Study of proton polarization in charge exchange process on optically oriented sodium atoms

International Nuclear Information System (INIS)

Zelenskij, A.N.; Kokhanovskij, S.A.

1984-01-01

Using high-power adjustable dye lasers for electron spin orientation in a charge-exchange target enables to significantly increase the proton polarization efficiency. A device is described that permits to avoid growth of the polarized proton beam emittance in a charge-exchange process in a strong magnetic field. The devise main feature is the use of an intensive source of neutral hydrogen atoms and the presence of a helium additional charge-exchange target which actualy is a proton ''source''. The helium charge-exchange cell is placed in the same magnetic field of a solenoid where a cell with oriented sodium is placed, a polarized electron being captured by a proton in the latter cell. In this case the beam at the solenoid inlet and outlet is in a neutral state; emittance growth related to the effect of end magnetic fields is not observed. The device after all prouduces polarized protons, their polarization degree is measured and the effect of various factors on polarization degree is studied. The description of the laser source and laser system is given. Measurement results have shown the beam intensity of neutral 7 keV atoms which passed through a polarizer to be 2 mA. The proton current doesn't depend. On the beeld fin the region of chrge exchange for the 8 kGs magnetic field. The degree of sodium polarization was 80% and polarized proton current approximately 70 μA at a temperature of the polarized sodium cell corresponding to the density of sodium vapar approximately 3x10 13 at/cm 2

How Sodium Chloride Salt Inhibits the Formation of CO2 Gas Hydrates.

Science.gov (United States)

Holzammer, Christine; Finckenstein, Agnes; Will, Stefan; Braeuer, Andreas S

2016-03-10

We present an experimental Raman study on how the addition of sodium chloride to CO2-hydrate-forming systems inhibits the hydrate formation thermodynamically. For this purpose, the molar enthalpy of reaction and the molar entropy of reaction for the reaction of weakly hydrogen-bonded water molecules to strongly hydrogen bonded water molecules are determined for different salinities from the Raman spectrum of the water-stretching vibration. Simultaneously, the influence of the salinity on the solubility of CO2 in the liquid water-rich phase right before the start of hydrate formation is analyzed. The results demonstrate that various mechanisms contribute to the inhibition of gas hydrate formation. For the highest salt concentration of 20 wt % investigated, the temperature of gas hydrate formation is lowered by 12 K. For this concentration the molar enthalpy and entropy of reaction become smaller by 50 and 20%, respectively. Concurrently, the solubility of carbon dioxide is reduced by 70%. These results are compared with data in literature for systems of sodium chloride in water (without carbon dioxide).

Economical Aspects of Sodium Borohydride for Hydrogen Storage

International Nuclear Information System (INIS)

Ture, I. Engin; Tabakoglu, F. Oznur; Kurtulus, Gulbahar

2006-01-01

Hydrogen is the best fuel among others, which can minimize the cause to global warming. Turkey has an important location with respect to hydrogen energy applications. Moreover, Turkey has 72.2% of the world's total boron reserves. Sodium borohydride (NaBH 4 ) which can be produced from borax has high hydrogen storage capacity. Hence, it is important for Turkey to lead studies about sodium borohydride to make it one of the most feasible hydrogen storage methods. In this paper an approximate process cost analysis of a NaBH 4 -H 2 system is given, starting with NaBH 4 production till recycling of it. It is found that, the usage of NaBH 4 as hydrogen storage material is relatively an expensive method but after improving reactions and by-product removal in the system and reducing the energy and reactant costs, sodium borohydride is one of the best candidates among hydrogen storage technologies. (authors)

Assessment of flow induced vibration in a sodium-sodium heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Prakash, V. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)], E-mail: prakash@igcar.gov.in; Thirumalai, M.; Prabhakar, R.; Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)

2009-01-15

The 500 MWe Prototype Fast Breeder Reactor (PFBR) is under construction at Kalpakkam. It is a liquid metal sodium cooled pool type fast reactor with all primary components located inside a sodium pool. The heat produced due to fission in the core is transported by primary sodium to the secondary sodium in a sodium to sodium Intermediate Heat Exchanger (IHX), which in turn is transferred to water in the steam generator. PFBR IHX is a shell and tube type heat exchanger with primary sodium on shell side and secondary sodium in the tube side. Since IHX is one of the critical components placed inside the radioactive primary sodium, trouble-free operation of the IHX is very much essential for power plant availability. To validate the design and the adequacy of the support system provided for the IHX, flow induced vibration (FIV) experiments were carried out in a water test loop on a 60 deg. sector model. This paper discusses the flow induced vibration measurements carried out in 60 deg. sector model of IHX, the modeling criteria, the results and conclusion.

Sodium Borohydride/Hydrogen Peroxide Fuel Cells For Space Application

Science.gov (United States)

Valdez, T. I.; Deelo, M. E.; Narayanan, S. R.

2006-01-01

This viewgraph presentation examines Sodium Borohydride and Hydrogen Peroxide Fuel Cells as they are applied to space applications. The topics include: 1) Motivation; 2) The Sodium Borohydride Fuel Cell; 3) Sodium Borohydride Fuel Cell Test Stands; 4) Fuel Cell Comparisons; 5) MEA Performance; 6) Anode Polarization; and 7) Electrode Analysis. The benefits of hydrogen peroxide as an oxidant and benefits of sodium borohydride as a fuel are also addressed.

Comparison of hydrogen isotope exchange reactions between HTO vapor and the sodium salts of o-, m-, and p-aminobenzoic acid

International Nuclear Information System (INIS)

Okada, Minoru; Imaizumi, Hiroshi; Itoh, Tomoko

1991-01-01

Hydrogen isotope exchange reaction between HTO vapor and one of the sodium salts of o-, m-, and p-aminobenzoic acid (solid) was observed at 50 ∼ 80 degC. The acidity (acidity based on kinetic logic) for the materials at each temperature has been obtained with the A''-McKay plots based on the respective data obtained. The followings have been clarified by comparing these acidities (and the acidities obtained previously). 1) The acidity of aromatic amines can be expressed in terms of the acidity based on kinetic logic. 2) The reactivity of aromatic amine is strongly affected by both I-effect and R-effect. 3) It can be deduced that aromatic amines are more reactive than aliphatic amines. (author)

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

Science.gov (United States)

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-07-14

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

Performance Evaluation in Sodium-to-Sodium Heat Exchangers in STELLA-2

International Nuclear Information System (INIS)

Jo, Youngchul; Son, Seok-kwon; Yoon, Jung; Jeong, Jiyoung

2016-01-01

The program aiming at an integral effect test is called STELLA-2, which will be used for synthetic review of the key safety issues of PGSFR. The basic and detailed design phases of the STELLA-2 test facility are underway in accordance with the specific design requirements reflecting the whole design features of PGSFR. Based on the STELLA-2 platform, a simulation of the PGSFR transient will be made to evaluate the plant dynamic behaviors and demonstrate the decay heat removal performance. The multi-dimensional effects coming from a large sodium pool system will be identified as well. Among several components of STELLA-2, there are five different types of model heat exchangers such as IHX, DHX, FHX, AHX, and UHX. Each heat exchanger has different characteristics, and it is very important to verify the heat transfer and pressure drop performance in each heat exchanger. The performance evaluation of the sodium-to-sodium heat exchangers (IHX and DHX) in STELLA-2 is performed using CFD. Also, these results are compared with 1-D heat exchanger design code. The shell/tube outlet temperature and heat transfer rate of the heat exchanger obtained by the CFD is not significantly

Contribution to the study of catalytic hydrogen-deuterium exchange between hydrogen and hydrocarbons

International Nuclear Information System (INIS)

Ravoire, J.

1958-01-01

The hydrogen-deuterium exchange between molecular hydrogen and hydrocarbons over a platinum and charcoal catalyst was studied in a static system. The change in isotopic composition of molecular hydrogen was followed by a thermal conductivity method. Cyclo-pentane and cyclohexane were chosen because of their stability. A reversible inactivation of the catalyst was observed with both hydrocarbons. The reasons for this inactivation are unknown but it was shown that reactivation led to satisfactory reproducibility. A kinetic study was done with cyclohexane in the range 30 to 160 deg. C, and 40 to 360 mm for the pressure of hydrogen, and 10 to 70 mm for the pressure of cyclohexane. The order of the reaction with respect to cyclohexane pressure is always close to zero; the order with respect to that of hydrogen is 0.5 above 100 deg. C. It decreases with increasing temperature and becomes negative (-0.5 at 30 deg. C), characterizing an inhibition by hydrogen. At the same time, the apparent activation energy goes from 6 to 13 kcal/mole. (author) [fr

Thermal performance tests on a sodium-to-sodium heat exchanger

International Nuclear Information System (INIS)

Prahlad, B.; Kale, R.D.; Rajan, K.K.

1990-01-01

Thermal performance of a 3 MW sodium-to-sodium intermediate heat exchanger (IHX) was evaluated under temperature conditions typical of a Fast Breeder Reactor IHX. A regenerative figure of eight loop was used with the heat exchanger at the cross over point, and a 500 kW heat source and an air cooled sink to maintain the desired test conditions. The overall heat transfer coefficient was found to vary from 4.02 to 4.87 kW/m 2 ·K for Peclet numbers varying from 37 to 112.5 on the shell side and 44.4 to 133.5 on the tube side respectively. The Peclet numbers were representative of low turbulent regime in this case. While the overall heat transfer coefficient was found close to predictions using Lubarsky's correlation, it was somewhat lower than that predicted by later correlations of Spukunsky and Borishansky. The reasons for the lower overall heat transfer coefficient have been explained in terms of possible maldistribution of shell side flow in low turbulent regime reducing the effective heat transfer area and increased thermal contact resistance. Based on their findings the authors feel that heat transfer in a sodium-to-sodium heat exchanger at low Peclet numbers is expected to differ from that obtained with large Peclet numbers. (author)

Preparation by ion exchange and structural simulation of a new hydrogen phosphate of sodium zirconium

International Nuclear Information System (INIS)

Contreras R, A.; Fernandez V, S. M.; Ordonez R, E.; Perez A, M.

2008-01-01

It is described the method of synthesis of the τ-Zr P and the obtaining of its sodium form by ion exchange, the simulation of crystalline model and their patterns of X-ray diffraction and comparison of these with other compounds reported in the literature. (Author)

Development of hydrogen storage systems using sodium alanate

Energy Technology Data Exchange (ETDEWEB)

Lozano Martinez, Gustavo Adolfo

2010-12-06

In this work, hydrogen storage systems based on sodium alanate were studied, modelled and optimised, using both experimental and theoretical approaches. The experimental approach covered investigations of the material from mg scale up to kg scale in demonstration test tanks, while the theoretical approach discussed modelling and simulation of the hydrogen sorption process in a hydride bed. Both approaches demonstrated the strong effect of heat transfer on the sorption behaviour of the hydride bed and led to feasible methods to improve and optimise the volumetric and gravimetric capacities of hydrogen storage systems. The applied approaches aimed at an optimal integration of sodium alanate material in practical hydrogen storage systems. First, it was experimentally shown that the size of the hydride bed influences the hydrogen sorption behaviour of the material. This is explained by the different temperature profiles that are developed inside the hydride bed during the sorptions. In addition, in a self-constructed cell it was possible to follow the hydrogen sorptions and the developed temperature profiles within the bed. Moreover, the effective thermal conductivity of the material was estimated in-situ in this cell, given very good agreement with reported values of ex-situ measurements. It was demonstrated that the effective thermal conductivity of the hydride bed can be enhanced by the addition of expanded graphite. This enhancement promotes lower temperature peaks during the sorptions due to faster heat conduction through the bed, which in addition allows faster heat transfer during sorption. Looking towards simulations and further evaluations, empirical kinetic models for both hydrogen absorption and desorption of doped sodium alanate were developed. Based on the results of the model, the optimal theoretical pressure-temperature conditions for hydrogen sorptions were determined. A new approach is proposed for the mass balance of the reactions when implementing

Sodium-sodium intermediate heat exchangers design problems

International Nuclear Information System (INIS)

Chandramohan, R.

1975-01-01

This paper deals briefly with the calculation methods adapted, in working-out the stresses due to fluid pressures (normal as well as transient), weights, piping-reactions, vibration in the tube-bundle and also the thermal stresses during normal and transient conditions, for the mechanical design of intermediate heat-exchanger. The thermal stress evaluation of the tube-sheet is given particular emphasis. A brief outline of the design problems connected with the Na-Na exchangers of large size sodium cooled fast reactor plants is also given. (author)

Sodium Is Not Required for Chloride Efflux via Chloride/Bicarbonate Exchanger from Rat Thymic Lymphocytes

Directory of Open Access Journals (Sweden)

Donatas Stakišaitis

2014-01-01

Full Text Available Sodium-dependent Cl−/HCO3- exchanger acts as a chloride (Cl− efflux in lymphocytes. Its functional characterization had been described when Cl− efflux was measured upon substituting extracellular sodium (Na+ by N-methyl-D-glucamine (NMDG. For Na+ and Cl− substitution, we have used D-mannitol or NMDG. Thymocytes of male Wistar rats aged 7–9 weeks were used and intracellular Cl− was measured by spectrofluorimetry using MQAE dye in bicarbonate buffers. Chloride efflux was measured in a Cl−-free buffer (Cl− substituted with isethionate acid and in Na+ and Cl−-free buffer with D-mannitol or with NMDG. The data have shown that Cl− efflux is mediated in the absence of Na+ in a solution containing D-mannitol and is inhibited by H2DIDS. Mathematical modelling has shown that Cl− efflux mathematical model parameters (relative membrane permeability, relative rate of exchanger transition, and exchanger efficacy were the same in control and in the medium in which Na+ had been substituted by D-mannitol. The net Cl− efflux was completely blocked in the NMDG buffer. The same blockage of Cl− efflux was caused by H2DIDS. The study results allow concluding that Na+ is not required for Cl− efflux via Cl−/HCO3- exchanger. NMDG in buffers cannot be used for substituting Na+ because NMDG inhibits the exchanger.

Sodium vapor charge exchange cell

International Nuclear Information System (INIS)

Hiddleston, H.R.; Fasolo, J.A.; Minette, D.C.; Chrien, R.E.; Frederick, J.A.

1976-01-01

An operational sequential charge-exchange ion source yielding a 50 MeV H - current of approximately 8 mA is planned for use with the Argonne 500 MeV booster synchrotron. We report on the progress for development of a sodium vapor charge-exchange cell as part of that planned effort. Design, fabrication, and operating results to date are presented and discussed. (author)

The reactions of oxygen and hydrogen with liquid sodium

International Nuclear Information System (INIS)

Ullmann, H.

1981-01-01

Results so far available as to the reactions and chemical equilibrium of oxygen and hydrogen with liquid sodium have been analyzed critically. The enthalpy values of the reactions have been discussed and supplemented on the basis of corresponding BORN-HABER cycles. The concentration and temperature functions of the hydrogen equilibrium pressure were deduced from experimental results. In relation to the solubility data the solid phases coexisting with liquid sodium in the ternary system Na-O-H have been discussed. The reaction of oxygen with hydrogen in diluted solution in liquid sodium has been investigated in more detail. Interaction coefficients, and the temperature functions of the free energy of formation and the equilibrium constant have been determined. (orig.)

The determination of hydrogen in sodium by vacuum extraction

International Nuclear Information System (INIS)

Qi Linkun; Wan Gang; Wen Ximeng; Sun Shiping; Jia Yunteng

1993-05-01

A method to determine the hydrogen in sodium is introduced. The sodium sample, which is less than 7 g, is put into a thin iron capsule in argon atmosphere, the capsule is sealed by electron beam welding and heated to 700 degree C in a vacuum system with pressure less than 10 -5 Pa, then the hydrogen released from the vacuum system can be determined. The determining limit by this method is 20 ∼ 150 μg and the standard deviation is 20%. This method uses electron beam welding to replace the argon are welding and combines the off-line sampling with on-line measuring. It is an easier off-line measurement to determine hydrogen in sodium

Hydrogen/deuterium exchange in mass spectrometry.

Science.gov (United States)

Kostyukevich, Yury; Acter, Thamina; Zherebker, Alexander; Ahmed, Arif; Kim, Sunghwan; Nikolaev, Eugene

2018-03-30

The isotopic exchange approach is in use since the first observation of such reactions in 1933 by Lewis. This approach allows the investigation of the pathways of chemical and biochemical reactions, determination of structure, composition, and conformation of molecules. Mass spectrometry has now become one of the most important analytical tools for the monitoring of the isotopic exchange reactions. Investigation of conformational dynamics of proteins, quantitative measurements, obtaining chemical, and structural information about individual compounds of the complex natural mixtures are mainly based on the use of isotope exchange in combination with high resolution mass spectrometry. The most important reaction is the Hydrogen/Deuterium exchange, which is mainly performed in the solution. Recently we have developed the approach allowing performing of the Hydrogen/Deuterium reaction on-line directly in the ionization source under atmospheric pressure. Such approach simplifies the sample preparation and can accelerate the exchange reaction so that certain hydrogens that are considered as non-labile will also participate in the exchange. The use of in-ionization source H/D exchange in modern mass spectrometry for structural elucidation of molecules serves as the basic theme in this review. We will focus on the mechanisms of the isotopic exchange reactions and on the application of in-ESI, in-APCI, and in-APPI source Hydrogen/Deuterium exchange for the investigation of petroleum, natural organic matter, oligosaccharides, and proteins including protein-protein complexes. The simple scenario for adaptation of H/D exchange reactions into mass spectrometric method is also highlighted along with a couple of examples collected from previous studies. © 2018 Wiley Periodicals, Inc.

Separation of hydrogen isotope by hydrogen-water exchange

International Nuclear Information System (INIS)

Isomura, Shohei; Kaetsu, Hayato; Nakane, Ryohei

1979-01-01

The deuterium exchange reaction between gaseous hydrogen and liquid water is studied by use of three kinds of trickle bed exchange columns packed with hydrophobic catalysts supporting platinum. All columns have the effective lengths of 30 cm. They are 17 mm, 30 mm, and 95 mm in diameters, respectively. The separation experiments are carried out by the once-through methods. The separation efficiencies of the columns are evaluated by the parameters such as the height equivalent to a theoretical plate (H. E. T. P.) and the mass transfer co-efficient. It is found that the operating condition of the exchange column is optimum when the superficial hydrogen flow velocity is 0.3 m/sec. (author)

Hydrogen and oxygen isotope exchange reactions over illuminated and nonilluminated TiO2

International Nuclear Information System (INIS)

Sato, S.

1987-01-01

Hydrogen isotope exchange between H 2 , gaseous H 2 O, and the surface hydroxyls of TiO 2 , and oxygen isotope exchange between O 2 , CO 2 , CO, H 2 O vapor, and the hydroxyls over TiO 3 were studied at room temperature in the dark and under illumination. Hydrogen isotope exchange between H 2 O and the hydroxyls occurred rapidly in the dark, but the exchange involving H 2 did not occur at all even under illumination. Oxygen isotope exchange among H 2 O vapor, CO 2 , and the hydroxyls easily took place in the dark, but the exchange involving O 2 required band-gap illumination. Dioxygen isotope equilibration was much faster than the other photoexchange reactions. Although the oxygen exchange between O 2 and illuminated TiO 2 has been considered to involve lattice-oxygen exchange, the present experiments revealed that the hydroxyls of TiO 2 mainly participate in the exchange reaction. The oxygen exchange between O 2 and H 2 O vapor was strongly inhibited by H 2 O vapor itself probably because oxygen adsorption was retarded by adsorbed water. Oxygen in CO was not exchanged with the other substrates under any conditions tested

Study on the exchangeable body sodium in diabetes mellitus

International Nuclear Information System (INIS)

de Chatel, Rudolf; Barna, Istvan; Krasznai, Istvan

1985-01-01

Ten patients with diabetes mellitus, apperently free of any complications of diabetes and of hypertension, had a significantly (p<0.01) increased exchangeable body sodium compared to 10 sex-matched control subjects of comparable age, body weight and height, and blood pressure. Exchangeable sodium correlated significantly (p<0.01) with supine mean blood pressure in the diabetic patients (r=0.822) but not in the control subjects (r=0.276). It is suggested that the early increase of exchangeable body sodium in diabetes mellitus might play a part in the high incidence of hypertension in such patients. (author)

Measurements of hydrogen concentration in liquid sodium by using an inert gas carrier method

International Nuclear Information System (INIS)

Funada, T.; Nihei, I.; Yuhara, S.; Nakasuji, T.

1979-01-01

A technique was developed to measure the hydrogen level in liquid sodium using an inert gas carrier method. Hydrogen was extracted into an inert gas from sodium through a thin nickel membrane in the form of a helically wound tube. The amount of hydrogen in the inert gas was analyzed by gas chromatography. The present method is unique in that it can be used over the wide range of sodium temperatures (150 to 700 0 C) and has no problems associated with vacuum systems. The partial pressure of hydrogen in sodium was determined as a function of cold-trap temperature (T/sub c/). Sieverts' constant (K/sub s/) was determined as a function of sodium temperature (T). From Sieverts' constant, the solubility of hydrogen in sodium is calculated. It was found that other impurities in sodium, such as (O) and (OH), have little effect on the hydrogen pressure in the sodium loop

Dynamic thermal baffle on lower head of FBR sodium-sodium intermediate heat exchanger

International Nuclear Information System (INIS)

Charbonnel, A.; Foussat, C.

1981-01-01

The cover head of the heat exchanger is bathed on the one side by the primary sodium of the 'cold' header of the vessel and on the other side by the secondary sodium which feeds the heat exchange tube bank through the lower tubesheet. In the case of transient or permanent operating conditions at partial ratings, there are large temperature differences between the inner sodium (inlet temperature conditions of secondary sodium) and the outer sodium (mean temperature conditions in the primary sodium outlet port), hence the necessity of designing a thermal baffle which protects the head and its connection to the tubesheet. A 'static' thermal baffle consisting of a thick steel plate enclosing static sodium around the head proves inadequate during transient operating conditions. This is why a 'dynamic' thermal baffle is used whose design is based on the fact that the primary sodium in the lower part of the outlet port is always at a temperature close to that of the secondary sodium in the inlet header and the head. The primary sodium is taken from the bottom of the outlet port by a ring deflector and circulates in an annulus created by a double housing and the head. It flows out through openings in the lower part of the housing. (orig./GL)

Process for exchanging hydrogen isotopes between gaseous hydrogen and water

International Nuclear Information System (INIS)

Hindin, S. G.; Roberts, G. W.

1980-01-01

A process for exchanging isotopes of hydrogen, particularly tritium, between gaseous hydrogen and water is provided whereby gaseous hydrogen depeleted in tritium and liquid or gaseous water containing tritium are reacted in the presence of a metallic catalyst

Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

Energy Technology Data Exchange (ETDEWEB)

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2017-12-19

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

The equilibrium hydrogen pressure-temperature diagram for the liquid sodium-hydrogen-oxygen system

International Nuclear Information System (INIS)

Knights, C.F.; Whittingham, A.C.

1982-01-01

The underlying equilibria in the sodium-hydrogen-oxygen system are presented in the form of a completmentary hydrogen equilibrium pressure-temperature diagram, constructed by using published data and supplemented by experimental measurements of hydrogen equilibrium pressures over condensed phases in the system. Possible applications of the equilibrium pressure-temperature phase diagram limitations regarding its use are outlined

Numerical Analysis of Flow Distribution in a Sodium Chamber of a Finned-tube Sodium-to-Air Heat Exchanger

Energy Technology Data Exchange (ETDEWEB)

Jo, Youngchul; Son, Seokkwon; Kim, Hyungmo; Eoh, Jaehyuk; Jeong, Jiyoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

DHR systems consist of two diverse heat removal loops such as passive and active DHR systems, and the heat load imposed on the primary sodium pool is safely rejected into the environment through different kinds of sodium-to-air heat exchangers, e.g. M-shape and helical-coil type air-coolers. The former is called as an FHX(Forced-draft sodium-to-air Heat Exchanger) and the latter is simply called as an AHX(natural-draft sodium-to-Air Heat Exchanger). In a general sodium-to-air heat exchanger design, convection resistance in a shell-side air flow path becomes dominant factor affecting the mechanism of conjugate heat transfer from the sodium flow inside the tube to the air path across the sodium tube wall. Hence verification of the flow and heat transfer characteristics is one of the most important tasks to demonstrate decay heat removal performance. To confirm a kind of ultimate heat sink heat exchanger, a medium-scale Sodium thermal-hydraulic Experiment Loop for Finned-tube sodium-to-Air Heat exchanger (here after called the SELFA) has been designed and is recently being constructed at KAERI site. The introduction of the flow baffle inside the upper sodium chamber of the model FHX unit in the SELFA facility is briefly proposed and discussed as well. The present study aims at introducing a flow baffle design inside the upper sodium chamber to make more equalized flowrates flowing into each heat transfer tube of the model FHX unit. In the cases without the flow baffle geometry, it was observed lager discrepancies in flowrates at the heat transfer tubes. However it was also found that those kinds of discrepancies could be definitely decreased at around 1/10 by employing a flow baffle.

Response of secondary containment to presence of sodium and hydrogen

International Nuclear Information System (INIS)

Gleikler, E.L.; Huang, T.C.

1979-07-01

As part of an effort to demonstrate that the risk to the public from extremely low probability events in liquid metal fast breeder reactors is bound within an acceptable envelope, containment pressurization by sodium and hydrogen was evaluated. Temperature and pressure histories are presented for typical sodium spray and pool fires and sodium vapor reactions. A review of mechanisms for hydrogen generation and recombination as well as limit for flammability and autocatalytic recombination is provided, and general containment design options to reduce risk are discussed

Isotope exchange between gaseous hydrogen and uranium hydride powder

International Nuclear Information System (INIS)

Shugard, Andrew D.; Buffleben, George M.; Johnson, Terry A.; Robinson, David B.

2014-01-01

Highlights: • Isotope exchange between hydrogen gas and uranium hydride powder can be rapid and reversible. • Gas–solid exchange rate is controlled by transport within ∼0.7 μm hydride particles. • Gas chromatographic separation of hydrogen isotopes using uranium hydride is feasible. - Abstract: Isotope exchange between gaseous hydrogen and solid uranium hydride has been studied by flowing hydrogen (deuterium) gas through packed powder beds of uranium deuteride (hydride). We used a residual gas analyzer system to perform real-time analysis of the effluent gas composition. We also developed an exchange and transport model and, by fitting it to the experimental data, extracted kinetic parameters for the isotope exchange reaction. Our results suggest that, from approximately 70 to 700 kPa and 25 to 400 °C, the gas-to-solid exchange rate is controlled by hydrogen and deuterium transport within the ∼0.7 μm diameter uranium hydride particles. We use our kinetic parameters to show that gas chromatographic separation of hydrogen and deuterium using uranium hydride could be feasible

Hydrogen determination in magnesium, zirconium, sodium and lithium using installation, C2532

International Nuclear Information System (INIS)

Malikova, E.D.; Velyukhanov, V.P.; Makhinova, L.O.; Kunin, L.L.

1980-01-01

Techniques of hydrogen determination in magnesium, lithium, sodium and zirconium using the S 2532 installation are developed. The method of oxidizing melting using lead borate has been used for hydrogen determination in lithium and sodium and the method of vacuum extraction - for hydrogen determination in zirconium and magnesium. Zr and Mg extraction has been carried out in steel reactor at the temperatures of 1000 and 650 deg C, the time of extraction being 30 and 10 minutes respectively. A quartz reactor, temperatures of oxidizing melting of 700-800 deg C, the time of analysis 10 and 20 minutes have been used for sodium and lithium. A possibility to determine volumetric content of hydrogen in magnesium at the existing surface contaminations with hydrogen-containing compounds is shown [ru

Efficacy of formalin, hydrogen-peroxide, and sodium-chloride on fungal-infected rainbow-trout eggs

Science.gov (United States)

Schreier, Theresa M.; Rach, J.J.; Howe, G.E.

1996-01-01

Antifungal agents are essential for the maintenance of healthy stocks of fish and their eggs in intensive aquaculture operations. In the usa, formalin is the only fungicide approved for use in fish culture, however, hydrogen peroxide and sodium chloride have been granted low regulatory priority drug status by the united states food and drug administration (fda) and their use is allowed. We evaluated the efficacy of these fungicides for controlling fungal infections on rainbow trout eggs. A pilot study was conducted to determine the minimum water flow rate required to administer test chemicals accurately in heath incubators. A minimum water flow rate of 7.6 1 min(-1) was necessary to maintain treatment concentrations during flow-through chemical exposures, the antifungal activity of formalin, hydrogen peroxide, and sodium chloride was evaluated by treating uninfected and 10% fungal-infected (saprolegnia parasitica) rainbow trout eggs (oncorhynchus mykiss) for 15 min every other day until hatch. There were no significant differences among treatments in percent hatch or final infection for uninfected eggs receiving prophylactic chemical treatments, eggs of the negative control group (uninfected and untreated) had a mean hatch exceeding 86%, all chemical treatments conducted on the infected egg groups controlled the spread of fungus and improved hatching success compared with the positive control groups (infected and untreated), formalin treatments of 1000 and 1500 mu l 1(-1) and hydrogen peroxide treatments of 500 and 1000 mu l 1(-1) were the most effective. Sodium chloride treatments of 30000 mg 1(-1) improved fry hatch, but the compound was less effective at inhibiting fungal growths compared with hydrogen peroxide and formalin treatments.

Separation of uranium from sodium carbonate - sodium bicarbonate eluate by ion exchange method

International Nuclear Information System (INIS)

Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Katoh, Shunsaku; Sugasaka, Kazuhiko

1982-01-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na 2 CO 3 -0.5 N NaHCO 3 ) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/1 uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluant (5 % NaCl-0.5 % Na 2 CO 3 ). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased. (author)

Separation of uranium from sodium carbonate-sodium bicarbonate eluate by ion exchange method

International Nuclear Information System (INIS)

Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Katoh, Shunsaku; Sugasaka, Kazuhiko

1982-01-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na 2 CO 3 -0.5 N NaHCO 3 ) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/l uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluent (5% NaCl-0.5% Na 2 CO 3 ). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased. (author)

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.)

Current status of restoration work for obstacle and supper core structure in reactor vessel of experimental fast reactor 'JOYO'. 3. Sodium purification operation after MARICO recovery and UCS exchange work

International Nuclear Information System (INIS)

Shimizu, Shunji; Izawa, Osamu; Ishizaki, Kazuhiko; Takeishi, Tsuyoshi; Oowada, Ryohei; Yoshihara, Shizuya; Michino, Masanobu

2015-01-01

At fast-breeder reactor 'Joyo', in order to restore the partial inhibition of the rotating plug fuel exchange function due to interference with 'experimental apparatus with instrumentation lines (MARICO-2)', which occurred in May 2007, a recovery work was performed. The replacement work of the upper core structure and the recovery of sample part of the experimental apparatus with instrumentation lines were carried out under conditions where the primary system sodium was drained and the liquid level of reactor vessel was lowered. During the pulling-up work of upper core structure, an increase in nitrogen and hydrogen concentrations in the reactor vessel cover gas (argon) was confirmed through the measurement of the primary system gas chromatograph. This was due to the intrusion of air caused by the opening of the cover gas boundary. Since entrained oxygen reacted with sodium in the reactor, the purity of sodium was reduced. When this sodium is purified according to common method, the sodium with decreased purity defuses through the entire primary cooling system, causing various adverse effects. A safe and reliable procedure to purify sodium while preventing the adverse effects was examined and practiced. (A.O.)

Instrumentation and Control Systems for Sodium thermal hydraulic Experiment Loop for Finned-tube sodium-to-Air heat exchanger (SELFA)

Energy Technology Data Exchange (ETDEWEB)

Kim, Byeong Yeon; Kim, Hyung Mo; Cho, Youn Gil; Kim, Jong Man; Ko, Yung Joo; Kang, Byeong Su; Jung, Min Hwan; Jeong, Ji Young [KAERI, Daejeon (Korea, Republic of)

2016-05-15

A forced-draft sodium-to-air heat exchanger (FHX) is a part of decay heat removal system (DHRS) in Prototype Gen-IV Sodium-cooled fast reactor (PGSFR), which is being developed at Korea Atomic Energy Research Institute (KAERI). Sodium thermal hydraulic Experiment Loop for Finned-tube sodium-to-Air heat exchanger (SELFA) is a test facility for verification and validation of the design code for a forced-draft sodium-to-air heat exchanger (FHX). In this paper, we have provided design and fabrication features for the instrumentation and control systems of SELFA. In general, the instrumentation systems and control systems are coupled for measurement and control of process variables. Instrumentation systems have been designed for investigating thermal-hydraulic characteristics of FHX and control systems have been designed to control the main components (e.g. electromagnetic pumps, heaters, valves etc.) required for test in SELFA. In this paper, we have provided configurations of instrumentation and control systems for Sodium thermal hydraulic Experiment Loop for Finned-tube sodium-to-Air heat exchanger (SELFA). The instrumentation and control systems of SELFA have been implemented based on the expected operation ranges and lesson learned from operational experience of 'Sodium integral effect test loop for safety simulation and assessment-1' (STELLA-1)

Separation of uranium from sodium carbonate - sodium bicarbonate eluate by ion exchange method

Energy Technology Data Exchange (ETDEWEB)

Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Katoh, Shunsaku; Sugasaka, Kazuhiko (Government Industrial Research Inst., Shikoku, Takamatsu (Japan))

1982-09-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na/sub 2/CO/sub 3/-0.5 N NaHCO/sub 3/) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/1 uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluant (5 % NaCl-0.5 % Na/sub 2/CO/sub 3/). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased.

Separation of uranium from sodium carbonate-sodium bicarbonate eluate by ion exchange method

Energy Technology Data Exchange (ETDEWEB)

Sakane, K.; Hirotsu, T.; Fujii, A.; Katoh, S.; Sugasaka, K. (Government Industrial Research. Inst., Shikoku, Takamatsu (Japan))

1982-01-01

The ion exchange method was used for separating uranium from the eluate (0.5 N Na/sub 2/CO/sub 3/-0.5 N NaHCO/sub 3/) that was obtained in the extraction process of uranium from natural sea water by using the titanium-activated carbon composite adsorbent. Uranium in the eluate containing 3 mg/l uranium was adsorbed by ion exchange resin (Amberlite IRA-400), and was eluted with the eluent (5% NaCl-0.5% Na/sub 2/CO/sub 3/). The concentration ratio of uranium in the final concentrated-eluate became more than 20 times. The eluting solution to the adsorbent and the eluant to the resin could be repeatedly used in the desorption-ion exchange process. Sodium carbonate was consumed at the desorption step, and sodium bicarbonate was consumed at the ion exchange step. The concentration ratio of uranium was found to decrease as chloride ion in the eluate increased.

Process for exchanging hydrogen isotopes between gaseous hydrogen and water

International Nuclear Information System (INIS)

Hindin, S.G.; Roberts, G.W.

1977-01-01

A process is described for exchanging isotopes (particularly tritium) between water and gaseous hydrogen. Isotope depleted gaseous hydrogen and water containing a hydrogen isotope are introduced into the vapour phase in a first reaction area. The steam and gaseous hydrogen are brought into contact with a supported metal catalyst in this area in a parallel flow at a temperature range of around 225 and 300 0 C. An effluent flow comprising a mixture of isotope enriched gaseous hydrogen and depleted steam is evacuated from this area and the steam condensed into liquid water [fr

Trends in the exchange current for hydrogen evolution

DEFF Research Database (Denmark)

Nørskov, Jens Kehlet; Bligaard, Thomas; Logadottir, Ashildur

2005-01-01

A density functional theory database of hydrogen chemisorption energies on close packed surfaces of a number of transition and noble metals is presented. The bond energies are used to understand the trends in the exchange current for hydrogen evolution. A volcano curve is obtained when measured...... exchange currents are plotted as a function of the calculated hydrogen adsorption energies and a simple kinetic model is developed to understand the origin of the volcano. The volcano curve is also consistent with Pt being the most efficient electrocatalyst for hydrogen evolution. (c) 2005...

Deuterium exchange between liquid water and gaseous hydrogen

International Nuclear Information System (INIS)

Dave, S.M.; Ghosh, S.K.; Sadhukhan, H.K.

1982-01-01

The overall separation factors for the deuterium exchange between liquid water and gaseous hydrogen have been calculated over a wide range of temperature, pressure and deuterium concentrations. These data would be useful in the design and other considerations for heavy water production, based on hydrogen-water exchange. (author)

Ultrahigh figure-of-merit for hydrogen generation from sodium borohydride using ternary metal catalysts

Science.gov (United States)

Hu, Lunghao; Ceccato, R.; Raj, R.

We report further increase in the figure-of-merit (FOM) for hydrogen generation from NaBH 4 than reported in an earlier paper [1], where a sub-nanometer layer of metal catalysts are deposited on carbon nanotube paper (CNT paper) that has been functionalized with polymer-derived silicon carbonitride (SiCN) ceramic film. Ternary, Ru-Pd-Pt, instead of the binary Pd-Pt catalyst used earlier, together with a thinner CNT paper is shown to increase the figure-of-merit by up to a factor of six, putting is above any other known catalyst for hydrogen generation from NaBH 4. The catalysts are prepared by first impregnating the functionalized CNT-paper with solutions of the metal salts, followed by reduction in a sodium borohydride solution. The reaction mechanism and the catalyst efficiency are described in terms of an electric charge transfer, whereby the negative charge on the BH 4 - ion is exchanged with hydrogen via the electronically conducting SiCN/CNT substrate [1].

Selective hydrogenation of 4-isobutylacetophenone over a sodium-promoted Pd/C catalyst

International Nuclear Information System (INIS)

Cho, Hong-Baek; Lee, Bae Uk; Nakayama, Tadachika; Park, Yeung-Ho; Ryu, Chung-Han

2013-01-01

The effect of sodium promotion on the selective hydrogenation of 4-isobutylacetophenone, 4-IBAP, was investigated over a Pd/C catalyst. A precipitation and deposition method was used to prepare the catalyst, and sodium was promoted on the Pd/C catalyst via post-impregnation while varying the sodium content. The sodium-promoted Pd/C catalyst resulted in a significantly improved yield greater than 96% of the desired product, 1-(4-isobutylphenyl) ethanol (4-IBPE), compared with the non-patented literature results under a mild hydrogenation condition. A detailed hydrogenation network over the Pd/C catalyst was suggested. The reaction mechanism for the yield and selectivity enhancement of 4-IBPE induced-by the promoted Pd/C was elucidated in relation to the geometric and electronic effects of reactant molecules in the microporous support depending on the reaction steps

NMR studies of the influence of dodecyl sulfate on the amide hydrogen exchange kinetics of a micelle-solubilized hydrophobic tripeptide

International Nuclear Information System (INIS)

O'Neil, J.D.J.; Sykes, B.D.

1989-01-01

Backbone amide hydrogen exchange measurements are an important source of information about the internal dynamics of proteins. Before such measurements can be interpreted unambiguously, contributions to hydrogen exchange rates from the chemical and physical environment of the amides must be taken into account. Membrane proteins are often solubilized in detergents, yet there have not been any systematic investigations of the possible effects detergents may have on the amide hydrogen exchange rates of proteins. To address this question, the authors have measured individual backbone and carboxyl-terminal amide exchange rates for the amphipathic tripeptide Leu-Val-Ile-amide dissolved in water and dodecyl sulfate micelles. Proton NMR spectroscopy was used to measure exchange using the direct exchange-out into D 2 O technique at 5 degree C and using an indirect steady-state saturation-transfer technique at 25 degree C. The broadening effect of micelle-incorporated spin-labeled fatty acid (12-doxylsterate) on the 1 H NMR spectra of both the detergent and the peptide resonances was used to demonstrate that the tripeptide is intimately associated with the micelle. These experiments help to explain the elevated pH min observed for backbone amides in the sodium dodecyl sulfate solubilized M13 coat protein

Bacteria and Acidic Drainage from Coal Refuse: Inhibition by Sodium Lauryl Sulfate and Sodium Benzoate

OpenAIRE

Dugan, Patrick R.; Apel, William A.

1983-01-01

The application of an aqueous solution of sodium lauryl sulfate and sodium benzoate to the surface of high-sulfur coal refuse resulted in the inhibition of iron-and sulfur-oxidizing chemoautotrophic bacteria and in the decrease of acidic drainage from the refuse, suggesting that acid drainage can be abated in the field by inhibiting iron- and sulfur-oxidizing bacteria.

Hydrogen-water isotopic exchange process

International Nuclear Information System (INIS)

Cheung, H.

1984-01-01

The objects of this invention are achieved by a dual temperature isotopic exchange process employing hydrogen-water exchange with water passing in a closed recirculation loop between a catalyst-containing cold tower and the upper portion of a catalyst-containing hot tower, with feed water being introduced to the lower portion of the hot tower and being maintained out of contact with the water recirculating in the closed loop. Undue retarding of catalyst activity during deuterium concentration can thus be avoided. The cold tower and the upper portion of the hot tower can be operated with relatively expensive catalyst material of higher catalyst activity, while the lower portion of the hot tower can be operated with a relatively less expensive, more rugged catalyst material of lesser catalyst activity. The feed water stream, being restricted solely to the lower portion of the hot tower, requires minimal pretreatment for the removal of potential catalyst contaminants. The catalyst materials are desirably coated with a hydrophobic treating material so as to be substantially inaccessible to liquid water, thereby retarding catalyst fouling while being accessible to the gas for enhancing isotopic exchange between hydrogen gas and water vapor. A portion of the water of the closed loop can be passed to a humidification zone to heat and humidify the circulating hydrogen gas and then returned to the closed loop

Sodium borohydride hydrogen generator using Co–P/Ni foam catalysts for 200 W proton exchange membrane fuel cell system

International Nuclear Information System (INIS)

Oh, Taek Hyun; Gang, Byeong Gyu; Kim, Hyuntak; Kwon, Sejin

2015-01-01

The response characteristics of electroless-deposited Co–P/Ni foam catalysts for sodium borohydride hydrolysis were investigated. The effect of nickel foam geometry on the properties of the catalysts was evaluated. As the PPI (pores per inch) of the nickel foam increased, the hydrogen generation rate per gram of the deposited catalyst increased due to an increase in surface area. The response characteristics of various catalysts were compared under real operating conditions. When a thin nickel foam with high PPI was used, the response characteristics of the catalyst improved due to an increase in the amount of the deposited catalyst and surface area. Finally, a 200 W PEMFC (proton exchange membrane fuel cell) system using electroless-deposited Co–P/Ni foam (110 PPI) catalyst was investigated. The response time to reach a hydrogen generation rate sufficient for a 200 W PEMFC was 71 s, and the energy density of a 200 W fuel cell system for producing 600 Wh was 252.1 Wh/kg. A fuel cell system using Co–P/Ni foam catalysts can be widely used as a power source for mobile applications due to fast response characteristics and high energy density. - Highlights: • Response characteristics of Co–P/Ni foam catalysts are investigated. • Catalytic activity is improved with increase in PPI (pores per inch) of Ni foam. • Co–P/Ni foam (110 PPI) catalyst has improved response characteristics. • The energy density of a 200 W PEMFC system for producing 600 Wh is 252.1 Wh/kg. • Co–P/Ni foam (110 PPI) catalyst is suitable for fuel cell system.

Tritium removal by hydrogen isotopic exchange between hydrogen gas and water on hydrophobic catalyst

International Nuclear Information System (INIS)

Morishita, T.; Isomura, S.; Izawa, H.; Nakane, R.

1980-01-01

Many kinds of the hydrophobic catalysts for hydrogen isotopic exchange between hydrogen gas and water have been prepared. The carriers are the hydrophobic organic materials such as polytetrafluoroethylene(PTFE), monofluorocarbon-PTFE mixture(PTFE-FC), and styrene-divinylbenzene copolymer(SDB). 0.1 to 2 wt % Pt is deposited on the carriers. The Pt/SDB catalyst has much higher activity than the Pt/PTFE catalyst and the Pt/PTFE-FC catalyst shows the intermediate value of catalytic activity. The observation of electron microscope shows that the degrees of dispersion of Pt particles on the hydrophobic carriers result in the difference of catalytic activities. A gas-liquid separated type column containing ten stages is constructed. Each stage is composed of both the hydrophobic catalyst bed for the hydrogen gas/water vapor isotopic exchange and the packed column type bed for the water vapor/liquid water isotopic exchange. In the column hydrogen gas and water flow countercurrently and hydrogen isotopes are separated

Bacteria and Acidic Drainage from Coal Refuse: Inhibition by Sodium Lauryl Sulfate and Sodium Benzoate

Science.gov (United States)

Dugan, Patrick R.; Apel, William A.

1983-01-01

The application of an aqueous solution of sodium lauryl sulfate and sodium benzoate to the surface of high-sulfur coal refuse resulted in the inhibition of iron-and sulfur-oxidizing chemoautotrophic bacteria and in the decrease of acidic drainage from the refuse, suggesting that acid drainage can be abated in the field by inhibiting iron- and sulfur-oxidizing bacteria. PMID:16346347

Isotopic exchange of carbon-bound hydrogen over geologic timescales

Science.gov (United States)

Sessions, Alex L.; Sylva, Sean P.; Summons, Roger E.; Hayes, John M.

2004-04-01

The increasing popularity of compound-specific hydrogen isotope (D/H) analyses for investigating sedimentary organic matter raises numerous questions about the exchange of carbon-bound hydrogen over geologic timescales. Important questions include the rates of isotopic exchange, methods for diagnosing exchange in ancient samples, and the isotopic consequences of that exchange. This article provides a review of relevant literature data along with new data from several pilot studies to investigate such issues. Published experimental estimates of exchange rates between organic hydrogen and water indicate that at warm temperatures (50-100°C) exchange likely occurs on timescales of 104 to 108 yr. Incubation experiments using organic compounds and D-enriched water, combined with compound-specific D/H analyses, provide a new and highly sensitive method for measuring exchange at low temperatures. Comparison of δD values for isoprenoid and n-alkyl carbon skeletons in sedimentary organic matter provides no evidence for exchange in young (exchange in ancient (>350 Ma) rocks. Specific rates of exchange are probably influenced by the nature and abundance of organic matter, pore-water chemistry, the presence of catalytic mineral surfaces, and perhaps even enzymatic activity. Estimates of equilibrium fractionation factors between organic H and water indicate that typical lipids will be depleted in D relative to water by ∼75 to 140‰ at equilibrium (30°C). Thus large differences in δD between organic molecules and water cannot be unambiguously interpreted as evidence against hydrogen exchange. A better approach may be to use changes in stereochemistry as a proxy for hydrogen exchange. For example, estimated rates of H exchange in pristane are similar to predicted rates for stereochemical inversion in steranes and hopanes. The isotopic consequences of this exchange remain in question. Incubations of cholestene with D2O indicate that the number of D atoms incorporated during

Contribution to the study of hydrogenated and oxygenated impurities in liquid sodium

International Nuclear Information System (INIS)

Naud, G.

1964-07-01

This study is made up essentially of two parts. The first is devoted to the development of dosage methods for selectively determining the oxygenated and hydrogenated impurities present in sodium, that is the oxide, the hydride and the hydroxide. The second makes use of these methods for a study of the Na-H 2 -O 2 system, as well as of the related problem of the attack of pyrex glass by molten sodium. The conventional method for dosing oxygen by amalgamation was first adapted to the simultaneous measurement of the hydride. We then developed a method for dosing the total hydrogen by measuring successively the concentrations of gas present in the hydride and hydroxide form. This method is based on the thermal decomposition of the hydride and the reaction between sodium and the hydroxide. Our contribution to the study of the Na-H 2 -O 2 System consists first of all in the study of the reaction between hydrogen and sodium in the temperature range from 150 to 250 deg C and at a pressure of about 150 mm of mercury. The study of the thermal decomposition of the hydride in sodium was then studied. It was possible to make some qualitative observations concerning the reaction between sodium and sodium hydroxide. Finally some complementary tests made it possible to define the nature of the phenomena occurring during the attack of pyrex glass by sodium. (author) [fr

The monitoring of oxygen, hydrogen and carbon in the sodium circuits of the PFR

International Nuclear Information System (INIS)

Mason, L.; Morrison, N.S.; Robertson, C.M.; Trevillion, E.A.

1984-01-01

The paper reviews the instrumentation available for monitoring oxygen, hydrogen, tritium and carbon impurity levels on the primary and secondary circuits of PFR. Circuit oxygen levels measured using electrochemical oxygen meters are compared to estimates from circuit plugging meters. The data are interpreted in the light of information from cold trap temperatures. Measurements of secondary circuit hydrogen levels using both the sodium and gas phase hydrogen detection equipment are compared to estimates of circuit hydrogen levels from plugging meters and variations in sodium phase hydrogen levels during power operation are discussed. (author)

Exchange reaction between tritiated hydrogen and water vapor

International Nuclear Information System (INIS)

Yamada, Koichi; Takano, Kenichi; Watanabe, Tamaki.

1979-01-01

Exchange reaction of tritiated hydrogen to water vapor under the condition of tritium gas concentration between 1 μCi/l and 1 mCi/l was studied. Tritium gas with hydrogen gas of 5 Torr and water of 20 mg were enclosed in a Pyrex glass ampule with volume of about 100 ml. The mixed gas with water vapor was heated with electric furnace. The heating time was between 2 and 100 hr, and the temperature was 776, 725, 675, 621, and 570.5 0 K. After heating, tritiated water was trapped with liquid nitrogen, and counted with a liquid scintillation counter. The radioactive concentration of initial tritiated hydrogen was measured with a calibrated ionization chamber. The main results obtained are as follows; 1) the concentration of produced tritiated water is well proportioned to that of initial tritiated hydrogen, 2) the activation energy of exchange reaction from tritiated hydrogen to tritiated water is 26.2 kcal/mol and that of inverse reaction is 27.4 kcal/mol, 3) the reaction rate at room temperature which calculated with activation energy is 1.04 x 10 -13 day -1 , and then exchange reaction at room temperature is negligible. (author)

Isotope exchange reactions in hydrogen mixtures

International Nuclear Information System (INIS)

Czaplinski, W.; Gula, A.; Kravtsov, A.; Mikhailov, A.; Popov, N.

1990-12-01

The rates of isotopic exchange for the excited states of muonic hydrogen are calculated as functions of collision energy. Ground state population q 1s for different collision energies, target densities and isotope concentrations is obtained. It is shown that for principal quantum numbers n > 5 the isotopic exchange still considerably influences the value of q 1s . (author)

Novel catalysts for isotopic exchange between hydrogen and liquid water

International Nuclear Information System (INIS)

Butler, J.P.; Rolston, J.H.; Stevens, W.H.

1978-01-01

Catalytic isotopic exchange between hydrogen and liquid water offers many inherent potential advantages for the separation of hydrogen isotopes which is of great importance in the Canadian nuclear program. Active catalysts for isotopic exchange between hydrogen and water vapor have long been available, but these catalysts are essentially inactive in the presence of liquid water. New, water-repellent platinum catalysts have been prepared by: (1) treating supported catalysts with silicone, (2) depositing platinum on inherently hydrophobic polymeric supports, and (3) treating platinized carbon with Teflon and bonding to a carrier. The activity of these catalysts for isotopic exchange between countercurrent streams of liquid water and hydrogen saturated with water vapor has been measured in a packed trickle bed integral reactor. The performance of these hydrophobic catalysts is compared with nonwetproofed catalysts. The mechanism of the overall exchange reaction is briefly discussed. 6 figures

Paradoxical Effects of Sodium-Calcium Exchanger Inhibition on Torsade de Pointes and Early Afterdepolarization in a Heart Failure Rabbit Model.

Science.gov (United States)

Chang, Po-Cheng; Lu, Yu-Ying; Lee, Hui-Ling; Lin, Shien-Fong; Chu, Yen; Wen, Ming-Shien; Chou, Chung-Chuan

2018-05-03

Calcium homeostasis plays an important role in development of early afterdepolarizations (EADs) and torsade de pointes (TdP). The role of sodium-calcium exchanger (NCX) inhibition in genesis secondary Ca rise and EADs-TdP is still debated. Dual voltage and intracellular Ca optical mapping were conducted in 6 control and 9 failing rabbit hearts. After baseline electrophysiological and optical mapping studies, E4031 was given to simulate long QT syndrome. ORM-10103 was then administrated to examine the electrophysiological effects on EAD-TdP development. E4031 enhanced secondary Ca rise, EADs development and TdP inducibility in both control and failing hearts. The results showed that ORM-10103 reduced premature ventricular beats (PVBs) but was unable to suppress the inducibility of TdP or EADs. The electrophysiological effects of ORM-10103 included prolongation of action potential duration (APD) and increased APD heterogeneity in failing hearts. ORM10103 had a neutral effect on the amplitude of secondary Cai rise in control and HF groups. In this model, most EADs generated from the long-short APD junction area. In conclusion, highly selective NCX inhibition with ORM-10103 reduced PVB burden but was unable to suppress secondary Ca rise, EADs development nor inducibility of TdP. The possible electrophysiological mechanisms include APD prolongation and increased APD heterogeneity.

Studying inhibition of calcium oxalate stone formation: an in vitro approach for screening hydrogen sulfide and its metabolites

Directory of Open Access Journals (Sweden)

S. Vaitheeswari

2015-06-01

Full Text Available ABSTRACTPurpose:Calcium oxalate urolithiasis is one of the most common urinary tract diseases and is of high prevalence. The present study proposes to evaluate the antilithiatic property of hydrogen sulfide and its metabolites like thiosulfate & sulfate in an in vitro model.Materials and Methods:The antilithiatic activity of sodium hydrogen sulfide (NaSH, sodium thiosulfate (Na2S2O3 and sodium sulfate (Na2SO4 on the kinetics of calcium oxalate crystal formation was investigated both in physiological buffer and in urine from normal and recurrent stone forming volunteers. The stones were characterized by optical and spectroscopic techniques.Results:The stones were characterized to be monoclinic, prismatic and bipyramidal habit which is of calcium monohydrate and dihydrate nature. The FTIR displayed fingerprint corresponding to calcium oxalate in the control while in NaSH treated, S=O vibrations were visible in the spectrum. The order of percentage inhibition was NaSH>Na2S2O3>Na2SO4.Conclusion:Our study indicates that sodium hydrogen sulfide and its metabolite thiosulfate are inhibitors of calcium oxalate stone agglomeration which makes them unstable both in physiological buffer and in urine. This effect is attributed to pH changes and complexing of calcium by S2O32-and SO42- moiety produced by the test compounds.

Inhibition of cardiac sodium currents by toluene exposure

Science.gov (United States)

Cruz, Silvia L; Orta-Salazar, Gerardo; Gauthereau, Marcia Y; Millan-Perez Peña, Lourdes; Salinas-Stefanón, Eduardo M

2003-01-01

Toluene is an industrial solvent widely used as a drug of abuse, which can produce sudden sniffing death due to cardiac arrhythmias. In this paper, we tested the hypothesis that toluene inhibits cardiac sodium channels in Xenopus laevis oocytes transfected with Nav1.5 cDNA and in isolated rat ventricular myocytes. In oocytes, toluene inhibited sodium currents (INa+) in a concentration-dependent manner, with an IC50 of 274 μM (confidence limits: 141–407μM). The inhibition was complete, voltage-independent, and slowly reversible. Toluene had no effect on: (i) the shape of the I–V curves; (ii) the reversal potential of Na+; and (iii) the steady-state inactivation. The slow recovery time constant from inactivation of INa+ decreased with toluene exposure, while the fast recovery time constant remained unchanged. Block of INa+ by toluene was use- and frequency-dependent. In rat cardiac myocytes, 300 μM toluene inhibited the sodium current (INa+) by 62%; this inhibition was voltage independent. These results suggest that toluene binds to cardiac Na+ channels in the open state and unbinds either when channels move between inactivated states or from an inactivated to a closed state. The use- and frequency-dependent block of INa+ by toluene might be responsible, at least in part, for its arrhythmogenic effect. PMID:14534149

NAA of ion exchanged sodium polyacrylate for monitoring air quality in the workplace

International Nuclear Information System (INIS)

Rigot, W.L.; Cutie, S.S.

2000-01-01

Sodium polyacrylate is a superabsorbent polymer (SAP) which is widely used in the manufacturing of disposable diapers. Workplace exposure to respirable dust produced from the handling of these polymers is becoming more of a concern as more data relating occupational exposures to health effects are becoming available. An approach that utilizes the fundamental ion exchange properties of the polymer combined with the sensitivity of instrumental neutron activation analysis has been developed which eliminates interferences from sodium species that are ubiquitous to manufacturing facilities. The technique involves exchanging the sodium that is associated with the polymer with europium and analyzing the exchanged polymer by neutron activation analysis. The technique is simple to run, provides excellent sensitivity and is specific to sodium polyacrylate. (author)

Inhibitive Effect of Butyltin Trichloride on Dissolution and Localized Corrosion of Aluminium in Sodium Hydroxide and Hydrochloric Acid

OpenAIRE

Mourad, M.Y.; Ibrahim, E.H.; Seliman, S.A.

1990-01-01

The dissolution of aluminium in sodium hydroxide and hydrochloric acid in the presence of butyltin trichloride as corrosion inhibitor has been studied by hydrogen evolution and thermometric methods. Experimental findings indicate that the inhibition effect of butyltin trichloride takes place through an adsorption mechanism following the Frumkin's isotherm. Butyltin trichloride acts as a weakly adsorbed inhibitor in NaOH and as a strongly adsorbed inhibitor in hydrochloric acid medium. Wile...

Studies on sorption of plutonium on inorganic exchangers from sodium carbonate medium

Energy Technology Data Exchange (ETDEWEB)

Pius, I C; Charyulu, M M; Sivaramakrishnan, C K [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India); Venkataramani, B [Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

Sorption of Pu(IV) from sodium carbonate medium has been investigated by using different inorganic exchangers alumina, silica gel and hydrous titanium oxide. Distribution ratios of Pu(IV) for its sorption on these exchangers from sodium carbonate medium were found to be sufficiently high indicating the suitability of these exchangers for the removal of Pu(IV). The presence of uranium and dibutyl phosphate do not have any effect on distribution ratio. The 10% Pu(IV) breakthrough capacities for above exchangers have been determined with 5 ml bed at a flow rate of 30 ml/hour. (author). 4 refs., 2 tabs.

Preliminary conceptual design of the secondary sodium circuit-eliminated JSFR (Japan Sodium Fast Reactor) adopting a supercritical CO2 turbine system (1). Sodium/CO2 heat exchanger

International Nuclear Information System (INIS)

Kisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji

2014-09-01

Research and development of the supercritical CO 2 (S-CO 2 ) cycle turbine system is underway in various countries for further improvement of the safety and economy of sodium-cooled fast reactors. The Component Design and Balance-Of-Plant (CD and BOP) of the Generation IV International Nuclear Forum (Gen-IV) has addressed this study, and their analytical and experimental results have been discussed between the relevant countries. JAEA, who is a member of the CD and BOP, has performed a design study of an S-CO 2 gas turbine system applied to the Japan Sodium-cooled Fast Reactor (JSFR). In this study, the S-CO 2 cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. This is because there is no risk of sodium-water reaction in the S-CO 2 cycle turbine system of SFRs. The Na/CO 2 heat exchanger is one of the key components for the secondary sodium system eliminated SFR, and this report describes its structure and the safety in case of CO 2 leak. A Printed Circuit Heat Exchanger (PCHE), which has a greater heat transfer performance, is employed to the heat exchanger. Another advantage of the PCHE is to limit the area affected by a leak of CO 2 because of its partitioned flow path structure. A SiC/SiC ceramic composite material is used for the PCHE to prevent crack growth and to reduce thermal stress. The Na/CO 2 heat exchanger has been designed in such a way that a number of small heat transfer modules are combined in the vessel in consideration of manufacture and repair. The primary sodium pump is installed in the center of the heat exchanger vessel. CO 2 leak events in the heat exchanger have been also evaluated, and it revealed that no significant effect has arisen on the core or the primary sodium boundary. (author)

Equilibrium amide hydrogen exchange and protein folding kinetics

International Nuclear Information System (INIS)

Bai Yawen

1999-01-01

The classical Linderstrom-Lang hydrogen exchange (HX) model is extended to describe the relationship between the HX behaviors (EX1 and EX2) and protein folding kinetics for the amide protons that can only exchange by global unfolding in a three-state system including native (N), intermediate (I), and unfolded (U) states. For these slowly exchanging amide protons, it is shown that the existence of an intermediate (I) has no effect on the HX behavior in an off-pathway three-state system (I↔U↔N). On the other hand, in an on-pathway three-state system (U↔I↔N), the existence of a stable folding intermediate has profound effect on the HX behavior. It is shown that fast refolding from the unfolded state to the stable intermediate state alone does not guarantee EX2 behavior. The rate of refolding from the intermediate state to the native state also plays a crucial role in determining whether EX1 or EX2 behavior should occur. This is mainly due to the fact that only amide protons in the native state are observed in the hydrogen exchange experiment. These new concepts suggest that caution needs to be taken if one tries to derive the kinetic events of protein folding from equilibrium hydrogen exchange experiments

1H NMR studies of substrate hydrogen exchange reactions catalyzed by L-methionine gamma-lyase

International Nuclear Information System (INIS)

Esaki, N.; Nakayama, T.; Sawada, S.; Tanaka, H.; Soda, K.

1985-01-01

Hydrogen exchange reactions of various L-amino acids catalyzed by L-methionine gamma-lyase (EC 4.4.1.11) have been studied. The enzyme catalyzes the rapid exchange of the alpha- and beta-hydrogens of L-methionine and S-methyl-L-cysteine with deuterium from the solvent. The rate of alpha-hydrogen exchange was about 40 times faster than that of the enzymatic elimination reaction of the sulfur-containing amino acids. The enzyme also catalyzes the exchange reaction of alpha- and beta-hydrogens of the straight-chain L-amino acids which are not susceptible to elimination. The exchange rates of the alpha-hydrogen and the total beta-hydrogens of L-alanine and L-alpha-aminobutyrate with deuterium followed first-order kinetics. For L-norvaline, L-norleucine, S-methyl-L-cysteine, and L-methionine, the rate of alpha-hydrogen exchange followed first-order kinetics, but the rate of total beta-hydrogen exchange decreased due to a primary isotope effect at the alpha-position. L-Phenylalanine and L-tryptophan slowly underwent alpha-hydrogen exchange. The pro-R hydrogen of glycine was deuterated stereospecifically

Hydrogen, deuterium, and tritium isotope exchange experiments in JET

Energy Technology Data Exchange (ETDEWEB)

Horton, L.D.; Andrew, P.; Bracco, G.; Conroy, S.; Corti, S.; Ehrenberg, J.; Goodall, D.H.J.; Jarvis, O.N.; Lomas, P.; Loughlin, M.; Peacock, A.T.; Saibene, G.; Sadler, G.; Sartori, R.; Stamp, M.F.; Thomas, P.R.; Belle, P. van (JET Joint Untertaking, Abingdon, Oxfordshire (United Kingdom))

1992-12-01

Isotope exchange experiments have been performed in JET using hydrogen, deuterium, and, in the recent preliminary tritium experiment (PTE), tritium. The rate of change-over from one isotope to another involves two quite different time constants. We have modelled this behaviour using a multireservoir model which splits the accessible hydrogenic particles into two groups, each having a different rate of exchange of particles with the plasma. By applying this model to the sequence of discharges during and after the PTE, we can determine the parameters in the model. The resulting fit also gives a good representation of hydrogen/deuterium change-over experiments, indicating that the tritium behaves in the same manner as other hydrogen isotopes, at least as far as recycling is concerned. Discrepancies between the model and the actual measurements of tritium recovery after the PTE lead us to conclude that isotope exchange processes resulting from collisions of molecules with the vessel walls play a significant role in spreading tritrium around the machine. (orig.).

Catalyst for hydrogen-amine D exchange

International Nuclear Information System (INIS)

Holtslander, W.J.; Johnson, R.E.

1976-01-01

A process is claimed for deuterium isotopic enrichment (suitable for use in heavy water production) by amine-hydrogen exchange in which the exchange catalyst comprises a mixture of alkyl amides of two metals selected from the group consisting of the alkali metals. Catalyst mixtures comprising at least one of the alkali amides of lithium and potassium are preferred. At least one of the following benefits are obtained: decreased hydride formation, decreased thermal decomposition of alkyl amide, increased catalyst solubility in the amine phase, and increased exchange efficiency. 11 claims

Ultrafast dynamics of hydrogen bond exchange in aqueous ionic solutions.

Science.gov (United States)

Park, Sungnam; Odelius, Michael; Gaffney, Kelly J

2009-06-04

The structural and dynamical properties of aqueous ionic solutions influence a wide range of natural and biological processes. In these solutions, water has the opportunity to form hydrogen bonds with other water molecules and anions. Knowing the time scale with which these configurations interconvert represents a key factor to understanding the influence of molecular scale heterogeneity on chemical events in aqueous ionic solutions. We have used ultrafast IR spectroscopy and Car-Parrinello molecular dynamics (CPMD) simulations to investigate the hydrogen bond (H-bond) structural dynamics in aqueous 6 M sodium perchlorate (NaClO4) solution. We have measured the H-bond exchange dynamics between spectrally distinct water-water and water-anion H-bond configurations with 2DIR spectroscopy and the orientational relaxation dynamics of water molecules in different H-bond configurations with polarization-selective IR pump-probe experiments. The experimental H-bond exchange time correlates strongly with the experimental orientational relaxation time of water molecules. This agrees with prior observations in water and aqueous halide solutions, and has been interpreted within the context of an orientational jump model for the H-bond exchange. The CPMD simulations performed on aqueous 6 M NaClO4 solution clearly demonstrate that water molecules organize into two radially and angularly distinct structural subshells within the first solvation shell of the perchlorate anion, with one subshell possessing the majority of the water molecules that donate H-bonds to perchlorate anions and the other subshell possessing predominantly water molecules that donate two H-bonds to other water molecules. Due to the high ionic concentration used in the simulations, essentially all water molecules reside in the first ionic solvation shells. The CPMD simulations also demonstrate that the molecular exchange between these two structurally distinct subshells proceeds more slowly than the H

Wustite-based photoelectrodes with lithium, hydrogen, sodium, magnesium, manganese, zinc and nickel additives

Science.gov (United States)

Carter, Emily Ann; Toroker, Maytal Caspary

2017-08-15

A photoelectrode, photovoltaic device and photoelectrochemical cell and methods of making are disclosed. The photoelectrode includes an electrode at least partially formed of FeO combined with at least one of lithium, hydrogen, sodium, magnesium, manganese, zinc, and nickel. The electrode may be doped with at least one of lithium, hydrogen, and sodium. The electrode may be alloyed with at least one of magnesium, manganese, zinc, and nickel.

Hydrogen content, interfacial exchange and hydrogen diffusion in high-temperature protonic conductors based on strontium and barium cerates

International Nuclear Information System (INIS)

Vdovin, G.K.; Kurumchin, Eh.Kh.

2004-01-01

The hydrogen content and kinetics of the hydrogen exchange in the barium and strontium doped cerates are studied in the reduction atmosphere through the methods of isotope counterbalancing and isotope exchange. The measurements are carried out at 500-840 Deg C and hydrogen pressure of 2.7-16 gPa. It is established, that the hydrogen interfacial exchange proceeds at high velocities through the dissociative-type mechanisms. The effective activation energy of the hydrogen heteroexchange is determined. The coefficient of the hydrogen diffusion in BaCe 0.95 Nd 0.5 O 3-δ is calculated. The hydrogen content per formula unit constituted (0.48±0.05) in the SrCe 0.95 Y 0.05 O 3-δ and (0.60±0.05) in the BaCe 0.95 Nd 0.5 O 3-δ at 550 and 720 Deg C correspondingly and hydrogen pressure of 6.7 gPa [ru

Catalysed hydrogen isotope exchange

International Nuclear Information System (INIS)

1973-01-01

A method is described for enhancing the rate of exchange of hydrogen atoms in organic compounds or moieties with deuterium or tritium atoms. It comprises reacting the organic compound or moiety and a compound which is the source of deuterium or tritium in the presence of a catalyst consisting of a non-metallic, metallic or organometallic halide of Lewis acid character and which is reactive towards water, hydrogen halides or similar protonic acids. The catalyst is a halide or organometallic halide of: (i) zinc or another element of Group IIb; (ii) boron, aluminium or another element of Group III; (iii) tin, lead, antimony or another element of Groups IV to VI; or (iv) a transition metal, lanthanide or stable actinide; or a halohalide. (author)

Sodium-hydrogen exchanger inhibitory potential of Malus domestica, Musa × paradisiaca, Daucus carota, and Symphytum officinale.

Science.gov (United States)

Verma, Vivek; Singh, Nirmal; Jaggi, Amteshwar Singh

2014-02-01

The involvement of sodium-hydrogen exchangers (NHE) has been described in the pathophysiology of diseases including ischemic heart and brain diseases, cardiomyopathy, congestive heart failure, epilepsy, dementia, and neuropathic pain. Synthetic NHE inhibitors have not achieved much clinical success; therefore, plant-derived phytoconstituents may be explored as NHE inhibitors. In the present study, the NHE inhibitory potential of hydroalcoholic and alkaloidal fractions of Malus domestica, Musa × paradisiaca, Daucus carota, and Symphytum officinale was evaluated. The different concentrations of hydroalcoholic and alkaloidal extracts of the selected plants were evaluated for their NHE inhibitory activity in the platelets using the optical swelling assay. Among the hydroalcoholic extracts, the highest NHE inhibitory activity was shown by M. domestica (IC50=2.350 ± 0.132 μg/mL) followed by Musa × paradisiaca (IC50=7.967 ± 0.451 μg/mL), D. carota (IC50=37.667 ± 2.517 μg/mL), and S. officinale (IC50=249.330 ± 1.155 μg/mL). Among the alkaloidal fractions, the highest NHE inhibitory activity was shown by the alkaloidal fraction of Musa × paradisiacal (IC50=0.010 ± 0.001 μg/mL) followed by D. carota (IC50=0.024 ± 0.002 μg/mL), M. domestica (IC50=0.031 ± 0.005 μg/mL), and S. officinale (IC50=4.233 ± 0.379 μg/mL). The IC50 of alkaloidal fractions was comparable to the IC50 of synthetic NHE inhibitor, EIPA [5-(N-ethyl-N-isopropyl)amiloride] (IC50=0.033 ± 0.004 μg/mL). It may be concluded that the alkaloidal fractions of these plants possess potent NHE inhibitory activity and may be exploited for their therapeutic potential in NHE activation-related pathological complications.

Hydrogen Exchange Mass Spectrometry

Science.gov (United States)

Mayne, Leland

2018-01-01

Hydrogen exchange (HX) methods can reveal much about the structure, energetics, and dynamics of proteins. The addition of mass spectrometry (MS) to an earlier fragmentation-separation HX analysis now extends HX studies to larger proteins at high structural resolution and can provide information not available before. This chapter discusses experimental aspects of HX labeling, especially with respect to the use of MS and the analysis of MS data. PMID:26791986

Development of Bi-phase sodium-oxygen-hydrogen chemical equilibrium calculation program (BISHOP) using Gibbs free energy minimization method

International Nuclear Information System (INIS)

Okano, Yasushi

1999-08-01

In order to analyze the reaction heat and compounds due to sodium combustion, the multiphase chemical equilibrium calculation program for chemical reaction among sodium, oxygen and hydrogen is developed in this study. The developed numerical program is named BISHOP; which denotes Bi-Phase, Sodium - Oxygen - Hydrogen, Chemical Equilibrium Calculation Program'. Gibbs free energy minimization method is used because of the special merits that easily add and change chemical species, and generally deal many thermochemical reaction systems in addition to constant temperature and pressure one. Three new methods are developed for solving multi-phase sodium reaction system in this study. One is to construct equation system by simplifying phase, and the other is to expand the Gibbs free energy minimization method into multi-phase system, and the last is to establish the effective searching method for the minimum value. Chemical compounds by the combustion of sodium in the air are calculated using BISHOP. The Calculated temperature and moisture conditions where sodium-oxide and hydroxide are formed qualitatively agree with the experiments. Deformation of sodium hydride is calculated by the program. The estimated result of the relationship between the deformation temperature and pressure closely agree with the well known experimental equation of Roy and Rodgers. It is concluded that BISHOP can be used for evaluated the combustion and deformation behaviors of sodium and its compounds. Hydrogen formation condition of the dump-tank room at the sodium leak event of FBR is quantitatively evaluated by BISHOP. It can be concluded that to keep the temperature of dump-tank room lower is effective method to suppress the formation of hydrogen. In case of choosing the lower inflammability limit of 4.1 mol% as the hydrogen concentration criterion, formation reaction of sodium hydride from sodium and hydrogen is facilitated below the room temperature of 800 K, and concentration of hydrogen

Contribution to the study of catalytic hydrogen-deuterium exchange between hydrogen and hydrocarbons; Contribution a l'etude de l'echange catalytique hydrogene-deuterium entre l'hydrogene et les hydrocarbures

Energy Technology Data Exchange (ETDEWEB)

Ravoire, J

1958-12-20

The hydrogen-deuterium exchange between molecular hydrogen and hydrocarbons over a platinum and charcoal catalyst was studied in a static system. The change in isotopic composition of molecular hydrogen was followed by a thermal conductivity method. Cyclo-pentane and cyclohexane were chosen because of their stability. A reversible inactivation of the catalyst was observed with both hydrocarbons. The reasons for this inactivation are unknown but it was shown that reactivation led to satisfactory reproducibility. A kinetic study was done with cyclohexane in the range 30 to 160 deg. C, and 40 to 360 mm for the pressure of hydrogen, and 10 to 70 mm for the pressure of cyclohexane. The order of the reaction with respect to cyclohexane pressure is always close to zero; the order with respect to that of hydrogen is 0.5 above 100 deg. C. It decreases with increasing temperature and becomes negative (-0.5 at 30 deg. C), characterizing an inhibition by hydrogen. At the same time, the apparent activation energy goes from 6 to 13 kcal/mole. (author) [French] L'echange hydrogene-deuterium entre l'hydrogene moleculaire et les hydrocarbures sur un catalyseur au platine depose sur charbon a ete etudie a l'aide d'un appareil statique. La teneur en deuterium de L'hydrogene moleculaire a ete suivie par conductibilite thermique. Le cyclopentane et le cyclohexane ont ete choisis en raison de leur stabilite. Une desactivation reversible du catalyseur pendant son utilisation a ete observee pour les deux hydrocarbures. Les causes de la desactivation n'ont pas ete determinees, mais il a ete montre qu'une reactivation conduisait une reproductibilite satisfaisante. Une etude cinetique a ete conduite avec le cyclohexane dans le domaine: 30 deg C - 160 deg C, 40 mm - 360 mm comme pression d'hydrogene, 10 mm - 70 mm comme pression de cyclohexane. L'ordre par rapport a la pression de cyclohexane est toujours voisin de zero; l'ordre par rapport a la pression d'hydrogene est de 0,5 au-dessus de

Hydrogen generation from hydrolysis of sodium borohydride using Ru(0) nanoclusters as catalyst

International Nuclear Information System (INIS)

Ozkar, S.; Zahmakiran, M.

2005-01-01

Sodium borohydride is stable in aqueous alkaline solution, however, it hydrolyses in water to hydrogen gas in the presence of suitable catalyst. By this way hydrogen can be generated safely for the fuel cells. Generating H 2 catalytically from NaBH 4 solutions has many advantages: NaBH 4 solutions are nonflammable, reaction products are environmentally benign, rate of H 2 generation is easily controlled, the reaction product NaBO 2 can be recycled, H 2 can be generated even at low temperatures. All of the catalysts that has been used in hydrolysis of sodium borohydride are bulk metals and they act as heterogeneous catalysts. The limited surface area of the heterogeneous catalysts causes lower catalytic activity as the activity of catalyst is directly related to its surface area. Thus, the use of metal nanoparticles with large surface area provides potential route to increase the catalytic activity. Here, we report, for the first time, the use of ruthenium(0) nanoclusters as catalyst in the hydrolysis of sodium borohydride liberating hydrogen gas. The ruthenium nanoparticles are generated from the reduction of ruthenium(III) chloride by sodium borohydride in water and stabilized by specific ligand. The ruthenium(0) nanoclusters are found to be highly active catalyst for the hydrolysis of sodium borohydride

Optimization of the cold trap design for the KASOLA sodium facility

International Nuclear Information System (INIS)

Onea, Alexandru; Lux, Martin; Hering, Wolfgang

2012-01-01

The KASOLA (KArlsruhe SOdium LAboratory) experimental facility is currently under construction at Karlsruhe Institute of Technology. The facility serves for research activities on thermal-hydraulics for liquid metal operated systems for transmutation (fast systems, normal operation, transient behaviour, testing of emergency cooling systems), accelerator target development, applications and development of free surface liquid metal targets for accelerators, as well as feasibility studies of liquid metals for solar applications. Supporting heat transfer studies regarding the development of turbulent liquid metal heat transfer models for CFD tools are also foreseen. In sodium operated facilities several impurities can be released during operation, e.g. argon, oxygen, hydrogen, carbon etc., with several adverse effects such as reducing the thermal performance and/or damaging structural materials. The major impurities monitored are sodium oxide Na 2 O and sodium hydride NaH. Hydrogen can diffuse through the steel pipes of the sodium-air heat exchanger or, in a worse case can be generated by a sodium-water reaction, denoting therefore a leak in the tubes of the heat exchanger. Oxygen may origin from the contact with air during maintenance or from the oxide layer of metallic structures initially exposed to sodium during set into operation procedures. The oxygen as an impurity leads to the corrosion of the steel surfaces, therefore values < 2 ppm have to be ensured, while for hydrogen the accepted amount is about 50 ppb (Hemanath et al.). The sodium purification is performed in a cold trap that allows the agglomeration of sodium oxide and sodium hydride on the large surface of a wire mesh. (orig.)

Exchange of deuterium with hydrogen of zeolite catalyst surface

International Nuclear Information System (INIS)

Minachev, Kh.M.; Dmitriev, R.V.; Penchev, V.; Kanazirev, V.; Minchev, Kh.; Kasimov, Ch.K.; Bylgarska Akademiya na Naukite, Sofia. Inst. za Obshta i Organichna Khimiya; AN Azerbajdzhanskoj SSR, Baku. Inst. Neftekhimicheskikh Protsessov)

1981-01-01

Isotope heteromolecular exchange of hydrogen on the reduced nickel-containing zeolites takes places at the temperatures above 100 deg and it is controlled by activated hydrogen transfer from metal particles on the substrate surface. High-temperature redox treatment of nickel-containing zeolites results in the formation of large nickel crystallites on zeolite external faces. The rest part of nickel remains in zeolite pores and conditions a high promoting effect in the exchange reaction. Catalytic activity of reduced zeolites NiCaNaY in toluene disproportionation increases considerably only in the cases when nickel is introduced into zeolite by means of ion exchange. Close spatial location of nickel particles and OH groups promotes the procedure of both isotope exchange and disproportionation of toluene [ru

Process for exchanging tritium between gaseous hydrogen and water

International Nuclear Information System (INIS)

Hindin, S.G.; Roberts, G.W.

1981-01-01

An improved method of exchanging and concentrating the radioactive isotope of hydrogen from water or hydrogen gas is described. This heavy water enrichment system involves a low pressure, dual temperature process. (U.K.)

Measurement of atomic-hydrogen spin-exchange parameters at 0.5 K using a cryogenic hydrogen maser

International Nuclear Information System (INIS)

Hayden, M.E.; Huerlimann, M.D.; Hardy, W.N.

1996-01-01

Using a cryogenic hydrogen maser, suitably modified to have electronic control of both the resonance frequency and the quality factor of the external cavity, we have measured a number of spin-exchange parameters for an atomic-hydrogen (H) gas at a temperature of 0.5 K. These results are relevant to the ultimate achievable frequency stability for cryogenic H masers and, when coupled with accurate calculations of the spin-exchange parameters, serve as a sensitive test of the H-H interatomic potentials. We find evidence for a frequency shift not predicted by semiclassical theories of spin exchange. In the context of a fully quantum mechanical hydrogen-atom spin-exchange theory [B. J. Verhaar et al., Phys. Rev. A 35, 3825 (1987) and J. M. V. A. Koelman et al., Phys. Rev. A 38, 3535 (1988)], this frequency shift is attributed to the influence of hyperfine interactions during spin-exchange collisions. Our findings are generally in agreement with these predictions; however, the sign of the hyperfine-induced frequency shift appears to differ from theory. copyright 1996 The American Physical Society

Coupling a PEM fuel cell and the hydrogen generation from aluminum waste cans

Energy Technology Data Exchange (ETDEWEB)

Martinez, Susana Silva; Albanil Sanchez, Loyda; Alvarez Gallegos, Alberto A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Mor. CP 62210 (Mexico); Sebastian, P.J. [Centro de Investigacion en Energia-UNAM, 62580 Temixco, Morelos (Mexico); Cuerpo Academico de Energia y Sustentabilidad, UPCH, Tuxtla Gutierrez, Chiapas (Mexico)

2007-10-15

High purity hydrogen was generated from the chemical reaction of aluminum and sodium hydroxide. The aluminum used in this study was obtained from empty soft drink cans and treated with concentrated sulfuric acid to remove the paint and plastic film. One gram of aluminum was reacted with a solution of 2moldm{sup -3} of sodium hydroxide to produce hydrogen. The hydrogen produced from aluminum cans and oxygen obtained from a proton exchange membrane electrolyzer or air, was fed to a proton exchange membrane (PEM) fuel cell to produce electricity. Yields of 44 mmol of hydrogen contained in a volume of 1.760dm{sup 3} were produced from one gram of aluminum in a time period of 20 min. (author)

Computational study of pristine and titanium-doped sodium alanates for hydrogen storage applications

Science.gov (United States)

Dathar, Gopi Krishna Phani

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained unanswered regarding the role of Ti in reversible hydrogen storage of sodium alanates with improved thermodynamics and kinetics of hydrogen desorption. The first question is about the position of transition metal dopants in the sodium aluminum hydride lattice. The position is investigated by identifying the possible sites for titanium dopants in NaAlH4 lattice and studying the structure and dynamics of possible compounds resulting from titanium doping in sodium alanates. The second question is the role of titanium dopants in improved thermodynamics of hydrogen desorption in Ti-doped NaAlH4. Though it is accepted in the literature that formation of TiAl alloys (Ti-Al and TiAl3) is favorable, reaction pathways are not clearly established. Furthermore, the source of aluminum for Ti-Al alloy formation is not clearly understood. The third question in this area is the role of titanium dopants in improved kinetics of hydrogen absorption and desorption in Ti-doped sodium alanates. This study is directed towards addressing the three longstanding questions in this area. Thermodynamic and kinetic pathways for hydrogen desorption in pristine NaAlH4 and formation of Ti-Al alloys in Ti-doped NaAlH 4, are elucidated to understand the underlying mechanisms of hydrogen desorption. Density functional theory

Inhibition of mitotic-specific histone phophorylation by sodium arsenite

Energy Technology Data Exchange (ETDEWEB)

Cobo, J.M. [Universidad de Alcala de Henares, Madrid (Spain); Valdez, J.G.; Gurley, L.R. [Los Alamos National Lab., NM (United States)

1994-10-01

Synchronized cultures of Chinese hamster cells (line CHO) were used to measure the effects of 10{mu}M sodium arsenite on histone phosphorylation. This treatment caused cell proliferation to be temporarily arrested, after which the cells spontaneously resumed cell proliferation in a radiomimetric manner. Immediately following treatment, it was found that sodium arsenite affected only mitotic-specific HI and H3 phosphorylations. Neither interphase, nor mitotic, H2A and H4 phosphorylations were affected, nor was interphase HI Phosphorylation affected. The phosphorylation of HI was inhibited only in mitosis, reducing HI phosphorylation to 38.1% of control levels, which was the level of interphase HI phosphorylation. The phosphorylation of both H3 variants was inhibited in mitosis, the less hydrophobic H3 to 19% and the more hydrophobic H3 to 24% of control levels. These results suggest that sodium arsenite may inhibite cell proliferation by interfering with the cyclin B/p34{sup cdc2} histone kinase activity which is thought to play a key role in regulating the cell cycle. It has been proposed by our laboratory that HI and H3 phosphorylations play a role in restructuring interphase chromatin into metaphase chromosomes. Interference of this process by sodium arsenite may lead to structurally damaged chromosomes resulting in the increased cancer risks known to be produced by arsenic exposure from the environment.

Hydrogen--deuterium exchanges in nucleosides and nucleotides. A mechanism for exchange of the exocyclic amino hydrogens of adenosine

International Nuclear Information System (INIS)

Cross, D.G.; Brown, A.; Fisher, H.F.

1975-01-01

The pH dependence of the apparent first-order rate constant for the exchange of the exocyclic amino hydrogens of adenosine with deuterium from the solvent was measured by stopped-flow ultraviolet spectroscopy. This dependence shows acid catalysis, base catalysis, and spontaneous exchange at neutral pH values. A study of the effect of several buffers on the rates of exchange reveals both general acid and general base catalytic behavior for the exchange process. We propose a general mechanism for the exchange which requires N-1 protonated adenosine as an intermediate for the acid-catalyzed exchange and amidine anion for the base-catalyzed exchange. In both cases the rate-limiting step is the base-catalyzed abstraction of a proton from the exocyclic amino moiety. Evaluation of the rate constants predicts the equilibrium for the exocyclic amino/imino tautomers to be 6.3 x 10 3 :1. (U.S.)

Water leak detection in sodium heated steam generators through measurement of hydrogen concentration in sodium

International Nuclear Information System (INIS)

Cambillard, E.; Lacroix, A.; Martin, P.; Viala, J.

1980-07-01

This report includes a description of apparatus for measuring hydrogen concentration in the secondary sodium system of the PHENIX reactor. The calibration method and results obtained since the commissioning of the reactor are also described. Mention is made of improvements to be built into SUPER PHENIX [fr

The various sodium purification techniques

International Nuclear Information System (INIS)

Courouau, J.L.; Masse, F.; Rodriguez, G.; Latge, C.; Redon, B.

1997-01-01

In the framework of sodium waste treatment, the sodium purification phase plays an essential role in the chain of operations leading to the transformation of the active sodium, considered as waste, into a stable sodium salt. The objectives of the purification operations are: To keep a low impurity level, particularly a low concentration in oxygen and hydrogen, in order to allow its transfer to a processing plant, and in order to avoid risks of plugging and/or corrosion in sodium facilities; To reduce the sodium activity in order to limit the dose rate close to the facilities, and in order to reduce the activity of the liquid and gaseous effluents. After a recall of the different kind of impurities that can be present in sodium, and of the different purification methods that could be associated with, the following points are highlighted: (i) Oxygen and hydrogen purification needs, and presentation of some selection criteria for a purification unit adapted to a sodium processing plant, as well as 2 cold trap concepts that are in accordance with these criteria: PSICHOS and PIRAMIDE. (ii) Tritium reduction in a bulk of liquid sodium by swamping, isotopic exchange, or permeation throughout a membrane. (iii) Caesium trapping on carbonaceous matrix. The main matrices used at present are R.V.C. (Reticulated Vitreous Carbon) and Actitex/Pica products. Tests in the laboratory and on an experimental device have demonstrated the performances of these materials, which are able to reduce sodium activity in Cs 134 and Cs 137 to very low values. The sodium purification processes as regards to the hydrogen, oxygen and caesium, that are aimed at facilitating the subsequent treatment of sodium, are therefore mastered operations. Regarding the operations associated with the reduction of the tritium activity, the methods are in the process of being qualified, or to be qualified. (author)

Sodium isotopic exchange rate between crystalline zirconium phosphate and molten NaNO/sub 3/

Energy Technology Data Exchange (ETDEWEB)

Inoue, Y; Yamada, Y [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1975-12-01

The isotopic exchange rate of sodium ion between crystalline zirconium phosphate and molten NaNO/sub 3/ has been measured at 312/sup 0/C and 362/sup 0/C by batch method. The equilibrium was reached within 20 minutes at either temperature, and the rate was very rapid as compared with that of sodium-potassium ion exchange.

Correlation between hydrogen release and degradation of limestone concrete exposed to hot liquid sodium in inert atmosphere

International Nuclear Information System (INIS)

Parida, F.C.; Das, S.K.; Sharma, A.K.; Ramesh, S.S.; Somayajulu, P.A.; Kannan, S.E.

2005-01-01

Full text of publication follows: Concrete is used as a structural material in a Fast Breeder Reactor (FBR) plant for the construction of its foundation, containment, radiation shield and equipment support structures. An accidental leakage of hot sodium on these civil structures can bring about thermo-chemical reactions, with concrete producing hydrogen gas and causing structural degradation. The concrete damage and hydrogen generation take place concurrently due to conduction of heat from sodium into the concrete and migration of steam / moisture in counter current direction towards sodium. In a series of experiments conducted with limestone concrete for two different types of design corresponding to composition and geometry, were exposed to liquid sodium (∼2 kg) at initial temperatures varying from 180 deg. C to 500 deg. C in an inerted test vessel (Capacity = 203 L). Immersion heater was employed to heat the sodium pool on the concrete cavity during the test period in some test runs. On-line continuous measurement of pressure, temperature, hydrogen gas and oxygen gas was carried out. Pre- and post- test nondestructive testing such as colour photography, spatial profiling of ultrasonic pulse velocity and measurement of dimensions were also conducted. Solid samples were collected from sodium debris by manual core drilling machine and from concrete block by hand held electric drilling machine. These samples were subjected to chemical analysis for the determination of free and bound water along with unburnt and burnt sodium. The hydrogen generation parameters such as average and peak release rate as well as release efficiency are derived from measured test variables. These test variables include temperature, pressure and hydrogen concentration in the argon atmosphere contained in the test vessel. The concrete degradation parameters encompass percentage reduction in ultrasonic pulse velocity, depth of physical and chemical dehydration and sodium penetration. These

Experimental determination of the phase diagram of the system sodium-sodium hydride up to 9000C and hydrogen pressures up to 800 bar

International Nuclear Information System (INIS)

Klostermeier, W.

1978-01-01

In the present work part of the sodium-sodium hydride system phase diagram has been studied at high temperatures (up to 900 0 C) and high hydrogen pressures (up to 1000 bar). The absorption isothermal curves recorded at temperatures between 650 0 C and 900 0 C show an increase in hydride solubility in sodium from 5.5 mol% at 650 0 to 19 mol% at 900 0 C. The melting point of sodium hydride has been measured giving the value 632 0 C with a hydrogen equilibrium pressure of 106 bar. In the mixing gap region the plateau equilibrium pressure, which is independent of composition, and his temperature dependence have been obtained. The enthalpy and entropy of melting are determined. (GSCH) [de

Process for hydrogen isotope exchange and concentration between liquid water and hydrogen gas and catalyst assembly therefor

International Nuclear Information System (INIS)

Stevens, W.H.

1975-01-01

A bithermal, catalytic, hydrogen isotope exchange process between liquid water and hydrogen gas to effect concentration of the deuterium isotope of hydrogen is described. Liquid water and hydrogen gas are contacted with one another and with at least one catalytically active metal selected from Group VIII of the Periodic Table; the catalyst body has a water repellent, gas and water vapor permeable, organic polymer or resin coating, preferably a fluorinated olefin polymer or silicone resin coating, so that the isotope exchange takes place by two simultaneously occurring, and closely coupled in space, steps and concentration is effected by operating two interconnected sections containing catalyst at different temperatures. (U.S.)

Thermal Decomposition of Sodium Hydrogen Carbonate and Textural Features of Its Calcines

Czech Academy of Sciences Publication Activity Database

Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Šyc, Michal

2013-01-01

Roč. 52, č. 31 (2013), s. 10619-10626 ISSN 0888-5885 R&D Projects: GA MŠk(CZ) 7C11009 Grant - others:RFCS(XE) RFCR-CT-2010-00009 Institutional support: RVO:67985858 Keywords : thermal decomposition * sodium hydrogen carbonate * sodium bicarbonate Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.235, year: 2013

Hydrogen permeation inhibition by zinc-nickel alloy plating on steel XC68

International Nuclear Information System (INIS)

El Hajjami, A.; Gigandet, M.P.; De Petris-Wery, M.; Catonne, J.C.; Duprat, J.J.; Thiery, L.; Raulin, F.; Starck, B.; Remy, P.

2008-01-01

The inhibition of hydrogen permeation and barrier effect by zinc-nickel plating was investigated using the Devanathan-Stachurski permeation technique. The hydrogen permeation and hydrogen diffusion for the zinc-nickel (12-15%) plating on steel XC68 is compared with zinc and nickel. Hydrogen permeation and hydrogen diffusion were followed as functions of time at current density applied (cathodic side) and potential permanent (anodic side). The hydrogen permeation inhibition for zinc-nickel is intermediate to that of nickel and zinc. This inhibition was due to nickel-rich layer effects at the Zn-Ni alloy/substrate interface, is shown by GDOES. Zinc-nickel plating inhibited the hydrogen diffusion greater as compared to zinc. This diffusion resistance was due to the barrier effect caused by the nickel which is present at the interface and transformed the hydrogen atomic to Ni 2 H compound, as shown by GIXRD.

Hydrogen permeation inhibition by zinc-nickel alloy plating on steel XC68

Energy Technology Data Exchange (ETDEWEB)

El Hajjami, A. [Institut UTINAM, UMR CNRS 6213, Sonochimie et Reactivite des Surfaces, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France); Coventya S.A.S., 51 rue Pierre, 92588 Clichy Cedex (France); Gigandet, M.P. [Institut UTINAM, UMR CNRS 6213, Sonochimie et Reactivite des Surfaces, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France)], E-mail: marie-pierre.gigandet@univ-fcomte.fr; De Petris-Wery, M. [Institut Universitaire de Technologie d' Orsay, Universite Paris XI, Plateau de Moulon, 91400 Orsay (France); Catonne, J.C. [Professeur Honoraire du Conservatoire national des arts et metiers (CNAM), Paris (France); Duprat, J.J.; Thiery, L.; Raulin, F. [Coventya S.A.S., 51 rue Pierre, 92588 Clichy Cedex (France); Starck, B.; Remy, P. [Lisi Automotive, 28 faubourg de Belfort, BP 19, 90101 Delle Cedex (France)

2008-12-30

The inhibition of hydrogen permeation and barrier effect by zinc-nickel plating was investigated using the Devanathan-Stachurski permeation technique. The hydrogen permeation and hydrogen diffusion for the zinc-nickel (12-15%) plating on steel XC68 is compared with zinc and nickel. Hydrogen permeation and hydrogen diffusion were followed as functions of time at current density applied (cathodic side) and potential permanent (anodic side). The hydrogen permeation inhibition for zinc-nickel is intermediate to that of nickel and zinc. This inhibition was due to nickel-rich layer effects at the Zn-Ni alloy/substrate interface, is shown by GDOES. Zinc-nickel plating inhibited the hydrogen diffusion greater as compared to zinc. This diffusion resistance was due to the barrier effect caused by the nickel which is present at the interface and transformed the hydrogen atomic to Ni{sub 2}H compound, as shown by GIXRD.

Mechanisms of hydrogen exchange in proteins from nuclear magnetic resonance studies of individual tryptophan indole NH hydrogens in lysozyme

International Nuclear Information System (INIS)

Wedin, R.E.; Delepierre, M.; Dobson, C.M.; Poulsen, F.M.

1982-01-01

The individual rates of solvent exchange of the six tryptophan indole NH hydrogens of lysozyme in 2 H 2 O have been measured over a wide range of temperatures by using 1 H NMR. Two distinct mechanisms for exchange have been identified, one characterized by a high activation energy and the other by a much lower activation energy. The high-energy process has been shown to be associated directly with the cooperative thermal unfolding of the protein and is the dominant mechanism for exchange of the most slowly exchanging hydrogen even 15 0 C below the denaturation temperature. Rate constants and activation energies for the folding and unfolding reactions were obtained from the experimental exchange rates. At low temperatures, a lower activation energy mechanism is dominant for all hydrogens, and this can be associated with local fluctuations in the protein structure which allow access of solvent. The relative exchange rates and activation energies can only qualitatively be related to the different environments of the residues in the crystal structure. There is provisional evidence that a mechanism intermediate between these two extremes may be significant for some hydrogens under restricted conditions

A Hydrogen Exchange Method Using Tritium and Sephadex: Its Application to Ribonuclease*

Science.gov (United States)

Englander, S. Walter

2012-01-01

A new method for measuring the hydrogen exchange of macromolecules in solution is described. The method uses tritium to trace the movement of hydrogen, and utilizes Sephadex columns to effect, in about 2 minutes, a separation between tritiated macromolecule and tritiated solvent great enough to allow the measurement of bound tritium. High sensitivity and freedom from artifact is demonstrated and the possible value of the technique for investigation of other kinds of colloid-small molecule interaction is indicated. Competition experiments involving tritium, hydrogen, and deuterium indicate the absence of any equilibrium isotope effect in the ribonuclease-hydrogen isotope system, though a secondary kinetic isotope effect is apparent when ribonuclease is largely deuterated. Ribonuclease shows four clearly distinguishable kinetic classes of exchangeable hydrogens. Evidence is marshaled to suggest the independently measurable classes II, III, and IV (in order of decreasing rate of exchange) to represent “random-chain” peptides, peptides involved in α-helix, and otherwise shielded side-chain and peptide hydrogens, respectively. PMID:14075117

Reactions of oxygen and hydrogen with liquid sodium - a critical survey

International Nuclear Information System (INIS)

Ullmann, H.

1982-01-01

The fundamentals of solvation chemistry are presented with appropriate components formulated. Methods of investigation and kinetics of the reactions are described. The hydrogen equilibrium pressure and saturation solubilities are described. The chemical equilibrium between O and H in solution is presented with detailed tabulation of the saturation solutions of oxygen, hydrogen and hydroxide in liquid sodium. Agreements and differences with the literature are presented

An optioneering and concept design study for the Astrid sodium-gas heat exchanger matrix

International Nuclear Information System (INIS)

Hattrell, T.; Lopez-Ramirez, S.; Pilatis, N.

2014-01-01

The ASTRID generation IV sodium cooled fast reactor design being developed by the CEA requires a component to transfer heat from the core to the power cycle. One of the ASTRID configurations currently being developed by the CEA uses a sodium to gas heat exchanger (SGHE) to fulfil this function. The design of the SGHE is challenging because of the high temperature of the sodium coolant and the significant pressure differential between the sodium and gas sides of the heat exchanger. This paper presents a study of the options examined for the ASTRID SGHE. A compact, superplastic formed diffusion bonded (SPF-DB) heat exchanger matrix (e.g. SGHE core) is proposed, based on the aerospace technology used by Rolls-Royce to manufacture light and strong wide chord fan blades for gas turbines. The in-house code CHESS is used to examine a number of feasible configurations for the matrix of the heat exchanger component and an optimisation study to maximise the thermal and mechanical performance of the most promising configurations is reported. The optimal matrix geometry identified by the study has a power density for the heat transfer region 157%1 greater than the baseline geometry (authors)

Study on influencing factors for hydrogen isotopic exchange

International Nuclear Information System (INIS)

Gu Mei; Liu Jun; Luo Yangming

2013-01-01

Background: Hydrogen-water catalytic exchange reaction offers an approach to hydrogen isotope separation, which can be applied in heavy water detritiation. Purpose: To optimize the operating condition for hydrogen-water catalytic exchange reaction, we analysed the influence of different factors on the transfer coefficient. Methods: In detail, the isotope exchange experiments of H-D system were carried out in a self-designed catalytic bed loaded with hydrophobic catalyst and hydrophilic packing with certain volume ratio. The experiments showed the changes of both the transfer coefficient and the pressure drop of column with the changing of the operational temperatures (29℃, 45℃, 60℃ and 75℃), the ratios of gas to liquid (0.58, 1.17, 2.65, 3.54) and the deuterium concentrations (5.05×10 -3 , 1.0144×10 -2 , 2.01×10 -2 ). Results: Results showed that 45℃ is the optimal temperature for operating. The transfer coefficient increases with the increasing of the ratio of gas to liquid in the ranges of 0.58 to 1.17 and 2.65 to 3.56, while decreases with the deuterium concentration increases from 5.05×10 -3 to 2.01×10 -2 . The pressure drop of column increases with increasing of gas flow rate. Conclusions: The experiment proves that the ratio of gas to liquid, the reaction temperature and the deuterium concentration are all important factors, which influence the transfer coefficient of deuterium obviously. The optimal operating condition for hydrogen-water catalytic exchange reaction are as follows: the temperature is 45℃, the ratio of gas to liquid is 3.56, and the deuterium concentration is 2.01×10 -2 . (authors)

Hydrogen-water isotopic exchange process

International Nuclear Information System (INIS)

Cheung, H.

1983-01-01

Deuterium is concentrated in a hydrogen-water isotopic exchange process enhanced by the use of catalyst materials in cold and hot tower contacting zones. Water is employed in a closed liquid recirculation loop that includes the cold tower, in which deuterium is concentrated in the water, and the upper portion of the hot tower in which said deuterium is concentrated in the hydrogen stream. Feed water is fed to the lower portion of said hot tower for contact with the circulating hydrogen stream. The feed water does not contact the water in the closed loop. Catalyst employed in the cold tower and the upper portion of the hot tower, preferably higher quality material, is isolated from impurities in the feed water that contacts only the catalyst, preferably of lower quality, in the lower portion of the hot zone. The closed loop water passes from the cold zone to the dehumidification zone, and a portion of said water leaving the upper portion of the hot tower can be passed to the humidification zone and thereafter recycled to said closed loop. Deuterium concentration is enhanced in said catalytic hydrogen-water system while undue retarding of catalyst activity is avoided

Hydrogen bonds of sodium alginate/Antarctic krill protein composite material.

Science.gov (United States)

Yang, Lijun; Guo, Jing; Yu, Yue; An, Qingda; Wang, Liyan; Li, Shenglin; Huang, Xuelin; Mu, Siyang; Qi, Shanwei

2016-05-20

Sodium alginate/Antarctic krill protein composite material (SA/AKP) was successfully obtained by blending method. The hydrogen bonds of SA/AKP composite material were analyzed by Fourier transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance hydrogen spectrum (HNMR). Experiment manifested the existence of intermolecular and intramolecular hydrogen bonds in SA/AKP system; strength of intermolecular hydrogen bond enhanced with the increase of AKP in the composite material and the interaction strength of hydrogen bonding followed the order: OH…Ether O>OH…π>OH…N. The percentage of intermolecular hydrogen bond decreased with increase of pH. At the same time, the effect of hydrogen bonds on properties of the composite material was discussed. The increase of intermolecular hydrogen bonding led to the decrease of crystallinity, increase of apparent viscosity and surface tension, as well as obvious decrease of heat resistance of SA/AKP composite material. SA/AKP fiber SEM images and energy spectrum showed that crystallized salt was separated from the fiber, which possibly led to the fibrillation of the composite fibers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of sodium borohydride synthesis on NaBH4-H2 system economics

International Nuclear Information System (INIS)

Tabakoglu, F. oeznur; Kurtulus, Guelbahar

2007-01-01

The hazards and negative impacts of fossil fuel usage on environment and the prospect of fossil fuel depletion in near future have urged scientists to search for and use clean energy sources and alternative fuels. Hydrogen is the best fuel among others, which can minimize the effects of global warming. Although it is currently more expensive than other fuels, it will be cheaper following further developments in hydrogen technologies from production till end-use. Hydrogen storage is a critical issue in terms of safety and economics of hydrogen energy system. Chemical hydrides are an attractive hydrogen storage method due to their potential of achieving high volumetric and gravimetric storage densities. Among chemical hydrides, sodium borohydride (NaBH 4 ) is given a big attention, due to its 10.8% theoretical hydrogen storage capacity. Hydrogen, which can be released by sodium borohydride hydrolysis reaction on-site, can be used in a proton exchange membrane fuel cell (PEMFC) at anode. on the other hand, sodium borohydride solution can be used directly in a borohydride fuel cell (DBFC) at anode. Like the other chemical hydrides, sodium borohydride has been an expensive material up to now, constituting a major obstacle to commercialization of sodium borohydride as a hydrogen storage method. This paper aims to give an approximate estimation process cost of the NaBH 4 -H 2 system by taking into account both the energy and raw material costs, starting with sodium borohydride production till recycling of it. Two different methods to synthesize sodium borohydride are analyzed and their effects on total cost are compared. It was found that the usage of Bayer process to synthesize sodium borohydride makes the overall sodium borohydride - hydrogen system cost higher than the total cost of the alternative process which starts with the production of sodium borohydride from borax decahydrate. (authors)

Empirical Correction for Differences in Chemical Exchange Rates in Hydrogen Exchange-Mass Spectrometry Measurements.

Science.gov (United States)

Toth, Ronald T; Mills, Brittney J; Joshi, Sangeeta B; Esfandiary, Reza; Bishop, Steven M; Middaugh, C Russell; Volkin, David B; Weis, David D

2017-09-05

A barrier to the use of hydrogen exchange-mass spectrometry (HX-MS) in many contexts, especially analytical characterization of various protein therapeutic candidates, is that differences in temperature, pH, ionic strength, buffering agent, or other additives can alter chemical exchange rates, making HX data gathered under differing solution conditions difficult to compare. Here, we present data demonstrating that HX chemical exchange rates can be substantially altered not only by the well-established variables of temperature and pH but also by additives including arginine, guanidine, methionine, and thiocyanate. To compensate for these additive effects, we have developed an empirical method to correct the hydrogen-exchange data for these differences. First, differences in chemical exchange rates are measured by use of an unstructured reporter peptide, YPI. An empirical chemical exchange correction factor, determined by use of the HX data from the reporter peptide, is then applied to the HX measurements obtained from a protein of interest under different solution conditions. We demonstrate that the correction is experimentally sound through simulation and in a proof-of-concept experiment using unstructured peptides under slow-exchange conditions (pD 4.5 at ambient temperature). To illustrate its utility, we applied the correction to HX-MS excipient screening data collected for a pharmaceutically relevant IgG4 mAb being characterized to determine the effects of different formulations on backbone dynamics.

Critical overview on water - hydrogen isotopic exchange; a case study

International Nuclear Information System (INIS)

Peculea, Marius

2002-01-01

Water - hydrogen isotopic exchange process is attractive due to its high separation factor; it is neither corrosive or pollutant and, when used as a technological process of heavy water production, it requires water as raw material. Its efficiency depends strongly on the catalyst performance and geometry of the isotopic water - hydrogen exchange zone in which the isotopic transfer proceeds in two steps: liquid vapor distillation in the presence of an inert gas and a catalytic reaction in vapor - gas gaseous phase. An overview of the water hydrogen isotopic exchange is presented and technological details of the Trail - Canada facility as well as characteristics of the two pilots operated in Romania with Ni, Cr and hydrophobic catalysts are described. The mathematical approach of the successive water-water vapor-hydrogen isotopic exchange process given is based on a mathematical model worked out earlier by Palibroda. Discrepancies between computation and experimental results, lower than 11% for extreme cases and around 6% for the average range are explained as due to the ratio of the exchange potentials. Assumption is made in the theoretical approach that this ratio is positive and constant all long the column while the measurements showed that it varies within 0.7 and 1.1 at the upper end and within - 2.5 and - 4.4 at the lower end, what indicates a strong end effect. In conclusion it is stressed that a competing technological solution is emerging based on a monothermal electrolytic process or a bithermal - bibaric process both for heavy water and tritium separation process

System design study of a membrane reforming hydrogen production plant using a small sized sodium cooled reactor

International Nuclear Information System (INIS)

Chikazawa, Y.; Konomura, M.; Hori, T.; Sato, H.; Uchida, S.

2004-01-01

In this study, a membrane reforming hydrogen production plant using a small sized sodium cooled reactor was designed as one of promising concepts. In the membrane reformer, methane and steam are reformed into carbon dioxide and hydrogen with sodium heat at a temperature 500 deg-C. In the equilibrium condition, steam reforming proceeds with catalyst at a temperature more than 800 deg-C. Using membrane reformers, the steam reforming temperature can be decreased from 800 to 500 deg-C because the hydrogen separation membrane removes hydrogen selectively from catalyst area and the partial pressure of hydrogen is kept much lower than equilibrium condition. In this study, a hydrogen and electric co-production plant has been designed. The reactor thermal output is 375 MW and 25% of the thermal output is used for hydrogen production (70000 Nm 3 /h). The hydrogen production cost is estimated to 21 yen/Nm 3 but it is still higher than the economical goal (17 yen/Nm 3 ). The major reason of the high cost comes from the large size of hydrogen separation reformers because of the limit of hydrogen separation efficiency of palladium membrane. A new highly efficient hydrogen separation membrane is needed to reduce the cost of hydrogen production using membrane reformers. There is possibility of multi-tube failure in the membrane reformers. In future study, a design of measures against tube failure and elemental experiments of reaction between sodium and reforming gas will be needed. (authors)

Contribution to the study of hydrogenated and oxygenated impurities in liquid sodium; Contribution a l'etude des impuretees hydrogenees et oxygenees dans le sodium liquide

Energy Technology Data Exchange (ETDEWEB)

Naud, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-15

This study is made up essentially of two parts. The first is devoted to the development of dosage methods for selectively determining the oxygenated and hydrogenated impurities present in sodium, that is the oxide, the hydride and the hydroxide. The second makes use of these methods for a study of the Na-H{sub 2}-O{sub 2} system, as well as of the related problem of the attack of pyrex glass by molten sodium. The conventional method for dosing oxygen by amalgamation was first adapted to the simultaneous measurement of the hydride. We then developed a method for dosing the total hydrogen by measuring successively the concentrations of gas present in the hydride and hydroxide form. This method is based on the thermal decomposition of the hydride and the reaction between sodium and the hydroxide. Our contribution to the study of the Na-H{sub 2}-O{sub 2} System consists first of all in the study of the reaction between hydrogen and sodium in the temperature range from 150 to 250 deg C and at a pressure of about 150 mm of mercury. The study of the thermal decomposition of the hydride in sodium was then studied. It was possible to make some qualitative observations concerning the reaction between sodium and sodium hydroxide. Finally some complementary tests made it possible to define the nature of the phenomena occurring during the attack of pyrex glass by sodium. (author) [French] Cette etude comporte essentiellement deux parties. La premiere est consacree a la mise au point de methodes de dosages permettant de determiner selectivement les impuretes oxygenees et hydrogenees presentes dans le sodium, a savoir l'oxyde, l'hydrure et l'hydroxyde. La seconde met a profit ces methodes en vue de l'etude du systeme Na-H{sub 2}-O{sub 2}. ainsi que du phenomene connexe d'attaque du verre pyrex par le sodium fondu. La methode classique de dosage de l'oxygene par amalgamation a d'abord ete adaptee au dosage simultane de l'hydrure. Nous avons ensuite mis au point le dosage de l'hydrogene

Inhibition of Sodium Benzoate on Stainless Steel in Tropical Seawater

International Nuclear Information System (INIS)

Seoh, S. Y.; Senin, H. B.; Nik, W. N. Wan; Amin, M. M.

2007-01-01

The inhibition of sodium benzoate for stainless steel controlling corrosion was studied in seawater at room temperature. Three sets of sample have been immersed in seawater containing sodium benzoate with the concentrations of 0.3M, 0.6M and 1.0M respectively. One set of sample has been immersed in seawater without adding any sodium benzoate. It was found that the highest corrosion rate was observed for the stainless steel with no inhibitor was added to the seawater. As the concentration of sodium benzoate being increased, the corrosion rate is decreases. Results show that by the addition of 1.0M of sodium benzoate in seawater samples, it giving ≥ 90% efficiencies

Hydrogen exchange kinetics changes upon formation of the soybean trypsin inhibitor: trypsin complex

International Nuclear Information System (INIS)

Woodward, C.K.; Ellis, L.M.

1975-01-01

The hydrogen exchange kinetics of the complex of trypsin--soybean trypsin inhibitor (Kunitz) have been compared to the calculated sum of the exchange kinetics for the inhibitor and trypsin measured separately. The exchange rates observed for the complex are substantially less than the sum of the exchange rates in the two individual proteins. These results cannot be accounted for by changes in intermolecular or intramolecular hydrogen bonding. The decrease in exchange rates in the complex are ascribed to changes in solvent accessibility in the component proteins. (U.S.)

Hydrogen exchange during cell-free incorporation of deuterated amino acids and an approach to its inhibition

Energy Technology Data Exchange (ETDEWEB)

Tonelli, Marco; Singarapu, Kiran K. [University of Wisconsin-Madison, National Magnetic Resonance Facility at Madison (NMRFAM), Department of Biochemistry (United States); Makino, Shin-ichi; Sahu, Sarata C.; Matsubara, Yuko [University of Wisconsin-Madison, Center for Eukaryotic Structural Genomics (CESG), Department of Biochemistry (United States); Endo, Yaeta [Ehime University, Cell-Free Science and Technology Research Center (Japan); Kainosho, Masatsune [Tokyo Metropolitan University, Center for Priority Areas (Japan); Markley, John L., E-mail: markley@nmrfam.wisc.edu [University of Wisconsin-Madison, National Magnetic Resonance Facility at Madison (NMRFAM), Department of Biochemistry (United States)

2011-12-15

Perdeuteration, selective deuteration, and stereo array isotope labeling (SAIL) are valuable strategies for NMR studies of larger proteins and membrane proteins. To minimize scrambling of the label, it is best to use cell-free methods to prepare selectively labeled proteins. However, when proteins are prepared from deuterated amino acids by cell-free translation in H{sub 2}O, exchange reactions can lead to contamination of {sup 2}H sites by {sup 1}H from the solvent. Examination of a sample of SAIL-chlorella ubiquitin prepared by Escherichia coli cell-free synthesis revealed that exchange had occurred at several residues (mainly at Gly, Ala, Asp, Asn, Glu, and Gln). We present results from a study aimed at identifying the exchanging sites and level of exchange and at testing a strategy for minimizing {sup 1}H contamination during wheat germ cell-free translation of proteins produced from deuterated amino acids by adding known inhibitors of transaminases (1 mM aminooxyacetic acid) and glutamate synthetase (0.1 mM l-methionine sulfoximine). By using a wheat germ cell-free expression system, we produced [U-{sup 2}H, {sup 15}N]-chlorella ubiquitin without and with added inhibitors, and [U-{sup 15}N]-chlorella ubiquitin as a reference to determine the extent of deuterium incorporation. We also prepared a sample of [U-{sup 13}C, {sup 15}N]-chlorella ubiquitin, for use in assigning the sites of exchange. The added inhibitors did not reduce the protein yield and were successful in blocking hydrogen exchange at C{sup {alpha}} sites, with the exception of Gly, and at C{sup {beta}} sites of Ala. We discovered, in addition, that partial exchange occurred with or without the inhibitors at certain side-chain methyl and methylene groups: Asn-H{sup {beta}}, Asp-H{sup {beta}}, Gln-H{sup {gamma}}, Glu-H{sup {gamma}}, and Lys-H{sup {epsilon}}. The side-chain labeling pattern, in particular the mixed chiral labeling resulting from partial exchange at certain sites, should be of

Volcano Plot for Bimetallic Catalysts in Hydrogen Generation by Hydrolysis of Sodium Borohydride

Science.gov (United States)

Koska, Anais; Toshikj, Nikola; Hoett, Sandra; Bernaud, Laurent; Demirci, Umit B.

2017-01-01

In the field of "hydrogen energy", sodium borohydride (NaBH[subscript 4]) is a potential hydrogen carrier able to release H[subscript 2] by hydrolysis in the presence of a metal catalyst. Our laboratory experiment focuses on this. It is intended for thirdyear undergraduate students in order to have hands-on laboratory experience through…

Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition.

Science.gov (United States)

Rajashekar, Yallappa; Shivanandappa, Thimmappa

2017-01-01

Decalesides are a new class of natural insecticides which are toxic to insects by contact via the tarsal gustatory chemosensilla. The symptoms of their toxicity to insects and the rapid knockdown effect suggest neurotoxic action, but the precise mode of action and the molecular targets for decaleside action are not known. We have presented experimental evidence for the involvement of sodium pump inhibition in the insecticidal action of decaleside in the cockroach and housefly. The knockdown effect of decaleside is concomitant with the in vivo inhibition of Na+, K+ -ATPase in the head and thorax. The lack of insecticidal action by experimental ablation of tarsi or blocking the tarsal sites with paraffin correlated with lack of inhibition of Na+- K+ ATPase in vivo. Maltotriose, a trisaccharide, partially rescued the toxic action of decaleside as well as inhibition of the enzyme, suggesting the possible involvement of gustatory sugar receptors. In vitro studies with crude insect enzyme preparation and purified porcine Na+, K+ -ATPase showed that decaleside competitively inhibited the enzyme involving the ATP binding site. Our study shows that the insecticidal action of decaleside via the tarsal gustatory sites is causally linked to the inhibition of sodium pump which represents a unique mode of action. The precise target(s) for decaleside in the tarsal chemosensilla and the pathway linked to inhibition of sodium pump and the insecticidal action remain to be understood.

SAIDE: A Semi-Automated Interface for Hydrogen/Deuterium Exchange Mass Spectrometry.

Science.gov (United States)

Villar, Maria T; Miller, Danny E; Fenton, Aron W; Artigues, Antonio

2010-01-01

Deuterium/hydrogen exchange in combination with mass spectrometry (DH MS) is a sensitive technique for detection of changes in protein conformation and dynamics. Since temperature, pH and timing control are the key elements for reliable and efficient measurement of hydrogen/deuterium content in proteins and peptides, we have developed a small, semiautomatic interface for deuterium exchange that interfaces the HPLC pumps with a mass spectrometer. This interface is relatively inexpensive to build, and provides efficient temperature and timing control in all stages of enzyme digestion, HPLC separation and mass analysis of the resulting peptides. We have tested this system with a series of standard tryptic peptides reconstituted in a solvent containing increasing concentration of deuterium. Our results demonstrate the use of this interface results in minimal loss of deuterium due to back exchange during HPLC desalting and separation. For peptides reconstituted in a buffer containing 100% deuterium, and assuming that all amide linkages have exchanged hydrogen with deuterium, the maximum loss of deuterium content is only 17% of the label, indicating the loss of only one deuterium molecule per peptide.

Hydrogen isotopic exchange reaction in a trickle-bed

International Nuclear Information System (INIS)

Paek, Seung Woo; Ahn, Do Hee; Kim, Kwang Rag; Lee, Min Soo; Yim, Sung Paal; Chung, Hong Suk

2005-01-01

The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is ideally suited for extracting tritium from water because of its high separation factor and mild operating conditions. This process for different hydrogen isotope applications has been developed by AECL. A laboratory scale CECE was built and operated at Mound Laboratory. Belgium and Japan have also developed independently similar processes which are based on a hydrophobic catalyst. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. The liquid phase catalytic exchange columns having various structures were developed; and it has been recognized that a multistage type and a trickle-bed type are promising. The multistage type gave more successful results than the trickle-bed type. However, the structure of the column is complicated. The trickle-bed type has a significant advantage in that the structure of the column is quite simple: the hydrophobic catalysts or the catalysts and packings are packed within the column. This structure would lead us to a smaller column height than the multistage type. This paper deals with the experiment for the hydrogen isotope exchange in a trickle-bed reactor packed with a hydrophobic catalyst and the design of the catalytic column for the CECE to tritium recovery from light water

Hydrogen isotopic exchange reaction in a trickle-bed

Energy Technology Data Exchange (ETDEWEB)

Paek, Seung Woo; Ahn, Do Hee; Kim, Kwang Rag; Lee, Min Soo; Yim, Sung Paal; Chung, Hong Suk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2005-07-01

The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is ideally suited for extracting tritium from water because of its high separation factor and mild operating conditions. This process for different hydrogen isotope applications has been developed by AECL. A laboratory scale CECE was built and operated at Mound Laboratory. Belgium and Japan have also developed independently similar processes which are based on a hydrophobic catalyst. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. The liquid phase catalytic exchange columns having various structures were developed; and it has been recognized that a multistage type and a trickle-bed type are promising. The multistage type gave more successful results than the trickle-bed type. However, the structure of the column is complicated. The trickle-bed type has a significant advantage in that the structure of the column is quite simple: the hydrophobic catalysts or the catalysts and packings are packed within the column. This structure would lead us to a smaller column height than the multistage type. This paper deals with the experiment for the hydrogen isotope exchange in a trickle-bed reactor packed with a hydrophobic catalyst and the design of the catalytic column for the CECE to tritium recovery from light water.

Isotopic exchange between molecular hydrogen and liquid ammonia catalysed by alkali amides; Echange isotopique entre l'hydrogene moleculaire et l'ammoniac liquide catalyse par les amidures alcalins

Energy Technology Data Exchange (ETDEWEB)

Delmas, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-06-15

The catalytic action of alkali amides on the isotopic exchange between hydrogen and liquid ammonia has been reinvestigated. It was clear before this work that the reaction is homogeneous and first order with respect to the concentration of dissolved hydrogen, but the nature of the catalytic species was still subject to discussion. On one hand new precise kinetic measurements have been made with sodium, potassium, rubidium and cesium amide. On the other hand, the dissociation of these salts has been calculated with the help of the FUOSS-ONSAGER equation. If the rate of exchange is plotted as a function of the concentration of the free amide ion, a linear relationship is obtained. In our experimental conditions, primary salt effects are negligible and the concentration has to be used in the rate equations. This shows that only the free amide ion is acting as a catalytic species. Experiments on common ion effects and secondary salt effects support this conclusion. The results are in agreement with an associative mechanism. (author) [French] Une nouvelle etude de l'echange isotopique entre l'hydrogene et l'ammoniac liquide catalyse par les amidures alcalins a ete effectuee. II etait bien etabli avant le present travail que la reaction etait homogene et que sa vitesse etait du premier ordre par rapport a la concentration d'hydrogene dissous, mais la nature de l'espece catalytique etait encore controversee. De nouvelles mesures cinetiques precises ont ete faites avec les amidures de sodium, de potassium, de rubidium et de cesium. D'autre part, la dissociation de ces sels a ete calculee a l'aide de l'equation de FUOSS-ONSAGER. On constate que la vitesse d'echange est proportionnelle a la concentration de l'ion amidure libre. Dans nos conditions experimentales, les effets de sel primaires sont negligeables, l'equation de vitesse doit s'exprimer simplement en fonction des concentrations. Ceci indique que l'ion amidure libre est la seule espece catalytique. Des experiences d

Heterogeneous Catalysis: Deuterium Exchange Reactions of Hydrogen and Methane

Science.gov (United States)

Mirich, Anne; Miller, Trisha Hoette; Klotz, Elsbeth; Mattson, Bruce

2015-01-01

Two gas phase deuterium/hydrogen exchange reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which gas mixtures can be passed and products collected for analysis. The first of these exchange reactions involves H[subscript 2] + D[subscript 2], which proceeds at temperatures as low as 77…

Substrate and product inhibition of hydrogen production by the extreme thermophile, Caldicellulosiruptor saccharolyticus

NARCIS (Netherlands)

Niel, van E.W.J.; Claassen, P.A.M.; Stams, A.J.M.

2003-01-01

Substrate and product inhibition of hydrogen production during sucrose fermentation by the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus was studied. The inhibition kinetics were analyzed with a noncompetitive, nonlinear inhibition model. Hydrogen was the most severe

Inhibition of hydrogen sulfide generation from disposed gypsum drywall using chemical inhibitors

Energy Technology Data Exchange (ETDEWEB)

Xu Qiyong [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); School of Environment and Energy, Shenzhen Graduate School of Peking University, 518055, (China); Townsend, Timothy, E-mail: ttown@ufl.edu [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); Bitton, Gabriel [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States)

2011-07-15

Disposal of gypsum drywall in landfills has been demonstrated to elevate hydrogen sulfide (H{sub 2}S) concentrations in landfill gas, a problem with respect to odor, worker safety, and deleterious effect on gas-to-energy systems. Since H{sub 2}S production in landfills results from biological activity, the concept of inhibiting H{sub 2}S production through the application of chemical agents to drywall during disposal was studied. Three possible inhibition agents - sodium molybdate (Na{sub 2}MoO{sub 4}), ferric chloride (FeCl{sub 3}), and hydrated lime (Ca(OH){sub 2}) - were evaluated using flask and column experiments. All three agents inhibited H{sub 2}S generation, with Na{sub 2}MoO{sub 4} reducing H{sub 2}S generation by interrupting the biological sulfate reduction process and Ca(OH){sub 2} providing an unfavorable pH for biological growth. Although FeCl{sub 3} was intended to provide an electron acceptor for a competing group of bacteria, the mechanism found responsible for inhibiting H{sub 2}S production in the column experiment was a reduction in pH. Application of both Na{sub 2}MoO{sub 4} and FeCl{sub 3} inhibited H{sub 2}S generation over a long period (over 180 days), but the impact of Ca(OH){sub 2} decreased with time as the alkalinity it contributed was neutralized by the generated H{sub 2}S. Practical application and potential environmental implications need additional exploration.

Design Evaluation of Thermal-hydraulic Test Facility for a Finned-tube Sodium-to-Air Heat Exchanger

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyungmo; Kim, Byeong-Yeon; Ko, Yung Joo; Cho, Youngil; Kim, Jong-Man; Son, Seok-Kwon; Jo, Youngchul; Kang, Byeong Su; Jung, Minhwan; Eoh, Jaehyuk; Lee, Hyeong-Yeon; Jeong, Ji-Young [KAERI, Daejeon (Korea, Republic of)

2016-05-15

This paper introduces the recent progress of overall design phase for the SELFA facility and deals with basic thermal-hydraulic design parameters and its design validation as well. For more reliable design of the safety-grade decay heat removal system (DHRS) in PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor), two kinds of sodium-to-air heat exchangers have been employed in the system as an ultimate heat sink. One is a natural draft sodium-to-air heat exchanger (AHX) with helically-coiled sodium tubes, and the other is a forced draft sodium-to-air heat exchanger (FHX) with finned tubes with a straight-type arranged. Since the FHX is normally operated in an active mode with a forced air draft conditions, its performance should be verified for any anticipated operating conditions. To validate the test section design, evaluations of both thermal-hydraulic and mechanical design have been carried out, and some new concepts or devices were newly employed to replicate the prototypic conditions as closely as possible.

Continuous analyzers of hydrogen and carbon in liquid sodium and of hydrocarbon total in protective atmosphere above sodium

International Nuclear Information System (INIS)

Pitak, O.; Fresl, M.

1980-01-01

The principle is described of a leak detector for detecting water penetration into sodium in a steam generator. The device operates as a diffusion H-meter with an ion pump. Ni or Fe diffusion diaphragm is washed with sodium while diffused hydrogen is pumped and also monitored with the ion pump. Another detector uses the principle of analyzing hydrocarbons in the cover gas above the sodium level. The carrier gas flow for the analyzer divided into measuring and reference parts is passed through a chamber housing the diffusion standard. For measuring carbon content in sodium, the detector analytical part may be completed with a chamber with moisturizing filling for scrubbing gas. Carbon passing through the diffusion Fe diaphragm is scrubbed on the inner wall in the form of CO which is reduced to methane and measured using the detector C-meter. (M.S.)

Aldosterone induction of electrogenic sodium transport in the apical membrane vesicles of rat distal colon

International Nuclear Information System (INIS)

Rajendran, V.M.; Kashgarian, M.; Binder, H.J.

1989-01-01

Na-H exchange is present in apical membrane vesicles (AMV) isolated from distal colon of normal rats. Because in intact tissue aldosterone both induces amiloride-sensitive electrogenic sodium transport and inhibits electroneutral sodium absorption, these studies with AMV were designed to establish the effect of aldosterone on sodium transport. An outward-directed proton gradient stimulated 22Na uptake in AMV isolated from distal colon of normal and dietary sodium depleted (with elevated aldosterone levels) experimental rats. Unlike normal AMV, proton gradient-dependent 22Na uptake in experimental AMV was inhibited when uptake was measured under voltage-clamped conditions. 10 microM amiloride inhibited the initial rate of proton gradient-dependent 22Na uptake in AMV of normal and experimental rats by 30 and 75%, respectively. In contrast, 1 mM amiloride produced comparable inhibition (90 and 80%) of 22Na uptake in normal and experimental AMV. Intravesicular-negative potential stimulated 22Na uptake in experimental but not in normal AMV. This increase was inhibited by 90% by 10 microM amiloride. An analogue of amiloride, 5-(N-ethylisopropyl) amiloride (1 microM), a potent inhibitor of electroneutral Na-H exchange in AMV of normal rat distal colon, did not alter potassium diffusion potential-dependent 22Na uptake. Increasing sodium concentration saturated proton gradient-dependent 22Na uptake in normal AMV. However, in experimental AMV, 22Na uptake stimulated by both proton gradient and potassium diffusion potential did not saturate as a function of increasing sodium concentration. We conclude from these results that an electrically sensitive conductive channel, not electroneutral Na-H exchange, mediates 22Na uptake in AMV isolated from the distal colon of aldosterone rats

Role of sodium hydroxide in the production of hydrogen gas from the hydrothermal gasification of biomass

Energy Technology Data Exchange (ETDEWEB)

Onwudili, Jude A.; Williams, Paul T. [Energy and Resources Research Institute, University of Leeds, Leeds, LS2 9JT (United Kingdom)

2009-07-15

The role of sodium hydroxide as a promoter of hydrogen gas production during the hydrothermal gasification of glucose and other biomass samples has been investigated. Experiments were carried out in a batch reactor with glucose and also in the presence of the alkali from 200 C, 2 MPa to 450 C, 34 MPa at constant water loading. Without sodium hydroxide, glucose decomposed to produce mainly carbon dioxide, water, char and tar. Furfural, its derivatives and reaction products dominated the ethyl acetate extract of the water (organic fraction) at lower reaction conditions. This indicated that the dehydration of glucose to yield these products was unfavourable to hydrogen gas production. In the presence of sodium hydroxide however, glucose initially decomposed to form mostly alkylated and hydroxylated carbonyl compounds, whose further decomposition yielded hydrogen gas. It was observed that at 350 C, 21.5 MPa, half of the optimum hydrogen gas yield had formed and at 450 C, 34 MPa, more than 80 volume percent of the gaseous effluent was hydrogen gas, while the balance was hydrocarbon gases, mostly methane ({>=}10 volume percent). Other biomass samples were also comparably reacted at the optimum conditions observed for glucose. The rate of hydrogen production for the biomass samples was in the following order; glucose > cellulose, starch, rice straw > potato > rice husk. (author)

Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition.

Directory of Open Access Journals (Sweden)

Yallappa Rajashekar

Full Text Available Decalesides are a new class of natural insecticides which are toxic to insects by contact via the tarsal gustatory chemosensilla. The symptoms of their toxicity to insects and the rapid knockdown effect suggest neurotoxic action, but the precise mode of action and the molecular targets for decaleside action are not known. We have presented experimental evidence for the involvement of sodium pump inhibition in the insecticidal action of decaleside in the cockroach and housefly. The knockdown effect of decaleside is concomitant with the in vivo inhibition of Na+, K+ -ATPase in the head and thorax. The lack of insecticidal action by experimental ablation of tarsi or blocking the tarsal sites with paraffin correlated with lack of inhibition of Na+- K+ ATPase in vivo. Maltotriose, a trisaccharide, partially rescued the toxic action of decaleside as well as inhibition of the enzyme, suggesting the possible involvement of gustatory sugar receptors. In vitro studies with crude insect enzyme preparation and purified porcine Na+, K+ -ATPase showed that decaleside competitively inhibited the enzyme involving the ATP binding site. Our study shows that the insecticidal action of decaleside via the tarsal gustatory sites is causally linked to the inhibition of sodium pump which represents a unique mode of action. The precise target(s for decaleside in the tarsal chemosensilla and the pathway linked to inhibition of sodium pump and the insecticidal action remain to be understood.

Minimizing Back Exchange in the Hydrogen Exchange-Mass Spectrometry Experiment

Science.gov (United States)

Walters, Benjamin T.; Ricciuti, Alec; Mayne, Leland; Englander, S. Walter

2012-12-01

The addition of mass spectrometry (MS) analysis to the hydrogen exchange (HX) proteolytic fragmentation experiment extends powerful HX methodology to the study of large biologically important proteins. A persistent problem is the degradation of HX information due to back exchange of deuterium label during the fragmentation-separation process needed to prepare samples for MS measurement. This paper reports a systematic analysis of the factors that influence back exchange (solution pH, ionic strength, desolvation temperature, LC column interaction, flow rates, system volume). The many peptides exhibit a range of back exchange due to intrinsic amino acid HX rate differences. Accordingly, large back exchange leads to large variability in D-recovery from one residue to another as well as one peptide to another that cannot be corrected for by reference to any single peptide-level measurement. The usual effort to limit back exchange by limiting LC time provides little gain. Shortening the LC elution gradient by 3-fold only reduced back exchange by ~2 %, while sacrificing S/N and peptide count. An unexpected dependence of back exchange on ionic strength as well as pH suggests a strategy in which solution conditions are changed during sample preparation. Higher salt should be used in the first stage of sample preparation (proteolysis and trapping) and lower salt (<20 mM) and pH in the second stage before electrospray injection. Adjustment of these and other factors together with recent advances in peptide fragment detection yields hundreds of peptide fragments with D-label recovery of 90 % ± 5 %.

Minimizing back exchange in the hydrogen exchange-mass spectrometry experiment.

Science.gov (United States)

Walters, Benjamin T; Ricciuti, Alec; Mayne, Leland; Englander, S Walter

2012-12-01

The addition of mass spectrometry (MS) analysis to the hydrogen exchange (HX) proteolytic fragmentation experiment extends powerful HX methodology to the study of large biologically important proteins. A persistent problem is the degradation of HX information due to back exchange of deuterium label during the fragmentation-separation process needed to prepare samples for MS measurement. This paper reports a systematic analysis of the factors that influence back exchange (solution pH, ionic strength, desolvation temperature, LC column interaction, flow rates, system volume). The many peptides exhibit a range of back exchange due to intrinsic amino acid HX rate differences. Accordingly, large back exchange leads to large variability in D-recovery from one residue to another as well as one peptide to another that cannot be corrected for by reference to any single peptide-level measurement. The usual effort to limit back exchange by limiting LC time provides little gain. Shortening the LC elution gradient by 3-fold only reduced back exchange by ~2%, while sacrificing S/N and peptide count. An unexpected dependence of back exchange on ionic strength as well as pH suggests a strategy in which solution conditions are changed during sample preparation. Higher salt should be used in the first stage of sample preparation (proteolysis and trapping) and lower salt (<20 mM) and pH in the second stage before electrospray injection. Adjustment of these and other factors together with recent advances in peptide fragment detection yields hundreds of peptide fragments with D-label recovery of 90% ± 5%.

Preparation of Pt-PTFE hydrophobic catalyst for hydrogen-water isotope exchange

International Nuclear Information System (INIS)

Li Junhua; Kang Yi; Han Yande; Ruan Hao; Dou Qincheng; Hu Shilin

2001-01-01

The hydrophobic catalyst used in the hydrogen-water isotope exchange is prepared with Pt as the active metal, PTFE as the hydrophobic material, active carbon or silicon dioxide as the support. The isotope catalytic exchange reaction between hydrogen and water is carried out in the trickle bed and the effects of different carriers, mass fraction of Pt and PTFE on the catalytic activity are discussed. The experimental results show that the activity of Pt-C-PTFE hydrophobic catalyst with the ratio between PTFE and Pt-C from 1 to 2 is higher than other kinds of catalysts and the overall volume transfer coefficient is increased with the increasing of the hydrogen flow rate and reaction temperature

Clinical findings and effect of sodium hydrogen carbonate in patients with glutathione synthetase deficiency.

Science.gov (United States)

Gündüz, Mehmet; Ünal, Özlem; Kavurt, Sumru; Türk, Emrecan; Mungan, Neslihan Önenli

2016-04-01

Glutathione synthetase (GS) deficiency is a rare inborn error of glutathione (GSH) metabolism manifested by severe metabolic acidosis, hemolytic anemia, neurological problems and massive excretion of pyroglutamic acid (5-oxoproline) in the urine. The disorder has mild, moderate, and severe clinical variants. We aimed to report clinical and laboratory findings of four patients, effect of sodium hydrogen carbonate treatment and long-term follow up of three patients. Urine organic acid analysis was performed with gas chromatography-mass spectrometry. Molecular genetic analysis was performed in three patients, mutation was found in two of them. Enzyme analysis was performed in one patient. Clinical and laboratory findings of four patients were evaluated. One patient died at 4 months old, one patient's growth and development are normal, two patients have developed intellectual disability and seizures in the long term follow up period. Three patients benefited from sodium hydrogen carbonate treatment. The clinical picture varies from patient to patient, so it is difficult to predict the prognosis and the effectiveness of treatment protocols. We reported long term follow up of four patients and demonstrated that sodium hydrogen carbonate is effective for treatment of chronic metabolic acidosis in GS deficieny.

Inhibition of phospholipase A2 from human plasma by sodium bisulfite

International Nuclear Information System (INIS)

Wiggins, C.W.; Franson, R.C.

1987-01-01

The anti-oxidant sodium bisulfite has been shown to inhibit acid active(lysosomal), non-Ca ++ -dependent phospholipase A 2 (PLA 2 ), and to interact reversibly with unsaturated fatty acids, altering their chromatographic mobility. The authors examined the effect of bisulfite on neutral active, Ca ++ -dependent PLA 2 from human plasma. Using [1- 14 C]oleate-labelled autoclaved E. coli as substrate, PLA 2 activity was inhibited in a dose-dependent manner by bisulfite. Maximal inhibition occurred at 100μM bisulfite. Preincubation of plasma for 0-30 minutes with bisulfite resulted in a time-dependent increase in PLA 2 inhibition. Preincubation of substrate with bisulfite had no such effect. When the plasma PLA 2 was purified 25-fold by SP-Sephadex chromatography it was no longer inhibited by bisulfite. The SP-Sephadex wash through fraction, which contained greater than 95% of the applied protein but not PLA 2 activity, did not inhibit the purified enzyme. When incubated with bisulfite however, the SP-wash through fraction produced dose-dependent inhibition of the purified enzyme. These results indicate that sodium bisulfite inhibits human plasma PLA 2 , in vitro, indirectly by interaction with a factor(s) present in plasma and suggests that anti-oxidants may similarly influence expression of extracellular PLA 2 in vivo

Action of neuro-hypophysis hormones on sodium exchanges of Carassius auratus L

International Nuclear Information System (INIS)

Julien, Monique

1960-01-01

This academic work reports the use of radio-sodium as indicator of sodium exchanges to simultaneously measure the gill input flow and the output gill and urinary flows. This technique has been applied in the case of a common soft water fish (Carassius auratus L.) to study the possible action of neuro-hypophysis extracts on these flows, and the action of these hormones on urinary excretion [fr

Assessing the Sodium Exchange Capacity in Rainfed and Irrigated Soils in the Mediterranean Basin Using GIS

Directory of Open Access Journals (Sweden)

Luís Loures

2017-03-01

Full Text Available The soil exchange complex consists of colloidal materials on which ion exchange phenomena occur allowing it to attract, retain, and exchange elements that have opposite electric charges. Since their mineral constituents (clay and organic components (humus are mainly of a negative nature retained or exchanged ion are predominantly cations. Historically, failing to monitor parameters like the exchange sodium percentage (ESP has led to the permanent deterioration of soils which have become completely unproductive, largely reducing the sustainability of the agricultural systems. This study assesses how the sodium exchange capacity in irrigated soils differs from the rainfed ones through a sample survey that was carried out in the 15,031 ha of the Caia Irrigation Perimeter and adjacent areas, located in the municipalities of Elvas and Campo Maior, Portalegre District, Portugal where 14,280 georeferenced samples were collected from the top soil layer (0–20 cm, which were mixed 10 at a time so that each composite sample representing 11.1 ha. Then the samples were analyzed regarding the most relevant parameters for characterizing the soil exchange complex including the concentrations of exchanged bases and Cation Exchange Capacity (CEC. The results were arranged in a georeferenced grid with 1451 entries. Using classical statistical analysis and Geographic Information Systems (GIS software, it was possible to relate the individual soil samples analyzed with the cultural system practiced (irrigated or rainfed and the present soil group which permitted us to analyze the influence of the cultural system in the soil exchange complex. The distribution chart of the exchange sodium and CEC were created. The obtained results confirm a general decrease of CEC values and an increase of the exchangeable sodium content of irrigated explored soils when compared to the rainfed ones, putting forward noteworthy ideas not only regarding the necessary changes towards

Ion-exchange properties of cesium and strontium into zeolites from sodium salt solutions

International Nuclear Information System (INIS)

Kanno, Takuji; Hashimoto, Hiroyuki; Ohtani, Tozo.

1978-01-01

The ion-exchange properties of cesium and strontium into zeolite from sodium salt solution has been studied in zeolite A, zeolite X, zeolite Y, mordenite and clinoptilolite. The distribution of cesium into mordenite from about 1 -- 2 M sodium chloride and sodium hydroxide solutions is considerably larger than that into zeolite A. The distribution coefficient for 2 M solution of sodium salts was about 300. Therefore, the separation of cesium from sodium salt solution is possible by using mordenite. The distribution of strontium into zeolites form 1 -- 2 M solutions of sodium chloride and sodium nitrate were in the order of zeolite A>zeolite X>zeolite Y asymptoticaly equals mordenite. The distribution coefficient of 230 was obtained for 1 M solutions of sodium salts. The anion in solutions had no effect on the distribution of cesium and strontium into zeolite from sodium salt solution. (author)

Performance characterization of hydrogen isotope exchange and recombination catalysts for tritium processing

International Nuclear Information System (INIS)

Suppiah, S.; Ryland, D.; Marcinkowska, K.; Boniface, H.; Everatt, A.

2010-01-01

AECL's hydrogen isotope exchange catalyst and recombination catalysts have been successfully applied to a wide range of industrial tritium-removal applications. The catalysts are used for Liquid Phase Catalytic Exchange (LPCE) and for gas-phase and trickle-bed recombination of hydrogen isotopes and have led to process simplification, improved safety and operational advantages. Catalyst performance design equations derived from laboratory testing of these catalysts have been validated against performance under industrial conditions. In a Combined Electrolysis and Catalytic Exchange (CECE) demonstration plant analyses of LPCE and recombiner efficiency were carried out as a function of catalyst activity over a wide range of operation. A steady-state process simulation used to model and design the hydrogen-water isotopic exchange processes, such as the CECE detritiation plant, was validated using the results of this demonstration. Catalyst development for isotope-exchange and recombination applications has continued over the last decade. As a result, significant improvements in catalyst performance have been achieved for these applications. This paper outlines the uniqueness of AECL's specialized catalysts and process designs for these applications with examples from laboratory and industrial case studies.

NMR Analysis of Amide Hydrogen Exchange Rates in a Pentapeptide-Repeat Protein from A. thaliana.

Science.gov (United States)

Xu, Shenyuan; Ni, Shuisong; Kennedy, Michael A

2017-05-23

At2g44920 from Arabidopsis thaliana is a pentapeptide-repeat protein (PRP) composed of 25 repeats capped by N- and C-terminal α-helices. PRP structures are dominated by four-sided right-handed β-helices typically consisting of mixtures of type II and type IV β-turns. PRPs adopt repeated five-residue (Rfr) folds with an Rfr consensus sequence (STAV)(D/N)(L/F)(S/T/R)(X). Unlike other PRPs, At2g44920 consists exclusively of type II β-turns. At2g44920 is predicted to be located in the thylakoid lumen although its biochemical function remains unknown. Given its unusual structure, we investigated the biophysical properties of At2g44920 as a representative of the β-helix family to determine if it had exceptional global stability, backbone dynamics, or amide hydrogen exchange rates. Circular dichroism measurements yielded a melting point of 62.8°C, indicating unexceptional global thermal stability. Nuclear spin relaxation measurements indicated that the Rfr-fold core was rigid with order parameters ranging from 0.7 to 0.9. At2g44920 exhibited a striking range of amide hydrogen exchange rates spanning 10 orders of magnitude, with lifetimes ranging from minutes to several months. A weak correlation was found among hydrogen exchange rates, hydrogen bonding energies, and amino acid solvent-accessible areas. Analysis of contributions from fast (approximately picosecond to nanosecond) backbone dynamics to amide hydrogen exchange rates revealed that the average order parameter of amides undergoing fast exchange was significantly smaller compared to those undergoing slow exchange. Importantly, the activation energies for amide hydrogen exchange were found to be generally higher for the slowest exchanging amides in the central Rfr coil and decreased toward the terminal coils. This could be explained by assuming that the concerted motions of two preceding or following coils required for hydrogen bond disruption and amide hydrogen exchange have a higher activation energy

Potassium/sodium ion exchange of sodium aluminosilicate and soda-lime glasses with potassium nitrate melts

International Nuclear Information System (INIS)

Richter, E.

1983-08-01

The alkali self-diffusion coefficients, the concentration-dependent interdiffusion coefficients, and the actual equilibrium constants of the ion exchange process were determinated for model glasses of the Na 2 O-Al 2 O 3 -SiO 2 type and the Na 2 O-CaO-SiO 2 type by nuclear techniques. The measured self-diffusion data and interdiffusion coefficients were used to estimate the stress profiles initiated by the K/Na exchange below the transformation temperature in the surface region. The activation volume of the sodium and potassium ions for diffusion through the surface zone stressed by ion exchange was determined. The disturbing influence of small concentrations of determined divalent cations in KNO 3 (especially Ca 2+ ) was investigated and thermodynamically described. Possibilities were demonstrated to remove these disturbances by anionic admixtures to the KNO 3 melt. Conclusions were drawn for the technical process of the chemical strengthening of glass by K/Na ion exchange at lower temperatures. (author)

1 kWe sodium borohydride hydrogen generation system Part II: Reactor modeling

OpenAIRE

Zhang, Jinsong; Zheng, Yuan; Gore, Jay P; Mudawar, Issam; Fisher, Timothy

2007-01-01

Sodium borohydride (NaBH4) hydrogen storage systems offer many advantages for hydrogen storage applications. The physical processes inside a NaBH4 packed bed reactor involve multi-component and multi-phase flow and multi-mode heat and mass transfer. These processes are also coupled with reaction kinetics. To guide reactor design and optimization, a reactor model involving all of these processes is desired. A onedimensional numerical model in conjunction with the assumption of homogeneous cata...

Catalytic heat exchangers for small-scale production of hydrogen - feasibility study

Energy Technology Data Exchange (ETDEWEB)

Silversand, F [Catator AB, Lund (Sweden)

2002-02-01

A feasibility study concerning heat-exchanger reactors in small-scale production of hydrogen has been performed on the request of Svenskt Gastekniskt Center AB and SWEP International AB. The basic idea is to implement different catalysts into brazed plate-type heat exchangers. This can be achieved by installing catalytic cylinders in the inlet-and outlet ports of the heat exchangers or through treatment of the plates to render them catalytically active. It is also possible to sandwich catalytically active wire meshes between the plates. Experiments concerning steam reforming of methanol and methane have been performed in a micro-reactor to gather kinetic data for modelling purposes. Performance calculations concerning heat exchanger reactors have then been conducted with Catator's generic simulation code for catalytic reactors (CatalystExplorer). The simulations clearly demonstrate the technical performance of these reactors. Indeed, the production rate of hydrogen is expected to be about 10 nm{sup 3}/h per litre of heat exchanger. The corresponding value for a conventional steam-reforming unit is about 1 nm{sup 3}/h or less per litre of reactor volume. Also, the compactness and the high degree of integration together with the possibilities of mass production will give an attractive cost for such units. Depending on the demands concerning the purity of the hydrogen it is possible to add secondary catalytic steps like water-gas shifters, methanation and selective oxidation, into a one-train unit, i.e. to design an all-inclusive design. Such reactors can be used for the supply of hydrogen to fuel cells. The production cost for hydrogen can be cut by 60 - 70% through the utilisation of heat exchanger reactors instead of conventional electrolysis. This result is primarily a result of the high price for electricity compared to the feed stock prices in steam reforming. It is important to verify the performance calculations and the simulation results through experimental

Catalytic heat exchangers for small-scale production of hydrogen - feasibility study

Energy Technology Data Exchange (ETDEWEB)

Silversand, F. [Catator AB, Lund (Sweden)

2002-02-01

A feasibility study concerning heat-exchanger reactors in small-scale production of hydrogen has been performed on the request of Svenskt Gastekniskt Center AB and SWEP International AB. The basic idea is to implement different catalysts into brazed plate-type heat exchangers. This can be achieved by installing catalytic cylinders in the inlet-and outlet ports of the heat exchangers or through treatment of the plates to render them catalytically active. It is also possible to sandwich catalytically active wire meshes between the plates. Experiments concerning steam reforming of methanol and methane have been performed in a micro-reactor to gather kinetic data for modelling purposes. Performance calculations concerning heat exchanger reactors have then been conducted with Catator's generic simulation code for catalytic reactors (CatalystExplorer). The simulations clearly demonstrate the technical performance of these reactors. Indeed, the production rate of hydrogen is expected to be about 10 nm{sup 3}/h per litre of heat exchanger. The corresponding value for a conventional steam-reforming unit is about 1 nm{sup 3}/h or less per litre of reactor volume. Also, the compactness and the high degree of integration together with the possibilities of mass production will give an attractive cost for such units. Depending on the demands concerning the purity of the hydrogen it is possible to add secondary catalytic steps like water-gas shifters, methanation and selective oxidation, into a one-train unit, i.e. to design an all-inclusive design. Such reactors can be used for the supply of hydrogen to fuel cells. The production cost for hydrogen can be cut by 60 - 70% through the utilisation of heat exchanger reactors instead of conventional electrolysis. This result is primarily a result of the high price for electricity compared to the feed stock prices in steam reforming. It is important to verify the performance calculations and the simulation results through

Shifts in metabolic hydrogen sinks in the methanogenesis-inhibited ruminal fermentation: a meta-analysis

Directory of Open Access Journals (Sweden)

Emilio M. Ungerfeld

2015-02-01

Full Text Available Maximizing the flow of metabolic hydrogen ([H] in the rumen away from CH4 and towards volatile fatty acids (VFA would increase the efficiency of ruminant production and decrease its environmental impact. The objectives of this meta-analysis were: i To quantify shifts in metabolic hydrogen sinks when inhibiting ruminal methanogenesis in vitro; and ii To understand the variation in shifts of metabolic hydrogen sinks among experiments and between batch and continuous cultures systems when methanogenesis is inhibited. Batch (28 experiments, N=193 and continuous (16 experiments, N=79 culture databases of experiments with at least 50% inhibition in CH4 production were compiled. Inhibiting methanogenesis generally resulted in less fermentation and digestion in most batch culture, but not in most continuous culture, experiments. Inhibiting CH4 production in batch cultures resulted in redirection of metabolic hydrogen towards propionate and H2 but not butyrate. In continuous cultures, there was no overall metabolic hydrogen redirection towards propionate or butyrate, and H2 as a proportion of metabolic hydrogen spared from CH4 production was numerically smaller compared to batch cultures. Dihydrogen accumulation was affected by type of substrate and methanogenesis inhibitor, with highly fermentable substrates resulting in greater redirection of metabolic hydrogen towards H2 when inhibiting methanogenesis, and some oils causing small or no H2 accumulation. In both batch and continuous culture, there was a decrease in metabolic hydrogen recovered as the sum of propionate, butyrate, CH4 and H2 when inhibiting methanogenesis, and it is speculated that as CH4 production decreases metabolic hydrogen could be increasingly incorporated into formate, microbial biomass, and, perhaps, reductive acetogenesis in continuous cultures. Energetic benefits of inhibiting methanogenesis depended on the inhibitor and its concentration and on the in vitro system.

Hydrogen-water deuterium exchange over metal oxide promoted nickel catalysts

Energy Technology Data Exchange (ETDEWEB)

Sagert, N H; Shaw-Wood, P E; Pouteau, R M.L. [Atomic Energy of Canada Ltd., Pinawa, Manitoba. Whiteshell Nuclear Research Establishment

1975-11-01

Specific rates have been measured for hydrogen-water deuterium isotope exchange over unsupported nickel promoted with about 20% of various metal oxides. The oxides used were Cr/sub 2/O/sub 3/, MoO/sub 2/, MnO, WO/sub 2/-WO/sub 3/, and UO/sub 2/. Nickel surface areas, which are required to measure the specific rates, were determined by hydrogen chemisorption. Specific rates were measured as a function of temperature in the range 353 to 573 K and as a function of the partial pressure of hydrogen and water over a 10-fold range of partial pressure. The molybdenum and tungsten oxides gave the highest specific rates, and manganese and uranium oxides the lowest. Chromium oxide was intermediate, although it gave the highest rate per gram of catalyst. The orders with respect to hydrogen and water over molybdenum oxide and tungsten oxide promoted nickel were consistent with a mechanism in which nickel oxide is formed from the reaction of water with the catalyst, and then is reduced by hydrogen. Over manganese and uranium oxide promoted catalysts, these orders are consistent with a mechanism in which adsorbed water exchanges with chemisorbed hydrogen atoms on the nickel surface. Chromium oxide is intermediate. It was noted that those oxides which favored the nickel oxide route had electronic work functions closest to those of metallic nickel and nickel oxide.

Geographic distribution of soluble salts, exchangeable sodium and calcium carbonate in the Caribbean Region of Colombia

International Nuclear Information System (INIS)

Pulido, Carlos E

2000-01-01

A research was carried out to establish the distribution of soluble salts, exchangeable sodium and calcium carbonate in the soils of the Caribbean Region. The results show that 28,3% (3.506.033 ha) of the soils have problems related to salinity. The soils of the arid and semiarid zones and those belonging to the sea plain are affected severely by soluble salts, exchangeable sodium and calcium carbonate

τ - hydrogen phosphate of zirconia in sodium salt form and some of its properties

International Nuclear Information System (INIS)

Fernandez V, S.M.; Ordonez R, E.

2004-01-01

It is reported the obtaining and characterization in the sodium salt form of the τ-hydrogen phosphate of zirconium in sodium form, this compound it was synthesized, for a new technique developed in the laboratory of Dept. of Chemistry of the ININ. The characterization was carried out for XRD, IR, Sem and EDS the thermal gravimetric analysis is also reported. (Author)

Impurity profiling of liothyronine sodium by means of reversed phase HPLC, high resolution mass spectrometry, on-line H/D exchange and UV/Vis absorption.

Science.gov (United States)

Ruggenthaler, M; Grass, J; Schuh, W; Huber, C G; Reischl, R J

2017-09-05

For the first time, a comprehensive investigation of the impurity profile of the synthetic thyroid API (active pharmaceutical ingredient) liothyronine sodium (LT 3 Na) was performed by using reversed phase HPLC and advanced structural elucidation techniques including high resolution tandem mass spectrometry (HRMS/MS) and on-line hydrogen-deuterium (H/D) exchange. Overall, 39 compounds were characterized and 25 of these related substances were previously unknown to literature. The impurity classification system recently developed for the closely related API levothyroxine sodium (LT 4 Na) could be applied to the newly characterized liothyronine sodium impurities resulting in a wholistic thyroid API impurity classification system. Furthermore, the mass-spectrometric CID-fragmentation of specific related substances was discussed and rationalized by detailed fragmentation pathways. Moreover, the UV/Vis absorption characteristics of the API and selected impurities were investigated to corroborate chemical structure assignments derived from MS data. Copyright © 2017 Elsevier B.V. All rights reserved.

Atmospheric pressure photo ionization hydrogen/deuterium exchange mass spectrometry--a method to differentiate isomers by mass spectrometry.

Science.gov (United States)

Ahmed, Arif; Kim, Sunghwan

2013-12-01

In this report, a method for in-source hydrogen/deuterium (H/D) exchange at atmospheric pressure is reported. The method was named atmospheric pressure photo ionization hydrogen/deuterium exchange mass spectrometry (APPI HDX MS). H/D exchange was performed by mixing samples dissolved in toluene with CH3OD solvent and analyzing the mixture using atmospheric pressure photo ionization mass spectrometry (APPI-MS). The APPI HDX spectra obtained with contact times between the analyte solution and methanol-OD (CH3OD) of atmospheric pressure. H/D exchange can be performed in any laboratory with a mass spectrometer and a commercial APPI source. Using this method, multiple H/D exchanges of aromatic hydrogen and/or H/D exchange of active hydrogen were observed. These results demonstrated that H/D exchange can be used to distinguish between isomers containing primary, secondary, and tertiary amines, as well as pyridine and pyrrole functional groups.

Non-equilibrium hydrogen exchange for determination of H-bond strength and water accessibility in solid proteins.

Science.gov (United States)

Grohe, Kristof; Movellan, Kumar Tekwani; Vasa, Suresh Kumar; Giller, Karin; Becker, Stefan; Linser, Rasmus

2017-05-01

We demonstrate measurement of non-equilibrium backbone amide hydrogen-deuterium exchange rates (HDX) for solid proteins. The target of this study are the slowly exchanging residues in solid samples, which are associated with stable secondary-structural elements of proteins. These hydrogen exchange processes escape methods measuring equilibrium exchange rates of faster processes. The method was applied to a micro-crystalline preparation of the SH3 domain of chicken α-spectrin. Therefore, from a 100% back-exchanged micro-crystalline protein preparation, the supernatant buffer was exchanged by a partially deuterated buffer to reach a final protonation level of approximately 20% before packing the sample in a 1.3 mm rotor. Tracking of the HN peak intensities for 2 weeks reports on site-specific hydrogen bond strength and also likely reflects water accessibility in a qualitative manner. H/D exchange can be directly determined for hydrogen-bonded amides using 1 H detection under fast magic angle spinning. This approach complements existing methods and provides the means to elucidate interesting site-specific characteristics for protein functionality in the solid state.

Estimation of Hydrogen-Exchange Protection Factors from MD Simulation Based on Amide Hydrogen Bonding Analysis

Science.gov (United States)

Park, In-Hee; Venable, John D.; Steckler, Caitlin; Cellitti, Susan E.; Lesley, Scott A.; Spraggon, Glen; Brock, Ansgar

2015-01-01

Hydrogen exchange (HX) studies have provided critical insight into our understanding of protein folding, structure and dynamics. More recently, Hydrogen Exchange Mass Spectrometry (HX-MS) has become a widely applicable tool for HX studies. The interpretation of the wealth of data generated by HX-MS experiments as well as other HX methods would greatly benefit from the availability of exchange predictions derived from structures or models for comparison with experiment. Most reported computational HX modeling studies have employed solvent-accessible-surface-area based metrics in attempts to interpret HX data on the basis of structures or models. In this study, a computational HX-MS prediction method based on classification of the amide hydrogen bonding modes mimicking the local unfolding model is demonstrated. Analysis of the NH bonding configurations from Molecular Dynamics (MD) simulation snapshots is used to determine partitioning over bonded and non-bonded NH states and is directly mapped into a protection factor (PF) using a logistics growth function. Predicted PFs are then used for calculating deuteration values of peptides and compared with experimental data. Hydrogen exchange MS data for Fatty acid synthase thioesterase (FAS-TE) collected for a range of pHs and temperatures was used for detailed evaluation of the approach. High correlation between prediction and experiment for observable fragment peptides is observed in the FAS-TE and additional benchmarking systems that included various apo/holo proteins for which literature data were available. In addition, it is shown that HX modeling can improve experimental resolution through decomposition of in-exchange curves into rate classes, which correlate with prediction from MD. Successful rate class decompositions provide further evidence that the presented approach captures the underlying physical processes correctly at the single residue level. This assessment is further strengthened in a comparison of

The Inhibitive Action Of Sodium Soya Sulphonate Towards The Corrosion Of Aluminium In Hydrochloric Acid

OpenAIRE

Mourad, M. Y.; Mead, A. I.; Seliman, S. A.

1993-01-01

The dissolution of aluminium in 2M hydrochloric acid in the presence of sodium soya sulphonate (SSS) as corrosion inhibitor has been studied using hydrogen evolution and thermometric methods. The two methods gave consistent results. The results obtained indicate that the inhibitive effect of the sulphonated mixture relates to chemisorption mechanism on the metal surface via the n electrons in the double bonds. تمت دراسة ذوبان الألمونيوم في محلول 2 مولارى من حمض الهيدروكلوريك في وجود سلفونا...

Process for the exchange of hydrogen isotopes using a catalyst packed bed assembly

International Nuclear Information System (INIS)

Butler, J.P.; den Hartog, J.; Molson, F.W.R.

1978-01-01

A process for the exchange of hydrogen isotopes between streams of gaseous hydrogen and liquid water is described, wherein the streams of liquid water and gaseous hydrogen are simultaneously brought into contact with one another and a catalyst packed bed assembly while at a temperature in the range 273 0 to 573 0 K. The catalyst packed bed assembly may be composed of discrete carrier bodies of e.g. ceramics, metals, fibrous materials or synthetic plastics with catalytically active metal crystallites selected from Group VIII of the Periodic Table, partially enclosed in and bonded to the carrier bodies by a water repellent, water vapor and hydrogen gas permeable, porous, polymeric material, and discrete packing bodies having an exterior surface which is substantially hydrophilic and relatively noncatalytically active with regard to hydrogen isotope exchange between hydrogen gas and water vapor to that of the catalyst bodies

Quantitative determination of a hydrogen impurity in a sodium coolant by hydride thermal dissociation

Science.gov (United States)

Ivanovskiy, M. N.; Pavlova, G. D.; Shmatko, B. A.; Milovidova, A. V.; Konovalov, E. YE.; Arnoldov, M. N.; Pleshivtsev, A. D.

1988-01-01

A molten sodium coolant containing hydrogen was heated in a vacuum at 450 C, and the gases generated pumped through a liquid nitrogen trap, and the H2 was then oxidized on a copper oxide substrate heated to 400 C. The accuracy of the method is 1.5 percent and the sensitivity is 1x10 to the -5 wt percent hydrogen.

By-Product Carrying Humidified Hydrogen: An Underestimated Issue in the Hydrolysis of Sodium Borohydride.

Science.gov (United States)

Petit, Eddy; Miele, Philippe; Demirci, Umit B

2016-07-21

Catalyzed hydrolysis of sodium borohydride generates up to four molecules of hydrogen, but contrary to what has been reported so far, the humidified evolved gas is not pure hydrogen. Elemental and spectroscopic analyses show, for the first time, that borate by-products pollute the stream as well as the vessel. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isotopic exchange rate of sodium ions between hydrous metal oxides and aqueous solutions

International Nuclear Information System (INIS)

Inoue, Yasushi; Yamazaki, Hiromichi

1991-01-01

To elucidate the kinetics of ion-exchange reaction on hydrous metal oxide, the isotopic exchange rates of sodium ions between hydrous metal oxides such as hydrous tin (IV), niobium (V), zirconium (IV) and titanium (IV) oxides, and aqueous solutions were measured radiochemically and compared with each other. The rate of reaction cannot be understood by an unified view since the rate controlling step differs with the kind of exchangers. The rate constants relevant to each exchanger such as diffusion constants and their activation energies were also determined. (author)

Difluoroborane, a hydrogen-deuterium exchange catalyst. Application to pentaborane (9) and methylpentaborane (9)

International Nuclear Information System (INIS)

Kline, G.A.; Porter, R.F.

1981-01-01

The hydrogen exchange reaction of pentaborane with difluoroborane suggests the existence of a multicentered intermediate similar to that proposed by DeStefano and Porter for the difluoroborane-borazine exchange reaction. A similar intermediate may apply to the borane-pentaborane exchange reaction

Hydrogen generation and storage from hydrolysis of sodium borohydride in batch reactors

Energy Technology Data Exchange (ETDEWEB)

Pinto, A.M.F.R.; Falcao, D.S. [Departamento de Eng. Quimica, Centro de Estudos de Fenomenos de Transporte, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Silva, R.A.; Rangel, C.M. [Instituto Nacional de Engenharia e Tecnologia e Inovacao, Paco do Lumiar 22, 1649-038 (Portugal)

2006-08-15

The catalytic hydrolysis of alkaline sodium borohydride (NaBH{sub 4}) solution was studied using a non-noble; nickel-based powered catalyst exhibiting strong activity even after long time storage. This easy-to-prepare catalyst showed an enhanced activity after being recovered from previous use. The effects of temperature, NaBH{sub 4} concentration, NaOH concentration and pressure on the hydrogen generation rate were investigated. Particular importance has the effect of pressure, since the maximum reached pressure of hydrogen is always substantially lower than predictions (considering 100% conversion) due to solubility effects. The solubility of hydrogen is greatly enhanced by the rising pressure during reaction, leading to storage of hydrogen in the liquid phase. This effect can induce new ways of using this type of catalyst and reactor for the construction of hydrogen generators and even containers for portable and in situ applications. (author)

Hydrogen/Chlorine exchange reactions of gaseous carbanions.

Science.gov (United States)

Chen, Hao; Cooks, R Graham; Meurer, Eduardo C; Eberlin, Marcos N

2005-12-01

Gas-phase reactions of three typical carbanions CH(2)NO(2)(-), CH(2)CN(-), and CH(2)S(O)CH(3)(-) with the chloromethanes CH(2)Cl(2), CHCl(3), and CCl(4), examined by tandem mass spectrometry, show a novel hydrogen/chlorine exchange reaction. For example, reaction between the nitromethyl anion CH(2)NO(2)(-) and carbon tetrachloride CCl(4) forms the ion CHClNO(2)(-). The suggested reaction mechanism involves nucleophilic attack by CH(2)NO(2)(-) at the chlorine of CCl(4) followed by proton transfer within the resulting complex [CH(2)ClNO(2) + CCl(3)(-)] to form CHClNO(2)(-) and CHCl(3). Two other carbanions CH(2)CN(-) and CH(2)S(O)CH(3)(-) also undergo the novel hydrogen/chlorine exchange reactions with CCl(4) but to a much smaller extent, their higher nucleophilicities favoring competitive nucleophilic attack reactions. Proton abstraction is the exclusive pathway in the reactions of these carbanions with CHCl(3). While CH(2)CN(-) and CH(2)S(O)CH(3)(-) promote mainly proton abstraction and nucleophilic displacement in reactions with CH(2)Cl(2), CH(2)NO(2)(-) does not react.

Concept development of exchange liquid regeneration

International Nuclear Information System (INIS)

Mader, D.L.

1985-08-01

Concepts are described for regeneration of the intermediate liquid used for isotope exchange in indirect laser isotope separation processes where the laser operates on a process gas distinct from the feed stream. The specific case of regeneration of an exchange liquid consisting of water, sodium hydroxide, and dimethyl sulfoxide for a process to separate deuterium from hydrogen using laser irradiation of trifluoromethane gas is developed. A water feed stream is converted to steam which rises in a chemical process column where it redeuterates a descending flow of exchange liquid without causing significant changes in its chemical composition

Efficiency of Al2O3 supported palladium sorbents in the process of hydrogen isotope exchange

International Nuclear Information System (INIS)

Andreev, B.M.; Perevezentsev, A.N.; Yasenkov, V.I.

1981-01-01

It is found that in the hydrogen-palladium system while applying the metal to aluminium oxide a considerable increase of the heterogeneous hydrogen isotopic exchange rate is observed due to the increase of its specific surface at 167-298 K temperatures and 350-500 Torr hydrogen pressures. It is shown that in the process of thermal treatment of the supported palladium sorbent resulting in reconstruction of the carrier porous structure, as well as in increasing the metal crystal size, the change of the stage, limiting the isotopic exchange process, occurs. The values of the rate and energy of activation of the hydrogen isotopic exchange are presented [ru

Understanding oscillatory phenomena in molecular hydrogen generation via sodium borohydride hydrolysis.

Science.gov (United States)

Budroni, M A; Biosa, E; Garroni, S; Mulas, G R C; Marchettini, N; Culeddu, N; Rustici, M

2013-11-14

The hydrolysis of borohydride salts represents one of the most promising processes for the generation of high purity molecular hydrogen under mild conditions. In this work we show that the sodium borohydride hydrolysis exhibits a fingerprinting periodic oscillatory transient in the hydrogen flow over a wide range of experimental conditions. We disproved the possibility that flow oscillations are driven by supersaturation phenomena of gaseous bubbles in the reactive mixture or by a nonlinear thermal feedback according to a thermokinetic model. Our experimental results indicate that the NaBH4 hydrolysis is a spontaneous inorganic oscillator, in which the hydrogen flow oscillations are coupled to an "oscillophor" in the reactive solution. The discovery of this original oscillator paves the way for a new class of chemical oscillators, with fundamental implications not only for testing the general theory on oscillations, but also with a view to chemical control of borohydride systems used as a source of hydrogen based green fuel.

The problems of using a high-temperature sodium coolant in nuclear power plants for the production of hydrogen and other innovative applications

Science.gov (United States)

Sorokin, A. P.; Alexeev, V. V.; Kuzina, Ju. A.; Konovalov, M. A.

2017-11-01

The intensity of the hydrogen sources arriving from the third contour of installation in second in comparison with the hydrogen sources on NPP BN-600 increases by two - three order at using of high-temperature nuclear power plants with the sodium coolant (HT-NPP) for drawing of hydrogen and other innovative applications (gasification and a liquefaction of coal, profound oil refining, transformation of biomass to liquid fuel, in the chemical industry, metallurgy, the food-processing industry etc.). For these conditions basic new technological solutions are offered. The main condition of their implementation is raise of hydrogen concentration in the sodium coolant on two - three order in comparison with the modern NPP, in a combination to hydrogen removal from sodium and its pumping out through membranes from vanadium or niobium. The researches with use diffusive model have shown possibility to expel a casium inflow in sodium through a leakproof shell of fuel rods if vary such parameters as a material of fuel rods shell, its thickness and maintenance time at design of fuel rods for high-temperature NPP. However maintenance of high-temperature NPP in the presence of casium in sodium is inevitable at loss of leakproof of a fuel rods shell. In these conditions for minimisation of casium diffusion in structural materials it is necessary to provide deep clearing of sodium from cesium.

Modeling and Validation of Sodium Plugging for Heat Exchangers in Sodium-cooled Fast Reactor Systems

Energy Technology Data Exchange (ETDEWEB)

Ferroni, Paolo [Westinghouse Electric Company LLC, Cranberry Township, PA (United States). Global Technology Development; Tatli, Emre [Westinghouse Electric Company LLC, Cranberry Township, PA (United States); Czerniak, Luke [Westinghouse Electric Company LLC, Cranberry Township, PA (United States); Sienicki, James J. [Argonne National Lab. (ANL), Argonne, IL (United States); Chien, Hual-Te [Argonne National Lab. (ANL), Argonne, IL (United States); Yoichi, Momozaki [Argonne National Lab. (ANL), Argonne, IL (United States); Bakhtiari, Sasan [Argonne National Lab. (ANL), Argonne, IL (United States)

2016-06-29

The project “Modeling and Validation of Sodium Plugging for Heat Exchangers in Sodium-cooled Fast Reactor Systems” was conducted jointly by Westinghouse Electric Company (Westinghouse) and Argonne National Laboratory (ANL), over the period October 1, 2013- March 31, 2016. The project’s motivation was the need to provide designers of Sodium Fast Reactors (SFRs) with a validated, state-of-the-art computational tool for the prediction of sodium oxide (Na₂O) deposition in small-diameter sodium heat exchanger (HX) channels, such as those in the diffusion bonded HXs proposed for SFRs coupled with a supercritical CO₂ (sCO₂) Brayton cycle power conversion system. In SFRs, Na₂O deposition can potentially occur following accidental air ingress in the intermediate heat transport system (IHTS) sodium and simultaneous failure of the IHTS sodium cold trap. In this scenario, oxygen can travel through the IHTS loop and reach the coldest regions, represented by the cold end of the sodium channels of the HXs, where Na₂O precipitation may initiate and continue. In addition to deteriorating HX heat transfer and pressure drop performance, Na₂O deposition can lead to channel plugging especially when the size of the sodium channels is small, which is the case for diffusion bonded HXs whose sodium channel hydraulic diameter is generally below 5 mm. Sodium oxide melts at a high temperature well above the sodium melting temperature such that removal of a solid plug such as through dissolution by pure sodium could take a lengthy time. The Sodium Plugging Phenomena Loop (SPPL) was developed at ANL, prior to this project, for investigating Na₂O deposition phenomena within sodium channels that are prototypical of the diffusion bonded HX channels envisioned for SFR-sCO₂ systems. In this project, a Computational Fluid Dynamic (CFD) model capable of simulating the thermal-hydraulics of the SPPL test

Hydrogen production by high-temperature gas-cooled reactor. Conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system

International Nuclear Information System (INIS)

Sakaba, Nariaki; Ohashi, Hirofumi; Sato, Hiroyuki; Hara, Teruo; Kato, Ryoma; Kunitomi, Kazuhiko

2008-01-01

Nuclear hydrogen production is necessary in an anticipated hydrogen society that demands a massive quantity of hydrogen without economic disadvantage. Japan Atomic Energy Agency (JAEA) has launched the conceptual design study of a hydrogen production system with a near-term plan to connect it to Japan's first high-temperature gas-cooled reactor HTTR. The candidate hydrogen production system is based on the thermochemical water-splitting iodine sulphur (IS) process.The heat of 10 MWth at approximately 900degC, which can be provided by the secondary helium from the intermediate heat exchanger of the HTTR, is the energy input to the hydrogen production system. In this paper, we describe the recent progresses made in the conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system. A new concept of sulphuric acid decomposer is proposed. This involves the integration of three separate functions of sulphuric acid decomposer, sulphur trioxide decomposer, and process heat exchanger. A new mixer-settler type of Bunsen reactor is also designed. This integrates three separate functions of Bunsen reactor, phase separator, and pump. The new concepts are expected to result in improved economics through construction and operation cost reductions because the number of process equipment and complicated connections between the equipment has been substantially reduced. (author)

Hydrolysis and regeneration of sodium borohydride (NaBH4) - A combination of hydrogen production and storage

Science.gov (United States)

Chen, W.; Ouyang, L. Z.; Liu, J. W.; Yao, X. D.; Wang, H.; Liu, Z. W.; Zhu, M.

2017-08-01

Sodium borohydride (NaBH4) hydrolysis is a promising approach for hydrogen generation, but it is limited by high costs, low efficiency of recycling the by-product, and a lack of effective gravimetric storage methods. Here we demonstrate the regeneration of NaBH4 by ball milling the by-product, NaBO2·2H2O or NaBO2·4H2O, with MgH2 at room temperature and atmospheric pressure without any further post-treatment. Record yields of NaBH4 at 90.0% for NaBO2·2H2O and 88.3% for NaBO2·4H2O are achieved. This process also produces hydrogen from the splitting of coordinate water in hydrated sodium metaborate. This compensates the need for extra hydrogen for generating MgH2. Accordingly, we conclude that our unique approach realizes an efficient and cost-effective closed loop system for hydrogen production and storage.

Decomposing method for ion exchange resin

International Nuclear Information System (INIS)

Sako, Takeshi; Sato, Shinshi; Akai, Yoshie; Moniwa, Shinobu; Yamada, Kazuo

1998-01-01

The present invention concerns a method of decomposing ion exchange resins generated in a nuclear power plant to carbon dioxide reliably in a short period of time. (1) The ion exchange resins are mixed with water, and then they are kept for a predetermined period of time in the presence of an inert gas at high temperature and high pressure exceeding the critical point of water to decompose the ion exchange resins. (2) The ion exchange resins is mixed with water, an oxidant is added and they are kept for a predetermined time in the presence of an inert gas at a high temperature and a high pressure exceeding a critical point of water of an inert gas at a high temperature to decompose the ion exchange resins. (3) An alkali or acid is added to ion exchange resins and water to control the hydrogen ion concentration in the solution and the ion exchange resins are decomposed in above-mentioned (1) or (2). Sodium hydroxide is used as the alkali and hydrochloric acid is used as the acid. In addition, oxygen, hydrogen peroxide or ozone is used as an oxidant. (I.S.)

Reversible effects of acute hypertension on proximal tubule sodium transporters

DEFF Research Database (Denmark)

Zhang, Y; Magyar, C E; Norian, J M

1998-01-01

Acute hypertension provokes a rapid decrease in proximal tubule sodium reabsorption with a decrease in basolateral membrane sodium-potassium-ATPase activity and an increase in the density of membranes containing apical membrane sodium/hydrogen exchangers (NHE3) [Y. Zhang, A. K. Mircheff, C. B....... Renal cortex lysate was fractionated on sorbitol gradients. Basolateral membrane sodium-potassium-ATPase activity (but not subunit immunoreactivity) decreased one-third to one-half after BP was elevated and recovered after BP was normalized. After BP was elevated, 55% of the apical NHE3 immunoreactivity......, smaller fractions of sodium-phosphate cotransporter immunoreactivity, and apical alkaline phosphatase and dipeptidyl-peptidase redistributed to membranes of higher density enriched in markers of the intermicrovillar cleft (megalin) and endosomes (Rab 4 and Rab 5), whereas density distributions...

On the proton exchange contribution to electron-hydrogen atom elastic scattering

International Nuclear Information System (INIS)

Mignaco, J.A.; Tort, A.C.

1979-05-01

It is shown that the exchange contribution to the electron-proton potential Born term in elastic electron-hydrogen atom scattering arises as the non relativistic limit from the exchange of a proton between the two participant electrons - calculated from quantum electrodynamics including properly bound states (as solution of Bethe - Salpeter equation). (Author) [pt

Resonance charge exchange between excited states in slow proton-hydrogen collisions

International Nuclear Information System (INIS)

Tolstikhina, Inga Yu.; Kato, Daiji

2010-01-01

The theory of resonance charge exchange in slow collisions of a proton with a hydrogen atom in the excited state is developed. It extends the Firsov-Demkov theory of resonance charge exchange to the case of degenerate initial and final states. The theory is illustrated by semiclassical and quantum calculations of charge exchange cross sections between states with n=2 in parabolic and spherical coordinates. The results are compared with existing close-coupling calculations.

User's manual of BISHOP. A Bi-Phase, Sodium-Hydrogen-Oxygen system, chemical equilibrium calculation program

International Nuclear Information System (INIS)

Okano, Yasushi; Yamaguchi, Akira

2001-07-01

In an event of sodium leakage in liquid metal fast breeder reactors, liquid sodium flows out of piping, and droplet combustion might occur under a certain environmental condition. The combustion heat and reaction products should be evaluated in the sodium fire analysis codes for investigating the influence of the sodium leak age and fire incident. In order to analyze the reaction heat and products, the multi-phase chemical equilibrium calculation program for a sodium, oxygen and hydrogen system has been developed. The developed numerical program is named BISHOP, which denotes 'Bi-Phase, Sodium-Hydrogen-Oxygen, Chemical Equilibrium Calculation Program'. The Gibbs free energy minimization method is used because of the following advantages. Chemical species are easily added and changed. A variety of thermodynamic states, such as isothermal and isentropic changes, can be dealt with in addition to constant temperature and pressure processes. In applying the free energy minimization method to solve the multi-phase sodium reaction system, three new numerical calculation techniques are developed. One is theoretical simplification of phase description in equation system, the other is to extend the Gibbs free energy minimization method to a multi-phase system, and the last is to establish the efficient search for the minimum value. The reaction heat and products at the equilibrium state can be evaluated from the initial conditions, such as temperature, pressure and reactants, using BISHOP. This report describes the thermochemical basis of chemical equilibrium calculations, the system of equations, simplification models, and the procedure to prepare input data and usage of BISHOP. (author)

Hydrogen/deuterium exchange of multiply-protonated cytochrome c ions

International Nuclear Information System (INIS)

Wood, T.D.; Guan, Ziqiang; O'Connor, P.B.

1995-01-01

Low resolution measurements show gaseous multiply-protonated cytochrome c ions undergo hydrogen/deuterium (H/D) exchange with pseudo first-order kinetics at three distinct exchange levels, suggesting the co-existence of gaseous protein conformations. Although exchange levels first increase with increasing charge values, they decrease at the highest charge values, consistent with solution-phase behavior of cytochrome c, where the native structure unfolds with decreasing pH until folding into a compact A-state at lowest pH. High resolution measurements indicate the presence of at least six H/D exchange levels. Infrared (IR) laser heating and fast collisions via quadrupolar excitation (QE) increase H/D exchange levels (unfolding) while charge-stripping ions to lower charge values can increase or decrease H/D exchange levels (unfolding or folding). Wolynes has suggested studying proteins in vacuo could play an important role in delineating the contributions various forces play in the protein folding process, provided appropriate comparisons can be made between gas-phase and solution-phase structures

Effect of tolvaptan on renal water and sodium excretion and blood pressure during nitric oxide inhibition

DEFF Research Database (Denmark)

Therwani, Safa Al; Rosenbæk, Jeppe Bakkestrøm; Mose, Frank Holden

2017-01-01

BACKGROUND: Tolvaptan is a selective vasopressin receptor antagonist. Nitric Oxide (NO) promotes renal water and sodium excretion, but the effect is unknown in the nephron's principal cells. In a dose-response study, we measured the effect of tolvaptan on renal handling of water and sodium....... CONCLUSIONS: During baseline, fractional excretion of sodium was unchanged. During tolvaptan with NO-inhibition, renal water excretion was reduced dose dependently, and renal sodium excretion was reduced unrelated to the dose, partly via an AVP dependent mechanism. Thus, tolvaptan antagonized the reduction...... in renal water and sodium excretion during NO-inhibition. Most likely, the lack of decrease in AQP2 excretion by tolvaptan could be attributed to a counteracting effect of the high level of p-AVP....

The design and commissioning of cold trap purifying system of hydrogen meter sodium loop

International Nuclear Information System (INIS)

Zhao Zhaoyi; Jia Baoshan; Chen Xiaoming; Pan Fengguo

1993-01-01

The design feature and parameters of cold trap purifying system of hydrogen meter sodium loop and its commissioning results are reported and discussed. In order to adjust the flow easily,. the cold trap purifying system is arranged in the exit of the electromagnetic pump. It is composed of regenerator and the cold trap. The regenerator is above the cold trap. The high temperature sodium in the main-loop flows through the regenerator, in the entrance of the cold trap, its temperature is reduced to 180 degree C. After entering into the cold trap, the sodium flows to the purifying region by side, when it arrives the bottom of the trap, its temperature is reduced to 110 degree C. The cold trap is cooled by air. The temperature of the clean sodium rises nearby the main-loop's by the regenerator, and then it returns to the entrance of the electromagnetic pump. According to the commissioning results, the sodium's temperature of the cold trap could be reduced to 110 degree C by reducing the flow of the cold trap purifying system and the temperature of the main-loop, or increasing the air flow and cutting off the power supply of its heating. The authors think that the latter is more conformable with the design stipulation and with the requirement of the hydrogen meter experiment, and it can meet the requirements of the operation of the Nuclear Power Plant

Sodium-hydrogen exchange in erythrocytes of patients with acute deep venous thromboses.

Science.gov (United States)

Polykarpov, S A; Orlov, S N

1992-05-15

The rate of delta microH(+)-induced Na/H-exchange in erythrocytes of patients with occlusive and with floating types of acute deep venous thromboses, and in control volunteers, was estimated. In patients with occlusive thrombi Na/H-exchange was revealed to be fourfold higher in comparison with patients with floating thrombi and with controls, while no difference was observed between the two latter groups.

CFD Modeling of Sodium-Oxide Deposition in Sodium-Cooled Fast Reactor Compact Heat Exchangers

Energy Technology Data Exchange (ETDEWEB)

Tatli, Emre; Ferroni, Paolo; Mazzoccoli, Jason

2015-09-02

The possible use of compact heat exchangers (HXs) in sodium-cooled fast reactors (SFR) employing a Brayton cycle is promising due to their high power density and resulting small volume in comparison with conventional shell-and-tube HXs. However, the small diameter of their channels makes them more susceptible to plugging due to Na2O deposition during accident conditions. Although cold traps are designed to reduce oxygen impurity levels in the sodium coolant, their failure, in conjunction with accidental air ingress into the sodium boundary, could result in coolant oxygen levels that are above the saturation limit in the cooler parts of the HX channels. This can result in Na2O crystallization and the formation of solid deposits on cooled channel surfaces, limiting or even blocking coolant flow. The development of analysis tools capable of modeling the formation of these deposits in the presence of sodium flow will allow designers of SFRs to properly size the HX channels so that, in the scenario mentioned above, the reactor operator has sufficient time to detect and react to the affected HX. Until now, analytical methodologies to predict the formation of these deposits have been developed, but never implemented in a high-fidelity computational tool suited to modern reactor design techniques. This paper summarizes the challenges and the current status in the development of a Computational Fluid Dynamics (CFD) methodology to predict deposit formation, with particular emphasis on sensitivity studies on some parameters affecting deposition.

Analysis of the sodium concrete interactions with the NABE code

International Nuclear Information System (INIS)

Soule, N.

1989-01-01

Experimental studies have been performed in France to investigate sodium-concrete interactions: thermal decomposition of concrete, specific chemical reactions, experimentation in liquid and vapour phase, sodium-concrete interaction without liner protection. Simultaneously computer codes have been developed in order to study the response of the containment building of a liquid metal fast breeder reactor to a sodium pool fire worsened by a sodium-concrete interaction: the NABE code. This code takes into account: a) sodium combustion; b) thermal decomposition of concrete with associated chemical reactions: (liquid sodium-vapour water reaction, liquid sodium-carbon dioxide reaction, liquid sodium-solid compounds of concrete, hydrogen combustion); c) chemical reactions in vapour phase; d) decay heat; e) gas aerosol inlets/outlets; f) aerosol behaviour (sedimentation, diffusion, leak); g) thermal exchanges. An example of a situation, typical of assessment of beyond design basis situations in LMFBR, is given. (author)

An evaluation of the fluid-elastic instability for Intermediate Heat Exchanger of Prototype Sodium-cooled fast Reactor

International Nuclear Information System (INIS)

Cho, Jaehun; Kim, Sungkyun; Koo, Gyeonghoi

2014-01-01

The sodium-cooled fast reactor (SFR) module consists of the vessel, containment vessel, head, rotating plug (RP), upper internal structure (UIS), intermediate heat exchanger (IHX), decay heat exchanger (DHX), primary pump, internal structure, internal components and reactor core. The IHXs transfer heat from the radioactive sodium coolant (primary sodium) in the primary heat transport system to the nonradioactive sodium coolant (secondary sodium) in the intermediate heat transport system. Each sodium flows like Fig. 1. Primary sodium flows inside of tube and secondary sodium flows outside. During transferring heat two sodium to sodium, the fluid-elastic instability is occurred among tube bundle by cross flow. Large amplitude vibration occurred by the fluid-elastic instability is caused such as crack and wear of tube. Thus it is important to decrease the fluid-elastic instability in terms of a safety. The purpose of this paper is to evaluate the fluid-elastic instability for tube bundle in the IHX following ASME code. This paper evaluated the fluid-elastic instability of tube bundle in the SFR IHX. According evaluation results, the fluid-elastic instability of IHX tube bundle is occurred. A installing an additional TSP under the upper tubesheet can decrease a probability of fluid-elastic instability. If a location of an additional TSP does not exceed tube length to become a 750 mm, tube bundle of IHX is safety from the fluid-elastic instability

Large scale experiments with a 5 MW sodium/air heat exchanger for decay heat removal

International Nuclear Information System (INIS)

Stehle, H.; Damm, G.; Jansing, W.

1994-01-01

Sodium experiments in the large scale test facility ILONA were performed to demonstrate proper operation of a passive decay heat removal system for LMFBRs based on pure natural convection flow. Temperature and flow distributions on the sodium and the air side of a 5 MW sodium/air heat exchanger in a natural draught stack were measured during steady state and transient operation in good agreement with calculations using a two dimensional computer code ATTICA/DIANA. (orig.)

A new concept of hydrogen production system for sodium cooled FBR

International Nuclear Information System (INIS)

Nakagiri, Toshio; Aoto, Kazumi; Hoshiya, Taiji

2004-01-01

A new thermo-chemical and electrolytic hybrid hydrogen production process (thermo-chemical and electrolytic Hybrid Hydrogen process in Lower Temperature range: HHLT) is newly proposed by the Japan Nuclear Cycle Development Institute (JNC) to realize the hydrogen production from water by using the heat generation of sodium cooled Fast Breeding Reactor (FBR). The HHLT process is based on the sulfuric acid (H 2 SO 4 ) synthesis and decomposition processes developed earlier (Westinghouse process), and sulfur trioxide (SO 3 ) decomposition process of HHLT is facilitated by electrolysis with ionic oxygen conductive solid electrolyte to reduce operating temperature 200degC-300degC lower than Westinghouse process. Decomposition processes of SO 3 were confirmed with the cell voltage lower than 0.5 V at 500degC-600degC using 8mol yttria stabilized zirconia (8molYSZ) solid electrolyte and platinum electrode. Therefore, total voltage required for HHLT is expected to be lower than 1.0 V, because the voltage required for sulfuric acid synthesis is about 0.5V. Thermal efficiency of HHLT based on chemical reactions was roughly estimated to be within the range of 35% to 55% under the influence of H 2 SO 4 concentration and heat recovery. These results show the possibility of development of a new hydrogen production process which needs low splitting voltage and has high efficiency at around 500degC, utilizing the heat generation of sodium cooled FBR. SO 3 splitting with the voltage lower than 0.5V was confirmed at about 500degC experimentally, and ideal thermal efficiency of the cycle based on chemical reactions was evaluated. Furthermore, test apparatus to substantiate whole process of HHLT was manufactured. (author)

A new type separation column for the water-hydrogen isotope catalytic exchange process

International Nuclear Information System (INIS)

Fedorchenko, O.A.; Alekseev, I.A.; Trenin, V.D.

2001-01-01

The catalytic water/hydrogen isotope exchange process is by right considered the most attractive for the solution a number of urgent problems of hydrogen isotope separation. A new type exchange reaction column is described and studied in details by computer simulation and with the help of McCabe-Thiele diagrams. It is shown that the new column in comparison with a traditional one needs less catalyst quantity and a smaller diameter for the solving of the same separation tasks. Generalized calculation data are presented in graphical form

O--H charge exchange in cold, dense, hydrogen plasmas

International Nuclear Information System (INIS)

Cohen, S.A.; Dylla, H.F.

1977-05-01

It is pointed out that the accidentally resonant charge exchange reaction, O + + H 0 reverse arrows O 0 + H + , is an important mechanism for causing the loss of singly charged oxygen ions from oxygen contaminated hydrogen plasmas. Results of a Monte Carlo simulation are presented which show that the fraction of oxygen lost because of charge exchange exceeds 1 / 3 when the parameters n/sub e/ approx. 10 13 cm -3 , n/sub H//sup o/ approx. 10 11 cm -3 and T/sub e/ approx. 3 eV are attained

Combined electrolysis catalytic exchange (CECE) process for hydrogen isotope separation

International Nuclear Information System (INIS)

Hammerli, M.; Stevens, W.H.; Butler, J.P.

1978-01-01

Hydrogen isotopes can be separated efficiently by a process which combines an electrolysis cell with a trickle bed column packed with a hydrophobic platinum catalyst. The column effects isotopic exchange between countercurrent streams of electrolytic hydrogen and liquid water while the electrolysis cell contributes to isotope separation by virtue of the kinetic isotope effect inherent in the hydrogen evolution reaction. The main features of the CECE process for heavy water production are presented as well as a discussion of the inherent positive synergistic effects, and other advantages and disadvantages of the process. Several potential applications of the process in the nuclear power industry are discussed. 3 figures, 2 tables

Method for ion exchange purification of sodium iodide solution from heavy metals and potassium microimpurities

International Nuclear Information System (INIS)

Smirnov, G.I.; Kachur, N.Ya.; Kostromina, O.N.; Ogorodnikova, A.A.; Khajnakov, S.A.

1990-01-01

A method of deep ion exchange purification of sodium iodide solution from heavy metals (iron, nickel, copper, lead) and potassium microimpurities is developed. The method includes multiple sorption of microimpurities on titanium phosphate with their subsequent desorption by sorbent processing with a solution with a solution of 3-6 N nitric acid, first, and then with a neutral solution of 2 % sodium thiosulfate. The given method permits to increase the purification degree of sodium iodide solution by 25-30 %. 2 tabs

Sodium-calcium ion exchange on clay minerals at moderate to high ionic strengths

International Nuclear Information System (INIS)

Rogers, W.J.

1979-12-01

Sodium-calcium ion exchange on several clay minerals was studied at ionic strengths ranging from 0.01 to above 1.0. The minerals studied included attapulgite, illite, kaolin, and several montmorillonites. Distribution coefficients of calcium and sodium were obtained for the minerals over a wide range of solution conditions at pH five and equilibrium constants were calculated. The distribution coefficient of calcium, D/sub Ca/, was studied as a function of time, solution pH, loading, sodium concentration, and ionic strength fraction of sodium in constant ionic strength solutions. The distribution coefficient of sodium, D/sub Na/, was also studied as a function of time, loading, and sodium ionic strength fraction in constant total ionic strength solutions. Values of equilibrium constants calculated from distribution coefficients for solutions of constant ionic strength scattered bwteen 2 and 10 kg/kg for the montmorillonites and attapulgite while equilibrium constants for illite ranged from 5 to 10 kg/kg. No equilibrium constants for kaolin were calculated since distribution coefficients of sodium on this clay were too small to be measured. It was found that equilibrium constants at trace sodium loading were generally lower than those for higher sodium loadings by an order of magnitude or more due to the sensitivity of sodium distribution coefficients to the concentration of sodium in the clay at low loadings. Theoretical and experimental treatments of ion exclusion were included

Carbon-supported cobalt catalyst for hydrogen generation from alkaline sodium borohydride solution

Energy Technology Data Exchange (ETDEWEB)

Xu, Dongyan; Liu, Xinmin; Cao, Changqing; Guo, Qingjie [College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Dai, Ping [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China)

2008-08-01

Low cost transition metal catalysts with high performance are attractive for the development of on-board hydrogen generation systems by catalytic hydrolysis of sodium borohydride (NaBH{sub 4}) in fuel cell fields. In this study, hydrogen production from alkaline NaBH{sub 4} via hydrolysis process over carbon-supported cobalt catalysts was studied. The catalytic activity of the supported cobalt catalyst was found to be highly dependent on the calcination temperatures. The hydrogen generation rate increases with calcination temperatures in the range of 200-400 C, but a high calcination temperature above 500 C led to markedly decreased activity. X-ray diffraction patterns reveal that the catalysts experience phase transition from amorphous Co-B to crystalline cobalt hydroxide with increase in calcination temperatures. The reaction performance is also dependent on the concentration of NaBH{sub 4}, and the hydrogen generation rate increases for lower NaBH{sub 4} concentrations and decreases after reaching a maximum at 10 wt.% of NaBH{sub 4}. (author)

The influence of the water chemistry regime of the third circuit on the corrosion hydrogen burden to the secondary sodium circuit in the steam generator model of BN-800 reactor

International Nuclear Information System (INIS)

Smykov, V.B.; Ermolaev, N.P.; Kolesnik, A.I.; Egorov, V.A.; Shevchenko, N.N.

1994-01-01

An experimental program was conducted to determine the influence of water chemistry on the corrosion hydrogen burden from the III circuit to the secondary sodium in sodium-heated rig of OTSG of NPP BN-800. Combined water chemistry has given the best passivative effect on steam-generating surfaces and smallest hydrogen burden to secondary sodium during start-up. Common hydrogen increasing in secondary sodium was less then 0.2 ppm. In case of AVT water chemistry (NH 3 +N 2 H 4 ) in III side of OTSG-rig the hydrogen level in secondary sodium was 1.0-1.2 ppm. It means that during first start-up at NPP BN-800 the common hydrogen level in secondary sodium may reaches 0.80-0.85 ppm. 4 figs.; 4 tabs

Sodium removal from CSRDM lower part by water vapour - CO2 process

International Nuclear Information System (INIS)

Sundar Raj, S.I.; Sreedhar, B.K.; Gurumoorthy, K.; Rajan, K.K.; Kalyanasundaram, P.; Rajan, M.; Vaidyanathan, G.

2006-01-01

Sodium is the primary and secondary coolant in fast reactors. Primary and secondary circuits components like Control and Safety Rod Drive Mechanism (CSRDM), pumps, heat exchangers etc. handle liquid sodium. Sodium has good affinity to oxygen and reacts vigorously with water. Hence sodium cleaning is the first and important activity in the maintenance of the components. In reactor components this cleaning process also helps in removing a major part of radioactive contaminants after which they are subjected to chemical decontamination. There are several methods available for removing sodium from components. Out of these, the water vapour-CO 2 process is selected for large components such as pumps, heat exchangers etc. while steam cleaning is used for the core sub assemblies. The cleaning processes are to be closely monitored to ensure safety because the release of hydrogen is to be kept below 4 % during the process. This paper discusses the in house facility and the experience in the successful use of the process in the cleaning of CSRDM. (author)

New method for the hydrogen isotope exchange reaction in a hydrophobic catalyst bed

International Nuclear Information System (INIS)

Asakura, Y.; Kikuchi, M.; Yusa, H.

1982-01-01

To improve the isotope exchange reaction efficiency between water and hydrogen, a new reactor in which water mists and hydrogen gas react cocurrently was studied. To apply this to the enrichment of tritium in heavy water, a dual temperature isotope exchange reactor which is composed of cocurrent low temperature reactors and the usual countercurrent high temperature reactor was proposed and analyzed using a McCabe-Thiele diagram. By utilizing cocurrent reactors, in combination, the necessary catalyst volume can be reduced to one-tenth as compared with the usual countercurrent low temperature reactor. 17 refs

Kinetics of tritium isotope exchange between liquid pyrrole and gaseous hydrogen

International Nuclear Information System (INIS)

Stolarz, A.

1994-01-01

The kinetics of tritium isotope exchange between liquid pyrrole and gaseous hydrogen has been studied over the temperature range of 290-303 K. The reaction was carried out in the presence of platinum black but in spite of that, it appeared to be relatively slow. The kinetics of the exchange reaction studied could be described by the simple McKay equation. The results obtained suggest that diffusion is the rate-determining step. A mechanism of exchange is proposed. (author) 10 refs.; 2 figs.; 1 tab

Pressure drop and heat transfer in the sodium to air heat exchanger tube banks on advanced sodium-cooled fast reactor

International Nuclear Information System (INIS)

Kang, H.; Eoh, J.; Cha, J.; Kim, S.

2011-01-01

A numerical study was performed to investigate the thermal and hydraulic characteristics and build up design model of the AHX (sodium-to-air heat exchanger) unit of a sodium-cooled fast reactor. Helical-coiled tube banks in the AHX were modeled as porous media and simulated heat and momentum transfer. Two-dimensional flow characteristic appeared at the most region of AHX annulus. Pressure drop and heat transfer coefficient for rectangular, parallelogram and staggered tube banks as the main components of the AHX were evaluated and compared with Zhukauskas empirical correlations. (author)

Hydrogen-deuterium exchange in imidazole as a tool for studying histidine phosphorylation.

Science.gov (United States)

Cebo, Małgorzata; Kielmas, Martyna; Adamczyk, Justyna; Cebrat, Marek; Szewczuk, Zbigniew; Stefanowicz, Piotr

2014-12-01

Isotope exchange at the histidine C2 atom of imidazole in D2O solution is well known to occur at a significantly slower rate than the exchange of amide protons. Analysis of the kinetics of this isotope-exchange reaction is proposed herein as a method of detecting histidine phosphorylation. This modification of His-containing peptides is challenging to pinpoint because of its instability under acidic conditions as well as during CID-MS analysis. In this work, we investigated the effect of phosphorylation of the histidine side chain in peptides on deuterium-hydrogen exchange (DHX) in the imidazole. The results demonstrate that phosphorylation dramatically slows the rate of the DHX reaction. This phenomenon can be applied to detect phosphorylation of peptides at the histidine residue (e.g., in enzymatic digests). We also found that the influence of the peptide sequence on the exchange kinetics is relatively small. A CID fragmentation experiment revealed that there was no detectable hydrogen scrambling in peptides deuterated at C2 of the imidazole ring. Therefore, MS/MS can be used to directly identify the locations of deuterium ions incorporated into peptides containing multiple histidine moieties.

Measurement of exchangeable sodium: 22Na or 24Na

International Nuclear Information System (INIS)

Smith, T.; Edmonds, C.J.

1987-01-01

A case is made for the use of 22 Na in low activities in preference to 24 Na for routine diagnostic estimation of exchangeable sodium, and is based chiefly on considerations of availability, cost and radiation dosimetry. A method in which only 37 kBq (1 μCi) 22 Na is administered orally is shown to be sufficiently accurate and to possess distinct advantages in terms of cost and convenience with a committed radiation dose no greater than that for a measurement using 24 Na. (author)

Ammonia-water exchange front end process for ammonia-hydrogen heavy water plants (Preprint No. PD-1)

International Nuclear Information System (INIS)

Sadhukhan, H.K.; Varadarajan, T.G.; Nair, N.K.; Das, S.K.; Nath, G.K.

1989-04-01

The ammonia-hydrogen exchange process, which utilizes the deutrium exchange between liquid ammonia and gaseous hydrogen is a parasitic process and the heavy water plants (HWP) based on this process has to be linked with the fertilizer plant (FP) for its enormous requirements of hydrogen (synthesis gas, N 2 +3H 2 ). This dependence of HWP on FP gives rise to certain constraints which are listed. These deficiencies of the ammonia-hydrogen process can be overcome to a great extent by delinking the HWP from FP by incorporating NH 3 -H 2 O exchange as the front end step. In addition to the elimination of the above limitations, by employing water as the ultimate feed for the HWP, the plant capacity can be increased substantially and this would go a long way in achieving economies of the large capacity plants. A schematic diagram of this integrated plant is given. Some of the results of developmental efforts and feasibility studies of this NH 3 -H 2 O exchange are briefly reviewed. (author). 4 figs

Sodium tetra-hydro-borate as energy/hydrogen carrier, its history

International Nuclear Information System (INIS)

Demirci, U.B.; Miele, Ph.

2009-01-01

Sodium tetra-hydro-borate NaBH 4 is considered as being a promising energy/hydrogen carrier. NaBH 4 is not a new compound. It has been discovered in 1940's by Prof. H.C. Brown, Nobel Laureate in Chemistry in 1979. NaBH 4 has thus a history and this history distinguishes the NaBH 4 utilisation as hydrogen carrier from that as energy carrier. In fact, the history of NaBH 4 (for both utilizations) can be divided into three periods, each period being characterised by specific societal challenges. Whereas during the first period the challenges were military and political, the challenges in the third period (i.e. at present) are energetic, environmental, civilian, social and political. The second period was rather calm for NaBH 4 even if it was intensively used as a reducing agent in organic chemistry. (authors)

Determination of Backbone Amide Hydrogen Exchange Rates of Cytochrome c Using Partially Scrambled Electron Transfer Dissociation Data

Science.gov (United States)

Hamuro, Yoshitomo; E, Sook Yen

2018-05-01

The technological goal of hydrogen/deuterium exchange-mass spectrometry (HDX-MS) is to determine backbone amide hydrogen exchange rates. The most critical challenge to achieve this goal is obtaining the deuterium incorporation in single-amide resolution, and gas-phase fragmentation may provide a universal solution. The gas-phase fragmentation may generate the daughter ions which differ by a single amino acid and the difference in deuterium incorporations in the two analogous ions can yield the deuterium incorporation at the sub-localized site. Following the pioneering works by Jørgensen and Rand, several papers utilized the electron transfer dissociation (ETD) to determine the location of deuterium in single-amide resolution. This paper demonstrates further advancement of the strategy by determining backbone amide hydrogen exchange rates, instead of just determining deuterium incorporation at a single time point, in combination with a wide time window monitoring. A method to evaluate the effects of scrambling and to determine the exchange rates from partially scrambled HDX-ETD-MS data is described. All parent ions for ETD fragmentation were regio-selectively scrambled: The deuterium in some regions of a peptide ion was scrambled while that in the other regions was not scrambled. The method determined 31 backbone amide hydrogen exchange rates of cytochrome c in the non-scrambled regions. Good fragmentation of a parent ion, a low degree of scrambling, and a low number of exchangeable hydrogens in the preceding side chain are the important factors to determine the exchange rate. The exchange rates determined by the HDX-MS are in good agreement with those determined by NMR. [Figure not available: see fulltext.

Determination of Backbone Amide Hydrogen Exchange Rates of Cytochrome c Using Partially Scrambled Electron Transfer Dissociation Data.

Science.gov (United States)

Hamuro, Yoshitomo; E, Sook Yen

2018-05-01

The technological goal of hydrogen/deuterium exchange-mass spectrometry (HDX-MS) is to determine backbone amide hydrogen exchange rates. The most critical challenge to achieve this goal is obtaining the deuterium incorporation in single-amide resolution, and gas-phase fragmentation may provide a universal solution. The gas-phase fragmentation may generate the daughter ions which differ by a single amino acid and the difference in deuterium incorporations in the two analogous ions can yield the deuterium incorporation at the sub-localized site. Following the pioneering works by Jørgensen and Rand, several papers utilized the electron transfer dissociation (ETD) to determine the location of deuterium in single-amide resolution. This paper demonstrates further advancement of the strategy by determining backbone amide hydrogen exchange rates, instead of just determining deuterium incorporation at a single time point, in combination with a wide time window monitoring. A method to evaluate the effects of scrambling and to determine the exchange rates from partially scrambled HDX-ETD-MS data is described. All parent ions for ETD fragmentation were regio-selectively scrambled: The deuterium in some regions of a peptide ion was scrambled while that in the other regions was not scrambled. The method determined 31 backbone amide hydrogen exchange rates of cytochrome c in the non-scrambled regions. Good fragmentation of a parent ion, a low degree of scrambling, and a low number of exchangeable hydrogens in the preceding side chain are the important factors to determine the exchange rate. The exchange rates determined by the HDX-MS are in good agreement with those determined by NMR. Graphical Abstract ᅟ.

Determination of Backbone Amide Hydrogen Exchange Rates of Cytochrome c Using Partially Scrambled Electron Transfer Dissociation Data

Science.gov (United States)

Hamuro, Yoshitomo; E, Sook Yen

2018-03-01

The technological goal of hydrogen/deuterium exchange-mass spectrometry (HDX-MS) is to determine backbone amide hydrogen exchange rates. The most critical challenge to achieve this goal is obtaining the deuterium incorporation in single-amide resolution, and gas-phase fragmentation may provide a universal solution. The gas-phase fragmentation may generate the daughter ions which differ by a single amino acid and the difference in deuterium incorporations in the two analogous ions can yield the deuterium incorporation at the sub-localized site. Following the pioneering works by Jørgensen and Rand, several papers utilized the electron transfer dissociation (ETD) to determine the location of deuterium in single-amide resolution. This paper demonstrates further advancement of the strategy by determining backbone amide hydrogen exchange rates, instead of just determining deuterium incorporation at a single time point, in combination with a wide time window monitoring. A method to evaluate the effects of scrambling and to determine the exchange rates from partially scrambled HDX-ETD-MS data is described. All parent ions for ETD fragmentation were regio-selectively scrambled: The deuterium in some regions of a peptide ion was scrambled while that in the other regions was not scrambled. The method determined 31 backbone amide hydrogen exchange rates of cytochrome c in the non-scrambled regions. Good fragmentation of a parent ion, a low degree of scrambling, and a low number of exchangeable hydrogens in the preceding side chain are the important factors to determine the exchange rate. The exchange rates determined by the HDX-MS are in good agreement with those determined by NMR. [Figure not available: see fulltext.

On the method of heat exchange calculation for critical and postcritical regimes in sodium-water steam generators

International Nuclear Information System (INIS)

Khudasko, V.V.; Kardash, D.Yu.; Grachev, N.S.

1986-01-01

Technique for calculating heat exchange in sodium-water steam generators with provisions for steam-water flow non-equilibrium character and moisture additional evaporation in pipes is suggested. Zone of heat exchange crisis representing the zone of transition from developed boiling to postcritical zone is considered. Comparison of estimated and experimental data performed for the following ranges of steame generator parameters: pressure p=7.8-14.0 MPa, coolant flow rate ρw=350-1000 kg/(m 2 xs), inlet sodium temperature T=590-825 K shows their good agreement

On line determination of deuterium in hydrogen water exchange reaction by mass spectrometry. IRP-10

International Nuclear Information System (INIS)

Sharma, J.D.; Alphonse, K.P.; Mishra, Sushama; Prabhu, S.A.; Mohan, Sadhana; Tangri, V.K.

2007-01-01

The Deuterium (D)/Hydrogen (H) analysis at low Concentration is generally carried out by Mass Spectrometry. Mass Spectrometer is specially designed for the measurement of Mass 2 and 3 ratio. The Deuterium analysis of water and hydrogen in concentration range of a few ppm to about 1% plays an important role in the Heavy Water Production Plants. For the enrichment of the Deuterium concentration in H 2 O by H 2 - H 2 O exchange a catalyst is essential as reaction is relatively slow. Heavy Water Division has developed in house Platinum based catalyst for the isotopic exchange of Hydrogen and Water

Side-chain dynamics of a detergent-solubilized membrane protein: Measurement of tryptophan and glutamine hydrogen-exchange rates in M13 coat protein by 1H NMR spectroscopy

International Nuclear Information System (INIS)

O'Neil, J.D.J.; Sykes, B.D.

1989-01-01

M13 coat protein is a small (50 amino acids) lipid-soluble protein that becomes an integral membrane protein during the infection stage of the life cycle of the M13 phage and is therefore used as a model membrane protein. To study side-chain dynamics in the protein, the authors have measured individual hydrogen-exchange rates for a primary amide in the side chain of glutamine-15 and for the indole amine of tryptophan-26. The protein was solubilized with the use of perdeuteriated sodium dodecyl sulfate (SDS), and hydrogen-exchange rates were measured by using 1 H nuclear magnetic resonance spectroscopy. The glutamine-15 syn proton exchanged at a rate identical with that in glutamine model peptides except that the pH corresponding to minimum exchange was elevated by about 1.5 pH units. The tryptophan-26 indole amine proton exchange was biphasic, suggesting that two populations of tryptophan-26 exist. It is suggested that the two populations may reflect protein dimerization or aggregation in the SDS micelles. The pH values of minimum exchange for tryptophan-26 in both environments were also elevated by 1.3-1.9 pH units. This phenomenon is reproduced when small tryptophan- and glutamine-containing hydrophobic peptides are dissolved in the presence of SDS micelles. The electrostatic nature of this phenomenon is proven by showing that the minimum pH for exchange can be reduced by dissolving the hydrophobic peptides in the positively charged detergent micelle dodecyltrimethylammonium bromide

Evaluation of steam-to-sodium leak detectors in the sodium components test installation (SCTI)

Energy Technology Data Exchange (ETDEWEB)

McKee, J M; Simmons, W R

1975-07-01

Two nickel diffusion-membrane type hydrogen detectors were installed in the secondary sodium system of the Sodium Components Test Installation and evaluated during the 12-month performance test of the Modular Steam Generator (MSG). Hydrogen in the expansion tank cover gas was monitored with a gas chromatograph. During this period, numerous steam and hydrogen injections were made, simulating steam leaks into the sodium of an LMFBR steam generator. The response of the detectors was evaluated for leak sizes ranging from 10{sup -6} to 10{sup -4} 1b H{sub 2}O/sec, injection periods of 0.5 to 300 min, secondary sodium flow rates of 0.2 x 10{sup 6} to 1.5 x 10{sup 6} 1b/hr, and sodium temperatures of 400 to 950 deg. F. The response of the leak detection system was influenced significantly by two regimes of sodium temperature. Below 600 deg. F, the cover gas hydrogen detector gave the largest response; this is attributed to the long dissolution time of hydrogen bubbles relative to the transit time of hydrogen to the expansion tank. Above 600 deg. F, the hydrogen apparently dissolved rapidly and the detectors were much more effective in the sodium than in the cover gas. At least 75% of the hydrogen and 50% of the oxygen content of injected steam appeared as detectable activity if the reaction products were dispersed in the sodium stream and the sodium was above 600 deg. F. Hydrogen injections into semi-stagnant sodium at the MSG tube sheets were detected with better sensitivity than steam injections into the main sodium stream. It appeared that high local concentrations of hydrogen were quickly carried to the nearest detector by upward currents created by the injected gas. The alarm system functioned as expected, 2.1 ppb/min being the smallest rate-of-rise in hydrogen concentration to give an automatic alarm. With more sensitive rate-of-rise alarm settings, leaks as small as 2 x 10{sup -5} 1b H{sub 2}O/sec could be detected in a system such as the Clinch River Breeder

Evaluation of steam-to-sodium leak detectors in the sodium components test installation (SCTI)

International Nuclear Information System (INIS)

McKee, J.M.; Simmons, W.R.

1975-01-01

Two nickel diffusion-membrane type hydrogen detectors were installed in the secondary sodium system of the Sodium Components Test Installation and evaluated during the 12-month performance test of the Modular Steam Generator (MSG). Hydrogen in the expansion tank cover gas was monitored with a gas chromatograph. During this period, numerous steam and hydrogen injections were made, simulating steam leaks into the sodium of an LMFBR steam generator. The response of the detectors was evaluated for leak sizes ranging from 10 -6 to 10 -4 1b H 2 O/sec, injection periods of 0.5 to 300 min, secondary sodium flow rates of 0.2 x 10 6 to 1.5 x 10 6 1b/hr, and sodium temperatures of 400 to 950 deg. F. The response of the leak detection system was influenced significantly by two regimes of sodium temperature. Below 600 deg. F, the cover gas hydrogen detector gave the largest response; this is attributed to the long dissolution time of hydrogen bubbles relative to the transit time of hydrogen to the expansion tank. Above 600 deg. F, the hydrogen apparently dissolved rapidly and the detectors were much more effective in the sodium than in the cover gas. At least 75% of the hydrogen and 50% of the oxygen content of injected steam appeared as detectable activity if the reaction products were dispersed in the sodium stream and the sodium was above 600 deg. F. Hydrogen injections into semi-stagnant sodium at the MSG tube sheets were detected with better sensitivity than steam injections into the main sodium stream. It appeared that high local concentrations of hydrogen were quickly carried to the nearest detector by upward currents created by the injected gas. The alarm system functioned as expected, 2.1 ppb/min being the smallest rate-of-rise in hydrogen concentration to give an automatic alarm. With more sensitive rate-of-rise alarm settings, leaks as small as 2 x 10 -5 1b H 2 O/sec could be detected in a system such as the Clinch River Breeder Reactor Plant. A preliminary

Physiological Functions and Regulation of the Na+/H+ Exchanger [NHE1] in Renal Tubule Epithelial Cells

Directory of Open Access Journals (Sweden)

Patricia G Vallés

2015-08-01

Full Text Available The sodium-hydrogen exchanger isoform-1 [NHE1] is a ubiquitously expressed plasma membrane protein that plays a central role in intracellular pH and cell volume homeostasis by catalyzing an electroneutral exchange of extracellular sodium and intracellular hydrogen. Outside of this important physiological function, the NHE1 cytosolic tail domain acts as a molecular scaffold regulating cell survival and actin cytoskeleton organization through NHE1-dependent signaling proteins. NHE1 plays main roles in response to physiological stress conditions which in addition to cell shrinkage and acidification, include hypoxia and mechanical stimuli, such as cell stretch. NHE1-mediated modulation of programmed cell death results from the exchanger-mediated changes in pHi, cell volume, and/or [Na+]I; and, it has recently become known that regulation of cellular signaling pathways are involved as well. This review focuses on NHE1 functions and regulations. We describe evidence showing how these structural actions integrate with ion translocation in regulating renal tubule epithelial cell survival.

Two-photon exchange correction to the hyperfine splitting in muonic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Tomalak, Oleksandr [Johannes Gutenberg Universitaet, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

2017-12-15

We reevaluate the Zemach, recoil and polarizability corrections to the hyperfine splitting in muonic hydrogen expressing them through the low-energy proton structure constants and obtain the precise values of the Zemach radius and two-photon exchange (TPE) contribution. The uncertainty of TPE correction to S energy levels in muonic hydrogen of 105 ppm exceeds the ppm accuracy level of the forthcoming 1S hyperfine splitting measurements at PSI, J-PARC and RIKEN-RAL. (orig.)

METAMORPHIC INHIBITION OF XENOPUS LAEVIS BY SODIUM PERCHLORATE: EFFECTS ON DEVELOPMENT AND THYROID HISTOLOGY

Science.gov (United States)

The perchlorate anion inhibits thyroid hormone (TH) synthesis via inhibition of the sodium-iodide symporter. It is, therefore, a good model chemical to aid in the development of a bioassay to screen chemicals for effects on thyroid function. Xenopus laevis larvae were exposed to ...

Gas-phase ion/molecule isotope-exchange reactions: methodology for counting hydrogen atoms in specific organic structural environments by chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Hunt, D.F.; Sethi, S.K.

1980-01-01

Ion/molecule reactions are described which facilitate exchange of hydrogens for deuteriums in a variety of different chemical environments. Aromatic hydrogens in alkylbenzenes, oxygenated benzenes, m-toluidine, m-phenylenediamine, thiophene, and several polycyclic aromatic hydrocarbons and metallocenes are exchanged under positive ion CI conditions by using either D 2 O, EtOD, or ND 3 as the reagent gas. Aromatic hydrogens, benzylic hydrogens, and hydrogens on carbon adjacent to carbonyl groups suffer exchange under negative ion CI conditions in ND 3 , D 2 O, and EtOD, respectively. A possible mechanism for the exchange process is discussed. 1 figure, 2 tables

Hydrogen storage in sodium aluminum hydride.

Energy Technology Data Exchange (ETDEWEB)

Ozolins, Vidvuds; Herberg, J.L. (Lawrence Livermore National Laboratories, Livermore, CA); McCarty, Kevin F.; Maxwell, Robert S. (Lawrence Livermore National Laboratories, Livermore, CA); Stumpf, Roland Rudolph; Majzoub, Eric H.

2005-11-01

Sodium aluminum hydride, NaAlH{sub 4}, has been studied for use as a hydrogen storage material. The effect of Ti, as a few mol. % dopant in the system to increase kinetics of hydrogen sorption, is studied with respect to changes in lattice structure of the crystal. No Ti substitution is found in the crystal lattice. Electronic structure calculations indicate that the NaAlH{sub 4} and Na{sub 3}AlH{sub 6} structures are complex-ionic hydrides with Na{sup +} cations and AlH{sub 4}{sup -} and AlH{sub 6}{sup 3-} anions, respectively. Compound formation studies indicate the primary Ti-compound formed when doping the material at 33 at. % is TiAl{sub 3} , and likely Ti-Al compounds at lower doping rates. A general study of sorption kinetics of NaAlH{sub 4}, when doped with a variety of Ti-halide compounds, indicates a uniform response with the kinetics similar for all dopants. NMR multiple quantum studies of solution-doped samples indicate solvent interaction with the doped alanate. Raman spectroscopy was used to study the lattice dynamics of NaAlH{sub 4}, and illustrated the molecular ionic nature of the lattice as a separation of vibrational modes between the AlH{sub 4}{sup -} anion-modes and lattice-modes. In-situ Raman measurements indicate a stable AlH{sub 4}{sup -} anion that is stable at the melting temperature of NaAlH{sub 4}, indicating that Ti-dopants must affect the Al-H bond strength.

Backbone dynamics of a model membrane protein: measurement of individual amide hydrogen-exchange rates in detergent-solubilized M13 coat protein using 13C NMR hydrogen/deuterium isotope shifts

International Nuclear Information System (INIS)

Henry, G.D.; Weiner, J.H.; Sykes, B.D.

1987-01-01

Hydrogen-exchange rates have been measured for individual assigned amide protons in M13 coat protein, a 50-residue integral membrane protein, using a 13 C nuclear magnetic resonance (NMR) equilibrium isotope shift technique. The locations of the more rapidly exchanging amides have been determined. In D 2 O solutions, a peptide carbonyl resonance undergoes a small upfield isotope shift (0.08-0.09 ppm) from its position in H 2 O solutions; in 1:1 H 2 O/D 2 O mixtures, the carbonyl line shape is determined by the exchange rate at the adjacent nitrogen atom. M13 coat protein was labeled biosynthetically with 13 C at the peptide carbonyls of alanine, glycine, phenylalanine, proline, and lysine, and the exchange rates of 12 assigned amide protons in the hydrophilic regions were measured as a function of pH by using the isotope shift method. This equilibrium technique is sensitive to the more rapidly exchanging protons which are difficult to measure by classical exchange-out experiments. In proteins, structural factors, notably H bonding, can decrease the exchange rate of an amide proton by many orders of magnitude from that observed in the freely exposed amides of model peptides such as poly(DL-alanine). With corrections for sequence-related inductive effects, the retardation of amide exchange in sodium dodecyl sulfate solubilized coat protein has been calculated with respect to poly(DL-alanine). The most rapidly exchanging protons, which are retarded very little or not at all, are shown to occur at the N- and C-termini of the molecule. A model of the detergent-solubilized coat protein is constructed from these H-exchange data which is consistent with circular dichroism and other NMR results

Hydrogen-tritium exchange survey of allosteric effects in hemoglobin

International Nuclear Information System (INIS)

Englander, J.J.; Englander, S.W.

1987-01-01

The oxy and deoxy forms of hemoglobin display major differences in H-exchange behavior. Hydrogen-tritium exchange experiments on hemoglobin were performed in the low-resolution mode to observe the dependence of these differences on pH (Bohr effect), organic phosphates, and salt. Unlike a prior report, increasing pH was found to decrease the oxy-deoxy difference monotonically, in general accordance with the alkaline Bohr effect. A prior report that the H-exchange difference between oxy- and deoxyhemoglobin vanishes at pH 9, and thus appears to reflect the Bohr effect alone, was found to be due to the borate buffer used, which at high pH tends to abolish the oxy-deoxy difference in a limited region of the H-exchange curve. Effects on hemoglobin H exchange due to organic phosphates parallel the differential binding of these agents (inositol hexaphosphate more than diphosphoglycerate, deoxy more than oxy, at low pH more than at high pH). Added salt slows H exchange of deoxyhemoglobin and has no effect on the oxy form. These results display the sensitivity of simple H-exchange measurements for finding and characterizing effects on structure and dynamics that may occur anywhere in the protein and help to define conditions for higher resolution approaches that can localize the changes observed

Hydrothermal Synthesis of Co-Ru Alloy Particle Catalysts for Hydrogen Generation from Sodium Borohydride

Directory of Open Access Journals (Sweden)

Marija Kurtinaitienė

2013-01-01

Full Text Available We report the synthesis of μm and sub-μm-sized Co, Ru, and Co-Ru alloy species by hydrothermal approach in the aqueous alkaline solutions (pH ≥ 13 containing CoCl2 and/or RuCl3, sodium citrate, and hydrazine hydrate and a study of their catalytic properties for hydrogen generation by hydrolysis of sodium borohydride solution. This way provides a simple platform for fabrication of the ball-shaped Co-Ru alloy catalysts containing up to 12 wt% Ru. Note that bimetallic Co-Ru alloy bowls containing even 7 at.% Ru have demonstrated catalytic properties that are comparable with the ones of pure Ru particles fabricated by the same method. This result is of great importance in view of the preparation of cost-efficient catalysts for hydrogen generation from borohydrides. The morphology and composition of fabricated catalyst particles have been characterized using scanning electron microscopy, energy dispersive X-ray diffraction, and inductively coupled plasma optical emission spectrometry.

Methylamine-hydrogen exchange Part III. Physicochemical properties of amide-amine solutions

International Nuclear Information System (INIS)

Srinivasa, K.; Dave, S.M.

1983-01-01

Different physicochemical properties of potassium methylamide/methylamine solutions have been compiled and reviewed. These properties will be quite useful in design calculations for plants based on amine-hydrogen exchange for the production of heavy water. (author)

Water-hydrogen isotope exchange process analysis

International Nuclear Information System (INIS)

Fedorchenko, O.; Alekseev, I.; Uborsky, V.

2008-01-01

The use of a numerical method is needed to find a solution to the equation system describing a general case of heterogeneous isotope exchange between gaseous hydrogen and liquid water in a column. A computer model of the column merely outputting the isotope compositions in the flows leaving the column, like the experimental column itself, is a 'black box' to a certain extent: the solution is not transparent and occasionally not fully comprehended. The approximate analytical solution was derived from the ZXY-diagram (McCabe-Thiele diagram), which illustrates the solution of the renewed computer model called 'EVIO-4.2' Several 'unusual' results and dependences have been analyzed and explained. (authors)

Hydraulic conductivity in response to exchangeable sodium percentage and solution salt concentration

Directory of Open Access Journals (Sweden)

Jefferson Luiz de Aguiar Paes

2014-10-01

Full Text Available Hydraulic conductivity is determined in laboratory assays to estimate the flow of water in saturated soils. However, the results of this analysis, when using distilled or deionized water, may not correspond to field conditions in soils with high concentrations of soluble salts. This study therefore set out to determine the hydraulic conductivity in laboratory conditions using solutions of different electrical conductivities in six soils representative of the State of Pernambuco, with the exchangeable sodium percentage adjusted in the range of 5-30%. The results showed an increase in hydraulic conductivity with both decreasing exchangeable sodium percentage and increasing electrical conductivity in the solution. The response to the treatments was more pronounced in soils with higher proportion of more active clays. Determination of hydraulic conductivity in laboratory is routinely performed with deionized or distilled water. However, in salt affected soils, these determinations should be carried out using solutions of electrical conductivity different from 0 dS m-1, with values close to those determined in the saturation extracts.

Inhibition of copper corrosion in sodium chloride solution by the self-assembled monolayer of sodium diethyldithiocarbamate

Energy Technology Data Exchange (ETDEWEB)

Liao, Q.Q., E-mail: liaoqq1971@yahoo.com.c [Key Lab of Shanghai Colleges and Universities for Electric Power Corrosion Control and Applied Electrochemistry, Shanghai Engineering Research Center of Energy - Saving in Heat Exchange Systems, Shanghai University of Electric Power, Shanghai 200090 (China); Yue, Z.W.; Yang, D. [Key Lab of Shanghai Colleges and Universities for Electric Power Corrosion Control and Applied Electrochemistry, Shanghai Engineering Research Center of Energy - Saving in Heat Exchange Systems, Shanghai University of Electric Power, Shanghai 200090 (China); Wang, Z.H. [Department of Chemistry, Tongji University, Shanghai 200092 (China); Li, Z.H. [Department of Chemistry, Fudan University, Shanghai 200433 (China); Ge, H.H. [Key Lab of Shanghai Colleges and Universities for Electric Power Corrosion Control and Applied Electrochemistry, Shanghai Engineering Research Center of Energy - Saving in Heat Exchange Systems, Shanghai University of Electric Power, Shanghai 200090 (China); Li, Y.J. [Department of Chemistry, Tongji University, Shanghai 200092 (China)

2011-05-15

Research highlights: DDTC is of low toxicity. DDTC SAM had good corrosion inhibition effects on copper in 3% NaCl solution. DDTC SAM was chemisorbed on copper surface by its S atoms. - Abstract: Sodium diethyldithiocarbamate (DDTC) self-assembled monolayer (SAM) on copper surface has been investigated by SERS and EDS and the results show that DDTC SAM is chemisorbed on copper surface by its S atoms with tilted orientation. Corrosion inhibition ability of DDTC SAM was measured in 3% NaCl solution using electrochemical methods. The impedance results indicate that the maximum inhibition efficiency of DDTC SAM can reach 99%. Quantum chemical calculations show that DDTC has relatively small {Delta}E between HOMO and LUMO and large negative charge in its two sulfur atoms, which facilitates the formation of a DDTC SAM on copper surface.

Hydrogen/deuterium exchange of cross-linkable alpha-amino acid derivatives in deuterated triflic acid

OpenAIRE

Wang, Lei; Murai, Yuta; Yoshida, Takuma; Okamoto, Masashi; Masuda, Katsuyoshi; Sakihama, Yasuko; Hashidoko, Yasuyuki; Hatanaka, Yasumaru; Hashimoto, Makoto

2014-01-01

In this paper we report here a hydrogen/deuterium exchange (H/D exchange) of cross-linkable alpha-amino acid derivatives with deuterated trifluoromethanesulfonic acid (TfOD). H/D exchange with TfOD was easily applied to o-catechol containing phenylalanine (DOPA) within an hour. A partial H/D exchange was observed for trifluoromethyldiazirinyl (TFMD) phenylalanine derivatives. N-Acetyl-protected natural aromatic alpha-amino acids (Tyr and Trp) were more effective in H/D exchange than unprotect...

Modification of interlayer exchange coupling in Fe/V/Fe trilayers using hydrogen

Energy Technology Data Exchange (ETDEWEB)

Skoryna, J., E-mail: jskoryna@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland); Marczyńska, A. [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland); Lewandowski, M. [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85 St., 61-614 Poznań (Poland); Smardz, L. [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland)

2015-10-05

Highlights: • Magnetic films and multilayers. • Thin films. • Hydrogen absorbing materials. • Magnetic measurements. • Exchange coupling. - Abstract: Fe/V/Fe trilayers with constant-thickness Fe and step-like wedged V sublayers were prepared at room temperature using UHV magnetron sputtering. The bottom Fe layer grows onto oxidised Si(1 0 0) substrate and shows relatively high coercivity. The top Fe layer grows on vanadium spacer and shows considerably lower coercivity. The planar growth of the Fe and V sublayers was confirmed in-situ by X-ray photoelectron spectroscopy. Results show that the Fe sublayers are weakly exchange coupled for d{sub V} > 1.4 nm. Results on the coercivity studies as a function of the V interlayer thickness show near d{sub V} ∼ 1.95 nm (∼2.45 nm) weak antiferromagnetic (ferromagnetic) coupling, respectively. The hydrogenation of the Fe/V/Fe trilayers leads to increase of the strength of the ferromagnetic interlayer exchange coupling.

How amide hydrogens exchange in native proteins.

Science.gov (United States)

Persson, Filip; Halle, Bertil

2015-08-18

Amide hydrogen exchange (HX) is widely used in protein biophysics even though our ignorance about the HX mechanism makes data interpretation imprecise. Notably, the open exchange-competent conformational state has not been identified. Based on analysis of an ultralong molecular dynamics trajectory of the protein BPTI, we propose that the open (O) states for amides that exchange by subglobal fluctuations are locally distorted conformations with two water molecules directly coordinated to the N-H group. The HX protection factors computed from the relative O-state populations agree well with experiment. The O states of different amides show little or no temporal correlation, even if adjacent residues unfold cooperatively. The mean residence time of the O state is ∼100 ps for all examined amides, so the large variation in measured HX rate must be attributed to the opening frequency. A few amides gain solvent access via tunnels or pores penetrated by water chains including native internal water molecules, but most amides access solvent by more local structural distortions. In either case, we argue that an overcoordinated N-H group is necessary for efficient proton transfer by Grotthuss-type structural diffusion.

How amide hydrogens exchange in native proteins

Science.gov (United States)

Persson, Filip; Halle, Bertil

2015-01-01

Amide hydrogen exchange (HX) is widely used in protein biophysics even though our ignorance about the HX mechanism makes data interpretation imprecise. Notably, the open exchange-competent conformational state has not been identified. Based on analysis of an ultralong molecular dynamics trajectory of the protein BPTI, we propose that the open (O) states for amides that exchange by subglobal fluctuations are locally distorted conformations with two water molecules directly coordinated to the N–H group. The HX protection factors computed from the relative O-state populations agree well with experiment. The O states of different amides show little or no temporal correlation, even if adjacent residues unfold cooperatively. The mean residence time of the O state is ∼100 ps for all examined amides, so the large variation in measured HX rate must be attributed to the opening frequency. A few amides gain solvent access via tunnels or pores penetrated by water chains including native internal water molecules, but most amides access solvent by more local structural distortions. In either case, we argue that an overcoordinated N–H group is necessary for efficient proton transfer by Grotthuss-type structural diffusion. PMID:26195754

Genome-Wide Identification and Analysis of Arabidopsis Sodium Proton Antiporter (NHX and Human Sodium Proton Exchanger (NHE Homologs in Sorghum bicolor

Directory of Open Access Journals (Sweden)

P. Hima Kumari

2018-05-01

Full Text Available Na+ transporters play an important role during salt stress and development. The present study is aimed at genome-wide identification, in silico analysis of sodium-proton antiporter (NHX and sodium-proton exchanger (NHE-type transporters in Sorghum bicolor and their expression patterns under varied abiotic stress conditions. In Sorghum, seven NHX and nine NHE homologs were identified. Amiloride (a known inhibitor of Na+/H+ exchanger activity binding motif was noticed in both types of the transporters. Chromosome 2 was found to be a hotspot region with five sodium transporters. Phylogenetic analysis inferred six ortholog and three paralog groups. To gain an insight into functional divergence of SbNHX/NHE transporters, real-time gene expression was performed under salt, drought, heat, and cold stresses in embryo, root, stem, and leaf tissues. Expression patterns revealed that both SbNHXs and SbNHEs are responsive either to single or multiple abiotic stresses. The predicted protein–protein interaction networks revealed that only SbNHX7 is involved in the calcineurin B-like proteins (CBL- CBL interacting protein kinases (CIPK pathway. The study provides insights into the functional divergence of SbNHX/NHE transporter genes with tissue specific expressions in Sorghum under different abiotic stress conditions.

3.2.1. Synthesis, crystal and molecular structure of catena-(bis(µ1-oxalic acid-µ3-hydrogen oxalate-di-aqua-sodium(I.

Directory of Open Access Journals (Sweden)

Olga Kovalchukova*, Sergey Aldoshin, Andrey Utenyshev, Konstantin Bogenko, Valeriy Tkachev

2015-07-01

Full Text Available The crystal and molecular structure of catena-(bis(µ- oxalic acid-µ-hydrogen oxalate-di-aqua-sodium(I was detected by X-Ray analysis. The compound crystallizes in the triclinic space group P-1, with a(Å 6.2378(12; b(Å 7,1115(14; c(Å 10.489(2; α(° 94.65(3; β(° 100.12(3; γ(° 97.78(3. The sodium cation in the title compound is eight coordinated and forms a square antiprism. It is surrounded by two molecules of oxalic acid, one hydrogen oxalate anion and one water molecule. Both oxalic acid and hydrogen oxalate anion act as polydentate bridging ligands. Centrosymmetric sodium cations are bounded by hydrogen oxalate anions through a system of H bonds involving the molecules of oxalic acid. In the lattice, the 3D structure stabilized by H bonds is formed.

Hydrogen deuterium exchange mass spectrometry in biopharmaceutical discovery and development – A review

International Nuclear Information System (INIS)

Deng, Bin; Lento, Cristina; Wilson, Derek J.

2016-01-01

Protein therapeutics have emerged as a major class of biopharmaceuticals over the past several decades, a trend that has motivated the advancement of bioanalytical technologies for protein therapeutic characterization. Hydrogen deuterium exchange mass spectrometry (HDX-MS) is a powerful and sensitive technique that can probe the higher order structure of proteins and has been used in the assessment and development of monoclonal antibodies (mAbs), antibody-drug conjugates (ADCs) and biosimilar antibodies. It has also been used to quantify protein-ligand, protein-receptor and other protein-protein interactions involved in signaling pathways. In manufacturing and development, HDX-MS can validate storage formulations and manufacturing processes for various biotherapeutics. Currently, HDX-MS is being refined to provide additional coverage, sensitivity and structural specificity and implemented on the millisecond timescale to reveal residual structure and dynamics in disordered domains and intrinsically disordered proteins. - Highlights: • The pharmaceuticals industry is increasingly shifting to protein therapeutics. • Hydrogen deuterium exchange mass spectrometry is uniquely well suited to support biopharmaceutical development. • Applications for hydrogen deuterium exchange span drug discovery, development and manufacturing. • Future developments will allow improved sensitivity, structural resolution and a broader range of dynamics to be monitored.

Hydrogen deuterium exchange mass spectrometry in biopharmaceutical discovery and development – A review

Energy Technology Data Exchange (ETDEWEB)

Deng, Bin, E-mail: dengbin@yorku.ca [Chemistry Department, York University, 4700 Keele Street, Toronto, ON, M3J 1P3 (Canada); The Centre for Research in Mass Spectrometry, York University, Toronto, ON, M3J1P3 (Canada); Lento, Cristina, E-mail: clento@yorku.ca [Chemistry Department, York University, 4700 Keele Street, Toronto, ON, M3J 1P3 (Canada); The Centre for Research in Mass Spectrometry, York University, Toronto, ON, M3J1P3 (Canada); Wilson, Derek J., E-mail: dkwilson@yorku.ca [Chemistry Department, York University, 4700 Keele Street, Toronto, ON, M3J 1P3 (Canada); The Centre for Research in Mass Spectrometry, York University, Toronto, ON, M3J1P3 (Canada)

2016-10-12

Protein therapeutics have emerged as a major class of biopharmaceuticals over the past several decades, a trend that has motivated the advancement of bioanalytical technologies for protein therapeutic characterization. Hydrogen deuterium exchange mass spectrometry (HDX-MS) is a powerful and sensitive technique that can probe the higher order structure of proteins and has been used in the assessment and development of monoclonal antibodies (mAbs), antibody-drug conjugates (ADCs) and biosimilar antibodies. It has also been used to quantify protein-ligand, protein-receptor and other protein-protein interactions involved in signaling pathways. In manufacturing and development, HDX-MS can validate storage formulations and manufacturing processes for various biotherapeutics. Currently, HDX-MS is being refined to provide additional coverage, sensitivity and structural specificity and implemented on the millisecond timescale to reveal residual structure and dynamics in disordered domains and intrinsically disordered proteins. - Highlights: • The pharmaceuticals industry is increasingly shifting to protein therapeutics. • Hydrogen deuterium exchange mass spectrometry is uniquely well suited to support biopharmaceutical development. • Applications for hydrogen deuterium exchange span drug discovery, development and manufacturing. • Future developments will allow improved sensitivity, structural resolution and a broader range of dynamics to be monitored.

Radiation-related retrograde hydrogen isotope and K-Ar exchange in clay minerals

International Nuclear Information System (INIS)

Halter, C.; Pagel, M.; Sheppard, S.M.F.; Weber, F.; Clauer, N.

1987-01-01

Hydrogen and oxygen isotope studies have been widely applied to characterize the origin of fluids during ore-foaming processes. The primary isotope record, however, may be disturbed by retrograde exchange reactions, thus complicating the interpretation of the data. The susceptibility of minerals to retrograde isotope and chemical exchange is variable, reflecting differences in the mechanism and rate of isotope exchange. Results are presented on deuterium depletion, K/Ar ages and H 2 O + content of illites associated with uranium mineralization from the Athabasca basin (Canada). (author)

Hydrogen Exchange Differences between Chemoreceptor Signaling Complexes Localize to Functionally Important Subdomains

Science.gov (United States)

2015-01-01

The goal of understanding mechanisms of transmembrane signaling, one of many key life processes mediated by membrane proteins, has motivated numerous studies of bacterial chemotaxis receptors. Ligand binding to the receptor causes a piston motion of an α helix in the periplasmic and transmembrane domains, but it is unclear how the signal is then propagated through the cytoplasmic domain to control the activity of the associated kinase CheA. Recent proposals suggest that signaling in the cytoplasmic domain involves opposing changes in dynamics in different subdomains. However, it has been difficult to measure dynamics within the functional system, consisting of extended arrays of receptor complexes with two other proteins, CheA and CheW. We have combined hydrogen exchange mass spectrometry with vesicle template assembly of functional complexes of the receptor cytoplasmic domain to reveal that there are significant signaling-associated changes in exchange, and these changes localize to key regions of the receptor involved in the excitation and adaptation responses. The methylation subdomain exhibits complex changes that include slower hydrogen exchange in complexes in a kinase-activating state, which may be partially consistent with proposals that this subdomain is stabilized in this state. The signaling subdomain exhibits significant protection from hydrogen exchange in complexes in a kinase-activating state, suggesting a tighter and/or larger interaction interface with CheA and CheW in this state. These first measurements of the stability of protein subdomains within functional signaling complexes demonstrate the promise of this approach for measuring functionally important protein dynamics within the various physiologically relevant states of multiprotein complexes. PMID:25420045

Annual report 1974. Sodium technology development programme

International Nuclear Information System (INIS)

1975-01-01

The sodium technology development program comprises a number of separate research programs in the field of designing and testing parts and components for the SNR-300 reactor. Design studies and theoretical studies on cold trapping and the behavior of hydrogen in sodium circuits are reported. A preliminary test program for fighting sodium fires is completed. Results of research done on vibration measurements and counter-current mixing in a dummy tube bundle of a S.N.R. spiralized steam generator with counter-current flow are reported briefly. Research done in the field of heat transfer, pressure drop and bubble dynamics of a straight pipe steam generator are also briefly reported. To determine the influence of spiral diameter of the spiralized pipe on heat transfer in a spiralized pipe heat exchanger, a second testsection will be built in 1975. Research was reported on pump viscoseals, bearing stability, rotordynamics and bearing materials for sodium pumps. Research done on the properties of SNR-construction materials at high temperature and long time exposure and corrosion in sodium are reported. Fundamental research on corrosion accompanied this research. The report closes with results of weldability, mechanized-welding and remote welding of sodium-wetted surfaces

Lithium-sodium separation by ion-exchange. Particular study of a pulsed column

International Nuclear Information System (INIS)

Auvert, H.

1966-02-01

A study is made of the operational conditions and constraints in the case of a moving-bed ion-exchange column subjected to pulses. The example chosen to illustrate its application concerns the lithium-sodium separation in a hydroxide medium (LiOH, NaOH). In the first part, the physico-chemical characteristics of the exchange and the kinetic characteristics of the exchange-reaction are considered. In the second part, the operation of the pulsed column is studied. Using the results obtained in the first part, the conditions required for study state operation are determined. When this is obtained, it is possible to calculate the height equivalent of the theoretical plate (HETP) of the installation. A study is also made of 'sliding', a phenomenon peculiar to pulsed columns. The results obtained show that it is possible, using laboratory tests, to determine the characteristics and the operational condition of a moving-bed ion-exchange column. (author) [fr

Effect of geometric factors on performance of a sodium to air heat exchanger in a fast breeder reactor

International Nuclear Information System (INIS)

Kannan, K.; Vinod, V.; Padmakumar, G.; Rudramoorthy, R.; Rajan, K.K.

2015-01-01

Highlights: • A heat exchanger analysis (HE) before scale up reduces excess heat transfer area. • Representative Elementary Volume analysis of a HE speeds up the solution. • The error in air temperature rise prediction by numerical across HE is within 5%. • When both pitches are reduced, the maximum increase in heat flux is experienced. • The experience has resulted in better design of next level heat exchangers. - Abstract: Prototype fast breeder reactor (PFBR) has a safety grade decay heat removal system whose performance depends on the effective functioning of natural convection heat exchangers called sodium to air heat exchangers. The development of Representative Elementary Volume (REV) model for the sodium to air heat exchanger is necessary to envisage its design and to study the effect of various factors for continuous improvement in design. With a Representative Elementary Volume, the hydrodynamic and heat transfer characteristics of the heat exchanger was studied and the results agree well with experimental data. The effect of longitudinal pitch and transverse pitch on the heat exchanger performance has been studied and an improvement of 22% in heat transfer is predicted

Kinetics of isotopic exchange of [1-3H]saccharides with hydrogen using palladium catalysts

International Nuclear Information System (INIS)

Akulov, G.P.; Kayumov, V.G.; Snetkova, E.V.; Kaminskij, Yu.L.

1988-01-01

The kinetics was studied of the isotopic exchange of [1- 3 H]saccharides with hydrogen on palladium catalysts. The effect was studied of different factors on the rate of isotopic exchange, e.g., of the composition and structure of saccharides, their concentration in the solution (C), the type of catalyst and of the buffer solution. It was found that by reduced rate of isotopic exchange with hydrogen, all studied saccharides may be arranged into a series independent of the type of catalyst in accordance with the sequence of declining coefficient of relative mobility of l-H atoms during the reaction. Linear dependence was found to exist between the rate constant of the isotopic exchange reaction (r) and the coefficient of relative lability. It was also found that in the range of low concentrations the observed rate constants of isotopic exchange were not dependent on concentration and in the range of higher concentrations, r decreased with increasing C. This character of dependence is justified by the side effect of the processes of sorption on the catalyst. (author). 3 figs., 1 tab., 4 refs

Model-independent determination of the two-photon exchange contribution to hyperfine splitting in muonic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Peset, Clara; Pineda, Antonio [Grup de Física Teòrica, Dept. Física and IFAE-BIST, Universitat Autònoma de Barcelona,E-08193 Bellaterra (Barcelona) (Spain)

2017-04-11

We obtain a model-independent prediction for the two-photon exchange contribution to the hyperfine splitting in muonic hydrogen. We use the relation of the Wilson coefficients of the spin-dependent dimension-six four-fermion operator of NRQED applied to the electron-proton and to the muon-proton sectors. Their difference can be reliably computed using chiral perturbation theory, whereas the Wilson coefficient of the electron-proton sector can be determined from the hyperfine splitting in hydrogen. This allows us to give a precise model-independent determination of the Wilson coefficient for the muon-proton sector, and consequently of the two-photon exchange contribution to the hyperfine splitting in muonic hydrogen, which reads δĒ{sub pμ,HF}{sup TPE}(nS)=−(1/(n{sup 3}))1.161(20) meV. Together with the associated QED analysis, we obtain a prediction for the hyperfine splitting in muonic hydrogen that reads E{sub pμ,HF}{sup th}(1S)=182.623(27) meV and E{sub pμ,HF}{sup th}(2S)=22.8123(33) meV. The error is dominated by the two-photon exchange contribution.

Separation of rate processes for isotopic exchange between hydrogen and liquid water in packed columns 10

International Nuclear Information System (INIS)

Butler, J.P.; Hartog, J. den; Goodale, J.W.; Rolston, J.H.

1977-01-01

Wetproofed platinum catalysts in packed columns promote isotopic exchange between counter-current streams of hydrogen saturated with water vapour and liquid water. The net rate of deuterium transfer from isotopically enriched hydrogen has been measured and separated into two rate processes involving the transfer of deuterium from hydrogen to water vapour and from water vapour to liquid. These are compared with independent measurements of the two rate processes to test the two-step successive exchange model for trickle bed reactors. The separated transfer rates are independent of bed height and characterize the deuterium concentrations of each stream along the length of the bed. The dependences of the transfer rates upon hydrogen and liquid flow, hydrogen pressure, platinum loading and the effect of dilution of the hydrophobic catalyst with inert hydrophilic packing are reported. The results indicate a third process may be important in the transfer of deuterium between hydrogen and liquid water. (author)

Sodium-glucose cotransporter 2 inhibition and health benefits: The Robin Hood effect.

Science.gov (United States)

Kalra, Sanjay; Jain, Arpit; Ved, Jignesh; Unnikrishnan, A G

2016-01-01

This review discusses two distinct, yet related, mechanisms of sodium-glucose cotransporter 2 (SGLT2) inhibition: Calorie restriction mimicry (CRM) and pro-ketogenic effect, which may explain their cardiovascular benefits. We term these adaptive CRM and pro-ketogenic effects of SGLT2 inhibition, the Robin Hood hypothesis. In English history, Robin Hood was a "good person," who stole from the rich and helped the poor. He supported redistribution of resources as he deemed fit for the common good. In a similar fashion, SGLT2 inhibition provides respite to the overloaded glucose metabolism while utilizing lipid stores for energy production.

Sodium-glucose cotransporter 2 inhibition and health benefits: The Robin Hood effect

Directory of Open Access Journals (Sweden)

Sanjay Kalra

2016-01-01

Full Text Available This review discusses two distinct, yet related, mechanisms of sodium-glucose cotransporter 2 (SGLT2 inhibition: Calorie restriction mimicry (CRM and pro-ketogenic effect, which may explain their cardiovascular benefits. We term these adaptive CRM and pro-ketogenic effects of SGLT2 inhibition, the Robin Hood hypothesis. In English history, Robin Hood was a "good person," who stole from the rich and helped the poor. He supported redistribution of resources as he deemed fit for the common good. In a similar fashion, SGLT2 inhibition provides respite to the overloaded glucose metabolism while utilizing lipid stores for energy production.

Site-Specific Hydrogen Isotope Composition of Propane: Mass spectrometric methods, equilibrium temperature dependence, and kinetics of exchange

Science.gov (United States)

Xie, H.; Ponton, C.; Kitchen, N.; Lloyd, M. K.; Lawson, M.; Formolo, M. J.; Eiler, J. M.

2016-12-01

Intramolecular isotope ordering can constrain temperatures of synthesis, mechanisms of formation, and/or source substrates of organic compounds. Here we explore site-specific hydrogen isotope variations of propane. Statistical thermodynamic models predict that at equilibrium methylene hydrogen (-CH2-) in propane will be 10's of per mil higher in D/H ratio than methyl hydrogen (-CH3) at geologically relevant temperatures, and that this difference is highly temperature dependent ( 0.5-1 ‰/°C). Chemical-kinetic controls on site-specific D/H in propane could constrain the mechanisms, conditions and extents of propane synthesis or destruction. We have developed a method for measuring the difference in D/H ratio between methylene and methyl hydrogen in propane by gas source mass spectrometry. The data were measured using the Thermo Fisher Double Focusing Sector high resolution mass spectrometer (DFS), and involve comparison of the D/H ratios of molecular ion (C3H8+) and the ethyl fragmental ion (C2H5+). We demonstrate the accuracy and precision of this method through analysis of D-labeled and independently analyzed propanes. In the exchange experiments, propane was heated (100-200 oC) either alone or in the presence of D-enriched water (δD=1,1419 ‰ SMOW), with or without one of several potentially catalytic substrates for hours to weeks. Propane was found to exchange hydrogen with water vigorously at 200 °C in the presence of metal catalysts. In the presence of Ni catalyst, methylene hydrogen exchanges 2.5 times faster than methyl hydrogen. Hydrogen exchange in the presence of Pd catalyst is more effective and can equilibrate hydrogen isotope distribution on propane on the order of 7 days. Isotopic exchange in the presence of natural materials have also been tested, but is only measurable in the methylene group at 200 °C. High catalytic activity of Pd permits attainment of a bracketed, time-invariant equilibrium state that we use to calibrate the site

Alkaline sodium borohydride gel as a hydrogen source for PEMFC or an energy carrier for NaBH 4-air battery

Science.gov (United States)

Liu, B. H.; Li, Z. P.; Chen, L. L.

In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH 4 gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH 4 concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl 2 catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH 4 gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH 4 solution. The NaBH 4 gel also successfully powered a NaBH 4-air battery.

Study of structural, surface and hydrogen storage properties of boric acid mediated metal (sodium)-organic frameworks

Science.gov (United States)

Ozer, Demet; Köse, Dursun A.; Sahin, Onur; Oztas, Nursen A.

2018-04-01

Three boric acid mediated metal organic frameworks were synthesized by solution method with using succinic acid, fumaric acid and acetylene dicarboxylic acid as a ligand source and sodium as a metal source. The complexes were characterized by FT-IR, powder XRD, elemental analyses and single crystal measurements. The complexes with the formula, C4H18B2Na2O14, C4H16B2Na2O14 and C4H14B2Na2O14 were successfully obtained. BET surface area of complexes were calculated and found as 13.474 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-succinato)-di-sodium boric acid solvate), 1.692 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-fumarato)-di-sodium boric acid solvate) and 5.600 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-acetylenedicarboxylato)-di-sodium boric acid solvate). Hydrogen storage capacities of the complexes were also studied at 77 K 1 bar pressure and found as 0.108%, 0.033%, 0.021% by mass. When different ligands were used, the pore volume, pore width and surface area of the obtained complexes were changed. As a consequence, hydrogen storage capacities also changed.

Ni(0-CMC-Na Nickel Colloids in Sodium Carboxymethyl-Cellulose: Catalytic Evaluation in Hydrogenation Reactions

Directory of Open Access Journals (Sweden)

Abdallah Karim

2011-01-01

Full Text Available A recyclable catalyst, Ni(0-CMC-Na, composed of nickel colloids dispersed in a water soluble bioorganic polymer, sodium carboxymethylcellulose (CMC-Na, was synthesized by a simple procedure from readily available reagents. The catalyst thus obtained is stable and highly active in alkene hydrogenations.

Inhibition of Enzymatic Browning of Chlorogenic Acid by Sulfur-Containing Compounds

NARCIS (Netherlands)

Kuijpers, T.F.M.; Narvaez Cuenca, C.E.; Vincken, J.P.; Verloop, J.W.; Berkel, van W.J.H.; Gruppen, H.

2012-01-01

The antibrowning activity of sodium hydrogen sulfite (NaHSO3) was compared to that of other sulfur-containing compounds. Inhibition of enzymatic browning was investigated using a model browning system consisting of mushroom tyrosinase and chlorogenic acid (5-CQA). Development of brown color

A Study on Renin-Angiotensin System and Total Exchangeable Sodium in Hypertension

International Nuclear Information System (INIS)

Choe, Kang Won; Park, Jung Sik; Lee, Jung Sang; Koh, Chang Soon

1976-01-01

The etiologic role of renin-angiotensin system and sodium-volume status in the pathophysiology of various forms of hypertension was investigated. Plasma renin activity (PRA) was measured by radioimmunoassay, while sodium-volume status was evaluated by the determination of total exchangeable sodium(NaE) using isotope dilution method. The subjects consisted of 25 controls, 24 patients with essential hypertension, 22 patients with chronic renal failure (13 with hypertension, 9 without hypertension) and 14 patients with malignant hypertension. The results were as follows: 1) An inverse correlation between NaE and PRA was noted in control subjects (r=-0.598, p 0.1) 3) Absolute value of PRA was not deviated significantly from control group (2.53±1.416 ng/ml/hr) except in malignant hypertension (6.09±2.042, p 0.1). It is suggested that renin-angiotensin system plays a predominant role in the pathogenesis of malignant hypertension and in hypertension of chronic renal failure, though sodium retention is also contributing factor. PRA variation in essential hypertension does not appear to be associated with any consistent change in Na-volume status, suggesting the existence of another mechanism in the genesis of hypertension and PRA variation.

Generation of Hydrogen, Lignin and Sodium Hydroxide from Pulping Black Liquor by Electrolysis

Directory of Open Access Journals (Sweden)

Guangzai Nong

2015-12-01

Full Text Available Black liquor is generated in Kraft pulping of wood or non-wood raw material in pulp mills, and regarded as a renewable resource. The objective of this paper was to develop an effective means to remove the water pollutants by recovery of both lignin and sodium hydroxide from black liquor, based on electrolysis. The treatment of a 1000 mL of black liquor (122 g/L solid contents consumed 345.6 kJ of electric energy, and led to the generation of 30.7 g of sodium hydroxide, 0.82 g of hydrogen gas and 52.1 g of biomass solids. Therefore, the recovery ratios of elemental sodium and biomass solids are 80.4% and 76%, respectively. Treating black liquor by electrolysis is an environmentally friendly technology that can, in particular, be an alternative process in addressing the environmental issues of pulping waste liquor to the small-scale mills without black liquor recovery.

Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

Science.gov (United States)

Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

2012-01-01

A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H2 mol−1 catalyst h−1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells. PMID:22953041

Heterogeneously catalyzed deuterium separation processes: Hydrogen-water exchange studies at elevated temperatures and pressures

International Nuclear Information System (INIS)

Halliday, J.D.; Rolston, J.H.; Au, J.C.; Den Hartog, J.; Tremblay, R.R.

1985-01-01

New processes for the separation of hydrogen isotopes are required to produce heavy water for CANDU nuclear reactors and to extract tritium formed in the moderator during reactor operation. Wetproofed platinum catalysts capable of promoting rapid exchange of isotopes between countercurrent flows of hydrogen and liquid water in packed columns have been developed at CRNL over the past 15 years. These catalysts provide a catalystic surface for the gas phase exchange reaction H/sub 2/O/sub (v)/ + HD/sub (g)/ ↔ HDO/sub (v)/ + H/sub 2(g)/ as well as a large liquid surface for the liquid phase isotope transfer reaction HDO/sub (v)/ + H/sub 2/O/sub (iota)/↔HDO/sub (iota)/+H/sub 2/O/sub (v)/. Any economic stand-alone heavy water separation process, based on bithermal hydrogen-water exchange over wetproofed platinum catalysts, requires rapid overall exchange of isotopes between two phases at two temperatures. Catalysts developed for cold tower operation at 25-60 0 C are now being tested in a laboratory scale stainless steel trickle bed reactor for performance and stability at simulated hot tower conditions, 150 0 C and 2.0 MPa pressure. Catalytically active layers containing platinum supported on carbon or crystalline silica and wetproofed with Teflon have been prepared on ceramic spheres and stainless steel screening and tested in both random and ordered bed columns

Methodology for Extraction of Remaining Sodium of Used Sodium Containers

International Nuclear Information System (INIS)

Jung, Minhwan; Kim, Jongman; Cho, Youngil; Jeong, Jiyoung

2014-01-01

Sodium used as a coolant in the SFR (Sodium-cooled Fast Reactor) reacts easily with most elements due to its high reactivity. If sodium at high temperature leaks outside of a system boundary and makes contact with oxygen, it starts to burn and toxic aerosols are produced. In addition, it generates flammable hydrogen gas through a reaction with water. Hydrogen gas can be explosive within the range of 4.75 vol%. Therefore, the sodium should be handled carefully in accordance with standard procedures even though there is a small amount of target sodium remainings inside the containers and drums used for experiment. After the experiment, all sodium experimental apparatuses should be dismantled carefully through a series of draining, residual sodium extraction, and cleaning if they are no longer reused. In this work, a system for the extraction of the remaining sodium of used sodium drums has been developed and an operation procedure for the system has been established. In this work, a methodology for the extraction of remaining sodium out of the used sodium container has been developed as one of the sodium facility maintenance works. The sodium extraction system for remaining sodium of the used drums was designed and tested successfully. This work will contribute to an establishment of sodium handling technology for PGSFR. (Prototype Gen-IV Sodium-cooled Fast Reactor)

Solubility of hydrogen in aqueous solutions of sodium and potassium bicarbonate from 293 to 333 K

NARCIS (Netherlands)

Engel, D.C.; Engel, D.C.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

1996-01-01

An experimental study is presented of the hydrogen solubility in aqueous salt solutions containing sodium and potassium bicarbonate from 293 to 333 K. For this purpose, gas consumption measurements have been performed by determining the ultimate pressure decrease in an intensively stirred, high

Solubility of Hydrogen in Aqueous Solutions of Sodium and Potassium Bicarbonate from 293 to 333 K

NARCIS (Netherlands)

Engel, Dico C.; Versteeg, Geert F.; Swaaij, Wim P.M. van

1996-01-01

An experimental study is presented of the hydrogen solubility in aqueous salt solutions containing sodium and potassium bicarbonate from 293 to 333 K. For this purpose, gas consumption measurements have been performed by determining the ultimate pressure decrease in an intensively stirred, high

Investigation of Plugging of Narrow Sodium Channels by Sodium and Carbon Dioxide Interaction

Energy Technology Data Exchange (ETDEWEB)

Park, Sun Hee; Wi, Myung-Hwan; Min, Jae Hong; Kim, Tae-joon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

The supercritical CO{sub 2} Brayton cycle system is known to be a promising power conversion system for improving the efficiency and preventing the sodium water reaction (SWR) of the current SFR concept using a Rankine steam cycle. PCHEs are known to have potential for reducing the volume occupied by the sodium-to-CO{sub 2} exchangers as well as the heat exchanger mass relative to traditional shell-and-tube heat exchangers. Here, we report a study on a plugging test by the interaction of sodium and CO{sub 2} to investigate design parameters of sodium channels in the realistic operating conditions. We investigated a plugging test by an interaction of sodium and CO{sub 2} with different cross sectional areas of the sodium channels. It was found that the flow rate of sodium decreased earlier and faster with a narrower cross sectional area compared to a wider one. Our experimental results are expected to be used for determining the sodium channel areas of PCHEs.

Proton NMR investigation of heme pocket mobility in hemoglobin via hydrogen isotope exchange kinetics

International Nuclear Information System (INIS)

Han, K.

1985-01-01

Dynamic mobility of heme cavity, the active site of Hb, was investigated by analyzing the hydrogen isotope exchange kinetics of the proximal histidyl ring NH of various kinds of Hbs with the aid of the high field Fourier Transform 1 H NMR spectroscopy. The exchange reaction occurs faster in oxy or R-state Hb than in deoxy or T-state Hb and there exists a good correlation between the oxygen affinity of Hb and the heme pocket mobility reflected in the hydrogen exchange rate. The effect of pH on the exchange is dramatically different for the two subunits of Hb A. Studying the exchange characteristics of mutant Hbs and chemically modified Hbs not only showed the existence of three well-defined localized paths for transmission of conformational changes between different heme pockets through a 1 b 2 subunit interface, but also indicated that the heme pocket mobility is regulated by the quaternary state of Hb as well as by the ligation state of Hb. Finally, the effect of the quaternary state on the heme pocket mobility is separated from that of the ligation by following the exchange reactions in Hbs where only their quaternary structure transition can be achieved without changing their ligation states by adjusting experimental conditions such as adding inositol hexaphosphate

Preparation of Li4Ti5O12 by solution ion-exchange of sodium titanate nanotube and evaluation of electrochemical performance

International Nuclear Information System (INIS)

Zhang, Jingwei; Zhang, Fenli; Li, Jiuhe; Cai, Wei; Zhang, Jiwei; Yu, Laigui; Jin, Zhensheng; Zhang, Zhijun

2013-01-01

Nano-sized spinel lithium titanate (Li 4 Ti 5 O 12 ) was synthesized using sodium titanate nanotube as precursor via a facile solution ion-exchange method in association with subsequent calcination treatment at relatively low temperature. The influences of precursors, ion-exchange condition, and calcination temperature on the microstructure and electrochemical performance of the products were studied. Results indicate that pure-phase Li 4 Ti 5 O 12 can be harvested from sodium titanate nanotube precursor through an ion-exchanging at room temperature and calcination at 500 °C. The products exhibit a better performance as Li-ion battery anode material than the counterparts prepared from protonic titanate nanotube (H-titanate) precursor. The reason may lie in that sodium titanate nanotube is easier than protonic titanate nanotube to synthesize lithium titanate without TiO 2 impurity, resulting in reduced electron transfer ability and Li-ion transport ability. The capacity of Li 4 Ti 5 O 12 prepared from sodium titanate nanotube is 146 mAh/g at 10 C, and it has only 0.7 % decay after 200 charge/discharge cycles

The inhibitive action of sodium castor sulphonate Towards the corrosion of aluminium in Hydrochloric acid

OpenAIRE

Soliman, S.A.; Mourad, M. Y.

1993-01-01

The dissolution of aluminium in 2M HC1 solution in presence of sodium castor sulphonate (SCS) has been studied using thermometric and hydrogen evolution methods. The results showed that the additive retards the dissolution due to its chemisorption on the metal surface via 71 the electrons of the double bond. The inhibition obyes the Frumkin's isotherm. تمت دراسة ذوبان فلز الألمنيوم في محلول 2 مولاري من حمض الهيدروكلوريك في وجود سلفونات الخروع الصوديومية باستخدام الطريقة الحرارية وطريقة تص...

Erosion-inhibiting effect of sodium fluoride and titanium tetrafluoride treatment in vitro

NARCIS (Netherlands)

Rijkom, Hans van; Ruben, J.; Vieira, A.; Huysmans, M.C.; Truin, G-J.; Mulder, J.

2003-01-01

The prevention of dental erosion with fluoride is still largely unknown territory. It was the aim of this study to determine the erosion-inhibiting effect of topical neutral 1% sodium fluoride (NaF) application and an application of a 4% titanium tetrafluoride (TiF4) solution compared with no

Isotopic modeling of water and sodium distribution and exchange kinetics in 7 stable hemodialysis patients

International Nuclear Information System (INIS)

Chamoiseau, S.; Bertrou, L.; Pujo, J.M.; Massol, M.

1988-01-01

Sequential serum sampling over 24 h. has been performed in 7 hemodialysis patients after simultaneous intra-venous injection of tritiated water and 24 Na. Each time-activity curve fits a biexponential pattern. A compartment analysis leads to describe either a simple but incomplete single compartment model or a much more satisfactory open two-compartment mamillary model featuring 2 intercompartment transfer rate constants k 21 and k 12 , and a loss out of the system, k 01 . These constants can be related to intrabody resistances to sodium and water transfers. Compartment analysis allows a comprehensive quantitated description of the exchange and transfer kinetics of sodium and water throughout the system. Evidence for a sodium reservoir, probably located in bone, can be drawn from the results and leads to propose a strategy for a targetted bone sodium removal [fr

Effect of controlled deactivation on the thermochemical characteristics of hydrogen adsorption on skeletal nickel from sodium hydroxide-water solutions

Science.gov (United States)

Prozorov, D. A.; Lukin, M. V.; Ulitin, M. V.

2013-04-01

Differential heats of adsorption in a wide range of surface coverage and maximum amounts of adsorbed hydrogen are determined by adsorption calorimetry on partially deactivated skeletal nickel from aqueous solutions of sodium hydroxide. The effect of the composition of solutions on the values of limiting adsorption and adsorption equilibria of individual forms of hydrogen is shown.

The sodium-calcium exchanger is a mechanosensitive transporter.

Science.gov (United States)

Reeves, John P; Abdellatif, Maha; Condrescu, Madalina

2008-03-15

This report describes the influence of fluid flow and osmotically induced volume changes on Na(+)-Ca(2+) exchange (NCX) activity in transfected CHO cells. Exchange activity was measured as Na(+)-dependent Ca(2+) or Ba(2+) fluxes using the fluorescent probe fura-2. When exchange activity was initiated by superfusing Ba(2+)-containing solutions over the cells for a 20 s interval, a high rate of Ba(2+) uptake was observed while the solution was being applied but the rate of Ba(2+) uptake declined > 10-fold when the solution flow ceased. Ba(2+) efflux in exchange for extracellular Na(+) or Ca(2+) (Ba(2+)-Ca(2+) exchange) was similarly biphasic. During NCX-mediated Ca(2+) uptake, a rapid increase in cytosolic [Ca(2+)] to a peak value occurred, followed by a decline in [Ca(2+)](i) to a lower steady-state value after solution flow ceased. When NCX activity was initiated by an alternate procedure that minimized the duration of solution flow, the rapid phase of Ba(2+) influx was greatly reduced in magnitude and Ca(2+) uptake became nearly monophasic. Solution superfusion did not produce any obvious changes in cell shape or volume. NCX-mediated Ba(2+) and Ca(2+) influx were also sensitive to osmotically induced changes in cell volume. NCX activity was stimulated in hypotonic media and inhibited in hypertonic media; the osmotically induced changes in activity occurred within seconds and were rapidly reversible. We conclude that NCX activity is modulated by both solution flow and osmotically induced volume changes.

Tin and tin-titanium as catalyst components for reversible hydrogen storage of sodium aluminium hydride

Energy Technology Data Exchange (ETDEWEB)

Qi Jia Fu; Shik Chi Tsang [University of Reading, Reading (United Kingdom). Surface and Catalysis Research Centre, School of Chemistry

2006-10-15

This paper is concerned with the effects of adding tin and/or titanium dopant to sodium aluminium hydride for both dehydrogenation and re-hydrogenation reactions during their reversible storage of molecular hydrogen. Temperature programmed decomposition (TPD) measurements show that the dehydrogenation kinetics of NaAlH{sub 4} are significantly enhanced upon doping the material with 2 mol% of tributyltin hydride, Sn(Bu)3H but the tin catalyst dopant is shown to be inferior than titanium. On the other hand, in this preliminary work, a significant synergetic catalytic effect is clearly revealed in material co-doped with both titanium and tin catalysts which shows the highest reversible rates of dehydrogenation and re-hydrogenation (after their hydrogen depletion). The re-hydrogenation rates of depleted Sn/Ti/NaAlH{sub 4} evaluated at both 9.5 and 140 bars hydrogen are also found to be favourable compared to the Ti/NaAlH{sub 4}, which clearly suggest the importance of the catalyst choice. Basing on these results some mechanistic insights for the catalytic reversible dehydrogenation and re-hydrogenation processes of Sn/Ti/NaAlH{sub 4} are therefore made. 31 refs., 8 figs., 2 tabs.

Parathyroid hormone inhibition of Na{sup +}/H{sup +} exchanger 3 transcription: Intracellular signaling pathways and transcription factor expression

Energy Technology Data Exchange (ETDEWEB)

Neri, Elida Adalgisa; Bezerra, Camila Nogueira Alves, E-mail: camilab@icb.usp.br; Queiroz-Leite, Gabriella Duarte; Polidoro, Juliano Zequini; Rebouças, Nancy Amaral

2015-06-12

The main transport mechanism of reabsorption of sodium bicarbonate and fluid in the renal proximal tubules involves Na{sup +}/H{sup +} exchanger 3 (NHE3), which is acutely and chronically downregulated by parathyroid hormone (PTH). Although PTH is known to exert an inhibitory effect on NHE3 expression and transcription, the molecular mechanisms involved remain unclear. Here, we demonstrated that, in opossum kidney proximal tubule (OKP) cells, PTH-induced inhibition of Nhe3 gene promoter occurs even in the core promoter that controls expression of the reporter gene. We found that inhibition of the protein kinase A (PKA) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways transformed PTH from an inhibitor of promoter activity into an activator of that same activity, as did point mutations in the EGR1, Sp1, and Sp3 binding consensus elements in the promoter. In nuclear extracts of PTH-treated OKP cells, we also observed increased expression of EGR1 mRNA and of some Sp3 isoforms. Electrophoretic mobility shift assay showed a supershift of the −61 to −42-bp probe with an anti-EGR1 antibody in PTH-treated cells, suggesting that EGR1 binding is relevant for the inhibitory activity of PTH. We conclude that PTH-induced inhibition of NHE3 transcription is related to higher EGR1 expression; to EGR1 binding to the proximal and core promoters; and to PKA and JAK/STAT pathway activation. This mechanism might be responsible, at least in part, for lower NHE3 expression and sodium reabsorption in renal proximal tubules in the presence of high PTH levels. - Highlights: • PTH regulation of Nhe3 promoter depends on EGR1 binding. • EGR1, PKA and JAK/STAT are involved in PTH inhibition of the Nhe3 promoter. • PTH alters expression of EGR1 and Sp3. • PTH inhibits the Nhe3 promoter by regulating PKA and JAK/STAT signaling.

Corrosion Inhibition by Sodium Gluconate-Zn2+-DTPMP System

Directory of Open Access Journals (Sweden)

P. Manjula

2009-01-01

Full Text Available The inhibition efficiency of a phosphonic acid, Diethylene Triamine Pentamethylene Phosphonic acid (DTPMP in controlling corrosion of carbon steel immersed in an aqueous solution containing 60 ppm of Cl- has been evaluated by weight loss method in the absence and presence of Zn2+. The formulation consisting of DTPMP and Zn2+ has excellent inhibition efficiency (IE. A synergistic effect is noticed between Zn2+ and DTPMP. Addition of sodium gluconate (SG enhances the IE of Zn2+ and DTPMP system. The DTPMP-Zn2+-SG system function as a mixed inhibitor as revealed by polarization study. AC impedance spectrum, optical and atomic force micrographs reveal the formation of a protective film on the metal surface. FTIR spectra reveal that the protective film consists of Fe2+-DTPMP complex, Fe2+-SG complex and Zn(OH2.

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

Directory of Open Access Journals (Sweden)

Jianfeng Mao

2015-01-01

Full Text Available The development of new practical hydrogen storage materials with high volumetric and gravimetric hydrogen densities is necessary to implement fuel cell technology for both mobile and stationary applications. NaBH4, owing to its low cost and high hydrogen density (10.6 wt%, has received extensive attention as a promising hydrogen storage medium. However, its practical use is hampered by its high thermodynamic stability and slow hydrogen exchange kinetics. Recent developments have been made in promoting H2 release and tuning the thermodynamics of the thermal decomposition of solid NaBH4. These conceptual advances offer a positive outlook for using NaBH4-based materials as viable hydrogen storage carriers for mobile applications. This review summarizes contemporary progress in this field with a focus on the fundamental dehydrogenation and rehydrogenation pathways and properties and on material design strategies towards improved kinetics and thermodynamics such as catalytic doping, nano-engineering, additive destabilization and chemical modification.

Isotopic studies on ligand exchange between complex and simple cyanides in water medium and in liquid hydrogen cyanide. Part 2. Radiocyanide ligand exchange study between hydrogen cyanide and octacyanotungstate(4) in water solutions of mineral acids

International Nuclear Information System (INIS)

Zielinski, M.

1979-01-01

Radiocyanide ligand exchange between potassium octacyanotungstate(4) and hydrogen cyanide in aqueous solutions of sulfuric acid and between octacyanotungstic(4) acid and hydrogen cyanide in aqueous solutions have been investigated experimentally. The observed enhancement of the rate of ligand exchange in acidic medium has been rationalized in terms of the proposed new general reaction scheme taking into account the reversible decomposition of complex cyanide at low pH, and irreversible one at high pH. The discussion on the results obtained has been carried out within the framework of derived formal kinetic equations. (author)

A Simulation Study of Inter Heat Exchanger Process in SI Cycle Process for Hydrogen Production

International Nuclear Information System (INIS)

Shin, Jae Sun; Cho, Sung Jin; Choi, Suk Hoon; Qasim, Faraz; Lee, Euy Soo; Park, Sang Jin; Lee, Heung N.; Park, Jae Ho; Lee, Won Jae

2014-01-01

SI Cyclic process is one of the thermochemical hydrogen production processes using iodine and sulfur for producing hydrogen molecules from water. VHTR (Very High Temperature Reactor) can be used to supply heat to hydrogen production process, which is a high temperature nuclear reactor. IHX (Intermediate Heat Exchanger) is necessary to transfer heat to hydrogen production process safely without radioactivity. In this study, the strategy for the optimum design of IHX between SI hydrogen process and VHTR is proposed for various operating pressures of the reactor, and the different cooling fluids. Most economical efficiency of IHX is also proposed along with process conditions

DeVelopment of the high-intensity polarized H- source with proton charge exchange on sodium optically oriented atoms

International Nuclear Information System (INIS)

Zelenskij, A.N.; Kokhanovskij, S.A.

1982-01-01

The results of experimental study on the source of polarized H - ions at polarized electron capture by proton from optically oriented sodium atoms are presented. Circular-polarized dye laser radiation with lamp pumping is used for polarization of highly dense sodium vapors in the pulsed mode. A facility for polarization measurement in the ion source is described. Dependence of the counting rate of metastables for the right and left circular radiation polarization in respect to wave length is presented. The results of measuring the degree of polarization under change of sodium density are revealed. The measurements have disclosed that obtaining of high polarization degree at 20-30% charge exchange effectiveness is possible but large radiation power is required. Use of a dense charge exchange target provides high effectiveness of hte whole polarization process. Yield of polarized H - ions can approach 10 μA/1 mA of the initial proton current

Experimental evaluation of improved dual temperature hydrogen isotopic exchange reaction system

International Nuclear Information System (INIS)

Asakura, Yamato; Uchida, Shunsuke

1984-01-01

A proposed dual temperature hydrogen isotopic exchange reaction system between water and hydrogen gas is evaluated experimentally. The proposed system is composed of low temperature co-current reactors for reaction between water mists and hydrogen gas and high temperature co-current reactors for reaction between water vapor and hydrogen gas. Thus, operation is possible under atmospheric pressure with high reaction efficiency. Using the pilot test system which is composed of ten low temperature (30 0 C) reaction units and ten high temperature (200 0 C) reaction units, an experimental separation of deuterium from light water is carried out. The enrichment factor under steady state conditions, its dependency on operating time, and the reaction period necessary to obtain the steady state enrichment factor are determined experimentally and compared with calculations. It is shown that separation ability in a multistage reaction system can be estimated by numerical calculation using actual reaction efficiency in a unit reactor. (author)

Thermometric titration of cadmium with sodium diethyldithiocarbamate, with oxidation by hydrogen peroxide as indicator reaction.

Science.gov (United States)

Hattori, T; Yoshida, H

1987-08-01

A new method of end-point indication is described for thermometric titration of cadmium with sodium diethyldithiocarbamate (DDTC). It is based on the redox reaction between hydrogen peroxide added to the system before titration, and the first excess of DDTC. Amounts of cadmium in the range 10-50 mumoles are titrated within 1% error.

Gaseous anion chemistry. Hydrogen-deuterium exchange in mono- and dialcohol alkoxide ions: ionization reactions in dialcohols

International Nuclear Information System (INIS)

Lloyd, J.R.; Agosta, W.C.; Field, F.H.

1980-01-01

The subject of this work is H-D exchange in certain gaseous anions using D 2 as the exchanging agent. The anions involved are produced from ethylene glycol, 1,3-propanediol, 1,4-butanediol, ethanol, 1-propanol, and 1-butanol. Spectra and postulated ionization reactions for these mono- and dialcohols are given. Hydrogen-deuterium exchange occurs in the (M - 1) - and (2M - 1) - ions of ethylene glycol, 1,3-propanediol, and 1,4-butanediol. The amount of exchange occurring is 3-8 times greater in (2M - 1) - than in (M - 1) - . The amount of H-D exchange occurring in ethanol, 1-propanol, and 1-butanol is small or zero in the (2M - 1) - ions and in the (M - 1) - ion for 1-butanol [the only (M - 1) - ion which could be examined experimentally]. The amount of exchange occurring in the (2M - 1) - and (M - 1) - ions from ethylene glycol is not affected by the total pressure or composition of the reaction mixture in the ionization chamber of the mass spectrometer. A novel hydrogen-bridging mechanism is suggested to account for the observed exchange occurring in the dialcohols

Alkaline sodium borohydride gel as a hydrogen source for PEMFC or an energy carrier for NaBH{sub 4}-air battery

Energy Technology Data Exchange (ETDEWEB)

Liu, B.H. [Department of Materials and Engineering, Zhejiang University (China); Li, Z.P.; Chen, L.L. [Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China)

2008-05-15

In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH{sub 4} gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH{sub 4} concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl{sub 2} catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH{sub 4} gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH{sub 4} solution. The NaBH{sub 4} gel also successfully powered a NaBH{sub 4}-air battery. (author)

Ortho-para-H2 conversion by hydrogen exchange: comparison of theory and experiment.

Science.gov (United States)

Lique, François; Honvault, Pascal; Faure, Alexandre

2012-10-21

We report fully-quantum time-independent calculations of cross sections and rate coefficients for the collisional (de)excitation of H(2) by H. Our calculations are based on the H(3) global potential energy surface of Mielke et al. [J. Chem. Phys. 116, 4142 (2002)]. The reactive hydrogen exchange channels are taken into account. We show that the ortho-para and para-ortho conversion of H(2) are significant processes at temperatures above ~300 K and for the last process we provide the first comparison with available experimental rate coefficients between 300 and 444 K. The good agreement between theory and experiment is a new illustration of our detailed understanding of the simplest chemical reaction. The importance of the ortho-para-H(2) conversion by hydrogen exchange in astrophysics is discussed.

Destruction of gel sulfonated cation-exchangers of the KU-2 type under the influence of hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Roginskaya, B.S.; Zavadovskaya, A.S.; Znamenskii, Yu.P.; Paskhina, N.A.; Dobrova, E.I.

1988-10-20

The purpose of this work was to study the mechanism of interaction of Soviet sulfonated cation-exchangers of the KU-2 type with hydrogen peroxide. It is shown that under the influence of hydrogen peroxide sulfonated cation-exchangers begin, after a certain induction period, to lose capacity and to release destruction products into water; the length of the induction period increases with the degree of cross-linking. In a given time of contact between the resin and the solution the degree of destruction falls with increase of cross-linking. The principal product of destruction of sulfonated cation-exchangers is an aromatic sulfonic acid containing oxidized groups in the side chains.

Hydrogen meter prooftesting

International Nuclear Information System (INIS)

McCown, J.J.; Mettler, G.W.

1976-04-01

Two diffusion type hydrogen meters have been tested on the Prototype Applications Loop (PAL). The ANL designed unit was used to monitor hydrogen in sodium during FFTF startup and over a wide range of hydrogen concentrations resulting from chemical additions to the sodium and cover gas. A commercially available meter was added and its performance compared with the ANL unit. Details of the test work are described

Hydrogen substituted graphdiyne as carbon-rich flexible electrode for lithium and sodium ion batteries.

Science.gov (United States)

He, Jianjiang; Wang, Ning; Cui, Zili; Du, Huiping; Fu, Lin; Huang, Changshui; Yang, Ze; Shen, Xiangyan; Yi, Yuanping; Tu, Zeyi; Li, Yuliang

2017-10-27

Organic electrodes are potential alternatives to current inorganic electrode materials for lithium ion and sodium ion batteries powering portable and wearable electronics, in terms of their mechanical flexibility, function tunability and low cost. However, the low capacity, poor rate performance and rapid capacity degradation impede their practical application. Here, we concentrate on the molecular design for improved conductivity and capacity, and favorable bulk ion transport. Through an in situ cross-coupling reaction of triethynylbenzene on copper foil, the carbon-rich frame hydrogen substituted graphdiyne film is fabricated. The organic film can act as free-standing flexible electrode for both lithium ion and sodium ion batteries, and large reversible capacities of 1050 mAh g -1 for lithium ion batteries and 650 mAh g -1 for sodium ion batteries are achieved. The electrode also shows a superior rate and cycle performances owing to the extended π-conjugated system, and the hierarchical pore bulk with large surface area.

Lactulose mediates suppression of dextran sodium sulfate-induced colon inflammation by increasing hydrogen production.

Science.gov (United States)

Chen, Xiao; Zhai, Xiao; Shi, Jiazi; Liu, Wen Wu; Tao, Hengyi; Sun, Xuejun; Kang, Zhimin

2013-06-01

Molecular hydrogen (H2) is a potent antioxidant and able to protect organs from oxidative stress injuries. Orally administered lactulose, a potent H2 inducer, is digested by colon microflora and significantly increases H2 production, indicating its potential anti-inflammatory action. To evaluate the anti-inflammatory effects of lactulose on dextran sodium sulfate (DSS)-induced colitis in mice. Mice were randomly assigned into seven groups, receiving regular distilled water, H2-rich saline (peritoneal injection), DSS, oral lactulose (0.1, 0.15, 0.2 ml/10 g, respectively), and lactulose (0.2 ml/10 g) + oral antibiotics. The mouse model of human ulcerative colitis was established by supplying mice with water containing DSS. The H2 breath test was used to determine the exhaled H2 concentration. Body weight, colitis score, colon length, pathological features and tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), maleic dialdehyde (MDA) and marrow peroxidase (MPO) levels in colon lesions were evaluated. After 7 days, DSS-induced loss of body weight, increase of colitis score, shortening of colon length, pathological changes and elevated levels of TNF-α, IL-1β, MDA, and MPO in colon lesions, were significantly suppressed by oral lactulose administration and intraperitoneally injected H2-rich saline. Ingestion of antibiotics significantly compromised the anti-inflammatory effects of lactulose. The H2 breath test showed that lactulose administration significantly induced hydrogen production and that antibiotics administration could inhibit H2 production. Lactulose can prevent the development of DSS-induced colitis and alleviate oxidative stress in the colon, as measured by MDA and MPO, probably by increasing endogenous H2 production.

Study of the inhibition of respiration/fermentation in yeast cells by sodium fluoride

Directory of Open Access Journals (Sweden)

López Pérez, José Pedro

2013-01-01

Full Text Available This paper presents the necessary guidelines to achieve the observation of the inhibition of sugar metabolism in yeast cells by means of the compound sodium fluoride. This activity is appropriate for the subject of Biology in Secondary Education as well as High School.

Analysis and test of a breadboard cryogenic hydrogen/Freon heat exchanger

Science.gov (United States)

Desjardins, L. F.; Hooper, J.

1973-01-01

System studies required to verify a tube-in-tube cryogenic heat exchanger as optimum for the space shuttle mission are described. Design of the optimum configuration, which could be fabricated from commercially available hardware, is discussed. Finally, testing of the proposed configuration with supercritical hydrogen and Freon 21 is discussed and results are compared with thermal and dynamic analysis.

Numerical study on pressure drop and heat transfer for designing sodium-to-air heat exchanger tube banks on advanced sodium-cooled fast reactor

International Nuclear Information System (INIS)

Kang, Hie-Chan; Eoh, Jae-Hyuk; Cha, Jae-Eun; Kim, Seong-O.

2013-01-01

Highlights: ► Numerical simulation for the heat flow characteristic of the sodium-to-air heat exchanger (AHX) and tube banks. ► Parallelogram tube banks showed almost similar thermal and hydraulic characteristics to the rectangular tube banks. ► Pressure drop and heat transfer of the staggered and rectangular tube banks compared with Zhukauskas’ correlation. ► AHX was modeled as porous media and suggested design guide to enhance the performance. - Abstract: A numerical study is performed to investigate the thermal and hydraulic characteristics and build up design model of the AHX (sodium-to-air heat exchanger) unit of a sodium-cooled fast reactor. Helical-coiled tube banks in the AHX are modeled as porous media and simulated heat and momentum transfer by a commercial program. Two-dimensional flow characteristic appears differently at the inlet region of the AHX annulus, and the required length of the inlet region is shorter for an inlet having a 45 degree chamber or a round shape than for one with a perpendicular corner. Pressure drop and heat transfer coefficient for rectangular, parallelogram and staggered tube banks as the main components of the AHX are evaluated and discussed. Pressure drop and heat transfer shows similar trends and underestimated values, respectively, when compared with Zhukauskas empirical correlations. The parallelogram tube bank shows similar results to the rectangular arrangement.

Amide proton solvent protection in amylin fibrils probed by quenched hydrogen exchange NMR.

Directory of Open Access Journals (Sweden)

Andrei T Alexandrescu

Full Text Available Amylin is an endocrine hormone that accumulates in amyloid plaques in patients with advanced type 2 diabetes. The amyloid plaques have been implicated in the destruction of pancreatic β-cells, which synthesize amylin and insulin. To better characterize the secondary structure of amylin in amyloid fibrils we assigned the NMR spectrum of the unfolded state in 95% DMSO and used a quenched hydrogen-deuterium exchange technique to look at amide proton solvent protection in the fibrils. In this technique, partially exchanged fibrils are dissolved in 95% DMSO and information about amide proton occupancy in the fibrils is determined from DMSO-denatured monomers. Hydrogen exchange lifetimes at pH 7.6 and 37°C vary between ∼5 h for the unstructured N-terminus to 600 h for amide protons in the two β-strands that form inter-molecular hydrogen bonds between amylin monomers along the length of the fibril. Based on the protection data we conclude that residues A8-H18 and I26-Y37 comprise the two β-strands in amylin fibrils. There is variation in protection within the β-strands, particularly for strand β1 where only residues F15-H18 are strongly protected. Differences in protection appear to be due to restrictions on backbone dynamics imposed by the packing of two-layers of C2-symmetry-related β-hairpins in the protofilament structure, with strand β1 positioned on the surface and β2 in the interior.

Liquid-phase chemical hydrogen storage: catalytic hydrogen generation under ambient conditions.

Science.gov (United States)

Jiang, Hai-Long; Singh, Sanjay Kumar; Yan, Jun-Min; Zhang, Xin-Bo; Xu, Qiang

2010-05-25

There is a demand for a sufficient and sustainable energy supply. Hence, the search for applicable hydrogen storage materials is extremely important owing to the diversified merits of hydrogen energy. Lithium and sodium borohydride, ammonia borane, hydrazine, and formic acid have been extensively investigated as promising hydrogen storage materials based on their relatively high hydrogen content. Significant advances, such as hydrogen generation temperatures and reaction kinetics, have been made in the catalytic hydrolysis of aqueous lithium and sodium borohydride and ammonia borane as well as in the catalytic decomposition of hydrous hydrazine and formic acid. In this Minireview we briefly survey the research progresses in catalytic hydrogen generation from these liquid-phase chemical hydrogen storage materials.

Experimental determination of reaction rates of water. Hydrogen exchange of tritium with hydrophobic catalysts

International Nuclear Information System (INIS)

Bixel, J.C.; Hartzell, B.W.; Park, W.K.

1976-01-01

This study was undertaken to obtain data needed for further development of a process for the enrichment and removal of tritium from the water associated with light-water reactors, fuel-reprocessing plants, and tritium-handling laboratories. The approach is based on the use of antiwetting, hydrophobic catalysts which permit the chemical exchange reactions between liquid water and gaseous hydrogen in direct contact, thus eliminating problems of catalyst deactivation and the complexity of reactor design normally associated with current catalytic-detritiation techniques involving gas-phase catalysis. An apparatus and procedure were developed for measuring reaction rates of water-hydrogen chemical exchange with hydrophobic catalysts. Preliminary economic evaluations of the process were made as it might apply to the AGNS fuel reprocessing plant

Gaseous exchange reaction of deuterium between hydrogen and water on hydrophobic catalyst supporting platinum

International Nuclear Information System (INIS)

Izawa, Hirozumi; Isomura, Shohei; Nakane, Ryohei.

1979-01-01

The deuterium exchange reaction between hydrogen and water in the gas phase where the fed hydrogen gas is saturated with water vapor is studied experimentally by use of the proper hydrophobic catalysts supporting platinum. It is found that the activities of those catalysts for this reaction system are very high compared with the other known ones for the systems in which gas and liquid should coexist on catalyst surfaces, and that the apparent catalytic activity becomes larger as the amount of platinum supported on a catalyst particle increases. By analyses of the data the following informations are obtained. The exchange reaction can be expressed by a first order reversible reaction kinetics. The pore diffusion in the catalyst particles has significant effect on the overall reaction mechanisms. (author)

Comparison of Methods for Computing the Exchange Energy of quantum helium and hydrogen

International Nuclear Information System (INIS)

Cayao, J. L. C. D.

2009-01-01

I investigate approach methods to find the exchange energy for quantum helium and hydrogen. I focus on Heitler-London, Hund-Mullikan, Molecular Orbital and variational approach methods. I use Fock-Darwin states centered at the potential minima as the single electron wavefunctions. Using these we build Slater determinants as the basis for the two electron problem. I do a comparison of methods for two electron double dot (quantum hydrogen) and for two electron single dot (quantum helium) in zero and finite magnetic field. I show that the variational, Hund-Mullikan and Heitler-London methods are in agreement with the exact solutions. Also I show that the exchange energy calculation by Heitler-London (HL) method is an excellent approximation for large inter dot distances and for single dot in magnetic field is an excellent approximation the Variational method. (author)

Water-Protein Hydrogen Exchange in the Micro-Crystalline Protein Crh as Observed by Solid State NMR Spectroscopy

International Nuclear Information System (INIS)

Boeckmann, Anja; Juy, Michel; Bettler, Emmanuel; Emsley, Lyndon; Galinier, Anne; Penin, Francois; Lesage, Anne

2005-01-01

We report site-resolved observation of hydrogen exchange in the micro-crystalline protein Crh. Our approach is based on the use of proton T 2 ' -selective 1 H- 13 C- 13 C correlation spectra for site-specific assignments of carbons nearby labile protein protons. We compare the proton T 2 ' selective scheme to frequency selective water observation in deuterated proteins, and discuss the impacts of deuteration on 13 C linewidths in Crh. We observe that in micro-crystalline proteins, solvent accessible hydroxyl and amino protons show comparable exchange rates with water protons as for proteins in solution, and that structural constraints, such as hydrogen bonding or solvent accessibility, more significantly reduce exchange rates

Sodium current inhibition by nanosecond pulsed electric field (nsPEF)--fact or artifact?

NARCIS (Netherlands)

Verkerk, Arie O.; van Ginneken, Antoni C. G.; Wilders, Ronald

2013-01-01

In two recent publications in Bioelectromagnetics it has been demonstrated that the voltage-gated sodium current (I(Na)) is inhibited in response to a nanosecond pulsed electric field (nsPEF). At the same time, there was an increase in a non-inactivating "leak" current (I(leak)), which was

Sodium glucose transporter 2 (SGLT2 inhibition and ketogenesis

Directory of Open Access Journals (Sweden)

Sanjay Kalra

2015-01-01

Full Text Available Sodium glucose transporter 2 (SGLT2 inhibitors are a recently developed class of drug that have been approved for use in type 2 diabetes. Their unique extra-pancreatic glucuretic mode of action has encouraged their usage in type 1 diabetes as well. At the same time, reports of pseudo ketoacidosis and ketoacidosis related to their use have been published. No clear mechanism for this phenomenon has been demonstrated so far. This communication delves into the biochemical effects of SGLT2 inhibition, discusses the utility of these drugs and proposes steps to maximize safe usage of the molecules.

Novel silica-based ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

Alkali free hydrolysis of sodium borohydride for hydrogen generation under pressure

Energy Technology Data Exchange (ETDEWEB)

Ferreira, M.J.F.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gales, L. [Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto and Instituto de Ciencias Biomedicas Abel Salazar, Largo Prof. Abel Salazar 2, 4099-003 Porto (Portugal); Fernandes, V.R.; Rangel, C.M. [Laboratorio Nacional de Energia e Geologia - LNEG, Fuel Cells and Hydrogen Unit Estrada do Paco do Lumiar 22, 1649-038 Lisboa (Portugal)

2010-09-15

The present study is related with the production of hydrogen gas (H{sub 2}), at elevated pressures and with high gravimetric storage density, to supply a PEM fuel cell on-demand. To achieve this goal, solid sodium borohydride (NaBH{sub 4}) was mixed with a proper amount of a powder reused nickel-ruthenium based catalyst (Ni-Ru based/NaBH{sub 4}: 0.2 and 0.4 g/g; {approx}150 times reused) inside the bottom of a batch reactor. Then, a stoichiometric amount of pure liquid water (H{sub 2}O/NaBH{sub 4}: 2-8 mol/mol) was added and the catalyzed NaBH{sub 4} hydrolysis evolved, in the absence of an alkali inhibitor. In this way, this research work is designated alkali free hydrolysis of NaBH{sub 4} for H{sub 2} generation. This type of hydrolysis is excellent from an environmental point of view because it does not involve strongly caustic solutions. Experiments were performed in three batch reactors with internal volumes 646, 369 and 229 cm{sup 3}, and having different bottom geometries (flat and conical shapes). The H{sub 2} generated was a function of the added water and completion was achieved with H{sub 2}O/NaBH{sub 4} = 8 mol/mol. The results show that hydrogen yields and rates increase remarkably increasing both system temperature and pressure. Reactor bottom shape influences deeply H{sub 2} generation: the conical bottom shape greatly enhances the rate and practically eliminates the reaction induction time. Our system of compressed hydrogen generation up to 1.26 MPa shows 6.3 wt% and 70 kg m{sup -3}, respectively, for gravimetric and volumetric hydrogen storage capacities (materials-only basis) and therefore is a viable hydrogen storage candidate for portable applications. (author)

Hydrogen transfer preventive device in FBR power plant

International Nuclear Information System (INIS)

Hoshi, Yuichi.

1987-01-01

Purpose: To prevent transfer of hydrogen, etc. in FBR power plant. Constitution: Since H 2 permeates heat conduction pipes in a steam generator, it is necessary to eliminate all of permeation hydrogen, etc. by primary cold traps particularly in the case of saving the intermediate heat exchange. In view of the above, the heat conduction pipes of the steam generator are constituted as a double pipe structure and helium gases are recycled through the gaps thereof and hydrogen traps are disposed to the recycling path. H 2 released into water flowing through the inside of the inner pipe is permeated through the inner pipe and leached into the gap, but the leached H 2 is carried by the helium recycling stream to the hydrogen trap and then the H 2 stream removed with H 2 is returned to the gaps. In this way, the capacity of the primary cold traps disposed in the liquid sodium recycling circuit can be reduced remarkably and the capacity of the purifying device, if an intermediate heat exchanger is disposed, is also reduced to decrease the plant cost. Further, diffusion of deleterious gases from the primary to the secondary circuits can be prevented as well. (Kamimura, M.)

Detection Test for Leakage of CO2 into Sodium Loop

International Nuclear Information System (INIS)

Park, Sun Hee; Wi, Myung-Hwan; Min, Jae Hong

2015-01-01

This report is about the facility for the detection test for leakage of CO 2 into sodium loop. The facility for the detection test for leakage of CO 2 into sodium loop was introduced. The test will be carried out. Our experimental results are going to be expected to be used for approach methods to detect CO 2 leaking into sodium in heat exchangers. A sodium-and-carbon dioxide (Na-CO 2 ) heat exchanger is one of the key components for the supercritical CO 2 Brayton cycle power conversion system of sodium-cooled fast reactors (SFRs). A printed circuit heat exchanger (PCHE) is considered for the Na-CO 2 heat exchanger, which is known to have potential for reducing the volume occupied by the exchangers compared to traditional shell-and-tube heat exchangers. Among various issues about the Na- CO 2 exchanger, detection of CO 2 leaking into sodium in the heat exchanger is most important thing for its safe operation. It is known that reaction products from sodium and CO 2 such as sodium carbonate (Na 2 CO 3 ) and amorphous carbon are hardly soluble in sodium, which cause plug sodium channels. Detection technique for Na 2 CO 3 in sodium loop has not been developed yet. Therefore, detection of CO 2 and CO from reaction of sodium and CO 2 are proper to detect CO 2 leakage into sodium loop

Electrochemical reduction of disulfide-containing proteins for hydrogen/deuterium exchange monitored by mass spectrometry

DEFF Research Database (Denmark)

Mysling, Simon; Salbo, Rune; Ploug, Michael

2014-01-01

Characterization of disulfide bond-containing proteins by hydrogen/deuterium exchange monitored by mass spectrometry (HDX-MS) requires reduction of the disulfide bonds under acidic and cold conditions, where the amide hydrogen exchange reaction is quenched (pH 2.5, 0 °C). The reduction typically...... of TCEP. In the present study, we explore the feasibility of using electrochemical reduction as a substitute for TCEP in HDX-MS analyses. Our results demonstrate that efficient disulfide bond reduction is readily achieved by implementing an electrochemical cell into the HDX-MS workflow. We also identify...... some challenges in using electrochemical reduction in HDX-MS analyses and provide possible conditions to attenuate these limitations. For example, high salt concentrations hamper disulfide bond reduction, necessitating additional dilution of the sample with aqueous acidic solution at quench conditions....

Mechanism of mercurial inhibition of sodium-coupled alanine uptake in liver plasma membrane vesicles from Raja erinacea

International Nuclear Information System (INIS)

Sellinger, M.; Ballatori, N.; Boyer, J.L.

1991-01-01

In mammalian hepatocytes the L-alanine carrier contains a sulfhydryl group that is essential for its activity and is inhibited by mercurials. In hepatocytes of the evolutionarily primitive little skate (Raja erinacea), HgCl2 inhibits Na(+)-dependent alanine uptake and Na+/K(+)-ATPase and increase K+ permeability. To distinguish between direct effects of HgCl2 on the Na(+)-alanine cotransporter and indirect effects on membrane permeability, [3H]alanine transport was studied in plasma membrane vesicles. [3H]Alanine uptake was stimulated by an out-to-in Na+ but not K+ gradient and was saturable confirming the presence of Na(+)-alanine cotransport in liver plasma membranes from this species. Preincubation of the vesicles with HgCl2 for 5 min reduced initial rates of Na(+)-dependent but not Na(+)-independent alanine uptake in a dose-dependent manner (10-200 microM). In the presence of equal concentrations of NaCl or KCl inside and outside of the vesicles, 75 microM HgCl2 directly inhibited sodium-dependent alanine-[3H]alanine exchange, demonstrating that HgCl2 directly affected the alanine cotransporter. Inhibition of Na(+)-dependent alanine uptake by 30 microM HgCl2 was reversed by dithiothreitol (1 mM). HgCl2 (10-30 microM) also increased initial rates of 22Na uptake (at 5 sec), whereas 22Na uptake rates were decreased at HgCl2 concentrations greater than 50 microM. Higher concentrations of HgCl2 (100-200 microM) produced nonspecific effects on vesicle integrity. These studies indicate that HgCl2 inhibits Na(+)-dependent alanine uptake in skate hepatocytes by three different concentration-dependent mechanisms: direct interaction with the transporters, dissipation of the driving force (Na+ gradient), and loss of membrane integrity

Hydrogen/deuterium exchange, a unique and effective method for MS fragmentation behavior elucidation of ginkgolides and its application to systematic research in Ginkgo biloba.

Science.gov (United States)

Niu, Xingliang; Luo, Jun; Xu, Deran; Zou, Hongyan; Kong, Lingyi

2017-02-05

Ginkgolides, the main active constituents of Ginkgo biloba, possess significant selectively inhibition on platelet-activating factor and pancreatic lipase and attract wide attention in pharmacological research area. In our study, an effective hydrogen/deuterium (H/D) exchange method was developed by exchanging the α-Hs of lactone groups in ginkgolides with Ds, which was very useful for the elucidation of the fragmentation patterns of ginkgolides in Quadrupole Time-of-flight Mass Spectrometry (Q-TOF-MS), especially in accurately distinguishing the type and position of substituent in framework of ginkgolides. Then, a systematic research strategy for qualitative and quantitative analysis of ginkgolides, based on H/D exchange, tandem solid-phase extraction and LC-Q-TOF-MS, was developed, which was successfully applied in each medicinal part of G. biloba, which indicated that ginkgolide B was the most abundant ginkgolide in the seeds of G. biloba (60.6μg/g). This research was the successful application of H/D exchange in natural products, and proved that H/D exchange is a potential method for analysis research of complex TCMs active constituents. Copyright © 2016 Elsevier B.V. All rights reserved.

Measurement and Characterization of Hydrogen-Deuterium Exchange Chemistry Using Relaxation Dispersion NMR Spectroscopy.

Science.gov (United States)

Khirich, Gennady; Holliday, Michael J; Lin, Jasper C; Nandy, Aditya

2018-03-01

One-dimensional heteronuclear relaxation dispersion NMR spectroscopy at 13 C natural abundance successfully characterized the dynamics of the hydrogen-deuterium exchange reaction occurring at the N ε position in l-arginine by monitoring C δ in varying amounts of D 2 O. A small equilibrium isotope effect was observed and quantified, corresponding to ΔG = -0.14 kcal mol -1 . A bimolecular rate constant of k D = 5.1 × 10 9 s -1 M -1 was determined from the pH*-dependence of k ex (where pH* is the direct electrode reading of pH in 10% D 2 O and k ex is the nuclear spin exchange rate constant), consistent with diffusion-controlled kinetics. The measurement of ΔG serves to bridge the millisecond time scale lifetimes of the detectable positively charged arginine species with the nanosecond time scale lifetime of the nonobservable low-populated neutral arginine intermediate species, thus allowing for characterization of the equilibrium lifetimes of the various arginine species in solution as a function of fractional solvent deuterium content. Despite the system being in fast exchange on the chemical shift time scale, the magnitude of the secondary isotope shift due to the exchange reaction at N ε was accurately measured to be 0.12 ppm directly from curve-fitting D 2 O-dependent dispersion data collected at a single static field strength. These results indicate that relaxation dispersion NMR spectroscopy is a robust and general method for studying base-catalyzed hydrogen-deuterium exchange chemistry at equilibrium.

Preservatives and neutralizing substances in milk: analytical sensitivity of official specific and nonspecific tests, microbial inhibition effect, and residue persistence in milk

Directory of Open Access Journals (Sweden)

Livia Cavaletti Corrêa da Silva

2015-09-01

Full Text Available Milk fraud has been a recurring problem in Brazil; thus, it is important to know the effect of most frequently used preservatives and neutralizing substances as well as the detection capability of official tests. The objective of this study was to evaluate the analytical sensitivity of legislation-described tests and nonspecific microbial inhibition tests, and to investigate the effect of such substances on microbial growth inhibition and the persistence of detectable residues after 24/48h of refrigeration. Batches of raw milk, free from any contaminant, were divided into aliquots and mixed with different concentrations of formaldehyde, hydrogen peroxide, sodium hypochlorite, chlorine, chlorinated alkaline detergent, or sodium hydroxide. The analytical sensitivity of the official tests was 0.005%, 0.003%, and 0.013% for formaldehyde, hydrogen peroxide, and hypochlorite, respectively. Chlorine and chlorinated alkaline detergent were not detected by regulatory tests. In the tests for neutralizing substances, sodium hydroxide could not be detected when acidity was accurately neutralized. The yogurt culture test gave results similar to those obtained by official tests for the detection of specific substances. Concentrations of 0.05% of formaldehyde, 0.003% of hydrogen peroxide and 0.013% of sodium hypochlorite significantly reduced (P

Exercise attenuates intermittent hypoxia-induced cardiac fibrosis associated with sodium-hydrogen exchanger-1 in rats

Directory of Open Access Journals (Sweden)

Tsung-I Chen

2016-10-01

Full Text Available Purpose: To investigate the role of sodium–hydrogen exchanger-1 (NHE-1 and exercise training on intermittent hypoxia-induced cardiac fibrosis in obstructive sleep apnea (OSA, using an animal model mimicking the intermittent hypoxia of OSA. Methods: Eight-week-old male Sprague–Dawley rats were randomly assigned to control (CON, intermittent hypoxia (IH, exercise (EXE or IH combined with exercise (IHEXE groups. These groups were randomly assigned to subgroups receiving either a vehicle or the NHE-1 inhibitor cariporide. The EXE and IHEXE rats underwent exercise training on an animal treadmill for 10 weeks (5 days/week, 60 minutes/day, 24–30 m/minute, 2–10% grade. The IH and IHEXE rats were exposed to 14 days of IH (30 seconds of hypoxia - nadir of 2-6% O2 - followed by 45 seconds of normoxia for 8 hours/day. At the end of 10 weeks, rats were sacrificed and then hearts were removed to determine the myocardial levels of fibrosis index, oxidative stress, antioxidant capacity and NHE-1 activation. Results: Compared to the CON rats, IH induced higher cardiac fibrosis, lower myocardial catalase and superoxidative dismutase activities, higher myocardial lipid and protein peroxidation and higher NHE-1 activation (p < 0.05 for each, which were all abolished by cariporide. Compared to the IH rats, lower cardiac fibrosis, higher myocardial antioxidant capacity, lower myocardial lipid and protein peroxidation and lower NHE-1 activation were found in the IHEXE rats (p < 0.05 for each. Conclusion: IH-induced cardiac fibrosis was associated with NHE-1 hyperactivity. However, exercise training and cariporide exerted an inhibitory effect to prevent myocardial NHE-1 hyperactivity, which contributed to reduced IH-induced cardiac fibrosis. Therefore, NHE-1 plays a critical role in the effect of exercise on IH-induced increased cardiac fibrosis.

Human serum paraoxonase-1 (hPON1): in vitro inhibition effects of moxifloxacin hydrochloride, levofloxacin hemihidrate, cefepime hydrochloride, cefotaxime sodium and ceftizoxime sodium.

Science.gov (United States)

Türkeş, Cüneyt; Söyüt, Hakan; Beydemir, Şükrü

2015-01-01

In this study, we investigated the effects of antibacterial drugs (moxifloxacin hydrochloride, levofloxacin hemihidrate, cefepime hydrochloride, cefotaxime sodium and ceftizoxime sodium) on human serum paraoxonase-1 (hPON1) enzyme activity from human serum in vitro conditions. For this purpose, hPON1 enzyme was purified from human serum using simple chromatographic methods. The antibacterial drugs exhibited inhibitory effects on hPON1 at low concentrations. Ki constants were calculated to be 2.641 ± 0.040 mM, 5.525 ± 0.817 mM, 35.092 ± 1.093 mM, 252.762 ± 5.749 mM and 499.244 ± 10.149 mM, respectively. The inhibition mechanism of moxifloxacin hydrochloride was competitive, whereas levofloxacin hemihidrate, cefepime hydrochloride, cefotaxime sodium and ceftizoxime sodium were noncompetitive inhibitors.

Contribution to the study of proteins and peptides structure by hydrogen isotopic exchange

International Nuclear Information System (INIS)

Nabedryk-Viala, Eliane.

1978-01-01

Development of hydrogen exchange measurement methods to study the structure and the molecular interaction of globular protein molecules in aqueous solution (ribonuclease A, cytochrome c, coupling factors of chloroplasts), in peptide hormones in trifluoroethanol solution (angiotensin II, corticotropin) and in proteins of membranes (rhodopsin) [fr

Mapping temperature-induced conformational changes in the Escherichia coli heat shock transcription factor sigma 32 by amide hydrogen exchange

DEFF Research Database (Denmark)

Rist, Wolfgang; Jørgensen, Thomas J D; Roepstorff, Peter

2003-01-01

Stress conditions such as heat shock alter the transcriptional profile in all organisms. In Escherichia coli the heat shock transcription factor, sigma 32, out-competes upon temperature up-shift the housekeeping sigma-factor, sigma 70, for binding to core RNA polymerase and initiates heat shock...... gene transcription. To investigate possible heat-induced conformational changes in sigma 32 we performed amide hydrogen (H/D) exchange experiments under optimal growth and heat shock conditions combined with mass spectrometry. We found a rapid exchange of around 220 of the 294 amide hydrogens at 37...... degrees C, indicating that sigma 32 adopts a highly flexible structure. At 42 degrees C we observed a slow correlated exchange of 30 additional amide hydrogens and localized it to a helix-loop-helix motif within domain sigma 2 that is responsible for the recognition of the -10 region in heat shock...

Experimental study of hydrogen jet ignition and jet extinguishment

International Nuclear Information System (INIS)

Wierman, R.W.

1979-04-01

Two phases are described of an experimental study that investigated: (1) the ignition characteristics of hydrogen--sodium jets, (2) the formation of hydrogen in sodium--humid air atmospheres, and (3) the extinguishment characteristics of burning hydrogen--sodium jets. Test conditions were similar to those postulated for highly-improbable breeder reactor core melt-through accidents and included: jet temperature, jet velocity, jet hydrogen concentration, jet sodium concentration, atmospheric oxygen concentration, and atmospheric water vapor concentration

3.2.1. Synthesis, crystal and molecular structure of catena-(bis(µ1-oxalic acid)-µ3-hydrogen oxalate-di-aqua-sodium(I)).

OpenAIRE

Olga Kovalchukova*, Sergey Aldoshin, Andrey Utenyshev, Konstantin Bogenko, Valeriy Tkachev

2015-01-01

The crystal and molecular structure of catena-(bis(µ- oxalic acid)-µ-hydrogen oxalate-di-aqua-sodium(I)) was detected by X-Ray analysis. The compound crystallizes in the triclinic space group P-1, with a(Å) 6.2378(12); b(Å) 7,1115(14); c(Å) 10.489(2); α(°) 94.65(3); β(°) 100.12(3); γ(°) 97.78(3). The sodium cation in the title compound is eight coordinated and forms a square antiprism. It is surrounded by two molecules of oxalic acid, one hydrogen oxalate anion and one water molecule. Both ox...

Towards quantifying the role of exact exchange in the prediction hydrogen bond spin-spin coupling constants involving fluorine

Energy Technology Data Exchange (ETDEWEB)

San Fabián, J.; Omar, S.; García de la Vega, J. M., E-mail: garcia.delavega@uam.es [Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid (Spain)

2016-08-28

The effect of a fraction of Hartree-Fock exchange on the calculated spin-spin coupling constants involving fluorine through a hydrogen bond is analyzed in detail. Coupling constants calculated using wavefunction methods are revisited in order to get high-level calculations using the same basis set. Accurate MCSCF results are obtained using an additive approach. These constants and their contributions are used as a reference for density functional calculations. Within the density functional theory, the Hartree-Fock exchange functional is split in short- and long-range using a modified version of the Coulomb-attenuating method with the SLYP functional as well as with the original B3LYP. Results support the difficulties for calculating hydrogen bond coupling constants using density functional methods when fluorine nuclei are involved. Coupling constants are very sensitive to the Hartree-Fock exchange and it seems that, contrary to other properties, it is important to include this exchange for short-range interactions. Best functionals are tested in two different groups of complexes: those related with anionic clusters of type [F(HF){sub n}]{sup −} and those formed by difluoroacetylene and either one or two hydrogen fluoride molecules.

Lack of the sodium-driven chloride bicarbonate exchanger NCBE impairs visual function in the mouse retina.

Directory of Open Access Journals (Sweden)

Gerrit Hilgen

Full Text Available Regulation of ion and pH homeostasis is essential for normal neuronal function. The sodium-driven chloride bicarbonate exchanger NCBE (Slc4a10, a member of the SLC4 family of bicarbonate transporters, uses the transmembrane gradient of sodium to drive cellular net uptake of bicarbonate and to extrude chloride, thereby modulating both intracellular pH (pH(i and chloride concentration ([Cl(-](i in neurons. Here we show that NCBE is strongly expressed in the retina. As GABA(A receptors conduct both chloride and bicarbonate, we hypothesized that NCBE may be relevant for GABAergic transmission in the retina. Importantly, we found a differential expression of NCBE in bipolar cells: whereas NCBE was expressed on ON and OFF bipolar cell axon terminals, it only localized to dendrites of OFF bipolar cells. On these compartments, NCBE colocalized with the main neuronal chloride extruder KCC2, which renders GABA hyperpolarizing. NCBE was also expressed in starburst amacrine cells, but was absent from neurons known to depolarize in response to GABA, like horizontal cells. Mice lacking NCBE showed decreased visual acuity and contrast sensitivity in behavioral experiments and smaller b-wave amplitudes and longer latencies in electroretinograms. Ganglion cells from NCBE-deficient mice also showed altered temporal response properties. In summary, our data suggest that NCBE may serve to maintain intracellular chloride and bicarbonate concentration in retinal neurons. Consequently, lack of NCBE in the retina may result in changes in pH(i regulation and chloride-dependent inhibition, leading to altered signal transmission and impaired visual function.

Studies of the hydrous titanium oxide ion exchanger. 4. Rate of the isotopic exchange of sodium ions between the exchanger in the Na+ form and aqueous solution

International Nuclear Information System (INIS)

Inoue, Yasushi; Yamazaki, Hiromichi; Kasuga, Fuminori

1995-01-01

The isotopic exchange rate of Na + between hydrous titanium(IV) oxides, precipitated at pH 6 and 13, in the Na + form and aqueous solution of sodium salt was determined radiochemically. The rate in the exchanger precipitated at pH 6 is controlled by the diffusion of Na + in the exchanger particles (particle diffusion). The diffusion coefficient and its activation energy are 1.9 x 10 -11 m 2 s -1 (pH 12, 5.0degC) and 29 kJ mol -1 (pH 12), respectively. The rate in the exchanger precipitated at pH 13 is also controlled by the particle diffusion. The rate is much slower than that in the other; this can be explained by assuming the existence of two kinds of independently diffusing ions (fast and slow species) in the exchanger. The diffusion coefficients are of the order of 10 -12 and 10 -13 m 2 s -1 for the fast and the slow species, respectively. Their activation energies are 48-60 kJ mol -1 at pH 12. The marked difference in kinetics between two exchanges was interpreted in terms of the difference in the acid-base property and in the microstructure of the matrix. (author)

Electrolyte transport in distal colon of sodium-depleted rats: Effect of sodium repletion

International Nuclear Information System (INIS)

Turnamian, S.G.; Binder, H.J.

1988-01-01

Dietary sodium depletion increases plasma aldosterone level and, as a result, induces amiloride-sensitive electrogenic sodium absorption and electrogenic potassium secretion and stimulates Na + -K + -ATPase activity in rat distal colon, while inhibiting electroneutral sodium chloride absorption. To assess the events that occur as the aldosterone-stimulated colon reverts to normal, unidirectional 22 Na and 36 Cl fluxes were measured under voltage-clamp conditions across isolated distal colonic mucosa of rats that were initially dietary sodium depleted for 7 days and then sodium repleted for varying periods of time before the study. Within 8 h of dietary sodium repletion, plasma aldosterone level and Na + -K + -ATPase activity declined to normal, amiloride-sensitive electrogenic sodium absorption decreased by >90%, and active electrogenic potassium secretion also decreased markedly. In contrast, electroneutral sodium chloride absorption did not completely return to levels seen in normal animals until ∼64-68 h. These results demonstrate that maintenance of electrogenic sodium absorption and potassium secretion are directly dependent on elevated plasma aldosterone levels. The inhibition of electroneutral sodium absorption, although initiated by excess aldosterone, persists after normalization of the plasma aldosterone level, thereby implying that the inhibition is dependent on additional factor(s)

Determination of Equine Cytochrome c Backbone Amide Hydrogen/Deuterium Exchange Rates by Mass Spectrometry Using a Wider Time Window and Isotope Envelope.

Science.gov (United States)

Hamuro, Yoshitomo

2017-03-01

A new strategy to analyze amide hydrogen/deuterium exchange mass spectrometry (HDX-MS) data is proposed, utilizing a wider time window and isotope envelope analysis of each peptide. While most current scientific reports present HDX-MS data as a set of time-dependent deuteration levels of peptides, the ideal HDX-MS data presentation is a complete set of backbone amide hydrogen exchange rates. The ideal data set can provide single amide resolution, coverage of all exchange events, and the open/close ratio of each amide hydrogen in EX2 mechanism. Toward this goal, a typical HDX-MS protocol was modified in two aspects: measurement of a wider time window in HDX-MS experiments and deconvolution of isotope envelope of each peptide. Measurement of a wider time window enabled the observation of deuterium incorporation of most backbone amide hydrogens. Analysis of the isotope envelope instead of centroid value provides the deuterium distribution instead of the sum of deuteration levels in each peptide. A one-step, global-fitting algorithm optimized exchange rate and deuterium retention during the analysis of each amide hydrogen by fitting the deuterated isotope envelopes at all time points of all peptides in a region. Application of this strategy to cytochrome c yielded 97 out of 100 amide hydrogen exchange rates. A set of exchange rates determined by this approach is more appropriate for a patent or regulatory filing of a biopharmaceutical than a set of peptide deuteration levels obtained by a typical protocol. A wider time window of this method also eliminates false negatives in protein-ligand binding site identification. Graphical Abstract ᅟ.

HOGEN{trademark} proton exchange membrane hydrogen generators: Commercialization of PEM electrolyzers

Energy Technology Data Exchange (ETDEWEB)

Smith, W.F.; Molter, T.M. [Proton Energy Systems, Inc., Rocky Hill, CT (United States)

1997-12-31

PROTON Energy Systems` new HOGEN series hydrogen generators are Proton Exchange Membrane (PEM) based water electrolyzers designed to generate 300 to 1000 Standard Cubic Feet Per Hour (SCFH) of high purity hydrogen at pressures up to 400 psi without the use of mechanical compressors. This paper will describe technology evolution leading to the HOGEN, identify system design performance parameters and describe the physical packaging and interfaces of HOGEN systems. PEM electrolyzers have served US and UK Navy and NASA needs for many years in a variety of diverse programs including oxygen generators for life support applications. In the late 1970`s these systems were advocated for bulk hydrogen generation through a series of DOE sponsored program activities. During the military buildup of the 1980`s commercial deployment of PEM hydrogen generators was de-emphasized as priority was given to new Navy and NASA PEM electrolysis systems. PROTON Energy Systems was founded in 1996 with the primary corporate mission of commercializing PEM hydrogen generators. These systems are specifically designed and priced to meet the needs of commercial markets and produced through manufacturing processes tailored to these applications. The HOGEN series generators are the first step along the path to full commercial deployment of PEM electrolyzer products for both industrial and consumer uses. The 300/1000 series are sized to meet the needs of the industrial gases market today and provide a design base that can transition to serve the needs of a decentralized hydrogen infrastructure tomorrow.

Relationship Between Equilibrium Hydrogen Pressure and Exchange Current for the Hydrogen Electrode-Reaction at Mmni(3.9-X)Mn(0.4)A1(X)Co(0.7) Alloy Electrodes

NARCIS (Netherlands)

Senoh, H.; Morimoto, K.; Inoue, H.; Iwakura, C.; Notten, P.H.L.

2000-01-01

We present a theoretical relationship between equilibrium hydrogen pressure and exchange current for the hydrogen electrode reaction which considers the degree of hydrogen coverage at the electrode surface. Electrochemical measurements at MmNi3.9–xMn0.4AlxCo0.7 (0 x 0.8) electrodes were performed to

Sodium removal disassembly and examination of the Fermi secondary sodium pump

International Nuclear Information System (INIS)

Maffei, H.P.; Funk, C.W.; Ballif, J.L.

1974-01-01

The Fermi secondary pump is a centrifugal single stage design. The pump had been operated more than 42,000 hours between 450 and 800 0 F. Sodium was drained from the pump in 1973 and the system was back filled with carbon dioxide. The pump was fabricated for 2.25 Cr-1 Mo Croloy steel. Prior to cleaning the pump was inerted and heated with 150 0 F nitrogen using the pump casing as the containment vessel. The water-vapor-nitrogen process was used in three increasing stages of water concentration. The hydrogen concentration in the discharge line was followed as an indicator of the sodium-water reaction rate. Upon completion of the hydrogen evolution, the pump was rinsed several times with hot water. Six pounds of sodium were removed from the pump during a process cycle of 79 hours including rinsing. The maximum pump temperature recorded was 175 0 F with no variation exceeding 10 0 F. The hydrogen concentration in the effluent provided a very satisfactory index for control of the reaction by adjustment of the water-vapor concentration feed to the system. Rinsing effectiveness was limited by a pool of water in the volute that was not drainable with the available system hook up. Sodium and its compounds were removed from all internal surfaces that could be observed by the first stage of disassembly. All such surfaces were coated with a black deposit. Areas above the sodium liquid level were coated with a vermillion colored oxide. Sodium was found on the (1) threads of the impeller nut lock screw, (2) impeller nut-tapered shaft interface, and (3) vapor deposited sodium was found in the oil seal

The influence of sodium chlorides fog on corrosion resistance of heat exchangers used in automotive

Directory of Open Access Journals (Sweden)

Peta Katarzyna

2017-01-01

Full Text Available In the work, the most important factors which influence on the exploitative durability of heat exchangers are classified. Particular attention was paid to the compounds of sodium chloride used in the winter season for road maintenance. In order to determine their impact on automotive heat exchanger corrosion resistance, a test of heaters in a salt chamber which imitates the conditions of their work was realized. It also allows to verify the durability of these products. To evaluate the corrosion changes, observation with the use of light microscopy and scanning microscopy SEM were made supplemented with microanalysis of chemical composition by EDS spectroscopy method. Critical areas in the heat exchangers which are mostly exposed to damage including the formation of local corrosion pits were located and analyzed.

pH-Dependent isotope exchange and hydrogenation catalysed by water-soluble NiRu complexes as functional models for [NiFe]hydrogenases.

Science.gov (United States)

Kure, Bunsho; Matsumoto, Takahiro; Ichikawa, Koji; Fukuzumi, Shunichi; Higuchi, Yoshiki; Yagi, Tatsuhiko; Ogo, Seiji

2008-09-21

The pH-dependent hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes and hydrogenation of the carbonyl compounds have been investigated with water-soluble bis(mu-thiolate)(mu-hydride)NiRu complexes, Ni(II)(mu-SR)(2)(mu-H)Ru(II) {(mu-SR)(2) = N,N'-dimethyl-N,N'-bis(2-mercaptoethyl)-1,3-propanediamine}, as functional models for [NiFe]hydrogenases. In acidic media (at pH 4-6), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes has H(+) properties, and the complexes catalyse the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes. A mechanism of the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes through a low-valent Ni(I)(mu-SR)(2)Ru(I) complex is proposed. In contrast, in neutral-basic media (at pH 7-10), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes acts as H(-), and the complexes catalyse the hydrogenation of carbonyl compounds.

Expression of the Sodium/Calcium/Potassium Exchanger, NCKX4, in Ameloblasts

Science.gov (United States)

Hu, Ping; Lacruz, Rodrigo S.; Smith, Charles E.; Smith, Susan M.; Kurtz, Ira; Paine, Michael L.

2012-01-01

Transcellular calcium transport is an essential activity in mineralized tissue formation, including dental hard tissues. In many organ systems, this activity is regulated by membrane-bound sodium/calcium (Na+/Ca2+) exchangers, which include the NCX and NCKX [sodium/calcium-potassium (Na+/Ca2+-K+ ) exchanger] proteins. During enamel maturation, when crystals expand in thickness, Ca2+ requirements vastly increase but exactly how Ca2+ traffics through ameloblasts remains uncertain. Previous studies have shown that several NCX proteins are expressed in ameloblasts, although no significant shifts in expression were observed during maturation which pointed to the possible identification of other Ca2+ membrane transporters. NCKX proteins are encoded by members of the solute carrier gene family, Slc24a, which include 6 different proteins (NCKX1–6). NCKX are bidirectional electrogenic transporters regulating Ca2+ transport in and out of cells dependent on the transmembrane ion gradient. In this study we show that all NCKX mRNAs are expressed in dental tissues. Real-time PCR indicates that of all the members of the NCKX group, NCKX4 is the most highly expressed gene transcript during the late stages of amelogenesis. In situ hybridization and immunolocalization analyses clearly establish that in the enamel organ, NCKX4 is expressed primarily by ameloblasts during the maturation stage. Further, during the mid-late maturation stages of amelogenesis, the expression of NCKX4 in ameloblasts is most prominent at the apical poles and at the lateral membranes proximal to the apical ends. These data suggest that NCKX4 might be an important regulator of Ca2+ transport during amelogenesis. PMID:22677781

Transformation of sodium from the Rapsodie fast breeder reactor into sodium hydroxide

International Nuclear Information System (INIS)

Roger, J.; Latge, C.; Rodriguez, G.

1994-01-01

One of the major problems raised by decommissioning a fast breeder reactor (FBR) concerns the disposal of the sodium coolant. The Desora operation was undertaken to eliminate the Rapsodie primary sodium as part of the partial decommissioning program, and to develop an operational sodium treatment unit for other needs. The process involves reacting small quantities of sodium in water inside a closed vessel, producing aqueous sodium hydroxide and hydrogen gas. It is described in this work. (O.L.). 4 figs

OPTIMIZATION OF INTERNAL HEAT EXCHANGERS FOR HYDROGEN STORAGE TANKS UTILIZING METAL HYDRIDES

Energy Technology Data Exchange (ETDEWEB)

Garrison, S.; Tamburello, D.; Hardy, B.; Anton, D.; Gorbounov, M.; Cognale, C.; van Hassel, B.; Mosher, D.

2011-07-14

Two detailed, unit-cell models, a transverse fin design and a longitudinal fin design, of a combined hydride bed and heat exchanger are developed in COMSOL{reg_sign} Multiphysics incorporating and accounting for heat transfer and reaction kinetic limitations. MatLab{reg_sign} scripts for autonomous model generation are developed and incorporated into (1) a grid-based and (2) a systematic optimization routine based on the Nelder-Mead downhill simplex method to determine the geometrical parameters that lead to the optimal structure for each fin design that maximizes the hydrogen stored within the hydride. The optimal designs for both the transverse and longitudinal fin designs point toward closely-spaced, small cooling fluid tubes. Under the hydrogen feed conditions studied (50 bar), a 25 times improvement or better in the hydrogen storage kinetics will be required to simultaneously meet the Department of Energy technical targets for gravimetric capacity and fill time. These models and methodology can be rapidly applied to other hydrogen storage materials, such as other metal hydrides or to cryoadsorbents, in future work.

Measurement of backbone hydrogen-deuterium exchange in the type III secretion system needle protein PrgI by solid-state NMR

Science.gov (United States)

Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

2017-10-01

In this report we present site-specific measurements of amide hydrogen-deuterium exchange rates in a protein in the solid state phase by MAS NMR. Employing perdeuteration, proton detection and a high external magnetic field we could adopt the highly efficient Relax-EXSY protocol previously developed for liquid state NMR. According to this method, we measured the contribution of hydrogen exchange on apparent 15N longitudinal relaxation rates in samples with differing D2O buffer content. Differences in the apparent T1 times allowed us to derive exchange rates for multiple residues in the type III secretion system needle protein.

Poly(neutral red) based hydrogen peroxide biosensor for chromium determination by inhibition measurements.

Science.gov (United States)

Attar, Aisha; Emilia Ghica, M; Amine, Aziz; Brett, Christopher M A

2014-08-30

Amperometric hydrogen peroxide enzyme inhibition biosensors based on horseradish peroxidase (HRP) immobilised on electropolymerised neutral red (NR) or directly on the surface of carbon film electrodes (CFE) have been successfully applied to the determination of toxic Cr(III) and Cr(VI). Parameters influencing the performance of the biosensor including the enzyme immobilisation method, the amount of hydrogen peroxide, applied potential and electrolyte pH were optimised. The inhibition of horseradish peroxidase by the chromium species was studied under the optimised conditions. Results from the quantitative analysis of chromium ions are discussed in terms of detection limit, linear range and sensitivity. The HRP kinetic interactions reveal mixed binding of Cr(III) with I50=3.8μM and inhibition binding constant Ki=11.3μM at HRP/PNR/CFE biosensors and uncompetitive binding of Cr(VI) with I50=3.9μM and Ki=0.78μM at HRP/CFE biosensors in the presence of H2O2 substrate. Interferences from other heavy metal ions were studied and the inhibition show very good selectivity towards Cr(III) and Cr(VI). Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of sodium dodecyl sulfate on the reaction between Nile Blue A and hydrogen peroxide

Directory of Open Access Journals (Sweden)

IVANA A. JANKOVIC

1999-05-01

Full Text Available The influence of the anionic surfactant sodium dodecyl sulfate on the rate of the reaction between the cationic form of Nile Blue A and hydrogen peroxide was investigated in the pH range from 5 to 8.5. A retardation of the oxidation of Nile Blue A with hydrogen peroxide of three orders of magnitude was observed at pH 8.5 in the presence of anionic micelles compared to the kinetic data in water. The retardation effect was less pronounced at lower pH values. These effects were explained by the electrostatic interaction of the species involved in the reaction with the negatively charged micellar surface and their effective separation in the vicinity of the micellar surface.

Zinc oxide and chromia as catalysts for the isomerization of butene, the hydrogenation of ethylene, and the isotopic exchange and allotropic conversion of hydrogen

International Nuclear Information System (INIS)

Conner, W.C. Jr.

1973-01-01

Hydrogenation of olefins has been studied over metals and metal oxides. Over metals the following observations generalize the characteristics of hydrogenation and isomerization. Metal hydrogenation catalysts are effective for H 2 -D 2 exchange (and para hydrogen conversion) under the same conditions as they effect olefin hydrogenation. This suggests that hydrogen ''activation'' involves formation of hydrogen atoms as a surface intermediate. Addition of deuterium to light ethylene leads to ethane products of the form C 2 H/sub 6-x/D/sub x/ (where 0 less than or equal to x less than or equal to 6). This is a result of the reversal of the alkyl (C 2 H 5 *) formation on the surface. Moreover, efficient isomerization of olefins require hydrogen as a co-catalyst. Both these observations suggest that alkyl formation and its reversal play a major role in hydrogenation and related reactions over metals. In this work it is found that zinc oxide catalyzes the deuteration of ethylene to dideuterioethane selectivity. Furthermore, the hydrogenation of ethylene using mixtures of hydrogen and deuterium indicate that hydrogenation occurs in such a manner as to reflect the molecular identity of the gas phase in the product ethane

Detection Test for Leakage of CO{sub 2} into Sodium Loop

Energy Technology Data Exchange (ETDEWEB)

Park, Sun Hee; Wi, Myung-Hwan; Min, Jae Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

This report is about the facility for the detection test for leakage of CO{sub 2} into sodium loop. The facility for the detection test for leakage of CO{sub 2} into sodium loop was introduced. The test will be carried out. Our experimental results are going to be expected to be used for approach methods to detect CO{sub 2} leaking into sodium in heat exchangers. A sodium-and-carbon dioxide (Na-CO{sub 2}) heat exchanger is one of the key components for the supercritical CO{sub 2} Brayton cycle power conversion system of sodium-cooled fast reactors (SFRs). A printed circuit heat exchanger (PCHE) is considered for the Na-CO{sub 2} heat exchanger, which is known to have potential for reducing the volume occupied by the exchangers compared to traditional shell-and-tube heat exchangers. Among various issues about the Na- CO{sub 2} exchanger, detection of CO{sub 2} leaking into sodium in the heat exchanger is most important thing for its safe operation. It is known that reaction products from sodium and CO{sub 2} such as sodium carbonate (Na{sub 2}CO{sub 3}) and amorphous carbon are hardly soluble in sodium, which cause plug sodium channels. Detection technique for Na{sub 2}CO{sub 3} in sodium loop has not been developed yet. Therefore, detection of CO{sub 2} and CO from reaction of sodium and CO{sub 2} are proper to detect CO{sub 2} leakage into sodium loop.

Reaction of Hydrogen Chloride Gas with Sodium Carbonate and Its Deep Removal in a Fixed-Bed Reactor

Czech Academy of Sciences Publication Activity Database

Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Šyc, Michal; Chen, Po-Ch.

2014-01-01

Roč. 53, č. 49 (2014), s. 19145-19158 ISSN 0888-5885 R&D Projects: GA ČR GC14-09692J Grant - others:NSC(TW) 102WBS0300011 Institutional support: RVO:67985858 Keywords : hot fuel gas purification * hydrogen chloride gas * active sodium carbonate Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.587, year: 2014

Preliminary design analysis of hot gas ducts and a intermediate heat exchanger for the nuclear hydrogen reactor

International Nuclear Information System (INIS)

Song, K. N.; Kim, Y. W.

2008-01-01

Korea Atomic Energy Research Institute (KAERI) is in the process of carrying out a nuclear hydrogen system by considering the indirect cycle gas cooled reactors that produce heat at temperatures in the order of 950 .deg. C. Primary and secondary hot gas ducts with coaxial double tubes and are key components connecting a reactor pressure vessel and a intermediate heat exchanger for the nuclear hydrogen system. In this study, preliminary design analyses on the hot gas ducts and the intermediate heat exchanger were carried out. These preliminary design activities include a preliminary design on the geometric dimensions, a preliminary strength evaluation, thermal sizing, and an appropriate material selection

Adsorption separation factors for hydrogen--deuterium (H/sub 2/-HD-D/sub 2/) mixtures on synthetic mordenite at 48 to 62/sup 0/K. [Reaction Kinetics

Energy Technology Data Exchange (ETDEWEB)

Parbuzin, V S; Kuryakov, Yu N

1975-07-01

The temperature dependence of selectivity has been determined for the adsorption of hydrogen isotopes by sodium mordenite. Heats and entropies of exchange of the isotopic molecules in the gas-zeolite system have been calculated from the experimental results. (auth)

Ni-polymer nanogel hybrid particles: A new strategy for hydrogen production from the hydrolysis of dimethylamine-borane and sodium borohydride

International Nuclear Information System (INIS)

Cai, Haokun; Liu, Liping; Chen, Qiang; Lu, Ping; Dong, Jian

2016-01-01

Efficient non-precious metal catalysts are crucial for hydrogen production from borohydride compounds in aqueous media via hydrogen atoms in water. A method for preparing magnetic polymer nanoparticles is developed in this study based on the chemical deposition of nickel onto hydrophilic polymer nanogels. High-resolution transmission electron microscopic and XPS analyses show that Ni exists mainly in the form of NiO in nanogels. Excellent catalytic activities of the nanoparticles are demonstrated for hydrogen generation from the hydrolysis of dimethylamine-borane and sodium borohydride in which the initial TOF (turn-over frequencies) are 376 and 1919 h"−"1, respectively. Kinetic studies also reveal an Arrhenius activation energy of 50.96 kJ mol"−"1 for the hydrolysis of dimethylamine-borane and 47.82 kJ mol"−"1 for the hydrolysis of sodium borohydride, which are lower than those catalyzed by Ru metal. Excellent reusability and the use of water for hydrogen production from dimethylamine-borane provide the additional benefit of using a hybrid catalyst. The principle illustrated in the present study offers a new strategy to explore polymer-transition metal hybrid particles for hydrogen energy technology. - Highlights: • Electroless Ni plating on polymer nanogels generated recyclable catalysts. • The Ni particles proved efficient for H_2 production from borohydride compounds. • The catalysts have lower activation energies than Ru for the hydrolysis. • Borohydride hydrolysis is more beneficial than dehydrogenation in organic solvent.

Charge-exchange neutral hydrogen measurements in TFTR using Pd-MOS microsensors

International Nuclear Information System (INIS)

Bastasz, R.; Kilpatrick, S.J.; Ruzic, D.N.

1991-06-01

An array of Pd-metal-oxide semiconductor (Pd-MOS) diodes has been used to monitor the fluence and energy of charge-exchange neutral hydrogen isotopes striking the wall of the Tokamak Fusion Test Reactor (TFTR). The array was positioned 4 cm behind the graphite-tiled wall at the toroidal midplane and exposed to several hundred plasma discharges. Hydrogen isotopes striking the Pd-MOS diodes were detected by measuring the leakage current, which is affected by the presence of these species at the Pd/SiO 2 interface. It was found that the midplane flux strongly increased for neutral-beam heated plasmas and correlated with co-injected neutral beam power. The majority of the neutral flux was <50 eV in energy but its energy distribution extended to above 500 eV. 20 refs., 4 figs

Hg/HgO electrode and hydrogen evolution potentials in aqueous sodium hydroxide

Energy Technology Data Exchange (ETDEWEB)

Nickell, Ryan A.; Zhu, Wenhua H.; Payne, Robert U.; Cahela, Donald R.; Tatarchuk, Bruce J. [Center for Microfibrous Materials Manufacturing, Department of Chemical Engineering, 230 Ross Hall, Auburn University, Auburn, AL 36849 (United States)

2006-10-27

The Hg/HgO electrode is usually utilized as a reference electrode in alkaline solution such as for development of an alkaline hydrogen electrode. The reference electrode provides a suitable reference point but is available from few commercial vendors and suffers from inadequate documentation on potential in varying electrolytes. A new numerical method uses activity, activity coefficients, and a few correlated empirical equations to determine the potential values in both dilute and concentrated sodium hydroxide solutions at temperatures of 0-90{sup o}C and at concentrations of 0.100-12.8mol kg{sub H{sub 2}O}{sup -1}. The computed potentials of the Hg/HgO electrodes versus a normal hydrogen electrode (NHE) at 25{sup o}C and 1atm are 0.1634V for 0.100m, 0.1077V for 1.00m, and 0.0976V for 1.45m NaOH solutions. The Hg/HgO reduction potential further changes to -0.0751V versus NHE and hydrogen evolution potential changes to -0.9916V versus NHE in a solution of 30.0wt.% NaOH at 80{sup o}C. The calculated values are compared with the measured data at 25 and 75{sup o}C. The experimental data agree well with the numerical values computed from the theoretical and empirical equations. (author)

Hydrogen sulfide prolongs postharvest storage of fresh-cut pears (Pyrus pyrifolia by alleviation of oxidative damage and inhibition of fungal growth.

Directory of Open Access Journals (Sweden)

Kang-Di Hu

Full Text Available Hydrogen sulfide (H2S has proved to be a multifunctional signaling molecule in plants and animals. Here, we investigated the role of H2S in the decay of fresh-cut pears (Pyrus pyrifolia. H2S gas released by sodium hydrosulfide (NaHS prolonged the shelf life of fresh-cut pear slices in a dose-dependent manner. Moreover, H2S maintained higher levels of reducing sugar and soluble protein in pear slices. H2S significantly reduced the accumulation of hydrogen peroxide (H2O2, superoxide radicals (•O2(- and malondialdehyde (MDA. Further investigation showed that H2S fumigation up-regulated the activities of antioxidant enzymes ascorbate peroxidase (APX, catalase (CAT, and guaiacol peroxidase (POD, while it down-regulated those of lipoxygenase (LOX, phenylalanine ammonia lyase (PAL and polyphenol oxidase (PPO. Furthermore, H2S fumigation effectively inhibited the growth of two fungal pathogens of pear, Aspergillus niger and Penicillium expansum, suggesting that H2S can be developed as an effective fungicide for postharvest storage. The present study implies that H2S is involved in prolonging postharvest storage of pears by acting as an antioxidant and fungicide.

Minor Actinide Separations Using Ion Exchangers Or Ionic Liquids

International Nuclear Information System (INIS)

Hobbs, D.; Visser, A.; Bridges, N.

2011-01-01

This project seeks to determine if (1) inorganic-based ion exchange materials or (2) electrochemical methods in ionic liquids can be exploited to provide effective Am and Cm separations. Specifically, we seek to understand the fundamental structural and chemical factors responsible for the selectivity of inorganic-based ion-exchange materials for actinide and lanthanide ions. Furthermore, we seek to determine whether ionic liquids can serve as the electrolyte that would enable formation of higher oxidation states of Am and other actinides. Experiments indicated that pH, presence of complexants and Am oxidation state exhibit significant influence on the uptake of actinides and lanthanides by layered sodium titanate and hybrid zirconium and tin phosphonate ion exchangers. The affinity of the ion exchangers increased with increasing pH. Greater selectivity among Ln(III) ions with sodium titanate materials occurs at a pH close to the isoelectric potential of the ion exchanger. The addition of DTPA decreased uptake of Am and Ln, whereas the addition of TPEN generally increases uptake of Am and Ln ions by sodium titanate. Testing confirmed two different methods for producing Am(IV) by oxidation of Am(III) in ionic liquids (ILs). Experimental results suggest that the unique coordination environment of ionic liquids inhibits the direct electrochemical oxidation of Am(III). The non-coordinating environment increases the oxidation potential to a higher value, while making it difficult to remove the inner coordination of water. Both confirmed cases of Am(IV) were from the in-situ formation of strong chemical oxidizers.

Measuring the hydrogen/deuterium exchange of proteins at high spatial resolution by mass spectrometry: overcoming gas-phase hydrogen/deuterium scrambling.

Science.gov (United States)

Rand, Kasper D; Zehl, Martin; Jørgensen, Thomas J D

2014-10-21

Proteins are dynamic molecules that exhibit conformational flexibility to function properly. Well-known examples of this are allosteric regulation of protein activity and ligand-induced conformational changes in protein receptors. Detailed knowledge of the conformational properties of proteins is therefore pertinent to both basic and applied research, including drug development, since the majority of drugs target protein receptors and a growing number of drugs introduced to the market are therapeutic peptides or proteins. X-ray crystallography provides a static picture at atomic resolution of the lowest-energy structure of the native ensemble. There is a growing need for sensitive analytical tools to explore all of the significant molecular structures in the conformational landscape of proteins. Hydrogen/deuterium exchange monitored by mass spectrometry (HDX-MS) has recently emerged as a powerful method for characterizing protein conformational dynamics. The basis of this method is the fact that backbone amides in stable hydrogen-bonded structures (e.g., α-helices and β-sheets) are protected against exchange with the aqueous solvent. All protein structures are dynamic, however, and eventually all of the protecting hydrogen bonds will transiently break as the protein--according to thermodynamic principles--cycles through partially unfolded states that correspond to excited free energy levels. As a result, all of the backbone amides will eventually become temporarily solvent-exposed and exchange-competent over time. Consequently, a folded protein in D2O will gradually incorporate deuterium into its backbone amides, and the kinetics of the process can be readily monitored by mass spectrometry. The deuterium uptake kinetics for the intact protein (global exchange kinetics) represents the sum of the exchange kinetics for the individual backbone amides. Local exchange kinetics is typically achieved by using pepsin digestion under quench conditions (i.e., under cold

Dispersion- and Exchange-Corrected Density Functional Theory for Sodium Ion Hydration.

Science.gov (United States)

Soniat, Marielle; Rogers, David M; Rempe, Susan B

2015-07-14

A challenge in density functional theory is developing functionals that simultaneously describe intermolecular electron correlation and electron delocalization. Recent exchange-correlation functionals address those two issues by adding corrections important at long ranges: an atom-centered pairwise dispersion term to account for correlation and a modified long-range component of the electron exchange term to correct for delocalization. Here we investigate how those corrections influence the accuracy of binding free energy predictions for sodium-water clusters. We find that the dual-corrected ωB97X-D functional gives cluster binding energies closest to high-level ab initio methods (CCSD(T)). Binding energy decomposition shows that the ωB97X-D functional predicts the smallest ion-water (pairwise) interaction energy and larger multibody contributions for a four-water cluster than most other functionals - a trend consistent with CCSD(T) results. Also, ωB97X-D produces the smallest amounts of charge transfer and the least polarizable waters of the density functionals studied, which mimics the lower polarizability of CCSD. When compared with experimental binding free energies, however, the exchange-corrected CAM-B3LYP functional performs best (error <1 kcal/mol), possibly because of its parametrization to experimental formation enthalpies. For clusters containing more than four waters, "split-shell" coordination must be considered to obtain accurate free energies in comparison with experiment.

Computer analysis of sodium cold trap design and performance

International Nuclear Information System (INIS)

McPheeters, C.C.; Raue, D.J.

1983-11-01

Normal steam-side corrosion of steam-generator tubes in Liquid Metal Fast Breeder Reactors (LMFBRs) results in liberation of hydrogen, and most of this hydrogen diffuses through the tubes into the heat-transfer sodium and must be removed by the purification system. Cold traps are normally used to purify sodium, and they operate by cooling the sodium to temperatures near the melting point, where soluble impurities including hydrogen and oxygen precipitate as NaH and Na 2 O, respectively. A computer model was developed to simulate the processes that occur in sodium cold traps. The Model for Analyzing Sodium Cold Traps (MASCOT) simulates any desired configuration of mesh arrangements and dimensions and calculates pressure drops and flow distributions, temperature profiles, impurity concentration profiles, and impurity mass distributions

Steam generators of Phenix: Measurement of the hydrogen concentration in sodium for detecting water leaks in the steam generator tubes; Generateurs de vapeur de Phenix-mesure de la concentration d'hydrogene du sodium pour la surveillance de l'etancheite des tubes d'eau-vapeur

Energy Technology Data Exchange (ETDEWEB)

Cambillard, E; Lacroix, A; Langlois, J; Viala, J

1975-07-01

The Phenix secondary circuits are provided with measurement systems of hydrogen concentration in sodium, that allow for the detection of possible water leaks in steam generators and the location of a faulty module. A measurement device consists of : a detector with nickel membranes of 0, 3 mm wall thickness, an ion pump with a 200 l/s flow rate, a quadrupole mass spectrometer and a calibrated hydrogen leak. The temperature correction is made automatically. The main tests carried out on the leak detection systems are reported. Since the first system operation (October 24, 1973), the measurements allowed us to obtain the hydrogen diffusion rates through the steam generator tube walls. (author)

Kinetics and mechanism of the furan peroxide formation in the reaction of furfural with hydrogen peroxide in the presence and absence of sodium molybdate

International Nuclear Information System (INIS)

Grunskaya, E.P.; Badovskaya, L.A.; Kaklyugina, T.Ya.; Poskonin, V.V.

2000-01-01

Kinetics of the initial stage of the reaction of furfural with hydrogen peroxide are studied in the presence of Na 2 MoO 4 in water and without catalytic additions in n-butanol. Organic peroxide having in its disposal Mo(6), which is the only product on the initial stage of the reaction, is formed since the first minutes of oxidation of furfural by hydrogen peroxide with the presence of Na 2 MoO 4 . The mechanisms of conversion of furfural in the Na 2 MoO 4 - H 2 O system and its oxidation by peroxide without sodium molybdate are discussed. Schemes of formation of furfural complexes based on the results of kinetic studies are suggested. Comparison of obtained data demonstrates that presence of the sodium molybdates in the reaction medium trends to change of reaction procedure in the hydrogen peroxide [ru

Deuterium exchange between hydrogen and water in a trickle bed reactor

International Nuclear Information System (INIS)

Enright, J.T.; Chuang, T.T.

1978-01-01

The catalyzed exchange of deuterium between hydrogen and liquid water has been studied as the basis for a heavy water production process. Platinum catalyst which had been waterproofed with Teflon was tested in a 0.2 m diameter trickle bed reactor at pressures and temperatures up to 6 MPa and 440 K. Extensive experimental data were used to test a model of the system which was developed from fundamental principles. It was found that mass transfer plays a very important role in the overall exchange and the conventional theory of vapour/liquid mass transfer does not adequately describe the absorption process. Modelling of the data has resulted in the postulation of a second method of mass transfer whereby HDO transfers directly from the catalyst to the bulk liquid phase. (author)

Hydrogen exchange kinetics in a membrane protein determined by 15N NMR spectroscopy: Use of the INEPT [insensitive nucleus enhancement by polarization transfer] experiment to follow individual amides in detergent-solubilized M13 coat protein

International Nuclear Information System (INIS)

Henry, G.D.; Sykes, B.D.

1990-01-01

The coat protein of the filamentous coliphage M13 is a 50-residue polypeptide which spans the inner membrane of the Escherichia coli host upon infection. Amide hydrogen exchange kinetics have been used to probe the structure and dynamics of M13 coat protein which has been solubilized in sodium dodecyl sulfate (SDS) micelles. In a previous 1 H nuclear magnetic resonance (NMR) study, multiple exponential analysis of the unresolved amide proton envelope revealed the existence of two slow kinetic sets containing a total of about 30 protons. The slower set (15-20 amides) originates from the hydrophobic membrane-spanning region and exchanges at least 10 5 -fold slower than the unstructured, non-H-bonded model polypeptide poly(DL-alanine). Herein the authors use 15 N NMR spectroscopy of biosynthetically labeled coat protein to follow individual, assigned, slowly exchanging amides in or near the hydrophobic segment. The INEPT (insensitive nucleus enhancement by polarization transfer) experiments can be used to transfer magnetization to the 15 N nucleus from a coupled proton; when 15 N-labeled protonated protein is dissolved in 2 H 2 O, the INEPT signal disappears with time as the amide protons are replaced by solvent deuterons. Amide hydrogen exchange is catalyzed by both H + and OH - ions. The time-dependent exchange-out experiment is suitable for slow exchange rates (k ex ). The INEPT experiment was also adapted to measure some of the more rapidly exchanging amides in the coat protein using either saturation transfer from water or exchange effects on the polarization transfer step itself. The results of all of these experiments are consistent with previous models of the coat protein in which a stable segment extends from the hydrophobic membrane-spanning region through to the C-terminus, whereas the N-terminal region is undergoing more extensive dynamic fluctuations

The relationship between Na+/H+ exchanger expression and tyrosinase activity in human melanocytes

International Nuclear Information System (INIS)

Smith, Dustin R.; Spaulding, Deborah T.; Glenn, Hayden M.; Fuller, Bryan B.

2004-01-01

The activity of melanosome-associated tyrosinase in human melanocytes differs based on racial skin type. In melanocytes from Black skin, tyrosinase activity is high while in White melanocytes the activity of the enzyme is low. Recent studies suggest that low tyrosinase activity in White melanocytes may be due to an acidic pH environment within the melanosome. Because sodium/hydrogen (Na + /H + ) exchangers (NHEs) are known to regulate intracellular pH, melanocytes were treated with NHE inhibitors to determine what effect this inhibition might have on tyrosinase activity. Treatment of Black melanocytes with ethyl-isopropyl amiloride (EIPA) caused a rapid dose-dependent inhibition of tyrosinase activity. This inhibition was not due to either direct enzyme inhibition or to a decrease in tyrosinase abundance. In contrast, treatment of White melanocytes with EIPA, cimetidine, or clonidine resulted in little inhibition of tyrosinase activity. Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis showed that both Black and White melanocytes expressed mRNA and protein for NHE-1, NHE-3, NHE-5, NHE-6, and NHE-7. Immunohistochemical analysis showed that NHE-7 and NHE-3 co-localized with the melanosomal protein, Tyrosinase Related Protein-1 (TRP-1). In addition, the vesicular proton pump, vesicular ATPase (V-ATPase), was found to be present in both White and Black melanosomes, indicating that organelles from both racial skin types are capable of being acidified. The results suggest that one or more NHEs may help regulate melanosome pH and tyrosinase activity in human melanocytes

An NMR-based quenched hydrogen exchange investigation of model amyloid fibrils formed by cold shock protein A.

Science.gov (United States)

Alexandrescu, A T

2001-01-01

Acid-denatured cold shock protein A (CspA) self-assembles into polymers with properties typical of amyloid fibrils. In the present work, a quenched hydrogen exchange experiment was used to probe the interactions of CspA fibrils with solvent. Exchange was initiated by incubating suspensions of fibrils in D2O, and quenched by flash freezing. Following lyophilization, exchange-quenched samples were dissolved in 90% DMSO/10% D2O, giving DMSO-denatured monomers. Intrinsic exchange rates for denatured CspA in 90% DMSO/10% D2O (pH* 4.5) were sufficiently slow (approximately 1 x 10(-3) min-1) to enable quantification of NMR signal intensity decays due to H/D exchange in the fibrils. Hydrogen exchange rate constants for CspA fibrils were found to vary less than 3-fold from a mean value of 5 x 10(-5) min-1. The uniformity of rate constants suggests that exchange is in the EX1 limit, and that the mechanism of exchange involves a cooperative dissociation of CspA monomers from fibrils, concomitant with unfolding. Previous studies indicated that the highest protection factors in native CspA are approximately 10(3), and that protection factors for the acid-denatured monomer precursors of CspA fibrils are close to unity. Because exchange in is in the EX1 regime, it is only possible to place a lower limit of at least 10(5) on protection factors in CspA fibrils. The observation that all amide protons are protected from exchange indicates that the entire CspA polypeptide chain is structured in the fibrils.

NCBI nr-aa BLAST: CBRC-CBRI-05-0338 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-CBRI-05-0338 ref|YP_001274788.1| sodium/hydrogen exchanger [Roseiflexus sp. RS...-1] gb|ABQ88838.1| sodium/hydrogen exchanger [Roseiflexus sp. RS-1] YP_001274788.1 0.62 25% ...

NCBI nr-aa BLAST: CBRC-DYAK-02-0055 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-DYAK-02-0055 ref|ZP_01751418.1| sodium/hydrogen exchanger [Roseobacter sp. CCS...2] gb|EBA11726.1| sodium/hydrogen exchanger [Roseobacter sp. CCS2] ZP_01751418.1 0.005 29% ...

Increased renal sodium absorption by inhibition of prostaglandin synthesis during fasting in healthy man. A possible role of the epithelial sodium channels

Directory of Open Access Journals (Sweden)

Graffe Carolina C

2010-10-01

Full Text Available Abstract Background Treatment with prostaglandin inhibitors can reduce renal function and impair renal water and sodium excretion. We tested the hypotheses that a reduction in prostaglandin synthesis by ibuprofen treatment during fasting decreased renal water and sodium excretion by increased absorption of water and sodium via the aquaporin2 water channels and the epithelial sodium channels. Methods The effect of ibuprofen, 600 mg thrice daily, was measured during fasting in a randomized, placebo-controlled, double-blinded crossover study of 17 healthy humans. The subjects received a standardized diet on day 1, fasted at day 2, and received an IV infusion of 3% NaCl on day 3. The effect variables were urinary excretions of aquaporin2 (u-AQP2, the beta-fraction of the epithelial sodium channel (u-ENaCbeta, cyclic-AMP (u-cAMP, prostaglandin E2 (u-PGE2. Free water clearance (CH2O, fractional excretion of sodium (FENa, and plasma concentrations of vasopressin, angiotensin II, aldosterone, atrial-, and brain natriuretic peptide. Results Ibuprofen decreased u-AQP2, u-PGE2, and FENa at all parts of the study. During the same time, ibuprofen significantly increased u-ENaCbeta. Ibuprofen did not change the response in p-AVP, u-c-AMP, urinary output, and free water clearance during any of these periods. Atrial-and brain natriuretic peptide were higher. Conclusion During inhibition of prostaglandin synthesis, urinary sodium excretion decreased in parallel with an increase in sodium absorption and increase in u-ENaCbeta. U-AQP2 decreased indicating that water transport via AQP2 fell. The vasopressin-c-AMP-axis did not mediate this effect, but it may be a consequence of the changes in the natriuretic peptide system and/or the angiotensin-aldosterone system Trial Registration Clinical Trials Identifier: NCT00281762

Steam generators of Phenix: Measurement of the hydrogen concentration in sodium for detecting water leaks in the steam generator tubes

International Nuclear Information System (INIS)

Cambillard, E.; Lacroix, A.; Langlois, J.; Viala, J.

1975-01-01

The Phenix secondary circuits are provided with measurement systems of hydrogen concentration in sodium, that allow for the detection of possible water leaks in steam generators and the location of a faulty module. A measurement device consists of : a detector with nickel membranes of 0, 3 mm wall thickness, an ion pump with a 200 l/s flow rate, a quadrupole mass spectrometer and a calibrated hydrogen leak. The temperature correction is made automatically. The main tests carried out on the leak detection systems are reported. Since the first system operation (October 24, 1973), the measurements allowed us to obtain the hydrogen diffusion rates through the steam generator tube walls. (author)

Functional Dynamics of Hexameric Helicase Probed by Hydrogen Exchange and Simulation

Science.gov (United States)

Radou, Gaël; Dreyer, Frauke N.; Tuma, Roman; Paci, Emanuele

2014-01-01

The biological function of large macromolecular assemblies depends on their structure and their dynamics over a broad range of timescales; for this reason, it is a significant challenge to investigate these assemblies using conventional experimental techniques. One of the most promising experimental techniques is hydrogen-deuterium exchange detected by mass spectrometry. Here, we describe to our knowledge a new computational method for quantitative interpretation of deuterium exchange kinetics and apply it to a hexameric viral helicase P4 that unwinds and translocates RNA into a virus capsid at the expense of ATP hydrolysis. Room-temperature dynamics probed by a hundred nanoseconds of all-atom molecular dynamics simulations is sufficient to predict the exchange kinetics of most sequence fragments and provide a residue-level interpretation of the low-resolution experimental results. The strategy presented here is also a valuable tool to validate experimental data, e.g., assignments, and to probe mechanisms that cannot be observed by x-ray crystallography, or that occur over timescales longer than those that can be realistically simulated, such as the opening of the hexameric ring. PMID:25140434

Inhibition of hydrogen oxidation by HBr and Br₂

DEFF Research Database (Denmark)

Dixon-Lewis, Graham; Marshall, Paul; Ruscic, Branko

2012-01-01

O. Ab initio calculations were used to obtain rate coefficients for selected reactions of HBr and HOBr, and the hydrogen/bromine/oxygen reaction mechanism was updated. The resulting model was validated against selected experimental data from the literature and used to analyze the effect of HBr and Br2......The high-temperature bromine chemistry was updated and the inhibition mechanisms involving HBr and Br2 were re-examined. The thermochemistry of the bromine species was obtained using the Active Thermochemical Tables (ATcT) approach, resulting in improved data for, among others, Br, HBr, HOBr and Br...... on laminar, premixed hydrogen flames. Our work shows that hydrogen bromide and molecular bromine act differently as inhibitors in flames. For HBr, the reaction HBr+H⇌H2+Br (R2) is rapidly equilibrated, depleting HBr in favor of atomic Br, which is the major bromine species throughout the reaction zone...

Corrosion Inhibition of Mild Steel in Hydrochloric Acid by Sodium Lauryl Sulfate (SLS)

OpenAIRE

Atul Kumar

2008-01-01

Effect of Sodium Lauryl Sulfate (SLS), a surfactant on corrosion of mild steel in 1 M hydrochloric acid was studied using three techniques namely: weight loss, electrochemical polarization and metallurgical research microscopy. Results obtained reveal that SLS is good inhibitor and shows very good corrosion inhibition efficiency (IE). The IE was found to vary with concentration of inhibitor and temperature. The electrochemical polarization result revealed that SLS is anodic in nature.

Sodium pool fire analysis of sodium-cooled fast reactor by calculation

International Nuclear Information System (INIS)

Yu Hong; Xu Mi; Jin Degui

2002-01-01

Theoretical models were established according to the characteristic of sodium pool fire, and the SPOOL code was created independently. Some transient processes in sodium pool fire were modeled, including chemical reaction of sodium and oxygen; sodium combustion heat transfer modes in several kids of media; production, deposition and discharge of sodium aerosol; mass and energy exchange between different media in different ventilating conditions. The important characteristic parameters were calculated, such as pressure and temperature of gas, temperature of building materials, mass concentration of sodium aerosol, and so on. The SPOOL code, which provided available safety analysis tool for sodium pool fire accidents in sodium-cooled fast reactor, was well demonstrated with experimental data

Corrosion of Steels in the Vicinity of a Sodium-Water Reaction

Energy Technology Data Exchange (ETDEWEB)

Davies, R. A.; Bray, J. A.; Lyons, J. M. [U.K. Atomic Energy Authority, Dounreay Experimental Reactor Establishment, Thurso, Caithness (United Kingdom)

1967-06-15

Rapid corrosion of steels in the vicinity of a sodium-water reaction could lead to a major reaction in a sodium-water heat exchanger. An investigation of the magnitude of the corrosion problem has been carried out under conditions simulating both a small water leak and a full size pipe burst, and further tube failures have been obtained. These experiments were carried out on a sodium rig which could accommodate simple full-scale models of sections of heat exchanger, and up to 70 lb of water was injected into 700 lb of sodium in 9.0s. The corrosion phenomena have also been investigated on a small scale under more controllable conditions by pumping water at normal pressures into a pot of sodium. With a flow-rate of 1 ml/min corrosion rates in excess of 0.005 in./min have been obtained. The effect of various parameters on the corrosion rate has been studied, and a comparison has been made of the corrosion rates obtained with a variety of steels. The corrosion appears to be a direct result of conditions during the reaction, and the appearance of the specimen and pattern of damage suggests that the main effect is concentrated where the sodium water reaction front impinges on the metal surface. The corrosion rates are very much lower with stainless steel and nickel alloys than with ferritic materials, and suggest that the phenomena are associated with the formation of (Na{sub 2}O){sub 2}FeO. Iron powder has also been observed in the vicinity of the reaction which would suggest that this is reduced at a later stage, either as a result of the hydrogen produced during reaction, or by thermal cycling. (author)

Inhibition of filiform corrosion on organic-coated AA2024-T3 by smart-release cation and anion-exchange pigments

International Nuclear Information System (INIS)

Williams, G.; McMurray, H.N.

2012-01-01

Highlights: ► Filiform corrosion (FFC) inhibition by various smart-release pigments was evaluated by SKP. ► Rare earth cation-containing pigments were ineffective at halting FFC propagation. ► Metal oxo-anions and organic copper-specific agents were exchanged into hydrotalcite. ► Effective inhibition of FFC was demonstrated by anions which stopped copper re-plating. - Abstract: In-coating cation and anion exchange pigments are studied with respect to their ability to inhibit chloride-induced filiform corrosion (FFC) on organic-coated AA2024-T3 aluminium alloy substrates. In-situ scanning Kelvin probe potentiometry is used to quantify both underfilm potentials associated with populations of propagating corrosion filaments and the kinetics of coating disbondment. Smart-release bentonite pigments containing exchangeable cerium (III) and yttrium (III) cations are shown to be largely ineffective in reducing rates of FFC propagation. The reasons for this are discussed in terms of the chemistry of the electrolyte-filled corrosion filament head. In contrast, anion-exchange hydrotalcite (HT) based pigments are highly effective inhibitors of FFC. A comparison of the extent of FFC observed for various inorganic exchangeable anions is made with as-received HT comprising carbonate anions. Of the anions evaluated, exchangeable chromate unsurprisingly provides the highest FFC inhibition efficiency. It is also demonstrated that exchanging the native carbonate ions for certain organic species which act as complexing agents for copper ions, gives rise to an equivalent level of FFC inhibition. The implication of these findings with respect to the mechanism of FFC on copper containing aluminium alloys is considered.

General Tritium Labelling of Gentamicin C by catalytic hydrogen exchange Reaction with Tritiated Water

International Nuclear Information System (INIS)

Suarez, C.; Diaz, D.; Paz, D.

1991-01-01

Gentamicin C was labelled with tritium by means of a PtO2 catalyzed hydrogen exchange reaction. Under the conditions of the exchange (100 mg of gentamicin, basic form, 0,3 ml H2O-3H, and 50 mg of prereduced PtO2) the radiochemical yield was 0,24, 0,38 and 0,48 % at 120 degree celsius, for 8, 16 and 24 hours respectively. Chemical yield for purified gentamicin was about 60 %. Purification was accomplished with a cellulose column eluted with the lower phase of chloroform-methanol 17 % ammonium hydroxide (2:1:1, v/v) . Chemical purity, determined by HPLC, was 96,5 % and radiochemical one was 95. Main exchange degradation products show biological activity. (Author) 12 refs

General Tritium labelling of gentamicin C by catalytic hydrogen exchange reaction with tritiated water

International Nuclear Information System (INIS)

Suarez, C.; Diaz, D.

1991-01-01

Gentamicin C was labelled with tritium by means of a PtO 2 catalized hydrogen exchange reaction. Under the conditions of the exchange (100 mg of gentamicin, basic form, 0,3 ml H 2 O- 3 H, and 50 mg of prereduced PtO 2 ) the radiochemical yield was 0,24, 0,38 and 0,48 % at 120 o C, for 8, 16 and 24 hours respectively. Chemical yield for purified gentamicin was about 60 %. Purification was accoumplished with a cellulose column eluted with the lower phase of chloroform-methanol 17 % ammonium hydroxide (2:1:1, v/v). Chemical purity, determined by HPLC, was 96,5 % and radiochemical one was 95 % . Main exchange degradation products show biological activity. (Author). 12 refs

Improved protein hydrogen/deuterium exchange mass spectrometry platform with fully automated data processing.

Science.gov (United States)

Zhang, Zhongqi; Zhang, Aming; Xiao, Gang

2012-06-05

Protein hydrogen/deuterium exchange (HDX) followed by protease digestion and mass spectrometric (MS) analysis is accepted as a standard method for studying protein conformation and conformational dynamics. In this article, an improved HDX MS platform with fully automated data processing is described. The platform significantly reduces systematic and random errors in the measurement by introducing two types of corrections in HDX data analysis. First, a mixture of short peptides with fast HDX rates is introduced as internal standards to adjust the variations in the extent of back exchange from run to run. Second, a designed unique peptide (PPPI) with slow intrinsic HDX rate is employed as another internal standard to reflect the possible differences in protein intrinsic HDX rates when protein conformations at different solution conditions are compared. HDX data processing is achieved with a comprehensive HDX model to simulate the deuterium labeling and back exchange process. The HDX model is implemented into the in-house developed software MassAnalyzer and enables fully unattended analysis of the entire protein HDX MS data set starting from ion detection and peptide identification to final processed HDX output, typically within 1 day. The final output of the automated data processing is a set (or the average) of the most possible protection factors for each backbone amide hydrogen. The utility of the HDX MS platform is demonstrated by exploring the conformational transition of a monoclonal antibody by increasing concentrations of guanidine.

Online Simultaneous Hydrogen/Deuterium Exchange of Multitarget Gas-Phase Molecules by Electrospray Ionization Mass Spectrometry Coupled with Gas Chromatography.

Science.gov (United States)

Jeong, Eun Sook; Cha, Eunju; Cha, Sangwon; Kim, Sunghwan; Oh, Han Bin; Kwon, Oh-Seung; Lee, Jaeick

2017-11-21

In this study, a hydrogen/deuterium (H/D) exchange method using gas chromatography-electrospray ionization/mass spectrometry (GC-ESI/MS) was first investigated as a novel tool for online H/D exchange of multitarget analytes. The GC and ESI source were combined with a homemade heated column transfer line. GC-ESI/MS-based H/D exchange occurs in an atmospheric pressure ion source as a result of reacting the gas-phase analyte eluted from GC with charged droplets of deuterium oxide infused as the ESI spray solvent. The consumption of the deuterated solvent at a flow rate of 2 μL min -1 was more economical than that in online H/D exchange methods reported to date. In-ESI-source H/D exchange by GC-ESI/MS was applied to 11 stimulants with secondary amino or hydroxyl groups. After H/D exchange, the spectra of the stimulants showed unexchanged, partially exchanged, and fully exchanged ions showing various degrees of exchange. The relative abundances corrected for naturally occurring isotopes of the fully exchanged ions of stimulants, except for etamivan, were in the range 24.3-85.5%. Methylephedrine and cyclazodone showed low H/D exchange efficiency under acidic, neutral, and basic spray solvent conditions and nonexchange for etamivan with an acidic phenolic OH group. The in-ESI-source H/D exchange efficiency by GC-ESI/MS was sufficient to determine the number of hydrogen by elucidation of fragmentation from the spectrum. Therefore, this online H/D exchange technique using GC-ESI/MS has potential as an alternative method for simultaneous H/D exchange of multitarget analytes.

Corrosion Inhibition of Mild Steel in Hydrochloric Acid by Sodium Lauryl Sulfate (SLS

Directory of Open Access Journals (Sweden)

Atul Kumar

2008-01-01

Full Text Available Effect of Sodium Lauryl Sulfate (SLS, a surfactant on corrosion of mild steel in 1 M hydrochloric acid was studied using three techniques namely: weight loss, electrochemical polarization and metallurgical research microscopy. Results obtained reveal that SLS is good inhibitor and shows very good corrosion inhibition efficiency (IE. The IE was found to vary with concentration of inhibitor and temperature. The electrochemical polarization result revealed that SLS is anodic in nature.

Conformational analysis of g protein-coupled receptor signaling by hydrogen/deuterium exchange mass spectrometry.

Science.gov (United States)

Li, Sheng; Lee, Su Youn; Chung, Ka Young

2015-01-01

Conformational change and protein-protein interactions are two major mechanisms of membrane protein signal transduction, including G protein-coupled receptors (GPCRs). Upon agonist binding, GPCRs change conformation, resulting in interaction with downstream signaling molecules such as G proteins. To understand the precise signaling mechanism, studies have investigated the structural mechanism of GPCR signaling using X-ray crystallography, nuclear magnetic resonance (NMR), or electron paramagnetic resonance. In addition to these techniques, hydrogen/deuterium exchange mass spectrometry (HDX-MS) has recently been used in GPCR studies. HDX-MS measures the rate at which peptide amide hydrogens exchange with deuterium in the solvent. Exposed or flexible regions have higher exchange rates and excluded or ordered regions have lower exchange rates. Therefore, HDX-MS is a useful tool for studying protein-protein interfaces and conformational changes after protein activation or protein-protein interactions. Although HDX-MS does not give high-resolution structures, it analyzes protein conformations that are difficult to study with X-ray crystallography or NMR. Furthermore, conformational information from HDX-MS can help in the crystallization of X-ray crystallography by suggesting highly flexible regions. Interactions between GPCRs and downstream signaling molecules are not easily analyzed by X-ray crystallography or NMR because of the large size of the GPCR-signaling molecule complexes, hydrophobicity, and flexibility of GPCRs. HDX-MS could be useful for analyzing the conformational mechanism of GPCR signaling. In this chapter, we discuss details of HDX-MS for analyzing GPCRs using the β2AR-G protein complex as a model system. © 2015 Elsevier Inc. All rights reserved.

On the mechanism of ion exchange in zirconium phosphates

International Nuclear Information System (INIS)

Kullberg, L.; Clearfield, A.

1981-01-01

An equilibrium study of the Na + -Cs + -H + exchange on crystalline α-zirconium phosphate has been carried out. Isotherms for the ion exchange have been determined and phases formed during the exchange have been identified. The surface groups of the exchanger were found to greatly prefer cesium to sodium. For exchange in the interior, cesium was found to be preferred to sodium for 0 to 50% of exchange, while sodium is slightly preferred to cesium for the second half of exchange. The influence of surface equilibria on the total exchange mechanism is discussed. (author)

Methods for the sodium cooled fast reactor fire safety provisions

International Nuclear Information System (INIS)

Gryaznov, B.V.; Dergachev, N.P.

1983-01-01

Problems of fire safety provision on NPPs with sodium cooled fast reactor are under discussion. Methods of sodium leak localization, measures eliminating sodium flaring up during leaks and main means of sodium fire extinguishing are considered. An extinguishing of sodium flaring up is performed by means of sodium temperatUre decrease and by limitation of hydrogen access to the flaring up surface. A conclusion is made that the most effective methods of extinguishing are the following: self-extinguishing (due to hydrogen burning out in a limiting volume); extinguishing by a gas mixture of nitrogen and carbonic acid (initial filling and blowing of rooms during sodium flaring up); extinguishing by special powders

The origins of enhanced activity in factor VIIa analogs and the interplay between key allosteric sites revealed by hydrogen exchange mass spectrometry

DEFF Research Database (Denmark)

Rand, Kasper D; Andersen, Mette D; Olsen, Ole H

2008-01-01

Factor VIIa (FVIIa) circulates in the blood in a zymogen-like state. Only upon association with membrane-bound tissue factor (TF) at the site of vascular injury does FVIIa become active and able to initiate blood coagulation. Here we used hydrogen exchange monitored by mass spectrometry to invest......Factor VIIa (FVIIa) circulates in the blood in a zymogen-like state. Only upon association with membrane-bound tissue factor (TF) at the site of vascular injury does FVIIa become active and able to initiate blood coagulation. Here we used hydrogen exchange monitored by mass spectrometry...... to investigate the conformational effects of site-directed mutagenesis at key positions in FVIIa and the origins of enhanced intrinsic activity of FVIIa analogs. The differences in hydrogen exchange of two highly active variants, FVIIa(DVQ) and FVIIa(VEAY), imply that enhanced catalytic efficiency was attained...

NCBI nr-aa BLAST: CBRC-DDIS-05-0125 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-DDIS-05-0125 ref|ZP_01460652.1| sodium/hydrogen exchanger [Stigmatella auranti...aca DW4/3-1] gb|EAU68588.1| sodium/hydrogen exchanger [Stigmatella aurantiaca DW4/3-1] ZP_01460652.1 1e-92 37% ...

Inhibition of several enzymes by gold compounds. II. beta-Glucuronidase, acid phosphatase and L-malate dehydrogenase by sodium thiomalatoraurate (I), sodium thiosulfatoaurate (I) and thioglucosoaurate (I).

Science.gov (United States)

Lee, M T; Ahmed, T; Haddad, R; Friedman, M E

1989-01-01

Bovine liver beta-D-glucuronide glucuronohydrolase, EC 3.2.1.32), wheat germ acid phosphatase (orthophosphoric monoesterphosphohydrolase, EC 3.1.3.2) and bovine liver L-malate dehydrogenase (L-malate: NAD oxidoreductase, EC 1.1.1.37) were inhibited by a series of gold (I) complexes that have been used as anti-inflammatory drugs. Both sodium thiosulfatoaurate (I) (Na AuTs) and sodium thiomalatoraurate (NaAuTM) effectively inhibited all three enzymes, while thioglucosoaurate (I) (AuTG) only inhibited L-malate dehydrogenase. The equilibrium constants (K1) ranged from nearly 4000 microM for the NaAuTM-beta-glucuronidase interaction to 24 microM for the NaAuTS-beta-glucuronidase interaction. The rate of covalent bond formation (kp) ranged from 0.00032 min-1 for NaAuTM-beta-glucuronidase formation to 1.7 min-1 for AuTG-L-malate dehydrogenase formation. The equilibrium data shows that the gold (I) drugs bind by several orders lower than the gold (III) compounds, suggesting a significantly stronger interaction between the more highly charged gold ion and the enzyme. Yet the rate of covalent bond formation depends as much on the structure of the active site as upon the lability of the gold-ligand bond. It was also observed that the more effective the gold inhibition the more toxic the compound.

Infusing Sodium Bicarbonate Suppresses Hydrogen Peroxide Accumulation and Superoxide Dismutase Activity in Hypoxic-Reoxygenated Newborn Piglets

OpenAIRE

Liu, Jiang-Qin; Manouchehri, Namdar; Lee, Tze-Fun; Yao, Mingzhu; Bigam, David L.; Cheung, Po-Yin

2012-01-01

Background The effectiveness of sodium bicarbonate (SB) has recently been questioned although it is often used to correct metabolic acidosis of neonates. The aim of the present study was to examine its effect on hemodynamic changes and hydrogen peroxide (H2O2) generation in the resuscitation of hypoxic newborn animals with severe acidosis. Methods Newborn piglets were block-randomized into a sham-operated control group without hypoxia (n = 6) and two hypoxia-reoxygenation groups (2 h normocap...

Experimental investigations and modelling of sodium-concrete interaction

International Nuclear Information System (INIS)

Schultheiss, G.F.; Deeg, H.J.

1990-01-01

The use of sodium as a coolant in liquid metal fast breeder reactors, fusion reactors, and solar plants requires special consideration of its chemical reactivity and related safety problems in the case of sodium leckage. On contact between hot sodium and concrete an interaction takes place resulting in energy release and hydrogen generation, which may contribute to containment loading by pressurization in a hypothetical accident situation. For this reason, sodium-concrete interactions were investigated experimentally and theoretically. The experiments revealed important effects of quartzitic material within the concrete and of the sodium temperature on the interaction mechanisms, the energy release and the consequent hydrogen production. The numerical model shows good agreement with the experimental results. (orig.) [de

Quantification of protein backbone hydrogen-deuterium exchange rates by solid state NMR spectroscopy

International Nuclear Information System (INIS)

Lopez del Amo, Juan-Miguel; Fink, Uwe; Reif, Bernd

2010-01-01

We present the quantification of backbone amide hydrogen-deuterium exchange rates (HDX) for immobilized proteins. The experiments make use of the deuterium isotope effect on the amide nitrogen chemical shift, as well as on proton dilution by deuteration. We find that backbone amides in the microcrystalline α-spectrin SH3 domain exchange rather slowly with the solvent (with exchange rates negligible within the individual 15 N-T 1 timescales). We observed chemical exchange for 6 residues with HDX exchange rates in the range from 0.2 to 5 s -1 . Backbone amide 15 N longitudinal relaxation times that we determined previously are not significantly affected for most residues, yielding no systematic artifacts upon quantification of backbone dynamics (Chevelkov et al. 2008b). Significant exchange was observed for the backbone amides of R21, S36 and K60, as well as for the sidechain amides of N38, N35 and for W41ε. These residues could not be fit in our previous motional analysis, demonstrating that amide proton chemical exchange needs to be considered in the analysis of protein dynamics in the solid-state, in case D 2 O is employed as a solvent for sample preparation. Due to the intrinsically long 15 N relaxation times in the solid-state, the approach proposed here can expand the range of accessible HDX rates in the intermediate regime that is not accessible so far with exchange quench and MEXICO type experiments.

Design of a trial evaluating myocardial cell protection with cariporide, an inhibitor of the transmembrane sodium-hydrogen exchanger: the Guard During Ischemia Against Necrosis (GUARDIAN trial

Directory of Open Access Journals (Sweden)

Schroeder John S

2000-08-01

Full Text Available Synopsis Background Direct myocardial cell protection in patients with unstable angina or evolving myocardial infarction (MI could prevent cell necrosis or reduce its extent, and minimize the risk of MI and death associated with percutaneous coronary interventions (PCIs and coronary artery bypass surgery. The myocardial NHE plays a critical role in mediating the progression of ischemia to necrosis by promoting intracellular accumulation of sodium and calcium in exchange for hydrogen. Blockage of the system in various experimental models of ischemia and reperfusion had a strong antinecrotic effect. The present paper describes a trial that was intended to investigate the potential clinical benefit of cariporide, a potent and selective inhibitor of the NHE, in a large spectrum of at-risk patients. Trial design The GUARDIAN trial was a multicenter, double-blind, randomized, four-arm trial that compared three cariporide dosages with placebo in patients with unstable angina and non-ST-segment elevation myocardial infarction (UA/NSTEMI and in patients undergoing a high-risk PCI or coronary artery bypass surgery. A total of 11 590 patients with one of the three possible entry diagnoses were enroled in 23 countries. The trial was designed as a combined phase 2/phase 3 study. The primary objective was to evaluate the efficacy of cariporide in reducing all-cause mortality and/or MI across the various entry populations 36 days after randomization. Three different doses of cariporide were compared with placebo. Secondary end-points were death or non-fatal MI at 10 days and 6 months, and cardiac events related to left ventricular dysfunction. The extent of MI was also assessed by peak elevation in creatinine kinase (CK-MB and a ratio of peak elevation to normal values. The sample size was driven by a total event rate of 1200 patients experiencing a primary end-point, powered to detect a 25% risk reduction in any of the three treatment groups compared with

Hydrogen isotope exchange of organic compounds in dilute acid at elevated temperatures

International Nuclear Information System (INIS)

Werstiuk, N.H.

1987-01-01

Introduction of one or more deuterium (or tritium) atoms into organic molecules can be accomplished in many ways depending on the nature of the substrate and the extent and sterochemistry of deuteriation or tritiation required. Some of the common methods include acid- and base-catalyzed exchange of carbonyl compounds, metal hydride reductions, dissolving metal reductions, catalytic reduction of double bonds, chromatographic exchange, homogeneous and heterogeneous metal-catalyzed exchange, base-catalyzed exchange of carbon acids other than carbonyl compounds and acid-catalyzed exchange via electrophilic substitution. Only the latter three methods have been used for perdeuteriation of organic compounds. A very useful compendium of labeling methods with examples has been available to chemists for some time. Although metal-catalyzed exchange has been used extensively, the method suffers from some deficiencies: irreproducibility of catalyst surfaces, catalyst poisoning, side reactions such as coupling and hydrogenolysis of labile groups and low deuterium incorporation. Usually a number of cycles are required with fresh catalyst and fresh deuterium source to achieve substantial isotope incorporation. Acid-catalyzed exchange of aromatics and alkenes, strongly acidic media such as liquid DBr, concentrated DBr, acetic acid/stannic chloride, concentrated D 3 PO 4 , concentrated DC1, D 3 PO 4 /BF 3 SO 2 , 50-80% D 2 SO 4 and DFSO 4 /SbF 5 at moderate temperatures (<100 degrees) have been used to effect exchange. The methods are not particularly suitable for large scale deuteriations because of the cost and the fact that the recovery and upgrading of the diluted deuterium pool is difficult. This paper describes the hydrogen isotope exchange of a variety of organic compounds in dilute aqueous acid (0.1-0.5 M) at elevated temperatures (150-300 degrees)

Recoverying device for sodium vapor in inert gas

Energy Technology Data Exchange (ETDEWEB)

Nakagawa, Tamotsu; Nagashima, Ikuo

1992-11-06

A multi-pipe type heat exchanger for cooling an inert gas and a mist trap connected to the inert gas exit of the heat exchanger are disposed. A mist filter having bottomed pipes made of an inert gas-permeable sintered metal is disposed in the mist trap, and an inert gas discharge port is disposed at the upper side wall. With such a constitution, a high temperature inert gas containing sodium vapors can be cooled efficiently by the multi-pipe type heat exchanger capable of easy temperature control, thereby converting sodium vapors into mists, and the inert gas containing sodium mists can be flown into the mist trap. Sodium mists are collected by the mist filter and sodium mists flown down are discharged from the discharge port. With such procedures, a great amount of the inert gas containing sodium vapors can be processed continuously. (T.M.).

Poly[μ-(1-azaniumylethane-1,1-diyl)- bis(hydrogen phosphonato)sodium]: A powder X-ray diffraction study

International Nuclear Information System (INIS)

Rukiah, M.; Assaad, T.

2015-01-01

The title two-dimensional coordination polymer, [Na(C2H8NO6P2)]n, was characterized using powder X-ray diffraction data and its structure refined using the Rietveld method. The asymmetric unit contains one Na(+) cation and one (1-azaniumylethane-1,1-diyl)bis(hydrogen phosphonate) anion. The central Na(+) cation exhibits distorted octahedral coordination geometry involving two deprotonated O atoms, two hydroxy O atoms and two double-bonded O atoms of the bisphosphonate anion. Pairs of sodium-centred octahedra share edges and the pairs are in turn connected to each other by the biphosphonate anion to form a two-dimensional network parallel to the (001) plane. The polymeric layers are connected by strong O-H...O hydrogen bonding between the hydroxy group and one of the free O atoms of the bisphosphonate anion to generate a three-dimensional network. Further stabilization of the crystal structure is achived by N-H...O and O-H...O hydrogen bonding.(author)

Hydrophobic catalyst mixture for the isotopic exchange reaction between hydrogen and water

Energy Technology Data Exchange (ETDEWEB)

Paek, S.; Ahn, D. H.; Choi, H. J.; Kim, K. R.; Lee, M.; Yim, S. P.; Chung, H. [KAERI, Taejon (Korea, Republic of)

2005-11-15

Pt/SDBC catalyst, which is used for the hydrogen-water isotopic exchange reaction, was prepared. The various properties of the catalyst, such as the thermal stability, pore structure and the platinum dispersion, were investigated. A hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of the WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities.

Hydrophobic catalyst mixture for the isotopic exchange reaction between hydrogen and water

International Nuclear Information System (INIS)

Paek, S.; Ahn, D. H.; Choi, H. J.; Kim, K. R.; Lee, M.; Yim, S. P.; Chung, H.

2005-01-01

Pt/SDBC catalyst, which is used for the hydrogen-water isotopic exchange reaction, was prepared. The various properties of the catalyst, such as the thermal stability, pore structure and the platinum dispersion, were investigated. A hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of the WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities

A Small-Scale Capsule Test for Investigating the Sodium-Carbon Dioxide Reaction

International Nuclear Information System (INIS)

Kim, B. H.; Choi, J. H.; Suk, S. D.; Kim, J. M.; Choi, B. H.; Kim, B. H.; Hahn, D. H.

2007-01-01

The utilization of modular sodium-to-supercritical CO 2 heat exchangers may yield significant improvements for an overall plant energy utilization. The consequences of a failure of the sodium CO 2 heat exchanger boundary, however, would involve the blowdown and intermixing of high-pressure CO 2 in a sodium pool, causing a pressurization which may threaten the structural integrity of the heat exchanger. Available data seems to indicate that the chemical reaction between sodium and CO 2 would likely produce sodium oxides, sodium carbonate, carbon and carbon monoxide. Information on the kinetics of the sodium-CO 2 reaction is virtually non-existent

The Kinetics of Ouabain Inhibition and the Partition of Rubidium Influx in Human Red Blood Cells

Science.gov (United States)

Beauge, L. A.; Adragna, Norma

1971-01-01

In the development of ouabain inhibition of rubidium influx in human red blood cells a time lag can be detected which is a function of at least three variables: the concentrations of external sodium, rubidium, and ouabain. The inhibition is antagonized by rubidium and favored by sodium. Similar considerations could be applied to the binding of ouabain to membrane sites. The total influx of rubidium as a function of external rubidium concentration can be separated into two components: (a) a linear uptake not affected by external sodium or ouabain and not requiring an energy supply, and (b) a saturable component. The latter component, on the basis of the different effects of the aforementioned factors, can be divided into three fractions. The first is ouabain-sensitive, inhibited by external sodium at low rubidium, and requires an energy supply; this represents about 70–80% of the total uptake and is related to the active sodium extrusion mechanism. The second is ouabain-insensitive, activated by external sodium over the entire range of rubidium concentrations studied, and dependent on internal ATP; this represents about 15% of the total influx; it could be coupled to an active sodium extrusion or belong to a rubidium-potassium exchange. The third, which can be called residual influx, is ouabain-insensitive, unaffected by external sodium, and independent of internal ATP; this represents about 10–20% of the total influx. PMID:5553102

The driving force of the Na+/Ca2+-exchanger during metabolic inhibition

NARCIS (Netherlands)

Baartscheer, Antonius; Schumacher, Cees A.; Coronel, Ruben; Fiolet, Jan W. T.

2011-01-01

Objective: Metabolic inhibition causes a decline in mechanical performance and, if prolonged, myocardial contracture and cell death. The decline in mechanical performance is mainly due to altered intracellular calcium handling, which is under control of the Na+/Ca2+-exchanger (NCX) The driving force

Modified hydrogenated PBLH copolymer synthesis with styrene for proton exchange membranes fuel cell application

International Nuclear Information System (INIS)

Ferraz, Fernando A.; Oliveira, Angelo R.S.; Rodrigues, Maraiza F.; Groetzner, Mariana B.; Cesar-Oliveira, Maria Aparecida F.; Cantao, Mauricio P.

2005-01-01

Polymers used as electrolyte in fuel cells are expected to have functional groups in their structure which are responsible for proton conductivity. Since the use of hydroxylated liquid polybutadiene (PBLH) has not been mentioned in the literature as an ion exchange membrane for fuel cell application (PEMFC), and its structure can be modified for a later sulfonation, it has been studied. In this work, PBLH was modified through a hydrogenation reaction. Furthermore, hydrogenated polymeric esters were obtained by esterification and transesterification reactions (PBLH- estearate and PBLH- methacrylate). Reacting the PBLH methacrylate with styrene, it was generated a copolymer with appropriated structure for sulfonation, justifying researches for fuel cell. (author)

A trap activation model for hydrogen retention and isotope exchange in some refractory materials

International Nuclear Information System (INIS)

Brice, D.K.; Doyle, B.L.

1982-01-01

Our recently-developed Local Mixing Model (LMM) has been successful in describing and predicting the properties of hydrogen retention and isotope exchange for a variety of refractory materials. For some materials, however, the detailed predictions of the LMM are not observed. A Trap Activation Model (TAM) is proposed here to account for the observed departures from the LMM. Comparison of experimental room temperature saturation depth profiles for H + →Si with the predictions of TAM suggests that the hydrogen traps are multiple-vacancy complexes in this system. The observed profiles result from a beam-induced competition between trap creation/annihilation and H-trapping/detrapping. (orig.)

Hydrogen vacancies facilitate hydrogen transport kinetics in sodium hydride nanocrystallites

NARCIS (Netherlands)

Singh, S.; Eijt, S.W.H.

2008-01-01

We report ab initio calculations based on density-functional theory, of the vacancy-mediated hydrogen migration energy in bulk NaH and near the NaH(001) surface. The estimated rate of the vacancy mediated hydrogen transport, obtained within a hopping diffusion model, is consistent with the reaction

Quasiclassical trajectory study of the molecular beam kinetics of the deuterium atom--hydrogen halide exchange reactions

International Nuclear Information System (INIS)

Raff, L.M.; Suzukawa, H.H. Jr.; Thompson, D.L.

1975-01-01

Unadjusted quasiclassical trajectory computations have been carried out to simulate the molecular beam scattering of thermal D atom beams at 2800 degreeK crossed with beams of HCl and HI at 250 degreeK. Total reaction cross sections, energy partitioning distributions, and differential scattering cross sections have been computed for the exchange reactions D+HCl → DCl+H and D+HI → DI+H while total reaction cross sections are reported for the corresponding abstractions, i.e., D+HCl → HD+Cl and D+HI → HD+I. For the exchange reactions, the computed reaction cross sections are within the range estimated from the crossed beam experiments. The calculated average energy partitioned into relative translational motion of products is in near quantitative agreement with the beam results, and the predicted differential scattering cross sections appear to be in qualitative accord with the beam experiments. The over-all agreement between theory and experiment indicates that previously computed values for the thermal rate coefficients for the exchange reactions are of the right order and that a systematic error exists in the interpretation of photolysis data in the hydrogen--hydrogen halide systems

Electrolytic process to produce sodium hypochlorite using sodium ion conductive ceramic membranes

Science.gov (United States)

Balagopal, Shekar; Malhotra, Vinod; Pendleton, Justin; Reid, Kathy Jo

2012-09-18

An electrochemical process for the production of sodium hypochlorite is disclosed. The process may potentially be used to produce sodium hypochlorite from seawater or low purity un-softened or NaCl-based salt solutions. The process utilizes a sodium ion conductive ceramic membrane, such as membranes based on NASICON-type materials, in an electrolytic cell. In the process, water is reduced at a cathode to form hydroxyl ions and hydrogen gas. Chloride ions from a sodium chloride solution are oxidized in the anolyte compartment to produce chlorine gas which reacts with water to produce hypochlorous and hydrochloric acid. Sodium ions are transported from the anolyte compartment to the catholyte compartment across the sodium ion conductive ceramic membrane. Sodium hydroxide is transported from the catholyte compartment to the anolyte compartment to produce sodium hypochlorite within the anolyte compartment.

Deactivation of hydrophobic catalysts for a hydrogen isotope exchange: Application of the time-on-stream theory

International Nuclear Information System (INIS)

Choi, Heui-Joo; Lee, Han Soo; Ahn, Do-Hee; Kim, Jeong-Guk; Kim, Wi-soo; Sohn, SoonHwan

2005-01-01

A recycle reactor was built for the purpose of characterizing newly developed hydrophobic catalysts for a hydrogen isotope exchange. The catalytic rate constants of two types of hydrophobic catalysts were measured at a 100% relative humidity. The catalytic rate constants were measured at 60 deg C for 28 days and both the catalysts showed very high initial catalytic rate constants. The measured deactivation profile showed that the catalytic rate constants of both the catalysts were almost identical for 28 days. The deactivation of the catalysts was modelled based upon the time-on-stream theory. The deactivation profiles of the catalysts were estimated by using the model for a period of three years. The results showed that both the catalysts had a good exchange capacity for hydrogen isotopes and they could be applicable to a tritium removal facility that will be built at the Wolsong nuclear power plants in the near future

Proceedings of the 1st JAEA/KAERI information exchange meeting on HTGR and nuclear hydrogen technology

International Nuclear Information System (INIS)

Sato, Hiroyuki; Sakaba, Nariaki; Nishihara, Tetsuo; Yan, Xing L.; Hino, Ryutaro

2007-03-01

Japan Atomic Energy Agency (JAEA) has completed an implementation with Korea Atomic Energy Research Institute (KAERI) on HTGR and nuclear hydrogen technology, 'The Implementation of Cooperative Program in the Field of Peaceful Uses of Nuclear Energy between KAERI and JAEA. 'To facilitate efficient technology development on HTGR and nuclear hydrogen by the IS process, an information exchange meeting was held at the Oarai Research and Development Center of JAEA on August 28-30, 2006 under Program 13th of the JAEA/KAERI Implementation, 'Development of HTGR and Nuclear Hydrogen Technology'. JAEA and KAERI mutually showed the status and future plan of the HTTR (High-Temperature Engineering Test Reactor) project in Japan and of the NHDD (Nuclear Hydrogen Development and Demonstration) project in Korea, respectively, and discussed collaboration items. This proceedings summarizes all materials of presented technical discussions on HTGR and hydrogen production technology as well as the meeting briefing including collaboration items. (author)

A Small-Scale Capsule Test for Investigating the Sodium-Carbon Dioxide Reaction

Energy Technology Data Exchange (ETDEWEB)

Kim, B. H.; Choi, J. H.; Suk, S. D.; Kim, J. M.; Choi, B. H.; Kim, B. H.; Hahn, D. H

2007-01-15

The utilization of modular sodium-to-supercritical CO{sub 2} heat exchangers may yield significant improvements for an overall plant energy utilization. The consequences of a failure of the sodium CO{sub 2} heat exchanger boundary, however, would involve the blowdown and intermixing of high-pressure CO{sub 2} in a sodium pool, causing a pressurization which may threaten the structural integrity of the heat exchanger. Available data seems to indicate that the chemical reaction between sodium and CO{sub 2} would likely produce sodium oxides, sodium carbonate, carbon and carbon monoxide. Information on the kinetics of the sodium-CO{sub 2} reaction is virtually non-existent.

Experience on sodium removal from various components

Energy Technology Data Exchange (ETDEWEB)

Kamei, M; Kanbe, M; Yagisawa, H; Sasaki, S; Kataoka, H; Fukada, T; Ishii, Y; Saito, R; Mimoto, Y [O-arai Engineering Centre, PNC, Ibaraki-ken, Tokio (Japan)

1978-08-01

Since 1970, OEC (O-arai Engineering Center) has been Investigating the following methods for removal of sodium from the components of sodium plants: steam cleaning for the 50 MW Steam Generator, secondary proto-type pump of 'JOYO' and Dummy fuel assembly of 'JOYO', alcohol cleaning for Sector Model of Intermediate Heat Exchanger (IHX) of 'JOYO', a sector model of Sodium-to-Air cooler of 'JOYO' and a proto-type isolation valve of 'JOYO' and cleaning by vacuumization at high temperature for Regenerative Heat Exchanger. This report describes the outline of the Sodium Disposal Facility and experience of sodium removal processing on the 50 MW Steam Generator, the crevices of the experimental sub-assemblies, the Fuel Handling Machine of 'MONJU' and the Regenerative Heat Exchanger of the Sodium Flow Test Facility. Through these experiences it was noted that, (1) Removal of sodium from crevices such as in bolted joints are very difficult. (2) Consideration is needed in the removal process where material damage might occur from the generation of hydro-oxides. (3) Some detection device to tell the completion of sodium removal as well as the end of reaction is required. (4) Requalification rules should be clarified. Efforts in this direction have been made in the case of a 'JOYO' prototype pump by reinstalling it after sodium removal five times. (author)

Experience on sodium removal from various components

International Nuclear Information System (INIS)

Kamei, M.; Kanbe, M.; Yagisawa, H.; Sasaki, S.; Kataoka, H.; Fukada, T.; Ishii, Y.; Saito, R.; Mimoto, Y.

1978-01-01

Since 1970, OEC (O-arai Engineering Center) has been Investigating the following methods for removal of sodium from the components of sodium plants: steam cleaning for the 50 MW Steam Generator, secondary proto-type pump of 'JOYO' and Dummy fuel assembly of 'JOYO', alcohol cleaning for Sector Model of Intermediate Heat Exchanger (IHX) of 'JOYO', a sector model of Sodium-to-Air cooler of 'JOYO' and a proto-type isolation valve of 'JOYO' and cleaning by vacuumization at high temperature for Regenerative Heat Exchanger. This report describes the outline of the Sodium Disposal Facility and experience of sodium removal processing on the 50 MW Steam Generator, the crevices of the experimental sub-assemblies, the Fuel Handling Machine of 'MONJU' and the Regenerative Heat Exchanger of the Sodium Flow Test Facility. Through these experiences it was noted that, (1) Removal of sodium from crevices such as in bolted joints are very difficult. (2) Consideration is needed in the removal process where material damage might occur from the generation of hydro-oxides. (3) Some detection device to tell the completion of sodium removal as well as the end of reaction is required. (4) Requalification rules should be clarified. Efforts in this direction have been made in the case of a 'JOYO' prototype pump by reinstalling it after sodium removal five times. (author)

Experience on sodium removal from various components

International Nuclear Information System (INIS)

Kamei, M.; Kanbe, M.; Yagisawa, H.; Sasaki, S.; Kataoka, H.

1978-02-01

Since 1970, OEC (O-arai Engineering Center) has been investigating the following methods for removal of sodium from the components of sodium plants: steam cleaning for the 50 MW Steam Generator, secondary proto-type pump of ''JOYO'' and Dummy fuel assembly of ''JOYO'', alcohol cleaning for Sector Model of Intermediate Heat Exchanger (IHX) of ''JOYO'', a sector model of Sodium-to-Air cooler of ''JOYO'' and a proto-type Isolation valve of ''JOYO'' and cleaning by vacuumization at high temperature for Regenerative Heat Exchanger. This report describes the outline of the Sodium Disposal Facility and experience of sodium removal processing on the 50 MW Steam Generator, the crevices of the experimental subassemblies, the Fuel Handling Machine of ''MONJU'' and the Regenerative Heat Exchanger of the Sodium Flow Test Facility. Through these experiences it was noted that, (1) Removal of Sodium from crevices such as in bolted joints are very difficult. (2) Consideration is needed in the removal process where material damage might occur from the generation of hydro-oxides. (3) Some detection device to tell the completion of sodium removal as well as the end of reaction is required. (4) Requalification rules should be clarified. Efforts in this direction have been made in the case of a ''JOYO'' prototype pump by reinstalling it after sodium removal five times. (author)

Dynamics of urokinase receptor interaction with Peptide antagonists studied by amide hydrogen exchange and mass spectrometry

DEFF Research Database (Denmark)

Jørgensen, Thomas J D; Gårdsvoll, Henrik; Danø, Keld

2004-01-01

Using amide hydrogen exchange combined with electrospray ionization mass spectrometry, we have in this study determined the number of amide hydrogens on several peptides that become solvent-inaccessible as a result of their high-affinity interaction with the urokinase-type plasminogen activator...... receptor (uPAR). These experiments reveal that at least six out of eight amide hydrogens in a synthetic nine-mer peptide antagonist (AE105) become sequestered upon engagement in uPAR binding. Various uPAR mutants with decreased affinity for this peptide antagonist gave similar results, thereby indicating...... that deletion of the favorable interactions involving the side chains of these residues in uPAR does not affect the number of hydrogen bonds established by the main chain of the peptide ligand. The isolated growth factor-like domain (GFD) of the cognate serine protease ligand for uPAR showed 11 protected amide...

Factors determining the activity of catalysts of various chemical types in the oxidation of hydrogen. I. Oxidation and isotope exchange of hydrogen on cobalt monoxide-oxide

International Nuclear Information System (INIS)

Polgikh, L.Y.; Golodets, G.I.; Il'chenko, N.I.

1985-01-01

On the basis of data on the kinetics of the reaction 2H 2 + O 2 = 2H 2 O isotope exchange H 2 + D 2 = 2HD under the conditions of oxidative catalysis, and the kinetic isotope effect, a mechanism is proposed for the oxidation of hydrogen on cobalt monoxide-oxide. At low temperatures the reaction proceeds according to a mechanism of alternating reduction-reoxidation of the surface with the participation of hydrogen adsorbed in molecular form; at increased temperature and low P 02 /P /SUB H2/ ratios, a significant contribution to the observed rate is made by a mechanism including dissociative chemisorption of hydrogen

Sodium citrate-assisted anion exchange strategy for construction of Bi2O2CO3/BiOI photocatalysts

International Nuclear Information System (INIS)

Song, Peng-Yuan; Xu, Ming; Zhang, Wei-De

2015-01-01

Highlights: • Heterostructured Bi 2 O 2 CO 3 /BiOI microspheres were prepared via anion exchange. • Sodium citrate-assisted anion exchange for construction of composite photocatalysts. • Bi 2 O 2 CO 3 /BiOI composites show high visible light photocatalytic activity. - Abstract: Bi 2 O 2 CO 3 /BiOI heterojuncted photocatalysts were constructed through a facile partial anion exchange strategy starting from BiOI microspheres and urea with the assistance of sodium citrate. The content of Bi 2 O 2 CO 3 in the catalysts was regulated by modulating the amount of urea as a precursor, which was decomposed to generate CO 3 2− in the hydrothermal process. Citrate anion plays a key role in controlling the morphology and composition of the products. The Bi 2 O 2 CO 3 /BiOI catalysts display much higher photocatalytic activity than pure BiOI and Bi 2 O 2 CO 3 towards the degradation of rhodamine B (RhB) and bisphenol A (BPA). The enhancement of photocatalytic activity of the heterojuncted catalysts is attributed to the formation of p–n junction between p-BiOI and n-Bi 2 O 2 CO 3 , which is favorable for retarding the recombination of photoinduced electron-hole pairs. Moreover, the holes are demonstrated to be the main active species for the degradation of RhB and BPA

Hydrogen Exchange Mass Spectrometry of Functional Membrane-bound Chemotaxis Receptor Complexes

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Koshy, Seena S.; Eyles, Stephen J.; Weis, Robert M.; Thompson, Lynmarie K.

2014-01-01

The transmembrane signaling mechanism of bacterial chemotaxis receptors is thought to involve changes in receptor conformation and dynamics. The receptors function in ternary complexes with two other proteins, CheA and CheW, that form extended membrane-bound arrays. Previous studies have shown that attractant binding induces a small (~2 Å) piston displacement of one helix of the periplasmic and transmembrane domains towards the cytoplasm, but it is not clear how this signal propagates through the cytoplasmic domain to control the kinase activity of the CheA bound at the membrane-distal tip, nearly 200 Å away. The cytoplasmic domain has been shown to be highly dynamic, which raises the question of how a small piston motion could propagate through a dynamic domain to control CheA kinase activity. To address this, we have developed a method for measuring dynamics of the receptor cytoplasmic fragment (CF) in functional complexes with CheA and CheW. Hydrogen exchange mass spectrometry (HDX-MS) measurements of global exchange of CF demonstrate that CF exhibits significantly slower exchange in functional complexes than in solution. Since the exchange rates in functional complexes are comparable to that of other proteins of similar structure, the CF appears to be a well-structured protein within these complexes, which is compatible with its role in propagating a signal that appears to be a tiny conformational change in the periplasmic and transmembrane domains of the receptor. We also demonstrate the feasibility of this protocol for local exchange measurements, by incorporating a pepsin digest step to produce peptides with 87% sequence coverage and only 20% back exchange. This method extends HDX-MS to membrane-bound functional complexes without detergents that may perturb the stability or structure of the system. PMID:24274333

Dual Studies on a Hydrogen-Deuterium Exchange of Resorcinol and the Subsequent Kinetic Isotope Effect

Science.gov (United States)

Giles, Richard; Kim, Iris; Chao, Weyjuin Eric; Moore, Jennifer; Jung, Kyung Woon

2014-01-01

An efficient laboratory experiment has been developed for undergraduate students to conduct hydrogen-deuterium (H-D) exchange of resorcinol by electrophilic aromatic substitution using D[subscript 2]O and a catalytic amount of H[subscript 2]SO[subscript 4]. The resulting labeled product is characterized by [superscript 1]H NMR. Students also…

Co-overexpressing a plasma membrane and a vacuolar membrane sodium/proton antiporter significantly improves salt tolerance in transgenic Arabidopsis plants.

Science.gov (United States)

The Arabidopsis gene AtNHX1 encodes a vacuolar membrane bound sodium/proton (Sodium/Hydrogen) antiporter that transports sodium into the vacuole and exports hydrogen into the cytoplasm. The Arabidopsis gene SOS1 encodes a plasma membrane bound sodium/hydrogen antiporter that exports sodium to the ex...

Gas-Phase Hydrogen-Deuterium Exchange Labeling of Select Peptide Ion Conformer Types: a Per-Residue Kinetics Analysis.

Science.gov (United States)

Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Tafreshian, Amirmahdi; Valentine, Stephen J

2015-07-01

The per-residue, gas-phase hydrogen deuterium exchange (HDX) kinetics for individual amino acid residues on selected ion conformer types of the model peptide KKDDDDDIIKIIK have been examined using ion mobility spectrometry (IMS) and HDX-tandem mass spectrometry (MS/MS) techniques. The [M + 4H](4+) ions exhibit two major conformer types with collision cross sections of 418 Å(2) and 446 Å(2); the [M + 3H](3+) ions also yield two different conformer types having collision cross sections of 340 Å(2) and 367 Å(2). Kinetics plots of HDX for individual amino acid residues reveal fast- and slow-exchanging hydrogens. The contributions of each amino acid residue to the overall conformer type rate constant have been estimated. For this peptide, N- and C-terminal K residues exhibit the greatest contributions for all ion conformer types. Interior D and I residues show decreased contributions. Several charge state trends are observed. On average, the D residues of the [M + 3H](3+) ions show faster HDX rate contributions compared with [M + 4H](4+) ions. In contrast the interior I8 and I9 residues show increased accessibility to exchange for the more elongated [M + 4H](4+) ion conformer type. The contribution of each residue to the overall uptake rate showed a good correlation with a residue hydrogen accessibility score model calculated using a distance from charge site and initial incorporation site for nominal structures obtained from molecular dynamic simulations (MDS).

Time-resolved pulsed hydrogen/deuterium exchange mass spectrometry probes gaseous proteins structural kinetics.

Science.gov (United States)

Rajabi, Khadijeh

2015-01-01

A pulsed hydrogen/deuterium exchange (HDX) method has been developed for rapid monitoring of the exchange kinetics of protein ions with D2O a few milliseconds after electrospray ionization (ESI). The stepwise gradual evolution of HDX of multiply charged protein ions was monitored using the pulsed HDX mass spectrometry technique. Upon introducing a very short pulse of D2O (in the μs to ms time scale) into the linear ion trap (LIT) of a time-of-flight (TOF) mass spectrometer, bimodal distributions were detected for the ions of cytochrome c and ubiquitin. Mechanistic details of HDX reactions for ubiquitin and cytochrome c in the gas phase were uncovered and the structural transitions were followed by analyzing the kinetics of HDX.

Oligomerization interface of RAGE receptor revealed by MS-monitored hydrogen deuterium exchange.

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Ewa Sitkiewicz

Full Text Available Activation of the receptor for advanced glycation end products (RAGE leads to a chronic proinflammatory signal, affecting patients with a variety of diseases. Potentially beneficial modification of RAGE activity requires understanding the signal transduction mechanism at the molecular level. The ligand binding domain is structurally uncoupled from the cytoplasmic domain, suggesting receptor oligomerization is a requirement for receptor activation. In this study, we used hydrogen-deuterium exchange and mass spectrometry to map structural differences between the monomeric and oligomeric forms of RAGE. Our results indicated the presence of a region shielded from exchange in the oligomeric form of RAGE and led to the identification of a new oligomerization interface localized at the linker region between domains C1 and C2. Based on this finding, a model of a RAGE dimer and higher oligomeric state was constructed.

Hydrogen detector

International Nuclear Information System (INIS)

Kumagaya, Hiromichi; Yoshida, Kazuo; Sanada, Kazuo; Chigira, Sadao.

1994-01-01

The present invention concerns a hydrogen detector for detecting water-sodium reaction. The hydrogen detector comprises a sensor portion having coiled optical fibers and detects hydrogen on the basis of the increase of light transmission loss upon hydrogen absorption. In the hydrogen detector, optical fibers are wound around and welded to the outer circumference of a quartz rod, as well as the thickness of the clad layer of the optical fiber is reduced by etching. With such procedures, size of the hydrogen detecting sensor portion can be decreased easily. Further, since it can be used at high temperature, diffusion rate is improved to shorten the detection time. (N.H.)

{tau} - hydrogen phosphate of zirconia in sodium salt form and some of its properties; {tau} - hidrogenofosfato de zirconio en forma sodica y algunas de sus propiedades

Energy Technology Data Exchange (ETDEWEB)

Fernandez V, S.M.; Ordonez R, E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2004-07-01

It is reported the obtaining and characterization in the sodium salt form of the {tau}-hydrogen phosphate of zirconium in sodium form, this compound it was synthesized, for a new technique developed in the laboratory of Dept. of Chemistry of the ININ. The characterization was carried out for XRD, IR, Sem and EDS the thermal gravimetric analysis is also reported. (Author)

Operating experiences of Heavy Water Plant at Talcher using bithermal ammonia-hydrogen exchange process (Paper No. 1.9)

International Nuclear Information System (INIS)

Haldar, T.K.; Manoj Kumar; Ramamurty, C.B.

1992-01-01

A heavy water plant employing bithermal ammonia-hydrogen exchange process was set up at Talcher (India). The energy consumption in the process is lower as compared to monothermal process. The plant performance was affected by various problems and has resulted in low heavy water production. The problems are: (i)formation of solid deposits, (ii)inability of exchange towers to process design gas flow rates, (iii)inadequate exchange efficiency of the sieve trays provided as exchange trays, and (iv)differential amide concentration in different plant sections. These problems and their effect on the overall plant performance are discussed in detail and modifications to improve the performance are suggested. (author). 4 figs

Blockade of persistent sodium currents contributes to the riluzole-induced inhibition of spontaneous activity and oscillations in injured DRG neurons.

Directory of Open Access Journals (Sweden)

Rou-Gang Xie

Full Text Available In addition to a fast activating and immediately inactivating inward sodium current, many types of excitable cells possess a noninactivating or slowly inactivating component: the persistent sodium current (I(NaP. The I(NaP is found in normal primary sensory neurons where it is mediated by tetrodotoxin-sensitive sodium channels. The dorsal root ganglion (DRG is the gateway for ectopic impulses that originate in pathological pain signals from the periphery. However, the role of I(NaP in DRG neurons remains unclear, particularly in neuropathic pain states. Using in vivo recordings from single medium- and large-diameter fibers isolated from the compressed DRG in Sprague-Dawley rats, we show that local application of riluzole, which blocks the I(NaP, also inhibits the spontaneous activity of A-type DRG neurons in a dose-dependent manner. Significantly, riluzole also abolished subthreshold membrane potential oscillations (SMPOs, although DRG neurons still responded to intracellular current injection with a single full-sized spike. In addition, the I(NaP was enhanced in medium- and large-sized neurons of the compressed DRG, while bath-applied riluzole significantly inhibited the I(NaP without affecting the transient sodium current (I(NaT. Taken together, these results demonstrate for the first time that the I(NaP blocker riluzole selectively inhibits I(NaP and thereby blocks SMPOs and the ectopic spontaneous activity of injured A-type DRG neurons. This suggests that the I(NaP of DRG neurons is a potential target for treating neuropathic pain at the peripheral level.

Blockade of persistent sodium currents contributes to the riluzole-induced inhibition of spontaneous activity and oscillations in injured DRG neurons.

Science.gov (United States)

Xie, Rou-Gang; Zheng, Da-Wei; Xing, Jun-Ling; Zhang, Xu-Jie; Song, Ying; Xie, Ya-Bin; Kuang, Fang; Dong, Hui; You, Si-Wei; Xu, Hui; Hu, San-Jue

2011-04-25

In addition to a fast activating and immediately inactivating inward sodium current, many types of excitable cells possess a noninactivating or slowly inactivating component: the persistent sodium current (I(NaP)). The I(NaP) is found in normal primary sensory neurons where it is mediated by tetrodotoxin-sensitive sodium channels. The dorsal root ganglion (DRG) is the gateway for ectopic impulses that originate in pathological pain signals from the periphery. However, the role of I(NaP) in DRG neurons remains unclear, particularly in neuropathic pain states. Using in vivo recordings from single medium- and large-diameter fibers isolated from the compressed DRG in Sprague-Dawley rats, we show that local application of riluzole, which blocks the I(NaP), also inhibits the spontaneous activity of A-type DRG neurons in a dose-dependent manner. Significantly, riluzole also abolished subthreshold membrane potential oscillations (SMPOs), although DRG neurons still responded to intracellular current injection with a single full-sized spike. In addition, the I(NaP) was enhanced in medium- and large-sized neurons of the compressed DRG, while bath-applied riluzole significantly inhibited the I(NaP) without affecting the transient sodium current (I(NaT)). Taken together, these results demonstrate for the first time that the I(NaP) blocker riluzole selectively inhibits I(NaP) and thereby blocks SMPOs and the ectopic spontaneous activity of injured A-type DRG neurons. This suggests that the I(NaP) of DRG neurons is a potential target for treating neuropathic pain at the peripheral level.