WorldWideScience

Sample records for barium hydrides

  1. Hydrid Antibiotics

    Czech Academy of Sciences Publication Activity Database

    Běhal, Vladislav

    2003-01-01

    Roč. 48, č. 1 (2003), s. 17-25 ISSN 0015-5632 R&D Projects: GA ČR GA204/01/1004 Institutional research plan: CEZ:AV0Z5020903 Keywords : hydrid * antibiotics Subject RIV: EE - Microbiology, Virology Impact factor: 0.857, year: 2003

  2. Barium Sulfate

    Science.gov (United States)

    ... uses a computer to put together x-ray images to create cross-sectional or three dimensional pictures of the inside of the body). Barium sulfate is in a class of medications called radiopaque contrast media. It works by coating the esophagus, stomach, or ...

  3. Boron Hydrides

    Science.gov (United States)

    1946-07-01

    of direct interest could be b.P.4d. ’Thus the discovory of a now proj.ect, since silano is probably too readily infla-zmablo for practical usc’ this...devoted, ho specc4fie compounds vhitih a’-ould be tocdte at prescnt arc: nron tiy * silano , %;2.SiFi3 , diothyl sila~no, (C2 115 )2 Si112, mono r.-rop; ! (n...Bcrohydrido or Li h.... I .A-4A- The prepuation of Silano med of Stannane by the interaction or lithium aluzirun hydride v-ithl silicon tetrtchiorido and

  4. Barite (Barium)

    Science.gov (United States)

    Johnson, Craig A.; Piatak, Nadine M.; Miller, M. Michael; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Barite (barium sulfate, BaSO4) is vital to the oil and gas industry because it is a key constituent of the mud used to drill oil and gas wells. Elemental barium is an additive in optical glass, ceramic glazes, and other products. Within the United States, barite is produced mainly from mines in Nevada. Imports in 2011 (the latest year for which complete data were available) accounted for 78 percent of domestic consumption and came mostly from China.Barite deposits can be divided into the following four main types: bedded-sedimentary; bedded-volcanic; vein, cavity-fill, and metasomatic; and residual. Bedded-sedimentary deposits, which are found in sedimentary rocks with characteristics of high biological productivity during sediment accumulation, are the major sources of barite production and account for the majority of reserves, both in the United States and worldwide. In 2013, China and India were the leading producers of barite, and they have large identified resources that position them to be significant producers for the foreseeable future. The potential for undiscovered barite resources in the United States and in many other countries is considerable, however. The expected tight supply and rising costs in the coming years will likely be met by increased production from such countries as Kazakhstan, Mexico, Morocco, and Vietnam.Barium has limited mobility in the environment and exposed barium in the vicinity of barite mines poses minimal risk to human or ecosystem health. Of greater concern is the potential for acidic metal-bearing drainage at sites where the barite ores or waste rocks contain abundant sulfide minerals. This risk is lessened naturally if the host rocks at the site are acid-neutralizing, and the risk can also be lessened by engineering measures.

  5. BARIUM RECOVERY PROCESS

    Science.gov (United States)

    Blanco, R.E.

    1959-07-21

    A method of separating barium from nuclear fission products is described. In accordance with the invention, barium may be recovered from an acidic solution of neutron-irradiated fissionable material by carrying ihe barium cut of solution as a sulfate with lead as a carrier and then dissolving the barium-containing precipitate in an aqueous solution of an aliphatic diamine chelating reagent. The barium values together with certain other metallic values present in the diamine solution are then absorbed onto a cation exchange resin and the barium is selectively eluted from the resin bed with concentrated nitric acid.

  6. Barium enema (image)

    Science.gov (United States)

    A barium enema is performed to examine the walls of the colon. During the procedure, a well lubricated enema tube is inserted gently into the rectum. The barium, a radiopaque (shows up on X-ray) contrast ...

  7. Esophagram (Barium Swallow Study)

    Science.gov (United States)

    ... drink 1 to 2 cups of barium. The barium is a contrast material that makes liquids show up on the ... MRI Intravenous Contrast Information MRI with or without Contrast Small Bowel Follow Through (SBFT) Tailored Barium Swallow Study The Upper GI Study (GI Series) ...

  8. Tailored Barium Swallow Study

    Science.gov (United States)

    ... Different textures of food are often given. The barium is a contrast material that makes the food and liquid show ... MRI Intravenous Contrast Information MRI with or without Contrast Small Bowel Follow Through (SBFT) Tailored Barium Swallow Study The Upper GI Study (GI Series) ...

  9. Alkali metal hydride formation

    International Nuclear Information System (INIS)

    1976-01-01

    The present invention relates to a method of producing alkali metal hydrides by absorbing hydrogen gas under pressure into a mixture of lower alkyl mono amines and alkali metal alkyl amides selected from sodium and potassium amides formed from said amines. The present invention also includes purification of a mixture of the amines and amides which contain impurities, such as is used as a catalytic exchange liquid in the enrichment of deuterium, involving the formation of the alkali metal hydride

  10. Blistering and hydride embrittlement

    International Nuclear Information System (INIS)

    Louthan, M.R. Jr.

    1975-01-01

    The effects of hydrogen on the mechanical properties of metals have been categorized into several groups. Two of the groups, hydrogen blistering and hydride embrittlement, are reasonably well understood, and problems relating to their occurrence may be avoided if that understanding is used as a basis for selecting alloys for hydrogen service. Blistering and hydride embrittlement are described along with several techniques of materials selection and used to minimize their adverse effects. (U.S.)

  11. Aspiration of Barium Contrast

    OpenAIRE

    Fuentes Santos, Cristina; Steen, Bárbara

    2014-01-01

    The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical fil...

  12. Bonding of xenon hydrides

    NARCIS (Netherlands)

    Perez-Peralta, N.; Juarez, R.; Cerpa, E.; Bickelhaupt, F.M.; Merino, G.

    2009-01-01

    We have computed the structure and stability of the xenon hydrides HXeY (with Y = F, Cl, Br, I, CCH, CN, NC) using relativistic density functional theory (DFT) at ZORA-BP86/TZ2P level. All model systems HXeY studied here are bound equilibrium structures, but they are also significantly destabilized

  13. Modeling and minimization of barium sulfate scale

    Science.gov (United States)

    Alan W. Rudie; Peter W. Hart

    2006-01-01

    The majority of the barium present in the pulping process exits the digester as barium carbonate. Barium carbonate dissolves in the bleach plant when the pH drops below 7 and, if barium and sulfate concentrations are too high, begins to precipitate as barium sulfate. Barium is difficult to control because a mill cannot avoid this carbonate-to-sulfate transition using...

  14. Observed Barium Emission Rates

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  15. Aspiration of Barium Contrast

    Directory of Open Access Journals (Sweden)

    Cristina Fuentes Santos

    2014-01-01

    Full Text Available The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical file was reviewed, images were found of a barium swallow study that the patient had undergone months earlier, and we were able to observe the exact moment of the aspiration of the contrast material. The patient had been asymptomatic since the test.

  16. Electrolytic hydriding and hydride distribution in zircaloy-4

    International Nuclear Information System (INIS)

    Gomes, M.H.L.

    1974-01-01

    A study has been made of the electrolytic hydriding of zircaloy-4 in the range 20-80 0 C, for reaction times from 5 to 30 hours, and the effect of potential, pH and dissolved oxygen has been investigated. The hydriding reaction was more sensitive to time and temperature conditions than to the electrochemical variables. It has been shown that a controlled introduction of hydrides in zircaloy is feasible. Hydrides were found to be plate like shaped and distributed mainly along grain-boundaries. It has been shown that hydriding kinetics do not follow a simple law but may be described by a Johnson-Mehl empirical equation. On the basis of this equation an activation energy of 9.400 cal/mol has been determined, which is close to the activation energy for diffusion of hydrogen in the hydride. (author)

  17. Air and metal hydride battery

    Energy Technology Data Exchange (ETDEWEB)

    Lampinen, M.; Noponen, T. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Applied Thermodynamics

    1998-12-31

    The main goal of the air and metal hydride battery project was to enhance the performance and manufacturing technology of both electrodes to such a degree that an air-metal hydride battery could become a commercially and technically competitive power source for electric vehicles. By the end of the project it was possible to demonstrate the very first prototype of the air-metal hydride battery at EV scale, achieving all the required design parameters. (orig.)

  18. Hydrogen Outgassing from Lithium Hydride

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, L N; Schildbach, M A; Smith, R A; Balazs1, B; McLean II, W

    2006-04-20

    Lithium hydride is a nuclear material with a great affinity for moisture. As a result of exposure to water vapor during machining, transportation, storage and assembly, a corrosion layer (oxide and/or hydroxide) always forms on the surface of lithium hydride resulting in the release of hydrogen gas. Thermodynamically, lithium hydride, lithium oxide and lithium hydroxide are all stable. However, lithium hydroxides formed near the lithium hydride substrate (interface hydroxide) and near the sample/vacuum interface (surface hydroxide) are much less thermally stable than their bulk counterpart. In a dry environment, the interface/surface hydroxides slowly degenerate over many years/decades at room temperature into lithium oxide, releasing water vapor and ultimately hydrogen gas through reaction of the water vapor with the lithium hydride substrate. This outgassing can potentially cause metal hydriding and/or compatibility issues elsewhere in the device. In this chapter, the morphology and the chemistry of the corrosion layer grown on lithium hydride (and in some cases, its isotopic cousin, lithium deuteride) as a result of exposure to moisture are investigated. The hydrogen outgassing processes associated with the formation and subsequent degeneration of this corrosion layer are described. Experimental techniques to measure the hydrogen outgassing kinetics from lithium hydride and methods employing the measured kinetics to predict hydrogen outgassing as a function of time and temperature are presented. Finally, practical procedures to mitigate the problem of hydrogen outgassing from lithium hydride are discussed.

  19. Method for preparing porous metal hydride compacts

    Science.gov (United States)

    Ron, M.; Gruen, D.M.; Mendelsohn, M.H.; Sheft, I.

    1980-01-21

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  20. Hydrogenation using hydrides and acid

    Science.gov (United States)

    Bullock, R. Morris

    1990-10-30

    A process for the non-catalytic hydrogenation of organic compounds, which contain at least one reducible functional group, which comprises reacting the organic compound, a hydride complex, preferably a transition metal hydride complex or an organosilane, and a strong acid in a liquid phase.

  1. Metal Hydride Compression

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bowman, Robert [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smith, Barton [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Anovitz, Lawrence [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jensen, Craig [Hawaii Hydrogen Carriers LLC, Honolulu, HI (United States)

    2017-07-01

    Conventional hydrogen compressors often contribute over half of the cost of hydrogen stations, have poor reliability, and have insufficient flow rates for a mature FCEV market. Fatigue associated with their moving parts including cracking of diaphragms and failure of seal leads to failure in conventional compressors, which is exacerbated by the repeated starts and stops expected at fueling stations. Furthermore, the conventional lubrication of these compressors with oil is generally unacceptable at fueling stations due to potential fuel contamination. Metal hydride (MH) technology offers a very good alternative to both conventional (mechanical) and newly developed (electrochemical, ionic liquid pistons) methods of hydrogen compression. Advantages of MH compression include simplicity in design and operation, absence of moving parts, compactness, safety and reliability, and the possibility to utilize waste industrial heat to power the compressor. Beyond conventional H2 supplies of pipelines or tanker trucks, another attractive scenario is the on-site generating, pressuring and delivering pure H2 at pressure (≥ 875 bar) for refueling vehicles at electrolysis, wind, or solar generating production facilities in distributed locations that are too remote or widely distributed for cost effective bulk transport. MH hydrogen compression utilizes a reversible heat-driven interaction of a hydride-forming metal alloy with hydrogen gas to form the MH phase and is a promising process for hydrogen energy applications [1,2]. To deliver hydrogen continuously, each stage of the compressor must consist of multiple MH beds with synchronized hydrogenation & dehydrogenation cycles. Multistage pressurization allows achievement of greater compression ratios using reduced temperature swings compared to single stage compressors. The objectives of this project are to investigate and demonstrate on a laboratory scale a two-stage MH hydrogen (H2) gas compressor with a

  2. Lower GI Series (Barium Enema)

    Science.gov (United States)

    ... single-contrast lower GI series, which uses only barium a double-contrast or air-contrast lower GI series, which uses ... to evenly coat the large intestine with the barium. If you are having a double-contrast lower GI series, the radiologist will inject air ...

  3. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  4. Complex Hydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Slattery, Darlene; Hampton, Michael

    2003-03-10

    This report describes research into the use of complex hydrides for hydrogen storage. The synthesis of a number of alanates, (AIH4) compounds, was investigated. Both wet chemical and mechano-chemical methods were studied.

  5. Barium toxicosis in a dog.

    Science.gov (United States)

    Adam, Fiona H; Noble, Peter J M; Swift, Simon T; Higgins, Brent M; Sieniawska, Christine E

    2010-09-01

    A 2-year-old 14.9-kg (32.8-lb) neutered female Shetland Sheepdog was admitted to the University of Liverpool Small Animal Teaching Hospital for evaluation of acute collapse. At admission, the dog was tachypneic and had reduced limb reflexes and muscle tone in all limbs consistent with diffuse lower motor neuron dysfunction. The dog was severely hypokalemic (1.7 mEq/L; reference range, 3.5 to 5.8 mEq/L). Clinical status of the dog deteriorated; there was muscle twitching, flaccid paralysis, and respiratory failure, which was considered a result of respiratory muscle weakness. Ventricular arrhythmias and severe acidemia (pH, 7.18; reference range, 7.35 to 7.45) developed. Intoxication was suspected, and plasma and urine samples submitted for barium analysis had barium concentrations comparable with those reported in humans with barium toxicosis. Analysis of barium concentrations in 5 control dogs supported the diagnosis of barium toxicosis in the dog. Fluids and potassium supplementation were administered IV. The dog recovered rapidly. Electrolyte concentrations measured after recovery were consistently unremarkable. Quantification of plasma barium concentration 56 days after the presumed episode of intoxication revealed a large decrease; however, the plasma barium concentration remained elevated, compared with that in control dogs. To our knowledge, this case represented the first description of barium toxicosis in the veterinary literature. Barium toxicosis can cause life-threatening hypokalemia; however, prompt supportive treatment can yield excellent outcomes. Barium toxicosis is a rare but important differential diagnosis in animals with hypokalemia and appropriate clinical signs.

  6. On barium oxide solubility in barium-containing chloride melts

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaeva, Elena V.; Zakiryanova, Irina D.; Bovet, Andrey L.; Korzun, Iraida V. [Ural Federal Univ., Yekaterinburg (Russian Federation). Inst. of High Temperature Electrochemistry

    2016-11-01

    Oxide solubility in chloride melts depends on temperature and composition of molten solvent. The solubility of barium oxide in the solvents with barium chloride content is essentially higher than that in molten alkali chlorides. Spectral data demonstrate the existence of oxychloride ionic groupings in such melts. This work presents the results of the BaO solubility in two molten BaCl{sub 2}-NaCl systems with different barium chloride content. The received data together with earlier published results revealed the main regularities of BaO solubility in molten BaO-BaCl{sub 2}-MCl systems.

  7. Hydriding failure in water reactor fuel elements

    International Nuclear Information System (INIS)

    Sah, D.N.; Ramadasan, E.; Unnikrishnan, K.

    1980-01-01

    Hydriding of the zircaloy cladding has been one of the important causes of failure in water reactor fuel elements. This report reviews the causes, the mechanisms and the methods for prevention of hydriding failure in zircaloy clad water reactor fuel elements. The different types of hydriding of zircaloy cladding have been classified. Various factors influencing zircaloy hydriding from internal and external sources in an operating fuel element have been brought out. The findings of post-irradiation examination of fuel elements from Indian reactors, with respect to clad hydriding and features of hydriding failure are included. (author)

  8. MR Colonography with fecal tagging: Barium vs. barium ferumoxsil

    DEFF Research Database (Denmark)

    Achiam, M.P.; Chabanova, E.; Logager, V.B.

    2008-01-01

    and Methods. Twenty patients referred to CC underwent dark lumen MRC prior to the colonoscopy. Two groups of patients received two different oral contrast agents (barium sulfate and barium sulfate/ferumoxsil) as a laxative-free fecal tagging prior to the MRC. After MRC, the contrast agent was rated...... qualitatively (with the standard method using contrast-to-wall ratio) and subjectively (using a visual analog scale [VAS]) by three different blinded observers. Results. Evaluated both qualitatively and subjectively, the tagging efficiency of barium sulfate/ferumoxsil was significantly better (P ... barium sulfate alone. The VAS method for evaluating the tagging efficiency of contrast agents showed a high correlation (observer 11, r = 0.91) to the standard method using contrast-to-wall ratio and also a high interclass correlation (observer 11 and III = 0.89/0.85). MRC found I of 22 (5%) polyps

  9. Luminescent properties of aluminum hydride

    Energy Technology Data Exchange (ETDEWEB)

    Baraban, A.P.; Gabis, I.E.; Dmitriev, V.A. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Dobrotvorskii, M.A., E-mail: mstislavd@gmail.com [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Kuznetsov, V.G. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Matveeva, O.P. [National Mineral Resources University, Saint Petersburg 199106 (Russian Federation); Titov, S.A. [Petersburg State University of Railway Transport, Saint-Petersburg 190031 (Russian Federation); Voyt, A.P.; Elets, D.I. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation)

    2015-10-15

    We studied cathodoluminescence and photoluminescence of α-AlH{sub 3}– a likely candidate for use as possible hydrogen carrier in hydrogen-fueled vehicles. Luminescence properties of original α-AlH{sub 3} and α-AlH{sub 3} irradiated with ultraviolet were compared. The latter procedure leads to activation of thermal decomposition of α-AlH{sub 3} and thus has a practical implementation. We showed that the original and UV-modified aluminum hydride contain luminescence centers ‐ structural defects of the same type, presumably hydrogen vacancies, characterized by a single set of characteristic bands of radiation. The observed luminescence is the result of radiative intracenter relaxation of the luminescence center (hydrogen vacancy) excited by electrons or photons, and its intensity is defined by the concentration of vacancies, and the area of their possible excitation. UV-activation of the dehydrogenation process of aluminum hydride leads to changes in the spatial distribution of the luminescence centers. For short times of exposure their concentration increases mainly in the surface regions of the crystals. At high exposures, this process extends to the bulk of the aluminum hydride and ends with a decrease in concentration of luminescence centers in the surface region. - Highlights: • Aluminum hydride contains hydrogen vacancies which serve as luminescence centers. • The luminescence is the result of radiative relaxation of excited centers. • Hydride UV-irradiation alters distribution and concentration of luminescence centers.

  10. Statistical properties of barium stars

    International Nuclear Information System (INIS)

    Hakkila, J.E.

    1986-01-01

    Barium stars are G- and K-giant stars with atmospheric excesses of s-process elements, and a broadband spectral depression in the blue portion of the spectrum. The strength of the λ4554 Ball line is used as a classification parameter known as the Barium Intensity. They have a mean absolute magnitude of 1.0 and a dispersion of 1.2 magnitudes (assuming a Gaussian distribution in absolute magnitude) as measured from secular and statistical parallaxes. These stars apparently belong to a young-disk population from analyses of both the solar reflex motion and their residual velocity distribution, which implies that they have an upper mass limit of around three solar masses. There is no apparent correlation of barium intensity with either luminosity or kinematic properties. The barium stars appear to be preferentially distributed in the direction of the local spiral arm, but show no preference to associate with or avoid the direction of the galactic center. They do not appear related to either the carbon or S-stars because of these tendencies and because of the stellar population to which each type of star belongs. The distribution in absolute magnitude combined with star count analyses implies that these stars are slightly less numerous than previously believed. Barium stars show infrared excesses that correlate with their barium intensities

  11. Barium light source method and apparatus

    Science.gov (United States)

    Curry, John J. (Inventor); MacDonagh-Dumler, Jeffrey (Inventor); Anderson, Heidi M. (Inventor); Lawler, James E. (Inventor)

    2002-01-01

    Visible light emission is obtained from a plasma containing elemental barium including neutral barium atoms and barium ion species. Neutral barium provides a strong green light emission in the center of the visible spectrum with a highly efficient conversion of electrical energy into visible light. By the selective excitation of barium ionic species, emission of visible light at longer and shorter wavelengths can be obtained simultaneously with the green emission from neutral barium, effectively providing light that is visually perceived as white. A discharge vessel contains the elemental barium and a buffer gas fill therein, and a discharge inducer is utilized to induce a desired discharge temperature and barium vapor pressure therein to produce from the barium vapor a visible light emission. The discharge can be induced utilizing a glow discharge between electrodes in the discharge vessel as well as by inductively or capacitively coupling RF energy into the plasma within the discharge vessel.

  12. Thermomechanical properties of hafnium hydride

    International Nuclear Information System (INIS)

    Ito, Masato; Kurosaki, Ken; Muta, Hiroaki; Yamanaka, Shinsuke; Uno, Masayoshi; Konashi, Kenji

    2010-01-01

    Fine bulk samples of delta-phase Hf hydride with various hydrogen contents (C H ) ranging from 1.62 to 1.72 in the atomic ratio (H/Hf) were prepared, and their thermomechanical properties were characterized. At room temperature, the sound velocity and Vickers hardness were measured. The elastic modulus was calculated from the measured sound velocity. In the temperature range from room temperature to 673 K, the thermal expansion was measured by using a dilatometer, and the linear thermal expansion coefficient was calculated. Empirical equations describing the thermomechanical properties of Hf hydride as a function of C H were proposed. (author)

  13. Properties of nanoscale metal hydrides.

    Science.gov (United States)

    Fichtner, Maximilian

    2009-05-20

    Nanoscale hydride particles may exhibit chemical stabilities which differ from those of a macroscopic system. The stabilities are mainly influenced by a surface energy term which contains size-dependent values of the surface tension, the molar volume and an additional term which takes into account a potential reduction of the excess surface energy. Thus, the equilibrium of a nanoparticular hydride system may be shifted to the hydrogenated or to the dehydrogenated side, depending on the size and on the prefix of the surface energy term of the hydrogenated and dehydrogenated material. Additional complexity appears when solid-state reactions of complex hydrides are considered and phase segregation has to be taken into account. In such a case the reversibility of complex hydrides may be reduced if the nanoparticles are free standing on a surface. However, it may be enhanced if the system is enclosed by a nanoscale void which prevents the reaction partners on the dehydrogenated side from diffusing away from each other. Moreover, the generally enhanced diffusivity in nanocrystalline systems may lower the kinetic barriers for the material's transformation and, thus, facilitate hydrogen absorption and desorption.

  14. The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters

    Science.gov (United States)

    2016-01-04

    AFRL-AFOSR-VA-TR-2016-0075 The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters KIT BOWEN JOHNS HOPKINS UNIV BALTIMORE MD... Hydride and Boron Aluminum Hydride Clusters 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1-0324 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) KIT...of both Aluminum Hydride Cluster Anions and Boron Aluminum Hydride Cluster Anions with Oxygen: Anionic Products The anionic products of reactions

  15. 75 FR 19657 - Barium Chloride From China

    Science.gov (United States)

    2010-04-15

    ... No: 2010-8568] INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-149 (Third Review)] Barium... determination to conduct a full five-year review concerning the antidumping duty order on barium chloride from... antidumping duty order on barium chloride from China would be likely to lead to continuation or recurrence of...

  16. 75 FR 33824 - Barium Chloride From China

    Science.gov (United States)

    2010-06-15

    ... COMMISSION Barium Chloride From China Determination On the basis of the record\\1\\ developed in the subject... order on barium chloride from China would be likely to lead to continuation or recurrence of material... Barium Chloride from China: Investigation No. 731-TA-149 (Third Review). By order of the Commission...

  17. The renaissance of hydrides as energy materials

    Science.gov (United States)

    Mohtadi, Rana; Orimo, Shin-Ichi

    2017-02-01

    Materials based on hydrides have been the linchpin in the development of several practical energy storage technologies, of which the most prominent example is nickel-metal hydride batteries. Motivated by the need to meet the future's energy demand, the past decade has witnessed substantial advancements in the research and development of hydrides as media for hydrogen energy storage. More recently, new and rapidly evolving discoveries have positioned hydrides as highly promising materials for future electrochemical energy storage, such as electrolytes for mono- and divalent batteries, and anodes for lithium-ion batteries. In addition, the potential of hydrides in efficient power transmission has been recently revealed. In this Review, we highlight key advances and illustrate how the versatility of hydrides has not only yielded a meaningful past, but also ensures a very bright future.

  18. Anodematerials for Metal Hydride Batteries

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf

    1997-01-01

    This report describes the work on development of hydride forming alloys for use as electrode materials in metal hydride batteries. The work has primarily been concentrated on calcium based alloys derived from the compound CaNi5. This compound has a higher capacity compared with alloys used in today...... was developed. The parameters milling time, milling intensity, number of balls and form of the alloying metals were investigated. Based on this a final alloying technique for the subsequent preparation of electrode materials was established. The technique comprises milling for 4 hours twice possibly followed...... by annealing at 700°C for 12 hours. The alloys appeared to be nanocrystalline with an average crystallite size around 10 nm before annealing. Special steel containers was developed for the annealing of the metal powders in inert atmosphere. The use of various annealing temperatures was investigated...

  19. Hydrogen /Hydride/-air secondary battery

    Science.gov (United States)

    Sarradin, J.; Bronoel, G.; Percheron-Guegan, A.; Achard, J. C.

    1979-01-01

    The use of metal hydrides as negative electrodes in a hydrogen-air secondary battery seems promising. However, in an unpressurized cell, more stable hydrides that LaNi5H6 must be selected. Partial substitutions of nickel by aluminium or manganese increase the stability of hydrides. Combined with an air reversible electrode, a specific energy close to 100 Wh/kg can be expected.

  20. Nanostructured, complex hydride systems for hydrogen generation

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-02-01

    Full Text Available Complex hydride systems for hydrogen (H2 generation for supplying fuel cells are being reviewed. In the first group, the hydride systems that are capable of generating H2 through a mechanical dehydrogenation phenomenon at the ambient temperature are discussed. There are few quite diverse systems in this group such as lithium alanate (LiAlH4 with the following additives: nanoiron (n-Fe, lithium amide (LiNH2 (a hydride/hydride system and manganese chloride MnCl2 (a hydride/halide system. Another hydride/hydride system consists of lithium amide (LiNH2 and magnesium hydride (MgH2, and finally, there is a LiBH4-FeCl2 (hydride/halide system. These hydride systems are capable of releasing from ~4 to 7 wt.% H2 at the ambient temperature during a reasonably short duration of ball milling. The second group encompasses systems that generate H2 at slightly elevated temperature (up to 100 °C. In this group lithium alanate (LiAlH4 ball milled with the nano-Fe and nano-TiN/TiC/ZrC additives is a prominent system that can relatively quickly generate up to 7 wt.% H2 at 100 °C. The other hydride is manganese borohydride (Mn(BH42 obtained by mechano-chemical activation synthesis (MCAS. In a ball milled (2LiBH4 + MnCl2 nanocomposite, Mn(BH42 co-existing with LiCl can desorb ~4.5 wt.% H2 at 100 °C within a reasonable duration of dehydrogenation. Practical application aspects of hydride systems for H2 generation/storage are also briefly discussed.

  1. Hydrogen vibrations in nickel hydride

    International Nuclear Information System (INIS)

    Eckert, J.; Daniels, W.B.; Kitchens, T.A.; Majkrzak, C.F.; Passell, L.

    1983-01-01

    This chapter examines nickel hydride which was prepared in a BeCu high pressure cell at room temperature by applying a hydrogen gas pressure of 7kbar to pellets pressed from fine nickel powder. It explains that the rate and degree of completion of the hydride formation was first checked by neutron diffraction using deuterium gas with the result that a deuterium to metal ratio of approximately 0.75 was reached. It points out that after desorption of the deuterium, the nickel sample was charged with hydrogen for the inelastic incoherent neutron scattering measurements. The chapter notes that measurements were performed with the Be filter technique at the Brookhaven High Flux Beam Reactor, and finds that the optic modes appear as a broad band in the phonon density of states from about 70 to 110 MeV with peaks at approximately 88 and 108 MeV. It finally discusses the effect of hydride formation on the acoustic phonon density of states

  2. Obtaining zircaloy powder through hydriding

    International Nuclear Information System (INIS)

    Dupim, Ivaldete da Silva; Moreira, Joao M.L.

    2009-01-01

    Zirconium alloys are good options for the metal matrix in dispersion fuels for power reactors due to their low thermal neutron absorption cross-section, good corrosion resistance, good mechanical strength and high thermal conductivity. A necessary step for obtaining such fuels is producing Zr alloy powder for the metal matrix composite material. This article presents results from the Zircaloy-4 hydrogenation tests with the purpose to embrittle the alloy as a first step for comminuting. Several hydrogenation tests were performed and studied through thermogravimetric analysis. They included H 2 pressures of 25 and 50 kPa and temperatures ranging between from 20 to 670 deg C. X-ray diffraction analysis showed in the hydrogenated samples the predominant presence of ZrH 2 and some ZrO 2 . Some kinetics parameters for the Zircaloy-4 hydrogenation reaction were obtained: the time required to reach the equilibrium state at the dwell temperature was about 100 minutes; the hydrogenation rate during the heating process from 20 to 670 deg C was about 21 mg/h, and at constant temperature of 670 deg C, the hydride rate was about 1.15 mg/h. The hydrogenation rate is largest during the heating process and most of it occurs during this period. After hydrogenated, the samples could easily be comminuted indicating that this is a possible technology to obtain Zircaloy powder. The results show that only few minutes of hydrogenation are necessary to reach the hydride levels required for comminuting the Zircaloy. The final hydride stoichiometry was between 2.7 and 2.8 H for each Zr atom in the sample (author)

  3. Direct synthesis of catalyzed hydride compounds

    Science.gov (United States)

    Gross, Karl J.; Majzoub, Eric

    2004-09-21

    A method is disclosed for directly preparing alkali metal aluminum hydrides such as NaAlH.sub.4 and Na.sub.3 AlH.sub.6 from either the alkali metal or its hydride, and aluminum. The hydride thus prepared is doped with a small portion of a transition metal catalyst compound, such as TiCl.sub.3, TiF.sub.3, or a mixture of these materials, in order to render them reversibly hydridable. The process provides for mechanically mixing the dry reagents under an inert atmosphere followed by charging the mixed materials with high pressure hydrogen while heating the mixture to about 125.degree. C. The method is relatively simple and inexpensive and provides reversible hydride compounds which are free of the usual contamination introduced by prior art wet chemical methods.

  4. Barium aspiration and alveolarisation of barium in an infant: A case report and review of management

    Directory of Open Access Journals (Sweden)

    Alan F. Isles

    2014-05-01

    Full Text Available We describe a case of bilateral inhalation and alveolarisation of barium in an infant following a barium swallow for investigation of dusky spells associated with feeds. A bronchoscopy subsequently revealed the presence of a mid-tracheal tracheo-oesophageal cleft. We review the literature on barium aspiration, its consequences and make recommendations for management.

  5. Activated aluminum hydride hydrogen storage compositions and uses thereof

    Science.gov (United States)

    Sandrock, Gary; Reilly, James; Graetz, Jason; Wegrzyn, James E.

    2010-11-23

    In one aspect, the invention relates to activated aluminum hydride hydrogen storage compositions containing aluminum hydride in the presence of, or absence of, hydrogen desorption stimulants. The invention particularly relates to such compositions having one or more hydrogen desorption stimulants selected from metal hydrides and metal aluminum hydrides. In another aspect, the invention relates to methods for generating hydrogen from such hydrogen storage compositions.

  6. Regeneration of lithium aluminum hydride.

    Science.gov (United States)

    Graetz, Jason; Wegrzyn, James; Reilly, James J

    2008-12-31

    Lithium aluminum hydride (LiAlH(4)) is a promising compound for hydrogen storage, with a high gravimetric and volumetric hydrogen density and a low decomposition temperature. Similar to other metastable hydrides, LiAlH(4) does not form by direct hydrogenation at reasonable hydrogen pressures; therefore, there is considerable interest in developing new routes to regenerate the material from the dehydrogenated products LiH and Al. Here we demonstrate a low-energy route to regenerate LiAlH(4) from LiH and Ti-catalyzed Al. The initial hydrogenation occurs in a tetrahydrofuran slurry and forms the adduct LiAlH(4).4THF. The thermodynamics of this reversible reaction were investigated by measuring pressure-composition isotherms, and the free energy was found to be small and slightly negative (DeltaG = -1.1 kJ/mol H(2)), suggesting an equilibrium hydrogen pressure of just under 1 bar at 300 K. We also demonstrate that the adduct LiAlH(4).4THF can be desolvated at low temperature to yield crystalline LiAlH(4).

  7. Hydrogen-storing hydride complexes

    Science.gov (United States)

    Srinivasan, Sesha S [Tampa, FL; Niemann, Michael U [Venice, FL; Goswami, D Yogi [Tampa, FL; Stefanakos, Elias K [Tampa, FL

    2012-04-10

    A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

  8. Metal Hydrides for Rechargeable Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Valoeen, Lars Ole

    2000-03-01

    Rechargeable battery systems are paramount in the power supply of modern electronic and electromechanical equipment. For the time being, the most promising secondary battery systems for the future are the lithium-ion and the nickel metal hydride (NiMH) batteries. In this thesis, metal hydrides and their properties are described with the aim of characterizing and improving those. The thesis has a special focus on the AB{sub 5} type hydrogen storage alloys, where A is a rare earth metal like lanthanum, or more commonly misch metal, which is a mixture of rare earth metals, mainly lanthanum, cerium, neodymium and praseodymium. B is a transition metal, mainly nickel, commonly with additions of aluminium, cobalt, and manganese. The misch metal composition was found to be very important for the geometry of the unit cell in AB{sub 5} type alloys, and consequently the equilibrium pressure of hydrogen in these types of alloys. The A site substitution of lanthanum by misch metal did not decrease the surface catalytic properties of AB{sub 5} type alloys. B-site substitution of nickel with other transition elements, however, substantially reduced the catalytic activity of the alloy. If the internal pressure within the electrochemical test cell was increased using inert argon gas, a considerable increase in the high rate charge/discharge performance of LaNi{sub 5} was observed. An increased internal pressure would enable the utilisation of alloys with a high hydrogen equivalent pressure in batteries. Such alloys often have favourable kinetics and high hydrogen diffusion rates and thus have a potential for improving the high current discharge rates in metal hydride batteries. The kinetic properties of metal hydride electrodes were found to improve throughout their lifetime. The activation properties were found highly dependent on the charge/discharge current. Fewer charge/discharge cycles were needed to activate the electrodes if a small current was used instead of a higher

  9. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  10. Hydride observations using the neutrography technique

    International Nuclear Information System (INIS)

    Meyer, G.; Baruj, A.; Borzone, E.M.; Cardenas, R.; Szames, E.; Somoza, J.; Rivas, S.; Sanchez, F.A.; Marin, J.

    2012-01-01

    Neutron radiography observations were performed at the RA-6 experimental nuclear facility in Bariloche. Images from a prototype of a hydride-based hydrogen storage device have been obtained. The technique allows visualizing the inner hydride space distribution. The hydride appeared compacted at the lower part of the prototype after several cycles of hydrogen charge and discharge. The technique has also been applied to the study of Zr/ZrH 2 samples. There is a linear relation between the sample width/hydrogen concentration and the photograph grey scale. This information could be useful for the study of nuclear engineering materials and to determine their possible degradation by hydrogen pick up (author)

  11. Laser cooling and trapping of barium

    NARCIS (Netherlands)

    De, Subhadeep

    2008-01-01

    Laser cooling and trapping of heavy alkaline-earth element barium have been demonstrated for the first time ever. For any possible cycling transition in barium that could provide strong cooling forces, the excited state has a very large branching probability to metastable states. Additional lasers

  12. Tritium removal using vanadium hydride

    International Nuclear Information System (INIS)

    Hill, F.B.; Wong, Y.W.; Chan, Y.N.

    1978-01-01

    The results of an initial examination of the feasibility of separation of tritium from gaseous protium-tritium mixtures using vanadium hydride in cyclic processes is reported. Interest was drawn to the vanadium-hydrogen system because of the so-called inverse isotope effect exhibited by this system. Thus the tritide is more stable than the protide, a fact which makes the system attractive for removal of tritium from a mixture in which the light isotope predominates. The initial results of three phases of the research program are reported, dealing with studies of the equilibrium and kinetics properties of isotope exchange, development of an equilibrium theory of isotope separation via heatless adsorption, and experiments on the performance of a single heatless adsorption stage. In the equilibrium and kinetics studies, measurements were made of pressure-composition isotherms, the HT--H 2 separation factors and rates of HT--H 2 exchange. This information was used to evaluate constants in the theory and to understand the performance of the heatless adsorption experiments. A recently developed equilibrium theory of heatless adsorption was applied to the HT--H 2 separation using vanadium hydride. Using the theory it was predicted that no separation would occur by pressure cycling wholly within the β phase but that separation would occur by cycling between the β and γ phases and using high purge-to-feed ratios. Heatless adsorption experiments conducted within the β phase led to inverse separations rather than no separation. A kinetic isotope effect may be responsible. Cycling between the β and γ phases led to separation but not to the predicted complete removal of HT from the product stream, possibly because of finite rates of exchange. Further experimental and theoretical work is suggested which may ultimately make possible assessment of the feasibility and practicability of hydrogen isotope separation by this approach

  13. Disposal of tritium-exposed metal hydrides

    International Nuclear Information System (INIS)

    Nobile, A.; Motyka, T.

    1991-01-01

    A plan has been established for disposal of tritium-exposed metal hydrides used in Savannah River Site (SRS) tritium production or Materials Test Facility (MTF) R ampersand D operations. The recommended plan assumes that the first tritium-exposed metal hydrides will be disposed of after startup of the Solid Waste Disposal Facility (SWDF) Expansion Project in 1992, and thus the plan is consistent with the new disposal requiremkents that will be in effect for the SWDF Expansion Project. Process beds containing tritium-exposed metal hydride powder will be disposed of without removal of the powder from the bed; however, disposal of tritium-exposed metal hydride powder that has been removed from its process vessel is also addressed

  14. Method of making alkali metal hydrides

    Science.gov (United States)

    Pecharsky, Vitalij K.; Gupta, Shalabh; Pruski, Marek; Hlova, Ihor; Castle, Andra

    2017-05-30

    A method is provided for making alkali metal hydrides by mechanochemically reacting alkali metal and hydrogen gas under mild temperature (e.g room temperature) and hydrogen pressure conditions without the need for catalyst, solvent, and intentional heating or cooling.

  15. Influence of hydrides orientation on strain, damage and failure of hydrided zircaloy-4

    International Nuclear Information System (INIS)

    Racine, A.

    2005-09-01

    In pressurized water reactors of nuclear power plants, fuel pellets are contained in cladding tubes, made of Zirconium alloy, for instance Zircaloy-4. During their life in the primary water of the reactor (155 bars, 300 C), cladding tubes are oxidized and consequently hydrided. A part of the hydrogen given off precipitates as Zirconium hydrides in the bulk material and embrittles the material. This embrittlement depends on many parameters, among which hydrogen content and orientation of hydrides with respect to the applied stress. This investigation is devoted to the influence of the orientation of hydrides with respect to the applied stress on strain, damage and failure mechanisms. Macroscopic and SEM in-situ ring tensile tests are performed on cladding tube material (unirradiated cold worked stress-relieved Zircaloy-4) hydrided with about 200 and 500 wppm hydrogen, and with different main hydrides orientation: either parallel or perpendicular to the circumferential tensile direction. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. Neither the tensile stress-strain response nor the global and local strain modes are significantly affected by hydrogen content or hydride orientation, but the failure modes are strongly modified. Indeed, only 200 wppm radial hydrides embrittle Zy-4: sample fail in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases sample reach at least 750 MPa before necking and final failure, in ductile or brittle mode. To model this particular heterogeneous material behavior, a non-coupled damage approach which takes into account the anisotropic distribution of the hydrides is proposed. Its parameters are identified from the macroscopic strain field measurements and a

  16. A new double contrast barium enema

    International Nuclear Information System (INIS)

    Park, Jun Sang; Cho, Won Sik; Lee, Sung Woo; Lee, Mun Gyu; Jeon, Jeong Dong; Jaun, Woo Ki; Han, Chung Yul

    1987-01-01

    A new technic of the barium enema was proposed for the better colonic double contrast study with the average 204ml of 50w/v% barium, applied to 109 serial patients. The barium was introduced to sigmoid colon, and then pushed to a mid transverse colon by the air insufflation through an enema syringe, a new device. An advance to cecum is accomplished by the air insufflation and/or the position change of the patient. The barium transfer method was developed for the best spot film exposure, through colon, by the position change of the patient, the tilting of the x-ray table and the air insufflation with the enema syringe. The mean angle of the x-ray table tilted was -10 .deg. at the beginning the barium enema till the barium sent past the splenic flexure, -15 . deg. for the best lateral view of rectum and -18 .deg. for the bet prone PA view of rectosigmoid colon. This was a simple, better and economic double contrast barium enema for the cooperative patients

  17. gamma-Zr-Hydride Precipitate in Irradiated Massive delta- Zr-Hydride

    DEFF Research Database (Denmark)

    Warren, M. R.; Bhattacharya, D. K.

    1975-01-01

    During examination of A Zircaloy-2-clad fuel pin, which had been part of a test fuel assembly in a boiling water reactor, several regions of severe internal hydriding were noticed in the upper-plenum end of the pin. Examination of similar fuel pins has shown that hydride of this type is caused by...... to irradiation-induced swelling....

  18. The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components Delayed Hydride Cracking

    CERN Document Server

    Puls, Manfred P

    2012-01-01

    By drawing together the current theoretical and experimental understanding of the phenomena of delayed hydride cracking (DHC) in zirconium alloys, The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking provides a detailed explanation focusing on the properties of hydrogen and hydrides in these alloys. Whilst the focus lies on zirconium alloys, the combination of both the empirical and mechanistic approaches creates a solid understanding that can also be applied to other hydride forming metals.   This up-to-date reference focuses on documented research surrounding DHC, including current methodologies for design and assessment of the results of periodic in-service inspections of pressure tubes in nuclear reactors. Emphasis is placed on showing that our understanding of DHC is supported by progress across a broad range of fields. These include hysteresis associated with first-order phase transformations; phase relationships in coherent crystalline metallic...

  19. Double contrast barium meal and acetylcysteine

    International Nuclear Information System (INIS)

    Kinnunen, J.; Pietilae, J.; Ahovuo, J.; Mankinen, P.; Tervahartiala, P.

    1989-01-01

    In a prospective double blind study, acetylcysteine, a local and systemic respiratory tract mucolytic agent, or a placebo, were given to 100 patients prior to a double contrast barium meal to decrease the gastric mucus viscosity and to make the mucus layer thinner, in order to permit barium to outline the furrows surrounding the areae gastricae instead of the overlying thick mucus. However, acetylcysteine failed to improve either visualization of the areae gastricae or the general quality of the double contrast barium meal. (orig.)

  20. Preliminary development of flaw evaluation procedures for delayed hydride cracking initiation under hydride non-ratcheting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, S.; Cui, J.; Kawa, D.; Shek, G.K.; Scarth, D.A. [Kinectrics Inc., Toronto, Ontario (Canada)

    2006-07-01

    The flaw evaluation procedure for Delayed Hydride Cracking (DHC) initiation currently provided in the CSA Standard N285.8 was developed for hydride ratcheting conditions, in which flaw-tip hydrides do not completely dissolve at peak temperature. Test results have shown that hydrided regions formed under non-ratcheting conditions, in which flaw-tip hydrides completely dissolve at peak temperature, have significantly higher resistance to cracking than those formed under ratcheting conditions. This paper presents some preliminary work on the development of a procedure for the evaluation of DHC initiation for flaws under hydride non-ratcheting conditions. (author)

  1. Time requirement for barium reduction in intussusception

    International Nuclear Information System (INIS)

    Hwang, Hye Eun; Kim, Seung Ho; Kang, In Young; Park, Byoung Lan; Kim, Byoung Geun

    1988-01-01

    During the period between January 1985 and December 1987, barium reduction was performed in 146 cases of intussusception who were admitted to Kwangju Christian Hospital. The results were as follows: 1. Success rate to the symptom duration is relatively constant. 2. The success rate in infants with severe dehydration was 50% but it was gradually increased in infants with moderate dehydration and in infants with mild dehydration, 83.3% and 100% respectively. 3. The success rate of 12 cases in severely dehydrated infants with positive dissection sign was 16.7%. 4. The success rate of 15 cases in moderately dehydrated infants with positive dissection sign was 66.7%. 5. The average time requirement for barium reduction was 58.3 minutes. No serious complications were noted during barium reduction, except mild vomiting. 6. With above results, it is desirable that barium reduction should be performed according to the patient's physical status and radiologic findings.

  2. Barium Isotopes in Single Presolar Grains

    Science.gov (United States)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  3. Barium appendicitis after upper gastrointestinal imaging.

    Science.gov (United States)

    Novotny, Nathan M; Lillemoe, Keith D; Falimirski, Mark E

    2010-02-01

    Barium appendicitis (BA) is a rarely seen entity with fewer than 30 reports in the literature. However, it is a known complication of barium imaging. To report a case of BA in a patient whose computed tomography (CT) scan was initially read as foreign body ingestion. An 18-year-old man presented with right lower quadrant pain after upper gastrointestinal imaging 2 weeks prior. A CT scan was obtained of his abdomen and pelvis that revealed a finding that was interpreted as a foreign body at the area of the terminal ileum. A plain X-ray study of the abdomen revealed radiopaque appendicoliths. Pathology confirmed the diagnosis of barium appendicitis. BA is a rare entity and the pathogenesis is unclear. Shorter intervals between barium study and presentation with appendicitis usually correlate with fewer complications. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  4. Synthesis of Nano-Light Magnesium Hydride for Hydrogen Storage ...

    African Journals Online (AJOL)

    Abstract. Nano-light magnesium hydride that has the capability for hydrogen storage was synthesized from treatment of magnesium ribbon with hydrogen peroxide. The optimum time for complete hydrogenation of the magnesium hydride was 5 hours.

  5. Experimental investigation of strain, damage and failure of hydrided zircaloy-4 with various hydride orientations

    International Nuclear Information System (INIS)

    Racine, A; Catherine, C.S.; Cappelaere, C.; Bornert, M.; Caldemaison, D.

    2005-01-01

    This experimental investigation is devoted to the influence of the orientation of hydrides on the mechanical response of Zircaloy-4. Ring tensile tests are performed on unirradiated CWSR Zircaloy-4, charged with about 200 or 500wppm hydrogen. Hydrides are oriented either parallel ('tangential'), or perpendicular ('radial') to the circumferential tensile direction. Tangential hydrides are usually observed in cladding tubes, however, hydrides can be reoriented after cooling under stress to become radial and then trigger brittle behavior. In this investigation, we perform, 'macroscopic' or SEM in-situ tensile tests on smooth rings, at room temperature. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. The results lead to the following conclusions: neither the tensile stress-strain response nor the strain modes are affected by hydrogen content or hydride orientation, but the failure modes are. Indeed, only 200wppm radial hydrides embrittle Zy-4: sample fails in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases samples reach at least 750 MPa before failure, with ductile or brittle mode. (authors)

  6. An experimental study on barium peritonitis in rats

    International Nuclear Information System (INIS)

    Kang, Heung Sik; Han, Man Chung; Kim, Chu Wan

    1985-01-01

    Barium sulfate is universally used contrast media in gastrointestinal roentgenology, and spillage of barium into peritoneal cavity can occur. The references on effect of barium sulfate in the peritoneal cavity have been scattered and the results are varied. In 80 rats, body weight of 130 gm to 150 gm, sterile pure barium, sterile commercial barium, intestinal content, and mixed pure barium and intestinal content were experimentally injected into the peritoneal cavity. Consecutive weekly laparotomy and microscopic examination were done for 4 weeks. The results are as followings: 1. Mind inflammatory reaction and mild adhesion after sterile pure barium injection. 2. Mild inflammatory reaction and moderate adhesion after sterile commercial barium injection. 3. Acute peritonitis and abscess formation after intestinal content injection. 4. High mortality due to severe acute peritonitis, and severe adhesion in survivors after injection of both pure barium and intestinal content.

  7. Bacterial Reduction Of Barium Sulphate By Sulphate-Reducing Bacteria

    Directory of Open Access Journals (Sweden)

    Luptáková Alena

    2015-12-01

    Full Text Available Acid mine drainage (AMD is a worldwide problem leading to contamination of water sources. AMD are characterized by low pH and high content of heavy metals and sulphates. The barium salts application presents one of the methods for the sulphates removing from AMD. Barium chloride, barium hydroxide and barium sulphide are used for the sulphates precipitation in the form of barium sulphate. Because of high investment costs of barium salts, barium sulphide is recycled from barium sulphate precipitates. It can be recycled by thermic or bacterial reduction of barium sulphate. The aim of our study was to verify experimentally the possibility of the bacterial transformation of BaSO4 to BaS by sulphate-reducing bacteria. Applied BaSO4 came from experiments of sulphates removal from Smolnik AMD using BaCl2.

  8. Hydriding and dehydriding rates and hydrogen-storage capacity of ...

    Indian Academy of Sciences (India)

    Fe2O3 (expected to increase hydriding rate) was selected as an oxide to be added. Ti was also selected since, it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. A sample, Mg–14Ni–3Fe2O3–3Ti, was prepared by reactive mechanical grinding and its hydrogen storage properties were ...

  9. Sulphate removal from sodium sulphate-rich brine and recovery of barium as a barium salt mixture.

    Science.gov (United States)

    Vadapalli, Viswanath R K; Zvimba, John N; Mulopo, Jean; Motaung, Solly

    2013-01-01

    Sulphate removal from sodium sulphate-rich brine using barium hydroxide and recovery of the barium salts has been investigated. The sodium sulphate-rich brine treated with different dosages of barium hydroxide to precipitate barium sulphate showed sulphate removal from 13.5 g/L to less than 400 mg/L over 60 min using a barium to sulphate molar ratio of 1.1. The thermal conversion of precipitated barium sulphate to barium sulphide achieved a conversion yield of 85% using coal as both a reducing agent and an energy source. The recovery of a pure mixture of barium salts from barium sulphide, which involved dissolution of barium sulphide and reaction with ammonium hydroxide resulted in recovery of a mixture of barium carbonate (62%) and barium hydroxide (38%), which is a critical input raw material for barium salts based acid mine drainage (AMD) desalination technologies. Under alkaline conditions of this barium salt mixture recovery process, ammonia gas is given off, while hydrogen sulfide is retained in solution as bisulfide species, and this provides basis for ammonium hydroxide separation and recovery for reuse, with hydrogen sulfide also recoverable for further industrial applications such as sulfur production by subsequent stripping.

  10. Aluminum Hydride Catalyzed Hydroboration of Alkynes.

    Science.gov (United States)

    Bismuto, Alessandro; Thomas, Stephen P; Cowley, Michael J

    2016-12-05

    An aluminum-catalyzed hydroboration of alkynes using either the commercially available aluminum hydride DIBAL-H or bench-stable Et 3 Al⋅DABCO as the catalyst and H-Bpin as both the boron reagent and stoichiometric hydride source has been developed. Mechanistic studies revealed a unique mode of reactivity in which the reaction is proposed to proceed through hydroalumination and σ-bond metathesis between the resultant alkenyl aluminum species and HBpin, which acts to drive turnover of the catalytic cycle. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Stress induced reorientation of vanadium hydride

    International Nuclear Information System (INIS)

    Beardsley, M.B.

    1977-10-01

    The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180 0 to 280 0 K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch

  12. Hydrogen adsorption on palladium and palladium hydride at 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Skulason, Egill; Nielsen, Gunver

    2010-01-01

    The dissociative sticking probability for H-2 on Pd films supported on sputtered Highly Ordered Pyrolytic Graphite (HOPG) has been derived from measurements of the rate of the H-D exchange reaction at 1 bar. The sticking probability for H-2, S. is higher on Pd hydride than on Pd (a factor of 1...... strongly to Pd hydride than to Pd. The activation barrier for desorption at a H coverage of one mono layer is slightly lower on Pd hydride, whereas the activation energy for adsorption is similar on Pd and Pd hydride. It is concluded that the higher sticking probability on Pd hydride is most likely caused...

  13. Barium nucleosynthesis in the disk

    Energy Technology Data Exchange (ETDEWEB)

    Twarog, B.A.

    1981-11-15

    The history of Ba production in the disk is discussed, particularly with regard to the apparent constancy of the production rate of Ba relative to Fe over the lifetime of the disk. An infall model of the chemical evolution of Ba/Fe within the disk is constructed under the assumption that the mass function and star formation rate are independent of time and Ba is produced as purely a secondary element. The model not only satisfies the present constraints for the disk, but produces a (Ba/H)-(Fe/H) relation which is consistent with the available observational data. It is shown that the apparent constancy of the Ba/Fe ratio is an artifact of (1) an inadequate and insufficiently accurated data sample, and (2) secondary production of Ba within the disk which is 20 to 80 times less efficient relative to Fe than the production ratio for the halo. The model predicts that stars formed during the transition period between halo and disk should show a Ba/Fe excess relative to the Sun of about a factor of 2. It is concluded that the possible sources of the Ba/Fe overproduction in the halo relative to the disk are incompatible with present theoretical limits on the mass ranges for iron and barium production by stars.

  14. Warming barium sulfate improves esophageal leak detection in pig model.

    Science.gov (United States)

    Raman, Vignesh; MacGlaflin, Caitlyn E; Moodie, Karen L; Kaiser, Larry R; Erkmen, Cherie P

    2015-12-01

    Barium esophagograms have poor sensitivity in detecting leaks. We hypothesized that heating barium would decrease viscosity, facilitate extravasation, and enhance its sensitivity in detecting esophageal leaks. We characterized the viscosity of barium at increasing temperatures. We measured the radiopacity of barium at 25°C and 50°C. We determined the smallest diameter defect in esophagus that barium can detect by perforating a porcine esophageal segment with angiocatheters of various diameters, injecting barium at 25°C, and observing extravasation of contrast. We repeated this with barium heated to 30°C, 40°C, 50°C, and 70°C. To determine the ability of barium to detect a staple line leak, we perforated a stapled esophageal segment by air insufflation, injected barium at different temperatures, and monitored extravasation. We used Visipaque, a water-soluble contrast agent, for comparison in all experiments. The viscosity of barium decreased with increasing temperature. The radiopacity of barium did not change with increasing temperature and was higher than that of Visipaque (P detectable leak decreased from 2.1 mm with barium at 25°C to 1.3 mm at 40°C and 1.1 mm with Visipaque (P leak detection increased from 0% for barium at 25°C to 80% (P = 0.02) with barium at 40°C. There was no significant difference in sensitivity between barium at 40°C and Visipaque. Barium warmed to 40°C offers the best sensitivity of esophageal leak detection without compromising radiopacity. Barium at 40°C may be the optimum choice for swallow study to detect esophageal leaks. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Sealed metal-hydride batteries for aerospace applications

    Science.gov (United States)

    Coates, Dwaine; Wright, R. D.

    Nickel and silver-metal hydride batteries are being developed for aerospace applications by Eagle-Picher. Metal hydride batteries offer a number of advantages over other aerospace battery systems. Nickel-metal hydride batteries have twice the gravimetric energy density of nickel-cadmium batteries and twice the volumetric energy density of nickel-hydrogen batteries. Silver-metal hydride batteries have the potential of three times the energy density of nickel-metal hydride. Aerospace metal hydride batteries are hermetically sealed, operate at low pressure and are prismatic in geometry. They exhibit excellent overcharge and overdischarge capability. The objective of current programs at Eagle-Picher is to develop high energy density, long cycle life metal-hydride batteries for the aerospace market and to establish a testing database to support future applications.

  16. Effects of δ-hydride precipitation at a crack tip on crack propagation in delayed hydride cracking of Zircaloy-2

    Science.gov (United States)

    Kubo, T.; Kobayashi, Y.

    2013-08-01

    Delayed hydride cracking (DHC) of Zircaloy-2 is one possible mechanism for the failure of boiling water reactor fuel rods in ramp tests at high burnup. Analyses were made for hydrogen diffusion around a crack tip to estimate the crack velocity of DHC in zirconium alloys, placing importance on effects of precipitation of δ-hydride. The stress distribution around the crack tip is significantly altered by precipitation of hydride, which was strictly analyzed using a finite element computer code. Then, stress-driven hydrogen diffusion under the altered stress distribution was analyzed by a differential method. Overlapping of external stress and hydride precipitation at a crack tip induces two stress peaks; one at a crack tip and the other at the front end of the hydride precipitate. Since the latter is larger than the former, more hydrogen diffuses to the front end of the hydride precipitate, thereby accelerating hydride growth compared with that in the absence of the hydride. These results indicated that, after hydride was formed in front of the crack tip, it grew almost steadily accompanying the interaction of hydrogen diffusion, hydride growth and the stress alteration by hydride precipitation. Finally, crack velocity was estimated from the calculated hydrogen flux into the crack tip as a function of temperature, stress intensity factor and material strength. There was qualitatively good agreement between calculation results and experimental data. The stress distribution around the crack tip is significantly altered by precipitation of hydride. Overlapping of external stress and hydride precipitation at a crack tip induces two stress peaks; one at a crack tip and the other at the front end of the hydride precipitate. Since the latter is larger than the former, more hydrogen diffuses to the front end of the hydride precipitate, thereby accelerating hydride growth compared with that in the absence of the hydride. These results indicated that, after hydride was formed

  17. Magnesium hydrides and their phase transitions

    Czech Academy of Sciences Publication Activity Database

    Paidar, Václav

    2016-01-01

    Roč. 41, č. 23 (2016), s. 9769-9773 ISSN 0360-3199 R&D Projects: GA MŠk(CZ) LD13069 Institutional support: RVO:68378271 Keywords : hydrogen * magnesium and transition metal hydrides * crystal structure stability * displacive phase transformations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.582, year: 2016

  18. Are RENiAl hydrides metallic?

    Czech Academy of Sciences Publication Activity Database

    Eichinger, K.; Havela, L.; Prokleška, J.; Stelmakhovych, O.; Daniš, S.; Šantavá, Eva; Miliyanchuk, K.

    2009-01-01

    Roč. 100, č. 9 (2009), s. 1200-1202 ISSN 1862-5282 Grant - others:GA ČR(CZ) GA202/07/0418 Institutional research plan: CEZ:AV0Z10100520 Keywords : rare earth metals * magnetism * hydrides Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.862, year: 2009

  19. Barium ferrite nanoparticles prepared by self-propagating low ...

    Indian Academy of Sciences (India)

    Administrator

    temperature combustion method using ... talline barium ferrite. Keywords. Barium ferrite; self-propagating combustion method; magnetic property; X-ray diffraction; morphology. 1. Introduction .... known that γ-Fe2O3 is a cubic spinel, whose chemical.

  20. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium calcium...

  1. Synthesis of nanosized barium titanate/epoxy resin composites and ...

    Indian Academy of Sciences (India)

    Barium titanate/epoxy resin composites have been synthesized and tested for microwave absorption/ transmission. Nanocrystalline barium titanate (BaTiO3 or BT) ... Anechoic chamber; barium titanate; electromagnetic interference and compatibility; epoxy resin ..... electromagnetic waves, the two port calibrations have been.

  2. Effect of sodium bicarbonate pretreatment on barium coating of mucosa during double contrast barium meal

    International Nuclear Information System (INIS)

    Kinnunen, J.; Toetterman, S.; Kaila, R.; Pietilae, J.; Linden, H.; Tervahartiala, P.

    1983-01-01

    The radiographic pattern of the areae gastricae is produced by barium lying in the intersecting furrows of the gastric mucosal surface. However, if the mucus layer on the gastric mucosa is thick, it interferes with the barium coating of the areae gastricae during double contrast barium meal. As sodium bicarbonate decreases the viscosity of mucus and thus may make the gastric mucus layer thinner, it was evaluated as a pretreatment agent in a routine double contrast upper-gastrointestinal study to improve the visualization of the areae gastricae. In a single blind study, 53 of 106 patients took sodium bicarbonate water mixtures at bedtime the day before and on the morning of the examination. According to the results of the present study mucolysis induced by the used doses of sodium bicarbonate does not significantly affect micromucosal visualization during double-contrast barium meal. (orig.) [de

  3. Hydrogen storage in metallic hydrides: the hydrides of magnesium-nickel alloys

    International Nuclear Information System (INIS)

    Silva, E.P. da.

    1981-01-01

    The massive and common use of hydrogen as an energy carrier requires an adequate solution to the problem of storing it. High pressure or low temperatures are not entirely satisfactory, having each a limited range of applications. Reversible metal hydrides cover a range of applications intermediate to high pressure gas and low temperature liquid hydrogen, retaining very favorable safety and energy density characteristics, both for mobile and stationary applications. This work demonstrates the technical viability of storing hydrogen in metal hydrides of magnesium-nickel alloys. Also, it shows that technology, a product of science, can be generated within an academic environment, of the goal is clear, the demand outstanding and the means available. We review briefly theoretical models relating to metal hydride properties, specially the thermodynamics properties relevant to this work. We report our experimental results on hydrides of magnesium-nickel alloys of various compositions including data on structure, hydrogen storage capacities, reaction kinetics, pressure-composition isotherms. We selected a promising alloy for mass production, built and tested a modular storage tank based on the hydrides of the alloy, with a capacity for storing 10 Nm sup(3) of hydrogen of 1 atm and 20 sup(0)C. The tank weighs 46,3 Kg and has a volume of 21 l. (author)

  4. Work Function Calculation For Hafnium- Barium System

    Directory of Open Access Journals (Sweden)

    K.A. Tursunmetov

    2015-08-01

    Full Text Available The adsorption process of barium atoms on hafnium is considered. A structural model of the system is presented and on the basis of calculation of interaction between ions dipole system the dependence of the work function on the coating.

  5. High temperature impedance spectroscopy of barium stannate ...

    Indian Academy of Sciences (India)

    High temperature impedance spectroscopy of barium stannate, BaSnO3. SHAIL UPADHYAY. Department of Physics, Institute of Technology, Banaras Hindu University, Varanasi 221 005, India. MS received 29 May 2012; revised 14 July 2012. Abstract. Polycrystalline powder of BaSnO3 was prepared at 1300 ◦C using a ...

  6. Impurities in barium titanate posistor ceramics

    Czech Academy of Sciences Publication Activity Database

    Korniyenko, S. M.; Bykov, I. P.; Glinchuk, M. J.; Laguta, V. V.; Belous, A. G.; Jastrabík, Lubomír

    2000-01-01

    Roč. 239, - (2000), s. 1209-1218 ISSN 0015-0193 Institutional research plan: CEZ:AV0Z1010914 Keywords : barium titanate phase transition * ESR * positive temperature coefficient of resistivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.547, year: 2000

  7. Magneto-optical trapping of barium

    NARCIS (Netherlands)

    De, S.; Dammalapati, U.; Jungmann, K.; Willmann, L.

    Laser cooling and trapping of the heavy alkaline-earth-metal element barium has been achieved based on the strong 6s(2) (1)S(0)-6s6p (1)P(1) transition. The excited state decays to a large fraction into metastable D states. Two schemes were implemented where three additional laser-driven transitions

  8. Scattering lengths of calcium and barium isotopes

    NARCIS (Netherlands)

    Dammalapati, U.; Willmann, L.; Knoop, S.

    2011-01-01

    We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca

  9. 75 FR 20625 - Barium Chloride From China

    Science.gov (United States)

    2010-04-20

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Revised schedule for the subject review. DATES: Effective Date: April 9, 2010. FOR FURTHER INFORMATION CONTACT: Amy...

  10. Barium Transport Process in Impregnated Dispenser Cathodes.

    Science.gov (United States)

    1982-01-25

    Coupon Indicating Initial Discontinuity in Bariumn Coverage 17 ...... .... aru apo Hae Cuo ......... GsLie ifuso ..4... Fig. 5. SAI! Barium ’tap of a...monitoring. Electronics Research Laboratory: Microelectronics. GaAs low-noise and pover devices, semiconductor lasers. electromagnetic and optical propagation...phenomena, quantum electronics, laser comunications, lidar, and electro-optics; communication sciences, applied electronics, semiconductor crystal

  11. Electrical characterization of zirconium substituted barium titanate ...

    Indian Academy of Sciences (India)

    Nyquist (Cole–Cole) plots show both inter and intra grain boundary ... Ferroelectrics; barium zirconate titanate; complex impedance spectroscopy. ... The impedance plots in the complex plane appear in the form of succe- ssion of semicircles representing electrical phenomena due to the bulk material, grain boundary effect ...

  12. Hydridation of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Domizzi, G; Luppo, M.I; Ortiz, M; Vigna, G

    2004-01-01

    The production of Ti pieces or their alloys through powder metallurgy is an economical alternative that replaces the costly methods commonly used. The Ti-6AI-4V alloy is widely used in the aerospace, chemical and medical industries. The use of powder from the alloy instead of using more pure alloyed titanium powders, further simplifies the production process. The presence of V allows the phase β to stabilize at very low temperatures and both alloys alter the Ti-H equilibrium diagram. This work analyzes to what degree these effects influence the obtaining of powders from this alloy from that of hydridation and dehydridation. Although it has slower kinetics, powders can be produced in times similar to those found for grade 2 Ti since the distribution of hydrides in the sample is uniform and the material is fragile enough for concentrations of approximately 0.7 H/Ti (CW)

  13. Nickel metal hydride LEO cycle testing

    Science.gov (United States)

    Lowery, Eric

    1995-01-01

    The George C. Marshall Space Flight Center is working to characterize aerospace AB5 Nickel Metal Hydride (NiMH) cells. The cells are being evaluated in terms of storage, low earth orbit (LEO) cycling, and response to parametric testing (high rate charge and discharge, charge retention, pulse current ability, etc.). Cells manufactured by Eagle Picher are the subjects of the evaluation. There is speculation that NiMH cells may become direct replacements for current Nickel Cadmium cells in the near future.

  14. HYDRIDE-RELATED DEGRADATION OF SNF CLADDING UNDER REPOSITORY CONDITIONS

    International Nuclear Information System (INIS)

    McCoy, K.

    2000-01-01

    The purpose and scope of this analysis/model report is to analyze the degradation of commercial spent nuclear fuel (CSNF) cladding under repository conditions by the hydride-related metallurgical processes, such as delayed hydride cracking (DHC), hydride reorientation and hydrogen embrittlement, thereby providing a better understanding of the degradation process and clarifying which aspects of the process are known and which need further evaluation and investigation. The intended use is as an input to a more general analysis of cladding degradation

  15. Aluminum Hydride as a Fuel Supplement to NanoThermites

    Science.gov (United States)

    2014-01-01

    SECURITY CLASSIFICATION OF: An experimental study was conducted in which aluminum hydride (alane, AlH3) replaced nanoaluminum incrementally as a fuel in a...pressurization rate, and burning velocity when micron-scale aluminum hydride was used as a minor fuel component in a nanoaluminum–copper-oxide thermite...mixture. Peak pressurization rates were found when the aluminum hydride made up about 25% of the fuel by mole. Pressurization rates increase by a

  16. Growth and decomposition of Lithium and Lithium hydride on Nickel

    DEFF Research Database (Denmark)

    Engbæk, Jakob; Nielsen, Gunver; Nielsen, Jane Hvolbæk

    2006-01-01

    In this paper we have investigated the deposition, structure and decomposition of lithium and lithium-hydride films on a nickel substrate. Using surface sensitive techniques it was possible to quantify the deposited Li amount, and to optimize the deposition procedure for synthesizing lithium...... temperature than the decomposition of the lithium-hydride, confirming the high stability and sintering problems of lithium-hydride making the storage potential a challenge. (c) 2006 Elsevier B.V. All rights reserved....

  17. Identification of the zirconium hydrides metallography in zircaloy-2

    International Nuclear Information System (INIS)

    Garcia Gonzalez, F.

    1968-01-01

    Technique for the Identification of the zirconium hydrides in metallographic specimens have been developed. Microhardness, quantitative estimation and relative orientation of the present hydrides as well as grain size determination of the different Zircaloy-2 tube specimens have also been made. The specimens used were corrosion- tested in water during various periods of time at 300 degree castrating, prior to the metallographic examination. Reference specimens, as received, and heavily hydride specimens in a hydrogen atmosphere at 800 degree centigrees, have been used in the previous stages of the work. No difficulties have been met in this early stage of acquaintanceship with the zirconium hydrides. (Author) 5 refs

  18. Spectrophotometric determination of volautile inorganic hydrides in binary gaseous mixtures

    International Nuclear Information System (INIS)

    Rezchikov, V.G.; Skachkova, I.N.; Kuznetsova, T.S.; Khrushcheva, V.V.

    1985-01-01

    A study was made on possibility of single and continuons analysis of binary mixtures (hydride-gas) for the content of volatile inorganic hydrides (VIH) from absorption spectra in the 185-280 nm band. Dependences of the percentage of VIH transmission on the wavelength are presented. It is shown that the maximum of their absorption depends on the element-hydrogen the bond length and binding energy. Detection limit for boron hydride was established to be n x 10 -3 % vol at 185-190 nm wavelength. Technique for spectrophotometric hydride determination in binary mixtures with hydrogen, argon, helium was developed. The technique provides the continuous control of gaseous mixture composition

  19. THE STEREOCHEMISTRY AND MECHANISM OF HYDRIDE REDUCTIONS OF CYCLOHEXENE OXIDES.

    Science.gov (United States)

    HYDRIDES, *OXIDATION REDUCTION REACTIONS), (* CYCLOHEXANOLS , SYNTHESIS (CHEMISTRY)), (*STEREOCHEMISTRY, CYCLOHEXANES), (*BOROHYDRIDES, REDUCTION...CHEMISTRY)), DIBORANES, OXYGEN HETEROCYCLIC COMPOUNDS, CYCLOHEXANONES, CYCLOHEXENES , MOLECULAR ISOMERISM, ORGANIC SOLVENTS, GAS CHROMATOGRAPHY

  20. Triethylborane-induced radical reactions with gallium hydride reagent HGaCl2.

    Science.gov (United States)

    Mikami, S; Fujita, K; Nakamura, T; Yorimitsu, H; Shinokubo, H; Matsubara, S; Oshima, K

    2001-06-14

    [see reaction]. A gallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source.

  1. Barium carbonate as an agent to improve the electrical properties of neodymium-barium-copper system at high temperature

    International Nuclear Information System (INIS)

    Fernandes, J.P.; Duarte, G.W.; Caldart, C.; Kniess, C.T.; Montedo, O.R.K.; Rocha, M.R.; Riella, H.G.; Fiori, M.A.

    2015-01-01

    Specialized ceramics are manufactured under special conditions and contain specific elements. They possess unique electrical and thermal properties and are frequently used by the electronics industry. Ceramics containing neodymium-barium-copper (NBC) exhibit high conductivities at low temperatures. NBC-based ceramics are typically combined with oxides, i.e., NBCo produced from neodymium oxide, barium oxide and copper oxide. This study presents NBC ceramics that were produced with barium carbonate, copper oxide and neodymium oxide (NBCa) as starting materials. These ceramics have good electrical conductivities at room temperature. Their conductivities are temperature dependent and related to the starting amount of barium carbonate (w%). - Highlights: • The new crystalline structure were obtained due presence of the barium carbonate. • The NBCa compound has excellent electrical conductivity at room temperature. • The grain crystalline morphology was modified by presence of the barium carbonate. • New Phases α and β were introduced by carbonate barium in the NBC compound

  2. Initiation of delayed hydride cracking in zirconium-2.5 wt% niobium

    International Nuclear Information System (INIS)

    Shalabi, A.F.; Meneley, D.A.

    1990-01-01

    Delayed hydride cracking in zirconium alloys is caused by the repeated precipitation and cracking of brittle hydrides. The growth kinetic of the hydrides have been measured to evaluate the critical hydride length for crack initiation. Hydride growth leading to crack initiation follows an approximate (time) 1/3 law on the average; crack propagation proceeds in a stepwise fashion. The critical length of hydride for crack initiation increases with stress and temperature. The fracture criterion for crack initiation predicts the critical hydride length at a give stress level and temperature. The fracture initiation mechanism of the hydride confirms the temperature effects for heating and cooling cycles under services loads. (orig.)

  3. Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed

    Directory of Open Access Journals (Sweden)

    Thirugnasambandam G. Manivasagam

    2012-10-01

    Full Text Available As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase hydrogen loading, provides precise control with only moderate reaction conditions. Interestingly, the alloy composition determines the crystallographic nature of the metal-hydride: a structural change is induced from rutile to fluorite at 80 at.% of Mg in Mg-TM alloy, with ensuing improved hydrogen mobility and storage capacity. So far, 6 wt.% (equivalent to 1600 mAh/g of reversibly stored hydrogen in MgyTM(1-yHx (TM: Sc, Ti has been reported. Thin film forms of these metal-hydrides reveal interesting electrochromic properties as a function of hydrogen content. Optical switching occurs during (dehydrogenation between the reflective metal and the transparent metal hydride states. The chronological sequence of the optical improvements in optically active metal hydrides starts with the rare earth systems (YHx, followed by Mg rare earth alloy hydrides (MgyGd(1-yHx and concludes with Mg transition metal hydrides (MgyTM(1-yHx. In-situ optical characterization of gradient thin films during (dehydrogenation, denoted as hydrogenography, enables the monitoring of alloy composition gradients simultaneously.

  4. Pyrophoric behaviour of uranium hydride and uranium powders

    Science.gov (United States)

    Le Guyadec, F.; Génin, X.; Bayle, J. P.; Dugne, O.; Duhart-Barone, A.; Ablitzer, C.

    2010-01-01

    Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (Oxidation mechanisms are proposed.

  5. Ultra-sonic observation in niobium hydride precipitation

    International Nuclear Information System (INIS)

    Florencio, O.; Pinatti, Dyonisio G.

    1982-01-01

    The hidrogen embrittlement of exothermic ocluders, had been considered as due to applied stress induced hydride precipitates leading to brittle fracture. The results of simultaneous measurements of macroscopic deformation and elastic change due to hydride precipitation, using the ultrasonic pulse-echo technique are showed. THen it was tested the possibility of kinectis precipitation parameters evoluation. (Author) [pt

  6. Creating nanoshell on the surface of titanium hydride bead

    Directory of Open Access Journals (Sweden)

    PAVLENKO Vyacheslav Ivanovich

    2016-12-01

    Full Text Available The article presents data on the modification of titanium hydride bead by creating titanium nanoshell on its surface by ion-plasma vacuum magnetron sputtering. To apply titanium nanoshell on the titanium hydride bead vacuum coating plant of multifunctional nanocomposite coatings QVADRA 500 located in the center of high technology was used. Analysis of the micrographs of the original surface of titanium hydride bead showed that the microstructure of the surface is flat, smooth, in addition the analysis of the microstructure of material surface showed the presence of small porosity, roughness, mainly cavities, as well as shallow longitudinal cracks. The presence of oxide film in titanium hydride prevents the free release of hydrogen and fills some micro-cracks on the surface. Differential thermal analysis of both samples was conducted to determine the thermal stability of the initial titanium hydride bead and bead with applied titanium nanoshell. Hydrogen thermal desorption spectra of the samples of the initial titanium hydride bead and bead with applied titanium nanoshell show different thermal stability of compared materials in the temperature range from 550 to 860о C. Titanium nanoshells applied in this way allows increasing the heat resistance of titanium hydride bead – the temperature of starting decomposition is 695о C and temperature when decomposition finishes is more than 1000о C. Modified in this way titanium hydride bead can be used as a filler in the radiation protective materials used in the construction or upgrading biological protection of nuclear power plants.

  7. Nanoparticles of barium induce apoptosis in human phagocytes.

    Science.gov (United States)

    Mores, Luana; França, Eduardo Luzia; Silva, Núbia Andrade; Suchara, Eliane Aparecida; Honorio-França, Adenilda Cristina

    2015-01-01

    Nutrients and immunological factors of breast milk are essential for newborn growth and the development of their immune system, but this secretion can contain organic and inorganic toxins such as barium. Colostrum contamination with barium is an important issue to investigate because this naturally occurring element is also associated with human activity and industrial pollution. The study evaluated the administration of barium nanoparticles to colostrum, assessing the viability and functional activity of colostral mononuclear phagocytes. Colostrum was collected from 24 clinically healthy women (aged 18-35 years). Cell viability, superoxide release, intracellular Ca(2+) release, and phagocyte apoptosis were analyzed in the samples. Treatment with barium lowered mononuclear phagocyte viability, increased superoxide release, and reduced intracellular calcium release. In addition, barium increased cell death by apoptosis. These data suggest that nanoparticles of barium in colostrum are toxic to cells, showing the importance of avoiding exposure to this element.

  8. Deflocculants for Tape Casting Barium Titanate.

    Science.gov (United States)

    1983-07-01

    are discussed in detail by Mitchell and Smith (2). The measurement of free and bound water was performed by titration to an electrometric end point by...the dead- stop ( biamperometric ) technique using a Fisher Model 391 aquametry apparatus. The fundamental theory behind this technique is reviewed p in... Titrations were performed at 25 ± 10C. "i 9 For insoluble materials, such as the barium titanate powder, the solid was added to the pyridine solvent

  9. ORNL Interim Progress Report on Hydride Reorientation CIRFT Tests

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yan, Yong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-28

    A systematic study of H. B. Robinson (HBR) high burnup spent nuclear fuel (SNF) vibration integrity was performed in Phase I project under simulated transportation environments, using the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT) hot cell testing technology developed at Oak Ridge National Laboratory in 2013–14. The data analysis on the as-irradiated HBR SNF rods demonstrated that the load amplitude is the dominant factor that controls the fatigue life of bending rods. However, previous studies have shown that the hydrogen content and hydride morphology has an important effect on zirconium alloy mechanical properties. To address the effect of radial hydrides in SNF rods, in Phase II a test procedure was developed to simulate the effects of elevated temperatures, pressures, and stresses during transfer-drying operations. Pressurized and sealed fuel segments were heated to the target temperature for a preset hold time and slow-cooled at a controlled rate. The procedure was applied to both non-irradiated/prehydrided and high-burnup Zircaloy-4 fueled cladding segments using the Nuclear Regulatory Commission-recommended 400°C maximum temperature limit at various cooling rates. Before testing high-burnup cladding, four out-of-cell tests were conducted to optimize the hydride reorientation (R) test condition with pre-hydride Zircaloy-4 cladding, which has the same geometry as the high burnup fuel samples. Test HR-HBR#1 was conducted at the maximum hoop stress of 145 MPa, at a 400°C maximum temperature and a 5°C/h cooling rate. On the other hand, thermal cycling was performed for tests HR-HBR#2, HR-HBR#3, and HR-HBR#4 to generate more radial hydrides. It is clear that thermal cycling increases the ratio of the radial hydride to circumferential hydrides. The internal pressure also has a significant effect on the radial hydride morphology. This report describes a procedure and experimental results of the four out-of-cell hydride reorientation tests of

  10. Modular hydride beds for mobile applications

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, M.E.; Stewart, K.D.

    1997-08-01

    Design, construction, initial testing and simple thermal modeling of modular, metal hydride beds have been completed. Originally designed for supplying hydrogen to a fuel cell on a mobile vehicle, the complete bed design consists of 8 modules and is intended for use on the Palm Desert Vehicle (PDV) under development at the Schatz Energy Center, Humbolt State University. Each module contains approximately 2 kg of a commercially available, low temperature, hydride-forming metal alloy. Waste heat from the fuel cell in the form of heated water is used to desorb hydrogen from the alloy for supplying feed hydrogen to the fuel cell. In order to help determine the performance of such a modular bed system, six modules were constructed and tested. The design and construction of the modules is described in detail. Initial testing of the modules both individually and as a group showed that each module can store {approximately} 30 g of hydrogen (at 165 PSIA fill pressure, 17 C), could be filled with hydrogen in 6 minutes at a nominal, 75 standard liters/min (slm) fueling rate, and could supply hydrogen during desorption at rates of 25 slm, the maximum anticipated hydrogen fuel cell input requirement. Tests made of 5 modules as a group indicated that the behavior of the group run in parallel both in fueling and gas delivery could be directly predicted from the corresponding, single module characteristics by using an appropriate scaling factor. Simple thermal modeling of a module as an array of cylindrical, hydride-filled tubes was performed. The predictions of the model are in good agreement with experimental data.

  11. Barium hexaferrite nanoparticles: Synthesis and magnetic properties

    International Nuclear Information System (INIS)

    Martirosyan, K.S.; Galstyan, E.; Hossain, S.M.; Wang Yiju; Litvinov, D.

    2011-01-01

    Carbon combustion synthesis is applied to rapid and energy efficient fabrication of crystalline barium hexaferrite nanoparticles with the average particle size of 50-100 nm. In this method, the exothermic oxidation of carbon nanoparticles with an average size of 5 nm with a surface area of 80 m 2 /g generates a self-propagating thermal wave with maximum temperatures of up to 1000 deg. C. The thermal front rapidly propagates through the mixture of solid reactants converting it to the hexagonal barium ferrite. Carbon is not incorporated in the product and is emitted from the reaction zone as a gaseous CO 2 . The activation energy for carbon combustion synthesis of BaFe 12 O 19 was estimated to be 98 kJ/mol. A complete conversion to hexagonal barium ferrite is obtained for carbon concentration exceeding 11 wt.%. The magnetic properties H c ∼3000 Oe and M s ∼50.3 emu/g of the compact sintered ferrites compare well with those produced by other synthesis methods.

  12. BARIUM REDUCTION OF INTUSSUSCEPTION IN INFANCY

    Science.gov (United States)

    Denenholz, Edward J.; Feher, George. S.

    1955-01-01

    Barium enema reduction was used as the initial routine treatment in 29 infants with intussusception. In 22 of them the intussusception was reduced by this means. In three of eight patients operated upon the intussusception was found to be reduced. Four of the remaining five patients had clinical or x-ray evidence of complications before reduction by barium enema was attempted. Twenty-one of the patients, all of whom were observed in private practice, were treated without admission to the hospital. After reduction, these patients were observed closely by the clinician. None of these patients showed clinical or x-ray signs of complications before reduction. Certain clinical and roentgen criteria must be satisfied before it can be concluded that reduction by barium enema is complete. If there are clinical signs of complications with x-ray evidence of small bowel obstruction, only a very cautious attempt at hydrostatic reduction should be made. As the time factor is generally a reliable clinical guide to reducibility, the late cases should be viewed with greater caution. Long duration of symptoms, however, is not per se a contraindication to an attempt at hydrostatic reduction. PMID:13230908

  13. Determination of a massive zirconium hydride production cycle

    International Nuclear Information System (INIS)

    Loche, J.-P.

    1979-06-01

    This note includes: a bibliographical study on the physical, chemical and metallurgical properties of zirconium and its hydride, a brief review of the different methods of zirconium hydride conditioning and a more detailed study of the conditioning process by massive hydride formation. A systematic study was devoted to the thermal method of hydrogen incorporation with a view to obtaining articles of homogeneous composition and of hydrogen concentration as close as possible to the formula ZrH 2 . This was achieved by original tests designed to measure the plasticity of the metal or of its hydride during the process. The hydride formation cycle considered optimum is described for an initial metal of carefully selected chemical and metallurgical properties [fr

  14. Effects of Barium Concentration on Oropharyngeal Swallow Timing Measures

    OpenAIRE

    Stokely, Shauna L.; Molfenter, Sonja M.; Steele, Catriona M.

    2013-01-01

    Videofluoroscopy is commonly used for evaluating oropharyngeal swallowing but requires radiopaque contrast (typically barium). Prior studies suggest that some aspects of swallowing, including timing measures of oral and pharyngeal bolus transit, vary depending on barium concentration. The aim of our study was to identify timing differences in healthy swallowing between “thin” (40 % w/v concentration) and “ultrathin” (22 % w/v concentration) barium solutions. Twenty healthy adults (Ten women; ...

  15. Contrast characteristics of barium preparations and the timing of exposure

    OpenAIRE

    渋谷, 光一; 中桐, 義忠; 東, 義晴; 杉田, 勝彦; 小橋, 高郎; 大倉, 保彦; 丹谷, 延義; 三上, 泰隆; 平木, 祥夫

    1995-01-01

    We studied the relationship between the contrast characteristics of barium suspension and timing of exposure. We poured several kinds of barium preparations on the phantom manufactured by ourselves, and took X-ray pictures continuously by a DSA system. We analyzed each of the characteris-tics of the contrast. The time which was reguired for the contrast to reach the peak (Contrast Peak Time ; CPT) was unrelated with the kind of barium preparations used. It depended on the viscosity of the con...

  16. Barium peritonitis following upper gastrointestinal series: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Su Jin; Hwang, Ji Young; Kim, Yong Jin; Hong, Seong Sook [Soonchunhyang University College of Medicine, Seoul Hospital, Seoul (Korea, Republic of)

    2017-06-15

    We report a rare case of barium peritonitis following an upper gastrointestinal (GI) series and its imaging findings in a 74-year-old female. Barium peritonitis is a rare but life-threatening complication of GI contrast investigation. Therefore, clinical awareness of barium peritonitis as a complication of GI tract contrast investigation would help to prevent such a complication and manage the patients properly.

  17. Surface melting of deuterium hydride thick films

    OpenAIRE

    Zeppenfeld, P.; Bienfait, M.; Feng Chuan Liu,; Vilches, O.E.; Coddens, G.

    1990-01-01

    Quasi-elastic neutron scattering has been used to measure, below the bulk melting temperature, the thickness and the diffusion coefficient of the mobile surface layer of 8 and 10 layer thick films of deuterium hydride (HD) condensed on MgO(100). The measurements show that the close-packed surface of solid HD surface melts gradually, with the thickness of the melted layer increasing from 0.5 to 6 molecular layers as the temperature rises from 4 K to 0.05 K below the bulk melting temperature. T...

  18. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

    Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf

    2002-01-01

    , explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... hydrogen absorption/desorption reaction. To approximate the experimental data, equations describing the current distribution in porous electrodes were needed. Indications of one or more parallel reduction/oxidation processes competing with the electrochemical hydrogen absorption/desorption reaction were...

  19. Nanoindentation measurements of the mechanical properties of zirconium matrix and hydrides in unirradiated pre-hydrided nuclear fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Rico, A., E-mail: alvaro.rico@urjc.es [DIMME, Departamento de Tecnología Mecánica, Universidad Rey Juan Carlos, c/Tulipán s/n, E-28933 Móstoles, Madrid (Spain); Martin-Rengel, M.A., E-mail: mamartin@mater.upm.es [Departamento de Ciencia de los Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, Profesor Aranguren SN, E-28040 Madrid (Spain); Ruiz-Hervias, J., E-mail: jesus.ruiz@upm.es [Departamento de Ciencia de los Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, Profesor Aranguren SN, E-28040 Madrid (Spain); Rodriguez, J. [DIMME, Departamento de Tecnología Mecánica, Universidad Rey Juan Carlos, c/Tulipán s/n, E-28933 Móstoles, Madrid (Spain); Gomez-Sanchez, F.J., E-mail: javier.gomez@amsimulation.com [Advanced Material Simulation, S.L, Madrid (Spain)

    2014-09-15

    It is well known that the mechanical properties of the nuclear fuel cladding may be affected by the presence of hydrides. The average mechanical properties of hydrided cladding have been extensively investigated from a macroscopic point of view. In addition, the mechanical and fracture properties of bulk hydride samples fabricated from zirconium plates have also been reported. In this paper, Young’s modulus, hardness and yield stress are measured for each phase, namely zirconium hydrides and matrix, of pre-hydrided nuclear fuel cladding. To this end, nanoindentation tests were performed on ZIRLO samples in as-received state, on a hydride blister and in samples with 150 and 1200 ppm of hydrogen homogeneously distributed along the hoop direction of the cladding. The results show that the measured mechanical properties of the zirconium hydrides and ZIRLO matrix (Young’s modulus, hardness and yield stress) are rather similar. From the experimental data, the hydride volume fraction in the cladding samples with 150 and 1200 ppm was estimated and the average mechanical properties were calculated by means of the rule of mixtures. These values were compared with those obtained from ring compression tests. Good agreement between the results obtained by both methods was found.

  20. Nanoindentation measurements of the mechanical properties of zirconium matrix and hydrides in unirradiated pre-hydrided nuclear fuel cladding

    International Nuclear Information System (INIS)

    Rico, A.; Martin-Rengel, M.A.; Ruiz-Hervias, J.; Rodriguez, J.; Gomez-Sanchez, F.J.

    2014-01-01

    It is well known that the mechanical properties of the nuclear fuel cladding may be affected by the presence of hydrides. The average mechanical properties of hydrided cladding have been extensively investigated from a macroscopic point of view. In addition, the mechanical and fracture properties of bulk hydride samples fabricated from zirconium plates have also been reported. In this paper, Young’s modulus, hardness and yield stress are measured for each phase, namely zirconium hydrides and matrix, of pre-hydrided nuclear fuel cladding. To this end, nanoindentation tests were performed on ZIRLO samples in as-received state, on a hydride blister and in samples with 150 and 1200 ppm of hydrogen homogeneously distributed along the hoop direction of the cladding. The results show that the measured mechanical properties of the zirconium hydrides and ZIRLO matrix (Young’s modulus, hardness and yield stress) are rather similar. From the experimental data, the hydride volume fraction in the cladding samples with 150 and 1200 ppm was estimated and the average mechanical properties were calculated by means of the rule of mixtures. These values were compared with those obtained from ring compression tests. Good agreement between the results obtained by both methods was found

  1. Effects of barium concentration on oropharyngeal swallow timing measures.

    Science.gov (United States)

    Stokely, Shauna L; Molfenter, Sonja M; Steele, Catriona M

    2014-02-01

    Videofluoroscopy is commonly used for evaluating oropharyngeal swallowing but requires radiopaque contrast (typically barium). Prior studies suggest that some aspects of swallowing, including timing measures of oral and pharyngeal bolus transit, vary depending on barium concentration. The aim of our study was to identify timing differences in healthy swallowing between "thin" (40 % w/v concentration) and "ultrathin" (22 % w/v concentration) barium solutions. Twenty healthy adults (Ten women; mean age = 31 years) each performed a series of three noncued 5-ml swallows each of ultrathin and thin liquid barium solutions in videofluoroscopy. Timing measures were compared between barium concentrations using a mixed-model ANOVA. The measures of interest were stage transition duration, pharyngeal transit time, and duration of upper esophageal sphincter opening. Significant differences were observed in the timing measures of swallowing with respect to barium concentration. In all cases, longer durations were seen with the higher barium concentration. Barium concentration influences timing parameters in healthy swallowing, even between ultrathin and thin concentrations. Clinicians need to understand and control for the impact of different barium stimuli on swallowing physiology.

  2. History and challenges of barium titanate: Part II

    Directory of Open Access Journals (Sweden)

    Vijatović M.M.

    2008-01-01

    Full Text Available Barium titanate is the first ferroelectric ceramics and a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Barium titanate is a member of a large family of compounds with the general formula ABO3 which is called perovskite. Barium titanate can be prepared using different methods. The synthesis method depends on the desired characteristics for the end application and the method used has a significant influence on the structure and properties of barium titanate materials. In this review paper, in Part II the properties of obtained materials and their application are presented.

  3. History and challenges of barium titanate: Part I

    Directory of Open Access Journals (Sweden)

    Vijatović M.M.

    2008-01-01

    Full Text Available Barium titanate is the first ferroelectric ceramics and a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Barium titanate is a member of a large family of compounds with the general formula ABO3 called perovskites. Barium titanate can be prepared using different methods. The synthesis method depends on the desired characteristics for the end application. The used method has a significant influence on the structure and properties of barium titanate materials. In this review paper, Part I contains a study of the BaTiO3 structure and frequently used synthesis methods.

  4. Impact of the barium enema examination on patient management

    International Nuclear Information System (INIS)

    Chen, Y.M.; Ott, D.J.; Munitz, H.A.; Gelfand, D.W.

    1986-01-01

    The records of 214 patients who underwent barium enema examinations were reviewed. Indications for the examination, radiographic efficacy, and patient outcome were correlated to determine the impact of barium enema examination on patient management. The most frequent indications were rectal bleeding (33%), abdominal pain (31%), and anemia (17%). Diverticulosis (30%), polyps (10%), and malignancies (12%) were the most common abnormalities detected. The sensitivity of barium enema examination for detecting neoplasms was 89%. The effects on patient management were as follows: serious pathology was excluded (64%); a diagnosis was made that changed therapy (24%); existing therapy was continued (10%); additional studies were ordered (2%). No serious lesion was missed on barium enema examination

  5. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  6. Electrooptic modulation in thin film barium titanate plasmonic interferometers.

    Science.gov (United States)

    Dicken, Matthew J; Sweatlock, Luke A; Pacifici, Domenico; Lezec, Henri J; Bhattacharya, Kaushik; Atwater, Harry A

    2008-11-01

    We demonstrate control of the surface plasmon polariton wavevector in an active metal-dielectric plasmonic interferometer by utilizing electrooptic barium titanate as the dielectric layer. Arrays of subwavelength interferometers were fabricated from pairs of parallel slits milled in silver on barium titanate thin films. Plasmon-mediated transmission of incident light through the subwavelength slits is modulated by an external voltage applied across the barium titanate thin film. Transmitted light modulation is ascribed to two effects, electrically induced domain switching and electrooptic modulation of the barium titanate index.

  7. NATO Advanced Study Institute on Metal Hydrides

    CERN Document Server

    1981-01-01

    In the last five years, the study of metal hydrides has ex­ panded enormously due to the potential technological importance of this class of materials in hydrogen based energy conversion schemes. The scope of this activity has been worldwide among the industrially advanced nations. There has been a consensus among researchers in both fundamental and applied areas that a more basic understanding of the properties of metal/hydrogen syster;,s is required in order to provide a rational basis for the selection of materials for specific applications. The current worldwide need for and interest in research in metal hydrides indicated the timeliness of an Advanced Study Insti­ tute to provide an in-depth view of the field for those active in its various aspects. The inclusion of speakers from non-NATO coun­ tries provided the opportunity for cross-fertilization of ideas for future research. While the emphasis of the Institute was on basic properties, there was a conscious effort to stimulate interest in the applic...

  8. Neutron scattering on hydrides of intermetallic compounds

    International Nuclear Information System (INIS)

    Hempelmann, R.

    1986-11-01

    This review surveys the application of neutron scattering for the investigation of the microscopic behaviour of hydrogen in intermetallic compounds. This concerns the structure as well as the dynamics. Neutron diffraction experiments were performed on Ti 1.2 Mn 1.8 D 3 and LaNi 5 D 7 . In the latter case the dominant nickel scattering could be suppressed by isotope substitution with 60 Ni, and the anisotropic broadening of the Bragg peaks could be modelled in a correspondingly modified Rietveld-profile refinement. For the investigation of hydrogen diffusion in intermetallic hydrides by means of quasielastic neutron scattering an iterative multiple scattering correction procedure has been developped which allows a reliable determination of hydrogen diffusion coefficients. The mechanism of hydrogen diffusion in intermetallic hydrides comprises three types of jumps: escape jumps out of energetically lower interstitials, transport jumps over the energetically higher sites and locally restricted jump processes. For Ti 1.2 Mn 1.8 H 3 the main features of the diffusional behaviour could be described quantitatively in the framework of a three state model. By means of neutron vibrational spectroscopy information about the occupied hydrogen sites and thus about the structure can be extracted from the symmetry splitting of the vibrational modes. In this way we showed that in α-LaNi 5 H x , La 2 Ni 4 -octahedral and La 2 Ni 2 -tetrahedral interstitial sites are occupied. (orig./GG)

  9. Binding and leakage of barium in alginate microbeads.

    Science.gov (United States)

    Mørch, Yrr A; Qi, Meirigeng; Gundersen, Per Ole M; Formo, Kjetil; Lacik, Igor; Skjåk-Braek, Gudmund; Oberholzer, Jose; Strand, Berit L

    2012-11-01

    Microbeads of alginate crosslinked with Ca(2+) and/or Ba(2+) are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared with high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. To reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation. Copyright © 2012 Wiley Periodicals, Inc.

  10. 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

  11. Gluten content of barium sulfate suspensions used for barium swallows in patients with celiac disease.

    Science.gov (United States)

    Chiu, Jennifer G; Shin, Yoona; Patel, Priti N; Mangione, Robert A

    2014-01-01

    To determine the availability and accuracy of information provided by hospitals, imaging centers, and manufacturers regarding gluten in barium sulfate suspensions. A total of 105 facilities were contacted via telephone to determine the gluten content of the contrast media used in those facilities. Manufacturers were contacted and their Web sites reviewed to determine the gluten content of their barium products. Thirty-nine percent of the hospitals and 52% of the imaging centers were not aware of the gluten content of the contrast media they used. Twenty-nine-and-a-half percent of the respondents provided the correct gluten content. The manufacturers noted that 5 products were tested and confirmed gluten free, 1 product was not tested but described as gluten free, 1 product's gluten content depended upon its flavor, and 1 product was reported to contain gluten. Clinicians caring for patients with celiac disease or patients who choose to restrict their gluten consumption must ensure that the barium sulfate suspension ingested is gluten free. It can be difficult to determine the gluten content of barium sulfate, as a majority of radiology departments and imaging centers did not know whether the product they use is gluten free. Educating staff members and improving product labeling would benefit the quality of care provided to patients with celiac disease.

  12. Hydrogen storage in metal hydrides and complex hydrides; Wasserstoffspeicherung in Metall- und komplexen Hydriden - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Bielmann, M.; Zuettel, A.

    2007-07-01

    This final report for the Swiss Federal Office of Energy (SFOE), reports on work done in 2007 at the Swiss Federal Laboratories for Materials Science and Technology EMPA on the storage of hydrogen in metal hydrides and complex hydrides. In particular, the use of tetrahydroborates is noted. The potential of this class of materials is stressed. The structures at room-temperature were examined using neutron and X-ray diffraction methods. Thermodynamic methods helped determine the thermodynamic stability of the materials. Also, a complete energy diagram for the materials was developed. The use of silicon oxide to reduce activation energy and its catalytic effects are discussed. The challenges placed by desorption mechanisms are noted. The authors note that reversibility is basically proven.

  13. Finite difference program for calculating hydride bed wall temperature profiles

    International Nuclear Information System (INIS)

    Klein, J.E.

    1992-01-01

    A QuickBASIC finite difference program was written for calculating one dimensional temperature profiles in up to two media with flat, cylindrical, or spherical geometries. The development of the program was motivated by the need to calculate maximum temperature differences across the walls of the Tritium metal hydrides beds for thermal fatigue analysis. The purpose of this report is to document the equations and the computer program used to calculate transient wall temperatures in stainless steel hydride vessels. The development of the computer code was motivated by the need to calculate maximum temperature differences across the walls of the hydrides beds in the Tritium Facility for thermal fatigue analysis

  14. Investigation process of alcoholysis of hydride aluminium-adobe

    International Nuclear Information System (INIS)

    Numanov, M.I.; Normatov, I.Sh.; Mirsaidov, U.M.

    2001-01-01

    Considering of that process of acid treatment of aluminium-adobe hydride realizes in the ethyl alcohol media it was necessary study the process of alcoholysis of AlH 3 and aluminium additives. In the end of article authors became to conclusion that deficiency of spontaneous alcoholysis of AlH 3 in adobe caused by protective action of fiber; solvate ability of LiCl and alkoxy aluminium hydride of lithium-LiCl·CO 2 H 5 OH, Li Al(OC 2 H 5 ) 4 ·nC 2 H 5 OH decreasing the expectancy of responding of alcohol with aluminium hydride

  15. Comparison of barium and gastrograffin swallow for radiation ...

    African Journals Online (AJOL)

    using radio-opaque contrast is a standard step in treatment planning prior to delivering radiation therapy. Various contrast mediums such as barium, gastrograffin and hexabrix have been used for simulation at different centres. Objective. The purpose of the study was to compare barium and gastrograffin as a useful and ...

  16. Study on the preparation and formation mechanism of barium ...

    Indian Academy of Sciences (India)

    This paper reports a simple method to prepare barium sulphate nanoparticles by use of tetradecanoic acid, hexadecanoic acid and stearic acid as modifier. The barium sulphate nanoparticles obtained are characterized by using Fourier transform infra-red spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission ...

  17. Outcome of barium enema in patients with colorectal symptoms ...

    African Journals Online (AJOL)

    Background: For many years, double contrast barium enema has been an effective way to evaluate the large bowel. With the development of the colonoscope, the role of barium enema has been questioned. However it is still useful in investigating patients with colorectal symptoms especially in the developing world where ...

  18. Application of magnesium hydroxide and barium hydroxide for the ...

    African Journals Online (AJOL)

    Application of magnesium hydroxide and barium hydroxide for the removal of metals and sulphate from mine water. ... equivalent to the Ba(OH)2 dosage. During CO2-dosing, CaCO3 is precipitated to the saturation level of CaCO3. Keywords: Magnesium hydroxide; barium hydroxide; sulphate removal; water treatment ...

  19. Barium enema findings of milk allergy in infants

    International Nuclear Information System (INIS)

    Kim, Gyoung Ju; Kim, Mi Jeong; Lee, Hee Jung

    2006-01-01

    We wanted to evaluate the barium enema findings of milk allergy in infants. Retrospective evaluation of the plain abdominal radiography and barium enema findings was performed in fifteen young infants suffering with milk allergy. The presence of gaseous distension, rectal gas, paralytic ileus and mechanical obstruction was evaluated on the plain radiography. The presence of spasm, a transitional zone, a reversed rectosigmoid index and mucosal irregularity was analyzed on the barium enema; the presence of barium retention was also evaluated on 24-hour-delayed plain radiography. Paralytic ileus was the most common finding on the plain radiography (93%). On the barium enema, continuous spasm of the colon, ranging from the rectum to the descending colon, was revealed in ten infants (67%). A transitional zone was observed in one infant and a reversed rectosigmoid index was revealed in four. Mucosal irregularity was observed in two infants. Barium retention was demonstrated in 11 of fifteen cases: throughout the entire colon (n = 3), from the rectum to the descending colon (n = 7), and up to the transverse colon (n = 1). The most common barium enema finding of milk allergy in infants was spasm of the distal colon. The other findings were a transitional zone, a reversed rectosigmoid index, mucosal irregularity and barium retention

  20. Ab initio studies on the electronic structure and properties of aluminum hydrides that are analogues of boron hydrides.

    Science.gov (United States)

    Srinivasu, K; Chandrakumar, K R S; Ghosh, Swapan K

    2010-11-25

    Although the boron hydrides are well-known in the literature, the aluminum hydride chemistry is limited to very few systems such as AlH(3), its dimer, and its polymeric form. In view of the recent experimental studies on the possible existence of the aluminum hydrides, herein, we have undertaken a systematic study on the electronic structure and properties of these aluminum hydrides. Under this, we have studied different classes of hydrides, viz., closo (Al(n)H(n+2)), nido (Al(n)H(n+4)), and arachno (Al(n)H(n+6)), similar to the boranes. All the aluminum hydrides are found to have exceptionally large highest-occupied molecular orbital-lowest-unoccupied molecular orbital gaps, low electron affinities, large ionization potentials and also large enthalpy and free energy of atomization. In addition, most of the structures are also found to have high symmetries. These exceptional properties can be indicative of the pronounced stability, and hence, it is expected that other aluminum hydride complexes can indeed be observed experimentally.

  1. High Growth Rate Hydride Vapor Phase Epitaxy at Low Temperature through Use of Uncracked Hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Schulte, Kevin L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Simon, John D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ptak, Aaron J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Braun, Anna [Rose-Hulman Institute of Technology

    2018-01-22

    We demonstrate hydride vapor phase epitaxy (HVPE) of GaAs with unusually high growth rates (RG) at low temperature and atmospheric pressure by employing a hydride-enhanced growth mechanism. Under traditional HVPE growth conditions that involve growth from Asx species, RG exhibits a strong temperature dependence due to slow kinetics at the surface, and growth temperatures >750 degrees C are required to obtain RG > 60 um/h. We demonstrate that when the group V element reaches the surface in a hydride, the kinetic barrier is dramatically reduced and surface kinetics no longer limit RG. In this regime, RG is dependent on mass transport of uncracked AsH3 to the surface. By controlling the AsH3 velocity and temperature profile of the reactor, which both affect the degree of AsH3 decomposition, we demonstrate tuning of RG. We achieve RG above 60 um/h at temperatures as low as 560 degrees C and up to 110 um/h at 650 degrees C. We incorporate high-RG GaAs into solar cell devices to verify that the electronic quality does not deteriorate as RG is increased. The open circuit voltage (VOC), which is a strong function of non-radiative recombination in the bulk material, exhibits negligible variance in a series of devices grown at 650 degrees C with RG = 55-110 um/h. The implications of low temperature growth for the formation of complex heterostructure devices by HVPE are discussed.

  2. Short-cavity squeezing in barium

    Science.gov (United States)

    Hope, D. M.; Bachor, H-A.; Manson, P. J.; Mcclelland, D. E.

    1992-01-01

    Broadband phase sensitive noise and squeezing were experimentally observed in a system of barium atoms interacting with a single mode of a short optical cavity. Squeezing of 13 +/- 3 percent was observed. A maximum possible squeezing of 45 +/- 8 percent could be inferred for out experimental conditions, after correction for measured loss factors. Noise reductions below the quantum limit were found over a range of detection frequencies 60-170 MHz and were best for high cavity transmission and large optical depths. The amount of squeezing observed is consistent with theoretical predictions from a full quantum statistical model of the system.

  3. Dielectric properties of barium titanate supramolecular nanocomposites.

    Science.gov (United States)

    Lee, Keun Hyung; Kao, Joseph; Parizi, Saman Salemizadeh; Caruntu, Gabriel; Xu, Ting

    2014-04-07

    Nanostructured dielectric composites can be obtained by dispersing high permittivity fillers, barium titanate (BTO) nanocubes, within a supramolecular framework. Thin films of BTO supramolecular nanocomposites exhibit a dielectric permittivity (εr) as high as 15 and a relatively low dielectric loss of ∼0.1 at 1 kHz. These results demonstrate a new route to control the dispersion of high permittivity fillers toward high permittivity dielectric nanocomposites with low loss. Furthermore, the present study shows that the size distribution of nanofillers plays a key role in their spatial distribution and local ordering and alignment within supramolecular nanostructures.

  4. Structural and Dynamical Properties of Barium Stannate

    Science.gov (United States)

    Phelan, D.; Krogstad, M. J.; Lopez-Bezanilla, A.; Parshall, D.; Gim, Y.; Cooper, S. L.; Zheng, H.

    Barium stannate based perovskites have recently drawn attention due to their potential as transparent conducting oxides and reports of high carrier mobility in La-doped single crystals. Published DFT calculations and experimental results have suggested phonon instabilities at high symmetry zone boundary positions and local octahedral rotations, respectively, for BaSnO3. Here, we discuss recent structural measurements of BaSnO3, in which we have searched for such distortions by employing a combination of single crystal neutron diffraction and total scattering analysis of powder neutron diffraction. Moreover, we discuss lattice dynamical measurements, comparing phonon dispersion measurements to DFT calculations.

  5. Short-cavity squeezing in barium

    International Nuclear Information System (INIS)

    Hope, D.M.; Bachor, H-A.; Manson, P.J.; Mcclelland, D.E.

    1992-01-01

    Broadband phase sensitive noise and squeezing were experimentally observed in a system of barium atoms interacting with a single mode of a short optical cavity. Squeezing of 13 +/- 3 percent was observed. A maximum possible squeezing of 45 +/- 8 percent could be inferred for out experimental conditions, after correction for measured loss factors. Noise reductions below the quantum limit were found over a range of detection frequencies 60-170 MHz and were best for high cavity transmission and large optical depths. The amount of squeezing observed is consistent with theoretical predictions from a full quantum statistical model of the system

  6. Barium and radium migration in unconsolidated Canadian geological materials

    International Nuclear Information System (INIS)

    Gillham, R.W.; Sharma, H.D.; Reddy, M.R.; Cooper, E.L.; Cherry, J.A.

    1981-05-01

    This report describes the results of laboratory studies on the distribution coefficients of radium and barium in samples of unconsolidated geologic materials. Graphs of Ksub(d) versus solution concentration for the respective elements showed constant Ksub(d) values in the low concentration range suggesting that, at low concentrations, a distribution coefficient is a valid means of representing the geochemical reactions of both barium and radium. The Ksub(d) values for barium range between 60 and 3500 ml/g. The values appear to be influenced by the amount of barium occurring naturally in the soil materials and thus there is little possiblility of using barium as an analog of radium in laboratory experiments. The Ksub(d) values of radium vary from 50 to 1000 ml/g indicating that a wide range of geological materials have a substantial capacity to retard the migration of radium

  7. Process for production of a metal hydride

    Science.gov (United States)

    Allen, Nathan Tait; Butterick, III, Robert; Chin, Arthur Achhing; Millar, Dean Michael; Molzahn, David Craig

    2014-08-12

    A process for production of a metal hydride compound MH.sub.x, wherein x is one or two and M is an alkali metal, Be or Mg. The process comprises combining a compound of formula (R.sup.1O).sub.xM with aluminum, hydrogen and at least one metal selected from among titanium, zirconium, hafnium, niobium, vanadium, tantalum and iron to produce a compound of formula MH.sub.x. R.sup.1 is phenyl or phenyl substituted by at least one alkyl or alkoxy group. A mole ratio of aluminum to (R.sup.1O).sub.xM is from 0.1:1 to 1:1. The catalyst is present at a level of at least 200 ppm based on weight of aluminum.

  8. Hydrogen storage properties of metallic hydrides

    International Nuclear Information System (INIS)

    Latroche, M.; Percheron-Guegan, A.

    2005-01-01

    Nowadays, energy needs are mainly covered by fossil energies leading to pollutant emissions mostly responsible for global warming. Among the different possible solutions for greenhouse effect reduction, hydrogen has been proposed for energy transportation. Indeed, H 2 can be seen as a clean and efficient energy carrier. However, beside the difficulties related to hydrogen production, efficient high capacity storage means are still to be developed. Many metals and alloys are able to store large amounts of hydrogen. This latter solution is of interest in terms of safety, global yield and long term storage. However, to be suitable for applications, such compounds must present high capacity, good reversibility, fast reactivity and sustainability. In this paper, we will review the structural and thermodynamic properties of metallic hydrides. (authors)

  9. Boron hydride analogues of the fullerenes

    International Nuclear Information System (INIS)

    Quong, A.A.; Pederson, M.R.; Broughton, J.Q.

    1994-01-01

    The BH moiety is isoelectronic with C. We have studied the stability of the (BH) 60 analogue of the C 60 fullerene as well as the dual-structure (BH) 32 icosahedron, both of them being putative structures, by performing local-density-functional electronic calculations. To aid in our analysis, we have also studied other homologues of these systems. We find that the latter, i.e., the dual structure, is the more stable although the former is as stable as one of the latter's lower homologues. Boron hydrides, it seems, naturally form the dual structures used in algorithmic optimization of complex fullerene systems. Fully relaxed geometries are reported as well as electron affinities and effective Hubbard U parameters. These systems form very stable anions and we conclude that a search for BH analogues of the C 60 alkali-metal supeconductors might prove very fruitful

  10. Barium sulfate aspiration: Severe chemical pneumonia induced by a massive reflux of contrast medium during small bowel barium enema.

    Science.gov (United States)

    Zhang, Lin; Yang, Yi; Zhang, Ji; Zhou, Xiaowei; Dong, Hongmei; Zhou, Yiwu

    2015-08-01

    Barium contrast radiography is a conventional procedure aimed at revealing lesions of the alimentary tract using barium sulfate on X-ray irradiation. Although it is widely used in clinics, adverse effects and complications are observed, such as anaphylaxis, granuloma, fecalithes, abdomen-leaking, embolism, bacterial contamination, and aspiration. We report a case of death due to a massive barium sulfate aspiration resulted from an air-barium double contrast enema radiography. A 25-year-old female patient was hospitalized with symptoms of abdominal distention, nausea, vomiting and diarrhea for three days. A progressive respiratory distress presented only 1h after a small bowel air-barium double contrast enema. The patient died 11h later. The result of autopsy revealed the cause of death to be severe chemical pneumonitis induced by gastric fluid which was aspirated into her lungs. Barium sulfate is generally recognized to be chemically inert for the respiratory system, but a mixture of barium sulfate with gastric contents is fatal. Here we intend to suggest that, when determining the potential cause of death, medical examiners should consider a patient's status quo as well as the possible adverse effects and complications caused by the barium sulfate preparation during gastrointestinal radiography. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  11. The progress of nanocrystalline hydride electrode materials

    International Nuclear Information System (INIS)

    Jurczyk, M.

    2004-01-01

    This paper reviews research at the Institute of Materials Science and Engineering, Poznan University of Technology, on the synthesis of nanocrystalline hydride electrode materials. Nanocrystalline materials have been synthesized by mechanical alloying (MA) followed by annealing. Examples of the materials include TiFe - , ZrV 2- , LaNi 5 and Mg 2 Ni-type phases. Details on the process used and the enhancement of properties due to the nanoscale structures are presented. The synthesized alloys were used as negative electrode materials for Ni-MH battery. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. For example, it was found that the respective replacement of Fe in TiFe by Ni and/or by Cr, Co, Mo improved not only the discharge capacity but also the cycle life of these electrodes. The hydrogen storage properties of nanocrystalline ZrV 2 - and LaNi 5 -type powders prepared by mechanical alloying and annealing show no big difference with those of melt casting (polycrystalline) alloys. On the other hand, a partial substitution of Mg by Mn or Al in Mg 2 Ni alloy leads to an increase in discharge capacity, at room temperature. Furthermore, the effect of the nickel and graphite coating on the structure of some nanocrystalline alloys and the electrodes characteristics were investigated. In the case of Mg 2 Ni-type alloy mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials. The combination of a nanocrystalline TiFe - , ZrV 2 - and LaNi 5 -type hydride electrodes and a nickel positive electrode to form a Ni-MH battery, has been successful. (authors)

  12. 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.

  13. Precipitation of hydrides in high purity niobium after different treatments

    Energy Technology Data Exchange (ETDEWEB)

    Barkov, F.; Romanenko, A.; Trenikhina, Y.; Grassellino, A.

    2013-01-01

    Precipitation of lossy non-superconducting niobium hydrides represents a known problem for high purity niobium in superconducting applications. Using cryogenic optical and laser confocal scanning microscopy we have directly observed surface precipitation and evolution of niobium hydrides in samples after different treatments used for superconducting RF cavities for particle acceleration. Precipitation is shown to occur throughout the sample volume, and the growth of hydrides is well described by the fast diffusion-controlled process in which almost all hydrogen is precipitated at $T=140$~K within $\\sim30$~min. 120$^{\\circ}$C baking and mechanical deformation are found to affect hydride precipitation through their influence on the number of nucleation and trapping centers.

  14. Artificial exomuscle investigations for applications-metal hydride

    International Nuclear Information System (INIS)

    Crevier, Marie-Charlotte; Richard, Martin; Rittenhouse, D Matheson; Roy, Pierre-Olivier; Bedard, Stephane

    2007-01-01

    In pursuing the development of bionic devices, Victhom identified a need for technologies that could replace current motorized systems and be better integrated into the human body motion. The actuators used to obtain large displacements are noisy, heavy, and do not adequately reproduce human muscle behavior. Subsequently, a project at Victhom was devoted to the development of active materials to obtain an artificial exomuscle actuator. An exhaustive literature review was done at Victhom to identify promising active materials for the development of artificial muscles. According to this review, metal hydrides were identified as a promising technology for artificial muscle development. Victhom's investigations focused on determining metal hydride actuator potential in the context of bionics technology. Based on metal hydride properties and artificial muscle requirements such as force, displacement and rise time, an exomuscle was built. In addition, a finite element model, including heat and mass transfer in the metal hydride, was developed and implemented in FEMLAB software. (review article)

  15. A mechanistic approach to develop the secondary hydriding criteria

    International Nuclear Information System (INIS)

    Evdokimov, I.; Sorokin, A.; Kanukova, V.; Likhanskii, V.

    2009-01-01

    Reliable criteria of secondary hydriding failures are important to assure safe operation of nuclear fuel in LWR power units. The present paper reviews available data on massive hydriding of Zirconium claddings covering out-of-pile studies and in-pile tests in research reactors. Analyses of these experimental data give evidence that threshold conditions leading to the onset of massive hydriding are drastically changed under irradiation. The changes are caused mainly by irradiation damage of oxygen sublattice in ZrO 2 by fission fragments leaving the periphery of fuel pellets. The tests in research reactors provide a basis to develop a parametric dependency which relates the threshold of massive hydriding to composition of steam-hydrogen mixture, irradiation dose rate and temperature

  16. DETERMINATION OF METAL HYDRIDE SYSTEMS CHARACTERISTICS WHILE HEATING

    Directory of Open Access Journals (Sweden)

    Yu. Kluchka

    2012-01-01

    Full Text Available Experimental dependence of the pressure of hydrogen in the hydride cartridge when it is heated is obtained. Experimental data prove the theoretical values with an accuracy of ≈ 6%.

  17. High-pressure synthesis of noble metal hydrides.

    Science.gov (United States)

    Donnerer, Christian; Scheler, Thomas; Gregoryanz, Eugene

    2013-04-07

    The formation of hydride phases in the noble metals copper, silver, and gold was investigated by in situ x-ray diffraction at high hydrogen pressures. In the case of copper, a novel hexagonal hydride phase, Cu2H, was synthesised at pressures above 18.6 GPa. This compound exhibits an anti-CdI2-type structure, where hydrogen atoms occupy every second layer of octahedral interstitial sites. In contrast to chemically produced CuH, this phase does not show a change in compressibility compared to pure copper. Furthermore, repeated compression (after decomposition of Cu2H) led to the formation of cubic copper hydride at 12.5 GPa, a phenomenon attributed to an alteration of the microstructure during dehydrogenation. No hydrides of silver (up to 87 GPa) or gold (up to 113 GPa) were found at both room and high temperatures.

  18. Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

    Directory of Open Access Journals (Sweden)

    Kasper T. Møller

    2017-10-01

    Full Text Available Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted how complex metal hydrides may act in an integrated setup with a fuel cell. This review focuses on the unique properties of light element complex metal hydrides mainly based on boron, nitrogen and aluminum, e.g., metal borohydrides and metal alanates. Our hope is that this review can provide new inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy.

  19. Process for massively hydriding zirconium--uranium fuel elements

    Science.gov (United States)

    Katz, N.H.

    1973-12-01

    A method is described of hydriding uranium-zirconium alloy by heating the alloy in a vacuum, introducing hydrogen and maintaining an elevated temperature until occurrence of the beta--delta phase transformation and isobarically cooling the composition. (Official Gazette)

  20. NANOSCALE BARIUM HYDROSILICATES: CHOOSING THE SYNTHESIS TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    GRISHINA Anna Nikolaevna

    2013-08-01

    Full Text Available Cement concretes are the most used materials in modern civil engineering. Due to that such materials draw great attention both in the Russian Federation and abroad. The possibility to enhance the manufacturability and operational properties of concretes results in significant reduction of overall operating costs. Many enhancement methods have been elaborated. Among them there is one based on introduction of calcium hydrosilicates into construction composition. The authors set up a hypothesis that similarity between properties and structures of different hydrosilicates (for example, alkaline earth metals and metals of the second group will provide similar increased operational characteristics. The specialists of Research and Educational Center «Nanotechnology» are developing cement composites nanomodification methods which include introduction of nanodimensional barium hydrosilicates particles. The synthesis of barium hydrosilicates particles can be done with the use of many technologies, different by energy consumption or performing complexity. Taking into account both these factors, one can assume that low-temperature sol-gel synthesis from diluted water solutions is the proper technology. The present paper shows that this assumption is correct. The selection of certain technology is made by the means of multiobjective optimization, which is in turn is performed by the means of linear scalarization. This method, while not always giving the Pareto optimal solutions, can be easily implemented. The particle size distribution is taken into consideration during selection of objectives and weights. It is shown that selected technology allows manufacturing nanoparticles with median size about 30 nm.

  1. The Novel Formation of Barium Titanate Nanodendrites

    Directory of Open Access Journals (Sweden)

    Chien-Jung Huang

    2014-01-01

    Full Text Available The barium titanate (BaTiO3 nanoparticles with novel dendrite-like structures have been successfully fabricated via a simple coprecipitation method, the so-called BaTiO3 nanodendrites (BTNDs. This method was remarkable, fast, simple, and scalable. The growth solution is prepared by barium chloride (BaCl2, titanium tetrachloride (TiCl4, and oxalic acid. The shape and size of BaTiO3 depend on the amount of added BaCl2 solvent. To investigate the influence of amount of BaCl2 on BTNDs, the amount of BaCl2 was varied in the range from 3 to 6 mL. The role of BaCl2 is found to have remarkable influence on the morphology, crystallite size, and formation of dendrite-like structures. The thickness and length of the central stem of BTND were ~300 nm and ~20 μm, respectively. The branchings were found to occur at irregular intervals along the main stem. Besides, the formation mechanism of BTND is proposed and discussed.

  2. Three barium diphosphonates with 3-D structures

    Science.gov (United States)

    Tuikka, Matti; Haukka, Matti; Ahlgrén, Markku

    2007-06-01

    The gel crystallization method was exploited in this work in order to study the 3-D solid state structures of barium diphosphonates. This technique proved to be an effective tool for the growth of single crystals of diphosphonates for structure analysis. By using this approach, three barium diphosphonates, Ba[HO 3P(CH 2) 2PO 3H] ( 1), Ba 2[O 3P(CH 2) 3PO 3]·3H 2O ( 2) and Ba[HO 3P(CH 2) 4PO 3H] ( 3), with different three dimensional structures, were synthesized and characterized. The structures of compounds 1 and 2 were determined by single crystal X-ray diffraction and the structure of 3 by the powder diffraction method. In the structure of 1, the diphosphonate ligand is completely surrounded by the Ba atoms, which is an unusual arrangement in a diphosphonate system. The structures of 2 and 3 are more conventional. They are organized in typical pillared layers in which the separation of the layers can be adjusted by varying the length of the hydrocarbon chain.

  3. Reactions of zinc hydride and magnesium hydride with pyridine; synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes

    NARCIS (Netherlands)

    Koning, A.J. de; Boersma, J.; Kerk, G.J.M. van der

    1980-01-01

    The synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes are described. Zinc hydride and magnesium hydride dissolve in and react with pyridine, and the reaction has been studied in detail in the case of zinc hydride. Evaporation of the solvent after 1–2 hours at 0°C

  4. Modelling of fuel rod hydriding failures in water reactors

    International Nuclear Information System (INIS)

    Afanas'eva, E.Yu.; Evdokimov, I.A.; Khoruzhij, O.V.; Likhanskij, V.V.; Sorokin, A.A.

    2003-01-01

    Mechanistic models which were developed to describe primary hydriding phenomena in claddings of initially intact rods with residual moisture are described. The models include the following key processes: fuel rod thermal behavior, UO 2 fuel oxidation in steam-hydrogen atmosphere under irradiation, hydrogen diffusion in zirconium and in the hydride, growth of the hydride phase. Fuel rod thermomechanical behavior is calculated by using RTOP integral fuel code. An oxidation model represents the effects of temperature dynamics and temperature profile along fuel axis and radius on fuel oxidation as well as on hydrogen accumulation inside the fuel rod. Along with ordinary thermal dissociation of water molecules, the oxidation model also addresses radiolysis of the steam-hydrogen mixture due to fission fragments. The present radiolysis model takes into account the effects of the gas mixture composition, temperature and pressure. A new model of cladding hydriding is proposed in which calculation of the massive hydride growth is performed in 2-D geometry. Hydrogen transport in zirconium cladding is modeled with account for thermodiffusion. The RTOP code comprising the models developed allows us to calculate different scenarios of hydriding rod failures under given operation conditions. Test calculations were carried out and compared to available data. It is shown that there are threshold values of initial steam content inside the intact fuel rod which lead to the possibility of through-cladding hydride growth and formation of the primary defect. The threshold values depend on the oxidation state of the cladding inner surface, linear power profile in the fuel rod, fuel rod geometry, cladding temperature conditions and hydrogen diffusivities in zirconium and zirconium hydride

  5. Electronic structure and optical properties of lightweight metal hydrides

    NARCIS (Netherlands)

    van Setten, M.J.; Popa, V.A.; Popa, V.A.; de Wijs, G.A.; Brocks, G.

    2007-01-01

    We study the dielectric functions of the series of simple hydrides LiH, NaH, MgH2, and AlH3, and of the complex hydrides Li3AlH6, Na3AlH6, LiAlH4, NaAlH4, and Mg(AlH4)2, using first-principles density-functional theory and GW calculations. All compounds are large gap insulators with GW

  6. Solving crystal structures of metal and chemical hydrides

    OpenAIRE

    Cerny, Radovan

    2008-01-01

    The methods of structural characterization of metal and chemical hydrides are reviewed. The existing difficulties and problems are outlined and possible solutions presented. It is shown that powder diffraction, and especially the Direct Space Method, is essential component of hydride research. Crystal structures containing as many as 55 independent atoms (including hydrogen) have been fully characterized using powder diffraction. This is of great importance, because rapid collection of powder...

  7. The Production of Uranium Metal by Metal Hydrides Incorporated

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, P. P.

    1943-01-01

    Metal Hydrides Incorporated was a pioneer in the production of uranium metal on a commercial scale and supplied it to all the laboratories interested in the original research, before other methods for its production were developed. Metal Hydrides Inc. supplied the major part of the metal for the construction of the first experimental pile which, on December 2, 1942, demonstrated the feasibility of the self-sustaining chain reaction and the release of atomic energy.

  8. The use of metal hydrides in fuel cell applications

    Directory of Open Access Journals (Sweden)

    Mykhaylo V. Lototskyy

    2017-02-01

    Full Text Available This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field, as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells. The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally, the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.

  9. U-8 wt %Mo and 7 wt %Mo alloys powder obtained by an hydride-de hydride process

    International Nuclear Information System (INIS)

    Balart, Silvia N.; Bruzzoni, Pablo; Granovsky, Marta S.; Gribaudo, Luis M. J.; Hermida, Jorge D.; Ovejero, Jose; Rubiolo, Gerardo H.; Vicente, Eduardo E.

    2000-01-01

    Uranium-molybdenum alloys are been tested as a component in high-density LEU dispersion fuels with very good performances. These alloys need to be transformed to powder due to the manufacturing requirements of the fuels. One method to convert ductile alloys into powder is the hydride-de hydride process, which takes advantage of the ability of the U-α phase to transform to UH 3 : a brittle and relatively low-density compound. U-Mo alloys around 7 and 8 wt % Mo were melted and heat treated at different temperature ranges in order to partially convert γ -phase to α -phase. Subsequent hydriding transforms this α -phase to UH 3 . The volume change associated to the hydride formation embrittled the material which ends up in a powdered alloy. Results of the optical metallography, scanning electron microscopy, X-ray diffraction during different steps of the process are shown. (author)

  10. Radiation doses to patients undergoing barium meal and barium enema examinations

    International Nuclear Information System (INIS)

    Delichas, M. G.; Hatziioannou, K.; Papanastassiou, E.; Albanopoulou, P.; Chatzi, E.; Sioundas, A.; Psarrakos, K.

    2004-01-01

    The radiation doses received by patients during 41 barium meal (BM) and 42 barium enema (BE) examinations in two Greek hospitals are presented. Radiation dose was measured in terms of the dose area product (DAP). The effective dose and doses to certain organs were estimated using the ODS-60 software. Mean total DAP values were found to be 25 ± 11 Gy cm 2 for BM and 60 ± 35 Gy cm 2 for BE examinations, whereas the estimated mean values of effective dose were 8.6 ± 4.0 and 24 ± 16 mSv respectively. DAP to effective dose conversion coefficients were estimated to be 0.34 mSv per Gy cm 2 for BM and 0.41 mSv per Gy cm 2 for BE. (authors)

  11. Fullerene hydride - A potential hydrogen storage material

    International Nuclear Information System (INIS)

    Nai Xing Wang; Jun Ping Zhang; An Guang Yu; Yun Xu Yang; Wu Wei Wang; Rui long Sheng; Jia Zhao

    2005-01-01

    Hydrogen, as a clean, convenient, versatile fuel source, is considered to be an ideal energy carrier in the foreseeable future. Hydrogen storage must be solved in using of hydrogen energy. To date, much effort has been put into storage of hydrogen including physical storage via compression or liquefaction, chemical storage in hydrogen carriers, metal hydrides and gas-on-solid adsorption. But no one satisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. C 60 H 36 , firstly synthesized by the method of the Birch reduction, was loaded with 4.8 wt% hydrogen indicating [60]fullerene might be as a potential hydrogen storage material. If a 100% conversion of C 60 H 36 is achieved, 18 moles of H 2 gas would be liberated from each mole of fullerene hydride. Pure C 60 H 36 is very stable below 500 C under nitrogen atmosphere and it releases hydrogen accompanying by other hydrocarbons under high temperature. But C 60 H 36 can be decomposed to generate H 2 under effective catalyst. We have reported that hydrogen can be produced catalytically from C 60 H 36 by Vasks's compound (IrCl(CO)(PPh 3 ) 2 ) under mild conditions. (RhCl(CO)(PPh 3 ) 2 ) having similar structure to (IrCl(CO)(PPh 3 ) 2 ), was also examined for thermal dehydrogenation of C 60 H 36 ; but it showed low catalytic activity. To search better catalyst, palladium carbon (Pd/C) and platinum carbon (Pt/C) catalysts, which were known for catalytic hydrogenation of aromatic compounds, were tried and good results were obtained. A very big peak of hydrogen appeared at δ=5.2 ppm in 1 H NMR spectrum based on Evans'work (fig 1) at 100 C over a Pd/C catalyst for 16 hours. It is shown that hydrogen can be produced from C 60 H 36 using a catalytic amount of Pd/C. Comparing with Pd/C, Pt/C catalyst showed lower activity. The high cost and limited availability of Vaska's compounds, Pd and Pt make it advantageous to develop less expensive catalysts for our process based on

  12. High growth rate hydride vapor phase epitaxy at low temperature through use of uncracked hydrides

    Science.gov (United States)

    Schulte, Kevin L.; Braun, Anna; Simon, John; Ptak, Aaron J.

    2018-01-01

    We demonstrate hydride vapor phase epitaxy (HVPE) of GaAs with unusually high growth rates (RG) at low temperature and atmospheric pressure by employing a hydride-enhanced growth mechanism. Under traditional HVPE growth conditions that involve growth from Asx species, RG exhibits a strong temperature dependence due to slow kinetics at the surface, and growth temperatures >750 °C are required to obtain RG > 60 μm/h. We demonstrate that when the group V element reaches the surface in a hydride, the kinetic barrier is dramatically reduced and surface kinetics no longer limit RG. In this regime, RG is dependent on mass transport of uncracked AsH3 to the surface. By controlling the AsH3 velocity and temperature profile of the reactor, which both affect the degree of AsH3 decomposition, we demonstrate tuning of RG. We achieve RG above 60 μm/h at temperatures as low as 560 °C and up to 110 μm/h at 650 °C. We incorporate high-RG GaAs into solar cell devices to verify that the electronic quality does not deteriorate as RG is increased. The open circuit voltage (VOC), which is a strong function of non-radiative recombination in the bulk material, exhibits negligible variance in a series of devices grown at 650 °C with RG = 55-110 μm/h. The implications of low temperature growth for the formation of complex heterostructure devices by HVPE are discussed.

  13. Isolation of a mixed valence diiron hydride: evidence for a spectator hydride in hydrogen evolution catalysis.

    Science.gov (United States)

    Wang, Wenguang; Nilges, Mark J; Rauchfuss, Thomas B; Stein, Matthias

    2013-03-06

    The mixed-valence diiron hydrido complex (μ-H)Fe2(pdt)(CO)2(dppv)2 ([H1](0), where pdt =1,3-propanedithiolate and dppv = cis-1,2-C2H2(PPh2)2), was generated by reduction of the differous hydride [H1](+) using decamethylcobaltocene. Crystallographic analysis shows that [H1](0) retains the stereochemistry of its precursor, where one dppv ligand spans two basal sites and the other spans apical and basal positions. The Fe---Fe bond elongates to 2.80 from 2.66 Å, but the Fe-P bonds only change subtly. Although the Fe-H distances are indistinguishable in the precursor, they differ by 0.2 Å in [H1](0). The X-band electron paramagnetic resonance (EPR) spectrum reveals the presence of two stereoisomers, the one characterized crystallographically and a contribution of about 10% from a second symmetrical (sym) isomer wherein both dppv ligands occupy apical-basal sites. The unsymmetrical (unsym) arrangement of the dppv ligands is reflected in the values of A((31)P), which range from 31 MHz for the basal phosphines to 284 MHz for the apical phosphine. Density functional theory calculations were employed to rationalize the electronic structure of [H1](0) and to facilitate spectral simulation and assignment of EPR parameters including (1)H and (31)P hyperfine couplings. The EPR spectra of [H1](0) and [D1](0) demonstrate that the singly occupied molecular orbital is primarily localized on the Fe center with the longer bond to H, that is, Fe(II)-H···Fe(I). The coupling to the hydride is A((1)H) = 55 and 74 MHz for unsym- amd sym-[H1](0), respectively. Treatment of [H1](0) with H(+) gives 0.5 equiv of H2 and [H1](+). Reduction of D(+) affords D2, leaving the hydride ligand intact. These experiments demonstrate that the bridging hydride ligand in this complex is a spectator in the hydrogen evolution reaction.

  14. Chemical Hydride Slurry for Hydrogen Production and Storage

    Energy Technology Data Exchange (ETDEWEB)

    McClaine, Andrew W

    2008-09-30

    The purpose of this project was to investigate and evaluate the attractiveness of using a magnesium chemical hydride slurry as a hydrogen storage, delivery, and production medium for automobiles. To fully evaluate the potential for magnesium hydride slurry to act as a carrier of hydrogen, potential slurry compositions, potential hydrogen release techniques, and the processes (and their costs) that will be used to recycle the byproducts back to a high hydrogen content slurry were evaluated. A 75% MgH2 slurry was demonstrated, which was just short of the 76% goal. This slurry is pumpable and storable for months at a time at room temperature and pressure conditions and it has the consistency of paint. Two techniques were demonstrated for reacting the slurry with water to release hydrogen. The first technique was a continuous mixing process that was tested for several hours at a time and demonstrated operation without external heat addition. Further work will be required to reduce this design to a reliable, robust system. The second technique was a semi-continuous process. It was demonstrated on a 2 kWh scale. This system operated continuously and reliably for hours at a time, including starts and stops. This process could be readily reduced to practice for commercial applications. The processes and costs associated with recycling the byproducts of the water/slurry reaction were also evaluated. This included recovering and recycling the oils of the slurry, reforming the magnesium hydroxide and magnesium oxide byproduct to magnesium metal, hydriding the magnesium metal with hydrogen to form magnesium hydride, and preparing the slurry. We found that the SOM process, under development by Boston University, offers the lowest cost alternative for producing and recycling the slurry. Using the H2A framework, a total cost of production, delivery, and distribution of $4.50/kg of hydrogen delivered or $4.50/gge was determined. Experiments performed at Boston

  15. Large Flexoelectric Anisotropy in Paraelectric Barium Titanate.

    Science.gov (United States)

    Narvaez, Jackeline; Saremi, Sahar; Hong, Jiawang; Stengel, Massimiliano; Catalan, Gustau

    2015-07-17

    The bending-induced polarization of barium titanate single crystals has been measured with an aim to elucidate the origin of the large difference between theoretically predicted and experimentally measured flexoelectricity in this material. The results indicate that part of the difference is due to polar regions (short-range order) that exist above T(C) and up to T*≈200-225 °C. Above T*, however, the flexovoltage coefficient still shows an unexpectedly large anisotropy for a cubic material, with (001)-oriented crystals displaying 10 times more flexoelectricity than (111)-oriented crystals. Theoretical analysis shows that this anisotropy cannot be a bulk property, and we therefore interpret it as indirect evidence for the theoretically predicted but experimentally elusive contribution of surface piezoelectricity to macroscopic bending-induced polarization.

  16. Large Flexoelectric Anisotropy in Paraelectric Barium Titanate

    Science.gov (United States)

    Narvaez, Jackeline; Saremi, Sahar; Hong, Jiawang; Stengel, Massimiliano; Catalan, Gustau

    2015-07-01

    The bending-induced polarization of barium titanate single crystals has been measured with an aim to elucidate the origin of the large difference between theoretically predicted and experimentally measured flexoelectricity in this material. The results indicate that part of the difference is due to polar regions (short-range order) that exist above TC and up to T*≈2 00 - 2 2 5 °C . Above T* , however, the flexovoltage coefficient still shows an unexpectedly large anisotropy for a cubic material, with (001)-oriented crystals displaying 10 times more flexoelectricity than (111)-oriented crystals. Theoretical analysis shows that this anisotropy cannot be a bulk property, and we therefore interpret it as indirect evidence for the theoretically predicted but experimentally elusive contribution of surface piezoelectricity to macroscopic bending-induced polarization.

  17. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    degrees C and evidence was found for the solidification of the melt at 380-440 degrees C, i.e. simultaneously with the onset of decomposition. Between 400 degrees C and 520 degrees C (Ba(C4H9CO2)(2) decomposes in two main steps, first into BaCO3 with release of C4H9COC4H9 (5-nonanone), whereas final......The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  18. Solar Twins and the Barium Puzzle

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Arumalla B. S.; Lambert, David L., E-mail: bala@astro.as.utexas.edu [W.J. McDonald Observatory and Department of Astronomy, The University of Texas at Austin, Austin, TX 78712-1205 (United States)

    2017-08-20

    Several abundance analyses of Galactic open clusters (OCs) have shown a tendency for Ba but not for other heavy elements (La−Sm) to increase sharply with decreasing age such that Ba was claimed to reach [Ba/Fe] ≃ +0.6 in the youngest clusters (ages < 100 Myr) rising from [Ba/Fe] = 0.00 dex in solar-age clusters. Within the formulation of the s -process, the difficulty to replicate higher Ba abundance and normal La−Sm abundances in young clusters is known as the barium puzzle. Here, we investigate the barium puzzle using extremely high-resolution and high signal-to-noise spectra of 24 solar twins and measured the heavy elements Ba, La, Ce, Nd, and Sm with a precision of 0.03 dex. We demonstrate that the enhanced Ba ii relative to La−Sm seen among solar twins, stellar associations, and OCs at young ages (<100 Myr) is unrelated to aspects of stellar nucleosynthesis but has resulted from overestimation of Ba by standard methods of LTE abundance analysis in which the microturbulence derived from the Fe lines formed deep in the photosphere is insufficient to represent the true line broadening imposed on Ba ii lines by the upper photospheric layers from where the Ba ii lines emerge. Because the young stars have relatively active photospheres, Ba overabundances most likely result from the adoption of a too low value of microturbulence in the spectrum synthesis of the strong Ba ii lines but the change of microturbulence in the upper photosphere has only a minor affect on La−Sm abundances measured from the weak lines.

  19. Influence of uranium hydride oxidation on uranium metal behaviour

    International Nuclear Information System (INIS)

    Patel, N.; Hambley, D.; Clarke, S.A.; Simpson, K.

    2013-01-01

    This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

  20. Hydriding and neutron irradiation in zircaloy-4

    International Nuclear Information System (INIS)

    Ramos, Ruben Fortunato; Martin, Juan Ezequiel; Orellano, Pablo; Dorao, Carlos; Analia Soldati; Ghilarducci, Ada Albertina; Corso, Hugo Luis; Peretti, Hernan Americo; Bolcich, Juan Carlos

    2003-01-01

    The composition of Zircaloy-4 for nuclear applications is specified by the ASTM B350 Standard, that fixes the amount of alloying elements (Sn, Fe, Cr) and impurities (Ni, Hf, O, N, C, among others) to optimize good corrosion and mechanical behavior.The recycling of zircaloy-4 scrap and chips resulting from cladding tube fabrication is an interesting issue.However, changes in the final composition of the recycled material may occur due to contamination with tool pieces, stainless steel chips, turnings, etc. while scrap is stored and handled. Since the main components of the possible contaminants are Fe, Cr and Ni, it arises the interest in studying up to what limit the Fe, Ni and Cr contents could be exceeded beyond the standard specification without affecting significantly the alloy properties.Zircaloy-4 alloys elaborated with Fe, Cr and Ni additions and others of standard composition in use in nuclear plants are studied by tensile tests, SEM observations and EDS microanalysis.Some samples are tested in the initial condition and others after hydriding treatments and neutron irradiation in the RA6

  1. Study of the photovoltaic effect in thin film barium titanate

    Science.gov (United States)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1983-01-01

    The feasibility of making non-volatile digital memory devices of barium titanate, BaTiO3, that are integrated onto a silicon substrate with the required ferroelectric film produced by processing, compatible with silicon technology was examined.

  2. Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions

    International Nuclear Information System (INIS)

    Harris, Joe P.; Manship, Daniel R.; Wright, Timothy G.; Breckenridge, W. H.

    2014-01-01

    We study both the rare gas hydride anions, RG–H − (RG = He–Rn) and Group 2 (Group IIa) metal hydride anions, M IIa H − (M IIa = Be–Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be–He complex. While the RG–H − and Be–He species are weakly bound, we show that, as with the previously studied BeH − and MgH − species, the other M IIa H − species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns 2 ) and H − (1s 2 ). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the M IIa H − species than for RG–H − . Our analyses lead us to conclude that the stronger interaction in the case of the M IIa H − species arises from sp and spd hybridization, which allows electron density on the M IIa atom to move away from the incoming H −

  3. Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions.

    Science.gov (United States)

    Harris, Joe P; Manship, Daniel R; Breckenridge, W H; Wright, Timothy G

    2014-02-28

    We study both the rare gas hydride anions, RG-H(-) (RG = He-Rn) and Group 2 (Group IIa) metal hydride anions, MIIaH(-) (MIIa = Be-Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be-He complex. While the RG-H(-) and Be-He species are weakly bound, we show that, as with the previously studied BeH(-) and MgH(-) species, the other MIIaH(-) species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns(2)) and H(-)(1s(2)). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the MIIaH(-) species than for RG-H(-). Our analyses lead us to conclude that the stronger interaction in the case of the MIIaH(-) species arises from sp and spd hybridization, which allows electron density on the MIIa atom to move away from the incoming H(-).

  4. The Overview of The Electrical Properties of Barium Titanate

    OpenAIRE

    Burcu Ertuğ

    2013-01-01

    The perovskite family includes many titanates used in various electroceramic applications, for example, electronic, electro-optical, and electromechanical applications of ceramics. Barium titanate, perovskite structure, is a common ferroelectric material with a high dielectric constant, widely utilized to manufacture electronic components such as mutilayer capacitors (MLCs), PTC thermistors, piezoelectric transducers, and a variety of electro-optic devices. Pure barium titanate is an insulato...

  5. Mechanisms of hydrogen induced delayed cracking in hydride forming materials

    International Nuclear Information System (INIS)

    Dutton, R.; Nuttall, K.; Puls, M.P.; Simpson, L.A.

    1977-01-01

    Mechanisms which have been formulated to describe delayed hydrogen cracking in hydride-forming metals are reviewed and discussed. Particular emphasis is placed on the commercial alloy Zr--2.5% Nb (Cb) which is extensively used in nuclear reactor core components. A quantitative model for hydrogen cracking in this material is presented and compared with available experimental data. The kinetics of crack propagation are controlled by the growth of hydrides at the stressed crack tip by the diffusive ingress of hydrogen into this region. The driving force for the diffusion flux is provided by the local stress gradient which interacts with both hydrogen atoms in solution and hydrogen atoms being dissolved and reprecipitated at the crack tip. The model is developed using concepts of elastoplastic fracture mechanics. Stage I crack growth is controlled by hydrides growing in the elastic stress gradient, while Stage II is controlled by hydride growth in the plastic zone at the crack tip. Recent experimental observations are presented which indicate that the process occurs in an intermittent fashion; hydride clusters accumulate at the crack tip followed by unstable crack advance and subsequent crack arrest in repeated cycles

  6. Sodium-based hydrides for thermal energy applications

    Science.gov (United States)

    Sheppard, D. A.; Humphries, T. D.; Buckley, C. E.

    2016-04-01

    Concentrating solar-thermal power (CSP) with thermal energy storage (TES) represents an attractive alternative to conventional fossil fuels for base-load power generation. Sodium alanate (NaAlH4) is a well-known sodium-based complex metal hydride but, more recently, high-temperature sodium-based complex metal hydrides have been considered for TES. This review considers the current state of the art for NaH, NaMgH3- x F x , Na-based transition metal hydrides, NaBH4 and Na3AlH6 for TES and heat pumping applications. These metal hydrides have a number of advantages over other classes of heat storage materials such as high thermal energy storage capacity, low volume, relatively low cost and a wide range of operating temperatures (100 °C to more than 650 °C). Potential safety issues associated with the use of high-temperature sodium-based hydrides are also addressed.

  7. Cost-effectiveness of barium enemas performed by radiographers

    International Nuclear Information System (INIS)

    Brown, Lorraine; Desai, Sharad

    2002-01-01

    AIM: To assess the cost-effectiveness of barium enemas performed by radiographers compared to those performed by consultant radiologists. METHOD: Prospective study of 200 barium enemas carried out by a senior radiographer and a consultant radiologist. The sample was a consecutive sample of adult out-patients over a 3-month period, with no exclusion. The length of time of the enema and the numbers and grades of staff involved in the procedure were recorded. This was translated into staffing costs using the appropriate pay scales. RESULTS: The barium enemas performed by the superintendent radiographer were more cost-effective than those performed by the consultant radiologist (1406 pounds for 100 radiographer-performed barium enemas compared to 1787 pounds for 100 carried out by the consultant radiologist). CONCLUSION: In terms of staffing costs, radiographers performing barium enemas not only liberates radiologist time, it is also a cost-effective method of providing an out-patient barium enema service. Brown, L. and Desai, S. (2002)

  8. Study on the Use of Hydride Fuel in High-Performance Light Water Reactor Concept

    OpenAIRE

    Haileyesus Tsige-Tamirat; Luca Ammirabile

    2015-01-01

    Hydride fuels have features which could make their use attractive in future advanced power reactors. The potential benefit of use of hydride fuel in HPLWR without introducing significant modification in the current core design concept of the high-performance light water reactor (HPLWR) has been evaluated. Neutronics and thermal hydraulic analyses were performed for a single assembly model of HPLWR with oxide and hydride fuels. The hydride assembly shows higher moderation with softer neutron s...

  9. A study of advanced magnesium-based hydride and development of a metal hydride thermal battery system

    Science.gov (United States)

    Zhou, Chengshang

    Metal hydrides are a group of important materials known as energy carriers for renewable energy and thermal energy storage. A concept of thermal battery based on advanced metal hydrides is studied for heating and cooling of cabins in electric vehicles. The system utilizes a pair of thermodynamically matched metal hydrides as energy storage media. The hot hydride that is identified and developed is catalyzed MgH2 due to its high energy density and enhanced kinetics. TiV0.62Mn1.5, TiMn2, and LaNi5 alloys are selected as the matching cold hydride. A systematic experimental survey is carried out in this study to compare a wide range of additives including transitions metals, transition metal oxides, hydrides, intermetallic compounds, and carbon materials, with respect to their effects on dehydrogenation properties of MgH2. The results show that additives such as Ti and V-based metals, hydride, and certain intermetallic compounds have strong catalytic effects. Solid solution alloys of magnesium are exploited as a way to destabilize magnesium hydride thermodynamically. Various elements are alloyed with magnesium to form solid solutions, including indium and aluminum. Thermodynamic properties of the reactions between the magnesium solid solution alloys and hydrogen are investigated, showing that all the solid solution alloys that are investigated in this work have higher equilibrium hydrogen pressures than that of pure magnesium. Cyclic stability of catalyzed MgH2 is characterized and analyzed using a PCT Sievert-type apparatus. Three systems, including MgH2-TiH 2, MgH2-TiMn2, and MgH2-VTiCr, are examined. The hydrogenating and dehydrogenating kinetics at 300°C are stable after 100 cycles. However, the low temperature (25°C to 150°C) hydrogenation kinetics suffer a severe degradation during hydrogen cycling. Further experiments confirm that the low temperature kinetic degradation can be mainly related the extended hydrogenation-dehydrogenation reactions. Proof

  10. Comparison of Hydrogen Elimination from Molecular Zinc and Magnesium Hydride Clusters

    NARCIS (Netherlands)

    Intemann, J.; Sirsch, Peter; Harder, Sjoerd

    2014-01-01

    In analogy to the previously reported tetranuclear magnesium hydride cluster with a bridged dianionic bis-beta-diketiminate ligand, a related zinc hydride cluster has been prepared. The crystal structures of these magnesium and zinc hydride complexes are similar: the metal atoms are situated at the

  11. Use of triammonium salt of aurin tricarboxylic acid as risk mitigant for aluminum hydride

    Science.gov (United States)

    Cortes-Concepcion, Jose A.; Anton, Donald L.

    2017-08-08

    A process and a resulting product by process of an aluminum hydride which is modified with by physically combining in a ball milling process an aluminum hydride with a triammonium salt of aurin tricarboxylic acid. The resulting product is an aluminum hydride which is resistant to air, ambient moisture, and liquid water while maintaining useful hydrogen storage and release kinetics.

  12. Synthesis of highly active Mg-Based hydrides using hydriding combustion synthesis and NbF5 Additives

    DEFF Research Database (Denmark)

    Chourashiya, M. G.; Park, C. N.; Park, C. J.

    2012-01-01

    Superiority of the hydriding combustion (HC) technique over conventional metallurgical approach to the synthesis of cost-effective Mg based hydrides, which show promise as hydrogen storage materials, is well known. In the present research, we report further improvements in HC prepared Mg-based ma...... samples achieved the maximum absorption/desorption limits (5.3 wt.%) at as low as 100°C, underlining the possibility of the use of these materials in portable hydrogen storage devices.......Superiority of the hydriding combustion (HC) technique over conventional metallurgical approach to the synthesis of cost-effective Mg based hydrides, which show promise as hydrogen storage materials, is well known. In the present research, we report further improvements in HC prepared Mg......-based materials, achieved by optimizing the preparative parameters of HC and by catalytic addition. Mg90-Ni60-C40 composites prepared using optimized processing parameters were ball-milled with NbF5 (10 h) and characterized for their micro-structural and hydriding properties. The ball-milled/catalyzed powder...

  13. Anastomotic stenosis of the descending colon caused by barium granuloma formation following barium peritonitis: report of a case.

    Science.gov (United States)

    Kitajima, Toshihiro; Tomizawa, Kenji; Hanaoka, Yutaka; Toda, Shigeo; Matoba, Shuichiro; Kuroyanagi, Hiroya; Oota, Yasunori

    2014-11-01

    Anastomotic stricture reportedly often recurs following barium peritonitis, regardless of whether the anastomotic diameter is initially sufficient. However, the causes of repetitive stricture have not been clarified. We report a case that suggests the pathophysiology of recurrent anastomotic strictures following barium peritonitis. The patient was a 39-year-old Japanese man with idiopathic perforation of the descending colon after undergoing an upper gastrointestinal barium contrast study. After emergency peritoneal lavage and diverting colostomy, created using the perforated region, the patient recovered uneventfully and 3 months later, the colostomy was closed and the perforated colon was resected. However, 7 months after colostomy closure, abdominal distention gradually developed, and colonoscopy revealed an anastomotic stricture. The patient was referred to our hospital where he underwent resection of the anastomotic stricture. The surgical specimen exhibited barium granulomas not only in the subserosa of the entire specimen, but also in the submucosa and lamina propria localized in the anastomotic site. These findings suggest that barium was embedded in the submucosa and lamina propria with manipulation of the stapled anastomosis and that the barium trapped in the anastomotic site caused persistent inflammation, resulting in an anastomotic stricture.

  14. Hydrides and deuterides of lithium and sodium. Pt. 1

    International Nuclear Information System (INIS)

    Haque, E.

    1990-01-01

    An interionic potential model is developed for lighter and heavier alkali hydrides and deuterides. The method uses a combination of theoretical techniques, empirical fit, and a few plausible assumptions. An assessment of the derived potentials is made by calculating the lattice statics and dynamics of the crystals and by comparing both with experiment (where available) and with other calculations. The potentials are found to describe the elastic and dielectric properties reasonably well. The phonon dispersion curves of hydride and deuteride of sodium are compared with the calculations of Dyck and Jex based on force constant model approach and the results are discussed. The need for further experiments on heavier hydrides and deuterides is stressed. (author)

  15. Research in Nickel/Metal Hydride Batteries 2017

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2018-02-01

    Full Text Available Continuing from a special issue in Batteries in 2016, nineteen new papers focusing on recent research activities in the field of nickel/metal hydride (Ni/MH batteries have been selected for the 2017 Special Issue of Ni/MH Batteries. These papers summarize the international joint-efforts in Ni/MH battery research from BASF, Wayne State University, Michigan State University, FDK Corp. (Japan, Institute for Energy Technology (Norway, Central South University (China, University of Science and Technology Beijing (China, Zhengzhou University of Light Industry (China, Inner Mongolia University of Science and Technology (China, Shenzhen Highpower (China, and University of the Witwatersrand (South Africa from 2016–2017 through reviews of AB2 metal hydride alloys, Chinese and EU Patent Applications, as well as descriptions of research results in metal hydride alloys, nickel hydroxide, electrolyte, and new cell type, comparison work, and projections of future works.

  16. High-Spin Cobalt Hydrides for Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Patrick L. [Univ. of Rochester, NY (United States)

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  17. The efficacy of steroids for postoperative persistent inflammatory reaction in a patient with barium peritonitis: A case report

    Directory of Open Access Journals (Sweden)

    Hirofumi Kojima

    2017-01-01

    Conclusion: Residual barium in the intraperitoneal cavity causes persistent inflammatory reaction in patients with barium peritonitis. The use of steroids is effective for postoperative persistent inflammation due to the residual barium.

  18. Biokinetics and effects of barium sulfate nanoparticles.

    Science.gov (United States)

    Konduru, Nagarjun; Keller, Jana; Ma-Hock, Lan; Gröters, Sibylle; Landsiedel, Robert; Donaghey, Thomas C; Brain, Joseph D; Wohlleben, Wendel; Molina, Ramon M

    2014-10-21

    Nanoparticulate barium sulfate has potential novel applications and wide use in the polymer and paint industries. A short-term inhalation study on barium sulfate nanoparticles (BaSO₄ NPs) was previously published [Part Fibre Toxicol 11:16, 2014]. We performed comprehensive biokinetic studies of ¹³¹BaSO₄ NPs administered via different routes and of acute and subchronic pulmonary responses to instilled or inhaled BaSO₄ in rats. We compared the tissue distribution of ¹³¹Ba over 28 days after intratracheal (IT) instillation, and over 7 days after gavage and intravenous (IV) injection of ¹³¹BaSO₄. Rats were exposed to 50 mg/m³ BaSO₄ aerosol for 4 or 13 weeks (6 h/day, 5 consecutive days/week), and then gross and histopathologic, blood and bronchoalveolar lavage (BAL) fluid analyses were performed. BAL fluid from instilled rats was also analyzed. Inhaled BaSO₄ NPs showed no toxicity after 4-week exposure, but a slight neutrophil increase in BAL after 13-week exposure was observed. Lung burden of inhaled BaSO₄ NPs after 4-week exposure (0.84 ± 0.18 mg/lung) decreased by 95% over 34 days. Instilled BaSO₄ NPs caused dose-dependent inflammatory responses in the lungs. Instilled BaSO₄ NPs (0.28 mg/lung) was cleared with a half-life of ≈ 9.6 days. Translocated ¹³¹Ba from the lungs was predominantly found in the bone (29%). Only 0.15% of gavaged dose was detected in all organs at 7 days. IV-injected ¹³¹BaSO₄ NPs were predominantly localized in the liver, spleen, lungs and bone at 2 hours, but redistributed from the liver to bone over time. Fecal excretion was the dominant elimination pathway for all three routes of exposure. Pulmonary exposure to instilled BaSO₄ NPs caused dose-dependent lung injury and inflammation. Four-week and 13-week inhalation exposures to a high concentration (50 mg/m³) of BaSO₄ NPs elicited minimal pulmonary response and no systemic effects. Instilled and inhaled BaSO₄ NPs were cleared quickly yet

  19. Complex metal hydrides for hydrogen, thermal and electrochemical energy storage

    DEFF Research Database (Denmark)

    Møller, Kasper T.; Sheppard, Drew; Ravnsbæk, Dorthe B.

    2017-01-01

    Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage...... field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted...... inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy....

  20. Microcapsulated rare earth - nickel hydride-forming materials

    International Nuclear Information System (INIS)

    Ishikawa, H.; Oguro, K.; Kato, A.; Suzuki, H.; Ishii, E.

    1985-01-01

    Fine particles of hydride-forming alloys such as LaNi/sub 5/ and MmNi/sub 4.5/Mn/sub 0.5/ (MM : mischmetal) were coated with metallic copper thin layer by chemical plating method. Hydrogen storage capacities of alloys were not appreciably affected by the plating treatment. The capsulated alloy powders were easily pressed into pellets. The pellets obtained had high thermal conductivity and porosity enough to permeate hydrogen, leading to fast reaction kinetics. These were able to withstand more than 5,000 repeated hydriding-dehydriding cycles without disintegrating

  1. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, B{sub x}Al{sub y}H{sub z}{sup −}, were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  2. Photoelectron spectroscopy of boron aluminum hydride cluster anions.

    Science.gov (United States)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H; Li, Xiang; Kiran, Boggavarapu; Kandalam, Anil K

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, BxAlyHz(-), were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  3. Hydriding and dehydriding properties of CaSi

    International Nuclear Information System (INIS)

    Aoki, Masakazu; Ohba, Nobuko; Noritake, Tatsuo; Towata, Shin-ichi

    2005-01-01

    The hydriding and dehydriding properties of CaSi were investigated both theoretically and experimentally. First-principles calculations suggested that CaSiH n is thermodynamically stable. Experimentally, the p -c isotherms clearly demonstrated plateau pressures in a temperature range of 473-573 K and the maximum hydrogen content was 1.9 weight % (wt.%) under a hydrogen pressure of 9 MPa at 473 K. The structure of CaSiH n is different from those of ZrNi hydrides, although CaSi has the CrB-type structure as well as ZrNi

  4. Research on secondary hydriding for advanced nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. S.; Kim, S. K. et al. [Hanyang Univ, Seoul (Korea)

    2000-04-01

    First, hydriding kinetics of zirconium alloys are derived as follows: Zircaloy-2 : 1.1X10{sup 7} exp(-20,800/RT), Zircaloy-4 : 6.9X10{sup 7} exp(-23,800/RT), ZIRLO{sup TM} : 1.5X10{sup 6} exp(-18,000/RT) and it is found that it is a linear kinetics. Second, H{sub 2}/H{sub 2}O-ratio-controlling experiments are performed as a function of the ratios, 10{sup 7}, 10{sup 5}. and 10{sup 3} in order to examine the oxidation enhancement under the competing environment of oxidation and hydriding. The results show that under the mixture environment hydriding reaction takes place initially, then reaction turn into oxidation with the growing oxide, and finally turn back into hydriding reaction because of oxide breakage. It is confirmed that the oxidation in the second stage is greatly enhanced due to hydride precipitation. Third, micro-structural analysis is carried out by using SEM/TEM to see the roles of the oxide in the massive hydriding process. It turns out that micro-structural changes of the oxide takes place at the beginning of the massive hydriding. Fourth experiments are carried out both in the pre-transition (at 370 deg C for 72 hours) and in the post-transition regime (at 700 deg C for 210 minutes) to see the pressure effects on the oxidation kinetics. Through this investigation, it is revealed that under 15MPa steam pressure the oxidation is enhanced by 50% in the pre-transition and by 150% in the post-transition regime, respectively. Last, the two stage diffusion FGR model originated from FRAPCON-III code is successfully transplanted in the FEMAXI-IV code and thoroughly reviewed and compared with single stage diffusion FGR model with grain boundary saturation of the FEMAXI-IV code. According to the benchmarking of the computation results against the high burn-up in-pile data it turns out that both predict quite well though the single stage diffusion FGR model somewhat underestimates the release rate. These results will be able to be applicable for the

  5. Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

    DEFF Research Database (Denmark)

    Moller, Kasper T.; Sheppard, Drew; Ravnsbaek, Dorthe B.

    2017-01-01

    Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage...... field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted...... inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy....

  6. Observations on Hydride Structures at the Tip of Arrested Cracks Grown under Conditions of Delayed Hydride Cracking

    International Nuclear Information System (INIS)

    Pettersson, Kjell; Oskarsson, Magnus; Bergqvist, Hans

    2003-04-01

    One sample of Zr2.5%Nb and one sample of cold worked and stress relieved Zircaloy-4 which have been tested for hydrogen induced crack growth have been examined in the crack tip region with the aim of determining the mechanism behind the growth of cracks. The proposed mechanisms are brittle failure of a crack tip hydride and hydrogen enhanced localized shear. The examinations were done by TEM and SEM. However attempts to produce a TEM specimen with a thinned region at the tip of the crack were unsuccessful in both samples. One feature observed in the Zr2.5%Nb material may however be an indication of intense shear deformation at the tip of the crack. On the other hand all observations on the Zircaloy-4 sample indicate precipitation of hydrides ahead of the crack tip and the presence of hydrides on the crack flanks

  7. Effectiveness of therapeutic barium enema for diverticular hemorrhage.

    Science.gov (United States)

    Matsuura, Mizue; Inamori, Masahiko; Nakajima, Atsushi; Komiya, Yasuhiko; Inoh, Yumi; Kawasima, Keigo; Naitoh, Mai; Fujita, Yuji; Eduka, Akiko; Kanazawa, Noriyoshi; Uchiyama, Shiori; Tani, Rie; Kawana, Kennichi; Ohtani, Setsuya; Nagase, Hajime

    2015-05-14

    To evaluate the effectiveness of barium impaction therapy for patients with colonic diverticular bleeding. We reviewed the clinical charts of patients in whom therapeutic barium enema was performed for the control of diverticular bleeding between August 2010 and March 2012 at Yokohama Rosai Hospital. Twenty patients were included in the review, consisting of 14 men and 6 women. The median age of the patients was 73.5 years. The duration of the follow-up period ranged from 1 to 19 mo (median: 9.8 mo). Among the 20 patients were 11 patients who required the procedure for re-bleeding during hospitalization, 6 patients who required it for re-bleeding that developed after the patient left the hospital, and 3 patients who required the procedure for the prevention of re-bleeding. Barium (concentration: 150 w%/v%) was administered per the rectum, and the leading edge of the contrast medium was followed up to the cecum by fluoroscopy. After confirmation that the ascending colon and cecum were filled with barium, the enema tube was withdrawn, and the patient's position was changed every 20 min for 3 h. Twelve patients remained free of re-bleeding during the follow-up period (range: 1-19 mo) after the therapeutic barium enema, including 9 men and 3 women with a median age of 72.0 years. Re-bleeding occurred in 8 patients including 5 men and 3 women with a median age of 68.5 years: 4 developed early re-bleeding, defined as re-bleeding that occurs within one week after the procedure, and the remaining 4 developed late re-bleeding. The DFI (disease-free interval) decreased 0.4 for 12 mo. Only one patient developed a complication from therapeutic barium enema (colonic perforation). Therapeutic barium enema is effective for the control of diverticular hemorrhage in cases where the active bleeding site cannot be identified by colonoscopy.

  8. Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Joe P.; Manship, Daniel R.; Wright, Timothy G., E-mail: Tim.Wright@nottingham.ac.uk [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Breckenridge, W. H. [Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States)

    2014-02-28

    We study both the rare gas hydride anions, RG–H{sup −} (RG = He–Rn) and Group 2 (Group IIa) metal hydride anions, M{sub IIa}H{sup −} (M{sub IIa} = Be–Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be–He complex. While the RG–H{sup −} and Be–He species are weakly bound, we show that, as with the previously studied BeH{sup −} and MgH{sup −} species, the other M{sub IIa}H{sup −} species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns{sup 2}) and H{sup −}(1s{sup 2}). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the M{sub IIa}H{sup −} species than for RG–H{sup −}. Our analyses lead us to conclude that the stronger interaction in the case of the M{sub IIa}H{sup −} species arises from sp and spd hybridization, which allows electron density on the M{sub IIa} atom to move away from the incoming H{sup −}.

  9. Uranium Hydride Nucleation and Growth Model FY'16 ESC Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Richards, Andrew Walter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Holby, Edward F. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schulze, Roland K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-12-20

    Uranium hydride corrosion is of great interest to the nuclear industry. Uranium reacts with water and/or hydrogen to form uranium hydride which adversely affects material performance. Hydride nucleation is influenced by thermal history, mechanical defects, oxide thickness, and chemical defects. Information has been gathered from past hydride experiments to formulate a uranium hydride model to be used in a Canned Subassembly (CSA) lifetime prediction model. This multi-scale computer modeling effort started in FY’13, and the fourth generation model is now complete. Additional high-resolution experiments will be run to further test the model.

  10. Air (CO2) double-contrast barium enteroclysis.

    Science.gov (United States)

    Maglinte, Dean D T; Kohli, Marc D; Romano, Stefania; Lappas, John C

    2009-09-01

    In the 1980s and 1990s in North America and Europe, air (CO(2)) double-contrast barium enteroclysis took a back seat to biphasic methylcellulose double-contrast enteroclysis in the investigation of small-bowel diseases. The widespread application of capsule endoscopy in the 21st century has identified a number of limitations of radiologic examinations in the investigation of mucosal diseases of the small intestine. Evidence-based studies comparing barium, computed tomographic (CT), and magnetic resonance (MR) enteroclysis have shown that in spite of improvements in small-bowel examination methods using CT and MR, barium examinations remain superior in the depiction of mucosal abnormalities, particularly the apthoid lesions of early Crohn disease. Barium small-bowel examinations have been recommended in the patient with a negative CT or MR enteroclysis study where the pretest probability of Crohn disease is high. A recent prospective comparison of methylcellulose double-contrast barium enteroclysis to capsule endoscopy with review of the literature has shown that air enteroclysis depicts mucosal details better than does methylcellulose double-contrast enteroclysis because of the "washout" effect of methylcellulose on superficial mucosal features. Recent articles have shown that air enteroclysis compares favorably with wireless capsule endoscopy and double-balloon endoscopy in the diagnosis of mucosal abnormalities of the small bowel. This article describes the authors' technique of performing air double-contrast enteroclysis, its clinical indications, and its pitfalls.

  11. Creating unstable velocity-space distributions with barium injections

    International Nuclear Information System (INIS)

    Pongratz, M.B.

    1983-01-01

    Large Debye lengths relative to detector dimensions and the absence of confining walls makes space an attractive laboratory for studying fundamental theories of plasma instabilities. However, natural space plasmas are rarely found displaced from equilibrium enough to permit isolation and diagnosis of the controlling parameters and driving conditions. Furthermore, any plasma or field response to the departure from equilibrium can be masked by noise in the natural system. Active experiments provide a technique for addressing the chicken or egg dilemma. Early thermite barium releases were generally conducted at low altitudes from sounding rockets to trace electric fields passively or to study configuration-space instabilities. One can also study velocity-space instabilities with barium releases. Neutral barium vapor releases wherein a typical speed greatly exceeds the thermal speed can be used to produce barium ion velocity-space distributions that should be subject to a number of microinstabilities. We examine the ion velocity-space distributions resulting from barium injections from orbiting spacecraft and shaped-charges

  12. Preparation of barium hexaferrite powders using oxidized steel scales waste

    Science.gov (United States)

    Septiani, Ardita; Idayanti, Novrita; Kristiantoro, Tony

    2016-02-01

    Research on preparation of barium hexaferrite powders has been done using Hot Strip Mill scales as raw materials. Hot Strip Mill scales are oxidized steel scales waste from steel industrial process. The method used for preparing the barium hexaferrite powders was solid state reaction method. Oxidized steel scales were milled using ball mill for 10 hours, then screened through a 250 mesh sieve to obtain powders with maximum size of 63 µm. Powders were roasted at 600°C temperature for 4 hours to obtain hematite (Fe2O3) phase. Roasted powders were then mixed with barium carbonate, and were subsequently milled for 16 hours. After mixing, powders were calcined with an increasing rate of 10°C/min and maintained at 1100°C for 3 hours. Calcination process was performed to acquire barium hexaferrite phase. X-ray Diffraction (XRD) characterization in conjunction with RIR analysis showed that 85 wt. % of barium hexaferrite is formed. The magnetic properties of powders were characterized using Permagraph. It is found the value of remanent induction is 1.09 kG, coercivity of 2.043 kOe, and the maximum energy product of 0.25 MGOe.

  13. Quantifying the stress fields due to a delta-hydride precipitate in alpha-Zr matrix

    Energy Technology Data Exchange (ETDEWEB)

    Tummala, Hareesh [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-19

    This report is a preliminary study on δ-hydride precipitate in zirconium alloy performed using 3D discrete dislocation dynamics simulations. The ability of dislocations in modifying the largely anisotropic stress fields developed by the hydride particle in a matrix phase is addressed for a specific dimension of the hydride. The influential role of probable dislocation nucleation at the hydride-matrix interface is reported. Dislocation nucleation around a hydride was found to decrease the shear stress (S13) and also increase the normal stresses inside the hydride. We derive conclusions on the formation of stacks of hydrides in zirconium alloys. The contribution of mechanical fields due to dislocations was found to have a non-negligible effect on such process.

  14. Barium Depletion in the NSTAR Discharge Cathode After 30,000 Hours of Operation

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2010-01-01

    Dispenser hollow cathodes rely on a consumable supply of barium released by impregnant materials in the pores of a tungsten matrix to maintain a low work function surface. Examinations of cathode inserts from long duration ion engine tests show deposits of tungsten at the downstream end that appear to block the flow of barium from the interior. In addition, a numerical model of barium transport in the insert plasma indicates that the barium partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant barium-producing reaction, and it was postulated previously that this would suppress barium loss in the upstream part of the insert. New measurements of the depth of barium depletion from a cathode insert operated for 30,352 hours reveal that barium loss is confined to a narrow region near the downstream end, confirming this hypothesis.

  15. Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films

    International Nuclear Information System (INIS)

    Amin-Ahmadi, Behnam; Connétable, Damien; Fivel, Marc; Tanguy, Döme; Delmelle, Renaud; Turner, Stuart; Malet, Loic; Godet, Stephane; Pardoen, Thomas; Proost, Joris; Schryvers, Dominique

    2016-01-01

    The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations.

  16. Electrochemical hydride generation atomic absorption spectrometry for determination of cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Arbab-Zavar, M.H. [Department of Chemistry, Faculty of Science, Ferdowsi University, Mashhad (Iran, Islamic Republic of)]. E-mail: arbab@um.ac.ir; Chamsaz, M. [Department of Chemistry, Faculty of Science, Ferdowsi University, Mashhad (Iran, Islamic Republic of); Youssefi, A. [Pare-Taavous Research Institute, Mashhad (Iran, Islamic Republic of); Aliakbari, M. [Department of Chemistry, Faculty of Science, Ferdowsi University, Mashhad (Iran, Islamic Republic of)

    2005-08-01

    An electrolytic hydride generation system for determination of another hydride forming element, cadmium, by catholyte variation electrochemical hydride generation (EcHG) atomic absorption spectrometry is described. A laboratory-made electrolytic cell with lead-tin alloy as cathode material is designed as electrolytic generator of molecular hydride. The influences of several parameters on the analytical signal have been evaluated using a Plackett-Burman experimental design. The significant parameters such as cathode surface area, electrolytic current, carrier gas flow rate and catholyte concentration have been optimized using univariate method. The analytical figures of merit of procedure developed were determined. The calibration curve was linear up to 20 ng ml{sup -1}of cadmium. The concentration detection limit (3{sigma}, n = 8) of 0.2 ng ml{sup -1} and repeatability (relative standard deviation, n = 7) of 3.1% were achieved at 10.0 ng ml{sup -1}. It was shown that interferences from major constituents at high concentrations were significant. The accuracy of method was verified using a real sample (spiked tap water) by standard addition calibration technique. Recovery of 104% was achieved for Cd in the spiked tap water sample.

  17. Metal Hydride assited contamination on Ru/Si surfaces

    NARCIS (Netherlands)

    Pachecka, Malgorzata; Lee, Christopher James; Sturm, Jacobus Marinus; Bijkerk, Frederik

    2013-01-01

    In extreme ultraviolet lithography (EUVL) residual tin, in the form of particles, ions, and atoms, can be deposited on nearby EUV optics. During the EUV pulse, a reactive hydrogen plasma is formed, which may be able to react with metal contaminants, creating volatile and unstable metal hydrides that

  18. Design and integration of a hydrogen storage on metallic hydrides

    International Nuclear Information System (INIS)

    Botzung, M.

    2008-01-01

    This work presents a hydrogen storage system using metal hydrides for a Combined Heat and Power (CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures (≤ 3.5 bar) and low temperatures (≤ 75 C: fuel cell temperature). During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed to obtain good compactness and to reach high absorption/desorption rates. At first, the storage system has been tested in accordance with project specifications (absorption 3.5 bar, desorption 1.5 bar). Then, the hydrogen charge/discharge times have been decreased to reach system limits. System design has been used to simulate thermal and mass comportment of the storage tank. The model is based on the software Fluent. We take in consideration heat and mass transfers in the porous media during absorption/desorption. The hydride thermal and mass behaviour has been integrated in the software. The heat and mass transfers experimentally obtained have been compared to results calculated by the model. The influence of experimental and numerical parameters on the model behaviour has also been explored. (author) [fr

  19. Process of forming a sol-gel/metal hydride composite

    Science.gov (United States)

    Congdon, James W [Aiken, SC

    2009-03-17

    An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.

  20. Fractal analysis of electrolytically-deposited palladium hydride dendrites

    International Nuclear Information System (INIS)

    Bursill, L.A.; Julin, Peng; Xudong, Fan.

    1990-01-01

    The fractal scaling characteristics of the surface profile of electrolytically-deposited palladium hydride dendritic structures have been obtained using conventional and high resolution transmission electron microscopy. The results are in remarkable agreement with the modified diffusion-limited aggregation model. 19 refs., 3 tabs., 13 figs

  1. A system of hydrogen powered vehicles with liquid organic hydrides

    International Nuclear Information System (INIS)

    Taube, M.

    1981-07-01

    A motor car system based on the hydrogen produced by nuclear power stations during the night in the summer, and coupled with organic liquid hydride seems to be a feasible system in the near future. Such a system is discussed and the cost is compared with gasoline. (Auth.)

  2. The Properties of Some Simple Covalent Hydrides: An Ab Initio ...

    African Journals Online (AJOL)

    Some properties of the monomeric binary hydrides of the elements of the first two rows of the periodic table have been determined using ab initio molecular orbital theory. The properties in question are the energetic, structural, electronic, topological and vibrational characteristics. In general, a gradual convergence towards ...

  3. Aluminium hydride: a reversible material for hydrogen storage.

    Science.gov (United States)

    Zidan, Ragaiy; Garcia-Diaz, Brenda L; Fewox, Christopher S; Stowe, Ashley C; Gray, Joshua R; Harter, Andrew G

    2009-07-07

    Aluminium hydride has been synthesized electrochemically, providing a synthetic route which closes a reversible cycle for regeneration of the material and bypasses expensive thermodynamic costs which have precluded AlH(3) from being considered as a H(2) storage material.

  4. New Orbital Hybridization Schemes for Metal Hydrides-Keeping p ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 8. New Orbital Hybridization Schemes for Metal Hydrides - Keeping p Orbitals out of the Picture. J Chandrasekhar. Research News ... J Chandrasekhar1. Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India ...

  5. Optimization of Internal Cooling Fins for Metal Hydride Reactors

    Directory of Open Access Journals (Sweden)

    Vamsi Krishna Kukkapalli

    2016-06-01

    Full Text Available Metal hydride alloys are considered as a promising alternative to conventional hydrogen storage cylinders and mechanical hydrogen compressors. Compared to storing in a classic gas tank, metal hydride alloys can store hydrogen at nearly room pressure and use less volume to store the same amount of hydrogen. However, this hydrogen storage method necessitates an effective way to reject the heat released from the exothermic hydriding reaction. In this paper, a finned conductive insert is adopted to improve the heat transfer in the cylindrical reactor. The fins collect the heat that is volumetrically generated in LaNi5 metal hydride alloys and deliver it to the channel located in the center, through which a refrigerant flows. A multiple-physics modeling is performed to analyze the transient heat and mass transfer during the hydrogen absorption process. Fin design is made to identify the optimum shape of the finned insert for the best heat rejection. For the shape optimization, use of a predefined transient heat generation function is proposed. Simulations show that there exists an optimal length for the fin geometry.

  6. Diastereoselectivity in the reduction of bicyclic enones with hindered hydrides

    OpenAIRE

    Camozzato, Andreza C.; Tenius, Beatriz S. M.; Oliveira, Eduardo R. de; Viegas Jr., Cláudio; Victor, Maurício M.; Silveira, Leandro G. da

    2008-01-01

    Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride®) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring.

  7. Diastereoselectivity in the reduction of bicyclic enones with hindered hydrides

    International Nuclear Information System (INIS)

    Camozzato, Andreza C.; Tenius, Beatriz S. M.; Oliveira, Eduardo R. de; Viegas Junior, Claudio; Victor, Mauricio M.; Silveira, Leandro G. da

    2008-01-01

    Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride R ) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring. (author)

  8. Centrifugal Jet Spinning for Highly Efficient and Large-scale Fabrication of Barium Titanate Nanofibers

    OpenAIRE

    Ren, Liyun; Kotha, Shiva P.

    2013-01-01

    The centrifugal jet spinning (CJS) method has been developed to enable large-scale synthesis of barium titanate nanofibers. Barium titanate nanofibers with fiber diameters down to 50 nm and grain sizes around 25 nm were prepared with CJS by spinning a sol-gel solution of barium titanate and poly(vinylpyrrolidone) with subsequent heat treatment at 850 °C. XRD and FTIR analysis demonstrated high purity and tetragonal perovskite structured barium titanate nanofibers. SEM and TEM images confirm t...

  9. Activation and discharge kinetics of metal hydride electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Stein Egil

    2003-07-01

    Potential step chronoamperometry and Electrochemical Impedance Spectroscopy (eis) measurements were performed on single metal hydride particles. For the {alpha}-phase, the bulk diffusion coefficient and the absorption/adsorption rate parameters were determined. Materials produced by atomisation, melt spinning and conventional casting were investigated. The melt spun and conventional cast materials were identical and the atomised material similar in composition. The particles from the cast and the melt spun material were shaped like parallelepipeds. A corresponding equation, for this geometry, for diffusion coupled to an absorption/adsorption reaction was developed. It was found that materials produced by melt spinning exhibited lower bulk diffusion (1.7E-14 m2/s) and absorption/adsorption reaction rate (1.0E-8 m/s), compared to materials produced by conventionally casting (1.1E-13 m2/s and 5.5E-8 m/s respectively). In addition, the influence of particle active surface and relative diffusion length were discussed. It was concluded that there are uncertainties connected to these properties, which may explain the large distribution in the kinetic parameters measured on metal hydride particles. Activation of metal hydride forming materials has been studied and an activation procedure, for porous electrodes, was investigated. Cathodic polarisation of the electrode during a hot alkaline surface treatment gave the maximum discharge capacity on the first discharge of the electrode. The studied materials were produced by gas atomisation and the spherical shape was retained during the activation. Both an AB{sub 5} and an AB{sub 2} alloy was successfully activated and discharge rate properties determined. The AB{sub 2} material showed a higher maximum discharge capacity, but poor rate properties, compared to the AB{sub 5} material. Reduction of surface oxides, and at the same time protection against corrosion of active metallic nickel, can explain the satisfying results of

  10. Occupational doses in pediatric barium meal procedures

    International Nuclear Information System (INIS)

    Filipov, D.; Schelin, H.R.; Denyak, V.; Legnani, A.; Ledesma, J.A.; Paschuk, S.A.; Sauzen, J.; Yagui, A.; Hoff, G.; Khoury, H.J.

    2015-01-01

    Ionizing radiation has become an indispensable tool when it comes to diagnosis and therapy. However, its use should happen in a rational manner, taking into account the risks to which the staff is being exposed. Barium meal (BM), or upper gastrointestinal (GI) studies, using fluoroscopy, are widely used for gastroesophageal reflux disease diagnostic in children and professionals are required to stay inside the examination room to position and immobilize pediatric patients during the procedure. Therefore, it is very important that proffessionals strictly follow the technical standards of radiation protection. According to the ICRP and the NCRP recommendations, the annual limit equivalent doses for eyes, thyroid and hands are, espectively, 20 mSv, 150 mSv and 500 mSv. Based on those data, the aim of the current study is to estimate the annual equivalent dose for eyes, thyroid and hands of professionals who perform BM procedures in children. This was done using properly package LiF:Mg,Cu,P thermoluminescent dosimeters in 37 procedures; 2 pairs were positioned near each staff´s eye, 2 pairs on each professional´s neck (on and under the lead protector) and 2 pairs on both staff´s hands. The range of the estimative annual equivalent doses, for eyes, thyroid and hands, are, respectively: 14 – 36 mSv, 7 – 22 mSv and 14 – 58 mSv. Only the closest staff to the patient exceeded the annual equivalent doses in the eyes (around 80% higher than the limit set by ICRP). However, the results from this study, for hands and thyroid, compared to similar studies, show higher values. Therefore, the optimization implementation is necessary, so that the radiation levels can be reduced. (authors)

  11. Selectivity in biomineralization of barium and strontium.

    Science.gov (United States)

    Krejci, Minna R; Wasserman, Brian; Finney, Lydia; McNulty, Ian; Legnini, Daniel; Vogt, Stefan; Joester, Derk

    2011-11-01

    The desmid green alga Closterium moniliferum belongs to a small number of organisms that form barite (BaSO(4)) or celestite (SrSO(4)) biominerals. The ability to sequester Sr in the presence of an excess of Ca is of considerable interest for the remediation of (90)Sr from the environment and nuclear waste. While most cells dynamically regulate the concentration of the second messenger Ca(2+) in the cytosol and various organelles, transport proteins rarely discriminate strongly between Ca, Sr, and Ba. Herein, we investigate how these ions are trafficked in C. moniliferum and how precipitation of (Ba,Sr)SO(4) crystals occurs in the terminal vacuoles. Towards this goal, we simultaneously visualize intracellular dynamics of multiple elements using X-ray fluorescence microscopy (XFM) of cryo-fixed/freeze-dried samples. We correlate the resulting elemental maps with ultrastructural information gleaned from freeze-fracture cryo-SEM of frozen-hydrated cells and use micro X-ray absorption near edge structure (micro-XANES) to determine sulfur speciation. We find that the kinetics of Sr uptake and efflux depend on external Ca concentrations, and Sr, Ba, and Ca show similar intracellular localization. A highly ion-selective cross-membrane transport step is not evident. Based on elevated levels of sulfate detected in the terminal vacuoles, we propose a "sulfate trap" model, where the presence of dissolved barium leads to preferential precipitation of (Ba,Sr)SO(4) due to its low solubility relative to SrSO(4) and CaSO(4). Engineering the sulfate concentration in the vacuole may thus be the most direct way to increase the Sr sequestered per cell, an important consideration in using desmids for phytoremediation of (90)Sr. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Gastrointestinal tract wall visualization and distention during abdominal and pelvic multidetector CT with a neutral barium sulphate suspension: comparison with positive barium sulphate suspension and with water.

    Science.gov (United States)

    Oliva, M R; Erturk, S M; Ichikawa, T; Rocha, T; Ros, P R; Silverman, S G; Mortele, K J

    2012-01-01

    When examining patients with contrast-enhanced multidetector-row CT, we determined if the stomach and small bowel were visualized and distended better with a neutral barium sulphate suspension than with positive barium sulphate suspension or water. After obtaining approval from our institutional review board, 156 patients (women: 84; mean age: 54 yrs) with no history of gastrointestinal tract disease were randomized prospectively to receive orally either 900 ml of neutral (0.1% w/v) barium sulphate suspension (n = 53), 900 ml of positive (2.1% w/v) barium sulphate suspension (n = 53), or 900 ml of water (n = 50), prior to undergoing contrast-enhanced abdominal and pelvic multidetector-row CT. Two independent radiologists evaluated the stomach, and small bowel, for luminal distension and wall visualization, using a five point scale. Results were compared using Kruskal-Wallis and Mann-Whitney U tests. The walls of the stomach, and small bowel were visualized better in patients who were administered neutral barium sulphate suspension than those who were administered either positive barium sulphate suspension (p barium sulphate suspension, the stomach and small bowel were distended better compared to patients administered water (p barium sulphate suspension (p contrast-enhanced abdominal and pelvic multidetector-row CT, orally administered neutral barium sulphate suspension allows the gastrointestinal tract to be visualized and distended better than either positive barium sulphate suspension, or water.

  13. Inert blanketing of a hydride bed using typical grade protium

    Energy Technology Data Exchange (ETDEWEB)

    Klein, J.E. [Savannah River National Laboratory, Aiken (United States)

    2015-03-15

    This paper describes the impact of 500 ppm (0.05%) impurities in protium on the absorption rate of a 9.66 kg LaNi{sub 4.25}Al{sub 0.75} (LANA0.75) metal hydride bed. The presence of 500 ppm or less inerts (i.e. non-hydrogen isotopes) can significantly impact hydrogen bed absorption rates. The impact on reducing absorption rates is significantly greater than predicted assuming uniform temperature, pressure, and compositions throughout the bed. Possible explanations are discussed. One possibility considered was the feed gas contained impurity levels higher than 500 ppm. It was shown that a level of 5000 ppm of inerts would have been necessary to fit the experimental result so this possibility wa dismissed. Another possibility is that the impurities in the protium supply reacted with the hydride material and partially poisoned the hydride. If the hydride were poisoned with CO or another impurity, the removal of the over-pressure gas in the bed would not be expected to allow the hydride loading of the bed to continue as the experimental results showed, so this possibility was also dismissed. The last possibility questions the validity of the calculations. It is assumed in all the calculations that the gas phase composition, temperature, and pressure are uniform throughout the bed. These assumptions are less valid for large beds where there can be large temperature, pressure, and composition gradients throughout the bed. Eventually the impact of 0.05% inerts in protium on bed absorption rate is shown and explained in terms of an increase in inert partial pressure as the bed was loaded.

  14. Synthesis of hydrides by interaction of intermetallic compounds with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, Boris P., E-mail: tarasov@icp.ac.ru [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Fokin, Valentin N.; Fokina, Evelina E. [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Yartys, Volodymyr A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, Kjeller NO 2027 (Norway); Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim NO 7491 (Norway)

    2015-10-05

    Highlights: • Interaction of the intermetallics A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} with NH{sub 3} was studied. • The mechanism of interaction of the alloys with ammonia is temperature-dependent. • Hydrides, hydridonitrides, disproportionation products or metal–N–H compounds are formed. • NH{sub 4}Cl was used as an activator of the reaction between ammonia and intermetallics. • Interaction with ammonia results in the synthesis of the nanopowders. - Abstract: Interaction of intermetallic compounds with ammonia was studied as a processing route to synthesize hydrides and hydridonitrides of intermetallic compounds having various stoichiometries and types of crystal structures, including A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} (A = Mg, Ti, Zr, Sc, Nd, Sm; B = transition metals, including Fe, Co, Ni, Ti and nontransition elements, Al and B). In presence of NH{sub 4}Cl used as an activator of the reaction between ammonia and intermetallic alloys, their interaction proceeds at rather mild P–T conditions, at temperatures 100–200 °C and at pressures of 0.6–0.8 MPa. The mechanism of interaction of the alloys with ammonia appears to be temperature-dependent and, following a rise of the interaction temperature, it leads to the formation of interstitial hydrides; interstitial hydridonitrides; disproportionation products (binary hydride; new intermetallic hydrides and binary nitrides) or new metal–nitrogen–hydrogen compounds like magnesium amide Mg(NH{sub 2}){sub 2}. The interaction results in the synthesis of the nanopowders where hydrogen and nitrogen atoms become incorporated into the crystal lattices of the intermetallic alloys. The nitrogenated materials have the smallest particle size, down to 40 nm, and a specific surface area close to 20 m{sup 2}/g.

  15. Barium titanate thick films prepared by screen printing technique

    Directory of Open Access Journals (Sweden)

    Mirjana M. Vijatović

    2010-06-01

    Full Text Available The barium titanate (BaTiO3 thick films were prepared by screen printing technique using powders obtained by soft chemical route, modified Pechini process. Three different barium titanate powders were prepared: i pure, ii doped with lanthanum and iii doped with antimony. Pastes for screen printing were prepared using previously obtained powders. The thick films were deposited onto Al2O3 substrates and fired at 850°C together with electrode material (silver/palladium in the moving belt furnace in the air atmosphere. Measurements of thickness and roughness of barium titanate thick films were performed. The electrical properties of thick films such as dielectric constant, dielectric losses, Curie temperature, hysteresis loop were reported. The influence of different factors on electrical properties values was analyzed.

  16. Diagnostic role of barium enema in carcinoma rectum

    International Nuclear Information System (INIS)

    Asghar, M.

    2003-01-01

    Objective: The main aim of this barium enema study was to evaluate its role in patients suspected to have rectal pathologies with complaints of change in bowel habit, anorexia/weight loss, bleeding per rectum and acute/sub-acute colonic obstruction. Results: barium enema study as screening test for colo-rectal carcinoma was undertaken. Contrast outlined the colonic growth in 35 cases, out of which the cases of carcinoma colon were 24 including 13 patients suffering from carcinoma rectum. The percentage of carcinoma colon to total colonic growth was 68% while, carcinoma rectum to total carcinoma colon was 54%. Conclusion: On the basis of these investigations, it is concluded that patient's compliance is important factor in the early detection of colonic neoplasia. Though results of colonoscopy are more reliable but in practice, barium enema (double contrast) is performed initially to outline the lesion and then colonoscopy for biopsy purpose. (author)

  17. 49 CFR 173.182 - Barium azide-50 percent or more water wet.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Barium azide-50 percent or more water wet. 173.182 Section 173.182 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Class 1 and Class 7 § 173.182 Barium azide—50 percent or more water wet. Barium azide—50 percent or more...

  18. 75 FR 36629 - Barium Chloride From the People's Republic of China: Continuation of Antidumping Duty Order

    Science.gov (United States)

    2010-06-28

    ... International Trade Administration Barium Chloride From the People's Republic of China: Continuation of... the antidumping duty order on barium chloride from the People's Republic of China (``PRC'') would... of initiation of the third sunset review of the antidumping duty order on barium chloride from the...

  19. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN P-00...

  20. The diagnosis of gastro-esophageal reflux disease cannot be made with barium esophagograms

    NARCIS (Netherlands)

    Saleh, C. M. G.; Smout, A. J. P. M.; Bredenoord, A. J.

    2015-01-01

    For over 50 years, barium studies have been used to diagnose gastro-esophageal reflux disease (GERD), but the value of this test is controversial. Our study aimed to determine if barium esophagograms can be used to diagnose GERD. Barium esophagograms and pH-impedance measurement were performed in 20

  1. Measurement of Elastic Modulus of Alumina and Barium Strontium Titanate Wafers Produced by Tape Casting Method

    Science.gov (United States)

    2014-02-01

    DATES COVERED (From – To) 4. TITLE AND SUBTITLE MEASUREMENT OF ELASTIC MODULUS OF ALUMINA AND BARIUM STRONTIUM TITANATE WAFERS PRODUCED BY...configuration testing method. Samples of barium strontium titanate (BST) were made using a regular powder pressing, sintering, pelletizing, and...fabricated using thin wafers of barium strontium titanate (BST) and aluminum oxide (alumina) ceramic during launch of a system. Sandia National

  2. Diagnosis of anastomotic leak: electrolyte detection versus barium fluoroscopy.

    Science.gov (United States)

    DeArmond, Daniel T; Carswell, Aimee; Louden, Christopher L; Simmons, Jeremy D; Bayer, Johanna; Das, Nitin A; Johnson, Scott B

    2013-06-15

    We recently described a new method of diagnosing anastomotic leak using the detection of electrical changes induced by electrolyte extravasation from a surgically created gastric leak site in experimental rats. We sought to compare the sensitivity and specificity of anastomotic leak detection for this method to that of upper gastrointestinal (GI) barium fluoroscopy. Experimental rats with a surgically created gastric leak site and controls were interrogated as to the presence of leak using either the electrolyte-gated leak detection method or upper GI barium fluoroscopy. The sensitivity and specificity of leak detection for the two methods were compared. The sensitivity and specificity of electrolyte-gated leak detection were both 100% (95% confidence interval 69-100%). Barium upper GI fluoroscopy misidentified one leak as a control and one control as a leak, for a sensitivity and specificity of 80% each (95% confidence interval 37-97%). No statistically significant difference was seen between electrolyte-gated leak detection and barium upper GI fluoroscopy in terms of the sensitivity and specificity of anastomotic leak detection. Electrolyte-gated leak detection was similarly sensitive and specific for anastomotic leak detection as upper GI barium fluoroscopy, the current standard. The electrolyte-gated method has the advantages of an inert contrast agent (normal saline) and the possibility of performing leak interrogation at the bedside. Electrolyte-gated leak detection might represent a plausible alternative to upper GI barium fluoroscopy for routine postoperative anastomotic leak surveillance after esophagectomy or other foregut surgery. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Compact pulse forming line using barium titanate ceramic material.

    Science.gov (United States)

    Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 Ω load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. © 2011 American Institute of Physics

  4. Reaction sintering of a zirconia-containing barium feldspar ceramic

    International Nuclear Information System (INIS)

    Nordmann, A.; Cheng, Y-B.; Muddle, B. C.

    1996-01-01

    Zircon (ZrSiO 4 ) is a natural mineral resource known to react with certain oxides to produce a dispersion of zirconia particles within ceramic or glass-ceramic matrices. Barium aluminosilicates, particularly the celsian polymorphs of BaO- Al 2 O 3 2SiO 2 display oxidation resistance and refractory characteristics commensurate with the properties required of high temperature materials. Such properties, coupled with the high melting point of ZrO 2 (2680 deg C), suggest that barium aluminosilicates and zirconia are an ideal combination from which to fabricate high temperature materials. A recent study has indicated that a barium aluminosilicate containing up to 40mol% ZrO 2 can be prepared via a sol-gel process. However, the desire to utilise a natural resource in the form of zircon in the present work has led to the choice of reaction sintering as an alternative processing route. The current work was undertaken to investigate the possibility of forming a zirconia-containing barium feldspar composite material using the reaction sintering of zircon and assuming the following stoichiometric reaction: 2ZrSiO 4 + BaCO 3 + Al 2 O 3 → 2ZrO 2 + BaO-Al 2 O 3 -2SiO 2 + CO 2 ↑. The reaction sintering of zircon with alumina and barium carbonate produces a composite material comprising distributed ZrO 2 in a continous barium feldspar matrix. Yttria added during processing allows a significant fraction of the ZrO 2 to be retained as tetragonal phase to room temperature and thus the potential for a measure of transformation toughening

  5. Esophageal intramural pseudodiverticulosis characterized by barium esophagography: a case report

    LENUS (Irish Health Repository)

    O'Connor, Owen J

    2010-05-21

    Abstract Introduction Esophageal intramural pseudodiverticulosis is a rare condition characterized by the dilatation of the submucosal glands. Case presentation We present a case of esophageal intramural pseudodiverticulosis in a 72-year-old Caucasian man who presented with dysphagia and with a background history of alcohol abuse. An upper gastrointestinal endoscopy of our patient showed an esophageal stricture with abnormal mucosal appearances, but no malignant cells were seen at biopsy. Appearances on a barium esophagram were pathognomonic for esophageal intramural pseudodiverticulosis. Conclusion We demonstrate the enduring usefulness of barium esophagography in the characterization of abnormal mucosal appearances at endoscopy.

  6. Comparison of endoscopy and barium swallow with marshmallow in dysphagia.

    Science.gov (United States)

    Somers, S; Stevenson, G W; Thompson, G

    1986-06-01

    Forty-four patients with dysphagia were examined both by endoscopy and by barium swallow with a marshmallow bolus. In these patients 36 stenoses were found: 34 by radiology and 30 by endoscopy. The radiologic criteria for stenosis included arrest of the marshmallow in a manner to support a column of barium and reproduction of the patient's symptoms at the time this occurred. Radiologic false negative findings were partly due to an inability by patients to swallow an adequate marshmallow bolus; endoscopic failures were associated with small endoscopes and mild stenoses.

  7. The Kerr nonlinearity of the beta-barium borate crystal

    DEFF Research Database (Denmark)

    Bache, Morten; Guo, Hairun; Zhou, Binbin

    2013-01-01

    A popular crystal for ultrafast cascading experiments is beta-barium-borate (β-BaB2O4, BBO). It has a decent quadratic nonlinear coefficient, and because the crystal is anisotropie it can be birefringence phase-matched for type I (oo → e) second-harmonic generation (SHG). For femtosecond experime......A popular crystal for ultrafast cascading experiments is beta-barium-borate (β-BaB2O4, BBO). It has a decent quadratic nonlinear coefficient, and because the crystal is anisotropie it can be birefringence phase-matched for type I (oo → e) second-harmonic generation (SHG). For femtosecond...

  8. Methods for producing monodispersed particles of barium titanate

    Science.gov (United States)

    Hu, Zhong-Cheng

    2001-01-01

    The present invention is a low-temperature controlled method for producing high-quality, ultrafine monodispersed nanocrystalline microsphere powders of barium titanate and other pure or composite oxide materials having particles ranging from nanosized to micronsized particles. The method of the subject invention comprises a two-stage process. The first stage produces high quality monodispersed hydrous titania microsphere particles prepared by homogeneous precipitation via dielectric tuning in alcohol-water mixed solutions of inorganic salts. Titanium tetrachloride is used as an inorganic salt precursor material. The second stage converts the pure hydrous titania microsphere particles into crystalline barium titanate microsphere powders via low-temperature, hydrothermal reactions.

  9. Preparation, structure and dielectric property of barium stannate titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wei Xiaoyong [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi' an Jiaotong Univesity, Xi' an 710049 (China)]. E-mail: wdy@mail.xjtu.edu.cn; Yao Xi [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi' an Jiaotong Univesity, Xi' an 710049 (China)

    2007-02-25

    The processing route of barium stannate titanate ceramics were optimized to prepare full composition range solid solution sample. The phase structure, microscopic morphology and dielectric properties of barium stannate titanate ceramics were studied. X-ray diffraction patterns indicated that the samples are of single perovskite structure. Linear empirical relationship between crystal lattice and tin content was proposed. This relationship is valid covering the full composition range, which suggests that this solid solution system is ultimate mutual soluble. The phase transition behavior was studied and a phase diagram was obtained based on the dielectric measurements.

  10. Effect of hydrogenation conditions on the microstructure and mechanical properties of zirconium hydride

    Science.gov (United States)

    Muta, Hiroaki; Nishikane, Ryoji; Ando, Yusuke; Matsunaga, Junji; Sakamoto, Kan; Harjo, Stefanus; Kawasaki, Takuro; Ohishi, Yuji; Kurosaki, Ken; Yamanaka, Shinsuke

    2018-03-01

    Precipitation of brittle zirconium hydrides deteriorate the fracture toughness of the fuel cladding tubes of light water reactor. Although the hydride embrittlement has been studied extensively, little is known about physical properties of the hydride due to the experimental difficulties. In the present study, to elucidate relationship between mechanical properties and microstructure, two δ-phase zirconium hydrides and one ε-phase zirconium hydride were carefully fabricated considering volume changes at the metal-to-hydride transformation. The δ-hydride that was fabricated from α-zirconium exhibits numerous inner cracks due to the large volume change. Analyses of the neutron diffraction pattern and electron backscatter diffraction (EBSD) data show that the sample displays significant stacking faults in the {111} plane and in the pseudo-layered microstructure. On the other hand, the δ-hydride sample fabricated from β-zirconium at a higher temperature displays equiaxed grains and no cracks. The strong crystal orientation dependence of mechanical properties were confirmed by indentation test and EBSD observation. The δ-hydride hydrogenated from α-zirconium displays a lower Young's modulus than that prepared from β-zirconium. The difference is attributed to stacking faults within the {111} plane, for which the Young's modulus exhibits the highest value in the perpendicular direction. The strong influence of the crystal orientation and dislocation density on the mechanical properties should be considered when evaluating hydride precipitates in nuclear fuel cladding.

  11. Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Joseph William [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cordaro, Joseph Gabriel [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sartor, George B. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dedrick, Daniel E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Reeder, Craig L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2012-02-01

    In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. Acknowledgements The authors would like to thank the following people who participated in this project: Ned Stetson (U.S. Department of Energy) for sponsorship and support of the project. Ken Stewart (Sandia) for building the flow-through calorimeter and cycling test stations. Isidro Ruvalcaba, Jr. (Sandia) for qualitative experiments on the interaction of sodium alanate with water. Terry Johnson (Sandia) for sharing his expertise and knowledge of metal hydrides, and sodium alanate in particular. Marcina Moreno (Sandia) for programmatic assistance. John Khalil (United Technologies Research Corp) for insight into the hazards of reactive metal hydrides and real-world accident scenario experiments. Summary In an attempt to mitigate and/or manage hazards associated with storing bulk quantities of reactive metal hydrides, polymer composite materials (a mixture of a mitigating polymer and a metal hydride) were synthesized and tested

  12. Efficient catalysis by MgCl2 in hydrogen generation via hydrolysis of Mg-based hydride prepared by hydriding combustion synthesis.

    Science.gov (United States)

    Zhao, Zelun; Zhu, Yunfeng; Li, Liquan

    2012-06-04

    Magnesium chloride efficiently catalyzed the hydrolysis of Mg-based hydride prepared by hydriding combustion synthesis. Hydrogen yield of 1635 mL g(-1) was obtained (MgH(2)), i.e. with 96% conversion in 30 min at 303 K.

  13. AUTOIONIZATION OF LOW-LYING 5DNG STATES IN BARIUM

    NARCIS (Netherlands)

    van Leeuwen, R.; Ubachs, W.M.G.; Hogervorst, W.

    1994-01-01

    The autoionizing 5dng J = 1-5 states in barium for n=5-8 were investigated in a two-step pulsed laser atomic beam experiment. The wavefunctions of the 5dng configuration can be well described in a (jl)K-coupled basis. Each 5d(j)ng[K] fine structure state autoionizes into a single 6sepsilonl

  14. Ionic conductivity and diffusion coefficient of barium-chloride-based ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 4. Ionic conductivity and diffusion coefficient of barium-chloride-based polymer electrolyte with poly(vinyl alcohol)–poly(4-styrenesulphonic acid) polymer complex. MAYANK PANDEY GIRISH M JOSHI NARENDRA NATH GHOSH. Volume 40 Issue 4 August ...

  15. ORIGINAL ARTICLE ORIG ORIG Comparison of barium and ...

    African Journals Online (AJOL)

    Background. Simulation of patients with carcinoma of the oesophagus using radio-opaque contrast is a standard step in treatment planning prior to delivering radiation therapy. Various contrast mediums such as barium, gastrograffin and hexabrix have been used for simulation at different centres. Objective. The purpose of ...

  16. Barium Ferrite Films Grown By Pulsed Laser Ablation

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.; de Haan, P.; Roesthuis, F.J.G.

    1998-01-01

    Abstract available only. It is known that barium ferrite (BaFe12019) can grow with perpendicular anisotropy on A1203 a single crystal substrate,' but also on an amorphous substrate by using a ZnO buffer.2 Because of its large magnetic anisotropy which can easily overcome the shape anisotropy of the

  17. Synthesis of nanosized barium titanate/epoxy resin composites and ...

    Indian Academy of Sciences (India)

    Anechoic chamber; barium titanate; electromagnetic interference and compatibility; epoxy resin composites; microwave absorbers; radio frequency absorbers. ... The reflection loss (RL) and transmission loss (TL) of the composite materials were measured by the reflection/transmission method using a vector network ...

  18. Thermal expansion behaviour of barium and strontium zirconium ...

    Indian Academy of Sciences (India)

    Unknown

    Thermal expansion behaviour of barium and strontium zirconium phosphates. P SRIKARI TANTRI, K GEETHA†, A M UMARJI† and SHEELA K RAMASESHA*. Materials Science Division, National Aerospace Laboratories, Bangalore 560 017, India. †Materials Research Centre, Indian Institute of Science, Bangalore 560 ...

  19. Phase developments and dielectric responses of barium substituted ...

    Indian Academy of Sciences (India)

    Phase developments and dielectric responses of barium substituted four-layer CaBi4Ti4O15 Aurivillius. HUILING DU. ∗. , XIANG SHI and HUILU LI. College of Materials Science and Engineering, Xi'an University of Science and Technology, Xi'an 710054, China. MS received 26 December 2010; revised 8 February 2011.

  20. Experimental study of yttrium barium copper oxide superconducting ...

    Indian Academy of Sciences (India)

    667–676. Experimental study of yttrium barium copper oxide ... In the present study, torsional strain dependence of the critical current of the coated conductor is investigated experimentally for different current ramp rates. Again, the .... An empirical formula was proposed and established using a curve fit expressed in eq. (1).

  1. Dose-area product measurements during Barium enema radiograph ...

    African Journals Online (AJOL)

    The aim of this study was to obtain a direct measurement of the typical dose delivered to an average adult patient during a barium enema examination. Measurement was done on a sample of 50 patients at three departments, using a dose-area product (DAP) meter. The comparison of the results with UK median levels ...

  2. peroxo-oxalate preparation of doped barium titanate

    NARCIS (Netherlands)

    van der Gijp, S.; Winnubst, Aloysius J.A.; Verweij, H.

    1999-01-01

    The peroxo-oxalate complexation method is a method that can be used for the preparation of doped barium titanate. In this paper we focus on BaTi0.91Zr0.09O3, which can be used for discharge capacitors in lamp starters. The preparation method described here is based on the complexation and subsequent

  3. Thermal expansion behaviour of barium and strontium zirconium ...

    Indian Academy of Sciences (India)

    Unknown

    small substitution of barium changes its sign. X = 1⋅0 and 1⋅25 samples have almost constant CTE over the entire temperature range. The low thermal expansion of these samples can be attributed to the ordering of the ions in the crystal structure of these materials. Keywords. Coefficient of thermal expansion; low thermal ...

  4. SEPARATION OF BARIUM VALUES FROM URANYL NITRATE SOLUTIONS

    Science.gov (United States)

    Tompkins, E.R.

    1959-02-24

    The separation of radioactive barium values from a uranyl nitrate solution of neutron-irradiated uranium is described. The 10 to 20% uranyl nitrate solution is passed through a flrst column of a cation exchange resin under conditions favoring the adsorption of barium and certain other cations. The loaded resin is first washed with dilute sulfuric acid to remove a portion of the other cations, and then wash with a citric acid solution at pH of 5 to 7 to recover the barium along with a lesser amount of the other cations. The PH of the resulting eluate is adjusted to about 2.3 to 3.5 and diluted prior to passing through a smaller second column of exchange resin. The loaded resin is first washed with a citric acid solution at a pH of 3 to elute undesired cations and then with citric acid solution at a pH of 6 to eluts the barium, which is substantially free of undesired cations.

  5. FEASIBILITY OF RECYCLING PLUTONIUM AND MINOR ACTINIDES IN LIGHT WATER REACTORS USING HYDRIDE FUEL

    Energy Technology Data Exchange (ETDEWEB)

    Greenspan, Ehud; Todreas, Neil; Taiwo, Temitope

    2009-03-10

    The objective of this DOE NERI program sponsored project was to assess the feasibility of improving the plutonium (Pu) and minor actinide (MA) recycling capabilities of pressurized water reactors (PWRs) by using hydride instead of oxide fuels. There are four general parts to this assessment: 1) Identifying promising hydride fuel assembly designs for recycling Pu and MAs in PWRs 2) Performing a comprehensive systems analysis that compares the fuel cycle characteristics of Pu and MA recycling in PWRs using the promising hydride fuel assembly designs identified in Part 1 versus using oxide fuel assembly designs 3) Conducting a safety analysis to assess the likelihood of licensing hydride fuel assembly designs 4) Assessing the compatibility of hydride fuel with cladding materials and water under typical PWR operating conditions Hydride fuel was found to offer promising transmutation characteristics and is recommended for further examination as a possible preferred option for recycling plutonium in PWRs.

  6. Irradiation effects on thermal properties of LWR hydride fuel

    Science.gov (United States)

    Terrani, Kurt; Balooch, Mehdi; Carpenter, David; Kohse, Gordon; Keiser, Dennis; Meyer, Mitchell; Olander, Donald

    2017-04-01

    Three hydride mini-fuel rods were fabricated and irradiated at the MIT nuclear reactor with a maximum burnup of 0.31% FIMA or ∼5 MWd/kgU equivalent oxide fuel burnup. Fuel rods consisted of uranium-zirconium hydride (U (30 wt%)ZrH1.6) pellets clad inside a LWR Zircaloy-2 tubing. The gap between the fuel and the cladding was filled with lead-bismuth eutectic alloy to eliminate the gas gap and the large temperature drop across it. Each mini-fuel rod was instrumented with two thermocouples with tips that are axially located halfway through the fuel centerline and cladding surface. In-pile temperature measurements enabled calculation of thermal conductivity in this fuel as a function of temperature and burnup. In-pile thermal conductivity at the beginning of test agreed well with out-of-pile measurements on unirradiated fuel and decreased rapidly with burnup.

  7. Hydride precipitation in zirconium studied by pendulum techniques

    International Nuclear Information System (INIS)

    Ritchie, I.G.; Sprungmann, K.W.

    1983-12-01

    Measurements of the precipitation peak, the autotwisting strain and the properties of hydride dislocations have been used to map the hydrogen terminal solid solubility boundary in polycrystalline samples and a single-crystal sample of α-zirconium. A low-frequency torsion pendulum was employed for some of the measurements and a low-frequency flexure pendulum for others. These pendulum techniques were successful in extending measurements of the hydrogen terminal solid solubility boundary in α-zirconium to the relatively low hydrogen concentration range 2 to 50 μg/g of technological interest in the nuclear industry. In addition, the results were used to obtain qualitative and quantitative information about the stress dependence of the hydrogen terminal solid solubility boundary and the kinetics of hydride precipitation or dissolution in response to a step change in the applied stress

  8. ALUMINUM HYDRIDE: A REVERSIBLE STORAGE MATERIAL FOR HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Zidan, R; Christopher Fewox, C; Brenda Garcia-Diaz, B; Joshua Gray, J

    2009-01-09

    One of the challenges of implementing the hydrogen economy is finding a suitable solid H{sub 2} storage material. Aluminium (alane, AlH{sub 3}) hydride has been examined as a potential hydrogen storage material because of its high weight capacity, low discharge temperature, and volumetric density. Recycling the dehydride material has however precluded AlH{sub 3} from being implemented due to the large pressures required (>10{sup 5} bar H{sub 2} at 25 C) and the thermodynamic expense of chemical synthesis. A reversible cycle to form alane electrochemically using NaAlH{sub 4} in THF been successfully demonstrated. Alane is isolated as the triethylamine (TEA) adduct and converted to unsolvated alane by heating under vacuum. To complete the cycle, the starting alanate can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride (NaH) This novel reversible cycle opens the door for alane to fuel the hydrogen economy.

  9. Effects of metastability on hydrogen sorption in fluorine substituted hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Pinatel, E.R.; Corno, M.; Ugliengo, P.; Baricco, M., E-mail: marcello.baricco@unito.it

    2014-12-05

    Highlights: • Fluorine substitution in simple metal hydrides has been modelled. • The stability of the MH{sub (1−x)}F{sub x} solid solutions has been discussed. • Conditions for reversibility of sorption reactions have been suggested. - Abstract: In this work ab initio calculations and Calphad modelling have been coupled to describe the effect of fluorine substitution on the thermodynamics of hydrogenation–dehydrogenation in simple hydrides (NaH, AlH{sub 3} and CaH{sub 2}). These example systems have been used to discuss the conditions required for the formation of a stable hydride–fluoride solid solution necessary to obtain a reversible hydrogenation reaction.

  10. Modeling of hydrogen isotopes separation in a metal hydride bed

    International Nuclear Information System (INIS)

    Charton, S.; Corriou, J.P.; Schweich, D.

    1999-01-01

    A predictive model for hydrogen isotopes separation in a non-isothermal bed of unsupported palladium hydride particles is derived. It accounts for the non-linear adsorption-dissociation equilibrium, hydrodynamic dispersion, pressure drop, mass transfer kinetics, heat of sorption and heat losses at the bed wall. Using parameters from the literature or estimated with classical correlations, the model gives simulated curves in agreement with previously published experiments without any parameter fit. The non-isothermal behavior is shown to be responsible for drastic changes of the mass transfer rate which is controlled by diffusion in the solid-phase lattice. For a feed at 300 K and atmospheric pressure, the endothermic hydride-to-deuteride exchange is kinetically controlled, whereas the reverse exothermic exchange is nearly at equilibrium. Finally, a simple and efficient thermodynamic model for the dissociative equilibrium between a metal and a diatomic gas is proposed. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  11. Positronium hydride defects in thermochemically reduced alkaline-Earth oxides

    International Nuclear Information System (INIS)

    Monge, M.A.; Pareja, R.; Gonzalez, R.; Chen, Y.

    1997-01-01

    Thermochemical reduction of both hydrogen-doped MgO and CaO single crystals results in large concentrations of hydride (H - ) ions. In MgO crystals, positron lifetime and Doppler broadening experiments show that positrons are trapped at H - centers forming positronium hydride molecules [e + - H - ]. A value of 640 ps is obtained for the lifetime of the PsH states located in an anion vacancy In MgO positrons are also trapped at H 2- sites at low temperatures. The H 2- ions were induced in the crystals by blue light illumination. The formation of PsH states in CaO could not be conclusively established. (orig.)

  12. The Hall Effect in Hydrided Rare Earth Films

    Science.gov (United States)

    Koon, D. W.; Azofeifa, D. E.; Clark, N.

    We describe two new techniques for measuring the Hall effect in capped rare earth films during hydriding. In one, we simultaneously measure resistivity and the Hall coefficient for a rare earth film covered with four different thicknesses of Pd, recovering the charge transport quantities for both materials. In the second technique, we replace Pd with Mn as the covering layer. We will present results from both techniques.

  13. Photoelectron spectroscopic study of carbon aluminum hydride cluster anions

    Science.gov (United States)

    Zhang, Xinxing; Wang, Haopeng; Ganteför, Gerd; Eichhorn, Bryan W.; Kiran, Boggavarapu; Bowen, Kit H.

    2016-10-01

    Numerous previously unknown carbon aluminum hydride cluster anions were generated in the gas phase, identified by time-of-flight mass spectrometry and characterized by anion photoelectron spectroscopy, revealing their electronic structure. Density functional theory calculations on the CAl5-9H- and CAl5-7H2- found that several of them possess unusually high carbon atom coordination numbers. These cluster compositions have potential as the basis for new energetic materials.

  14. Synthesis and Hydrogen Desorption Properties of Aluminum Hydrides.

    Science.gov (United States)

    Jeong, Wanseop; Lee, Sang-Hwa; Kim, Jaeyong

    2016-03-01

    Aluminum hydride (AlH3 or alane) is known to store maximum 10.1 wt.% of hydrogen at relatively low temperature (aluminum. Our results show that the total amount of desorbed hydrogen from α-AlH3 exceeded 9.05 wt.%, with a possibility of further increase. Easy synthesis, thermal stability, and a large amount of hydrogen desorption of alane fulfill the requirements for light-weight hydrogen storage materials once the pathway of hydrogen cycling is provided.

  15. Thermomechanics of hydrogen storage in metallic hydrides: modeling and analysis

    Czech Academy of Sciences Publication Activity Database

    Roubíček, Tomáš; Tomassetti, G.

    2014-01-01

    Roč. 19, č. 7 (2014), s. 2313-2333 ISSN 1531-3492 R&D Projects: GA ČR GA201/09/0917 Institutional support: RVO:61388998 Keywords : metal-hydrid phase transformation * hydrogen diffusion * swelling Subject RIV: BA - General Mathematics Impact factor: 0.768, year: 2014 http://aimsciences.org/journals/pdfs.jsp?paperID=10195&mode=full

  16. Magnetization study of UNiSi and its hydride

    Czech Academy of Sciences Publication Activity Database

    Šebek, Josef; Andreev, Alexander V.; Honda, F.; Kolomiets, A. V.; Havela, L.; Sechovský, V.

    2003-01-01

    Roč. 34, č. 2 (2003), s. 1457-1460 ISSN 0587-4254. [International Conference on Strongly Correlated Electron Systems (SCES 02). Cracow, 10.07.2002-13.07.2002] R&D Projects: GA ČR GA202/02/0739 Institutional research plan: CEZ:AV0Z1010914; CEZ:MSM 113200002 Keywords : UNiSi * magnetic measurements * hydride Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.752, year: 2003

  17. Coated metal hydrides for stationary energy storage applications

    OpenAIRE

    Mistry, Priyen C.

    2016-01-01

    This thesis explores suitable materials for energy stores for stationary applications, specifically a prototype hydrogen store, domestic thermal store operating between 25-100 C and a moderate thermal store for a concentrated solar power (CSP) plant operating at 400 C. The approach incorporated a unique coating technique to deliver prototype hydrogen and thermal storage media, where the coating could offer commercial advantages, for example, in the form of hydride activation and enhanced kine...

  18. Testing setup for automatic cycling of metal hydride composites

    OpenAIRE

    Dieterich, Mila; Bürger, Inga; Linder, Marc Philipp

    2017-01-01

    In a future hydrogen community, metal hydrides can be used in several new applications. The most common application is as hydrogen storage material for stationary or mobile applications. However, there exist plenty of other applications like heat storage systems, thermal compressors, air conditioning systems, hydrogen purifying systems, etc. For all of these applications cycling stability is a major issue as it determines operational strategies as well as overall lifecycle cost. For pure m...

  19. Instrinsic defect energies of lithium hydride and lithium deuteride crystals

    International Nuclear Information System (INIS)

    Pandey, R.; Stoneham, A.M.

    1985-01-01

    A theoretical study has been made of the defect structure of lithium hydride and lithium deuteride. A potential model is obtained describing the statics and dynamics of these crystals. Intrinsic defect energies are calculated using the Harwell HADES program which is based on a generalised Mott-Littleton method. The results are in good agreement with the experimental data, and suggest that the vacancy and interstitial migration mechanisms of anions and cations are all comparable in their contribution to ionic conduction. (author)

  20. Equilibrium dissociation pressures of lithium hydride and lithium deuteride

    International Nuclear Information System (INIS)

    Smith, H.M.; Webb, R.E.

    1977-12-01

    The equilibrium dissociation pressures of plateau composition lithium hydride and lithium deuteride have been measured from 450 to 750 0 C. These data were used to derive the relationship of dissociation pressure with temperature over this range and to calculate several thermodynamic properties of these materials. Thermodynamic properties determined included the enthalpy, entropy, and free energy of formation; the enthalpy and entropy of fusion; and the melting points

  1. Optimization of hydride fueled pressurized water reactor cores

    International Nuclear Information System (INIS)

    Shuffler, Carter A.; Trant, Jarrod M.; Todreas, Neil E.

    2005-01-01

    Full text of publication follows: This paper reports the results of the thermal-hydraulic and economic analyses performed for hydride fueled PWR cores as part of a collaborative project on hydride fuels undertaken by MIT and UC Berkeley. The use of hydride fuels allows increased fuel to coolant ratios in a given core volume, and the achievement of higher burnups and thermal power from a core loading. A parametric study was developed to determine the optimum combination of lattice pitch, rod diameter, and channel shape - further referred to as geometry - for minimizing the cost of electricity associated with the use of UZrH 1.6 fuel in PWRs. Results of the steady-state and transient thermal hydraulic analyses are presented here. These are integrated with the results from fuel performance and neutronics studies into an economic model to reveal the desired optimal geometries. The thermal hydraulic analysis determines the maximum power that can be achieved for a given geometry, subject to steady-state and transient design constraints. Steady-state constraints include MDNBR, pressure drop, fuel temperature, and fuel rod vibrations. Transient constraints include the consideration of LOCA, LOFA, and over-power events. The fuel performance and neutronics analyses determine the maximum achievable burnup for a given geometry, subject to constraints on fuel internal pressure and fission gas release, clad oxidation, clad strain, and reactivity. All results are included in the economic model, which calculates the front and back end fuel cycle, operations and maintenance, and capital costs. Optimal designs include geometries where hydride fuel offers cost savings over oxide fuel, as well as geometries offering the lowest overall cost of electricity. All studies are performed for both UZrH 1.6 and UO 2 fuels, and the methodology is successfully validated by comparison of the predicted power, burnup, and cost of electricity for UO-2 fueled cores with corresponding data from

  2. Synthesis of Renewable Energy Materials, Sodium Aluminum Hydride by Grignard Reagent of Al

    OpenAIRE

    Jun-qin Wang; Jian-feng Gao; Zhi-gang Wu; Guo-li Ou; Yu Wang

    2015-01-01

    The research on hydrogen generation and application has attracted widespread attention around the world. This paper is to demonstrate that sodium aluminum hydride can be synthesized under simple and mild reaction condition. Being activated through organics, aluminum powder reacts with hydrogen and sodium hydride to produce sodium aluminum hydride under atmospheric pressure. The properties and composition of the sample were characterized by FTIR, XRD, SEM, and so forth. The results showed that...

  3. Long-term cycle stability of metal hydride-graphite composites

    OpenAIRE

    Dieterich, Mila; Pohlmann, Carsten; Bürger, Inga; Linder, Marc; Röntzsch, Lars

    2015-01-01

    Recently, metal hydride composites (MHC) have been proposed which consist of a hydride forming metal alloy and a highly heat conduction secondary phase such as expanded natural graphite (ENG) in order to improve the thermal conductivity of metal hydride powder beds. However, only little data is available in the literature on the effects of extensive cycling on technically relevant properties of MHC. In this paper, hydrogenation characteristics, thermal conductivity and geometrical stability o...

  4. Oxidation of Group 8 transition-Metal Hydrides and Ionic Hydrogenation of Ketones and Aldehydes

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Kjell-Tore

    1996-08-01

    Transition-metal hydrides have received considerable attention during the last decades because of their unusual reactivity and their potential as homogeneous catalysts for hydrogenation and other reactions of organic substrates. An important class of catalytic processes where transition-metal hydrides are involved is the homogeneous hydrogenation of alkenes, alkynes, ketones, aldehydes, arenes and nitro compounds. This thesis studies the oxidation of Group 8 transition-metal hydrides and the ionic hydrogenation of ketones and aldehydes.

  5. Metal hydride-based thermal energy storage systems

    Science.gov (United States)

    Vajo, John J.; Fang, Zhigang

    2017-10-03

    The invention provides a thermal energy storage system comprising a metal-containing first material with a thermal energy storage density of about 1300 kJ/kg to about 2200 kJ/kg based on hydrogenation; a metal-containing second material with a thermal energy storage density of about 200 kJ/kg to about 1000 kJ/kg based on hydrogenation; and a hydrogen conduit for reversibly transporting hydrogen between the first material and the second material. At a temperature of 20.degree. C. and in 1 hour, at least 90% of the metal is converted to the hydride. At a temperature of 0.degree. C. and in 1 hour, at least 90% of the metal hydride is converted to the metal and hydrogen. The disclosed metal hydride materials have a combination of thermodynamic energy storage densities and kinetic power capabilities that previously have not been demonstrated. This performance enables practical use of thermal energy storage systems for electric vehicle heating and cooling.

  6. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    International Nuclear Information System (INIS)

    Totemeier, T.C.; Pahl, R.G.; Frank, S.M.

    1998-01-01

    The oxidation behavior of hydride-bearing uranium metal corrosion products from zero power physics reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2 , Ar-9%O 2 , and Ar-20%O 2 . Ignition of corrosion product samples from two moderately corroded plates was observed between 125 C and 150 C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride. (orig.)

  7. The effect of sample preparation on uranium hydriding

    International Nuclear Information System (INIS)

    Banos, A.; Stitt, C.A.; Scott, T.B.

    2016-01-01

    Highlights: • Distinct differences in uranium hydride growth rates and characteristics between different surface preparation methods. • The primary difference between the categories of sample preparations is the level of strain present in the surface. • Greater surface-strain, leads to higher nucleation number density, implying a preferred attack of strained vs unstrained metal. • As strain is reduced, surface features such as carbides and grain boundaries become more important in controlling the UH3 location. - Abstract: The influence of sample cleaning preparation on the early stages of uranium hydriding has been examined, by using four identical samples but concurrently prepared using four different methods. The samples were reacted together in the same corrosion cell to ensure identical exposure conditions. From the analysis, it was found that the hydride nucleation rate was proportional to the level of strain exhibiting higher number density for the more strained surfaces. Additionally, microstructure of the metal plays a secondary role regarding initial hydrogen attack on the highly strained surfaces yet starts to dominate the system while moving to more pristine samples.

  8. A thermal neutron scattering law for yttrium hydride

    Science.gov (United States)

    Zerkle, Michael; Holmes, Jesse

    2017-09-01

    Yttrium hydride (YH2) is of interest as a high temperature moderator material because of its superior ability to retain hydrogen at elevated temperatures. Thermal neutron scattering laws for hydrogen bound in yttrium hydride (H-YH2) and yttrium bound in yttrium hydride (Y-YH2) prepared using the ab initio approach are presented. Density functional theory, incorporating the generalized gradient approximation (GGA) for the exchange-correlation energy, is used to simulate the face-centered cubic structure of YH2 and calculate the interatomic Hellmann-Feynman forces for a 2 × 2 × 2 supercell containing 96 atoms. Lattice dynamics calculations using PHONON are then used to determine the phonon dispersion relations and density of states. The calculated phonon density of states for H and Y in YH2 are used to prepare H-YH2 and Y-YH2 thermal scattering laws using the LEAPR module of NJOY2012. Analysis of the resulting integral and differential scattering cross sections demonstrates adequate resolution of the S(α,β) function. Comparison of experimental lattice constant, heat capacity, inelastic neutron scattering spectra and total scattering cross section measurements to calculated values are used to validate the thermal scattering laws.

  9. A thermal neutron scattering law for yttrium hydride

    Directory of Open Access Journals (Sweden)

    Zerkle Michael

    2017-01-01

    Full Text Available Yttrium hydride (YH2 is of interest as a high temperature moderator material because of its superior ability to retain hydrogen at elevated temperatures. Thermal neutron scattering laws for hydrogen bound in yttrium hydride (H-YH2 and yttrium bound in yttrium hydride (Y-YH2 prepared using the ab initio approach are presented. Density functional theory, incorporating the generalized gradient approximation (GGA for the exchange-correlation energy, is used to simulate the face-centered cubic structure of YH2 and calculate the interatomic Hellmann-Feynman forces for a 2 × 2 × 2 supercell containing 96 atoms. Lattice dynamics calculations using PHONON are then used to determine the phonon dispersion relations and density of states. The calculated phonon density of states for H and Y in YH2 are used to prepare H-YH2 and Y-YH2 thermal scattering laws using the LEAPR module of NJOY2012. Analysis of the resulting integral and differential scattering cross sections demonstrates adequate resolution of the S(α,β function. Comparison of experimental lattice constant, heat capacity, inelastic neutron scattering spectra and total scattering cross section measurements to calculated values are used to validate the thermal scattering laws.

  10. Autocatalytic effects in the mechanically induced hydriding of refractory metals

    International Nuclear Information System (INIS)

    Bab, M.A.; Baum, L.A.; Mendoza-Zelis, L.

    2007-01-01

    Mechanical milling of powders in a gaseous ambient is an efficient tool to induce gas-solid reactions and several nanocrystalline metallic oxides, nitrides and hydrides may be obtained at room temperature and moderated pressures by this route. We present here a study of the mechanically induced hydriding of Ti, Zr and Hf elemental powders, ground in an oscillatory mill under hydrogen gas at constant volume. The final formation of nanocrystalline cubic δ-MH 2 , together with a varying fraction of tetragonal ε-MH 2 , was verified by X-ray diffraction. From the measured pressure drop during the milling process the hydriding kinetics was determined and two distinct regimes were observed. For Ti and-at low milling frequencies-for Zr and Hf, a normal regime, characterized by a sigmoidal trend and a linear dependence of the rate constant on the milling intensity, was found. Otherwise, a sudden increase in the reacted fraction was observed in the absorption curve, typical of a self-sustained regime. The magnitude of the observed jump increases with the milling intensity and afterwards the reaction proceeds normally until it is completed. This critical behavior is discussed in terms of the reaction rate, the degree of transformation and the ε-phase content

  11. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    Science.gov (United States)

    Totemeier, Terry C.; Pahl, Robert G.; Frank, Steven M.

    The oxidation behavior of hydride-bearing uranium metal corrosion products from Zero Power Physics Reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2, Ar-9%O 2, and Ar-20%O 2. Ignition of corrosion product samples from two moderately corroded plates was observed between 125°C and 150°C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride.

  12. Synthesis of Renewable Energy Materials, Sodium Aluminum Hydride by Grignard Reagent of Al

    Directory of Open Access Journals (Sweden)

    Jun-qin Wang

    2015-01-01

    Full Text Available The research on hydrogen generation and application has attracted widespread attention around the world. This paper is to demonstrate that sodium aluminum hydride can be synthesized under simple and mild reaction condition. Being activated through organics, aluminum powder reacts with hydrogen and sodium hydride to produce sodium aluminum hydride under atmospheric pressure. The properties and composition of the sample were characterized by FTIR, XRD, SEM, and so forth. The results showed that the product through this synthesis method is sodium aluminum hydride, and it has higher purity, perfect crystal character, better stability, and good hydrogen storage property. The reaction mechanism is also discussed in detail.

  13. Hydrogen storage and evolution catalysed by metal hydride complexes.

    Science.gov (United States)

    Fukuzumi, Shunichi; Suenobu, Tomoyoshi

    2013-01-07

    The storage and evolution of hydrogen are catalysed by appropriate metal hydride complexes. Hydrogenation of carbon dioxide by hydrogen is catalysed by a [C,N] cyclometalated organoiridium complex, [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(OH(2))](2)SO(4) [Ir-OH(2)](2)SO(4), under atmospheric pressure of H(2) and CO(2) in weakly basic water (pH 7.5) at room temperature. The reverse reaction, i.e., hydrogen evolution from formate, is also catalysed by [Ir-OH(2)](+) in acidic water (pH 2.8) at room temperature. Thus, interconversion between hydrogen and formic acid in water at ambient temperature and pressure has been achieved by using [Ir-OH(2)](+) as an efficient catalyst in both directions depending on pH. The Ir complex [Ir-OH(2)](+) also catalyses regioselective hydrogenation of the oxidised form of β-nicotinamide adenine dinucleotide (NAD(+)) to produce the 1,4-reduced form (NADH) under atmospheric pressure of H(2) at room temperature in weakly basic water. In weakly acidic water, the complex [Ir-OH(2)](+) also catalyses the reverse reaction, i.e., hydrogen evolution from NADH to produce NAD(+) at room temperature. Thus, interconversion between NADH (and H(+)) and NAD(+) (and H(2)) has also been achieved by using [Ir-OH(2)](+) as an efficient catalyst and by changing pH. The iridium hydride complex formed by the reduction of [Ir-OH(2)](+) by H(2) and NADH is responsible for the hydrogen evolution. Photoirradiation (λ > 330 nm) of an aqueous solution of the Ir-hydride complex produced by the reduction of [Ir-OH(2)](+) with alcohols resulted in the quantitative conversion to a unique [C,C] cyclometalated Ir-hydride complex, which can catalyse hydrogen evolution from alcohols in a basic aqueous solution (pH 11.9). The catalytic mechanisms of the hydrogen storage and evolution are discussed by focusing on the reactivity of Ir-hydride complexes.

  14. Hydride phase equilibria in V-Ti-Ni alloy membranes

    Energy Technology Data Exchange (ETDEWEB)

    Dolan, Michael D., E-mail: michael.dolan@csiro.au [CSIRO Energy, Pullenvale, Queensland (Australia); Kochanek, Mark A.; Munnings, Christopher N. [CSIRO Energy, Pullenvale, Queensland (Australia); McLennan, Keith G. [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Queensland (Australia); Viano, David M. [CSIRO Energy, Pullenvale, Queensland (Australia)

    2015-02-15

    Highlights: • V{sub 70}Ti{sub 15}Ni{sub 15} (at.%) comprises a vanadium solid solution plus NiTi and NiTi{sub 2}. • Dissolution of Ni and Ti into vanadium solid solution increase critical temperature for BCT β-hydride formation. • Three V{sub SS} hydride phase fields were observed: BCC, BCC + BCT, BCT + BCT. • NiTi and NiTi{sub 2} phases do not stabilise the alloy against brittle failure. - Abstract: Vanadium is highly permeable to hydrogen which makes it one of the leading alternatives to Pd alloys for hydrogen-selective alloy membrane applications, but it is prone to brittle failure through excessive hydrogen absorption and transitions between the BCC α and BCT β phases. V-Ti-Ni alloys are a prospective class of alloy for hydrogen-selective membrane applications, comprising a highly-permeable vanadium solid solution and several interdendritic Ni-Ti compounds. These Ni-Ti compounds are thought to stabilise the alloy against brittle failure. This hypothesis was investigated through a systematic study of V{sub 70}Ti{sub 15}Ni{sub 15} by hydrogen absorption and X-ray diffraction under conditions relevant to membrane operation. Dissolved hydrogen concentration in the bulk alloy and component phases, phase identification, thermal and hydrogen-induced expansion, phase quantification and hydride phase transitions under a range of pressures and temperatures have been determined. The vanadium phase passes through three different phase fields (BCC, BCC + BCT, BCT + BCT) during cooling under H{sub 2} from 400 to 30 °C. Dissolution of Ni and Ti into the vanadium phase increases the critical temperature for β-hydride formation from <200 to >400 °C. Furthermore, the Ni-Ti phases also exhibit several phase transitions meaning their ability to stabilise the alloy is questionable. We conclude that this alloy is significantly inferior to V with respect to its stability when used as a hydrogen-selective membrane, but the hydride phase transitions suggest potential

  15. Reactivity patterns of transition metal hydrides and alkyls

    International Nuclear Information System (INIS)

    Jones, W.D. II.

    1979-05-01

    The complex PPN + CpV(CO) 3 H - (Cp=eta 5 -C 5 H 5 and PPN = (Ph 3 P) 2 ) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN + CpV(CO) 3 H - reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN + [CpV(C) 3 X] - and in some cases the binuclear bridging hydride PPN + [CpV(CO) 3 ] 2 H - . The borohydride salt PPN + [CpV(CO) 3 BH 4 ] - has also been prepared. The reaction between CpV(CO) 3 H - and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO) 3 H - . Sodium amalgam reduction of CpRh(CO) 2 or a mixture of CpRh(CO) 2 and CpCo(CO) 2 affords two new anions, PPN + [Cp 2 Rh 3 (CO) 4 ] - and PPN + [Cp 2 RhCo(CO) 2 ] - . CpMo(CO) 3 H reacts with CpMo(CO) 3 R (R=CH 3 ,C 2 H 5 , CH 2 C 6 H 5 ) at 25 to 50 0 C to produce aldehyde RCHO and the dimers [CpMo(CO) 3 ] 2 and [CpMo(CO) 2 ] 2 . In general, CpV(CO) 3 H - appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO) 3 H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO) 3 H - generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO) 3 H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species

  16. Development and evaluation of a hydride technique for As, Sb, and Se determinations by inductively coupled plasma-atomic emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sloat, Sharon Sue [Iowa State Univ., Ames, IA (United States)

    1977-10-01

    A literature review of hydride techniques, experimental facilities, development and evaluation of a hydride technique, and interelement effects are covered. Suggestions for future work are given. (LK)

  17. Effects of chemesthetic stimuli mixtures with barium on swallowing apnea duration.

    Science.gov (United States)

    Todd, J Tee; Butler, Susan G; Plonk, Drew P; Grace-Martin, Karen; Pelletier, Cathy A

    2012-10-01

    This study tested the hypotheses that swallowing apnea duration (SAD) will increase given barium versus water, chemesthetic stimuli (i.e., water barium, age (older > younger), and genetic taste differences (supertasters > nontasters). Prospective group design. University Medical Center. Eighty healthy women were identified as nontasters and supertasters, equally comprising two age groups: 18 to 35 years and 60+ years. The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL barium, 2.7% w/v citric acid with barium, carbonation with barium, and 50:50 diluted ethanol with barium. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures. Significant main effects of age (P = .012) and chemesthetic stimuli (P = .014) were found, as well as a significant interaction between chemesthetic stimuli and age (P = .028). Older women had a significantly longer SAD than younger women. Post hoc analyses revealed that barium mixed with ethanol elicited a significantly longer SAD than other bolus conditions, regardless of age group. There were no significant differences in SAD between barium and water conditions, and no significant effect of chemesthetic perception (P > .05). Ethanol added to barium elicited longer SAD compared to plain barium, but not the other chemesthetic conditions. Older women had a longer SAD than younger women in all conditions. These findings may influence design of future studies examining effects of various stimuli on SAD. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

  18. Exposure to low-dose barium by drinking water causes hearing loss in mice.

    Science.gov (United States)

    Ohgami, Nobutaka; Hori, Sohjiro; Ohgami, Kyoko; Tamura, Haruka; Tsuzuki, Toyonori; Ohnuma, Shoko; Kato, Masashi

    2012-10-01

    We continuously ingest barium as a general element by drinking water and foods in our daily life. Exposure to high-dose barium (>100mg/kg/day) has been shown to cause physiological impairments. Direct administration of barium to inner ears by vascular perfusion has been shown to cause physiological impairments in inner ears. However, the toxic influence of oral exposure to low-dose barium on hearing levels has not been clarified in vivo. We analyzed the toxic influence of oral exposure to low-dose barium on hearing levels and inner ears in mice. We orally administered barium at low doses of 0.14 and 1.4 mg/kg/day to wild-type ICR mice by drinking water. The doses are equivalent to and 10-fold higher than the limit level (0.7 mg/l) of WHO health-based guidelines for drinking water, respectively. After 2-week exposure, hearing levels were measured by auditory brain stem responses and inner ears were morphologically analyzed. After 2-month exposure, tissue distribution of barium was measured by inductively coupled plasma mass spectrometry. Low-dose barium in drinking water caused severe hearing loss in mice. Inner ears including inner and outer hair cells, stria vascularis and spiral ganglion neurons showed severe degeneration. The Barium-administered group showed significantly higher levels of barium in inner ears than those in the control group, while barium levels in bone did not show a significant difference between the two groups. Barium levels in other tissues including the cerebrum, cerebellum, heart, liver and kidney were undetectably low in both groups. Our results demonstrate for the first time that low-dose barium administered by drinking water specifically distributes to inner ears resulting in severe ototoxicity with degeneration of inner ears in mice. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Regeneration of barium carbonate from barium sulphide in a pilot-scale bubbling column reactor and utilization for acid mine drainage

    CSIR Research Space (South Africa)

    Mulopo, J

    2012-01-01

    Full Text Available Batch regeneration of barium carbonate (BaCO3) from barium sulphide (BaS) slurries by passing CO2 gas into a pilot-scale bubbling column reactor under ambient conditions was used to assess the technical feasibility of BaCO3 recovery in the Alkali...

  20. Gas thermodesorption study of barium and strontium cerates

    International Nuclear Information System (INIS)

    Aksenova, T.I.; Khromushin, I.V.; Zhotabaev, Zh.R.; Bukenov, K.D.; Medvedeva, Z.V.; Berdauletov, A.K.

    2002-01-01

    Kinetic of water, oxygen, hydrogen and carbon dioxide molecules release from doped and undoped samples of barium cerates and doped strontium cerates during vacuum heating was studied. The samples were prepared by inductive melting method. The following two kinds of preliminary samples treatments were used: annealing in air (650-750 deg. C) and wet nitrogen atmosphere (625 deg.C). Main results of thermodesorption studies of barium and strontium cerates are represented in the table. The samples of doped LaSrMnO were investigated also. It was found that the initial doped samples (without preliminary annealing) did not show any gas release in temperature range of 20-1100 deg. C. This fact indicates on high stability of compositions and strong bond of 'host' oxygen in their lattice. A significant amount of water and oxygen molecules were released from BaCe 0.9 Nd 0.1 O 3 samples whereas water and hydrogen molecules desorption from SrCe 0.95 Y 0.05 O 3 samples took place. Hydrogen molecules desorption was found for strontium cerates samples; no hydrogen molecules release was observed for doped and pure barium cerate samples.Intensive water molecules release from doped samples confirms the necessity of oxygen vacancies creation in these compounds to get properties of proton conductivity, since it was not found any water molecules release from annealed undoped samples of BaCeO 3 It is necessary to notice that oxygen molecules release from these samples took place at ∼1000 deg. C that is significantly higher then from BaCeNdO samples. Forms of high temperatures part of oxygen and low temperature part of water spectra indicate that phase transformations are responsible for oxygen and water molecules desorption in this cases. These results are in good agreement with literature data. Desorption of water molecules from barium and strontium cerates took place. Oxygen desorption took place only from barium cerates. It can be explained as the following: doped barium cerates have

  1. Low-Cost Metal Hydride Thermal Energy Storage System for Concentrating Solar Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zidan, Ragaiy [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hardy, B. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Corgnale, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Teprovich, J. A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Ward, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Motyka, Ted [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-01-31

    The objective of this research was to evaluate and demonstrate a metal hydride-based TES system for use with a CSP system. A unique approach has been applied to this project that combines our modeling experience with the extensive material knowledge and expertise at both SRNL and Curtin University (CU). Because of their high energy capacity and reasonable kinetics many metal hydride systems can be charged rapidly. Metal hydrides for vehicle applications have demonstrated charging rates in minutes and tens of minutes as opposed to hours. This coupled with high heat of reaction allows metal hydride TES systems to produce very high thermal power rates (approx. 1kW per 6-8 kg of material). A major objective of this work is to evaluate some of the new metal hydride materials that have recently become available. A problem with metal hydride TES systems in the past has been selecting a suitable high capacity low temperature metal hydride material to pair with the high temperature material. A unique aspect of metal hydride TES systems is that many of these systems can be located on or near dish/engine collectors due to their high thermal capacity and small size. The primary objective of this work is to develop a high enthalpy metal hydride that is capable of reversibly storing hydrogen at high temperatures (> 650 °C) and that can be paired with a suitable low enthalpy metal hydride with low cost materials. Furthermore, a demonstration of hydrogen cycling between the two hydride beds is desired.

  2. Barium determination in gastric contents, blood and urine by inductively coupled plasma mass spectrometry in the case of oral barium chloride poisoning.

    Science.gov (United States)

    Łukasik-Głębocka, Magdalena; Sommerfeld, Karina; Hanć, Anetta; Grzegorowski, Adam; Barałkiewicz, Danuta; Gaca, Michał; Zielińska-Psuja, Barbara

    2014-01-01

    A serious case of barium intoxication from suicidal ingestion is reported. Oral barium chloride poisoning with hypokalemia, neuromuscular and cardiac toxicity, treated with intravenous potassium supplementation and hemodialysis, was confirmed by the determination of barium concentrations in gastric contents, blood, serum and urine using the inductively coupled plasma mass spectrometry method. Barium concentrations in the analyzed specimens were 20.45 µg/L in serum, 150 µg/L in blood, 10,500 µg/L in urine and 63,500 µg/L in gastric contents. Results were compared with barium levels obtained from a non-intoxicated person. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Perforated colorectal neoplasms: Correlation of clinical, barium, and CT examinations

    International Nuclear Information System (INIS)

    Hulnick, D.H.; Megibow, A.J.; Gordon, R.; Balthazar, E.J.

    1986-01-01

    Findings on clinical, barium enema, and CT examinations in 24 patients with perforated colorectal neoplasms were retrospectively reviewed. In 12 patients with fever and leukocytosis, the clinical diagnoses were diverticulitis (n=8), appendicitis (n=2), pelvic inflammatory disease (n=2), and perforation of a known carcinoma (n=1). In 12 nontoxic patients, the clinical diagnoses were malignancy (n=8), obstruction (n=3) and an abdominal mass (n=1). In 18 barium enema examinations, the radiologic impression was uncomplicated carcinoma (n=9), perforated carcinoma (n=6), and diverticulitis (n=3). Twenty-two CT examinations revealed pericolic inflammation in all cases and macroperforation in 12. The primary tumor was evident in 14 patients, liver metastases were found in six, and ascites was present in three. CT findings influenced the management of patients initially suspected of having inflammatory conditions

  4. Electromagnetic properties of photodefinable barium ferrite polymer composites

    Directory of Open Access Journals (Sweden)

    Olusegun Sholiyi

    2014-07-01

    Full Text Available This article reports the magnetic and microwave properties of a Barium ferrite powder suspended in a polymer matrix. The sizes for Barium hexaferrite powder are 3–6 μm for coarse and 0.8–1.0 μm for the fine powder. Ratios 1:1 and 3:1 (by mass of ferrite to SU8 samples were characterized and analyzed for predicting the necessary combinations of these powders with SU8 2000 Negative photoresist. The magnetization properties of these materials were equally determined and were analyzed using Vibrating Sample Magnetometer (VSM. The Thru, Reflect, Line (TRL calibration technique was employed in determining complex relative permittivity and permeability of the powders and composites with SU8 between 26.5 and 40 GHz.

  5. Influence of Magnetron Effect on Barium Hexaferrite Thin Layers

    International Nuclear Information System (INIS)

    Hassane, H.; Chatelon, J.P.; Rousseau, J.J; Siblini, A.; Kriga, A.

    2011-01-01

    In this paper, we study the effects of a magnet, located in the cathode, on barium hexaferrite thin films deposited by RF magnetron sputtering technique. During the process, these effects can modify thickness, roughness and stress of coatings. The characteristics of the deposited layers depend on the substrate position that is located opposite of magnetron cathode. In the m agnetron area , one can observe that the high stress can produce cracks or detachment of layers and the increasing of both depositing rate and surface roughness. After sputtering elaboration, barium hexaferrite films are in a compressive stress mode. But, after the post-deposition heat treatment these films are in a tensile stress mode. To improve the quality of BaM films, the subsrtate has to be set outside the magnetron area. (author)

  6. Synthesis of Barium Titanate Piezoelectric Ceramics for Multilayer Actuators (MLAs

    Directory of Open Access Journals (Sweden)

    Biglar Mojtaba

    2017-12-01

    Full Text Available In this paper the characteristics of BaTiO3 ceramics synthesized by solid state method is presented. In order to receive the monophase ceramics the double activation and calcination were applied. A spray drier was used to granulate the powder of BaTiO3. Isostatic and uniaxial pressing were applied to manufacture the barium titanate pellets. The properties of fabricated BaTiO3 ceramics were determined at different stages of production. After the sintering phase, the hardness, the bending strength, the fracture toughness, and the coefficient of thermal expansion of barium titanate sinter were estimated. The BaTiO3 powder is characterized by spherical grains and the average size of 0.5 μm. The small value of the specific surface area of granulate ensured good properties of material mouldability and finally allowed to receive sinters of high density.

  7. Barium titanate nanoparticles: promising multitasking vectors in nanomedicine.

    Science.gov (United States)

    Genchi, Giada Graziana; Marino, Attilio; Rocca, Antonella; Mattoli, Virgilio; Ciofani, Gianni

    2016-06-10

    Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these 'smart' nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation.

  8. Attainment of barium hexaferrite nanoparticles by a Pechini Method

    International Nuclear Information System (INIS)

    Galvao, S.B.; Timoteo, Jr.J.F.; Melo, G.M.; Souto, K.K.O.; Florioto, N.T.; Paskocimas, C.A.

    2009-01-01

    The barium hexaferrites (BaFe 12 O 19 ) are used as a compound of materials applied in electronic devices, as medical devices, satellites, dada servers systems, wireless systems and others. The general properties are strongly related to the microstructure and morphology, and the particles size decrease results in advantages to the majority applications, mainly the high-tech thumbnail devices. These magnetic ceramic materials, with perovskite structure, are traditionally prepared my conventional oxide mixture synthesis. In this work was studied the nanoparticle synthesis of BaFe 12 O 19 by the precursors polymeric method (Pechini), using as precursors the barium carbonate and the iron nitrate, under different thermal treatment conditions. The samples were characterized by XRD, SEM, BET, DTA and TGA. The results presented the attainment of a monophasic powder with particles size around 100 nm. (author)

  9. Combined on-board hydride slurry storage and reactor system and process for hydrogen-powered vehicles and devices

    Science.gov (United States)

    Brooks, Kriston P; Holladay, Jamelyn D; Simmons, Kevin L; Herling, Darrell R

    2014-11-18

    An on-board hydride storage system and process are described. The system includes a slurry storage system that includes a slurry reactor and a variable concentration slurry. In one preferred configuration, the storage system stores a slurry containing a hydride storage material in a carrier fluid at a first concentration of hydride solids. The slurry reactor receives the slurry containing a second concentration of the hydride storage material and releases hydrogen as a fuel to hydrogen-power devices and vehicles.

  10. Barium fluoride surface preparation, analysis and UV reflective coatings at Lawrence Livermore National Laboratory

    International Nuclear Information System (INIS)

    Wuest, C.R.

    1992-01-01

    Lawrence Livermore National Laboratory (LLNL) has begun a program of study on barium fluoride scintillating crystals for the Barium Fluoride Electromagnetic Calorimeter Collaboration. This program has resulted in a number of significant improvements in the mechanical processing, polishing and coating of barium fluoride crystals. Techniques have been developed using diamond-loaded pitch lapping that can produce 15 angstrom RMS surface finishes over large areas. These lapped surfaces have been shown to be crystalline using Rutherford Back-scattering (RBS). Also, special polishing fixtures have been designed based on mounting technology developed for the 1.1 m diameter optics used in LLNL's Nova Laser. These fixtures allow as many as five 25--50 cm long barium fluoride crystals to be polished and lapped at a time with the necessary tolerances for the 16,000 crystal Barium Fluoride Calorimeter. In addition, results will be presented on coating barium fluoride with UV reflective layers of magnesium fluoride and aluminum

  11. Vanadium doped barium germanate microrods and photocatalytic properties under solar light

    Science.gov (United States)

    Pei, L. Z.; Wang, S.; Liu, H. D.; Lin, N.; Yu, H. Y.

    2015-01-01

    Vanadium doped barium germanate microrods have been prepared by a facile hydrothermal process. The obtained vanadium doped barium germanate microrods are proved to be hexagonal BaGe4O9 and orthorhombic Ba2V2O7 phases by X-ray diffraction. Scanning electron microscopy shows that the vanadium doped barium germanate products consist of microrods with the diameter of microscale size. The diameter of the mirorods decreases from 800 nm to 150 nm with the vanadium doping mass percentage increasing from 1% to 10%. Solid UV-vis diffuse reflectance spectra show that the band gap of the vanadium doped barium germanate is smaller than that of the undoped barium germanate. The photocatalytic activity has been greatly enhanced by the vanadium doping. The vanadium doped barium germanate microrods exhibit great application potential for the photocatalytic degradation of methylene blue under solar light irradiation.

  12. Clinical efficacy of a new barium sulfate for abdominal CT

    International Nuclear Information System (INIS)

    Yamada, Tatuya; Kohno, Mitio; Uematsu, Sadao; Nisitani, Hiromu; Tanaka, Takao.

    1988-01-01

    Computed Tomography of the abdomen requires that the intestines are filled with contrast medium so that the gut is not misinterpreted as a pathologic process. Besides, normal structures may be difficult to delimit in patients with scanty intra-abdominal fat. In Japan, up to date, only a single contrast medium has been available for this purpose, Gastrografin and thus identical with the intravasculaly used Urografin or Angiografin. A new Barium Sulfate suspention (Fusimi Seiyaku, Kagawa) for computed tomographic use has been dilute solution (4.77 %) and with suspending agents that prevent a rapid sedimentation of the Barium Sulfate. The aim of this investigation was to compare Gastrografin with a new barium regarding patients tolerance, side effects and diagnostic information. The investigation comprised 146 patients who were reffered for abdominal CT and was carried out by 5 facilities; National Cancer Center, Kobe University, Chiba University, Kyushu University and Juntendo University. Diagnostic information was judged with respect to the filling of the stomach and intestines, the presence of imaging artifacts and finally clinical estimation. Patients tolerance was investigated as regards taste and side effects. Good filling of the stomach and intestines was obtained in this investigation. However, imaging artifacts occured in only a few cases. The imaging artifacts appeared almost exclusively to arise in the boundary layer between the bowel gas and contrast medium, and were most common in the stomach. However, the contrasting effect of this medium did not in itself appear to cause any imaging artifacts. Fushimi's new barium seems to be preffered because of its lesser tendency to arise artifacts and better tendency to make good filling of the stomach and intestines. Moreover, this investigation did not have any side effects. (J.P.N.)

  13. Optical and luminescent properties of the lead and barium molybdates

    Energy Technology Data Exchange (ETDEWEB)

    Spassky, D.A. E-mail: dima@opts.phys.msu.ru; Ivanov, S.N.; Kolobanov, V.N.; Mikhailin, V.V.; Zemskov, V.N.; Zadneprovski, B.I.; Potkin, L.I

    2004-12-01

    Time-resolved luminescence as well as excitation and reflectivity spectra of the oriented lead and barium molybdate single crystals were studied using synchrotron radiation. Features in reflectivity spectra in the fundamental absorption region were analyzed. The contribution of electronic states of lead cation to the formation of the bandgap in PbMoO{sub 4} is supposed. The role of lead states in the intrinsic luminescence of PbMoO{sub 4} is discussed.

  14. Sulphate removal from industrial effluents through barium sulphate precipitation

    CSIR Research Space (South Africa)

    Swanepoel, H

    2011-11-01

    Full Text Available surface wetland g Gas HiPRO Hi recovery Precipitating Reverse Osmosis l Liquid MBO Magnesium Barium Oxide ORP Oxidation-reduction potential RO Reverse osmosis s Solid SANAS South African National Accreditation System SANS... South African National Standards SEM Scanning electron microscopy SF wetland Subsurface flow wetland SPARRO Slurry precipitation and recycle reverse osmosis SRO Seeded reverse osmosis TDS Total Dissolved Solids WHO World Health...

  15. Structure and multiferroic properties of barium hexaferrite ceramics

    International Nuclear Information System (INIS)

    Tan, Guolong; Chen, Xiuna

    2013-01-01

    Simultaneous occurrence of large ferroelectricity and strong ferromagnetism have been observed in barium hexaferrite ceramics. Barium hexaferrite (BaFe 12 O 19 ) powders with hexagonal crystal structure were successfully synthesized in a polymer precursor method using barium acetate and ferric acetylacetonate as the precursors. The powders were pressed into pellets which were sintered into ceramics at 1200 °C and 1300 °C for 1 h. The structure and morphology of the ceramics were examined using X-ray diffraction and field emission scanning electron microscopy. Large spontaneous polarization was observed in the BaFe 12 O 19 ceramics at room temperature, revealing a clear ferroelectric hysteresis loop. The maximum remanent polarization of the BaFe 12 O 19 ceramic was estimated approximately 11.8 μC cm −2 . The FeO 6 octahedron in its perovskite-like hexagonal unit cell and the shift of Fe 3+ off the center of octahedron are suggested to be the origin of the polarization in BaFe 12 O 19 . The BaFe 12 O 19 ceramics also showed strong ferromagnetism at room temperature. - Graphical abstract: Ferroelectric hysteresis loops of BaFe 12 O 19 ceramics measured at a frequency of 120 Hz, which shows that the ceramics sintered at 1200 °C is ferroelectric with P r ∼11.8 μC/cm 2 . Highlights: ► Large ferroelectricity and strong ferromagnetism were observed in barium hexaferrite ceramics. ► The maximum remanent polarization of the BaFe 12 O 19 ceramic was estimated to be 11.8 μC cm −2 . ► The FeO 6 octahedron and off-center shift of Fe 3+ are suggested to be the origin of the polarization.

  16. Preparation of barium and uranium targets on thick backings

    International Nuclear Information System (INIS)

    Sletten, G.

    1982-01-01

    Targets of 135 Ba and 235 U have been prepared by the technique of heavy ion sputtering. Rolled foils of 208 Pb and 197 Au were used to support 250-500 μg/cm 2 layers of barium. Uranium films have been prepared by sputtering UO 2 onto 1 mg/cm 2 titanium foils. Uranium deposit thicknesses of 300 to 1800 μg/cm 2 have been prepared. (orig.)

  17. Hydrogen storage material and process using graphite additive with metal-doped complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy [Aiken, SC; Ritter, James A [Lexington, SC; Ebner, Armin D [Lexington, SC; Wang, Jun [Columbia, SC; Holland, Charles E [Cayce, SC

    2008-06-10

    A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

  18. Silicon nanowires as a rechargeable template for hydride transfer in redox biocatalysis

    Science.gov (United States)

    Lee, Hwa Young; Kim, Jae Hong; Son, Eun Jin; Park, Chan Beum

    2012-11-01

    We report a new possible application of hydrogen-terminated silicon nanowires (H-SiNWs) as a rechargeable template for hydride transfer in redox biocatalysis. H-SiNWs transfer hydride efficiently to regenerate NADH by oxidizing Si-Hx bonds. The oxidized H-SiNWs were readily recharged for the continuous regeneration of NADH and enzymatic reactions.

  19. Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

    Czech Academy of Sciences Publication Activity Database

    D'Ulivo, A.; Dědina, Jiří; Mester, Z.; Sturgeon, R. E.; Wang, Q.; Welz, B.

    2011-01-01

    Roč. 83, č. 6 (2011), s. 1283-1340 ISSN 0033-4545 Institutional research plan: CEZ:AV0Z40310501 Keywords : borane complexes * chemical generation of volatile hydrides (CHG) * volatile hydrides Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.789, year: 2011

  20. Experimental comparison on heat transfer-enhancing component of metal hydride bed

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hyun-goo, E-mail: hgkang@nfri.re.kr; Chung, Dong-you; Oh, Yun Hee; Chang, Min Ho; Yun, Sei-Hun

    2016-11-01

    Highlights: • Two small ZrCo metal hydride beds were developed. • Copper foam or fin as heat transfer-enhancing component are experimentally compared. • Copper foam bed is more efficient for uniform and rapid heating of metal hydride. • Copper foam bed is more efficient in removal of reaction heat during absorption. - Abstract: Metal hydride bed will be one of the key components for safe handling of tritium in fusion fuel cycle. In case of normal or emergency shutdown of fuel cycle, metal hydride bed installed in storage and delivery system (SDS) of tritium plant will absorb tritium gas in the system as soon as possible. Supply of hydrogen isotope gas to fueling system of fusion reactor will start from the metal hydride beds. Rapid delivery, rapid recovery including rapid heating and cooling are key issues. For better performance of metal hydride bed, various forms of heat transfer enhancing component or design can be applied. This study aims to help the selection of heat transfer enhancing component. Two small ZrCo beds with copper foam and copper fin were developed and experimented with hydrogen gas. Recovery and delivery performance, heating and cooling performance are compared. Experimental results show metal hydride bed with copper foam has improved performance. Uniform heating of metal hydride during desorption and removal of reaction heat during absorption are more efficient with copper foam bed than copper fin bed.

  1. Hydride precipitation crack propagation in zircaloy cladding during a decreasing temperature history

    International Nuclear Information System (INIS)

    Stout, R.B.

    2001-01-01

    An assessment of safety, design, and cost tradeoff issues for short (ten to fifty years) and longer (fifty to hundreds of years) interim dry storage of spent nuclear fuel in Zircaloy rods shall address potential failures of the Zircaloy cladding caused by the precipitation response of zirconium hydride platelets. To perform such assessment analyses rigorously and conservatively will be necessarily complex and difficult. For Zircaloy cladding, a model for zirconium hydride induced crack propagation velocity was developed for a decreasing temperature field and for hydrogen, temperature, and stress dependent diffusive transport of hydrogen to a generic hydride platelet at a crack tip. The development of the quasi-steady model is based on extensions of existing models for hydride precipitation kinetics for an isolated hydride platelet at a crack tip. An instability analysis model of hydride-crack growth was developed using existing concepts in a kinematic equation for crack propagation at a constant thermodynamic crack potential subject to brittle fracture conditions. At the time an instability is initiated, the crack propagation is no longer limited by hydride growth rate kinetics, but is then limited by stress rates. The model for slow hydride-crack growth will be further evaluated using existing available data. (authors)

  2. Speculations on the existence of hydride ions in proton conducting oxides

    DEFF Research Database (Denmark)

    Poulsen, F.W.

    2001-01-01

    The chemical and physical nature of the hydride ion is briefly treated. Several reactions of the hydride ion in oxides or oxygen atmosphere are given, A number of perovskites and inverse perovskites are listed. which contain the H- ion on the oxygen or B-anion sites in the archetype ABO(3) System...

  3. Pore-Confined Light Metal Hydrides for Energy Storage and Catalysis

    NARCIS (Netherlands)

    Bramwell, P.L.

    2017-01-01

    Light metal hydrides have enjoyed several decades of attention in the field of hydrogen storage, but their applications have recently begun to diversify more and more into the broader field of energy storage. For example, light metal hydrides have shown great promise as battery materials, in sensors

  4. Study on the Use of Hydride Fuel in High-Performance Light Water Reactor Concept

    Directory of Open Access Journals (Sweden)

    Haileyesus Tsige-Tamirat

    2015-01-01

    Full Text Available Hydride fuels have features which could make their use attractive in future advanced power reactors. The potential benefit of use of hydride fuel in HPLWR without introducing significant modification in the current core design concept of the high-performance light water reactor (HPLWR has been evaluated. Neutronics and thermal hydraulic analyses were performed for a single assembly model of HPLWR with oxide and hydride fuels. The hydride assembly shows higher moderation with softer neutron spectrum and slightly more uniform axial power distribution. It achieves a cycle length of 18 months with sufficient excess reactivity. At Beginning of Cycle the fuel temperature coefficient of the hydride assembly is higher whereas the moderator and void coefficients are lower. The thermal hydraulic results show that the achievable fuel temperature in the hydride assembly is well below the design limits. The potential benefits of the use of hydride fuel in the current design of the HPLWR with the achieved improvements in the core neutronics characteristics are not sufficient to justify the replacement of the oxide fuel. Therefore for a final evaluation of the use of hydride fuels in HPLWR concepts additional studies which include modification of subassembly and core layout designs are required.

  5. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, A.Z., E-mail: alezipo@yahoo.co [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Universidade Estadual Paulista- Unesp - Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Pedregulho, CEP 12516-410 Guaratingueta, SP (Brazil); Moura, F.; Onofre, T.B. [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Ramirez, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

    2010-10-22

    Research highlights: {yields} Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) {yields} This is a genuine technique to obtain nanoparticles at low temperature and short times {yields} Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 {sup o}C. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}) nanoparticles (BST) in the temperature range of 100-130 {sup o}C. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO{sub 3} as a minor impurity at lower syntheses temperatures. Typical FT-IR spectra for tetragonal (BST) nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH- groups, commonly found in materials obtained by HTMW process. FE/SEM revealed that lower syntheses temperatures led to a morphology that consisted of uniform grains while higher syntheses temperature consisted of big grains isolated and embedded in a matrix of small grains. TEM has shown BST nanoparticles with diameters between 40 and 80 nm. These results show that the HTMW synthesis route is rapid, cost effective, and could serve as an alternative to obtain BST nanoparticles.

  6. Barium as a potential indicator of phosphorus in agricultural runoff.

    Science.gov (United States)

    Ahlgren, Joakim; Djodjic, Faruk; Wallin, Mats

    2012-01-01

    In many catchments, anthropogenic input of contaminants, and in particular phosphorus (P), into surface water is a mixture of agricultural and sewage runoff. Knowledge about the relative contribution from each of these sources is vital for mitigation of major environmental problems such as eutrophication. In this study, we investigated whether the distribution of trace elements in surface waters can be used to trace the contamination source. Water from three groups of streams was investigated: streams influenced only by agricultural runoff, streams influenced mainly by sewage runoff, and reference streams. Samples were collected at different flow regimes and times of year and analyzed for 62 elements using ICP-MS. Our results show that there are significant differences between the anthropogenic sources affecting the streams in terms of total element composition and individual elements, indicating that the method has the potential to trace anthropogenic impact on surface waters. The elements that show significant differences between sources are strontium (p barium (p barium shows the greatest potential as a tracer for an individual source of anthropogenic input to surface waters. We observed a strong relationship between barium and total P in the investigated samples (R(2) = 0.78), which could potentially be used to apportion anthropogenic sources of P and thereby facilitate targeting of mitigation practices. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  7. Early colon cancer : findings on double contrast barium enema

    International Nuclear Information System (INIS)

    Kim, Seung Kwon; Lim, Jae Hoon; Lee, Soon Jin; Lim, Hyo Keun

    1998-01-01

    The purpose of this study is to describe the radiologic findings of early colon cancer on double-contrast barium enema. We retrospectively reviewed the double-contrast barium enemas of eight patients (M:F = 6:2; mean age : 67 yrs; range : 48-77 yrs) who were pathologically proven to be early colon cancer. The location, size and gross morphology of lesions was evaluated using double-contrast barium enema, while depth of invasion, degree of differentiation, precancerous lesions and lymph node metastasis were evaluated histopathologically. Early colon cancer was found in the rectum (n=4), sigmoid colon (n=3) and ascending colon (n=1). The size of mass ranged from 2.3 ∼ 8.3 (mean, 4.6) cm. And the polypoid type was most common (n=7); this was subdivided into sessile (Is, n=5), semipedunculated (Isp, n=1) and pedunculated type (Ip, n=1). Another mass was a sessile polypoid combined with a flat depressed lesion. In eight cases, four cancers were confined to the mucosa, while the remaining four had infiltrated the submucosa. Most cancers arose from villous and villotubular adenoma. All cases were well-differentiated adenocarcinoma and no metastasis to lymph nodes had occurred. In early colon cancer, lesions were mainly polypoid and large. Most arose from villous and villotubular adenoma. (author). 19 refs., 1 tab., 3 figs

  8. Aspiration of barium contrast medium in an elderly man with disordered swallowing

    OpenAIRE

    Bağcı Ceyhan, B.; Çelikel, T.; Koç, M.; Ahıskalı, R.; Biren, T.; Ataizi Çelikel, Ç.

    1995-01-01

    The aspiration of contrast medium during the investigation of gastrointestinal diseases is a well recognized hazard, particularly in patients with swallowing disorders. A case is reported in which accidental aspiration of contrast barium occurred owing to disordered swallowing in an elderly man. The infiltration on chest x-ray persisted 2 years after barium contrast aspiration. Inflammatory reaction and retractile, granular material observed in lung biopsy specimens suggested barium-induced p...

  9. Strontium-90 sorption from fresh waters in the process of barium manganite modification

    International Nuclear Information System (INIS)

    Ryzhen'kov, A.P.; Egorov, Yu.V.

    1995-01-01

    Strontium-90 extraction by barium manganite from fresh water (natural non-salty water in open ponds) may be increased adding to the solution the sulfate anion containing reagents that modify a sorbent and chemically bind a sorbate. Heterogeneous anion-exchanging reaction of barium manganite transformation into barium sulfate-manganese dioxide and simultaneous coprecipitation of strontium sulfate (microelement) occur as a result of it. 9 refs., 4 figs., 1 tab

  10. Simplified assessment of segmental gastrointestinal transit time with orally small amount of barium

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Weitang; Zhang, Zhiyong; Liu, Jinbo; Li, Zhen; Song, Junmin; Wu, Changcai [Department of Colorectal Surgery, The First Affiliated Hospital and Institute of Clinical Medicine, Zhengzhou University, 450052 Zhengzhou (China); Wang, Guixian, E-mail: guixianwang@hotmail.com [Department of Colorectal Surgery, The First Affiliated Hospital and Institute of Clinical Medicine, Zhengzhou University, 450052 Zhengzhou (China)

    2012-09-15

    Objective: To determine the effectiveness and advantage of small amount of barium in the measurement of gastrointestinal transmission function in comparison with radio-opaque pallets. Methods: Protocal 1: 8 healthy volunteers (male 6, female 2) with average age 40 ± 6.1 were subjected to the examination of radio-opaque pellets and small amount of barium with the interval of 1 week. Protocol 2: 30 healthy volunteers in group 1 (male 8, female 22) with average age 42.5 ± 8.1 and 50 patients with chronic functional constipation in group 2 (male 11, female 39) with average age 45.7 ± 7.8 were subjected to the small amount of barium examination. The small amount of barium was made by 30 g barium dissolved in 200 ml breakfast. After taking breakfast which contains barium, objectives were followed with abdominal X-ray at 4, 8, 12, 24, 48, 72, 96 h until the barium was evacuated totally. Results: Small amount of barium presented actual chyme or stool transit. The transit time of radio-opaque pallets through the whole gastrointestinal tract was significantly shorter than that of barium (37 ± 8 h vs. 47 ± 10 h, P < 0.05) in healthy people. The transit times of barium in constipation patients were markedly prolonged in colon (61.1 ± 22 vs. 37.3 ± 11, P < 0.01) and rectum (10.8 ± 3.7 vs. 2.3 ± 0.8 h, P < 0.01) compared with unconstipated volunteers. Transit times in individual gastrointestinal segments were also recorded by using small amount of barium, which allowed identifying the subtypes of constipation. Conclusion: The small amount barium examination is a convenient and low cost method to provide the most useful and reliable information on the transmission function of different gastrointestinal segments and able to classify the subtypes of slow transit constipation.

  11. Simplified assessment of segmental gastrointestinal transit time with orally small amount of barium

    International Nuclear Information System (INIS)

    Yuan, Weitang; Zhang, Zhiyong; Liu, Jinbo; Li, Zhen; Song, Junmin; Wu, Changcai; Wang, Guixian

    2012-01-01

    Objective: To determine the effectiveness and advantage of small amount of barium in the measurement of gastrointestinal transmission function in comparison with radio-opaque pallets. Methods: Protocal 1: 8 healthy volunteers (male 6, female 2) with average age 40 ± 6.1 were subjected to the examination of radio-opaque pellets and small amount of barium with the interval of 1 week. Protocol 2: 30 healthy volunteers in group 1 (male 8, female 22) with average age 42.5 ± 8.1 and 50 patients with chronic functional constipation in group 2 (male 11, female 39) with average age 45.7 ± 7.8 were subjected to the small amount of barium examination. The small amount of barium was made by 30 g barium dissolved in 200 ml breakfast. After taking breakfast which contains barium, objectives were followed with abdominal X-ray at 4, 8, 12, 24, 48, 72, 96 h until the barium was evacuated totally. Results: Small amount of barium presented actual chyme or stool transit. The transit time of radio-opaque pallets through the whole gastrointestinal tract was significantly shorter than that of barium (37 ± 8 h vs. 47 ± 10 h, P < 0.05) in healthy people. The transit times of barium in constipation patients were markedly prolonged in colon (61.1 ± 22 vs. 37.3 ± 11, P < 0.01) and rectum (10.8 ± 3.7 vs. 2.3 ± 0.8 h, P < 0.01) compared with unconstipated volunteers. Transit times in individual gastrointestinal segments were also recorded by using small amount of barium, which allowed identifying the subtypes of constipation. Conclusion: The small amount barium examination is a convenient and low cost method to provide the most useful and reliable information on the transmission function of different gastrointestinal segments and able to classify the subtypes of slow transit constipation

  12. Thermodynamic changes in mechanochemically synthesised magnesium hydride nanoparticles

    International Nuclear Information System (INIS)

    Sheppard, Drew A.; Paskevicius, Mark; Buckley, Craig E.

    2009-01-01

    Full text: Hydrogen storage is a critical issue that must be overcome on the path towards realizing a hydrogel economy. Solid state storage of hydrogen in magnesium hydride (MgH 2 ) is an attractive solution due to its high hydrogen capacity and the relatively low cost and abundance of magnesium. However, the high thermal stability of MgH 2 makes it difficult to extract the hydrogen at near ambient conditions Recent theoretical work [1 - 3] suggests that reducing the particle size below 1 0 n m will reduce the enthalpy of MgH 2 resulting in a lower desorption temperature, with the effect becoming pronouncec below 3n m. We have used a mechanochemical ball milling method [4] to synthesize MgH; nanoparticles separated by a LiCI matrix. The change in microstructure of the synthesized MgH 2 as a function of the volume of LiCI used during the mechanochemical process was examined by Transmission Electron Microscopy, neutron diffraction and synchrotron x-ray diffraction and compared to the corresponding thermodynamic data obtained from hydrogen desorption measurements. The results show a decrease in enthalpy, in accord with theoretical studies, but that the decrease in desorption temperature is less than that expected due to a counteracting decrease in the entropy of MgH 2 [5]. This has consequences for current experimental research directions into nanosized hydride particles and suggests that future theoretical work must also take into account changes in the entropy in determining the thermodynamic changes in hydride nanoparticles.

  13. Delayed hydride cracking velocity in CANDU and RBMK pressure tubes

    International Nuclear Information System (INIS)

    Markelov, V.A.; Nikulina, A.V.; Zheltkovskaya, T.N.; Tsvelev, V.V.

    2001-01-01

    Using a unified technique applied world-wide comparative tests were implemented to determine delayed hydride cracking (DHC) velocities in CANDU Zr-2.5Nb pressure tubes, RBMK standard and TMT-2 pressure tubes of Zr-2.5 Nb alloy and in RBMK E635 (Zr-1.2Sn-1Nb-0.35Fe) pressure tubes. The tests were carried on at 250 degree C using standard compact tension specimens 17 mm wide hydrogenated to 1 x 10 -4 and having an axial crack. The initial stress intensity factor (K 1 ) was specified as 15-20 MPa·√m. During testing the crack increment was controlled by the potential drop method while the true crack length that was used to calculate its evolution velocity was found after the specimen broke apart. The results of the tests evidence that the highest DHC velocity is inherent in the CANDU pressure tubes. The DHC velocity in the RBMK pressure tubes is lower by an order and even more. This difference in the DHC velocities proceeds from the dissimilar strengths of the CANDU and RBMK tubes and the specific features of their structures. The DHC velocity in the RBMK tubes also depends on their strength. The highest DHC resistance is demonstrated by the RBMK pressure tubes subjected to the standard treatment. For the initiate a hydride crack in them a much longer incubation period and a higher value of the initial stress intensity factor are needed. The DHC related problem is most urgent for the CANDU pressure tubes. To increase their resistance to hydride effected cracking their texture has to approach that of the RBMK pressure tubes. In doing so all the other operation properties inherent in the CANDU pressure tubes have to be retained at the previously achieved level

  14. ALUMINUM HYDRIDE: A REVERSIBLE MATERIAL FOR HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Zidan, R; Christopher Fewox, C; Brenda Garcia-Diaz, B; Joshua Gray, J

    2009-01-09

    Hydrogen storage is one of the challenges to be overcome for implementing the ever sought hydrogen economy. Here we report a novel cycle to reversibly form high density hydrogen storage materials such as aluminium hydride. Aluminium hydride (AlH{sub 3}, alane) has a hydrogen storage capacity of 10.1 wt% H{sub 2}, 149 kg H{sub 2}/m{sup 3} volumetric density and can be discharged at low temperatures (< 100 C). However, alane has been precluded from use in hydrogen storage systems because of the lack of practical regeneration methods. The direct hydrogenation of aluminium to form AlH{sub 3} requires over 10{sup 5} bars of hydrogen pressure at room temperature and there are no cost effective synthetic means. Here we show an unprecedented reversible cycle to form alane electrochemically, using alkali metal alanates (e.g. NaAlH{sub 4}, LiAlH{sub 4}) in aprotic solvents. To complete the cycle, the starting alanates can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride being the other compound formed in the electrochemical cell. The process of forming NaAlH{sub 4} from NaH and Al is well established in both solid state and solution reactions. The use of adducting Lewis bases is an essential part of this cycle, in the isolation of alane from the mixtures of the electrochemical cell. Alane is isolated as the triethylamine (TEA) adduct and converted to pure, unsolvated alane by heating under vacuum.

  15. ALUMINUM HYDRIDE: A REVERSIBLE MATERIAL FOR HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Fewox, C; Ragaiy Zidan, R; Brenda Garcia-Diaz, B

    2008-12-31

    Hydrogen storage is one of the greatest challenges for implementing the ever sought hydrogen economy. Here we report a novel cycle to reversibly form high density hydrogen storage materials such as aluminium hydride. Aluminium hydride (AlH{sub 3}, alane) has a hydrogen storage capacity of 10.1 wt% H{sub 2}, 149 kg H{sub 2}/m{sup 3} volumetric density and can be discharged at low temperatures (< 100 C). However, alane has been precluded from use in hydrogen storage systems because of the lack of practical regeneration methods; the direct hydrogenation of aluminium to form AlH{sub 3} requires over 10{sup 5} bars of hydrogen pressure at room temperature and there are no cost effective synthetic means. Here we show an unprecedented reversible cycle to form alane electrochemically, using alkali alanates (e.g. NaAlH{sub 4}, LiAlH{sub 4}) in aprotic solvents. To complete the cycle, the starting alanates can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride being the other compound formed in the electrochemical cell. The process of forming NaAlH{sub 4} from NaH and Al is well established in both solid state and solution reactions. The use of adducting Lewis bases is an essential part of this cycle, in the isolation of alane from the mixtures of the electrochemical cell. Alane is isolated as the triethylamine (TEA) adduct and converted to pure, unsolvated alane by heating under vacuum.

  16. Mathematical modeling of the nickel/metal hydride battery system

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, Blaine Kermit [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering

    1995-09-01

    A group of compounds referred to as metal hydrides, when used as electrode materials, is a less toxic alternative to the cadmium hydroxide electrode found in nickel/cadmium secondary battery systems. For this and other reasons, the nickel/metal hydride battery system is becoming a popular rechargeable battery for electric vehicle and consumer electronics applications. A model of this battery system is presented. Specifically the metal hydride material, LaNi{sub 5}H{sub 6}, is chosen for investigation due to the wealth of information available in the literature on this compound. The model results are compared to experiments found in the literature. Fundamental analyses as well as engineering optimizations are performed from the results of the battery model. In order to examine diffusion limitations in the nickel oxide electrode, a ``pseudo 2-D model`` is developed. This model allows for the theoretical examination of the effects of a diffusion coefficient that is a function of the state of charge of the active material. It is found using present data from the literature that diffusion in the solid phase is usually not an important limitation in the nickel oxide electrode. This finding is contrary to the conclusions reached by other authors. Although diffusion in the nickel oxide active material is treated rigorously with the pseudo 2-D model, a general methodology is presented for determining the best constant diffusion coefficient to use in a standard one-dimensional battery model. The diffusion coefficients determined by this method are shown to be able to partially capture the behavior that results from a diffusion coefficient that varies with the state of charge of the active material.

  17. Laboratory Rotational Spectroscopy of Astrophysical Interesting Diatomic Hydrides

    Science.gov (United States)

    Halfen, DeWayne; Ziurys, L.

    2008-05-01

    Diatomic hydride are among the most common molecular species in the interstellar medium (ISM). The low molecular mass and thus moments of inertia cause their rotational spectra to lie entirely in the submillimeter and far-infrared regions. Hence, the future airborne and space-borne platforms, such as SOFIA and Herschel, are primed to explore these prevalent molecules. However, in order to detect these species in the ISM, their rotational spectra must first be measured in the laboratory. Using submillimeter direct absorption methods in the Ziurys laboratory, we have recorded the spectra of several diatomic hydrides of astrophysical interest. We have measured the pure rotational spectrum of MnH (X7Σ+: N = 0 - 1) and MnD (N = 2 - 3), as well as the deuterium and carbon-13 isotopologues of CH, CD (X2Πr: N = 1 - 1 and 1 - 2) and 13CH (N = 1 - 1). Manganese hydride and deuteride were created in a DC discharge of H2 or D2 and manganese vapor, generated in a Broida-type oven. CD and 13CH were produced in an AC discharge of argon and CD4 or 13CH4. For MnH, the five strongest manganese hyperfine transitions were recorded in its N = 0 - 1 transition, each of which are additionally split by hydrogen hyperfine interactions. CD and 13CH also have multiple hyperfine components due to the D, 13C, and/or H atoms. The direct measurement of these fundamental transitions will allow for unambiguous astronomical detections. The results of these studies will be presented.

  18. Another Look at the Mechanisms of Hydride Transfer Enzymes with Quantum and Classical Transition Path Sampling.

    Science.gov (United States)

    Dzierlenga, Michael W; Antoniou, Dimitri; Schwartz, Steven D

    2015-04-02

    The mechanisms involved in enzymatic hydride transfer have been studied for years, but questions remain due, in part, to the difficulty of probing the effects of protein motion and hydrogen tunneling. In this study, we use transition path sampling (TPS) with normal mode centroid molecular dynamics (CMD) to calculate the barrier to hydride transfer in yeast alcohol dehydrogenase (YADH) and human heart lactate dehydrogenase (LDH). Calculation of the work applied to the hydride allowed for observation of the change in barrier height upon inclusion of quantum dynamics. Similar calculations were performed using deuterium as the transferring particle in order to approximate kinetic isotope effects (KIEs). The change in barrier height in YADH is indicative of a zero-point energy (ZPE) contribution and is evidence that catalysis occurs via a protein compression that mediates a near-barrierless hydride transfer. Calculation of the KIE using the difference in barrier height between the hydride and deuteride agreed well with experimental results.

  19. Complex rare-earth aluminum hydrides: mechanochemical preparation, crystal structure and potential for hydrogen storage.

    Science.gov (United States)

    Weidenthaler, Claudia; Pommerin, André; Felderhoff, Michael; Sun, Wenhao; Wolverton, Christopher; Bogdanović, Borislav; Schüth, Ferdi

    2009-11-25

    A novel type of complex rare-earth aluminum hydride was prepared by mechanochemical preparation. The crystal structure of the REAlH(6) (with RE = La, Ce, Pr, Nd) compounds was calculated by DFT methods and confirmed by preliminary structure refinements. The trigonal crystal structure consists of isolated [AlH(6)](3-) octahedra bridged via [12] coordinated RE cations. The investigation of the rare-earth aluminum hydrides during thermolysis shows a decrease of thermal stability with increasing atomic number of the RE element. Rare-earth hydrides (REH(x)) are formed as primary dehydrogenation products; the final products are RE-aluminum alloys. The calculated decomposition enthalpies of the rare-earth aluminum hydrides are at the lower end for reversible hydrogenation under moderate conditions. Even though these materials may require somewhat higher pressures and/or lower temperatures for rehydrogenation, they are interesting examples of low-temperature metal hydrides for which reversibility might be reached.

  20. Single-Site Tetracoordinated Aluminum Hydride Supported on Mesoporous Silica. From Dream to Reality!

    KAUST Repository

    Werghi, Baraa

    2016-09-26

    The reaction of mesoporous silica (SBA15) dehydroxylated at 700 °C with diisobutylaluminum hydride, i-Bu2AlH, gives after thermal treatment a single-site tetrahedral aluminum hydride with high selectivity. The starting aluminum isobutyl and the final aluminum hydride have been fully characterized by FT-IR, advanced SS NMR spectroscopy (1H, 13C, multiple quanta (MQ) 2D 1H-1H, and 27Al), and elemental analysis, while DFT calculations provide a rationalization of the occurring reactivity. Trimeric i-Bu2AlH reacts selectively with surface silanols without affecting the siloxane bridges. Its analogous hydride catalyzes ethylene polymerization. Indeed, catalytic tests show that this single aluminum hydride site is active in the production of a high-density polyethylene (HDPE). © 2016 American Chemical Society.

  1. Kinetics and mechanism of the hydridation of uranium and rare-earth metals

    International Nuclear Information System (INIS)

    Bloch, J.

    1989-07-01

    The purpose of this work was to study the rate and the mechanism of the hydridation reaction of uranium and the lanthanide metals. Surface sensitive analysis was used to study the reaction of the metal surface with residual gases of the high vacuum atmosphere. The initial stages of the uranium-hydrogen reaction, taking place on a polished metal surface, were investigated utilizing a hot-stage microscope equipped with TV camera and a video-recorder. The characteristics of formation and advance mechanism of hydride phase in bulk uranium and lanthanide metals were studied utilizing metallographic examination of partially hydrided thin foil samples at different stages of the reaction. The interface velocity of the hydride in uranium was measured as a function of pressure and temprature in a constant volume system. A probabilistic kinetic model for a gas-solid interaction, controlled by a phase transformation step, was developed and applied to the hydridation of uranium and gadolinium

  2. Analytical and numerical models of uranium ignition assisted by hydride formation

    International Nuclear Information System (INIS)

    Totemeier, T.C.; Hayes, S.L.

    1996-01-01

    Analytical and numerical models of uranium ignition assisted by the oxidation of uranium hydride are described. The models were developed to demonstrate that ignition of large uranium ingots could not occur as a result of possible hydride formation during storage. The thermodynamics-based analytical model predicted an overall 17 C temperature rise of the ingot due to hydride oxidation upon opening of the storage can in air. The numerical model predicted locally higher temperature increases at the surface; the transient temperature increase quickly dissipated. The numerical model was further used to determine conditions for which hydride oxidation does lead to ignition of uranium metal. Room temperature ignition only occurs for high hydride fractions in the nominally oxide reaction product and high specific surface areas of the uranium metal

  3. Effects of powdered versus liquid barium on the viscosity of fluids used in modified swallow studies

    Energy Technology Data Exchange (ETDEWEB)

    Baron, J.; Alexander, T. [Univ. of Alberta, Dept. of Radiology, Edmonton, Alberta (Canada)

    2003-06-01

    To determine if the viscosity of thickened juice mixtures used in modified barium swallow studies significantly changes with the addition of powdered barium. We also describe a test formulation created using liquid barium, which has a negligible effect on juice viscosity. The viscosities of water and standardized honey- and nectar-consistency juices mixed with different amounts of powdered barium were measured by timing the laminar flow of a given initial hydrostatic head of fluid under gravity though an orifice of fixed diameter. Standardized juices were then mixed with a liquid formulation of barium and with measured quantities of water to produce viscosities that more closely equated with those of the standardized juices. With the addition of powdered barium, viscosity increased in all fluids, most markedly with the nectar-consistency juice. Liquid barium formulations maintained the viscosities of the original thickened juices. Rendering juices radio-opaque with barium powder results in dramatic increases in the viscosity of the resulting mixture and compromises diagnostic accuracy. Liquid barium preparations have the advantage that they can be rapidly and accurately dispensed by syringe, and their use does not significantly increase the viscosity of the preparation. (author)

  4. Results of a cooperative study for the evaluation of the barium meal Falibaryt HD

    International Nuclear Information System (INIS)

    Reisinger, W.; Liess, G.; Beckmann, D.; Block, H.G.; Dietze, R.; Grosche, N.; Hall, E.; Lasch, G.; Knoth, H.J.; Kroeger, W.

    1986-01-01

    The diagnostic capabilities of radiologic investigations of the stomach in double contrast can be significantly improved with high-density low-viscosity barium meals. In the GDR the barium meal Falibaryt HD with a barium sulfate content of 215 g per 100 ml suspension has been developed. In nearly 1,000 radiologic investigations of the stomach (81% in relaxation with spasmolytics, 66% without hypotony) all fine structures were well imaged and the preparation therefore is comparable with the best barium meals presently on the market. (author)

  5. Barium titanate coated with magnesium titanate via fused salt method and its dielectric property

    International Nuclear Information System (INIS)

    Chen Renzheng; Cui Aili; Wang Xiaohui; Li Longtu

    2003-01-01

    Barium titanate fine particles were coated homogeneously with magnesium titanate via the fused salt method. The thickness of the magnesium titanate film is 20 nm, as verified by TEM and XRD. The mechanism of the coating is that: when magnesium chloride is liquated in 800 deg. C, magnesium will replace barium in barium titanate, and form magnesium titanate film on the surface of barium titanate particles. Ceramics sintered from the coated particles show improved high frequency ability. The dielectric constant is about 130 at the frequency from 1 to 800 MHz

  6. High Resolution Computed Tomography Appearences of late sequelae of Barium Aspiration in an asymptomatic young child

    International Nuclear Information System (INIS)

    Venkatraman, Bhat; Rahman, Hatim A.; Abdul-Wahab, Atiqa

    2005-01-01

    Barium aspiration is a well-known complication of upper gastro-intestinal studies. Consequences of aspiration are generally insignificant and leave no permanent changes in the lung parenchyma. However, large quantities of high density barium, if aspirated, lead to silent interstitial changes and fibrosis. High-resolution computed tomography HRCT appearances of lung changes have been demonstrated in adults; few such reports are available in the pediatric literature. We report a case of a child who aspirated barium 3 months before this presentation. The HRCT appearances of barium aspiration are presented with a review of the literature. (author)

  7. Hydrothermal synthesis of barium germanate microrods and photocatalytic degradation performance for methyl blue

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei@ahut.edu.cn [Key Lab of Materials Science and Processing of Anhui Province, School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan, Anhui 243002 (China); Wang, S.; Xie, Y.K.; Yu, H.Y. [Key Lab of Materials Science and Processing of Anhui Province, School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan, Anhui 243002 (China); Guo, Y.H. [Department of Materials Science, Fudan University, Shanghai 200433 (China)

    2014-02-25

    Highlights: • Barium germanate microrods have been synthesized by a simple hydrothermal process. • The size of the barium germanate microrods can be controlled by growth conditions. • Barium germanate microrods exhibit good photocatalytic activities for methyl blue. -- Abstract: Barium germanate microrods were prepared by a facile hydrothermal process without any surfactants. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and photoluminescence spectra were used to characterize the structure, morphology, size and optical properties of the barium germanate microrods. XRD and SEM observations show that the microrods with hexagonal BaGe{sub 4}O{sub 9} phase have the diameter of 500 nm to 1.5 μm. The size of the barium germanate microrods can be tuned by controlling the hydrothermal temperature, reaction time and surfactants. The influence factors including the irradiation time, content of the barium germanate microrods and MB concentration on the photocatalytic degradation of methylene blue (MB) have been analyzed. The barium germanate microrods show a MB degradation ratio of 83.49% after the irradiation time for 30 min using 1.25 mg/ml barium germanate microrods in 10 mgL{sup −1} MB solution.

  8. Modification of the hydriding of uranium using ion implantation

    International Nuclear Information System (INIS)

    Musket, R.G.; Robinson-Weis, G.; Patterson, R.G.

    1983-01-01

    The hydriding of depleted uranium at 76 Torr hydrogen and 130 0 C has been significantly reduced by implantation of oxygen ions. The high-dose implanted specimens had incubation times for the initiation of the reaction after exposure to hydrogen that exceeded those of the nonimplanted specimens by more than a factor of eight. Furthermore, the nonimplanted specimens consumed enough hydrogen to cause macroscopic flaking of essentially the entire surface in times much less than the incubation time for the high-dose implanted specimens. In contrast, the ion-implanted specimens reacted only at isolated spots with the major fraction of the surface area unaffected by the hydrogen exposure

  9. Equilibrium composition for the reaction of plutonium hydride with air

    International Nuclear Information System (INIS)

    Zou Lexi; Sun Ying; Xue Weidong; Zhu Zhenghe; Wang Rong; Luo Deli

    2002-01-01

    There are six independent constituents with 4 chemical elements, i.e. PuH 2.7 (s), PuN(s), Pu 2 O 3 (s), N 2 , O 2 and H 2 , therefore, the system described involves of 2 independent reactions, both ΔG 0 <<0. The calculated equilibrium compositions are in agreement with those of the experimental, which indicates that the chemical equilibrium is nearly completely approached. Therefore, it is believed that the reaction rate of plutonium hydride with air is extremely rapid. The author has briefly discussed the simultaneous reactions and its thermodynamic coupling effect

  10. Parametrization of a reactive force field for aluminum hydride

    OpenAIRE

    Ojwang, J. G. O.; van Santen, Rutger A.; Kramer, Gert Jan; van Duin, Adri C. T.; Goddard, William A., III

    2009-01-01

    A reactive force field, REAXFF, for aluminum hydride has been developed based on density functional theory (DFT) derived data. REAXFF_(AlH_3) is used to study the dynamics governing hydrogen desorption in AlH_3. During the abstraction process of surface molecular hydrogen charge transfer is found to be well described by REAXFF_(AlH_3). Results on heat of desorption versus cluster size show that there is a strong dependence of the heat of desorption on the particle size, which implies that nan...

  11. Electrochemical process and production of novel complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy

    2013-06-25

    A process of using an electrochemical cell to generate aluminum hydride (AlH.sub.3) is provided. The electrolytic cell uses a polar solvent to solubilize NaAlH.sub.4. The resulting electrochemical process results in the formation of AlH.sub.3. The AlH.sub.3 can be recovered and used as a source of hydrogen for the automotive industry. The resulting spent aluminum can be regenerated into NaAlH.sub.4 as part of a closed loop process of AlH.sub.3 generation.

  12. Hydrogen isotope exchange in a metal hydride tube

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, David B. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2014-09-01

    This report describes a model of the displacement of one hydrogen isotope within a metal hydride tube by a different isotope in the gas phase that is blown through the tube. The model incorporates only the most basic parameters to make a clear connection to the theory of open-tube gas chromatography, and to provide a simple description of how the behavior of the system scales with controllable parameters such as gas velocity and tube radius. A single tube can be seen as a building block for more complex architectures that provide higher molar flow rates or other advanced design goals.

  13. Research in Nickel/Metal Hydride Batteries 2016

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-10-01

    Full Text Available Nineteen papers focusing on recent research investigations in the field of nickel/metal hydride (Ni/MH batteries have been selected for this Special Issue of Batteries. These papers summarize the joint efforts in Ni/MH battery research from BASF, Wayne State University, the National Institute of Standards and Technology, Michigan State University, and FDK during 2015–2016 through reviews of basic operational concepts, previous academic publications, issued US Patent and filed Japan Patent Applications, descriptions of current research results in advanced components and cell constructions, and projections of future works.

  14. Radiation losses in microwave K{sub u} region by conducting pyrrole/barium titanate and barium hexaferrite based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Talwinder [Department of Physics, Lovely Professional University, Phagwara 144411 (India); Kumar, Sachin [Department of Chemistry, Guru Nanak Dev University, Amritsar 143005 (India); Narang, S.B. [Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005 (India); Srivastava, A.K., E-mail: srivastava_phy@yahoo.co.in [Department of Physics, Lovely Professional University, Phagwara 144411 (India)

    2016-12-15

    Nanocomposites of substituted barium hexaferrite and barium titanate embedded in a polymer were synthesized via emulsion polymerization. The study was performed by using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, electron spin resonance spectroscopy, a vibrating sample magnetometer and a vector network analyzer. It is found that maximum radiation loss occur at 16.09 GHz (−14.23 dB) frequency owing to the combined effect of conducting polymer, suitable dielectric and magnetic material. This suggests that prepared material is suitable for radiation losses. Micro structural study reveals the presence of all the phases of the compounds comprises composite. Benzene ring absorption band (at 1183 cm{sup −1}) in FT-IR spectra illustrates the presence of polymer. Surface morphology reveals the presence of array of particles encapsulated by the polymer. - Highlights: • Composites having polymer, barium titanate and hexaferrite have been successfully prepared. • Effective radiation absorption and losses have been achieved. • Magnetic properties have made an impact on shielding effectiveness.

  15. Adsorption behaviors of surface active reagents on barium ferrite magnetic fine particles; Barium ferrite jisei biryushi eno hymen shorizai kyuchaku

    Energy Technology Data Exchange (ETDEWEB)

    Kudo, M.; Otani, T.; Masuko, T. [Yamagata University, Yamagata (Japan). Faculty of Engineering

    1998-06-10

    The adsorption mode of lecithin (dioleoylphosphatidylcholine) or [3-(methacryloyloxy)propyl] trimethoxysilane (MPS) onto barium ferrite magnetic particles has been investigated by measurements of changes in solution concentration of the surfactant. Both adsortion isotherms of the surface active reagents on barium ferrite particles indicated to be of the Langmuir type. The occupied areas per one molecule on the surface of barium ferrite particles were estimated to be about 70 angstrom{sup 2}/molecule for lecithin and 22 angstrom{sup 2}/molecule for MPS at their saturated adsorption. In X-ray photoelectron spectroscopy (XPS) measurements for the adsorbed lecithin layer, the peak position in the binding energy distribution for the P (2p) photoelectron was observed to shift into slightly higher values with increasing amount of adsorbed lecithin. This implies that dipole-dipole interactions among the lecithin molecules become stronger because of increased high molecular packing in the adsorption layers. However, the peak position for the Si (2p) photoelectron remains almost unchanged due to slight interaction among the adsorbing functional groups onto the particles. 16 refs., 16 figs., 3 tabs.

  16. Method of generating hydrogen-storing hydride complexes

    Science.gov (United States)

    None, None

    2013-05-14

    A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

  17. Gas desorption properties of ammonia borane and metal hydride composites

    International Nuclear Information System (INIS)

    Matin, M.R.

    2009-01-01

    'Full text': Ammonia borane (NH 3 BH 3 ) has been of great interest owing to its ideal combination of low molecular weight and high H 2 storage capacity of 19.6 mass %, which exceeds the current capacity of gasoline. DOE's year 2015 targets involve gravimetric as well as volumetric energy densities. In this work, we have investigated thermal decomposition of ammonia borane and calcium hydride composites at different molar ratio. The samples were prepared by planetary ball milling under hydrogen gas atmosphere pressure of 1Mpa at room temperature for 2, and 10 hours. The gas desorption properties were examined by thermal desorption mass spectroscopy (TDMS). The identification of phases was carried out by X-ray diffraction. The results obtain were shown in fig (a),(b),and (c). Hydrogen desorption properties were observed at all molar ratios, but the desorption temperature is significantly lower at around 70 o C at molar ratio 1:1 as shown in fig (c), and unwanted gas (ammonia) emissions were remarkably suppressed by mixing with the calcium hydride. (author)

  18. Electronic structure of the palladium hydride studied by compton scattering

    CERN Document Server

    Mizusaki, S; Yamaguchi, M; Hiraoka, N; Itou, M; Sakurai, Y

    2003-01-01

    The hydrogen-induced changes in the electronic structure of Pd have been investigated by Compton scattering experiments associated with theoretical calculations. Compton profiles (CPs) of single crystal of Pd and beta phase hydride PdH sub x (x=0.62-0.74) have been measured along the [100], [110] and [111] directions with a momentum resolution of 0.14-0.17 atomic units using 115 keV x-rays. The theoretical Compton profiles have been calculated from the wavefunctions obtained utilizing the full potential linearized augmented plane wave method within the local density approximation for Pd and stoichiometric PdH. The experimental and the theoretical results agreed well with respect to the difference in the CPs between PdH sub x and Pd, and the anisotropy in the CPs of Pd or PdH sub x. This study provides lines of evidence that upon hydride formation the lowest valance band of Pd is largely modified due to hybridization with H 1s-orbitals and the Fermi energy is raised into the sp-band. (author)

  19. Electronically Unsaturated Three-Coordinate Aluminum Hydride and Organoaluminum Cations.

    Science.gov (United States)

    Prashanth, Billa; Bhandari, Mamta; Ravi, Satyam; Shamasundar, K R; Singh, Sanjay

    2018-02-16

    New three-coordinate and electronically unsaturated aluminum hydride [LAlH] + [HB(C 6 F 5 ) 3 ] - (LH=[{(2,6-iPr 2 C 6 H 3 N)P(Ph 2 )} 2 N]H) and aluminum methyl [LAlMe] + [MeB(C 6 F 5 ) 3 ] - cations have been prepared. The quantitative estimation of Lewis acidity by Gutmann-Beckett method revealed [LAlH] + [HB(C 6 F 5 ) 3 ] - to be better Lewis acid than B(C 6 F 5 ) 3 and AlCl 3 making these compounds ideal catalysts for Lewis acid-mediated reactions. To highlight that the work is of fundamental importance, catalytic hydroboration of aliphatic and aromatic aldehydes and ketones have been demonstrated. Important steps of the catalytic cycle have been probed by using multinuclear NMR measurements, including successful characterization of the proposed aluminum benzyloxide cationic intermediate, [LAl-O-CH 2 Ph] + [HB(C 6 F 5 ) 3 ] - . The proposed catalytic cycle has been found to be consistent with experimental observations and computational studies clearly indicating the migration of hydride from cationic aluminum center to the carbonyl carbon is the rate-limiting step of the catalytic cycle. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. X-ray photochemistry of carbon hydride molecular ions.

    Science.gov (United States)

    Puglisi, Alessandra; Miteva, Tsveta; Kennedy, Eugene T; Mosnier, Jean-Paul; Bizau, Jean-Marc; Cubaynes, Denis; Sisourat, Nicolas; Carniato, Stéphane

    2018-02-07

    Hydride molecular ions are key ingredients of the interstellar chemistry since they are precursors of more complex molecules. In regions located near a soft X-ray source these ions may resonantly absorb an X-ray photon which triggers a complex chain of reactions. In this work, we simulate ab initio the X-ray absorption spectrum, Auger decay processes and the subsequent fragmentation dynamics of two hydride molecular ions, namely CH 2 + and CH 3 + . We show that these ions feature strong X-ray absorption resonances which relax through Auger decay within 7 fs. The doubly-charged ions thus formed mostly dissociate into smaller ionic carbon fragments: in the case of CH 2 + , the dominant products are either C + /H + /H or CH + /H + . For CH 3 + , the system breaks primary into CH 2 + and H + , which provides a new route to form CH 2 + near a X-ray source. Furthermore, our simulations provide the branching ratios of the final products formed after the X-ray absorption as well as their kinetic and internal energy distributions. Such data can be used in the chemistry models of the interstellar medium.

  1. ACCEPTABILITY ENVELOPE FOR METAL HYDRIDE-BASED HYDROGEN STORAGE SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, B.; Corgnale, C.; Tamburello, D.; Garrison, S.; Anton, D.

    2011-07-18

    The design and evaluation of media based hydrogen storage systems requires the use of detailed numerical models and experimental studies, with significant amount of time and monetary investment. Thus a scoping tool, referred to as the Acceptability Envelope, was developed to screen preliminary candidate media and storage vessel designs, identifying the range of chemical, physical and geometrical parameters for the coupled media and storage vessel system that allow it to meet performance targets. The model which underpins the analysis allows simplifying the storage system, thus resulting in one input-one output scheme, by grouping of selected quantities. Two cases have been analyzed and results are presented here. In the first application the DOE technical targets (Year 2010, Year 2015 and Ultimate) are used to determine the range of parameters required for the metal hydride media and storage vessel. In the second case the most promising metal hydrides available are compared, highlighting the potential of storage systems, utilizing them, to achieve 40% of the 2010 DOE technical target. Results show that systems based on Li-Mg media have the best potential to attain these performance targets.

  2. A review of the health impacts of barium from natural and anthropogenic exposure.

    Science.gov (United States)

    Kravchenko, Julia; Darrah, Thomas H; Miller, Richard K; Lyerly, H Kim; Vengosh, Avner

    2014-08-01

    There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food.

  3. The diagnosis of gastro-esophageal reflux disease cannot be made with barium esophagograms.

    Science.gov (United States)

    Saleh, C M G; Smout, A J P M; Bredenoord, A J

    2015-02-01

    For over 50 years, barium studies have been used to diagnose gastro-esophageal reflux disease (GERD), but the value of this test is controversial. Our study aimed to determine if barium esophagograms can be used to diagnose GERD. Barium esophagograms and pH-impedance measurement were performed in 20 subjects with reflux symptoms. pH-impedance measurements were used as gold standard for the diagnosis of GERD. Gastro-esophageal reflux measured with the barium study was defined as a positive outcome. 50% of patients presented gastro-esophageal reflux on the barium esophagogram. No significant differences were observed in acid exposure time between subjects with (median: 7.4%; interquartile range, IQR: 8.4%) or without reflux at barium esophagography (median: 5.95%; IQR: 13.05%; p > 0.05). Nor did we find differences in median proximal extent of reflux measured with impedance monitoring between patients with a positive (median: 6.7%; IQR: 1.95%) and negative barium study (median: 7.1%; IQR: 0.68%; p > 0.05). Patients with reflux on barium esophagogram did not have a positive symptom association probability more often than those who did not have reflux at barium esophagography. Lastly, there were no differences in numbers of acid, weakly acidic or total reflux episodes between those with positive or negative barium esophagogram (p > 0.05). No correlations were found between the maximum proximal extent of gastro-esophageal reflux during esophagography and pH-impedance parameters. Presence or absence of gastro-esophageal reflux during barium esophagography does not correlate with incidence or extent of reflux observed during 24-h pH-impedance monitoring and is not of value for the diagnosis of GERD. © 2014 John Wiley & Sons Ltd.

  4. Multi-scale characterization of nanostructured sodium aluminum hydride

    Science.gov (United States)

    NaraseGowda, Shathabish

    Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are expected to improve in performance and reversibility. This area of research has garnered immense interest lately and there is active research being pursued to address various aspects of nanostructured complex hydrides. The research effort documented here is focused on a detailed investigation of the effects of nano-confinement on aspects such as the long range atomic hydrogen diffusivities, localized hydrogen dynamics, microstructure, and dehydrogenation mechanism of sodium alanate. A wide variety of microporous and mesoporous materials (metal organic frameworks, porous silica and alumina) were investigated as scaffolds and the synthesis routes to achieve maximum pore-loading are discussed. Wet solution infiltration technique was adopted using tetrahydrofuran as the medium and the precursor concentrations were found to have a major role in achieving maximum pore loading. These concentrations were optimized for each scaffold with varying pore sizes and confinement was quantitatively characterized by measuring the loss in specific surface area. This work is also aimed at utilizing neutron and synchrotron x-ray characterization techniques to study and correlate multi-scale material properties and phenomena. Some of the most advanced

  5. Identification and characterization of a new zirconium hydride; Identification et caracterisation d'un nouvel hydrure de zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhao; Morniroli, J.P.; Legris, A.; Thuinet, L. [Universite des Sciences et Technologies de Lille, USTL, ENSCL, CNRS, 59 - Villeneuve d' Ascq (France); Zhao, Zhao; Blat-Yrieix, M.; Ambard, A.; Legras, L. [Electricite de France (EDF/RD), Centre des Renardieres, 77 - Moret sur Loing (France); Kihn, Y. [CEMES-CNRS, 31 - Toulouse (France)

    2007-07-01

    A study of hydrides characterization has been carried out in using the transmission electron microscopy technique. It has revealed the presence of small hydrides of acicular form whose length does not exceed 500 nm, among the zircaloy-4 samples hydrided by cathodic way. The electronic diffraction has shown that these small hydrides have a crystallographic structure different of those of the hydrides phases already index in literature. A more complete identification study has then been carried out. In combining the different electronic microscopy techniques (precession electronic micro diffraction and EELS) with ab initio calculations, a new hydride phase has been identified. It is called hydride {zeta}, is of trigonal structure with lattice parameters a{sub {zeta}} = a{sub {alpha}}{sub Zr} = 0.33 nm and c{sub {zeta}} 2c{sub {alpha}}{sub Zr} = 1.029 nm, its spatial group being P3m1. (O.M.)

  6. A deformation and thermodynamic model for hydride precipitation kinetics in spent fuel cladding

    International Nuclear Information System (INIS)

    Stout, R.B.

    1989-10-01

    Hydrogen is contained in the Zircaloy cladding of spent fuel rods from nuclear reactors. All the spent fuel rods placed in a nuclear waste repository will have a temperature history that decreases toward ambient; and as a result, most all of the hydrogen in the Zircaloy will eventually precipitate as zirconium hydride platelets. A model for the density of hydride platelets is a necessary sub-part for predicting Zircaloy cladding failure rate in a nuclear waste repository. A model is developed to describe statistically the hydride platelet density, and the density function includes the orientation as a physical attribute. The model applies concepts from statistical mechanics to derive probable deformation and thermodynamic functionals for cladding material response that depend explicitly on the hydride platelet density function. From this model, hydride precipitation kinetics depend on a thermodynamic potential for hydride density change and on the inner product of a stress tensor and a tensor measure for the incremental volume change due to hydride platelets. The development of a failure response model for Zircaloy cladding exposed to the expected conditions in a nuclear waste repository is supported by the US DOE Yucca Mountain Project. 19 refs., 3 figs

  7. Studies of hydride formation and superconductivity in hydrides of alloys Th-M /M = La, Y, Ce, Zr and Bi/

    Science.gov (United States)

    Oesterreicher, H.; Clinton, J.; Misroch, M.

    1977-01-01

    In order to gain a better insight into both the unusual composition of ThH15 and its superconductivity, an experimental study was conducted to assess the influence of partial replacement of Th in Th4H15 by elements which allow for a systematic alteration of spatial and electronic effects. For this purpose, substituent elements with the same number of valence electrons (4) but of smaller size (Zr) as well as elements with a smaller number of valence electrons (3) and either larger (La) or smaller size (Y) were selected. A few data with Ce and Bi as substituent atoms are also included. The matrix alloys for hydriding were obtained by induction melting under Ar in water-cooled Cu boats. Superconducting transition temperatures are found to decrease on substitution for Th in Th4H15. Hydrides derived from LaH3 by substitution for La by Th do not become superconducting. It is suggested that superconductivity in Th4H15 is connected with a deviation from the exact stoichiometry of Th4H15. A model of unsatisfied valencies may be of more general validity in predicting superconductivity.

  8. Anion and cation diffusion in barium titanate and strontium titanate

    International Nuclear Information System (INIS)

    Kessel, Markus Franz

    2012-01-01

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO 3 single crystals has been studied by means of 18 O 2 / 16 O 2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial pressure and temperature. The

  9. Acute respiratory failure caused by aspiration of high density barium: A case report

    International Nuclear Information System (INIS)

    Park, Ki Soon; Jung, Eun A; Yang, Ik; Lee, Yul; Chung, Soo Young

    1994-01-01

    Accidental aspiration of barium contrast medium during the upper gastrointestinal study can occur in patients with swallowing disorder, especially in the elderly patients. We experienced a case of respiratory failure followed by death within a few hours in 85 year-old patient after barium aspiration

  10. Integrated treatment of acid mine drainage using cryptocrystalline magnesite and barium chloride

    CSIR Research Space (South Africa)

    Masindi, Vhahangwele

    2017-08-01

    Full Text Available the formation of barium sulphate. Batch experimental approach was adopted and the documented optimum conditions for both cryptocrystalline magnesite and barium salts were used. This was 60 mins for pre-treatment and 60 mins for polishing the residual sulphate...

  11. Effect of barium doping on the physical properties of zinc oxide ...

    Indian Academy of Sciences (India)

    2016-06-09

    Jun 9, 2016 ... Abstract. The aim of this work is to study the effect of barium (Ba) doping on the optical, morphological and structural properties of ZnO nanoparticles. Undoped and Ba-doped ZnO have been successfully synthesized via sonochemical method using zinc nitrate, hexamethylenetetramine (HMT) and barium ...

  12. The effect of barium on perceptions of taste intensity and palatability

    Science.gov (United States)

    Dietsch, Angela M.; Solomon, Nancy Pearl; Steele, Catriona M.; Pelletier, Cathy A.

    2015-01-01

    Purpose Barium may affect the perception of taste intensity and palatability. Such differences are important considerations in the selection of dysphagia assessment strategies and interpretation of results. Methods Eighty healthy women grouped by age (younger, older) and genetic taste status (supertaster, non-taster) rated intensity and palatability for seven tastants prepared in deionized water with and without 40% w/v barium: non-carbonated and carbonated water, diluted ethanol, and high concentrations of citric acid (sour), sodium chloride (salty), caffeine (bitter) and sucrose (sweet). Mixed model analyses explored the effects of barium, taster status, and age on perceived taste intensity and acceptability of stimuli. Results Barium was associated with lower taste intensity ratings for sweet, salty, and bitter tastants, higher taste intensity in carbonated water, and lower palatability in water, sweet, sour, and carbonated water. Older subjects reported lower palatability (all barium samples, sour) and higher taste intensity scores (ethanol, sweet, sour) compared to younger subjects. Supertasters reported higher taste intensity (ethanol, sweet, sour, salty, bitter) and lower palatability (ethanol, salty, bitter) than non-tasters. Refusal rates were highest for younger subjects and supertasters, and for barium (regardless of tastant), bitter, and ethanol. Conclusions Barium suppressed the perceived intensity of some tastes and reduced palatability. These effects are more pronounced in older subjects and supertasters, but younger supertasters are least likely to tolerate trials of barium and strong tastant solutions. PMID:24037100

  13. New efficient catalyst for ammonia synthesis: barium-promoted cobalt on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus

    2002-01-01

    Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia......Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia...

  14. Thermal evolution of exchange interactions in lightly doped barium hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Trukhanov, S.V., E-mail: truhanov@ifttp.bas-net.by [National University of Science and Technology MISiS, Leninsky Prospekt, 4, 119049 Moscow (Russian Federation); SSPA “Scientific and practical materials research centre of NAS of Belarus”, P. Brovki Str., 19, 220072 Minsk, Belorussia (Belarus); Trukhanov, A.V. [National University of Science and Technology MISiS, Leninsky Prospekt, 4, 119049 Moscow (Russian Federation); SSPA “Scientific and practical materials research centre of NAS of Belarus”, P. Brovki Str., 19, 220072 Minsk, Belorussia (Belarus); Kostishyn, V.G.; Panina, L.V. [National University of Science and Technology MISiS, Leninsky Prospekt, 4, 119049 Moscow (Russian Federation); Turchenko, V.A. [Joint Institute for Nuclear Research, Joliot-Curie Str., 141980 Dubna (Russian Federation); Donetsk Institute of Physics and Technology named after A.A. Galkin of the NAS of Ukraine, 72 R.Luxemburg Str., 83114 Donetsk (Ukraine); Kazakevich, I.S. [SSPA “Scientific and practical materials research centre of NAS of Belarus”, P. Brovki Str., 19, 220072 Minsk, Belorussia (Belarus); Trukhanov, An.V. [National University of Science and Technology MISiS, Leninsky Prospekt, 4, 119049 Moscow (Russian Federation); SSPA “Scientific and practical materials research centre of NAS of Belarus”, P. Brovki Str., 19, 220072 Minsk, Belorussia (Belarus); Trukhanova, E.L.; Natarov, V.O. [SSPA “Scientific and practical materials research centre of NAS of Belarus”, P. Brovki Str., 19, 220072 Minsk, Belorussia (Belarus); Balagurov, A.M. [Joint Institute for Nuclear Research, Joliot-Curie Str., 141980 Dubna (Russian Federation)

    2017-03-15

    The lightly doped BaFe{sub 12−x}D{sub x}O{sub 19} (D=Al{sup 3+}, In{sup 3+}; x=0.1 and 0.3) polycrystalline hexaferrite samples have been investigated by powder neutron diffractometry as well as by vibration sample magnetometry in a wide temperature range from 4 K up to 740 K and in magnetic field up to 14 T to establish the nature of Fe{sup 3+}(Al{sup 3+}, In{sup 3+}) – O{sup 2-} - Fe{sup 3+}(Al{sup 3+}, In{sup 3+}) indirect exchange interactions. The crystal structure features such as the ionic coordinates and lattice parameters have been defined and Rietveld refined. The Invar effect has been observed in low temperature range below 150 K. It was explained by the thermal oscillation anharmonicity of ions. It is established that the ferrimagnet-paramagnet phase transition is a standard second-order one. From the macroscopic magnetization measurement the Curie temperature and ordered magnetic moment per nominal iron ion are obtained. From the microscopic diffraction measurement the magnetic moments at all the nonequivalent ionic positions and total magnetic moment per iron ion have been obtained at different temperatures down to 4 K. The light diamagnetic doping mechanism and magnetic structure model are proposed. The effect of light diamagnetic doping on nature of Fe{sup 3+}(Al{sup 3+}, In{sup 3+}) – O{sup 2-} - Fe{sup 3+}(Al{sup 3+}, In{sup 3+}) indirect exchange interactions with temperature increase is discussed. - Highlights: • Crystal structure for lightly doped barium hexaferrites was investigated. • Atomic coordinates and lattice parameters were Rietveld refined. • Magnetic properties for lightly doped barium hexaferrites was investigated. • Magnetic structure for lightly doped barium hexaferrites was investigated. • Magnetic moments at different position and total moment per iron ion were defined.

  15. Evidence against Barium in the Mushroom Trogia venenata as a Cause of Sudden Unexpected Deaths in Yunnan, China

    OpenAIRE

    Zhang, Ying; Li, Yanchun; Wu, Gang; Feng, Bang; Yoell, Shanze; Yu, Zefen; Zhang, Keqin; Xu, Jianping

    2012-01-01

    This study examined barium concentrations in the mushroom Trogia venenata, the leading culprit for sudden unexpected deaths in Yunnan, southwest China. We found that barium concentrations in T. venenata from Yunnan were low and comparable to other foods, inconsistent with barium concentrations in this mushroom as a significant contributor to these deaths.

  16. Evidence against barium in the mushroom Trogia venenata as a cause of sudden unexpected deaths in Yunnan, China.

    Science.gov (United States)

    Zhang, Ying; Li, Yanchun; Wu, Gang; Feng, Bang; Yoell, Shanze; Yu, Zefen; Zhang, Keqin; Xu, Jianping

    2012-12-01

    This study examined barium concentrations in the mushroom Trogia venenata, the leading culprit for sudden unexpected deaths in Yunnan, southwest China. We found that barium concentrations in T. venenata from Yunnan were low and comparable to other foods, inconsistent with barium concentrations in this mushroom as a significant contributor to these deaths.

  17. Room-temperature biosynthesis of ferroelectric barium titanate nanoparticles.

    Science.gov (United States)

    Bansal, Vipul; Poddar, Pankaj; Ahmad, Absar; Sastry, Murali

    2006-09-13

    The syntheses of inorganic materials by biological systems is characterized by processes that occur close to ambient temperatures, pressures, and neutral pH, as is exemplified by biosilicification and biomineralization processes in nature. Conversely, laboratory-based syntheses of oxide materials often require extremes of temperature and pressure. We have shown here the extracellular, room-temperature biosynthesis of 4-5 nm ternary oxide nanoparticles such as barium titanate (BT) using a fungus-mediated approach. The tetragonality as well as a lowered Curie transition temperature in sub-10 nm particles was established, and the ferroelectricity in these particles was shown using Kelvin probe microscopy.

  18. Barium strontium titanate powders prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Brankovic, G.; Brankovic, Z.; Goes, M.S.; Paiva-Santos, C.O.; Cilense, M.; Varela, J.A.; Longo, E.

    2005-01-01

    Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders were submicronic, consisting of spherical, polycrystalline particles, with internal nanocrystalline structure. Crystallite size of 10 nm, calculated using Rietveld refinement, is in a good agreement with results of HRTEM

  19. Radium and barium in the Amazon River system

    International Nuclear Information System (INIS)

    Moore, W.S.; Edmond, J.M.

    1984-01-01

    Data for 226 Ra and 228 Ra in the Amazon River system show that the activity of each radium isotope is strongly correlated with barium concentrations. Two trends are apparent, one for rivers which drain shield areas and another for all other rivers. These data suggest that there has been extensive fractionation of U, Th, and Ba during weathering in the Amazon basin. The 226 Ra data fit a flux model for the major ions indicating that 226 Ra behaves conservatively along the main channel of the Amazon River

  20. Enhanced flexoelectricity through residual ferroelectricity in barium strontium titanate

    International Nuclear Information System (INIS)

    Garten, Lauren M.; Trolier-McKinstry, Susan

    2015-01-01

    Residual ferroelectricity is observed in barium strontium titanate ceramics over 30 °C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient leads to strain gradient-induced poling or flexoelectric poling. This was observed by the development of a remanent polarization in flexoelectric measurements, an induced d 33 piezoelectric response even after the strain gradient was removed, and the production of an internal bias of 9 kV m −1 . It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response

  1. Enhanced flexoelectricity through residual ferroelectricity in barium strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Garten, Lauren M., E-mail: lmg309@psu.edu; Trolier-McKinstry, Susan [Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-03-07

    Residual ferroelectricity is observed in barium strontium titanate ceramics over 30 °C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient leads to strain gradient-induced poling or flexoelectric poling. This was observed by the development of a remanent polarization in flexoelectric measurements, an induced d{sub 33} piezoelectric response even after the strain gradient was removed, and the production of an internal bias of 9 kV m{sup −1}. It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response.

  2. Enhanced flexoelectricity through residual ferroelectricity in barium strontium titanate

    Science.gov (United States)

    Garten, Lauren M.; Trolier-McKinstry, Susan

    2015-03-01

    Residual ferroelectricity is observed in barium strontium titanate ceramics over 30 °C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient leads to strain gradient-induced poling or flexoelectric poling. This was observed by the development of a remanent polarization in flexoelectric measurements, an induced d33 piezoelectric response even after the strain gradient was removed, and the production of an internal bias of 9 kV m-1. It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response.

  3. Quantification and characterization of zirconium hydrides in Zircaloy-4 by the image analysis method

    International Nuclear Information System (INIS)

    Zhang, J.H.; Groos, M.; Bredel, T.; Trotabas, M.; Combette, P.

    1992-01-01

    The image analysis method is used to determine the hydrogen content in specimens of Zircaloy-4. Two parameters, surface density of hydride, S v , and degree of orientation, Ω, are defined to represent separately the hydrogen content and the orientation of hydrides. By analysing the stress-relieved Zircaloy-4 specimens with known hydrogen content from 100 to 1000 ppm, a relationship is established between the parameter S v and the hydrogen content when the magnifications of the optical microscope are 1000 and 250. The degree of orientation for the hydride in the stress-relieved Zircaloy-4 cladding is about 0.3. (orig.)

  4. Analytical control of production of As, P, Si, B hydrides and the mixtures on their basis

    International Nuclear Information System (INIS)

    Ivanova, N.T.; Vislykh, N.A.; Voevodina, V.V.

    1989-01-01

    Highly sensitive and selective detectors which are in the basis of some analytical devices, such as chromatograph Tzvet 500G attachment POU-80, gigrometer Enisej gas analyzer Platon that permit to control the production of As, P, Si, B hydrides, are tested. The techniques of tetermination of constant gases, general carbon, moisture in the mixtures based on As, P, Si, B hydrides with diluting gases (H 2 , He, Ar) as well as hydrides in them and in the air of working premises, are suggested

  5. Solid hydrides as hydrogen storage reservoirs; Hidruros solidos como acumuladores de hidrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.; Sanchez, C.; Friedrichs, O.; Ares, J. R.; Leardini, F.; Bodega, J.; Fernandez, J. F.

    2010-07-01

    Metal hydrides as hydrogen storage materials are briefly reviewed in this paper. Fundamental properties of metal-hydrogen (gas) system such as Pressure-Composition-Temperature (P-C-T) characteristics are discussed on the light of the metal-hydride thermodynamics. Attention is specially paid to light metal hydrides which might have application in the car and transport sector. The pros and cons of MgH{sub 2} as a light material are outlined. Researches in course oriented to improve the behaviour of MgH{sub 2} are presented. Finally, other very promising alternative materials such as Al compounds (alanates) or borohydrides as light hydrogen accumulators are also considered. (Author)

  6. Thermodynamics and statistical mechanics of some hydrides of the lanthanides and actinides

    International Nuclear Information System (INIS)

    Mintz, M.H.

    1976-06-01

    This work deals mainly with the thermodynamic and physical properties of the hydrides of the lanthanides and actinides. In addition, statistical models have been developed and applied to metal-hydrogen systems. A kinetic study of the uranium-hydrogen system was performed. The thermodynamic properties of the hydrides of neptunium, thorium, praseodymium, neodymium, samarium and europium were determined. In addition the samarium-europium-hydrogen ternary system was investigated. Moessbauer effect measurements of cubic neptunium hydrides were interpreted according to a model presented. A comparison. (author)

  7. Study of factors affecting a combustion method for determining carbon in lithium hydride

    International Nuclear Information System (INIS)

    Barringer, R.E.; Thornton, R.E.

    1975-09-01

    An investigation has been made of the factors affecting a combustion method for the determination of low levels (300 to 15,000 micrograms/gram) of carbon in highly reactive lithium hydride. Optimization of the procedure with available equipment yielded recoveries of 90 percent, with a limit of error (0.95) of +-39 percent relative for aliquants containing 35 to 55 micrograms of carbon (500 to 800 micrograms of carbon per gram of lithium hydride sample). Sample preparation, thermal decomposition of the hydride, final ignition of the carbon, and carbon-measurement steps were studied, and a detailed procedure was developed. (auth)

  8. Study on an innovative fast reactor utilizing hydride neutron absorber - Final report of phase I study

    International Nuclear Information System (INIS)

    Konashi, K.; Iwasaki, T.; Itoh, K.; Hirai, M.; Sato, J.; Kurosaki, K.; Suzuki, A.; Matsumura, Y.; Abe, S.

    2010-01-01

    These days, the demand to use nuclear resources efficiently is growing for long-term energy supply and also for solving the green house problem. It is indispensable to develop technologies to reduce environmental load with the nuclear energy supply for sustainable development of human beings. In this regard, the development of the fast breeder reactor (FBR) is preferable to utilize nuclear resources effectively and also to burn minor actinides which possess very long toxicity for more than thousands years if they are not extinguished. As one of the FBR developing works in Japan this phase I study started in 2006 to introduce hafnium (Hf) hydride and Gadolinium-Zirconium (Gd-Zr) hydride as new control materials in FBR. By adopting them, the FBR core control technology is improved by two ways. One is extension of control rod life time by using long life Hf hydride which leads to reduce the fabrication and disposal cost and the other is reduction of the excess reactivity by adopting Gd-Zr hydride which leads to reduce the number of control rods and simplifies the core upper structure. This three year study was successfully completed and the following results were obtained. The core design was performed to examine the applicability of the Hf hydride absorber to Japanese Sodium Fast Reactor (JSFR) and it is clarified that the control rod life time can be prolonged to 6 years by adopting Hf hydride and the excess reactivity of the beginning of the core cycle can be reduced to half and the number of the control rods is also reduced to half by using the Gd-Zr hydride burnable poison. The safety analyses also certified that the core safety can be maintained with the same reliability of JSFR Hf hydride and Gd-Zr hydride pellets were fabricated in good manner and their basic features for design use were measured by using the latest devices such as SEM-EDX. In order to reduce the hydrogen transfer through the stainless steel cladding a new technique which shares calorizing

  9. The storage of hydrogen in the form of metal hydrides: An application to thermal engines

    Science.gov (United States)

    Gales, C.; Perroud, P.

    1981-01-01

    The possibility of using LaNi56, FeTiH2, or MgH2 as metal hydride storage sytems for hydrogen fueled automobile engines is discussed. Magnesium copper and magnesium nickel hydrides studies indicate that they provide more stable storage systems than pure magnesium hydrides. Several test engines employing hydrogen fuel have been developed: a single cylinder motor originally designed for use with air gasoline mixture; a four-cylinder engine modified to run on an air hydrogen mixture; and a gas turbine.

  10. Barium sulfate suspension as a negative oral contrast agent for MR imaging

    International Nuclear Information System (INIS)

    Li, K.C.P.; Tart, R.P.; Fitzsimmons, J.R.; Storm, B.; Mao, J.

    1989-01-01

    Proton spectroscopy with linewidth measurements and MR imaging were performed on various commercially available barium sulfate suspensions as well as inorganic sulfates and barium salts. Approximately 500 mL of 20%, 40%, 60%, and 70% wt/wt single-contrast oral barium sulfate suspensions were administered to four normal volunteers, and MR imaging was performed with both a 1.5-T and a 0.15-T MR imager. As much as 80% of the small bowel and the entire colon were well visualized with the 60% or 70% wt/wt single-contrast barium sulfate suspensions. The authors conclude that barium sulfate suspensions are useful as oral MR contrast agents

  11. Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining

    International Nuclear Information System (INIS)

    Andrade, M.C.; Assis, J.T.; Pereira, F.R.

    2009-01-01

    A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO 3 formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

  12. Centrifugal Jet Spinning for Highly Efficient and Large-scale Fabrication of Barium Titanate Nanofibers.

    Science.gov (United States)

    Ren, Liyun; Kotha, Shiva P

    2014-02-15

    The centrifugal jet spinning (CJS) method has been developed to enable large-scale synthesis of barium titanate nanofibers. Barium titanate nanofibers with fiber diameters down to 50 nm and grain sizes around 25 nm were prepared with CJS by spinning a sol-gel solution of barium titanate and poly(vinylpyrrolidone) with subsequent heat treatment at 850 °C. XRD and FTIR analysis demonstrated high purity and tetragonal perovskite structured barium titanate nanofibers. SEM and TEM images confirm the continuous high aspect ratio structure of barium titanate nanofibers after heat treatment. It is demonstrated that the CJS technique offers a highly efficient method for large-scale fabrication of ceramic nanofibers at production rates of up to 0.3 gram/minute.

  13. Prospective comparison of double contrast barium enema plus flexible sigmoidoscopy v colonoscopy in rectal bleeding: barium enema v colonoscopy in rectal bleeding.

    OpenAIRE

    Irvine, E J; O'Connor, J; Frost, R A; Shorvon, P; Somers, S; Stevenson, G W; Hunt, R H

    1988-01-01

    Rectal bleeding often heralds serious colonic disease. The literature suggests that colonoscopy is superior to barium enema plus sigmoidoscopy, although no good comparative studies exist. Seventy one patients with overt rectal bleeding had prospectively flexible sigmoidoscopy, double contrast barium enema and colonoscopy completed independently. Against the gold standard, the sensitivity and specificity of colonoscopy were 0.69 and 0.78 respectively for a spectrum of colonic lesions, while fo...

  14. Evaluation of gastrointestinal tract transit times using barium-impregnated polyethylene spheres and barium sulfate suspension in a domestic pigeon (Columba livia) model.

    Science.gov (United States)

    Bloch, Rebecca A; Cronin, Kimberly; Hoover, John P; Pechman, Robert D; Payton, Mark E

    2010-03-01

    Barium impregnated polyethylene spheres (BIPS) are used in small animal medicine as an alternative to barium sulfate for radiographic studies of the gastrointestinal tract. To determine the usefulness of BIPS as an alternative to barium suspension in measuring gastrointestinal (GI) transit time for avian species, ventrodorsal radiographs were used to follow the passage of BIPS and 30% barium sulfate suspension through the GI tracts of domestic pigeons (Columba livia). Gastrointestinal transit times of thirty 1.5-mm BIPS administered in moistened gelatin capsules and 30% barium sulfate suspension gavaged into the crop were compared in 6 pigeons. Although the barium suspension passed out of the GI tract of all pigeons within 24 hours, the 1.5-mm BIPS remained in the ventriculus for 368.0 +/- 176.8 hours and did not clear the GI tract for 424.0 +/- 204.6 hours. Although the times for passage of BIPS and 30% barium sulfate suspension from the crop into the ventriculus were not significantly different (P = .14), the times for passage of BIPS from the ventriculus into the large intestine-cloaca and for clearance from the GI tract of the pigeons were significantly longer (P barium sulfate suspension. From the results of this study, we conclude that BIPS are not useful for radiographically evaluating GI transit times in pigeons and are unlikely to be useful in other avian species that have a muscular ventriculus. BIPS may or may not be useful for evaluating GI transit times in species that lack a muscular ventriculus.

  15. Hydrogen Storage Engineering Center of Excellence Metal Hydride Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Motyka, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-05-31

    The Hydrogen Storage Engineering Center of Excellence (HSECoE) was established in 2009 by the U.S. Department of Energy (DOE) to advance the development of materials-based hydrogen storage systems for hydrogen-fueled light-duty vehicles. The overall objective of the HSECoE is to develop complete, integrated system concepts that utilize reversible metal hydrides, adsorbents, and chemical hydrogen storage materials through the use of advanced engineering concepts and designs that can simultaneously meet or exceed all the DOE targets. This report describes the activities and accomplishments during Phase 1 of the reversible metal hydride portion of the HSECoE, which lasted 30 months from February 2009 to August 2011. A complete list of all the HSECoE partners can be found later in this report but for the reversible metal hydride portion of the HSECoE work the major contributing organizations to this effort were the United Technology Research Center (UTRC), General Motors (GM), Pacific Northwest National Laboratory (PNNL), the National Renewable Energy Laboratory (NREL) and the Savannah River National Laboratory (SRNL). Specific individuals from these and other institutions that supported this effort and the writing of this report are included in the list of contributors and in the acknowledgement sections of this report. The efforts of the HSECoE are organized into three phases each approximately 2 years in duration. In Phase I, comprehensive system engineering analyses and assessments were made of the three classes of storage media that included development of system level transport and thermal models of alternative conceptual storage configurations to permit detailed comparisons against the DOE performance targets for light-duty vehicles. Phase 1 tasks also included identification and technical justifications for candidate storage media and configurations that should be capable of reaching or exceeding the DOE targets. Phase 2 involved bench-level testing and

  16. DEVELOPMENT OF A FABRICATION PROCESS FOR SOL-GEL/METAL HYDRIDE COMPOSITE GRANULES

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, E; Eric Frickey, E; Leung Heung, L

    2004-02-23

    An external gelation process was developed to produce spherical granules that contain metal hydride particles in a sol-gel matrix. Dimensionally stable granules containing metal hydrides are needed for applications such as hydrogen separation and hydrogen purification that require columns containing metal hydrides. Gases must readily flow through the metal hydride beds in the columns. Metal hydrides reversibly absorb and desorb hydrogen and hydrogen isotopes. This is accompanied by significant volume changes that cause the metal hydride to break apart or decrepitate. Repeated cycling results in very fine metal hydride particles that are difficult to handle and contain. Fine particles tend to settle and pack making it more difficult to flow gases through a metal hydride bed. Furthermore, the metal hydrides can exert a significant force on the containment vessel as they expand. These problems associated with metal hydrides can be eliminated with the granulation process described in this report. Small agglomerates of metal hydride particles and abietic acid (a pore former) were produced and dispersed in a colloidal silica/water suspension to form the feed slurry. Fumed silica was added to increase the viscosity of the feed slurry which helped to keep the agglomerates in suspension. Drops of the feed slurry were injected into a 27-foot tall column of hot ({approx}70 C), medium viscosity ({approx}3000 centistokes) silicone oil. Water was slowly evaporated from the drops as they settled. The drops gelled and eventually solidified to form spherical granules. This process is referred to as external gelation. Testing was completed to optimize the design of the column, the feed system, the feed slurry composition, and the operating parameters of the column. The critical process parameters can be controlled resulting in a reproducible fabrication technique. The residual silicone oil on the surface of the granules was removed by washing in mineral spirits. The granules were

  17. Anion and cation diffusion in barium titanate and strontium titanate; Anionen- und Kationendiffusion in Barium- und Strontiumtitanat

    Energy Technology Data Exchange (ETDEWEB)

    Kessel, Markus Franz

    2012-12-19

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO{sub 3} single crystals has been studied by means of {sup 18}O{sub 2}/{sup 16}O{sub 2} isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial

  18. Comparison of delayed hydride cracking behavior of two zirconium alloys

    International Nuclear Information System (INIS)

    Ponzoni, L.M.E.; Mieza, J.I.; De Las Heras, E.; Domizzi, G.

    2013-01-01

    Delayed hydride cracking (DHC) is an important failure mechanism that may occur in Zr alloys during service in water-cooled reactors. Two conditions must be attained to initiate DHC from a crack: the stress intensity factor must be higher than a threshold value called K IH and, hydrogen concentration must exceed a critical value. Currently the pressure tubes for CANDU reactor are fabricated from Zr–2.5Nb. In this paper the critical hydrogen concentration for DHC and the crack velocity of a developmental pressure tube, Excel, was evaluated and compared with that of Zr–2.5Nb. The DHC velocity values measured in Excel were higher than usually reported in Zr–2.5Nb. Due to the higher hydrogen solubility limits in Excel, its critical hydrogen concentration for DHC initiation is 10–50 wppm over that of Zr–2.5Nb in the range of 150–300 °C

  19. Modeling of hydride precipitation and re-orientation

    Energy Technology Data Exchange (ETDEWEB)

    Tikare, Veena [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weck, Philippe F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, John Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-18

    In this report, we present a thermodynamic-­based model of hydride precipitation in Zr-based claddings. The model considers the state of the cladding immediately following drying, after removal from cooling-pools, and presents the evolution of precipitate formation upon cooling as follows: The pilgering process used to form Zr-based cladding imparts strong crystallographic and grain shape texture, with the basal plane of the hexagonal α-Zr grains being strongly aligned in the rolling-­direction and the grains are elongated with grain size being approximately twice as long parallel to the rolling direction, which is also the long axis of the tubular cladding, as it is in the orthogonal directions.

  20. Comparison of delayed hydride cracking behavior of two zirconium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ponzoni, L.M.E. [CNEA – Centro Atómico Constituyentes, Hidrógeno en Materiales, Av. Gral. Paz 1499, San Martín (B1650KNA), Bs. As. (Argentina); Mieza, J.I. [CNEA – Centro Atómico Constituyentes, Hidrógeno en Materiales, Av. Gral. Paz 1499, San Martín (B1650KNA), Bs. As. (Argentina); Instituto Sabato, UNSAM–CNEA, Av. Gral. Paz 1499, San Martín (B1650KNA), Bs. As. (Argentina); De Las Heras, E. [CNEA – Centro Atómico Constituyentes, Hidrógeno en Materiales, Av. Gral. Paz 1499, San Martín (B1650KNA), Bs. As. (Argentina); Domizzi, G., E-mail: domizzi@cnea.gov.ar [CNEA – Centro Atómico Constituyentes, Hidrógeno en Materiales, Av. Gral. Paz 1499, San Martín (B1650KNA), Bs. As. (Argentina); Instituto Sabato, UNSAM–CNEA, Av. Gral. Paz 1499, San Martín (B1650KNA), Bs. As. (Argentina)

    2013-08-15

    Delayed hydride cracking (DHC) is an important failure mechanism that may occur in Zr alloys during service in water-cooled reactors. Two conditions must be attained to initiate DHC from a crack: the stress intensity factor must be higher than a threshold value called K{sub IH} and, hydrogen concentration must exceed a critical value. Currently the pressure tubes for CANDU reactor are fabricated from Zr–2.5Nb. In this paper the critical hydrogen concentration for DHC and the crack velocity of a developmental pressure tube, Excel, was evaluated and compared with that of Zr–2.5Nb. The DHC velocity values measured in Excel were higher than usually reported in Zr–2.5Nb. Due to the higher hydrogen solubility limits in Excel, its critical hydrogen concentration for DHC initiation is 10–50 wppm over that of Zr–2.5Nb in the range of 150–300 °C.

  1. Delayed hydride cracking: theoretical model testing to predict cracking velocity

    International Nuclear Information System (INIS)

    Mieza, Juan I.; Vigna, Gustavo L.; Domizzi, Gladys

    2009-01-01

    Pressure tubes from Candu nuclear reactors as any other component manufactured with Zr alloys are prone to delayed hydride cracking. That is why it is important to be able to predict the cracking velocity during the component lifetime from parameters easy to be measured, such as: hydrogen concentration, mechanical and microstructural properties. Two of the theoretical models reported in literature to calculate the DHC velocity were chosen and combined, and using the appropriate variables allowed a comparison with experimental results of samples from Zr-2.5 Nb tubes with different mechanical and structural properties. In addition, velocities measured by other authors in irradiated materials could be reproduced using the model described above. (author)

  2. Final report for the DOE Metal Hydride Center of Excellence.

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Jay O.; Klebanoff, Leonard E.

    2012-01-01

    This report summarizes the R&D activities within the U.S. Department of Energy Metal Hydride Center of Excellence (MHCoE) from March 2005 to June 2010. The purpose of the MHCoE has been to conduct highly collaborative and multi-disciplinary applied R&D to develop new reversible hydrogen storage materials that meet or exceed DOE 2010 and 2015 system goals for hydrogen storage materials. The MHCoE combines three broad areas: mechanisms and modeling (which provide a theoretically driven basis for pursuing new materials), materials development (in which new materials are synthesized and characterized) and system design and engineering (which allow these new materials to be realized as practical automotive hydrogen storage systems). This Final Report summarizes the organization and execution of the 5-year research program to develop practical hydrogen storage materials for light duty vehicles. Major results from the MHCoE are summarized, along with suggestions for future research areas.

  3. Interface Enthalpy-Entropy Competition in Nanoscale Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Nicola Patelli

    2018-01-01

    Full Text Available We analyzed the effect of the interfacial free energy on the thermodynamics of hydrogen sorption in nano-scaled materials. When the enthalpy and entropy terms are the same for all interfaces, as in an isotropic bi-phasic system, one obtains a compensation temperature, which does not depend on the system size nor on the relative phase abundance. The situation is different and more complex in a system with three or more phases, where the interfaces have different enthalpy and entropy. We also consider the possible effect of elastic strains on the stability of the hydride phase and on hysteresis. We compare a simple model with experimental data obtained on two different systems: (1 bi-phasic nanocomposites where ultrafine TiH2 crystallite are dispersed within a Mg nanoparticle and (2 Mg nanodots encapsulated by different phases.

  4. Parametrization of a reactive force field for aluminum hydride.

    Science.gov (United States)

    Ojwang, J G O; van Santen, Rutger A; Kramer, Gert Jan; van Duin, Adri C T; Goddard, William A

    2009-07-28

    A reactive force field, REAXFF, for aluminum hydride has been developed based on density functional theory (DFT) derived data. REAXFF(AlH(3)) is used to study the dynamics governing hydrogen desorption in AlH(3). During the abstraction process of surface molecular hydrogen charge transfer is found to be well described by REAXFF(AlH(3)). Results on heat of desorption versus cluster size show that there is a strong dependence of the heat of desorption on the particle size, which implies that nanostructuring enhances desorption process. In the gas phase, it was observed that small alane clusters agglomerated into a bigger cluster. After agglomeration molecular hydrogen was desorbed from the structure. This thermodynamically driven spontaneous agglomeration followed by desorption of molecular hydrogen provides a mechanism on how mobile alane clusters can facilitate the mass transport of aluminum atoms during the thermal decomposition of NaAlH(4).

  5. Shielding efficiency of metal hydrides and borohydrides in fusion reactors

    DEFF Research Database (Denmark)

    Singh, Vishvanath P.; Badiger, Nagappa M.; Gerward, Leif

    2016-01-01

    at energies 0.015 MeV to15 MeV, and for penetration depths up to 40 mean free paths. Fast-neutron shielding efficiency has been characterized by the effective neutron removal cross-section. It is shown that ZrH2 and VH2 are very good shielding materials for gamma rays and fast neutrons due to their suitable......Mass attenuation coefficients, mean free paths and exposure buildup factors have been used to characterize the shielding efficiency of metal hydrides and borohydrides, with high density of hydrogen. Gamma ray exposure buildup factors were computed using five-parameter geometric progression fitting...... combination of low-and high-Z elements. The present work should be useful for the selection and design of blankets and shielding, and for dose evaluation for components in fusion reactors....

  6. Hydride transport vessel vibration and shock test report

    Energy Technology Data Exchange (ETDEWEB)

    Tipton, D.G.

    1998-06-01

    Sandia National Laboratories performed vibration and shock testing on a Savannah River Hydride Transport Vessel (HTV) which is used for bulk shipments of tritium. This testing is required to qualify the HTV for transport in the H1616 shipping container. The main requirement for shipment in the H1616 is that the contents (in this case the HTV) have a tritium leak rate of less than 1x10{sup {minus}7} cc/sec after being subjected to shock and vibration normally incident to transport. Helium leak tests performed before and after the vibration and shock testing showed that the HTV remained leaktight under the specified conditions. This report documents the tests performed and the test results.

  7. Hydride transport vessel vibration and shock test report

    International Nuclear Information System (INIS)

    Tipton, D.G.

    1998-06-01

    Sandia National Laboratories performed vibration and shock testing on a Savannah River Hydride Transport Vessel (HTV) which is used for bulk shipments of tritium. This testing is required to qualify the HTV for transport in the H1616 shipping container. The main requirement for shipment in the H1616 is that the contents (in this case the HTV) have a tritium leak rate of less than 1x10 -7 cc/sec after being subjected to shock and vibration normally incident to transport. Helium leak tests performed before and after the vibration and shock testing showed that the HTV remained leaktight under the specified conditions. This report documents the tests performed and the test results

  8. Modelling zirconium hydrides using the special quasirandom structure approach

    KAUST Repository

    Wang, Hao

    2013-01-01

    The study of the structure and properties of zirconium hydrides is important for understanding the embrittlement of zirconium alloys used as cladding in light water nuclear reactors. Simulation of the defect processes is complicated due to the random distribution of the hydrogen atoms. We propose the use of the special quasirandom structure approach as a computationally efficient way to describe this random distribution. We have generated six special quasirandom structure cells based on face centered cubic and face centered tetragonal unit cells to describe ZrH2-x (x = 0.25-0.5). Using density functional theory calculations we investigate the mechanical properties, stability, and electronic structure of the alloys. © the Owner Societies 2013.

  9. Hydride phase dissolution enthalpy in neutron irradiated Zircaloy-4

    International Nuclear Information System (INIS)

    Vizcaino, Pablo; Banchik, Abraham D.

    2003-01-01

    The differential calorimetric technique has been applied to measure the dissolution enthalpy, ΔH irrad δ→α , of zirconium hydrides precipitated in structural components removed from the Argentine Atucha 1 PHWR nuclear power plant after 10.3 EFPY. An average value of ΔH irrad δ→α = 5 kJ/mol H was obtained after the first calorimetric run. That value is seven times lower than the value of ΔH δ→α = 37.7 kJ/mol H recently determined in Zircaloy-4 specimens taken from similar unirradiated structural components using the same calorimetric technique, [1]. Post-irradiation thermal treatments gradually increase that low value towards the unirradiated value with increasing annealing temperature similar to that observed for TSSd irrad . Therefore the same H atom trapping mechanism during reactor operation already proposed to explain the evolution of TSSd irrad is also valid for Q irrad δ→α . As the ratio Q/ΔH is proportional to the number N H of H atoms precipitated as hydrides, the increment of Q irrad δ→α with the thermal treatment indicates that the value of N H also grows with the annealing reaching the value corresponding to the bulk H concentration when ΔH irrad δ→α ≅ 37 kJ/mol H. That is a direct indication that the post-irradiation thermal treatment releases the H atoms from their traps increasing the number of H atoms available to precipitate at the end of each calorimetric run and/or isothermal treatment. (author)

  10. Neutron diffraction studies of transition metal hydride complexes

    International Nuclear Information System (INIS)

    Koetzle, T.F.; Bau, R.

    1976-01-01

    Investigations of H 3 Ta(C 5 H 5 ) 2 (III), HW 2 (CO) 9 (NO) (IV), and HW 2 (CO) 8 (NO) (P(OCH 3 ) 3 ) (V) have been completed. Preliminary results are available for HFeCo 3 (CO) 9 [P(OCH 3 ) 3 ] 3 (VII). This work, together with studies of HMo 2 (C 5 H 5 ) 2 (CO) 4 (P(CH 3 ) 2 ) (VI) and [(C 2 H 5 ) 4 N] + [HCr 2 (CO) 10 ] - carried out at Argonne has led to some general observations on the geometry and the nature of bonding in these compounds. For example, in the structures of IV and V, both of which have bent W--H--W linkages (less than W--H--W in the range 125-130 0 ), there is conclusive evidence for the existence of a closed three-center W--H--W bond with significant metal-metal interaction. Such is the case, because extensions of the axial W--C and W--N bonds trans to the hydride intersect at a point near the center of the W--H--W triangle. The geometry of VI, which also contains a bent M--H--M bond, is consistent with that of IV and V. Bridging M--H bonds in these second- and third-row hydrides range in length from 1.85 to 1.89 A, compared to 1.75 A in the first-row polynuclear complex VII. For metals of corresponding rows, bridging M--H bonds are about 0.1 A longer than terminal bonds, which are classified as single covalent bonds

  11. Barium titanate core--gold shell nanoparticles for hyperthermia treatments.

    Science.gov (United States)

    FarrokhTakin, Elmira; Ciofani, Gianni; Puleo, Gian Luigi; de Vito, Giuseppe; Filippeschi, Carlo; Mazzolai, Barbara; Piazza, Vincenzo; Mattoli, Virgilio

    2013-01-01

    The development of new tools and devices to aid in treating cancer is a hot topic in biomedical research. The practice of using heat (hyperthermia) to treat cancerous lesions has a long history dating back to ancient Greece. With deeper knowledge of the factors that cause cancer and the transmissive window of cells and tissues in the near-infrared region of the electromagnetic spectrum, hyperthermia applications have been able to incorporate the use of lasers. Photothermal therapy has been introduced as a selective and noninvasive treatment for cancer, in which exogenous photothermal agents are exploited to achieve the selective destruction of cancer cells. In this manuscript, we propose applications of barium titanate core-gold shell nanoparticles for hyperthermia treatment against cancer cells. We explored the effect of increasing concentrations of these nanoshells (0-100 μg/mL) on human neuroblastoma SH-SY5Y cells, testing the internalization and intrinsic toxicity and validating the hyperthermic functionality of the particles through near infrared (NIR) laser-induced thermoablation experiments. No significant changes were observed in cell viability up to nanoparticle concentrations of 50 μg/mL. Experiments upon stimulation with an NIR laser revealed the ability of the nanoshells to destroy human neuroblastoma cells. On the basis of these findings, barium titanate core-gold shell nanoparticles resulted in being suitable for hyperthermia treatment, and our results represent a promising first step for subsequent investigations on their applicability in clinical practice.

  12. Synthesis of Barium Titanate Using Deep Eutectic Solvents.

    Science.gov (United States)

    Boston, Rebecca; Foeller, Philip Y; Sinclair, Derek C; Reaney, Ian M

    2017-01-03

    Novel synthetic routes to prepare functional oxides at lower temperatures are an increasingly important area of research. Many of these synthetic routes, however, use water as the solvent and rely on dissolution of the precursors, precluding their use with, for example, titanates. Here we present a low-cost solvent system as a means to rapidly create phase-pure ferroelectric barium titanate using a choline chloride-malonic acid deep eutectic solvent. This solvent is compatible with alkoxide precursors and allows for the rapid synthesis of nanoscale barium titanate powders at 950 °C. The phase and morphology were determined, along with investigation of the synthetic pathway, with the reaction proceeding via BaCl 2 and TiO 2 intermediates. The powders were also used to create sintered ceramics, which exhibit a permittivity maximum corresponding to a tetragonal-cubic transition at 112 °C, as opposed to the more conventional temperature of ∼120 °C. The lower-than-expected value for the ferro- to para-electric phase transition is likely due to undetectable levels of contaminants.

  13. Studies on Nano Barium Strontium Titanate/Cellulose Derivatives Composites

    Directory of Open Access Journals (Sweden)

    Y. Hamzeh

    2009-12-01

    Full Text Available Studies were carried out on the preparation and properties of the composites made from cellulose acetate butyrate and cellulose acetate propionate with various amounts of barium strontium titanate nano-particle. The nano-particles of barium strontium titanate (BST with formulation of Ba0.77Sr0.23TiO3 were made by sol-gel method and their purity and particle size were analyzed by X-ray diffraction (XRD. The composites were prepared with BST nano-particle loading of 10 to 50 vol%, and their distribution in the composites studied using SEM imaging. The dielectric constant of the composites was measured at 1 kHz and 100 kHz at room temperature. It was found that the adopted procedure produced dense and uniform composites. The dielectric constant of the composites increased with the solid contentof BST and followed the modified Lichtenecker equation. The increasing rate of dielectric constant with increased BST content was more pronounced for the BST/CAP composite. The dielectric constant of the composites decreased withincreasing the frequency which was more obvious at higher loading of BST nano-particle

  14. Barium titanate core – gold shell nanoparticles for hyperthermia treatments

    Science.gov (United States)

    FarrokhTakin, Elmira; Ciofani, Gianni; Puleo, Gian Luigi; de Vito, Giuseppe; Filippeschi, Carlo; Mazzolai, Barbara; Piazza, Vincenzo; Mattoli, Virgilio

    2013-01-01

    The development of new tools and devices to aid in treating cancer is a hot topic in biomedical research. The practice of using heat (hyperthermia) to treat cancerous lesions has a long history dating back to ancient Greece. With deeper knowledge of the factors that cause cancer and the transmissive window of cells and tissues in the near-infrared region of the electromagnetic spectrum, hyperthermia applications have been able to incorporate the use of lasers. Photothermal therapy has been introduced as a selective and noninvasive treatment for cancer, in which exogenous photothermal agents are exploited to achieve the selective destruction of cancer cells. In this manuscript, we propose applications of barium titanate core–gold shell nanoparticles for hyperthermia treatment against cancer cells. We explored the effect of increasing concentrations of these nanoshells (0–100 μg/mL) on human neuroblastoma SH-SY5Y cells, testing the internalization and intrinsic toxicity and validating the hyperthermic functionality of the particles through near infrared (NIR) laser-induced thermoablation experiments. No significant changes were observed in cell viability up to nanoparticle concentrations of 50 μg/mL. Experiments upon stimulation with an NIR laser revealed the ability of the nanoshells to destroy human neuroblastoma cells. On the basis of these findings, barium titanate core–gold shell nanoparticles resulted in being suitable for hyperthermia treatment, and our results represent a promising first step for subsequent investigations on their applicability in clinical practice. PMID:23847415

  15. Materials Synthesis Of Barium Hexa ferrite Used Local Natural Resources

    International Nuclear Information System (INIS)

    Ridwan; Sulungbudi, Grace Tj.; Mujamilah

    2003-01-01

    The magnetic materials of barium hexa ferrites, Ba O.6Fe 2 O 3 successfully synthesized by powder metallurgy method used local natural resources from materials waste of steel fabrication (HSM, CRM), waste of polymer fabrication (LK) as well as iron sands (PBA). These waste as well as iron sands were the main resources of iron oxide, Fe 2 O 3 . The barium oxide used in this experiments are from BaCO 3 product of Merck, and BaCO 4 which is commercially available in the market as barite. Phase identification by x-ray diffraction technique show the synthesized magnetic materials are agreed with the available commercial product, (SUMI). The energy product maximum (BH) max measured by vibrating sample magnetometer (VSM) for the samples used HSM-, CRM- and BaCO 3 as basic materials are 1.141 MGOe and 1.136 MGOe while SUMI is 1.142 MGOe. However for the samples made from LK-, PBA- used of BaCO 3 or CRM- with barite, the energy product maximum (BH) max are relatively lower than commercial product

  16. Prospects for the ORNL/TAMU Barium Fluoride Array

    Science.gov (United States)

    Townsend, Austin; McIntosh, Alan; Youngs, Mike; Mosby, Shea; Varner, Robert

    2016-09-01

    Understanding the symmetry energy in the nuclear equation of state is essential to understanding properties such as the structure of a neutron star or its gravitational collapse, leading to supernovae. It has been suggested that to better constrain the symmetry energy one can use the bremmstrahlung gamma rays emitted from the hot, dense nuclear matter in the early stages of heavy ion collisions. These gamma rays have the potential to provide a cleaner probe than the more traditional hadronic probes. To measure these bremmstrahlung photons, barium fluoride scintillation crystals were chosen for their ability to detect photons across a large energy range and for their inherent pulse shape discrimination properties. This summer, the detectors of the TAMU/ORNL barium fluoride array were tested in preparation for such an experiment. Signals from each detector were recorded individually for cosmic rays and radioactive source events. The full waveforms were digitized with flash ADCs. A selected set of detectors was assembled and tested with beam from the K500 cyclotron. With this in-beam data, waveform integration parameters may be optimized. Results from the testing of these detectors with flash digitizers will be presented. Department of Energy, National Science Foundation, Cyclotron Institute.

  17. Synthesis of barium titanate crystalline nanoparticles using hydrothermal microwave method

    International Nuclear Information System (INIS)

    Souza, A.E.; Silva, R.A.; Teixeira, S.R.; Moreira, M.L.; Volanti, D.P.; Longo, E.

    2009-01-01

    The hydrothermal microwave method (HTMW) was used in the synthesis of barium titanate (BaTiO 3 ) nanoparticles. The solution was prepared in deionized water by using titanium (IV) isopropoxide (C 12 H 28 O 4 Ti), barium chloride (BaCl 2 .2H 2 O) and potassium hydroxide (KOH). Afterwards it was heated in an adapted conventional microwave oven. The system is composed of a temperature controller with thermocouple, a hermetic camera of reaction made of teflon, a manometer and a safety valve. The solution was heated to 140 deg C, at a 140 deg C/min heating rate, and maintained at this temperature for 40 minutes. The obtained ceramic powder was characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD data confirms the formation of a high crystalline ceramic material with perovskite structure. The FE-SEM images reveal morphologies with dimensions varying from 27 to 54 nm. (author)

  18. Green Synthesis of Barium Sulfate Particles Using Plant Extracts

    Directory of Open Access Journals (Sweden)

    Chen Long

    2016-01-01

    Full Text Available The biological molecules in the extracts of four fruits or vegetables: kiwifruit, oranges, tomato and carrot, were used as templates to synthesize barium sulfate (BaSO4 particles. The products were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray power diffractometry. The results showed that, leaf-shaped barite BaSO4 crystals with toothed edge were obtained with kiwifruit extracts; thorn spherical barium sulfate crystals with diameter of 2-4 micrometers were produced with tomato extracts; rod-like or quasi-spherical BaSO4 crystals with size of several hundred nanometers to several micrometers were gained with orange extracts; while quasi-spherical BaSO4 nano-crystals were obtained with carrot extracts. The formation mechanism of BaSO4 is also discussed, showing that the proteins, carbohydrates, vitamins and organic acids in above four kinds of fruits or vegetables may provide nucleation sites, controlling the growth of BaSO4 crystals with different morphologies.

  19. Study of barium bismuth titanate prepared by mechanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Lazarević Z.Ž.

    2009-01-01

    Full Text Available Barium-bismuth titanate, BaBi4Ti4O15 (BBT, a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.

  20. Hydride reorientation in Zircaloy-4 examined by in situ synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Weekes, H.E. [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom); Jones, N.G. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Lindley, T.C. [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom); Dye, D., E-mail: david.dye@imperial.ac.uk [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom)

    2016-09-15

    The phenomenon of stress-reorientation has been investigated using in situ X-ray diffraction during the thermomechanical cycling of hydrided Zircaloy-4 tensile specimens. Results have shown that loading along a sample’s transverse direction (TD) leads to a greater degree of hydride reorientation when compared to rolling direction (RD)-aligned samples. The elastic lattice micro-strains associated with radially oriented hydrides have been revealed to be greater than those oriented circumferentially, a consequence of strain accommodation. Evidence of hydride redistribution after cycling, to α-Zr grains oriented in a more favourable orientation when under an applied stress, has also been observed and its behaviour has been found to be highly dependent on the loading axis. Finally, thermomechanical loading across multiple cycles has been shown to reduce the difference in terminal solid solubility of hydrogen during dissolution (TSS{sub D,H}) and precipitation (TSS{sub P,H}).

  1. Hydride Transfer in DHFR by Transition Path Sampling, Kinetic Isotope Effects, and Heavy Enzyme Studies

    Science.gov (United States)

    Wang, Zhen; Antoniou, Dimitri; Schwartz, Steven D.; Schramm, Vern L.

    2016-01-01

    Escherichia coli dihydrofolate reductase (ecDHFR) is used to study fundamental principles of enzyme catalysis. It remains controversial whether fast protein motions are coupled to the hydride transfer catalyzed by ecDHFR. Previous studies with heavy ecDHFR proteins labeled with 13C, 15N, and nonexchangeable 2H reported enzyme mass-dependent hydride transfer kinetics for ecDHFR. Here, we report refined experimental and computational studies to establish that hydride transfer is independent of protein mass. Instead, we found the rate constant for substrate dissociation to be faster for heavy DHFR. Previously reported kinetic differences between light and heavy DHFRs likely arise from kinetic steps other than the chemical step. This study confirms that fast (femtosecond to picosecond) protein motions in ecDHFR are not coupled to hydride transfer and provides an integrative computational and experimental approach to resolve fast dynamics coupled to chemical steps in enzyme catalysis. PMID:26652185

  2. Kinetics of hydrogen evolution from hydrides based on titanium and zirconium

    International Nuclear Information System (INIS)

    Solovetskij, Yu.I.; Chernavskij, P.A.; Lunin, V.V.

    1982-01-01

    Hydrogen evolution from intermetallide hydrides of the composition Zr-Me-H (Me=Co, Fe, Ni) has been studied. Hydrogen evolution from hydrides ZrHsub(1.98) and ZrCoHsub(2.88) is accompanied by phase transitions. On the basis of kinetics (the range 570-680 K) of hydrogen evolution for the systems ZrCosub(2)Hsub(0.20), ZrFeHsub(0.52) and ZrNiHsub(2.88) a conclusion is made on the constant character of their phase composition. For the hydrides mentioned as well as for TiHsub(1.93) kinetic dependences are presented. It is pointed out that the composition of surface and time of hydride storage make a considerable effect on kinetics of hydrogen evolution

  3. Unexpected formation of hydrides in heavy rare earth containing magnesium alloys

    Directory of Open Access Journals (Sweden)

    Yuanding Huang

    2016-09-01

    Full Text Available Mg–RE (Dy, Gd, Y alloys show promising for being developed as biodegradable medical applications. It is found that the hydride REH2 could be formed on the surface of samples during their preparations with water cleaning. The amount of formed hydrides in Mg–RE alloys is affected by the content of RE and heat treatments. It increases with the increment of RE content. On the surface of the alloy with T4 treatment the amount of formed hydride REH2 is higher. In contrast, the amount of REH2 is lower on the surfaces of as-cast and T6-treated alloys. Their formation mechanism is attributed to the surface reaction of Mg–RE alloys with water. The part of RE in solid solution in Mg matrix plays an important role in influencing the formation of hydrides.

  4. In situ probing of surface hydrides on hydrogenated amorphous silicon using attenuated total reflection infrared spectroscopy

    CERN Document Server

    Kessels, W M M; Sanden, M C M; Aydil, E S

    2002-01-01

    An in situ method based on attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) is presented for detecting surface silicon hydrides on plasma deposited hydrogenated amorphous silicon (a-Si:H) films and for determining their surface concentrations. Surface silicon hydrides are desorbed by exposing the a-Si:H films to low energy ions from a low density Ar plasma and by comparing the infrared spectrum before and after this low energy ion bombardment, the absorptions by surface hydrides can sensitively be separated from absorptions by bulk hydrides incorporated into the film. An experimental comparison with other methods that utilize isotope exchange of the surface hydrogen with deuterium showed good agreement and the advantages and disadvantages of the different methods are discussed. Furthermore, the determination of the composition of the surface hydrogen bondings on the basis of the literature data on hydrogenated crystalline silicon surfaces is presented, and quantification of the h...

  5. The uranium zirconium hydride research reactor and its applications in research and education

    Energy Technology Data Exchange (ETDEWEB)

    Chen Wei; Wang Daohua; Jiang Xinbiao; A Jinyan; Yang Jun; Chen Da [Northwest Institute of Nuclear Technology, Xi' an (China)

    2003-03-01

    This paper describes briefly the performance, the configuration and the prospects of extensive applications in science, technology and education of the Uranium Zirconium Hydride research reactor in China. (author)

  6. Corrosion behavior of Zircaloy 4 cladding material. Evaluation of the hydriding effect

    Energy Technology Data Exchange (ETDEWEB)

    Blat, M. [Electricite de France, 77 - Moret sur Loing (France). Dept. Etudes des Materiaux Les Renardieres; Bourgoin, J. [Electricite de France, 37 - Avoine (France)

    1997-04-01

    In this work, particular attention has been paid to the hydriding effect in PIE and laboratory test to validate a detrimental hydrogen contribution on Zircaloy 4 corrosion behavior at high burnup. Laboratory corrosion tests results confirm that hydrides have a detrimental role on corrosion kinetics. This effect is particularly significant for cathodic charged samples with a massive hydride outer layer before corrosion test. PIE show that at high burnup a hydride layer is formed underneath the metal/oxide interface. The results of the metallurgical examinations are discussed with respect to the possible mechanisms involved in this detrimental effect of hydrogen. Therefore, according to the laboratory tests results and PIE, hydrogen could be a strong contributor to explain the increase in corrosion rate at high burnup. (author) 12 refs.

  7. Delayed hydride cracking in Zr-2.5Nb pressure tubes

    International Nuclear Information System (INIS)

    Mieza, Juan I.; Domizzi, Gladys; Vigna, Gustavo L.

    2007-01-01

    Zr-2.5 Nb alloy from CANDU pressure tubes are prone to failure by hydrogen intake. One of the degradation mechanisms is delayed hydride cracking, which is characterized by the velocity of cracking. In this work, we study the effect of beta zirconium phase transformation over delayed hydride cracking velocity in Zr-2.5 Nb alloy from pressure tubes. Acoustic emission technique was used for cracking detection. (author) [es

  8. Current Compensation of Hydrogen Ion Beam Extracted from PIG with Metal-Hydride Cathode

    International Nuclear Information System (INIS)

    Borisko, V.N.; Sereda, I.N.; Klochko, E.V.; Tseluyko, A.F.; Afanas'eva, I.A.

    2006-01-01

    The effect of extracted hydrogen ion beam compensation from reflective discharge with metal-hydride cathode that sufficiently widens the possible field of applying plasma sources of such type is found. The evolution of energy distribution function of ions extracted along the axial direction from reflective discharge with metal-hydride cathode depending on external parameters of the discharge is investigated. The electron distribution functions which compensate hydrogen ion beam are determined

  9. Standardized hydrogen storage module with high utilization factor based on metal hydride-graphite composites

    OpenAIRE

    Bürger, Inga; Dieterich, Mila; Pohlmann, Carsten; Röntzsch, Lars; Linder, Marc

    2017-01-01

    In view of hydrogen based backup power systems or small-scale power2gas units, hydrogen storages based on metal hydrides offer a safe and reliable solution. By using Hydralloy C5 as suitable hydride forming alloy, the present tank design guarantees very simple operating conditions: pressures between 4 bar and 30 bar, temperatures between 15 C and 40 C and minimal efforts for thermal management in combination with fast and constant charging and discharging capabilities. The modular...

  10. Dehydrogenation in lithium borohydride/conventional metal hydride composite based on a mutual catalysis

    DEFF Research Database (Denmark)

    Yu, X.B.; Shi, Qing; Vegge, Tejs

    2009-01-01

    The dehydrogenation of LiBH4 ball-milled with hydrogenated 40Ti–15Mn–15Cr–30V alloy was investigated. It was found that there is a mutual catalysis between the two hydrides, lowering the temperature of hydrogen release from both hydrides. In the case of 1h milled LiBH4/40Ti–15Mn–15Cr–30V...

  11. An Investigation on the Persistence of Uranium Hydride during Storage of Simulant Nuclear Waste Packages

    OpenAIRE

    Stitt , C. A.; Harker , N. J.; Hallam , K. R.; Paraskevoulakos , C.; Banos , A.; Rennie , S.; Jowsey , J.; Scott , T. B.

    2015-01-01

    International audience; Synchrotron X-rays have been used to study the oxidation of uranium and uranium hydride when encapsulated in grout and stored in de-ionised water for 10 months. Periodic synchrotron X-ray tomography and X-ray powder diffraction have allowed measurement and identification of the arising corrosion products and the rates of corrosion. The oxidation rates of the uranium metal and uranium hydride were slower than empirically derived rates previously reported for each reacta...

  12. Trapping of antimony and bismuth hydrides on a molybdenum-foil strip

    Czech Academy of Sciences Publication Activity Database

    Krejčí, Pavel; Dočekal, Bohumil

    2005-01-01

    Roč. 99, S (2005), s148-s149 ISSN 0009-2770. [Meeting on Chemistry and Life /3./. Brno, 20.09.2005-22.09.2005] R&D Projects: GA AV ČR IAA400310507 Institutional research plan: CEZ:AV0Z40310501 Keywords : hydride generation * hydride trapping * molybdenum-foil strip device Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.445, year: 2005

  13. A NOVEL METHOD OF THE HYDRIDE SEPARATION FOR THE DETERMINATION OF ARSENIC AND ANTIMONY BY AAS

    Directory of Open Access Journals (Sweden)

    Ganden Supriyanto

    2010-06-01

    Full Text Available A novel method is proposed for the hydride separation when determinining of arsenic and antimony by AAS. A chromatomembrane cell was used as preconcentration-, extraction- and separation-manifold instead of the U-tube phase separator, which is normally fitted in continuous flow vapour systems generating conventionaly the hydrides. The absorbances of the hydrides produced were measured by an atomic absorption spectrophotometer at 193.7 nm and 217.6 nm. Under optimized analytical conditions, the calibration plot for arsenic was linear from 50 to 500 ng.mL-1 (r2 = 0.9982. The precision for three subsequent measurements of 500 ng.mL-1 arsenic gave rise to a relative standard deviation of 0.4%. The detection limit was 15 ng.mL-1, which is much lower compared with that of the conventional hydride system (2000 ng.mL-1. A similar result was observed in case of antimony: the detection limit was 8 ng.mL-1 when the proposed method was applied. Consequently, the sensitivity of the novel method surpasses systems with conventional hydride generation, i.e. the precision and the acuracy increase whereas the standard deviation and the detection limit decrease. The proposed method was applied in pharmacheutial analysis and the certified As-content of a commercial product was very sufficiently confirmed.   Keywords: Chromatomembrane Cell, Hydride separation, Arsenic detection, Antimony detection, AAS

  14. Synthesis, spectroscopy, and hydrogen/deuterium exchange in high-spin iron(II) hydride complexes.

    Science.gov (United States)

    Dugan, Thomas R; Bill, Eckhard; MacLeod, K Cory; Brennessel, William W; Holland, Patrick L

    2014-03-03

    Very few hydride complexes are known in which the metals have a high-spin electronic configuration. We describe the characterization of several high-spin iron(II) hydride/deuteride isotopologues and their exchange reactions with one another and with H2/D2. Though the hydride/deuteride signal is not observable in NMR spectra, the choice of isotope has an influence on the chemical shifts of distant protons in the dimers through the paramagnetic isotope effect on chemical shift. This provides the first way to monitor the exchange of H and D in the bridging positions of these hydride complexes. The rate of exchange depends on the size of the supporting ligand, and this is consistent with the idea that H2/D2 exchange into the hydrides occurs through the dimeric complexes rather than through a transient monomer. The understanding of H/D exchange mechanisms in these high-spin iron hydride complexes may be relevant to postulated nitrogenase mechanisms.

  15. Investigation of the effect of hydride and iodine on the mechanical behaviour of the zircaloy-4

    International Nuclear Information System (INIS)

    Soares, M.I.

    1981-12-01

    To investigate the effect of hydride and iodine on the mechanical behaviour of the zircaloy-4 tubes, deformation tests under pressure of samples hydrided in autoclave and of samples containing iodine were carried out, in order to simulate the fission product. The same tests were carried out in samples without hydride and iodine contents that were used as reference samples in the temperature range of 650 0 C-950 0 C. The hydrided samples and the samples containing iodine tested at 650 0 C and 750 0 C showed a higher ductility than the samples of reference. The hydrided samples tested at 850 0 C and 950 0 C showed a higher embritlement than the samples of reference and than the samples containing iodine tested at the same temperatures. A mechanical test has been developed to investigate the effect of hydride and iodine on the mechanical behaviour of the zircaloy-4 tubes. The mechanical test were carried out at room temperature. At room temperature the hydrition decreased the ductility of zircaloy-4. At room temperature the sample containing iodine showed a higher ductility than the sample without iodine. The combined action of hydrogen and iodine at room temperature enhanced the embrittlment of the samples zircaloy-4. (Author) [pt

  16. Hydrogen charging, hydrogen content analysis and metallographic examination of hydride in zirconium alloys

    International Nuclear Information System (INIS)

    Singh, R.N.; Kishore, R.; Mukherjee, S.; Roychowdhury, S.; Srivastava, D.; Sinha, T.K.; De, P.K.; Banerjee, S.; Gopalan, B.; Kameswaran, R.; Sheelvantra, Smita S.

    2003-12-01

    Gaseous and electrolytic hydrogen charging techniques for introducing controlled amount of hydrogen in zirconium alloy is described. Zr-1wt%Nb fuel tube, zircaloy-2 pressure tube and Zr-2.5Nb pressure tube samples were charged with up to 1000 ppm of hydrogen by weight using one of the aforementioned methods. These hydrogen charged Zr-alloy samples were analyzed for estimating the total hydrogen content using inert gas fusion technique. Influence of sample surface preparation on the estimated hydrogen content is also discussed. In zirconium alloys, hydrogen in excess of the terminal solid solubility precipitates out as brittle hydride phase, which acquire platelet shaped morphology due to its accommodation in the matrix and can make the host matrix brittle. The F N number, which represents susceptibility of Zr-alloy tubes to hydride embrittlement was measured from the metallographs. The volume fraction of the hydride phase, platelet size, distribution, interplatelet spacing and orientation were examined metallographically using samples sliced along the radial-axial and radial-circumferential plane of the tubes. It was observed that hydride platelet length increases with increase in hydrogen content. Considering the metallographs generated by Materials Science Division as standard, metallographs prepared by the IAEA round robin participants for different hydrogen concentration was compared. It is felt that hydride micrographs can be used to estimate not only that approximate hydrogen concentration of the sample but also its size, distribution and orientation which significantly affect the susceptibility to hydride embrittlement of these alloys. (author)

  17. Effects of Hydride Rim on Ductility of Zircaloy-4 using Ring Compression Test

    Energy Technology Data Exchange (ETDEWEB)

    Kang, So-Young; Kim, Ho-A; Lee, Ji-Min; Kim, Yong-Soo [Hanyang University, Seoul (Korea, Republic of)

    2016-10-15

    The objective of this preliminary study is to form hydride rim around the cladding outside wall typically observed for high burnup fuel cladding. In addition, ring compression test (RCT) that simulates pinch-type loading subjected to cladding during SNF transportation is conducted to investigate separate effects of hydride rim on mechanical properties of the cladding. In this preliminary study, in order to simulate high burnup fuel cladding, hydride rim was attempted to form around the cladding outside wall. Encapsulated 150 mm long Zircaloy-4 tube which was plated with nickel at outer surface was used and then it charged with hydrogen using gaseous hydrogenation method. Finally, hydride rim whose thickness is 0-95 μm at outer cladding surface was successively formed. On the other hand, ring compression tests which simulate pinch-type loading were conducted to investigate the mechanical property degradation depending on the hydride rim thickness. The results showed that as the thickness increases, the specimen ruptured earlier and fracture strain decreases. These results demonstrate that the hydride rim deteriorates the ductility of zirconium alloy cladding.

  18. Influence of Milling Conditions on the Hydriding Properties of Mg-C Nanocomposites

    Directory of Open Access Journals (Sweden)

    Hristina Stoyadinova

    2015-01-01

    Full Text Available Mg75 at.%, CB25 at.% (CB: carbon black composites were synthesized at different ball milling conditions (milling energy, milling duration, and environment and their hydriding properties were characterized by high-pressure DSC. The SEM observations revealed that the samples consist of 5–15 μm Mg particles, surrounded and in some cases coated by carbon particles. X-ray diffraction analysis showed that the Mg phase of all as-obtained composite powders is nanocrystalline with average crystallite size in the range 20–30 nm, depending on the milling conditions. The best hydriding properties, expressed in low-temperature hydriding (below 150°C and improved cycle life, showed the composites milled at dry conditions. This is obviously due mainly to the successful Mg surface protection by the carbon. Additional decrease of the hydriding temperature (<100°C was achieved applying higher-energy milling, but at the same time the cycling stability deteriorated, due to the extremely fine particles and microstructure achieved under these conditions. The composites milled in the presence of heptane showed rapid capacity decline during cycling as well. The observed difference in the hydriding behavior of the Mg-CB composites is attributed to the different coating efficiency of the carbon milled under different conditions with Mg, which is supposed to protect magnesium from oxidation and plays a catalytic role for the hydriding reaction.

  19. AB{sub 2} metal hydrides for high-pressure and narrow temperature interval applications

    Energy Technology Data Exchange (ETDEWEB)

    Hagstroem, M.T.; Vanhanen, J.P.; Lund, P.D. [Helsinki Univ. of Technol., Hut (Finland). Dept. of Eng. Phys. and Math.

    1998-05-01

    AB{sub 2}-based metal hydrides have been studied in order to find high-capacity, low-hysteresis alloy-hydrogen systems for high-pressure applications with strict thermal boundary conditions. TiCrMn{sub 1-3x}Fe{sub 2x}V{sub x} (x=0, 0.05, 0.1, 0.15 or 0.2) and Ti{sub 1-y}Zr{sub y}(Cr{sub z}Mn{sub 1-z}){sub 2} (y=0.05 or 0.15 and z=0.5 or 0.6) alloys have been synthesized and characterised by XRD, ICP spectrometry and volumetric PCI measurements. In addition, the PCIs of two commercial (GfE) alloys, Hydralloy C2 and Hydralloy C0, have been measured and a PDSC study on Hydralloy C2 has been performed, in order to assess the feasibility of their basic hydriding properties for narrow temperature interval applications. In the Fe and V containing alloy-hydrogen systems, hysteresis can be overcome at the cost of reduced hydriding capacity, while in the Zr-containing hydrides, at the temperatures of this study (-80 to 60 C), hysteresis is not completely eliminated but the hydriding capacity remains good also at high temperatures. The interplay between these properties of hydrides is discussed, as well as the role of materials characteristics in specially constrained applications. (orig.) 17 refs.

  20. Morphology study on the depleted uranium as hydriding/dehydriding cycles

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Dong-you, E-mail: dongyou@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Yun, Sei-Hun; Kang, Hyun-Goo; Chang, Min Ho; Oh, Yun Hee [National Fusion Research Institute, Daejeon (Korea, Republic of); Kang, Kweon Ho; Woo, Yoon Myung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    Depleted Uranium (DU) is one of the strongest candidates as a getter material of hydrogen isotopes in the nuclear fusion reactor. In this work, small DU lump specimen with 99.8% purity was prepared for observation of morphology variation as hydriding/dehydriding cycles. Hydriding/dehydriding of DU was carried out more than 10 cycles for powder preparation. The pulverized DU specimen was safely handled in the glove box under Argon gas condition to minimize contact with oxygen and humidity. The morphology change according to hydriding/dehydriding cycles was observed by visual cell reactor, optical microscope and scanning electron microscope. The first hydriding of the small DU sample has progressed slowly with surface enlargement and volume expansion as time passes. After third hydriding/dehydriding cycles, most of DU was pulverized. The powder fineness of DU developed as hydriding/dehydriding cycle progresses. But the agglomerates of fine DU particles were observed. It was confirmed that the DU particles exist as porous agglomerates. And the particle agglomerate shows poor fluidity and even has the cohesive force.

  1. First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

    2013-09-01

    Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density-functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption into interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest-energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.

  2. Experimental study of a metal hydride driven braided artificial pneumatic muscle

    Science.gov (United States)

    Vanderhoff, Alexandra; Kim, Kwang J.

    2009-12-01

    This paper reports the experimental study of a new actuation system that couples a braided artificial pneumatic muscle (BAPM) with a metal hydride driven hydrogen compressor to create a compact, lightweight, noiseless system capable of high forces and smooth actuation. The results indicate that the metal hydride-BAPM system has relatively good second law efficiency average of 30% over the desorption cycle. The thermal efficiency is low, due mainly to the highly endothermic chemical reaction that releases the stored hydrogen gas from the metal hydride. The force to metal hydride weight is very high (~14 000 NForce/kgMH) considering that this system has not been optimized to use the minimum amount of metal hydride required for a full actuation stroke of the fluidic muscle. Also, a thermodynamic model for the complete system is developed. The analysis is restricted in some aspects concerning the complexity of the hydriding/dehydriding chemical process of the system and the three-dimensional geometry of the reactor, but it provides a useful comparison to other actuation devices and clearly reveals the parameters necessary for optimization of the actuation system in future work. The system shows comparable work output and has the benefits of biological muscle-like properties for potential use in robotic systems.

  3. Fabrication and characterization of cerium-doped barium titanate inverse opal by sol-gel method

    International Nuclear Information System (INIS)

    Jin Yi; Zhu Yihua; Yang Xiaoling; Li Chunzhong; Zhou Jinghong

    2007-01-01

    Cerium-doped barium titanate inverted opal was synthesized from barium acetate contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a polystyrene (PS) opal. This procedure involves infiltration of precursors into the interstices of the PS opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the PS opal by calcination. The morphologies of opal and inverse opal were characterized by scanning electron microscope (SEM). The pores were characterized by mercury intrusion porosimetry (MIP). X-ray photoelectron spectroscopy (XPS) investigation showed the doping structure of cerium, barium and titanium. And powder X-ray diffraction allows one to observe the influence of doping degree on the grain size. The lattice parameters, crystal size and lattice strain were calculated by the Rietveld refinement method. The synthesis of cerium-doped barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three-dimensional photonic crystal devices. - Graphical abstract: Cerium-doped barium titanate inverted opal was synthesized from barium acetate acid contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a PS opal, which involves infiltration of precursors into the interstices of the PS opal template and removal of the PS opal by calcination

  4. Trapping of hydride forming elements within miniature electrothermal devices: part 1. Investigation of collection of arsenic and selenium hydrides on a molybdenum foil strip

    Czech Academy of Sciences Publication Activity Database

    Dočekal, Bohumil; Gucer, S.; Selecká, Anna

    2004-01-01

    Roč. 59, č. 4 (2004), s. 487-495 ISSN 0584-8547. [CSI. Presymposium on Sample Introduction in Atomic Spectrometry /33./. Zaragoza, 03.09.2003-06.09.2003] R&D Project s: GA ČR GA203/01/0453 Grant - others:Scientific and Technical Research Council of Turkey (TUBITAK)(TR) NATO-PC B Advanced Fellowship- Project No. 304 Institutional research plan: CEZ:AV0Z4031919 Keywords : Arsenic hydride generation * Selenium hydride generation * Molybdenum foil trap Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.086, year: 2004

  5. Hydrogen generation using silicon nanoparticles and their mixtures with alkali metal hydrides

    Science.gov (United States)

    Patki, Gauri Dilip

    mole of Si. We compare our silicon nanoparticles (˜10nm diameter) with commercial silicon nanopowder (<100nm diameter) and ball-milled silicon powder (325 mesh). The increase in rate upon decreasing the particle size to 10 nm was even greater than would be expected based upon the increase in surface area. While specific surface area increased by a factor of 6 in going from <100 nm to ˜10 nm particles, the hydrogen production rate increased by a factor of 150. However, in all cases, silicon requires a base (e.g. NaOH, KOH, hydrazine) to catalyze its reaction with water. Metal hydrides are also promising hydrogen storage materials. The optimum metal hydride would possess high hydrogen storage density at moderate temperature and pressure, release hydrogen safely and controllably, and be stable in air. Alkali metal hydrides have high hydrogen storage density, but exhibit high uncontrollable reactivity with water. In an attempt to control this explosive nature while maintaining high storage capacity, we mixed our silicon nanoparticles with the hydrides. This has dual benefits: (1) the hydride- water reaction produces the alkali hydroxide needed for base-catalyzed silicon oxidation, and (2) dilution with 10nm coating by, the silicon may temper the reactivity of the hydride, making the process more controllable. Initially, we analyzed hydrolysis of pure alkali metal hydrides and alkaline earth metal hydrides. Lithium hydride has particularly high hydrogen gravimetric density, along with faster reaction kinetics than sodium hydride or magnesium hydride. On analysis of hydrogen production we found higher hydrogen yield from the silicon nanoparticle—metal hydride mixture than from pure hydride hydrolysis. The silicon-hydride mixtures using our 10nm silicon nanoparticles produced high hydrogen yield, exceeding the theoretical yield. Some evidence of slowing of the hydride reaction rate upon addition of silicon nanoparticles was observed.

  6. Effects of outgassing of loader chamber walls on hydriding of thin films for commercial applications

    Energy Technology Data Exchange (ETDEWEB)

    Provo, James L., E-mail: jlprovo@verizon.net [Consultant, J.L. Provo Consulting, Trinity, Florida 34655-7179 (United States)

    2014-07-01

    An important aspect of understanding industrial processing is to know the characteristics of the materials used in such processes. A study was performed to determine the effects of hydriding chamber material on the degree of hydriding for the commercial production of thin film hydride targets for various research universities, commercial companies, and government national laboratories. The goal was to increase the degree of hydriding of various thin film hydrides and to study the vacuum environment during air-exposure hydriding. For this purpose, dynamic residual gas analysis during deuterium gas hydride processing was utilized with erbium thin films, employing a special set-up for direct dynamic hydride gas sampling during processing at elevated temperature and full loading gas pressure. Complete process data for (1) a copper–(1.83 wt. %)beryllium wet hydrogen fired passivated (600 °C–1 h) externally heated pipe hydriding chamber are reported. Dynamic residual gas analysis comparisons during hydriding are presented for hydriding chambers made from (2) alumina (99.8 wt. %), (3) copper (with an interior aluminum coating ∼10 k Å thick, and (4) for a stainless-steel air-fired passivated (900 °C–1 h) chamber. Dynamic data with deuterium gas in the chamber at the hydriding temperature (450 °C) showed the presence and growth of water vapor (D{sub 2}O) and related mixed ion species(H{sub 2}O{sup +}, HDO{sup +}, D{sub 2}O{sup +}, and OD{sup +}) from hydrogen isotope exchange reactions during the 1 h process time. Peaks at mass-to-charge ratios (i.e., m/e) of 12(C{sup +}), 16(CD{sub 2}{sup +}), 17(CHD{sub 2}{sup +}), and 18(CD{sub 3}{sup +}, OD{sup +}) increased for approximately the first half hour of a 1 h hydriding process and then approach steady state. Mass-to-charge peaks at 19(HDO{sup +}) and 20(D{sub 2}O{sup +}) continue to increase throughout the process cycle. Using the m/e = 20 (D{sub 2}O{sup +}) peak intensity from chamber (1

  7. Reaction Kinetics with Hydrogen and Temperature Dependence of the Hydriding Rate for a Magnesium-Based Nickel Iron Oxide Alloy

    International Nuclear Information System (INIS)

    Song, Myoung Youp; Baek, Sung Hwan; Park, Hye Ryoung

    2012-01-01

    A 71.5 wt%Mg-23.5 wt%Ni-5 wt%Fe 2 O 3 (Mg-23.5Ni-5Fe 2 O 3 ) sample was prepared by a quite simple process, reactive mechanical grinding, and its hydriding and dehydriding properties were then investigated. The reactive mechanical grinding of Mg with Ni and Fe 2 O 3 is considered to facilitate nucleation and shorten the diffusion distances of the hydrogen atoms. After the hydriding-dehydriding cycling, the Mg-23.5Ni-5Fe 2 O 3 sample contained Mg 2 Ni phase. Expansion and contraction of the hydride-forming materials (Mg and Mg 2 Ni) with the hydriding and dehydriding reactions are also considered to increase the hydriding and dehydriding rates of the mixture by forming defects and cracks leading to the fragmentation of the particles. The temperature dependence of the hydriding rate of the sample is discussed.

  8. Wideband and enhanced microwave absorption performance of doped barium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Pingyuan; Xiong, Kun [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Ju, Kui [Guizhou Institute of Metallurgy and Chemical Engineering, Guiyang 550002 (China); Li, Shengnan [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Xu, Guangliang, E-mail: xuguangliang@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2015-07-01

    To achieve stronger microwave attenuation and larger bandwidth in electromagnetic absorber, the nickel ions (Ni{sup 2+}) and manganese ions (Mn{sup 2+}) were employed to partially replace the cobalt ions (Co{sup 2+}) in BaCoTiFe{sub 10}O{sub 19}, and the doped barium hexaferrite (Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19} and Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19}) powders were synthesized via the sol–gel combustion method. Subsequently, the microwave absorbing composites were prepared by mixing the ferrite powders with the paraffin. The X-ray diffraction (XRD) patterns of the doped ferrites confirmed the formation of the M-type barium ferrite, and no other types of barium ferrite could be found. Based on the electromagnetic parameters measured by the vector net-analyzer, it was found that the composite (Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19}) possessed a minimum reflection loss of −52.8 dB at 13.4 GHz with a matching thickness of 1.8 mm and the bandwidth below −15 dB was 5.8 GHz. Moreover, the maximum attenuation of Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19} could reach −69 dB when its thickness was 1.8 mm, and also the bandwidth less than −20 dB was ranging from 13.2 GHz to 18 GHz. Thus, Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19} and Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19} could be the good microwave absorbers, which have great potentials to be applied in the high frequency fields of the microwave absorbing materials. - Highlights: • The Co was first time substituted by Mn–Ni in ferrites. • The substituted ferrites had good microwave absorption. • The doped ferrites had broad bandwidth and low reflection loss.

  9. Microstructure of doped barium titanate prepared from polymeric precursors

    Directory of Open Access Journals (Sweden)

    Stojanovic, B. D.

    2002-02-01

    Full Text Available Barium titanate is used extensively as a dielectric in ceramic capacitors, particularly due to its high dielectric constant and low dielectric loss characteristics. It can be made semiconducting by addition of certain dopants and by proper modification of grains and grain boundary properties obtaining very interesting characteristics for various applications. The synthesis method and sintering regime have a strong influence on properties of obtained barium titanate ceramics. Doped barium titanate was prepared with Nb+5 and Y+3 ions as donor dopants, and with Mn+2 ions as acceptor dopant by polymeric precursors method. By this procedure nanosized powders were obtained after calcination. Sintering was performed in the temperature range of 1290ºC to 1380ºC. The microstructure of doped BaTiO3 was performed using scanning electron microscopy. The influence of dopants and sintering temperature on grain size was analysed.

    El titanato de bario se usa extensamente como dieléctrico en condensadores cerámicos, debido principalmente a su elevada constante dieléctrica y a sus bajas pérdidas dieléctricas. Puede hacerse semiconductor mediante la adición de ciertos dopantes y a través de modificaciones adecuadas de las propiedades de los granos y los bordes de grano se obtienen características muy interesantes para muchas aplicaciones. El método de síntesis y el régimen de sinterización tienen una fuerte influencia sobre las propiedades del titanato de bario cerámico. El titanato de bario dopado con Nb5+ y Y3+ como dopantes donores y con Mn2+ como dopante aceptor se preparó mediante el método de precursores poliméricos. Mediante este procedimiento se obtuvieron polvos nanométricos después de la etapa de calcinación. La sinterización se realizó en el intervalo de temperaturas entre 1290ºC y 1380ºC. La microestructura del BaTiO3 dopado se estudió usando microscopía electrónica de barrido. Se analizó la influencia de los

  10. Complex Hydride Compounds with Enhanced Hydrogen Storage Capacity

    Energy Technology Data Exchange (ETDEWEB)

    Mosher, Daniel A.; Opalka, Susanne M.; Tang, Xia; Laube, Bruce L.; Brown, Ronald J.; Vanderspurt, Thomas H.; Arsenault, Sarah; Wu, Robert; Strickler, Jamie; Anton, Donald L.; Zidan, Ragaiy; Berseth, Polly

    2008-02-18

    The United Technologies Research Center (UTRC), in collaboration with major partners Albemarle Corporation (Albemarle) and the Savannah River National Laboratory (SRNL), conducted research to discover new hydride materials for the storage of hydrogen having on-board reversibility and a target gravimetric capacity of ≥ 7.5 weight percent (wt %). When integrated into a system with a reasonable efficiency of 60% (mass of hydride / total mass), this target material would produce a system gravimetric capacity of ≥ 4.5 wt %, consistent with the DOE 2007 target. The approach established for the project combined first principles modeling (FPM - UTRC) with multiple synthesis methods: Solid State Processing (SSP - UTRC), Solution Based Processing (SBP - Albemarle) and Molten State Processing (MSP - SRNL). In the search for novel compounds, each of these methods has advantages and disadvantages; by combining them, the potential for success was increased. During the project, UTRC refined its FPM framework which includes ground state (0 Kelvin) structural determinations, elevated temperature thermodynamic predictions and thermodynamic / phase diagram calculations. This modeling was used both to precede synthesis in a virtual search for new compounds and after initial synthesis to examine reaction details and options for modifications including co-reactant additions. The SSP synthesis method involved high energy ball milling which was simple, efficient for small batches and has proven effective for other storage material compositions. The SBP method produced very homogeneous chemical reactions, some of which cannot be performed via solid state routes, and would be the preferred approach for large scale production. The MSP technique is similar to the SSP method, but involves higher temperature and hydrogen pressure conditions to achieve greater species mobility. During the initial phases of the project, the focus was on higher order alanate complexes in the phase space

  11. In vitro experiments for the development of a high density (HD) barium sulfate contrast medium

    International Nuclear Information System (INIS)

    Klein, J.

    1986-01-01

    In vitro experiments with the high-density (HD) barium meal Falibaryt HD are described. Several charges of BaSO 4 were tested together with certain additives influencing dispersion, stability of the suspension, flowability, surface tension etc. Particle size spectra were measured by the manufacturer, VEB Fahlberg-List. With a simple PVC test plate containing several grooves simulating small details (areae gastricae) the diagnostic capabilities of the HD contrast medium were evaluated in an in vitro test. The developed barium meal Falibaryt HD is in its physical and chemical parameters comparable with Prontobario-HD, one of the best HD barium meals. (author)

  12. Addition of methyl cellulose enema to double-contrast barium imaging of sigmoid diverticulosis

    International Nuclear Information System (INIS)

    Olsson, R.; Adnerhill, I.; Bjoerkdahl, P.; Ekberg, O.; Fork, F.T.

    1997-01-01

    Double-contrast barium enema has a reduced sensitivity in patients with severe sigmoid diverticulosis. Therefore a carboxy methyl cellulose enema was employed after the conventional double-contrast examination in 15 patients with sigmoid diverticulosis. A significant increase in lumen diameter and a superior removal of barium residue from the diverticulas facilitated the interpretation of the sigmoid loops. Conclusion: The addition of methyl cellulose enema to double-contrast barium imaging improves diagnostic imaging in diverticulosis by expanding the lumen and emptying the diverticulas. (orig.)

  13. Addition of methyl cellulose enema to double-contrast barium imaging of sigmoid diverticulosis

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, R. [Malmoe Univ. Hospital (Sweden). Dept. of Diagnostic Radiology; Adnerhill, I. [Malmoe Univ. Hospital (Sweden). Dept. of Diagnostic Radiology; Bjoerkdahl, P. [Malmoe Univ. Hospital (Sweden). Dept. of Diagnostic Radiology; Ekberg, O. [Malmoe Univ. Hospital (Sweden). Dept. of Diagnostic Radiology; Fork, F.T. [Malmoe Univ. Hospital (Sweden). Dept. of Diagnostic Radiology

    1997-01-01

    Double-contrast barium enema has a reduced sensitivity in patients with severe sigmoid diverticulosis. Therefore a carboxy methyl cellulose enema was employed after the conventional double-contrast examination in 15 patients with sigmoid diverticulosis. A significant increase in lumen diameter and a superior removal of barium residue from the diverticulas facilitated the interpretation of the sigmoid loops. Conclusion: The addition of methyl cellulose enema to double-contrast barium imaging improves diagnostic imaging in diverticulosis by expanding the lumen and emptying the diverticulas. (orig.).

  14. A Comparative Study on Magnetostructural Properties of Barium Hexaferrite Powders Prepared by Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    Zehra Durmus

    2014-01-01

    Full Text Available Nanocrystalline particles of barium hexaferrite were synthesized by a sol-gel combustion route using nitrate-citrate gels prepared from metal nitrates and citric acid solutions with Fe/Ba molar ratio 12. The present paper aims to study the effect of addition of polyethylene glycol (PEG solutions with different molecular weights (MW: 400, 2000, and 10.000 g/mol on magnetostructural properties of barium hexaferrite. The formation of the barium hexaferrite was inspected using X-ray diffraction (XRD analysis, Fourier transform infrared (FT-IR analysis, thermogravimetric (TGA analysis, scanning electron microscopy (SEM analysis and vibrating sample magnetometer (VSM analysis for magnetic measurements.

  15. Photoexcited-carrier transport in barium strontium titanate/strontium titanate heterostructures

    Science.gov (United States)

    Yan, H.; Wang, J. Y.; Zhang, Z. T.; Yang, B.; Chen, C. L.; Jin, K. X.

    2017-09-01

    Photoexcited-carrier transport properties at the surface and the interface of barium strontium titanate/strontium titanate heterostructures are reported. Under a 365 nm light irradiation, the surfaces of barium strontium titanate films exhibit a metal-to-insulator transition, while the interfaces favor the metallic conduction with increasing temperatures. By analyzing, we consider that these results might be attributed to the intrinsic features of strontium titanate and the polarization state of barium strontium titanate films under the irradiation. Our results would contribute to further understanding of the photocarrier effect at the interface and demonstrate great potential applications in optoelectronic devices of all-oxide heterostructures.

  16. Towards laser cooling and trapping of barium monohydride

    Science.gov (United States)

    McNally, Rees; Iwata, Geoffrey; Tarallo, Marco; Zelevinsky, Tanya

    2017-04-01

    We report progress towards the laser cooling of diatomic BaH, demonstrating operation of a cryogenic buffer gas beam source with a brightness of 106 -107 molecules in the trapping region per ablation pulse, the brightest hydride beam to our knowledge. This source has enabled studies of the transitions and properties of BaH relevant to laser cooling, and we show preliminary results towards optical manipulation. Looking forward, plans for chirped molecular slowing on the A Σ excited state, followed by magneto-optical trapping on the B Σ excited state will be presented. Finally, we discuss the feasibility of photo-dissociation of ultracold BaH as a source of dilute ultracold hydrogen suitable for precision spectroscopy, a unique application for the monohydrides.

  17. Metal hydrides: an innovative and challenging conversion reaction anode for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Luc Aymard

    2015-08-01

    Full Text Available The state of the art of conversion reactions of metal hydrides (MH with lithium is presented and discussed in this review with regard to the use of these hydrides as anode materials for lithium-ion batteries. A focus on the gravimetric and volumetric storage capacities for different examples from binary, ternary and complex hydrides is presented, with a comparison between thermodynamic prediction and experimental results. MgH2 constitutes one of the most attractive metal hydrides with a reversible capacity of 1480 mA·h·g−1 at a suitable potential (0.5 V vs Li+/Li0 and the lowest electrode polarization (2, TiH2, complex hydrides Mg2MHx and other Mg-based hydrides. The reversible conversion reaction mechanism of MgH2, which is lithium-controlled, can be extended to others hydrides as: MHx + xLi+ + xe− in equilibrium with M + xLiH. Other reaction paths—involving solid solutions, metastable distorted phases, and phases with low hydrogen content—were recently reported for TiH2 and Mg2FeH6, Mg2CoH5 and Mg2NiH4. The importance of fundamental aspects to overcome technological difficulties is discussed with a focus on conversion reaction limitations in the case of MgH2. The influence of MgH2 particle size, mechanical grinding, hydrogen sorption cycles, grinding with carbon, reactive milling under hydrogen, and metal and catalyst addition to the MgH2/carbon composite on kinetics improvement and reversibility is presented. Drastic technological improvement in order to the enhance conversion process efficiencies is needed for practical applications. The main goals are minimizing the impact of electrode volume variation during lithium extraction and overcoming the poor electronic conductivity of LiH. To use polymer binders to improve the cycle life of the hydride-based electrode and to synthesize nanoscale composite hydride can be helpful to address these drawbacks. The development of high-capacity hydride anodes should be inspired by the emergent

  18. Metal hydrides: an innovative and challenging conversion reaction anode for lithium-ion batteries.

    Science.gov (United States)

    Aymard, Luc; Oumellal, Yassine; Bonnet, Jean-Pierre

    2015-01-01

    The state of the art of conversion reactions of metal hydrides (MH) with lithium is presented and discussed in this review with regard to the use of these hydrides as anode materials for lithium-ion batteries. A focus on the gravimetric and volumetric storage capacities for different examples from binary, ternary and complex hydrides is presented, with a comparison between thermodynamic prediction and experimental results. MgH2 constitutes one of the most attractive metal hydrides with a reversible capacity of 1480 mA·h·g(-1) at a suitable potential (0.5 V vs Li(+)/Li(0)) and the lowest electrode polarization (lithium are subsequently detailed for MgH2, TiH2, complex hydrides Mg2MH x and other Mg-based hydrides. The reversible conversion reaction mechanism of MgH2, which is lithium-controlled, can be extended to others hydrides as: MH x + xLi(+) + xe(-) in equilibrium with M + xLiH. Other reaction paths-involving solid solutions, metastable distorted phases, and phases with low hydrogen content-were recently reported for TiH2 and Mg2FeH6, Mg2CoH5 and Mg2NiH4. The importance of fundamental aspects to overcome technological difficulties is discussed with a focus on conversion reaction limitations in the case of MgH2. The influence of MgH2 particle size, mechanical grinding, hydrogen sorption cycles, grinding with carbon, reactive milling under hydrogen, and metal and catalyst addition to the MgH2/carbon composite on kinetics improvement and reversibility is presented. Drastic technological improvement in order to the enhance conversion process efficiencies is needed for practical applications. The main goals are minimizing the impact of electrode volume variation during lithium extraction and overcoming the poor electronic conductivity of LiH. To use polymer binders to improve the cycle life of the hydride-based electrode and to synthesize nanoscale composite hydride can be helpful to address these drawbacks. The development of high-capacity hydride anodes should

  19. Analysis of barium hydroxide and calcium hydroxide slurry carbonation reactors

    International Nuclear Information System (INIS)

    Patch, K.D.; Hart, R.P.; Schumacher, W.A.

    1980-05-01

    The removal of CO 2 from air was investigated by using a continuous-agitated-slurry carbonation reactor containing either barium hydroxide [Ba(OH) 2 ] or calcium hydroxide [Ca(OH) 2 ]. Such a process would be applied to scrub 14 CO 2 from stack gases at nuclear-fuel reprocessing plants. Decontamination factors were characterized for reactor conditions which could alter hydrodynamic behavior. An attempt was made to characterize reactor performance with models assuming both plug flow and various degrees of backmixing in the gas phase. The Ba(OH) 2 slurry enabled increased conversion, but apparently the process was controlled under some conditions by phenomena differing from those observed for carbonation by Ca(OH) 2 . Overall reaction mechanisms are postulated

  20. Bronchography in dogs. Comparative study with two barium sulphate solutions

    International Nuclear Information System (INIS)

    Thibaut, J.; Gallardo, P.; Vargas, L.; Deppe, R.; Born, R.

    1998-01-01

    Two solutions of barium sulphate, 60 and 30% w/v, were compared with the ''overflow'' Bronchographic method. Two groups of eight healthy adult does of both sexes, weighing 7 to 18 kg were used for the study. The dogs were anaesthetised with thiopentone sodium 2% (20 mg/kg iv). After intubation, each dog received contrast medium by a catheter connected to a syringe, in a 9 mi dose. Two series of two x-rays plates were taken in left lateral recumbent, 3 and 6 min after administering the contrast medium and in ventrodorsal projection, 30 sec. later. The x-ray plates obtained were analysed and compared intra and inter group considering the advance speed of the contrast medium, the radiographic density and outlines. Adverse reactions were controlled

  1. Assessment of patient exposure for barium enema examinations

    International Nuclear Information System (INIS)

    Bednarek, D.R.; Rudin, S.; Wong, R.

    1983-01-01

    Methods are described for the assessment of patient exposure during clinical fluoroscopic procedures. Values of the roentgen-area-product (RAP) and their distribution throughout the examination are presented for both single-contrast and double-contrast barium enema studies. The double-contrast procedure was measured to give 50% more radiation to the patient than the single-contrast procedure when the same size optical aperture is used between the intensifier and TV pick-up tube. However, it was possible to decrease the fluoroscopic RAP value by over a factor of two for the double-contrast procedure without an adverse clinical effect by increasing the area of the aperture diaphragm

  2. Polarization switching kinetics in ultrathin ferroelectric barium titanate film

    Energy Technology Data Exchange (ETDEWEB)

    Gaynutdinov, R., E-mail: rgaynutdinov@gmail.com [Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Minnekaev, M., E-mail: m.minnekaev@gmail.com [NRNU Moscow Engineering Physics Institute, Moscow 115409 (Russian Federation); Mitko, S., E-mail: sergey_m@ntmdt.ru [NT-MDT Co., Moscow 124482 (Russian Federation); Tolstikhina, A., E-mail: alla@ns.crys.ras.ru [Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Zenkevich, A., E-mail: avzenkevich@mephi.ru [NRNU Moscow Engineering Physics Institute, Moscow 115409 (Russian Federation); NRC Kurchatov Institute, Moscow 123182 (Russian Federation); Ducharme, S., E-mail: sducharme@unl.edu [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, NE 68588-0299 (United States); Fridkin, V., E-mail: fridkin@ns.crys.ras.ru [Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation)

    2013-09-01

    The investigation of polarization switching kinetics in an ultrathin barium titanate film reveals true threshold switching at a large coercive electric field, evidence that switching is of intrinsic thermodynamic nature, rather than of extrinsic nature initiated by thermal nucleation, which has no true threshold field. The switching speed of a 7 nm thick epitaxial film exhibits a critical slowing as the threshold is approached from above, a key characteristic of intrinsic switching. In contrast, a bulk crystal exhibits nucleation-initiated switching, which has no threshold, and proceeds even at fields well below the nominal coercive field, which was determined independently from the polarization-electric field hysteresis loop. Previously, this phenomenon was only reported for ultrathin ferroelectric polymer Langmuir–Blodgett films. Since both the thermodynamic coercive field and the intrinsic switching kinetics are derived from the mean field theory of ferroelectricity, we expect that these phenomena will be found in other ferroelectric films at the nanoscale.

  3. X-ray and Moessbauer investigations of isotropic barium ferrites

    International Nuclear Information System (INIS)

    Kirichok, P.P.; Pashchenko, V.A.; Dem'yaniv, T.O.; Ryabova, G.N.; Lisovskij, A.M.

    1984-01-01

    Using the methods of X-ray and γ-resonance spectroscopy the crystal chemical and magnetic structure of isotropic barium hexaferrites is studied. compacting pressure the lattice parameter c of ferrite of the BaOx5.7Fe 2 O 3 is decreased and the diffraction line width on its X-ray p attern is increased. Due to increasing the isoststical compacting pressure quadrupole splitting of the γ-resonance absorption spectrum of 57 Fe nuclei in tetrahedral positions 4f 1 and in positions 2a decreases. The sintering temperature growth leads to increasing the lattice parameter c and diffraction line widths and decreasing the effeutive field values and isomeric s hifts on 57 Fe nuclei. Isostatical compacting pressure does not affect the electron configuration of iron ions

  4. Structural and functional characterization of barium zirconium titanate / epoxy composites

    Directory of Open Access Journals (Sweden)

    Filiberto González Garcia

    2011-12-01

    Full Text Available The dielectric behavior of composite materials (barium zirconium titanate / epoxy system was analyzed as a function of ceramic concentration. Structure and morphologic behavior of the composites was investigated by X-ray Diffraction (XRD, Fourier transformed infrared spectroscopy (FT-IR, Raman spectroscopy, field emission scanning electron microscopy (FE-SEM and transmission electron microscopy (TEM analyses. Composites were prepared by mixing the components and pouring them into suitable moulds. It was demonstrated that the amount of inorganic phase affects the morphology of the presented composites. XRD revealed the presence of a single phase while Raman scattering confirmed structural transitions as a function of ceramic concentration. Changes in the ceramic concentration affected Raman modes and the distribution of particles along into in epoxy matrix. Dielectric permittivity and dielectric losses were influenced by filler concentration.

  5. High Pressure X-ray Diffraction Studies on Barium.

    Science.gov (United States)

    Barnett, J D; Bennion, R B; Hall, H T

    1963-08-09

    Simultaneous x-ray diffraction and electrical resistance measurements on barium establish, with certainty, that Bridgman's 78-kb resistance transition is identical with his 59-kb volumetransition. During this transition, the bodycentered cubic structure changes to hexagonalclose packed. Lattice parameters for the latter structure at 62 kb (volume scale) are: a = 3.90 A, c = 6.15 A, and c/a = 1.58. Compression (AV/Vo) at 62 kb is 0.359 + 0.005 compared to 0.345 previously reported by Bridgman. Below the transition, at 49 kb, compression is 0.300 +/- 0.005 compared to Bridgman's 0.288. Bridgman's 17-kb volume transition was not detected by x-ray diffraction.

  6. Effect of Nb on barium titanate prepared from citrate solutions

    Directory of Open Access Journals (Sweden)

    Stojanović Biljana D.

    2002-01-01

    Full Text Available The influence of the addition of dopants on the microstructure development and electrical properties of BaTiO3 doped with 0.2, 0.4, 0.6, 0.8 mol% of Nb and 0.01 mol% of Mn based compounds was studied. Doped barium titanate was prepared using the polymeric precursor method from citrate solutions. The powders calcined at 700°C for 4 hours were analysed by infrared (IR spectroscopy to verify the presence of carbonates, and by X-ray diffraction (XRD for phase formation. The phase composition, microstructure and dielectric properties show a strong dependence on the amount of added niobium.

  7. Conoscopic study of strontium-barium niobate single crystals

    Science.gov (United States)

    Kolesnikov, Aleksandr; Grechishkin, Rostislav; Malyshkina, Olga; Malyshkin, Yury; Dec, Jan; Łukasiewicz, Tadeusz; Ivanova, Aleksandra

    2013-12-01

    Optically transparent single crystals of strontium-barium niobate, SrxBa1-xNb2O6, of different compositions (x = 0.26...0.7) were examined with the aid of conoscopic light interference figures. A regular change of the isochrome concentric ring number and diameters consistent with the temperature variation of the value of birefringence is demonstrated by direct observations of polar cuts of optically uniaxial samples. Anomalous violations of the conventional (uniaxial) interference patterns occur occasionaly in some samples being indicative of the existence of biaxial trait in their behaviour even though no voltage is applied. These features may depend on annealing treatments at elevated temperatures. The results of the study show that conoscopic images may serve as a sensitive indicator of the structural state of SBN crystals related to the effects of stress-induced change of optical anisotropy and temperature dependent birefringence parameters.

  8. Laser irradiation in Nd3+ doped strontium barium niobate glass

    International Nuclear Information System (INIS)

    Haro-Gonzalez, P.; Martin, I. R.; Arbelo-Jorge, E.; Gonzalez-Perez, S.; Caceres, J. M.; Nunez, P.

    2008-01-01

    A local nanocrystalline formation in a neodymium doped strontium barium niobate (SBN) glass has been obtained under argon laser irradiation. The intense emission around 880 nm, originated from the 4 F 3/2 ( 4 F 5/2 ) thermalized level when the glass structure changes to a glass ceramic structure due to the irradiation of the laser beam, has been studied. The intensities and lifetimes change from this level inside and outside the irradiated area made by the laser excitation. They have been analyzed and demonstrated that the desvitrification process has been successfully achieved. These results confirm that nanocrystals of SBN have been created by the laser action confirming that the transition from glass to glass ceramic has been completed. These results are in agreement with the emission properties of nanocrystals of the bulk glass ceramic sample. The present study also suggests that the SBN nanocrystal has a potential application as temperature detector

  9. Ultrasonic de-agglomeration of barium titanate powder.

    Science.gov (United States)

    Marković, S; Mitrić, M; Starcević, G; Uskoković, D

    2008-01-01

    BaTiO3 (BT) powder, with average particle size of 1.4 microm, was synthesized by solid-state reaction. A high-intensity ultrasound irradiation (ultrasonication) was used to de-agglomerate micro-sized powder to nano-sized one. The crystal structure, crystallite size, morphology, particle size, particle size distribution, and specific surface area of the BT powder de-agglomerated for different ultrasonication times (0, 10, 60, and 180 min) were determined. It was found that the particles size of the BT powder was influenced by ultrasonic treatment, while its tetragonal structure was maintained. Therefore, ultrasonic irradiation can be proposed as an environmental-friendly, economical, and effective tool for the de-agglomeration of barium titanate powders.

  10. Microscopic theory of the phonon frequencies in BCC barium

    International Nuclear Information System (INIS)

    Oli, B.A.

    1988-09-01

    The phonon dispersion frequencies are calculated from first principles for bbc barium using a resonance pseudopotential model which incorporates the effect of s-d hybridization. It was also possible using this scheme to account for the anomalous feature of the Ba dispersion curve observed experimentally in the (ξ,0,0) direction where the frequencies of the transverse branch are higher than the frequencies of the longitudinal branch. The frequencies obtained were also used to calculate the phonon density of states by the linear-analytic tetrahedra method of zone integration. The results of these calculations are qualitatively in good agreement with experimental data, and provide further support to the interpretation of the anomalous behaviour in the (ξ,0,0) direction as arising from s-d hybridization. (author). 27 refs, 4 figs, 3 tabs

  11. Barium titanate nanocomposite capacitor FY09 year end report.

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Tyler E.; DiAntonio, Christopher Brian; Yang, Pin; Chavez, Tom P.; Winter, Michael R.; Monson, Todd C.; Roesler, Alexander William; Fellows, Benjamin D.

    2009-11-01

    This late start RTBF project started the development of barium titanate (BTO)/glass nanocomposite capacitors for future and emerging energy storage applications. The long term goal of this work is to decrease the size, weight, and cost of ceramic capacitors while increasing their reliability. Ceramic-based nanocomposites have the potential to yield materials with enhanced permittivity, breakdown strength (BDS), and reduced strain, which can increase the energy density of capacitors and increase their shot life. Composites of BTO in glass will limit grain growth during device fabrication (preserving nanoparticle grain size and enhanced properties), resulting in devices with improved density, permittivity, BDS, and shot life. BTO will eliminate the issues associated with Pb toxicity and volatility as well as the variation in energy storage vs. temperature of PZT based devices. During the last six months of FY09 this work focused on developing syntheses for BTO nanoparticles and firing profiles for sintering BTO/glass composite capacitors.

  12. Study on a flexoelectric microphone using barium strontium titanate

    International Nuclear Information System (INIS)

    Kwon, S R; Huang, W B; Yuan, F G; Jiang, X N; Zhang, S J

    2016-01-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba 0.65 Sr 0.35 TiO 3 ) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications. (paper)

  13. Study on a flexoelectric microphone using barium strontium titanate

    Science.gov (United States)

    Kwon, S. R.; Huang, W. B.; Zhang, S. J.; Yuan, F. G.; Jiang, X. N.

    2016-04-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba0.65Sr0.35TiO3) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications.

  14. The Performance of Barium Sulfate Nanoparticles/polypropylene Hybrid Multifilament

    Science.gov (United States)

    Li, Ying; Wang, Xuanjun; Mu, Xiaoxi; Zhang, Shujuan

    2012-01-01

    Nanosize barium sulfate (BaSO4) particles prepared with dodecyl benzene sulfonic acid (DBSA) in ethanol-water reaction system are used to prepare BaSO4/polypropylene (PP) nanocomposites by melt mixing method. It is then made into hybrid fibers by melt spinning and subsequent drawing with different ratios. The hybrid fibers are characterized by rheology, morphology, thermal stability and mechanical properties, respectively. The results indicate that the DBSA-modified BaSO4 can improve the spinnability of BaSO4/PP hybrid multifilament even at high BaSO4 nanoparticles concentration. DBSA can be used as compatibilizer to enhance the interface interaction of BaSO4/PP nanocomposites, because DBSA contains both hydrophobicity long alkyl chain and hydrophilic sulfonic group. Therefore, it can improve the performances of BaSO4/PP hybrid multifilament.

  15. Effect of hydrides on the ductile-brittle transition in stress-relieved, recrystallized and beta-treated zircaloy-4

    International Nuclear Information System (INIS)

    Pelchat, J.; Barcelo, F.

    1991-01-01

    This paper is concerned with the influence of δ-hydrides on the mechanical properties of three heat treated cold-rolled Zircaloy-4 sheets (stress-relieved, recrystallized and β treated), tested at room temperature and 350 0 C. Smooth tensile specimens of two thicknesses: 0.5 and 3.1 mm, containing different hydride volume fractions, up to 18% (about 1400 ppm H), have been tested. Metallographic and fractographic analysis were carried out in order to examine the fracture morphology near and on the fracture surface, and to determine the evolution of the fracture mechanism of hydrides as a function of temperature, hydride orientation and volume fraction

  16. Hydride Microstructure at the Metal-Oxide Interface of Zircaloy-4 from H.B. Robinson Nuclear Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cinbiz, Mahmut N [ORNL; Edmondson, Philip D [ORNL; Terrani, Kurt A [ORNL

    2017-01-01

    This study investigates the hydride rim microstructure at the metal-oxide interface of Zircaloy-4 cladding segment removed from H.B. Robinson Nuclear Reactor by utilizing high resolution electron microscopy techniques with energy dispersive x-ray spectroscopy at Oak Ridge National Laboratory under the NSUF Rapid Turnout Experiment program. A complex stacking and orientation of hydride platelets has been observed below the sub-oxide layer. Furthermore, radial hydride platelets have been observed. EDS signals of both Fe and Cr has been reduced within hydrides whereas EDS signal of Sn is unaffected.

  17. Hydrides formation In Zircaloy-4 irradiated with neutrons

    International Nuclear Information System (INIS)

    Vizcaino, P; Flores, A V; Vicente Alvarez, M A; Banchik, A.D; Tolley, A; Condo, A; Santisteban, J R

    2012-01-01

    Under reactor operating conditions zirconium components go through transformations which affect their original properties. Two phenomena of significant consequences for the integrity of the components are hydrogen uptake and radiation damage, since both contribute to the material fragilization. In the case of the Atucha I nuclear power reactor, the cooling channels, Zircaloy-4 tubular structural components about 6 meters long, were designed to withstand the entire lifetime of the reactor. Inside them, fuel elements 5.3 meters long are located. The fuel elements are cooled by a heavy water flow which circulates from the bottom (250 o ) to the top of the reactor (305 o C). The channels are affected by a fast neutron flux (En>1 Mev), increasing from a nominal value of 1.35 x 10 13 neutrons/cm 2 sec at the bottom to 1.69 x 10 13 neutrons/cm 2 sec at the top, reaching a maximum value of 3.76 x 10 13 neutrons/cm 2 sec at the center of the channels. However, due to the reactor operating conditions, they are replaced after about 10 effective full power years, time at which they reach 10 22 neutrons/cm 2 at the most neutronically active regions of the reactor. Studies on cooling channels are meaningful from many points of view. The channels are structural components which do not work under internal pressure or any other type of structural stress. The typical temperature of the cladding tubes in the reactor is about 350 o C, at which many types of irradiation defects are annealed [1]. The temperature range of the cooling channels lies between 200 o C-235 o C (outer foil of the channels) and 260 o C-300 o C (internal tube), a difference which makes the defect recovery kinetics slower. In the present context, following the program developed in the research contract 15810, we continue with the work started on the effects of the radiation on the hydride formation focusing on the dislocation loops in the zirconium matrix and its possible role as preferential sites for hydride

  18. Association between esophageal dysmotility and gastroesophaeal reflux on barium studies

    International Nuclear Information System (INIS)

    Campbell, Craig; Levine, Marc S.; Rubesin, Stephen E.; Laufer, Igor; Redfern, Gina; Katzka, David A.

    2006-01-01

    Objective: To determine whether there is an association between abnormal primary peristalsis in the esophagus and gastroesophageal reflux (GER) on barium studies. Methods: A computerized search of radiologic reports revealed 151 patients with esophageal dysmotility (characterized by intermittently decreased or absent peristalsis in the esophagus on upper gastrointestinal tract examinations) who fulfilled our study's entry criteria. These 151 patients were stratified into two groups depending on whether this dysmotility was associated with nonperistaltic contractions (NPCs): 92 patients had no NPCs (Dysmotility and No NPCs Group) and 59 had NPCs (Dysmotility and NPCs Group). An age-matched control group of 92 patients with normal motility was also generated from the radiologic reports. The reports were also reviewed for the presence and degree of GER and other complications of GER. The frequency and degree of GER were tabulated for each group, and the data were analyzed using a Pearson chi square test to determine if significant differences were present in the frequency and degree of GER or other findings among the groups. Results: The frequency of GER was significantly higher in patients with abnormal peristalsis and no NPCs than in controls (p = 0.02). When GER was stratified based on the degree of reflux, the frequency of moderate-to-marked GER was significantly higher in patients with abnormal peristalsis and no NPCs than in patients with abnormal peristalsis and NPCs (p = 0.01) or in controls (p = 0.0031). The frequency of reflux esophagitis also was significantly higher in patients with abnormal peristalsis and no NPCs than in controls (p = 0.04). Conclusion: Our findings suggest that patients with esophageal dysmotility characterized by intermittently decreased or absent peristalsis without NPCs have a significantly higher frequency and degree of GER than patients with normal motility. The presence of this specific form of esophageal dysmotility on barium

  19. Association between esophageal dysmotility and gastroesophaeal reflux on barium studies

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Craig [Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104 (United States); Levine, Marc S. [Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104 (United States)]. E-mail: marc.levine@uphs.upenn.edu; Rubesin, Stephen E. [Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104 (United States); Laufer, Igor [Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104 (United States); Redfern, Gina [Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104 (United States); Katzka, David A. [Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2006-07-15

    Objective: To determine whether there is an association between abnormal primary peristalsis in the esophagus and gastroesophageal reflux (GER) on barium studies. Methods: A computerized search of radiologic reports revealed 151 patients with esophageal dysmotility (characterized by intermittently decreased or absent peristalsis in the esophagus on upper gastrointestinal tract examinations) who fulfilled our study's entry criteria. These 151 patients were stratified into two groups depending on whether this dysmotility was associated with nonperistaltic contractions (NPCs): 92 patients had no NPCs (Dysmotility and No NPCs Group) and 59 had NPCs (Dysmotility and NPCs Group). An age-matched control group of 92 patients with normal motility was also generated from the radiologic reports. The reports were also reviewed for the presence and degree of GER and other complications of GER. The frequency and degree of GER were tabulated for each group, and the data were analyzed using a Pearson chi square test to determine if significant differences were present in the frequency and degree of GER or other findings among the groups. Results: The frequency of GER was significantly higher in patients with abnormal peristalsis and no NPCs than in controls (p = 0.02). When GER was stratified based on the degree of reflux, the frequency of moderate-to-marked GER was significantly higher in patients with abnormal peristalsis and no NPCs than in patients with abnormal peristalsis and NPCs (p = 0.01) or in controls (p = 0.0031). The frequency of reflux esophagitis also was significantly higher in patients with abnormal peristalsis and no NPCs than in controls (p = 0.04). Conclusion: Our findings suggest that patients with esophageal dysmotility characterized by intermittently decreased or absent peristalsis without NPCs have a significantly higher frequency and degree of GER than patients with normal motility. The presence of this specific form of esophageal dysmotility on

  20. Qualitative analysis of barium particles coated in small intestinal mucosa of rabbit by using scanning electron microscopy

    International Nuclear Information System (INIS)

    Lee, Yong Suk; Ha, Hyun Kwon; Lee, Yang Seob; Kim, Jae Kyun; Yoon, Seong Eon; Kim, Jung Hoon; Chung, Dong Jin; Auh, Yong Ho

    1998-01-01

    To qualitatively analysed barium coating status in the intestinal mucosa, we used scanning electron microscopy to observe barium particles coated in the small intestinal mucosa of rabbit, and we attempted to assess the relationship between electron microscopic findings and radiographic densities. Six different combination of barium and methylcellulose suspensions were infused into the resected small intestines of 15 rabbits. Barium powders were mixed with water to make 40% and 70% w/v barium solutions, and also mixed with 0.5% methylcellulose solutions were used as a double contrast agent. After the infusion of barium suspensions, a mammography unit was used to obtain radiographs of the small intestine, and their optical densities were measured by a densitometer. Thereafter, photographs of barium-coated small intestinal mucosa were obtained using a scanning electron microscope (x 8,000), and the number of barium particles in the unit area were measured. To compare the relationship between the electron microscopic findings and optical densities, statistical analysis using Spearman correlation was performed. This study shows that by using scanning electron microscopy, barium particles coated on the small intestinal mucosa can be qualitatively analysed. It also shows that the number of small barium particles measured by scanning electron microscopy is related to optical densities. (author). 14 refs., 2 figs

  1. Accommodation stresses in hydride precipitates by synchrotron x-ray diffraction

    International Nuclear Information System (INIS)

    Santisteban, J R; Vicente, M A; Vizcaino, P; Banchik, A D; Almer, J

    2012-01-01

    Hydride-forming materials (Zr, Ti, Nb, etc) are affected by a sub-critical crack growth mechanism that involves the diffusion of H to the stressed region ahead of a crack, followed by nucleation and fracture of hydrides at the crack tip [1]. The phenomenon is intermittent, with the crack propagating through the hydride and stopping when it reaches the matrix. By repeating these processes, the crack propagates through a component at a rate that is highly dependent on the temperature history of the component. Most research effort to understand this phenomenon has occurred within the nuclear industry, as it affects the safe operation of pressure tubes (Zr2.5%Nb) and the long-term storage of nuclear fuel (Zircaloy cladding). Stress-induced hydride formation is a consequence of the volume dilatation that accompanies hydride formation (of the order of 15%), which is elastoplastically accommodated by the matrix and precipitate. Compressive stresses are expected within hydride precipitates due to the constraint imposed by the matrix. Such 'accommodation' stresses are essential ingredients in all theoretical models developed to assess the crack growth rate dependence on operational variables such as temperature, applied stress intensity factor, or overall H concentration [2]. Yet little experimental information is available about the magnitude and directionality of such accommodation stresses. Synchrotron X-ray diffraction is the only technique capable of quantifying such stresses. Here we briefly describe the fundaments of the technique, when used through an area detector placed in transmission geometry. The results of the experiments have allowed us to produce a comprehensive picture about the magnitude and origin of accommodation stresses in δ zirconium hydride platelets (author)

  2. Proton and hydride affinities in excited states: magnitude reversals in proton and hydride affinities between the lowest singlet and triplet states of annulenyl and benzannulenyl anions and cations

    DEFF Research Database (Denmark)

    Rosenberg, Martin; Ottosson, Henrik; Kilså, Kristine

    2010-01-01

    electron counting rules for aromaticity in the two states. Using quantum chemical calculations at the G3(MP2)//(U)B3LYP/6-311+G(d,p) level we have examined the validity of this hypothesis for eight proton and eight hydride addition reactions of anions and cations, respectively, of annulenyl...

  3. High-Frequency H-1 NMR Chemical Shifts of Sn-II and Pb-II Hydrides Induced by Relativistic Effects: Quest for Pb-II Hydrides

    Czech Academy of Sciences Publication Activity Database

    Vícha, J.; Marek, R.; Straka, Michal

    2016-01-01

    Roč. 55, č. 20 (2016), s. 10302-10309 ISSN 0020-1669 Institutional support: RVO:61388963 Keywords : hydrides of TlI and PbII * high-frequency 1H chemical shifts * relativistic effects Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.857, year: 2016

  4. Trapping interference effects of arsenic, antimony and bismuth hydrides in collection of selenium hydride within iridium-modified transversally-heated graphite tube atomizer

    Czech Academy of Sciences Publication Activity Database

    Furdíková, Zuzana; Dočekal, Bohumil

    2009-01-01

    Roč. 64, č. 4 (2009), s. 323-328 ISSN 0584-8547 R&D Projects: GA ČR GA203/06/1441 Institutional research plan: CEZ:AV0Z40310501 Keywords : selenium hydride trapping * arsine * stibine Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.719, year: 2009

  5. Trapping of hydride forming elements within miniature electrothermal devices. Part 3. Investigation of collection of antimony and bismuth on a molybdenum foil strip following hydride generation

    Czech Academy of Sciences Publication Activity Database

    Krejčí, Pavel; Dočekal, Bohumil; Hrušovská, Zuzana

    2006-01-01

    Roč. 61, č. 4 (2006), s. 444-449 ISSN 0584-8547 R&D Projects: GA AV ČR(CZ) IAA400310507 Institutional research plan: CEZ:AV0Z40310501 Keywords : bismuth ine * stibine * hydride trapping Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.092, year: 2006

  6. Sensitivity of single contrast barium enema with regard to colorectal disease as diagnosed by colonoscopy

    International Nuclear Information System (INIS)

    Kaude, J.V.; Harty, R.F.

    1982-01-01

    The results of single contrast barium enema were retrospectively correlated with colonoscopically diagnosed colorectal disease in 54 patients (75 lesions). Altogether 66 lesions (88%) were correctly diagnosed. The sensitivity of barium enema for polyps was 81% (26/32). There were three perceptive errors and three polyps 5 mm or less in size were not demonstrated by barium enema. Twenty-nine cases of inflammatory disorders were all correctly diagnosed. One of 12 malignancies was missed by perceptive error. In two cases with vascular malformations the barium enema was normal. 4/9 (44%) of missed lesions were perceptive errors and could have been probably avoided by a second independent reading of films. (orig.)

  7. Severe acute cholangitis after endoscopic sphincterotomy induced by barium examination: A case report.

    Science.gov (United States)

    Zhang, Zhen-Hai; Wu, Ya-Guang; Qin, Cheng-Kun; Su, Zhong-Xue; Xu, Jian; Xian, Guo-Zhe; Wu, Shuo-Dong

    2012-10-21

    Endoscopic sphincterotomy (EST) is considered as a possible etiological factor for severe cholangitis. We herein report a case of severe cholangitis after endoscopic sphincterotomy induced by barium examination. An adult male patient presented with epigastric pain was diagnosed as having choledocholithiasis by ultrasonography. EST was performed and the stone was completely cleaned. Barium examination was done 3 d after EST and severe cholangitis appeared 4 h later. The patient was recovered after treated with tienam for 4 d. Barium examination may induce severe cholangitis in patients after EST, although rare, barium examination should be chosen cautiously. Cautions should be also used when EST is performed in patients younger than 50 years to avoid the damage to the sphincter of Oddi.

  8. Barium borate β-BaB2O4 as a material for nonlinear optics

    International Nuclear Information System (INIS)

    Fedorov, Pavel P; Kokh, Aleksandr E; Kononova, Nadezhda G

    2002-01-01

    Data on the structure, polymorphism, phase equilibria, growth techniques, properties and applications of single crystals of the low-temperature modification of barium borate are analysed. The bibliography includes 201 references.

  9. 21 CFR 201.304 - Tannic acid and barium enema preparations.

    Science.gov (United States)

    2010-04-01

    ... number of deaths associated with the addition of tannic acid to barium enemas. There is a lack of...(f) of the Federal Food, Drug, and Cosmetic Act unless the label and the labeling bear conspicuously...

  10. Influence of hydrides orientation on strain, damage and failure of hydrided zircaloy-4; Influence de l'orientation des hydrures sur les modes de deformation, d'endommagement et de rupture du zircaloy-4 hydrure

    Energy Technology Data Exchange (ETDEWEB)

    Racine, A

    2005-09-15

    In pressurized water reactors of nuclear power plants, fuel pellets are contained in cladding tubes, made of Zirconium alloy, for instance Zircaloy-4. During their life in the primary water of the reactor (155 bars, 300 C), cladding tubes are oxidized and consequently hydrided. A part of the hydrogen given off precipitates as Zirconium hydrides in the bulk material and embrittles the material. This embrittlement depends on many parameters, among which hydrogen content and orientation of hydrides with respect to the applied stress. This investigation is devoted to the influence of the orientation of hydrides with respect to the applied stress on strain, damage and failure mechanisms. Macroscopic and SEM in-situ ring tensile tests are performed on cladding tube material (unirradiated cold worked stress-relieved Zircaloy-4) hydrided with about 200 and 500 wppm hydrogen, and with different main hydrides orientation: either parallel or perpendicular to the circumferential tensile direction. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. Neither the tensile stress-strain response nor the global and local strain modes are significantly affected by hydrogen content or hydride orientation, but the failure modes are strongly modified. Indeed, only 200 wppm radial hydrides embrittle Zy-4: sample fail in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases sample reach at least 750 MPa before necking and final failure, in ductile or brittle mode. To model this particular heterogeneous material behavior, a non-coupled damage approach which takes into account the anisotropic distribution of the hydrides is proposed. Its parameters are identified from the macroscopic strain field measurements and a

  11. Delayed hydride cracking: alternative pre-cracking method

    International Nuclear Information System (INIS)

    Mieza, Juan I.; Ponzoni, Lucio M.E.; Vigna, Gustavo L.; Domizzi, Gladys

    2009-01-01

    The internal components of nuclear reactors built-in Zr alloys are prone to a failure mechanism known as Delayed Hydride Cracking (DHC). This situation has triggered numerous scientific studies in order to measure the crack propagation velocity and the threshold stress intensity factor associated to DHC. Tests are carried out on fatigued pre-crack samples to ensure similar test conditions and comparable results. Due to difficulties in implementing the fatigue pre-crack method it would be desirable to replace it with a pre-crack produced by the same process of DHC, for which is necessary to demonstrate equivalence of this two methods. In this work tests on samples extracted from two Zr-2.5 Nb tubes were conducted. Some of the samples were heat treated to obtain a range in their metallurgical properties as well as different DHC velocities. A comparison between velocities measured in test samples pre-cracked by fatigue and RDIH is done, demonstrating that the pre-cracking method does not affect the measured velocity value. In addition, the incubation (t inc ), which is the time between the application of the load and the first signal of crack propagation, in samples pre-cracked by RDIH, was measured. It was found that these times are sufficiently short, even in the worst cases (lower speed) and similar to the ones of fatigued pre-cracked samples. (author)

  12. Pressure and high-Tc superconductivity in sulfur hydrides

    Science.gov (United States)

    Gor'Kov, Lev P.; Kresin, Vladimir Z.

    2016-05-01

    The paper discusses fundamentals of record-TC superconductivity discovered under high pressure in sulfur hydride. The rapid increase of TC with pressure in the vicinity of Pcr ≈ 123GPa is interpreted as the fingerprint of a first-order structural transition. Based on the cubic symmetry of the high-TC phase, it is argued that the lower-TC phase has a different periodicity, possibly related to an instability with a commensurate structural vector. In addition to the acoustic branches, the phonon spectrum of H3S contains hydrogen modes with much higher frequencies. Because of the complex spectrum, usual methods of calculating TC are here inapplicable. A modified approach is formulated and shown to provide realistic values for TC and to determine the relative contributions of optical and acoustic branches. The isotope effect (change of TC upon Deuterium for Hydrogen substitution) originates from high frequency phonons and differs in the two phases. The decrease of TC following its maximum in the high-TC phase is a sign of intermixing with pairing at hole-like pockets which arise in the energy spectrum of the cubic phase at the structural transition. On-pockets pairing leads to the appearance of a second gap and is remarkable for its non-adiabatic regime: hydrogen mode frequencies are comparable to the Fermi energy.

  13. Metal Borohydrides synthesized from metal borides and metal hydrides

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    Metal Borohydrides Synthesized from Metal Borides and Metal Hydrides Alexander Fogha, Sanna Sommera, Kasper T. Møllera, T. R. Jensena aCenter for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO) and Chemistry Department, Aarhus University, Langelandsgade 140, DK-8000...... Aarhus C, Denmark email: gallafogh@hotmail.com / sanna-sommer@hotmail.com Magnesium boride, MgB2, ball milled with MH (M = Li, Na, Ca) followed by hydrogenation under high hydrogen pressure, readily forms the corresponding metal borohydrides, M(BH4)x (M = Li, Na, Ca) and MgH2 according to reaction scheme...... and Ca(BH4)2, respectively [3,4]. An attempt to synthesize alkali and alkaline earth metal borohydrides from various borides by ball milling under high hydrogen pressure is presented here. MgB2, AlB2 and CaB6 have been milled with MHx (M = Li, Na, Mg, Ca) at p(H2) = 110 bar for 24 hours. All samples were...

  14. Alternatives for metal hydride storage bed heating and cooling

    International Nuclear Information System (INIS)

    Fisher, I.A.; Ramirez, F.B.; Koonce, J.E.; Ward, D.E.; Heung, L.K.; Weimer, M.; Berkebile, W.; French, S.T.

    1991-01-01

    The reaction of hydrogen isotopes with the storage bed hydride material is exothermic during absorption and endothermic during desorption. Therefore, storage bed operation requires a cooling system to remove heat during absorption, and a heating system to add the heat needed for desorption. Three storage bed designs and their associated methods of heating and cooling and accountability are presented within. The first design is the current RTF (Replacement Tritium Facility) nitrogen heating and cooling system. The second design uses natural convection cooling with ambient glove box nitrogen and electrical resistance for heating. This design is referred to as the Naturally Cooled/Electrically Heated (NCEH) design. The third design uses forced convection cooling with ambient glove box nitrogen and electrical resistance for heating. The design is referred to as the Forced Convection Cooled/Electrically Heated (FCCEH) design. In this report the operation, storage bed design, and equipment required for heating, cooling, and accountability of each design are described. The advantages and disadvantages of each design are listed and discussed. Based on the information presented within, it is recommended that the NCEH design be selected for further development

  15. Solid State NMR Studies of the Aluminum Hydride Phases

    Science.gov (United States)

    Hwang, Son-Jong; Bowman, R. C., Jr.; Graetz, Jason; Reilly, J. J.

    2006-01-01

    Several solid state NMR techniques including magic-angle-spinning (MAS) and multiple-quantum (MQ) MAS experiments have been used to characterize various AlH3 samples. MAS-NMR spectra for the 1H and 27Al nuclei have been obtained on a variety of AlH3 samples that include the (beta)- and (gamma)- phases as well as the most stable (alpha)-phase. While the dominant components in these NMR spectra correspond to the aluminum hydride phases, other species were found that include Al metal, molecular hydrogen (H2), as well as peaks that can be assigned to Al-O species in different configurations. The occurrence and concentration of these extraneous components are dependent upon the initial AlH3 phase composition and preparation procedures. Both the (beta)-AlH3 and (gamma)-AlH3 phases were found to generate substantial amounts of Al metal when the materials were stored at room temperature while the (alpha)-phase materials do not exhibit these changes.

  16. Aluminum hydride cations stabilized by weakly coordinating carbaalanates.

    Science.gov (United States)

    Stasch, Andreas; Roesky, Herbert W; Noltemeyer, Mathias; Schmidt, Hans-Georg

    2005-08-08

    The reactions of t-BuCCLi with a mixture of AlH(3).NMe(3) and ClAlH(2).NMe(3) in boiling toluene with the addition of [t-BuCH(2)(Bzl)NMe(2)]Cl, or a bulky beta-diketimine instead, and [n-Bu(4)N]Cl led to the carbaalanates [H(2)Al(NMe(3))(2)](2)[(AlH)(8)(CCH(2)t-Bu)(6)], 3, and [n-Bu(4)N](2)[(AlH)(8)(CCH(2)t-Bu)(6)], 4, respectively. The reaction of Me(3)N.Al(CCt-Bu)(3) 5 and AlH(3).NMe(3) in boiling toluene yielded [H(n-Bu)Al(NMe(3))(2)][(AlH)(7)(AlNMe(3))(CCH(2)t-Bu)(6)], 6, in trace amounts. The single-crystal X-ray structures of 3 and 6 are reported. The compounds 3, 4, and 6 consist of well-separated ion pairs introducing carbaalanates as weakly coordinating anions and stabilizing aluminum hydride cations.

  17. Studying aluminum hydride by means of thermal analysis

    Science.gov (United States)

    Milekhin, Yu. M.; Koptelov, A. A.; Matveev, A. A.; Baranets, Yu. N.; Bakulin, D. A.

    2015-07-01

    Chemical reactions and physical transformations that occur upon heating aluminum hydride (AlH3, alane), stored for 25 years, in the temperature range of 50-1200°C in an atmosphere of nitrogen, argon, and air are studied by means of thermogravimetric analysis and differential scanning calorimetry. The heat of thermal decomposition and the hydrogen content are determined for the AlH3 samples and are found to be 318 ± 25 J/g and 9.32 ± 0.24 wt %, respectively. It is established that the estimated enthalpy of formation of AlH3 in stoichiometric composition (Δf H ≈ -10.3 kJ/mol) agrees with the literature data. After the release of hydrogen, the mass of the precipitate increases by 0.5 ± 0.3%, relative to the initial mass of the AlH3 samples; the most likely reason for this effect is the adsorption of nitrogen (argon) in the micropores and mesopores that form. Thermal phenomena associated with the crystallization of the amorphous aluminum that forms after hydrogen is released from the alane particles are analyzed. It is established that the aluminum contained in initial AlH3 samples is almost completely transformed into aluminum nitride and oxide (AlN and Al3O3) upon heating to 1200°C in nitrogen and air, respectively.

  18. On the thermodynamics of phase transitions in metal hydrides

    Science.gov (United States)

    di Vita, Andrea

    2012-02-01

    Metal hydrides are solutions of hydrogen in a metal, where phase transitions may occur depending on temperature, pressure etc. We apply Le Chatelier's principle of thermodynamics to a particular phase transition in TiH x , which can approximately be described as a second-order phase transition. We show that the fluctuations of the order parameter correspond to fluctuations both of the density of H+ ions and of the distance between adjacent H+ ions. Moreover, as the system approaches the transition and the correlation radius increases, we show -with the help of statistical mechanics-that the statistical weight of modes involving a large number of H+ ions (`collective modes') increases sharply, in spite of the fact that the Boltzmann factor of each collective mode is exponentially small. As a result, the interaction of the H+ ions with collective modes makes a tiny suprathermal fraction of the H+ population appear. Our results hold for similar transitions in metal deuterides, too. A violation of an -insofar undisputed-upper bound on hydrogen loading follows.

  19. Hydrogen storage in lithium hydride: A theoretical approach

    Science.gov (United States)

    Banger, Suman; Nayak, Vikas; Verma, U. P.

    2018-04-01

    First principles calculations have been carried out to analyze structural stability of lithium hydride (LiH) in NaCl phase using the full potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT). Calculations have been extended to physiosorbed H-atom compounds LiH·H2, LiH·3H2 and LiH·4H2. The obtained results are discussed in the paper. The results for LiH are in excellent agreement with earlier reported data. The obtained direct energy band gap of LiH is 3.0 eV which is in excellent agreement with earlier reported theoretical band gap. The electronic band structure plots of the hydrogen adsorbed compounds show metallic behavior. The elastic constants, anisotropy factor, shear modulus, Young's modulus, Poisson's ratio and cohesive energies of all the compounds are calculated. Calculation of the optical spectra such as the real and imaginary parts of dielectric function, optical reflectivity, absorption coefficient, optical conductivity, refractive index, extinction coefficient and electron energy loss are performed for the energy range 0-15 eV. The obtained results for LiH·H2, LiH·3H2 and LiH·4H2, are reported for the first time. This study has been made in search of materials for hydrogen storage. It is concluded that LiH is a promising material for hydrogen storage.

  20. Delayed hydride cracking of Zircaloy-4 fuel cladding

    International Nuclear Information System (INIS)

    Pizarro, Luis M.; Fernandez, Silvia; Lafont, Claudio; Mizrahi, Rafael; Haddad, Roberto

    2007-01-01

    Crack propagation rates, grown by the delayed hydride cracking mechanism, were measured in Zircaloy-4 fuel cladding, according to a Coordinated Research Project (CRP) sponsored by the International Atomic Energy Agency (IAEA). During the first stage of the program a Round Robin Testing was performed on fuel cladding samples provided by Studsvik (Sweden), of the type used in PWR reactors. Crack growth in the axial direction is obtained through the specially developed 'pin load testing' (PLT) device. In these tests, crack propagation rates were determined at 250 C degrees on several samples of the material described above, obtaining a mean value of about 2.5 x 10 -8 m s -1 . The results were analyzed and compared satisfactorily with those obtained by the other laboratories participating in the CRP. At the present moment, similar tests on CANDU and Atucha I type fuel cladding are being performed. It is thought that the obtained results will give valuable information concerning the analysis of possible failures affecting fuel cladding under reactor operation. (author) [es