• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 16
  • 8
  • 5
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 42
  • 24
  • 11
  • 7
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vstup firmy na zahraniční trh / Company enters a foreign market

Janečková, Petra January 2011 (has links)
The aim of the diploma thesis was to describe the conditions of entry Holidays Czech Airlines the Icelandic market, specifically the establishing of direct air service from Prague to Keflavik. The thesis is divided into six chapters, which are devoted to both theoretical expectations for companies entering foreign markets, and practical sections. The general reasons which lead a company to expansion and the associated risks are described in the first chapter as well as the macroeconomic analysis of the market, the PESTEL analysis, which I used to analyze the Icelandic market. The second chapter discusses the various forms of entry the foreign markets and compares their advantages and shortcomings. The third chapter was related to the specific cooperation of airlines. The practical part of the thesis introduces companies HCA and IEX, focuses primarily on the evaluation of HCA Company based on the SWOT analysis. The following chapter is devoted to cooperation of mentioned companies. The final chapter evaluates the Icelandic market using the above mentioned PESTEL analysis.
2

Polycyclic aromatic hydrocarbons in the sediments of the coastal areas along the southwestern Taiwan.

Wang, Chih-ying 05 August 2005 (has links)
The objective of this study is to quantify the polycyclic aromatic hydrocarbons (PAHs) of the sediments along the coast of south-western Taiwan and to investigate possible sources. The south-western coastal area is full of heavy industries. There are tens of industrial parks along with export processing zone, steel-making plant, oil refinery, shipbuilding plant, Hsin-ta pelagic fishing port, Hsin-ta thermal power plant and Kaohsiung international port. It is reasonable that the wastewater went into rivers or pipes and eventually enters coast area. Concentrations of total polycyclic aromatic hydrocarbons (PAHs) in the sediments of south-western Taiwan were between 197.3~2498.9 (ng/g ¡Vdw) with the average of 912.0 (ng/g ¡V dw). Among all stations sampled in this study, A3, located at the waterway of Kaohsiung, has the highest value. The wastewater ejected by ships might be the major factor. The second highest value we got is from C2, which located at the area farer from shoreline than A3. Total organic carbon (TOC) versus median particle size has linear relationship, however, total organic carbon (TOC) versus concentrations of polycyclic aromatic hydrocarbons (PAHs) showed no linear relationship. This is probably due to the wide sampling area of this study and sources of polycyclic aromatic hydrocarbons (PAHs) were not the same. Principal component analysis shows three principal components were extracted and up to 78.79% of total variance can be explained. As indicated on rotated loadings, the three major components were characterized by 4-6 rings PAH compounds, 3-4 rings PAH compounds and 2-5 rings PAHs compounds, respectively. Results of Hierachical cluster analysis also show three major groups (Group 1, 2 and 3) can be geographically related. In addition, according to isomer ratios of PAH compounds, pollution sources of each group can be specified. Group 1, stations located northern bound, has mainly pyrogenic pollution sources, while Group2, stations located at central area of this study, has pyrogenic/petrogenic sources. For Group 3, stations located southern bound, was mainly polluted by petroleum. In regards to the sediment quality guidelines, ERL and ERM, there are one third of stations exceed ERL regarding to Acp and Phe, but only station A3 exceeds ERL regarding to F1 and Pyr.
3

Multi material topology optimization with hybrid cellular automata

Solis Ocampo, Jennifer January 2017 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Topology Optimization is a technique that allows for the obtaining structures which maximize the use of the material. This is done by intelligently deciding the binary distribution of solid material and void, in a discretized given space. Several researchers have provided methods to tackle binary topology optimization. New ef- forts are focused on extending the application for multi-phase optimizations. At the industrial level, several components designed are made up of more than one material to reduce weight and production costs. The objective of this work is to implement the algorithm of Hybrid Cellular Automaton for multi-material topology optimiza- tion. The commonly used interpolation rule SIMP, which allows to relate the design variables to the mechanical properties of the material, is replaced by ordered SIMP interpolation function. The multiple volume constraints are applied sequentially, starting with the most elastic material. When a constraint is satisfied, the elements assigned to this material remain passive by a defined number of iterations to promote the convergence of the solution. Examples are shown for static and dynamic loads. The work demonstrates the versatility of algorithms based on control systems to solve problems of multiple phases and transient response fields.
4

Physiological, biochemical and molecular characterisation of hydroxycinnamic acid catabolism by Dekkera and Brettanomyces yeasts.

Harris, Victoria January 2010 (has links)
Dekkera and the closely related Brettanomyces are important yeasts in food and beverage production in part due to the metabolism of hydroxycinnamic acids (HCAs). There is a dearth of information concerning the role Brettanomyces spp. play in the food or beverage from which they are isolated and although Dekkera spp. have been investigated further there are discrepancies and questions yet to be answered. Representatives of both genera were examined to define growth and metabolism of individual HCAs in synthetic media. In addition, growth with combinations of HCAs was investigated for the first time. The results provide a comprehensive overview of HCA metabolism and volatile product formation for these genera. Furthermore, results have been confirmed in a semidefined wine medium that more closely resembled the physio-chemical parameters found in the typical wine environment. The enzymes responsible for the metabolism of HCAs were examined in Dekkera and Brettanomyces. Dekkera yeasts are known to enzymatically convert HCAs into vinylphenols (VPs) and ethylphenols (EPs). These products are indicative of Dekkera contamination. The first enzyme in the two-step HCA ─ VP ─ EP biochemical pathway is a hydroxycinnamic acid decarboxylase (HCD). This enzyme has been previously characterised from a single Dekkera strain. The second enzyme, vinylphenol reductase (VPR) has never been isolated or characterised from any microorganism. In order to further elucidate the HCA ─ VP ─ EP pathway, cell extracts were prepared from all five Dekkera and Brettanomyces spp. to evaluate activity against HCAs and VPs. Brettanomyces spp. were unable to metabolise HCAs indicating that these yeast do not have a functional HCD enzyme. Both Dekkera spp. have substrate inducible HCD activity. Temperature and pH optima were 40ºC and 5.75-6.00, respectively. The active protein was purified from cell extracts of D. anomala CBS 77 and a partial sequence was obtained. 3’RACE PCR was performed and a near complete gene sequence determined. This sequence does not have homology to HCA decarboxylase enzymes previously characterised from yeasts and bacteria and thus may represent a novel enzyme not previously described. Biochemical characterisation of the vinylphenol reductase (VPR) enzyme was also undertaken. VPR activity was found for all 5 Dekkera and Brettanomyces spp. Activity was greatest at pH 6 and between 40-50ºC and was induced by both VPs and HCAs. Data obtained during growth experiments indicated that HCAs, and in particular ferulic acid, inhibited the growth of Dekkera and Brettanomyces spp. On this basis a more detailed study was carried out to determine the concentrations required to prevent growth in various media. In a modified red wine a concentration 0.1 mM ferulic acid inhibited growth and 2 mM prevented cultures of both D. anomala and D. bruxellensis from becoming established even when re-inoculated into to a fresh HCA-free medium. Scanning electron micrographs revealed that ferulic acid caused physical damage to Dekkera cells upon exposure. This work could lead to the development of an alternative method for the control of Dekkera in wine or other food products. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1454852 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2010
5

Avaliação da contaminação nos principais corpos d\'água do município de São Carlos/SP / Assessment of the contamination of the main water bodies in São Carlos/SP

Baio, José Augusto Fragale 18 November 2009 (has links)
Os corpos d\'água do município de São Carlos/SP recebem esgotos domésticos, efluentes industriais e agrícolas, de tal forma que se propôs neste trabalho a identificação de possíveis correlações entre a contaminação antropogênica dos cursos d\'água com as fontes poluidoras. Escolheram-se 27 pontos de amostragem - localizados de maneira estratégica - para analisarem-se os parâmetros: pH, condutividade, oxigênio dissolvido, temperatura e sólidos totais dissolvidos, na água; nutrientes (nitrogênio total Kjeldahl, fósforo total e carbono orgânico) e metais (Cr, Cu, Mn, Fe, Co, Ni, Cd, Pb, Zn e Al) na água e nos sedimentos; além de ânions (F-, Cl-, Br-, NO2-, NO3-, SO42- e PO43-) e cátions (Li+, Na+, K+, NH4+, Mg2+ e Ca2+) na água. A partir do conjunto de dados obtidos das análises, propôs-se o cálculo de um índice de qualidade (IQASC), de modo que pudesse ser feita a quantificação da qualidade da água destes cursos d\'água nos períodos das chuvas (verão) e das secas (inverno). Observou-se através dos valores dos índices que a sazonalidade é muito importante na qualidade dos cursos d\'água do município, de modo que no período das chuvas a qualidade da água é melhor do que no período das secas na maioria dos pontos de coleta. Utilizou-se a correlação de Spearman para distinguir se nutrientes, íons e metais poderiam vir da mesma fonte de poluição ou se os mesmo são devidos a contribuições naturais dos solos. Fizeram-se análises quimiométricas (HCA e PCA) com intenção de uma melhor interpretação dos resultados, pois o grande conjunto de dados dificultava a visualização dos mesmos. O método do \"refolding\" da matriz aumentada foi importante para, a partir dos parâmetros analisados, separarem-se os escores geográficos dos temporais. Através da HCA, obteve-se a separação da maioria dos grupos segundo as campanhas de amostragem, de tal forma que apenas em um ou dois dos grupos, no máximo, ocorreu à mistura de pontos de diferentes épocas de coleta. Na PCA, diferenciaram-se alguns grupos de amostras, a partir dos quais se pôde descobrir quais dos parâmetros analisados eram devidos a contaminação antropogênica ou contribuição natural dos solos. Através da análise dos resultados, pôde-se concluir que os pontos do Córrego do Gregório dentro do perímetro urbano, do Córrego do Tijuco Preto próximos da nascente, do Córrego Água Quente após receber o esgoto do bairro Cidade Araci e alguns pontos do Rio Monjolinho estão impactados pela presença de esgoto doméstico. / The water bodies of São Carlos/SP receive domestic sewage besides industrial and agricultural wastewaters, so that it was proposed in this work the identification of possible correlations between the waterways anthropogenic contamination and the pollution sources. Twenty-seven sampling points were chosen - strategically located - in order to analyze the following parameters: pH, conductivity, dissolved oxygen, temperature, and total dissolved solids in the water; nutrients (total Kjeldahl nitrogen, total phosphorus, and organic carbon) and metals (Cr, Cu, Mn, Fe, Co, Ni, Cd, Pb, Zn, and Al) in the water and sediments; anions (F-, Cl-, Br-, NO2-, NO3-, SO42- e PO43-) and cations (Li+, Na+, K+, NH4+, Mg2+ e Ca2+) in the water. From the set of data obtained in the analyses, it has been proposed the calculation of a quality index (IQASC), so that the quantification of the water quality could be performed, during the summer (rainy weather) and the winter (dry weather). It was observed through the values of the indices that the seasonality is very important for the quality of watercourses in the city, so that during the rainy season the water quality is better than in the dry one in the majority of the sampling points. The Spearman correlation was used in order to distinguish if nutrients, ions, and metals could come from the same source of pollution or if the contributions are of naturally origin. Chemometric analyses (HCA and PCA) were also performed for better interpreting the results, due to the large amount of data. The method of refolding the augmented matrix was important for, through the analyzed data, separating geographical and temporal scores. Through the HCA, the separation of the majority of the groups according to the sampling campaigns was achieved. In one or two groups only the mixture of sampling campaigns were observed. The PCA differentiated some groups of samples, allowing the association of the parameters to anthropogenic or natural sources. By analyzing the obtained results, it could be concluded that the Gregório Stream (inside the urban perimeter), the Tijuco Preto Stream (near its spring), the Água Quente Stream after receiving the sewage of Cidade Araci Suburb, and some points of Monjolinho River are impacted by the presence of domestic sewage.
6

Avaliação da contaminação nos principais corpos d\'água do município de São Carlos/SP / Assessment of the contamination of the main water bodies in São Carlos/SP

José Augusto Fragale Baio 18 November 2009 (has links)
Os corpos d\'água do município de São Carlos/SP recebem esgotos domésticos, efluentes industriais e agrícolas, de tal forma que se propôs neste trabalho a identificação de possíveis correlações entre a contaminação antropogênica dos cursos d\'água com as fontes poluidoras. Escolheram-se 27 pontos de amostragem - localizados de maneira estratégica - para analisarem-se os parâmetros: pH, condutividade, oxigênio dissolvido, temperatura e sólidos totais dissolvidos, na água; nutrientes (nitrogênio total Kjeldahl, fósforo total e carbono orgânico) e metais (Cr, Cu, Mn, Fe, Co, Ni, Cd, Pb, Zn e Al) na água e nos sedimentos; além de ânions (F-, Cl-, Br-, NO2-, NO3-, SO42- e PO43-) e cátions (Li+, Na+, K+, NH4+, Mg2+ e Ca2+) na água. A partir do conjunto de dados obtidos das análises, propôs-se o cálculo de um índice de qualidade (IQASC), de modo que pudesse ser feita a quantificação da qualidade da água destes cursos d\'água nos períodos das chuvas (verão) e das secas (inverno). Observou-se através dos valores dos índices que a sazonalidade é muito importante na qualidade dos cursos d\'água do município, de modo que no período das chuvas a qualidade da água é melhor do que no período das secas na maioria dos pontos de coleta. Utilizou-se a correlação de Spearman para distinguir se nutrientes, íons e metais poderiam vir da mesma fonte de poluição ou se os mesmo são devidos a contribuições naturais dos solos. Fizeram-se análises quimiométricas (HCA e PCA) com intenção de uma melhor interpretação dos resultados, pois o grande conjunto de dados dificultava a visualização dos mesmos. O método do \"refolding\" da matriz aumentada foi importante para, a partir dos parâmetros analisados, separarem-se os escores geográficos dos temporais. Através da HCA, obteve-se a separação da maioria dos grupos segundo as campanhas de amostragem, de tal forma que apenas em um ou dois dos grupos, no máximo, ocorreu à mistura de pontos de diferentes épocas de coleta. Na PCA, diferenciaram-se alguns grupos de amostras, a partir dos quais se pôde descobrir quais dos parâmetros analisados eram devidos a contaminação antropogênica ou contribuição natural dos solos. Através da análise dos resultados, pôde-se concluir que os pontos do Córrego do Gregório dentro do perímetro urbano, do Córrego do Tijuco Preto próximos da nascente, do Córrego Água Quente após receber o esgoto do bairro Cidade Araci e alguns pontos do Rio Monjolinho estão impactados pela presença de esgoto doméstico. / The water bodies of São Carlos/SP receive domestic sewage besides industrial and agricultural wastewaters, so that it was proposed in this work the identification of possible correlations between the waterways anthropogenic contamination and the pollution sources. Twenty-seven sampling points were chosen - strategically located - in order to analyze the following parameters: pH, conductivity, dissolved oxygen, temperature, and total dissolved solids in the water; nutrients (total Kjeldahl nitrogen, total phosphorus, and organic carbon) and metals (Cr, Cu, Mn, Fe, Co, Ni, Cd, Pb, Zn, and Al) in the water and sediments; anions (F-, Cl-, Br-, NO2-, NO3-, SO42- e PO43-) and cations (Li+, Na+, K+, NH4+, Mg2+ e Ca2+) in the water. From the set of data obtained in the analyses, it has been proposed the calculation of a quality index (IQASC), so that the quantification of the water quality could be performed, during the summer (rainy weather) and the winter (dry weather). It was observed through the values of the indices that the seasonality is very important for the quality of watercourses in the city, so that during the rainy season the water quality is better than in the dry one in the majority of the sampling points. The Spearman correlation was used in order to distinguish if nutrients, ions, and metals could come from the same source of pollution or if the contributions are of naturally origin. Chemometric analyses (HCA and PCA) were also performed for better interpreting the results, due to the large amount of data. The method of refolding the augmented matrix was important for, through the analyzed data, separating geographical and temporal scores. Through the HCA, the separation of the majority of the groups according to the sampling campaigns was achieved. In one or two groups only the mixture of sampling campaigns were observed. The PCA differentiated some groups of samples, allowing the association of the parameters to anthropogenic or natural sources. By analyzing the obtained results, it could be concluded that the Gregório Stream (inside the urban perimeter), the Tijuco Preto Stream (near its spring), the Água Quente Stream after receiving the sewage of Cidade Araci Suburb, and some points of Monjolinho River are impacted by the presence of domestic sewage.
7

Aplicação da química quântica ao estudo de um grupo de moléculas antihistamínicas H3 / A quantum chemical study on a set of H3 antihistamine molecules

Edson Barbosa da Costa 10 February 2010 (has links)
Nesta tese foi estudado um grupo de 28 compostos não-imidazólicos antagonistas do receptor H3 através de cálculos de orbitais moleculares utilizando os métodos de química quântica Austin Model 1, Hartree-Fock-Roothaan e Teoria do Funcional da Densidade com o objetivo de investigar possíveis relações entre descritores eletrônicos teóricos e as afinidades ligantes experimentais desses compostos (pKi). Observou-se nos resultados obtidos que as energias dos orbitais FERMOs (Frontier Effective-for-Reaction Molecular Orbitals) apresentam melhor correlação com os valores de pKi do que as energias dos orbitais de fronteira HOMO (Highest Occupied Molecular Orbital) e LUMO (Lowest Unoccupied Molecular Orbital). Além disso, verificou-se pelas análises de métodos multivariados PCA (Principal Componente Analysis) e HCA (Hierarchical Cluster Analysis) que um conjunto de quatro descritores foi capaz de separar os compostos em dois grupos distintos, o primeiro que apresenta valores de afinidades ligantes maiores e o segundo com menores valores de pKi. Esta separação foi possível com o uso dos seguintes descritores teóricos: energia do FERMO (εFERMO), carga derivada do potencial eletrostático no átomo de nitrogênio N1, índice de densidade eletrônica no átomo N1 (Σ(FERMO) ci2) e eletrofilicidade (ω\'). Estes descritores foram utilizados, posteriormente, para a construção de três equações de regressão pelo método PLS (Partial Least Squares). O melhor modelo de regressão gerou os seguintes parâmetros estatísticos Q2 = 0,88 e R2 = 0,927, obtidos com um conjunto treino e de validação externa de 23 e 5 moléculas, respectivamente. Logo após a avaliação da equação de regressão, juntamente com os valores dos descritores selecionados e outros não selecionados, foi sugerido que altos valores de energias dos FERMOs e de Σ(FERMO) ci2 em conjunto com baixos valores de eletrofilicidades e cargas extremamente negativas no átomo N1 são parâmetros relevantes para potencializar as afinidades ligantes de outros compostos a serem sintetizados, que apresentem estruturas químicas semelhantes às moléculas estudadas neste trabalho. Além disso, esses compostos podem ser considerados como doadores de elétrons e, logo, há uma grande probabilidade que tais moléculas interajam com o receptor histamínico H3 a partir de um processo de transferência de carga. / In this thesis, molecular orbital calculations were carried out on a set of 28 non-imidazole H3 antihistamine compounds using Austin Moldel 1, Hartree-Fock-Roothaan, and Density Functional Theory methods in order to investigate the possible relationships between electronic descriptors and binding affinity for H3 receptors (pKi). It was observed that the frontier effective-for-reaction molecular orbital (FERMO) energies were better correlated with pKi values than HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) energy values. Exploratory data analysis through hierarchical cluster (HCA) and principal component analysis (PCA) showed a separation of the compounds into two sets by using four descriptors, one grouping the molecules with high pKi values, the other gathering low pKi value compounds. This separation was obtained with the use of the following descriptors: FERMO energies (εFERMO), charges derived from the electrostatic potential on the nitrogen atom (N1), electronic density indexes for FERMO on the N1 atom (Σ(FERMO) ci2), and electrophilicity (ω\'). These electronic descriptors were used to construct three quantitative structure-activity relationship (QSAR) models through the Partial Least Squares Method (PLS). The best model generated Q2 = 0.88 and R2 = 0.927 values obtained from a training set and external validation of 23 and 5 molecules, respectively. After the analysis of the PLS regression equation, the values for the selected electronic descriptors and other descriptors, it is suggested that high values of FERMO energies and of Σ(FERMO) ci2, together with low values of electrophilicity and pronounced negative charges on N1 appear as desirable properties for the conception of new molecules which might have high binding affinity. Moreover, these molecules can be classified as electron donating compounds and have a great probability of interacting through a charge transfer process with the biological receptor H3.
8

Aplicação da química quântica ao estudo de um grupo de moléculas antihistamínicas H3 / A quantum chemical study on a set of H3 antihistamine molecules

Costa, Edson Barbosa da 10 February 2010 (has links)
Nesta tese foi estudado um grupo de 28 compostos não-imidazólicos antagonistas do receptor H3 através de cálculos de orbitais moleculares utilizando os métodos de química quântica Austin Model 1, Hartree-Fock-Roothaan e Teoria do Funcional da Densidade com o objetivo de investigar possíveis relações entre descritores eletrônicos teóricos e as afinidades ligantes experimentais desses compostos (pKi). Observou-se nos resultados obtidos que as energias dos orbitais FERMOs (Frontier Effective-for-Reaction Molecular Orbitals) apresentam melhor correlação com os valores de pKi do que as energias dos orbitais de fronteira HOMO (Highest Occupied Molecular Orbital) e LUMO (Lowest Unoccupied Molecular Orbital). Além disso, verificou-se pelas análises de métodos multivariados PCA (Principal Componente Analysis) e HCA (Hierarchical Cluster Analysis) que um conjunto de quatro descritores foi capaz de separar os compostos em dois grupos distintos, o primeiro que apresenta valores de afinidades ligantes maiores e o segundo com menores valores de pKi. Esta separação foi possível com o uso dos seguintes descritores teóricos: energia do FERMO (εFERMO), carga derivada do potencial eletrostático no átomo de nitrogênio N1, índice de densidade eletrônica no átomo N1 (Σ(FERMO) ci2) e eletrofilicidade (ω\'). Estes descritores foram utilizados, posteriormente, para a construção de três equações de regressão pelo método PLS (Partial Least Squares). O melhor modelo de regressão gerou os seguintes parâmetros estatísticos Q2 = 0,88 e R2 = 0,927, obtidos com um conjunto treino e de validação externa de 23 e 5 moléculas, respectivamente. Logo após a avaliação da equação de regressão, juntamente com os valores dos descritores selecionados e outros não selecionados, foi sugerido que altos valores de energias dos FERMOs e de Σ(FERMO) ci2 em conjunto com baixos valores de eletrofilicidades e cargas extremamente negativas no átomo N1 são parâmetros relevantes para potencializar as afinidades ligantes de outros compostos a serem sintetizados, que apresentem estruturas químicas semelhantes às moléculas estudadas neste trabalho. Além disso, esses compostos podem ser considerados como doadores de elétrons e, logo, há uma grande probabilidade que tais moléculas interajam com o receptor histamínico H3 a partir de um processo de transferência de carga. / In this thesis, molecular orbital calculations were carried out on a set of 28 non-imidazole H3 antihistamine compounds using Austin Moldel 1, Hartree-Fock-Roothaan, and Density Functional Theory methods in order to investigate the possible relationships between electronic descriptors and binding affinity for H3 receptors (pKi). It was observed that the frontier effective-for-reaction molecular orbital (FERMO) energies were better correlated with pKi values than HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) energy values. Exploratory data analysis through hierarchical cluster (HCA) and principal component analysis (PCA) showed a separation of the compounds into two sets by using four descriptors, one grouping the molecules with high pKi values, the other gathering low pKi value compounds. This separation was obtained with the use of the following descriptors: FERMO energies (εFERMO), charges derived from the electrostatic potential on the nitrogen atom (N1), electronic density indexes for FERMO on the N1 atom (Σ(FERMO) ci2), and electrophilicity (ω\'). These electronic descriptors were used to construct three quantitative structure-activity relationship (QSAR) models through the Partial Least Squares Method (PLS). The best model generated Q2 = 0.88 and R2 = 0.927 values obtained from a training set and external validation of 23 and 5 molecules, respectively. After the analysis of the PLS regression equation, the values for the selected electronic descriptors and other descriptors, it is suggested that high values of FERMO energies and of Σ(FERMO) ci2, together with low values of electrophilicity and pronounced negative charges on N1 appear as desirable properties for the conception of new molecules which might have high binding affinity. Moreover, these molecules can be classified as electron donating compounds and have a great probability of interacting through a charge transfer process with the biological receptor H3.
9

Dry and wet atmospheric deposition of polycyclic aromatic hydrocarbons at a Kaohsiung coastal site.

Chen, Kuan-Wei 26 December 2011 (has links)
Polycyclic aromatic hydrocarbons (PAHs) are one of major classes of organic pollutants. As semi-volatile organic compounds, PAHs can be transported in the atmosphere and scavenged according to various processes (dry and wet deposition). Atmospheric deposition is an important pathway for the transfer of pollutants from atmosphere to the terrestrial and water surfaces. The objective of this research is to quantify the dry and wet deposition of the atmospheric PAHs in the Kaohsiung coastal area. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were also performed with diagnostic ratios to determine the potential sources of PAHs. The mean dry and wet deposition fluxes of atmospheric total suspended particles (TSP) during the study period (January-December 2010) were estimated to be 44.3 (6.60-384) and 211 (56.1-738) mg/m2d, respectively. The annual mean total PAH fluxes in dry and wet deposition were 1500 (749-3760) and 8470 (2280-46000) ng/m2d, respectively. Both concentrations and dry deposition fluxes of TSP were much higher during dust storm. During Ghost Month, however, they were comparable with other sampling events. By comparing with literatures, the total PAH concentrations of TSP were relatively low during Ghost Month, suggesting that wind direction and precipitation might be plausible. The ratio of PM2.5/PM10 had a relatively low value during dust storm, indicating that coarse particle might be predominant. In addition, during dust storm, both TSP dry deposition velocity and total PAH dry deposition velocity were higher than other sampling events. Our findings in this study showed that previous attempts in literature to estimate total PAH dry deposition fluxes by using TSP dry deposition velocity and PAH concentrations could lead to overestimate fluxes in the field. TSP dry deposition fluxes were positively correlated with atmospheric total TSP concentrations and TSP dry deposition velocity, but were correlated negatively with intensity of precipitation. In addition, TSP dry deposition velocity showed a positive correlation with TSP concentrations. Total PAH dry deposition fluxes were correlated positively with atmospheric total particulate concentrations and total PAH dry deposition velocity, but negatively with intensity of precipitation and temperature. However, TSP and total PAH fluxes in wet deposition were both correlated positively with intensity of precipitation. Diagnostic ratios showed that diesel exhaust was the main source of combustion-derived PAHs in the study. HCA and PCA analysis indicated that emissions from the ships and vehicles, and fuel used were the main sources of combustion-derived PAHs, while during special events, such as dust storm and Ghost Month, suggesting a different source of PAHs.
10

The distribution of the Polycyclic Aromatic Hydrocarbons in the Love River and Chianjen River

Lee, Yu-hui 10 August 2005 (has links)
Turning back to look Kaohsiung city¡¦s development and history of exploitation, both of them had a close relationship with the Love River and Chianjen River. Along the rivers, there are numerous industrial estates and large population. The basin of the rivers is important in politics and economy to Kaohsiung. However, the development of Kaohsiung also causes organic pollution, such as polycyclic aromatic hydrocarbon (PAHs), released to water system. Furthermore, some of these pollutants are carcinogenic, so that this topic is quite important. This study investigates PAHs concentrations and seasonal variations in sediments and suspended solids of these two rivers. Total PAHs concentrations varied from 110 to 4300(ng g-1 dry wt) in sediments and 1500 to 7000(ng g-1 dry wt) in suspended solids of the Love River. Total PAHs concentrations of sediments and suspended solids of the Chianjen River exhibited in the range of 230-3900 (ng g-1 dry wt) and 490-9200 (ng g-1 dry wt), respectively. The average PAHs concentration during rain/ dry season of the Chianjen River is significantly higher than those of the Love River. Compared with global data in literature, level of total PAHs concentrations in sediments and suspended solids of the Love River and Chianjen River belongs to moderate pollution. Total PAHs and total organic carbon (TOC) is significantly related except suspended solids of the Chianjen River. However, the relationship between total PAHs concentrations and mean particle size is not significant because of inequilibrium resulted from different sources. Referring to Sediment quality guidelines (SQGs), most of stations are in safe range, only total PAHs concentrations at station L8 in rainy season is significantly higher than the standard ERL value. For each individual compound, the concentrations of many low-molecular-weight PAHs are higher than their standard ERL¡BLET and LAET values. The result of HCA shows that in both dry and rain season, these two rivers¡¦ sediments and suspended solids are separated into upstream and downstream groups. It is believed that the existence of an intercept device set up in midstream of both rivers is the reason. The PAHs in sediments of the Love River is mainly contributed from automobile exhaustion, while suspended solids in the Love River is mainly contributed from petrogenic source. However, both sediments and suspended solids in the Chianjen River are mainly contributed from combustion pollution.

Page generated in 0.0395 seconds