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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.
1

Effect of secondary metabolites on gall fly infestation of mango leaves

Augustyn, WA, Maree, JE, du Plooy, GW, Botha, BM, Combrinck, S 15 June 2010 (has links)
Abstract Themango gall fly (Procontarinia) is a growing concern in many countries that importmango trees.Mangoes flush (produce opening buds) twice a year: once in spring, and the main flush, which occurs in early autumn flush and corresponds to the photoperiod necessary for the gall fly to emerge. Gall flies attack only very young mango flush leaves. Three cultivars displaying varying susceptibility were used in this study: Heidi, which typically is heavily infected; Keitt, which displays antixenosis properties; and Sensation, which is resistant to gall fly attack. Headspace profiles of the three cultivars were obtained over two full growing seasons. It was found that flush leaves emit higher levels of volatile organic compounds than mature leaves. Volatile emissions peaked during the main flush, after which they declined as the tree went into the winter dormant period. The levels of a- and b-pinene increased in gall fly-susceptible cultivars as the season progressed, while very low levels of these terpenes were emitted by resistant cultivars. The changes in the profiles of these emissions suggest that aand b-pinene may be linked to gall fly susceptibility. In addition, chemometric analysis confirmed the correlation between volatile emissions and gall fly susceptibility.
2

Correlation of volatile profiles of twenty mango cultivars with their susceptibilities to mango gall fly infestation

Augustyn, WA, Botha, BM, Combrinck , S, Du Plooy, SW 27 October 2010 (has links)
Abstract Mango gall fly (Procontarinia matteiana) is an orchard pest that parasitises flush leaves of mango and serious outbreaks may result in reduced fruit yield. The trigger for infestation is unknown, but terpenes emitted by the leaves appear to play a role in attraction. Metabolic profiles of three mango cultivars of varying susceptibility to mango gall fly attack were obtained by headspace profiling using GC-FID and GC-MS analysis. Chemometric models constructed from the data revealed that three terpenes, α- and β-pinene and camphene could be useful as biomarkers for susceptibility. Headspace profiles of twenty other cultivars, naturally exposed to gall fly, were obtained in the same way. Susceptibility or resistance of these cultivars was predicted using the developed orthogonal partial least squares model. Predictive outcomes were thereafter verified by visual examination of the leaves to detect gall formation, an indication of gall fly infestation. The model was found to predict the susceptibility or resistance of 90% of the cultivars accurately. This finding indicates the contributory role of the three terpene biomarkers in mango gall fly interaction and may direct future studies to determine their inter-relationship.
3

Produção de Precursores para a Preparação do NiTiO3: Síntese e Caracterização Utilizando as Técnicas Integradas TG, DSC, FTIR, ICP-OES, CHN e DRX.

MURI, E. J. B. 22 February 2013 (has links)
Made available in DSpace on 2016-08-29T15:35:31Z (GMT). No. of bitstreams: 1 tese_6362_Emanuele José Bassani Muri20140909-104234.pdf: 2713829 bytes, checksum: 68a4cd619df483912c21049eb8ab9133 (MD5) Previous issue date: 2013-02-22 / A proposta deste trabalho foi estudar e caracterizar os produtos gerados na reação entre o acetato de níquel hidratado (NiAc2.4H2O) com o isopropóxido de titânio (Ti(OiPr)4) em meio reacional contendo o tetrahidrofurano (THF) combinado com o desidratante trietilortoformiato de etila (TOFE). A mistura de reação foi deixada sob agitação constante em diferentes tempos reacionais (0,5; 1,0; 2,0; 24; 48 e 72 h). Os sólidos obtidos foram isolados por decantação do sobrenadante, e em seguida foram lavados com hexano e secos sob pressão reduzida gerando, respectivamente, os compostos A, B, C, D, E e F. Esses compostos foram decompostos termicamente e os produtos gerados foram caracterizados visando encontrar a melhor rota de síntese do titanato de níquel (NiTiO3), tendo-se em conta a relação da hidrólise do Ti(OiPr)4 em função do tempo reacional. Os compostos A, B, C, D, E e F e seus derivados após o tratamento térmico foram caracterizados por técnicas de espectroscopia de absorção na região do infravermelho com transformada de Fourier (FTIR), análise elementar de Ni, Ti e CHN, difratometria de raios X pelo método do pó (DRX), análise térmica (TG / DTG / DSC) e ensaio de Headspace. Os resultados destes ensaios de caracterização dos compostos A, B, C, D, E e F permitem observar que bandas de absorção do grupo Ti-O-C na região do infravermelho aparecem apenas nos compostos obtidos com tempo reacional menor que 2 horas devido este tempo ser inferior ao necessário para a ocorrência total da hidrólise do alcóxido Ti(OiPr)4. O resultado do ensaio de Headspace monstrou que no aquecimento do composto B, a 100 ºC, ocorre a geração de voláteis formados por uma fração de etanol e isopropanol. Os ensaios TG/DTG (em atmosfera dinâmica de ar sintético e N2) dos compostos evidenciam que a primeira perda de massa ocorre abaixo de 100 ºC permitindo concluir que a reação de hidrólise ainda não havia se completado, devido à liberação destes subprodutos gerados após o aquecimento. Segundo os resultados de DRX, os compostos produzidos abaixo de 2h, após tratados termicamente, geram como produto o NiTiO3, uma pequena fração de TiO2 na fase rutilo e NiO. Para os demais compostos, a fase NiO desaparece. Desta forma, os resultados evidenciam a formação do NiTiO3 em todos os tempos reacionais, indicando que o objetivo deste trabalho foi atingido. Entretanto, observa-se a necessidade de um maior refinamento do método, uma vez que o NiTiO3 não foi obtido em fase única.
4

Estudo da correlação instrumental e sensorial de uma composição aromática aplicada na pele em função do ciclo menstrual / Study of instrumental and sensory correlation of a aromatic composition on the skin in function of mentrual cycle.

Costa, Claudia Silva Cortez Pereira da 19 December 2013 (has links)
A área de perfumaria no mundo vem se desenvolvendo a cada dia buscando maior conhecimento das matérias-primas aromáticas, desde suas reações, estabilidade até suas interações com o substrato onde é aplicado, sempre em busca do conhecimento de todas as variáveis que possam influenciar a relação perfume-substrato e a aceitação dos consumidores, medida por meio da avaliação sensorial. Apesar de muitos estudos sobre a relação perfume-pele, poucos envolveram a relação com ciclo menstrual. Neste estudo o objetivo foi correlacionar às análises sensorial e instrumental (medidas biomecânicas e cromatográficas), estudar as matérias-primas aromáticas em função do ciclo menstrual. O estudo envolveu indivíduos com idade entre 18-40 anos: 29 mulheres e 3 homens, estes usados como grupo controle. Cada voluntária teve 40 &#181;l da composição aromática Ciclo 1910 aplicado no antebraço, onde foram feitas as medidas biomecânicas (corneometria, sebumetria e TEWL) nos tempos inicial e 6h. Nos tempos inicial, 1.5h, 3h, 4,5h e 6h se auto-avaliaram sensorialmente a intensidade de perfume por meio de escala sensorial de magnitude rotulada (LMS) e foram coletados os compostos aromáticos liberados pela técnica de headspace e analisados por espectrometria com cromatografia a gás e detetor de massa (CGMS). Realizou-se também medidas biomecânicas de corneometria, sebumetria e TEWL interescapulares em 5 voluntárias nos tempos inicial e 6h para comparação. Os resultados obtidos foram que as fases do ciclo não interferiram nas variáveis biomecânicas (p>0,05) quando analisadas isoladamente. Para as medidas realizadas no antebraço, os índices de Corneometria (p<0,001) e TEWL (p: 0,011) na região tratada apresentou média maior que a do controle. A média dos índices de Corneometria e Sebumetria da região do antebraço tratada foi menor (p<0,001) que da região interescapular. Na análise cromatográfica não houve um padrão de resposta em diferentes fases do ciclo. As correlações entre a avaliação sensorial e instrumental (cromatografia e propriedades biomecânicas) não observaram nenhum nível de correlação (p>0,05). A Cromatografia (dados cromatográficos) foi maior na fase Folicular que nas fases Menstrual e Ovulatória (p=0,003), ao considerar como variável resposta em função do ciclo menstrual e da avaliação sensorial. Houve uma forte correlação positiva entre a análise sensorial e a avaliação na pele do homem (p<0,001). No entanto, o fator intrínseco do indivíduo Mulher influenciou na resposta, ocasionando grande variabilidade, porém percebeu-se claramente que os hormônios sexuais interferiram na resposta sensorial, cromatográfica e biomecânica da pele. / The perfumery in the world has been developed everyday bringing more knowledge about aromatic raw-materials, as from chemistry reactions, stability until their interactions with substrate where is applied, always looking for variables could influence in the relation perfume-substrate and consumer acceptability, measured by sensory evaluation. Despite a lot of studies were done on this subject, few involved effects as function of menstrual cycle. The aim of this study was to correlate sensory and instrumental analysis (biomechanical and chromatographic measurements), to study the olfactory profile of raw materials in function of menstrual cycle. The study involved people with 18-40 years old: 29 volunteers, three men, who were used as control group. Each volunteer had 40 &#181;l of perfume applied on forearm, where were done Biomechanical measurements (Corneometer, Sebumeter and TEWL) at initial and 6h, At time initial, 1.5h, 3h, 4.5h and 6h; they did self-sensory assessment in perfume intensity in own forearm using labeled magnitude scale (LMS) and also where aromatic compounds released were collected by headspace technique spectrometry and gas chromatography with mass detector (CGMS). In addition, it was done biomechanical measurements (Corneometer, Sebumeter and TEWL) on interscapular region at initial and 6h for comparing. Resulting that the phases of the cycle did not affect the biomechanical variables (p > 0.05) when analyzed individually. For measurements in the forearm, Corneometry index (p < 0.001) and TEWL (p=0.011) in the treated area were higher than the control. The average of the Sebumetry, Corneometry indexes of the forearm treated was lower (p <0.001) than the interscapular region. In the analysis of chromatographic, there was a standard response at different stages of the menstrual cycle, however the analysis by individual had no a pattern response to the release of aromatic compounds. The correlations between sensory and instrumental (chromatography and biomechanical properties) did not observe any correlation (p> 0.05). But when considering chromatography as the response variable as a function of the menstrual cycle and the sensory evaluation, the follicular phase was higher than the Menstrual and Ovulatory phase (p=0.003). There was a strong positive correlation between sensory analysis and evaluation on men skin (p<0.001). However, the intrinsic factor of the individual woman influenced the response, leading to large response variability; however, see clearly that sex hormones interfere in the sensory response, chromatographic and biomechanics of the skin.
5

Estudo da correlação instrumental e sensorial de uma composição aromática aplicada na pele em função do ciclo menstrual / Study of instrumental and sensory correlation of a aromatic composition on the skin in function of mentrual cycle.

Claudia Silva Cortez Pereira da Costa 19 December 2013 (has links)
A área de perfumaria no mundo vem se desenvolvendo a cada dia buscando maior conhecimento das matérias-primas aromáticas, desde suas reações, estabilidade até suas interações com o substrato onde é aplicado, sempre em busca do conhecimento de todas as variáveis que possam influenciar a relação perfume-substrato e a aceitação dos consumidores, medida por meio da avaliação sensorial. Apesar de muitos estudos sobre a relação perfume-pele, poucos envolveram a relação com ciclo menstrual. Neste estudo o objetivo foi correlacionar às análises sensorial e instrumental (medidas biomecânicas e cromatográficas), estudar as matérias-primas aromáticas em função do ciclo menstrual. O estudo envolveu indivíduos com idade entre 18-40 anos: 29 mulheres e 3 homens, estes usados como grupo controle. Cada voluntária teve 40 &#181;l da composição aromática Ciclo 1910 aplicado no antebraço, onde foram feitas as medidas biomecânicas (corneometria, sebumetria e TEWL) nos tempos inicial e 6h. Nos tempos inicial, 1.5h, 3h, 4,5h e 6h se auto-avaliaram sensorialmente a intensidade de perfume por meio de escala sensorial de magnitude rotulada (LMS) e foram coletados os compostos aromáticos liberados pela técnica de headspace e analisados por espectrometria com cromatografia a gás e detetor de massa (CGMS). Realizou-se também medidas biomecânicas de corneometria, sebumetria e TEWL interescapulares em 5 voluntárias nos tempos inicial e 6h para comparação. Os resultados obtidos foram que as fases do ciclo não interferiram nas variáveis biomecânicas (p>0,05) quando analisadas isoladamente. Para as medidas realizadas no antebraço, os índices de Corneometria (p<0,001) e TEWL (p: 0,011) na região tratada apresentou média maior que a do controle. A média dos índices de Corneometria e Sebumetria da região do antebraço tratada foi menor (p<0,001) que da região interescapular. Na análise cromatográfica não houve um padrão de resposta em diferentes fases do ciclo. As correlações entre a avaliação sensorial e instrumental (cromatografia e propriedades biomecânicas) não observaram nenhum nível de correlação (p>0,05). A Cromatografia (dados cromatográficos) foi maior na fase Folicular que nas fases Menstrual e Ovulatória (p=0,003), ao considerar como variável resposta em função do ciclo menstrual e da avaliação sensorial. Houve uma forte correlação positiva entre a análise sensorial e a avaliação na pele do homem (p<0,001). No entanto, o fator intrínseco do indivíduo Mulher influenciou na resposta, ocasionando grande variabilidade, porém percebeu-se claramente que os hormônios sexuais interferiram na resposta sensorial, cromatográfica e biomecânica da pele. / The perfumery in the world has been developed everyday bringing more knowledge about aromatic raw-materials, as from chemistry reactions, stability until their interactions with substrate where is applied, always looking for variables could influence in the relation perfume-substrate and consumer acceptability, measured by sensory evaluation. Despite a lot of studies were done on this subject, few involved effects as function of menstrual cycle. The aim of this study was to correlate sensory and instrumental analysis (biomechanical and chromatographic measurements), to study the olfactory profile of raw materials in function of menstrual cycle. The study involved people with 18-40 years old: 29 volunteers, three men, who were used as control group. Each volunteer had 40 &#181;l of perfume applied on forearm, where were done Biomechanical measurements (Corneometer, Sebumeter and TEWL) at initial and 6h, At time initial, 1.5h, 3h, 4.5h and 6h; they did self-sensory assessment in perfume intensity in own forearm using labeled magnitude scale (LMS) and also where aromatic compounds released were collected by headspace technique spectrometry and gas chromatography with mass detector (CGMS). In addition, it was done biomechanical measurements (Corneometer, Sebumeter and TEWL) on interscapular region at initial and 6h for comparing. Resulting that the phases of the cycle did not affect the biomechanical variables (p > 0.05) when analyzed individually. For measurements in the forearm, Corneometry index (p < 0.001) and TEWL (p=0.011) in the treated area were higher than the control. The average of the Sebumetry, Corneometry indexes of the forearm treated was lower (p <0.001) than the interscapular region. In the analysis of chromatographic, there was a standard response at different stages of the menstrual cycle, however the analysis by individual had no a pattern response to the release of aromatic compounds. The correlations between sensory and instrumental (chromatography and biomechanical properties) did not observe any correlation (p> 0.05). But when considering chromatography as the response variable as a function of the menstrual cycle and the sensory evaluation, the follicular phase was higher than the Menstrual and Ovulatory phase (p=0.003). There was a strong positive correlation between sensory analysis and evaluation on men skin (p<0.001). However, the intrinsic factor of the individual woman influenced the response, leading to large response variability; however, see clearly that sex hormones interfere in the sensory response, chromatographic and biomechanics of the skin.
6

Volatile compounds in some eastern Australian Banksia flowers

Tronson, Deidre A., University of Western Sydney, Hawkesbury, College of Science, Technology and Environment, School of Science, Food and Horticulture January 2001 (has links)
This project was the very beginning of research into the chemistry of eastern Australian banksia flowers. Using dynamic headspace sampling (DHS) analysis, differences in volatile components, consistent with detection of differences in odour, were detected among three different species and one commercial cultivar. Infraspecific variation was also observed between two known subspecies of Banksia ericifolia and between differently coloured forms of Banksia spinulosa var. collina. The cultivar, Banksia 'Giant Candles', was shown to have some of the chemical components of each of its supposed ancestors. The absence of known wound-response chemicals indicated that this DHS method was successful in leaving the inflorescences undamaged throughout the sampling procedure. The Likens-Nickerson modification of classical hydrodistillation methods was useful. The static headspace method (SHS) was easily automated and was shown to be chemically robust and sufficiently sensitive to detect volatile compounds from only a few flowers. The milder DHS method, which minimised mechanical and heat damage to the plant tissue, produced a different set of results. From the results of this project, a suite of volatile compounds has been proposed that may be useful in future behavioural studies to help determine whether animals are attracted to components of banksia odours. These candidates include some compounds that have been reported in animal secretions, wound-response chemicals that may be produced by the plant to aid its communication with other organisms, and a compound (suggested to be sulfanylmethyl acetate) not previously reported from natural sources. The mildest of the three analytical methods used, dynamic headspace sampling, was shown to be suitable for the potential chemotaxonomic evaluation of some members of the Banksia genus. / Doctor of Philosophy (PhD)
7

Dispositivos hifenados para microextração em fase solida / Hyphenated devices for solid phase microextraction

Silva, Rogerio Cesar da 18 March 2005 (has links)
Orientador: Fabio Augusto / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T15:09:26Z (GMT). No. of bitstreams: 1 Silva_RogerioCesarda_D.pdf: 4524361 bytes, checksum: 24333539b89a414df416bbcf9e0ee5bd (MD5) Previous issue date: 2005 / Doutorado / Quimica Analitica / Doutor em Quimica
8

The Characterisation and Development of a Passivated Inlet to Selected Ion Flow Tube Mass Spectrometry (SIFT-MS)

Reed, Christine Jane January 2010 (has links)
SIFT-MS is a relatively new trace gas analysis technique that has wide application. One particular attribute of the instrument is the ability to detect and quantify volatile organic compounds to the parts per trillion in real-time without the need for sample preparation. However the issue of maintaining accuracy at these low concentrations required attention as it was evident large or polar analytes were being lost by adsorption to the SIFT instrument’s inlet system. The purpose of this research was to evaluate the performance of a passivated inlet in lowering any adsorption in the inlet system compared to the current unpassivated inlet of the SIFT instrument. Volatile concentrations of vanillin (C₈H₈O₃ 152.15 g/mol), ammonia (NH₃ 17.03 g/mol), and hydrogen sulfide (H₂S 34.08 g/mol) were measured. The results determined the passivated inlet provided a significantly better inlet response to these compounds. Consequently improved passivated inlets were installed on current models of SIFT-MS VOICE200®, and also the research laboratory VOICE100™ instrument. Having established a more reliable sampling system for very low concentrations of analyte, attention was paid to SIFT-MS flavour analysis of two foods, cheese and chocolate. The volatile matrix of these foods is highly complex and the compounds of interest are typically difficult to measure. The key aroma compounds for analysis were based on reported literature and earlier SIFT-MS studies which provided a useful framework for the current food flavour research. A significant finding from the SIFT-MS examination of Parmesan cheese is that differences in the relative concentration of some characteristic aroma compounds were a consequence of the milk type used in manufacture. Endogenous enzymes responsible for a multitude of reactions are mostly if not completely inactivated by the pasteurization temperature. A similar analysis approach was attempted for chocolate analysis. Here flavour differences were not as clearly recognised as for the cheese samples. In chocolate there are a greater number of parameters that are involved in its manufacture. Nevertheless, some recognisable differences in chocolate could be attributed to cocoa bean type and flavour additions by the manufacturer.
9

Einsatzmöglichkeiten der Headspace-Festphasenmikroextraktion (HS-SPME) zum Nachweis von forensisch-toxikologisch relevanten Verbindungen in biologischen Matrices

Junker, Heike Pauline. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2004--Bonn.
10

Inlet monitoring of a potable water supply using a sensor array

Hogben, Peter James January 2003 (has links)
Monitoring for pollutants in potable water is an area of interest and concern for water supply companies. Supply of sub-standard water can draw complaints from public and industrial customers. Water and water tainted with pollutants were used to assess the application of a non-specific chemical sensor array (eNose) to monitor for changes in the headspace generated from a flow-cell by means of statistically designed experiments. 2-chlorophenol and diesel were used to further assess trends in headspace generation during trials where different combinations of sampling parameters were applied. Field trials were conducted in accordance with the most suitable methodology determined during initial studies under laboratory conditions. The headspace is generated by bubbling nitrogen through the flow-cell containing a water sample. The liquid sample is flushed and regenerated after each sensor acquisition cycle. The resultant headspace sample is transferred to the sensor array module where the resistance of the conducting polymer sensors is monitored as they are exposed to each respective headspace sample. The change in each sensor resistance after 60 seconds of exposure is used to represent the headspace character. Subsequent acquisitions are added to a data set and then presented graphically. Sudden changes in the sensor resistance plots represent changes in water quality. The results showed that the developed apparatus and sampling methodology can determine the presence or absence of pollution in a water matrix. Laboratory analysis showed that detection levels for 2-chlorophenol and diesel were both &lt;5 ppm in the mixed stream. Future developments should focus on increasing the sensitivity of the system by concentrating the pollutants in either the liquid or gas phase or by modifying the sampling protocol to enable sensor recognition at lower concentration levels. The sensor array could act as a screening technique to support quantitative and characterising analytical equipment at the abstraction point. Establishing a pollution alarm limit, within the bounds of acceptable system variation, would enable conventional analytical techniques to remain on standby until activated by a statistically significant change in water quality. Once established continued testing would enable alarm levels to be incorporated into a contaminant database for additional pollutant compounds and combinations of known taste and odour causing compounds.

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