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  • 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.
661

Spatial and Temporal Characteristics of Volatile Organic Compounds and Ozone Formation Potential in Industrial Park

Lin, Jia-shiang 23 June 2011 (has links)
This study measured Ambient concentrations of air pollutants and Volatile Organic Compounds (VOCs) in industrial park in Kaohsiung City. The spatial distribution was investigated during different time periods and seasons. The ozone formation potential (OFP) of VOCs species were evaluated based on the maximum incremental reactivity (MIR). Also, this study using factor analysis to estimate the polluted source. The season distribution of air pollutants showed concentration in spring higher than summer, owing to air activities of summer are acute include wet precipitation, photochemical reaction, and convection. The time period distribution showed the results which NOx and O3 concentration occurred peaks at 7:00 − 8:00, 18:00 − 19:00 and 13:00 − 16:00, respectively. The reason is photochemical reaction, lead to concentration trend with time of NOx inversely to O3. The concentration trend with time of CO and PM10 similar to NOx. The polluted sources were estimated mobile. By the way, O3 is proportional to temperature, but it is Inversely proportional to humility. The seasons distribution of VOCs showed most abundant species included 2-butanone, toluene, and n-pentane in spring, while included toluene, acetone, m,p-xylene, and methyl methacrylate in summer. According to percent composition, most abundant categories in spring and summer were both aromatics, ketones, and alkanes. The TVOC concentration was spring (164.6 £gg/m3) higher than summer (116.4 £gg/m3). The time periods distribution of VOCs showed most abundant categories included aromatics and ketones in morning and evening, while included aromatics and alkanes in night. The TVOC concentration of evening (163.2 ¡Ó 62.7 £gg/m3) was highest, followed by night (159.9 ¡Ó 87.4 £gg/m3), Lowest was morning (98.4 ¡Ó 32.3 £gg/m3). Results showed alkanes and alkenes own higher concentration in night, ketones and esters in evening, and aromatics in evening and night. The reason is related with sunshine, inversion layer, and lower wind speed. By the way, TVOC is proportional to temperature. In spring, the OFP was 566.0 £gg-O3/m3, OFP/TVOC was 3.44. In summer the OFP was 629.3 £gg-O3/m3, OFP/TVOC was 5.41. It was worth mentioning highest OFP categories in spring and summer was both aromatics (332.2 £gg-O3/m3, 380.3 £gg-O3/m3), and highest OFP species was toluene (138.8 £gg-O3/m3) and methyl methacrylate (171.7 £gg-O3/m3) , respectively. The results from factor analyses showed the predominant source included mobile polluted source, petrol evaporation, related electronic industry, metallurgy industry, refinery, and architectural coatings escape in spring. The predominant source included mobile polluted source, petrol evaporation, plastic industry, steel industry, and related electronic industry in summer.
662

Develop Microchip with Gold Nanoelectrode Ensemble Electrodes for Electrochemical Detection of Verapamil

Chuang, Jui-Fen 11 August 2011 (has links)
Verapamil is a commonly used medicine for the treatment of supraventricular arrhythmias, angina and hypertension. Recently, some newly developed applications of Verapamil, such as treating hypomania and chemotherapy for cancers, have been reported. Thus, monitoring the concentration of Verapamil accurately is very important. The major clinical analytical methods of Verapamil concentration determination are high performance liquid chromatography (HPLC) with UV or with fluorescence detector. However, these analytical methods have some disadvantages, like expensive instruments, complex operation, and time-consuming etc. The chemical structure and properties of Verapamil are very stable. The preliminary result of electrochemical analysis doesn¡¦t show any electrochemical activity. In this study, we developed an innovative ozone pre-treatment method to oxidize Verapamil to the smaller molecules and change its structure. Verapamil have excellent electrochemical activity after ozone pre-treatment. The spectroscopy and mass spectrometry show the changes of Verapamil structure. The products of Verapamil treated with ozone are also predicted by mass spectrometry. The gold nanoelectrode ensemble electrodes (GNEE) are used as working electrode for its good catalytic activity of electrochemical reaction, high sensitivity and high selectivity. The overall experimental framework of this study is microchip with GNEE working electrode accompanied by cyclic voltammetry, an electrochemical analytical instrument. Compared with traditional analytical methods, the system has some advantages such as small size, micro sample volume, easy operation, rapid detection and low cost. The limit concentration of Verapamil solution for stable detection in the system is 10 ng/mL. A linear dynamic range with a high correlation factor from 10 ng/mL to 100 £gg/mL was obtained. For the analysis of serum sample, Verapamil present excellent electrochemical activity at 1 ng/mL. A linear dynamic range with a high correlation factor from 1 ng/mL to 100 £gg/mLwas obtained. According to the results, our system for clinical Verapmil concentration analysis has the feasibility of the practical application.
663

Vertical Distribution and Seasonal Variation of Volatile Organic Compounds in the Ambient Atmosphere of a Petrochemical Industrial Complex

Yang, Jhih-Jhe 02 September 2011 (has links)
The emission of volatile organic compounds (VOCs) and odors from petrochemical industrial complex, including China Petroleum company (CPC),Renwu and Dazher petrochemical industrial parks, causes poor air quality of northern Kaohsiung. The removal efficiencies of elevated stacks and flares might play important roles on ambient air quality in metro Kaohsiung. Consequently, this study applied a tethered balloon technology to measure the vertical profile of VOCs, and ascertained their three dimensional dispersion in the atmosphere. The vertical profile of VOCs in ambient atmosphere surrounding the petrochemical industrial complex was measured during the intensive sampling periods (September 17-18th and December 20-21st, 2009 and April 8-9th and July 7-8th, 2010). Moreover, this study was designed to sample and analyze VOCs emitted from elevated stacks and flares, and estimate their emission factors. Finally, the source identification and ozone formation were further determined by principal component analysis (PCA) and ozone formation potential (OFP). This study found that some regions had relatively poorer air quality than other regions surrounding the petrochemical industrial complex. Most sampling sites with poor air quality were located at the downwind region of the petrochemical industrial complex, particularly with the prevailing winds blown from the northwest. Moreover, stratification phenomena were frequently observed at most sampling sites, indicating that high-altitude VOCs pollution should be considered for ambient air quality. This study revealed that the indicators of VOCs in northern Kaohsiung were toluene, C2 (ethylene+acetylene+ethane), and acetone. Vertical sampling of VOCs showed that the species of VOCs at the ground and high altitude were different, suggesting that ambient air quality at high altitude might be affected by the emission of VOCs from elevated stacks and flares at the petrochemical industrial complex. Results obtained from PCA showed that the major sources of VOCs in the ambient atmosphere of the petrochemical industrial complex were similar to the characteristics of VOCs emitted from the petrochemical industrial complex. The characteristics of VOCs at high altitude had strong correlation with petrochemical industry, indicating that the ambient air quality of northern Kaohsiung was highly influenced by the emission of VOCs from high stacks and flares. In addition, major VOCs for O3 formation potential at northern Kaohsiung were aromatics and vinyls, with particular species of toluene and C2. Moreover, air pollution episodes resulting from high O3 concentration was usually observed in early winter. Flare sampling results indicated that major VOCs emitted from the ground flare of CPC were alkanes and vinyls. The average removal efficiency of TVOCs was 98.2%. The average emission factor of VOCs was 0.0186 kg NMHC/kg flare gas. In addition, stack sampling results indicated that the emission factors of crude oil distillation process (P105), mixing process (P060), and rubber manufacturing process (P408) were 0.105, 1.11, and 61.97 g/Kl, respectively. The emission factor of P105 was lower than AP-42, while that of P408 was higher than AP-42.
664

Treatment of Volatile Organic Compounds in Cooking Oil Fume Emitted from Restaurants by Nano-sized TiO2 Photocatalyst Coated Fiberglass Filter and Ozone Oxidation Technology

Lai, Tzu-Fan 20 August 2012 (has links)
Recently, restaurant employees exposing to cooking oil fume with potential lung cancer was highly concerned, indicating cooking oil fume emitted from restaurants might cause tremendous hazard to human health. This study combined photocatalytic oxidation and ozone oxidation technology to decompose VOCs from the exhaust of cooking oil fume from restaurants. Firstly, this study selected three different types of restaurants to implement air pollutant measurements in the indoor dinning room and stack emission. Indoor TVOCs continuous monitoring data showed that the highest TVOCs concentration was generally observed in the dining peak time. In this study, photocatalyst coated fiberglass filter was prepared by impregnation procedure and its characteristics was analyzed by SEM and XRD. Experimental results showed that the particle size of photocatalyst ranged from 25 to 50 nm and had high percentage of Anatase, suggesting that it had high photocatalytic reactivity. This study designed a continuous-flow reaction system combined nano-sized TiO2 photocatalysis with ozone oxidation technology to decompose VOCs from cooking oil fume. After passing through a fiberglass filter to remove oil droplets, the cooking oil fume then coated with nano-sized titanium oxide (UV/TiO2) fiberglass filter purification system, and then injected ozone into the system to decompose residual VOCs. This study further investigated the influences of operating parameters, including TVOCs initial concentration, O3 injection concentration, and reaction temperature on the decomposition efficiency of TVOCs by using the UV/TiO2/O3 technology. When the photocatalytic reaction temperature was 35~50¢J, the TVOC decomposition efficiency slightly increased with reaction temperature, however, when the reaction temperature went up to 55¢J, the TVOC decomposition efficiency increased only slightly, but did not increased linearly. Combination of photocatalysis and ozone oxidation system performance test results showed that ozone could decompose approximately 34% VOCs, and followed by the photocatalytical reaction of residual pollutants, achieving an overall decomposition efficiency of about 75%; while photocatalytic reaction can remove 64% of TVOCs and followed by O3 for the decomposition of residual pollutants, achieving an overall decomposition efficiency up to 94%. It showed that the combined UV/TiO2+O3 system could effectively remove VOCs in the cooking oil fume from the exhaust of restaurants. By using GC/MS to qualitatively analyze the speciation of TVOCs from cooking oil fume before and after UV/TiO2/O3, the results showed that the composition of VOCs had a decreasing trend. The peak area and dilution factor were applied to estimate the decomposition efficiency of different VOCs species. The decomposition efficiencies of pentane, 2-acrolein, acrolein, heptane, pentanal, hexanal, 2-hexenal, heptanal, heptenal and ethylhexenal were 56.21%, 72.88%, 51.33%, 32.23%, 59.04%, 69.22%, 73.53%, 41.37%, 92.57%, and 96.02%. Finally, a Langmuir-Hinshelwood kinetic model was applied to simulate the photocatalytic decomposition efficiency with the initial concentration of cooking oil fume. Model simulation results showed that the reaction rate increased with the initial TVOCs concentration. However, when TVOCs concentration increased gradually, the reaction rate became constant since the activated sites on the photocatalyst¡¦s surface was limited and cannot allow more VOC molecules diffuse to the activated sites for further photocatalytic reaction.
665

Spatial and temporal characteristics of C2-C15 hydrocarbons and receptor modeling in the air of urban Kaohsiung, Taiwan

Lai, Chia-hsiang 16 June 2004 (has links)
The concentrations of seventy-one hydrocarbons (HC) from C2 to C15 were measured simultaneously at two sites in Kaohsiung city in the morning (07-10), the afternoon (13-16), and the evening (18-21) on 14 days in spring 2003. Results show that the most abundant species of Kaohsiung¡¦s air is toluene (43.36-54.49 £gg m-3), followed by i-pentane, 1,2,4-trimethylbenzene, benzene, n-butane, propane and acetylene, in the range 10.36¡V17.11 £gg m-3. The concentrations of 14 halocarbons are in the range 0.25¡V4.57 £gg m-3. Alkanes (around 44.8%) represent the largest proportion of the total HC, followed by aromatics (35.1%), alkenes (15.5%) and halocarbons (5.4%). The afternoon HC concentrations are much lower than those in the morning and at night, due to relatively intense photochemical reaction and favorable dispersion conditions from noon to afternoon. Notable increases in daily HC concentrations are consistent with high temperature, and low HC concentrations on Sunday coincide with low traffic volume. Photochemical activity is investigated, and HC concentrations are found to decline as the NO2/NOx ratio increases. Correlation analyses imply that vehicle exhaust is the dominant source of atmospheric hydrocarbons in Kaohsiung. The profiles of traffic exhausts were also measured for 25 HC species during the morning and afternoon rush hours on four different days in all three traffic tunnels in Kaohsiung City. Results show that VOC concentrations increase with traffic flow rate, and emission profiles in the three tunnels are mostly in the range C2 ¡V C6. Besides the traffic conditions and vehicle type, the pattern of emissions in each tunnel was also influenced by other factors, such as vehicle age, nearby pollution sources, and the spatial or temporal variation of HC in the urban atmosphere. The ozone formation potential (OFP) in each tunnel was assessed based on the maximum incremental reactivities of the organic species, demonstrating that OFP increases with traffic flow rate. Vehicle distribution influences the contributions of organic group to OFP in a tunnel. Meanwhile, when ranked in descending order of contribution to OFP in all tunnels, the organic groups followed the sequence alkenes, aromatics, and alkanes. The possible source categories affecting the atmospheric HC species were further analyzed using factor analysis. Results showed that the major sources of ambient HC at the Nan-Chie and Hsiung-Kong sites are: vehicle exhaust, petrol/diesel exhaust, industrial processes (for example, plastic/rubber process), combustion exhaust, solvent fugitive or business/consume exhaust. Based on the results of factor analysis, source profiles (or fingerprints) were selected and receptor modeling was conducted based on chemical mass balance (CMB). Results of receptor modeling indicated that, at Nan-Chie site, vehicle exhaust (46.33% and 56.36%) represent the largest proportion of total HC, followed by industrial processes (29.63% and 22.37%) in the morning (07-10) and the evening (18-21), respectively; but were industrial process (40.39%) and solvent fugitive exhaust (30.61%) in the afternoon (13-16). Similarly at Hsiung-Kong site, vehicle exhaust (around 46.19% and 49.29%) represent the largest proportion of total HC, followed by industrial processes (23.19% and 26.11%) in the morning and evening, respectively; but were solvent fugitive exhaust (38.85%), vehicle exhaust (28.95%) and industrial process (25.19%) in the afternoon. It is evident that relatively low traffic volumes in the afternoon at both sites reduce the contribution of traffic exhaust to ambient HC.
666

Free radical mediated cellulose degradation

Johansson, Erik January 2003 (has links)
<p>This thesis addresses the mechanisms involved in cellulosedegradation in general and Totally Chlorine Free (TCF) bleachingof pulp in particular. The thesis shows that the cellulosedegradation during high consistency ozone bleaching is explainedby free radical chain reactions.</p><p>By simulation, it has been shown that the number, weight andviscosity average of liner polymer chain length can be used tocalculate the number of random scissions in a linear polymer ofany molecular weight distribution, provided that there is acalibrated Mark-Houwink equation. A model describing partialdegradation of molecular weight distributions of linear polymersmeasured with viscometry was developed and verifiedexperimentally. The model predicts viscometric measurement ofchemical cellulose degradation by a rapidly reacting reagent tobe strongly dependent on cellulose accessibility.</p><p>The role of free radical reactions in cellulose degradationwas studied by varying the amount of ferrous ions and ozone addedto the cotton linters. The result was compared to the resultsobtained from cellulose of lower crystallinity (cellulose beads)by measuring average chain length. When a ferryl ion reacted withcotton linters in the presence of ozone, the very formation ofone glycosidic radical was more significant to degradation thanthe final step of forming one oxidised glycoside. The inefficientdegradation observed of the oxidation step is explainable by theamount of accessible glycosides being too small to influenceviscometry. The efficient degradation observed in associationwith the glycosidic radical formation is explained by initiationof free radical chain reactions that are propagated as long asthere is ozone in the system. As none of these phenomena werefound in the less crystalline cellulose, cellulose structureappears to be important for how free radical mediated cellulosedegradation develops.</p><p>The theory of free radical chain reactions coupled withdiffusion suggests a concentric expansion of the chain reactionsoutwards from the initial site of radical formation duringozonation of carbohydrates. This was confirmed by demonstratingfree radical chain reactions spreading from a spot of initiationoutwards during ozonation of a filter paper, using a pH-indicatorto monitor acid formation. Furthermore, the interior and exteriorof cellulose fibres doped with initiator were shown to bepermeated by small holes after ozonation.</p><p>Ethylene glycol was shown to improve the selectivity duringozone bleaching of oxygen bleached kraft pulp at pH 3. Optimalconditions were obtained at pH 3 for 25 wt% ethylene glycol. Theinfluence of ethylene glycol on selectivity is explained by aproportion of the free radical chain reactions being carried bythe ethylene glycol instead of the cellulose during ozonebleaching. The observations were summarised in the form of amodel where the observed degradations for pulp, bleached pulp andcotton fibres during both ozone bleaching and ethylene glycolassisted ozone bleaching were shown to agree with each other.</p><p>From g-irradiation of ozonised aqueous solutions of alcohol,the rate constant of superoxide formation from the peroxylradical of methanol was estimated to be 10 s<sup>-1</sup>. Rate constants of the reactions between ozone andalkylperoxyl radicals were determined to be around 10<sup>4</sup>M<sup>-1</sup>s<sup>-1</sup>. The possibility of the reaction betweenalkylperoxyl radicals and ozone contributing significantly tofree radical chain reactions during ozonation of carbohydratesand alcohols could therefore be ruled out.</p><p>Cellulose, degradation, free radical, ozone, selectivity,ethylene glycol, alcohol, bleaching, kraft pulp, cotton linters,delignification, fibre, fibril, crystallinity, ferryl ion, freeradical chain reactions, TCF, viscometry, molecular weightdistributions, random scissions.</p>
667

Développement du service d'observation PAES : pollution atmosphérique à l'échelle synoptique, bilan de l'ozone dans la troposphère libre

Chevalier, Amandine 24 October 2007 (has links) (PDF)
La thèse s'est inscrite dans le développement du service d'observation PAES (Pollution Atmosphérique à l'Échelle Synoptique), réseau de stations d'altitude, dédié à la mesure à long terme de l'ozone et de ses principaux précurseurs gazeux. La représentativité spatiale et temporelle a été évaluée grâce à l'analyse des données de surface comparées à des mesures aéroportées (MOZAIC) et satellitaires (MOPITT) ; les stations d'altitude s'avèrent capables de suivre les changements globaux de la composition de l'atmosphère et, dans une certaine mesure, sont représentatives de la variabilité de la troposphère libre malgré l'influence de la surface. Un bilan de la qualité de l'air en Europe de l'Ouest, depuis les années 1990 a été dressé à partir des données d'ozone et de CO de PAES et de différents réseaux français et européens. Enfin, l'analyse couplée des données d'observation obtenues pendant la campagne de terrain PIC 2005 (13 juin - 7 juillet 2005 autour du Pic du Midi) et de simulations (Méso-NH) a permis notamment de comprendre le cycle diurne inversé de l'ozone observé dans des climatologies issues de certaines stations d'altitude. Le rôle du transport à l'échelle synoptique et des échanges entre couche limite et troposphère libre sur la mesure en altitude a été montrée dans l'étude détaillée de l'épisode de pollution du 23 juin 2005.
668

Ozone et qualité de l'air intérieur : interactions avec les produits de construction et de décoration

Nicolas, Mélanie 12 October 2006 (has links) (PDF)
L'impact de l'ozone sur la qualité de l'air intérieur a été étudié par une double approche permettant d'une part, de mieux comprendre les mécanismes réactionnels de disparition de l'ozone au contact des surfaces intérieures et d'identifier les produits de réactions, et d'autre part, d'étudier le transfert de l'ozone depuis l'extérieur vers l'intérieur et son comportement in situ, notamment en période de pics de pollution photochimique.<br />Un banc d'exposition contrôlée a été mis au point pour étudier les interactions entre l'ozone et seize produits de construction et de décoration fréquemment rencontrés dans les environnements intérieurs. Pour tous les matériaux testés, une disparition d'ozone significative, comprise entre 8% pour une peinture glycérophtalique et 89% pour un lambris en pin brut, a été observée. Des vitesses apparentes de dépôt de l'ozone sur les matériaux variant de 0,003 à 0,158 cm•s-1 ont été calculées. Les émissions des matériaux sont modifiées en présence d'ozone. Certains composés sont détectés en concentrations inférieures (styrène, alcènes C12) tandis que d'autres sont retrouvés en concentrations nettement supérieures, notamment des aldéhydes (formaldéhyde, acétaldéhyde, benzaldéhyde, C5 à C10), des cétones et des acides carboxyliques. Lors d'essais conduits sur un lambris en pin, la prédominance des mécanismes hétérogènes dans la disparition d'ozone a été mise en évidence, la contribution des réactions en phase homogène étant estimée entre 5 et 20 %.<br />L'impact de la pollution photochimique sur la qualité de l'air intérieur a été étudié durant les étés 2003 et 2004 dans la maison expérimentale MARIA du CSTB. Il apparaît que la pollution extérieure (NO, NO2 et O3) est complètement transférée dans la pièce par le système de ventilation. Près de 80% à 95% de l'ozone est éliminé à l'intérieur de la pièce, témoignant ainsi de la présence d'importants puits d'ozone. Des sous-produits réactionnels ont été identifiés, en particulier le formaldéhyde, l'hexaldéhyde, le benzaldéhyde et le nonanal. Il apparaît que la réactivité en phase hétérogène prédomine sur les réactions en phase gazeuse, bien que des réactions d'ozonolyse d'alpha-pinène aient été observées dans la pièce. Les variations quotidiennes des concentrations intérieures de l'ozone et de certains composés (formaldéhyde, hexaldéhyde) soulignent le rôle de la réactivité chimique et des paramètres environnementaux (surtout la température) sur les émissions de certains matériaux, et donc sur leurs concentrations dans l'air intérieur.<br />Un modèle simple de prédiction des concentrations intérieures de polluants a été mis au point. Les prévisions sont réalisées d'après les concentrations extérieures des polluants et intègrent la réactivité en phase homogène et en phase hétérogène. Pour NO, les données simulées et réelles sont quasiment identiques tandis que le modèle surestime les concentrations intérieures de NO2, probablement du fait de l'absence de prise en compte du dépôt de NO2 sur les surfaces intérieures. Les prévisions des concentrations intérieures d'ozone sont très satisfaisantes.
669

Caractérisation de la tropopause extratropicale avec les données aéroportées<br />MOZAIC : zone de mélange et d'échange

Brioude, Jérôme 26 September 2006 (has links) (PDF)
Cette thèse porte sur l'analyse des données MOZAIC pour améliorer la connaissance<br />des ´échanges stratosphère-troposphère (STE) au niveau du cas d'étude ou au niveau global saisonnier. L'utilisation de techniques lagrangiennes et du modèle meso-échelle MESO-NHmet en évidence l'importance des STE sur la distribution chimique de l'UTLS dans un casde cyclogenèse d'été. Une ´étude lagrangienne d'un second cas d'étude montre que les zonesfrontales des moyennes latitudes peuvent être responsables d'une stratification en couchesde masses d'air issues de différents courants cohérents. Enfin, l'impact des STE sur lesdistributions saisonnières d'ozone et du CO aux moyennes latitudes dans la zone UTLS estprésente. Un nouveau repère dynamique permet un replacement cohérent des observationsle long des dorsales et des thalwegs d'altitude. La formation d'une couche de mélange audessus de la tropopause, et les variations chimiques saisonnières sont présentées. Une analyse lagrangienne des variations zonales est tentée.
670

Pollution atmosphérique par l'ozone et asthme de l'enfant résultats de l'étude Airpole (asthme infantile et retentissement de la pollution de l'environnement) /

Godard, Sophie. Zmirou-Navier, Denis. January 2004 (has links) (PDF)
Reproduction de : Thèse d'exercice : Médecine : Nancy 1 : 2004. / Titre provenant de l'écran-titre.

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