Aquifer/aquitard interfaces: mixing zones that enhance biogeochemical reactions

Science.gov (United States)

McMahon, P. B.

2001-01-01

Several important biogeochemical reactions are known to occur near the interface between aquifer and aquitard sediments. These reactions include O2 reduction; denitrification; and Fe3+, SO42-, and CO2 (methanogenesis) reduction. In some settings, these reactions occur on the aquitard side of the interface as electron acceptors move from the aquifer into the electron-donor-enriched aquitard. In other settings, these reactions occur on the aquifer side of the interface as electron donors move from the aquitard into the electron-acceptor-enriched, or microorganism-enriched, aquifer. Thus, the aquifer/aquitard interface represents a mixing zone capable of supporting greater microbial activity than either hydrogeologic unit alone. The extent to which biogeochemical reactions proceed in the mixing zone and the width of the mixing zone depend on several factors, including the abundance and solubility of electron acceptors and donors on either side of the interface and the rate at which electron acceptors and donors react and move across the interface. Biogeochemical reactions near the aquifer/aquitard interface can have a substantial influence on the chemistry of water in aquifers and on the chemistry of sediments near the interface. Résumé. Il se produit au voisinage de l'interface entre les aquifères et les imperméables plusieurs réactions biogéochimiques importantes. Il s'agit des réactions de réduction de l'oxygène, de la dénitrification et de la réduction de Fe3+, SO42- et CO2 (méthanogenèse). Dans certaines situations, ces réactions se produisent du côté imperméable de l'interface, avec des accepteurs d'électrons qui vont de l'aquifère vers l'imperméable riche en donneurs d'électrons. Dans d'autres situations, ces réactions se produisent du côté aquifère de l'interface, avec des donneurs d'électrons qui se déplacent de l'imperméable vers l'aquifère riche en accepteurs d'électrons ou en microorganismes. Ainsi, l'interface aquif

Ultrasonographic Evaluation of Zone II Partial Flexor Tendon Lacerations of the Fingers: A Cadaveric Study.

Science.gov (United States)

Kazmers, Nikolas H; Gordon, Joshua A; Buterbaugh, Kristen L; Bozentka, David J; Steinberg, David R; Khoury, Viviane

2018-04-01

Accurate assessment of zone II partial flexor tendon lacerations in the finger is clinically important. Surgical repair is recommended for lacerations of greater than 50% to 60%. Our goal was to evaluate ultrasonographic test characteristics and accuracy in identifying partial flexor tendon lacerations in a cadaveric model. From fresh-frozen above-elbow human cadaveric specimens, 32 flexor digitorum profundus tendons were randomly selected to remain intact or receive low- or high-grade lacerations involving 10% to 40% and 60% to 90% of the radioulnar width within Verdan Zone II, respectively. Static and dynamic ultrasonography using a linear array 14-MHz transducer was performed by a blinded musculoskeletal radiologist. Sensitivities, specificities, and other standard test performance metrics were calculated. Actual and measured percentages of tendon laceration were compared by the paired t test. After randomization, 24 tendons were lacerated (12 low- and 12 high-grade), whereas 8 remained intact. The sensitivity and specificity in detecting the presence versus absence of a partial laceration were 0.54 and 0.75, respectively, with positive and negative likelihood ratio values of 2.17 and 0.61. For low-grade lacerations, the sensitivity and specificity were 0.25 and 0.85, compared to 0.83 and 0.85 for high-grade lacerations. Ultrasonography underestimated the percentage of tendon involvement by a mean of 18.1% for the study population as a whole (95% confidence interval, 9.0% to 27.2%; P partial flexor digitorum profundus lacerations in a cadaveric model. © 2017 by the American Institute of Ultrasound in Medicine.

Partial oxidation of jet fuels over Rh/Al_2O_3. Design and reaction kinetics of sulfur-containing surrogates

International Nuclear Information System (INIS)

Baer, Julian Nicolaas

2016-01-01

increase in water selectivity and decrease in hydrogen selectivity are observed. The carbon-based main product distribution does not change. Concerning the deactivation process in the presence of sulfur, adding sulfur leads to an immediate decline in the reaction rate of steam reforming. These conclusions gained in the ex-situ study are confirmed by in-situ studies, in which a more detailed insight into the reaction sequence of the CPOX of higher hydrocarbons is provided. The reaction sequence of catalytic partial oxidation of the pure substances n-dodecane and 1,2,4-trimethylbenzene as well as the surrogate blend shows a more complex reaction network compared to methane. Decomposition reactions of the hydrocarbons and their limited diffusion rate lead to the deployment of three reaction zones and a delayed oxygen consumption. Sulfur deactivation very likely occurs in the part of the catalyst in which oxygen is completely consumed, leading to the observed shift in water-to-hydrogen product ratio and the smaller reaction rate of steam reforming.

Spatially resolved Raman spectroscopy study of transformed zones in magnesia-partially-stabilized zirconia

International Nuclear Information System (INIS)

Davskardt, R.H.; Veirs, D.K.; Ritchie, R.O.

1989-01-01

Raman vibrational spectroscopy provides an effective phase characterization technique in materials systems containing particle dispersions of the tetragonal and monoclinic polymorphs of zirconia, each of which yields a unique Raman spectrum. An investigation is reported to assess a novel, spatially resolved Raman spectroscopy system in the study of transformed zones surrounding cracks in partially stabilized MgO-ZrO 2 (PSZ). The experimental arrangement uses an imaging (two-dimensional) photomultiplier tube to produce a one-dimensional Raman profile of phase compositions along a slitlike laser beam without translation of either the sample or the laser beam and without scanning the spectrometer. Results from phase characterization studies of the size, frontal morphology, and extent of transformation of transformation zones surrounding cracks produced under monotonic and cyclic loading conditions are presented

Structure of Unsteady Partially Premixed Flames and the Existence of State Relationships

Directory of Open Access Journals (Sweden)

Suresh K. Aggarwal

2009-09-01

Full Text Available In this study, we examine the structure and existence of state relationships in unsteady partially premixed flames (PPFs subjected to buoyancy-induced and external perturbations. A detailed numerical model is employed to simulate the steady and unsteady two-dimensional PPFs established using a slot burner under normal and zero-gravity conditions. The coflow velocity is parametrically varied. The methane-air chemistry is modeled using a fairly detailed mechanism that contains 81 elementary reactions and 24 species. Validation of the computational model is provided through comparisons of predictions with nonintrusive measurements. The combustion proceeds in two reaction zones, one a rich premixed zone and the other a nonpremixed zone. These reaction zones are spatially separated, but involve strong interactions between them due to thermochemistry and scalar transport. The fuel is mostly consumed in the premixed zone to produce CO and H2, which are transported to and consumed in the nonpremixed zone. The nonpremixed zone in turn provides heat and H-atoms to the premixed zone. For the range of conditions investigated, the zero-g partially premixed flames exhibit a stable behavior and a remarkably strong resistance to perturbations. In contrast, the corresponding normal-gravity flames exhibit oscillatory behavior at low coflow velocities but a stable behavior at high coflow velocities, and the behavior can be explained in terms of a global and convective instabilities. The effects of coflow and gravity on the flames are characterized through a parameter VR, defined as the ratio of coflow velocity to jet velocity. For VR ≤ 1 (low coflow velocity regime, the structures of both 0- and 1-g flames are strongly sensitive to changes in VR, while they are only mildly affected by coflow in the high coflow velocity regime (VR > 1. In addition, the spatio-temporal characteristics of the 0- and 1-g flames are markedly different in the first regime, but are

Fundamental studies on the reaction process of partial hydropyrolysis of coal

Energy Technology Data Exchange (ETDEWEB)

O. Yamada; H. Yasuda; M. Kaiho [National Institute of Advanced Industrial Science and Technology, Ibaraki (Japan). Energy Technology Research Institute

2005-07-01

In order to make up a simulator to support the development of coal partial hydropyrolysis process, material balance of the reaction was investigated precisely. Amount of H{sub 2} evolved by pyrolysis under inert gas atmosphere was found almost equal to that of (CO+2CO{sub 2}), therefore, most of H{sub 2} seemed to be generated through water gas reaction and shift reaction. CH{sub 4} seemed to be stable even at 1073K and 7.1MPa of H{sub 2}, its generation was simply accelerated in proportion to H{sub 2} pressure. Hydrocarbons, other than CH{sub 4}, were fundamentally unstable at 1073K and 0.93 -7.1MPa of H{sub 2}, however the rate of decomposition of them were so slow that amounts of them evolved were apparently proportion to reaction time and H{sub 2} pressure. BTX and naphthalene were increased apparently with H{sub 2} pressure when the reaction time was less than 5s. 4 refs., 20 figs.

Experimental investigations of different steel resistances in the sodium-steam reaction zone

International Nuclear Information System (INIS)

Mazanov, A.S.; Kulpin, B.V.; Petukhov, V.P.; Ledovskikh, N.M.

1975-01-01

The results are stated on the experimental investigations of IX2M, IXI8HIOT, OXI2H2M and Sanikro-31 steel resistance in the sodium-steam reaction zone. A target in the form of a pipe was used in the experiments within which the excessive pressure of 95 atm. was produced with an inert gas. Steam was supplied through the nozzle to the sodium tank in which there was a movable target unit. The dependence of time-to failure and failure rate on the distance of the nozzle and target wall thickness was estimated for these steels. It was shown that the resistance of Sanikro-31 in the sodium steam reaction zone was 2.5, 3.5 and 6 times that of IXI8HIOT, OXI2H2M, IX2M steels, respectively. The failure curves were obtained on thin targets for two steels (author)

Influence of buffer zone concentrations on efficiency in partial filling micellar electrokinetic chromatography.

Science.gov (United States)

Michalke, D; Kolb, S; Welsch, T

2001-05-04

The potential of counter pressure-moderated partial filling micellar electrokinetic chromatography (PF-MEKC) was investigated in this work. Plate numbers of homologous omega-phenylalcohols were measured in a two-plug PF-MEKC system varying the concentrations and hence the ionic strengths of the background buffer compared to the sodium dodecyl sulfate-containing separation buffer and the counter pressure on the cathodic buffer reservoir. It was observed that plate numbers are strongly influenced by both the buffer concentrations and the counter pressure. Highest plate numbers were obtained with a buffer system where the concentrations are adjusted such that the electroosmotic flow velocities in both zones are equal. Differences in the local electroosmotic flow velocities of the zones caused by different buffer concentrations are responsible for tremendously reduced plate numbers. The efficiency drop is explained in several models by the formation of an intersegmental pressure which produces a parabolically shaped laminar flow component in both zones. Thus, the electroosmotic plug-like flow profile is distorted and the efficiency is reduced. The effect of counter pressure on efficiency turned out to be very complex in dependence on the buffer system applied.

Rebound of a coal tar creosote plume following partial source zone treatment with permanganate.

Science.gov (United States)

Thomson, N R; Fraser, M J; Lamarche, C; Barker, J F; Forsey, S P

2008-11-14

The long-term management of dissolved plumes originating from a coal tar creosote source is a technical challenge. For some sites stabilization of the source may be the best practical solution to decrease the contaminant mass loading to the plume and associated off-site migration. At the bench-scale, the deposition of manganese oxides, a permanganate reaction byproduct, has been shown to cause pore plugging and the formation of a manganese oxide layer adjacent to the non-aqueous phase liquid creosote which reduces post-treatment mass transfer and hence mass loading from the source. The objective of this study was to investigate the potential of partial permanganate treatment to reduce the ability of a coal tar creosote source zone to generate a multi-component plume at the pilot-scale over both the short-term (weeks to months) and the long-term (years) at a site where there is >10 years of comprehensive synoptic plume baseline data available. A series of preliminary bench-scale experiments were conducted to support this pilot-scale investigation. The results from the bench-scale experiments indicated that if sufficient mass removal of the reactive compounds is achieved then the effective solubility, aqueous concentration and rate of mass removal of the more abundant non-reactive coal tar creosote compounds such as biphenyl and dibenzofuran can be increased. Manganese oxide formation and deposition caused an order-of-magnitude decrease in hydraulic conductivity. Approximately 125 kg of permanganate were delivered into the pilot-scale source zone over 35 days, and based on mass balance estimates 35% reduction for all monitored compounds except for biphenyl, dibenzofuran and fluoranthene 150 days after treatment, which is consistent with the bench-scale experimental results. Pre- and post-treatment soil core data indicated a highly variable and random spatial distribution of mass within the source zone and provided no insight into the mass removed of any of the

Metasomatic Reaction Zones as Monitors of Trace Element Transfer at the Slab-Mantle Interface: the Case of the Hochwart Peridotite (Ulten Zone, Italy)

Science.gov (United States)

Marocchi, M.; Hermann, J.; Bargossi, G. M.; Mair, V.; Morten, L.

2006-12-01

phases (phlogopite and amphibole) in different metasomatic zones indicate mobility of many elements, including elements such as Ta which are considered to have scarce mobility in fluids. Trace element composition of accessory minerals in the phlogopite-rich zone suggests that the trace element signature of subduction zone fluids may be fractionated in this zone. The progressive depletion in some trace elements (LREE) and enrichment in LILE and Li from the peridotite towards the gneiss suggests a strong influence of bulk composition on the trace element budget of hydrous minerals. Since the ultramafic blocks can be representative of metasomatic processes occurring at the slab-mantle interface, we can infer that metasomatic reactions between slab-derived fluids and ultramafic mantle wedge will follow a specific series of reactions, creating mineral zonation similar to those observed in this study. Our results further favour the evidence that the primary composition of subduction zone fluids is modified substantially by metasomatic reactions occurring in the mantle wedge.

Controls of faulting and reaction kinetics on serpentinization and double Benioff zones

OpenAIRE

Iyer, Karthik; Rüpke, Lars H.; Phipps Morgan, Jason; Grevemeyer, Ingo

2012-01-01

The subduction of partially serpentinized oceanic mantle may potentially be the key geologic process leading to the regassing of Earth's mantle and also has important consequences for subduction zone processes such as element cycling, slab deformation, and intermediate-depth seismicity. However, little is known about the quantity of water that is retained in the slab during mantle serpentinization and the pattern of serpentinization that may occur during bending-related faulting; an initial s...

Partial oxidation of jet fuels over Rh/Al{sub 2}O{sub 3}. Design and reaction kinetics of sulfur-containing surrogates

Energy Technology Data Exchange (ETDEWEB)

Baer, Julian Nicolaas

2016-07-01

distribution. An increase in water selectivity and decrease in hydrogen selectivity are observed. The carbon-based main product distribution does not change. Concerning the deactivation process in the presence of sulfur, adding sulfur leads to an immediate decline in the reaction rate of steam reforming. These conclusions gained in the ex-situ study are confirmed by in-situ studies, in which a more detailed insight into the reaction sequence of the CPOX of higher hydrocarbons is provided. The reaction sequence of catalytic partial oxidation of the pure substances n-dodecane and 1,2,4-trimethylbenzene as well as the surrogate blend shows a more complex reaction network compared to methane. Decomposition reactions of the hydrocarbons and their limited diffusion rate lead to the deployment of three reaction zones and a delayed oxygen consumption. Sulfur deactivation very likely occurs in the part of the catalyst in which oxygen is completely consumed, leading to the observed shift in water-to-hydrogen product ratio and the smaller reaction rate of steam reforming.

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

Directory of Open Access Journals (Sweden)

Carmen Moreno-Marrodan

2017-04-01

Full Text Available The catalytic partial hydrogenation of substituted alkynes to alkenes is a process of high importance in the manufacture of several market chemicals. The present paper shortly reviews the heterogeneous catalytic systems engineered for this reaction under continuous flow and in the liquid phase. The main contributions appeared in the literature from 1997 up to August 2016 are discussed in terms of reactor design. A comparison with batch and industrial processes is provided whenever possible.

Partial Root-Zone Drying of Olive (Olea europaea var. 'Chetoui' Induces Reduced Yield under Field Conditions.

Directory of Open Access Journals (Sweden)

Soumaya Dbara

Full Text Available The productivity of olive trees in arid and semi-arid environments is closely linked to irrigation. It is necessary to improve the efficiency of irrigation techniques to optimise the amount of olive fruit produced in relation to the volume of water used. Partial root-zone drying (PRD is a water saving irrigation technique that theoretically allows the production of a root-to-shoot signal that modifies the physiology of the above-ground parts of the plant; specifically reducing stomatal conductance (gs and improving water use efficiency (WUE. Partial root-zone drying has been successfully applied under field conditions to woody and non-woody crops; yet the few previous trials with olive trees have produced contrasting results. Thirty year-old olive trees (Olea europaea 'var. Chetoui' in a Tunisian grove were exposed to four treatments from May to October for three-years: 'control' plants received 100% of the potential evapotranspirative demand (ETc applied to the whole root-zone; 'PRD100' were supplied with an identical volume of water to the control plants alternated between halves of the root-zone every ten-days; 'PRD50' were given 50% of ETc to half of the root-system, and; 'rain-fed' plants received no supplementary irrigation. Allowing part of the root-zone to dry resulted in reduced vegetative growth and lower yield: PRD100 decreased yield by ~47% during productive years. During the less productive years of the alternate bearing cycle, irrigation had no effect on yield; this suggests that withholding of water during 'off-years' may enhance the effectiveness of irrigation over a two-year cycle. The amount and quality of oil within the olive fruit was unaffected by the irrigation treatment. Photosynthesis declined in the PRD50 and rain-fed trees due to greater diffusive limitations and reduced biochemical uptake of CO2. Stomatal conductance and the foliar concentration of abscisic acid (ABA were not altered by PRD100 irrigation, which may

Partial Root-Zone Drying of Olive (Olea europaea var. 'Chetoui') Induces Reduced Yield under Field Conditions.

Science.gov (United States)

Dbara, Soumaya; Haworth, Matthew; Emiliani, Giovani; Ben Mimoun, Mehdi; Gómez-Cadenas, Aurelio; Centritto, Mauro

2016-01-01

The productivity of olive trees in arid and semi-arid environments is closely linked to irrigation. It is necessary to improve the efficiency of irrigation techniques to optimise the amount of olive fruit produced in relation to the volume of water used. Partial root-zone drying (PRD) is a water saving irrigation technique that theoretically allows the production of a root-to-shoot signal that modifies the physiology of the above-ground parts of the plant; specifically reducing stomatal conductance (gs) and improving water use efficiency (WUE). Partial root-zone drying has been successfully applied under field conditions to woody and non-woody crops; yet the few previous trials with olive trees have produced contrasting results. Thirty year-old olive trees (Olea europaea 'var. Chetoui') in a Tunisian grove were exposed to four treatments from May to October for three-years: 'control' plants received 100% of the potential evapotranspirative demand (ETc) applied to the whole root-zone; 'PRD100' were supplied with an identical volume of water to the control plants alternated between halves of the root-zone every ten-days; 'PRD50' were given 50% of ETc to half of the root-system, and; 'rain-fed' plants received no supplementary irrigation. Allowing part of the root-zone to dry resulted in reduced vegetative growth and lower yield: PRD100 decreased yield by ~47% during productive years. During the less productive years of the alternate bearing cycle, irrigation had no effect on yield; this suggests that withholding of water during 'off-years' may enhance the effectiveness of irrigation over a two-year cycle. The amount and quality of oil within the olive fruit was unaffected by the irrigation treatment. Photosynthesis declined in the PRD50 and rain-fed trees due to greater diffusive limitations and reduced biochemical uptake of CO2. Stomatal conductance and the foliar concentration of abscisic acid (ABA) were not altered by PRD100 irrigation, which may indicate the

Effect of partial root zone drying and deficit irrigation on nitrogen and phosphorus uptake in potato

DEFF Research Database (Denmark)

Liu, Caixia; Rubæk, Gitte Holton; Liu, Fulai

2015-01-01

Better understanding of the effects of deficit irrigation regimes on phosphorus (P) and nitrogen (N) uptake dynamics is necessary for sustainable water, P and N management. The effects of full (FI), deficit (DI) and partial root-zone drying (PRD) irrigation on potato P and N uptake with P fertili...... was superior to DI in terms of N uptake, but not P uptake. Challenges remain how to maintain crop yield and P uptake under reduced irrigation regimes. Utilization of water and N fertilizer was low when the soil was deficient in P.......Better understanding of the effects of deficit irrigation regimes on phosphorus (P) and nitrogen (N) uptake dynamics is necessary for sustainable water, P and N management. The effects of full (FI), deficit (DI) and partial root-zone drying (PRD) irrigation on potato P and N uptake with P...... fertilization (P1) or without (P0) were investigated in two split-root pot experiments in a soil with low plant available P. Under FI, the plants were irrigated to pot water holding capacity while under DI and PRD, 70% of the water amount of FI was applied on either both or one side of the pots, respectively...

Nitrogen dynamics in the soil-plant system under deficit and partial root-zone drying irrigation strategies in potatoes

DEFF Research Database (Denmark)

Shahnazari, Ali; Ahmadi, Seyed Hamid; Lærke, Poul Erik

2008-01-01

Experiments were conducted in lysimeters with sandy soil under an automatic rain-out shelter to study the effects of subsurface drip irrigation treatments, full irrigation (FI), deficit irrigation (DI) and partial root-zone drying (PRD), on nitrogen (N) dynamics in the soil-plant system of potatoes...

Effect of sulfur dioxide partial pressure on the reaction of iodine, sulfur dioxide and water

International Nuclear Information System (INIS)

Nakajima, Hayato; Imai, Yoshiyuki; Kasahara, Seiji; Kubo, Shinji; Onuki, Kaoru

2007-01-01

Effect of sulfur dioxide partial pressure on the reaction of iodine, sulfur dioxide and water, which is a unit reaction in the IS process for thermochemical hydrogen production, was studied experimentally at 323 K under iodine saturation. Quasi-equilibrium state was observed in the presence of sulfur dioxide gas at constant pressure. The composition of the poly-hydriodic acid solution formed was discussed assuming an ideal desulfurization by the reverse reaction of the Bunsen reaction. The value of HI/(HI+H 2 O) of the desulfurized solution was large at high sulfur dioxide pressure and reached the maximum of 15.7 ± 0.3 mol%. (author)

Partial wave analysis of the 18O(p,α0)15N reaction

International Nuclear Information System (INIS)

Wild, L.W.J.; Spicer, B.M.

1979-01-01

A partial wave analysis of the differential cross sections for the 18 O(p,α 0 ) 15 N reaction has been carried out applying the formalism of Blatt and Biedenharn (1952), made specific for this reaction. The differential cross sections, measured at 200 keV intervals from 6.6 to 10.4 MeV bombarding energy, were subjected to least-squares fitting to this specific analytic expression. Two resonances were given by the analysis, the 19 F states being at 14.71+-0.07 MeV (1/2 - ) and 14.80 + 0.07 MeV (1/2) +

Comparative effects of partial root-zone drying and deficit irrigation on nitrogen uptake in potatoes (Solanum tuberosum L.)

DEFF Research Database (Denmark)

Wang, Huiqun; Liu, Fulai; Andersen, Mathias Neumann

2009-01-01

The effects of partial root-zone drying (PRD) as compared with deficit irrigation (DI) and full irrigation (FI) on nitrogen (N) uptake and partitioning in potato (Solanum tuberosum L.) were investigated. Potato plants were grown in split-root pots and were exposed to FI, PRD, and DI treatments...

Early structure of LPG partially premixed conically stabilized flames

KAUST Repository

Elbaz, Ayman M.

2013-01-01

This paper presents experimental investigation of LPG partially premixed turbulent flames stabilized within a conical nozzle burner under constant degree of partial premixing. The stability limits and mean flame structure are presented based on the mean gas temperature and the concentration of CO, O 2, NO, and HC at the flame early region of reaction. The investigation covered the influence of the nozzle cone angle, the jet exit velocity and the jet equivalence ratio. The stability results show that the flames with cone are more stable than those without cone. For conical stabilized flames, the stability results exhibit three different sensitivity regions between the jet velocity and equivalence ratio. The inflame measurements prove that the flame stability could be attributed to the triple flame structure at the flame leading edge. The data show that the triple flame structure is influenced by cone angle, the jet velocity and the equivalence ratio. The flame is believed to be controlled by the recirculation flow inside the cone. Increasing the cone angle induced higher air entrainment to the reaction zone as depicted by a higher O 2 concentration within the flame leading edge. Increasing the jet velocity to a certain limit enhances the intensity of combustion at the flame leading edge, while excessive increase in jet velocity reduces this intensity. At a fixed jet velocity the higher the equivalence ratio, the higher the amount of fuel diffused and engulfed to the reaction zone, the more delay of the combustion completion and the higher the emission concentrations of the flame. © 2012 Elsevier Inc.

Influence of collective nonideal shielding on fusion reaction in partially ionized classical nonideal plasmas

Science.gov (United States)

Lee, Myoung-Jae; Jung, Young-Dae

2017-04-01

The collective nonideal effects on the nuclear fusion reaction process are investigated in partially ionized classical nonideal hydrogen plasmas. The effective pseudopotential model taking into account the collective and plasma shielding effects is applied to describe the interaction potential in nonideal plasmas. The analytic expressions of the Sommerfeld parameter, the fusion penetration factor, and the cross section for the nuclear fusion reaction in nonideal plasmas are obtained as functions of the nonideality parameter, Debye length, and relative kinetic energy. It is found that the Sommerfeld parameter is suppressed due to the influence of collective nonideal shielding. However, the collective nonideal shielding is found to enhance the fusion penetration factor in partially ionized classical nonideal plasmas. It is also found that the fusion penetration factors in nonideal plasmas represented by the pseudopotential model are always greater than those in ideal plasmas represented by the Debye-Hückel model. In addition, it is shown that the collective nonideal shielding effect on the fusion penetration factor decreases with an increase of the kinetic energy.

Evidence for partial melting of eclogite from the Moldanubian Zone of the Bohemian Massif, Czech Republic

Czech Academy of Sciences Publication Activity Database

Miyazaki, T.; Nakamura, D.; Tamura, A.; Svojtka, Martin; Arai, S.; Hirajima, T.

2016-01-01

Roč. 111, č. 6 (2016), s. 405-419 ISSN 1345-6296 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100131203 Program:Program interní podpory projektů mezinárodní spolupráce AV ČR Institutional support: RVO:67985831 Keywords : partial melting * eclogite * leucocratic pockets * Bohemian Massif * Moldanubian Zone Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.409, year: 2016

Zone separator for multiple zone vessels

Science.gov (United States)

Jones, John B.

1983-02-01

A solids-gas contact vessel, having two vertically disposed distinct reaction zones, includes a dynamic seal passing solids from an upper to a lower zone and maintaining a gas seal against the transfer of the separate treating gases from one zone to the other, and including a stream of sealing fluid at the seal.

Coniferons forests in the thirty kilometer zone of the Chernobyl' NPP

International Nuclear Information System (INIS)

Kozubov, G.M.; Taskaev, A.I.; Zhdanova, N.V.; Kozlov, V.A.; Patov, A.I.; Galkina, E.V.; Kuziv, E.A.

1992-01-01

Four zones of pine forests are distinguished on basis of contamination degree: the lethal zone with complete pine ruin, 'red forest', the sublethal zone with partial pine daying off and mass branch dry up; zone of an average lesion with depression of growth processes and a morphose formation; zone of a weak exposure, where the radiation effect expressed in pine reproductive, sphere changes. It is noted, that the pine reproductive structures have most sensitivity, to the radiation induced ionization. Morphofunctional peculiaryties of the pine reaction to the radiation exposure in the accident region. A hypothesis in proposed. In accordance with the hypothesis the high radiosensitivity phenomenon of conifers is due to their two structural-metabolic peculiarities: by a considerable dimensions of nuclei-chromosomal complex at the high nucleoproteides content and by a lipid metabolism predomination in the all important links of the metabolism. 24 refs.; 3 tabs

Extinction of laminar partially premixed flames

Energy Technology Data Exchange (ETDEWEB)

Aggarwal, Suresh K. [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street, Room 2039, MC-251, Chicago, IL 60607-7022 (United States)

2009-12-15

Flame extinction represents one of the classical phenomena in combustion science. It is important to a variety of combustion systems in transportation and power generation applications. Flame extinguishment studies are also motivated from the consideration of fire safety and suppression. Such studies have generally considered non-premixed and premixed flames, although fires can often originate in a partially premixed mode, i.e., fuel and oxidizer are partially premixed as they are transported to the reaction zone. Several recent investigations have considered this scenario and focused on the extinction of partially premixed flames (PPFs). Such flames have been described as hybrid flames possessing characteristics of both premixed and non-premixed flames. This paper provides a review of studies dealing with the extinction of PPFs, which represent a broad family of flames, including double, triple (tribrachial), and edge flames. Theoretical, numerical and experimental studies dealing with the extinction of such flames in coflow and counterflow configurations are discussed. Since these flames contain both premixed and non-premixed burning zones, a brief review of the dilution-induced extinction of premixed and non-premixed flames is also provided. For the coflow configuration, processes associated with flame liftoff and blowout are described. Since lifted non-premixed jet flames often contain a partially premixed or an edge-flame structure prior to blowout, the review also considers such flames. While the perspective of this review is broad focusing on the fundamental aspects of flame extinction and blowout, results mostly consider flame extinction caused by the addition of a flame suppressant, with relevance to fire suppression on earth and in space environment. With respect to the latter, the effect of gravity on the extinction of PPFs is discussed. Future research needs are identified. (author)

South-Tibetan partially molten batholiths: geophysical characterization and petrological assessment of their origin

Science.gov (United States)

Hetényi, G.; Pistone, M.; Nabelek, P. I.; Baumgartner, L. P.

2017-12-01

Zones of partial melt in the middle crust of Lhasa Block, Southern Tibet, have been geophysically observed as seismically reflective "bright spots" in the past 20 years. These batholiths bear important relevance for geodynamics as they serve as the principal observation at depth supporting channel-flow models in the Himalaya-Tibet orogen. Here we assess the spatial abundance of and partial melt volume fraction within these crustal batholiths, and establish lower and upper estimate bounds using a joint geophysical-petrological approach.Geophysical imaging constrains the abundance of partial melt zones to 5.6 km3 per surface-km2 on average (minimum: 3.1 km3/km2, maximum: 7.6 km3/km2 over the mapped area). Physical properties detected by field geophysics and interpreted by laboratory measurements constrain the amount of partial melt to be between 5 and 26 percent.We evaluate the compatibility of these estimates with petrological modeling based on geotherms, crustal bulk rock compositions and water contents consistent with the Lhasa Block. These simulations determine: (a) the physico-chemical conditions of melt generation at the base of the Tibetan crust and its transport and emplacement in the middle crust; (b) the melt percentage produced at the source, transported and emplaced to form the observed "bright spots". Two main mechanisms are considered: (1) melting induced by fluids produced during mineral dehydration reactions in the underthrusting Indian lower crust; (2) dehydration-melting reactions caused by heating within the Tibetan crust. We find that both mechanisms demonstrate first-order match in explaining the formation of the partially molten "bright spots". Thermal modelling shows that the Lhasa Block batholiths have only small amounts of melt and only for geologically short times (features of the geodynamic evolution. Their transience excludes both long-distance and long-lasting channel flow transport in Tibet.

Alternate partial root-zone irrigation improves fertilizer-N use efficiency in tomatoes

DEFF Research Database (Denmark)

Wang, Yaosheng; Liu, Fulai; Jensen, Lars Stoumann

2013-01-01

The objective of this study was to investigate the comparative effects of alternative partial root-zone irrigation (PRI) and deficit irrigation (DI) on fertilizer-N use efficiency in tomato plants under mineral N and organic N fertilizations. The plants were grown in split-root pots in a climate......-controlled glasshouse and were subjected to PRI and DI treatments during early fruiting stage. When analyzed across the N fertilizer treatments, PRI treatment led to significantly higher N yield, agronomic N use efficiency (ANUE), and apparent N recovery efficiency (ANRE) as compared with the DI treatment, indicating...... significantly higher fertilizer-N use efficiency and soil N availability as well as enhanced plant’s N acquisition ability in the PRI treatment. Analysis across the irrigation treatments showed that the mineral N fertilizer treatment (MinN) significantly increased N yield, ANUE and ANRE relative to the organic...

Performance of RC columns with partial length corrosion

International Nuclear Information System (INIS)

Wang Xiaohui; Liang Fayun

2008-01-01

Experimental and analytical studies on the load capacity of reinforced concrete (RC) columns with partial length corrosion are presented, where only a fraction of the column length was corroded. Twelve simply supported columns were eccentrically loaded. The primary variables were partial length corrosion in tensile or compressive zone and the corrosion level within this length. The failure of the corroded column occurs in the partial length, mainly developed from or located nearby or merged with the longitudinal corrosion cracks. For RC column with large eccentricity, load capacity of the column is mainly influenced by the partial length corrosion in tensile zone; while for RC column with small eccentricity, load capacity of the column greatly decreases due to the partial length corrosion in compressive zone. The destruction of the longitudinally mechanical integrality of the column in the partial length leads to this great reduction of the load capacity of the RC column

From stochastic processes to numerical methods: A new scheme for solving reaction subdiffusion fractional partial differential equations

Energy Technology Data Exchange (ETDEWEB)

Angstmann, C.N.; Donnelly, I.C. [School of Mathematics and Statistics, UNSW Australia, Sydney NSW 2052 (Australia); Henry, B.I., E-mail: B.Henry@unsw.edu.au [School of Mathematics and Statistics, UNSW Australia, Sydney NSW 2052 (Australia); Jacobs, B.A. [School of Computer Science and Applied Mathematics, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050 (South Africa); DST–NRF Centre of Excellence in Mathematical and Statistical Sciences (CoE-MaSS) (South Africa); Langlands, T.A.M. [Department of Mathematics and Computing, University of Southern Queensland, Toowoomba QLD 4350 (Australia); Nichols, J.A. [School of Mathematics and Statistics, UNSW Australia, Sydney NSW 2052 (Australia)

2016-02-15

We have introduced a new explicit numerical method, based on a discrete stochastic process, for solving a class of fractional partial differential equations that model reaction subdiffusion. The scheme is derived from the master equations for the evolution of the probability density of a sum of discrete time random walks. We show that the diffusion limit of the master equations recovers the fractional partial differential equation of interest. This limiting procedure guarantees the consistency of the numerical scheme. The positivity of the solution and stability results are simply obtained, provided that the underlying process is well posed. We also show that the method can be applied to standard reaction–diffusion equations. This work highlights the broader applicability of using discrete stochastic processes to provide numerical schemes for partial differential equations, including fractional partial differential equations.

Spatial distributions of biogeochemical reactions in freshwater-saltwater mixing zones of sandy beach aquifers

Science.gov (United States)

Kim, K. H.; Michael, H. A.; Ullman, W. J.; Cai, W. J.

2017-12-01

Beach aquifers host biogeochemically dynamic mixing zones between fresh and saline groundwaters of contrasting origins, histories, and compositions. Seawater, driven up the beachface by waves and tides, infiltrates into the sand and meets the seaward-discharging fresh groundwater, creating and maintaining a highly reactive intertidal circulation cell well-defined by salinity. Seawater supplies oxygen and reactive carbon to the circulation cell, supporting biogeochemical reactions within the cell that transform and attenuate dissolved nutrient fluxes from terrestrial sources. We investigated the spatial distribution of chemical reaction zones within the intertidal circulation cell at Cape Shores, Lewes, Delaware. Porewater samples were collected from multi-level wells along a beach-perpendicular transect. Samples were analyzed for particulate carbon and reactive solutes, and incubated to obtain rates of oxic respiration and denitrification. High rates of oxic respiration were observed higher on the beach, in the landward freshwater-saline water mixing zone, where dissolved oxygen availability was high. Denitrification was dominant in lower areas of the beach, below the intertidal discharge point. High respiration rates did not correlate with particulate carbon concentrations entrained within porewater, suggesting that dissolved organic carbon or immobile particulate carbon trapped within the sediment can contribute to and alter bulk reactivity. A better understanding of the sources and sinks of carbon within the beach will improve our ability to predict nutrient fluxes to estuaries and oceans, aiding the management of coastal environments and ecosystems.

Partial gamma-ray cross section measurements in 109Ag(n, x n y p gamma) reactions

Energy Technology Data Exchange (ETDEWEB)

Fotiadis, Nikolaos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devlin, Matthew James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Ronald Owen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carroll, James [US Army Research Laboratory, Adelphi, MD (United States)

2015-06-02

We report on absolute partial cross sections for production of discrete γ-rays using ¹⁰⁹Ag(n, xnypγ) reactions with x ≤ 7 and y ≤ 1 in a total of 12 reaction channels. The data were taken using the GEANIE spectrometer comprised of 20 high-purity Ge detectors with 20 BGO escape-suppression shields. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center’s (LANSCE) WNR facility provided neutrons in the energy range from 0.2 to 300 MeV. The time-of- flight technique was used to determine the incident neutron energies. Partial γ-ray cross sections have been measured for a total of 109 transitions and for neutron energies 0.8 MeV< E_n<300 MeV. An estimate of the population of isomers in the (n, n'), (n, 2n) and (n, 3n) channels was made.

Microstructure formation in partially melted zone during gas tungsten arc welding of AZ91 Mg cast alloy

International Nuclear Information System (INIS)

Zhu Tianping; Chen, Zhan W.; Gao Wei

2008-01-01

During gas tungsten arc (GTA) welding of AZ91 Mg cast alloy, constitutional liquid forms locally in the original interdendritic regions in the partially melted zone (PMZ). The PMZ re-solidification behaviour has not been well understood. In this study, the gradual change of the re-solidification microstructure within PMZ from base metal side to weld metal side was characterised. High cooling rate experiments using Gleeble thermal simulator were also conducted to understand the morphological change of the α-Mg/β-Mg 17 Al 12 phase interface formed during re-solidification after partial melting. It was found that the original partially divorced eutectic structure has become a more regular eutectic phase in most of the PMZ, although close to the fusion boundary the re-solidified eutectic is again a divorced one. Proceeding the eutectic re-solidification, if the degree of partial melting is sufficiently high, α-Mg re-solidified with a cellular growth, resulting in a serrated interface between α-Mg and α-Mg/β-Mg 17 Al 12 in the weld sample and between α-Mg and β-Mg 17 Al 12 (fully divorced eutectic) in Gleeble samples. The morphological changes affected by the peak temperature and cooling rate are also explained

New approach to analyzing and evaluating cross sections for partial photoneutron reactions

International Nuclear Information System (INIS)

Varlamov, V. V.; Ishkhanov, B. S.; Orlin, V. N.

2012-01-01

The presence of substantial systematic discrepancies between the results of different experiments devoted to determining cross sections for partial photoneutron reactions—first of all, (γ, n), (γ, 2n), and (γ, 3n) reactions—is a strong motivation for studying the reliability and authenticity of these data and for developing methods for taking into account and removing the discrepancies in question. In order to solve the first problem, we introduce objective absolute criteria involving transitional photoneutron-multiplicity functions F 1 , F 2 , F 3 , …; by definition, their values cannot exceed 1.0, 0.5, 0.33, …, respectively. With the aim of solving the second problem, we propose a new experimental-theoretical approach. In this approach, reaction cross sections are evaluated by simultaneously employing experimental data on the cross section for the total photoneutron yield, σ expt (γ, xn) = σ expt (γ, n) + 2σ expt (γ, 2n) + 3σ expt (γ, 3n) + …, which are free from drawbacks plaguing experimental methods for sorting neutrons in multiplicity, and the results obtained by calculating the functions F theor 1 , F theor 2 , F theor 3 , … on the basis of the modern model of photonuclear reactions. The reliability and authenticity of data on the cross sections for (γ, n), (γ, 2n), and (γ, 3n) partial reactions—σ eval (γ, in) = F i theor σ expt (γ, xn)—were evaluated for the 90 Zr, 115 In, 112,114,116,117,118,119,120,122,124 Sn, 159 Tb, and 197 Au nuclei.

Dehydration-driven topotaxy in subduction zones

Science.gov (United States)

Padrón-Navarta, José Alberto; Tommasi, Andréa; Garrido, Carlos J.

2014-05-01

Mineral replacement reactions play a fundamental role in the chemistry and the strength of the lithosphere. When externally or internally derived fluids are present, interface-coupled dissolution-precipitation is the driving mechanism for such reactions [1]. One of the microstructural features of this process is a 3D arrangement of crystallographic axes across internal interfaces (topotaxy) between reactant and product phases. Dehydration reactions are a special case of mineral replacement reaction that generates a transient fluid-filled porosity. Among others, the dehydration serpentinite is of special relevance in subduction zones because of the amount of fluids involved (potentially up to 13 wt.%). Two topotatic relationships between olivine and antigorite (the serpentine mineral stable at high temperature and pressure) have been reported in partially hydrated mantle wedge xenoliths [2]. Therefore, if precursor antigorite serpentine has a strong crystallographic preferred orientation (CPO) its dehydration might result in prograde peridotite with a strong inherited CPO. However for predicting the importance of topotactic reactions for seismic anisotropy of subduction zones we also need to consider the crystallization orthopyroxene + chlorite in the prograde reaction and, more importantly, the fact that this dehydration reaction produces a transient porosity of ca. 20 % vol. that results in local fluctuations of strain during compaction and fluid migration. We address this issue by a microstructural comparison between the CPO developed in olivine, orthopyroxene and chlorite during high-pressure antigorite dehydration in piston cylinder experiments (at 750ºC and 20 kbar and 1000ºC and 30 kbar, 168 h) and that recorded in natural samples (Cerro del Almirez, Betic Cordillera, Spain). Experimentally developed CPOs are strong. Prograde minerals show a significant inheritance of the former antigorite foliation. Topotactic relations are dominated by (001)atg//(100)ol

Explicit integration of extremely stiff reaction networks: partial equilibrium methods

International Nuclear Information System (INIS)

Guidry, M W; Hix, W R; Billings, J J

2013-01-01

In two preceding papers (Guidry et al 2013 Comput. Sci. Disc. 6 015001 and Guidry and Harris 2013 Comput. Sci. Disc. 6 015002), we have shown that when reaction networks are well removed from equilibrium, explicit asymptotic and quasi-steady-state approximations can give algebraically stabilized integration schemes that rival standard implicit methods in accuracy and speed for extremely stiff systems. However, we also showed that these explicit methods remain accurate but are no longer competitive in speed as the network approaches equilibrium. In this paper, we analyze this failure and show that it is associated with the presence of fast equilibration timescales that neither asymptotic nor quasi-steady-state approximations are able to remove efficiently from the numerical integration. Based on this understanding, we develop a partial equilibrium method to deal effectively with the approach to equilibrium and show that explicit asymptotic methods, combined with the new partial equilibrium methods, give an integration scheme that can plausibly deal with the stiffest networks, even in the approach to equilibrium, with accuracy and speed competitive with that of implicit methods. Thus we demonstrate that such explicit methods may offer alternatives to implicit integration of even extremely stiff systems and that these methods may permit integration of much larger networks than have been possible before in a number of fields. (paper)

Time variation in the reaction-zone structure of two-phase spray detonations.

Science.gov (United States)

Pierce, T. H.; Nicholls, J. A.

1973-01-01

A detailed theoretical analysis of the time-varying detonation structure in a monodisperse spray is presented. The theory identifies experimentally observed reaction-zone overpressures as deriving from blast waves formed therein by the explosive ignition of the spray droplets, and follows in time the motion, change in strength, and interactions of these blast waves with one another, and with the leading shock. The results are compared with experimental data by modeling the motion of a finite-size circular pressure transducer through the theoretical data field in an x-t space.

Study of flow profile distortions and efficiency in counter pressure moderated partial filling micellar electrokinetic chromatography in relation to the relative buffer zone lengths.

Science.gov (United States)

Michalke, Daniela; Welsch, Thomas

2002-06-25

The influence of the relative buffer zone lengths on the efficiency was investigated in partial filling micellar electrokinetic chromatography using sodium dodecyl sulfate as separation additive. Varying relative zone lengths were obtained by applying identical initial separation zone lengths but different total lengths of the capillaries. Plate numbers of a homologous series of omega-phenylalcohols were measured to indicate the effect of both a changing relative zone length during the run and a counter pressure applied on the cathodic buffer reservoir. The magnitude and the course of these plate numbers are discussed on the basis of models for flow profile superposition and flow profile deformation which are caused by an intersegmental pressure arising at the boundary between the two buffer zones with different electroosmotic flow velocities. Calculation of the intersegmental pressure and of the resulting laminar flow components in the buffer zones on the basis of some equations for electroosmotic and hydrodynamic flow supported the interpretation that a long background buffer zone should be avoided

Simulation assessment of continuous simulating moving bed chromatography process with partial feed and new strategy with partial feed

Directory of Open Access Journals (Sweden)

H. Khan

2009-09-01

Full Text Available Partial Feed simulating moving bed (SMB has proved to be more efficient in binary separation performance (purity, recovery, productivity because of its two additional degrees of freedom, namely feed length and feed time, as compared to classical SMB process. The binary separation of dextran T6 and fructose with linear isotherm is modeled with Aspen Chromatography simulator in a four zone SMB with one column per zone for both normal-feed and Partial Feed. Increase in number of feed length and feed time in the cycle plays a very important role in the separation performance with Partial Feed. In addition, the effect of mode of operation (early or late introduction of increase in number of feed length in the cycle on product purity and recovery is also investigated. Furthermore, the binary separation system is designed with the safety margin method and the optimum operating parameters for simulation are calculated with triangle theory. Finally, a new strategy with Partial Feed is developed, showing improved separation performance relative to the basic four-zone SMB with regard to extract stream purity and recovery. The results of the proposed study can served as a useful summary of Partial Feed operation.

Turbulent piloted partially-premixed flames with varying levels of O2/N2: stability limits and PDF calculations

Science.gov (United States)

Juddoo, Mrinal; Masri, Assaad R.; Pope, Stephen B.

2011-12-01

This paper reports measured stability limits and PDF calculations of piloted, turbulent flames of compressed natural gas (CNG) partially-premixed with either pure oxygen, or with varying levels of O2/N2. Stability limits are presented for flames of CNG fuel premixed with up to 20% oxygen as well as CNG-O2-N2 fuel where the O2 content is varied from 8 to 22% by volume. Calculations are presented for (i) Sydney flame B [Masri et al. 1988] which uses pure CNG as well as flames B15 to B25 where the CNG is partially-premixed with 15-25% oxygen by volume, respectively and (ii) Sandia methane-air (1:3 by volume) flame E [Barlow et al. 2005] as well as new flames E15 and E25 that are partially-premixed with 'reconstituted air' where the O2 content in nitrogen is 15 and 25% by volume, respectively. The calculations solve a transported PDF of composition using a particle-based Monte Carlo method and employ the EMST mixing model as well as detailed chemical kinetics. The addition of oxygen to the fuel increases stability, shortens the flames, broadens the reaction zone, and shifts the stoichiometric mixture fraction towards the inner side of the jet. It is found that for pure CNG flames where the reaction zone is narrow (∼0.1 in mixture fraction space), the PDF calculations fail to reproduce the correct level of local extinction on approach to blow-off. A broadening in the reaction zone up to about 0.25 in mixture fraction space is needed for the PDF/EMST approach to be able to capture these finite-rate chemistry effects. It is also found that for the same level of partial premixing, increasing the O2/N2 ratio increases the maximum levels of CO and NO but shifts the peak to richer mixture fractions. Over the range of oxygenation investigated here, stability limits have shown to improve almost linearly with increasing oxygen levels in the fuel and with increasing the contribution of release rate from the pilot.

Investigation into boron reaction with titanium at extreme temperature gradients

International Nuclear Information System (INIS)

Korchagin, M.A.; Gusenko, S.N.; Aleksandrov, V.V.; Neronov, V.A.

1981-01-01

The mechanism of self-propagation high-temperature synthesis of titanium boride is studied using the translucent electron microscopy. Titanium interaction with boron film (approximately 1000 A thick) starts with the metal partial melting. A twozone layer of the reaction products, separating the reagents, is formed. In the zone adjacent to B, Ti 3 B 4 and fusible liquid phases are present. The second zone consists of TiB. The subsequent interaction is realized by Means of the dissolving and absorption by titanium of the layer of products during its continuous increase in boron. TiB 2 formation takes place at subsequent stages of interaction inside Ti liquid particles during their saturation by boron from the products absorbed [ru

Oklo natural reactor. Study of uranium and rare earths migration on a core drilled through a reaction zone. Application to determination of the date of the nuclear reaction by measurement of fission products

International Nuclear Information System (INIS)

Ruffenach, J.C.

1977-01-01

Isotopic and chemical analysis of uranium and five rare earths: neodymium, samarium, europium, gadolinium and dysprosium were effected on fourteen samples taken in the same core drilled through a reaction zone of the Oklo uranium deposit. This study points out the general stability of uranium and fission rare earths; spatial distributions of these elements are quite analogous. Migrations have affected about 5% only of fission neodymium in the core of the reaction zone; corresponding values for samarium and gadolinium are slightly higher. These migration phenomena have carried rare earths to no more than 80 cm out of the core. By study of the europium it is shown that nuclear reactions have stayed in the ground since the time of reactions. On the other hand it is shown by analysis of the dysprosium that rare earths have not undergone an important movement. This study allow also the datation of nuclear reactions from the measurement of the quantity of fission neodymium produced. A value of 1.98x10 9 years is obtained slightly higher than the value obtained by geochronology [fr

Optimal Control Method of Parabolic Partial Differential Equations and Its Application to Heat Transfer Model in Continuous Cast Secondary Cooling Zone

Directory of Open Access Journals (Sweden)

Yuan Wang

2015-01-01

Full Text Available Our work is devoted to a class of optimal control problems of parabolic partial differential equations. Because of the partial differential equations constraints, it is rather difficult to solve the optimization problem. The gradient of the cost function can be found by the adjoint problem approach. Based on the adjoint problem approach, the gradient of cost function is proved to be Lipschitz continuous. An improved conjugate method is applied to solve this optimization problem and this algorithm is proved to be convergent. This method is applied to set-point values in continuous cast secondary cooling zone. Based on the real data in a plant, the simulation experiments show that the method can ensure the steel billet quality. From these experiment results, it is concluded that the improved conjugate gradient algorithm is convergent and the method is effective in optimal control problem of partial differential equations.

Effect of Regulated Deficit Irrigation (RDI) and Partial Root zone Drying (PRD) on Quantitative and Qualitative Traits of Strawberry

OpenAIRE

A. Shahnazari; M. Rezaiyan

2016-01-01

Introduction: Deficit irrigation (DI) is a suitable solution to gain acceptable and economic performance by using minimum amount of water. The partial root zone drying (PRD) method introduced in Australia for the first time and its goal was controlling the vine’s excessive growth. This goal gained by alternative drying the rootzone. Basically the theory of PRD method, is expanding the plant’s roots by applying alternative stress on different sides of the roots. So the plants with PRD irrigati...

Evaluation Yield of Sunflower (Farrokh cultivar under Effects of Conventional Deficit Irrigation and Partial Root Zone Drying

Directory of Open Access Journals (Sweden)

A. Rezaei Estakhroeih

2015-06-01

Full Text Available Water shortage is the most important factors on crop production in the world. Several methods of deficit irrigation are solutions for reduction of irrigation water. To understand the effects of conventional deficit irrigation and partial root zone drying treatments on yield, yield components and water use efficiency of sunflower (Farrokh cultivar, one study was carried out. The research was conducted on Shahid Bahonar University of Kerman in the spring of 2011. A factorial experiment in a randomized complete block design with one control (full irrigation and 18 deficit irrigation treatments in three replications was considered. Deficit irrigation treatments were: conventional deficit irrigation (irrigation with %80, %60 and %40 ETP and partial root zone drying (irrigation with %80, %60 and %40 ETP. Every deficit irrigation treatment was conducted in three growth stage of sunflower (all periods of growth, vegetative growth stage and reproductive growth stage.The results showed that the conventional deficit irrigation treatments (irrigation with 80% ETP in vegetative growth had the highest plant height, leaf area, leaf area index and head diameter. Also, the maximum biological yield equal to49054, maximum grain yield is equal to 9934/3 and maximum oil yield is equal to 2441/2 kg per hectare in the conventional deficit irrigation treatments (irrigation with 80% ETP in vegetative growth occurred.The highest water use efficiency for grain yield is equal to 1/46,forbiological yield equal to7/21 and for dry forage yield is equal 5/7 kilograms per cubic meter of water. According to results,conventional deficit irrigation (irrigation with %80, %60 and %40 ETP is recommended on based.

A dynamical theory of incomplete fusion reactions: The breakup-fusion reaction approach

International Nuclear Information System (INIS)

Udagawa, T.

1984-01-01

A dynamical theory of partial fusion reactions is presented, which may fill the gap between direct and compound nuclear reaction theories. With the new theory one can calculate partial fusion taking place in three-body (and many more) channels reached via direct reactions, e.g., breakup and knockout reactions. The authors present first the results for the cross section for such reactions, taking as an example breakup followed by fusion. They then discuss a physical picture which emerges from their theory, namely that the partial fusion reactions, particularly of the massive-transfer type, take place in a so-called deep peripheral region. It is also shown that the deep peripheral character of such processes diminishes as the mass of the fused system decreases, so that the reactions essentially evolve to the usual peripheral character. Finally, comparisons are made of results of numerical calculations with experimental data, taking as an example the /sup 159/Tb(/sup 14/N,α) reaction with E/sub lab/ = 95 MeV

First results of total and partial cross-section measurements of the 107Ag(p,γ)108Cd reaction

Science.gov (United States)

Heim, Felix; Mayer, Jan; Scholz, Philipp; Spieker, Mark; Zilges, Andreas

2018-01-01

The γ process is assumed to play an important role in the nucleosynthesis of the majority of the p nuclei. Since the network of the γ process includes so many different reactions and - mainly unstable - nuclei, cross-section values are predominantly calculated in the scope of the Hauser-Feshbach statistical model. The values heavily depend on the nuclear-physics input parameters. The results of total and partial cross-section measurements are used to improve the accuracy of the theoretical calculations. In order to extend the experimental database, the 107Ag(p,γ)108Cd reaction was studied via the in-beam method at the high-efficiency HPGe γ-ray spectrometer HORUS at the University of Cologne. Proton beams with energies between 3.5 MeV and 5.0 MeV were provided by the 10 MV FN-Tandem accelerator leading to the determination of four new total cross-section values. After slight adjustments of the nuclear level density and γ-ray strength function an excellent agreement between theoretical calculations and experimentally deduced values for both total and partial cross sections has been obtained.

Dynamics and mitigation of six pesticides in a "Wet" forest buffer zone.

Science.gov (United States)

Passeport, Elodie; Richard, Benjamin; Chaumont, Cédric; Margoum, Christelle; Liger, Lucie; Gril, Jean-Joël; Tournebize, Julien

2014-04-01

Pesticide pollution is one of the main current threats on water quality. This paper presents the potential and functioning principles of a "Wet" forest buffer zone for reducing concentrations and loads of glyphosate, isoproturon, metazachlor, azoxystrobin, epoxiconazole, and cyproconazole. A tracer injection experiment was conducted in the field in a forest buffer zone at Bray (France). A fine time-scale sampling enabled to illustrate that interactions between pesticides and forest buffer substrates (soil and organic-rich litter layer), had a retarding effect on molecule transfer. Low concentrations were observed for all pesticides at the forest buffer outlet thus demonstrating the efficiency of "Wet" forest buffer zone for pesticide dissipation. Pesticide masses injected in the forest buffer inlet directly determined concentration peaks observed at the outlet. Rapid and partially reversible adsorption was likely the major process affecting pesticide transfer for short retention times (a few hours to a few days). Remobilization of metazachlor, isoproturon, desmethylisoproturon, and AMPA was observed when non-contaminated water flows passed through the forest buffer. Our data suggest that pesticide sorption properties alone could not explain the complex reaction mechanisms that affected pesticide transfer in the forest buffer. Nevertheless, the thick layer of organic matter litter on the top of the forest soil was a key parameter, which enhanced partially reversible sorption of pesticide, thus retarded their transfer, decreased concentration peaks, and likely increased degradation of the pesticides. Consequently, to limit pesticide pollution transported by surface water, the use of already existing forest areas as buffer zones should be equally considered as the most commonly implemented grass buffer strips.

Lecithin-cholesterol acyltransferase (LCAT) catalyzes transacylation of intact cholesteryl esters. Evidence for the partial reversal of the forward LCAT reaction

International Nuclear Information System (INIS)

Sorci-Thomas, M.; Babiak, J.; Rudel, L.L.

1990-01-01

Lecithin-cholesterol acyltransferase (LCAT) catalyzes the intravascular synthesis of lipoprotein cholesteryl esters by converting cholesterol and lecithin to cholesteryl ester and lysolecithin. LCAT is unique in that it catalyzes sequential reactions within a single polypeptide sequence. In this report we find that LCAT mediates a partial reverse reaction, the transacylation of lipoprotein cholesteryl oleate, in whole plasma and in a purified, reconstituted system. As a result of the reverse transacylation reaction, a linear accumulation of [3H]cholesterol occurred during incubations of plasma containing high density lipoprotein labeled with [3H]cholesteryl oleate. When high density lipoprotein labeled with cholesteryl [14C]oleate was also included in the incubation the labeled fatty acyl moiety remained in the cholesteryl [14C]oleate pool showing that the formation of labeled cholesterol did not result from hydrolysis of the doubly labeled cholesteryl esters. The rate of release of [3H]cholesterol was only about 10% of the forward rate of esterification of cholesterol using partially purified human LCAT and was approximately 7% in whole monkey plasma. Therefore, net production of cholesterol via the reverse LCAT reaction would not occur. [3H]Cholesterol production from [3H]cholesteryl oleate was almost completely inhibited by a final concentration of 1.4 mM 5,5'-dithiobis(nitrobenzoic acid) during incubation with either purified LCAT or whole plasma. Addition of excess lysolecithin to the incubation system did not result in the formation of [14C]oleate-labeled lecithin, showing that the reverse reaction found here for LCAT was limited to the last step of the reaction. To explain these results we hypothesize that LCAT forms a [14C]oleate enzyme thioester intermediate after its attack on the cholesteryl oleate molecule

Growth and proteomic analysis of tomato fruit under partial root-zone drying.

Science.gov (United States)

Marjanović, Milena; Stikić, Radmila; Vucelić-Radović, Biljana; Savić, Sladjana; Jovanović, Zorica; Bertin, Nadia; Faurobert, Mireille

2012-06-01

The effects of partial root-zone drying (PRD) on tomato fruit growth and proteome in the pericarp of cultivar Ailsa Craig were investigated. The PRD treatment was 70% of water applied to fully irrigated (FI) plants. PRD reduced the fruit number and slightly increased the fruit diameter, whereas the total fruit fresh weight (FW) and dry weight (DW) per plant did not change. Although the growth rate was higher in FI than in PRD fruits, the longer period of cell expansion resulted in bigger PRD fruits. Proteins were extracted from pericarp tissue at two fruit growth stages (15 and 30 days post-anthesis [dpa]), and submitted to proteomic analysis including two-dimensional gel electrophoresis and mass spectrometry for identification. Proteins related to carbon and amino acid metabolism indicated that slower metabolic flux in PRD fruits may be the cause of a slower growth rate compared to FI fruits. The increase in expression of the proteins related to cell wall, energy, and stress defense could allow PRD fruits to increase the duration of fruit growth compared to FI fruits. Upregulation of some of the antioxidative enzymes during the cell expansion phase of PRD fruits appears to be related to their role in protecting fruits against the mild stress induced by PRD.

Evaluation of partially premixed turbulent flame stability from mixture fraction statistics in a slot burner

KAUST Repository

Kruse, Stephan

2018-04-11

Partially premixed combustion is characterized by mixture fraction inhomogeneity upstream of the reaction zone and occurs in many applied combustion systems. The temporal and spatial fluctuations of the mixture fraction have tremendous impact on the combustion characteristics, emission formation, and flame stability. In this study, turbulent partially premixed flames are experimentally studied in a slot burner configuration. The local temperature and gas composition is determined by means of one-dimensional, simultaneous detection of Rayleigh and Raman scattering. The statistics of the mixture fraction are utilized to characterize the impact of the Reynolds number, the global equivalence ratio, the progress of mixing within the flame, as well as the mixing length on the mixing field. Furthermore, these effects are evaluated by means of a regime diagram for partially premixed flames. In this study, it is shown that the increase of the mixing length results in a significantly more stable flame. The impact of the Reynolds number on flame stability is found to be minor.

Evaluation of partially premixed turbulent flame stability from mixture fraction statistics in a slot burner

KAUST Repository

Kruse, Stephan; Mansour, Mohy S.; Elbaz, Ayman M.; Varea, Emilien; Grü nefeld, Gerd; Beeckmann, Joachim; Pitsch, Heinz

2018-01-01

Partially premixed combustion is characterized by mixture fraction inhomogeneity upstream of the reaction zone and occurs in many applied combustion systems. The temporal and spatial fluctuations of the mixture fraction have tremendous impact on the combustion characteristics, emission formation, and flame stability. In this study, turbulent partially premixed flames are experimentally studied in a slot burner configuration. The local temperature and gas composition is determined by means of one-dimensional, simultaneous detection of Rayleigh and Raman scattering. The statistics of the mixture fraction are utilized to characterize the impact of the Reynolds number, the global equivalence ratio, the progress of mixing within the flame, as well as the mixing length on the mixing field. Furthermore, these effects are evaluated by means of a regime diagram for partially premixed flames. In this study, it is shown that the increase of the mixing length results in a significantly more stable flame. The impact of the Reynolds number on flame stability is found to be minor.

Extent of reaction in open systems with multiple heterogeneous reactions

Science.gov (United States)

Friedly, John C.

1991-01-01

The familiar batch concept of extent of reaction is reexamined for systems of reactions occurring in open systems. Because species concentrations change as a result of transport processes as well as reactions in open systems, the extent of reaction has been less useful in practice in these applications. It is shown that by defining the extent of the equivalent batch reaction and a second contribution to the extent of reaction due to the transport processes, it is possible to treat the description of the dynamics of flow through porous media accompanied by many chemical reactions in a uniform, concise manner. This approach tends to isolate the reaction terms among themselves and away from the model partial differential equations, thereby enabling treatment of large problems involving both equilibrium and kinetically controlled reactions. Implications on the number of coupled partial differential equations necessary to be solved and on numerical algorithms for solving such problems are discussed. Examples provided illustrate the theory applied to solute transport in groundwater flow.

Reactive transport in a partially molten system with binary solid solution

Science.gov (United States)

Jordan, J.; Hesse, M. A.

2017-12-01

Melt extraction from the Earth's mantle through high-porosity channels is required to explain the composition of the oceanic crust. Feedbacks from reactive melt transport are thought to localize melt into a network of high-porosity channels. Recent studies invoke lithological heterogeneities in the Earth's mantle to seed the localization of partial melts. Therefore, it is necessary to understand the reaction fronts that form as melt flows across the lithological interface of a heterogeneity and the background mantle. Simplified melting models of such systems aide in the interpretation and formulation of larger scale mantle models. Motivated by the aforementioned facts, we present a chromatographic analysis of reactive melt transport across lithological boundaries, using theory for hyperbolic conservation laws. This is an extension of well-known linear trace element chromatography to the coupling of major elements and energy transport. Our analysis allows the prediction of the feedbacks that arise in reactive melt transport due to melting, freezing, dissolution and precipitation for frontal reactions. This study considers the simplified case of a rigid, partially molten porous medium with binary solid solution. As melt traverses a lithological contact-modeled as a Riemann problem-a rich set of features arise, including a reacted zone between an advancing reaction front and partial chemical preservation of the initial contact. Reactive instabilities observed in this study originate at the lithological interface rather than along a chemical gradient as in most studies of mantle dynamics. We present a regime diagram that predicts where reaction fronts become unstable, thereby allowing melt localization into high-porosity channels through reactive instabilities. After constructing the regime diagram, we test the one-dimensional hyperbolic theory against two-dimensional numerical experiments. The one-dimensional hyperbolic theory is sufficient for predicting the

Liftoff characteristics of partially premixed flames under normal and microgravity conditions

Energy Technology Data Exchange (ETDEWEB)

Lock, Andrew J.; Briones, Alejandro M.; Aggarwal, Suresh K. [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Qin, Xiao [Department of Mechanical & amp; Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Puri, Ishwar K. [Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Hegde, Uday [National Center for Microgravity Research, Cleveland, OH 44135 (United States)

2005-11-01

An experimental and computational investigation on the liftoff characteristics of laminar partially premixed flames (PPFs) under normal (1-g) and microgravity ({mu}-g) conditions is presented. Lifted methane-air PPFs were established in axisymmetric coflowing jets using nitrogen dilution and various levels of partial premixing. The {mu}-g experiments were conducted in the 2.2-s drop tower at the NASA Glenn Research Center. A time-accurate, implicit algorithm that uses a detailed description of the chemistry and includes radiation effects is used for the simulations. The predictions are validated through a comparison of the flame reaction zone topologies, liftoff heights, lengths, and oscillation frequencies. The effects of equivalence ratio, gravity, jet velocity, and radiation on flame topology, liftoff height, flame length, base structure, and oscillation frequency are characterized. Both the simulations and measurements indicate that under identical conditions, a lifted {mu}-g PPF is stabilized closer to the burner compared with the 1-g flame, and that the liftoff heights of both 1-g and {mu}-g flames decrease with increasing equivalence ratio and approach their respective nonpremixed flame limits. The liftoff height also increases as the jet velocity is increased. In addition, the flame base structure transitions from a triple- to a double-flame structure as the flame liftoff height decreases. A modified flame index is developed to distinguish between the rich premixed, lean premixed, and nonpremixed reaction zones near the flame base. The 1-g lifted flames exhibit well-organized oscillations due to buoyancy-induced instability, while the corresponding {mu}-g flames exhibit steady-state behavior. The effect of thermal radiation is to slightly decrease the liftoff heights of both 1-g and {mu}-g flames under coflow conditions.

On the Green's function of the partially diffusion-controlled reversible ABCD reaction for radiation chemistry codes

Energy Technology Data Exchange (ETDEWEB)

Plante, Ianik, E-mail: ianik.plante-1@nasa.gov [Wyle Science, Technology & Engineering, 1290 Hercules, Houston, TX 77058 (United States); Devroye, Luc, E-mail: lucdevroye@gmail.com [School of Computer Science, McGill University, 3480 University Street, Montreal H3A 0E9 (Canada)

2015-09-15

Several computer codes simulating chemical reactions in particles systems are based on the Green's functions of the diffusion equation (GFDE). Indeed, many types of chemical systems have been simulated using the exact GFDE, which has also become the gold standard for validating other theoretical models. In this work, a simulation algorithm is presented to sample the interparticle distance for partially diffusion-controlled reversible ABCD reaction. This algorithm is considered exact for 2-particles systems, is faster than conventional look-up tables and uses only a few kilobytes of memory. The simulation results obtained with this method are compared with those obtained with the independent reaction times (IRT) method. This work is part of our effort in developing models to understand the role of chemical reactions in the radiation effects on cells and tissues and may eventually be included in event-based models of space radiation risks. However, as many reactions are of this type in biological systems, this algorithm might play a pivotal role in future simulation programs not only in radiation chemistry, but also in the simulation of biochemical networks in time and space as well.

On the Green's function of the partially diffusion-controlled reversible ABCD reaction for radiation chemistry codes

International Nuclear Information System (INIS)

Plante, Ianik; Devroye, Luc

2015-01-01

Several computer codes simulating chemical reactions in particles systems are based on the Green's functions of the diffusion equation (GFDE). Indeed, many types of chemical systems have been simulated using the exact GFDE, which has also become the gold standard for validating other theoretical models. In this work, a simulation algorithm is presented to sample the interparticle distance for partially diffusion-controlled reversible ABCD reaction. This algorithm is considered exact for 2-particles systems, is faster than conventional look-up tables and uses only a few kilobytes of memory. The simulation results obtained with this method are compared with those obtained with the independent reaction times (IRT) method. This work is part of our effort in developing models to understand the role of chemical reactions in the radiation effects on cells and tissues and may eventually be included in event-based models of space radiation risks. However, as many reactions are of this type in biological systems, this algorithm might play a pivotal role in future simulation programs not only in radiation chemistry, but also in the simulation of biochemical networks in time and space as well

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multi-zone Reaction Kinetics: Model Derivation and Validation

Science.gov (United States)

Rout, Bapin Kumar; Brooks, Geoff; Rhamdhani, M. Akbar; Li, Zushu; Schrama, Frank N. H.; Sun, Jianjun

2018-04-01

A multi-zone kinetic model coupled with a dynamic slag generation model was developed for the simulation of hot metal and slag composition during the basic oxygen furnace (BOF) operation. The three reaction zones (i) jet impact zone, (ii) slag-bulk metal zone, (iii) slag-metal-gas emulsion zone were considered for the calculation of overall refining kinetics. In the rate equations, the transient rate parameters were mathematically described as a function of process variables. A micro and macroscopic rate calculation methodology (micro-kinetics and macro-kinetics) were developed to estimate the total refining contributed by the recirculating metal droplets through the slag-metal emulsion zone. The micro-kinetics involves developing the rate equation for individual droplets in the emulsion. The mathematical models for the size distribution of initial droplets, kinetics of simultaneous refining of elements, the residence time in the emulsion, and dynamic interfacial area change were established in the micro-kinetic model. In the macro-kinetics calculation, a droplet generation model was employed and the total amount of refining by emulsion was calculated by summing the refining from the entire population of returning droplets. A dynamic FetO generation model based on oxygen mass balance was developed and coupled with the multi-zone kinetic model. The effect of post-combustion on the evolution of slag and metal composition was investigated. The model was applied to a 200-ton top blowing converter and the simulated value of metal and slag was found to be in good agreement with the measured data. The post-combustion ratio was found to be an important factor in controlling FetO content in the slag and the kinetics of Mn and P in a BOF process.

Response of partially premixed flames to acoustic velocity and equivalence ratio perturbations

Energy Technology Data Exchange (ETDEWEB)

Kim, K.T.; Lee, J.G.; Quay, B.D.; Santavicca, D.A. [Center for Advanced Power Generation, Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA (United States)

2010-09-15

This article describes an experimental investigation of the forced response of a swirl-stabilized partially premixed flame when it is subjected to acoustic velocity and equivalence ratio fluctuations. The flame's response is analyzed using phase-resolved CH{sup *} chemiluminescence images and flame transfer function (FTF) measurements, and compared with the response of a perfectly premixed flame under acoustic perturbations. The nonlinear response of the partially premixed flame is manifested by a partial extinction of the reaction zone, leading to rapid reduction of flame surface area. This nonlinearity, however, is observed only when the phase difference between the acoustic velocity and the equivalence ratio at the combustor inlet is close to zero. The condition, {delta}{phi}{sub {phi}}'-V'{approx}0 , indicates that reactant mixtures with high equivalence ratio impinge on the flame front with high velocity, inducing large fluctuations of the rate of heat release. It is found that the phase difference between the acoustic velocity and equivalence ratio nonuniformities is a key parameter governing the linear/nonlinear response of a partially premixed flame, and it is a function of modulation frequency, inlet velocity, fuel injection location, and fuel injector impedance. The results presented in this article will provide insight into the response of a partially premixed flame, which has not been well explored to date. (author)

Comparative effects of partial root-zone irrigation and deficit irrigation on phosphorus uptake in tomato plants

DEFF Research Database (Denmark)

Wang, Yaosheng; Liu, Fulai; Jensen, Christian Richardt

2012-01-01

The comparative effects of partial root-zone irrigation (PRI) and deficit irrigation (DI) on phosphorus (P) uptake in tomato (Lycopersicon esculentum Mill.) plants were investigated in a split-root pot experiment. The results showed that PRI treatment improved water-use efficiency (WUE) compared...... to the DI treatment. PRI-treated plants accumulated significantly higher amounts of P in their shoots than DI plants under organic maize straw N fertilisation, whereas similar levels of shoot P accumulation were observed under mineral N fertilisation. Thus, the form of N fertiliser, and thereby...... the different plant N status, affected the accumulation of P in shoots, as reflected by a higher plant N:P ratio following mineral N fertilisation than after organic N fertilisation. Compared to the DI treatment, PRI significantly increased both the physiological and agronomic efficiencies of P-use under...

49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

Science.gov (United States)

2010-10-01

...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre... 49 Transportation 4 2010-10-01 2010-10-01 false How does this rule affect Pre-Rule Quiet Zones and...

Partial gigantism

Directory of Open Access Journals (Sweden)

М.М. Karimova

2017-05-01

Full Text Available A girl with partial gigantism (the increased I and II fingers of the left foot is being examined. This condition is a rare and unresolved problem, as the definite reason of its development is not determined. Wait-and-see strategy is recommended, as well as correcting operations after closing of growth zones, and forming of data pool for generalization and development of schemes of drug and radial therapeutic methods.

Cathodic over-potential and hydrogen partial pressure coupling in hydrogen evolution reaction of marine steel under hydrostatic pressure

International Nuclear Information System (INIS)

Xiong, X.L.; Zhou, Q.J.; Li, J.X.; Volinsky, Alex A.; Su, Y.J.

2017-01-01

Highlights: •Hydrostatic pressure increases the Volmer and the Heyrovsky reactions rates. •Hydrostatic pressure decreases the Tafel reaction rate. •Hydrogen adsorption conditions change with pressure under −1.2 and −1.3 V SSE . •Under −1.2 and −1.3 V SSE , the Heyrovsky reaction dominates the hydrogen recombination. •Under −1.0 and −1.1 V SSE , the Tafel reaction dominates the hydrogen recombination. -- Abstract: A new electrochemical impedance spectroscopy (EIS) model, which considers both the Tafel recombination and the Heyrovsky reaction under permeable boundary conditions, was developed to characterize the kinetic parameters of the hydrogen evolution reaction (HER) under hydrostatic pressure. The effect of the hydrostatic pressure on the kinetic parameters of the HER and the permeation of A514 steel in alkaline solution were measured using potentiodynamic polarization, the Devanathan cell hydrogen permeation, and EIS. The hydrostatic pressure accelerates the Volmer reaction and inhibits the Tafel recombination, which increases the number of adsorbed hydrogen atoms. On the other hand, the pressure accelerates the Heyrovsky reaction, which decreases the amount of adsorbed hydrogen atoms. At 10 to 40 MPa hydrostatic pressure within the −1.0 to −1.1 V SSE cathodic potential region, the HER is controlled by hydrogen partial pressure, and hydrogen adsorption is the Langmuir type. Within the −1.2 to −1.3 V SSE cathodic potential region, the HER is controlled by the potential, and hydrogen adsorption gradually transfers from the Langmuir type to the Temkin type with increasing hydrostatic pressure.

Reaction softening by dissolution–precipitation creep in a retrograde greenschist facies ductile shear zone, New Hampshire, USA

Science.gov (United States)

McAleer, Ryan J.; Bish, David L.; Kunk, Michael J.; Sicard, Karri R.; Valley, Peter M.; Walsh, Gregory J.; Wathen, Bryan A.; Wintsch, R.P.

2016-01-01

We describe strain localization by a mixed process of reaction and microstructural softening in a lower greenschist facies ductile fault zone that transposes and replaces middle to upper amphibolite facies fabrics and mineral assemblages in the host schist of the Littleton Formation near Claremont, New Hampshire. Here, Na-poor muscovite and chlorite progressively replace first staurolite, then garnet, and finally biotite porphyroblasts as the core of the fault zone is approached. Across the transect, higher grade fabric-forming Na-rich muscovite is also progressively replaced by fabric-forming Na-poor muscovite. The mineralogy of the new phyllonitic fault-rock produced is dominated by Na-poor muscovite and chlorite together with late albite porphyroblasts. The replacement of the amphibolite facies porphyroblasts by muscovite and chlorite is pseudomorphic in some samples and shows that the chemical metastability of the porphyroblasts is sufficient to drive replacement. In contrast, element mapping shows that fabric-forming Na-rich muscovite is selectively replaced at high-strain microstructural sites, indicating that strain energy played an important role in activating the dissolution of the compositionally metastable muscovite. The replacement of strong, high-grade porphyroblasts by weaker Na-poor muscovite and chlorite constitutes reaction softening. The crystallization of parallel and contiguous mica in the retrograde foliation at the expense of the earlier and locally crenulated Na-rich muscovite-defined foliation destroys not only the metastable high-grade mineralogy, but also its stronger geometry. This process constitutes both reaction and microstructural softening. The deformation mechanism here was thus one of dissolution–precipitation creep, activated at considerably lower stresses than might be predicted in quartzofeldspathic rocks at the same lower greenschist facies conditions.

Partial root zone drying (PRD) sustains yield of potatoes (Solanum tuberosum L.) at reduced water supply

DEFF Research Database (Denmark)

Shahnazari, Ali; Andersen, Mathias Neumann; Liu, Fulai

2008-01-01

Partial root zone drying (PRD) is a new water-saving irrigation strategy being tested in many crop species. Until now it has not been investigated in potatoes (Solanum tuberosum L.). A field experiment on sandy soil in Denmark was conducted under a mobile rainout shelter to study effects of two...... subsurface drip irrigation treatments ((1) Full Irrigation (FI) receiving 100% of evaporative demand; and (2) PRD receiving 70% water of FI) on potato yield, tuber size, leaf water relations and irrigation water use efficiency (IWUE). The PRD treatment was started just after the end of tuber initiation...... for two months during tuber bulking and maturing stage and was shifted from one side to the other side of the plants every 5-10 days when FI plants had used 20-25 mm. Compared to FI plants, stomatal conductance was generally lower in the PRD-treated plants, whereas leaf water potential tended to be lower...

Partial-wave analysis of the reaction K−p → $\\lambda$ (1520) $\\pi$ in the energy region 1915 – 2170 MeV

CERN Document Server

Litchfield, P J; Baillon, Paul; Putzer, A; Schleich, H

1974-01-01

A partial-wave analysis has been carried out on the reaction K/sup -/p to Lambda (1520) pi to K/sup -/p pi /sup 0/. The Sigma (2030) is observed with an amplitude at resonance of 0.14+or-0.03. Evidence is also presented for the formation of the /sup 3///sub 2//sup -/ Sigma (1940). (14 refs).

Study of the dynamics of the MoO2-Mo2C system for catalytic partial oxidation reactions

Science.gov (United States)

Cuba Torres, Christian Martin

On a global scale, the energy demand is largely supplied by the combustion of non-renewable fossil fuels. However, their rapid depletion coupled with environmental and sustainability concerns are the main drivers to seek for alternative energetic strategies. To this end, the sustainable generation of hydrogen from renewable resources such as biodiesel would represent an attractive alternative solution to fossil fuels. Furthermore, hydrogen's lower environmental impact and greater independence from foreign control make it a strong contender for solving this global problem. Among a wide variety of methods for hydrogen production, the catalytic partial oxidation offers numerous advantages for compact and mobile fuel processing systems. For this reaction, the present work explores the versatility of the Mo--O--C catalytic system under different synthesis methods and reforming conditions using methyl oleate as a surrogate biodiesel. MoO2 exhibits good catalytic activity and exhibits high coke-resistance even under reforming conditions where long-chain oxygenated compounds are prone to form coke. Moreover, the lattice oxygen present in MoO2 promotes the Mars-Van Krevelen mechanism. Also, it is introduced a novel beta-Mo2C synthesis by the in-situ formation method that does not utilize external H2 inputs. Herein, the MoO 2/Mo2C system maintains high catalytic activity for partial oxidation while the lattice oxygen serves as a carbon buffer for preventing coke formation. This unique feature allows for longer operation reforming times despite slightly lower catalytic activity compared to the catalysts prepared by the traditional temperature-programmed reaction method. Moreover, it is demonstrated by a pulse reaction technique that during the phase transformation of MoO2 to beta-Mo2C, the formation of Mo metal as an intermediate is not responsible for the sintering of the material wrongly assumed by the temperature-programmed method.

Reaction phenomena of catalytic partial oxidation of methane under the impact of carbon dioxide addition and heat recirculation

International Nuclear Information System (INIS)

Chen, Wei-Hsin; Lin, Shih-Cheng

2015-01-01

The reaction phenomena of CPOM (catalytic partial oxidation of methane) in a Swiss-roll reactor are studied numerically where a rhodium-based catalyst bed is embedded at the center of the reactor. CO 2 is added into the feed gas and excess enthalpy recovery is performed to evaluate their influences on CPOM performance. In the study, the mole ratio of O 2 to CH 4 (O 2 /CH 4 ratio) is fixed at 0.5 and the mole ratio of CO 2 to O 2 (CO 2 /O 2 ratio) is in the range of 0–2. The results reveal that CO 2 addition into the influent has a slight effect on methane combustion, but significantly enhances dry reforming and suppresses steam reforming. The reaction extents of steam reforming and dry reforming in CPOM without heat recovery and CO 2 addition are in a comparable state. Once CO 2 is added into the feed gas, the dry reforming is enhanced, thereby dominating CH 4 consumption. Compared to the reactor without excess enthalpy recovery, heat recirculation drastically increases the maximum reaction temperature and CH 4 conversion in the catalyst bed; it also intensifies the H 2 selectivity, H 2 yield, CO 2 conversion, and syngas production rate. The predictions indicate that the heat recirculation is able to improve the syngas formation up to 45%. - Highlights: • Catalytic partial oxidation of methane with CO 2 addition and heat recovery is studied. • CO 2 addition has a slight effect on methane combustion. • CO 2 addition significantly enhances dry reforming and suppresses steam reforming. • Dry reforming dominates CH 4 consumption when CO 2 addition is large. • Heat recirculation can improve the syngas formation up to 45%

Spectral zone selection methodology for pebble bed reactors

International Nuclear Information System (INIS)

Mphahlele, Ramatsemela; Ougouag, Abderrafi M.; Ivanov, Kostadin N.; Gougar, Hans D.

2011-01-01

A methodology is developed for determining boundaries of spectral zones for pebble bed reactors. A spectral zone is defined as a region made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. The spectral zones are selected in such a manner that the difference (error) between the reference transport solution and the diffusion code solution takes a minimum value. This is achieved by choosing spectral zones through optimally minimizing this error. The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates errors in each zone. The selection of these spectral zones is such that the core calculation results based on diffusion theory are within an acceptable tolerance as compared to a proper transport reference solution. Through this work, a consistent approach for identifying spectral zones that yield more accurate diffusion results is introduced.

Partial wave analysis of the Q region in the reactions K-p→K-π+π-p and K-p→antikaon neutral π-π0p at 14.3GeV/c

International Nuclear Information System (INIS)

Tovey, S.N.; Hansen, J.D.; Paler, K.; Shah, T.P.; Borg, A.; Denegri, D.; Pons, Y.; Spiro, M.

1975-01-01

The reactions K - p→K - π + π - and K - p→ antikaon-neutral π - π 0 p at 14.3GeV/c has been studied using respectively 15992 and 3723 events. Partial wave analysis of the region 1.0 + but that the partial wave substrates have very different branching ratios into (rho) and K*π, the K*π component of the 1 + state being similar to the 1 + state of the 3π system produced in the reaction πp→(3π)p [fr

Design requirements for ERD in diffusion-dominated media: how do injection interval, bioactive zones and reaction kinetics affect remediation performance?

Science.gov (United States)

Chambon, J.; Lemming, G.; Manoli, G.; Broholm, M. M.; Bjerg, P.; Binning, P. J.

2011-12-01

Enhanced Reductive Dechlorination (ERD) has been successfully used in high permeability media, such as sand aquifers, and is considered to be a promising technology for low permeability settings. Pilot and full-scale applications of ERD at several sites in Denmark have shown that the main challenge is to get contact between the injected bacteria and electron donor and the contaminants trapped in the low-permeability matrix. Sampling of intact cores from the low-permeability matrix has shown that the bioactive zones (where degradation occurs) are limited in the matrix, due to the slow diffusion transport processes, and this affects the timeframes for the remediation. Due to the limited ERD applications and the complex transport and reactive processes occurring in low-permeability media, design guidelines are currently not available for ERD in such settings, and remediation performance assessments are limited. The objective of this study is to combine existing knowledge from several sites with numerical modeling to assess the effect of the injection interval, development of bioactive zones and reaction kinetics on the remediation efficiency for ERD in diffusion-dominated media. A numerical model is developed to simulate ERD at a contaminated site, where the source area (mainly TCE) is located in a clayey till with fractures and interbedded sand lenses. Such contaminated sites are common in North America and Europe. Hydro-geological characterization provided information on geological heterogeneities and hydraulic parameters, which are relevant for clay till sites in general. The numerical model couples flow and transport in the fracture network and low-permeability matrix. Sequential degradation of TCE to ethene is modeled using Monod kinetics, and the kinetic parameters are obtained from laboratory experiments. The influence of the reaction kinetics on remediation efficiency is assessed by varying the biomass concentration of the specific degraders. The injected

Partial-wave analysis of the reaction $K^{-}$ p -> $\\overline{K} \\delta$ (1230) in the energy region 1915–2170 MeV

CERN Document Server

Litchfield, P J; Baillon, Paul; Albrecht, A; Putzer, A

1974-01-01

A partial-wave analysis has been carried out on the reaction K/sup -/p to K/sup -/ Delta /sup +/(1230) to K/sup -/p pi /sup 0/ in the centre of mass energy region 1915-2170 MeV. The Sigma (2030) is observed with an amplitude at resonance of 0.16+or-0.03. Strong formation of the /sup 3///sub 2//sup -/ Sigma (1940) is also indicated. (9 refs).

Electric conductivity for laboratory and field monitoring of induced partial saturation (IPS) in sands

Science.gov (United States)

Kazemiroodsari, Hadi

Liquefaction is loss of shear strength in fully saturated loose sands caused by build-up of excess pore water pressure, during moderate to large earthquakes, leading to catastrophic failures of structures. Currently used liquefaction mitigation measures are often costly and cannot be applied at sites with existing structures. An innovative, practical, and cost effective liquefaction mitigation technique titled "Induced Partial Saturation" (IPS) was developed by researchers at Northeastern University. The IPS technique is based on injection of sodium percarbonate solution into fully saturated liquefaction susceptible sand. Sodium percarbonate dissolves in water and breaks down into sodium and carbonate ions and hydrogen peroxide which generates oxygen gas bubbles. Oxygen gas bubbles become trapped in sand pores and therefore decrease the degree of saturation of the sand, increase the compressibility of the soil, thus reduce its potential for liquefaction. The implementation of IPS required the development and validation of a monitoring and evaluation technique that would help ensure that the sands are indeed partially saturated. This dissertation focuses on this aspect of the IPS research. The monitoring system developed was based on using electric conductivity fundamentals and probes to detect the transport of chemical solution, calculate degree of saturation of sand, and determine the final zone of partial saturation created by IPS. To understand the fundamentals of electric conductivity, laboratory bench-top tests were conducted using electric conductivity probes and small specimens of Ottawa sand. Bench-top tests were used to study rate of generation of gas bubbles due to reaction of sodium percarbonate solution in sand, and to confirm a theory based on which degree of saturation were calculated. In addition to bench-top tests, electric conductivity probes were used in a relatively large sand specimen prepared in a specially manufactured glass tank. IPS was

Design requirements for ERD in diffusion-dominated media: how do injection interval, bioactive zones and reaction kinetics affect remediation performance?

DEFF Research Database (Denmark)

Chambon, Julie Claire Claudia; Lemming, Gitte; Manoli, Gabriele

is to get contact between the injected bacteria and electron donor and the contaminants trapped in the low-permeability matrix. Sampling of intact cores from the low-permeability matrix has shown that the bioactive zones (where degradation occurs) are limited in the matrix, due to the slow diffusion...... is developed to simulate ERD at a contaminated site, where the source area (mainly TCE) is located in a clayey till with fractures and interbedded sand lenses. Such contaminated sites are common in North America and Europe. Hydro-geological characterization provided information on geological heterogeneities...... experiments. The influence of the reaction kinetics on remediation efficiency is assessed by varying the biomass concentration of the specific degraders. The injected reactants (donor and bacteria) are assumed to spread in horizontal injection zones of various widths, depending on the development of bioactive...

Dislocation arrangement in the plastic zone for propagating cracks in nickel

International Nuclear Information System (INIS)

Kobayashi, S.; Ohr, S.M.

1985-01-01

Since nickel is a metal of high stacking fault energy, it is of interest to study the arrangement of dislocations in the plastic zone for propagating cracks and to compare the results with those found in metals of low stacking fault energy. It has been found that two distinct distributions of dislocations in the plastic zone are associated with cracks in nickel. In one of these, the plastic zone appeared as a thin ribbon and consisted of a number of partial dislocations with stacking fault fringes. From contrast analysis and stereoscopic observations, the crack was found to be approximately mode III type, and the plane of the plastic zone was identified as (111). The crack geometry was very similar to that observed in metals of low stacking fault energy, namely, stainless steel and copper. The second type of plastic zone observed was not in the form of a thin ribbon; that is, the dislocations in the plastic zone were not split into partial dislocations. Since the dislocations were not split, they cross-slipped readily from the original slip plane and formed a broad plastic zone

Reducing tool wear by partial cladding of critical zones in hot form tool by laser metal deposition

Science.gov (United States)

Vollmer, Robert; Sommitsch, Christof

2017-10-01

This paper points out a production method to reduce tool wear in hot stamping applications. Usually tool wear can be observed at locally strongly stressed areas superimposed with gliding movement between blank and tool surface. The shown solution is based on a partial laser cladding of the tool surface with a wear resistant coating to increase the lifespan of tool inserts. Preliminary studies showed good results applying a material combination of tungsten carbide particles embedded in a metallic matrix. Different Nickel based alloys welded on hot work tool steel (1.2343) were tested mechanically in the interface zone. The material with the best bonding characteristic is chosen and reinforced with spherical tungsten carbide particles in a second laser welding step. Since the machining of tungsten carbides is very elaborate a special manufacturing strategy is developed to reduce the milling effort as much as possible. On special test specimens milling tests are carried out to proof the machinability. As outlook a tool insert of a b-pillar is coated to perform real hot forming tests.

Knock-out reactions

International Nuclear Information System (INIS)

de Forest, T. Jr.

1977-01-01

It is pointed out that the primary motivation for performing high energy single nucleon knock-out reactions is based on the concept of quasi-elastic scattering. The validity of and corrections to the partial wave impulse approximation and kinematical invariance of knock-out reactions and tests of the reaction mechanism are treated. The effect of distortions on the momentum distribution in the effective momentum approximation for given parameters are plotted. 12 references

Root and leaf abscisic acid concentration impact on gas exchange in tomato (Lycopersicon esculentum Mill plants subjected to partial root-zone drying

Directory of Open Access Journals (Sweden)

Maria Valerio

2017-03-01

Full Text Available Partial root-zone drying (PRD is a deficit irrigation technique with great potential for water saving. A split-root experiment was conducted on tomato in controlled environment in order to test the response of two long-time storage cultivars to PRD. Ponderosa tomato, a cultivar with yellow fruits, was compared to Giallo tondo di Auletta, a local cultivar from southern Campania (Italy. Plants were subjected to three irrigation treatments: plants receiving an amount of water equivalent to 100% of plant evapotranspiration (V100; plants in which 50% of the amount of water given to V100 was supplied (V50; and plants where one root compartment was irrigated at 50% of water requirements and the other compartment was allowed to dry, and thereafter every side was rewetted alternatively (PRD. The highest levels of leaf abscisic acid (ABA [on average equal to 104 ng g–1 fresh weight FW] were measured in PRD and V50, at 70 days after transplantation. Root ABA concentration in both PRD and V50 reached mean values of 149 ng g–1 FW. There were differences for the irrigation regime in root ABA biosynthesis and accumulation under partial root-zone drying and conventional deficit irrigation (V50. Assimilation rate, stomatal conductance and intercellular CO2 concentration decreased in relation to the irrigation regime by 22, 36 and 12%, respectively, in PRD, V50 and V100 at 50 days after transplantation. Ponderosa variety accumulated 20% more dry matter than Auletta and significant differences were observed in leaf area. In both PRD and V50 of the two varieties, it was possible to save on average 46% of water. Our results indicate that there is still space to optimise the PRD strategy, to further improve the cumulative physiological effects of the root-sourced signaling system.

An Equation Governing Ultralow-Velocity Zones: Implications for Holes in the ULVZ, Lateral Chemical Reactions at the Core-Mantle Boundary, and Damping of Heat Flux Variations in the Core

Science.gov (United States)

Hernlund, J. W.; Matsui, H.

2017-12-01

Ultralow-velocity zones (ULVZ) are increasingly illuminated by seismology, revealing surprising diversity in size, shape, and physical characteristics. The only viable hypotheses are that ULVZs are a compositionally distinct FeO-enriched dense material, which could have formed by fractional crystallization of a basal magma ocean, segregation of subducted banded iron formations, precipitation of solids from the outer core, partial melting and segregation of iron-rich melts from subducted basalts, or most likely a combination of many different processes. But many questions remain: Are ULVZ partially molten in some places, and not in others? Are ULVZ simply the thicker portions of an otherwise global thin layer, covering the entire CMB and thus blocking or moderating chemical interactions between the core and overlying mantle? Is such a layer inter-connected and able to conduct electrical currents that allow electro-magnetic coupling of core and mantle angular momentum? Are they being eroded and shrinking in size due to viscous entrainment, or is more material being added to ULVZ over time? Here we derive an advection-diffusion-like equation that governs the dynamical evolution of a chemically distinct ULVZ. Analysis of this equation shows that ULVZ should become readily swept aside by viscous mantle flows at the CMB, exposing "ordinary mantle" to the top of the core, thus inducing chemical heterogeneity that drives lateral CMB chemical reactions. These reactions are correlated with heat flux, thus maintaining large-scale pressure variations atop the core that induce cyclone-like flows centered around ULVZ and ponded subducted slabs. We suggest that turbulent diffusion across adjacent cyclone streams inside a stratified region atop the core readily accommodates lateral transport and re-distribution of components such as O and Si, in addition to heat. Our model implies that the deeper core is at least partly shielded from the influence of strong heat flux variations at

49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

Science.gov (United States)

2010-10-01

... authority. FRA believes that it will be very useful to include these organizations in the planning process... implementation process. This section also discusses Partial (e.g. night time only quiet zones) and Intermediate... provides four basic ways in which a quiet zone may be established. Creation of both New Quiet Zones and Pre...

Characterisation of weld zone reactions in dissimilar glass-to-aluminium pulsed picosecond laser welds

Energy Technology Data Exchange (ETDEWEB)

Ciuca, Octav P., E-mail: octav.ciuca@manchester.ac.uk [School of Materials, University of Manchester, Manchester, M13 9PL (United Kingdom); Carter, Richard M. [Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS (United Kingdom); Prangnell, Philip B. [School of Materials, University of Manchester, Manchester, M13 9PL (United Kingdom); Hand, Duncan P. [Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS (United Kingdom)

2016-10-15

Precision welded joints, produced between fused silica glass and aluminium by a newly-developed picosecond-pulse laser technique, have been analysed for the first time using a full range of electron microscopy methods. The welds were produced as lap joints by focusing a 1.2 μm diameter laser beam through the transparent glass top sheet, slightly below the surface of the metal bottom sheet. Despite the extremely short interaction time, extensive reaction was observed in the weld zone, which involved the formation of nanocrystalline silicon and at least two transitional alumina phases, γ- and δ-Al{sub 2}O{sub 3}. The weld formation process was found to be complex and involved: the formation of a constrained plasma cavity at the joint interface, non-linear absorption in the glass, and the creation of multiple secondary keyholes in the metal substrate by beam scattering. The joint area was found to expand outside of the main interaction volume, as the energy absorbed into the low conductivity and higher melting point silica glass sheet melted the aluminium surface across a wider contact area. The reasons for the appearance of nanocrystalline Si and transitional alumina reaction products within the welds are discussed. - Highlights: •Pulsed laser welding of dissimilar materials causes extensive chemical reactivity. •Metastable Al{sub 2}O{sub 3} phases form due to laser-induced highly-transient thermal regime. •Fused silica is reduced by Al to form nanocrystalline Si. •Mechanism of joint formation is discussed.

A parametric investigation of hydrogen hcci combustion using a multi-zone model approach

International Nuclear Information System (INIS)

Komninos, N.P.; Hountalas, D.T.; Rakopoulos, C.D.

2007-01-01

The purpose of the present study is to examine the effect of various operating variables of a homogeneous charge compression ignition (HCCI) engine fueled with hydrogen, using a multi-zone model developed by the authors. The multi-zone model consists of zones, which are allotted spatial locations within the combustion chamber. The model takes into account heat transfer between the zones and the combustion chamber walls, providing a spatial temperature distribution during the closed part of the engine cycle, i.e. compression, combustion and expansion. Mass transfer between zones is also accounted for, based on the geometric configuration of the zones, and includes the flow of mass in and out of the crevice regions, represented by the crevice zone. Combustion is incorporated using chemical kinetics based on a chemical reaction mechanism for the oxidation of hydrogen. This chemical reaction mechanism also includes the reactions for nitrogen oxides formation. Using the multi-zone model a parametric investigation is conducted, in order to determine the effect of engine speed, equivalence ratio, compression ratio, inlet pressure and inlet temperature, on the performance, combustion characteristics and emissions of an HCCI engine fueled with hydrogen

Investigations of chemical reactions between U-Zr alloy and FBR cladding materials

International Nuclear Information System (INIS)

Ishii, Tetsuya; Ukai, Shigeharu

2005-07-01

U-Pu-Zr alloys are candidate materials for commercial FBR fuel. However, informations about chemical reactions with cladding materials developed by JNC for commercial FBR have not been well obtained. In this work, the reaction zones formed in four diffusion couples U-10wt.%Zr/PNC-FMS, U-10wt.%Zr/9Cr-ODS, U-10wt.%Zr/12Cr-ODS, and U-10wt.%Zr/Fe at about 1013K have been examined and following results were obtained. 1) At about 1013K, in the U-10wt.%Zr/Fe couple, the liquid phase zones were obtained. In the other couples U-10wt.%Zr/PNC-FMS, U-10wt.%Zr/9Cr-ODS and U-10wt.%Zr/12Cr-ODS, no liquid phase zones were obtained. The obtained chemical reaction zones in the later 3 couples were similar to the reported ones obtained in U-Zr/Fe couples without liquid phase formation. In comparison with the reaction zones obtained in the U-10wt.%Zr/Fe couple, the reaction zones inside cladding materials obtained in the PNC-FMS, 9Cr-ODS, and 12Cr-ODS couples were thin. 2) From the investigations of relationship between the obtained depths of the chemical reaction zones inside cladding materials and composition of the cladding materials, it was considered that the depth of chemical reaction zone would depend on the Cr content of the cladding materials and the depth would decrease with increasing Cr content, resulting in prevention of liquid phase formation. 3) From the investigations of the mechanisms of chemical reactions between U-Pu-Zr/cladding materials, it was considered that the same effect of Cr obtained in the U-Zr/cladding materials would be expected in U-Pu-Zr/cladding materials. Those seemed to indicate that the threshold temperatures of liquid phase formation for U-Pu-Zr/PNC-FMS, U-Pu-Zr/9Cr-ODS, and U-Pu-Zr/12Cr-ODS might be higher than that for U-Pu-Zr/Fe. (author)

Metamorphic history of garnet-rich gneiss at Ktiš in the Lhenice shear zone, Moldanubian Zone of the southern Bohemian Massif, inferred from inclusions and compositional zoning of garnet

Czech Academy of Sciences Publication Activity Database

Kobayashi, T.; Hirajima, T.; Kawakami, T.; Svojtka, Martin

2011-01-01

Roč. 124, 1/2 (2011), s. 46-65 ISSN 0024-4937 Institutional research plan: CEZ:AV0Z30130516 Keywords : Bohemian Massif * Lhenice shear zone * garnet * P-T path * partial melting Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.246, year: 2011

Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction

Science.gov (United States)

Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

2010-08-03

A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler

Directory of Open Access Journals (Sweden)

Jun-Xia Zhang

2016-03-01

Full Text Available Because the air-staged combustion technology is one of the key technologies with low investment running costs and high emission reduction efficiency for the pulverized boiler, it is important to reveal the chemical reaction kinetics mechanism for developing various technologies of nitrogen oxide reduction emissions. At the present work, a three-dimensional mesh model of the large-scale four corner tangentially fired boiler furnace is established with the GAMBIT pre-processing of the FLUENT software. The partial turbulent premixed and diffusion flame was simulated for the air-staged combustion processing. Parameters distributions for the air-staged and no the air-staged were obtained, including in-furnace flow field, temperature field and nitrogen oxide concentration field. The results show that the air-staged has more regular velocity field, higher velocity of flue gas, higher turbulence intensity and more uniform temperature of flue gas. In addition, a lower negative pressure zone and lower O2 concentration zone is formed in the main combustion zone, which is conducive to the NO of fuel type reduced to N2, enhanced the effect of NOx reduction. Copyright © 2016 BCREC GROUP. All rights reserved Received: 5th November 2015; Revised: 14th January 2016; Accepted: 16th January 2016  How to Cite: Zhang, J.X., Zhang, J.F. (2016. Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 100-108. (doi:10.9767/bcrec.11.1.431.100-108 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.431.100-108

The Pozzolanic reaction of silica fume

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede

2012-01-01

Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the ......Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone....... In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy...

Sodium-concrete reaction model development

International Nuclear Information System (INIS)

Nguyen, D.H.; Muhlestein, L.D.; Postma, A.K.

1982-07-01

Major observations have been formulated after reviewing test results for over 100 sodium-concrete reaction tests. The observations form the basis for developing a mechanistic model to predict the transient behavior of sodium-concrete reactions. The major observations are listed. Mechanisms associated with sodium and water transport to the reaction zone are identified, and represented by appropriate mathematical expressions. The model attempts to explain large-scale, long-term (100 h) test results were sodium-concrete reactions terminated even in the presence of unreacted sodium and concrete

Deciduous Forest Zone of Ghana

African Journals Online (AJOL)

carbon, nitrogen and phosphorus contents, soil reaction and base saturation with highest values in the topsoil due to the .... These soils occur extensively in the. Zone ... tion with 6M sulphuric acid. .... which will lead to removal of topsoil litter,.

Reactions of laser ablated uranium with nitrogen studied using matrix isolation spectroscopy

International Nuclear Information System (INIS)

Sankaran, K.; Sundararajan, K.; Viswanathan, K.S.

1999-01-01

Unusual reactions were found to occur when uranium was laser ablated in the presence of nitrogen. The reaction products were trapped in a rigid inert gas matrix and studied using infrared spectroscopy. The species formed were strongly dependent on the partial pressure of nitrogen in the matrix gas used during the ablation process; at low nitrogen partial pressures uranium dinitride (NUN) was the major reaction product, while at high partial pressures of nitrogen the mononitride, UN, was the predominant product. (author)

Adiabatic flame temperature of sodium combustion and sodium-water reaction

International Nuclear Information System (INIS)

Okano, Y.; Yamaguchi, A.

2001-01-01

In this paper, background information of sodium fire and sodium-water reaction accidents of LMFBR (liquid metal fast breeder reactor) is mentioned at first. Next, numerical analysis method of GENESYS is described in detail. Next, adiabatic flame temperature and composition of sodium combustion are analyzed, and affect of reactant composition, such oxygen and moisture, is discussed. Finally, adiabatic reaction zone temperature and composition of sodium-water reaction are calculated, and affects of reactant composition, sodium vaporization, and pressure are stated. Chemical equilibrium calculation program for generic chemical system (GENESYS) is developed in this study for the research on adiabatic flame temperature of sodium combustion and adiabatic reaction zone temperature of sodium-water reaction. The maximum flame temperature of the sodium combustion is 1,950 K at the standard atmospheric condition, and is not affected by the existence of moisture. The main reaction product is Na 2 O (l) , and in combustion in moist air, with NaOH (g) . The maximum reaction zone temperature of the sodium-water reaction is 1,600 K, and increases with the system pressure. The main products are NaOH (g) , NaOH (l) and H2 (g) . Sodium evaporation should be considered in the cases of sodium-rich and high pressure above 10 bar

Small water/steam leaks in sodium heated steam generators: Evaluation of the reaction zone - effects on 2 1/4 Cr 1 Mo structural material

International Nuclear Information System (INIS)

Dumm, K.

1975-01-01

On the basis of experimental data the geometry of a small leak reaction zone can be predicted for given leak sizes and steam generator operation conditions. The effects of small leaks on 2 1/4 Cr 1 Mo material have been studied and completed with test results from foreign investigators. The results have to be considered as preliminary ones which have to be further qualified by additional information. (author)

Small water/steam leaks in sodium heated steam generators: Evaluation of the reaction zone - effects on 2 1/4 Cr 1 Mo structural material

Energy Technology Data Exchange (ETDEWEB)

Dumm, K

1975-07-01

On the basis of experimental data the geometry of a small leak reaction zone can be predicted for given leak sizes and steam generator operation conditions. The effects of small leaks on 2 1/4 Cr 1 Mo material have been studied and completed with test results from foreign investigators. The results have to be considered as preliminary ones which have to be further qualified by additional information. (author)

Reactor Meltdown: Critical Zone Processes In Siliciclastics Unlikely To Be Directly Transferable To Carbonates

Science.gov (United States)

Gulley, J. D.; Cohen, M. J.; Kramer, M. G.; Martin, J. B.; Graham, W. D.

2013-12-01

Carbonate terrains cover 20% of Earth's ice-free land and are modified through interactions between rocks, water and biota that couple ecosystems processes to weathering reactions within the critical zone. Weathering in carbonate systems differs from the Critical Zone Reactor model developed for siliciclastic systems because reactions in siliciclastic critical zones largely consist of incongruent weathering (e.g., feldspar to secondary clay minerals) that typically occur in the soil zone within a few meters of the land surface. These incongruent reactions create regolith, which is removed by physical transport mechanisms that drive landscape denudation. In contrast, carbonate critical zones are mostly composed of homogeneous and soluble minerals, which dissolve congruently with the weathering products exported in solution, limiting regolith in the soil mantle to small amounts of insoluble residues. These reactions can extend to depths greater than 2 km below the surface. As water at the land surface drains preferentially through vertical joints and horizontal bedding planes of the carbonate critical zones, it is 'charged' with biologically-derived carbon dioxide, which decreases pH, dissolves carbonate rock, and enlarges subsurface flowpaths through feedbacks between flow and dissolution. Caves are extreme end products of this process and are key morphological features of carbonate critical zones. Caves link surface processes to the deep subsurface and serve as efficient delivery agents for oxygen, carbon and nutrients to zones within the critical zone that are deficient in all three, interrupting vertical and horizontal chemical gradients that would exist if caves were not present. We present select data from air and water-filled caves in the upper Floridan aquifer, Florida, USA, that demonstrate how caves, acting as very large preferential flow paths, alter processes in carbonate relative to siliciclastic critical zones. While caves represent an extreme end

C-O-H-N fluids circulations and graphite precipitation in reactivated Hudsonian shear zones during basement uplift of the Wollaston-Mudjatik Transition Zone: Example of the Cigar Lake U deposit

Science.gov (United States)

Martz, Pierre; Cathelineau, Michel; Mercadier, Julien; Boiron, Marie-Christine; Jaguin, Justine; Tarantola, Alexandre; Demacon, Mickael; Gerbeaud, Olivier; Quirt, David; Doney, Amber; Ledru, Patrick

2017-12-01

Graphitic shear zones are spatially associated with unconformity-related uranium deposits that are located around the unconformity between the strata of the Paleo- to Mesoproterozoic Athabasca Basin (Saskatchewan, Canada) and its underlying Archean to Paleoproterozoic basement. The present study focuses on basement-hosted ductile-brittle graphitic shear zones near the Cigar Lake U deposit, one of the largest unconformity-related U deposits. The goal of the study is to decipher the pre-Athabasca Basin fluid migration history recorded within such structures and its potential role on the formation of such exceptional deposit. Dominantly C-O-H(-N) metamorphic fluids have been trapped in Fluid Inclusion Planes (FIPs) in magmatic quartz within ductile-brittle graphitic shear zones active during retrograde metamorphism associated with the formation of the Wollaston-Mudjatik Transition Zone (WMTZ) between ca. 1805 and 1720 Ma. Such fluids show a compositional evolution along the retrograde path, from a dense and pure CO2 fluid during the earliest stages, through a lower density CO2 ± CH4-N2 (± H2O) fluid and, finally, to a very low density CH4-N2 fluid. Statistical study of the orientation, distribution, proportion, and chemical characterization of the FIPs shows that: i) CO2 (δ13CCO2 around - 9‰ PDB) from decarbonation reactions and/or partial water-metamorphic graphite equilibrium initially migrated regionally and pervasively under lithostatic conditions at about 500 to 800 °C and 150 to 300 MPa. Such P-T conditions attest to a high geothermal gradient of around 60 to 90 °C/km, probably related to rapid exhumation of the basement or a large-scale heat source. ii) Later brittle reactivation of the shear zone at around 450 °C and 25-50 MPa favored circulation of CO2-CH4-N2(± H2O) fluids in equilibrium with metamorphic graphite (δ13CCO2 around - 14‰) under hydrostatic conditions and only within the shear zones. Cooling of these fluids and the water uptake linked

Magma-assisted strain localization in an orogen-parallel transcurrent shear zone of southern Brazil

Science.gov (United States)

Tommasi, AndréA.; Vauchez, Alain; Femandes, Luis A. D.; Porcher, Carla C.

1994-04-01

In a lithospheric-scale, orogen-parallel transcurrent shear zone of the Pan-African Dom Feliciano belt of southern Brazil, two successive generations of magmas, an early calc-alkaline and a late peraluminous, have been emplaced during deformation. Microstructures show that these granitoids experienced a progressive deformation from magmatic to solid state under decreasing temperature conditions. Magmatic deformation is indicated by the coexistence of aligned K-feldspar, plagioclase, micas, and/or tourmaline with undeformed quartz. Submagmatic deformation is characterized by strain features, such as fractures, lattice bending, or replacement reactions affecting only the early crystallized phases. High-temperature solid-state deformation is characterized by extensive grain boundary migration in quartz, myrmekitic K-feldspar replacement, and dynamic recrystallization of both K-feldspar and plagioclase. Decreasing temperature during solid-state deformation is inferred from changes in quartz crystallographic fabrics, decrease in grain size of recrystallized feldspars, and lower Ti amount in recrystallized biotites. Final low-temperature deformation is characterized by feldspar replacement by micas. The geochemical evolution of the synkinematic magmatism, from calc-alkaline metaluminous granodiorites with intermediate 87Sr/86Sr initial ratio to peraluminous granites with very high 87Sr/86Sr initial ratio, suggests an early lower crustal source or a mixed mantle/crustal source, followed by a middle to upper crustal source for the melts. Shearing in lithospheric faults may induce partial melting in the lower crust by shear heating in the upper mantle, but, whatever the process initiating partial melting, lithospheric transcurrent shear zones may collect melt at different depths. Because they enhance the vertical permeability of the crust, these zones may then act as heat conductors (by advection), promoting an upward propagation of partial melting in the crust

[Measurements of tibio-femoral contact area after experimental partial and subtotal meniscectomie (author's transl)].

Science.gov (United States)

Hehne, H J; Riede, U N; Hauschild, G; Schlageter, M

1981-02-01

By means of section material, 24 partial and 58 subtotal meniscectomies were performed and the loss of tibio-femoral contact was evaluated by the Touchier-method planimetrically. In cases of partial resection this loss was 12% only, where as in subtotal resection 46%, where by the remaining contact zones lay in the central-, anyway meniscusfree area. The diagram of the chondral splitting lines showed a maximum of compression here, consecutively the remaining contact zone is reduced to the in earlier times most affected cartilage areas. The result correlates to the appearance of chondromalacies of the central tibial plateau in our own section cases and of postoperative osteoarthritis after subtotal meniscectomies in literature. Subtotal meniscectomies lead to incongruence and increased pressure. a pseudo-regeneration seems not to compensate the meniscus function sufficiently. A result for the clinic one should, when possible, resect menisci only partially.

Dynamic loadings of sodium-water reactions in LMFBR and fusion power designs

Energy Technology Data Exchange (ETDEWEB)

Chan, C. K.

1977-07-01

In liquid metal fast breeder reactor and lithium cooled fusion reactor, a sodium loop is being proposed to transfer heat from the primary coolant loop to the steam turbine cycle. Although by careful design and quality assurance programs, the probability for steam generator tube failure can be minimized, failure will still occur. The direct contact of sodium and water would cause a chemical reaction where hydrogen and sodium compounds are produced. This paper presents an evaluation of the potential hazards as a result of such a reaction. An analytical method is developed to investigate the extent of the reaction zone and the propagation of the pressure wave in the sodium system. In the calculation, the chemical reaction is assumed to be instantaneous, governed by the equation 2Na(l)+H/sub 2/O(l)..-->..Na/sub 2/O(l)+H/sub 2/(g)+31.4 K cal/gm. mole. Both the temperature and pressure rise in the reaction zone can be established from the energy balance and the equation of state for the gaseous product. As a consequence of the energy released, the chemical products suddenly expand with a high velocity. The expansion also generates a shock wave in both the water and the sodium systems. Results indicate that the reaction zone can expand in a rate of 1500 ft/sec and a shock wave with initial strength of 2300 atmospheres propagates with a speed of 8000 ft/sec into the sodium system. The propagating characteristics of the shock wave are obtained by solving the basic fluid equations. The shock wave decays rapidly, in the neighborhood of milliseconds, as soon as the reaction zone stops to expand. The decrease in the reaction zone pressure allows more water to react with the sodium and a second pulse is generated.

Dynamic loadings of sodium-water reactions in LMFBR and fusion power designs

International Nuclear Information System (INIS)

Chan, C.K.

1977-01-01

In liquid metal fast breeder reactor and lithium cooled fusion reactor, a sodium loop is being proposed to transfer heat from the primary coolant loop to the steam turbine cycle. Although by careful design and quality assurance programs, the probability for steam generator tube failure can be minimized, failure will still occur. The direct contact of sodium and water would cause a chemical reaction where hydrogen and sodium compounds are produced. This paper presents an evaluation of the potential hazards as a result of such a reaction. An analytical method is developed to investigate the extent of the reaction zone and the propagation of the pressure wave in the sodium system. In the calculation, the chemical reaction is assumed to be instantaneous, governed by the equation 2Na(l)+H 2 O(l)→Na 2 O(l)+H 2 (g)+31.4 K cal/gm. mole. Both the temperature and pressure rise in the reaction zone can be established from the energy balance and the equation of state for the gaseous product. As a consequence of the energy released, the chemical products suddenly expand with a high velocity. The expansion also generates a shock wave in both the water and the sodium systems. Results indicate that the reaction zone can expand in a rate of 1500 ft/sec and a shock wave with initial strength of 2300 atmospheres propagates with a speed of 8000 ft/sec into the sodium system. The propagating characteristics of the shock wave are obtained by solving the basic fluid equations. The shock wave decays rapidly, in the neighborhood of milliseconds, as soon as the reaction zone stops to expand. The decrease in the reaction zone pressure allows more water to react with the sodium and a second pulse is generated

Driving Ability of HMX based Aluminized Explosive Affected by the Reaction Degree of Aluminum Powder

Science.gov (United States)

Duan, Yingliang

2017-06-01

Due to the time scale of aluminum reaction, the detonation process of the aluminized explosive becomes very complex, and there is less agreement on the reaction mechanism of aluminum powder. If the reaction of aluminum occurs in the reaction zone, the energy released will further strengthen the work ability of detonation wave. So it is very important for characterizing the detonation parameters and detonation driving ability to accurately understand the role of aluminum powder in the reaction zone. In this paper, detonation driving process of HMX based aluminized explosive was studied by cylinder test, obtaining the expansion track of cylinder wall. In order to further research the reaction degree (λ) of aluminum in the reaction zone, the thermodynamic program VHL was used to calculate the detonation process at different reaction degrees, obtaining the parameters of detonation products thermodynamic state. Using the dynamic software LS-DYNA and the JWL equation of state by fitting the pressure and relative volume relationship, the cylinder test was simulated. Compared with the experimental results, when the reaction degree is 20%, the driving ability is found to be in agreement with measured ones. It is concluded that the driving ability of HMX based aluminized explosive can be more accurately characterized by considering the reaction degree of aluminum powder in the reaction zone.

Calculation of the energy of explosives with a partial reaction model. Comparison with cylinder test data

Energy Technology Data Exchange (ETDEWEB)

Sanchidrian, Jose A.; Lopez, Lina M. [Universidad Politecnica de Madrid - E.T.S.I. Minas, Rios Rosas 21, E-28003 Madrid (Spain)

2006-02-15

The energy delivered by explosives is described by means of the useful expansion work along the isentrope of the detonation products. A thermodynamic code (W-DETCOM) is used, in which a partial reaction model has been implemented. In this model, the reacted fraction of the explosive in the detonation state is used as a fitting factor so that the calculated detonation velocity meets the experimental value. Calculations based on such a model have been carried out for a number of commercial explosives of ANFO and emulsion types. The BKW (Becker-Kistiakowsky-Wilson) equation of state is used for the detonation gases with the Sandia parameter set (BKWS). The energy delivered in the expansion (useful work) is calculated, and the values obtained are compared with the Gurney energies from cylinder test data at various expansion ratios. The expansion work values obtained are much more realistic than those from an ideal detonation calculation and, in most cases, the values predicted by the calculation are in good agreement with the experimental ones. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

A partial wave analysis of world data for the reaction π-p → K0Λ from threshold to 2350 MeV/c

International Nuclear Information System (INIS)

Baker, R.D.; Blissett, J.A.; Bloodworth, I.J.

1977-06-01

All available world data for the reaction π - p → K 0 Λ up to 2350 MeV/c incident momentum have been analysed using both the Barrelet (Nuovo Cimento; 8A:331 (1972)) zero technique and a conventional energy-dependent fit. The results of the two methods are in good agreement. Resonances are required in the S 11 , P 11 , P 13 and D 13 partial waves. There is also an enhancement in the D 15 wave around 1900 MeV. No other resonances are required. (author)

The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

KAUST Repository

Elbaz, Ayman M.

2015-08-29

The stability limits, the stabilization mechanism, and the flow field structure of highly stabilized partially premixed methane flames in a concentric flow conical nozzle burner with air co-flow have been investigated and presented in this work. The stability map of partial premixed flames illustrates that the flames are stable between two extinction limits. A low extinction limit when partial premixed flames approach non-premixed flame conditions, and a high extinction limit, with the partial premixed flames approach fully premixed flame conditions. These two limits showed that the most stable flame conditions are achieved at a certain degree of partial premixed. The stability is improved by adding air co-flow. As the air co-flow velocity increases the most stable flames are those that approach fully premixed. The turbulent flow field of three flames at 0, 5, 10 m/s co-flow velocity are investigated using Stereo Particle Image Velocimetry (SPIV) in order to explore the improvement of the flame stability due to the use of air co-flow. The three flames are all at a jet equivalence ratio (Φj) of 2, fixed level of partial premixing and jet Reynolds number (Rej) of 10,000. The use of co-flow results in the formation of two vortices at the cone exit. These vortices act like stabilization anchors for the flames to the nozzle tip. With these vortices in the flow field, the reaction zone shifts toward the reduced turbulence intensity at the nozzle rim of the cone. Interesting information about the structure of the flow field with and without co-flow are identified and reported in this work.

Mass Transfer Limited Enhanced Bioremediation at Dnapl Source Zones: a Numerical Study

Science.gov (United States)

Kokkinaki, A.; Sleep, B. E.

2011-12-01

The success of enhanced bioremediation of dense non-aqueous phase liquids (DNAPLs) relies on accelerating contaminant mass transfer from the organic to the aqueous phase, thus enhancing the depletion of DNAPL source zones compared to natural dissolution. This is achieved by promoting biological activity that reduces the contaminant's aqueous phase concentration. Although laboratory studies have demonstrated that high reaction rates are attainable by specialized microbial cultures in DNAPL source zones, field applications of the technology report lower reaction rates and prolonged remediation times. One possible explanation for this phenomenon is that the reaction rates are limited by the rate at which the contaminant partitions from the DNAPL to the aqueous phase. In such cases, slow mass transfer to the aqueous phase reduces the bioavailability of the contaminant and consequently decreases the potential source zone depletion enhancement. In this work, the effect of rate limited mass transfer on bio-enhanced dissolution of DNAPL chlorinated ethenes is investigated through a numerical study. A multi-phase, multi-component groundwater transport model is employed to simulate DNAPL mass depletion for a range of source zone scenarios. Rate limited mass transfer is modeled by a linear driving force model, employing a thermodynamic approach for the calculation of the DNAPL - water interfacial area. Metabolic reductive dechlorination is modeled by Monod kinetics, considering microbial growth and self-inhibition. The model was utilized to identify conditions in which mass transfer, rather than reaction, is the limiting process, as indicated by the bioavailability number. In such cases, reaction is slower than expected, and further increase in the reaction rate does not enhance mass depletion. Mass transfer rate limitations were shown to affect both dechlorination and microbial growth kinetics. The complex dynamics between mass transfer, DNAPL transport and distribution, and

The value of magnetoencephalography for seizure-onset zone localization in magnetic resonance imaging-negative partial epilepsy.

Science.gov (United States)

Jung, Julien; Bouet, Romain; Delpuech, Claude; Ryvlin, Philippe; Isnard, Jean; Guenot, Marc; Bertrand, Olivier; Hammers, Alexander; Mauguière, François

2013-10-01

Surgical treatment of epilepsy is a challenge for patients with non-contributive brain magnetic resonance imaging. However, surgery is feasible if the seizure-onset zone is precisely delineated through intracranial electroencephalography recording. We recently described a method, volumetric imaging of epileptic spikes, to delineate the spiking volume of patients with focal epilepsy using magnetoencephalography. We postulated that the extent of the spiking volume delineated with volumetric imaging of epileptic spikes could predict the localizability of the seizure-onset zone by intracranial electroencephalography investigation and outcome of surgical treatment. Twenty-one patients with non-contributive magnetic resonance imaging findings were included. All patients underwent intracerebral electroencephalography investigation through stereotactically implanted depth electrodes (stereo-electroencephalography) and magnetoencephalography with delineation of the spiking volume using volumetric imaging of epileptic spikes. We evaluated the spatial congruence between the spiking volume determined by magnetoencephalography and the localization of the seizure-onset zone determined by stereo-electroencephalography. We also evaluated the outcome of stereo-electroencephalography and surgical treatment according to the extent of the spiking volume (focal, lateralized but non-focal or non-lateralized). For all patients, we found a spatial overlap between the seizure-onset zone and the spiking volume. For patients with a focal spiking volume, the seizure-onset zone defined by stereo-electroencephalography was clearly localized in all cases and most patients (6/7, 86%) had a good surgical outcome. Conversely, stereo-electroencephalography failed to delineate a seizure-onset zone in 57% of patients with a lateralized spiking volume, and in the two patients with bilateral spiking volume. Four of the 12 patients with non-focal spiking volumes were operated upon, none became seizure

Effects of oxygen partial pressure on Li-air battery performance

Science.gov (United States)

Kwon, Hyuk Jae; Lee, Heung Chan; Ko, Jeongsik; Jung, In Sun; Lee, Hyun Chul; Lee, Hyunpyo; Kim, Mokwon; Lee, Dong Joon; Kim, Hyunjin; Kim, Tae Young; Im, Dongmin

2017-10-01

For application in electric vehicles (EVs), the Li-air battery system needs an air intake system to supply dry oxygen at controlled concentration and feeding rate as the cathode active material. To facilitate the design of such air intake systems, we have investigated the effects of oxygen partial pressure (≤1 atm) on the performance of the Li-air cell, which has not been systematically examined. The amounts of consumed O2 and evolved CO2 from the Li-air cell are measured with a custom in situ differential electrochemical gas chromatography-mass spectrometry (DEGC-MS). The amounts of consumed O2 suggest that the oxygen partial pressure does not affect the reaction mechanism during discharge, and the two-electron reaction occurs under all test conditions. On the other hand, the charging behavior varies by the oxygen partial pressure. The highest O2 evolution ratio is attained under 70% O2, along with the lowest CO2 evolution. The cell cycle life also peaks at 70% O2 condition. Overall, an oxygen partial pressure of about 0.5-0.7 atm maximizes the Li-air cell capacity and stability at 1 atm condition. The findings here indicate that the appropriate oxygen partial pressure can be a key factor when developing practical Li-air battery systems.

Experimental and simulation analysis of hydrogen production by partial oxidation of methanol

Energy Technology Data Exchange (ETDEWEB)

Sikander, U. [National Univ. of Science and Technology, Islamabad (Pakistan)

2014-10-15

Partial oxidation of methanol is the only self-sustaining process for onboard production of hydrogen. For this a fixed bed catalytic reactor is designed, based on heterogeneous catalytic reaction. To develop an optimized process, simulation is carried out using ASPEN HYSYS v 7.1. Reaction kinetics is developed on the basis of Langmuir Hinshel wood model. 45:55:5 of CuO: ZnO: Al/sub 2/O/sub 3/ is used as a catalyst. Simulation results are studied in detail to understand the phenomenon of partial oxidation of methanol inside the reactor. An experimental rig is developed for hydrogen production through partial oxidation of methanol. Results obtained from process simulation and experimental work; are compared with each other. (author)

Partial gravity - Human impacts on facility design

Science.gov (United States)

Capps, Stephen; Moore, Nathan

1990-01-01

Partial gravity affects the body differently than earth gravity and microgravity environments. The main difference from earth gravity is human locomotion; while the main dfference from microgravity is the specific updown orientation and reach envelopes which increase volume requirements. Much data are available on earth gravity and microgravity design; however, very little information is available on human reactions to reduced gravity levels in IVA situations (without pressure suits). Therefore, if humans commit to permanent lunar habitation, much research should be conducted in the area of partial gravity effects on habitat design.

Partial oxidation of 2-propanol on perovskites

Energy Technology Data Exchange (ETDEWEB)

Sumathi, R.; Viswanathan, B.; Varadarajan, T.K. [Indian Inst. of Tech., Madras (India). Dept. of Chemistry

1998-12-31

Partial oxidation of 2-propanol was carried out on AB{sub 1-x}B`{sub x}O{sub 3} (A=Ba, B=Pb, Ce, Ti; B`=Bi, Sb and Cu) type perovskite oxides. Acetone was the major product observed on all the catalysts. All the catalysts underwent partial reduction during the reaction depending on the composition of the reactant, nature of the B site cation and the extent of substitution at B site. The catalytic activity has been correlated with the reducibility of the perovskite oxides determined from Temperature Programmed Reduction (TPR) studies. (orig.)

Development of a simultaneous partial nitrification and anaerobic ammonia oxidation process in a single reactor.

Science.gov (United States)

Cho, Sunja; Fujii, Naoki; Lee, Taeho; Okabe, Satoshi

2011-01-01

Up-flow oxygen-controlled biofilm reactors equipped with a non-woven fabric support were used as a single reactor system for autotrophic nitrogen removal based on a combined partial nitrification and anaerobic ammonium oxidation (anammox) reaction. The up-flow biofilm reactors were initiated as either a partial nitrifying reactor or an anammox reactor, respectively, and simultaneous partial nitrification and anammox was established by careful control of the aeration rate. The combined partial nitrification and anammox reaction was successfully developed in both biofilm reactors without additional biomass inoculation. The reactor initiated as the anammox reactor gave a slightly higher and more stable mean nitrogen removal rate of 0.35 (±0.19) kg-N m(-3) d(-1) than the reactor initiated as the partial nitrifying reactor (0.23 (±0.16) kg-N m(-3) d(-1)). FISH analysis revealed that the biofilm in the reactor started as the anammox reactor were composed of anammox bacteria located in inner anoxic layers that were surrounded by surface aerobic AOB layers, whereas AOB and anammox bacteria were mixed without a distinguishable niche in the biofilm in the reactor started as the partial nitrifying reactor. However, it was difficult to efficiently maintain the stable partial nitrification owing to inefficient aeration in the reactor, which is a key to development of the combined partial nitrification and anammox reaction in a single biofilm reactor. Copyright © 2010 Elsevier Ltd. All rights reserved.

Consequences of the genetic threshold model for observing partial migration under climate change scenarios.

Science.gov (United States)

Cobben, Marleen M P; van Noordwijk, Arie J

2017-10-01

Migration is a widespread phenomenon across the animal kingdom as a response to seasonality in environmental conditions. Partially migratory populations are populations that consist of both migratory and residential individuals. Such populations are very common, yet their stability has long been debated. The inheritance of migratory activity is currently best described by the threshold model of quantitative genetics. The inclusion of such a genetic threshold model for migratory behavior leads to a stable zone in time and space of partially migratory populations under a wide range of demographic parameter values, when assuming stable environmental conditions and unlimited genetic diversity. Migratory species are expected to be particularly sensitive to global warming, as arrival at the breeding grounds might be increasingly mistimed as a result of the uncoupling of long-used cues and actual environmental conditions, with decreasing reproduction as a consequence. Here, we investigate the consequences for migratory behavior and the stability of partially migratory populations under five climate change scenarios and the assumption of a genetic threshold value for migratory behavior in an individual-based model. The results show a spatially and temporally stable zone of partially migratory populations after different lengths of time in all scenarios. In the scenarios in which the species expands its range from a particular set of starting populations, the genetic diversity and location at initialization determine the species' colonization speed across the zone of partial migration and therefore across the entire landscape. Abruptly changing environmental conditions after model initialization never caused a qualitative change in phenotype distributions, or complete extinction. This suggests that climate change-induced shifts in species' ranges as well as changes in survival probabilities and reproductive success can be met with flexibility in migratory behavior at the

Design and control of the oxygen partial pressure of UO2 in TGA using the humidification system

International Nuclear Information System (INIS)

Lee, S.; Knight, T.W.; Roberts, E.

2015-01-01

Highlights: • We focus on measurement of oxygen partial pressure and change of O/M ratio under specific conditions produced by the humidification system. • This shows that the humidification system is stable, accurate, and reliable enough to be used for experiments of the oxygen partial pressure measurement for the oxide fuels. • The humidification system has benefits of easy control and flexibility for producing various oxygen partial pressures with fixed hydrogen gas flow rate. - Abstract: The oxygen to uranium (O/U) ratio of UO 2±x is determined by the oxygen content of the sample and is affected by oxygen partial pressure (pO 2 ) of the surrounding gas. Oxygen partial pressure is controllable by several methods. A common method to produce different oxygen partial pressures is the use of equilibria of different reaction gases. There are two common methods: H 2 O/H 2 reaction and CO 2 /CO reaction. In this work, H 2 O/H 2 reaction using a humidifier was employed and investigated to ensure that this humidification system for oxygen partial pressure is stable and accurate for use in Thermogravimetric Analyzer (TGA) experiments with UO 2 . This approach has the further advantage of flexibility to make a wide range of oxygen partial pressure with fixed hydrogen gas flow rate only by varying temperature of water in the humidifier. The whole system for experiments was constructed and includes the humidification system, TGA, oxygen analyzer, and gas flow controller. Uranium dioxide (UO 2 ) samples were used for experiments and oxygen partial pressure was measured at the equilibrium state of stoichiometric UO 2.0 . Oxygen partial pressures produced by humidification (wet gas) system were compared to the approach using mixed dry gases (without humidification system) to demonstrate that the humidification system provides for more stable and accurate oxygen partial pressure control. This work provides the design, method, and analysis of a humidification system for

Microstructure of Reaction Zone Formed During Diffusion Bonding of TiAl with Ni/Al Multilayer

Science.gov (United States)

Simões, Sónia; Viana, Filomena; Koçak, Mustafa; Ramos, A. Sofia; Vieira, M. Teresa; Vieira, Manuel F.

2012-05-01

In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding. TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 °C for 30 and 60 min with a pressure of 5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM), energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis reveals that zone 1 corresponds to the intermetallic Al2NiTi and AlNiTi, and zones 2 and 3 to NiAl.

Heterogeneous hyporheic zone dechlorination of a TCE groundwater plume discharging to an urban river reach.

Science.gov (United States)

Freitas, Juliana G; Rivett, Michael O; Roche, Rachel S; Durrant Neé Cleverly, Megan; Walker, Caroline; Tellam, John H

2015-02-01

The typically elevated natural attenuation capacity of riverbed-hyporheic zones is expected to decrease chlorinated hydrocarbon (CHC) groundwater plume discharges to river receptors through dechlorination reactions. The aim of this study was to assess physico-chemical processes controlling field-scale variation in riverbed-hyporheic zone dechlorination of a TCE groundwater plume discharge to an urban river reach. The 50-m long pool-riffle-glide reach of the River Tame in Birmingham (UK) studied is a heterogeneous high energy river environment. The shallow riverbed was instrumented with a detailed network of multilevel samplers. Freeze coring revealed a geologically heterogeneous and poorly sorted riverbed. A chlorine number reduction approach provided a quantitative indicator of CHC dechlorination. Three sub-reaches of contrasting behaviour were identified. Greatest dechlorination occurred in the riffle sub-reach that was characterised by hyporheic zone flows, moderate sulphate concentrations and pH, anaerobic conditions, low iron, but elevated manganese concentrations with evidence of sulphate reduction. Transient hyporheic zone flows allowing input to varying riverbed depths of organic matter are anticipated to be a key control. The glide sub-reach displayed negligible dechlorination attributed to the predominant groundwater baseflow discharge condition, absence of hyporheic zone, transition to more oxic conditions and elevated sulphate concentrations expected to locally inhibit dechlorination. The tail-of-pool-riffle sub-reach exhibited patchy dechlorination that was attributed to sub-reach complexities including significant flow bypass of a low permeability, high organic matter, silty unit of high dechlorination potential. A process-based conceptual model of reach-scale dechlorination variability was developed. Key findings of practitioner relevance were: riverbed-hyporheic zone CHC dechlorination may provide only a partial, somewhat patchy barrier to CHC

Analysis of partial and total inelasticities obtained from inclusive reactions

International Nuclear Information System (INIS)

Bellandi, J.; Covolan, R.; Costa, C.G.; Montanha, J.; Mundim, L.M.

1994-01-01

An independent analysis of model for energetic dependence on inelasticity is presented, from experimental data of pp → c X (c = π +- , Κ +- , p +- ) type inclusive reactions. 6 refs., 2 figs., 1 tab

Multi-pollutant interactions in hyporheic zones

Science.gov (United States)

Krause, S.; Weatherill, J.; Bonet, B.; Blaen, P.; Khamis, K.; Cassidy, N. J.; Hannah, D. M.; Rivett, M. O.; Lynch, I.; Ullah, S.

2017-12-01

Hyporheic zones represent hotspots of biogeochemical reactivity, with the potential to attenuate pollutants and ameliorate their impact on ecosystem functioning. Sources and types of pollutants in streambed environments are manifold, with legacy industry contaminants, agricultural pollution and emerging pollutants such as pharmaceuticals or engineered nanoparticles entering hyporheic zones along different flow paths where they mix and potentially react with each other. Current conceptualizations of drivers and controls of biogeochemical turnover in hyporheic zones highlight primarily the role of transport and reaction times but do not account for potential interactions between different pollutants. This study presents two case studies of multi-pollutant interactions to illustrate the need to consider interferences between different pollutants, their transport and reaction pathways for adequate impact assessment. We discuss in the first instance how the natural attenuation of a Trichloroethylene (TCE) groundwater plume in an agricultural catchment is limited by high riparian and hyporheic nitrate concentrations. As nitrate outcompeted TCE in its reaction with organic carbon as electron donor, TCE attenuation was in this case limited to hyporheic denitrification hotspots. Hence any pollution control measures to reduce the impact of this TCE plume require a reduction of agricultural nitrate loads, highlighting the connectedness of legacy (TCE) and more recent (nitrate) pollution problems. In the second case, we investigate how the labile organic carbon content of streambed sediments as main control of hyporheic respiration is overridden by exposure to different silver nanoparticle concentrations, representing emerging pollutants in many of our rivers. Also in this case, the impacts of different stressors (nanoparticle exposure) and drivers (availability of organic matter, water temperature) are interacting in their impacts on hyporheic zone functioning. We argue that

DEPENDENCE OF X-RAY BURST MODELS ON NUCLEAR REACTION RATES

Energy Technology Data Exchange (ETDEWEB)

Cyburt, R. H.; Keek, L.; Schatz, H. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Amthor, A. M. [Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837 (United States); Heger, A.; Meisel, Z.; Smith, K. [Joint Institute for Nuclear Astrophysics (JINA), Michigan State University, East Lansing, MI 48824 (United States); Johnson, E. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

2016-10-20

X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars, and reliable burst models are needed to interpret observations in terms of properties of the neutron star and the binary system. We investigate the dependence of X-ray burst models on uncertainties in (p, γ ), ( α , γ ), and ( α , p) nuclear reaction rates using fully self-consistent burst models that account for the feedbacks between changes in nuclear energy generation and changes in astrophysical conditions. A two-step approach first identified sensitive nuclear reaction rates in a single-zone model with ignition conditions chosen to match calculations with a state-of-the-art 1D multi-zone model based on the Kepler stellar evolution code. All relevant reaction rates on neutron-deficient isotopes up to mass 106 were individually varied by a factor of 100 up and down. Calculations of the 84 changes in reaction rate with the highest impact were then repeated in the 1D multi-zone model. We find a number of uncertain reaction rates that affect predictions of light curves and burst ashes significantly. The results provide insights into the nuclear processes that shape observables from X-ray bursts, and guidance for future nuclear physics work to reduce nuclear uncertainties in X-ray burst models.

Dimensionless model to determine spontaneous combustion danger zone in the longwall gob

Institute of Scientific and Technical Information of China (English)

ZHANG Xin-hai; DENG Jun; WEN Hu

2011-01-01

According to spontaneous combustion propensity,the longwall gob is divided into three zones,including heat dissipation zone,self-heating zone and the choking zone.Only in the self-heating zone can temperature of coal rise due to oxidation.Studying the distribution of the “Three Zones” in gob is important for predicting and preventing spontaneous combustion in coalmine.In normal mining operations,temperature of coal is roughly constant.The process of mass transfer in the gob is considered to be steady.Based on mass conservation,gas species conservation,darcy' s law,Ficks law of diffusion and coal oxidation 1-grade reaction rule,governing equation for air leakage intensity and species concentration are deduced.With critical value of coal spontaneous combustion and the size of longwall workface as basic dimension,a dimensionless steady coupled model of air flow diffusion and chemical reaction in loose coal of Fully Mechanized Top-Coal Caving Mining Workface (FMTCCMW) is setup.By solving the model numerically,regulation of three zones' distribution and spontaneous combustion in the gob can be obtained.The results can be easily popularized to prediction of spontaneous combustion in other coalmines' longwall gob.

Capillary zone electrophoresis-multiple reaction monitoring from 100 pg of RAW 264.7 cell lysate digest.

Science.gov (United States)

Sun, Liangliang; Li, Yihan; Champion, Matthew M; Zhu, Guijie; Wojcik, Roza; Dovichi, Norman J

2013-06-07

Capillary zone electrophoresis-multiple/single reaction monitoring (CZE-MRM/SRM), which employed an electrokinetically driven sheath-flow electrospray interface, was used for the rapid and highly sensitive detection of protein analytes in complex tryptic digests. MRM channels were developed against a commercial exponential mixture of bovine proteins. Five proteins spanning four orders of magnitude concentration range were confidently detected from only 2.5 ng of the digest mixture; the mass detection limits (S/N = 3) of two detected proteins, alpha-casein and glutamate dehydrogenase were about 600 zmol and 30 amol, respectively. This technique was then applied to a RAW 264.7 cell lysate digest. Three proteins were confidently and reproducibly detected from 100 pg of this digest. The sample amount corresponds to the approximate protein content from a single cell, which suggests that CZE-MRM may be a useful analytical tool in chemical cytometry. In addition to providing highly sensitive detection of proteins in complex mixtures, this system is highly rapid; migration time of the protein digests was less than 10 min.

Oxygen binding to partially nitrosylated hemoglobin.

Science.gov (United States)

Fago, Angela; Crumbliss, Alvin L; Hendrich, Michael P; Pearce, Linda L; Peterson, Jim; Henkens, Robert; Bonaventura, Celia

2013-09-01

Reactions of nitric oxide (NO) with hemoglobin (Hb) are important elements in protection against nitrosative damage. NO in the vasculature is depleted by the oxidative reaction with oxy Hb or by binding to deoxy Hb to generate partially nitrosylated Hb (Hb-NO). Many aspects of the formation and persistence of Hb-NO are yet to be clarified. In this study, we used a combination of EPR and visible absorption spectroscopy to investigate the interactions of partially nitrosylated Hb with O2. Partially nitrosylated Hb samples had predominantly hexacoordinate NO-heme geometry and resisted oxidation when exposed to O2 in the absence of anionic allosteric effectors. Faster oxidation occurred in the presence of 2,3-diphosphoglycerate (DPG) or inositol hexaphosphate (IHP), where the NO-heme derivatives had higher levels of pentacoordinate heme geometry. The anion-dependence of the NO-heme geometry also affected O2 binding equilibria. O2-binding curves of partially nitrosylated Hb in the absence of anions were left-shifted at low saturations, indicating destabilization of the low O2 affinity T-state of the Hb by increasing percentages of NO-heme, much as occurs with increasing levels of CO-heme. Samples containing IHP showed small decreases in O2 affinity, indicating shifts toward the low-affinity T-state and formation of inert α-NO/β-met tetramers. Most remarkably, O2-equilibria in the presence of the physiological effector DPG were essentially unchanged by up to 30% NO-heme in the samples. As will be discussed, under physiological conditions the interactions of Hb with NO provide protection against nitrosative damage without impairing O2 transport by Hb's unoccupied heme sites. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins. Copyright © 2013 Elsevier B.V. All rights reserved.

Reductive dechlorination of trichloroethene DNAPL source zones: source zone architecture versus electron donor availability

Science.gov (United States)

Krol, M.; Kokkinaki, A.; Sleep, B.

2014-12-01

The persistence of dense-non-aqueous-phase liquids (DNAPLs) in the subsurface has led practitioners and regulatory agencies to turn towards low-maintenance, low-cost remediation methods. Biological degradation has been suggested as a possible solution, based on the well-proven ability of certain microbial species to break down dissolved chlorinated ethenes under favorable conditions. However, the biodegradation of pure phase chlorinated ethenes is subject to additional constraints: the continuous release of electron acceptor at a rate governed by mass transfer kinetics, and the temporal and spatial heterogeneity of DNAPL source zones which leads to spatially and temporally variable availability of the reactants for reductive dechlorination. In this work, we investigate the relationship between various DNAPL source zone characteristics and reaction kinetics using COMPSIM, a multiphase groundwater model that considers non-equilibrium mass transfer and Monod-type kinetics for reductive dechlorination. Numerical simulations are performed for simple, homogeneous trichloroethene DNAPL source zones to demonstrate the effect of single source zone characteristics, as well as for larger, more realistic heterogeneous source zones. It is shown that source zone size, and mass transfer kinetics may have a decisive effect on the predicted bio-enhancement. Finally, we evaluate the performance of DNAPL bioremediation for realistic, thermodynamically constrained, concentrations of electron donor. Our results indicate that the latter may be the most important limitation for the success of DNAPL bioremediation, leading to reduced bio-enhancement and, in many cases, comparable performance with water flooding.

Laboratory investigations of the effects of nitrification-induced acidification on Cr cycling in vadose zone material partially derived from ultramafic rocks

Science.gov (United States)

Mills, Christopher T.; Goldhaber, Martin B.

2012-01-01

Sacramento Valley (California, USA) soils and sediments have high concentrations of Cr(III) because they are partially derived from ultramafic material. Some Cr(III) is oxidized to more toxic and mobile Cr(VI) by soil Mn oxides. Valley soils typically have neutral to alkaline pH at which Cr(III) is highly immobile. Much of the valley is under cultivation and is both fertilized and irrigated. A series of laboratory incubation experiments were conducted to assess how cultivation might impact Cr cycling in shallow vadose zone material from the valley. The first experiments employed low (7.1 mmol N per kg soil) and high (35 mmol N kg− 1) concentrations of applied (NH4)2SO4. Initially, Cr(VI) concentrations were up to 45 and 60% greater than controls in low and high incubations, respectively. After microbially-mediated oxidation of all NH4+, Cr(VI) concentrations dropped below control values. Increased nitrifying bacterial populations (estimated by measurement of phospholipid fatty acids) may have increased the Cr(VI) reduction capacity of the vadose zone material resulting in the observed decreases in Cr(VI). Another series of incubations employed vadose zone material from a different location to which low (45 meq kg− 1) and high (128 meq kg− 1) amounts of NH4Cl, KCl, and CaCl2 were applied. All treatments, except high concentration KCl, resulted in mean soil Cr(VI) concentrations that were greater than the control. High concentrations of water-leachable Ba2 + (mean 38 μmol kg− 1) in this treatment may have limited Cr(VI) solubility. A final set of incubations were amended with low (7.1 mmol N kg− 1) and high (35 mmol N kg− 1) concentrations of commercial liquid ammonium polyphosphate (APP) fertilizer which contained high concentrations of Cr(III). Soil Cr(VI) in the low APP incubations increased to a concentration of 1.8 μmol kg− 1 (5 × control) over 109 days suggesting that Cr(III) added with the APP fertilizer was more

Simultaneous hydrogen and methanol enhancement through a recuperative two-zone thermally coupled membrane reactor

Energy Technology Data Exchange (ETDEWEB)

Bayat, M. [Shiraz University, Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz (Iran, Islamic Republic of); Rahimpour, M.R. [Shiraz University, Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz (Iran, Islamic Republic of); Shiraz University, Gas Center of Excellence, Shiraz (Iran, Islamic Republic of)

2012-12-15

In this work, a novel configuration with two zones instead of one single integrated catalytic bed in thermally coupled membrane reactor (TCMR) is developed for enhancement of simultaneous methanol, benzene and hydrogen production. In the first zone, the synthesis gas is partly converted to methanol in a conventional water-cooled reactor. In the second zone, the reaction heat is used to drive the endothermic dehydrogenation of cyclohexane reaction in second tube side. Selective permeation of hydrogen through the Pd-Ag membrane is achieved by co-current flow of sweep gas through the permeation side. The length of first zone is chosen equal 35 cm which the optimization procedure obtained this value. The proposed model has been used to compare the performance of a two-zone thermally coupled membrane reactor (TZTCMR) with conventional reactor (CR) and TCMR at identical process conditions. The simulation results represent 13.14 % enhancement in the production of pure hydrogen in comparison with TCMR. Moreover, 2.96 and 4.54 % enhancement of the methanol productivity relative to TCMR and CR were seen, respectively, owing to utilizing higher temperature at the first parts of reactor for higher reaction rate and then reducing temperature gradually at the end parts of reactor for increasing thermodynamics equilibrium conversion in TZTCMR. (orig.)

Reaction rate of 24Mg(p,γ)25Al

International Nuclear Information System (INIS)

Powell, D.C.; Iliadis, C.; Champagne, A.E.; Grossmann, C.A.; Hale, S.E.; Hansper, V.Y.; McLean, L.K.

1999-01-01

The proton-capture reaction on 24 Mg has been investigated in the bombarding energy range of E p =0.2-1.7 MeV. Resonance properties (strengths, branching ratios and lifetimes) of low-energy resonances have been measured. From the experimental results, accurate proton partial widths, γ-ray partial widths and total widths (Γ p , Γ γ , and Γ) have been deduced. The present experimental information establishes the 24 Mg+p reaction rates over the temperature range T=0.02-2.0 GK with statistical uncertainties of 5% to 21%. Our recommended reaction rates deviate from previous estimates by 18% to 45%. Based on our results, we can rule out the recent suggestion that the total width of the E R =223 keV resonance has a significant influence on the reaction rates. We also discuss several effects that might give rise to systematic uncertainties in the reaction rates. The astrophysical implications for hydrogen burning of 24 Mg at low stellar temperatures are presented

Transformation-Dissolution Reactions Partially Explain Adverse Effects of Metallic Silver Nanoparticles to Soil Nitrification in Different Soils.

Science.gov (United States)

Bollyn, Jessica; Willaert, Bernd; Kerré, Bart; Moens, Claudia; Arijs, Katrien; Mertens, Jelle; Leverett, Dean; Oorts, Koen; Smolders, Erik

2018-04-25

Risk assessment of metallic nanoparticles (NP) is critically affected by the concern that toxicity goes beyond that of the metallic ion. This study addressed this concern for soils with silver (Ag)-NP using the Ag-sensitive nitrification assay. Three agricultural soils (A,B,C) were spiked with equivalent Ag doses of either Ag-NP (d = 13 nm) or AgNO 3 . Soil solution was isolated and monitored over 97 days with due attention to accurate Ag fractionation at low (∼10 µg L -1 ) Ag concentrations. Truly dissolved (soils decreased with reaction half-lives of 4 to 22 days depending on the soil, denoting important Ag-ageing reactions. In contrast, truly dissolved Ag in Ag-NP-amended soils first increased by dissolution and subsequently decreased by ageing; the concentration never exceeding that in the AgNO 3 -amended soils. The half-lives of Ag-NP transformation-dissolution were about 4 days (soils A&B) and 36 days (soil C). The Ag toxic thresholds (EC10, mg Ag kg -1 soil) of nitrification, either evaluated at 21 or 35 days after spiking, were similar between the two Ag forms (soils A&B) but were factors 3 to 8 lower for AgNO 3 than for Ag-NP (soil C), largely corroborating with dissolution differences. This fate and bio-assay showed that Ag-NPs are not more toxic than AgNO 3 at equivalent total soil Ag concentrations and that differences in Ag-dissolution at least partially explain toxicity differences between the forms and among soils. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Three key points along an intrinsic reaction coordinate

Indian Academy of Sciences (India)

Unknown

Abstract. The concept of the reaction force is presented and discussed in detail. For typical processes with energy barriers, it has a universal form which defines three key points along an intrinsic reaction co- ordinate: the force minimum, zero and maximum. We suggest that the resulting four zones be interpreted as involving ...

Enhanced performance of solid oxide electrolysis cells by integration with a partial oxidation reactor: Energy and exergy analyses

International Nuclear Information System (INIS)

Visitdumrongkul, Nuttawut; Tippawan, Phanicha; Authayanun, Suthida; Assabumrungrat, Suttichai; Arpornwichanop, Amornchai

2016-01-01

Highlights: • Process design of solid oxide electrolyzer integrated with a partial oxidation reactor is studied. • Effect of key operating parameters of partial oxidation reactor on the electrolyzer performance is presented. • Exergy analysis of the electrolyzer process is performed. • Partial oxidation reactor can enhance the solid oxide electrolyzer performance. • Partial oxidation reactor in the process is the highest exergy destruction unit. - Abstract: Hydrogen production without carbon dioxide emission has received a large amount of attention recently. A solid oxide electrolysis cell (SOEC) can produce pure hydrogen and oxygen via a steam electrolysis reaction that does not emit greenhouse gases. Due to the high operating temperature of SOEC, an external heat source is required for operation, which also helps to improve SOEC performance and reduce operating electricity. The non-catalytic partial oxidation reaction (POX), which is a highly exothermic reaction, can be used as an external heat source and can be integrated with SOEC. Therefore, the aim of this work is to study the effect of operating parameters of non-catalytic POX (i.e., the oxygen to carbon ratio, operating temperature and pressure) on SOEC performance, including exergy analysis of the process. The study indicates that non-catalytic partial oxidation can enhance the hydrogen production rate and efficiency of the system. In terms of exergy analysis, the non-catalytic partial oxidation reactor is demonstrated to be the highest exergy destruction unit due to irreversible chemical reactions taking place, whereas SOEC is a low exergy destruction unit. This result indicates that the partial oxidation reactor should be improved and optimally designed to obtain a high energy and exergy system efficiency.

[Partial response of solar urticaria to omalizumab therapy].

Science.gov (United States)

Kowalzick, L; Thiel, W; C Bielfeld; Ziegler, H; Eickenscheidt, L

2017-06-01

The treatment of solar urticaria is regarded as difficult. In some cases good responses to the anti-IgE antibody omalizumab (Xolair®), approved for treatment of chronic spontaneous urticaria, have been reported. We report on a 50-year-old Caucasian woman who for the last 5 years has developed localized itching and stinging erythemas following exposure to sunlight accompanied sometimes by anaphylactic reactions. Oral antihistamines in three- to four-fold doses and a topical sun screen had been only partially effective in long-term use. Positive immediate-type reactions with whealing appeared in phototesting with low doses of UVB and UVA. Three weeks after s. c. injection of 300 mg omalizumab, the minimal urticarial dose (MUD) for UVB was increased at least 20-fold (from omalizumab administration to 14 points in weeks two and three. Overall, a partial response of solar urticaria to omalizumab therapy could be observed in the present case.

Effect of Regulated Deficit Irrigation (RDI and Partial Root zone Drying (PRD on Quantitative and Qualitative Traits of Strawberry

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A. Shahnazari

2016-02-01

Full Text Available Introduction: Deficit irrigation (DI is a suitable solution to gain acceptable and economic performance by using minimum amount of water. The partial root zone drying (PRD method introduced in Australia for the first time and its goal was controlling the vine’s excessive growth. This goal gained by alternative drying the rootzone. Basically the theory of PRD method, is expanding the plant’s roots by applying alternative stress on different sides of the roots. So the plants with PRD irrigation method can have different root system in comparison with other irrigation methods. At this method the plant’s condition would be OK by uptaking water from wet side, and the roots at the dry side can release abscisic acid hormone which decrease the stomatal conductance and consequently the water use efficiency would be increase.There had been studies on the effect of water tension on strawberry. The previous studies on strawberry indicated that the water stress can increase the plant’s brix concentration and some of plant acids.The awareness of the impact of water deficit stress on strawberry plant quantity and quality is essential for irrigation and product management, and at the current study, effect of different deficit irrigation methods on quantitative and qualitative traits of strawberry have been evaluated. The focus at the current study was on the qualitative traits. Materials and Methods: The present study was conducted in one of strawberry farms of Babolsar city in 2012 to evaluate the effects of deficit irrigation and partial root zone drying on quantitative and qualitative traits of strawberry plants. Three Irrigation treatments were studied: Full Irrigation (FI, Regulated Deficit Irrigation (RDI75% at 75% level of plants water requirementand Partial Root zone Drying (PRD75% at 75% level of plants water requirement. The study was conducted in a randomized complete block design with three replications. Irrigation was continued until the

Patient satisfaction with single-tooth implant therapy in the esthetic zone

NARCIS (Netherlands)

den Hartog, Laurens; Meijer, Henny J. A.; Santing, Hendrik J.; Vissink, Arjan; Raghoebar, Gerry M.

2014-01-01

This prospective study assessed patient satisfaction before and after single-tooth implant therapy in the esthetic zone. Before implant therapy, patients wore an acrylic resin tissue-supported removable partial denture (RPD). A total of 153 patients were included. Self-administered questionnaires

DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

Science.gov (United States)

Bradner, H.; Gordon, H.S.

1957-12-24

A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

Melt migration modeling in partially molten upper mantle

Science.gov (United States)

Ghods, Abdolreza

The objective of this thesis is to investigate the importance of melt migration in shaping major characteristics of geological features associated with the partial melting of the upper mantle, such as sea-floor spreading, continental flood basalts and rifting. The partial melting produces permeable partially molten rocks and a buoyant low viscosity melt. Melt migrates through the partially molten rocks, and transfers mass and heat. Due to its much faster velocity and appreciable buoyancy, melt migration has the potential to modify dynamics of the upwelling partially molten plumes. I develop a 2-D, two-phase flow model and apply it to investigate effects of melt migration on the dynamics and melt generation of upwelling mantle plumes and focusing of melt migration beneath mid-ocean ridges. Melt migration changes distribution of the melt-retention buoyancy force and therefore affects the dynamics of the upwelling plume. This is investigated by modeling a plume with a constant initial melt of 10% where no further melting is considered. Melt migration polarizes melt-retention buoyancy force into high and low melt fraction regions at the top and bottom portions of the plume and therefore results in formation of a more slender and faster upwelling plume. Allowing the plume to melt as it ascends through the upper mantle also produces a slender and faster plume. It is shown that melt produced by decompressional melting of the plume migrates to the upper horizons of the plume, increases the upwelling velocity and thus, the volume of melt generated by the plume. Melt migration produces a plume which lacks the mushroom shape observed for the plume models without melt migration. Melt migration forms a high melt fraction layer beneath the sloping base of the impermeable oceanic lithosphere. Using realistic conditions of melting, freezing and melt extraction, I examine whether the high melt fraction layer is able to focus melt from a wide partial melting zone to a narrow region

The thermochemical, two-phase dynamics of subduction zones: results from new, fully coupled models

Science.gov (United States)

Rees Jones, D. W.; Katz, R. F.; May, D.; Tian, M.; Rudge, J. F.

2017-12-01

Subduction zones are responsible for most of Earth's subaerial volcanism. However, previous geodynamic modelling of subduction zones has largely neglected magmatism. We previously showed that magmatism has a significant thermal impact, by advecting sensible heat into the lithosphere beneath arc volcanos [1]. Inclusion of this effect helps reconcile subduction zone models with petrological and heat flow observations. Many important questions remain, including how magma-mantle dynamics of subduction zones affects the position of arc volcanos and the character of their lavas. In this presentation, we employ a fully coupled, thermochemical, two-phase flow theory to investigate the dynamics of subduction zones. We present the first results from our new software (SubFUSc), which solves the coupled equations governing conservation of mass, momentum, energy and chemical species. The presence and migration of partial melts affect permeability and mantle viscosity (both directly and through their thermal impact); these, in turn, feed back on the magma-mantle flow. Thus our fully coupled modelling improves upon previous two-phase models that decoupled the governing equations and fixed the thermal structure [2]. To capture phase change, we use a novel, simplified model of the mantle melting in the presence of volatile species. As in the natural system, volatiles are associated with low-degree melting at temperatures beneath the anhydrous solidus; dehydration reactions in the slab supply volatiles into the wedge, triggering silicic melting. We simulate the migration of melts under buoyancy forces and dynamic pressure gradients. We thereby demonstrate the dynamical controls on the pattern of subduction-zone volcanism (particularly its location, magnitude, and chemical composition). We build on our previous study of the thermal consequences of magma genesis and segregation. We address the question of what controls the location of arc volcanoes themselves [3]. [1] Rees Jones, D. W

Reaction diffusion equations with boundary degeneracy

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Huashui Zhan

2016-03-01

Full Text Available In this article, we consider the reaction diffusion equation $$ \\frac{\\partial u}{\\partial t} = \\Delta A(u,\\quad (x,t\\in \\Omega \\times (0,T, $$ with the homogeneous boundary condition. Inspired by the Fichera-Oleinik theory, if the equation is not only strongly degenerate in the interior of $\\Omega$, but also degenerate on the boundary, we show that the solution of the equation is free from any limitation of the boundary condition.

Partial Cross Sections of Neutron-Induced Reactions on nCu at En = 6, 8, 10, 12, 14, and 16 MeV for 0νββ Background Studies

Science.gov (United States)

Gooden, M. E.; Fallin, B. A.; Finch, S. W.; Kelley, J. H.; Howell, C. R.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Stanislav, V.

2014-05-01

Partial cross-section measurements of (n,n'γ) reactions on natCu were carried out at TUNL using monoenergetic neutrons at six energies of En = 6, 8, 10, 12, 14, 16 MeV. These studies were performed to provide accurate cross-section data on materials abundant in experimental setups involving HPGe detectors used to search for rare events, like the neutrino-less double-beta decay of 76Ge. Spallation and (α,n) neutrons are expected to cause the largest source of external background in the energy region of interest. At TUNL pulsed neutron beams were produced via the 2H(d,n)3He reaction and the deexcitation γ rays from the reaction natCu(n,xγ) were detected with clover HPGe detectors. Cross-section results for the strongest transtions in 63Cu and 65Cu will be reported, and will compared to model calculations and to data recently obtained at LANL with a white neutron beam.

The real value of nuclear-weapon-free zones

International Nuclear Information System (INIS)

Carasales, J.

1998-01-01

The international community has greeted the establishment of two new nuclear weapon-free zones with praise. Africa and South Asia are the regions which will join, once the respective treaties are ratified and in force, Latin America and the South Pacific to ensure that extensive areas of the earth remain free of nuclear weapons. The usual reaction to these accomplishments is to hail them as important contributions to international peace and security, and as meaningful steps towards a world free of nuclear weapons. The nuclear weapon-free zones have their value but this value relates mainly to the countries within the zone. The interest of nuclear-weapon states are not really affected, or, if they are, the influence is not significant. One should bear in mind that the really important and meaningful nuclear weapon-free zones have yet to be achieved

Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance

Science.gov (United States)

Harvey, Judson W.; Fuller, Christopher C.

1998-01-01

We determined the role of the hyporheic zone (the subsurface zone where stream water and shallow groundwater mix) in enhancing microbially mediated oxidation of dissolved manganese (to form manganese precipitates) in a drainage basin contaminated by copper mining. The fate of manganese is of overall importance to water quality in Pinal Creek Basin, Arizona, because manganese reactions affect the transport of trace metals. The basin-scale role of the hyporheic zone is difficult to quantify because stream-tracer studies do not always reliably characterize the cumulative effects of the hyporheic zone. This study determined cumulative effects of hyporheic reactions in Pinal Creek basin by characterizing manganese uptake at several spatial scales (stream-reach scale, hyporheic-flow-path scale, and sediment-grain scale). At the stream-reach scale a one-dimensional stream-transport model (including storage zones to represent hyporheic flow paths) was used to determine a reach-averaged time constant for manganese uptake in hyporheic zones, 1/λs, of 1.3 hours, which was somewhat faster but still similar to manganese uptake time constants that were measured directly in centimeter-scale hyporheic flow paths (1/λh= 2.6 hours), and in laboratory batch experiments using streambed sediment (1/λ = 2.7 hours). The modeled depths of subsurface storage zones (ds = 4–17 cm) and modeled residence times of water in storage zones (ts = 3–12 min) were both consistent with direct measurements in hyporheic flow paths (dh = 0–15 cm, th = 1–25 min). There was also good agreement between reach-scale modeling and direct measurements of the percentage removal of dissolved manganese in hyporheic flow paths (fs = 8.9%, andfh = 9.3%rpar;. Manganese uptake experiments in the laboratory using sediment from Pinal Creek demonstrated (through comparison of poisoned and unpoisoned treatments) that the manganese removal process was enhanced by microbially mediated oxidation. The

Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes.

Science.gov (United States)

Guan, Zixuan; Chen, Di; Chueh, William C

2017-08-30

The oxygen incorporation reaction, which involves the transformation of an oxygen gas molecule to two lattice oxygen ions in a mixed ionic and electronic conducting solid, is a ubiquitous and fundamental reaction in solid-state electrochemistry. To understand the reaction pathway and to identify the rate-determining step, near-equilibrium measurements have been employed to quantify the exchange coefficients as a function of oxygen partial pressure and temperature. However, because the exchange coefficient contains contributions from both forward and reverse reaction rate constants and depends on both oxygen partial pressure and oxygen fugacity in the solid, unique and definitive mechanistic assessment has been challenging. In this work, we derive a current density equation as a function of both oxygen partial pressure and overpotential, and consider both near and far from equilibrium limits. Rather than considering specific reaction pathways, we generalize the multi-step oxygen incorporation reaction into the rate-determining step, preceding and following quasi-equilibrium steps, and consider the number of oxygen ions and electrons involved in each. By evaluating the dependence of current density on oxygen partial pressure and overpotential separately, one obtains the reaction orders for oxygen gas molecules and for solid-state species in the electrode. We simulated the oxygen incorporation current density-overpotential curves for praseodymium-doped ceria for various candidate rate-determining steps. This work highlights a promising method for studying the exchange kinetics far away from equilibrium.

Reaction behavior of SO2 in the sintering process with flue gas recirculation.

Science.gov (United States)

Yu, Zhi-Yuan; Fan, Xiao-Hui; Gan, Min; Chen, Xu-Ling; Chen, Qiang; Huang, Yun-Song

2016-07-01

The primary goal of this paper is to reveal the reaction behavior of SO2 in the sinter zone, combustion zone, drying-preheating zone, and over-wet zone during flue gas recirculation (FGR) technique. The results showed that SO2 retention in the sinter zone was associated with free-CaO in the form of CaSO3/CaSO4, and the SO2 adsorption reached a maximum under 900ºC. SO2 in the flue gas came almost from the combustion zone. One reaction behavior was the oxidation of sulfur in the sintering mix when the temperature was between 800 and 1000ºC; the other behavior was the decomposition of sulfite/sulfate when the temperature was over 1000ºC. However, the SO2 adsorption in the sintering bed mainly occurred in the drying-preheating zone, adsorbed by CaCO3, Ca(OH)2, and CaO. When the SO2 adsorption reaction in the drying-preheating zone reached equilibrium, the excess SO2 gas continued to migrate to the over-wet zone and was then absorbed by Ca(OH)2 and H2O. The emission rising point of SO2 moved forward in combustion zone, and the concentration of SO2 emissions significantly increased in the case of flue gas recirculation (FGR) technique. Aiming for the reuse of the sensible heat and a reduction in exhaust gas emission, the FGR technique is proposed in the iron ore sintering process. When using the FGR technique, SO2 emission in exhaust gas gets changed. In practice, the application of the FGR technique in a sinter plant should be cooperative with the flue gas desulfurization (FGD) technique. Thus, it is necessary to study the influence of the FGR technique on SO2 emissions because it will directly influence the demand and design of the FGD system.

Characterising Complex Enzyme Reaction Data.

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Handan Melike Dönertaş

Full Text Available The relationship between enzyme-catalysed reactions and the Enzyme Commission (EC number, the widely accepted classification scheme used to characterise enzyme activity, is complex and with the rapid increase in our knowledge of the reactions catalysed by enzymes needs revisiting. We present a manual and computational analysis to investigate this complexity and found that almost one-third of all known EC numbers are linked to more than one reaction in the secondary reaction databases (e.g., KEGG. Although this complexity is often resolved by defining generic, alternative and partial reactions, we have also found individual EC numbers with more than one reaction catalysing different types of bond changes. This analysis adds a new dimension to our understanding of enzyme function and might be useful for the accurate annotation of the function of enzymes and to study the changes in enzyme function during evolution.

Partial Reduction of Esters to Aldehydes Using a Novel Modified Red-Al Reducing Agent

Energy Technology Data Exchange (ETDEWEB)

Shin, Won Kyu; Kang, Daehoon; An, Duk Keun [Kangwon National Univ., Chunchon (Korea, Republic of)

2014-07-15

We have developed a convenient alternative method for the synthesis of aldehydes from both aromatic and aliphatic esters in very good to excellent yields in the absence of any additives using a modified Red-Al that was easily prepared by reacting commercially available Red-Al with cis-2,6-dimethyl morpholine. The advantages of the present methodology are as follows: simple preparation procedure of the reducing agent, improved product yields, convenient reaction temperature, and short reaction times. Therefore, the new reagent has great potential to be a useful alternative partial reducing agent for the synthesis of aldehydes from esters in organic synthesis. Aldehydes are valuable building blocks and reactive intermediates in organic synthesis. The general and classical syntheses of aldehydes from esters involve reduction-oxidation and partial reduction using efficient partial reducing agents. Obviously, one-step partial reduction methods are more useful than two-step reduction-oxidation methods owing to their simplicity, and generality in organic synthesis.

Tantrums, Emotion Reactions and Their EEG Correlates in Childhood Benign Rolandic Epilepsy vs. Complex Partial Seizures: Exploratory Observations.

Science.gov (United States)

Potegal, Michael; Drewel, Elena H; MacDonald, John T

2018-01-01

We explored associations between EEG pathophysiology and emotional/behavioral (E/B) problems of children with two types of epilepsy using standard parent questionnaires and two new indicators: tantrums recorded by parents at home and brief, emotion-eliciting situations in the laboratory. Children with Benign Rolandic epilepsy (BRE, N = 6) reportedly had shorter, more angry tantrums from which they recovered quickly. Children with Complex Partial Seizures (CPS, N = 13) had longer, sadder tantrums often followed by bad moods. More generally, BRE correlated with anger and aggression; CPS with sadness and withdrawal. Scores of a composite group of siblings ( N = 11) were generally intermediate between the BRE and CPS groups. Across all children, high voltage theta and/or interictal epileptiform discharges (IEDs) correlated with negative emotional reactions. Such EEG abnormalities in left hemisphere correlated with greater social fear, right hemisphere EEG abnormalities with greater anger. Right hemisphere localization in CPS was also associated with parent-reported problems at home. If epilepsy alters neural circuitry thereby increasing negative emotions, additional assessment of anti-epileptic drug treatment of epilepsy-related E/B problems would be warranted.

Role of the unsaturated zone in radioactive and hazardous waste disposal

International Nuclear Information System (INIS)

Mercer, J.W.; Marine, I.W.; Rao, P.S.C.

1983-01-01

The problems of hazardous and low-level radioactive waste disposal caused by the physical and chemical processes active in the unsaturated zone are explored in this book. The focus is on the use of laboratory analyses, field observations, and numerical and analytical calculations to create a clear picture of both problems and potential solutions. Topics include policy modeling, statistical techniques, liners, and field applications. Contents include: Modeling of Moisture Movement through Layered Trench Covers; Role of Partially Saturated Soil in Liner Design for Hazardous Waste Disposal Sites; Field Experiments to Determine Saturated Hydraulic Conductivity in the Vadose Zone; Role of Desaturation on Transport through Fractured Rock; Nuclear Waste Isolation in the Unsaturated Zone of Arid Regions

Physiological reactions in goat breeds maintained under shade, sun and partially shaded areas

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Luís Fernando Dias Medeiros

2015-12-01

Full Text Available ABSTRACT. Medeiros L.F.D., Rodrigues V.C., Vieira D.H., Souza S.L.G. de, Neto O.C., Figueiredo N. de, Pinto C.F.D., Miranda A.L. & Violento C.B. [Physiological reactions in goat breeds maintained under shade, sun and partially shaded areas.] Reações fisiológicas de cabras em diferentes ambientes e coeficiente de tolerância ao calor em cabritos. Revista Brasileira de Medicina Veterinária, 37(4:286-296, 2015. Departamento de Reprodução e Avaliação Animal, Instituto de Zootecnia, Universidade Federal Rural do Rio de Janeiro, BR 465 Km 7, Seropédica, RJ 23851-970, Brasil. E-mail: diasmedeiros@yahoo.com.br The experiment was carried out to measure the effects of thermal stress on the rectal temperature (RT and respiratory frequency (RF, in animals of Boer and Saanen breeds, under the conditions of hot and humid climate of city of Rio de Janeiro, Baixada Fluminense, South East Region of Brazil; also the heat tolerance coefficient (HTC of Amakiri e Funcho was applied on pure and crossbreeds kids. The goats were divided into three groups, each group consisting of four females from each breed group. Each group was subjected to different surroundings, constituted by three experimental treatment: treatment A, with a sun protected enclosed area; treatment B, a sun exposed area without covering; and treatment C, area with a 50% covered section and a 50% sun exposed area, which permitted free circulation of the goats. A Balanced Latin Square was used. The RT and RF of the goats, in the afternoon periods (l5h00, were higher, than in the morning periods (09h00. The animals kept in the sun presented much higher results, especially in the afternoon periods, than the animals in the other two confinement areas. There were no differences in the RT and RF of the groups maintained in the shade or in partially covered area. There were differences in the RT and RF measurements between the two breeds, in the morning periods and in the afternoon periods

Correlation of psychomotor findings and the ability to partially weight bear

Science.gov (United States)

2012-01-01

Background Partial weight bearing is thought to avoid excessive loading that may interfere with the healing process after surgery of the pelvis or the lower extremity. The object of this study was to investigate the relationship between the ability to partially weight bear and the patient's psychomotor skills and an additional evaluation of the possibility to predict this ability with a standardized psychomotor test. Methods 50 patients with a prescribed partial weight bearing at a target load of 15 kg following surgery were verbally instructed by a physical therapist. After the instruction and sufficient training with the physical therapist vertical ground reaction forces using matrix insoles were measured while walking with forearm crutches. Additionally, psychomotor skills were tested with the Motorische Leistungsserie (MLS). To test for correlations Spearman's Rank correlation was used. For further comparison of the two groups a Mann-Withney test was performed using Bonferroni correction. Results The patient's age and body weight significantly correlated with the ability to partially weight bear at a 15 kg target load. There were significant correlations between several subtests of the MLS and ground reaction forces measured while walking with crutches. Patients that were able to correctly perform partial weight bearing showed significant better psychomotor skills especially for those subtests where both hands had to be coordinated simultaneously. Conclusions The ability to partially weight bear is associated with psychomotor skills. The MLS seems to be a tool that helps predicting the ability to keep within the prescribed load limits. PMID:22330655

Correlation of psychomotor findings and the ability to partially weight bear

Directory of Open Access Journals (Sweden)

Ruckstuhl Thomas

2012-02-01

Full Text Available Abstract Background Partial weight bearing is thought to avoid excessive loading that may interfere with the healing process after surgery of the pelvis or the lower extremity. The object of this study was to investigate the relationship between the ability to partially weight bear and the patient's psychomotor skills and an additional evaluation of the possibility to predict this ability with a standardized psychomotor test. Methods 50 patients with a prescribed partial weight bearing at a target load of 15 kg following surgery were verbally instructed by a physical therapist. After the instruction and sufficient training with the physical therapist vertical ground reaction forces using matrix insoles were measured while walking with forearm crutches. Additionally, psychomotor skills were tested with the Motorische Leistungsserie (MLS. To test for correlations Spearman's Rank correlation was used. For further comparison of the two groups a Mann-Withney test was performed using Bonferroni correction. Results The patient's age and body weight significantly correlated with the ability to partially weight bear at a 15 kg target load. There were significant correlations between several subtests of the MLS and ground reaction forces measured while walking with crutches. Patients that were able to correctly perform partial weight bearing showed significant better psychomotor skills especially for those subtests where both hands had to be coordinated simultaneously. Conclusions The ability to partially weight bear is associated with psychomotor skills. The MLS seems to be a tool that helps predicting the ability to keep within the prescribed load limits.

Direct methanol fuel cell with extended reaction zone anode: PtRu and PtRuMo supported on graphite felt

Energy Technology Data Exchange (ETDEWEB)

Bauer, Alex; Gyenge, Elod L.; Oloman, Colin W. [Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, BC (Canada)

2007-05-15

Pressed graphite felt (thickness {proportional_to}350 {mu}m) with electrodeposited PtRu (43 g m{sup -2}, 1.4:1 atomic ratio) or PtRuMo (52 g m{sup -2}, 1:1:0.3 atomic ratio) nanoparticle catalysts was investigated as an anode for direct methanol fuel cells. At temperatures above 333 K the fuel cell performance of the PtRuMo catalyst was superior compared to PtRu. The power density was 2200 W m{sup -2} with PtRuMo at 5500 A m{sup -2} and 353 K while under the same conditions PtRu yielded 1925 W m{sup -2}. However, the degradation rate of the Mo containing catalyst formulation was higher. Compared to conventional gas diffusion electrodes with comparable PtRu catalyst composition and load, the graphite felt anodes gave higher power densities mainly due to the extended reaction zone for methanol oxidation. (author)

Direct methanol fuel cell with extended reaction zone anode: PtRu and PtRuMo supported on graphite felt

Science.gov (United States)

Bauer, Alex; Gyenge, Előd L.; Oloman, Colin W.

Pressed graphite felt (thickness ∼350 μm) with electrodeposited PtRu (43 g m -2, 1.4:1 atomic ratio) or PtRuMo (52 g m -2, 1:1:0.3 atomic ratio) nanoparticle catalysts was investigated as an anode for direct methanol fuel cells. At temperatures above 333 K the fuel cell performance of the PtRuMo catalyst was superior compared to PtRu. The power density was 2200 W m -2 with PtRuMo at 5500 A m -2 and 353 K while under the same conditions PtRu yielded 1925 W m -2. However, the degradation rate of the Mo containing catalyst formulation was higher. Compared to conventional gas diffusion electrodes with comparable PtRu catalyst composition and load, the graphite felt anodes gave higher power densities mainly due to the extended reaction zone for methanol oxidation.

Latest Cretaceous "A2-type" granites in the Sakarya Zone, NE Turkey: Partial melting of mafic lower crust in response to roll-back of Neo-Tethyan oceanic lithosphere

Science.gov (United States)

Karsli, Orhan; Aydin, Faruk; Uysal, Ibrahim; Dokuz, Abdurrahman; Kumral, Mustafa; Kandemir, Raif; Budakoglu, Murat; Ketenci, Murat

2018-03-01

An integrated study of comprehensive geochronological, geochemical, and Sr-Nd-Hf isotopic data was undertaken for the A-type Topcam pluton that intruded within the Sakarya Zone (NE Turkey) with the aims of elucidating its origin and tectonic significance and gaining new insights into the generation of aluminous A-type granites. New LA-ICP-MS zircon U-Pb crystallization ages of 72 and 73 Ma indicate emplacement in the Late Cretaceous time, just after extensive metaluminous I-type magmatism in the area. The pluton consists mainly of alkali feldspar, quartz, plagioclase, amphibole, and biotite with accessory minerals such as magnetite, apatite, and zircon. The outcrop is composed of granite, syenite, monzonite, and quartz monzonite and possesses a wide range of SiO2 content (57-70 wt%) with elevated Ga/Al ratios and low Mg# (mostly negative Eu (Eu/Eu* = 0.31 to 0.86) anomalies on the chondrite-normalized REE diagram. The rocks are enriched in some large ion lithophile elements (e.g., Rb, Th and Ba), and spidergrams show a relative depletion in Nb, Ti, and Sr. The granitic rocks of the pluton have identical 87Sr/86Sr(i) ratios ranging from 0.70518 to 0.70716, relatively low εNd (t) values varying from - 5.5 to - 0.4, and TDM ages (0.82-1.19 Ga). In situ zircon analyses show that the rocks have variable negative and positive εHf (t) values (- 5.5 to 5.9) and Hf two-stage model ages (742 to 1468 Ma), which are indicative of minor addition of juvenile material. Sr-Nd isotope modelling suggests mixing of 70-90% of lower crustal-derived melt with 10-30% of mantle-derived melt at lower crust depths. The heat source for partial melting is provided by upwelling of hot asthenosphere triggered by slab roll-back events. Geochemical and isotopic data reveal that metaluminous A2-type granites were derived from partial melting of the Paleozoic lower continental crust dominated by mafic rocks in amphibolitic composition, with minor input of subcontinental lithospheric mantle

Kinetic studies of isooctane partial oxidation over a nickel-based catalyst

International Nuclear Information System (INIS)

Ibrahim, Hussameldin; Idem, Raphael; Aboudheir, Ahmed

2006-01-01

The production of hydrogen (H 2 ) for fuel cell applications in mobile vehicles by reforming technologies such as partial oxidation of various fossil fuels has gained much attention recently. In this study, the production of H 2 by the catalytic partial oxidation of isooctane ((C 8 H 18 ) used here as a surrogate for gasoline) was investigated over alumina (AI 2 O 3 )supported nickel (Ni) catalyst. The work investigated the kinetics of the partial oxidation of isooctane over a stable Ni/□-AI 2 O 3 catalyst in the range of 863 to 913 K, at atmospheric pressure, W/F i c8 in the range of 1.97 to 8.58 g h mol - 1, and molar feed ratio in the range of 2.0 to 8.0 experiments to obtain kinetic data were performed in a 12.7 mm diameter Inconel micro-reactor housed in an electrically controlled furnace. The chemical reaction was then modeled using rate models developed from the Langmuir-Hinshelwood-hougen-Watson (LHHW) and Eley-Rideal (ER) formulations. The model parameters were estimated using an adaptive Gauss-Newton and Marquardi-Levenberg minimization algorithm. Rival models were screened for their thermodynamic consistency and physicochemical significance of estimated parameters. Langmuir-Hinshelwood-hougen-Watson mechanism requiring the dissociative adsorption of isooctane and oxygen on two different sites appeared to be the most likely pathway for the partial oxidation reaction of isooctane. Reaction order with respect to isooctane indicates the strong coverage of nickel by isooctane. The activation energy of 73±3.1 kJ mol - 1 estimated from the LHHW model is consistent with the trend observed with lower hydrocarbons.(Author)

Energy independent partial wave analysis of the reactions π+-p→Nππ between 1.36 and 1.76GeV c.m.s. energy

International Nuclear Information System (INIS)

Dolbeau, J.; Triantis, F.A.; Neveu, M.; Cadiet, F.

1975-01-01

A new partial wave analysis of the three reactions π - p→pπ - π 0 , π - p→nπ + π - , and π + p→pπ + π 0 is presented at nine c.m. energies between 1.36 and 1.76GeV, using about 91300 Nππ events. Within the framework of the generalized isobar model it is possible to describe the data with Δ, rho and sigma(ππ, i=0) production, as well as to reproduce the π - p→nπ 0 π 0 and π + p→nπ + π + cross sections. New prescriptions for the description of sigma and for the centrifugal barrier term are obtained. Furthermore, at the highest energy, there is evidence for N* production and for the presence of a ππ interaction, contributing about 5% to the cross sections of the reaction π - p→pπ - π 0 and π + p→pπ + π 0 . Finally, Argand plots are presented, showing the main inelastic couplings for ten resonances in this energy range [fr

Studies on glucose metabolism and blood perfusion in childhood partial seizure by positron emission CT

International Nuclear Information System (INIS)

Michihiro, Narumi

1986-01-01

To investigate the glucose metabolism and blood perfusion of the interictal epileptic focus, 15 positron emission tomography (PET) measurements were performed in 14 children with partial seizures (2 with simple partial seizures, 2 with complex partial seizures, and 10 with partial seizures evolving to secondary generalized seizures), comprising 7 males and 7 females aged 1 to 12 years old at the onset of the epileptic seizures. The intervals between the seizure onset and PET examinations were 1 month to 7 years (mean 3 1/4 years). Radiopharmaceuticals such as 11 C-glucose, 11 CO 2 and 11 CO were used as indicators of local cerebral glucose metabolism, blood perfusion and blood flow, respectively. Apart from 2 cases, none of the patients showed abnormal x-ray computed tomographic scans (X-CT). The abnormal X-CT findings included cortical atrophy of the cerebrum apart from the epiletic focus in one case and cavum vergae in the other. Hypometabolism and hypoperfusion at the epileptic focus were observed in 10 patients undergoing single examinations who had suffered from epileptic seizures for more than 1 year. Out of 4 patients who had suffered from epileptic seizures for 1 year or less, one revealed a zone of hypometabolism and hypoperfusion in the epileptic focus and expanded region larger than that of the epileptic focus on the electroencephalogram. Two other patients revealed a zone of hypometabolism and hypoperfusion in an area contralateral to the epileptic focus. In the remaining one patient, PET examinations were performed twice. The initial PET pictures one year after seizure onset revealed a zone of hypermetabolism and hyperperfusion in the cerebellum ipsilateral to the epileptic focus, and the second PET at 6 months after the initial examination revealed hypometabolism and hypoperfusion in the focus, similarly to the 10 cases mentioned above. (J.P.N.)

Proton-transfer reactions in ionized gases

International Nuclear Information System (INIS)

Stiller, W.; Schmidt, R.; Schuster, R.

1985-01-01

Ion-molecule reactions play an important role in various radiolytic processes, e.g. gas-pulse radiolysis, environmental research. For a discussion of mechanisms rate coefficients have to be assessed. Here gas-phase rate coefficients of ion-(polar) molecule reactions are calculated using the ideas of interaction potentials, reactive cross-sections and distribution functions of the translational energies of both the reactants (ions I, molecules M). The starting point of our approach, directed especially to gas-phase proton-transfer reactions, is the idea that the rate coefficient k can be calculated as an ion-molecule capture-rate coefficient multiplied by a 'steric factor' representing the probability for proton transfer. Mutual capture of the reaction partners within a possible reaction zone is caused by the physical interaction between an ion and a polar molecule. A model is discussed. Results are presented. (author)

Highly Active, Carbon-supported, PdSn Nano-core, Partially ...

African Journals Online (AJOL)

Carbon-supported, Pt partially covered, PdSn alloy nanoparticles (Pt-PdSn/C) were synthesized via a metathetical reaction of PdSn alloy nanoparticles, and a platinum precursor. The electrochemical activity was evaluated by methanol oxidation. The Pt-PdSn/C catalysts were characterized by transmission electron ...

Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones

DEFF Research Database (Denmark)

Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene Mark

2015-01-01

Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrifica......Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic...... denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off...... Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically...

Laser-induced partial oxidation of cyclohexane in liquid phase

International Nuclear Information System (INIS)

Oshima, Y.; Wu, X.W.; Koda, S.

1995-01-01

A laser-induced partial oxidation of cyclohexane was studied in the liquid phase. With KrF excimer laser (248 nm) irradiation to neat liquid cyclohexane in which O 2 was dissolved, cyclohexanol and cyclohexanone were obtained with very high selectivities, together with cyclohexane as a minor product. Radical recombination reactions to produce dicyclohexyl ether and bicyclohexyl also took place, while these products were not observed in the gas phase reaction. These experimental results were considered to be due not only to higher concentration of cyclohexane but to the cage effect in the liquid phase oxidation. To clarify the reaction progress including the photoabsorption process, the effects of laser intensity and O 2 pressure on product distribution were studied. (author)

Partially premixed prevalorized kerosene spray combustion in turbulent flow

Energy Technology Data Exchange (ETDEWEB)

Chrigui, M.; Ahmadi, W.; Sadiki, A.; Janicka, J. [Institute for Energy and Powerplant Technology, TU Darmstadt, Petersenstr. 30, 64287 Darmstadt (Germany); Moesl, K. [Lehrstuhl fuer Thermodynamik, TU Muenchen, Boltzmannstr. 15, D-85747 Garching (Germany)

2010-04-15

A detailed numerical simulation of kerosene spray combustion was carried out on a partially premixed, prevaporized, three-dimensional configuration. The focus was on the flame temperature profile dependency on the length of the pre-vaporization zone. The results were analyzed and compared to experimental data. A fundamental study was performed to observe the temperature variation and flame flashback. Changes were made to the droplet diameter, kerosene flammability limits, a combustion model parameter and the location of the combustion initialization. Investigations were performed for atmospheric pressure, inlet air temperature of 90 C and a global equivalence ratio of 0.7. The simulations were carried out using the Eulerian Lagrangian procedure under a fully two-way coupling. The Bray-Moss-Libby model was adjusted to account for the partially premixed combustion. (author)

Characterization of microstructural strengthening in the heat-affected zone of a blast-resistant naval steel

Energy Technology Data Exchange (ETDEWEB)

Yu Xinghua, E-mail: yu.345@osu.edu [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43221 (United States); Caron, Jeremy L. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43221 (United States)] [Welding and Joining Metallurgy Group, Welding Engineering Program, 1248 Arthur E. Adams Drive, Ohio State University, Columbus, OH 43221 (United States); Babu, S.S., E-mail: babu.13@osu.edu [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43221 (United States) and Welding and Joining Metallurgy Group, Welding Engineering Program, 1248 Arthur E. Adams Drive, Ohio State University, Columbus, OH 43221 (United States); Lippold, John C. [Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43221 (United States)] [Welding and Joining Metallurgy Group, Welding Engineering Program, 1248 Arthur E. Adams Drive, Ohio State University, Columbus, OH 43221 (United States); Isheim, Dieter; Seidman, David N. [Department of Materials Science and Engineering, Northwestern University, 2220 North Campus Drive, Evanston, IL 60208 (United States)] [Northwestern University Center for Atom-Probe Tomography, 2220 North Campus Drive, Evanston, IL 60208 (United States)

2010-10-15

The influence of simulated heat-affected zone thermal cycles on the microstructural evolution in a blast-resistant naval steel was investigated by dilatometry, microhardness testing, optical microscopy, electron backscatter diffraction and atom-probe tomography (APT) techniques. Coarsening of Cu precipitates were observed in the subcritical and intercritical heat-affected zones, with partial dissolution in the latter. A small number density of Cu precipitates and high Cu concentration in the matrix of the fine-grained heat-affected zone indicates the onset of Cu precipitate dissolution. Cu clustering in the coarse-grained heat-affected zone indicated the potential initiation of Cu reprecipitation during cooling. Segregation of Cu was also characterized by APT. The hardening and softening observed in the heat-affected zone regions was rationalized using available strengthening models.

Air-sea interactions in the marginal ice zone

Directory of Open Access Journals (Sweden)

Seth Zippel

2016-03-01

Full Text Available Abstract The importance of waves in the Arctic Ocean has increased with the significant retreat of the seasonal sea-ice extent. Here, we use wind, wave, turbulence, and ice measurements to evaluate the response of the ocean surface to a given wind stress within the marginal ice zone, with a focus on the local wind input to waves and subsequent ocean surface turbulence. Observations are from the Beaufort Sea in the summer and early fall of 2014, with fractional ice cover of up to 50%. Observations showed strong damping and scattering of short waves, which, in turn, decreased the wind energy input to waves. Near-surface turbulent dissipation rates were also greatly reduced in partial ice cover. The reductions in waves and turbulence were balanced, suggesting that a wind-wave equilibrium is maintained in the marginal ice zone, though at levels much less than in open water. These results suggest that air-sea interactions are suppressed in the marginal ice zone relative to open ocean conditions at a given wind forcing, and this suppression may act as a feedback mechanism in expanding a persistent marginal ice zone throughout the Arctic.

[Cytostructure of the mantle zone in lymphatic tissue].

Science.gov (United States)

Bednár, B

1993-04-01

Four cellular layers of the follicular mantle zone in palatine tonsil lymphatic tissue were studied by electron microscopy after simultaneous immunophenotypical investigation. The first layer of the mantle zone consisting of small blastic cells was analogous to the small (centrocytoid) blastic layer of germinal centres. The second B monocytoid layer was lacking analogy in basic series of lymphocytes and seemed to be an independent morphological and probably functional unit. Plasmacytoid and clarocellular elements in outer layers of follicular mantle zone were in a way similar to T plasmacytoid and clarocellular components of Sézary syndrome infiltrates but considering transitional forms they had a local origin from incompletely transformed elements of B monocytoid layer. Inner follicular mantle zone was discussed as a source of incompletely transformed B lymphocytes for further mantle layers where their immunophenotypical modulation is taking place according to actual need. Outer mantle layers are aggressive against damaged epithelial and litoral structures and may be instrumental in a common reaction of B and T components.

Crystallization Temperatures of Lower Crustal Gabbros from the Oman Ophiolite and the Persistence of the 'Mush Zone' at Intermediate/Fast Spreading Ridges

Science.gov (United States)

VanTongeren, J. A.

2017-12-01

Oceanic crust is formed when mantle-derived magmas are emplaced at the ridge axis, a zone of intense rifting and extension. Magmas begin to cool and crystallize on-axis, forming what is termed the "Mush Zone", a region of partially molten rocks. Several attempts have been made to understand the nature of the Mush Zone at fast spreading mid-ocean ridges, specifically how much partial melt exists and how far off-axis the Mush Zone extends. Geophysical estimates of P-wave velocity perturbations at the East Pacific Rise show a region of low velocity approximately 1.5-2.5 km off-axis, which can be interpreted to be the result of higher temperature [e.g. Dunn et al., 2000, JGR] or the existence of partial melt. New petrological and geochemical data and methods allow for the calculation of the lateral extent of the Mush Zone in the lower oceanic crust on exposed sections collected from the Oman ophiolite, a paleo-fast/intermediate spreading center. I will present new data quantifying the crystallization temperatures of gabbros from the Wadi Khafifah section of lower oceanic gabbros from the Oman ophiolite. Crystallization temperatures are calculated with the newly developed plagioclase-pyroxene REE thermometer of Sun and Liang [2017, Contrib. Min. Pet.]. There does not appear to be any systematic change in the crystallization temperature of lower crustal gabbros with depth in the crust. In order to quantify the duration of crystallization and the lateral extent of the Mush Zone of the lower crust, crystallization temperatures are paired with estimates of the solidus temperature and cooling rate determined from the same sample, previously constrained by the Ca diffusion in olivine geothermometer/ geospeedometer [e.g. VanTongeren et al., 2008 EPSL]. There is no systematic variation in the closure temperature of Ca in olivine, or the cooling rate to the 800°C isotherm. These results show that gabbros throughout the lower crust of the Oman ophiolite remain in a partially

Reactions between Ti3Al-Nb and mixed second phases

International Nuclear Information System (INIS)

Bowden, D.M.; Sastry, S.M.L.; Smith, P.R.

1989-01-01

In engineered multiphase materials, the interfacial characteristics that develop between individual phases during high-temperature exposure can play a significant role in determining mechanical behavior. In titanium alloys containing silicon carbide and boron fibers, rule-of-mixtures strength values are not realized, primarily because of the chemical reactions that occur between the matrix alloys and these phases. Previous investigations of the reaction between titanium alloys and boron have shown that a uniform reaction layer of the phase TiB 2 is formed, followed by growth of TiB needles. The primary mechanism of this reaction was observed to be the one-way diffusion of boron into titanium. The use of a B 4 C coating on the boron (B 4 C/B) as a diffusion barrier was found to significantly slow the reaction between the titanium and boron. Certain alloy additions to titanium, such as aluminum, vanadium, and molybdenum, can increase the chemical compatibility of these two phases. For the case of SiC, the reaction zone is formed by the interdiffusion of silicon and carbon atoms with titanium. X-ray diffraction studies have shown the reaction components to include TiC, Ti 5 Si 3 , and TiSi 2 . In the present study, the reactions between a Ti 3 Al alloy and both B 4 C/B and SiC have been examined. Reaction models are proposed to describe the development of the chemical interaction zone formed between these phases

A partial wave analysis of the (3π)0 system from the charge exchange reaction π+n→π+π-π0p at 4 GeV/c

International Nuclear Information System (INIS)

Emms, M.J.; Jones, G.T.; Kinson, J.B.; Stacey, B.J.; Votruba, M.F.; Woodworth, P.L.; Bell, I.G.; Dale, M.; Major, J.V.; Charlesworth, J.A.; Crennell, D.J.; Sekulin, R.L.

1975-10-01

From a partial wave analysis of the (3π) 0 state in the charge exchange reaction π + n→π + π - π 0 p, strong unnatural parity is observed as well as natural parity production. The observed natural parity states are identified with well-established resonances. The unnatural parity production is consistent with Reggeized Deck model predictions, with the exception of the I = 1 Jsup(p) = 1 + state. Here there is no evidence for A 1 production at approximately 1.1 GeV, but the data could support resonance production at higher masses. (author)

Buoyancy Effect of Ionic Vacancy on the Change of the Partial Molar Volume in Ferricyanide-Ferrocyanide Redox Reaction under a Vertical Gravity Field

Directory of Open Access Journals (Sweden)

Yoshinobu Oshikiri

2013-01-01

Full Text Available With a gravity electrode (GE in a vertical gravity field, the buoyancy effect of ionic vacancy on the change of the partial molar volume in the redox reaction between ferricyanide (FERRI and ferrocyanide (FERRO ions was examined. The buoyancy force of ionic vacancy takes a positive or negative value, depending on whether the rate-determining step is the production or extinction of the vacancy. Though the upward convection over an upward electrode in the FERRO ion oxidation suggests the contribution of the positive buoyancy force arising from the vacancy production, the partial molar volume of the vacancy was not measured. On the other hand, for the downward convection under a downward electrode in the FERRI ion reduction, it was not completely but partly measured by the contribution of the negative buoyancy force from the vacancy extinction. Since the lifetime of the vacancy is decreased by the collision between ionic vacancies during the convection, the former result was ascribed to the shortened lifetime due to the increasing collision efficiency in the enhanced upward convection over an upward electrode, whereas the latter was thought to arise from the elongated lifetime due to the decreasing collision efficiency by the stagnation under the downward electrode.

Phosphorus zoning as a recorder of crystal growth kinetics

DEFF Research Database (Denmark)

Baziotis, I.; Asimow, P.D.; Ntaflos, T.

2017-01-01

spectrometry. The petrogenetic history of each vein involves melt intrusion, cooling accompanied by both wall-rock reaction and crystallization, quench of melt to a glass, and possibly later modifications. Exotic secondary olivine crystals in the veins display concentric phosphorus (P)-rich zoning, P...

Phase equilibria constraints on models of subduction zone magmatism

Science.gov (United States)

Myers, James D.; Johnston, Dana A.

Petrologic models of subduction zone magmatism can be grouped into three broad classes: (1) predominantly slab-derived, (2) mainly mantle-derived, and (3) multi-source. Slab-derived models assume high-alumina basalt (HAB) approximates primary magma and is derived by partial fusion of the subducting slab. Such melts must, therefore, be saturated with some combination of eclogite phases, e.g. cpx, garnet, qtz, at the pressures, temperatures and water contents of magma generation. In contrast, mantle-dominated models suggest partial melting of the mantle wedge produces primary high-magnesia basalts (HMB) which fractionate to yield derivative HAB magmas. In this context, HMB melts should be saturated with a combination of peridotite phases, i.e. ol, cpx and opx, and have liquid-lines-of-descent that produce high-alumina basalts. HAB generated in this manner must be saturated with a mafic phase assemblage at the intensive conditions of fractionation. Multi-source models combine slab and mantle components in varying proportions to generate the four main lava types (HMB, HAB, high-magnesia andesites (HMA) and evolved lavas) characteristic of subduction zones. The mechanism of mass transfer from slab to wedge as well as the nature and fate of primary magmas vary considerably among these models. Because of their complexity, these models imply a wide range of phase equilibria. Although the experiments conducted on calc-alkaline lavas are limited, they place the following limitations on arc petrologic models: (1) HAB cannot be derived from HMB by crystal fractionation at the intensive conditions thus far investigated, (2) HAB could be produced by anhydrous partial fusion of eclogite at high pressure, (3) HMB liquids can be produced by peridotite partial fusion 50-60 km above the slab-mantle interface, (4) HMA cannot be primary magmas derived by partial melting of the subducted slab, but could have formed by slab melt-peridotite interaction, and (5) many evolved calc

Partial pressures of oxygen, phosphorus and fluorine in some lunar lavas

Science.gov (United States)

Nash, W. P.; Hausel, W. D.

1973-01-01

Lunar sample 14310 is a feldspar-rich basalt which shows no evidence of shock deformation or recrystallization. Pyroxenes include Mg-rich orthopyroxene, pigeonite and augite; pyroxferroite occurs in the interstitial residuum. Plagioclase feldspars are zoned from An(96) to An(67), and variations in feldspar compositions do not necessarily indicate loss of Na during eruption of the lava. Opaque phases include ilmenite, ulvospinel, metallic iron, troilite, and schreibersite. Both whitlockite and apatite are present, and the interstitial residua contain baddeleyite, tranquillityite and barium-rich sanidine. Theoretical calculations provide estimates of partial pressures of oxygen, phosphorus, and fluorine in lunar magmas. In general, partial pressures of oxygen are restricted by the limiting assemblages of iron-wuestite and ilmenite-iron-rutile; phosphorus partial pressures are higher in lunar magmas than in terrestrial lavas. The occurrence of whitlockite indicates significantly lower fugacities of fluorine in lunar magmas than in terrestrial magmas.

Evidence for selection in response to radiation exposure: Pinus sylvestris in the Chernobyl exclusion zone

International Nuclear Information System (INIS)

Kuchma, Oleksandra; Finkeldey, Reiner

2011-01-01

Changes of genetic structures due to viability selection are likely to occur in populations exposed to rapidly and extremely changing environmental conditions after catastrophic events. However, very little is known about the extent of selective responses and in particular the proportion of the genome involved in putatively adaptive reactions for non-model plants. We used amplified fragment length polymorphisms (AFLPs) in order to investigate genetic differences between pine (Pinus sylvestris) trees which were partially exposed to extreme environmental conditions. Genetic variation patterns of pines exposed to high radiation in the Chernobyl exclusion zone with or without phenotypic stress symptoms were compared to control trees with a similar origin. Six percent of the investigated loci (15 of 222 loci) were identified as candidates for selective responses. Moderate differentiation was observed between groups of trees showing either weak or strong phenotypic responses to high radiation levels. - Highlights: → Genetic variation patterns of pines exposed to high radiation were investigated. → Pines with or without phenotypic stress symptoms were compared to control trees. → AFLP markers were used to reveal evidences of selection processes. → 15 of 222 loci are identified as candidates for selective responses. → Moderate differentiation is observed between irradiated and control trees. - Genetic responses to the exposure of trees to radiation in the Chernobyl zone may involve adaptive changes at a comparatively large part of the genome.

Tantrums, Emotion Reactions and Their EEG Correlates in Childhood Benign Rolandic Epilepsy vs. Complex Partial Seizures: Exploratory Observations

Directory of Open Access Journals (Sweden)

Michael Potegal

2018-03-01

Full Text Available We explored associations between EEG pathophysiology and emotional/behavioral (E/B problems of children with two types of epilepsy using standard parent questionnaires and two new indicators: tantrums recorded by parents at home and brief, emotion-eliciting situations in the laboratory. Children with Benign Rolandic epilepsy (BRE, N = 6 reportedly had shorter, more angry tantrums from which they recovered quickly. Children with Complex Partial Seizures (CPS, N = 13 had longer, sadder tantrums often followed by bad moods. More generally, BRE correlated with anger and aggression; CPS with sadness and withdrawal. Scores of a composite group of siblings (N = 11 were generally intermediate between the BRE and CPS groups. Across all children, high voltage theta and/or interictal epileptiform discharges (IEDs correlated with negative emotional reactions. Such EEG abnormalities in left hemisphere correlated with greater social fear, right hemisphere EEG abnormalities with greater anger. Right hemisphere localization in CPS was also associated with parent-reported problems at home. If epilepsy alters neural circuitry thereby increasing negative emotions, additional assessment of anti-epileptic drug treatment of epilepsy-related E/B problems would be warranted.

Articular Cartilage Increases Transition Zone Regeneration in Bone-tendon Junction Healing

Science.gov (United States)

Qin, Ling; Lee, Kwong Man; Leung, Kwok Sui

2008-01-01

The fibrocartilage transition zone in the direct bone-tendon junction reduces stress concentration and protects the junction from failure. Unfortunately, bone-tendon junctions often heal without fibrocartilage transition zone regeneration. We hypothesized articular cartilage grafts could increase fibrocartilage transition zone regeneration. Using a goat partial patellectomy repair model, autologous articular cartilage was harvested from the excised distal third patella and interposed between the residual proximal two-thirds bone fragment and tendon during repair in 36 knees. We evaluated fibrocartilage transition zone regeneration, bone formation, and mechanical strength after repair at 6, 12, and 24 weeks and compared them with direct repair. Autologous articular cartilage interposition resulted in more fibrocartilage transition zone regeneration (69.10% ± 14.11% [mean ± standard deviation] versus 8.67% ± 7.01% at 24 weeks) than direct repair at all times. There was no difference in the amount of bone formation and mechanical strength achieved. Autologous articular cartilage interposition increases fibrocartilage transition zone regeneration in bone-tendon junction healing, but additional research is required to ascertain the mechanism of stimulation and to establish the clinical applicability. PMID:18987921

Study of consistency between (γ,xn), [(γ,n) (γ,np)] and (γ2n) reaction cross sections using data systematics

International Nuclear Information System (INIS)

Varlamov, V.V.; Ishkhanov, B.S.

2002-08-01

The majority of published data for photoneutron reaction both total and partial cross section data obtained using both bremsstrahlung and quasimonoenergetic photon beams has been analyzed systematically. The last kind data were treated separately for results obtained at USA National Lawrence Livermore Laboratory and at Centre d.Etudes Nucleaires de Saclay (France). It was found out that as a rule total photoneutron reaction cross sections obtained at Livermore differ (being smaller in amplitude) from that of other laboratories. The Saclay-Livermore data discrepancies were analyzed in details. Combined the result of this analysis with that of analysis of partial photoneutron reactions [(γ,n) + (γ,np)] and (γ,2n) cross sections balance between Livermore and Saclay data published before the following recommendation was formulated: for reliable balance of total photoneutron (γ,xn) and partial [(γ,n) + [(γ,np)] and (γ,2n) reactions cross section absolute values the Livermore (not Saclay) data must be used but multiplied to the parameter 1.122. Saclay total reaction data could be used directly but partial reaction data must be recalculated via complex procedure. (author)

Partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor

KAUST Repository

Zhang, Xuming; Cha, Min

2015-01-01

We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight

Reaction of O+, CO+, and CH+ ions with atomic hydrogen

International Nuclear Information System (INIS)

Federer, W.; Villinger, H.; Howorka, F.; Lindinger, W.; Tosis, P.; Bassi, D.; Ferguson, E.

1984-01-01

Rate coefficients for reactions of the ions O + , CO + , and CH + with atomic hydrogen have been measured for the first time at 300 K. This provides basic data for the ion chemistry of planetary atmospheres, cometary atmospheres, and interstellar molecular clouds. The O + +H measurement supports quantal calculations of this reaction. The CO + +H reaction provides an example of partial spin nonconservation in a charge-transfer reaction occurring in a deep potential well. Reactions of the same ions with H 2 that have been measured elsewhere are also reported

Roy-Steiner equations for {pi}N scattering - The Muskhelishvili-Omnes problem for the t-channel partial waves

Energy Technology Data Exchange (ETDEWEB)

Ditsche, Christoph; Hoferichter, Martin; Kubis, Bastian [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn (Germany); Bethe Center for Theoretical Physics, Bonn (Germany); Meissner, Ulf G. [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn (Germany); Institut fuer Kernphysik (Theorie), Institute for Advanced Simulations, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Bethe Center for Theoretical Physics, Bonn (Germany)

2011-07-01

Starting from (subtracted) hyperbolic dispersion relations for {pi}N scattering, which are based on the general principles of Lorentz invariance, unitarity, crossing and analyticity as well as isospin symmetry, we propose a closed system of (subtracted) hyperbolic partial wave dispersion relations for the partial waves f{sup I}{sub l{+-}}({radical}(s)) of the s-channel reaction {pi}N{yields}{pi}N and the partial waves f{sup J}{sub {+-}}(t) of the t-channel reaction {pi}{pi}{yields} anti NN in the spirit of Roy and Steiner. A key step to the ultimate goal of solving this Roy-Steiner system is to first solve the corresponding (subtracted) Muskhelishvili-Omnes problem with inelasticities and a finite matching point for the lowest t-channel partial waves f{sup 0}{sub +}(t), f{sup 1}{sub {+-}}(t). The recent status of this ongoing effort is presented.

Partially-Functionalized Isotactic Polystyrene with Blocky Comonomer Segments

Science.gov (United States)

Siegel, Ariel; Powers, Wayne; Ryu, Chang Y.

2012-02-01

Isotactic polystyrenes (iPSs) have been functionalized in solution, while the accessibility of functionalizing agent is limited by the formation of crystalline domains at various temperatures. The chemical system used is the borylated isotactic polystyrene system, and we investigated the temperature effects on reaction kinetics to ultimately control the blockiness of borylated segments in the resulting copolymer. The chemical composition of partially borylated iPS reaches a steady state that is dependent on temperature. This synthesis has been performed at many different temperatures, with different steady states being reached at different temperatures. Further analysis by differential scanning calorimetry (DSC) has shown that the higher temperature reactions have greater effect on breaking down the crystal lattice structure of the isotactic polystyrene. As a result, the lower temperature reactions affect the crystalline structure less, and the resulting copolymer has more blockiness.

OXIDATIVE-REFORMING OF METHANE AND PARTIAL OXIDATION OF METHANE REACTIONS OVER NiO/PrO2/ZrO2 CATALYSTS: EFFECT OF NICKEL CONTENT

Directory of Open Access Journals (Sweden)

Y. J. O. Asencios

Full Text Available Abstract In this work the behavior of NiO-PrO2-ZrO2 catalysts containing various nickel loadings was evaluated in the partial oxidation of methane and oxidative-reforming reactions of methane. The catalysts were characterized by X-Ray Diffraction Analysis (in situ-XRD, Temperature Programmed Reduction (H2-TPR, Scanning Electron Microscopy (SEM/EDX and Adsorption-Desorption of nitrogen (BET area. The reactions were carried out at 750 °C and 1 atm for 5 hours. The catalysts were studied with different nickel content: 0, 5, 10 and 15% (related to total weight of catalyst, wt%. In both reactions, the catalyst containing the mixture of the three oxides (NiO/PrO2/ZrO2 with 15% nickel (15NiPrZr catalyst showed the best activity for the conversion of the reactants into Syngas and showed high selectivity for H2 and CO. The results suggest that the promoter PrO2 and the Niº centers are in a good proportion in the catalyst with 15% Ni. Our results showed that low nickel concentrations in the catalyst led to high metallic dispersion; however, very low nickel concentrations did not favor the methane transformation into Syngas. The catalyst containing only NiO/ZrO2 in the mixture was not sufficient for the catalysis. The presence of the promoter PrO2 was very important for the catalysis of the POM.

Design improvement for partial penetration welds of Pressurizer heater sleeves to head junctures

International Nuclear Information System (INIS)

Kim, Jin-Seon; Lee, Kyoung-Jin; Park, Tae-Jung; Kim, Moo-Yong

2007-01-01

ASME Code, Section III allows partial penetration welds for openings for instrumentation on which there are substantially no piping reactions and requires to have interference fit or limited diametral clearance between nozzles and vessel penetrations for the partial penetration welds. Pressurizer heater sleeves are nonaxisymmetrically attached on the hill-side of bottom head by partial penetration welds. The excessive stresses in the partial penetration weld regions of the heater sleeves are induced by pressure and thermal transient loads and also by the deformation due to manual welding process. The purpose of this study is 1) to improve design for the partial penetration welds between heater sleeves to head junctures, 2) to demonstrate the structural integrity according to the requirements of ASME Code, Section III and 3) to improve welding procedure considering the proposed design

INDICATION OF INSENSITIVITY OF PLANETARY WEATHERING BEHAVIOR AND HABITABLE ZONE TO SURFACE LAND FRACTION

International Nuclear Information System (INIS)

Abbot, Dorian S.; Ciesla, Fred J.; Cowan, Nicolas B.

2012-01-01

It is likely that unambiguous habitable zone terrestrial planets of unknown water content will soon be discovered. Water content helps determine surface land fraction, which influences planetary weathering behavior. This is important because the silicate-weathering feedback determines the width of the habitable zone in space and time. Here a low-order model of weathering and climate, useful for gaining qualitative understanding, is developed to examine climate evolution for planets of various land-ocean fractions. It is pointed out that, if seafloor weathering does not depend directly on surface temperature, there can be no weathering-climate feedback on a waterworld. This would dramatically narrow the habitable zone of a waterworld. Results from our model indicate that weathering behavior does not depend strongly on land fraction for partially ocean-covered planets. This is powerful because it suggests that previous habitable zone theory is robust to changes in land fraction, as long as there is some land. Finally, a mechanism is proposed for a waterworld to prevent complete water loss during a moist greenhouse through rapid weathering of exposed continents. This process is named a 'waterworld self-arrest', and it implies that waterworlds can go through a moist greenhouse stage and end up as planets like Earth with partial ocean coverage. This work stresses the importance of surface and geologic effects, in addition to the usual incident stellar flux, for habitability.

INDICATION OF INSENSITIVITY OF PLANETARY WEATHERING BEHAVIOR AND HABITABLE ZONE TO SURFACE LAND FRACTION

Energy Technology Data Exchange (ETDEWEB)

Abbot, Dorian S.; Ciesla, Fred J. [Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Cowan, Nicolas B., E-mail: abbot@uchicago.edu [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2131 Tech Drive, Evanston, IL 60208 (United States)

2012-09-10

It is likely that unambiguous habitable zone terrestrial planets of unknown water content will soon be discovered. Water content helps determine surface land fraction, which influences planetary weathering behavior. This is important because the silicate-weathering feedback determines the width of the habitable zone in space and time. Here a low-order model of weathering and climate, useful for gaining qualitative understanding, is developed to examine climate evolution for planets of various land-ocean fractions. It is pointed out that, if seafloor weathering does not depend directly on surface temperature, there can be no weathering-climate feedback on a waterworld. This would dramatically narrow the habitable zone of a waterworld. Results from our model indicate that weathering behavior does not depend strongly on land fraction for partially ocean-covered planets. This is powerful because it suggests that previous habitable zone theory is robust to changes in land fraction, as long as there is some land. Finally, a mechanism is proposed for a waterworld to prevent complete water loss during a moist greenhouse through rapid weathering of exposed continents. This process is named a 'waterworld self-arrest', and it implies that waterworlds can go through a moist greenhouse stage and end up as planets like Earth with partial ocean coverage. This work stresses the importance of surface and geologic effects, in addition to the usual incident stellar flux, for habitability.

Measurement of the power trasient and valve closing time, for the zone control system, during a programmed shutdown in August 1989 and its relation with the class IV partial loss event occurred on 27/12/88 in CNE (Embalse nuclear power plant)

International Nuclear Information System (INIS)

Paz, A.O. de; Moreno, C.A.; Vinez, J.C.

1990-01-01

A description is made of a number of measurements performed during the programmed shutdown on Embalse nuclear power plant (CNE) (August 1989) to validate the existance of a reactivity insertion owing to the emptying of the liquid zone control system. In the event occurred on 27/12/88 when there was a partial loss Cl IV. Once the existance of this contribution was confirmed, the pertinent corrective measures were taken and the test was repeated to verify the effectiveness of the latter. The temporal evolution of a number of neutronic variables and process variables of the liquid zone system were stored in an IBM-PC XT equipped with analog-to-digital converters, for later analysis. (Author) [es

Interference from lupus anticoagulant on von Willebrand factor measurement in splenic marginal zone lymphoma

DEFF Research Database (Denmark)

Vinholt, Pernille J; Nybo, Mads

2015-01-01

We present a case concerning a patient with splenic marginal zone lymphoma (SMZL) and isolated prolonged activated partial thromboplastin time (aPTT) caused by lupus anticoagulant. Von Willebrand factor (VWF) activity and antigen were immeasurable by latex particle immunoturbidimetric assays...

Surface modification by preparation of buffer zone in glow-discharge plasma

International Nuclear Information System (INIS)

Cho, D.L.

1986-01-01

Reactive species, energetic particles, and uv radiation in the plasma created by a glow discharge strongly interact with solid surfaces under the influence of the plasma. As a result of the strong interaction, various physical and chemical reactions, unique and advantageous for the surface modification of solid materials, occur on the solid surfaces. The surface modification is carried out through formation of a thin buffering layer on the solid surface. The preparation of a buffer zone on solid surfaces for surface modification is described. Two kinds of a buffer zone are prepared by plasma polymerization, or simultaneous sputter deposition of electrode material with plasma polymerization: a transitional buffer zone and a graded buffer zone. Important factors for preparation of the buffer zone (pre-conditioning of a substrate surface, thin-film deposition, post-treatment of the film, magnetron discharge, energy input, geometry of a substrate and a plasma) are discussed

Distribution of gases in the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Illinois

Science.gov (United States)

Striegl, Robert G.

1988-01-01

The unsaturated zone is a medium that provides pneumatic communication for the movement of gases from wastes buried in landfills to the atmosphere, biota, and groundwater. Gases in unsaturated glacial and eolian deposits near a waste-disposal trench at the low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois, were identified, and the spatial and temporal distributions of the partial pressures of those gases were determined for the period January 1984 through January 1986. Methods for the collection and analyses of the gases are described, as are geologic and hydrologic characteristics of the unsaturated zone that affect gas transport. The identified gases, which are of natural and of waste origin, include nitrogen, oxygen, and argon, carbon dioxide, methane, propane, butane, tritiated water vapor, 14carbon dioxide, and 222 radon. Concentrations of methane and 14carbon dioxide originated at the waste, as shown by partial-pressure gradients of the gases; 14carbon dioxide partial pressures exceeded natural background partial pressures by factors greater than 1 million at some locations. Variations in partial pressures of oxygen and carbon dioxide were seasonal among piezometers because of increased root and soil-microbe respiration during summer. Variations in methane and 14carbon dioxide partial pressures were apparently related to discrete releases from waste sources at unpredictable intervals of time. No greater than background partial pressures for tritiated water vapor or 222 radon were measured. (USGS)

Temperature dependence on sodium-water chemical reaction

International Nuclear Information System (INIS)

Tamura, Kenta; Deguchi, Yoshihiro; Suzuki, Koichi; Takata, Takashi; Yamaguchi, Akira; Kikuchi, Shin; Ohshima, Hiroyuki

2012-01-01

In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes. This process ends up damages on the heat transport equipment in the SFR. Therefore, the study on sodium-water chemical reactions is of paramount importance for security reasons. This study aims to clarify the sodium-water reaction mechanisms using laser diagnostics. A quasi one-dimensional flame model is also applied to a sodium-water counter-flow reaction field. Temperature, H 2 , H 2 O, OH, Na and Particulate matter were measured using laser induced fluorescence and CARS in the counter-flow reaction field. The temperature of the reaction field was also modified to reduce the condensation of Na in the reaction zone. (author)

A thermodynamic and kinetic study of the de- and rehydration of Ca(OH){sub 2} at high H{sub 2}O partial pressures for thermo-chemical heat storage

Energy Technology Data Exchange (ETDEWEB)

Schaube, F.; Koch, L. [German Aerospace Center, Institute of Technical Thermodynamics, Pfaffenwaldring 38-40, 70569 Stuttgart (Germany); Woerner, A., E-mail: antje.woerner@dlr.de [German Aerospace Center, Institute of Technical Thermodynamics, Pfaffenwaldring 38-40, 70569 Stuttgart (Germany); Mueller-Steinhagen, H. [German Aerospace Center, Institute of Technical Thermodynamics, Pfaffenwaldring 38-40, 70569 Stuttgart (Germany)

2012-06-20

Highlights: Black-Right-Pointing-Pointer Investigation of the thermodynamic equilibrium and reaction enthalpy of 'Ca(OH){sub 2} {r_reversible} CaO + H{sub 2}O'. Black-Right-Pointing-Pointer Investigation of the reaction kinetics of the dehydration of Ca(OH){sub 2} at partial pressures up to 956 mbar. Black-Right-Pointing-Pointer Investigation of the reaction kinetics of the rehydration of Ca(OH){sub 2} at partial pressures up to 956 mbar. - Abstract: Heat storage technologies are used to improve energy efficiency of power plants and recovery of process heat. Storing thermal energy by reversible thermo-chemical reactions offers a promising option for high storage capacities especially at high temperatures. Due to its low material cost, the use of the reversible reaction Ca(OH){sub 2} Rightwards-Harpoon-Over-Leftwards-Harpoon CaO + H{sub 2}O has been proposed. This paper reports on the physical properties such as heat capacity, thermodynamic equilibrium, reaction enthalpy and kinetics. To achieve high reaction temperatures, high H{sub 2}O partial pressures are required. Therefore the cycling stability is confirmed for H{sub 2}O partial pressures up to 95.6 kPa and the dehydration and hydration kinetics are studied. Quantitative data are collected and expressions are derived which are in good agreement with the presented measurements. At 1 bar H{sub 2}O partial pressure the expected equilibrium temperature is 505 Degree-Sign C and the reaction enthalpy is 104.4 kJ/mol.

Propagation of hydroclimatic variability through the critical zone

Science.gov (United States)

Porporato, A. M.; Calabrese, S.; Parolari, A.

2016-12-01

The interaction between soil moisture dynamics and mineral-weathering reactions (e.g., ion exchange, precipitation-dissolution) affects the availability of nutrients to plants, composition of soils, soil acidification, as well as CO2 sequestration. Across the critical zone (CZ), this interaction is responsible for propagating hydroclimatic fluctuations to deeper soil layers, controlling weathering rates via leaching events which intermittently alter the alkalinity levels. In this contribution, we analyze these dynamics using a stochastic modeling approach based on spatially lumped description of soil hydrology and chemical weathering reactions forced by multi-scale temporal hydrologic variability. We quantify the role of soil moisture dynamics in filtering the rainfall fluctuations through its impacts on soil water chemistry, described by a system of ordinary differential equations (and algebraic equations, for the equilibrium reactions), driving the evolution of alkalinity, pH, the chemical species of the soil solution, and the mineral-weathering rate. A probabilistic description of the evolution of the critical zone is thus obtained, allowing us to describe the CZ response to long-term climate fluctuations, ecosystem and land-use conditions, in terms of key variables groups. The model is applied to the weathering rate of albite in the Calhoun CZ observatory and then extended to explore similarities and differences across other CZs. Typical time scales of response and degrees of sensitivities of CZ to hydroclimatic fluctuations and human forcing are also explored.

Introduction to the structures and processes of subduction zones

Science.gov (United States)

Zheng, Yong-Fei; Zhao, Zi-Fu

2017-09-01

Subduction zones have been the focus of many studies since the advent of plate tectonics in 1960s. Workings within subduction zones beneath volcanic arcs have been of particular interest because they prime the source of arc magmas. The results from magmatic products have been used to decipher the structures and processes of subduction zones. In doing so, many progresses have been made on modern oceanic subduction zones, but less progresses on ancient oceanic subduction zones. On the other hand, continental subduction zones have been studied since findings of coesite in metamorphic rocks of supracrustal origin in 1980s. It turns out that high-pressure to ultrahigh-pressure metamorphic rocks in collisional orogens provide a direct target to investigate the tectonism of subduction zones, whereas oceanic and continental arc volcanic rocks in accretionary orogens provide an indirect target to investigate the geochemistry of subduction zones. Nevertheless, metamorphic dehydration and partial melting at high-pressure to ultrahigh-pressure conditions are tectonically applicable to subduction zone processes at forearc to subarc depths, and crustal metasomatism is the physicochemical mechanism for geochemical transfer from the slab to the mantle in subduction channels. Taken together, these provide us with an excellent opportunity to find how the metamorphic, metasomatic and magmatic products are a function of the structures and processes in both oceanic and continental subduction zones. Because of the change in the thermal structures of subduction zones, different styles of metamorphism, metasomatism and magmatism are produced at convergent plate margins. In addition, juvenile and ancient crustal rocks have often suffered reworking in episodes independent of either accretionary or collisional orogeny, leading to continental rifting metamorphism and thus rifting orogeny for mountain building in intracontinental settings. This brings complexity to distinguish the syn

Partial oxidation of municipal sludge with activited carbon catalyst in supercritical water

International Nuclear Information System (INIS)

Guo Yang; Wang Shuzhong; Gong Yanmeng; Xu Donghai; Tang Xingying; Ma Honghe

2010-01-01

The partial oxidation (POX) characteristics of municipal sludge in supercritical water (SCW) were investigated by using batch reactor. Effects of reaction parameters such as oxidant equivalent ratio (OER), reaction time and temperature were investigated. Activated carbon (AC) could effectively improve the mole fraction of H 2 in gas product at low OER. However, high OER (greater than 0.3) not only led to the combustion reaction of CO and H 2 , but also caused corrosion of reactor inner wall. Hydrogenation and polymerization of the intermediate products are possible reasons for the relative low COD removal rate in our tests. Metal oxide leached from the reactor inner wall and the main components of the granular sludge were deposited in the AC catalyst. Reaction time had more significant effect on BET surface area of AC than OER had. Long reaction time led to the methanation reaction following hydrolysis and oxidation reaction of AC in SCW in the presence of oxygen. Correspondingly, the possible reaction mechanisms were proposed.

27Al MAS NMR spectroscopic identification of reaction intermediates in the carbothermal reduction and nitridation of alumina

International Nuclear Information System (INIS)

Jung, Woo-Sik; Chae, Seen-Ae

2010-01-01

The reaction intermediates in the carbothermal reduction and nitridation (CRN) reaction of γ-Al 2 O 3 were identified by 27 Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. This identification ruled out the possibility of a reaction mechanism involving the gaseous reaction intermediates. In the CRN reaction of γ-Al 2 O 3 , AlO 4 units were converted to AlN stepwise via AlN x O 4-x (x = 1, 2, 3) intermediates, while AlO 6 units were more slowly converted to AlN than AlO 4 units and the NMR peaks of partially nitridated AlO 6 units were not detected. The NMR peak intensities of partially nitridated AlO 4 units became weaker with increasing reaction temperature.

The Drosophila KIF1A homolog unc-104 is important for site-specific active zone maturation

Directory of Open Access Journals (Sweden)

Yao V. Zhang

2016-09-01

Full Text Available Abstract Mutations in the kinesin-3 family member KIF1A have been associated with hereditary spastic paraplegia, hereditary sensory and autonomic neuropathy type 2 and intellectual disability. Both autosomal recessive and autosomal dominant forms of inheritance have been reported. Loss of KIF1A or its homolog unc-104 causes early postnatal or embryonic lethality in mice and Drosophila, respectively. In this study we use a previously described hypomorphic allele of unc-104, unc-104bris, to investigate the impact of partial loss-of-function of kinesin-3 function on active zone formation at the Drosophila neuromuscular junction. unc-104bris mutants exhibit synaptic defects where a subset of synapses at the neuromuscular junction lack the key active zone organizer protein Bruchpilot. Modulating synaptic Bruchpilot levels by ectopic overexpression or RNAi-mediated knockdown suggests that the loss of active zone components such as Ca2+ channel and Liprin-α from these synapses is caused by impaired kinesin-3 transport rather than due to the absence of Bruchpilot at these synapses. In addition to defects in active zone maturation, unc-104bris mutants display impaired transport of dense core vesicles and synaptic vesicle associated proteins, among which Rab3 has been shown to regulate the distribution of Bruchpilot to active zones. Overexpression of Rab3 partially ameliorates synaptic phenotypes of unc-104bris neuromuscular junction, suggesting that lack of presynaptic Rab3 may contribute to defects in synapse maturation.

Special Features of Strain Localization and Nanodipoles of Partial Disclinations in the Region of Elastic Distortions

Science.gov (United States)

Tyumentsev, A. N.; Ditenberg, I. A.; Sukhanov, I. I.

2018-02-01

In the zones of strain localization in the region of elastic distortions and nanodipoles of partial disclinations representing the defects of elastically deformed medium, a theoretical analysis of the elastically stressed state and the energy of these defects, including the cases of their transformation into more complex ensembles of interrelated disclinations, is performed. Using the analytical results, the mechanisms of strain localization are discussed in the stages of nucleation and propagation of the bands of elastic and plastic strain localization formed in these zones (including the cases of nanocrystalline structure formation).

Reaction-diffusion fronts with inhomogeneous initial conditions

Energy Technology Data Exchange (ETDEWEB)

Bena, I [Departement de Physique Theorique, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Droz, M [Departement de Physique Theorique, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Martens, K [Departement de Physique Theorique, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Racz, Z [Institute for Theoretical Physics, Eoetvoes University, 1117 Budapest (Hungary)

2007-02-14

Properties of reaction zones resulting from A+B {yields} C type reaction-diffusion processes are investigated by analytical and numerical methods. The reagents A and B are separated initially and, in addition, there is an initial macroscopic inhomogeneity in the distribution of the B species. For simple two-dimensional geometries, exact analytical results are presented for the time evolution of the geometric shape of the front. We also show using cellular automata simulations that the fluctuations can be neglected both in the shape and in the width of the front.

Detecting and correcting partial errors: Evidence for efficient control without conscious access.

Science.gov (United States)

Rochet, N; Spieser, L; Casini, L; Hasbroucq, T; Burle, B

2014-09-01

Appropriate reactions to erroneous actions are essential to keeping behavior adaptive. Erring, however, is not an all-or-none process: electromyographic (EMG) recordings of the responding muscles have revealed that covert incorrect response activations (termed "partial errors") occur on a proportion of overtly correct trials. The occurrence of such "partial errors" shows that incorrect response activations could be corrected online, before turning into overt errors. In the present study, we showed that, unlike overt errors, such "partial errors" are poorly consciously detected by participants, who could report only one third of their partial errors. Two parameters of the partial errors were found to predict detection: the surface of the incorrect EMG burst (larger for detected) and the correction time (between the incorrect and correct EMG onsets; longer for detected). These two parameters provided independent information. The correct(ive) responses associated with detected partial errors were larger than the "pure-correct" ones, and this increase was likely a consequence, rather than a cause, of the detection. The respective impacts of the two parameters predicting detection (incorrect surface and correction time), along with the underlying physiological processes subtending partial-error detection, are discussed.

Detection of uranium extraction zone by axial temperature profiles in a pulsed column for Purex process

International Nuclear Information System (INIS)

Tsukada, T.; Takahashi, K.

1991-01-01

A new method was presented for detecting uranium extraction zone in a pulsed column by means of measuring axial temperature profile originated from reaction heat during uranium extraction. Key parameters of the temperature profiles were estimated with a code developed for calculating temperature profiles in a direct-contact heat exchanger such as a pulsed column, and were verified using data from a small pulsed column simulating reaction heat with injecting hot water. Finally, the results were compared with those from an actual uranium extraction tests, indicating that the method presented was promising for detecting uranium extraction zone in a pulsed column. (author)

Distinct Roles of the C-terminal 11th Transmembrane Helix and Luminal Extension in the Partial Reactions Determining the High Ca2+ Affinity of Sarco(endo)plasmic Reticulum Ca2+-ATPase Isoform 2b (SERCA2b)

DEFF Research Database (Denmark)

Clausen, Johannes D; Vandecaetsbeek, Ilse; Wuytack, Frank

2012-01-01

of each of these parts and their interactions with the SERCA environment were examined by transient kinetic analysis of the partial reaction steps in the Ca2+ transport cycle in mutant and chimeric Ca2+-ATPase constructs. Manipulations to the LE of SERCA2b markedly increased the rate of Ca2+ dissociation...

Multidimensional flamelet-generated manifolds for partially premixed combustion

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Phuc-Danh; Vervisch, Luc; Subramanian, Vallinayagam; Domingo, Pascale [CORIA - CNRS and INSA de Rouen, Technopole du Madrillet, BP 8, 76801 Saint-Etienne-du-Rouvray (France)

2010-01-15

Flamelet-generated manifolds have been restricted so far to premixed or diffusion flame archetypes, even though the resulting tables have been applied to nonpremixed and partially premixed flame simulations. By using a projection of the full set of mass conservation species balance equations into a restricted subset of the composition space, unsteady multidimensional flamelet governing equations are derived from first principles, under given hypotheses. During the projection, as in usual one-dimensional flamelets, the tangential strain rate of scalar isosurfaces is expressed in the form of the scalar dissipation rates of the control parameters of the multidimensional flamelet-generated manifold (MFM), which is tested in its five-dimensional form for partially premixed combustion, with two composition space directions and three scalar dissipation rates. It is shown that strain-rate-induced effects can hardly be fully neglected in chemistry tabulation of partially premixed combustion, because of fluxes across iso-equivalence-ratio and iso-progress-of-reaction surfaces. This is illustrated by comparing the 5D flamelet-generated manifold with one-dimensional premixed flame and unsteady strained diffusion flame composition space trajectories. The formal links between the asymptotic behavior of MFM and stratified flame, weakly varying partially premixed front, triple-flame, premixed and nonpremixed edge flames are also evidenced. (author)

Effect of mass-transport limitations on the performance of a packed bed membrane reactor for partial oxidations. Intraparticle mass transport

NARCIS (Netherlands)

Sint Annaland, van M.; Kurten, U.; Kuipers, J.A.M.

2007-01-01

For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the

Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Intraparticle Mass Transport

NARCIS (Netherlands)

van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

2007-01-01

For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the

Use of Interface Treatment to Reduce Emissions from Residuals in Lower Permeability Zones to Groundwater flowing Through More Permeable Zones (Invited)

Science.gov (United States)

Johnson, P.; Cavanagh, B.; Clifton, L.; Daniels, E.; Dahlen, P.

2013-12-01

Many soil and groundwater remediation technologies rely on fluid flow for contaminant extraction or reactant delivery (e.g., soil vapor extraction, pump and treat, in situ chemical oxidation, air sparging, enhanced bioremediation). Given that most unconsolidated and consolidated settings have permeability contrasts, the outcome is often preferential treatment of more permeable zones and ineffective treatment of the lower permeability zones. When this happens, post-treatment contaminant emissions from low permeability zone residuals can cause unacceptable long-term impacts to groundwater in the transmissive zones. As complete remediation of the impacted lower permeability zones may not be practicable with conventional technologies, one might explore options that lead to reduction of the contaminant emissions to acceptable levels, rather than full remediation of the lower permeability layers. This could be accomplished either by creating a sustained emission reaction/attenuation zone at the high-low permeability interface, or by creating a clean soil zone extending sufficiently far into the lower permeability layer to cause the necessary reduction in contaminant concentration gradient and diffusive emission. These options are explored in proof-of-concept laboratory-scale physical model experiments. The physical models are prepared with two layers of contrasting permeability and either dissolved matrix storage or nonaqueous phase liquid (NAPL) in the lower permeability layer. A dissolved oxidant is then delivered to the interface via flow across the higher permeability layer and changes in contaminant emissions from the low permeability zone are monitored before, during, and after oxidant delivery. The use of three oxidants (dissolved oxygen, hydrogen peroxide and sodium persulfate) for treatment of emissions from petroleum hydrocarbon residuals is examined.

A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions

International Nuclear Information System (INIS)

Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C.; Brooks, Scott C; Pace, Molly; Kim, Young Jin; Jardine, Philip M.; Watson, David B.

2007-01-01

This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M. partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M. species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing NE equilibrium reactions and a set of reactive transport equations of M-NE kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions

A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions.

Science.gov (United States)

Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C; Brooks, Scott C; Pace, Molly N; Kim, Young-Jin; Jardine, Philip M; Watson, David B

2007-06-16

This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing N(E) equilibrium reactions and a set of reactive transport equations of M-N(E) kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions.

The effect of mass transport on the graphite/CO2 reaction

International Nuclear Information System (INIS)

Stephen, W.J.

1984-11-01

The Graphite/CO 2 reaction is strongly inhibited by the reaction product CO and therefore any model for the influence of mass transport on reaction rate should consider this. The problem of internal mass transport alone has been considered in previous notes. This note extends the models to include external mass transport. Results are compared with simple first order reaction with no volume change. The calculations demonstrate that, for strong CO inhibition, external mass transport limits reaction at a much lower rate than for first order kinetics and that the usual concept of three reaction zones corresponding to chemical control, in-pore diffusion control and boundary layer control can be unrealistically idealised. (U.K.)

Mobility of partially molten crust, heat and mass transfer, and the stabilization of continents

Science.gov (United States)

Teyssier, Christian; Whitney, Donna L.; Rey, Patrice F.

2017-04-01

The core of orogens typically consists of migmatite terrains and associated crustal-derived granite bodies (typically leucogranite) that represent former partially molten crust. Metamorphic investigations indicate that migmatites crystallize at low pressure (cordierite stability) but also contain inclusions of refractory material (mafic, aluminous) that preserve evidence of crystallization at high pressure (HP), including HP granulite and eclogite (1.0-1.5 GPa), and in some cases ultrahigh pressure (2.5-3.0 GPa) when the continental crust was subducted (i.e. Norwegian Caledonides). These observations indicate that the partially molten crust originates in the deep crust or at mantle depths, traverses the entire orogenic crust, and crystallizes at shallow depth, in some cases at the near-surface ( 2 km depth) based on low-T thermochronology. Metamorphic assemblages generally show that this nearly isothermal decompression is rapid based on disequilibrium textures (symplectites). Therefore, the mobility of partially molten crust results in one of the most significant heat and mass transfer mechanisms in orogens. Field relations also indicate that emplacement of partially molten crust is the youngest major event in orogeny, and tectonic activity essentially ceases after the partially molten crust is exhumed. This suggests that flow and emplacement of partially molten crust stabilize the orogenic crust and signal the end of orogeny. Numerical modeling (open source software Underworld; Moresi et al., 2007, PEPI 163) provides useful insight into the mechanisms of exhumation of partially molten crust. For example, extension of thickened crust with T-dependent viscosity shows that extension of the shallow crust initially drives the mobility of the lowest viscosity crust (T>700°C), which begins to flow in a channel toward the zone of extension. This convergent flow generates channel collision and the formation of a double-dome of foliation (two subdomes separated by a steep

Microarray Cluster Analysis of Irradiated Growth Plate Zones Following Laser Microdissection

International Nuclear Information System (INIS)

Damron, Timothy A.; Zhang Mingliang; Pritchard, Meredith R.; Middleton, Frank A.; Horton, Jason A.; Margulies, Bryan M.; Strauss, Judith A.; Farnum, Cornelia E.; Spadaro, Joseph A.

2009-01-01

Purpose: Genes and pathways involved in early growth plate chondrocyte recovery after fractionated irradiation were sought as potential targets for selective radiorecovery modulation. Materials and Methods: Three groups of six 5-week male Sprague-Dawley rats underwent fractionated irradiation to the right tibiae over 5 days, totaling 17.5 Gy, and then were killed at 7, 11, and 16 days after the first radiotherapy fraction. The growth plates were collected from the proximal tibiae bilaterally and subsequently underwent laser microdissection to separate reserve, perichondral, proliferative, and hypertrophic zones. Differential gene expression was analyzed between irradiated right and nonirradiated left tibia using RAE230 2.0 GeneChip microarray, compared between zones and time points and subjected to functional pathway cluster analysis with real-time polymerase chain reaction to confirm selected results. Results: Each zone had a number of pathways showing enrichment after the pattern of hypothesized importance to growth plate recovery, yet few met the strictest criteria. The proliferative and hypertrophic zones showed both the greatest number of genes with a 10-fold right/left change at 7 days after initiation of irradiation and enrichment of the most functional pathways involved in bone, cartilage, matrix, or skeletal development. Six genes confirmed by real-time polymerase chain reaction to have early upregulation included insulin-like growth factor 2, procollagen type I alpha 2, matrix metallopeptidase 9, parathyroid hormone receptor 1, fibromodulin, and aggrecan 1. Conclusions: Nine overlapping pathways in the proliferative and hypertrophic zones (skeletal development, ossification, bone remodeling, cartilage development, extracellular matrix structural constituent, proteinaceous extracellular matrix, collagen, extracellular matrix, and extracellular matrix part) may play key roles in early growth plate radiorecovery.

Short-time home coming project in evacuation zone

International Nuclear Information System (INIS)

Tatsuzaki, Hideo

2011-01-01

Accident at Fukushima Daiichi Nuclear Power Plants (NPPs) forced neighboring residents to evacuate, and evacuation zone (20 km radius from NPPs) was defined as highly contaminated and designated as no-entry zones. Residents had been obliged to live a refugee life for a longer period than expected. Short-time home coming project was initiated according to their requests. They came to the meeting place called transfer place (20 - 30 km radius from NPPs), wore protective clothing and personal dosimeter with having drinking water and came home in evacuation zone with staffs by bus. Their healthcare management professionals were fully prepared for emergency. After collecting necessary articles at home within two hours, they returned to the meeting place by bus for screening and dressing, and went back to refuge house. If screening data were greater than 13 kcpm using GM counters, partial body decontamination had been conducted by wiping and if greater than 100 kcpm, whole body decontamination was requested but not conducted. Dose rate of residents and staffs was controlled less than 1 mSv, which was alarm level of personal dosimeter. Stable iodine was prepared but actually not used. (T. Tanaka)

Partial strands synthesizing leads to inevitable aborting and complicated products in consecutive polymerase chain reactions (PCRs)

Institute of Scientific and Technical Information of China (English)

LUO Rui; ZHANG DaMing

2007-01-01

Various abnormal phenomena have been observed during PCR so far. The present study performed a series of consecutive PCRs (including many rounds of re-amplification continuously) and found that the abortion of re-amplification was inevitable as long as a variety of complicated product appeared.The aborting stages varied, according to the lengths of targets. Longer targets reached the abortion earlier than the shorter ones, marked by appearance of the complex that was immobile in electrophoresis. Denatured gel-electrophoresis revealed that the complex was mainly made up of shorter or partially synthesized strands, together with small amounts of full-length ones. Able to be digested by S1 nuclease but unable by restriction endonucleases (REs), the complex was proved to consist of both single regions and double-helix regions that kept the complex stable thermodynamically. Simulations gave evidence that partial strands, even at lower concentration, could disturb re-amplification effectively and lead to the abortion of re-amplifications finally. It was pointed out that the partial strands formed chiefly via polymerase's infidelity, and hence the solution to lighten the abnormality was also proposed.

Spontaneous Hedonic Reactions to Social Media Cues.

Science.gov (United States)

van Koningsbruggen, Guido M; Hartmann, Tilo; Eden, Allison; Veling, Harm

2017-05-01

Why is it so difficult to resist the desire to use social media? One possibility is that frequent social media users possess strong and spontaneous hedonic reactions to social media cues, which, in turn, makes it difficult to resist social media temptations. In two studies (total N = 200), we investigated less-frequent and frequent social media users' spontaneous hedonic reactions to social media cues using the Affect Misattribution Procedure-an implicit measure of affective reactions. Results demonstrated that frequent social media users showed more favorable affective reactions in response to social media (vs. control) cues, whereas less-frequent social media users' affective reactions did not differ between social media and control cues (Studies 1 and 2). Moreover, the spontaneous hedonic reactions to social media (vs. control) cues were related to self-reported cravings to use social media and partially accounted for the link between social media use and social media cravings (Study 2). These findings suggest that frequent social media users' spontaneous hedonic reactions in response to social media cues might contribute to their difficulties in resisting desires to use social media.

Correlation functions for fully or partially state-resolved reactive scattering calculations

International Nuclear Information System (INIS)

Manthe, Uwe; Welsch, Ralph

2014-01-01

Flux correlation functions and the quantum transition state concept are important tools for the accurate description of polyatomic reaction processes. Combined with the multi-configurational time-dependent Hartree approach, they facilitate rigorous full-dimensional calculations of cumulative and initial-state selected reaction probabilities for six atom reactions. In recent work [R. Welsch, F. Huarte-Larrañaga, and U. Manthe, J. Chem. Phys. 136, 064117 (2012)], an approach which allows one to calculate also state-to-state reaction probabilities within the quantum transition state concept has been introduced. This article presents further developments. Alternative generalized flux correlation functions are introduced and discussed. Equations for the calculation of fully state-resolved differential cross section using arbitrary definitions of the body fixed frame are derived. An approach for the efficient calculation of partially state-resolved observables as a function of the collision energy is introduced. Finally, numerical test studying the D + H 2 reaction illustrate important aspects of the formalism

Examination and experimental constraints of the stellar reaction rate factor N-A of the Ne-18(alpha, p)Na-21 reaction at temperatures of x-ray bursts

NARCIS (Netherlands)

Matic, A.; Mohr, P.

2013-01-01

The Ne-18(alpha, p)Na-21 reaction is one key for the breakout from the hot CNO cycles to the rp-process. Recent papers have provided reaction rate factors N-A which are discrepant by at least one order of magnitude. The compatibility of the latest experimental results is tested, and a partial

Metallogeny of subduction zones

Directory of Open Access Journals (Sweden)

Sorokhtin N. O.

2017-03-01

Full Text Available The paper deals with the multistage mechanism of the Earth's crust enrichment in ore elements in underthrust zones. The processes of metamorphism and the formation of hydrothermal solutions at pulling of the watered oceanic lithospheric plate into the subduction zone have been described. Some physical and chemical transformation regularities of structural-material complexes in these areas and mechanisms of the formation of ore deposits have been discussed. Spatio-temporal patterns of the localization of a number of endogenetic and exogenetic deposits have been described using metallogeny of the Ural and the Verkhoyansk-Kolyma Fold Belts as an example. It has been shown that in nature there are several effective mechanisms of the enrichment of the crust in ore minerals. One of them is the process of pulling into subduction zone of metalliferous sediments and ferromanganese crusts as well as seabed nodules, their metamorphic transformation, partial melting and transition of ore components into magmatic melts and mineralized fluids. In the future this leads to the release of ore material by magmas and hydrothermal solutions into the folded formations of island-arc and Andean types and the formation of igneous, metasomatic and hydrothermal deposits. Another, yet no less powerful natural mechanism of a conveyor enrichment of the crust in ore elements is the process of destruction and sedimentation of mineral deposits formed in the folded areas as well as the formation of placers and their transfer to the marginal parts of the continent. Later, during the collision of active and passive margins of two lithospheric plates, such as the collision of the Kolyma Massif with the eastern part of the Siberian craton in the middle of the Mesozoic there was a thrusting of a younger lithospheric plate over a more ancient one. As a result, the sedimentary sequences of the passive margin of the Siberian plate were submerged and partially melted by the basic magmas

SXPS investigation of the Cd partial electrolyte treatment of CuInSe2 absorbers

International Nuclear Information System (INIS)

Hunger, R.; Schulmeyer, T.; Klein, A.; Jaegermann, W.; Lebedev, M.V.; Sakurai, K.; Niki, S.

2005-01-01

The chemical modification of polycrystalline CuInSe 2 absorber surfaces by the so-called Cd partial electrolyte (PE) treatment was studied by synchrotron X-ray photoelectron spectroscopy (SXPS). The Cd PE treatment was found to remove surface indium oxides and hydroxides and segregated sodium compounds. A hydroxide-terminated CdSe surface layer of one monolayer thickness is formed by the partial electrolyte treatment. The reaction mechanism is discussed as substrate site-controlled exchange reaction, where surface indium is removed and replaced by cadmium. Electronically, the Cd PE treated surface is inverted and exhibits a surface barrier which is by 0.2 eV higher than a comparable structure that was prepared by the vacuum deposition of one monolayer of CdS onto clean CuInSe 2

Vadose zone studies at an industrial contaminated site: the vadose zone monitoring system and cross-hole geophysics

Science.gov (United States)

Fernandez de Vera, Natalia; Beaujean, Jean; Jamin, Pierre; Nguyen, Frédéric; Dahan, Ofer; Vanclooster, Marnik; Brouyère, Serge

2014-05-01

installed in two slanted boreholes on site, together with four vertical boreholes containing electrodes for geophysical measurements. Currently the site is being monitored under natural recharge conditions. Initial results show the reaction of the vadose zone to rainfall events, as well as chemical evolution of soil water with depth.

Energy balance and flow in steam generator part with sodium-water reaction

International Nuclear Information System (INIS)

Matal, O.

1980-01-01

Relations were derived for the calculation of heat liberated during the sodium water reaction in a tube failure in different parts of a steam generator. The results are graphically shown in i-T diagrams. Heat removal is described from the reaction zone to water and steam in undisturbed tubes and to the steam generator metal structure. (author)

Reaction scheme of partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia

NARCIS (Netherlands)

Zhu, J.J.; van Ommen, J.G.; Lefferts, Leonardus

2004-01-01

The partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia (YSZ) was studied with in situ FTIR and both steady-state and transient experiments. The four major products, CO, H2, CO2, and H2O, are primary products of CPOM over YSZ. Besides these major products and traces of

Fault zone architecture, San Jacinto fault zone, southern California: evidence for focused fluid flow and heat transfer in the shallow crust

Science.gov (United States)

Morton, N.; Girty, G. H.; Rockwell, T. K.

2011-12-01

We report results of a new study of the San Jacinto fault zone architecture in Horse Canyon, SW of Anza, California, where stream incision has exposed a near-continuous outcrop of the fault zone at ~0.4 km depth. The fault zone at this location consists of a fault core, transition zone, damage zone, and lithologically similar wall rocks. We collected and analyzed samples for their bulk and grain density, geochemical data, clay mineralogy, and textural and modal mineralogy. Progressive deformation within the fault zone is characterized by mode I cracking, subsequent shearing of already fractured rock, and cataclastic flow. Grain comminution advances towards the strongly indurated cataclasite fault core. Damage progression towards the core is accompanied by a decrease in bulk and grain density, and an increase in porosity and dilational volumetric strain. Palygorskite and mixed-layer illite/smectite clay minerals are present in the damage and transition zones and are the result of hydrolysis reactions. The estimated percentage of illite in illite/smectite increases towards the fault core where the illite/smectite to illite conversion is complete, suggesting elevated temperatures that may have reached 150°C. Chemical alteration and elemental mass changes are observed throughout the fault zone and are most pronounced in the fault core. We conclude that the observed chemical and mineralogical changes can only be produced by the interaction of fractured wall rocks and chemically active fluids that are mobilized through the fault zone by thermo-pressurization during and after seismic events. Based on the high element mobility and absence of illite/smectite in the fault core, we expect that greatest water/rock ratios occur within the fault core. These results indicate that hot pore fluids circulate upwards through the fractured fault core and into the surrounding damage zone. Though difficult to constrain, the site studied during this investigation may represent the top

Effect of imaginary part of an optical potential on reaction total cross sections

International Nuclear Information System (INIS)

Afanas'ev, G.N.; Dobromyslov, M.B.; Kim Yng Pkhung; Shilov, V.M.

1977-01-01

The effect of the imaginary part of optical potential on the total cross sections of reactions is explained. The complex rectangular well model is used, i.e. the real rectangular well at r 16 O + 27 Al reactions and the partial permeabilities are presented. It is demonstrated that the S-matrix has proved to be unitary. Oscillations of the partial permeabilities and cross-sections are observed for small potential values in the Wsub(o) imaginary part, which no longer occur at larger Wsub(o). This corresponds to the overlapping and nonoverlapping quasistationary levels in complex rectangular well

Conceptual Model of Uranium in the Vadose Zone for Acidic and Alkaline Wastes Discharged at the Hanford Site Central Plateau

Energy Technology Data Exchange (ETDEWEB)

Truex, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Szecsody, James E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Qafoku, Nikolla [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Serne, R. Jeffrey [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-09-01

Historically, uranium was disposed in waste solutions of varying waste chemistry at the Hanford Site Central Plateau. The character of how uranium was distributed in the vadose zone during disposal, how it has continued to migrate through the vadose zone, and the magnitude of potential impacts on groundwater are strongly influenced by geochemical reactions in the vadose zone. These geochemical reactions can be significantly influenced by the disposed-waste chemistry near the disposal location. This report provides conceptual models and supporting information to describe uranium fate and transport in the vadose zone for both acidic and alkaline wastes discharged at a substantial number of waste sites in the Hanford Site Central Plateau. The conceptual models include consideration of how co-disposed acidic or alkaline fluids influence uranium mobility in terms of induced dissolution/precipitation reactions and changes in uranium sorption with a focus on the conditions near the disposal site. This information, when combined with the extensive information describing uranium fate and transport at near background pH conditions, enables focused characterization to support effective fate and transport estimates for uranium in the subsurface.

Modeling the reactions catalyzed by coenzyme B12-dependent enzymes.

Science.gov (United States)

Sandala, Gregory M; Smith, David M; Radom, Leo

2010-05-18

Enzymes accelerate chemical reactions with an exceptional selectivity that makes life itself possible. Understanding the factors responsible for this efficient catalysis is of utmost importance in our quest to harness the tremendous power of enzymes. Computational chemistry has emerged as an important adjunct to experimental chemistry and biochemistry in this regard, because it provides detailed insights into the relationship between structure and function in a systematic and straightforward manner. In this Account, we highlight our recent high-level theoretical investigations toward this end in studying the radical-based reactions catalyzed by enzymes dependent on coenzyme B(12) (or adenosylcobalamin, AdoCbl). In addition to their fundamental position in biology, the AdoCbl-dependent enzymes represent a valuable framework within which to understand Nature's method of efficiently handling high-energy species to execute very specific reactions. The AdoCbl-mediated reactions are characterized by the interchange of a hydrogen atom and a functional group on adjacent carbon atoms. Our calculations are consistent with the conclusion that the main role of AdoCbl is to provide a source of radicals, thus moving the 1,2-rearrangements onto the radical potential energy surface. Our studies also show that the radical rearrangement step is facilitated by partial proton transfer involving the substrate. Specifically, we observe that the energy requirements for radical rearrangement are reduced dramatically with appropriate partial protonation or partial deprotonation or sometimes (synergistically) both. Such interactions are particularly relevant to enzyme catalysis, because it is likely that the local amino acid environment in the active site of an enzyme can function in this capacity through hydrogen bonding. Finally, our calculations indicate that the intervention of a very stable radical along the reaction pathway may inactivate the enzyme, demonstrating that sustained

Partial strands synthesizing leads to inevitable aborting and complicated products in consecutive polymerase chain reactions (PCRs)

Institute of Scientific and Technical Information of China (English)

2007-01-01

Various abnormal phenomena have been observed during PCR so far. The present study performed a series of consecutive PCRs (including many rounds of re-amplification continuously) and found that the abortion of re-amplification was inevitable as long as a variety of complicated product appeared. The aborting stages varied, according to the lengths of targets. Longer targets reached the abortion earlier than the shorter ones, marked by appearance of the complex that was immobile in electropho-resis. Denatured gel-electrophoresis revealed that the complex was mainly made up of shorter or partially synthesized strands, together with small amounts of full-length ones. Able to be digested by S1 nuclease but unable by restriction endonucleases (REs), the complex was proved to consist of both single regions and double-helix regions that kept the complex stable thermodynamically. Simulations gave evidence that partial strands, even at lower concentration, could disturb re-amplification effec- tively and lead to the abortion of re-amplifications finally. It was pointed out that the partial strands formed chiefly via polymerase’s infidelity, and hence the solution to lighten the abnormality was also proposed.

Petrography study on altered flint aggregate by alkali-silica reaction

International Nuclear Information System (INIS)

Bulteel, D.; Rafai, N.; Degrugilliers, P.; Garcia-Diaz, E.

2004-01-01

The aim of our study is to improve our understanding of an alkali-silica reaction (ASR) via petrography. We used a chemical concrete subsystem: flint aggregate, portlandite and KOH. The altered flint aggregate is followed by optical microscopy and scanning electron microscopy (SEM) before and after acid treatment at different intervals. After acid treatment, the observations showed an increase in aggregate porosity and revealed internal degradation of the aggregate. This degradation created amorphous zones. Before acid treatment, the analyses on polished sections by scanning electron microscopy coupled with energy dispersive spectroscopy (EDS) enabled visualization of K + and Ca 2+ penetration into the aggregate. The appearance of amorphous zones and penetration of positive ions into the aggregate are correlated with the increase in the molar fraction of silanol sites. This degradation is specific to the alkali-silica reaction

Electrochemical promotion of catalytic reactions with Pt/C (or Pt/Ru/C)//PBI catalysts

DEFF Research Database (Denmark)

Petrushina, Irina; Bjerrum, Niels; Bandur, Viktor

2007-01-01

The paper is an overview of the results of the investigation on electrochemical promotion of three catalytic reactions: methane oxidation with oxygen, NO reduction with hydrogen at 135 degrees C and Fischer-Tropsch synthesis (FTS) at 170 degrees C in the [CH4/O-2(or NO/H-2 or CO/H-2)/Ar//Pt(or Pt....../Ru)//PBI(H3PO4)/H-2, Ar] fuel cell. It has been shown that the partial methane oxidation to C2H2 and the C-2 selectivity were electrochemically promoted by the negative catalyst polarization. This was also the case in NO reduction with hydrogen for low NO and H-2 partial pressures. In both cases the catalytic...... reactions have been promoted by the electrochemically produced hydrogen. It has been found that the NO reduction with hydrogen on the Pt/PBI strongly depends on NO and hydrogen partial pressures in the working gas mixture. At higher NO and H-2 partial pressures the catalysis is promoted...

Implications of loading/unloading a subduction zone with a heterogeneously coupled interface

Science.gov (United States)

Herman, M. W.; Furlong, K. P.; Govers, R. M. A.

2017-12-01

Numerical models of subduction zones with appropriate physical properties may help understand deformation throughout great earthquake cycles, as well as associated observations such as the distribution of smaller magnitude megathrust earthquakes and surface displacements. Of particular interest are displacements near the trench, where tsunamis are generated. The patterns of co-seismic strain release in great megathrust earthquakes depend on the frictional coupling of the plate interface prior to the event. Geodetic observations during the inter-seismic stage suggest that the plates are fully locked at asperities surrounded by zones of apparent partial coupling. We simulate the accumulation (and release) of elastic strain in the subduction system using a finite element model with a relatively simple geometry and material properties. We demonstrate that inter-seismic apparent partial coupling can be dominantly explained by a distribution of completely locked asperities and zero friction elsewhere. In these models, the interface up-dip of the locked zone (displacements with little internal strain, potentially leading to large co-seismic block displacements (low displacement gradients) of the near-trench seafloor like those observed following the 2011 Mw 9.0 Tohoku earthquake. This is also consistent with anomalously low co-seismic frictional heating of the shallow megathrust indicated by borehole heat flow measurements after the Tohoku event. Our models also yield insights into slip partitioning throughout multiple earthquake cycles. In smaller ruptures, fault slip is inhibited by nearby locked zones; in subsequent multi-segment ruptures, the rest of this slip deficit may be released, producing significantly larger slip than might be expected based on historical earthquake magnitudes. Finally, because low-friction areas around asperities accumulate some slip deficit but may not rupture co-seismically, these regions may be the primary locations of afterslip following

Linear-stability theory of thermocapillary convection in a model of float-zone crystal growth

Science.gov (United States)

Neitzel, G. P.; Chang, K.-T.; Jankowski, D. F.; Mittelmann, H. D.

1992-01-01

Linear-stability theory has been applied to a basic state of thermocapillary convection in a model half-zone to determine values of the Marangoni number above which instability is guaranteed. The basic state must be determined numerically since the half-zone is of finite, O(1) aspect ratio with two-dimensional flow and temperature fields. This, in turn, means that the governing equations for disturbance quantities will remain partial differential equations. The disturbance equations are treated by a staggered-grid discretization scheme. Results are presented for a variety of parameters of interest in the problem, including both terrestrial and microgravity cases.

Accurate numerical simulation of reaction-diffusion processes for heavy oil recovery

Energy Technology Data Exchange (ETDEWEB)

Govind, P.A.; Srinivasan, S. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Texas Univ., Austin, TX (United States)

2008-10-15

This study evaluated a reaction-diffusion simulation tool designed to analyze the displacement of carbon dioxide (CO{sub 2}) in a simultaneous injection of carbon dioxide and elemental sodium in a heavy oil reservoir. Sodium was used due to the exothermic reaction of sodium with in situ that occurs when heat is used to reduce oil viscosity. The process also results in the formation of sodium hydroxide that reduces interfacial tension at the bitumen interface. A commercial simulation tool was used to model the sodium transport mechanism to the reaction interface through diffusion as well as the reaction zone's subsequent displacement. The aim of the study was to verify if the in situ reaction was able to generate sufficient heat to reduce oil viscosity and improve the displacement of the heavy oil. The study also assessed the accuracy of the reaction front simulation tool, in which an alternate method was used to model the propagation front as a moving heat source. The sensitivity of the simulation results were then evaluated in relation to the diffusion coefficient in order to understand the scaling characteristics of the reaction-diffusion zone. A pore-scale simulation was then up-scaled to grid blocks. Results of the study showed that when sodium suspended in liquid CO{sub 2} is injected into reservoirs, it diffuses through the carrier phase and interacts with water. A random walk diffusion algorithm with reactive dissipation was implemented to more accurately characterize reaction and diffusion processes. It was concluded that the algorithm modelled physical dispersion while neglecting the effect of numerical dispersion. 10 refs., 3 tabs., 24 figs.

Earthquakes, fluid pressures and rapid subduction zone metamorphism

Science.gov (United States)

Viete, D. R.

2013-12-01

High-pressure/low-temperature (HP/LT) metamorphism is commonly incomplete, meaning that large tracts of rock can remain metastable at blueschist- and eclogite-facies conditions for timescales up to millions of years [1]. When HP/LT metamorphism does take place, it can occur over extremely short durations (the role of fluids in providing heat for metamorphism [2] or catalyzing metamorphic reactions [1]. Earthquakes in subduction zone settings can occur to depths of 100s of km. Metamorphic dehydration and the associated development of elevated pore pressures in HP/LT metamorphic rocks has been identified as a cause of earthquake activity at such great depths [3-4]. The process of fracturing/faulting significantly increases rock permeability, causing channelized fluid flow and dissipation of pore pressures [3-4]. Thus, deep subduction zone earthquakes are thought to reflect an evolution in fluid pressure, involving: (1) an initial increase in pore pressure by heating-related dehydration of subduction zone rocks, and (2) rapid relief of pore pressures by faulting and channelized flow. Models for earthquakes at depth in subduction zones have focussed on the in situ effects of dehydration and then sudden escape of fluids from the rock mass following fracturing [3-4]. On the other hand, existing models for rapid and incomplete metamorphism in subduction zones have focussed only on the effects of heating and/or hydration with the arrival of external fluids [1-2]. Significant changes in pressure over very short timescales should result in rapid mineral growth and/or disequilibrium texture development in response to overstepping of mineral reaction boundaries. The repeated process of dehydration-pore pressure development-earthquake-pore pressure relief could conceivably produce a record of episodic HP/LT metamorphism driven by rapid pressure pulses. A new hypothesis is presented for the origins of HP/LT metamorphism: that HP/LT metamorphism is driven by effective pressure

Mushy Zone Properties and Castability of Aluminium Foundry Alloys

Energy Technology Data Exchange (ETDEWEB)

Dahle, A.K.

1996-01-01

The growing application and market share of aluminium castings demand better understanding of the mechanisms of defect formation during casting. Although casting is a cost-effective production route, inadequate reproducibility and quality of the cast structure often restrict the utilization of castings. This doctoral thesis aims to (1) determine how the solidification conditions affect the rheological behaviour in the partially solidified state, (2) to measure how alterations in solidification variables influence castability, and (3) to investigate the relationship between mushy zone rheology and castability. The development of mechanical strength in the mushy zone was measured as a function of chemical composition. Measurements of the dendrite coherency point provided accurate determination of the point where the dendrite network is established. The strength measurements confirm that the dendrites are largely independent and free-floating before dendrite coherency. The point and rate of strength development in the subsequently established interdendritic network strongly depend on the size and morphology of the dendrites and fraction solid. The castability investigation was limited to evaluations of fluidity and feeding. Fluidity measurements showed a complex effect of increased grain refinement. Alterations of the concentration and type of main alloying element gave a direct relationship between mushy zone rheology and fluidity. The range of the operating feeding mechanisms during solidification is directly related to the rheological properties of the mushy zone. 251 refs., 77 refs., 25 tabs.

Effect of percolation rate on water-travel time in deep, partially saturated zones

International Nuclear Information System (INIS)

Peters, R.R.; Gauthier, J.H.; Dudley, A.L.

1986-02-01

The Nevada Nuclear Waste Storage Investigations (NNWSI) project is investigating Yucca Mountain, Nye county, Nevada, as a prospective site for a radioactive-waste repository. The Yucca Mountain site is unique among those currently being investigated by the US Department of Energy (DOE) in that the prospective repository location is in the unsaturated zone, approximately 300 m above the water table. The rock units at Yucca Mountain can be grouped into three types: (1) vitric tuffs with high matrix conductivity and few fractures; (2) zeolitized tuffs with low matrix conductivity and few fractures; and (3) densely welded tuffs with low matrix conductivities and many fractures. The prospective repository zone is in densely welded tuff; the units between it and the water table are of types 1 and 2. Current percolation rates through Yucca Mountain, and those that are currently postulated under future climatic conditions, are thought to be of the order of the saturated matrix conductivity of some of the units. Although it is probable that there is now little or no water movement in fracture, it is necessary to investigate the potential for fracture flow, especially that which could be initiated under future climatic conditions. Significant fracture flow, if present, could reduce the water travel time between the repository and the water table. A composite-porosity, continuum model was developed to model flow in a fractured, porous medium. Simulations using data from the Yucca Mountain site and this model in the one-dimensional code TOSPAC indicate that current estimates of the percolation rate result in water movement confined to the matrix and that the water-travel time from the repository to the water table is on the order of hundreds of thousands of years. this result is sensitive to the percolation rate; an increase in percolation rate of a factor of 10 many initiate water movement in the fractures, reducing the travel time significantly

Li-atoms-induced structure changes of Guinier–Preston–Bagaryatsky zones in AlCuLiMg alloys

Energy Technology Data Exchange (ETDEWEB)

Duan, S.Y.; Le, Z.; Chen, Z.K.; Gao, Z. [Center for High-Resolution Electron Microscopy, College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Chen, J.H., E-mail: jhchen123@hnu.edu.cn [Center for High-Resolution Electron Microscopy, College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Advanced Research Center, Central South University, Changsha 410083 (China); Ming, W.Q.; Li, S.Y.; Wu, C.L. [Center for High-Resolution Electron Microscopy, College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Yan, N. [Advanced Research Center, Central South University, Changsha 410083 (China)

2016-11-15

Guinier–Preston–Bagaryatsky (GPB) zones are the well-known strengthening precipitates of AlCuMg alloys formed upon thermal ageing. Here we report that when formed in AlCuLiMg alloys the GPB zones can change significantly in morphology and structure. It is shown that though they do still consist of Al, Cu and Mg elements fundamentally, the GPB zones in AlCuLiMg alloys have a rather different structure due to a featured Li-segregation at their interfaces with the matrix and possible Li-replacement of partial Mg atoms in the structure. As such the Li-containing GPB zones often develop from one-dimensional to quasi-two-dimensional precipitates. - Highlights: • We observe Guinier–Preston–Bagaryatsky zone variants in AlCuLiMg alloys. • We obtain atomic-resolution images of the precipitates and model their structures. • Li-atoms play a key role in modifying the structure of these precipitate variants.

Startup and operating characteristics of an external air-lift reflux partial nitritation-ANAMMOX integrative reactor.

Science.gov (United States)

Li, Xiang; Huang, Yong; Yuan, Yi; Bi, Zhen; Liu, Xin

2017-08-01

The differences in the physiological characteristics between AOB and ANAMMOX bacteria lead to suboptimal performance when used in a single reactor. In this study, aerobic and anaerobic zones with different survival environments were constructed in a single reactor to realize partitioned culture of AOB and ANAMMOX bacteria. An external air-lift reflux system was formed which used the exhaust from the aeration zone as power to return the effluent to the aeration zone. The reflux system effectively alleviated the large pH fluctuations and promoted NO 2 - -N to rapidly use by ANAMMOX bacteria, effectively inhibiting the activity of NOB. After 95d of running, the nitrogen removal rate increased from the initial 0.21kg/(m 3 ·d) to 3.1kg/(m 3 ·d). FISH analyses further demonstrated that AOB and ANAMMOX bacteria acquired efficient enrichment in the corresponding zone. Thus, this type of integrative reactor may create the environments needed for the partial nitritation-ANAMMOX processing. Copyright © 2017 Elsevier Ltd. All rights reserved.

IODP expedition 334: An investigation of the sedimentary record, fluid flow and state of stress on top of the seismogenic zone of an erosive subduction margin

Digital Repository Service at National Institute of Oceanography (India)

Vannucchi, P.; Ujiie, K.; Stroncik, N.; IODP Exp. 334 Scientific Party; Yatheesh, V.

permeable horizons in the upper plate may record reactions occurring at greater depths in the subduction zone and can be used to constrain reactions occurring within the seismogenic zone (Vannucchi et al., 2010). Based on the first results obtained during... of modified seawater in the igneous basement could be identified. Whereas pore fluids in the uppermost ~50 m at all sites drilled during Exp. 334 were dominated by reactions associated with the cycling of organic carbon, deep fluid flow was also detected...

Automated spectral zones selection methodology for diffusion theory data preparation for pebble bed reactor analysis

Science.gov (United States)

Mphahlele, Ramatsemela

A methodology is developed for the determination of the optimum spectral zones in Pebble Bed Reactors (PBR). In this work a spectral zone is defined as a zone made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. In other words the spectral zones are the regions over which the few-group diffusion parameters are generated. The identification of spectral boundaries is treated as an optimization problem. It is solved by systematically and simultaneously repositioning all zone boundaries to achieve the global minimum error between the reference transport solution (MCNP) and the diffusion code solution (NEM). The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates error in each zone. An iterative determination of group-dependent bucklings is incorporated into the methodology to properly account for spectral effects of neighboring zones. A preferred energy group structure has also been chosen. This optimization approach with the reference transport solution has proved to be accurate and consistent, however the computational effort required to complete the optimization process is significant. Thus a more practical methodology is also developed for the determination of the spectral zones in PBRs. The reactor physics characteristics of the spectral zones have been studied to understand the nature of the spectral zone boundaries. The practical tool involves the use of spectral indices based on few-group diffusion theory whole core calculations. With this methodology, there is no need to first have a reference transport solution. It is shown that the diffusion-theory coarse group fluxes and the effective multiplication factor computed using zones based on the practical index agrees within a narrow tolerance with those of the reference approach. Therefore the "practical" index

Fuel processor integrated H{sub 2}S catalytic partial oxidation technology for sulfur removal in fuel cell power plants

Energy Technology Data Exchange (ETDEWEB)

Gardner, T.H.; Berry, D.A.; Lyons, K.D.; Beer, S.K.; Freed, A.D. [U.S. Department of Energy, Morgantown, WV (USA). National Energy Technology Laboratory

2002-12-01

H{sub 2}S catalytic partial oxidation technology with an activated carbon catalyst was found to be a promising method for the removal of hydrogen sulfide from fuel cell hydrocarbon feedstocks. Three different fuel cell feedstocks were considered for analysis: sour natural gas, sour effluent from a liquid middle distillate fuel processor and a Texaco O{sub 2}-blown coal-derived synthesis gas. The H{sub 2}S catalytic partial oxidation reaction, its integratability into fuel cell power plants with different hydrocarbon feedstocks and its salient features are discussed. Experimental results indicate that H{sub 2}S concentration can be removed down to the part-per-million level in these plants. Additionally, a power law rate expression was developed and reaction kinetics compared to prior literature. The activation energy for this reaction was determined to be 34.4 kJ/g mol with the reaction being first order in H{sub 2}S and 0.3 order in O{sub 2}. 18 refs., 14 figs., 3 tabs.

Persulfate injection into a gasoline source zone

Science.gov (United States)

Sra, Kanwartej S.; Thomson, Neil R.; Barker, Jim F.

2013-07-01

One pore volume of unactivated sodium persulfate was delivered into an emplaced gasoline residual source zone at CFB Borden. Concentrations of inorganic species (S2O82 -, SO42 -, Na+, dissolved inorganic carbon (DIC)) and selected gasoline compounds (benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene) were monitored across a transect equipped with 90 multilevel sampling points for > 10 months post-injection. Mass loading (M˙) of compounds constructed from the transect data was used for assessment purposes. Breakthrough of inorganic species was observed when the injection slug crossed the monitoring transect. An increase in M indicated persulfate consumption during oxidation of gasoline compounds or degradation due to the interaction with aquifer materials. M increased by > 100% suggesting some mineralization of gasoline compounds during treatment. Mass loading for all the monitored gasoline compounds reduced by 46 to 86% as the inorganic slug crossed the monitoring transect. The cumulative mass discharge across the monitoring transect was 19 to 58% lower than that expected without persulfate injection. After the inorganic injection slug was flushed from the source zone a partial rebound (40 to 80% of baseline levels) of mass discharge of the monitored gasoline compounds was observed. The ensemble of data collected provides insight into the fate and transport of the injected persulfate solution, and the accompanying treatment of a gasoline the source zone.

On the long run effects of market splitting: Why more price zones might decrease welfare

International Nuclear Information System (INIS)

Grimm, Veronika; Martin, Alexander; Weibelzahl, Martin; Zöttl, Gregor

2016-01-01

In liberalized electricity markets we observe different approaches to congestion management. While nodal pricing is implemented in Canada and some markets in the United States, European markets are split up into a limited number of price zones with uniform prices, in order to at least partially realize the benefits of regional price differentiation. Zonal boundaries often coincide with national borders, but some countries are also split into multiple zones. In this paper we shed light on possible negative welfare effects of market splitting that arise in a model where investment incentives in new generation capacity are taken into account if zones are misspecified. We show that standard approaches to configure price zones – on the basis of projected nodal price differences or congested transmission capacity – may fail to suggest reasonable zone specifications. Also an adjustment of Available Transfer Capacities (ATCs) between zones or a switch to flow-based market splitting does not ensure positive welfare effects. Our analysis suggests that a careful and detailed evaluation of the system is needed to ensure a reasonable zone configuration. - Highlights: •We analyze investment and production in energy only markets with market splitting. •Market splitting can lead to decreased welfare even for reasonably chosen zones. •We identify the reasons for the negative impact of introducing prices zones.

Fracture toughness of partially welded joints of SUS316 stainless steel at 4 K by large bend tests

International Nuclear Information System (INIS)

Nishimura, A.; Tobler, R.L.; Tamura, H.; Imagawa, S.; Mito, T.; Yamamoto, J.; Motojima, O.; Takahashi, H.; Suzuki, S.

1996-01-01

Austenitic stainless steels in relatively thick sections are specified in support structure designs for huge superconducting magnets in fusion energy machines such as the Large Helical Device (LHD). In the LHD under construction at the National Institute for Fusion Science (NIFS) in Japan, partial welding of SUS 316 stainless steel is employed to fabricate the 100-mm thick coil can and coil support structures. Partial welding lowers the heat input and reduces residual deformation after welding. The main disadvantage is that a sizable crack-like defect remains embedded in the unwelded portion of the primary structural component. Here, SUS 316 stainless steel bars were partially welded and tested in 3-point bending to evaluate the effect of natural cracks on fusion zone toughness at 4 K. The specimens had a cross-section 87.5 mm x 175 mm and were fractured in liquid helium using a 10 MN cryogenic mechanical testing machine. In two tests, unstable fracture occurred at maximum load and at critical stress intensity factors K max = 227 and 228 MPa√m. Results indicate a high resistance to fracture initiation but no stable tearing. Therefore, no resistance to crack propagation may exist in a fusion zone at a weld root under cryogenic temperature

Carbon-coated magnetic palladium: applications in partial oxidation of alcohols and coupling reactions.

Science.gov (United States)

Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; catalyst can be used for oxidation of alcohols, amination reaction and arylation of aryl halides (cross coupli...

Cast Partial Denture versus Acrylic Partial Denture for Replacement of Missing Teeth in Partially Edentulous Patients

Directory of Open Access Journals (Sweden)

Pramita Suwal

2017-03-01

Full Text Available Aim: To compare the effects of cast partial denture with conventional all acrylic denture in respect to retention, stability, masticatory efficiency, comfort and periodontal health of abutments. Methods: 50 adult partially edentulous patient seeking for replacement of missing teeth having Kennedy class I and II arches with or without modification areas were selected for the study. Group-A was treated with cast partial denture and Group-B with acrylic partial denture. Data collected during follow-up visit of 3 months, 6 months, and 1 year by evaluating retention, stability, masticatory efficiency, comfort, periodontal health of abutment. Results: Chi-square test was applied to find out differences between the groups at 95% confidence interval where p = 0.05. One year comparison shows that cast partial denture maintained retention and stability better than acrylic partial denture (p< 0.05. The masticatory efficiency was significantly compromising from 3rd month to 1 year in all acrylic partial denture groups (p< 0.05. The comfort of patient with cast partial denture was maintained better during the observation period (p< 0.05. Periodontal health of abutment was gradually deteriorated in all acrylic denture group (p

Thermal transport in phononic crystals: The role of zone folding effect

Science.gov (United States)

Dechaumphai, Edward; Chen, Renkun

2012-04-01

Recent experiments [Yu et al., Nature Nanotech 5, 718 (2010); Tang et al., Nano Lett. 10, 4279 (2010); Hopkins etal., Nano Lett. 11, 107(2011)] on silicon based nanoscale phononic crystals demonstrated substantially reduced thermal conductivity compared to bulk Si, which cannot be explained by incoherent phonon boundary scattering within the Boltzmann Transport Equation (BTE). In this paper, partial coherent treatment of phonons, where phonons are regarded as either wave or particles depending on their frequencies, was considered. Phonons with mean free path smaller than the characteristic size of phononic crystals are treated as particles and the transport in this regime is modeled by BTE with phonon boundary scattering taken into account. On the other hand, phonons with mean free path longer than the characteristic size are treated as waves. In this regime, phonon dispersion relations are computed using the Finite Difference Time Domain (FDTD) method and are found to be modified due to the zone folding effect. The new phonon spectra are then used to compute phonon group velocity and density of states for thermal conductivity modeling. Our partial coherent model agrees well with the recent experimental results on in-plane thermal conductivity of phononic crystals. Our study highlights the importance of zone folding effect on thermal transport in phononic crystals.

Interface reactions between Pd thin films and SiC by thermal annealing and SHI irradiation

Energy Technology Data Exchange (ETDEWEB)

Njoroge, E.G., E-mail: eric.njoroge@up.ac.za [Department of Physics, University of Pretoria, Pretoria (South Africa); Theron, C.C. [Department of Physics, University of Pretoria, Pretoria (South Africa); Skuratov, V.A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Wamwangi, D. [School of Physics, University of Witwatersrand, Johannesburg (South Africa); Hlatshwayo, T.T. [Department of Physics, University of Pretoria, Pretoria (South Africa); Comrie, C.M. [MRD, iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa); Malherbe, J.B. [Department of Physics, University of Pretoria, Pretoria (South Africa)

2016-03-15

The solid-state reactions between Pd thin films and 6H-SiC substrates induced by thermal annealing, room temperature swift heavy ion (SHI) irradiation and high temperature SHI irradiation have been investigated by in situ and real-time Rutherford backscattering spectrometry (RBS) and Grazing incidence X-ray diffraction (GIXRD). At room temperature, no silicides were detected to have formed in the Pd/SiC samples. Two reaction growth zones were observed in the samples annealed in situ and analysed by real time RBS. The initial reaction growth region led to formation of Pd{sub 3}Si or (Pd{sub 2}Si + Pd{sub 4}Si) as the initial phase(s) to form at a temperature of about 450 °C. Thereafter, the reaction zone did not change until a temperature of 640 °C was attained where Pd{sub 2}Si was observed to form in the reaction zone. Kinetic analysis of the initial reaction indicates very fast reaction rates of about 1.55 × 10{sup 15} at cm{sup −2}/s and the Pd silicide formed grew linear with time. SHI irradiation of the Pd/SiC samples was performed by 167 MeV Xe{sup 26+} ions at room temperature at high fluences of 1.07 × 10{sup 14} and 4 × 10{sup 14} ions/cm{sup 2} and at 400 °C at lower fluences of 5 × 10{sup 13} ions/cm{sup 2}. The Pd/SiC interface was analysed by RBS and no SHI induced diffusion was observed for room temperature irradiations. The sample irradiated at 400 °C, SHI induced diffusion was observed to occur accompanied with the formation of Pd{sub 4}Si, Pd{sub 9}Si{sub 2} and Pd{sub 5}Si phases which were identified by GIXRD analysis.

New results on the Roper resonance and the P-11 partial wave

NARCIS (Netherlands)

Sarantsev, A. V.; Fuchs, M.; Kotulla, M.; Thoma, U.; Ahrens, J.; Annand, J. R. M.; Anisovich, A. V.; Anton, G.; Bantes, R.; Bartholomy, O.; Beck, R.; Beloglazov, Yu.; Castelijns, R.; Crede, V.; Ehmanns, A.; Ernst, J.; Fabry, I.; Flemming, H.; Foesel, A.; Funke, Chr.; Gothe, R.; Gridnev, A.; Gutz, E.; Hoeffgen, St.; Horn, I.; Hoessl, J.; Hornidge, D.; Janssen, S.; Junkersfeld, J.; Kalinowsky, H.; Klein, F.; Klempt, E.; Koch, H.; Konrad, M.; Kopf, B.; Krusche, B.; Langheinrich, J.; Loehner, H.; Lopatin, I.; Lotz, J.; McGeorge, J. C.; MacGregor, I. J. D.; Matthaey, H.; Menze, D.; Messchendorp, J. G.; Metag, V.; Nikonov, V. A.; Novinski, D.; Novotny, R.; Ostrick, M.; van Pee, H.; Pfeiffer, M.; Radkov, A.; Rosner, G.; Rost, M.; Schmidt, C.; Schoch, B.; Suft, G.; Sumachev, V.; Szczepanek, T.; Walther, D.; Watts, D. P.; Weinheimer, Chr.

2008-01-01

Properties of the Roper resonance, the first scalar excitation of the nucleon, are determined. Pole positions and residues of the P-11 partial wave are studied in a combined analysis of pion- and photo-induced reactions. We find the Roper pole at {(1371 +/- 7) - i(92 +/- 10)} MeV and an elasticity

First measurement of 30S+α resonant elastic scattering for the 30S(α ,p ) reaction rate

Science.gov (United States)

Kahl, D.; Yamaguchi, H.; Kubono, S.; Chen, A. A.; Parikh, A.; Binh, D. N.; Chen, J.; Cherubini, S.; Duy, N. N.; Hashimoto, T.; Hayakawa, S.; Iwasa, N.; Jung, H. S.; Kato, S.; Kwon, Y. K.; Nishimura, S.; Ota, S.; Setoodehnia, K.; Teranishi, T.; Tokieda, H.; Yamada, T.; Yun, C. C.; Zhang, L. Y.

2018-01-01

Background: Type I x-ray bursts are the most frequently observed thermonuclear explosions in the galaxy, resulting from thermonuclear runaway on the surface of an accreting neutron star. The 30S(α ,p ) reaction plays a critical role in burst models, yet insufficient experimental information is available to calculate a reliable, precise rate for this reaction. Purpose: Our measurement was conducted to search for states in 34Ar and determine their quantum properties. In particular, natural-parity states with large α -decay partial widths should dominate the stellar reaction rate. Method: We performed the first measurement of 30S+α resonant elastic scattering up to a center-of-mass energy of 5.5 MeV using a radioactive ion beam. The experiment utilized a thick gaseous active target system and silicon detector array in inverse kinematics. Results: We obtained an excitation function for 30S(α ,α ) near 150∘ in the center-of-mass frame. The experimental data were analyzed with R -matrix calculations, and we observed three new resonant patterns between 11.1 and 12.1 MeV, extracting their properties of resonance energy, widths, spin, and parity. Conclusions: We calculated the resonant thermonuclear reaction rate of 30S(α ,p ) based on all available experimental data of 34Ar and found an upper limit about one order of magnitude larger than a rate determined using a statistical model. The astrophysical impact of these two rates has been investigated through one-zone postprocessing type I x-ray burst calculations. We find that our new upper limit for the 30S(α ,p )33Cl rate significantly affects the predicted nuclear energy generation rate during the burst.

Conservation-dissipation structure of chemical reaction systems.

Science.gov (United States)

Yong, Wen-An

2012-12-01

In this Brief Report, we show that balanced chemical reaction systems governed by the law of mass action have an elegant conservation-dissipation structure. From this structure a number of important conclusions can be easily deduced. In particular, with the help of this structure we can rigorously justify the classical partial equilibrium approximation in chemical kinetics.

PIERO ontology for analysis of biochemical transformations: effective implementation of reaction information in the IUBMB enzyme list.

Science.gov (United States)

Kotera, Masaaki; Nishimura, Yosuke; Nakagawa, Zen-ichi; Muto, Ai; Moriya, Yuki; Okamoto, Shinobu; Kawashima, Shuichi; Katayama, Toshiaki; Tokimatsu, Toshiaki; Kanehisa, Minoru; Goto, Susumu

2014-12-01

Genomics is faced with the issue of many partially annotated putative enzyme-encoding genes for which activities have not yet been verified, while metabolomics is faced with the issue of many putative enzyme reactions for which full equations have not been verified. Knowledge of enzymes has been collected by IUBMB, and has been made public as the Enzyme List. To date, however, the terminology of the Enzyme List has not been assessed comprehensively by bioinformatics studies. Instead, most of the bioinformatics studies simply use the identifiers of the enzymes, i.e. the Enzyme Commission (EC) numbers. We investigated the actual usage of terminology throughout the Enzyme List, and demonstrated that the partial characteristics of reactions cannot be retrieved by simply using EC numbers. Thus, we developed a novel ontology, named PIERO, for annotating biochemical transformations as follows. First, the terminology describing enzymatic reactions was retrieved from the Enzyme List, and was grouped into those related to overall reactions and biochemical transformations. Consequently, these terms were mapped onto the actual transformations taken from enzymatic reaction equations. This ontology was linked to Gene Ontology (GO) and EC numbers, allowing the extraction of common partial reaction characteristics from given sets of orthologous genes and the elucidation of possible enzymes from the given transformations. Further future development of the PIERO ontology should enhance the Enzyme List to promote the integration of genomics and metabolomics.

Improved solution for saturated-unsaturated flow to a partially penetrating well in a compressible unconfined aquifer

Science.gov (United States)

Mishra, P. K.; Neuman, S. P.

2009-12-01

Tartakovsky and Neuman [2007] developed an analytical solution for flow to a partially penetrating well pumping at a constant rate from a compressible unconfined aquifer considering an unsaturated zone of infinite thickness. In their solution three-dimensional, axially symmetric unsaturated flow was described by a linearized version of Richards’ equation in which both relative hydraulic conductivity and water content vary exponentially with incremental capillary pressure head relative to its air entry value. Both exponential functions were characterized by a common exponent. We present an improved solution in which relative hydraulic conductivity and water content are characterized by separate parameters and the unsaturated zone has finite thickness. Our four-parameter representation of these functions is more flexible than the three-parameter version of Mathias and Butler [2006], who consider flow in the unsaturated zone to be strictly vertical and the pumping well to be fully penetrating. We investigate the effects of unsaturated zone thickness and constitutive parameters on drawdown in the unsaturated and saturated zones as functions of position and time. We then use our new solution to analyze data from synthetic and real pumping tests.

A compartmentalized solute transport model for redox zones in contaminated aquifers: 1. Theory and development

Science.gov (United States)

Abrams , Robert H.; Loague, Keith

2000-01-01

This paper, the first of two parts [see Abrams and Loague, this issue], takes the compartmentalized approach for the geochemical evolution of redox zones presented by Abrams et al. [1998] and embeds it within a solute transport framework. In this paper the compartmentalized approach is generalized to facilitate the description of its incorporation into a solute transport simulator. An equivalent formulation is developed which removes any discontinuities that may occur when switching compartments. Rate‐limited redox reactions are modeled with a modified Monod relationship that allows either the organic substrate or the electron acceptor to be the rate‐limiting reactant. Thermodynamic constraints are used to inhibit lower‐energy redox reactions from occurring under infeasible geochemical conditions without imposing equilibrium on the lower‐energy reactions. The procedure used allows any redox reaction to be simulated as being kinetically limited or thermodynamically limited, depending on local geochemical conditions. Empirical reaction inhibition methods are not needed. The sequential iteration approach (SIA), a technique which allows the number of solute transport equations to be reduced, is adopted to solve the coupled geochemical/solute transport problem. When the compartmentalized approach is embedded within the SIA, with the total analytical concentration of each component as the dependent variable in the transport equation, it is possible to reduce the number of transport equations even further than with the unmodified SIA. A one‐dimensional, coupled geochemical/solute transport simulation is presented in which redox zones evolve dynamically in time and space. The compartmentalized solute transport (COMPTRAN) model described in this paper enables the development of redox zones to be simulated under both kinetic and thermodynamic constraints. The modular design of COMPTRAN facilitates the use of many different, preexisting solute transport and

Barium atoms and N20 molecular agregates reaction

International Nuclear Information System (INIS)

Visticot, J.P.; Mestdagh, J.M.; Alcaraz, C.; Cuvellier, J.; Berlande, J.

1988-06-01

The collisions between a barium atom and N20 molecular agregates are studied, for a better understanding of the solvation part in a chemical reaction. The experiments are carried out in a crossed molecular beam device. The light coming from the collision zone is scattered, and analysed by means of a photon detector. A time-of-flight technique is applied in the investigation of the beam's polymer concentration. The results show a nearly negligible chemiluminescent effect in the reaction between barium and N20 polymer. A solvated BaO formation mechanism is proposed to justify the experimental results [fr

Exact solutions of some coupled nonlinear diffusion-reaction ...

Indian Academy of Sciences (India)

certain coupled diffusion-reaction (D-R) equations of very general nature. In recent years, various direct methods have been proposed to find the exact solu- tions not only of nonlinear partial differential equations but also of their coupled versions. These methods include unified ansatz approach [3], extended hyperbolic func ...

Parapapillary atrophy: histological gamma zone and delta zone.

Directory of Open Access Journals (Sweden)

Jost B Jonas

Full Text Available BACKGROUND: To examine histomorphometrically the parapapillary region in human eyes. METHODOLOGY/PRINCIPAL FINDINGS: The histomorphometric study included 65 human globes (axial length:21-37 mm. On anterior-posterior histological sections, we measured the distance Bruch's membrane end (BME-optic nerve margin ("Gamma zone", BME-retinal pigment epithelium (RPE ("Beta zone", BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer. "Delta zone" was defined as part of gamma zone in which blood vessels of at least 50 µm diameter were not present over a length of >300 µm. Beta zone (mean length:0.35±0.52 mm was significantly (P = 0.01 larger in the glaucoma group than in the non-glaucomatous group. It was not significantly (P = 0.28 associated with axial length. Beta zone was significantly (P = 0.004 larger than the region with occluded choriocapillaris. Gamma zone (mean length:0.63±1.25 mm was associated with axial length (P50 µm diameter within gamma zone was present only in highly axially elongated globes and was not related with glaucoma. Beta zone (Bruch's membrane without RPE was correlated with glaucoma but not with globe elongation. Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.

Partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor

KAUST Repository

Zhang, Xuming

2015-01-01

We studied the relative importance of the reduced field intensity and the background reaction temperature in the partial oxidation of methane in a temperature-controlled dielectric barrier discharge reactor. We obtained important mechanistic insight from studying high-temperature and low-pressure conditions with similar reduced field intensities. In the tested range of background temperatures (297 < T < 773 K), we found that the conversion of methane and oxygen depended on both the electron-induced chemistry and the thermo-chemistry, whereas the chemical pathways to the products were overall controlled by the thermo-chemistry at a given temperature. We also found that the thermo-chemistry enhanced the plasma-assisted partial oxidation process. Our findings expand our understanding of the plasma-assisted partial oxidation process and may be helpful in the design of cost-effective plasma reformers. © 2014 The Combustion Institute.

Effects of deficit irrigation and partial root-zone drying on soil and plant water status, stomatal conductance, plant growth and water use efficiency in tomato during early fruiting stage

DEFF Research Database (Denmark)

Liu, Fulai; Shahnazari, Ali; Jacobsen, S.-E.

2008-01-01

The effects of 'partial root-zone drying' (PRD), compared with full irrigation (FI) and deficit irrigation (DI), on soil and plant water status, plant growth and water use efficiency (WUE) were investigated in potted tomatoes (Lycopersicon esculentum L., var. Cedrico) at the early fruiting stage...... system, and the irrigated side of the plants was reversed when volumetric soil water content ( ) of the dry side had decreased to 6%. of FI was about 14%. of DI decreased during the first 4-5 days after the onset of treatment (DAT) and was about 7% and 6% thereafter for DI-70 and DI-50, respectively....... of the wet side in PRD-70 declined during 3-6 DAT and was lower than that of FI by 4-6% thereafter. in both wet and dry sides of PRD-50 was slightly lower than that for PRD-70. After 5 DAT, midday leaf water potential was significantly lower in DI and PRD than in FI plants. FI plants had the highest leaf...

A field ion microscope study of the surface reaction of tungsten with n-octanol under an applied positive voltage: reaction conditions for the 'splitting' of (110) plane

International Nuclear Information System (INIS)

Terao, T.; Iwatsu, F.; Morikawa, H.

1993-01-01

Field ion microscopy is a powerful tool for the study of surface phenomena on an atomic scale, especially when they are crystal plane dependent, because the microscope shows many crystal planes of the sample tip simultaneously. Although a large number of FIM studies on vapor deposition, surface diffusion and surface reactions at a metal-gas interface have been reported, those on reactions at a metal-liquid interface are few. The authors have studied the corrosion or tungsten with aqueous solutions and found that water corroded the tungsten tips very severely to reduce the radius of curvature of the tip cap drastically. The reaction was so severe that it was not possible to trace it back to the very initial stages. They adopted, as a weaker reagent, one of the higher alcohols, n-octanol(C 8 H 17 OH), and found that it reacted with tungsten tips when an electrical pulse with a positive voltage between 5 and 10V was applied to the tip, giving very interesting field ion images in which the central (110) plane was divided into two parts located side by side across the [001] zone line. This means that some anisotropic surface reaction occurred which made a groove along the [001] zone line going through the (110) plane, usually the most stable plane chemically for bcc metals. They named this phenomenon 'splitting'. This reaction was less severe than that with water and some results on the morphology of the groove and on the reaction sequence have been reported. In the present paper more detailed reaction conditions which give rise to the splitting are described

Iteration scheme for implicit calculations of kinetic and equilibrium chemical reactions in fluid dynamics

International Nuclear Information System (INIS)

Ramshaw, J.D.; Chang, C.H.

1995-01-01

An iteration scheme for the implicit treatment of equilibrium chemical reactions in partial equilibrium flow has previously been described. Here we generalize this scheme to kinetic reactions as well as equilibrium reactions. This extends the applicability of the scheme to problems with kinetic reactions that are fast in regions of the flow field but slow in others. The resulting scheme thereby provides a single unified framework for the implicit treatment of an arbitrary number of coupled equilibrium and kinetic reactions in chemically reacting fluid flow. 10 refs., 2 figs

ERC Workshop on Geometric Partial Differential Equations

CERN Document Server

Novaga, Matteo; Valdinoci, Enrico

2013-01-01

This book is the outcome of a conference held at the Centro De Giorgi of the Scuola Normale of Pisa in September 2012. The aim of the conference was to discuss recent results on nonlinear partial differential equations, and more specifically geometric evolutions and reaction-diffusion equations. Particular attention was paid to self-similar solutions, such as solitons and travelling waves, asymptotic behaviour, formation of singularities and qualitative properties of solutions. These problems arise in many models from Physics, Biology, Image Processing and Applied Mathematics in general, and have attracted a lot of attention in recent years.

Hydrogen solubility in pore water of partially saturated argillites: Application to Callovo-Oxfordian clay-rock in the context of a nuclear waste geological disposal

International Nuclear Information System (INIS)

Lassin, A.; Dymitrowska, M.; Azaroual, M.

2011-01-01

In nuclear waste geological disposals, large amounts of hydrogen (H 2 ) are expected to be produced by different (bio-)geochemical processes. Depending on the pressure generated by such a process, H 2 could be produced as a gas phase and displace the neighbouring pore water. As a consequence, a water-unsaturated zone could be created around the waste and possibly affect the physical and physic-chemical properties of the disposal and the excavation disturbed zone around it. The present study is the first part of an ongoing research program aimed at evaluating the possible chemical evolution of the pore water-minerals-gas system in such a context. The goal of this study was to evaluate, in terms of thermodynamic equilibrium conditions, the geochemical disturbance of the pore water due to variations in hydrogen pressure, temperature and relative humidity. No heterogeneous reactions involving mineral phases of the clay-rock or reactive surface sites were taken into account in the thermodynamic analysis. In the case sulphate reduction reaction is allowed, geochemical modelling results indicate that the main disturbance is the increase in pH (from around 7 up to more than 10) and an important decrease in the redox potential (Eh) related to hydrogen dissolution. This occurs from relatively low H 2 partial pressures (∼1 bar and above). Then, temperature and relative humidity (expressed in terms of capillary pressure) further displace the thermodynamic equilibrium conditions, namely the pH and the aqueous speciation as well as saturation indices of mineral phases. Finally, the results suggest that the generation of hydrogen, combined with an increase in temperature (between 30 deg. C and 80 deg. C) and a decrease in relative humidity (from 100% to 30%), should increase the chemical reactivity of the pore water-rock-gas system. (authors)

Increased hydrazine during partial nitritation process in upflow air-lift reactor fed with supernatant of anaerobic digester effluent

Energy Technology Data Exchange (ETDEWEB)

Choi, Jeongdong [University of Alberta, Alberta (Canada); Jung, Sokhee [Samsung SDS, Seoul (Korea, Republic of); Ahn, Young-Ho [Yeungnam University, Gyungsan (Korea, Republic of)

2013-06-15

The optimal balance of ammonium and nitrite is essential for successful operation of the subsequent anammox process. We conducted a partial nitritation experiment using an upflow air-lift reactor to provide operational parameters for achieving the optimal ratio of ammonium to nitrite, by feeding supernatant of anaerobic digester effluent, high-nitrogen containing rejection water. Semi-continuous operation results show that HRT should be set between 15 and 17 hours to achieve the optimum ration of 1.3 of NO{sub 2}-N/NH{sub 4}-N. In the UAR, nitritation was the dominant reaction due to high concentration of ammonia and low biodegradable organics. The influent contained low concentrations of hydroxylamine and hydrazine. However, hydrazine increased during partial nitritation by ⁓60-130% although there was no potential anammox activity in the reactor. The partial nitritation process successfully provided the ratio of nitrogen species for the anammox reaction, and relived the nitrite restraint on the anammox activity by increasing hydrazine concentration.

Spin distribution in preequilibrium reactions for ⁴⁸Ti + n.

Energy Technology Data Exchange (ETDEWEB)

Dashdorj, Dugersuren [North Carolina State Univ., Raleigh, NC (United States)

2005-04-12

Cross section measurements were made of prompt γ-ray production as a function of incident neutron energy on a ⁴⁸Ti sample. Partial γ-ray cross sections for transitions in ^45-48Ti, ^44-48Sc, and ^42-45Ca have been determined. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the LANSCE/WNR facility. The prompt-reaction γ rays were detected with the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The γ-ray excitation functions were converted to partial γ-ray cross sections taking into account the dead-time correction, target thickness, detector efficiency and neutron flux (monitored with an in-line fission chamber). The data are presented for neutron energies E_n between 1 to 200 MeV. These results are compared with model calculations which include compound nuclear and pre-equilibrium emission. The model calculations are performed using the STAPRE reaction code for E_n up to 20 MeV and the GNASH reaction code for E_n up to 120 MeV. Using the GNASH reaction code the effect of the spin distribution in preequilibrium reactions has been investigated. The preequilibrium reaction spin distribution was calculated using the quantum mechanical theory of Feshbach, Kerman, and Koonin (FKK). The multistep direct (MSD) part of the FKK theory was calculated for a one-step process. The contribution from higher steps is estimated to be small. The spin distribution of the multistep compound (MSC) part of FKK theory is assumed to be the same as in the compound nucleus. The FKK preequilibrium spin distribution was incorporated into the GNASH calculations and the γ-ray production cross sections were calculated and compared with experimental data. The difference in the partial γ-ray cross sections using spin distributions with and without

Hydrogeological Modelling of the Geothermal Waters of Alaşehir in the Continental Rift Zone of the Gediz, Western Anatolia, Turkey

Science.gov (United States)

Ӧzgür, Nevzat; Bostancı, Yesim; Anilır Yürük, Ezgi

2017-12-01

In western Anatolia, Turkey, the continental rift zones of the Büyük Menderes, Küçük Menderes and Gediz were formed by extensional tectonic features striking E-W generally and representing a great number of active geothermal systems, epithermal mineralizations and volcanic rocks from Middle Miocene to recent. The geothermal waters are associated with the faults which strike preferentially NW-SE and NE-SW and locate diagonal to general strike of the rift zones of the Menderes Massif. These NW-SE and NE-SW striking faults were probably generated by compressional tectonic regimes which leads to the deformation of uplift between two extensional rift zones in the Menderes Massif. The one of these rift zones is Gediz which is distinguished by a great number of geothermal waters such as Alaşehir, Kurşunlu, Çamurlu, Pamukkale and Urganlı. The geothermal waters of Alaşehir form the biggest potential in the rift zone of Gediz with a capacity of about 100 to 200 MWe. Geologically, the gneisses from the basement rocks in the study area which are overlain by an Paleozoic to Mesozoic intercalation of mica schists, quartzites and marbles, a Miocene intercalation of conglomerates, sandstones and clay stones and Plio-Quaternary intercalation of conglomerates, sandstones and clay stones discordantly. In the study area, Paleozoic to Mesozoic quartzites and marbles form the reservoir rocks hydrogeologically. The geothermal waters anions with Na+K>Ca>Mg dominant cations and HCO3>Cl> dominant anions are of Na-HCO3 type and can be considered as partial equilibrated waters. According to the results of geochemical thermometers, the reservoir temperatures area of about 185°C in accordance with measured reservoir temperatures. Stabile isotopes of δ18O versus δ2H of geothermal waters of Alaşehir deviate from the meteoric water line showing an intensive water-rock interaction under high temperature conditions. These data are well correlated with the results of the

A simple one-step chemistry model for partially premixed hydrocarbon combustion

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Tarrazo, Eduardo [Instituto Nacional de Tecnica Aeroespacial, Madrid (Spain); Sanchez, Antonio L. [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, Leganes 28911 (Spain); Linan, Amable [ETSI Aeronauticos, Pl. Cardenal Cisneros 3, Madrid 28040 (Spain); Williams, Forman A. [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093-0411 (United States)

2006-10-15

This work explores the applicability of one-step irreversible Arrhenius kinetics with unity reaction order to the numerical description of partially premixed hydrocarbon combustion. Computations of planar premixed flames are used in the selection of the three model parameters: the heat of reaction q, the activation temperature T{sub a}, and the preexponential factor B. It is seen that changes in q with equivalence ratio f need to be introduced in fuel-rich combustion to describe the effect of partial fuel oxidation on the amount of heat released, leading to a universal linear variation q(f) for f>1 for all hydrocarbons. The model also employs a variable activation temperature T{sub a}(f) to mimic changes in the underlying chemistry in rich and very lean flames. The resulting chemistry description is able to reproduce propagation velocities of diluted and undiluted flames accurately over the whole flammability limit. Furthermore, computations of methane-air counterflow diffusion flames are used to test the proposed chemistry under nonpremixed conditions. The model not only predicts the critical strain rate at extinction accurately but also gives near-extinction flames with oxygen leakage, thereby overcoming known predictive limitations of one-step Arrhenius kinetics. (author)

Colloid-Facilitated Transport of Radionuclides through the Vadose Zone

International Nuclear Information System (INIS)

Flury, Markus; Harsh, James B.; Zachara, John M.; McCarthy, John F.; Lichtner, Peter C.

2006-01-01

This project seeks to improve the basic understanding of the role of colloids in facilitating the transport of contaminants in the vadose zone. We focus on three major thrusts: (1) thermodynamic stability and mobility of colloids formed by reactions of sediments with highly alkaline tank waste solutions, (2) colloid-contaminant interactions, and (3) in-situ colloid mobilization and colloid facilitated contaminant transport occurring in both contaminated and uncontaminated Hanford sediments

Development of a novel reactor concept for the partial oxidation of methane to syngas

NARCIS (Netherlands)

Smit, J.; van Sint Annaland, M.; Kuipers, J.A.M.

2004-01-01

The gas-to-liquid process, consisting of the partial oxidation of methane (POM) followed by the Fischer-Tropsch reaction, is a promising alternative to conventional oil processing for the production of liquid fuels. The cost of a conventional POM process is mainly determined by cryogenic air

Modelling of a reverse flow catalytic membrane reactor for the partial oxidation of methane

NARCIS (Netherlands)

Smit, J.; van Sint Annaland, M.; Kuipers, J.A.M.

2003-01-01

Gas-To-Liquid (GTL) processes have great potential as alternative to conventional oil and coal processing for the production of liquid fuels. In GTL-processes the partial oxidation of methane (POM) is combined with the Fischer-Tropsch reaction. An important part of the investment costs of a

Nuclear-waste isolation in the unsaturated zone of arid regions

International Nuclear Information System (INIS)

Wollenberg, H.A.; Wang, J.S.Y.; Korbin, G.

1982-05-01

The vadose zone in arid regions is considered as a possible environment for geologic isolation of nuclear waste. There are several topographic and lithologic combinations in the vadose zone of arid regions that may lend themselves to waste isolation considerations. In some cases, topographic highs such as mesas and interbasin ranges - comprised of several rock types, may contain essentially dry or partially saturated conditions favorable for isolation. The adjacent basins, especially in the far western and southwestern US, may have no surface or subsurface hydrologic connections with systems ultimately leading to the ocean. Some rock types may have the favorable characteristics of very low permeability and contain appropriate minerals for the strong chemical retardation of radionuclides. Environments exhibiting these hydrologic and geochemical attributes are the areas underlain by tuffaceous rocks, relatively common in the Basin and Range geomorphic province. Adjacent valley areas, where tuffaceous debris makes up a significant component of valley fill alluvium, may also contain thick zones of unsaturated material, and as such also lend themselves to strong consideration as respository environments. This paper summarizes the aspects of nuclear waste isolation in unsaturated regimes in alluvial-filled valleys and tuffaceous rocks of the Basin and Range province

Persulfate injection into a gasoline source zone.

Science.gov (United States)

Sra, Kanwartej S; Thomson, Neil R; Barker, Jim F

2013-07-01

One pore volume of unactivated sodium persulfate was delivered into an emplaced gasoline residual source zone at CFB Borden. Concentrations of inorganic species (S2O8(2-), SO4(2-), Na(+), dissolved inorganic carbon (DIC)) and selected gasoline compounds (benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene) were monitored across a transect equipped with 90 multilevel sampling points for >10months post-injection. Mass loading (M˙) of compounds constructed from the transect data was used for assessment purposes. Breakthrough of inorganic species was observed when the injection slug crossed the monitoring transect. An increase in [Formula: see text] indicated persulfate consumption during oxidation of gasoline compounds or degradation due to the interaction with aquifer materials. M˙DIC increased by >100% suggesting some mineralization of gasoline compounds during treatment. Mass loading for all the monitored gasoline compounds reduced by 46 to 86% as the inorganic slug crossed the monitoring transect. The cumulative mass discharge across the monitoring transect was 19 to 58% lower than that expected without persulfate injection. After the inorganic injection slug was flushed from the source zone a partial rebound (40 to 80% of baseline levels) of mass discharge of the monitored gasoline compounds was observed. The ensemble of data collected provides insight into the fate and transport of the injected persulfate solution, and the accompanying treatment of a gasoline the source zone. Copyright © 2013 Elsevier B.V. All rights reserved.

Highly stabilized partially premixed flames of propane in a concentric flow conical nozzle burner with coflow

KAUST Repository

Elbaz, Ayman M.

2018-01-11

Partially premixed turbulent flames with non-homogeneous jet of propane were generated in a concentric flow conical nozzle burner in order to investigate the effect of the coflow on the stability and flame structure. The flame stability is first mapped and then high-speed stereoscopic particle image velocimetry, SPIV, plus OH planar laser-induced fluorescence, OH-PLIF, measurements were conducted on a subset of four flames. The jet equivalence ratio Φ = 2, Jet exit Reynolds number Re = 10,000, and degree of premixing are kept constant for the selected flames, while the coflow velocity, Uc, is progressively changed from 0 to 15 m/s. The results showed that the flame is stable between two extinction limits of mixture inhomogeneity, and the optimum stability is obtained at certain degree of mixture inhomogeneity. Increasing Φ, increases the span between these two extinction limits, while these limits converge to a single point (corresponding to optimum mixture inhomogeneity) with increasing Re. Regardless the value of Φ, increasing the coflow velocity improves the flame stability. The correlation between recessed distance of the burner tubes and the fluctuation of the mixture fraction, Δξ, shows that at Δξ around 40% of the flammability limits leads to optimum flame stability. The time averaged SPIV results show that the coflow induces a big annular recirculation zone surrounds the jet flames. The size and the location of this zone is seen to be sensitive to Uc. However, the instantaneous images show the existence of a small vortical structure close to the shear layer, where the flame resides there in the case of no-coflow. These small vertical structures are seen playing a vital role in the flame structure, and increasing the flame corrugation close to the nozzle exit. Increasing the coflow velocity expands the central jet at the expense of the jet velocity, and drags the flame in the early flame regions towards the recirculation zone, where the flame tracks

A partial-wave analysis of the 3 pi system in the reaction K/sup -/p to pi /sup +/ pi /sup -/ pi /sup 0/ Lambda at 42 GeV/c

CERN Document Server

Cerrada, M; Chaloupka, V; Foster, B; Heinen, P M; Hemingway, R J; Holmgren, S O; Kittel, E W; Losty, Michael J; Massaro, G G G; Metzger, W J; Vergeest, J S M; Wagner, F; Wells, J; Wolters, G F

1977-01-01

A partial-wave analysis of the (3 pi )/sup 0/ system produced peripherally in the reaction K/sup -/p to pi /sup +/ pi /sup -/ pi /sup 0/ Lambda at 4.2 GeV/c is presented. The observation of the weak Lambda decay allows a determination of all the transverse production amplitudes except for two phases. The production of known resonances having decay modes other than 3 pi is used to test the isobar model ansatz. Significant omega (783), phi (1020) and A/sub 2/(1310) production is observed. The spin parity of the omega *(1675) is established as 3/sup -/. No evidence for production of other resonances, such as axial vector-mesons, is found. (23 refs).

Nutritional responses to soil drying and rewetting cycles under partial root-zone drying irrigation

DEFF Research Database (Denmark)

Wang, Yaosheng; Jensen, Christian Richardt; Liu, Fulai

2017-01-01

signaling that regulates stomatal aperture. PRI induced soil DRW cycles and more soil water dynamics in the root zone enhance soil nutrient mineralization process and thus increase the bioavailability of soil nutrients, resulting in improved nitrogen (N) and phosphorus (P) uptake, in which soil microbial...... processes play a key role. Studies investigating how soil DRW cycles and water dynamics under PRI on nutrient transport in soil solution, soil microbe mediated P transformation, interactions between phytohormones and nutrient uptake, root morphological and architectural traits for nutrient acquisition......Abstract Repeated soil drying and rewetting (DRW) cycles occur in rainfed and irrigated agriculture. The intensity and frequency of DRW cycles regulate both microbial physiology and soil physical processes, hereby affecting the mineralization and immobilization of soil nutrients...

Simulation of heat transfer in the unsaturated zone

International Nuclear Information System (INIS)

Zyvoloski, G.

1990-01-01

Heat transfer can play an important role in fluid flow near the emplacement site of high-level nuclear waste. The effects on far- field flow can be important in understanding net moisture fluxes above the repository zone. The convection in the unsaturated zone at the Yucca Mountain site was responsible for this movement. If this is so, then the convection could provide a mechanism for drying the rock above the repository zone and thus provide a buffer for heavy rainfall events. In addition, the convection would increase the movement of gaseous radionuclides such as 14 CO 2 , tritiated water vapor, and 129 I (Weeks, 1987). Because of the complexity of the problem, numerical models were required to calculate gas flow and vapor transport at the site. Kipp previously modeled this problem using the code HST3D. This code represents the flow of a single-phase fluid with both heat- and mass-transfer effects included. Water density and partial pressure effects are accounted for by the virtual temperature method. In this paper, the problem was simulated using the code FEHMN, a finite-element heat- and mass-transfer code being developed for the Yucca Mountain Project. The work described in this paper was done in preparation of the upcoming problem to be formulated for the Performance Assessment Calculation Exercise. 5 refs., 9 figs., 1 tab

Effect of percolation rate on water-travel time in deep, partially saturated zones

International Nuclear Information System (INIS)

Peters, R.R.; Gauthier, J.H.; Dudley, A.L.

1986-01-01

The Nevada Nuclear Waste Storage Investigations (NNWSI) project is investigating Yucca Mountain, Nye County, Nevada, as a prospective site for a radioactive-waste repository. The Yucca Mountain site is unique among those currently being investigated by the US Department of Energy (DOE) in that the prospective repository location is in the unsaturated zone, approximately 300 m above the water table. A composite-porosity, continuum model was developed to model flow in a fractured, porous medium. Simulations using data from the Yucca Mountain site and this model in the one-dimensional code TOSPAC indicate that current estimates of the percolation rate result in water movement confined to the matrix and that the water-travel time from the repository to the water table in on the order of hundreds of thousands of years. This result is sensitive to the percolation rate; an increase in percolation rate of a factor of 10 may initiate water movement in the fractures, reducing the travel time significantly

Effect of Mass Transport in the Synthesis of Partially Acetylated Dendrimer: Implications for Functional Ligand–Nanoparticle Distributions

OpenAIRE

Mullen, Douglas G.; Borgmeier, Emilee L.; Fang, Ming; McNerny, Daniel Q.; Desai, Ankur; Baker, James R.; Orr, Bradford G.; Holl, Mark M. Banaszak

2010-01-01

Partial acetylation of the amine-terminated poly(amidoamine) dendrimer has been used in the preparation of dendrimer particles conjugated with a wide variety of functional ligands including targeting moieties, therapeutic agents, and dye molecules. The effectiveness of mass transport during the partial acetylation reaction was found to have a major effect on subsequent distributions of dendrimer–ligand components and to be a major source of inconsistency between batches. This study has broad ...

Carbonation by fluid-rock interactions at high-pressure conditions: Implications for carbon cycling in subduction zones

Science.gov (United States)

Piccoli, Francesca; Vitale Brovarone, Alberto; Beyssac, Olivier; Martinez, Isabelle; Ague, Jay J.; Chaduteau, Carine

2016-07-01

Carbonate-bearing lithologies are the main carbon carrier into subduction zones. Their evolution during metamorphism largely controls the fate of carbon, regulating its fluxes between shallow and deep reservoirs. Recent estimates predict that almost all subducted carbon is transferred into the crust and lithospheric mantle during subduction metamorphism via decarbonation and dissolution reactions at high-pressure conditions. Here we report the occurrence of eclogite-facies marbles associated with metasomatic systems in Alpine Corsica (France). The occurrence of these marbles along major fluid-conduits as well as textural, geochemical and isotopic data indicating fluid-mineral reactions are compelling evidence for the precipitation of these carbonate-rich assemblages from carbonic fluids during metamorphism. The discovery of metasomatic marbles brings new insights into the fate of carbonic fluids formed in subducting slabs. We infer that rock carbonation can occur at high-pressure conditions by either vein-injection or chemical replacement mechanisms. This indicates that carbonic fluids produced by decarbonation reactions and carbonate dissolution may not be directly transferred to the mantle wedge, but can interact with slab and mantle-forming rocks. Rock-carbonation by fluid-rock interactions may have an important impact on the residence time of carbon and oxygen in subduction zones and lithospheric mantle reservoirs as well as carbonate isotopic signatures in subduction zones. Furthermore, carbonation may modulate the emission of CO2 at volcanic arcs over geological time scales.

Unfavorable surgical outcomes in partial epilepsy with secondary bilateral synchrony: Intracranial electroencephalography study.

Science.gov (United States)

Sunwoo, Jun-Sang; Byun, Jung-Ick; Moon, Jangsup; Lim, Jung-Ah; Kim, Tae-Joon; Lee, Soon-Tae; Jung, Keun-Hwa; Park, Kyung-Il; Chu, Kon; Kim, Manho; Chung, Chun-Kee; Jung, Ki-Young; Lee, Sang Kun

2016-05-01

Secondary bilateral synchrony (SBS) indicates bilaterally synchronous epileptiform discharges arising from a focal cortical origin. The present study aims to investigate SBS in partial epilepsy with regard to surgical outcomes and intracranial EEG findings. We retrospectively reviewed consecutive patients who underwent epilepsy surgery following extraoperative intracranial electroencephalography (EEG) study from 2008 to 2012. The presence of SBS was determined based upon the results of scalp EEG monitoring performed for presurgical evaluations. We reviewed scalp EEG, neuroimaging, intracranial EEG findings, and surgical outcomes in patients with SBS. We found 12 patients with SBS who were surgically treated for intractable partial epilepsy. Nine (75%) patients had lateralized ictal semiology and only two (16.6%) patients showed localized ictal onset in scalp EEG. Brain MRI showed epileptogenic lesion in three (25%) patients. Intracranial EEG demonstrated that ictal onset zone was widespread or non-localized in six (50%) patients. Low-voltage fast activity was the most common ictal onset EEG pattern. Rapid propagation of ictal onset was noted in 10 (83.3%) patients. Eleven patients underwent resective epilepsy surgery and only two patients (18.2%) achieved seizure-freedom (median follow-up 56 months). MRI-visible brain lesions were associated with favorable outcomes (p=0.024). Patients with SBS, compared to frontal lobe epilepsy without SBS, showed lesser localization in ictal onset EEG (p=0.029) and more rapid propagation during evolution of ictal rhythm (p=0.015). The present results suggested that resective surgery for partial epilepsy with SBS should be decided carefully, especially in case of nonlesional epilepsy. Poor localization and rapid spread of ictal onset were prominent in intracranial EEG, which might contribute to incomplete resection of the epileptogenic zone and poor surgical outcomes. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of non-reductive partial partitioning in FBR fuel reprocessing: a simulation study

International Nuclear Information System (INIS)

Shekhar Kumar; Koganti, S.B.

2002-06-01

The observed performance of conventional partitioning contactor in the Purex process in the Purex process is seldom satisfactory due to over-consumption of reductant and poor U-Pu decontamination factors. Contemporary trends indicate gradually move-over to MOX fuels for FBRs. In this scenario, it is not necessary to separate uranium and plutonium completely. By controlling the acid concentration and flow rates, it is possible to selectively strip essentially all the plutonium and part of the uranium in the aqueous stream. Therefore, a mixed product enriched in plutonium is obtained which can be precipitated and denitrated. Alternatively direct denitration by microwave heating can be used. The idea is particularly attractive for the flowsheet meant for the first core of FBTR where Pu/(U+Pu) ratio of 0.7 (in the discharged fuel) is diluted by addition of uranium to 0.3. By partial partitioning in the 2B contactor, a product enriched in plutonium (Pu/(U+Pu) ratio ∼0.6) can be obtained. After a minor uranium addition, this product will be suitable for the direct fabrication of II core of FBTR where a Pu/(U+Pu) ratio of 0.55 will be required. In a similar fashion, the enriched product can be used for multiple core zones of proposed PFBR by selective additions of uranium for each zone. To explore the feasibility of such partial partitioning step, an exhaustive simulation study was made using the in-house developed computer code SIMPSEX. 1300 simulations runs were completed for different combinations of parameters and results were analyzed. In this report, the results of this study and a possible flowsheet step have been discussed. Simultaneous variation in the flow rates has been considered and safe operating limits for the partial partitioning step have been established. (author)

Understanding Recreational Fishers' Compliance with No-take Zones in the Great Barrier Reef Marine Park

Directory of Open Access Journals (Sweden)

Adrian Arias

2013-12-01

Full Text Available Understanding fishers' compliance is essential for the successful management of marine protected areas. We used the random response technique (RRT to assess recreational fishers' compliance with no-take zones in the Great Barrier Reef Marine Park (GBRMP. The RRT allowed the asking of a sensitive question, i.e., "Did you, knowingly, fish within in a Green Zone during the last 12 months?" while protecting respondents' confidentiality. Application of the RRT through a survey of recreational fishers indicated that the majority of recreational fishers, 90%, comply with no-take zones. Likewise, most fishers, 92%, reported not personally knowing anyone who had intentionally fished in a no-take zone, indicating that fishers' perceive high levels of compliance among their peers. Fishers were motivated to comply with no-take zones primarily by their beliefs about penalties for noncompliance, followed by beliefs about the fishery benefits of no-take zones. Results suggest that compliance-related communication efforts by the managing authority have partially succeeded in maintaining appropriate compliance levels and that future efforts should accentuate normative compliance drivers that will encourage voluntary compliance. We conclude that compliance monitoring should be integrated into the adaptive management of the GBRMP and other protected areas; in this case social surveys using the RRT are effective tools.

Kinetic modelling of hydro-treatment reactions by study of different chemical groups; Modelisation cinetique des reactions d`hydrotraitement par regroupement en familles chimiques

Energy Technology Data Exchange (ETDEWEB)

Bonnardot, J

1998-11-19

Hydro-treatment of petroleum shortcuts permits elimination of unwanted components in order to increase combustion in engine and to decrease atmospheric pollution. Hydro-desulfurization (HDS), Hydro-denitrogenation (HDN) and Hydrogenation of aromatics (HDA) of a LCO (Light Cycle Oil)-Type gas oil have been studied using a new pilot at a fixed temperature with a NiMo/Al{sub 2}O{sub 3} catalyst. A hydrodynamic study showed that reactions occurring in the up-flow fixed bed reactor that has been used during the experiments, were governed exclusively by chemical reaction rates and not by diffusion. Through detailed chemical analysis, height chemical groups have been considered: three aromatics groups, one sulfided group, one nitrogenized and NH{sub 3}, H{sub 2}S, H{sub 2}. Two Langmuir-Hinshelwood-type kinetic models with either one or two types of sites have been established. The model with two types of site - one site of hydrogenation and one site of hydrogenolysis - showed a better fit in the modeling of the experimental results. This model enables to forecast the influence of partial pressure of H{sub 2}S and partial pressure of H{sub 2} on hydro-treatment reactions of a LCO-type gas oil. (author) 119 refs.

Modeling of pollutant formation in fully premixing surface burners using a verified practice-oriented experimental reaction-kinetic calculation method. Final report

International Nuclear Information System (INIS)

Ruy, C.; Kremer, H.

1996-01-01

The intent of the present study was to simulate quantitatively pollutant formation in premixing surface burners and to describe qualitatively the share of the premixing flame in pollut emissions from atmospheric burners. For this purpose reaction-kinetic programmes for one-dimensional premixing flames were extended by a terms describing heat discharge through gas radiation. Furthermore, the calculation range for the flame was extended far into the secondary reaction zone. Temperature, CO, and NO x profiles were measured in the secondary reaction zone of premixing burners at standard pressure. The air-fuel ratio was calculated within the practically relevant range between 0.5 and 1.5, as was load behaviour. (DG) [de

Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

Directory of Open Access Journals (Sweden)

Yuni Krisyuningsih Krisnandi

2015-11-01

Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

Study on Thixojoining Process Using Partial Remelting Method

Directory of Open Access Journals (Sweden)

M. N. Mohammed

2013-01-01

Full Text Available Cold-work tool steel is considered to be a nonweldable metal due to its high percentage content of carbon and alloy elements. The application of a new process of the semisolid joining of two dissimilar metals is proposed. AISI D2 cold-work tool steel was thixojoined to 304 stainless steel by using a partial remelting method. After thixojoining, microstructural examination including metallographic analysis, energy dispersive spectroscopy (EDS, and Vickers hardness tests was performed. From the results, metallographic analyses along the joint interface between semisolid AISI D2 and stainless steel showed a smooth transition from one to another and neither oxides nor microcracking was observed. Hardness values obtained from the points in the diffusion zone were much higher than those in the 304 stainless steel but lower than those in the AISI D2 tool steel. The study revealed that a new type of nonequilibrium diffusion interfacial structure was constructed at the interface of the two different types of steel. The current work successfully confirmed that avoidance of a dendritic microstructure in the semisolid joined zone and high bonding quality components can be achieved without the need for force or complex equipment when compared to conventional welding processes.

Recurrent Partial Words

Directory of Open Access Journals (Sweden)

Francine Blanchet-Sadri

2011-08-01

Full Text Available Partial words are sequences over a finite alphabet that may contain wildcard symbols, called holes, which match or are compatible with all letters; partial words without holes are said to be full words (or simply words. Given an infinite partial word w, the number of distinct full words over the alphabet that are compatible with factors of w of length n, called subwords of w, refers to a measure of complexity of infinite partial words so-called subword complexity. This measure is of particular interest because we can construct partial words with subword complexities not achievable by full words. In this paper, we consider the notion of recurrence over infinite partial words, that is, we study whether all of the finite subwords of a given infinite partial word appear infinitely often, and we establish connections between subword complexity and recurrence in this more general framework.

Transient MRI abnormalities associated with partial status epilepticus: a case report

Energy Technology Data Exchange (ETDEWEB)

Amato, Carmelo; Elia, Maurizio; Musumeci, Sebastiano A; Bisceglie, Pierluigi; Moschini, Massimo

2001-04-01

We report the case of an 18-year-old woman who presented a long-lasting cluster of partial seizures, and MRI cortical abnormalities localized in the left parietal lobe. The MRI changes correlated with the site of the epileptogenic focus, and disappeared within 2 weeks. The recognition of these reversible MRI abnormalities, which are presumably due to a temporary alteration of blood-brain barrier in the epileptogenic zone with subsequent edema, and are not associated with any underlying organic conditions, is extremely useful in the medical management of the patient and allows to avoid other invasive diagnostic procedures.

Transient MRI abnormalities associated with partial status epilepticus: a case report

International Nuclear Information System (INIS)

Amato, Carmelo; Elia, Maurizio; Musumeci, Sebastiano A.; Bisceglie, Pierluigi; Moschini, Massimo

2001-01-01

We report the case of an 18-year-old woman who presented a long-lasting cluster of partial seizures, and MRI cortical abnormalities localized in the left parietal lobe. The MRI changes correlated with the site of the epileptogenic focus, and disappeared within 2 weeks. The recognition of these reversible MRI abnormalities, which are presumably due to a temporary alteration of blood-brain barrier in the epileptogenic zone with subsequent edema, and are not associated with any underlying organic conditions, is extremely useful in the medical management of the patient and allows to avoid other invasive diagnostic procedures

Migratory and resident blue tits Cyanistes caeruleus differ in their reaction to a novel object

Science.gov (United States)

Nilsson, Anna L. K.; Nilsson, Jan-Åke; Alerstam, Thomas; Bäckman, Johan

2010-11-01

Individuals differ consistently in their behavioural reactions towards novel objects and new situations. Reaction to novelty is one part of a suit of individually consistent behaviours called coping strategies or personalities and is often summarised as bold or shy behaviour. Coping strategies could be particularly important for migrating birds exposed to novel environments on their journeys. We compared the average approach latencies to a novel object among migrants and residents in partially migratory blue tits Cyanistes caeruleus. In this test, we found migrating blue tits to have shorter approach latencies than had resident ones. Behavioural reactions to novelty can affect the readiness to migrate and short approach latency may have an adaptive value during migration. Individual behaviour towards novelty might be incorporated among the factors associated with migratory or resident behaviour in a partially migratory population.

Computer simulation for sodium-concrete reactions

International Nuclear Information System (INIS)

Zhang Bin; Zhu Jizhou

2006-01-01

In the liquid metal cooled fast breeder reactors (LMFBRs), direct contacts between sodium and concrete is unavoidable. Due to sodium's high chemical reactivity, sodium would react with concrete violently. Lots of hydrogen gas and heat would be released then. This would harm the ignorantly of the containment. This paper developed a program to simualte sodium-conrete reactions across-the-board. It could give the reaction zone temperature, pool temperature, penetration depth, penetration rate, hydrogen flux and reaction heat and so on. Concrete was considered to be composed of silica and water only in this paper. The variable, the quitient of sodium hydroxide, was introduced in the continuity equation to simulate the chemical reactions more realistically. The product of the net gas flux and boundary depth was ably transformed to that of penetration rate and boundary depth. The complex chemical kinetics equations was simplified under some hypothesises. All the technique applied above simplified the computer simulation consumedly. In other words, they made the computer simulation feasible. Theoretics models that applied in the program and the calculation procedure were expatiated in detail. Good agreements of an overall transient behavior were obtained in the series of sodium-concrete reaction experiment analysis. The comparison between the analytical and experimental results showed the program presented in this paper was creditable and reasonable for simulating the sodium-concrete reactions. This program could be used for nuclear safety judgement. (authors)

Method for sensing and measuring a concentration or partial pressure of a reactant used in a redox reaction

Science.gov (United States)

Findl, E.

1984-12-21

A method for sensing or measuring the partial pressure or concentration of an electroactive species used in conjunction with an electrolyte, the method being characterized by providing a constant current between an anode and a cathode of an electrolyte-containing cell, while measuring changes in voltage that occur between either the anode and cathode or between a reference electrode and one of the main electrodes of the cell, thereby to determine the concentration or partial pressure of the electro-active species as a function of said measured voltage changes. The method of the invention can be practiced using either a cell having only an anode and a cathode, or using a cell having an anode and a cathode in combination with a reference electrode. Accurate measurements of small concentrations or partial pressures of electro-active species are obtainable with the method of the invention, by using constant currents of only a few microamperes between the anode and cathode of the cell, while the concentration-determining voltage is measured.

The alkali-aggregate reaction - concrete microstructure evolution

International Nuclear Information System (INIS)

Regourd, M.; Hornain, H.; Poitevin, P.

1981-01-01

The alkali-aggregate reaction has been studied by scanning electron microscopy and energy dispersive X-ray analysis, electron probe microanalysis, and X-ray diffraction in concretes containing glass aggregates or hornfels and greywacke aggregates. The surface reaction of the natural aggregates in alkaline solutions has been analysed by X-ray photo-electron spectrometry. The study of concretes with glass aggregates stored at 20 degrees Celcius and 100 percent relative humidity has revealed, irrespective of alkali content and type of cement, the formation of a gel containing SiO 2 , Na 2 O, CaO, MgO and Al 2 O 3 . Under heat and pressure (210 degrees Celcius at MPa for 48 hours), the gel crystallizes and yields silicates not very different from tobermorite found in autoclaved normal concretes but cotaining Na and K in solid solutions. The alkali reaction in two natural aggregate concretes, is also shown by the formation of gels and silicate crystals. The progressive structuring of the gels in silicate crystals is promoted by an increase in temperature. Ettringite and Ca(OH) 2 reinforce the alkali-aggregate reaction which may be looked upon as a hydration reaction, partially of the pozzolanic type

New biphasic monocomponent composite material obtained by the partial oxypropylation of bacterial cellulose

International Nuclear Information System (INIS)

Rosa, Joyce Rover; Silva, Ingrid S.V. da; Pasquini, Daniel; Santos, Daniele B. dos; Barud, Hernane S.; Ribeiro, Sidney J.L.

2011-01-01

This study aimed to partial oxypropylation of bacterial cellulose (CB), as well as the characterization of pure CB, oxypropylated CB (CBO) and oxypropylated CB after Soxhlet extraction with hexane (CBOE). The oxypropylation reaction was carried out by propylene oxide polymerization, catalyzed by KOH, in the presence of CB The CB samples, before and after modification, were subjected to analysis of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was possible verify that the partial transformation of bacterial cellulose by inserting a layer of thermoplastic polymer on its surface occurred efficiently, obtaining a biphasic monocomponent composite material. (author)

A reworked Lake Zone margin: Chronological and geochemical constraints from the Ordovician arc-related basement of the Hovd Zone (western Mongolia)

Science.gov (United States)

Soejono, Igor; Buriánek, David; Janoušek, Vojtěch; Svojtka, Martin; Čáp, Pavel; Erban, Vojtěch; Ganpurev, Nyamtsetseg

2017-12-01

The primary relationships and character of the boundaries between principal lithotectonic domains in the Mongolian tract of the Central Asian Orogenic Belt (CAOB) are still poorly constrained. This brings much uncertainty in understanding of the orogeny configuration and the complete accretionary history. The plutonic Khuurai Tsenkher Gol Complex and the mainly metasedimentary Bij Group represent associated medium- to high-grade basement complexes exposed in the Hovd Zone close to its boundary with the Lake Zone in western Mongolia. The Khuurai Tsenkher Gol Complex is composed of variously deformed acid to basic magmatic rocks intimately associated with the metamorphosed sedimentary and volcanic rocks of the Bij Group. Results of our field work, new U-Pb zircon ages and whole-rock geochemical data suggest an existence of two separate magmatic events within the evolution of the Khuurai Tsenkher Gol Complex. Early to Mid-Ordovician (476 ± 5 Ma and 467 ± 4 Ma protoliths) normal- to high-K calc-alkaline orthogneisses, metadiorites and metagabbros predominate over Mid-Silurian (430 ± 3 Ma) tholeiitic-mildly alkaline quartz monzodiorites. Whereas the geochemical signature of the former suite unequivocally demonstrates its magmatic-arc origin, that of the latter quartz monzodiorite suggests an intra-plate setting. As shown by Sr-Nd isotopic data, the older arc-related magmas were derived from depleted mantle and/or were generated by partial melting of juvenile metabasic crust. Detrital zircon age populations of the metasedimentary rocks together with geochemical signatures of the associated amphibolites imply that the Bij Group was a volcano-sedimentary sequence, formed probably in the associated fore-arc wedge basin. Moreover, our data argue for an identical provenance of the Altai and Hovd domains, overall westward sediment transport during the Early Palaeozoic and the east-dipping subduction polarity. The obvious similarities of the Khuurai Tsenkher Gol Complex

Radiation protection zoning

International Nuclear Information System (INIS)

2015-01-01

Radiation being not visible, the zoning of an area containing radioactive sources is important in terms of safety. Concerning radiation protection, 2 work zones are defined by regulations: the monitored zone and the controlled zone. The ministerial order of 15 may 2006 settles the frontier between the 2 zones in terms of radiation dose rates, the rules for access and the safety standards in both zones. Radioprotection rules and the name of the person responsible for radiation protection must be displayed. The frontier between the 2 zones must be materialized and marked with adequate equipment (specific danger signs and tapes). Both zones are submitted to selective entrance, the access for the controlled zone is limited because of the radiation risk and of the necessity of confining radioactive contamination while the limitation of the access to the monitored zone is due to radiation risk only. (A.C.)

Design and operational procedures for ORC-based systems coupled with internal combustion engines driving electrical generators at full and partial load

International Nuclear Information System (INIS)

Badescu, Viorel; Aboaltabooq, Mahdi Hatf Kadhum; Pop, Horatiu; Apostol, Valentin; Prisecaru, Malina; Prisecaru, Tudor

2017-01-01

Highlights: • Waste heat recovery from Internal Combustion Engines (ICEs). • Organic Ranking Cycle (ORC) systems driving Electric Generators (EGs). • ICE-EG partial load operation. • Optimum design geometry of ORC system. • Optimum operation of ORC system at partial EG load. - Abstract: This paper refers to recovering waste heat from the hot gases exhausted by internal combustion engines (ICEs) driving electric generators (EGs) at full and partial load. The topic is of particular interest for developing countries where electric grids are underdeveloped or missing and electricity is generated locally by using classical fuels. The heat recovery system is based on an Organic Rankine Cycle (ORC). A novel method is proposed for the optimum design of ORC-based systems operating in combination with ICE at partial EG loads. First, ORC-based systems coupled with ICEs operating at full EG load is treated. Specific results for the operation at full EG load are as follows: (i) the optimum superheating increment ranges between 30 and 40 °C, depending on the type of the working fluids; (ii) a pinch point temperature difference exits between the flue gas temperature and the working fluid at the evaporator inlet; (iii) the total area of the evaporator is very close to the total area of the condenser, a fact which facilitates manufacturing; (iv) the surface area of the preheater zone is about 75% of the total surface area, while those of the boiler zone and superheater zone is about 13.5% and 11.5%, respectively. Second, the case of the ORC-based systems coupled with ICEs operating at partial EG load is considered. Specific results for this case are as follows: (v) the net power may be maximized by optimizing the working fluid mass flow rate; (vi) when the ICE is coupled with an ORC-based system, the overall thermal efficiency of the combined system, η ICE-ORC , is higher than the thermal efficiency of the ICE operating alone. As an example, for the case treated here, �

Flexural behaviour of partially bonded carbon fibre reinforced polymers strengthened concrete beams: Application to fire protection systems design

International Nuclear Information System (INIS)

Firmo, J.P.; Arruda, M.R.T.; Correia, J.R.; Tiago, C.

2015-01-01

Highlights: • The mechanical behaviour of partially bonded CFRP strengthened beams was modelled. • Two dimensional non-linear finite element models were developed. • Partially bonded beams can present similar flexural strength to fully bonded ones. • Relations between the bonded length and the strength reduction were proposed. • The proposed relations were used for the design of fire protection systems. - Abstract: Recent fire resistance tests on reinforced concrete (RC) beams strengthened with carbon fibre reinforced polymers (CFRP) laminates showed that it is possible to attain considerable fire endurance provided that thermal insulation is applied at the anchorage zones of the strengthening system. With such protection, although the CFRP laminate prematurely debonds in the central part of the beam, it transforms into a cable fixed at the extremities until one of the anchorage zones loses its bond strength. The main objective of this paper is to propose a simplified methodology for the design of fire protection systems for CFRP strengthened-RC beams, which is based on applying thicker insulation at the anchorage zones (promoting the above mentioned “cable behaviour”) and a thinner one at the current zone (avoiding tensile rupture of the carbon fibres). As a first step towards the validation of this methodology, finite element (FE) models were developed to simulate the flexural behaviour at ambient temperature of full-scale RC beams strengthened with CFRP laminates according to the externally bonded reinforcement (EBR) and near surface mounted (NSM) techniques, in both cases fully or partially bonded (the latter simulating the cable). The FE models were calibrated with results of 4-point bending tests on small-scale beams and then extended for different beam geometries, with spans (L) varying from 2 m to 5 m, in which the influence of the CFRP bonded length (l b ) and the loading type (point or uniformly distributed) on the strength reduction was

A fast exact sequential algorithm for the partial digest problem.

Science.gov (United States)

Abbas, Mostafa M; Bahig, Hazem M

2016-12-22

Restriction site analysis involves determining the locations of restriction sites after the process of digestion by reconstructing their positions based on the lengths of the cut DNA. Using different reaction times with a single enzyme to cut DNA is a technique known as a partial digestion. Determining the exact locations of restriction sites following a partial digestion is challenging due to the computational time required even with the best known practical algorithm. In this paper, we introduce an efficient algorithm to find the exact solution for the partial digest problem. The algorithm is able to find all possible solutions for the input and works by traversing the solution tree with a breadth-first search in two stages and deleting all repeated subproblems. Two types of simulated data, random and Zhang, are used to measure the efficiency of the algorithm. We also apply the algorithm to real data for the Luciferase gene and the E. coli K12 genome. Our algorithm is a fast tool to find the exact solution for the partial digest problem. The percentage of improvement is more than 75% over the best known practical algorithm for the worst case. For large numbers of inputs, our algorithm is able to solve the problem in a suitable time, while the best known practical algorithm is unable.

Intermediate energy charge-exchange reactions induced by polarized 3He

International Nuclear Information System (INIS)

Kim, B.T.

1998-01-01

Spin polarization transfer is proven to be very useful in obtaining detailed information of the continuum nuclear responses. The data, taken for the (vector p,vector n) reactions, have enabled us to separate the response into the spin longitudinal and transverse components. These partial nuclear responses have been successfully used to make critical tests of nuclear structure models. In the present paper, we first summarize the results of the data and the theoretical analyses made so far. We then discuss information obtainable from the ( 3 vector He,vector t) reaction, emphasizing on the differences and similarities in comparison with the (vector p,vector n) reaction. The results of numerical calculations made for ( 3 vector He,vector t) reactions based on the microscopic distorted wave impulse approximation will also be reported. (orig.)

Possibility of increasing the average rate of heterogeneous catalytic reactions by operating in the self-oscillating regime

Energy Technology Data Exchange (ETDEWEB)

Chumakov, G A; Slinko, M G

1979-05-01

The possibility of increasing the average rate of heterogeneous catalytic reactions by operating in the self-oscillating regime was demonstrated by analyzing a kinetic model of hydrogen interaction with oxygen over a metallic catalyst. Within a certain interval of partial pressures of oxygen, the average reaction rate over a period of oscillation may be over five times that of the steady-state reaction.

Response of herbaceous plant community diversity and composition to overstorey harvest within riparian management zones in Northern Hardwoods

Science.gov (United States)

Eric K. Zenner; Michelle A. Martin; Brian J. Palik; Jerilynn E. Peck; Charles R. Blinn

2013-01-01

Partial timber harvest within riparian management zones (RMZs) may permit active management of riparian forests while protecting stream ecosystems, but impacts on herbaceous communities are poorly understood. We compared herbaceous plant community abundance, diversity and composition in RMZs along small streams in northern Minnesota, USA, among four treatments before...

Quantification of Fault-Zone Plasticity Effects with Spontaneous Rupture Simulations

Science.gov (United States)

Roten, D.; Olsen, K. B.; Day, S. M.; Cui, Y.

2017-09-01

Previous studies have shown that plastic yielding in crustal rocks in the fault zone may impose a physical limit to extreme ground motions. We explore the effects of fault-zone non-linearity on peak ground velocities (PGVs) by simulating a suite of surface-rupturing strike-slip earthquakes in a medium governed by Drucker-Prager plasticity using the AWP-ODC finite-difference code. Our simulations cover magnitudes ranging from 6.5 to 8.0, three different rock strength models, and average stress drops of 3.5 and 7.0 MPa, with a maximum frequency of 1 Hz and a minimum shear-wave velocity of 500 m/s. Friction angles and cohesions in our rock models are based on strength criteria which are frequently used for fractured rock masses in civil and mining engineering. For an average stress drop of 3.5 MPa, plastic yielding reduces near-fault PGVs by 15-30% in pre-fractured, low strength rock, but less than 1% in massive, high-quality rock. These reductions are almost insensitive to magnitude. If the stress drop is doubled, plasticity reduces near-fault PGVs by 38-45% and 5-15% in rocks of low and high strength, respectively. Because non-linearity reduces slip rates and static slip near the surface, plasticity acts in addition to, and may partially be emulated by, a shallow velocity-strengthening layer. The effects of plasticity are exacerbated if a fault damage zone with reduced shear-wave velocities and reduced rock strength is present. In the linear case, fault-zone trapped waves result in higher near-surface peak slip rates and ground velocities compared to simulations without a low-velocity zone. These amplifications are balanced out by fault-zone plasticity if rocks in the damage zone exhibit low-to-moderate strength throughout the depth extent of the low-velocity zone (˜5 km). We also perform dynamic non-linear simulations of a high stress drop (8 MPa) M 7.8 earthquake rupturing the southern San Andreas fault along 250 km from Indio to Lake Hughes. Non-linearity in the

Mechanistic insights into the dehalogenation reaction of fluoroacetate/fluoroacetic acid

Science.gov (United States)

Miranda-Rojas, Sebastián; Toro-Labbé, Alejandro

2015-05-01

Fluoroacetate is a toxic compound whose environmental accumulation may represent an important contamination problem, its elimination is therefore a challenging issue. Fluoroacetate dehalogenase catalyzes its degradation through a two step process initiated by an SN2 reaction in which the aspartate residue performs a nucleophilic attack on the carbon bonded to the fluorine; the second step is hydrolysis that releases the product as glycolate. In this paper, we present a study based on density functional theory calculations of the SN2 initiation reaction modeled through the interaction between the substrate and the propionate anion as the nucleophile. Results are analyzed within the framework of the reaction force and using the reaction electronic flux to identify and characterize the electronic activity that drives the reaction. Our results reveal that the selective protonation of the substrate catalyzes the reaction by decreasing the resistance of the structural and electronic reorganization needed to reach the transition state. Finally, the reaction energy is modulated by the degree of stabilization of the fluoride anion formed after the SN2 reaction. In this way, a site-induced partial protonation acts as a chemical switch in a key process that determines the output of the reaction.

Origin of unusual fracture in stirred zone for friction stir welded 2198-T8 Al-Li alloy joints

Energy Technology Data Exchange (ETDEWEB)

Tao, Y. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ni, D.R., E-mail: drni@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xiao, B.L.; Ma, Z.Y. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wu, W.; Zhang, R.X. [AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China); Zeng, Y.S., E-mail: yszeng@hotmail.com [AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China)

2017-05-02

Friction stir welded (FSW) joints of conventional precipitation-hardened aluminum alloys usually fracture in the lowest hardness zone (LHZ) during tension testing. However, all of the FSW joints of a 2198-T8 Al-Li alloy fractured in the stirred zone (SZ) instead of the LHZ with the welding parameters of 800 rpm-200 mm/min and 1600 rpm-200 mm/min under the condition that no welding defects existed in the SZ. The experiment results revealed that lazy S was not the dominant factor resulting in the unusual fracture. The SZ consisted of three subzones, i.e., the shoulder-affected zone, the pin-affected zone, and the transition zone between them. While the former two zones were characterized by fine and equiaxed recrystallized grains, incompletely dynamically recrystallized microstructure containing coarse elongated non-recrystallized grains was observed in the transition zone. The transition zone exhibited the lowest average Taylor factor in the SZ, resulting in a region that was crystallographically weak. Furthermore, obvious lithium segregation at grain boundaries was observed in the transition zone via time-of-flight secondary ion mass spectroscopy analysis, but not in the shoulder-affected zone or the pin-affected zone. The combined actions of both the two factors resulted in the appearance of preferential intergranular fracture in the transition zone and eventually caused the failure in the SZ. The lithium segregation at grain boundaries in the transition zone was closely associated with both the segregation in the base material and the partially dynamically recrystallized microstructure resulting from the inhomogeneous plastic deformation in the SZ.

Origin of unusual fracture in stirred zone for friction stir welded 2198-T8 Al-Li alloy joints

International Nuclear Information System (INIS)

Tao, Y.; Ni, D.R.; Xiao, B.L.; Ma, Z.Y.; Wu, W.; Zhang, R.X.; Zeng, Y.S.

2017-01-01

Friction stir welded (FSW) joints of conventional precipitation-hardened aluminum alloys usually fracture in the lowest hardness zone (LHZ) during tension testing. However, all of the FSW joints of a 2198-T8 Al-Li alloy fractured in the stirred zone (SZ) instead of the LHZ with the welding parameters of 800 rpm-200 mm/min and 1600 rpm-200 mm/min under the condition that no welding defects existed in the SZ. The experiment results revealed that lazy S was not the dominant factor resulting in the unusual fracture. The SZ consisted of three subzones, i.e., the shoulder-affected zone, the pin-affected zone, and the transition zone between them. While the former two zones were characterized by fine and equiaxed recrystallized grains, incompletely dynamically recrystallized microstructure containing coarse elongated non-recrystallized grains was observed in the transition zone. The transition zone exhibited the lowest average Taylor factor in the SZ, resulting in a region that was crystallographically weak. Furthermore, obvious lithium segregation at grain boundaries was observed in the transition zone via time-of-flight secondary ion mass spectroscopy analysis, but not in the shoulder-affected zone or the pin-affected zone. The combined actions of both the two factors resulted in the appearance of preferential intergranular fracture in the transition zone and eventually caused the failure in the SZ. The lithium segregation at grain boundaries in the transition zone was closely associated with both the segregation in the base material and the partially dynamically recrystallized microstructure resulting from the inhomogeneous plastic deformation in the SZ.

A New Paradigm for Habitability in Planetary Systems: the Extremophilic Zone

Science.gov (United States)

Janot-Pacheco, E., Bernardes, L., Lage, C. A. S.

2014-03-01

More than a thousand exoplanets have been discovered so far. Planetary surface temperature may strongly depends on its albedo and geodynamic conditions. We have fed exoplanets from the Encyclopedia database with a comprehensive model of Earth's atmosphere and plate tectonics. As CO2 is the main agent responsible for the greenhouse effect, its partial pressure has been taken as a free parameter to estimate the surface temperature of some known planets. We also investigated the possible presence of "exomoons" belonging to giant planets in the Habitable Zone capable of harbour dynamic stability, to retain an atmosphere and to keep geodynamic activity for long time spans. Biological data on earthly micro-organisms classified as "extremophiles" indicate that such kind of microbial species could dwell on the surface of many exoplanets and exomoons. We thus propose an extension of the mainly astronomically defined "Habitable Zone" concept into the more astrobiologically one, the "Extremophililic Zone", that takes into account other parameters allowing survival of more robust life forms. This contribution comes from an ongoing project developed by a French-Brazilian colaboration in Astrophysics and Biophysics to search for living fingerprints in astrobiologically promising exoplanets.

Partial wave analysis of the reaction πN→Nππ and coupled channel analyses of the reactions πN in the CM energy range 1.38-1.74GeV

International Nuclear Information System (INIS)

Dolbeau, Jean.

1976-01-01

The partial wave analysis of 91314 π + -p→Nππ events at nine CM energies between 1.38 and 1.74GeV was performed using the generalized isobar model and assuming the coherent production of Δ, rho and sigma in the final state. A coupled channel analysis (K-matrix formalism) led to the determination of the arbitrary phase at each energy and to smooth the partial wave amplitudes. The paramaters (mass, total and partial widths, signs of coupling constants) of sixteen resonances, among which two new ones, are determined by two different methods. Those results help in classifying the lower-mass excited states of the nucleon in the frame of unitary symmetries, as SU6 [fr

Saturated-unsaturated flow to a partially penetrating well with storage in a compressible aquifer

Science.gov (United States)

Mishra, P. K.; Neuman, S. P.

2010-12-01

Mishra and Neuman [2010] developed an analytical solution for flow to a partially penetrating well of zero radius in a compressible unconfined aquifer that allows inferring its saturated and unsaturated hydraulic properties from responses recorded in the saturated and/or the unsaturated zone. We extend their solution to the case of a finite diameter pumping well with storage. Both solutions account for horizontal as well as vertical flows throughout the system. We investigate the effects of storage in the pumping well and delayed piezometer response on drawdowns in the saturated and unsaturated zones as functions of position and time; validate our solution against numerical simulations of drawdown in a synthetic aquifer having unsaturated properties described by the van Genuchten - Mualem constitutive model; and use our solution to analyze drawdown data from a pumping test conducted at the Borden site in Ontario, Canada.

Large Eddy Simulation of Sydney Swirl Non-Reaction Jets

DEFF Research Database (Denmark)

Yang, Yang; Kær, Søren Knudsen; Yin, Chungen

The Sydney swirl burner non-reaction case was studied using large eddy simulation. The two-point correlation method was introduced and used to estimate grid resolution. Energy spectra and instantaneous pressure and velocity plots were used to identify features in flow field. By using these method......, vortex breakdown and precessing vortex core are identified and different flow zones are shown....

The reaction kinetics of lithium salt with water vapor

International Nuclear Information System (INIS)

Balooch, M.; Dinh, L.N.; Calef, D.F.

2002-01-01

The interaction of lithium salt (LiH and/or LiD) with water vapor in the partial pressure range of 10 -5 -2657 Pa has been investigated. The reaction probability of water with LiH cleaved in an ultra high vacuum environment was obtained using the modulated molecular beam technique. This probability was 0.11 and independent of LiH surface temperature, suggesting a negligible activation energy for the reaction in agreement with quantum chemical calculations. The value gradually reduced, however, to 0.007 as the surface concentration of oxygen containing product approached full coverage. As the film grew beyond a monolayer, the phase lag of hydrogen product increased from 0 deg. C to 20 deg. C and the reaction probability reduced further until it approached our detection limit (∼10 -4 ). This phase lag was attributed to a diffusion-limited process in this regime. For micrometer thick hydroxide films grown in high moisture concentration environment on LiD and LiH, the reaction probability reduced to ∼4x10 -7 and was independent of exposure time. In this regime of thick hydroxide films (LiOH and/or LiOD), microcracks generated in the films to release stress provided easier pathways for moisture to reach the interface. A modified microscope, capable of both atomic force microscopy and nanoindentation, was also employed to investigate the surface morphology of hydroxide monohydrate (LiOH · H 2 O and/or LiOD · H 2 O) grown on hydroxide at high water vapor partial pressures and the kinetics of this growth

Mechanochemical Association Reaction of Interfacial Molecules Driven by Shear.

Science.gov (United States)

Khajeh, Arash; He, Xin; Yeon, Jejoon; Kim, Seong H; Martini, Ashlie

2018-05-29

Shear-driven chemical reaction mechanisms are poorly understood because the relevant reactions are often hidden between two solid surfaces moving in relative motion. Here, this phenomenon is explored by characterizing shear-induced polymerization reactions that occur during vapor phase lubrication of α-pinene between sliding hydroxylated and dehydroxylated silica surfaces, complemented by reactive molecular dynamics simulations. The results suggest that oxidative chemisorption of the α-pinene molecules at reactive surface sites, which transfers oxygen atoms from the surface to the adsorbate molecule, is the critical activation step. Such activation takes place more readily on the dehydroxylated surface. During this activation, the most strained part of the α-pinene molecules undergoes a partial distortion from its equilibrium geometry, which appears to be related to the critical activation volume for mechanical activation. Once α-pinene molecules are activated, association reactions occur between the newly attached oxygen and one of the carbon atoms in another molecule, forming ether bonds. These findings have general implications for mechanochemistry because they reveal that shear-driven reactions may occur through reaction pathways very different from their thermally induced counterparts and specifically the critical role of molecular distortion in such reactions.

Uranium oxidation: characterization of oxides formed by reaction with water

International Nuclear Information System (INIS)

Fuller, E.L. Jr.; Smyrl, N.R.; Condon, J.B.; Eager, M.H.

1983-01-01

Three different uranium oxide samples have been characterized with respect to the different preparation techniques. Results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. 27 figures

SiC Conversion Coating Prepared from Silica-Graphite Reaction

Directory of Open Access Journals (Sweden)

Back-Sub Sung

2017-01-01

Full Text Available The β-SiC conversion coatings were successfully synthesized by the SiO(v-graphite(s reaction between silica powder and graphite specimen. This paper is to describe the effects on the characteristics of the SiC conversion coatings, fabricated according to two different reaction conditions. FE-SEM, FE-TEM microstructural morphologies, XRD patterns, pore size distribution, and oxidation behavior of the SiC-coated graphite were investigated. In the XRD pattern and SAD pattern, the coating layers showed cubic SiC peak as well as hexagonal SiC peak. The SiC coatings showed somewhat different characteristics with the reaction conditions according to the position arrangement of the graphite samples. The SiC coating on graphite, prepared in reaction zone (2, shows higher intensity of beta-SiC main peak (111 in XRD pattern as well as rather lower porosity and smaller main pore size peak under 1 μm.

Migration Imaging of the Java Subduction Zones

Science.gov (United States)

Dokht, Ramin M. H.; Gu, Yu Jeffrey; Sacchi, Mauricio D.

2018-02-01

Imaging of tectonically complex regions can greatly benefit from dense network data and resolution enhancement techniques. Conventional methods in the analysis of SS precursors stack the waveforms to obtain an average discontinuity depth, but smearing due to large Fresnel zones can degrade the fine-scale topography on the discontinuity. To provide a partial solution, we introduce a depth migration algorithm based on the common scattering point method while considering nonspecular diffractions from mantle transition zone discontinuities. Our analysis indicates that, beneath the Sunda arc, the depth of the 410 km discontinuity (the 410) is elevated by 30 km and the 660 km discontinuity (the 660) is depressed by 20-40 km; the region of the strongest anticorrelation is correlated with the morphology of the subducting Indo-Australian slab. In eastern Java, a "flat" 410 coincides with a documented slab gap, showing length scales greater than 400 km laterally and 200 km vertically. This observation could be explained by the arrival of a buoyant oceanic plateau at the Java trench at approximately 8 Ma ago, which may have caused a temporary cessation of subduction and formed a tear in the subducting slab. Our results highlight contrasting depths of the 410 and 660 along the shallow-dipping slab below the Banda trench. The 660, however, becomes significantly uplifted beneath the Banda Sea, which is accompanied by enhanced reflection amplitudes. We interpret these observations as evidence for a subslab low-velocity zone, possibly related to the lower mantle upwelling beneath the subducting slab.

Partial oxidation of n-hexadecane through decomposition of hydrogen peroxide in supercritical water

KAUST Repository

Alshammari, Y.M.

2015-01-01

© 2014 The Institution of Chemical Engineers. This work reports the experimental analysis of partial oxidation of n-hexadecane under supercritical water conditions. A novel reactor flow system was developed which allows for total decomposition of hydrogen peroxide in a separate reactor followed partial oxidation of n-hexadecane in a gasification reactor instead of having both reactions in one reactor. The kinetics of hydrothermal decomposition of hydrogen peroxide was studied in order to confirm its full conversion into water and oxygen under the desired partial oxidation conditions, and the kinetic data were found in a good agreement with previously reported literature. The gas yield and gasification efficiency were investigated under different operating parameters. Furthermore, the profile of C-C/C=C ratio was studied which showed the favourable conditions for maximising yields of n-alkanes via hydrogenation of their corresponding 1-alkenes. Enhanced hydrogenation of 1-alkenes was observed at higher O/C ratios and higher residence times, shown by the increase in the C-C/C=C ratio to more than unity, while increasing the temperature has shown much less effect on the C-C/C=C ratio at the current experimental conditions. In addition, GC-MS analysis of liquid samples revealed the formation of heavy oxygenated compounds which may suggest a new addition reaction to account for their formation under the current experimental conditions. Results show new promising routes for hydrogen production with in situ hydrogenation of heavy hydrocarbons in a supercritical water reactor.

Reaction-induced fracturing during olivine serpentinization: A mechanistic investigation at the interface scale

NARCIS (Netherlands)

Plümper, O.; Røyne, A.; Malthe-Sørenssen, A.; King, H. E.; Jamtveit, B.

Serpentinization of the Earth's impermeable upper mantle is one of the most fundamental metamorphic hydration reactions. It governs lithospheric weakening, geochemical subduction zone input and possibly even the formation of life-essential building blocks. Serpentinization relies on fluid pathway

Fuel conditioning facility zone-to-zone transfer administrative controls

International Nuclear Information System (INIS)

Pope, C. L.

2000-01-01

The administrative controls associated with transferring containers from one criticality hazard control zone to another in the Argonne National Laboratory (ANL) Fuel Conditioning Facility (FCF) are described. FCF, located at the ANL-West site near Idaho Falls, Idaho, is used to remotely process spent sodium bonded metallic fuel for disposition. The process involves nearly forty widely varying material forms and types, over fifty specific use container types, and over thirty distinct zones where work activities occur. During 1999, over five thousand transfers from one zone to another were conducted. Limits are placed on mass, material form and type, and container types for each zone. Ml material and containers are tracked using the Mass Tracking System (MTG). The MTG uses an Oracle database and numerous applications to manage the database. The database stores information specific to the process, including material composition and mass, container identification number and mass, transfer history, and the operators involved in each transfer. The process is controlled using written procedures which specify the zone, containers, and material involved in a task. Transferring a container from one zone to another is called a zone-to-zone transfer (ZZT). ZZTs consist of four distinct phases, select, request, identify, and completion

Synthesis and Properties of Some polyurethane/ Partially Aromatic Polyester Casting Samples

International Nuclear Information System (INIS)

Sadek, E.M.; Mazroua, A.M.; Emam, A.S.; Motawie, A.M.

2005-01-01

A series of partially aromatic terephthalate polyesters were synthesized by melt transesterification of dimethyl terephthalate with various types of aliphatic diol compounds in 1:1.1 molar ratio. Ethylene-, di-, tri-, tetra ethylene glycol and polyethylene glycol with different molecular weights 1000, 4000, 6000 as well as the prepared dihydroxy natural rubber were used. Another series of partially aromatic adipate and sebacate polyesters based on the prepared bisphenol A and its tetrabromo derivative were also synthesized by direct polycondensation esterification with adipic and sebacic acid. Polyurethane with NCO/OH ratio equal 4 was prepared from the reaction of 2,4 toluene diisocyanate with polyethylene glycol 1000. The prepared polyurethane was mixed with different weight percentages (2, 4, 6, 8, 10 or 12 % w/w) of the prepared partially aromatic polyesters to give polyurethane/polyester compositions. Mechanical and electrical properties as well as water and chemical resistance of the prepared film samples with thickness 3-4 mm were determined and compared with those of polyurethane film sample without polyester. The data indicate that 10 % w/w of the added partially aromatic polyester increases polyurethane tensile strength, improves its insulation properties and hydrolytic stability as well as its chemical resistance. Film samples based on bisphenol A impart excellent properties as compared with those based on aliphatic glycol species and dihydroxy natural rubber. Keywords: Partially aromatic polyesters, Dimethyl terephthalate, Glycols, Bisphenol A, Tetrabromo bisphenol A, Natural rubber, Adipic acid, Sebacic acid, Polyurethane, Casting

Forward pion-nucleon charge exchange reaction and Regge constraints

International Nuclear Information System (INIS)

Huang Fei; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meibner, U.-G.

2009-01-01

We present our recent study of pion-nucleon charge exchange amplitudes above 2 GeV. We analyze the forward pion-nucleon charge exchange reaction data in a Regge model and compare the resulting amplitudes with those from the Karlsruhe-Helsinki and George-Washington-University partial-wave analyses. We explore possible high-energy constraints for theoretical baryon resonance analyses in the energy region above 2 GeV. Our results show that for the pion-nucleon charge exchange reaction, the appropriate energy region for matching meson-nucleon dynamics to diffractive scattering should be around 3 GeV for the helicity flip amplitude. (authors)

A study on the reaction between SiC and Pd, (2)

International Nuclear Information System (INIS)

Namba, Takashi; Minato, Kazuo; Yamawaki, Michio; Fukuda, Kousaku.

1989-01-01

An out of pile experiment was performed on the corrosion of the SiC layer by fission product Pd in the Triso-coated fuel particles of high temperature gas-cooled reactor. In order to clarify the corrosion mechanism, influence of Pd activity on the corrosion was studied. Seven Au-Pd alloys with different Pd contents were prepared and simulated TRISO-coated particles were heated in the powder of the alloys at 1473 and 1573K. The Pd-SiC reaction zones were observed and analyzed by XMA. From the experimental results, the reaction rate was found to be dependent on Pd activity. The dependence of the reaction rate on temperature and time was also discussed. (author)

Molecular differences in transition zone and peripheral zone prostate tumors

Science.gov (United States)

Sinnott, Jennifer A.; Rider, Jennifer R.; Carlsson, Jessica; Gerke, Travis; Tyekucheva, Svitlana; Penney, Kathryn L.; Sesso, Howard D.; Loda, Massimo; Fall, Katja; Stampfer, Meir J.; Mucci, Lorelei A.; Pawitan, Yudi; Andersson, Sven-Olof; Andrén, Ove

2015-01-01

Prostate tumors arise primarily in the peripheral zone (PZ) of the prostate, but 20–30% arise in the transition zone (TZ). Zone of origin may have prognostic value or reflect distinct molecular subtypes; however, it can be difficult to determine in practice. Using whole-genome gene expression, we built a signature of zone using normal tissue from five individuals and found that it successfully classified nine tumors of known zone. Hypothesizing that this signature captures tumor zone of origin, we assessed its relationship with clinical factors among 369 tumors of unknown zone from radical prostatectomies (RPs) and found that tumors that molecularly resembled TZ tumors showed lower mortality (P = 0.09) that was explained by lower Gleason scores (P = 0.009). We further applied the signature to an earlier study of 88 RP and 333 transurethral resection of the prostate (TURP) tumor samples, also of unknown zone, with gene expression on ~6000 genes. We had observed previously substantial expression differences between RP and TURP specimens, and hypothesized that this might be because RPs capture primarily PZ tumors, whereas TURPs capture more TZ tumors. Our signature distinguished these two groups, with an area under the receiver operating characteristic curve of 87% (P zones. Zone of origin may be important to consider in prostate tumor biomarker research. PMID:25870172

Space Weather Influence on the Earth Climate: Possible Manifestations in Wheat Markets Reaction

Science.gov (United States)

Pustilnik, Lev; Yom Din, Gregory; Zagnetko, Alexander

We consider problem of a possible influence of unfavorable states of the space weather on agri-culture market through chain of connections: "space weather"-"earth weather"-"agriculture crops"-"price reaction". We show that new manifestations of "space weather"-"earth weather" relations discovered in the last time allow to revise wide field of expected solar-terrestrial con-nections. In the previous works we proposed possible mechanisms of wheat market reaction in the form of price bursts on the specific unfavorable states of space weather. We show that implementation of considered "price reaction scenarios" is possible only for condition of simul-taneous realization of several necessary conditions: high sensitivity of local earth weather in selected region to space weather; state of "high risk agriculture" in selected agriculture zone; high sensitivity of agricultural market to possible deficit of supply. Results of previous works included application of this approach to wheat market in Medieval England and to modern USA durum market showed that real connection between wheat price bursts and space weather state is observed with high confidence level. The aim of present work is answer on the ques-tion, why wheat markets in one region are sensitive to space weather factor, while another regional wheat markets demonstrate absolute indifferent reaction on this factor. For this aim we consider distribution of sensitivity of wheat markets in Europe to space weather as function of localization in different climatic zones. We analyze giant database of 95 European wheat markets from 14 countries during about 600-year period (1260-1912). We show that observed sensitivity of wheat market to space weather effects controlled, first of all, by type of predomi-nant climate in different zones of agriculture. Wheat markets in the North and part of Central Europe (England, Iceland, Holland) shows reliable sensitivity to space weather in minimum states of solar activity with low

Adverse reaction after hyaluronan injection for minimally invasive papilla volume augmentation

DEFF Research Database (Denmark)

Bertl, Kristina; Gotfredsen, Klaus; Jensen, Simon S

2017-01-01

or mucosal necrosis or any permanent damage. CONCLUSION: Most likely, water attraction over time by the highly hygroscopic HY, exerted progressively an external vascular compression and at least partial occlusion of neighbouring blood vessels. An infection or an allergic reaction seems unlikely, since all...

Partial wave analysis of KKPI system in D and E/IOTA region

International Nuclear Information System (INIS)

Chung, S.U.; Fernow, R.; Kirk, H.

1985-01-01

A partial wave analysis and a Dalitz plot analysis of high-statistics data from reaction π - p → K + K/sub S/π - n at 8.0 GeV/c show that the D(1285) is a J/sup PG/ = 1 ++ state and the E(1420) a J/sup PG/ = 0 -+ state both with a substantial deltaπ decay mode. The 1 ++ K*anti K wave exhibits a rapid rise near threshold but no evidence of a resonance in the E region. The assignment of J/sup PG/ = O -+ to the E is confirmed from a Dalitz-plot analysis of the reaction pp → K + K/sub S/π - X 0 . 11 refs., 5 figs

On the time behaviour of the concentration of pyrazinium radical cations in the early stage of the Maillard reaction

Science.gov (United States)

Stoesser, Reinhard; Klein, Jeannette; Peschke, Simone; Zehl, Andrea; Cämmerer, Bettina; Kroh, Lothar W.

2007-08-01

During the early stage of the Maillard reaction pyrazinium radical cations were detected by ESR within the reaction system D-glucose/glycine. The spectra were characterized by completely resolved hyperfine structure. The partial pressure of oxygen and the radical concentrations were measured directly in the reaction mixture by ESR using solutions of the spin probe TEMPOL and of DPPH, respectively. There are quantitative and qualitative relations of the actual concentration of the radical ions to the partial pressure of oxygen, the temperature-time regime and the mechanical mixing of the reaction system. These macroscopic parameters significantly affect both the induction period and the velocity of the time-dependent formation of free radicals. From in situ variations of p(O 2) and p(Ar) including the connected mixing effects caused by the passing the gases through the reaction mixture, steric and chemical effects of the stabilization of the radical ions were established. The determination of suitable and relevant conditions for stabilization and subsequent radical reactions contributes to the elucidation of the macroscopically known antioxidant activity of Maillard products.

Low-Q structure related to partially saturated pores within the reservoir beneath The Geysers area in the northern California

Science.gov (United States)

Matsubara, M.

2011-12-01

with a high-Q zone. A vertical cross section shows the low-Q zone is consistent with the reservoir as it extends through the main greywacke and into the uppermost part of the felsite. Most of the felsite has high-Q, however, the portion of the reservoir that extends into the felsite has low-Q. The Geysers geothermal area is bounded by Collayomi fault zone to the northeast and the Mercuryville fault zone to the southwest. The Geysers Peak fault runs from northwest to southeast about 3 km southwest of the Mercuryville fault. The Mercuryville fault dips to northeast and the Geysers Peak fault dips to southwest. High-Q zone is located between these faults and the width of this zone broadens as the depth increases corresponding to the fault geometry. The presence of liquid water introduces high-Vp/Vs, however, steam rich zones become low-Vp/Vs. Near the transition zone between the water and steam, laboratory experiments indicate that the amplitude becomes extremely small (Ito et al., 1979). A partially saturated zone has lower Q than a fully saturated zone, and a dry zone has high-Q. A low-Q zone with low-Vp/Vs corresponding to the reservoir indicates that the reservoir is partially saturated with steam and water near transition zone.

Kinetics of two simultaneous second-order reactions occurring in different zones

International Nuclear Information System (INIS)

Dole, M.; Hsu, C.S.; Patel, V.M.; Patel, G.N.

1975-01-01

Equations have been derived for the case of free radicals recombining according to the second-order kinetics with or without diffusion control under the conditions that there are two simultaneous spatially separated recombination reactions but that only the overall free-radical concentration can be observed. The properties of these equations are discussed and methods for determining the three independent parameters in the first case and five in the second developed. The resulting equations have been applied to the interpretation of data obtained in studying the decay of allyl chain free radicals in irradiated extended chain crystalline polyethylene

Partial tooth gear bearings

Science.gov (United States)

Vranish, John M. (Inventor)

2010-01-01

A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

Meridional flow in the solar convection zone. I. Measurements from gong data

Energy Technology Data Exchange (ETDEWEB)

Kholikov, S. [National Solar Observatories, Tucson, AZ 85719 (United States); Serebryanskiy, A. [Ulugh Beg Astronomical Institute, Uzbek Academy of Science, Tashkent 100052 (Uzbekistan); Jackiewicz, J., E-mail: kholikov@noao.edu [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)

2014-04-01

Large-scale plasma flows in the Sun's convection zone likely play a major role in solar dynamics on decadal timescales. In particular, quantifying meridional motions is a critical ingredient for understanding the solar cycle and the transport of magnetic flux. Because the signal of such features can be quite small in deep solar layers and be buried in systematics or noise, the true meridional velocity profile has remained elusive. We perform time-distance helioseismology measurements on several years worth of Global Oscillation Network Group Doppler data. A spherical harmonic decomposition technique is applied to a subset of acoustic modes to measure travel-time differences to try to obtain signatures of meridional flows throughout the solar convection zone. Center-to-limb systematics are taken into account in an intuitive yet ad hoc manner. Travel-time differences near the surface that are consistent with a poleward flow in each hemisphere and are similar to previous work are measured. Additionally, measurements in deep layers near the base of the convection zone suggest a possible equatorward flow, as well as partial evidence of a sign change in the travel-time differences at mid-convection zone depths. This analysis on an independent data set using different measurement techniques strengthens recent conclusions that the convection zone may have multiple 'cells' of meridional flow. The results may challenge the common understanding of one large conveyor belt operating in the solar convection zone. Further work with helioseismic inversions and a careful study of systematic effects are needed before firm conclusions of these large-scale flow structures can be made.

Increasing Weldability of Service-Aged Reformer Tubes by Partial Solution Annealing

Science.gov (United States)

Mostafaei, M.; Shamanian, M.; Purmohamad, H.; Amini, M.

2016-04-01

A dissimilar joint of 25Cr-35Ni/30Cr-48Ni (HP/HV) heat-resistant steels was evaluated. The investigations indicated that the as-cast HP alloy contained M7C3, M23C6, and NbC carbides and HV alloy with 5 wt.% tungsten, contained M23C6 and M6C carbides embedded in an austenitic matrix. After 8 years of ex-service aging at 1050 °C, the ductility of HP/HV reformer tubes was decreased dramatically, and thus, the repair welding of the aged HP/HV dissimilar joint was at a risk. In order to repair the aged reformer tubes and increase weldability properties, a new partial solution annealing treatment was designed. Mechanical testing results showed that partial solution annealing at 1200 °C for 6 h increased the elongation and toughness of the aged HP and HV alloys drastically. Also, a mechanism for constitutional liquation cracking in the heat-affected zones (HAZ) of the HP/HV dissimilar joint was proposed. In the HAZ of the aged HP/HV welded joint, the cracks around the locally melted carbides were initiated and propagated during carbides solidification at the cooling cycle of welding associated with the decrease in the ductility of the aged HP and HV alloys. In addition, Varestraint weldability test showed that the susceptibility to hot cracking was decreased with partial solution annealing.

Reaction of nickel with uranium mononitride; Reaction du nickel avec le nitrure d'uranium

Energy Technology Data Exchange (ETDEWEB)

Anselin, F; Calais, D; Lorenzelli, N; Passefort, J C [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1965-07-01

UN-Ni system has been investigated in solid phase by diffusion couples UN-Ni or by mixed powders pressed and sintered. Studies have been carried out by micrography, X-rays and microanalysis with a CASTAING microprobe. UN-Ni compatibility is quite good up to 600 C; beyond this temperature diffusion zones corresponding to UNi{sub 5} and U{sub 2}N{sub 3} appear in the couples either reaction : 3 U N + 5 Ni {yields} U{sub 2}N{sub 3} + UNi{sub 5}; UN + 5 Ni {yields} UNi{sub 5}+ 1/2 N{sub 2} takes place from 700 C according to nitrogen pressure involved. For temperatures between 800 and 1000 C nickel solubility in uranium nitride is 1500 {+-} 500 wt ppm. (authors) [French] Le systeme UN-Ni a ete etudie par diffusion en phase solide a partir de couples (UN-Ni) ou de melanges pulverulents presses et frittes. Les techniques utilisees sont la micrographie, les rayons X et l'analyse ponctuelle a la microsonde de CASTAING. La compatibilite UN-Ni est bonne jusqu'a 600 C; au-dela il apparait dans les couples de diffusion des zones correspondant a UNi{sub 5} et U{sub 2}N{sub 3}. L'une ou l'autre des deux reactions: 3UN + 5 Ni {yields} U{sub 2}N{sub 3} + UNi{sub 5}; UN + 5 Ni {yields} UNi{sub 5} + 1/2 N{sub 2} se produisant des 700 C suivant la pression d'azote exercee. La solubilite du nickel dans le nitrure d'uranium pour des temperatures comprises entre 800 et 1000 C est de 1500 {+-} 500 ppm en poids. (auteurs)

Selection of anthracnose resistant common beans using detached leaves in partially controlled environment

Directory of Open Access Journals (Sweden)

Alisson Campos Pereira

2014-08-01

Full Text Available The objectives of this study were to evaluate the possibility of selecting anthracnose resistant common bean plants using detached primary leaves in partially controlled environment of a greenhouse and identify differences in the reaction of genotypes to anthracnose. The common bean cultivars Ouro Negro, OuroVermelho, ManteigãoFosco 11, Rudá, Rudá-R, VP8, BRSMG Madrepérola, Pérola, MeiaNoite and BRSMG Talismãwere characterizedfor resistance to the races 65, 81 and 453 of Colletotrichum lindemuthianum and the method of detached primary leaves was compared to the method with the traditional inoculation of plants at the phenological stage V2. The lines Rudá, Rudá-R and Pérola were inoculated with the races 65 and 453 of C. lindemuthianum, aiming to assess the rate of coincidence of anthracnose severity by both inoculation methods. In general, the two methods presented similar results for the reaction of the cultivars. The use of detached primary leaves of common bean plants in the partially controlled environment was feasible for selection of plants resistant to anthracnose and has the advantages of low-needed infrastructure and reduction of resources, space and time.

New results on the Roper resonance and the P{sub 11} partial wave

Energy Technology Data Exchange (ETDEWEB)

Sarantsev, A.V. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Fuchs, M. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); Kotulla, M. [Physikalisches Institut, Universitaet Basel (Switzerland); II. Physikalisches Institut, Universitaet Giessen (Germany); Thoma, U. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); II. Physikalisches Institut, Universitaet Giessen (Germany); Ahrens, J. [Institut fuer Kernphysik, Universitaet Mainz (Germany); Annand, J.R.M. [Department of Physics and Astronomy, University of Glasgow (United Kingdom); Anisovich, A.V. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Anton, G. [Physikalisches Institut, Universitaet Erlangen (Germany); Bantes, R. [Physikalisches Institut, Universitaet Bonn (Germany); Bartholomy, O. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); Beck, R. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); Institut fuer Kernphysik, Universitaet Mainz (Germany); Beloglazov, Yu. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Castelijns, R. [KVI, Groningen (Netherlands); Crede, V. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); Department of Physics, Florida State University (United States); Ehmanns, A.; Ernst, J.; Fabry, I. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany); Flemming, H. [Physikalisches Institut, Universitaet Bochum (Germany); Foesel, A. [Physikalisches Institut, Universitaet Erlangen (Germany); Funke, Chr. [Helmholtz-Institut fuer Strahlen- und Kernphysik der Universitaet Bonn (Germany)] (and others)

2008-01-17

Properties of the Roper resonance, the first scalar excitation of the nucleon, are determined. Pole positions and residues of the P{sub 11} partial wave are studied in a combined analysis of pion- and photo-induced reactions. We find the Roper pole at {l_brace}(1371{+-}7)-i(92{+-}10){r_brace} MeV and an elasticity of 0.61{+-}0.03. The largest decay coupling is found for the N{sigma} ({sigma}=({pi}{pi})-S-wave). The analysis is based on new data on {gamma}p{yields}p{pi}{sup 0}{pi}{sup 0} for photons in the energy range from the two-pion threshold to 820 MeV from TAPS at Mainz and from 0.4 to 1.3 GeV from Crystal Barrel at Bonn and includes further data from other experiments. The partial wave analysis excludes the possibility that the Roper resonance is split into two states with different partial decay widths.

Biomass hydrolysis inhibition at high hydrogen partial pressure in solid-state anaerobic digestion.

Science.gov (United States)

Cazier, E A; Trably, E; Steyer, J P; Escudie, R

2015-08-01

In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

SOCON: a computer model for analyzing the behavior of sodium-concrete reactions

International Nuclear Information System (INIS)

Nguyen, D.G.; Muhlestein, L.D.

1985-03-01

Guided by experimental evidence available to date, ranging from basic laboratory studies to large scale tests, a mechanistic computer model (the SOCON model) has been developed to analyze the behavior of SOdium-CONcrete reactions. The model accounts for the thermal, chemical and mechanical phenomena which interact to determine the consequences of the reactions. Reaction limiting mechanisms could be any process which reduces water release and sodium transport to fresh concrete; the buildup of the inert reaction product layer would increase the resistance to sodium transport; water dry-out would decrease the bubble agitation transport mechanism. However, stress-induced failure of concrete, such as spalling, crushing and cracking, and a massive release of gaseous products (hydrogen, water vapor and CO 2 ) would increase the transport of sodium to the reaction zone. The results of SOCON calculations are in excellent agreement with measurements obtained from large-scale sodium-limestone concrete reaction tests of duration up to 100 hours conducted at the Hanford Engineering Development Laboratory. 8 refs., 7 figs

WorkZoneQ user guide for two-lane freeway work zones.

Science.gov (United States)

2013-06-01

WorkZoneQ was developed in Visual Basic for Applications (VBA) to implement the results of the previous study, : Queue and Users Costs in Highway Work Zones. This report contains the WorkZoneQ user guide. WorkZoneQ : consists of eight Excel ...

Reaction of ketene ions with ammonia

International Nuclear Information System (INIS)

Iraqi, M.; Lifshitz, C.; Reuben, B.G.

1991-01-01

Reactions of ketene ions with NH 3 , ND 3 , H 2 O, and CH 4 were investigated in a selected ion flow tube (SIFT). There were no observable products for H 2 O and CH 4 and no ion/neutral complex stabilization in any of the systems investigated. The ammonia system demonstrated two reaction channels, in agreement with previous FTICR data (1) distonic ion CH 2 NH 3 sm-bullet + formation, with a branching ratio of 0.2 and (2) proton transfer, with a branching ratio of 0.8. The overall second-order rate constant for NH 3 is (2.2 ± 0.15) x 10 -9 cm 3 molecule -1 s -1 , in agreement with the gas kinetic ion-dipole collision rate. Isotope scrambling was studied for primary (CH 2 CO + ) and for secondary (CH 2 NX 3 sm-bullet + and NX 4 + , X = H or D) proton-transfer reactions with ND 3 ; CH 2 NH 3 sm-bullet + appears to transfer an X + ion to ND 3 without any scrambling. CH 2 CO sm-bullet + undergoes reactions with partial scrambling and NX 4 + seems to react with almost complete scrambling. The results are compared with these of Adams, Smith, and Henchman on the NH 4 + /ND 3 system

Segregation and Microstructure in the Fusion zones of Laser joints of Al-10%Si coated Boron Steel

Energy Technology Data Exchange (ETDEWEB)

Kwon, Min-Suck [Hyundai Hysco Co., Ltd, Ulsan (Korea, Republic of); Kang, Chung-Yun [Pusan National University, Busan (Korea, Republic of)

2016-01-15

During laser welding of Al-10 wt%Si coated boron steel, which is used in the automotive industry, Al and Si, which are elements of the coated layer, are diluted in the fusion zone; then, the concentration of Al and Si is distributed randomly. The segregation can be roughly classified into two types. The first forms along the fusion boundary in a long comet shape in the depth direction of the fusion zone. The Al concentration of this comet shape is Fe3(Al, Si)and the material is composed of a single phase. This segregation phase is formed at the same time as the melting of the base metal and the diluting of the coated layer of Fe(Al, Si), without reaction of the molten metal. Then, a static dissolution reaction of the diluted coated layer occurs, scarcely stirring the molten metal; the concentration of Al and Si is reduced to 1/2. The second type of segregation is formed by martensite and bainte in the fusion zone of the segregated zone; the composition of Al is 1.28⁓0.48 wt%. Considering the results of the analysis of the Fe(Si,C, Mn,Cr)-xwt%Al quasi binary phase diagram, performed using Thermo-Calc, segregated zones are solidified in the form “L→L+α→γ”. Also, and as a result, it was found that the phase transformation from γ under-cooling results in the solid phase, which undergoes bainite transformation and is transformed to martensite.

Segregation and Microstructure in the Fusion zones of Laser joints of Al-10%Si coated Boron Steel

International Nuclear Information System (INIS)

Kwon, Min-Suck; Kang, Chung-Yun

2016-01-01

During laser welding of Al-10 wt%Si coated boron steel, which is used in the automotive industry, Al and Si, which are elements of the coated layer, are diluted in the fusion zone; then, the concentration of Al and Si is distributed randomly. The segregation can be roughly classified into two types. The first forms along the fusion boundary in a long comet shape in the depth direction of the fusion zone. The Al concentration of this comet shape is Fe3(Al, Si)and the material is composed of a single phase. This segregation phase is formed at the same time as the melting of the base metal and the diluting of the coated layer of Fe(Al, Si), without reaction of the molten metal. Then, a static dissolution reaction of the diluted coated layer occurs, scarcely stirring the molten metal; the concentration of Al and Si is reduced to 1/2. The second type of segregation is formed by martensite and bainte in the fusion zone of the segregated zone; the composition of Al is 1.28⁓0.48 wt%. Considering the results of the analysis of the Fe(Si,C, Mn,Cr)-xwt%Al quasi binary phase diagram, performed using Thermo-Calc, segregated zones are solidified in the form “L→L+α→γ”. Also, and as a result, it was found that the phase transformation from γ under-cooling results in the solid phase, which undergoes bainite transformation and is transformed to martensite.

Recent Advances in Hyporheic Zone Science

Science.gov (United States)

Hester, E. T.

2017-12-01

The hyporheic zone exists beneath and adjacent to streams and rivers where surface water and groundwater interact. It provides unique habitat for aquatic organisms, can buffer surface water temperatures, and can be highly reactive, processing nutrients and improving water quality. The hyporheic zone is the subject of considerable research and the past year in WRR witnessed important conceptual advances. A key focus was rigorous evaluation of mixing between surface water and groundwater that occurs within hyporheic sediments. Field observations indicate that greater mixing occurs in the hyporheic zone than in deeper groundwater, and this distinction has been explored by recent numerical modeling studies, but more research is needed to fully understand the causes. A commentary this year in WRR proposed that hyporheic mixing is enhanced by a combination of fluctuating boundary conditions and multiscale physical and chemical spatial heterogeneity but confirmation is left to future research. This year also witnessed the boundaries of knowledge pushed back in a number of other key areas. Field quantification of hyporheic exchange and reactions benefited from advances including the use and interpretation of high frequency nutrient sensors, actively heater fiber optic sensors, isotope tracers, and geophysical methods such as electrical resistivity imaging. Conceptual advances were made in understanding the effects of unsteady environmental conditions (e.g., tides and storms) and preferential flow on hyporheic processes. Finally, hyporheic science is being brought increasingly to bear on applied issues such as informing nutrient removal crediting for stream restoration practices, for example in the Chesapeake Bay watershed.

ZoneLib

DEFF Research Database (Denmark)

Jessen, Jan Jacob; Schiøler, Henrik

2006-01-01

We present a dynamic model for climate in a livestock building divided into a number of zones, and a corresponding modular Simulink library (ZoneLib). While most literature in this area consider air flow as a control parameter we show how to model climate dynamics using actual control signals...... development of ZoneLib....

A new type of power energy for accelerating chemical reactions: the nature of a microwave-driving force for accelerating chemical reactions.

Science.gov (United States)

Zhou, Jicheng; Xu, Wentao; You, Zhimin; Wang, Zhe; Luo, Yushang; Gao, Lingfei; Yin, Cheng; Peng, Renjie; Lan, Lixin

2016-04-27

The use of microwave (MW) irradiation to increase the rate of chemical reactions has attracted much attention recently in nearly all fields of chemistry due to substantial enhancements in reaction rates. However, the intrinsic nature of the effects of MW irradiation on chemical reactions remains unclear. Herein, the highly effective conversion of NO and decomposition of H2S via MW catalysis were investigated. The temperature was decreased by several hundred degrees centigrade. Moreover, the apparent activation energy (Ea') decreased substantially under MW irradiation. Importantly, for the first time, a model of the interactions between microwave electromagnetic waves and molecules is proposed to elucidate the intrinsic reason for the reduction in the Ea' under MW irradiation, and a formula for the quantitative estimation of the decrease in the Ea' was determined. MW irradiation energy was partially transformed to reduce the Ea', and MW irradiation is a new type of power energy for speeding up chemical reactions. The effect of MW irradiation on chemical reactions was determined. Our findings challenge both the classical view of MW irradiation as only a heating method and the controversial MW non-thermal effect and open a promising avenue for the development of novel MW catalytic reaction technology.

An optimized chemical kinetic mechanism for HCCI combustion of PRFs using multi-zone model and genetic algorithm

International Nuclear Information System (INIS)

Neshat, Elaheh; Saray, Rahim Khoshbakhti

2015-01-01

Highlights: • A new chemical kinetic mechanism for PRFs HCCI combustion is developed. • New mechanism optimization is performed using genetic algorithm and multi-zone model. • Engine-related combustion and performance parameters are predicted accurately. • Engine unburned HC and CO emissions are predicted by the model properly. - Abstract: Development of comprehensive chemical kinetic mechanisms is required for HCCI combustion and emissions prediction to be used in engine development. The main purpose of this study is development of a new chemical kinetic mechanism for primary reference fuels (PRFs) HCCI combustion, which can be applied to combustion models to predict in-cylinder pressure and exhaust CO and UHC emissions, accurately. Hence, a multi-zone model is developed for HCCI engine simulation. Two semi-detailed chemical kinetic mechanisms those are suitable for premixed combustion are used for n-heptane and iso-octane HCCI combustion simulation. The iso-octane mechanism contains 84 species and 484 reactions and the n-heptane mechanism contains 57 species and 296 reactions. A simple interaction between iso-octane and n-heptane is considered in new mechanism. The multi-zone model is validated using experimental data for pure n-heptane and iso-octane. A new mechanism is prepared by combination of these two mechanisms for n-heptane and iso-octane blended fuel, which includes 101 species and 594 reactions. New mechanism optimization is performed using genetic algorithm and multi-zone model. Mechanism contains low temperature heat release region, which decreases with increasing octane number. The results showed that the optimized chemical kinetic mechanism is capable of predicting engine-related combustion and performance parameters. Also after implementing the optimized mechanism, engine unburned HC and CO emissions predicted by the model are in good agreement with the corresponding experimental data

Mechanistic insights into the dehalogenation reaction of fluoroacetate/fluoroacetic acid

International Nuclear Information System (INIS)

Miranda-Rojas, Sebastián; Toro-Labbé, Alejandro

2015-01-01

Fluoroacetate is a toxic compound whose environmental accumulation may represent an important contamination problem, its elimination is therefore a challenging issue. Fluoroacetate dehalogenase catalyzes its degradation through a two step process initiated by an S N 2 reaction in which the aspartate residue performs a nucleophilic attack on the carbon bonded to the fluorine; the second step is hydrolysis that releases the product as glycolate. In this paper, we present a study based on density functional theory calculations of the S N 2 initiation reaction modeled through the interaction between the substrate and the propionate anion as the nucleophile. Results are analyzed within the framework of the reaction force and using the reaction electronic flux to identify and characterize the electronic activity that drives the reaction. Our results reveal that the selective protonation of the substrate catalyzes the reaction by decreasing the resistance of the structural and electronic reorganization needed to reach the transition state. Finally, the reaction energy is modulated by the degree of stabilization of the fluoride anion formed after the S N 2 reaction. In this way, a site-induced partial protonation acts as a chemical switch in a key process that determines the output of the reaction

Mechanistic insights into the dehalogenation reaction of fluoroacetate/fluoroacetic acid

Energy Technology Data Exchange (ETDEWEB)

Miranda-Rojas, Sebastián, E-mail: sebastian.miranda@unab.cl [Chemical Processes and Catalysis (CPC), Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Avenida República 275, Santiago (Chile); Toro-Labbé, Alejandro [Laboratorio de Química Teórica Computacional (QTC), Facultad de Química, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, Santiago (Chile)

2015-05-21

Fluoroacetate is a toxic compound whose environmental accumulation may represent an important contamination problem, its elimination is therefore a challenging issue. Fluoroacetate dehalogenase catalyzes its degradation through a two step process initiated by an S{sub N}2 reaction in which the aspartate residue performs a nucleophilic attack on the carbon bonded to the fluorine; the second step is hydrolysis that releases the product as glycolate. In this paper, we present a study based on density functional theory calculations of the S{sub N}2 initiation reaction modeled through the interaction between the substrate and the propionate anion as the nucleophile. Results are analyzed within the framework of the reaction force and using the reaction electronic flux to identify and characterize the electronic activity that drives the reaction. Our results reveal that the selective protonation of the substrate catalyzes the reaction by decreasing the resistance of the structural and electronic reorganization needed to reach the transition state. Finally, the reaction energy is modulated by the degree of stabilization of the fluoride anion formed after the S{sub N}2 reaction. In this way, a site-induced partial protonation acts as a chemical switch in a key process that determines the output of the reaction.

Stabilization and structure of N-heptane flame on CWJ-spray burner with kHZ SPIV and OH-PLIF

KAUST Repository

Mansour, Morkous S.

2015-08-31

A curved wall-jet (CWJ) burner was employed to stabilize turbulent spray flames that utilized a Coanda effect by supplying air as annular-inward jet over a curved surface, surrounding an axisymmetric solid cone fuel spray. The stabilization characteristics and structure of n-heptane/air turbulent flames were investigated with varying fuel and air flow rates and the position of pressure atomizer (L). High-speed planar laser-induced fluorescence (PLIF) of OH radicals delineated reaction zone contours and simultaneously stereoscopic particle image velocimetry (SPIV) quantified the flow field features, involving turbulent mixing within spray, ambient air entrainment and flame-turbulence interaction. High turbulent rms velocities were generated within the recirculation zone, which improved the flame stabilization. OH fluorescence signals revealed a double flame structure near the stabilization edge of lifted flame that consisted of inner partially premixed flame and outer diffusion flame front. The inner reaction zone is highly wrinkled and folded due to significant turbulent mixing between the annular-air jet and the fuel vapor generated from droplets along the contact interface of this air jet with the fuel spray. Larger droplets, having higher momentum are able to penetrate the inner reaction zone and then vaporized in the low-speed hot region bounded by these reaction zones; this supports the outer diffusion flame. Frequent local extinctions in the inner reaction zone were observed at low air flow rate. As flow rate increases, the inner zone is more resistant to local extinction despite of its high wrinkling and corrugation degree. However, the outer reaction zone exhibits stable and mildly wrinkled features irrespective of air flow rate. The liftoff height increases with the air mass flow rate but decreases with L.

MRI-negative refractory partial epilepsy: role for diffusion tensor imaging in high field MRI.

Science.gov (United States)

Chen, Qin; Lui, Su; Li, Chun-Xiao; Jiang, Li-Jun; Ou-Yang, Luo; Tang, He-Han; Shang, Hui-Fang; Huang, Xiao-Qi; Gong, Qi-Yong; Zhou, Dong

2008-07-01

Our aim is to use the high field MR scanner (3T) to verify whether diffusion tensor imaging (DTI) could help in locating the epileptogenic zone in patients with MRI-negative refractory partial epilepsy. Fifteen patients with refractory partial epilepsy who had normal conventional MRI, and 40 healthy volunteers were recruited for the study. DTI was performed on a 3T MR scanner, individual maps of mean diffusivity (MD) and fractional anisotropy (FA) were calculated, and Voxel-Based Analysis (VBA) was performed for individual comparison between patients and controls. Voxel-based analysis revealed significant MD increase in variant regions in 13 patients. The electroclinical seizure localization was concurred to seven patients. No patient exhibited regions of significant decreased MD. Regions of significant reduced FA were observed in five patients, with two of these concurring with electroclinical seizure localization. Two patients had regions of significant increase in FA, which were distinct from electroclinical seizure localization. Our study's results revealed that DTI is a responsive neuroradiologic technique that provides information about the epileptogenic areas in patients with MRI-negative refractory partial epilepsy. This technique may also helpful in pre-surgical evaluation.

Radiation zoning for vacuum equipment of the CERN Large Hadron Collider

CERN Document Server

Mahner, E; Cruikshank, P; Forkel-Wirth, D; Jiménez, J M

2010-01-01

Beam losses in high-energy particle accelerators are responsible for beam lifetime degradation. In the LHC beam losses will create a shower of particles while interacting with materials from the beam pipes and surroundings, resulting in a partial activation of material in the tunnel. Efforts have been made during the accelerator design to monitor and to reduce the activation induced by beam losses. Traceability for all vacuum components has been established providing a tool to follow-up individually each component or subcomponents installed in the tunnel, regardless of their future destination e.g. recycling or disposal. In the latter case, the history of vacuum components will allow calculating the beam-induced activation and permit comparisons with in-situ and ex-situ measurements. This zoning will also help to reduce collective and individual radiation doses to personnel during interventions. The paper presents the vacuum system layout and describes the LHC vacuum zoning and its implementation using an ORA...

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multizone Reaction Kinetics: Modeling of Decarburization

Science.gov (United States)

Rout, Bapin Kumar; Brooks, Geoffrey; Akbar Rhamdhani, M.; Li, Zushu; Schrama, Frank N. H.; Overbosch, Aart

2018-03-01

In a previous study by the authors (Rout et al. in Metall Mater Trans B 49:537-557, 2018), a dynamic model for the BOF, employing the concept of multizone kinetics was developed. In the current study, the kinetics of decarburization reaction is investigated. The jet impact and slag-metal emulsion zones were identified to be primary zones for carbon oxidation. The dynamic parameters in the rate equation of decarburization such as residence time of metal drops in the emulsion, interfacial area evolution, initial size, and the effects of surface-active oxides have been included in the kinetic rate equation of the metal droplet. A modified mass-transfer coefficient based on the ideal Langmuir adsorption equilibrium has been proposed to take into account the surface blockage effects of SiO2 and P2O5 in slag on the decarburization kinetics of a metal droplet in the emulsion. Further, a size distribution function has been included in the rate equation to evaluate the effect of droplet size on reaction kinetics. The mathematical simulation indicates that decarburization of the droplet in the emulsion is a strong function of the initial size and residence time. A modified droplet generation rate proposed previously by the authors has been used to estimate the total decarburization rate by slag-metal emulsion. The model's prediction shows that about 76 pct of total carbon is removed by reactions in the emulsion, and the remaining is removed by reactions at the jet impact zone. The predicted bath carbon by the model has been found to be in good agreement with the industrially measured data.

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multizone Reaction Kinetics: Modeling of Decarburization

Science.gov (United States)

Rout, Bapin Kumar; Brooks, Geoffrey; Akbar Rhamdhani, M.; Li, Zushu; Schrama, Frank N. H.; Overbosch, Aart

2018-06-01

In a previous study by the authors (Rout et al. in Metall Mater Trans B 49:537-557, 2018), a dynamic model for the BOF, employing the concept of multizone kinetics was developed. In the current study, the kinetics of decarburization reaction is investigated. The jet impact and slag-metal emulsion zones were identified to be primary zones for carbon oxidation. The dynamic parameters in the rate equation of decarburization such as residence time of metal drops in the emulsion, interfacial area evolution, initial size, and the effects of surface-active oxides have been included in the kinetic rate equation of the metal droplet. A modified mass-transfer coefficient based on the ideal Langmuir adsorption equilibrium has been proposed to take into account the surface blockage effects of SiO2 and P2O5 in slag on the decarburization kinetics of a metal droplet in the emulsion. Further, a size distribution function has been included in the rate equation to evaluate the effect of droplet size on reaction kinetics. The mathematical simulation indicates that decarburization of the droplet in the emulsion is a strong function of the initial size and residence time. A modified droplet generation rate proposed previously by the authors has been used to estimate the total decarburization rate by slag-metal emulsion. The model's prediction shows that about 76 pct of total carbon is removed by reactions in the emulsion, and the remaining is removed by reactions at the jet impact zone. The predicted bath carbon by the model has been found to be in good agreement with the industrially measured data.

Structural changes of noble metal catalysts during ignition and extinction of the partial oxidation of methane studied by advanced QEXAFS techniques

DEFF Research Database (Denmark)

Grunwaldt, Jan-Dierk; Beier, M.; Kimmerle, B.

2009-01-01

The dynamics of the ignition and extinction of the catalytic partial oxidation (CPO) of methane to hydrogen and carbon monoxide over Pt-Rh/Al2O3 and Pt/Al2O3 were studied in the subsecond timescale using quick-EXAFS with a novel cam-driven X-ray monochromator employing Si(111) and Si(311) crystals...... to discuss the potential and limitation of this technique in catalysis and related areas. With respect to the noble metal catalysed partial oxidation of methane, several interesting observations were made: structural changes during ignition were-independent of the chosen reaction conditions......-significantly faster than during the extinction of the reaction. The dynamic behavior of the catalysts was dependent on the flow conditions and the respective noble metal component(s). Higher reaction gas flow led to a faster ignition process. While the ignition over Pt-Rh/Al2O3 occurred at lower temperature than over...

Empowerment Zones and Enterprise Districts - MDC_EnterpriseZone

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Polygon feature class of Miami Dade County Enterprise Zones. Enterprise Zones are special areas in the county where certain incentives from the State are available...

Serpentinization of abyssal peridotites from the MARK area, Mid-Atlantic Ridge: Sulfur geochemistry and reaction modeling

Science.gov (United States)

Alt, J.C.; Shanks, Wayne C.

2003-01-01

The opaque mineralogy and the contents and isotope compositions of sulfur in serpentinized peridotites from the MARK (Mid-Atlantic Ridge, Kane Fracture Zone) area were examined to understand the conditions of serpentinization and evaluate this process as a sink for seawater sulfur. The serpentinites contain a sulfur-rich secondary mineral assemblage and have high sulfur contents (up to 1 wt.%) and elevated ??34Ssulfide (3.7 to 12.7???). Geochemical reaction modeling indicates that seawater-peridotite interaction at 300 to 400??C alone cannot account for both the high sulfur contents and high ??34Ssulfide. These require a multistage reaction with leaching of sulfide from subjacent gabbro during higher temperature (???400??C) reactions with seawater and subsequent deposition of sulfide during serpentinization of peridotite at ???300??C. Serpentinization produces highly reducing conditions and significant amounts of H2 and results in the partial reduction of seawater carbonate to methane. The latter is documented by formation of carbonate veins enriched in 13C (up to 4.5???) at temperatures above 250??C. Although different processes produce variable sulfur isotope effects in other oceanic serpentinites, sulfur is consistently added to abyssal peridotites during serpentinization. Data for serpentinites drilled and dredged from oceanic crust and from ophiolites indicate that oceanic peridotites are a sink for up to 0.4 to 6.0 ?? 1012 g seawater S yr-1. This is comparable to sulfur exchange that occurs in hydrothermal systems in mafic oceanic crust at midocean ridges and on ridge flanks and amounts to 2 to 30% of the riverine sulfate source and sedimentary sulfide sink in the oceans. The high concentrations and modified isotope compositions of sulfur in serpentinites could be important for mantle metasomatism during subduction of crust generated at slow spreading rates. ?? 2003 Elsevier Science Ltd.

Localization of Epileptogenic Zones using Partical Volume Corrected FDG Uptake on FDG PET and Voxel Based Morphometry on MRI

Energy Technology Data Exchange (ETDEWEB)

Kang, Won Jun; Lee, Ho Young; Lee, Jae Sung; Lee, Dong Soo; Lee, Sang Kun; Chung, June Key; Lee, Myung Chul [College of Medicine, Univ. of Seoul National, Seoul (Korea, Republic of)

2003-07-01

Partial volume corrected (PVC) FDG uptake yields information about regional metabolic level void of volume change, and voxel based morphometry (VBM) yields objective information regarding gray matter concentration. We investigated the roles of PVC PET and VBM to localize epileptogenic zones in medial temporal lobe epilepsy (mTLE) and non-lesional neocortical epilepsy. As a control group for PVC, 40 normal volunteers without history of neurologic or psychiatric diseases underwent FDG PET and MRI. Seventeen mTLE patients (M: F=7: 10, age=309 y) and nine neocortical epilepsy patients (M: F=6: 3, age=246, lateral temporal: 5, frontal: 3, occipital: 1) confirmed by surgery or epilepsy board meeting were enrolled. Standard VBM analysis was performed using individual MRI images compared with those of age-matched controls. For PVC, FDG PET was co-registered with its own MRI. PVC PET was obtained by dividing spillover-corrected PET by smoothed gray matter image pixel by pixel. SPAM was applied as a mask of volume of interest (VOI) to calculate gyral FDG uptake on PVC-FDG PET. Hippocampus, amygdala, superior, middle, inferior temporal gyrus and parahippocampal gyrus were the gyral SPAM VOIs in mTLE. Globally normalized PVC-FDG counts were compared with those of age-matched controls in mTLE and neocortical epilepsy patients. In mTlE, PVC-FDG PET correctly localized epileptogenic zones with the accuracy of 76% (13/17) in hippocampus and 82% (14/17) in any of six regions. VBM correctly localized 59% (10/17) in mTLE. In neocortical epilepsy, PVC-FDG PET localized epileptogenic zones in 44%, and VBM in 33%, Using VBM and PVC-FDG PET altogether, epileptogenic zones were localized in 66% (6/9). In mTLE, gyral PVC FDG uptake of temporal lobes was useful in localizing epileptogenic zones by demonstrating partial volume-void FDG concentration. In non-lesional cryptogenic neocortical epilepsy, combination of PVC-FDG PET and VBM is recommended to localize epileptogenic zones.

Implant-tooth-supported fixed partial prostheses: correlations between in vivo occlusal bite forces and marginal bone reactions.

Science.gov (United States)

Akça, Kivanç; Uysal, Serdar; Cehreli, Murat Cavit

2006-06-01

To evaluate maximal occlusal bite forces (MOF) and marginal bone level (MBL) changes in patients with implant-tooth-supported fixed partial prostheses (FPP). Twenty nine partially edentulous patients consecutively who received 34 three-occlusal unit FPP with terminal implant and tooth support were subjected to quantification of MOFs using a sub-miniature load cell connected to a data acquisition system and measurement of the MBL changes around implants in digitalized periapical radiographs obtained at prostheses delivery and 24-month follow-up. MOFs for implant support (mean: 353.61 N) significantly differed from tooth support (mean: 275.48 N) (P 0.05). MBL changes at mesial and distal sites of the implants at 24 months of functional loading were 0.28 and 0.097 mm respectively. Although MOFs under functional loading might indicate an increase in load participation for supporting implant, the rigid connection between implant and natural tooth via three-occlusal unit FPP does not jeopardize the time-dependent MBL stability of the implant under functional loads.

FY 2000 Annual Report for EMSP Project No.70108 - Effects of Fluid Distribution on Measured Geophysical Properties for Partially Saturated, Shallow Subsurface Conditions

International Nuclear Information System (INIS)

Berge, P.A.; Bonner, B.P.; Roberts, J.J.; Wildenschild, D.; Aracne-Ruddle, C.M.; Berryman, J.G.; Bertete-Aguirre, H.; Boro, C.O.; Carlberg, E.D.

2000-01-01

Our goal is to improve geophysical imaging of the vadose zone. We will achieve this goal by providing new methods to improve interpretation of field data. The purpose of this EMSP project is to develop relationships between laboratory measured geophysical properties and porosity, saturation, and fluid distribution, for partially saturated soils. Algorithms for relationships between soil composition, saturation, and geophysical measurements will provide new methods to interpret geophysical field data collected in the vadose zone at sites such as Hanford, WA. This report summarizes work after 10 months of a 3-year project. We have modified a laboratory ultrasonics apparatus developed in a previous EMSP project (No.55411) so that we can make velocity measurements for partially-saturated samples rather than fully-saturated or dry samples. We are testing the measurement apparatus using standard laboratory sand samples such as Ottawa sand samples. Preliminary results indicate that we can measure both compressional and shear velocities in these sand samples. We have received Hanford soil samples (sands from split-spoon cores from an uncontaminated site) and expect to make ultrasonic measurements on them also. We have used the LLNL x-ray facility to perform x-ray computed tomography (XCT) imaging for several partially-saturated Ottawa sand and Lincoln sand samples, and have also used the DOE Advance Photon Source at Argonne National Laboratory to make higher-resolution images of some sand samples. Preliminary results indicate that we can image amount and distribution of fluids in homogeneous sand samples. Continuing work from the previous EMSP project, we are testing a new data analysis method for seismic data that is expected to improve interpretation of seismic data from the vadose zone by showing how partial saturation affects seismic parameters. Our results suggest that the planned approach for this research is appropriate, that microstructure is an important factor

Slip Zone versus Damage Zone Micromechanics, Arima-Takasuki Tectonic Line, Japan

Science.gov (United States)

White, J. C.; Lin, A.

2017-12-01

The Arima-Takasuki Tectonic Line (ATTL) of southern Honshu, Japan is defined by historically active faults and multiple splays producing M7 earthquakes. The damage zone of the ATTL comprises a broad zone of crushed, comminuted and pulverized granite/rhyolite1,2containing cm-scale slip zones and highly comminuted injection veins. In this presentation, prior work on the ATTL fault rocks is extending to include microstructural characterization by transmission electron microscopy (TEM) from recent trenching of the primary slip zone, as well as secondary slip zones. This is necessary to adequately characterize the extremely fine-grained material (typically less than 1mm) in both damage and core zones. Damage zone material exhibits generally random textures3 whereas slip zones are macroscopically foliated, and compositionally layered, notwithstanding a fairly homogeneous protolith. The latter reflects fluid-rock interaction during both coseismic and interseismic periods. The slip zones are microstructurally heterogeneous at all scales, comprising not only cataclasites and phyllosilicate (clay)-rich gouge zones, but Fe/Mn pellets or clasts that are contained within gouge. These structures appear to have rolled and would suggest rapid recrystallization and/or growth. A central question related to earthquake recurrence along existing faults is the nature of the gouge. In both near-surface exposures and ongoing drilling at depth, "plastic" or "viscous" gouge zones comprise ultra-fine-grained clay-siliciclastic particles that would not necessarily respond in a simple frictional manner. Depending on whether the plastic nature of these slip zones develops during or after slip, subsequent focusing of slip within them could be complicated. 1 Mitchell, T.A., Ben-Zion, Y., Shimamoto, T., 2011. Ear. Planet. Sci. Lett. 308, 284-297. 2 Lin, A., Yamashita, K, Tanaka, M. J., 2013. Struc. Geol. 48, 3-13. 3 White, J.C., Lin, A. 2016. Proc. AGU Fall Mtg., T42-02 San Francisco.

Giant partially thrombosed 4 th ventricular posterior inferior cerebellar artery aneurysm; microsurgical management

Directory of Open Access Journals (Sweden)

Forhad Hossain Chowdhury

2014-01-01

Full Text Available A 42-year-old woman presented with a 3-month history of progressive occipital headache, vomiting, walking difficulty, and repeated fall. She had no history of sudden and severe headache. She had positive cerebellar signs, predominantly on the right side. Computerized tomography (CT scan, CT angiogram, and magnetic resonance image (MRI of the brain showed suspected partially thrombosed giant 4 th ventricular posterior inferior cerebellar artery aneurysm. Patient developed severe hypersensitivity reaction during both CT scan and MRI after contrast injection. Though needed, digital subtraction angiogram (DSA of cerebral vessels was not done. The aneurysm was managed by microsurgical clipping of the aneurysm neck and partial excision of thrombosed aneurysm. Here, we report the details of management of these difficult giant aneurysm without DSA.

Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Transport from the Membrane to the Packed Bed

NARCIS (Netherlands)

van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

2007-01-01

With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

Effect of mass-transport limitations on the performance of a packed bed membrane reactor for partial oxidations. Transport from the membrane to the packed bed

NARCIS (Netherlands)

Sint Annaland, van M.; Kurten, U.; Kuipers, J.A.M.

2007-01-01

With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

Experts' understanding of partial derivatives using the Partial Derivative Machine

OpenAIRE

Roundy, David; Dorko, Allison; Dray, Tevian; Manogue, Corinne A.; Weber, Eric

2014-01-01

Partial derivatives are used in a variety of different ways within physics. Most notably, thermodynamics uses partial derivatives in ways that students often find confusing. As part of a collaboration with mathematics faculty, we are at the beginning of a study of the teaching of partial derivatives, a goal of better aligning the teaching of multivariable calculus with the needs of students in STEM disciplines. As a part of this project, we have performed a pilot study of expert understanding...

Evaluation of Ohio work zone speed zones process.

Science.gov (United States)

2014-06-01

This report describes the methodology and results of analyses performed to determine the effectiveness of Ohio Department of Transportation processes for establishing work zone speed zones. Researchers observed motorists speed choice upstream of a...

Finite-rate chemistry modelling of non-conventional combustion regimes using a Partially-Stirred Reactor closure: combustion model formulation and implementation details

OpenAIRE

Li, Zhiyi; Ferrarotti, Marco; Cuoci, Alberto; Parente, Alessandro

2018-01-01

The present work focuses on the numerical simulation ofModerate or Intense Low oxygen Dilution combustion condition, using thePartially-Stirred Reactor model for turbulence-chemistry interactions.The Partially-Stirred Reactor model assumes that reactions are confinedin a specific region of the computational cell, whose mass fractiondepends both on the mixing and the chemical time scales. Therefore, theappropriate choice of mixing and chemical time scales becomes crucial toensure the accuracy ...

Flow pathways in the evolving critical zone - insights from hydraulic groundwater theory

Science.gov (United States)

Harman, C. J.; Cosans, C.; Kim, M.

2017-12-01

The geochemical signatures of the evolving critical zone are delivered into streams via saturated lateral flow through hillslopes. Here we will draw on hydraulic groundwater theory and scaling arguments to obtain insights into the first-order controls on the transition from vertical infiltration to lateral flow in the critical zone. Hydraulic groundwater theory aims to provide a simplified description of unconfined, saturated groundwater flow in systems that are substantially larger in lateral than vertical extent. The theory rests on the Dupuit assumptions, which are often erroneously stated as including an assumption of exclusively lateral flow. In fact the full three-dimensional flow field can be approximated from these assumptions. Building on this theory, we examine how overall hillslope structure (slope, permeability, convergence/divergence etc.) determines the direction and magnitude of flow in the vicinity of weathering fronts in the critical zone, and how weathering products are delivered to the hillslope base. The results demonstrate that under certain conditions the mere presence of lateral flow will not disturb the lateral symmetry of reaction fronts along the hillslope. Furthermore, coupling to a simple reaction model with porosity/permeability feedback allows us to examine the implications for weathering front advance where saturated lateral flow occurs as a transient perched aquifer at the weathering front. The overall rate of weathering front advance is found to be primarily determined by the component of flow normal to the weathering front, and only significantly accelerated by the lateral component above the weathering front when parent rock permeability is very low.

Geochemical Processes Controlling Migration of High Level Wastes in Hanford's Vadose Zone

International Nuclear Information System (INIS)

Zachara, John M.; Serne, R. Jeffrey; Freshley, Mark D.; Mann, Frederick M.; Anderson, Frank J.; Wood, Marcus I.; Jones, Thomas E.; Myers, David A.

2007-01-01

High level nuclear wastes (HLW) from Hanford's plutonium reprocessing are stored in massive, buried, single-shell tanks in eighteen tank farms. The wastes were initially hot because of radioactive decay, and many exhibited extreme chemical character in terms of pH, salinity, and radionuclide concentration. At present, 67 of the 149 single shell tanks are suspected to have released over 1.9 million L of tank waste to the vadose zone, with most leak events occurring between 1950 and 1975. Boreholes have been placed through the largest vadose zone plumes to define the extent of contaminant migration, and to develop conceptual models of processes governing the transformation, retardation, and overall transport of tank waste residuals. Laboratory studies with sediments so collected have shown that ion exchange, precipitation and dissolution, and surface complexation reactions have occurred between the HLW and subsurface sediments moderating their chemical character, and retarding the migration of select contaminants. Processes suspected to facilitate the far-field migration of immobile radionuclides including stable aqueous complex formation and mobile colloids were found to be potentially operative, but unlikely to occur in the field, with the exception of cyanide-facilitated migration of 60Co. Fission product oxyanions are the most mobile of tank waste constituents because their adsorption is suppressed by large concentrations of waste anions; the vadose zone clay fraction is negative in surface charge; and, unlike Cr, their reduced forms are unstable in oxidizing environments. Reaction/process-based transport modeling is beginning to be used for predictions of future contaminant mobility and plume evolution

Fault zone architecture of the San Jacinto fault zone in Horse Canyon, southern California: A model for focused post-seismic fluid flow and heat transfer in the shallow crust

Science.gov (United States)

Morton, Nissa; Girty, Gary H.; Rockwell, Thomas K.

2012-05-01

We report results of a new study of the architecture of the San Jacinto fault zone in Horse Canyon, California, where stream incision has exposed a nearly continuous outcrop of the fault zone at ~ 0.4 km depth. The fault zone at this location consists of a fault core, transition zone, damage zone, and tonalitic wall rocks. We collected and analyzed samples for their bulk and grain density, geochemical data, clay mineralogy, and textural and modal mineralogy. Progressive deformation within the fault zone is characterized by mode I cracking, subsequent shearing of already fractured rock, and cataclastic flow. Grain comminution advances towards the strongly indurated cataclasite fault core. Damage progression towards the core is accompanied by a decrease in bulk and grain density, and an increase in porosity and dilational volumetric strain. Palygorskite and mixed-layer illite/smectite clay minerals are present in the damage and transition zones and are the result of hydrolysis reactions. The estimated percentage of illite in illite/smectite increases towards the fault core where the illite/smectite to illite conversion is complete, suggesting elevated temperatures that may have reached 150 °C. Chemical alteration and elemental mass changes are observed throughout the fault zone and are most pronounced in the fault core. We conclude that the observed chemical and mineralogical changes can only be produced by the interaction of fractured wall rocks and chemically active fluids that are mobilized through the fault zone by thermo-pressurization during and after seismic events. Based on the high element mobility and absence of illite/smectite in the fault core, we expect that the greatest water/rock ratios occur within the fault core. These results indicate that hot pore fluids circulate upwards through the fractured fault core and into the surrounding damage zone. Though difficult to constrain, we speculate that the site studied during this investigation may represent

Partial resistance to stripe rust and its effect on sustainability of wheat yield

International Nuclear Information System (INIS)

Qamar, M.; Din, R.U.; Gardazi, D.A.

2014-01-01

Stripe rust (Puccinia striiformis Westend. f. sp. tritici) poses a serious threat to wheat production in cooler areas of Pakistan. The 70% area of wheat in Pakistan is prone to stripe rust disease. It can cause 10-17% yield losses if susceptible cultivars are planted under favorable conditions. Level of partial plant resistance in bread wheat and its impact on sustainable wheat production was studied at the National Agricultural Research Centre, Islamabad under natural conditions in the field. Eleven Pakistani commercial wheat cultivars/advance lines including check (Inqalab 91) were assessed for the level of partial resistance against stripe rust using Area Under the Disease Progress Curve (AUDPC), disease severity (DS) and epidemic growth rate in comparison with wheat cultivar, Inqalab 91. During 2007 cropping season, natural epidemic was developed and relative AUDPC was recorded from 0 to 100% whereas the 2008 cropping season was dry and no stripe rust appeared. Two advanced lines (NR 268 and NR 285) showed the infection type (IT) less than 7 (incompatible reaction) to the mixture of prevailing stripe rust inoculums. Very low level of DS and AUDPC were recorded in the remaining cultivars/lines indicating a high level of partial resistance to stripe rust compared to the susceptible check cultivar, Inqalab 91. Among eight cultivars/lines that showed compatible type of reaction (IT greater then equal to 7), one was resistant (relative AUDPC = 20% of Inqalab 91) and six showed very high resistance levels (relative AUDPC greater then equal to 5%). Maximum level of resistance (relative AUDPC = 0.1%) was observed in advanced line, NR 271. The wheat cultivars/lines that showed a slow disease development (low DS and AUDPC), could be considered as -1 partially resistant for stripe rust infection. The yield (2178 kg ha) of susceptible check cultivar Inqalab-91 during 2007 was reduced to 45% as -1 compared to its yield (3945 kg ha) in epidemic free year (2008). Thus the use

An Exact Solution for the Assessment of Nonequilibrium Sorption of Radionuclides in the Vadose Zone

International Nuclear Information System (INIS)

Drake, R. L.; Chen, J-S.

2002-01-01

In a report on model evaluation, the authors ran the HYDRUS Code, among other transport codes, to evaluate the impacts of nonequilibrium sorption sites on the time-evolution of 99Tc and 90Sr through the vadose zone. Since our evaluation was based on a rather low, annual recharge rate, many of the numerical results derived from HYDRUS indicated that the nonequilibrium sorption sites, in essence, acted as equilibrium sorption sites. To help explain these results, we considered a ''stripped-down'' version of the HYDRUS system. This ''stripped-down'' version possesses two dependent variables, one for the radionuclides in solution and the other for the radionuclides adsorbed to the nonequilibrium sites; and it possesses constant physical parameters. The resultant governing equation for the radionuclides in solution is a linear, advection-dispersion-reaction (i.e., radioactive decay) partial differential equation containing a history integral term accounting for the nonequilibrium sorption sites. It is this ''stripped-down'' version, which is the subject of this paper. We found an exact solution to this new version of the model. The exact solution is given in terms of a single definite integral of terms involving elementary functions of the independent variables and the system parameters. This integral possesses adequate convergence properties and is easy to evaluate, both in a quantitative matter and in a qualitative manner. The parameters that are considered in the system are as follows: the radionuclide's equilibrium partition coefficient between water and soil, the bulk density of the soil, the fractions of equilibrium/nonequilibrium sorption sites, the volumetric water content, the first order equilibrium adsorption rate constant, the first order radioactive decay rate constant, the liquid water soil tortuosity factor, the molecular diffusion coefficient in water, the longitudinal dispersivity factor, and the Darcian fluid flux density. In addition, the system

GC of catalytic reactions products involved in the promising fuel synthesis

Energy Technology Data Exchange (ETDEWEB)

Zheivot, V.; Sazonova, N. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Boreskov Inst. of Catalysis

2012-09-15

Catalytic reactions involved in the synthesis of the promising kinds of novel fuel and products formed in these reactions were systematized according to the resulting fuel type. Generalization of the retention of the substances comprising these products is presented. Chromatograms exhibiting their separation on chromatographic materials with the surface of different chemical properties are summarized. We propose procedures for gas-chromatographic analysis of the catalytic reactions products formed in the synthesis of hydrogen, methanol, dimethyl ether and hydrocarbons as a new generation of fuel alternative to petroleum and coal. For partial oxidation of methane into synthesis gas, on-line determination of the components obtained in the reaction was carried out by gas chromatography and gas analyzer based on different physicochemical methods (IR spectroscopy and electrochemical methods). Similarity of the results obtained using these methods is demonstrated. (orig.)

Fluid flow and permeabilities in basement fault zones

Science.gov (United States)

Hollinsworth, Allan; Koehn, Daniel

2017-04-01

Fault zones are important sites for crustal fluid flow, specifically where they cross-cut low permeability host rocks such as granites and gneisses. Fluids migrating through fault zones can cause rheology changes, mineral precipitation and pore space closure, and may alter the physical and chemical properties of the host rock and deformation products. It is therefore essential to consider the evolution of permeability in fault zones at a range of pressure-temperature conditions to understand fluid migration throughout a fault's history, and how fluid-rock interaction modifies permeability and rheological characteristics. Field localities in the Rwenzori Mountains, western Uganda and the Outer Hebrides, north-west Scotland, have been selected for field work and sample collection. Here Archaean-age TTG gneisses have been faulted within the upper 15km of the crust and have experienced fluid ingress. The Rwenzori Mountains are an anomalously uplifted horst-block located in a transfer zone in the western rift of the East African Rift System. The north-western ridge is characterised by a tectonically simple western flank, where the partially mineralised Bwamba Fault has detached from the Congo craton. Mineralisation is associated with hydrothermal fluids heated by a thermal body beneath the Semliki rift, and has resulted in substantial iron oxide precipitation within porous cataclasites. Non-mineralised faults further north contain foliated gouges and show evidence of leaking fluids. These faults serve as an analogue for faults associated with the Lake Albert oil and gas prospects. The Outer Hebrides Fault Zone (OHFZ) was largely active during the Caledonian Orogeny (ca. 430-400 Ma) at a deeper crustal level than the Ugandan rift faults. Initial dry conditions were followed by fluid ingress during deformation that controlled its rheological behaviour. The transition also altered the existing permeability. The OHFZ is a natural laboratory in which to study brittle fault

Gravity Effects Observed In Partially Premixed Flames

Science.gov (United States)

Puri, Ishwar K.; Aggarwal, Suresh K.; Lock, Andrew J.; Gauguly, Ranjan; Hegde, Uday

2003-01-01

Partially premixed flames (PPFs) contain a rich premixed fuel air mixture in a pocket or stream, and, for complete combustion to occur, they require the transport of oxidizer from an appropriately oxidizer-rich (or fuel-lean) mixture that is present in another pocket or stream. Partial oxidation reactions occur in fuel-rich portions of the mixture and any remaining unburned fuel and/or intermediate species are consumed in the oxidizer-rich portions. Partial premixing, therefore, represents that condition when the equivalence ratio (phi) in one portion of the flowfield is greater than unity, and in another section its value is less than unity. In general, for combustion to occur efficiently, the global equivalence ratio is in the range fuel-lean to stoichiometric. These flames can be established by design by placing a fuel-rich mixture in contact with a fuel-lean mixture, but they also occur otherwise in many practical systems, which include nonpremixed lifted flames, turbulent nonpremixed combustion, spray flames, and unwanted fires. Other practical applications of PPFs are reported elsewhere. Although extensive experimental studies have been conducted on premixed and nonpremixed flames under microgravity, there is a absence of previous experimental work on burner stabilized PPFs in this regard. Previous numerical studies by our group employing a detailed numerical model showed gravity effects to be significant on the PPF structure. We report on the results of microgravity experiments conducted on two-dimensional (established on a Wolfhard-Parker slot burner) and axisymmetric flames (on a coannular burner) that were investigated in a self-contained multipurpose rig. Thermocouple and radiometer data were also used to characterize the thermal transport in the flame.

Palm H-FAME Production through Partially Hydrogenation using Nickel/Carbon Catalyst to Increase Oxidation Stability

Directory of Open Access Journals (Sweden)

Ramayeni Elsa

2018-01-01

Full Text Available One of the methods to improve the oxidation stability of palm biodiesel is through partially hydrogenation. The production using Nickel/Carbon catalyst to speed up the reaction rate. Product is called Palm H-FAME (Hydrogenated FAME. Partial hydrogenation breaks the unsaturated bond on FAME (Fatty Acid Methyl Ester, which is a key component of the determination of oxidative properties. Changes in FAME composition by partial hydrogenation are predicted to change the oxidation stability so it does not cause deposits that can damage the injection system of diesel engine, pump system, and storage tank. Partial hydrogenation is carried out under operating conditions of 120 °C and 6 bar with 100:1, 100:3, 100:5, 100:10 % wt catalyst in the stirred batch autoclave reactor. H-FAME synthesis with 100:5 % wt Ni/C catalyst can decrease the iodine number which is the empirical measure of the number of unsaturated bonds from 91.78 to 82.38 (g-I2/100 g with an increase of oxidation stability from 585 to 602 minutes.

Measurement of the γγ partial width of the χ2 charmonium resonance

International Nuclear Information System (INIS)

Armstrong, T.A.; Bettoni, D.; Bharadwaj, V.; Biino, C.; Borreani, G.; Broemmelsiek, D.; Buzzo, A.; Calabrese, R.; Ceccucci, A.; Cester, R.; Church, M.; Dalpiaz, P.; Dalpiaz, P.F.; Dibenedetto, R.; Dimitroyannis, D.; Fabbri, M.; Fast, J.; Gianoli, A.; Ginsburg, C.M.; Gollwitzer, K.; Hahn, A.; Hasan, M.A.; Hsueh, S.; Lewis, R.; Luppi, E.; Macri, M.; Majewska, A.M.; Mandelkern, M.; Marchetto, F.; Marinelli, M.; Marques, J.; Marsh, W.; Martini, M.; Masuzawa, M.; Menichetti, E.; Migliori, A.; Mussa, R.; Palestini, S.; Pallavicini, M.; Pastrone, N.; Patrignani, C.; Peoples, J. Jr.; Pesando, L.; Petrucci, F.; Pia, M.G.; Rapidis, P.A.; Ray, R.; Reid, J.; Rinaudo, G.; Roccuzzo, B.; Rosen, J.; Santroni, A.; Sarmiento, M.; Savrie, M.; Scalisi, A.; Schultz, J.; Seth, K.K.; Smith, A.; Smith, G.A.; Sozzi, M.; Trokenheim, S.; Weber, M.F.; Werkema, S.; Zhang, Y.; Zhao, J.; Zioulas, G.

1993-01-01

The E760 Collaboration has studied the reaction bar pp→χ 2 →γγ using a hydrogen gas jet target in the Fermilab antiproton acumulator ring. The following values are obtained for the branching ratio and partial width to two photons; B(χ 2 →γγ)=(1.60±0.45)x10 -4 and Γ(χ 2 →γγ)=321±95 eV

A Gibbs Energy Minimization Approach for Modeling of Chemical Reactions in a Basic Oxygen Furnace

Science.gov (United States)

Kruskopf, Ari; Visuri, Ville-Valtteri

2017-12-01

In modern steelmaking, the decarburization of hot metal is converted into steel primarily in converter processes, such as the basic oxygen furnace. The objective of this work was to develop a new mathematical model for top blown steel converter, which accounts for the complex reaction equilibria in the impact zone, also known as the hot spot, as well as the associated mass and heat transport. An in-house computer code of the model has been developed in Matlab. The main assumption of the model is that all reactions take place in a specified reaction zone. The mass transfer between the reaction volume, bulk slag, and metal determine the reaction rates for the species. The thermodynamic equilibrium is calculated using the partitioning of Gibbs energy (PGE) method. The activity model for the liquid metal is the unified interaction parameter model and for the liquid slag the modified quasichemical model (MQM). The MQM was validated by calculating iso-activity lines for the liquid slag components. The PGE method together with the MQM was validated by calculating liquidus lines for solid components. The results were compared with measurements from literature. The full chemical reaction model was validated by comparing the metal and slag compositions to measurements from industrial scale converter. The predictions were found to be in good agreement with the measured values. Furthermore, the accuracy of the model was found to compare favorably with the models proposed in the literature. The real-time capability of the proposed model was confirmed in test calculations.

Kinetic Modeling of the Reaction Rate for Quartz and Carbon Black Pellet

Science.gov (United States)

Li, Fei; Tangstad, Merete

2018-06-01

The kinetic modeling for the carbothermal reduction reaction rate in quartz and carbon black pellets is studied at different temperatures, under varying CO partial pressures in ambient atmosphere, varying carbon contents, different quartz particle sizes, and different crucible opening areas. Carbon black is produced by the cracking of natural gas. The activation energy of the SiC-producing step was determined to be 594 kJ/mol. The averaged pre-exponential factor A obtained from 1898 K, 1923 K, and 1948 K (1625 °C, 1650 °C, and 1675 °C) is 2.62E+16 min-1. The reaction rate of the gas-solid interface factor, fix-C content ( X fix-C), temperature ( T), and CO partial pressure ( X CO) can be expressed as follows: {{d/pct}}{{{d}t}} = (1 - 0.40 × X_{{{fix} - C}}^{ - 0.86} × {pct}) × 2.62 × 10^{16} × \\exp ( { - 594000/RT} ) × (2.6 - 0.015 × X_{co} ).

Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

Directory of Open Access Journals (Sweden)

Jacques C. Védrine

2016-01-01

Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

Radiation reaction for spinning bodies in effective field theory. I. Spin-orbit effects

Science.gov (United States)

Maia, Natália T.; Galley, Chad R.; Leibovich, Adam K.; Porto, Rafael A.

2017-10-01

We compute the leading post-Newtonian (PN) contributions at linear order in the spin to the radiation-reaction acceleration and spin evolution for binary systems, which enter at fourth PN order. The calculation is carried out, from first principles, using the effective field theory framework for spinning compact objects, in both the Newton-Wigner and covariant spin supplementary conditions. A nontrivial consistency check is performed on our results by showing that the energy loss induced by the resulting radiation-reaction force is equivalent to the total emitted power in the far zone, up to so-called "Schott terms." We also find that, at this order, the radiation reaction has no net effect on the evolution of the spins. The spin-spin contributions to radiation reaction are reported in a companion paper.

Bayesian inversion analysis of nonlinear dynamics in surface heterogeneous reactions.

Science.gov (United States)

Omori, Toshiaki; Kuwatani, Tatsu; Okamoto, Atsushi; Hukushima, Koji

2016-09-01

It is essential to extract nonlinear dynamics from time-series data as an inverse problem in natural sciences. We propose a Bayesian statistical framework for extracting nonlinear dynamics of surface heterogeneous reactions from sparse and noisy observable data. Surface heterogeneous reactions are chemical reactions with conjugation of multiple phases, and they have the intrinsic nonlinearity of their dynamics caused by the effect of surface-area between different phases. We adapt a belief propagation method and an expectation-maximization (EM) algorithm to partial observation problem, in order to simultaneously estimate the time course of hidden variables and the kinetic parameters underlying dynamics. The proposed belief propagation method is performed by using sequential Monte Carlo algorithm in order to estimate nonlinear dynamical system. Using our proposed method, we show that the rate constants of dissolution and precipitation reactions, which are typical examples of surface heterogeneous reactions, as well as the temporal changes of solid reactants and products, were successfully estimated only from the observable temporal changes in the concentration of the dissolved intermediate product.

Impacts of Severe Weather, Climate Zone, and Energy Factors on Base Realignment and Closure (BRAC)

Science.gov (United States)

2015-03-26

Partial Fulfillment of the Requirements for the Degree of Master of Science in Engineering Management Christopher L. Teke, Major, USAF Major...the science behind severe weather occurrences and climate zone. Chapter 3 further details the methodology used in the analysis and sets the stage... actuarial estimates and should be thought of as insurance premiums, and ought to remain a budgeted cost if a base stays open. In contrast, if a base is

Mechanism to preserve phrenic nerve function during photosensitization reaction: drug uptake and photosensitization reaction effect on electric propagation

Science.gov (United States)

Takahashi, Haruka; Hamada, Risa; Ogawa, Emiyu; Arai, Tsunenori

2018-02-01

To study a mechanism of phrenic nerve preservation phenomena during a photosensitization reaction, we investigated an uptake of talaporfin sodium and photosensitization reaction effect on an electric propagation. Right phrenic nerve was completely preserved after superior vena cava isolations using the photosensitization reaction in canine animal experiments, in spite of adjacent myocardium was electrically blocked. We predicted that low drug uptake and/or low photosensitization reaction effect on the nerve might be a mechanism of that phenomena. To investigate uptake to various nerve tissue, a healthy extracted crayfish ventral nerve cord and an extracted porcine phrenic nerve were immersed in 20 μg/ml talaporfin sodium solution for 0-240 min. The mean talaporfin sodium fluorescence brightness increased depending on the immersion time. This brightness saturated around the immersion time of 120 min. We found that talaporfin sodium uptake inside the perineurium which directly related to the electric propagation function was lower than that of outside in the porcine phrenic nerve. To investigate photosensitization reaction effect on electric propagation, the crayfish nerve was immersed into the same solution for 15 min and irradiated by a 663 nm laser light with 120 mW/cm2. Since we found the action potential disappeared when the irradiation time was 25-65 s, we consider that the crayfish nerve does not tolerant to the photosensitization reaction on electric propagation function at atmospheric pressure. From these results, we think that the low uptake of talaporfin sodium inside the perineurium and low oxygen partial pressure of nerve might be the possible mechanism to preserve phrenic nerve in vivo.

International Network of Nuclear Reaction Data Centres

International Nuclear Information System (INIS)

Otsuka, Naohiko; Dunaeva, Svetlana

2010-11-01

The activities of fourteen nuclear data centres are summarized, and their cooperation under the auspices of the International Atomic Energy Agency is described. Each of the centres provides coverage for different geographical zones and/or specific types of nuclear data, thus together providing a complete service for users worldwide. The International Network of Nuclear Reaction Data Centres (NRDC) was established with the objective of providing nuclear physics databases that are required for nuclear technology (encompassing energy and non-energy applications) by coordinating the collection, compilation and dissemination of nuclear data on an international scale. (author)

A system for incubations at high gas partial pressure

Directory of Open Access Journals (Sweden)

Patrick eSauer

2012-02-01

Full Text Available High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed one MPa at in-situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in-situ conditions, but the partial pressure of dissolved gasses has to be controlled as well.We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120° C and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. The system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g. fluid-gas-rock-interactions in relation to carbon dioxide sequestration.As an application of the system we extracted organic acids from sub-bituminous coal using H2O as well as a H2O-CO2 mixture at elevated temperature (90°C and pressure (5 MPa. Subsamples were taken during the incubation and analysed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could detect an increase in sulphate reduction rate upon the addition of

Type-Directed Partial Evaluation

DEFF Research Database (Denmark)

Danvy, Olivier

1998-01-01

Type-directed partial evaluation uses a normalization function to achieve partial evaluation. These lecture notes review its background, foundations, practice, and applications. Of specific interest is the modular technique of offline and online type-directed partial evaluation in Standard ML...

Type-Directed Partial Evaluation

DEFF Research Database (Denmark)

Danvy, Olivier

1998-01-01

Type-directed partial evaluation uses a normalization function to achieve partial evaluation. These lecture notes review its background, foundations, practice, and applications. Of specific interest is the modular technique of offline and online type-directed partial evaluation in Standard ML of ...

Investigation of (n,γ) reactions in fissionable fluids in a hybrid reactor system

International Nuclear Information System (INIS)

Guenay, Mehtap

2014-01-01

In this study, the effect of (n,γ) reactions in spent fuel-grade (SFG)-PuO 2 , UO 2 , NpO 2 and UCO contents was investigated in a designed hybrid reactor system. In this system, the molten salt-heavy metal mixtures 93 - 85 % Li 20 Sn 80 + 5 % SFG-PuO 2 and 2 - 10 % UO 2 , 93 - 85 % Li 20 Sn 80 + 5 % SFG-PuO 2 and 2 - 10 % NpO 2 , 93 - 85 % Li 20 Sn 80 + 5 % SFG-PuO 2 and 2 - 10 % UCO were used as fluids. Beryllium (Be) is used as neutron multiplier by (n,2n) reactions. Thence, a Be zone with a width of 3 cm was used in order to contribute on fissile fuel breeding between the liquid first wall and blanket. (n,γ) reactions were calculated in the liquid first wall, blanket and shield zones, which SFG-PuO 2 , UO 2 , NpO 2 and UCO contents. 9Cr2WVTa ferritic steel with the width of 4 cm was used as the structural material. Three-dimensional nucleonic calculations were performed using the most recent version MCNPX-2.7.0 the Monte Carlo code and nuclear data library ENDF/B-VII.0. (orig.)

Strategies for catalyst development: possibilities of the ``rational approach`` illustrated with partial oxidation reactions

Energy Technology Data Exchange (ETDEWEB)

Weiss, W.; Schedel-Niedrig, T.; Schloegl, R. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany). Abt. Oberflaechenphysik

1998-12-31

The paper discusses two petrochemical selective oxidation reactions namely the practised formation of styrene (STY) and the desired oxidative functionalisation of propane. The present knowledge about the mode of operation of oxide catalysts is critically considered. The dehydrogenation of ethylbenzene (EB) should be described by an oxidehydration with water acting as oxidant. The potential role of the coke formed during catalytic reaction as co-catalyst will be discussed. Selective oxidation is connected with the participation of lattice oxygen mechanism which transforms unselective gas phase oxygen into selective oxygen. The atomistic description of this process is still quite unclear as well as the electron structural properties of the activated oxygen atom. The Role of solid state acidity as compared to the role of lattice oxygen is much less well investigated modern multiphase-multielement oxide (MMO) catalysts. The rationale is that the significant efforts made to improve current MMO systems by chemical modifications can be very much more fruitful when in a first step the mode of action of a catalyst is clarified on the basis of suitable experiments. Such time-consuming experiments at the beginning of a campaign for catalyst improvement pay back their investment in later stages of the project when strategies of chemical development can be derived on grounds of understanding. (orig.)

Dynamics of nitrate production and removal as a function of residence time in the hyporheic zone

Science.gov (United States)

Jay P. Zarnetske; Roy Haggerty; Steven M. Wondzell; Michelle A. Baker

2011-01-01

Biogeochemical reactions associated with stream nitrogen cycling, such as nitrification and denitrification, can be strongly controlled by water and solute residence times in the hyporheic zone (HZ). We used a whole-stream steady state 15N-Iabeled nitrate and conservative tracer addition to investigate the spatial and temporal physiochemical...

Synchronization of Reaction-Diffusion Neural Networks With Dirichlet Boundary Conditions and Infinite Delays.

Science.gov (United States)

Sheng, Yin; Zhang, Hao; Zeng, Zhigang

2017-10-01

This paper is concerned with synchronization for a class of reaction-diffusion neural networks with Dirichlet boundary conditions and infinite discrete time-varying delays. By utilizing theories of partial differential equations, Green's formula, inequality techniques, and the concept of comparison, algebraic criteria are presented to guarantee master-slave synchronization of the underlying reaction-diffusion neural networks via a designed controller. Additionally, sufficient conditions on exponential synchronization of reaction-diffusion neural networks with finite time-varying delays are established. The proposed criteria herein enhance and generalize some published ones. Three numerical examples are presented to substantiate the validity and merits of the obtained theoretical results.

Lattice Boltzmann analysis of effect of heating location and Rayleigh number on natural convection in partially heated open ended cavity

Energy Technology Data Exchange (ETDEWEB)

Gangawane, Krunal Madhukar; Bharti, Ram Prakash; Kumar, Surendra [Indian Institute of Technology Roorkee, Uttarakhand (India)

2015-08-15

Natural convection characteristics of a partially heated open ended square cavity have been investigated numerically by using an in-house computational flow solver based on the passive scalar thermal lattice Boltzmann method (PS-TLBM) with D2Q9 (two-dimensional and nine-velocity link) lattice model. The partial part of left wall of the cavity is heated isothermally at either of the three different (bottom, middle and top) locations for the fixed heating length as half of characteristic length (H/2) while the right wall is open to the ambient conditions. The other parts of the cavity are thermally isolated. In particular, the influences of partial heating locations and Rayleigh number (103≤ Ra≤106) in the laminar zone on the local and global natural convection characteristics (such as streamline, vorticity and isotherm contours; centerline variations of velocity and temperature; and local and average Nusselt numbers) have been presented and discussed for the fixed value of the Prandtl number (Pr=0.71). The streamline patterns show qualitatively similar nature for all the three heating cases and Rayleigh numbers, except the change in the recirculation zone which is found to be largest for middle heating case. Isotherm patterns are shifted towards a partially heated wall on increasing Rayleigh number and/or shifting of heating location from bottom to top. Both the local and average Nusselt numbers, as anticipated, shown proportional increase with Rayleigh number. The cavity with middle heating location shown higher heat transfer rate than that for the top and bottom heating cases. Finally, the functional dependence of the average Nusselt number on flow governing parameters is also presented as a closure relationship for the best possible utilization in engineering practices and design.

Systematic of the slope-mass-correlations in diffractive dissociation reactions

International Nuclear Information System (INIS)

Antunes, A.C.B.; Santoro, A.F.S.; Souza, M.H.G.

1984-01-01

A set of several results of the Three Components Deck Model for Diffractive Dissociation Reactions is presented. News and recently published results are summarized to obtain a general overview of the model, its predictions and comparison with experimental results. Two kinds of correlations and amplitudes are given: The slope-mass cos theta sup(GJ) correlation and slope-mass partial wave. (Author) [pt

Three types of element fluxes from metabasite into peridotite in analogue experiments: Insights into subduction-zone processes

Science.gov (United States)

Perchuk, A. L.; Yapaskurt, V. O.; Griffin, W. L.; Shur, M. Yu.; Gain, S. E. M.

2018-03-01

Piston-cylinder experiments with natural rocks and mineral separates were carried out at 750-900 °C and 2.9 GPa, conditions relevant to hot subduction zones, to study the mechanisms of metasomatic alteration of mantle-wedge rocks such as dunite and lherzolite, and the transfer of trace elements released from a carbonate-bearing amphibolite during its eclogitization. Element transfer from the slab to the mantle lithologies occurred in porous-, focused- and diffusive-flow regimes that remove melt and carbon, and partially water, from the metabasite layer. Porous flow is recorded by dissolution of clinopyroxene and growth of orthopyroxene ± garnet ± magnesite ± chlorite along grain boundaries in the peridotite layers, but is invisible in the metabasite layers. Porous flow of the same fluids/melts produces harzburgite mineralogy in both dunite and lherzolite. The transformation of lherzolite to harzburgite reflects breakdown of clinopyroxene in the lherzolite and diffusion of the liberated calcium into the metabasite layer, i.e. against the direction of major fluid/melt flow. Focused flow develops along the side walls of the capsules, producing a melt-free omphacite ± phengite ± quartz paragenesis in the metabasite, and melt segregations, separated from the host peridotite layers by newly-formed omphacite ± garnet ± phlogopite + orthopyroxene + magnesite. Diffusive flow leads to the formation of orthopyroxene ± magnesite ± garnet reaction zones at the metabasite-peridotite interface and some melt-peridotite interfaces. Melt segregations in the peridotite layers at 850-900 °C are rich in LREE and LILE, strongly depleted in Y and HREE, and have higher Sr/Y and La/Yb ratios than island arc andesites, dacites and rhyolites. These features, and negative anomalies in Nb-Ta and low Nb/Ta, resemble those of high-silica adakites and TTGs, but K2O is high compared to TTGs. Metasomatism in the dunite layer changes the REE patterns of dunite, recording chromatographic

Polarization Observables T and F in the yp -> pi p Reaction

Energy Technology Data Exchange (ETDEWEB)

Jiang, Hao [Univ. of South Carolina, Columbia, SC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2017-08-31

The theory that describes the interaction of quarks is Quantum Chromodynamics (QCD), but how quarks are bound inside a nucleon is not yet well understood. Pion photoproduction experiments reveal important information about the nucleon excited states and the dynamics of the quarks within it and thus provide a useful tool to study QCD. Detailed information about this reaction can be obtained in experiments that utilize polarized photon beams and polarized targets. Pion photoproduction in the γρ -> π0ρ reaction has been measured in the FROST experiment at the Thomas Jefferson National Accelerator Facility. In this experiment circularly polarized photons with electron-beam energies up to 3.082 GeV impinged on a transversely polarized frozen-spin target. Final-state protons were detected in the CEBAF Large Acceptance Spectrometer. Results of the polarization observables T and F have been extracted. The data generally agree with predictions of present partial wave analyses, but also show marked differences. The data will constrain further partial wave analyses and improve the extraction of proton resonance properties.

Fault zone hydrogeology

Science.gov (United States)

Bense, V. F.; Gleeson, T.; Loveless, S. E.; Bour, O.; Scibek, J.

2013-12-01

Deformation along faults in the shallow crust (research effort of structural geologists and hydrogeologists. However, we find that these disciplines often use different methods with little interaction between them. In this review, we document the current multi-disciplinary understanding of fault zone hydrogeology. We discuss surface- and subsurface observations from diverse rock types from unlithified and lithified clastic sediments through to carbonate, crystalline, and volcanic rocks. For each rock type, we evaluate geological deformation mechanisms, hydrogeologic observations and conceptual models of fault zone hydrogeology. Outcrop observations indicate that fault zones commonly have a permeability structure suggesting they should act as complex conduit-barrier systems in which along-fault flow is encouraged and across-fault flow is impeded. Hydrogeological observations of fault zones reported in the literature show a broad qualitative agreement with outcrop-based conceptual models of fault zone hydrogeology. Nevertheless, the specific impact of a particular fault permeability structure on fault zone hydrogeology can only be assessed when the hydrogeological context of the fault zone is considered and not from outcrop observations alone. To gain a more integrated, comprehensive understanding of fault zone hydrogeology, we foresee numerous synergistic opportunities and challenges for the discipline of structural geology and hydrogeology to co-evolve and address remaining challenges by co-locating study areas, sharing approaches and fusing data, developing conceptual models from hydrogeologic data, numerical modeling, and training interdisciplinary scientists.

Uranium removal during low discharge in the Ganges-Brahmaputra mixing zone

International Nuclear Information System (INIS)

Carroll, J.; Moore, W.S.

1993-01-01

The Ganges-Brahmaputra river system supplies more dissolved uranium to the ocean than any other system in the world (Sarin et al., 1990; Sackett et al., 1973). However, there have been no investigations to determine whether riverine supplies of uranium are altered by geochemical reactions in the river-ocean mixing zone. In this study, uranium and salinity data were collected in the Ganges-Brahmaputra mixing zone during a period of low river discharge. The uranium distribution with salinity shows that in waters <12 ppt salinity, uranium activities are significantly lower than predicted from conservative mixing of river and seawater. This suggests that uranium is being removed within the mixing zone. The behavior of uranium in the Ganges-Brahmaputra is in sharp contrast to its behavior in the Amazon mixing zone where McKee et al. (1978) found uranium activities significantly higher than predicted from conservative mixing. The contrasting behaviors for uranium in these systems are due to the different locations where mixing between river and seawater occurs. For the Amazon, mixing takes place on the continental shelf whereas for the Ganges-Brahmaputra, mixing occurs within shoreline sedimentary environments. The physiochemical processes controlling uranium removal to sediment deposits in the Amazon are partly known. The authors discuss mechanisms which may be removing uranium to suspended and mangrove sediments in the Ganges-Brahmaputra

Anatomy-based reconstruction of FDG-PET images with implicit partial volume correction improves detection of hypometabolic regions in patients with epilepsy due to focal cortical dysplasia diagnosed on MRI

Energy Technology Data Exchange (ETDEWEB)

Goffin, Karolien; Baete, Kristof; Nuyts, Johan; Laere, Koen van [University Hospital Leuven, Division of Nuclear Medicine and Medical Imaging Center, Leuven (Belgium); Van Paesschen, Wim [University Hospital Leuven, Neurology Department, Leuven (Belgium); Dupont, Patrick [University Hospital Leuven, Division of Nuclear Medicine and Medical Imaging Center, Leuven (Belgium); University Hospital Leuven, Laboratory of Cognitive Neurology, Leuven (Belgium); Palmini, Andre [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre Epilepsy Surgery Program, Hospital Sao Lucas, Porto Alegre (Brazil)

2010-06-15

Detection of hypometabolic areas on interictal FDG-PET images for assessing the epileptogenic zone is hampered by partial volume effects. We evaluated the performance of an anatomy-based maximum a-posteriori (A-MAP) reconstruction algorithm which combined noise suppression with correction for the partial volume effect in the detection of hypometabolic areas in patients with focal cortical dysplasia (FCD). FDG-PET images from 14 patients with refractory partial epilepsy were reconstructed using A-MAP and maximum likelihood (ML) reconstruction. In all patients, presurgical evaluation showed that FCD represented the epileptic lesion. Correspondence between the FCD location and regional metabolism on a predefined atlas was evaluated. An asymmetry index of FCD to normal cortex was calculated. Hypometabolism at the FCD location was detected in 9/14 patients (64%) using ML and in 10/14 patients (71%) using A-MAP reconstruction. Hypometabolic areas outside the FCD location were detected in 12/14 patients (86%) using ML and in 11/14 patients (79%) using A-MAP reconstruction. The asymmetry index was higher using A-MAP reconstruction (0.61, ML 0.49, p=0.03). The A-MAP reconstruction algorithm improved visual detection of epileptic FCD on brain FDG-PET images compared to ML reconstruction, due to higher contrast and better delineation of the lesion. This improvement failed to reach significance in our small sample. Hypometabolism outside the lesion is often present, consistent with the observation that the functional deficit zone tends to be larger than the epileptogenic zone. (orig.)

Anatomy-based reconstruction of FDG-PET images with implicit partial volume correction improves detection of hypometabolic regions in patients with epilepsy due to focal cortical dysplasia diagnosed on MRI

International Nuclear Information System (INIS)

Goffin, Karolien; Baete, Kristof; Nuyts, Johan; Laere, Koen van; Van Paesschen, Wim; Dupont, Patrick; Palmini, Andre

2010-01-01

Detection of hypometabolic areas on interictal FDG-PET images for assessing the epileptogenic zone is hampered by partial volume effects. We evaluated the performance of an anatomy-based maximum a-posteriori (A-MAP) reconstruction algorithm which combined noise suppression with correction for the partial volume effect in the detection of hypometabolic areas in patients with focal cortical dysplasia (FCD). FDG-PET images from 14 patients with refractory partial epilepsy were reconstructed using A-MAP and maximum likelihood (ML) reconstruction. In all patients, presurgical evaluation showed that FCD represented the epileptic lesion. Correspondence between the FCD location and regional metabolism on a predefined atlas was evaluated. An asymmetry index of FCD to normal cortex was calculated. Hypometabolism at the FCD location was detected in 9/14 patients (64%) using ML and in 10/14 patients (71%) using A-MAP reconstruction. Hypometabolic areas outside the FCD location were detected in 12/14 patients (86%) using ML and in 11/14 patients (79%) using A-MAP reconstruction. The asymmetry index was higher using A-MAP reconstruction (0.61, ML 0.49, p=0.03). The A-MAP reconstruction algorithm improved visual detection of epileptic FCD on brain FDG-PET images compared to ML reconstruction, due to higher contrast and better delineation of the lesion. This improvement failed to reach significance in our small sample. Hypometabolism outside the lesion is often present, consistent with the observation that the functional deficit zone tends to be larger than the epileptogenic zone. (orig.)

Construction and accuracy of partial differential equation approximations to the chemical master equation.

Science.gov (United States)

Grima, Ramon

2011-11-01

The mesoscopic description of chemical kinetics, the chemical master equation, can be exactly solved in only a few simple cases. The analytical intractability stems from the discrete character of the equation, and hence considerable effort has been invested in the development of Fokker-Planck equations, second-order partial differential equation approximations to the master equation. We here consider two different types of higher-order partial differential approximations, one derived from the system-size expansion and the other from the Kramers-Moyal expansion, and derive the accuracy of their predictions for chemical reactive networks composed of arbitrary numbers of unimolecular and bimolecular reactions. In particular, we show that the partial differential equation approximation of order Q from the Kramers-Moyal expansion leads to estimates of the mean number of molecules accurate to order Ω(-(2Q-3)/2), of the variance of the fluctuations in the number of molecules accurate to order Ω(-(2Q-5)/2), and of skewness accurate to order Ω(-(Q-2)). We also show that for large Q, the accuracy in the estimates can be matched only by a partial differential equation approximation from the system-size expansion of approximate order 2Q. Hence, we conclude that partial differential approximations based on the Kramers-Moyal expansion generally lead to considerably more accurate estimates in the mean, variance, and skewness than approximations of the same order derived from the system-size expansion.

Compatriot partiality and cosmopolitan justice: Can we justify compatriot partiality within the cosmopolitan framework?

Directory of Open Access Journals (Sweden)

Rachelle Bascara

2016-10-01

Full Text Available This paper shows an alternative way in which compatriot partiality could be justified within the framework of global distributive justice. Philosophers who argue that compatriot partiality is similar to racial partiality capture something correct about compatriot partiality. However, the analogy should not lead us to comprehensively reject compatriot partiality. We can justify compatriot partiality on the same grounds that liberation movements and affirmative action have been justified. Hence, given cosmopolitan demands of justice, special consideration for the economic well-being of your nation as a whole is justified if and only if the country it identifies is an oppressed developing nation in an unjust global order.This justification is incomplete. We also need to say why Person A, qua national of Country A, is justified in helping her compatriots in Country A over similarly or slightly more oppressed non-compatriots in Country B. I argue that Person A’s partiality towards her compatriots admits further vindication because it is part of an oppressed group’s project of self-emancipation, which is preferable to paternalistic emancipation.Finally, I identify three benefits in my justification for compatriot partiality. First, I do not offer a blanket justification for all forms of compatriot partiality. Partiality between members of oppressed groups is only a temporary effective measure designed to level an unlevel playing field. Second, because history attests that sovereign republics could arise as a collective response to colonial oppression, justifying compatriot partiality on the grounds that I have identified is conducive to the development of sovereignty and even democracy in poor countries, thereby avoiding problems of infringement that many humanitarian poverty alleviation efforts encounter. Finally, my justification for compatriot partiality complies with the implicit cosmopolitan commitment to the realizability of global justice

The Relationship Between Structural and Catalytic Activity of α and γ-Bismuth-Molybdate Catalysts for Partial Oxidation of Propylene to Acrolein

Science.gov (United States)

Fansuri, H.; Pham, G. H.; Wibawanta, S.; Zhang, D. K.; French, David

Bismuth-molybdate catalysts are known to be effective for catalytic partial oxidation of propylene to acrolein. Their properties and the kinetics and reaction mechanisms for acrolein production have been extensively studied, especially in their basic forms, such as α, β, and γ-bismuth-molybdate. Although the reaction mechanisms have been reported widely in the literature, a general agreement has not been reached, especially from a catalyst-structure point of view. The present contribution reports an effort to understand the structural changes of α and γ-bismuth-molybdate catalysts at varying temperatures as examined using high temperature XRD and to relate the catalyst performance (activity and selectivity) for propylene partial oxidation to acrolein. The XRD analysis was performed at temperature between 250 and 450°C in ambient atmosphere and the Rietveld refinement method was used to extract unit cell parameters. The results showed a distinct similarity between the shapes of the thermal expansion of the catalysts and their activity and selectivity curves, indicating a significant role that the catalyst interatomic structure plays in the overall reaction mechanism.

Extended Catalyst Longevity Via Supercritical Isobutane Regeneration of a Partially Deactivated USY Alkylation Catalyst

Energy Technology Data Exchange (ETDEWEB)

Daniel M. Ginosar; David N. Thompson; Kyle C. Burch; David J. Zalewski

2005-05-01

Off-line, in situ activity recovery of a partially deactivated USY zeolite catalyst used for isobutane/butene alkylation was examined in a continuous-flow reaction system employing supercritical isobutane. Catalyst samples were deactivated in a controlled manner by running them to either to a fixed butene conversion level of 95% or a fixed time on stream of three hours, and then exposing the catalyst to supercritical isobutane to restore activity. Activity recovery was determined by comparing alkylation activity before and after the regeneration step. Both single and multiple regenerations were performed. Use of a 95% butene conversion level criterion to terminate the reaction step afforded 86% activity recovery for a single regeneration and provided nine sequential reaction steps for the multiple regeneration studies. Employing a fixed 3 h time on stream criterion resulted in nearly complete activity recovery for a single regeneration, and 24 reaction steps were demonstrated in sequence for the multiple regeneration process, producing only minor product yield declines per step. This resulted in a 12-fold increase in catalyst longevity versus unregenerated catalyst.

Essays on partial retirement

NARCIS (Netherlands)

Kantarci, T.

2012-01-01

The five essays in this dissertation address a range of topics in the micro-economic literature on partial retirement. The focus is on the labor market behavior of older age groups. The essays examine the economic and non-economic determinants of partial retirement behavior, the effect of partial

The study of the (n,α) and (n,γα) reactions on 143Nd

International Nuclear Information System (INIS)

Aldea, L.; Kardon, B.; Schult, O.W.B.; Seyfarth, H.; Wuest, N.

1977-01-01

Partial cross sections have been measured for the 143 Nd(nsub(th),α) 140 Ce reaction and also for the two-step process 143 Nd(nsub(th),γα) 140 Ce. The results of the present work confirm previous data, but due to lower background, better statistics and resolution improved precision has been obtained. The double-humped structure in the observed (n,γα) spectrum can still be explained through the Porter-Thomas fluctuations of the reduced partial γ and α widths. (orig.) [de

Determination of the partial pressure of thallium in high-pressure lamp arcs: A comparative study

International Nuclear Information System (INIS)

Karabourniotis, D.; Couris, S.; Damelincourt, J.J.; Aubes, M.

1986-01-01

The partial pressure of thallium in high-pressure Hg-TlI discharges with different mercury, thallium, and electron pressures has been measured by using the optically thin line Tl 655 nm and the self-reversed line Tl 535 nm. The partial pressure of the arc axis has been measured from the line Tl 655nm. The effective partial pressure has been measured from the self-reversed line Tl 535 nm on the basis of the multiparameter method, and it has been calculated from the known axis pressure of thallium and the calculation of its radial variation by taking into account the chemical reactions. The experimental results confirm the dispersion character of the blue wing of the line Tl 535 nm. The systematic difference obtained between the measured and calculated effective pressure, particularly at the moment of minimum electron density, may be interpreted by deviations from the local thermodynamic equilibrium (LTE) caused by overpopulation of the upper level of the line Tl 535 nm

Phase behavior and reactive transport of partial melt in heterogeneous mantle model

Science.gov (United States)

Jordan, J.; Hesse, M. A.

2013-12-01

The reactive transport of partial melt is the key process that leads to the chemical and physical differentiation of terrestrial planets and smaller celestial bodies. The essential role of the lithological heterogeneities during partial melting of the mantle is increasingly recognized. How far can enriched melts propagate while interacting with the ambient mantle? Can the melt flow emanating from a fertile heterogeneity be localized through a reactive infiltration feedback in a model without exogenous factors or contrived initial conditions? A full understanding of the role of heterogeneities requires reactive melt transport models that account for the phase behavior of major elements. Previous work on reactive transport in the mantle focuses on trace element partitioning; we present the first nonlinear chromatographic analysis of reactive melt transport in systems with binary solid solution. Our analysis shows that reactive melt transport in systems with binary solid solution leads to the formation of two separate reaction fronts: a slow melting/freezing front along which enthalpy change is dominant and a fast dissolution/precipitation front along which compositional changes are dominated by an ion-exchange process over enthalpy change. An intermediate state forms between these two fronts with a bulk-rock composition and enthalpy that are not necessarily bounded by the bulk-rock composition and enthalpy of either the enriched heterogeneity or the depleted ambient mantle. The formation of this intermediate state makes it difficult to anticipate the porosity changes and hence the stability of reaction fronts. Therefore, we develop a graphical representation for the solution that allows identification of the intermediate state by inspection, for all possible bulk-rock compositions and enthalpies of the heterogeneity and the ambient mantle. We apply the analysis to the partial melting of an enriched heterogeneity. This leads to the formation of moving precipitation

Vadose zone drilling at the NTS

International Nuclear Information System (INIS)

Efurd, D.W.

1994-01-01

The Yucca Mountain Project has an opportunity to evaluate possible mobilization and transport of radioactive materials away from the storage horizon in the proposed repository. One scenario by which such transport could occur involves water leaving the storage area and carrying radioactive particulates of colloidal size. The colloids could move along the gas-liquid interface in partially filled fractures within the vadose zone. It should be possible to check the reality of this proposed scenario by examining ''anthropogenic analogs'' of the repository. These are sites of nuclear tests conducted in unsaturated tuff at the Nevada Test Site (NTS). We propose to drill under one or more such sites to determine if radionuclides have moved from their original confinement in the puddle- glass at the bottom of the cavity. This document examines the characteristics of an ideal test site for such a study, suggests several possible locations that have some of the desired characteristics, and recommends one of these sites for the proposed drilling

Tension stiffening in partially prestressed concrete flexural members

International Nuclear Information System (INIS)

Oukaili, K. N.

2000-01-01

Concrete tensile strength is not being zero, cracking does not extend to the neutral axis as assumed in standard cracked section analysis. In addition, un cracked concrete, which exists above the crack tip in the tension zone, contributes to the stiffness of the member. This paper discusses the influence of concrete tensile stress below the neut ural axis position at the cracked section on the tension stiffening phenomenon and deflection of progressively cracking partially prestressed concrete flexural members. The computation of the neutral axis location, which takes into consideration the effect of concrete in tension, can be achieved by solving iteratively tow simultaneous equation derived from forces and moments equilibrium, strain compatibility and linear stress - strain relationship in concrete across the section depth. Once the section depth after cracking is known, it can be used to calculate the effective moment of inertia for deflection analysis. (author). 13 refs., 3 figs., 1 table

Effects of solid/liquid phase fractionation on pH and aqueous species molality in subduction zone fluids

Science.gov (United States)

Zhong, X.; Galvez, M. E.

2017-12-01

Metamorphic fluids are a crucial ingredient of geodynamic evolution, i.e. heat transfer, rock mechanics and metamorphic/metasomatic reactions. During crustal evolution at elevated P and T, rock forming components can be effectively fractionated from the reactive rock system by at least two processes: 1. extraction from porous rocks by liquid phases such as solute-bearing (e.g. Na+, Mg2+) aqueous fluids or partial melts. 2. isolation from effective bulk rock composition due to slow intragranular diffusion in high-P refractory phases such as garnet. The effect of phase fractionation (garnet, partial melt and aqueous species) on fluid - rock composition and properties remain unclear, mainly due to a high demand in quantitative computations of the thermodynamic interactions between rocks and fluids over a wide P-T range. To investigate this problem, we build our work on an approach initially introduced by Galvez et al., (2015) with new functionalities added in a MATLAB code (Rubisco). The fluxes of fractionated components in fluid, melt and garnet are monitored along a typical prograde P-T path for a model crustal pelite. Some preliminary results suggest a marginal effect of fractionated aqueous species on fluid and rock properties (e.g. pH, composition), but the corresponding fluxes are significant in the context of mantle wedge metasomatism. Our work provides insight into the role of high-P phase fractionation on mass redistribution between the surface and deep Earth in subduction zones. Existing limitations relevant to our liquid/mineral speciation/fractionation model will be discussed as well. ReferencesGalvez, M.E., Manning, C.E., Connolly, J.A.D., Rumble, D., 2015. The solubility of rocks in metamorphic fluids: A model for rock-dominated conditions to upper mantle pressure and temperature. Earth Planet. Sci. Lett. 430, 486-498.

33 CFR 165.169 - Safety and Security Zones: New York Marine Inspection Zone and Captain of the Port Zone.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety and Security Zones: New... Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY... Areas First Coast Guard District § 165.169 Safety and Security Zones: New York Marine Inspection Zone...

Hydrogen isotope exchange reaction rates in tritium, hydrogen and deuterium mixed gases

International Nuclear Information System (INIS)

Uda, Tatsuhiko

1992-01-01

Hydrogen isotope exchange reaction rates in H 2 +T 2 , D 2 +T 2 and H 2 +D 2 +T 2 mixed gases, as induced by tritium decay and beta radiation, were experimentally measured by laser Raman spectrometry. Initially a glass cell was filled with T 2 gas to a pressure of 30-40 kPa, and an equivalent partial pressure of H 2 and/or D 2 was added. The first-order hydrogen isotope exchange reaction rates were 5.54x10 -2 h -1 for H 2 +T 2 mixed gas and 4.76x10 -2 h -1 for D 2 +T 2 . The actual HT producing rate was nearly equivalent to the rate of DT, but the reverse reaction rate of HT was faster than that of DT. The exchange reaction rates between H, D and T showed the isotope effect, HD>HT>DT. The hydrogen isotope exchange reaction rates observed were about twenty times larger than ion formation rates by beta radiation. This result suggests that a free radical chain reaction in hydrogen isotopes is occurring. (orig.)

Experimental R-curve behavior in partially stabilized zirconia using moiracute e interferometry

International Nuclear Information System (INIS)

Perry, K.E.; Okada, H.; Atluri, S.N.

1993-01-01

Moiracute e interferometry is employed to study toughening in partially stabilized zirconia (PSZ). Energy to fracture as a function of crack growth curves (R-curves) is derived from mode I compliance calculations and from near tip fitting of the moiracute e fringes. The effect of the tetragonal to monoclinic phase transformation in the zirconia is found by comparing the bulk compliance R-curves to the locally derived moiracute e R-curve. Localized strain field plots are produced from the moiracute e data for the PSZ zirconia. The observed transformation zone height compares favorably with that predicted by Okada et al. in a companion paper, as does the qualitative nature of the R-curve with predictions by Stump and Budiansky

Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

International Nuclear Information System (INIS)

Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang

2003-12-01

The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

Energy Technology Data Exchange (ETDEWEB)

Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang [Univ. Da Coruna (Spain)

2003-12-01

The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

Driving performance at lateral system limits during partially automated driving.

Science.gov (United States)

Naujoks, Frederik; Purucker, Christian; Wiedemann, Katharina; Neukum, Alexandra; Wolter, Stefan; Steiger, Reid

2017-11-01

This study investigated driver performance during system limits of partially automated driving. Using a motion-based driving simulator, drivers encountered different situations in which a partially automated vehicle could no longer safely keep the lateral guidance. Drivers were distracted by a non-driving related task on a touch display or driving without an additional secondary task. While driving in partially automated mode drivers could either take their hands off the steering wheel for only a short period of time (10s, so-called 'Hands-on' variant) or for an extended period of time (120s, so-called 'Hands-off' variant). When the system limit was reached (e.g., when entering a work zone with temporary lines), the lateral vehicle control by the automation was suddenly discontinued and a take-over request was issued to the drivers. Regardless of the hands-off interval and the availability of a secondary task, all drivers managed the transition to manual driving safely. No lane exceedances were observed and the situations were rated as 'harmless' by the drivers. The lack of difference between the hands-off intervals can be partly attributed to the fact that most of the drivers kept contact to the steering wheel, even in the hands-off condition. Although all drivers were able to control the system limits, most of them could not explain why exactly the take-over request was issued. The average helpfulness of the take-over request was rated on an intermediate level. Consequently, providing drivers with information about the reason for a system limit can be recommended. Copyright © 2017 Elsevier Ltd. All rights reserved.

33 CFR 165.814 - Security Zones; Captain of the Port Houston-Galveston Zone.

Science.gov (United States)

2010-07-01

... Port Houston-Galveston Zone. 165.814 Section 165.814 Navigation and Navigable Waters COAST GUARD... § 165.814 Security Zones; Captain of the Port Houston-Galveston Zone. (a) Location. The following areas are designated as security zones: (1) Houston, Texas. The Houston Ship Channel and all associated...

Nitrogen fluxes through unsaturated zones in five agricultural settings across the United States

Science.gov (United States)

Green, C.T.; Fisher, L.H.; Bekins, B.A.

2008-01-01

The main physical and chemical controls on nitrogen (N) fluxes between the root zone and the water table were determined for agricultural sites in California, Indiana, Maryland, Nebraska, and Washington from 2004 to 2005. Sites included irrigated and nonirrigated fields; soil textures ranging from clay to sand; crops including corn, soybeans, almonds, and pasture; and unsaturated zone thicknesses ranging from 1 to 22 m. Chemical analyses of water from lysimeters and shallow wells indicate that advective transport of nitrate is the dominant process affecting the flux of N below the root zone. Vertical profiles of (i) nitrogen species, (ii) stable isotopes of nitrogen and oxygen, and (iii) oxygen, N, and argon in unsaturated zone air and correlations between N and other agricultural chemicals indicate that reactions do not greatly affect N concentrations between the root zone and the capillary fringe. As a result, physical factors, such as N application rate, water inputs, and evapotranspiration, control the differences in concentrations among the sites. Concentrations of N in shallow lysimeters exhibit seasonal variation, whereas concentrations in lysimeters deeper than a few meters are relatively stable. Based on concentration and recharge estimates, fluxes of N through the deep unsaturated zone range from 7 to 99 kg ha-1 yr-1. Vertical fluxes of N in ground water are lower due to spatial and historical changes in N inputs. High N fluxes are associated with coarse sediments and high N application rates. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

[Dependence of the pharmacokinetics of captopril on the type of adaptation reactions in the organism].

Science.gov (United States)

Udut, V V; Khazanov, V A; Gurto, R V; Borodulina, E V; Postnikova, Iu E

2007-01-01

The dependence of the pharmacokinetic profiles (PhP) of captopril in the phase of adaptation reactions in the organism has been studied within the framework of randomized, comparative, double cross research of bioeqivalency of captopril (Aspharma Co, Anzhero-Sudzhensk) and capoten (Bristol Myers Squibb Co.; official Russian producer, Akrikhin KhimFarmKombinat). It is established that the maximum bioaccessibility and high concentration of captopril in the blood plasma is determined on the background of physiologically optimum reactions of training and in the zone of quiet activation. These characteristics decrease during the reactions of general adaptation syndrome according to the type of increased activation and reactivation.

Nucleon charge exchange reaction and antiproton elastic scattering at intermediate energies

International Nuclear Information System (INIS)

Kronenfeld, J.

1985-02-01

This work treats the medium energy nuclear (p,n) charge exchange reaction to analog states and the low energy elastic scattering of antiprotons and investigates the central aspects of a microscopic theory based on multiple-scattering series which are pertinent to these reactions. A two-step term of the Distorted Wave Impulse Approximation (DWIA) in treating the (p,n) reaction, was included. For the very absorptive p-bar interaction with nuclei we conjecture that a partial infinite summation, constituing a renormalization of the single scattering term of the optical potential series provides the dominant feature of this interaction. In this work the excitation of analog states is calculated and it was found that the (p,n) reaction is described fairly well by the DWIA. In the first part of the work the (p,n) reaction in the energy range 100-200 MeV was treated. The DWIA calculations were based on eikonalization. In the second part of the work the p-barA interaction with the selfconsistent scheme mentioned above, for scattering energies 30-120 MeV, was examined. (author)

Study of the reaction {gamma}p {yields} p{pi}{sup 0}{eta}

Energy Technology Data Exchange (ETDEWEB)

Horn, I.; Bartholomy, O.; Beck, R.; Ehmanns, A.; Ernst, J.; Fabry, I.; Fuchs, M.; Funke, C.; Gutz, E.; Junkersfeld, J.; Kalinowsky, H.; Klempt, E.; Lotz, J.; Pee, H. van; Schmidt, C.; Szczepanek, T.; Thoma, U.; Walther, D.; Weinheimer, C. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Anisovich, A.V.; Nikonov, V.A.; Sarantsev, A.V. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Anton, G.; Bogendoerfer, R.; Foesel, A.; Hoessl, J.; Suft, G. [Universitaet Erlangen, Physikalisches Institut, Erlangen (Germany); Bantes, R.; Gothe, R.; Hoeffgen, S.; Klein, F.; Konrad, M.; Langheinrich, J.; Menze, D.; Ostrick, M.; Schmieden, H.; Schoch, B. [Universitaet Bonn, Physikalisches Institut, Bonn (Germany); Beloglazov, Y.; Gridnev, A.; Lopatin, I.; Novinski, D.; Sumachev, V. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Castelijns, R.; Loehner, H. [Kernfysisch Versneller Instituut, Groningen (Netherlands); Crede, V. [Florida State University, Department of Physics, Tallahassee, FL (United States); Flemming, H.; Koch, H.; Kopf, B.; Matthaey, H. [Universitaet Bochum, Institut fuer Experimentalphysik I, Bochum (Germany); Krusche, B. [Universitaet Basel, Institut fuer Physik, Basel (Switzerland); Messchendorp, J.; Metag, V. [Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany)

2008-11-15

The reaction {gamma}p {yields} p{pi}{sup 0}{eta} has been studied with the CBELSA detector at the tagged photon beam of the Bonn electron stretcher facility. The reaction shows contributions from {delta}{sup +}(1232){eta}, N(1535){sup +}{pi}{sup 0} and pa{sub 0}(980) as intermediate states. A partial-wave analysis suggests that the reaction proceeds via formation of six {delta} -resonances, {delta}(1600)P{sub 33}, {delta}(1920)P{sub 33}, {delta}(1700)D{sub 33}, {delta}(1940)D{sub 33}, {delta}(1905)F{sub 35}, {delta}(2360)D{sub 33}, and two nucleon resonances N(1880)P{sub 11} and N(2200)P{sub 13}, for which pole positions and decay branching ratios are given. (orig.)

Partial-wave analysis of π-π0π0 events at 18 GeV/c

International Nuclear Information System (INIS)

Brown, D.S.

1998-01-01

A partial-wave analysis has been performed on 170 K π - π 0 π 0 events produced in the reaction π - p→pπ - π 0 π 0 , and the results of the mass-independent fits are presented. The objective was to confirm the existence of the π(1800) and the exotic J PC =1 -+ object, reported by VES. copyright 1998 American Institute of Physics

The role of chemical processes and brittle deformation during shear zone formation and its potential geophysical implications

Science.gov (United States)

Goncalves, Philippe; Leydier, Thomas; Mahan, Kevin; Albaric, Julie; Trap, Pierre; Marquer, Didier

2017-04-01

Ductile shear zones in the middle and lower continental crust are the locus of interactions between mechanical and chemical processes. Chemical processes encompass metamorphic reactions, fluid-rock interactions, fluid flow and chemical mass-transfer. Studying these processes at the grain scale, and even the atom scale, on exposed inactive shear zones can give insights into large-scale geodynamics phenomena (e.g. crustal growth and mountain building through the reconstruction of P-T-t-D-Ɛ evolutionary paths. However, other major issues in earth sciences can be tackled through these studies as well. For instance, the mechanism of fluid flow and mass transfer in the deep crust where permeability should be small and transient is still largely debated. Studying exhumed inactive shear zones can also help to interpret several new geophysical observations like (1) the origin of tremor and very low frequency earthquakes observed in the ductile middle and lower crust, (2) mechanisms for generating slow slip events and (3) the physical origin of puzzling crustal anisotropy observed in major active crustal shear zones. In this contribution, we present a collection of data (deformation, petrology, geochemistry, microtexture) obtained on various shear zones from the Alps that were active within the viscous regime (T > 450°C). Our observations show that the development of a shear zone, from its nucleation to its growth and propagation, is not only governed by ductile deformation coeval with reactions but also involves brittle deformation. Although brittle deformation is a very short-lived phenomenon, our petrological and textural observations show that brittle failure is also associated with fluid flow, mass transfer, metasomatic reactions and recrystallization. We speculate that the fluids and the associated mineralogical changes involved during this brittle failure in the ductile crust might play a role in earthquake / tremor triggering below the brittle - ductile transition

Multi-Temperature Zone, Droplet-based Microreactor for Increased Temperature Control in Nanoparticle Synthesis

KAUST Repository

Erdem, E. Yegân

2013-12-12

Microreactors are an emerging technology for the controlled synthesis of nanoparticles. The Multi-Temperature zone Microreactor (MTM) described in this work utilizes thermally isolated heated and cooled regions for the purpose of separating nucleation and growth processes as well as to provide a platform for a systematic study on the effect of reaction conditions on nanoparticle synthesis. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantitative in situ monitoring of an elevated temperature reaction using a water-cooled mid-infrared fiber-optic probe.

Science.gov (United States)

Maclaurin, P; Crabb, N C; Wells, I; Worsfold, P J; Coombs, D

1996-04-01

A novel water-cooled mid-infrared fiber-optic probe is described which is heatable to 230 °C. The probe has chalcogenide fibers and a ZnSe internal reflection element and is compact and fully flexible, allowing access to a wide range of standard laboratory reaction vessels and fume cupboard arrangements. Performance is demonstrated via the in situ analysis of an acid-catalyzed esterification reaction in toluene at 110 °C, and the results are compared with those from a conventional extractive sampling loop flow cell arrangement. Particular emphasis is given to the quantitative interpretation of the spectroscopic data, using gas chromatographic reference data. Calibration data are presented for univariate and partial least squares models, with an emphasis on procedures for improving the quality of interpreparation calibration and prediction through the use of focused reference analysis regimes. Subset univariate procedures are presented that yield relative errors of spectroscopy combined with bias correction partial least squares procedures for the efficient in situ quantitative analysis of laboratory scale reactions.

CFD modeling of combustion processes using KIVA3V Code with partially stirred reactor model for turbulence-combustion interactions

International Nuclear Information System (INIS)

Jarnicki, R.; Sobiesiak, A.

2002-01-01

In order to solve the averaged conservation equations for turbulent reacting flow one is faced with a task of specifying the averaged chemical reaction rate. This is due to turbulence influence on the mean reaction rates that appear in the species concentration Reynolds-averaged equation. In order to investigate the Partially Stirred Reactor (PaSR) combustion model capabilities, a CFD modeling using KIVA3V Code with the PaSR model of two very different combustion processes, was performed. Experimental results were compared with modeling

Transport and degradation of perchlorate in deep vadose zone: implications from direct observations during bioremediation treatment

Science.gov (United States)

Dahan, Ofer; Katz, Idan; Avishai, Lior; Ronen, Zeev

2017-08-01

An in situ bioremediation experiment of a deep vadose zone ( ˜ 40 m) contaminated with a high concentration of perchlorate (> 25 000 mg L-1) was conducted through a full-scale field operation. Favourable environmental conditions for microbiological reduction of perchlorate were sought by infiltrating an electron donor-enriched water solution using drip irrigation underlying an airtight sealing liner. A vadose zone monitoring system (VMS) was used for real-time tracking of the percolation process, the penetration depth of dissolved organic carbon (DOC), and the variation in perchlorate concentration across the entire soil depth. The experimental conditions for each infiltration event were adjusted according to insight gained from data obtained by the VMS in previous stages. Continuous monitoring of the vadose zone indicated that in the top 13 m of the cross section, perchlorate concentration is dramatically reduced from thousands of milligrams per litre to near-detection limits with a concurrent increase in chloride concentration. Nevertheless, in the deeper parts of the vadose zone (< 17 m), perchlorate concentration increased, suggesting its mobilization down through the cross section. Breakthrough of DOC and bromide at different depths across the unsaturated zone showed limited migration capacity of biologically consumable carbon and energy sources due to their enhanced biodegradation in the upper soil layers. Nevertheless, the increased DOC concentration with concurrent reduction in perchlorate and increase in the chloride-to-perchlorate ratio in the top 13 m indicate partial degradation of perchlorate in this zone. There was no evidence of improved degradation conditions in the deeper parts where the initial concentrations of perchlorate were significantly higher.

Modeling and optimization aspects of radiation induced grafting of 4-vinylpyridene onto partially fluorinated films

International Nuclear Information System (INIS)

Nasef, Mohamed Mahmoud; Ahmad Ali, Amgad; Saidi, Hamdani; Ahmad, Arshad

2014-01-01

Modeling and optimization aspects of radiation induced grafting (RIG) of 4-vinylpyridine (4-VP) onto partially fluorinated polymers such as poly(ethylene-co-tetrafluoroethene) (ETFE) and poly(vinylidene fluoride) (PVDF) films were comparatively investigated using response surface method (RSM). The effects of independent parameters: absorbed dose, monomer concentration, grafting time and reaction temperature on the response, grafting yield (GY) were correlated through two quadratic models. The results of this work confirm that RSM is a reliable tool not only for optimization of the reaction parameters and prediction of GY in RIG processes, but also for the reduction of the number of the experiments, monomer consumption and absorbed dose leading to an improvement of the overall reaction cost. - Highlights: • Comparative study of radiation induced grafting of 4-VP onto PVDF and ETFE films. • Optimization of reaction parameters for both grafting systems was made using RSM. • Single factor design for both grafting systems was used as a reference. • Two quadratic regression models were developed for prediction of grafting yield. • RSM is an effective tool for handling grafting reactions under different conditions

Gas phase reactions of nitrogen oxides with olefins

Energy Technology Data Exchange (ETDEWEB)

Altshuller, A P; Cohen, I

1961-01-01

The nature of the condensation products formed in the gas phase reactions of nitrogen dioxide and nitric oxide with pentene-1, 2-methylbutene-2, and 2-methylbutadiene-1,3 was investigated. The reactants were combined at partial pressures in the range of 0.1 to 2.5 mm with the total pressure at one atmosphere. The products were determined by infrared and ultraviolet spectroscopy and colorimetry. The condensates included primary and secondary nitro compounds and alkyl nitrates. Strong hydroxyl and single bond carbon to oxygen stretching vibrations indicate the presence of either nitroalcohols or simple aliphatic alcohols formed through oxidation reactions. Carbonyl stretching frequencies observable in some of the reactions support the conclusion that a portion of the reactants disappear by oxidation rather than by nitration processes. The available results do not indicate the presence of appreciable amounts of tert.-nitro compounds, conjugated nitro-olefins, or gem-dinitro-alkanes. The reactivities of the olefins with the nitrogen oxides are in the decreasing order: 2-methyl-butadiene-1,3, 2-methylbutene-2, pentene-1. 20 references.

Radiation recall secondary to adjuvant docetaxel after balloon-catheter based accelerated partial breast irradiation

International Nuclear Information System (INIS)

Wong, Nathan W.; Wong, William W.; Karlin, Nina J.; Gray, Richard J.

2010-01-01

For early stage breast cancer, wide local excision and post-operative whole breast irradiation is a standard treatment. If adjuvant chemotherapy is recommended, radiation is usually given after completion of chemotherapy. In recent years, accelerated partial breast irradiation (APBI) with balloon-cathetered based brachytherapy has become an option for selected patients. For these patients, adjuvant chemotherapy would have to be administered after radiation. The sequence of treatment with radiation followed by chemotherapy results in increased risk of radiation recall reaction (RRD) in these patients. Docetaxel is becoming a more commonly used drug as adjuvant treatment for breast cancer. Here we report a case of docetaxel induced RRD after APBI with balloon-cathetered based brachytherapy. Such reaction would have an adverse impact on the cosmetic outcome and quality of life of the patient. For patients who develop an intense skin reaction after the administration of docetaxel following APBI, RRD should be considered in the differential diagnosis.

The Sorong Fault Zone, Indonesia: Mapping a Fault Zone Offshore

Science.gov (United States)

Melia, S.; Hall, R.

2017-12-01

The Sorong Fault Zone is a left-lateral strike-slip fault zone in eastern Indonesia, extending westwards from the Bird's Head peninsula of West Papua towards Sulawesi. It is the result of interactions between the Pacific, Caroline, Philippine Sea, and Australian Plates and much of it is offshore. Previous research on the fault zone has been limited by the low resolution of available data offshore, leading to debates over the extent, location, and timing of movements, and the tectonic evolution of eastern Indonesia. Different studies have shown it north of the Sula Islands, truncated south of Halmahera, continuing to Sulawesi, or splaying into a horsetail fan of smaller faults. Recently acquired high resolution multibeam bathymetry of the seafloor (with a resolution of 15-25 meters), and 2D seismic lines, provide the opportunity to trace the fault offshore. The position of different strands can be identified. On land, SRTM topography shows that in the northern Bird's Head the fault zone is characterised by closely spaced E-W trending faults. NW of the Bird's Head offshore there is a fold and thrust belt which terminates some strands. To the west of the Bird's Head offshore the fault zone diverges into multiple strands trending ENE-WSW. Regions of Riedel shearing are evident west of the Bird's Head, indicating sinistral strike-slip motion. Further west, the ENE-WSW trending faults turn to an E-W trend and there are at least three fault zones situated immediately south of Halmahera, north of the Sula Islands, and between the islands of Sanana and Mangole where the fault system terminates in horsetail strands. South of the Sula islands some former normal faults at the continent-ocean boundary with the North Banda Sea are being reactivated as strike-slip faults. The fault zone does not currently reach Sulawesi. The new fault map differs from previous interpretations concerning the location, age and significance of different parts of the Sorong Fault Zone. Kinematic

Investigation of (n,γ) reactions in fissionable fluids in a hybrid reactor system

Energy Technology Data Exchange (ETDEWEB)

Guenay, Mehtap [Inoenue Univ., Malatya (Turkey). Physics Dept.

2014-06-15

In this study, the effect of (n,γ) reactions in spent fuel-grade (SFG)-PuO{sub 2}, UO{sub 2}, NpO{sub 2} and UCO contents was investigated in a designed hybrid reactor system. In this system, the molten salt-heavy metal mixtures 93 - 85 % Li{sub 20}Sn{sub 80} + 5 % SFG-PuO{sub 2} and 2 - 10 % UO{sub 2}, 93 - 85 % Li{sub 20}Sn{sub 80} + 5 % SFG-PuO{sub 2} and 2 - 10 % NpO{sub 2}, 93 - 85 % Li{sub 20}Sn{sub 80} + 5 % SFG-PuO{sub 2} and 2 - 10 % UCO were used as fluids. Beryllium (Be) is used as neutron multiplier by (n,2n) reactions. Thence, a Be zone with a width of 3 cm was used in order to contribute on fissile fuel breeding between the liquid first wall and blanket. (n,γ) reactions were calculated in the liquid first wall, blanket and shield zones, which SFG-PuO{sub 2}, UO{sub 2}, NpO{sub 2} and UCO contents. 9Cr2WVTa ferritic steel with the width of 4 cm was used as the structural material. Three-dimensional nucleonic calculations were performed using the most recent version MCNPX-2.7.0 the Monte Carlo code and nuclear data library ENDF/B-VII.0. (orig.)

A two-dimensional time domain near zone to far zone transformation

Science.gov (United States)

Luebbers, Raymond J.; Ryan, Deirdre; Beggs, John H.; Kunz, Karl S.

1991-01-01

In a previous paper, a time domain transformation useful for extrapolating 3-D near zone finite difference time domain (FDTD) results to the far zone was presented. In this paper, the corresponding 2-D transform is outlined. While the 3-D transformation produced a physically observable far zone time domain field, this is not convenient to do directly in 2-D, since a convolution would be required. However, a representative 2-D far zone time domain result can be obtained directly. This result can then be transformed to the frequency domain using a Fast Fourier Transform, corrected with a simple multiplicative factor, and used, for example, to calculate the complex wideband scattering width of a target. If an actual time domain far zone result is required it can be obtained by inverse Fourier transform of the final frequency domain result.

Non-invasive estimation of dissipation from non-equilibrium fluctuations in chemical reactions.

Science.gov (United States)

Muy, S; Kundu, A; Lacoste, D

2013-09-28

We show how to extract an estimate of the entropy production from a sufficiently long time series of stationary fluctuations of chemical reactions. This method, which is based on recent work on fluctuation theorems, is direct, non-invasive, does not require any knowledge about the underlying dynamics and is applicable even when only partial information is available. We apply it to simple stochastic models of chemical reactions involving a finite number of states, and for this case, we study how the estimate of dissipation is affected by the degree of coarse-graining present in the input data.

Partial Portal Vein Arterialization Attenuates Acute Bile Duct Injury Induced by Hepatic Dearterialization in a Rat Model.

Science.gov (United States)

Jiang, Jun; Wei, Jishu; Wu, Junli; Gao, Wentao; Li, Qiang; Jiang, Kuirong; Miao, Yi

2016-01-01

Hepatic infarcts or abscesses occur after hepatic artery interruption. We explored the mechanisms of hepatic deprivation-induced acute liver injury and determine whether partial portal vein arterialization attenuated this injury in rats. Male Sprague-Dawley rats underwent either complete hepatic arterial deprivation or partial portal vein arterialization, or both. Hepatic ischemia was evaluated using biochemical analysis, light microscopy, and transmission electron microscopy. Hepatic ATP levels, the expression of hypoxia- and inflammation-associated genes and proteins, and the expression of bile transporter genes were assessed. Complete dearterialization of the liver induced acute liver injury, as evidenced by the histological changes, significantly increased serum biochemical markers, decreased ATP content, increased expression of hypoxia- and inflammation-associated genes and proteins, and decreased expression of bile transporter genes. These detrimental changes were extenuated but not fully reversed by partial portal vein arterialization, which also attenuated ductular reaction and fibrosis in completely dearterialized rat livers. Collectively, complete hepatic deprivation causes severe liver injury, including bile infarcts and biloma formation. Partial portal vein arterialization seems to protect against acute ischemia-hypoxia-induced liver injury.

Partial Portal Vein Arterialization Attenuates Acute Bile Duct Injury Induced by Hepatic Dearterialization in a Rat Model

Directory of Open Access Journals (Sweden)

Jun Jiang

2016-01-01

Full Text Available Hepatic infarcts or abscesses occur after hepatic artery interruption. We explored the mechanisms of hepatic deprivation-induced acute liver injury and determine whether partial portal vein arterialization attenuated this injury in rats. Male Sprague-Dawley rats underwent either complete hepatic arterial deprivation or partial portal vein arterialization, or both. Hepatic ischemia was evaluated using biochemical analysis, light microscopy, and transmission electron microscopy. Hepatic ATP levels, the expression of hypoxia- and inflammation-associated genes and proteins, and the expression of bile transporter genes were assessed. Complete dearterialization of the liver induced acute liver injury, as evidenced by the histological changes, significantly increased serum biochemical markers, decreased ATP content, increased expression of hypoxia- and inflammation-associated genes and proteins, and decreased expression of bile transporter genes. These detrimental changes were extenuated but not fully reversed by partial portal vein arterialization, which also attenuated ductular reaction and fibrosis in completely dearterialized rat livers. Collectively, complete hepatic deprivation causes severe liver injury, including bile infarcts and biloma formation. Partial portal vein arterialization seems to protect against acute ischemia-hypoxia-induced liver injury.

Root zone effects on tracer migration in arid zones

International Nuclear Information System (INIS)

Tyler, S.W.; Walker, G.R.

1994-01-01

The study of groundwater recharge and soil water movement in arid regions has received increased attention in the search for safe disposal sites for hazardous wastes. In passing through the upper 1 to 2 m of most soil profiles, tracers indicative of recharge such as Cl, 2 H, 18 O, Br, 3 H, and 56 Cl are subjected to a wide range of processes not encountered deeper in the profile. This transition zone, where water enters as precipitation and leaves as recharge, is often ignored when environmental tracers are used to estimate deep soil water flux and recharge, yet its effect may be profound. In this work, we reexamine the processes of root extraction and its effect on the velocity and distribution of tracers. Examples are presented for idealized conditions, which show clearly the relation between the root zone processes and the deep drainage or recharge. The results indicate that, when recharge is small and root zone processes are not accounted for, tracer techniques can significantly overestimate recharge until the tracer has moved well below the root zone. By incorporating simple models of root zone processes, a clearer understanding of tracer distributions and a more accurate estimate of recharge can then be made. 11 refs., 9 figs

75 FR 50700 - Quarterly Listings; Safety Zones, Security Zones, Special Local Regulations, and Drawbridge...

Science.gov (United States)

2010-08-17

...] Quarterly Listings; Safety Zones, Security Zones, Special Local Regulations, and Drawbridge Operation... notice lists temporary safety zones, security zones, special local regulations, and drawbridge operation... responsive to the safety and security needs within their jurisdiction; therefore, District Commanders and...

A NEW INTERPRETATION FOR THE GARNET ZONING IN METAPELITIC ROCKS OF THE SILGARÁ FORMATION, SOUTHWESTERN SANTANDER MASSIF, COLOMBIA

Directory of Open Access Journals (Sweden)

Ríos Reyes Carlos Alberto

2008-06-01

Full Text Available A Barrovian sequence of the Silgará Formation at the southwestern Santander Massif, Colombian Andes, contains zoned garnets in which major and trace element zoning correlates with distribution of mineral inclusions, which may indicate that garnet growth rate varied through time and affected both composition and texture ofgarnets, although different garnet producing reactions have also played an important role in the chemical zoning of garent. However, a local metasomatism process associated to the action of late magmatic fluids associated to the emplacement of the Pescadero Pluton (external forcing mechanism would be also considered. In particular, Ca, Mn and Y zoning patterns in some garnets correspond with inclusion-rich vs. inclusion-free zones, althoughthe distribution of inclusions does not correlate with chemical zoning (i.e., the same inclusions are found in Ca-rich and Ca-poor zones of the garnet. There is a similar lack of correlation with accessory phases (apatite, monazite, xenotime, ilmenite or rutile. In a garnet from the garnet-staurolite zone, a high Mn core containsabundant and randomly oriented apatite, monazite and ilmenite inclusions, while a euhedral low Ca mantle zone is inclusion-free and the high Ca / low Mn rim zone contains apatite, monazite and ilmenite aligned parallel to the margins of the garnet. Inclusions in garnet can also represent mineral phases were not completely consumed during garnet growth. Association of garnet zoning trends and patterns with inclusion distribution may help differentiatebetween processes that identically affect major-element zoning but that produced variable textures in the garnet.

Radiant zone heated particulate filter

Science.gov (United States)

Gonze, Eugene V [Pinckney, MI

2011-12-27