Dissertations / Theses on the topic 'QSPkR'
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Gottipati, Gopichand. "PREDICTION OF HUMAN SYSTEMIC, BIOLOGICALLY RELEVANT PHARMACOKINETIC (PK) PROPERTIES USING QUANTITATIVE STRUCTURE PHARMACOKINETIC RELATIONSHIPS (QSPKR) AND INTERSPECIES PHARMACOKINETIC ALLOMETRIC SCALING (PK-AS) APPROACHES FOR FOUR DIFFERENT PHARMACOLOGICAL CLASSES OF COMPOUNDS." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3525.
Full textTurner, Joseph Vernon. "Application of Artificial Neural Networks in Pharmacokinetics." Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/488.
Full textTurner, Joseph Vernon. "Application of Artificial Neural Networks in Pharmacokinetics." University of Sydney, 2003. http://hdl.handle.net/2123/488.
Full textDavor, Lončar. "Definisanje lipofilnosti, farmakokinetičkih parametara i antikancerogenog potencijala novosintetisane serije stiril laktona." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=107622&source=NDLTD&language=en.
Full textThe behavior and the chromatographic lipophilicity natural styryl lactone 7-(+)-goniofufurone, 7-epi-(+)-goniofufurone, crassalactones B and C and twenty of their newlysynthesized derivatives and analogs were examined using reverse-phase high performance liquid chromatography in the two solvent systems. In previous studies it has been shown that these compounds have great biological potential toward several human tumor cell lines. Chromatographic behavior of the compounds is generally in accordance with their structure. The relationships between the chromatographic retention constants and the majority of their in silico lipophilicity parameters are linear. The application of chemometric QSRR analysis determined very good multiple linear regression predictive models of quantitative correlation between experimentally obtained chromatographic retention constant, which determines the retention of the compound in pure water and in silico molecular descriptors, i.e. the structure of the compound. The lipophilicity of the compounds has a major influence on their pharmacokinetics, i.e. ADME (absorption, distribution, metabolism, elimination) properties. The best multi-linear regression models depending on the pharmacokinetic parameters of styryl lactone and other molecular descriptors have been defined and statistically validated. In vitro cytotoxic activity of the compounds was evaluated according to four novel human malignant cell lines: prostate cancer (PC3), colon cancer (HT-29), melanoma (Hs294T), lung adenocarcinom (A549). The most active compound was tricyclic 4-fluorocinnamic analog, which exhibits a nanomolar activity (IC50 2,1 nM) toward melanoma cells. This compound is over 2250 times more active than commercial antitumor agent doxorubicin (DOX). SAR analysis has revealed a correlation between the structure and the biological activity of the compounds. Using the molecular docking the relationship of the styryl lactone and the target protein important for prostate cancer was examined. The compounds with high inhibitory activity against prostate cancer cells have a high docking score and are capable to form a coordinative-covalent bond with a Fe2+ ion present in the active centre of the enzyme. 3DQSAR analysis, which was performed by methods of comparative CoMFA and CoMSIA fields, has formed a good predictive model between chemical structure and biological activity of the styryl lactone.
Al, Tafif Abdullah. "PREDICTION OF HUMAN SYSTEMIC, BIOLOGICALLY RELEVANT PHARMACOKINETIC PROPERTIES BASED ON PHYSICOCHEMICAL PROPERTIES OF CALCIUM CHANNEL BLOCKERS." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2868.
Full textBadri, Prajakta. "PREDICTION OF HUMAN SYSTEMIC, BIOLOGICALLY RELEVANT PHARMACOKINETIC (PK) PROPERTIES BASED ON QUANTITATIVE STRUCTURE PHARMACOKINETIC RELATIONSHIPS (QSPKR) AND INTERSPECIES PHARMACOKINETIC ALLOMETRIC SCALING (PK-AS)." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/124.
Full textTämm, Kaido. "QSPR modeling of some properties of organic compounds /." Online version, 2006. http://dspace.utlib.ee/dspace/bitstream/10062/475/5/tammkaido.pdf.
Full textAl-Fahemi, Jabir Hamad. "Momentum-space descriptors for QSPR and QSAR studies." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439465.
Full textEspinosa, Porragas Gabriela. "Modelos QSPR/QSAR/QSTR basados en sistemas neuronales cognitivos." Doctoral thesis, Universitat Rovira i Virgili, 2002. http://hdl.handle.net/10803/8505.
Full textLas redes neuronales (ANN) constituyen una alternativa para el desarrollo de algoritmos predictivos aplicados en diversos campos como: análisis masivo de bases de datos, para subsanar los obstáculos derivados de la selección o la multicolinealidad de variables, así como la sensibilidad de los modelos a la presencia de ruido en los datos de entrada al sistema neuronal. En la mayoría de los casos, las redes neuronales han dado mejores resultados que los métodos de regresión multilineal (MLR), el análisis de componentes principales (PCA), o los métodos de mínimos cuadrados parciales (PLS) debido a la no linealidad inherente en los modelos de redes.
En los últimos años el interés por los modelos QSPR/QSAR basados en redes neuronales se ha incrementado. La principal ventaja de los modelos de redes recae en el hecho que un modelo QSAR/QSPR puede desarrollarse sin especificar a priori la forma analítica del modelo. Las redes neuronales son especialmente útiles para establecer las complejas relaciones existentes entre la salida del modelo (propiedades físico químicas o biológicas) y la entrada del modelo (descriptores moleculares). Además, permiten clasificar los compuestos de acuerdo a sus descriptores moleculares y usar esta información para seleccionar el conjunto de índices capaz de caracterizar mejor al conjunto de moléculas. Los modelos QSPR basados en redes usan principalmente algoritmos del tipo backpropagation. Backpropagation es un sistema basado en un aprendizaje por minimización del error. Sin embargo, ya que los compuestos químicos pueden clasificarse en grupos de acuerdo a su similitud molecular, es factible usar un clasificador cognitivo como fuzzy ARTMAP para crear una representación simultánea de la estructura y de la propiedad objetivo. Este tipo de sistema cognitivo usa un aprendizaje competitivo, en el cual hay una activa búsqueda de la categoría o la hipótesis cuyos prototipos provean una mejor representación de los datos de entrada (estructura química).
En el presente trabajo se propone y se estudia una metodología que integra dos sistemas cognitivos SOM y fuzzy ARTMAP para obtener modelos QSAR/QSPR. Los modelos estiman diferentes propiedades como las temperaturas de transición de fase (temperatura de ebullición, temperatura de fusión) y propiedades críticas (temperatura y presión), así como la actividad biológica de compuestos orgánicos diversos (indicadores de toxicidad). Dentro de este contexto, se comparan la selección de variables realizados por métodos tradicionales (PCA, o métodos combinatorios) con la realizada usando mapas auto-organizados (SOM).
El conjunto de descriptores moleculares más factible se obtiene escogiendo un representante de cada categoría de índices, en particular aquel índice con la correlación más alta con respecto a la propiedad objetivo. El proceso continúa añadiendo índices en orden decreciente de correlación. Este proceso concluye cuando una medida de disimilitud entre mapas para los diferentes conjuntos de descriptores alcanza un valor mínimo, lo cual indica que el añadir descriptores adicionales no provee información complementaria a la clasificación de los compuestos estudiados. El conjunto de descriptores seleccionados se usa como vector de entrada a la red fuzzy ARTMAP modificada para poder predecir.
Los modelos propuestos QSPR/QSAR para predecir propiedades tanto físico químicas como actividades biológicas predice mejor que los modelos obtenidos con métodos como backpropagation o métodos de contribución de grupos en los casos en los que se apliquen dichos métodos.
One of the most attractive applications of computer-aided techniques in molecular modeling stands on the possibility of assessing certain molecular properties before the molecule is synthesized. The field of Quantitative Structure Activity/Property Relationships (QSAR/QSPR) has demonstrated that the biological activity and the physical properties of a set of compounds can be mathematically related to some "simple" molecular structure parameters.
Artificial neural network (ANN) approaches provide an alternative to established predictive algorithms for analyzing massive chemical databases, potentially overcoming obstacles arising from variable selection, multicollinearity, specification of important parameters, and sensitivy to erroneous values. In most instances, ANN's have proven to be better than MLR, PCA or PLS because of their ability to handle non-linear associations.
In the last years there has been a growing interest in the application of neural networks to the development of QSAR/QSPR. The mayor advantage of ANN lies in the fact QSAR/QSPR can be developed without having to a priori specify an analytical form for the correlation model. The NN approach is especially suited for mapping complex non-linear relationships that exists between model output (physicochemical or biological properties) and input model (molecular descriptors). The NN approach could also be used to classify chemicals according to their chemical descriptors and used this information to select the most suitable indices capable of characterize the set of molecules. Existing neural networks based QSAR/QSPR for estimating properties of chemicals have relied primarily on backpropagation architecture. Backpropagation are an error based learning system in which adaptive weights are dynamically revised so as to minimize estimation errors of target values. However, since chemical compounds can be classified into various structural categories, it is also feasible to use cognitive classifiers such as fuzzy ARTMAP cognitive system, for unsupervised learning of categories, which represent structure and properties simultaneously. This class of neural networks uses a match-based learning, in that it actively searches for recognition categories or hypotheses whose prototype provides an acceptable match to input data.
The current study have been proposed a new QSAR/QSPR fuzzy ARTMAP neural network based models for predicting diverse physical properties such as phase transition temperatures (boiling and melting points) and critical properties (temperature and pressure) and the biological activities (toxicity indicators) of diverse set of compounds. In addition, traditional pre-screening methods to determine de minimum set of inputs parameters have been compared with novel methodology based in self organized maps algorithms.
The most suitable set of molecular descriptor was obtained by choosing a representative from each cluster, in particular the index that presented the highest correlation with the target variable, and additional indices afterwards in order of decreasing correlation. The selection process ended when a dissimilarity measure between the maps for the different sets of descriptors reached a minimum valued, indicating that the inclusion of more descriptors did not add supplementary information. The optimal subset of descriptors was finally used as input to a fuzzy ARTMAP architecture modified to effect predictive capabilities.
The proposed QSPR/QSAR model predicted physicochemical or biological activities significantly better than backpropagation neural networks or traditional approaches such as group contribution methods when they applied.
Aguado, Ullate Sonia. "Modeling of homogeneous catalysis: from dft to qspr approaches." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/79119.
Full textCatalysis is a field of science that explores solutions to environmental problems such as pollution, elimination of waste generated in the process of materials synthesis or regeneration of natural resources. In the present Thesis, we have reported a DFT study on the N-H σ-bond activation of ammonia by the µ3-alkylidyne titanium species using the [{Ti(η5-C5H5)(µ-O)}3(µ3-CH)] model complex. Afterwards, we have combined the TS-based approach and qualitative analysis through a newly defined molecular descriptor (distance-weighted volume, VW), in order to analyze the asymmetric hydroformylation of styrene catalyzed by Rh-binaphos complexes. Using our previous mechanistic knowledge, we have presented a QSPR study to predict the activity and the enantioselectivity in the hydroformylation of styrene catalyzed by Rh-diphosphane complexes. We have also developed a new methodology to predict enantioselectivity based on the quantitative quadrant-diagram representation of the catalysts and 3D-QSSR modeling; and we have applied it in the asymmetric cyclopropanation of alkenes catalyzed by copper complexes.
Fara, Dan Cornel. "QSPR modeling of complexation and distribution of organic compounds /." Online version, 2004. http://dspace.utlib.ee/dspace/bitstream/10062/475/5/tammkaido.pdf.
Full textVijay, Vikrant. "Assessment of Cutaneous Permeability of Biocides in Mixtures using QSPR Approach." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-06292009-233331/.
Full textOprisiu, Ioana. "Modélisation QSPR de mélanges binaires non-additifs : application au comportement azéotropique." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00862598.
Full textKucia, Urszula. "Analizy QSPR wielkich bibliotek związków chemicznych na przykładzie bazy danych Abamachem." Doctoral thesis, Katowice : Uniwersytet Śląski, 2019. http://hdl.handle.net/20.500.12128/12222.
Full textFayet, Guillaume. "Développement de modèles QSPR pour la prédiction des propriétés d'explosibilité des composés nitroaromatiques." Phd thesis, Paris 6, 2010. http://pastel.archives-ouvertes.fr/pastel-00006157.
Full textPeng, Xiaoling. "Methods of variable selection and their applications in quantitative structure-property relationship (QSPR)." HKBU Institutional Repository, 2005. http://repository.hkbu.edu.hk/etd_ra/594.
Full textJamshidian, Majid. "Inclusion et libération de molécules antioxydantes dans un emballage à base d’Acide Poly Lactique en contact alimentaire." Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL109N/document.
Full textActive packaging generates longer shelf-life foods, lower usage of additives and preservatives in food formulations, higher protection of flavors and higher food qualities. Antioxidant controlled release from packaging provides longer food stability (reduced lipid oxidation) by continuously liberating antioxidants at food surface. The overall objective of the present work was to study the suitability of Poly Lactic Acid (PLA, biodegradable polymer industrially produced) as active packaging. We chose various synthetic or natural antioxidants including alpha-tocopherol, Ascorbyl palmitate, BHA, BHT, Propyl gallate and TBHQ to produce the antioxidant packaging. Firstly, the mode of incorporation of these antioxidants in PLA matrix and also their potential effects on diverse structural, thermal, mechanical and barrier properties of PLA were investigated. The release study of antioxidants was accomplished from PLA-antioxidants films into three food simulants, i.e. 95%, 50%, and 10% ethanol at two temperatures (20°C and 40°C). The results showed that PLA has the capability for being as a suitable carrier for antioxidant-active packaging for some food products. Finally, a mathematical model based on quantitative structure property relationships (QSPR) was developed to predict antioxidant diffusion in food simulant/ active packaging system
Plass, Monika. "The influence of conformational and associative effects on the QSPR descriptors of oligopeptide derivatives." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=96170795X.
Full textKhabzina, Yoldes. "Influence des cations d'échange dans les zéolithes type faujasites sur la sélectivité d'adsorption des isomères du xylène." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10008.
Full textFor several years, IFPEN develops based faujasite adsorbents for the xylene separation process. In this context, this thesis allowed to streamline the selectivity origins of xylene isomers in faujasite zeolites. To do it, a new approach is proposed. The objective is to establish, at the same time, an explanatory and predictive model which allows to relate the selectivity to a number of characteristic parameters of the system, called descriptors. After the proposal of an experimental design containing about sixty adsorbents, their preparation and their test were made by using automated and paralleled adequate tools. A descriptive statistical analysis made on 43 evaluated adsorption properties revealed the existence of 4 various classes of adsorbents. The stage of the model construction was preceded by the identification and the calculation of descriptors. Those who are retained characterize, essentially, the confinement state responsible for the selectivity within the zeolite. We quote the sites II cations size, the sites III occupation or still the sites II saturation. Two statistical methods were used to build the structures-properties relationship. First, a multiple linear regression with, as predictive variables, the 3 quoted descriptors. The retained explanatory model predicts with a correlation coefficient R² = 0,78. So, the discriminant analysis was used. The same 3 descriptors served to predict the affectation of adsorbents in the 4 identified classes with a total prediction percentage of 76 %
Moda, Tiago Luiz. "Desenvolvimento de modelos in silico de propriedades de ADME para a triagem de novos candidatos a fármacos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-22032007-112055/.
Full textMolecular modeling tools and quantitative structure-activity relantionships (QSAR) or structure-property (QSPR) are integrated into the drug design process in the search for new bioactive molecules with good pharmacokinetic and pharmacodynamic properties. The Medicinal Chemistry work carried out in this Masters dissertation concerned studies of the quantitative relationshisps between chemical structure and the pharmacokinetic properties oral bioavailability and plasma protein binding. In the present work, standard data sets for bioavailability and plasma protein binding were organized encompassing the structural information and corresponding pharmacokinetic data. The created data sets established the scientific basis for the development of predictive models using the hologram QSAR and VolSurf methods. The final HQSAR and VolSurf models posses high internal and external consistency with good correlative and predictive power. Due to the simplicity, robustness and effectivess, these models are useful guides in Medicinal Chemistry in the early stages of the drug discovery and development process.
Kireeva, Natalia. "Ensemble QSPR modeling of stabilities of metal : ligands complexes and melting points of ionic liquids." Strasbourg, 2009. http://www.theses.fr/2009STRA6008.
Full textPaula, Fávero Reisdorfer. "QSPR/SAR em derivados 5-nitro-heterocíclicos com atividades antichagásica. Estudo das relações entre o potencial de redução do grupo nitro e propriedades físico-químicas." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/9/9135/tde-29052007-152154/.
Full textSome nitrocompounds have show activity against to Trypanosoma cruzi. Those biological activity are resulting from nitro group reduction with subsequent formation of radical nitro anion and other reaction\'s intermediates, which are toxic to the parasite. The structural difference among the 5-nitro-heterocyclic derivatives might exert influence on these compounds reduction and also on the antichagasic activity. In this way, the study of reduction process by voltammetric techniques, such as cyclic voltammetry and square wave voltammetry, is a mode of evaluate the biological action mechanism. Therefore, the evaluation of the electrodic process and the determination of nitrocompounds reduction potential provide information for elucidating the antitrypanosomal activity mechanism. In the present work, the procedures employed to determinate the cathodic reduction and reduction potentials were carried out on twenty three nitrocompounds (5-nitro-2-tiofilidenic benzhidrazides and 5-nitro-2-furfurilidenic benzhidrazides) with the aim using those data in QSPR and SAR analysis. Cyclic voltammetry and square wave voltammetry techniques were used to determined the reduction potential in electrochemical cell of 10 mL in the protic media (PIPES buffer and electrolyte of support NaNO3 0.1 mol L-1), mixed media of DMSO and PIPES buffer 50:50 v/v (electrolyte of support NaNO3 0.1 mol L-1), and aprotic media of DMSO (electrolyte of support Bu4NH4BF4 0.1 mol L-1). The reference and counter electrodes used were Ag/AgCl (with KCl saturated) and platinum, respectively. In these studies, the work electrodes were glassy carbon (aprotic and mixed media), carbon paste (mixed and protic media) and carbon paste modified with nitrocompounds (protic media). Molecular modeling studies and UV/visible spectrophotometry were investigated with the aim for determining the lowest conformational energy and the occurrence of co-planarity molecular structure. In this work were performed the geometry optimization (using the quantum chemistry AM1, ab initio HF3-21G* and HF6-31G* level of theory), conformational analysis(AM1 and ab initio HF6-31G*) and single point calculations (AM1). All the lowest energy conformers from conformational analysis were submitted to single point calculations. These models were used to determine the physicochemical properties (energy of formation in vacuum and solvated media, energy of HOMO, energy of LUMO, dipole moment, hardness, chemistry potential, electronic affinity, ionization potential and charges of electrostatic potential) and the molecular electrostatic potential, HOMO and LUMO maps, respectively. All calculations were performed using the computational software Spartan O2 for Linux, Spartan O4 for Windows, and the ClogP 4.0 (only for hydrophobicity). The cathodic reduction and half-wave potentials values and the set of physicochemical properties, which are obtained from quantum chemistry calculations, as well as the electronic effect (σp and σR derived of σ Hammett) and the hydrophobicity property (ClogP, and π of Hansch) were used in QSPR analysis applying Hansch analysis and PLS methodologies. Afterwards, the antichagasic activity of ten compounds (eight thiofilidenic and two furfurylidenic derivatives) was evaluated considering the influence of nitrocompounds reduction on biological activity. This assay allows to analyse the antiproliferative effect of nitrocompounds on the parasites growing, in twenty-four (24) hours, reading the number of trypanosomes in Haemocytometer. The voltammetric methodologies allowed to determinate the cathodic reduction and half-wave potential values in aprotic and mixed media to all nitrocompounds. In protic media, however, the cathodic reduction potential values were obtained only for the 5-nitro-2-tiofilidenic benzhidrazides. Those procedures seen to be appropriated for perform the electrochemistry reduction evaluation. The geometry optimization and conformational analysis allows determining a lack of structural planarity in all derivatives located at the bond between the carbonilic carbon and benzhoyl group. Additionally, the electrostatic potential maps presented a decreased on the electronic conjugate effect of the structures of nitrocompounds investigated. The conformational analysis allows us to determine the nitroheterocyclic biosostere conformations dependence on the reaction phase studied. The UV/visible spectra presented two waves, which are indicating responses related to different chromophores. These results suggest the absence of conjugate effect in nitrocompound structure, indicating that the presence of groups attached to benzene ring do not exert influence on the nitro group attached to heterocyclic ring. In the QSPR analysis was not detected any correlations between thel physicochemical properties and the cathodic reduction and reduction potentials, in all reaction media investigated. Those results might be occurred due to the lack of molecular co-planarity, which is reducing the influence of any property on the nitrocompounds reduction. Almost all nitrocompounds investigated show higher antichagasic activity than the reference drug, benznidazol. In a preliminary analysis it was verified that the cathodic reduction and half-wave potentials do not exert influence on the nitrocompounds antichagasic activity.
Olguín, Carlos José Maria. "Modelagem do coeficiente de sorção do solo de poluentes orgânicos persistentes no meio ambiente." Universidade Estadual do Oeste do Paraná, 2017. http://tede.unioeste.br/handle/tede/3006.
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The soil sorption coefficient normalized for organic carbon content (Koc) is a physicochemical parameter used in environmental risk assessments to determine the final destination of chemicals released in the environment. So, in oreder to predict this parameter, several models were proposed based on the relationship between LogKoc and LogP. The difficulty and cost to obtain experimental values of LogP have drawn to the algorithms development to calculate those values. Thus, in the first paper of this thesis, several free algorithms were considered to calculate LogP, and it was concluded that the best QSPR models to predict soil sorption coefficient of organic nonionic compounds were obtained using ALOGPs, KOWWIN and XLOGP3 algorithms. This study demonstrated the importance and usefulness of the statistical equivalence test used, since it allowed us to state that the models obtained from the considered algorithms are statistically equivalent. In this study, the both importance and usefulness of the statistical equivalence test were proved. These data allowed us to state that the models that have been obtained from the algorithms are statistically equivalent. Thus, in the impossibility of obtaining LogP values based on one of the algorithms, values obtained by another one of them can be used. It was also observed that the models presented in this study presented statistical quality and predictive capacity compatible with more complex models recently published in the area. In addition, it is a well accepted practice in the area the requirement to validate the prediction of a QSPR model from a data set that was not used in the model generation. In this context, some studies have explored the impact that several sizes of training sets would have on the predictive capacity of the generated QSPR models, consequently not reaching conclusive results. Thus, the second paper has been shown that, from not so large training sets, statistically equivalent QSPR models can be developed and that these models have similar predictive capacity to those ones created from a larger training set. Therefore, models were generated considering LogP values of the total training set, calculated with the ALOGPs algorithm and also with subsets of itself (i.e., halves, quarters and eighths). This study, just like the previous one, has confirmed the importance of using the statistical equivalence test since it was ascertained that, following the adopted procedures, the models obtained with subsets of the training set are statistically equivalent
O coeficiente de sorção do solo normalizado para o conteúdo de carbono orgânico (Koc) é um parâmetro físico-químico utilizado em avaliações de risco ambiental e na determinação do destino final das substâncias químicas lançadas na natureza. Vários modelos para prever este parâmetro foram propostos com base na relação entre LogKoc e LogP. A dificuldade e o custo para a obtenção de valores experimentais de LogP levaram ao desenvolvimento de algoritmos para calculá-los. Assim, no primeiro artigo desta tese foram considerados diversos algoritmos gratuitos para cálculo de LogP, e concluiu-se que os melhores modelos QSPR para predizer o coeficiente de sorção do solo de compostos orgânicos não iónicos foram obtidos usando os algoritmos ALOGPs, KOWWIN e XLOGP3. Neste estudo, foram demonstradas a importância e a utilidade do teste de equivalência estatística utilizado, dados que nos permitiram afirmar que os modelos obtidos dos algoritmos considerados são estatisticamente equivalentes. Assim, na impossibilidade de obterem-se valores de LogP a partir de um dos algoritmos, valores obtidos por outro podem ser usados. Verificou-se ainda que os modelos apresentados neste estudo possuem qualidade estatística e capacidade de predição compatíveis à de modelos mais complexos, publicados recentemente na área. Adicionalmente, a necessidade de se realizar a validação da predição de um modelo QSPR a partir de um conjunto de dados que não foi utilizado na geração do modelo é uma prática bem aceita na área. Nesse contexto, alguns trabalhos exploraram o impacto que diversos tamanhos de conjuntos de treinamento teriam na capacidade de predição dos modelos QSPR gerados, não chegando a resultados conclusivos. Assim, no segundo artigo desta tese, foi mostrado que, a partir de conjuntos de treinamento não tão grandes, modelos QSPR estatisticamente equivalentes podem ser desenvolvidos e que tais modelos têm capacidade de predição similar daqueles criados a partir de um conjunto de treinamento maior. Para isto, modelos foram gerados considerando valores de LogP do conjunto de treinamento total, calculados com o algoritmo ALOGPs e também com subconjuntos do mesmo (i.e., metades, quartos e oitavos). Este estudo, assim como o anterior, confirmou a importância do uso do teste de equivalência estatística utilizado nesta tese já que foi verificado que, seguindo os procedimentos adotados, os modelos obtidos com subconjuntos do conjunto de treinamento são estatisticamente equivalentes.
Jover, Modrego Jesús. "Aplicació de la metodologia QSPR al càlcul de propietats de compostos inorgànics i de sistemes multicomponents." Doctoral thesis, Universitat de Barcelona, 2008. http://hdl.handle.net/10803/665934.
Full textDelouis, Grace. "Modélisation QSPR de solvants d’intérêt technologique : les liquides ioniques et les électrolytes pour batteries Li-ion." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF035/document.
Full textThis thesis is dedicated to the modelling of ionic liquids and electrolytes of Li-ion batteries. We developed several SVR models in order to predict 9 interesting properties of these solvents. The models built for the ionic liquids allowed us to detect several problems, and are freely available on the laboratory’s website: infochim.u-strasbg.fr/webserv/VSEngine.html. The models built for the electrolytes were used to model some candidates tested experimentally by our colleagues. As the amount of data is quite small for these solvents, we also tested the transductive approach with the help of the TRR (Transductive Ridge Regression). We have developed an optimization procedure for the method’s parameters, and applied the TRR to the studied solvents. The results obtained with the TRR are slightly better than of the Ridge Regression but stay modest if we want to avoid any accidental damage of the model
Amboni, Renata Dias de Mello Castanho. "Estudo da correlação quantitativa entre estrutura e propriedade (QSPR) usando descritores topológicos para compostos carbonílicos alifáticos." Florianópolis, SC, 2001. http://repositorio.ufsc.br/xmlui/handle/123456789/81581.
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Neste trabalho foi aplicada a relação quantitativa entre estrutura e atividade, empregando-se diferentes descritores moleculares para estimar o odor frutal de ésteres alifáticos. Os parâmetros estatísticos, obtidos nas equações para os ésteres, empregando-se o método de regressão linear múltipla, foram de boa qualidade. O modelo obtido teve uma alta capacidade de predição, como estabelecido pelo coeficiente de validação cruzada. O método semi-empírico topológico (IET) foi ampliado para estimar a retenção cromatográfica, em fases estacionárias de baixa polaridade, de ésteres, aldeídos e cetonas lineares e ramificados. Os parâmetros estatísticos das regressões lineares simples entre os índices de retenção de Kováts e o IET foram excelentes para todos os compostos. Os modelos de correlação quantitativa entre estrutura e retenção cromatográfica obtidos com um único descritor tiveram alta capacidade de predição, além de apresentarem uma melhora na ordem de precisão e exatidão que os métodos de regressão linear múltipla. Este IET foi aplicado para estimar o ponto de ebulição de aldeídos e cetonas e os valores de "threshold" de odor de cetonas com odor canforáceo e frutal. Os pontos de ebulição de 35 aldeídos e cetonas foram precisamente estimados através de uma regressão linear simples e os valores dos "thresholds" de odor de 27 cetonas foram estimados através de uma função polinomial quadrática. Assim, o método semi-empírico topológico, baseado no comportamento geral da retenção cromatográfica de ésteres, aldeídos e cetonas utilizando um único descritor, representa um grande avanço nos estudos de correlação quantitativa entre estrutura e propriedade (QSPR).
Valenzuela, Venegas Guillermo Andrés. "Diseño y análisis de significancia estadística de descriptores en la elección de moléculas a reformar utilizando CAMPD." Tesis, Universidad de Chile, 2014. http://www.repositorio.uchile.cl/handle/2250/116855.
Full textHoy en día, para cubrir las necesidades energéticas a nivel industrial, de transporte y social, se utilizan combustibles fósiles, los que dañan el medio ambiente. Una alternativa para reemplazar esta fuente es el hidrógeno, el que puede ser producido a través del reformado de compuestos orgánicos como el metanol, metano, etanol, glicerol, pentano, hexadecano, entre otros. Pero, ya que se tiene un conjunto de compuestos reformables, cabe pensar lo siguiente ¿Son éstas las mejores moléculas para reformar? ¿Cuál es la mejor? ¿Cómo se podría determinar? Estas preguntas resultan difíciles de responder, ya que corresponden a un problema inverso y de optimización, cuya resolución es lenta y costosa. La solución que se propone, es utilizar CAMPD (Computer Aided Molecular and Process Design), que considera la definición de descriptores y QSPRs, para estimar el comportamiento de las propiedades macroscópicas (variables de salida que se desean optimizar) a partir de propiedades microscópicas (variables de entrada), para así facilitar el ciclo de optimización. CAMPD por su parte, está vinculado con el concepto de piezas, que se utilizan para generar los compuestos candidatos que cumplen las propiedades macroscópicas objetivo. Es por eso, que el presente trabajo, se enmarca en la primera etapa de CAMPD, lo que corresponde a definir descriptores estadísticamente significativos para el desempeño de moléculas en el proceso de reformado y proponer un tamaño de piezas que pueda representar al conjunto de moléculas a analizar y que genere la menor cantidad estructuras infactibles fisicoquímicamente. En cuanto al tamaño de piezas, se selecciona al grupos de átomos, ya que logran representar la totalidad del conjunto de compuestos y generar alrededor de 140 estructuras infactibles. Por otro lado, se determina que los descriptores que se obtienen para las propiedades macroscópicas: rendimiento de hidrógeno, emisiones y costo de producción; son el número de carbonos (Z1), hidrógenos (Z2) y grupos OH (Z3). Por su parte, a través del PCA, se obtienen dos variables, v1 = Z1 y v2 = 0.42Z2 + 0.903Z3 que resumen y explican el comportamiento de las tres propiedades macroscópicas. Cabe señalar, que podrían existir más descriptores (como el ángulo de enlace o la accesibilidad al carbono), pero no se opta por ellos, ya que su cálculo es muy complejo. Por último, se debe señalar que muchos de los datos que se utilizan en el análisis cuantitativo y cualitativo, son estimados, por lo que las relaciones obtenidas, podrían no ser tan acertadas. Además, el análisis cuantitativo, solo determina si existe alguna relación lineal entre las variables, por lo que puede generar sesgo en los resultados. Sin embargo, se debe destacar el desarrollo de una estrategia para abordar este problema (o alguno similar), una vez que se posean todos los datos necesarios y, así, obtener las relaciones correctas. No disponible a texto completo No autorizada por el autor a ser publicada a texto completo en Cybertesis.
Liu, Tao. "Chemoinformetics for green chemistry." Doctoral thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-8634.
Full textGlavatskikh, Marta. "Modeling and visualization of complex chemical data using local descriptors." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAF008/document.
Full textThis work describes original approaches for predictive chemoinformatics modeling of molecular interactions and reactions as a function of the structures of interacting partners and of the chemical environment (experimental conditions). Chemical structures have been encoded by local ISIDA MA-based or CGR-based descriptors, specifically targeting the active centers and their closest environment. The local descriptors have been combined with the specific parameters of experimental conditions, thereby encoding a particular chemical object. The methodology has been successfully applied for QSPR modeling of thermodynamic and kinetic parameters of intermolecular interactions (halogen and hydrogen bonds), tautomeric equilibria and chemical reactions (cycloaddition and SN1). GTM method has been applied for the first time for QSPR modeling and visualization of mixed chemical data. This method successfully separates data clusters on account of both chemical structures and experimental conditions
Al-Antary, Doaa Tawfiq, and Doaa Tawfiq Al-Antary. "The Estimation of Selected Physicochemical Properties of Organic Compounds." Diss., The University of Arizona, 2018. http://hdl.handle.net/10150/626758.
Full textSantos, Victor Hugo Jacks Mendes dos. "Uma perspectiva da modelagem QSPR para triagem/desenho de catalisadores para a s?ntese de carbonatos oleoqu?micos." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/8260.
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To date, only a small number of organocatalysts have been applied to produce oleochemical carbonates, while the description of new catalysts system still limited. This work presents a preliminary perspective of Quantitative Structure-Property Relationship (QSPR) modeling to assist in the targeted choice/design of active organocatalysts to produce cyclic carbonates. The QSPR was developed by applying the molecular descriptors (2D) to model the structure-property relationship between the organocatalysts features and its activity to produce oleochemical carbonates. From the virtual screening, a total of 122 catalysts have their activity predicted and the best molecular targets are proposed. The principal molecular features (organic structure, molecular arrangement, carbon chain size and substituent type) were identified through data mining, while the principal component analysis (PCA) proved to be suitable to perform the exploratory analysis of the molecules set. In addition, is presented the first report of the application of cetyltrimethylammonium bromide (CTAB) as a new catalyst to produce oleochemical carbonate derived from soy, canola and rice oils. The reactions were performed in a 50 cm3 stainless steel autoclave at 120?C, for 48 hours, without stirring, 5 MPa (p, CO2), 2 g of epoxidized oil, 4 mL of butanol and 5 mol% of CTAB. From the proposed method, all reactions showed more than 98% of epoxide conversion to cyclic carbonate for all the vegetable oil. In this way, the QSPR modelling can be applied to reduce the costs and time in the organocatalysts screening/design for the cyclic carbonates synthesis from CO2 and epoxides.
At? o momento, apenas um pequeno n?mero de organocatalisadores foram aplicados para produ??o de carbonatos oleoqu?micos, enquanto a descri??o de novos sistemas de catalisadores ainda ? limitada. O presente trabalho apresenta uma perspectiva preliminar da modelagem por Rela??o Quantitativa Estrutura-Propriedade (QSPR) para auxiliar na escolha/desenho de novos organocatalisadores para produ??o de carbonatos c?clicos. O QSPR foi desenvolvido aplicando os descritores moleculares (2D) para modelar a rela??o estrutura-propriedade entre as caracter?sticas dos organocatalisadores e sua atividade para produ??o de carbonatos oleoqu?micos. A partir da triagem virtual, um total de 122 catalisadores tiveram sua atividade prevista e os melhores alvos moleculares s?o propostos. As principais caracter?sticas moleculares (estrutura org?nica, arranjo molecular, tamanho da cadeia de carbono e tipo de substituinte) foram identificadas atrav?s da minera??o de dados, enquanto a an?lise de componentes principais (PCA) mostrou-se adequada para realizar a an?lise explorat?ria do conjunto de mol?culas. Al?m disso, ? apresentado o primeiro relato da aplica??o do brometo de cetiltrimetilam?nio (CTAB) como um catalisador para a produ??o de carbonato oleoqu?mico derivados dos ?leos de soja, canola e arroz. As rea??es foram realizadas em uma autoclave de a?o inoxid?vel de 50 cm3 a 120 ? C, durante 48 horas, sem agita??o, 5 MPa (p, CO2), 2 g de ?leo epoxidado, 4 mL de butanol e 5% molar de CTAB. A partir do m?todo proposto, todas as rea??es apresentaram mais de 98% de convers?o de ep?xido em carbonato c?clico para todos os ?leos vegetais. Desta forma, a modelagem QSPR pode ser aplicada para reduzir os custos e tempo na sele??o/desenho de organocatalisadores para a s?ntese de carbonatos c?clicos a partir de CO2 e ep?xidos.
Gaudin, Théophile. "Développement de modèles QSPR pour la prédiction et la compréhension des propriétés amphiphiles des tensioactifs dérivés de sucre." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2318/document.
Full textSugar-based surfactants are the main family of bio-based surfactants and are good candidates as substitutes for petroleum-based surfactants, since they originate from renewable resources and can show as good as, or even better, performances in various applications, such as detergent and cosmetic formulation, enhanced oil or mineral recovery, etc. Different amphiphilic properties can characterize surfactant performance in such applications, like critical micelle concentration, surface tension at critical micelle concentration, efficiency and Kraft point. Predicting such properties would be beneficial to quickly identify surfactants that exhibit desired properties. QSPR models are tools to predict such properties, but no reliable QSPR model was identified for bio-based surfactants, and in particular sugar-based surfactants. During this thesis, such QSPR models were developed. A reliable database is required to develop any QSPR model. Regarding sugar-based surfactants, no database was identified for the targeted properties. This motivated the elaboration of the first database of amphiphilic properties of sugar-based surfactants. The analysis of this database highlighted various empirical relationships between the chemical structure of these molecules and their amphiphilic properties, and enabled to isolate the most reliable datasets with the most homogeneous possible protocol, to be used for the development of the QSPR models. After the development of a robust strategy to calculate molecular descriptors that constitute QSPR models, notably relying upon conformational analysis of sugar-based surfactants and descriptors calculated only for the polar heads and for the alkyl chains, different QSPR models were developed, validated, and their applicability domain defined, for the critical micelle concentration, the surface tension at critical micelle concentration, the efficiency and the Kraft point. For the three first properties, good quantitative models were obtained. If the quantum chemical descriptors brought a significant additional predictive power for the surface tension at critical micelle concentration, and a slight improvement for the critical micelle concentration, no gain was observed for efficiency. For these three properties, simple models based on constitutional descriptors of polar heads and alkyl chains of the molecule (like atomic counts) were also obtained. For the Krafft point, two qualitative decision trees, classifying the molecule as water soluble or insoluble at room temperature, were proposed. The use of quantum chemical descriptors brought an increase in predictive power for these decision trees, even if a quite reliable model only based on constitutional descriptors of polar heads and alkyl chains was also obtained. At last, we showed how these QSPR models can be used, to predict properties of new surfactants before synthesis in a context of computational screening, or missing properties of existing surfactants, and for the in silico design of new surfactants by combining different polar heads with different alkyl chain
Couchaux, Gabriel. "Relation structure-propriété pour la cinétique de la réaction amine-CO2 en solution [i.e.solutions] aqueuses." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0206/document.
Full textThe post-combustion process by amine scrubbing is currently the most mature to reduce carbon dioxide emissions from industry. However, if there are numerous demonstrators, the investment and operating cost of this process are still too important to develop it in a large scale. The kinetics of reaction between the amine and the carbon dioxide is one of the major factor which influence the costs. The objectives of this work are to study and understand the kinetics of the amine-CO2 reaction and to set up of a predictive structure-property model. This approach is adapted to the large number of possible amines which can be candidates for the process. In a first time we study five kinds of amines (primary, acyclic secondary, cyclic secondary, tertiary and multi-amines) representatives of candidate molecules. Among those molecules, two behaviours can be distinguished: one the one hand amines which form carbamates and on the other hand those which do not form carbamates. Measurements have been realised at 25 °C in diluted solutions by stopped-flow technique to characterize the intrinsic kinetics of each of the 87 studied amines using two kinetic constants. For each kind of amine, the main structural factors, electronic and geometric, which impact the kinetics of reaction have been identified. Then, from a statistical model using molecular descriptors to describe the different parameters of each amine, a structure-property relationship has been set up with the different kinetic constants. A descriptor of the steric hindrance has been developed
Dimitriadis, Spyridon. "Multi-task regression QSAR/QSPR prediction utilizing text-based Transformer Neural Network and single-task using feature-based models." Thesis, Linköpings universitet, Statistik och maskininlärning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-177186.
Full textLangeron, Julie. "Etablissement d’une relation de type structure-propriétés (QSPR) entre les propriétés des pesticides et deux sols de Champagne crayeuse." Thesis, Reims, 2012. http://www.theses.fr/2012REIMS023/document.
Full textThis work is a part of the multidisciplinary AQUAL research program, which aims at to strive against diffuse pollutions in rural environment. It also took part in the Phyt'Eau Ref program initiated by the “Chambre Régionale d'Agriculture de Champagne-Ardenne”. It deals with the comprehension of retention and transfer of pesticides from soil to groundwaters in Champagne-Ardenne. Two different soils by their organic matter and calcite contents, were chosen to carry out the study in order to evaluate the behavior of pesticides in characteristic soils of the region (pH and calcite content). The study was carried out on forty pesticides from various chemical families and having different physico-chemical properties. The aim was to identify the physico-chemical properties of pesticides governing their retention in soils and then to establish a quantitative structure properties relationship (QSPR) predicting the adsorption coefficient Kd. Adsorption and transfer of pesticides were studied in laboratory through batch experiments (equilibrium study) and soil column reconstituted in laboratory. Adsorption isotherm plot followed by a statistical analysis allowed identifying hydrophobicity, polarisability and solubility as the main physico-chemical parameters correlated to the pesticide retention. Relations combining two of these parameters were proposed and tested in order to predict the pesticide adsorption coefficient. Finally, studies in dynamic mode (column) allowed to evidence that the transfer phenomenon can be correlated to the pesticide adsorption nd that it was possible to go from one to the other parameters describing these two phenomena by simple linear relations, allowing to get rid of onerous experiences
Arruda, Anna Celia. "Ampliação e aplicação do método semi-empírico topológico (IET) em modelos QSRR/QSPR/QSAR para compostos alifáticos halogenados e cicloalcanos." Florianópolis, SC, 2008. http://repositorio.ufsc.br/xmlui/handle/123456789/91111.
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Este estudo foi desenvolvido para avaliar a capacidade de prognóstico do índice semi-empírico topológico (IET) em estimar a retenção cromatográfica (IR) de compostos alifáticos halogenados e cicloalcanos. Também foram desenvolvidos modelos de QSPR/QSAR para prever importantes propriedades físico-químicas, termodinâmicas e atividades biológicas. O modelo de QSRR do IRExpde 141 haloalcanos e o IET mostrou boa qualidade estatística (r2=0,9995; SD=8; r2cv=0,999). A partir do modelo de QSPR obtido entre o ponto de ebulição, Bp(ºC), com o IET (N=86; r2=0,9971; SD=4,2; r2cv=0,997), foram calculados os valores para um grupo externo de 24 compostos (r2=0,9931; SD=7,6). Uma boa correlação entre o ponto de fusão, Mp (°C), e o IET foi obtida (N=43; r2=0,9865; SD=6,1; r2cv=0,985). As correlações obtidas entre os valores calculados e experimentais de log P foram de r2=0,9871 e r2=0,9750, respectivamente para os Métodos Semi-Empírico Topológico e Contribuição dos Fragmentos. Esses resultados mostram a capacidade de prognóstico do IET para propriedades físico-químicas e termodinâmicas. A habilidade de prognóstico do IR pelo IET também foi verificada usando fases estacionárias com diferentes polaridades. Resultados satisfatórios foram encontrados aplicando o IET para estimar o IR de 48 cicloalcanos (r2=0,9905; SD=7; r2cv=0,997) e Bp(°C) (N=33; r2cv=0,988). Esse método permitiu retirar informações sobre as características estruturais, eletrônicas e geométricas das moléculas que estão influenciando no processo de retenção cromatográfico e a distinção entre isômeros cis/trans dos compostos estudados.
Saraf, Sanjeev R. "Molecular characterization of energetic materials." Texas A&M University, 2003. http://hdl.handle.net/1969.1/331.
Full textMoreira, Bastos Patricia. "Comparison of experimentally and theoretically determined oxidation and photochemical transformation rates of some organohalogens to promote prediction of persistence." Doctoral thesis, Stockholms universitet, Institutionen för miljökemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-26040.
Full textDureckova, Hana. "Robust Machine Learning QSPR Models for Recognizing High Performing MOFs for Pre-Combustion Carbon Capture and Using Molecular Simulation to Study Adsorption of Water and Gases in Novel MOFs." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37288.
Full textReis, Ralpho Rinaldo dos. "Modelos de predição do coeficiente de sorção no solo de pesticidas não iônicos: diferentes algoritmos de logP e uma abordagem alternativa de logS." Universidade Estadual do Oeste do Parana, 2013. http://tede.unioeste.br:8080/tede/handle/tede/166.
Full textCollecting data on pesticide effects on the environment and several ecosystems is a slow and costly process. Therefore, significant research efforts have been focused on developing mathematical models to predict physical, chemical or biological properties of environmental interest. The soil sorption coefficient normalized to organic carbon content (Koc) is a physicochemical key parameter used in environmental risk assessments of substances released into the environment. Thus, several logKoc prediction models that use hydrophobic parameter (logP) or the logarithm of water solubility (logS) as descriptor have been reported in the last decades. Mostly, due to the lack of reliable experimental values of logP or logS, algorithms are used to calculate such properties. Despite the availability and easiness to access several algorithms for this purpose, scientific studies do not describe the procedure adopted to choose the algorithm used in quantitative structure-property relationship (QSPR) studies. Furthermore, the strong correlation between logP and logS prevents their application in the same mathematical equation obtained by multiple linear regression method. Since the sorption process of a chemical compound in soil is related both to its water solubility and its water/organic matter partition, it is expected models that are able to combine these two properties will can record more realistic results. This doctoral dissertation consists of two scientific papers. In the first one, a study was carried out to check the influence of choosing logP algorithm on logKoc modeling. Models were constructed to relate logKoc with logP according to different freeware algorithms. All models were assessed based on their statistic qualities and predictive power. The obtained results clearly showed that an arbitrary choice of the algorithm may not result in the best prediction model. On the other hand, a good choice can lead to obtaining simple models with statistic qualities and predictive power comparable to more complex models. The second paper aims at proposing an alternative approach for logKoc modeling, using simple descriptor of solubility, here referred as logarithm of corrected solubility by octanol/water partition (logSP). Thus, models were built with this descriptor and also with logP and logS conventional descriptors, which are isolated or associated with other explicative variables of easy physicochemical interpretation. The obtained models were validated and compared to other models previously published. The results showed that the use of logSP descriptor to replace the conventional ones led to obtaining simple models with statistic qualities and predictive power that are higher than other more complex models already found in literature.
A coleta de dados relativos aos danos causados pelos pesticidas sobre o meio ambiente e seus ecossistemas é lenta e onerosa. Desta maneira, grandes incentivos têm sido destinados às pesquisas que visam à construção de modelos matemáticos para predição de propriedades físicas, químicas ou biológicas de interesse ambiental. O coeficiente de sorção no solo normalizado para o conteúdo de carbono orgânico (Koc) é um importante parâmetro físico-químico utilizado nas avaliações de riscos ambientais das substâncias lançadas no meio ambiente. Assim, vários modelos para predição de logKoc, utilizando o parâmetro hidrofóbico (logP) ou o logaritmo da solubilidade em água (logS) como descritores, têm sido publicados nas últimas décadas. Muitas vezes, em virtude da ausência de valores experimentais confiáveis de logP ou logS, são usados algoritmos para o cálculo dessas propriedades. Apesar da disponibilidade e facilidade de acesso a diversos algoritmos para tal finalidade, os artigos científicos não descrevem o procedimento adotado para escolha do algoritmo usado nos estudos QSPR. Além disto, a forte correlação entre logP e logS impede que sejam usados em uma mesma equação obtida por regressão linear múltipla. Como o processo de sorção de um composto químico no solo está relacionado tanto com sua solubilidade em água como com sua partição água/matéria orgânica, espera-se que modelos que sejam capazes de combinar essas duas informações possam gerar resultados mais realistas. Este trabalho de tese é constituído de dois artigos. No primeiro artigo, foi feito um estudo para verificar a influência da escolha do algoritmo de logP na modelagem de logKoc. Foram construídos modelos que relacionam logKoc com logP a partir de diferentes algoritmos livres disponíveis. Todos os modelos foram avaliados quanto às suas qualidades estatísticas e poder de predição. Os resultados obtidos mostraram claramente que uma escolha arbitrária deste algoritmo pode não levar ao melhor modelo de predição. Por outro lado, uma boa escolha pode conduzir à obtenção de modelos simples com qualidades estatísticas e poder de predição comparáveis a de modelos mais complexos. No segundo artigo, o objetivo foi a proposição de uma abordagem alternativa para a modelagem de logKoc, utilizando um descritor simples de solubilidade, aqui designado como logaritmo da solubilidade corrigida pela partição octanol/água (logSP). Assim, foram construídos modelos com tal descritor e também com os descritores convencionais logP e logS, isolados ou associados com outras variáveis explicativas de fácil interpretação físico-química. Os modelos obtidos foram validados e comparados com outros modelos publicados anteriormente. Os resultados mostraram que o uso do descritor logSp em substituição aos descritores convencionais conduziu à obtenção de modelos simples com qualidades estatísticas e poder de predição superiores a de outros modelos mais complexos encontrados na literatura.
Alexandre, Mike Abidine. "Optimisation du comportement mécanique de composites structuraux PEKK/Fibres de carbone par ensimage oligomères de PEKK." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30207.
Full textThe objective of this research is to design and analyze a sizing for PEKK / continuous carbon fiber (CF) structural composites. PEKK oligomers (oPEKK) were synthesized in the laboratory to define the physicochemical characteristics allowing their use as a sizing agent. From these specifications, a "pilot" oligomer was synthesized in order to carry out studies on the sizing formulation. From a study of quantitative structure-property relationship (QSPR) and artificial neural networks (ANN), the development and optimization of a "solvent-free" sizing formulation was performed. The deposit of this sizing was achieved according to two protocols: we thus produced a "laboratory sizing" and "pilot sizing". Mechanical performances of PEKK / CF without and with oPEKK sizing composites were studied by dynamic mechanical analysis (DMA). Whatever the protocol is, the sizing optimizes the mechanical performances significantly. It is interesting to note that "pilot sizing" is more efficient than "laboratory sizing". Besides the advantage of sizing for fiber placement in composite processing, the fiber / matrix stress transfer is optimized. Then, it results in an increase of both storage and loss modulus
Stöcker, Hartmut. "Struktur-Eigenschafts-Korrelationen in Strontiumtitanat." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-78565.
Full textBeing a model system for oxides with pervovskite-type of structure, strontium titanate can be used to gain generalizable insights into the consequences of defects and to discuss resulting structure-property relationships. By employing different surface sensitive methods, an increased concentration of line defects is found at the surface that reduces on temperature treatment. The defect chemistry at elevated temperatures is used to simulate the electric conductivity depending on the oxygen partial pressure during annealing. Doping of the oxidic semiconductor depends on intrinsic defects, whereby oxygen vacancies form donor states and strontium vacancies have acceptor character. Beside the diffusion movement of these intrinsic defects at elevated temperatures, at low temperatures an electric field may cause their redistribution. Hence, the conductivity becomes dependent on external electric fields but also other properties can be altered in this way. Within this work, structural changes, valence changes and changing mechanical properties are shown to be switchable by the electric field. Finally, the dedicated usage of structural defects is demonstrated on memory cells that employ the switchable resistance of metal-SrTiO3 junctions. The applicability of the oxidic semiconductor as a resistive memory element is again based on the coupling between oxygen vacancies and the electric field
Youmbi, Foka Marcel [Verfasser], Tim [Akademischer Betreuer] Clark, Tim [Gutachter] Clark, and Birgit [Gutachter] Strodel. "3D-QSAR/QSPR Based Surface-Dependent Modeling Approach Derived From Semi-Empirical Quantum Mechanical Calculations / Marcel Youmbi Foka ; Gutachter: Tim Clark, Birgit Strodel ; Betreuer: Tim Clark." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1175206490/34.
Full textCypcar, Christopher Charles. "Investigation of structure-property relationships of nylon 6-co-7 and linear alkyl model amide compounds and molecular modeling quantitative structure-property relationship (QSPR) for glass temperature predictions." Aix-Marseille 3, 1997. http://www.theses.fr/1997AIX30035.
Full textMerabtine, Yacine. "Etude des relations entre la structure des molécules odorantes et leurs équilibres rétention-libération entre phase vapeur et gels laitiers." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00583420.
Full textLuca, Aurélie de. "Espaces chimiques optimaux pour la recherche par similarité, la classification et la modélisation de réactions chimiques représentées par des graphes condensés de réactions." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF027.
Full textThis thesis aims to develop an approach based on the Condensed Graph of Reaction (CGR) method able to (i) select an optimal descriptor space the best separating different reaction classes, and (ii) to prepare special descriptors to be used in obtaining predictive structure-reactivity models. This methodology has been applied to similarity search studies in a database containing 8 different reaction classes, and to visualization of its chemical space using Kohonen maps and Generative Topographic Mapping. Another part of the thesis concerns development of predictive models for pKa and for optimal conditions for different types of Michael reaction involving both CGR-based and Electronic Effect Descriptors
Liu, Jiangping. "Prediction of Fluid Dielectric Constants." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2787.
Full textLukowicz, Thomas. "Synergistic solubilisation of fragrances in binary surfactant systems and prediction of their EACN value with COSMO-RS." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10090/document.
Full textSolvo-surfactants are a relatively new class of amphiphiles, which exhibit properties of both, surfactants and solvents. They are able to form aggregates, wherein they can solubilise hydrophobic compounds. Furthermore they exhibit volatile characteristics, which make them interesting for applications where volatility is a key factor, such as aqueous fragrance solubilisations. In a solvo-surfactant/oil/water (SOW) system, the phase behaviour is strongly influenced by the hydrophobicity of the oil. Therefore the equivalent alkane carbon number (EACN) of several polar oils, such as dialkylethers, 2-alkanones, 1-chloroalkanes etc. was determined and the decrease in EACN with respect to n-alkanes was related to its functionalization, as well as rationalised with the effective packing parameter for each corresponding type of oil. The EACN of all 94 oils were then used in a multilinear regression analysis, based on COSMO-RS -moments, in order to establish a QSPR model, which is able to predict the EACN of any hydrocarbon oil. The influence of ionic surfactants was finally investigated in a SOW system, with various oils of different EACN. It was found that the ionic surfactant increases strongly the temperature stability of the (pseudo-)ternary system, as well as the efficiency to solubilise the oil. However the efficiency undergoes a maximum for a certain molar fraction of ionic surfactant, since the latter prevents the system to inverse. Thus a bicontinuous microemulsion cannot be formed, which is known to solubilise high amounts of oil and water
Enot, David. "La modélisation moléculaire en tant qu'outil prédictif et de compréhension du comportement thermotrope et lyotrope de sucres. Approche QSPR de la lipophilie de 1,2-dithiole-3-thiones et 1,2-dithiole-3-ones." Rennes 1, 2001. http://www.theses.fr/2001REN10117.
Full textFourches, Denis. "Modèles multiples en QSAR/QSPR : Développement de nouvelles approches et leurs applications au design "in silico" de nouveaux extractants de métaux, aux propriétés ADMETox ainsi qu'à différentes activités biologiques de molécules organiques." Université Louis Pasteur (Strasbourg) (1971-2008), 2007. http://www.theses.fr/2007STR13119.
Full textThis thesis work concerns the improvement of prediction performances of QSAR structureproperty models, using consensus modelling strategies based on fragment descriptors, and also, to their applications for « in silico » design of metal binders, ADMETox properties and different biological activities of organic compounds. In the first part, some important concepts and methodologies of chemoinformatics are described. In the second part, the ensemble of programs ISIDA (In Silico Design and Data Analysis) is introduced. During this thesis work, two consensus approaches have been suggested: the « Divide and Conquer » strategy and the Stepwise k- Nearest Neighbors approach. Applications of new strategies lead to significant improvement of predictions accuracy, compared to the conventional models. In the third part, all ISIDA methods have been successfully applied to model various chemical and biological properties. Experimentally proven predictions demonstrate the robustness of the methods