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Mashamba, Mulalo Gift. "Process potentiometric sequential injection titrations." Pretoria : [s.n.], 2001. http://upetd.up.ac.za/thesis/available/etd-11212005-093416/.
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Rajantie, Hanna Katarina. "Electrochemical titrations with dual microband electrodes." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272111.
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Sohail, Assra. "An investigation into the use of mass for manual and automatic titrations." Thesis, University of Salford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491253.
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The use of constant boiling hydrochloric acid as a primary acidimetric standard has been reviewed and investigated. Although this material was first proposed as a standard in the 1930's, it has not been used extensively. It has been established that, using ground glass joint glassware, constant boiling hydrochloric acid is very easy to prepare. It is also very stable and easy to use. It makes an excellent primary acidimetric standard. It is by far the best strong acid standard.
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Santos, Marcos Alves dos. "Titulações potencio-condutimétricas simultâneas: método, programas para simulação e análise de dados e exemplos reais de aplicação." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-08112010-091604/.
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A despeito dos avanços instrumentais, as titulações continuam sendo largamente aplicadas em laboratórios de química analítica. Seu amplo uso está relacionado com a boa exatidão em aplicações bem estabelecidas e freqüente indicação como método de referência (p. ex., farmacopéias), equipamentos simples, comuns e de custo reduzido, consumo moderado de tempo e de reagentes. Entre as técnicas de titulação, destacam-se as potenciométricas (TP), empregadas universalmente para a quantificação de um ou mais componentes ácidos ou básicos em soluções aquosas ou não aquosas, possibilitando ainda determinar as constantes de dissociação de ácidos e de protonação de bases. Na análise de dados de TP são, via de regra, empregados os métodos clássicos (derivadas), porém, para sistemas compreendendo componentes multiprotonáveis, as inflexões das curvas de titulação deixam ser nítidas, especialmente em baixas concentrações. Nestas condições desfavoráveis, ainda assim podem-se obter resultados satisfatórios recorrendo a métodos de linearização das curvas ou analisando os dados por regressão não linear (RNL), facilmente implementáveis em computadores, hoje disseminados nos laboratórios. Outra técnica clássica para acompanhamento de titulações é a condutimétrica (TC), menos utilizada que a TP nos dias atuais, salvo para ácidos ou bases muito fracas, servindo para prover dados complementares em estudos de formação de complexos ou na caracterização de amostras ambientais. Tipicamente os pontos estequiométricos coincidem com a intersecção de segmentos de reta. Para amostras muito diluídas, com sistemas multipróticos ou com elevada concentração de eletrólitos em relação às espécies tituladas, a interpretação gráfica fica dificultada e a precisão decai. Pesquisas recentes mostraram que é possível aproveitar informações obtidas por TP para alimentar modelos de regressão não linear de TC e, assim, obter informações mais completas das amostras estudadas. No presente trabalho, avançou-se nesta linha criando programas computacionais para a análise simultânea de dados obtidos por TC e TP, empregando o método de RNL e minimizando os desvios (ou o quadrado dos desvios) dos dois conjuntos completos de dados para prover caracterização mais completa das amostras e melhoria na precisão dos resultados. Um programa de simulação de dados de TC e TP das mais diversas combinações e concentrações de sistemas ácido-base, com recursos para acrescentar erros aleatórios às variáveis simuladas, foi também desenvolvido. Permitiu verificar a validade e potencialidade do método da TPC-RNL e aperfeiçoar o programa de análise simultânea de dados. O programa de TPC-RNL foi aplicado inicialmente à re-avaliação de dados de titulações de água de chuva anteriormente coletadas e analisadas por outro colaborador do grupo. Como exemplo de aplicação original a amostras reais difíceis tanto para a TC como a TP isoladamente, determinou-se, por TPC, baixas concentrações de ácidos orgânicos de baixo peso molecular em amostras obtidas do produto de oxidação acelerada do biodiesel. Os resultados se mostraram compatíveis com os obtidos por outro pesquisador que recorreu à eletroforese capilar, sendo que o pH, a condutividade e a força iônica das amostras também foi reproduzida pelo programa Peak Master alimentado com as concentrações ajustadas por RNLDespite all the advances in instrumental techniques, titrations are still widely applied in analytical chemistry laboratories. Its widespread use is associated with good accuracy, well established applications, simple, readily available and low cost equipment, moderate consumption of time and reagents and frequent indication as a reference method (eg., Pharmacopoeias). Potentiometric titrations (PT) outstands among other techniques, being universally used for the quantification of one or more basic or acidic components in aqueous or non aqueous samples and enabling further determination of the dissociation constants of acids and bases. Data analysis of PT with the glass electrode is typically done by finding the inflections of the curves with help of simple derivatives. However, PT curves of systems with multiprotonable components, specially at very low concentrations, fail to show sharp inflections. Under such unfavorable conditions, satisfactory results can still be obtained by using curve linearization methods or nonlinear regression (NLR) methods, now at the reach of every laboratory computer. Another classic technique for following titrations is conductivity (CT), less used routinely than PT nowadays except for very weak acids or bases, but still valuable as a complementary technique in equilibrium studies of complex formation or for the characterization of environmental samples. The stoichiometric points of simple CTs are found at the intersection of line segments. For very dilute samples or for multiprotic systems or with high concentrations of electrolytes compared to the species to be titrated, the graphical interpretation becomes difficult and the accuracy declines. Recent research has shown that it is possible to harness information obtained by PT to render non-linear regression models of CT solvable, thus extracting more complete information of the samples. This dissertation is devoted to the development and evaluation of software for the simultaneous analysis of data from CT and PT gathered together in the laboratory or by simulation, using the method of NLR with minimization of the weighted deviations (or their squares) of the two full data sets to provide more complete characterization of the samples and to improve the precision of the results. A simulation program for generating CT and PT curves for freely combined acid-base systems over a wide concentration range, with features to add random errors to the simulated variables was also developed. The simulator was used to evaluate the validity and potentiality of the PCTNLR method and improve the software of simultaneous data analysis. The program of PCT-NLR was applied firstly to the re-evaluation of data from titrations of rainwater collected and analyzed previously by another contributor to the group. As an original application example to real samples that are difficult for CT or PT separately, low concentrations of organic acids of low molecular weight were determined by PCT-NLR in samples from accelerated biodiesel oxidation tests. The results were consistent with those obtained by another researcher who used the capillary electrophoresis. The pH, ionic strength and conductivity of the samples were also reproduced by the program Peak Master using concentrations adjusted by NLR
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Hill, Gordon Craig. "DNA binding studies of antitumor antibiotics and antitumor anthracene derivatives: Computer simulations and spectrophotometric titrations." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185221.
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Quinocarcin binds to d(ATGCAT)₂ with a preferred direction of 3' and the R configuration at C4 of the drug. A mode of action involving ring opening of the oxazolidine ring to form an iminium ion which can then alkylate the N2 of guanine has been reinforced by the current computer modeling study. The absolute configuration for quinocarcin should be reversed based on the fact that the optical isomer of the structure arbitrarily assigned in the literature forms a much better binding complex to DNA. Anthramycin binds to the 2-amino group of guanine but its mechanism of action proceeds through a neutral imine. The 3' direction is again favored but for this molecule, the preferred configuration is S. This computer modeling study provided a basis for a 2D NMR study which confirmed that anthramycin forms a 3'S adduct when it binds to d(ATGCAT)₂. Bisantrene and R9 are synthetic anthracene derivatives with antitumor activity. Use of UV spectroscopy provided insight into the ability of these compounds to intercalate between the base pairs of double helical DNA. Standard Scatchard plot analysis proved useless in determining the binding parameters. A McGhee-von Hippel equation was able to describe a portion of the data but a smoothing spline function was able to describe the data completely. Naphthyridinomycin studies indicate that it too prefers a covalent adduct in which the direction is 3' and the configuration is R at C7. When the noncovalent drug binds to d(ATGCAT)₂ it may bind with either the C3a face or the C7 face closest to N2 of guanine. Iminium ion mechanisms have been proposed for the binding of naphthyridinomycin to N2 of guanine in the minor groove of DNA and the computer modeling presents evidence to support such mechanisms. Saframycin A binds much better to d(GATGCATC)₂ as a hydroquinone species but the quinone can still bind in the same site. The 3' direction is clearly preferred with the R configuration at C7. The hydrogen bonding network of the hydroquinone is conserved in the noncovalent, iminium ion, and covalent 3'R models after 32 ps of dynamics. Iminium ion mechanisms have been proposed for the binding of saframycin A to N2 of guanine in the minor groove of DNA and the computer modeling presents evidence to support such mechanisms.
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McGrath, Jacqueline. "Advances in Supramolecular Catalysis: Studies of Bifurcated Hamilton Receptors." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/19691.
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Bidentate ligands are a commonly used class of ligands in catalysis that generate highly-active and selective catalysts. Such bidentate ligands, however, often suffer from synthetic challenges, which can be alleviated by the use of simpler monodentate ligands that assemble through non-covalent interactions to mimic the structure of bidentate ligands at the metal center. To produce a strongly assembled catalyst complex, the Hamilton receptor motif was utilized. Hamilton receptors form six hydrogen bonds with complementary guests and have binding affinities for barbiturates of up to 104 M-1 in CDCl3. Complete bifurcation of the Hamilton scaffold produces a modular ligand structure that allows for modification of either end of the supramolecular ligand structure. Similarly, the barbiturate guest can be synthetically altered creating both chiral guests and guests with differing amounts of steric bulk.
Both experimental titration data and density functional theory calculations show that steric bulk discourages binding of the guest while a pre-organized host encourages guest inclusion. Electronic effects on the bifurcated Hamilton system were studied by varying the electron donating or withdrawing ability of the benzamide moiety on the host molecule. Electron withdrawing moieties produce more acidic amide hydrogens on the host which are able to participate in stronger hydrogen bonds with the guest resulting in a stronger host-guest complex. The effects of substitutions on the barbiturate guest were examined as well, and increased steric bulk on the guest resulted in decreased affinities with the host.
The bifurcated Hamilton receptor ligands were examined in the palladium-catalyzed Heck reaction of iodobenzene with butyl acrylate. Pd2(OAc)4 was used as a control and all reaction yields with the diphenylphosphine ligand-stabilized Pd were greater than or equal to those obtained with Pd2(OAc)4 alone. The reaction rates did not correlate with the determined binding constants, suggesting that phosphine substitution on the guest plays a larger role than affinity of the complex for the guest. Reaction temperatures were varied, and at lower temperatures the yields increased implying that the strength of the hydrogen bonds between the metal complex and the guest does play a secondary role in the catalysis.
This dissertation includes previously published co-authored material.
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Sundman, Ola. "Cation adsorption properties of substituted kraft fibres : an experimental and thermodynamic modelling study." Doctoral thesis, Umeå universitet, Kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1891.
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Acid/base and metal ion adsorption properties have been investigated for a range of chemically modified bleached Kraft fibre materials (pulps). The studies were performed via potentiometric titrations, Flame Atomic Absorbtion (and Emission) Spectroscopy, Inductively Coupled Plasma Optical Emission Spectroscopy and Extended X-ray Absorbtion Fine Structure measurements. As a result of a chemical modification procedure, the total concentration of acidic carboxylate groups in the fibre materials ranged between 43 and 590 μmol/g. The preferable surface potential model for modelling the ionic strength dependent acid/base properties of fibre materials with low charge densities, i.e. unmodified fully bleached Kraft fibre materials, was found to be the Basic Stern Model. For fibre materials with high total charge, ≳100 μmol/g, this model resulted in poor fits to data, and for such materials a number of Constant Capacitance Models, one at each ionic strength, must be recommended. With respect to metal ion adsorption, the results have indicated that the unspecific Donnan theory could correctly model the simultaneous adsorption of several metal ions, i.e. K+, Na+, Mg2+, Ca2+ and Cu2+, provided that the salt concentration in the fibre suspension is low. In suspensions of high salt concentration it was, however, found that this very same model strongly underestimated the adsorption of Ca2+ and Cu2+. Here, the Donnan model had to be complemented by specific ion exchange equilibria. These results were corroborated by spectroscopic evidence of specific interactions between Cu2+-ions and fibres. The spectroscopic indication of a complex formed between two fibre surface carboxylate groups and one Cu2+-ion, agree with the specific ion exchange model. It was therefore concluded that specific metal ionfibre interactions cannot be neglected, especially at high salt concentrations. The interactions occurring between the polycation GaO4Al12(OH)24(H2O)127+ and fibre materials were studied by both adsorption and spectroscopic measurements. These indicate that GaO4Al12(OH)24(H2O)127+ is surprisingly stable in fibre suspensions and that intact GaO4Al12(OH)24(H2O)127+- ions are strongly adsorbed onto the fibres. Also for this ion, specific interactions has to be considered, since the strong adsorption registered was too strong to be explained by Donnan equilibria. In the thesis, the stochiometric composition and an equilibrium constant characterising these interactions is presented.
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Halliday, Colin George. "Aspects of photometric titration." Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329513.
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Bowen, Martina E. "I. Use of 9-methylfluorene as an indicator for organometallic titrations II. Synthesis of a branched polyethylene glycol linker for peptide ligands III. Synthesis of a linker for peptide ligands and a study of its pH sensitivity." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/290107.
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This work details the synthesis of some useful organic molecules: (I) 9-Methylfluorene was tested as an indicator in the titration of commonly used organometallic reagents. This indicator is readily prepared in three steps from fluorenone. In THF solution the deprotonated indicator is red and exhibits a sharp endpoint. The highly basic reagents sec-butyllithium and tert -butyllithium can be titrated in ether solution, where the color of the deprotonated indicator is yellow. (II) A branched, polyethylene glycol based linker for peptide ligands was designed and synthesized. The linker needed to be water soluble, to be stable under both acidic and basic conditions, to have amine and carboxyl termini for use in solid phase peptide synthesis, and to have an attachment site for a fluorescent marker. The polyethylene glycol linker was designed with a carboxyl terminus and two amine termini that can be differentially protected to facilitate selective deprotection and reaction with three peptides or two peptides and a fluorescent tag. (III) A molecule containing a linear polyethylene glycol linker with beta-alkoxyamide moiety was synthesized and its pH stability determined using an HPLC method. Stability was assayed in 5 mM buffers at pH 4, 7, and 9 over 24 hours. No decomposition in these solutions was detected. The linker was then subjected to 10 mM acid or base solution and analyzed over 24 hours. Again, no decomposition was observed.
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Fardel, Julien. "Application of thermometric titration methods /." Sion, 2008. http://doc.rero.ch/record/12817?ln=fr.
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Neville, M. D. "The development of titration membrane electrodes." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47202.
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Butt, Michael David. "Macromolecular thermodynamics studied by titration calorimetry." Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/34042.
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This thesis is centred on the use of an isothermal titration microcalori-meter which can measure heat changes of the order of a few microcalories. The calorimeter provides a rapid and convenient method, incorporating a thermodynamic analysis, for estimating enthalpic pairwise interaction parameters, hjj, for solute-j in aqueous solution. Estimates of hjj for three solutes; urea, monoethylurea and hexamethylenetetramine are reported. Comparisons with published estimates of hjj show good agreement, and confirm the importance of the new technology in calorimetry. The critical micellar concentrations (cmc's) of a series of l-alkyl-4-alkylpyridinium halide and bisquaternary ammonium bromide surfactants are reported, using q, heat change on injection, as the reporter. The standard enthalpy of micelle formation is also obtained, directly, from titration experiments. An equation is derived for the standard Gibbs energy of micelle formation, for these compounds. Thus, the standard entropy is calculated and the driving force (enthalpy or entropy) for micellisation, of these surfactants, is identified. Injection of small aliquots of fusogenic agents (the dianions of dipicolinic acid and sodium sulphate) into aqueous solutions of dioctadecyldimethyl-ammonium bromide (DOAB) vesicles is endothermic at 50 Celsius. For solutions containing greater than equimolar ratios of DOAB and fusogenic agent, the injection process is effectively athermal. The patterns of enthalpy change are attributed to vesicle-dianion interaction (exothermic) and headgroup dehydration (endothermic). Other effects such as the presence of buffer and the interaction of DOAB with halide monoanions are also discussed. Binding of the substrate, chloramphenicol (CM), to the enzyme, chloramphenicol acetyltransferase (CAT), is exothermic. Calorimetric measurements of a series of injections of CM into CAT, and subsequent analysis, yield the binding constant, number of binding sites per macromolecule (enzyme) and the standard enthalpy of binding for the interaction. These three parameters are presented, together with the standard entropy and standard Gibbs energy of binding.
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Motara, Hasina. "Isothermal titration calorimetric studies of complexation reactions." Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/10779/.
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The objective of this work has been to study the binding of metal ions to complex ligands expressing two or more metal binding sites, in terms of the thermodynamics of the binding events, and to use this information to contribute to the understanding of both the metal binding processes and the properties of the metal/ligand complexes. Two ligands have formed the basis of the study, one a naturally occurring enzyme and the other a newly synthesised ligand with two distinct binding sites (to form supramolecular complexes). The principle technique used to determine thermodynamic parameters has been isothermal titration calorimetry (ITC). The first system studied involved the enzyme β-lactamase II from Bacillus cereus 569/H/9 (BcII). The binding of zinc (II), cobalt (II) and cadmium (II) was investigated in aqueous solution at pH’s from 5.2 to 7.2. By using three or more buffers at each pH it has been possible to determine not only the binding constants of the metal ions at these pH’s but also the molar enthalpies of binding (and hence molar entropies). In addition, the dissociation of hydrogen ions from the enzyme on metal binding was also observed. In the case of all three metal ions, one metal ion per enzyme appears to bind at low pH and two metal ions at high pH (within the pH 5.20-7.20 range). In the case of zinc and cobalt ions two metal ions seem to bind per mole of enzyme in a cooperative mechanism. In contrast two cadmium ions appear to bind to the active sites of the enzyme non-cooperatively. For all three metal ions, models have been developed to describe the two binding sites and the sources of H+ ions that dissociate on metal ion binding. The second system studied involved the supramolecular synthesised ligand bipy-aza-crown-4. This ligand has two metal binding sites, one at the 2,2-bipyridine and the other at the aza-crown-4. The objective was to compare the way copper (II) binds in acetonitrile solution with the way in which the copper (II) complex with this ligand is crystallised from methanol solution with progressively increased copper (II) concentration, as revealed by single crystal x-ray diffraction. Smaller ligands that represent the two individual complexation regions of the synthesised ligand were also used for comparison. Both ITC and solution spectroscopic measurements were used to compare the binding model that was proposed in methanol solution. It was demonstrated in acetonitrile solution that copper (II) binds to the 2,2-bipyridine site first in a 1:2 (Cu2+:L) ratio, then binds to the aza-crown site in a 1:1 (Cu2+:L) ratio . So it was demonstrated that the overall stoichiometric ratio of copper ion to bipy-aza-crown-4 in the fully formed complex is 3:2 (Cu2+: L). Possibly the main conclusion drawn is that the order in which the binding sites are occupied in acetonitrile solution is different to that in which they are occupied in methanol.
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Ebert, Margaret S. (Margaret Sarah). "Molecular titration by MicroRNAs and target mimic inhibitors." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61886.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2010.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
MicroRNAs (miRNAs) are short, highly conserved non-coding RNA molecules that repress gene expression in a sequence-dependent manner. Each miRNA is predicted to target hundreds of genes, and a majority of protein-coding genes are computationally predicted to be miRNA targets. To test miRNA functions experimentally, we introduced the miRNA "sponge" method, which uses miRNA target mimics to sequester mature miRNAs and thereby create continuous miRNA loss of function in cell lines and transgenic organisms. Sponge RNAs contain complementary binding sites to a miRNA of interest, and are produced from transgenes within cells. As with most miRNA target genes, a sponge's binding sites are specific to the miRNA seed region, which allows them to block a whole family of related miRNAs. This transgenic approach has proven to be a powerful tool to generate miRNA phenotypes in a variety of experimental systems. Bulk measurements on populations of cells have indicated that, although pervasive, repression due to miRNAs is on average quite modest. To assay repression in single cells, we performed quantitative fluorescence microscopy and flow cytometry to monitor a target gene's protein expression in the presence and absence of regulation by miRNA. We found that repression among individual cells varies dramatically. miRNAs establish a threshold level of target mRNA below which protein production is highly repressed and above which expression responds ultra sensitively to target mRNA input until reaching high enough mRNA levels to almost escape repression. We constructed a mathematical model describing molecular titration of target mRNAs by miRNAs. The model predicted, and experiments confirmed, that the ultrasensitive regime could be shifted to higher target mRNA levels by increasing the miRNA concentration or the number of miRNA binding sites in the 3' untranslated region (UTR) of the target mRNA. Thus even a single species of miRNA can act both as a switch to effectively silence gene expression and as a fine-tuner of gene expression. This fits the emerging paradigm in which miRNAs help to confer robustness to biological processes by reinforcing transcriptional programs, attenuating leaky transcripts, and perhaps buffering random fluctuations in transcript copy number.
by Margaret S. Ebert.
Ph.D.
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Relli-Dempsey, Vincent M. T. Relli-Dempsey. "A Thermometric Titration Study of Acetaminophen and Sodium Hypochlorite." Ohio Dominican University Honors Theses / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=oduhonors152621864170557.
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Sasaki, Milton Katsumi. "Comparação entre analisadores com fluxo constante ou pulsado: aplicação a amostras de relevância farmacêutica, agronômica e/ou ambiental." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-26012016-152115/.
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Sistemas de análises químicas em fluxo com multi-impulsão empregam bombas solenoide como unidade propulsora de fluidos, as quais proporcionam fluxos pulsados. Estes provêm um eficiente transporte radial de massas, o que garante boa homogeneização das soluções envolvidas, mesmo em situações de dispersão limitada. O objetivo principal deste trabalho foi então comparar o desempenho de metodologias envolvendo reagentes imobilizados em sistemas de análises em fluxo com fluxos constantes ou pulsados. Para isto, foram selecionadas as determinações espectrofotométricas de ácido ascórbico em produtos farmacêuticos, utilizando reator tubular de polietileno (50 cm) com MnO2(s) imobilizado, e reação com formaldoxima (0,25 mol L-1); e de carbaril em águas naturais, explorando extração líquido-líquido com xileno imobilizado em membrana de PVDF, e solução de NaOH a 0,1 mol L-1 como fluxo aceptor. Adicionalmente, compararam-se os dois tipos de fluxo em uma nova titulação em fluxo, a titulação monitorada por traçador; a determinação de acidez total em vinagres foi selecionada e utilizaram-se as titulações por injeção em fluxo e programada em triângulo, ambas empregando solução de NaOH a 0,01 mol L-1 como titulante e fenolftaleína como indicador ácido-base, com monitoramento por traçador empregando azul brilhante FCF (ca. 6 mg L-1). Na determinação de ácido ascórbico, o desempenho do sistema com fluxos pulsados foi superior àquele com fluxos constantes quanto ao limite de detecção: 0,33 contra 0,60 mg L-1 (critério 3,3 ?), e à repetibilidade: d.p.r. estimado como 2,5 contra 5,6% (n = 20); quanto à exatidão, não foi encontrada diferença estatisticamente significativa entre o método proposto e o da Farmacopeia Britânica ao nível de confiança de 95%. Na determinação de carbaril, o uso de fluxos pulsados favoreceu a extração do analito, obtendo-se uma sensibilidade 9,3% maior relativamente ao emprego de fluxos constantes, além de uma melhor linearidade da curva analítica; entretanto, o método mostrou-se susceptível a interferência de outros metilcarbamatos, o que comprometeu sua aplicação à análise de águas naturais. Na determinação de acidez total, a exploração de fluxos pulsados proporcionou menores variações da razão dos valores de absorbância relativos ao monitoramento do traçador e do indicador; não foi encontrada diferença estatística entre as titulações em fluxo propostas e o método titulométrico de referência ao nível de confiança de 95%Multi-pumping flow systems use solenoid pumps as fluid propelling devices, which deliver pulsed flows. These flows provide an efficient radial mass transport, thus good mixing conditions even in limited sample dispersion situations. The main objective of this work was then to compare the performance of methodologies involving immobilized reagents in flow systems with constant or pulsed flows. To this end, the spectrophotometric determinations of ascorbic acid in pharmaceutical products using a 50-cm polyethylene tubular reactor with immobilized MnO2(s) with further colour-forming reaction with 0.25 mol L-1 formaldoxime; and carbaryl in natural waters exploiting liquid-liquid extraction with xylene immobilized in a PVDF membrane and a 0.1 mol L-1 ¬¬NaOH solution as acceptor stream, were selected. Moreover, constant and pulsed flows were compared in relation to a novel strategy for flow titration, named tracer-monitored titration; the determination of total acidity in vinegars was selected and flow injection and triangle-programmed titrations were applied, both using a 0.01 mol L-1 NaOH solution as titrant, phenolphtalein as acid-base indicator and ca. 6 mg L-1 brilliant blue FCF as tracer. Regarding ascorbic acid determination, the pulsed flow system was superior in relation to the constant flow system for detection limit: 0.33 against 0.60 mg L-1 (3.3 ? criterion), and for repeatability: r.s.d. estimated as 2.5 against 5.6% (n = 20); in relation to accuracy, no significant differences between the proposed method and that of the British Pharmacopoeia were found at the 95% confidence level. Regarding carbaryl determination, use of pulsed flows favored the analyte extraction, leading to a 9.3% sensitivity improvement in relation to use of constant flows; besides the attainment of better linearity of the analytical curve. The method was however susceptible to interference of other methylcarbamates, thus the application to natural water analyses was impaired. Regarding total acidity determination, pulsed flows exploitation provided lower variations in the ratio of absorbance values related to the monitoring of tracer and indicator; no significant differences between the proposed titrations and the reference method were found at the 95% confidence level
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Rabenstein, Björn. "Monte Carlo methods for simulation of protein folding and titration." [S.l. : s.n.], 2000. http://www.diss.fu-berlin.de/2000/124/index.html.
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Grünke, Silke. "Reaktionsmechanismen in der Karl-Fischer-Lösung." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=957132433.
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Ritchie, Jason Duane. "The distribution of charge and acidic functional groups in natural organic matter the dependence on molecular weight and pH /." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-08252005-125918/.
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Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2006.Michael Bergin, Committee Member ; E. Michael Perdue, Committee Chair ; Ching-Hua Huang, Committee Member ; Ellery Ingall, Committee Member ; Martial Taillefert, Committee Member. Vita. Includes bibliographical references.
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Pan, Haobo. "Solubility of calcium phosphates and related oral minerals by solid titration." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557558.
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Pan, Haobo, and 潘浩波. "Solubility of calcium phosphates and related oral minerals by solid titration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557558.
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Islam, Khan Md Shaiful. "Dose titration, tolerance and compatibility of some feed additives in broiler." [S.l. : s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB12046170.
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Richter, William Thompson. "Parameters of nicotine titration in addicted and non-addicted cigarette smokers." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91144.
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Nicotine titration was studied in cigarette smokers not interested in cutting down or quitting smoking. Forty smokers were classified as high nicotine dependent (n=20) and low nicotine dependent (n=20) using a validated tolerance questionnaire. Subjects were randomized into baseline (n=10) or nicotine fade conditions (n=10) within their dependency group. Subjects in the baseline conditions smoked their preferred brand of cigarette throughout the experiment. Smokers in the fade conditions switched to a reduced nicotine brand in the latter half of the procedure.
Multiple in vivo and in vitro measures of smoking rate and topography were collected over a four day period. Based on analyses of these data, it was concluded that no compensatory changes in smoking behavior occurred that were clearly attributable to nicotine titration. It was found that smokers classified as high nicotine dependent smoked more intensively that low dependent smokers.
The implications of these findings given the design and experimental controls employed in this experiment are discussed, and directions for future research explored.M.S.
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Baidya, Christina Autoshi. "Using molecular dynamics simulations to study titration behavior of fatty acids." Thesis, Uppsala universitet, Institutionen för farmaci, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-432854.
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Medium chain fatty acids (MCFAs) are essential molecules for a wide range of pharmaceutical, biotechnological, and industrial applications. These are naturally occurring saturated or unsaturated fatty acids containing 6-12 carbons with complex and pH sensitive aggregation. Medium chain fatty acids such as capric acid (C10) or lauric acid (C12) have additionally been shown to exhibit antibacterial activity. A number of studies have observed the aggregation behavior of long chain fatty acid using the titration curves by molecular dynamic (MD) simulations. In this study, we performed constant-pH coarse-grained MD simulations to determine pKa values and titration behavior using a two-states model for C10 and C12. In the simulations, pH was varied between 2 to 8 and pKa values were determined using the Hill equation. The pKa for C10 (capric acid) was found to be 4.8 and for C12 (lauric acid) 5.4, in good agreement with the literature values (4.9 and 5.3, respectively).
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Felix, Olivia. "Etude thermodynamique de la sorption de l'uranyle sur la monazite et la magnétite." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00737326.
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Les phénomènes d'adsorption interviennent dans les processus géochimiques gouvernant ainsi le transport des contaminants. Par ailleurs, les variations de température sont susceptibles d'influencer significativement leur comportement vis-à-vis de la surface des minéraux. Aussi, l'influence de la température sur la sorption doit être étudiée afin de mieux appréhender le devenir des éléments dans l'environnement. Dans cette optique, l'interaction entre un ion modèle, l'uranyle et deux minéraux a été étudiée. Dans un premier temps, un composé méthodologique, la monazite, a été choisi afin de déterminer la démarche à suivre pour étudier l'influence de la température sur la sorption de l'uranyle dans trois milieux plus ou moins complexants. Puis, des tests préliminaires ont été réalisés pour étudier la sorption de l'uranyle sur un composé d'intérêt industriel, la magnétite, en appliquant la démarche mise en place. Le solide a d'abord été caractérisé d'un point de vue massif puis les caractéristiques acido-basiques de sa mise en suspension dans les trois électrolytes (NaClO4, NaNO3 et Na2SO4) ont été étudiées en fonction de la température. Les constantes d'équilibre associées aux réactions de déprotonation des sites de surface ont été déterminées entre 25°C et 95°C par modélisation de courbes de titrages potentiométriques. Les simulations ont été effectuées en limitant au maximum le nombre de degrés de liberté du système. Le modèle 1-pK a donc été préféré au modèle 2-pK en raison du nombre de paramètres ajustables plus limité dans ce modèle. Des contraintes expérimentales telles que le pH de point de charge nulle ou les enthalpies déterminées par mesure directe des chaleurs associées par microcalorimétrie de mélange ont été imposées pour déterminer les constantes d'équilibre acido-basiques. La sorption de l'uranyle en fonction du pH sur le même intervalle de température a été étudiée en alliant l'acquisition de données macroscopiques telles que les sauts de sorption et la spéciation en solution à une étude structurale menée par analyse par spectrofluorimétrie laser permettant l'identification des espèces sorbées. La simulation des sauts de sorption permettant d'accéder aux constantes associées aux réactions de sorption a été réalisée en imposant les caractéristiques acido-basiques préalablement déterminées. Des mesures directes, par microcalorimétrie de mélange, des chaleurs mises en jeu lors de la sorption de l'uranyle ont permis de tester la validité de la loi de Van't Hoff sur ce phénomène. La même démarche a été suivie pour étudier l'influence de la température sur la sorption de l'uranyle sur la magnétite en milieu NaClO4 et NaNO3. Cependant, l'étude structurale par spectrofluorimétrie laser n'a pu être réalisée en raison de la couloration noire de la magnétite.
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Shih, Margaret. "Titrating and Evaluating Multiple Drug Regimens within Subjects." VCU Scholars Compass, 2001. http://scholarscompass.vcu.edu/etd/3897.
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The dosing of combination therapies is commonly undertaken empirically by practicing physicians, and there is a lack of a coherent algorithm to approach the problem of combination dosing. Current methods of evaluating multiple drug combinations in clinical trials generally do not provide information regarding the location of more effective dosages when the combination is not found to differ from the standard, even though the absence of a difference does not necessarily mean the new combination is ineffective. Additionally, if a new combination is found to be more effective, often a large proportion of the subjects has not benefited from the trial. This may lead to problems with patient enrollment and adherence to the study protocol, and even with early stopping rules, the time patients spend on inferior treatments may have lasting detrimental effects. This paper describes an evolutionary operation (EVOP) direct-search procedure to titrate combination doses within individual patients. The Nelder-Mead simplex direct-search method is used to titrate a combination of drugs within individual subjects. Desirability functions are incorporated to define the main response of interest and additional responses or constraints. Statistical methodology for determining whether the titrated treatment combination has resulted in an improvement in patient response and for evaluating whether a therapeutic synergism exists is developed. Inferences can be made about the efficacy of the combination or about the individual drugs that comprise the combination. This approach allows every patient the potential to benefit from the combination under study and permits the consideration of multiple endpoints simultaneously.
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Marklund, Erik. "Gas-Phase Protein Structure Under the Computational Microscope : Hydration, Titration, and Temperature." Doctoral thesis, Uppsala universitet, Beräknings- och systembiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-151006.
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Although the native environment of the vast majority of proteins is a complex aqueous solution, like the interior of a cell, many analysis methods for assessing chemical and physical properties of biomolecules require the sample to be aerosolized; that is, transferred to the gas-phase. An important example is electrospray-ionization mass spectrometry, which can provide a wide range of information about e.g. biomolecules. That includes structural features, charged sites, and gas-phase equilibrium constants of reactions. To date much of the microscopic detail about the aerosolization process remains beyond the limits of experimental observation. How is the gas-phase structure of a protein related to the solution-phase structure? How transferable are observations done in the gas phase to solution? On the basis of classical molecular-dynamics simulations this thesis reveals important features of gas-phase biomolecular structure near the end of the the aerosolization process, the relation between gas-phase structure and native structure, microscopic detail about the de-wetting of gas-phase biomolecules, and the impact of temperature and residual solvent on structure preservation. Residual solvent on proteins is shown to have a stabilizing effect on proteins, in part because it allows the scarcely hydrated protein to cool through solvent evaporation, but also because part of the solvent provides structural support by hydrogen bonding to the protein. The gas-phase structure of micellar aggregates is seen to depend on composition, where some types of lipids cause rapid micelle inversion, whereas others maintain much of their collective structure when transferred to the gas phase. The thesis also addresses proton-transfer reactions, which have an impact on the biophysical aspects of proteins, both in the gas phase and in solution. The thesis presents a computationally efficient method for including proton-transfer reactions in classical molecular-dynamics simulations, which expands the range of scientific problems that can be addressed with molecular dynamics.
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Chiad, Khalid [Verfasser]. "Adsorption of macromolecules on interfaces studied by isothermal titration calorimetry / Khalid Chiad." Mainz : Universitätsbibliothek Mainz, 2012. http://d-nb.info/1020163291/34.
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Horvath, Elisabet. "Appropriate conditions for polyelectrolyte titration to determine the charge of cellulosic fibers." Licentiate thesis, KTH, Fibre and Polymer Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1706.
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The polyelectrolyte titration method has been developed overthe years in order to determine the surface charge ofcellulosic fibers. The conditions have been varied depending onthe author. This work has been aimed at resolving theappropriate conditions for measuring the charge, such aselectrolyte concentration and molecular mass of thepolyelectrolyte. The charge ratio of variously treated pulpswas also investigated.
The polyelectrolyte titration technique is based on a 1:1adsorption stoichiometry between fiber and polyelectrolytecharges. Adsorption of polydiallyldimethylammonium chloride(poly-DADMAC) was first performed at various electrolyteconcentrations and then with various molecular masses. ESCA(Electron Spectroscopy for Chemical Analysis) was used toindependently validate the polyelectrolyte titrationmethod.
Results showed that stoichiometry prevailsat lowelectrolyte concentrations. Increasing the electrolyteconcentration screens the fiber charges, initially enhancingthe adsorption and causing a deviation from stoichiometry.Further increases in electrolyte concentration eventuallydecrease the adsorption. Deviation from stoichiometry occurredat higher electrolyte concentrations for higher charge densitypulps. ESCA-measurements showed that high and low molecularmass cationic polyelectrolyte adsorb to the same extent on thefiber surface, confirming stoichiometry. There was a goodagreement between the two techniques, hence, thepolyelectrolyte titration technique is a good method to measuresurface charges. Comparing the charge ratio between differentkind of pulps and treatments, it was found that mechanicalpulps have a higher surface charge than chemical pulps. Thecharge ratio of chemical pulps was, however, practicallyunchanged when comparing different types of wood and bleachingsequences.
KEYWORDS:Adsorption, electrolyte, polyelectrolyte,polyelectrolyte titration, charge stoichiometry, charge ratio,diffuse electric double layer, Debye length, poly-DADMAC,cellulosic fibers, ESCA.
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Ohyama, Tsuyoshi. "Thermodynamic studies of ligand binding to biological macromolecules by isothermal titration calorimetry /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu148794844082652.
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Hussain, Talib. "The application of microwave formulation and isothermal titration calorimetry for pharmaceutical compounds." Thesis, University of Huddersfield, 2014. http://eprints.hud.ac.uk/id/eprint/23397/.
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Solid dispersions are commonly used to overcome bioavailability issues of poorly water soluble drugs. Various preparation methods along with carrier systems have been used to develop solid dispersions. However, this study investigates the application of microwave heating methods in formulation development alongside associated analytical investigations. Formulations of poorly soluble drugs, namely, fenofibrate, gemfibrozil, ibuprofen, ibuprofen (+) S and phenylbutazone were prepared using a microwave technique and compared with standard formulation techniques. Mesoporous silicas and polyethylene glycol were used as excipients. Then in vitro dissolution analysis was carried out for the performance evaluation of the resultant formulations. It was found that effective products were produced as a result of microwave processing compared with the traditional techniques. Analytical techniques such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were employed to determine the solid state properties, i.e. thermal stability, crystalline state, physical appearance and chemical stability of developed formulations. The overall findings indicate that successful formulation can be achieved using microwave heating. Isothermal titration calorimetry (ITC) was used to probe the interactions of model drugs, namely, caffeine, diprophylline, etofylline, paracetamol and theophylline with excipients such as sodium dodecyl sulphate (SDS), sodium deoxycholate (NaDC) and PEG. Thermodynamic data suggests the successful use of ITC to investigate drug-excipient interactions. In summary, the potential of microwave heating in formulation development and ITC to characterise drug-excipient interactions was thoroughly investigated and both found as potential alternatives to more traditional techniques.
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Alex, Asha Philips. "Determination of silver(I) in the presence of silver(0) using EDTA titration." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21150.pdf.
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Amadi, Ovid Charles. "An isoperibol calorimeter for the investigation of biochemical kinetics and isothermal titration calorimetry." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40401.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 52).
Isothermal titration calorimetry is a technique used to measure the enthalpy change associated with a molecular binding interaction. From these data, the binding constant for the reaction can be determined. In the scope of a larger project to design a high sensitivity instrument for collecting such data, the current methods in isothermal titration calorimetry were investigated. Further calorimetric experience was acquired by designing a large scale calorimetric device. Dilution reactions with dimethyl sulfoxide and water were conducted to measure the excess enthalpy of binding. The inaccuracy of these measurements necessitated the more careful design of an isoperibol calorimeter. This calorimeter was modeled was an arrangement of coupled thermal masses and capacitances in order to fully understand its transient response to a thermal input. Dilution reactions and a neutralization reaction with HCl and NH40H were performed on the system and the results were used to make recommendations for the design of the future high sensitivity device.
by Ovid Charles Amadi.
S.B.
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Långström, Mikael. "Determination of zinc in samples from mining sites using complexometric titration with EDTA." Thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-119233.
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Walker, Karen Nicola. "Protein engineering and characterisation of an IgG-binding domain based upon protein G from Streptococcus group G." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296376.
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Kos, Nadja [Verfasser]. "Auswertungsmöglichkeiten und Optimierung potentiometrisch und photometrisch indizierter Titrationen / Nadja Kos." Berlin : Freie Universität Berlin, 2010. http://d-nb.info/1024743829/34.
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Sothirajah, Shobana. "Clinical Algorithms for Maintaining Asthma Control." University of Sydney, 2008. http://hdl.handle.net/2123/3546.
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Master of Science in MedicineRationale: Asthma management aims to achieve optimal control on the minimal effective dose of medication. We assessed the effectiveness of two algorithms to guide ICS dose in well-controlled patients on ICS+LABA in a double-blind study, comparing dose adjustment guided by exhaled nitric oxide (eNO) to clinical care algorithm(CCA) based on symptoms and lung function. Methods: We randomised non-smoking adult asthmatics on minimum FP dose 100μgs daily +LABA to ICS adjustment using eNO or CCA, assessed over 5 visits during 8 months treatment. Primary endpoints were asthma-free days and asthma related quality of life (QOL). Analysis was by mixed model regression and generalised estimating equations with log link. Results: 69 subjects were randomised (eNO:34, CCA:35) and 58 completed the study. At baseline mean FEV1 was 94% pred., mean eNO (200ml/sec) 7.1 ppb, median ACQ6 score 0.33. Median ICS dose was 500 μg (IQR 100-500) at baseline and 100 μg on both eNO (IQR 100-200) and CCA arms (IQR 100–100) at end of study. There were no significant differences between eNO and CCA groups in asthma-free days (RR=0.92, 95% CI 0.8–1.01), AQL (RRAQL
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CHen, Canghai. "Optimised dose titration for Duodopatreatment based on simulation experiments– implementation in a decision supportsystem." Thesis, Högskolan Dalarna, Datateknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-3978.
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The aim of this work was to design a set of rules for levodopa infusion dose adjustment in Parkinson’s disease based on a simulation experiments. Using this simulator, optimal infusions dose in different conditions were calculated. There are seven conditions (-3 to +3)appearing in a rating scale for Parkinson’s disease patients. By finding mean of the differences between conditions and optimal dose, two sets of rules were designed. The set of rules was optimized by several testing. Usefulness for optimizing the titration procedure of new infusion patients based on rule-based reasoning was investigated. Results show that both of the number of the steps and the errors for finding optimal dose was shorten by new rules. At last, the dose predicted with new rules well on each single occasion of majority of patients in simulation experiments.
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Macuráková, Viktória. "Interakce půdní organické hmoty s polutanty studovaná mikrokalorimetrickými technikami." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-433051.
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This diploma thesis dealt with the study of interactions of soil organic matter, specifically humic acids with a pollutant, where the surfactant Septonex was used. Humic acids were isolated from two different soils in the work, namely black earth and cambium. The theoretical part describes the formation of humic acids as such, their possible interactions with substances and the characterization of surfactants. The experimental part is devoted to the characteristics of humic acids using elemental analysis, thermogravimetry and then the most important part of the thesis, namely the monitoring of interactions using isothermal titration calorimetry. The experiment showed that the sample of isolated black earth at the surfactant concentration of 0,075 moldm3 had the best interaction with the surfactant.
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Mahsoub, Hassan Mostafa Mohammed. "Real Time PCR-Based Infectivity Assay and Characterization of Cell Surface Receptors for Turkey Hemorrhagic Enteritis Virus." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78332.
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Turkey hemorrhagic enteritis virus (THEV) is responsible for the hemorrhagic enteritis (HE) disease in commercial turkeys through infections by its virulent strains. HE is an acute condition characterized by depression, immunosuppression, bloody droppings, intestinal hemorrhage, and death. THEV (also known as turkey adenovirus 3) is an official member of the family Adenoviridae, genus Siadenovirus, species Turkey siadenovirus A.
Two main types of live vaccines are currently used for the protection of turkeys against HE; a crude splenic vaccine propagated in live turkeys, and a cell culture-based vaccine generated in RP19 cells. The only laboratory-adapted tests for assessing the titers of these vaccines are agar gel immunodiffusion test and cell culture endpoint dilution, respectively. The assays suffer from low sensitivity, inaccuracy, and time consumption.
A SYBR Green-based real time PCR assay for determining the genomic titer of THEV through the quantification of its hexon gene was developed. The assay was applied as a quality control for the titration of splenic vaccines and was found useful in distinguishing the differences in virus titer among many vaccine batches. Additionally, using the qPCR assay along with a cell culture system, a novel infectivity assay was developed for the titration of THEV, as an alternative for the endpoint dilution assay. Applying the assay on nine batches of commercial HE cell culture vaccines, high variations in infectious virus titers were detected. The new method is rapid, sensitive, and very accurate. A strong correlation was found between the genomic titer and qPCR infectious titer in HE cell culture vaccines. Moreover, the qPCR infectivity assay proved as an instrumental research tool. It was used to measure the effect of several treatments of RP19 cells on virus infection.
The main target cell type for THEV infection and replication is B-lymphocytes, which are represented in vitro by the B lymphoblastoid, RP19 cells. The cellular surface components used by the virus to gain entry into cells are unknown. As an adenovirus, we hypothesized that THEV uses two different molecules on RP19 cells for the attachment and internalization. A recent study has shown that the synthesized THEV fiber knob domain binds to sialyllactose, based on a glycan array analysis. In our studies, the treatment of RP19 cells with neuraminidases and lectins resulted in high reduction of virus entry, which provide a strong evidence of the utilization of cell surface sialic acids as attachment receptor for THEV. Destruction of surface carbohydrates and proteins on RP19 cells also reduced virus entry, indicating that these components are part of the THEV receptor. Using virus overlay protein blot assay, THEV was found to specifically bind to two RP19 surface membrane proteins, most likely, representing primary and secondary receptors for virus entry. Further studies are required to identify these proteins and verify their role in THEV endocytosis in host cells.Ph. D.
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Börjesson, Ulf Börjesson Ulf Erik. "Electrostatic interactions in computer simulations of biomolecular systems : influence of system size, solvation, and titration /." [S.l.] : [s.n.], 2004. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15454.
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Budukh, Parag P. "Application of isothermal titration calorimetry to the determination of functional stability of proteins in solution /." Full text available from ProQuest UM Digital Dissertations, 2006. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1410676511&SrchMode=1&sid=4&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1218548208&clientId=22256.
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Lounis, Feriel Meriem. "Etude des interactions entre polyélectrolytes de charges opposées par électrophorèse capillaire et titration calorimétrique isotherme." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT187/document.
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L’objectif de cette thèse est d’étudier les interactions entre polyélectrolytes (PE) de charges opposées par analyse frontale continue en électrophorèse capillaire (FACCE) et par titration calorimétrique isotherme (ITC), en fonction de la force ionique du milieu et des paramètres physico-chimiques relatifs aux deux partenaires (taux de charge chimique, masse molaire, ramification). Un copolymère statistique d’acrylamide et de 2-acrylamido-2-méthyl-propane sulfonate (PAMAMPS) de taux de charge variant entre 15% et 100% a été synthétisé et caractérisé pour cette étude. En tant que polycation modèle, la poly(L-lysine) a été retenue, sous sa forme linéaire (PLL) ou ramifiée / hyperbranchée (DGL). Des mesures par turbidimétrie ont permis d’étudier la stabilité des complexes de polyélectrolytes (PEC) en fonction de la force ionique du milieu. La détermination de la stœchiométrie des PEC par 1H-RMN a permis d’établir une règle générale pour prédire les stœchiométries de charge des PEC. Les paramètres thermodynamiques d’interactions (constantes et stœchiométries d’interaction, contribution entropique et enthalpique) ont été déterminés, par le tracé systématique des isothermes d’adsorption, en considérant le modèle d’interactions des sites indépendants de même énergie. Une dépendance linéaire entre le logarithme des constantes d’interactions et le logarithme de la force ionique a été observée. Cette dépendance en force ionique confirme le caractère entropique des interactions entre PE de charges opposées. Elle permet aussi de quantifier le nombre de contre-ions relargués lors de la formation du PEC. Cette quantité de contre-ions libérés a pu être comparée à la quantité totale de contre-ions condensés. Cette modélisation permet, en outre, de prédire les constantes d’interaction pour des taux de charge intermédiaires et à différentes forces ioniquesThe aim of this thesis is to study the interactions between oppositely charged polyelectrolytes (PE) by frontal analysis continuous capillary electrophoresis (FACCE) and isothermal titration calorimetry (ITC) as a function of the ionic strength of the medium and the physico-chemical properties related to the two partners (chemical charge density, molar mass, ramification). Statistical copolymers of acrylamide and 2-acrylamido-2-methyl-propane sulfonate (PAMAMPS) with chemical charge densities varying between 15% and 100% were synthesized and characterized for this study. Poly(L-lysine) under their linear (PLL) or ramified/hyperbranched (DGL) forms were used as model polycations. Turbidity measurements allowed the study of the stability of the polyelectrolyte complexes (PEC) as a function of the ionic strength of the medium. PEC charge stoichiometries were measured by 1H-NMR, and a general predictive rule that estimates the PEC charge stoichiometry was enounced. The thermodynamic binding parameters (binding constant, stoichiometry, enthalpic and entropic contributions) were determined, by systematically plotting the isotherms of adsorption, and using the model of independent and identical interacting sites. A linear dependence between the logarithm of the binding constants and the logarithm of the ionic strength was observed. This linear dependence confirmed the entropic character of the interactions between oppositely charged PE and allowed quantifying the number of released counter-ions that were compared to the total number of condensed counter-ions. Furthermore, this modelling allowed predicting the binding constants for intermediate chemical charge densities and at different ionic strengths
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Aubrun, Frédéric. "Bases pharmacologiques de la titration intraveineuse de morphine dans l'analgésie de la douleur aiguë postopératoire." Paris 6, 2005. http://www.theses.fr/2005PA066180.
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Duo, Tianmeng. "Fluoro-glycosyl acridinones as sensitive active site titrating agents for glycosidases." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/43910.
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Augner, Sven Thomas. "Neue Entwicklungen zur Durchführung automatisierter NMR-kontrollierter Titrationen von Phosphon- und Phosphinsäuren." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964783274.
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Charnier, Cyrille. "Fast characterization of the organic matter, instrumentation and modelling for the AD process performances prediction." Thesis, Montpellier, SupAgro, 2016. http://www.theses.fr/2016NSAM0016/document.
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La digestion anaérobie est un des piliers de l'économie circulaire européenne, produisant du méthane et des engrais organiques à partir de déchets. Le développement de ce secteur passe par la co-digestion et l’optimisation de l'alimentation des procédés. Cela nécessite l'estimation de l'état biologique du digesteur, la caractérisation du substrat ainsi que l’utilisation de modèles prédictifs simulant les performances du digesteur, pour lesquels les solutions actuelles ne sont pas adaptées. Dans cette thèse, un capteur titrimétrique couplant pH et conductivité électrique pour l'estimation des concentrations en acides gras volatils, carbone inorganique et azote ammoniacale a été conçu, améliorant la précision d'estimation des acides gras volatils de 14,5 par rapport aux capteurs actuels. Couplé à l’analyse du biogaz, il permet d'estimer l'état biologique du procédé. En parallèle, une analyse spectroscopique proche-infrarouge, estimant les teneurs en glucides, protéines, lipides, demande chimique en oxygène, rendement et cinétique de production de méthane a été développée réduisant le temps de caractérisation des substrats à quelques minutes. La caractérisation rapide des substrats est utilisée pour implémenter le modèle de digestion anaérobie ADM1 de l’IWA qui prédit les performances d'un digesteur dans des conditions de digestion optimales. Le couplage de l’estimation de l'état biologique à cette approche permet de corriger la prédiction en prenant en compte l'état actuel du digesteur. Cette approche fournit un outil prédictif puissant pour le contrôle avancé des unités de digestion anaérobie ainsi que l'optimisation de la recette d'alimentationAnaerobic digestion is an important pillar of the European circular economy, producing methane and organic fertilizers from waste. The development of the anaerobic digestion sector goes through co-digestion and feeding strategy optimization. Its development requires the biological state estimation of the plant, substrate characterization and predictive models simulating the plant performances, for which current solutions are not suitable. In this thesis, a titration sensor coupling pH and electrical conductivity for the estimation of volatile fatty acids, inorganic carbon and ammonia has been designed, improving the accuracy on volatile fatty acids estimation by 14.5 compared to current sensors. Along with biogas analyses, it allows estimating the biological state of the unit. Besides, fast near infrared spectroscopic analysis, estimating in a matter of minute carbohydrate, protein and lipid contents, chemical oxygen demand, methane production yield and kinetics, has been developed. Thus fast substrate characterization is then used to implement a modified Anaerobic Digestion Model n°1 which predicts the performances of a plant under optimal condition. Coupling biological state estimation to this approach enables to correct the prediction with the current state of the plant. This approach provides a powerful predictive tool for advanced control of anaerobic digestion plants and feeding strategy optimization
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Aw, Hong Wai. "Comparative binding studies with a tetraurea picket porphyrin receptor using 1H NMR and isothermal titration calorimetry." Thesis, Wichita State University, 2010. http://hdl.handle.net/10057/3664.
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The (α, α, α, α)-5,10,15,20-tetrakis(2-(4-fluorophenylurea)phenyl)porphyrin binds strongly (K(M-1)>104) to the chloride anion and close to 2-3 orders of magnitude less to the acetate anion, in DMSO-d6 as revealed by 1H NMR titration studies. However, the acetate anion showed stronger binding than the chloride anion when ITC analyses were done. Thus, the binding studies' results vary with the use of instrumental method. Other significant differences and similarities observed in the behavior of anion binding with the porphyrin receptor when using the two probes will also be addressed in this report.Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry
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Eimer, Sebastian [Verfasser]. "Titration mit oralem transmukosalem Fentanylcitrat und Morphinsulfat zur Dosisfindung einer Behandlung mit transdermalem Fentanylpflaster / Sebastian Eimer." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1020297565/34.
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Mwakibete, H. K. O. "Electrochemical and isothermal titration calorimetry studies associated with polymer-micelle complexes and surfactant/cyclodextrin inclusion complexes." Thesis, University of Salford, 1994. http://usir.salford.ac.uk/2145/.
Full textAbstract:
The effective degree of micellar dissociation of cetyltrimethylammonium bromide (CTAB) micelles has been determined from electrochemical (EMF) measurements using a CTAB selective electrode. Thermodynamic parameters have been determined using the `Ion binding model' and show dominance of hydrophobic interactions in free CTAB micellization. The enthalpy contribution is insignificant. The binding of the surfactant CTAB onto the neutral watersoluble hydrophobic polymers: poly(propylene oxide) (PPO), poly(vinylmethylether) (PVME) and ethyl(hydroxyethyl) cellulose (EHEC) has also been investigated by the EMF technique. In all cases it has been shown that the surfactant binds to the polymer and the bound surfactant exists in the form of small aggregates. The EMF data has been used to investigate the characterization of the binding process. The formation of inclusion complexes between alkylpyridinium bromide (CPyBr) and alkyltrimethylammonium bromide (CIITAB) with a- and ß-cyclodextrins (CDs) have also been investigated by the EMF technique. In addition the thermodynamics of the inclusion on a- and ß-CDs by the surfactants : CTAB, CPyBr, alkylsulfates (COSO3Na) , and alkanesulfonates (CnSO3Na) have been carried out using an Omega isothermal titration calorimeter (ITC). Whereas ß-CD systems form predominantly 1: 1 complexes, a-CD form 1: 1 and a 2: 1 complexes with surfactants having long hydrophobic tails. For both a- and ß-CD the complexation constants increase as the chain length of the surfactant increases, showing that the driving force dominating the formation of these complexes is the hydrophobic effect. The 1: 1 ß- CD/surfactant complexation is accompanied by large increase in entropy. The 1: 1 a-CD/surfactant complexation and all 2: 1 complexation are accompanied by a large increase in enthalpy.