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1
Addy, S. W. "Radiation induced degradation of elastomers." Thesis, Sheffield Hallam University, 1987. http://shura.shu.ac.uk/19200/.
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An attempt has been made to evaluate the kinetics of the thermal and combined thermal/radiative degradation of a peroxide cured polydimethylsiloxane elastomer (PDMS), and a vinylidene fluoride-hexafluoropropylene elastomer (Viton E60-C),by chemical stress relaxation measurements. It was observed that the PDMS elastomer degraded thermally by hydrolytic scission of the main chain and chain reformation by condensation of the silanol chain end groups. However,predominant chain reformation was observed during thermal degradation studies and it was believed that this was a consequence of the reformation of chains cut during the test,and also the reformation of chains cut prior to the test in the post cure operation. These two components of the observed chain reformation response were subsequently rationalized by a model. Thermal degradation of the Viton E60-C elastomer appeared to take place by hydrolytic scission of the amine crosslinkages, and subsequent crosslink reformation by condensation,indicating that the material had not been subjected to a suitable post cure treatment in order to remove water generated by the vulcanization reaction. At temperatures above 200°C predominant crosslinking was observed and this was attributed to the presence of a concurrent reaction which leads to the formation of ring structures. Thermal/radiative degradation studies indicated that temperature and radiation had a synergistic effect on the overall rate of induced chain scission in the PDMS elastomer but the mechanisms responsible for this phenomenon have yet to be established.
2
Zupac, Dragan. "Radiation-induced mobility degradation in DMOS transistors." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186456.
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Effects of radiation-induced interface-trapped charge and oxide-trapped charge on the inversion-layer carrier mobility in double-diffused metal-oxide-semiconductor (DMOS) power transistors are investigated. Interface-trapped charge is more effective in scattering inversion-layer carriers than oxide-trapped charge. However, the effects of oxide-trapped charge must be taken into account in order to properly describe the mobility behavior. An effective approach to detecting effects of oxide-trapped charge and separating these effects from effects of interface-trapped charge is demonstrated. Detection is based on analyzing mobility data sets which have different functional relationships between the two trapped charge components. These relationships may be linear or nonlinear. Separation of effects of oxide-trapped charge and interface-trapped charge is possible only if these two trapped charge components are not linearly dependent. A significant contribution of oxide-trapped charge to mobility degradation is demonstrated and quantified. Effects of oxide-trapped charge may be dominant in non-hardened DMOS transistors irradiated at relatively high dose rates. In addition, DMOS devices have been irradiated at room temperature and mobility measurements performed at room temperature and at 77 K to analyze mobility degradation due to the same density of radiation-induced defects at these two different temperatures. Radiation-induced mobility degradation is more pronounced at 77 K than at room temperature, due to increased relative importance of Coulomb scattering from trapped charge when phonon scattering is significantly reduced. Effects of oxide-trapped charge on mobility are more pronounced at cryogenic temperatures than at room temperature.
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Andersson, Robin. "Modeling Radiation Induced Degradation of Lattice Thermal Conductivity." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277885.
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Nuclear power technology is currently experiencing a revolutionary development process and its utilization is researched and debated throughout the world whereas sustainability is one of the most important topics in the material science arena. Some components in a nuclear power plant are subject to an irradiating environment which will cause significant damage to the material over time. Thus, it is of utmost importance that the affected materials are well designed for enduring such conditions because of the extensive lifetime of a nuclear power plant. The highly energetic particles that are inherent with nuclear reactions will generate point defects in the microstructure of the material which will alter its macroscopic behavior. Managing heat is crucial in a nuclear power plant and therefore this thesis is devoted to modeling the degradation effect on the lattice thermal conductivity as a result of the point defects, and to establish the intervening relation. This is achieved by ab initio simulations on supercells where the quantum-mechanical forces are calculated with density functional theory and with the generalized gradient approximation for the exchange-correlation term. The phonon Boltz- mann equation is solved by linearization and by using the relaxation-time ap- proximation which allows the lattice thermal conductivity to be calculated for the model. The phonon band modes and the phonon density of states is examined as well. To date there are no reports currently found in the literature where this topicis approached with similar methods.Kärnkraftsteknologin genomgår just nu en revolutionerande utvecklingspro- cess och dess användning debatteras över hela världen där hållbarhet är en av de viktigaste ståndpunkterna i materialvetenskapsområdet. Vissa komponenter i ett kärnkraftverk blir utsatta för en bestrålande miljö vilket orsakat stor skada på materialet över tid. Det är därför av högsta vikt att dessa material är desig- nade för att motstå sådana miljöer på grund av kärnkraftverkens långa livstid. De högenergetiska partiklarna som är förekommande vid kärnreaktioner gene- rerar punktdefekter i materialets mikrostruktur vilka ändrar de makroskopiska egenskaperna hos materialet. Värmehantering är kritiskt i ett kärnkraftverk och därför är detta arbete de- dikerat till att modellera effekten av försämring av värmeledningsförmågan i kristallgittret, som resultat av punktdefekterna, och att definiera sambandet. Detta uträttas genom ab initio simuleringar av superceller där de kvantmekaniska krafterna beräknas med täthetsfunktionalsteori med en generaliserad approximation av täthetsgradienten för den tillhörande utbytes- och korrela- tionstermen. Boltzmann ekvationen löses med hjälp av linjärisering och med en approximation av relaxationstiden vilket används för att beräkna värmeledningen i gittret för modellen. Fononernas band-moder och tillståndstäthet undersöks därtill. För närvarande finns det inga rapporter bland litteraturen där detta ämne behandlas med samma metoder.
4
Mohammadian, Mehrdad. "Environmental degradation of poly(ethyleneterephthalate)." Thesis, Manchester Metropolitan University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317574.
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The degradation of amorphous and orientated PET is investigated by several analytical methods. In this study, samples of both amorphous and orientated PET material were exposed to wet and dry soil, various humidities and temperature as well as UV irradiation. Results of accelerated ageing studies indicate that the amorphous sheet and biaxially orientated bottles degrade mainly due to de-esterification and oxidative chain scission due to their low crystallinity. At high temperatures (70-90) breakdown, as characterisedb y viscosity and chain scission measurements,is indicative of significant polymer deterioration. Breakdown is enhanced by increasing temperature, increasing relative humidity and UV irradiation. In this regard the polyester bottles are more stable than sheet due to a greater degree of orientation and hence higher degree of crystallinity. However, the rate of degradation is also a function of the surrounding environment. During the course of degradation, an increase in crystallinity was observed for both sheet and bottles. The rate of increase in crystallinity is initially rapid and is associated with plasticization by moisture and subsequent annealing. The dry conditions and UV irradiation cause negligible increase in crystallinity . An increase in the number of end groups was observed which is due to chain scission. Whilst the carboxyl and hydroxyl end groups were increased at the same rate asthermally degraded samples, the increase of carboxyl end groups for UV degraded samples was significantly higher than hydroxyl end groups. This increase is initially sharp and then more gradual with almost the same rate as hydroxyl end groups. A higher level of carboxyl end groups is due to the release of carbon dioxide and carbon monoxide mainly on the surface of the polymer. In this work two methods were used to introduce stability to the polymer. The first was preconditioning the polymer in an inert atmosphere for 48 hours at 600C which had a better effect for bottles This stabilizing effect was observed for both thermal degradation and UV irradiation of polyester materials. The second method was stabilizing polyester against UV irradiation by the incorporation of naphthalenea nd benzophenoned erivatives to the structure of the polyester. In this case the dihydroxybenzophenone showed the greatest stabilizing effect. Hydroperoxide formation during hydrolytic degradation is found to be both temperature and humidity dependent and appears to play a secondary role in thermal oxidation.
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Barbara, Nabil Victor 1964. "Simulation of radiation-induced parametric degradation in electronic amplifiers." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277143.
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Many high performance amplifiers use power MOSFETs in their output stages, especially in operational amplifier applications whenever high current or power is needed. MOSFETs have advantages over bipolar transistors in amplifier output stage because MOSFETs are majority carrier devices. The result is wide frequency response, fast switching and better linearity than power bipolar transistors. But unlike bipolar circuits, which are relatively tolerant of ionizing radiation, MOSFETs may suffer severe parametric degradation at low total-dose levels. The effects of ionizing radiation on MOSFETs are discussed, and the performance of an amplifier circuit that uses a complementary MOSFET source follower in its output stage is simulated to examine the effect of MOSFET radiation damage on amplifier performance. An increase in power dissipation was the most significant degradation caused by ionizing radiation.
6
Tan, Chuting Tan. "Radiation-Induced Material and Performance Degradation of Electrochemical Systems." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu151448116966595.
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Bennet, Francesca Chemical Sciences & Engineering Faculty of Engineering UNSW. "Studying polymer degradation at a molecular level via soft ionisation mass spectrometry." Publisher:University of New South Wales, 2009. http://handle.unsw.edu.au/1959.4/43692.
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The present study employs a range of soft-ionisation mass spectrometry techniques to study the degradation of model compounds of poly(methyl methacrylate), poly(n-butyl acrylate) and poly(2-hydroxyethyl methacrylate) under conditions designed to simulate the worst-case scenario that would be experienced by a polymer used in a surface coating on a steel roof. Vinyl-terminated and saturated polymers were degraded for periods of up to 2 years under simulated solar radiation at a temperature of 95??C, temperature of 95 ??C in the dark, and simulated solar radiation at 35??C. Similar degradation mechanisms were observed under heat and UV radiation. The presence of UV radiation accelerated the degradation occurring at high temperature, and vice versa. The combination of heat and UV radiation is far more detrimental to the polymers than either of these conditions alone. Both vinyl-terminated and saturated pMMA degraded under UV radiation at 95??C, whereas under conditions of UV radiation alone or high temperature alone, the saturated polymer was found to be stable. The vinyl-terminated pMMA degrades in all cases via the formation of ethylene oXide-type end groups, which subsequently rearrange under the expulsion of formaldehyde and 2-oxo-propionic acid methyl ester. This is in contrast to all previous literature, in which pMMA degrades via depolymerisation and is stable at 95??C. Degradation of pBA included a degradation mechanism similar to that of pMMA in addition to other polymer fragments, some of which cannot be assigned. pBA (both saturated and vinyl-terminated) showed a tendency to crosslink under all degradation conditions in this study. Only saturated pHEMA was stable under thermal degradation. In all other cases, pHEMA showed some degradation, but displayed a much greater tendency to crosslink rapidly. Terminal vinyl bonds were shown in all cases to be a weak point in the polymer with respect to degradation. pMMA was found to be the least reactive of these polymers. pHEMA showed some small degradation but had a greater tendency to crosslink via the hydroxyethyl side groups. pBA does not have any such reactive groups, and its crosslinking reaction may be explained via the acrylate backbone, or the longer alkyl ester group.
8
Gold, Don William. "High energy electron radiation degradation of gallium arsenide solar cells." Thesis, Monterey, California: U.S. Naval Postgraduate School, 1986. http://hdl.handle.net/10945/21891.
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Thurstan, Sarah Ashley. "Acellular mechanisms of extracellular matrix degradation." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/acellular-mechanisms-of-extracellular-matrix-degradation(7fae308d-8e54-4da6-9c27-4da89ec55ab1).html.
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Exposure of the skin to ultraviolet radiation (UVR) results clinically in the formation of deep wrinkles and mottled pigmentation and histologically, in a vast remodelling of the dermal extracellular matrix (ECM), in particular the elastic fibre network. Fibrillin microfibrils and fibulin-5 are early biomarkers of photoageing, where a loss of these fibres from the dermal epidermal junction is apparent. A study by our group showed that isolated fibrillin microfibrils and fibronectin which are rich in amino acids which absorb energy from UVR (UV-chromophores) are susceptible to UVR-induced damage, whilst UV-chromophore poor collagen type I is not. This research, with other earlier studies, indicates that acellular mechanism may work in tandem with cell-mediated up-regulation of matrix metalloproteinases (MMPs) in the progression of photoageing. This thesis aims to: i) test whether acellular mechanisms of photoageing are a result of direct photon absorption and/or the photodynamic production of reactive oxygen species (ROS); ii) assess the functional consequences of UVB degradation on the susceptibility of fibrillin microfibrils to MMPs and; iii) assay whether ECM proteins are differentially susceptible to solar simulated radiation (SSR) or UVA (315-400nm) alone using physiologically relevant doses of irradiation. Isolated proteins were exposed to UVB (280-315nm) in depleted-O2 conditions and in the presence of deuterium oxide. Depleted-O2 conditions decreased and deuterium oxide conditions increased UVR-induced degradation. Isolated proteins also show a similar pattern of degradation when exposed to H2O2 as an exogenous source of ROS. These results indicate that ROS play an important role in the differential degradation of dermal proteins. MMPs-3 and -9 are both upregulated in the skin after exposure to UVR and have the ability to degrade elastic fibre components. After exposure to UVB, damaged fibrillin microfibrils become more susceptible to degradation by both MMPs-3 and -9. Chromophore-rich fibrillin microfibrils and fibronectin are susceptible to degradation by both SSR and UVA alone, whereas chromophore-poor collagens type I and VI and tropoelastin are not. These results support our previous findings that amino acid composition of proteins is a good indicator of their relative susceptibility to UV-induced damage with a physiologically relevant irradiation system. In conclusion this work shows that ROS are an important mediator of acellular mechanisms of photoageing and that amino acid composition is a good indication of relative susceptibility of proteins to both ROS and UVR. The ability to predict ROS-susceptible proteins also has wider implications for human ageing as a whole.
10
Pattenden, Caroline Sarah. "The effect of radiation on the thermal stability of polyisobutylene." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366649.
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Stuart, Scott. "Ionizing radiation induces ATM-independent degradation of p21Cip1 in transformed cells." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3336826.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed Jan. 6, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Knight, P. A. "Nucleation and development of radiation damage in ceramics." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258166.
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Witczak, Steven Christopher 1962. "Current gain degradation in bipolar junction transistors due to radiation, electrical and mechanical stresses." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282140.
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The current gain of bipolar junction transistors is reduced due to ionizing radiation exposure or hot-carrier stressing. Radiation-induced degradation is particularly severe at the low dose rates encountered in space. In this work, the dose rate effect in lateral and substrate pnp bipolar transistors is rigorously quantified over the range of 0.001 to 294 rad(Si)/s. Gain degradation shows little dependence on dose rate below 0.005 rad(Si)/s, suggesting that degradation enhancement comparable to that expected from space-like dose rates was achieved. In addition, the effect of ambient temperature on radiation-induced gain degradation at 294 rad(Si)/s is thoroughly investigated over the range of 25 to 240°C. Degradation is enhanced with increasing temperature while simultaneously being moderated by in situ annealing such that, for a given total dose, an optimum irradiation temperature for maximum degradation results. Optimum irradiation temperature decreases logarithmically with total dose and is larger and more sensitive to dose in the substrate device than in the lateral device. Maximum high dose rate degradation at elevated temperature closely approaches low dose rate degradation in both of the devices. A flexible hardness assurance methodology based on accelerated irradiations at elevated temperatures is described. The influence of mechanical stress on the radiation hardness of single-crystalline emitter transistors is investigated using x-ray diffraction. Correlation of device radiation sensitivity and mechanical stress in the base supports previously reported observations that Si-SiO₂ interfaces exhibit increased susceptibility to radiation damage under tensile Si stress. Relaxation of processing-induced stress in the base oxide due to ionizing radiation is smaller than the stress induced by emitter contact metallization followed by a post-metallization anneal. Possible mechanisms for radiation-induced stress relaxation and their effect on the radiation sensitivity of bipolar transistors are discussed. The combined effects of ionizing radiation and hot-carrier stress on the current gain of npn transistors are investigated. The hot-carrier response of the transistors is improved by radiation damage, whereas hot-carrier damage has little effect on subsequent radiation stress. Characterization of the temporal progression of hot-carrier effects reveals that hot-carrier stress acts initially to reduce excess base current and improve current gain in irradiated transistors. Numerical simulations show that the magnitude of the peak electric-field within the emitter-base depletion region is reduced significantly by net positive oxide charges induced by radiation. The interaction of the two stress types is explained in a physical model based on the probability of hot-carrier injection and the neutralization and compensation of radiation damage in the base oxide. The results of this work further the understanding of stress-induced gain degradation in bipolar transistors and provide important insight for the use of bipolar transistors in stress environments.
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Coleman, Heather Margaret. "Photocatalysis of oestrogens in water." Thesis, University of Ulster, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342532.
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Kosier, Steven Louie. "Modeling gain degradation in bipolar junction transistors due to ionizing radiation and hot-carrier stressing." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186751.
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The roles of net positive oxide trapped charge and surface recombination velocity in producing excess base current in bipolar junction transistors (BJTs) are identified. Although the interaction of these two quantities is physically complex, simple approaches for estimating their magnitude from measured BJT characteristics are presented. The oxide charge is estimated using a transition voltage in the plot of excess base current versus emitter bias. Two approaches for quantifying the effects of surface recombination velocity are described. The first measures surface recombination directly using a gated diode, while the second estimates its effects using an intercept current that is easily obtained from the BJT itself. The results are compared to two-dimensional simulations and measurements made on test structures. The techniques are simple to implement and provide insight into the mechanisms and magnitudes of the radiation-induced damage in BJTs. A physically-based comparison between hot-carrier and ionizing radiation stress in BJTs is presented as well. Although both types of stress lead to qualitatively similar changes in the current gain of the device, the physical mechanisms responsible for the degradation are quite different. Implications for correlating and comparing hot-carrier-induced and ionizing-radiation-induced damage are discussed. Finally, the worst-case increase in base current is shown to be dose-rate independent. This fact allows the worst-case response of bipolar devices to be determined using convenient laboratory dose rates.
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OLIVEIRA, ANA C. F. de. "Estudo dos efeitos da radiação gama no polietileno linear de baixa densidade (PELBD) injetado." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11803.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2014-11-10T11:49:28Z
No. of bitstreams: 0Made available in DSpace on 2014-11-10T11:49:28Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Kassel, Florian Robert [Verfasser], and W. de [Akademischer Betreuer] Boer. "The rate dependent radiation induced signal degradation of diamond detectors / Florian Robert Kassel ; Betreuer: W. de Boer." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/113602185X/34.
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Batchu, Sudha Rani. "Photo Degradation of Cotnaminants of Emerging concern (CECs) under Simulated Solar Radiation: Implications for their Environmental Fate." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/859.
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Contaminants of emerging concern (CECs) are continuously being released into the environment mainly because of their incomplete removal in the sewage treatment plants (STPs). The CECs selected for the study include antibiotics (macrolides, sulfonamides and ciprofloxacin), sucralose (an artificial sweetener) and dioctyl sulfosuccinate (DOSS, chemical dispersant used in the Deepwater Horizon oil spill). After being discharged into waterways from STPs, photo degradation is a key factor in dictating the environmental fate of antibiotics and sucralose. Photodegradation efficiency depends on many factors such as pH of the matrix, matrix composition, light source and structure of the molecule. These factors exert either synergistic or antagonistic effects in the environment and thus experiments with isolated factors may not yield the same results as the natural environmental processes. Hence in the current study photodegradation of 13 CECs (antibiotics, sucralose and dicotyl sulfosuccinate) were evaluated using natural water matrices with varying composition (deionized water, fresh water and salt water) as well as radiation of different wavelengths (254 nm, 350 nm and simulated solar radiation) in order to mimic natural processes. As expected the contribution of each factor on the overall rate of photodegradation is contaminant specific, for example under similar conditions, the rate in natural waters compared to pure water was enhanced for antibiotics (2-11 fold), significantly reduced for sucralose (no degradation seen in natural waters) and similar in both media for DOSS. In general, it was observed that the studied compounds degraded faster at 254 nm, while when using a simulated sunlight radiation the rate of photolysis of DOSS increased and the rates for antibiotics decreased in comparison to the 350 nm radiation. The photo stability of the studied CECs followed the order sucralose > DOSS > macrolides > sulfonamides > ciprofloxacin and a positive relationship was observed between photo stability and their ubiquitous presence in natural aquatic matrices. An online LC-MS/MS method was developed and validated for sucralose and further applied to reclaimed waters (n =56) and drinking waters (n = 43) from South Florida. Sucralose was detected in reclaimed waters with concentrations reaching up to 18 µg/L. High frequency of detection (> 80%) in drinking waters indicate contamination of ground waters in South Florida by anthropogenic activity.
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Ozdemir, Tonguc. "Effect Of Ionizing Radiation On Different Polymers And Possible Use Of Polymers In Radioactive (nuclear) Waste Management." Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607296/index.pdf.
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In this study three polymers, namely poly(carbonate urethane), poly(bisphenol-a-epichlorohydrin) and poly(methyl methacrylate), were selected and change of properties with gamma treatment were studied. Two different dose rates were used for irradiations and the properties of the
irradiated polymers exposed to same total absorbed dose were compared. In addition, long irradiations of up to about six months with high dose rate were done in order to understand the radiation stability of the polymers,
which may be possible candidates for embedding media for low and intermediate level radioactive (nuclear) waste before their final disposal.
Tensile, DSC, DMA, TGA, FTIR-ATR, FTIR tests were completed to understand the degradation of the polymers as a function of dose rate and total absorbed dose.
The DSC and FTIR results showed that there was not much structural chemical changes in polymer chains with irradiation. However, the changes in mechanical properties were recorded.
It was concluded that poly(carbonate urethane) and poly(bisphenol-aepichlorohydrin) can possibly be used in conditioning of radioactive waste, as they are radiation stable polymers. However, due to the moderate resistance of poly(methyl methacrylate) to ionizing radiation, it can be used
for low level radioactive waste conditioning.
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Mitov, Svetlin. "In-situ radiation grafting of polymer films and degradation studies of monomers for applications in fuel cell membranes." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29662.
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Hacioglu, Firat. "Degradation Of Epdm Via Gamma Irradiation And Possible Use Of Epdm In Radioactive Waste Management." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612391/index.pdf.
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In this study, degradation of ethylene propylene diene terpolymer (EPDM) via gamma radiation and possible use of EPDM in radioactive waste management were investigated. In estimation of radiation stability and possible use of EPDM in radioactive waste management, dose rate (both high and low), irradiation environment (in water and in air), additives (carbon black, zinc oxide, plasticizer) used in formulation, peroxide type (either aliphatic or aromatic) and content were parameters which were analyzed.
Three EPDM samples having different peroxides were irradiated in water and in air with two different dose rates (993 Gy/h, 54 Gy/h) to 2163 kGy (for high dose rate) and 1178 kGy (for low dose rate). Irradiation periods for low dose rate were 2.5 years (last sample) which have not been observed in literature. Characterization of irradiated EPDM samples were done by mechanical (tensile, hardness, compression), dynamic mechanical (DMA), thermal (TGA-FTIR) and morphological (ATR-FTIR, XRD, SEM) tests. High dose rate irradiations were done in predicting how far EPDM resist to radiation and which dose rate emitted waste can be immobilized and stored in EPDM for 300 years. Low dose rate irradiations were carried out in determining morphological changes in structure, thermal stability, oxygen effect and types of reactions (crosslinking, chain scisson) which were dominant in irradiated samples.
According to the test results, improvement in thermal properties and decrease in elasticity on EPDM via radiation were recorded from thermal and mechanical tests respectively. Moreover, structural changes were monitored from ATR-FTIR, SEM and XRD analysis. Mechanical tests showed that irradiated EPDM samples, which were differentiated with respect to peroxide type (aliphatic, aromatic), could resist up to total absorbed doses of 3750 kGy and 3955 kGy respectively. Up to 1178 kGy in low dose irradiation, there were not much structural changes, which were observed in ATR-FTIR analysis, in EPDM chain.
It was concluded that EPDM rubber used in this study were radiation stable polymer so that they could possibly be used in conditioning of radioactive waste.
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Coralli, Irene. "Analysis of chemical degradation of caffeine in aqueous solution using an advanced oxidation process: Fenton's reagent and UV radiation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17964/.
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The present study is aimed to analyse the degradation of caffeine in water employing an advanced oxidation process, the photo-Fenton reaction (H2O2/Fe2+/UV). Different concentrations of H2O2 and Fe2+ are used to evaluate the effects of the two reagents on the quality of the water after the reaction and on the kinetics of degradation. The quality of the water is estimated in terms of conductivity, turbidity, colour and aromaticity. These quantities were found to be not dependent on H2O2 concentrations, whereas the Fe2+ concentration affects them in a proportional way. Compared to the limits of European Directives, the resulting conductivity is acceptable. Turbidity and colour exceed the limits, and the observed influence of the catalyst suggests that they are due to iron species, not to reaction products. Finally, the method employed to evaluate the aromaticity, based on absorbance at 254 nm, does not seem to be reliable. The kinetics of degradation are elaborated through measurements of the absorbance at 272 nm as a function of time. The dependence of the reaction rate on H2O2 concentration observed here is small, but even the lowest concentration employed is 16 times larger than that of caffeine. When the H2O2 concentration is kept constant, a nearly direct proportionality results between reaction rates and Fe2+ doses. Further analyses have shown that caffeine can also be degraded only under UV-visible irradiation (no reagents), but the reaction would need a very long time (6% in 45 minutes). With the addition of Fe2+ (without H2O2) the reaction rate was found somewhat higher, while with the addition of only H2O2 (without Fe2+) the photo-degradation rate was found to be 2/3 of that measured using both reagents. Therefore, the Fe2+ catalyst contributes to the degradation, but dissociation of the perossidic O-O bond of H2O2 to give OH• radicals can also be directly caused by UV irradiation.
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Heffner, Kenneth Henry. "Radiation Induced Degradation Pathways for Poly (Methyl Methacrylate) and Polystyrene Polymers as Models for Polymer Behavior in Space Environments." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000175.
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Graça, Cátia Alexandra Leça. "DEGRADATION OF PERSISTENT PESTICIDES VIA ADVANCED OXIDATION AND REDUCTIVE PROCESSES." Doctoral thesis, Universidade de São Paulo, 2017. http://hdl.handle.net/10362/48570.
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In this Thesis either advanced oxidation or reductive processes are investigated for the degradation of two pesticides considered persistent in the environment: amicarbazone (AMZ) and chlorpyrifos (CP). In chapter I, different advanced oxidation processes (AOPs) driven by sulfate (SO4o-) and hydroxyl radicals (oOH) were applied to the degradation of AMZ. In the first study, several persulfate (PS) activated reactions were explored for AMZ degradation, namely activation with UVA radiation, Fe(II) and H2O2, as well as the combination of UVA radiation with Fe(II), Fe(III) and Fe(III)-complexes. Here, the influence of different reaction variables, such as solution pH, reactants and pesticide initial concentrations, addition of a second oxidant (H2O2) and the addition of different iron catalysts were also investigated. Control experiments regarding the photolysis of iron species in the absence of PS captured our interest and, with the aim of exploring more deeply this process on AMZ degradation, a second investigation was carried out. In this second study, a Doehlert experimental design was applied to investigate the simultaneous effects of two variables on AMZ degradation: pH and Fe(III):carboxylate ratio, where the carboxylate could be oxalate, citrate or tartrate. A response surface model for the observed degradation rate (kobs) as a function of pH and Fe(III):carboxylate ratio was obtained. The processes explored in both aforementioned studies revealed to be effective for AMZ removal, although nothing is known yet about their effectiveness regarding toxicity removal. Given that, a third study was carried out, where the toxicity of AMZ solutions, before and after submission to the processes studied was evaluated towards five microorganisms: Vibrio fischeri (acute toxicity), Tetrahymena thermophile, Chlorella vulgaris (chronic toxicity), Escherichia coli and Bacilus subtilis (antimicrobial activity). The last investigation detailed in chapter I is related with the application of zero-valent-metals on PS activation, which is a subject that links this chapter with the following one. For that, zero-valent-iron (ZVI) was investigated as a PS activator and the influence of variables that help to assess the environmental applicability of this process. In general, organochlorine pesticides reveal a higher resistance to oxidation than reduction, the latter process preferred when the aim is to degrade that important class of contaminants. Therefore, in chapter II the reductive degradation of CP by means of zero-valent-metals and bimetallic particles was investigated. ZVI has been extensively applied for that purpose. However, besides iron, other zero-valent metals can be potential reactive materials for reductive degradation and hence, in this study, the effectiveness of Zn0 and Cu0 was also explored in comparison to that widely reported for ZVI. Furthermore, two different ways of enhancing metals reactivity were here explored: i) by coating ZVI or Zn0 with a more noble metal (Cu), in order to analyze the copper catalytic effect on the bimetallic system; ii) by different surface pretreatments.Na presente Tese de Doutorado foram abordados tanto processos oxidativos avançados (POA), como processos redutivos por metais de valência zero, na degradação de dois pesticidas considerados persistentes no meio ambiente: amicarbazona (AMZ) e clorpirifós (CP). No capítulo I são apresentados os estudos realizados com diversos POA, mediados por radicais sulfato (SO4o-) e hidroxila (oOH), aplicados da AMZ. Num primeiro estudo foi explorada a ativação do oxidante persulfato (PS), de diferentes formas, tais como radiação UVA, H2O2 e Fe(II), assim como a combinação de radiação UVA com Fe(II), Fe(III) e complexos de Fe(III). Aqui também foram investigados os efeitos de diversas variáveis reacionais, tais como pH, concentração inicial de reagentes e de pesticida, adição de um segundo oxidante (H2O2) e adição de diferentes espécies de ferro. Os testes realizados, para efeito de controle, referentes à irradiação das espécies de Fe(III) na ausência de PS, despertaram o interesse para um estudo mais aprofundado sobre o efeito da fotólise destas espécies na degradação da AMZ, surgindo assim o segundo trabalho. Neste utilizou-se um projeto experimental de Doehlert, para avaliar o efeito de duas variáveis em simultâneo quanto à degradação da AMZ: pH e proporção Fe(III): ligante, sendo o ligante um dos seguintes carboxilatos: oxalato, citrato ou tartarato. Um modelo de superfície de resposta, que correlaciona a taxa de degradação observada (kobs) em função do pH e proporção Fe(III):ligante foi obtido para cada um dos complexos de Fe(III) estudados. Os processos explorados, tanto no primeiro como no segundo estudo, se mostraram eficazes na remoção da AMZ, porém nada se sabe acerca da remoção da toxicidade. Para tal, foi desenvolvido um terceiro estudo dedicado à avaliação da toxicidade da solução de AMZ, antes e após a aplicação de cada um dos processos anteriormente abordados, contra cinco micro-organismos: Vibrio fischeri (toxicidade aguda); Tetrahymena thermophila, Chlorella vulgaris (toxicidade crônica); Escherichia coli e Bacilus subtilis (atividade antimicrobiana). O último estudo abordado no capitulo I é referente à aplicação de metais de valência zero também nos POA, correlacionado assim o capítulo I e o capítulo II. Como tal, foi feito um estudo de ativação de PS por meio de ferro de valência zero (Fe0), em que se investigou a influência de diversas variáveis por forma a inferir sobre a aplicabilidade prática deste processo. Pesticidas organoclorados apresentam maior resistência à degradação por processos oxidativos do que redutivos, sendo preferível o último na degradação desta importante classe de contaminantes. Como tal, o capítulo II se refere à degradação redutiva, por meio de diferentes metais de valência zero e partículas bimetálicas, do pesticida organoclorado CP. Além do amplamente explorado Fe0, outros metais podem ser aplicados neste processo, pelo que, neste estudo, explorou-se a potencialidade de Zn0 e Cu0 comparativamente ao primeiro. Ainda neste estudo foram investigadas duas formas de aumentar a reatividade dos metais: i) no caso do Fe0 e Zn0, revestindo com um metal mais nobre (Cu), por forma a observar o efeito catalisador do último no sistema bimetálico; ii) realizando um pré-tratamento à superfície dos metais.
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Souza, Clécia de Moura. "Utilização da radiação ionizante na reciclagem de pneus inservíveis de automóvel e sua destinação ambiental adequada." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-17022014-131803/.
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O objetivo deste trabalho foi utilizar a radiação ionizante na reciclagem de pneus inservíveis de automóvel. As amostras de borracha de pneus inservíveis foram irradiadas com doses de radiação de 200, 400 e 600kGy, em um acelerador de elétrons. Posteriormente, elas foram caracterizadas por termogravimetria (TG), calorimetria exploratória diferencial (DSC), ensaios mecânicos de tração, espectrofotometria de infravermelho por transformada de Fourier (FTIR) e microscopia eletrônica de varredura (MEV). Por TG foi possível observar os efeitos da radiação na perda de massa do material. Por DSC observou-se as curvas exotérmicas associadas à decomposição e valores de variação de entalpia (ΔH). Foram estudadas as propriedades mecânicas das amostras da matriz elastomérica com o pó de pneu inservível e verificado o seu comportamento frente à radiação ionizante. Os espectros FTIR foram obtidos na região de 4000 650cm-1. Observou-se que não foi possível observar alteração nos picos devido à irradiação. Nos ensaios por MEV as micrografias foram ampliadas de 32 vezes até 1000 vezes e observadas nos tamanhos de 1mm até 20μm. Observou-se nas doses de 200 e 400kGy, rugosidades correspondentes a quebras ou rupturas, possivelmente causadas pela radiação. Na dose de 600kGy, foi possível observar cavidades causadas pela radiação. Observou-se que para todas as doses houve degradação. Para as amostras dos corpos de prova sem pó e com pó de pneus inservíveis com 10%, 30% e 50% de pó as micrografias foram observadas nas ampliações de 100μm e 200μm. Também foi possível observar a incorporação do pó de pneus inservíveis de automóvel na matriz elastomérica das amostras não irradiadas e irradiadas.The aim of this study was to use ionizing radiation in the recycling of scrap tires of automotive. Samples of rubber unserviceable tires were irradiated with radiation doses 200, 400 and 600kGy in an electron accelerator. Subsequently, they were characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), tensile strenght mechanical test, spectrophotometry Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). By thermogravimetry was possible to observe the effects of radiation in the mass loss of material. In the DSC curves were observed exothermic decomposition peaks and associated values of enthalpy variation (ΔH). The mechanical properties of the elastomeric matrix with unserviceable tires powder were studied and its behavior to ionizing radiation was analyzed. FTIR spectra were obtained in the 4000 - 650cm-1 region. It was observed that there was no change in the peaks due irradiation. For SEM the micrographs were enlarged from 32 times up to 1000 times and observed in sizes from 1mm up to 20μm. It was observed at doses of 200 and 400kGy, roughness corresponding to breaks or ruptures possibly caused by radiation. In 600kGy radiation dose was observed cavities caused by radiation. It was observed that at all doses occurred degradation. For samples without powder and with 10, 30 and 50% of unserviceable tires powder it was obtained micrographs of 100μm and 200μm amplification. Also it was possible to observe the incorporation of unserviceable tires powder of automotive in the elastomeric matrix of non-irradiated and irradiated samples.
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Graça, Cátia Alexandra Leça. "Degradation of persistent pesticides via advanced oxidation and reductive processes." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-03082017-091224/.
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In this Thesis either advanced oxidation or reductive processes are investigated for the degradation of two pesticides considered persistent in the environment: amicarbazone (AMZ) and chlorpyrifos (CP). In chapter I, different advanced oxidation processes (AOPs) driven by sulfate (SO4o-) and hydroxyl radicals (oOH) were applied to the degradation of AMZ. In the first study, several persulfate (PS) activated reactions were explored for AMZ degradation, namely activation with UVA radiation, Fe(II) and H2O2, as well as the combination of UVA radiation with Fe(II), Fe(III) and Fe(III)-complexes. Here, the influence of different reaction variables, such as solution pH, reactants and pesticide initial concentrations, addition of a second oxidant (H2O2) and the addition of different iron catalysts were also investigated. Control experiments regarding the photolysis of iron species in the absence of PS captured our interest and, with the aim of exploring more deeply this process on AMZ degradation, a second investigation was carried out. In this second study, a Doehlert experimental design was applied to investigate the simultaneous effects of two variables on AMZ degradation: pH and Fe(III):carboxylate ratio, where the carboxylate could be oxalate, citrate or tartrate. A response surface model for the observed degradation rate (kobs) as a function of pH and Fe(III):carboxylate ratio was obtained. The processes explored in both aforementioned studies revealed to be effective for AMZ removal, although nothing is known yet about their effectiveness regarding toxicity removal. Given that, a third study was carried out, where the toxicity of AMZ solutions, before and after submission to the processes studied was evaluated towards five microorganisms: Vibrio fischeri (acute toxicity), Tetrahymena thermophile, Chlorella vulgaris (chronic toxicity), Escherichia coli and Bacilus subtilis (antimicrobial activity). The last investigation detailed in chapter I is related with the application of zero-valent-metals on PS activation, which is a subject that links this chapter with the following one. For that, zero-valent-iron (ZVI) was investigated as a PS activator and the influence of variables that help to assess the environmental applicability of this process. In general, organochlorine pesticides reveal a higher resistance to oxidation than reduction, the latter process preferred when the aim is to degrade that important class of contaminants. Therefore, in chapter II the reductive degradation of CP by means of zero-valent-metals and bimetallic particles was investigated. ZVI has been extensively applied for that purpose. However, besides iron, other zero-valent metals can be potential reactive materials for reductive degradation and hence, in this study, the effectiveness of Zn0 and Cu0 was also explored in comparison to that widely reported for ZVI. Furthermore, two different ways of enhancing metals reactivity were here explored: i) by coating ZVI or Zn0 with a more noble metal (Cu), in order to analyze the copper catalytic effect on the bimetallic system; ii) by different surface pretreatments.Na presente Tese de Doutorado foram abordados tanto processos oxidativos avançados (POA), como processos redutivos por metais de valência zero, na degradação de dois pesticidas considerados persistentes no meio ambiente: amicarbazona (AMZ) e clorpirifós (CP). No capítulo I são apresentados os estudos realizados com diversos POA, mediados por radicais sulfato (SO4o-) e hidroxila (oOH), aplicados da AMZ. Num primeiro estudo foi explorada a ativação do oxidante persulfato (PS), de diferentes formas, tais como radiação UVA, H2O2 e Fe(II), assim como a combinação de radiação UVA com Fe(II), Fe(III) e complexos de Fe(III). Aqui também foram investigados os efeitos de diversas variáveis reacionais, tais como pH, concentração inicial de reagentes e de pesticida, adição de um segundo oxidante (H2O2) e adição de diferentes espécies de ferro. Os testes realizados, para efeito de controle, referentes à irradiação das espécies de Fe(III) na ausência de PS, despertaram o interesse para um estudo mais aprofundado sobre o efeito da fotólise destas espécies na degradação da AMZ, surgindo assim o segundo trabalho. Neste utilizou-se um projeto experimental de Doehlert, para avaliar o efeito de duas variáveis em simultâneo quanto à degradação da AMZ: pH e proporção Fe(III): ligante, sendo o ligante um dos seguintes carboxilatos: oxalato, citrato ou tartarato. Um modelo de superfície de resposta, que correlaciona a taxa de degradação observada (kobs) em função do pH e proporção Fe(III):ligante foi obtido para cada um dos complexos de Fe(III) estudados. Os processos explorados, tanto no primeiro como no segundo estudo, se mostraram eficazes na remoção da AMZ, porém nada se sabe acerca da remoção da toxicidade. Para tal, foi desenvolvido um terceiro estudo dedicado à avaliação da toxicidade da solução de AMZ, antes e após a aplicação de cada um dos processos anteriormente abordados, contra cinco micro-organismos: Vibrio fischeri (toxicidade aguda); Tetrahymena thermophila, Chlorella vulgaris (toxicidade crônica); Escherichia coli e Bacilus subtilis (atividade antimicrobiana). O último estudo abordado no capitulo I é referente à aplicação de metais de valência zero também nos POA, correlacionado assim o capítulo I e o capítulo II. Como tal, foi feito um estudo de ativação de PS por meio de ferro de valência zero (Fe0), em que se investigou a influência de diversas variáveis por forma a inferir sobre a aplicabilidade prática deste processo. Pesticidas organoclorados apresentam maior resistência à degradação por processos oxidativos do que redutivos, sendo preferível o último na degradação desta importante classe de contaminantes. Como tal, o capítulo II se refere à degradação redutiva, por meio de diferentes metais de valência zero e partículas bimetálicas, do pesticida organoclorado CP. Além do amplamente explorado Fe0, outros metais podem ser aplicados neste processo, pelo que, neste estudo, explorou-se a potencialidade de Zn0 e Cu0 comparativamente ao primeiro. Ainda neste estudo foram investigadas duas formas de aumentar a reatividade dos metais: i) no caso do Fe0 e Zn0, revestindo com um metal mais nobre (Cu), por forma a observar o efeito catalisador do último no sistema bimetálico; ii) realizando um pré-tratamento à superfície dos metais.
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Yermalayeva, Darya. "Vliv radiace na vlastnosti polovodičových součástek." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377051.
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This master’s thesis deals with the problematics of influence of ionizing radiation on semiconductor devices and their properties. The aim of the thesis is to analyze the different types of radiation that can occur in the areas of application of these components. In the second part, the degradation processes are explored, with emphasis on the influence caused by the radiation dose. Also, the displacement damage and SEE effects are described, but just slightly, because they are not part of this work. The third part describes the device design process and harmful effects, that have to be considered during the design phase. In the forth and the fifth parts of this work were done modeling of radiation effects (influence of dose rate, Single-Event Upset and Total Ionizing Dose) in PSpice program and was carried out the possibility of designing a simple dosimeter with silicon diode. In conclusion, the results of the thesis are summarized and evaluated.
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Araujo, Leandro Goulart de. "Photo-oxidative degradation of bisphenol A by H2O2/UV: process study and kinetic modelling." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-17072018-111837/.
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Bisphenol A (BPA) is widely used in the production of plastics, epoxy resins and polycarbonates. It is a toxic, endocrine disruptor compound. Different studies have shown the presence of BPA in several environmental systems, classifying it as a worldwide persistent pollutant which may act synergistically with other pollutants. In this context, advanced oxidation processes (AOP) have received great attention due to their ability to degrade pollutants with such characteristics, through their transformation into less hazardous compounds or even their mineralization. Although there are investigations on the use of AOPs for BPA degradation, systematic studies on the effects of process variables, coupled with the statistical interpretation of the results are virtually non-existent. Furthermore, to the best of our knowledge, a rigorous kinetic model has not yet been proposed for the degradation of this pollutant by the H2O2/UV process. The objective of this work was to evaluate BPA degradation by the H2O2/UV process, investigating the effects of the initial H2O2 concentration and the specific rate of photons emission (EP,0) by means of a Doehlert experimental design, combined with the response surface methodology. The experiments were performed in a photochemical tubular reactor equipped with a 254-nm UV lamp, for [H2O2]0 and EP,0 in the ranges 1.6-9.6 mmol L-1 and 0.87 × 1018-3.6 × 1018 photons L-1 s-1, respectively. Total BPA degradation was achieved after 60 min of irradiation in all experiments. The best conditions were [H2O2]0 = 7.6 mmol L-1 and EP,0 = 3.6 × 1018 photons L-1 s-1, for which the best performance was obtained regarding the BPA degradation rate, BPA degradation after 15 min, and the second highest TOC removal after 180 min. However, in most experiments less than 75% TOC removal was observed, with 95% mineralization obtained only for the superior [H2O2]0 and EP,0. A mathematical model was developed, considering the reactor characteristics and the radiation field, based on the line source with parallel emission (LSPP) approach, in combination with the radiative transfer equation (RTE), mass balances, and a detailed kinetic model of the H2O2/UV process. The steady-state approximation was applied for all radical species. In the estimation of unknown kinetic constants, the non-linear least squares method was employed. The model was able to satisfactorily fit experimental BPA and H2O2 concentrations as a function of time. This work shows that the H2O2/UV process is a good alternative for BPA removal from aqueous streams, with total degradation of the target compound and adequate percent mineralization under optimal operating conditions. Such conditions may serve as first guidelines for pilot-plant and industrial processes operation. In addition, simulations using the proposed kinetic model may provide useful information for the design and scale-up of pre- or post-treatment of effluents containing this pollutant.O bisfenol A (BPA) é amplamente utilizado na fabricação de plásticos, resinas epóxi e policarbonatos. Trata-se de um composto tóxico e um desregulador endócrino. Diferentes estudos evidenciam a presença do BPA em diversos compartimentos ambientais em todo planeta, identificando-o como um poluente persistente e resistente à degradação biológica, que apresenta efeitos sinergéticos com outros poluentes. Nesse contexto, os processos oxidativos avançados (POA) têm recebido atenção devido a sua capacidade em degradar poluentes com tais características, transformando-os em compostos menos perigosos ou até mesmo mineralizando-os totalmente. Apesar de haver trabalhos na literatura acerca da utilização de POA para degradação de BPA, estudos sistemáticos dos efeitos de variáveis de processo junto com a interpretação estatística dos resultados são virtualmente inexistentes. Além disso, até onde se sabe um modelo cinético rigoroso ainda não foi proposto para a degradação desse poluente por meio do processo H2O2/UV. Este trabalho teve por objetivo avaliar a degradação do BPA pelo processo H2O2/UV, investigando os efeitos da concentração inicial de H2O2 e da taxa específica de emissão de fótons (EP,0) por meio de um projeto experimental Doehlert, combinado com a análise de superfície de resposta. Os experimentos foram realizados em um reator tubular fotoquímico equipado com uma lâmpada UV de 254 nm, para [H2O2]0 e EP,0 entre 1,6-9,6 mmol L-1 e 0,87 × 1018 - 3,6 × 1018 fótons L-1 s-1, respectivamente. Todos os experimentos sob H2O2/UV resultaram em total degradação do BPA após 60 min de irradiação. Nesse caso, as melhores condições foram [H2O2]0 = 7,6 mmol L-1 e EP,0 = 3,6 × 1018 fótons L-1 s-1, para as quais se obteve o melhor desempenho quanto à taxa de degradação de BPA e à remoção após 15 min, e a segunda maior remoção de COT após 180 min. Entretanto, na maioria dos experimentos menos de 75% de remoção de COT foram observados, com 95% de mineralização obtida apenas para os maiores [H2O2]0 e EP,0. Elaborou-se um modelo matemático que considera as características do reator utilizado e o campo de radiação, baseado no modelo de fonte linear de emissão em planos paralelos (LSPP), combinado à equação de transferência radiativa (RTE), aos balanços materiais e a um modelo cinético detalhado do processo H2O2/UV. Foi empregada a aproximação de estado estacionário para todas as espécies radicalares. Na estimativa das constantes cinéticas desconhecidas, utilizou-se o método de mínimos quadrados não linear. Esse modelo foi capaz de ajustar satisfatoriamente as concentrações experimentais de BPA e de H2O2 em função do tempo. Este trabalho mostra que o processo H2O2/UV constitui uma alternativa conveniente para a degradação de BPA em matrizes aquosas, com total degradação do composto alvo e porcentagem de mineralização adequada nas condições ótimas de operação. Tais condições podem servir como diretrizes iniciais de processamento em escalas piloto e industrial. Por sua vez, simulações empregando o modelo matemático proposto permitem gerar informações úteis para projeto e aumento de escala de processos de pré- ou pós-tratamento de efluentes contendo esse poluente.
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Wagner, Anthony Jon. "Degradation of fluorine-containing organic thin films and organohalides mediated by ionizing radiation nitrogen-based surface modification of polymers and metallization of nitrogen-containing polymers /." Available to US Hopkins community, 2003. http://wwwlib.umi.com/dissertations/dlnow/3080788.
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GONÇALVES, Gonçalves. "Nanofibras de poli(ε-caprolactona) e poli(óxido de etileno): fabricação pela técnica de eletrofiação e efeitos radiolíticos." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16683.
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FACEPE
O poli(ε-caprolactona) (PCL) é um poliéster biocompatível, biodegradável e semicristalino utilizado na confecção de artefatos médico-farmacêuticos, especialmente como suporte para cultivo de células e tecidos. Por outro lado, sua hidrofobicidade e baixas taxas de hidrólise in vivo impedem a expansão do uso destes polímeros em aplicações biológicas. Nesta pesquisa, empregamos três estratégias na tentativa de aumentar a taxa de hidrólise da PCL: a) preparação do material em morfologia fibrilar, para aumentar a superfície de contato com o meio; b) irradiação com raios gama, para induzir dano molecular e acelerar a hidrólise; e c) blenda com o polímero hidrofílico e lixiviável poli(óxido de etileno) (PEO), para aumentar a molhabilidade e permitir maior percolação da água. Tapetes de PCL, apresentando nanofibras com diâmetros menores que 100nm e de microfibras com diâmetros entre 1,9 e 7,5μm da blenda PCL/PEO 10% m/m foram preparados pela técnica de eletrofiação, irradiados com raios gama em doses de 25 e 50kGy e submetidos à hidrólise por submersão em tampão fosfato salino (PBS) pH 7,4 a 37 0C. Para comparação, filmes de PCL e da blenda de PCL/PEO foram confeccionados por derrame em solução (film casting) e submetidos ao mesmo tratamento. Nada se pode afirmar sobre as mudanças de Massa Molar Viscosimétrica Média (Mv) em filmes de PCL irradiados, pois não foi possível observar nem o efeito de cisão, nem reticulação da cadeia principal. A irradiação gama não influenciou nas propriedades térmicas dos filmes de PCL e os cálculos de energia de ativação para reações de decomposição térmica evidenciaram que filmes de PCL têm boa estabilidade térmica. Ensaios espectrométricos no Infravermelho com Transformada de Fourier (FTIR) e difratométricos de raios X dos filmes de PCL não foi possível observar mudanças significativas de estrutura molecular ou cristalinidade com a irradiação gama. As estratégias adotadas para melhorar a degradação hidrolítica do PCL funcionaram. Blendas de PCL/PEO (10% m/m) apresentaram taxa de degradação hidrolítica maiores do que as amostras de PCL, tanto na forma de tapetes microfibrilares eletrofiados como na forma de filmes espessos. Sendo a primeira com taxa de degradação mais acentuada. A irradiação gama exerce influência significativa na degradação hidrolítica apenas em blendas PCL/PEO na forma de filmes. A degradação hidrolítica dos filmes de PCL se mostrou muito lenta, não sendo possível observar diferenças significativas entre amostras irradiadas e não irradiadas.
Poly (ε-caprolactone) (PCL) is a biocompatible, biodegradable, semicrystalline polyester used in medical-pharmaceutical devices, specially as scaffolds in cell and tissue culture. Nevertheless, its hydrophobicity and low in vivo hydrolysis rates are obstacles to the expansion of its use in biological applications. In this work, we designed three strategies to address PCL hydrophobicity issues: a)prepare electrospun fibers to enhace contact surface with aqueous media; b)irradiation with gamma rays to induce molecular damage and increase hydrolysis rate; and c) blending with the hydrophilic, leacheble polymer poly(ethylene oxide) (PEO), in order to increase wettability and allow larger water percolation rates. Mats of PCL electrospun nanofiber with less than 100nm in diameter; and of electrospun PCL/PEO (10%wt) blend microfibers presenting diameters in the range of 1.9 - 7.5 μm were irradiated with gamma rays in 25 and 50 kGy dose and submitted to in vitro hydrolysis in phosphatebuffered saline (PBS) solution, pH 7,4 at 37 0C. PCL and PCL/PEO (10%wt) films were also prepared by film casting and treated in the same way, for comparison. Nothing can be said about mass changes Viscosity Average Molar Mass (Mv) in irradiated PCL films because it was not possible to observe nor the effect of spin-off, or crosslinking of the backbone. Good thermal stability was also evidenced by calculations of activation energy for thermal degradation of PCL. Fourier Transform Infrared espectrometry and X-ray difractometry data did not evidence significant changes in molecular structure or crystallitiny of PCL after irradiation. Strategies to improve PCL in vitro hydrolysis degradation rate were successful. Blends of PCL/PEO (10% wt) presented higher hydrolysis rates than PCL samples, either in mat fibers or film forms. Hydrolysis degradation of PCL films was very slow, and no differences between non irradiated or irradiated samples were observed.
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ROMANO, REBECA da S. G. "Estudo da irradiação do polipropileno para possibilitar o controle de sua degradação ambiental." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28012.
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O PP é descartado em grande quantidade no meio ambiente, tendo em vista seu consumo muito elevado derivado de suas excelentes propriedades químicas e físicas, boa processabilidade e baixo custo. As radiações ionizantes, não ionizantes (UV e infravermelho), bem como o oxigênio e os poluentes podem causar a degradação do polipropileno (PP). A exposição à radiação ionizante pode causar na molécula de PP cisão de cadeia principal, reticulação e peroxidação (na presença de ar) entre outras. Este estudo tem como objetivo, o desenvolvimento de um PP oxidegradável por meio do controle da degradação induzida por radiação ionizante. As amostras foram processadas por injeção e expostas ao envelhecimento natural durante 180 dias e ao envelhecimento acelerado em estufa á 100°C por 192 dias e depois caracterizadas por avaliação visual, ensaios mecânicos, FTIR, SEM, DSC, TGA e DRX. As amostras de PP Grão 20 kGy, após o envelhecimento natural, apresentaram maior oxidação com presença de fissuras superficiais mais intensamente do que o PP d2w®. A resistência a tração do PP irradiado foi superior ao PP d2w® e os resultados do alongamento na ruptura mostraram uma diminuição intensa se compararmos o PP irradiado e o PP d2w® com o PP. Após a exposição natural espécies os índices de vinila e carbonila aumentaram ligeiramente devido as reações Norrish. O grupo carbonila promove uma oxidação contínua, junto à superfície fazendo com que o polímero diminua sua massa molar. O efeito da degradação natural foi evidente na ordem PP Grão 20 kGy > PP Grão 12,5 kGy = PP d2w® > PP. Por conseguinte, este conceito pode ser utilizado para produzir um PP com propriedades oxi-degradáveis de uma forma controlável.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Silva, Vanessa Honda Ogihara. "Avaliação da toxicidade e da degradação do fármaco cloridrato de fluoxetina, em solução aquosa e em mistura com esgoto doméstico, empregando irradiação com feixe de elétrons." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-22042014-155700/.
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A ampla utilização de medicamentos, a falta de gerenciamento na produção e no descarte desses produtos, bem como a dificuldade na remoção de resíduos de fármacos das águas residuais durante as fases do tratamento de efluentes tem causado a liberação destes micropoluentes nos recursos hídricos. O cloridrato de fluoxetina, conhecido comercialmente como Prozac®, tem sido muito utilizado em diversos países. Estudos demonstram sua presença no meio ambiente e o potencial de danos que este fármaco pode causar à biota. Desta forma, este trabalho estudou uma tecnologia de tratamento (POA - Processo Oxidativo Avançado) utilizando-se radiação ionizante, proveniente de um acelerador de elétrons, para a degradação do fármaco cloridrato de fluoxetina em solução aquosa e na mistura com esgoto doméstico. Após a irradiação foram feitas análises químicas na solução aquosa do fármaco com Espectrofotometria UV/VIS, Cromatografia Líquida Ultra Rápida (detectores UV/VIS e fluorescência) e quantificação do Carbono Orgânico Total (COT). Também foram empregados ensaios de toxicidade aguda (Daphnia similis e Vibrio fischeri) e crônica (Ceriodaphnia dubia). A eficiência na degradação do fármaco foi superior a 98,00% na menor dose de radiação (0,5 kGy), porém houve baixa taxa de mineralização para as doses aplicadas neste estudo. Para a Daphnia similis na dose de 0,5 kGy houve eficiência de 83,75% na redução da toxicidade do cloridrato de fluoxetina e 87,24% para 5,0 kGy, houve eficiência de 100,00% na redução da toxicidade para o esgoto doméstico e para a mistura (CF + esgoto) 79,32% na dose de 5,0 kGy. A eficiência para a Vibrio fischeri foi de 17,26% (melhor eficiência na dose de 5,0 kGy) e após a correção do pH das amostras a melhor eficiência foi para 20,0 kGy (26,78%), para o esgoto e para a mistura as eficiências ficaram em torno dos 20,00% para todas as doses de radiação aplicadas. Em relação a toxicidade crônica para Ceriodaphnia dubia a eficiência foi de 97,50% para 5,0 kGy. Verificou-se que a Ceriodaphnia dubia possui maior sensibilidade ao fármaco, seguido da bactéria Vibrio fischeri e por fim a Daphnia similis.Extensive use of drugs, lack of management in the production and disposal of these products as well as the difficulty in removing residues of pharmaceuticals during wastewater treatment phases imply the release of these micropollutants in water resources. Fluoxetine hydrochloride, known commercially as Prozac®, have been often used in many countries. Studies demonstrate their presence in the environment and potential damage that this drug may cause the biota. Therefore, this paper studied a treatment technology (AOP - Advanced Oxidative Process) using ionizing radiation from an electron accelerator, for the degradation of the drug fluoxetine hydrochloride in aqueous solution and mixed with domestic sewage. After irradiation at aqueous solution chemical analyzes at the drug were done using spectrophotometry UV/VIS, Ultra Fast Liquid Chromatography (detectors UV/ VIS and fluorescence) and quantification of Total Organic Carbon (TOC). Acute toxicity tests (Daphnia similis and Vibrio fischeri) and chronic (Ceriodaphnia dubia) were employed. The efficiency for the degradation of the drug was greater than 98.00% at the lowest absorbed dose of radiation (0.5 kGy), however there was low rate of mineralization to the doses applied in this study. The efficiency reduction of toxicity was 83.75% using Daphnia similis at 0.5 kGy of absorbed dose and 87.24% at 5.0 kGy to fluoxetine hydrochloride, efficiency was 100.00% in reducing toxicity to domestic sewage and the mixture (CF + sewage) was 79.32% at a dose of 5.0 kGy. The efficiency to Vibrio fischeri was 17.26% (better efficiency at the dose of 5.0 kGy) and after correction of pH to a better performance was 20.0 kGy (26.78%), for sewage and mixture efficiencies were about 20,00% for all doses of radiation applied. In relation to chronic toxicity effects to Ceriodaphnia dubia efficiency was 97.50% at 5.0 kGy. It was verified that Ceriodaphnia dubia is more sensitive to the drug, followed by the bacterium Vibrio fischeri and finally Daphnia similis.
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KOMATSU, LUIZ G. H. "Estudo comparativo de nanocompósitos de polipropileno modificado sob condições de envelhecimento ambiental e acelerado." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26380.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T12:34:18Z
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Poncin-Epaillard, Fabienne. "Etude de la polymerisation induite par plasma froid : interface plasma-polymere, greffage, degradation et modification chimique." Le Mans, 1987. http://www.theses.fr/1987LEMA1028.
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Etude de monomeres liquides ou solides sous l'action des plasmas froids. Influence des parametres du plasma sur la vitesse de polymerisation et la structure chimique de la surface du polymere. Aux interfaces entre le plasma et le polymere, se produisent des reactions qui ont pour origine deux transferts d'energie du plasma. Le transfert indirect, attribue aux rayonnements uv-visible, provoque la polymerisation des acrylates. Le transfert direct, du au bombarbement par des especes metastables, radicaux, ions. . . Sur la surface du polymere, amorce des reactions de modification d'addition ou de terminaison
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Cruz-González, Germán. "Dégradation de pesticides organochlorés par procédés d'oxydation avancée utilisant différents types de rayonnements." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0068/document.
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Ce travail s’intéresse à évaluer l’efficacité de procédés d’oxydation avancée pour l’élimination de pesticides dans l’eau, plus particulièrement l’acide 2,4-dichlorophénoxyacétique (2,4-D), un herbicide largement répandu, qui a été récemment classé comme cancérogène possible pour l’homme. Ces procédés utilisent différents types de rayonnement – UV/visible, ultrasons, rayons gamma –, seuls ou en combinaison avec des oxydants et/ou catalyseurs (ozone, peroxyde d’hydrogène, réactif de Fenton). L'influence du pH, de la dose d'oxydant, du type et de la concentration du catalyseur, du spectre d'irradiation lumineuse, de la dose de rayons gamma et de la fréquence ultrasonore est également analysée, de façon à déterminer par plans d’expériences les plages de fonctionnement optimales pour la conversion et la minéralisation du polluant. Parmi les procédés individuels, seules l’ozonation et l’oxydation Fenton homogène d’une part, la photolyse et l’irradiation gamma d’autre part permettent d’éliminer plus de 25% du carbone organique total en 1 heure. La sonolyse (à haute fréquence) apparaît comme le traitement moins performant, avec une dégradation du 2,4-D inférieure à 15% sur la même durée. Par ailleurs, des effets synergiques marqués sont mis en évidence en associant les différents types de rayonnement avec H2O2 ou le réactif de Fenton. Dans le dernier cas, le polluant est décomposé en moins de 10 minutes, tandis que le rendement de minéralisation est plus que doublé par rapport aux procédés séparés. Il en est de même pour le procédé couplé UV/O3 par rapport à l’ozonation et la photolyse seules. Ramenés à leur consommation énergétique, les traitements les plus efficaces sont, respectivement en termes de conversion et de minéralisation, l’oxydation radio-Fenton et l’oxydation photo-Fenton utilisant une lampe UV à basse pression de mercure. Par ailleurs, contrairement à la photolyse, ce dernier procédé est également activé par une lampe à arc Xenon, dont le spectre d’émission est proche de celui de la lumière du soleil. Sur la base de ces résultats, un photo-réacteur solaire à recirculation est mis en oeuvre pour traiter par oxydation photo-Fenton homogène des solutions de 2,4-D, préparées dans l’eau du robinet ou une eau résiduaire en entrée de station d’épuration. Dans les deux cas, la conversion du pesticide dépasse 95% en 1 heure et sa minéralisation 75% en 5 heures. Par ailleurs, l’eau ainsi traitée respecte tous les paramètres de qualité établis par la norme cubaine de rejet des eaux usées, en incluant une étape successive de neutralisation avec Ca(OH)2 et de filtration. Enfin, plusieurs parmi les meilleurs procédés sont évalués pour éliminer deux autres pesticides organochlorés, particulièrement toxiques et persistants dans l’environnement : le chlordécone et le bêta-hexachlorocyclohexane. Des résultats encourageants sont obtenus, avec une dégradation pratiquement totale des polluants en cinq heures, ce qui démontre l’intérêt des méthodes étudiées pour cette problématiqueThis work investigates the efficacy of advanced oxidation processes for the remediation of pesticidesin water, more particularly 2,4-dichlorophenoxyacetic acid (2,4-D), a widely used herbicide that hasrecently been classified as a possible carcinogen to humans. These methods use different types ofradiation - UV / visible, ultrasound, gamma rays - alone or in combination with oxidants and / orcatalysts (ozone, hydrogen peroxide, Fenton’s reagent). The influence of pH, oxidant dose, catalysttype and concentration, light irradiation spectrum, gamma radiation dose and ultrasound frequencyis also analyzed, in order to determine by experimental design the optimal operating ranges for theconversion and mineralization of the pollutant. Of individual processes, only ozonation andhomogeneous Fenton oxidation on the one hand, photolysis and gamma irradiation on the otherhand, achieve the abatement of more than 25% of total organic carbon in one hour. (High frequency)sonolysis appears as the less efficient treatment, resulting in less than 15% of 2,4-D being degradedover the same duration.In addition, marked synergistic effects are demonstrated by combining the different types of radiationwith H2O2 or Fenton’s reagent. In the latter case, the pollutant is decomposed in less than 10 minutes,while the mineralization yield more than doubles compared to the separate processes. It is the samefor UV/O3 coupled process with respect to ozonation and photolysis alone. When accounting for theirenergy consumption, the most effective treatments are, respectively in terms of conversion andmineralization, radio-Fenton oxidation and photo-Fenton oxidation using a low-pressure mercuryvaporUV lamp. Moreover, unlike photolysis, the latter method is also activated by a Xenon arc lamp,whose emission spectrum is close to that of sunlight. Bases on these results, a solar photoreactoroperating in closed loop is used to treat 2,4-D solutions, prepared with tap water or inlet stream ofwastewater treatment plant, by homogeneous photo-Fenton oxidation. In both cases, the conversionof the pesticide exceeds 95% in 1 hour and its mineralization 75% in 5 hours. Moreover, the treatedwater complies with all the quality parameters established by the Cuban norm for wastewaterdischarge, when including a subsequent step of neutralization with Ca(OH)2 and filtration.Finally, several of the best processes are evaluated to eliminate two other organochlorine pesticides,particularly toxic and persistent in the environment: chlordecone and beta-hexachlorocyclohexane.Encouraging results are obtained, with an almost complete degradation of the pollutants in fivehours, which demonstrates the value of the investigated methods for this issue
En este trabajo se estudió la factibilidad de diferentes procesos avanzados de oxidación para laeliminación de plaguicidas en aguas, específicamente el ácido 2,4-diclorofenoxiacético (2,4-D), unode los herbicidas más utilizados a nivel mundial y que recientemente ha sido clasificado comocancerígeno para el hombre. Estos procesos utilizan diferentes tipos de irradiación – UV/Visible,ultrasonido, radiación gamma – solos o en combinación con oxidantes y/o catalizadores (ozono,peróxido de hidrógeno, reactivo de Fenton). Con el objetivo de determinar las condiciones óptimaspara la degradación y mineralización del contaminante, se analizó la influencia del pH, la dosis deoxidante, el tipo y la concentración del catalizador, el espectro de irradiación luminosa, la dosis deirradiación gamma y la frecuencia y potencia ultrasónicas. Entre los procesos individuales,solamente la oxidación Fenton homogénea, la ozonización, la fotólisis y la radiación gamma lograroneliminar más de un 25% del carbono orgánico total en una hora. La sonólisis (a alta frecuencia)resultó el proceso menos eficiente, con una degradación del 2,4-D inferior al 15% en el mismotiempo.Al asociar los diferentes tipos de irradiación con el H2O2 o el reactivo de Fenton, se observaronefectos sinérgicos importantes. Para este último, el contaminante se degradó totalmente en menosde 10 minutos, mientras que la mineralización fue superior al doble de la obtenida para los procesospor separado. Lo mismo ocurrió para el proceso combinado UV/O3, respecto a los procesos defotólisis y ozonización solos. Teniendo en cuenta el consumo energético asociado a la degradacióny mineralización respectivamente, los tratamientos más eficientes fueron el radio-Fenton y el foto-Fenton utilizando una lámpara de baja presión de mercurio. Por otra parte, al contrario de la fotólisis,este último proceso se activó con una lámpara de arco de Xenon, la cual posee un espectro deemisión cercano a la luz solar. Teniendo en cuenta estos resultados, se realizó un grupo deexperimentos a escala de banco utilizando un foto-reactor solar, donde se trataron por oxidaciónfoto-Fenton homogénea disoluciones de 2,4-D preparadas con agua técnica y agua residualobtenida a la entrada de una planta de tratamiento de aguas. En los dos casos, la degradación delpesticida supera el 95% en 1 hora y su mineralización en 75% en 5 horas. Además, al incluir unaetapa de neutralización con Ca(OH)2, el agua residual tratada logra cumplir las normas de calidadestablecidas por la norma cubana de vertimiento de aguas residuales.Finalmente, algunos de los procesos con mejores resultados se evaluaron para la eliminación otrosdos pesticidas organoclorados de mayor toxicidad y persistencia en el medio ambiente: laclordecona y el beta hexaclorociclohexano. Al aplicar las técnicas de tratamiento a estoscompuestos se lograron buenos resultados, cercanos a la degradación total de ambos plaguicidasen cinco horas, lo que demuestra el interés de los métodos estudiados en esta tesis
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Güere, Carlos Dante Gamarra. "Estudo da degradação do metil parabeno utilizando processos Fenton, foto-Fenton e eletro-Fenton." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-21112014-160153/.
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Os disruptores endócrinos são frequentemente relatados na literatura como contaminantes de ambientes aquáticos. Por isso, os processos oxidativos avançados (POAs) têm sido estudados como alternativa para o tratamento em meio aquoso. Os POAs consistem na oxidação de compostos orgânicos por radicais hidroxilas com alto poder oxidante. Diante desses aspectos, o presente trabalho tem como principal objetivo o estudo da degradação do metil parabeno (MeP) por processos Fenton, utilizando planejamento experimental e a análise dos modelos matemáticos, possibilitando a avaliação da influência das variáveis e determinando as melhores condições. As degradações de 300 mL de 100 mg L-1 de MeP com o processo Fenton foram realizadas em um reator de vidro onde as concentrações ótimas foram: 16 mg L-1 de Fe2+, 62 mg L-1 de H2O2, pH = 3, agitação constante e 30°C chegando a 100% de degradação em 20 minutos. Para o foto-Fenton, as degradações foram de 500 mL de 100 mg L-1 de MeP em um reator com lâmpada de mercúrio de 4 W , utilizando-se uma concentração de 4 mg L-1 de Fe2+ e 52 mg L-1 de H2O2, pH = 3, 30°C e agitação constante chegando a 100% de degradação em 16 minutos. Finalmente a degradação de 300 mL de 100 mg L-1 de MeP por eletro- Fenton foi realizada em um reator, com 4 mg L-1 de Fe2+, com densidade de corrente (j = 25 mA cm-2) para a produção de H2O2 com eletrodos ADE(cátodo), platina(ânodo), 0,05 mol L-1 de Na2SO4 como eletrólito suporte, pH = 3, sob agitação constante e 30°C chegando a 100% de degradação em 11 minutos. A eficiência da degradação de MeP foi monitorada por espectroscopia UV-VIS e cromatografia liquida de alta eficiência (CLAE) e, a mineralização, pelo monitoramento do carbono orgânico total (COT).Endocrine disruptors are frequently reported in the literature as contaminants of aquatic environments. Therefore, the advanced oxidation processes (AOPs) have been studied as an alternative to aqueous media treatments. AOPs involve the oxidation of organic compounds by hydroxyl radicals with high oxidation power. Considering these aspects, the aim of the present work is to study the methyl paraben (MeP) degradation by Fenton processes using experimental design and analysis of mathematical models, allowing the evaluation of the influence of variables and determining the best conditions. The degradation of 300 mL of 100 mg L-1 of MeP with Fenton process was performed in a glass reactor where the optimal concentrations were 16 mg L-1 of Fe2+, 62 mg L-1 of H2O2, pH = 3, constant stirring and T = 30°C, reaching 100 % degradation in 20 minutes . For the photo-Fenton degradations were 500 mL of 100 mg L-1 of MeP in a reactor with a mercury lamp with 4 W, using concentration of 4 mg L-1 of Fe2+, 52 mg L-1 of H2O2, pH = 3 , T = 30°C and constant stirring, reaching 100 % biodegradation in 16 minutes. Finally, the degradation of 300 mL of 100 mg L-1 of MeP by electro-Fenton was carried out in a reactor with 4 mg L-1 of Fe2+ with current density (j = 25 mA cm-2) for the production of H2O2 with ADE electrodes (cathode), platinum (anode), 0.05 mol L-1 Na2SO4 as supporting electrolyte, pH = 3, T = 30°C and constant stirring, to reaching 100 % degradation in 11 minutes. The degradation efficiency of MeP was monitored by UV- VIS spectroscopy and liquid chromatography (HPLC) and mineralization, by monitoring the total organic carbon (TOC).
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Škvařil, Michael. "Zjišťování trvanlivosti deskových modulárních prvků v různých prostředích." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409772.
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Within the theoretical part of the diploma thesis, a list of the main types of accelerated tests designed for the resistance of metal and polymer surface finishes. In the experimental part of diploma thesis, the rate of biological resistance of wood-based board materials is evaluated. Furthermore, the resistance of coating systems is assessed by means of accelerated tests. Resistance of modular building shells is primarily focused on degradation of coatings applied primarily on metal materials and wood materials. The tested coating systems analyze the influence of the materials and chemical base on the final weather resistance.
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Lavoie, Fernando Luiz. "Estudo do fenômeno de fissuramento sob tensão (stress cracking) em geomembranas de polietileno (PE) virgens e degradadas." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-18082006-133723/.
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Este trabalho apresenta resultados de ensaios de fissuramento sob tensão (FST) realizados em geomembranas de polietileno (PE) virgens e degradadas em laboratório. As geomembranas foram degradadas pela exposição à radiação ultravioleta, por envelhecimento térmico em estufa com circulação de ar, e pela compatibilidade química com soda cáustica e com vinhaça. Os resultados destes ensaios demonstram que os processos de degradação a que as geomembranas foram submetidas podem ser considerados catalisadores do fenômeno de FST, pois ocorreram reduções de resistência ao FST da ordem de 50 a 60%, com exceção para a amostra em compatibilidade química com vinhaça, que obteve aumento de 17% na resistência ao FSTThis work presents results of stress cracking tests (SC) accomplished in virgin and degraded polyethylene (PE) geomembranes at laboratory. Geomembranes were degraded by exposition to ultraviolet radiation, by thermal aging in oven with circulation of air, and by chemical compatibility with sodium hydroxide and with leachate of alcohol production. The results of these tests demonstrate that the degradation processes of the geomembranes were submitted can be considered catalysts of the phenomenon of SC, because they happened resistance reductions to stress crack resistance of the order from 50 to 60%, with exception for the sample in chemical compatibility with leachate of alcohol production, that had an increase of 17% in the stress crack resistance
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Fauré, Joël. "Etude de surfaces monocristallines de silicium par reflexion d'electrons : degradation par implantation d'ions argon, reorganisation par recuit." Toulouse 3, 1987. http://www.theses.fr/1987TOU30108.
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Etude de la degradation de la surface plane si(111) par implantation d'ions ar**(+) a temperature ambiante. Lorsque la dose d'ions implantes augmente, l'intensite des taches du diagramme de diffraction diminue progressivement et les marches atomiques, observees en microscopie electronique par reflexion, disparaissent. Lorsque l'energie incidente des ions ar**(+) augmente, la vitesse de degradation de la surface diminue. Apres disparition complete des marches atomiques, un recuit thermique "in situ" de quelques minutes a 575**(o)c permet de retrouver la topographie de la surface initiale. Le recuit provoque la desorption complete de l'argon implante et de retour en sites des atomes de la surface
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Dipold, Václav. "Sledování trvanlivosti výztuží z kompozitních materiálů s polymerní matricí a dlouhovláknovou výztuží." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240401.
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This thesis deals with monitoring the durability of FRP reinforcement in different types of environments which cause degradation. The theoretical part of the thesis describes reinforcing fibers, matrix materials, manufacturing technology of composite reinforcements by pultrusion and durability of FRP materials in environmental degradation. In the experimental part of this thesis was carried storing samples reinforcements in alkaline environment with various temperatures. As suitable were selected temperatures of 20 °C, 40 °C and 60 °C. Subsequently are described changes in physical properties of the reinforcements and tracking optical microscope.
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Židek, Ondřej. "Analýza účinku koncentrace slunečního záření na degradaci tepelných izolací ve skladbách plochých střech." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240331.
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The master´s thesis analyzes influence of direct and reflected solar radiation to heat strain and degradation of thermal insulation in the flat roof construction. In many building was a problem in a significant degradation of thermal insulation made from expanded polystyrene in the vicinity of glass surfaces. To determine the causes of this problem, it was necessary to study and test the properties of building materials and the physical nature of the effect of solar radiation on the building structure. In the introductory section lists the cases of buildings with degradation of thermal insulation and existing knowledge on this issue. The theoretical part describes the technical properties of thermal insulating materials used in the flat roof construction, nature and division of solar radiation, optical laws of light reflection and physical theory to explain the technical thermal behavior of building materials and structures. The last part describes a practical model and analyzing measured data in thermal stress in the flat roof construction. The practical part also determines the importance of different influences configuration structures using to dynamic simulations. At the end of the practical part they are validated theoretical knowledge obtained by analyzing data from a practical model.
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Baťa, David. "Analýza degradačních mechanismů oligobutadiénů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219213.
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This work deals with the studies of liquid oligobutadiens properties in AC electric field by dielectric relaxation spectroscopy method. The current issue in the diagnosis of oligomeric and polymeric materials during the activity of various degradation factors and options of their alleviation and suppression was studied. The existing apparatus is modified for monitoring possibilities of polymeric materials during the action of various degradation and operational factors. Effect of climatic factors are experimentally investigated, especially UV radiation and temperature on the course of the frequency dependence of complex permittivity components with respect to the different composition and length of the polymer chain.
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Zilli, Suzan Costa. "DETECÇÃO E DEGRADAÇÃO FOTOQUÍMICA DE ACRILAMIDA RESIDUAL EM ÁGUA PARA CONSUMO HUMANO." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/7896.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe acrylamide monomer is used mainly for the production of polyacrylamides, flocculation aids used in water supply systems. While its polymeric form does not pose health risks, the World Health Organization warns of the presence of residual acrylamide in flocculants, which would be responsible for releasing this contaminant in tap water. Acrylamide is considered as probably carcinogenic to humans, and has its standard for drinking water set at 0.5 μg L -1 in Brazil and in the United States, and 0.1 μg L-1 in Europe. Given the concern of the possibility of drinking water intake with the presence of acrylamide and lack of constant monitoring of this parameter, the objective of this study was to evaluate the application of photolytic processes for degradation of acrylamide and develop analytical methodology to quantify the acrylamide levels in trait, based on the Brazilian benchmark. The study was conducted following up the following steps: (I) development of bench photolytic reactor in Engineering Laboratory of Environment - LEMA, the Federal University of Santa Maria - UFSM; (II) conducting initial tests of direct photolysis (UV) photolysis combined with hydrogen peroxide (UV / H2O2) and use of hydrogen peroxide in the built reactor; (III) acrylamide analysis of development in the range of 0.5 to 5 mg L-1 via liquid chromatography with ultraviolet detection for monitoring the degradation in Environmental Analytical Chemistry Laboratory - LQAA, from the Chemistry Institute of the Federal University of Rio Grande do Sul - IQ-UFRGS; (IV) adequacy of degradation parameters and carrying out final tests of photolysis with lamp cooled reactor and analysis of results and preparation of the degradation kinetics, the LQAA; (V) defining parameters for most appropriate method of solid phase extraction to acrylamide; and (VI) adequacy of liquid chromatography via acrylamide analysis methodology of high efficiency with ultraviolet detection for a lower concentration range and validation of the method. The results demonstrated that acrylamide is slowly degraded via direct photolysis (k = 0.0143 mg L-1 min-1) and almost instantaneously when adding hydrogen peroxide (UV/H2O2), although alone peroxide has no effect. As for the method SPE according to the literature, active carbon is the most efficient for solid concentration of acrylamide. Thus, activated carbon was used cartridge for this step to give a satisfactory recovery of 72% acrylamide. The method developed via HPLC-UV showed good results as to the validation parameters of standard solutions. Same quality was not obtained when evaluated SPE-HPLC-UV conjunction with real fortified sample, probably due to the large number of possible interferences present in drinking water, coupled with the high solubility of acrylamide and difficulty of retention. The improvement of these analytical conditions should be required to make feasible the use of this method for the analysis of drinking water.
A acrilamida é um monômero utilizado principalmente para produção de poliacrilamidas, auxiliares de floculação empregadas em sistemas de abastecimento de água. Embora sua forma polimérica não represente riscos à saúde, a Organização Mundial da Saúde alerta para a presença de residuais de acrilamida nos floculantes, o que seria responsável por liberar esse contaminante na água tratada. Acrilamida é considerada como provavelmente carcinogênica para humanos, e tem seu padrão para água potável estabelecido em 0,5 μg L-1 no Brasil e nos Estados Unidos da América, e de 0,1 μg L-1 na Europa. Diante da preocupação da possibilidade de ingestão de água potável com a presença de acrilamida e da falta de monitoramento constante desse parâmetro, o objetivo desse trabalho foi avaliar a aplicação de processos fotolíticos para degradação da acrilamida e desenvolver metodologia analítica capaz de quantificar a acrilamida em níveis traço, baseado no valor de referência brasileiro. O estudo foi realizado seguindo-se as seguintes etapas: (I) desenvolvimento de reator fotolítico de bancada no Laboratório de Engenharia do Meio Ambiente - LEMA, na Universidade Federal de Santa Maria UFSM; (II) realização de testes iniciais de fotólise direta (UV), fotólise conjugada com peróxido de hidrogênio (UV/H2O2) e uso de peróxido de hidrogênio no reator construído; (III) desenvolvimento de análise de acrilamida na faixa de 0,5 a 5 mg L-1 via cromatografia a líquido com detecção por ultravioleta para acompanhamento da degradação, no Laboratório de Química Analítica Ambiental LQAA, do Instituto de Química da Universidade Federal do Rio Grande do Sul IQ-UFRGS; (IV) adequação dos parâmetros de degradação e realização dos testes finais de fotólise com reator de lâmpada resfriada, bem como análise dos resultados e avaliação da cinética de degradação, no LQAA; (V) definição de parâmetros para escolha do método mais adequado de extração em fase sólida para acrilamida; e (VI) adequação da metodologia de análise de acrilamida via cromatografia líquida de alta eficiência com detecção por ultravioleta para uma menor faixa de concentração e validação do método. Os resultados demonstraram que a acrilamida é lentamente degradada via fotólise direta (k = 0,0143 mg L-1 min-1) e, praticamente, de forma instantânea quando se adiciona peróxido de hidrogênio (UV/H2O2), embora, isoladamente, o peróxido não tenha qualquer efeito. Quanto ao método de EFS, de acordo com a literatura, o carvão ativo é o mais eficiente sólido para concentração de acrilamida. Assim, foi utilizado cartucho de carvão ativo para essa etapa, obtendo-se uma recuperação satisfatória de 72 % de acrilamida. O método desenvolvido via CLAE-UV demonstrou bons resultados quanto aos parâmetros de validação em soluções padrão. No entanto, os resultados não foram tão bons quando esta metodologia (EFS-CLAE-UV) foi aplicada à amostra real fortificada, provavelmente pela presença de grande quantidade de interferentes na água potável, aliada à grande solubilidade da acrilamida e dificuldade da sua retenção. A melhoria dessas condições analíticas deve ser pretendida a fim de tornar viável a utilização do método para análise de acrilamida em água potável.
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Rosecký, Pavel. "Analýza životnosti střešních PVC fólií." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392321.
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Roofing foils are known for several years as building material for roof hydro insulation but their life service is not yet fully known. This thesis is focused on problematics of life service of roofing foils. In theoretical part there is discribed structure of foils and impacts which assist degradation processes. Practical part modifies the methodology artificial aging which is simulated in QUV tester and Q-SUN XE3 tester lumber-rooms. The thesis is trying reach with the results to natural aging as close as possible. The testing captures attributes which are more prone to degradation.
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Papet, Gérard. "Etude cinetique du vieillissement radiochimique du polyethylene." Paris, ENSAM, 1987. http://www.theses.fr/1987ENAM0009.
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Etude de la radiolyse gamma du polyethylene basse densite dans l'air et a temperature ambiante. Les profils de distribution dans l'epaisseur de la concentration en carbonyles presentent une decroissance a une profondeur d'environ 180 microns. Determination des parametres cinetiques dans le cas ou la diffusion ne controle pas le vieillessement. Etude de modeles theoriques et de l'evolution des proprietes mecaniques pendant la degradation radiochimique
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Škarabelová, Lenka. "Degradace epoxidových pryskyřic s různými plnivy slunečním zářením." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377078.
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This master’s thesis is focused on the study of chemical and physical properties of dielectric materials with main focus on epoxy resins. It includes possible processes that can influence the properties of epoxy resins, both processes that improve polymer properties and processes that cause material degradation. Next part of the thesis is a description of diagnostic methods suitable for measurement of basic electrical quantities of material and design of a suitable method for measuring properties of epoxy resins with different additives, influencing the samples by solar radiation. At the end, the work includes an experiment dedicated to the degradation of epoxy resins with various additives by solar radiation and the evaluation of the experiment.
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Hamrat, Sonia. "Etude des échanges thermiques et conception d’un système de refroidissement pour le système de lecture du trajectographe SciFi de LHCb." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC104/document.
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Dans le cadre de l’évolution du plus grand accélérateur circulaire de particules « LHC », un important programme de mise à niveau sur l’ensemble des détecteurs qui le constitue a été lancé. Parmi eux, on retrouve la mise à niveau du détecteur LHCb qui comprend le remplacement complet de plusieurs sous-détecteurs. La fréquence de lecture élevée de 40MHz, sans précédent dans une expérience de physique des particules, et l’environnement de rayonnement sévère lié à l’augmentation de l’intensité du LHC, sont les principaux défis à relever par les nouveaux sous-détecteurs. Le travail présenté dans ce manuscrit, décrit une petite partie de l’évolution du détecteur LHCb. Le développement et la construction d’un nouveau trajectographe à grande échelle, basé sur une nouvelle technologie à fibres scintillantes «SciFi», lues avec des photomultiplicateurs au silicium «SiPM», est l’un des projets clés du programme de mise à niveau de LHCb. La première partie, consiste à étudier les échanges thermiques et à concevoir un système de refroidissement pour chaque Read-Out Box « ROB » qui contient deux cartes électroniques frontales « FE », et qui permettent de lire les données du détecteur. Ces dernières possèdent une dissipation thermique d’environ 110W.Pour assurer le bon fonctionnement des composants électroniques, il est obligatoire de mettre en place un refroidisseur. Des contraintes importantes sont prisent en compte dans cette étude, la première représente l’espace limité en regard du besoin du système de refroidissement, des interfaces électroniques et mécanique, la seconde concerne les SiPM. Reliés à l’électronique par des câbles flexibles, elles sont situées à proximité de l’électronique « FE » et leur température de fonctionnement doit être parfaitement réglée autour des -40°C. Des travaux de simulations numériques sur les logiciels FloTHERM et ANSYS ont été menés sur le banc expérimental réalisé au sein du laboratoire, et qui nous ont permis de déterminer la solution de refroidissement la mieux adaptée. Cette étude nous a aussi montré qu’il est plus que nécessaire d’intégrer des interfaces thermiques « IT» telles que des pâtes thermiques afin d’assurer un meilleur transfert de chaleur entre les composants électroniques et le refroidisseur. La deuxième partie, représente une étude approfondie sur les interfaces thermiques qui sont un point délicat de transfert de chaleur, car elles peuvent avoir plusieurs dizaines de pour cent de la résistance thermique globale. Pour garantir une utilisation adéquate et durable de ces matériaux, plusieurs paramètres ont été vérifiés, en particulier la dureté, la consistance (pas de production de graisse ou d’huile) et la conductivité thermique, grâce à un banc de mesures adapté d’après la méthode normalisé ASTM D5470, grâce auquel on a pu mesurer le flux de chaleur qui traverse l’échantillon d’interface thermique testé et qui est généré par une source chaude et un source froide qui sont montées aux extrémités de notre banc.Grâce à l’installation CHARME (CERN) et à la plate-forme PAVIRMA (Campus des Cézeaux), une série de mesure d’irradiations aux neutrons et aux rayons X sont également effectuées, correspondant à l’environnement dans lequel elles seront exposées dans l’expérience, d’un côté pour identifier les dégradations et changements possibles sur les résistances thermiques par l’analyse de l’impédance thermique, de l’autre pour identifier l’interface thermique qui convient le mieux à notre application et qui permet d’assurer un excellent échange thermique et donc un bon refroidissement de l’électronique frontale au sein du trajectographe du détecteur LHCbIn the context of the evolution of the biggest circular accelerator of particles «LHC», an important program of upgrade on all the detectors which establishes itself was thrown. Among them, we find the upgrade of the detector LHCb which includes the complete replacement of several sub-detectors. The frequency of high reading of 40MHz, an unprecedented in an experiment of physical appearance of particles, and the environment of severe radiation bound to the increase of the intensity of the LHC, are the main challenges by the new sub-detectors. The work presented in this manuscript, described as a small part of the evolution of the LHCb detector. The development and the construction of a new wide-scale tracker, based on a new technology with scintillating fiber «SciFi», read with photomultipliers to the silicon «SiPM», is one of the key projects of the LHCb upgrade program. The first part, consists in studying the thermal exchanges and designing a cooling system for every Read-Out Box «ROB» which contains two electronic front-end « FE », and which allow to read the data of the detector. The latter has a thermal dissipation about 110W. To ensure the smooth running of electronic components, it is compulsory to set up a cooler. Important constraints are taken into account in this study, the first one represents the space limited compared to the need for the cooling system, the electronic interfaces and mechanical, the second concerns the SiPM. Connected with the electronics by flexible cables, they are located near the electronics «FE» and their temperature of operation is perfectly settled around -40 ° C. Works of digital simulations on the software FloTHERM and ANSYS were led on the experimental bench realized within the laboratory, and which allowed us to determine the best adapted solution of cooling. This study also showed to us that he is more than necessity to integrate thermal interfaces «IT» such as thermal pastas to assure a better transfer of heat between electronic components and cooler. The second part, represents an in-depth study on the thermal interfaces which are a delicate point of transfer of heat, because they can have dozens percent of the global thermal resistance. To guarantee an adequate and sustainable use of these materials, several parameters were verified, in particular hardness, consistency (no production of fat or oil) and the thermal conductivity, thanks to a bench of measures adapted according to the method normalized ASTM D5470, with this bench we could measure the flow of heat through the tested thermal interface sample and which is generated by a hot source and a cold source that are mounted at the ends of our bench.With the installation CHARME (CERN) and PAVIRMA (Cézeaux), a series of measure of irradiations at the neutrons and the X-rays are also made, correspond-ing to the environment in which they will be exposed in the experience, on one side to identify the damages and the possible changes on the thermal resistances by the analysis of the thermal impedance, the other one to identify the thermal interface which suits best our application and which allows to assure an excellent thermal exchange and thus a good cooling of the frontal electronics within the trajectographe of the detector LHCb
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Venkataraman, Sunitha. "Systematic Analysis of the Small-Signal and Broadband Noise Performance of Highly Scaled Silicon-Based Field-Effect Transistors." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16232.
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The objective of this work is to provide a comprehensive analysis of the small-signal and broadband noise performance of highly scaled silicon-based field-effect transistors (FETs), and develop high-frequency noise models for robust radio frequency (RF) circuit design. An analytical RF noise model is developed and implemented for scaled Si-CMOS devices, using a direct extraction procedure based on the linear two-port noise theory.
This research also focuses on investigating the applicability of modern CMOS technologies for extreme environment electronics. A thorough analysis of the DC, small-signal AC, and broadband noise performance of 0.18 um and 130 nm Si-CMOS devices operating at cryogenic temperatures is presented. The room temperature RF noise model is extended to model the high-frequency noise performance of scaled MOSFETs at temperatures down to 77 K and 10 K. Significant performance enhancement at cryogenic temperatures is demonstrated, indicating the suitability of scaled CMOS technologies for low temperature electronics. The hot-carrier reliability of MOSFETs at cryogenic temperatures is investigated and the worst-case gate voltage stress condition is determined. The degradation due to hot-carrier-induced interface-state creation is identified as the dominant degradation mechanism at room temperature down to 77 K. The effect of high-energy proton radiation on the DC, AC, and RF noise performance of 130 nm CMOS devices is studied. The performance degradation is investigated up to an equivalent total dose of 1 Mrad, which represents the worst case condition for many earth-orbiting and planetary missions.
The geometric scaling of MOSFETs has been augmented by the introduction of novel FET designs, such as the Si/SiGe MODFETs. A comprehensive characterization and modeling of the small-signal and high-frequency noise performance of highly scaled Si/SiGe n-MODFETs is presented. The effect of gate shot noise is incorporated in the broadband noise model. SiGe MODFETs offer the potential for high-speed and low-voltage operation at high frequencies and hence are attractive devices for future RF and mixed-signal applications.
This work advances the state-of-the-art in the understanding and analysis of the RF performance of highly scaled Si-CMOS devices as well as emerging technologies, such as Si/SiGe MODFETs. The key contribution of this dissertation is to provide a robust framework for the systematic characterization, analysis and modeling of the small-signal and RF noise performance of scaled Si-MOSFETs and Si/SiGe MODFETs both for mainstream and extreme-environment applications.
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Olexová, Barbora. "Rozklady organických barviv metodami AOP." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216782.
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This diploma thesis is focused on the study of the influence of advanced oxidation processes on degradation of organic dyes. The field of AOP – very effective physically-chemical methods of wastewater treatment – includes application of strong oxidation agents, UV and ionizing radiation and electrical discharges. For this thesis, two of these methods were chosen – the application of oxidation agent (ozone) and UV radiation. Along with electrolysis, which is mentioned rather marginally in this thesis (it is the subject of the previous thesis), these phenomena are products of electrical discharge in water, where they participate in the processes of degradation in a different way. For all measurement series, two direct azo dyes were chosen as model substances – C.I. Direct Blue 106 and C.I. Direct Red 79. The ozonizer, in which either oxygen or synthetic or technical air were loaded as carrier gases, was used for degradation of dyes by ozone. The generated ozone was loaded into the bubbling vessel with dye solution of different initial concentration (10–130 mg.dm-3), which was followed by other bubbling vessel with KI solution for the next analytical determination of the amount of generated ozone. The other parameters changed were the gas flow (1–2 dm3.min-1), ozonizer output (minimal and maximal), type of dye, pH value of the solution (neutral or acid) and additional electrolyte (NaCl, Na2SO4 or any). The reactor for the study of the influence of UV radiation on degradation of dyes was an UV sterilizer into which the equivalent volume of dye solution was added. The possibilities of experimental settings were limited and only the type of dye, an additional electrolyte and pH value of the dye solution were adjusted (as in the case of ozone). Several series of samples were measured with various input conditions which more or less influenced the degradation of investigated dyes in this experiment. It was found that for both used methods the Direct Blue 106 dye was more degradable (with significantly better results for ozone than for UV radiation). The degradation of Direct Red 79 dye proceeded only by ozone treatment, in the case of the application of UV radiation no degradation occurred. By investigation of the influence of initial concentration of dye on its degradation, it was confirmed that with the initial concentration enhancement the final concentration rises as well, whereas in low concentrations (10–50 mg.dm-3) the initial concentration has no effect. The addition of an electrolyte had an accelerating effect on dye degradation in both methods (NaCl and also Na2SO4 showed similar results though the degradation proceeded in different ways). The addition of HCl accelerated the degradation only in the case of UV radiation; during the application of ozone the pH level of the system did not have any influence on the degradation. Oxygen and synthetic air had the strongest effect on ozone degradation (comparable results); in the case of technical air the final dye concentration was higher up to 30 %. The gas flow of 1.5 dm3.min-1 was stated as optimal with the ozonizer output 30 W (maximal). At minimal power the ozonizer produced very low amount of ozone.
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Ionescu, Adrian M. "Modèles et méthodes associes a la caractérisation électrique du tmos : application aux technologies SOI." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0009.
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Les modeles et les methodes associees a la caracterisation electrique du tmos et particulierement, leur application aux technologies soi constituent l'objet de ce travail. Le premier chapitre est consacre a l'analyse du fonctionnement electrique du tmos/silicium massif ; nous proposons une expression unifiee en inversion faible, moderee et forte, pour le courant de drain, en regime lineaire, et son application a l'extraction de la tension de seuil. On analyse aussi l'influence des polarisations sur la sensibilite du tmos utilise comme capteur de champ magnetique. Le developpement theorique et experimental de la technique du pseudo-transistor mos, pour l'evaluation des materiaux soi sur plaquette, est donne dans le deuxieme chapitre. On y presente : la validation d'une nouvelle methode pour la determination de la duree de vie de generation dans les materiaux soi, l'etude de l'influence des resistances serie et des contacts schottky, la methode 3-pointes et l'evaluation du materiau unibond. Le troisieme chapitre est dedie a l'etude du tmos en technologie soi : on analyse le regime transitoire du courant de drain en inversion faible associe a la technique de zerbst et on effectue une etude systematique de la degradation des tmos/simox par irradiation gamma a de fortes doses (>1mrad).