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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.
31

Automated Mineral Analysis of Mine Waste

Buckwalter-Davis, Martha 26 August 2013 (has links)
Mineral Liberation Analyzer (MLA) is an automated mineralogical system originally developed to characterize ore and mill feeds for the metallurgical processing industry. Its ability to quantitatively characterize solid and particulate material, including whole rock thin sections, waste rock, tailings, soil, and sediments, has led to increasing applications in other industries. The software uses back-scatter electron imagery and energy dispersive X-ray analysis to analyze each particle’s shape, size, and mineralogical information. Energy dispersive X-ray data are compared to a user-generated Mineral Reference Library consisting of known phases and corresponding EDS spectra to classify each particle. MLA is used in this study to provide quantitative assessments of mining-related environmental samples to answer questions regarding mineralogical controls on bioaccessibility, metal leaching/acid rock drainage potential, and anthropogenic influence. Six tailings samples from the New Calumet Mine in Quebec, Canada, were analyzed using MLA. Gastric Pb bioaccessibility testing and total metal content performed on these samples indicated that Pb bioaccessibility in the <250 micron size fraction was not directly correlated with the total Pb concentration. This suggested that there were mineralogical and/or physical controls on bioaccessibility. MLA was used to quantify the relative proportions of cerussite, a highly bioaccessible Pb carbonate, and galena, a lower bioaccessibility Pb sulfide. Liberation and particle size were also analyzed as controls on bioaccessibility. Sample GD-VEG1 (highest bioaccessibility) has the highest ratio of cerussite to galena, the smallest particle size, and the most liberated Pb-bearing particles. The New Calumet tailings were also analyzed using static testing, a suite of laboratory tests used by environmental scientists and mine operators to operationally define acid rock drainage and metal leaching potential. Modal mineralogy obtained from MLA analysis was used to calculate neutralization potential (NP) and acid potential (AP), taking into account the presence of iron carbonate minerals and iron-bearing sulfides other than pyrite. Results are within several units of those obtained by static testing. Two Ni-impacted soil samples collected from the region of Kalgoorlie, Australia were characterized using MLA. Previous studies had focused on bioaccessibility and sequential extraction testing and minor mineralogical work. Preliminary XANES characterization conflicted with mineralogy predicted from sequential extraction and EMPA and MLA were used to quantitatively characterize major Ni-bearing phases and resolve previous discrepancies. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2013-08-24 08:13:18.722
32

Tillämpning av begreppet hållbar utveckling från läroplan till läromedel

Tani, Stefano January 2017 (has links)
Med utgångspunkt i FN:s årtionde för utbildning i hållbar utveckling 2005-2014 har begreppet hållbar utveckling vävts in i gymnasieskolans styrdokument. Uppsatsen undersöker vad som händer med begreppet hållbar utveckling när det översätts från läro- och ämnesplaner till läroböcker för gymnasieskola. Fyra olika ämnen ingår i studien: företagsekonomi, geografi, naturkunskap och samhällskunskap. Undersökningen bygger på en kvalitativ innehållsanalys gjord på fyra olika läroböcker, en i varje ämne. Analysen syftar till att visa huruvida begreppet används samt att mäta hur begreppet används i böckerna, med hjälp av en skala som avspeglar om hållbar utveckling gestaltas utifrån sin ”svaga” eller ”starka” variant. Resultatet tyder på att begreppet tillämpas i läroböckerna på ett ojämnt sätt. Böckerna i geografi och samhällskunskap ägnar lite plats åt begreppet och det nämns inte ens en gång. Böckerna i företagsekonomi och naturkunskap ägnar mer plats åt begreppet, nämner det och anknyter det dessutom bättre till respektive ämne. Beträffande gestaltningen är den starka varianten av hållbar utveckling något vanligare och till och med dominant i böckerna i geografi och naturkunskap. Dessa ämnesskillnader kan förklaras med olika faktorer: påverkan av ämnenas egna traditioner, begreppets grundläggande tvetydighet samt läro- och ämnesplanernas benägenhet att bli spänningsfält för olika kunskapssyner. Det är dock svårare att förklara varför två böcker (geografi och naturkunskap) använder en starkare variant av begreppet men inte de andra två böckerna (företagsekonomi och samhällskunskap).
33

The effect of latent fingerprint processing on the recovery of gunshot primer residue particles from latex gloves

Jenquine, Kelsie Lynn 12 June 2019 (has links)
Gunshot primer residue (P-GSR) is released from the openings of a firearm when it is discharged12,13. P-GSR is made of microscopic particles that are considered characteristic of being derived from firearm ammunition when composed of barium (Ba), lead (Pb), and antimony (Sb) and have the correct morphology4. Morphology describes the shape of the P-GSR particle, which can be spherical, irregularly shaped, and must be non-crystalline. Forensic labs are commonly requested to test for the presence of P-GSR on evidential items, such as hands, clothing, vehicles, and gloves, in order to provide circumstantial evidence showing that they were, in some way, possibly involved with a shooting. Occasionally these evidential items are also expected to undergo fingerprint processing to potentially link someone to a crime. Latex gloves are often utilized in the commission of a crime with the impression that fingerprints cannot be left behind, however latent prints can often be developed on this non-porous material. Due to the evidential value of fingerprints and in order to ensure that potential prints are not damaged during P-GSR collection, latent print development is routinely performed first. Considering that P-GSR particles are easily dislodged, it is possible that some loss of P-GSR may occur during latent print processing. The purpose of this study was to evaluate the effect of processing a non-porous item for latent fingerprints on the subsequent recovery and detection of P-GSR. Latex gloves were worn during the discharge of either a pistol or a revolver and then processed for latent prints by undergoing cyanoacrylate fuming followed by either white powder or yellow dye. The latex gloves were then sampled for P-GSR using aluminum stubs containing an adhesive coating which were dabbed over the gloves until they loss their tackiness. The stubs were then carbon coated using a Denton Vacuum Desk IV in order to prevent charging in the analytical instrument. Utilizing a JEOL JSM-6460LV Scanning Electron Microscope (JEOL USA Inc., Peabody, MA coupled with an EDAX Apollo X Analyzer (EDAX Inc., Mahwah, NJ) and EDAX Genesis GSR Software, the stubs were processed for three-component particles characteristic of P-GSR. It was determined that P-GSR can still be recovered on latex gloves after undergoing latent print processing involving cyanoacrylate fuming followed by either white powder or yellow dye processing. Three-component particles were found on both the interior and exterior of the latex gloves after being processed for latent prints. On average, 33 P-GSR particles were found on the exterior of the gloves and four P-GSR particles were found on the interior of the gloves. Although significantly less were found on the interior of the gloves (<10), it is recommended that both sides of gloves be stubbed when collecting P-GSR for the greatest chances of collecting three-component particles if they are in fact present on a pair of gloves. Although more particles were found on the gloves that were not processed for latent prints, a sufficient number of particles (≥3 particles) were consistently found on the latex gloves after undergoing latent print processing to provide a positive P-GSR result according to the Massachusetts State Police Crime Lab guidelines for P-GSR analysis. Therefore, this research shows that latex gloves can first be processed for latent prints and then subsequently be processed for P-GSR effectively in order to try and obtain both forms of evidence for a case.
34

Estudo de ?ons cobre no mecanismo de forma??o de complexo com resveratrol em modelo de c?lulas MCF-7

Volkart, Priscylla Andrade 27 March 2017 (has links)
Submitted by PPG Biologia Celular e Molecular (bcm@pucrs.br) on 2017-07-25T18:53:17Z No. of bitstreams: 1 PRISCYLLA_ANDRADE_VOLKART_DIS.pdf: 1703523 bytes, checksum: 625ed4371e92d211496ba44a5d264d21 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-07-26T14:20:44Z (GMT) No. of bitstreams: 1 PRISCYLLA_ANDRADE_VOLKART_DIS.pdf: 1703523 bytes, checksum: 625ed4371e92d211496ba44a5d264d21 (MD5) / Made available in DSpace on 2017-07-26T14:27:43Z (GMT). No. of bitstreams: 1 PRISCYLLA_ANDRADE_VOLKART_DIS.pdf: 1703523 bytes, checksum: 625ed4371e92d211496ba44a5d264d21 (MD5) Previous issue date: 2017-03-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The redox-active chemical properties of trace element copper make it an essential cofactor for several cellular mechanisms, as for ROS production. Polyphenols have been used in the pro-oxidant mechanism of action of interaction with endogenous Cu (II) ions for the production of reactive oxygen species in excess as a treatment for malignancies, leading to apoptosis. This work studied Cu (II) ions in the complex formation mechanism with Resveratrol in MCF-7 cells model. We analyzed the selectivity of Resveratrol in relation to the cupric metal ion using HPLC (High-Performance Liquid Chromatography) and the formation of the compound Resveratrol-Copper through UV-VIS (Ultra-Violet Visible Spectrophotometry). We analyzed the cellular morphology and location of the metal ion by MET-EDS (Electronic Transmission microscopy with Dispersive X-ray Spectroscopy). Cell death by apoptosis and quantification of ROS in said cell line with copper enrichment and treated with Resveratrol was made by flow cytometry. The results show the selectivity of the polyphenol compound by copper ion as well as the formation of the complex Resveratrol-Copper in extracellular conditions, however even with verification of endogenous copper accumulation in physiological conditions in vitro, the formation of that complex did not occur because there was no production of ROS and therefore, no cell death. In short, our research reveals that for in vitro conditions for the MCF-7 line, there's no Resveratrol-Copper complex formation as observed in sub-lethal quantities of chemically enriched cells with CuSO4 and treated with Resveratrol. / As propriedades qu?micas redox-ativas do oligoelemento cobre o tornam cofator essencial para diversos mecanismos celulares como o de produ??o de ROS. Polifen?is v?m sendo utilizados no mecanismo de a??o pr?-oxidante de intera??o com ?ons Cu (II) end?geno para a produ??o dessas esp?cies oxig?nio reativas em excesso como tratamento de malignidades, levando a apoptose. O presente trabalho estudou os ?ons Cu (II) no mecanismo de forma??o do complexo com Resveratrol em modelo de c?lulas MCF-7. Analisamos a seletividade do Resveratrol frente ao ?on met?lico c?prico utilizando CLAE (Cromatografia L?quida de Alta Efici?ncia) e verificou-se a forma??o do complexo Resveratrol-Cobre por meio de UV-VIS (Espectrofotometria de Ultra-Violeta Vis?vel). Analisou-se a morfologia celular e localiza??o do ?on met?lico por MET-EDS (Microscopia de Transmiss?o Eletr?nica com Espectroscopia Dispersiva de Raios-X). Morte celular por apoptose e quantifica??o de ROS na linhagem enriquecida com cobre e tratadas com Resveratrol foi feita por Citometria de Fluxo. Os resultados mostram a seletividade do composto polifen?lico pelo ?on cobre bem como a forma??o do complexo Resveratrol-Cobre em condi??es extracelulares, por?m mesmo com a verifica??o de ac?mulo de cobre end?geno, em condi??es fisiol?gicas in vitro n?o foi constatada a forma??o do referido, pois n?o houve forma??o de ROS e morte celular conseguinte. Em suma, Nossa pesquisa revela que em condi??es in vitro para a linhagem MCF-7, n?o h? forma??o de complexo Resveratrol-Cobre como observado quimicamente em quantidades sub-letais de c?lulas enriquecidas com CuSO4 e tratadas com Resveratrol.
35

Aproveitamento de embalagens cartonadas em compósito de polietileno de baixa densidade. / Re-use of carton packages in low density polyethylene composites.

Borges, Daliana Gomes 05 September 2007 (has links)
A produção de materiais plásticos tem se elevado para 169 milhões de toneladas no mundo, no ano de 2003. Uma parte considerável destes polímeros sintéticos, 36% na Europa são destinados ao setor de embalagens. Estas matérias primas são utilizadas por um período de tempo bastante curto e geram um volume de descartes importante. Mesmo com um desenvolvimento considerável de linhas de gestão dos descartes, seu tratamento e sua eliminação colocam ainda problemas provenientes da dificuldade em reutilizar tais embalagens na forma em que são geradas, seja pelo estado de limpeza em que são descartadas, seja pela composição multi-material que é utilizada para sua produção. O presente trabalho busca o reaproveitamento de Embalagens Cartonadas pós-consumo como reforço em compósito com Polietileno de baixa densidade para i) maximizar o teor de ELV empregada no compósito e ii) melhorar o aspecto visual do compósito por meio de incorporação de concentrado de cores e corantes. Por meio do processo de extrusão, preparou-se o compósito na forma granulada. O material granulado foi moldado por injeção para obtenção dos corpos-de-prova para ensaios de tração. As propriedades viscosimétricas do compósito foram avaliadas por meio do Índice de Fluidez e a morfologia do compósito foi avaliada por meio de microscopia eletrônica de varredura e espectroscopia de energia dispersiva de raio X. Nas condições do trabalho pode-se afirmar que o teor de Embalagem Cartonada que apresenta o melhor conjunto de propriedades de tração está entre 20 e 25% (p/p) no compósito; a utilização de concentrado de cor para melhoria do aspecto visual do compósito não tem influência no conjunto de propriedades de tração do mesmo. / Plastics materials production has increased to 169 million tons in the world in 2003. A great part of these synthetic polymers, it means 36% in Europe are used in packaging applications. These raw materials are used for a short time and produces a great volume of residues. Even with a great development of residues management, its treatments and elimination causes several problems due to difficulty in reuse these packages as its were discarted or the state of dirtiness in which they are discarted or even by the composition multi-material of these packages. This work has as a goal the reuse of Carton Packages (CP) post-use as a reinforcement in a Low Density PolyEthylene (LDPE), to i) maximize the content of CP in the composite and ii) improve the composite visual aspect by means of color masterbatches. With aid of extrusion process, the granuleted composite was prepared. These granulated was moulded by injection to obtain test specimens for mechanical tests. Composites viscosimetric proprierties and morphology were evaluated by means of Melt Index and Scanning Electronic Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). In the work conditions it can be postulate that the best content of CP in the composite that gives the best mechanical properties is between 20 and 25% (w/w); the use of color masterbatches for improve the composite visual aspects has no influence over mechanical properties.
36

Thermobaromètrie des phylloscilicates dans les séries naturelles : conditions de la diagénèse et du métamorphisme de bas degré / Thermobarometry of phyllosilicates in natural fields : diagenesis and low-grade metamorphism conditions

Bourdelle, Franck 22 June 2011 (has links)
Les illites et les chlorites sont des minéraux ubiquistes dans la plupart des roches diagénétiques. Leurs compositions chimiques dépendent des conditions physiques subies (pression, P ; température, T) et de la composition de l’encaissant (e.g. Vidal et al., 1999 ; Parra et al., 2002a, 2002b). Ces minéraux peuvent donc potentiellement être de très bons marqueurs de l’histoire de l’enfouissement, et sont à la base de nombreuses méthodes empiriques ou thermodynamiques d’estimation des conditions P-T.Une compilation de données naturelles et la comparaison des thermobaromètres existants ont permis d’établir leurs limitations respectives. Pour s’en affranchir, un nouveau modèle ordonné de solution solide pour les chlorites a été développé, qui rend compte des forts contenus en silicium observés dans les chlorites naturelles de basses températures. La calibration de ce nouveau thermobaromètre sur des domaines géologiques variés de BT-BP a été testée sur des analyses de chlorites naturelles de la Gulf Coast (Texas) au pic de température (où les données P-T ont été mesurées in situ) et montre d’excellents résultats. Concernant les illites, le modèle thermodynamique le plus abouti (Dubacq et al., 2010) a également été testé de manière à estimer sa précision. L’étude a été complétée par la quantification de l’influence du fer ferrique. Les analyses chimiques utilisées ont été obtenues grâce à un protocole analytique à haute résolution spatiale. Alliant FIB et MET-EDS, ce protocole a permis une étude microtexturale et chimique fine des chlorites et des illites. Il en ressort que ces minéraux possèdent une diversité intracristalline dans leurs compositions et que la zonation chimique résultante apparaît comme une potentielle source d’erreurs dans la calibration des thermobaromètres, tout en permettant d’envisager la notion d’équilibre à l’échelle locale.Cette approche a été utilisée pour quantifier les trajets P-T d’unités géologiques des Alpes de Glarus. Ces résultats, comparés à ceux obtenus avec des méthodes thermobarométriques conventionnelles, donnent une bonne image des processus d’enfouissement et d’exhumation des roches de basse température. Ainsi, il apparaît que chaque composition enregistre une portion du chemin P-T rétrograde. D’une manière générale, chaque zone d’un même cristal renvoie à une partie de l’histoire de la roche. / Illite and chlorite are ubiquitous in most diagenetic rocks. Their chemical compositions are sensitive to thermobarometric conditions (pressure, P; temperature, T) and the bulk composition (e.g. Vidal et al., 1999; Parra et al., 2002a, 2002b). These minerals can be good indicators of burial history, and are the basis of several empiric or thermodynamic methods to estimate P-T conditions. A compilation of natural data and the comparison of existing thermobarometers allowed to establish their limitations. To circumvent it, an ordered model of solid solution for chlorites was developed which considers Si-rich low-T compositions. The calibration of this new thermobarometer on various LT-LP geologic fields was tested on natural chlorites analysis of Gulf Coast (Texas) at metamorphic peak, and gives accurate results. Concerning illites, the thermodynamic model of Dubacq et al. (2010) was also tested to estimate its precision. The study was completed by the quantification of the Fe3+ effects. Chemical analyses were obtained by an analytical protocol with high spatial resolution. Combining FIB and EDX-TEM, this protocol allowed an accurate microstructural study of chlorites and illites. These minerals have an intracristalline diversity of their chemical composition. The resulting chemical zonation is a potential error in calibration of thermometers, but allowed consideration of local equilibrium.This approach was used to quantify the P-T path of geologic units in Alps (near Glarus). These results, compared to results of conventional thermobarometers, give a good representation of burial and exhumation process for low-T rocks. Thus, the chemistry records a part of retrograde P-T path and each part of a crystal zoning corresponds to a part of rocks history.
37

Elemental Characterization of Printing Inks and Strengthening the Evaluation of Forensic Glass Evidence

Corzo, Ruthmara 29 May 2018 (has links)
Improvements in printing technology have exacerbated the problem of document counterfeiting, prompting the need for analytical techniques that better characterize inks for forensic analysis. In this study, 319 printing inks (toner, inkjet, offset, and intaglio) were analyzed directly on the paper substrate using Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). As anticipated, the high sensitivity of LA-ICP-MS resulted in excellent discrimination (> 99%) between ink samples originating from different sources. Moreover, LA-ICP-MS provided ≥ 90% correct association for ink samples originating from the same source. SEM-EDS resulted in good discrimination for toner and intaglio inks (> 97%) and excellent correct association (100%) for all four ink types. However, the technique showed limited utility for the discrimination of inkjet and offset inks. A searchable ink database, the Forensic Ink Analysis and Comparison System (FIACS), was developed in order to provide a tool that allows the analyst to compare a questioned ink sample to a reference population. The FIACS database provided a correct classification rate of 94-100% for LA-ICP-MS and 67-100% for SEM-EDS. An important consideration in forensic chemistry is the interpretation of the evidence. Typically, a match criterion is used to compare the known and questioned sample. However, this approach suffers from several disadvantages, which can be overcome with an alternative approach: the likelihood ratio (LR). Two LA-ICP-MS glass databases were used to evaluate the performance of the LR: a vehicle windshield database (420 samples) and a casework database (385 samples). Compared to the match criterion, the likelihood ratio led to improved false exclusion rates (< 1.5%) and similar false inclusion rates (< 1.0%). In addition, the LR limited the magnitude of the misleading evidence, providing only weak support for the incorrect proposition. The likelihood ratio was also tested through an inter-laboratory study including 10 LA-ICP-MS participants. Good correct association rates (94-100%) were obtained for same-source samples for all three inter-laboratory exercises. Moreover, the LR showed a strong support for an association. Finally, all different-source samples were correctly excluded with the LR, resulting in no false inclusions.
38

Thermobaromètrie des phylloscilicates dans les séries naturelles : conditions de la diagénèse et du métamorphisme de bas degré

Bourdelle, Franck 22 June 2011 (has links) (PDF)
Les illites et les chlorites sont des minéraux ubiquistes dans la plupart des roches diagénétiques. Leurs compositions chimiques dépendent des conditions physiques subies (pression, P ; température, T) et de la composition de l'encaissant (e.g. Vidal et al., 1999 ; Parra et al., 2002a, 2002b). Ces minéraux peuvent donc potentiellement être de très bons marqueurs de l'histoire de l'enfouissement, et sont à la base de nombreuses méthodes empiriques ou thermodynamiques d'estimation des conditions P-T.Une compilation de données naturelles et la comparaison des thermobaromètres existants ont permis d'établir leurs limitations respectives. Pour s'en affranchir, un nouveau modèle ordonné de solution solide pour les chlorites a été développé, qui rend compte des forts contenus en silicium observés dans les chlorites naturelles de basses températures. La calibration de ce nouveau thermobaromètre sur des domaines géologiques variés de BT-BP a été testée sur des analyses de chlorites naturelles de la Gulf Coast (Texas) au pic de température (où les données P-T ont été mesurées in situ) et montre d'excellents résultats. Concernant les illites, le modèle thermodynamique le plus abouti (Dubacq et al., 2010) a également été testé de manière à estimer sa précision. L'étude a été complétée par la quantification de l'influence du fer ferrique. Les analyses chimiques utilisées ont été obtenues grâce à un protocole analytique à haute résolution spatiale. Alliant FIB et MET-EDS, ce protocole a permis une étude microtexturale et chimique fine des chlorites et des illites. Il en ressort que ces minéraux possèdent une diversité intracristalline dans leurs compositions et que la zonation chimique résultante apparaît comme une potentielle source d'erreurs dans la calibration des thermobaromètres, tout en permettant d'envisager la notion d'équilibre à l'échelle locale.Cette approche a été utilisée pour quantifier les trajets P-T d'unités géologiques des Alpes de Glarus. Ces résultats, comparés à ceux obtenus avec des méthodes thermobarométriques conventionnelles, donnent une bonne image des processus d'enfouissement et d'exhumation des roches de basse température. Ainsi, il apparaît que chaque composition enregistre une portion du chemin P-T rétrograde. D'une manière générale, chaque zone d'un même cristal renvoie à une partie de l'histoire de la roche.
39

Qualitative and Quantitative Analysis of Biodiesel Deposits Formed on a Hot Metal Surface

Westberg, Emilie January 2013 (has links)
This thesis aims to investigate the formation of deposits from thermally degraded biodiesel on a hot metal surface under the influence of sodium or copper contaminations. Biodiesel or Fatty Acid Methyl Esters (FAMEs) is a widely utilized biofuel with the potential to replace fossil fuels, however, issues regarding the thermal and oxidative stability prevent the progress of biodiesel for utilization as vehicle fuel. The thermal degradation of biodiesel causes formation of deposits often occurring in the fuel injectors, which could result in reduced engine efficiency, increased emissions and engine wear. However, still have no standard method for evaluation of a fuels’ tendency to form deposits been developed. In this study biodiesel deposits have been formed on aluminum test tubes utilizing a Hot Liquid Process Simulator (HLPS), an instrument based on the principle of the Jet Fuel Thermal Oxidation Tester (JFTOT). Quantitative and qualitative analyses have been made utilizing an array of techniques including Scanning Electron Microscopy (SEM), Gas Chromatography Mass Spectrometry (GCMS) and Attenuated Total Reflectance Fourier Transform Infrared Spectrometry (ATR-FTIR). A multi-factorial trial investigating the effects of sodium hydroxide and copper contaminations at trace levels and the impact of a paraffin inhibitor copolymer additive on three different FAME products, two derived from rapeseed oil and one from waste cooking oil as well as a biodiesel blend with mineral diesel, was conducted.The results exhibited that FAMEs are the major precursor to deposit formation in diesel fuel. The SEM analyses exploited the nature of FAME deposits forming porous structures on hot metal surfaces. Sodium hydroxide proved to participate in the deposit formation by forming carboxylic salts. However, the copper contamination exhibited no enhancing effect on the deposits, possibly due to interference of the blank oil in which copper was received. The paraffin inhibitor functioning as a crystal modifier had significant reducing effect on the deposit formation for all biodiesel samples except for the FAME product derived from waste cooking oil. Further studies are needed in order to investigate the influence of glycerin and water residues to the biodiesel deposit formation. Mechanisms involving oxidative or thermal peroxide formation, polymerization and disintegration have been suggested as degradation pathways for biodiesel. The involvement of oxidation intermediates, peroxides, was confirmed by the experiments performed in this thesis. However, the mechanisms of biodiesel deposit formation are complex and hard to study as the deposits are seemingly insoluble. Nevertheless, ATR-FTIR in combination with JFTOT-processing has potential as standard method for evaluation of deposit forming tendencies of biodiesel.
40

Thermal Stability of Arc Evaporated ZrCrAlN

Syed, Muhammad Bilal January 2012 (has links)
This research explores the thermal stability of ZrCrAlN material system. For this purpose fourteen different compositions of ZrCrAlN coatings were deposited onto tungsten carbide substrates by using reactive cathodic arc evaporation. These compositions were further annealed at 800oC, 900oC, 1000oC and 1100oC temperatures. EDS was employed to specify the compositions. The crystal structure of the coatings were analysed by XRD, and the hardness of these coatings was determined by Nanoindentation. The experimental findings reported a significant age hardening of Zr0.16Cr0.12Al0.72N and a delayed h-AlN formation in Zr0.07Cr0.40Al0.52N. ZrCrAlN was thus proved to be thermally stable. / Multifilms,A4:2 Growth and characterization of Multicomponent Nitrides by Magnetron Sputtering and Arc evaporation

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