364354365-11781.
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In den letzten 15 Jahren wurde in einigen Mittelgebirgsregionen Zentraleuropas ein regional un-terschiedlich starker Anstieg der Konzentration gelösten organischen Kohlenstoffes (DOC) in Oberflächengewässern festgestellt. Besonders betroffen von dieser Entwicklung sind für die Trink-wasserproduktion genutzte Talsperren. Durch den erhöhten DOC-Gehalt wird die Trinkwasser-aufbereitung nicht nur kostenintensiver, sondern bekommt auch zunehmend Probleme bei der Wahrung der Trinkwasserqualität. Die Quellen des DOC sind in den Einzugsgebieten befindliche Moore und hydromorphe Nassstandorte. Die Ursachen für den in den vergangenen Jahren doku-mentierten Mehraustrag sind äußerst komplex und beinhalten sowohl klimatische als auch nut-zungsbedingte Veränderungen. Ziel der vorliegenden Arbeit ist, den Charakter des DOC näher zu bestimmen, um die für die Wasseraufbereitung problematischen Fraktionen zu benennen und Ansatzpunkte für regulierende Maßnahmen aufzuzeigen. Die Charakterisierung erfolgte an einem LC-OCD-System (Liquid Chromatography – Organic Carbon Detection) am Beispiel der drei Tal-sperrensysteme Muldenberg, Carlsfeld (Westerzgebirge) und Fláje (Osterzgebirge, Tschechien). Die Talsperren weisen unterschiedliche DOC-Gehalte auf. Die Ergebnisse zeigen, dass der DOC aller Untersuchungsgebiete sowohl in den Zuflüssen, dem Talsperrenwasser bzw. Rohwasser als auch dem Reinwasser der Wasserwerke von Huminstoffen dominiert wird. DOC-Schwankungen sind folglich auf Schwankungen der Huminstoffkonzentrationen zurückzuführen. In den Zuflüs-sen treten die höchsten Huminstoffkonzentrationen während der Schneeschmelze im Frühjahr und bei Starkniederschlägen im Sommer und Herbst auf. Niedrige Konzentrationen sind an Bo-dengefrornis oder Trockenphasen im Sommer gebunden. In den Talsperren tritt im Sommer eine Schichtung der Huminstoffe auf, bei der an der Oberfläche durch photolytischen Abbau niedrige-re Konzentrationen und in Abhängigkeit von der Talsperrentiefe durch die Einschichtung der Zuflüsse am Grund höhere Konzentrationen auftreten. Die Verteilung im Winter ist allein von der Einschichtung der Zuflüsse abhängig. Die Verteilung der Building Blocks (Huminstoffhydrolysate) ist im Sommer der der Huminstoffe entgegengesetzt, da sich beim photolytischen Abbau von Hu-minstoffen Building Blocks bilden. Während der Zirkulationen sind die Konzentrationen der Hu-minstofffraktionen im gesamten Tiefenprofil gleich. In den Talsperren Muldenberg und Carlsfeld wurde im Untersuchungszeitraum unter Berücksichtigung der technischen Gegebenheiten und anderer Wassergütekriterien der optimale Rohwasserentnahmehorizont (niedrigstmögliche Hu-minstoffkonzentration) gewählt. In der Talsperre Fláje könnte die Rohwasserqualität durch Instal-lation eines schwenkbaren Entnahmerohres erheblich verbessert werden. In den Wasserwerken sind die Huminstofffraktionen mit abnehmender Molekülgröße schwieriger zu entfernen. Die relativ niedermolekularen Building Blocks sind die am schwersten entfernbaren DOC-Bestandteile. Auf Grundlage mathematischer Beziehungen zu SAK254 bzw. DOC wurde ein Programm (DOCQuaC – DOC-Quality Calculator) entwickelt, mit dessen Hilfe die Huminstofffraktionen über diese Grundparameter ermittelt werden können. Neben der Fraktionsquantifizie-rung besteht im Programm die Möglichkeit zur Berechnung der Eliminierungsleistung, so dass beispielsweise nach der Durchführung einer Maßnahme zur Verbesserung der DOC-Entfernung eine unmittelbare Aussage über den Effekt auf die Fraktionen vorliegtFor the last 15 years a change of Dissolved Organic Carbon (DOC) has been taking place in surface waters of Middle European Highlands. The degree of this increase is regionally dependent. The reasons as well as the consequences of this development are of high complexity. The changes are expressed in an increase of middle DOC values and, additionally, an increase of annual changes. Reservoirs, used for drinking water production, are particularly affected, because the heightened DOC content increases the costs for drinking water treatment, and currently it is not possible to maintain a good drinking water quality. The main DOC source are peat bogs, situated in the catchments. The cause of the increasing DOC output from peat bogs are very complex and contain changes as well in climate as in land use. The aim of this presented dissertation was to gain more information about the character of DOC, so that those fractions can be determined which are problematically to remove inside the waterworks. On that base it should be possible to find some starting points for more regulating measures. The analytical characterisation was carried out by the help of a LC-OCD-System (Liquid Chromatography – Organic Carbon Detection), exemplary for the reservoir systems Muldenberg, Carlsfeld (Western Ore Mountains) and Fláje (Eastern Ore Mountains, Czech Republic). Although the DOC concentrations are very different in the reser-voirs, it was always dominated by humic substances, namely as well in the tributaries, as in the raw and treated water. Thus changes in the DOC concentration are due to changes in the concen-tration of humic substances. In spring and summer occur the highest concentrations of humic substances in the tributaries. Low concentrations are linked with frost in winter or dry periods in summer. In the reservoirs in summer a stratification of humic substances shapes up, with lower concentration near the water surface (caused by photolytical degradation) and accordingly higher concentration near the ground (layering of influxes). Distribution in winter only depends on the layering of the influxes. In summer the concentration of Building Blocks (humic substance hydro-lysates) is opposite to that of humic substances, because of the creation of Building Blocks at the photolytical degradation. During circulation the concentration of all humic substance fractions are equal in each reservoir layer. In the reservoirs Muldenberg and Carlsfeld, a further optimisation of the raw water withdrawal horizon is not possible. In the reservoir Fláje the raw water could be much improved by installing a movable withdrawal device. With decreasing molecular size the elimination of the humic fractions gets more difficult in the waterworks. Most difficult to eliminate are Building Blocks. On the basis of the mathematical cor-relation between humic fractions and the SAC254 and DOC a program (DOCQuaC – DOC-Quality Calculator) has been developed, which enables die calculation of humic concentrations by enter-ing these general parameters. In addition to the calculation of the concentrations it is possible to calculate the elimination capacity for the humic fractions. Thus the effects of measures on the humic fractions, which could be done for optimisation of the elimination capacity, can be imme-diately observed
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Yee, Melinda Chua Fui. "An investigation of the biology and chemistry of the Chinese medicinal plant, Amorphophallus konjac." Thesis, University of Wolverhampton, 2011. http://hdl.handle.net/2436/237603.
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Konjac glucomannan (KGM), the main biologically active constituent of konjac flour extracted from corms of Amorphophallus konjac (konjac), can be used to prepare functional foods and may also have potential as a pharmaceutical product to combat obesity. The current study employed three experimental approaches to study the biology and chemistry of konjac, namely (1) glasshouse experiments to study the morphogenesis, growth and productivity of konjac plants, (2) a histological and immunocytochemical investigation of the localisation and developmental regulation of the deposition and metabolism of KGM in developing corm tissues, and (3) a comparative study of methodologies for the extraction and analysis of KGM. The current data demonstrated a morphological and functional separation between the ventral and dorsal regions of corms. The ventral region appeared to function as a source during the initial period of shoot development, while the dorsal region appeared to operate as a sink after the development of mature canopy. Once the corm reached maturity, both an inflorescence and a leaf were produced within a single season. It has also been demonstrated that the age of the ‘mother’ corm is an important factor affecting the quality of offsets produced. An anti-mannan antiserum detected a temporally regulated pattern of mannan epitope production within glucomannan idioblasts in developing corm tissues, with increased expression as the corm approached maturity/dormancy. The current observations also suggest that the mobilization of KGM initiates at the periphery of the corm and proceeds inwards towards the centre of the corm. Compositional analysis showed that the purified konjac flour (PKF) produced using a modified extraction procedure contained 92% glucomannan, with a weight average molecular weight (Mw), polydispersity index (PDI) and degree of acetylation (DA) of 9.5 ± 0.6 x 105 gmol-1, 1.2 and 2.8 wt. %. These data, plus Fourier-transform infrared spectral (FTIR) and zero shear viscosity analyses of the extract (PKF) were all consistent with the literature. Comparison of three existing methodologies for the quantitative analysis of the KGM content, namely 3,5-dinitrosalicylic acid (3,5-DNS), phenol-sulphuric acid and enzymatic colorimetric assays; indicated that the 3,5-DNS colorimetric assay was the most reproducible and accurate method, with a linear correlation coefficient of 0.997 and recoveries between 97% and 103% across three spiking levels of starch. In summary, this study has provided a better understanding of aspects of the biology and cultivation of A. konjac and has also produced methodologies which can be used as the basis for an improved good laboratory practice (GLP) for the commercial extraction and analysis of this multifunctional natural polymer.
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CUNHA, TATIANA F. da. "Aplicação do poli(epsilon-caprolactona) com estrutura estrelada para obtenção de microesferas biorreabsorvíveis." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10544.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Mouflou, Zoubida. "Reseaux polymeres hydrophiles : synthese et application en chromatographie d'exclusion sterique en milieu aqueux." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13150.
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Polymeres tridimensionnels non ioniques presentant une bonne tenue mecanique constitues par un squelette hydrophobe rigide reticule, dotes de greffons hydrophiles polyoxiranne. Broyage des gels et tamisage des grains
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Fiebiger, Caroline. "Untersuchungen zu Eintrag, Verteilung und Verbleib natürlicher organischer Wasserinhaltstoffe aus moorgeprägten Einzugsgebieten von Trinkwasserspeichern." Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A25004.
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In den letzten 15 Jahren wurde in einigen Mittelgebirgsregionen Zentraleuropas ein regional un-terschiedlich starker Anstieg der Konzentration gelösten organischen Kohlenstoffes (DOC) in Oberflächengewässern festgestellt. Besonders betroffen von dieser Entwicklung sind für die Trink-wasserproduktion genutzte Talsperren. Durch den erhöhten DOC-Gehalt wird die Trinkwasser-aufbereitung nicht nur kostenintensiver, sondern bekommt auch zunehmend Probleme bei der Wahrung der Trinkwasserqualität. Die Quellen des DOC sind in den Einzugsgebieten befindliche Moore und hydromorphe Nassstandorte. Die Ursachen für den in den vergangenen Jahren doku-mentierten Mehraustrag sind äußerst komplex und beinhalten sowohl klimatische als auch nut-zungsbedingte Veränderungen. Ziel der vorliegenden Arbeit ist, den Charakter des DOC näher zu bestimmen, um die für die Wasseraufbereitung problematischen Fraktionen zu benennen und Ansatzpunkte für regulierende Maßnahmen aufzuzeigen. Die Charakterisierung erfolgte an einem LC-OCD-System (Liquid Chromatography – Organic Carbon Detection) am Beispiel der drei Tal-sperrensysteme Muldenberg, Carlsfeld (Westerzgebirge) und Fláje (Osterzgebirge, Tschechien). Die Talsperren weisen unterschiedliche DOC-Gehalte auf. Die Ergebnisse zeigen, dass der DOC aller Untersuchungsgebiete sowohl in den Zuflüssen, dem Talsperrenwasser bzw. Rohwasser als auch dem Reinwasser der Wasserwerke von Huminstoffen dominiert wird. DOC-Schwankungen sind folglich auf Schwankungen der Huminstoffkonzentrationen zurückzuführen. In den Zuflüs-sen treten die höchsten Huminstoffkonzentrationen während der Schneeschmelze im Frühjahr und bei Starkniederschlägen im Sommer und Herbst auf. Niedrige Konzentrationen sind an Bo-dengefrornis oder Trockenphasen im Sommer gebunden. In den Talsperren tritt im Sommer eine Schichtung der Huminstoffe auf, bei der an der Oberfläche durch photolytischen Abbau niedrige-re Konzentrationen und in Abhängigkeit von der Talsperrentiefe durch die Einschichtung der Zuflüsse am Grund höhere Konzentrationen auftreten. Die Verteilung im Winter ist allein von der Einschichtung der Zuflüsse abhängig. Die Verteilung der Building Blocks (Huminstoffhydrolysate) ist im Sommer der der Huminstoffe entgegengesetzt, da sich beim photolytischen Abbau von Hu-minstoffen Building Blocks bilden. Während der Zirkulationen sind die Konzentrationen der Hu-minstofffraktionen im gesamten Tiefenprofil gleich. In den Talsperren Muldenberg und Carlsfeld wurde im Untersuchungszeitraum unter Berücksichtigung der technischen Gegebenheiten und anderer Wassergütekriterien der optimale Rohwasserentnahmehorizont (niedrigstmögliche Hu-minstoffkonzentration) gewählt. In der Talsperre Fláje könnte die Rohwasserqualität durch Instal-lation eines schwenkbaren Entnahmerohres erheblich verbessert werden. In den Wasserwerken sind die Huminstofffraktionen mit abnehmender Molekülgröße schwieriger zu entfernen. Die relativ niedermolekularen Building Blocks sind die am schwersten entfernbaren DOC-Bestandteile. Auf Grundlage mathematischer Beziehungen zu SAK254 bzw. DOC wurde ein Programm (DOCQuaC – DOC-Quality Calculator) entwickelt, mit dessen Hilfe die Huminstofffraktionen über diese Grundparameter ermittelt werden können. Neben der Fraktionsquantifizie-rung besteht im Programm die Möglichkeit zur Berechnung der Eliminierungsleistung, so dass beispielsweise nach der Durchführung einer Maßnahme zur Verbesserung der DOC-Entfernung eine unmittelbare Aussage über den Effekt auf die Fraktionen vorliegt.For the last 15 years a change of Dissolved Organic Carbon (DOC) has been taking place in surface waters of Middle European Highlands. The degree of this increase is regionally dependent. The reasons as well as the consequences of this development are of high complexity. The changes are expressed in an increase of middle DOC values and, additionally, an increase of annual changes. Reservoirs, used for drinking water production, are particularly affected, because the heightened DOC content increases the costs for drinking water treatment, and currently it is not possible to maintain a good drinking water quality. The main DOC source are peat bogs, situated in the catchments. The cause of the increasing DOC output from peat bogs are very complex and contain changes as well in climate as in land use. The aim of this presented dissertation was to gain more information about the character of DOC, so that those fractions can be determined which are problematically to remove inside the waterworks. On that base it should be possible to find some starting points for more regulating measures. The analytical characterisation was carried out by the help of a LC-OCD-System (Liquid Chromatography – Organic Carbon Detection), exemplary for the reservoir systems Muldenberg, Carlsfeld (Western Ore Mountains) and Fláje (Eastern Ore Mountains, Czech Republic). Although the DOC concentrations are very different in the reser-voirs, it was always dominated by humic substances, namely as well in the tributaries, as in the raw and treated water. Thus changes in the DOC concentration are due to changes in the concen-tration of humic substances. In spring and summer occur the highest concentrations of humic substances in the tributaries. Low concentrations are linked with frost in winter or dry periods in summer. In the reservoirs in summer a stratification of humic substances shapes up, with lower concentration near the water surface (caused by photolytical degradation) and accordingly higher concentration near the ground (layering of influxes). Distribution in winter only depends on the layering of the influxes. In summer the concentration of Building Blocks (humic substance hydro-lysates) is opposite to that of humic substances, because of the creation of Building Blocks at the photolytical degradation. During circulation the concentration of all humic substance fractions are equal in each reservoir layer. In the reservoirs Muldenberg and Carlsfeld, a further optimisation of the raw water withdrawal horizon is not possible. In the reservoir Fláje the raw water could be much improved by installing a movable withdrawal device. With decreasing molecular size the elimination of the humic fractions gets more difficult in the waterworks. Most difficult to eliminate are Building Blocks. On the basis of the mathematical cor-relation between humic fractions and the SAC254 and DOC a program (DOCQuaC – DOC-Quality Calculator) has been developed, which enables die calculation of humic concentrations by enter-ing these general parameters. In addition to the calculation of the concentrations it is possible to calculate the elimination capacity for the humic fractions. Thus the effects of measures on the humic fractions, which could be done for optimisation of the elimination capacity, can be imme-diately observed.
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Gu, Yesong. "Purification techniques for human growth hormone (hGH) and an hGH antagonist." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1174400198.
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Tang, Bing. "Applications of Solid-Phase Microextraction to Chemical Characterization of Materials Used in Road Construction." Doctoral thesis, Stockholm : Division of Highway Engineering, Royal Institute of Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4637.
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Rajoelina, Jasmin Armand. "Essai de purification et de caractérisation d'un facteur de croissance de petit poids moléculaire à partir de fractions sanguines humaines (FC-PPM)." Nancy 1, 1987. http://www.theses.fr/1987NAN10354.
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Capron, Isabelle. "Traitement thermique des moûts de fermentation et organisation moléculaire du xanthane, conséquences rhéologiques." Rouen, 1996. http://www.theses.fr/1996ROUES021.
Full textAbstract:
Le xanthane est un exopolysaccharide anionique de fermentation. Sa conformation semi-rigide et sa forte masse moléculaire en font un agent largement utilisé dans de nombreuses applications pour ses qualités épaississante et viscosifiante notamment. Ces caractéristiques sont gouvernées par une transition conformationnelle, fonction essentiellement de la salinité et de la température. L'étude de ces paramètres en diffusion de la lumière, viscosimétrie, couplage chromatographie d'exclusion stérique / diffusion de la lumière et microscopie à force atomique principalement a permis de mettre en évidence une organisation en double hélice de la molécule native, celle-ci pouvant subir une dénaturation à une température suffisante accompagnée d'une dissociation irréversible en milieu dilué. La renaturation s'effectue par contre selon un processus intramoléculaire montrant un repliement antiparallèle de la chaîne. En régime concentré, l'existence d'interactions intermoléculaires renforcées par l'apparition de mésophases à une concentration suffisante permet d'accéder aux caractéristiques d'un gel faible des 7g/l dans NaCl 0,03M. Une étude de montée-descente en température a également montré la formation de telles liaisons intermoléculaires lorsque la transition conformationnelle a pu s'effectuer. Une simulation des phénomènes intervenant au cours du traitement thermique de post-fermentation a été effectuée et suivie en rhéologie sur un ferment brut. Cette étude a permis de déterminer les raisons de la non dissociation de la molécule de xanthane lors du traitement thermique de post-fermentation malgré la température imposée (T > Tm) par des effets de concentration. De même, l'augmentation de la viscosité observée lors de ce traitement est attribuée à la formation d'associations intermoléculaires lors de l'ouverture des chaînes latérales et à la présence de protéines dans le milieu impliquant des domaines hydrophobes.
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Lapp, Alain. "Synthese, conformation et interactions de molecules lineaires et ramifiees de polydimethylsiloxane : mise en evidence de lois d'universalite." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13108.
Full textAbstract:
Synthese du polydimethylsiloxane etudie et etude de l'hydrosilation se produisant au cours de la reticulation en solution semidiluee, relation entre la longueur de correlation et la concentration. Interactions a trois corps dans le styrene, solvant theta du pdmsi
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Pelisson, Bernard. "Vieillissement du polyamide-11 en présence d'huiles brutes et en température." Rouen, 1986. http://www.theses.fr/1986ROUES021.
Full textAbstract:
Etat des connaissances sur le polyamide-11 et les RILSAN commerciaux; vieillissement modélisé du RILSAN; vieillissement accéléré du RILSAN; analyse de gaines internes vieillies sur site d'exploitation
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Duvic, Bernard. "Purification et etude de la proteine de transport de la 20-hydroxyecdysone chez un insecte : locusta migratoria." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13160.
Full textAbstract:
La purification du transporteur est realisee a partir d'hemolymphe par differentes techniques (coagulation a temperature ambiante; chromatographie sur colonne echangeuse d'anions; chromatographie sur colonne de gel permeation; hplc sur phase echangeuse d'anions). Le transporteur est une glycoproteine acide (pi=5,6) de 280 kda. C'est un homodimere a 2 sous-unites de 140 kda dont la sequence n-terminale a ete determinee. Un polyserum de lapin et 2 anticorps monoclonaux de souris ont ete obtenus et permettent un dosage elisa du transporteur. Des dosages chez l. M. Montrent que le transporteur et l'ecdysone varient dans le meme sens. L'injection massive d'ecdysone suggere une synthese du transporteur sous le controle des ecdysteroides
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Roure, Isabelle. "Rhéologie et dimensions des chaines du hyaluronane en solution." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10227.
Full textAbstract:
Dans ce travail, nous avons cherche a relier le comportement rheologique des solutions de hyaluronane (ha) et de son derive reticule le hylane, aux dimensions des chaines. Dans une premiere partie nous avons etudie l'influence de la force ionique sur la viscosite des solutions et sur la separation en masse molaire par chromatographie d'exclusion sterique (sec). Nous montrons que la contribution du ha a la force ionique correspond a celle d'un electrolyte simple. L'obtention a de faibles forces ioniques d'un maximum dans la courbe viscosite reduite en fonction de la concentration en polymere a ete interpretee a partir des theories des polyelectrolytes. Ceci nous a permis de mieux comprendre le role des interactions electrostatiques. L'utilisation de la sec couplee a trois detecteurs en fonction de la force ionique de l'eluant nous a permis de definir l'influence de la force ionique sur la separation, de valider la loi d'etalonnage universelle. La comparaison des variations experimentales de et rg en fonction de la masse obtenues par sec avec celles obtenues theoriquement permet de determiner la longueur de persistance intrinseque du ha egale a 70a. Dans une deuxieme partie, nous avons montre que la variation de la viscosite specifique des solutions de ha suivait une loi en c dans le regime dilue et en cm dans le regime semi-dilue. A partir de la variation des viscosites avec la temperature nous avons caracterise trois domaines dans le regime semi-dilue. Le domaine intermediaire est caracterise par une diminution de l'influence de la temperature sur la viscosite. Nous avons attribue cette diminution (qui est fonction du produit cm) a une augmentation de la rigidite des chaines de ha. Enfin, nous montrons dans la derniere partie que le comportement rheologique du hylane en solution correspondrait, s'il etait possible de le synthetiser, a celui d'un ha de tres forte masse molaire, conditions qui favorisent particulierement les proprietes viscoelastiques.
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Vandevelde, Margez Marie-Colette. "Contribution à l'étude physicochimique d'un polyélectrolyte naturel : la gomme arabique exsudat d'acacia Sénégal." Rouen, 1986. http://www.theses.fr/1986ROUES007.
Full textAbstract:
Méthodologie de caractérisation de la gomme arabique: chromatographie d'exclusion de différents nodules d'acacia Sénégal et fractionnement de la gomme arabique; interactions de petits cons (colorants) avec la gomme arabique
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Bopape, Dineo Anna. "Fractionation of natural organic matter (NOM) in water using prepared porous silica based materials as size exclusion (SEC)/GEL permeation chromatography (GPC) stationary phases." Diss., 2017. http://hdl.handle.net/10500/23999.
Full textAbstract:
Natural organic matter (NOM) is a diverse blend of decomposed animal and plant material
found in different natural water sources. Due to its large and complex structure, NOM is
difficult to both remove and characterize in water. Therefore, there is a need to separate
NOM into its components before it can be characterized. The aim of this project was to
fractionate NOM through a novel size exclusion chromatography (SEC) composite (poly
(styrene-divinyl benzene) (PS-DVB) and Polysilsesquioxane (PSQ)) packed column. Raw
and final water samples from Mid-Vaal (MV), Olifantspoort (LO), Mtwalume (MT) and
Preekstoel (P) were investigated. Poly (styrene-divinyl benzene) (PS-DVB) and
polysilsesquioxane were both synthesized and optimized at various temperatures,
compositions and time periods. An end-capping material such as hexamethyldisilizane
(HMDS) was added on the PSQ to prevent active silanol groups on the polysilsesquioxane
(PSQ) from reacting with active sites of NOM (our analyte). The E-PSQ (end-capped PSQ)
and PS-DVB materials were packed in eight different SPE cartridges first, before the
materials could be packed in the SEC column. This packing was done to check for the best mass composition of the E-PSQ and PS-DVB. From the obtained SPE results, both the EPSQ
and PS-DVB were packed in one SEC/GPC column at a ratio of 1:1 in order to form
the composite hybrid material. The packed SEC column was connected to an HPLC
instrument and various column efficiency tests were evaluated. The results for the test of
interactions with acidic compounds implied that the column can be used for the acidic
analytes such as those forming NOM composition (humic acids, fulvic acids) and the
column had minimum silanol groups. For hydrophobic interactions the stationary phase
strength was different to that of the commercial columns and it could selectively elute
molecules based on their different masses. The steric selectivity test showed that the
stationary phase could separate and distinguish between molecules with similar
hydrophobicity and structure but different shapes (o-terphenyl and triphenylene). The
Hydrogen bonding capacity (HBC) test showed that the column had minimum silanol
groups and the end-capping was successful on the E-PSQ.
After fractionation of all the water samples, the MT raw showed NOM peaks around 1.8
mins, 3.4 mins and 5.3, and the final showed NOM peaks around 1.8 mins and 5.5 mins.
The Mid-Vaal (MV) raw and final samples shows NOM peaks at around 1.8 mins and 6
mins. The Preekstoel (P) final water had one NOM peak at around 1.8 mins and raw
samples had two NOM peaks around 1.8 mins and 6 mins.Chemistry
M. Sc. (Chemistry)
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Ching-Lung, Lin, and 林清隆. "Analysis of Synthesized Photoelectronic Polymer by Gel Permeation Chromatography." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/mw5324.
Full textAbstract:
博士國立臺北科技大學
工程科技研究所
103
The research project of this thesis is mainly studied the synthesis of Photoelectronic Polymer and its application on polymer solar cells. In the synthesis section, we divided into two topics to discuss. For the first topic, we have synthesized polymer, poly [2-methoxy 5-(2-ethylhexoxy)-1,4-phenylenevinylene] MEH-PPV, with varied molecular weights via controlled polymerization conditions. For the second topic, we changed the alkyl group of thiophene 3 position to synthetize 4 different poly(3-alkylthiophene)(P3AT) with poly(3-hexyl thiophene) (P3HT), poly(3-octyl thiophene) (P3OT), poly(3-decanal thiophene) (P3DT),and Poly (3- dodecylthiophene-2,5-diyl) (P3DDT). We used gel permeation chromatography(GPC) to study the Photoelectronic Polymer properties。 All effects of molecular weight (Mw) and polydispersity (PDI) on emission properties and the morphology of polymer film are discussed by the measurements of Gel Permeation Chromatography (GPC), atomic force microscopy (AFM) and scanning electron microscopy (SEM)。
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Bhoolia, Deena. "Preparation of ribsomal subunits by gel filtration." Thesis, 2016. http://hdl.handle.net/10539/20684.
Full textAbstract:
A Oiss{!y'tation $uhm'itted in fulfilment
of the r~;~airements, for' the degree of
f·1aster· oi~'j Science at the University
of the ~titwatersrand '
Juhanoasbul"g
January 1991An attempt was made to separate ribosomal subunits by gel filtl'ation on Trisacryl GF2000 and Sepharose 4B. Trisacryl GP~2000,a sYllthet'ic gol, , separated rat .ljver rlbosonal subunits orl 'f~'135,em column with a resolution of ""Or3, resulting 'in <'1" 60 rJ impm''ity 'of each of the \~ subunits. subunits" were not resolved. Sepharose 4131 an agarose based gol, separated " the subunits by adsorpttcn chromatography rathr.r than 'i>.V () Q ':) At 4°C, the 405 .subunf ts were eluted with a kd () ruO,:~9( but the GOrf' $ubud"its adsorbed to th~.'g,~Jl and were eluted I; /) when the temperature of "the column was increas~d to 250C..3SoC. (' ,. ('-. This edsorpt ion phenonenon seems to b{~ tl propert~ of a 11 agllrose -: \') ~\:; based gels studied here, includ'ing Sepharose 2.B and .seph'ato~eoBt arid is exc 1us iva to !,mamm'i'lan r ibosOIntrt subuni ts • Anal,ys1S 0'(" the , u subunits by in vitro r14C]polypheny1alanine sy'nthes'is showed OCI " ,,'c. /\ I 7', " diff'erence 'in the act lvtt ies of dbosoma'J ~ubunH~ p~epdrf#d by ;/'/ ' grndient centrifugation or by 5epharos,e cni"OmatogNPPY;' Analy~ii ~~of " (~ (( the subunits by ~crylamidec'ugarose coU)po5it~) gs1s resulted ,in the '/ resolution ,.:n"f subunits isolated fr'oill lower organisms in o II non-denaturlnq !Jcl systems and SI,lbut1its from m«mm~nan'tissue in II /'\';1 Ga'! f'iltrat'ion does tyffer a 5t!i:l;~'ble metrKld'¥or the pr~p;n~¥tiol1of <::) . I \) \\ I) ribosoma 1 'subunits I but only' if 'the act~orption JH'OrJ&~"t'Jo,s of ,) (,) ':' o ,1) ,{
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Yu-ChaoKao and 高于超. "Interactions between Poly(N-vinylformamide) and Sodium Dodecyl Sulfate Studied by Gel Permeation Chromatography with Online Multi-Angle Light Scattering." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/84202625719611700176.
Full textAbstract:
碩士國立成功大學
化學工程學系碩博士班
100
The novel method to characterize the polymer-surfactant interaction is using gel permeation chromatography with online multi-angle laser light scattering, differential refractometer, and UV/Visible detector. In this study, the interaction between poly(N-vinylformamide) (PNVF) and sodium dodecyl sulfate (SDS) under several SDS concentrations has been investigated by using this technique to confirm the influence of SDS bound into the PNVF/SDS complex on the molecular shapes of PNVF. The application of both Hummel-Dreyer method and multi-component light scattering principle provides much useful information concerning the determinations of the binding ratio (the amount of SDS bound to PNVF), the z-average radius of gyration of PNVF/SDS complexes (Rz), and the molecular mass of PNVF/SDS complexes (Mw,PS) and the PNVF itself within the PNVF/SDS complexes (Mw,P). From the measurements of the molecular mass of PNVF in the PNVF/SDS complexes at different SDS concentrations, the results show that the Mw,P increasing with increasing SDS concentrations between cac and cmc. It indicates that a significant intermolecular association between cac and cmc in PNVF/SDS system, even when the PNVF concentration below the critical overlap concentration (c*).
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Cheng, Han-Ling, and 鄭涵玲. "Determinations Of Liposome Size And Dendrimer Molecular Weight By Using Gel-Permeation Chromatography Coupled With Differential Viscometer And Light Scattering Detector." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/03200239811042951866.
Full textAbstract:
碩士國立中正大學
化學暨生物化學研究所
100
Gel-Permeation Chromatography (GPC) is the technique which can measure the molecular weight (M.W.) and polydispersity index (PDI) of polymer using size exclusion mechanism. GPC method with multi-functional detectors including low-angle laser light scattering (LALLS), right-angle laser light scattering (RALLS), differential viscometer (DV) and refractive index (RI) enables to determine the particle size of different macro-molecules in solution and to calculate the absolute molecular weight without using any polymer standards. First, we use pullulan standards (5k, 10k, 20k, 50k, 100k, 200k, 400k, and 800k) to carry out universal calibration (UC) method to establish the relation curve using GPC (Viscogel) column, which shows the linear relation of the molecular weight versus retention volume to confirm the size ranges of proper exclusion. Next, the chromatograms acquired with the detection combinations of LALLS, RALLS, and DV along with RI detector are able to compare the determination bias of pullulan M.W. between using Viscogel column and guard column. One also can employ the above four-detector methods to estimate the hydrodynamic radius (Rh) and radius of gyration (Rg) of macro-molecules. The relative error of pullulan 400k M.W. determination differences between using three detection methods ("RI+RALLS+DV", "RI+RALLS", "RI+LALLS") are small (~3%). The least determination measurement error is found using "RI+RALLS+DV" detection method because of better signal sensitivity of light scattering collected at the right angle and angular correction with viscometry measurement. We can also use the GPC method with two static light scattering detectors collecting at right-angle and low-angle, respectively to measure liposome particle size. The Rg of liposome is determined as 44-48 nm using GPC with light scattering detectors which is verified by comparing the Rh of liposome measured as 55 nm with dynamic light scattering method and the particle size of 47 nm imaged with transmission electron microscope. Finally, we use characterized particle size and M.W. data of polyamidoamine dendrimer standards to confirm the scaling relation of RALLS intensity/ concentration versus M.W. Although dendrimer M.W. cannot be determined because of lacking proper instrument constant calibration. We also use Einstein viscosity equation to confirm the relation of intrinsic viscosity versus dendrimer generations. Further study of dendrimer reaction kinetics in different generations can be investigated by using the above scaling relations.
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Wong, Michael. "Molecular Weight Limit Identified for the Synthesis of Externally Initiated Poly(3-hexylthiophenes) and Further Macrocyclic Constructions." Thesis, 2013. http://hdl.handle.net/1807/35147.
Full textAbstract:
Externally initiated o-tolyl initiated poly(3-hexylthiophene) (P3HT) was synthesized according to Grignard metathesis polymerization at varying chain length to compare number average molecular weights (Mn) obtained by gel permeation chromatography (GPC) and 1H NMR end group analysis. The extent of overestimation by GPC (1.3) was determined to be lower than previously reported for low Mn polymers. However, an apparent GPC quantification limit was observed as NMR Mn correlated well to predicted results. Static light scattering studies on high Mn polymers provided evidence that the true molecular weight was more similar to GPC-derived Mn. Despite nearly 100% external initiation efficiency, at a certain Mn limit new uninitiated chains may be synthesized. It is suggested that the synthesis of externally initiated P3HT should be limited to Mn below 40 kDa to ensure fully externally initiated chains. A proposal for the synthesis of externally initiated macrocyclic P3HT will also be discussed.
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Nepokojová, Tereza. "Modulace interakcí interleukinů a jejich receptorů." Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-435991.
Full textAbstract:
Scaffolds are proteins with high conformational stability, allowing us to implement multiple mutations into specific parts of the protein. Even with these mutations, the structural integrity of the protein is maintained as well as its physical-chemical properties. These mutations give the specific scaffold new properties. In most cases it is the binding specificity towards previously chosen target. The biggest advantages of scaffolds are their small size, stability, low-cost manufacturing, and easiness of preparation. Scaffold utilized in this thesis is unique for having two binging surfaces designed on which it can be mutated. Each of those two surfaces can be separately mutated to develop a binging site for two different proteins. In our case these mutations led to binding two nonidentical receptors of a human cytokine. Mutations are made with a use of yeast display, one of the methods of directed evolution. The main focus of this thesis is changing an expression system of the binding proteins from the yeast system to a bacterial one, their production and purification followed by characterization of those binding proteins using biophysical methods. These methods were used to evaluate structural and thermal stability, and binding affinity to both receptors of the beforementioned binding proteins....
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Μοσχοπούλου, Ελένη. "Μελέτη μιγμάτων αλειφατικών/αρωματικών πολυεστέρων." Thesis, 2011. http://nemertes.lis.upatras.gr/jspui/handle/10889/4481.
Full textAbstract:
Αντικείμενο της παρούσας διατριβής αποτέλεσε η μελέτη μιγμάτων αλειφατικών/αρωματικών πολυεστέρων. Αρχικά υπήρχε η πρόθεση να επικεντρωθούμε στη μελέτη της βιοαποικοδόμησης μίγματος ενός αλειφατικού και ενός αρωματικού πολυεστέρα. Για τη διερεύνηση όμως της αναμειξιμότητάς τους εστιάσαμε στην έμμεση μελέτη του μοριακού προσανατολισμού μονοαξονικά εφελκυσμένων μιγμάτων αλειφατικών/αρωματικών πολυεστέρων, με τη χρήση πολωμένων φασμάτων δόνησης. Πιο συγκεκριμένα, εξετάστηκε η σύγχρονη παρουσία σ’ ένα μόνο πολωμένο φάσμα Raman της μη-συμβατικής συμπεριφοράς της δόνησης τάσης της χαρακτηριστικής ομάδας του καρβονυλίου (C=O) των αρωματικών πολυεστέρων με την αντίστοιχη συμβατική συμπεριφορά της ίδιας ομάδας των αλειφατικών πολυεστέρων. Μετά από πολλές προσπάθειες διαφόρων παρεμφερών μιγμάτων στα οποία παρουσιάστηκαν διάφορα προβλήματα, κυρίως αναμειξιμότητας, καταλήξαμε στο μίγμα του βιοαποικοδομήσιμου αλειφατικού πολυεστέρα L-PLA με τον αρωματικό πολυεστέρα PBT. Παρασκευάστηκαν φιλμ των ομοπολυμερών L-PLA και PBT καθώς και του μίγματος L-PLA/PBT, με ανάμιξη των συστατικών σε τήγμα και στη συνέχεια μορφοποίησή τους σε υδραυλική θερμοπρέσα. Για τον προσδιορισμό των θερμικών ιδιοτήτων των υλικών χρησιμοποιήθηκε η τεχνική Διαφορικής Θερμιδομετρίας Σάρωσης (DSC). Δοκίμια των ομοπολυμερών και του μίγματος εφελκύστηκαν μονοαξονικά σε θερμοκρασίες μεγαλύτερες από τη μετάβαση υάλου τους και ο προσανατολισμός τους εκτιμήθηκε με τη χρήση πολωμένων φασμάτων Raman. Σε κάθε περίπτωση, επειδή παρά τις πολλές προσπάθειες δεν ήταν δυνατό κυρίως και πάλι λόγω προβλημάτων αναμειξιμότητας να συνεχιστεί μια τέτοια μελέτη και στο επίπεδο της βιοαποικοδόμησης ενός αλειφατικού και ενός αρωματικού πολυεστέρα, αποφασίσαμε να συνεχίσουμε με ένα αναμείξιμο σε κάθε αναλογία μίγμα, ενός βιοαποικοδομήσιμου και ενός μη-αποικοδομίσιμου πολυμερούς. Το μίγμα αυτό των πολυμερών ήταν το PCL/PVC με το οποίο και συνεχίστηκε και ολοκληρώθηκε η παρούσα διατριβή εξειδίκευσης.
Το ενδιαφέρον επικεντρώθηκε στη μελέτη μιγμάτων PCL/PVC διαφόρων συστάσεων, δύο πολυμερών τα οποία είναι αναμίξιμα σε όλο το εύρος των αναλογιών τους. Το ομοπολυμερές του αλειφατικού πολυεστέρα PCL και τα μίγματα που προέκυψαν μελετήθηκαν ως προς τις θερμικές τους ιδιότητες και χαρακτηρίστηκαν φασματικά με Raman. Επιπλέον, επιχειρήθηκε η μελέτη της βιοαποικοδόμησης τόσο της PCL όσο και των μιγμάτων της με PVC, μετά από εμβάπτιση σε φυσιολογικό ορό για χρονικό διάστημα άνω των 3 μηνών. Για τον προσδιορισμό των θερμικών ιδιοτήτων των μιγμάτων PCL/PVC και του ομοπολυμερούς PCL χρησιμοποιήθηκε η τεχνική DSC, στη συνέχεια χαρακτηρίστηκαν με τη δονητική φασματοσκοπία Raman ενώ ακολούθησαν πειράματα Χρωματογραφίας Διαπιδύσεως μέσω Πηκτής (GPC) και Δυναμικής Σκέδασης Φωτός (DLS) ώστε να προσδιοριστεί η βιοαποικοδόμηση των υλικών. Η βιοποικοδόμηση των PCL/PVC και κατ’ επέκταση της PCL μελετήθηκε υπό διαφορετικές συνθήκες (θερμοκρασίας, χρόνου, συγκέντρωσης) και σε διαφορετικό βαθμό.The aim of this dissertation was the study of aliphatic/aromatic copolyesters. At the beginning, the main purpose was to investigate the biodegradation behavior of an aliphatic/aromatic polyester blend. In order to examine the miscibility of the two polymers comprising the blend we have studied the molecular orientation of melt blends utilizing polarized vibrational spectroscopy. After plenty of essays on resembling blends and due to the problems that we have faced (mainly miscibility problems) we decided to study the polymer blend of the biodegradable aliphatic polyester Poly(L-lactic acid) (L-PLA) and the aromatic polyester Poly(butylene terephthalate) (PBT). In particular, the interest centered to the peculiar and unexpected behavior of the C=O stretching carbonyl Raman band of the aromatic polyesters (in case PBT) comparing to the corresponding conventional behavior of the aliphatic polyesters, (in case L-PLA). L-PLA/PBT blends were prepared through reaction extrusion (melt mixing). Films prepared by melt pressing have been uniaxially hot drawn. Polarized laser Raman spectroscopy has been used to estimate the molecular orientation of drawn films of L-PLA and PBT homopolymers and L-PLA/PBT polymer blends. The crystallization behavior of the samples was investigated by using a differential scanning calorimeter (DSC). Finally, the polymers L-PLA and PBT have found to be partially miscible so we took the decision of studying another totally miscible blend consisted of PCL and PVC, a mixture of an aliphatic biodegradable polyester and a non-biodegradable thermoplastic polymer. Blends of PCL and PVC are under development with various potential applications in view, including controlled delivery of agrichemicals, and it is important to investigate their biodegradation behavior. The thermal properties of the homopolymer PCL and PVC blends were investigated under nitrogen by using DSC. Samples of the homopolymer PCL and PCL/PVC blends were placed in glass bottles with serum for more than 3 months. Raman Spectroscopy, Gel Permeation Chromatography and Dynamic Light Scattering have been used to estimate the biodegradation of the samples.