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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.
51

Exploring nanoscale properties of organic solar cells

Mönch, Tobias 30 November 2015 (has links) (PDF)
The demand for electrical energy is steadily increasing. Highly efficient organic solar cells based on mixed, strongly absorbing organic molecules convert sunlight into electricity and, thus, have the potential to contribute to the worlds energy production. The continuous development of new materials during the last decades lead to a swift increase of power conversion efficiencies (PCE) of organic solar cells, recently reaching 12%. Despite these breakthroughs, the usage of highly complex organic molecules blended together to form a self-organised absorber layer results in complicated morphologies that are poorly understood. However, the morphology has a tremendous impact on the photon-to-electron conversion, affecting all processes ranging from light absorption to charge carrier extraction. This dissertation studies the role of phase-separation of the self-organised thin film blend layers utilized in organic solar cells. On the molecular scale, we manipulate the phase-separation, using different molecule combinations ranging from the well-known ZnPc:C 60 blend layers to highly efficient oligothiophene:C60 blend layers. On the macroscopic scale, we shape the morphology by depositing the aforementioned blend layers on differently heated substrates (in-vacuo substrate temperature, Tsub). To characterise the manufactured blend layers, we utilize high resolution microscopy techniques such as photoconductive atomic force microscopy, different electron microscopic techniques, X-ray microscopy etc., and various established and newly developed computational simulations to rationalise the experimental findings. This multi-technique, multi-scale approach fulfils the demands of several scientific articles to analyse a wide range of length scales to understand the underlying optoelectronic processes. Varying the mixing ratio of a ZnPc:C60 blend layer from 2:1 to 6:1 at fixed in vacuo substrate temperature results in a continuous increase of surface roughness, decrease of short-circuit current, and decrease of crystallinity. Additionally performed density functional theory calculations and 3D drift-diffusion simulations explain the observed crystalline ZnPc nanorod formation by the presence of C60 in the bulk volume and the in turn lowered recombination at crystalline ZnPc nanorods. Moving to oligothiophene:C60 blend layers used in highly efficient organic solar cells deposited at elevated substrate temperatures, we find an increase of phase-separation, surface roughness, decrease of oligothiophene-C60 contacts, and reduced disorder upon increasing Tsub from RT (PCE=4.5%) to 80 °C (PCE=6.8%). At Tsub =140 °C, we observe the formation of micrometer-sized aggregates on the surface resulting in inhomogeneous light absorption and charge carrier extraction, which in turn massively lowers the power conversion efficiency to 1.9%. Subtly changing the molecular structure of the oligothiophene molecule by attaching two additional methyl side chains affects the thin film growth, which is also dependent on the substrate type. In conclusion, the utilized highly sensitive characterisation methods are suitable to study the impact of the morphology on the device performance of all kinds of organic electronic devices, as we demonstrate for organic blend layers. At the prototypical ZnPc:C60 blend, we discovered a way to grow ZnPc nanorods from the blend layer. These nanorods are highly crystalline and facilitate a lowered charge carrier recombination which is highly desirable in organic solar cells. The obtained results at oligothiophene: C60 blends clearly demonstrate the universality of the multi-technique approach for an in-depth understanding of the fragile interplay between phase-separation and phase-connectivity in efficient organic solar cells. Overall, we can conclude that both molecular structure and external processing parameters affect the morphology in manifold ways and, thus, need to be considered already at the synthesis of new materials.
52

Kostní implantáty na bázi železa / Bones implants based on Fe

Hávová, Mariana January 2016 (has links)
This thesis refers to Fe-based biodegradable materials and their potencial aplications in medicine, especially as temporary bone implants. This work generaly summaries aplications of biomaterial in medicine with more interest kept on biodegradable materials and their in-vivo corrosion. The experimental part refers to conduction of porous Fe-based materials with silica addition. The structure of prepared specimens is identified by EDX and XRD analysis. The imersion test and electrochemical studies were conducted to observe corrosion behaviour with respect to different concentration of silica. Potenciodynamic curves were obtained to determine corrosion potencial and corrosion current density of prepared samples.
53

Exploring nanoscale properties of organic solar cells

Mönch, Tobias 19 November 2015 (has links)
The demand for electrical energy is steadily increasing. Highly efficient organic solar cells based on mixed, strongly absorbing organic molecules convert sunlight into electricity and, thus, have the potential to contribute to the worlds energy production. The continuous development of new materials during the last decades lead to a swift increase of power conversion efficiencies (PCE) of organic solar cells, recently reaching 12%. Despite these breakthroughs, the usage of highly complex organic molecules blended together to form a self-organised absorber layer results in complicated morphologies that are poorly understood. However, the morphology has a tremendous impact on the photon-to-electron conversion, affecting all processes ranging from light absorption to charge carrier extraction. This dissertation studies the role of phase-separation of the self-organised thin film blend layers utilized in organic solar cells. On the molecular scale, we manipulate the phase-separation, using different molecule combinations ranging from the well-known ZnPc:C 60 blend layers to highly efficient oligothiophene:C60 blend layers. On the macroscopic scale, we shape the morphology by depositing the aforementioned blend layers on differently heated substrates (in-vacuo substrate temperature, Tsub). To characterise the manufactured blend layers, we utilize high resolution microscopy techniques such as photoconductive atomic force microscopy, different electron microscopic techniques, X-ray microscopy etc., and various established and newly developed computational simulations to rationalise the experimental findings. This multi-technique, multi-scale approach fulfils the demands of several scientific articles to analyse a wide range of length scales to understand the underlying optoelectronic processes. Varying the mixing ratio of a ZnPc:C60 blend layer from 2:1 to 6:1 at fixed in vacuo substrate temperature results in a continuous increase of surface roughness, decrease of short-circuit current, and decrease of crystallinity. Additionally performed density functional theory calculations and 3D drift-diffusion simulations explain the observed crystalline ZnPc nanorod formation by the presence of C60 in the bulk volume and the in turn lowered recombination at crystalline ZnPc nanorods. Moving to oligothiophene:C60 blend layers used in highly efficient organic solar cells deposited at elevated substrate temperatures, we find an increase of phase-separation, surface roughness, decrease of oligothiophene-C60 contacts, and reduced disorder upon increasing Tsub from RT (PCE=4.5%) to 80 °C (PCE=6.8%). At Tsub =140 °C, we observe the formation of micrometer-sized aggregates on the surface resulting in inhomogeneous light absorption and charge carrier extraction, which in turn massively lowers the power conversion efficiency to 1.9%. Subtly changing the molecular structure of the oligothiophene molecule by attaching two additional methyl side chains affects the thin film growth, which is also dependent on the substrate type. In conclusion, the utilized highly sensitive characterisation methods are suitable to study the impact of the morphology on the device performance of all kinds of organic electronic devices, as we demonstrate for organic blend layers. At the prototypical ZnPc:C60 blend, we discovered a way to grow ZnPc nanorods from the blend layer. These nanorods are highly crystalline and facilitate a lowered charge carrier recombination which is highly desirable in organic solar cells. The obtained results at oligothiophene: C60 blends clearly demonstrate the universality of the multi-technique approach for an in-depth understanding of the fragile interplay between phase-separation and phase-connectivity in efficient organic solar cells. Overall, we can conclude that both molecular structure and external processing parameters affect the morphology in manifold ways and, thus, need to be considered already at the synthesis of new materials.
54

Magma-Carbonate Interaction and CO2 Release: A Case Study from Carlingford Igneous Centre, Ireland / Magma-karbonat-interaktion och CO2-utsläpp: En studie från Carlingford Igneous Centre, Irland

Lagrosen, Emelie January 2020 (has links)
Magma which intrudes into carbonate rich crust, interacts with the carbonate in several ways, for example by contact metamorphism and formation of marble or by metasomatism resulting in calc-silicate skarn. These processes release volatiles, such as CO2, from the carbonate and might thus cause climate change. One volcanic complex where the intrusions and their surrounding metamorphic aureole are well exposed and therefore convenient for investigation of magma-carbonate interaction is the Carlingford Igneous Centre in NE of Ireland. The complex is dominated by a gabbro lopolith and a microgranite ring dyke, which intruded into limestone and meta-siltstone at around 62-60 Ma. The purpose of this study is to investigate the extent of magma-carbonate interaction and assess the amount of CO2 which could have been released from the aureole at Carlingford. This is done by analysing major and trace elements as well as carbon and sulphur content in skarn and marble samples from a transect along the calc-silicate metamorphic aureole. The analytical methods used are SEM- EDX, XRF, LA-ICP-MS and carbon and sulphur analyses. The CO2 release is calculated by comparing the carbon and CO2 content in the skarn and marble samples with that in the unmetamorphosed limestone. The results show that the skarn has experienced a strong interaction with the magma, as it contains several high-grade minerals, such as wollastonite, vesuvianite and pyrope, and has lost almost all its carbon. The extent of interaction and amount of CO2 release is generally much lower in the marble, even though a few marble samples show a strong interaction and a high degree of degassing. On the other hand, the amount of marble in the aureole turns out to be significantly higher than the amount of skarn (70-90% compared to 10-30%). The total mass of CO2 release from the calc-silicate aureole is calculated to 0.64-9.06 Gt, where 1.30-2.67 Gt being the most realistic amount. This released CO2 has probably not caused any significant climate change on its own but may have had a small contribution to global warming together with other volcanoes that were active during the same period of time. / Magma som tränger in i karbonatrik jordskorpa, integrerar med karbonaten på flera olika sätt, t.ex. genom kontaktmetamorfos och bildande av marmor eller genom metasomatos, vilket resulterar i kalk-silikatisk skarn. Dessa processer släpper ut flyktiga ämnen, som exempelvis CO2, från karbonaten och kan därmed orsaka klimatförändring. Ett vulkaniskt komplex där intrusioner och deras omgivande metamorfa aureoler är välexponerade och därmed lämpliga för undersökning av magma-karbonat-interaktion är Carlingford Igneous Centre i nordöstra Irland. Komplexet domineras av en gabbro-lopolit och en mikrogranitisk ring-gång, som trängde in i kalksten och metasiltsten för ca 62-60 Ma. Syftet med studien är att undersöka graden av magma-karbonat-interaktion och bedöma mängden CO2 som kan ha släppts ut från aureolen i Carlingford. Detta utförs genom analysering av huvudelement och spårelement samt av kol- och svavelinnehåll i skarn- och marmorprover från en transekt genom den kalk-silikatiska metamorfa aureolen. De analytiska metoder som används är SEM-EDX, XRF, LA-ICP- MS samt kol- och svavelanalyser. Mängden CO2 beräknas genom att jämföra kol- och CO2-innehåll i skarn- och marmorprover med innehållet kol och CO2 i den ickemetamorfa kalkstenen. Resultaten visar att skarn har genomgått en stark interaktion med magman, då bergarten innehåller flera mineral av hög metamorf grad, som exempelvis wollastonit, vesuvianit och pyrop, samt har förlorat nästan allt sitt kol. Graden interaktion och mängden CO2-utsläpp är generellt mycket lägre i marmorn än i skarnen, även fast några marmorprover visar stark interaktion och en stor del avgasning. Å andra sidan är mängden marmor i aureolen signifikant högre än mängden skarn (70-90% jämfört med 10-30%). Den totala massan av CO2-utsläpp från den kalk-silikatiska delen av aureolen är beräknad till 0,64-9,06 Gt, där 1,30-2,67 Gt anses vara den mest realistiska mängden. Detta utsläpp av CO2 har troligtvis inte orsakat någon signifikant klimatpåverkan på egen hand, men kan ha haft en liten bidragande effekt till global uppvärmning tillsammans med andra vulkaner som var aktiva under samma geologiska tidsperiod.
55

[en] INFLUENCE OF THE OLYMPIC GAMES RIO 2016 IN THE ATMOSPHERIC PARTICLES: CHEMICAL, AND MORPHOLOGICAL CHARACTERIZATION AND ECOTOXICOLOGICAL EFFECTS / [pt] INFLUÊNCIA DOS JOGOS OLÍMPICOS RIO 2016 NAS PARTÍCULAS ATMOSFÉRICAS: CARACTERIZAÇÃO QUÍMICA, MORFOLÓGICA E EFEITOS ECOTOXICOLÓGICOS

MARIA FERNANDA CACERES QUIJANO 13 April 2020 (has links)
[pt] Este trabalho teve como objetivo caracterizar química e morfologicamente material particulado (PM2.5 e PM10) coletado na zona sul e oeste da cidade de Rio de Janeiro e na região metropolitana, utilizando técnicas como a Cromatografia de íons (CI), Espectrometria de Massas com Plasma Indutivamente Acoplado (ICPMS) e a Microscopia Eletrônica de Varredura acoplada ao Espectrômetro de RaiosX por Dispersão de Energia (MEV-EDX). Além disso, foram realizados ensaios toxicológicos com C. elegans para avaliar os efeitos da exposição ao material particulado (MP), nas diferentes frações de tamanho. Concentrações médias anuais de PM2.5 entre 7,40 +/- 3,96 (micrograma)m-3 e 17,4 +/- 7,38 (micrograma) m-3 foram medidas durante os anos 2015 e 2018, as quais foram inferiores ao padrão intermediário da qualidade do ar, estabelecido pelo CONAMA, registando-se as maiores médias anuais durante o 2016, ano em que foram realizados os Jogos Olímpicos. Resultados das análises químicas mostraram que o MP em todos os pontos de coleta estava constituído principalmente por espécies iônicas como Cl- , NO3 - , Na+ e SO4 2- e elementos como V, Ni, Cu, Cd, Sn e Pb, sendo determinadas apenas variações significativa (p menor que 0,05) nas concentrações de SO4 2- , NO3 - , Na+ , Cu e Sn, entre os períodos estudados. Através dos resultados das análises de MEV-EDX as partículas atmosféricas se classificaram segundo sua morfologia – Fuligem, esféricas, biológica e minerais- e segundo sua composição elementar – partículas com teor de enxofre, de cloro e de ferro -. Finalmente, efeitos tóxicos foram observados pela exposição ao PM10 e PM2.5 em organismos C. elegans, alterando parâmetros fisiológicos (e.g. crescimento e reprodução) e promovendo respostas dos mecanismos antioxidantes, como resultado do estresse oxidativo gerado por espécies presentes no MP. / [en] This work aimed to characterize chemically and morphologically particulate matter (PM2.5 and PM10) collected in the south and west zones of the city of Rio de Janeiro and in the metropolitan region, using techniques such as ion chromatography (IC), inductively coupled plasma mass spectrometry (ICP-MS) and Scanning electron microscopy- energy dispersive spectrometry (SEM-EDX). Annual mean concentrations of PM2.5 between 7,40 +/- 3,96 microgram m-3 e 17,4 +/- 7,38 microgram m-3 were measured during the years 2015 and 2018, which were lower than the intermediateair quality standard established by CONAMA, with the highest annual averages recorded during 2016, the year in which the Olympic Games were held. In addition, toxicological tests were performed with C. elegans to evaluate the effects of exposure to particulate matter (PM) in the different size fractions. Results of the chemical analysis showed that PM at all collection sites consists mainly of ionic species such Cl- , NO3 - , Na+ and SO4 2- and elements such as V, Ni, Cu, Cd, Sn and Pb, being determined only significant variations (p less than 0,05) in the concentrations of SO4 2- , NO3 - , Na+ , Cu, and Sn, between the studied periods. Based on the results of the SEM-EDX analysis, atmospheric particles were classified according to their morphology – Soot, spherical, biological and minerals- and according to their elemental composition – particles with sulfur, chlorine and iron content. Finally, toxic effects were observed by exposure C. elegans organisms to PM10 and PM2.5, altering physiological parameters (e.g growth and reproduction) and promoting antioxidant mechanisms responses, as a result of oxidative stress generated by compounds present in the PM.
56

Détermination de la pollution atmosphérique métallique : étude critique de l'utilisation des écorces d'arbres

Catinon, Mickaël 22 January 2010 (has links) (PDF)
L'atmosphère terrestre est le siège d'un transport de matière, en particulier d'éléments d'origines diverses, dont une proportion importante résulte des activités humaines. Ce phénomène induit des conséquences parfois graves, pour la santé humaine et pour la fonctionnalité des écosystèmes. Les éléments ainsi transférés sont redéposés, de manière complexe, à la surface de la terre, avec une cartographie de distribution très inégale, des possibilités d'accumulation, ou au contraire de dilution, variables, conduisant à des altérations diversifiées de la composition des eaux et des sols et de la fonctionnalité des êtres vivants. La redéposition atmosphérique est étudiée depuis une cinquantaine d'année sur les troncs des arbres, qui constituent une matrice verticale commune, très enrichie par l'apport atmosphérique, et pouvant mener soit à une analyse de composition, soit à des études de bioindication. Il en a découlé des tests de routine largement utilisés. Cependant, pour définir avec précision les apports d'origine anthropique et mieux maîtriser, en vue de les réduire, les apports anormaux ou dangereux, une étude en profondeur de cette déposition corticale devait être entreprise. C'est l'objet de ce mémoire. Au regard de la complexité du problème abordé, nous nous sommes essentiellement limité à l'étude d'une seule espèce d'arbre : Fraxinus excelsior L., très commun dans notre zone d'étude et couvrant une vaste échelle d'altitude. Notre démarche analytique a consisté à combiner une analyse élémentaire très complète et sensible, l'ICP-MS avec une observation en microscopie à balayage couplée à la détermination de l'émission de rayons X spécifique des éléments présents. Cet ensemble de deux méthodes a permis de combiner identification - dosage précis - localisation - distinction entre états particulaire et dispersé. La déposition atmosphérique a été considérée sur une échelle de temps allant de 3 mois à 40 ans, en séparant les pousses successives des arbres. Nous avons séparé le dépôt superficiel sur les surfaces végétales d'une fraction solidement intégrée dans les tissus des tiges, spécialement le suber. Ces deux entités ne correspondent pas à la même chronologie. Nous avons montré que le dépôt de surface était, de fait, un écosystème construit sur un biotope alimenté conjointement par l'atmosphère et par l'arbre lui-même et qu'il comportait une phase vivante reviviscente et pour partie photosynthétique. Ce dépôt superficiel est déplacé en grande partie par la pluie. Le suber, couche apoplastique imperméable, a une bonne capacité de rétention des éléments à long terme et constitue, comparativement aux autres tissus des tiges, une matrice très intéressante pour percevoir l'apport atmosphérique sur plusieurs décennies. Pour déterminer valablement les apports atmosphériques d'origine anthropique qui s'accumulaient dans ces deux types de matrices, nous avons conçu un système de calcul (AAEF) permettant de les séparer des apports géogéniques et biologiques. Par ailleurs, constatant que l'apport atmosphérique comportait deux types de constituants, soit dispersés, soit particulaires, nous avons conçu et mis en oeuvre un protocole de fractionnement basé 1) sur l'incinération, 2) sur les traitements successifs à l'eau et à l'acide nitrique concentré (2N) qui nous a permis d'étudier isolément une phase particulaire dans laquelle la masse des matériaux géogéniques se trouve rassemblée avec l'essentiel du plomb et du manganèse, la phase HNO3 concentrant les éléments comme le cuivre et le zinc et une phase H2O contenant l'essentiel du potassium. Les profils de distribution entre les différentes fractions semblent constituer une information intéressante sur la spéciation de plusieurs types d'éléments. L'ensemble du corpus méthodologique ainsi édifié permet d'accéder à des études assez réalistes d'historique et de distribution géographique des polluants élémentaires à des échelles de distances variées.
57

AMPLIFICATION OPTIQUE DANS DES GUIDES D'ONDE EN<br />SILICIUM POREUX DOPÉS AUX TERRES RARES

Najar, Adel, Haji, Lazhar 17 July 2007 (has links) (PDF)
Ce manuscrit, divisé en cinq chapitres, présente les différents aspects de ce travail. Le premier<br />chapitre décrit le silicium poreux et sa réalisation, les différents paramètres de formation,<br />ses propriétés structurales. Les propriétés de luminescence des ces ions (Erbium et Ytterbium)<br />sont exposées par la suite. Enfin, un état de l'art est détaillé sur les amplificateurs optiques dopés<br />Erbium déjà réalisés à partir de silicium poreux ainsi qu'à partir d'autres matériaux.<br />Le deuxième chapitre présente les conditions expérimentales d'élaboration des guides plans et<br />canaux en silicium poreux et les conditions de dopage et/ou codopage ainsi que les traitements<br />thermiques. Les méthodes de mesures de l'indice de réfraction, la photoluminescence et la photoluminescence<br />résolue en temps sont présentées. Les observations en champ proche et les mesures<br />des pertes ainsi que les mesures de gain optique sont également exposées.<br />Dans le troisième chapitre, les profils de concentration des ions terres rares pour les guides plans<br />et canaux sont présentés et discutés. Dans ce chapitre, un accent particulier estmis sur la variation<br />de l'indice de réfraction en fonction des conditions d'anodisation de dopage et des traitements<br />thermiques.<br />Le quatrième chapitre est consacré à l'étude des guides dopés et codopés par photoluminescence<br />et photoluminescence résolue en temps pour montrer l'activation des ions Erbium ainsi<br />que la détermination de la durée de vie du niveau métastable 4I13/2. Ces résultats vont nous<br />permettre d'optimiser la meilleure concentration d'Ytterbium pour le codopage ainsi que d'expliquer<br />les mécanismes d'excitation des ions Erbium. La concentration des ions Erbium actifs<br />dans les guides sera déterminée.<br />Le dernier chapitre décrit les observations en champ proche et les mesures des pertes pour les<br />guides ainsi réalisés. Le gain on/off dans les guides, définie comme étant le rapport de l'intensité<br />lumineuse du sortie avec pompage à 980 nm sur la puissance du signal de sortie sans pompage, a<br />été mesuré et exploité pour les guides codopés avec différentes concentrations d'Ytterbium. Les<br />variations du gain en fonction de la longueur d'onde sont présentées.
58

Growth and XRD Characterization of Quasicrystals in AlCuFe and Nanoflex Thin Films

Olsson, Simon January 2008 (has links)
Quasicrystals is a new kind of material that have several interesting aspects to it. The unusual atomic structure entails many anomalous and unique physical properties, for example, high hardness, and extremely low electrical and thermal conductivity. In thin films quasicrystals would enable new functional materials with a combination of attractive properties.In this work, AlCuFe and Nanoflex steel, materials that are known to form quasicrystals in bulk, have been deposited as thin films on Si and Al2O3 substrates using DC magnetron sputtering. These thin films were heat treated, and the formation and growth of different phases, among other approximant and quasicrystalline phases, were studied using mainly in-situ X-ray diffraction.During the project several problems with the formation of quasicrystals were encountered, and it is proposed how to overcome these problems, or even how to make use of them. Finally, the quasicrystalline phase was realized, although it was not completely pure. In the end some suggestions for future work is presented.
59

Chemical and Physical Properties of Atmospheric Aerosols (a) A Case Study in the Unique Properties of Agricultural Aerosols (b) The Role of Chemical Composition in Ice Nucleation during the Arctic Spring

Moon, Seong-Gi 2010 May 1900 (has links)
This study focuses on the analysis of atmospheric particles sampled from two different field campaigns: the field study at a cattle feeding facility in the summer from 2005 to 2008 and the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in 2008. A ground site field study at a representative large cattle feeding facility in the Texas Panhandle was conducted to characterize the particle size distributions, hygroscopicity, and chemical composition of agricultural aerosols. Here, a first comprehensive dataset is reported for these physical and chemical properties of agricultural aerosols appropriate for use in a site-specific emission inventory. The emission rate and transport of the aerosols are also discussed. In addition, mixing ratios of total and gaseous ammonia were measured at the same field in 2007 and 2008. Measurements such as these provide a means to determine whether the fugitive dust emitted from a typical large feedlot represents a health concern for employees of the feeding operation and the nearby community. Detailed chemical composition of aircraft-sampled particles collected during ISDAC was studied. Filter samples were collected under a variety of conditions in and out of mixed phase and ice clouds in the Arctic. Specifically, particles were sampled from a mixed-phase cloud during a period of observed high concentrations of ice nuclei (IN), a biomass plume, and under relatively clean ambient conditions. Composition of particles was studied on a particle-by-particle basis using several microspectroscopy techniques. Based on the elemental composition analysis, more magnesium was found in Arctic cloud residues relative to ambient air. Likewise, based on the carbon speciation analysis, high IN samples contained coated inorganics, carbonate, and black or brown carbon particles. In the samples collected during a flight through a biomass burning plume, water-soluble organic carbon was the dominant overall composition. Due to their hygroscopic nature, these organics may preferably act as cloud condensation nuclei (CCN) rather than IN. Other ambient samples contained relatively higher fractions of organic and inorganic mixtures and less purely water-soluble organics than found in the biomass particles. The most likely source of inorganics would be sea salt. When present, sea salt may further enhance ice nucleation.
60

Mineralogy And Production Technology Of Degirmentepe (malatya) Pottery

Er, Mehmet Bilgi 01 September 2011 (has links) (PDF)
A series of pottery samples provided from the survey investigations and excavations from Degirmentepe Mound (Malatya), belonging to Chalcolithic (Ubaid), Early Bronze and Iron Ages, were investigated by petrographic and X-ray diffraction (XRD) analyses to determine their textures, mineralogical compositions and microstructures. The sample microstructures and chemical (semiquantitative) compositions were also studied by scanning electron microscope with energy dispersive X-ray spectrometry (SEM - EDX). The chemical analyses of some samples were further investigated by inductively coupled plasma &ndash / optical emission spectrometry (ICP-OES). Almost all samples were observed to consist of rock fragments, originating from metamorphic and igneous rocks, although larger grain sizes and higher grain to matrix ratios are recorded for Chalcolithic Age samples compared to those samples belonging to Iron Age. XRD investigations on representative samples of the three periods, revealed high abundances of quartz, feldspar, and pyroxene group minerals in all samples, while the presence of hematite and mica minerals were observed both in Chalcolithic and Iron Age samples, but underlying the use of micaceous raw materials mostly in Iron Age. In the XRD traces of the investigated sherds of Chalcolithic and Iron Ages, the absence of clay fractions both in the bulk and oriented samples, supports a minimum firing temperature of around 800- 850 &deg / C, while the presence of mullite phase both in XRD and SEM &ndash / EDX results showed the possible use of high firing temperatures, in the range of 950&ndash / 1050&deg / C, starting from Chalcolithic Age. Chemical compositions of major oxides obtained ICP &ndash / OES analyses exhibit similar compositions both for Chalcolithic and Iron Age samples. Few exceptions observed may indicate possible use of different raw material and/or different manufacturing technique.

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