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Dissertations / Theses on the topic 'Iron deposition'

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Published: 4 June 2021
Last updated: 2 February 2022

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1

Blickensderfer, Jacob K. "Electroless Deposition of Amorphous Iron-Alloy Coatings." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1510185065054813.

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2

Low, Y. H. "Chemical vapour deposition of iron and cobalt layers." Thesis, Queen's University Belfast, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437845.

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3

Lehmberg, Claudia Erdmuthe. "Structure of nickel-iron and nickel-zinc electrodeposits." Thesis, Sheffield Hallam University, 1998. http://shura.shu.ac.uk/3118/.

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Electrodeposited nickel-iron and nickel-zinc alloys have been studied using `direct' methods e. g. XRD, microscopy, EDX and GDOES on coatings having different thicknesses and deposited on different substrates. The work has confirmed and extended the ideas of Finch et al. (2, 51), Piontelli et al. (3) and Pangarov (49.120, 121) applicable to alloy deposition. It has shown that a better understanding, particularly of the initial deposition stages, can be obtained by considering crystallographic, energy and electrochemical aspects in combination rather than individually. Initially alloy is deposited on a `foreign' substrate but subsequently the growing alloy itself serves as the `substrate'. Similarly `old' crystallites have to compete for growth with `newly' nucleated ones as the deposit develops. The three stages of growth observed in nickel-iron and nickel-zinc are discussed. Crystallographic strain, resulting from mismatch between substrate and deposit structures and the presence of impurities, along with the energies required to produce different structures are considered to play a major role in determining structure during alloy deposition. Competition for discharge between hydrogen and metallic ions at the changing deposit surface, including changes in its electrochemical nature are considered. In addition possible effects resulting from adsorbed species, including co-discharged hydrogen as well as other species such as hydroxyl ions or precipitated hydroxides are discussed. Whereas during initial nucleation the original substrate is the dominating influence, in the later stages the electrolytic parameters determine the structure of the deposit. If the structure of the outer deposit differs markedly from that of the deposit during the initial stages, then a transitional growth stage may be involved. The structures of deposits studied in the present work tended to be fine grained in the initial stages but developed coarser columnar structures due to selected grain growth with favoured grains becoming broader during the intermediate and final stages of growth.
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4

Kulkarni, Dhananjay Vijay. "Electrochemical deposition of green rust on zero-valent iron." Thesis, Texas A&M University, 2005. http://hdl.handle.net/1969.1/3753.

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Perchloroethylene (PCE) is a toxic contaminant that has been introduced into the environment over many years through industrial and agricultural wastes. Research has been done in the past to investigate PCE degradation by zero-valent iron (ZVI), green rust (GR) and a mixture of both. The combination of ZVI and green rust has been reported to be more effective for degrading PCE than either of them alone. Forming green rust electrochemically has the potential for depositing GR more effectively on the surface of ZVI where it will be able to more easily transfer electrons from ZVI to contaminants such as PCE. Therefore, the goal of this research was to determine the feasibility of electrochemically depositing green rust on zero-valent iron and to characterize it in terms of its composition, crystal properties and amount produced. XRD analysis was conducted to determine composition and crystal properties and a procedure was developed to measure the amount produced. Equipment was constructed to deposit green rust electrochemically onto ZVI. A chain of experiments with varying voltage, pH, time and amounts of ZVI were conducted to determine feasible experimental conditions for GR formation. Then, a method was developed to accurately measure the amount of surface oxides of iron deposited on the zero-valent iron substrate. This method was tested and found useful for measuring iron in: i) standard solutions of soluble iron with different concentrations of reagents; ii) suspensions with solid iron hydroxides by themselves; and iii) suspensions with solid iron hydroxides and ZVI. Electrochemical experiments were conducted and the amounts of iron hydroxides deposited on the ZVI surface were measured. XRD analysis of the deposits on the surface was conducted and the patterns of XRD-peaks were compared to that of type 2 – sulfate green rust.
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5

Kawamori, Makoto. "Designing of Iron Group Metallic Nanomaterials via Electroless Deposition." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174932.

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6

Tian, Zhenglong. "Coupling between atmospheric deposition and oceanic flux of Fe and Al in the Sargasso Sea." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 135 p, 2007. http://proquest.umi.com/pqdweb?did=1253511061&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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7

Song, Yi Ph D. Massachusetts Institute of Technology. "Iron (III) Chloride doping of large-area chemical vapor deposition graphene." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82384.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.
Title as it appears in MIT Commencement Exercises program, June 2013: Iron Chloride doping of CVD graphene for transparent electrodes. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 39-40).
Chemical doping is an effective method of reducing the sheet resistance of graphene. This thesis aims to develop an effective method of doping large area Chemical Vapor Deposition (CVD) graphene using Iron (III) Chloride (FeCl 3). It is shown that evaporating FeCl3 can increase the carrier concentration of monolayer graphene to greater than 7x1 0 3CM2 and achieve resistances as low 72[Omega]/sq. We also evaluate other important properties of the doped graphene such as surface cleanliness, air stability, and solvent stability. Furthermore, we compare FeCl3 to three other common dopants: Gold (III) Chloride (AuCl3), Nitric Acid (I-N0 3), and TFSA ((CF 3SO2)2NH). We show that compared to these dopants, FeCl3 can not only achieve better sheet resistance but also has other key advantages including better solvent stability and better heat stability.
by Yi Song.
S.M.
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8

McKinty, Colin N. "Characterisation of beta-FeSi2 fabricated by ion beam assisted deposition." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/842704/.

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beta-FeSi2 has been shown to have a minimum direct band gap of 0.87 eV, which leads to the opportunity of Si based opto-electronics. One of the many applications that beta-FeSi2 has been linked with is solar cells. Its proposed suitability for solar cell applications originates from a large absorption coefficient above the fundamental edge (105 cm-1), predicted solar cell efficiencies as high as 23% and photoelectric properties with a quantum efficiency of 32%. Ion beam assisted deposition represent a technique that is suitable for producing low cost material over large areas, thus making it suitable for solar cell fabrication. The work reported here represents an in-depth optical characterisation of the effects of fabrication and post-fabrication processing on ion beam assisted deposited FeSi layers on Si substrates. Two different sets of substrates have been investigated; the first were deposited with layers of Fe and Si in the ratios between (40%:60%) and (29%:71%), and the second were deposited in stoichiometric ratios (1:2). A range of post-fabrication processes have been investigated, these have included studying the effects of annealing time (10 minutes to 18 hours) and temperature (100°C to 900°C) on the band gap and defects underneath the fundamental absorption edge. A study of the effect of annealing regime on the measurement temperature dependency of the band gap was also completed. The results have shown that annealing temperature has a stronger effect on the band gap rather than annealing time, while both affect the absorption underneath the fundamental edge. Optical evidence for the formation of beta-FeSi2 was found for annealing temperatures as low as 425°C. Increasing the annealing temperature/time also results in structural changes in the material, which are dependent on the as-deposited composition of the FeSi layer. beta-FeSi2/Si(n-type) solar cell devices have been fabricating, showing rectifying I-V characteristics, and a photo-voltage spectral response that indicated two distinct regions; 0.72 eV to 1.1 eV and 1.1 eV and above.
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9

Williamson, R. D. "The deposition of iron oxide particles on surfaces from turbbulent aqueous suspension." Thesis, University of Birmingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525011.

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10

Willaimson, R. D. "The deposition of iron oxide particles on surfaces from turbulent aqueous suspension." Thesis, University of Birmingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525001.

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Iron oxide particle deposition is a common form of fouling of heat exchange surfaces and is important in radioactive corrosion product transport. The present work relates to deposition in fully turbulent isothermal conditions from non-boiling aqueous suspensions onto metal tubes using particles of Haematite (Fe303) for which transport through the boundary layer was expected to be predominantly diffusional. A radioactive technique has been used to measure deposition rate onto clean stainless steel and aluminium surfaces, the growth of deposit with time and the rate of removal of particles as clean water is passed over the deposit. In view of the known effect of particle size on mass transfer, attempts were made to use particles of uniform size. The performance of a small diameter hydrocyclone was investigated as a means of obtaining a monodisperse suspension from commercially available powders but these were eventually discarded in favour of particles manufactured using a controlled precipitation process. Water chemistry has been demonstrated to have a profound effect on particle deposition from turbulent flow which is similar to that found by workers experimenting in systems with laminar flow. The mass transfer coefficients measured under favourable conditions of water chemistry agreed extremely well with predicted values. The asymptotic level of deposit was found to decrease as fluid velocity increased approximately to the power 1.3 which cannot easily be explained using currently available mechanistic descriptions. The rate of decrease in deposit thickness as clean 'water is passed over it was finite. However this was around an order of magnitude lower than that required to indicate that continuous removal of particles by turbulent bursting in the laminar sublayer or other fluctuations in the forces of the particles is the major factor responsible for asymptote formation.
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11

Kahl, Sören. "Bismuth iron garnet films for magneto-optical photonic crystals." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3711.

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The thesis explores preparation and properties of bismuthiron garnet (BIG) films and the incorporation of BIG films intoone-dimensional magneto-optical photonic crystals (MOPCs).

Films were prepared by pulsed laser deposition. Weinvestigated or measured crystallinity, morphology,film-substrate interface, cracks, roughness, composition,magnetic coercivity, refractive index and extinctioncoefficient, and magneto-optical Faraday rotation (FR) andellipticity. The investigations were partly performed onselected samples, and partly on two series of films ondifferent substrates and of different thicknesses. BIG filmswere successfully tested for the application of magneto-opticalvisualization. The effect of annealing in oxygen atmosphere wasalso investigated - very careful annealing can increase FR byup to 20%. A smaller number of the above mentionedinvestigations were carried out on yttrium iron garnet (YIG)films as well.

Periodical BIG-YIG multilayers with up to 25 single layerswere designed and prepared with the purpose to enhance FR at aselected wavelength. A central BIG layer was introduced asdefect layer into the MOPC structure and generated resonancesin optical transmittance and FR at a chosen design wavelength.In a 17- layer structure, at the wavelength of 748 nm, FR wasincreased from -2.6 deg/µm to -6.3 deg/µmat a smallreduction in transmittance from 69% to 58% as compared to asingle-layer BIG film of equivalent thickness. In contrast tothick BIG films, the MOPCs did not crack. We were first toreport preparation of all-garnet MOPCs and second toexperimentally demonstrate the MOPC principle inmagneto-optical garnets.

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12

Francis, John Anthony. "Principles for open-arc weld deposition of high-chromium white iron surface layers /." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phf81845.pdf.

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13

Ibrahim, Noor Baa'yah. "Properties of yttrium iron garnet thin films grown by pulsed laser ablation deposition." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343112.

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14

Davis, Stephen J. "The deposition and organisation of inorganic and organic adhesion promoters on iron surfaces." Thesis, University of Surrey, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308551.

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15

Macintosh, Katrina A. "Distribution and dynamics of iron deposition in streams and its effects on aquatic ecology." Thesis, University of Ulster, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553858.

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Availability of iron in an aquatic system is governed by the concentrations present within the catchment and prevailing environmental conditions. Iron is characterised by low solubility at circumneutral pH. Conversion of ferric iron, into soluble ferrous iron, requires a reduction in pH and redox potential. Research to date has tended to focus upon acid mine drainage, where anthropogenic activity initiates extreme acidity and the liberation of mobile iron. In instances of naturally occurring deposition, the acidity is derived from ecological processes, such as organic decay, respiration and natural acids. Once in the soluble form, iron is vulnerable to rainfall induced transport into receiving waterbodies. Precipitation of iron, from the water onto the streambed, takes place when pH increases downstream and conditions become increasingly oxidised. Interaction between iron-water and deposit concentrations was explored across the Antrim Plateau and Sperrin Mountains, in Northern Ireland. Basalt and brown earths dominate the Antrim Plateau, whereas the Sperrin Mountain soils are composed of peat underlain by schist. Significant relationships existed between water and deposit concentrations across both localities. Concentrations of deposit iron were consistently less in the Antrim Plateau, due to lower levels of iron in the water, as a consequence of variance in soil and rock type. In the Sperrin Mountains, eight streams were sampled monthly for one year, over a range of high to low iron sites. Seasonal variation in rainfall influenced iron concentrations in the water. The solubility of iron within streams in the Sperrin Mountains is predominantly controlled by pH. Dissolved oxygen was less influential owing to the hydrodynamics of upland stream networks, which are generally fast flowing and well oxygenated. The occurrence of iron deposition is therefore dependent upon the concentration of iron in the water and the pH of the waterbody. Composition of deposit material present on stone and tile substrates was analysed. Metal concentrations increased with increasing deposit density. A strong association also existed between deposit iron and organic matter concentration. Chlorophyll a concentrations increased with increasing deposit density, up to a critical point, after which they began to decline as deposit density continued to rise. Autotrophic index values behaved negatively with chlorophyll a concentration and positively with deposit organic matter and iron. The density of deposit material present within streams has a strong influence upon both the abundance of algae and invertebrate community structure. Deposit iron concentrations in excess of 1.0 mg cm-2 had a deleterious effect upon chlorophyll a concentration. Invertebrate numbers were also detrimentally affected by elevated concentrations of iron. Species composition was principally controlled by the density of deposit iron, which influenced algal abundance and controlled community structure in relation to feeding habit. The accumulation of deposit iron alters stream ecosystem functioning and facilitates the transition from autotrophy to heterotrophy. Key attributes of stream ecology are, therefore, altered by iron deposition as a result of food web simplification.
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16

Stadler, Daniel [Verfasser]. "Magnetic Field-assisted Chemical Vapor Deposition of Iron, Vanadium and Titanium Oxides / Daniel Stadler." München : Verlag Dr. Hut, 2021. http://d-nb.info/1233525573/34.

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17

Akhtar, Masood. "Synthesis of iron chalcogenide nanocrystals and deposition of thin films from single source precursors." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/synthesis-of-iron-chalcogenide-nanocrystals-and-deposition-of-thin-films-from-single-source-precursors(1f2ca1fd-da28-4da8-95a4-7bba81c8b1c6).html.

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Recently there is growing interest for the production of cheap and nontoxic colloidal nanomaterials or thin films for photovoltaic applications. Iron chalcogenides are cheapest materials available for solar cell applications. The work presented here involve the synthesis of iron chalcogenide nanocrystals by colloidal methods and the deposition of thin films by aerosol assisted chemical vapour deposition (AACVD) method from single source precursors. In addition, a comprehensive literature review of iron chlacogenide nanocrystals and thin films is presented. Several new iron complexes belonging to thiocarbamato, xanthato, selenoureato and imidodiphosphinato, have been synthesised. Tris(dialkyldithiocarbamato)-iron(III) complexes of general formula [Fe(S2CNRR’)3] where R = Et, R’ = iPr; R, R’ = Hex; R = Me, R’ = Et and R, R’ = Et and tris(O-alkylxanthato)iron(III) complexes of general formula [Fe(S2COR)3] where R = Me, Et, ipr and iBu have been synthesised. The X-ray single crystal structure of [Fe(S2CNEtiPr)3], Fe(S2CNEtMe)3 and [iPrOC(S)S-S(S)COiPr] were determined. Iron complexes were used as a single source precursors for the deposition of iron sulfide nanocrystals by thermolysis in oleylamine, hexadecylamine and octadecene and thin films on silicon substrate at different temperatures. The complexes show typical paramagnetic behaviours whereas the iron sulfide nanocrystals produced show ferromagnetic behaviour. The greigite and pyrrhotite phases with hexagonal and cubic morphology were obtained by thermolysis. Pyrite and pyrrhotite phases were dominant in thin films. The complex tris(N,N-diethyl-N’-naphthoylselenoureato)iron(III) and its X-ray single crystal structure is also reported. Long rod like nanocrystals of orthorhombic ferroselite (FeSe2) obtained by thermolysis in oleylamine, dodecanthiol and in the mixture of oleylamine and dodecanthiol at 190, 240, and 290 °C. Paramagnetic behaviour was found under magnetic measurement of iron selenide nanocrystals. A very thin film of iron selenide (FeSe) phase was deposited on silicon substrate at 625 °C by AACVD method. The complexes [Fe{(SePiPr2)2N}2] and [Fe{(SePPh2)2N}2] were synthesised. The X-ray single crystal structure of [Fe{(SePPh2)2N}2] and [(SePPh2)2N)-O-(SePPh2)2N)] were also reported. A mixture of orthorhombic ferroselite (FeSe2) with rod and plate-like crystallites was obtained from the thermolysis of these complexes in oleylamine and hexadecylamine at 190, 240 and 290 °C temperatures. Also the mixed phases of iron selenide (Fe7Se8 and FeSe2) thin films having rod and sheet-like morphology were deposited at different deposition temperature (500, 550 and 600 °C) onto silicon substrates from these complexes.
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18

Trapp, John Michael. "Chemistry of Iron and Other Trace Elements in Trade Wind Aerosols and Precipitation." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/323.

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The atmospheric transport of various substances from the continents to the oceans plays an important role in biogeochemical processes. Trace metals, iron in particular is of great interest as its availability regulates the growth of phytoplankton over large areas of the ocean. This dissertation focuses on examining and characterizing the factors that affect the solubility of trace metals in Miami and Barbados aerosols and precipitation, in particular species that could play a role in surface seawater biogeochemistry (Fe and trace metals such as Al, V, Cr, Mn, Cu, Co, Ni, Zn, As, Tl, Ba, Cd, Pb, Th, Ti, Zr, and REE's). To enable this study existing methods of colorimetric spectroscopic and inductively coupled plasma mass spectrometry analysis were improved and modified. This dissertation examines several issues related to source inputs: 1.) Are single spot sources within the North African dust source distinguishable after long transport by their bulk metal composition and thus important in the characteristics of individual mineral dust samples? 2.) What is the temporal variability and controlling factors in trace metal solubility in trade wind aerosols collected over Barbados? 3.) Which factors control the observed trend of speciation and increasing iron solubility in decreasing aerosol loading? Additionally a kinetic model of species specific iron (II) to iron(III) oxidation kinetics in NaCl Brines was conducted at nano-molar levels. This study greatly expands the ability to predict rates of iron oxidation at concentrations closer to those observed in natural systems.
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19

Shankle, Angela Janine Arnett. "Influence of water on the photocatalytic properties of synthetic nanocrystalline iron oxide films." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1798967601&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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20

Gapara, Cornwell Sine. "A review of the deposition of iron-formation and genesis of the related iron ore deposits as a guide to exploration for Precambrian iron ore deposits in southern Africa." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005610.

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Iron-formations are ferruginous sedimentary rocks which have their source from fumarolic activity associated with submarine volcanism, with deposition of iron as oxides, hydroxides, and hydrous oxide-silicate minerals in shallow and/or deep marine sedimentary systems. The Precambrian ironformations of southern Africa have a wide age range, but are more prominently developed before 1.SGa. These iron formations occur in greenstone belts of the Kaapvaal and Zimbabwean cratons, in the Limpopo mobile belt, in cratonic basins and in the Damara mobile belt. The Archaean-Proterozoic sedimentary basins and greenstone belts host iron ore deposits in iron-formation. Iron formations have a lengthy geological history. Most were subjected to intense, and on occasions repeated, tectonic and metamorphic episodes which also included metasomatic processes at times to produce supergene/hypogene high grade iron ores. Iron-formations may be enriched by diagenetic, and metamorphic processes to produce concentrating-grade ironformations. Uplift, weathering and denudation, have influenced the mineral association and composition of the ores, within which magnetite, haematite and goethite constitute the major ore minerals. The iron resources of the southern Africa region include the Sishen deposits, hosting to about 1200 Mt of high grade direct shipping ore, at >63% Fe. Deposits of Zimbabwe have more than 33 000 Mt of beneficiable iron-formation. The evaluation of an iron ore prospect involves many factors which must be individually assessed in order to arrive at an estimate of the probable profitability of the deposit. Many of these are geological and are inherent in the deposit itself. Other factors are inherent aspects of the environment in which the ore is formed. Although the geological character of the ore does not change, technological advances in the processing techniques may have a great effect on the cost of putting the ore into marketable form. Geochemical, geophysical and remote sensing methods would be used for regional exploration. Chip sampling and drilling are useful for detailed exploration. Purely geological exploration techniques are applicable on a prospect scale in the exploration of iron ore deposits. Regional exploration targeting should choose late Archaean greenstone belts containing oxide facies iron-formation or Early Proterozoic basins located at craton margins as they are both known to host high-grade haematite orebodies formed by supergene/hypogene enrichment. Most types of iron ore deposits in southern Africa are described and classified. An attempt is made to emphasize the major controls on mineralisation, in the hope that these may be applicable to exploration both in the southern African region and within analogous settings around the world.
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21

Sheehan, Stafford Wheeler. "Atomic Layer Deposition Synthesis and Photoelectrochemical Charge Behavior in Tungsten, Iron, and Titanium Oxide Heterostructures." Thesis, Boston College, 2011. http://hdl.handle.net/2345/2203.

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Thesis advisor: Dunwei Wang
This thesis explores new approaches to synthesizing and understanding photoanodes for water splitting. By tuning materials' mophology on the nanoscale, their ability to absorb light energy and efficiently convert it in to chemical energy is improved. This is evident by an increase in photocatalytic efficiency and can be demonstrated with visible light sensitive catalysts. Production of these materials involved the development of alternative synthesis routes for traditional water splitting catalysts. Our hypothesis is further supported by probing charge dynamics using microwave reflectivity measurements, which show that the lifetime of charges in these new nanostructures is optimized
Thesis (BS) — Boston College, 2011
Submitted to: Boston College. College of Arts and Sciences
Discipline: Chemistry Honors Program
Discipline: Chemistry
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22

Curteis, Mark Edward. "The Iron Age coinages of the south midlands, with particular reference to distribution and deposition." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/1231/.

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The last twenty years has seen a great increase in the number of recorded provenance Iron Age coins. The same period has also seen advances in archaeological ideology particularly with regards to depositional processes and the inter-relationship between material assemblages and their contexts. This study re-examines existing potheseasn d developsn ew hypotheseisn light of the new data to address fundamental questions about who used iron Age coins and why A detailed catalogue ofall coins found in the south midlands is included After a review of the history of research into Iron Age coins and an overview of the development of British Iron Age coinage, particularly north of the Thames, there is a detailed look at the distributions of each major coin type found in the south midlands. The distributions have produced many interesting conclusions on the primary circulation areas of coins and hence areas of political unity, the position of possible boundaries between such areas, possible issuing authority, relative chronology and the significance of metallic content. A distribution/expansion theory has been proposed to introduce a non-stylistic approach for identifying the relative chronologies of the issues of Tasciovanus. An important part of the thesis is an archaeological study of the types of site coins are recovered from, the type, location and date of features containing coins within such sites, and detailed contextual analyses concerning material associations and position within features. From the contextual analysis it was concluded that most Iron Age coins were deposited in a deliberately structured way in specified locations, often in special votive deposits, were closely associated with other aspects religious ritual activity, and that this role continued in to the Roman period.
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Adams, Sophia Anne. "The first brooches in Britain : from manufacture to deposition in the Early and Middle Iron Age." Thesis, University of Leicester, 2014. http://hdl.handle.net/2381/28593.

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This thesis explores the evidence for the earliest brooches in Britain. The first brooches were used and made in Britain in the Early Iron Age from c.450 BC. During this period, and into the Middle Iron Age, methods were devised for constructing brooches with mock springs and hinges. In tandem with these changes a greater variety of types came into use. Some are relatively widespread across Wales, England and into Scotland. Others are concentrated in central or western and eastern regions of England. Brooches were manufactured from both bronze and iron. Bronze brooches dominate in the earlier period but iron brooches are as common as bronze in the Middle Iron Age. Some bronze brooches are constructed with small elements of iron and vice versa. Other materials are also employed as decoration on the body of the brooch including coral and glass. A revised chronology and typology are proposed, drawing on both intrinsic attributes and external archaeological evidence. The evidence from burials shows brooches were used to clasp fabric. The fabric was probably a woollen cloak wrapped around the body as a shroud. The brooch was positioned so it was visible during the funerary process. Some brooches fastened bags and other small brooches were better suited as ornaments or badges. These have distinctive designs that would have made them recognisable, perhaps as objects belonging to a particular person and/or associating that person with a specific group. Brooches are also found at settlements, at hillforts and in rivers, as well as at sites with or deposits of a ritualised character. Aside from cemeteries these latter sites contain the highest numbers of brooches. The deposition of personal objects at these types of site may have asserted the individual’s connection to the community in a manner comparable to the burial of a person in a cemetery.
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Suhor, Muhammad Firdaus. "Effect of Iron Carbonate Deposition on Mild Steel Corrosion in High Partial Pressure Carbon Dioxide Systems." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1532376719359574.

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25

Watts, Susan Rosina. "The structured deposition of querns : the contexts of use and deposition of querns in the south-west of England from the Neolithic to the Iron Age." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4016.

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It is now widely assumed that many artefacts found in the prehistoric archaeological record were not casually discarded as unwanted material but were deposited in features and contexts with structure and meaning. This appears to include saddle and rotary querns for they are often found whole and apparently still usable or, conversely, deliberately broken. Analysis of the structured deposition of querns in the south-west of England shows that they were deposited in features on both domestic and non-domestic sites. Furthermore, the location and state of the querns, together with the artefacts found in association with them, indicates that they were deposited with different levels and layers of meaning, even within the same type of feature. The deposition of querns appears to have pervaded all aspects of prehistoric life and death suggesting that they played a role above, but nevertheless related to, their prime task of milling. An exploration of the object biography of querns demonstrates the importance of what are often considered to be mundane tools to subsistence communities. Each quern has its own unique life history, its meaning and value determined by the reasons that gave cause for its manufacture, the material from which it was made, the use(s) to which it was put and who used it. However, all querns share points of commonality, related to their function as milling tools, their role as transformers of raw material(s) into usable products (s), their association with women and the production of food, and the movement of the upper stone. Through these, symbolical links can be made between querns and agricultural, human and building life cycles, gender relations and the turning of the heavens. The reason for a quern’s deposition in the archaeological record may have drawn upon one or more unique or common values.
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Noyan, Selin. "Production Of Boron Nitride Nanotubes From The Reaction Of Nh3 With Boron And Iron Powder Mixture." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615045/index.pdf.

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Boron nitride nanotubes (BNNTs), which are structurally similar to carbon nanotubes (CNTs), were synthesized in 1995 for the first time. They are made up by folding atom sheets which consist of boron and nitrogen atoms into cylindrical form. After their discovery, BNNTs have been attracting great attention due to their extraordinary mechanical, thermal, electrical, and optical properties. In this study, BNNTs were synthesized from the reaction of ammonia gas with the boron and iron powder mixture in a tubular reactor which was connected to a mass spectrometer for on-line chemical analysis of the reactor effluent stream. The synthesized materials were purified with acid treatment. Chemical analysis results showed that nitrogen and hydrogen gases were present in addition to ammonia gas. XRD results revealed that the solid phases in the synthesized material were hexagonal boron nitride, rhombohedral boron nitride, iron, and boron-iron compounds (FeB49 and Fe3B). Reactions taking place in BNNT synthesis were proposed as the decomposition of ammonia gas which was the only gas phase reaction, the formation of boron-iron compounds from the reaction of boron with iron, and boron nitride formation from the reaction of nitrogen with boron-iron compounds. Agglomerated, hollow, multi-walled nanotubes were synthesized with an outer diameter range of 10-550 nm. Both open and close-ended nanotubes were observed. The interlayer distance between BN sheets was measured about 0.33 nm and this distance indicated the d002 plane of hexagonal boron nitride. BNNTs exhibited Type II isotherms with a Type B hysteresis. A decrease in the surface area of the synthesized BNNTs was observed with an increase in temperature. The highest surface area was 147.6 m2/g. Average pore diameter of BNNTs synthesized at different temperatures was around 38 Å
. Deposition rate of boron nitride increased with an increase in temperature. After a certain temperature, deposition rate decreased with temperature due to the sintering effect. The highest deposition rate was observed when BNNTs were synthesized with the B/Fe weight ratio of 15/1 at 1300 °
C.
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Wang, Huifeng [Verfasser]. "Surface science approach to catalyst preparation : Palladium deposition onto iron oxide films from the liquid phase / Huifeng Wang." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1029955042/34.

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28

Lally, Michael. "Bodies, bones, objects and stones : investigating infancy, infant death, deposition and human identity in Iron Age Southern England." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/371690/.

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This thesis significantly contributes towards a fuller and more complex appreciation of the formation of human identity in Iron Age Southern England. It constitutes the first doctoral study of infancy, infant death and infant deposition for this region and period, and is the first piece of research to specifically consider infancy as an informer upon the formation of identity at this time. This thesis is structured around four main themes: (1) Was there a concept of infancy in Iron Age southern England? (2) How does infancy inform upon the construction of identity at this time? (3) If present, how did the concept of infancy fit into any perceived understanding of a wider Iron Age life course? (4) Were infants treated in similar ways to older individuals in death? These themes led to the formation of a set of hypothesised research questions. The investigative results offer an important and fresh insight into the nature and construction of identity at this time. Results suggest that infant (and older) bodies and bones were conceptualised and treated in multiple, and often co-existing, ways; many of which appear to have had nothing to do with the formal burial of the ‘person’ per se. Rather, while some bodies were formally buried, many others were perceived and treated in objectified ways. In these instances, human bodies and bones were conceptualised as forms of materiality, perceived and treated in a similar way to animal bodies and bones, objects and environmental materials. Importantly, this thesis provides evidence which suggests that although multiple and complex, in many instances, the conceptual nature of the infant (and older) body, and its subsequent treatment and deposition during this time, may have been underpinned by a uniform and geographically widespread concept of infancy.
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Wang, Hui-Feng [Verfasser]. "Surface science approach to catalyst preparation : Palladium deposition onto iron oxide films from the liquid phase / Huifeng Wang." Berlin : Freie Universität Berlin, 2012. http://nbn-resolving.de/urn:nbn:de:kobv:188-fudissthesis000000039466-3.

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30

Crease, Susheela Marie Elizabeth. "Re-thinking ritual traditions : interpreting structured deposition in watery contexts in Late Pre-Roman Iron Age and Roman Britain." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1466183/.

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This investigation seeks to define the strands of continuity and change in structured deposition across the Late Pre-Roman Iron Age to Early Roman transition in Britain, and interpret their significance in terms of cultural interaction. These interpretations not only examine and re-think structured deposition in relation to ritual traditions, but also explore how the continuity of such traditions was impacted by the transition between these two periods. Metalwork is a central focus but a wide range of other finds are also considered in order to take a holistic perspective on deposition. Watery deposits were an obvious starting point but comparisons with dry context deposits were necessary to provide a more complete understanding of these practices. The data were gathered from a number of individual sites throughout two contrasting case study zones defined by major waterways and labelled as such: the Severn-Thames Axis in the south and the Solway-Forth Axis in the north of Britain. Through the use of site reports as the main source of data, the analysis took a two-tiered approach. Individual episodes of structured deposition were examined and interpreted on a site-by-site basis. This then led to investigations on a broader scale by examining changes in the continuity of practices in the type of finds deposited, the contexts into which deposition took place and pre-deposition practices, such as deliberate breakage to determine patterns of deposition across the case study zones as a whole. With this comparative analysis it can be concluded that watery contexts were not a unique locus of structured deposition, and indeed that this practice is highly diverse across the zones studied. The temporal patterning in this diversity is examined in detail and related to cultural interaction.
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31

Weerasinghe, Hasitha C. "Electrical characterization of metal-to-insulator transition in iron silicide thin films on sillicone substrates." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001677.

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32

Daly, Patrcik. "Social practice and material culture : the use, discard and deposition of ceramic material at two Iron Age hillforts in Oxfordshire." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251444.

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33

Li, Xuefeng. "Marine Iron Biogeochemistry Under a Changing Climate: Impact on the Phytoplankton and the Diazotroph Communities." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/266850.

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Diatoms constitute a major group of phytoplankton, accounting for ~20% of the world’s primary production. Biological dinitrogen (N2) fixation by diazotrophic cyanobacteria has great biogeochemical implications in nitrogen (N) cycling, being the major source of new N input to the oceans and thereby contributing significantly to carbon (C) export production. It has been shown that iron (Fe) can be the limiting nutrient for phytoplankton growth, in particular, in the HNLC (High Nutrient Low Chlorophyll) regions. Iron plays thus an essential role in governing the marine primary productivity and the efficiency of biological carbon pump. Oceanic systems are undergoing continuous modifications at varying rates and magnitudes as a result of changing climate. The objective of our research is to evaluate the effects of global climate change processes (changing dust deposition, ocean acidification and sea-surface warming) on phytoplankton growth, biological N2 fixation, biogeochemical cycles, and the controlling role of Fe within these impacts. Laboratory culture experiments using a marine diatom Chaetoceros socialis were conducted at two temperatures (13 ℃ and 18 ℃) and two carbon dioxide partial pressures (pCO2, 400 µatm and 800 µatm). The present study clearly highlights the effect of ocean acidification on enhancing the release of Fe upon dust deposition. Our results also confirm that being a potential source of Fe, mineral dust provides in addition a readily utilizable source of macronutrients such as phosphorus (P) and silicon (Si). However, elevated atmospheric CO2 concentrations and ocean acidification may also have an adverse impact on diatom growth, causing a decrease in cell size and possible further changes in phytoplankton composition. Meanwhile, increasing temperature and ocean warming may lead to the reduction of diatom production as well as cell size, inducing poleward shifts in the biogeographic distribution of diatoms. Numerous factors can affect the extent of N2 fixation. A better understanding of the major environmental and nutrient controls governing this process is highly required. Iron and/or phosphorus are thought to be limiting factors in most oceanic regions. Special attention has been given to studying the effects of mineral dust deposition which is believed to promote N2 fixation as it increases the availability of both Fe and P. Three laboratory bioassays (+Fe, +P, +Dust) via incubation experiments were performed on Trichodesmium IMS101, an important contributor to marine N2 fixation. Each addition of Fe, P or desert dust was found to stimulate the growth and the N2 fixation activity of Trichodesmium IMS101. Several adaptive nutrient utilization strategies were observed, such as a Fe luxury uptake mechanism, a P-sparing effect and colony formation. In addition, during a field study in the temperate Northeast Atlantic Ocean using natural phytoplankton assemblages, N2 fixation was remarkably stimulated through the addition of dissolved Fe under low temperature and depleted P conditions, highlighting the critical role of Fe. At the time of this study, no Trichodesmium filaments were found in the region of investigation. The diazotrophic community was dominated by the unicellular cyanobacteria symbiont (prymnesiophyte-UCYN-A1) and heterotrophic diazotrophs, therefore suggesting that Fe could be the ultimate factor limiting N2 fixation of these smaller diazotrophs as well. Recently, the effects of ongoing climate change (ocean warming and acidification) on N2 fixation drew much attention, but various studies led to controversial conclusions. Semi-continuous dilution growth experiments were conducted on Trichodesmium IMS101 under future high pCO2 and warming seawater conditions (800 µatm and 28 °C) and compared to the present-day situations (400 µatm and 24 °C). The results indicate that higher pCO2 and therefore ocean acidification may be beneficial for Trichodesmium growth and N2 fixation. However, the present study suggests that Fe or P limitation in oligotrophic seawaters may offset the stimulation induced on Trichodesmium IMS101 due to ocean acidification. In contrast, ocean warming may not play an important role in Trichodesmium growth and N2 fixation with a 4 °C increase from 24 °C to 28 °C. Nevertheless, ocean warming was previously predicted to cause a shift in the geographical distribution of Trichodesmium toward higher latitudes, extending its niche to subtropical regions and potentially reducing its range in tropical ocean basins.Overall, the biological responses of the marine diatom Chaetoceros socialis and the N2-fixing cyanobacteria Trichodesmium IMS101 to several key climate change processes were presented and discussed in this study. These processes included dust deposition, and ocean acidification and warming, which were shown to have a significant impact on oceanic phytoplankton growth, cell size and primary productivity, biological N2 fixation, phytoplankton distribution and community composition. They would thus affect the C, N, P, Si and Fe biogeochemical cycles in various ways. Iron, as one of the most crucial micronutrients for marine phytoplankton, has in particular strong links to climate change and biogeochemical feedback mechanisms.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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34

McNee, Barbara. "The potters' legacy : production, use and deposition of pottery in Kent, from the middle Bronze Age to the early Iron Age." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/367138/.

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The aim of this thesis is to provide a comprehensive study of prehistoric pottery throughout the region of Kent. Research will focus specifically on middle Bronze Age through to early/middle Iron Age pottery, a date range of approximately 1500 to 400 BC. The study of pottery offers a wealth of information relating to many aspects of the past and yet despite this, prehistoric pottery has been under-researched in Kent. A growing number of important pottery assemblages have been excavated and recent development-led archaeology has produced a great deal of new evidence from excavation and evaluation. This offers an important key to understanding the chronology and interpretation of settlement and burial sites. The basis of this study is to analyse pottery assemblages in order to develop an understanding of the societies who produced and consumed the ceramics, and to provide the foundation for a ceramic typological and chronological framework. This was undertaken through the study of some 77,000 pottery sherds from 66 sites across the region. The data was collected from personally recording and illustrating large assemblages of pottery sherds and by using data from ‘grey literature’, published reports and research by a number of pottery specialists. A form type series was devised, which demonstrates the range of pottery types present in Kent from the middle Bronze Age to early/middle Iron Age. A chronological sequence has been tentatively suggested, which is in need of refinement when more radiocarbon dates are available. A fabric series has been created and presents a brief summary of the types of fabrics used to make the vessels. Key areas were studied, namely, the production and distribution of the ceramics across Kent and how this compares to surrounding regions. Changes in both pottery form types and fabrics over 1000 years of potting history are evident and offer insights into the changing nature of social practises and settlement patterns. Consideration of how the ceramics have been deposited may also offer glimpses into the past, and also serve to highlight the complexities of site formation. This study contributes to a growing body of research on the prehistory of Kent. The limitations are also addressed and the scope for further research.
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Falk, Therese. "En Rituell Vardag? : Rumslig strukturering och deponeringsmönster vidjärnåldersbosättningar i centrala Södra England,800-100 BC." Thesis, University of Kalmar, School of Human Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-2380.

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This paper deals with the question of whether the symbolic language of the late Neolithic and middle Bronze Age was transferred from ceremonial monuments and barrows into the domestic sphere in the late Bronze Age. I will consider such elements as doorway orientation, the significance of boundaries and depositional practices to see if Early-Middle Iron Age settlements were indeed a major scene for ritual behaviour.

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36

Zhang, Bo. "Ferritin : mechanistic studies and electron transfer properties /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1533.pdf.

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37

Hannstein, Inga Karolin. "Self-organized formation of metal-carbon nanostructures by hyperthermal ion deposition." Doctoral thesis, [S.l.] : [s.n.], 2006. http://webdoc.sub.gwdg.de/diss/2006/hannstein.

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38

Sporar, Daniel. "Sputter Deposition of Iron Oxide and Tin Oxide Based Films and the Fabrication of Metal Alloy Based Electrodes for Solar Hydrogen Production." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1183481021.

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Thesis (M.S.Ch.E.)--University of Toledo, 2007.
Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science degree in Chemical Engineering." Bibliography: leaves 72-77.
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39

Pyeon, Myeongwhun [Verfasser]. "Morphological and Structural Modification of Silicon, Titanium and Iron Oxides by Plasma Enhanced Chemical Vapor Deposition for Solar Water Splitting / Myeongwhun Pyeon." München : Verlag Dr. Hut, 2019. http://d-nb.info/1178898997/34.

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40

Chen, Ying. "CVD Synthesis of Single-walled Carbon Nanotubes from Selected Catalysts." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1288980540.

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41

Mangan, Carmel Mary. "The sequestration of phosphate by iron phases in the sediments from Lake Rotorua, New Zealand." The University of Waikato, 2007. http://hdl.handle.net/10289/2238.

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A sequential extraction method was used to determine which dominant sedimentary mineral phase was involved in phosphorus retention in the sediments of Lake Rotorua and to verify the importance of iron phases in the role as a phosphorus sink. The observed influence of the experimental conditions upon the extent of phosphate adsorption to various iron phases shows a considerable quantity of phosphorus is present in the reducible phase and in the residual mineral phase. The phosphorus associated with iron(III) oxide phases was released into solution under reducing conditions when ferric iron oxide/oxyhydroxides, including amorphous and poorly crystalline Fe(III) phases, were solubilized. The residual primary and secondary mineral phases remained stable in the sediments until they were exposed to extremely acidic media analogous to strongly reducing conditions. Manganese is not involved in phosphorus retention to the same extent as iron. Aluminium phases present were released from surface complexes with relative ease and also from mineral structures under the prevailing conditions. The results show a strong agreement between aluminium and phosphorus suggesting it is associated with various aluminium phases to some extent. The sediments of Lake Rotorua are rich in organic-bound P which is released when organic material is oxidized under conditions analogous to anaerobic degradation. The degradation of refractory organic material represents a significant source of phosphorus for incorporation into diagenetic minerals forming in oxic and anoxic layers of the sediment. Heavy liquid separation of the sediments concentrated the small quantities of dense minerals into a separate fraction and the presence of iron sulfides could be verified. Three density fractions obtained by this method separated the diatoms (d less than 2.6 g cm-3), the silicates (d greater than 2.6 less than 3.7 g cm-3) and the heavy minerals (d greater than 3.7 g cm-3) present in the sediment sample. In the heavy mineral phase spherulitic framboidal pyrite and rhombohedrial siderite were observed by scanning electron microscopy (SEM). Energy dispersive x-ray fluorescence (XRF) analysis of the framboidal pyrite detected significant fluorescence's for sulphur and iron. The elemental analysis of siderite characterised it as an iron-rich, non-sulfidic particle with no phosphorus fluorescence. Particles were also observed that had a variable morphology to the framboidal pyrite minerals but similar ratio of Fe to S in the XRF spectrum. It is likely they are other stable forms of iron sulfides or pyrites in various stages of diagenetic dissolution. Digestion of the three density fractions shows the heavy mineral phase is significantly enriched in sulfur and in iron confirming the presence of sulfides. The sulfide-forming trace metals are concentrating in the heavy mineral phase but a progressive enrichment of trace metals down core is not found in the results. Many of the trace elements show maximum concentrations in the Tarawera tephra. There is a good agreement between iron and phosphorus in both treatments that implies iron phases are the predominant phosphorus fixers in the sediments of Lake Rotorua. However the identity of the phosphorus sink could not be confirmed by SEM or XRF analysis of the heavy minerals. The most likely explanations for the observed concentrations of iron and phosphorus and enrichment in the heavy mineral fraction are the persistence of the highly insoluble crystalline iron oxyhydroxides (goethite) in reducing sediments or the formation of the reduced iron mineral vivianite. Considering the density of vivianite it would have being taken into the heavy fraction by default which would account for the enrichment demonstrated by the solution analysis.
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Molina, Griggs Alejandro José. "Laser Metal Powder Deposition of Austenitic Stainless Steel on Spheroidal Graphite Cast Iron : A corrosion resistant coating for the Food & Beverage Industry." Thesis, Högskolan Väst, Avdelningen för svetsteknologi (SV), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-13016.

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Spheroidal graphite cast iron is a material widely used in the industry for the manufacturing of all kind of covers and protective casings thanks to its good combination of mechanical properties, processability and cost. When cast iron components are put into service in corrosive environments the most common approach to protect the components is painting them. The protective painting has been found to flake off with time when aggressive washing procedures, such as the ones used in the Food & Beverage industry, are applied several times. In this project, the coating of cast iron with a corrosion resistant AISI 316L stainless steel by Laser Metal Powder Deposition has been studied as an alternative protection against corrosion. Several samples with different combinations of substrate preparation, number of layers and surface conditions were produced and analysed by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, wash down tests and salt spray chamber corrosion tests. Main results show that the diffusion of carbon from the carbon-rich cast iron to the stainless steel coating, which would have a negative effect on the corrosion resistant properties, was significantly low as a result of the low penetration and dilution achieved during the laser metal powder deposition process. The deposited stainless steel coatings successfully protected the substrate during the corrosion tests and the integrity of the coatings is not expected to fail during the washing producers applied in the industry.
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Polteau, Stéphane. "The early proterozoic Makganyene glacial event in South Africa : its implication in sequence stratigraphy interpretations, paleoenvironmental conditions and iron and manganese ore deposition." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1007612.

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The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup in the Griqualand West Basin. It consists of diamictites, sandstones, banded iron-formations (BIFs), shales, siltstones and carbonates. It is generally accepted that the Makganyene Formation rests on an erosive regional unconformity throughout the Northern Cape Province. However this study demonstrates that this stratigraphic relationship is not universal, and conformable contacts have been observed. One of the principal aims of this study is to identify the nature of the Makganyene basal contact throughout the Griqualand West Basin. Intensive fieldwork was carried out from Prieska in the south, to Danielskuil in the north. In the Sishen and Hotazel areas, only borehole material was available to assess the stratigraphy. The Griquatown Fault Zone delimits the boundary between the deep basin and platform facies. The Koegas Subgroup is only present south of the Griquatown Fault Zone, where it pinches out. However, the transition Griquatown BIFs-Koegas Subgroup occurs in lacustrine deposits on the Ghaap platform (Beukes, 1983). The Griquatown Fault Zone represents the edge of the basin, which corresponds to a hinge rather than a fault zone. The Makganyene Formation rests with a conformable contact on the Koegas Subgroup south of the Griquatown Hinge Zone, and north of it the Makganyene Formation lies unconformably on the Asbestos Hills Subgroup. The Makganyene Formation displays lateral facies changes that reflect the paleogeography of the Griqualand West Basin, and the development of ice sheets/shelves. The Ghaap platform is characterised by coarse immature sand interbedded with the diamictites. The clasts in this area contain local Asbestos Hills material and no dropstones are present. Such settings are typical of sediments that are being deposited below a grounded ice mass. At the Griquatown Hinge Zone, the sandstone lenses are smaller, and the clasts consist of chert, of which a great number are striated and faceted. In the Matsap area, the presence of dropstones is strong evidence for the presence of a floating ice shelf that released its material by basal melting. Further south, the Makganyene Formation contains stromatolitic bioherms that only form if clastic contamination is minimal and therefore the ice that transported the detritus to the basin did not extend far into open sea conditions. The base of the Hotazel Formation also contains diamictite levels. Dropstones have been identified, implying a glacial origin. The Hotazel diamictites are interbedded with hyaloclastites and BIFs. The Makganyene glacial event, therefore, was not restricted to the Makganyene Formation, but also included the Ongeluk Formation, through to the base of the Hotazel Formation. Petrographic studies of the Makganyene Formation and the base of the Hotazel Formation reveal mineral assemblages that are diagnostic of early to late diagenetic crystallisation and of low-grade metamorphism not exceeding the very low green-schist facies. The facies identified display the same sense of basin deepening, from shallow high-energy Hotazel area on the Ghaap platform, to the deep basin in the Matsap area. Whole-rock geochemical analyses reveal that the elemental composition of the Makganyene Formation is very similar to that of the Asbestos Hills BIFs, which were the most important source of clastic detritus for the Makganyene Formation. However, minor amounts of carbonates of the Campbellrand Subgroup, as well as a felsic crustal input from the Archean granitoid basement, made contributions. On the Ghaap platform, the Makganyene diamictite is enriched in iron, calcium, and magnesium, while in the deeper parts of the basin the diamictites are enriched in detrital elements, such as titanium and aluminium, which occur in the fine clay component. The Hotazel diamictite displays a distinct mafic volcanic input, related to the extrusion of the Ongeluk basaltic andesites, which was incorporated in the glacial sediments. Sequence stratigraphy is based on the recognition of contacts separating the different systems tracts that compose a depositional sequence. However, because the basal contact of the Makganyene Formation has not been properly identified in previous work, no correct model has been proposed so far. Therefore correlations between the Griqualand West and the Transvaal basins, based on lithostratigraphic similarities and extrapolations of unconformities, have to be reviewed, especially since the publication of new radiometric ages contradict all previously proposed correlations. It is proposed here that the Transvaal Supergroup in the Griqualand West Basin represents a continuous depositional event that lasted about 200 Ma. The Makganyene glacial event occurred during changing conditions in the chemistries of the atmosphere and ocean, and in the continental configuration. A Snowball Earth event has been proposed as the causative process of such paleoenvironmental changes. However, evidence presented here of less dramatic glacial conditions, with areas of ice-free waters, implies an alternative to the Snowball Earth event. The paleoenvironmental changes are thought to represent a transition from an anaerobic to aerobic atmosphere, that was responsible for the global cooling of the surface of the Earth, Such a glacial event may have aided in the large-scale precipitation of iron and manganese in areas of intense upwellings.
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44

Reidhead, Joshua Glen. "Significance of the Rates of Atmospheric Deposition Around Utah Lake and Phosphorus-Fractionation of Local Soils." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7685.

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Eutrophic Utah Lake receives a large nutrient load from a variety of sources, includingtreated wastewater discharges, runoff and tributaries, recycling from bottom sediments andAtmospheric Deposition (AD). AD was the focus of this study and was comprised of twocomplementary parts. First was a study of nitrogen and phosphorus depositions from theatmosphere, and second was a study of phosphorous as contained in soils near Utah Lake viafractionation methods.The soil samples were found to contain approximately 1,000 mg-P/kg soil for totalphosphorus (TP). A separate phosphorus (P) fractionation gave slightly higher values, excludingthe residual P, we are 95% confident that one gram of sample soil contains between 2.2 and 4.3percent water soluble P, 0.6 to 1.1 percent loosely-bound P, 2.5 to 4.4 percent aluminum andiron-bound P, and 90.7 to 94.2 percent calcium-bound P.AD results indicate that during the period from April 1 to Nov 17, 2018, Utah Lakereceived approximately 58 tons of soluble reactive P, 153 tons of TP, 118 tons of nitrogen (N)from nitrate, and 387 tons of N from ammonium via AD.Nutrient quantities from AD are very large compared to the 17 ton/yr of P needed for aeutrophic loading to the lake. Because of the very large overall nutrient loading to Utah Lake, itis likely that some other limiting growth factors are controlling algal growth.
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45

Fondell, Mattis. "Synthesis and Characterisation of Ultra Thin Film Oxides for Energy Applications." Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-232948.

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This thesis describes studies of materials which can be exploited for hydrogen production from water and sunlight. The materials investigated are maghemite (γ-Fe2O3), magnetite (Fe3O4) and especially hematite (α-Fe2O3), which is an iron oxide with most promising properties in this field. Hematite has been deposited using Atomic Layer Deposition (ALD) - a thin-film technique facilitating layer-by-layer growth with excellent thickness control and step coverage. The iron oxides were deposited using bis-cyclopentadienyl iron (Fe(Cp)2) or iron pentacarbonyl (Fe(CO)5) in combination with an O2 precursor. Since it is crucial to have good control of the deposition process, the influence of substrate, process temperature, precursor and carrier gas have been investigated systematically. By careful control of these deposition parameters, three polymorphs of iron oxide could be deposited: hematite (α-Fe2O3), maghemite (γ-Fe2O3) and magnetite (Fe3O4). The deposited materials were characterized using X-ray Diffraction, Raman and UV-VIS Spectroscopy, and Scanning Electron Microscopy. Hard X-ray Photoelectron Spectroscopy (HAXPES) was also used, since it is a non-destructive, chemically specific, surface sensitive technique – the surface sensitivity resulting from the short mean escape depth of the photoelectrons. The depth probed can be controlled by varying the excitation energy; higher photoelectron energies increasing the inelastic mean-free-path in the material. HAXPES studies of atomic diffusion from F-doped SnO2 substrates showed increased doping levels of Sn, Si and F in the deposited films. Diffusion from the substrate was detected at annealing temperatures between 550 °C and 800 °C. Films annealed in air exhibited improved photocatalytic behavior; a photocurrent of 0.23 mA/cm2 was observed for those films, while the as-deposited hematite films showed no photo-activity whatsoever. The optical properties of low-dimensional hematite were studied in a series of ultra-thin films (thicknesses in the 2-70 nm range). The absorption maxima were shifted to higher energies for films thinner than 20 nm, revealing a different electronic structure in thin films.
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Lindgren, Fredrik. "Lakes are browner in the south than in the north of Sweden despite similar levels of dissolved iron." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-39845.

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During recent decades many lakes have become browner in the northern hemisphere and more specific in Sweden. This process is called brownification. Brownification of lakes makes it more difficult to clean water to drinking water and may have negative ecological effects on biota. Browning of lakes is generally thought to be caused by an increase of humic substances that consist of organic matter which colour the water brown or yellow. However, more recent studies show that dissolved iron can interact with humic substances in browning lakes. Since the concentrations of dissolved iron have increased during recent years and the mechanisms behind brownification and the contribution of iron to this process is not clearly understood it is important to investigate this subject. In this study 17 lakes in south of Sweden were sampled for iron concentration, dissolved organic carbon (DOC), absorbance (420nm) and pH. Further, data was added about atmospheric sulphur deposition and additional data from 17 lakes in the north part of Sweden. Iron had a stronger significant correlation towards absorbance than DOC had in the south of Sweden. A similar amount of dissolved iron seems to colour lakes differently based on their location in Sweden. This indicates that different mechanisms are involved in the interaction between iron and absorbance. However, pH had a stronger relationship with absorbance than either DOC or iron. Overall results suggested that iron do have a strong browning effect on Swedish fresh water lakes in the presence of DOC and that iron-increase driven processes may be due to a change of pH.
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47

Frisk, Mattias. "Concerning Mass Graves : The use, development and identities within mass graves during the Scandinavian Iron age and Middle ages." Thesis, Uppsala universitet, Institutionen för arkeologi och antik historia, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-243653.

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This master thesis deals with the subject of mass graves as a result of war and violence; how, where and why they are created, what they represent and how they are used throughout the Scandinavian Iron Age and Middle Ages. To analyze and discuss these questions, I have used nine case studies as well as several literary sources such as Beowulf, Tacitus and Jordanes. To further increase the depth of this discussion and to help us understand the mass graves themselves, I have also included subject of warfare in the form of a walkthrough of violence and social psychology. Together, these pieces have helped me form the basis for an analysis and discussion of the three acts I have created: The Ingroup act of deposition, The Outgroup act of deposition and the Triumph act of deposition.
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48

Nilsson, Erik A. A. "Degradation Mechanisms of Heat Resistant Steel at Elevated Temperatures : In an Iron Ore Pelletizing Industry." Doctoral thesis, Luleå tekniska universitet, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62162.

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This thesis focuses on the different degradation mechanisms of the stainless steel in a travelling grate in a Grate-Kiln iron ore pellet indurator. The travelling grate is a conveyor belt that transports green-body pellets to a rotary kiln while the pellets are being dried and pre-heated to a temperature of 900-1100 °C by recycled hot air. After unloading of the pellets to the rotary-kiln for further sintering, the travelling grate is cooled in room temperature while returning to the loading zone of the wet pellets. The steel was tested during thermal cycling in a test-rig, in order to simulate the influence of thermo mechanical fatigue and oxide spallation. The influence of erosion-deposition was investigated in a modified horizontal industrial combustion kiln at 800 °C, with slag and coal from production used as erosive media and combustion fuel, respectively. The influence of minor alloying additions of Mn, Si and Ti on the microstructure was explored by eight different casted alloy compositions. Isothermal heat treatments were performed at 800 °C during 200 hours on steel immersed in deposits recovered from a travelling grate in production. The three main degradation mechanisms found in this work are thermal spallation, erosion-deposition and deposit induced accelerated corrosion (DIAC). Thermal spallation of the oxide layer is caused by the thermal expansion difference between the oxide and the metal during heating and cooling. It has been found that Ti improves the spallation resistance while Si reduces it. Spallation of deposits is another cause believed to increase the degradation. Erosion-deposition appears due to simultaneous erosion and deposition of particles on the travelling grate that causes erosion or deposition depending on the amount of alkali metals in the environment. The velocity of the particles also influences erosion and deposition in the way that higher velocities increase erosion. DIAC is proposed to form on the travelling grate due to the concentration of chloride- and sulphate containing alkali metals in the deposits.  Other than these major degrading mechanisms, minor degradation mechanisms such as internal oxidation, sigma formation, carburization and sensitization towards inter-granular attack have been found inside the steel during heating. Thermo mechanical fatigue (TMF) causes intergranular cracks in the material of the travelling grate. Casting issues such as micro-segregation have also been addressed in this thesis. A few different ways to improve degradation resistance have been proposed, such as homogenization heat treatments, optimization of process parameters and inhibitor solutions.
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49

Tinoco, José. "On the Spray Forming of Metals, the Formation of Porosity and the Heat Evolution during Solidification." Doctoral thesis, KTH, Casting of Metals, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3636.

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This thesis deals with the heat evolution duringsolidification and its relation to the formation of porosity.It intends to improve the current understanding of theformation of porosity in cast materials with special interestin nodular cast iron and the spray forming process. Twodifferent systems, a Fe-based alloy, Cast iron, and a Ni-basedalloy, Inconel 625, are examined. The effect on the heatevolution of the morphology and the processing parameters inspray forming are treated.

An evaluation of the microstructural features, segregationbehavior and physical properties such as latent heat of fusionis performed byusing thermal analysis under cooling ratesranging from 0.1 to 104 K/s. In order to achieve this amodified differential thermal analysis (DTA) equipment, amirror furnace and levitation casting are used. Results arepresented in terms of the fraction of solidified, the coolingrate and the microstructure observed. The measured latent heatof fusion is not constant throughout the solidificationprocess. Variations in morphology and cooling rate affect therelease of the latent heat.

A thermodynamic model is used to describe the experimentalobservations and to explain the formation of pores in nodularcast iron by taking into consideration the formation of latticedefects during the liquid/solid transformation. In this casethe formation of porosity is regarded as a consequence ofchanges in the volume fraction ratio graphite/ during thesolidification process.

A numerical model of the spray forming process is developedby means of CFD modelling and compared with experimentalmeasurements performed in an industrial facility. Stagnationpressure measurements provided information about the gas flowvelocity and an analysis of the overspray powder providedinformation about the particle thermal history. Evaluation ofthe deposit was also performed. It is observed that the processconditions in spray forming promote non-equilibriumsolidification even though solidification at the deposit occursat a lower rate. In this case the porosity formed near theinterface substrate/deposit depends largely on the substratetemperature. The presence of certain reactive elements, such astitanium, affects the porosity levels in the rest of thedeposit.

Keywords:Thermal Analysis, Nodular Cast Iron, Inconel625, CFD, Flow Assesment, Multiphase Flow, Spray Deposition,Microporosity, Superalloys

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50

Butterfield, Martin Thomas. "Surface structure of ultrathin metal films deposited on copper single crystals." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/33132.

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Ultrathin films of Cobalt, Iron and Manganese have been thennally evaporated onto an fcc Copper (111) single crystal substrate and investigated using a variety of surface structural teclmiques. The small lattice mismatch between these metals and the Cu (111) substrate make them an ideal candidate for the study of the phenomena of pseudomorphic film growth. This is important for the understanding of the close relationship between film structure and magnetic properties. Growing films with the structure of their substrate rather than their bulk phase may provide an opportunity to grow materials with novel physical and magnetic properties, and hence new technological applications. Both Cobalt and Iron have been found to initially maintain a registry with the fee Cu (111) surface in a manner consistent with pseudomorphic growth. This growth is complicated by island rather than layer-by-layer growth in the initials stages of the film. In both cases a change in the structure of the film seems to occur at a point where the coalescence of islands in the film may be expected to occur. When the film does change structure they do not form a perfect over-layer with the structure of their bulk counterpart. The films do contain a number of features representative of the bulk phase but also contain considerable disorder and possibly remnants of fcc (111) structure. The order present in these films can be greatly improved by annealing. Manganese appears to grow with an fee Mn (111) lattice spacing and there is no sign of a change in structure in films of up to 4.61 ML thick. The gradual deposition and annealing of a film to 300°C, with a total deposition time the same as that for a 1 ML thick film, causes a surface reconstruction to occur that is apparent in a R30° (√3×√3) LEED pattern. This is attributed to the formation of a surface alloy, which is also supported by the local expansion of the Cu lattice in the (111) direction.
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