Dissertations / Theses: 'Metalic Art'

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Choudhury, Anamika. "Traditional art and craft of Sub- Himalayan Darjeeling: historical study." Thesis, University of North Bengal, 2019. http://ir.nbu.ac.in/handle/123456789/4026.

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VAZ, GUILHERME DEMBERG. "QUANTIFICATION OF METALLIC IRON LOSSES IN ELECTRIC ARC FURNACE SLAGS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18624@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
A metalurgia é a ciência que estuda os diversos meios para a transformação dos metais em materiais úteis à sociedade. A metalurgia do ferro representa a maior fatia da aplicação dos metais. Por ser tão representativa é chamada de Siderurgia. Dentre as diversas rotas para a transformação do ferro em aço, as usinas semi-integradas apresentam um forte apelo ecológico, pois utilizam a sucata, oriunda da reciclagem de ferro, e o ferro gusa como matérias-primas para a fusão no Forno Elétrico a Arco. Naturalmente, em todo processo industrial há a geração de resíduos e, neste caso, o principal é a escória, composta de óxidos formados e adicionados ao longo da fusão. Seus principais constituintes são: CaO, SiO2, FeO, MnO, MgO, Al2O3 e P2O5. No entanto, ainda há a presença de Ferro Metálico, um fato indesejável, pois atua negativamente no rendimento metálico e, consequentemente, aumenta o custo do aço. Toda escória gerada é beneficiada com o intuito de recuperar a parte metálica. Este material beneficiado retorna para as usinas como sucata metálica, contendo teores definidos de ferro metálico. O teor de ferro presente na sucata recuperada é avaliado pelas empresas processadoras de escória de maneira indireta por um ensaio de densidade específica. Havia dúvidas se a sucata recuperada da escória do forno apresentava teores de ferro que justificasse seu emprego como matéria-prima ferrosa. Assim sendo, foi proposta uma rota de processamento capaz de mensurar o teor de ferro presente e permitir a comparação com os teores obtidos com o ensaio de densidade. Os resultados mostram que i) é possível calcular o impacto no rendimento, ii) que as sucatas recuperadas apresentam valores inferiores ao esperado, iii) que a equação de densidade superestima o teor de ferro e iv) que modificações propostas nos coeficientes da equação vigente melhoram seu grau de assertividade. Estes resultados foram comprovados em 3 plantas siderúrgicas.
Metallurgy is the science that studies the various processes for the transformation of metals into society useful materials. The iron metallurgy represents the largest body of the metals application, hence it is called Steel industry. Among the various routes for the transformation of iron into steel, semiintegrated plants have a strong ecological appeal due to their extensive use of scrap, derived from the recycling of iron, and pig iron as raw materials for the Electric Arc Furnace. Of course, industrial processes generate waste. The major waste of the Electric Arc Furnace is the slag, a mixture of oxides produced during the process, containing CaO, SiO2, FeO, MnO, MgO, Al2O3 e P2O5. However, there is also the presence of metallic iron, a fact undesirable, because it acts negatively on the metallic yield and therefore increases the cost of steel. All slag generated is processed in order to recover the metallic iron. The slag beneficiation returns to the mills a material containing defined levels of iron. The content of recovered iron is assessed by slag processing companies indirectly by a specific gravity test. There have been doubts whether the recovered scrap iron content justify its use as raw ferrous materials. Therefore, it is proposed a processing route capable of measuring the amount of iron present in the recovered scrap. The measured iron content is also compared with the levels obtained from the test density. The results show that i) it is possible to calculate the impact on iron yield, ii) the recovered iron content is lower than expected, iii) the density equation overestimates the amount of iron and iv) a correction is proposed to improve the assertiveness of the density equation. Three steel plants confirmed the results from this research.

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Corkery, Robert, and robert corkery@anu edu au. "Artificial biomineralisation and metallic soaps." The Australian National University. Research School of Physical Sciences and Engineering, 1998. http://thesis.anu.edu.au./public/adt-ANU20080124.190014.

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In this thesis, geometry is used as a basis for conducting experiments aimed at growing and arranging inorganic minerals on curved interfaces. Mineralisation is directed using crystalline and liquid-crystalline metallic soaps and surfactant/water systems as templates.¶ A review of the history, syntheses, structure and liquid crystallinity of metallic soaps and other amphiphiles is presented as a foundation to understanding the interfacial architectures in mesostructured template systems in general.¶ In this study, a range of metallic soaps of varying chain length and cation type are synthesised and characterised to find potentially useful templates for mineral growth. These include alkaline-earth, transition metal, heavy metal and lanthanide soaps. These are systematically characterised using a variety of analytical techniques, including chemical analyses, x-ray diffraction (XRD) infrared spectroscopy (IR) and differential scanning calorimetry (DSC). Their molecular and crystal structures are studied using transmission electron microscopy (TEM), cryo-TEM, electron diffraction (ED), electron paramagnetic spin resonance (EPR), absorption spectroscopy (UV-VIS), high resolution laser spectroscopy, atomic force microscopy (AFM), nuclear magnetic resonance spectroscopy, scanning electron microscopy (SEM), electron dispersive x-ray analysis (EDXA), thermal gravimetric analysis (TGA) and magnetic measurements. Models for the molecular and crystal structures of metallic soaps are proposed. The soaps are predominantly lamellar crystalline or liquid crystalline lamellar rotor phases with tilted and/or untilted molecular constituents. These display evidence of varying degrees of headgroup organisation, including superstructuring and polymerisation. A single crystal structure is presented for a complex of pyridine with cobalt soap. Simple models for their structure are discussed in terms of their swelling properties in water and oils. Experiments are also presented to demonstrate the sorbent properties of aluminium soaps on oil spills.¶ The thermotropic liquid crystallinity of alkaline earth, transition metal, heavy metal and lanthanide soaps is investigated in detail. This is done to assess their suitability as templates, and to document their novel thermotropic behaviour, particularly the relatively unknown lanthanide soaps. Liquid crystalline behaviours are studied using high-temperature XRD (HTXRD), hot-stage optical microscopy and DSC. Models for a liquid crystalline phase progression from crystals to anisotropic liquids are discussed in terms of theories of self-assembly and interfacial curvature. The terminology required for this is drawn from various nomenclature systems for amphiphilic crystals and liquid crystals. General agreement with previous studies is reported for known soaps, while liquid crystallinity is demonstrated in the lanthanide and some non-lanthanide soaps for the first time. A general phase progression of crystalline lamellar through liquid crystalline lamellar to non-lamellar liquid crystalline is discussed in terms of models concerned with the molecular and crystal structures of the soaps and their phase transitions via headgroup and chain re-arrangements.¶ Experiments aimed at guiding growth of metal sulfides using metallic soaps as templates are described, and a model for this growth is discussed. Metal sulfides have been successfully grown by reacting crystalline and liquid crystalline transition metal and heavy metal soaps with H2S gas at room temperature and at elevated temperature. These have been characterised using XRD, TEM, ED and IR. Sulfide growth is demonstrated to be restricted and guided by the reacting soap template architecture. Zinc, cadmium, indium and lead soaps formed confined nanoparticles within the matrix of their reacting soap template. In contrast, curved and flat sheet-like structures, some resembling sponges were found in the products of sulfided iron, cobalt, nickel, copper, tin and bismuth soaps. A model to explain this behaviour is developed in terms of the crystal and liquid crystal structures of the soaps and the crystal structures of the metal sulfide particles.¶ Liquid crystalline iron soaps have been subjected to controlled thermal degradation yielding magnetic iron oxide nanoparticles. Some XRD and TEM evidence has been found for formation of magnetic mesostructures in heat-treated iron soaps. Models for the molecular and liquid crystalline structure of iron soaps, their thermotropic phase progression and eventual conversion to these magnetic products are discussed. Systematic syntheses of mesoporous silicates from sheeted clays are discussed.¶The templates that have been used are cationic surfactants and small, organic molecular salts. Experiments are reported where a cooperative self-assembly of surfactant/water/kanemite plus or minus salt and oils yields 'folded sheet materials' (FSM'S). Templating of kanemite has also been achieved using cobalt cage surfactants. A theoretical prediction of the specific surface areas and specific volumes of homologous sets of FSM's gave excellent agreement with measured values. The geometry and topology of the mesostructures are discussed. A theoretical model is also discussed regarding the curvature found in the sheets of natural clays , and results of templating clays and silica using metallic soaps are presented. Experiments and a model for low temperature nucleation and growth of microporous silicalite-1 are described in terms of silica templating by water clathrates.¶ Finally, the problem of finding minimal surface descriptions of crystal networks is addressed. Combinatoric methods are used to disprove the existence of possible embeddings of type I and II clathrate networks in non-self intersecting periodic minimal surfaces. The crystal network of the clathrate silicate, melanophlogite is successfully embedded in the WI-10 self-intersecting surface. Details of a previously unreported, genus-25 periodic surface with symmetry Im3m are discussed.

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Vadlakonda, Suman. "Indentation induced deformation in metallic materials." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4904/.

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Nanoindentation has brought in many features of research over the past decade. This novel technique is capable of producing insights into the small ranges of deformation. This special point has brought a lot of focus in understanding the deformation behavior under the indenter. Nickel, iron, tungsten and copper-niobium alloy system were considered for a surface deformation study. All the samples exhibited a spectrum of residual deformation. The change in behavior with indentation and the materials responses to deformation at low and high loads is addressed in this study. A study on indenter geometry, which has a huge influence on the contact area and subsequently the hardness and modulus value, has been attempted. Deformation mechanisms that govern the plastic flow in materials at low loads of indentation and their sensitivity to the rate of strain imparted has been studied. A transition to elastic, plastic kind of a tendency to an elasto-plastic tendency was seen with an increase in the strain rate. All samples exhibited the same kind of behavior and a special focus is drawn in comparing the FCC nickel with BCC tungsten and iron where the persistence of the elastic, plastic response was addressed. However there is no absolute reason for the inconsistencies in the mechanical properties observed in preliminary testing, more insights can be provided with advanced microscopy techniques where the study can be focused more to understand the deformation behavior under the indenter. These experiments demonstrate that there is a wealth of information in the initial stages of indentation and has led to much more insights into the incipient stages of plasticity.

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Sandberg, Erik. "Energy and scrap optimisation of electric arc furnaces by statistical analysis of process data." Licentiate thesis, Luleå, 2005. http://epubl.luth.se/1402-1757/2005/21.

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Mridha, Sanghita. "Structure Evolution and Nano-Mechanical Behavior of Bulk Metallic Glasses and Multi-Principal Element Alloys." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984260/.

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Bulk metallic glasses and multi-principal element alloys represent relatively new classes of multi-component engineering materials designed for satisfying multiple functionalities simultaneously. Correlating the microstructure with mechanical behavior (at the microstructural length-scales) in these materials is key to understanding their performance. In this study, the structure evolution and nano-mechanical behavior of these two classes of materials was investigated with the objective of fundamental scientific understanding of their properties. The structure evolution, high temperature nano-mechanical behavior, and creep of two Zr-based alloys was studied: Zr41.2Ti13.8Cu12.5Ni10.0Be22 (Vitreloy1) and Zr52.5Ti5Cu17.9Ni14.6All0 (Vitreloy105). Devitrification was found to proceed via the formation of a metastable icosahedral phase with five-fold symmetry. The deformation mechanism changes from inhomogeneous or serrated flow to homogenous flow near 0.9Tg, where Tg is the glass transition temperature. The creep activation energy for Vitreloy1 and Vitreloy105 were 144 kJ/mol and 125 kJ/mol, respectively in the range of room temperature to 0.75Tg. The apparent activation energy increased drastically to 192 kJ/mol for Vitreloy1 and 215 kJ/mol for Vitreloy105 in the range of 0.9Tg to Tg, indicating a change in creep mechanism. Structure evolution in catalytic amorphous alloys, Pt57.5Cu14.7Ni5.3P22.5 and Pd43Cu27Ni10P20, was studied using 3D atom probe tomography and elemental segregation between different phases and the interface characteristics were identified. The structure evolution of three multi-principal element alloys were investigated namely CoCrNi, CoCrFeMnNi, and Al0.1CoCrFeNi. All three alloys formed a single-phase FCC structure in as-cast, cold worked and recrystallized state. No secondary phases precipitated after prolonged heat treatment or mechanical working. The multi-principal element alloys showed less strain gradient plasticity compared to pure metals like Ni during nano-indentation. This was attributed to the highly distorted lattice which resulted in lesser density of geometrically necessary dislocations (GNDs). Dislocation nucleation was studied by low load indentation along with the evaluation of activation volume and activation energy. This was done using a statistical approach of analyzing the "pop-in" load marking incipient plasticity. The strain rate sensitivity of nanocrystalline Al0.1CoCrFeNi alloy was determined by in situ compression of nano-pillars in a Pico-indenter. The nanocrystalline alloy demonstrated a yield strength of ~ 2.4 GPa, ten times greater than its coarse grained counterpart. The nanocrystalline alloy exhibited high strain rate sensitivity index of 0.043 and activation volume of 5b3 suggesting grain boundary dislocation nucleation.

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Garrison, Seth Thomas. "Catalytic Properties and Mechanical Behavior of Metallic Glass Powders." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984273/.

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Lack of crystalline order and microstructural features such as grain/grain-boundary in metallic glasses results in a suite of remarkable attributes including very high strength, close to theoretical elasticity, high corrosion and wear resistance, and soft magnetic properties. By altering the morphology and tuning of composition, MGs may be transformed into high-performance catalytic materials. In this study, the catalytic properties of metallic glass powders were demonstrated in dissociating toxic organic chemicals such as AZO dye. BMG powders showed superior performance compared to state of the art crystalline iron because of their high catalytic activity, durability, and reusability. To enhance the catalytic properties, high energy mechanical milling was performed to increase the surface area and defect density. Iron-based bulk metallic glass (BMG) of composition Fe48Cr15Mo14Y2C15B6 was used because of its low cost and ability to make large surface area by high energy ball milling. AZO dye was degraded in less than 20 minutes for the 9 hours milled Fe-BMG. However, subsequent increase in ball milling time resulted in devitrification and loss of catalytic activity as measured using UV-Visible spectroscopy. Aluminum-based bulk metallic glass (Al-BMG) powder of composition Al82Fe3Ni8Y7 was synthesized by arc-melting the constituent elements followed by gas-atomization. The particle size and morphology were similar to Fe-BMG with a fully amorphous structure. A small percentage of transition metal constituents (Fe and Ni) in a mostly aluminum alloy showed high catalytic activity, with no toxic by-products and no change in surface characteristics. Al-alloy particles, being light-weight, were easily dispersed in aqueous medium and accelerated the redox reactions. The mechanism of dye dissociation was studied using Raman and Infrared (IR) spectroscopy. Breaking of -C-H- and - C-N- bonds of AZO dye was found to be the primary mechanism. Mechanical behavior of individual BMG particles was evaluated by in situ pico-indentation in a scanning electron microscope (SEM) to understand the fracture mechanisms. Catastrophic shear banding was found to be the primary fracture mode, which supported the observation of flake formation during high energy ball milling.

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Samuel, Sonia. "Surface Engineering and Characterization of Laser Deposited Metallic Biomaterials." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3618/.

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Novel net shaping technique Laser Engineered Net shaping (LENS) laser based manufacturing solution (Sandia Corp., Albuquerque, NM); Laser can be used to deposit orthopedic implant alloys. Ti-35Nb-7Zr-5Ta (TNZT) alloy system was deposited using LENS. The corrosion resistance being an important prerequisite was tested electrochemically and was found that the LENS deposited TNZT was better than conventionally used Ti-6Al-4V in 0.1N HCl and a simulated body solution. A detailed analysis of the corrosion product exhibited the presence of complex oxides which are responsible for the excellent corrosion resistance. In addition, the in vitro tests done on LENS deposited TNZT showed that they have excellent biocompatibility. In order to improve the wear resistance of the TNZT system boride reinforcements were carried out in the matrix using LENS processing. The tribological response of the metal matrix composites was studied under different conditions and compared with Ti-6Al-4V. Usage of Si3N4 balls as a counterpart in the wear studies showed that there is boride pullout resulting in third body abrasive wear with higher coefficient of friction (COF). Using 440C stainless steel balls drastically improved the COF of as deposited TNZT+2B and seemed to eliminate the effect of “three body abrasive wear,” and also exhibited superior wear resistance than Ti-6Al-4V.

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Emms, Rachel. "Live underground heavy metal : the perseverance and decline of an Art World." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/live-underground-heavy-metal-the-perseverance-and-decline-of-an-art-world(aabd427c-5cde-4ac7-a3bf-9c3387818935).html.

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Through the lens of underground heavy metal, this thesis explores the importance of live music and the ways in which music worlds transform, decline and remain resilient. In a departure from traditional academic studies of heavy metal, which focus on notions of youth, rebellion, gender and subversive themes, (Weinstein, 1999; Krenske and McKay, 2000; Bennett, 2001), this thesis takes a novel approach in exploring the active nature of this music world. As artists face problems with digital distribution and the related decline of record sales, live music was expected to flourish, as artists seek to compensate for lost recording revenue through live shows. However, this world is not as straightforward as it might appear; arguably it is an industry which is becoming increasingly volatile. As grass-roots venues close and touring costs increase for artists, underground live music faces a particularly tough struggle. Therefore, in contributing to the growing body of literature on 'Art Worlds', (Becker, 1982), this thesis develops an understanding of the ways in which venues, promoters and audiences attempt to sustain this music world. Through surveying attendance at live events and interviewing active participants, it is argued that whilst this music world suggests elements of decline it also shows perseverance. Through the development of translocal networks and maintenance of community, these participants pool resources in order to facilitate live events; even in the face of tremendous struggle. In doing so, this thesis makes a unique contribution to academic understandings of underground metal, capturing this music world at a particularly tumultuous time.

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Ayyagari, Venkata Aditya. "Effect of Alloy Composition, Free Volume and Glass Formability on the Corrosion Behavior of Bulk Metallic Glasses." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822824/.

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Bulk metallic glasses (BMGs) have received significant research interest due to their completely amorphous structure which results in unique structural and functional properties. Absence of grain boundaries and secondary phases in BMGs results in high corrosion resistance in many different environments. Understanding and tailoring the corrosion behavior can be significant for various structural applications in bulk form as well as coatings. In this study, the corrosion behavior of several Zr-based and Fe-Co based BMGs was evaluated to understand the effect of chemistry as well as quenched in free volume on corrosion behavior and mechanisms. Presence of Nb in Zr-based alloys was found to significantly improve corrosion resistance due to the formation of a stable passive oxide. Relaxed glasses showed lower rates compared to the as-cast alloys. This was attributed to lowering of chemical potential from the reduced fraction of free volume. Potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) techniques helped in quantifying the corrosion rate and polarization resistance. The effect of alloy composition was quantified by extensive surface analysis using Raman spectroscopy, energy dispersive x-ray spectroscopy and auger spectroscopy. Pitting intensity was higher in the as-cast glasses than the relaxed glasses. The electrochemical behavior of a Zr-Ti-Cu-Ni-Be bulk metallic glass subjected to high strain processing was studied. High strain processing caused shear band formation and an increase in the free volume. Potentiodynamic polarization and EIS showed a strong correlation between the enthalpy of structural relaxation and corrosion rate and polarization resistance. Pitting was observed to preferentially occur on shear bands in the processed samples, while it was stochastic in unprocessed glass. The corrosion analysis of Co-Fe glasses showed an increase in corrosion current density when Fe content was increased from 0 to 7 at%. The corrosion resistance improved when Fe content was further increased to 15 at%. Similar trend was seen in EIS studies. The improved corrosion resistance at 15 at% Fe can be attributed to the large supercooled region that facilitates the formation of completely amorphous alloy, in contrast to lower Fe containing alloys, where short range ordering may deteriorate the corrosion resistance. Porous metallic glass structure was developed by electrochemical dealloying via cyclic voltammetry. Mechanical properties and changes in electrical conductivity were measured as a function of depth from surface by nano-indentation and nano electrical contact resistance technique. The nanoporous layer was found have hardness of 0.41 GPa and elastic modulus of nearly 22 GPa. The resistivity of the nanoporous layer continuously decreased when moving towards the substrate as the indentation depth increased which is attributed to the gradient in pore size.

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Veligatla, Medha. "Glass Forming Ability, Magnetic Properties, and Mechanical Behavior of Iron-Based and Cobalt-Based Metallic Glasses." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699947/.

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Lack of crystalline order and microstructural features such as grain/grain-boundary in metallic glasses results in a suite of remarkable attributes including very high strength, close to theoretical elasticity, high corrosion and wear resistance, and soft magnetic properties. In particular, low coercivity and high permeability of iron and cobalt based metallic glass compositions could potentially lead to extensive commercial use as magnetic heads, transformer cores, circuits and magnetic shields. In the current study, few metallic glass compositions were synthesized by systematically varying the iron and cobalt content. Thermal analysis was done and included the measurement of glass transition temperature, crystallization temperature, and the enthalpies of relaxation and crystallization. Magnetic properties of the alloys were determined including saturation magnetization, coercivity, and Curie temperature. The coercivity was found to decrease and the saturation magnetization was found to increase with the increase in iron content. The trend in thermal stability, thermodynamic properties, and magnetic properties was explained by atomic interactions between the ferromagnetic metals and the metalloids atoms in the amorphous alloys. Mechanical behavior of iron based metallic glasses was evaluated in bulk form as well as in the form of coatings. Iron based amorphous powder was subjected to high power mechanical milling and the structural changes were evaluated as a function of time. Using iron-based amorphous powder precursor, a uniform composite coating was achieved through microwave processing. The hardness, modulus, and wear behavior of the alloys were evaluated using nano-indentation.

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Willis, Darrin. "Design and development of a novel lightweight long-reach composite robotic arm." Thesis, UOIT, 2009. http://hdl.handle.net/10155/27.

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Metallic robotic arms, or manipulators, currently dominate automated industrial operations, but due to their intrinsic weight, have limited usefulness for large-scale applications in terms of precision, speed, and repeatability. This thesis focuses on exploring the feasibility of using polymeric composite materials for the construction of long-reach robotic arms. Different manipulator layouts were investigated and an ideal design was selected for a robotic arm that has a 5 [m] reach, 50 [kg] payload, and is intended to operate on large objects with complex curvature. The cross-sectional geometry of the links of the arm were analyzed for optimal stiffness- and strength-to-weight ratios that are capable of preserving high precision and repeatability under time-dependent external excitations. The results lead to a novel multi-segment link design and method of production. A proof-of-concept prototype of a two degrees-of-freedom (2-DOF) robotic arm with a reach of 1.75 [m] was developed. Both static and repeatability testing were performed for verification. The results indicated that the prototype robot main-arm constructed of carbon fiber-epoxy composite material provides good stiffness-to-weight and strength-to-weight ratios. Finite element analysis (FEA) was performed on a 3-D computer model of the arm. Successful verification led to the use of the 3-D model to define the dimensions of an industrial-sized robotic arm. The results obtained indicate high stiffness and minimal deflection while achieving a significant weight reduction when compared to commercial arms of the same size and capability.

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Lao, Zhuo Jin. "Metal oxides as electrode materials for electrochemical capacitors." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060726.101327/index.html.

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Ramabhai, Leena I. "The effect of load carriage on selected metabolic and perceptual responses of military personnel." Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1005189.

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Taking a multi-disciplinary, integrated approach, the present study sought to examine selected physiological and psycho-physical parameters related to load carriage involving a 12 km march under military conditions. Military constraints hampered, but did not entirely inhibit the secondary aim of the study which concerned the effectiveness of relativising loads in order to normalise responses for all soldiers, irrespective of morphological diversity. Forty three subjects were measured in six groups using a test-retest experimental protocol. They were involved in a rest-broken 12 km march at 4 km.h⁻¹ under 40.5 kg absolute total load and under a relative load of 37% of body mass. Heart rates, ratings of perceived exertion (RPE) as well as area and intensity of discomfort were monitored for all subjects. Ten subjects were measured more extensively with regard to physiology using the Metamax, a portable ergospirometry system that provides all the data needed for a complete functional analysis of lung, heart, circulation and metabolic activity. Physiological responses (fc; fb; V̇T; V̇E; V̇O₂; EE; V̇CO₂; R; T°) indicated subjects were not severely physically taxed and that the loads imposed constituted a sub-maximal demand. Moreover, there appeared to be a limited cumulative effect over the 3.5 h. Data from the first and third hours were similar, while the significantly higher responses in the second hour reflected the challenge of the undulating terrain encountered during this section of the march. All responses during the Relative load conditions mirrored those of the Absolute load condition but, because the demands were less, the trends occurred at a reduced level. Furthermore, the reduction in inter-individual variability indicates that relativised load carriage tends to stress the soldiers in a more uniform manner. All "local" RPE responses were higher than "central" ratings, suggesting soldiers were in good cardiovascular condition and experienced marginally more strain in the lower limbs. There was increased perceived strain corresponding to the increase in gradient, with little cumulative effect over the three hours. The shoulders and feet were the two regions in which most discomfort was experienced; the shoulders being the worst area in the first hour and the feet being rated the worst after the third hour of marching. This study clearly demonstrates the probability of a significant improvement in mean combat-readiness following loaded marching by showing that, if loads are set at levels commensurate with individual capabilities to carry them without undue strain, unnecessary physical demands experienced by smaller, more gracile soldiers are reduced.

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Tweedy, Maureen P. "Metabolic Syndrome and Psychosocial Factors." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc11005/.

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Metabolic syndrome is a constellation of risk factors, including abdominal obesity, hypertriglyceridemia, low HDL cholesterol, high blood pressure, and high fasting glucose, that commonly cluster together and can result in cardiovascular disease. The prevalence of metabolic syndrome and the components that comprise the syndrome vary by age and by racial/ethnic group. In addition, previous research has indicated that the risk factors contributing to metabolic syndrome may be exacerbated by exposure to perceived stress. This study utilized data from the 2002, 2004, and 2006 Health and Retirement Study (HRS) and National Health and Nutrition Examination Survey (NHANES) data sets. It was hypothesized that depression and anxiety (conceptualized as stress in this study) increase the risk of presenting with metabolic syndrome while social support decreases the risk of metabolic syndrome. While results of cross-sectional analysis do not indicate a significant relationship between depression and metabolic syndrome (t = -.84, ns), longitudinal analysis does indicate a significant relationship between depression and metabolic syndrome over time (t = -5.20, p <.001). However, anxiety is not significantly related to metabolic syndrome when the relationship is examined through cross-sectional analysis (t = -1.51, ns) and longitudinal analysis (χ² = 13.83, ns). Similarly, social support is not significantly related to metabolic syndrome when examined in cross-sectional (χ² = .63, ns) and longitudinal (t = 1.53, ns) analysis. Although level of stress is not significantly related to metabolic syndrome as a whole, there is a significant relationship between stress and both triglyceride level (t = -2.94, p = .003) and blood glucose level (t = -3.26, p = .001).

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Joshi, Sameehan Shrikant. "Non-Isothermal Laser Treatment of Fe-Si-B Metallic Glass." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062821/.

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Metallic glasses possess attractive properties, such as high strength, good corrosion resistance, and superior soft magnetic performance. They also serve as precursors for synthesizing nanocrystalline materials. In addition, a new class of composites having crystalline phases embedded in amorphous matrix is evolving based on selective crystallization of metallic glasses. Therefore, crystallization of metallic glasses and its effects on properties has been a subject of interest. Previous investigations from our research group related to laser assisted crystallization of Fe-Si-B metallic glass (an excellent soft magnetic material by itself) showed a further improvement in soft magnetic performance. However, a fundamental understanding of crystallization and mechanical performance of laser treated metallic glass was essential from application point of view. In light of this, the current work employed an integrated experimental and computational approach to understand crystallization and its effects on tensile behavior of laser treated Fe-Si-B metallic glass. The time temperature cycles during laser treatments were predicted using a finite element thermal model. Structural changes in laser treated Fe-Si-B metallic glass including crystallization and phase evolution were investigated with the aid of X-ray diffraction, differential scanning calorimetry, resistivity measurements, and transmission electron microscopy. The mechanical behavior was evaluated by uniaxial tensile tests with an InstronTM universal testing machine. Fracture surfaces of the metallic glass were observed using scanning electron microscopy and site specific transmission electron microscopy. Fe-Si-B metallic glass samples treated with lower laser fluence (<0.49 J/mm2) underwent structural relaxation while higher laser flounces led to partial crystallization. The crystallization temperature experienced an upward shift due to rapid heating rates of the order of 104 K/s during laser treatments. The heating cycle was followed by termination of laser upon treatment attainment of peak temperature and rapid cooling of the similar order. Such dynamic effects resulted in premature arrest of the crystallite growth leading to formation of fine crystallites/grain (~32 nm) of α-(Fe,Si) as the major component and Fe2B as the minor component. The structural relaxation, crystallization fractions of 5.6–8.6 Vol% with α-(Fe,Si) as the main component, and crystallite/grain size of the order of 12 nm obtained in laser fluence range of 0.39-0.49 J/mm2 had minimal/no influence on tensile behavior of the laser treated Fe-Si-B metallic glass foils. An increase in laser fluence led to progressive increase in crystallization fractions with considerable amounts of Fe2B (2-6 Vol%) and increase in grain size to ~30 nm. Such a microstructural evolution severely reduced the strength of Fe-Si-B metallic glass. Moreover, there was a transition in fracture surface morphology of laser treated Fe-Si-B metallic glass from vein pattern to chevron pattern. Tensile loading lacked any marked influence on the crystallization behavior of as-cast and structurally relaxed laser-treated metallic glass foils. However, a significant crystallite/grain growth/coarsening of the order of two and half times was observed in the fractured region compared to the region around it for the laser-treated partially crystallized metallic glass foils. The simultaneous effects of stress generation and temperature rise during tensile loading were considered to play a key role in crystallite/grain growth/coarsening.

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17

Ghamarian, Iman. "An Integrated Approach to Determine Phenomenological Equations in Metallic Systems." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc177199/.

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It is highly desirable to be able to make predictions of properties in metallic materials based upon the composition of the material and the microstructure. Unfortunately, the complexity of real, multi-component, multi-phase engineering alloys makes the provision of constituent-based (i.e., composition or microstructure) phenomenological equations extremely difficult. Due to these difficulties, qualitative predictions are frequently used to study the influence of microstructure or composition on the properties. Neural networks were used as a tool to get a quantitative model from a database. However, the developed model is not a phenomenological model. In this study, a new method based upon the integration of three separate modeling approaches, specifically artificial neural networks, genetic algorithms, and monte carlo was proposed. These three methods, when coupled in the manner described in this study, allows for the extraction of phenomenological equations with a concurrent analysis of uncertainty. This approach has been applied to a multi-component, multi-phase microstructure exhibiting phases with varying spatial and morphological distributions. Specifically, this approach has been applied to derive a phenomenological equation for the prediction of yield strength in a+b processed Ti-6-4. The equation is consistent with not only the current dataset but also, where available, the limited information regarding certain parameters such as intrinsic yield strength of pure hexagonal close-packed alpha titanium.

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Shaikh, Nida I. "Serum Vitamin Concentrations are Associated with Metabolic Syndrome and Insulin Resistance in US Children." Digital Archive @ GSU, 2010. http://digitalarchive.gsu.edu/nutrition_theses/20.

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Background: Vitamin D deficiency is a concern in the US. Association between vitamin D status and metabolic syndrome (MetS), insulin resistance (IR), and inflammation is unclear in children. Objective: The relationship between serum vitamin D and MetS, C-reactive protein (CRP), and Homeostatic Model Assessment-IR (HOMA-IR) was investigated. Design: Data from 3 cycles of National Health and Nutrition Examination Survey, 2001-2006 for 3700 (1820, boys; 1880, girls) children and adolescents, aged 12-17 y were used to assess prevalence of vitamin D deficiency (<20 ng>/mL) and association between serum vitamin D and prevalence of MetS, various components of MetS, CRP, and HOMA-IR using multivariate regression models. Results: Overall, prevalences of MetS and vitamin D deficiency were 6.1% and 30.5%, respectively. Prevalence of vitamin D deficiency was higher in girls (52%), blacks (74%), non-supplement users (50%), persons who were examined in winter (56%), and persons in the low poverty income ratio group (57%) compared to their counterparts. Serum vitamin D was inversely associated with waist circumference (P<0.001), systolic blood pressure (P=0.009), and HOMA-IR (P=0.003) and positively associated with HDL-cholesterol (P<0.001). Children with lowest serum vitamin D are at increased risk for MetS (P=0.04; OR 2.26; 95% CI: 1.11, 4.61). Serum vitamin D was not related to CRP (P<0.10). Conclusions: Children with poor vitamin D status are at increased risk for MetS and IR. Because of negative health outcomes associated with MetS and poor vitamin D status when existed individually or in combination, early detection and intervention of these conditions are paramount, especially in children.

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Hufton, Caroline Anne. "Are metabolic diurnal rhythms important during the NOâ†x induced injury of crop plants." Thesis, Lancaster University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334065.

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20

Lee, Stuart M. C. "The elevation of metabolic rate after combined arm-and-leg versus leg-only exercise." Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/40646.

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Previous investigations have shown that metabolic rate remains elevated for a period of time after the cessation of exercise. While other investigations have examined the effect of intensity and duration of prior exercise, the purpose of this study was to examine the effect of exercise mode and the employment of different muscle masses on the elevation of post-exercise metabolic rate (EPOC). Fifteen non-smoking, physically active females (21.1 Â± 1.3 years; 21.4 Â± 4.6 %BF) volunteered for this investigation. Each subject completed a graded maximal exercise test (GXT) on the Monark 880 cycle ergometer (Max HR=192.5 Â± 2.3 bpm; Max V02=2.68 Â± O.lll/min; Max RPE=19.5 Â± 0.1) from which a heart rate corresponding to 70% V02max was chosen. Subjects then exercised on either a Monark 880 cycle ergometer (LE) or the Schwinn Airdyne (ALE) in random order for thirty minutes at the prescribed heart rate (HR). Exercise bouts were separated from each other and from the GXT by at least 48 hours. Workloads were monitored in five minute intervals and adjusted to maintain the appropriate heart rate. The mean exercise heart rates were 172.5 Â± 2.8 bpm for the LE bout and 170.0 Â± 2.8 bpm for the ALE bout, respectively. Two-way repeated measures ANOVA revealed no significant difference \r >0.05) between exercise treatments in terms of HR or V02. Repeated measures trend analYSis revealed no significant difference in either EPOC or post-exercise heart rate between the two treatments across a one-hour seated recovery period. There was also no significant difference (p>O.05) in excess post-exercise caloric expenditure during the recovery period as a result of the different exercise treatments. Therefore, this suggests that neither exercise modality nor the distribution of work over a larger muscle mass had an effect on EPOC when exercise intensity and duration were held constant.

Master of Science

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21

McGlashon, Jacob. "Serotonin neurons maintain central mechanisms regulating metabolic homeostasis and are vital to thermogenic activation." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2121.

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Thermogenic brown and beige adipocytes convert chemical energy to heat by metabolizing glucose and lipids via uncoupling protein 1 (Ucp1), a process known as non-shivering thermogenesis. Serotonin (5-HT) neurons in the ventral medulla are known to regulate sympathetic efferent neurons in the intermediolateral nucleus (IML) necessary to maintain brown adipose tissue (BAT) activity. Previous studies show that mice lacking central 5-HT neurons are incapable of maintaining body temperature in cold, ambient conditions. Due to this direct linkage between 5-HT and thermoregulation, we hypothesized that central 5-HT neurons may be vital to the regulation of brown and beige adipocyte activity. Given that BAT consumes large amounts of substrate when active, we also hypothesized that inactivation of BAT due to deletion of the regulatory neural circuitry (5-HT neurons) would cause metabolic dysregulation. To test this, we generated mice in which the human diphtheria toxin (DT) receptor was selectively expressed in central 5-HT neurons under control of a Pet-1 promoter. Pet-1 is a transcription factor selectively located in mature, central 5-HT neurons. Coincidentally, some cells within pancreatic islets also express Pet-1, and contain adequate machinery to produce, release, and uptake 5-HT. Systemic treatment with DT eliminated 5-HT neurons and caused loss of thermoregulation, BAT steatosis, and a >50% decrease in Ucp1 expression in BAT and beige fat, indicative of reduced thermal production. In parallel, blood glucose increased 3.5-fold, free fatty acids 13.4-fold and triglycerides 6.5-fold. Intracerebroventricular (ICV) treatment with 1/30th the systemic dose of DT induced an even greater thermoregulatory impairment. The metabolic deficits following systemic DT treatment indicate that central 5-HT neurons are essential for proper metabolic regulation. However, such high levels of glucose and lipids also indicate failure of the pancreatic endocrine program following systemic treatment, likely due to moderate destruction of β-cells expressing Pet-1 and the DT receptor. Because ICV treatment caused even greater thermoregulatory and metabolic deficits, where little, if any, of the toxin would spread systemically, central 5-HT neurons are clearly essential for normal central regulation of metabolism. Interestingly, similar BAT and beige fat defects occurred in Lmx1bf/f/p mice, in which 5-HT neurons fail to develop in utero. Assessment of systemically treated animals using a euglycemic/hyperinsulinemic clamp showed extensive fasting hyperglycemia and systemic insulin resistance, coinciding with reduced glucose uptake in skeletal muscle and BAT. The hyperinsulinemic clamp failed to suppress hepatic glucose and fatty acid production, leading to the conclusion that loss of central 5-HT neurons disrupts central hepatic regulation. In attempts to induce BAT thermogenesis and metabolism, we optogenetically stimulated 5-HT neurons in the rostral raphe pallidus and measured BAT and body temperature along with blood glucose. Unfortunately, these stimulations were incapable of increasing BAT temperature and lowering blood glucose, perhaps limiting therapeutic potential of these 5-HT neurons. We conclude that 5-HT neurons are major players in central regulation of metabolic homeostasis, in part through recruitment and activation of brown and beige adipocytes and hepatic substrate production. Data also suggest that 5-HT neurons regulate glucose homeostasis via undefined neural mechanisms independently of BAT activity and pancreatic insulin secretion. Cumulative data on central 5-HT neurons indicate they are master regulators of whole-body metabolism.

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22

Hasenei, Aaron. "Ecophysiology of lionfish metabolic and visual systems: Are there physiological limits to inshore invasion?" Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/496.

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Lionfish (Pterois spp.), an invasive species native to the Indo-Pacific, have permanently established themselves throughout the greater Caribbean, Gulf of Mexico, and regions of the Western Atlantic ranging from as far north as North Carolina to central Brazil. As their fundamental range expands, lionfish threaten to migrate into estuarine environments as they have been found to tolerate low salinities and an eclectic range of temperatures. The physiological capacity of invasion was assessed by quantifying the visual ecology of lionfish utilizing corneal electroretinography (ERG) as well as their metabolic scope and hypoxia tolerances under various temperature-oxygen-regimes utilizing intermittent-flow respirometry. Seasonal changes in temperature-dissolved oxygen levels consistent with Atlantic/Gulf of Mexico inshore estuaries not only exceed the physiological tolerances of lionfish, but also constrain metabolic scope at sub-lethal levels by significantly limiting maximum metabolic rate across all temperatures. Median Scrit values were 33%, 39%, 46%, and 54% at 15, 20, 25, and 30℃ respectively. Luminous sensitivities, temporal resolutions (Flicker fusion frequency), and spectral sensitivities scaled similarly with other estuarine piscivores indicating lionfish possess a visual system that can function effectively within estuarine photic conditions. Overall, visual characteristics of estuaries will not pose as a significant barrier to lionfish, but minimum winter temperatures and hypoxia will pose controlling and limiting factors substantially preventing further inshore invasion. However, caution should still be advised as lionfish may capitalize on specific temporal and spatial scales that provide suitable habitat quality and abundance of prey items. Further insight is needed to forecast the effects of temperature-dissolved oxygen on lionfish metabolic-scope.

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Piuri, G. "METABOLIC SYNDROME, OXIDATIVE STRESS AND LIPOPROTEINS: WHAT ARE THE BIOCHEMICAL EFFECTS OF WEIGHT LOSS?" Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/232643.

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Aim. To examine and compare the composition and the oxidisability of the hydrophobic core and amphipathic surface of lipoproteins in a group of adult males with metabolic syndrome before and after weight loss of at least 5% of their initial weight following a hypocaloric diet. Methods. The concentration of cholesterol, triglycerides, phospholipids, and proteins was studied to analyse the chemical composition of lipoproteins. Pyrenyl-cholesteryl ester and pyrenyl-phosphatidylcholine, incorporated into the hydrophobic core or amphipathic surface of LDL and HDL, respectively, were used for measuring 2,2'-azobis-2-methyl- propanimidamide-dihydrochloride-induced peroxidation kinetics in these regions. Results. In comparison with the initial time, there was an improvement of HDL oxidisability with an increase of lag-time and a reduction of the velocity of propagation of peroxidation in the core of HDL. Parallel but opposite, there was a worsening in the susceptibility to peroxidation of LDL with a reduction in lag-time and an increased propagation rate of peroxidation in the LDL core. After weight loss, LDL showed a higher content of triglycerides whereas HDL showed reduced triglycerides content. In both LDL and HDL, the increase in the percentage of triglycerides was connected with an increased propagation rate of peroxidation kinetic and with a reduction of the lag-time in the hydrophobic core. Conclusions. A more detailed knowledge of the chemical composition and oxidisability of both the surface and core of lipoproteins could be a useful additional means for better understanding the mechanisms that link the changes in lipoproteins metabolism to the risk of cardiovascular disease in patients with metabolic syndrome after weight loss.

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24

Lee, Matthew L., and Jonathan M. Peterson. "Ethanol Disrupts Metabolic Signaling in Liver Cells." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/69.

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Alcohol abuse is the third leading cause of preventable death in the United States. Excessive intake of alcohol can result to alcoholic fatty liver disease, the number one cause of live related mortalities in the US. The outlining purpose for this project is to determine the alcohol-induced changes in the liver cell protein signaling. For this project, we treated H4IIE rat hepatoma cells (with 100 and 200 mM ethanol overnight). H4IIE cells were chosen because they are a commonly used liver cell culture line that maintains characteristics of intact liver cells. After treatment we collected and prepared the cells for protein signaling analysis, using standard western blotting procedure. A western blot detects relative quantity of proteins in a sample. Briefly, protein samples are separated by size through electrophoresis, smaller proteins move faster through the gel so that the larger proteins are toward the top and smaller towards the bottom. The proteins are then transferred to a nitrocellulose membrane and protein concentration is detected by chemiluminescence. We chose to examine the effects of ethanol on the activation of the key regulator of metabolic signaling, Protein Kinase B/Akt (Akt). Based on our results, ethanol has no effect on the total amount of Akt in the H4IIE liver cells. However, ethanol significantly attenuates insulin-induced activation of Akt in a dose-dependent manner, as seen by a reduction in the amount of phosphorylated Akt. Therefore, we conclude that treatments that increase Akt activation may be a viable option for the treatment of alcoholic fatty liver disease.

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Ayyagari, Venkata A. "Surface Degradation Behavior of Bulk Metallic Glasses and High Entropy Alloys." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062863/.

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In this study, the surface degradation behavior was studied for typical examples from bulk metallic glasses (BMGs), metallic glass composites (MGCs) and high entropy alloys (HEAs) alloy systems that are of scientific and commercial interest. The corrosion and wear behavior of two Zr-based bulk metallic glasses, Zr41.2Cu12.5Ni10Ti13.8Be22.5 and Zr57Cu15.4Ni12.6Al10Nb5, were evaluated in as-cast and thermally relaxed states. Significant improvement in corrosion rate, wear behavior, and friction coefficient was seen for both the alloys after thermal relaxation. Fully amorphous structure was retained with thermal relaxation below the glass transition temperature. This improvement in surface properties was explained by annihilation of free volume, the atomic scale defects in amorphous metals resulting from kinetic freezing. Recently developed MGCs, with in situ crystalline ductile phase, demonstrate a combination of mechanical properties and fracture behavior unseen in known structural metals. The composites showed higher wear rates but lower coefficient of friction compared to monolithic amorphous glasses. No tribolayer formation was seen for the composites in sharp contrast to that of the monolithic metallic glasses. Corrosion was evaluated by open circuit potential (OCP) analysis and potentiodynamic polarization. Site-specific corrosion behavior was studied by scanning vibration electrode technique (SVET) to identify formation of galvanic couples. Scanning kelvin probe microscope was used to map elecropositivity difference between the phases and linked to wear/corrosion behavior. Phases with higher elecropositivity were more susceptible to surface degradation. Wear and corrosion synergy in marine environment was evaluated for two high entropy alloys (HEAs), CoCrFeMnNi and Al0.1CoCrFeNi. Between the two alloys, Al0.1CoCrFeNi showed better wear resistance compared to CoCrFeMnNi in dry and marine conditions due to quicker passivation, a higher magnitude of polarization resistance and significantly larger pitting resistance.

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Xu, Fei 1971. "Investigation of Ultratrace Metallic and Organic Contaminants in Semiconductor Processing Environments." Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc277845/.

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Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions and alkaline hydrogen peroxide solution was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the interaction between metallic ions and the silicon-based sensing surface. The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing. The detection of Ag+ content in KODAK waste water was carried out successfully by this novel sensor. Trace levels of organic impurities in the hydrofluoric acid solutions and in the cleanroom air were characterized by multiple internal reflection infrared spectroscopy (MIRIS) using an organics probe prepared directly from a regular silicon wafer.

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Lewallen, Melissa A. "The Metabolic Physiology of Planarian Flatworms." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1538679/.

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Using a high throughput closed respirometry method to measure oxygen consumption, I determined metabolic rates in asexual and sexual Schmidtea mediterranea and Girardia dorotocephala, as a function of temperature, taxon, stressors, reproductive mode, age, regeneration, and specific dynamic action. This study has shown that oxygen consumption can reliably be measured in planaria using optode closed respirometry, and also provided a reliable method for measuring wet mass in planaria, which has been a challenge to researchers in the past. This research revealed that oxygen consumption in S. mediterranea is 1.5-2.1X greater in the sexual strain over the asexual strain at 13-18°C. Within the sexual strain, oxygen consumption is 1.5 -2.2X greater in sexually mature adults over the sexually immature groups (hatchlings, juveniles, and regenerating sexuals). Furthermore, I was able to quantify differences in sexual morphology between these groups exhibiting significant differences in oxygen consumption. The results of this research supports a theory of higher metabolic costs with sexual maturity in S. mediterranea. Therefore, this study has established sexual and asexual S. mediterranea as simple, yet attractive models for investigating energetic costs between sexual and asexual phenotypes. This research also provided quantitative values for specific dynamic action in planaria, with a maximum increase in oxygen consumption of 160% induced by feeding, as well as metabolic relationships in planaria involving temperature, age, and regeneration. These values establish planaria as one of the simplest animal models in which common metabolic patterns, such as SDA and poikilothermic temperature sensitivity, have been demonstrated. Therefore, this research has contributed to the overall knowledge of the basic physiology in this animal, providing the framework for future metabolic studies in planaria involving environmental factors, reproduction, regeneration, development, and aging. Information from this study may supplement interpretation and understanding of modern cellular, molecular, and genomic studies in planaria.

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Warren, David Stephen, and n/a. "The composition and interactions of catalytic surfaces in working environments." University of Otago. Department of Chemistry, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070312.133709.

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In order to clarify the role that water plays in the photocatalytic process, changes in the IR and Raman spectra of P25 TiO₂ thin films were observed upon exposure to liquid water. Further investigation of these spectral changes via dehydration of thin films under nitrogen and oxygen of different humidities led to the observation of spectroscopic features that have been assigned to localised surface phonon modes. When the effect of UV irradiation on these features was investigated, a broad IR absorption due to transitions of electrons in shallow traps was detected under dry nitrogen but not under dry oxygen. Further investigation of the photocatalytic properties of P25 TiO₂ showed a complete removal of a stearic acid film. The final products have been tentatively assigned to a mixture of short chain carbonyl species and adsorbed carbonates as well as carbon dioxide and water. The IR spectrum of the fuel cell membrane material Nafion is complex and literature data varies in some of the assignments. The compound perfluoro(2-ethoxyethane)sulfonic acid was used as a model compound for the Nafion side chain resulting in a clearer assignment of the Nafion IR spectrum. In light of these new assignments changes induced in the region 1100-1300 cm⁻� by variation in humidity and ion exchange have been shown to be mainly the result of changes in the sulfonate asymmetric stretching modes. By flowing a series of solutions containing tetramethylammonium ions and perchlorate ions the surface charge characteristics of a Pt black film were determined in the pH range 2-12. There proved to be a weak positive charge below pH 4 and a weak negative charge above pH 9. Between these points there appeared to be no overall charge on the surface. When perfluoro(2-ethoxyethane)sulfonic acid was adsorbed to a Pt black film changes in its IR spectrum indicated a strong binding via interactions between the sulfonate groups and the Pt surface. The nature of the adsorption of Nafion was less clear cut and, whilst adsorption is strong, it seems possible that hydrophobic interactions between the Nafion backbone and the surface are involved.

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De, Colle Mattia. "Topological Data Analysis to improve the predictive model of an Electric Arc Furnace." Thesis, KTH, Materialvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-201744.

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Data mining, and in particular topological data analysis (TDA), had proven to be successful inabstracting insights from big arrays of data. This thesis utilizes the TDA software AyasdiTM inorder to improve the accuracy of the energy model of an Electric Arc Furnace (EAF), pinpointingthe causes of a wrong calculation of the steel temperature. Almost 50% of the charges analyzedpresented an underestimation of temperature, while under 30% an overestimation.First a dataset was created by filtering the data obtained by the company. After an initialscreening, around 700 charges built the dataset, each one characterized by 104 parameters. Thedataset was subsequently used to create a topological network through the TDA software. Bycomparing the distribution of each parameter with the distribution of the wrong temperatureestimation, it was possible to identify which parameters provided a biased trend. In particular, itwas found that an overestimation of temperature was caused by an underestimation of themelting energy of materials not having through a melting test. It was also found a possible biasedtrend in some distribution of parameters like %O in steel and slag weight, which it is believedare all connected together. Despite not finding a global solution for the reasons behind theunderestimation of temperature, it is believed that a different settings more focused around thematerials used as scrap mix can highlight more on that subject. In conclusion TDA proved itselfefficient as a problem solving technique in the steel industry.

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Setoh, Kazuya. "Three missense variants of metabolic syndrome-related genes are associated with alpha-1 antitrypsin levels." Kyoto University, 2016. http://hdl.handle.net/2433/204579.

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Walters, Jon D. "Microchemical analysis of non-metallic inclusions in C-MN steel shielded metal arc welds by analytical transmission electron microscopy." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA350613.

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Greyling, Johannes Cornelis Arnoldus. "Comparison of the association of PAI-1 act with the metabolic syndrome markers in caucasian and black South African women / Arno Greyling." Thesis, North-West University, 2005. http://hdl.handle.net/10394/1163.

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Motivation: The detrimental effects of obesity and insulin resistance in Caucasians and African-Americans have been the focus of many recent publications, and the association between PAI-1act and markers of the metabolic syndrome is well established but data on African subjects are still lacking. Objectives: To investigate possible differences between the association of PAI-1act with markers of the metabolic syndrome in Caucasian and African women. Methods We used cross-sectional data from the POWIRS I and II studies, involving 95 African and 114 Caucasian women respectively in the Potchefstroom district of the North West Province, South Africa. Results: Mean plasma PAI-1act was significantly higher in the Caucasian than in the African subjects (p < 0.001). Markers for the metabolic syndrome explained 60% of the variance of PAI-1act in the Caucasian group, but only 2.8% of the variance of PAI-1act in the African group. Waist circumference emerged as the strongest independent predictor of PAI-1act in the Caucasian (34%) as well as the African subjects (11%). Conclusion: This study showed clear differences in PAI-1act between African and Caucasian subjects, along with differences in the association of PAI-1act with markers of the metabolic syndrome. Apparent genetic differences between the two groups (especially the role of the 4G/5G genotype) may have an important influence on PAI-1act The role of PAI-1act in the metabolic syndrome may differ between Caucasians and Africans.
Thesis (M.Sc. (Nutrition))--North-West University, Potchefstroom Campus, 2005.

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Sharrock, Jessica. "Female sterile (1) homeotic controls metabolic and immune function and enhances survival via AKT and FOXO." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/female-sterile-1-homeotic-controls-etabolic-and-immune-function-and-nhances-survival-via-akt-and-foxo(13d32527-d51f-42f8-a90a-586bbbf1986d).html.

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The Drosophila melanogaster fat body, analogous to mammalian adipose tissue and the liver, is the primary organ of fat and glycogen storage as well as being responsible for the humoral immune response following infection. Normal functioning of the fat body is of critical importance to the survival of the organism, but many molecular regulators of its function remain ill-defined. Here, for the first time, we demonstrate that the Drosophila bromodomain-containing protein fs(1)h is essential in the fat body for normal lifespan as well as metabolic and immune homeostasis. Under physiological conditions, flies lacking fs(1)h in the fat body exhibit a severely reduced lifespan, abnormally high expression of immune target genes including antimicrobial peptides (AMPs) and cytokines, an inability to utilise triglycerides following periods of starvation, and low basal AKT activity, mostly resulting from systemic defects in insulin signalling. Loss of fs(1)h in the fat body also results in hypoglycemia and a dysregulation of several fat body-derived signals, indicating a role for fat body fs(1)h in the regulation of various systemic endocrine signals. Removing a single copy of the AKT-responsive transcription factor foxo ameliorates almost all the observed phenotypes, restoring lifespan, metabolic function, uninduced immune gene expression, and AKT activity suggesting many of the in vivo effects of fs(1)h in the fat body are foxo-dependent. However, survival is not rescued and AMP expression is still elevated following bacterial infection in fs(1)h knockdown foxo heterozygous flies, indicating some of the phenotypes observed are independent of the FOXO hyperactivation. We propose that the promotion of systemic insulin signalling activity is a key in vivo function of fat body fs(1)h.

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Taylor, John Abner. "Effects of a Surface Engineered Metallic Coating on Elastomeric Valve Stem Seal Leakage." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2690/.

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Valve stem seal leakage is a major source of fugitive emissions, and controlling these emissions can result in added expense in leak detection and repair programs. Elastomeric O-rings can be used as valve stem seals, and O-ring manufacturers recommend lubrication of elastomeric seals to prevent damage and to assure proper sealing. In this research, a metallic coating was applied as a lubricant using a vacuum vapor deposition process to the surface of elastomeric valve stem seals. Valve stem leak measurements were taken to determine if the coated O-rings, alone or with the recommended lubrication, reduced valve stem seal leakage. This research determined that the metallic coating did not reduce valve stem leakage.

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Wos, Melissa Louise, and n/a. "Methods For Understanding Bacterial Metabolic Activity In Activated Sludge." Griffith University. School of Environmental Engineering, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20061031.151641.

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Biological wastewater treatment relies on the diverse and complex metabolic activities of bacteria to remove pollutants. Its success depends on the metabolic efficiency of the bacteria. Activated sludge models use parameters that attempt to depict bacterial growth and metabolic processes. However, current methods do not separate metabolic activity from growth and maintenance. As a result, activated sludge processes are misinterpreted or over-simplified. Alternative methods for gauging bacterial activity have been proposed and include the measurements of cellular derived compounds that relate specifically to energy cycling and include Nicotinamide Adenine Dinucleotide [NADH]. To date, NADH has been largely measured within activated sludge using commercial online fluorimeters with in situ probes. However, this current method provides a measure of the 'bulk' (raw) fluorescence within the system, resulting in difficulties when interpreting fluorescence data and poor sensitivity for detecting changes in intracellular [NADH]. This study has developed a more reliable method for estimating intracellular [NADH] and thus metabolic activity within activated sludge systems. Separating extracellular from intracellular [NADH] in samples was crucial because NADH was released and accumulates in the extracellular environment at a concentration of 200 ~M immediately following bacterial death or lysis. This concentration did not decline overtime. This not only caused high background fluorescence but also reduced the sensitivity of detection for changes in intracellular [NADH]. In particular, considerably higher [NADH] values to those from the extracellular suspensions were obtained following extraction of the intracellular material, suggesting that the cell membranes were not being penetrated by the excitable light source. Of the extraction procedures examined, filtration followed by extraction of the intracellular material with a hot Tris buffer was the most efficient and was recommended for accurate estimates of intracellular [NADH] in situ. In addition, standards were used to quantify NADH (moles per cell and/or unit volume) from unknown samples. The limits of detection were found to be 1.058 - 353 uM, whereas concentrations above 353 jAM self-quenched. Sample concentrations were always within these limits of detection. Hence, the sensitivity, reliability and experimental application of the original method was improved upon and able to be used for the direct measurement of microbial metabolic activity, something that has not been demonstrated before now. This study found that bacteria have between 106~ I 08 NADH molecules per cell depending on their metabolic state. A highly metabolically active bacterial cell had between 1O6~ tO7 NADH molecules, while a less active bacterial cell had between to7 -to8 NADH molecules. These measurements of metabolic activity were simultaneously monitored alongside other measures of bacterial growth, such as the incorporation of radiolabelled thymidine into DNA as a direct measure of DNA replication (new cell synthesis), the incorporation of radiolabelled leucine into protein as a direct measure of protein synthesis, oxygen uptake rates (OUR) as a direct measure of respiration, ATP as a measure of potential energy and dissolved organic carbon (DOC) as a measure of substrate assimilation. As OUR deceased, bacterial growth (using both the thymidine and leucine assays), specific [NADH] and specific [ATP] increased. High OUR and substrate oxidation rates simultaneous with low specific [NADH] indicated high rates of electron transport and thus efficient metabolic activity. Also, low OUR and substrate oxidation rates simultaneous with high specific [NADHI indicated inefficient rates of electron transport, therefore inhibiting oxidative phosphorylation (ATP production). A lack of oxygen as the terminal electron acceptor did not efficiently reoxidise NADH to NAD and resulted in an accumulation of NADH within the cell. Thus, a measure of low specific [NADHI was linked to the efficient rate of reoxidation of NADH to NAD* and reflects high metabolic efficiency. DNA and protein syntheses were coupled following substrate enrichment (glucose or acetate), indicating that bacteria were in balanced growth. However, DNA and protein syntheses became uncoupled once substrate was depleted, indicating unbalanced growth. An average Leu:TdR ratio of 7.4 was determined for activated sludge and was comparable to values published from marine systems. This ratio increased during log growth phase and decreased during stationary growth phases. Specific growth rates determined using the [3HITdR and [3H]Leu assay yielded values ranging from 2 - 10.5 d' and from 2.5 - 6 d1, respectively and were comparable to published values. Changes in OUR, NADH, ATE', DNA replication and protein synthesis were statistically ordinated using multidimensional scaling, and changes (in magnitude and direction) in bacterial metabolic activity were observed. Such methods enable the tracing of where bacteria divert their energies, such as to growth or maintenance and thus provide a greater understanding of bacterial behaviour in activated sludge. While studying anoxic and anaerobic conditions were beyond the scope of this work, the use of such methods to monitor bacterial metabolic activity under such conditions is warranted.

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Holmes, Anna Greer, and not supplied. "Role of interleukin-6 in states of metabolic health and disease." RMIT University. Medical Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070131.121620.

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Obesity and type 2 diabetes are the most prevalent metabolic diseases affecting over 50% of people in the western world. Although the pathogenesis of type 2 diabetes is not fully understood, growing evidence links this disease to a state of chronic inflammation, which occurs in metabolically active tissue such as the liver, adipose tissue and skeletal muscle and results in the secretion of inflammatory cytokines, of which interleukin-6 (IL-6) is one. It is generally accepted that elevations in the plasma and/or tissue of this family of cytokines have a negative effect on whole body glucose homeostasis. While there is compelling evidence for the negative effects of resistin and TNF-á on insulin sensitivity, the role of IL-6 in the etiology of insulin resistance is not fully understood. The notion of negative effects of IL-6 in metabolic processes is further confounded by the marked elevations of IL-6 which occur in conjunction with the beneficial activity of exercise. We firstly sought to examine the effect of the lipolytic hormone adrenaline on IL-6 expression and release in order to establish whether IL-6 acts independently of adrenaline in the regulation of fat metabolism. Reporting the absence of an effect of adrenaline on IL-6, we then investigated the role of IL-6 on metabolic processes in humans at rest and during exercise in circumstances where lipolysis was inhibited. Marked increases in IL-6 circulating protein and tissue gene expression were observed with exercise and further so with fatty acid suppression. In a mouse model of IL-6 depletion marked insulin sensitivity was observed, which was reversed with IL-6 treatment. In a mouse model with normal endogenous IL-6 levels IL-6 treatment also impaired glucose tolerance. Contrastingly, in a rat model both chronic and acute IL-6 treatment improved glucose tolerance In summary, studies from this thesis suggest that, rather than being causally related to insulin resistance, the cytokine IL-6 increases lipolysis, fat oxidation, and glucose metabolism in insulin sensitive tissues in humans. This does not appear to be the case in the mouse, where contrasting actions are observed, perhaps due to differences in the reliance of various parameters for metabolic processes between the species.

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Tsai, I.-Jung. "Perturbations of arachidonic acid metabolism in the metabolic syndrome." University of Western Australia. School of Medicine and Pharmacology, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0065.

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[Truncated abstract] Arachidonic acid is oxidised in vivo by non-enzymatic (free radical) or enzymatic pathways (cyclooxygenase, lipoxygenase, and cytochrome P450) to form a range of biologically active eicosanoids. Specifically, arachidonic acid is metabolised by cytochrome P450 -hydroxylase to produce vasoactive 20-hydroxyeicosatetraenoic acid (20-HETE), and by 5-lipoxygenase to produce proinflammatory leukotriene B4 (LTB4), which can further be metabolised by -hydroxylase to from 20-OH-LTB4 and 20-COOH-LTB4. F2-Isoprostanes (F2-IsoPs) are produced through free radical attack on arachidonic acid and have been recognised as the most reliable markers of lipid peroxidation in vivo. The metabolic syndrome (MetS) is characterised by abdominal obesity, hypertension, insulin resistance, glucose intolerance, and dyslipidemia. It is associated with low-grade inflammation and oxidative stress and an increased risk of developing cardiovascular diseases. Dietary weight loss is strongly recommended for the management of the MetS and can potentially minimise the risk of cardiovascular diseases and diabetes in individuals with the MetS. Little is known regarding the role of these arachidonic acid metabolites in the MetS and the effect of weight loss on their metabolism. Chapter three comprised of three in vitro studies aimed to examine 20-HETE synthesis in human blood cells. 20-HETE acts as a second messenger for vasoconstrictor actions of angiotensin II (Ang II) and endothelin-1 (ET-1) in renal and mesenteric beds. Human neutrophils and platelets are integral to the inflammatory process. ... Production of LTB4 and 20-OH-LTB4 was significantly lower compared with controls (P<0.005) and remained so after adjustment for neutrophil count (P<0.05).The weight loss intervention resulted in a 4.6kg reduction in body weight and a 6.6cm decrease in waist circumference and a significant increase in LTB4 and 20-OH- LTB4 in the weight loss group. Chapter Five continued to investigate the role of other arachidonic acid metabolites, 20-HETE and F2-IsoPs in the MetS and the effect of weight loss. In the case-control study (Human study 1), plasma and urinary 20-HETE and F2-IsoPs were significantly elevated in the MetS group, but no significant difference was found in stimulated-neutrophil 20-HETE. A significant gender x group interaction was observed in that women with the MetS had higher urinary 20-HETE and F2-IsoPs compared to controls (P<0.0001). In a randomised controlled trial (Human study 2), relative to the weight- maintenance group, a 4.6 kg loss in weight resulted in a 2 mmHg fall in blood pressure but did not alter the production of 20-HETE or F2-IsoPs. No significant differences were shown in 20-HETE released from stimulated-neutrophils before and after weight loss. 20-HETE and oxidative stress may be important mediators of cardiovascular disease risk in the MetS. Although a 4% reduction in body weight reduced BP, there were no changes in plasma or urinary 20-HETE or F2-IsoPs. In summary, in vitro studies show that human neutrophils and platelets can produce 20-HETE in response to Ang II and ET-1, and human studies demonstrate that the presence of MetS has a significant impact on arachidonic acid metabolism and effective weight loss can restore leukocyte synthesis of LTB4.

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38

Koch, Rainer, Ulrich Julius, Werner Jaross, and Hans-Egbert Schröder. "Estimation of the Heritability of Latent Variables Which Are Included in a Structural Model for Metabolic Syndrome." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-137470.

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In a study looking for risk factors of atherosclerosis in families with combined hyperlipidemia and hypertension, clinical and biochemical data of 1,149 persons were analyzed to develop two hypothetical multivariate scores concerning the degree to which a patient is affected by the metabolic syndrome. The scores are based on a structural model for low-density cholesterol (LDL) and high-density cholesterol (HDL), triglycerides, uric acid, creatinine, glucose, insulin, systolic blood pressure and waist-to-hip ratio. Age, gender and body mass index were used for adjusting all variables. In segregation analyses of 42 pedigrees without using genotype information, estimations of the heritabilities and environmentally caused variance and covariance components were computed for the individual score values of the two latent factors. The first score shows a heritability of 42%; the environment component disappeared. The score mainly reflects the HDL, LDL and triglyceride levels. The second score shows a heritability of 16% with an environment component of 7%. It includes mainly insulin, uric acid and creatinine. In the search for genetic causes, both scores could be a basis for further phenotypic classification of the metabolic syndrome
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

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39

Koch, Rainer, Ulrich Julius, Werner Jaross, and Hans-Egbert Schröder. "Estimation of the Heritability of Latent Variables Which Are Included in a Structural Model for Metabolic Syndrome." Karger, 2001. https://tud.qucosa.de/id/qucosa%3A27735.

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In a study looking for risk factors of atherosclerosis in families with combined hyperlipidemia and hypertension, clinical and biochemical data of 1,149 persons were analyzed to develop two hypothetical multivariate scores concerning the degree to which a patient is affected by the metabolic syndrome. The scores are based on a structural model for low-density cholesterol (LDL) and high-density cholesterol (HDL), triglycerides, uric acid, creatinine, glucose, insulin, systolic blood pressure and waist-to-hip ratio. Age, gender and body mass index were used for adjusting all variables. In segregation analyses of 42 pedigrees without using genotype information, estimations of the heritabilities and environmentally caused variance and covariance components were computed for the individual score values of the two latent factors. The first score shows a heritability of 42%; the environment component disappeared. The score mainly reflects the HDL, LDL and triglyceride levels. The second score shows a heritability of 16% with an environment component of 7%. It includes mainly insulin, uric acid and creatinine. In the search for genetic causes, both scores could be a basis for further phenotypic classification of the metabolic syndrome.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

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40

Cruz, Matheus Roriz Silva. "Cognitive impairment and frontal-subcortical geriatric syndrome are associated with metabolic syndrome in a stroke-free population." Kyoto University, 2007. http://hdl.handle.net/2433/135709.

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41

Hanna, Kazazian Noël. "Lupus autoimmunity and metabolic parameters are exacerbated in high fat diet-induced obesity due to TLR7 signalling." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0105.

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Les patients atteints de lupus érythémateux systémique ont une augmentation de la prévalence du syndrome métabolique (MetS) mais les mécanismes sous-jacents ne sont pas connus. Le récepteur de type Toll 7 (TLR7), qui reconnait de l’ARN simple brin, joue un rôle important dans la défense anti-microbienne de l’hôte, mais contribue également au développement et à la progression du lupus. Cependant, l’implication de TLR7 dans le MetS est inconnue. L’objectif de mon projet de thèse était d’explorer l’idée nouvelle que la signalisation de TLR7 peut conduire non seulement au lupus mais aussi à des anomalies métaboliques.Nous avons trouvé que l’obésité induite par un régime riche en gras (régime HFD) a conduit à une exacerbation du lupus et de paramètres métaboliques dans des souris TLR8ko, qui développent spontanément une auto-immunité de type lupique à cause d’une augmentation de la signalisation de TLR7 dans les cellules dendritiques (DCs). Au contraire, sous un régime HFD, les souris TLR7/8ko n’ont pas développé de lupus, et les souris TLR7ko et TLR7/8ko ont été protégées contre les anomalies métaboliques incluant l'augmentation de poids et l’intolérance au glucose. De manière intéressante, dans des souris sauvages (WT) le régime HFD a conduit à une augmentation de l’expression de TLR7 et de la production de TNF par les DCs spléniques et hépatiques, et ce phénotype était plus profond dans les souris TLR8ko. Mon étude montre l’implication de la signalisation de TLR7 dans l’interconnexion entre le lupus et les anomalies métaboliques, donc cibler TLR7 pourrait constituer une nouvelle approche comme thérapie contre le lupus et les maladies métaboliques
Systemic lupus erythematosus (SLE) patients have increased prevalence of metabolic syndrome but the underlying mechanisms are unknown. Toll-like receptor 7 (TLR7) that detects single stranded-RNA plays a key role in antimicrobial host defence, but also contributes in the initiation and progression of SLE. However, the implication of TLR7 in MetS is unknown. The objective of my PhD project was to explore the novel idea that TLR7 signalling can lead not only to SLE but also to metabolic abnormalities. We found that high fat diet (HFD)-induced obesity led to exacerbation of lupus and metabolic parameters in TLR8ko mice, which develop spontaneous lupus-like disease due to increased TLR7 signalling by dendritic cells (DCs). In contrast, upon HFD TLR7/8ko mice did not develop SLE, and both TLR7ko and TLR7/8ko mice were protected from metabolic abnormalities including body weight gain and glucose intolerance. Interestingly, in wild-type mice HFD led to an increase of TLR7 expression and TNF production by hepatic and splenic DCs, and this phenotype was more profound in TLR8ko mice. My study uncovers the implication of TLR7 signalling in the interconnection of SLE and metabolic abnormalities, thus targeting TLR7 might be a novel approach as a tailored therapy in SLE and metabolic diseases

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Ahmadian-Najafabadi, Mehdi. "Sintering, microstructure and properties of WC-FeAl-B and WC-Ni3Al-B composite materials." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20061121.154813/index.html.

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43

Weber, Clare L., and n/a. "Metabolic Responses to Supramaximal Exercise and Training: A Gender Comparison." Griffith University. School of Physiotherapy and Exercise Science, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030407.155407.

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The primary aim of this thesis was to investigate the gender-specific responses to supramaximal cycling and to examine the changes in anaerobic and aerobic metabolism that occur in response to high-intensity interval training (HIT). All subjects in the present experiments were untrained, healthy young adults aged between 18 and 35 yr. Cycle ergometry was used for all experimental test procedures and training programs. The accumulated oxygen (AO2) deficit was used to quantify the production of adenosine triphosphate (ATP) via anaerobic metabolism during supramaximal cycling. In addition, pulmonary oxygen uptake measured at the onset of exercise was described using mathematical modeling to determine the rate response of the aerobic energy system during exercise. The purpose of experiment one was to examine the test-retest reliability of the maximal accumulated oxygen deficit (MAOD) measured at 110% and 120% of peak oxygen uptake for cycling in seven untrained male and seven untrained female subjects. After one familiarization trial, all subjects performed two MAOD tests at a power output corresponding to 110% and two tests at 120% of peak oxygen uptake in random order. MAOD was calculated for each subject as the difference between the estimated AO2 demand and the AO2 uptake measured during the exercise bout. The mean±standard error time to exhaustion (TE) for the group was not significantly different between trial one (226±13 s) and trial two (223±14 s) of the 110% test. Likewise, the difference in the TE between trial one (158±11 s) and trial two (159±10 s) was not significant for the 120% test. The intra-class correlation coefficients for the TE were 0.95 for the 110% test and 0.98 for the 120% test. The mean MAOD value obtained in trial one (2.62±0.17 L) was not significantly different from the mean value obtained in trial two (2.54±0.19 L) for the 110% test. Additionally, the mean values for the two trials did not differ significantly for MAOD (2.64±0.21 L for trial one and 2.63±0.19 L for trial two) in the 120% test. The intra-class correlation coefficients for MAOD were 0.95 for the 110% test and 0.97 for the 120% test. All intra-class correlation coefficients were significant at p < 0.001. When conducted under standardized conditions, the determination of MAOD for cycling was highly repeatable at both 110% and 120% of peak oxygen uptake in untrained male and female subjects. The results observed in experiment one suggest that the MAOD may be used to compare the anaerobic capacity (AC) of men and women and to examine changes in the contribution of the anaerobic energy systems before and after training. Experiment two examined the gender-specific differences in MAOD before and after 4 and 8 wk of HIT. Untrained men (n=7) and women (n=7) cycled at 120% of pre-training peak oxygen uptake to exhaustion (MAOD test) pre-, mid-, and post-training. A post-training timed test was also completed at the MAOD test power output, but this test was stopped at the TE achieved during the pre-training MAOD test. The 14.3±5.2% increase in MAOD observed in males after 4 wk of training was not different from the 14.0±3.0% increase seen in females (p > 0.05). MAOD increased by a further 6.6±1.9% in males and this change was not different from the additional 5.1±2.3% increase observed in females after the final 4 wk of training. Peak oxygen uptake measured during incremental cycling increased significantly (p < 0.01) in male but not in female subjects after 8 wk of training. Moreover, the AO2 uptake was higher in men during the post-training timed test compared to the pre-training MAOD test (p < 0.01). In contrast, the AO2 uptake was unchanged from pre- to post-training in female subjects. The increase in MAOD with training was not different between men and women suggesting an enhanced ability to produce ATP anaerobically in both groups. However, the increase in peak oxygen uptake and AO2 uptake obtained in male subjects following training indicates improved oxidative metabolism in men but not in women. It was concluded that there are basic gender differences that may predispose males and females to specific metabolic adaptations following an 8-wk period of HIT. Increases in AO2 uptake during supramaximal cycling demonstrated in men after training led to the hypothesis that peak oxygen uptake kinetics are speeded in male subjects with short-term HIT. It was suggested that training does not improve peak oxygen uptake kinetics in women as no change in AO2 uptake was found after 8 wk of HIT in female subjects. The purpose of experiment three was to examine peak oxygen uptake kinetics before and after 8 wk of HIT in six men and six women during cycling at 50% (50% test) and 110% (110% test) of pre-training peak oxygen uptake. A single-term exponential equation was used to model the peak oxygen uptake response (after phase I) during the 50% and 110% tests pre- and post-training. In addition, phase II and III of the peak oxygen uptake response during the 110% tests were examined using a two-term equation. The end of the phase I peak oxygen uptake response was identified visually and omitted from the modeling process. The duration of phase I determined during all experimental tests was not different between men and women and did not change with training in either group. Before training, men obtained a phase II peak oxygen uptake time constant (t2) of 29.0±3.3 s during the 50% test which was not different to the t2 of 28.8±2.2 s attained by women. In addition, the t2 determined during the 50% test was unchanged after 8 wk of HIT in both groups. The peak oxygen uptake kinetics examined during the 110% tests before training were well described by a single-term model in all male and female subjects. The t2 determined before training for the 110% test was significantly faster in men than in women. Furthermore, peak oxygen uptake was unchanged in female subjects and the t2 remained unaltered with 8 wk HIT (pre 45.5±2.2; post 44.8±2.3 s). In contrast, male subjects achieved a significantly higher peak oxygen uptake after training and the t2 determined for men during the 110% test was faster after training (36.4±1.6 s) than before training (40.1± 1.9 s). Improved model fits were obtained with the two-term equation compared to the single-term equation in two of the six male subjects during the 110% test post-training. It was found that the onset of the peak oxygen uptake slow component occurred at a mean time of 63.5±2.5 s and the t2 was reduced to 18.4±1.7 s. Using a Wilcoxon Signed Ranks z-test, the t2 described by the single-term equation in the remaining four subjects was determined to be significantly faster after training than before training, thus confirming the results obtained from the original group (n=6) of male subjects. End exercise heart rate (HREE) values obtained during the 50% and 110% tests were not different between men and women. During the 50% test, HREE values were unchanged, whereas HREE was significantly decreased during the 110% test after training in both groups. These data show that HIT might improve oxidative metabolism in men but not in women as reflected by a greater peak oxygen uptake and faster peak oxygen uptake kinetics during supramaximal work rates. We further suggest that the faster peak oxygen uptake kinetics demonstrated in men after training are probably not due to an improvement in cardiac function. Finally, the augmentation of oxidative metabolism during exercise after HIT in men might be dependent on the intensity of the exercise bout at which the peak oxygen uptake response is examined. The findings presented in this thesis suggest that MAOD is a reliable measure in both male and female subjects and can be used to monitor changes in anaerobic ATP production during supramaximal cycling. Moreover, these data suggest that 4 and 8 wk of HIT produce similar changes in anaerobic ATP generation in men and women. Finally, 8 wk of HIT results in the increase of peak oxygen uptake and AO2 uptake as well as the speeding of peak oxygen uptake kinetics during supramaximal cycling in male subjects. There was no evidence to suggest that oxidative metabolism was improved in women after short-term HIT. In conclusion, improvement in supramaximal exercise performances should be examined specifically for changes in the anaerobic and aerobic contributions to energy production. In addition, it is suggested that gender should be of primary consideration when designing exercise-training programs where improvement in both anaerobic and aerobic metabolism is required.

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Choudhury, Feroza Kaneez. "Rapid Metabolic Response of Plants Exposed to Light Stress." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157543/.

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Environmental stress conditions can drastically affect plant growth and productivity. In contrast to soil moisture or salinity that can gradually change over a period of days or weeks, changes in light intensity or temperature can occur very rapidly, sometimes over the course of minutes or seconds. So, in our study we have taken an metabolomics approach to identify the rapid response of plants to light stress. In the first part we have focused on the ultrafast (0-90 sec) metabolic response of local tissues to light stress and in the second part we analyzed the metabolic response associated with rapid systemic signaling (0-12 min). Analysis of the rapid response of Arabidopsis to light stress has revealed 111 metabolites that significantly alter in their level during the first 90 sec of light stress exposure. We further show that the levels of free and total glutathione accumulate rapidly during light stress in Arabidopsis and that the accumulation of total glutathione during light stress is dependent on an increase in nitric oxide (NO) levels. We further suggest that the increase in precursors for glutathione biosynthesis could be linked to alterations in photorespiration, and that phosphoenolpyruvate could represent a major energy and carbon source for rapid metabolic responses. Taken together, our analysis could be used as an initial road map for the identification of different pathways that could be used to augment the rapid response of plants to abiotic stress. In addition, it highlights the important role of glutathione in initial stage of light stress response. Light-induced rapid systemic signaling and systemic acquired acclimation (SAA) are thought to play an important role in the response of plants to different abiotic stresses. Although molecular and metabolic responses to light stress have been extensively studied in local leaves, and to a lesser degree in systemic leaves, very little is known about the metabolic responses that occur in the different tissues that connect the local to the systemic leaves. These could be important in defining the specificity of the systemic response as well as in supporting the propagation of different systemic signals, such as the reactive oxygen species (ROS) wave. Here we report that local application of light stress to one rosette leaf resulted in a metabolic response that encompassed local, systemic and transport tissues (tissues that connect the local and systemic tissues), demonstrating a high degree of physical and metabolic continuity between different tissues throughout the plant. We further show that the response of many of the systemically altered metabolites could be associated with the function of the ROS wave, and that the level of eight different metabolites is altered in a similar way in all tissues tested (local, systemic, and transport tissues). These compounds could define a core metabolic signature for light stress that propagates from the local to the systemic leaves. Taken together, our findings suggest that metabolic changes occurring in cells that connect the local and systemic tissues could play an important role in mediating rapid systemic signaling and systemic acquired acclimation to light stress.

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Adhikari, Pashupati Raj. "Knowledge Based System and Decision Making Methodologies in Materials Selection for Aircraft Cabin Metallic Structures." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862774/.

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Materials selection processes have been the most important aspects in product design and development. Knowledge-based system (KBS) and some of the methodologies used in the materials selection for the design of aircraft cabin metallic structures are discussed. Overall aircraft weight reduction means substantially less fuel consumption. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures inside the cabin. Among various methodologies of materials selection using Multi Criterion Decision Making (MCDM) techniques, a few of them are demonstrated with examples and the results are compared with those obtained using Ashby's approach in materials selection. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes in the process. Aluminum alloys with high strength-to-weight ratio have been second-to-none in most of the aircraft parts manufacturing. Magnesium alloys that are much lighter in weight as alternatives to the Al-alloys currently in use in the structures are tested using the methodologies and ranked results are compared. Each material attribute considered in the design are categorized as benefit and non-benefit attribute. Using Ashby's approach, material indices that are required to be maximized for an optimum performance are determined, and materials are ranked based on the average of consolidated indices ranking. Ranking results are compared for any disparity among the methodologies.

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46

Repchuk, Yu V. "The association of hormonal and metabolic parameters and the AGT gene polymorphism (rs699) in patients with essential hypertension." Thesis, БДМУ, 2022. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/19577.

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47

Bowman, G. R. "Studies of titanium (IV) complexes of mixed nitrogen and oxygen donor macrocycles and related Schiff base ligands /." View thesis, 2002. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030721.114851/index.html.

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Lahiri, Ipsita. "Metabolic Engineering in Plants to Control Source/sink Relationship and Biomass Distribution." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc283836/.

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Traditional methods like pruning and breeding have historically been used in crop production to divert photoassimilates to harvested organs, but molecular biotechnology is now poised to significantly increase yield by manipulating resource partitioning. It was hypothesized that metabolic engineering in targeted sink tissues can favor resource partitioning to increase harvest. Raffinose Family Oligosaccharides (RFOs) are naturally occurring oligosaccharides that are widespread in plants and are responsible for carbon transport, storage and protection against cold and drought stress. Transgenic plants (GRS47, GRS63) were engineered to generate and transport more RFOs through the phloem than the wild type plants. The transgenic lines produced more RFOs and the RFOs were also detected in their phloem exudates. But the 14CO2 labeling and subsequent thin layer chromatography analysis showed that the RFOs were most likely sequestered in an inactive pool and accumulate over time. Crossing GRS47 and GRS63 lines with MIPS1 plants (that produces more myo-inositol, a substrate in the RFO biosynthetic pathway) did not significantly increase the RFOs in the crossed lines. For future manipulation of RFO degradation in sink organs, the roles of the endogenous α-galactosidases were analyzed. The alkaline α-galactosidases (AtSIP1 and AtSIP2 in Arabidopsis) are most likely responsible for digesting RFOs in the cytoplasm and may influence the ability to manipulate RFO levels in engineered plants. Atsip1/2 (AtSIP1/AtSIP2 double-knockout plants) were generated and phenotypically characterized based on seed germination patterns, flowering time, and sugar content to observe the impact on RFO sugar levels. The observations and analysis from these lines provide a basis for further insight in the manipulation of resource allocation between source and sink tissues in plants for future research.

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49

Aguilar, Ayala Roberto. "Applications of Metallic Clusters and Nanoparticles via Soft Landing Ion Mobility, from Reduced to Ambient Pressures." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248434/.

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Nanoparticles, simple yet groundbreaking objects have led to the discovery of invaluable information due to their physiological, chemical, and physical properties, have become a hot topic in various fields of study including but not limited to chemistry, biology, and physics. In the work presented here, demonstrations of various applications of chemical free nanoparticles are explored, from the determination of a non-invasive method for the study of the exposome via using soft-landing ion mobility (SLIM) deposited nanoparticles as a matrix-assisted laser desorption/ionization (MALDI-MS) matrix replacement, to the direct SLIM-exposure of nanoparticles onto living organisms. While there is plenty of published work in soft-landing at operating pressures of 1 Torr, the work presented here shows how this technology can be operated at the less common ambient pressure. The ease of construction of this instrument allows for various modifications to be performed for a wide array of applications, furthermore the flexibility in metallic sample, operating pressure, and deposition time only open doors to many other future applications. The work presented will also show that our ambient SLIM system is also able to be operated for toxicological studies, as the operation at ambient pressure opens the door to new applications where vacuum conditions are not desired.

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Ho, Yee Hsien. "In Vitro Behavior of AZ31B Mg-Hydroxyapatite Metallic Matrix Composite Surface Fabricated via Friction Stir Processing." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862762/.

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Magnesium and its alloys have been considered for load-bearing implant materials due to their similar mechanical properties to the natural bone, excellent biocompatibility, good bioactivity, and biodegradation. Nevertheless, the uncontrollable corrosion rate in biological environment restrains their application. Hydroxyapatite (HA, Ca10(PO4)6(OH)2) is a widely used bio-ceramic which has bone-like mineral structure for bone fixation. Poor fracture toughness of HA makes it not suitable for load-bearing application as a bulk. Thus, HA is introduced into metallic surface in various forms for improving biocompatibility. Recently friction stir processing (FSP) has emerged as a surface modification tool for surface/substrate grain refinement and homogenization of microstructure in biomaterial. In the pressent efforts, Mg-nHA composite surface on with 5-20 wt% HA on Mg substrate were fabricated by FSP for biodegradation and bioactivity study. The results of electrochemical measurement indicated that lower amount (~5% wt%) of Ca in Mg matrix can enhance surface localized corrosion resistance. The effects of microstructure,the presence of HA particle and Mg-Ca intermetallic phase precipitates on in vitro behavior of Mg alloy were investigated by TEM, SEM, EDX,XRD ,and XPS. The detailed observations will be discussed during presentation.

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Dissertations / Theses on the topic 'Metalic Art'

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