• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 150
  • 40
  • 39
  • 16
  • 15
  • 9
  • 7
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • Tagged with
  • 339
  • 339
  • 339
  • 43
  • 42
  • 41
  • 37
  • 35
  • 35
  • 33
  • 33
  • 31
  • 30
  • 30
  • 30
  • 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.
121

Power output and tissue oxygenation of women and girls during repeated Wingate tests and recovery

Medd, Emily 22 December 2015 (has links)
The purpose of this study was to compare the exercise and recovery muscle oxygenation response of Women and Girls during two 30s Wingate anaerobic tests separated by two minutes of active cycling recovery (resistance ≈ 2.5% body weight, 60-80rpm). Oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (HHb), total hemoglobin (tHb), and tissue saturation index (TSI) were monitored at the right vastus lateralis muscle using near infrared spectroscopy (NIRS) throughout exercise, recovery, and a post-exercise femoral artery occlusion to TSI plateau. Pressure was preset at 250mmHg for Women and 210mmHg for Girls, achieved by rapid inflation in 0.3 seconds, and maintained until a 2 minute TSI plateau occurred or 10 minutes had passed. Twenty Women (23.8[2.12] years) and 13 Girls (9[1] years, combined Tanner stage <4) completed all tasks excepting 1 girl who did not complete occlusion. Significant group, time, and group by time interaction effects were observed for peak and mean power (Watts.kgFFM-1). Women had significantly greater power output compared to Girls for both Wingates. While both groups had reduced power output in Wingate 2, the reduction was significantly greater in Women compared to Girls. No significant group differences were found for resting TSI, recovery TSI, minimum TSI during either Wingate test, or for minimum TSI during occlusion, however a time main effect for Women was observed with minimum TSI being significantly lower in Wingate 1 compared to Wingate 2. Girls had similar minimum TSI for both Wingate tests. Women also demonstrated a significantly greater difference between Wingate minimum TSI and occlusion minimum TSI in Wingate 2 compared to Wingate 1. During Wingate 1, HHb increase was greater in Girls compared to Women and remained elevated during recovery compared to women. Changes in HbO2, HHb, and tHb were reduced in Wingate 2 for both groups, more so in Women for tHb and in Girls for HHb. Recovery was not different between groups with the exception of a faster TSI time constant of recovery in Women (τ =20.25 [13.01]s) compared to Girls (τ =36.77 [13.38]s) which is attributed to a faster HHb time constant in Women (τ =13.6 [0.44]s) compared to Girls (τ =30.77[19.47]s). Both groups demonstrated similar power output results and TSI response across the two Wingate tests but Girls were better able to repeat the anaerobic performance with a consistent TSI minimum between the two tests despite a faster recovery of HHb and TSI in women. These findings, in the context of observed Hb variable differences between groups, provide evidence of greater oxidative metabolism in Girls during a high intensity exercise. / Graduate / December 18, 2016
122

Methods to determine spatial variations of herbicide and estrogen sorption coefficients in undulating to hummocky terrains for pesticide fate modeling at the large scale

Singh, Baljeet January 2014 (has links)
To reduce the uncertainty associated with pesticide fate model predictions on the large scale, a rapid method is needed that can generate sorption coefficients (Kd values) with sufficient spatial detail. The feasibility of near-infrared spectroscopy (NIRS) to act as such a method was examined, using weak-acidic (2,4-D), weak-basic (atrazine) and zwitterion (glyphosate) herbicides and the natural steroid estrogen (17β-estradiol). A total of 609 horizons in 140 soil profiles were collected in agricultural fields near Brandon, Manitoba and near Saskatoon, Saskatchewan. In both agricultural fields, Kd values in horizons generally increased in the order of 2,4-D < atrazine < 17β-estradiol < glyphosate. Soil organic carbon content (SOC) followed by the soil pH were the major factors controlling the sorption of 2,4-D, atrazine and 17β-estradiol but glyphosate showed very strong sorption to soil particles regardless of measured SOC and soil pH values. For the chemicals studied, Kd values decreased from A to C horizons regardless of the segment of the slope from which the soil samples were collected, with the exception of glyphosate that showed relatively large Kd values in B-horizons illuviated with clay. Both the Zeiss Corona and the Foss 6500 spectrophotometers produced significantly strong predictive models for soil properties and Kd values of 2,4-D, atrazine and 17β-estradiol. However, models for glyphosate Kd values were weak or not significant. Using a test set approach and either soil spectral or soil properties data as independent variables, partial least squares regressions were successfully developed to estimate Kd values for use in the Pesticide Root Zone Model (PRZM) to calculate the herbicide mass leached. The study concluded that the added benefit of NIRS will be most useful if the pesticides under study have small sorption potentials and short half-lives in soil. Regional approaches to predicting Kd values from NIRS spectral data can also be developed if the calibration model is derived by combining a set of fields where each has a similar statistical population characteristic in Kd values. / February 2016
123

Prediction of post-storage quality in canning apricots and peaches using near infrared spectroscopy (NIRS) and chemometrics

Myburgh, Lindie 12 1900 (has links)
Thesis (MSc Food Sc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Post-storage quality of the stone fruit, apricots and peaches, is the major factor determining their suitability for canning after cold storage in South Africa. Short harvesting periods and the limited capacity of the factory to process the large quantities of fruit within two days after delivery, necessitates cold storage until canning. Apricots develop internal breakdown, whereas peaches develop internal breakdown accompanied by loosening of the skin and adhesion of the flesh to the stone. The deterioration takes place within the fruit during a cold storage period of one to two weeks. The tendency of the fruit to develop internal defects can, to date, not be identified prior to storage and are only discovered after destoning during canning. Near infrared spectroscopy (NIRS) combined with chemometrics were investigated as a non-destructive method to predict post-storage quality in Bulida apricots and clingstone peach cultivars. Near infrared (NIR) spectra (645-1201 nm), measured on the intact fruit just after harvesting, were correlated with subjective quality evaluations performed on the cut and destoned fruit after cold storage. The cold storage periods for apricots were four weeks (2002 season) and three and two weeks for peach cultivars for the 2002 and 2003 seasons, respectively. Soft independent modelling by class analogy (SIMCA) and multivariate adaptive regression splines (MARS) were applied to the spectral and reference data to develop models for good and poor post-storage quality. The ability of these models to predict post-storage quality was evaluated in terms of recognition (sensitivity) and rejection (specificity) of the samples in independent validation sets. Total correct classification rates of 50.00% and 69.00% were obtained with Bulida apricots, using SIMCA and MARS, respectively. Classification results with apricots showed that MARS performed better than SIMCA and is thus recommended for this application. Total correct classification rates of 53.00% to 60.00% (SIMCA) and 57.65% to 65.12% (MARS) were obtained for data sets of combined peach cultivars within seasons and over both seasons. Additional aspects of fruit quality were investigated to identify possible indices of post-storage quality. Classification trees were used to find correlations between the post-storage quality and the fruit mass, diameter, firmness and soluble solids content (SSC). Among these, fruit diameter and firmness were the major indices of post-storage quality. Accurate predictions of firmness could not be achieved by near infrared spectroscopy (NlRS), making the combination of NIRS and classification trees not yet suitable for predicting post-storage quality. NIRS was further used to predict poststorage SSC within seasons in Bulida apricots and intact peach cultivars. This confirmed sufficient NIR light penetration into the intact fruit and also provided a further application of NIRS for ripeness evaluation in the canning industry. Validations on peach samples obtained correlation coefficients (r) of 0.77-0.85 and SEP-values of 1.35-1.60 °Brix using partial least squares (PLS) regression. MARS obtained r = 0.77-0.82 and SEP = 1.42-1.55 °Brix. Predictions of sse in apricots were less accurate, with r = 0.39-0.88, SEP = 1.24-2.21 °Brix (PLS) and r = 0.51-0.82, SEP = 1.54-2.19 °Brix (MARS). It is suggested that the accuracy of sse measurements, and the subsequent predictions, were affected by the cold storage periods as well as internal variation within the fruit. This study showed that a combination of NIRS and chemometrics can be used to predict post-storage quality in intact peaches and apricots. A small scale feasibility study showed that 4% (R117 720) (apricot industry) and 3% (R610 740) (peach industry) of production losses can be saved if this method is implemented in the South African canning industry. Although it was difficult to assign specific chemical components or quality attributes to the formulation of the storage potential models, important hidden information in the spectra could be revealed by chemometric classification methods. NIRS promises to be a useful and unique quality evaluation tool for the South African fruit canning industry. Several recommendations are made for the canning practices to reduce losses and for future research to improve the current prediction models. / AFRIKAANSE OPSOMMING: Die kwaliteit van die steenvrugte, appelkose en perskes, is die hoof bepalende faktor vir hul geskiktheid vir inmaakdoeleindes na koelopberging in Suid-Afrika. Die vrugte moet opgeberg word by lae temperature vir een tot twee weke, aangesien die oestydperk kort is en die kapasiteit van die fabriek te beperk is om die groot hoeveeheid vrugte dadelik in te maak. Tydens hierdie opbergingstydperk vind agteruitgang in die vrugte plaas. Dit word in appelkose gekenmerk deur interne verval en in perskes gekenmerk aan interne verval, tesame met enlos skil en die vaskleef van die vrugvlees aan die pit. Tot dusver, bestaan daar geen metode om hierdie tipe agteruitgang in vrugte voor opberging te identifiseer nie. Dit word eers na opberging opgemerk wanneer die vrugte ontpit word. Naby-infrarooi spektroskopie (NIRS), gekombineerd met chemometriese metodes is gebruik om opbergingspotensiaal in Bulida appelkose en taaipitperske kultivars te bepaal. enKorrelasie is gemaak tussen naby-infrarooi (NIR) spektra, gemeet op die heel vrugte voor opberging en subjektiewe evaluering van kwaliteit, geïdentifiseer op die gesnyde vrugte na opberging. Die opbergingstydperke vir perskes was vir drie en twee weke vir die 2002 en die 2003 seisoene, onderskeldeflk, terwyl die appelkose vir vier weke opgeberg is. Twee chemometriese metodes, "soft independent modelling by class analogy" (SIMCA) en "multivariate adaptive regression splines" (MARS) is gebruik om die spektra en ooreenstemmende subjektiewe data te kombineer en modelle is ontwikkel vir goeie en swak opbergingspotensiaal. Die vermoë van die modelle om die vrugkwaliteit na die opbergingstydperk te voorspel, is geêvalueer in terme van herkenning en verwerping van vrugtemonsters in onafhanklike toetsstelle. Totale korrekte klassifikasies van 50.00% and 69.00% is verkry vir Bulida appelkose, met SIMCA en MARS, onderskeidelik. Die klassifikasie resultate het gewys dat MARS beter gevaar het as SIMCA en word dus sterk aanbeveel vir hierdie toepassing. Totale korrekte klassifikasies van 53.00% tot 60.00% (SIMCA) and 57.65% tot 65.12% (MARS) is verkry vir gekombineerde perskekultivars tussen seisoene en oor seisoene. Verdere aspekte van vrugkwaliteit is geêvalueer om enmoontlike indeks van opbergingspotensiaal te verkry. Klassifikasiebome is gebruik om en korrelasie te vind tussen kwaliteit na opberging en vrugmassa, deursnee, fermheid en totale oplosbare vastestowwe (TOV). Diameter en fermheid het die meeste gekorreleer met die kwaliteit na opberging. Voorspellings van fermheid deur die gebruik van naby infrarooi spektroskopie (NIRS) was ~gter nie akkuraat nie. Dus word die kombinasie van klassifikasiebome en NIRS om opbergingspotensiaal te voorspel nie tans aanbeveel nie. NIRS is verder gebruik om TOV te voorspel binne seisoene in heel Bulida appelkose en perskekultivars. Dit is uitgevoer om voldoende NIR ligpenitrasie in die vrugte te bevestig en ook om 'n verdere toepassing van kwaliteitsbepaling (as indeks van soetheid en rypheid) vir die inmaakindustrie te verskaf. Validasies is op perskemonsters uitgevoer en korrelasiekoêffisiente (r) van 0.77-0.85 en voorspellingsfoute van 1.35-1.60 °Brix is verkry met "partial least squares" (PLS) regressie. MARS het r = 0.77-0.82 and voorspellingsfoute = 1.42-1.55 °Brix verkry. Die akkuraatheid van die TOV meetings en gevolglike voorspellings is waarskynlik beïnvloed deur interne variasie binne die vrugte sowel as die opbergings tydperke wat verloop het tussen metings. Hierdie studie wys dat NIRS en chemometriese metodes wel gebruik kan word om opbergingspotensiaal in heel perskes in appelkose te voorspel. 'n Kosteberekening het gewys dat besparings van 4% (R117 720) (appelkoos industrie) en 3% (R610 740) (perske industrie) moontlik is indien NIRS en MARS geïmplementeer word. Alhoewel dit moeilik was om spesifieke chemiese komponente en .sekere kwaliteitsaspekte aan die ontwikkeling van die modelle te koppel, is belangrike verborge informasie in die spectra uitgebring deur chemornetriese metodes. NIRS beloof om 'n bruikbare en unieke kwaliteitskontrole maatstaf te wees vir die Suid-Afrikaanse inmaakindustrie. Verskeie aanbevelings is gemaak vir die inmaakpraktyke om verliese te voorkom en ook vir toekomstige navorsing om die huidige klassifikasiemodelle te verbeter.
124

Effects of Weathering on Thermally Modified Softwoods with different Surface Treatments

Hartwig, Marie January 2018 (has links)
This master’s thesis studies the effect of weathering on thermally modified Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) with different surface treatments. Most importantly colour changes were analysed, especially, the greying. However, other aspects of appearance changes, like cracks, mould and chemical changes on the surface were included. Special emphasis was on analysing the influence of tree species, type of thermal modification and surface treatment on these properties. Furthermore, it was tested if near infra-red (NIR) spectroscopy allows to estimate the colour, in addition, to measuring chemical changes. The whole study was set up as a decking of a gangway in Northern Sweden and evaluated after the first year of exposure. With the help of colorimetry, changes in colour based on the CIE L*C*hab colour space were measured. Test results showed that within one year all surfaces turned greyer significantly due to changes in content of lignin and cellulose measured with NIR spectroscopy. Differences could neither be observed between the uses of the two tree species nor between the uses of the thermal modifications, pressurised saturated steam at a temperature of 180 °C and superheated steam at a temperature of 212 °C. However, the surface treatment affects the colour change. Timber treated with a silicon based treatment had from the beginning a greyer colour and turned greyest after one year, while oil and pigmented oil stain slowed down the greying compared to untreated and iron vitriol treated timber. After one year of exposure for none of the treatments the colour had stabilised. Qualitative analysis of cracks and mould growth on the surface indicated some dependence on thermal modification and surface treatment. The PLS model for the prediction was not good, so no universally valid conclusions could be drawn of them. Timber with silicon based treatment showed a tendency for mould growth and timber thermally modified with pressurised saturated steam at a temperature of 180 °C tends to have cracks more often. It was possible to estimate the colour from NIR spectroscopy. Best estimations were achieved for the Chroma, followed by lightness and hue. Even better prediction of the Chroma could be achieved by fitting different models based on the surface treatments.  Hence, NIR spectroscopy allows a good estimation of the greying without needing a further measurement instrument, like a colorimeter.
125

Near-Infrared Spectroscopy neurofeedback (NIRS neurofeedback) em crianças com Transtorno de Déficit de Atenção/Hiperatividade (TDAH)

Londero, Igor January 2015 (has links)
As intervenções com neurofeedback têm tido grande difusão na área como uma alternativa possível para tratamento do Transtorno de Déficit de Atenção/Hiperatividade (TDAH). Este estudo tem o objetivo de avaliar a viabilidade da utilização de um sistema de neurofeedback de baixo custo chamado Near Infrared Spectroscopy/Hemoencephalography Neurofeedback (NIR/HEG-NF) para tratar crianças com TDAH. Método: trata-se de um estudo clínico piloto aberto, que incluiu 5 crianças (3 meninos e 2 meninas - idade 10,4 ± 0,89 anos) com TDAH-C (tipo combinado). Os indivíduos completaram um programa de 24 sessões de NIR/HEG-NF, duas ou três vezes por semana. Os seguintes desfechos foram avaliados pré e pós-tratamento: 1) sintomas de desatenção e hiperatividade; 2) desempenho neuropsicológico; 3) imagens de SPECT cerebral; 4) qualidade de vida; e 5) efeitos adversos. Resultados: houve maior resistência do que o esperado para a participação dos indivíduos devido a vários fatores, tais como logísticos para a participação nas sessões e requerimento de não uso de medicação durante o protocolo. Detectamos uma diferença significativa na comparação pré e pós-intervenção nos escores atribuídos pelos pais na dimensão de hiperatividade e impulsividade do Swanson, Nolan and Pelham Questionnaire (SNAP-IV) (p = .042; tamanho de efeito [ES] =.38) e uma tendência de melhora nos escores atribuídos pelos pais e professores na dimensão desatenção (p = .066; ES = .47 / p = .068; ES = .60) naquelas crianças que finalizaram o tratamento. Detectamos uma tendência de aumento perfusional em diferentes partes do córtex cerebral em três indivíduos. As comparações pré e pós-intervenção nas outras medidas não indicaram diferenças estatisticamente significativas. Não foram relatados efeitos adversos significativos. Discussão: Os achados iniciais sugerem que o NIR/HEG-NF como tratamento para sintomas de TDAH pode ser promissor e deve ser melhor investigado. O protocolo lança luz sobre novas abordagens para avaliar a eficácia da intervenção. Pode-se, por exemplo, implementar o programa de intervenção no ambiente escolar e com uso concomitante de medicamentos para superar as resistências na alocação de pacientes e para uma avaliação com maior validade externa. / Background and objectives: Neurofeedback interventions have been quick and extensively introduced for clinicians to treat Attention-Deficit/Hyperactivity Disorder (ADHD). This study aims to assess the feasibility of using a low cost neurofeedback system called Near Infrared Spectroscopy/ Hemoencephalography Neurofeedback (NIR/HEG-NF) for treating children with ADHD. Method: This open pilot clinical study included 5 children (3 boys and 2 girls - age 10.4 ± 0.89 years) with ADHD-C (combined type). The subjects completed a program of 24 sessions of NIR/HEG-NF, two or three times a week. The following outcomes were assessed pre and post-treatment: 1) clinical symptoms of inattention and hyperactivity; 2) neuropsychological performance; 3) brain SPECT images; 4) quality of life and; 5) adverse effects. Results: Higher resistance than expected was experienced for patient allocation due to logistic reasons to attend the sessions in the hospital and the requirement of not using medication during the protocol. We detected a significant decrease in hyperactivity/impulsivity comparing pre and post-intervention scores in the parent’s Swanson, Nolan and Pelham Questionnaire - SNAP-IV (p = .042; Effect Size [ES] r = .38) and a trend of improvement in scores attributed by parents and teachers in inattention (p = .066; r = .47 / p = .068; r = .68) . We detected a trend for increased perfusion in different parts of the entire cortex in 3 subjects. Comparisons between pre and post-intervention scores in other measures did not suggest meaningful differences. No significant adverse effects were reported. Discussion: Our initial findings suggest that NIR/HEG-NF technique might be promising and should be further investigated. The protocol shed light on new approaches to assess the effectiveness of the intervention such as the need to both implement the intervention program in a school environment and to pursue the investigation of the treatment effects with concomitant use of medications to surpass resistances to enroll patients and to have an assessment with more external validity.
126

Near-Infrared Spectroscopy neurofeedback (NIRS neurofeedback) em crianças com Transtorno de Déficit de Atenção/Hiperatividade (TDAH)

Londero, Igor January 2015 (has links)
As intervenções com neurofeedback têm tido grande difusão na área como uma alternativa possível para tratamento do Transtorno de Déficit de Atenção/Hiperatividade (TDAH). Este estudo tem o objetivo de avaliar a viabilidade da utilização de um sistema de neurofeedback de baixo custo chamado Near Infrared Spectroscopy/Hemoencephalography Neurofeedback (NIR/HEG-NF) para tratar crianças com TDAH. Método: trata-se de um estudo clínico piloto aberto, que incluiu 5 crianças (3 meninos e 2 meninas - idade 10,4 ± 0,89 anos) com TDAH-C (tipo combinado). Os indivíduos completaram um programa de 24 sessões de NIR/HEG-NF, duas ou três vezes por semana. Os seguintes desfechos foram avaliados pré e pós-tratamento: 1) sintomas de desatenção e hiperatividade; 2) desempenho neuropsicológico; 3) imagens de SPECT cerebral; 4) qualidade de vida; e 5) efeitos adversos. Resultados: houve maior resistência do que o esperado para a participação dos indivíduos devido a vários fatores, tais como logísticos para a participação nas sessões e requerimento de não uso de medicação durante o protocolo. Detectamos uma diferença significativa na comparação pré e pós-intervenção nos escores atribuídos pelos pais na dimensão de hiperatividade e impulsividade do Swanson, Nolan and Pelham Questionnaire (SNAP-IV) (p = .042; tamanho de efeito [ES] =.38) e uma tendência de melhora nos escores atribuídos pelos pais e professores na dimensão desatenção (p = .066; ES = .47 / p = .068; ES = .60) naquelas crianças que finalizaram o tratamento. Detectamos uma tendência de aumento perfusional em diferentes partes do córtex cerebral em três indivíduos. As comparações pré e pós-intervenção nas outras medidas não indicaram diferenças estatisticamente significativas. Não foram relatados efeitos adversos significativos. Discussão: Os achados iniciais sugerem que o NIR/HEG-NF como tratamento para sintomas de TDAH pode ser promissor e deve ser melhor investigado. O protocolo lança luz sobre novas abordagens para avaliar a eficácia da intervenção. Pode-se, por exemplo, implementar o programa de intervenção no ambiente escolar e com uso concomitante de medicamentos para superar as resistências na alocação de pacientes e para uma avaliação com maior validade externa. / Background and objectives: Neurofeedback interventions have been quick and extensively introduced for clinicians to treat Attention-Deficit/Hyperactivity Disorder (ADHD). This study aims to assess the feasibility of using a low cost neurofeedback system called Near Infrared Spectroscopy/ Hemoencephalography Neurofeedback (NIR/HEG-NF) for treating children with ADHD. Method: This open pilot clinical study included 5 children (3 boys and 2 girls - age 10.4 ± 0.89 years) with ADHD-C (combined type). The subjects completed a program of 24 sessions of NIR/HEG-NF, two or three times a week. The following outcomes were assessed pre and post-treatment: 1) clinical symptoms of inattention and hyperactivity; 2) neuropsychological performance; 3) brain SPECT images; 4) quality of life and; 5) adverse effects. Results: Higher resistance than expected was experienced for patient allocation due to logistic reasons to attend the sessions in the hospital and the requirement of not using medication during the protocol. We detected a significant decrease in hyperactivity/impulsivity comparing pre and post-intervention scores in the parent’s Swanson, Nolan and Pelham Questionnaire - SNAP-IV (p = .042; Effect Size [ES] r = .38) and a trend of improvement in scores attributed by parents and teachers in inattention (p = .066; r = .47 / p = .068; r = .68) . We detected a trend for increased perfusion in different parts of the entire cortex in 3 subjects. Comparisons between pre and post-intervention scores in other measures did not suggest meaningful differences. No significant adverse effects were reported. Discussion: Our initial findings suggest that NIR/HEG-NF technique might be promising and should be further investigated. The protocol shed light on new approaches to assess the effectiveness of the intervention such as the need to both implement the intervention program in a school environment and to pursue the investigation of the treatment effects with concomitant use of medications to surpass resistances to enroll patients and to have an assessment with more external validity.
127

Determinação de parametros de qualidade da gasolina e estudo de contaminantes utilizando espectros do infravermelho proximo na fase vapor

Sousa, Eliane Rodrigues de 12 February 2005 (has links)
Orientador: Jarbas Jose Rodrigues Rohwedder / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T16:07:01Z (GMT). No. of bitstreams: 1 Sousa_ElianeRodriguesde_D.pdf: 1575011 bytes, checksum: 32fcdf7815aa2854c92c4a91e1f22e17 (MD5) Previous issue date: 2005 / Doutorado / Quimica Analitica / Doutor em Quimica
128

Uso de espectroscopia funcional por infravermelho próximo na classificação de estados afetivos e desenvolvimento de um protocolo de neurofeedback para fins terapêuticos

Trambaiolli, Lucas Remoaldo January 2018 (has links)
Orientador: Prof. Dr. João Ricardo Sato / Coorientador: Prof. Dr. André Mascioli Cravo / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Neurociência e Cognição, São Bernardo do Campo, 2018.
129

Avaliação da qualidade do lenho de árvores de Eucalytpus geneticamente modificadas / Evaluation of wood quality of genetically modified Eucalyptus trees

Nayara Marcon Vire 29 July 2016 (has links)
Este estudo tem como objetivo analisar a qualidade do lenho das árvores de eucalipto geneticamente modificadas e seus respectivos controles (clones convencionais). Foram selecionadas 70 árvores de eucalipto, ao 12º mês de 14 tratamentos (10 eventos modificados e 4 clones convencionais) representando 5 árvores/tratamento. As amostras do lenho foram coletadas do tronco das árvores com sonda de Pressler para análise das suas características anatômicas, densidade aparente do lenho (microdensitometria dos raios X) e propriedades químicas (espectroscopia no infravermelho próximo). As propriedades anatômicas e a densidade aparente do lenho indicaram poucas diferenças significativas entre as árvores dos tratamentos. Nas análises da espectroscopia no infravermelho próximo (NIR) foram encontrados modelos satisfatórios para a densidade aparente do lenho, a fração parede e para o teor de celulose. O lenho das árvores dos eventos modificados e dos clones convencionais mostrou pequenas diferenças nas características anatômicas e físicas, sendo caracterizado como lenho juvenil; assim as árvores devem ser analisadas em idades mais avançadas, com lenho de transição e adulto. Os resultados constituem-se parte da análise das árvores de eucalipto geneticamente modificadas, subsidiando os estudos genéticos visando obter altos níveis de produtividade. / This study aims to analyze the quality of the wood of genetically modified eucalyptus trees and their respective controls (conventional clones). 70 eucalyptus trees were selected at 12 months of 14 treatments (10 modified events and 4 conventional clones) representing 5 trees / treatment. The wood samples were collected of the trunk of the eucalyptus trees with Pressler increment borer for the analysis of their anatomical features, density of wood (microdensitometry of X-rays) and chemical properties (near infrared spectroscopy). The anatomical properties and wood density of eucalypts trees showed few significant differences between treatments. In the analysis of near infrared spectroscopy (NIR) have been found satisfactory models for the apparent density of the wood, the wall portion and the cellulose content. The wood from the trees of the modified events and conventional clones showed small differences in the anatomical and physical characteristics, being characterized as juvenile wood; so the trees must be analyzed at older ages, with wood transition and adult. The results are a part of the analysis of genetically modified eucalyptus trees, supporting genetic studies to obtain high levels of productivity.
130

Caracterização do petróleo por técnicas espectroscópicas e sua utilização na avaliação e desenvolvimento de métodos de inferência em processo de refino. / Characterization of petroleum by spectroscopic techniques and their use in the evaluation and development of inference methods for the refining process.

Patricia Araujo Pantoja 26 November 2010 (has links)
A classificação e caracterização do petróleo cru em tempo real é um dos mais importantes desafios atuais da indústria petroquímica e agencias ambientais. Um método rápido e econômico antes da destilação do petróleo iria a fornecer informações químicas de grande importância para o ajuste em tempo real dos parâmetros críticos de uma refinaria, permitindo a otimização do processo, resultando em benefícios econômicos e ambientais. Uma variedade de técnicas espectroscópicas está sendo utilizadas nas ultima décadas para as analises, classificação e caracterização de petróleo cru nos campos de perfuração, para as análises dos produtos petrolíferos e para detecção de derrames. As vantagens do uso desta técnica incluem uma rápida resposta, requerimento mínimo de preparação da amostra e equipamentos relativamente econômicos. As técnicas espectroscópicas envolvidas na tese (NIR) mostraram o maior potencial no campo. No entanto, os estudos realizados com todas estas técnicas não foram enfocados em aplicações em linha. O NIR é tradicionalmente a técnica espectroscópica mais utilizada para a análise de petróleo cru. Mas os problemas típicos que esta técnica apresenta são sobreposição das diferentes bandas de absorção e saturação do sinal devido à alta absorbância característico do petróleo cru. A Fluorescência é um fenômeno mais complexo do que a absorção (NIR) e efeitos como quenchinge transferência de energia têm que ser consideradas. No entanto, a espectroscopia de fluorescência pode fornecer sinais bidimensionais com muito mais informação do que uma emissão unidimensional do espectro de absorção. Enquanto a espectrometria de massa, a técnica MALDI TOF faz possível a ionização de macromoléculas que são difíceis de serem ionizadas por não ser facilmente decompostas. Neste trabalho, as vantagens e limitações das técnicas disponíveis são analisadas e o potencial do analises remoto em linha do petróleo cru é avaliado. A pesar da boa analise e classificação obtida com algumas técnicas, nem sempre é possível integrá-los em um sistema em linha quando uma preparação previa da amostra é necessária ou quando o sistema é demasiado complexo. Para a extração da informação química contida nos espectros foram utilizados métodos matemáticos e estatísticos (quimiométricos) nos espectros: Mínimos Quadrados Parciais (PLS). / Online remote characterization and real-time classification of crude petroleum is one of the most important current challenges faced by the petrochemical industry and environmental agencies. A rapid and inexpensive method for the remote analysis and classification of petroleum prior to distillation of the crude would provide chemical information of great importance for real time adjustment of the critical parameters of a refinery, permitting an optimization of the process and resulting in economic and environmental benefits. A variety of spectroscopic techniques have been used over the last few decades for the analysis, characterization and classification of crude oil in drilling fields, for the analysis of petroleum products and for the detection of oil-spills. The advantages of using these techniques include rapid response, the requirement of minimal sample preparation and relatively inexpensive equipment costs. The spectroscopic techniques involved in the thesis (NIR, fluorescence and mass spectrometry) showed the greatest potential in the field. Nevertheless, the studies carried out with these techniques typically do not focus on online applications. NIR is traditionally the spectroscopic techniques most used for crude petroleum analysis. Overlap of the different absorption bands and saturation of the signal due to the high absorbance of crude petroleum are typical problems encountered with this technique. Fluorescence is a more complex phenomenon than absorption (NIR) and effects such as quenching and energy transfer have to be considered. However, fluorescence spectroscopy can provide two-dimensional signals with much more information than a one-dimensional emission or absorption spectrum. While mass spectrometry, MALDI TOF technique makes possible the ionization of macromolecules that are difficult to be ionized not be easily broken. In this work, the advantages and limitations of the available techniques are analyzed and the potential for remote on-line analysis of crude petroleum is evaluated. In spite of the good analysis and classification obtained with some of the techniques, it is not always possible to integrate them into a remote on-line analytical system when some prior sample preparation is required or when the system is too complex. For the extraction of chemical information contained in the spectra were used mathematical and statistical (chemometric) in the spectra: Partial Least Squares (PLS).

Page generated in 0.0709 seconds