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Xia, Chun, and Chun Xia. "Concentration Quenching Effect in Rare-earth Doped Glasses." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/624145.
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Concentration quenching effect in ytterbium (Yb) and neodymium (Nd) doped phosphate glasses, thulium (Tm) doped germanate glass, and praseodymium (Pr) doped tellurite glass were studied. The fluorescence and lifetime of these rare-earth doped glasses with different concentrations were measured. Ion pair and clustering are included in the model to explain the quenching effect occurring in highly doped glasses. This study will help us in designing and fabricating high unit gain optical fibers.
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COELHO, DANIEL MASSARI DE SOUZA. "EFFECT OF THE AUSTENITIZATION TEMPERATURE ON THE QUENCHING AND PARTITIONING PROCESS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12177@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>O processo de Têmpera e Partição (T&P) possibilita a
produção de aços com frações controladas de austenita
retida, a partir do enriquecimento da austenita pela
partição de carbono da martensita sem a precipitação de
carbonetos. A austenita retida proporciona o efeito TRIP
(plasticidade induzida por transformação), que confere ao
material uma deformação uniforme e uma melhor absorção de
energia durante o impacto. Os aços produzidos por este
processo atendem principalmente às necessidades da indústria
automobilística, que busca aços com melhores propriedades
para a diminuição de peso e aumento da
segurança dos automóveis. Nesta dissertação, ligas de aço
com diferentes composições e tamanhos de grão foram
produzidos pelo processo de Têmpera e Partição e a fração de
austenita retida foi medida por difração de raios-X. As
ligas também foram caracterizadas por nanoindentação,
microscopia ótica e microscopia eletrônica de varredura. As
amostras estudadas foram produzidas com uma austenitização
completa a 930°C, realizada para promover um aumento
no tamanho de grão, e os resultados foram comparados com
amostras estudadas anteriormente com temperatura de
austenitização de 890°C. Os resultados obtidos
indicaram um aumento da fração de austenita retida com o
aumento do grão austenítico original. Estes resultados foram
interpretados com base no modelo teórico desenvolvido para o
processo T&P.<br>The Quenching and Partitioning (Q&P) process allows the
production of steels with controlled fractions of retained
austenite from the enrichment of the austenite by carbon
partitioning from the martensite without carbide
precipitation. The retained austenite is responsible for the
TRIP effect (transformation induced plasticity), which
enhances the material behavior providing a uniform strain
and a better energy absorption during impact. Steels
produced by this process match the requirements of the
automotive industry, which looks for weight reduction and
safety improvements in cars. In the present dissertation,
steels with different compositions and grain sizes were
produced by the Quenching and Partition process and their
retained austenite fraction was measured by x-ray
diffraction. The steels were also characterized by
nanoindentation, optical microscopy and scanning electron
microscopy. The specimens studied were produced by a
complete austenitization at 930°C, to promote an increase in
the austenitic grain size, and the results were compared
with previously studied specimens produced by a complete
austenitization at 890°C. The experimental results indicate
an increase of austenite fraction with an increase in grain
size of the original austenite. These results were analyzed
based on the theoretical model develop for the Q&P process.
3
Lee, Lin. "The effect of flow rate, spray distance and concentration of polymer quenchant on spray quenching performance of CHTE and IVF probes." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-050205-151345/unrestricted/LinLeeThesis.pdf.
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Li, Yu. "Effect of aluminium and vanadium on the microstructure and properties of microalloyed steels." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366804.
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Xu, Rixin. "Finite Element Modeling and Simulation on the Quenching Effect for Spur Gear Design Optimization." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1217868964.
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Grisenti, David L. "The effect of bimolecular quenching reactions on energy transfer processes in oligometallic metal to ligand charge transfer excited states." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1495960661&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Borasi, Luciano. "Investigation of the Effect of Different “Q&P” Parameters on the Mechanical Properties of AHSS." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70060.
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In the present study, the influence of the quenching temperature and partitioning conditions (temperature and time) have been investigated on a 0.6%C-1.2%Mn-1.6%Si-1.75%Cr alloy. Maps of hardness, impact toughness and amount of retained austenite have been developed for three quenching temperatures as a function of partitioning temperature and partitioning time. Results demonstrate that, in this material, the carbon depletion of the martensite and the stabilization of austenite can be achieved significantly faster at high partitioning temperatures, promoting higher retained austenite fractions, lower hardness, and maximizing the energy absorbed in a Charpy V‑Notch test. In addition, the effect of the partitioning time was also analysed, presenting different behaviour at high and low partitioning temperatures. Whereas an increment of time at high partitioning temperatures (>400 ºC) leads to an austenite consumption, at low partitioning temperatures it is effective to retain a higher amount of austenite. Furthermore, tensile properties are shown to be better than in conventional alloys utilized in industry. Whilst, for example, the AISI 52100 alloy achieves 2 GPa of tensile strength and 1‑2% of fracture deformation, in the present study the notable combination of 2.5 GPa of tensile strength and 5.7 % of fracture deformation was achieved in samples quenched until room temperature. Untempered martensite transformed during final cooling in samples quenched until higher temperatures was shown to be detrimental for tensile properties. A comparison between the Q&P process and the austempering process on this alloy has been carried out. Results reveal that the quenching and partitioning heat treatment is presented as a promising alternative to reach higher hardness (>700 HV) and similar specific wear rates in dry conditions performing a shorter heat treatment. Finally, a complementary study about the effect of micro-segregation on the Q&P process and an optimization method to minimize the inhomogeneity of the structure by a correct selection of the quenching temperature were established.
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Adeyemo, Adedayo Oluwagbemiga David. "Modulation of apoptosis and its regulatory proteins in colorectal cancer cells : effect of oxidant quenching and NSAIDs on (5 Fu) chemotherapy-induced toxicity." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404584.
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Huyghe, Pierre. "ON THE RELATIONSHIP BETWEEN MICROSTRUCTURE DEVELOPMENT AND MECHANICAL PROPERTIES IN Q&P STEELS." Doctoral thesis, Universite Libre de Bruxelles, 2018. https://dipot.ulb.ac.be/dspace/bitstream/2013/278740/5/contratPH.pdf.
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The Quenching and Partitioning (Q&P) heat treatment has been proposed in the early 2000s to produce cold-rolled sheets combining high-strength and formability for the automotive market. Q&P consists, first, of an interrupted quench between the martensite-start temperature (Ms) and the martensite-finish temperature (Mf) from intercritical annealing or full austenitization in order to form controlled fractions of martensite. This is followed by a partitioning step in order to stabilize the untransformed austenite through carbon enrichment. In order to maximize the carbon transfer from martensite to austenite, the use of specific alloying elements and the design of appropriate Q&P parameters are required to eliminate or minimize competing phenomena such as carbide formation and austenite decomposition. The final quenched and partitioned microstructure, using full austenitization, ideally consists of carbon-depleted lath martensite and significant fractions of retained austenite providing an improved combination of strength and ductility. Hence, the transformation of retained austenite upon straining at room temperature (TRIP effect) provides supplementary work-hardening and eventually improves the ductility. In the present work, Quenching and Partitioning (Q & P) heat treatments were carried out in a quench dilatometeron a 0.2 wt% carbon steel. The microstructure evolution of the Q & P steels was characterized usingdilatometry, SEM, EBSD and XRD. The martensitic transformation profile was analyzed in order to estimate thefraction of martensite formed at a given temperature below the martensite start temperature Ms. Q & P wasshown to be an effective way to stabilize retained austenite at room temperature. However, the measuredaustenite fractions after Q & P treatments showed significant differences when compared to the calculated valuesconsidering ideal partitioning conditions. Indeed, the measured austenite fractions were found to be less sensitiveto the quench temperature and were never larger than the ideal predicted maximum fraction. Competitivereactions such as austenite decomposition into bainite and carbide precipitation were found to occur in thepresent work.Furthermore, a broad range of mechanical properties was obtained when varying the quenching temperaturesand partitioning times. The direct contributions between Q & P microstructural constituents -such as retainedaustenite as well as tempered/fresh martensite- and resulting mechanical properties were scrutinized. This wascritically discussed and compared to quenching and austempering (QAT) which is a more conventional processingroute of stabilizing retained austenite at room temperature. Finally, Q & P steels were shown to exhibit aninteresting balance between strength and ductility. The achievement of this interesting combination of mechanicalproperties was reached for much shorter processing times compared to QAT steels.<br>Doctorat en Sciences de l'ingénieur et technologie<br>info:eu-repo/semantics/nonPublished
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Kaijalainen, A. (Antti). "Effect of microstructure on the mechanical properties and bendability of direct-quenched ultrahigh-strength steels." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526213491.
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Abstract The effect of austenite pancaking in the non-recrystallisation regime on microstructure and mechanical properties, especially bendability, was investigated in direct-quenched ultrahigh-strength strip steels with martensitic-bainitic microstructures. Lowering the finishing rolling temperature (FRT) increased total reduction in the non-recrystallisation region (R tot). Niobium microalloying increased Rtot while variations in C, Mn and Mo did not affect Rtot to the same extent as Nb. A decrease in the FRT increased the incidence of softer microstructures such as ferrite and granular bainite in the subsurface layers. The microstructures at the centreline were comprised of auto-tempered martensite with some bainite. An increase in Rtot strengthens the intensities of the ~{554}<225>α and ~{112}<110>α texture components at the centreline and the components ~{112}<111>α and ~{110}<112>α - {110}<111>α at the strip subsurface. Bendability is poorer with the bend axis perpendicular rather than parallel to the rolling direction (RD) and is further impaired with increasing hardness below the sheet surface. An intense ~{112}<111>α shear texture combined with upper bainite containing MA islands in the subsurface region is shown to be detrimental to bendability when the bend axis is perpendicular to the RD. This anisotropy of bendability can be explained by the appearance of geometric softening in grain clusters belonging to this texture component when the bend axis is perpendicular to the RD. Shear localisation is prevented, however, by the presence of a sufficiently thick subsurface microstructure having adequate work hardening capacity, i.e., ferrite + granular bainite rather than ferrite + upper bainite. The strain required to initiate strain localisation can be increased and good bendability thereby achieved—even in the presence of detrimental texture components—by ensuring the presence of a sufficiently soft subsurface layer extending to a depth of approximately 5% of the total sheet thickness. The above beneficial microstructures can be obtained and good bendability ensured in direct-quenched strip steel with a yield stress above 900 MPa together with good impact toughness, provided a suitable combination of chemical composition and processing parameters is selected and sufficient attention is paid to steelmaking operations to obtain a proper inclusion structure<br>Tiivistelmä Austeniitin muokkauksen vaikutusta mikrorakenteeseen ja mekaanisiin ominaisuuksiin, erityisesti särmättävyyteen, tutkittiin suorasammutetuilla martensiittis-bainiittisilla suurlujuusnauhateräksillä. Kuumavalssauksen lopetuslämpötilan lasku kasvatti austeniitin kokonaisreduktiota ei-rekristallisaatioalueella. Mikroseostus niobilla kasvatti myös kokonaisreduktiota, kun taasen muutokset C-, Mn- ja Mo -pitoisuuksissa eivät vaikuttaneet yhtä voimakkaasti. Valssauksen lopetuslämpötilan lasku kasvatti pehmeämpien mikrorakenteiden, kuten ferriitin ja granulaarisen bainiitin, määrää nauhan pintakerroksessa. Terästen keskilinjan mikrorakenteet koostuivat pääasiassa itsepäässeestä martensiitista sekä pienestä määrästä bainiittia. Kokonaisreduktion kasvu voimisti ~{554}<225>α - ja ~{112}<110>α -tekstuurikomponentteja keskilinjalla sekä ~{112}<111>α- ja ~{110}<112>α - {110}<111>α -komponentteja nauhan pintakerroksessa. Särmättävyys oli huonompi särmän ollessa poikittain valssaussuuntaan nähden kuin pitkittäin. Pintakerroksen kovuuden kasvu heikensi särmättävyyttä. Pintakerroksen voimakas ~{112}<111>α -leikkaustekstuuri, yläbainiitin ja MA-saarekkeiden läsnä ollessa, osoittautui haitalliseksi särmän ollessa poikittain valssaussuuntaan nähden. Särmättävyyden anisotrooppisuus voidaan selittää geometrisella pehmenemisellä rakeissa, joissa kyseinen tekstuurikomponentti on voimakas. Leikkausmyötymän paikallistuminen estyy, kun pinnassa on riittävän paksu hyvän muokkauslujittumiskyvyn omaava kerros, mikä sisältää esim. ferriittiä ja granulaarista bainiittia, mutta ei ferriittiä ja yläbainiittia. Särmättävyys osoittautui pysyvän hyvänä huolimatta haitallisesta tekstuurikomponentista, kun pehmeä pintakerros ulottui noin 5 % syvyydelle levyn paksuudesta. Edellä mainitut mikrorakenteet ja hyvä särmättävyys voidaan saavuttaa suorasammutetuilla yli 900 MPa myötölujuuden nauhateräksillä yhdessä hyvän iskusitkeyden kanssa, kunhan valitaan sopiva kemiallisen koostumuksen ja valmistusparametrien yhdistelmä sekä kiinnitetään huomiota teräksen sulkeumapuhtauteen
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Aksoy, Fuat Yigit. "Interaction of Metal Nanoparticles with Fluorophores and Their Effect on Fluorescence." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1240302257150-32578.
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Metal nanoparticles have recently gained popularity in many research areas due to their nanosize-related properties. Depending on the size of the metal nanoparticle, their mode of interaction with electromagnetic radiation and the outcome of this interaction vary; in turn the effect exerted on a protein which is conjugated to a nanoparticle varies, because different sized nanoparticles demonstrate different modes of energy transfer with electromagnetic radiation and molecules conjugated to them. Very small cluster with sizes around 1 – 1.2 nm tend to get excited by incident light and emit fluorescence, whereas larger nanoparticles absorb the incoming light very strongly due to their LSPR. In this study we observed the outcomes of the interaction between two types of nanoparticles, namely gold and gold/silver alloyed nanoparticles with the fluorescence emission of two fluorophores, namely eGFP and rPhiYFP; and demonstrated a bioassay where the fluorescence modulation by gold nanoparticles can be used as the sensing strategy. Lastly, we demonstrated the potential of autofluorescent gold nanoparticles as intracellular reporters.
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Melado, André Caetano. "Ferros fundidos nodulares de alta resistência obtidos por tratamento térmico de têmpera e partição: microestrutura e comportamento mecânico." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-16072018-134449/.
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A aplicação do novo conceito de tratamento térmico, chamado de têmpera e partição (Q&P), desenvolvido para a obtenção de aços da terceira geração da classe AHSS (Advanced high strengh steel ou aços avançados de alta resistência), mostra-se uma alternativa para o processamento de ferros fundidos nodulares com alta resistência mecânica. No processo Q&P, o carbono presente na martensita supersaturada, formada na etapa de têmpera, é utilizado para estabilizar a austenita não transformada durante a etapa de partição, mantendo-a estável na temperatura ambiente. Essa rota de tratamento térmico consiste em realizar uma têmpera no material (após uma etapa prévia de austenitização) numa faixa de temperatura entre o Ms e Mf (temperatura de início e fim da transformação martensítica, respectivamente), seguido de um reaquecimento e manutenção a uma temperatura acima do Ms (etapa isotérmica de partição) com o objetivo de que o carbono migre da martensita supersaturada para a austenita remanescente promovendo sua estabilização. Essa partição do carbono só é possível caso a precipitação da cementita seja suprimida, e isso é conseguido com a presença de elementos de liga, como o Si e/ou Al. Neste trabalho foi feito um estudo sobre as características microestruturais e mecânicas de um ferro fundido nodular (3,47%C; 2,47%Si; 0,2%Mn) submetido ao tratamento térmico de têmpera e partição, o qual foi denominado neste trabalho como, Q&PDI (Quenched and Partitioned Ductile Iron ou Ferro Fundido Nodular Temperado e Particionado). Para isso foi realizada uma austenitização plena nas amostras, a 880°C, por duas horas, seguida de uma têmpera em óleo pré-aquecido nas temperaturas de 140 e 170°C. A etapa de partição foi feita nas temperaturas de 300, 375 e 450°C, com intervalos de tempo variando de 5 a 120 minutos. A caracterização microestrutural foi realizada através de microscopia ótica, microscopia eletrônica de varredura e EBSD. A técnica de difração de raios-X foi empregada para quantificar a fração volumétrica e o teor de carbono na austenita retida. Ensaios de dilatometria, difração de raios-X \"in situ\" e nanoindentação foram empregados para auxiliar na análise das transformações de fases que ocorreram na etapa de partição, como a transformação bainítica e a precipitação de carbonetos de transição nas placas de martensita. A caracterização mecânica foi feita através de ensaios de tração, impacto, dureza, nanoindentação, tenacidade à fratura e resistência à fadiga. Ensaios de compressão auxiliaram na análise da transformação martensítica induzida por deformação. Os resultados obtidos mostraram que é possível obter ferros fundidos nodulares com alta resistência mecânica (limite de resistência >1450 MPa), com consideráveis ductilidade (de até 9%) e energia absorvida sob impacto (de até 81 J), bem como tenacidades à fratura de 55 MPa.m1/2 e limites de fadiga de 550 MPa. Este comportamento é proporcionado por uma microestrutura singular, constituída por uma dispersão homogênea de placas de martensita numa matriz de ausferrita bastante refinada, com consideráveis frações volumétricas de austenita retida (max. 23%).<br>Quenching and partitioning (Q & P), a new heat treatment concept developed to obtain third generation AHSS (Advanced High Strength Steel), is an alternative for processing of nodular cast irons in order to obtain high mechanical strength. In the Q & P process, the carbon present in the supersaturated martensite formed in the quenching step diffuses towards the untransformed austenite during the partition step, keeping it stable at room temperature. This heat treatment route consists of quenching the material (after a previous step of austenitization) in a temperature range between Ms and Mf (beginning and end temperature of the martensitic transformation, respectively), followed by reheating and maintenance at a temperature above the Ms (isothermal stage of partition) allowing the carbon to migrate from the supersaturated martensite to the remaining austenite, promoting its stabilization. This partition of carbon is only possible if precipitation of cementite is suppressed; this is achieved adding alloying elements such as Si and/or Al. In this work a study was made on the microstructural and mechanical characteristics of a ductile iron (3.47%C; 2.47%Si; 0.2%Mn), submitted to a Q&P heat treatment, in this work named Q & PDI (Quenched and Partitioned Ductile Iron). A full sample austenitization was carried out at 880 ° C for two hours, followed by a pre-heated oil quanching at temperatures of 140 and 170 ° C. The partitioning step was at temperatures of 300, 375 and 450Â ° C, with time intervals ranging from 5 to 120 minutes. Microstructural characterization was performed through optical microscopy, scanning electron microscopy and EBSD. The X-ray diffraction technique was used to quantify the volumetric fraction and the carbon content in the retained austenite. Dilatometry, X-ray diffraction \"in situ\" and nanoindentation were also used to aid in the analysis of the phase transformations that occurred in the partitioning stage, such as the bainitic transformation and the precipitation of transition carbides in the martensite plates. Mechanical characterization was performed through tensile, impact, hardness, nanoindentation, fracture toughness and fatigue strength tests. Compression tests aided in the analysis of the deformation induced martensitic transformation. The results showed that it is possible to obtain nodular cast irons with high mechanical strength (resistance limit> 1450 MPa), with considerable ductility (up to 9%) and energy absorbed under impact (up to 81 J), as well as fracture toughness of 55 MPa.m -1 / 2 and fatigue limits of 550 Mpa. This behavior is provided by a unique microstructure, consisting of a homogeneous dispersion of martensite plates in a very refined ausferrite matrix, with considerable volumetric fractions of retained austenite (max. 23%).
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Wickremasinghe, Niranjala D. "Optical Properties of Organic Films, Multilayers and Plasmonic Metal-organic Waveguides Fabricated by Organic Molecular Beam Deposition." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439307144.
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Gelloz, Bernard. "Contribution à l'étude des mécanismes de conduction du silicium poreux : application aux phénomènes de luminescence." Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10153.
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Ce travail est consacre aux mecanismes de conduction du silicium poreux en contact avec un electrolyte liquide conducteur, ainsi qu'a l'etude du comportement de la luminescence sous polarisation. La premiere partie presente les principales caracteristiques de la luminescence du silicium poreux ainsi que les differents modeles qui ont ete proposes pour en expliquer les mecanismes. La deuxieme partie est consacree a la description des methodes experimentales utilisees pour la fabrication des couches poreuses et l'etude de leurs proprietes de photo et d'electroluminescence. Dans une troisieme partie, les mecanismes de conduction du silicium poreux ont ete etudies. Il a ete montre que ces derniers etaient determines par les flux d'ions et d'electrons en provenance de l'electrolyte et du substrat de silicium ainsi que par la cinetique d'echange de charges a l'interface silicium-electrolyte. Un modele quantitatif a ete developpe qui rend bien compte de l'etat de peuplement de la couche poreuse en porteurs libres et permet d'interpreter la presence ou l'absence d'electroluminescence. Une quatrieme partie est consacree aux phenomenes d'extinction de la luminescence sous l'action d'une polarisation electrique. Elle a permis de degager des arguments decisifs en faveur d'un mecanisme base sur l'effet auger. Enfin, dans une derniere partie situee en annexe, un certain nombre de resultats experimentaux complementaires sont presentes. Il s'agit d'une part du comportement electrochimique d'electrodes de silicium poreux dont les pores ont ete tapisses de germanium, et d'autre part de l'etude de l'influence des traitements thermiques sur la luminescence du silicium poreux.
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Rondeau, Darrell K. "The effects of part orientation and fluid flow on heat transfer around a cylinder." Link to electronic thesis, 2004. http://www.wpi.edu/Pubs/ETD/Available/etd-0512104-174214/.
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Cai, Lezhen. "Mechanisms and salt effects in photoredox and quenching processes involving cobalt(III) complexes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21925.pdf.
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Guo, Guannan. "Aluminum microstructure evolution and effects on mechanical properties in quenching and aging process." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/334.
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"High strength aluminum alloys are recently widely used in aircraft, automobile and construction industry fields. Typical T6 heat treatment process can be applied to improve the heat treatable aluminum alloy in order to facilitate the formation of prime strengthening precipitate phases. Critical steps in T6 heat treatment process include solution treatment, quenching and aging. Due to high thermal gradients in quenching process and aging process, large thermal stress will remain in the matrix and may bring unexpected deformation or distortion in further machining. Therefore, in order to predict the thermal stress effects, constitutive model and precipitate hardening model are needed to simulate the mechanical properties of alloy. In this dissertation, an optimized constitutive model, which is used to describe the mechanical behavior during quenching and intermediate period of quenching and aging process, was given based on constitutive models with Zenor-Holloman parameter. Modification for constitutive model is based on the microstructure model, which is developed for the quenching and aging processes. Quench factor analysis method was applied to describe the microstructure evolution and volume fraction of primary precipitate phases during quenching process. Some experimental phenomena are discussed and explained by precipitate distributions. Classical precipitate hardening models were reviewed and two models were selected for Al-Cu-Mn alloy aging treatment. Thermal growth model and Euler algorithm were used to improve the accuracy and the selected precipitate hardening models were validated by yield stress and microstructure observations of Al-Cu-Mn aging response experiments."
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Dorcéna, Cassandre Jenny. "Effects of Metallic Nanoalloys on Dye Fluorescence." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35057.
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Metallic nanoparticles (NPs) are exploited for their ability to interact with organic
compounds and to increase significantly the fluorescence intensity and the photostability
of many fluorescent dye molecules. Metal enhanced fluorescence (MEF) is therefore
widely investigated for biosensing applications. When used in immunoassays, silver
island films (SIFs) could augment the fluorescence intensity of fluorescein by a factor of
seventeen; SIFs were also able to double or triple the emission intensity of cyanine dyes
which are commonly used in (deoxyribonucleic acid) DNA microarrays. The emission
intensity of indocyanine green â widely used as a contrast agent in medical imaging â
was about twenty times higher in the proximity of SIFs.
This enhancement phenomenon - due to the surface plasmon polaritons associated
with the metallic NPs â can be explained by energy transfer from the metal NPs to the
fluorescent dye molecules or by a modified local electromagnetic field experienced by
the fluorophores in the vicinity of metal surfaces.
Our research focused on the optical characterization of colloidal gold-silver alloy
NPs containing different ratios of gold and silver (Au1.00-Ag0.00, Au0.75-Ag0.25, Au0.50-
Ag0.50, and Au0.25-Ag0.75), as well as their interaction with three fluorophores: rose
bengal, rhodamine B, and fluorescein sodium. Depending upon the dye quantum yield
and its concentration in solution, enhancement or quenching of fluorescence was
obtained. Thus, a three to five times increase in fluorescence intensity was observed in a
2.0 mM solution of rose bengal with all nanoalloys, a slight enhancement of fluorescence
(1.2 â 1.6 times) was noticed in a 0.13 mM solution of rhodamine B with all four types of
NPs, and fluorescence quenching occurred in all the fluorescein-NP solutions regardless
of the dye concentration.<br>Master of Science
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Turcios, Marco Antonio. "Effects of cold wall quenching on unburned hydrocarbon emissions from a natural gas HPDI engine." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/38308.
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The quenching of hydrocarbon flames on cold surfaces is considered to be a potential source of unburned hydrocarbon (UHC) emissions from internal combustion engines, but its contribution to emissions has been difficult to determine due to the strong coupling between physics, chemistry and flame/wall geometry. This is particularly problematic for high pressure direct injection (HPDI) engines where high pressures, inhomogeneous mixtures and complex piston geometry are present.
In this work, a computational model is implemented to determine the distance at which hydrocarbon flames quench on cold walls during numerical simulation. This model accounts for variable pressure, temperature, gas mixture and the geometry conditions. The model presented in this work is an extension of the experimental work done by Boust et. al. with stoichiometric premixed flames at low pressures. The validation of this model for high pressure and diffusion flames is presented and shows that the correct trends in heat flux and order of magnitude of quench distance are observed. This model is further refined for engine simulation and enhanced by a two-zone mass diffusion model to account for post-quench oxidation of boundary fuel.
A selection of engine cases are simulated for a variety of different conditions to determine the spatial distribution and temporal evolution of unburned fuel cold surfaces. It was found that wall quenching on the piston contributes up to 50% of the total UHC during the combustion cycle, the majority of which is oxidized during the expansion stroke; the final contribution is at most 10% but frequently near or less than 1%. As the injection pressure was increased, quenching on the piston surface became more extensive, through the quenching thickness itself decreased. UHC from wall quenching occurs more readily for higher load conditions due to the richer mixtures and incomplete mixing. Altered engine timing introduced coupled effects of changed flame/wall interaction and combustion characteristics. The data obtained from the model can be used to evaluate attempts to reduce UHC by changing combustion chamber geometry.
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Theron, Maritha. "Quenching and tempering effects on Rheo-cast F357 aluminium alloy during Nd: YAG laser welding." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/26148.
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Al-Si-Mg casting alloys are being used in automotive applications, aerospace applications and other applications requiring heat-treatable permanent mould castings that combine good weldability with high strength and toughness (ASM). These casting alloys are also known for their excellent castability, corrosion resistance and, in particular, .a range of mechanical properties in the heattreated condition. A357 aluminum alloy has been extensively used for semi-solid processing for more than three decades, and a large amount of components like fuel rails, engine mounts, engine brackets and suspension parts have been produced. This alloy is also included in the Statement for Work between the Council for Scientific and Industrial Research (CSIR) and Boeing Co, USA. F357, a hypo-eutectic aluminium alloy, Al-7%Si-0.6%Mg without beryllium, was processed with CSIR-Rheo technology to the Semi-Solid Metal (SSM) state and cast in plates with a 50 Ton High Pressure Die Casting machine. The castings were either left in the as-cast (F) condition or subjected to T4, T4+ or T6 heat treatments prior to laser welding. Welding of aluminium alloys poses many problems like porosity, loss of alloying elements, poor bead geometry and softening of the heat affected zone. Laser welding is however widely used in industrial production owing to the advantages such as low heat input, high welding speed and high production rate. Due to these unique advantages, the potential of autogenous Nd: Y AG laser welding as manufacturing process for this cast aluminium alloy was evaluated. A welding operating window was established and the optimum parameters were found to be a laser power of 3.8 kW at the workpiece and a welding speed of 4 m/min with a twin spot laser light configuration. These laser welding parameters were applied for the welding of the heat treated plates and resulted in very low weld joint porosity and almost no loss of alloying elements. The mechanical properties of age-hardenable Al-Si-Mg alloys are dependent on the rate at which the alloy is cooled after the solution heat treatment Because of the high cooling rate during laser welding, the possibility of producing weld seams through deep penetration laser welding, with mechanical properties matching those of the T6 temper condition, but without a post-weld solid solution heat treatment, was investigated. The quench rate after laser welding was measured and compared well with that measured after solution treatment. The resulting mechanical properties of F357 aluminium welded in the T4 condition and only artificially aged after welding (T4+ condition), compares very well with the T6 base material properties. The strengthening mechanisms obtained during laser welding and the different heat treatments were studied by means of transmission electron microscopy (TEM) and are consistent with the expected precipitation hardening processes in Al-Si-Mg alloys. The quench sensitivity of SSM F357 aluminium alloy is thus sufficiently low to obtain such an increase in strength values during laser welding, that no postweld solution heat treatment is necessary to achieve mechanical properties to the T6 performance specification.
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Perkins, Thomas Edward James. "The effects of electronic quenching on the collision dynamics of OH(A) with Kr and Xe." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:5998e249-35ff-4d05-9c13-9b65d59b11d9.
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This thesis presents an experimental and theoretical study of the collision dynamics of OH(A<sup>2</sup>Σ<sup>+</sup>) with Kr and Xe. These two systems both exhibit a significant degree of electronically non-adiabatic behaviour, and a particular emphasis of the work presented here is to characterise the competition and interplay between electronic quenching on the one hand, and electronically adiabatic collisional processes on the other. Quenching takes place close to the bottom of the deepest potential well for both systems. In collisions that remain in the excited electronic state, this same region of the potential is also largely responsible for rotational energy transfer (RET) and the collisional depolarisation of angular momentum. Therefore, the direct competition between these processes suppresses the cross-sections for RET and collisional depolarisation from their expected value in the absence of quenching. To investigate this, experiments were carried out to measure cross-sections for the collisional transfer of electronic, vibrational and rotational energy in OH(A, v=0,1) + Kr and OH(A, v=0) + Xe. In addition, measurements were made of the j-j' correlation -- that is, the relationship between the angular momentum of the OH radical before and after a collision -- in collisions with Kr and Xe, using the experimental technique of Zeeman quantum beat spectroscopy. Collisions with both Kr and Xe tend to effectively depolarise the angular momentum of the OH radical, due to the very anisotropic character of the potential on which the process occurs. Electronic quenching, which plays an essential role in both systems, is more prevalent with xenon as the crossing to the ground state potential is located in a more accessible location. These experimental results were compared with single surface quasi-classical trajectory (QCT) calculations, where the overestimate of rotational energy transfer or collisional depolarisation helps to elucidate the degree to which the presence of quenching suppresses these processes. Surface hopping QCT was then used to account for non-adiabatic transitions in the theory, which led to an improvement in agreement with experiment. However, standard surface hopping QCT theory failed to account for the full extent of quenching in these two systems. A major focus of this work is therefore on the development of an extension to standard surface hopping QCT theory to incorporate rovibronic couplings. In non-linear configurations, the excited state of the OH + Kr, Xe systems has A' symmetry, while the ground state is split into symmetric (A') and antisymmetric (A'') components. For these symmetry reasons, coupling is restricted to the two states of the same symmetry, however a rotation of the correct (A'') symmetry can induce transitions to the A'' state too. Inclusion of all three electronic states, and the relevant couplings between them, is found to be crucial for a proper description of experimental reality.
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Lee, Sang Hwa. "Quenching effects, mechanisms, and kinetics of nickel(II) chelates and carotenoids in singlet oxygen oxidation of soybean oil /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487670346873481.
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Mekideche, Abdeslam. "Effet mémoire de forme et plasticité de transformation dûs à la transition C. F. C. ↔T. F. C. D'alliages Mn Cu riches en Mn." Lyon 1, 1985. http://www.theses.fr/1985LYO19016.
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Les alliages Mn-Cu riches en Mn ( 80-100 %) trempés depuis haute température à 1’état cubique à face centrées présentent vers la température ambiante une transformation sans diffusion c. F. C. ↔ t. F. C. à caractère quasi-martensitique. Ce travail a pour objet l'étude de la plasticité de transformation et de la mémoire de forme liés à cette transition. Un appareil simple permettant la mesure de la déformation de flexion de plaquettes en fonction de la température et de la charge appliquée , a été mis au point et utilisé. Il a été montré que la plasticité de transformation comme l'effet mémoire de forme sont relativement limités en amplitude ( 0,6 % ) et qu 'ils s'accompagnent presque toujours de déformation plastique vraie. Des mesures complémentaires : diffraction X, résistivité, frottement intérieur et observation au microscope optique ont été effectuées et ont contribué à montrer qu'une partie importante de la déformation de l'effet mémoire est à attribuer à la variation des paramètres cristallins de la martensite t. F. C. Lorsqu'il y a dissymétrie entre les variantes.
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Allen, F. S. "The effect of quenchant characteristics on the generation of thermal stress and strain in steel plates." Thesis, Sheffield Hallam University, 1987. http://shura.shu.ac.uk/19661/.
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A visco-elastic-plastic mathematical model developed at Sheffield City Polytechnic was used to calculate the thermal stress and strain generated during the quenching of an infinite plate of high hardenability steel (835M30) in water, nine experimental oils and a polymer. In.the case of water, previous comparisons between experimental and calculated residual strains was poor. This discrepancy, during the present investigation, was reduced by introducing into the model the relationship between actual surface temperature and surface heat transfer coefficients and by incorporating the effects of various surface finishes into the model. However this discrepancy still remains to a limited extent. The same mathematical model was used to investigate the quenching characteristics of a number of experimental oils: overall the calculatedresidual stresses and strains compared well with the corresponding experimental data. The experimental oilscontained mixtures of additives. Those based on sodiumsulphonate increased the rate of cooling during quenching and the associated absolute residual stresses at a fixed point in the plate. Simultaneously the residual strains were reduced. The use of the succinimide additive produced converse effects in each case. The investigation also included the quenching of plates in polymer solutions of varying concentrations to provide a basis for comparison between the three most commonly used quenchants, viz. water, oil and water soluble polymers. The results indicated that in terms of the residual stresses and strains the oils produced smaller values particularly in the latter case when compared with the polymers. However when compared with water both the oils and water soluble polymers produced significantly smaller residual stresses and strains. The quenching characteristics were also investigated by the use of photography which gave an insight into the cooling characteristics of each quenchant. A water quench produced masses of fine bubbles during the nucleate boiling stage whilst this stage was characterised by large vapour blisters moving up the face of the plate in the case of the experimental oils. Previous photographic evidence indicated that solid polymer was deposited during quench and coated the plate with a gel-like substance which returned back into solution when the temperature was low enough.
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Ma, Shuhui. "A methodology to predict the effects of quench rates on mechanical properties of cast aluminum alloys." Link to electronic dissertation, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050106-174639/.
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Dissertation (Ph.D.)--Worcester Polytechnic Institute.<br>Keywords: Time-Temperature-Property curve, Jominy End Quench, ANOVA analysis. Quench Factor Analysis, Taguchi design, Polymer quench, Cast Al-Si-Mg alloys, Quenching, Heat treatment. Includes bibliographical references (p.115-117).
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Koka, Vivian Dzigbodi. "A Study of the Effects of Titanium Dioxide Nanoparticles on the Fluorescent Intensity of Fluorescent Compounds in the Presence of Known Quenchers." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1384.
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Titanium Dioxide is a naturally occurring oxide of titanium. It has a wide range of uses in commercial products for providing whiteness and opacity. It has photocatalytic properties and can also be used to produce electricity in its nanoparticles form. This research is focused on investigating the effect of titanium dioxide nanoparticles in analysis of compounds using luminescence-based techniques. Quenching, which is one of the basic problems of fluorescent measurements, was studied in the presence of molecular oxygen and methyl iodide. The rutile phase of titanium dioxide nanoparticles was synthesized by the acid hydrolysis of titanium isobutoxide at low temperatures with nitric acid. The crystalline powder was dissolved at different concentrations and used to monitor the fluorescence intensities of carbazole, pyrene, and fluoranthene in the presence of methyl iodide and oxygen. Quenching by molecular oxygen was studied by comparing the fluorescence intensities of compounds with and without degassing the solutions. Titanium Dioxide was found to exhibit interesting effects on the fluorescent intensities of these compounds in the presence of quenchers.
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Odame-Ankrah, Charles Anim. "Studies of Titanium Dioxide Nanoparticles and Surfactants Effects, Singly and in Combinations, on Luminescence Intensity of Some Aromatic Compounds." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etd/1799.
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Luminescence techniques are sensitive, selective, and widely used in analysis. Luminescence intensity is attenuated by quenchers. This research has focused on the use of surfactants such as CTAB, SDS, and TX-100 singly or together with TiO2 nanoparticles to evaluate their individual and combined effects on some fluorescent aromatic compounds such as pyrene, fluoranthene, anthracene, phenanthrene, and carbazole. Rutile phase TiO2 was synthesized using the low temperature sol-gel method. Carbazole and phenanthrene were severely quenched by all surfactants singly or in combination with TiO2. Anthracene and fluoranthene showed some enhancement in their luminescence intensity. The most dramatic effect was observed on the fluorescence intensity of pyrene. Pyrene showed enhanced fluorescence after degassing the solution alone or with the addition of the surfactants alone or in combination with TiO2 after degassing. These results showed that surfactants and TiO2 nanoparticles either singly or in combination should be useful for analysis employing luminescence techniques.
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Andrae, Johan. "Wall Related Lean Premixed Combustion Modeled with Complex Chemistry." Doctoral thesis, KTH, Kemiteknik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3455.
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Increased knowledge into the physics and chemistrycontrolling emissions from flame-surface interactions shouldhelp in the design of combustion engines featuring improvedfuel economy and reduced emissions. The overall aim of this work has been to obtain afundamental understanding of wall-related, premixed combustionusing numerical modeling with detailed chemical kinetics. Thiswork has utilized CHEMKIN®, one of the leading softwarepackages for modeling combustion kinetics. The simple fuels hydrogen and methane as well as the morecomplex fuels propane and gasified biomass have been used inthe model. The main emphasis has been on lean combustion, andthe principal flow field studied is a laminar boundary layerflow in two-dimensional channels. The assumption has been madethat the wall effects may at least in principle be the same forlaminar and turbulent flames. Different flame geometries have been investigated, includingfor example autoignition flames (Papers I and II) and premixedflame fronts propagating toward a wall (Papers III and IV).Analysis of the results has shown that the wall effects arisingdue to the surface chemistry are strongly affected by changesin flame geometry. When a wall material promoting catalyticcombustion (Pt) is used, the homogeneous reactions in theboundary layer are inhibited (Papers I, II and IV). This isexplained by a process whereby water produced by catalyticcombustion increases the rate of the third-body recombinationreaction: H+O2+M ⇔ HO2+M. In addition, the water produced at higherpressures increases the rate of the 2CH3(+M) ⇔ C2H6(+M) reaction, giving rise to increased unburnedhydrocarbon emissions (Paper IV). The thermal coupling between the flame and the wall (theheat transfer and development of the boundary layers) issignificant in lean combustion. This leads to a sloweroxidation rate of the fuel than of the intermediatehydrocarbons (Paper III). Finally in Paper V, a well-known problem in the combustionof gasified biomass has been addressed, being the formation offuel-NOx due to the presence of NH3 in the biogas. A hybridcatalytic gas-turbine combustor has been designed, which cansignificantly reduce fuel-NOx formation. Keywords:wall effects, premixed flames, flamequenching, numerical modeling, CHEMKIN, boundarylayerapproximation, gasified biomass, fuel-NOx, hybrid catalytic combustor.<br>QC 20100504
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Berroudji, Sid-Ahmed. "Cinétiques de mise en ordre à courte distance et caractéristiques des lacunes et des autointerstitiels dans des alliages [gamma]-FeNiCr." Grenoble 1, 1988. http://www.theses.fr/1988GRE10095.
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Etude des cinetiques de mise en ordre dans les alliages fe::(59)ni::(25)cr::(16) et fe::(9)ni::(75)cr::(16) par mesure de resistivite electrique. Determination des caracteristiques des lacunes et autointerstitiels par les techniques de trempe a l'helium liquide, de mesure de resistivite lors des cycles alternes de chauffage et de trempe ou lors de cycles continus. Evaluation des enthalpies de formation, de migration et d'autodiffusion. Influence de la composition. Analyse des sursaturations dynamiques de defauts lors de l'irradiation. Determination des frequences de saut des autointerstitiels et de leur enthalpie en fonction de la composition chimique
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Fahlkrans, Johan. "Effects of manufacturing chain on mechanical performance : Study on heat treatment of powertrain components." Licentiate thesis, KTH, Industriell produktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-163665.
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The increasing demands for lightweight designs with high strength call for improved manufacturing processes regarding heat treatment of steel. The manufacturing process has considerable potential to improve the mechanical performance and to obtain more reliable results with less variation. The goal of this thesis is to establish new knowledge regarding improved manufacturing processes in industrial heat treatment applications. Three research questions with associated hypotheses are formulated. Process experiments, evaluation of the mechanical performance, and modelling of the fatigue behaviour assist in answering the questions. The gas quenching procedure following low-pressure carburising differs from the conventional procedure of gas carburising and oil quenching. It is shown that the introduction of a holding time during the low-temperature part of the quench has a positive effect on mechanical properties, with some 20 percent increase in fatigue strength. This is attributed to increased compressive surface residual stress and stabilisation of austenite. Tempering is a common manufacturing process step following hardening in order to increase the toughness of the steel. However, the research shows that the higher hardness from eliminating tempering from the manufacturing process is beneficial for contact fatigue resistance. The untempered steel showed not only less contact fatigue damage but also a different contact fatigue mechanism. Straightening of elongated components is made after heat treatment in order to compensate for distortions. The research shows that straightening of induction hardened shafts may lead to lowering of the fatigue strength of up to 20 percent. A fracture mechanics based model is developed to estimate the effects of straightening on fatigue strength.<br>Ökande krav på höghållfasta lättviktskonstruktioner kräver förbättrade tillverkningsprocesser för värmebehandling av stål. Det finns stor potential att förbättra mekanisk prestanda och att erhålla mer tillförlitliga resultat med mindre variation genom att förbättra tillverkningsprocessen. Målet med denna avhandling är att etablera ny kunskap kring tillverkningsprocesser inom industriella värmebehandlingsapplikationer. Tre forskningsfrågor med tillhörande hypoteser formuleras. Processexperiment, utvärdering av mekanisk hållfasthet och modellering av utmattningsbeteende bygger upp besvarandet av frågorna. Gaskylning som följer lågtrycksuppkolning skiljer sig från det konventionella förfarandet med gasuppkolning och släckning i olja. Resultaten visar att en hålltid i den nedre delen av kylningsförloppet har positiv inverkan på utmattningshållfastheten. Orsaken till förbättringen hänförs till ökade tryckrestspänningar samt stabilisering av austenit. Anlöpning är en vanlig tillverkningsprocess som efterföljer härdning för att öka stålets seghet. Forskningen visar däremot att den högre hårdheten för oanlöpt stål är fördelaktig för motstånd mot kontaktutmattning. Oanlöpt stål visade mindre mängd kontaktutmattningsskador och även en annan skademekanism. Riktning av långa komponenter görs efter värmebehandling för att kompensera för de formförändringar som uppstår. Forskningen visar att riktning av induktionshärdade axlar kan leda till sänkning av utmattningshållfastheten med upp till 20 procent. En brottmekanisk modell som uppskattar effekten av riktning på utmattningshållfasthet presenteras.<br><p>QC 20150410</p>
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Laisney, Jérôme. "Influence de l’environnement sur la commutation et la bistabilité thermique de micro- et de nanoparticules à transition de spin." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112002.
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Les composés à transition de spin forment une classe spécifique de matériaux pour lesquels la commutation de l’état de spin du centre métallique peut être pilotée par divers stimuli (T, P, irradiation lumineuse, …) et s’accompagne de changements remarquables des propriétés physiques (magnétiques, optiques, structurales ou encore vibrationnelles). Ils se distinguent des autres matériaux commutables par l’observation, pour un certain nombre d’entre eux, de processus coopératifs à l’état solide, donnant lieu à l’ouverture d’une hystérèse thermique (bistabilité) particulièrement intéressante pour le stockage de l’information. Un des challenges technologiques actuels est de réduire la taille des matériaux susceptibles d’application et de les mettre en forme au sein de dispositifs sans altérer pour autant leurs propriétés. Les objectifs de la thèse ont été d’élaborer des micro- et nanoparticules à conversion de spin à partir de composés moléculaires présentant une transition de spin du premier ordre à l’état massif, puis d’étudier et analyser l’influence de la taille et de la matrice dispersante sur les processus de transition de spin. Après un premier chapitre introductif portant sur les matériaux à transition de spin, les méthodes de nanochimie et de mise en forme, le deuxième chapitre décrit l’élaboration de particules des composés FeII(phen)2(NCX)2 (X = S, Se) et [FeIII(3-OMeSalRen)2]PF6 (R = Me, Et). Comme la technique de précipitation rapide convient pour des composés ioniques, son application à FeII(phen)2(NCX)2 composé neutre, a nécessité la mise au point d’une synthèse indirecte de particules, basée sur l’extraction de ligand de précurseurs solubles, et le contrôle via des paramètres expérimentaux, des étapes de nucléation-croissance. De nouvelles particules de composés ioniques de Fe(III) [FeIII(3-OMeSalRen)2]PF6 (R = Me, Et) et des films minces contenant ces particules dispersées dans un polymère (PVP) ont été préparées. Les études magnétique et optique de ces films montrent que la matrice et la mise en forme modifient toujours les caractéristiques de la transition de spin des particules.La deuxième partie des travaux a été consacrée à l’étude des effets d’environnement. L’interaction entre des microparticules de Fe(phen)2(NCS)2 et des matrices vitreuses (Tg > T1/2; T1/2, étant la température de transition) peut conduire à l’ouverture d’un large cycle d’hystérésis, déplacé vers les plus basses températures. Cette zone de bistabilité a été examinée à l’aide de la méthode FORC (First-Order Reversal Curves). L’analyse a permis d’établir l’existence de composantes réversibles attribuées aux interactions élastiques à l’interface matrice/particule et au changement de volume de la particule à transition de spin.L’étude des effets de matrice et de taille a été poursuivie avec des micro- et nanocristaux de [FeIII(3-OMeSalEen2]PF6 dispersés dans des polymères ou des liquides moléculaires formant des verres à basse température. L’encapsulation dans des verres rigides de particules haut-spin (T1/2 < Tg) ou bas-spin (T1/2 > Tg) donnent lieu à des conversions de spin déplacées respectivement vers les plus basses ou plus hautes températures, éventuellement des processus coopératifs avec hystérésis. Le renforcement de la coopérativité et la bistabilité observées dans le second cas ont été interprétés comme résultant des contraintes mécaniques vis-à-vis du changement de volume BS-HS de la particule. Enfin, le changement d’état de la matrice induit par des étapes de trempe (ou recuit) en-dessous (au-dessus) de la température de transition vitreuse, a été exploité pour moduler ces effets. Dans la perspective d’une application, de nouvelles études de composites ont été engagées avec des complexes présentant une transition de spin proche de la température ambiante. Le choix de la matrice dispersante selon certains critères (nature chimique, température de transition vitreuse) a permis de retrouver certains effets<br>Spin-transition compounds are a class of materials for which the spin-state switching of the metal center can be controlled by various stimuli (T, P, light irradiation,...) and produces dramatic changes of physical properties (magnetic, optical, structural or vibrational). With respect to the set of switchable materials, a number of spin-transition compounds exhibit at solid-state cooperative processes and thermal hysteresis loops (bistability), particularly suitable for information storage. One of the current technological challenges is to integrate in devices such potentially interesting materials without altering their properties. The goal of the research, recently developed by several teams, is to determine the smaller size of object in which an information can be stored, and thus to understand the effect of downsizing on cooperativity and bistability. Therefore, the objectives of the Ph-D thesis were (i) to synthesize spin-crossover nano- and microparticles from molecular materials that in the form of bulk undergo a first-order phase transition; (ii), to investigate the importance of particles size and matrix effects on the spin-transition process.After a first chapter in which the spin crossover materials are introduced, the second chapter describes the synthesis of particles of FeII(phen)2(NCX)2 (X = S, Se) and [FeIII(3-OMeSalRen)2]PF6 (R = Me, E) compounds. As the fast precipitation technique essentially suits for ionic compounds, its application to neutral ones like FeII(phen)2(NCX)2, has been made possible by an indirect syntheses based on the ligand extraction from soluble precursors and the control of nucleation and growth processes of neutral products via experimental parameters. New particles of [FeIII(3-OMeSalEen)2]PF6 and thin films containing them after their dispersion in a polymeric matrix (PVP) have been prepared. The study of these films with UV-vis and magnetic measurements has raised the issue of the impact of the polymeric matrix and processing on the spin transition properties of these particles.The second part of the manuscript focuses on the interaction between the spin-crossover particles and the dispersing medium. This interaction between microparticles of Fe(phen)2(NCS)2 and glassy matrices (Tg > T1/2, T1/2, being the transition temperature) may result in the observation of large hysteresis loops shifted towards lower temperatures. This bistability has been examined with the FORC (First-Order Reversal Curves) method, magnetic measurements and a theoretical model. This analysis has shown the existence of reversible components associated to the particles/matrix interactions and the change of volume of spin-crossover particles.In a third part, the study of matrix and size effect has been pursued with micro- and nanocrystals of [FeIII(3-OMeSalEen2]PF6 encapsulated in polymeric or molecular liquids which form glasses at sufficiently low temperature. The encapsulation in rigid glasses of high spin (T1/2 < Tg) or low spin (T1/2 > Tg) particles give rise to transitions shifted towards lower or higher temperature respectively, possibly with cooperativity and hysteresis. The reinforcement of cooperativity and the bistability observed in the second case have been accounted for by the effect of the mechanical stress exerted by the glassy matrix on the particle volume. In addition, it has been shown that a thermal treatment of matrices (quenching or annealing steps below or above the glass transition) results in the modulation of the matrix effects. Finally, in the last chapter, a few composites including compounds undergoing a spin transition close to room temperature have been shortly investigated in presence of dispersing matrices. The choice of the matrices characteristics (chemical nature, glass transition temperature) has allowed some of these effects to be observed
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Wilson, Flore Adjélé. "Étude du mécanisme de photoprotection lié à l’Orange Carotenoid Protein et ses homologues chez les cyanobactéries." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS503/document.
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La lumière est essentielle pour les organismes photosynthétiques qui convertissent l'énergie solaire en énergie chimique. Cependant, la lumière devient dangereuse lorsque l'énergie qui arrive aux centres réactionnels de l'appareil photosynthétique, est en excès par rapport à l’énergie consommée. Dans ce cas, la chaîne de transport d'électrons photosynthétiques se réduit et les espèces réactives de l'oxygène (ROS) sont accumulées, notamment au niveau des deux photosystèmes, PSI et PSII. Les cyanobactéries ont développé des mécanismes photoprotecteurs qui diminuent l'énergie transférée au PSII atténuant ainsi l'accumulation de ROS et les dommages cellulaires, comme l’extinction non-photochimique (NPQcya) induite par la lumière bleue-verte. La soluble Orange Caroténoïde Protéine (OCPo) est essentielle pour ce mécanisme de photoprotection. L'OCP agit comme un senseur de l’intensité lumineuse et un inducteur de la dissipation d'énergie des phycobilisomes (PBS), l'antenne extra-membranaire des cyanobactéries. L'OCP est la première protéine photo-active à caroténoïde connue comme senseur. Une forte lumière bleue-verte déclenche des changements structurels dans l'OCPo qui induisent une forme active, rouge (OCPr). Le domaine N-terminal de l’OCPr, en s’intercalant entre les trimères externes d’un des cylindres basaux du cœur du PBS, augmente la dissipation thermique de l'énergie au niveau de l'antenne. L'OCP possède aussi une autre fonction : l’extinction de l’oxygène singulet, qui protège les cellules du stress oxydatif. Pour récupérer pleinement la capacité de l’antenne en faible lumière, une deuxième protéine est nécessaire, la "Fluorescence Recovery Protein" (FRP), dont le rôle est de détacher l’OCPr des PBS et d’accélérer sa reconversion en OCPo inactive. Ce manuscrit est un état des lieux des connaissances et des dernières avancées sur le mécanisme de NPQ associé à l'OCP dans les cyanobactéries<br>Photosynthetic organisms use light energy from the sun in order to perform photosynthesis and to convert solar energy into chemical energy. Absorbance of excess light energy beyond what can be consumed in photosynthesis is dangerous for these organisms. Reactive oxygen species (ROS) are formed at the reaction centers and collecting light antennas inducing photooxidative damage which can lead to cell death. In cyanobacteria, one of these photoprotective mechanisms consists to reduce the amount of energy arriving to the reaction centers by thermal dissipation of the excess absorbed energy. Energy dissipation is accompanied by a decrease of Photosystem II-related fluorescence emission called non-photochemical quenching (NPQ). The soluble Orange Carotenoid Protein (OCPo) is essential for this photoprotective mechanism. The OCP is the first photo-active protein with a carotenoid known as light intensity sensor and acts as energy quencher of the phycobilisome (PB), the extra-membrane antenna of cyanobacteria. Structural changes occur when the OCPo absorbs a strong blue-green light leading to a red active form (OCPr). The N-terminal domain of OCPr burrows into the two external trimers of the core basal APC cylinders of the PB and increases thermal energy dissipation at the level of antenna. The OCP has an additional function in photoprotection as oxygen singlet quencher protecting cells from oxidative stress. Under low light conditions, to recover the full antenna capacity, a second protein is needed, the "Fluorescence Recovery Protein" (FRP), whose role is to detach the OCPr from the PB and accelerate its conversion into an inactive OCPo. In this manuscript, I will review the knowledge about the OCP, since the discovery of the mechanism and its characterization to the latest advances on the OCP-related-NPQ mechanism in cyanobacteria
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Tong, Shun-Chen, and 童順晨. "The Effect of PVP Polymer Quenchant Parameters and Nano-Particle Additives on Quenching Characteristics for Steels." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/su456f.
Full textAbstract:
碩士<br>國立虎尾科技大學<br>材料科學與綠色能源工程研究所<br>103<br>The purpose of this article is to investigate the effect of PVP type polymer quenchant parameters including concentration, fluid agitation velocity, temperature, and nano-particle additives on quenching characteristics for several selected steels. By changing the parameters of PVP polymer quenchant and adding montmorillonite nano-particle additives, we reveal the effect of these parameters on the hardness distribution, hardening depth, quenching distortion and microstructures for several selected steels, and also look for the optimum quenchant parameters to reduce the quenching distortion based on hardenable condition. Finally, a comparison was conducted on the quenching characteristics and the improvement condition of quenching distortion between polymer quenchant quenching and conventional oil (temperature at 70 ° C) quenching in order to estimate the feasibility of PVP polymer quenching media to replace conventional mineral oil on quenching application for steels.
The experimental results show that quenched hardness of all selected steels in this study is decreased as the polymer concentration of quenchant is increased from 10% to 30% with fixed fluid agitation velocity at room temperature (26°C). Hardness decline of JIS-SNCM439 and JIS-SKD61 steels with high hardenability is not large; hardness downward tendency of middle hardenability steel JIS-SCM440 is obvious; and hardness of lower hardenability steel JIS-S45C will be significantly reduced, too. The hardness of all selected steels will increase as fluid agitation velocity of quenchant increases at room temperature (26°C); hardness increment margin is low for high hardenability steels JIS-SNCM439 and JIS-SKD61, and hardening depth of middle hardenability steel JIS-SCM440 and lower hardenability steel JIS-S45C can be significantly enhanced as fluid agitation velocity is increased. Hardness of quenched specimen will be reduced as quenchant temperature was raised from room temperature (26° C) to 40°C; the lower is the steel hardenability, the higher will be the effect result. Hardness of quenched specimens for high hardenability steels JIS-SNCM439 and JIS-SKD61 will decrease slightly as PVP polymer quenchant was added the additives of montmorillonite nano-particle; it is quite obvious that montmorillonite nano-particle has a barrier effect of heat transfer.
When polymer concentration is increased from 10% to 30% and fluid agitation velocity of quenchant is constant at room temperature (26 ° C), the maximum deflections of unit length of high hardenability steels JIS-SNCM439, JIS-SKD61 and middle hardenability steel JIS-SCM440 will reduce; but the effect is not obvious significantly as polymer concentration exceeds about 20%. Maximum deflection of unit length for lower hardenability steel JIS-S45C will decrease as the polymer concentration is increased from 10% to 20%; but cross-section hardness of specimen cannot achieve hardening standards as the concentration is increased to 20%. Proper fluid agitation velocity can reduce quenching distortion of specimen; maximum deflection of unit length for specimen can be reduced to minimum as fluid agitation velocity is at 0.3m/sec for above-mentioned several selected steels. When quenchant temperature was raised from room temperature (26°C) to 40°C, maximum deflection of unit length for specimen will be decreased. Maximum deflection of unit length for high hardenability steels JIS-SNCM439 and JIS-SKD61 can be effectively reduced as montmorillonite nano-particle was added to PVP type polymer quenchant.
The selected steels were quenched by using optimum polymer quenchant parameter and conventional oil quenchant parameter in this study, quenched steels will obtain approximate hardness. PVP type polymer quenchant is applicable to quenching hardening for JIS-SNCM439 and JIS-SKD61, but is not applicable for quenching of JIS-SCM440 and JIS-S45C. In this study, quenchant parameters of reducing quenching distortion for JIS-SNCM439 and JIS-SKD61, JIS-SCM440, JIS-S45C is respectively polymer concentration at 20% (and adding 4% montmorillonite nano- particle), 20%, 15% with fluid agitation velocity 0.3m/sec at room temperature (26 ° C).
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Che-WeiLin and 林哲緯. "Effect of Uphill Quenching on the Microstructure and Properties of FC300." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/73604012812030875810.
Full textAbstract:
碩士<br>國立成功大學<br>機械工程學系碩博士班<br>100<br>Precision machine tool industry has been toward the high precision and high stability, so the request of cast iron was more strict and hard to achieve. If the precision machine tool was made of unstable gray cast iron, the error of accuracy would be accumulated by using time increased. In this study, gray cast iron(FC300) by used material in precision machine tool was studied. Using uphill quenching to compare with the influence produced by natural aging is a method to research stability of gray cast iron. In this experiment, feasibility of uphill quenching prompt gray cast iron stable and the evolution of microstructure with different times of cycle were discussed. Finally, the benefit it produced would be evaluated via hardness test.
The experimental results showed that the phenomenon of graphitization on the part of pearlite matrix would be observed slightly. Part of pearlite matrix dissolved by several times of plastic strain to ferrite and graphite. For the graphite morphology, dimension of graphite increased with cycles and the duration of uphill quenching. Result of hardness did not change significantly, because the phenomenon of graphitization only discover in part of matrix. Moreover, the sample was treated with uphill quenching, and the distortion was observed via residual stress released. Finally, uphill quenching might have some benefits for stabilization of gray cast iron.
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"Study of Layout Techniques in Dynamic Logic Circuitry for Single Event Effect Mitigation." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-09-2253.
Full textAbstract:
Dynamic logic circuits are highly suitable for high-speed applications, considering the fact that they have a smaller area and faster transition. However, their application in space or other radiation-rich environments has been significantly inhibited by their susceptibility to radiation effects. This work begins with the basic operations of dynamic logic circuits, elaborates upon the physics underlying their radiation vulnerability, and evaluates three techniques that harden dynamic logic from the layout: drain extension, pulse quenching, and a proposed method. The drain extension method adds an extra drain to the sensitive node in order to improve charge sharing, the pulse quenching scheme utilizes charge sharing by duplicating a component that offsets the transient pulse, and the proposed technique takes advantage of both. Domino buffers designed using these three techniques, along with a conventional design as reference, were modeled and simulated using a 3D TCAD tool. Simulation results confirm a significant reduction of soft error rate in the proposed technique and suggest a greater reduction with angled incidence. A 130 nm chip containing designed buffer and register chains was fabricated and tested with heavy ion irradiation. According to the experiment results, the proposed design achieved 30% soft error rate reduction, with 19%, 20%, and 10% overhead in speed, power, and area, respectively.
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Hu, Yao-Jen, and 胡耀仁. "The Quenching Effect of Cold Walls on Steady Laminar Premixed H2/O2 Flame." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/86570099330314332652.
Full text
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Li, Yan-Shen, and 黎諺燊. "Effect of Minor Zr and Cold Working on Quenching Sensitivity of Al-4.7Zn-1.6Mg Alloys." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/gmnjqs.
Full textAbstract:
碩士<br>國立中央大學<br>材料科學與工程研究所<br>105<br>We investigate the effect of minor Zr and cold working on
quenching sensitivity of Al4.7Zn1.6Mg alloy by microstructure
observing, DSC measurement and Jominy End Quench Test, and so on.
The result shows that Zr element can inhibit quenching sensitivity
significantly, while cold working make quenching sensitivity of
Al4.6Zn1.6Mg(0.1Zr) obviously. Recrystallization motivation of cold
worked Al4.6Zn1.6Mg0.1Zr alloy is larger than hot extruded one and
there are many low coherency Al3Zr particles as heterogeneous
nucleation sites in the new grains, so the quenching sensitivity of cold
worked alloy is more than hot worked one. Longterm solution treatment
has no certain impact on hot worked Al4.6Zn1.6Mg alloy, but make
average grain size of cold worked Al4.6Zn1.6Mg alloy growth, reduce
the grain boundary area and lower quenching sensitivity of cold worked
Al4.6Zn1.6Mg alloy slightly. Longterm solution treatment enhance
recrystallization fraction of Al4.6Zn1.6Mg0.1Zr alloy, and increase
the amount of precipitation of stable phase. The amount of precipitation
of stable phase influence hardness ineffectively in the air cooling end of
Jominy End Quench test tube of hot worked Al4.6Zn1.6Mg0.1Zr
alloy, but effectively for cold worked Al4.6Zn1.6Mg0.1Zr alloy.
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Ou, Siou-Ci, and 歐修齊. "The Effect of Carburizing Parameters and Quenching Hardening Methods on Surface Hardening Characteristics for Steels." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/rs48z6.
Full textAbstract:
碩士<br>國立虎尾科技大學<br>材料科學與工程系材料科學與綠色能源工程碩士班<br>104<br>The purpose of this study is to investigate the effect of different carburizing parameters and quenching method on hardness distribution, hardening depth, quenching distortion, wear resistance and microstructures for two common carburizing steels which are JIS-S15C and JIS-SCM415 respectively. The study also looks for the optimum parameters that can reduce the quenching distortion and increase the wear resistance of the steels specimens which were high frequency induction hardened after carburizing. Finally, comparisons of quenching characteristics investigation and quenching distortion improvement between high frequency induction quenching and conventional direct quenching were made for carburized steels.
The result indicates that JIS-S15C shows deeper carburizing depth than JIS-SCM415, but shallower 0.1~0.2mm hardening depth after conventional direction quenching at every carbon potential for both of carburizing specimens of JIS-S15C and JIS-SCM415. In the hardness, the surface hardness of JIS-SCM415 is more than that of JIS-S15C about HV20~60. Furthermore, the surface hardnesses of carburized specimens were increased with the carbon potential increasing. Both of JIS-S15C and JIS-SCM415 steels specimens form a super-hardness through high frequency induction hardening after carburizing at different carbon potential, the super-hardness (about HV910) of high frequency induction quenching is higher than that of direction quenching about HV100 after carburizing, and it can change the hardening depth by controlling the input power and motion velocity of the induction coil. The maximum deflection of unit length of the direct quenching for carburized specimen increases with the carbon potential increasing; the maximum deflection of unit length of the specimens through high-frequency induction quenching after carburizing is increased with the input power increasing or the motion velocity of the induction coil decreasing; the problem of quenching distortion of the specimens through high-frequency induction quenching after carburizing is remarkably improved. For the two kinds of steels, the improvement % of maximum deflection of unit length for specimens will increase as carbon potential is increased at constant input power, and the improvement % will also increase as input power is decreased at constant carbon potential. The improvement % varies with the parameters, the maximun improvement % of JIS-S15C is up to 67%~82%, and the improvement % of JIS-SCM415 is up to 85%~93% at different carbon potential. The result microstructures are different by changing input power and motion velocity of the induction coil, and which thereby affect the quenching distortion and the wear resistance. By using proper input power and motion velocity of the induction coil, the microstructures of specimens through high-frequency induction quenching after carburizing would become more refiner, and the retained austenite is less. Furthermore, the quenching distortion and the friction coefficient for the specimens through high frequency induction quenching after carburizing would be lower than the specimen which is direct quenching after carburizing.
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CHEN, YU-TING, and 陳玉庭. "Using fluorescence quenching effect to investigate the electrical neutralization ability for different aromatic organic compounds." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/cqc37x.
Full textAbstract:
碩士<br>國立聯合大學<br>環境與安全衛生工程學系碩士班<br>107<br>The sources of organic matter in water include natural organic matter and synthetic organic matter. Natural organic matter in water not only causes color, taste and odor problems, but also produces harmful disinfection by-products. Most part of natural organic matter in water is humic substances which has strong complexation ability with heavy metals. On the other hands, in synthetic organic matter, dye is used in the textile industry. The discharge of textile wastewaters has a negative effect on Water quality, reducing the light penetration, and consequently changing the aquatic ecosystem. Consequently, effectively removing organic matter from water through the chemical coagulation process continues to be considered as a fairly important index of water purification efficiency.
When the organic matter contains an aromatic heterocyclic structure and is excited by absorbing a specific radiation, it will eventually release the absorbed energy to the lower electronic energy level. Normally, the energy is released in the form of fluorescence. On the other hand, if the organic matter and metal ions are bonded to each other, the fluorescence intensity will be reduced. This phenomenon is known as the fluorescence quenching effect. In this study, the Stern-Volmer formula F0/F＝1+Kq[M] will be used to evaluate the ability of the Al3+ coagulant complexes with organic matter. Where F0 is the fluorescence intensity in the absence of Al3+quencher and F is the fluorescence intensity in the presence of Al3+quencher, [M] is the concentration of the quencher, and Kq is the equilibrium constant or quenching constant. Furthermore, the value of Kq also represents the electrical neutralization capacity of coagulant under different conditions such as pH, molecular weight, hydrophilicity, functional groups of organic compound and coagulant dosage etc.
The experimental results of fluorescence quenching effect on AlCl3 dosages in different aromatic organic compounds. (1) The smaller the molecular weight of natural organic matter have the larger Kq value. Indicating that smaller size molecular weight exhibits a higher maximum binding capacity due to a greater number of functional groups. (2) Under different pH, Reactive Blue 49 obtain the maximum Kq values than Direct Red 28 and Disperse Red 60 those often used in industry, demonstrating that more number of sulfonic groups in the dye molecule can intensify electrical neutralization ability.(3)Under conditions of pH=6,the Kq value of SA,QS and Phenyl phosphate is different. Due to the functional groups they contain, different of dissociation constant(pKa) cause the change of charge of organic matter.(4) the Reactive Blue 49 and aluminum ions is a chemical reaction of exothermic that experimental temperature in lower state has higher Kq value. Indicating that the Al3+ coagulant and functional groups of Reactive Blue 49 are bonded to each other and then produced static quenching effect.
All of results in this study show that the Kq value is a viable and simple method in operation to find the influencing factor of electrical neutralization ability between organic matter and aluminum coagulant and provide more accurate assessment to find the optimum coagulation conditions.
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CHEN, CHAO-FENG, and 陳昭鳳. "Using Fluorescence Quenching Effect to Investigate the Electrical Neutralization Ability for Different Types of Aluminum Ions." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/33536502646805205897.
Full textAbstract:
碩士<br>國立聯合大學<br>環境與安全衛生工程學系碩士班<br>105<br>In general, the electrical neutralization capacity of coagulant is affected by its polymerized status. For example, the main species of polyaluminum chloride is Al13 ([AlO4Al12(OH)24(H2O)12]7+), whose production process has occurred prehydrolysis phenomenon. It was reported that the polyaluminum chloride was more stable than Al3+ ions in an actual coagulation procedure. Therefore, the polyaluminum chloride performance to neutralize the electric charge of the suspended particles is better than that of the Al3+ ions. In the past, alkaline was added to increase the proportion of Al13. In contrast, mononuclear Al3+ coagulant hydrolysis was rapid and the coagulant was unstable in a coagulation process so that the electric charge of the particles could not be effectively neutralized. However, the coagulation process was greatly affected by basicity and pH value. Therefore, the electrical neutralization performance of Al13 was relatively poor in low basicity conditions.Hence, to produce good electrical neutralization coagulants, the subject of pre-hydrolysis process at high B value is worth to be studied.
Humic acid (HA) is a kind of natural organism, which can be widely removed by coagulation. Currently, Jar Test or Zeta Potential test are commonly used for the study of coagulant neutralizing the humic acid’s electric charges, but these are indirect evaluating methods. Hence, in this study, the humic acid will be the removal target, which using (1) Stern-Volmer linear equation will be used to obtain the constant value (Kq) of the fluorescence quenching efficiencies. Then, (2) a titration to form the humic-metal complex will be also conducted. According to the titration results, the effective stability constant (K’MY), which is determined from the side-reactions of both H+ and OH- ion generations in the humic-metal complex reaction, will also be studied. Through the above two “constant” studies are considered as the theoretical to evaluating its electrical neutralization efficiency under various conditions of pHs, coagulant dosages (Aluminum content percentages) and coagulant types.
The experimental results of fluorescence quenching effect on pH value of the solution and PACl dosagesin humic acid adding Polyaluminum Chloride with various B values (Basicity, B=[OH]/[Al]). (1) In acidic solution, compared of the Kq values of PACl with various B values are PACl-2.5>PACl-2.3>PACl-1.5>AlCl3; (2) In alkaline solution, compared of the Kq values of PACl with various B values are PACl-1.5>PACl-2.3>PACl-2.5>AlCl3; (3) Under the humic acid’s solution was pH=6, PACl of various B values are acquired the maximum Kq values. Indicating that PACl coagulation on humic acid is not affected by side-reactions of both H+ and OH- ion. Therefore, in this study, it is feasible to use the Kq value as a way to determine the ability of electrical neutralization, which can save the complexity of experiment and provide more accurate reaction constant than the past indirect way as surface potential.
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Lu, Yi-Tsang, and 呂佾倉. "Using Fluorescence Quenching Effect to Investigate the Electrical Neutralization Ability for Humic Acid and Different Types of Metals." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/586ed4.
Full textAbstract:
碩士<br>國立聯合大學<br>環境與安全衛生工程學系碩士班<br>107<br>Humic Acid (HA) is an important natural organic matter that existence of HA not only affects the color and smell of water, but also produces toxic disinfection by-products. Therefore, it is important to remove humic acid from drinking water.
Chemical coagulation is a commonly used technique in water treatment processes. Currently, electrochemical neutralization is associated with coagulant type, solution pH, solution temperature, stirring intensity and background ion reaction between coagulant and colloidal particles. Therefore, under the premise which has better electrical neutralization ability is worth discussing. This study used a Jar Test to investigate the complexing effect of humic acid and different doses of coagulant. Coagulants such as ferric chloride, ferric sulfate and aluminum chloride are commonly used coagulants that has different diversity. Many studies in the past have shown that the coagulation-precipitation process can be used to remove humic acid; humic acid has a fluorescent irradiation phenomenon, and its functional group such as carboxylic acids and phenolic groups could be bonded to metal ions, and weakening the fluorescence intensity. This phenomenon is known as the fluorescence quenching efficiencies. Therefore, fluorescence analysis is used to complex between humic acid and metal ions. Stern-Volmer linear equation will be used to obtain the constant value (Kq) of the fluorescence quenching efficiencies, a titration to form the humic-metal complex will be also conducted. According to the titration results, the effective stability constant (K’MY), which is determined from the side-reactions in the humic-metal complex reaction, will also be studied. Through the above two “constant” studies are considered as the theoretical to evaluating its electrical neutralization efficiency under different types of metals.
Adding different metals with humic acid and measuring the fluorescence intensity, it was found that if metal ions were not added to the humic acid solution, the fluorescence intensity increased as the pH value increased; almost no reaction was added when adding monovalent sodium ions. There has better complex effect when added ferric ions than added bivalent calcium ions. Therefore, the research select ferric ions. When adding different ferric ion concentrations into the humic acid solution, it is known that there is a significant fluorescence quenching efficiencies at pH=4 to 5.5, and the maximum quenching constant Kq=305,990 at pH=5, indicating acid and iron salt have a good complex reaction to realize change of extinction constant when ferric ions react with humic acid. It is found the humic acid and iron ions is a chemical reaction of exotherm that experimental temperature in lower state has higher Kq value. When the stirring intensity over than 100 rpm it will reach the maximum Kq value. If sodium chloride is contained in the water, it will interfere with the complex reaction between the coagulant and the iron ion. When phosphate is contained in water, it competes with humic acid for iron ions, causing a decrease in fluorescence quenching efficiencies.
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YANG, GUAN-ZHI, and 楊貫智. "A Study on the Absorptivity of Inconel 718 and Quenching Effect of AISI 1045 Steel by Laser Heating Method." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/f54s23.
Full textAbstract:
碩士<br>國立高雄應用科技大學<br>機械工程系<br>106<br>In this study, the temperature field of Inconel 718 nickel-based alloy in the pre-heating process was investigated. The influence of laser process parameters on the laser quenching of AISI 1045 steel was analyzed.
The Inconel 718 nickel-based alloy and AISI 1045 steel was heated by laser. The relation between the laser absorption of Inconel 718 nickel-based alloy and the variety of laser powers, rotational speeds and feed rates of laser is discussed. The feasibility of surface hardening for AISI 1045 steel was verified by using different feed rates and laser powers. In the experiment, the measurement with thermocouple and metallographic can be used to obtain temperature changes in different time domain, material melting width, melting depth, and hardening depth. The temperature field estimated by the finite element analysis model was proposed and compared with the experimental data.
The results show that the absorptivity of Inconel 718 under different rotational speeds and feed rates of laser is between 0.17 and 0.35. The finite element analysis model of AISI 1045 is verified by experiments and also showed good matching under different feed rates and laser powers. The temperature field can be successfully estimated by different process parameters. The effect of different rotational speeds and overlaps of laser on the quenching process can be estimated, and the ranges of feasible parameters in laser quenching were proposed.
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Beauchamp, David L. "The Effect of Salts on the Conformational Stability of Proteins." 2012. http://hdl.handle.net/1993/5306.
Full textAbstract:
It has long been observed that salts affect proteins in a variety of ways, yet comprehensive explanations for different salt effects are still lacking. In the work presented here, the effect of salts on proteins has been investigated through three different effects: the hydrophobic effect; their conformational stability; the hydrogen bonding network of water in a protein’s hydration shell. UV-vis absorbance and fluorescence spectroscopy were used to monitor changes in two model systems, the phenol-acetate contact pair and the model enzyme ribonuclease t1. It was shown that salts affect the hydrophobicity of the contact pair according to their charge density, induced image charges play an important role in the observed salt-induced increase of ribonuclease t1 stability, and that salts affect ribonuclease t1 activity through modulation of the hydrogen bonds of water in the enzyme’s hydration shell. This work contributes a greater understanding of the effect of salts on proteins.
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Huang, Shun-Hong, and 黃舜宏. "The Effect of High Frequency Induction Hardening Parameters, Pre-heat Treating Conditions and Quenching Mediums on Surface Hardening Characteristics for Some Selected Steels." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/ab3sja.
Full textAbstract:
碩士<br>國立虎尾科技大學<br>材料科學與工程系材料科學與綠色能源工程碩士班<br>104<br>In this study, JIS-S45C, JIS-SCM440 and JIS-SUJ2 steels which were pre-heat treated with different conditions were conducted high frequency induction surface hardening by using different quenching mediums. The objective of this study was to clarify the effect of high frequency induction hardening parameters (input power, motion velocity of the coil), pre-heat treating conditions (normalizing, thermal refining) and quenching mediums (water, 5%PVP polymer quenchant) on the distribution of hardness, hardening depth, microstructures, quenching distortion and wear resistance by a series of experiments.
The experimental results show that as the input power is increased or the motion velocity of the coil is reduced, the hardening depth of all steels specimens through the high frequency induction hardening will increase; and will also increase the surface hardness of JIS-SUJ2, it was increased about HV20~HV180, but it will not significantly affect the surface hardness of JIS-S45C and JIS-SCM440. With increasing depth of hardening (the hardness which is more than HV550), the quenching distortion of induction hardened steels specimens will be increased, but the wear resistance of steels specimens will be better. Comparing with the normalizing (JIS-SUJ2 is as-spheroidized steel), the JIS-S45C and JIS-SUJ2 steels specimens which were thermal refined will obtain the higher surface hardness and hardening depth through the high frequency induction hardening (the surface hardness of JIS-S45C was increased about HV20~30, JIS-SUJ2 was increased about HV110~290, and the hardening depth of both steels specimens was increased about 0.2mm~0.5mm). Either the quenching distortion or the wear resistance of both steels specimens will be increased. The wear weight loss of JIS-S45C was reduced 0.6mg under parameter of 85kW-30mm/s and JIS-SUJ2 was reduced 0.17mg under parameter of 90kW-25mm/s. The JIS-SCM440 steels specimens with two different pre-heat treatment conditions show have no significant differences in surface hardness, hardening depth and quenching distortion after high frequency induction hardening, but the JIS-SCM440 which was thermal refined has the better wear resistance, the wear weight loss was reduced 6.6mg under parameter of 85kW-30mm/s. By using 5% PVP polymer quenchant to replace water as a quenching medium for three kinds of steels, it has no effect on their surface hardness, hardening depth and wear resistance; it will only improve the quenching distortion (maximum deflection of unit length) of JIS-SUJ2 steel, the quenching distortion of as-spheroidized steel was improved about 27~44% and thermal refined steel was improved about 32~40%, but it has no distinct improvement for the others.
The surface layers of all steels specimens through the high frequency induction hardening, except for the JIS-SUJ2 which was thermal refined, have ferrite microstructure by reducing the input power or increasing the motion velocity of the coil, but the ferrite will significantly decrease by increasing input power or reducing the motion velocity of the coil. The amount of ferrite microstructure will be increased with the distance farther from the surface of the specimen; the transition zone will be widened as the motion velocity of the coil reduces, and considerable quantity of original microstructures at transition zone will appear.
Only JIS-SUJ2 steel specimen which was thermal refined hasn’t ferrite microstructure from optical microscope observation in the three kinds of steels specimens through the high frequency induction hardening. The major diffraction peak of JIS-SUJ2 steel specimen which was thermal refined is martensite by X-ray diffraction analysis; and the diffraction peaks of the others steels specimens are martensite and ferrite, all of the three kinds of steels specimens through the high frequency induction hardening have not retained austenite.
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Schwerg, Juljan Nikolai [Verfasser]. "Numerical calculation of transient field effects in quenching superconducting magnets / Juljan Nikolai Schwerg." 2010. http://d-nb.info/1001586972/34.
Full text
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Cai, Lezhen. "Mechanisms and salt effects in photoredox and quenching process involving cobalt (III) complexes." Thesis, 1996. https://dspace.library.uvic.ca//handle/1828/9694.
Full textAbstract:
The novel complexes [special characters omitted] and
[special characters omitted] were prepared and characterized. Photoredox quantum
yields for the formation of [special characters omitted] from the above compounds were measured on
irradiation at 360 nm to be 0.065, 0.082, 0.0088 and 0.0040 respectively. With added
thiocyanate a significant increase in ΦCo2+ occurred. This can be modeled in two ways;
(i) scavenging of thiocyanate radical from an initial caged radical pair giving 6-25 ps
estimates for the lifetime of the latter species; (ii) photolysis of a thiocyanate/complex
ion pair, giving formation constants of 0.19, 0.09, 0.08 and 0.05 for the complexes
[special characters omitted] and [special characters omitted] respectively. Subnanosecond
laser flash photolysis studies showed evidence for the formation of [special characters omitted].
The effects of added electrolytes and of viscosity on the formation and decay of [special characters omitted]
were also investigated.
To help to distinguish between the above two mechanisms, the zero-charged
novel complex [special characters omitted] (tacn = 1,4,7-triazacyclononane) was synthesized and
characterized. It is thermally stable in aqueous/DMSO solution, but on irradiation at 360
nm undergoes parallel photosubstitution to form DMSO and aqua-substituted products
with an overall quantum yield of 0.012. The product yields increase linearly with added
thiocyanate. For a 1 M thiocyanate solution, the quantum yield for disappearance of the
starting complex rose to 0.022 and a small redox yield of 0.0008 was found. Under these
same conditions, ns laser flash photolysis at 355 nm revealed a transient absorption
owing to [special characters omitted], which was produced with a quantum yield of 0.036. These results are
interpreted in terms of scavenging of radical pair species by thiocyanate ion followed by
back electron transfer to give a photosubstituted product, and a radical pair quantum yield
of 0.29 and lifetime of 12 ps was derived.
The emission of [special characters omitted] (where pop = μ-pyrophosphite-P,P’) can be
quenched by the complexes [special characters omitted] (where X = [special characters omitted]) only
in the presence of electrolytes. The salt effects have been studied using the salts MCl,
M'Cl2, or [special characters omitted] (where M, M’ and R represent alkali, alkaline earth metals, and
alkyl respectively, with n = 0-3), and [special characters omitted]. For 0.5 M cation concentration, second-order quenching rate constants kq lie in the
range [special characters omitted]. For the different quencher complexes used, kq decreases in the
order [special characters omitted]. The oxidative
quenching products [special characters omitted] are observed, and their quantum
yields are 0.083 and 0.027 respectively for the reaction of [special characters omitted] with
[special characters omitted] and [special characters omitted] in 0.5 M KCl / pH2 solution. The quenching occurred
by atom transfer (dominant) and electron transfer (minor) for quencher [special characters omitted] or
[special characters omitted], while only electron transfer was observed for [special characters omitted] and
[special characters omitted] quenchers. The quenching efficiency of the cobalt complexes increases
with electrolyte concentration and specific cation effects are observed in the kq with the
following trends Li+ < Na+ < K+ < Cs+: Mg2+ < Ca2+ < Sr2+ < Ba2+;
NH4+ < MeNH3+ < Me2NH2+ < Me3NH+: Et3NH+ < Et2NH2+ < EtNH3+:
n-PrNH3+ < EtNH3+ < MeNH3+.<br>Graduate
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Yi-KuiHe and 何翊魁. "Effects of quenching environment and thermomechanical treatment on structure and properties of Ti-7.5Mo alloy." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/pabnar.
Full textAbstract:
碩士<br>國立成功大學<br>材料科學及工程學系碩博士班<br>101<br>The first test is about solution treatment by different quenching environment for Ti-7.5Mo alloy, discussed the effect of quench media and the temperature of quench media.The first experiment divided into three parts discussed:Water quenching,and temperture is from W1 to W3℃.Oil quenching, and temperture is from O1 to O4℃. Salt bath quenching, and temperture is form S1 to S3℃.
In the condition of water quenching,yield strength is 533MPa,tensile strength is 864MPa,ductility is 34%,elastic modulus is 80GPa,and crystal structure is α phase.In the condition of oil quenching,yield strength is 610MPa,tensile strength is 890MPa,ductility is 32%,elastic modulus is 85GPa, and crystal structure is α phase. In the condition of salt bath quenching,yield strength is 760MPa,tensile strength is 927MPa,ductility is 21%,elastic modulus is 89GPa, and crystal structure is α phase.
The second test is about fatigue life by different thermomechanical treatment, the fatigue test is strain-controlled fatigue tests used 8%.HRH% ST(S,T2)water quenching,fatigue cycle is 66,648 times.HRH% ST(S,T2) A(A1,T3),fatigue cycle is 29,878 times. HRH% ST(S,T2)CRC%, fatigue cycle is 82,622 times. HRH% ST(S,T2)CRC%A(A2,T3),fatigue cycle is 51,614 times.
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劉煥文. "The Effects of C and Si on Austempering during Quenching Stage of Ductile Irons and Cast Steels." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/08662270388062444575.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>機械工程技術研究所<br>86<br>In this paper the methods of heat treating and metallography were used to study the effects of carbon and silicon content of ductile irons and cast steels on the cooling behavior and phase transformation during quenching period of austempering process. The characteristic of cooling curves and microstructures of ductile irons and cast steels was compared. The results shows that the recalesence was appearing both on the cooling curves of ductile irons and cast steels, the ductile irons austempered at 300℃ had most significant recalesence, and less significance for treated at 400℃. Although the cast steels also had the recalesence when austempered at 300℃, but with a less significant extent, the cast steels showed a high temperature 600~650℃ recalesence when austempered at 400℃. The recalesence appeared around 600~650℃ is induced by the transformation from ausenite but recalesence appared around 300~400℃ is induced by the transformation from austenite to bainite. After austempering, the microstructure of ductile irons and cast steels showed some difference.
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Howard, Brittany. "A comparison of the effects of local and global environment on galaxy evolution in low redshift galaxy clusters." Thesis, 2019. http://hdl.handle.net/1828/11450.
Full textAbstract:
Using the redMaPPer catalog of 21709 galaxy clusters and photometric information for 455946 galaxies from SDSS DR8, we study the effects of local and global environment on galaxy evolution within clusters in the redshift range 0.2 ≤ z ≤ 0.5 and the richness range 20 ≤ λ ≤ 236. We use cluster richness λ as a proxy for global environment and cluster-centric radius dBCG to represent the local environ- ment within clusters. We measure giant-to-dwarf ratio (GDR) which gives insight regarding the composition of the red sequence, and we measure red fraction which holds information about the rate at which galaxies falling into clusters cease to form new stars and build up the red sequence in a phenomenon called quenching. We ob- serve that red fraction decreases with redshift, increases with λ, and decreases with dBCG. GDR, meanwhile, decreases with redshift, does not vary significantly with λ, and decreases with dBCG. All together, our results tell the story of clusters starting with bright, massive galaxies which accrete smaller and smaller galaxies over time. The galaxies are quickly quenched upon entering clusters environment. We observe that most quenching occurs on smaller richness scales than our data covers, and that by the time clusters have grown to the richnesses redMaPPer is sensitive to, ram pressure stripping is likely to be the dominant quenching mechanism.<br>Graduate
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Cheng, Wen-An, and 鄭文安. "Effects of Different Quenching Cooling Rates at Different Temperature Ranges on Impact Toughness of Hot Work Tool Steels." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/18940587566355591274.
Full textAbstract:
碩士<br>國立臺灣大學<br>機械工程學研究所<br>104<br>This study used the steel of JIS SKD61 and the improved steel as experimental materials. The quenching temperature (1020℃) and holding time (1hr) were fixed for quenching at different cooling rates. The cooling process was divided into three stage during quenching, which are the high temperature range (1020℃~700℃), moderate temperature range (700℃~500℃) and low temperature range (500℃~300℃). In order to simulate the actual temperature change in the mold center thicker than 300mm in the field quenching operation, the appropriate quenching cooling rate was reasoned from the CCT curve diagram of various steel grades as the initial condition. The quenching cooling rate of only one temperature interval was changed each time to reduce the cooling rate to 2/3 or 1/2 of initial condition. The quenched sample was tempered to the same target hardness HRC47±_1^(0.5) for impact test to compare the impact values. The microstructure and chemical composition of various samples were analyzed by optical microscope and SEM. The effect of reducing the temperature interval cooling rates on the impact toughness was discussed.
The findings showed that the impact value is most likely to decrease when various types of steel are quenched in the condition of low temperature range cooling rate scale down, and then in the condition of high temperature range cooling rate scale down. The quenching in the condition of moderate temperature range cooling rate scale down has slight effect on the impact value. In addition, if the raw material structure contains considerable and continuous net carbide, as well as considerable macroscopic nonmetallicinclusions (above 20μm), the impact value of the steel containing these structures decreases markedly after quench tempering under various conditions.