This diploma thesis is about forensic multivariate soil analysis in the localities Ostrava and Tinec. A total of 52 samples were taken in the areas near metallurgical companies. These samples were measured for concentrations of chromium, manganese, copper, nickel, lead, mercury and zinc. Mercury concentration was analysed using AMA 254 device. The remaining metals were determined by flame atomic absorption spectrometry (FâAAS). Additionally, IR spectra were acquired by Fourier transform infrared spectroscopy (FTIR) using diffusion reflectance technique (DRIFT). In the end the results were used to create correlation models and statistical models of PCA (principal component analysis) methods with CA (correlation analysis).

Enzyme design is a steadily growing field of computational chemistry, but its successes are limited by the current available knowledge and application of enzyme conformational dynamics. In this work a series of FTIR and 2D IR spectroscopic methods, for observing the conformational dynamics of an enzymatic active site and its surrounding residues, are characterized. The enzyme model system for these studies is the promiscuous ene-reductase from Pyrococcus horikoshii (PhENR) which is capable of binding substrates in multiple orientations. In one method, the spectral lineshape of an aryl-nitrile substrate-analog vibrational label is analyzed using a frequency fluctuation correlation function (FFCF) and compared to the lineshape of a corresponding aryl-azide label. This analysis revealed dynamic and electrostatic active site anisotropy which may influence substrate catalysis. The second method utilizes the intramolecular vibrations of the enzymatic cofactor, flavin mononucleotide (FMN), which is shown to be sensitive to electric field changes associated with substrate binding. The final method places a site-specific nonnatural amino acid containing an azide probe within the enzyme’s hydrophobic core. Additionally, a double-mutant cycle was identified via a common design program, the Rosetta Modeling Suite, and used to analyze the effects of mutation on enzyme dynamics. Altogether, these methods demonstrate the ability of 2D IR spectroscopy to observe enzyme conformational dynamics. Application of these methods to various other enzyme model systems should provide valuable insight for the improvement of future dynamic enzyme design protocols.

Dans la technologie à l'hydrogène, l'oxydation préférentielle du CO en excès d'hydrogène (réaction PrOx) est un processus important pour l'obtention d'hydrogène sans CO pour les piles à combustible à membrane échangeuse de protons (PEMFC). Les catalyseurs à base de PtCu sont l’un des systèmes les plus étudiés pour les dispositifs mobiles en raison de leur bilan d’activité / sélectivité élevé et de leurs propriétés chimiques et mécaniques appropriées pour les procédures de démarrage / arrêt dans les conditions de fonctionnement des processeurs de combustible.Récemment, l'utilisation de catalyseurs bimétalliques Pt-Cu avec une activité et une sélectivité excellentes vis-à-vis de l'oxydation du CO a été rapportée pour la réaction PrOx. Cependant, la nature des phases actives et le rôle des deux métaux au cours de la réaction ne sont pas clairement démontrés.Pour comprendre ce système, il est nécessaire de créer un catalyseur modèle qui facilite l’étude. Ainsi, des nanoparticules d'alliage bimétallique Pt-Cu bien définies ont été synthétisées et étudiées par des techniques d'Operando permettant de comprendre les modifications électroniques de surface de l'interface solide-gaz du catalyseur modèle mentionné ci-dessus dans des conditions de réaction PrOx.Dans ce travail, la composition et la nature des espèces présentes à la surface du catalyseur dans des conditions de réaction bien contrôlées ont été étudiées, en particulier du point de vue de la dynamique de surface, des transitions structurelles et des effets possibles de l’atmosphère de réaction et des couches superposées adsorbées sur la surface. composition superficielle et structure de l'alliage. / In the Hydrogen technology, the preferential oxidation of CO in excess of hydrogen (PrOx reaction) is an important process for obtaining CO-free hydrogen for proton exchange membrane fuel cells (PEMFCs). PtCu based catalysts are one of the most studied systems for mobile devices because of their high activity/selectivity balance and their appropriate chemical and mechanical properties for the start-up/shut-down procedures during fuel processors operation conditions.Recently, the use of Pt-Cu bimetallic catalysts with excellent activity and selectivity towards CO oxidation was reported for PrOx reaction. However, there are not clear evidences off the nature of the active phases and the role of both metals during the reaction.To understand this system it is necessary to create a model catalyst which facilitates the study. Thus, well-defined Pt-Cu bimetallic alloy nanoparticles were synthetized and studied by Operando techniques allowing the comprehension of the surface electronic modifications in the solid-gas interface of the above mentioned model catalyst under PrOx reaction conditions.In this work, the composition and nature of the species present on the catalyst surface upon well-controlled reaction conditions were studied, in particular from the point of view of surface dynamics, structural transitions and the possible effects of reaction atmosphere and adsorbed overlayers on the surface composition and structure of the alloy.

Wetting of a substance has been widely investigated since it has many applications to many different fields. Wetting principles can be applied to better select cleans for front end of line (FEOL) and back end of line (BEOL) cleaning processes. These principles can also be used to help determine processes that best repel water from a semiconductor device. It is known that the value of the dielectric constant in an insulator increases when water is absorbed. These contact angle experiments will determine which processes can eliminate water absorption. Wetting is measured by the contact angle between a solid and a liquid. It is known that roughness plays a crucial role on the wetting of a substance. Different surface groups also affect the wetting of a surface. In this work, it was investigated how wetting was affected by different solid surfaces with different chemistries and different roughness. Four different materials were used: silicon; thermally grown silicon dioxide on silicon; chemically vapor deposited (CVD) silicon dioxide on silicon made from tetraethyl orthosilicate (TEOS); and organosilicate glass (OSG) on silicon. The contact angle of each of the samples was measured using a goniometer. The roughness of the samples was measured by atomic force microscopy (AFM). The chemistry of each of the samples were characterized by using X-ray photoelectron spectroscopy (XPS) and grazing angle total attenuated total reflection Fourier transform infrared spectroscopy (FTIR/GATR). Also, the contact angle was measured at the micro scale by using an environmental scanning electron microscope (ESEM).

Light absorption in metal catalyst nanoparticles can excite charge carriers to generate hot electron (and complimentary hot holes) with energy higher than the Fermi level. When hot electrons possess energy high enough, they exhibit a high tendency to inject into antibonding orbitals of adsorbates on the photoexcited metal nanoparticles, weakening the corresponding chemical bonds to promote chemical reactions with accelerated reaction kinetics and improved selectivity. Such hot-carrier chemistry has been reported on plasmonic metal nanoparticles, such as silver and gold, which exhibit strong surface plasmon resonances (SPRs) and strong light absorption. However, these metal nanoparticles are not suitable catalysts because their affinity toward interesting molecules is limited. In contrast, most transition metals, such as platinum-group metals and early transition metals, are industrially essential catalysts, but light absorption power in metal nanoparticles is low due to the absence of SPRs in the visible spectral range. Therefore, it is intriguing to explore the potential of hot-carrier catalytic chemistry on photoexcited non-plasmonic metal nanoparticles. Upon the absorption of the same optical power, metal nanoparticles with a small size usually exhibit a high probability of hot electron production and high efficiency of injecting hot electrons into adsorbates. It is challenging to have strong light absorption power and operation stability of the catalyst metal nanoparticles with small sizes. In this thesis, dielectric light antenna, i.e., spherical silica nanoparticles with strong surface scattering resonances near their surfaces, is introduced to support the metal catalyst nanoparticles, enabling improved light absorption power in the metal nanoparticles and operation stability. This thesis focuses on ultrafine rhodium (Rh) nanoparticles (with sizes ranging from 1.7 nm to 4.2 nm) that are widely used as thermal catalysts in many important industry reactions, especially for oxygen-containing species conversion, an oxyphilic feature of Rh nanoparticles. Firstly, this dissertation conducted a comparative study to investigate the influence of silica geometry, nanospheres, and rodlike nanoparticles on the light absorption of Rh nanoparticles. Both silica substrates enhanced the light absorption of loaded Rh nanoparticles due to elongated light scattering paths (random scattering) and enhanced electromagnetic field intensity (resonant scattering). However, silica nanospheres support both resonant scattering and random light scattering modes, exhibiting a higher Rh absorption than the usage of rodlike silica nanoparticles. The light resonant scattering modes on highly symmetrical silica nanospheres enable producing "hot spots" with a much higher electromagnetic field intensity than incident light intensity. This study then investigated the effect of silica geometries on photocatalytic performance. The CO2 hydrogenation was studied as a model reaction. The Rh/silica nanosphere system exhibited a faster photocatalytic kinetic than the case of rodlike silica nanoparticles. It is possibly due to the enhanced light power density around the silica nanospheres. The results give a promise of expanding Rh nanoparticles from thermo-catalysis to photocatalysis. Secondly, this dissertation moves onto accelerating aerobic oxidation of primary alcohols to aldehydes, which was benefited from activated oxygen molecules by hot electron injection. This study found that photoexcited Rh nanoparticles enabled accelerating the alcohol oxidation kinetics by four times at a light power intensity of 0.4 W cm-2, accompanied by a reduced activation energy of 21 kJ mol-1. The derived Langmuir-Hinshelwood rate equation was used to fit the oxygen partial pressure results. Photo-illumination promotes the cleavage of associatively adsorbed oxygen molecules into adsorbed oxygen atoms, reducing the energy barrier. Besides, the silica-supported Rh nanoparticles exhibited a higher photocatalytic performance because of the good colloidal stability and enhanced light absorption of small-sized Rh particles. This part of the dissertation shows the possibility of hot-electron mediated reaction pathways towards a desirable kinetic of alcohol oxidation. Thirdly, it will be meaningful to use the abstracted protons from cheap alcohol sources to reduce other organic molecules rather than dangerous hydrogen gas. This dissertation then investigated the possibility of using an isopropanol solvent as a hydrogen source to reduce nitrobenzene and the feasibility of enhancing the selectivity of the reaction with the light illumination. The results showed that the isopropanol was spontaneously oxidized, producing acetone. Light illumination onto Rh particles selectively enhanced the coupling of reduced nitrobenzene intermediates to produce azoxybenzene. The selectivity of nitrobenzene and production rates gradually increased with a higher number of light photons. Photo-illumination promotes both aniline and azoxybenzene production rates. Hot electrons on Rh particles possibly enabled activating nitrobenzene molecules and increasing concentrations of reduced nitrobenzene intermediates. It resulted in a higher possibility of condensation product and azoxybenzene selectivity, which could not be obtained by elevating temperature without light illumination. This part of the work demonstrated the feasibility of hot electrons from Rh nanoparticles to tune the reaction selectivity in a liquid phase. Lastly, it is challenging to modulate the selectivity of CH4 from CO2 hydrogenation because of the competitive CO production. This dissertation moves towards enhancing both kinetic rates and selectivity of CH4 for gaseous CO2 hydrogenation by photoexcited Rh nanoparticles. Light illumination onto Rh/silica nanosphere particles resulted in the selectivity of CH4 over 99% in contrast to ~70% under dark conditions at 330 oC and with an absorbed light power intensity of 1.5 W cm-2. The activation energy of CH4 production and CO2 consumption gradually decreased with higher light power intensity because of the transient injection of hot electrons into adsorbates to activate intermediates. Increasing operating temperature and light power intensity synergistically enhanced the reaction kinetics. Besides, a middle-sized Rh nanoparticle showed a better photocatalytic performance than that of the largest-sized Rh nanoparticles because of the balance in hot-electron production efficiency and intrinsic catalytic performance. Partial pressure dependence and in situ infrared characterizations showed that the critical stable intermediates for CH4 production should be hydrogenated CO2 species (HCOO* COOH*) and hydrogenated CO* species (carbonyl hydride or HxCO*). The light illumination exclusively enhanced the dissociation of CO2 and CO* without apparent influence on CO* desorption. Under high reaction temperature, light illumination preferred a faster CO* conversion than CO2 dissociation, leading to high CH4 selectivity. This result was also supported by higher methanation rates of CO gas under light illumination. The infrared result showed a reduced stretching frequency of CO*, which supported the possibility of the electron from Rh back-donating into antibonding orbitals of strongly adsorbed CO* species. However, hot electrons from silver nanoparticles with a weak COOH* or CO* adsorption could not efficiently activate carbon-species and could not promote CO2 hydrogenation kinetics. This dissertation offers an avenue of enhancing light absorption of small-sized Rh nanoparticles and expanding its usage from thermal catalysis to photocatalysis for driving oxidation and reduction reactions. The reactants share a common feature containing oxygen elements, a strong affinity with rhodium metal for efficient hot electron injection. We studied the light power intensity and temperature-dependence, showing the accelerated reaction kinetics by hot electron-driven pathways. Photo-excited rhodium nanoparticles were believed to promote the cleavage of chemical bonds O-O, N-O, and C-O to drive chemical transformations. The findings offer insights into developing the scope of non-plasmonic metal nanoparticles in photocatalytic reactions for industrial applications. / Chemistry

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Currently there is no known method for accurately measuring the temperature of the gas phase of combustion products within a solid fuel flame. The industry standard is a suction pyrometer and thermocouple which is intrusive, both spatially and temporally averaging, and difficult to use. In this work a new method utilizing the spectral emission from water vapor is investigated through modeling and experimental measurements. This method was demonstrated along a 0.75m line of sight, averaged over 1 minute in the products of a natural gas flame but has the potential to produce a spatial resolution on the order of 5 cm and a temporal resolution of less than 1 millisecond. The method employs the collection of infrared emission from water vapor over discrete wavelength bands and then uses the ratio of those emissions to infer temperature. A 12.5 mm lens has been positioned within a water cooled probe to focus flame product gas emission into an optical fiber where the light is transmitted to a Fourier Transform Infrared Spectrometer (FTIR). The same optical setup was also used to collect light from a black body cavity at a known temperature in order to calibrate the spectral sensitivity of the optical system and FTIR detector. Experiments were conducted in the product gas of a 150 kWth methane flame comparing the optical emission results to a suction pyrometer with type K thermocouple. The optical measurement produced gas temperatures approximately 1 - 4% higher than the suction pyrometer. Broadband background emission was also seen by the optical measurement and was removed assuming grey body radiation. This background emission can be used to determine particle emission temperature and intensity. Additional work will be needed to demonstrate the method under conditions with significant particle emission. Additional work is also needed to demonstrate the work over a smaller path length and shorter time scale.

Yes / Poloxamers or Pluronics®-based nanogels are one of the most used matrices for developing delivery systems. Due to their thermoresponsive and flexible mechanical properties, they allowed the incorporation of several molecules including drugs, biomacromolecules, lipid-derivatives, polymers, and metallic, polymeric, or lipid nanocarriers. The thermogelling mechanism is driven by micelles formation and their self-assembly as phase organizations (lamellar, hexagonal, cubic) in response to microenvironmental conditions such as temperature, osmolarity, and additives incorporated. Then, different biophysical techniques have been used for investigating those structural transitions from the mechanisms to the preferential component’s orientation and organization. Since the design of PL-based pharmaceutical formulations is driven by the choice of the polymer type, considering its physico-chemical properties, it is also relevant to highlight that factors inherent to the polymeric matrix can be strongly influenced by the presence of additives and how they are able to determine the nanogels biopharmaceuticals properties such as bioadhesion, drug loading, surface interaction behavior, dissolution, and release rate control. In this review, we discuss the general applicability of three of the main biophysical techniques used to characterize those systems, scattering techniques (small-angle X-ray and neutron scattering), rheology and Fourier transform infrared absorption spectroscopy (FTIR), connecting their supramolecular structure and insights for formulating effective therapeutic delivery systems. / The Sao Paulo Research Foundation - FAPESP (Grant 2019/20303-4; 2019/14773-8), National Council for Scientifc and Technological Development - CNPq (308819/2022-0), ERASMUS Program Fellowship, and The Coordination for the Improvement of Higher Education Personnel - Brazil (CAPES) - Finance Code 001. / The full-text of this article will be released for public view at the end of the publisher embargo on 29th July 2024.

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