Fourier self-deconvolution in coherent anti-Stokes Raman scattering spectrum analysis

Coherent anti-Stokes Raman scattering (CARS) microscopy is rapidly developing into a unique microscopic tool in biophysics, biology and the material sciences. The nonlinear nature of CARS spectroscopy complicates the analysis of the received spectra. There were developed mathematical methods for signal processing and for calculations spectra. Fourier self-deconvolution is a special high pass FFT filter which synthetically narrows the effective trace bandwidth features. As Fourier self-deconvolution can effectively reduce the noise, which may be at a higher spatial frequency than the peaks, without losing peak resolution. The idea of the work is to experiment the possibility of using wavelet decomposition in spectroscopic for background and noise removal, and Fourier transformation for linenarrowing.

Fourier-based registration for robust forward-looking sonar mosaicing in low-visibility underwater environments

Vehicle operations in underwater environments are often compromised by poor visibility conditions. For instance, the perception range of optical devices is heavily constrained in turbid waters, thus complicating navigation and mapping tasks in environments such as harbors, bays, or rivers. A new generation of high-definition forward-looking sonars providing acoustic imagery at high frame rates has recently emerged as a promising alternative for working under these challenging conditions. However, the characteristics of the sonar data introduce difficulties in image registration, a key step in mosaicing and motion estimation applications. In this work, we propose the use of a Fourier-based registration technique capable of handling the low resolution, noise, and artifacts associated with sonar image formation. When compared to a state-of-the art region-based technique, our approach shows superior performance in the alignment of both consecutive and nonconsecutive views as well as higher robustness in featureless environments. The method is used to compute pose constraints between sonar frames that, integrated inside a global alignment framework, enable the rendering of consistent acoustic mosaics with high detail and increased resolution. An extensive experimental section is reported showing results in relevant field applications, such as ship hull inspection and harbor mapping

Filtros digitais por transformadas de Fourier aplicados em eletroquímica

The electrochemical properties of micro and nano-electrodes are widely investigated due to their low faradaic and capacitive currents, leading to a new generation of smart and implantable devices. However, the current signals obtained in low-dimensional devices are strongly influenced by noise sources. In this paper, we show the evaluation of filters based on Fast Fourier Transform (FFT) and their implementation in a graphical user interface (GUI) in MATLAB®. As a case study, we evaluated an electrochemical reaction process of charge transfer via outer-sphere. Results showed successful removal of most of the noise in signals, thus proving a promising tool for low-scale measurement.

Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and chemometric techniques for the determination of adulteration in petrodiesel/biodiesel blends

We propose an analytical method based on fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy to detect the adulteration of petrodiesel and petrodiesel/palm biodiesel blends with African crude palm oil. The infrared spectral fingerprints from the sample analysis were used to perform principal components analysis (PCA) and to construct a prediction model using partial least squares (PLS) regression. The PCA results separated the samples into three groups, allowing identification of those subjected to adulteration with palm oil. The obtained model shows a good predictive capacity for determining the concentration of palm oil in petrodiesel/biodiesel blends. Advantages of the proposed method include cost-effectiveness and speed; it is also environmentally friendly.

Análise exploratória aplicada a espectros de reflexão total atenuada no infravermelho com transformada de Fourier (ATR-FTIR) de blendas de biodiesel/diesel

In this study, hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used to classify blends produced from diesel S500 and different kinds of biodiesel produced by the TDSP methodology. The different kinds of biodiesel studied in this work were produced from three raw materials: soybean oil, waste cooking oil and hydrogenated vegetable oil. Methylic and ethylic routes were employed for the production of biodiesel. HCA and PCA were performed on the data from attenuated total reflectance Fourier transform infrared spectroscopy, showing the separation of the blends into groups according to biodiesel content present in the blends and to the kind of biodiesel used to form the mixtures.

Application of fourier transform infrared spectroscopy, chemical and chemometrics analyses to the characterization of agro-industrial waste

Agroindustrial waste in general presents significant levels of nutrients and organic matter and has therefore been frequently put to agricultural use. In this context, the objective of this study was to determine the chemical composition, nitrogen, phosphorus, potassium, calcium, magnesium and carbon content, as well as the qualitative characteristics through Fourier transform infrared spectroscopy of four samples of poultry litter and one sample of cattle manure, from the southwestern region of Paraná, Brazil. Results revealed that, in general, the poultry litter presented higher amount of nutrients and carbon than the cattle manure. The infrared spectra allowed identification of the functional groups present and the differences in degree of sample humification. The statistical treatment confirmed the quantitative and qualitative differences revealed.

Influence of the Al content on the phase transformations in Cu-Al-Ag alloys

The influence of the Al content on the phase transformations in Cu-Al-Ag alloys was studied by classical differential thermal analysis (DTA), optical microscopy (OM) and X-ray diffractometry (XRD). The results indicated that the increase in the Al content and the presence of Ag decrease the rate of the b1 phase decomposition reaction and contribute for the raise of this transition temperature, thus decreasing the stability range of the perlitic phase resulted from the b1 decomposition reaction.

Catalytic transformations of fatty acid derivatives for food, oleochemicals and fuels over carbon supported platinum group metals

Växtoljor som utgör en förnybar naturresurs används som sådana eller i modifierade former i många industriella processer, som är av stor betydelse för vårt vardagliga liv. Växtoljor används i livsmedel, i kemiska och farmaceutiska produkter, i textilindustrin, för framställning av färgämnen och beläggningsmaterial samt som miljövänliga bränslekomponenter. Fetter och oljor hör till de äldsta kemiska komponenterna som utnyttjas av människan. De består huvudsakligen av glycerolestrar och fettsyror. Fetter och oljor har typiskt en kolkedja med kol-koldubbelbindningar samt karboxyl- och estergrupper, som kan genom hydrering eller dekarboxylering konverteras till nyttiga och miljövänliga produkter med hjälp av ädelmetallkatalysatorer. Aktivt kol (C) används som bärare på katalysatorerna. Väteaddition, d.v.s. hydrering av växtoljor har varit föremål för omfattande forskning i över hundra års tid. Hydreringen är en viktig process, för den tillämpas på produktion av fetter och margarin. Omättade fettsyror hydreras traditionellt på nickelbaserade heterogena katalysatorer. Samtidigt med en partiell hydrering av fettsyrorna och fettsyraestrarna som har två dubbelbindningar pågår också isomeringsreaktioner, vilka ger cis- och transisomerer av reaktantmolekylerna. Den största nackdelen med nickelkatalysatorerna är deras giftighet samt bildning av ohälsosamma transisomerer i reaktionsprodukterna. Dessutom deaktiveras nickelkatalysatorn snabbt p.g.a. att nickeltvålar bildas i reaktionsblandningen. Platinabaserade katalysatorer lider däremot inte av dessa begränsningar. Metaller i platinagruppen i det periodiska systemet studerades i detalj för att avslöja kinetiska effekter i hydreringen av cis-metyloleat. Palladium, rutenium, rhodium, platina och iridium användes som katalytiska metaller. Metallhalten på aktivkolbärare var 1 vikt-%. De olika platinametallerna undersöktes för att kartlägga konkurrerande hydrerings- och isomeringsrutter på metallerna. Det visade sig att metallerna i andra raden av det periodiska systemet (Ru, Rh, Pd) är aktivare i isomeringsprocesserna, medan metallerna i tredje raden (Ir, Pt) har en lägre aktivitet. Pd/C valdes bland platinametallerna, för att den är attraktiv ur ekonomisk synvinkel och den är mycket aktiv och selektiv, speciellt jämfört med nickel. Tyngdpunkten i arbetet var utvecklingen av en alternativ, palladiumbaserad hydreringsteknologi som skulle ersätta den traditionella teknologin som är baserad på användningen av nickelkatalysatorer. Palladiumbaserade katalysatorer kan återcirkuleras, de är aktivare och mera resistenta mot syror och de bildar mindre mängder av skadliga transisomerer. För att denna teknologi skall bli ekonomiskt hållbar och konkurrenskraftig, måste den basera sig på de bästa möjliga katalysatorerna, vilket innebär att en optimal kombination av hög aktivitet och selektivitet samt en lång livstid för katalysatorn krävs. Därför inkluderades teknologiska aspekter kraftigt i forskningen. Mycket arbete satsades på design av palladium på en mesoporös kolbärare och undersökning av korrelationerna mellan katalysatorns egenskaper och dess aktivitet i isomeriseringsreaktionerna och i hydreringen av kol-koldubbelbindningarna i reaktantmolekylen. Katalysatorerna karakteriserades med många fysikaliska och kemiska metoder (transmissionselektronmikroskopi (TEM), röntgendiffraktion (XRD), röntgenfotoelektronspektroskopi (XPS), temperaturprogrammerad reduktion (TPR), temperaturprogrammerad desorption (TPD) av kolmonoxid, kemisorption av kolmonoxid, fysisorption av kväve). Temperaturens, vätetryckets och katalysatorkoncentrationens inverkan på fettsyra- och isomersammansättningen hos de hydrerade oljorna bestämdes under kinetiska betingelser, i frånvaro av massöverföringseffekter. Syreavspjälkning genom fullständig dekarboxylering av karboxylgruppen i fettsyramolekylen är det hittills bästa sättet att framställa miljövänlig dieselolja, eftersom linjära paraffiner fås som reaktionsprodukter och en tillsats av dyr vätgas undviks. Deoxygeneringen undersöktes systematiskt på en Pd/C-katalysator (Sibunit) genom att använda mättade fettsyror C16-C20 och C22 som råvara. Produktmolekylen blev en dieselliknande kolvätemolekyl, med en kolatom färre än i utgångsmolekylen. Lika stora dekarboxyleringshastigheter observerades för rena, mättade fettsyror. En jämförelse av deoxygenereringshastigheterna för stearin-, olein- och linolsyra som råvara vid 300oC i närvaro av 1-volymprocent väte på mesoporös Pd/C (Sibunit) avslöjade att katalysatorns aktivitet och selektivitet ökade med en ökande mättningsgrad av reaktantmolekylen. Då stearinsyra användes som utgångsmolekyl, bestod huvudprodukterna av önskade C17-kolväten, medan mängden av aromatiska C17-komponenter ökade, då olein- och linolsyra användes som utgångsmolekyler. Katalysatordeaktiveringen var relativt påfallande vid deoxygeneringen av linolsyra så att endast 3% av fettsyrorna omsattes till produkter i 330 min. Deaktiveringen orsakades av aromatiska C17-komponenter samt av fettsyradimerer, som bildades via en Diels-Alderreaktion. Hydreringen av omättade fettsyror kan därför rekommenderas som ett primärt kemiskt steg i framställningen av miljövänliga dieselprodukter. Målet var också att öka förståelsen av palladiummetallernas roll i nanoskala, speciellt effekten av metallpartiklarna i katalytisk hydrering och deoxygenering. Pd/C-katalysatorer med lika stora halter av Pd syntetiserades och metallens dispersion på bärarmaterialet varierades systematiskt genom en kontrollerad uppväxt av palladiumnanopartiklar på aktiv kolbärare. Metalldispersionens effekt på hydrerings-hastigheten och cis-transförhållandet undersöktes i detalj. En optimal metalldispersion som gav den högsta dekarboxyleringshastigheten hittades. Massöverföringens inverkan på reaktionens hastighet studerades experimentellt och temperaturprogrammerad desorption av kolmonoxid från katalysatorytan undersöktes ingående. Hydrering av växtoljor genomfördes under satsvisa och kontinuerliga betingelser. Både finfördelat Pd/C och katalysatorgranulat användes i experimenten. Ett av målen med arbetet var uppskalningen av hydreringsprocesserna. Med tanke på stora produktionsvolymer var det logiskt att undersöka kontinuerliga hydrerings- och dekarboxyleringsteknologier. En kontinuerlig packad bäddreaktor studerades i laboratorieskala, vilket gav viktig information om katalysatorns långtidsstabilitet och deaktivering. Effekten av rena fettsyror och triglycerider som råvara samt metallpartikelstorleken och palladiumhalten studerades med hjälp av den kontinuerliga reaktorn. Produktionskapaciteten som erhölls med satsvis och kontinuerlig drift jämfördes. Dekarboxyleringen av stearinsyra undersöktes också i en kontinuerlig packad bädd. Omsättningsgraden blev 15% för en stabil katalysator.

Aplicação da análise harmônica por séries de Fourier para a previsão de produtividade da cultura do café no Estado de Minas Gerais

O objetivo deste trabalho foi obter um modelo de previsão de produtividade para a cultura do café, em sete municípios do Estado de Minas Gerais. Submeteram-se à análise harmônica por séries de Fourier, séries de produtividades representativas de cada município, das quais se extraíram os coeficientes até o sétimo harmônico, submetendo-os à regressão linear múltipla nos três primeiros componentes principais de um conjunto de 33 variáveis inerentes à produção cafeeira. Essas variáveis foram médias de 15 anos correspondentes aos mesmos anos das produtividades e subdivididos em quatro períodos trimestrais, ao longo do ciclo produtivo da cultura (julho a junho). O modelo mostrou-se inconsistente, apresentando erros das estimativas bastante discrepantes, evidenciando a complexidade de modelagem de previsão de safras para a cultura do café.

Catalysis by gold for biomass transformations

The development of new technologies to supplement fossil resources has led to a growing interest in the utilization of alternative routes. Biomass is a rich renewable feedstock for producing fine chemicals, polymers, and a variety of commodities replacing petroleumderived chemicals. Transformation of biomass into diverse valuable chemicals is the key concept of a biorefinery. Catalytic conversion of biomass, which reduces the use of toxic chemicals is one of the important approaches to improve the profitability of biorefineries. Utilization of gold catalysts allows conducting reactions under environmentally-friendly conditions, with a high catalytic activity and selectivity. Gold-catalyzed valorization of several biomass-derived compounds as an alternative approach to the existing technologies was studied in this work. Isomerization of linoleic acid via double bond migration towards biologically active conjugated linoleic acid isomers (CLA) was investigated. The activity and selectivity of various gold catalysts towards cis-9,trans-11-CLA and trans-10,cis-12-CLA were investigated in a semi-batch reactor, showing that the yield of the desired products varied, depending on the catalyst support. The structure sensitivity in the selective oxidation of arabinose was demonstrated using a series of gold catalysts with different Au cluster sizes in a shaker reactor operating in a semibatch mode. The gas-phase selective oxidation of ethanol was studied and the influence of the catalyst support on the catalytic performance was investigated. The selective oxidation of the lignan hydroxymatairesinol (HMR), extracted from the Norway spruce (Picea abies) knots, to the lignan oxomatairesinol (oxoMAT) was extensively investigated. The influence of the reaction conditions and catalyst properties on the yield of oxoMAT was evaluated. In particular, the structure sensitivity of the reaction was demonstrated. The catalyst deactivation and regeneration procedures were studied. The reaction kinetics and mechanism were advanced.

Character transformations and their functional significance as a key to the evolution of hystricognath Rodentia

Hystricognathi represent a monophyletic taxon within Rodentia. Since phylogenetically analyzed morphological systems are essential for revealing evolutionary processes, this study identifies evolutionary character transformations on the stem lineage of Hystricognathi as derived from the author's own work and the literature. Data so far indicate that evolutionary transformations in the rostral head region, the loss of tactile ability in the outer nasal skin and the mobile arrangement of the associated cartilage, were allied with a switch from omnivorous to herbivorous and fiber-rich nutrition. Additional character transformations in the skull assist in digesting such food. Structures associated with reproduction and placentation show a remarkable pro portion of derived character conditions: the chorioallantoic placenta has a ring-shaped organization and growth structure which optimizes the capacity for passive diffusion, a subplacenta occurred as a specialized region responsible for placental invasion and the inverted yolk sac facilitates substance exchange with the main placenta. Finally, precocial newborns evolved as a derived condition within Rodentia. All things considered, a mode of reproduction is indicated, which does not demand excessive additional energy intake by the mother and is in accordance with her low energetic diet. Hystricognathi possess major character transformations that represent prerequisites for their successful radiation at the time when more open ecosystems and grasslands evolved during Earth history. The analysis resulted in the reconstruction of a life-near picture of the hystricognath stem species pattern with high explanatory power in terms of changes in space and time and their interdependence with biodiversity.

Terpenoid transformations over gold catalysts

Nowadays biomass transformation has a great potential for the synthesis of value-added compounds with a wide range of applications. Terpenoids, extracted from biomass, are inexpensive and renewable raw materials which often have a biological activity and are widely used as important organic platform molecules in the development of new medicines as well as in the synthesis of fine chemicals and intermediates. At the same time, special attention is devoted to the application of gold catalysts to fine chemical synthesis due to their outstanding activity and/or selectivity for transformations of complex organic compounds. Conversion of renewable terpenoids in the presence of gold nanoparticles is one of the new and promising directions in the transformation of biomass to valuable chemicals. In the doctoral thesis, different kinds of natural terpenoids, such as α-pinene, myrtenol and carvone were selected as starting materials. Gold catalysts were utilized for the promising routes of these compounds transformation. Investigation of selective α-pinene isomerization to camphene, which is an important step in an industrial process towards the synthesis of camphor as well as other valuable substrates for the pharmaceutical industry, was performed. A high activity of heterogeneous gold catalysts in the Wagner-Meerwein rearrangement was demonstrated for the first time. Gold on alumina carrier was found to reach the α-pinene isomerization conversion up to 99.9% and the selectivity of 60-80%, thus making this catalyst very promising from an industrial viewpoint. A detailed investigation of kinetic regularities including catalyst deactivation during the reaction was performed. The one-pot terpene alcohol amination, which is a promising approach to the synthesis of valuable complex amines having specific physiological properties, was investigated. The general regularities of the one-pot natural myrtenol amination in the presence of gold catalysts as well as a correlation between catalytic activity, catalyst redox treatment and the support nature were obtained. Catalytic activity and product distribution were shown to be strongly dependent on the support properties, namely acidity and basicity. The gold-zirconia (Au/ZrO2) catalyst pretreated under oxidizing atmosphere was observed to be rather active, resulting in the total conversion of myrtenol and the selectivity to the corresponding amine of about 53%. The reaction kinetics was modelled based on the mechanistic considerations with the catalyst deactivation step incorporated in the mechanism. Carvone hydrogenation over a gold catalyst was studied with the general idea of investigating both the activity of gold catalysts in competitive hydrogenation of different functional groups and developing an approach to the synthesis of valuable carvone derivatives. Gold was found to promote stereo- and chemoselective carvone hydrogenation to dihydrocarvone with a predominant formation of the trans-isomer, which generally is a novel synthetic method for an industrially valuable dihydrocarvone. The solvent effect on the catalytic activity as well as on the ratio between trans- and cis-dihydrocarvone was evaluated.

Critical analysis of autoregressive and fast Fourier transform markers of cardiovascular variability in rats and humans

The autonomic nervous system plays an important role in physiological and pathological conditions, and has been extensively evaluated by parametric and non-parametric spectral analysis. To compare the results obtained with fast Fourier transform (FFT) and the autoregressive (AR) method, we performed a comprehensive comparative study using data from humans and rats during pharmacological blockade (in rats), a postural test (in humans), and in the hypertensive state (in both humans and rats). Although postural hypotension in humans induced an increase in normalized low-frequency (LFnu) of systolic blood pressure, the increase in the ratio was detected only by AR. In rats, AR and FFT analysis did not agree for LFnu and high frequency (HFnu) under basal conditions and after vagal blockade. The increase in the LF/HF ratio of the pulse interval, induced by methylatropine, was detected only by FFT. In hypertensive patients, changes in LF and HF for systolic blood pressure were observed only by AR; FFT was able to detect the reduction in both blood pressure variance and total power. In hypertensive rats, AR presented different values of variance and total power for systolic blood pressure. Moreover, AR and FFT presented discordant results for LF, LFnu, HF, LF/HF ratio, and total power for pulse interval. We provide evidence for disagreement in 23% of the indices of blood pressure and heart rate variability in humans and 67% discordance in rats when these variables are evaluated by AR and FFT under physiological and pathological conditions. The overall disagreement between AR and FFT in this study was 43%.