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Sample records for non-photochemical quenching process

  1. The structural basis of non-photochemical quenching is revealed?

    Science.gov (United States)

    Cogdell, Richard J

    2006-02-01

    Light-harvesting complex II (LHCII, the major plant light-harvesting pigment-protein complex, efficiently harvests light-energy. However, if the incident light intensity is too high and photosynthesis becomes saturated, LHCII can switch into a quenching state that prevents photodamage. This important process is called non-photochemical quenching, or NPQ, and represents feedback control. Andrew Pascal et al. have recently proposed a detailed model of NPQ based upon the crystal structure of LHCII from spinach.

  2. Non-photochemical fluorescence quenching and the diadinoxanthin cycle in a marine diatom.

    Science.gov (United States)

    Olaizola, M; La Roche, J; Kolber, Z; Falkowski, P G

    1994-08-01

    The diadinoxanthin cycle (DD-cycle) in chromophyte algae involves the interconversion of two carotenoids, diadinoxanthin (DD) and diatoxanthin (DT). We investigated the kinetics of light-induced DD-cycling in the marine diatom Phaeodactylum tricornutum and its role in dissipating excess excitation energy in PS II. Within 15 min following an increase in irradiance, DT increased and was accompanied by a stoichiometric decrease in DD. This reaction was completely blocked by dithiothreitol (DTT). A second, time-dependent, increase in DT was detected ∼ 20 min after the light shift without a concomitant decrease in DD. DT accumulation from both processes was correlated with increases in non-photochemical quenching of chlorophyll fluorescence. Stern-Volmer analyses suggests that changes in non-photochemical quenching resulted from changes in thermal dissipation in the PS II antenna and in the reaction center. The increase in non-photochemical quenching was correlated with a small decrease in the effective absorption cross section of PS II. Model calculations suggest however that the changes in cross section are not sufficiently large to significantly reduce multiple excitation of the reaction center within the turnover time of steady-state photosynthetic electron transport at light saturation. In DTT poisoned cells, the change in non-photochemical quenching appears to result from energy dissipation in the reaction center and was associated with decreased photochemical efficiency. D1 protein degradation was slightly higher in samples poisoned with DTT than in control samples. These results suggest that while DD-cycling may dynamically alter the photosynthesis-irradiance response curve, it offers limited protection against photodamage of PS II reaction centers at irradiance levels sufficient to saturate steady-state photosynthesis.

  3. Non-Photochemical Fluorescence Quenching Across Scales: From Chloroplasts to Plants to Communities

    NARCIS (Netherlands)

    Murchie, E.H.; Harbinson, J.

    2014-01-01

    Non-photochemical quenching (NPQ) of chlorophyll fluorescence, as a measure of photoprotective thermal dissipation of excess excitation energy (from singlet state chlorophyll a), is usually studied at the molecular, organelle, and leaf scale over relatively short time periods, where it is most readi

  4. Non-photochemical quenching in cryptophyte alga Rhodomonas salina is located in chlorophyll a/c antennae.

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    Kaňa, Radek; Kotabová, Eva; Sobotka, Roman; Prášil, Ondřej

    2012-01-01

    Photosynthesis uses light as a source of energy but its excess can result in production of harmful oxygen radicals. To avoid any resulting damage, phototrophic organisms can employ a process known as non-photochemical quenching (NPQ), where excess light energy is safely dissipated as heat. The mechanism(s) of NPQ vary among different phototrophs. Here, we describe a new type of NPQ in the organism Rhodomonas salina, an alga belonging to the cryptophytes, part of the chromalveolate supergroup. Cryptophytes are exceptional among photosynthetic chromalveolates as they use both chlorophyll a/c proteins and phycobiliproteins for light harvesting. All our data demonstrates that NPQ in cryptophytes differs significantly from other chromalveolates - e.g. diatoms and it is also unique in comparison to NPQ in green algae and in higher plants: (1) there is no light induced xanthophyll cycle; (2) NPQ resembles the fast and flexible energetic quenching (qE) of higher plants, including its fast recovery; (3) a direct antennae protonation is involved in NPQ, similar to that found in higher plants. Further, fluorescence spectroscopy and biochemical characterization of isolated photosynthetic complexes suggest that NPQ in R. salina occurs in the chlorophyll a/c antennae but not in phycobiliproteins. All these results demonstrate that NPQ in cryptophytes represents a novel class of effective and flexible non-photochemical quenching.

  5. Non-photochemical quenching in cryptophyte alga Rhodomonas salina is located in chlorophyll a/c antennae.

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    Radek Kaňa

    Full Text Available Photosynthesis uses light as a source of energy but its excess can result in production of harmful oxygen radicals. To avoid any resulting damage, phototrophic organisms can employ a process known as non-photochemical quenching (NPQ, where excess light energy is safely dissipated as heat. The mechanism(s of NPQ vary among different phototrophs. Here, we describe a new type of NPQ in the organism Rhodomonas salina, an alga belonging to the cryptophytes, part of the chromalveolate supergroup. Cryptophytes are exceptional among photosynthetic chromalveolates as they use both chlorophyll a/c proteins and phycobiliproteins for light harvesting. All our data demonstrates that NPQ in cryptophytes differs significantly from other chromalveolates - e.g. diatoms and it is also unique in comparison to NPQ in green algae and in higher plants: (1 there is no light induced xanthophyll cycle; (2 NPQ resembles the fast and flexible energetic quenching (qE of higher plants, including its fast recovery; (3 a direct antennae protonation is involved in NPQ, similar to that found in higher plants. Further, fluorescence spectroscopy and biochemical characterization of isolated photosynthetic complexes suggest that NPQ in R. salina occurs in the chlorophyll a/c antennae but not in phycobiliproteins. All these results demonstrate that NPQ in cryptophytes represents a novel class of effective and flexible non-photochemical quenching.

  6. Increased biomass productivity in green algae by tuning non-photochemical quenching

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    Berteotti, Silvia; Ballottari, Matteo; Bassi, Roberto

    2016-01-01

    Photosynthetic microalgae have a high potential for the production of biofuels and highly valued metabolites. However, their current industrial exploitation is limited by a productivity in photobioreactors that is low compared to potential productivity. The high cell density and pigment content of the surface layers of photosynthetic microalgae result in absorption of excess photons and energy dissipation through non-photochemical quenching (NPQ). NPQ prevents photoinhibition, but its activation reduces the efficiency of photosynthetic energy conversion. In Chlamydomonas reinhardtii, NPQ is catalyzed by protein subunits encoded by three lhcsr (light harvesting complex stress related) genes. Here, we show that heat dissipation and biomass productivity depends on LHCSR protein accumulation. Indeed, algal strains lacking two lhcsr genes can grow in a wide range of light growth conditions without suffering from photoinhibition and are more productive than wild-type. Thus, the down-regulation of NPQ appears to be a suitable strategy for improving light use efficiency for biomass and biofuel production in microalgae. PMID:26888481

  7. Ecophysiology of photosynthesis in bryophytes: major roles for oxygen photoreduction and non-photochemical quenching?

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    Proctor, Michael C F; Smirnoff, Nicholas

    2011-02-01

    CO(2) fixation in mosses saturates at moderate irradiances. Relative electron transport rate (RETR) inferred from chlorophyll fluorescence saturates at similar irradiance in shade species (e.g. Plagiomnium undulatum, Trichocolea tomentella), but many species of unshaded habitats (e.g. Andreaea rothii, Schistidium apocarpum, Sphagnum spp. and Frullania dilatata) show non-saturating RETR at high irradiance, with high non-photochemical quenching (NPQ). In P. undulatum and S. apocarpum, experiments in different gas mixtures showed O(2) and CO(2) as interchangeable electron sinks. Nitrogen + saturating CO(2) gave high RETR and depressed NPQ. In S. apocarpum, glycolaldehyde (inhibiting photosynthesis and photorespiration) depressed RETR in air more at low than at high irradiance; in CO(2) -free air RETR was maintained at all irradiances. Non-saturating electron flow was not suppressed in ambient CO(2) with 1% O(2) . The results indicate high capacity for oxygen photoreduction when CO(2) assimilation is limited. Non-saturating light-dependent H(2) O(2) production, insensitive to glycolaldehyde, suggests that electron transport is supported by oxygen photoreduction, perhaps via the Mehler-peroxidase reaction. Consistent with this, mosses were highly tolerant to paraquat, which generates superoxide at photosystem I (PSI). Protection against excess excitation energy in mosses involves high capacity for photosynthetic electron transport to oxygen and high NPQ, activated at high irradiance, alongside high reactive oxygen species (ROS) tolerance.

  8. Arctic Micromonas uses protein pools and non-photochemical quenching to cope with temperature restrictions on Photosystem II protein turnover.

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    Ni, Guangyan; Zimbalatti, Gabrielle; Murphy, Cole D; Barnett, Audrey B; Arsenault, Christopher M; Li, Gang; Cockshutt, Amanda M; Campbell, Douglas A

    2017-02-01

    Micromonas strains of small prasinophyte green algae are found throughout the world's oceans, exploiting widely different niches. We grew arctic and temperate strains of Micromonas and compared their susceptibilities to photoinactivation of Photosystem II, their counteracting Photosystem II repair capacities, their Photosystem II content, and their induction and relaxation of non-photochemical quenching. In the arctic strain Micromonas NCMA 2099, the cellular content of active Photosystem II represents only about 50 % of total Photosystem II protein, as a slow rate constant for clearance of PsbA protein limits instantaneous repair. In contrast, the temperate strain NCMA 1646 shows a faster clearance of PsbA protein which allows it to maintain active Photosystem II content equivalent to total Photosystem II protein. Under growth at 2 °C, the arctic Micromonas maintains a constitutive induction of xanthophyll deepoxidation, shown by second-derivative whole-cell spectra, which supports strong induction of non-photochemical quenching under low to moderate light, even if xanthophyll cycling is blocked. This non-photochemical quenching, however, relaxes during subsequent darkness with kinetics nearly comparable to the temperate Micromonas NCMA 1646, thereby limiting the opportunity cost of sustained downregulation of PSII function after a decrease in light.

  9. LHC II protein phosphorylation in leaves of Arabidopsis thaliana mutants deficient in non-photochemical quenching.

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    Breitholtz, Hanna-Leena; Srivastava, Renu; Tyystjärvi, Esa; Rintamäki, Eevi

    2005-06-01

    Phosphorylation of the light-harvesting chlorophyll a/b complex II (LHC II) proteins is induced in light via activation of the LHC II kinase by reduction of cytochrome b(6)f complex in thylakoid membranes. We have recently shown that, besides this activation, the LHC II kinase can be regulated in vitro by a thioredoxin-like component, and H2O2 that inserts an inhibitory loop in the regulation of LHC II protein phosphorylation in the chloroplast. In order to disclose the complex network for LHC II protein phosphorylation in vivo, we studied phosphorylation of LHC II proteins in the leaves of npq1-2 and npq4-1 mutants of Arabidopis thaliana. In comparison to wild-type, these mutants showed reduced non-photochemical quenching and increased excitation pressure of Photosystem II (PS II) under physiological light intensities. Peculiar regulation of LHC II protein phosphorylation was observed in mutant leaves under illumination. The npq4-1 mutant was able to maintain a high amount of phosphorylated LHC II proteins in thylakoid membranes at light intensities that induced inhibition of phosphorylation in wild-type leaves. Light intensity-dependent changes in the level of LHC II protein phosphorylation were smaller in the npq1-2 mutant compared to the wild-type. No significant differences in leaf thickness, dry weight, chlorophyll content, or the amount of LHC II proteins were observed between the two mutant and wild-type lines. We propose that the reduced capacity of the mutant lines to dissipate excess excitation energy induces changes in the production of reactive oxygen species in chloroplasts, which consequently affects the regulation of LHC II protein phosphorylation.

  10. Light-induced dissociation of an antenna hetero-oligomer is needed for non-photochemical quenching induction.

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    Betterle, Nico; Ballottari, Matteo; Zorzan, Simone; de Bianchi, Silvia; Cazzaniga, Stefano; Dall'osto, Luca; Morosinotto, Tomas; Bassi, Roberto

    2009-05-29

    PsbS plays a major role in activating the photoprotection mechanism known as "non-photochemical quenching," which dissipates chlorophyll excited states exceeding the capacity for photosynthetic electron transport. PsbS activity is known to be triggered by low lumenal pH. However, the molecular mechanism by which this subunit regulates light harvesting efficiency is still unknown. Here we show that PsbS controls the association/dissociation of a five-subunit membrane complex, composed of two monomeric Lhcb proteins (CP29 and CP24) and the trimeric LHCII-M. Dissociation of this supercomplex is indispensable for the onset of non-photochemical fluorescence quenching in high light, strongly suggesting that protein subunits catalyzing the reaction of heat dissipation are buried into the complex and thus not available for interaction with PsbS. Consistently, we showed that knock-out mutants on two subunits participating to the B4C complex were strongly affected in heat dissipation. Direct observation by electron microscopy and image analysis showed that B4C dissociation leads to the redistribution of PSII within grana membranes. We interpreted these results to mean that the dissociation of B4C makes quenching sites, possibly CP29 and CP24, available for the switch to an energy-quenching conformation. These changes are reversible and do not require protein synthesis/degradation, thus allowing for changes in PSII antenna size and adaptation to rapidly changing environmental conditions.

  11. O2-dependent electron flow, membrane energization and the mechanism of non-photochemical quenching of chlorophyll fluorescence.

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    Schreiber, U; Neubauer, C

    1990-09-01

    Recent progress in chlorophyll fluorescence research is reviewed, with emphasis on separation of photochemical and non-photochemical quenching coefficients (qP and qN) by the 'saturation pulse method'. This is part of an introductory talk at the Wageningen Meeting on 'The use of chlorophyll fluorescence and other non-invasive techniques in plant stress physiology'. The sequence of events is investigated which leads to down-regulation of PS II quantum yield in vivo, expressed in formation of qN. The role of O2-dependent electron flow for ΔpH- and qN-formation is emphasized. Previous conclusions on the rate of 'pseudocyclic' transport are re-evaluated in view of high ascorbate peroxidase activity observed in intact chloroplasts. It is proposed that the combined Mehler-Peroxidase reaction is responsible for most of the qN developed when CO2-assimilation is limited. Dithiothreitol is shown to inhibit part of qN-formation as well as peroxidase-induced electron flow. As to the actual mechanism of non-photochemical quenching, it is demonstrated that quenching is favored by treatments which slow down reactions at the PS II donor side. The same treatments are shown to stimulate charge recombination, as measured via 50 μs luminescence. It is suggested that also in vivo internal thylakoid acidification leads to stimulation of charge recombination, although on a more rapid time scale. A unifying model is proposed, incorporating reaction center and antenna quenching, with primary control of ΔpH at the PS II reaction center, involving radical pair spin transition and charge recombination to the triplet state in a first quenching step. In a second step, triplet excitation is trapped by zeaxanthin (if present) which in its triplet excited state causes additional quenching of singlet excited chlorophyll.

  12. Exogenous Melatonin Mitigates Photoinhibition by Accelerating Non-photochemical Quenching in Tomato Seedlings Exposed to Moderate Light during Chilling

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    Ding, Fei; Wang, Meiling; Liu, Bin; Zhang, Shuoxin

    2017-01-01

    Melatonin plays an important role in tolerance to multiple stresses in plants. Recent studies have shown that melatonin relieves photoinhibition in plants under cold stress; however, the mechanisms are not fully understood. Non-photochemical quenching (NPQ) is a key process thermally dissipating excess light energy that plants employ as a protective mechanism to prevent the over reduction of photosystem II. Here, we report the effects of exogenous melatonin on NPQ and mitigation of photoinhibition in tomato seedlings exposed to moderate light during chilling. In response to moderate light during chilling, the maximum quantum yield (Fv/Fm) and the effective photochemical efficiency (F′v/F′m) of PSII were both substantially reduced, showing severe photoinhibition in tomato seedlings, whereas exogenous application of melatonin effectively alleviated the photoinhibition. Further experiment showed that melatonin accelerated the induction of NPQ in response to moderate light and maintained higher level of NPQ upon longer exposure to light during chilling. Consistent with the increased NPQ was the elevated de-epoxidation state of xanthophyll pigments in melatonin-pretreated seedlings exposed to light during chilling. Enzyme activity assay showed that violaxanthin de-epoxidase (VDE), which catalyzes the de-epoxidation reaction in the xanthophyll cycle, was activated by light and the activity was further enhanced by application of melatonin. Further analysis revealed that melatonin induced the expression of VDE gene in tomato seedlings under moderate light and chilling conditions. Ascorbic acid is an essential cofactor of VDE and the level of it was found to be increased in melatonin-pretreated seedlings. Feeding tomato seedlings with dithiothreitol, an inhibitor of VDE, blocked the effects of melatonin on the de-epoxidation state of xanthophyll pigments and the induction of NPQ. Collectively, these results suggest that exogenous melatonin mitigates photoinhibition by

  13. Light harvesting and blue-green light induced non-photochemical quenching in two different C-phycocyanin mutants of Synechocystis PCC 6803.

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    Tian, Lijin; van Stokkum, Ivo H M; Koehorst, Rob B M; van Amerongen, Herbert

    2013-09-26

    Cyanobacteria are oxygen-evolving photosynthetic organisms that harvest sunlight and convert excitation energy into chemical energy. Most of the light is absorbed by large light harvesting complexes called phycobilisomes (PBs). In high-light conditions, cyanobacteria switch on a photoprotective mechanism called non-photochemical quenching (NPQ): During this process, absorption of blue-green light transforms the inactive orange form of the orange carotenoid protein OCP (OCP(o)) into the red active form OCP(r) that subsequently binds to the PB, resulting in a substantial loss of excitation energy and corresponding decrease of the fluorescence. In wild-type cells, the quenching site is a bilin chomophore that fluoresces at 660 nm and which is called APC(Q)(660). In the present work, we studied NPQ in two different types of mutant cells (CB and CK) that possess significantly truncated PBs, using spectrally resolved picosecond fluorescence spectroscopy. The results are in very good agreement with earlier in vitro experiments on quenched and unquenched PBs, although the fraction of quenched PBs is far lower in vivo. It is also lower than the fraction of PBs that is quenched in wild-type cells, but the site, rate, and location of quenching appear to be very similar.

  14. A mathematical model of non-photochemical quenching to study short-term light memory in plants.

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    Matuszyńska, Anna; Heidari, Somayyeh; Jahns, Peter; Ebenhöh, Oliver

    2016-12-01

    Plants are permanently exposed to rapidly changing environments, therefore it is evident that they had to evolve mechanisms enabling them to dynamically adapt to such fluctuations. Here we study how plants can be trained to enhance their photoprotection and elaborate on the concept of the short-term illumination memory in Arabidopsis thaliana. By monitoring fluorescence emission dynamics we systematically observe the extent of non-photochemical quenching (NPQ) after previous light exposure to recognise and quantify the memory effect. We propose a simplified mathematical model of photosynthesis that includes the key components required for NPQ activation, which allows us to quantify the contribution to photoprotection by those components. Due to its reduced complexity, our model can be easily applied to study similar behavioural changes in other species, which we demonstrate by adapting it to the shadow-tolerant plant Epipremnum aureum. Our results indicate that a basic mechanism of short-term light memory is preserved. The slow component, accumulation of zeaxanthin, accounts for the amount of memory remaining after relaxation in darkness, while the fast one, antenna protonation, increases quenching efficiency. With our combined theoretical and experimental approach we provide a unifying framework describing common principles of key photoprotective mechanisms across species in general, mathematical terms.

  15. Canopy-Level Photochemical Reflectance Index from Hyperspectral Remote Sensing and Leaf-Level Non-Photochemical Quenching as Early Indicators of Water Stress in Maize

    Directory of Open Access Journals (Sweden)

    Shuren Chou

    2017-08-01

    Full Text Available In this study, we evaluated the effectiveness of photochemical reflectance index (PRI and non-photochemical quenching (NPQ for assessing water stress in maize for the purpose of developing remote sensing techniques for monitoring water deficits in crops. Leaf-level chlorophyll fluorescence and canopy-level PRI were measured concurrently over a maize field with five different irrigation treatments, ranging from 20% to 90% of the field capacity (FC. Significant correlations were found between leaf-level NPQ (NPQleaf and the ratio of chlorophyll to carotenoid content (Chl/Car (R2 = 0.71, p < 0.01 and between NPQleaf and the actual photochemical efficiency of photosystem II (ΔF/Fm′ (R2 = 0.81, p < 0.005. At the early growing stage, both canopy-level PRI and NPQleaf are good indicators of water stress (R2 = 0.65 and p < 0.05; R2 = 0.63 and p < 0.05, respectively. For assessment of extreme water stress on plant growth, a relationship is also established between the quantum yield of photochemistry in PSII (ΦP and the quantum yield of fluorescence (ΦF as determined from photochemical quenching (PQ and non-photochemical quenching (NPQleaf of excitation energy at different water stress levels. These results would be helpful in monitoring soil water stress on crops at large scales using remote sensing techniques.

  16. Arbuscular mycorrhizal symbiosis ameliorates the optimum quantum yield of photosystem II and reduces non-photochemical quenching in rice plants subjected to salt stress.

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    Porcel, Rosa; Redondo-Gómez, Susana; Mateos-Naranjo, Enrique; Aroca, Ricardo; Garcia, Rosalva; Ruiz-Lozano, Juan Manuel

    2015-08-01

    Rice is the most important food crop in the world and is a primary source of food for more than half of the world population. However, salinity is considered the most common abiotic stress reducing its productivity. Soil salinity inhibits photosynthetic processes, which can induce an over-reduction of the reaction centres in photosystem II (PSII), damaging the photosynthetic machinery. The arbuscular mycorrhizal (AM) symbiosis may improve host plant tolerance to salinity, but it is not clear how the AM symbiosis affects the plant photosynthetic capacity, particularly the efficiency of PSII. This study aimed at determining the influence of the AM symbiosis on the performance of PSII in rice plants subjected to salinity. Photosynthetic activity, plant gas-exchange parameters, accumulation of photosynthetic pigments and rubisco activity and gene expression were also measured in order to analyse comprehensively the response of the photosynthetic processes to AM symbiosis and salinity. Results showed that the AM symbiosis enhanced the actual quantum yield of PSII photochemistry and reduced the quantum yield of non-photochemical quenching in rice plants subjected to salinity. AM rice plants maintained higher net photosynthetic rate, stomatal conductance and transpiration rate than nonAM plants. Thus, we propose that AM rice plants had a higher photochemical efficiency for CO2 fixation and solar energy utilization and this increases plant salt tolerance by preventing the injury to the photosystems reaction centres and by allowing a better utilization of light energy in photochemical processes. All these processes translated into higher photosynthetic and rubisco activities in AM rice plants and improved plant biomass production under salinity.

  17. Silencing of the violaxanthin de-epoxidase gene in the diatom Phaeodactylum tricornutum reduces diatoxanthin synthesis and non-photochemical quenching.

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    Johann Lavaud

    Full Text Available Diatoms are a major group of primary producers ubiquitous in all aquatic ecosystems. To protect themselves from photooxidative damage in a fluctuating light climate potentially punctuated with regular excess light exposures, diatoms have developed several photoprotective mechanisms. The xanthophyll cycle (XC dependent non-photochemical chlorophyll fluorescence quenching (NPQ is one of the most important photoprotective processes that rapidly regulate photosynthesis in diatoms. NPQ depends on the conversion of diadinoxanthin (DD into diatoxanthin (DT by the violaxanthin de-epoxidase (VDE, also called DD de-epoxidase (DDE. To study the role of DDE in controlling NPQ, we generated transformants of P. tricornutum in which the gene (Vde/Dde encoding for DDE was silenced. RNA interference was induced by genetic transformation of the cells with plasmids containing either short (198 bp or long (523 bp antisense (AS fragments or, alternatively, with a plasmid mediating the expression of a self-complementary hairpin-like construct (inverted repeat, IR. The silencing approaches generated diatom transformants with a phenotype clearly distinguishable from wildtype (WT cells, i.e. a lower degree as well as slower kinetics of both DD de-epoxidation and NPQ induction. Real-time PCR based quantification of Dde transcripts revealed differences in transcript levels between AS transformants and WT cells but also between AS and IR transformants, suggesting the possible presence of two different gene silencing mediating mechanisms. This was confirmed by the differential effect of the light intensity on the respective silencing efficiency of both types of transformants. The characterization of the transformants strengthened some of the specific features of the XC and NPQ and confirmed the most recent mechanistic model of the DT/NPQ relationship in diatoms.

  18. Temperature dependence of violaxanthin de-epoxidation and non-photochemical fluorescence quenching in intact leaves of Gossypium hirsutum L. and Malva parviflora L.

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    Bilger, W; Björkman, O

    1991-05-01

    The temperature dependence of the rate of de-epoxidation of violaxanthin to zeaxanthin was determined in leaves of chilling-sensitive Gossypium hirsutum L. (cotton) and chilling-resistant Malva parviflora L. by measurements of the increase in absorbance at 505 nm (ΔA 505) and in the contents of antheraxanthin and zeaxanthin that occur upon exposure of predarkened leaves to excessive light. A linear relationship between ΔA 505 and the decrease in the epoxidation state of the xanthophyll-cycle pigment pool was obtained over the range 10-40° C. The maximal rate of de-epoxidation was strongly temperature dependent; Q10 measured around the temperature at which the leaf had developed was 2.1-2.3 in both species. In field-grown Malva the rate of de-epoxidation at any given measurement temperature was two to three times higher in leaves developed at a relatively low temperature in the early spring than in those developed in summer. Q10 measured around 15° C was in the range 2.2-2.6 in both kinds of Malva leaves, whereas it was as high as 4.6 in cotton leaves developed at a daytime temperature of 30° C. Whereas the maximum (initial) rate of de-epoxidation showed a strong decrease with decreased temperature the degree of de-epoxidation reached in cotton leaves after a 1-2 · h exposure to a constant photon flux density increased with decreased temperature as the rate of photosynthesis decrease. The zeaxanthin content rose from 2 mmol · (mol chlorophyll)(-1) at 30° C to 61 mmol · (mol Chl)(-1) at 10° C, corresponding to a de-epoxidation of 70% of the violaxanthin pool at 10° C. The degree of de-epoxidation at each temperature was clearly related to the amount of excessive light present at that temperature. The relationship between non-photochemical quenching of chlorophyll fluorescence and zeaxanthin formation at different temperatures was determined for both untreated control leaves and for leaves in which zeaxanthin formation was prevented by dithiothreitol

  19. Responses to desiccation stress in bryophytes and an important role of dithiothreitol-insensitive non-photochemical quenching against photoinhibition in dehydrated states.

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    Nabe, Hayase; Funabiki, Ryoko; Kashino, Yasuhiro; Koike, Hiroyuki; Satoh, Kazuhiko

    2007-11-01

    The effects of air drying and hypertonic treatments in the dark on seven bryophytes, which had grown under different water environments, were studied. All the desiccation-tolerant species tested lost most of their PSII photochemical activity when photosynthetic electron transport was inhibited by air drying, while, in all the sensitive species, the PSII photochemical activity remained at a high level even when photosynthesis was totally inhibited. The PSI reaction center remained active under drying conditions in both sensitive and tolerant species, but the activity became non-detectable in the light only in tolerant species due to deactivation of the cyclic electron flow around PSI and of the back reaction in PSI. Light-induced non-photochemical quenching (NPQ) was found to be induced not only by the xanthophyll cycle but also by a DeltapH-induced, dithiothreitol-insensitive mechanism in both the desiccation-tolerant and -intolerant bryophytes. Both mechanisms are thought to have an important role in protecting desiccation-tolerant species from photoinhibition under drying conditions. Fluorescence emission spectra at 77K showed that dehydration-induced quenching of PSII fluorescence was observed only in tolerant species and was due to neither state 1-state 2 transition nor detachment of light-harvesting chlorophyll protein complexes from PSII core complexes. The presence of dehydration-induced quenching of PSI fluorescence was also suggested.

  20. Roles of the transthylakoid proton gradient and xanthophyll cycle in the non-photochemical quenching of the green alga Ulva linza

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    Zhang, Xiaowen; Mou, Shanli; Cao, Shaona; Fan, Xiao; Xu, Dong; Ye, Naihao

    2015-09-01

    Non-photochemical quenching (NPQ) is one of the most important photoprotection mechanisms in photosynthetic organisms when they are exposed to excessive irradiation. The basic principle of NPQ, which is the safe dissipation of excessive absorbed light as heat, is identical in all photoautotrophs. However, crucial differences in its regulation and structural mechanisms exist in different phototrophs. Here, we investigated NPQ in the green alga Ulva linza coupled with inhibitors to alter the amplitude of the transthylakoid proton gradient (ΔpH) and/or de-expoxidation of xanthophyll cycle (XC) under high light conditions. The data demonstrates that NPQ started with a rapid initial rise within the first minute of illumination, followed by a decline before a further rise in quenching. During the whole phase, NPQ was triggered and completely controlled by ΔpH, then strengthened and modulated by zeaxanthin. NPQ relaxation was slower in U. linza when compared to plants and other green algae, and it may be mainly caused by the slow conversion of zeaxanthin to violaxanthin. NPQ in U. linza is controlled to a greater extent by XC, which show more similarities to Arabidopsis than to Chlamydomonas and may be an adaptive mechanism for its successful colonization of coastal ecosystems.

  1. Relationship between xanthophyll cycle and non-photochemical quenching in rice (Oryza sativa L.) plants in response to light stress.

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    Vaz, Janet; Sharma, Prabhat K

    2011-01-01

    Thirty days old rice plants grown under low and moderate light conditions were transferred to full sunlight to observe the extent of photoinhibitory damage and protective mechanism, and the relationship between xanthophyll cycle and nonphotochemical quenching (qN) under changing light environment. Control plants (low, moderate and sun grown) exhibited similar Fv/Fm ratio, indicating similar photosynthetic efficiency prior to light stress. On exposure to the high light treatment, low light grown plants exhibited faster and higher degree of photoinhibition compared to moderate and high light grown plants. Moderate and high light grown plants showed relatively less photoinhibition and also showed higher qN, indicating better capacity of energy dissipation. Increase in qN in moderate light and sun grown plants was accompanied by conversion of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) indicating operation of Z-dependent thermal dissipation. Rice plants fed with ascorbate (AsA), a stimulator of the de-epoxidation state of V to Z, showed higher Fv/Fm ratio and qN than the plants fed with dithiothreitol (DTT) an inhibitor of xanthophyll cycle. This indicated that an increased amount of energy reached PS II reaction centre, due to absence of A and Z formation, thereby causing greater damage to photosynthesis in DTT fed rice plants. The present data confirmed the relationship between qN and Z in dissipating the excess light energy, thereby protecting plants against photodamage.

  2. Multi-Level, Multi Time-Scale Fluorescence Intermittency of Photosynthetic LH2 Complexes: A Precursor of Non-Photochemical Quenching?

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    Schörner, Mario; Beyer, Sebastian Reinhardt; Southall, June; Cogdell, Richard J; Köhler, Jürgen

    2015-11-01

    The light harvesting complex LH2 is a chromoprotein that is an ideal system for studying protein dynamics via the spectral fluctuations of the emission of its intrinsic chromophores. We have immobilized these complexes in a polymer film and studied the fluctuations of the fluorescence intensity from individual complexes over 9 orders of magnitude in time. Combining time-tagged detection of single photons with a change-point analysis has allowed the unambigeous identification of the various intensity levels due to the huge statistical basis of the data set. We propose that the observed intensity level fluctuations reflect conformational changes of the protein backbone that might be a precursor of the mechanism from which nonphotochemical quenching of higher plants has evolved.

  3. Integrating transient heterogeneity of non-photochemical quenching in shade-grown heterobaric leaves of avocado (Persea americana L.): responses to CO2 concentration, stomatal occlusion, dehydration and relative humidity.

    Science.gov (United States)

    Takayama, Kotaro; King, Diana; Robinson, Sharon A; Osmond, Barry

    2013-11-01

    Long-lived shade leaves of avocado had extremely low rates of photosynthesis. Gas exchange measurements of photosynthesis were of limited use, so we resorted to Chl fluorescence imaging (CFI) and spot measurements to evaluate photosynthetic electron transport rates (ETRs) and non-photochemical quenching (NPQ). Imaging revealed a remarkable transient heterogeneity of NPQ during photosynthetic induction in these hypostomatous, heterobaric leaves, but was adequately integrated by spot measurements, despite long-lasting artifacts from repeated saturating flashes during assays. Major veins (mid-vein, first- and second-order veins) defined areas of more static large-scale heterogeneous NPQ, with more dynamic small-scale heterogeneity most strongly expressed in mesophyll cells between third- and fourth-order veins. Both responded to external CO2 concentration ([CO2]), occlusion of stomata with Vaseline™, leaf dehydration and relative humidity (RH). We interpreted these responses in terms of independent behavior of stomata in adjacent areoles that was largely expressed through CO2-limited photosynthesis. Heterogeneity was most pronounced and prolonged in the absence of net CO2 fixation in 100 p.p.m. [CO2] when respiratory and photorespiratory CO2 cycling constrained the inferred ETR to ~75% of values in 400 or 700 p.p.m. [CO2]. Likewise, sustained higher NPQ under Vaseline™, after dehydration or at low RH, also restricted ETR to ~75% of control values. Low NPQ in chloroplast-containing cells adjacent to major veins but remote from stomata suggested internal sources of high [CO2] in these tissues.

  4. Design of Industrial Quenching Processes

    Institute of Scientific and Technical Information of China (English)

    Nikolai. I. KOBASKO; George .E. TOTTEN

    2004-01-01

    The method of designing industrial processes of quench cooling, in particular, the speed of the conveyor movement with regard to shape and sizes of parts to be quenched, thermal and physical properties of material and cooling capacity of quenchants has been developed. The suggested designing method and databases are the basis for the complete automation of industrial processes of quench cooling, especially for continuous conveyor lines, with the purpose of making high-strength materials. The process is controlled by infrared technique.

  5. Effects of Water Stress on Photochemical Quenching and Non-photochemical Quenching of Chlorophyll a Fluorescence in Four Tree Seedlings%水分胁迫对4种苗木叶绿素荧光的光化学淬灭和非光化学淬灭的影响

    Institute of Scientific and Technical Information of China (English)

    史胜青; 袁玉欣; 杨敏生; 梁海永; 张金香

    2004-01-01

    The changes of photochemical quenching(qp) and non-photochemical quenching(qN) of chlorophyll a fluorescence in leaves of four tree seedlings ( Gleditsia sinensis, Juglans regia, Diospyros kaki and Diospyros lotus ) were different between two different water stress ways:detached drought treatment and potted drought treatment. After 4 hours dehydration by leaf detaching,the qp values had significant decrease except J. regia, only 6 hours later, the qp values compared with contrast decreased significantly in four tree seedlings(P>0.05), but the range of reduction( G.sinensis, J.regia and D.lotus) was just 2.5% to 6.4%. D.kaki, however,got to 31.3%. While the qN values increased significantly with conducting dehydration of the detached leaves. However, the qp values of four species showed no significant decrease when they were growing in pots under soil water stress(40%~60% RWC) for 30 days; and the qN values decreased obviously with a exception in J. regia, which was consistent with that of detached leaf treatment. The results suggested that some difference or changes in mechanism of excess light energy dissipation might perform in four seedlings by short-term and long-term water stress.

  6. ΔpH-dependent non-photochemical quenching (qE) of excited chlorophylls in the photosystem II core complex of the freshwater cyanobacterium Synechococcus sp PCC 7942.

    Science.gov (United States)

    Stamatakis, Kostas; Papageorgiou, George C

    2014-08-01

    Light-induced and lumen acidity-dependent quenching (qE) of excited chlorophylls (Chl) in vivo has been amply documented in plants and algae, but not in cyanobacteria, using primarily the saturation pulse method of quenching analysis which is applied to continuously illuminated samples. This method is unsuitable for cyanobacteria because the background illumination elicits in them a very large Chl a fluorescence signal, due to a state 2 to state 1 transition, which masks fluorescence changes due to other causes. We investigated the qE problem in the cyanobacterium Synechococcus sp. PCC 7942 using a kinetic method (Chl a fluorescence induction) with which qE can be examined before the onset of the state 2 to state 1 transition and the attendant rise of Chl a fluorescence. Our results confirm the existence of a qE mechanism that operates on excited Chls a in Photosystem II core complexes of cyanobacteria.

  7. Characterization of non-photochemically formed oligomers from methylglyoxal: a pathway to produce secondary organic aerosol through cloud processing during night-time

    Directory of Open Access Journals (Sweden)

    F. Yasmeen

    2009-10-01

    Full Text Available Aqueous-phase oligomer formation from methylglyoxal, a major atmospheric photooxidation product, has been investigated in a simulated cloud matrix under dark conditions. The aim of this study was to explore an additional path producing secondary organic aerosol (SOA through cloud processes without photochemistry during night-time. Indeed, atmospheric models still underestimate SOA formation, as field measurements have revealed more SOA than predicted. Soluble oligomers (n=1–8 formed in the course of acid-catalyzed aldol condensation and acid-catalyzed hydration followed by acetal formation have been detected and characterized by positive and negative ion electrospray ionization mass spectrometry. Aldol condensation proved to be a favorable mechanism under simulated cloud conditions, while hydration/acetal formation was found to strongly depend on the pH of the system. The aldol oligomer series starts with a β-hydroxy ketone via aldol condensation, where oligomers are formed by multiple additions of C3H4O2 units (72 Da to the parent β-hydroxy ketone. Ion trap mass spectrometry experiments were performed to structurally characterize the major oligomer species. A mechanistic pathway for the growth of oligomers under cloud conditions and in the absence of UV-light and OH radicals, which could substantially enhance in-cloud SOA yields, is proposed here for the first time.

  8. Thermal quenching of luminescence processes in feldspars

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Duller, G.A.T.

    1995-01-01

    The technique of optically stimulated luminescence has important uses in the dose evaluation of irradiated feldspars. The luminescence process involves the eviction of electrons from donor traps, charge transfer through the conduction band, and recombination at acceptor sites; each...... of these processes is, in general, thermally dependent, and leads either to enhancement or quenching of the luminescence with increasing temperature. Previous studies have measured the combined thermal activation characteristics of all three processes, and show a strong dependence on stimulation energy....... In this article, an initial attempt is made to isolate only the recombination part of the luminescence cycle, and determine its thermal characteristics separately. A Variety of luminescence transitions are examined in a range of both alkali and plagioclase feldspars; three distinct emission types are identified...

  9. Flame quenching process in cavity based on model scramjet combustor

    Institute of Scientific and Technical Information of China (English)

    Yu Pan; Jing Lei; Jian-Han Liang; Wei-Dong Liu; Zhen-Guo Wang

    2012-01-01

    The flame quenching process in combustors was observed by high speed camera and Schlieren system,at the inflow conditions of Ma =2.64,To =1 483 K,P0 =1.65 MPa,T =724 K and P =76.3 kPa.Changing process of the flame and shock structure in the combustor was clearly observed.The results revealed that the precombustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while.The rime of quenching process was extended by the cavity flame holder,and the ability of flame holding was enhanced by arranging more cavities in the downstream as well.The flame was blown from the upstream to the downstream,so the flame in the downstream of the cavity was quenched out later than that in the upstream.

  10. A New Quenching Process and Tower to Improve the Recovery of Acrylonitrile

    Institute of Scientific and Technical Information of China (English)

    甘永胜; 顾军民; 方永成

    2004-01-01

    Quenching process and design of the quenching tower in acrylonitrile production in China were studied in order to decrease the polymerization loss of acrylonitrile in the quenching tower. Based on the research of acrylonitrile polymerization in the quenching tower, a new quenching process was proposed to avoid the disadvantages of the original process. Two kinds of internals were installed to improve the performance of the quenching tower. Through a series of air-flow and real-flow model experiments, the new quenching process and new design were showed to be successful in enhancing the mass and heat transfer in the vapor-liquid system and decreasing the loss of acrylonitrile.Industrial application showed satisfactory results of decrease of the acrylonitrile loss in the quenching tower by about 4.5% and increase of the acrylonitrile recovery of the whole plant by more than 4%.

  11. The "quenching and partitioning" process: background and recent progress

    Directory of Open Access Journals (Sweden)

    John G. Speer

    2005-12-01

    Full Text Available A new process concept, "quenching and partitioning" (Q&P has been proposed recently for creating steel microstructures with retained austenite. The process involves quenching austenite below the martensite-start temperature, followed by a partitioning treatment to enrich the remaining austenite with carbon, thereby stabilizing it to room temperature. The process concept is reviewed here, along with the thermodynamic basis for the partitioning treatment, and a model for designing some of the relevant processing temperatures. These concepts are applied to silicon-containing steels that are currently being examined for low-carbon TRIP sheet steel applications, and medium-carbon bar steel applications, along with a silicon-containing ductile cast iron. Highlights of recent experimental studies on these materials are also presented, that indicate unique and attractive microstructure/property combinations may be obtained via Q&P. This work is being carried out through a collaborative arrangement sponsored by the NSF in the USA, CNPq in Brazil, and the EPSRC in the United Kingdom.

  12. Photoprotective capacity of non-photochemical quenching in plants acclimated to different light intensities.

    Science.gov (United States)

    Ware, Maxwell A; Belgio, Erica; Ruban, Alexander V

    2015-12-01

    Arabidopsis plants grown at low light were exposed to a gradually increasing actinic light routine. This method allows for the discerning of the photoprotective component of NPQ, pNPQ and photoinhibition. They exhibited lower values of Photosystem II (PSII) yield in comparison to high-light grown plants, and higher calculated dark fluorescence level (F'o calc.) than the measured one (F'o act.). As a result, in low-light grown plants, the values of qP measured in the dark appeared higher than 1. Normally, F'o act. and F'o calc. match well at moderate light intensities but F'o act. becomes higher at increasing intensities due to reaction centre (RCII) damage; this indicates the onset of photoinhibition. To explain the unusual increase of qP in the dark in low-light grown plants, we have undertaken an analysis of PSII antenna size using biochemical and spectroscopic approaches. Sucrose gradient separation of thylakoid membrane complexes and fast fluorescence induction experiments illustrated that the relative PSII cross section does not increase appreciably with the rise in PSII antenna size in the low-light grown plants. This suggests that part of the increased LHCII antenna is less efficiently coupled to the RCII. A model based upon the existence of an uncoupled population LHCII is proposed to explain the discrepancies in calculated and measured values of F'o.

  13. Molecular insights into Zeaxanthin-dependent quenching in higher plants

    Science.gov (United States)

    Xu, Pengqi; Tian, Lijin; Kloz, Miroslav; Croce, Roberta

    2015-01-01

    Photosynthetic organisms protect themselves from high-light stress by dissipating excess absorbed energy as heat in a process called non-photochemical quenching (NPQ). Zeaxanthin is essential for the full development of NPQ, but its role remains debated. The main discussion revolves around two points: where does zeaxanthin bind and does it quench? To answer these questions we have followed the zeaxanthin-dependent quenching from leaves to individual complexes, including supercomplexes. We show that small amounts of zeaxanthin are associated with the complexes, but in contrast to what is generally believed, zeaxanthin binding per se does not cause conformational changes in the complexes and does not induce quenching, not even at low pH. We show that in NPQ conditions zeaxanthin does not exchange for violaxanthin in the internal binding sites of the antennas but is located at the periphery of the complexes. These results together with the observation that the zeaxanthin-dependent quenching is active in isolated membranes, but not in functional supercomplexes, suggests that zeaxanthin is acting in between the complexes, helping to create/participating in a variety of quenching sites. This can explain why none of the antennas appears to be essential for NPQ and the multiple quenching mechanisms that have been observed in plants. PMID:26323786

  14. Numerical Methods for Safeguarding the Performance of the Quenching Process

    Institute of Scientific and Technical Information of China (English)

    I. FELDE; T. RETI; S. Segerberg; J. Bodin; G. S. Sarmiento; G. E. Totten; J. GU

    2004-01-01

    A new numerical technique for testing and evaluation of quenching media and quenching systems is outlined. The measured time-temperature samples as a result of cooling curve test are analyzed by the new software developed, in order to characterize quantitatively the quenchants. The method applied is based on Fourier analysis. Examples for evaluation and comparison of cooling performance of quenchants are presented the applicability of the computational technique.

  15. Design of Quenching Process for Large-sized AISI P20 Steel Block Used as Plastic Die

    Institute of Scientific and Technical Information of China (English)

    Dongli SONG; Jianfeng GU; Jiansheng PAN; Xin YAO

    2006-01-01

    For large-sized AISI P20 steel block used as plastic die with a thickness of more than 200 mm, appropriate quenching processes are the key to obtain much thick hardened layer. In this paper, different quenching processes of AISI P20 steel block such as oil quenching, direct water quenching, water quenching with precooling and water quenching with pre-cooling and self-tempering were numerically investigated by computer simulation based on the detailed discussion on the mathematical models of quenching processes including partial differential equations of heat transfer, thermal physical properties, latent heat, heat transfer coefficient and calculation of phase transformation, The results show that the water quenching with pre-cooling and self-tempering process can not only effectively avoid quenching cracks, but also obtain deeper harden depth than oil quenching.

  16. An optimised method for correcting quenched fluorescence yield

    Directory of Open Access Journals (Sweden)

    L. Biermann

    2014-05-01

    Full Text Available Under high light intensity, phytoplankton protect their photosystems from bleaching through non-photochemical quenching processes. The consequence of this is suppression of fluorescence emission, which must be corrected when measuring in situ yield with fluorometers. Previously, this has been done using the limit of the mixed layer, assuming that phytoplankton are uniformly mixed from the surface to this depth. However, the assumption of homogeneity is not robust in oceanic regimes that support deep chlorophyll maxima. To account for these features, we correct from the limit of the euphotic zone, defined as the depth at which light is at ~1% of the surface value. This method was applied to fluorescence data collected by eleven animal-borne fluorometers deployed in the Southern Ocean over four austral summers. Six tags returned data showing evidence of deep chlorophyll features. Using the depth of the euphotic layer, quenching was corrected without masking subsurface fluorescence signals.

  17. A layered cooling process in whole quenching process for lightweight front axle beam

    Directory of Open Access Journals (Sweden)

    Gao Kai

    2015-01-01

    Full Text Available In order to improve the uniformity of martensite distribution and obtain consistent mechanical performance during the quenching process of front axle beam, a layered cooling process was presented in this paper. The fluid-solid coupled temperature field were investigated by finite element modeling and the prediction of micro-structure and hardness distributions were also carried out. The experimental result verifies the reliability of this model.

  18. Effects of Quenching Process on Mechanical Properties and Microstructure of High Strength Steel

    Institute of Scientific and Technical Information of China (English)

    DUAN Zhengtao; LI Yanmei; ZHANG Mingya; SHI Minghan; ZHU Fuxian; ZHANG Shunhu

    2012-01-01

    The effects of direct quenching and tempering (DQ-T) process and conventional reheat quenching and tempering (RQ-T) processes on mechanical properties and microstructure of high strength steel were investigated.The DQ process was found to enhance the hardenability of steel effectively.The tensile strength and yield strength of DQ specimen was 975 MPa and 925 MPa respectively,which were higher than those of RQ specimen's of 920 MPa and 871 MPa.In contrast,low temperature toughness (-40 ℃,AKV) of DQ-T specimen (124 J) was generally inferior to that of RQ-T specimen (156 J).The direct quenching temperature was one of the potential process parameters to determine strength/toughness balance of steel manufactured by DQ process.The experimental results showed that excellent strength/toughness balance was obtained when the specimens was quenched at temperature in the range of 850-910 ℃.The yield strength and impact energy (-40 ℃) of DQ steel decreased significantly with increasing of quenching temperature,although the tensile strength was nearly stable.

  19. Analyses of quenching process during turn-off of plasma electrolytic carburizing on carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jie; Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Wang, Bin; Jin, Xiaoyue; Du, Jiancheng [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-10-15

    Highlights: • Cooling rate of carburized steel at the end of PEC treatment is measured. • The quench hardening in the fast or slow turn-off mode hardly takes place. • Decrease of the surface roughness during slow turn-off process is found. • A slow turn-off mode is recommended to replace the conventional turn-off mode. - Abstract: Plasma electrolytic carburizing (PEC) under different turn-off modes was employed to fabricate a hardening layer on carbon steel in glycerol solution without stirring at 380 V for 3 min. The quenching process in fast turn-off mode or slow turn-off mode of power supply was discussed. The temperature in the interior of steel and electron temperature in plasma discharge envelope during the quenching process were evaluated. It was found that the cooling rates of PEC samples in both turn-off modes were below 20 °C/s, because the vapor film boiling around the steel sample reduced the cooling rate greatly in terms of Leidenfrost effect. Thus the quench hardening hardly took place, though the slow turn-off mode slightly decreased the surface roughness of PEC steel. At the end of PEC treatment, the fast turn-off mode used widely at present cannot enhance the surface hardness by quench hardening, and the slow turn-off mode was recommended in order to protect the electronic devices against a large current surge.

  20. Polyamines induce aggregation of LHC II and quenching of fluorescence in vitro.

    Science.gov (United States)

    Tsiavos, Theodoros; Ioannidis, Nikolaos E; Kotzabasis, Kiriakos

    2012-05-01

    Dissipation of excess excitation energy within the light-harvesting complex of Photosystem II (LHC II) is a main process in plants, which is measured as the non-photochemical quenching of chlorophyll fluorescence or qE. We showed in previous works that polyamines stimulate qE in higher plants in vivo and in eukaryotic algae in vitro. In the present contribution we have tested whether polyamines can stimulate quenching in trimeric LHC II and monomeric light-harvesting complex b proteins from higher plants. The tetramine spermine was the most potent quencher and induced aggregation of LHC II trimers, due to its highly cationic character. Two transients are evident at 100 μM and 350 μM for the fluorescence and absorbance signals of LHC II respectively. On the basis of observations within this work, some links between polyamines and the activation of qE in vivo is discussed.

  1. Modelling of the carburizing and quenching process applied to caterpillar track bushings

    Science.gov (United States)

    Ferro, P.; Bonollo, F.

    2014-03-01

    The carburizing-quenching process applied to caterpillar track bushings was studied by means of experimental and numerical analyses. The numerical model was developed on the basis of the real cycle. The purpose of this work is to predict the carbon profiles, microstructural phase changes, hardness and residual stress that occur during quenching using finite element techniques. Good agreement was obtained between the experimental and numerical results in terms of carbon diffusion and hardness profiles. The Sysweld® numerical code was used to perform the simulations.

  2. Overview of mechanisms involved during the quenching and partitioning process in steels

    NARCIS (Netherlands)

    Santofimia, M.J.; Zhao, L.; Sietsma, J.

    2011-01-01

    The application of the quenching and partitioning (Q&P) process in steels involves a microstructural evolution that is more complex than just the formation of martensite followed by carbon partitioning from martensite to austenite. Examples of this complexity are the formation of epitaxial ferrite

  3. Modelling of quenching process of medium-carbon steel

    Directory of Open Access Journals (Sweden)

    A. Kulawik

    2010-01-01

    Full Text Available The paper refers to numerical modelling of the hardening process of steel C45. In the algorithm the heat transfer equation, equilibrium equations and macroscopic model of phase transformations, basis of CCT diagrams, are used. Coupling between basic phenomena of hardening process is considered, in particular the influence of latent heat on the fields of temperature, and also thermal, structural and plastic strains and transformation - induced plasticity in the model is taken into account as well. The method of calculating the phase transformation during heating applied by the authors uses data from the continuous heating diagram (CHT. The homogenization line of austenite determines the end of heating. The influence of austenisation temperature on the kinetics of transformations is taken into account. To calculate the increase of martensite content Koistinen-Marburger formula is used. Field of stresses and strains are obtained from solutions of finite element method equations of equilibrium in increment form.

  4. Titanium Metal Powder Production by the Plasma Quench Process

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Cordes; A. Donaldson

    2000-09-01

    The goals of this project included the scale-up of the titanium hydride production process to a production rate of 50 kg/hr at a purity level of 99+%. This goal was to be achieved by incrementally increasing the production capability of a series of reactor systems. This methodic approach was designed to allow Idaho Titanium Technologies to systematically address the engineering issues associated with plasma system performance, and powder collection system design and performance. With quality powder available, actual fabrication with the titanium hydride was to be pursued. Finally, with a successful titanium production system in place, the production of titanium aluminide was to be pursued by the simultaneously injection of titanium and aluminum precursors into the reactor system. Some significant accomplishments of the project are: A unique and revolutionary torch/reactor capable of withstanding temperatures up to 5000 C with high thermal efficiency has been operated. The dissociation of titanium tetrachloride into titanium powder and HC1 has been demonstrated, and a one-megawatt reactor potentially capable of producing 100 pounds per hour has been built, but not yet operated at the powder level. The removal of residual subchlorides and adsorbed HC1 and the sintering of powder to form solid bodies have been demonstrated. The production system has been operated at production rates up to 40 pounds per hour. Subsequent to the end of the project, Idaho Titanium Technologies demonstrated that titanium hydride powder can indeed be sintered into solid titanium metal at 1500 C without sintering aids.

  5. Analyses of quenching process during turn-off of plasma electrolytic carburizing on carbon steel

    Science.gov (United States)

    Wu, Jie; Liu, Run; Xue, Wenbin; Wang, Bin; Jin, Xiaoyue; Du, Jiancheng

    2014-10-01

    Plasma electrolytic carburizing (PEC) under different turn-off modes was employed to fabricate a hardening layer on carbon steel in glycerol solution without stirring at 380 V for 3 min. The quenching process in fast turn-off mode or slow turn-off mode of power supply was discussed. The temperature in the interior of steel and electron temperature in plasma discharge envelope during the quenching process were evaluated. It was found that the cooling rates of PEC samples in both turn-off modes were below 20 °C/s, because the vapor film boiling around the steel sample reduced the cooling rate greatly in terms of Leidenfrost effect. Thus the quench hardening hardly took place, though the slow turn-off mode slightly decreased the surface roughness of PEC steel. At the end of PEC treatment, the fast turn-off mode used widely at present cannot enhance the surface hardness by quench hardening, and the slow turn-off mode was recommended in order to protect the electronic devices against a large current surge.

  6. Experimental Study of Quenching Process During Bottom Reflooding Using “Queen” Test Section

    Directory of Open Access Journals (Sweden)

    M. Juarsa

    2005-01-01

    Full Text Available Phenomenon of quenching of hot fuels in core during bottom reflooding following loca event is investigated in order to understand the performance cooling process. the study is conducted experimentally using queen test section which allow study of rod surface temperature histories based on which the heat fluxes are estimated. the visual observation is also done to study the boiling regimes. the test variables are initial rod temperature, i.e. 400oc, 500oc and 600oc, and coolant flow rate, i.e. 0,01kg/s, 0.02 kg/s and 0.04 kg/s with constant water inlet temperature of 30oc. the results shows different heat transfer regimes such as film boiling, transition boiling, nucleate boiling and convective single phase heat transfer regimes. for specified initial rod temperature, the higher flow rate provides high rewet velocity and higher maximum heat flux, then quenching process is more effective.

  7. Surface properties of low alloy steel treated by plasma nitrocarburizing prior to laser quenching process

    Science.gov (United States)

    Wang, Y. X.; Yan, M. F.; Li, B.; Guo, L. X.; Zhang, C. S.; Zhang, Y. X.; Bai, B.; Chen, L.; Long, Z.; Li, R. W.

    2015-04-01

    Laser quenching (LQ) technique is used as a part of duplex treatments to improve the thickness and hardness of the surface layers of steels. The present study is to investigate the surface properties of low alloy steel treated by plasma nitrocarburizing (PNC) prior to a laser quenching process (PNC+LQ). The microstructure and properties of PNC+LQ layer determined are compared with those obtained by PNC and LQ processes. OM, XRD, SEM and EDS analyses are utilized for microstructure observation, phases identification, morphology observation and chemical composition detection, respectively. Microhardness tester and pin-on-disc tribometer are used to investigate the mechanical properties of the modified layers. Laser quenching of plasma nitrocarburized (PNC+LQ) steel results in much improved thickness and hardness of the modified layer in comparison with the PNC or LQ treated specimens. The mechanism is that the introduction of trace of nitrogen decreases the eutectoid point, that is, the transformation hardened region is enlarged under the same temperature distribution. Moreover, the layer treated by PNC+LQ process exhibits enhanced wear resistance, due to the lubrication effect and optimized impact toughness, which is contributed to the formation of oxide film consisting of low nitrogen compound (FeN0.076) and iron oxidation (mainly of Fe3O4).

  8. Numerical calculation of temperature and phase change during the process of atomizing spray quenching on drilling pipe

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A finite element method (FEM) procedure was developed in order to simulate the quenching process for drilling pipe (DP).The calculating model was based on time-temperature-transformation (TTT) diagrams, and incorporated with material properties de-pendent on temperature. The procedure was used to calculate the temperature-time histories, describe the phase transformations ofatomizing spray quenching for DP in the welding zone, and predict the hardness distribution in radius direction after quenching in thezone. The calculated results met well with that of experiments. It was easy to determine the parameters such as volume and pressureof the cooling water and compressed gas by use of the numerical calculation and experiments, because the value of convection coef-ficient was decided greatly by the mixture of the cooling water and compressed gas. Moreover, the simulating results were helpfulnot only to design the quenching equipment, but also to optimize the quenching process for DP's welding zone.

  9. Interface Migration between Martensite and Austenite during Quenching and Partitioning (Q&P) Process

    Institute of Scientific and Technical Information of China (English)

    Ning ZHONG; Xiaodong WANG; Yonghua RONG; Li WANG

    2006-01-01

    An Fe-0.2C-1.5Si-1.67Mn steel was subjected to quenching and partitioning (Q&P) process, and the interface migration between martensite and austenite at an elevated partitioning temperature was observed. The interface migration is excluded in constrained paraequilibrium (CPE) model. Based on "endpoint" predicted by CPE model the thermodynamic condition of interface migration is analyzed, that is, the difference in the chemical potential of iron in both ferrite (martenisite) and austenite produces the driving force of the iron atoms to migrate from one phase to the other phase. In addition, the interface migration can change the austenite fraction; as a result, the austenite fraction at partitioning temperature may be higher than that at quenching temperature through the interface migration, but this phenomenon cannot be explained by CPE model.

  10. Hydrophobic Acceleration of Electron-Transfer Fluorescence Quenching Processes between Excited 1-Alkanoylperylenes and Ferrocene Derivatives

    Institute of Scientific and Technical Information of China (English)

    SHI, Ji-Liang

    2001-01-01

    Coaggregation-facilitated Electron-transfer (ET) fluorescence quenching processes between an excited 1-alkanoylperylene (Pe-n, n=4, 8, 12) as an acceptor and an 1-alkanoylferrocene (Fc-m, m=4, 8, 12, 16 ) or a 1,1-dialkanoyiferrocene (Fc-m-2, m=4, 8, 12, 16) as a donor have been investigated by means of fluorescence spectroscopy in dioxane (DX)H2O binary solvents of different φ values, where φ is the volume fraction of the organic component of an aquiorgano mixture. This is a first observation of an ET processes facilitated by hydrophobic-lipophilic interaction (HLI) with organometallic compounds as donors. Tne extent of HLI-driven coaggregation between the acceptor and the donor may be assessed from the efficiency of fluorescence quenching, i.e.,the slope B of Eq. ( 2 ). The chain-foldability effect and the intramolecular “self-satisfation” of HLI for Fc-m-2 have been observed. The experimental results show that the behavior of Fc-m as a quencher for fluorescence quenching of Pen* is rather similar to that of N-alkylsubstituend phenothiazine.

  11. Identification of the chromophores involved in aggregation-dependent energy quenching of the monomeric photosystem II antenna protein Lhcb5.

    Science.gov (United States)

    Ballottari, Matteo; Girardon, Julien; Betterle, Nico; Morosinotto, Tomas; Bassi, Roberto

    2010-09-03

    Non-photochemical quenching (NPQ) of excess absorbed light energy is a fundamental process that regulates photosynthetic light harvesting in higher plants. Among several proposed NPQ mechanisms, aggregation-dependent quenching (ADQ) and charge transfer quenching have received the most attention. In vitro spectroscopic features of both mechanisms correlate with very similar signals detected in more intact systems and in vivo, where full NPQ can be observed. A major difference between the models is the proposed quenching site, which is predominantly the major trimeric light-harvesting complex II in ADQ and exclusively monomeric Lhcb proteins in charge transfer quenching. Here, we studied ADQ in both monomeric and trimeric Lhcb proteins, investigating the activities of each antenna subunit and their dependence on zeaxanthin, a major modulator of NPQ in vivo. We found that monomeric Lhcb proteins undergo stronger quenching than light-harvesting complex II during aggregation and that this is enhanced by binding to zeaxanthin, as occurs during NPQ in vivo. Finally, the analysis of Lhcb5 mutants showed that chlorophyll 612 and 613, in close contact with lutein bound at site L1, are important facilitators of ADQ.

  12. Anaerobiosis induced state transition: a non photochemical reduction of PQ pool mediated by NDH in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Sreedhar Nellaepalli

    Full Text Available BACKGROUND: Non photochemical reduction of PQ pool and mobilization of LHCII between PSII and PSI are found to be linked under abiotic stress conditions. The interaction of non photochemical reduction of PQ pool and state transitions associated physiological changes are critically important under anaerobic condition in higher plants. METHODOLOGY/FINDINGS: The present study focused on the effect of anaerobiosis on non-photochemical reduction of PQ pool which trigger state II transition in Arabidopsis thaliana. Upon exposure to dark-anaerobic condition the shape of the OJIP transient rise is completely altered where as in aerobic treated leaves the rise is unaltered. Rise in F(o and F(J was due to the loss of oxidized PQ pool as the PQ pool becomes more reduced. The increase in F(o' was due to the non photochemical reduction of PQ pool which activated STN7 kinase and induced LHCII phosphorylation under anaerobic condition. Further, it was observed that the phosphorylated LHCII is migrated and associated with PSI supercomplex increasing its absorption cross-section. Furthermore, evidences from crr2-2 (NDH mutant and pgr5 mutants (deficient in non NDH pathway of cyclic electron transport have indicated that NDH is responsible for non photochemical reduction of the PQ pool. We propose that dark anaerobic condition accelerates production of reducing equivalents (such as NADPH by various metabolic pathways which reduce PQ pool and is mediated by NDH leading to state II transition. CONCLUSIONS/SIGNIFICANCE: Anaerobic condition triggers non photochemical reduction of PQ pool mediated by NDH complex. The reduced PQ pool activates STN7 kinase leading to state II transition in A. thaliana.

  13. Computer Simulation on Metallic Card Clothing Garnett Wire Teeth's Temperature Field & Structure Field in the Process of Quenching Treatment

    Institute of Scientific and Technical Information of China (English)

    WU Liang; REN Shi-he

    2006-01-01

    The quenching process of garnett wire teeth of metallic card clothing heated by flame was researched by use of 3-D finite element method and the equation of boundary condition was established by making use of a model of artificial neural network. The transient temperature field, phase transformation in the heating process, the quenching microstructures and the hardness distribution on quenched garnett wire teeth of metallic card clothing were simulated.The result shows that the maximum error of the hardness between the simulative value and the actual measuring value is 8.0% on only one testing point and errors are all less than 3.0% on other testing points.

  14. Fast quenching processes and their impact on 1.5-µm amplifier performance in $Al_2O_3:Er^{3+}$ waveguides

    NARCIS (Netherlands)

    Agazzi, L.; Wörhoff, K.; Pollnau, M.

    2012-01-01

    Spectroscopic investigations reveal the presence of a fast quenching process in erbium-doped aluminum oxide waveguides. We quantify the percentage of quenched ions and make predictions about the amplifier performance.

  15. Efficiency droop in indium gallium nitride light emitters: An introduction to photon quenching processes

    Science.gov (United States)

    Sarkissian, Raymond

    This thesis contains work from two separate projects, a study of the efficiency of light emitting diodes, and a tapered-fiber approach to photonic crystal integrated photonics. The first part of this thesis describes an experimental investigation of the quantum efficiency of InGaN-based light emitters. Blue and Green LEDs that utilize InGaN quantum wells for their active medium suffer from a reduction in efficiency with increasing bias. This phenomenon is called efficiency droop. In this thesis experimental evidence for significant quenching of photon population in InGaN is presented and its relevance to the efficiency droop problem in InGaN-based light emitting structures is discussed. An equilibrium rate equation model is set up to demonstrate that radiative efficiency for this loss mechanism not only has a similar dependence on carrier density as Auger recombination process, but it also possesses the right order of magnitude making it difficult to distinguish between the two and possibly leading to errors in interpretation. The impact of photon quenching processes on device performance is emphasized by demonstrating loss of efficiency for spectral regions where there is experimental evidence for photon quenching. We have observed this phenomenon for both c-plane and m-plane light emitting structures. Both structures exhibit droop-like behavior for spectral regions where there is evidence for photon quenching. We have also observed and characterized the dynamical Stark effect for an m-plane light emitter considered in this manuscript. Our results revealed localization centers with a corresponding band-edge energy of 388nm and an excitonic binding energy of 17.81mev. Furthermore, fabrication of a photonic crystal waveguide fiber taper coupler is demonstrated with a peak coupling efficiency of 97 %. All four ports of the device are accessible providing an opportunity for investigation of simultaneous interaction of different light sources inside the photonic

  16. Is the Electron Avalanche Process in a Martian Dust Devil Self-Quenching?

    Science.gov (United States)

    Farrell, William M.; McLain, Jason L.; Collier, M. R.; Keller, J. W.; Jackson, T. J.; Delory, G. T.

    2015-01-01

    Viking era laboratory experiments show that mixing tribocharged grains in a low pressure CO2 gas can form a discharge that glows, indicating the presence of an excited electron population that persists over many seconds. Based on these early experiments, it has been predicted that martian dust devils and storms may also contain a plasma and new plasma chemical species as a result of dust grain tribo-charging. However, recent results from modeling suggest a contrasting result: that a sustained electron discharge may not be easily established since the increase in gas conductivity would act to short-out the local E-fields and quickly dissipate the charged grains driving the process. In essence, the system was thought to be self-quenching (i.e., turn itself off). In this work, we attempt to reconcile the difference between observation and model via new laboratory measurements. We conclude that in a Mars-like low pressure CO2 atmosphere and expected E-fields, the electron current remains (for the most part) below the expected driving tribo-electric dust currents (approx. 10 microA/m(exp. 2)), thereby making quenching unlikely.

  17. Effects of habitat light conditions on the excitation quenching pathways in desiccating Haberlea rhodopensis leaves: an Intelligent FluoroSensor study.

    Science.gov (United States)

    Solti, Ádám; Lenk, Sándor; Mihailova, Gergana; Mayer, Péter; Barócsi, Attila; Georgieva, Katya

    2014-01-05

    Resurrection plants can survive dehydration to air-dry state, thus they are excellent models of understanding drought and dehydration tolerance mechanisms. Haberlea rhodopensis, a chlorophyll-retaining resurrection plant, can survive desiccation to relative water content below 10%. Leaves, detached from plants of sun and shade habitats, were moderately (∼50%) dehydrated in darkness. During desiccation, chlorophyll a fluorescence was detected by the recently innovated wireless Intelligent FluoroSensor (IFS) chlorophyll fluorometer, working with three different detectors: a pulse-amplitude-modulated (PAM) broadband channel and two channels to measure non-modulated red and far-red fluorescence. No change in area-based chlorophyll content of leaves was observed. The maximal quantum efficiency of photosystem II decreased gradually in both shade and sun leaves. Shade leaves could not increase antennae-based quenching, thus inactivated photosystem II took part in quenching of excess irradiation. Sun leaves seemed to be pre-adapted to quench excess light as they established an intensive increase in antennae-based non-photochemical quenching parallel to desiccation. The higher far-red to red antennae-based quenching may sign light-harvesting complex reorganization. Thus, compared to PAM, IFS chlorophyll fluorometer has additional benefits including (i) parallel estimation of changes in the Chl content and (ii) prediction of underlying processes of excitation energy quenching.

  18. High pressure effect on structural transition of Fe cluster during rapid quenching processes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Molecular dynamics simulations of 21,952 atoms have been performed to study local structure evolution and glass formation in iron melts rapidly cooled under high pressures.In the quenching processes,structural transition details have been analyzed by using the radial distribution function g(r) and bond pair analysis technique.It is shown that high pressure strengthens the order degree of the glass system and favors the glass formation.That means with the increase of pressures,a more compacted local structure with more ideal icosahedra can be obtained.The calculations of free volume of the system indicate that the decrease of the number of the defected ideal icosahedra under high pressure contributes to the glass formation of Fe.

  19. On structure-property relationship in nanostructured bainitic steel subjected to the quenching and partitioning process

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Ping [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Gao, Guhui, E-mail: gaogh@bjtu.edu.cn [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Han [Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Tan, Zhunli [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Misra, R.DK. [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, TX 79968-0520 (United States); Bai, Bingzhe [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Tsinghua University, Key Laboratory of Advanced Material, School of Material Science and Engineering, Beijing 100084 (China)

    2016-04-20

    We elucidate here the mechanistic contribution of the application of quenching and partitioning (Q&P) concept to a high carbon Mn-Si-Cr steel in obtaining a multiphase microstructure comprising of martensite/austenite and nanostructured bainite (bainitic ferrite and nanometer-sized film-like retained austenite) that exhibited tensile strength of 1923 MPa and total elongation of 18.3%. The excellent mechanical properties are attributed to the enhanced refinement of blocky austenite islands obtained by the Q&P process. The austenite was stabilized by both carbon partitioning from martensite and bainite transformation. Compared with conventional heat treatment to produce nanostructured bainite, the total time is significantly reduced without degradation of mechanical properties.

  20. Computer Simulation of the Process of Quenching Large-Size Parts in Water and Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    N.I.Kobasko; W.S.Morhuniuk; V.V.Dobrivecher; A.M.Weinov

    2004-01-01

    The article presents results of the computer simulation of quenching large-size parts in water and aqueous solutions. It has been shown that the main attention should be paid to eliminating film boiling and providing uniform cooling at the surface of the part to be quenched. Simplified formulas for calculating the optimal time of cooling large-size steel parts are presented.

  1. Analyzing the influence of contact-induced quenching processes on Förster resonance energy transfer

    Science.gov (United States)

    Brune, Ralf; Doose, Sören; Sauer, Markus

    2007-07-01

    Experiments based on Förster resonance energy transfer (FRET) are widely used to obtain information on conformational dynamics of biomolecular systems. To reliably measure FRET, accurate knowledge of photophysical properties of the used fluorophores is indispensable. In high FRET constructs donor (D) and acceptor (A) fluorophores can approach each other close enough that electronic interactions might occur. When separated by distances on the order of van der Waals radii, photophysical properties can be changed reversibly, opening new non-radiative relaxation pathways, or irreversibly, chemically altering the fluorophores. Even transient contacts can thus compromise accurate FRET measurements. To study FRET and competing D-A contact-induced processes we labeled the amino acid cystein (Cys) with two fluorophores. A donor (D; TMR or Cy3B) was attached to the thiol group and an acceptor (A; Atto647N) to the amino group of Cys. Absorption spectroscopy, steady-state fluorescence spectroscopy, and time-correlated single-photon counting (TCSPC) were used to characterize the different A-Cys-D complexes at the ensemble level. In addition, we performed single-molecule FRET experiments using alternating-laser excitation to study the heterogeneity of the FRET-systems. We identified competing quenching processes severely changing D and A quantum yields upon fluorophore contact. The results are applicable for quantitative analysis of FRET in dynamic molecular systems that allow transient contact between D and A fluorophores.

  2. Influence of Parameters of Quenching and Partitioning Process on Microstructure and Fraction of Retained Austenite

    Directory of Open Access Journals (Sweden)

    A. Shirali

    2015-07-01

    of partitioning temperature made the retained austenite films become thicker and its volume fraction increase. On the other hand, by increasing the quenching temperature, carbon content of retained austenite increased sharply.

  3. Formation Processes of Nanocomposite Strengthening Particles in Rapidly Quenched Al-Sc-Zr Alloys

    Directory of Open Access Journals (Sweden)

    A.V. Kotko

    2012-03-01

    Full Text Available Decomposition processes of supersaturated solid solution of aluminium alloys alloyed with Sc and Zr have been studied in the work. The binary hypereutectic Al-Sc alloys, hyperperitectic Al-Zr alloys and ternary Al-Sc-Zr alloys were chosen. Alloys were obtained by the melt-spinning. Melts were quenched from temperatures of Т = 1000 C and Т = 1400 ºC. The study of the structure of rapidly solidifyed binary Al alloys alloyed with Sc and Zr showed that the crystallization of anomalously supersaturated solid solution (Tquen. = 1400 ºC or the crystallization with the formation of "fan" structure (Tquen. = 1000 ºC are possible depending on the quenching temperature of the melt. The decomposition of anomalously supersaturated solid solution is continuous, with the precipitation of nano-sized spherical Al3X (X-Sc, Zr particles of L12-ordered phase which is isomorphous to matrix. It was found that the loss of thermal stability of Al-Sc alloys is due to the loss of coherence of the strengthening Al3Sc phase. In Al-Zr alloys the loss of strength is due to the formation of a stable tetragonal DO23-ordered A13Zr phase. After co-alloying of Al by Sc and Zr a bimodal grained structure was observed for the hypereutectic ternary alloy (Tquen. = 400ºC. Nano-sized grains of 50-60 nm were present on the boundaries of 1-2 µm large-sized grains. TEM shows the formation of nanocomposite Al3Zr/Al3Sc particles. The formation of Al3Zr shell changes the nature of the interfacial fit of the particle with the matrix and slows down the decomposition during the coalescence. Ternary Al-Sc-Zr alloys have significantly higher thermal stability during aging as compared to binary Al-Sc and Al-Zr alloys. Decomposition processes of supersaturated solid solution of aluminium alloys alloyed with Sc and Zr have been studied in the work. The binary hypereutectic Al-Sc alloys, hyperperitectic Al-Zr alloys and ternary Al-Sc-Zr alloys were chosen. Alloys were

  4. Integrated Al2O3:Er3+ amplifiers: The impact of fast spectroscopic quenching processes

    NARCIS (Netherlands)

    Agazzi, L.; Bradley, J.D.B.; Wörhoff, K.; Pollnau, M.

    2011-01-01

    We report a number of recently demonstrated integrated Al2O3:Er3+ devices and present spectroscopic investigations revealing the presence of a fast quenching mechanism – undetected in typical luminescence decay measurements – which limits the Al2O3:Er3+ amplifier performance.

  5. Phase-Separation Control of KxFe2-ySe2 Superconductor through Rapid-Quenching Process

    Science.gov (United States)

    Yanagisawa, Yusuke; Tanaka, Masashi; Yamashita, Aichi; Suzuki, Kouji; Hara, Hiroshi; ElMassalami, Mohammed; Takeya, Hiroyuki; Takano, Yoshihiko

    2017-04-01

    KxFe2-ySe2 exhibits iron-vacancy ordering at Ts ˜ 270 °C and separates into two phases: a minor superconducting (iron-vacancy-disordered) phase and a major non-superconducting (iron-vacancy-ordered) phase. The microstructural and superconducting properties of this intermixture can be tuned by an appropriate control of the quenching process through Ts. A faster quenching rate leads to a finer microstructure and a suppression of formation of the non-superconducting phase by up to 50%. Nevertheless, such a faster cooling rate induces a monotonic reduction in the superconducting transition temperature (from 30.7 to 26.0 K) and, simultaneously, a decrease in the iron content within the superconducting phase such that the compositional ratio changed from K0.35Fe1.83Se2 to K0.58Fe1.71Se2.

  6. Modeling of numerical simulation and experimental verification for carburizing-nitriding quenching process

    Institute of Scientific and Technical Information of China (English)

    R. MUKAI; T. MATSUMOTO; JU Dong-ying; T. SUZUKI; H. SAITO; Y. ITO

    2006-01-01

    A model considering quantitative effects of diffused carbon and nitrogen gradients and kinetics of phase transformation is presented to examine metallo-thermo-mechanical behavior during carburized and nitrided quenching. Coupled simulation of diffusion,phase transformation and stress/strain provides the final distribution of carbon and nitrogen contents as well as residual stress and distortion. Effects of both transformation and lattice expansion induced by carbon and nitrogen absorption were introduced into calculating the evolution of the internal stress and strain. In order to verify the method and the results,the simulated distributions of carbon and nitrogen content and residual stress/strain of a ring model during carburized and nitrided quenching were compared with the measured data.

  7. 提高丙烯腈回收率的一种新型急冷工艺和急冷塔%A new quenching process and tower to improve the recovery of acrylonitrile

    Institute of Scientific and Technical Information of China (English)

    甘永胜; 顾军民; 方永成

    2004-01-01

    Quenching process and design of the quenching tower in acrylonitrile production in China were studied in order to decrease the polymerization loss of acrylonitrile in the quenching tower.Based on the research of acrylonitrile polymerization in the quenching tower,a new quenching process was proposed to avoid the disadvantages of the original process.Two kinds of internals were installed to improve the performance of the quenching tower.Through a series of air-flow and real-flow model experiments,the new quenching process and new design were showed to be successful in enhancing the mass and heat transfer in the vapor-liquid system and decreasing the loss of acrylonitrile.Industrial application showed satisfactory results of decrease of the acrylonitrile loss in the quenching tower by about 4.5% and increase of the acrylonitrile recovery of the whole plant by more than 4%.

  8. Process for removing harmful material after wet quenching in coke oven quenching towers with simultaneous water treatment. Verfahren zur Schadstoffbeseitigung hinter der Nassloeschung in Kokerei-Loeschtuermen bei gleichzeitiger Wasseraufbereitung

    Energy Technology Data Exchange (ETDEWEB)

    Hoelter, H.; Igelbuescher, H.; Gresch, H.; Dewert, H.

    1987-05-27

    In the main patent application P 3538138.8, a process for removing emission from a coke quenching tower is described, where the quenching hood is situated behind the actual quenching tower and the quantities of gas are sprayed with liquids washing out the SO/sub 2/ via condensor arrangements with heat exchangers, where the amounts of gas are restricted to a minimum by condensation and the quantity of gas in clouds of gas is then taken to a dust extractor. In order to improve the process of the main application further, this invention proposes that a dry chemi-sorption technique should be applied after the quenching tower, which is equipped with masses absorbing chemicals and simultaneously absorbing humidity. The chemi-sorption masses taken to the chemi-sorption filter consist of a core material, which is reinforced with means of absorption binding acids to absorb gaseous harmful substances like SO/sub 2/ H/sub 2/S, CN and which also causes the conversion of substances loaded with NO/sub x/.

  9. A Cooperative Activity on Quenching Process Simulation--- Japanese IMS-VHT Project on the Benchmark Analysis and Experiment ---

    Institute of Scientific and Technical Information of China (English)

    Tatsuo Inoue; Youichi Watanabe; Kazuo Okamura; Michiharu Narazaki; Hayato Shichino; Dong-Ying Ju; Hideo Kanamori; Katsumi Ichitani

    2004-01-01

    Japanese IMS-VHT project on the Virtual Heat Treatment tool for monitoring and optimising HT process in relation with the international cooperative programs is briefly introduced. This project motivates to develop virtual tools for computer to optimize the heat treatment condition and to support decision for HT operation by knowledge based database in addition to process simulation. As one of the activities with the cooperation of the Society of Materials Science, Japan and the Japan Society for Heat Treatment, a benchmark project is undergoing. This includes simulation of carburized quenching process of a cylinder, disc, and ring as well as a helical gear by use of common data of materials properties and cooling characteristics by several available simulation programs. A part of the newly obtained results is presented as an interim report.

  10. Comparison on mechanical properties and microstructure of a C–Mn–Si steel treated by quenching and partitioning (Q and P) and quenching and tempering (Q and T) processes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shu [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Liu, Xianghua, E-mail: liuxh@mail.neu.edu.cn [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Research Academy, Northeastern University (China); Liu, Wayne J. [Research Academy, Northeastern University (China); Lan, Huifang; Wu, Hongyan [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China)

    2015-01-03

    A steel containing Fe–0.20C–1.57Mn–1.55Si–0.0029P–0.0018S (wt%) was treated by quenching and partitioning (Q and P) and quenching and tempering (Q and T) process. The resulted mechanical properties indicate that the Q and P process may bring on an excellent combination of strength and elongation for the steel, of which the product was between 14.5 and 20.4 GPa%. The morphological relationship between the retained austenite and martensite was characterized as well. It was found that the TRIP effect of retained austenite plays an important role in enhancing the work hardening rate and instantaneous n-value at high strain level, which further increases the uniform elongation. Fractography of samples treated by Q and P process showed mainly ductile mechanism, while a small percentage of brittle fracture exists in the samples treated by Q and T process. Possible isothermal decomposition of austenite at quenching temperature (QT) and partitioning temperature (PT) and its effect on carbon partitioning was discussed.

  11. Light harvesting and Blue-Green light induced non-photochemical quenching in two different C-phycocyanin mutants of synechocytis PCC 6803

    NARCIS (Netherlands)

    Tian, L.; Stokkum, van I.H.M.; Koehorst, R.B.M.; Amerongen, van H.

    2013-01-01

    Cyanobacteria are oxygen-evolving photosynthetic organisms that harvest sunlight and convert excitation energy into chemical energy. Most of the light is absorbed by large light harvesting complexes called phycobilisomes (PBs). In high-light conditions, cyanobacteria switch on a photoprotective mech

  12. Effect of Welding Processes and Consumables on Tensile and Impact Properties of High Strength Quenched and Tempered Steel Joints

    Institute of Scientific and Technical Information of China (English)

    G Magudeeswaran; V Balasubramanian; G Madhusudhan Reddy; T S Balasubramanian

    2008-01-01

    Quenched and tempered steels are prone to hydrogen induced cracking in the heat affected gone after welding.The use of austenitic stainless steel consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase.In this investigation,an attempt was made to determine a suitable consumable to replace expensive austenitic consumables.Two different consumables,namely,austenitic stainless steel and lOW hydrogen ferritic steel,were used to fabricate the joints by shielded metal arc welding(SMAW)and flux cored arc welding(FCAW)processes.The joints fabricated by using low hydrogen ferritic steel consumables showed superior transverse tensile properties,whereas joints fabricated by using austenitic stainless steel consumables exhibited better impact toughness,irrespective of the welding process used.The SMAW joints exhibited superior mechanical and impact properties,irrespective of the consumables used,than their FCAW counterparts.

  13. Research on Parts Process of V-shape Slot Carburizing Quenching%V型槽渗碳淬火零件加工工艺研究

    Institute of Scientific and Technical Information of China (English)

    陈惠娟; 黄玉方; 梁壮; 王健

    2012-01-01

    通过对V型槽渗碳淬火类零件的特性及加工难点的分析,研究V型槽渗碳淬火类零件的工艺总方案及加工工艺.主要针对2种不同结构类型的V型槽渗碳淬火类零件的加工工艺及加工过程进行分析,探讨V型槽渗碳淬火零件的特殊加工方法.通过对V型槽渗碳淬火类零件的生产加工和加工过程中的工艺改进与完善,摸索到了加工V型槽渗碳淬火零件的一些经验,供大家参考.%By analyzing the characteristics of V-shape slot carburizing quenching parts and the difficulties of processing, the paper mainly focused on the general plan and processing technology of the V-shape slot carburizing quenching parts. By analyzing parts processing technology and processing procedure of two different structures of the V-shape slot carburizing quenching, the paper discussed the specific processing method of the V-shape slot carburizing quenching parts. By making improvements and perfection of the production processing and the process technology of the V-shape slot carburizing quenching parts, we have got some experiences from the processing of the V-shape slot carburizing quenching parts for your reference.

  14. Proposed Quenching of Phonon-Induced Processes in Photoexcited Quantum Dots due to Electron-Hole Asymmetries

    DEFF Research Database (Denmark)

    Nysteen, Anders; Nielsen, Per Kær; Mørk, Jesper

    2013-01-01

    by photoluminescence excitation spectroscopy of a single quantum dot. We also investigate the implications for cavity QED, i.e., a coupled quantum dot-cavity system, and demonstrate that the phonon scattering may be strongly quenched. The quenching is explained by a balancing between the deformation potential...

  15. Experimental and Numerical Studies on the Formability of Materials in Hot Stamping and Cold Die Quenching Processes

    Science.gov (United States)

    Li, N.; Mohamed, M. S.; Cai, J.; Lin, J.; Balint, D.; Dean, T. A.

    2011-05-01

    Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic-damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. The determined unified constitutive equations are then implemented into the commercial Finite Element code Abaqus/Explicit via a user defined subroutine, VUMAT. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole. Different failure modes (failure takes place either near the central hole or in the mid span of the part) are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates. It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out.

  16. Simulation of quenching-tempering process based on metallo-thermo-mechanics; Hentai-netsu-rikigaku ni motozuku yakiire/yakimodoshi katei no simulation to sono kensho

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Dongying [Saitama Univ., Saitama (Japan). Faculty of Engineering; Sahashi, M.; Omori, T. [Kyoto Univ., Kyoto (Japan). Graduate School; Inoue, T. [Kyoto Univ., Kyoto (Japan)

    1996-06-15

    When steel is quenched, structures with high toughness are obtained due to the formation of martensite in materials, but on the other hand the tenacity is always defective. In this study, a velocity equation controlling the phase-changes through the whole process is proposed based on a metallo-thermo-mechanics theory for simulating the structure, temperature and stress in the heating-quenching-tempering process of steel. Further, a serial analysis of the water quenching-tempering process is carried out using a ring of S45C as the object of analysis. Especially, the effects of tempering temperature on the change of residual stresses are examined. The suitability of the analysis is verified since the results of temperature and stresses obtained from the analysis are almost in conformity with the experimental data. Although the structure change occurs in the tempering process at a low temperature (200{degree}C), the deformation is extremely small since the creep-deformation is hardly generated. The residual stresses after quenching is relaxed and remarkable tempering effects are shown when tempering is carried out at 600{degree}C. 14 refs., 17 figs.

  17. The Magnetization Reversal Processes Of Bulk (Nd, Y-(Fe, Co-B Alloy In The As-Quenched State

    Directory of Open Access Journals (Sweden)

    Dośpiał M.

    2015-09-01

    Full Text Available The magnetization reversal processes of bulk Fe64Co5Nd6Y6B19 alloy in the as-quenched state have been investigated. From the analysis of the initial magnetization curve and differential susceptibility versus an internal magnetic field it was deduced, that the main mechanism of magnetization reversal process is the pinning of domain walls at the grain’s boundaries of the Nd2Fe14B phase. Basing on the dependence of the reversible magnetization component as a function of magnetic field it was found that reversible rotation of a magnetic moment vector and motion of domain walls in multi-domain grains result in high initial values of the reversible component. The presence of at least two maxima on differential susceptibility of irreversible magnetization component in function of magnetic field imply existence of few pinning sites of domain walls in Fe64Co5Nd6Y6B19 alloy. The dominant interactions between particles have been determined on the basis of the Wohlfarth dependence. Such a behavior of Wohlfarth’s plot implies that the dominant interaction between grains becomes short range exchange interactions.

  18. Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

    Directory of Open Access Journals (Sweden)

    G. Magudeeswaran

    2014-03-01

    Full Text Available Quenched and Tempered (Q&T steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC in the heat affected zone (HAZ after welding. The use of austenitic stainless steel (ASS consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q&T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel (LHF consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q&T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding consumables and welding processes on fatigue crack growth behaviour of armour grade Q&T Steel joints. Shielded metal arc welding (SMAW and Flux cored arc welding (FCAW were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process using LHF consumable exhibited superior fatigue crack growth resistance than all other joints.

  19. Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

    Institute of Scientific and Technical Information of China (English)

    G. MAGUDEESWARAN; V. BALASUBRAMANIAN; G. MADHUSUDHAN REDDY

    2014-01-01

    Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC) in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel (ASS) consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q&T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel (LHF) consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q&T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding con-sumables and welding processes on fatigue crack growth behaviour of armour grade Q&T Steel joints. Shielded metal arc welding (SMAW) and Flux cored arc welding (FCAW) were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process using LHF consumable exhibited superior fatigue crack growth resistance than all other joints.

  20. LoCuSS: THE SLOW QUENCHING OF STAR FORMATION IN CLUSTER GALAXIES AND THE NEED FOR PRE-PROCESSING

    Energy Technology Data Exchange (ETDEWEB)

    Haines, C. P. [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Correo Central, Santiago (Chile); Pereira, M. J.; Egami, E.; Rawle, T. D. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Smith, G. P.; Ziparo, F.; McGee, S. L. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Babul, A. [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 1A1 (Canada); Finoguenov, A. [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-0014 Helsinki (Finland); Okabe, N. [Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan (China); Moran, S. M., E-mail: cphaines@das.uchile.cl [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-06-10

    We present a study of the spatial distribution and kinematics of star-forming galaxies in 30 massive clusters at 0.15 < z < 0.30, combining wide-field Spitzer 24 μm and GALEX near-ultraviolet imaging with highly complete spectroscopy of cluster members. The fraction (f{sub SF}) of star-forming cluster galaxies rises steadily with cluster-centric radius, increasing fivefold by 2r{sub 200}, but remains well below field values even at 3r{sub 200}. This suppression of star formation at large radii cannot be reproduced by models in which star formation is quenched in infalling field galaxies only once they pass within r{sub 200} of the cluster, but is consistent with some of them being first pre-processed within galaxy groups. Despite the increasing f{sub SF}-radius trend, the surface density of star-forming galaxies actually declines steadily with radius, falling ∼15× from the core to 2r{sub 200}. This requires star formation to survive within recently accreted spirals for 2–3 Gyr to build up the apparent over-density of star-forming galaxies within clusters. The velocity dispersion profile of the star-forming galaxy population shows a sharp peak of 1.44 σ{sub ν} at 0.3r{sub 500}, and is 10%–35% higher than that of the inactive cluster members at all cluster-centric radii, while their velocity distribution shows a flat, top-hat profile within r{sub 500}. All of these results are consistent with star-forming cluster galaxies being an infalling population, but one that must also survive ∼0.5–2 Gyr beyond passing within r{sub 200}. By comparing the observed distribution of star-forming galaxies in the stacked caustic diagram with predictions from the Millennium simulation, we obtain a best-fit model in which star formation rates decline exponentially on quenching timescales of 1.73 ± 0.25 Gyr upon accretion into the cluster.

  1. LoCuSS: The slow quenching of star formation in cluster galaxies and the need for pre-processing

    CERN Document Server

    Haines, C P; Smith, G P; Egami, E; Babul, A; Finoguenov, A; Ziparo, F; McGee, S L; Rawle, T D; Okabe, N; Moran, S M

    2015-01-01

    We present a study of the spatial distribution and kinematics of star-forming galaxies in 30 massive clusters at 0.15quenched in infalling field galaxies only once they pass within r200 of the cluster, but is consistent with some of them being first pre-processed within galaxy groups. Despite the increasing f_SF-radius trend, the surface density of star-forming galaxies actually declines steadily with radius, falling ~15x from the core to 2r200. This requires star-formation to survive within recently accreted spirals for 2--3Gyr to build up the apparent over-density of star-forming galaxies within clusters...

  2. Quench Simulation Studies: Program documentation of SPQR

    CERN Document Server

    Sonnemann, F

    2001-01-01

    Quench experiments are being performed on prototypes of the superconducting magnets and busbars to determine the adequate design and protection. Many tests can only be understood correctly with the help of quench simulations that model the thermo-hydraulic and electrodynamic processes during a quench. In some cases simulations are the only method to scale the experimental results of prototype measurements to match the situation of quenching superconducting elements in the LHC. This note introduces the theoretical quench model and the use of the simulation program SPQR (Simulation Program for Quench Research), which has been developed to compute the quench process in superconducting magnets and busbars. The model approximates the heat balance equation with the finite difference method including the temperature dependence of the material parameters. SPQR allows the simulation of longitudinal quench propagation along a superconducting cable, the transverse propagation between adjacent conductors, heat transfer i...

  3. Tree size and light availability increase photochemical instead of non-photochemical capacities of Nothofagus nitida trees growing in an evergreen temperate rain forest.

    Science.gov (United States)

    Coopman, Rafael E; Briceño, Verónica F; Corcuera, Luis J; Reyes-Díaz, Marjorie; Alvarez, Daniela; Sáez, Katherine; García-Plazaola, José I; Alberdi, Miren; Bravo, León A

    2011-10-01

    Nothofagus nitida (Phil.) Krasser (Nothofagaceae) regenerates under the canopy in microsites protected from high light. Nonetheless, it is common to find older saplings in clear areas and adults as emergent trees of the Chilean evergreen forest. We hypothesized that this shade to sun transition in N. nitida is supported by an increase in photochemical and non-photochemical energy dissipation capacities of both photosystems in parallel with the increase in plant size and light availability. To dissect the relative contribution of light environment and plant developmental stage to these physiological responses, the photosynthetic performance of both photosystems was studied from the morpho-anatomical to the biochemical level in current-year leaves of N. nitida plants of different heights (ranging from 0.1 to 7 m) growing under contrasting light environments (integrated quantum flux (IQF) 5-40 mol m(-2). Tree height (TH) and light environment (IQF) independently increased the saturated electron transport rates of both photosystems, as well as leaf and palisade thickness, but non-photochemical energy flux, photoinhibition susceptibility, state transition capacity, and the contents of D1 and PsbS proteins were not affected by IQF and TH. Spongy mesophyll thickness and palisade cell diameter decreased with IQF and TH. A(max), light compensation and saturation points, Rubisco and nitrogen content (area basis) only increased with light environment (IQF), whereas dark respiration (R(d)) decreased slightly and relative chlorophyll content was higher in taller trees. Overall, the independent effects of more illuminated environment and tree height mainly increased the photochemical instead of the non-photochemical energy flux. Regardless of the photochemical increase with TH, carbon assimilation only significantly improved with higher IQF. Therefore it seems that mainly acclimation to the light environment supports the phenotypic transition of N. nitida from shade to

  4. Numerical Simulation of Temperature and Stress Fields of Ti-Alloy Thin-well Barrel during Quenching Process

    Institute of Scientific and Technical Information of China (English)

    LIYan-zeng; YANMu-fu; WUKun

    2004-01-01

    The mathematical models have been established to describe the temperature and stress profiles in Ti6A14V cylinder during quenching. The residual stress and deformation of the workpiece can be predicted precisely based on ANSYS software. The simulated results show that the temperature of the divided element decreases faster at the edge than that at the internal of the workpiece during quenching from 1050 to 20℃. The largest temperature difference and dimension change in diameter are about 90~C and 4).935%, respectively. The position of largest tensile stress occurs around the edge of the cylinder.

  5. Numerical Simulation of Temperature and Stress Fields of Ti-Alloy Thin-well Barrel during Quenching Process

    Institute of Scientific and Technical Information of China (English)

    LI Yan-zeng; YAN Mu-fu; WU Kun

    2004-01-01

    The mathematical models have been established to describe the temperature and stress profiles in Ti6Al4V cylinder during quenching. The residual stress and deformation of the workpiece can be predicted precisely based on ANSYS software. The simulated results show that the temperature of the divided element decreases faster at the edge than that at the internal of the workpiece during quenching from 1050 to 20℃. The largest temperature difference and dimension change in diameter are about 90℃ and -0.935%, respectively. The position of largest tensile stress occurs around the edge of the cylinder.

  6. Simple replacement of violaxanthin by zeaxanthin in LHC-II does not cause chlorophyll fluorescence quenching.

    Science.gov (United States)

    Dreuw, Andreas; Wormit, Michael

    2008-03-01

    Recently, a mechanism for the energy-dependent component (qE) of non-photochemical quenching (NPQ), the fundamental photo-protection mechanism in green plants, has been suggested. Replacement of violaxanthin by zeaxanthin in the binding pocket of the major light harvesting complex LHC-II may be sufficient to invoke efficient chlorophyll fluorescence quenching. Our quantum chemical calculations, however, show that the excited state energies of violaxanthin and zeaxanthin are practically identical when their geometry is constrained to the naturally observed structure of violaxanthin in LHC-II. Therefore, since violaxanthin does not quench LHC-II, zeaxanthin should not either. This theoretical finding is nicely in agreement with experimental results obtained by femtosecond spectroscopy on LHC-II complexes containing violaxanthin or zeaxanthin.

  7. Electron-transfer fluorescence quenching processes in coaggregates between excited N-alkylcarbazoles as electron donors and 2, 4-dinitrophenyl carboxylates or pentafiuorophenyl carboxylates as acceptors

    Institute of Scientific and Technical Information of China (English)

    SHI, Ji-Liang; YI, Hu-Nan; XU, Jia-Yi; JIANG, Xi-Kui

    2000-01-01

    Electron-transfer processes facilitated by hydrophobiclipophilic interaction (HLI) between excited N-alkylcarbazoles (1-n, n=4, 8, 12, 16) as electron donors and 2,4dinnrophenyl carboxylates (2-n, n = 4, 8, 12, 16) or pentafluorophenyl carboxylates (3-n, n = 4, 8, 12, 16) as electron acceptors have been investigated by means of fluorescence spectroscopy in aqueous or aquiorgano binary mixtures.The fluorescence quenching of-n* by2-n or-n indicates that preassociation precedes the electron transfer. The extent of HLI-drtven coaggregation of the acceptor and the donor may be assessed from the B value of the equation I0/I = A + B [Q]. The chain-length effect and possibly also a chain-foldability effect, as well as the solvent aggregating power (SAgP)effect have been observed. Comparison of the quenching constants ( B ) for 1-n* /2-n combinations and 1-n* / 3-n combinations shows that the order of increasing B values for the quenching processes is 3-n < 2-n.

  8. Quenching star formation in cluster galaxies

    CERN Document Server

    Taranu, Dan S; Balogh, Michael L; Smith, Russell J; Power, Chris; Krane, Brad

    2012-01-01

    In order to understand the processes that quench star formation within rich clusters, we construct a library of subhalo orbits drawn from lambdaCDM cosmological N-body simulations of four rich clusters. The orbits are combined with models of star formation followed by quenching in the cluster environment to predict colours and spectroscopic line indices of satellite galaxies. Simple models with only halo mass-dependent quenching and without environmental (i.e. cluster-dependent) quenching fail to reproduce the observed cluster-centric colour and absorption linestrength gradients. Models in which star formation is instantly quenched at the virial radius also fail to match the observations. Better matches to the data are achieved by more complicated bulge-disc models in which the bulge stellar populations depend only on the galaxy subhalo mass while the disc quenching depends on the cluster environment. In the most successful models quenching begins at pericentre, operating on an exponential timescale of 2 -- 3...

  9. Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

    OpenAIRE

    G. Magudeeswaran; Balasubramanian, V.; G. Madhusudhan Reddy

    2014-01-01

    Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC) in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel (ASS) consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel ba...

  10. Microstructure and mechanical properties of a medium-carbon bainitic steel by a novel quenching and dynamic partitioning (Q-DP) process

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qiangguo; Huang, Xuefei; Huang, Weigang, E-mail: huangwg56@163.com

    2016-04-26

    A novel Quenching and Dynamic Partitioning (Q-DP) process for a 0.3C-1.4Si-1.8Mn-1.3Cr-0.3Mo (wt%) bainitic steel was developed and the microstructure and mechanical properties were investigated. The results show that the microstructure of the Q-DP treated steel consists of bainite, martensite and retained austenite, and it exhibit a better combination of tensile strength (above 1500 MPa), total elongation (above 17%) and impact toughness (above 90 J). Among the different Q-DP process, the sample treated by 250 °C Q-DP process exhibits the best combination of strength (1519 MPa), ductility (21.3%), the product of strength and elongation (PSE, 32.4 GPa%) and maximum impact toughness (108 J) compared to the quenching and partitioning (Q&P) process and other Q-DP processes. In addition, the work hardening behaviors of the Q&P and Q-DP samples were investigated. The stress-strain curves show that the Q&P and 250 °C Q-DP treated samples exhibit the larger uniform elongation and the value of n calculated for samples is 0.109 and 0.101 respectively.

  11. Effect of rapid heating, quenching and transformation conditions on the superconducting properties and microstructure of Jelly-Roll processed Nb3Al superconductors

    Science.gov (United States)

    Fukuzaki, T.; Takeuchi, T.; Banno, N.; Tagawa, K.; Tatsumi, N.; Ogiwara, H.; Wada, H.

    2002-10-01

    A Jelly-Roll processed Nb3Al superconductor with excellent superconducting properties has been fabricated by the process of rapid heating, quenching and transformation (RHQT). In order to fabricate a long length of wire with homogeneous superconducting properties, the optimization of the RHQT conditions is particularly important because RHQT conditions determine the final microstructure and superconducting properties. In this paper, we have studied the variation of microstructure and superconducting properties with RHQ and transformation annealing conditions, to determine the optimum processing condition. In the study of the RHQ treatment, we found that the RHQ conditions are divided into four regions according to the joule heating current (IRHQ). In the optimum region, the wire is quenched from the temperature in which a bcc solid solution extends to more than 25 at%Al, and the scatter of critical current density (Jc) after transformation annealing is almost negligible. In the study of the deformation and transformation heat treatment, we have found that the deformation of the supersaturated solid solution improves the resultant superconducting properties, and prevents degradation of superconducting properties that occurs when the temperature ramp-up rate is slow.

  12. Study on Quenching Process of Piston Rod Ball Head%活塞杆球头淬火工艺研究

    Institute of Scientific and Technical Information of China (English)

    白海明; 刘程; 屈海艳

    2015-01-01

    主要研究了30CrMnSi活塞杆球头淬火工艺。为减少球头的淬硬层深度,设计了冷却筒实验工装,通过调整工艺参数,并结合硬度测量和金相组织分析方法,研究结果表明:830±10°C淬火,水冷,淬硬层深度为10 mm,硬度值HRC35~40,完全满足设计要求。%Mainly studied the quenching process of the piston rod ball head in 30CrMnSi. In order to reduce the depth of the ball head hardened layer, the experiment equipment of the cooling cylinder was designed. By adjusting process parameters, and combined with the analytical method of hardness measurement and metallographic structure, results of the study showed that 830+10°C quenching, water cooling, depth of the hardening layer was 10 mm, and hardness value was HRC35~40, fully meeting the design requirements.

  13. The quenching time scale and quenching rate of galaxies

    CERN Document Server

    Lian, Jianhui; Zhang, Kai; Kong, Xu

    2016-01-01

    The average star formation rate (SFR) in galaxies has been declining since redshift of 2. A fraction of galaxies quench and become quiescent. We constrain two key properties of the quenching process: the quenching time scale and the quenching rate among galaxies. We achieve this by analyzing the galaxy number density profile in NUV-u color space and the distribution in NUV-u v.s. u-i color-color diagram with a simple toy-model framework. We focus on galaxies in three mass bins between 10 to 10 and 10 to 10.6 solar mass. In the NUV-u v.s. u-i color-color diagram, the red u-i galaxies exhibit a different slope from the slope traced by the star-forming galaxies. This angled distribution and the number density profile of galaxies in NUV-u space strongly suggest that the decline of the SFR in galaxies has to accelerate before they turn quiescent. We model this color-color distribution with a two-phase exponential decline star formation history. The models with an e-folding time in the second phase (the quenching p...

  14. Finite Element Simulation of Quenching Process for 7075 Al Alloy%7075铝合金锻件淬火热处理有限元模拟

    Institute of Scientific and Technical Information of China (English)

    吴垠; 江雄心

    2012-01-01

    采用Deform-3D有限元软件,对7075铝合金锻件淬火热处理过程进行了数值模拟,讨论了固溶温度及淬火介质温度对淬火后残余应力的影响.结果表明:残余应力呈现表层受压、芯部受拉的分布:通过提高淬火介质温度或降低固溶温度可降低材料在淬火过程中产生的残余应力.%Numerical simulation of quenching process for 7075 Al-alloy forging was performed via Defrom-3D. The influences of temperature in solution treatment and qunechant temperature were discussed. The results show that the residual stress pattern consists of compressive stress at the surface and tensile stress at the center of the workpiece. In addition, the residual stress reduces with the decrease of solution treatment temperature or with the increase of quenching medium temperature.

  15. Fluorescence quenching of TMR by guanosine in oligonucleotides

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Nucleotide-specific fluorescence quenching in fluorescently labeled DNA has many applications in biotechnology. We have studied the inter-and intra-molecular quenching of tetramethylrhodamine (TMR) by nucleotides to better understand their quenching mechanism and influencing factors. In agreement with previous work, dGMP can effectively quench TMR, while the quenching of TMR by other nucleotides is negligible. The Stern-Volmer plot between TMR and dGMP delivers a bimolecular quenching constant of Ks=52.3 M-1. The fluorescence of TMR in labeled oligonucleotides decreases efficiently through photoinduced electron transfer by guanosine. The quenching rate constant between TMR and guanosine was measured using fluorescence correlation spectroscopy (FCS). In addition, our data show that the steric hindrance by bases around guanosine has significant effect on the G-quenching. The availability of these data should be useful in designing fluorescent oligonucleotides and understanding the G-quenching process.

  16. Single photon detection with self-quenching multiplication

    Science.gov (United States)

    Zheng, Xinyu (Inventor); Cunningham, Thomas J. (Inventor); Pain, Bedabrata (Inventor)

    2011-01-01

    A photoelectronic device and an avalanche self-quenching process for a photoelectronic device are described. The photoelectronic device comprises a nanoscale semiconductor multiplication region and a nanoscale doped semiconductor quenching structure including a depletion region and an undepletion region. The photoelectronic device can act as a single photon detector or a single carrier multiplier. The avalanche self-quenching process allows electrical field reduction in the multiplication region by movement of the multiplication carriers, thus quenching the avalanche.

  17. Non-linear effects of initial melt temperatures on microstructures and mechanical properties during quenching process of liquid Cu46Zr54 alloy

    Science.gov (United States)

    Mo, Yun-Fei; Liu, Rang-Su; Tian, Ze-An; Liang, Yong-Chao; Zhang, Hai-Tao; Hou, Zhao-Yang; Liu, Hai-Rong; Zhang, Ai-long; Zhou, Li-Li; Peng, Ping; Xie, Zhong

    2015-05-01

    A MD simulation of liquid Cu46Zr54 alloys has been performed for understanding the effects of initial melt temperatures on the microstructural evolution and mechanical properties during quenching process. By using several microstructural analyzing methods, it is found that the icosahedral and defective icosahedral clusters play a key role in the microstructure transition. All the final solidification structures obtained at different initial melt temperatures are of amorphous structures, and their structural and mechanical properties are non-linearly related to the initial melt temperatures, and fluctuated in a certain range. Especially, there exists a best initial melt temperature, from which the glass configuration possesses the highest packing density, the optimal elastic constants, and the smaller extent of structural softening under deforming.

  18. Vertical lathe ram sliding guide surface intermediate frequency quenching process research%立车滑枕滑动导轨面中频淬火工艺研究

    Institute of Scientific and Technical Information of China (English)

    张宇巍

    2013-01-01

    Through the research test track vertical lathe various specifications ram guide plane class and rectangular face kind of intermediate frequency quenching process, summarizes the intermediate frequency quenching process parameters and quality inspection results.%  通过研究试验跟踪立车各种规格滑枕导轨平面类及直角面类中频淬火工艺,归纳总结出中频淬火工艺参数及质量检验结果。

  19. Finite Element Simulation of Metal Quenching

    Institute of Scientific and Technical Information of China (English)

    方刚; 曾攀

    2004-01-01

    The evolution of the phase transformation and the resulting internal stresses and strains in metallic parts during quenching were modeled numerically. The numerical simulation of the metal quenching process was based on the metallo-thermo-mechanical theory using the finite element method to couple the temperature, phase transformation, and stress-strain fields. The numerical models are presented for the heat treatment and kinetics of the phase transformation. The finite element models and the phase transition kinetics accurately predict the distribution of the microstructure volume fractions, the temperature, the distortion, and the stress-strain relation during quenching. The two examples used to validate the models are the quenching of a small gear and of a large turbine rotor. The simulation results for the martensite phase volume fraction, the stresses, and the distortion in the gear agree well with the experimental data. The models can be used to optimize the quenching conditions to ensure product quality.

  20. Numerical simulation on vacuum solution heat treatment and gas quenching process of a low rhenium-containing Ni-based single crystal turbine blade

    Directory of Open Access Journals (Sweden)

    Zhe-xin Xu

    2016-11-01

    Full Text Available Numerical heat-transfer and turbulent flow model for an industrial high-pressure gas quenching vacuum furnace was established to simulate the heating, holding and gas fan quenching of a low rhenium-bearing Ni-based single crystal turbine blade. The mesh of simplified furnace model was built using finite volume method and the boundary conditions were set up according to the practical process. Simulation results show that the turbine blade geometry and the mutual shielding among blades have significant influence on the uniformity of the temperature distribution. The temperature distribution at sharp corner, thin wall and corner part is higher than that at thick wall part of blade during heating, and the isotherms show a toroidal line to the center of thick wall. The temperature of sheltered units is lower than that of the remaining part of blade. When there is no shelteration among multiple blades, the temperature distribution for all blades is almost identical. The fluid velocity field, temperature field and cooling curves of the single and multiple turbine blades during gas fan quenching were also simulated. Modeling results indicate that the loading tray, free outlet and the location of turbine blades have important influences on the flow field. The high-speed gas flows out from the nozzle is divided by loading tray, and the free outlet enhanced the two vortex flow at the end of the furnace door. The closer the blade is to the exhaust outlet and the nozzle, the greater the flow velocity is and the more adequate the flow is. The blade geometry has an effect on the cooling for single blade and multiple blades during gas fan quenching, and the effects in double layers differs from that in single layer. For single blade, the cooing rate at thin-walled part is lower than that at thick-walled part, the cooling rate at sharp corner is greater than that at tenon and blade platform, and the temperature at regions close to the internal position is

  1. Temperature Profiles During Quenches in LHC Superconducting Dipole Magnets Protected by Quench Heaters

    CERN Document Server

    Maroussov, V; Siemko, A

    2000-01-01

    The efficiency of the magnet protection by quench heaters was studied using a novel method which derives the temperature profile in a superconducting magnet during a quench from measured voltage signals. In several Large Hadron Collider single aperture dipole models, temperature profiles and temperature gradients in the magnet coil have been evaluated in the case of protection by different sets of quench heaters and different powering and protection parameters. The influence of the insulation thickness between the quench heaters and the coil has also been considered. The results show clear correlation between the positions of quench heaters, magnet protection parameters and temperature profiles. This study allowed a better understanding of the quench process mechanisms and the efficiency assessment of the different protection schemes.

  2. Quench Protection and Magnet Supply Requirements for the MICEFocusingand Coupling Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Green, Michael A.; Witte, Holger

    2005-06-08

    This report discusses the quench protection and power supply requirements of the MICE superconducting magnets. A section of the report discusses the quench process and how to calculate the peak voltages and hotspot temperature that result from a magnet quench. A section of the report discusses conventional quench protection methods. Thermal quench back from the magnet mandrel is also discussed. Selected quench protection methods that result in safe quenching of the MICE focusing and coupling magnets are discussed. The coupling of the MICE magnets with the other magnets in the MICE is described. The consequences of this coupling on magnet charging and quenching are discussed. Calculations of the quenching of a magnet due quench back from circulating currents induced in the magnet mandrel due to quenching of an adjacent magnet are discussed. The conclusion of this report describes how the MICE magnet channel will react when one or magnets in that channel are quenched.

  3. NUMERICAL SIMULATION OF HEATING AND QUENCHING PROCESSES FOR A 280 CONNECTING ROD OF 16V280ZJ DIESEL LOCOMOTIVE

    Institute of Scientific and Technical Information of China (English)

    J.S. Ye; Z.R. Ye; A. Yang; Y. Luo

    2002-01-01

    A modified temperature-phase transformation-stress coupled 3D non-linear mathemat-ical model and a series of subroutines on the non-liner MARC (MARC Analysis Re-search Corporation) are developed. Then this modified model has been utilized to simu-late the heat treatment processes of 280 connecting rod of 16V280ZJ diesel locomotive.The simulation results are basically in agreement with the experiments, which testifythat the mathematical model and method are feasible. In addition, the simulationcan not only obtain the transient temperature and microstructure of heat treatmentprocess, but also provide a sound scientific basis for the heat treatment workers.

  4. COMPUTER-AID ANALYSIS FOR CRACKING OF 280 CONNECTING ROD OF 16V280ZJ DIESEL LOCOMOTIVE ON QUENCHING PROCESS

    Institute of Scientific and Technical Information of China (English)

    J.S. Ye; A. Yang; Y. Luo

    2004-01-01

    280 connecting rod is one of the most important parts for 16V280ZJ diesel locomotive, so it needs much better mechanical performance. However, the crack is often generated at the middle section of connecting rod body on heat treatment process. A temperature-phase transformation-stress coupled 3D non-linear mathematical model has been developed to analyze the reasons of cracking. The simulation and experimental results show that the compressive stress on the cracking position is close to the fracture stress of connecting rod and the reasons of crack are mainly contributed to the carbon content excess of original material or the aging of quenchant.

  5. Microstructure and corrosion behavior of a Zr-Sn-Nb-Fe-Cu-O alloy fabricated by α+β quenching processing

    Science.gov (United States)

    Chen, Liangyu; Zhang, Lina; Chai, Linjiang; Yang, Wenlong; Wang, Liqiang; lu, Weijie

    2017-03-01

    In this work, the microstructure of a Zr-Sn-Nb-Fe-Cu-O alloy fabricated by α+β quenching processing (ABQ sample) was investigated by the combined utilization of scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. The results showed that the polygonal grains evenly distributed in ABQ sample and triangular grains distributed at triple junctions of polygonal grains with densely second phase particles (SPPs). The textures of directions tilted approximately 25° from normal direction and the rolling direction spreading along the {-} were found in the sample, which was also detected in the regularly cold rolled and annealed sample. The occurrence of corrosion kinetics transition of ABQ sample was sight earlier than that of RAX sample. Due to a higher solid solubility of β-Zr, SPPs re-dissolved into β-Zr during α+β annealing and precipitated out afterward in those areas. Finally, discrepant corrosion rate of metal matrix and SPPs led to the formation of protrusions of matrix, which could concentrate stress and generate cracks in the oxide.

  6. Numerical simulation and experimental study of a new material during its quenching process%一种新型材料淬火过程的数值模拟和实验研究

    Institute of Scientific and Technical Information of China (English)

    张世珍; 王维锐; 李玉良; 杨文伟; 颜益

    2013-01-01

    Aiming at the current quenching process status of a new type of motorcycle brake disc special materials B410DB which is based on artificial experience and small batch trial production, its quenching process's numerical simulation and temperature experiment were carried out and it's temperature and mi-crostructure fields were analyzed. Through the material performance simulation software JMatPro, the mechanical, thermal physical properties and the time temperature transformation (TTT) curve, the continuous cooling transformation CCT curve of B410DB were given. Based on the quenching process,and u-sing heat treatment professional software DEFORM, a finite element model (FEM) was developed to indicate the brake disc actual quenching process. The FEM was used to successfully simulate the temperature field and the change of the organization process of a certain type of brake disc. Simulation and experiment at results show that the FEM not only is accurate and feasible, but also can provide evidence for optimizing the quenching process; This method can be generally used for the quenching process of other materials and types of brake disc.%一种新型摩托车制动盘专用材料B410DB的淬火工艺目前仍采用人工经验和小批量试制的方法,针对这一现状,对该新型材料的淬火过程进行了数值模拟、温度实验和温度场、组织场的分析.运用材料性能模拟软件JMatPro得到了B410DB的机械、热物理性能及其等温转变曲线(TTT)、连续冷却转变曲线(CCT),在此基础上,利用热处理专业软件DEFORM,建立了能够反应制动盘实际淬火过程的数值模型.利用该数值模型模拟了某型号制动盘的温度场和组织场的变化过程.仿真和实验结果对比表明:该模型准确可行,温度变化和组织状态与实验吻合度高,为优化制动盘淬火过程提供了依据,该方法也可用于其他材料和型号的制动盘淬火过程,具有一定的通用性.

  7. Quenching: fact or fiction?

    Science.gov (United States)

    Basketter, D

    2000-11-01

    Fragrance chemicals are a frequently reported cause of allergic contact dermatitis (ACD), a matter which has recently come into considerable prominence, to the point that legislation in Europe is under serious consideration. Certain skin-sensitizing fragrance chemicals have been reported by the producing industry to be rendered safe (quenched), at least in terms of ACD, when they are used in the presence of a specific quenching agent. Accordingly, it seemed timely to review this apparent quenching phenomenon, considering the available data and potential mechanistic hypotheses that might be used to explain it. If it is correct, it should be a phenomenon of potentially enormous value in the elimination of the allergenic properties of at least a proportion of common skin sensitizers. Whilst there is some evidence in man for the occurrence of quenching during the induction of skin sensitization, a much more substantial body of work has failed to find supportive evidence in various animals models, at a chemical level or at elicitation in human subjects with existing allergy. On balance, it is concluded that quenching of fragrance allergens is a phenomenon still awaiting positive evidence of existence.

  8. Numerical Simulation on Carburizing and Quenching of Gear Ring

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The carburizing process of the gear ring was simulated by taking into account the practical carburizing and quenching techniques of the gear ring and by solving the diffusion equation. The carbon content distribution in the carburized layer was obtained. Based on the results, the quenching process of the gear ring was then simulated using the metallic thermodynamics and FEM; it was found that the carburization remarkably affects the quenching process.Microstructures and stress distributions of the gear ring in the quenching process were simulated, and the results are confirmed by experiments.

  9. Inhomogeneous Thermal Quenches

    CERN Document Server

    Sohrabi, Kiyoumars A

    2015-01-01

    We describe holographic thermal quenches that are inhomogeneous in space. The main characteristic of the quench is to take the system far from its equilibrium configuration. Except special extreme cases, the problem has no analytic solution. Using the numerical holography methods, we study different observables that measure thermalization such as the time evolution of the horizon, two-point Wightman function and entanglement entropy (EE). Having an extra nontrivial spacial direction, allows us to study this peculiar generalization since we categorize the problem based on whether we do the measurements along this special direction or perpendicular to it. Exciting new features appear that are absent in the common computations in the literature, the appearance of negative EE valleys surrounding the positive EE hills and abrupt quenches that occupy the whole space at their universal limit are some of the results of this paper. We have tried to provide physical explanations wherever possible. The physical picture ...

  10. The Quench Action

    Science.gov (United States)

    Caux, Jean-Sébastien

    2016-06-01

    We give a pedagogical introduction to the methodology of the Quench Action, which is an effective representation for the calculation of time-dependent expectation values of physical operators following a generic out-of-equilibrium state preparation protocol (for example a quantum quench). The representation, originally introduced in Caux and Essler (2013 Phys. Rev. Lett. 110 257203), is founded on a mixture of exact data for overlaps together with variational reasonings. It is argued to be quite generally valid and thermodynamically exact for arbitrary times after the quench (from short times all the way up to the steady state), and applicable to a wide class of physically relevant observables. Here, we introduce the method and its language, give an overview of some recent results, suggest a roadmap and offer some perspectives on possible future research directions.

  11. Quantum quenches during inflation

    CERN Document Server

    Carrilho, Pedro

    2016-01-01

    We propose a new technique to study fast transitions during inflation, by studying the dynamics of quantum quenches in an $O(N)$ scalar field theory in de Sitter spacetime. We compute the time evolution of the system using a non-perturbative large-$N$ limit approach. We derive the self-consistent mass equation for several physically relevant transitions of the parameters of the theory, in a slow motion approximation. Our computations reveal that the effective mass after the quench evolves in the direction of recovering its value before the quench, but stopping at a different asymptotic value, in which the mass is strictly positive. Furthermore, we tentatively find situations in which the effective mass can be temporarily negative, thus breaking the $O(N)$ symmetry of the system for a certain time, only to then come back to a positive value, restoring the symmetry. We argue the relevance of our new method in a cosmological scenario.

  12. "Super-quenching" state protects Symbiodinium from thermal stress - Implications for coral bleaching.

    Science.gov (United States)

    Slavov, Chavdar; Schrameyer, Verena; Reus, Michael; Ralph, Peter J; Hill, Ross; Büchel, Claudia; Larkum, Anthony W D; Holzwarth, Alfred R

    2016-06-01

    The global rise in sea surface temperatures causes regular exposure of corals to high temperature and high light stress, leading to worldwide disastrous coral bleaching events (loss of symbiotic dinoflagellates (Symbiodinium) from reef-building corals). Our picosecond chlorophyll fluorescence experiments on cultured Symbiodinium clade C cells exposed to coral bleaching conditions uncovered the transformations of the alga's photosynthetic apparatus (PSA) that activate an extremely efficient non-photochemical "super-quenching" mechanism. The mechanism is associated with a transition from an initially heterogeneous photosystem II (PSII) pool to a homogeneous "spillover" pool, where nearly all excitation energy is transferred to photosystem I (PSI). There, the inherently higher stability of PSI and high quenching efficiency of P(700)(+) allow dumping of PSII excess excitation energy into heat, resulting in almost complete cessation of photosynthetic electron transport (PET). This potentially reversible "super-quenching" mechanism protects the PSA against destruction at the cost of a loss of photosynthetic activity. We suggest that the inhibition of PET and the consequent inhibition of organic carbon production (e.g. sugars) in the symbiotic Symbiodinium provide a trigger for the symbiont expulsion, i.e. bleaching.

  13. Eco-friendly luminescent solar concentrators with low reabsorption losses and resistance to concentration quenching based on aqueous-solution-processed thiolate-gold nanoclusters

    Science.gov (United States)

    Huang, H. Y.; Cai, K. B.; Chang, L. Y.; Chen, P. W.; Lin, T. N.; Lin, C. A. J.; Shen, J. L.; Talite, M. J.; Chou, W. C.; Yuan, C. T.

    2017-09-01

    Heavy-metal-containing quantum dots (QDs) with engineered electronic states have been served as luminophores in luminescent solar concentrators (LSCs) with impressive optical efficiency. Unfortunately, those QDs involve toxic elements and need to be synthesized in a hazardous solvent. Recently, biocompatible, eco-friendly gold nanoclusters (AuNCs), which can be directly synthesized in an aqueous solution, have gained much attention for promising applications in ‘green photonics’. Here, we explored the solid-state photophysical properties of aqueous-solution-processed, glutathione-stabilized gold nanoclusters (GSH-AuNCs) with a ligand-to-metal charge-transfer (LMCT) state for developing ‘green’ LSCs. We found that such GSH-AuNCs exhibit a large Stokes shift with almost no spectral overlap between the optical absorption and PL emission due to the LMCT states, thus, suppressing reabsorption losses. Compared with GSH-AuNCs in solution, the photoluminescence quantum yields (PL-QYs) of the LSCs can be enhanced, accompanied with a lengthened PL lifetime owing to the suppression of non-radiative recombination rates. In addition, the LSCs do not suffer from severe concentration-induced PL quenching, which is a common weakness for conventional luminophores. As a result, a common trade-off between light-harvesting efficiency and solid-state PL-QYs can be bypassed due to nearly-zero spectral overlap integral between the optical absorption and PL emission. We expect that GSH-AuNCs hold great promise for serving as luminophores for ‘green’ LSCs by further enhancing solid-state PL-QYs.

  14. The surprising inefficiency of dwarf satellite quenching

    CERN Document Server

    Wheeler, Coral; Cooper, Michael C; Boylan-Kolchin, Mike; Bullock, James S

    2014-01-01

    We study dwarf satellite galaxy quenching using observations from the Geha et al. (2012) NSA/SDSS catalog together with LCDM cosmological simulations to facilitate selection and interpretation. We show that fewer than 30% of dwarfs (M* ~ 10^8.5-10^9.5 Msun) identified as satellites within massive host halos (Mhost ~ 10^12.5-10^14 Msun) are quenched, in spite of the expectation from simulations that half of them should have been accreted more than 6 Gyr ago. We conclude that whatever the action triggering environmental quenching of dwarf satellites, the process must be highly inefficient. We investigate a series of simple, one-parameter quenching models in order understand what is required to explain the low quenched fraction and conclude that either the quenching timescale is very long (> 9.5 Gyr, a "slow starvation" scenario) or that the environmental trigger is not well matched to accretion within the virial volume. We discuss these results in light of the fact that most of the low mass dwarf satellites in ...

  15. 重型载重车前轴分层淬火工艺仿真分析%Simulation analysis of layer by layer quenching process of a heavy truck front axle

    Institute of Scientific and Technical Information of China (English)

    朱振华; 秦训鹏; 高恺; 陈绪梁

    2016-01-01

    针对重型载重车前轴在传统整体式淬火强化后各部位马氏体含量、力学性能不均匀的问题,提出一种分层淬火工艺,并利用数值分析方法对某重型载重车前轴在分层淬火工艺条件下的温度场和微观组织进行仿真计算。计算结果证明分层淬火工艺能使截面尺寸变化大的前轴在淬火冷却过程中有效改善马氏体分布不均匀现象,提高其综合力学性能。%For the nonuniformity of martensite content and mechanical properties in each part of a heavy truck front axle after traditional integral hardening, a layer by layer quenching process was presented. Temperature field and microstructure content in a heavy truck front axle under the quenching process were calculated by numerical simulation analysis. The calculated results show that the layer by layer quenching process can improve the nonuniformity of martensite distribution in the front axle with large varying of cross section and enhance the comprehensive mechanical properties.

  16. Design and Realization of Immediate Quenching Process Control System of Rail Section Plant of Pangang%攀钢轨梁余热淬火过程控制系统设计与实现

    Institute of Scientific and Technical Information of China (English)

    刘继光

    2012-01-01

    为了实现余热淬火线与整体产销和新轨梁L2.5系统间的信息集成,解决余热淬火线的信息孤岛问题,提出建立轨梁100m余热淬火过程控制系统.通过对数据库技术、插件技术、多线程技术和OPC技术的综合应用,成功建立余热淬火过程控制系统.该过程控制系统的建立,不仅实现了余热淬火与整体产销和新轨梁L2.5信息的无缝集成,生产数据的实时共享,生产过程的在线监视,而且对于提升轨梁厂的信息化水平具有重要作用.%In order to implement the information integration of residual heat quenching production line, integral produce and sale, new beam-and-rail L2.5 system, solving the problem of information isolated island in immediate quenching production line, an immediate quenching process control system along with 100 meter beam-and-rail was proposed. The above system was successfully established with the combination of database, plug-in, multithread and OPC technology. The establishment of this process control system not only realizes seamless integration of information from immediate heat quenching, integral produce and sale, new beam-and-rail L2.5 system, sharing production data in real time, on line monitoring of production process, but also plays a vital role for promoting the informationi level in rail section plant.

  17. Optimising Gas Quenching Technology through Modelling of Heat Transfer

    Institute of Scientific and Technical Information of China (English)

    Florent Chaffotte; Linda L(e)fevre; Didier Domergue; Aymeric Goldsteinas; Xavier Doussot; Qingfei Zhang

    2004-01-01

    Gas Quenching represents an environmentally friendly alternative to more commonly-used oil quenching. Yet,the performances of this technology remain limited in terms of cooling rates reached compared to oil quenching. Distortion and process homogeneity also have to be controlled carefully. The efficiency of the gas quenching process fully depends on the heat transfer between the gas and the quenched parts. The goal of this study is the optimisation of the gas quenching process efficiency through a better understanding of the heat transfer phenomena involved. The study has been performed with modelling means and validated by an experimental approach. The configuration of the gas flow has a major influence on the heat transfer phenomena between the gas and the parts. The fluid dynamics modelling approach performed in this study allows to optimise the heat transfer phenomena. New gas quenching processes allowing enhanced gas quenching performance through higher cooling rates can be thereby identified. The new solutions have been validated in experimental and industrial conditions. Results obtained allow to expect significant improvement of high pressure gas quenching technology.

  18. Optimising Gas Quenching Technology through Modelling of Heat Transfer

    Institute of Scientific and Technical Information of China (English)

    FiorentChaffotte; LindaLefevre; DidierDomergue; AymericGoidsteinas; XavierDoussot; QingfeiZhang

    2004-01-01

    Gas Quenching represents an environmentally friendly alternative to more commonly-used oil quenching. Yet,the performances of this technology remain limited in terms of cooling rates reached compared to oil quenching. Distortion and process homogeneity also have to be controlled carefully. The efficiency of the gas quenching process fully depends on the heat transfer between the gas and the quenched parts. The goal of this study is the optimisation of the gas quenching process efficiency through a better understanding of the heat transfer phenomena involved. The study has been performed with modelling means and validated by an experimental approach. ThE configuration of the gas flow has a major influence on the heat transfer phenomena between the gas and the parts. The fluid dynamics modelling approach performed in this study allows to optimise the heat transfer phenomena. New gas quenching processes allowing enhanced gas quenching performance through higher cooling rates can be thereby identified. The new solutions have been validated in experimental and industrial conditions. Results obtained allow to expect significant improvement of high pressure gas quenching technology.

  19. Application of PM Polymer Medium in Quenching Process for 42CrMo Steel%PM聚合物介质在42CrMo钢淬火中的应用

    Institute of Scientific and Technical Information of China (English)

    郑兴文

    2001-01-01

    为解决石油设备空心管强韧性不足问题,通过改变传统冷却方法,对不同尺寸42CrMo钢管在PM聚合物介质中进行了淬火试验,对其力学性能作了分析比较,获得42CrMo钢在PM聚合物介质中淬火的最佳工艺。%In order to improve strength and toughness of 42CrMo steel drill pipe,after quenching of the drill pipe samples in different size in polymer aqua-solution,the mechanical properties of the samples were analyzed,finally we obtained the optimal quenching process in PM polymer solution.

  20. Quench studies of ILC cavities

    Energy Technology Data Exchange (ETDEWEB)

    Eremeev, Grigory; Geng, Rongli; Palczewski, Ari; Dai, Jin

    2011-07-01

    Quench limits accelerating gradient in SRF cavities to a gradient lower than theoretically expected for superconducting niobium. Identification of the quenching site with thermometry and OST, optical inspection, and replica of the culprit is an ongoing effort at Jefferson Lab aimed at better understanding of this limiting phenomenon. In this contribution we present our finding with several SRF cavities that were limited by quench.

  1. Quenched effective population size

    CERN Document Server

    Sagitov, Serik; Vatutin, Vladimir

    2010-01-01

    We study the genealogy of a geographically - or otherwise - structured version of the Wright-Fisher population model with fast migration. The new feature is that migration probabilities may change in a random fashion. Applying Takahashi's results on Markov chains with random transition matrices, we establish convergence to the Kingman coalescent, as the population size goes to infinity. This brings a novel formula for the coalescent effective population size (EPS). We call it a quenched EPS to emphasize the key feature of our model - random environment. The quenched EPS is compared with an annealed (mean-field) EPS which describes the case of constant migration probabilities obtained by averaging the random migration probabilities over possible environments.

  2. Calculating Quenching Weights

    CERN Document Server

    Salgado, C A; Salgado, Carlos A.; Wiedemann, Urs Achim

    2003-01-01

    We calculate the probability (``quenching weight'') that a hard parton radiates an additional energy fraction due to scattering in spatially extended QCD matter. This study is based on an exact treatment of finite in-medium path length, it includes the case of a dynamically expanding medium, and it extends to the angular dependence of the medium-induced gluon radiation pattern. All calculations are done in the multiple soft scattering approximation (Baier-Dokshitzer-Mueller-Peign\\'e-Schiff--Zakharov ``BDMPS-Z''-formalism) and in the single hard scattering approximation (N=1 opacity approximation). By comparison, we establish a simple relation between transport coefficient, Debye screening mass and opacity, for which both approximations lead to comparable results. Together with this paper, a CPU-inexpensive numerical subroutine for calculating quenching weights is provided electronically. To illustrate its applications, we discuss the suppression of hadronic transverse momentum spectra in nucleus-nucleus colli...

  3. Phenomenology of Holographic Quenches

    Science.gov (United States)

    da Silva, Emilia; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2015-10-01

    We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals.

  4. Dynamical quenching of tunneling in molecular magnets

    Energy Technology Data Exchange (ETDEWEB)

    José Santander, María, E-mail: maria.jose.noemi@gmail.com [Recursos Educativos Quántica, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Roldán-Molina, A. [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Curauma, Valparaíso (Chile); Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso (Chile)

    2015-12-15

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation. - Highlights: • Single molecular magnets under rapidly oscillating magnetic fields is studied. • It is shown that this system displays the quenching of tunneling processes. • Our findings provide a control of quantum molecular magnets via terahertz radiation.

  5. Rapid sample processing for intracellular metabolite studies in Penicillium ochrochloron CBS 123.824: the FiltRes-device combines cold filtration of methanol quenched biomass with resuspension in extraction solution.

    Science.gov (United States)

    Vrabl, Pamela; Artmann, Desiree J; Schinagl, Christoph W; Burgstaller, Wolfgang

    2016-01-01

    Many issues concerning sample processing for intracellular metabolite studies in filamentous fungi still need to be solved, e.g. how to reduce the contact time of the biomass to the quenching solution in order to minimize metabolite leakage. Since the required time to separate the biomass from the quenching solution determines the contact time, speeding up this step is thus of utmost interest. Recently, separation approaches based on cold-filtration were introduced as promising alternative to cold-centrifugation, which exhibit considerably reduced contact times. In previous works we were unable to obtain a compact pellet from cold methanol quenched samples of the filamentous fungus Penicillium ochrochloron CBS 123.824 via centrifugation. Therefore our aim was to establish for this organism a separation technique based on cold-filtration to determine intracellular levels of a selected set of nucleotides. We developed a cold-filtration based technique as part of our effort to revise the entire sample processing method and analytical procedure. The Filtration-Resuspension (FiltRes) device combined in a single apparatus (1) a rapid cold-filtration and (2) a rapid resuspension of the biomass in hot extraction solution. Unique to this is the injection of the extraction solution from below the membrane filter (FiltRes-principle). This caused the mycelial cake to detach completely from the filter membrane and to float upwards so that the biomass could easily be transferred into preheated tubes for metabolite extraction. The total contact time of glucose-limited chemostat mycelium to the quenching solution could be reduced to 15.7 ± 2.5 s, whereby each washing step added another 10-15 s. We evaluated critical steps like filtration time, temperature profile, reproducibility of results, and using the energy charge (EC) as a criterion, effectiveness of enzyme destruction during the transition in sample temperature from cold to hot. As control we used total broth samples

  6. 基于正交试验的端帽激光淬火工艺研究%Laser Quenching Process Research of End Cap Based on Orthogonal Test

    Institute of Scientific and Technical Information of China (English)

    贺敬地; 王斌修

    2011-01-01

    In laser quenching research for automatic balancing valve over-current end cap surface, the factors of influence are studied on laser quenching by using orthogonal experiment. The best parameters of laser quenching and the influence law on the surface hardness and hardening layer depth of layer machined by laser duing to pulse current, scanning velocity and from focal quantity are drawn. The experimental results show that as long as the appropriate laser parameters be chosen, good surface hardening quality can be obtained. These provide theoretical guidance for laser processing.%对自动流量平衡阀过流端帽的表面进行激光淬火研究,利用正交试验对影响激光淬火的因素进行了研究,得出激光淬火的最佳参数以及脉冲电流、扫描速度和离焦量对激光表面硬度和淬硬层深度的影响规律.试验结果表明,只要工艺参数选择适当,可获得很好的表面淬火质量,为激光加工提供了理论指导.

  7. Quenching of fluorescence in membrane protein by hypocrellin B.

    Science.gov (United States)

    Yue, J; Pang, S

    1997-04-01

    The hypocrellin B (HB) was used as a fluorescence quencher to study the basic physical charactcristics of HB in membrane systems, including the diffusion speed of quencher from aqueous phase into membrane phase, the partition coefficient (P) of quenchtr between membrane and water, and the fluorescence quenching constant of protein (K(sv); K(q),). The experimental results show that the quenching of fluorescence in membrane protein by HB can be determined by the principle of dynamic quenching. The experimental process of fluorescence quenching was observed in detail by using the ESR technique. The signal of HB- was found to arise from an electron transfer from excited trytophan to HB.

  8. Quenching of fluorescence in membrane protein by hypocrellin B

    Institute of Scientific and Technical Information of China (English)

    乐加昌; 庞素珍

    1997-01-01

    The hypocrellin B (HB) was used as a fluorescence quencher to study the basic physical characteris-tics of HB in membrane systems, including the diffusion speed of quencher from aqueous phase into membrane phase, the partition coefficient (P) of quencher between membrane and water, and the fluorescence quenching constant of protein (Ksv; Kq). The experimental results show that the quenching of fluorescence in membrane protein by HB can be determined by the principle of dynamic quenching. The experimental process of fluorescence quenching was ob-served in detail by using the ESR technique. The signal of HB" was found to arise from an electron transfer from ex-cited trytophan to HB.

  9. Experimental methods for quenching structures in lunar-analog silicate melts: Variations as a function of quench media and composition

    Science.gov (United States)

    Dyar, M. D.

    1985-01-01

    Compositions analogous to lunar green, organge, and brown glasses were synthesized under consistent conditions, then quenched into a variety of different media when the samples were removed from the furnace. Iron valence and coordination are a direct function of quench media used, spanning the range from brine/ice (most effective quench), water, butyl phthalate, silicone oil, liquid nitrogen, highly reducing CO-CO2 gas, to air (least efficient quench). In the green and brown glasses, Fe(3+) in four-fold and six-fold coordination is observed in the slowest-quenched samples; Fe(2+) coordination varies directly with quench efficiency. Less pronounced changes were observed in the Ti-rich orange glass. Therefore the remote-sensed spectrum of a glass-bearing regolith on the Moon may be influenced by the process by which the glass cooled, and extreme caution must be used when comparing spectra of synthetic glass analogs with real lunar glasses.

  10. Experimental methods for quenching structures in lunar-analog silicate melts - Variations as a function of quench media and composition

    Science.gov (United States)

    Dyar, M. D.

    1984-01-01

    Compositions analogous to lunar green, orange, and brown glasses were synthesized under consistent conditions, then quenched into a variety of different media when the samples were removed from the furnace. Iron valence and coordination are a direct function of quench media used, spanning the range from brine/ice (most effective quench), water, butyl phthalate, silicone oil, liquid nitrogen, highly reducing CO-CO2 gas, to air (least efficient quench). In the green and brown glasses, Fe(3+) in four-fold and six-fold coordination is observed in the slowest-quenched samples; Fe(2+) coordination varies directly with quench efficiency. Less pronounced changes were observed in the Ti-rich orange glass. Therefore the remote-sensed spectrum of a glass-bearing regolith on the moon may be influenced by the process by which the glass cooled, and extreme caution must be used when comparing spectra of synthetic glass analogs with real lunar glasses.

  11. 壳牌干煤粉气化技术与壳牌下行水激冷流程气化技术的比较%Comparison of Shell Coal Gasification Technology with Shell Coal Gasification Process Bottom Quench

    Institute of Scientific and Technical Information of China (English)

    胡庆丽; 赖智乐; 王盘峰; 胡步千

    2014-01-01

    Afterwards entering the Chinese market of Shell coal gasification technology, Shell Company has again developed the bottom water quench process gasification technology in order to simplify traditional process, to eliminate stoppage problem of dried ash, and to decrease the investment cost. Author has made comparison for 2 kinds of gasification technologies from aspects of process feature, gasifier structure, equipment arrangement, investment cost and so on, has separately indicated the advantage and shortage between Shell dried and pulverized coal gasification technology and the bottom water quench process gasification technology, result indicates that:①The traditional Shell dried and pulverized coal gasification process technology is ripe and reliable with high heat recovery rate, better economy and environmental protection, but with more investment cost at present stage, more equipment in plant, more difficulty in construction/installation and in piping arrangement;②The structure of gasifier is simple forbottom water quench process gasifica-tion technology newly developed with less equipment in plant, less investment of project, but only one set of plant is now put into operation, so its environ-ment protection property and stability of plant are required to be observed.%继壳牌干煤粉气化技术( SCGP)进入中国市场后,壳牌公司又开发了下行水激冷流程气化技术( SCGP Bot-tom Quench),以简化传统流程,消除干灰堵塞问题,降低投资成本。本文从工艺特点、气化炉结构、设备布置以及投资成本等方面进行了2种气化技术的比较,分别指出了SCGP和SCGP Bottom Quench的优势和劣势,结果表明:①传统的SCGP工艺技术成熟可靠,热回收率高,经济环保,但项目前期投资较大,装置设备较多,施工吊装与管道布置难度较大;②新开发的SCGP Bottom Quench气化炉结构简单,装置设备减少,项目投资缩减,但国内仅有1套装

  12. Time-resolved spectroscopy of the fluorescence quenching of a donor — acceptor pair by halothane

    Science.gov (United States)

    Sharma, A.; Draxler, S.; Lippitsch, M. E.

    1992-04-01

    Donor (anthracene) sensitized acceptor (perylene) fluorescence is quenched more efficiently by halothane than is intrinsic perylene fluorescence. The underlying process of dynamic fluorescence quenching is investigated by time-resolved fluorescence spectroscopy.

  13. A novel method for ranitidine hydrochloride determination in aqueous solution based on fluorescence quenching of functionalised CdS QDs through photoinduced charge transfer process: spectroscopic approach.

    Science.gov (United States)

    Gore, Anil Hanumant; Mote, Umesh Shivaji; Tele, Shahaji Sopan; Anbhule, Prashant Vikramrao; Rath, Madhab Chandra; Patil, Shivajirao Raghunath; Kolekar, Govind Bhagwan

    2011-06-21

    A novel method for the quantitative determination of ranitidine hydrochloride (RNH) based on the fluorescence quenching of functionalised CdS quantum dots (QDs) by RNH in aqueous solution was proposed. The method is simple, rapid, specific and highly sensitive with good precision. The thioglycolic acid (TGA)-capped CdS QDs were synthesized from cadmium nitrate and sodium sulfide in alkaline solution. Under the optimal conditions, the Stern-Volmer calibration plot of F(0)/F against concentration of RNH was linear in the range of 0.50-15.0 μg mL(-1) with a correlation coefficient of 0.996. The limit of detection (LOD) was 0.38 μg mL(-1). The method was satisfactorily applied to the direct determination of RNH in pharmaceutical formulations with no significant interference from excipients. The results were found to be in good agreement with those obtained by the reference method and the claimed value. The accuracy and reliability of the method were further ascertained by recovery studies via the standard-addition method, with percentage recoveries in the range of 98.47 to 102.30%. The possible fluorescence quenching mechanism for the reaction was also discussed.

  14. Photophysical behavior and fluorescence quenching by halides of quinidine dication: Steady state and time resolved study

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Neeraj Kumar; Tewari, Neeraj; Arora, Priyanka; Rautela, Ranjana; Pant, Sanjay [Photophysics Laboratory, Department of Physics, DSB Campus, Kumaun University, Nainital 263002, Uttarakhand (India); Joshi, Hem Chandra, E-mail: hem_sup@yahoo.co.uk [Institute for Plasma Research, Laser Diagnostics Division, Bhat, Near Indira Bridge, Gandhinagar 382428, Gujarat (India)

    2015-02-15

    The fluorescence quenching of quinidine in acidified aqueous solution by various halides (Cl{sup −}, Br{sup −} and I{sup −}) was studied using steady state and time resolved fluorescence techniques. The quenching process was characterized by Stern–Volmer (S–V) plots. Possibility of conformers (one is not quenched by halide and the other is quenched) is invoked to explain the observed results. - Highlights: • Fluorescence quenching of quinidine in acidified aqueous solution by halides. • Various quenching parameters have been estimated. • Possibility of conformers is invoked to explain the observed results.

  15. 高温表面淹没过程中膜态沸腾的实验研究%Experimental Study on Film Boiling of High Temperature Surface During Immersion Quenching Process

    Institute of Scientific and Technical Information of China (English)

    刘斌; 潘良明; 陈德奇; 刘宏波

    2012-01-01

    Film boiling was widely applied in the process of metal heat treatment. The surface temperature and heat transfer coefficient of high temperature surface during immersion quenching process were experimentally studied. During the quenching process, the experimental results reveal that the transfer coefficient goes up to a peak near-lineally and then drops down at the gradually dropping temperature. The results show that the relationship between liquid level increasing speed and transfer coefficient is complicated and is not at a monotonous trend. According to the experimental results, a prediction model about the surface temperature vs time is established, which can predict the surface temperature well.%膜态沸腾在金属热处理等过程中有广泛的应用.本文研究了注水过程中高温表面膜态沸腾表面温度和表面换热系数的变化规律.实验发现:换热系数随表面温度的下降接近直线上升到最大值然后下降,液位上升速度对换热系数的影响较复杂,并不是单调的.根据实验数据,建立了表面温度随时间变化的预测模型,模型能很好地预测表面温度的变化规律.

  16. Superconducting properties of internally stabilized Nb{sub 3}Al wires fabricated by rapid-quenched and transformed process; Naibu anteika kyunetsu kyurei{center_dot}hentai ho Nb{sub 3}Al senzai no chodendo tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Tagawa, K. [Hitachi Cable, Ltd., Tokyo (Japan); National Research Institute for Metals, Tokyo (Japan); Japan Science and Technology Corp., Saitama (Japan); Nakagawa, K. [Hitachi Cable, Ltd., Tokyo (Japan); Takeuchi, T.; Banno, N.; Kiyoshi, T.; Ito, K.; Wada, H. [National Research Institute for Metals, Tokyo (Japan); Yuyama, M.; Kosuge, M. [National Research Institute for Metals, Tokyo (Japan)

    2000-05-29

    Nb{sub 3}AL wire using Ag coated by Nb as stabilizer was manufactured as trial and the critical current density Jc was examined. Compared Ag with Nb as fill-in core bar, Jc of wire using silver filament core bar was higher than one using Nb filament core. It was considered that uniform current in Ag caused to produce homogeneous solid solution. Jc also increased by about 45% following processing of decreasing area after rapid heating and quench. N value also showed at least a value above and equal to 25 at the 21 T magnetic field. (NEDO)Nb{sub 3}AL wire using Ag coated by Nb as stabilizer was manufactured as trial and the critical current density Jc was examined. Compared Ag with Nb as fill-in core bar, Jc of wire using silver filament core bar was higher than one using Nb filament core. It was considered that uniform current in Ag caused to produce homogeneous solid solution. Jc also increased by about 45% following processing of decreasing area after rapid heating and quench. N value also showed at least a value above and equal to 25 at the 21 T magnetic field. (NEDO)

  17. Design and Implementation of Quench Protection in the EAST Cryogenic Control System

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhiwei; BAI Hongyu; ZHUANG Ming; HU Liangbing; XIA Genhai

    2009-01-01

    An outline of the complete design of the cryogenic system, including the detection of quench signals, the processing flow after a quench and the concrete measures of pressure release for EAST is described in this paper. The hardware and software configurations on DeltaV DCS are illustrated in detail. The results of quench protection testing in cooling experiments are also analyzed.

  18. LHC BFPP Quench Test with Ions (2015)

    CERN Document Server

    Schaumann, Michaela; Bahamonde Castro, Cristina; Auchmann, Bernhard; Chetvertkova, Vera; Giachino, Rossano; Jowett, John; Kalliokoski, Matti; Lechner, Anton; Mertens, Tom; Ponce, Laurette; CERN. Geneva. ATS Department

    2016-01-01

    The 2015 Pb-Pb collision run of the LHC operated at a beam energy of 6.37Z TeV. The power of the secondary beams emitted from the interaction point by the bound-free pair production (BFPP) process reached new levels while the propensity of the bending magnets to quench is higher at the new magnetic field levels. This beam power is about 70 times greater than that contained in the luminosity debris and is focussed on a specific location. As long foreseen, orbit bumps were introduced in the dispersion suppressors around the highest luminosity experiments to mitigate the risk of quenches by displacing and spreading out these losses. Because the impact position and intensity of these secondary beams is well known and can be tracked easily with the Beam Loss Monitors (BLMs), the BFPP1 beam (208Pb81+ ions), which is the most intense, provides a tool to accurately measure the steady state quench limit of the LHC main dipoles. At the moment the exact quench limit is not known, but this knowledge is important to asses...

  19. Evidence for an unidentified non-photochemical ground-level source of formaldehyde in the Po Valley with potential implications for ozone production

    NARCIS (Netherlands)

    Kaiser, J.; Wolfe, G.M.; Bohn, B.; Ganzeveld, L.N.

    2015-01-01

    Ozone concentrations in the Po Valley of northern Italy often exceed international regulations. As both a source of radicals and an intermediate in the oxidation of most volatile organic compounds (VOCs), formaldehyde (HCHO) is a useful tracer for the oxidative processing of hydrocarbons that leads

  20. Holographic Quenches with a Gap

    CERN Document Server

    da Silva, Emilia; Mas, Javier; Serantes, Alexandre

    2016-01-01

    In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.

  1. Holographic quenches with a gap

    Science.gov (United States)

    da Silva, Emilia; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2016-06-01

    In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.

  2. STUDY ON POTASSIUM COMPOSITION AND MORPHOLOGICAL TRANSFOMATION FACTORS DURING ROASTING AND QUENCHING PROCESS%焙烧与急冷过程中钾元素组成及其形态转变因素探析

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    On the basis of analyzing potassium resource in molybdenum products ,and in accordance with the roast-ing production practice of the molybdenum concentrate in the multiple hearth furnace , it is mainly expounded that the multiple hearth furnace roasting and quenching process are the mainly factors to influence the composition of po-tassium and its morphology change in the high soluble roasted molybdenum concentrates. And it is also put forward that the composition of the potassium and ways of its morphology change in high dissolved roasted molybdenum con-centrate are controlled by the roasting condition of the multiple hearth furnace and quenching process, by which the high dissolved roasted molybdenum concentrate products can meet the subsequent quality requirements for low po-tassium molybdenum chemicals.%本文根据钼产品钾来源分析情况,结合多膛炉焙烧钼精矿生产实际,阐述了多膛炉焙烧与急冷生产过程是影响高溶焙烧钼精矿中钾元素组成及其形态转变的主要因素,同时提出了多膛炉焙烧及急冷工艺控制高溶焙烧钼精矿中钾元素组成及其形态转变途径,使高溶焙烧钼精矿产品满足后续钼化工对低钾原料的质量要求。

  3. Plasma quench production of titanium from titanium tetrachloride

    Energy Technology Data Exchange (ETDEWEB)

    Sears, J.W.

    1994-10-01

    This project, Plasma Quench Production of Titanium from Titanium Tetrachloride, centers on developing a technique for rapidly quenching the high temperature metal species and preventing back reactions with the halide. The quenching technique chosen uses the temperature drop produced in a converging/diverging supersonic nozzle. The rapid quench provided by this nozzle prevents the back reaction of the halide and metal. The nature of the process produces nanosized particles (10 to 100 nm). The powders are collected by cyclone separators, the hydrogen flared, and the acid scrubbed. Aluminum and titanium powders have been produced in the laboratory-scale device at 1 gram per hour. Efforts to date to scale up this process have not been successful.

  4. Jet quenching from QCD evolution

    Science.gov (United States)

    Chien, Yang-Ting; Emerman, Alexander; Kang, Zhong-Bo; Ovanesyan, Grigory; Vitev, Ivan

    2016-04-01

    Recent advances in soft-collinear effective theory with Glauber gluons have led to the development of a new method that gives a unified description of inclusive hadron production in reactions with nucleons and heavy nuclei. We show how this approach, based on the generalization of the DGLAP evolution equations to include final-state medium-induced parton shower corrections for large Q2 processes, can be combined with initial-state effects for applications to jet quenching phenomenology. We demonstrate that the traditional parton energy loss calculations can be regarded as a special soft-gluon emission limit of the general QCD evolution framework. We present phenomenological comparison of the SCETG -based results on the suppression of inclusive charged hadron and neutral pion production in √{sNN }=2.76 TeV lead-lead collisions at the Large Hadron Collider to experimental data. We also show theoretical predictions for the upcoming √{sNN }≃5.1 TeV Pb +Pb run at the LHC.

  5. Quench simulations for superconducting elements in the LHC accelerator

    CERN Document Server

    Sonnemann, F

    2000-01-01

    The design of he protection system for he superconducting elements in an accel- erator such as the Large Hadron Collider (LHC),now under construction at CERN, requires a detailed understanding of the hermo-hydraulic and electrodynamic pro- cesses during a quench.A numerical program (SPQR -Simulation Program for Quench Research)has been developed o evaluate temperature and voltage dis ri- butions during a quench as a func ion of space and ime.The quench process is simulated by approximating the heat balance equation with the finite di fference method in presence of variable cooling and powering conditions.The simulation predicts quench propagation along a superconducting cable,forced quenching with heaters,impact of eddy curren s induced by a magnetic field change,and heat trans- fer hrough an insulation layer in o helium,an adjacen conductor or other material. The simulation studies allowed a better understanding of experimental quench data and were used for determining the adequ...

  6. Quench dynamics in silver coated YBCO tapes

    Science.gov (United States)

    Duckworth, R. C.; Pfotenhauer, J. M.; Lue, J. W.; Gouge, M. J.; Lee, D. F.; Kroeger, D. M.

    2002-05-01

    The role of silver in the quench dynamics of RABiTS-processed YBCO tapes was examined. The voltage distribution along the 20 cm long YBCO tapes with silver thickness between two and eight micrometers was measured when different transport current pulses were applied. Measurements on each sample were performed in a conduction-cooling environment at approximately 50 K. After normal regions were induced in the sample by short over-current pulses, an operating current was applied to monitor the sample recovery or quench. When scaled to the lowest critical current, a thermal runaway current was identified and found to increase with increasing silver thickness. A simple one-dimensional model of the system supported this trend. [This paper is also published in Advances in Cryogenic Engineering Volume 47A, AIP Conference Proceedings Volume 613, pp. 449-456.

  7. Quench Tests of LHC Magnets with Beam: Studies on Beam Loss development and determination of Quench levels

    CERN Document Server

    Priebe, A; Sapinski, M

    The application of superconducting materials in the field of high energy accelerator physics not only opens the doors to the generation of the magnetic fields unattainable to normal conductors but also demands facing new challenges. A transition fromthe superconducting state, which is characterized by a resistance-free flow of the electric current, to the normal conducting state is called quenching. This process might be extremely dangerous and even lead to destruction of amagnet superconducting coil if no protecting actions are taken. Therefore, the knowledge of a magnet quench level, i.e. amount of energy which causes the transition to the resistive state, is crucial for the safety and operational efficiency of the accelerator. Regarding that, specific thresholds are incorporated to dedicated quench prevention systems in order to suppress the origin of detected energy perturbation, for example beam losses, or mitigate the consequences of the quenching process by dissipating the energy stored in the magnetic...

  8. Quenching and tempering process of 20CrMo steel hollow sucker rod%20 CrMo钢空心抽油杆的调质处理工艺

    Institute of Scientific and Technical Information of China (English)

    范世平; 李小彦; 郭纯恩

    2015-01-01

    研究20CrMo钢空心抽油杆经过不同调质处理后的显微组织、力学性能。结果表明,20CrMo钢经880℃淬火+580℃回火处理后组织构成理想,无影响材料塑韧性的不利组织,晶粒细小;在获得高强度的同时,强度和塑韧性有良好配合,抗拉强度达到998 MPa,屈服强度856 MPa,伸长率20%,断面收缩率56%,冲击吸收能量24 kJ,大大减少了作业过程中空心抽油杆井下疲劳断裂次数。%Microstructure and mechanical properties of 20CrMo steel hollow sucker rod after different quenching and tempering were studied . The results show that 20CrMo steel after 880℃quenching+580℃tempering,the constitution of microstructure is ideal , without unfavourable impact on toughness and plastic , the grain size is fine;at the same time of achieving high strength ,the strength and plastic toughness gets good match,the tensile strength is 998 MPa,the yield strength is 856 MPa,the elongation is 20%,the reduction of area is 56%,the impact absorbed energy is 24 kJ,thus greatly reduces the number of hollow sucker rod's fatigue fracture during downhole operation process .

  9. Universality in fast quantum quenches

    CERN Document Server

    Das, Sumit R; Myers, Robert C

    2014-01-01

    We expand on the investigation of the universal scaling properties in the early time behaviour of fast but smooth quantum quenches in a general $d$-dimensional conformal field theory deformed by a relevant operator of dimension $\\Delta$ with a time-dependent coupling. The quench consists of changing the coupling from an initial constant value $\\lambda_1$ by an amount of the order of $\\delta \\lambda$ to some other final value $\\lambda_2$, over a time scale $\\delta t$. In the fast quench limit where $\\delta t$ is smaller than all other length scales in the problem, $ \\delta t \\ll \\lambda_1^{1/(\\Delta-d)}, \\lambda_2^{1/(\\Delta-d)}, \\delta \\lambda^{1/(\\Delta-d)}$, the energy (density) injected into the system scales as $\\delta{\\cal E} \\sim (\\delta \\lambda)^2 (\\delta t)^{d-2\\Delta}$. Similarly, the change in the expectation value of the quenched operator at times earlier than the endpoint of the quench scales as $\\langle {\\cal O}_\\Delta\\rangle \\sim \\delta \\lambda\\, (\\delta t)^{d-2\\Delta}$, with further logarithmic...

  10. Chiral Logs in Quenched QCD

    CERN Document Server

    Dong, S J; Horváth, I; Lee, F X; Liu, K F; Mathur, N; Zhang, J B

    2003-01-01

    The quenched chiral logs are examined on a $16^3 \\times 28$ lattice with Iwasaki gauge action and overlap fermions. The pion decay constant $f_{\\pi}$ is used to set the lattice spacing, $a = 0.200(3)$ fm. With pion mass as low as $\\sim 180 {\\rm MeV}$, we see the quenched chiral logs clearly in $m_{\\pi}^2/m$ and $f_P$, the pseudoscalar decay constant. We analyze the data to determine how low the pion mass needs to be in order for the quenched one-loop chiral perturbation theory ($\\chi$PT) to apply. With the constrained curve fitting, we are able to extract the quenched chiral log parameter $\\delta$ together with the chiral cutoff $\\Lambda_{\\chi}$ and other parameters. Only for $m_{\\pi} \\leq 300 {\\rm MeV}$ do we obtain a consistent and stable fit with a constant $\\delta$ which we determine to be 0.23(2). By comparing to the $12^3 \\times 28$ lattice, we estimate the finite volume effect to be about 1.8% for the smallest pion mass. We also study the quenched non-analytic terms in the nucleon and the $\\rho$ masses...

  11. Vertical observation of molecular hydrogen and carbon monoxide: Implication for non-photochemical H2 production at ocean surface and subsurface

    Science.gov (United States)

    Kawagucci, S.; Narita, T.; Obata, H.; Ogawa, H.; Gamo, T.

    2009-12-01

    concentration were observed. Apparently different vertical distributions between H2 and CO concentration were revealed at all the observed stations. At a station where N-nutrient was depleted through surface mixed layer, H2 was supersaturated at the surface while CO concentration was constant through the depths. In contrast, at another station where some amount of terrestrial humic matter was introduced into the surface, H2 concentration was constantly undersaturated through the depth while vertical distribution of CO concentration showed the highest at the surface and exponentially decreased to deep. These facts suggest that H2 production involved with nitrogen fixation played an important role for H2 behavior in ocean water while photochemical H2 production would be a minor process. In addition to the surface, H2 supersaturation accoumpanied with little CO concentration rise were observed at depths just below the mixed layer in pycnocline with Chlorophyll maximum.

  12. Spontaneous quenches of a high temperature superconducting pancake coil

    Energy Technology Data Exchange (ETDEWEB)

    Lue, J.W.; Lubell, M.S. [Oak Ridge National Lab., TN (United States); Aized, D.; Campbell, J.M.; Schwall, R.E. [American Superconductor Corp., Westborough, MA (United States)

    1995-09-01

    A double-pancake coil made of Bi-2223/Ag high temperature superconducting (HTS) tape was constructed with an embedded heater and graded conductors to study the stability and quench propagation in HTS coils. The experiments were performed with liquid nitrogen and gaseous helium cooling in temperatures ranging from 5 to 77 K. The coil was very stable, and no ``normal`` zone was sustained or propagated with local pulsed heating. However, spontaneous quenches of the cod were experienced. This was found to be the result of having the coil current higher than that of the lower I{sub c} sections of the coil for a long time. This quench process took minutes to develop--much longer than would be expected in a low temperature superconducting coil. The quench behaved more like a spreading and continuous heating of an increasingly larger partially resistive section of the coil than like a sequential ``normal`` front propagation.

  13. Quenching effects in Cu-Al-Mn shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Obrado, E.; Manosa, L.; Planes, A. [Barcelona Univ. (Spain). Dept. d' Estructura i Constituents de la Materia; Romero, R.; Somoza, A. [IFIMAT, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil, and Comision de Investigaciones Cientificas de la Provincia de Buenos Aires, Buenos Aires (Argentina)

    1999-12-15

    In this paper the effect of quenching from different temperatures (T{sub q}) in a Cu-Al-Mn alloy is studied. This alloy system, which displays an L2{sub 1} ordered structure, transforms martensitically at an intermediate temperature T{sub M}, and undergoes a spin freezing process at a lower temperature T{sub f}. Positron annihilation measurements have shown that after the quench, an excess of vacancies is retained in the system, depending on T{sub q}. In addition, both T{sub M} and T{sub f} have been found to be sensitive to T{sub q}. This has been attributed to frozen-in disorder induced by the quench. Experimental results have been interpreted in terms of the growth of magnetic clusters, quenched-in vacancies and atomic disorder. (orig.)

  14. Simulating Zeno physics by a quantum quench with superconducting circuits

    Science.gov (United States)

    Tong, Qing-Jun; An, Jun-Hong; Kwek, L. C.; Luo, Hong-Gang; Oh, C. H.

    2014-06-01

    Studying out-of-equilibrium physics in quantum systems under quantum quench is of vast experimental and theoretical interest. Using periodic quantum quenches, we present an experimentally accessible scheme to simulate the quantum Zeno and anti-Zeno effects in an open quantum system of a single superconducting qubit interacting with an array of transmission line resonators. The scheme is based on the following two observations: First, compared with conventional systems, the short-time nonexponential decay in our superconducting circuit system is readily observed; and second, a quench-off process mimics an ideal projective measurement when its time duration is sufficiently long. Our results show the active role of quantum quench in quantum simulation and control.

  15. Quench dynamics in SRF cavities: can we locate the quench origin with 2nd sound?

    Energy Technology Data Exchange (ETDEWEB)

    Maximenko, Yulia; /Moscow, MIPT; Segatskov, Dmitri A.; /Fermilab

    2011-03-01

    A newly developed method of locating quenches in SRF cavities by detecting second-sound waves has been gaining popularity in SRF laboratories. The technique is based on measurements of time delays between the quench as determined by the RF system and arrival of the second-sound wave to the multiple detectors placed around the cavity in superfluid helium. Unlike multi-channel temperature mapping, this approach requires only a few sensors and simple readout electronics; it can be used with SRF cavities of almost arbitrary shape. One of its drawbacks is that being an indirect method it requires one to solve an inverse problem to find the location of a quench. We tried to solve this inverse problem by using a parametric forward model. By analyzing the data we found that the approximation where the second-sound emitter is a near-singular source does not describe the physical system well enough. A time-dependent analysis of the quench process can help us to put forward a more adequate model. We present here our current algorithm to solve the inverse problem and discuss the experimental results.

  16. Quenching in coupled adiabatic coils

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.E.C.

    1985-03-01

    The prediction of the effects of a quench on stress and temperature is an important aspect of the design of superconducting magnets. Of particular interest, and the exclusive topic of this study, is the prediction of the effects of quenching in coupled adiabatic coils, such as the multi-section windings of a high field NMR spectrometer magnet. The predictive methods used here are based on the measurement of the time of propagation of quench between turns. From this measurement an approximate algorithum for the propagation time is used in a code which solves the linear differential equations for the coil currents and calculates the movement of normal zone boundaries and hence the associated winding resistance.

  17. Precise gas carburizing quenching process of 18 Cr2 Ni4 WA steel bushes%18Cr2Ni4WA钢衬套的精密气体渗碳淬火热处理

    Institute of Scientific and Technical Information of China (English)

    李锋; 王新宇; 李世键; 韩培培; 于浩

    2016-01-01

    The influence of precise gas carburizing and isothermal quenching process on carburized layer hardness , depth and the microstructure of 18Cr2Ni4WA steel was studied .The results show that the carburized layer depth increases with the increasing of the total holding time, but the hardness profile becomes flat gradually .The longer of strong carburizing time , the deeper of carburized depth with the same total holding time .The longer of strong carburizing time , the lower of surface hardness with the same diffusion carburizing time .The optimized precise heat treatment process consists of holding temperature at 910 ℃, by carbon potential of strong carburizing stage at 1.20%and holding for 3 h, and then by carbon potential of diffusion stage at 0.80%and holding for 1 h,and then isothermally quenched in nitrate bath.With this optimized process , the typical carburized depth of (1.2 ±0.1) mm with favorable microstructure distribution is obtained . The process has been successfully applied in bushes production with satisfactory requirement of carburized depth , hardness profile and microstructure .%研究了精密气体渗碳等温淬火工艺对18Cr2Ni4WA钢渗层硬度、深度及显微组织的影响。结果表明,随着总渗碳保温时间的延长,渗层深度增加,但硬度曲线变得平缓;在相同总保温时间的情况下,强渗时间越长,渗层越深;而当扩散时间相同时,强渗时间越长,淬火后表层的硬度较低。优化的精密气体渗碳工艺为:保温温度均为910℃,强渗阶段碳势1.20%,保温3 h;扩散阶段碳势0.80%,保温1 h,渗碳后进行等温淬火,可以获得(1.2±0.1) mm渗层深度。渗碳淬火后渗层组织良好。该工艺成功应用于衬套零件的实际生产,满足了设计要求。

  18. Bioanalytical Applications of Fluorenscence Quenching.

    Science.gov (United States)

    1986-02-10

    interaction of different cyclodextrin systems with the polynuclear aromatic compound, pyrene.(7 ) There are other cases where the Stern-Volmer plot deviates... encapsulated in lecithin liposomes. In this manner the fluorescence is self-quenched. When the liposomes are disrupted, the dye is released and

  19. NASA MSFC Electrostatic Levitator (ESL) Rapid Quench System

    Science.gov (United States)

    SanSoucie, Michael P.; Craven, Paul D.

    2014-01-01

    Electrostatic levitation, a form of containerless processing, is an important tool in materials research. Levitated specimens are free from contact with a container; therefore, heterogeneous nucleation on container walls is not possible. This allows studies of deeply undercooled melts. Furthermore, studies of high-temperature, highly reactive materials are also possible. Studies of the solidification and crystallization of undercooled melts is vital to the understanding of microstructure development, particularly the formation of alloys with unique properties by rapid solidification. The NASA Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) lab has recently been upgraded to allow for rapid quenching of levitated materials. The ESL Rapid Quench System uses a small crucible-like vessel that can be partially filled with a low melting point material, such as a Gallium alloy, as a quench medium. An undercooled sample can be dropped into the vessel to rapidly quench the sample. A carousel with nine vessels sits below the bottom electrode assembly. This system allows up to nine rapid quenches before having to break vacuum and remove the vessels. This new Rapid Quench System will allow materials science studies of undercooled materials and new materials development. In this presentation, the system is described and initial results are presented.

  20. How to quench a galaxy

    Science.gov (United States)

    Pontzen, Andrew; Tremmel, Michael; Roth, Nina; Peiris, Hiranya V.; Saintonge, Amélie; Volonteri, Marta; Quinn, Tom; Governato, Fabio

    2017-02-01

    We show how the interplay between active galactic nuclei (AGNs) and merger history determines whether a galaxy quenches star formation (SF) at high redshift. We first simulate, in a full cosmological context, a galaxy of total dynamical mass Mvir = 1012 M⊙ at z = 2. Then we systematically alter the accretion history of the galaxy by minimally changing the linear overdensity in the initial conditions. This `genetic modification' approach allows the generation of three sets of Λ CDM initial conditions leading to maximum merger ratios of 1:10, 1:5 and 2:3, respectively. The changes leave the final halo mass, large-scale structure and local environment unchanged, providing a controlled numerical experiment. Interaction between the AGN physics and mergers in the three cases leads, respectively, to a star-forming, temporarily quenched and permanently quenched galaxy. However, the differences do not primarily lie in the black hole accretion rates, but in the kinetic effects of the merger: the galaxy is resilient against AGN feedback unless its gaseous disc is first disrupted. Typical accretion rates are comparable in the three cases, falling below 0.1 M⊙ yr-1, equivalent to around 2 per cent of the Eddington rate or 10-3 times the pre-quenching star formation rate, in agreement with observations. This low level of black hole accretion can be sustained even when there is insufficient dense cold gas for SF. Conversely, supernova feedback is too distributed to generate outflows in high-mass systems, and cannot maintain quenching over periods longer than the halo gas cooling time.

  1. Explaining jet quenching with perturbative QCD alone

    CERN Document Server

    Zapp, Korinna C; Wiedemann, Urs A

    2011-01-01

    We present a new formulation of jet quenching in perturbative QCD beyond the eikonal approximation. Multiple scattering in the medium is modelled through infra-red-continued (2 -> 2) scattering matrix elements in QCD and the parton shower describing further emissions. The interplay between these processes is arranged in terms of a formation time constraint such that coherent emissions can be treated consistently. Emerging partons are hadronised by the Lund string model, tuned to describe LEP data in conjunction with the parton shower. Based on this picture we obtain a good description of the nuclear modification factor R_AA at RHIC and LHC.

  2. Quench modeling of the ATLAS superconducting toroids

    CERN Document Server

    Gavrilin, A V; ten Kate, H H J

    2001-01-01

    Details of the normal zone propagation and the temperature distribution in the coils of ATLAS toroids under quench are presented. A tailor-made mathematical model and corresponding computer code enable obtainment of computational results for the propagation process over the coils in transverse (turn-to-turn) and longitudinal directions. The slow electromagnetic diffusion into the pure aluminum stabilizer of the toroid's conductor, as well as the essentially transient heat transfer through inter-turn insulation, is appropriately included in the model. The effect of nonuniform distribution of the magnetic field and the thermal links to the coil casing on the temperature gradients within the coils is analyzed in full. (5 refs).

  3. Neutron diffraction study of the Sr 1-xBi xF 2+x solid solution quenched from 700°C : Proposition of a clustering process

    Science.gov (United States)

    Soubeyroux, J. L.; Réau, J. M.; Wahbi, M.; Sénégas, J.; Soo, Suh Kyung

    1992-07-01

    A neutron diffraction investigation of the fluorite-type Sr 1-xBi xF 2+x (0 ⩽ x ≲ 0.50) solid solution has revealed the existence of three F' F″ and F'″ interstitial flouride ions. The anionic distribution between normal and interstitial sites has been determined as a function of x. A clustering process has been proposed in Sr 1-xBi xF 2+x on the basis of neutron diffraction results and of the composition dependence of electrical properties. It consists in a progressive transformation with increasing x of 3:2:3:0 clusters into "1:0:3:0" clusters.

  4. Photoprotection in higher plants: the putative quenching site is conserved in all outer light-harvesting complexes of Photosystem II.

    Science.gov (United States)

    Mozzo, Milena; Passarini, Francesca; Bassi, Roberto; van Amerongen, Herbert; Croce, Roberta

    2008-10-01

    In bright sunlight, the amount of energy harvested by plants exceeds the electron transport capacity of Photosystem II in the chloroplasts. The excess energy can lead to severe damage of the photosynthetic apparatus and to avoid this, part of the energy is thermally dissipated via a mechanism called non-photochemical quenching (NPQ). It has been found that LHCII, the major antenna complex of Photosystem II, is involved in this mechanism and it was proposed that its quenching site is formed by the cluster of strongly interacting pigments: chlorophylls 611 and 612 and lutein 620 [A.V. Ruban, R. Berera, C. Ilioaia, I.H.M. van Stokkum, J.T.M. Kennis, A.A. Pascal, H. van Amerongen, B. Robert, P. Horton and R. van Grondelle, Identification of a mechanism of photoprotective energy dissipation in higher plants, Nature 450 (2007) 575-578.]. In the present work we have investigated the interactions between the pigments in this cluster not only for LHCII, but also for the homologous minor antenna complexes CP24, CP26 and CP29. Use was made of wild-type and mutated reconstituted complexes that were analyzed with (low-temperature) absorption and circular-dichroism spectroscopy as well as by biochemical methods. The pigments show strong interactions that lead to highly specific spectroscopic properties that appear to be identical for LHCII, CP26 and CP29. The interactions are similar but not identical for CP24. It is concluded that if the 611/612/620 domain is responsible for the quenching in LHCII, then all these antenna complexes are prepared to act as a quencher. This can explain the finding that none of the Lhcb complexes seems to be strictly required for NPQ while, in the absence of all of them, NPQ is abolished.

  5. Quenched Reinforcement Exposed to Fire

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    2006-01-01

    Idealized data are derived for the tensile strength of quenched and tempered prestressing steel and of quenched and self-tempered reinforcing bars for fire safety design. 0.2% stresses are derived as a function of the maximum temperature and in addition, 2.0% stresses are provided. A strain of 2.......0% is seldom found in “slack” (not prestressed) reinforcement, but 2.0% stresses might be relevant for reinforcement in T shaped cross sections and for prestressed structures, where large strains can be applied. All data are provided in a “HOT” condition during a fire and in a “COLD” condition after a fire....... The COLD condition is relevant for analyses of residual load bearing capacity of a structure after a fire exposure. It is also relevant for analyses of concrete structures exposed to fully developed fire courses. The reason is that compression zones of concrete are always the weakest in the cooling phase...

  6. Holographic quenches and anomalous transport

    CERN Document Server

    Ammon, Martin; Jimenez-Alba, Amadeo; Macedo, Rodrigo P; Melgar, Luis

    2016-01-01

    We study the response of the chiral magnetic effect due to continuous quenches induced by time dependent electric fields within holography. Concretely, we consider a holographic model with dual chiral anomaly and compute the electric current parallel to a constant, homogeneous magnetic field and a time dependent electric field in the probe approximation. We explicitly solve the PDEs by means of pseudospectral methods in spatial and time directions and study the transition to an universal "fast" quench response. Moreover, we compute the amplitudes, i.e.,~residues of the quasi normal modes, by solving the (ODE) Laplace transformed equations. We investigate the possibility of considering the asymptotic growth rate of the amplitudes as a well defined notion of initial time scale for linearized systems. Finally, we highlight the existence of Landau level resonances in the electrical conductivity parallel to a magnetic field at finite frequency and show explicitly that these only appear in presence of the anomaly. ...

  7. Quench cooling under reduced gravity

    CERN Document Server

    Chatain, D; Nikolayev, V S; Beysens, D

    2013-01-01

    We report the quench cooling experiments performed with liquid O2 under different levels of gravity simulated with the magnetic gravity compensation. A copper disk is quenched from 270K to 90K. It is found that the cooling time in microgravity is very long in comparison with any other gravity level. This phenomenon is explained by the isolation effect of the gas surrounding the disk. The liquid subcooling is shown to drastically improuve the heat exchange thus reducing the cooling time (about 20 times). The effect of subcooling on the heat transfer is analyzed at different gravity levels. It is shown that such type of experiments cannot be used for the analysis of the critical heat flux (CHF) of the boiling crisis. The minimum heat flux (MHF) of boiling is analyzed instead.

  8. Quenched Reinforcement Exposed to Fire

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    2006-01-01

    Idealized data are derived for the tensile strength of quenched and tempered prestressing steel and of quenched and self-tempered reinforcing bars for fire safety design. 0.2% stresses are derived as a function of the maximum temperature and in addition, 2.0% stresses are provided. A strain of 2.......0% is seldom found in “slack” (not prestressed) reinforcement, but 2.0% stresses might be relevant for reinforcement in T shaped cross sections and for prestressed structures, where large strains can be applied. All data are provided in a “HOT” condition during a fire and in a “COLD” condition after a fire....... The COLD condition is relevant for analyses of residual load bearing capacity of a structure after a fire exposure. It is also relevant for analyses of concrete structures exposed to fully developed fire courses. The reason is that compression zones of concrete are always the weakest in the cooling phase...

  9. TASK 2: QUENCH ZONE SIMULATION

    Energy Technology Data Exchange (ETDEWEB)

    Fusselman, Steve

    2015-09-30

    Aerojet Rocketdyne (AR) has developed an innovative gasifier concept incorporating advanced technologies in ultra-dense phase dry feed system, rapid mix injector, and advanced component cooling to significantly improve gasifier performance, life, and cost compared to commercially available state-of-the-art systems. A key feature of the AR gasifier design is the transition from the gasifier outlet into the quench zone, where the raw syngas is cooled to ~ 400°C by injection and vaporization of atomized water. Earlier pilot plant testing revealed a propensity for the original gasifier outlet design to accumulate slag in the outlet, leading to erratic syngas flow from the outlet. Subsequent design modifications successfully resolved this issue in the pilot plant gasifier. In order to gain greater insight into the physical phenomena occurring within this zone, AR developed a cold flow simulation apparatus with Coanda Research & Development with a high degree of similitude to hot fire conditions with the pilot scale gasifier design, and capable of accommodating a scaled-down quench zone for a demonstration-scale gasifier. The objective of this task was to validate similitude of the cold flow simulation model by comparison of pilot-scale outlet design performance, and to assess demonstration scale gasifier design feasibility from testing of a scaled-down outlet design. Test results did exhibit a strong correspondence with the two pilot scale outlet designs, indicating credible similitude for the cold flow simulation device. Testing of the scaled-down outlet revealed important considerations in the design and operation of the demonstration scale gasifier, in particular pertaining to the relative momentum between the downcoming raw syngas and the sprayed quench water and associated impacts on flow patterns within the quench zone. This report describes key findings from the test program, including assessment of pilot plant configuration simulations relative to actual

  10. Jet-quenching and correlations

    Indian Academy of Sciences (India)

    Fuqiang Wang

    2015-05-01

    This article reviews recent advances in our understanding of the experimental aspects of jet-quenching and correlations in relativistic heavy-ion collisions at RHIC and LHC. Emphasis is put on correlation measurements, namely jet-like correlations with anisotropic flow subtraction in heavy-ion collisions and long-range pseudorapidity correlations in small systems. Future path on correlation studies is envisioned which may elucidate jet–medium interactions and the properties of the hot dense medium in QCD.

  11. The LHC quench protection system

    CERN Multimedia

    2009-01-01

    The new quench protection system (QPS) has the crucial roles of providing an early warning for any part of the superconducting coils and busbars that develop high resistance, as well as triggering the switch-off of the machine. Over 2000 new detectors will be installed around the LHC to make sure every busbar segment between magnets is monitored and protected. One of the major consolidation activities for the LHC is the addition of two new detectors to the quench protection system. A magnet quench occurs when part of the superconducting cable becomes normally-conducting. When the protection system detects an increased resistance the huge amount of energy stored in the magnet chains is safely extracted and ‘dumped’ into specially designed resistors. In the case of the main dipole chain, the stored energy in a single LHC sector is roughly the same as the kinetic energy of a passenger jet at cruising speed. The first new detector is designed to monitor the superconducting...

  12. How to quench a galaxy

    CERN Document Server

    Pontzen, Andrew; Roth, Nina; Peiris, Hiranya V; Saintonge, Amélie; Volonteri, Marta; Quinn, Tom; Governato, Fabio

    2016-01-01

    We show how the interplay between active galactic nuclei (AGN) and merger history determines whether a galaxy quenches star formation at high redshift. We first simulate, in a full cosmological context, a galaxy of total dynamical mass $10^{12}\\,M_{\\odot}$ at $z=2$. Then we systematically alter the accretion history of the galaxy by minimally changing the linear overdensity in the initial conditions. This "genetic modification" approach allows the generation of three sets of $\\Lambda$CDM initial conditions leading to maximum merger ratios of 1:10, 1:5 and 2:3 respectively. The changes leave the final halo mass, large scale structure and local environment unchanged, providing a controlled numerical experiment. Interaction between the AGN physics and mergers in the three cases lead respectively to a star-forming, temporarily-quenched and permanently-quenched galaxy. However the differences do not primarily lie in the black hole accretion rates, but in the kinetic effects of the merger: the galaxy is resilient a...

  13. Overconsumption, outflows and the quenching of satellite galaxies

    CERN Document Server

    McGee, Sean L; Balogh, Michael L

    2014-01-01

    The baryon cycle of galaxies is a dynamic process involving the intake, consumption and ejection of vast quantities of gas. In contrast, the conventional picture of satellite galaxies has them methodically turning a large gas reservoir into stars until this reservoir is forcibly removed due to external ram pressure. This picture needs revision. Our modern understanding of the baryon cycle suggests that in some regimes the simple interruption of the fresh gas supply may quench satellite galaxies long before stripping events occur, a process we call overconsumption. We compile measurements from the literature of observed satellite quenching times at a range of redshifts to determine if satellites are principally quenched through orbit-based gas stripping events -- either direct stripping of the disk (ram pressure stripping) or the extended gas halo (strangulation) -- or from internally-driven star formation outflows via overconsumption. The observed timescales show significant deviation from the evolution expec...

  14. How Cosmic Web Detachment Drives Galaxy Quenching

    CERN Document Server

    Aragon-Calvo, Miguel A; Silk, Joseph

    2016-01-01

    We present the Cosmic Web Detachment (CWD) model, a conceptual framework to interpret galaxy evolution in a cosmological context, providing a direct link between the star formation history of galaxies and the cosmic web. The CWD model unifies several mechanism known to disrupt or stop star formation into one single physical process and provides a natural explanation for a wide range of galaxy properties. Galaxies begin accreting star-forming gas at early times via a network of primordial highly coherent filaments. The efficient star formation phase ends when non-linear interactions with other galaxies or elements of the cosmic web detach the galaxy from its network of primordial filaments, thus ending the efficient accretion of cold gas. The stripping of the filamentary web around galaxies is the physical process responsible of star formation quenching in gas stripping, harassment, strangulation and starvation. Being a purely gravitational/mechanical process CWD acts at a more fundamental level than internal ...

  15. Quantum quench and scaling of entanglement entropy

    Science.gov (United States)

    Caputa, Paweł; Das, Sumit R.; Nozaki, Masahiro; Tomiya, Akio

    2017-09-01

    Global quantum quench with a finite quench rate which crosses critical points is known to lead to universal scaling of correlation functions as functions of the quench rate. In this work, we explore scaling properties of the entanglement entropy of a subsystem in a harmonic chain during a mass quench which asymptotes to finite constant values at early and late times and for which the dynamics is exactly solvable. When the initial state is the ground state, we find that for large enough subsystem sizes the entanglement entropy becomes independent of size. This is consistent with Kibble-Zurek scaling for slow quenches, and with recently discussed ;fast quench scaling; for quenches fast compared to physical scales, but slow compared to UV cutoff scales.

  16. The Effect of the Quenching Method on the Deformations Size of Gear Wheels after Vacuum Carburizing

    Directory of Open Access Journals (Sweden)

    Dybowski K.

    2016-06-01

    Full Text Available This paper presents a comparison of the deformations and residual stresses in gear wheels after vacuum carburizing process with quenching in high-pressure nitrogen and oil. The comparison was made on a medium-sized gear wheels, made of AMS6265 (AISI 9310 steel. This steel is applied in the aerospace industry for gears. The study has provided grounds for an assessment of the effect of the method of quenching on the size of deformations. Compared to oil quenching, high-pressure gas quenching following vacuum carburizing resulted in more uniform and smaller deformations.

  17. Holographic quenches towards a Lifshitz point

    CERN Document Server

    Camilo, Giancarlo; Abdalla, Elcio

    2015-01-01

    We use the holographic duality to study quantum quenches of a strongly coupled CFT that drive the theory towards a non-relativistic fixed point with Lifshitz scaling. We consider the case of a Lifshitz dynamical exponent $z$ close to unity, where the non-relativistic field theory can be understood as a specific deformation of the corresponding CFT and, hence, the standard holographic dictionary can be applied. On the gravity side this amounts to finding a dynamical bulk solution which interpolates between AdS and Lishitz spacetimes as time evolves. We show that an asymptotically Lifshitz black hole is always formed in the final state. This indicates that it is impossible to reach the vacuum state of the Lifshitz theory from the CFT vacuum as a result of the proposed quenching mechanism. The nonequilibrium dynamics following the breaking of the relativistic scaling symmetry is also probed using both local and non-local observables. In particular, we conclude that the equilibration process happens in a top-down...

  18. A stop-restart solid propellant study with salt quench

    Science.gov (United States)

    Kumar, R. N.

    1976-01-01

    Experiments were conducted to gain insight into the unsatisfactory performance of the salt quench system of solid propellants in earlier studies. Nine open-air salt spray tests were conducted and high-speed cinematographic coverage was obtained of the events. It is shown that the salt spray by the detonator is generally a two-step process yielding two different fractions. The first fraction consists of finely powdered salt and moves practically unidirectionally at a high velocity (thousand of feet per second) while the second fraction consists of coarse particles and moves randomly at a low velocity (a few feet per second). Further investigation is required to verify the speculation that a lower quench charge ratio (weight of salt/propellant burning area) than previously employed may lead to an efficient quench

  19. Dynamical Outcomes of Quenching: Reflections on a Conical Intersection

    Science.gov (United States)

    Lehman, Julia H.; Lester, Marsha I.

    2014-04-01

    This review focuses on experimental studies of the dynamical outcomes following collisional quenching of electronically excited OH A2Σ+ radicals by molecular partners. The experimental observables include the branching between reactive and nonreactive decay channels, kinetic energy release, and quantum state distributions of the products. Complementary theoretical investigations reveal regions of strong nonadiabatic coupling, known as conical intersections, which facilitate the quenching process. The dynamical outcomes observed experimentally are connected to the local forces and geometric properties of the nuclei in the conical intersection region. Dynamical calculations for the benchmark OH-H2 system are in good accord with experimental observations, demonstrating that the outcomes reflect the strong coupling in the conical intersection region as the system evolves from the excited electronic state to quenched products.

  20. Jet quenching via jet collimation

    CERN Document Server

    Casalderrey-Solana, J; Wiedemann, U

    2011-01-01

    The strong modifications of dijet properties in heavy ion collisions measured by ATLAS and CMS provide important constraints on the dynamical mechanisms underlying jet quenching. In this work, we show that the transport of soft gluons away from the jet cone - jet collimation - can account for the observed dijet asymmetry with values of $\\hat{q}\\, L$ that lie in the expected order of magnitude. Further, we show that the energy loss attained through this mechanism results in a very mild distortion of the azimuthal angle dijet distribution.

  1. Jet Quenching via Jet Collimation

    CERN Document Server

    Casalderrey-Solana, Jorge; Wiedemann, Urs Achim

    2011-01-01

    The ATLAS Collaboration recently reported strong modifications of dijet properties in heavy ion collisions. In this work, we discuss to what extent these first data constrain already the microscopic mechanism underlying jet quenching. Simple kinematic arguments lead us to identify a frequency collimation mechanism via which the medium efficiently trims away the soft components of the jet parton shower. Through this mechanism, the observed dijet asymmetry can be accomodated with values of $\\hat{q}\\, L$ that lie in the expected order of magnitude.

  2. Modeling the formation of the quench product in municipal solid waste incineration (MSWI) bottom ash.

    Science.gov (United States)

    Inkaew, Kanawut; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki

    2016-06-01

    This study investigated changes in bottom ash morphology and mineralogy under lab-scale quenching conditions. The main purpose was to clarify the mechanisms behind the formation of the quench product/layer around bottom ash particles. In the experiments, the unquenched bottom ashes were heated to 300°C for 1h, and were quenched by warm water (65°C) with different simulated conditions. After having filtered and dried, the ashes were analyzed by a combination of methodologies namely, particle size distribution analysis, intact particle and thin-section observation, X-ray diffractometry, and scanning electron microscope with energy dispersive X-ray spectroscopy. The results indicated that after quenching, the morphology and mineralogy of the bottom ash changed significantly. The freshly quenched bottom ash was dominated by a quench product that was characterized by amorphous and microcrystalline calcium-silicate-hydrate (CSH) phases. This product also enclosed tiny minerals, glasses, ceramics, metals, and organic materials. The dominant mineral phases produced by quenching process and detected by XRD were calcite, Friedel's salt, hydrocalumite and portlandite. The formation of quench product was controlled by the fine fraction of the bottom ash (particle size ash-water reactions and formation of the quench product in the bottom ash was proposed.

  3. 基于模拟的热处理工艺设计:使淬火工艺与钢种和产品几何形状相匹配%Using Simulation for Heat Treatment Process Design:Matching Quenching Process with Steel Grade and Product Geometry

    Institute of Scientific and Technical Information of China (English)

    B.L.Ferguson; Z. Li

    2014-01-01

    The performance of steel parts is heavily dependent on the heat treatment process applied .The alloy content of the steel establishes the steel hardenability . The severity of the quenching establishes the local temperature history throughout the body of the part .In combination , the steel hardenability and the quenching process determine the final microstructure , mechanical properties , residual stress state and the performance of the part.The residual stress state , especially the surface stress state , is a significant factor in affecting fatigue life of the part.The steel hardenability and quenching practice can be adjusted to enhance residual surface compression and improve the fatigue life of a component .Computer simulation of the heat treatment process that includes calculation of the metallurgical phase transformations during the heating and cooling processes offers a method for scientifically designing the heat treatment process and selecting the steel alloy to optimise the performance of a particular product .In this paper , the DANTE heat treatment simulation software will be used to demonstrate this design methodology for a spur gear .%钢铁零件的性能主要决定于所采用的热处理工艺。钢的淬透性决定于合金元素含量,而淬火烈度确定了整个零件中不同部位的温度随时间变化过程。总的来说,零件最终的组织、力学性能、残余应力状态和服役性能均取决于钢的淬透性和淬火工艺。残余应力状态,特别是表面应力状态,是影响零件疲劳寿命的重要因素,可通过控制钢的淬透性和淬火工艺来提高零件的表面压应力,从而提高疲劳寿命。热处理工艺的计算机模拟,包括加热和冷却过程中的相变的计算,提供了一种科学地进行热处理工艺设计、钢种选择以优化某一特定产品性能的方法。本文采用热处理模拟软件DANTE来论证这种设计方法在正齿轮上的应用。

  4. Holographic quenches and anomalous transport

    Science.gov (United States)

    Ammon, Martin; Grieninger, Sebastian; Jimenez-Alba, Amadeo; Macedo, Rodrigo P.; Melgar, Luis

    2016-09-01

    We study the response of the chiral magnetic effect due to continuous quenches induced by time dependent electric fields within holography. Concretely, we consider a holographic model with dual chiral anomaly and compute the electric current parallel to a constant, homogeneous magnetic field and a time dependent electric field in the probe approximation. We explicitly solve the PDEs by means of pseudospectral methods in spatial and time directions and study the transition to an universal "fast" quench response. Moreover, we compute the amplitudes, i.e., residues of the quasi normal modes, by solving the (ODE) Laplace transformed equations. We investigate the possibility of considering the asymptotic growth rate of the amplitudes as a well defined notion of initial time scale for linearized systems. Finally, we highlight the existence of Landau level resonances in the electrical conductivity parallel to a magnetic field at finite frequency and show explicitly that these only appear in presence of the anomaly. We show that the existence of these resonances induces, among others, a long-lived AC electric current once the electric field is switched off.

  5. Neural Variability Quenching Predicts Individual Perceptual Abilities.

    Science.gov (United States)

    Arazi, Ayelet; Censor, Nitzan; Dinstein, Ilan

    2017-01-04

    Neural activity during repeated presentations of a sensory stimulus exhibits considerable trial-by-trial variability. Previous studies have reported that trial-by-trial neural variability is reduced (quenched) by the presentation of a stimulus. However, the functional significance and behavioral relevance of variability quenching and the potential physiological mechanisms that may drive it have been studied only rarely. Here, we recorded neural activity with EEG as subjects performed a two-interval forced-choice contrast discrimination task. Trial-by-trial neural variability was quenched by ∼40% after the presentation of the stimulus relative to the variability apparent before stimulus presentation, yet there were large differences in the magnitude of variability quenching across subjects. Individual magnitudes of quenching predicted individual discrimination capabilities such that subjects who exhibited larger quenching had smaller contrast discrimination thresholds and steeper psychometric function slopes. Furthermore, the magnitude of variability quenching was strongly correlated with a reduction in broadband EEG power after stimulus presentation. Our results suggest that neural variability quenching is achieved by reducing the amplitude of broadband neural oscillations after sensory input, which yields relatively more reproducible cortical activity across trials and enables superior perceptual abilities in individuals who quench more.

  6. A perturbative framework for jet quenching

    CERN Document Server

    Zapp, Korinna C; Wiedemann, Urs A

    2013-01-01

    We present a conceptually new framework for describing jet evolution in the dense medium produced in ultra-relativistic nucleus-nucleus collisions using perturbative QCD and its implementation into the Monte Carlo event generator JEWEL. The rescattering of hard partons in the medium is modelled by infrared continued pQCD matrix elements supplemented with parton showers. The latter approximate higher order real-emission matrix elements and thus generate medium-induced gluon emissions. The interplay between different emissions is governed by their formation times. The destructive interference between subsequent scattering processes, the non-Abelian version of the Landau-Pomeranchuk-Migdal effect, is also taken into account. In this way the complete radiation pattern is consistently treated in a uniform way. Results obtained within this minimal and theoretically well constrained framework are compared with a variety of experimental data susceptible to jet-quenching effects at both RHIC and the LHC. Overall, a go...

  7. Response functions after a quantum quench

    Science.gov (United States)

    Marcuzzi, Matteo; Gambassi, Andrea

    2014-04-01

    The response of physical systems to external perturbations can be used to probe both their equilibrium and nonequilibrium dynamics. While response and correlation functions are related in equilibrium by fluctuation-dissipation theorems, out of equilibrium they provide complementary information on the dynamics. In the past years, a method has been devised to map the quantum dynamics of an isolated extended system after a quench onto a static theory with boundaries in imaginary time; up to now, however, the focus was entirely on symmetrized correlation functions. Here we provide a prescription which, in principle, allows one to retrieve the whole set of relevant dynamical quantities characterizing the evolution, including linear response functions. We illustrate this construction with some relevant examples, showing in the process the emergence of light-cone effects similar to those observed in correlation functions.

  8. Quenching Simulation of PM Coated Tools

    Institute of Scientific and Technical Information of China (English)

    AxelHoftert; WernerTheisen; ChristophBroeckmann

    2004-01-01

    HIP cladding is a powder metallurgical coating technique used in the production of wear parts and tools. In many cases the composite components consist of carbide-free hot-work steel as base material and wear resistant carbide-rich PM cold-work steel as coating material. To ensure operativeness a heat tleatment matched to the substrate and coating material is required. Dissimilar phase tlansformation behaviour and different thermal expansion coefficients of layer and substrate entail inner stresses affecting the tlansformation kinetics in tam. In order to get a deeper insight into these effects Finite Element simulation tools are used. On the one hand, the tlansient heat conduction problem of the quenching process has to be solved. Non-linear boundary conditions and phase transformation of both, substrate and layer are considered. On the other hand, the mechanical response is calculated. The overall aim of the investigation is an improvement of common heat treatment techniques used for HIP cladded wear parts.

  9. Quenching Simulation of PM Coated Tools

    Institute of Scientific and Technical Information of China (English)

    Axel H(o)fter; Werner Theisen; Christoph Broeckmann

    2004-01-01

    HIP cladding is a powder metallurgical coating technique used in the production of wear parts and tools. In many cases the composite components consist of carbide-free hot-work steel as base material and wear resistant carbide-rich PM cold-work steel as coating material. To ensure operativeness a heat treatment matched to the substrate and coating material is required. Dissimilar phase transformation behaviour and different thermal expansion coefficients of layer and substrate entail inner stresses affecting the transformation kinetics in turn. In order to get a deeper insight into these effects Finite Element simulation tools are used. On the one hand, the transient heat conduction problem of the quenching process has to be solved. Non-linear boundary conditions and phase transformation of both, substrate and layer are considered. On the other hand, the mechanical response is calculated. The overall aim of the investigation is an improvement of common heat treatment techniques used for HIP cladded wear parts.

  10. Thermal quenching of fluorescence in condensed media

    Science.gov (United States)

    Lagos, Miguel; Paredes, Rodrigo

    2016-09-01

    Environmental factors strongly affect the features of the electromagnetic spectra of fluorescent compounds hosted by material media. The shape of the absorption and emission peaks, their characteristic asymmetry and breadth, the Stokes shift and quantum yield are generally temperature dependent and heavily influenced by both the local and extended physical properties of the medium. The theoretical method used before to obtain the lineshape function is extended here to other terms of the interaction energy between the optically sensitive orbital and the hosting medium, which become significant when the spectral feature is broad. An analytical expression for the temperature dependent decay rate by non-radiative processes is obtained by this way. Comparison with experiment on thermal quenching gives agreement within the experimental uncertainty. The solvent polarity, its protic or aprotic character, hydrogen bonds, proximity effects and presence of quenchers are expected to enter through the coupling constants of the corresponding energy terms.

  11. Neodymium Fluorescence Quenching by Hydroxyl Groups in Phosphate Laser Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ehrmann, P R; Carlson, K; Campbell, J H; Click, C A; Brow, R K

    2003-09-02

    Non-radiative losses due to OH fluorescence quenching of the Nd{sup 3+} {sup 4}F{sub 3/2} state are quantified over a range of OH concentrations from 4 x 10{sup 18}/cm{sup 3} to 4 x 10{sup 20}/cm{sup 3} and Nd doping levels from 0.4 to 9 x 10{sup 20}/cm{sup 3} in two K{sub 2}O-MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5} metaphosphate glasses having different K/Mg ratios ({approx}1/1 and 2/1). The quenching rate is found to vary linearly with the Nd and OH concentrations as predicted by Forster-Dexter theory. However, in contrast to theory the OH quenching rate extrapolates to a non-zero value at low Nd{sup 3+} doping levels. It is proposed that at low Nd{sup 3+} concentrations the OH is correlated with Nd sites in the glass. The quenching strength of OH on a per ion basis is found to be weak compared to other common transition metal impurities (e.g. Fe{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}). Nevertheless, OH dominates the Nd quenching in phosphate glass because under most processing conditions OH is present at concentrations 10{sup 2} to 10{sup 3} greater than transition metal ion impurities. A correlation of the quenching strength of OH and common metal impurity ions with the degree of spectral overlap of the impurity absorption bands and the four {sup 4}F{sub 3/2} to {sup 4}I{sub J} transitions shows good agreement.

  12. Mathematical Modeling of Acclimation Processes of the Photosynthetic Chain

    Directory of Open Access Journals (Sweden)

    S Heidari

    2016-10-01

    Full Text Available Introduction Photosynthetic energy conversion efficiency is characteristic of a system which is determined by interactions between various components of the system. The complex process of photosynthesis has been studied as a whole system which enables in silico examination of a large number of candidate genes for genetic engineering for a higher photosynthetic energy conversion efficiency. One of the most important environmental factors which influence the photosynthesis efficiency is light regime which can cause producing ROS components. To acclimate to such fluctuations, plants have evolved adaptive mechanisms to minimize damage of the photosynthetic apparatus excess light. A fast compatibility response to high light stresses is non-photochemical quenching process (NPQ, dissipating excessive energy to heat. Light harvested state switches into a quenched state by a conformational change of light harvesting complex (LHCII that regulated by xanthophylls and the PsbS protein within seconds. Low lumen pH activates xanthophyll synthesis via a xanthophyll cycle which consists of the de-epoxidation of violaxanthin to zeaxanthin by violaxanthin de-epoxidase in high light and inversely by zeaxanthin epoxidase in low light which occurs more slowly. Materials and Methods Thale cress (Arabidopsis thaliana (Chlombia-0 were grown on soil at 25/22 °C day/night temperature, with a 16/8 h photoperiod, and 40-70% (depend of plant species relative humidity. The light intensity was 150–200 µE m-2s-1 white light. Intensity of chlorophyll fluorescence was measured with PAM-2000 fluorometer (Heinz Walz, Germany and the manufacturer’s software (PamWin v.2. Results and Discussion In the present study, a dynamic kinetics amplified mathematical model was developed based on differential equations in order to predict short-term changes in NPQ in the process of adaptation to different light conditions. We investigated the stationary and dynamic behavior of the model

  13. HARDENING-RELATED DEFORMATIONS OF GEAR WHEELS AFTER VACUUM CARBURISING AND QUENCHING IN GAS

    Directory of Open Access Journals (Sweden)

    Wojciech Stachurski

    2017-03-01

    Full Text Available The purpose of modern surface hardening technology is obtaining reproducible, precisely planned parameters of the carburized layer, minimizing the negative phenomena that result in dimensional changes after hardening and making it possible to determine the nature and magnitude of these changes. This concerns mainly the concept of single-piece flow in heat treatment applied for the purposes of mass production, employing a special autonomous 4D Quenching chamber for high pressure gas quenching (HPGQ. The main components of the 4D Quenching chamber include a system of cooling nozzles surrounding the processed item and providing a uniform inflow of cooling gas from all directions (3D and a table rotating together with the item processed, contributing to uniform cooling (4D. Within the framework of this paper there was studied the impact of gear wheel quenching in a 4D Quenching chamber using nitrogen at pressure of 6 and 10 bar on changes in geometry. Geometric measurements of facewidth of gear, hole diameter and outside diameter were performed before and after carburization and quenching. The results obtained allowed us to determine the impact of quenching pressure inside a 4D Quenching chamber on dimensional changes in gear wheels analyzed. The thermo-chemical treatment resulted in a decrease in outside diameters and hole diameters measured and an increase in facewidth of gears.

  14. USE OF DIRECT QUENCHING AS AN ALTERNATIVE IN AUTOMOTIVE COMPONENTS MANUFACTURING

    Directory of Open Access Journals (Sweden)

    Hevlin Cristina de Almeida Costa

    2014-03-01

    Full Text Available This work has the aim to evaluate the replacement of quenching and hardening thermal treatment by direct quenching of forged safety washer component, to ensure and to maintain the mechanical properties of the products associated with competitive manufacturing costs. Supporting that, a statistical tool was used to delineate the processing routes, and forging tests were conducted at industrial scale. The effect of the different processing routes on the forged product was investigated through Finite Element Method and metallurgical analysis of the final product. The results showed the viability of the direct quenching with technical and economical advantages, once the control of the process parameters are guaranteed.

  15. Resonant quenching of Rydberg atomic states by highly polar molecules

    Science.gov (United States)

    Narits, A. A.; Mironchuk, E. S.; Lebedev, V. S.

    2016-06-01

    The results of theoretical studies of the resonant quenching and ion-pair formation processes induced by collisions of Rydberg atoms with highly polar molecules possessing small electron affinities are reported. We elaborate an approach for describing collisional dynamics of both processes and demonstrate the predominant role of resonant quenching channel of reaction for the destruction of Rydberg states by electron-attaching molecules. The approach is based on the solution of the coupled differential equations for the transition amplitudes between the ionic and Rydberg covalent terms of a quasimolecule formed during a collision of particles. It takes into account the possibility of the dipole-bound anion decay in the Coulomb field of the positive ionic core and generalizes previous models of charge-transfer processes involving Rydberg atoms to the cases, when the multistate Landau-Zener approaches become inapplicable. Our calculations for {{Rb}}({nl}) atom perturbed by {{{C}}}2{{{H}}}4{{SO}}3, {{CH}}2{CHCN}, {{CH}}3{{NO}}2, {{CH}}3{CN}, {{{C}}}3{{{H}}}2{{{O}}}3, and {{{C}}}3{{{H}}}4{{{O}}}3 molecules show that the curves representing the dependence of the resonant quenching cross sections on the principal quantum number n are bell-shaped with the positions of maxima being shifted towards lower values of n and the peak values, {σ }{max}({{q})}, several times higher than those for the ion-pair formation, {σ }{max}({{i})}. We obtain a simple power relation between the energy of electron affinity of a molecule and the position of maximum in n-dependence of the resonant quenching cross section. It can be used as an additional means for determining small binding energies of dipole-bound anions from the experimental data on resonant quenching of Rydberg states by highly polar molecules.

  16. QUENCHING OF STAR FORMATION IN SLOAN DIGITAL SKY SURVEY GROUPS: CENTRALS, SATELLITES, AND GALACTIC CONFORMITY

    Energy Technology Data Exchange (ETDEWEB)

    Knobel, Christian; Lilly, Simon J.; Woo, Joanna; Kovač, Katarina, E-mail: christian.knobel@phys.ethz.ch [Institute for Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland)

    2015-02-10

    We re-examine the fraction of low-redshift Sloan Digital Sky Survey satellites and centrals in which star formation has been quenched, using the environment quenching efficiency formalism that separates out the dependence of stellar mass. We show that the centrals of the groups containing the satellites are responding to the environment in the same way as their satellites (at least for stellar masses above 10{sup 10.3} M {sub ☉}), and that the well-known differences between satellites and the general set of centrals arise because the latter are overwhelmingly dominated by isolated galaxies. The widespread concept of ''satellite quenching'' as the cause of environmental effects in the galaxy population can therefore be generalized to ''group quenching''. We then explore the dependence of the quenching efficiency of satellites on overdensity, group-centric distance, halo mass, the stellar mass of the satellite, and the stellar mass and specific star formation rate (sSFR) of its central, trying to isolate the effect of these often interdependent variables. We emphasize the importance of the central sSFR in the quenching efficiency of the associated satellites, and develop the meaning of this ''galactic conformity'' effect in a probabilistic description of the quenching of galaxies. We show that conformity is strong, and that it varies strongly across parameter space. Several arguments then suggest that environmental quenching and mass quenching may be different manifestations of the same underlying process. The marked difference in the apparent mass dependencies of environment quenching and mass quenching which produces distinctive signatures in the mass functions of centrals and satellites will arise naturally, since, for satellites at least, the distributions of the environmental variables that we investigate in this work are essentially independent of the stellar mass of the satellite.

  17. Quenched QCD near the chiral limit

    CERN Document Server

    Göckeler, M; Petters, D; Pleiter, D; Rakow, P E L; Schierholz, G

    2000-01-01

    A numerical study of quenched QCD for light quarks is presented using O(a)improved fermions. Particular attention is paid to the possible existence anddetermination of quenched chiral logarithms. A `safe' region to use for chiralextrapolations appears to be at and above the strange quark mass.

  18. Monte Carlo Tools for Jet Quenching

    OpenAIRE

    Zapp, Korinna

    2011-01-01

    A thorough understanding of jet quenching on the basis of multi-particle final states and jet observables requires new theoretical tools. This talk summarises the status and propects of the theoretical description of jet quenching in terms of Monte Carlo generators.

  19. Quenched chiral perturbation theory to one loop

    NARCIS (Netherlands)

    Colangelo, Gilberto; Pallante, Elisabetta

    1998-01-01

    We calculate the divergences of the generating functional of quenched chiral perturbation theory at one loop, and renormalize the theory by an appropriate definition of the counterterms. We show that the quenched chiral logarithms can be accounted for by defining a renormalized B0 parameter which, a

  20. Quenched Chiral Perturbation Theory to one loop

    NARCIS (Netherlands)

    Colangelo, G.; Pallante, E.

    1998-01-01

    The divergences of the generating functional of quenched Chiral Perturbation theory (qCHPT) to one loop are computed in closed form. We show how the quenched chiral logarithms can be reabsorbed in the renormalization of the B0 parameter of the leading order Lagrangian. Finally, we do the chiral powe

  1. Thermal quenching and electron traps in LSO

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L.A. E-mail: kappers@uconnvm.uconn.edu; Bartram, R.H.; Hamilton, D.S.; Lempicki, A.; Glodo, J

    2003-05-01

    It is demonstrated by comparison of thermoluminescence and scintillation light outputs of LSO as functions of radiation time that a previously suggested thermal quenching correction is inappropriate. Approximate solutions of rate equations are employed to infer absolute trap concentrations and to explore the effects of thermal quenching on the shapes of thermoluminescence glow curves.

  2. MSFC Electrostatic Levitator (ESL) Rapid Quench System

    Science.gov (United States)

    SanSoucie, Michael P.; Craven, Paul D.; Rogers, Jan R.

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) Laboratory is a unique facility for investigators studying high-temperature materials. The laboratory boasts two levitators in which samples can be levitated, heated, melted, undercooled, and resolidified, all without the interference of a container or data-gathering instrument. The ESL main chamber has been upgraded with the addition of a rapid quench system. This system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy. Thereby allowing rapid quenching of undercooled liquid metals. Up to 8 quench vessels can be loaded into the quench wheel, which is indexed with LabVIEW control software. This allows up to 8 samples to be rapidly quenched before having to open the chamber. The system has been tested successfully on several zirconium samples. Future work will be done with other materials using different quench mediums. Microstructural analysis will also be done on successfully quench samples.

  3. Transient Loschmidt echo in quenched Ising chains

    Science.gov (United States)

    Lupo, Carla; Schiró, Marco

    2016-07-01

    We study the response to sudden local perturbations of highly excited quantum Ising spin chains. The key quantity encoding this response is the overlap between time-dependent wave functions, which we write as a transient Loschmidt Echo. Its asymptotics at long time differences contain crucial information about the structure of the highly excited nonequilibrium environment induced by the quench. We compute the echo perturbatively for a weak local quench but for arbitrarily large global quench, using a cumulant expansion. Our perturbative results suggest that the echo decays exponentially, rather than power law as in the low-energy orthogonality catastrophe, a further example of quench-induced decoherence already found in the case of quenched Luttinger liquids. The emerging decoherence scale is set by the strength of the local potential and the bulk excitation energy.

  4. Quench Heater Studies for the LHC Magnets

    CERN Document Server

    Rodríguez-Mateos, F

    2001-01-01

    About 2000 LHC (CERN's Large Hadron Collider) superconducting magnets will be protected with quench heaters against development of excessive voltage and overheating after a resistive transition. The quench heater strips are powered by capacitor bank discharge power supplies. The strips are made of stainless steel partially plated with copper to reduce their resistance and to allow for the connection of quench heaters in series. The strips are embedded in between two polyimide foils. The initial power density and the current decay time determine the quench heater effectiveness. Since only one type of heater power supply will be available, the copper plating cycle is adapted for the various magnet types to keep the resistance of the heater circuit constant. Different quench heater designs have been tested on various prototype magnets to optimise the copper-plating cycle and the electric insulation of the heater strip. This paper summarises the experimental results and computations that allowed to finalise the h...

  5. QUENCH STUDIES AND PREHEATING ANALYSIS OF SEAMLESS

    Energy Technology Data Exchange (ETDEWEB)

    Palczewski, Ari [JLAB; Geng, Rongli [JLAB; Eremeev, Grigory [JLAB

    2013-09-01

    One of the alternative manufacturing technologies for SRF cavities is hydroforming from seamless tubes. Although this technology has produced cavities with gradient and Q-values comparable to standard EBW/EP cavities, a few questions remain. One of these questions is whether the quench mechanism in hydroformed cavities is the same as in standard electron beam welded cavities. Towards this effort Jefferson Lab performed quench studies on 2 9 cell seamless hydroformed cavities. These cavities include DESY's - Z163 and Z164 nine-cell cavities hydroformed at DESY. Initial Rf test results Z163 were published in SRF2011. In this report we will present post JLAB surface re-treatment quench studies for each cavity. The data will include OST and T-mapping quench localization as well as quench location preheating analysis comparing them to the observations in standard electron beam welded cavities.

  6. A sound pressure field during the quenching of a steel specimen in different water solutions

    Directory of Open Access Journals (Sweden)

    J. Prezelj

    2011-01-01

    Full Text Available The purpose of controlling the quenching process of an orange-hot steel workpiece is to ensure its required surface hardness. A sound in a cooling liquid generated by the quenching process was experimentally analyzed. It contains sufficient information about the ongoing process for its quantification, and it can be used in real time. Traditionally, the quenching and the resultant hardening can be controlled by selecting different process parameters, like, for example the characteristics of the cooling liquid, the velocity of the cooling liquid flow, its temperature, the temperature of the work-piece, and many others. The possibility of controlling the quenching process by using acoustic cavitation is considered in this article.

  7. Galaxy formation in the Planck cosmology - IV. Mass and environmental quenching, conformity and clustering

    CERN Document Server

    Henriques, Bruno M B; Thomas, Peter A; Angulo, Raul E; Guo, Qi; Lemson, Gerard; Wang, Wenting

    2016-01-01

    We study the quenching of star formation as a function of redshift, environment and stellar mass in the galaxy formation simulations of Henriques et al. (2015), which implement an updated version of the Munich semi-analytic model (L-GALAXIES) on the two Millennium Simulations after scaling to a Planck cosmology. In this model massive galaxies are quenched by AGN feedback depending on both black hole and hot gas mass, and hence indirectly on stellar mass. In addition, satellite galaxies of any mass can be quenched by ram-pressure or tidal stripping of gas and through the suppression of gaseous infall. This combination of processes produces quenching efficiencies which depend on stellar mass, host halo mass, environment density, distance to group centre and group central galaxy properties in ways which agree qualitatively with observation. Some discrepancies remain in dense regions and close to group centres, where quenching still seems too efficient. In addition, although the mean stellar age of massive galaxi...

  8. Influence of quench rate and microstructure on bendability of AA6016 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Castany, P., E-mail: philippe.castany@insa-rennes.fr [Laboratoire de Metallurgie Mecanique, Institut des Materiaux, Station 12, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Diologent, F.; Rossoll, A. [Laboratoire de Metallurgie Mecanique, Institut des Materiaux, Station 12, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Despois, J.-F.; Bezencon, C. [Novelis Switzerland SA, 3960 Sierre (Switzerland); Mortensen, A., E-mail: andreas.mortensen@epfl.ch [Laboratoire de Metallurgie Mecanique, Institut des Materiaux, Station 12, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland)

    2013-01-01

    The influence of the quench rate after solution treatment on the bendability of AA6016 aluminum alloy sheets was investigated. Crack initiation during bending tests is found to be independent of quench rate whereas crack propagation is decreased after rapid quenching. A quantitative analysis of microstructures was carried out by transmission electron microscopy, focusing on grain boundary precipitates to correlate bending properties with microstructure. Crack initiation occurs by voiding at large micron-size intermetallic AlFeSi particles in shear bands, as previously proposed in the literature. Rapid quenching promotes the formation along grain boundaries of spherical Mg{sub 2}Si precipitates to the detriment of elongated Si precipitates that dominate after slow cooling. These Si grain boundary precipitates affect micro-voiding processes that drive crack propagation, which explains the observed dependence of the extent of cracking on quench rate. The grain boundary precipitate density has on the other hand no effect on crack initiation or propagation.

  9. On the O2(a1Δ) quenching by vibrationally excited ozone

    Science.gov (United States)

    Azyazov, V. N.; Mikheyev, P. A.; Heaven, M. C.

    2010-09-01

    The development of a discharge oxygen iodine laser (DOIL) requires efficient production of singlet delta oxygen (O2(a)) in electric discharge. It is important to understand the mechanisms by which O2(a) is quenched in these devices. To gain understanding of this mechanisms quenching of O2(a) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a) quenching were followed by observing the 1268 nm fluorescence of the O2 a --> X transition. Fast quenching of O2(a) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

  10. Galaxy Zoo: evidence for rapid, recent quenching within a population of AGN host galaxies

    Science.gov (United States)

    Smethurst, R. J.; Lintott, C. J.; Simmons, B. D.; Schawinski, K.; Bamford, S. P.; Cardamone, C. N.; Kruk, S. J.; Masters, K. L.; Urry, C. M.; Willett, K. W.; Wong, O. I.

    2016-12-01

    We present a population study of the star formation history of 1244 Type 2 active galactic nuclei (AGN) host galaxies, compared to 6107 inactive galaxies. A Bayesian method is used to determine individual galaxy star formation histories, which are then collated to visualize the distribution for quenching and quenched galaxies within each population. We find evidence for some of the Type 2 AGN host galaxies having undergone a rapid drop in their star formation rate within the last 2 Gyr. AGN feedback is therefore important at least for this population of galaxies. This result is not seen for the quenching and quenched inactive galaxies whose star formation histories are dominated by the effects of downsizing at earlier epochs, a secondary effect for the AGN host galaxies. We show that histories of rapid quenching cannot account fully for the quenching of all the star formation in a galaxy's lifetime across the population of quenched AGN host galaxies, and that histories of slower quenching, attributed to secular (non-violent) evolution, are also key in their evolution. This is in agreement with recent results showing that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes. The availability of gas in the reservoirs of a galaxy, and its ability to be replenished, appear to be the key drivers behind this co-evolution.

  11. Cooling Rate Study of Nickel-Rich Material During Thermal Treatment and Quench

    Science.gov (United States)

    Thomas, Fransua; Murguia, Silvia Briseno (Editor)

    2016-01-01

    To investigate quench cracking that results from water quenching after heat treatment of binary and Ni-rich material, cooling rates of specimens were measured during quenching and hardness post-thermal treatment. For specific applications binary Ni-Ti is customarily thermally treated and quenched to attain desired mechanical properties and hardness. However, one problem emerging from this method is thermal cracking, either during the heat treatment process or during the specimen's application. This can result in material and equipment failure as well as financial losses. The objective of the study is to investigate the internal cooling rate of 60-NiTi during quenching and determine possible factors causing thermal cracking. Cubic (1 in.3) samples of both material were heat treated in air at 1000 deg C for 2 hrs and quenched in room temperature water using two methods: (1) dropped in the water and (2) agitated in the water. Hardness of the two fore-mentioned methods was measured post heat treatment. Results indicate that the quenching method had an effect on cooling rate during quenching but hardness was observed to be essentially the same through the thickness of the samples.

  12. Overconsumption, outflows and the quenching of satellite galaxies

    Science.gov (United States)

    McGee, Sean L.; Bower, Richard G.; Balogh, Michael L.

    2014-07-01

    The baryon cycle of galaxies is a dynamic process involving the intake, consumption and ejection of vast quantities of gas. In contrast, the conventional picture of satellite galaxies has them methodically turning a large gas reservoir into stars until this reservoir is forcibly removed due to external ram pressure. This picture needs revision. Our modern understanding of the baryon cycle suggests that in some regimes the simple interruption of the fresh gas supply may quench satellite galaxies long before stripping events occur, a process we call overconsumption. We compile measurements from the literature of observed satellite quenching times at a range of redshifts to determine if satellites are principally quenched through orbit-based gas stripping events - either direct stripping of the disc (ram pressure stripping) or the extended gas halo (strangulation) - or from internally driven star formation outflows via overconsumption. These time-scales show significant deviations from the evolution expected for gas stripping mechanisms and suggest that either ram pressure stripping is much more efficient at high redshift, or that secular outflows quench satellites before orbit-based stripping occurs. Given the strong redshift evolution of star formation rates, at high redshift even moderate outflow rates will lead to extremely short delay times with the expectation that high-redshift (z > 1.5) satellites will be quenched almost immediately following the cessation of cosmological inflow. Observations of high-redshift satellites give an indirect but sensitive measure of the outflow rate, with current measurements suggesting that outflows are no larger than 2.5 times the star formation rate for galaxies with a stellar mass of 1010.5 M⊙.

  13. Fracture behavior of quenched poly(lactic acid

    Directory of Open Access Journals (Sweden)

    2011-01-01

    Full Text Available The effect of a quenching treatment applied on heated cast sheet extruded films of two poly(lactic acid (PLA commercial grades, with different optical purities, was studied. The thermal and mechanical properties of the films, as well as their fracture behavior, were assessed by differential scanning calorimetry (DSC, tensile tests, and the essential work of fracture (EWF approach. The heating-quenching treatment causes a de-aging effect with an increase in the free volume of polymer chains evidenced by a decrease in the glass transition temperature (Tg and a decrease in the tensile stiffness and yield stress. As a result, there is an abrupt increase in ductility, finding a dramatic change in the fracture behavior, from brittle to ductile. The use of digital image correlation (DIC of the strain field analysis during fracture testing has allowed relating the decrease on the yield stress promoted by quenching with the crack propagation kinetics. The use of the EWF method to characterize the fracture toughness of PLA has allowed to measure this enhancement on toughness, finding that the specific essential work of fracture (we and the plastic term (βwp parameters increased 120% and 1200%, respectively, after the quenching process.

  14. Boiling and quenching heat transfer advancement by nanoscale surface modification.

    Science.gov (United States)

    Hu, Hong; Xu, Cheng; Zhao, Yang; Ziegler, Kirk J; Chung, J N

    2017-07-21

    All power production, refrigeration, and advanced electronic systems depend on efficient heat transfer mechanisms for achieving high power density and best system efficiency. Breakthrough advancement in boiling and quenching phase-change heat transfer processes by nanoscale surface texturing can lead to higher energy transfer efficiencies, substantial energy savings, and global reduction in greenhouse gas emissions. This paper reports breakthrough advancements on both fronts of boiling and quenching. The critical heat flux (CHF) in boiling and the Leidenfrost point temperature (LPT) in quenching are the bottlenecks to the heat transfer advancements. As compared to a conventional aluminum surface, the current research reports a substantial enhancement of the CHF by 112% and an increase of the LPT by 40 K using an aluminum surface with anodized aluminum oxide (AAO) nanoporous texture finish. These heat transfer enhancements imply that the power density would increase by more than 100% and the quenching efficiency would be raised by 33%. A theory that links the nucleation potential of the surface to heat transfer rates has been developed and it successfully explains the current finding by revealing that the heat transfer modification and enhancement are mainly attributed to the superhydrophilic surface property and excessive nanoscale nucleation sites created by the nanoporous surface.

  15. Ballistic quench-induced correlation waves in ultracold gases

    CERN Document Server

    Corson, John P

    2016-01-01

    We investigate the wave packet dynamics of a pair of particles that undergoes a rapid change of scattering length. The short-range interactions are modeled in the zero-range limit, where the quench is accomplished by switching the boundary condition of the wave function at vanishing particle separation. This generates a correlation wave that propagates rapidly to nonzero particle separations. We have derived universal, analytic results for this process that lead to a simple phase-space picture of the quench-induced scattering. Intuitively, the strength of the correlation wave relates to the initial contact of the system. We find that, in one spatial dimension, the $k^{-4}$ tail of the momentum distribution contains a ballistic contribution that does not originate from short-range pair correlations, and a similar conclusion can hold in other dimensionalities depending on the quench protocol. We examine the resultant quench-induced transport in an optical lattice in 1D, and a semiclassical treatment is found to...

  16. Quenching phenomena in natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Umekawa, Hisashi; Ozawa, Mamoru [Kansai Univ., Osaka (Japan); Ishida, Naoki [Daihatsu Motor Company, Osaka (Japan)

    1995-09-01

    Quenching phenomena has been investigated experimentally using circulation loop of liquid nitrogen. During the quenching under natural circulation, the heat transfer mode changes from film boiling to nucleate boiling, and at the same time flux changes with time depending on the vapor generation rate and related two-phase flow characteristics. Moreover, density wave oscillations occur under a certain operating condition, which is closely related to the dynamic behavior of the cooling curve. The experimental results indicates that the occurrence of the density wave oscillation induces the deterioration of effective cooling of the heat surface in the film and the transition boiling regions, which results in the decrease in the quenching velocity.

  17. Superradiance Transition and Nonphotochemical Quenching in Photosynthetic Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Berman, Gennady Petrovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nesterov, Alexander [Universidad de Guadalajara, Departamento de Fısica, Jalisco (Mexico); Lopez, Gustavo [Universidad de Guadalajara, Departamento de Fısica, Jalisco (Mexico); Sayre, Richard Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-23

    Photosynthetic organisms have evolved protective strategies to allow them to survive in cases of intense sunlight fluctuation with the development of nonphotochemical quenching (NPQ). This process allows light harvesting complexes to transfer the excess sunlight energy to non-damaging quenching channels. This report compares the NPQ process with the superradiance transition (ST). We demonstrated that the maximum of the NPQ efficiency is caused by the ST to the sink associated with the CTS. However, experimental verifications are required in order to determine whether or not the NPQ regime is associated with the ST transition for real photosynthetic complexes. Indeed, it can happen that, in the photosynthetic apparatus, the NPQ regime occurs in the “non-optimal” region of parameters, and it could be independent of the ST.

  18. Numerical calculation of transient field effects in quenching superconducting magnets

    Energy Technology Data Exchange (ETDEWEB)

    Schwerg, Juljan Nikolai

    2010-07-01

    The maximum obtainable magnetic induction of accelerator magnets, relying on normal conducting cables and iron poles, is limited to around 2 T because of ohmic losses and iron saturation. Using superconducting cables, and employing permeable materials merely to reduce the fringe field, this limit can be exceeded and fields of more than 10 T can be obtained. A quench denotes the sudden transition from the superconducting to the normal conducting state. The drastic increase in electrical resistivity causes ohmic heating. The dissipated heat yields a temperature rise in the coil and causes the quench to propagate. The resulting high voltages and excessive temperatures can result in an irreversible damage of the magnet - to the extend of a cable melt-down. The quench behavior of a magnet depends on numerous factors, e.g. the magnet design, the applied magnet protection measures, the external electrical network, electrical and thermal material properties, and induced eddy current losses. The analysis and optimization of the quench behavior is an integral part of the construction of any superconducting magnet. The dissertation is divided in three complementary parts, i.e. the thesis, the detailed treatment and the appendix. In the thesis the quench process in superconducting accelerator magnets is studied. At first, we give an overview over features of accelerator magnets and physical phenomena occurring during a quench. For all relevant effects numerical models are introduced and adapted. The different models are weakly coupled in the quench algorithm and solved by means of an adaptive time-stepping method. This allows to resolve the variation of material properties as well as time constants. The quench model is validated by means of measurement data from magnets of the Large Hadron Collider. In a second step, we show results of protection studies for future accelerator magnets. The thesis ends with a summary of the results and a critical outlook on aspects which could

  19. Torus CLAS12-Superconducting Magnet Quench Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kashikhin, V S; Elouadhiri, L; Ghoshal, P K; Kashy, D; Makarov, A; Pastor, O; Quettier, L; Velev, G; Wiseman, M

    2014-06-01

    The JLAB Torus magnet system consists of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration. These coils are wound with SSC-36 Nb-Ti superconductor and have the peak magnetic field of 3.6 T. The first coil manufacturing based on the JLAB design began at FNAL. The large magnet system dimensions (8 m diameter and 14 MJ of stored energy) dictate the need for quench protection. Each coil is placed in an aluminum case mounted inside a cryostat and cooled by 4.6 K supercritical helium gas flowing through a copper tube attached to the coil ID. The large coil dimensions and small cryostat thickness drove the design to challenging technical solutions, suggesting that Lorentz forces due to transport currents and eddy currents during quench and various failure scenarios are analyzed. The paper covers the magnet system quench analysis using the OPERA3d Quench code.

  20. Quenching of the star formation activity in cluster galaxies

    Science.gov (United States)

    Boselli, A.; Roehlly, Y.; Fossati, M.; Buat, V.; Boissier, S.; Boquien, M.; Burgarella, D.; Ciesla, L.; Gavazzi, G.; Serra, P.

    2016-11-01

    We study the star formation quenching mechanism in cluster galaxies by fitting the spectral energy distribution (SED) of the Herschel Reference Survey, a complete volume-limited K-band-selected sample of nearby galaxies including objects in different density regions, from the core of the Virgo cluster to the general field. The SEDs of the target galaxies were fitted using the CIGALE SED modelling code. The truncated activity of cluster galaxies was parametrised using a specific star formation history with two free parameters, the quenching age QA and the quenching factor QF. These two parameters are crucial for the identification of the quenching mechanism, which acts on long timescales when starvation processes are at work, but is rapid and efficient when ram pressure occurs. To be sensitive to an abrupt and recent variation of the star formation activity, we combined twenty photometric bands in the UV to far-infrared in a new way with three age-sensitive Balmer line absorption indices extracted from available medium-resolution (R 1000) integrated spectroscopy and with Hα narrow-band imaging data. The use of a truncated star formation history significantly increases the quality of the fit in HI-deficient galaxies of the sample, that is to say, in those objects whose atomic gas content has been removed during the interaction with the hostile cluster environment. The typical quenching age of the perturbed late-type galaxies is QA ≲ 300 Myr whenever the activity of star formation is reduced by 50% 80%, while that of the quiescent early-type objects is QA ≃ 1-3 Gyr. The fraction of late-type galaxies with a star formation activity reduced by QF > 80% and with an HI-deficiency parameter HI-def > 0.4 drops by a factor of 5 from the inner half virial radius of the Virgo cluster (R/Rvir 4). The efficient quenching of the star formation activity observed in Virgo suggests that the dominant stripping process is ram pressure. We discuss the implication of this result in

  1. Evaluation of Important Factors Affecting Quench Distortion of Carburized Hypoid Gear with Shaft by Using Computer Simulation Methods

    Institute of Scientific and Technical Information of China (English)

    Tsuyoshi Sugimoto; Youichi Watanabe

    2004-01-01

    To minimize quenching distortion and dispersion, carburizing and quenching process conditions must be optimized; this includes the parts racking design used for quenching. We investigated some factors affecting carburized quenching distortion with an experiment using a hypoid gear having a shaft and with numerical simulation methods. The experimental results and those obtained from simulation were generally in agreement. Focusing on the surface temperature distribution in the gear, we studied quenching distortion characteristics in terms of changes in tooth profile and helix deviation. In our experiments, distortions occur during quenching in 373 K oil after austenitized temperature treatments conducted with various attitudes. We calculated the distortions by simulating the carburized oil-quenching process for the hypoid gear. Our results show large differences between the cooling rates of the tooth toe, middle section, and heel edges,and these greatly influence the change in tooth profile and helix deviation. We found that reducing the differences in temperatures on the gear surfaces during quenching is most important for minimizing the quench distortion of the hypoid gear.

  2. A perturbative framework for jet quenching

    Science.gov (United States)

    Zapp, Korinna C.; Krauss, Frank; Wiedemann, Urs A.

    2013-03-01

    We present a conceptually new framework for describing jet evolution in the dense medium produced in ultra-relativistic nucleus-nucleus collisions using perturbative QCD and its implementation into the Monte Carlo event generator Jewel. The rescattering of hard partons in the medium is modelled by infrared continued pQCD matrix elements supplemented with parton showers. The latter approximate higher order real-emission matrix elements and thus generate medium-induced gluon emissions. The interplay between different emissions is governed by their formation times. The destructive interference between subsequent scattering processes, the non-Abelian version of the Landau-Pomeranchuk-Migdal effect, is also taken into account. In this way the complete radiation pattern is consistently treated in a uniform way. Results obtained within this minimal and theoretically well constrained framework are compared with a variety of experimental data susceptible to jet-quenching effects at both RHIC and the LHC. Overall, a good agreement between data and simulation is found. This new framework also allows to identify and quantify the dominant uncertainties in the simulation, and we show some relevant examples for this.

  3. Quench Propagation in the Superconducting 6 kA Flexible Busbars of the LHC

    CERN Document Server

    Calvi, M; Pelegrin-Carcelen, J M; Sonnemann, F

    2002-01-01

    Flexible superconducting cables with currents up to 6 kA will be used to power magnets individually in the insertion regions of the LHC. In case of a quench, the currents in these circuits will decay very fast (with time constants of about 200 ms) such that relatively small copper cross sections are sufficient for these busbars. Quench propagation experiments on a prototype cable and corresponding simulations led to a detailed understanding of the quench behavior of these busbars and to recommendations for the design and application of the cable. Simulations of the quench process in a multi-strand conductor led to a detailed understanding of the way current crosses from superconducting to pure copper strands and how this affects the quench propagation velocity. At nominal current (6 kA), the quench propagation velocities are high (10 m/s) and the hot spot temperature increases rapidly. In this situation, timely quench detection and energy extraction (current reduction) are vital to prevent damage of circuit c...

  4. Binding Interaction of Captopril with Metal Ions: A Fluorescence Quenching Study

    Institute of Scientific and Technical Information of China (English)

    SIDDIQI K.S.; BANO Shaista; MOHD Ayaz; KHAN Aslam Aftab Parwaz

    2009-01-01

    The binding interaction of captopril(CPL)with biologically active metal ions Mg2+,Ca2+,Mn2+,Co2+,Ni2+,Cu2+ and Zn2+ was investigated in an aqueous acidic medium by fluorescence spectroscopy.The experimental results showed that the metal ions quenched the intrinsic fluorescence of CPL by forming CPL-metal complexes.It was found that static quenching was the main reason for the fluorescence quenching.The quenching constant in the case of Cu2+ was highest among all quenchers,perhaps due to its high nuclear charge and small size.Quenching of CPL by metal ions follows the order Cu2+> Ni2+> Co2+> Ca2+>Zn2+ > Mn2+ > Mg2+.The quenching constant Ksv,bimolecular quenching constant Kq,binding constant K and the binding sites "n" were determined together with their thermodynamic parameters at 27 and 37℃.The positive entropy change indicated the gain in configurational entropy as a result of chelation.The process of interaction was spontaneous and mainly △S-driven.

  5. Reduced quenching and extraction time for mammalian cells using filtration and syringe extraction.

    Science.gov (United States)

    Hernández Bort, Juan A; Shanmukam, Vinoth; Pabst, Martin; Windwarder, Markus; Neumann, Laura; Alchalabi, Ali; Krebiehl, Guido; Koellensperger, Gunda; Hann, Stephan; Sonntag, Denise; Altmann, Friedrich; Heel, Christine; Borth, Nicole

    2014-07-20

    In order to preserve the in vivo metabolite levels of cells, a quenching protocol must be quickly executed to avoid degradation of labile metabolites either chemically or biologically. In the case of mammalian cell cultures cultivated in complex media, a wash step previous to quenching is necessary to avoid contamination of the cell pellet with extracellular metabolites, which could distort the real intracellular concentration of metabolites. This is typically achieved either by one or multiple centrifugation/wash steps which delay the time until quenching (even harsh centrifugation requires several minutes for processing until the cells are quenched) or filtration. In this article, we describe and evaluate a two-step optimized protocol based on fast filtration by use of a vacuum pump for quenching and subsequent extraction of intracellular metabolites from CHO (Chinese hamster ovary) suspension cells, which uses commercially available components. The method allows transfer of washed cells into liquid nitrogen within 10-15s of sampling and recovers the entire extraction solution volume. It also has the advantage to remove residual filter filaments in the final sample, thus preventing damage to separation columns during subsequent MS analysis. Relative to other methods currently used in the literature, the resulting energy charge of intracellular adenosine nucleotides was increased to 0.94 compared to 0.90 with cold PBS quenching or 0.82 with cold methanol/AMBIC quenching.

  6. The Mass Dependance of Satellite Quenching in Milky Way-like Halos

    CERN Document Server

    Phillips, John I; Cooper, Michael C; Boylan-Kolchin, Michael; Bullock, James S; Tollerud, Erik

    2014-01-01

    Using the Sloan Digital Sky Survey, we examine the quenching of satellite galaxies around isolated Milky Way-like hosts in the local Universe. We find that the efficiency of satellite quenching around isolated galaxies is low and roughly constant over two orders of magnitude in satellite stellar mass ($M_{*}$ = $10^{8.5}-10^{10.5} \\, M_{\\odot}$), with only $\\sim~20\\%$ of systems quenched as a result of environmental processes. While largely independent of satellite stellar mass, satellite quenching does exhibit clear dependence on the properties of the host. We show that satellites of passive hosts are substantially more likely to be quenched than those of star-forming hosts, and we present evidence that more massive halos quench their satellites more efficiently. These results extend trends seen previously in more massive host halos and for higher satellite masses. Taken together, it appears that galaxies with stellar masses larger than about $10^{8}~M_{\\odot}$ are uniformly resistant to environmental quench...

  7. Temperature control for thermal treatment of aluminum alloy in a large-scale vertical quench furnace

    Institute of Scientific and Technical Information of China (English)

    沈玲; 贺建军; 喻寿益; 桂卫华

    2016-01-01

    The temperature control of the large-scale vertical quench furnace is very difficult due to its huge volume and complex thermal exchanges. To meet the technical requirement of the quenching process, a temperature control system which integrates temperature calibration and temperature uniformity control is developed for the thermal treatment of aluminum alloy workpieces in the large-scale vertical quench furnace. To obtain the aluminum alloy workpiece temperature, an air heat transfer model is newly established to describe the temperature gradient distribution so that the immeasurable workpiece temperature can be calibrated from the available thermocouple temperature. To satisfy the uniformity control of the furnace temperature, a second order partial differential equation (PDE) is derived to describe the thermal dynamics inside the vertical quench furnace. Based on the PDE, a decoupling matrix is constructed to solve the coupling issue and decouple the heating process into multiple independent heating subsystems. Then, using the expert control rule to find a compromise of temperature rising time and overshoot during the quenching process. The developed temperature control system has been successfully applied to a 31 m large-scale vertical quench furnace, and the industrial running results show the significant improvement of the temperature uniformity, lower overshoot and shortened processing time.

  8. Quenching of chlorophyll fluorescence induced by silver nanoparticles

    Science.gov (United States)

    Queiroz, A. M.; Mezacasa, A. V.; Graciano, D. E.; Falco, W. F.; M'Peko, J.-C.; Guimarães, F. E. G.; Lawson, T.; Colbeck, I.; Oliveira, S. L.; Caires, A. R. L.

    2016-11-01

    The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100 nm of diameter). UV-Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678 nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles.

  9. Electromagnetic stability of Nb{sub 3}Al superconductors fabricated by rapid quench and transform process (2); Kyunetsu Kyurei{center_dot}hentai ho ni yoru Nb{sub 3}Al senzai no denjiki teki anteisei (2)

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, K.; Suzuki, Y.; Wadayama, Y. [Hitachi Ltd., Tokyo (Japan). Hitachi Research Lab.; Nakagawa, K.; Tagawa, K.; Moriai, H. [Hitachi Cable, Ltd., Tokyo (Japan); Takeuchi, T.; Kiyoshi, T.; Wada, H. [National Research Institute for Metals, Tokyo (Japan)

    2000-05-29

    Nb{sub 3}Al multifilamentary wire was fabricated and the occurring situation of flux jump of it was investigated. Nb/NbAl elementary wire with diameter 1.25 mm fabricated by rapid heating and quenching method was coated by copper, and after fabricated to rectangular wire, it was heat-treated at 800 degrees of centigrade for ten hours. An elementary wire consists of 84 filaments. Flux jump was observed using SQUID. In field scan toward one direction, flux jump was not observed, but flux jump was observed in reversal magnetic field. However, magnetization did not decrease to zero. It was considered that Mb{sub 3}Al filament maintained superconductive state in spite of occurring transition of Nb region to normal conductive state by flux jump. (NEDO)

  10. Secondary Heating Under Quenching Cooling of Aluminum Alloys

    Science.gov (United States)

    Tsukrov, S. L.; Ber, L. B.

    2017-07-01

    Variants of secondary heating of aluminum alloys are considered, i.e., under quenching of plates in a water tank or on a horizontal quenching unit with water jet cooling, under continuous quenching of strips, and under quenching of tubes in vertical furnaces. Recommendation are given for removal or substantial reduction of the intensity of secondary heating under industrial conditions.

  11. Protein trafficking rates assessed by quantum dot quenching with bromocresol green

    OpenAIRE

    Valentine, Cathleen D.; Verkman, A.S.; Haggie, Peter M.

    2011-01-01

    Quantum dots are bright, photostable fluorophores used extensively to investigate biological processes. Here, we report that bromocresol green at low micromolar concentrations rapidly, efficiently and reversibly quenches the fluorescence of commercial quantum dots having a wide range of functionalities. The broad utility of bromocresol green quenching of quantum dots in cell biology is demonstrated in quantitative assays of trafficking of the β2-adrenergic receptor and the cystic fibrosis tra...

  12. Quench Protection of DI-BSCCO Coil

    Science.gov (United States)

    Yamaguchi, T.; Ueno, E.; Kato, T.; Hayashi, K.

    Quench protection is one of the most important requirements for the practical application of high-temperature-superconducting (HTS) coils. Quench protection requires that early detection of a developing quench event is followed by rapid reduction of the operating current. However, such quench detection is very difficult because HTS wire produces heat only locally due to the very slow propagation velocity of a normal zone. Excellent high voltage insulation performance is required if the current is to be reduced rapidly in a large-scale superconducting application with very large inductance. Thus it is important to investigate the behavior of coils with various decay time constants, and to detect voltages on very short time scales. This goal remains to be achieved. In the present study we built test coil and a full-scale pole coil for a 20 MW motor for use in experiments on quench protection, and parameterized the relation between the decay time constant and the detecting voltage, using a conventional balance circuit to detect the quench, which was generated by gradually raising the temperature of the coils. The results verify that a balance circuit can be used for quench detection. For example, when the current decay time constant is 4 seconds, the test coil can be protected even with a detecting voltage of 0.15 volts, despite a significant heat production rate of 126 W. We also confirmed that the full-scale pole coil, with a decay time constant of 20 seconds, can be protected with a detecting voltage of 0.06 V.

  13. Effect of Rapid Quenching on Electrochemical Properties of AB5 and AB3.5-Type Hydrogen Storage Alloys

    Institute of Scientific and Technical Information of China (English)

    Li Ping; Zheng Xueping; An Fuqiang; Islam S. Humail; Qu Xuanhui

    2007-01-01

    Effect of rapid quenching on the electrochemical properties of AB5 and AB3.5-type hydrogen storage alloys was studied. The results indicated that the discharge capacities of the rapid quenching MmNi3.55 Co0.75 Mn0.4Al0.3 alloys decrease under 25 and -35℃ with the increase of the quenching rate. Comparatively, the decrease extent of the quenching alloys at -35℃ is lower than that at 25℃. The result on the study of the cycle life indicated that the quenching process was favorable to improve the cycle stabilities of the MmNi3.55Co0.75-Mn0.4Al0.3alloys under 25 and -35℃. Whereas, the effect of the quenching process on the La0.7Mg0.3(Ni0.85Co0.15)3.5 alloy was different at 25℃ from at -35℃. Under 25℃, the cycle life of the alloy was obviously improved by the quenching process, however, the quenching process did not improve but decreased slightly the cycle life at -35℃.

  14. Microstructural Evolution of a Low-Carbon Steel during Application of Quenching and Partitioning Heat Treatments after Partial Austenitization

    NARCIS (Netherlands)

    Santofimia, M.J.; Zhao, L.; Sietsma, J.

    2008-01-01

    The “quenching and partitioning” (Q&P) process has been studied in a low-carbon steel containing 1.1 wt pct aluminum by heat treatments consisting of partial austenitization at 900 °C and subsequent rapid cooling to a quenching temperature in the range between 125 °C and 175 °C, followed by an isoth

  15. Microstructural Evolution of a Low-Carbon Steel during Application of Quenching and Partitioning Heat Treatments after Partial Austenitization

    NARCIS (Netherlands)

    Santofimia, M.J.; Zhao, L.; Sietsma, J.

    2008-01-01

    The “quenching and partitioning” (Q&P) process has been studied in a low-carbon steel containing 1.1 wt pct aluminum by heat treatments consisting of partial austenitization at 900 °C and subsequent rapid cooling to a quenching temperature in the range between 125 °C and 175 °C, followed by an

  16. Effects of quenching and partial quenching on QCD penguin matrix elements

    NARCIS (Netherlands)

    Golterman, Maarten; Pallante, Elisabetta

    2002-01-01

    We point out that chiral transformation properties of penguin operators change in the transition from unquenched to (partially) quenched QCD. The way in which this affects the lattice determination of weak matrix elements can be understood in the framework of (partially) quenched chiral perturbation

  17. Quench absorption coils: a quench protection concept for high-field superconducting accelerator magnets

    Science.gov (United States)

    Mentink, M.; Salmi, T.

    2017-06-01

    A quench protection concept based on coupled secondary coils is studied for inductively transferring energy out of a quenching superconducting dipole and thus limiting the peak hotspot temperature. So-called ‘quench absorption coils’ are placed in close proximity to the superconducting coils and are connected in series with a diode for the purpose of preventing current transformation during regular operation. During a quench, current is then transformed into the quench absorption coils so that a significant fraction of the stored magnetic energy is dissipated in the these coils. Numerical calculations are performed to determine the impact of such a concept and to evaluate the dimensions of the quench absorption coils needed to obtain significant benefits. A previously constructed 15 T Nb3Sn block coil is taken as a reference layout. Finite-element calculations are used to determine the combined inductive and thermal response of this system and these calculations are validated with a numerical model using an adiabatic approximation. The calculation results indicate that during a quench the presence of the quench absorption coils reduces the energy dissipated in the superconducting coils by 45% and reduces the hotspot temperature by over 100 K. In addition, the peak resistive voltage over the superconducting coils is significantly reduced. This suggests that this concept may prove useful for magnet designs in which the hotspot temperature is a design driver.

  18. Acrylamide-quenching of Rhizomucor miehei lipase.

    Science.gov (United States)

    Stobiecka, Agnieszka

    2005-07-01

    Steady-state and time-resolved fluorescence-quenching measurements have been performed to study multitryptophan lipase from filamentous fungus Rhizomucor miehei. Using the steady-state acrylamide fluorescence quenching data and the fluorescence-quenching-resolved-spectra (FQRS) method, the total emission spectrum of native ("closed-lid") lipase has been decomposed into two distinct spectral components accessible to acrylamide. According to FQRS analysis, more quenchable component has a maximum of fluorescence emission at about 352 nm whereas less quenchable component emits at about 332 nm. The redder component participates in about 60-64% of the total lipase fluorescence and may be characterized by the dynamic and static quenching constants equal to K(1) = 3.75 M(-1) and V(1) = 1.12 M(-1), respectively. The bluer component is quenchable via dynamic mechanism with K(2) = 1.97 M(-1). Significant difference in the values of acrylamide bimolecular rate quenching constants estimated for redder and bluer component (i.e., k(q) = 1.2 x 10 (9) M(-1)s (-1) vs. k(q) = 4.3 x 10(8) M(-1) s(-1), respectively), suggests that tryptophan residues in fungal lipase are not uniformly exposed to the solvent.

  19. Topological blocking in quantum quench dynamics

    Science.gov (United States)

    Kells, G.; Sen, D.; Slingerland, J. K.; Vishveshwara, S.

    2014-06-01

    We study the nonequilibrium dynamics of quenching through a quantum critical point in topological systems, focusing on one of their defining features: ground-state degeneracies and associated topological sectors. We present the notion of "topological blocking," experienced by the dynamics due to a mismatch in degeneracies between two phases, and we argue that the dynamic evolution of the quench depends strongly on the topological sector being probed. We demonstrate this interplay between quench and topology in models stemming from two extensively studied systems, the transverse Ising chain and the Kitaev honeycomb model. Through nonlocal maps of each of these systems, we effectively study spinless fermionic p-wave paired topological superconductors. Confining the systems to ring and toroidal geometries, respectively, enables us to cleanly address degeneracies, subtle issues of fermion occupation and parity, and mismatches between topological sectors. We show that various features of the quench, which are related to Kibble-Zurek physics, are sensitive to the topological sector being probed, in particular, the overlap between the time-evolved initial ground state and an appropriate low-energy state of the final Hamiltonian. While most of our study is confined to translationally invariant systems, where momentum is a convenient quantum number, we briefly consider the effect of disorder and illustrate how this can influence the quench in a qualitatively different way depending on the topological sector considered.

  20. Fluorescence self-quenching of tetraphenylporphyrin in liquid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Mihir [Integrated Science Education and Research Centre, Siksha-Bhavana, Visva-Bharati, Santiniketan 731235 (India); Nath, Sukhendu [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Hajra, Alakananda [Department of Chemistry, Siksha-Bhavana, Visva-Bharati, Santiniketan 731235 (India); Sinha, Subrata, E-mail: subratasinha67@rediffmail.com [Integrated Science Education and Research Centre, Siksha-Bhavana, Visva-Bharati, Santiniketan 731235 (India)

    2013-09-15

    Self-quenching of the fluorescence emission of tetraphenylporphyrin at high concentrations in toluene at the ambient temperature (300 K) is discussed in detail based on steady state and time-resolved fluorescence measurements. The fluorescence self-quenching is mainly attributed to re-absorption effect and the Förster type resonance energy transfer process (homotransfer). The re-absorption effect is found to deform the fluorescence emission spectra significantly in energy positions as well as relative intensities of different peaks at high concentrations. Nearly ideal fluorescence emission spectra are observed at a concentration ∼10{sup −7} mol/L. Moreover, there is an apparent enhancement of the fluorescence lifetime value of tetraphenylporphyrin in toluene at high concentrations, especially on the blue side of the fluorescence emission spectra. To the best knowledge of the authors, this is the first detail report on the fluorescence self-quenching of porphyrins in liquid medium. This finding carries great importance in view of the widespread research on porphyrins in the fields of solar light harvesting, artificial photosynthesis, photodynamic therapy, etc. -- Highlights: • The effect of concentration on the fluorescence emission spectra of tetraphenylporphyrin (TPhP) in toluene at 300 K is investigated by using steady state and time-resolved fluorescence techniques. • Both re-absorption effect and the Förster type resonance energy transfer are found to be responsible for the observed fluorescence self-quenching at high concentrations. • These investigations are extremely important in view of the extensive applications of porphyrins in the fabrication of molecular electronic devices, especially for solar and artificial photosynthetic devices, where highly concentrated porphyrins are often used for efficient light harvesting.

  1. 干熄焦炉内三维流动及传热的数值模拟%3D numerical simulation of flow and heat transfer in coke dry quenching process

    Institute of Scientific and Technical Information of China (English)

    常庆明; 靳振伟; 程平平; 李亚伟; 董良君

    2014-01-01

    A mathematical model for quenching gas flow and heat transfer between gas and coke in the coke dry quenching (CDQ) unit was established .In the model ,secondary development was done on the platform of Fluent by employing the user defined functions (UDF) and the user defined scalars (UDS) .The calculation results show a bias flow of quenching gas in the chutes ,i .e .more gas flows to the annular gas passage through the chutes near the outlet with relatively larger velocity .The pres-sure loss of the flowing gas mainly takes place in the cooling chamber ,and the heat transfer rate be-tween gas and coke near the side in the chamber is larger than that at the center .Simulation results find that the heated gas temperature can reach about 1101 K at the gas outlet w hile the cooled coke temperature decreases to about 439 K at the coke outlet w hen the circulating air volume is 200 000 m3/h .This can not only meet the cooling requirement of the coke but also supply the recycle gas with high grade heat for further heating or power generation .%以Fluent软件为平台,通过流体在多孔介质中的流动模型来处理冷却气体在干熄焦炉内的三维流动,借助于UDS和UDF进行二次开发,建立干熄焦炉内冷却气体及焦炭的流动传热模型,并分析了循环风量对气固换热的影响。结果表明,冷却室气体在通过斜道进入环形气道时有偏流现象,即靠近总出口附近的斜道有更多的气体流出,且气流速度最快;气体的压力损失主要发生在冷却室;冷却室内周边的换热效果比中心换热效果要好。模拟计算发现,循环风量为200000 m3/h时,换热后的冷却气体温度为1101 K ,焦炭温度为439 K ,这不仅满足了焦炭的冷却要求,而且还能提供用于供暖或发电的高品位热量的循环气体。

  2. Fluorescence Quenching Study of Zinc Bisporphyrins by Fulleropyrrolidines and Their N-Oxides

    Institute of Scientific and Technical Information of China (English)

    XU Hua; YANG Yi; ZHU Yi-Zhou; ZHENG Jian-Yu

    2006-01-01

    Novel phenylene-bridged zinc bisporphyrins (1-4), fulleropyrrolidines (C60-m, C60-h) and their N-oxides C6o-mo, C60-ho) were synthesized. The fluorescence quenching processes of bisporphyrins in toluene solution by fulleropyrrolidines and their N-oxides were investigated by steady-state fluorescence spectra. The fluorescence quenching constants proved that the fluorescence quenching ability was decreased as reduction of thepyrrolidinefunctionalgroups of fullerene surface: C60-h>C60-m>C60, and the fluorescence quenching ability was increased about 1.3-7.4 times by utilizing fulleropyrrolidine N-oxides (C60-mo, C60-ho) compared to fulleropyrrolidine compounds (C60-m, C60-h). The results revealed photoinduced electron transfer (PET) efficiencybetweenbisporphyrinandfullerenederivativescould be tunable by change of functional groups on fullerene surface.

  3. Thermal quench at finite 't Hooft coupling

    Directory of Open Access Journals (Sweden)

    H. Ebrahim

    2016-03-01

    Full Text Available Using holography we have studied thermal electric field quench for infinite and finite 't Hooft coupling constant. The set-up we consider here is D7-brane embedded in (α′ corrected AdS-black hole background. It is well-known that due to a time-dependent electric field on the probe brane, a time-dependent current will be produced and it will finally relax to its equilibrium value. We have studied the effect of different parameters of the system on equilibration time. As the most important results, for massless fundamental matter, we have observed a universal behaviour in the rescaled equilibration time in the very fast quench regime for different values of the temperature and α′ correction parameter. It seems that in the slow quench regime the system behaves adiabatically. We have also observed that the equilibration time decreases in finite 't Hooft coupling limit.

  4. Review of thermo-physical properties, wetting and heat transfer characteristics of nanofluids and their applicability in industrial quench heat treatment

    Directory of Open Access Journals (Sweden)

    Ramesh Gopalan

    2011-01-01

    Full Text Available Abstract The success of quenching process during industrial heat treatment mainly depends on the heat transfer characteristics of the quenching medium. In the case of quenching, the scope for redesigning the system or operational parameters for enhancing the heat transfer is very much limited and the emphasis should be on designing quench media with enhanced heat transfer characteristics. Recent studies on nanofluids have shown that these fluids offer improved wetting and heat transfer characteristics. Further water-based nanofluids are environment friendly as compared to mineral oil quench media. These potential advantages have led to the development of nanofluid-based quench media for heat treatment practices. In this article, thermo-physical properties, wetting and boiling heat transfer characteristics of nanofluids are reviewed and discussed. The unique thermal and heat transfer characteristics of nanofluids would be extremely useful for exploiting them as quench media for industrial heat treatment.

  5. Review of thermo-physical properties, wetting and heat transfer characteristics of nanofluids and their applicability in industrial quench heat treatment.

    Science.gov (United States)

    Ramesh, Gopalan; Prabhu, Narayan Kotekar

    2011-04-14

    The success of quenching process during industrial heat treatment mainly depends on the heat transfer characteristics of the quenching medium. In the case of quenching, the scope for redesigning the system or operational parameters for enhancing the heat transfer is very much limited and the emphasis should be on designing quench media with enhanced heat transfer characteristics. Recent studies on nanofluids have shown that these fluids offer improved wetting and heat transfer characteristics. Further water-based nanofluids are environment friendly as compared to mineral oil quench media. These potential advantages have led to the development of nanofluid-based quench media for heat treatment practices. In this article, thermo-physical properties, wetting and boiling heat transfer characteristics of nanofluids are reviewed and discussed. The unique thermal and heat transfer characteristics of nanofluids would be extremely useful for exploiting them as quench media for industrial heat treatment.

  6. Photoluminescence quenching of semiconducting polymer nanoparticles in presence of Au nanoparticles

    Indian Academy of Sciences (India)

    Santanu Bhattacharyya; Amitava Patra

    2012-10-01

    In this report, we have demonstrated the photoluminescence quenching and energy transfer properties of semiconducting polymer nanoparticles, poly (N-vinylcarbazole) (PVK) in presence of different sized Au nanoparticles by steady state and time-resolved spectroscopy. We have described the quenching phenomena by sphere of action static quenching mechanism and both dynamic and static quenching processes are found in these systems. PL quenching values are 24.22% and 57.3% for 14 nm and 18 nm Au nanoparticles, respectively. It is found that the radiative and nonradiative decay have been modified with the size of Au nanoparticles. PL quenching and shortening of decay time regarding polymer nanoparticles in presence of Au nanoparticles suggest the nonradiative energy transfer process. The values of energy transfer are 6.7%, 49.5% and 53.38% from PVK polymer nanoparticles to 3 nm, 14 nm and 18 nm Au nanoparticles, respectively. Using FRET and SET equations we have calculated the average distance of donor PVK polymer nanoparticles and acceptor Au nanoparticles.

  7. Proton-transfer mediated quenching of pyrene/indole charge-transfer states in isooctane solutions.

    Science.gov (United States)

    Altamirano, Marcela S; Bohorquez, María del Valle; Previtali, Carlos M; Chesta, Carlos A

    2008-01-31

    The fluorescence quenching of pyrene (Py) by a series of N-methyl and N-H substituted indoles was studied in isooctane at 298 K. The fluorescence quenching rate constants were evaluated by mean of steady-state and time-resolved measurements. In all cases, the quenching process involves a charge-transfer (CT) mechanism. The I(o)/I and tau(o)/tau Stern-Volmer plots obtained for the N-H indoles show a very unusual upward deviation with increasing concentration of the quenchers. This behavior is attributed to the self-quenching of the CT intermediates by the free indoles in solution. The efficiency of quenching of the polyaromatic by the N-H indoles increases abruptly in the presence of small amount of added pyridine (or propanol). A detailed analysis of the experimental data obtained in the presence of pyridine provides unambiguous evidence that the self-quenching process involves proton transfer from the CT states to indoles.

  8. Quench in high temperature superconductor magnets

    CERN Document Server

    Schwartz, J

    2013-01-01

    High field superconducting magnets using high temperature superconductors are being developed for high energy physics, nuclear magnetic resonance and energy storage applications. Although the conductor technology has progressed to the point where such large magnets can be readily envisioned, quench protection remains a key challenge. It is well-established that quench propagation in HTS magnets is very slow and this brings new challenges that must be addressed. In this paper, these challenges are discussed and potential solutions, driven by new technologies such as optical fiber based sensors and thermally conducting electrical insulators, are reviewed.

  9. Quench propagation analysis in adiabatic superconducting windings

    Energy Technology Data Exchange (ETDEWEB)

    Ishiyama, A.; Matsumura, H.; Takita, W. (Dept. of Electrical Engineering, Waseda Univ., Tokyo (JP)); Iwasa, Y (Massachusetts Inst. of Tech., Cambridge, MA (United States). Francis Bitter National Magnet Lab.)

    1991-03-01

    This paper reports the basic postulate of the author's quench simulation code, developed to analyze normal-zone propagation in adiabatic magnets which is the code's computation may be immensely simplified without sacrifice in accuracy by aggregating all thermal properties of the winding affecting normal-zone propagation into a single parameter of the transverse quench velocity. In order to verify this postulate, a finite element method (FEM) analysis has been applied to solve the temporal and spatial evolution of temperature within a section of an adiabatic magnet winding.

  10. Event-Shape Engineering and Jet Quenching

    CERN Document Server

    Christiansen, Peter

    2016-01-01

    Event-Shape Engineering (ESE) is a tool that enables some control of the initial geometry in heavy-ion collisions in a similar way as the centrality enables some control of the number of participants. Utilizing ESE, the path length in and out-of plane can be varied while keeping the medium properties (centrality) fixed. In this proceeding it is argued that this provides additional experimental information about jet quenching. Finally, it is suggested that if ESE studies are done in parallel for light and heavy quarks one can determine, in a model independent way, if the path-length dependence of their quenching differs.

  11. Investigating jet quenching on the lattice

    CERN Document Server

    Panero, Marco; Schäfer, Andreas

    2014-01-01

    Due to the dynamical, real-time, nature of the phenomenon, the study of jet quenching via lattice QCD simulations is not straightforward. In this contribution, however, we show how one can extract information about the momentum broadening of a hard parton moving in the quark-gluon plasma, from lattice calculations. After discussing the basic idea (originally proposed by Caron-Huot), we present a recent study, in which we estimated the jet quenching parameter non-perturbatively, from the lattice evaluation of a particular set of gauge-invariant operators.

  12. Application of Best Estimate Approach for Modelling of QUENCH-03 and QUENCH-06 Experiments

    Directory of Open Access Journals (Sweden)

    Tadas Kaliatka

    2016-04-01

    In this article, the QUENCH-03 and QUENCH-06 experiments are modelled using ASTEC and RELAP/SCDAPSIM codes. For the uncertainty and sensitivity analysis, SUSA3.5 and SUNSET tools were used. The article demonstrates that applying the best estimate approach, it is possible to develop basic QUENCH input deck and to develop the two sets of input parameters, covering maximal and minimal ranges of uncertainties. These allow simulating different (but with the same nature tests, receiving calculation results with the evaluated range of uncertainties.

  13. Validation of Quench Simulation and Simulation of the TWIN Solenoid

    CERN Document Server

    Pots, Rosalinde Hendrika

    2015-01-01

    For the Future Circular Collider at CERN a multi-purpose detector is proposed. The 6T TWIN Solenoid, a very large magnet system with a stored energy of 53 GJ, is being designed. It is important to protect the magnet against quenches in the system. Therefore several existing quench protection systems are evaluated and simulations have be performed on quenches in the TWIN Solenoid. The simulations on quenches in the TWIN Solenoid have been performed with promising results; the hotspot temperatures do not exceed 120 K and layer to layer voltages stay below 500 V. Adding quench heaters to the system might improve the quench protection system further.

  14. Analysis of superconducting cavity quench events at SSRF

    Institute of Scientific and Technical Information of China (English)

    HOU Hong-Tao; LI Zheng; LIU Jian-Fei; ZHAO Yu-Bin; ZHAO Shen-jie; ZHANG Zhi-Gang; LUO Chen; FENG Zi-Qiang; MAO Dong-Qing; ZHENG Xiang

    2011-01-01

    Quench is important and dangerous to superconducting RF cavities. This paper illustrates the mechanism of quench and how a quench detector works, and analyzes the quench events happening during beam operations and cavity conditioning. We find that the quench protection is mostly triggered by some reasons such as fluctuation of cavity voltage, multipacting or arc, rather than a real cavity thermal breakdown. The results will be beneficial to optimize the operation parameters of superconducting cavities, to discover the real reasons for beam trip by quench interlock, and to improve the operation stability of superconducting RF systems.

  15. Quenched heavy-light decay constants

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, R.M.; Booth, S.P.; Bowler, K.C.; Collins, S.; Henty, D.S.; Kenway, R.D.; Richards, D.G.; Shanahan, H.P.; Simone, J.N.; Simpson, A.D.; Wilkes, B.E. (Department of Physics, The University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)); Ewing, A.K.; Lellouch, L.; Sachrajda, C.T.; Wittig, H. (Physics Department, The University, Southampton SO9 5NH (United Kingdom)); (UKQCD Collaboration)

    1994-02-01

    We present results for heavy-light decay constants, using both propagating quarks and the static approximation, in [ital O]([ital a])-improved, quenched lattice QCD. At [beta]=6.2 on a 24[sup 3][times]48 lattice we find [ital f][sub [ital D

  16. Lattice QCD simulations beyond the quenched approximation

    Energy Technology Data Exchange (ETDEWEB)

    Ukawa, A. (European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.)

    1989-07-01

    Present status of lattice QCD simulations incorporating the effects of dynamical quarks is presented. After a brief review of the formalism of lattice QCD, the dynamical fermion algorithms in use today are described. Recent attempts at the hadron mass calculation are discussed in relation to the quenched results, and current understanding on the finite temperature behavior of QCD is summarized. (orig.).

  17. Galaxy formation in the Planck cosmology - IV. Mass and environmental quenching, conformity and clustering

    Science.gov (United States)

    Henriques, Bruno M. B.; White, Simon D. M.; Thomas, Peter A.; Angulo, Raul E.; Guo, Qi; Lemson, Gerard; Wang, Wenting

    2017-08-01

    We study the quenching of star formation as a function of redshift, environment and stellar mass in the galaxy formation simulations of Henriques et al. (2015), which implement an updated version of the Munich semi-analytic model (L-GALAXIES) on the two Millennium Simulations after scaling to a Planck cosmology. In this model, massive galaxies are quenched by active galactic nucleus (AGN) feedback depending on both black hole and hot gas mass, and hence indirectly on stellar mass. In addition, satellite galaxies of any mass can be quenched by ram-pressure or tidal stripping of gas and through the suppression of gaseous infall. This combination of processes produces quenching efficiencies which depend on stellar mass, host halo mass, environment density, distance to group centre and group central galaxy properties in ways which agree qualitatively with observation. Some discrepancies remain in dense regions and close to group centres, where quenching still seems too efficient. In addition, although the mean stellar age of massive galaxies agrees with observation, the assumed AGN feedback model allows too much ongoing star formation at late times. The fact that both AGN feedback and environmental effects are stronger in higher density environments leads to a correlation between the quenching of central and satellite galaxies which roughly reproduces observed conformity trends inside haloes.

  18. Fluorescence quenching behaviour of uric acid interacting with water-soluble cationic porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Makarska-Bialokoz, Magdalena, E-mail: makarska@hektor.umcs.lublin.pl [Department of Inorganic Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 2, 20-031 Lublin (Poland); Borowski, Piotr [Faculty of Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 3, 20-031 Lublin (Poland)

    2015-04-15

    The process of association between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H{sub 2}TTMePP) and uric acid as well as its sodium salt has been studied in aqueous NaOH solution analysing its absorption and steady-state fluorescence spectra. The fluorescence quenching effect observed during interactions porphyrin-uric acid compounds points at the fractional accessibility of the fluorophore for the quencher. The association and fluorescence quenching constants are of the order of magnitude of 10{sup 5} mol{sup −1}. The fluorescence lifetimes and the quantum yields of the porphyrin anionic form were established. The results demonstrate that uric acid and its sodium salt can interact with H{sub 2}TTMePP at basic pH and through formation of stacking complexes are able to quench its ability to emission. - Highlights: • Association study of water soluble cationic porphyrin with uric acid. • Porphyrin absorption spectra undergo the bathochromic and hypochromic effects. • Uric acid interacts with porphyrin in inhibiting manner, quenching its emission. • Fluorescence quenching effect testifies for the partial inactivation of a porphyrin. • The association and fluorescence quenching constants were calculated.

  19. Satellite quenching time-scales in clusters from projected phase space measurements matched to simulated orbits

    Science.gov (United States)

    Oman, Kyle A.; Hudson, Michael J.

    2016-12-01

    We measure the star formation quenching efficiency and time-scale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed Sloan Digital Sky Survey galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample (109-10^{11.5}M_{⊙}) by massive (> 10^{13} M_{⊙}) clusters is essentially 100 per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first pericentric passage. There is little variation in the onset of quenching from galaxy-to-galaxy: the spread in this time is at most ˜2 Gyr at fixed M*. Higher mass satellites quench earlier, with very little dependence on host cluster mass in the range probed by our sample.

  20. Near-infrared induced optical quenching effects on mid-infrared quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Dingkai, E-mail: dingk1@umbc.edu; Talukder, Muhammad Anisuzzaman; Chen, Xing [Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Cai, Hong [Center of Advanced Studies in Photonics Research (CASPR), University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Johnson, Anthony M.; Choa, Fow-Sen [Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Center of Advanced Studies in Photonics Research (CASPR), University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Khurgin, Jacob B. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2014-06-23

    In space communications, atmospheric absorption and Rayleigh scattering are the dominant channel impairments. Transmission using mid-infrared (MIR) wavelengths offers the benefits of lower loss and less scintillation effects. In this work, we report the telecom wavelengths (1.55 μm and 1.3 μm) induced optical quenching effects on MIR quantum cascade lasers (QCLs), when QCLs are operated well above their thresholds. The QCL output power can be near 100% quenched using 20 mW of near-infrared (NIR) power, and the quenching effect depends on the input NIR intensity as well as wavelength. Time resolved measurement was conducted to explore the quenching mechanism. The measured recovery time is around 14 ns, which indicates that NIR generated electron-hole pairs may play a key role in the quenching process. The photocarrier created local field and band bending can effectively deteriorate the dipole transition matrix element and quench the QCL. As a result, MIR QCLs can be used as an optical modulator and switch controlled by NIR lasers. They can also be used as “converters” to convert telecom optical signals into MIR optical signals.

  1. Fluorescence quenching of fluoroquinolone antibiotics by 4-hydroxy-TEMPO in aqueous solution.

    Science.gov (United States)

    Żamojć, Krzysztof; Wiczk, Wiesław; Zaborowski, Bartłomiej; Makowski, Mariusz; Pranczk, Joanna; Jacewicz, Dagmara; Chmurzyński, Lech

    2014-12-10

    The fluorescence quenching of norfloxacin, danofloxacin, enrofloxacin and levofloxacin, belonging to a group of fluoroquinolone antibiotics, by 4-hydroxy-TEMPO was studied in aqueous solutions with the use of steady-state, time-resolved fluorescence spectroscopy as well as UV-VIS absorption spectroscopy methods. In order to understand the mechanism of quenching the absorption and fluorescence emission spectra of all fluoroquinolone antibiotics studied as well as decreases of their fluorescence were registered as a function of the 4-hydroxy-TEMPO concentration. No deviations from a linearity in the Stern-Volmer plots (determined from both, steady-state and time-resolved measurements) were observed. The fluorescence quenching mechanism was proved to be totally dynamic, what was additionally confirmed by the registration of Stern-Volmer plots at 5 temperatures ranging from 15 to 55°C. On the basis of theoretical calculations of fluoroquinolones' molecular radii and ionization potentials the mechanism of electron transfer was rejected. It seems that the fluorescence quenching is diffusion-limited and is caused by the increase of nonradiative processes, such as internal conversion or intersystem crossing. The Stern-Volmer quenching constants and bimolecular quenching constants were determined at the room temperature for all fluoroquinolone antibiotics studied. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Efficiency and quality of inductive heating and quenching of planetary shafts

    Directory of Open Access Journals (Sweden)

    B. Kosec

    2012-01-01

    Full Text Available Presented work discusses a complex process of inductive heating and quenching of carbon steel planetary shafts for diesel engine starters. On the measurements base of temperature fi elds on the surface of the planetary shafts by thermographic camera and theoretical knowledge, a mathematical model for temperature conditions determination in the shaft during the entire process of heating and quenching was carried out. On the basis of developed mathematical model a computer program was developed, and used for analyses and induction hardening process optimization of planetary shafts.

  3. Flexible Furnace Concepts for Vacuum Heat Treatment Combined with High-pressure Gas Quenching

    Institute of Scientific and Technical Information of China (English)

    Karl Ritter; Stefan Wiebach

    2004-01-01

    IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.

  4. Simulation of the Quench-06 experiment with Scdapsim; Simulacion del experimento Quench-06 con Scdapsim

    Energy Technology Data Exchange (ETDEWEB)

    Angel M, E. del; Nunez C, A.; Amador G, R. [CNSNS, Dr. Barragan No. 779, 03020 Mexico D.F. (Mexico)]. e-mail: edangelm@cnsns.gob.mx

    2003-07-01

    The present work describes the pattern of the called Quench installation developed and used by the National Commission of Nuclear Security and Safeguards (CNSNS) for their participation in the International Standard Problem 45 (ISP), organized by the Nuclear Energy Agency (NEA). The exercise consisted on the simulation of the denominated experiment Quench-06 carried out in the experimental installation Quench located in the Forschungszentrum laboratory in Karlsruhe, Germany. The experiment Quench-06 consisted on simulating the sudden and late injection of water in a fuel assemble for a pressurized reactor (PWR). The CNSNS uses the version bd of the SCDAPSIM code developed by the company Innovative Software Systems (ISS) to simulate this experiment. The obtained results showed that the code is able to predict the experiment partially when overestimating the hydrogen production and of the partial fused of some fuel pellets, but predicting correctly the damage in the shroud. (Author)

  5. Fluorescence quenching of CdS quantum dots by 4-azetidinyl-7-nitrobenz-2-oxa-1,3-diazole: a mechanistic study.

    Science.gov (United States)

    Santhosh, Kotni; Patra, Satyajit; Soumya, S; Khara, Dinesh Chandra; Samanta, Anunay

    2011-10-24

    Fluorescence quenching of CdS quantum dots (QDs) by 4-azetidinyl-7-nitrobenz-2-oxa-1,3-diazole (NBD), where the two quenching partners satisfy the spectral overlap criterion necessary for Förster resonance energy transfer (FRET), is studied by steady-state and time-resolved fluorescence techniques. The fluorescence quenching of the QDs is accompanied by an enhancement of the acceptor fluorescence and a reduction of the average fluorescence lifetime of the donor. Even though these observations are suggestive of a dynamic energy transfer process, it is shown that the quenching actually proceeds through a static interaction between the quenching partners and is probably mediated by charge-transfer interactions. The bimolecular quenching rate constant estimated from the Stern-Volmer plot of the fluorescence intensities, is found to be exceptionally high and unrealistic for the dynamic quenching process. Hence, a kinetic model is employed for the estimation of actual quencher/QD ratio dependent exciton quenching rate constants of the fluorescence quenching of CdS by NBD. The present results point to the need for a deeper analysis of the experimental quenching data to avoid erroneous conclusions.

  6. A comparative study on fluorescence quenching of CdTe nanocrystals with a serial of polycyclic aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Baslak, Canan, E-mail: cananbaslak@gmail.com [Advanced Technology Research and Application Center, Selcuk University, 42075 Konya (Turkey); Department of Chemistry, Faculty of Science, Selcuk University, 42075 Konya (Turkey); Kus, Mahmut, E-mail: mahmutkus1@gmail.com [Advanced Technology Research and Application Center, Selcuk University, 42075 Konya (Turkey); Department of Chemical Engineering, Faculty of Engineering, Selcuk University, 42075 Konya (Turkey); Cengeloglu, Yunus [Department of Chemistry, Faculty of Science, Selcuk University, 42075 Konya (Turkey); Ersoz, Mustafa [Advanced Technology Research and Application Center, Selcuk University, 42075 Konya (Turkey); Department of Chemistry, Faculty of Science, Selcuk University, 42075 Konya (Turkey)

    2014-09-15

    We report sensing different polycyclic aromatic hydrocarbons (PAHs) with colloidal CdTe nanocrystals. The effect of molecular structure on quenching rate for 2-hyroxy-1-naphthaldehyde (2H–1N), 9,10-phenanthraquinone (PQ), 9-anthracenecarboxaldehyde (9-AC) and quinoline (Q) is presented. The quenching rate constants are observed to be strongly dependent on the molecular structure. PQ, consisting of two carbonyl groups, shows the highest rate constant while Q shows the worst one. Both static and dynamic quenching are simultaneously observed for PQ and 2H–1N. Therefore extended Stern–Volmer equations are used to calculate rate constants. Results showed that dynamic quenching is a dominant process. The rate constants for PQ, 2H–1N, 9-AC and Q are calculated to be 64.84, 10.73, 10.66 and 1.85 respectively. - Highlights: • We report the fluorescence quenching of colloidal CdTe nanocrystals with different polycyclic aromatic hydrocarbons. • The quenching rate constants are observed to be strongly dependent on the molecular structure. • Static and dynamic quenching are simultaneously observed. • The best quenching was observed for 9,10-phenanthraquinone.

  7. The formation of nuggets of highly siderophile elements in quenched silicate melts at high temperatures: Before or during the silicate quench?

    Science.gov (United States)

    Malavergne, V.; Charon, E.; Jones, J.; Cordier, P.; Righter, K.; Deldicque, D.; Hennet, L.

    2016-01-01

    that the nuggets acted as nucleation sites during the quench. Thus they predated the quench. Finally, these nuggets also had strong heterogeneities suggesting at least a two-stage formation process under reducing conditions. Consequently, our observations clearly show that these HSE nuggets formed before the quench in the silicate melt. Our results agreed with previous studies, which concluded that HSE abundances in the Earth's mantle require the late accretion of chondritic material subsequent to core formation. However, the effects of metallic Si, O, H, or the effect of pressure on the HSE partitioning are still not fully understood. Further work to constrain these effects is to be encouraged to understand the Earth's core formation.

  8. Simulation of bundle test Quench-12 with integral code MELCOR

    Energy Technology Data Exchange (ETDEWEB)

    Duspiva, J. [Nuclear Research Inst., Rez plc (Czech Republic)

    2011-07-01

    The past NRI analyses cover the Quench-01, Quench-03 and Quench-06 with version MELCOR 1.8.5 (including reflood model), and Quench-01 and Quench-11 tests with the latest version MELCOR 1.8.6. The Quench-12 test is specific, because it has different bundle configuration related to the VVER bundle configuration with hexagonal grid of pins and also used E110 cladding material. Specificity of Quench-12 test is also in the used material of fuel rod cladding - E110. The test specificities are a reason for the highest concern, because the VVER reactors are operated in the Czech Republic. The new input model was developed with the taking into account all experience from previous simulations of the Quench bundle tests. The recent version MELCOR 1.8.6 YU{sub 2}911 was used for the simulation with slightly modified ELHEAT package. Sensitivity studies on input parameters and oxidation kinetics were performed. (author)

  9. 40 CFR 1065.675 - CLD quench verification calculations.

    Science.gov (United States)

    2010-07-01

    ... verification calculations. Perform CLD quench-check calculations as follows: (a) Perform a CLD analyzer quench... water content in combustion air, fuel combustion products, and dilution air (if applicable). If you... the maximum expected CO2 content in fuel combustion products and dilution air. (d) Calculate quench...

  10. Static and dynamic quenching of luminescent species in polymer media.

    Science.gov (United States)

    Hartmann, P; Leiner, M J; Lippitsch, M E

    1994-12-01

    A method developed for quantitative determination of static and dynamic contributions to luminescence quenching is applied to Ru(II) complexes in polymer matrices (silica gel and polystyrene), quenched by oxygen. This method is based on both intensity and lifetime quenching experiments. The curvature of intensity Stern-Volmer plots is related to the results.

  11. First experience with the new coupling loss induced quench system

    NARCIS (Netherlands)

    Ravaioli, E.; Datskov, V.I.; Dudarev, A.V.; Kirby, G.; Sperin, K.A.; Kate, ten H.H.J.; Verweij, A.P.

    2014-01-01

    New-generation high-field superconducting magnets pose a challenge relating to the protection of the coil winding pack in the case of a quench. The high stored energy per unit volume calls for a very efficient quench detection and fast quench propagation in order to avoid damage due to overheating. A

  12. Collapse and Revival in Holographic Quenches

    CERN Document Server

    da Silva, Emilia; Mas, Javier; Serantes, Alexandre

    2014-01-01

    We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals.

  13. Quench from Mott Insulator to Superfluid

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Wojciech H. [Los Alamos National Laboratory; Dziarmaga, Jacek [Instytut Fizyki Uniwersytetu Jagiello´nskiego; Tylutki, Marek [Instytut Fizyki Uniwersytetu Jagiello´nskiego

    2012-06-01

    We study a linear ramp of the nearest-neighbor tunneling rate in the Bose-Hubbard model driving the system from the Mott insulator state into the superfluid phase. We employ the truncated Wigner approximation to simulate linear quenches of a uniform system in 1...3 dimensions, and in a harmonic trap in 3 dimensions. In all these setups the excitation energy decays like one over third root of the quench time. The -1/3 scaling is explained by an impulse-adiabatic approximation - a variant of the Kibble-Zurek mechanism - describing a crossover from non-adiabatic to adiabatic evolution when the system begins to keep pace with the increasing tunneling rate.

  14. Energy upgrade as regards quench performance

    Energy Technology Data Exchange (ETDEWEB)

    MacKay, W.W.; Tepikian, S.

    2011-01-01

    Since the cross section for W production increases rapidly with energy, we consider the possibility of increasing the collision energy of polarized protons at RHIC. The limits of present hardware are examined with a particular emphasis on the quench training performance of magnets. Ignoring the limits of the DX magnets, the short-sample currents for the main arc (8 cm) dipoles could allow an increase of more than 30%, however we estimate 400 to 500 training quenches for the just 8 cm dipoles to reach this level. We propose that a 10% increase in energy might be achieved with the present hardware configuration. Raising the beam energy to 275 GeV ({radical}s = 550 GeV) should increase the W production rate by almost 50% from the 250 GeV level for the same optics with identical {beta}*'s at the collision points.

  15. Quench dynamics of the anisotropic Heisenberg model.

    Science.gov (United States)

    Liu, Wenshuo; Andrei, Natan

    2014-06-27

    We develop an analytical approach for the study of the quench dynamics of the anisotropic Heisenberg model (XXZ model) on the infinite line. We present the exact time-dependent wave functions after a quench in an integral form for any initial state and for any anisotropy Δ by means of a generalized Yudson contour representation. We calculate the evolution of several observables from two particular initial states: starting from a local Néel state we calculate the time evolution of the antiferromagnetic order parameter-staggered magnetization; starting from a state with consecutive flipped spins (1) we calculate the evolution of the local magnetization and express it in terms of the propagation of magnons and bound state excitations, and (2) we predict the evolution of the induced spin currents. These predictions can be confronted with experiments in ultracold gases in optical lattices. We also show how the "string" solutions of Bethe ansatz equations emerge naturally from the contour approach.

  16. Collapse and revival in holographic quenches

    Science.gov (United States)

    da Silva, Emilia; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2015-04-01

    We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals.

  17. Design of continuous walking beam furnaces for quench and tempering of oil country tubulars

    Energy Technology Data Exchange (ETDEWEB)

    Casana, A.; Stabile, V.

    1982-09-01

    Explains how, because users of oil pipes demand higher steel qualities, with pipe uniformly treated inside and out, heat treatment plants have undergone a steady technological improvement. The trend of increased product quality has led to a tendency to interrelate the product both with the process and the production facility. The furnaces and quench and tempering processes are of particular importance in the overall production cycle for tube. Describes and illustrates some technical solutions realized in quenching and tempering walking beam furnaces. Furnace dimensions depend on the total heating and soaking time for the products. Presents diagram depicting refractory materials used for lining the walls and hearth of the walking beam furnaces.

  18. The impact of galactic properties and environment on the quenching of central and satellite galaxies: a comparison between SDSS, Illustris and L-Galaxies

    Science.gov (United States)

    Bluck, Asa F. L.; Mendel, J. Trevor; Ellison, Sara L.; Patton, David R.; Simard, Luc; Henriques, Bruno M. B.; Torrey, Paul; Teimoorinia, Hossen; Moreno, Jorge; Starkenburg, Else

    2016-11-01

    We quantify the impact that a variety of galactic and environmental properties have on the quenching of star formation. We collate a sample of ˜400 000 central and ˜100 000 satellite galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Specifically, we consider central velocity dispersion (σc), stellar, halo, bulge and disc mass, local density, bulge-to-total ratio, groupcentric distance and galaxy-halo mass ratio. We develop and apply a new statistical technique to quantify the impact on the quenched fraction (fQuench) of varying one parameter, while keeping the remaining parameters fixed. For centrals, we find that the fQuench-σc relationship is tighter and steeper than for any other variable considered. We compare to the Illustris hydrodynamical simulation and the Munich semi-analytic model (L-Galaxies), finding that our results for centrals are qualitatively consistent with their predictions for quenching via radio-mode AGN feedback, hinting at the viability of this process in explaining our observational trends. However, we also find evidence that quenching in L-Galaxies is too efficient and quenching in Illustris is not efficient enough, compared to observations. For satellites, we find strong evidence that environment affects their quenched fraction at fixed central velocity dispersion, particularly at lower masses. At higher masses, satellites behave identically to centrals in their quenching. Of the environmental parameters considered, local density affects the quenched fraction of satellites the most at fixed central velocity dispersion.

  19. Reductive fluorescence quenching of DMP with aniline

    Energy Technology Data Exchange (ETDEWEB)

    Asha Jhonsi, M. [B.S. Abdur Rahman University, Vandalur, Chennai 600048, Tamil Nadu (India); Kathiravan, A., E-mail: akathir23@hotmail.com [National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai 600113, Tamil Nadu (India)

    2014-01-15

    The photoinduced electron transfer (PET) between 8-(4-methoxyphenyl)-3,5-di[(E)-1-(4-methoxyphenyl)methylidene]-1,2,3,5,6, 7-hexahydrodicyclopenta[b,e]pyridine (DMP) and aniline is studied in acetonitrile medium by using steady state and time resolved absorption and fluorescence spectroscopic methods. Bimolecular quenching rate constants (k{sub q}) were calculated from the obtained linear Stern–Volmer plots from both steady state and time resolved measurements. The rate constant (k{sub q}) for PET between DMP and aniline is 1.4×10{sup 10} M{sup −1} s{sup −1}, which is in diffusion control limit. The free energy change (ΔG{sup 0}) has been evaluated by using Rehm–Weller equation for the evidence of electron transfer from aniline to DMP. Direct evidence for the electron transfer reaction in the present system has been obtained by characterizing the aniline cation radical using nanosecond time resolved absorption measurements in the visible region. Further, this quenching mechanism is attributed to be reductive in nature i.e. electron transfer occurs from ground state aniline to excited DMP. This is the first example of reductive fluorescence quenching of DMP with aniline in acetonitrile ever known. -- Highlights: • Photoinduced electron transfer between DMP and aniline using time resolved absorption and fluorescence spectroscopy has been investigated. • Reductive quenching behavior was observed. • Direct evidence for the ET reaction in the present system has been obtained by characterizing the aniline cation radical.

  20. Quenching of the Deuteron in Flight

    CERN Document Server

    Dillig, M

    2006-01-01

    We investigate the Lorentz contraction of a deuteron in flight. Our starting point is the Blankenbecler-Sugar projection of the Bethe-Salpeter equation to a 3-dimensional quasi potential equation, wqhich we apply for the deuteron bound in an harmonic oscillator potential (for an analytical result) and by the Bonn NN potential for a more realistic estimate. We find substantial quenching with increasing external momenta and a significant modification of the high momentum spectrum of the deuteron.

  1. Successful magnet quench test for CAST.

    CERN Multimedia

    Brice Maximilien

    2002-01-01

    The CERN Axion Solar Telescope (CAST) consists of a prototype LHC dipole magnet with photon detectors at each end. It searches for very weakly interacting neutral particles called axions, which should originate in the core of the Sun. The telescope, located at Point 8, can move vertically within its wheeled platform, which travels horizontally along tracks in the floor. In this way, the telescope can view the Sun at sunrise through one end and at sunset through the other end. It has been cooled down to below 1.8 K and reached ~95% of its final magnetic field of 9 tesla before a quench was induced to test the whole cryogenic system under such conditions. The cryogenic system responded as expected to the magnet quench and CAST is now ready to start its three-year search for solar axions. Photos 01 & 02 : Members of the LHC cryogenics team pose in front of the axion telescope on the day of the first quench test, together with some of the CAST collaboration.

  2. MgB2掺杂纳米碳的淬熄实验过程研究%A Study on the Experimental Process of the Quenching of MgB2 Doped with Nanocarbon

    Institute of Scientific and Technical Information of China (English)

    何祖明; 冯旺军; 江兴方; 唐斌

    2016-01-01

    在锥形石墨模具内成功淬熄了 MgB2掺杂纳米碳的实验,用 X 射线衍射仪(XRD)和扫描电子显微镜(SEM)对实验中不同反应区域试样的微观结构进行了分析。结果表明:520~650℃时, Mg和B颗粒接触表面发生了渗透方式的固-固反应,Mg 的表面层初次形成了 MgB2晶核;温度高于650℃时,发生剧烈的液-固放热反应生成了MgB2,并有少量MgB2分解形成MgB4和Mg,同时,有部分碳原子进入到MgB2晶格,替代B的位置,引起晶格畸变,从而产生有效的钉扎中心,并且部分纳米碳以杂相的形式存在于MgB2的晶界中,起到了细化晶粒的作用,增强了晶粒的连接性。%The experiment in quenching MgB2 doped with Nanocarbon was successfully conducted in the conical graphite mould.X ray diffraction (XRD)and scanning electron microscopy (SEM) were used to analyze the microstructure of the samples in different reaction phases.The results indicated that solid-solid reaction happened on the contact surface of magnesium element and bo-ron element in the osmotic way at 520 ~ 650 ℃,and the MgB2 crystal nuclei were formed on the surface layer of magnesium element,and that when the temperature was higher than 650 ℃,vio-lent liquid-solid exothermic reaction occurred,MgB2 was generated,but a small amount of syn-thesized MgB2 was decomposed to form MgB4 and Mg.At the same time,some of the carbon at-oms permeated into the MgB2 crystal lattice,partially replacing B atoms,which caused the lattice distortion and formed an effective pinning center.A small amount of nanocarbon in the form of mixed phase emerged in the grain boundary of MgB2 ,which played an important role in refining the grain size and enhanced the connectivity of grains.

  3. O2(a1Δ) Quenching In The O/O2/O3 System

    Science.gov (United States)

    Azyazov, V. N.; Mikheyev, P. A.; Postell, D.; Heaven, M. C.

    2010-10-01

    The development of discharge singlet oxygen generators (DSOG's) that can operate at high pressures is required for the power scaling of the discharge oxygen iodine laser. In order to achieve efficient high-pressure DSOG operation it is important to understand the mechanisms by which singlet oxygen (O2(a1Δ)) is quenched in these devices. It has been proposed that three-body deactivation processes of the type O2(a1Δ)+O+M→2O2+M provide significant energy loss channels. To further explore these reactions the physical and reactive quenching of O2(a1Δ) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a1Δ) quenching were followed by observing the 1268 nm fluorescence of the O2a1Δ-X3∑ transition. Fast quenching of O2(a1Δ) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

  4. Advanced active quenching circuits for single-photon avalanche photodiodes

    Science.gov (United States)

    Stipčević, M.; Christensen, B. G.; Kwiat, P. G.; Gauthier, D. J.

    2016-05-01

    Commercial photon-counting modules, often based on actively quenched solid-state avalanche photodiode sensors, are used in wide variety of applications. Manufacturers characterize their detectors by specifying a small set of parameters, such as detection efficiency, dead time, dark counts rate, afterpulsing probability and single photon arrival time resolution (jitter), however they usually do not specify the conditions under which these parameters are constant or present a sufficient description. In this work, we present an in-depth analysis of the active quenching process and identify intrinsic limitations and engineering challenges. Based on that, we investigate the range of validity of the typical parameters used by two commercial detectors. We identify an additional set of imperfections that must be specified in order to sufficiently characterize the behavior of single-photon counting detectors in realistic applications. The additional imperfections include rate-dependence of the dead time, jitter, detection delay shift, and "twilighting." Also, the temporal distribution of afterpulsing and various artifacts of the electronics are important. We find that these additional non-ideal behaviors can lead to unexpected effects or strong deterioration of the system's performance. Specifically, we discuss implications of these new findings in a few applications in which single-photon detectors play a major role: the security of a quantum cryptographic protocol, the quality of single-photon-based random number generators and a few other applications. Finally, we describe an example of an optimized avalanche quenching circuit for a high-rate quantum key distribution system based on time-bin entangled photons.

  5. The Mass Dependence of Dwarf Satellite Galaxy Quenching

    Science.gov (United States)

    Slater, Colin T.; Bell, Eric F.

    2014-09-01

    We combine observations of the Local Group with data from the NASA-Sloan Atlas to show the variation in the quenched fraction of satellite galaxies from low-mass dwarf spheroidals and dwarf irregulars to more massive dwarfs similar to the Magellanic Clouds. While almost all of the low-mass (M sstarf 5 Gyr ago. We also characterize how the susceptibility of dwarfs to ram pressure must vary as a function of mass if it is to account for the change in quenched fractions. Though neither model predicts the quenching effectiveness a priori, this modeling illustrates the physical requirements that the observed quenched fractions place on possible quenching mechanisms.

  6. Application of best estimate approach for modelling of QUENCH-03 and QUENCH-06 experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kaliatka, Tadas; Kaliatka, Algirdas; Vileiniskis, Virginijus [Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos (Lithuania)

    2016-04-15

    One of the important severe accident management measures in the Light Water Reactors is water injection to the reactor core. The related phenomena are investigated by performing experiments and computer simulations. One of the most widely known is the QUENCH test-program. A number of analyses on QUENCH tests have also been performed by different computer codes for code validation and improvements. Unfortunately, any deterministic computer simulation is not free from the uncertainties. To receive the realistic calculation results, the best estimate computer codes should be used for the calculation with combination of uncertainty and sensitivity analysis of calculation results. In this article, the QUENCH-03 and QUENCH-06 experiments are modelled using ASTEC and RELAP/SCDAPSIM codes. For the uncertainty and sensitivity analysis, SUSA3.5 and SUNSET tools were used. The article demonstrates that applying the best estimate approach, it is possible to develop basic QUENCH input deck and to develop the two sets of input parameters, covering maximal and minimal ranges of uncertainties. These allow simulating different (but with the same nature) tests, receiving calculation results with the evaluated range of uncertainties.

  7. Quench propagation and protection analysis of the ATLAS Toroids

    CERN Document Server

    Dudarev, A; ten Kate, H H J; Baynham, D Elwyn; Courthold, M J D; Lesmond, C

    2000-01-01

    The ATLAS superconducting magnet system consists of the Barrel Toroid, two End Cap Toroids and the Central Solenoid. However, the Toroids of eight coils each are magnetically separate systems to the Central Solenoid. The Toroids are electrically connected in series and energized by a single power supply. The quench protection system is based on the use of relatively small external dump resistances in combination with quench-heaters activated after a quench event detection to initiate the internal dump of stored energy in all the coils. A rather strong quench-back effect due to eddy-currents in the coil casings at the transport current decay is beneficial for the quench protection efficiency in the event of heater failures. The quench behaviour of the ATLAS Toroids was computer simulated for normal operation of the quench protection system and its complete non-operation (failure) mode. (3 refs).

  8. Minimum Quench Energy and Early Quench Development in NbTi Superconducting Strands

    CERN Document Server

    Breschi, M; Boselli, M; Bottura, Luca; Devred, Arnaud; Ribani, P L; Trillaud, F

    2007-01-01

    The stability of superconducting wires is a crucial task in the design of safe and reliable superconducting magnets. These magnets are prone to premature quenches due to local releases of energy. In order to simulate these energy disturbances, various heater technologies have been developed, such as coated tips, graphite pastes, and inductive coils. The experiments studied in the present work have been performed using a single-mode diode laser with an optical fiber to illuminate the superconducting strand surface. Minimum quench energies and voltage traces at different magnetic flux densities and transport currents have been measured on an LHC-type, Cu/NbTi wire bathed in pool boiling helium I. This paper deals with the numerical analysis of the experimental data. In particular, a coupled electromagnetic and thermal model has been developed to study quench development and propagation, focusing on the influence of heat exchange with liquid helium.

  9. Photochemical reflectance index as a mean of monitoring early water stress

    NARCIS (Netherlands)

    Sarlikioti, V.; Driever, S.M.; Marcelis, L.F.M.

    2010-01-01

    Water stress in plants affects a number of physiological processes such as photosynthetic rate, stomatal conductance as well as the operating efficiency of photosystem II (PSII) and non-photochemical quenching (NPQ). Photochemical reflectance index (PRI) is reported to be sensitive to changes in xan

  10. Formation of monatomic metallic glasses through ultrafast liquid quenching.

    Science.gov (United States)

    Zhong, Li; Wang, Jiangwei; Sheng, Hongwei; Zhang, Ze; Mao, Scott X

    2014-08-14

    It has long been conjectured that any metallic liquid can be vitrified into a glassy state provided that the cooling rate is sufficiently high. Experimentally, however, vitrification of single-element metallic liquids is notoriously difficult. True laboratory demonstration of the formation of monatomic metallic glass has been lacking. Here we report an experimental approach to the vitrification of monatomic metallic liquids by achieving an unprecedentedly high liquid-quenching rate of 10(14) K s(-1). Under such a high cooling rate, melts of pure refractory body-centred cubic (bcc) metals, such as liquid tantalum and vanadium, are successfully vitrified to form metallic glasses suitable for property interrogations. Combining in situ transmission electron microscopy observation and atoms-to-continuum modelling, we investigated the formation condition and thermal stability of the monatomic metallic glasses as obtained. The availability of monatomic metallic glasses, being the simplest glass formers, offers unique possibilities for studying the structure and property relationships of glasses. Our technique also shows great control over the reversible vitrification-crystallization processes, suggesting its potential in micro-electromechanical applications. The ultrahigh cooling rate, approaching the highest liquid-quenching rate attainable in the experiment, makes it possible to explore the fast kinetics and structural behaviour of supercooled metallic liquids within the nanosecond to picosecond regimes.

  11. Analysis of heat transfer during quenching of a gear blank

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Sahai, V

    1999-03-01

    This paper presents experimental and numerical results for the quench of a gear blank in agitated and stagnant oil. Heat transfer within the gear blank is analyzed with a whole domain-optimizer technique inverse solution method, to calculate the time history at every point in the gear blank. The development of this procedure represents the first stage in an overall analysis of the quench process that will later include material phase transformations and deformation. The paper presents ten variations in setting up the inverse problem, to analyze which combination of independent variables and decision variables results in the best match between experimental and numerical results. The results indicate that dividing the boundary of the gear blank into four zones and assigning a fixed heat transfer coefficient or heat flux to each zone yields an average RMS error (average difference between experimental and numerical results) of the order of 40 K. This error can be reduced by either increasing the number of zones, by reducing the number of thermocouples being matched, or by allowing the heat transfer or heat flux to vary within the zones. Of these possibilities, variation of heat transfer within the zones gives the best improvement in the quality of the match for the amount of extra effort required to run the problem.

  12. Star Formation and Environmental Quenching of GEEC2 Group Galaxies at z~1

    CERN Document Server

    Mok, Angus; McGee, Sean L; Wilman, David J; Finoguenov, Alexis; Tanaka, Masayuki; Bower, Richard G; Hou, Annie; Mulchaey, John S; Parker, Laura C

    2013-01-01

    We present new analysis from the GEEC2 spectroscopic survey of galaxy groups at $0.8quenching is the primary process in the transition from the star-forming to the quiescent state. To model the environmental quenching scenario, we have tested the use of different exponential quenching timescales and delays between satellite accretion and the onset of quenching. We find that with no delay, the quenching timescale needs to be long in order to match the observed quiescent fraction, but then this model produces too many intermediate galaxies. Fixing a delay time of 3 Gyr, as suggested from the local universe, produces too few quiescent galaxies. The observed fractions are be...

  13. A Hybrid Strong/Weak Coupling Approach to Jet Quenching

    CERN Document Server

    Casalderrey-Solana, Jorge; Milhano, José Guilherme; Pablos, Daniel; Rajagopal, Krishna

    2014-01-01

    We propose and explore a new hybrid approach to jet quenching in a strongly coupled medium. The basis of this phenomenological approach is to treat physics processes at different energy scales differently. The high-$Q^2$ processes associated with the QCD evolution of the jet from production as a single hard parton through its fragmentation, up to but not including hadronization, are treated perturbatively. The interactions between the partons in the shower and the deconfined matter within which they find themselves lead to energy loss. The momentum scales associated with the medium (of the order of the temperature) and with typical interactions between partons in the shower and the medium are sufficiently soft that strongly coupled physics plays an important role in energy loss. We model these interactions using qualitative insights from holographic calculations of the energy loss of energetic light quarks and gluons in a strongly coupled plasma, obtained via gauge/gravity duality. We embed this hybrid model ...

  14. Effects of thermal quenching on the breakup of pyroclasts

    Science.gov (United States)

    Patel, A.; Manga, M.; Carey, R. J.; Degruyter, W.; Dufek, J.

    2012-12-01

    It is often assumed that magma fragments when it contacts water. Obsidian chips and glass spheres crack when quenched. Vesicular pyroclasts are made of similar glass, so thermal quenching may cause them to break more easily. We performed a set of experiments on air fall pumice from Medicine Lake, California. Density and texture of similar samples are described in Manga et al., Bull Volc 2010. We made "quenched" samples by heating natural pyroclasts to 600 °C, quenching them in water at 21 °C, drying them at 105 °C, and then cooling them to room temperature. We compare these samples with untreated air fall pumice from the same deposit, hereafter referred to as "regular" pumice. We tested whether quenched pumice would 1) shatter more easily in collisions and 2) abrade faster. Our collision experiment methods are described in Dufek et al., Nature Geoscience 2012. Our abrasion experiment methods are described in Manga et al., Bull Volc 2010. We also tested whether individual clasts lose mass upon quenching and whether they increase in effective wet density. Effective wet density is defined as underwater density of a clast when water occupies part of the pore space. Effective wet density, measured as a function of time after immersion, indicates the volume fraction of the pore space that becomes occupied by water. We compare effective wet density of individual clasts pre-quenching with effective wet density after having been quenched, thoroughly dried and then cooled to room temperature. An increase in effective wet density would suggest that bubble walls had been damaged during quenching, allowing water to occupy the pore space faster. We also compare pre-quenching and post-quenching textures using X-Ray Tomography (XRT) and SEM images. Results from collision experiments show no obvious difference between quenched pumice and regular pumice. Quenched pumice abraded more quickly than regular pumice. We find that 1 to 2 % of mass was lost during quenching. Effective

  15. Finite Element Analysis of Residual Stress and Distortion in an Eccentric Ring Induced by Quenching

    Institute of Scientific and Technical Information of China (English)

    YAOXin; ZHULi-hua; LIM.Victor

    2004-01-01

    The residual stresses and distortion induced by quenching in an eccentric ring were investigated in this study with finite element method. The ring was made of AISI 52100 steel. A fully coupled 3D temperature-displacement analysis was performed to simulate heat transfer, phase transformations, and mechanical stresses and strains during the heating and subsequent quenching processes. Commercial FEA package ABAQUS/Standard 6.4 was used for the analyses along with user subroutines developed by the authors to model the thermal and mechanical constitutive behavior. The simulation results show that transformation plasticity plays an important role on the residual stress distribution.

  16. Effect of quenching techniques on the mechanical properties of low carbon structural steel

    Directory of Open Access Journals (Sweden)

    K. Miernik

    2010-07-01

    Full Text Available The paper presents the results of the impact of incomplete quenching technique on the mechanical properties of low carbon structural steel.Significant influence of the heating method to the α + γ field was observed on the strength and plasticity after hardening process. The best combination of mechanical properties was obtained for the 3th technique consisting of pre-heating the material to the austenite field, next cooling to the appropriate temperature in the α + γ and hardening from that dual phase region. The high level of toughness with relatively high strength were observed, compared to the properties obtained for the two other ways to quench annealing (incomplete hardening.

  17. Research into Grinding Hardening of Microalloyed Non-quenched and Tempered Steel

    Institute of Scientific and Technical Information of China (English)

    HAN Zheng-tong; ZHANG Ning-ju; GAO Ding; YANG Gang

    2007-01-01

    Grinding hardening is a new technology of hardening steel piece surfaces with grinding heat generated in the grinding process instead of with a high or medium frequency induction heating method, which can effectively integrate grinding and surface hardening. Experimental studies were carried out on grinding hardening of non-quenched and tempered steel. Through grinding experiments with variable depths of cut and feeding rate, the variation in the depth of the hardening layer was studied and the microstructure of the hardening zone of the test pieces was subsequently analyzed. In the end, the hardening effect of non-quenched and tempered steel was compared with that of 40Cr steel, which revealed the superiority of non-quenched and tempered steel in grinding hardening technology.

  18. Evaluation of Enoyl-Acyl Carrier Protein Reductase Inhibitors as Pseudomonas aeruginosa Quorum-Quenching Reagents

    Directory of Open Access Journals (Sweden)

    Søren Molin

    2010-02-01

    Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen which is responsible for a wide range of infections. Production of virulence factors and biofilm formation by P. aeruginosa are partly regulated by cell-to-cell communication quorum-sensing systems. Identification of quorum-quenching reagents which block the quorum-sensing process can facilitate development of novel treatment strategies for P. aeruginosa infections. We have used molecular dynamics simulation and experimental studies to elucidate the efficiencies of two potential quorum-quenching reagents, triclosan and green tea epigallocatechin gallate (EGCG, which both function as inhibitors of the enoyl-acyl carrier protein (ACP reductase (ENR from the bacterial type II fatty acid synthesis pathway. Our studies suggest that EGCG has a higher binding affinity towards ENR of P. aeruginosa and is an efficient quorum-quenching reagent. EGCG treatment was further shown to be able to attenuate the production of virulence factors and biofilm formation of P. aeruginosa.

  19. Development of Industrially Produced Composite Quench Heaters for the LHC Superconducting Lattice Magnets

    CERN Document Server

    Szeless, Balázs; Calvone, F

    1996-01-01

    The quench heaters are vital elements for the protection of the LHC superconducting lattice magnets in the case of resistive transitions of the conductor. The basic concept of magnet protection and technical solutions are briefly presented. The quench heater consists of partially copper clad stainless steel strips sandwiched in between electric insulating carrier foils with electrical and mechanical properties such as to withstand high voltages, low temperatures, pressures and ionizing radiation. Testing of some commercial available electric insulation foils, polyimide (PI), polyetheretherketon (PEEK) and polyarylate (PA) and combinations of adhesive systems which are suitable for industrial processing are described. Possible industrial methods for series production for some 80 km of these composite quench heaters are indicated.

  20. Quenched Free Energy and Large Deviations for Random Walks in Random Potentials

    CERN Document Server

    Rassoul-Agha, Firas; Yilmaz, Atilla

    2011-01-01

    We study quenched distributions on random walks in a random potential on integer lattices of arbitrary dimension and with an arbitrary finite set of admissible steps. The potential can be unbounded and can depend on a few steps of the walk. Directed, undirected and stretched polymers, as well as random walk in random environment, are covered. The restriction needed is on the moment of the potential, in relation to the degree of mixing of the ergodic environment. We derive two variational formulas for the limiting quenched free energy and prove a process-level quenched large deviation principle for the empirical measure. As a corollary we obtain LDPs for types of random walk in random environment not covered by earlier results.

  1. Quenching simulation of steel grinding balls

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Hernandez, O.; Reyes, L. A.; Camurri, C.; Carrasco, C.; Garza-Monte-de-Oca, F.; Colas, R.

    2015-07-01

    The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses. (Author)

  2. Jet Quenching Measurements with ATLAS at LHC

    CERN Document Server

    Brooks, W K; The ATLAS collaboration

    2009-01-01

    A broad program of measurements is planned for heavy ion collisions in ATLAS. With up to a factor of 30 increase in collision energy compared to existing data, significant new insights are anticipated to be obtained with the first data measured. Global features of the LHC collisions will be accessible with the early data and will set the stage for the precision measurements to follow. ATLAS is particularly well suited for exploration of "jet quenching," the extinction of energetic jets in the hot dense medium. Observations of heavy quark jet suppression will be possible with unprecedented energy reach and statistical precision, potentially yielding new insights into the basic mechanisms involved.

  3. $B_{K}$ from quenched overlap QCD

    CERN Document Server

    Garron, N; Hölbling, C; Lellouch, L P; Rebbi, C

    2003-01-01

    We present an exploratory calculation of the standard model Delta S=2 matrix element relevant for indirect CP violation in K -> pi pi decays. The computation is performed with overlap fermions in the quenched approximation at beta=6.0 on a 16^3x32 lattice. The resulting bare matrix element is renormalized non-perturbatively. Our preliminary result is B_K^{NDR}(2 GeV)=0.61(7), where the error does not yet include an estimate of systematic uncertainties.

  4. Evaluation of Enoyl-Acyl Carrier Protein Reductase Inhibitors as Pseudomonas aeruginosa Quorum-Quenching Reagents

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Sternberg, Claus

    2010-01-01

    which block the quorum-sensing process can facilitate development of novel treatment strategies for P. aeruginosa infections. We have used molecular dynamics simulation and experimental studies to elucidate the efficiencies of two potential quorum-quenching reagents, triclosan and green tea...

  5. Evolution of density profiles in high-z galaxies: compaction and quenching inside-out

    Science.gov (United States)

    Tacchella, Sandro; Dekel, Avishai; Carollo, C. Marcella; Ceverino, Daniel; DeGraf, Colin; Lapiner, Sharon; Mandelker, Nir; Primack, Joel R.

    2016-05-01

    Using cosmological simulations, we address the interplay between structure and star formation in high-redshift galaxies via the evolution of surface density profiles. Our sample consists of 26 galaxies evolving in the redshift range z = 7 - 1, spanning the stellar mass range (0.2-6.4) × 1010 M⊙ at z = 2. We recover the main trends by stacking the profiles in accordance to their evolution phases. Following a wet compaction event that typically occurs when the stellar mass is ˜109.5 M⊙ at z ˜ 2-4, the gas develops a cusp inside the effective radius, associated with a peak in star formation rate (SFR). The SFR peak and the associated feedback, in the absence of further gas inflow to the centre, marks the onset of gas depletion from the central 1 kpc, leading to quenching of the central SFR. An extended, star-forming ring that forms by fresh gas during the central quenching process shows as a rising specific SFR (sSFR) profile, which is interpreted as inside-out quenching. Before quenching, the stellar density profile grows self-similarly, maintaining its log-log shape because the sSFR is similar at all radii. During the quenching process, the stellar density saturates to a constant value, especially in the inner 1 kpc. The stellar mass and SFR profiles deduced from observations show very similar shapes, consistent with the scenario of wet compaction leading to inside-out quenching and the subsequent saturation of a dense stellar core. We predict a cuspy gas profile during the blue nugget phase, and a gas-depleted core, sometimes surrounded by a ring, in the post-blue nugget phase.

  6. Effect of Bath Temperature on Cooling Performance of Molten Eutectic NaNO3-KNO3 Quench Medium for Martempering of Steels

    Science.gov (United States)

    Pranesh Rao, K. M.; Narayan Prabhu, K.

    2017-10-01

    Martempering is an industrial heat treatment process that requires a quench bath that can operate without undergoing degradation in the temperature range of 423 K to 873 K (150 °C to 600 °C). The quench bath is expected to cool the steel part from the austenizing temperature to quench bath temperature rapidly and uniformly. Molten eutectic NaNO3-KNO3 mixture has been widely used in industry to martemper steel parts. In the present work, the effect of quench bath temperature on the cooling performance of a molten eutectic NaNO3-KNO3 mixture has been studied. An Inconel ASTM D-6200 probe was heated to 1133 K (860 °C) and subsequently quenched in the quench bath maintained at different temperatures. Spatially dependent transient heat flux at the metal-quenchant interface for each bath temperature was calculated using inverse heat conduction technique. Heat transfer occurred only in two stages, namely, nucleate boiling and convective cooling. The mean peak heat flux ( q max) decreased with increase in quench bath temperature, whereas the mean surface temperature corresponding to q max and mean surface temperature at the start of convective cooling stage increased with increase in quench bath temperature. The variation in normalized cooling parameter t 85 along the length of the probe increased with increase in quench bath temperature.

  7. Heat transfer model for quenching by submerging

    Energy Technology Data Exchange (ETDEWEB)

    Passarella, D N; Varas, F [Departamento de Matematica Aplicada II, E.T.S. de Ing. de Telecomunicacion, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain); MartIn, E B, E-mail: diego@dma.uvigo.es, E-mail: fvaras@uvigo.es, E-mail: emortega@uvigo.es [Area de Mecanica de Fluidos, E.T.S. de Ing. Industriales, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain)

    2011-05-01

    In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.

  8. Quench thresholds in operational superconducting magnets

    Energy Technology Data Exchange (ETDEWEB)

    Allinger, J; Danby, G; Foelsche, H; Jackson, J; Lowenstein, D; Prodell, A; Weng, W

    1978-01-01

    Superconducting magnets exposed to intense primary proton beams in high energy physics applications are subject to potentially extreme heat deposition. The beam power density, its duration and spatial distribution, the current density in the superconductor and, potentially, in the normal metal substrate, as well as the construction and cooling details of the magnet, are all relevant parameters. An extension of some earlier work is discussed in which 28.5 GeV/c proton beams with up to 50 k joules of energy were targeted upstream from a 4 m long, 4 T dipole magnet used to deflect the protons through an angle of 8/sup 0/. Quench thresholds much greater than the enthalpy limit of the magnet materials were observed. In the beam exposure experiment described, intense beams of 1.5 GeV/c protons have been deflected directly into the magnet coil at relatively steep angles of incidence. The magnet quench threshold was studied by varying the beam currents and beam sizes.

  9. Quorum Quenching Revisited—From Signal Decays to Signalling Confusion

    Directory of Open Access Journals (Sweden)

    Kok-Gan Chan

    2012-04-01

    Full Text Available In a polymicrobial community, while some bacteria are communicating with neighboring cells (quorum sensing, others are interrupting the communication (quorum quenching, thus creating a constant arms race between intercellular communication. In the past decade, numerous quorum quenching enzymes have been found and initially thought to inactivate the signalling molecules. Though this is widely accepted, the actual roles of these quorum quenching enzymes are now being uncovered. Recent evidence extends the role of quorum quenching to detoxification or metabolism of signalling molecules as food and energy source; this includes “signalling confusion”, a term coined in this paper to refer to the phenomenon of non-destructive modification of signalling molecules. While quorum quenching has been explored as a novel anti-infective therapy targeting, quorum sensing evidence begins to show the development of resistance against quorum quenching.

  10. System and method for quench protection of a superconductor

    Science.gov (United States)

    Huang, Xianrui; Sivasubramaniam, Kiruba Haran; Bray, James William; Ryan, David Thomas

    2008-03-11

    A system and method for protecting a superconductor from a quench condition. A quench protection system is provided to protect the superconductor from damage due to a quench condition. The quench protection system comprises a voltage detector operable to detect voltage across the superconductor. The system also comprises a frequency filter coupled to the voltage detector. The frequency filter is operable to couple voltage signals to a control circuit that are representative of a rise in superconductor voltage caused by a quench condition and to block voltage signals that are not. The system is operable to detect whether a quench condition exists in the superconductor based on the voltage signal received via the frequency filter and to initiate a protective action in response.

  11. Bridging global and local quantum quenches in conformal field theories

    CERN Document Server

    Wen, Xueda

    2016-01-01

    Entanglement evolutions after a global quantum quench and a local quantum quench in 1+1 dimensional conformal field theories (CFTs) show qualitatively different behaviors, and are studied within two different setups. In this work, we bridge global and local quantum quenches in (1+1)-d CFTs in the same setup, by studying the entanglement evolution from a specific inhomogeneous initial state. By utilizing conformal mappings, this inhomogeneous quantum quench is analytically solvable. It is found that the entanglement evolution shows a global quantum quench feature in the short time limit, and a local quantum quench feature in the long time limit. The same features are observed in single-point correlation functions of primary fields. We provide a clear physical picture for the underlying reason.

  12. Variation of Quench Propagation Velocities in YBCO Cables

    CERN Document Server

    Härö, E.; Stenvall, A.; 10.1007/s10948-015-2976-y

    2015-01-01

    changes during the quench. Due to the large temperature margin between the operation and the current sharing temperatures, the normal zone does not propagate with the temperature front. This means that the temperature will rise in a considerably larger volume when compared to the quenched volume. Thus, the evolution of the temperature distribution below current sharing temperature Tcs after the quench onset affects the normal zone propagation velocity in HTS more than in LTS coils. This can be seen as an acceleration of the quench propagation velocities while the quench evolves when margin to Tcs is high. In this paper we scrutinize quench propagation in a stack of YBCO cables with an in-house finite element method software which solves the heat diffusion equation. We compute the longitudinal and transverse normal zone propagation velocities at various distances from the hot spot to demonstrate the distance-variation...

  13. Holographic study on the jet quenching parameter in anisotropic systems

    CERN Document Server

    Wang, Luying

    2016-01-01

    We first calculate the jet quenching parameter of an anisotropic plasma with a U(1) chemical potential via the AdS/CFT duality. The effects of charge, anisotropy parameter and quark motion direction on the jet quenching parameter are investigated. We then discuss the situation of anisotropic black brane in the IR region. We study both the jet quenching parameters along the longitudinal direction and transverse plane.

  14. Holographic study of the jet quenching parameter in anisotropic systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Luying [Shanghai University, Department of Physics, Shanghai (China); Wu, Shang-Yu [National Chiao Tung University, Department of Electrophysics, Hsinchu (China)

    2016-11-15

    We first calculate the jet quenching parameter of an anisotropic plasma with a U(1) chemical potential via AdS/CFT duality. The effects of charge, anisotropy parameter, and quark motion direction on the jet quenching parameter are investigated. We then discuss the situation of an anisotropic black brane in the IR region. We study both the jet quenching parameters along the longitudinal direction and the transverse plane. (orig.)

  15. Quenching of porous silicon photoluminescence by deposition of metal adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Andsager, D.; Hilliard, J.; Hetrick, J.M.; AbuHassan, L.H.; Plisch, M.; Nayfeh, M.H. (Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (United States))

    1993-10-01

    Various metals were deposited on luminescent porous silicon (PS) by immersion in metal ion solutions and by evaporation. The photoluminescence (PL) was quenched upon immersion in ionic solutions of Cu, Ag, and Au but not noticeably quenched in other ionic solutions. Evaporation of 100 A of Cu or 110 A of Au was not observed to quench PL. Auger electron spectroscopy performed on samples quenched and then immediately removed from solution showed a metallic concentration in the PS layer of order 10 at.%, but persisting to a depth of order 3000 A.

  16. Luminescence Decay Times and Bimolecular Quenching: An Ultrafast Kinetics Experiment

    Science.gov (United States)

    Demas, J. N.

    1976-01-01

    Describes the theory, apparatus, and procedure for an experiment that measures the bimolecular quenching constant for the deactivation of an excited ruthenium ion complex using dissolved oxygen. (MLH)

  17. Quench Analysis of the PANDA Target Spectrometer Solenoid

    CERN Document Server

    Deelen, Nikkie

    2014-01-01

    A quench analysis of the PANDA Target Solenoid has been performed. The characteristic time of the fast discharge is $12\\ \\text{s}$. The peak temperature and peak voltage during a quench are $30\\ \\text{K}$ and $160\\ \\text{V}$ respectively. During a quench the energy stored in the magnetic field is mostly dissipated in the dump resistor. The slow discharge of the PANDA solenoid takes approximately $1950\\ \\text{s}$ during which nearly all the energy is dissipated in the diodes of the quench protection circuit.

  18. CLIQ. A new quench protection technology for superconducting magnets

    CERN Document Server

    Ravaioli, Emmanuele; ten Kate, H H J

    CLIQ, the Coupling-Loss Induced Quench system, is a new method for protecting superconducting magnets after a sudden transition to the normal state. It offers significant advantages over the conventional technology due to its effective mechanism for heating the superconductor relying on coupling loss and its robust electrical design, which makes it more reliable and less interfering with the coil winding process. The analysis of the electro-magnetic and thermal transients during and after a CLIQ discharge allows identifying the system parameters that affect the system performance and defining guidelines for implementing this technology on coils of various characteristics. Most existing superconducting magnets can be protected by CLIQ as convincingly shown by test results performed on magnets of different sizes, superconductor types, geometries, cables and strand parameters. Experimental results are successfully reproduced by means of a novel technique for modeling non-linear dynamic effects in superconducting...

  19. Properties of splat-quenched 7075 aluminum type alloys

    Science.gov (United States)

    Durand, J. P. H. A.; Pelloux, R. M.; Grant, N. J.

    1976-01-01

    The 7075 alloy belonging to the Al-Zn-Mg-Cu system, prepared by powder metallurgy techniques, was used in a study of alloys prepared from splat-quenched foils consolidated into bar material by hot extrusion. Ni and Fe were included in one alloy specimen, producing a fine dispersion of FeAl3 type particles which added to the strength of the aged alloy but did not coarsen upon heat treatment. Fine oxide films showing up on air-splatted foils induce finely dispersed oxide stringers (if the foils are not hot-worked subsequently) which in turn promote axial cracking (but longitudinal tensile strength is not seriously impaired). Splatting in a protective atmosphere, or thermomechanical processing, is recommended to compensate for this.

  20. Superradiance Transition and Nonphotochemical Quenching in Photosynthetic Complexes

    CERN Document Server

    Berman, Gennady P; López, Gustavo V; Sayre, Richard T

    2015-01-01

    We demonstrate numerically that superradiance could play a significant role in nonphotochemical quenching (NPQ) in light-harvesting complexes. Our model consists of a network of five interconnected sites (discrete excitonic states) that are responsible for the NPQ mechanism. Damaging and charge transfer states are linked to their sinks (independent continuum electron spectra), in which the chemical reactions occur. The superradiance transition in the charge transfer (or in the damaging) channel, occurs at particular electron transfer rates from the discrete to the continuum electron spectra, and can be characterized by a segregation of the imaginary parts of the eigenvalues of the effective non-Hermitian Hamiltonian. All five excitonic sites interact with their protein environment that is modeled by a random stochastic process. We find the region of parameters in which the superradiance transition into the charge transfer channel takes place. We demonstrate that this superradiance transition has the capabilit...

  1. Single-photon avalanche photodiodes with integrated quenching resistor

    Energy Technology Data Exchange (ETDEWEB)

    Mazzillo, M. [STMicroelectronics, IMS R and D Stradale Primosole 50, 95121 Catania (Italy)], E-mail: massimo.mazzillo@st.com; Condorelli, G.; Piazza, A.; Sanfilippo, D.; Valvo, G.; Carbone, B.; Fallica, G. [STMicroelectronics, IMS R and D Stradale Primosole 50, 95121 Catania (Italy); Billotta, S.; Belluso, M.; Bonanno, G. [INAF-Osservatorio Astrofisico di Catania, Via Santa Sofia 78, 95123 Catania (Italy); Pappalardo, A.; Cosentino, L.; Finocchiaro, P. [INFN-Laboratori Nazionali del Sud, Via Santa Sofia 64, 95125 Catania (Italy)

    2008-06-21

    In this paper we present the results of the first electrical and optical characterization performed on STMicroelectronics new photosensor technology based on silicon single-photon avalanche photodiodes (SPAD). On the prospective of the design and the manufacturing of large-area silicon photomultipliers to be used as photodetectors for nuclear medicine imaging applications, we have modified our previous SPAD technology by means of the integration of a high-value quenching resistor to the photodiode. Moreover, an appropriate antireflective coating layer and the reduction of the quasi-neutral region thickness above the thin junction depletion layer have been introduced in the process flow of the device to enhance its spectral response in blue and near ultraviolet wavelength ranges. High gain, low leakage currents, low dark noise, very good quantum detection efficiency in blue-near UV ranges and a good linearity of the photodiode response to the incident luminous flux are the main characterization results.

  2. Fluorescence quenching study of 2,6-bis(5-(4-methylphenyl)-1-H-pyrazol-3-yl)pyridine with metal ions.

    Science.gov (United States)

    Liu, Hua; Li, Fang-Xiong; Pi, Yan; Wang, Dun-Jia; Hu, Yan-Jun; Zheng, Jing

    2015-06-15

    A novel bispyrazole derivative 2,6-bis(5-(4-methylphenyl)-1-H-pyrazol-3-yl)pyridine was synthesized and its structure was confirmed by (1)H NMR, FTIR, MS techniques and elemental analysis. The binding interactions of BMPP with Cd(2+), Co(2+), Pb(2+) and Cu(2+) ions were investigated in MeOH-H2O solution by fluorescence quenching technique at two temperatures (25 and 35°C). Their quenching constants KSV, binding constants K, binding sites n and thermodynamic parameters (ΔH, ΔG and ΔS) were determined. The results indicated that the metal ions quenched the intrinsic fluorescence of the bispyrazole by forming the bispyrazole-metal complexes and their quenching process was a static quenching mechanism. In addition, the process of interaction was spontaneous and mainly ΔS-driven.

  3. Charmonium properties in hot quenched lattice QCD

    CERN Document Server

    Ding, H -T; Kaczmarek, O; Karsch, F; Satz, H; Soeldner, W

    2012-01-01

    We study the properties of charmonium states at finite temperature in quenched QCD on large and fine isotropic lattices. We perform a detailed analysis of charmonium correlation and spectral functions both below and above $T_c$. Our analysis suggests that both S wave states ($J/\\psi$ and $\\eta_c$) and P wave states ($\\chi_{c0}$ and $\\chi_{c1}$) disappear already at about $1.5 T_c$. The charm diffusion coefficient is estimated through the Kubo formula and found to be compatible with zero below $T_c$ and approximately $1/\\pi T$ at $1.5 T_c\\lesssim T\\lesssim 3 T_c$.

  4. Charmonium properties in hot quenched lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Ding, H. -T.; Francis, A.; Kaczmarek, O.; Karsch, F.; Satz, H.; Soeldner, W.

    2012-07-01

    We study the properties of charmonium states at finite temperature in quenched QCD on large and fine isotropic lattices. We perform a detailed analysis of charmonium correlation and spectral functions both below and above Tc. Our analysis suggests that both S wave states (J/ψ and ηc) and P wave states (χc0 and χc1) disappear already at about 1.5Tc. The charm diffusion coefficient is estimated through the Kubo formula and found to be compatible with zero below Tc and approximately 1/πT at 1.5Tc≲T≲3Tc.

  5. Thermal dilepton rates from quenched lattice QCD

    CERN Document Server

    Ding, H -T; Kaczmarek, O; Karsch, F; Laermann, E; Mukherjee, S; Müller, M; Soeldner, W

    2013-01-01

    We present new lattice results on the continuum extrapolation of the vector current correlation function. Lattice calculations have been carried out in the deconfined phase at a temperature of 1.1 Tc, extending our previous results at 1.45 Tc, utilizing quenched non-perturbatively clover-improved Wilson fermions and light quark masses. A systematic analysis on multiple lattice spacings allows to perform the continuum limit of the correlation function and to extract spectral properties in the continuum limit. Our current analysis suggests the results for the electrical conductivity are proportional to the temperature and the thermal dilepton rates in the quark gluon plasma are comparable for both temperatures. Preliminary results of the continuum extrapolated correlation function at finite momenta, which relates to thermal photon rates, are also presented.

  6. Magnetic Barkhausen Noise in quenched carburized steels

    Energy Technology Data Exchange (ETDEWEB)

    De Campos, M F; Santos, R; Da Silva, F S; Lins, J F C [PUVR- Universidade Federal Fluminense, Av dos Trabalhadores 420, Vila Santa Cecilia, Volta Redonda, RJ, 27255-125 (Brazil); Franco, F A; Ribeiro, S B; Padovese, L R, E-mail: mcampos@metal.eeimvr.uff.br, E-mail: mfdcampo@uol.com.br [Escola Politecnica, Universidade de Sao Paulo, Sao Paulo, SP (Brazil)

    2011-07-06

    Steels with different carbon content, 0.11%C and 0.48%C were submitted to a heat treatment for carburization in the surface. The samples were analyzed after several types of heat treatment, including quenching for producing martensite. The Magnetic Barkhausen Noise (MBN) is directly related to the microstructure. Samples with lower carbon content, have ferrite, a constituent where domain walls can move freely and present higher amplitude in the envelope of MBN. It is also found that the MBN peaks are quite distinct for the samples with martensite, which have lower permeability, and the results suggest that domain rotation contributes as mechanism for reversal of magnetization in martensite. The results also indicate that MBN is very suitable for monitoring the carburizing heat treatment.

  7. Magnetic Barkhausen Noise in quenched carburized steels

    Science.gov (United States)

    de Campos, M. F.; Franco, F. A.; Santos, R.; da Silva, F. S.; Ribeiro, S. B.; Lins, J. F. C.; Padovese, L. R.

    2011-07-01

    Steels with different carbon content, 0.11%C and 0.48%C were submitted to a heat treatment for carburization in the surface. The samples were analyzed after several types of heat treatment, including quenching for producing martensite. The Magnetic Barkhausen Noise (MBN) is directly related to the microstructure. Samples with lower carbon content, have ferrite, a constituent where domain walls can move freely and present higher amplitude in the envelope of MBN. It is also found that the MBN peaks are quite distinct for the samples with martensite, which have lower permeability, and the results suggest that domain rotation contributes as mechanism for reversal of magnetization in martensite. The results also indicate that MBN is very suitable for monitoring the carburizing heat treatment.

  8. Collisional quenching of highly rotationally excited HF

    CERN Document Server

    Yang, Benhui; Forrey, R C; Stancil, P C; Balakrishnan, N

    2015-01-01

    Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations of the interstellar gas for nonlocal thermodynamic equilibrium line formation. Theoretical cross sections and rate coefficients for collisional deexcitation of rotationally excited HF in the vibrational ground state are reported. The quantum-mechanical close-coupling approach implemented in the nonreactive scattering code MOLSCAT was applied in the cross section and rate coefficient calculations on an accurate 2D HF-He potential energy surface. Estimates of rate coefficients for H and H$_2$ colliders were obtained from the HF-He collisional data with a reduced-potential scaling approach. The calculation of state-to-state rotational quenching cross sections for HF due to He with initial rotational levels up to $j=20$ were performed for kinetic energies from 10$^{-5}$ to 15000...

  9. Orientifold Planar Equivalence: The Quenched Meson Spectrum

    CERN Document Server

    Lucini, Biagio; Patella, Agostino; Rago, Antonio

    2010-01-01

    A numerical study of Orientifold Planar Equivalence is performed in SU(N) Yang-Mills theories for N=2,3,4,6. Quenched meson masses are extracted in the antisymmetric, symmetric and adjoint representations for the pseudoscalar and vector channels. An extrapolation of the vector mass as a function of the pseudoscalar mass to the large-N limit shows that the numerical results agree within errors for the three theories, as predicted by Orientifold Planar Equivalence. As a byproduct of the extrapolation, the size of the corrections up to O(1/N^3) are evaluated. A crucial prerequisite for the extrapolation is the determination of an analytical relationship between the corrections in the symmetric and in the antisymmetric representations, order by order in a 1/N expansion.

  10. Quenched mesonic spectrum at large N

    CERN Document Server

    Del Debbio, Luigi; Patella, Agostino; Pica, Claudio

    2008-01-01

    We compute the masses of the $\\pi$ and of the $\\rho$ mesons in the quenched approximation on a lattice with fixed lattice spacing $a \\simeq 0.145 \\ \\mathrm{fm}$ for SU($N$) gauge theory with $N = 2,3,4,6$. We find that a simple linear expression in $1/N^2$ correctly captures the features of the lowest-lying meson states at those values of $N$. This enables us to extrapolate to $N = \\infty$ the behaviour of $m_{\\pi}$ as a function of the quark mass and of $m_{\\rho}$ as a function of $m_{\\pi}$. Our results for the latter agree within 5% with recent predictions obtained in the AdS/CFT framework.

  11. Study on the Interaction between Cephalosporin Drugs and Papain by Spectroscopic Method: Equivalence of Fluorescence Quenching and Enhancement Equation%Study on the Interaction between Cephalosporin Drugs and Papain by Spectroscopic Method: Equivalence of Fluorescence Quenching and Enhancement Equation

    Institute of Scientific and Technical Information of China (English)

    杨曼曼; 席小莉; 杨频

    2011-01-01

    The interaction between two 4th generation of new cephalosporin drugs and papain was studied through spectroscopy method at different temperatures. Their dissociation constants were calculated by using theoretical formula of fluorescence quenching and fluorescence enhancement, respectively, and their corresponding thermodynamic functions, dipole-dipole non-radiative energy-transfer-efficiency and the action distances of acceptor-substrate etc. were calculated further. Analysis reveals that, the quenching on papain by cefpirome and cefepime is basically due to the dipole-dipole non-radiation energy-transfer and certain dynamic collision between donor and acceptor, the interaction between drug and papain is mainly hydrophobic which may provide useful information for pharmacological and metabolic study on papain. In this paper fluorescence quenching is regarded as negative fluorescence enhancement, and two kinds of theoretical formula of fluorescence quenching and fluorescence enhancement were used to calculate the experimental data of fluorescence quenching of a same batch, and very close results were obtained but with certain difference. The results not only display the equivalence of the two theoretical equations when treating acceptor-substrate action, but also show that the thermodynamic data based on the theoretical formula of fluorescence enhancement (4), which is deduced by us, are more reasonable. So we suggest that even in the process of studying the fluorescence quenching between receptor-substrate, using the theoretical formula of fluorescence enhancement (4) can get more reliable results.

  12. Stability and quench development study in small HTSC magnet

    NARCIS (Netherlands)

    Ilyin, Yu. A.; Vysotski, V.S.; Kiss, T.; Takeo, M.; Okamoto, H.; Irie, F.

    2001-01-01

    Stability and quench development in a HTSC magnet have been experimentally studied with the transport current in the magnet being below or above the “thermal quench current” level. The magnet was tested at both cryocooler cooling and liquid nitrogen cooling, with and without background magnetic fiel

  13. The quenched generating functional for hadronic weak interactions

    NARCIS (Netherlands)

    Pallante, E.

    1999-01-01

    The ultraviolet behaviour of the generating functional for hadronic weak interactions with |ΔS| = 1, 2 is investigated to one loop for a generic number of flavours and in the quenched approximation. New quenched chiral logarithms generated by the weak interactions can be accounted for via a redefin

  14. Stability and quench development study in small HTSC magnet

    NARCIS (Netherlands)

    Ilyin, Y.; Vysotski, V.S.; Kiss, T.; Takeo, M.; Okamoto, H.; Irie, F.

    2001-01-01

    Stability and quench development in a HTSC magnet have been experimentally studied with the transport current in the magnet being below or above the “thermal quench current” level. The magnet was tested at both cryocooler cooling and liquid nitrogen cooling, with and without background magnetic

  15. QUENCHING PROBLEMS OF DEGENERATE FUNCTIONAL REACTION-DIFFUSION EQUATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper is concerned with the quenching problem of a degenerate functional reaction-diffusion equation. The quenching problem and global existence of solution for the reaction-diffusion equation are derived and, some results of the positive steady state solutions for functional elliptic boundary value are also presented.

  16. Quenched transmission of light through ultrathin metal films

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Mortensen, N. Asger

    2011-01-01

    We discuss optical properties of ultrathin metal films, with particular attention to the phenomenon of quenched transmission. Transmission of light through an optically ultrathin metal film with a thickness comparable to its skin depth is significant. We demonstrate the quenched transmission thro...

  17. Chiral and continuum extrapolation of partially quenched lattice results

    Energy Technology Data Exchange (ETDEWEB)

    C.R. Allton; W. Armour; D.B. Leinweber; A.W. Thomas; R.D. Young

    2005-04-01

    The vector meson mass is extracted from a large sample of partially quenched, two-flavor lattice QCD simulations. For the first time, discretization, finite-volume and partial quenching artifacts are treated in a unified chiral effective field theory analysis of the lattice simulation results.

  18. Investigating the cooling rate of cane molasses as quenching medium for 0.61% C high carbon steels

    Directory of Open Access Journals (Sweden)

    M. R. Dodo

    2016-03-01

    Full Text Available The effect of cooling rate of cane molasses as quenching medium for 0.61% C high carbon steels was investigated. Samples of high carbon steel were spheroidized annealed and then machined prior to the hardening process. Molasses solution of viscosity equals to that of engine oil was prepared by adding water. The samples were normalized and then austenitised at 800oC and soaked for 40 minutes and then quenched in water, engine oil, raw molasses and the prepared molasses solution. Cooling rate curves of all the quenching media used were developed. The highest cooling rate of 60oC/s was attained by the prepared molasses solution. Hardness of the test samples was evaluated. The test results obtained show that the highest hardness value (525 HVN was obtained from the sample quenched in the prepared molasses solution. Microstructures of the various samples were analyzed using OM and SEM. In all the tests samples martensite structure was observed. It was observed that the prepared molasses solution has higher severity of quenching than that of engine oil but lower than that of water. The research showed that cane molasses can harden high carbon steel without cracking the component in the same way as engine oil, hence, molasses could be a very good alternative to engine oil for use as quenching medium.

  19. Chiral Loops and Ghost States in the Quenched Scalar Propagator

    Energy Technology Data Exchange (ETDEWEB)

    W. Bardeen; A. Duncan; E. Eichten; N. Isgur; H. Thacker

    2001-06-01

    The scalar, isovector meson propagator is analyzed in quenched QCD, using the MQA pole-shifting ansatz to study the chiral limit. In addition to the expected short-range exponential falloff characteristic of a heavy scalar meson, the propagator also exhibits a longer-range, negative metric contribution which becomes pronounced for smaller quark masses. We show that this is a quenched chiral loop effect associated with the anomalous structure of the eta' propagator in quenched QCD. Both the time dependence and the quark mass dependence of this effect are well-described by a chiral loop diagram corresponding to an eta'-pi intermediate state, which is light and effectively of negative norm in the quenched approximation. The relevant parameters of the effective Lagrangian describing the scalar sector of the quenched theory are determined.

  20. Dynamics of Holographic Entanglement Entropy Following a Local Quench

    CERN Document Server

    Rangamani, Mukund; Vincart-Emard, Alexandre

    2015-01-01

    We discuss the behaviour of holographic entanglement entropy following a local quench in 2+1 dimensional strongly coupled CFTs. The entanglement generated by the quench propagates along an emergent light-cone, reminiscent of the Lieb-Robinson light-cone propagation of correlations in non-relativistic systems. We find the the speed of propagation is bounded from below by the entanglement tsunami velocity obtained earlier for global quenches in holographic systems, and from above by the speed of light. The former is realized for sufficiently broad quenches, while the latter pertains for well localized quenches. The non-universal behavior in the intermediate regime appears to stem from finite-size effects. We also note that the entanglement entropy of subsystems reverts to the equilibrium value exponentially fast, in contrast to a much slower equilibration seen in certain spin models.

  1. ITER Side Correction Coil Quench model and analysis

    Science.gov (United States)

    Nicollet, S.; Bessette, D.; Ciazynski, D.; Duchateau, J. L.; Gauthier, F.; Lacroix, B.

    2016-12-01

    Previous thermohydraulic studies performed for the ITER TF, CS and PF magnet systems have brought some important information on the detection and consequences of a quench as a function of the initial conditions (deposited energy, heated length). Even if the temperature margin of the Correction Coils is high, their behavior during a quench should also be studied since a quench is likely to be triggered by potential anomalies in joints, ground fault on the instrumentation wires, etc. A model has been developed with the SuperMagnet Code (Bagnasco et al., 2010) for a Side Correction Coil (SCC2) with four pancakes cooled in parallel, each of them represented by a Thea module (with the proper Cable In Conduit Conductor characteristics). All the other coils of the PF cooling loop are hydraulically connected in parallel (top/bottom correction coils and six Poloidal Field Coils) are modeled by Flower modules with equivalent hydraulics properties. The model and the analysis results are presented for five quench initiation cases with/without fast discharge: two quenches initiated by a heat input to the innermost turn of one pancake (case 1 and case 2) and two other quenches initiated at the innermost turns of four pancakes (case 3 and case 4). In the 5th case, the quench is initiated at the middle turn of one pancake. The impact on the cooling circuit, e.g. the exceedance of the opening pressure of the quench relief valves, is detailed in case of an undetected quench (i.e. no discharge of the magnet). Particular attention is also paid to a possible secondary quench detection system based on measured thermohydraulic signals (pressure, temperature and/or helium mass flow rate). The maximum cable temperature achieved in case of a fast current discharge (primary detection by voltage) is compared to the design hot spot criterion of 150 K, which includes the contribution of helium and jacket.

  2. Comparative effects of thermal quenching and ballistic collisions in SiO2-B2O3-Na2O glass

    Science.gov (United States)

    Delaye, J.-M.; Peuget, S.; Calas, G.; Galoisy, L.

    2014-05-01

    The differences between the effects of irradiation and thermal quenching were studied in SiO2-B2O3-Na2O glass by molecular dynamics. Classical molecular dynamics simulations reproduced quenching rates between 2 × 1012 K/s and instantaneous quenching. Each configuration was then subjected to a series of displacement cascades. An acceleration of the quenching rate and the accumulation of ballistic collisions result in qualitatively similar effects: swelling, increasing disorder, depolymerization of the glassy network, a decrease in the mean coordination number of B atoms. Nevertheless, ballistic processes induce specific effects that are not reproduced by accelerated quenching: an even larger degree of disorder, higher potential energy, greater depolymerization around B sites and different free volume distribution. The memory of the initial quenching rate is largely lost following an accumulation of displacement cascades, and the structure of the irradiated glasses adopts a final configuration weakly dependant on the initial state. This study shows that comparing the structure of the initial glass prepared at different quenching rates with the structure of irradiated glasses makes it possible to discriminate between thermal quenching and ballistic effects.

  3. Star formation quenching in simulated group and cluster galaxies: When, how, and why?

    CERN Document Server

    Bahe, Yannick M

    2014-01-01

    Star formation is observed to be suppressed in group and cluster galaxies compared to the field. To gain insight into the quenching process, we have analysed ~2000 galaxies formed in the GIMIC suite of cosmological hydrodynamical simulations. The time of quenching varies from ~2 Gyr before accretion (first crossing of r200,c) to >4 Gyr after, depending on satellite and host mass. Once begun, quenching is rapid (>~ 500 Myr) in low-mass galaxies (M* < 10^10 M_Sun), but significantly more protracted for more massive satellites. The simulations predict a substantial role of outflows driven by ram pressure -- but not tidal forces -- in removing the star-forming interstellar matter (ISM) from satellite galaxies, especially dwarfs (M* ~ 10^9 M_Sun) where they account for nearly two thirds of ISM loss in both groups and clusters. Immediately before quenching is complete, this fraction rises to ~80% even for Milky Way analogues (M* ~ 10^10.5 M_Sun) in groups (M_host ~ 10^13.5 M_Sun). We show that (i) ISM stripping ...

  4. Satellite quenching timescales in clusters from projected phase space measurements matched to simulated orbits

    CERN Document Server

    Oman, Kyle A

    2016-01-01

    We measure the star formation quenching efficiency and timescale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed SDSS galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample ($10^{9}-10^{11.5}\\,{\\rm M}_\\odot$) by massive ($> 10^{13}\\,{\\rm M}_\\odot$) clusters is essentially $100$ per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first peric...

  5. Determination of torasemide by fluorescence quenching method with some dihalogenated fluorescein dyes as probes

    Science.gov (United States)

    Cui, Zhiping; Liu, Shaopu; Liu, Zhongfang; Li, Yuanfang; Hu, Xiaoli; Tian, Jing

    2013-10-01

    A novel fluorescence quenching method for the determination of torasemide (TOR) with some dihalogenated fluorescein dyes as fluorescence probes was developed. In acidulous medium, TOR could interact with some dihalogenated fluorescein dyes such as dichlorofluorescein (DCF), dibromofluorescein (DBF) and diiodofluorescein (DIF) to form binary complexes, which could lead to fluorescence quenching of above dihalogenated fluorescein dyes. The maximum fluorescence emission wavelengths were located at 532 nm (TOR-DCF), 535 nm (TOR-DBF) and 554 nm (TOR-DIF). The relative fluorescence intensities (ΔF = F0 - F) were proportional to the concentration of TOR in certain ranges. The detection limits were 4.8 ng mL-1 for TOR-DCF system, 9.8 ng mL-1 for TOR-DBF system and 35.1 ng mL-1 for TOR-DIF system. The optimum reaction conditions, influencing factors were studied; and the effect of coexisting substances was investigated owing to the highest sensitivity of TOR-DCF system. In addition, the reaction mechanism, composition and structure of the complex were discussed by quantum chemical calculation and Job's method. The fluorescence quenching of dihalogenated fluorescein dyes by TOR was a static quenching process judging from the effect of temperature and the Stern-Volmer plots. The method was satisfactorily applied to the determination of TOR in tablets and human urine samples.

  6. Quench propagation in High Temperature Superconducting materials integrated in high current leads

    CERN Document Server

    Milani, D

    2001-01-01

    High temperature superconductors (HTS) have been integrated in the high current leads for the Large Hadron Collider (LHC), under construction at CERN, in order to reduce the heat leak into the liquid helium bath due to the joule effect. The use of the HTS technology in the lower part of the current leads allowed to significantly reduce the heat charge on the cryogenic system. Hybrid current leads have been designed to fulfill the LHC requirements with respect to thermal load; several tests have been performed to study the lead behavior especially during a quench transient. Quench experiments have been performed at CERN on 13 kA prototypes to determine the adequate design and protection. In all the tests it is possible to know the temperature profile of the HTS only with the help of quench simulations that model the thermo-hydraulic processes during quench. The development of a theoretical model for the simulation allows reducing the number of test to perform and to scale the experimental result to other curre...

  7. Quench protection analysis integrated in the design of dipoles for the Future Circular Collider

    CERN Document Server

    Salmi, Tiina-Mari; Prioli, Marco; Ruuskanen, Janne Johannes; Verweij, Arjan; Auchmann, Bernhard; Tommasini, Davide; Schoerling, Daniel; Lorin, Clement; Toral, Fernando; Durante, Maria; Farinon, Stefania; Marinozzi, Vittorio; Fabbricatore, Pasquale; Sorbi, Massimo Leone; Munilla Lopez, Javier

    2017-01-01

    The EuroCirCol collaboration is designing a 16 T Nb$_3$Sn dipole that can be used as the main bending magnet in a 100 km long 100 TeV hadron-hadron collider. For economic reasons, the magnets need to be as compact as possible, requiring optimization of the cable cross section in different magnetic field regions. This leads to very high stored energy density and poses serious challenges for the magnet protection in case of a quench, i.e., sudden loss of superconductivity in the winding. The magnet design therefore must account for the limitations set by quench protection from the earliest stages of the design. In this paper we describe how the aspect of quench protection has been accounted for in the process of developing different options for the 16 T dipole designs. We discuss the assumed safe values for hot spot temperatures and voltages, and the efficiency of the protection system. We describe the developed tools for the quench analysis, and how their usage in the magnet design will eventually ensure a sec...

  8. Star Formation Quenching Timescale of Central Galaxies in a Hierarchical Universe

    CERN Document Server

    Hahn, ChangHoon; Wetzel, Andrew R

    2016-01-01

    Central galaxies make up the majority of the galaxy population, including the majority of the quiescent population at $\\mathcal{M}_* > 10^{10}\\mathrm{M}_\\odot$. Thus, the mechanism(s) responsible for quenching central galaxies plays a crucial role in galaxy evolution as whole. We combine a high resolution cosmological $N$-body simulation with observed evolutionary trends of the "star formation main sequence," quiescent fraction, and stellar mass function at $z < 1$ to construct a model that statistically tracks the star formation histories and quenching of central galaxies. Comparing this model to the distribution of central galaxy star formation rates in a group catalog of the SDSS Data Release 7, we constrain the timescales over which physical processes cease star formation in central galaxies. Over the stellar mass range $10^{9.5}$ to $10^{11} \\mathrm{M}_\\odot$ we infer quenching e-folding times that span $1.5$ to $0.5\\; \\mathrm{Gyr}$ with more massive central galaxies quenching faster. For $\\mathcal{M}...

  9. Quench and partitioning steel: a new AHSS concept for automotive anti-intrusion applications

    Energy Technology Data Exchange (ETDEWEB)

    De Cooman, B.C. [Graduate Inst. for Ferrous Technology, Pohang Univ. of Science and Technology, Pohang (Korea); Speer, J.G. [Advanced Steel Processing and Products Research Centre, Colorado School of Mines, Golden, CO (United States)

    2006-09-15

    A new type of high strength, high toughness, martensitic steel, based on a newly proposed quench and partitioning (Q and P) process, is presented. This high strength martensitic grade is produced by the controlled low temperature partitioning of carbon from as-quenched martensite laths to retained inter-lath austenite under conditions where both low temperature transition carbide formation and cementite precipitation are suppressed. The contribution focuses on both the current understanding of the fundamental processes involved and includes a discussion of the technical feasibility of large-scale industrial production of these steels as sheet products. The Q and P process, which is carried out on steels with a lean composition, should be implemented easily on some current industrial continuous annealing and galvanizing lines. In addition, martensitic Q and P sheet steel is characterized by very favourable combinations of strength, ductility and toughness, which are particularly relevant for high strength anti-intrusion automotive parts. (orig.)

  10. Quenching and Tempering for 42 CrMo4 Steel Forged Gear Ring%42 CrM o4钢锻辗齿圈的调质处理

    Institute of Scientific and Technical Information of China (English)

    王松林; 任秀凤; 张永庆; 刘守峰; 银伟; 王聪

    2014-01-01

    通过改进调质工艺,使用8%~10%的无机水基淬火液,改进淬火冷却工艺参数,解决了42CrMo4钢齿圈淬火开裂的问题。%By improving the tempering and quenching process , 8%~10%of inorganic water-based quenching liq-uid is used to improve the quench cooling process parameters and solve the crack problem during 42CrMo4 steel gear ring quenching .

  11. 40 CFR 1065.370 - CLD CO2 and H2O quench verification.

    Science.gov (United States)

    2010-07-01

    ... analyzer uses quench compensation algorithms that utilize H2O and/or CO2 measurement instruments, evaluate quench with these instruments active and evaluate quench with the compensation algorithms applied....

  12. Comparisons of four quench methods for high temperature Syngas-Exergy Analyses

    Science.gov (United States)

    Liu, Y. H.; Chen, W.; Che, D. F.; Cao, Z. D.

    2010-03-01

    Entrained flow slagging gasifiers have been found in many applications, one of which is IGCC. The quench of high temperature syngas from first stage of entrained flow slagging gasifiers is of great importance for the availability of gasifiers, and it influences the economical running of utilization system. Four kinds of quench methods including water quench, gas quench, radiant quench and chemical quench, are investigated by Gibbs free energy minimization and exergy analyses. The exergy distributions of the streams into and out of each quench system are obtained. The results show that exergy loss of water quench is the biggest, and the exergy loss of chemical quench is the least and can be neglectable. The exergy losses of the other two quench methods are comparable, which are only 1/3 smaller than that of water quench. Chemical quench not only features in lower oxygen consumption as well as a higher cold gas efficiency, but also has high exergy efficiency.

  13. Effect of twice quenching and tempering on the mechanical properties and microstructures of SCRAM steel for fusion application

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Xuesong; Yang Feng; Zou Xingrong [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Suo Jinping, E-mail: jpsuo@yahoo.com.cn [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2012-11-15

    The effect of twice quenching and tempering on the mechanical properties and microstructures of SCRAM steel was investigated. The results from tensile tests showed that whether twice quenching and tempering processes(1253 K/0.5 h/W.C(water cool) + 1033 K/2 h/A.C(air cool) + 1233 K/0.5 h/W.C + 1033 K/2 h/A.C named after 2Q and 2TI, and 1253 K/0.5 h/W.C + 1033 K/2 h/A.C + 1233 K/0.5 h/W.C + 1013 K/2 h/A.C named after 2Q and 2TII)increased strength of steel or not depended largely on the second tempering temperature compared to quenching and tempering process(1253 K/0.5 h/W.C + 1033 K/2 h/A.C named after 1Q and 1T). Charpy V-notch impact tests indicated that twice quenching and tempering processes reduced the ductile brittle transition temperature (DBTT). Microstructure inspection revealed that the prior austenitic grain size and martensite lath width were refined after twice quenching and tempering treatments. Precipitate growth was inhibited by a slight decrease of the second tempering temperature from 1033 to 1013 K. The finer average size of precipitates is considered to be the main possible reason for the higher strength and lower DBTT of 2Q and 2TII compared with 2Q and 2TI.

  14. Quenched Heavy-Light Decay Constants

    CERN Document Server

    Baxter, R M; Bowler, K C; Collins, S; Henty, D S; Kenway, R D; Richards, D G; Shanahan, H P; Simone, J N; Simpson, A D; Wilkes, B E; Ewing, A K; Lellouch, L P; Sachrajda, Christopher T C; Wittig, H

    1994-01-01

    We present results for heavy-light decay constants, using both propagating quarks and the static approximation, in O(a)-improved, quenched lattice QCD. At beta=6.2 on a 24^3x48 lattice we find f_D=185 +4-3(stat)+42-7(syst) MeV, f_B=160 +6-6 +53-19 MeV, f_{D_s}/f_D=1.18 +2-2 and f_{B_s}/f_B=1.22 +4-3, in good agreement with earlier studies. From the static theory we obtain f_B^stat=253 +16-15 +105-14 MeV. We also present results from a simulation at beta=6.0 on a 16^3x48 lattice, which are consistent with those at beta=6.2. In order to study the effects of improvement, we present a direct comparison of the results using both the Wilson and the improved action at beta=6.0.

  15. Nonequilibrium States of a Quenched Bose Gas

    Science.gov (United States)

    Ling, Hong; Kain, Ben

    2014-05-01

    Yin and Radzihovsky [Phys. Rev. A 88, 063611 (2014)] recently developed a self-consistent extension of a Bogoliubov theory, in which the condensate number density, nc, is treated as a mean field that changes with time in order to analyze a JILA experiment by Makotyn et al. [Nature Physics doi:10.1038/nphys2850 (2014)] on a 85Rb Bose gas following a deep quench to a large scattering length. We apply this theory to construct a set of closed equations that highlight the role of dnc/dt, which is to induce an effective interaction between quasiparticles. We show analytically that such a system supports a steady state characterized by a constant condensate density and a steady but periodically changing momentum distribution, whose time average is described exactly by the generalized Gibbs ensemble. We discuss how the dnc/dt-induced effective interaction, which cannot be ignored on the grounds of the adiabatic approximation for modes near the gapless Goldstone mode, can affect experimentally measurable quantities such as Tan's contact. This work is supported in part by the US Army Research Office under Grant No. W911NF-10-1-0096 and in part by the US National Science Foundation under Grant No. PHY11-25915.

  16. Quenching parameter in a holographic thermal QCD

    CERN Document Server

    Patra, Binoy Krishna

    2016-01-01

    We have calculated the quenching parameter, $\\hat{q}$ in a model-independent way using the gauge-gravity duality. In earlier calculations, the geometry in the gravity side at finite temperature was usually taken as the pure AdS blackhole metric for which the dual gauge theory becomes conformally invariant unlike QCD. Therefore we use a metric which incorporates the fundamental quarks by embedding the coincident D7 branes in the Klebanov-Tseytlin background and a finite temperature is switched on by inserting a black hole into the background, known as OKS-BH metric. Further inclusion of an additional UV cap to the metric prepares the dual gauge theory to run similar to thermal QCD. Moreover $\\hat{q}$ is usually defined in the literature from the Glauber-model perturbative QCD evaluation of the Wilson loop, which has no reasons to hold if the coupling is large and is thus against the main idea of gauge-gravity duality. Thus we use an appropriate definition of $\\hat{q}$: $\\hat{q} L^- = 1/L^2$, where $L$ is the s...

  17. Quorum Quenching Agents: Resources for Antivirulence Therapy

    Directory of Open Access Journals (Sweden)

    Kaihao Tang

    2014-05-01

    Full Text Available The continuing emergence of antibiotic-resistant pathogens is a concern to human health and highlights the urgent need for the development of alternative therapeutic strategies. Quorum sensing (QS regulates virulence in many bacterial pathogens, and thus, is a promising target for antivirulence therapy which may inhibit virulence instead of cell growth and division. This means that there is little selective pressure for the evolution of resistance. Many natural quorum quenching (QQ agents have been identified. Moreover, it has been shown that many microorganisms are capable of producing small molecular QS inhibitors and/or macromolecular QQ enzymes, which could be regarded as a strategy for bacteria to gain benefits in competitive environments. More than 30 species of marine QQ bacteria have been identified thus far, but only a few of them have been intensively studied. Recent studies indicate that an enormous number of QQ microorganisms are undiscovered in the highly diverse marine environments, and these marine microorganism-derived QQ agents may be valuable resources for antivirulence therapy.

  18. Systematic study of particle quenching in organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, L.M.; Bagán, H. [Department of Analytical Chemistry of the University of Barcelona, Diagonal 645, E-08028 Barcelona (Spain); Tarancón, A., E-mail: alex.tarancon@ub.edu [Department of Analytical Chemistry of the University of Barcelona, Diagonal 645, E-08028 Barcelona (Spain); Rauret, G.; Garcia, J.F. [Department of Analytical Chemistry of the University of Barcelona, Diagonal 645, E-08028 Barcelona (Spain)

    2013-01-11

    Among the different factors that affect measurements by organic scintillators, the majority of attention has been focused on those related to the scintillator (i.e., ionization, chemical, color and optical quenching), and less attention has been paid to the loss of energy before the particle (i.e., alpha or beta) arrives at the scintillator (i.e., particle quenching). This study evaluates the effect of particle quenching in different scintillation methods (i.e., using two plastic scintillation microspheres (PSm1 and PSm2), liquid scintillator and gel scintillator) by measuring solutions that contain increasing concentrations of NaCl, BaCl{sub 2} and glycerin. The results show the importance of particle quenching in PSm measurements because detection efficiency decreases with increasing concentrations of the quenching component, although the spectrum position and external standard parameter remain constant. The results have shown evidence of particle quenching, although at a lower magnitude, in the liquid scintillation or gel scintillation measurements. Moreover, the use of two PSm with different diameters and salty compound that alters the equilibrium of the liquid and gel emulsions also exemplified the importance of the transmission of optical photons through different scintillation media (i.e., optical quenching). Improvement and deterioration of the optical conditions on the scintillation media is manifested as a movement of the spectrum to higher and lower energies, respectively. The results obtained with PSm were confirmed by Monte Carlo simulation.

  19. The Mass Dependence of Dwarf Satellite Galaxy Quenching

    CERN Document Server

    Slater, Colin T

    2014-01-01

    We combine observations of the Local Group with data from the NASA-Sloan Atlas to show the variation in the quenched fraction of satellite galaxies from low mass dwarf spheroidals and dwarf irregulars to more massive dwarfs similar to the Magellanic clouds. While almost all of the low mass ($M_\\star \\lesssim 10^7$ $M_\\odot$) dwarfs are quenched, at higher masses the quenched fraction decreases to approximately 40-50%. This change in the quenched fraction is large, and suggests a sudden change in the effectiveness of quenching that correlates with satellite mass. We combine this observation with models of satellite infall and ram pressure stripping to show that the low mass satellites must quench within 1-2 Gyr of pericenter passage to maintain a high quenched fraction, but that many more massive dwarfs must continue to form stars today even though they likely fell in to their host >5 Gyr ago. We also characterize how the susceptibility of dwarfs to ram pressure must vary as a function of mass if it is to acco...

  20. Final Technical Report: Intensive Quenching Technology for Heat Treating and Forging Industries

    Energy Technology Data Exchange (ETDEWEB)

    Aronov, Michael A.

    2005-12-21

    Intensive quenching (IQ) process is an alternative way of hardening (quenching) steel parts through the use of highly agitated water and then still air. It was developed by IQ Technologies, Inc. (IQT) of Akron, Ohio. While conventional quenching is usually performed in environmentally unfriendly oil or water/polymer solutions, the IQ process uses highly agitated environmentally friendly water or low concentration water/mineral salt solutions. The IQ method is characterized by extremely high cooling rates of steel parts. In contrast to conventional quenching, where parts cool down to the quenchant temperature and usually have tensile or neutral residual surface stresses at the end of quenching. The IQ process is interrupted when the part core is still hot and when there are maximum compressive stresses deep into the parts, thereby providing hard, ductile, better wear resistant parts. The project goal was to advance the patented IQ process from feasibility to commercialization in the heat-treating and forging industries to reduce significantly energy consumption and environmental impact, to increase productivity and to enhance economic competitiveness of these industries as well as Steel, Metal Casting and Mining industries. To introduce successfully the IQ technology in the U.S. metal working industry, the project team has completed the following work over the course of this project: A total of 33 manufacturers of steel products provided steel parts for IQ trails. IQT conducted IQ demonstrations for 34 different steel parts. Our customers tested intensively quenched parts in actual field conditions to evaluate the product service life and performance improvement. The data obtained from the field showed the following: Service life (number of holes punched) of cold-work punches (provided by EHT customer and made of S5 shock-resisting steel) was improved by two to eight times. Aluminum extrusion dies provided by GAM and made of hot work H-13 steel outperformed the

  1. Femtosecond fluorescence spectra of tryptophan in human gamma-crystallin mutants: site-dependent ultrafast quenching.

    Science.gov (United States)

    Xu, Jianhua; Chen, Jiejin; Toptygin, Dmitri; Tcherkasskaya, Olga; Callis, Patrik; King, Jonathan; Brand, Ludwig; Knutson, Jay R

    2009-11-25

    The eye lens Crystallin proteins are subject to UV irradiation throughout life, and the photochemistry of damage proceeds through the excited state; thus, their tryptophan (Trp) fluorescence lifetimes are physiologically important properties. The time-resolved fluorescence spectra of single Trps in human gammaD- and gammaS-Crystallins have been measured with both an upconversion spectrophotofluorometer on the 300 fs to 100 ps time scale, and a time correlated single photon counting apparatus on the 100 ps to 10 ns time scale, respectively. Three Trps in each wild type protein were replaced by phenylalanine, leading to single-Trp mutants: W68-only and W156-only of HgammaD- and W72-only and W162-only of HgammaS-Crystallin. These proteins exhibit similar ultrafast signatures: positive definite decay associated spectra (DAS) for 50-65 ps decay constants that indicate dominance of fast, heterogeneous quenching. The quenched population (judged by amplitude) of this DAS differs among mutants. Trps 68, 156 in human gammaD- and Trp72 in human gammaS-Crystallin are buried, but water can reach amide oxygen and ring HE1 atoms through narrow channels. QM-MM simulations of quenching by electron transfer predict heterogeneous decay times from 50-500 ps that agree with our experimental results. Further analysis of apparent radiative lifetimes allow us to deduce that substantial subpopulations of Trp are fully quenched in even faster (sub-300 fs) processes for several of the mutants. The quenching of Trp fluorescence of human gammaD- and gammaS-Crystallin may protect them from ambient light induced photo damage.

  2. Quench-induced trapping of magnetic flux in annular

    DEFF Research Database (Denmark)

    Aaroe, M.; Monaco, R.; Rivers, R.;

    2008-01-01

    over 4 orders of magnitude. After the quench the result of the spontaneous production of topological defects, trapped fluxons, is unambiguously observed as zero-field steps in the DC I-V characteristic of the junction. A power-law scaling behavior of trapping probability versus quench rate is found...... with a critical exponent of 0.5 (within experimental error). The main experimental challenges are to generate many identical quenches with accurate cooling rate, to automate data analysis and acquisition, and to suppress external magnetic fields and noise by passive magnetic shielding and compensation....

  3. Dynamical quenching with non-local alpha and downward pumping

    CERN Document Server

    Brandenburg, A; Käpylä, P J

    2014-01-01

    In light of new results, the one-dimensional mean-field dynamo model of Brandenburg & Kapyla (2007) with dynamical quenching and a nonlocal Babcock-Leighton alpha effect is re-examined for the solar dynamo. We extend the one-dimensional model to include the effects of turbulent downward pumping (Kitchatinov & Olemskoy 2011), and to combine dynamical quenching with shear. We use both the conventional dynamical quenching model of Kleeorin & Ruzmaikin (1982) and the alternate one of Hubbard & Brandenburg (2011), and confirm that with varying levels of non-locality in the alpha effect, and possibly shear as well, the saturation field strength can be independent of the magnetic Reynolds number.

  4. Quench Dynamics in Confined 1+1-Dimensional Systems

    CERN Document Server

    Engelhardt, Dalit

    2015-01-01

    We present a scheme for investigating the response of confined 1+1-dimensional systems to a quantum quench and consider the extent to which a system whose post-quench dynamics are near-integrable may be analyzed by an application of boundary CFT techniques. As the main example we present a model of a split-momentum quench in a finite 1D geometry, a setup analogous to that of the experiment of Kinoshita, Wenger, and Weiss [Nature 440, 900 (2006)]. We analytically derive the form of the expected momentum distributions and describe how such information may be used to assess the extent of integrability breaking in realistic systems.

  5. Quantitative quenching evaluation and direct intracellular metabolite analysis in Penicillium chrysogenum.

    Science.gov (United States)

    Meinert, Sabine; Rapp, Sina; Schmitz, Katja; Noack, Stephan; Kornfeld, Georg; Hardiman, Timo

    2013-07-01

    Sustained progress in metabolic engineering methodologies has stimulated new efforts toward optimizing fungal production strains such as through metabolite analysis of Penicillium chrysogenum industrial-scale processes. Accurate intracellular metabolite quantification requires sampling procedures that rapidly stop metabolism (quenching) and avoid metabolite loss via the cell membrane (leakage). When sampling protocols are validated, the quenching efficiency is generally not quantitatively assessed. For fungal metabolomics, quantitative biomass separation using centrifugation is a further challenge. In this study, P. chrysogenum intracellular metabolites were quantified directly from biomass extracts using automated sampling and fast filtration. A master/slave bioreactor concept was applied to provide industrial production conditions. Metabolic activity during sampling was monitored by 13C tracing. Enzyme activities were efficiently stopped and metabolite leakage was absent. This work provides a reliable method for P. chrysogenum metabolomics and will be an essential base for metabolic engineering of industrial processes.

  6. Biofouling control: Bacterial quorum quenching versus chlorination in membrane bioreactors.

    Science.gov (United States)

    Weerasekara, Nuwan A; Choo, Kwang-Ho; Lee, Chung-Hak

    2016-10-15

    Biofilm formation (biofouling) induced via cell-to-cell communication (quorum sensing) causes problems in membrane filtration processes. Chorine is one of the most common chemicals used to interfere with biofouling; however, biofouling control is challenging because it is a natural process. This study demonstrates biofouling control for submerged hollow fiber membranes in membrane bioreactors by means of bacterial quorum quenching (QQ) using Rhodococcus sp. BH4 with chemically enhanced backwashing. This is the first trial to bring QQ alongside chlorine injection into practice. A high chlorine dose (100 mg/L as Cl2) to the system is insufficient for preventing biofouling, but addition of the QQ bacterium is effective for disrupting biofouling that cannot be achieved by chlorination alone. QQ reduces the biologically induced metal precipitate and extracellular biopolymer levels in the biofilm, and biofouling is significantly delayed when QQ is applied in addition to chlorine dosing. QQ with chlorine injection gives synergistic effects on reducing physically and chemically reversible fouling resistances while saving substantial filtration energy. Manipulating microbial community functions with chemical treatment is an attractive tool for biofilm dispersal in membrane bioreactors.

  7. Binding of dicamba to soluble and bound extracellular polymeric substances (EPS) from aerobic activated sludge: a fluorescence quenching study.

    Science.gov (United States)

    Pan, Xiangliang; Liu, Jing; Zhang, Daoyong; Chen, Xi; Song, Wenjuan; Wu, Fengchang

    2010-05-15

    Binding of dicamba to soluble EPS (SEPS) and bound EPS (BEPS) from aerobic activated sludge was investigated using fluorescence spectroscopy. Two protein-like fluorescence peaks (peak A with Ex/Em=225 nm/342-344 nm and peak B with Ex/Em=275/340-344 nm) were identified in SEPS and BEPS. Humic-like fluorescence peak C (Ex/Em=270-275 nm/450-460 nm) was only found in BEPS. Fluorescence of the peaks A and B for SEPS and peak A for BEPS were markedly quenched by dicamba at all temperatures whereas fluorescence of peaks B and C for BEPS was quenched only at 298 K. A dynamic process dominated the fluorescence quenching of peak A of both SEPS and BEPS. Fluorescence quenching of peak B and C was governed a static process. The effective quenching constants (logK(a)) were 4.725-5.293 for protein-like fluorophores of SEPS and 4.23-5.190 for protein-like fluorophores of BEPS, respectively. LogK(a) for humic-like substances was 3.85. Generally, SEPS had greater binding capacity for dicamba than BEPS, and protein-like substances bound dicamba more strongly than humic-like substances. Binding of dicamba to SEPS and BEPS was spontaneous and exothermic. Electrostatic force and hydrophobic interaction forces play a crucial role in binding of dicamba to EPS.

  8. O2(a1Δ) quenching in O/O2/O3/CO2/He/Ar mixtures

    Science.gov (United States)

    Azyazov, V. N.; Mikheyev, P. A.; Postell, D.; Heaven, M. C.

    2010-02-01

    The development of discharge singlet oxygen generators (DSOG's) that can operate at high pressures is required for the power scaling of the discharge oxygen iodine laser. In order to achieve efficient high-pressure DSOG operation it is important to understand the mechanisms by which singlet oxygen (O2(a1Δ)) is quenched in these devices. It has been proposed that three-body deactivation processes of the type O2(a1Δ))+O+M-->2O2+M provide significant energy loss channels. To further explore these reactions the physical and reactive quenching of O2(a1Δ)) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a1Δ)) quenching were followed by observing the 1268 nm fluorescence of the O2 a1Δ-X3Ε transition. Fast quenching of O2(a1Δ)) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

  9. Advanced oxidation of iodinated X-ray contrast media in reverse osmosis brines: the influence of quenching.

    Science.gov (United States)

    Azerrad, Sara P; Gur-Reznik, Shirra; Heller-Grossman, Lilly; Dosoretz, Carlos G

    2014-10-01

    Among the main restrictions for the implementation of advanced oxidation processes (AOPs) for removal of micropollutants present in reverse osmosis (RO) brines of secondary effluents account the quenching performed by background organic and inorganic constituents. Natural organic matter (NOM) and soluble microbial products (SMP) are the main effluent organic matter constituents. The inorganic fraction is largely constituted by chlorides and bicarbonate alkalinity with sodium and calcium as main counterions. The quenching influence of these components, separately and their mixture, in the transformation of model compounds by UVA/TiO2 was studied applying synthetic brines solutions mimicking 2-fold concentrated RO secondary effluents brines. The results were validated using fresh RO brines. Diatrizoate (DTZ) and iopromide (IOPr) were used as model compound. They have been found to exhibit relative high resistance to oxidation process and therefore represent good markers for AOPs techniques. Under the conditions applied, oxidization of DTZ in the background of RO brines was strongly affected by quenching effects. The major contribution to quenching resulted from organic matter (≈70%) followed by bicarbonate alkalinity (≈30%). NOM displayed higher quenching than SMP in spite of its relative lower concentration. Multivalent cations, i.e., Ca(+2), were found to decrease effectiveness of the technique due to agglomeration of the catalyst. However this influence was lowered in presence of NOM. Different patterns of transformation were found for each model compound in which a delayed deiodination was observed for iopromide whereas diatrizoate oxidation paralleled deiodination.

  10. Quenching parameter in a holographic thermal QCD

    Science.gov (United States)

    Patra, Binoy Krishna; Arya, Bhaskar

    2017-01-01

    We have calculated the quenching parameter, q ˆ in a model-independent way using the gauge-gravity duality. In earlier calculations, the geometry in the gravity side at finite temperature was usually taken as the pure AdS black hole metric for which the dual gauge theory becomes conformally invariant unlike QCD. Therefore we use a metric which incorporates the fundamental quarks by embedding the coincident D7 branes in the Klebanov-Tseytlin background and a finite temperature is switched on by inserting a black hole into the background, known as OKS-BH metric. Further inclusion of an additional UV cap to the metric prepares the dual gauge theory to run similar to thermal QCD. Moreover q ˆ is usually defined in the literature from the Glauber model perturbative QCD evaluation of the Wilson loop, which has no reasons to hold if the coupling is large and is thus against the main idea of gauge-gravity duality. Thus we use an appropriate definition of q ˆ : q ˆ L- = 1 /L2, where L is the separation for which the Wilson loop is equal to some specific value. The above two refinements cause q ˆ to vary with the temperature as T4 always and to depend linearly on the light-cone time L- with an additional (1 /L-) correction term in the short-distance limit whereas in the long-distance limit, q ˆ depends only linearly on L- with no correction term. These observations agree with other holographic calculations directly or indirectly.

  11. Quenching simulation of steel grinding balls

    Directory of Open Access Journals (Sweden)

    Zapata-Hernández, Oscar

    2015-09-01

    Full Text Available The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses.Las transformaciones de fase en aceros de alto carbono durante su temple y un posterior periodo de estabilización fueron modelizadas por medio del uso de paquetes computacionales basados en el método del elemento finito y de la transformación cinética de los aceros. El modelo se usó para predecir los cambios de temperatura y microestructura que se presentan en bolas de dos diferentes tamaños empleadas en estaciones de molienda de minerales. Se encontró una buena correlación entre las temperaturas medidas mediante la inserción de termopares y aquellas predichas por el modelo una vez que se modificó la conductividad térmica del acero en el intervalo mixto de fases. La predicción de las transformaciones de fase se confirmó a través del análisis metalográfico.

  12. Microstructural Characterization Of Quenched And Plastically Deformed Two-Phase α+β Titanium Alloys

    Directory of Open Access Journals (Sweden)

    Motyka M.

    2015-09-01

    Full Text Available Development of microstructure in two-phase α+β titanium alloys is realized by thermomechanical processing – sequence of heat treatment and plastic working operations. Analysis of achieved results indicates that hot plastic deformation – depending on deformation degree – causes significant elongation of α phase grains. Following heat treatment and plastic deformation processes lead to their fragmentation and spheroidization. Characterization of microstructure morphology changes during thermomechanical processing of quenched Ti-6Al-4V and Ti-6Al-2Mo-2Cr alloys is presented in the paper. The effect of martensitic phase α’(α” on microstructure development in plastic deformation process was confirmed.

  13. Carbonated aqueous media for quench heat treatment of steels

    Science.gov (United States)

    Nayak, U. Vignesh; Rao, K. M. Pranesh; Pai, M. Ashwin; Prabhu, K. Narayan

    2016-09-01

    Distilled water and polyalkylene glycol (PAG)-based aqueous quenchants of 5 and 10 vol.% with and without carbonation were prepared and used as heat transfer media during immersion quenching. Cooling curves were recorded during quenching of an inconel 600 cylindrical probe instrumented with multiple thermocouples. It was observed that the vapor stage duration was prolonged and the wetting front ascended uniformly for quenching with carbonated media. The cooling data were analyzed by determining the critical cooling parameters and by estimating the spatially dependent probe/quenchant interfacial heat flux transients. The study showed significantly reduced values of heat transfer rate for carbonated quenchants compared to quenchants without carbonation. Further, the reduction was more pronounced in the case of PAG-based carbonated quenchants than carbonated distilled water. The results also showed the dependence of heat transfer characteristics of the carbonated media on polymer concentration. The effect of quench uniformity on the microstructure of the material was assessed.

  14. Positronium quenching in liquid and solid octanol and benzene

    DEFF Research Database (Denmark)

    Shantarovich, V.P.; Mogensen, O.E.; Goldanskii, V.I.

    1970-01-01

    The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase....

  15. Organic synthesis by quench reactions. [in prebiotic simulation experiment

    Science.gov (United States)

    Park, W. K.; Hochstim, A. R.; Ponnamperuma, C.

    1975-01-01

    Study of the effects of chemical quench reactions on the formation of organic compounds at a water surface under simulated primordial earth conditions. A mixture of gaseous methane and ammonia over a water surface was exposed to an arc discharge between an electrode and the water surface, generating reactive species. Various organic molecules were formed by a subsequent quenching of these species generated on the water surface. The effects of these water-surface quench reactions were assessed by comparing the amounts of synthesized molecules to the amounts which formed during the discharge of an arc above the water level. It is concluded that the quench (or wet) discharge led to faster rates of reactions, higher-molecular-weight organic compounds, and one-order-of-magnitude larger yields than the dry discharge.

  16. Anthracene Fluorescence Quenching by a Tetrakis (Ketocarboxamide Cavitand

    Directory of Open Access Journals (Sweden)

    Tibor Zoltan Janosi

    2014-01-01

    Full Text Available Quenching of both fluorescence lifetime and fluorescence intensity of anthracene was investigated in the presence of a newly derived tetrakis (ketocarboxamide cavitand at various concentrations. Time-correlated single photon counting method was applied for the lifetime measurements. A clear correlation between the fluorescence lifetime of anthracene as a function of cavitand concentration in dimethylformamide solution was observed. The bimolecular collisional quenching constant was derived from the decrease of lifetime. Fluorescence intensity was measured in the emission wavelength region around 400 nm as a result of excitation at 280 nm. Effective quenching was observed in the presence of the cavitand. The obtained Stern-Volmer plot displayed upward curvature. The results did not follow even extended Stern-Volmer behavior, often used to describe deviations from static bimolecular quenching. To explain our results we adopted the Smoluchowski model and obtained a reasonable estimate for the molecular radius of the cavitand in solution.

  17. Measurement of cell volume changes by fluorescence self-quenching

    DEFF Research Database (Denmark)

    Hamann, Steffen; Kiilgaard, J.F.; Litman, Thomas

    2002-01-01

    At high concentrations, certain fluorophores undergo self-quenching, i.e., fluorescence intensity decreases with increasing fluorophore concentration. Accordingly, the self-quenching properties can be used for measuring water volume changes in lipid vesicles. In cells, quantitative determination...... of water transport using fluorescence self-quenching has been complicated by the requirement of relatively high (mM) and often toxic loading concentrations. Here we report a simple method that uses low (muM) loading concentrations of calcein-acetoxymethyl ester (calcein-AM) to obtain intracellular...... concentrations of the fluorophore calcein suitable for measurement of changes in cell water volume by self-quenching. The relationship between calcein fluorescence intensity, when excited at 490 nm (its excitation maximum), and calcein concentration was investigated in vitro and in various cultured cell types...

  18. Organic synthesis by quench reactions. [in prebiotic simulation experiment

    Science.gov (United States)

    Park, W. K.; Hochstim, A. R.; Ponnamperuma, C.

    1975-01-01

    Study of the effects of chemical quench reactions on the formation of organic compounds at a water surface under simulated primordial earth conditions. A mixture of gaseous methane and ammonia over a water surface was exposed to an arc discharge between an electrode and the water surface, generating reactive species. Various organic molecules were formed by a subsequent quenching of these species generated on the water surface. The effects of these water-surface quench reactions were assessed by comparing the amounts of synthesized molecules to the amounts which formed during the discharge of an arc above the water level. It is concluded that the quench (or wet) discharge led to faster rates of reactions, higher-molecular-weight organic compounds, and one-order-of-magnitude larger yields than the dry discharge.

  19. Quenched moderate deviations principle for random walk in random environment

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We derive a quenched moderate deviations principle for the one-dimensional nearest random walk in random environment,where the environment is assumed to be stationary and ergodic.The approach is based on hitting time decomposition.

  20. Reliability analysis for the quench detection in the LHC machine

    CERN Document Server

    Denz, R; Vergara-Fernández, A

    2002-01-01

    The Large Hadron Collider (LHC) will incorporate a large amount of superconducting elements that require protection in case of a quench. Key elements in the quench protection system are the electronic quench detectors. Their reliability will have an important impact on the down time as well as on the operational cost of the collider. The expected rates of both false and missed quenches have been computed for several redundant detection schemes. The developed model takes account of the maintainability of the system to optimise the frequency of foreseen checks, and evaluate their influence on the performance of different detection topologies. Seen the uncertainty of the failure rate of the components combined with the LHC tunnel environment, the study has been completed with a sensitivity analysis of the results. The chosen detection scheme and the maintainability strategy for each detector family are given.

  1. Research Progress of Gear Laser Quenching%齿轮激光淬火研究进展

    Institute of Scientific and Technical Information of China (English)

    王玉玲; 惠英龙; 姚翠翠

    2014-01-01

    This article summarized the research progress on the theories of laser quenching, and meanwhile analyzed the forma-tion mechanism of hardening layer, as well as its difference from the formation mechanism of the traditional gear quenching meth-ods. Through the analysis of scanning way, offset, scanning speed, angle of incidence and auxiliary cooling technology in the process of laser quenching, corresponding optimization schemes were put forward. By comparing the hardness of tooth surface, wear resistance, deformation, the microstructure and grain shape and distribution of the gears treated by laser quenching and normal quenching, it was concluded that the gear product of laser quenching had better mechanical performance than those prepared by the conventional quenching.%综述了齿轮激光淬火加工理论及方法的研究进展,分析了淬火硬化层形成机理以及与传统齿轮淬火硬化层形成机理的差异。通过对激光淬火加工的扫描方式、偏置量、扫描速度、入射角以及辅助冷却方式等工艺的分析,提出了相应的优化方案。对激光淬火和常规淬火后齿面的硬度、耐磨性、变形量、金相组织以及晶粒形状和分布进行了分析,认为齿轮激光淬火比常规淬火具备更优的机械性能。

  2. Entropy generation analysis for film boiling: A simple model of quenching

    Science.gov (United States)

    Lotfi, Ali; Lakzian, Esmail

    2016-04-01

    In this paper, quenching in high-temperature materials processing is modeled as a superheated isothermal flat plate. In these phenomena, a liquid flows over the highly superheated surfaces for cooling. So the surface and the liquid are separated by the vapor layer that is formed because of the liquid which is in contact with the superheated surface. This is named forced film boiling. As an objective, the distribution of the entropy generation in the laminar forced film boiling is obtained by similarity solution for the first time in the quenching processes. The PDE governing differential equations of the laminar film boiling including continuity, momentum, and energy are reduced to ODE ones, and a dimensionless equation for entropy generation inside the liquid boundary and vapor layer is obtained. Then the ODEs are solved by applying the 4th-order Runge-Kutta method with a shooting procedure. Moreover, the Bejan number is used as a design criterion parameter for a qualitative study about the rate of cooling and the effects of plate speed are studied in the quenching processes. It is observed that for high speed of the plate the rate of cooling (heat transfer) is more.

  3. An artificial neural network approach for ranking quenching parameters in central galaxies

    Science.gov (United States)

    Teimoorinia, Hossen; Bluck, Asa F. L.; Ellison, Sara L.

    2016-04-01

    We present a novel technique for ranking the relative importance of galaxy properties in the process of quenching star formation. Specifically, we develop an artificial neural network (ANN) approach for pattern recognition and apply it to a population of over 400 000 central galaxies taken from the Sloan Digital Sky Survey Data Release 7. We utilize a variety of physical galaxy properties for training the pattern recognition algorithm to recognize star-forming and passive systems, for a `training set' of ˜100 000 galaxies. We then apply the ANN model to a `verification set' of ˜100 000 different galaxies, randomly chosen from the remaining sample. The success rate of each parameter singly, and in conjunction with other parameters, is taken as an indication of how important the parameters are to the process(es) of central galaxy quenching. We find that central velocity dispersion, bulge mass and bulge-to-total stellar mass ratio are excellent predictors of the passive state of the system, indicating that properties related to the central mass of the galaxy are most closely linked to the cessation of star formation. Larger scale galaxy properties (total or disc stellar masses), or those linked to environment (halo masses or δ5), perform significantly less well. Our results are plausibly explained by AGN feedback driving the quenching of central galaxies, although we discuss other possibilities as well.

  4. Satellite quenching, Galaxy inner density and the halo environment

    Science.gov (United States)

    Woo, Joanna; Carollo, C. M.; Faber, S. M.; Dekel, Avishai; Tacchella, Sandro

    2017-01-01

    Using the Sloan Digital Sky Survey, we adopt the specific star formation rate (sSFR)-Σ*,1kpc diagram as a diagnostic tool to understand quenching in different environments. sSFR is the specific star formation rate and Σ*,1kpc is the stellar surface density in the inner kpc. Although both the host halo mass and group-centric distance affect the satellite population, we find that these can be characterized by a single number, the quenched fraction, such that key features of the sSFR-Σ*,1kpc diagram vary smoothly with this proxy for the `environment'. Particularly, the sSFR of star-forming galaxies decreases smoothly with this quenched fraction, the sSFR of satellites being 0.1 dex lower than in the field. Furthermore, Σ*,1kpc of the transition galaxies (i.e. the `green valley' or GV) decreases smoothly with the environment by as much as 0.2 dex for M* = 109.75-10 from the field, and decreasing for satellites in larger haloes and at smaller radial distances within same-mass haloes. We interpret this shift as indicating the relative importance of today's field quenching track versus the cluster quenching track. These environmental effects in the sSFR-Σ*,1kpc diagram are most significant in our lowest mass range (9.75 < log M*/M⊙ < 10). One feature that is shared between all environments is that at a given M*, quenched galaxies have about 0.2-0.3 dex higher Σ*,1kpc than the star-forming population. These results indicate that either Σ*,1kpc increases (subsequent to satellite quenching), or Σ*,1kpc for individual galaxies remains unchanged, but the original M* or the time of quenching is significantly different from those now in the GV.

  5. Oxygen quenching in LAB based liquid scintillator and nitrogen bubbling

    CERN Document Server

    Hua-Lin, Xiao

    2009-01-01

    Oxygen quenching effect in Linear Alkl Benzne (LAB) based liquid scintillator (LAB+3g/L POPOP+ 15 mg Bis--MSB) was studied by measuring the light yield as the function of nitrogen bubbling time. it shows that the light yield of fully purged liquid scintillator would increase of nearly 11% in room temperature and room atmosphere pressure. A simple model of nitrogen bubbling was built to describe the relationship between relative light yield (oxygen quenching factor) and bubbling time.

  6. First experience with the new Coupling Loss Induced Quench system

    CERN Document Server

    Ravaioli, E; Dudarev, A V; Kirby, G; Sperin, K A; ten Kate, H H J; Verweij, A P

    2014-01-01

    New-generation high-field superconducting magnets pose a challenge relating to the protection of the coil winding pack in the case of a quench. The high stored energy per unit volume calls for a very efficient quench detection and fast quench propagation in order to avoid damage due to overheating. A new protection system called Coupling-Loss Induced Quench (CLIQ) was recently, developed and tested at CERN. This method provokes a fast change in the magnet transport current by means of a capacitive discharge. The resulting change in the local magnetic field induces inter-filament and inter-strand coupling losses which heat up the superconductor and eventually initiate a quench in a large fraction of the coil winding pack. The method is extensively tested on a Nb-Ti single-wire test solenoid magnet in the CERN Cryogenic Laboratory in order to assess its performance, optimize its operating parameters, and study new electrical configurations. Each parameter is thoroughly analyzed and its impact on the quench effi...

  7. Smooth and fast versus instantaneous quenches in quantum field theory

    CERN Document Server

    Das, Sumit R; Myers, Robert C

    2015-01-01

    We examine in detail the relationship between smooth fast quantum quenches, characterized by a time scale $\\delta t$, and instantaneous quenches, within the framework of exactly solvable mass quenches in free scalar field theory. We study UV finite quantities like correlators at finite spatial distances and the excess energy produced above the final ground state energy. We show that at late times and large distances (compared to the quench time scale) the correlator approaches the instantaneous quench correlator. At early times, we find that for small spatial separation and small $\\delta t$, the correlator scales universally with $\\delta t$, exactly as in the scaling of renormalized one point functions found in earlier work. At larger separation, the dependence on $\\delta t$ drops out. The excess energy also scales in a universal fashion: in the $m\\delta t \\rightarrow0$ limit it is finite for $d \\leq 3$ and agrees with the instantaneous quench, while it is divergent in higher dimensions. We argue that similar...

  8. Thermal quenching of thermoluminescence in quartz samples of various origin

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, B. [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124-Thessaloniki (Greece); Oniya, E. [Archaeometry Laboratory, Cultural and Educational Technology Institute (C.E.T.I.), R.C. ' Athena' , Tsimiski 58, 67100 Xanthi (Greece); Physics and Electronics Department, Adekunle Ajasin University, PMB 01, Akungba Akoko (Nigeria); Polymeris, G.S. [ISIK University, Physics Department, Faculty of Science and Arts, 34980-Sile, Istanbul (Turkey); Afouxenidis, D.; Tsirliganis, N.C. [Archaeometry Laboratory, Cultural and Educational Technology Institute (C.E.T.I.), R.C. ' Athena' , Tsimiski 58, 67100 Xanthi (Greece); Kitis, G., E-mail: gkitis@auth.g [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124-Thessaloniki (Greece)

    2011-03-15

    The effect of thermal quenching stands among the most important properties in the thermoluminescence (TL) of quartz on which many applications of TL are based. Since the quartz samples used in various applications are all of different origin it is useful to investigate whether the values of the thermal quenching parameters, i.e. the activation energy for thermal quenching W and a parameter C which describes the ratio of non-radiative to radiative luminescence transitions, evaluated mainly in specific quartz samples can be extrapolated to quartz samples of unknown origin as well as to quartz samples which are annealed at high temperatures. In the present work the TL glow curve of a series of un-annealed and annealed natural and synthetic quartz samples were studied as a function of the heating rate between 0.25 K/s and 16 K/s. Using an indirect fitting method it was found that the thermal quenching parameters W and C in most of the quartz samples are very similar to the values accepted in the literature. Furthermore, in some cases the thermal quenching parameters W and C are not the same for all TL glow-peaks in the same glow-curve. Finally, the strong external treatment of annealing the quartz samples at very high temperature can also influence at least one of the thermal quenching parameters.

  9. New Fast Response Thin Film-Based Superconducting Quench Detectors

    CERN Document Server

    Dudarev, A; van de Camp, W; Ravaioli, E; Teixeira, A; ten Kate, H H J

    2014-01-01

    Quench detection on superconducting bus bars and other devices with a low normal zone propagation velocity and low voltage build-up is quite difficult with conventional quench detection techniques. Currently, on ATLAS superconducting bus bar sections, superconducting quench detectors (SQD) are mounted to detect quench events. A first version of the SQD essentially consists of an insulated superconducting wire glued to a superconducting bus line or windings, which in the case of a quench rapidly builds up a relatively high resistance that can be easily and quietly detected. We now introduce a new generation of drastically improved SQDs. The new version makes the detection of quenches simpler, more reliable, and much faster. Instead of a superconducting wire, now a superconducting thin film is used. The layout of the sensor shows a meander like pattern that is etched out of a copper coated 25 mu m thick film of Nb-Ti glued in between layers of Kapton. Since the sensor is now much smaller and thinner, it is easi...

  10. Ultracold Rotational Quenching Study of CO with H+

    Science.gov (United States)

    Kaur, Rajwant; Kumar, T. J. Dhilip

    2016-05-01

    Cooling and trapping of polar molecules have stimulated research in precise monitoring and controlling dynamics in ultracold regime. There has been considerable interest in the study of molecular inelastic collision processes at cold and ultracold temperatures. Collisional study of polar interstellar species CO, adds an additional astrophysical importance to model interstellar medium. Present work focuses on rotational quenching of abundant interstellar species, CO with H+ using quantum-mechanical scattering calculation. Rate coefficients for molecular rotational transitions of CO due to collision with H+ are obtained in the range of 10-5 K to 200 K from cross sections which are computed using close coupling calculations as implemented in MOLSCAT. The data generated from ultracold to higher temperatures assist in investigating the chemistry of interstellar clouds. Calculations are performed on ground state ab initio potential energy surface using MRCI/cc-pVTZ method. Rotational transitions are studied in the rigid-rotor approximation with CO bond length fixed at an equilibrium value of 2.138 a.u. Asymptotic potentials are computed using the dipole and quadrupole moments, and the dipole polarizability components.

  11. Entanglement Growth in Quench Dynamics with Variable Range Interactions

    Directory of Open Access Journals (Sweden)

    J. Schachenmayer

    2013-09-01

    Full Text Available Studying entanglement growth in quantum dynamics provides both insight into the underlying microscopic processes and information about the complexity of the quantum states, which is related to the efficiency of simulations on classical computers. Recently, experiments with trapped ions, polar molecules, and Rydberg excitations have provided new opportunities to observe dynamics with long-range interactions. We explore nonequilibrium coherent dynamics after a quantum quench in such systems, identifying qualitatively different behavior as the exponent of algebraically decaying spin-spin interactions in a transverse Ising chain is varied. Computing the buildup of bipartite entanglement as well as mutual information between distant spins, we identify linear growth of entanglement entropy corresponding to propagation of quasiparticles for shorter-range interactions, with the maximum rate of growth occurring when the Hamiltonian parameters match those for the quantum phase transition. Counterintuitively, the growth of bipartite entanglement for long-range interactions is only logarithmic for most regimes, i.e., substantially slower than for shorter-range interactions. Experiments with trapped ions allow for the realization of this system with a tunable interaction range, and we show that the different phenomena are robust for finite system sizes and in the presence of noise. These results can act as a direct guide for the generation of large-scale entanglement in such experiments, towards a regime where the entanglement growth can render existing classical simulations inefficient.

  12. Eigenvalue tunneling and decay of quenched random network

    Science.gov (United States)

    Avetisov, V.; Hovhannisyan, M.; Gorsky, A.; Nechaev, S.; Tamm, M.; Valba, O.

    2016-12-01

    We consider the canonical ensemble of N -vertex Erdős-Rényi (ER) random topological graphs with quenched vertex degree, and with fugacity μ for each closed triple of bonds. We claim complete defragmentation of large-N graphs into the collection of [p-1] almost full subgraphs (cliques) above critical fugacity, μc, where p is the ER bond formation probability. Evolution of the spectral density, ρ (λ ) , of the adjacency matrix with increasing μ leads to the formation of a multizonal support for μ >μc . Eigenvalue tunneling from the central zone to the side one means formation of a new clique in the defragmentation process. The adjacency matrix of the network ground state has a block-diagonal form, where the number of vertices in blocks fluctuates around the mean value N p . The spectral density of the whole network in this regime has triangular shape. We interpret the phenomena from the viewpoint of the conventional random matrix model and speculate about possible physical applications.

  13. Eigenvalue tunnelling and decay of quenched random networks

    CERN Document Server

    Avetisov, V; Gorsky, A; Nechaev, S; Tamm, M; Valba, O

    2016-01-01

    We consider the canonical ensemble of Erd\\H{o}s-R\\'enyi (ER) random graphs with quenched vertex degree, and with fugacity $\\mu$ for each closed triple of bonds. We claim complete defragmentation of large-$N$ topological graphs into the collection of $[p^{-1}]$ almost full subgraphs (cliques) above critical fugacity, $\\mu_c$, where $p$ is the ER bond formation probability. Evolution of the spectral density, $\\rho(\\lambda)$, of the adjacency matrix with increasing $\\mu$ leads to the formation of two-zonal support above some critical point $\\mu_c$. Eigenvalue tunnelling from one (central) zone to the other means formation of a new clique in the defragmentation process. The symmetry of clusterized network breaks down from $U(N)$ to $U([p^{-1}])\\times U(N-[p^{-1}])$ and the spectral density of the whole network in this regime has triangular shape. We interpret the phenomena from the viewpoint of the conventional random matrix model and speculate about possible physical applications.

  14. Enhanced quench propagation in 2G-HTS coils co-wound with stainless steel or anodised aluminium tapes

    Science.gov (United States)

    Núñez-Chico, A. B.; Martínez, E.; Angurel, L. A.; Navarro, R.

    2016-08-01

    Early quench detection and thermal stability of superconducting coils are of great relevance for practical applications. Magnets made with second generation high temperature superconducting (2G-HTS) tapes present low quench propagation velocities and therefore slow voltage development and high local temperature rises, which may cause irreversible damage. Since quench propagation depends on the anisotropy of the thermal conductivity, this may be used to achieve an improvement of the thermal stability and robustness of 2G-HTS coils. On pancake type coils, the thermal conductivity along the tapes (coil’s azimuthal direction) is mostly fixed by the 2G-HTS tape characteristics, so that the reduction of anisotropy relies on the improvement of the radial thermal conductivity, which depends on the used materials between superconducting tapes, as well as on the winding and impregnation processes. In this contribution, we have explored two possibilities for such anisotropy reduction: by using anodised aluminium or stainless steel tapes co-wound with the 2G-HTS tapes. For all the analysed coils, critical current distribution, minimum quench energy values and both tangential and radial quench propagation velocities at different temperatures and currents are reported and compared with the results of similar coils co-wound with polyimide (Kapton®) tapes.

  15. On improving the performance of nonphotochemical quenching in CP29 light-harvesting antenna complex

    Energy Technology Data Exchange (ETDEWEB)

    Berman, Gennady P. [Theoretical Division, T-4, Los Alamos National Laboratory, and the New Mexico Consortium, Los Alamos, NM 87544 (United States); Nesterov, Alexander I., E-mail: nesterov@cencar.udg.mx [Departamento de Física, CUCEI, Universidad de Guadalajara, Av. Revolución 1500, Guadalajara, CP 44420, Jalisco (Mexico); Sayre, Richard T. [Biological Division, B-11, Los Alamos National Laboratory, and the New Mexico Consortium, Los Alamos, NM 87544 (United States); Still, Susanne [Department of Information and Computer Sciences, and Department of Physics and Astronomy, University of Hawaii at Mānoa, 1860 East–West Road, Honolulu, HI 96822 (United States)

    2016-03-22

    We model and simulate the performance of charge-transfer in nonphotochemical quenching (NPQ) in the CP29 light-harvesting antenna-complex associated with photosystem II (PSII). The model consists of five discrete excitonic energy states and two sinks, responsible for the potentially damaging processes and charge-transfer channels, respectively. We demonstrate that by varying (i) the parameters of the chlorophyll-based dimer, (ii) the resonant properties of the protein-solvent environment interaction, and (iii) the energy transfer rates to the sinks, one can significantly improve the performance of the NPQ. Our analysis suggests strategies for improving the performance of the NPQ in response to environmental changes, and may stimulate experimental verification. - Highlights: • Improvement of the efficiency of the charge-transfer nonphotochemical quenching in CP29. • Strategy for restoring the NPQ efficiency when the environment changes. • By changing of energy transfer rates to the sinks, one can significantly improve the performance of the NPQ.

  16. Influence of isothermal quenching of LAMC CrMnSi cast steel on impact toughness

    Institute of Scientific and Technical Information of China (English)

    JIN Bao-shi; HUANG Zhi-qiu; SHEN Da-dong

    2005-01-01

    The influence of isothermal quenching process of low-alloy and medium carbon (LAMC) CrMnSi cast steel on the impact toughness was investigated. The microstructure and mechanical property of LAMC CrMnSi cast steel were analyzed by the laser optical modulator, the scanning electron microscopy, the energy dispersive spectrometer, the hardness and impact tests. The experimental results show that the dual phases of bainite and residual austenite can be obtained by the severity isothermal quenching, the fractographies of specimens change from quasi-cleavage to dimple at 310 ℃ for 60 min, the impact toughness for specimens at the room temperature isothermally achieves 130 J/cm2, meantime and its hardness is more than 45(HRC).

  17. Reduction of Concentration Quenching in a Nondoped DCM Organic Light-Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-Gang; CHEN Zhi-Jian; GONG Qi-Huang

    2005-01-01

    @@ We obtain a nondoped red organic light-emitting diode (OLED) structure ITO/pc-PPV (~30 nm)/DCM (~30 nm)/BCP (~30nm)/Mg:Ag, where DCM refers to 4-(dicyanomethylene)-2-methyl-6-[(4-dimethylaninostyryl)-4-H-pyran]. The OLED shows pure and stable red luminescence depending on the driving voltages. The maximum luminance is 330 Cd/m2 and the turn-on voltage is as low as ~2 V. The reason why the concentration quenching of DCM could be reduced in this structure is investigated. In the preparation process, both the hole-transporting layer and the emitter layer are formed by the spin-coated method. It is believed that this method can lead to a new way to avoid the concentration quenching of red-emitting materials.

  18. Effect of Biosynthesized Silver Nanoparticles on Staphylococcus aureus Biofilm Quenching and Prevention of Biofilm Formation

    Institute of Scientific and Technical Information of China (English)

    Pratik R. Chaudhari∗; Shalaka A. Masurkar; Vrishali B. Shidore; Suresh P. Kamble

    2012-01-01

    The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and 1 mM silver nitrate. 100 mM glucose was found to quicken the rate of reaction of silver nanoparticles synthesis. UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesized silver nanoparticles were further characterized by using Nanoparticle Tracking Analyzer (NTA), Transmission Electron Microscope and Energy Dispersive X-ray spectra. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope (40 X). The synergistic effect of silver nanoparticles along with antibiotics in biofilm quenching was found to be effective. In the near future, silver nanoparticles could be used in the treatment of infections caused by highly antibiotic resistant biofilm.

  19. Quench-condensing superconducting thin films using the Fab on a Chip approach

    Science.gov (United States)

    Han, Han; Imboden, Matthias; Del Corro, Pablo; Stark, Thomas; Lally, Richard; Pardo, Flavio; Bolle, Cristian; Bishop, David

    Micro-electromechanical systems (MEMS) being manufactured in a macroscopic fab inspires the idea of getting the process further down to fabricate even smaller structures, namely nano-structures, using MEMS. The Fab on a Chip concept was proposed based on such ideas. By implementing the final-step, additive fabrication approach, manufacturing, characterization and experiments of nano-structures are integrated in-situ. Due to the miniature size of MEMS, the thickness precision is significantly improved while the power consumption is significantly depressed, making the quench-condensation of very thin films well controlled and easily achievable. Among various types of nano-structures, quench-condensed superconducting thin films are of great interest for physicists. Here we present such experiments done on superconducting thin films quench-condensed using the Fab on a Chip. We show that we are able to fabricate very thin films with its thickness precisely controlled, and the base temperature kept under ~3K during the process. The resistivity data demonstrates the high purity and uniformity of the film, as well as the annealing effect when cycling to higher temperatures. Based on the tremendous results obtained from the superconducting thin films, more complex nano-circuits can be fabricated and investigated using the Fab on a Chip, enabling a new approach for novel condensed matter physics experiments. This research is funded by the NSF through their CMMI division. This research is funded by the NSF through their CMMI division.

  20. Rotational Quenching Study in Isovalent H+ + CO and H+ + CS Systems

    Science.gov (United States)

    Kaur, Rajwant; Dhilip Kumar, T. J.

    2016-06-01

    Cooling and trapping of polar molecules has attracted attention at cold and ultracold temperatures. Extended study of molecular inelastic collision processes of polar interstellar species with proton finds an important astrophysical application to model interstellar medium. Present study includes computation of rate coefficient for molecular rotational quenching process in proton collision with isovalent CO and CS molecules using quantum dynamical close-coupling calculations. Full dimensional ab initio potential energy surfaces have been computed for the ground state for both the systems using internally contracted multireference configuration interaction method and basis sets. Quantum scattering calculations for rotational quenching of isovalent species are studied in the rigid-rotor approximation with CX (X=O, S) bond length fixed at an experimental equilibrium value of 2.138 and 2.900 a.u., respectively. Asymptotic potentials are computed using the dipole and quadrupole moments, and the dipole polarizability components. The resulting long-range potentials with the short-range ab initio interaction potentials have been fitted to study the anisotropy of the rigid-rotor surface using the multipolar expansion coefficients. Rotational quenching cross-section and corresponding rates from j=4 level of CX to lower j' levels have been obtained and found to obey Wigner's threshold law at ultra cold temperatures.

  1. An Intelligent Optical Dissolved Oxygen Measurement Method Based on a Fluorescent Quenching Mechanism

    Directory of Open Access Journals (Sweden)

    Fengmei Li

    2015-12-01

    Full Text Available Dissolved oxygen (DO is a key factor that influences the healthy growth of fishes in aquaculture. The DO content changes with the aquatic environment and should therefore be monitored online. However, traditional measurement methods, such as iodometry and other chemical analysis methods, are not suitable for online monitoring. The Clark method is not stable enough for extended periods of monitoring. To solve these problems, this paper proposes an intelligent DO measurement method based on the fluorescence quenching mechanism. The measurement system is composed of fluorescent quenching detection, signal conditioning, intelligent processing, and power supply modules. The optical probe adopts the fluorescent quenching mechanism to detect the DO content and solves the problem, whereas traditional chemical methods are easily influenced by the environment. The optical probe contains a thermistor and dual excitation sources to isolate visible parasitic light and execute a compensation strategy. The intelligent processing module adopts the IEEE 1451.2 standard and realizes intelligent compensation. Experimental results show that the optical measurement method is stable, accurate, and suitable for online DO monitoring in aquaculture applications.

  2. Monolithic active quenching and picosecond timing circuit suitable for large-area single-photon avalanche diodes.

    Science.gov (United States)

    Gallivanoni, A; Rech, I; Resnati, D; Ghioni, M; Cova, S

    2006-06-12

    A new integrated active quenching circuit (i-AQC) designed in a standard CMOS process is presented, capable of operating with any available single photon avalanche diode (SPAD) over wide temperature range. The circuit is suitable for attaining high photon timing resolution also with wide-area SPADs. The new i-AQC integrates the basic active-quenching loop, a patented low-side timing circuit comprising a fast pulse pick-up scheme that substantially improves time-jitter performance, and a novel active-load passive quenching mechanism (consisting of a current mirror rather than a traditional high-value resistor) greatly improves the maximum counting rate. The circuit is also suitable for portable instruments, miniaturized detector modules and SPAD-array detectors. The overall features of the circuit may open the way to new developments in diversified applications of time-correlated photon counting in life sciences and material sciences.

  3. Effect of Quenching Parameters on Mechanical Property of Ultra High Strength Steel BR1500HS Based on Response Surface Methodology

    Institute of Scientific and Technical Information of China (English)

    Jie Zhou; Zhi-Yong Huang; Lei Lin; Shi-Yun Li

    2014-01-01

    Hot stamping of high strength steels is defined as a process in which blank is heated to the temperature of the austenite stabilization region for a definite time and then formed and quenched simultaneously in a mold with cooling channels. During this process, the processing parameters of austenite temperature and soaking time have strong effects on the mechanical properties such as quenching hardness, tensile strength and elongation. Hence, it is necessary to investigate the relationship between the mechanical properties and the two processing parameters. In this paper, the orthogonal experiment with two factors and five levels was applied, and the experimental data based on the orthogonal experiment was acquired. Based on the data, regression models were set up and the results of the analysis of variance ( ANOVA) showed that it is reliable to predict the quenching hardness, tensile strength and elongation by the regression models. Besides, the optimal results of each single object were obtained based on response surface methodology ( RSM ) , and global optimums was gained by employing ideal point method in which the quenching hardness, and tensile strength and elongation were considered simultaneously.

  4. Quenching of the Alpha Effect in Dynamo Theory

    CERN Document Server

    Field, G B; Field, George B.; Blackman, Eric G.

    2002-01-01

    We use the formalism of Pouquet, Frisch and L\\'eorat (hereafter PFL, 1976) to investigate time dependent quenching of $\\alpha$ in mean field dynamo theory for a closed system. Quenching occurs as the result of an $\\alpha$ induced flow of magnetic helicity from small to large scales. Our results agree reasonably well with with the numerical simulations of Brandenburg (2001ab). Gruzinov and Diamond (hereafter GD, 1994, 1995, 1996) and Bhattacharjee and Yuan (hereafter BY, 1995) also used the conservation of magnetic helicity to argue that $\\alpha$ in a closed steady-state system is quenched for strongly sub-equipartition mean field strengths. Taken at face value, we find that the GD and BY results need to be reinterpreted when time dependence and turbulent diffusivity are included; then, quenching occurs only when the mean field reaches near equipartition. In the special case where the scale of the mean field is infinite, the lack of turbulent diffusion leads to resistive quenching of $\\alpha$ at asymptotically...

  5. Plasmonic Molecular Nanohybrids—Spectral Dependence of Fluorescence Quenching

    Directory of Open Access Journals (Sweden)

    Maria Olejnik

    2012-01-01

    Full Text Available We demonstrate strong spectral dependence of the efficiency of fluorescence quenching in molecular systems composed of organic dyes and gold nanoparticles. In order to probe the coupling with metallic nanoparticles we use dyes with varied spectral overlap between the plasmon resonance and their absorption. Hybrid molecular structures were obtained via conjugation of metallic nanoparticles with the dyes using biotin-streptavidin linkage. For dyes featuring absorption above the plasmon excitation in gold nanoparticles, laser excitation induces minute changes in the fluorescence intensity and its lifetime for both conjugated and non-conjugated mixtures, which are the reference. In contrast, when the absorption of the dye overlaps with the plasmon resonance, the effect is quite dramatic, reaching 85% and 95% fluorescence quenching for non-conjugated and conjugated mixtures, respectively. The degree of fluorescence quenching strongly depends upon the concentration of metallic nanoparticles. Importantly, the origin of the fluorescence quenching is different in the case of the conjugated mixture, as evidenced by time-resolved fluorescence. For conjugated mixtures of dyes resonant with plasmon, excitation features two-exponential decay. This is in contrast to the single exponential decay measured for the off-resonant configuration. The results provide valuable insight into spectral dependence of the fluorescence quenching in molecular assemblies involving organic dyes and metallic nanoparticles.

  6. A Dichotomy in Satellite Quenching Around L* Galaxies

    CERN Document Server

    Phillips, John I; Boylan-Kolchin, Michael; Bullock, James S; Cooper, Michael C; Tollerud, Erik J

    2013-01-01

    We examine the star formation properties of bright (~0.1 L*) satellites around isolated ~L* hosts in the local Universe using spectroscopically confirmed systems in the Sloan Digital Sky Survey DR7. Our selection method is carefully designed with the aid of N-body simulations to avoid groups and clusters. We find that satellites are significantly more likely to be quenched than a stellar mass-matched sample of isolated galaxies. Remarkably, this quenching occurs only for satellites of hosts that are themselves quenched: while star formation is unaffected in the satellites of star-forming hosts, satellites around quiescent hosts are more than twice as likely to be quenched than stellar-mass matched field samples. One implication of this is that whatever shuts down star formation in isolated, passive L* galaxies also plays at least an indirect role in quenching star formation in their bright satellites. The previously-reported tendency for "galactic conformity" in color/morphology may be a by-product of this ho...

  7. Testing beam-induced quench levels of LHC superconducting magnets

    Science.gov (United States)

    Auchmann, B.; Baer, T.; Bednarek, M.; Bellodi, G.; Bracco, C.; Bruce, R.; Cerutti, F.; Chetvertkova, V.; Dehning, B.; Granieri, P. P.; Hofle, W.; Holzer, E. B.; Lechner, A.; Nebot Del Busto, E.; Priebe, A.; Redaelli, S.; Salvachua, B.; Sapinski, M.; Schmidt, R.; Shetty, N.; Skordis, E.; Solfaroli, M.; Steckert, J.; Valuch, D.; Verweij, A.; Wenninger, J.; Wollmann, D.; Zerlauth, M.

    2015-06-01

    In the years 2009-2013 the Large Hadron Collider (LHC) has been operated with the top beam energies of 3.5 and 4 TeV per proton (from 2012) instead of the nominal 7 TeV. The currents in the superconducting magnets were reduced accordingly. To date only seventeen beam-induced quenches have occurred; eight of them during specially designed quench tests, the others during injection. There has not been a single beam-induced quench during normal collider operation with stored beam. The conditions, however, are expected to become much more challenging after the long LHC shutdown. The magnets will be operating at near nominal currents, and in the presence of high energy and high intensity beams with a stored energy of up to 362 MJ per beam. In this paper we summarize our efforts to understand the quench levels of LHC superconducting magnets. We describe beam-loss events and dedicated experiments with beam, as well as the simulation methods used to reproduce the observable signals. The simulated energy deposition in the coils is compared to the quench levels predicted by electrothermal models, thus allowing one to validate and improve the models which are used to set beam-dump thresholds on beam-loss monitors for run 2.

  8. Spectral analysis of colour-quenched and chemically quenched C-14 samples; Estudio espectral de muestras de C-14 con extincion quimica y por color en centelleo liquido

    Energy Technology Data Exchange (ETDEWEB)

    Scott, P. E.; Grau, A.

    1987-07-01

    In this paper pairs of pulse height distribution curves, of C-14 samples, colour-quenched and chemically quenched was obtained. The possibility to choose a counting window in order to obtain the counting efficiency curves, for both type of quenching was studied. (Author) 7 refs.

  9. Evolution of Density Profiles in High-z Galaxies: Compaction and Quenching Inside-Out

    CERN Document Server

    Tacchella, Sandro; Carollo, C Marcella; Ceverino, Daniel; DeGraf, Colin; Lapiner, Sharon; Mandelker, Nir; Primack, Joel R

    2015-01-01

    Using cosmological simulations, we address the interplay between structure and star formation in high-redshift galaxies via the evolution of surface density profiles. Our sample consists of 26 galaxies evolving in the redshift range $z=7-1$, spanning the stellar mass range $(0.2-6.4)\\times 10^{10}M_\\odot$ at $z=2$. We recover the main trends by stacking the profiles in accordance to their evolution phases. Following a wet compaction event that typically occurs when the stellar mass is $\\sim10^{9.5}~M_{\\odot}$ at $z\\sim2-4$, the gas develops a cusp inside the effective radius, associated with a peak in star-formation rate (SFR). The SFR peak and the associated feedback, in the absence of further gas inflow to the centre, marks the onset of gas depletion from the central 1 kpc, leading to quenching of the central SFR. An extended, star-forming ring that forms by fresh gas during the central quenching process shows as a rising specific SFR (sSFR) profile, which is interpreted as inside-out quenching. Before quen...

  10. Development of a carburizing and quenching simulation tool: numerical simulations of rings and gears

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, C.; Godlman, P.; Rangaswamy, P. [and others

    1996-10-01

    The ability to accurately calculate temperatures, stresses and metallurgical transformations in a single calculation or in a sequence of calculations is the key to prediction of distortion, residual stress and phase distribution in quench hardened automotive parts. Successful predictions in turn rely on the adequacy of the input data to the calculational procedure. These data include mechanical and thermal properties of the alloy phases over the range of temperature and strain rates experienced during the heat treat process, the mathematical description of the transformation kinetics, and the accuracy of the heat transfer boundary conditions. In this presentation we describe a calculational procedure using the ABAQUS{sup (1)} finite element code that simulates a carburizing and quench heat treat cycle for automotive gears. The calculational procedure features a numerically efficient 2-phase constitutive model, developed as part of the NCMS-Heat Treatment Distortion Prediction program, to represent transformational plasticity effects for the austenite/martensite Deformation together with refined finite element meshes to capture the steep gradients in stress and composition near the gear surfaces. The calculational procedure is illustrated on carburizing and quenching of a thick ring and comparison of model predictions for distortion, phase distribution, and residual stress with experimental measurements are discussed. Included in this model study is an investigation of the sensitivity of the predictions to mesh refinement.

  11. Inhibition of Biofilm Formation by T7 Bacteriophages Producing Quorum-Quenching Enzymes

    Science.gov (United States)

    Lamas-Samanamud, Gisella R.

    2014-01-01

    Bacterial growth in biofilms is the major cause of recalcitrant biofouling in industrial processes and of persistent infections in clinical settings. The use of bacteriophage treatment to lyse bacteria in biofilms has attracted growing interest. In particular, many natural or engineered phages produce depolymerases to degrade polysaccharides in the biofilm matrix and allow access to host bacteria. However, the phage-produced depolymerases are highly specific for only the host-derived polysaccharides and may have limited effects on natural multispecies biofilms. In this study, an engineered T7 bacteriophage was constructed to encode a lactonase enzyme with broad-range activity for quenching of quorum sensing, a form of bacterial cell-cell communication via small chemical molecules (acyl homoserine lactones [AHLs]) that is necessary for biofilm formation. Our results demonstrated that the engineered T7 phage expressed the AiiA lactonase to effectively degrade AHLs from many bacteria. Addition of the engineered T7 phage to mixed-species biofilms containing Pseudomonas aeruginosa and Escherichia coli resulted in inhibition of biofilm formation. Such quorum-quenching phages that can lyse host bacteria and express quorum-quenching enzymes to affect diverse bacteria in biofilm communities may become novel antifouling and antibiofilm agents in industrial and clinical settings. PMID:24951790

  12. Temperature Dependence of Nitro-Quenching by Atmospheric-Pressure Plasma

    Science.gov (United States)

    Mitani, Masaki; Ichiki, Ryuta; Iwakiri, Yutaro; Akamine, Shuichi; Kanazawa, Seiji

    2015-09-01

    A lot of techniques exist as the hardening method of steels, such as nitriding, carburizing and quenching. However, low-alloy steels cannot be hardened by nitriding because hardening by nitriding requires nitride precipitates of special alloy elements such as rare metals. Recently, nitro-quenching (NQ) was developed as a new hardening process, where nitrogen invokes martensitic transformation instead of carbon. NQ is adaptable to hardening low-alloy steels because it does not require alloy elements. In industrial NQ, nitrogen diffusion into steel surface is operated in high temperature ammonia gas. As a new technology, we have developed surface hardening of low-alloy steel by NQ using an atmospheric-pressure plasma. Here the pulsed-arc plasma jet with nitrogen/hydrogen gas mixture is sprayed onto steel surface and then water quench the sample. As a result, the surface of low-alloy steel was partially hardened up to 800 Hv by producing iron-nitrogen martensite. However, the hardness profile is considerably non-uniform. We found that the non-uniform hardness profile can be controlled by changing the treatment gap, the gap between the jet nozzle and the sample surface. Eventually, we succeeded in hardening a targeted part of steel by optimizing the treatment gap. Moreover, we propose the mechanism of non-uniform hardness.

  13. Quench propagation and detection in the superconducting bus-bars of the ATLAS magnets

    CERN Document Server

    Dudarev, A; ten Kate, H H J; Sbrissa, E; Yamamoto, A; Baynham, D Elwyn; Courthold, M J D; Lesmond, C

    2000-01-01

    The ATLAS superconducting magnet system comprising Barrel (BT) and End-Cap Toroids (ECT) and also Central Solenoid (CS) will store more than 1.5 GJ of magnetic energy. The magnet system will have many superconducting busbars, a few meters long each, running from the current leads to Central Solenoid and Toroids as well as between the coils of each Toroid. Quench development in the busbars, i.e., the normal zone propagation process along the busbar superconductors, is slow and exhibits very low voltages. Therefore, its timely and appropriate detection represents a real challenge. The temperature evolution in the busbars under quench is of primary importance. Conservative calculations of the temperature were performed for all the magnets. Also, a simple and effective method to detect a normal zone in a busbar is presented. A thin superconducting wire, whose normal resistance can be easily detected, is placed in a good thermal contact to busbar. Thus, the wire can operate as straightforward and low-noise quench-...

  14. Fire prevention for oil quenching%用油淬火的火灾防治

    Institute of Scientific and Technical Information of China (English)

    陈春怀; 周敬恩

    2001-01-01

    Due to its slower cooling rate at convection stage,Oil is still a dominant quenchants for alloy steel quenching. However,the danger of the fire hazards does exist in this quenching process,which not only cause enormously economic losses,but also has impact on environment and safety in production. With the view of production safety and stability of quenching quality,this paper firstly analyzes the possible reasons to the fire hazards,then gives detailed discussions for remedial actions.%现在不时仍有因淬火油使用不当而发生的火灾事故和惨剧,这不仅造成了巨大的经济损失,而且对环境和安全生产构成了巨大威胁。对使用淬火油可能产生火灾事故的原因进行了分析,提出了应对措施和建议。

  15. Quenching vs. Quiescence: forming realistic massive ellipticals with a simple starvation model

    Science.gov (United States)

    Gutcke, Thales A.; Macciò, Andrea V.; Dutton, Aaron A.; Stinson, Greg S.

    2017-01-01

    The decrease in star formation (SF) and the morphological change necessary to produce the z = 0 elliptical galaxy population are commonly ascribed to a sudden quenching event, which is able to rid the central galaxy of its cold gas reservoir in a short time. Following this event, the galaxy is able to prevent further SF and stay quiescent via a maintenance mode. We test whether such a quenching event is truly necessary using a simple model of quiescence. In this model, hot gas (all gas above a temperature threshold) in a ˜1012 M⊙ halo mass galaxy at redshift z ˜ 3 is prevented from cooling. The cool gas continues to form stars at a decreasing rate and the galaxy stellar mass, morphology, velocity dispersion and position on the color magnitude diagram (CMD) proceed to evolve. By z = 0, the halo mass has grown to 1013 M⊙ and the galaxy has attained characteristics typical of an observed z = 0 elliptical galaxy. Our model is run in the framework of a cosmological, smooth particle hydrodynamic code which includes SF, early stellar feedback, supernova feedback, metal cooling and metal diffusion. Additionally, we post-process our simulations with a radiative transfer code to create a mock CMD. In contrast to previous assumptions that a pure "fade away" model evolves too slowly to account for the sparsity of galaxies in the "green valley", we demonstrate crossing times of ≲ 1 Gyr. We conclude that no sudden quenching event is necessary to produce such rapid colour transitions.

  16. Pulse and quench induced dynamical phase transition in a chiral multiferroic spin chain

    Science.gov (United States)

    Azimi, M.; Sekania, M.; Mishra, S. K.; Chotorlishvili, L.; Toklikishvili, Z.; Berakdar, J.

    2016-08-01

    Quantum dynamics of magnetic order in a chiral multiferroic chain is studied. We consider two different scenarios: ultrashort terahertz excitations or a sudden electric field quench. Performing analytical and numerical exact diagonalization calculations, we trace the pulse induced spin dynamics and extract quantities that are relevant to quantum information processing. In particular, we analyze the dynamics of the system chirality, the von Neumann entropy, and the pairwise and many-body entanglement. If the characteristic frequencies of the generated states are noncommensurate, then a partial loss of pair concurrence occurs. Increasing the system size, this effect becomes even more pronounced. Many-particle entanglement and chirality are robust and persist in the incommensurate phase. To analyze the dynamical quantum transitions for the quenched and pulsed dynamics we combined the Weierstrass factorization technique for entire functions and the Lanczos exact diagonalization method. For a small system we obtained analytical results including the rate function of the Loschmidt echo. Exact numerical calculations for a system up to 40 spins confirm phase transition. Quench-induced dynamical transitions have been extensively studied recently. Here we show that related dynamical transitions can be achieved and controlled by appropriate electric field pulses.

  17. Effects of Local Environment and Stellar Mass on Galaxy Quenching out to z~3

    CERN Document Server

    Darvish, Behnam; Sobral, David; Rettura, Alessandro; Scoville, Nick; Faisst, Andreas; Capak, Peter

    2016-01-01

    We study the effects of local environment and stellar mass on galaxy properties using a mass complete sample of quiescent and star-forming systems in the COSMOS field at $z\\lesssim$ 3. We show that at $z\\lesssim$ 1, the median star-formation rate (SFR) and specific SFR (sSFR) of all galaxies depend on environment, but they become independent of environment at $z\\gtrsim$ 1. However, we find that only for \\textit{star-forming} galaxies, the median SFR and sSFR are similar in different environments, regardless of redshift and stellar mass. We find that the quiescent fraction depends on environment at $z\\lesssim$ 1, and on stellar mass out to $z\\sim$ 3. We show that at $z\\lesssim$ 1, galaxies become quiescent faster in denser environments and that the overall environmental quenching efficiency increases with cosmic time. Environmental and mass quenching processes depend on each other. At $z\\lesssim$ 1, denser environments more efficiently quench galaxies with higher masses (log($M/M_{\\odot}$)$\\gtrsim$ 10.7), poss...

  18. Physical properties of Rh substituted CaFe2As2 tuned by annealing/quenching

    Science.gov (United States)

    Ran, Sheng; Bud'Ko, Sergey; Canfield, Paul

    2014-03-01

    Our previous work on CaFe2As2 single crystal grown out of FeAs flux has shown that a process of annealing and quenching can be used as an additional control parameter which can tune the ground state of CaFe2As2 systematically. We have also shown that CaFe2As2 is very pressure sensitive. Therefore, unlike the BaFe2As2 system, the effect of 4d transition metal substitution on CaFe2As2 is expected to be largely different from that of 3d transition metal substitution (e.g. cobalt or nickel substitution). In this talk we will present results of measurements on a Rh substituted CaFe2As2 system with different annealing/quenching temperatures. Phase diagrams with substitution level and annealing/quenching temperature as independent parameters are constructed and compared with that of other transition metal substitutions. Supported by the U.S. Department of Energy Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

  19. Mechanical Behavior Analysis of a Test Coil for MICE Coupling Solenoid during Quench

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Heng; Wang, Li; Guo, Xinglong; Wu, Hong; Green, M.A.

    2009-10-28

    The coupling magnet for the Muon Ionization Cooling Experiment has a self-inductance of 592 H and the magnet stored energy of 13 MJ at a full current of 210 A for the worst operation case of the MICE channel. The high level of stored energy in the magnet can cause high peak temperature during a quench and induce considerable impact of stresses. One test coil was built in order to validate the design method and to practice the stress and strain situation to occur in the coupling coil. In this study, the analysis on stress redistribution during a quench with sub-divided winding was performed. The stress variation may bring about failure of impregnating material such as epoxy resin, which is the curse of a new normal zone arising. Spring models for impregnating epoxy and fiber-glass cloth in the coil were used to evaluate the mechanical disturbance by impregnated materials failure. This paper presents the detailed dynamic stress and stability analysis to assess the stress distribution during the quench process and to check whether the transient loads are acceptable for the magnet.

  20. Quenching and blue shift of UV emission intensity of hydrothermally grown ZnO:Mn nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Vinod, R. [Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Junaid Bushiri, M., E-mail: junaidbushiri@gmail.com [Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Achary, Sreekumar Rajappan; Muñoz-Sanjosé, Vicente [Departamento de FisicaAplicada y Electromagnetismo, Universitat de Valencia, c/Dr. Moliner 50, Burjassot, Valencia 46100 (Spain)

    2015-01-15

    Highlights: • Single crystalline ZnO:Mn nanorods. • Reduced optical active defects. • Quenching and blue shift of UV emission. - Abstract: ZnO:Mn alloyed nanorods (Mn nominal concentration – 3–5 wt%) were synthesized by using hydrothermal process at an optimized growth temperature of 200 °C and a growth time of 3 h. The XRD, SEM and Raman, FTIR investigations reveal that ZnO:Mn (Mn – 3–5 wt%) retained hexagonal wurtzite crystal structure with nanorod morphology. The HRTEM and SAED analysis confirm the single crystalline nature of hydrothermally grown ZnO and ZnO:Mn (5 wt%) nanorods. The ZnO:Mn nanorods (Mn – 0–5 wt%) displayed optical band gap in the range 3.23–3.28 eV. The blue shift of UV emission peak (PL) from 393 (ZnO) to 386 nm and quenching of photoluminescence emission in ZnO:Mn is due to the Mn incorporation in ZnO lattice. Relative increase in intensity of Raman band at 660 cm{sup −1} with nominal doping of Mn 3–5 wt% in ZnO indicate that defects are introduced in ZnO:Mn system as a result of doping that leads to the quenching of photoluminescence emission at 393 nm.

  1. Environmental Quenching and Galactic Conformity in the Galaxy Cross-Correlation Signal

    CERN Document Server

    Hatfield, P W

    2016-01-01

    It has long been known that environment has a large effect on star formation in galaxies. There are several known plausible mechanisms to remove the cool gas needed for star formation, such as strangulation, harassment and ram-pressure stripping. It is unclear which process is dominant, and over what range of stellar mass. In this paper, we find evidence for suppression of the cross-correlation function between massive galaxies and less massive star-forming galaxies, giving a measure of how less likely a galaxy is to be star-forming in the vicinity of a more massive galaxy. We develop a formalism for modelling environmental quenching mechanisms within the Halo Occupation Distribution formalism. We find that at $z \\sim 2$ environment is not a significant factor in determining quenching of star-forming galaxies, and that galaxies are quenched with similar probabilities in group environments as they are globally. However, by $z \\sim 0.5$ galaxies are much less likely to be star forming when in a group environmen...

  2. Evolution of the Oxidation State of the Earth's Mantle: Challenges of High Pressure Quenching

    Science.gov (United States)

    Danielson, L. R.; Righter, K.; Keller, L.; Christoffersen, R.; Rahman, Z.

    2015-01-01

    The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion, transitioned from reduced to oxidized, or from oxidized to reduced. We investigate the stability of Fe3+ at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. Experiments of more mafic compositions and at higher pressures commonly form a polyphase quench intergrowth composed primarily of pyroxenes, with interstitial glass which hosts nearly all of the more volatile minor elements. In our previous experiments on shergottite compositions, variable fO2, T, and P is less than 4 GPa, Fe3+/TotFe decreased slightly with increasing P, similar to terrestrial basalt. For oxidizing experiments less than 7GPa, Fe3+/TotFe decreased as well, but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3+. Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Experiments with Knippa basalt as the starting composition were conducted at 1-8 GPa and 1800 C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products from 7-8 GPa quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal Fe3+/2+. A number of different approaches have been employed to produce glassy samples that can be measured by EELS and XANES. A more intermediate andesite was used in one experiment, and decompression during quenching was attempted after, but both resulted in a finer grained polyphase texture. Experiments are currently underway to test different capsule materials may affect quench texture. A preliminary experiment using liquid nitrogen to greatly enhance the rate of cooling of the assembly has also been attempted and this technique will be

  3. Spectroscopic evidence of xanthine compounds fluorescence quenching effect on water-soluble porphyrins

    Science.gov (United States)

    Makarska-Bialokoz, Magdalena

    2015-02-01

    The formation of π-stacked complexes between water-soluble porphyrins: 4,4‧,4″,4″‧-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H2TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (H2TPPS4), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H2TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphine tetra-p-tosylate (H2TMePyP), the Cu(II) complexes of H2TTMePP and H2TMePyP, as well as chlorophyll a with xanthine, theophylline (1,3-dimethylxanthine) and theobromine (3,7-dimethylxanthine) has been studied analysing their absorption and steady-state fluorescence spectra in aqueous (or acetone in case of chlorophyll a) solution. During titration by the compounds from xanthine group the bathochromic effect in the porphyrin absorption spectra as well as the hypochromicity of the porphyrin Soret maximum can be noticed. The fluorescence quenching effect observed during interactions in the systems examined suggests the process of static quenching. The association and fluorescence quenching constants are of the order of magnitude of 103 - 102 mol-1. The results obtained show that xanthine and its derivatives can quench the fluorescence of the porphyrins according to the number of methyl groups in the molecule of quencher.

  4. Quenching and enhancement of single-molecule fluorescence under metallic and dielectric tips

    Science.gov (United States)

    Azoulay, J.; Débarre, A.; Richard, A.; Tchénio, P.

    2000-08-01

    We report on fluorescence experiments by apertureless near-field optical microscopy. We develop a simple model that demonstrates the importance of non-radiative transfer and that takes into account the dependence of non-radiative transfer on tip geometry. This process is in competition with field enhancement and it is a key process to understand the observed fluorescence enhancement factors. The analysis of the different factors involved in the global fluorescence enhancement or quenching leads to new strategies to reach resolution down to a few nanometers by apertureless fluorescence microscopy.

  5. Alleviating alpha quenching by solar wind and meridional flow

    CERN Document Server

    Mitra, Dhrubaditya; Tavakol, Reza; Brandenburg, Axel

    2010-01-01

    We study the ability of magnetic helicity expulsion to alleviate catastrophic $\\alpha$-quenching in mean field dynamos in two--dimensional spherical wedge domains. Motivated by the physical state of the outer regions of the Sun, we consider $\\alpha^2\\Omega$ mean field models with a dynamical $\\alpha$ quenching. We include two mechanisms which have the potential to facilitate helicity expulsion, namely advection by a mean flow (``solar wind'') and meridional circulation. We find that a wind alone can prevent catastrophic quenching, with the field saturating at finite amplitude. In certain parameter ranges, the presence of a large-scale meridional circulation can reinforce this alleviation. However, the saturated field strengths are typically below the equipartition field strength. We discuss possible mechanisms that might increase the saturated field.

  6. Alleviating α quenching by solar wind and meridional flows

    Science.gov (United States)

    Mitra, D.; Moss, D.; Tavakol, R.; Brandenburg, A.

    2011-02-01

    Aims: We study the ability of magnetic helicity expulsion to alleviate catastrophic α-quenching in mean field dynamos in two-dimensional spherical wedge domains. Methods: Motivated by the physical state of the outer regions of the Sun, we consider α^2Ω mean field models with a dynamical α quenching. We include two mechanisms which have the potential to facilitate helicity expulsion, namely advection by a mean flow ("solar wind") and meridional circulation. Results: We find that a wind alone can prevent catastrophic quenching, with the field saturating at finite amplitude. In certain parameter ranges, the presence of a large-scale meridional circulation can reinforce this alleviation. However, the saturated field strengths are typically below the equipartition field strength. We discuss possible mechanisms that might increase the saturated field.

  7. Testing chiral effective theory with quenched lattice QCD

    CERN Document Server

    Giusti, Leonardo; Necco, S; Peña, C; Wennekers, J; Wittig, H

    2008-01-01

    We investigate two-point correlation functions of left-handed currents computed in quenched lattice QCD with the Neuberger-Dirac operator. We consider two lattice spacings a~0.09,0.12 fm and two different lattice extents L~ 1.5, 2.0 fm; quark masses span both the p- and the epsilon-regimes. We compare the results with the predictions of quenched chiral perturbation theory, with the purpose of testing to what extent the effective theory reproduces quenched QCD at low energy. In the p-regime we test volume and quark mass dependence of the pseudoscalar decay constant and mass; in the epsilon-regime, we investigate volume and topology dependence of the correlators. While the leading order behaviour predicted by the effective theory is very well reproduced by the lattice data in the range of parameters that we explored, our numerical data are not precise enough to test next-to-leading order effects.

  8. Quench tank in-leakage diagnosis at St. Lucie

    Energy Technology Data Exchange (ETDEWEB)

    Price, J.E.; Au-Yang, M.K.; Beckner, D.A.; Vickery, A.N.

    1996-12-01

    In February 1995, leakage into the quench tank of the St. Lucie Nuclear Station Unit 1 was becoming an operational concern. This internal leak resulted in measurable increases in both the temperature and level of the quench tank water, and was so severe that, if the trend continued, plant shut down would be necessary. Preliminary diagnosis based on in-plant instrumentation indicated that any one of 11 valves might be leaking into the quench tank. This paper describes the joint effort by two teams of engineers--one from Florida Power & Light, the other from Framatome Technologies--to identify the sources of the leak, using the latest technology developed for valve diagnosis.

  9. Evidence for hard chiral logarithms in quenched lattice QCD

    CERN Document Server

    Kim, S; Kim, Seyong; Sinclair, D K

    1995-01-01

    We present the first direct evidence that quenched QCD differs from full QCD in the chiral (m_q \\rightarrow 0) limit, as predicted by chiral perturbation theory, from our quenched lattice QCD simulations at \\beta = 6/g^2 = 6.0. We measured the spectrum of light hadrons on 16^3 \\times 64, 24^3 \\times 64 and 32^3 \\times 64, using staggered quarks of masses m_q=0.01, m_q=0.005 and m_q=0.0025. The pion masses showed clear evidence for logarithmic violations of the PCAC relation m_{\\pi}^2 \\propto m_q, as predicted by quenched chiral perturbation theory. The dependence on spatial lattice volume precludes this being a finite size effect. No evidence was seen for such chiral logarithms in the behaviour of the chiral condensate \\langle\\bar{\\psi}\\psi\\rangle.

  10. Testing chiral effective theory with quenched lattice QCD

    Science.gov (United States)

    Giusti, L.; Hernández, P.; Necco, S.; Pena, C.; Wennekers, J.; Wittig, H.

    2008-05-01

    We investigate two-point correlation functions of left-handed currents computed in quenched lattice QCD with the Neuberger-Dirac operator. We consider two lattice spacings a simeq 0.09,0.12 fm and two different lattice extents L simeq 1.5,2.0 fm; quark masses span both the p- and the epsilon-regimes. We compare the results with the predictions of quenched chiral perturbation theory, with the purpose of testing to what extent the effective theory reproduces quenched QCD at low energy. In the p-regime we test volume and quark mass dependence of the pseudoscalar decay constant and mass; in the epsilon-regime, we investigate volume and topology dependence of the correlators. While the leading order behaviour predicted by the effective theory is very well reproduced by the lattice data in the range of parameters that we explored, our numerical data are not precise enough to test next-to-leading order effects.

  11. Universal corrections to entanglement entropy of local quantum quenches

    CERN Document Server

    David, Justin R; Kumar, S Prem

    2016-01-01

    We study the time evolution of single interval Renyi and entanglement entropies following local quantum quenches in two dimensional conformal field theories at finite temperature for which the locally excited states have a finite temporal width, \\epsilon. We show that, for local quenches produced by the action of a conformal primary field, the time dependence of Renyi and entanglement entropies at order \\epsilon^2 is universal. It is determined by the expectation value of the stress tensor in the replica geometry and proportional to the conformal dimension of the primary field generating the local excitation. We also show that in CFTs with a gravity dual, the \\epsilon^2 correction to the holographic entanglement entropy following a local quench precisely agrees with the CFT prediction. We then consider CFTs admitting a higher spin symmetry and turn on a higher spin chemical potential \\mu. We calculate the time dependence of the order \\epsilon^2 correction to the entanglement entropy for small \\mu, and show th...

  12. Increasing the Useful Life of Quench Reliefs with Inconel Bellows

    Energy Technology Data Exchange (ETDEWEB)

    Soyars, W. M. [Fermilab

    1999-01-01

    Reliable quench relief valves are an important part of superconducting magnet systems. Fermilab developed bellows-actuated cryogenic quench reliefs which have been in use since the early l 980's. The original design uses a stainless steel bellows. A high frequency, low amplitude vibration during relieving events has resulted in fatigue failures in the original design. To take advantage of the improved resistance to fatigue of Inconel, a nickel-chromium alloy, reliefs using Inconel 625 bellows were made. Design, development, and testing of the new version reliefs will be discussed. Tests show that relief valve lifetimes using Inconel bellows are more than five times greater than when using the original stainless steel bellows. Inconel bellows show great promise in increasing the lifetime of quench relief valves, and thus the reliability of accelerator cryogenic systems.

  13. Quench Detection and Protection of the MQT Type Magnet

    CERN Document Server

    Teng, M

    1998-01-01

    The LHC design as from version 5 is equipped with tuning, trim and skew quadrupoles with similar cross-section designs (MQT). To qualify the quench detection and magnet protection needs, several compu tational methods have been applied. They range from global calculation of a uniform adiabatic temperature rise to more refined simulations, including the Quaber simulation package which is also applie d for quench calculations on the main magnets. A very important parameter is the quench propagation velocity, on which the Quaber simulations rely. An attempt was made to simulate the physics of the p ropagation itself, taking into account the temperature dependence of the wire parameters with the Quenchprop algorithm described in this report. The calculated results were compared with those from ex periments on a single wire. Further results of measurements on prototype magnets will allow fine-tuning of the program parameters.

  14. Residual stress in quenched 7075 aluminum alloy thick plates

    Institute of Scientific and Technical Information of China (English)

    林高用; 张辉; 朱伟; 彭大暑; 梁轩; 周鸿章

    2003-01-01

    The influence of quenching water temperature, pre-stretching amount and aging temperature and times on residual stress in 7075 aluminum thick plate was studied by the measurement of residual stress using drilling hole method. The results indicate that residual stress decreases by 30% with increasing quenching water temperature from 40 ℃ to 80 ℃, 20% with increasing aging temperature from 100 ℃ to 180 ℃,and 20% with increasing aging times from 5 h to 25 h. Also, residual stress decreases to zero with increasing pre-stretching amount to approximately 2%. Hence, residual stress in 7075 aluminum thick plate is reduced by the control of quenching water temperature at 80 ℃ and with pre-stretching amount of about 2%. An optimal aging temperature and time should be systemically investigated to obtain combination of high mechanical performances and lower residual stress for manufacturing of 7075 aluminum alloy thick plates.

  15. Numerical analysis of quench in coated conductors with defects

    Science.gov (United States)

    Liu, Wenbin; Yong, Huadong; Zhou, Youhe

    2016-09-01

    When the superconductor is subjected to local thermal perturbations, a large amount of joule heat may be generated in the conductor, which may lead to a quench. In a quench event, a normal zone irreversibly spreads throughout the conductor leading to failure of the superconducting device. In this paper, we will discuss the one-dimensional quench behavior in the coated conductors with internal defects or interface defects. Based on the numerical procedure given in the previous works, the normal zone propagation is studied by using the finite difference method. The numerical results are presented to discuss the normal zone propagation. We consider the effect of internal defect on the nonuniform temperature propagation. For the conductor with interface defects, it can be found that the normal zone propagation velocity is increased by defects.

  16. Generalized thermalization for integrable system under quantum quench

    CERN Document Server

    Muralidharan, Sushruth; Shankaranarayanan, S

    2016-01-01

    We investigate equilibration and generalized thermalization of quantum Harmonic chain --- an integrable system which in the thermodynamic limit mimics a free scalar field --- under global quantum quench. The quench action we consider is connecting two disjoint harmonic chains of different sizes and the system jumps between two integrable settings. We verify the validity of the Generalized Gibbs Ensemble description for this system and also identify equilibration between the subsystems as in classical systems. Using Bogoliubov transformations, we show that the eigenstates of the system prior to the quench evolve towards the Gibbs Generalized Ensemble description. Further, through the phase space properties of a Generalized Gibbs Ensemble and the strength of stimulated emission, we identify the necessary criterion on the initial states for the thermalization at late times, which is satisfied by the system in the thermodynamic limit.

  17. Numerical analysis of quench in coated conductors with defects

    Directory of Open Access Journals (Sweden)

    Wenbin Liu

    2016-09-01

    Full Text Available When the superconductor is subjected to local thermal perturbations, a large amount of joule heat may be generated in the conductor, which may lead to a quench. In a quench event, a normal zone irreversibly spreads throughout the conductor leading to failure of the superconducting device. In this paper, we will discuss the one-dimensional quench behavior in the coated conductors with internal defects or interface defects. Based on the numerical procedure given in the previous works, the normal zone propagation is studied by using the finite difference method. The numerical results are presented to discuss the normal zone propagation. We consider the effect of internal defect on the nonuniform temperature propagation. For the conductor with interface defects, it can be found that the normal zone propagation velocity is increased by defects.

  18. Characterization of plasma current quench during disruption in EAST tokamak

    Institute of Scientific and Technical Information of China (English)

    陈大龙; 沈飙; 杨飞; 钱金平; 肖炳甲

    2015-01-01

    Preliminary analysis of plasma current quench is presented in this paper based on the disruption database. It demon-strates that 26.8%discharges have disrupted in the last 2012 campaign, in addition, plasma disruptive rate grows with the increase of plasma current. Best-fit linear and instantaneous plasma current quench rate is extracted from the recent EAST disruptions, showing that 80%–30%interval of the maximum plasma current is well fit for EAST device. The lowest area-normalized current quench time is 3.33 ms/m2 with the estimated plasma electron temperature being 7.3 eV∼9.5 eV. In the disruption case the maximum eddy current goes up to 400 kA, and a fraction of currents are respectively driven on upper and lower outer plate with nearly 100 MPa–200 MPa stress in the leg.

  19. Hamiltonian truncation approach to quenches in the Ising field theory

    CERN Document Server

    Rakovszky, Tibor; Collura, Mario; Kormos, Márton; Takács, Gábor

    2016-01-01

    In contrast to lattice systems where powerful numerical techniques such as matrix product state based methods are available to study the non-equilibrium dynamics, the non-equilibrium behaviour of continuum systems is much harder to simulate. We demonstrate here that Hamiltonian truncation methods can be efficiently applied to this problem, by studying the quantum quench dynamics of the 1+1 dimensional Ising field theory using a truncated free fermionic space approach. After benchmarking the method with integrable quenches corresponding to changing the mass in a free Majorana fermion field theory, we study the effect of an integrability breaking perturbation by the longitudinal magnetic field. In both the ferromagnetic and paramagnetic phases of the model we find persistent oscillations with frequencies set by the low-lying particle excitations even for moderate size quenches. In the ferromagnetic phase these particles are the various non-perturbative confined bound states of the domain wall excitations, while...

  20. Numerical calculation of transient field effects in quenching superconducting magnets

    CERN Document Server

    Schwerg, Nikolai; Russenschuck, Stephan

    2009-01-01

    The maximum obtainable magnetic induction of accelerator magnets, relying on normal conducting cables and iron poles, is limited to around 2 T because of ohmic losses and iron saturation. Using superconducting cables, and employing permeable materials merely to reduce the fringe field, this limit can be exceeded and fields of more than 10 T can be obtained. A quench denotes the sudden transition from the superconducting to the normal conducting state. The drastic increase in electrical resistivity causes ohmic heating. The dissipated heat yields a temperature rise in the coil and causes the quench to propagate. The resulting high voltages and excessive temperatures can result in an irreversible damage of the magnet - to the extend of a cable melt-down. The quench behavior of a magnet depends on numerous factors, e.g. the magnet design, the applied magnet protection measures, the external electrical network, electrical and thermal material properties, and induced eddy current losses. The analysis and optimizat...

  1. Beam-induced quench test of LHC main quadrupole

    CERN Document Server

    Priebe, A; Dehning, B; Effinger, E; Emery, J; Holzer, E B; Kurfuerst, C; Nebot Del Busto, E; Nordt, A; Sapinski, M; Steckert, J; Verweij, A; Zamantzas, C

    2011-01-01

    Unexpected beam loss might lead to a transition of the accelerator superconducting magnet to a normal conducting state. The LHC beam loss monitoring (BLM) system is designed to abort the beam before the energy deposited in the magnet coils reach a quench-provoking level. In order to verify the threshold settings generated by simulation, a series of beam-induced quench tests at various beam energies has been performed. The beam losses are generated by means of an orbital bump peaked in one of main quadrupole magnets (MQ). The analysis includes not only BLM data but also the quench protection system (QPS) and cryogenics data. The measurements are compared to Geant4 simulations of energy deposition inside the coils and corresponding BLM signal outside the cryostat.

  2. Modeling the jet quenching in hot and dense QCD matter

    CERN Document Server

    Lokhtin, I P; Petrushanko, S V; Snigirev, A M; Arsene, I; Tywoniuk, K

    2009-01-01

    One of the important perturbative ("hard") probes of hot and dense QCD matter is the medium-induced energy loss of energetic partons, so called "jet quenching", which is predicted to be very different in cold nuclear matter and in QGP, and leads to a number of phenomena which are already seen in the RHIC data on the qualitative level. The inclusion of jet quenching and other important collective effects, such as radial and elliptic flows, in the existing Monte-Carlo models of relativistic heavy ion collisions is discussed. Some issues on the corresponding physical observables at RHIC and LHC energies obtained with HYDJET++ model are presented.

  3. Jet quenching in heavy ion collisions at LHC

    CERN Document Server

    Lokhtin, Igor P

    2003-01-01

    We discuss the potential information about highly excited QCD-matter provided by medium-induced partonic energy loss, known as ``jet quenching''. In particular, with its large acceptance hadronic and electromagnetic calorimetry, the Compact Muon Solenoid detector at LHC collider is a promising device to study these effects. We present physics simulations of observables such as the jet distribution with impact parameter, the azimuthal anisotropy of jet quenching, and the effects of b-quark energy loss on the high-mass dimuon continuum and secondary charmonium production.

  4. Study of quench propagation velocity in superconducting magnets for UNK

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, I.V.; Sheherbakov, P.A.; Snitko, V.P.; Tkachenko, N.P.; Vasiliev, L.M.; Vybornov, M.G.; Ziobin, A.V.

    1989-03-01

    Two superconducting magnet models, warm-iron and cold-iron designs are studied within the frames of work on UNK. The present note describes the method and results on measuring quench propagation velocity in the superconducting cables with a transport current in external field under the cooling conditions typical for those of the magnet winding. The results on measuring quench propagation velocities in warm-iron and cold-iron designs are presented. The results obtained for short samples and model coils are compared.

  5. Overlaps after quantum quenches in the sine-Gordon model

    Science.gov (United States)

    Horváth, D. X.; Takács, G.

    2017-08-01

    We present a numerical computation of overlaps in mass quenches in sine-Gordon quantum field theory using truncated conformal space approach (TCSA). To improve the cut-off dependence of the method, we use a novel running coupling definition which has a general applicability in free boson TCSA. The numerical results for the first breather overlaps are compared with the analytic continuation of a previously proposed analytical Ansatz for the initial state in a related sinh-Gordon quench, and good agreement is found between the numerical data and the analytical prediction in a large energy range.

  6. Sudden interaction quench in the quantum sine-Gordon model

    Energy Technology Data Exchange (ETDEWEB)

    Sabio, Javier [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain); Kehrein, Stefan, E-mail: javier.sabio@icmm.csic.e [Arnold-Sommerfeld-Center for Theoretical Physics, Center for NanoSciences and Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, 80333 Muenchen (Germany)

    2010-05-15

    We study a sudden interaction quench in the weak-coupling regime of the quantum sine-Gordon model. The real time dynamics of the bosonic mode occupation numbers is calculated using the flow equation method. While we cannot prove results for the asymptotic long-time limit, we can establish the existence of an extended regime in time where the mode occupation numbers relax to twice their equilibrium values. This factor two indicates a non-equilibrium distribution and is a universal feature of weak interaction quenches. The weak-coupling quantum sine-Gordon model therefore turns out to be on the borderline between thermalization and non-thermalization.

  7. Quench dynamics of TQPT in Wen-plaquette model

    CERN Document Server

    Zhang, Long; Deng, Youjing

    2010-01-01

    In this paper, we study quench dynamics of topological quantum phase transition (TQPT) in transverse Wen-plaquette model, which has a phase transition from $Z_{2}$ topological order to a spin-polarized state. The study is based on others' work on Ising model, for 2D Wen-plaquette model with a external field can be mapped to 1D quantum Ising model. Using the mapping, we get the expression of SOPs and calculate the number of quasiparticles after a linear quench. The result tells us when the evolution is adiabatic, half of the plaquettes will be turned into $F_{i}=-1$.

  8. Generation of runaway electrons during the thermal quench in tokamaks

    Science.gov (United States)

    Aleynikov, Pavel; Breizman, Boris N.

    2017-04-01

    This work provides a systematic description of electron kinetics during impurity dominated thermal quenches. A Fokker–Planck equation for the hot electrons and a power balance equation for the bulk plasma are solved self-consistently, with impurity radiation as the dominant energy loss mechanism. We find that runaway production is facilitated by heavy injection of impurities up to prompt conversion of the total current into a sub-MeV runaway current. We also find that runaway formation is less efficient in plasmas with high pre-quench temperatures and predict significant radial variation of the runaway seed in such plasmas.

  9. Magnetostriction of the rapidly quenched Co80Nb8B12 alloy: Dependence on quenching rate, structural relaxation, and temperature

    DEFF Research Database (Denmark)

    Madurga, V.; Barandiarán, J. M.; Vázquez, M.

    1987-01-01

    Ribbons of nominal composition Co80Nb8B12 have been prepared by the single roller quenching method using different wheel velocities ranging from 26 to 42 ms−1. X-ray diffraction patterns for ribbons prepared at low velocities show crystalline peaks but characteristic for the amorphous state...... for samples prepared at velocities above 36 ms−1. Room-temperature values of the magnetostriction constant lambdas depend on the quenching rate and changes from 4×10−7 to −1×10−6 as the wheel speed increases. Zero magnetostriction samples are obtained at about 34 ms−1. Thermal treatments change the values...... of the magnetostriction in the same way as a decrease in the quenching rate does. A dependence of the magnetostriction constant on the applied stress has been found. This dependence, fully reversible, is observed at room temperature. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  10. Biological removal of organic constituents in quench water from a slagging, fixed-bed coal-gasification pilot plant

    Energy Technology Data Exchange (ETDEWEB)

    Stamoudis, V C; Luthy, R G

    1980-02-01

    This study is part of an effort to assess the efficiency of activated-sludge treatment for removal of organic constituents from high-Btu coal-gasification pilot-plant quench waters. A sample of raw-gas quench water was obtained from the Grand Forks Energy and Technology Center's pilot plant, which employs the slagging, fixed-bed gasification process. The quench water generated in the processing of Indian Head lignite was pretreated to reduce ammonia and alkalinity, and then diluted and subjected to long-term biological treatment, followed by detailed characterization and analysis of organic constituents. The pretreated (influent) and treated (effluent) samples were extracted using a methylene chloride, pH-fractionation method to obtain acid, base, and neutral fractions, which were analyzed by capillary-column gas chromatography/mass spectrometry (GC/MS). Over 99% of the total extractable and chromatographable organic material in the influent acid fraction was composed of phenol and alkylated phenols. Biological treatment removed these compounds almost completely. Major components of the influent base fraction were alkylated pyridines, anilines, aminopyrroles, imidazoles and/or pyrazoles, diazines, and quinolines. Removal efficiency of these compounds ranged between 90 and 100%. The influent neutral fraction was composed mainly of cycloalkanes, cycloalkenes, naphthalene, indole, acetophenone, and benzonitrile. Alkylated benzenes were generally absent. Removal efficiencies of these compounds were generally very good, except for certain alkylated cycloalkanes and cycloalkenes. Results are compared with those of a similar study on HYGAS coal-gasification quench water.

  11. Quorum Sensing and Quorum Quenching in the Phycosphere of Phytoplankton: a Case of Chemical Interactions in Ecology.

    Science.gov (United States)

    Rolland, Jean Luc; Stien, Didier; Sanchez-Ferandin, Sophie; Lami, Raphaël

    2016-12-01

    The interactions between bacteria and phytoplankton regulate many important biogeochemical reactions in the marine environment, including those in the global carbon, nitrogen, and sulfur cycles. At the microscopic level, it is now well established that important consortia of bacteria colonize the phycosphere, the immediate environment of phytoplankton cells. In this microscale environment, abundant bacterial cells are organized in a structured biofilm, and exchange information through the diffusion of small molecules called semiochemicals. Among these processes, quorum sensing plays a particular role as, when a sufficient abundance of cells is reached, it allows bacteria to coordinate their gene expression and physiology at the population level. In contrast, quorum quenching mechanisms are employed by many different types of microorganisms that limit the coordination of antagonistic bacteria. This review synthesizes quorum sensing and quorum quenching mechanisms evidenced to date in the phycosphere, emphasizing the implications that these signaling systems have for the regulation of bacterial communities and their activities. The diversity of chemical compounds involved in these processes is examined. We further review the bacterial functions regulated in the phycosphere by quorum sensing, which include biofilm formation, nutrient acquisition, and emission of algaecides. We also discuss quorum quenching compounds as antagonists of quorum sensing, their function in the phycosphere, and their potential biotechnological applications. Overall, the current state of the art demonstrates that quorum sensing and quorum quenching regulate a balance between a symbiotic and a parasitic way of life between bacteria and their phytoplankton host.

  12. Quenching of coumarin emission by CdSe and CdSe/ZnS quantum dots: Implications for fluorescence reporting

    Energy Technology Data Exchange (ETDEWEB)

    Baride, Aravind [Department of Chemistry, University of South Dakota, Vermillion, SD 57069 (United States); Engebretson, Daniel [Biomedical Engineering, University of South Dakota, Vermillion, SD 57069 (United States); Berry, Mary T. [Department of Chemistry, University of South Dakota, Vermillion, SD 57069 (United States); Stanley May, P., E-mail: smay@usd.edu [Department of Chemistry, University of South Dakota, Vermillion, SD 57069 (United States)

    2013-09-15

    The photoinduced release of highly fluorescent 7-diethylamino coumarin (7DEAC) from CdSe quantum dots (QD) modified with a thiocinnamate ligand (11-mercapto undecyl-E-3-(4-(N,N-diethylamino)-2-hydroxy phenyl) propenoate, [4DEATC]) has been previously described. Coumarin fluorescence was used to ‘report’ the photochemical reaction. The current study quantifies the quenching effect of the QDs on the coumarin emission in this system. A systematic study is presented on the quenching of 7DEAC by CdSe and CdSe/ZnS quantum dots capped with 2-[2-(2-methoxyethoxy)ethoxy] ethanethiol (PEG-thiol). A new method for the functionalization of CdSe and CdSe/ZnS QDs with PEG-thiol was developed, which does not require isolation of the as-synthesized QDs. Stern–Volmer analysis was applied to quantify the effect of the PEG-CdSe and PEG-CdSe/ZnS on 7DEAC emission. The Stern–Volmer constant, K{sub SV}, was shown to be inversely proportional to temperature for quenching by PEG-CdSe, and the fluorescence lifetime of 7DEAC was shown to be independent of PEG-CdSe concentration. Room-temperature K{sub SV} values were similar for the PEG-CdSe and PEG-CdSe/ZnS quenchers. The large magnitude of K{sub SV}, the temperature dependence of K{sub SV}, the lifetime data, and the similarity of K{sub SV} values for the core and core–shell QD quenchers are all consistent with a static quenching mechanism. Assuming a static quenching mechanism, the temperature dependence of the coumarin-QD binding constant, K{sub b}, was used to estimate the ΔH and ΔS for the binding process. -- Highlights: • Quenching of a coumarin derivative by CdSe and CdSe/ZnS quantum dots is demonstrated • Stern–Volmer analysis is performed as a function of temperature • Fluorescence lifetime analysis was used to support Stern–Volmer analysis • Data overwhelmingly support quenching via a Static Mechanism • Quenching of coumarin by quantum dots is significant and must be considered in any release and report

  13. Quenching of Cross Sections in Nucleon Transfer Reactions

    CERN Document Server

    Kay, B P; Freeman, S J

    2013-01-01

    Cross sections for proton knockout observed in (e,e'p) reactions are apparently quenched by a factor of ~0.5, an effect attributed to short-range correlations between nucleons. Here we demonstrate that such quenching is not restricted to proton knockout, but a more general phenomenon associated with any nucleon transfer. Measurements of absolute cross sections on a number of targets between 16O and 208Pb were analyzed in a consistent way, with the cross sections reduced to spectroscopic factors through the distorted-wave Born approximation with global optical potentials. Across the 124 cases analyzed here, induced by various proton- and neutron-transfer reactions and with angular momentum transfer l=0-7, the results are consistent with a quenching factor of 0.55. This is an apparently uniform quenching of single-particle motion in the nuclear medium. The effect is seen not only in (d,p) reactions but also in reactions with A=3 and 4 projectiles, when realistic wave functions are used for the projectiles.

  14. Leakage-free rapid quenching technique for yeast metabolomics

    NARCIS (Netherlands)

    Canelas, A.B.; Ras, C.; Ten Pierick, A.; Van Dam, J.C.; Heijnen, J.J.; Van Gulik, W.M.

    2008-01-01

    Accurate determination of intracellular metabolite levels requires reliable, reproducible techniques for sampling and sample treatment. Quenching in 60% (v/v) methanol at −40°C is currently the standard method for sub-second arrest of metabolic activity in microbial metabolomics but there have been

  15. A Model for the Color Glass Condensate Versus Jet Quenching

    CERN Document Server

    Contogouris, Andreas P; Papachristou, P K

    2002-01-01

    A model for the Color Glass Condensate as opposed to jet quenching is proposed for the explanation of the presently available RHIC data. Good fits to these data are presented. A clear way to distinguish between the two possible explanations is also given.

  16. Siloxanes with Pendent Naphtalene Diimides: Synthesis and Fluorescence Quenching

    NARCIS (Netherlands)

    Ganesan, P.; Lagen, van B.; Marcelis, A.T.M.; Sudhölter, E.J.R.; Zuilhof, H.

    2007-01-01

    Cyclic siloxanes with pendent naphthalene diimide groups were synthesized via hydrosilylation to form amorphous electron-accepting compounds. Photophysical measurements and >99.9% fluorescence quenching of well-known p-type polymers by the siloxanes demonstrate that these siloxanes form a new cla

  17. MD290: Q4 IP6 Quench Level

    CERN Document Server

    Bednarek, Mateusz Jakub; Lechner, Anton; CERN. Geneva. ATS Department

    2016-01-01

    The detailed program proposed for the LHC Machine Development concerning a quench induced by fast losses on the MQY.4L6 quadrupole is presented. The merit of the MD, the necessary modifications of the machine protection systems are presented together with a preliminary analysis of the MD results.

  18. Hamiltonian truncation approach to quenches in the Ising field theory

    Directory of Open Access Journals (Sweden)

    T. Rakovszky

    2016-10-01

    Full Text Available In contrast to lattice systems where powerful numerical techniques such as matrix product state based methods are available to study the non-equilibrium dynamics, the non-equilibrium behaviour of continuum systems is much harder to simulate. We demonstrate here that Hamiltonian truncation methods can be efficiently applied to this problem, by studying the quantum quench dynamics of the 1+1 dimensional Ising field theory using a truncated free fermionic space approach. After benchmarking the method with integrable quenches corresponding to changing the mass in a free Majorana fermion field theory, we study the effect of an integrability breaking perturbation by the longitudinal magnetic field. In both the ferromagnetic and paramagnetic phases of the model we find persistent oscillations with frequencies set by the low-lying particle excitations not only for small, but even for moderate size quenches. In the ferromagnetic phase these particles are the various non-perturbative confined bound states of the domain wall excitations, while in the paramagnetic phase the single magnon excitation governs the dynamics, allowing us to capture the time evolution of the magnetisation using a combination of known results from perturbation theory and form factor based methods. We point out that the dominance of low lying excitations allows for the numerical or experimental determination of the mass spectra through the study of the quench dynamics.

  19. Hamiltonian truncation approach to quenches in the Ising field theory

    Science.gov (United States)

    Rakovszky, T.; Mestyán, M.; Collura, M.; Kormos, M.; Takács, G.

    2016-10-01

    In contrast to lattice systems where powerful numerical techniques such as matrix product state based methods are available to study the non-equilibrium dynamics, the non-equilibrium behaviour of continuum systems is much harder to simulate. We demonstrate here that Hamiltonian truncation methods can be efficiently applied to this problem, by studying the quantum quench dynamics of the 1 + 1 dimensional Ising field theory using a truncated free fermionic space approach. After benchmarking the method with integrable quenches corresponding to changing the mass in a free Majorana fermion field theory, we study the effect of an integrability breaking perturbation by the longitudinal magnetic field. In both the ferromagnetic and paramagnetic phases of the model we find persistent oscillations with frequencies set by the low-lying particle excitations not only for small, but even for moderate size quenches. In the ferromagnetic phase these particles are the various non-perturbative confined bound states of the domain wall excitations, while in the paramagnetic phase the single magnon excitation governs the dynamics, allowing us to capture the time evolution of the magnetisation using a combination of known results from perturbation theory and form factor based methods. We point out that the dominance of low lying excitations allows for the numerical or experimental determination of the mass spectra through the study of the quench dynamics.

  20. The quenching of the star formation activity in cluster galaxies

    CERN Document Server

    Boselli, A; Fossati, M; Buat, V; Boissier, S; Boquien, M; Burgarella, D; Ciesla, L; Gavazzi, G; Serra, P

    2016-01-01

    We study the star formation quenching mechanism in cluster galaxies by fitting the SED of the Herschel Reference Survey, a complete volume-limited K-band-selected sample of nearby galaxies including objects in different density regions, from the core of the Virgo cluster to the general field. The SED are fitted using the CIGALE SED modelling code. The truncated activity of cluster galaxies is parametrised using a specific SFH with 2 free parameters, the quenching age QA and the quenching factor QF. These 2 parameters are crucial for the identification of the quenching mechanism which acts on long timescales if starvation while rapid and efficient if ram pressure. To be sensitive to an abrupt and recent variation of the star formation activity, we combine in a new way 20 UV to FIR photometric bands with 3 age-sensitive Balmer line absorption indices extracted from available medium-resolution integrated spectroscopy and with Halpha narrow band imaging data. The use of a truncated SFH significantly increases the...

  1. Testing beam-induced quench levels of LHC superconducting magnets

    CERN Document Server

    Auchmann, B; Bednarek, M; Bellodi, G; Bracco, C; Bruce, R; Cerutti, F; Chetvertkova, V; Dehning, B; Granieri, P P; Hofle, W; Holzer, E B; Lechner, A; Del Busto, E Nebot; Priebe, A; Redaelli, S; Salvachua, B; Sapinski, M; Schmidt, R; Shetty, N; Skordis, E; Solfaroli, M; Steckert, J; Valuch, D; Verweij, A; Wenninger, J; Wollmann, D; Zerlauth, M

    2015-01-01

    In the years 2009-2013 the Large Hadron Collider (LHC) has been operated with the top beam energies of 3.5 TeV and 4 TeV per proton (from 2012) instead of the nominal 7 TeV. The currents in the superconducting magnets were reduced accordingly. To date only seventeen beam-induced quenches have occurred; eight of them during specially designed quench tests, the others during injection. There has not been a single beam- induced quench during normal collider operation with stored beam. The conditions, however, are expected to become much more challenging after the long LHC shutdown. The magnets will be operating at near nominal currents, and in the presence of high energy and high intensity beams with a stored energy of up to 362 MJ per beam. In this paper we summarize our efforts to understand the quench levels of LHC superconducting magnets. We describe beam-loss events and dedicated experiments with beam, as well as the simulation methods used to reproduce the observable signals. The simulated energy depositio...

  2. Characterization of thermal and current quench of JET plasmas

    Science.gov (United States)

    Riccardo, V.; Barabaschi, P.; Loarte, A.; Sugihara, M.

    2004-11-01

    JET provides crucial scaling points and unique physics access for the extrapolation of disruptions to ITER. Disruption and ELM heat loads influence the selection of materials for plasma facing components (PFCs). Most JET thermal quenches occur when the plasma thermal energy is less than half that at full performance, suggesting a more optimistic life expectancy for ITER PFCs. The exceptions are ITB collapses and pure VDEs, which are also more likely to lead to the shortest thermal quenches. For the fast current quench disruptions, the EM load due to the induced eddy currents represent the most severe electromechanical design condition for in-vessel components. The minimum linear decay time normalised to the plasma cross section extrapolates to a 40 ms disruption for ITER, based on data from JET and most other tokamaks. Some very fast JET events are better fit by an exponential, with the minimum characteristic current decay time scaling to 35 ms for ITER. Contrary to expectations, the quench rate of high and low thermal energy disruptions does not vary substantially.

  3. Lessons learnt from FARO/TERMOS corium melt quenching experiments

    Energy Technology Data Exchange (ETDEWEB)

    Magallon, D.; Huhtiniemi, I.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    The influence of melt quantity, melt composition, water depth and initial pressure on quenching is assessed on the basis of seven tests performed in various conditions in the TERMOS vessel of the FARO facility at JRC-Ispra. Tests involved UO{sub 2}-based melt quantities in the range 18-176 kg at a temperature of approximately 3000 K poured into saturated water. The results suggest that erosion of the melt jet column is an efficient contributor to the amount of break-up, and thus quenching, for large pours of corium melt. The presence of Zr metal in the melt induced a much more efficient quenching than in a similar test with no Zr metal, attributed to the oxidation of the Zr. Significant amounts of H{sub 2} were produced also in tests with pure oxidic melts (e.g. about 300 g for 157 kg melt). In the tests at 5.0 and 2.0 MPa good mixing with significant melt break-up and quenching was obtained during the penetration in the water. At 0.5 MPa, good penetration of the melt into the water could still be achieved, but a jump in the vessel pressurisation occurred when the melt contacted the bottom and part (5 kg) of the debris was re-ejected from the water. (author)

  4. Quenching effects for piezoelectric properties on lead-free (Bi1/2Na1/2)TiO3 ceramics

    Science.gov (United States)

    Muramatsu, Hiroki; Nagata, Hajime; Takenaka, Tadashi

    2016-10-01

    Lead-free ferroelectric and piezoelectric ceramics, (Bi0.5Na0.5)TiO3 (BNT), were fabricated by a quenching procedure after sintering, and then their electrical properties were investigated with the aim to increase their depolarization temperature T d. From the measurement of the temperature dependence of dielectric properties, T d increased with increasing quench temperature. The T d of a BNT sample quenched from 1100 °C was 223 °C, which was almost 50 °C higher than that prepared by the ordinary cooling process. From the measurement of P-E hysteresis loops, both the remanent polarization P r and the coercive field E c of BNT samples prepared by ordinary firing were almost the same as those quenched from 1100 °C. Additionally, from the measurements by a resonance-antiresonance method, the electromechanical coupling factor k 33 of ordinarily fired BNT was 0.45, and that of the quenched BNT was 0.46. From these results, it is clarified that the quenching procedure is an effective way to increase the T d of BNT ceramics without deteriorating ferroelectric and piezoelectric properties.

  5. Non-linear quenching of current fluctuations in a self-exciting homopolar dynamo, proved by feedback system theory

    OpenAIRE

    A. M. de Paor

    1998-01-01

    International audience; Hide (Nonlinear Processes in Geophysics, 1998) has produced a new mathematical model of a self-exciting homopolar dynamo driving a series- wound motor, as a continuing contribution to the theory of the geomagnetic field. By a process of exact perturbation analysis, followed by combination and partial solution of differential equations, the complete nonlinear quenching of current fluctuations reported by Hide in the case that a parameter ? has the value 1 is proved via ...

  6. Non-linear quenching of current fluctuations in a self-exciting homopolar dynamo, proved by feedback system theory

    Science.gov (United States)

    de Paor, A. M.

    Hide (Nonlinear Processes in Geophysics, 1998) has produced a new mathematical model of a self-exciting homopolar dynamo driving a series- wound motor, as a continuing contribution to the theory of the geomagnetic field. By a process of exact perturbation analysis, followed by combination and partial solution of differential equations, the complete nonlinear quenching of current fluctuations reported by Hide in the case that a parameter ɛ has the value 1 is proved via the Popov theorem from feedback system stability theory.

  7. Nanostructured Multilayer Composite Coatings on Ceramic Cutting Tools for Finishing Treatment of High-Hardness Quenched Steels

    Science.gov (United States)

    Vereshchaka, A. A.; Batako, A. D.; Sotova, E. S.; Vereshchaka, A. S.

    2016-01-01

    The functional role of nanostructured multilayer composite coatings (NMCC) deposited on the operating surfaces of replaceable faceted cutting inserts (CI) from cutting ceramics based on aluminum oxides with additives of titanium carbides is studied. It is shown that the developed NMCC not only raise substantially the endurance of the ceramic tools under high-speed dry treatment of quenched steels but also improve the quality and accuracy of processing of the parts and the ecological parameters of the cutting process.

  8. Ageing first passage time density in continuous time random walks and quenched energy landscapes

    Science.gov (United States)

    Krüsemann, Henning; Godec, Aljaž; Metzler, Ralf

    2015-07-01

    We study the first passage dynamics of an ageing stochastic process in the continuous time random walk (CTRW) framework. In such CTRW processes the test particle performs a random walk, in which successive steps are separated by random waiting times distributed in terms of the waiting time probability density function \\psi (t)≃ {t}-1-α (0≤slant α ≤slant 2). An ageing stochastic process is defined by the explicit dependence of its dynamic quantities on the ageing time ta, the time elapsed between its preparation and the start of the observation. Subdiffusive ageing CTRWs with 0\\lt α \\lt 1 describe systems such as charge carriers in amorphous semiconducters, tracer dispersion in geological and biological systems, or the dynamics of blinking quantum dots. We derive the exact forms of the first passage time density for an ageing subdiffusive CTRW in the semi-infinite, confined, and biased case, finding different scaling regimes for weakly, intermediately, and strongly aged systems: these regimes, with different scaling laws, are also found when the scaling exponent is in the range 1\\lt α \\lt 2, for sufficiently long ta. We compare our results with the ageing motion of a test particle in a quenched energy landscape. We test our theoretical results in the quenched landscape against simulations: only when the bias is strong enough, the correlations from returning to previously visited sites become insignificant and the results approach the ageing CTRW results. With small bias or without bias, the ageing effects disappear and a change in the exponent compared to the case of a completely annealed landscape can be found, reflecting the build-up of correlations in the quenched landscape.

  9. Work Hardening Behavior and Stability of Retained Austenite for Quenched and Partitioned Steels

    Institute of Scientific and Technical Information of China (English)

    Cun-yu WANG; Ying CHANG; Jie YANG; Wen-quan CAO; Han DONG; Yi-de WANG

    2016-01-01

    Both microstructure and mechanical properties of low alloy steels treated by quenching and partitioning (Q&P)process were examined.The mixed microstructure of martensite and large-fractioned retained austenite (about 27�3%)was characterized and analyzed,excellent combinations of total elongation of 1 9% and tensile strength of 1 835 MPa were obtained,and three-stage work hardening behavior was demonstrated during tensile test.The en-hanced mechanical properties and work hardening behavior were explained based on the transformation-induced plas-ticity effect of large-fractioned austenite.

  10. The effect of gamma-irradiation on the morphology of quenched isotactic polypropylene

    Science.gov (United States)

    Kostoski, D.; Stojanovic, Z.; Gal, O.; Stannett, V. T.

    Wide-angle X-ray diffraction, differential scanning calorimetry and gel-permeation chromatography measurements have been used to investigate the effect of low absorbed doses of γ-radiation, up to 100 kGy, on isotactic polypropylene (iPP). The bimodal endotherm for the sample quenched in iced water was attributed to the presence of both "smectic" and monoclinic crystalline phases. The changes in the morphology, molecular weight distribution, decrease of melting temperature and heat of fusion with absorbed dose are related to the radiation processes in pure iPP.

  11. SDSS-IV MaNGA: faint quenched galaxies - I. Sample selection and evidence for environmental quenching

    Science.gov (United States)

    Penny, Samantha J.; Masters, Karen L.; Weijmans, Anne-Marie; Westfall, Kyle B.; Bershady, Matthew A.; Bundy, Kevin; Drory, Niv; Falcón-Barroso, Jesús; Law, David; Nichol, Robert C.; Thomas, Daniel; Bizyaev, Dmitry; Brownstein, Joel R.; Freischlad, Gordon; Gaulme, Patrick; Grabowski, Katie; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Roman-Lopes, Alexandre; Pan, Kaike; Simmons, Audrey; Wake, David A.

    2016-11-01

    Using kinematic maps from the Sloan Digital Sky Survey (SDSS) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we reveal that the majority of low-mass quenched galaxies exhibit coherent rotation in their stellar kinematics. Our sample includes all 39 quenched low-mass galaxies observed in the first year of MaNGA. The galaxies are selected with Mr > -19.1, stellar masses 109 M⊙ 1.9. They lie on the size-magnitude and σ-luminosity relations for previously studied dwarf galaxies. Just six (15 ± 5.7 per cent) are found to have rotation speeds ve, rot 5 × 1010 M⊙), supporting the hypothesis that galaxy-galaxy or galaxy-group interactions quench star formation in low-mass galaxies. The local bright galaxy density for our sample is ρproj = 8.2 ± 2.0 Mpc-2, compared to ρproj = 2.1 ± 0.4 Mpc-2 for a star-forming comparison sample, confirming that the quenched low-mass galaxies are preferentially found in higher density environments.

  12. Mechanical properties of amorphous alloys ribbons prepared by rapid quenching of the melt after different thermal treatments before quenching

    NARCIS (Netherlands)

    Tabachnikova, ED; Bengus, VZ; Egorov, D V; Tsepelev, VS; Ocelik, Vaclav

    1997-01-01

    The mechanical properties of amorphous alloy are greatly influenced by the thermal treatment of its melt before rapid quenching. The strength and the fracture toughness of some amorphous alloys obtained after melt beating above the melt critical temperature T-CR are essentially higher than those obt

  13. SDSS-IV MaNGA: Faint quenched galaxies I- Sample selection and evidence for environmental quenching

    CERN Document Server

    Penny, Samantha J; Weijmans, Anne-Marie; Westfall, Kyle B; Bershady, Matthew A; Bundy, Kevin; Drory, Niv; Falcón-Barroso, Jesús; Law, David; Nichol, Robert C; Thomas, Daniel; Bizyaev, Dmitry; Brownstein, Joel R; Freischlad, Gordon; Gaulme, Patrick; Grabowski, Katie; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Roman-Lopes, Alexandre; Pan, Kaike; Simmons, Audrey; Wake, David A

    2016-01-01

    Using kinematic maps from the Sloan Digital Sky Survey (SDSS) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we reveal that the majority of low-mass quenched galaxies exhibit coherent rotation in their stellar kinematics. Our sample includes all 39 quenched low-mass galaxies observed in the first year of MaNGA. The galaxies are selected with $M_{r} > -19.1$, stellar masses $10^{9}$ M$_{\\odot} 1.9$. They lie on the size-magnitude and $\\sigma$-luminosity relations for previously studied dwarf galaxies. Just six ($15\\pm5.7$ per cent) are found to have rotation speeds $v_{e,rot} 5\\times10^{10}$ M$_{\\odot}$), supporting the hypothesis that galaxy-galaxy or galaxy-group interactions quench star formation in low-mass galaxies. The local bright galaxy density for our sample is $\\rho_{proj} = 8.2\\pm2.0$ Mpc$^{-2}$, compared to $\\rho_{proj} = 2.1\\pm0.4$ Mpc$^{-2}$ for a star forming comparison sample, confirming that the quenched low mass galaxies are preferentially found in higher density environ...

  14. Stability and quench of dual cooling channel cable-in-conduct superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Bertrand [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

    1999-11-01

    cooling channel NbTi CICCs with full-size ITER geometry. The influence of the central channel perforations on the stability margin of large CICCs is investigated experimentally. Four identical 3.6 m long pieces of NbTi CICC with ITER geometry but central channels with different porosities are used. The porosity ranges from about 50% with a spiral as central channel - like foreseen for the ITER conductors - over two differently perforated tubes with porosities of the order of 10{sup -2}%, to zero in the case of a smooth tube. All quench and stability tests have been performed in the SULTAN facility. No significant differences in stability between the conductor samples could be found for currents up to 50 kA, whereas at 60 kA a larger stability margin seemed to appear for the conductor with smallest porosity. These results suggest that for the kind of disturbances applied in the experiment and currents exceeding 50 kA the heating induced helium flow starts to become effective in terms of additional thermal stabilization, which is in agreement with the theoretical predictions made with a zero-dimensional analytical model. Premature quenching was observed in many quench experiments. Sudden voltage take-offs far below the expected critical current were observed without displaying any current sharing regime. The quench currents seemed to be determined by the limiting current, which describes the boundary above which only the marginal heat capacity of the strands can be utilized. These results were interpreted as an indication that thermal disturbances are continuously created by current redistribution processes among the strands due to a largely inhomogeneous current distribution over the cable cross section caused mainly by large interstrand contact resistances. The results of the heat slug measurements in combination with two-dimensional model calculations implied that the heat removal capabilities in long dual cooling channel cable-in-conduit conductors are determined only

  15. Quench Protection of the LHC Quadrupole Magnets

    CERN Document Server

    Kurfuerst, Christoph; Dehning, Bernd; Sapoinski, Mariusz

    2010-01-01

    CERNs Large Hadron Collider (LHC) is a new high energy proton accelerator and storage ring. Its design allows to reach unprecedented beam energies and beam intensities, resulting in a largely increased particle physics discovery potential. The combination of its high beam energy and intensity may lead to beam losses which can have a severe impact on the LHC equipment and damage sensitive elements. To protect those and to measure operational losses, a Beam Loss Monitoring system has been installed all along the ring. The protection is achieved by extracting the beam from the ring in case thresholds imposed on measured radiation levels are exceeded. The thresholds are estimated through particle shower simulations. The simulated geometry and physic processes need to be precise in order to determine an optimum value, which therefore assures a high availability of the LHC for operation. This study is focused on the interconnection region between the main dipole and the main quadrupole magnet of the LHC. Six monito...

  16. Characterization of silicon avalanche photodiodes for photon correlation measurements. 2: Active quenching.

    Science.gov (United States)

    Brown, R G; Jones, R; Rarity, J G; Ridley, K D

    1987-06-15

    We continue examination of the photon correlation properties of silicon avalanche photodiodes operated in photon-counting mode by extending their operation from that of passive quenching(1) to active quenching, yielding shorter dead time and higher frequency operation.

  17. Combined Quenching Mechanism of Anthracene Fluorescence by Cetylpyridinium Chloride in Sodium Dodecyl Sulfate Micelles.

    Science.gov (United States)

    Soemo, Angela R; Pemberton, Jeanne E

    2014-03-01

    The Stern-Volmer quenching constant (KSV) for quenching of anthracene fluorescence in sodium dodecyl sulfate (SDS) micelles by pyridinium chloride has been reported previously to be 520 M(-1) based on steady state fluorescence measurements. However, such measurements cannot distinguish static versus dynamic contributions to the overall quenching. In the work reported here, the quenching dynamics of anthracene in SDS micelles by cetylpyridinium chloride (CPC), an analogue of pyridinium chloride, were investigated using both steady state and time resolved fluorescence quenching. Concurrent measurement of the decrease in fluorescence intensity and lifetime of anthracene provide a quantitative evaluation of collision induced (i.e. dynamic) versus complex formation (i.e. static) quenching of the anthracene fluorophore. The results reveal that a combined quenching mechanism is operative with approximately equal constants of 249 ± 6 M(-1) and 225 ± 12 M(-1) for dynamic and static quenching, respectively.

  18. On The Enhancement of Wear Resistance of Hardened Carbon Tool Steel (AISI 1095) With Cryogenic Quenching

    Institute of Scientific and Technical Information of China (English)

    V.Soundararajan; N.Alagurmurthi; K.Palaniradja

    2004-01-01

    Many experimental investigations reveal that it is very difficult to have a completely martensitic structure by any hardening process. Some amount of austenite is generally present in the hardened steel. This austenite existing along with martensite is normally referred as the retained austenite. The presence of retained austenite greatly reduces the mechanical properties and such steels do not develop maximum hardness even after cooling at rates higher than the critical cooling rates.Strength can be improved in hardened steels containing retained austenite by a process known as cryogenic quenching.Untransformed austenite is converted into martensite by this treatment. This conversion of retained austenite into martensite results in increased hardness, wear resistance and dimensional stability of steel. Wear can be defined as the progressive loss of materials from the operating surface of a body occurring as a result of relative motion at the surface. Hardness, load,speed, surface roughness, temperature are the major factors which influences wear. Many studies on wear indicate that increasing hardness decreases the wear of a material. With this in mind, to study the surface wear on a surface modified(Cryogenic treated) steel material an attempt has been made in this paper. In this study as a Part -I Hardening was carried out on carbon tool steel (AISI 1095) of different L/D ratio with conventional quenchants like purified water, aqueous solution and Hot mineral oil. As a Part -Ⅱ hardening was followed by quenching was carried out as said in Part- I and the hardened specimen were quenched in liquid Nitrogen which is at sub zero condition. The specimens were tested for its microstructure, hardness and wear loss. The results were compared and analyzed. The alloying elements increases the content of retained austenite hence the material used was AISI1095 (Carbon 0.9%, Si 0.2%, Mn0.4% and the rest Iron)

  19. Measurement and Analysis of Bath-Side Interfacial Concentration Gradients during Membrane Quenching by Phase Inversion.

    Science.gov (United States)

    Gaides, Gary Edward

    A technique based on Fourier transform optical theory has been developed which allows for transient measurements of bath-side interfacial refractive index gradients during the quench step of membrane formation by phase inversion. From examination of individual Fourier components in a diffraction pattern associated with this one-dimensional mass transport process one is able to overcome the temporal and spatial resolution limitations imposed by many of the more traditional optical techniques. A first order expression relating the local refractive index gradient in the quench cell as a function of its measured spatial offset in the Fourier plane was derived for the purpose of determining the interfacial gradient which may be readily converted to individual species (solvent/nonsolvent) concentration gradients. Real-time interfacial gradients were able to be measured anywhere from 2 to 5 seconds after initiation of the quench using this technique. The r.m.s. errors associated with the reported interfacial species concentration gradient values were determined to range between 3% and 7% of the reported values for quench times less than 60 seconds. However, the reproducability of the experiment was shown to be well within these error limits. The bath-side interfacial refractive index gradient was measured as a function of time for both delayed (cellulose acetate in N,N-dimethylformamide with added nonsolvent ethanol) and instantaneous (cellulose acetate or polysulfone in N,N-dimethylformamide with added nonsolvent water) phase separation conditions with allowed variability in the following processing conditions: initial cast film thickness, initial solvent composition in the coagulation bath, initial nonsolvent composition in the casting solution, and initial polymer concentration in the casting solution. The directionality of the change associated with experimentally observed phenomena (bath-side interfacial solvent gradient and the time at which phase separation occurs

  20. An Artificial Neural Network Approach For Ranking Quenching Parameters In Central Galaxies

    CERN Document Server

    Teimoorinia, Hossen; Ellison, Sara L

    2016-01-01

    We present a novel technique for ranking the relative importance of galaxy properties in the process of quenching star formation. Specifically, we develop an artificial neural network (ANN) approach for pattern recognition and apply it to a population of over 400,000 central galaxies taken from the Sloan Digital Sky Survey Data Release 7. We utilise a variety of physical galaxy properties for training the pattern recognition algorithm to recognise star forming and passive systems, for a `training set' of $\\sim$100,000 galaxies. We then apply the ANN model to a `verification set' of $\\sim$100,000 different galaxies, randomly chosen from the remaining sample. The success rate of each parameter singly, and in conjunction with other parameters, is taken as an indication of how important the parameters are to the process(es) of central galaxy quenching. We find that central velocity dispersion, bulge mass and B/T are excellent predictors of the passive state of the system, indicating that properties related to the...

  1. PERHITUNGAN FLUKS KALOR UNTUK KURVA DIDIH SELAMA EKSPERIMEN QUENCHING MENGGUNAKAN SILINDER BERONGGA DIPANASKAN

    Directory of Open Access Journals (Sweden)

    Mulya Juarsa

    2015-04-01

    Full Text Available Salah satu aspek penting manajemen keselamatan dalam pengoperasian reaktor nuklir adalah manajemen termal. Konsep dasar pengelolaan termal adalah untuk mengendalikan kelebihan kalor saat terjadinya kecelakaan. Pemahaman dan investigasi fenomena pendidihan selama kecelakaan yang terjadi secara transien menjadi tahapan penelitian yang penting. Proses quenching adalah proses pendinginan tiba-tiba pada obyek yang panas dengan memasukkan ke dalam suatu fluida. Material SS316 dengan geometri silinder berongga pada posisi vertikal merupakan simulasi dari debris dan digunakan sebagai objek yang dipanaskan. Metode eksperimen dilakukan melalui pendinginan quenching secara alami pada silinder berongga dengan berbagai variasi temperatur awal dari 300 oC sampai 800 oC ke dalam temperatur saturasi air. Selama eksperimen data temperatur direkam dan visualisasi pendidihan dilakukan melalui kamera kecepatan tinggi (HSC. Hasil data transien temperatur digunakan untuk menghitung fluks kalor. Rejim didih film pada TC8 (bagian terluar dalam kurva didih untuk semua temperatur awal menunjukkan kesesuaian dengan korelasi Bromley. Proses didih film paling singkat terjadi selama 1,11 detik untuk temperatur awal 300 oC. Fluks kalor kritis pada TC8 untuk temperatur awal dari 800 oC, 600 oC, 400 oC dan 300 oC secara berturutturut adalah 700 kW/m2, 500 kW/m2, 450 kW/m2 dan 400 kW/m2. Kata kunci: quenching, silinder, pendidihan, fluks kalor   One of the safety management aspects in the operation of nuclear reactors is thermal management. The basic concept of thermal management is to control the excess heat during an accident. The understanding and investigation of boiling phenomenon become important research stage. Quenching process is the process of sudden cooling on a hot object by entering into a fluid. SS316 material with hollow cylinder geometry in a vertical position is the simulation of debris and used as a heated object. Method of quenching experiments carried out

  2. Effect of quenching rate on precipitation kinetics in AA2219 DC cast alloy

    Science.gov (United States)

    Elgallad, E. M.; Zhang, Z.; Chen, X.-G.

    2017-06-01

    Slow quenching of direct chill (DC) cast aluminum ingot plates used in large mold applications is often used to decrease quench-induced residual stresses, which can deteriorate the machining performance of these plates. Slow quenching may negatively affect the mechanical properties of the cast plates when using highly quench-sensitive aluminum alloys because of its negative effect on the precipitation hardening behavior of such alloys. The effect of the quenching rate on precipitation kinetics in AA2219 DC cast alloy was systematically studied under water and air quenching conditions using differential scanning calorimetry (DSC) technique. Transmission electron microscopy (TEM) was also used to characterize the precipitate microstructure. The results showed that the precipitation kinetics of the θ‧ phase in the air-quenched condition was mostly slower than that in the water-quenched one. Air quenching continuously increased the precipitation kinetics of the θ phase compared to water quenching. These results revealed the contributions of the inadequate precipitation of the strengthening θ‧ phase and the increased precipitation of the equilibrium θ phase to the deterioration of the mechanical properties of air-quenched AA2219 DC cast plates. The preexisting GP zones and quenched-in dislocations affected the kinetics of the θ‧ phase, whereas the preceding precipitation of the θ‧ phase affected the kinetics of the θ phase by controlling its precipitation mechanism.

  3. Galaxy Zoo: the interplay of quenching mechanisms in the group environment★

    Science.gov (United States)

    Smethurst, R. J.; Lintott, C. J.; Bamford, S. P.; Hart, R. E.; Kruk, S. J.; Masters, K. L.; Nichol, R. C.; Simmons, B. D.

    2017-08-01

    Does the environment of a galaxy directly influence the quenching history of a galaxy? Here, we investigate the detailed morphological structures and star formation histories of a sample of SDSS group galaxies with both classifications from Galaxy Zoo 2 and near ultra-violet (NUV) detections in GALEX. We use the optical and NUV colours to infer the quenching time and rate describing a simple exponentially declining star formation history for each galaxy, along with a control sample of field galaxies. We find that the time since quenching and the rate of quenching do not correlate with the relative velocity of a satellite but are correlated with the group potential. This quenching occurs within an average quenching time-scale of ∼ 2.5 Gyr from star forming to complete quiescence, during an average infall time (from ∼10R200 to 0.01R200) of ∼ 2.6 Gyr. Our results suggest that the environment does play a direct role in galaxy quenching through quenching mechanisms that are correlated with the group potential, such as harassment, interactions or starvation. Environmental quenching mechanisms that are correlated with satellite velocity, such as ram-pressure stripping, are not the main cause of quenching in the group environment. We find that no single mechanism dominates over another, except in the most extreme environments or masses. Instead, an interplay of mergers, mass and morphological quenching and environment-driven quenching mechanisms dependent on the group potential drive galaxy evolution in groups.

  4. Effect of quenching rate on precipitation kinetics in AA2219 DC cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elgallad, E.M., E-mail: eelgalla@uqac.ca; Zhang, Z.; Chen, X.-G.

    2017-06-01

    Slow quenching of direct chill (DC) cast aluminum ingot plates used in large mold applications is often used to decrease quench-induced residual stresses, which can deteriorate the machining performance of these plates. Slow quenching may negatively affect the mechanical properties of the cast plates when using highly quench-sensitive aluminum alloys because of its negative effect on the precipitation hardening behavior of such alloys. The effect of the quenching rate on precipitation kinetics in AA2219 DC cast alloy was systematically studied under water and air quenching conditions using differential scanning calorimetry (DSC) technique. Transmission electron microscopy (TEM) was also used to characterize the precipitate microstructure. The results showed that the precipitation kinetics of the θ′ phase in the air-quenched condition was mostly slower than that in the water-quenched one. Air quenching continuously increased the precipitation kinetics of the θ phase compared to water quenching. These results revealed the contributions of the inadequate precipitation of the strengthening θ′ phase and the increased precipitation of the equilibrium θ phase to the deterioration of the mechanical properties of air-quenched AA2219 DC cast plates. The preexisting GP zones and quenched-in dislocations affected the kinetics of the θ′ phase, whereas the preceding precipitation of the θ′ phase affected the kinetics of the θ phase by controlling its precipitation mechanism.

  5. On the polyphasic quenching kinetics of chlorophyll a fluorescence in algae after light pulses of variable length.

    Science.gov (United States)

    Vredenberg, Wim; Prasil, Ondrej

    2013-11-01

    This study reports on kinetics of the fluorescence decay in a suspension of the alga Scenedesmus quadricauda after actinic illumination. These are monitored as the variable fluorescence signal in the dark following light pulses of variable intensity and duration. The decay reflects the restoration of chlorophyll fluorescence quenching of the photosystem II (PSII) antennas and shows a polyphasic pattern which suggests the involvement of different processes. The overall quenching curve after a fluorescence-saturating pulse (SP) of 250-ms duration, commonly used in pulse amplitude modulation applications as the tool for estimating the maximal fluorescence (F m), has been termed P-O, in which P and O have the same meaning as used in the OJIP induction curve in the light. Deconvolution of this signal shows at least three distinguishable exponential phases with reciprocal rate constants of the order of 10, 10(2), and 10(3) ms. The size of the long (>10(3) ms) and moderate (~10(2) ms) lasting components relative to the complete quenching signal after an SP increases with the duration of the actinic pulse concomitantly with an increase in the reciprocal rate constants of the fast (~10 ms) and moderate quenching phases. Fluorescence responses upon single turnover flashes of 30-μs duration (STFs) given at discrete times during the P-O quenching were used as tools for identifying the quencher involved in the P-O quenching phase preceding the STF excitation. Results are difficult to interpret in terms of a single-hit two-state trapping mechanism with distinguishable quenching properties of open and closed reaction centers only. They give support for an earlier hypothesis on a double-hit three-state trapping mechanism in which the so-called semi-closed reaction centers of PSII are considered. In these trapping-competent centers the single reduced acceptor pair [PheQ A](1-), depending on the size of photoelectrochemically induced pH effects on the Q B-binding site

  6. Measuring oxygen pressures using triplet quenching of Pd-porphine

    Science.gov (United States)

    Sinaasappel, Michiel; Ince, C.; Sanderse, E. A.; Bruining, Hajo A.

    1994-02-01

    A non-invasive optical method for measuring free oxygen in vivo is described. The method, introduced by Wilson and co-workers, is based on the quenching of the triplet state of Pd- porphine by oxygen and is described by the Stern-Volmer relation. The quenching of the triplet state is determined by measurement of the phosphorescence decay following excitation by a pulse of light. Measuring decay times has the advantage that they are independent of the changing optical properties of tissue and concentration of the dye. We describe a setup to measure the phosphorescence decay and present the values of Kq and (tau) o as a function of pH and temperature. Furthermore, some experiments on a rat liver and gut are presented.

  7. Ionic quenching of naphthalene fluorescence in sodium dodecyl sulfate micelles.

    Science.gov (United States)

    Silva, Alessandra F; Fiedler, Haidi D; Nome, Faruk

    2011-03-31

    Micellar effects on luminescense of organic compounds or probes are well established, and here we show that quenching is highly favored in aqueous sodium dodecyl sulfate (SDS) micelles, which concentrate a naphthalene probe and cations of lanthanides, transition metals, and noble metals. Interactions have been studied by steady state and time-resolved fluorescence in examining the fluorescence suppression of naphthalene by metal ions in anionic SDS micelles. The quenching is collisional and correlated with the unit charge and the reduction potential of the metal ion. The rate constants, calculated in terms of local metal ion concentrations, are close to the diffusion control limit in the interior of SDS micelles, where the microscopic viscosity decreases the transfer rate, following the Stokes-Einstein relation.

  8. Phase separation in dense glassy liquids: effect of quenching protocols

    Science.gov (United States)

    Chaudhuri, Pinaki; Horbach, Jürgen

    2016-08-01

    Extensive molecular dynamics simulations are used to investigate the phase separation kinetics in a glass-forming binary Lennard-Jones mixture. The focus is on the two-phase region at low temperatures (i.e. below the glass transition line), where coexistence between a low-density gas with a metastable amorphous solid, i.e. a glass occurs. Two different quench paths are chosen to get into the two-phase region starting from a structurally homogeneous state, one along which temperature is lowered at a fixed density, and in the other case, the volume is expanded to reach lower densities at fixed temperatures. Both paths are explored by tuning the rates of cooling or expansion, respectively. We analyze thermodynamic and structural properties of the phase-separating systems, in particular with respect to differences in the morphologies that are obtained from the different quench protocols.

  9. Quenched disorder and spin-glass correlations in XY nematics

    Energy Technology Data Exchange (ETDEWEB)

    Petridis, L; Terentjev, E M [Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE (United Kingdom)

    2006-08-04

    We present a theoretical study of the equilibrium ordering in a 3D XY nematic system with quenched random disorder. Within this model, treated with the replica trick and Gaussian variational method, the correlation length is obtained as a function of the local nematic order parameter Q and the effective disorder strength {gamma}. These results, {xi} {approx} Q{sup 2}e{sup 1/Q{sup 2}} and {xi} {approx} (1/{gamma}) e{sup -{gamma}}, clarify what happens in the limiting cases of diminishing Q and {gamma}, that is near a phase transition of a pure system. In particular, it is found that quenched disorder is irrelevant as Q {yields} 0 and hence does not change the character of the continuous XY nematic-isotropic phase transition. We discuss how these results compare with experiments and simulations.

  10. $B_K$ from quenched QCD with exact chiral symmetry

    CERN Document Server

    Garron, N; Hölbling, C; Lellouch, L P; Rebbi, C; Garron, Nicolas; Giusti, Leonardo; Hoelbling, Christian; Lellouch, Laurent; Rebbi, Claudio

    2004-01-01

    We present a calculation of the standard model Delta S=2 matrix element relevant to indirect CP violation in K->pipi decays which uses Neuberger's chiral formulation of lattice fermions. The computation is performed in the quenched approximation on a 16^3x32 lattice that has a lattice spacing asim 0.1 fm. The resulting bare matrix element is renormalized non-perturbatively. Our main result is B_K^{RGI}=0.87(8)^{+2+14}_{-1-14}, where the first error is statistical, the second is systematic and the third is an estimate of the uncertainty associated with the quenched approximation and with the fact that our kaons are composed of degenerate s and d quarks with masses sim m_s/2.

  11. Intermolecular-charge-transfer-induced fluorescence quenching in protic solvent

    Science.gov (United States)

    Lin, Tao; Liu, Xiaojun; Lou, Zhidong; Hou, Yanbing; Teng, Feng

    2016-11-01

    The fluorescence quenching of fluorenone in protic solvent has been extensively investigated, and the intermolecular hydrogen bond was found to play a crucial role. Unfortunately, the mechanism at atomic level is still not clear. In the present work, we theoretically put forward the charge transfer along the hydrogen bond in the excited states. The vertical excitation energies of the fluorenone-methanol complex as well as the potential energy profiles and surfaces of the vertical excited states and charge transfer states were calculated by using the ab initio electronic-structure methods. The photochemical reactions occurring in the diverse charge transfer states were compared and their decisiveness to the fluorescence quenching was discussed in the paper.

  12. Phases formed during rapid quenching of liquid carbon

    Science.gov (United States)

    Basharin, A. Yu.; Dozhdikov, V. S.; Dubinchuk, V. T.; Kirillin, A. V.; Lysenko, I. Yu.; Turchaninov, M. A.

    2009-05-01

    Pulsed laser action upon a sample of highly oriented pyrolytic graphite (HOPG) in a gasostat filled with helium at a pressure above that corresponding to the triple point of carbon, followed by rapid quenching of the liquid phase at a rate of about 106 K/s leads to the formation of a crater with a periodic spatial structure at the surface. The composition and structure of nongraphite carbon phases in the near-surface region of the crater have been studied using the Raman scattering spectroscopy, electron microdiffraction, and energy-dispersive X-ray analysis. It is established that rapidly quenched carbon possesses predominantly a hybrid structure of glassy carbon formed as a result of the high-temperature treatment, with inclusions of crystalline carbyne, chaoite, and a hybrid cubic phase of ultradense carbon (C8). The hybrid phases of glassy carbon and C8 had not been reported until now as possible products of solidification of liquid carbon.

  13. Thermodynamic analysis of fluorescence enhancement and Quenching theory equations

    Institute of Scientific and Technical Information of China (English)

    Manman YANG; Xiaoli XI; Pin YANG

    2008-01-01

    The action of the three kinds of new third generation cephalosporin,class drugs,cefepime hydrochroride,cefpiramide and ceftizoxime with HSA and BSA was studied at different temperatures through the fluorescence method. First,the binding constants were calculated by using fluorescence quenching and enhancement theoretical equations. Their thermodynamic functions were also calculated. Because the KA corresponding to the different theoretical equations are not completely the same,the thermodynamic parameters calculated are also different. In this paper,the differences among these thermodynamic data obtained from the different theoretical equations were analyzed and the results show that the thermodynamic data deduced from fluorescence enhancement are more reasonable. Thus,we propose that even when the fluorescence quenching action of the acceptorsubstrate is studied,more realistic data can be obtained by using the fluorescence enhancement equation.

  14. Mutual information after a local quench in conformal field theory

    CERN Document Server

    Asplund, Curtis T

    2013-01-01

    We compute the entanglement entropy and mutual information for two disjoint intervals in two-dimensional conformal field theories as a function of time after a local quench, using the replica trick and boundary conformal field theory. We obtain explicit formulae for the universal contributions, which are leading in the regimes of, for example, close or well-separated intervals of fixed length. The results are largely consistent with the quasiparticle picture, in which entanglement above that present in the ground state is carried by pairs of entangled, freely propagating excitations. We also calculate the mutual information for two disjoint intervals in a proposed holographic local quench, whose holographic energy-momentum tensor matches the conformal field theory one. We find that the holographic mutual information shows qualitative differences from the conformal field theory results and we discuss possible interpretations of this.

  15. Fluids in porous media. IV. Quench effect on chemical potential

    Science.gov (United States)

    Qiao, C. Z.; Zhao, S. L.; Liu, H. L.; Dong, W.

    2017-06-01

    It appears to be a common sense to measure the crowdedness of a fluid system by the densities of the species constituting it. In the present work, we show that this ceases to be valid for confined fluids under some conditions. A quite thorough investigation is made for a hard sphere (HS) fluid adsorbed in a hard sphere matrix (a quench-annealed system) and its corresponding equilibrium binary mixture. When fluid particles are larger than matrix particles, the quench-annealed system can appear much more crowded than its corresponding equilibrium binary mixture, i.e., having a much higher fluid chemical potential, even when the density of each species is strictly the same in both systems, respectively. We believe that the insight gained from this study should be useful for the design of functionalized porous materials.

  16. Microstructures developed by super-rapid induction heating-and-quenching (SRIHQ) of Fe–1.4%Cr–1%C pearlitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Koizumi, Yuichiro, E-mail: koizumi@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Otsuka, Takeshi; Minamino, Yoritoshi [Department of Adaptive Machine Systems, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Takayama, Takemori; Ueyama, Masanori [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Manufacturing Engineering Development Center, Komatsu Ltd., 3-1-1 Ueno, Hirakata, Osaka 573-1011 (Japan); Daio, Takeshi [Research Laboratory for High-Voltage Electron Microscopy, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Hata, Satoshi [Department of Molecular and Materials Science, Kyushu University, 6-1 Kasuga-kouen, Kasuga, Fukuoka 816-8580 (Japan)

    2013-08-10

    Microstructures and hardness of a Fe–1.4%Cr–1%C pearlitic steel processed by super-rapid induction heating-and-quenching (SRIHQ) under various conditions have been investigated. A nano-scaled laminated microstructure composed of two different types of martensite (highly-twinned or containing a high dislocation density) was formed and the maximum hardness was obtained by heating to 1223 K in 0.5 s and quenched. Electron energy loss spectroscopy indicated that the two different types of martensite were formed depending on the local solute-concentration in the non-uniform solute-distribution realized by the SRIHQ-process.

  17. Jet quenching and high-pt azimuthal asymmetry

    CERN Document Server

    Lokhtin, Igor P; Vitev, I

    2002-01-01

    The azimuthal anisotropy of high-pt particle production in non-central heavy ion collisions is among the most promising observables of partonic energy loss in an azimuthally non-symmetric volume of quark-gluon plasma. We discuss the implications of nuclear geometry for the models of partonic energy loss in the context of recent RHIC data and consequences for observation of jet quenching at the LHC.

  18. Light hadron spectrum and decay constants in quenched lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Allton, C.R.; Lellouch, L.; Sachrajda, C.T.; Wittig, H. (Physics Department, The University, Southampton SO9 5NH (United Kingdom)); Baxter, R.M.; Booth, S.P.; Bowler, K.C.; Henty, D.S.; Kenway, R.D.; McNeile, C.; Pendleton, B.J.; Richards, D.G.; Simone, J.N.; Simpson, A.D. (Department of Physics, The University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)); (UKQCD Collaboration)

    1994-01-01

    We present results for light hadrons composed of both degenerate and nondegenerate quarks in quenched lattice QCD. We calculate masses and decay constants using 60 gauge configurations with an [ital O]([ital a])-improved fermion action at [beta]=6.2. Using the [rho] mass to set the scale we find hadron masses within two to three standard deviations of the experimental values (given in parentheses): [ital m][sub [ital K

  19. Hadron masses and decay constants in quenched QCD

    CERN Document Server

    Göckeler, M; Petters, D; Pleiter, D; Rakow, P E L; Schierholz, G; Stephenson, P

    2000-01-01

    We present results for the mass spectrum and decay constants using non-perturbatively O(a) improved Wilson fermions. Three values of beta and 30 different quark masses are used to obtain the chiral and continuum limits. Special emphasis will be given to the question of taking the chiral limit and the existence of non-analytic behavior predicted by quenched chiral perturbation theory (qxPT).

  20. Quenched hadron spectroscopy with improved staggered quark action

    CERN Document Server

    Bernard, C W; DeGrand, T A; DeTar, C E; Gottlieb, S; Heller, U M; Hetrick, J E; McNeile, C; Rummukainen, K; Sugar, B; Toussaint, D; Bernard, Claude; Blum, Tom; Grand, Thomas A. De; Tar, Carleton De; Gottlieb, Steven; Heller, Urs M.; Hetrick, James; Neile, Craig Mc; Sugar, Bob; Toussaint, Doug

    1998-01-01

    We investigate light hadron spectroscopy with an improved quenched staggered quark action. We compare the results obtained with an improved gauge plus an improved quark action, an improved gauge plus standard quark action, and the standard gauge plus standard quark action. Most of the improvement in the spectroscopy results is due to the improved gauge sector. However, the improved quark action substantially reduces violations of Lorentz invariance, as evidenced by the meson dispersion relations.