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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Aproveitamento analítico da extratibilidade de sais de fosfônio na separação e determinação de irídio, ródio e ósmio / Analytical use of the extractibility of phosphonium salts in the separation and determination of iridium, rhodium and osmium

Jaim Lichtig 31 December 1971 (has links)
A extratibilidade de sais de fosfônio foi aproveitada para elaborar método de separação Ir-Rh, mediante a extração do sal de trifenil n-propil fosfônio do cloro-complexo de Ir(IV,) em clorofórmio. O coeficiente de extração de 99,2%, permite retirar o irídio do meio aquoso com grande eficiência. O irídio assim separado é determinado diretamente, por via espectrofotométrica, em 494 mµ, em faixa de concentração de 5,0 a 50,0 µg/ml. Pd(II), Pt(IV) e Os(IV) interferem e são eliminados previamente, assim como Au(III). Os ânions interferentes, I-, Br- e SCN- são também eliminados previamente. Muitos íons podem estar presentes, tais como Co(II),Cu(II), Mn(II), Fe(III), Ni(II), As(V), Sb(V), NO3-, ClO4- e SO4--. Após a separação do Ir (IV), o Rh(III) que permanece, na solução é complexado com íons azoteto e extraído em clorofórmio depois de precipitado com íons trifenil n-propil fosfônio, sendo o coeficiente de extração de 98,3%. A determinação ê também feita no próprio solvente, mediante medida espectrofotométrica em 404-408 mµ, para um intervalo de concentração de . 10,0 a 70,0 µg/ml. Uma separação envolvendo Os(IV), Pd(II)e Pt(IV) foi elaborada, eliminando-se Pd(II) e Pt(IV) por extração de ambos em metil n-butil cetona a partir de uma solução contendo SCN-. O Os(IV) é determinado na solução aquosa na forma de OsC16-- por medida espectrofotométrica em 370 mµ, válida para a faixa de concentração de 2,0 a 20,0 µg/m1. / Abstract not available.
232

Filmes sensíveis a pressão pela técnica de fotoluminescência. / Pressure sensitive films based on photoluminescence technique.

Keth Rousbergue Maciel de Matos 20 May 2011 (has links)
O presente projeto tem como objetivo contribuir para o desenvolvimento de dispositivos para monitoração de pressão dinâmica do ar. Para isso, foram produzidos filmes sensíveis a pressão baseados na detecção de concentração de oxigênio por meio de processos de emissão fotoluminescente das moléculas de Azul de Metileno (MB) e Platina Octaetilporfirina (PtOEP). Nesse sentido, foi estudado o comportamento da emissão fotoluminescente dessas moléculas em interação com o gás de oxigênio. A concentração de oxigênio (do ar) sobre superfície sensível depende da pressão dinâmica de superfície. Desta forma, monitorando a fotoluminescência dos dispositivos submetidos a diferentes concentrações de oxigênio, pode-se determinar uma relação entre a pressão pontual da superfície analisada e a intensidade de emissão fotoluminescente do filme. Os dispositivos de monitoração de pressão dinâmica são constituídos de um filme de estado sólido contendo as moléculas sensíveis. Foram utilizados como substratos hospedeiros para o Azul de Metileno e para a Octaetilporfirina de Platina, os filmes de silício poroso oxidado e Poliestireno, respectivamente. É proposto um arranjo experimental que utiliza um fluorímetro para caracterizar as amostras produzidas e uma câmara de fluxo de gases. Os dispositivos apresentaram elevada sensibilidade e evidenciaram o potencial para desenvolvimento e integração de sensores baseados no silício poroso à microeletrônica. / This project aims to contribute to the development of devices for monitoring dynamic pressure of the air. In this sense, films were produced based on pressure-sensitive detection of oxygen concentration through processes of photoluminescence emission from the molecules of methylene blue (MB) and platinum octaethylporphyrin (PtOEP). Accordingly, it was studied the behavior of the photoluminescence emission of these molecules in interaction with the oxygen gas. The concentration of oxygen (of the air composition) on the sensitive surface depends on the surface dynamic pressure. Thus, monitoring the photoluminescence of the devices under different oxygen concentrations, it can be determined a relationship between the punctual pressure of the tested surface and the photoluminescence emission intensity of the film. The devices for monitoring dynamic pressure are made of a solid state film containing the sensitive molecules. Oxidized porous silicon and polystyrene films were used as hosts for the Methylene Blue and for the Platinum Octaethylporphyrin, respectively. It was proposed an experimental setup that uses a spectrofluorophotometer and a gas flow chamber to characterize the produced samples. The devices showed high sensitivity and potential for development and integration of the sensors based on porous silicon for microelectronics.
233

Estudo teórico de interações não covalentes entre complexos trinucleares de platina (II) e DNA

Paixão, Nathália Magalhães 20 February 2017 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-15T14:18:18Z No. of bitstreams: 1 nathaliamagalhaespaixao.pdf: 3549646 bytes, checksum: dfd913fd20520fb3cbfe42b45a3b6f5f (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T15:59:23Z (GMT) No. of bitstreams: 1 nathaliamagalhaespaixao.pdf: 3549646 bytes, checksum: dfd913fd20520fb3cbfe42b45a3b6f5f (MD5) / Made available in DSpace on 2017-05-17T15:59:23Z (GMT). No. of bitstreams: 1 nathaliamagalhaespaixao.pdf: 3549646 bytes, checksum: dfd913fd20520fb3cbfe42b45a3b6f5f (MD5) Previous issue date: 2017-02-20 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Câncer é um processo de crescimento e disseminação incontrolado de células e tem sido considerado como uma questão de saúde pública. Os compostos polinucleares de Platina (II) têm se mostrado muito promissores contra células cancerosas devido a interações mais rápidas e efetivas em comparação com os compostos mononucleares, como por exemplo, o complexo BBR3464. A partir disso, diversos estudos vêm sendo realizados com intuito de descrever os modos de interação de tais compostos. Este trabalho tem como objetivo fornecer um estudo teórico sistemático do complexo trinuclear de platina (II), AH78, através do uso de diferentes níveis de cálculo. Os compostos trinucleares de platina (II) estudados nesse trabalho não são capazes de formar ligações covalentes com o DNA, interagindo através da formação de grampos de fosfato, que são preferencialmente interações de hidrogênio e eletrostáticas. Dessa forma, este trabalho teve como motivação avaliar a interação dos complexos trinucleares de platina (II) não covalentes com o DNA por meio da formação de grampos de fosfato, analisadas através de modelos miméticos demonstrando presença de tais interações a partir de uma análise mais rápida e eficaz. Foram obtidas estruturas contendo uma fração de DNA que contém 6 pares de bases nitrogenadas e o complexo AH78, utilizando o método ONIOM, que comprovam a existência dos grampos de fosfato entre o complexo e o DNA. / Cancer is a process of uncontrolled growth and spread of cells and has now been considered a public health issue. Polynuclear Platinum (II) Complexes (PPCs) have shown very promising against cancer cells because of faster and more effective interactions compared to mononuclear compounds, such as the BBR3464 complex. From this, several studies have been carried out to describe the modes of interaction of such compounds. This work provides an extensive and systematic theoretical study of the platinum (II) trinuclear complex, AH78, using different base set functions for C, N and H atoms, including diffusive and polarization functions and different ECPs for platinum. The platinum (II) trinuclear compounds studied in this work are not able to form covalent bonds with DNA, interacting by the formation of phosphate bonds, which are preferably hydrogen type and electrostatic interactions. Thus, this work had the motivation to evaluate the interaction of non-covalent platinum (II) trinuclear complexes with DNA by means of the formation of phosphate clamps, analyzed using mimetic models, demonstrating that the presence of such interactions from a faster analysis is efficient. Structures containing a DNA fraction were obtained with six purine base pairs and AH78 complex using the ONIOM method, which demonstrate the existence of the phosphate clamps between the complex and the DNA.
234

Síntese, caracterização e estudo biológico de compostos de rutênio, platina, paládio e ouro com o ligante dicloridrato de N,N’-bis (tiofenil-2-metil) etano-1,2-diamina

Amaral, Thaeny Costa 23 February 2017 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-07-20T11:57:50Z No. of bitstreams: 1 thaenycostaamaral.pdf: 3993563 bytes, checksum: 62bc56f6ffb8386752008017f578a088 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-09T12:26:57Z (GMT) No. of bitstreams: 1 thaenycostaamaral.pdf: 3993563 bytes, checksum: 62bc56f6ffb8386752008017f578a088 (MD5) / Made available in DSpace on 2017-08-09T12:26:57Z (GMT). No. of bitstreams: 1 thaenycostaamaral.pdf: 3993563 bytes, checksum: 62bc56f6ffb8386752008017f578a088 (MD5) Previous issue date: 2017-02-23 / No presente trabalho foram descritas as sínteses e as caracterizações do ligante dicloridrato de N,N'-bis(tiofenil-2-metil)etano-1,2-diamina (BNHred.2HCl), dos seus complexos [RuCl2BNHred(PPh3)2], [PtCl2BNHred] e [PdCl2BNHred] e dos sais [BNHred.2H+][PtCl4] e [BNHred.2H+][Au(CN)2]2-. Os compostos foram caracterizados por análise elementar (C, H, N), técnicas espectroscópicas no IV, Raman e RMN (solução e estado sólido), difração de raios X (DRX) por policristais e cálculos de DFT. Para os complexos [PtCl2BNHred] e [PdCl2BNHred] os resultados obtidos pelas técnicas de caracterização corroboram que a coordenação ocorreu pelos átomos de nitrogênio do grupo NH e por dois íons cloretos formando complexos com estrutura quadrática. O complexo [RuCl2BNHred(PPh3)2] teve sua estrutura determinada por DRX por policristais onde foi encontrada a estrutura com geometria octaédrica, tendo o íon Ru(II) coordenado aos grupos NH, de forma quelato, duas PPh3 e dois íons cloreto. Os sais [BNHred.2H+][PtCl4] e [BNHred.2H+][Au(CN)2]2- também tiveram suas estruturas determinadas por DRX (policristais), onde o sal [BNHred.2H+][Au(CN)2]2- se cristaliza em um sistema cristalino ortorrômbico e grupo espacial Pnn2 e o sal [BNHred.2H+][PtCl4] cristaliza-se no sistema triclínico e grupo espacial P-1. Além desses compostos, também foi sintetizado e caracterizado o ligante dinitrato de N,N'-bis(tiofenil-2metil)etano-1,2-diamina (BNHred.2HNO3), no qual teve a estrutura cristalina determinada por DRX (policristais), pertencendo ao sistema cristalino monoclínico e grupo espacial P21/c. Testes biológicos contra Mycobacterium tuberculosis, de todos os compostos obtidos foram realizados, onde o sal [BNHred.2H+][Au(CN)2]2- apresentou o CIM90 de 2,31 mg/L. / The present work, syntheses and characterizations of the ligand N,N’-bis(tiophenyl-2methyl)ethane-1,2-diamino dichlorydrate (BNHred.2HCl), their [RuCl2BNHred(PPh3)2], [PtCl2BNHred] and [PdCl2BNHred] complexes and their [BNHred.2H+][PtCl4] and [BNHred.2H+][Au(CN)2]2- salts were described. The compounds were analyzed by elementare analysis (C, H and N), IR, Raman and NMR (in solution and solid state) spectroscopies as well by powder X ray diffraction and DFT calculations. The [PtCl2BNHred] and [PdCl2BNHred] complexes should be square planar geometry since ligand is coordinated by nitrogen atoms of the NH groups and the coordination sphere is completed by two chlorine ions. The octahedral [RuCl2BNHred(PPh3)2] complex structure was determined/refined by powder X ray diffraction where the Ru(II) ion is coordinated by ligand in chelate mode, also by two PPh3 molecules and by two chloride ions. The [BNHred.2H+][PtCl4] and [BNHred.2H+][Au(CN)2]2- salt structures were also solved by powder X ray diffraction. [BNHred.2H+][Au(CN)2]2- salt crystallizes in orthorhombic system and space group Pnn2, while the [BNHred.2H+][PtCl4] salt belongs to triclinic system and space group P-1. In addition, the ligand N,N’-bis(tiophenyl-2-methyl)ethane-1,2-diamino dinitrate (BNHred.2HNO3) was also synthetized and fully characterized. The BNHred.2HNO3 structure was obtained by powder X ray diffraction and presents a monoclinic crystalline system and space group P21/c. Biological tests against Mycobacterium tuberculosis of all the obtained compounds have been carried out, where the [BNHred.2H+][Au(CN)2]2- salt has been shown MIC90 at 2.31 mg/L.
235

Catalytic wet air oxidation of industrial wastewaters:oxidation of bisphenol A over cerium supported metal catalysts

Heponiemi, A. (Anne) 15 September 2015 (has links)
Abstract The large amounts of industrial wastewaters, contaminated by hazardous and toxic compounds together with ever tightening legislation, have challenged traditional wastewater treatment methods. Therefore, the development of discharge limits under, cost-effective and ecological wastewater treatment has become an essential concern. Catalytic water phase technologies are interesting alternatives for traditional wastewater treatment. Among them catalytic wet air oxidation (CWAO) has been used successfully in the management of various industrial effluents. However, the development of an active and stable catalyst for the severe reaction conditions of CWAO has proved truly challenging. The aim of this thesis was to study the activity and stability of laboratory prepared cerium supported metal catalysts in the catalytic wet air and wet peroxide oxidation of aqueous organic pollutants. Ru supported on Ce-Zr mixed oxides and commercial activated carbon as reference were used in CWAO and catalytic wet peroxide oxidation (CWPO) of surface plating industry wastewater. Ag/Ce-Zr and Pt/Ce-Ti catalysts were catalyzed CWAO of aqueous solution of bisphenol A (BPA). Both CWAO and CWPO improved the abatement of organic compounds from surface plating industry wastewater when comparing the non-catalytic experiments. Moreover, catalytic oxidation enhanced the biodegradability of organic matter in the wastewaters. According to the results, Pt/Ce-Ti catalysts performed with higher activity in CWAO of BPA than Ag/Ce-Zr catalysts and almost 100% removal of BPA was achieved. The leaching of active metal during oxidation experiments affected the activity of Ag/Ce-Zr catalysts. Moreover, CWAO of BPA was not a surface area specific reaction but the activity of catalysts was related to the chemisorbed oxygen content on the catalysts’ surface. The results of this thesis showed that cerium supported metal catalysts are active and stable catalysts in CWAO of BPA and also in the treatment of industrial wastewater. Therefore, these catalysts could be applied next to pilot scale applications. / Tiivistelmä Teollisuuden jätevedet sisältävät usein haitallisia ja myrkyllisiä yhdisteitä, joiden käsittely perinteisillä jäteveden käsittelymenetelmillä on hyvin haastavaa. Lisäksi alati kiristyvä ympäristölainsäädäntö asettaa omat vaatimuksensa jäteveden käsittelylle. Katalyyttiset vedenkäsittelymenetelmät ovat viime vuosina herättäneet paljon kiinnostusta. Yksi lupaavimmista tekniikoista on katalyyttinen märkähapetus, jota on käytetty sekä lukuisten malliaineiden että teollisten jätevesien käsittelyssä. Märkähapetuksen vaativissa reaktio-olosuhteissa aktiivisena säilyvän katalyyttimateriaalin kehittäminen on kuitenkin osoittautunut varsin haasteelliseksi. Väitöskirjatutkimuksen tavoitteena oli kehittää aktiivisia ja kestäviä ceriumpohjaisia katalyyttimateriaaleja märkähapetusreaktioon. Tutkimuksessa valmistettiin Ru-, Pt- ja Ag-katalyyttejä, jotka impregnoitiin Ce-Zr- ja Ce-Ti-sekaoksideille. Ru/Ce-Zr-katalyyttejä sekä kaupallista aktiivihiiltä vertailumateriaalina käytettiin pintakäsittelyteollisuuden jäteveden märkähapetuksessa ja märkäperoksidihapetuksessa. Bisfenoli A:n (BPA) vesiliuoksen märkähapetusta katalysoitiin sekä Ag/Ce-Zr- että Pt/Ce-Ti-katalyyteillä. Katalyyttisellä märkähapetuksella ja märkäperoksidihapetuksella pintakäsittelyteollisuuden jäteveden orgaanisten yhdisteiden konsentraatio väheni enemmän verrattuna ilman katalyyttiä suoritettuihin hapetuksiin. Lisäksi käsitellyn vesinäytteen biohajoavuusaste nousi eli jäteveden sisältämät orgaaniset yhdisteet olivat hapettuneet helpommin biohajoavaan muotoon. Pt/Ce-Ti-katalyytit olivat Ag/Ce-Zr-katalyyttejä aktiivisempia BPA:n märkähapetusreaktiossa. Pt-katalyyttisessä reaktiossa saavutettiin lähes 100 % reduktio BPA:n pitoisuudessa. Ag-katalyyttien aktiivisuuteen vaikutti hopean osittainen liukeneminen hapetettavaan liuokseen märkähapetusreaktion aikana. Lisäksi havaittiin, että BPA:n märkähapetusreaktiossa katalyytin aktiivisuus oli riippuvainen katalyyttipintaan kemiallisesti sitoutuneen hapen määrästä eikä niinkään katalyytin pinta-alasta. Väitöskirjatutkimuksessa saatujen tulosten perusteella valmistetut ceriumpohjaiset metallikatalyytit olivat aktiivisia ja kestäviä. Katalysoiduissa hapetusreaktiossa sekä BPA:n että pintakäsittelyteollisuuden jäteveden orgaaninen kuormitus pieneni. Siksi valmistettuja katalyyttimateriaaleja voitaisiin tutkia seuraavaksi pilotti-mittakaavan sovellutuksissa.
236

Deactivation of oxidation catalysts by sulphur and phosphorus in diesel and gas driven vehicles

Kärkkäinen, M.-L. (Marja-Liisa) 28 November 2017 (has links)
Abstract The combustion of fuels in motor vehicles is one of the most significant causes of air emissions. The use of oxidation catalysts in exhaust gas emission treatment can reduce hydrocarbons (HCs) and carbon monoxide (CO) emissions by more than 90%. Fuels and engine lubricants contain impurities like sulphur (S) and phosphorus (P), which can have a significant effect on the activity and durability of oxidation catalysts. This thesis aims at increasing the current knowledge of the deactivation phenomena caused by sulphur and phosphorus in diesel and natural/bio gas oxidation catalysts. Accelerated laboratory scale sulphur, phosphorus and thermal treatments in gas-phase conditions were carried out for alumina (Al2O3) based platinum (Pt) and platinum-palladium (PtPd) metallic monolith diesel and natural gas oxidation catalysts. In addition, a vehicle-aged natural gas oxidation catalyst and an engine-bench-aged diesel oxidation catalyst were studied and used as a reference for the laboratory-scale-aged catalysts. BET-BJH, FESEM, TEM, XPS and DRIFT were used as characterization techniques to determine changes on the catalysts. The effect of accelerated deactivation treatments on the catalyst activity was determined using laboratory scale measurements in CO, HC and nitric oxide (NO) oxidation. Sulphur and phosphorus were found to cause morphological and chemical changes on the studied catalysts. Sulphur was found to be adsorbed vertically throughout the entire catalyst support from the catalyst surface to the metallic monolith, while phosphorus accumulated on the surface region of the precious metal containing catalysts. Both, sulphur and phosphorus, slightly increased the average size of the precious metal particles size and are adsorbed onto the alumina by chemical bonds. In addition, a partial transformation from PdO to Pd and a change in the shape of the precious metal particles due to phosphorus were detected. Due to the detected structural and chemical changes on the catalysts, sulphur and phosphorus treatments reduced the catalytic activity of the studied diesel and natural-gas-oxidation catalysts. Correspondence between real and simulated ageing was found and thus the used accelerated laboratory scale aging method can be stated to be a good tool to simulate sulphur and phosphorus exposure. / Tiivistelmä Moottoriajoneuvot ovat merkittäviä ilmapäästöjen aiheuttajia. Hapetuskatalyyttejä käyttämällä hiilimonoksidi- ja hiilivetypäästöistä pystytään poistamaan yli 90 %. Polttoaineet ja voiteluaineet sisältävät epäpuhtauksia kuten rikkiä ja fosforia, jotka voivat merkittävästi heikentää hapetuskatalyyttien aktiivisuutta ja kestävyyttä. Väitöskirjan tavoitteena on tuottaa uutta tietoa rikin ja fosforin aiheuttamasta diesel- ja maakaasukatalyyttien deaktivoitumisesta. Metalliseen monoliittiin tuettuja alumiinioksidipohjaisia platina- ja palladiumkatalyytteja ikäytetiin tekemällä niille rikki-, fosfori- ja lämpökäsittelyjä. Maantieikäytettyä maakaasuhapetuskatalyyttiä ja moottoripenkki-ikäytettyä dieselhapetuskatalyyttiä käytettiin laboratorioikäytettyjen katalyyttien referensseinä. Ikäytyskäsittelyjen aiheuttamat muutokset analysoitiin BET-BJH-, FESEM-, TEM-, XPS- ja DRIFT-menetelmillä. Käsittelyjen vaikutus katalyyttien hiilimonoksidin, hiilivetyjen ja typenoksidien hapetusaktiivisuuteen tutkittiin laboratoriomittakaavan aktiivisuuslaitteella. Rikki ja fosfori aiheuttivat rakenteellisia ja kemiallisia muutoksia tutkittuihin katalyytteihin. Rikki adsorboitui koko tukiaineeseen (tukiaineen pinnalta pohjalle), kun taas fosfori adsorboitui vain pinnan alueelle. Sekä rikki että fosfori kasvattivat jalometallipartikkeleiden kokoa sekä muodostivat alumiinioksidin kanssa yhdisteitä. Lisäksi fosforikäsittelyjen havaittiin osittain pelkistävän PdO:n Pd:ksi ja muuttavan jalometallipartikkelien muotoa. Havaitut rikin ja fosforin aiheuttamat rakenteelliset sekä kemialliset muutokset laskivat diesel- ja maakaasukatalyyttien hapetusaktiivisuutta. Laboratorioikäytyksillä havaittiin olevan hyvä korrelaatio todellisissa olosuhteissa tehtyjen ikäytysten kanssa ja tästä syystä työssä käytetyn laboratoriomittakaavan ikäytysmenetelmän voidaan todeta olevan hyvä työkalu simuloimaan rikin ja fosforin aiheuttamaa deaktivoitumista.
237

Studium chování nanočástic platiny ve složkách životního prostředí / The study of behavior of platinum nanoparticles in environmental compartments

Berka, Michal January 2020 (has links)
Platinum nanoparticles pose a risk to environmental compartments. The aim of this diploma thesis is to conduct research on the influence of platinum nanoparticles in a wide range of concentrations on soil properties at different humidities. Specifically, it is about influencing the stability of water molecular bridges, the content of aliphatic crystallites, the retention capacity of water in the soil and the strength of water binding. Furthermore, the amount of nanoparticles sorbed on the soil was also measured. These indicators give us more information about the influence of platinum nanoparticles on evapotranspiration and soil deterioration. Methods of thermal analysis (differential scanning calorimetry) and optical methods (atomic absorption spectrometry) were used for these researches. The theoretical part of the work is devoted to a comprehensive introduction to platinum and its nanoparticles, as well as aqueous molecular bridges. It has been found that 200 nm platinum nanoparticles affect the strength of aqueous molecular bridges, have no effect on aliphatic crystallite content, have minimal effect on soil water retention, and that the water bond strength decreases due to platinum nanoparticles at high relative humidity. With 200 nm platinum nanoparticles, complete adsorption to soil occurs over the entire concentration range. With 3 nm nanoparticles, the soil is supersaturated at higher concentrations and larger amounts are not adsorbed. The results show that the larger the size of the platinum nanoparticles, the lower the negative effect on evapotranspiration and soil function itself.
238

Vysoce uspořádané tenké vrstvy oxidu kobaltu pro modelovou katalýzu / Highly ordered cobalt oxide thin films for model catalysis

Ronovský, Michal January 2020 (has links)
Hydrogen processing is becoming increasingly important not only in the production of electricity but also during its accumulation. One of the energy storage options are liquid organic hydrogen carriers (LOHC). The main drawback of LOHC is the need for a large amount of thermal energy to release molecular hydrogen. We can bypass this issue using heterogeneous catalysis by transferring hydrogen from LOHC to acetone and using the produced 2-propanol (IPA) in the fuel cell. This innovative strategy of getting electri- cal energy from LOHC can be potentially energetically neutral. In this work, we studied highly ordered Co3O4(111) model catalysts for IPA oxidation in the as-prepared state and enhanced with platinum (Pt) nanoparticles. Catalysts were prepared by Physical Vapour Deposition (PVD) and further investigated by means of Low Energy Electron Diffrac- tion (LEED), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Temperature Programmed Desorption (TPD). The nucleation process of Pt on the as-prepared Co3O4(111) surface was studied by depositing low amounts 0.04 and 0.13 monolayer (ML) of Pt, that create clusters as small as 2 or 3 atoms with no need for a special nucleation site. We have identified the formation of Pt-induced defects in the atomically flat cobalt oxide...
239

Stanovení obsahu platiny na území města Brna / Determination of platinum in Brno's agglomeration

Dvořák, Rostislav January 2014 (has links)
This thesis is focused on the determination of platinum in samples of road dust and soil by atomic absorption spectrometry. The theoretical part describes the basic physical and chemical properties of platinum, platinum function in automotive converters and its behavior in the environment. In the experimental section summarizes the methods used to decompositions samples, concentration of the analyte and the main results of the measurements.
240

Stanovení platinových kovů ve velkých městských aglomeracích / Determination of platinum group metals in great urban agglomerations

Ježek, Stanislav January 2016 (has links)
The aim of this thesis is the actual elaboration literature search concerning the issue of platinum group metals in the environment, determination of platinum and palladium in great urban agglomerations. It includes chemical and physical properties, occurrence and platinum and palladium cycle in the environment. It also contains methods for extraction and determination of platinum and palladium.

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