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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

Ecologia química como um mediador na atratividade de fêmeas Centris analis (Hymenoptera, Apidae) para colonização de ninhos, criação e manejo / Chemical ecology as a mediator in the attractiveness of Centris analis (Hymenoptera, Apidae) females for nest colonization, rearing and management

Sousa, Paulo Herbesson Pereira de January 2017 (has links)
SOUSA, Paulo Herbesson Pereira de. Ecologia química como um mediador na atratividade de fêmeas Centris analis (Hymenoptera, Apidae) para colonização de ninhos, criação e manejo. 2017. 68 f. Dissertação (Mestrado em Zootecnia)– Universidade Federal do Ceará, Fortaleza, 2017. / Submitted by Francisca Gomes (francisbeserra@yahoo.com.br) on 2017-06-27T18:09:08Z No. of bitstreams: 1 2017_dis_phpsousa.pdf: 2099417 bytes, checksum: 71080e1991836276fde90bfc11985473 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-07-06T20:46:38Z (GMT) No. of bitstreams: 1 2017_dis_phpsousa.pdf: 2099417 bytes, checksum: 71080e1991836276fde90bfc11985473 (MD5) / Made available in DSpace on 2017-07-06T20:46:38Z (GMT). No. of bitstreams: 1 2017_dis_phpsousa.pdf: 2099417 bytes, checksum: 71080e1991836276fde90bfc11985473 (MD5) Previous issue date: 2017 / Raising and managing Centris analis bees is facilitated by the use of trap nests, however, there is few number of research regarding factors that may influence the process of attracting nest-founding females. The present study aimed to identify volatile organic compounds (VOCs) existing in nests of C. analis, by employing the solid-phase microextraction (SPME) in order to learn about those compounds and variations of their chemical composition. This study also intended to optimize an extraction method for VOCs in food samples of immature C. analis. We made use of three types of fiber: apolar PDMS (Polydimethylsiloxane), bipolar CAR/PDMS (Carboxen/Polydimethylsiloxane), and bipolar DVB/CAR/PDMS (Divinylbenzene/Carboxen/Polydimethylsiloxane). We identified 27 compounds bellowing to those chemical classes. Among the compounds; trans-nerolidol (67,15%), detected by the PDMS fiber; hexanal (12,72%) and 3-methyl-1-butanol acetate (10,95%), detected by CAR/PDMS fiber; were the most representative for this sample. CAR/PDMS fiber was more selective extracting 20 compounds, DVB/CAR/PDMS and PDMS, 17 and 10 respectively. CAR/PDMS proved to be the most suitable for the extraction of VOCs in nests of Centris analis. When using CAR/PDMS fiber, we identified 40 VOCs belonging to nine chemical classes in food samples, oil and resin, used nest, and larvae. The major compounds cis-β-ocimene (35,7%), 2-Ethyl-1-hexanol (30,24%), p-xylene (24,59%) and 1-Octanol (20,63%), were detected in samples of oil, resin, used nest, and larvae, respectively. We noticed an existing variation in the diversity of volatile compounds according to larval and nest development, besides, certain compounds linger in the nest after emergence. / A criação e o manejo de abelhas Centris analis é facilitada pela utilização de ninhos armadilha, porém há poucas pesquisas sobre os fatores que possam influenciam no processo de atração de fêmeas fundadoras. O presente estudo teve como objetivo identificar os compostos orgânicos voláteis (COVs) presente no ninho de C. analis, utilizando a microextração em fase sólida (SPME) a fim de conhecer tais compostos e as variações na sua composição química. Este estudo buscou também, otimizar um método para extração dos COVs a partir de amostras do alimento de imaturos de C. analis. Utilizou-se três tipos de fibras: PDMS (Polidimetilsiloxano) apolar, CAR/PDMS (Carboxen/Polidimetilsiloxano)bipolar e DVB/CAR/PDMS (Divinilbezeno/Carboxen/Po lidimetilsiloxano) bipolar. Foram identificados 27 compostos pertencentes a cinco classes químicas. Entre os compostos, trans-nerolidol (67,15%) detectado pela fibra PDMS, hexanal (12,72%) e acetato de 3-metil-1-butanol (10,95 %) detectados pela fibra CAR/PDMS, foram os compostos de maior representatividade para esta amostra. A fibra CAR/PDMS foi mais seletiva, extraindo 20 compostos, DVB/CAR/PDMS e PDMS, 17 e 10 respectivamente. A fibra CAR/PDMS mostrou-se como mais indicada para extração de COVs em ninhos de Centris analis. Utilizando-se a fibra CAR/PDMS, foram identificados 40 COVs pertencentes a nove classes químicas em amostra de alimento, óleo e resina, ninho usado e lavas. Os compostos majoritários cis-β-ocimeno (35,7%), 2-Etil-1-hexanol (30,24%), p-xileno (24,59%) e 1-Octanol (20,63%), foram detectados em amostra de óleo e resina, ninho usado e lavas respectivamente. Verificamos que há uma variação na diversidade de composto voláteis segundo o desenvolvimento larval e do ninho e que determinados compostos permanecem no ninho após a emergência.
2

Variables Affecting the Collection and Preservation of Human Scent Components through Instrumental and Biological Evaluations

Hudson, Davia Tamar 12 March 2009 (has links)
In certain European countries and the United States of America, canines have been successfully used in human scent identification. There is however, limited scientific knowledge on the composition of human scent and the detection mechanism that produces an alert from canines. This lack of information has resulted in successful legal challenges to human scent evidence in the courts of law. The main objective of this research was to utilize science to validate the current practices of using human scent evidence in criminal cases. The goals of this study were to utilize Headspace Solid Phase Micro Extraction Gas Chromatography Mass Spectrometry (HS-SPME-GC/MS) to determine the optimum collection and storage conditions for human scent samples, to investigate whether the amount of DNA deposited upon contact with an object affects the alerts produced by human scent identification canines, and to create a prototype pseudo human scent which could be used for training purposes. Hand odor samples which were collected on different sorbent materials and exposed to various environmental conditions showed that human scent samples should be stored without prolonged exposure to UVA/UVB light to allow minimal changes to the overall scent profile. Various methods of collecting human scent from objects were also investigated and it was determined that passive collection methods yields ten times more VOCs by mass than active collection methods. Through the use of polymerase chain reaction (PCR) no correlation was found between the amount of DNA that was deposited upon contact with an object and the alerts that were produced by human scent identification canines. Preliminary studies conducted to create a prototype pseudo human scent showed that it is possible to produce fractions of a human scent sample which can be presented to the canines to determine whether specific fractions or the entire sample is needed to produce alerts by the human scent identification canines.
3

Využití různých extrakčních technik pro analýzu výluhů z biouhlu / Use of various extraction techniques for the analysis of biochar extracts

Jakubčeková, Kristína January 2021 (has links)
Biochar is a material whose properties, composition and impact on the environment are often discussed nowadays. The reason is its application as a soil conditioner. This leads to the need for qualitative as well as quantitative knowledge of its composition. This diploma thesis focuses on the qualitative analysis of biochar leachates processed by various extraction techniques. To approximate the real conditions, six aqueous mediums with different pH values is used, which a solid sample of biochar is exposed to. The prepared leachates are after that processed by extraction techniques, which are solid phase microextraction (SPME), single drop microextraction (HS-SDME), solid phase extraction (SPE) and liquid-liquid extraction (LLE). Analysis of the extracts was performed by gas chromatography-mass spectrometry (GC/MS). The measurements showed that the HS-SDME technique did not show a response. SPE was a rapid technique, but compared to other techniques, it acquired a smaller range of substances. Liquid-liquid extraction, a time-consuming technique, did not obtain as much analytes as SPME. By comparing these applied techniques, the SPME technique is the best choice. The most common determined analytes were those from the group of ketones and carboxylic acids and their derivatives.
4

The Detection of an Invasive Pathogen through Chemical and Biological Means for the Protection of Commercial Crops

Simon, Alison G 22 September 2017 (has links)
Standoff detection of targets using volatiles is essential when considering substances that are hazardous or dangerous, or for which the presence or location is unknown. For many invasive biological threats, their presence is often not realized until they have begun visibly affecting and spreading through crops or forests. The fungus Raffaelea lauricola is a biothreat vectored by the invasive beetle Xyleborus glabratus, or redbay ambrosia beetle (RAB), whose presence in avocado groves is currently detectable by visual inspection. Once visually identified, the affected trees must be removed and destroyed to protect those remaining trees. However, if the fungus is identified via standoff volatile detection, there is anecdotal evidence that it can be treated with propiconazole and saved from progression to the fatal laurel wilt disease. As a result of the rapid spread of R. lauricola and the quick death of trees, early detection through standoff methods is essential. The only current method of pre-symptomatic identification is canine detection. Canines are sensitive and selective biological detectors that can trace odors to their source, despite the presence of a variety of background odors. The present research evaluated the volatile organic compounds (VOCs) of the laurel wilt disease and R. lauricola using headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Additionally, a new method for odor collection and presentation to trained detection canines was developed. Knowledge of the disease and standoff volatile detection capabilities are improved using this information.
5

Metabolômica aplicada à identificação de biomarcadores nas espécies frutíferas Eugenia uniflora L. e Passiflora spp.

Mesquita, Paulo Roberto Ribeiro de 30 September 2016 (has links)
Submitted by Paulo Mesquita (prrmesquita@gmail.com) on 2016-10-18T17:10:54Z No. of bitstreams: 1 Tese Doutorado Mesquita_FINAL.pdf: 3135632 bytes, checksum: dd198da88e048f82bac99316af7e483b (MD5) / Approved for entry into archive by Uillis de Assis Santos (uillis.assis@ufba.br) on 2016-10-18T17:18:46Z (GMT) No. of bitstreams: 1 Tese Doutorado Mesquita_FINAL.pdf: 3135632 bytes, checksum: dd198da88e048f82bac99316af7e483b (MD5) / Made available in DSpace on 2016-10-18T17:18:46Z (GMT). No. of bitstreams: 1 Tese Doutorado Mesquita_FINAL.pdf: 3135632 bytes, checksum: dd198da88e048f82bac99316af7e483b (MD5) / FAPESB e CNPq. / O comércio de frutas tropicais, principalmente das regionais e exóticas, apresenta-se como uma grande oportunidade para produtores e outros profissionais brasileiros. No entanto, a sua comercialização tem crescido aquém das expectativas devido, em certa parte, à necessidade de maior fomento a pesquisas relacionadas a estas espécies frutíferas e seus possíveis produtos derivados. Entre as diversas abordagens que estão sendo estudadas na área agrícola, se destacam a caracterização dos metabólitos presentes nas diferentes espécies de plantas de interesse econômico, o entendimento do papel biológico dos mesmos e possíveis alterações neste metaboloma gerados por ataques de diferentes tipos de patógenos. Este trabalho teve como objetivo caracterizar os metabólitos presentes na pitangueira (Eugenia uniflora L.) e diferentes tipos de maracujazeiros (Passiflora spp.), e avaliar possíveis mudanças no perfil destes compostos. Foram determinados os perfis de compostos orgânicos voláteis (COVs), extraídos de folhas de E. uniflora de plantas que apresentavam diferentes biotipos de cor dos seus frutos (laranja, vermelho ou roxo), coletadas em diferentes regiões da Bahia. Os compostos foram extraídos e identificados através da técnica HS-SPME/GC-MS e o perfil das amostras foi avaliado através de técnicas de análise multivariada (PCA e HCA). Através das técnicas aplicadas foi possível identificar 33 compostos nas plantas com cada biotipo de cor de fruto e discriminar entre os três grupos de amostras com base neste perfil de metabólitos. Também foram extraídos e caracterizados, utilizando a técnica HS-SPME/GC-MS, os perfis de COVs de cinco espécies do gênero Passiflora: P. edulis, P. cincinnata, P. maliformis, P. gibertii e P. setacea. Em seguida avaliou-se alterações no perfil de COVs destas espécies após infecção pelo Cowpea aphid-borne mosaic virus (CABMV). Blocos de 4 plantas sadias e inoculadas com o CABMV foram mantidas em casa de vegetação e fitotron, sob condições controladas. Também foram avaliadas mudanças no perfil de compostos em P. cincinnata até o 28º dia após a inoculação com o CABMV. Foram identificados 43 COVs nas cinco espécies de Passiflora e a utilização das técnicas de análise multivariada (PCA, PLS-DA e HCA) permitiu discriminar entre as amostras sadias e infectadas pelo CABMV nas diferentes espécies, através do seu perfil de metabólitos. Além disso, foi possível identificar potenciais biomarcadores de infecção ao CABMV comuns e específicos para cada uma das cinco espécies. Ao avaliar a infecção de plantas da espécie P. cincinnata em diferentes períodos, se verificou que a partir de 3 dias de inoculação já é possível distinguir claramente o perfil das amostras infectadas comparado ao das amostras sadias. A abordagem metabolômica utilizada neste trabalho possibilitou identificar diferentes tipos de biomarcadores, tanto de espécies de Passiflora quanto prováveis variedades de E. uniflora para estudos de quimiotaxonomia, além de metabólitos sinalizadores de infecção pelo CABMV em Passiflora spp. / The trading of regional and exotic tropical fruits can be presented as a great opportunity for producers and other Brazilian professionals. However, their marketing has grown short of expectations due to some part to the need for higher encouragement of research related to these fruit species and its possible derivatives. Among the various approaches being studied in agriculture, stand characterization of metabolites present in different plant species of economic interest, understanding of the biological role of these and possible changes in the metabolome of different types generated by pathogen attacks. This study aimed to characterize the metabolites present in the species Eugenia uniflora L. and species of Passiflora, and evaluate possible changes in the profile of these compounds. It was determined the profiles of VOCs extracted from E. uniflora leaves of plants showing different color biotypes of its fruits (orange, red or purple), collected in different regions of Bahia. The compounds were extracted by HS-SPME/GC-MS technique and the profile of the samples was evaluated using multivariate analysis (PCA and HCA). Through the techniques applied were identified 33 compounds in plants with each fruit color biotype and discriminate between the three groups of samples based on this metabolite profile. Also were characterized using the HS-SPME/GC-MS technique, the VOC profiles of five species of the genus Passiflora: P. edulis, P. cincinnata, P. maliformis, P. gibertii and P. setacea. Then we evaluated changes in VOC profile of these species after infection by Cowpea aphid-borne mosaic virus (CABMV). Blocks of four healthy and inoculated plants with CABMV were kept in a greenhouse and phytotron, under controlled conditions. They evaluated changes in compounds profile in P. cincinnata until the 28th day after inoculation with CABMV. Were identified 43 VOCs in five species of Passiflora spp. and use of multivariate analysis (PCA, PLS-DA and HCA) allowed the discrimination between healthy and infected with CABMV samples in different species, through its metabolite profile. Moreover, it was possible to identify potential biomarkers of infection CABMV the common and specific to each of the five species. When evaluating infection of plants of the species P. cincinnata at different times, it was found that from 3 days of inoculation is already possible to distinguish the profile of the infected sample compared to the healthy samples. The metabolomic approach used in this study enabled us to identify different types of biomarkers, both species of Passiflora spp. as likely varieties of E. uniflora for chemotaxonomy studies, besides flags metabolites of infection by CABMV in Passiflora spp.
6

Srovnání obsahu aromaticky aktivních látek vybraných typů sýrů / Comparison of aroma active compounds of selected types of cheese

Brožová, Michaela January 2018 (has links)
This diploma thesis deals with the determination of aroma active substances in selected white mold cheeses, which are/are not awarded with the „Protected Designation of the European Union“ and their mutual comparison. In the theoretical part cheeses are characterised , including general production technology. The white mold cheeses are then described in detail. This is followed by the literary search dealing with the problematic of aroma active substances in cheeses. In conclusion of the theoretical part the method of their determination using solid phase microextraction and gas chromatography with mass detection is described. The SPME-GC- MS method was chosen for the experimental part of the determination of aroma active substances in selected white mold cheeses. A total of 12 cheeses were analyzed, of which 6 were Czech and Slovak and 6 were French with a protected designation of origin. The differences between individual samples were found in the number and type of the identified volatile compounds. A total of 78 volatiles were identified in selected cheeses, of which 20 were alcohols, 19 esters, 12 ketones, 11 acids, 4 sulfur compounds, 3 hydrocarbons, 3 lactones, 2 aldehydes, 2 phenols, 1 nitrogen compound. The cheeses were compared in terms of the identified compounds, and finally the results were statistically evaluated by the PCA method.
7

Charakterizace a průběh zrání sýrů eidamského typu / Characterisation and maturation process of Edam type cheese

Dostálková, Andrea January 2019 (has links)
This diploma thesis deals with the assessment of aroma compounds and free/bound fatty acids in model samples of Edam type cheeses. Various combinations of microbial cultures, basic mesophilic and four selected strains of thermophilic Lactobacillus casei and Lactobacillus plantarum, were used for cheese production. The main aim was to judge the influence of microbial cultures on content of measured parameters, the changes during ripening were also followed. The HS-SPME-GC-MS method was used for identification and semiquantification of aroma compounds. The lipids from cheese were extracted based on ISO 1735:2004, fatty acids were identified and quantified using GC-FID method after conversion to methyl esters by acid esterification with boron trifluoride in methanol. In total 50 volatile compounds were identified in samples, 11 alcohols, 5 aldehydes, 7 ketones, 6 acids, 10 esters, 3 lactones, 2 sulphur compounds and 6 „others“; all of them are considered as aroma active. About 30–40 compounds were identified in single samples, alcohols, acids and ketones were the predominant. The number as well as the content of compounds identified decreased slightly during ripening. In total 17 free/bound fatty acids were identified in samples, their content also decreased during ripening. Myristic, palmitic, stearic and oleic acids were the predominant. The significant differences (p
8

Problematika produktů osobní péče ve složkách životního prostředí / Personal care products as environmental contaminants

Babuš, Ondřej January 2010 (has links)
Synthetic musk compounds were first prepared artificially in the late 19th century. They have been used to perfume cosmetics, detergents and personal care products. The attention of many researchers has been focused on it recently, due to its high penetration into the nature which is a logical consequence of its great use. The main goal of this thesis is to determine the effect of the ultrafiltration on the concentration reduction of substances mentioned above in the industrial waste waters produced by the cosmetic company. Analytes from the sample were extracted using solid phase microextraction (SPME) and on gas chromatography analysis with mass spectroscopy (GC / MS) has been performed. The whole method was optimized and evaluated. Determination of the average efficiency of the ultrafiltration was made based on data obtained before and after ultrafiltration. Such efficiency determines the suitability of use of this method for removal of synthetic musk compounds from waste waters.
9

Stanovení syntetických vonných látek v odpadních vodách / Assessment of synthetic musk compounds in waste waters

Štefka, Michal January 2012 (has links)
The synthetic aromatic substances are present in the products of personal hygiene, detergents and cosmetics. After the application these compounds are drained away into the waste water. But the technological process used in sewage works is not able to eliminate these substances and these ones influence the particular items of the environment. The aim of the degree work is the determination of four selected items of the linear musk compounds (2-cyclohexylethanole, Fresco Menthe, Citronellol and Isobornyl acetate) in the wastewater. The real patterns were taken on the place of affluent of the sewage discharge and on the place of the draining off in the sewage plant in VFU Brno. On the basis of measurements and subsequent evaluation on of obtaining data it was possible to express the measurement of efficiency of the elimination of the present musk compounds. Firstly it was necessary to adapt the selected analytical method to the physical and chemical qualities of the prescribed analytes. The analytes were extracted from the patterns by the method of the micro extraction for the consistent phase so called solid phase microextraction (SPME). The gas chromatography in the tandem connection with the mass spectrometry makes the identification and quantification possible.
10

Sledování vlivu kvasinek na chemické a senzorické vlastnosti vyráběného vína / Monitoring of the influence of yeasts on the chemical and sensory qualities of manufactured wine

Petrášová, Ludmila January 2016 (has links)
The thesis deals with monitoring of the yeast's impact to the chemical and sensorial characteristics of produced wine. The aim of experimental part was obtaining of the aroma-active substances in the fermenting must and wine Hibernal and wine Pinot Blanc. SPME-GC-MS methods were used for identify wines and must aroma. The same autochthonous yeasts were used for wine production. This yeast was isolated from surface of grapes in our laboratory. It was found that both wines have a similar aromatic profile. The next aim was the monitoring of chemical parameters of samples and their changes. For this measurement were used spectrophotometric methods and HPLC methods. The last goal of the thesis was the isolation and identification of yeasts from wine Pinot Blanc by PCR-RFLP. These yeasts were then compared with yeasts isolated from Hibernal must. Identification of yeasts were done by amplification 5,8S-ITS DNA stretches using primers ITS1 and ITS4. Restriction endonuclease HaeIII, HinfI, HhaI and TaqI. were used for restriction analysis then.

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