Thesis (M.S.)--Oregon State University, 1993. / Includes mounted photographs. Three folded plates in pocket. Typescript (photocopy). Includes bibliographical references (leaves 213-225). Also available on the World Wide Web.

Thesis (doctoral)--Universität zu Köln, 1982. / Bibliography: p. 131-144.

Thesis (M.S.)--Ohio University, November, 2003. / Title from PDF t.p. Includes bibliographical references (p. 73-77)

Geochemistry plays a vital role in our understanding mechanisms behind major geological systems such as the Earth's crust and its oceans (Albarède, F. 2003). More recently, geo-chemistry has played a vital role in the field of forensic investigation and in period dating. Forensic soil samples have been traditionally analysed via examinations of colour, texture and mineral content by physical or chemical methods. However, these methods leave any organic or water-soluble fractions unexamined. Tephrochronology (the dating of sedimentary sequences using volcanic ash layers) is an important tool for the dating and correlation of sedimentary sequences containing archives and proxies of past environmental change. Its importance in this area has increased since the increased free carbon in out atmosphere has made radio-carbon dating unreliable. Tephrochronology requires successful geo-chemical identification of the tephras, a method reliant on electron probe micro-analysis (EPMA) to analyse major element composition. However, it is often impossible to differentiate key tephra layers using EPMA alone. Raman spectroscopy is commonly used in chemistry, since vibrational information is specific to the chemical bonds and symmetry of molecules, and can provide a fingerprint by which these can be identified. Here, we demonstrate how Raman spectroscopy can be used for the successful discrimination of mineral species in tephra through the analysis of individual glass shards. We further demonstrate how, with the use of oxidative preparation methods, Raman spectroscopy can be used to successfully discriminate between soil types using mineralogy as well as the organic and water-soluble fractions of soils.

The Caucasus is a land corridor between the Black and Caspian seas, linking Africa to Northern Eurasia, and is considered a migratory route for Neanderthals and Anatomically Modern Humans (AMH). Numerous cave sites in Armenia, Azerbaijan, Georgia and southwestern Russia indicate that Neanderthals and AMH occupied the region, but poor chronological control meant that the precise timing of the occupations was unknown. This work involved identifying and geochemically characterising volcanic ash layers (tephra) in archaeological cave and open air sites spanning approximately 125 ka to 30 ka to generate a tephrostratigraphic framework. This framework was used to correlate the sites and assess the synchronicity of Neanderthal and AMH occupation across the region. Tephra investigations were also carried out on a core (M72/5-25-GC1) from the southeast Black Sea (that spans the last ~ 60 ka), with the aim of linking the archaeological sites to this palaeoenvironmental archive, to investigate the impact changes in climate had on the archaeology in the region. Eleven of the archaeological sites investigated (Gubs rock shelter and Weasel Cave in Russia; Ortvale Klde, Ortvale Cave, Sakajia and Undo Cave in Georgia; Aghitue 3, Lusakert 1, Fantan and Kagasi in Armenia; and Azokh Cave in Azerbaijan) had tephra, 30 cryptotephras and 8 visible layers, preserved. Twenty-two tephra layers were identified in the Black Sea core, with distinct periods of frequent volcanic activity separated by long periods, up to 9 ka, of seemingly volcanic quiescence in the region. The glass chemistry of the tephra found in the archaeological sites and the core, determined using a wavelength-dispersive electron microprobe, was used to characterise and correlate the units between the sedimentary sequences. Although some widespread tephra from the major Mediterranean sources (3.6 ka Minoan eruption from Santorini, Greece and the ~39 ka Campanian Ignimbrite super eruption from Campi Flegrei, Italy) were identified in the Black Sea core, none of the archaeological sites contained Mediterranean tephra. Most of the tephra layers in the archaeological sites investigated and the Black Sea core are from sources in the Caucasus and Turkey. The limited information on the volcanic history and compositional data of these sources in the region does not allow most of the units to be correlated to particular eruptions or volcanoes. However, some of the cryptotephra units have been correlated to eruptions from Nemrut, Acigöl and Erciyes Dagi volcanoes in Turkey. Unfortunately, there are no tephra layers that are common to the Black Sea core and any of the archaeological sites, prohibiting direct correlation of the sites to this detailed palaeoenvironmental record. However, the ~30 ka Nemrut Formation (NF) eruption from Nemrut volcano, Turkey, is found in the Lake Van palaeoenvironmental record and in two of the archaeological sites. This allows the archaeological sites to be correlated to each other and palaeoclimate information can also be imported into these sites. More detailed characterisation of the proximal deposits may allow more units to be correlated to eruptions and will enable these distal records to be used to further constrain the tempo of explosive volcanic activity in the region. A few compositionally distinct tephra layers were found and a suite of new radiocarbon dates were obtained at various sites, allowing archaeological occupations to be dated and the synchronicity between sites to be assessed. A distinct rhyolitic tephra correlates a layer with an Upper Palaeolithic stone technology, associated with AMH, in Azokh Cave (Azerbaijan) to a layer in Sakajia cave (Georgia) that contains Neanderthal remains. This is clear evidence that AMH and Neanderthals were in the region (within 600 km) at the same time. Other sites have also been correlated with tephra. A dacitic tephra correlates a unit with an Upper Palaeolithic lithic and bone tool techno-complex in Ortvale Klde (Georgia) to a unit with a Middle Palaeolithic lithic assemblage in Lusakert 1 (Armenia). The Middle Paleolithic tool assemblage in Lusakert 1 is clearly different from the Upper Paleolithic assemblage that is clearly associated with AMH in Ortvale Klde, but it is not clear whether the other assemblage is associated with Neanderthals, archaic modern humans or AMH. This correlation between different lithic assemblages clearly indicates that there were different groups, with different technologies, occupying the region at the same time. The NF tephra is also found shallower in the sequences at both Lusakert 1 and Ortvale Klde. This time marker shows that the Middle Paleolithic assemblage is still being used in Lusakert 1 at ~30 ka, indicating that a less diverse stone techno-complex was used for a prolonged period of time in central Armenia. There does not appear to be any direct relationship between occupation in the region and the climate at the time, implying that this had little effect on the archaeological story in the region. A new radiocarbon based age model that combines new dates with published data for the sites within the Caucasus shows temporal overlap between AMH and Neanderthals in the region. This confirms the tephra correlations and clearly indicates both species co-existed in the Caucasus. The new radiocarbon data also suggest that AMH arrived in the region earlier than previously thought, at ~50-44 ka cal BP. The arrival of AMH in the Caucasus is now temporally similar to other early AMH sites in northern Eurasia.

No description available.

State of the art thermal barrier coatings (TBCs) for gas turbine applications comprise (7 wt.%) yttria partially stabilized zirconia (7YSZ). 7YSZ offers a range of attractive functional properties – low thermal conductivity, high thermal expansion coefficient and high in-plane strain tolerance. However, as turbine entry temperatures are raised, the performance of 7YSZ coatings will be increasingly affected by sintering and environmental contamination, by calcia-magnesia-alumina-silica (CMAS) deposits. The effect of sintering-induced stiffening on the driving force for spallation of plasma-sprayed (PS) TBCs was investigated. Spallation lifetimes of TBC specimens sprayed onto alumina substrates were measured. A simple fracture mechanics approach was employed in order to deduce a value for the strain energy release rate. The critical strain energy release rate was found to be constant, and if this value had been known beforehand, then the rationale presented here could be used for prediction of coating lifetime. The effect of vermiculite (VM) and volcanic ash (VA) contamination on the sintering-induced spallation lifetime of PS TBCs was also investigated. The presence of both VM and VA was found to accelerate the rise in their Young’s modulus with sintering. Spallation results show that coating lifetime may be significantly reduced, even at relative low addition levels, due to the loss of strain tolerance caused by the penetration of glassy deposits. This result gives a clear insight into the role CMAS plays in destabilizing TBCs. Finally, the adhesion characteristics of ingested volcanic ash were studied using a small jet engine. The effects of engine speed and particle size were investigated. Deposition on turbine surfaces was assessed using a borescope. Deposition mainly occurred on the nozzle guide vane and blade platform. A numerical model was used to predict particle acceleration and heating in flight. It was observed that larger particles are more likely to adhere because they have greater inertia, and thus are more likely to impact surfaces. The temperature of the larger particles at the end of its flight was predicted to be below its softening point. However, since the component surface temperatures are expected to be hotter, adhesion of such particles is probable, by softening/melting straight after impact.

More than two million people in the Chaco-Pampean plain in central Argentina are affected by high As levels in groundwater. The concentrations of As are far exceeding the WHO standard limit for safe drinking water of 0.1 μg/L and the provisional Argentinean limit of 0.5 μg/L. The NE of La Pampa province is one of the areas affected with geogenic As in shallow aquifers within the Chaco-Pampean plain. These aquifers are in closed basins and they are only available water resource of the region for drinking and agriculture purposes. The Pampean aquifer is composed of a multi-layered system of Quaternary loess deposits covered by aeolian sands and also containing layers of rhyolitic volcanic ash, which is considered the primary source of As. Volcanic ash layers can be visible in the shallow sediments or intermixed in the loess. During the weathering of volcanic ash sediments As is dissolved to the aqueous phase and can be quickly adsorbed or co-precipitated on secondary Fe, Al and Mn oxy-hydroxides under favourable conditions. Also, previous more arid climatic conditions have led to the formation of carbonate "calcrete" layers in the top sequences of the loess and this has affected the geochemistry of the aquifer. Two sites were investigated in the NE of La Pampa province in order to assess (i) the quality of groundwater for drinking water use, (ii) the distribution of As and other trace elements in shallow aquifers and (iii) to understand better the factors controlling its mobility in groundwater. The results showed that groundwater was circum-neutral to alkaline and under moderate oxidizing conditions. The predominant groundwater composition was of Na-HCO3 for fresh water and Na-Cl-SO42- for brackish water types. High salinity levels are evidenced by the high Electrical Conductivity and might be explained by to the high evaporation rates. Groundwater sampled in both areas was enriched with As, F and other trace elements at different ranges of concentration. From the total As concentrations, arsenate As(V) predominated over arsenite As(III) species. Shallow groundwater is also enriched with fluoride exceeding the WHO standard limit of 1.5 mg/L and placed in the same As hotspots. One possible factor controlling the mobility of As is the high pH of groundwater, which is controlled by the carbonates equilibrium. Under this high pH conditions As is less strongly bind to Fe, Al and Mn oxy-hydroxides and can be easily mobilized to groundwater when other competing ions are getting adsorbed on the surface sites of binding minerals.

This study outlines the ash (tuff) bed stratigraphy (tephrostratigraphy) in the middle Eocene Chumstick Formation of central Washington. The tuff beds provide local marker beds enabling interpretation of the stratigraphy and structure of the formation. The chemical signature of these units provides the basis on which the units can be traced over broad areas in the basin of deposition. Correlations of tuff beds were obtained over distances of 41 km.

El objetivo principal de este trabajo consiste en una propuesta de negocio a través de la cual se comercializa la bentonita con el fin de que las personas que la utilicen como una mascarilla, que puedan cuidar su piel y disfruten de los beneficios que esta les brinda. Algunos de estos son la eliminación de impurezas y residuos, reducción del acné. Asimismo, este tipo de ceniza volcánica suaviza la piel, puede ser utilizada por personas que cuentan con piel sensible y rosácea. Las campañas publicitarias y las nuevas exigencias sociales han determinado ciertos estereotipos y características que se deben cumplir para que una persona se considere estéticamente atractiva. Afectando de manera directa el autoestima y estado de ánimo de los individuos que no cumplen con ellas. A partir de esta situación, Bitamask brinda a las personas la oportunidad de cuidar y mejorar la apariencia de su piel, con el objetivo de solucionar o reducir imperfecciones que puedan tener con el fin de incrementar su autoestima y mejorar su estado de ánimo. Por otro lado, este trabajo fue elaborado de acuerdo a las normas vigentes dictadas por la Universidad Peruana de Ciencias Aplicadas y ha sido realizado por alumnos de la Facultad de Negocios. A continuación, se presentará la investigación y propuesta realizada. / The main objective of this paperwork is a business proposal through which bentonite is marketed so that people who use it as a mask, can take care of their skin and enjoy the benefits it offers. Some of these are the elimination of impurities and dirt, and reduction of acne. Also this type of volcanic ash softens the skin and can be used by people who have sensitive skin and rosacea. Advertising campaigns and new social demands have determined certain stereotypes and characteristics that a person must have in order to be considered aesthetically attractive. Directly affecting the self-esteem and state of mind of people who do not comply with them. From this situation, Bitamask offers people the opportunity to care for and improve the appearance of their skin, with the aim of solving or reducing imperfections that may have in order to increase their self-esteem and improve their mood. On the other hand, this paperwork was prepared in accordance with the regulations dictated by the Peruvian University of Applied Sciences and has been carried out by students of the Faculty of Business. Now, the research and proposal made will be presented. / Trabajo de investigación