Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2009. / Triticale (X Triticosecale Whittmack), a cross between durum wheat (Triticum sp.) and rye, is a crop with an increasing agronomic and economic potential Though studies on the functional and compositional quality of triticale have been conducted in other parts of the world, little is known regarding cultivars developed in South Africa in terms of these aspects. South African triticale cultivars from various localities in the Western Cape, obtained for two subsequent harvest seasons, were analysed for moisture, protein and ash contents, as well as falling number (an indication of α-amylase activity), hardness (particle size index), 1000-kernel mass and baking potential (SDS sedimentation). These triticale samples were derived from a breeding program that was not focused on baking quality. The results obtained were found to compare well with those reported on in previous studies. Significant differences were observed between both cultivars and localities within years, illustrating the effect of genetic as well as environmental factors. Significant differences were also observed between localities when comparing the two harvest seasons, whereas differences between the cultivars for the two seasons were in most cases not significant; illustrating the effect of environment. Interactions between cultivars and localities were found to be significant for all parameters, and trends were observed between protein content and both particle size index (PSI) (negative) as well as SDS sedimentation (positive) results for both years. Near infrared (NIR) spectroscopy is a rapid method of analysis and is widely used for the quality evaluation of wheat. Limited research has been reported on calibration models for the quality evaluation of triticale, and thus NIR spectroscopy was applied to develop models for the prediction of moisture, protein and ash contents, as well as hardness and baking potential for South African cultivars. Spectra were collected in diffuse reflectance mode and partial least squares (PLS) models developed for both triticale flour and wholegrain using two different instruments (Büchi NIRFlex N-500 and Bruker MPA Fourier transform NIR spectrophometers) and software packages (The Unscrambler and OPUS). Full cross-validations were performed, after which the best prediction models obtained (R2 > 0.66) were validated using an independent test set (n = 50). The best prediction results were obtained with flour for moisture (Bruker: SEP = 0.08%; R2 = 0.95; RPD = 4.65) and protein (Büchi: SEP = 0.44%; R2 = 0.96; RPD = 5.23 and Bruker: SEP = 0.32%; R2 = 0.96; RPD = 4.88). For whole grain, acceptable results were obtained for protein (Büchi: SEP = 0.55%; R2 = 0.94; RPD = 4.18 and Bruker: SEP = 0.70%; R2 = 0.90; RPD = 3.23). Though results for ash content, PSI and SDS sedimentation prediction did not yield models that can be applied as yet, these models form a good basis for further calibration model development and possibly use in early generation screening. The current limited ranges could be expanded by adding samples from subsequent harvest seasons. By adding more data, a better quality profile for South African triticale can be obtained, which will facilitate better interpretation in terms of the effect of genetic and environmental factors. It would also enable the development of improved NIR prediction models.

Thesis (MSc Food Sc )--Stellenbosch University, 2003. / ENGLISH ABSTRACT: This study shows the potential of near infrared spectroscopy for both qualitative and quantitative analyses of wine and brandy in the distilling industry. Wines intended for further processing by the distillation industry have to meet certain specifications to ensure an efficient and cost-effective distilling process with a suitable product yield. Certain compounds have, therefore, been recognised as significant quality parameters and through their regulation, a product of consistent quality can be ensured. These quality parameters include alcohol, total acid, volatile acid, total sulphur dioxide, total phenolics, reducing sugars and acetaldehyde concentrations and pH. The effective control of all these compounds in the wines prior to distillation, is critical to maintain the feasibility and efficiency of the process. Fourier transform near infrared spectroscopy (FT-NIRS) can be used as a rapid and accurate analytical method for the determination of alcohol concentrations in distilling and brandy base wine. The choice of path length for the liquid sampling cell is an important consideration. In this study, alcohol with its strong absorption of OH bands in the near infrared region was not significantly affected, but difference in path length showed a significant influence on the prediction of the volatile acid concentration in distilling wine. Very strong correlations were found between the spectral data and the alcohol concentration data in distilling wine (r = 0.99, SEP = 0.18% v/v, RER =30) and brandy base wine (r = 0.92, SEP = 0.18% v/v, RER = 11.1). Good predictions were obtained for the volatile acid content of brandy base wine (r = 0.85, SEP = 0.04 g.L-1 ) but better accuracy could be obtained by incorporating a wider concentration range and more sensitive, although not the accepted reference methods, such as HPLC and GC, into the modelling. In contrast to the brandy base wine, the much cruder, turbid distilling wine (r = 0.67, SEP = 0.33 g.L-1 ) yielded poor calibration results for volatile acid. FT-NIRS can also be used as a rapid screening method to measure the total acid content, pH and total phenol levels in brandy base wine samples. Satisfactory predictions were obtained for the total acid content (r = 0.89, SECV = 0.38 g.L-1 ), pH (r = 0.84, SEP = 0.09) and total phenol levels (r = 0.71, SEP = 16.4 mq.L" GAE). The SEP of all the parameters compared well with the SEL and were within acceptable limits. The range of the concentration measurements were, however, very narrow and the accuracy of these models (measured as the ratio of the range to the standard error of prediction) were all below 10, indicating that modelling of these parameters in brandy base wine should be attempted with reference values covering a wider range. Poor correlations and predictions were obtained between the wine spectral data and the acetaldehyde (r = 0.39 , SECV =1.45 rnq.L"), residual sugar (r = 0.58, SECV =0.49 mq.L" ) and total sulphur dioxide (r = 0.35, SEP = 10.9 mq.L" ) concentration data. The unique character of potstill distillates, originating from the grape cultivar, type and age of the oak casks, lends itself to the development and blending of different brandies. The process of blending and correcting the brandy is necessary to obtain a product and brand of established and recognised character. The brandy is generally divided into different classes prior to blending based on the degree of "smoothness" or "hardness" of the matured distillate as determined by a sensorial panel. The ideal would, however, be to replace this subjective evaluation method with a more objective approach, such as an instrumental method like NIRS. Near infrared spectroscopy showed potential to successfully discriminate and classify brandy samples in terms of their sensorial classification status. The near infrared spectra of unblended three-year old brandies were measured and discriminant analysis performed using the subjective sensory classification data of the brandy. SIMCA (soft independent modelling of class analogy) models were developed by calculating separate peA (principal component analysis) models for each of the classes for which qualitative analysis were required. An assessment of class membership of an unknown sample was made on the basis of the distance to the cluster centroid. Two types of NIRS instruments, a Fourier transform near infrared system and a diode array spectrophotometer were employed to examine the discriminatory abilities of NIRS. Excellent predictions (90.9%-100%) were obtained for the "smoothest" and "hardest" classes within the 2000 and 2001 seasons with FT-NIRS. For the diode array spectra reasonable classification data were obtained for all the classes within the 2000 and 2001 seasons, as well as an excellent classification rate (100%) of the smoothest class in the 1999 season. Prediction results for class membership of the brandy samples from the three season's combined data did not deliver satisfactory discriminatory results. By applying NIRS and SIMCA, rapid and objective classification of brandy samples within seasonal context can be established to enhance the blending processes. Having accurate reference data in the calibration set is essential in near infrared spectroscopy (NIRS). The precision (usually decided by blind duplicate determination) of the reference data serves as the performance target for correlation-based near infrared analysis. The differences between reference values obtained from two independent laboratories and the Foss Winescan FT 120, which is also a predictive method, for the alcohol and volatile acid determinations in distilling wine and between two independent laboratories for the measurement of the total sulphur dioxide content, were investigated. ANOVA and post-hoc analysis (Bonferroni testing) revealed statistically significant differences (p<O.OS)between all three measurements for the volatile acid analysis. One laboratory differed significantly from the other two measurements in its measurement of the alcohol content in distilling wine. A paired t-test performed on the two laboratories' values obtained for total sulphur dioxide revealed statistically significant differences (p<O.OS) between the two sets of results. This study restated the importance of obtaining reliable reference data for calibration purposes to maintain the efficiency and accuracy and therefore the reputability of NIRS as an accurate and reliable analytical method. / AFRIKAANSE OPSOMMING: Hierdie studie dui op die potensiaal van naby infrarooi spektroskopie (NIRS) vir beide die kwalitatiewe en kwantitatiewe analise van wyn en brandewyn in die distillasie industrie. Sekere spesifikasies word gestel waaraan wyn met voldoen voor dit verdere prosessering tydens distillasie kan ondergaan. Die regulering van wynkwaliteit is noodsaaklik om die distilleringsproses ekonomies volhoubaar te maak. Sekere komponente in die wyn het 'n direkte invloed op die kwaliteit van die eindproduk en word beskou as betekenisvolle parameters wat beheer moet word om 'n produk van konstante hoë kwaliteit te lewer. Hierdie parameters sluit alkohol, titreerbare suur- en vlugtige suurinhoud, asook die pH, totale swaweidioksied, totale fenol vlakke, reduserende suikers en asetaldehied konsentrasies in. Die regulering van al hierdie komponente in die wyne is essensieel voor die aanvang van distillasie om die effektiwiteit en produktiwiteit van die proses te verseker. Fourier transformasie naby-infrarooi spektroskopie (FT-NIRS) kan benut word as 'n vinnige en akkurate analitiese metode om die alkohol konsentrasie in stook- en rabatwyn te bepaal. 'n Geskikte padlengte kuvet moet gekies word vir die ontleding van vloeistof monsters met NIRS. In hierdie studie is gevind dat die voorspelling van alkoholkonsentrasie in wyn, nie soseer beïnvloed is deur die keuse van padlengte nie. 'n Vlugtige komponent soos asynsuur, wat die maatstaf van die vlugtige suurinhoud van die wyn is, word egter regstreeks beïnvloed deur die keuse van padlengte. 'n Sterk korrelasie is gevind in die datastel vir die alkoholinhoud van die stookwyn (r = 0.99, SEP = 0.18% v/v, RER = 30) en rabatwyn (r = 0.92, SECV = 0.18% v/v, RER = 11.1). Baie goeie voorspellings is ook gevind vir die vlugtige suurinhoud van rabatwyn (r = 0.85, SEP = 0.04 g.L-1). Die akkuraatheid van die metode (uitgedruk as die RER waarde) het egter aangedui dat 'n wyer konsentrasie omvang en meer akkurate verwysingswaardes gebruik moet word om 'n geskikte model vir vlugtige suur kwantifikasie in rabatwyn te bewerkstellig. In teenstelling met die resultate verkry vir die rabatwyn, het die ruwer, turbiede stookwyn swak gekalibreer vir die vlugtige suurinhoud (r = 0.67, SEP = 0.33 g.L-1 ). FT-NIRS kan ook gebruik word as 'n vinnige seleksie metode om titreerbare suur vlakke, pH en totale fenolinhoud van rabatwyn monsters te bepaal. Sterk korrelasies is in die datastel gevind vir die titreerbare suurinhoud (r = 0.89, SECV = 0.38 g.L-1 ), pH (r = 0.84, SEP = 0.09) en totale fenol vlakke (r = 0.71, SEP = 16.4 rnq.L" GAE) van rabatwyn. Die SEP waardes verkry vanaf die NIRS bepalings het baie goed vergelyk met die standaard foute wat verkry is vir die chemiese bepalings. Die konsentrasie omvang van die verwysingswaardes was, egter, beperk en die akkuraatheid van die NIRS modelle (uitgedruk as die verhouding tussen die konsentrasie omvang en die standaard fout van voorspelling) was laer as 10. Dit het daarop gedui dat die NIRS kalibrasie van die parameters eerder uitgevoer moet word met monsters wat 'n wyer konsentrasie omvang dek en gemeet is met meer sensitiewe analitiese metodes soos HPLC en GC. Die kalibrasie en voorspelling van die asetaldehied inhoud (r = 0.39 , SECV =1.45 rnq.L"), reduserende suiker konsentrasie (r = 0.58, SECV =0.49 mq.L" ) en totale swaweldioksiedinhoud (r = 0.35, SEP = 10.9 rnq.L" ) het onaanvaarbare voorspellings gelewer. Die unieke karakter van potketel distillate wat bepaal word deur die druifkultivar, tipe en ouderdom van die eikehoutvate, bied die potensiaal vir die ontwikkeling en versnyding van verskillende style brandewyn. In 'n poging om 'n produk en handelsnaam van erkende en gevestigde karakter te verkry, moet die brandewyn eers versny word na veroudering. Die brandewyn word geklassifiseer in verskillende style op grond van sensoriese gehalte. NIRS is gebruik as 'n vinnige tegniek om te onderskei tussen verskillende style onversnyde drie jaar-oue brandewyn. SIMCA (soft independent modelling of class analogy) modelle is ontwerp deur aparte PCA (hoof komponent analise) modelle vir elke klas waarvoor kwalitatiewe analise vereis is, te ontwikkel. 'n Skating van klas lidmaatskap van 'n onbekende monster is gemaak deur die afstand van die monster na die groepsmiddelpunt te bereken. Twee soorte NIRS instrumente, 'n FT-NIR en 'n diode array spektrofotometer is gebruik tydens die studie om die diskrimineringsvermoë van elk te ondersoek. Uitstekende voorspellings (90.9%-100%) is gekry vir die "sagste" en "hardste" klasse binne die 2000 en 2001 seisoene met FTStellenbosch NIRS. Met die diode array spektra is redelike klassifikasie resultate verkry vir al die klasse binne die 2000 en 2001 seisoene, asook 'n uitstekende klassifikasie (100%) vir die sagste klas binne die 1999 seisoen. Voorspellings vir klas lidmaatskap van die brandewyn monsters vir die drie seisoene se gekombineerde data het egter onaanvaarbare diskriminasie resultate gelewer. NIRS en SIMCA sal 'n vinnige en objektiewe klassifikasie proses van onversnyde brandewyn monsters kan meebring wat tot voordeel van die versnydings- en produksieproses sal wees. Hierdie voorspellings sal egter binne seisoensverband moet geskied. Akkurate verwysingsdata in die kalibrasie datastel is 'n essensiële fasset van naby infrarooi spektroskopie. Die presisie (bepaal deur blinde duplikaat bepalngs) van die verwysingsdata dien as 'n prestasie teiken vir korrelasie-gebaseerde naby infrarooi voorspellings. Die verskille tussen die data verkry vir die alkohol- en vlugtige suurinhoud van stookwyn deur twee onafhanklike laboratoriums en 'n instrumentele metode (Foss Winescan FT 120) asook die verskille tussen die data verkry van twee laboratoriums vir die totale swaweidioksied metings, is ondersoek. ANOVA en post-hoc toetse het aangedui dat al die data verkry vir die vlugtige suur bepalings, statisties betekenisvol van mekaar verskil het (p<0.05). Vir die alkohol bepalings in stookwyn, het die data verkry van een laboratorium betekensvol verskil van die ander twee datastelle. Gepaarde t-toetse uitgevoer op die data verkry vir totale swaweldioksiedinhoud, het ook betekinisvolle verskille aangedui tussen die twee laboratoriums. Hierdie studie het die belangrikheid van betroubare verwysingsdata vir kalibrasie doeleindes beklemtoon, veral waar 'n tegniek soos NIRS se werksverrigting afhang van die akkuraatheid van dié waardes.

Thesis (MSc Food Sc )--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The effect of drying conditions on the retention of harpagoside, a glucoside iridoid found in the indigenous Southern African plant Harpagophytum procumbens (Devil's Claw), was investigated. Additionally, the feasibility of using near infrared spectroscopy (NIRS) as a rapid and nondestructive analytical tool for the prediction of the iridoids harpagoside (HS), 8-p-coumaroyl harpagide (8pCHG) and moisture contents, as well as the HS:8pCHG ratio in Devil's Claw was also studied. Due to the purported medicinal activity ofthe tuberous secondary roots, Devil's Claw is of commercial interest with a well established export market in Germany. The stability of HS during processing has, however, never been investigated and the current study evaluated the effect of three drying methods (sun, tunnel and freeze-drying), as well as three tunnel-drying temperatures (40°C, 50°C and 60°C, dry bulb temperature) on HS content. Methanolic extracts (70% methanol-water) were analysed by high-performance liquid chromatography (HPLC) and a multiple extraction test (n = 12) indicated a 91.70% recovery for HS. The comparative drying results showed significant (P < 0.05) differences between tunnel and freeze drying on the one hand and sun-drying on the other, with the latter being the most detrimental technique. In comparing tunnel-drying temperatures, at a constant relative humidity (RH) of30%, drying at 40°C showed the lowest retention ofHS, differing significantly (P < 0.05) from that at 50°C. Drying at 60°C did not differ significantly (P > 0.05) from either of the other two conditions, but also resulted in lower retentions ofHS content than drying at 50°C. Overall, freeze-drying showed excellent results for HS retention (1.565% ± 0.394%; mean ± standard deviation), but economic constraints limit the commercial application of this drying method. Although further study is required to optimise tunnel-drying conditions, this method indicated acceptable and practical results (1.526% ± 0.396%), especially with conditions set to 50°C and 30% RH (1.750% ± 0.438%). Future research should concentrate on elucidating the degradation mechanisms of HS during processing, transport and storage of dried Devil's Claw root. The analysis of dried, ground Devil's Claw root by NIRS was referenced to HPLC analyses of the same methanolic extracts used in the drying studies. The spectra were generated on two different NIRS instruments by measuring diffuse reflectance of the powder whilst calibrations were performed by partial least squares regression. Both independent data set validation and full cross-validation were used to evaluate the performance and predictive abilities of the various models. Excellent moisture content (MC) calibrations were developed with a standard error of prediction (SEP) ofO.24% (range: 2.44% to 10.43%) and correlation coefficient (r) of 0.99. For the given MC range, the model performed very well against the standard error of laboratory (SEL) ofO.14%. Considering the sensitivity of the HPLC reference method (SEL = 0.035%), the HS content calibration (range: 0.693% to 2.244%) performed admirably with an SEP ofO.134%. The available range was, however, relatively small and future NIRS studies should incorporate a larger range if possible. The 8pCHG model (range: 0.069% to 0.290%) performed similarly, with a standard error of cross-validation of 0.028% and SEL of 0.007%. By inclusion of a second species, H. zeyheri, both the 8pCHG content and especially HS:8pCHG ratio (range: 1.84 to 34.48) calibrations were evaluated as possible methods of distinguishing between species. With 8pCHG values of ca. 0.9%, good separation was achieved for the first model but, contrary to previous studies, the ratio was found to be less successful. Principle component analysis of the spectra, however, showed great potential as a qualitative tool for this purpose. It is believed that NIRS can become an invaluable tool for the division of Devil's Claw into export classes, depending on HS content. This content is, however, dependant on the drying conditions used and drying parameters should be optimised to ensure the best possible quality and retention ofHS. / AFRIKAANSE OPSOMMING: Die invloed van drogingskondisies op die behoud van harpagosied, 'n iridoïed glikosied wat in die inheemse Suider-Afrikaanse plant, Harpagophytum procumbens (Duiwelsklou) voorkom, is ondersoek. Die uitvoerbaarheid van naby infra-rooi spektroskopie (NIRS) as 'n vinnige en niedestruktiewe analitiese metode vir die voorspelling van die inhoud van iridoïede, harpagosied (HS), 8-p-kumaroïel-harpagied (8pCHG) en vog, sowel as die HS:8pCHG verhouding in Duiwelsklou is ook ondersoek. Die beweerde medisinale aktiwiteit van die knolagtige sekondêre wortels van Duiwelsklou het gelei tot 'n gevestigde uitvoermark in Duitsland, en is dus van kommersiële belang. Die stabiliteit van HS gedurende prosessering is nog nooit ondersoek nie. Die huidige studie het die invloed van drie drogingsmetodes (son-, tonnel- en vriesdroging) en drie tonneldrogingstemperature (40°C, 50°C en 60°C, droëbol temperatuur) op die HS inhoud evalueer. Metanolies ekstrakte (70% metanol-water) is met hoë-druk vloeistof chromatografie ("HPLC") geanaliseer en 'n veelvoudige ekstraksie toets (n =12) het 'n 91.70% herwinning van HS getoon. Betekenisvolle (P < 0.05) verskille is gevind tussen tonnel- en vriesdroging enersyds en sondroging andersyds, met laasgenoemde die nadeligste metode. Die vergelyking van tonneldrogingstemperature, by 'n konstante relatiewe humiditeit (RH) van 30%, het getoon dat droging by 40°C die minste HS behou het en betekenisvol (P < 0.05) verskil het van droging by 50°C. Alhoewel die droging by 60°C nie betekenisvol verskil het van die ander twee kondisies nie, het dit laer HS waardes as droging by 50°C getoon. Vriesdroging het uitstekende resultate ten opsigte van die behoud van HS gelewer (1.565% ± 0.394%; gemiddelde ± standaard afwyking), maar ekonomiese beperkings plaas noodgedwonge limiete op die toepaslikheid van hierdie drogingsmetode. Verdere studie om tonneldrogingskondisies te optimiseer word is nodig (1.526% ± 0.396%), maar veral droging by 50°C en 30% RH (1.750% ± 0.438%) het prakties aanvaarbare resultate gelewer. Toekomstige navorsing moet daarop gemik word om die spesifieke degradasie meganismes van HS gedurende die droging, vervoer en opberging van Duiwelsklouwortel te verklaar. Die NIRS ontleding van gedroogde, gemaalde Duiwelsklou wortel is vergelyk met HPLC analises van dieselfde metanolise ekstrakte wat tydens die drogingstudies gebruik is. Twee verskillende NIRS instrumente is gebruik om spektra deur diffuse weerkaatsing in die poeier te meet en kalibrasies is daaropvolgend met gedeeltelike minste vierkante ("PLS") regressie gedoen. Beide onafhanklike data stel validasie en volle kruisvalidasie is gebruik om die prestasie en voorspellingsvermoë van die onderskeie modelle te evalueer. Uitstekende voginhoud (VI) kalibrasies met 'n standaard voorspellings fout (SVF) van 0.24% (klasinterval: 2.44% tot 10.43%) en 'n korrelasie van 0.99 is gevind. Die model het goed vergelyk met die standaard laboratorium fout (SLF) van 0.14%, oor die gegewe klasinterval. Met inagneming van die sensitiwiteit van HDVC as verwysingsmetode (SLF = 0.035%), het die HS inhoud kalibrasie (klasinterval: 0.693% tot 2.244%) aanvaarbaar gepresteer met 'n SVF van 0.134%. Die beskikbare klasinterval was egter relatief klein en toekomstige NIRS studies moet gebruik maak van 'n wyer klasinterval indien moontlik. Die 8pCHG model (klasinterval: 0.069% tot 0.290%) het soortgelyk gepresteer, met 'n standaard kruisvalidasie fout van 0.028% en SLF van 0.007%. Met die insluiting van monsters van 'n tweede spesie, H. zeyheri, is beide die 8pCHG inhoud en HS:8pCHG verhouding (klasinterval: 1.84 tot 34.48) kalibrasies as moontlike metodes vir onderskeiding tussen die spesies geëvalueer. Met'n 8pCHG inhoud van ca. 0.9% het die eerste model 'n goeie skeidingsvermoë getoon. In teenstelling met vorige studies egter, het die verhoudingsmodel minder sukses getoon. Hoofkomponent analise ("PCA") van die spektra was egter baie belowend as 'n kwalitatiewe onderskeidingsmetode. Volgens hierdie studie kan NIRS 'n waardevolle tegniek wees vir die verdeling van Duiwelsklou in uitvoer klasse op grond van HS inhoud. Hierdie inhoud is egter grotendeels afhanklik van die drogingskondisies en drogingsparameters wat verder verfyn behoort te word om 'n produk van die hoogste kwaliteit met behoud van HS te verseker.

Thesis (MSc Food Sc)--University of Stellenbosch, 2011. / Please refer to full text to view abstract.

CASTRO JUNIOR, Manoel Carvalho. Transições de fase em perovskitas politípicas. 2013. 153 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2013. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-29T18:31:41Z No. of bitstreams: 1 2013_tese_mccastrojunior.pdf: 7600147 bytes, checksum: e5ee8745b29672a07d4666c3a0c48753 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-11-03T19:46:16Z (GMT) No. of bitstreams: 1 2013_tese_mccastrojunior.pdf: 7600147 bytes, checksum: e5ee8745b29672a07d4666c3a0c48753 (MD5) / Made available in DSpace on 2015-11-03T19:46:16Z (GMT). No. of bitstreams: 1 2013_tese_mccastrojunior.pdf: 7600147 bytes, checksum: e5ee8745b29672a07d4666c3a0c48753 (MD5) Previous issue date: 2013 / In this thesis, vibrational spectroscopy was used to investigate the structural transitions of polytypic perovskites. Representative compounds of two polytypes were studied: the multiferroic 3C-type perovskite Pb(Fe1/2Nb1/2)O3 (PFN) and the 6H-type perovskites Ba3B2+Sb2O9 (B = Mg, Ca e Sr). Based on anomalies or deviations from normal behavior of the adjustable parameters of the temperature dependence of the phonon spectra of these compounds, it was possible to identify structural transformations. In PFN, it was observed, evidences of two transitions between ferroelectric phases, in addition to a transition between different magnetic ordering states (paramagnetic → antiferromagnetic) and different polar states (paraelectric → ferroelectric). These results provide stronger evidences than previous Raman Spectroscopy reports in literature due to a better resolution, which allowed us to observe, for example, a new phonon at the Néel temperature. In the case of the 6H perovskites, besides to the usual observation of temperature dependence of the phonon spectra, which provides evidences of the transition of a hexagonal to monoclinic phase at 140 K in the Ba3MgSb2O9 (BMS) and of a monoclinic to triclinic phase at 240 K in the Ba3MgSb2O9 (BCS), we classify the phonons of the three compounds using two methods. First we applied the Hartree-Fock ab-initio method to calculate the normal modes of the Sb2O9 dimer; and assuming that the unit cell of BMS is constituted of Sb2O9 dimers and isolated ions of Ba and Mg, we correlate, using group theory methods, the calculated modes of Sb2O9 with the internal modes of BMS. Later we used the FG Wilson method to confirm the previous results, being obtained a good agreement between the two methods. / Nesta tese a espectroscopia vibracional foi empregada para investigar as transições estruturais de perovskitas politípicas. Compostos representativos de dois polítipos foram estudados: a perovskita multiferróica tipo 3C Pb(Fe1/2Nb1/2)O3 (PFN) e as perovskitas tipo 6H Ba3B2+Sb2O9 (B = Mg, Ca e Sr). A partir de anomalias ou desvios do comportamento normal dos parâmetros ajustáveis com a temperatura do espectro de fônons destes compostos foram identificadas transformações estruturais. No PFN foram observados indícios de duas transições entre fases ferroelétricas, além de uma transição entre diferentes fases de ordenamento magnético (estado paramagnético → estado antiferromagnético) e uma transição entre um estado paraelétrico e um ferroelétrico. Estes resultados são expostos de forma bem mais clara do que em trabalhos de espectroscopia Raman anteriormente informados na literatura, devido a melhor resolução obtida, o que propiciou até a observação da origem de um novo modo no entorno da temperatura de Néel. Nas perovskitas 6H, além da observação usual do comportamento dos fônons em função da temperatura, o que rendeu a observação da transição de uma fase hexagonal para uma fase monoclínica em 140K no Ba3MgSb2O9 (BMS) e de uma fase monoclínica para uma fase triclínica em 240 K no Ba3MgSb2O9 (BCS), procurou-se classificar os fônons dos três compostos utilizando dois métodos computacionais. Primeiramente utilizou- se o método ab initio de Hartree-Fock para calcular os modos normais do dímero Sb2O9; e assumindo que a célula unitária do BMS é formada de dímeros Sb2O9 e íons isolados de Ba e Mg, conseguiu-se correlacionar, utilizando teoria de grupos, os modos calculados do Sb2O9 com os modos internos do BMS. Posteriormente utilizou-se o método FG de Wilson para corroborar os resultados anteriormente obtidos, sendo observado um bom acordo entre ambos métodos.

Neste trabalho, foram estudadas estratégias para caracterização de bebidas à base de soja (BBS), por meio de análises por espectroscopia no infravermelho médio com transformada de Fourier com acessório de reflexão total atenuada (FTIR-ATR). Foram utilizadas 20 amostras comerciais de BBS, de 7 diferentes sabores e 3 diferentes marcas. Os teores estudados nas BBS foram glicídios totais, glicídios redutores, glicídios não redutores, e proteínas totais. Os modelos de regressão multivariada foram construídos por mínimos quadrados parciais (PLS), empregando como seleção de variáveis os métodos de mínimos quadrados parciais por intervalo (iPLS) e mínimos quadrados parciais por sinergismo de intervalos (siPLS). As seleções de variáveis por siPLS apresentaram os melhores resultados para os modelos construídos. Entre as propriedades avaliadas, a de glicídios totais apresentou modelos com erros de calibração e previsão (RMSECV e RMSEP) baixos, e coeficientes de determinação (R2cv e R2prev) próximos de um. Para proteínas totais, os modelos apresentaram resultados promissores, pois também tiveram erros de calibração e previsão (RMSECV e RMSEP) baixos, e coeficientes de determinação (R2cv e R2prev) próximos de um, considerando-se que as amostras reais e não apresentavam uma variabilidade de concentração de proteínas ideal. Para as propriedades de glicídios redutores e glicídios não redutores, não foram obtidos bons resultados para os modelos de regressão. Desta forma, a metodologia proposta apresenta potencial em análises de rotinas para determinação simultânea de glicídios totais e proteínas, atendendo aos requisitos referente às informações nutricionais na rotulagem das BBS, somando-se às vantagens da espectroscopia no infravermelho, tais como rapidez na análise, elevada frequência analítica, pequena quantidade de amostra necessária, baixo custo, não ser destrutiva e ser ambientalmente amigável. / In this work, strategies were studied for the characterization of soy-based beverages (SBB), by means of Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR). Twenty commercial samples of SBB were used, of 7 different flavors and 7 different brands. The contents studied in SBB were total sugar, reducing sugar, non-reducing sugars, and total proteins. The multivariate regression models were constructed by partial least squares (PLS), with evaluation of the methods by interval partial least squares (iPLS) and by sinergy interval partial least squares (siPLS), for selection of variables. The selections of variables per siPLS presented the best results for the constructed models. Among the evaluated properties, the total sugar content presented models with low calibration and prediction errors (RMSECV and RMSEP), and determination coefficients (R2cv and R2prev) close to one. For total proteins, the models presented promising results, as they also had low calibration and prediction errors (RMSECV and RMSEP), and determination coefficients (R2cv and R2prev) close to one, considering that the actual samples did not present an ideal protein concentration variability. For the properties of reducing sugars and non-reducing sugars, good results were not obtained for the regression models. In this way, the proposed methodology presents potential in routine analysis for simultaneous determination of total glycogen and protein, taking into account the requirements referring to the nutritional information in the SBB labeling, adding to the advantages of the infrared spectroscopy, such as speed in the analysis, high analytical frequency, small amount of sample required, low cost, non destructive and environmentally friendly.

Submitted by Morgana Andrade (morgana.andrade@ufes.br) on 2016-04-20T21:56:32Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) tese_7529_Lindamara Maria de Souza20140630-82317.pdf: 3532286 bytes, checksum: 2c24c77fad763f25826fe7fa50a73f20 (MD5) / Approved for entry into archive by Patricia Barros (patricia.barros@ufes.br) on 2016-04-27T12:36:39Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) tese_7529_Lindamara Maria de Souza20140630-82317.pdf: 3532286 bytes, checksum: 2c24c77fad763f25826fe7fa50a73f20 (MD5) / Made available in DSpace on 2016-04-27T12:36:39Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) tese_7529_Lindamara Maria de Souza20140630-82317.pdf: 3532286 bytes, checksum: 2c24c77fad763f25826fe7fa50a73f20 (MD5) / CAPES / A cocaína é uma droga estimulante do Sistema Nervoso Central (SNC) e um potente anestésico local. A duração de seus efeitos depende da forma consumida (sal, principalmente o cloridrato de cocaína, ou de base, de base livre ou crack) e no modo de administração (injetando, aspiração ou o fumo). A cocaína é definida como um alcaloide tropânico por apresentar em sua estrutura o núcleo tropano. Entretanto, apesar de sua composição definida, com a finalidade de diluir e aumentar o volume final da droga, o mercado ilícito se utiliza de uma grande diversidade de aditivos químicos como benzocaína, lidocaína, cafeína, procaína, entre outros. Esta dissertação foi dividida em três capítulos destinados a: i) avaliar o teste colorimétrico, ou seja, o teste de Scott, usando a espectroscopia de infravermelho com transformada de Fourier utilizando acessório de reflexão total atenuada (ATR-FTIR). Dezessete aditivos químicos foram avaliados, onde quatro forneceram resultados falsos positivos (prometazina, lidocaína, leite em pó e fermento). Quando o teste de Scott é realizado e aliado a técnicas espectroscópicas como ATR-FTIR e quimiometria, resultados conclusivos são obtidos e podem ser usados à rotina de laboratórios forenses. ii) Foi estudado o perfil químico orgânico de amostras de cocaína apreendidas no ano de 2012 nos meses de janeiro a julho usando a cromatografia gasosa acoplada a um espectrometro de massas quadrupolar (GC-MS). Neste capítulo, 101 amostras foram analizadas no modo full scan e 83 destas usadas para construção de um modelo quimiométrico usando a análise de componentes principais (PCA). Os principais adulterantes encontrados foram lidocaína, fenacetina e cafeína. Adicionalmente, cocaína, lidocaína e cafeína foram quantificadas a partir do monitoramento do íon selecionado (SIM) e seus valores de linearidade, limites de detecção e quantificação determinados. iii) as amostras de cocaína apreendidas pela polícia civil foram classificadas em função do tempo (2008, 2009, 2010, 2011 e 2012) e da localização de apreensão (em função das quatro macrorregiões do estado) usando a técnica de GC-MS aliada à análise multivariada (PCA), onde um total de 512 amostras foram investigadas. / Cocaine is a central nervous system (CNS) stimulant drug that causes psychological dependence. The duration of its effects depends on the form consumed (salt, e.g. cocaine hydrochloride, or base, e.g. crack) and on the mode of administration (snorting, smoking or injecting). Cocaine is defined as a tropanic alkaloid present in its structure by the tropane core. Despite its defined composition, aiming to increase the final amount of drug, illicit market applies a wide variety of diluent chemicals such as benzocaine, lidocaine, caffeine, procaine, among others. This project was divided into three chapters dedicated to: i) evaluating colorimetric, ie, the Scott test, using infrared spectroscopy with Fourier transform using Attenuated Total Reflection accessory (ATR-FTIR). Seventeen chemical additives were evaluated, which provided four false positives (promethazine, lidocaine, powdered milk and yeast). As the Scott test is performed and combined with spectroscopic techniques such as ATR-FTIR and chemometrics, conclusive results are obtained and can be used for routine forensic laboratories. ii) organic chemical profile of samples seized in the year 2012 in the months from January to July were analyzed using gas chromatography coupled to a quadrupole mass spectrometer (GC-MS) was studied. In this chapter, 101 samples were analyzed in full scan mode and 83 of these used to construct a model of principal component analysis (PCA). The main adulterants found were lidocaine, phenacetin and caffeine. Additionally, cocaine, lidocaine and caffeine were quantified from the selected ion monitoring (SIM), and their values of linearity, limits of detection and quantification determined. iii) samples of cocaine seized by the Civil Police were classified according to the time (2008, 2009, 2010, 2011 and 2012) and the location of apprehension (in relation to the four geographical regions of the state) using the technique of GC-MS associated with multivariate analysis (PCA), where a total of 512 samples were investigated.

Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-10Bitstream added on 2014-06-13T20:53:37Z : No. of bitstreams: 1 rocha_rsf_me_ilha.pdf: 3590200 bytes, checksum: f6889570ef205e6b46a549584c70a872 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As resinas compostas vêm sendo estudadas de longa data, sempre na procura de propiciar aos clínicos um melhor entendimento do seu processo de polimerização e a obtenção de melhores resultados nos procedimentos restauradores. A proposta deste trabalho foi determinar o grau de conversão, a microdureza e o coeficiente de expansão térmica das resinas restauradoras TPH Spectrum (Dentsply) e Filtek P60 (3M), em função da profundidade. Os materiais foram polimerizados por uma fonte de luz halógena durante 40 segundos em anéis de alumínio em diferentes espessuras (1, 2, 3 e 4 mm). O grau de conversão foi determinado através da espectroscopia no infravermelho próximo com transformada de Fourier, utilizando a razão entre bandas de absorção correspondentes às ligações duplas alifáticas e aromáticas. Para tanto, foram confeccionadas pastilhas contendo 20mg de resina e 150mg de KBr e os espectros foram obtidos em um espectrômetro Nexus 670 (Nicolet). As medidas de microdureza Vickers foram obtidas com um aparelho HMV 2000 (Shimadzu), utilizando uma amostra de cada espessura. A expansão térmica foi estudada através da técnica da extensometria. Os resultados mostraram que para as duas resinas ocorre uma diminuição no grau de conversão e na microdureza à medida que se aumenta a profundidade, como esperado. Para as medidas de expansão térmica, a resina Filtek P60 não apresentou diferenças significativas nas quatro profundidades, enquanto para a resina TPH Spectrum houve um aumento no coeficiente de expansão térmica com a profundidade. Não foi observada uma correlação entre o grau de conversão e a microdureza nas duas resinas estudadas. A determinação do grau de conversão através de espectros de absorção no infravermelho próximo mostrou-se mais preciso do que quando determinado a partir de espectros na região infravermelho médio. / The composite resins have been widely studied allowing a better understanding of the process of polymerization. As consequence, better results in the clinical procedures have been obtained. The purpose of this work was to study the degree of conversion, the hardness and the thermal expansion of the TPH Spectrum (Dentsply) and Filtek P60 (3M) resins in different depths. Samples were prepared for each resin using aluminum rings 10 mm in internal diameter and with different thickness (1, 2, 3, and 4 mm). Resin composites were cured with a halogen light curing unit for 40 s. The degree of conversion was determined from FTIR spectra by comparison of the aliphatic =CH2 bond at 4743 cm -1 with that of the aromatic component at 4623 cm -1 for the cured and uncured states. For that, pellets containing 20 mg of resin powder (cured or uncured) and 150 mg of KBr powder were made. The near infra-red spectra were obtained in a FT-IR spectrophotometer (model Nexus 670, Nicolet). The Vickers hardness was measured with a Micro Hardness Tester (model HMV 2000, Shimadzu). The thermal expansion was studied through the strain gauge technique. The results showed a decrease in the value of DC and hardness as increases the depth. For Filtek P60 resin, it was not observed significant difference in the coefficient of thermal expansion at different depths. On the other hand, an increase was observed in the coefficient as it increases the depth for the TPH Spectrum resin. There is not correlation between the conversion degree and the microhardness for the two studied resins. DC values more accurate were obtained from near infra-red spectra when compared with those obtained from medium infra-red spectra.

This thesis presents work based on the interactions of water soluble caboxylated zinc phthalocyanines (Pcs) and coreshell quantum dots (QDs). The Pcs are ZnPc(COOH)₈ and ZnPc(COOH)₄ and coreshell QDs are CdTe@ZnS-GSH. GSH = L-glutathione. Characterization and photophysical studies of conjugates were carried out. The approach of coordinating Pcs to QDs was achieved using an organic cross linker, N-N’-dicyclohexylcarbodiimide (DCC) at pH 10 at room temperature. Employing atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, infrared and X-ray photoelectron spectroscopies, the formation of the conjugates was confirmed. Upon conjugation with Pc derivatives, the fluorescence quantum yield of CdTe@ZnS-GSH decreased due to energy transfer from the QDs to the Pc. The average fluorescence lifetime of the CdTe@ZnS-GSH QD also decreased upon conjugation. The föster resonance energy transfer (FRET) behaviour of CdTe@ZnS-GSH-ZnPc(COOH)₄ conjugates was compared to that of CdTe@ZnS-GSH-ZnPc(COOH)₈. Higher FRET efficiencies were observed for CdTe@ZnS-GSH-ZnPc(COOH)₄-mixed or CdTe@ZnS-GSH-ZnPc(COOH)₄-linked compared to the corresponding CdTe@ZnS-GSH-ZnPc(COOH)₈-mixed or CdTe@ZnS-GSH-ZnPc(COOH)₈-linked. Triplet quantum yield (ΦT) and lifetime (ΤT) of ZnPc(COOH)₈ were found to increase in the presence of coreshell QDs. Though the singlet quantum yield (ΦΔ) value of ZnPc(COOH)8 was lower than ΦT , there was a slight upsurge in the ΦT in the presence of QDs. / Microsoft� Word 2010 / Adobe Acrobat 9.53 Paper Capture Plug-in

Avec l'objectif de réduire de la quantité de gaz à effets de serre dans l'atmosphère, les pouvoirs publics encouragent les pratiques ayant vocation à séquestrer du carbone dans les sols (reforestation, changement de pratiques agricoles). Pour en évaluer les réels bénéfices, des outils analytiques rapides, précis et peu coûteux sont nécessaires pour pouvoir comptabiliser précisément les stocks de carbone et leur évolution dans le temps. La Spectroscopie proche infrarouge (SPIR) est une technologie analytique adaptée à ce cahier des charges mais relève encore du domaine de la recherche en science du sol.Cette thèse s'est focalisée sur la première étape de cette méthode analytique: la formation du signal. Les sols étant des milieux très complexes, en termes de composition chimique et de structure physique, le signal spectroscopique est négativement impacté par les phénomènes de diffusion. Les conditions de la loi de Beer-Lambert n'étant plus remplies, les modèles chimiométriques pour prédire la teneur en carbone des sols sont moins précis et robustes. Nous proposons un système optique de mesure spectrale original et adapté aux milieux très diffusants, qui se base sur le principe de polarisation de la lumière. Il permet de sélectionner les photons ayant été moins impactés par le phénomène de diffusion. Ce signal est utilisé pour calculer un signal d'absorbance étant une bonne approximation de l'absorbance de Beer-Lambert.Ce dispositif, appelé PoLiS, a été validée expérimentalement sur des milieux modèles liquides et particulaires. Appliquée des sols pour prédire la teneur en carbone organique, les modèles de prédictions sont meilleurs avec l'absorbance calculée par PoLiS qu'avec l'absorbance calculée classiquement à partir de la mesure de réflectance. / With the goal of reducing the amount of greenhouse gases in the atmosphere, policy makers encourage practices intended to sequester carbon in soils (reforestation, changes in farming practices). New methods are required to rapidly and accurately measure soil C at field- and landscape-scales. Near infrared spectroscopy (NIRS) is an analytical technology adapted to these specifications but remains experimental research in soil science.This thesis has focused on the first step of this analytical method: signal formation. The soils are very complex materials, in terms of chemical composition and physical structure. Hence, the spectroscopic signal is negatively impacted by light scattering. Consequently, the conditions of the Beer-Lambert are no longer fulfilled, and the chemometric models to predict the carbon content of soils are less accurate and robust. We develop an original optical method based on light polarization spectroscopy to measure the absorbance of highly scattering materials. By selecting photons being less scattered, we compute a new absorbance signal which is a good approximation of the Beer-Lambert absorbance.This method, called Polis, was experimentally validated on model materials in liquid and powdered form. Applied on soils to predict Total Organic Content, the model built with the PoLiS absorbance outperform the models built with the classical absorbance computed from the diffuse reflectance signal.