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Sample records for hydrogen absorption characteristics

  1. Synthesis of Nanocrystalline SnO2 Microspheres and Their Hydrogen Absorption Characteristics.

    PubMed

    Wang, Zhiyuan; Wang, Fengping; Li, Mingyan; Iqbal, M Zubair; Javed, Qurat-Ul-Ain; Lu, Yanzhen; Xu, Mei; Li, Quanshui

    2015-02-01

    SnO2 solid microspheres and multilayered nanocrystalline SnO2 hollow microspheres (MHS-SnO2) have been successfully synthesized in the solvothermal environment by using different solvents. The morphology, structure and composition of the as-prepared products are characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED) and X-ray diffraction (XRD). The growth mechanism of SnO2 solid microspheres and MHS-SnO2 are proposed and attributed to the viscosity of solvent. The studies on hydrogen absorption characteristics of SnO2 solid structure and MHS-SnO2 show an absorption capability of 0.50 wt.% and 0.92 wt.%, respectively.

  2. A first-principles study on interaction of Mg/Ni interface and its hydrogen absorption characteristics

    NASA Astrophysics Data System (ADS)

    Chen, Yuying; Dai, Jianhong; Xie, Ruiwen; Song, Yan

    2016-07-01

    We have investigated the interaction of Mg/Ni interface and its hydrogen adsorption characteristics using first-principles calculations to obtain a better understanding of the Mg/Ni interface as a hydrogen storage material. The smallest work of adhesion of Mg/Ni interface is 4.28 J/m2 with AB stacking sequence in the studied systems. Hydrogen adsorption energy and electronic structures were evaluated to study the interaction characteristics between hydrogen and Mg/Ni interface. The hydrogen adsorption is energetically favored on all considered sites. The hydrogen atom prefers to adsorb on the tetrahedral site of the Ni side of the interface owning the lowest adsorption energy. The plane-averaged charge density and the density of states analysis indicate that the absorption of hydrogen could stabilize the Mg/Ni interface owing to the strongly bonding interactions between hydrogen atom and the host Mg and Ni atoms. Therefore, Mg/Ni interface provides a promising medium for hydrogen storage.

  3. Facile synthesis of self-assembled SnO nano-square sheets and hydrogen absorption characteristics

    SciTech Connect

    Iqbal, M. Zubair; Wang, Fengping; Feng, Ting; Zhao, Hailei; Rafique, M. Yasir; Rafi ud Din; Farooq, M. Hassan; Javed, Qurat ul ain; Khan, Dil Faraz

    2012-11-15

    hydrogen absorption characteristics of SnO nano-square sheets performed at 373 K shows good absorption capacity of 1.194 wt.%.

  4. Hydrogen Absorption by Niobium.

    DTIC Science & Technology

    1982-04-13

    incorporate an independent means for ascertaining surface cleanliness (e.g. AES). The form of the absorption curve in Fig. 7 appears to agree with that...very interesting study and is well within the capabilities of the systen designed, if the surface cleanliness can be assured. Wire specimens have a...assessing surface cleanliness would be an important supporting technique for understanding the results of these measurements. The simple kinetic

  5. Hydrogen absorption and desorption kinetics in fullerite C60 single crystals. Low-temperature micromechanical and structural characteristics of the interstitial solid solution C60(H2)x

    NASA Astrophysics Data System (ADS)

    Fomenko, L. S.; Lubenets, S. V.; Natsik, V. D.; Stetsenko, Yu. E.; Yagotintsev, K. A.; Strzhemechny, M. A.; Prokhvatilov, A. I.; Osipyan, Yu. A.; Izotov, A. N.; Sidorov, N. S.

    2008-01-01

    The microhardness HV and lattice parameter a of C60 single crystals are measured at room temperature as functions of the hydrogen saturation time t for several values of the saturation temperature (250, 300, and 350°C) at a fixed hydrogen pressure p =30atm. According to the measurements of HV and a, the kinetics of hydrogen absorption is described by a simple exponential law with a single, temperature-dependent characteristic time. In highly saturated samples the microhardness is 4 times greater than for the initial C60 crystal, while the lattice parameter is 0.2% larger. The temperature dependence of the microhardness HV and lattice parameter a of C60(H2)x crystals is investigated in the temperature interval 77-300K. The introduction of hydrogen lowers the temperature of the fcc-sc phase transition, and the transition becomes strongly broadened in temperature. The dependence of the microhardness of the saturated sample on the hold time in air at room temperature is described by the sum of two exponentials with different characteristic times. Kinetics of this kind is presumably due to two processes: desorption of hydrogen from the sample, which causes a decrease of the microhardness, and a simultaneous penetration of gaseous impurities into the sample from the surrounding air, which is accompanied by hardening. The influence of the H2 molecules on the characteristic of the intermolecular interaction in fullerite C60 is discussed and the intercalation-induced processes of dislocation slip and microfracture.

  6. Vacuum ultraviolet absorption in a hydrogen arcjet

    NASA Technical Reports Server (NTRS)

    Manzella, David H.; Cappelli, Mark A.

    1992-01-01

    Atomic absorption spectroscopy was utilized to measure the ground state atomic hydrogen number density in the plasma produced in a low power hydrogen arcjet. A microwave driven hydrogen plasma was used as the source of radiation resonant with the vacuum ultraviolet Lyman alpha transition. The suitability of this radiation source is discussed. The optical depth of this transition prevented measurements at locations where the ground state atomic hydrogen number density was larger than 3 x 10 exp 19/cu m. These results indicate that other single-photon optical diagnostic techniques are equally ineffective in locations of higher hydrogen number density unless the spectral line shape of the atomic hydrogen absorbers is known.

  7. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  8. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  9. Ultraviolet absorption cross sections of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Lin, C. L.; Rohatgi, N. K.; Demore, W. B.

    1978-01-01

    Absorption cross-sections of hydrogen peroxide vapor and of neutral aqueous solutions of hydrogen peroxide were measured in the wavelength range from 195 to 350 nm at 296 K. The spectrophotometric procedure is described, and the reported cross-sections are compared with values obtained by other researchers. Photodissociation coefficients of atmospheric H2O2 were calculated for direct absorption of unscattered solar radiation, and the vertical distributions of these coefficients are shown for various solar zenith angles.

  10. Nickel-hydrogen cell reversal characteristics

    NASA Technical Reports Server (NTRS)

    Lurie, Charles

    1994-01-01

    Nickel-hydrogen cell reversal characteristics are being studied as part of a TRW program directed towards development of a high current battery cell bypass switch. The following are discussed: cell bypass switch; nickel-hydrogen cell reversal characteristics; and nickel-hydrogen cell chemistry: discharge/reversal and overdischarge (reversal) with nickel and hydrogen precharge.

  11. Optical Absorption Characteristics of Aerosols.

    DTIC Science & Technology

    1985-09-11

    properties of the powder as well as the thickness of the layer. For a layer that is thick enough so that no light is transmitted, the Kubelka -- Munk theory...which is a two stream radiative transfer model, relates the reflectance to the ratio of the absorption to the scattering. The Kubelka - Munk theory has...of the aerosol material is known. Under the assumptions of the Kubelka - Munk . theory, the imaginary component of the refractive index is deter- mined

  12. Microwave Absorption Characteristics of Tire

    NASA Astrophysics Data System (ADS)

    Zhang, Yuzhe; Hwang, Jiann-Yang; Peng, Zhiwei; Andriese, Matthew; Li, Bowen; Huang, Xiaodi; Wang, Xinli

    The recycling of waste tires has been a big environmental problem. About 280 million waste tires are produced annually in the United States and more than 2 billion tires are stockpiled, which cause fire hazards and health issues. Tire rubbers are insoluble elastic high polymer materials. They are not biodegradable and may take hundreds of years to decompose in the natural environment. Microwave irradiation can be a thermal processing method for the decomposition of tire rubbers. In this study, the microwave absorption properties of waste tire at various temperatures are characterized to determine the conditions favorable for the microwave heating of waste tires.

  13. Infrared absorption of hydrogen-related defects in ammonothermal GaN

    SciTech Connect

    Suihkonen, Sami; Pimputkar, Siddha; Speck, James S.; Nakamura, Shuji

    2016-05-16

    Polarization controlled Fourier transform infrared (FTIR) absorption measurements were performed on a high quality m-plane ammonothermal GaN crystal grown using basic chemistry. The polarization dependence of characteristic absorption peaks of hydrogen-related defects at 3000–3500 cm{sup −1} was used to identify and determine the bond orientation of hydrogenated defect complexes in the GaN lattice. Majority of hydrogen was found to be bonded in gallium vacancy complexes decorated with one to three hydrogen atoms (V{sub Ga}-H{sub 1,2,3}) but also hydrogenated oxygen defect complexes, hydrogen in bond-center sites, and lattice direction independent absorption were observed. Absorption peak intensity was used to determine a total hydrogenated V{sub Ga} density of approximately 4 × 10{sup 18} cm{sup −3}, with main contribution from V{sub Ga}-H{sub 1,2}. Also, a significant concentration of electrically passive V{sub Ga}-H{sub 3} was detected. The high density of hydrogenated defects is expected to have a strong effect on the structural, optical, and electrical properties of ammonothermal GaN crystals.

  14. Colonic hydrogen absorption: quantification of its effect on hydrogen accumulation caused by bacterial fermentation of carbohydrates.

    PubMed Central

    Hammer, H F

    1993-01-01

    The aim of the study was to assess (quantitatively) colonic hydrogen absorption. Hydrogen volumes in flatus and breath were measured over periods of six hours in normal subjects during fasting and after ingestion of the non-absorbable carbohydrate lactulose to simulate the effect of fermentable dietary fibres. If less than 76 ml/6 h of hydrogen accumulated in the colon then all of it was absorbed, as suggested by the intercept of the regression line of the correlation between hydrogen volumes in flatus and breath after ingestion of lactulose. As total flatus volume increased, efficiency of colonic hydrogen absorption decreased from 90% to 20%. The positive correlation between hydrogen volumes of flatus and breath showed that the eightfold interindividual differences in flatus volume after ingestion of 12.5 g of lactulose were caused by differences in bacterial net gas production, not gas absorption. Differences in colonic gas emptying rate are the consequence rather than the cause of interindividual differences in flatus volume. In conclusion: (1) colonic hydrogen absorption is highly effective at low colonic hydrogen accumulation rates, but not at higher accumulation rates; (2) ineffective colonic gas absorption is the consequence and not the cause of high colonic gas accumulation rate after ingestion of non-absorbable carbohydrates; and (3) future therapeutic approaches to the large interindividual variability in colonic gas accumulation after ingestion of poorly absorbable fermentable carbohydrates, such as some kinds of dietary fibres, should be directed towards altering colonic bacterial metabolism. PMID:8314516

  15. THE ABSORPTION OF HYDROGEN ON LOW PRESSURE HYDRIDE MATERIALS

    SciTech Connect

    Morgan, G.; Korinko, P.

    2012-04-03

    For this study, hydrogen getter materials (Zircaloy-4 and pure zirconium) that have a high affinity for hydrogen (and low overpressure) have been investigated to determine the hydrogen equilibrium pressure on Zircaloy-4 and pure zirconium. These materials, as with most getter materials, offered significant challenges to overcome given the low hydrogen equilibrium pressure for the temperature range of interest. Hydrogen-zirconium data exists for pure zirconium at 500 C and the corresponding hydrogen overpressure is roughly 0.01 torr. This manuscript presents the results of the equilibrium pressures for the absorption and desorption of hydrogen on zirconium materials at temperatures ranging from 400 C to 600 C. The equilibrium pressures in this temperature region range from 150 mtorr at 600 C to less than 0.1 mtorr at 400 C. It has been shown that the Zircaloy-4 and zirconium samples are extremely prone to surface oxidation prior to and during heating. This oxidation precludes the hydrogen uptake, and therefore samples must be heated under a minimum vacuum of 5 x 10{sup -6} torr. In addition, the Zircaloy-4 samples should be heated at a sufficiently low rate to maintain the system pressure below 0.5 mtorr since an increase in pressure above 0.5 mtorr could possibly hinder the H{sub 2} absorption kinetics due to surface contamination. The results of this study and the details of the testing protocol will be discussed.

  16. Ultraviolet absorption spectrum of hydrogen peroxide vapor. [for atmospheric abundances

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Schinke, S. D.; Molina, M. J.

    1977-01-01

    The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296 K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 x 10 to the -5th/sec.

  17. Ultraviolet absorption spectra of metalorganic molecules diluted in hydrogen gas

    NASA Astrophysics Data System (ADS)

    Itoh, Hideo; Watanabe, Masanobu; Mukai, Seiji; Yajima, Hiroyoshi

    1988-12-01

    Ultraviolet absorption spectra of trimethyl gallium, triethyl gallium, and trimethyl aluminum diluted in hydrogen gas were measured as a function of the wavelength (185-350 nm) and the concentration of the molecules (4.8×10 -6 -1.6×10 -4 mol/liter). Their absorbances changed linearly with the concentration of the molecules, which allowed us to calculate the molar absorption coefficients of the molecules on the basis of the Beer-Lambert law.

  18. Thermodynamic Evaluation of Hydrogen Absorption by Niobium During SRF Fabrication

    SciTech Connect

    Ricker, R. E.; Myneni, G. R.

    2011-03-31

    The properties and performance of the ultra high purity Nb used to fabricate superconducting radio frequency (SRF) particle accelerator cavities have been found to vary with processing conditions. One hypothesis for these variations is that hydrogen, absorbed during processing, is responsible for this behavior. The key assumption behind this hypothesis is that niobium can absorb hydrogen from one or more of the processing environments. This paper reviews work examining the validity of this assumption. It was determined that Nb will spontaneously react with water producing adsorbed atomic hydrogen that is readily absorbed into the metal. The passivating oxide film normally prevents this reaction, but this film is frequently removed during processing and it is attacked by the fluoride ion used in the polishing solutions for SRF cavities. However, during electropolishing that cathodic reduction of hydrogen is transferred to the auxiliary electrode and this should suppress hydrogen absorption.

  19. Thermodynamic Evaluation of Hydrogen Absorption by Niobium During SRF Fabrication

    SciTech Connect

    R.E. Ricker, G.R. Myneni

    2011-03-01

    The properties and performance of the ultra high purity Nb used to fabricate superconducting radio frequency (SRF) particle accelerator cavities have been found to vary with processing conditions. One hypothesis for these variations is that hydrogen, absorbed during processing, is responsible for this behavior. The key assumption behind this hypothesis is that niobium can absorb hydrogen from one or more of the processing environments. This paper reviews work examining the validity of this assumption. It was determined that Nb will spontaneously react with water producing adsorbed atomic hydrogen that is readily absorbed into the metal. The passivating oxide film normally prevents this reaction, but this film is frequently removed during processing and it is attacked by the fluoride ion used in the polishing solutions for SRF cavities. However, during electropolishing that cathodic reduction of hydrogen is transferred to the auxiliary electrode and this should suppress hydrogen absorption.

  20. RECTIFIED ABSORPTION METHOD FOR THE SEPARATION OF HYDROGEN ISOTOPES

    DOEpatents

    Hunt, C.D.; Hanson, D.N.

    1961-10-17

    A method is described for separating and recovering heavy hydrogen isotopes from gaseous mixtures by multiple stage cyclic absorption and rectification from an approximate solvent. In particular, it is useful for recovering such isoteoes from ammonia feedstock streams containing nitrogen solvent. Modifications of the process ranging from isobaric to isothermal are provided. Certain impurities are tolerated, giving advantages over conventional fractional distillation processes. (AEC)

  1. Surface Hydrogen and Subsurface Hydrogen: Their Roles in Bulk Absorption and Surface Reaction

    NASA Astrophysics Data System (ADS)

    Fukutani, Katsuyuki

    Hydrogen adsorbed on metal surfaces possibly penetrates into “subsurface” sites, which might further diffuse into bulk. When temperature is raised, on the other hand, such absorbed hydrogen diffuses back to the surface via the subsurface site eventually desorbing from the surface. The kinetics of these absorption and desorption are ideally expressed by the potential energy surfaces of hydrogen near the surfaces. This article describes how the potential of hydrogen is described, and how the surface and subsurface sites influence the kinetics of absorption and desorption for Pd and Ni as examples. As well as these phenomena, the subsurface sites could serve to promote particular hydrogenation reactions occurring at surfaces. The mechanism of subsurface chemistry is discussed.

  2. Hydrogen absorption-desorption properties of U 2Ti

    NASA Astrophysics Data System (ADS)

    Takuya, Yamamoto; Satoru, Tanaka; Michio, Yamawaki

    1990-02-01

    Hydrogen absorption-desorption properties of U 2Ti intermetallic compound was examined over the temperature range of 298 to 973 K and at hydrogen pressures below 10 5 Pa. It absorbs hydrogen up to 7.6 atoms per F.U. (formula unit) by two step reactions and hence each desorption isotherm is separated into two plateau regions. In the first plateau, a newly-found ternary hydride is formed, where the hydrogen concentration, cH, reaches 2.4 H atoms/F.U. In the second plateau, UH 3 is formed and cH reaches 7.6 H atoms/F.U. The specimen is disintegrated into fine powder in the second plateau, while in the first plateau the ternary hydride which was identified to be UTi 2H x, ( x = 4.8 to 6.2) showed high durability against powdering. It is predicted that UTi 2 can be suitable material for tritium storage.

  3. Active hydrogen excretion and sodium absorption through isolated frog skin.

    PubMed

    Ehrenfeld, J; Garcia-Romeu, F

    1977-07-01

    The in vitro skin of Rana esculenta was studied in open-circuit conditions. It was shown that when the external face is bathed in a 2-meq solution of NaCl, sodium is absorbed at a significantly higher rate than chloride. The ionic balance is maintained by excretion of hydrogen. With a mucosal solution of 2 meq Na2SO4 the equation relating sodium absorption to proton excretion is JnH+ = (-25 +/- 7) - (0.73 +/- 0.04) JnNa+. The correlation between the two variables is highly significant. Hydrogen excretion obeys saturation kinetics in relation to the sodium concentration of the mucosal solution. Maximum excretion occurs at a sodium concentration of 4 meq. When the mucosal solution is a 115-meq solution of Na2SO4 the net flux of sodium is 2.3 times higher than that of hydrogen. The balance is maintained by absorption of SO42-. The effects of various substances on the Na+ext/H+int exchange were studied. With a mucosal solution of 2 meq Na2SO4 and short-circuit conditions it was shown that the hydrogen excretion is active and nearly the same as in open circuit, the short-circuit current is equal (to within 8%) to the sum of the sodium and hydrogen net fluxes, and the correlation between the movements of the two ions is low. A model relating the active proton excretion with the sodium transport mechanism is proposed.

  4. Molecular absorption cryogenic cooler for liquid hydrogen propulsion systems

    NASA Technical Reports Server (NTRS)

    Klein, G. A.; Jones, J. A.

    1982-01-01

    A light weight, long life molecular absorption cryogenic cooler (MACC) system is described which can use low temperature waste heat to provide cooling for liquid hydrogen propellant tanks for interplanetary spacecraft. Detailed tradeoff studies were made to evaluate the refrigeration system component interactions in order to minimize the mass of the spacecraft cooler system. Based on this analysis a refrigerator system mass of 31 kg is required to provide the .48 watts of cooling required by a 2.3 meter diameter liquid hydrogen tank.

  5. LaNi5 Hydrogen-Absorption Cryogenic System

    NASA Technical Reports Server (NTRS)

    Jones, J. A.

    1986-01-01

    Hydrogen-absorption refrigerating system provides about 650 mW of cooling at 20 to 29 K in continuous, closed-cycle operation. Three thermally cycled absorbers/desorbers act as compressors. System successfully tested below 29 K for over 1,000 h, while separate room-temperature hydride compressor operated continuously for 6,000 h. Due to lack of moving parts, lifetimes of 10 years or more eventually expected.

  6. Mg/Ti multilayers: Structural and hydrogen absorption properties

    NASA Astrophysics Data System (ADS)

    Baldi, A.; Pálsson, G. K.; Gonzalez-Silveira, M.; Schreuders, H.; Slaman, M.; Rector, J. H.; Krishnan, G.; Kooi, B. J.; Walker, G. S.; Fay, M. W.; Hjörvarsson, B.; Wijngaarden, R. J.; Dam, B.; Griessen, R.

    2010-06-01

    Mg-Ti alloys have uncommon optical and hydrogen absorbing properties, originating from a “spinodal-like” microstructure with a small degree of chemical short-range order in the atomic distribution. In the present study we artificially engineer short-range order by depositing Pd-capped Mg/Ti multilayers with different periodicities. Notwithstanding the large lattice mismatch between Mg and Ti, the as-deposited metallic multilayers show good structural coherence. On exposure to H2 gas a two-step hydrogenation process occurs with the Ti layers forming the hydride before Mg. From in situ measurements of the bilayer thickness Λ at different hydrogen pressures, we observe large out-of-plane expansions of Mg and Ti layers on hydrogenation, indicating strong plastic deformations in the films and a consequent shortening of the coherence length. On unloading at room temperature in air, hydrogen atoms remain trapped in the Ti layers due to kinetic constraints. Such loading/unloading sequence can be explained in terms of the different thermodynamic properties of hydrogen in Mg and Ti, as shown by diffusion calculations on a model multilayered systems. Absorption isotherms measured by hydrogenography can be interpreted as a result of the elastic clamping arising from strongly bonded Mg/Pd and broken Mg/Ti interfaces.

  7. Nebular Hydrogen Absorption in the Ejecta of Eta Carinae

    NASA Technical Reports Server (NTRS)

    Gull, Theodore R.; Ishibashi, K.; Davidson, K.; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    Space Telescope Imaging Spectrograph (STIS) observations of Eta Carinae and immediate ejecta reveal narrow Balmer absorption lines in addition to the nebular-scattered broad P-Cygni absorptions. The narrow absorption correlates with apparent disk structure that separates the two Homunculus lobes. We trace these features about half way up the Northern lobe until the scattered stellar Balmer line doppler-shifts redward beyond the nebular absorption feature. Three-dimensional data cubes, made by mapping the Homunculus at Balmer alpha and Balmer beta with the 52 x 0.1 arcsecond aperture and about 5000 spectral resolving power, demonstrate that the absorption feature changes slowly in velocity with nebular position. We have monitored the stellar Balmer alpha line profile of the central source over the past four years. The equivalent width of the nebular absorption feature changes considerably between observations. The changes do not correlate with measured brightness of Eta Carinae. Likely clumps of neutral hydrogen with a scale size comparable to the stellar disk diameter are passing through the intervening light path on the timescales less than several months. The excitation mechanism involves Lyman alpha radiation (possibly the Lyman series plus Lyman continuum) and collisions leading to populating the 2S metastable state. Before the electron can jump to the ground state by two photon emission (lifetime about 1/8 second), a stellar Balmer photon is absorbed and the electron shifts to an NP level. We see the absorption feature in higher Balmer lines, and but not in Paschen lines. Indeed we see narrow nebular Paschen emission lines. At present, we do not completely understand the details of the absorption. Better understanding should lead to improved insight of the unique conditions around Eta Carinae that leads to these absorptions.

  8. Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles

    NASA Astrophysics Data System (ADS)

    Narayan, Tarun C.; Hayee, Fariah; Baldi, Andrea; Leen Koh, Ai; Sinclair, Robert; Dionne, Jennifer A.

    2017-01-01

    Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation--the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm--to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth of the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. The nanoparticles' ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.

  9. Hydrogenated blue titania with high solar absorption and greatly improved photocatalysis

    NASA Astrophysics Data System (ADS)

    Zhu, Guilian; Shan, Yufeng; Lin, Tianquan; Zhao, Wenli; Xu, Jijian; Tian, Zhangliu; Zhang, Hui; Zheng, Chong; Huang, Fuqiang

    2016-02-01

    Hydrogenated black titania, with a crystalline core/amorphous shell structure, has attracted global interest due to its excellent photocatalytic properties. However, the understanding of its structure-property relationships remains a great challenge and a more effective method to produce hydrogenated titania is desirable. Herein, we report a TiH2 assisted reduction method to synthesize bluish hydrogenated titania (TiO2-x:H) that is highly crystallized. The characteristic amorphous shells, which are essential for the enhancement of solar absorption and photocatalysis in many reported hydrogenated titania, are completely removed by hydrogen peroxide. The blue TiO2-x:H sample without amorphous shells delivers not only significantly improved visible- and infrared-light absorption but also greatly enhanced photocatalytic activity compared to pristine TiO2. Its water decontamination is 2.5 times faster and the hydrogen production was 1.9-fold higher over pristine TiO2. Photoelectrochemical measurement reveals greatly improved carrier density and photocurrent (a 4.3-fold increase) in the reduced TiO2-x:H samples. This work develops a facile and versatile method to prepare hydrogenated titania and proposes a new understanding of the hydrogenated titania that doped hydrogen atoms, instead of the amorphous shells, are essential for its high photocatalytic performance.Hydrogenated black titania, with a crystalline core/amorphous shell structure, has attracted global interest due to its excellent photocatalytic properties. However, the understanding of its structure-property relationships remains a great challenge and a more effective method to produce hydrogenated titania is desirable. Herein, we report a TiH2 assisted reduction method to synthesize bluish hydrogenated titania (TiO2-x:H) that is highly crystallized. The characteristic amorphous shells, which are essential for the enhancement of solar absorption and photocatalysis in many reported hydrogenated titania, are

  10. Transient absorption spectra of the laser-dressed hydrogen atom

    NASA Astrophysics Data System (ADS)

    Murakami, Mitsuko; Chu, Shih-I.

    2013-10-01

    We present a theoretical study of transient absorption spectra of laser-dressed hydrogen atoms, based on numerical solutions of the time-dependent Schrödinger equation. The timing of absorption is controlled by the delay between an extreme ultra violet (XUV) pulse and an infrared (IR) laser field. The XUV pulse is isolated and several hundred attoseconds in duration, which acts as a pump to drive the ground-state electron to excited p states. The subsequent interaction with the IR field produces dressed states, which manifest as sidebands between the 1s-np absorption spectra separated by one IR-photon energy. We demonstrate that the population of dressed states is maximized when the timing of the XUV pulse coincides with the zero crossing of the IR field, and that their energies can be manipulated in a subcycle time scale by adding a chirp to the IR field. An alternative perspective to the problem is to think of the XUV pulse as a probe to detect the dynamical ac Stark shifts. Our results indicate that the accidental degeneracy of the hydrogen excited states is removed while they are dressed by the IR field, leading to large ac Stark shifts. Furthermore, we observe the Autler-Townes doublets for the n=2 and 3 levels using the 656 nm dressing field, but their separation does not agree with the prediction by the conventional three-level model that neglects the dynamical ac Stark shifts.

  11. Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys

    NASA Astrophysics Data System (ADS)

    Urgnani, J.; Di Chio, M.; Palumbo, M.; Feuerbacher, M.; Fernandez, J. F.; Leardini, F.; Baricco, M.

    2009-01-01

    The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H2 absorption/desorption kinetics. In this paper, the interaction of H2 with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg38.5Al61.5, Mg69Al31 and Mg72Al28. For Mg72Al28, no significant changes in the microstructure have been obtained by rapid solidification. In Mg69Al31, a significant grain refinement has been observed, whereas, for Mg38.5Al61.5, the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H2 absorption, leading to MgH2. After heating up to 430 °C the hydrogenated samples, a main desorption reaction from MgH2 has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.

  12. Novel insight into the hydrogen absorption mechanism at the Pd(110) surface

    SciTech Connect

    Ohno, Satoshi E-mail: wilde@iis.u-tokyo.ac.jp; Wilde, Markus E-mail: wilde@iis.u-tokyo.ac.jp; Fukutani, Katsuyuki

    2014-04-07

    The microscopic mechanism of low-temperature (80 K < T < 160 K) hydrogen (H) ingress into the H{sub 2} (<2.66 × 10{sup −3} Pa) exposed Pd(110) surface is explored by H depth profiling with {sup 15}N nuclear reaction analysis (NRA) and thermal desorption spectroscopy (TDS) with isotope (H, D) labeled surface hydrogen. NRA and TDS reveal two types of absorbed hydrogen states of distinctly different depth distributions. Between 80 K and ∼145 K a near-surface hydride phase evolving as the TDS α{sub 1} feature at 160 K forms, which initially extends only several nanometers into depth. On the other hand, a bulk-absorbed hydrogen state develops between 80 K and ∼160 K which gives rise to a characteristic α{sub 3} TDS feature above 190 K. These two absorbed states are populated at spatially separated surface entrance channels. The near-surface hydride is populated through rapid penetration at minority sites (presumably defects) while the bulk-absorbed state forms at regular terraces with much lower probability per site. In both cases, absorption of gas phase hydrogen transfers pre-adsorbed hydrogen atoms below the surface and replaces them at the chemisorption sites by post-dosed hydrogen in a process that requires much less activation energy (<100 meV) than monatomic diffusion of chemisorbed H atoms into subsurface sites. This small energy barrier suggests that the rate-determining step of the absorption process is either H{sub 2} dissociation on the H-saturated Pd surface or a concerted penetration mechanism, where excess H atoms weakly bound to energetically less favorable adsorption sites stabilize themselves in the chemisorption wells while pre-chemisorbed H atoms simultaneously transit into the subsurface. The peculiarity of absorption at regular Pd(110) terraces in comparison to Pd(111) and Pd(100) is discussed.

  13. Gamma radiation induces hydrogen absorption by copper in water

    NASA Astrophysics Data System (ADS)

    Lousada, Cláudio M.; Soroka, Inna L.; Yagodzinskyy, Yuriy; Tarakina, Nadezda V.; Todoshchenko, Olga; Hänninen, Hannu; Korzhavyi, Pavel A.; Jonsson, Mats

    2016-04-01

    One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.

  14. Gamma radiation induces hydrogen absorption by copper in water

    PubMed Central

    Lousada, Cláudio M.; Soroka, Inna L.; Yagodzinskyy, Yuriy; Tarakina, Nadezda V.; Todoshchenko, Olga; Hänninen, Hannu; Korzhavyi, Pavel A.; Jonsson, Mats

    2016-01-01

    One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories. PMID:27086752

  15. Gamma radiation induces hydrogen absorption by copper in water.

    PubMed

    Lousada, Cláudio M; Soroka, Inna L; Yagodzinskyy, Yuriy; Tarakina, Nadezda V; Todoshchenko, Olga; Hänninen, Hannu; Korzhavyi, Pavel A; Jonsson, Mats

    2016-04-18

    One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.

  16. Spectroscopic study of low-temperature hydrogen absorption in palladium

    SciTech Connect

    Ienaga, K. Takata, H.; Onishi, Y.; Inagaki, Y.; Kawae, T.; Tsujii, H.; Kimura, T.

    2015-01-12

    We report real-time detection of hydrogen (H) absorption in metallic palladium (Pd) nano-contacts immersed in liquid H{sub 2} using inelastic electron spectroscopy (IES). After introduction of liquid H{sub 2}, the spectra exhibit the time evolution from the pure Pd to the Pd hydride, indicating that H atoms are absorbed in Pd nano-contacts even at the temperature where the thermal process is not expected. The IES time and bias voltage dependences show that H absorption develops by applying bias voltage 30 ∼ 50 mV, which can be explained by quantum tunneling. The results represent that IES is a powerful method to study the kinetics of high density H on solid surface.

  17. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Wine, P. H.

    1988-01-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  18. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    NASA Astrophysics Data System (ADS)

    Nicovich, J. M.; Wine, P. H.

    1988-03-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  19. Absorption characteristics of forest fire particulate matter

    Treesearch

    E.M. Patterson; Charles K. McMahon

    1984-01-01

    Abstract. Absorption properties of smokes from laboratory fires that represent prescription hums in the Southern states have been quantified to relate variations in measured absorption parameters to variation in fire conditions and to estimate emission factors for elemental carbon. Results showed significant differences in absorption of the smoke...

  20. Hydrogen Absorption in Pd-based Nanostructures - Final Report

    SciTech Connect

    David Lederman

    2012-10-22

    Pd is known to absorb hydrogen. Molecules are normally chemisorbed at the surface in a process where the molecule breaks into two hydrogen atoms, and the protons are then absorbed into the bulk. This process consists of electron filling holes in the Pd 4d band near the Fermi energy, which due to the high density of states at the Fermi energy, is an energetically favorable process. Our aim with this project was to determine possible changes in magnetic properties with Pd nm-length-scale thick layers intercalated by magnetic materials. Before the start of this work, the literature indicated that there were several possible scenarios by which this could happen: i) the Pd will be magnetized due to a proximity effect with nearby magnetic layers, resulting in changes in the magnetization due to H2 absorption; ii) some H will be absorbed into the magnetic layers, causing a change in the magnetic exchange interactions; or iii) absorption of H2 will cause an expansion of the lattice, resulting in a magnetoelastic effect which changes the magnetic properties.

  1. Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles

    DOE PAGES

    Narayan, Tarun C.; Hayee, Fariah; Baldi, Andrea; ...

    2017-01-16

    Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation—the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm—to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth ofmore » the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. As a result, the nanoparticles’ ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.« less

  2. Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles

    PubMed Central

    Narayan, Tarun C.; Hayee, Fariah; Baldi, Andrea; Leen Koh, Ai; Sinclair, Robert; Dionne, Jennifer A.

    2017-01-01

    Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation—the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm—to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth of the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. The nanoparticles' ability to remove crystallographic imperfections renders them more durable than their bulk counterparts. PMID:28091597

  3. Thermoluminescence characteristics of hydrogenated amorphous zirconia

    NASA Astrophysics Data System (ADS)

    Montalvo, T. R.; Tenorio, L. O.; Nieto, J. A.; Salgado, M. B.; Estrada, A. M. S.; Furetta, C.

    2005-05-01

    This paper reports the experimental results concerning the thermoluminescent (TL) characteristics of hydrogenated amorphous zirconium oxide (a-Zr:H) powder prepared by the sol-gel method. The advantages of this method are the homogeneity and the purity of the gels associated with a relatively low sintering temperature. Hydrogenated amorphous powder was characterized by thermal analysis and X-ray diffraction. The main TL characteristics investigated were the TL response as a function of the absorbed dose, the reproducibility of the TL readings and the fading. The undoped a-Zr:H powder presents a TL glow curve with two peaks centered at 150 and 260 degrees C, respectively, after beta irradiation. The TL response a-Zr:H as a function of the absorbed dose showed a linear behavior over a wide range. The results presented open the possibility to use this material as a good TL dosimeter.

  4. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    SciTech Connect

    Nakano, H. Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-04-08

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure.

  5. Temperature-pressure characteristics of SMH actuator system using hydrogen-absorbing alloys

    NASA Astrophysics Data System (ADS)

    Kim, Kyung; Ryu, Mun-Ho; Kim, Dong-Wook; Kwon, Tae-Kyu; Lee, Seong-Chul; Kim, Nam-Gyun

    2009-03-01

    This paper presents the temperature-pressure characteristics of a newly developed SMH actuator using hydrogen-absorbing alloys. The new special metal hydride(SMH) actuator is characterized by its small size, low weight, noiseless operation, and compliance similar to that of human bodies. The simple SMH actuator, consisting of plated hydrogen-absorbing alloys as a power source, Peltier modules as a thermal source, and a cylinder with metal bellows as a mechanical functioning part, has been developed. An assembly of copper pipes has been constructed to improve the thermal conductivity of the hydrogen-absorbing alloys. It is well known that hydrogen-absorbing alloys can reversibly absorb and desorb a large amount of hydrogen, more than about one thousand times of their own volume. By heating the hydrogen-absorbing alloys, the hydrogen equilibrium pressure increases due to desorption of hydrogen, whereas, by cooling the alloys, the hydrogen equilibrium pressure drops due to absorption of hydrogen by the alloys. The new SMH actuator utilizes the reversible reaction between the thermal energy and mechanical energy of the hydrogen absorbing alloys. To be able to use the SMH actuator in medical and rehabilitation applications, the desirable characteristics of the actuator have been studied. For this purpose, the detailed characteristics of the new SMH actuator for different temperature, pressure, and external loads were explored.

  6. Collision-induced vibrational absorption in molecular hydrogens

    SciTech Connect

    Reddy, S.P.

    1993-05-01

    Collision induced absorption (CIA) spectra of the first overtone bands of H{sub 2}, D{sub 2}, and HD have been recorded for gas densities up to 500 amagat at 77-300 K. Analyses of these spectra reveal that (1) contrary to the observations in the fundamental bands, the contribution of the isotropic overlap interaction to the first overtone bands is negligible, (2) the squares of the matrix elements B{sub 32}(R)/ea{sub o} [= {lambda}{sub 32} exp(-(R-{sigma})/{rho}{sub 32}) + 3 (R/a{sub o}){sup -4}] where the subscripts 3 and 2 represent L and {lambda}, respectively, account for the absorption intensity of the bands and (3) the mixed term, 2,3 {lambda}{sub 32} exp (-(R-{sigma})/{rho}{sub 32}) <{vert_bar}Q{vert_bar}> <{alpha}> (R/a){sup -4}, gives a negative contribution. In the CIA spectra of H{sub 2} in its second overtone region recorded at 77, 201 and 298 K for gas densities up to 1000 amagat, a dip in the Q branch with characteristic Q{sub p} and Q{sub R} components has been observed. The analysis of the absorption profiles reveals, in addition to the previously known effects, the occurrence of the triple-collision transitions of H{sub 2} of the type Q{sub 1}(J) + Q{sub 1}(J) + Q{sub 1}(J) for the first time. From the profile analysis the absorption coefficient of these transitions is obtained.

  7. Use of underpotential deposition of zinc to mitigate hydrogen absorption into Monel K500

    SciTech Connect

    Zheng, G.; Popov, B.N.; White, R.E. . Dept. of Chemical Engineering)

    1994-05-01

    Polarization experiments and a potentiostatic pulse technique have been used to show that a monolayer coverage of zinc effectively inhibits the absorption of hydrogen into Monel K500. By depositing a monolayer of zinc on Monel K500 the hydrogen, evolution reaction and hydrogen ingress flux rate were reduced by 60%.

  8. Performance Characteristics of Absorption Hybrid Cycle Introduced Compressor

    NASA Astrophysics Data System (ADS)

    Iyoki, Shigeki; Kotani, Yuji; Uemura, Tadashi

    In this paper, four kinds of absorption hybrid cycle which introduced the compressor in the absorption cycle were proposed. As basic cycle of absorption refrigerating machine, the following were chosen: two kinds of single-stage absorption refrigerating machine and two kinds of double effect absorption refrigerating machine. As a working medium-absorbent system, NH3-H2O system, C2H5NH2-H2O system and C2H5NH2-H2O-LiBr system were adopted. Using these three kinds of working medium-absorbent system, the performance characteristics of four kinds of absorption hybrid cycle were simulated. And the performance characteristics of these cycles were compared.

  9. Hydrogen Absorption into Austenitic Stainless Steels Under High-Pressure Gaseous Hydrogen and Cathodic Charge in Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Enomoto, Masato; Cheng, Lin; Mizuno, Hiroyuki; Watanabe, Yoshinori; Omura, Tomohiko; Sakai, Jun'ichi; Yokoyama, Ken'ichi; Suzuki, Hiroshi; Okuma, Ryuji

    2014-12-01

    Type 316L and Type 304 austenitic stainless steels, both deformed and non-deformed, were hydrogen charged cathodically in an aqueous solution as well as by exposure to high-pressure gaseous hydrogen in an attempt to identify suitable conditions of cathodic charge for simulating hydrogen absorption from gaseous hydrogen environments. Thermal desorption analysis (TDA) was conducted, and the amount of absorbed hydrogen and the spectrum shape were compared between the two charging methods. Simulations were performed by means of the McNabb-Foster model to analyze the spectrum shape and peak temperature, and understand the effects of deformation on the spectra. It was revealed that the spectrum shape and peak temperature were dependent directly upon the initial distribution of hydrogen within the specimen, which varied widely according to the hydrogen charge condition. Deformation also had a marked effect on the amount of absorbed hydrogen in Type 304 steel due to the strain-induced martensitic transformation.

  10. OPTICAL HYDROGEN ABSORPTION CONSISTENT WITH A THIN BOW SHOCK LEADING THE HOT JUPITER HD 189733B

    SciTech Connect

    Cauley, P. Wilson; Redfield, Seth; Jensen, Adam G.; Barman, Travis; Endl, Michael; Cochran, William D.

    2015-09-01

    Bow shocks are ubiquitous astrophysical phenomena resulting from the supersonic passage of an object through a gas. Recently, pre-transit absorption in UV metal transitions of the hot Jupiter (HJ) exoplanets HD 189733b and WASP12-b have been interpreted as being caused by material compressed in a planetary bow shock. Here we present a robust detection of a time-resolved pre-transit, as well as in-transit absorption signature around the HJ exoplanet HD 189733b using high spectral resolution observations of several hydrogen Balmer lines. The line shape of the pre-transit feature and the shape of the timeseries absorption provide the strongest constraints on the morphology and physical characteristics of extended structures around an exoplanet. The in-transit measurements confirm the previous exospheric Hα detection, although the absorption depth measured here is ∼50% lower. The pre-transit absorption feature occurs 125 minutes before the predicted optical transit, a projected linear distance from the planet to the stellar disk of 7.2 R{sub p}. The absorption strength observed in the Balmer lines indicates an optically thick, but physically small, geometry. We model this signal as the early ingress of a planetary bow shock. If the bow shock is mediated by a planetary magnetosphere, the large standoff distance derived from the model suggests a large planetary magnetic field strength of B{sub eq} = 28 G. Better knowledge of exoplanet magnetic field strengths is crucial to understanding the role these fields play in planetary evolution and the potential development of life on planets in the habitable zone.

  11. Effects of SWNT and metallic catalyst on hydrogen absorption/desorption performance of MgH2.

    PubMed

    Wu, Chengzhang; Wang, Ping; Yao, Xiangdong; Liu, Chang; Chen, Demin; Lu, Gao Qing; Cheng, Huiming

    2005-12-01

    The microstructure and absorption/desorption characteristics of composite MgH2 and 5 wt % as-prepared single-walled carbon nanotubes (MgH2-5ap) obtained by the mechanical grinding method were investigated. Experimental results show that the MgH2-5ap sample exhibits faster absorption kinetics and relatively lower desorption temperature than pure MgH2 or MgH2-purified single-walled carbon nanotube composite. Storage capacities of 6.0 and 4.2 wt % hydrogen for the MgH2-5ap composite were achieved in 60 min at 423 and 373 K, respectively. Furthermore, its desorption temperature was reduced by 70 K due to the introduction of as-prepared single-walled carbon nanotubes (SWNTs). In addition, the different effects of SWNTs and metallic catalysts contained in the as-prepared SWNTs were also investigated and a hydrogenation mechanism was proposed. It is suggested that metallic particles may be mainly responsible for the improvement of the hydrogen absorption kinetics, and SWNTs for the enhancement of hydrogen absorption capacity of MgH2.

  12. Hydrogen sorption characteristics of nanostructured Pd–10Rh processed by cryomilling

    DOE PAGES

    Yang, Nancy; Yee, Joshua K.; Zhang, Zhihui; ...

    2014-10-03

    Palladium and its alloys are model systems for studying solid-state storage of hydrogen. Mechanical milling is commonly used to process complex powder systems for solid-state hydrogen storage; however, milling can also be used to evolve nanostructured powder to modify hydrogen sorption characteristics. In the present study, cryomilling (mechanical attrition milling in a cryogenic liquid) is used to produce nanostructured palladium-rhodium alloy powder. Characterization of the cryomilled Pd-10Rh using electron microscopy, X-ray diffraction, and surface area analysis reveals that (i) particle morphology evolves from spherical to flattened disk-like particles; while the (ii) crystallite size decreases from several microns to less thanmore » 100 nm and (iii) dislocation density increases with increased cryomilling time. Hydrogen absorption and desorption isotherms as well as the time scales for absorption were measured for cryomilled Pd-10Rh, and correlated with observed microstructural changes induced by the cryomilling process. In short, as the microstructure of the Pd-10Rh alloy is refined by cryomilling: (i) the maximum hydrogen concentration in the α-phase increases, (ii) the pressure plateau becomes flatter, and (iii) the equilibrium hydrogen capacity at 760 Torr increases. In addition, the rate of hydrogen absorption was reduced by an order of magnitude compared to non-cryomilled (atomized) powder.« less

  13. Hydrogen sorption characteristics of nanostructured Pd–10Rh processed by cryomilling

    SciTech Connect

    Yang, Nancy; Yee, Joshua K.; Zhang, Zhihui; Kurmanaeva, Lilia; Cappillino, Patrick; Stavila, Vitalie; Lavernia, Enrique J.; San Marchi, Chris

    2014-10-03

    Palladium and its alloys are model systems for studying solid-state storage of hydrogen. Mechanical milling is commonly used to process complex powder systems for solid-state hydrogen storage; however, milling can also be used to evolve nanostructured powder to modify hydrogen sorption characteristics. In the present study, cryomilling (mechanical attrition milling in a cryogenic liquid) is used to produce nanostructured palladium-rhodium alloy powder. Characterization of the cryomilled Pd-10Rh using electron microscopy, X-ray diffraction, and surface area analysis reveals that (i) particle morphology evolves from spherical to flattened disk-like particles; while the (ii) crystallite size decreases from several microns to less than 100 nm and (iii) dislocation density increases with increased cryomilling time. Hydrogen absorption and desorption isotherms as well as the time scales for absorption were measured for cryomilled Pd-10Rh, and correlated with observed microstructural changes induced by the cryomilling process. In short, as the microstructure of the Pd-10Rh alloy is refined by cryomilling: (i) the maximum hydrogen concentration in the α-phase increases, (ii) the pressure plateau becomes flatter, and (iii) the equilibrium hydrogen capacity at 760 Torr increases. In addition, the rate of hydrogen absorption was reduced by an order of magnitude compared to non-cryomilled (atomized) powder.

  14. Investigation on the Hydrogen Gas Sensor Based on Exothermicity Reaction by Hydrogen Absorption into the Pd Film

    NASA Astrophysics Data System (ADS)

    Takashima, Noriaki; Kimura, Mitsuteru

    We have proposed a novel micro-calorimetric hydrogen sensor based on the temperature difference detection due to the exothermic reaction caused by hydrogen absorption in the palladium (Pd) thin film as a hydrogen absorbing material, and demonstrated using the prototype hydrogen sensor with a microheater and a pair of cantilever SOI thermocouples that this H2 sensor by this proposed mechanism is surely possible. We have ascertained that the sensor output voltage is increased as the H2 concentration is increased, that the exothermic reaction ceases after finish of the hydrogen absorption, the exothermic reaction by hydrogen absorption occurs even in pure N2 gas, that larger output voltage is observed for lower ambient temperature even under no oxygen gas, and that this hydrogen sensor does not respond to the CH4 gas. We have found that the detection of H2 concentration based on the exothermic reaction is preferred to carried out after heating the sensing region rather than during heating it especially in lower H2 concentration than about 5 vol.%, because we can use the null method to detect the extremely low H2 concentration.

  15. Hydrogen absorption in solid aluminum during high-temperature steam oxidation

    NASA Technical Reports Server (NTRS)

    Andreev, L. A.; Gelman, B. G.; Zhukhovitskiy, A. A.

    1979-01-01

    Hydrogen is emitted by aluminum heated in a vacuum after high-temperature steam treatment. Wire samples are tested for this effect, showing dependence on surface area. Two different mechanisms of absorption are inferred, and reactions deduced.

  16. Neutral hydrogen self-absorption in the Milky Way Galaxy

    NASA Astrophysics Data System (ADS)

    Kavars, Dain William

    2006-06-01

    To develop a better understanding of the cold neutral medium phase of the interstellar medium, we present a detailed analysis of neutral hydrogen self- absorption (HISA) clouds in the Milky Way Galaxy. These HISA clouds are in the Southern Galactic Plane Survey (SGPS), spanning the region l = 253°--358° and | b | <= 1.3°, and in the VLA Galactic Plane Survey (VGPS), spanning the region l = 18°--67° and | b | <= 1.3°--2.3°. The SGPS and VGPS have an angular resolution of ~1 arcminute and a velocity channel spacing of 0.82 km s -1 . With the recent completion of these surveys, we can study HISA features across the Galaxy at a much better resolution and sensitivity than any previous work. To analyze HISA in detail, catalogs of clouds of all sizes, including those undetectable by eye alone, are required. We present an automated search routine to detect all HISA clouds in the SGPS. We compare HISA to CO data and find some HISA clouds associated with CO, but others have no associated CO. This suggests that HISA clouds are in a transition between molecular and atomic gas, bridging the gap between dense molecular clouds and warmer, diffuse atomic clouds. HISA thus plays an important role in the overall evolution of the Galaxy. To study this transition further, we present observations of the OH molecule toward a select sample of HISA clouds in the VGPS, using the Green Bank Telescope (GBT). We present an analysis of the molecular properties of this sample, including a derivation of an OH to H 2 conversion factor and H 2 to H I abundance ratios. We discuss the complex relationship between H I, OH, 12 CO, and 13 CO emission. Finally we present a statistical analysis comparing HISA with infrared data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) project. The GLIMPSE data reveal a large number of compact, dark infrared clouds believed to be in the early stages of star formation. If GLIMPSE clouds are associated with HISA, they provide

  17. Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

    SciTech Connect

    Elliott, Drew; Scime, Earl; Short, Zachary

    2016-11-15

    Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

  18. Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

    NASA Astrophysics Data System (ADS)

    Elliott, Drew; Scime, Earl; Short, Zachary

    2016-11-01

    Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

  19. The use of infrared absorption to determine density of liquid hydrogen.

    NASA Technical Reports Server (NTRS)

    Unland, H. D.; Timmerhaus, K. D.; Kropschot, R. H.

    1972-01-01

    Experimental evaluation of the use of infrared absorption for determining the density of liquid hydrogen, and discussion of the feasibility of an airborne densitometer based on this concept. The results indicate that infrared absorption of liquid hydrogen is highly sensitive to the density of hydrogen, and, under the operating limitations of the equipment and experimental techniques used, the determined values proved to be repeatable to an accuracy of 2.7%. The desiderata and limitations of an in-flight density-determining device are outlined, and some of the feasibility problems are defined.

  20. Electronic absorption spectra of hydrogenated protonated naphthalene and proflavine

    NASA Astrophysics Data System (ADS)

    Bonaca, A.; Bilalbegović, G.

    2011-09-01

    We study hydrogenated cations of two polycyclic hydrocarbon molecules as models of hydrogenated organic species that form in the interstellar medium. Optical spectra of the hydrogenated naphthalene cation Hn-C10H+8 for n= 1, 2 and 10, as well as the astrobiologically interesting hydrogenated proflavine cation Hn-C13H11N+3 for n= 1 and 14, are calculated. The pseudopotential time-dependent density functional theory is used. It is found that the fully hydrogenated proflavine cation H14-C13H11N+3 shows a broad spectrum in which the positions of individual lines are almost lost. The positions, shapes and intensities of lines change in hydronaphthalene and hydroproflavine cations, showing that hydrogen additions induce substantially different optical spectra in comparison with base polycyclic hydrocarbon cations. One calculated line in the visible spectrum of H10-C10H+8 and one in the visible spectrum of H-C13H11N+3 are close to the measured diffuse interstellar bands. We also present the positions of near-ultraviolet lines.

  1. Infrared absorption on a complex comprising three equivalent hydrogen atoms in ZnO

    NASA Astrophysics Data System (ADS)

    Herklotz, F.; Hupfer, A.; Johansen, K. M.; Svensson, B. G.; Koch, S. G.; Lavrov, E. V.

    2015-10-01

    A hydrogen-related defect in ZnO which causes two broad IR absorption bands at 3303 and 3321 cm-1 is studied by means of infrared absorption spectroscopy and first-principles theory. In deuterated samples, the defect reveals two sharp absorption lines at 2466 and 2488 cm-1 accompanied by weaker sidebands at 2462 and 2480 cm-1. Isotope substitution experiments with varying concentrations of H and D together with polarization-sensitive measurements strongly suggest that these IR absorption lines are due to stretch local vibrational modes of a defect comprising three equivalent hydrogen atoms. The zinc vacancy decorated by three hydrogen atoms, VZnH3 , and ammonia trapped at the zinc vacancy, (NH3)Zn, are discussed as a possible origin for the complex.

  2. Change in soft magnetic properties of Fe-based metallic glasses during hydrogen absorption and desorption

    SciTech Connect

    Novak, L.; Lovas, A.; Kiss, L.F.

    2005-08-15

    The stress level can be altered in soft magnetic amorphous alloys by hydrogen absorption. The resulting changes in the soft magnetic parameters are reversible or irreversible, depending on the chemical composition. Some of these effects are demonstrated in Fe-B, Fe-W-B, and Fe-V-B glassy ribbons, in which various magnetic parameters are measured mainly during hydrogen desorption. The rate of hydrogen desorption is also monitored by measuring the pressure change in a hermetically closed bomb. The observed phenomena are interpreted on the basis of induced stresses and chemical interactions between the solute metal and hydrogen.

  3. Hydrogen Balmer Series Self-Absorption Measurement in Laser-Induced Air Plasma

    NASA Astrophysics Data System (ADS)

    Gautam, Ghaneshwar; Parigger, Christian

    2015-05-01

    In experimental studies of laser-induced plasma, we use focused Nd:YAG laser radiation to generate optical breakdown in laboratory air. A Czerny-Turner type spectrometer and an ICCD camera are utilized to record spatially and temporally resolved spectra. Time-resolved spectroscopy methods are employed to record plasma dynamics for various time delays in the range of 0.300 microsecond to typically 10 microsecond after plasma initiation. Early plasma emission spectra reveal hydrogen alpha and ionized nitrogen lines for time delays larger than 0.3 microsecond, the hydrogen beta line emerges from the free-electron background radiation later in the plasma decay for time delays in excess of 1 microsecond. The self-absorption analyses include comparisons of recorded data without and with the use of a doubling mirror. The extent of self-absorption of the hydrogen Balmer series is investigated for various time delays from plasma generation. There are indications of self-absorption of hydrogen alpha by comparison with ionized nitrogen lines at a time delay of 0.3 microsecond. For subsequent time delays, self-absorption effects on line-widths are hardly noticeable, despite the fact of the apparent line-shape distortions. Of interest are comparisons of inferred electron densities from hydrogen alpha and hydrogen beta lines as the plasma decays, including assessments of spatial variation of electron density.

  4. Exploring the hydrogen absorption into Pd-Ir nanoalloys supported on carbon

    NASA Astrophysics Data System (ADS)

    Malouche, Abdelmalek; Oumellal, Yassine; Ghimbeu, Camelia Matei; de Yuso, Alicia Martínez; Zlotea, Claudia

    2017-08-01

    Comprehensive understanding of the hydrogen gas interaction with metal nanoparticles is crucial for the development of multifunctional materials. The hydrogen absorption properties of well-dispersed Pd-Ir nanoalloys on a mesoporous carbon are reported here. The average size of nanoalloys depends on the composition and is comprised between 2.7 and 3.5 nm with decreasing Ir content. Structural analysis evidences a single phase FCC structure for all nanoparticles and a linear variation of the lattice parameter with composition confirming the formation of nanoalloys in this bulk-immiscible system. The hydrogen absorption properties can be tuned by the chemical composition: Pd-rich nanoparticles form hydride phases, whereas Ir-rich phases do not absorb hydrogen under ambient temperature and pressure conditions. The thermodynamic properties of hydride formation in Pd-rich phases are altered relative to the bulk counterparts. Moreover, the hydrogen absorption capacity in Pd-rich nanoalloys is larger as compared to bulk alloys. This might be explained by an important finite size effect that increases the hydrogen absorption capability of Pd-Ir alloys at nanoscale.

  5. Absorption of infrared radiation by electrons in the field of a neutral hydrogen atom

    NASA Technical Reports Server (NTRS)

    Stallcop, J. R.

    1974-01-01

    An analytical expression for the absorption coefficient is developed from a relationship between the cross-section for inverse bremsstrahlung absorption and the cross-section for electron-atom momentum transfer; it is accurate for those photon frequencies v and temperatures such that hv/kT is small. The determination of the absorption of infrared radiation by free-free transitions of the negative hydrogen ion has been extended to higher temperatures. A simple analytical expression for the absorption coefficient has been derived.

  6. Absorption of infrared radiation by electrons in the field of a neutral hydrogen atom

    NASA Technical Reports Server (NTRS)

    Stallcop, J. R.

    1974-01-01

    An analytical expression for the absorption coefficient is developed from a relationship between the cross-section for inverse bremsstrahlung absorption and the cross-section for electron-atom momentum transfer; it is accurate for those photon frequencies v and temperatures such that hv/kT is small. The determination of the absorption of infrared radiation by free-free transitions of the negative hydrogen ion has been extended to higher temperatures. A simple analytical expression for the absorption coefficient has been derived.

  7. Performance Characteristics of Hybrid Cycle Combined Absorption Heat Transformer and Absorption Refrigerating Machine

    NASA Astrophysics Data System (ADS)

    Iyoki, Shigeki; Otsuka, Shin-Ichi; Uemura, Tadashi

    In this paper, four kinds of hybrid cycles which combined the single-stage absorption refrigerating machine and four kinds of absorption heat transformers were proposed. It is possible that each of these hybrid cycles gets high temperature and low temperature from one cycle, simultaneously. As basic cycle of absorption heat transformer, the following were chosen: two kinds of single-stage absorption heat transformer and two kinds of two-stage absorption heat transformer. As a working medium-absorbent system, H2O-LiBr system, H2O-LiBr-LiNO3 system, H2O-LiBr-LiNO3-LiCl system, H2O-LiBr-C2H6O2 system and H2O-LiNO3-LiCl system were adopted. Using these five kinds of working medium-absorbent system, the performance characteristics of four kinds of hybrid cycle were simulated. And the performance characteristics of these cycles were compared.

  8. Infrared absorption cross sections of propane broadened by hydrogen

    NASA Astrophysics Data System (ADS)

    Wong, A.; Hargreaves, R. J.; Billinghurst, B.; Bernath, P. F.

    2017-09-01

    Fourier transform infrared absorption cross-sections of pure propane (C3H8) and propane broadened with H2 have been calculated from transmittance spectra recorded at temperatures from 292 K to 205 K. Transmittance spectra were recorded at the Canadian Light Source (CLS) Far-Infrared beamline, utilizing both the synchrotron source and the internal glowbar source. The absorption cross-sections have been calibrated to Pacific Northwest National Laboratory (PNNL) reference cross-sections of propane and can be used to interpret astronomical observations of giant planets such as Jupiter and Saturn as well as exoplanets.

  9. Molecular hydrogen ion /H2+/ absorption in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Feibelman, W. A.; Boggess, A.; Mccracken, C. W.; Hobbs, R. W.

    1981-01-01

    Several IUE spectra of planetary nebulae show an absorption feature shortward of 1500 A which is believed to be due to H2(+). The nebulae are excited by stars of spectral type O3-O7 or continuum, and all but one have double-shell structure.

  10. Hydrogen Absorption Property of Encapsulated Lani4.25A10.75

    SciTech Connect

    Heung, L.K.

    2003-07-21

    For hydrogen economy to become a reality, hydrogen production will have to be greatly increased from what it is today. Hydrogen will have to be recovered from a variety of gas streams including low concentration streams with efficient methods. Efficient process for recovering hydrogen in low concentration streams is not available today. Powder of LaNi4.25Al0.75 was encapsulated in a porous silica matrix to produce a stable composite material. The material was packed in a column and tested for hydrogen absorption from streams containing nitrogen, methane or carbon monoxide. The composite material removed hydrogen from nitrogen containing methane very well, but suffered decrease in capacity and rate when carbon monoxide was present. Using fluorinated metal hydride powder improved the kinetics but not the tolerance to carbon monoxide.

  11. Inhibition of Hydrogen Absorption in Pd by the Formation of a Pd-Ru Surface Alloy

    NASA Astrophysics Data System (ADS)

    Cabrera, A. L.; Ferrari, P.; Rojas, S.; Diaz-Droguett, Donovan; Ramos-Moore, E.; Laboratorio Ciencia de Materiales Team

    2013-03-01

    Hydrogen absorption by palladium has been studied for decades due to the significant importance in a number of applications like production and storage of hydrogen and hydrogen sensors. Alloying Pd with just a 4% of Ru drastically reduces the absorption properties of the Pd. The fcc crystal structure is preserved but the lattice constant is reduced slightly. In order to understand this phenomenon, we used three samples: a Pd foil, a Pd-Ru(4%) alloy foil, and a Pd foil with a Pd-Ru surface alloy. The surface alloy was made evaporating 8 nm of Ru using an e-beam evaporation technique on top of Pd, followed with a heating the sample up to 700 °C in a high vacuum system. We studied the changes in absorption properties of these samples using Thermal Program Desorption (TPD), resistance changes and grazing incidence X-ray Diffraction (GID). Funds from VRI-Puente 10/2012

  12. Hydrogen absorption by Zr-1Nb alloy with TiNx film deposited by filtered cathodic vacuum arc

    NASA Astrophysics Data System (ADS)

    Kashkarov, E. B.; Nikitenkov, N. N.; Syrtanov, M. S.; Babihina, M. N.

    2016-02-01

    coating for Zr-2.5Nb alloy from hydrogenation. Dense TiNx films were prepared by filtered cathodic vacuum arc (CVA). Hydrogen absorption rate was calculated from the kinetic curves of hydrogen sorption at elevated temperature of the sample (T = 673 K) and pressure (P = 2 atm). Results revealed that TiNx films significantly reduced hydrogen absorption rate of Zr-2.5Nb.

  13. Dynamic energy absorption characteristics of hollow microlattice structures

    SciTech Connect

    Liu, YL; Schaedler, TA; Chen, X

    2014-10-01

    Hollow microlattice structures are promising candidates for advanced energy absorption and their characteristics under dynamic crushing are explored. The energy absorption can be significantly enhanced by inertial stabilization, shock wave effect and strain rate hardening effect. In this paper we combine theoretical analysis and comprehensive finite element method simulation to decouple the three effects, and then obtain a simple model to predict the overall dynamic effects of hollow microlattice structures. Inertial stabilization originates from the suppression of sudden crushing of the microlattice and its contribution scales with the crushing speed, v. Shock wave effect comes from the discontinuity across the plastic shock wave front during dynamic loading and its contribution scales with e. The strain rate effect increases the effective yield strength upon dynamic deformation and increases the energy absorption density. A mechanism map is established that illustrates the dominance of these three dynamic effects at a range of crushing speeds. Compared with quasi-static loading, the energy absorption capacity a dynamic loading of 250 m/s can be enhanced by an order of magnitude. The study may shed useful insight on designing and optimizing the energy absorption performance of hollow microlattice structures under various dynamic loads. (C) 2014 Elsevier Ltd. All rights reserved.

  14. A survey of local interstellar hydrogen from OAO-2 observations of Lyman alpha absorption

    NASA Technical Reports Server (NTRS)

    Savage, B. D.; Jenkins, E. B.

    1972-01-01

    The Wisconsin far ultraviolet spectrometer aboard OAO-2 observed the wavelength region near 1216 A for 69 stars of spectral type B2 or earlier. From the strength of the observed interstellar L sub alpha absorption, atomic hydrogen column densities were derived over distances averaging 300 pc away from the sun. The OAO data were compared to synthetic ultraviolet spectra, originally derived from earlier higher resolution rocket observations, which were computer processed to simulate the effects of absorption by different amounts of hydrogen followed by the instrumental blending.

  15. Characteristics of advanced hydrogen maser frequency standards

    NASA Technical Reports Server (NTRS)

    Peters, H. E.

    1973-01-01

    In house research and development at Goddard Space Flight Center to provide advanced frequency and time standards for the most demanding applications is concentrated primarily in field operable atomic hydrogen masers. Some of the most important goals for the new maser designs have been improved long and short term stability, elimination of the need for auto tuning, increased maser oscillation level, improved hydrogen economy, increased operational life, minimization of operator control or monitoring, improvement in magnetic isolation or sensitivity, and reduction in size and weight. New design concepts which have been incorporated in these masers to achieve these goals are described. The basic maser assemblies and control systems have recently been completed; the masers are oscillating; and operational testing has begun. Data illustrating the improvements in maser performance was available and presented.

  16. Theoretical study of optical absorption in hydrogenated amorphous silicon

    NASA Astrophysics Data System (ADS)

    Pickett, W. E.; Papaconstantopoulos, D. A.; Economou, E. N.

    1983-08-01

    We present the first application of the coherent-potential approximation in the evaluation of optical absorption α(E) of a-SiHx with the use of a realistic multiband model. The optical gap is larger than the calculated density-of-states gap and the theoretical α(E) agrees well with experimental data. These results suggest that α(E) is determined primarily by the local H-Si configuration and short-range order, but that it is insensitive to the particular long-range order, which is not included in our model.

  17. Ignition and flame characteristics of cryogenic hydrogen releases

    DOE PAGES

    Panda, Pratikash P.; Hecht, Ethan S.

    2017-01-01

    In this work, under-expanded cryogenic hydrogen jets were investigated experimentally for their ignition and flame characteristics. The test facility described herein, was designed and constructed to release hydrogen at a constant temperature and pressure, to study the dispersion and thermo-physical properties of cryogenic hydrogen releases and flames. In this study, a non-intrusive laser spark focused on the jet axis was used to measure the maximum ignition distance. The radiative power emitted by the corresponding jet flames was also measured for a range of release scenarios from 37 K to 295 K, 2–6 barabs through nozzles with diameters from 0.75 tomore » 1.25 mm. The maximum ignition distance scales linearly with the effective jet diameter (which scales as the square root of the stagnant fluid density). A 1-dimensional (stream-wise) cryogenic hydrogen release model developed previously at Sandia National Laboratories (although this model is not yet validated for cryogenic hydrogen) was exercised to predict that the mean mole fraction at the maximum ignition distance is approximately 0.14, and is not dependent on the release conditions. The flame length and width were extracted from visible and infra-red flame images for several test cases. The flame length and width both scale as the square root of jet exit Reynolds number, as reported in the literature for flames from atmospheric temperature hydrogen. As shown in previous studies for ignited atmospheric temperature hydrogen, the radiative power from the jet flames of cold hydrogen scales as a logarithmic function of the global flame residence time. The radiative heat flux from jet flames of cold hydrogen is higher than the jet flames of atmospheric temperature hydrogen, for a given mass flow rate, due to the lower choked flow velocity of low-temperature hydrogen. Lastly, this study provides critical information with regard to the development of models to inform the safety codes and standards of hydrogen

  18. Ignition and flame characteristics of cryogenic hydrogen releases

    SciTech Connect

    Panda, Pratikash P.; Hecht, Ethan S.

    2017-01-01

    In this work, under-expanded cryogenic hydrogen jets were investigated experimentally for their ignition and flame characteristics. The test facility described herein, was designed and constructed to release hydrogen at a constant temperature and pressure, to study the dispersion and thermo-physical properties of cryogenic hydrogen releases and flames. In this study, a non-intrusive laser spark focused on the jet axis was used to measure the maximum ignition distance. The radiative power emitted by the corresponding jet flames was also measured for a range of release scenarios from 37 K to 295 K, 2–6 barabs through nozzles with diameters from 0.75 to 1.25 mm. The maximum ignition distance scales linearly with the effective jet diameter (which scales as the square root of the stagnant fluid density). A 1-dimensional (stream-wise) cryogenic hydrogen release model developed previously at Sandia National Laboratories (although this model is not yet validated for cryogenic hydrogen) was exercised to predict that the mean mole fraction at the maximum ignition distance is approximately 0.14, and is not dependent on the release conditions. The flame length and width were extracted from visible and infra-red flame images for several test cases. The flame length and width both scale as the square root of jet exit Reynolds number, as reported in the literature for flames from atmospheric temperature hydrogen. As shown in previous studies for ignited atmospheric temperature hydrogen, the radiative power from the jet flames of cold hydrogen scales as a logarithmic function of the global flame residence time. The radiative heat flux from jet flames of cold hydrogen is higher than the jet flames of atmospheric temperature hydrogen, for a given mass flow rate, due to the lower choked flow velocity of low-temperature hydrogen. Lastly, this study provides critical information with regard to the development of models to inform the safety codes and standards of hydrogen

  19. Mechanical properties and energy absorption characteristics of a polyurethane foam

    SciTech Connect

    Goods, S.H.; Neuschwanger, C.L.; Henderson, C.; Skala, D.M.

    1997-03-01

    Tension, compression and impact properties of a polyurethane encapsulant foam have been measured as a function of foam density. Significant differences in the behavior of the foam were observed depending on the mode of testing. Over the range of densities examined, both the modulus and the elastic collapse stress of the foam exhibited power-law dependencies with respect to density. The power-law relationship for the modulus was the same for both tension and compression testing and is explained in terms of the elastic compliance of the cellular structure of the foam using a simple geometric model. Euler buckling is used to rationalize the density dependence of the collapse stress. Neither tension nor compression testing yielded realistic measurements of energy absorption (toughness). In the former case, the energy absorption characteristics of the foam were severely limited due to the inherent lack of tensile ductility. In the latter case, the absence of a failure mechanism led to arbitrary measures of energy absorption that were not indicative of true material properties. Only impact testing revealed an intrinsic limitation in the toughness characteristics of the material with respect to foam density. The results suggest that dynamic testing should be used when assessing the shock mitigating qualities of a foam.

  20. A novel procedure to assess the non-enzymatic hydrogen-peroxide antioxidant capacity of metabolites with high UV absorption.

    PubMed

    Csepregi, Kristóf; Hideg, Éva

    2016-12-01

    Assays assessing non-enzymatic hydrogen peroxide antioxidant capacities are often hampered by the high UV absorption of the sample itself. This is a typical problem in studies using plant extracts with high polyphenol content. Our assay is based on comparing the 405 nm absorption of the product of potassium iodine and hydrogen peroxide in the presence and absence of a putative hydrogen peroxide reactive antioxidant. This method is free of interference with either hydrogen peroxide or antioxidant self-absorption and it is also suitable for high-throughput plate reader applications.

  1. Complex surface analytical investigations on hydrogen absorption and desorption processes of a TiMn2-based alloy.

    PubMed

    Schülke, Mark; Kiss, Gábor; Paulus, Hubert; Lammers, Martin; Ramachandran, Vaidyanath; Sankaran, Kannan; Müller, Karl-Heinz

    2009-04-01

    Metal hydrides are one of the most promising technologies in the field of hydrogen storage due to their high volumetric storage density. Important reaction steps take place at the very surface of the solid during hydrogen absorption. Since these reaction steps are drastically influenced by the properties and potential contamination of the solid, it is very important to understand the characteristics of the surface, and a variety of analytical methods are required to achieve this. In this work, a TiMn(2)-type metal hydride alloy is investigated by means of high-pressure activation measurements, X-ray photoelectron spectroscopy (XPS), secondary neutral mass spectrometry (SNMS) and thermal desorption mass spectrometry (TDMS). In particular, TDMS is an analytical tool that, in contrast to SIMS or SNMS, allows the hydrogen content in a metal to be quantified. Furthermore, it allows the activation energy for desorption to be determined from TDMS profiles; the method used to achieve this is presented here in detail. In the results section, it is shown that the oxide layer formed during manufacture and long-term storage prevents any hydrogen from being absorbed, and so an activation process is required. XPS measurements show the oxide states of the main alloy elements, and a layer 18 nm thick is determined via SNMS. Furthermore, defined oxide layers are produced and characterized in UHV using XPS. The influence of these thin oxide layers on the hydrogen sorption process is examined using TDMS. Finally, the activation energy of desorption is determined for the investigated alloy using the method presented here, and values of 46 kJ/mol for hydrogen sorbed in UHV and 103 kJ/mol for hydrogen originating from the manufacturing process are obtained.

  2. Absorption Characteristics of Vertebrate Non-Visual Opsin, Opn3

    PubMed Central

    Sugihara, Tomohiro; Nagata, Takashi; Mason, Benjamin; Koyanagi, Mitsumasa; Terakita, Akihisa

    2016-01-01

    Most animals possess multiple opsins which sense light for visual and non-visual functions. Here, we show spectral characteristics of non-visual opsins, vertebrate Opn3s, which are widely distributed among vertebrates. We successfully expressed zebrafish Opn3 in mammalian cultured cells and measured its absorption spectrum spectroscopically. When incubated with 11-cis retinal, zebrafish Opn3 formed a blue-sensitive photopigment with an absorption maximum around 465 nm. The Opn3 converts to an all-trans retinal-bearing photoproduct with an absorption spectrum similar to the dark state following brief blue-light irradiation. The photoproduct experienced a remarkable blue-shift, with changes in position of the isosbestic point, during further irradiation. We then used a cAMP-dependent luciferase reporter assay to investigate light-dependent cAMP responses in cultured cells expressing zebrafish, pufferfish, anole and chicken Opn3. The wild type opsins did not produce responses, but cells expressing chimera mutants (WT Opn3s in which the third intracellular loops were replaced with the third intracellular loop of a Gs-coupled jellyfish opsin) displayed light-dependent changes in cAMP. The results suggest that Opn3 is capable of activating G protein(s) in a light-dependent manner. Finally, we used this assay to measure the relative wavelength-dependent response of cells expressing Opn3 chimeras to multiple quantally-matched stimuli. The inferred spectral sensitivity curve of zebrafish Opn3 accurately matched the measured absorption spectrum. We were unable to estimate the spectral sensitivity curve of mouse or anole Opn3, but, like zebrafish Opn3, the chicken and pufferfish Opn3-JiL3 chimeras also formed blue-sensitive pigments. These findings suggest that vertebrate Opn3s may form blue-sensitive G protein-coupled pigments. Further, we suggest that the method described here, combining a cAMP-dependent luciferase reporter assay with chimeric opsins possessing the third

  3. Absorption Characteristics of Vertebrate Non-Visual Opsin, Opn3.

    PubMed

    Sugihara, Tomohiro; Nagata, Takashi; Mason, Benjamin; Koyanagi, Mitsumasa; Terakita, Akihisa

    2016-01-01

    Most animals possess multiple opsins which sense light for visual and non-visual functions. Here, we show spectral characteristics of non-visual opsins, vertebrate Opn3s, which are widely distributed among vertebrates. We successfully expressed zebrafish Opn3 in mammalian cultured cells and measured its absorption spectrum spectroscopically. When incubated with 11-cis retinal, zebrafish Opn3 formed a blue-sensitive photopigment with an absorption maximum around 465 nm. The Opn3 converts to an all-trans retinal-bearing photoproduct with an absorption spectrum similar to the dark state following brief blue-light irradiation. The photoproduct experienced a remarkable blue-shift, with changes in position of the isosbestic point, during further irradiation. We then used a cAMP-dependent luciferase reporter assay to investigate light-dependent cAMP responses in cultured cells expressing zebrafish, pufferfish, anole and chicken Opn3. The wild type opsins did not produce responses, but cells expressing chimera mutants (WT Opn3s in which the third intracellular loops were replaced with the third intracellular loop of a Gs-coupled jellyfish opsin) displayed light-dependent changes in cAMP. The results suggest that Opn3 is capable of activating G protein(s) in a light-dependent manner. Finally, we used this assay to measure the relative wavelength-dependent response of cells expressing Opn3 chimeras to multiple quantally-matched stimuli. The inferred spectral sensitivity curve of zebrafish Opn3 accurately matched the measured absorption spectrum. We were unable to estimate the spectral sensitivity curve of mouse or anole Opn3, but, like zebrafish Opn3, the chicken and pufferfish Opn3-JiL3 chimeras also formed blue-sensitive pigments. These findings suggest that vertebrate Opn3s may form blue-sensitive G protein-coupled pigments. Further, we suggest that the method described here, combining a cAMP-dependent luciferase reporter assay with chimeric opsins possessing the third

  4. In situ characterization of hydrogen absorption in nanoporous palladium produced by dealloying

    PubMed Central

    Wiednig, Christopher; Enzinger, Norbert; Würschum, Roland

    2016-01-01

    Summary Palladium is a frequently used model system for hydrogen storage. During the past few decades, particular interest was placed on the superior H-absorption properties of nanostructured Pd systems. In the present study nanoporous palladium (np-Pd) is produced by electrochemical dealloying, an electrochemical etching process that removes the less noble component from a master alloy. The volume and electrical resistance of np-Pd are investigated in situ upon electrochemical hydrogen loading and unloading. These properties clearly vary upon hydrogen ad- and absorption. During cyclic voltammetry in the hydrogen regime the electrical resistance changes reversibly by almost 10% upon absorbing approximately 5% H/Pd (atomic ratio). By suitable loading procedures, hydrogen concentrations up to almost 60% H/Pd were obtained, along with a sample thickness increase of about 5%. The observed reversible actuation clearly exceeds the values found in the literature, which is most likely due to the unique structure of np-Pd with an extraordinarily high surface-to-volume ratio. PMID:27826493

  5. In situ atomic force microscopy observation of hydrogen absorption/desorption by Palladium thin film

    NASA Astrophysics Data System (ADS)

    Matsumoto, Itoko; Sakaki, Kouji; Nakamura, Yumiko; Akiba, Etsuo

    2011-12-01

    Grain structure changes in Pd thin film during hydrogen absorption and desorption were observed by in situ atomic force microscopy. The as-sputtered film had a smooth flat surface with 20-30 nm grains. Film that absorbed hydrogen showed buckling, caused by the compressive stress due to lattice expansion as Pd metal reacted with hydrogen to form the hydride. Grains on the buckles were agglomerated and deformed unlike those on flat areas beside the buckles. Film that absorbed and then desorbed hydrogen still showed some buckling; however, many buckles shrank and flattened when the compressive stress of lattice expansion was released during desorption. On both the remaining and the shrunken buckles, grain agglomeration was retained; whereas, the deformed grains reverted back to their original form. X-ray diffraction indicated compressive residual stress in the as-sputtered film and tensile residual stress in the film after hydrogen absorption/desorption. These results indicate that irreversible grain agglomeration is related to residual tensile stress in the film although agglomeration occurs only on the buckled areas.

  6. Measurement of Hydrogen Absorption in Ternary Alloys with Volumetric (Sieverts Loop) Techniques

    SciTech Connect

    Aceves, S.

    2015-10-26

    The Sieverts loop is an inexpensive, robust and reliable methodology for calculating hydrogen absorption in materials [1]. In this approach, we start by storing a sample of the material being tested in the volume Vcell (Figure 1) and initiate the process by producing a high vacuum in the system while the material sample is heated to eliminate (most of) the hydrogen and other impurities previously absorbed. The system typically operates isothermally, with the volume Vref at ambient temperature and the sample at a temperature of interest – high enough to liquefy the alloy for the current application to nuclear fusion.

  7. Effects of cerium on the hydrogen absorption-desorption properties of rare earth-Mg-Ni hydrogen-absorbing alloys

    NASA Astrophysics Data System (ADS)

    Yasuoka, Shigekazu; Ishida, Jun; Kishida, Kyosuke; Inui, Haruyuki

    2017-04-01

    The influence of Ce addition on the phase constitution, microstructure, hydrogen absorption/desorption properties and battery performances of newly developed rare earth (RE)-Mg-Ni hydrogen-absorbing superlattice alloys for negative electrode materials in Ni-metal hydride (MH) batteries were investigated. The partial substitution of RE (La and Nd) with Ce results in a higher discharge performance and a lower cycle life in the battery. The Ce addition greatly affects the phase constitution, which is mainly characterized by increased formation of the AB2 phase (A = RE or Mg and B = Ni or Al). The existence of the AB2 phase is found to accelerate alloy pulverization and oxidation when the alloys are used as negative electrode materials in Ni-MH model cells. The accelerated pulverization and oxidation are considered to be responsible for the observed higher discharge performance and lower cycle life in the batteries, respectively.

  8. Excitonic Effects and the Optical Absorption Spectrum of Hydrogenated Si Clusters

    SciTech Connect

    Rohlfing, M.; Louie, S.G. |

    1998-04-01

    We calculate the optical absorption spectrum of hydrogen-terminated silicon clusters by solving the Bethe-Salpeter equation for the two-particle Green{close_quote}s function using an {ital ab initio} approach. The one-particle Green{close_quote}s function and the electron-hole interaction kernel are calculated within the GW approximation for the electron self-energy operator. Very large exciton binding energies are observed. Our results for the one-particle properties and the optical absorption spectra of the clusters are in very good agreement with available experimental data. {copyright} {ital 1998} {ital The American Physical Society}

  9. Carrier transport characteristics of H-terminated diamond films prepared using molecular hydrogen and atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Liu, Jin-long; Chen, Liang-xian; Zheng, Yu-ting; Wang, Jing-jing; Feng, Zhi-hong; Li, Cheng-ming

    2017-07-01

    The H-terminated diamond films, which exhibit high surface conductivity, have been used in high-frequency and high-power electronic devices. In this paper, the surface conductive channel on specimens from the same diamond film was obtained by hydrogen plasma treatment and by heating under a hydrogen atmosphere, respectively, and the surface carrier transport characteristics of both samples were compared and evaluated. The results show that the carrier mobility and carrier density of the sample treated by hydrogen plasma are 15 cm2·V-1·s-1 and greater than 5 × 1012 cm-2, respectively, and that the carrier mobilities measured at five different areas are similar. Compared to the hydrogen-plasma-treated specimen, the thermally hydrogenated specimen exhibits a lower surface conductivity, a carrier density one order of magnitude lower, and a carrier mobility that varies from 2 to 33 cm2·V-1·s-1. The activated hydrogen atoms restructure the diamond surface, remove the scratches, and passivate the surface states via the etching effect during the hydrogen plasma treatment process, which maintains a higher carrier density and a more stable carrier mobility.

  10. X-ray absorption study of ceria nanorods promoting the disproportionation of hydrogen peroxide.

    PubMed

    Wu, Tai-Sing; Zhou, Yunyun; Sabirianov, Renat F; Mei, Wai-Ning; Soo, Yun-Liang; Cheung, Chin Li

    2016-04-11

    A quasi in situ X-ray absorption study demonstrated that the disproportionation of hydrogen peroxide (H2O2) promoted by ceria nanorods was associated with a reversible Ce(3+)/Ce(4+) reaction and structural transformations in ceria. The direction of this reversible reaction was postulated to depend on the H2O2 concentration and the fraction of Ce(3+) species in ceria nanorods.

  11. Synthesis and enhanced microwave absorption properties: a strongly hydrogenated TiO2 nanomaterial

    NASA Astrophysics Data System (ADS)

    Xu, Jianle; Qi, Xiaosi; Luo, Chengzhi; Qiao, Jie; Xie, Ren; Sun, Yuan; Zhong, Wei; Fu, Qiang; Pan, Chunxu

    2017-10-01

    Due to its improved physical and chemical performances, a strongly hydrogenated TiO2 was designed and produced successfully by using a sealing-transfer reduction method at a relatively low temperature (425 °C). The microstructures, electromagnetic and microwave absorbing properties were investigated in detail. Experimental results revealed that: (1) the minimum reflection loss (RL) value of the hydrogenated TiO2 up to ‑53.8 dB (99.999 99% of EM wave attenuation) was reached at 11.2 GHz, and the RL values below ‑20 dB (99%) were obtained in a frequency range of 7.3–16.8 GHz. (2) Compared to pristine TiO2 and black TiO2 in other reports, the present hydrogenated TiO2 exhibited greatly improved microwave absorption performance. Moreover, the mechanism was also discussed. It was demonstrated that the excellent microwave absorption performance of the black TiO2 arose from the strong dielectric loss, excellent impedance matching and attention loss due to associated relaxation and interfacial polarization. It is expected that the hydrogenated TiO2 exhibits great potential applications in the area of high performance microwave absorbing materials. In addition, it is believed that the black TiO2 @ magnetic metals composites will display an excellent microwave absorbing property.

  12. Measurement of Gas Temperature in Negative Hydrogen Ion Source by Wavelength-Modulated Laser Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nishiyama, S.; Sasaki, K.; Nakano, H.; Goto, M.; Kisaki, M.; Tsumori, K.; NIFS-NBI Team

    2014-10-01

    Measurement of the energy distribution of hydrogen atom is important and essential to understand the production mechanism of its negative ion (H-) in cesium-seeded negative ion sources. In this work, we evaluated the temperature of atomic hydrogen in the large-scale arc-discharge negative hydrogen ion source in NIFS by wavelength-modulated laser absorption spectroscopy. The laser beam was passed through the adjacent region to the grid electrode for extracting negative ions. The frequency of the laser was scanned slowly over the whole range of the Doppler width (100 GHz in 1s). A sinusoidal frequency modulation at 600 Hz with a width of 30 GHz was superposed onto the slow modulation. The transmitted laser was detected using a photodiode, and its second harmonic component of the sinusoidal modulation was amplified using a lock-in amplifier. The obtained spectrum was in good agreement with an expected spectrum of the Doppler-broadened Balmer- α line. The estimated temperature of atomic hydrogen was approximately 3000 K. The absorption increased with the arc-discharge power, while the temperature was roughly independent of the power. This work is supported by the NIFS Collaboration Research Program NIFS13KLER021.

  13. Collision-Induced Infrared Absorption by Hydrogen-Helium gas mixtures at Thousands of Kelvin

    NASA Astrophysics Data System (ADS)

    Abel, Martin; Frommhold, Lothar; Li, Xiaoping; Hunt, Katharine L. C.

    2010-10-01

    The interaction-induced absorption by collisional pairs of H2 molecules is an important opacity source in the atmospheres of the outer planets and cool stars ^[1]. The emission spectra of cool white dwarf stars differ significantly in the infrared from the expected blackbody spectra of their cores, which is largely due to absorption by collisional H2--H2, H2--He, and H2--H complexes in the stellar atmospheres. Using quantum-chemical methods we compute the atmospheric absorption from hundreds to thousands of kelvin ^[2]. Laboratory measurements of interaction-induced absorption spectra by H2 pairs exist only at room temperature and below. We show that our results reproduce these measurements closely ^[2], so that our computational data permit reliable modeling of stellar atmosphere opacities even for the higher temperatures ^[2]. [1] L. Frommhold, Collision-Induced Absorption in Gases, Cambridge University Press, Cambridge, New York, 1993 and 2006 [2] Xiaoping Li, Katharine L. C. Hunt, Fei Wang, Martin Abel, and Lothar Frommhold, ``Collision-Induced Infrared Absorption by Molecular Hydrogen Pairs at Thousands of Kelvin'', International Journal of Spectroscopy, vol. 2010, Article ID 371201, 11 pages, 2010. doi: 10.1155/2010/371201

  14. Time-resolved Absorption Spectra of the Laser-dressed Hydrogen Atom

    NASA Astrophysics Data System (ADS)

    Murakami, Mitsuko; Chu, Shih-I.

    2013-05-01

    A theoretical study of the transient absorption spectra for the laser-dressed hydrogen atom based on the accurate numerical solution of the time-dependent Schrödinger equation is presented. The timing of absorption is controlled by the time delay between an isolated extreme ultraviolet (XUV) pulse and a dressing infrared (IR) field. We identify two different kinds of physical processes in the spectra. One is the formation of dressed states, signified by the appearance of sidebands between the XUV absorption lines separated by one IR-photon energy. We show that their population is maximized when the XUV pulse coincides with the zero-crossing of the IR field, and that their energy can be manipulated by using a chirped IR field. The other process is the dynamical AC Stark shift induced by the IR field and probed by the XUV pulse. Our calculations indicate that the accidental degeneracy of the hydrogen atom leads to the multiple splittings of each XUV absorption line whose separations change in response to a slowly-varying IR envelope. Furthermore, we observe the Autler-Townes doublets for the n=2 and 3 states using the 656 nm dressing field, but their separation does not agree with the prediction by the conventional 3-level model that neglects the dynamical AC Stark effects.

  15. Low-temperature hydrogen absorption in metallic nanocontacts studied by point-contact spectroscopy measurements

    NASA Astrophysics Data System (ADS)

    Takata, H.; Islam, M. S.; Ienaga, K.; Inagaki, Y.; Hashizume, K.; Kawae, T.

    2017-09-01

    We report on hydrogen (H) and deuterium (D) atoms absorption below T = 20 K in metallic palladium (Pd) via quantum tunnelling (QT). When a small bias voltage is applied between Pd nanocontacts that are immersed in liquid H2 (D2), the differential conductance spectra measured by point-contact spectroscopy change enormously. The results indicate H (D) absorption in Pd nanocontacts at the temperature where H (D) absorption due to thermal hopping process is not expected, and can be explained by QT. The QT occurs when the energy level of the potential well trapping the H (D) atom coincides with those not trapping the H (D) atom, and is assisted by phonons induced by ballistic electrons.

  16. Monte Carlo Simulation of the Optical Absorption of Hydrogenated Nanocrystalline Silicon Thin Films

    NASA Astrophysics Data System (ADS)

    Besahraoui, Fatiha; Sib, Jamal Dine; Bouizem, Yahia; Chahed, Larbi

    2008-05-01

    The optical absorption coefficient measured by Constant Photocurrent Method (CPM) for nanotextured silicon thin films is apparent affected by light scattering produced in these heterogeneous materials. A detailed Monte Carlo simulation of the absorption spectra and the random optical paths traveled by the scattered photons is presented for the case of nano-Si:H layers. The calculated values of apparent absorption coefficient and the mean optical path depend mainly on the variation of the included nanocrystallites fraction, which favors bulk light scattering phenomena. The particular structure of these materials is a key characteristic of efficient thin films solar cells.

  17. Metal hydrides reactors with improved dynamic characteristics for a fast cycling hydrogen compressor

    NASA Astrophysics Data System (ADS)

    Popeneciu, G.; Coldea, I.; Lupu, D.; Misan, I.; Ardelean, O.

    2009-08-01

    This paper presents an investigation of coupled heat and mass transfer process in metal hydrides hydrogen storage reactors. Hydrogen storage and compression performance of our designed and developed reactors are studied by varying the operating parameters and analyzing the effects of metal hydride bed parameters. The metal alloy selected to characterize the cycling behaviour of reactors is LaNi5, material synthesized and characterized by us in the range 20-80°C. Four types of metal hydride reactors were tested with the aim to provide a fast hydrogen absorption-desorption cycle, able to be thermally cycled at rapid rates. Some new technical solutions have been studied to make a step forward in reducing the duration of the reactors cycle, which combines the effective increase of the thermal conductivity and good permeability to hydrogen gas. Dynamic characteristic of developed fast metal hydride reactors is improved using our novel mixture metal hydride-CA conductive additive due to the increased effective thermal conductivity of the alloy bed. The advanced hydride bed design with high heat transfer capabilities can be thermally cycled at a rapid rate, under 120 seconds, in order to process high hydrogen flow rates.

  18. Absorption and desorption of hydrogen, deuterium, and tritium for Zr--V--Fe getter

    SciTech Connect

    Ichimura, K.; Inoue, N.; Watanabe, K.; Takeuchi, T.

    1984-07-01

    Nonevaporable getters have wide applicability for developing the tritium handling techniques for thermonuclear fusion devices. From this viewpoint, mechanisms of the absorption and desorption of hydrogen isotopes and the isotope effects were investigated for a Zr--V--Fe alloy (St-707) by means of the mass analyzed thermal desorption spectroscopy. It was observed that the absorption rate was proportional to the first power of the pressure, indicating that the rate limiting step is the dissociative adsorption of hydrogen isotopes on the surface. The activation energy was very small, in the order of magnitude of a few tens of calories per mole in a temperature range from -196 to 200 /sup 0/C. The desorption rate was proportional to the square of the amount of absorption, indicating that the rate limiting step is the associative desorption reaction of hydrogen atoms or ions diffused to the surface from the bulk. The rate constants for hydrogen and deuterium were determined as k/sub d/(H/sub 2/) = (5.3/sup +2.6//sub -1.7/)exp(-(28.0 +- 0.7) x 10/sup 3//RT) and k/sub d/(D/sub 2/) = (5.0/sup +2.7//sub -1.7/)exp(-(28.6 +- 0.8) x 10/sup 3//RT) in (1/Pa 1 s), respectively, where R is in (cal/mol deg). With regard to tritium, the rate constant was evaluated as k/sub d/(T/sub 2/) = (5.0/sup +20//sub -4.0/)exp(-(29.3 +- 3) x 10/sup 3//RT), however, the frequency factor will have to be corrected by knowing the relative sensitivity factor of the mass spectrometer for tritium (T/sub 2/).

  19. Absorption/desorption of hydrogen isotopes and isotopic waters by Zr-alloy getters

    SciTech Connect

    Ichimura, K.; Matsuyama, M.; Watanabe, K.; Takeuchi, T.

    1988-07-01

    Zr-alloy getters have been applied to tritium handling and vacuum conditioning for fusion devices. Some of their properties, however, should be improved to apply them in future devices. From this viewpoint, we have studied the effects of alloying on the getter properties of Zr alloys. We found that the activation energy of absorption and desorption of hydrogen varied considerably with alloying. The activation energy for hydrogen absorption was 0.74 for Zr/sub 61/Al/sub 39/, 0.01 for Zr/sub 57/V/sub 36/Fe/sub 7/, 0.63 for Zr/sub 67/Ni/sub 33/, and 2.8 kcal/mol for Zr/sub 85/Ni/sub 15/, whereas that for Zr was 2.6 kcal/mol. The heat of hydrogen absorption was 27.8 kcal/mol for Zr: it changed with alloying as 32.0--33.4 (Zr/sub 61/Al/sub 39/), 27.8--28.4 (Zr/sub 57/V/sub 36/Fe/sub 7/), 29.0 (Zr/sub 67/Ni/sub 33/), and 28.0 (Zr/sub 85/Ni/sub 15/). In addition, the ratio of the pumping speed of water vapor to that of hydrogen at room temperature varied with alloying element: for example, 1/40 for Zr/sub 57/V/sub 36/Fe/sub 7/ and 1/4 for Zr/sub 67/Ni/sub 33/. The alloying effects mentioned above are considered due to modification of the electronic and/or geometric structure of Zr with alloying.

  20. Concentration of atomic hydrogen in a dielectric barrier discharge measured by two-photon absorption fluorescence

    NASA Astrophysics Data System (ADS)

    Dvořák, P.; Talába, M.; Obrusník, A.; Kratzer, J.; Dědina, J.

    2017-08-01

    Two-photon absorption laser-induced fluorescence (TALIF) was utilized for measuring the concentration of atomic hydrogen in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar, H2 and O2 at atmospheric pressure. The method was calibrated by TALIF of krypton diluted in argon at atmospheric pressure, proving that three-body collisions had a negligible effect on quenching of excited krypton atoms. The diagnostic study was complemented with a 3D numerical model of the gas flow and a zero-dimensional model of the chemistry in order to better understand the reaction kinetics and identify the key pathways leading to the production and destruction of atomic hydrogen. It was determined that the density of atomic hydrogen in Ar-H2 mixtures was in the order of 1021 m-3 and decreased when oxygen was added into the gas mixture. Spatially resolved measurements and simulations revealed a sharply bordered region with low atomic hydrogen concentration when oxygen was added to the gas mixture. At substoichiometric oxygen/hydrogen ratios, this H-poor region is confined to an area close to the gas inlet and it is shown that the size of this region is not only influenced by the chemistry but also by the gas flow patterns. Experimentally, it was observed that a decrease in H2 concentration in the feeding Ar-H2 mixture led to an increase in H production in the DBD.

  1. Sound absorption characteristics of tree bark and forest floor

    Treesearch

    G. Reethof; O. H. McDaniel; G. M. Heisler

    1977-01-01

    Results of basic research on absorption of sound by tree bark and forest floors are presented. Amount of sound absorption by tree bark was determined by laboratory experiments with bark samples in a standing-wave tube. A modified portable standing-wave tube was used to measure absorption of sound by forest floors with different moisture contents, with and without leaf...

  2. Controllable nonlinear refraction characteristics in hydrogenated nanocrystalline silicon

    SciTech Connect

    Zheng, D. Q.; Ye, Q. H.; Shen, W. Z.; Su, W. A.

    2014-02-07

    Nonlinear refraction (NLR) of hydrogenated nanocrystalline silicon (nc-Si:H) has been investigated through the close aperture Z-scan method. We demonstrate a significant NLR and a unique feature of controllable NLR characteristics between saturable and Kerr NLR with the incident photon energy. We numerically evaluate the proportion of these two mechanisms in different wavelengths by a modified NLR equation. The band tail of nc-Si:H appears to play a crucial role in such NLR responses.

  3. Structural, morphological, magnetic and hydrogen absorption properties of LaNi5 alloy: A comprehensive study

    NASA Astrophysics Data System (ADS)

    Sarhaddi, Reza; Arabi, Hadi; Pourarian, Faiz

    2014-04-01

    A comprehensive study of structural, morphological, magnetic and hydrogen absorption properties of LaNi5-H system was investigated. The X-ray diffraction patterns show that as-synthesized LaNi5 alloy is single phase with CaCu5-type structure while some weak peaks of elemental nickel also appeared after several hydrogenation/dehydrogenation (H/D) cycling. The presence of pure Ni was also followed using the room temperature magnetic measurements. After H/D cycling, the particle size decreases and particle size distribution was found nearly uniform compared to noncycled alloy. The pressure-composition isotherms (PCIs) of the hydrogen absorption reaction were determined in the temperature range 20-80°C using a homemade Sievert's type experimental apparatus, and then the enthalpy and entropy of hydride formation were calculated. The hydriding kinetic mechanism of LaNi5 was evaluated using the different fitting models: Jander diffusion model (JDM), Johnson-Mehl-Avrami (JMA) and Chou models. All employed models confirm an increase in the hydriding reaction rate with temperature. However, the calculated results using JMA model show a better agreement with the experimental data and hence we believe that diffusion along with nucleation and growth is the rate-controlling step for the hydriding reaction. The values of activation energy for hydriding reaction were also obtained by JD and JMA models.

  4. Broadband Two-Photon Absorption Characteristics of Highly Photostable Fluorenyl-Dicyanoethylenylated [60] Fullerene Dyads (Postprint)

    DTIC Science & Technology

    2016-05-14

    AFRL-RX-WP-JA-2017-0138 BROADBAND TWO-PHOTON ABSORPTION CHARACTERISTICS OF HIGHLY PHOTOSTABLE FLUORENYL-DICYANOETHYLENYLATED [60] FULLERENE...ABSORPTION CHARACTERISTICS OF HIGHLY PHOTOSTABLE FLUORENYL-DICYANOETHYLENYLATED [60] FULLERENE DYADS (POSTPRINT) 5a. CONTRACT NUMBER FA8650-16-D...broadband characteristics of 1-Cn. We proposed that the observed broadband absorptions may be attributed by a partial -conjugation between the C60 > cage

  5. Hydrogen capacity and absorption rate of the SAES St707 non-evaporable getter at various temperatures.

    SciTech Connect

    Hsu, Irving; Mills, Bernice E.

    2010-08-01

    A prototype of a tritium thermoelectric generator (TTG) is currently being developed at Sandia. In the TTG, a vacuum jacket reduces the amount of heat lost from the high temperature source via convection. However, outgassing presents challenges to maintaining a vacuum for many years. Getters are chemically active substances that scavenge residual gases in a vacuum system. In order to maintain the vacuum jacket at approximately 1.0 x 10{sup -4} torr for decades, nonevaporable getters that can operate from -55 C to 60 C are going to be used. This paper focuses on the hydrogen capacity and absorption rate of the St707{trademark} non-evaporable getter by SAES. Using a getter testing manifold, we have carried out experiments to test these characteristics of the getter over the temperature range of -77 C to 60 C. The results from this study can be used to size the getter appropriately.

  6. THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES

    SciTech Connect

    Duley, W. W.; Hu, Anming E-mail: a2hu@uwaterloo.ca

    2012-12-20

    We report on the preparation of hydrogenated amorphous carbon nanoparticles whose spectral characteristics include an absorption band at 217.5 nm with the profile and characteristics of the interstellar 217.5 nm feature. Vibrational spectra of these particles also contain the features commonly observed in absorption and emission from dust in the diffuse interstellar medium. These materials are produced under ''slow'' deposition conditions by minimizing the flux of incident carbon atoms and by reducing surface mobility. The initial chemistry leads to the formation of carbon chains, together with a limited range of small aromatic ring molecules, and eventually results in carbon nanoparticles having an sp {sup 2}/sp {sup 3} ratio Almost-Equal-To 0.4. Spectroscopic analysis of particle composition indicates that naphthalene and naphthalene derivatives are important constituents of this material. We suggest that carbon nanoparticles with similar composition are responsible for the appearance of the interstellar 217.5 nm band and outline how these particles can form in situ under diffuse cloud conditions by deposition of carbon on the surface of silicate grains. Spectral data from carbon nanoparticles formed under these conditions accurately reproduce IR emission spectra from a number of Galactic sources. We provide the first detailed fits to observational spectra of Type A and B emission sources based entirely on measured spectra of a carbonaceous material that can be produced in the laboratory.

  7. EPR and optical absorption studies on Gd 3+ ions in ammonium hydrogen malonate single crystals

    NASA Astrophysics Data System (ADS)

    Kripal, Ram; Mishra, Indrajeet

    2010-01-01

    X-Band electron paramagnetic resonance (EPR) studies of Gd 3+ ions in ammonium hydrogen malonate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of four physically equivalent but magnetically inequivalent sites. The zero-field splitting parameters and g factor are determined. The Gd 3+ ion is in 8S state; its levels are split by the action of the crystalline electric field of monoclinic symmetry. The optical absorption spectra of Gd 3+ ions in single crystals of ammonium hydrogen malonate are also recorded at room temperature. The energy levels of the 4f 7 configuration are calculated and compared with those observed experimentally. The values of E1=5854±11, E2=31±0.36, E3=592±3.3 and ζ 4f=1595±25 cm -1 are found to give the best over-all agreement between experimentally observed and calculated levels.

  8. Microcalorimetric study of the absorption of hydrogen by palladium powders and carbon-supported palladium particles

    SciTech Connect

    Wunder, R.W.; Cobes, J.W.; Phillips, J.; Radovic, L.R. ); Lopez Peinado, A.J. ); Carrasco-Marin, F. )

    1993-04-01

    The adsorption and absorption of hydrogen on and in various forms of supported and unsupported palladium were studied using heat-flow calorimetry. The supports were found to have a tremendous effect on the nature of the hydrogen-palladium system. For palladium supported on silica or alumina, irreversible chemisorption was found to take place and be followed by bulk hydride formation. In contrast, it was found for carbon-supported particles that chemisorption does not take place and that the observed behavior could be explained by a model using only bulk hydride formation. It was further found that the heat of formation and equilibrium for [beta]-hydride formation are functions of particle size. It was not clear if surface adsorption takes place on unsupported palladium. 37 refs., 9 figs., 2 tabs.

  9. A high-efficiency power cycle in which hydrogen is compressed by absorption in metal hydrides.

    PubMed

    Powell, J R; Salzano, F J; Yu, W S; Milau, J S

    1976-07-23

    A high-efficiency power cycle is proposed in which molecular hydrogen gas is used as a working fluid in a regenerative closed Brayton cycle. The hydrogen gas is compressed by an absorption-desorption cycle on metal hydride (FeTiH(x)) beds. Low-temperature solar or geothermal heat (temperature about 100 degrees C) is used for the compression process, and high-temperature fossil fuel or nuclear heat (temperature about 700 degrees C) supplies the expansion work in the turbine. Typically, about 90 percent of the high-temperature heat input is converted to electricity, while about 3 kilowatts of low-temperature heat is required per kilowatt of electrical output.

  10. Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Lam, Royce K.; Smith, Jacob W.; Saykally, Richard J.

    2016-05-01

    While methanol and ethanol are macroscopically miscible with water, their mixtures exhibit negative excess entropies of mixing. Despite considerable effort in both experiment and theory, there remains significant disagreement regarding the origin of this effect. Different models for the liquid mixture structure have been proposed to address this behavior, including the enhancement of the water hydrogen bonding network around the alcohol hydrophobic groups and microscopic immiscibility or clustering. We have investigated mixtures of methanol, ethanol, and isopropanol with water by liquid microjet X-ray absorption spectroscopy on the oxygen K-edge, an atom-specific probe providing details of both inter- and intra-molecular structure. The measured spectra evidence a significant enhancement of hydrogen bonding originating from the methanol and ethanol hydroxyl groups upon the addition of water. These additional hydrogen bonding interactions would strengthen the liquid-liquid interactions, resulting in additional ordering in the liquid structures and leading to a reduction in entropy and a negative enthalpy of mixing, consistent with existing thermodynamic data. In contrast, the spectra of the isopropanol-water mixtures exhibit an increase in the number of broken alcohol hydrogen bonds for mixtures containing up to 0.5 water mole fraction, an observation consistent with existing enthalpy of mixing data, suggesting that the measured negative excess entropy is a result of clustering or micro-immiscibility.

  11. Simulations of collision-induced absorption of hydrogen on Ni(111)

    NASA Astrophysics Data System (ADS)

    Kindt, James T.; Tully, John C.

    1999-12-01

    Experiments by Ceyer and co-workers [Faraday Discuss. Chem. Soc. 91, 437 (1991)] have demonstrated that hydrogen atoms adsorbed on the Ni(111) surface can be driven below the surface under the impact of a hyperthermal (>2 eV) rare gas atom beam. We have modeled these experiments using classical molecular dynamics (MD) simulations, with the goal of elucidating the mechanism of this collision-induced absorption (CIA) process. The simulations favor a mechanism involving direct impact of the rare gas atom with an adsorbed hydrogen atom. The MD results are consistent with experiment in showing that the CIA efficiency increases with rare gas atomic mass for Ar, Kr, and Xe; interestingly, they predict a reversal of this trend when the rare gas is changed from Ne to He. These results are interpreted in terms of a crossover from a light collider regime of very efficient direct impulsive collisions to a massive collider regime of direct collisions strongly coupled to substrate dynamics and relaxation. The simulated CIA cross sections scaled approximately with normal incident collision energy, consistent with experiment. A hydrogen isotope effect, in which CIA was enhanced for deuterium with respect to hydrogen, was found in the simulations where none was observed experimentally. We show that this discrepancy may come from quantum effects, due to zero-point energies and to energy dissipation by electron-hole pair excitations, which tend to counteract and approximately cancel the isotopic difference observed in a purely classical simulation.

  12. Investigation of combustion characteristics of methane-hydrogen fuels

    NASA Astrophysics Data System (ADS)

    Vetkin, A. V.; Suris, A. L.; Litvinova, O. A.

    2015-01-01

    Numerical investigations of combustion characteristics of methane-hydrogen fuel used at present in tube furnaces of some petroleum refineries are carried out and possible problems related to change-over of existing furnaces from natural gas to methane-hydrogen fuel are analyzed. The effect of the composition of the blended fuel, associated temperature and emissivity of combustion products, temperature of combustion chamber walls, mean beam length, and heat release on variation in the radiation heat flux is investigated. The methane concentration varied from 0 to 100%. The investigations were carried out both at arbitrary given gas temperatures and at effective temperatures determined based on solving a set of equations at various heat-release rates of the combustion chamber and depended on the adiabatic combustion temperature and the temperature at the chamber output. The approximation dependence for estimation of the radiation heat exchange rate in the radiant chamber of the furnace at change-over to fuel with a greater hydrogen content is obtained. Hottel data were applied in the present work in connection with the impossibility to use approximated formulas recommended by the normative method for heat calculation of boilers to determine the gas emissivity, which are limited by the relationship of partial pressures of water steam and carbon dioxide in combustion products . The effect of the methane-hydrogen fuel on the equilibrium concentration of nitrogen oxides is also investigated.

  13. Cavity-enhanced measurements of hydrogen peroxide absorption cross sections from 353 to 410 nm.

    PubMed

    Kahan, Tara F; Washenfelder, Rebecca A; Vaida, Veronica; Brown, Steven S

    2012-06-21

    We report near-ultraviolet and visible absorption cross sections of hydrogen peroxide (H(2)O(2)) using incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS), a recently developed, high-sensitivity technique. The measurements reported here span the range of 353-410 nm and extend published electronic absorption cross sections by 60 nm to absorption cross sections below 1 × 10(-23) cm(2) molecule(-1). We have calculated photolysis rate constants for H(2)O(2) in the lower troposphere at a range of solar zenith angles by combining the new measurements with previously reported data at wavelengths shorter than 350 nm. We predict that photolysis at wavelengths longer than those included in the current JPL recommendation may account for up to 28% of the total hydroxyl radical (OH) production from H(2)O(2) photolysis under some conditions. Loss of H(2)O(2) via photolysis may be of the same order of magnitude as reaction with OH and dry deposition in the lower atmosphere; these processes have very different impacts on HO(x) loss and regeneration.

  14. Discovery of Variable Hydrogen Balmer Absorption Lines with Inverse Decrement in PG 1411+442

    NASA Astrophysics Data System (ADS)

    Shi, Xi-Heng; Pan, Xiang; Zhang, Shao-Hua; Sun, Lu-Ming; Wang, Jian-Guo; Ji, Tuo; Yang, Chen-Wei; Liu, Bo; Jiang, Ning; Zhou, Hong-Yan

    2017-07-01

    We present new optical spectra of the well-known broad absorption line (BAL) quasar PG 1411+442, using the DBSP spectrograph at the Palomar 200 inch telescope in 2014 and 2017 and the YFOSC spectrograph at the Lijiang 2.4 m telescope in 2015. A blueshifted narrow absorption line system is clearly revealed in 2014 and 2015 consisting of hydrogen Balmer series and metastable He i lines. The velocity of these lines is similar to the centroid velocity of the UV BALs, suggesting that both originate from the outflow. The Balmer lines vary significantly between the two observations and vanished in 2017. They were also absent in the archived spectra obtained before 2001. The variation is thought to be driven by photoionization change. Besides, the absorption lines show inversed Balmer decrement, i.e., the apparent optical depths of higher-order Balmer absorption lines are larger than those of lower-order lines, which is inconsistent with the oscillator strengths of the transitions. We suggest that such anomalous line ratios can be naturally explained by the thermal structure of a background accretion disk, which allows the obscured part of the disk to contribute differently to the continuum flux at different wavelengths. High-resolution spectroscopic and photometric monitoring would be very useful to probe the structure of the accretion disk as well as the geometry and physical conditions of the outflow.

  15. Size-dependent kinetic enhancement in hydrogen absorption and desorption of the Li-Mg-N-H system.

    PubMed

    Liu, Yongfeng; Zhong, Kai; Luo, Kun; Gao, Mingxia; Pan, Hongge; Wang, Qidong

    2009-02-11

    High operating temperature and slow kinetics retard the practical applications of the Li-Mg-N-H system for hydrogen storage. To alleviate these problems, a first attempt was carried out by synthesizing Li(2)MgN(2)H(2) through sintering a mixture of Mg(NH(2))(2)-2LiNH(2) and investigating its size-dependent hydrogen storage performance. A dramatically enhanced kinetics for hydrogen absorption/desorption was achieved with a reduction in the particle size. For the dehydrogenation reaction, a three-dimensional diffusion-controlled kinetic mechanism was identified for the first time by analyzing isothermal hydrogen desorption curves with a linear plot method. The experimental improvement and mechanistic understanding on the dehydrogenation kinetics of the Li-Mg-N-H system shed light on how to further decrease the operating temperature and enhance the hydrogen absorption/desorption rate of the amide/hydride combined materials.

  16. Zinc glycine chelate absorption characteristics in Sprague Dawley rat.

    PubMed

    Yue, M; Fang, S L; Zhuo, Z; Li, D D; Feng, J

    2015-06-01

    This study was conducted to investigate absorption characteristics of zinc glycine chelate (Zn-Gly) by evaluating tissues zinc status and the expression of zinc transporters in rats. A total of 24 male rats were randomly allocated to three treatments and administered either saline or 35 mg Zn/kg body weight from zinc sulphate (ZnSO4 ) or Zn-Gly by feeding tube separately. Four rats per group were slaughtered and tissues were collected at 2 and 6 h after gavage respectively. Our data showed that Zn-Gly did more effectively in increasing (p < 0.05) serum zinc levels, and the activities of serum and liver alkaline phosphatase (ALP) and liver Cu/Zn superoxide dismutase (Cu/Zn SOD) at 2 and 6 h. By 2 h after the zinc load, the mRNA and protein abundance of intestinal metallothionein1 (MT1) and zinc transporter SLC30A1 (ZnT1) were higher (p < 0.05), and zinc transporter SLC39A4 (Zip4) lower (p < 0.05) in ZnSO4 compared to other groups. Zinc transporter SLC39A5 (Zip5) mRNA expression was not zinc responsive, but Zip5 protein abundance was remarkably (p < 0.05) increased in ZnSO4 2 h later. Overall, our results indicated that in short-term periods, Zn-Gly was more effective in improving body zinc status than ZnSO4 , and ZnSO4 did more efficiently on the regulation of zinc transporters in small intestine. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

  17. Antioxidant content and ultraviolet absorption characteristics of human tears.

    PubMed

    Choy, Camus Kar Man; Cho, Pauline; Benzie, Iris F F

    2011-04-01

    Dry eye syndrome is a common age-related disorder, and decreased antioxidant/ultraviolet (UV) radiation protection in tears may be part of the cause. This study aimed to compare the tear antioxidant content and flow rate in young and older adults. The total antioxidant content and UV absorbing properties of various commercially available ophthalmic solutions used to alleviate dry eye symptoms were also examined. Minimally stimulated tears were collected from 120 healthy Chinese adults with no ocular pathology. Two age groups were studied: 19 to 29 years (n = 58) and 50 to 75 years (n = 62). Tear samples from each subject and 13 ophthalmic solutions were analyzed for total antioxidant content (as the Ferric Reducing/Antioxidant Power value). Tear flow rates were estimated from time taken to collect a fixed volume of tear fluid. UV absorbance spectra of pooled fresh reflex tear fluid and the ophthalmic solutions were determined. Results showed that the antioxidant content of minimally stimulated tears from older subjects (398 ± 160 μmol/l) was not significantly lower than that of younger subjects (348 ± 159 μmol/l; p = 0.0915). However, there was a significant difference in the tear flow rates between the two groups (p < 0.0001), with the younger group having three to four fold higher flow rate. None of the commercial preparations tested had detectable antioxidant content, and none showed the UV absorption characteristics of natural reflex tears. The effect of low flow rate on the dynamic antioxidant supply to the corneal surface indicates that older subjects have poorer overall defense against photooxidative and other oxidative processes. This could predispose older persons to corneal stress and development of dry eye syndrome. The commercially available artificial tears tested lack both the antioxidant content and UV absorbing characteristics of natural tears. Artificial tears formulations that help restore natural antioxidant and UV absorbing properties to the

  18. Optical hydrogen absorption consistent with a bow shock around the hot Jupiter HD 189733 b

    NASA Astrophysics Data System (ADS)

    Cauley, P. Wilson; Redfield, Seth; Jensen, Adam G.; Barman, Travis; Endl, Michael; Cochran, William D.

    Hot Jupiters, i.e., Jupiter-mass planets with orbital semi major axes of <10 stellar radii, can interact strongly with their host stars. If the planet is moving supersonically through the stellar wind, a bow shock will form ahead of the planet where the planetary magnetosphere slams into the the stellar wind or where the planetary outflow and stellar wind meet. Here we present high resolution spectra of the hydrogen Balmer lines for a single transit of the hot Jupiter HD 189733 b. Transmission spectra of the Balmer lines show strong absorption ~70 minutes before the predicted optical transit, implying a significant column density of excited hydrogen orbiting ahead of the planet. We show that a simple geometric bow shock model is able to reproduce the important features of the absorption time series while simultaneously matching the line profile morphology. Our model suggests a large planetary magnetic field strength of ~28 G. Follow-up observations are needed to confirm the pre-transit signal and investigate any variability in the measurement.

  19. Effect of biologically produced sulfur on gas absorption in a biotechnological hydrogen sulfide removal process.

    PubMed

    Kleinjan, Wilfred E; Lammers, Jos N J J; de Keizer, Arie; Janssen, Albert J H

    2006-07-05

    Absorption of hydrogen sulfide in aqueous suspensions of biologically produced sulfur particles was studied in a batch stirred cell reactor, and in a continuous set-up, consisting of a lab-scale gas absorber column and a bioreactor. Presence of biosulfur particles was found to enhance the absorption rate of H(2)S gas in the mildly alkaline liquid. The mechanism for this enhancement was however found to depend on the type of particles used. In the gently stirred cell reactor only small hydrophilic particles were present (d(p) < 3 microm) and the enhancement of the H(2)S absorption rate can be explained from the heterogeneous reaction between dissolved H(2)S and solid elemental sulfur to polysulfide ions, S(x) (2-). Conditions favoring enhanced H(2)S absorption for these hydrophilic particles are: low liquid side mass transfer (k(L)), high sulfur content, and presence of polysulfide ions. In the set-up of gas absorber column and bioreactor, both small hydrophilic particles and larger, more hydrophobic particles were continuously produced (d(p) up to 20 microm). Here, observed enhancement could not be explained by the heterogeneous reaction between sulfide and sulfur, due to the relatively low specific particle surface area, high k(L), and low [S(x) (2-)]. A more likely explanation for enhancement here is the more hydrophobic behavior of the larger particles. A local increase of the hydrophobic sulfur particle concentration near the gas/liquid interface and specific adsorption of H(2)S at the particle surface can result in an increase in the H(2)S absorption rate. (c) 2006 Wiley Periodicals, Inc.

  20. Hydrogen-assisted catalytic ignition characteristics of different fuels

    SciTech Connect

    Zhong, Bei-Jing; Yang, Fan; Yang, Qing-Tao

    2010-10-15

    Hydrogen-assisted catalytic ignition characteristics of methane (CH{sub 4}), n-butane (n-C{sub 4}H{sub 10}) and dimethyl ether (DME) were studied experimentally in a Pt-coated monolith catalytic reactor. It is concluded that DME has the lowest catalytic ignition temperature and the least required H{sub 2} flow, while CH{sub 4} has the highest catalytic ignition temperature and the highest required H{sub 2} flow among the three fuels. (author)

  1. Angle and Polarization Dependent Characteristics of Colloidal Quantum Dot Absorption in Fano Filters on Flexible Substrates

    DTIC Science & Technology

    2009-01-25

    infrared absorption characteristics for PbSe colloidal quantum dots ...TERMS colloidal quantum dots ,Fano resonances,Photonic crystals, Infrared photodetectors Li Chen, Hongjun Yang, Zexuan Qiang, Huiqing Pang, Zhenqiang...experimental investigations of infrared absorption characteristics for PbSe colloidal quantum dots in defect-free photonic crystal (PC) cavities, via

  2. Optimal Weld Parameters, Weld Microstructure, Mechanical Properties, and Hydrogen Absorption: An Effective Analysis

    NASA Astrophysics Data System (ADS)

    Bhattacharya, J.; Pal, T. K.

    2011-10-01

    Weld bead-in-grooves were deposited on low alloy, high strength steel plates (ASTM A 517 Grade "F") with a commercial flux-cored filler wire, Auto-MIG 420, at different welding conditions. Microstructure and mechanical properties of welds were characterized by means of optical microscopy, SEM, TEM, EPMA, microhardness measurements, tensile tests, and Charpy impact tests. Hydrogen content of weld metals in as-weld condition and after exposing in simulated service condition was measured by LECO Gas Analyzer. Microstructure of weld metals consisted primarily of lath martensite with small amount of M-A constituents (Martensite-Austenite alternating layers). For some particular welding conditions, such as higher heat input and lower preheat temperatures etc., acicular ferrite is observed with lath martensite. Welds consisting of acicular ferrite in the microstructure showed improved mechanical properties as well as lower hydrogen absorption. The study provides guidelines for selecting proper welding conditions, which results in lower propensity to absorb hydrogen during service, as well as better mechanical properties. Necessity of post-weld heat treatment processes, which is mainly performed to achieve toughness, may be reduced; consequently saving cost and time of the welding process.

  3. Absorption Reveals and Hydrogen Addition Explains New Interstellar Aldehydes: Propenal and Propanal

    NASA Technical Reports Server (NTRS)

    Hollis, J. M.; Jewell, P. R.; Lovas, F. J.; Remijan, A.; Mollendal, H.

    2004-01-01

    New interstellar molecules propenal (CH2CHCHO) and propanal (CH3CH2CHO) have been detected largely in absorption toward the star-forming region Sagittarius B2(N) by means of rotational transitions observed with the 100-m Green Bank Telescope (GBT) operating in the range of 18 GHz (lambda approximately 1.7 cm) to 26 GHz (lambda approximately 1.2 cm). The GBT was also used to observe the previously reported interstellar aldehyde propynal (HC2CHO) in Sagittarius B2(N) which is known for large molecules believed to form on interstellar grains. The presence of these three interstellar aldehydes toward Sagittarius B2(N) strongly suggests that simple hydrogen addition on interstellar grains accounts for successively larger molecular species: from propynal to propenal and from propenal to propanal. Energy sources within Sagittarius B2(N) likely permit the hydrogen addition reactions on grain surfaces to proceed. This work demonstrates that successive hydrogen addition is probably an important chemistry route in the formation of a number of complex interstellar molecules. We also searched for but did not detect the three-carbon sugar glyceraldehyde (CH2OHCHOHCHO).

  4. Characteristics of rapidly formed hydrogen-producing granules and biofilms.

    PubMed

    Zhang, Zhen-Peng; Adav, Sunil S; Show, Kuan-Yeow; Tay, Joo-Hwa; Liang, David Tee; Lee, Duu-Jong; Su, Ay

    2008-12-01

    The physicochemical and microbiological characteristics of rapidly formed hydrogen-producing granules and biofilms were evaluated in the present study. Microbial species composition was examined using the 16S rDNA-based separation and sequencing techniques, and spatial distribution and internal structure of microbial components were evaluated by examining the confocal laser scanning microscope (CLSM) images. Phylogenetic analysis indicated that a pure culture of Clostridium pasteurianum-like bacterium (98% similarity) was found in microbial community of granules and biofilms. It is postulated that containing such a species favored the rapid immobilization of hydrogen-producing culture. Manure granules and biofilms secreted 24-35 mg extracellulous proteins and 142-175 mg extracellulous polysaccharides in each gram of culture (in VSS). Such a high productivity of extracellulous polymers (ECP), a bio-glue to facilitate cell-to-cell and/or cell-to-substratum interaction, may work as the driving forces for the immobilization of C. pasteurianum. As abundant proteins were noted in the granule cores, it can be derived that rapid formation of the hydrogen-producing granules could be due to the establishment of precursor protein-rich microbial nuclei.

  5. Characteristic of Absorption Heat Transfer using LiBr+LiI Solution

    NASA Astrophysics Data System (ADS)

    Tsujimori, Atsushi; Ozaki, Eiichi; Nakao, Kazushige

    LiBr-H20 absorption chiller is widely used in Japan, and many research have been made for absorption characteristic in terms of enhancing heat transfer. Another study have been performed for widening working range with higher crystallization limits, and it was reported that adding LiI salt to LiBr-H20 working fluid provide about 5 [mass%] higher crystallization limit under the condition of absorption pressure range. It is necessary to reveal absorption heat transfer performance to utilize this working fluid pair for absorption chiller. In this study absorption heat transfer characteristic was investigated for horizontal and vertical tube. As a result, it was found that heat transfer coefficient increased as mass flow rate of solution increased and mass concentration of solution decrease and that these characteristic were almost the same as LiBr solution, though this solution gave slightly less heat transfer coefficient than LiBr solution.

  6. Evaluation of Hydrogen Storage System Characteristics for Light-Duty Vehicle Applications (Poster)

    SciTech Connect

    Thornton, M.; Day, K.; Brooker, A.

    2010-05-01

    This poster presentation demonstrates an approach to evaluate trade-offs among hydrogen storage system characteristic across several vehicle configurations and estimates the sensitivity of hydrogen storage system improvements on vehicle viability.

  7. Two Photon Absorption Laser Induced Fluorescence for Neutral Hydrogen Profile Measurements

    SciTech Connect

    Scime, Earl E.

    2016-09-23

    The magnitude and spatial dependence of neutral density in magnetic confinement fusion experiments is a key physical parameter, particularly in the plasma edge. Modeling codes require precise measurements of the neutral density to calculate charge-exchange power losses and drag forces on rotating plasmas. However, direct measurements of the neutral density are problematic. In this work, we proposed to construct a laser-based diagnostic capable of providing spatially resolved measurements of the neutral density in the edge of plasma in the DIII-D tokamak. The diagnostic concept is based on two-photon absorption laser induced fluorescence (TALIF). By injecting two beams of 205 nm light (co or counter propagating), ground state hydrogen (or deuterium or tritium) can be excited from the n = 1 level to the n = 3 level at the location where the two beams intersect. Individually, the beams experience no absorption, and therefore have no difficulty penetrating even dense plasmas. After excitation, a fraction of the hydrogen atoms decay from the n = 3 level to the n = 2 level and emit photons at 656 nm (the Hα line). Calculations based on the results of previous TALIF experiments in magnetic fusion devices indicated that a laser pulse energy of approximately 3 mJ delivered in 5 ns would provide sufficient signal-to-noise for detection of the fluorescence. In collaboration with the DIII-D engineering staff and experts in plasma edge diagnostics for DIII-D from Oak Ridge National Laboratory (ORNL), WVU researchers designed a TALIF system capable of providing spatially resolved measurements of neutral deuterium densities in the DIII-D edge plasma. The laser systems were specified, purchased, and assembled at WVU. The TALIF system was tested on a low-power hydrogen discharge at WVU and the plan was to move the instrument to DIII-D for installation in collaboration with ORNL researchers. After budget cuts at DIII-D, the DIII-D facility declined to support

  8. CHaracteristics of Two-Stage Absorption Heat Pump Cycler Driven by Waste Heat From Gas Engine

    NASA Astrophysics Data System (ADS)

    Kojima, Hiroshi; Akisawa, Atsushi; Kashiwagi, Takao

    Recently the energy conservation is expected from the global environment protection view point. In this study, a new concept of a compound gas cooling system using treated sewage water combining a gas engine heat pump and an absorption heat pump is proposed. In this system, the absorption heat pump is driven by the waste heat from the gas engine. In this paper, first, the best absorption cycle for this absorption heat pump is selected for the cooling and heating mode. And finally the simulation model of the two-stage absorption heat pumps for heating mode is demonstrated and the static characteristics are clarified.

  9. Absorption characteristics of elemental mercury in mercury chloride solutions.

    PubMed

    Ma, Yongpeng; Xu, Haomiao; Qu, Zan; Yan, Naiqiang; Wang, Wenhua

    2014-11-01

    Elemental mercury (Hg(0)) in flue gases can be efficiently captured by mercury chloride (HgCl2) solution. However, the absorption behaviors and the influencing effects are still poorly understood. The mechanism of Hg(0) absorption by HgCl2 and the factors that control the removal were studied in this paper. It was found that when the mole ratio of Cl(-) to HgCl2 is 10:1, the Hg(0) removal efficiency is the highest. Among the main mercury chloride species, HgCl3(-) is the most efficient ion for Hg(0) removal in the HgCl2 absorption system when moderate concentrations of chloride ions exist. The Hg(0) absorption reactions in the aqueous phase were investigated computationally using Moller-Plesset perturbation theory. The calculated Gibbs free energies and energy barriers are in excellent agreement with the results obtained from experiments. In the presence of SO3(2-) and SO2, Hg(2+) reduction occurred and Hg(0) removal efficiency decreased. The reduced Hg(0) removal can be controlled through increased chloride concentration to some degree. Low pH value in HgCl2 solution enhanced the Hg(0) removal efficiency, and the effect was more significant in dilute HgCl2 solutions. The presence of SO4(2-) and NO3(-) did not affect Hg(0) removal by HgCl2.

  10. Recent advances in SRS on hydrogen isotope separation using thermal cycling absorption process

    SciTech Connect

    Xiao, X.; Kit Heung, L.; Sessions, H.T.

    2015-03-15

    TCAP (Thermal Cycling Absorption Process) is a gas chromatograph in principle using palladium in the column packing, but it is unique in the fact that the carrier gas, hydrogen, is being isotopically separated and the system is operated in a semi-continuous manner. TCAP units are used to purify tritium. The recent TCAP advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10 of the current production system's footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects.

  11. Hydrogen absorption of titanium and nickel-titanium alloys during long-term immersion in neutral fluoride solution.

    PubMed

    Yokoyama, Ken'ichi; Ogawa, Toshio; Asaoka, Kenzo; Sakai, Jun'ichi

    2006-07-01

    Hydrogen absorption of biomedical titanium and Ni-Ti alloys in a neutral fluoride (2.0% NaF) solution for up to 10,000 h at 37 degrees C has been evaluated by means of hydrogen thermal desorption analysis. For alpha titanium (commercial pure titanium), the amount of absorbed hydrogen was, at most, 10-30 mass ppm, and the corrosion product and hydride formation were revealed on the surface of the specimen by X-ray diffraction analysis. Ni-Ti superelastic alloy absorbed approximately 150 mass ppm of hydrogen, which was probably sufficient to result in the pronounced degradation of the mechanical properties, although corrosion was hardly observed. In contrast, hydrogen absorption of alpha-beta titanium (Ti-6Al-4V) and beta titanium (Ti-11.3Mo-6.6Zr-4.3Sn) alloys was negligible, although general corrosion was observed. The results of the present study indicate that the susceptibility of titanium and Ni-Ti alloys to hydrogen absorption in the neutral fluoride solution is different from that in the acidic fluoride solution reported previously.

  12. Exospheric hydrogen density estimates from absorption dips in GOES solar irradiance measurements

    NASA Astrophysics Data System (ADS)

    Machol, J. L.; Loto'aniu, P. T. M.; Snow, M. A.; Viereck, R. A.; Woodraska, D.; Jones, A. R.; Bailey, J. J.; Gruntman, M.; Redmon, R. J.

    2015-12-01

    We use extreme ultraviolet (EUV) measurements of solar irradiance from GOES satellites to derive daily hydrogen (H) density distributions of the terrestrial upper atmosphere. GOES satellites are in geostationary orbit and measure solar irradiance in a wavelength band around the Lyman-alpha line. When the satellite is on the night-side of the Earth looking through the atmosphere at the Sun, the irradiance exhibits absorption/scattering loss. Using these daily dips in the measured irradiance, we can estimate a simple hydrogen density distribution for the exosphere based on the integrated scattering loss along the line of sight towards the Sun. We show preliminary results from this technique and compare the derived exospheric H density distributions with other data sets for different solar, geomagnetic and atmospheric conditions. The GOES observations will be available for many years into the future and so potentially can provide continuous monitoring of exospheric H density for use in full atmospheric models. These measurements may also provide a means to validate, calibrate and improve other exospheric models. Improved models will help with the understanding of the solar-upper atmospheric coupling and the decay of the ions in the magnetospheric ring current during geomagnetic storms. Long-term observations of trends can be used to monitor impacts of climate change and improved satellite drag models will help satellite operator adjust satellite orbits during geomagnetic storms. We discuss planned improvements to this technique.

  13. D Seuil D'absorption Optique des Multicouches Silicium Amorphe Hydrogene/nitrure de Silicium Amorphe Hydrogene

    NASA Astrophysics Data System (ADS)

    Beaudoin, Mario

    Hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon nitride (a-SiN_{ rm x}:H) multilayers (MC) are grown by the glow discharge method. The periodicity and interface abruptness of these structures are confirmed by X-ray reflection and X-ray photoelectron spectroscopy (XPS) studies. The multilayers' optical absorption edge is studied by transmission and reflection measurements as well as photothermal deflection spectroscopy (PDS) and Fourier transform photoacoustic spectroscopy (FTPAS). The electronic defect density is measured at 10^{16 } cm^{-3} for an a-Si:H sample and an interface defect density of about 10^{11} cm ^{-2} is measured for the MC. A structural disorder model links the generally observed increase of the Urbach tails with reduced well layer thickness to the interface disorder. An increase of the optical bandgap is generally reported in the literature when the well layer thickness is reduced below about 5nm. Even though the electron mean free path is about 1,0nm, and the k vector is no longer a good quantum number, this increase is usually attributed to the quantum confinement of carriers. However, Collins and Huang (Phys. Rev. B 34, 2910 (1986)) have suggested that it should be attributed to an artifact of the Tauc law used in determining the optical bandgap. In order to verify the Collins and Huang hypothesis, four series of samples were prepared. For two of these series, both the barrier thickness and the number of double-layers were kept constant while the well layer thickness was varied between 10nm and 1nm. These series are typical of those generally studied in the literature. A blue-shift of the Tauc bandgap is observed with a reduction of the well layer thickness, whereas the bandgap defined by the Cody law remains insensitive to it. For two other series, the composition and total sample thickness are kept constant in order to eliminate the possible artifact due to the Tauc law. For these series, both the Tauc and Cody

  14. Hydrogen sensing characteristics of Cu-PS-Si structures

    NASA Astrophysics Data System (ADS)

    Dzhafarov, T. D.; Omur, B. Can; Oruc, C.; Allahverdiev, Z. A.

    2002-12-01

    The effect of ambient humidity on the current-voltage characteristics of Cu-PS (porous silicon) structures was investigated. The humidity-voltaic effect, i.e. generation of humid voltage (Voc) in Cu-PS interface in humid atmosphere (up to 300 mV at 95% relative humidity) in dark and day-light illumination is discovered. Humidity-stimulated voltage generation is caused by the hydrogen component of water vapour of ambient. A possible mechanism of hydrogen-stimulated voltage generation in Cu-PS interface is suggested. Besides the effect of annealing in the range of 60-200°C in air on Voc of Cu-PS structures was studied and decrease of values of Voc depending on duration of annealing was discovered. These changes were attributed to diffusion of oxygen from air and oxidation of the copper film. (Voc-t) data were used for estimation of the diffusion coefficients of oxygen in the Cu film. The temperature dependence of the oxygen diffusion coefficient in Cu films is described by the relation D = 5.2×10-7exp(-0.44/kT).

  15. Characteristics of Single/Double-Effect Combination Absorption Refrigerator

    NASA Astrophysics Data System (ADS)

    Kimijima, Shinji; Waragai, Shisei; Uekusa, Tsuneo; Nakao, Masaki; Kawai, Sunao

    In recent years, co-generation system with fuel cell occupies the attention of the world from a standpoint of the environmental protection and the effective utilization of the energy. Since the waste heat of phosphoric acid fuel cell is recovered in two forms of steam (0.6 [MPa]) and hot water (65∼90 [°C]), this type of absorption refrigerator is driven by two heat sources. In this paper, we inquire the result of the experiment intented for this absorption refrigerator the standard cooling capacity of which is 35[kW]. It is recognized that there is a mutual intervention when the supply condition of steam pressure is changed. Also the effects of hot water temperature, cooling water temperature and chilled water temperature for the performance of this absorption refrigerator is clarified. As a result, the effectiveness of using steam and hot water simultaneously in year-round operation is shown. Furthermore, it is clarified that the utilization of the low boiling temperature medium as the heat transfer medium for air-conditioner is effective.

  16. Microwave Absorption Characteristics of Conventionally Heated Nonstoichiometric Ferrous Oxide

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Hwang, Jiann-Yang; Mouris, Joe; Hutcheon, Ron; Sun, Xiang

    2011-08-01

    The temperature dependence of the microwave absorption of conventionally heated nonstoichiometric ferrous oxide (Fe0.925O) was characterized via the cavity perturbation technique between 294 K and 1373 K (21 °C and 1100 °C). The complex relative permittivity and permeability of the heated Fe0.925O sample slightly change with temperature from 294 K to 473 K (21 °C to 200 °C). The dramatic variations of permittivity and permeability of the sample from 473 K to 823 K (200 °C to 550 °C) are partially attributed to the formation of magnetite (Fe3O4) and metal iron (Fe) from the thermal decomposition of Fe0.925O, as confirmed by the high-temperature X-ray diffraction (HT-XRD). At higher temperatures up to 1373 K (1100 °C), it is found that Fe0.925O regenerates and remains as a stable phase with high permittivity. Since the permittivity dominates the microwave absorption of Fe0.925O above 823 K (550 °C), resulting in shallow microwave penetration depth (~0.11 and ~0.015 m at 915 and 2450 MHz, respectively), the regenerated nonstoichiometric ferrous oxide exhibits useful microwave absorption capability in the temperature range of 823 K to1373 K (550 °C to 1100 °C).

  17. The effects of a static magnetic field on the microwave absorption of hydrogen plasma in carbon nanotubes: a numerical study

    NASA Astrophysics Data System (ADS)

    Peng, Zhi-Hua; Gong, Xue-Yu; Peng, Yan-Feng; Guo, Yan-Chun; Ning, Yan-Tao

    2012-07-01

    We theoretically investigate the microwave absorption properties of hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes under an external static magnetic field in the frequency range 0.3 GHz to 30 GHz, using the Maxwell equations in conjunction with a general expression for the effective complex permittivity of magnetized plasma known as the Appleton—Hartree formula. The effects of the external static magnetic field intensity and the incident microwave propagation direction on the microwave absorption of hydrogen plasma in CNTs are studied in detail. The numerical results indicate that the microwave absorption properties of hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes can be obviously improved when the external static magnetic field is applied to the material. It is found that the specified frequency microwave can be strongly absorbed by the hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes over a wide range of incidence angles by adjusting the external magnetic field intensity and the parameters of the hydrogen plasma.

  18. Relating water absorption features to soil moisture characteristics

    NASA Astrophysics Data System (ADS)

    Tian, Jia; Philpot, William D.

    2015-09-01

    The spectral reflectance of a sample of quartz sand was monitored as the sample progressed from air-dry to fully saturated, and then back to air-dry. Wetting was accomplished by spraying small amounts of water on the surface of the sample, and collecting spectra whenever change occurred. Drying was passive, driven by evaporation from the sand surface, with spectra collected every 5 minutes until the sample was air dry. Water content was determined by monitoring the weight of the sample through both wetting and drying. There was a pronounced difference in the pattern of change in reflectance during wetting and drying, with the differences being apparent both in spectral details (i.e., the depth of absorption bands) and in the magnitude of the reflectance for a particular water content. The differences are attributable to the disposition of water in the sample. During wetting, water initially occurred only on the surface, primarily as water adsorbed onto sand particles. With increased wetting the water infiltrated deeper into the sample, gradually covering all particles and filling the pore spaces. During drying, water and air were distributed throughout the sample for most of the drying period. The differences in water distribution are assumed to be the cause of the differences in reflectance and to the differences in the depths of four strong water absorption bands.

  19. Effects of lump characteristics on plutonium self absorption correction methods

    SciTech Connect

    Curtis, D. C.; Wormald, M. R.; Croft, S.

    2007-07-01

    An evaluation study has been undertaken to assess the robustness of several published Pu self-absorption correction methods against variation in size, shape, density etc. for use in the gamma assay of nuclear waste. The correction methods studied are a numerical plutonium self absorption correction (PuSAC) technique, the Fleissner 2-line, Fleissner 3-line and Infinite Energy Extrapolation methods with both linear and polynomial extrapolation to 1/E=0. The performance of these methods has been compared for a limited set of measured encapsulated PuO{sub 2} sources plus a range of modelled unencapsulated Pu lumps. An indication of the magnitude of the uncertainties of the numerical PuSAC method has been determined for cases of blind assays where the Pu material, shape and distribution are unknown with the aim of ultimately applying it to real waste. The importance of the range of Pu lumps used in the baseline modelled dataset has been examined. Data are presented to illustrate how the uncertainties in the method are affected by the shape, composition, density, number and mass distribution of Pu particles in a sample for a given modelled base dataset. (authors)

  20. Radio characteristics of Broad Absorption Lines (BAL) quasars

    NASA Astrophysics Data System (ADS)

    Ceglowski, Maciej

    2011-07-01

    Broad absorption lines (BALs), seen in a small fraction of both the radio-quiet and radio-loud quasar populations, are probably caused by the outflow of gas with high velocities and are part of the accretion process. The presence of BALs is the geometrical effect and/or it is connected with the quasar evolution. It has been believed that BALQSO occurs only among radio-quiet galaxies. However, in 2000 Becker et al. discovered the representative sample of radio-loud objects which exhibits broad absorption troughs. The radio morphologies of radio-loud BAL quasars provide important additional information about their orientation and the direction of the outflow. Using the final release of FIRST survey combined with a A Catalog of BAL QSOs (SDSS/DR3), we have constructed a new sample of compact radio-loud BAL QSOs, which makes the majority of radio-loud BAL QSOs. The main goal of this project is to study the origin of BALs by analysis the BAL QSOs radio morphology, their orientation and jets evolution, using EVN at 1.6 GHz and VLBA at 5 and 8.4 GHz.

  1. Energy absorption characteristics of lightweight structural member by stacking conditions

    NASA Astrophysics Data System (ADS)

    Choi, Juho; Yang, Yongjun; Hwang, Woochae; Pyeon, Seokbeom; Min, Hanki; Yeo, Ingoo; Yang, Inyoung

    2012-04-01

    The recent trend in vehicle design is aimed at improving crash safety and environmental-friendliness. To solve these issues, the needs for lighter vehicle to limit exhaust gas and improve fuel economy has been requested for environmental-friendliness. Automobile design should be made for reduced weight once the safety of vehicle is maintained. In this study, composite structural members were manufactured using carbon fiber reinforced plastic (CFRP) which are representative lightweight structural materials. Carbon fiber has been researched as alternative to metals for lightweight vehicle and better fuel economy. CFRP is an anisotropic material which is the most widely adapted lightweight structural member because of their inherent design flexibility and high specific strength and stiffness. Also, variation of CFRP interface number is important to increase the energy absorption capacity. In this study, one type of circular shaped composite tube was used, combined with reinforcing foam. The stacking condition was selected to investigate the effect of the fiber orientation angle and interface number. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed.

  2. Energy absorption characteristics of lightweight structural member by stacking conditions

    NASA Astrophysics Data System (ADS)

    Choi, Juho; Yang, Yongjun; Hwang, Woochae; Pyeon, Seokbeom; Min, Hanki; Yeo, Ingoo; Yang, Inyoung

    2011-11-01

    The recent trend in vehicle design is aimed at improving crash safety and environmental-friendliness. To solve these issues, the needs for lighter vehicle to limit exhaust gas and improve fuel economy has been requested for environmental-friendliness. Automobile design should be made for reduced weight once the safety of vehicle is maintained. In this study, composite structural members were manufactured using carbon fiber reinforced plastic (CFRP) which are representative lightweight structural materials. Carbon fiber has been researched as alternative to metals for lightweight vehicle and better fuel economy. CFRP is an anisotropic material which is the most widely adapted lightweight structural member because of their inherent design flexibility and high specific strength and stiffness. Also, variation of CFRP interface number is important to increase the energy absorption capacity. In this study, one type of circular shaped composite tube was used, combined with reinforcing foam. The stacking condition was selected to investigate the effect of the fiber orientation angle and interface number. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed.

  3. Performance characteristics of a medium power hydrogen arcjet

    NASA Astrophysics Data System (ADS)

    Glocker, B.; Auweter-Kurtz, M.

    1993-10-01

    Specific impulse levels and thrust efficiencies of an hydrogen arcjet are experimentally studied. Results show that with hydrogen as propellant, specific impulses of more than 1100 s with efficiencies of 35-40 percent can be achieved. Hydrogen arcjets are considered to be very attractive for orbit transfer applications of large satellites.

  4. Self-absorption characteristics of measured laser-induced plasma line shapes

    NASA Astrophysics Data System (ADS)

    Parigger, C. G.; Surmick, D. M.; Gautam, G.

    2017-02-01

    The determination of electron density and temperature is reported from line-of-sight measurements of laser-induced plasma. Experiments are conducted in standard ambient temperature and pressure air and in a cell containing ultra-high-pure hydrogen slightly above atmospheric pressure. Spectra of the hydrogen Balmer series lines can be measured in laboratory air due to residual moisture following optical breakdown generated with 13 to 14 nanosecond, pulsed Nd:YAG laser radiation. Comparisons with spectra obtained in hydrogen gas yields Abel-inverted line shape appearances that indicate occurrence of self-absorption. The electron density and temperature distributions along the line of sight show near-spherical rings, expanding at or near the speed of sound in the hydrogen gas experiments. The temperatures in the hydrogen studies are obtained using Balmer series alpha, beta, gamma profiles. Over and above the application of empirical formulae to derive the electron density from hydrogen alpha width and shift, and from hydrogen beta width and peak-separation, so-called escape factors and the use of a doubling mirror are discussed.

  5. Turbulent Flame Propagation Characteristics of High Hydrogen Content Fuels

    SciTech Connect

    Seitzman, Jerry; Lieuwen, Timothy

    2014-09-30

    This final report describes the results of an effort to better understand turbulent flame propagation, especially at conditions relevant to gas turbines employing fuels with syngas or hydrogen mixtures. Turbulent flame speeds were measured for a variety of hydrogen/carbon monoxide (H2/CO) and hydrogen/methane (H2/CH4) fuel mixtures with air as the oxidizer. The measurements include global consumption speeds (ST,GC) acquired in a turbulent jet flame at pressures of 1-10 atm and local displacement speeds (ST,LD) acquired in a low-swirl burner at atmospheric pressure. The results verify the importance of fuel composition in determining turbulent flame speeds. For example, different fuel-air mixtures having the same unstretched laminar flame speed (SL,0) but different fuel compositions resulted in significantly different ST,GC for the same turbulence levels (u'). This demonstrates the weakness of turbulent flame speed correlations based simply on u'/SL,0. The results were analyzed using a steady-steady leading points concept to explain the sensitivity of turbulent burning rates to fuel (and oxidizer) composition. Leading point theories suggest that the premixed turbulent flame speed is controlled by the flame front characteristics at the flame brush leading edge, or, in other words, by the flamelets that advance farthest into the unburned mixture (the so-called leading points). For negative Markstein length mixtures, this is assumed to be close to the maximum stretched laminar flame speed (SL,max) for the given fuel-oxidizer mixture. For the ST,GC measurements, the data at a given pressure were well-correlated with an SL,max scaling. However the variation with pressure was not captured, which may be due to non-quasi-steady effects that are not included in the current model. For the ST,LD data, the leading points model again faithfully captured the variation of turbulent flame speed over a wide range of fuel-compositions and turbulence intensities. These results provide

  6. Signatures of Hot Molecular Hydrogen Absorption from Protoplanetary Disks. I. Non-thermal Populations

    NASA Astrophysics Data System (ADS)

    Hoadley, Keri; France, Kevin; Arulanantham, Nicole; Parke Loyd, R. O.; Kruczek, Nicholas

    2017-09-01

    The environment around protoplanetary disks (PPDs) regulates processes that drive the chemical and structural evolution of circumstellar material. We perform a detailed empirical survey of warm molecular hydrogen (H2) absorption observed against H i-Lyα (Lyα: λ1215.67) emission profiles for 22 PPDs, using archival Hubble Space Telescope ultraviolet (UV) spectra to identify H2 absorption signatures and quantify the column densities of H2 ground states in each sightline. We compare thermal equilibrium models of H2 to the observed H2 rovibrational level distributions. We find that, for the majority of targets, there is a clear deviation in high-energy states (T exc ≳ 20,000 K) away from thermal equilibrium populations (T(H2) ≳ 3500 K). We create a metric to estimate the total column density of non-thermal H2 (N(H2)nLTE) and find that the total column densities of thermal (N(H2)) and N(H2)nLTE correlate for transition disks and targets with detectable C iv-pumped H2 fluorescence. We compare N(H2) and N(H2)nLTE to circumstellar observables and find that N(H2)nLTE correlates with X-ray and far-UV luminosities, but no correlations are observed with the luminosities of discrete emission features (e.g., Lyα, C iv). Additionally, N(H2) and N(H2)nLTE are too low to account for the H2 fluorescence observed in PPDs, so we speculate that this H2 may instead be associated with a diffuse, hot, atomic halo surrounding the planet-forming disk. We create a simple photon-pumping model for each target to test this hypothesis and find that Lyα efficiently pumps H2 levels with T exc ≥ 10,000 K out of thermal equilibrium.

  7. Quantum cascade laser-based multipass absorption system for hydrogen peroxide detection

    NASA Astrophysics Data System (ADS)

    Cao, Yingchun; Sanchez, Nancy P.; Jiang, Wenzhe; Ren, Wei; Lewicki, Rafal; Jiang, Dongfang; Griffin, Robert J.; Tittel, Frank K.

    2015-01-01

    Hydrogen peroxide (H2O2) is a relevant molecular trace gas species, that is related to the oxidative capacity of the atmosphere, the production of radical species such as OH, the generation of sulfate aerosol via oxidation of S(IV) to S(VI), and the formation of acid rain. The detection of atmospheric H2O2 involves specific challenges due to its high reactivity and low concentration (ppbv to sub-ppbv level). Traditional methods for measuring atmospheric H2O2 concentration are often based on wet-chemistry methods that require a transfer from the gas- to liquid-phase for a subsequent determination by techniques such as fluorescence spectroscopy, which can lead to problems such as sampling artifacts and interference by other atmospheric constituents. A quartz-enhanced photoacoustic spectroscopy-based system for the measurement of atmospheric H2O2 with a detection limit of 75 ppb for 1-s integration time was previously reported. In this paper, an updated H2O2 detection system based on long-optical-path-length absorption spectroscopy by using a distributed feedback quantum cascade laser (DFB-QCL) will be described. A 7.73-μm CW-DFB-QCL and a thermoelectrically cooled infrared detector, optimized for a wavelength of 8 μm, are employed for theH2O2 sensor system. A commercial astigmatic Herriott multi-pass cell with an effective optical path-length of 76 m is utilized for the reported QCL multipass absorption system. Wavelength modulation spectroscopy (WMS) with second harmonic detection is used for enhancing the signal-to-noise-ratio. A minimum detection limit of 13.4 ppb is achieved with a 2 s sampling time. Based on an Allan-Werle deviation analysis the minimum detection limit can be improved to 1.5 ppb when using an averaging time of 300 s.

  8. Real-time observation of hydrogen absorption by LaNi5 with quasi-dynamic neutron tomography

    NASA Astrophysics Data System (ADS)

    Wood, Bradley M.; Ham, Kyungmin; Hussey, Daniel S.; Jacobson, David L.; Faridani, Adel; Kaestner, Anders; Vajo, John J.; Liu, Ping; Dobbins, Tabbetha A.; Butler, Leslie G.

    2014-04-01

    The uptake of hydrogen by lanthanum pentanickel (LaNi5) to form lanthanum nickel hydride (LaNi5H6) is followed with three-dimensional imaging by neutron tomography. The hydrogen absorption process is slower than the time needed for acquiring a single radiograph, about 10 s, but fast relative to the time to acquire a fully-sampled tomographic data set, about 6000 s. A novel data acquisition scheme is used with angles based upon the Greek Golden ratio, a scheme which allows considerable flexibility in post-acquisition tomography reconstruction. Even with tomographic undersampling, the granular structure for the conversion of LaNi5 particles to LaNi5H6 particles is observed and visually tracked in 3D. Over the course of five sequential hydrogen uptake runs with various initial hydrogen pressures, some grains are repeatedly observed.

  9. Absorption and swelling characteristics of silver (I) antimicrobial wound dressings

    USDA-ARS?s Scientific Manuscript database

    An important characteristic of moist wound dressings is their ability to swell and absorb exudates from the wound, while maintaining a moist atmosphere at the wound site. At the Southern Regional Research Center (SRRC), we have previously developed antimicrobial silver-sodium-carboxymethylated (CM)-...

  10. Effect of TiO2 nanoparticles on the hydrogen sorption characteristics of magnesium hydride.

    PubMed

    Pandey, Sunita K; Bhatnagar, Ashish; Shahi, Rohit R; Hudson, M Sterlin Leo; Singh, Milind K; Srivastava, O N

    2013-08-01

    The present paper explores the enhancement in hydrogen sorption behavior of MgH2 with TiO2 nanoparticles. The catalytic effect of TiO2 nanoparticles with different sizes (7, 25, 50, 100 and 250 nm) were used for improving the sorption characteristics of MgH2. The MgH2 catalyzed with 50 nm of TiO2 exhibited the optimum catalytic effect for hydrogen sorption behavior. The desorption temperature of MgH2 catalyzed through 50 nm TiO2 was found to be 310 degrees C. This is 80 degrees C lower as compared to MgH2 having a desorption temperature of 390 degrees C. It was noticed that the dehydrogenated MgH2 catalyzed with 50 nm TiO2 reabsorbed 5.1 wt% of H2 within 6 minutes at temperature and pressure of 250 degrees C and 50 atm, respectively. The 50 nm TiO2 catalyst lowered the absorption activation energy of MgH2 from - 92 to - 52.7 kJ mol(-1).

  11. Infrared absorption and emission characteristics of interstellar PAHs

    NASA Technical Reports Server (NTRS)

    Barker, J. R.; Allamandola, Louis J.; Tielens, Alexander G. G. M.; Barker, J. R.; Barker, J. R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms are responsible for the emission.

  12. Hydrogen sensing characteristics from carbon nanotube field emissions

    NASA Astrophysics Data System (ADS)

    Dong, Changkun; Luo, Haijun; Cai, Jianqiu; Wang, Fuquan; Zhao, Yangyang; Li, Detian

    2016-03-01

    An innovative hydrogen sensing concept is demonstrated based on the field emission from multi-walled carbon nanotubes, where the low emission currents rise in proportion to hydrogen partial pressures above 10-9 Torr. Experimental and first principles studies reveal that the sensing mechanism is attributed to the effective work function reduction from dissociative hydrogen chemisorption. The embedded Ni catalyst would assist both the hydrogen dissociation and work function reduction. This technique is promising to build miniature low cost hydrogen sensors for multiple applications. This work is valuable for studies of nanocarbon-gas reaction mechanisms and the work function properties in adsorption related applications, including field emission, hydrogen storage, energy cells, and gas sensing.

  13. Quantification Of Cesium In Negative Hydrogen Ion Sources By Laser Absorption Spectroscopy

    SciTech Connect

    Fantz, U.; Wimmer, Ch.

    2011-09-26

    The use of cesium in negative hydrogen ion sources and the resulting cesium dynamics caused by the evaporation and redistribution in the vacuum and plasma phase makes a reliable and on-line monitoring of the cesium amount in the source highly desirable. For that purpose, a robust and compact laser absorption setup suitable for the ion source environment has been developed utilizing the Cs D{sub 2} resonance line at 852.1 nm. First measurements are taken in a small laboratory plasma chamber with cesium evaporation. A detection limit of {approx_equal}5x10{sup 13} m{sup -3} at a typical path length of 15 cm has been obtained with a dynamic range of more than three orders of magnitude, limited by line saturation at high densities. For on-line monitoring an automatic data analysis is established achieving a temporal resolution of 100 ms. The setup has then been applied to the ITER prototype ion sources developed at IPP. It is been shown that the method is well suited for routine measurements revealing a new insight into the cesium dynamics during source operation and cesium conditioning.

  14. CO2 Absorption Using Fluorine Functionalized Ionic Liquids: Interplay of Hydrogen and σ-Hole Interactions.

    PubMed

    Rao, Soniya S; Gejji, Shridhar P

    2016-03-03

    Use of ionic liquids (ILs) for CO2 capture offers certain advantages over currently used methodologies and is of growing interest. With this perspective, ILs composed of S-ethyl-N,N,N',N'-tetramethylthiouronium ([ETT]) and 1-hexyl-3-methylimidazolium ([Hmim]) cations and tris(pentafluoroethyl)trifluorophosphate ([FEP]) anion have been investigated. The present work unravels the noncovalent interactions accompanying CO2 capture by these ILs. Electronic structure of ion pairs and their CO2 absorbed [ETT][FEP]·n(CO2) and [Hmim][FEP]·n(CO2) (n up to 30) complexes are derived. The anisotropy in molecular electrostatic potential dictates the binding of CO2 through the interplay of (i) halogen bonding (O···F) between electron deficient σ-holes on fluorines, (ii) electrostatic C···F interactions between electron deficient carbons of CO2 and the electron-rich fluorine atoms, and the (iii) hydrogen bonding (O···H) interactions from the cation. The manifestations of these interactions on binding energies, polarizabilities, and vibrational spectra of CO2 absorbed complexes are presented. Consequent "frequency shift" accompanying hydrogen and halogen bonding exhibit complementary characteristics in the infrared spectra of CO2 absorbed complexes. Correlation of binding energies to absorbed CO2 molecules further demonstrate that [Hmim] based ILs are more efficient for CO2 capture applications.

  15. [Absorption Characteristics and Simulation of LLM-105 in the Terahertz Range].

    PubMed

    Meng, Zeng-rui; Shang, Li-ping; Du, Yu; Deng, Hu

    2015-07-01

    2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), a novel explosive with high energy and low sensibility. In order to study the molecular structure characteristics of the explosive, the absorption spectra of LLM-105 in the frequency range of 0.2-2.4 THz were detected by terahertz time-domain spectroscopy (THz-TDS). The results showed that a number of characteristic absorption peaks with different intensity located at 1.27, 1.59, 2.00, 2.08, 2.20, 2.29 THz. The article also simulated the absorption spectra of LLM-105 molecular crystal within 0.2-2.5 THz region by using Materials Studio 6.0 software based on density functional theory (DFT), and the simulated results agreed well with the experimental data except for the peak at 2.29 THz, which verified theoretically the accuracy of the experimental data. In addition, the vibrational modes of the characteristic peaks in the experimental absorption spectra were analyzed and identified, the results showed that the forming of the characteristic absorption peaks and the molecular vibration were closely related, which further provided important laboratory and technology support for the study of the transformation of molecule structure of LLM-105. There was no simulated frequency agreed with the experimental absorption peak at 2.29 THz, which may be caused by the vibration of the crystal lattice or other reasons.

  16. Hydrogen absorption in U3Si2 and its impact on electronic properties

    NASA Astrophysics Data System (ADS)

    Mašková, Silvie; Miliyanchuk, Khrystyna; Havela, Ladislav

    2017-04-01

    U3Si2 reversibly absorbs hydrogen at very low H2 pressures (kPa range), yielding U3Si2H1.8. One characteristic desorption temperature implies that there is only one type of H sites. U3Si2 is a weak Pauli paramagnet (χ < 2·10-8 m3/mol U) with the shortest inter-uranium distances between the U atoms in different sheets (dU-U = 332 pm). The volume-expanded (10%) hydride is a spin fluctuator with temperature dependent magnetic susceptibility and a weak ferromagnetic component gradually arising below T = 100 K. The location of U3Si2H1.8 at the verge of magnetic ordering is evidenced by the low temperature specific heat with an upturn in C/T and a dramatic enhancement of the Sommerfeld coefficient of electronic specific heat γ, which reaches 500 mJ/mol f.u. K2.

  17. Hydrogen Bonding Characteristics of Crystalline Water in Inorganic Crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Fangfang; Li, Keyan; Xue, Dongfeng

    From the chemical bond viewpoint, the microscopic characterstatics of hydrogen bonds in Mi—OH2⋯O (M is the metal cation coordinated to water molecule and i is the number of M) systems were comprehensively studied. It is shown that the original O—OH and H⋯O bond lengths of each hydrogen bonding system are evidently influenced by the crystalline environment and strongly dependent on the corresponding average bond lengths of each system, bar d{O - {H}} and bar d{H ... {O}}. Furthermore, the hydrogen bonding capability of water molecules coordinated to various metal cations was properly estimated and found to be related to the ionic electronegativities of these metal cations. The current work provides a useful route to calculating hydrogen bond valences within reasonable accuracy and sheds light on the rational utilization of hydrogen bonds in crystal design.

  18. Water absorption characteristics and structural properties of rice for sake brewing.

    PubMed

    Mizuma, Tomochika; Kiyokawa, Yoshifumi; Wakai, Yoshinori

    2008-09-01

    This study investigated the water absorption curve characteristics and structural properties of rice used for sake brewing. The parameter values in the water absorption rate equation were calculated using experimental data. Differences between sample parameters for rice used for sake brewing and typical rice were confirmed. The water absorption curve for rice suitable for sake brewing showed a quantitatively sharper turn in the S-shaped water absorption curve than that of typical rice. Structural characteristics, including specific volume, grain density, and powdered density of polished rice, were measured by a liquid substitution method using a Gay-Lussac pycnometer. In addition, we calculated internal porosity from whole grain and powdered grain densities. These results showed that a decrease in internal porosity resulted from invasion of water into the rice grain, and that a decrease in the grain density affected expansion during the water absorption process. A characteristic S-shape water absorption curve for rice suitable for sake brewing was related to the existence of an invisible Shinpaku-like structure.

  19. Absorption characteristics of lithium bromide (LiBr) solution constrained by superhydrophobic nanofibrous structures

    SciTech Connect

    Isfahani, RN; Moghaddam, S

    2013-08-01

    An experimental study on absorption characteristics of water vapor into a thin lithium bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure, cooling surface temperature, solution film thickness, and solution flow velocity on the absorption rate are studied. An absorption rate of approximately 0.006 kg/m(2) s was measured at a LiBr solution channel thickness and flow velocity of 100 mu m and 5 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the test conditions of this study. It was demonstrated that decreasing the solution film thickness and increasing the solution velocity enhance the absorption rate. The high absorption rate and the inherently compact form of the proposed,absorber facilitate development of compact small-scale waste heat or solar-thermal driven cooling systems. Published by Elsevier Ltd.

  20. A simplified model for the determination of current-voltage characteristics of a high pressure hydrogen plasma arc

    NASA Astrophysics Data System (ADS)

    Gueye, P.; Cressault, Y.; Rohani, V.; Fulcheri, L.

    2017-02-01

    This paper focuses on the modeling of a hydrogen arc column at very high pressure (20 bar). The problem is solved from Elenbaas-Heller equation where the radiation is carefully considered with the net emission coefficient. The absorption spectrum requires the integration of background continuum, molecular bands, and line spectra. This work directly aims to predict the electric current-voltage characteristics which is key for the design of new processes. We propose also a new analytic solution which generalizes the channel model of electric arc to the case when the volume radiation makes a significant contribution to the energy balance. The presented formalism allows a better determination of the plasma thickness parameter Rp for net emission coefficient method in cylindrical arcs and gives satisfactory results in comparison to earlier experimental works on high pressure hydrogen plasma.

  1. Simulation of hydrogen sulphide absorption in alkaline solution using a packed column.

    PubMed

    Azizi, Mohamed; Biard, Pierre-François; Couvert, Annabelle; Ben Amor, Mohamed

    2014-01-01

    In this work, a simulation tool was developed for hydrogen sulphide (H₂S) removal in an alkaline solution in packed columns working at countercurrent. Modelling takes into account the mass-transfer enhancement due to the reversible reactions between H₂S and the alkaline species (CO(²⁻)(3), HCO⁻(3), and HO⁻) in the liquid film. Many parameters can be controlled by the user such as the gas and liquid inlet H₂S concentrations, the gas and liquid flow rates, the scrubbing liquid pH, the desired H₂S removal efficiency, the temperature, the alkalinity, etc. Since the influence of the hydrodynamic and mass-transfer performances in a packed column is well known, the numerical resolutions performed were dedicated to the study of the influence of the chemical conditions (through the pH and the alkalinity), the temperature and the liquid-to-gas mass flow rate ratio (L/G). A packed column of 3 m equipped with a given random packing material working at countercurrent and steady state has been modelled. The results show that the H₂S removal efficiency increases with the L/G, the pH, the alkalinity and more surprisingly with the temperature. Alkalinity has a very significant effect on the removal efficiency through the mass-transfer enhancement and buffering effect, which limits pH decreasing due to H₂S absorption. This numerical resolution provides a tool for designers and researchers involved in H₂S treatment to understand deeper the process and optimize their processes.

  2. The visible light absorption property of Cu-doped hydrogen titanate nanotube thin films: An experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    An, Yongliang; Li, Zhonghua; Shen, Jun

    2013-11-01

    Hydrogen titanate nanotube thin films were synthesized by alkaline hydrothermal method using titanium plates as starting material and then doped with Cu through ion-exchange method. The experimental results show that Cu ions incorporate into the walls of nanotubes and exist as Cu2+. Cu doping leads to a red shift of the optical absorption edge from the ultraviolet region to the visible light region. First-principles calculation results reveal that Cu doping substantially reduces the band gap of hydrogen titanate nanotubes due to the presence of the impurity energy band of Cu 3d in intrinsic band gap. The valence and conduction band positions of Cu-doped hydrogen titanate nanotubes were determined by valence band spectra. The valence band is shifted to lower potential while the conduction band is shifted to higher potential after Cu doping, explaining the origin of the band gap narrowing and red shift.

  3. Integrated intensity of continuous absorption in infrared spectra of complexes with medium-strong and strong hydrogen bonds

    NASA Astrophysics Data System (ADS)

    Dega-Szafran, Zofia; Hrynio, Andrej; Szafran, Miroslaw

    A simple, nongraphical and reproducible method of separation of the complex absorption due to strong hydrogen bonds from that due to the skeleton is proposed. The method has been tested on 17 complexes of pyridine N-oxide, triphenylphosphine oxide and DMSO- d6 with dichloroacetic acid in dry dichloromethane and acetonitrile. The integrated intensity ( ACPA) and the centre of gravity (mathtype1) of complex absorption due to protonic vibration were measured and correlated with p Ka values of bases and chemical shifts of the hydrogen-bonded protons (δ), and discussed with respect to hydrogen bond strength variations. The ACPA values vary from 17.5 to 46 x 10 4 cm mmol -1 and were reproducible to within ± 1 x 10 4 cm mmol -1 (5-15 %). A nonlinear correlation between A CPA and (mathtype2) has been found in wide region of data; (mathtype3) varies from 500 to 2300 cm -1. A gradual proton transfer has been considered from the acid to pyridine N-oxides via strengthening intermolecular H-bonds, AH⋯ON, and further via weakening interionic H-bonds, A -⋯ HON +. The obtained correlations suggest that variations of hydrogen bond strength caused similar changes of A CPA and (mathtype4) both in molecular (A-H⋯B) and ionic (A -⋯H-B +) species.

  4. Gastrointestinal Inhibition of Sodium-Hydrogen Exchanger 3 Reduces Phosphorus Absorption and Protects against Vascular Calcification in CKD.

    PubMed

    Labonté, Eric D; Carreras, Christopher W; Leadbetter, Michael R; Kozuka, Kenji; Kohler, Jill; Koo-McCoy, Samantha; He, Limin; Dy, Edward; Black, Deborah; Zhong, Ziyang; Langsetmo, Ingrid; Spencer, Andrew G; Bell, Noah; Deshpande, Desiree; Navre, Marc; Lewis, Jason G; Jacobs, Jeffrey W; Charmot, Dominique

    2015-05-01

    In CKD, phosphate retention arising from diminished GFR is a key early step in a pathologic cascade leading to hyperthyroidism, metabolic bone disease, vascular calcification, and cardiovascular mortality. Tenapanor, a minimally systemically available inhibitor of the intestinal sodium-hydrogen exchanger 3, is being evaluated in clinical trials for its potential to (1) lower gastrointestinal sodium absorption, (2) improve fluid overload-related symptoms, such as hypertension and proteinuria, in patients with CKD, and (3) reduce interdialytic weight gain and intradialytic hypotension in ESRD. Here, we report the effects of tenapanor on dietary phosphorous absorption. Oral administration of tenapanor or other intestinal sodium-hydrogen exchanger 3 inhibitors increased fecal phosphorus, decreased urine phosphorus excretion, and reduced [(33)P]orthophosphate uptake in rats. In a rat model of CKD and vascular calcification, tenapanor reduced sodium and phosphorus absorption and significantly decreased ectopic calcification, serum creatinine and serum phosphorus levels, circulating phosphaturic hormone fibroblast growth factor-23 levels, and heart mass. These results indicate that tenapanor is an effective inhibitor of dietary phosphorus absorption and suggest a new approach to phosphate management in renal disease and associated mineral disorders. Copyright © 2015 by the American Society of Nephrology.

  5. Dynamic characteristics of the SMH actuator using hydrogen-absorbing alloys

    NASA Astrophysics Data System (ADS)

    Kim, Kyong; Pang, D. Y.; Choi, K. H.; Lee, S. C.; Kim, Y. Y.; Kwon, T. K.; Hong, C. U.; Kim, N. G.

    2005-12-01

    The dynamic characteristics of the special metal hydride(SMH) actuator using hydrogen absorbing alloys has been studied through the experiments on the characteristics of the temperature-pressure relation using a Peltier module. The SMH actuator uses the reversible reactions between thermal energy and mechanical energy inside hydrogen-absorbing alloys. It is well known that hydrogen-absorbing alloys can reversely absorb and desorb a large volume of hydrogen gas, more than about 1000 times of their own volume. By using Peltier element, we can actively control the energy conversion through hydrogen-absorbing alloys through hydriding and dehydriding reactions. Heating hydrogen-absorbing alloys using Peltier element will increase the equilibrium pressure of hydrogen gas resulting in the desorption of hydrogen gas by the alloys. Whereas, by cooling the alloys, the equilibrium pressure of hydrogen gas will decrease and hydrogen gas will be absorbed. In the present study, a simple special metal hydride (SMH) actuator, consisting of plated hydrogen-absorbing alloys as a power source, Peltier elements as a heat source, and a cylinder with metal bellows as a mechanical functioning part, has been developed. An electro-less copper plating has been used to improve the thermal conductivity of the hydrogen-absorbing alloys. To study the effects of the electro-less copper plating and the dynamic characteristics of the newly developed SMH actuator, a series of experiments has been performed and analyzed. The experiment demonstrated that the SMH actuator, which contains only 14.5 g of hydrogen-absorbing alloys, was able to easily lift 40 kg of weight with the displacement of 35 mm. The displacement of the cylinder was controlled in the periodic movement. The developed SMH actuator has merits in its small size, light weight, noiseless operation, and compliances similar to those of human bodies. Therefore, the SMH actuator is suitable for uses in medical and rehabilitation applications.

  6. Integral light-scattering and absorption characteristics of large, nonspherical particles

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander A.; Macke, Andreas

    1997-11-01

    We obtain and analyze simple analytical formulas for asymmetry parameters and absorption cross sections of large, nonspherical particles. The formulas are based on the asymptotic properties of these characteristics at strong and weak absorption of radiation inside particles. The absorption cross section depends on parameter , which determines the value of the light-absorption cross section for weakly absorbing particles. It is larger for nonspherical scatterers. The asymmetry parameter depends on two parameters. The first is the asymmetry parameter g0 of a nonspherical, transparent particle with the same shape as an absorbing one. The second parameter, , determines the strength of the influence of light absorption on the value of the asymmetry parameter. Parameter is larger for nonspherical particles. One can find these three parameters ( , g0 , and ) using a ray-tracing code (RTC) for nonabsorbing and weakly absorbing particles. The RTC can then be used to check the accuracy of the equations at any absorption for hexagonal cylinders and spheroids. It is found that the error of computing the absorption cross section and 1 -g (g is the asymmetry parameter) is less than 20% at the refractive index of particles n = 1.333. Values for asymmetry parameters of large, nonabsorbing, spheroidal particles with different aspect ratios are tabulated for the first time to our knowledge. They do not depend on the size of particles and can serve as an independent check of the accuracy of T-matrix codes for large parameters.

  7. Improvement of Electromagnetic Wave Absorption Ability by Reducing Impedance Oscillation Characteristics

    NASA Astrophysics Data System (ADS)

    Itoh, Masahiro; Terada, Masao; Sasada, Masaaki; Machida, Ken-ichi

    2012-01-01

    Improvement of the electromagnetic wave absorption ability was examined from the electromagnetic point of view. The oscillation behavior in relation to incident impedance derived from a hyperbolic tangent function can be reduced by increasing the imaginary part, i.e., loss value, of permeability and/or permittivity owing to its mathematical characteristics. It was demonstrated that the electromagnetic wave absorption ability was obviously enhanced by inserting the lossy magnetic layer between the electromagnetic wave absorber and a reflector. The absorption ability was improved further by pilling the polyurethane foam plate having lower permittivity to provide -9.6 dB (ca. 89% absorption) for the frequency range above 0.75 GHz with a total absorber thickness of 15.15 mm.

  8. Effect of the additional anode layers on the absorption enhancement characteristic of plasmonic organic solar cells

    NASA Astrophysics Data System (ADS)

    Yoo, Sanghyuk; Kim, Jungho

    2014-12-01

    We numerically investigate the effect of additional anode layers on the absorption enhancement characteristic of pyramidal-grating plasmonic organic solar cells (OSCs) using the finite element method. The behaviors of the plasmonic absorption enhancement are compared between a “simple” structure consisting of only the active and metal cathode layers and a “practical” structure with the additional anode layers. The plasmonic absorption enhancement is identified by comparing the polarization-dependent absorbance spectra between the planar and plasmonic OSCs. When the active-layer thickness is small, the plasmonic resonance condition changes owing to the addition of the anode layers. When the active-layer thickness is large, the plasmonic resonance condition and corresponding absorption behavior show a slight difference irrespective of the inclusion of the additional anode layers. Therefore, the additional anode layers should be included in the optical analysis and design of plasmonic OSCs when the active-layer thickness is small.

  9. Collision-Induced Infrared Absorption by Collisional Complexes in Dense Hydrogen-Helium Gas Mixtures at Thousands of Kelvin

    NASA Astrophysics Data System (ADS)

    Abel, Martin; Frommhold, Lothar; Li, Xiaoping; Hunt, Katharine L. C.

    2011-06-01

    The interaction-induced absorption by collisional pairs of H{_2} molecules is an important opacity source in the atmospheres of the outer planets and cool stars. The emission spectra of cool white dwarf stars differ significantly in the infrared from the expected blackbody spectra of their cores, which is largely due to absorption by collisional H{_2}-H{_2}, H{_2}-He, and H{_2}-H complexes in the stellar atmospheres. Using quantum-chemical methods we compute the atmospheric absorption from hundreds to thousands of kelvin. Laboratory measurements of interaction-induced absorption spectra by H{_2} pairs exist only at room temperature and below. We show that our results reproduce these measurements closely, so that our computational data permit reliable modeling of stellar atmosphere opacities even for the higher temperatures. L. Frommhold, Collision-Induced Absorption in Gases, Cambridge University Press, Cambridge, New York, 1993 and 2006 Xiaoping Li, Katharine L. C. Hunt, Fei Wang, Martin Abel, and Lothar Frommhold, "Collision-Induced Infrared Absorption by Molecular Hydrogen Pairs at Thousands of Kelvin", International Journal of Spectroscopy, vol. 2010, Article ID 371201, 11 pages, 2010. doi: 10.1155/2010/371201 M. Abel, L. Frommhold, X. Li, and K. L. C. Hunt, "Collision-induced absorption by H{_2} pairs: From hundreds to thousands of Kelvin," J. Phys. Chem. A, published online, DOI: 10.1021/jp109441f L. Frommhold, M. Abel, F. Wang, M. Gustafsson, X. Li, and K. L. C. Hunt, "Infrared atmospheric emission and absorption by simple molecular complexes, from first principles", Mol. Phys. 108, 2265, 2010

  10. Combustion characteristics of nanoaluminum, liquid water, and hydrogen peroxide mixtures

    SciTech Connect

    Sabourin, J.L.; Yetter, R.A.; Risha, G.A.; Son, S.F.; Tappan, B.C.

    2008-08-15

    An experimental investigation of the combustion characteristics of nanoaluminum (nAl), liquid water (H{sub 2}O{sub (l)}), and hydrogen peroxide (H{sub 2}O{sub 2}) mixtures has been conducted. Linear and mass-burning rates as functions of pressure, equivalence ratio ({phi}), and concentration of H{sub 2}O{sub 2} in H{sub 2}O{sub (l)} oxidizing solution are reported. Steady-state burning rates were obtained at room temperature using a windowed pressure vessel over an initial pressure range of 0.24 to 12.4 MPa in argon, using average nAl particle diameters of 38 nm, {phi} from 0.5 to 1.3, and H{sub 2}O{sub 2} concentrations between 0 and 32% by mass. At a nominal pressure of 3.65 MPa, under stoichiometric conditions, mass-burning rates per unit area ranged between 6.93 g/cm{sup 2} s (0% H{sub 2}O{sub 2}) and 37.04 g/cm{sup 2} s (32% H{sub 2}O{sub 2}), which corresponded to linear burning rates of 9.58 and 58.2 cm/s, respectively. Burning rate pressure exponents of 0.44 and 0.38 were found for stoichiometric mixtures at room temperature containing 10 and 25% H{sub 2}O{sub 2}, respectively, up to 5 MPa. Burning rates are reduced above {proportional_to}5 MPa due to the pressurization of interstitial spaces of the packed reactant mixture with argon gas, diluting the fuel and oxidizer mixture. Mass burning rates were not measured above {proportional_to}32% H{sub 2}O{sub 2} due to an anomalous burning phenomena, which caused overpressurization within the quartz sample holder, leading to tube rupture. High-speed imaging displayed fingering or jetting ahead of the normal flame front. Localized pressure measurements were taken along the sample length, determining that the combustion process proceeded as a normal deflagration prior to tube rupture, without significant pressure buildup within the tube. In addition to burning rates, chemical efficiencies of the combustion reaction were determined to be within approximately 10% of the theoretical maximum under all conditions

  11. Time-resolved X-Ray Absorption Spectroscopy of a Cobalt-Based Hydrogen Evolution System for Artificial Photosynthesis

    NASA Astrophysics Data System (ADS)

    Moonshiram, Dooshaye; Gimbert, Carolina; Lehmann, Carl; Southworth, Stephen; Llobet, Antoni; Argonne National Laboratory Team; Institut Català d'Investigació Química Collaboration

    2015-03-01

    Production of cost-effective hydrogen gas through solar power is an important challenge of the Department of Energy among other global industry initiatives. In natural photosynthesis, the oxygen evolving complex(OEC) can carry out four-electron water splitting to hydrogen with an efficiency of around 60%. Although, much progress has been carried out in determining mechanistic pathways of the OEC, biomimetic approaches have not duplicated Nature's efficiency in function. Over the past years, we have witnessed progress in developments of light harvesting modules, so called chromophore/catalytic assemblies. In spite of reportedly high catalytic activity of these systems, quantum yields of hydrogen production are below 40 % when using monochromatic light. Proper understanding of kinetics and bond making/breaking steps has to be achieved to improve efficiency of hydrogen evolution systems. This project shows the timing implementation of ultrafast X-ray absorption spectroscopy to visualize in ``real time'' the photo-induced kinetics accompanying a sequence of redox reactions in a cobalt-based molecular photocatalytic system. Formation of a Co(I) species followed by a Co(III) hydride species all the way towards hydrogen evolution is shown through time-resolved XANES.

  12. Non-noble metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution

    SciTech Connect

    Song, Jun-Ling; Zhang, Jian-Han; Mao, Jiang-Gao

    2016-05-15

    We reported the synthesis and crystal structures of alkali metal and alkali-earth metal phosphite, namely, CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} (1), and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} (2). Both compounds were prepared by hydrothermal reactions and feature unique new structures. They both exhibit 3D complicated frameworks based on VO{sub 6} octahedra which are connected by HPO{sub 3} tetrahedra via corner-sharing. Alkali or alkali earth metal cations are filled in the different channels of the frameworks. Topological analysis shows that the framework of CsV{sub 2}(H{sub 3}O) (HPO{sub 3}){sub 4} (1) is a new 3,3,3,4,5-connected network with the Schläfli symbol of {4.6"2}{sub 2}{4"2.6"6.8"2}{6"3}{6"5.8}. The investigations of X-ray photoelectron spectroscopy (XPS) and magnetic measurement on CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} suggest a +3 oxidation state of the vanadium ions in compound 1. Photocatalytic performance was evaluated by photocatalytic H{sub 2} evolution and degradation of methylene blue, which shows that both compounds exhibit activity under visible-light irradiation. IR spectrum, UV–vis-NIR spectrum and thermogravimetric analysis (TGA) of compounds were also investigated. - Graphical abstract: Metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution and the degradation of methylene blue aqueous solution. - Highlights: • Two new vanadium phosphites, CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6}, are reported. • CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} feature complicated 3D framework structures with different channels. • CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} exhibit strong and broad absorptions in the visible and Near IR region. • Photocatalytic properties of CsV{sub 2}(H{sub 3}O)(HPO{sub 3}){sub 4} and Ba{sub 3}V{sub 2}(HPO{sub 3}){sub 6} are investigated. • The magnetic

  13. Characteristics of Knock in Hydrogen-Oxygen-Argon SI Engine

    SciTech Connect

    Killingsworth, N; Rapp, V; Flowers, D; Aceves, S; Chen, J; Dibble, R

    2010-02-23

    A promising approach for improving the efficiency of internal combustion engines is to employ a working fluid with a high specific heat ratio such as the noble gas argon. Moreover, all harmful emissions are eliminated when the intake charge is composed of oxygen, nonreactive argon, and hydrogen fuel. Previous research demonstrated indicated thermal efficiencies greater than 45% at 5.5 compression ratio in engines operating with hydrogen, oxygen, and argon. However, knock limits spark advance and increasing the efficiency further. Conditions under which knock occurs in such engines differs from typical gasoline fueled engines. In-cylinder temperatures using hydrogen-oxygen-argon are higher due to the high specific heat ratio and pressures are lower because of the low compression ratio. Better understanding of knock under these conditions can lead to operating strategies that inhibit knock and allow operation closer to the knock limit. In this work we compare knock with a hydrogen, oxygen, and argon mixture to that of air-gasoline mixtures in a variable compression ratio cooperative fuels research (CFR) engine. The focus is on stability of knocking phenomena, as well as, amplitude and frequency of the resulting pressure waves.

  14. Detection of hydrogen peroxide based on long-path absorption spectroscopy using a CW EC-QCL

    NASA Astrophysics Data System (ADS)

    Sanchez, N. P.; Yu, Y.; Dong, L.; Griffin, R.; Tittel, F. K.

    2016-02-01

    A sensor system based on a CW EC-QCL (mode-hop-free range 1225-1285 cm-1) coupled with long-path absorption spectroscopy was developed for the monitoring of gas-phase hydrogen peroxide (H2O2) using an interference-free absorption line located at 1234.055 cm-1. Wavelength modulation spectroscopy (WMS) with second harmonic detection was implemented for data processing. Optimum levels of pressure and modulation amplitude of the sensor system led to a minimum detection limit (MDL) of 25 ppb using an integration time of 280 sec. The selected absorption line for H2O2, which exhibits no interference from H2O, makes this sensor system suitable for sensitive and selective monitoring of H2O2 levels in decontamination and sterilization processes based on Vapor Phase Hydrogen Peroxide (VPHP) units, in which a mixture of H2O and H2O2 is generated. Furthermore, continuous realtime monitoring of H2O2 concentrations in industrial facilities employing this species can be achieved with this sensing system in order to evaluate average permissible exposure levels (PELs) and potential exceedances of guidelines established by the US Occupational Safety and Health Administration for H2O2.

  15. Hydrogen absorption and structural analysis of TiZrNiV quasicrystals.

    PubMed

    Lee, Sang-Hwa; Jo, Youngsoo; Kim, Jaeyong

    2014-12-01

    Ti-based quasicrystals are known to store a high capacity of hydrogen exceeding the density of liquid hydrogen. Because TiZrNi quasicrystals contain a large number of tetrahedral sites formed with Ti and Zr atoms that are chemically favorable to hydrogen, these materials retain strong advantages for hydrogen storage applications in structurally and chemically. In fact, TiZrNi quasicrystals are known to absorb hydrogen maximum of the hydrogen to host metal ratio (H/M) value of near 2.0. The critical disadvantage, however, is that the equilibrium vapor pressure of hydrogen is very low (less than 1 Torr). To overcome this engineering drawback, we added a small amount of vanadium (V) in Ti(53-x)Zr27Ni20V(x), alloys (where x = 0 to 15) and rapidly quenched the molten ingots to form quasicrystals, and investigated the effects of V in terms of changes of structure, the H/M values, and an equilibrium vapor pressure of hydrogen. As the results, an equilibrium vapor pressure significantly increased from 0.84 to 2.16 Torr while the maximum H/M value decreased from 1.32 to 1.11 as increasing x = 0 to 8. After hydrogenation, the main peaks shifted evenly to the lower angle of 20 in X-ray diffraction patterns with uniform expansion of the quasilattice constants which demonstrates that hydrogen atoms homogeneously diffused into the samples. A Laves phase starts to form at x = 13 and the samples completely transformed to the phase at x = 15 suggesting the similarity between the quasicrystal and the Laves phase.

  16. Hydrogen venting characteristics of commercial carbon-composite filters and applications to TRU waste

    SciTech Connect

    Callis, E.L.; Marshall, R.S.; Cappis, J.H.

    1997-04-01

    The generation of hydrogen (by radiolysis) and of other potentially flammable gases in radioactive wastes which are in contact with hydrogenous materials is a source of concern, both from transportation and on-site storage considerations. Because very little experimental data on the generation and accumulation of hydrogen was available in actual waste materials, work was initiated to experimentally determine factors affecting the concentration of hydrogen in the waste containers, such as the hydrogen generation rate, (G-values) and the rate of loss of hydrogen through packaging and commercial filter-vents, including a new design suitable for plastic bags. This report deals only with the venting aspect of the problem. Hydrogen venting characteristics of two types of commercial carbon-composite filter-vents, and two types of PVC bag closures (heat-sealed and twist-and-tape) were measured. Techniques and equipment were developed to permit measurement of the hydrogen concentration in various layers of actual transuranic (TRU) waste packages, both with and without filter-vents. A test barrel was assembled containing known configuration and amounts of TRU wastes. Measurements of the hydrogen in the headspace verified a hydrogen release model developed by Benchmark Environmental Corporation. These data were used to calculate revised wattage Emits for TRU waste packages incorporating the new bag filter-vent.

  17. Load Absorption Force-Time Characteristics Following the Second Pull of Weightlifting Derivatives.

    PubMed

    Suchomel, Timothy J; Lake, Jason P; Comfort, Paul

    2017-06-01

    The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their 1-repetition maximum HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared with the HPC (p < 0.001; d = 3.77) and JS (p < 0.001; d = 5.48), whereas no difference existed between the HPC and JS (p = 0.573; d = 0.51). The JS produced significantly greater load absorption mean forces compared with the HPC (p < 0.001; d = 2.85) and HHP (p < 0.001; d = 3.75), whereas no difference existed between the HPC and HHP (p = 0.253; d = 0.37). Significantly more load absorption work was performed during the JS compared with the HPC (p < 0.001; d = 5.03) and HHP (p < 0.001; d = 1.69), whereas HHP load absorption work was also significantly greater compared with the HPC (p < 0.001; d = 4.81). The weightlifting pulling derivatives examined in the current study (JS and HHP) produced greater load absorption demands after the second pull compared with the weightlifting catching derivative (HPC). The JS and HHP may be used as effective training stimuli for load absorption during impact tasks such as jumping.

  18. Load absorption force-time characteristics following the second pull of weightlifting derivatives.

    PubMed

    Suchomel, Timothy J; Lake, Jason P; Comfort, Paul

    2016-09-21

    The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their one repetition maximum (1RM) HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared to the HPC (p < 0.001, d = 3.77) and JS (p < 0.001, d = 5.48), while no difference existed between the HPC and JS (p = 0.573, d = 0.51). The JS produced significantly greater load absorption mean forces compared to the HPC (p < 0.001, d = 2.85) and HHP (p < 0.001, d = 3.75), while no difference existed between the HPC and HHP (p = 0.253, d = 0.37). Significantly more load absorption work was performed during the JS compared to the HPC (p < 0.001, d = 5.03) and HHP (p < 0.001, d = 1.69), while HHP load absorption work was also significantly greater compared to the HPC (p < 0.001, d = 4.81). The weightlifting pulling derivatives examined in the current study (JS and HHP) produced greater load absorption demands following the second pull compared to the weightlifting catching derivative (HPC). The JS and HHP may be used as effective training stimuli for load absorption during impact tasks such as jumping.

  19. Improved absorption and in vivo kinetic characteristics of nanoemulsions containing evodiamine–phospholipid nanocomplex

    PubMed Central

    Hu, Jiangbo; Chen, Dilong; Jiang, Rong; Tan, Qunyou; Zhu, Biyue; Zhang, Jingqing

    2014-01-01

    Purpose The purpose of this study was to assess the improved absorption and in vivo kinetic characteristics of a novel water-in-oil nanoemulsion containing evodiamine–phospholipid nanocomplex (NEEPN) when administered orally. Methods NEEPN was fabricated by loading an evodiamine–phospholipid nanocomplex into a water-in-oil nanoemulsive system. The gastrointestinal absorption of NEEPN was investigated using an in situ perfusion method. The modified in vivo kinetic characteristics of evodiamine (EDA) in NEEPN were also evaluated. Results Compared with EDA or conventional nanoemulsions containing EDA instead of evodiamine–phospholipid complex, NEEPN with its favorable in vivo kinetic characteristics clearly enhanced the gastrointestinal absorption and oral bioavailability of EDA; for example, the relative bioavailability of NEEPN to free EDA was calculated to be 630.35%, and the effective permeability of NEEPN in the colon was 8.64-fold that of EDA. Conclusion NEEPN markedly improved the oral bioavailability of EDA, which was probably due to its increased gastrointestinal absorption. NEEPN also increased efficacy and reduced adverse effects for oral delivery of EDA. Such finding demonstrates great clinical significance as an ideal drug delivery system demands high efficacy and no adverse effects. PMID:25258531

  20. ABSORPTION OF NUTRIENTS AND PLANT GROWTH IN RELATION TO HYDROGEN ION CONCENTRATION

    PubMed Central

    Arrhenius, Olof

    1922-01-01

    The absorption of nutrients depends to a large extent on the reaction of the substrate. At maximal growth the intake of salt is at minimum. Different ions are very differently affected. The intake of water is independent of the absorption of salts. PMID:19871980

  1. Absorption characteristics of glass fiber materials at normal and oblique incidence. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Wyerman, B. R.

    1974-01-01

    The absorption characteristics of several fibrous materials of the Owens Corning 700 Fiberglas Series were measured to determine the variation in impedance as a function of incident angle of the sound wave. The results, indicate that the fibrous absorbents behave as extended reacting materials. The poor agreement between measurement and theory for sound absorption based on the parameters of flow resistance and porosity indicates that this theory does not adequately predict the acoustic behavior of fibrous materials. A much better agreement with measured results is obtained for values calculated from the bulk acoustic parameters of the material.

  2. Test of spectral emission and absorption characteristics of active optical fibers by direct side pumping.

    PubMed

    Zhang, Jianzhong; Luo, Yanhua; Sathi, Zinat M; Azadpeyma, Nilram; Peng, Gang-Ding

    2012-08-27

    Emission and absorption are two main properties of active optical fibers that are important for fiber amplifiers and lasers. We propose a direct side pumping scheme for non-deconstructive evaluation of active optical fibers. This scheme enables a simple in situ test of both emission and absorption characteristics without cutting fiber and produces good accuracy with very low pumping background. A commercial Er-doped fiber and a home-made Bi/Er co-doped optical fiber have been tested to demonstrate that the scheme is a useful alternative technique for characterizing active optical fiber or waveguides.

  3. The Effect of Heat on Structural Characteristics and Water Absorption Behavior of Agave Fibers

    NASA Astrophysics Data System (ADS)

    Saikia, Dip

    2008-04-01

    The structural characteristics and water absorptions behavior agave fibers were investigated over a range of temperature by using XRD, IR, TG and gravimetric methods. Three distinct thermal processes were observed during heating the fiber in the temperature range 310-760 K in air, oxygen and nitrogen invariably. The cellulose structures of the fibers were unaffected on heating up to 450 K. The samples showed thermal decomposition processes beyond 500 K. Fibers displayed a two-stage diffusion behavior. The structural parameters and kinetic of water absorption of the fibers at specific temperatures were analyzed.

  4. Starch absorption by healthy man evaluated by lactulose hydrogen breath test.

    PubMed

    Flourié, B; Florent, C; Etanchaud, F; Evard, D; Franchisseur, C; Rambaud, J C

    1988-01-01

    The amounts of hydrogen produced from starch and lactulose were compared to assess the accuracy of the hydrogen breath test with lactulose as standard to quantify starch malabsorption. The mean amounts of hydrogen produced from starch and lactulose were not different in fecal homogenates and in breath excretion after carbohydrate infusions into the cecum. Known amounts of starch infused into the cecum of 18 subjects were compared with amounts calculated from the total excess excretion of hydrogen in breath computed in relation to hydrogen production after the ingestion of 10 g lactulose; calculated amounts were 3.6 +/- 1.0, 9.9 +/- 1.3, and 22.0 +/- 3.4 g for the infusion of 5, 10, and 25 g of starch, respectively. The lactulose hydrogen breath test based on total excess hydrogen volume provides a valid measurement of the mean amount of starch metabolized in the colon in a group of subjects. However, large individual variations preclude its use in a given subject.

  5. Site dependent hardening of the lanthanum metal lattice by hydrogen absorption

    NASA Astrophysics Data System (ADS)

    Machida, A.; Watanuki, T.; Ohmura, A.; Ikeda, T.; Aoki, K.; Nakano, S.; Takemura, K.

    2011-03-01

    The compressibility of lanthanum (La) metal and its hydrides were measured at room temperature by high pressure synchrotron X-ray diffraction. La metal pressurized in a hydrogen medium forms a hydride with an fcc metal lattice, which likely contains hydrogen at a concentration close to 3.0 and persists over the measured pressure span up to 21 GPa. Equations of state have been determined by helium compression experiments for LaH 2 with tetrahedral interstitial sites fully occupied with hydrogen atoms and for LaH 2.46 with octahedral interstitial sites partially occupied with hydrogen atoms and tetrahedral sites fully occupied. Both hydrides possess fcc metal lattices. The bulk modulus values B0 are 66.7 ± 1.2 GPa for LaH 2 and 68.4±1.0 GPa for LaH 2.46. These values are three times larger than that of La metal and are very close to each other despite the difference in hydrogen occupation states. The hardening of the metal lattice by hydrogenation is attributed predominantly to hydrogen-metal interactions at the tetrahedral sites and is most pronounced for La, which has the largest ionic radius among rare-earth metals.

  6. Effects of hydrogen absorption in TbNiAl and UNiAl

    SciTech Connect

    Bordallo, H.N.; Nakotte, H.; Schultz, A.; Kolomiets, A.V.; Havela, L.; Andreev, A.V.

    1998-12-31

    Although hydrides of intermetallic compounds are used extensively as hydrogen-storage media, little is known about the exact nature of metal-hydrogen interactions. However, this knowledge is of essential importance for the understanding of thermodynamics and other properties. Hydrides (deuterides) of TbNiAl and UNiAl have been widely studied because of drastic increase of magnetic ordering temperature under hydrogenation. Here the authors report neutron-diffraction results of the three deuterides, TbNiAlD{sub 1.28}, TbNiAlD{sub 0.8}a nd UNiAlD{sub 2.23}.

  7. Calculation of near-edge x-ray-absorption fine structure at finite temperatures: spectral signatures of hydrogen bond breaking in liquid water.

    PubMed

    Hetényi, Balázs; De Angelis, Filippo; Giannozzi, Paolo; Car, Roberto

    2004-05-08

    We calculate the near-edge x-ray-absorption fine structure of H(2)O in the gas, hexagonal ice, and liquid phases using heuristic density-functional based methods. We present a detailed comparison of our results with experiment. The differences between the ice and water spectra can be rationalized in terms of the breaking of hydrogen bonds around the absorbing molecule. In particular the increase in the pre-edge absorption feature from ice to water is shown to be due to the breaking of a donor hydrogen bond. We also find that in water approximately 19% of hydrogen bonds are broken. (c) 2004 American Institute of Physics.

  8. Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite

    NASA Astrophysics Data System (ADS)

    Meiksin, Avery; Bolton, James S.; Puchwein, Ewald

    2017-06-01

    Modern theories of galaxy formation predict that galaxies impact on their gaseous surroundings, playing the fundamental role of regulating the amount of gas converted into stars. While star-forming galaxies are believed to provide feedback through galactic winds, quasi-stellar objects (QSOs) are believed instead to provide feedback through the heat generated by accretion on to a central supermassive black hole. A quantitative difference in the impact of feedback on the gaseous environments of star-forming galaxies and QSOs has not been established through direct observations. Using the Sherwood cosmological simulations, we demonstrate that measurements of neutral hydrogen in the vicinity of star-forming galaxies and QSOs during the era of peak galaxy formation show excess Ly α absorption extending up to comoving radii of ˜150 kpc for star-forming galaxies and 300-700 kpc for QSOs. Simulations including supernovae-driven winds account for the absorption around star-forming galaxies but not QSOs.

  9. Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite

    NASA Astrophysics Data System (ADS)

    Meiksin, Avery; Bolton, James S.; Puchwein, Ewald

    2017-01-01

    Modern theories of galaxy formation predict that galaxies impact on their gaseous surroundings, playing the fundamental role of regulating the amount of gas converted into stars. While star-forming galaxies are believed to provide feedback through galactic winds, Quasi-Stellar Objects (QSOs) are believed instead to provide feedback through the heat generated by accretion onto a central supermassive black hole. A quantitative difference in the impact of feedback on the gaseous environments of star-forming galaxies and QSOs has not been established through direct observations. Using the Sherwood cosmological simulations, we demonstrate that measurements of neutral hydrogen in the vicinity of star-forming galaxies and QSOs during the era of peak galaxy formation show excess Lyman-α absorption extending up to comoving radii of ˜150 kpc for star-forming galaxies and 300 - 700 kpc for QSOs. Simulations including supernovae-driven winds account for the absorption around star-forming galaxies but not QSOs.

  10. Spectral lineshapes of collision-induced absorption (CIA) using isotropic intermolecular potential for mixtures of molecular hydrogen with helium

    NASA Astrophysics Data System (ADS)

    El-Kader, M. S. A.; Maroulis, G.

    2017-09-01

    Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures for the collisional complex of a hydrogen molecule and a helium atom are computed using the numerical results of the induced dipole moment and isotropic intermolecular potential as input. Comparison with measured spectra and first three spectral moments shows good agreement over the rototranslational band in the far infrared. The quality of the present potentials have been checked by comparing between calculated and experimental thermo-physical and transport properties, which are found to be in good agreement.

  11. Modeling of pressure-induced far-infrared absorption spectra Molecular hydrogen pairs. [in outer planets atmospheres

    NASA Technical Reports Server (NTRS)

    Borysow, J.; Trafton, L.; Frommhold, L.; Birnbaum, G.

    1985-01-01

    Meyer et al. (1985) have calculated the accurate induced dipole moment function of H2-H2 from first principles, using highly correlated wave functions for the first time in such work. The present paper is concerned with the collision-induced translational-rotational absorption coefficient for molecular hydrogen pairs, taking into account computations on the basis of the fundamental theory considered by Meyer et al. Data have been obtained for temperatures in the range from 40 to 300 K. Criteria are developed for choosing among various model line shapes. It is found that certain models are capable of approximating the quantum profiles closely, with rms errors of only a few percent.

  12. Static Characteristics of Absorption Chiller-Heater Supplying Cold and Hot Water Simultaneously

    NASA Astrophysics Data System (ADS)

    Inoue, Naoyuki; Irie, Tomoyoshi

    Absorption chiller-heaters which can supply both chilled water and hot water at the same time, are used for cooling and heating air conditioning systems. In this paper, we classified absorption cold and hot water generating cycles and control methods, studied these absorption cycles by cycle simulation. In economizer cycle, condensed refrigerant which heats hot water is transported to cooling cycle and used effectively for cooling chilled water, Concerning with transported condensed refrigerant, there are two methods, all condensed refrigerant or required refrigerant for cooling are transported to cooling cycle, and required refrigerant method is better for energy saving. Adding improvement of solution control to this economizer cycle, simultaneous cold and hot water supplying chiller-heaters have good characteristics of energy saving in the all region.

  13. Femtosecond, two-photon-absorption, laser-induced-fluorescence (fs-TALIF) imaging of atomic hydrogen and oxygen in non-equilibrium plasmas

    NASA Astrophysics Data System (ADS)

    Schmidt, Jacob B.; Roy, Sukesh; Kulatilaka, Waruna D.; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.; Gord, James R.

    2017-01-01

    Femtosecond, two-photon-absorption laser-induced fluorescence (fs-TALIF) is employed to measure space- and time-resolved distributions of atomic hydrogen and oxygen in moderate-pressure, non-equilibrium, nanosecond-duration pulsed-discharge plasmas. Temporally and spatially resolved hydrogen and oxygen TALIF images are obtained over a range of low-temperature plasmas in mixtures of helium and argon at 100 Torr total pressure. The high-peak-intensity, low-average-energy fs pulses combined with the increased spectral bandwidth compared to traditional ns-duration laser pulses provide a large number of photon pairs that are responsible for the two-photon excitation, which results in an enhanced TALIF signal. Krypton and xenon TALIF are used for quantitative calibration of the hydrogen and oxygen concentrations, respectively, with similar excitation schemes being employed. This enables 2D collection of atomic-hydrogen and -oxygen TALIF signals with absolute number densities ranging from 2  ×  1012 cm-3 to 6  ×  1015 cm-3 and 1  ×  1013 cm-3 to 3  ×  1016 cm-3, respectively. These 2D images are the first application of TALIF imaging in moderate-pressure plasma discharges. 1D self-consistent modeling predictions show agreement with experimental results within the estimated experimental error of 25%. The present results can be used to further the development of higher fidelity kinetic models while quantifying plasma-source characteristics.

  14. Molar absorptivity and color characteristics of acylated and non-acylated pelargonidin-based anthocyanins.

    PubMed

    Giusti, M M; Rodríguez-Saona, L E; Wrolstad, R E

    1999-11-01

    The effects of glycosylation and acylation on the spectral characteristics, molar absorptivity, and color attributes of purified acylated and non-acylated pelargonidin derivatives were compared. Pigments were obtained from strawberries, radishes, red-fleshed potatoes, and partially hydrolyzed radish pigments. Individual pigments were isolated by using semipreparative HPLC. Spectral and color (CIELch) attributes of purified pigments were measured. Molar absorptivity ranged from 15 600 to 39 590 for pelargonidin-3-glucoside (pg-3-glu) and pg-3-rutinoside-5-glucoside acylated with p-coumaric acid, respectively. The presence of cinnamic acid acylation had a considerable impact on spectral and color characteristics, causing a bathochromic shift of lambda(max). Sugar substitution also played an important role, with a hypsochromic shift caused by the presence of glycosylation. Pg-3, 5-diglu and pg-3,5-triglu possessed a higher hue angle (>40 degrees ) than the other pg derivatives at pH 1.0, corresponding to the yellow-orange region of the color solid. Acylation with malonic acid did not affect lambda(max) and showed little effect on color characteristics. The solvent system had an effect not only on the molar absorptivity, but also on the visual color characteristic of the pigments.

  15. Characteristics of hydrogen bond revealed from water clusters

    NASA Astrophysics Data System (ADS)

    Song, Yan; Chen, Hongshan; Zhang, Cairong; Zhang, Yan; Yin, Yuehong

    2014-09-01

    The hydrogen bond network is responsible for the exceptional physical and chemical properties of water, however, the description of hydrogen bond remains a challenge for the studies of condensed water. The investigation of structural and binding properties of water clusters provides a key for understanding the H-bonds in bulk water. In this paper, a new set of geometric parameters are defined to describe the extent of the overlap between the bonding orbital of the donor OH and the nonbonding orbital of the lone-pair of the acceptor molecule. This orbital overlap plays a dominant role for the strength of H-bonds. The dependences of the binding energy of the water dimer on these parameters are studied. The results show that these parameters properly describe the H-bond strength. The ring, book, cage and prism isomers of water hexamer form 6, 7, 8 and 9 H-bonds, and the strength of the bonding in these isomers changes markedly. The internally-solvated and the all-surface structures of (H2O) n for n = 17, 19 and 21 are nearly isoenergetic. The internally-solvated isomers form fewer but stronger H-bonds. The hydrogen bonding in the above clusters are investigated in detail. The geometric parameters can well describe the characters of the H-bonds, and they correlate well with the H-bond strength. For the structures forming stronger H-bonds, the H-bond lengths are shorter, the angle parameters are closer to the optimum values, and their rms deviations are smaller. The H-bonds emanating from DDAA and DDA molecules as H-donor are relatively weak. The vibrational spectra of (H2O) n ( n = 17, 19 and 21) are studied as well. The stretching vibration of the intramolecular OH bond is sensitive to its bonding environment. The H-bond strength judged from the geometric parameters is in good agreement with the bonding strength judged from the stretching frequencies.

  16. Local structure and optical absorption characteristic investigation on Fe doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Tian-Xing; Feng, Ya-Juan; Huang, Jun-Heng; He, Jin-Fu; Liu, Qing-Hua; Pan, Zhi-Yun; Wu, Zi-Yu

    2015-02-01

    The local structures and optical absorption characteristics of Fe doped TiO2 nanoparticles synthesized by the sol-gel method were characterized by X-ray diffraction (XRD), X-ray absorption fine structure spectroscopy (XAFS) and ultraviolet-visible absorption spectroscopy (UV-Vis). XRD patterns show that all Fe-doped TiO2 samples have the characteristic anatase structure. Accurate Fe and Ti K-edge EXAFS analysis further reveal that all Fe atoms replace Ti atoms in the anatase lattice. The analysis of UV-Vis data shows a red shift to the visible range. According to the above results, we claim that substitutional Fe atoms lead to the formation of structural defects and new intermediate energy levels appear, narrowing the band gap and extending the optical absorption edge towards the visible region. Supported by National Basic Research Program of China (2012CB825801), Science Fund for Creative Research Groups of NSFC (11321503), National Natural Science Foundation of China (11321503, 11179004) and Guangdong Natural Science Foundation (S2011040003985)

  17. Absolute bioavailability and absorption characteristics of divalproex sodium extended-release tablets in healthy volunteers.

    PubMed

    Dutta, Sandeep; Reed, Ronald C; Cavanaugh, John H

    2004-07-01

    Conventional delayed-release, enteric-coated divalproex sodium tablet has an absolute bioavailability of approximately 100%. Divalproex sodium extended-release (ER) tablet is a novel formulation of valproic acid (VPA) designed to release the drug slowly at a constant zero-order rate. The purpose of this study was to evaluate the absolute bioavailability and absorption characteristics of divalproex ER. Healthy adult volunteers (n = 16) received divalproex ER and intravenous VPA in crossover fashion. Absolute bioavailability was calculated as the divalproex ER/intravenous VPA ratio of area under the curve extrapolated to infinity. The duration and rate of absorption of VPA from divalproex ER tablets were determined by deconvolution analysis. The geometric mean absolute bioavailability of divalproex ER was 0.896. The mean (coefficient of variation) duration of drug absorption from divalproex ER was 21.8 (17%) hours, and the zero-order absorption rate was 21.6 (24%) mg/h for a 500-mg tablet. Divalproex ER has a lower absolute bioavailability than conventional divalproex tablets but exhibits good extended-release characteristics without any dose dumping.

  18. Ignition and flame characteristics of [under-expanded] cryogenic hydrogen releases

    DOE PAGES

    Panda, Pratikash P.; Hecht, Ethan S.

    2016-09-04

    In this work, under-expanded cryogenic hydrogen jets were investigated experimentally for their ignition and flame characteristics. The test facility described herein, was designed and constructed to release hydrogen at a constant temperature and pressure, to study the dispersion and thermo-physical properties of cryogenic hydrogen releases and flames. In this study, a non-intrusive laser spark focused on the jet axis was used to measure the maximum ignition distance. The radiative power emitted by the corresponding jet flames was also measured for a range of release scenarios from 37 K to 295 K, 2–6 barabs through nozzles with diameters from 0.75 tomore » 1.25 mm. The maximum ignition distance scales linearly with the effective jet diameter (which scales as the square root of the stagnant fluid density). A 1-dimensional (stream-wise) cryogenic hydrogen release model developed previously at Sandia National Laboratories (although this model is not yet validated for cryogenic hydrogen) was exercised to predict that the mean mole fraction at the maximum ignition distance is approximately 0.14, and is not dependent on the release conditions. The flame length and width were extracted from visible and infra-red flame images for several test cases. The flame length and width both scale as the square root of jet exit Reynolds number, as reported in the literature for flames from atmospheric temperature hydrogen. As shown in previous studies for ignited atmospheric temperature hydrogen, the radiative power from the jet flames of cold hydrogen scales as a logarithmic function of the global flame residence time. The radiative heat flux from jet flames of cold hydrogen is higher than the jet flames of atmospheric temperature hydrogen, for a given mass flow rate, due to the lower choked flow velocity of low-temperature hydrogen. Lastly, this study provides critical information with regard to the development of models to inform the safety codes and standards of hydrogen

  19. Hydrogen absorption properties of amorphous (Ni0.6Nb0.4-yTay ) 100-x Zr x membranes

    DOE PAGES

    Palumbo, O.; Trequattrini, F.; Pal, N.; ...

    2017-02-01

    Ni based amorphous materials have great potential as hydrogen purification membranes. In the present work the melt spun (Ni0.6Nb0.4-yTay)100-xZrx with y=0, 0.1 and x=20, 30 was studied. Our result of X-ray diffraction spectra of the ribbons showed an amorphous nature of the alloys. Heating these ribbons below T < 400 °C, even in a hydrogen atmosphere (1-10 bar), the amorphous structure was retained. Furthermore, the crystallization process was characterized by differential thermal analysis and the activation energy of such process was obtained. The hydrogen absorption properties of the samples in their amorphous state were studied by the volumetric method, andmore » the results showed that the addition of Ta did not significantly influence the absorption properties, a clear change of the hydrogen solubility was observed with the variation of the Zr content. The values of the hydrogenation enthalpy changed from ~37 kJ/mol for x=30 to ~9 kJ/mol for x=20. Our analysis of the volumetric data provides the indications about the hydrogen occupation sites during hydrogenation, suggesting that at the beginning of the absorption process the deepest energy levels are occupied, while only shallower energy levels are available at higher hydrogen content, with the available interstitial sites forming a continuum of energy levels.« less

  20. Characteristic features of optical absorption for Gd2O3 and NiO nanoparticles

    NASA Astrophysics Data System (ADS)

    Zatsepin, A. F.; Kuznetsova, Yu. A.; Rychkov, V. N.; Sokolov, V. I.

    2017-03-01

    The technical approach to determination of the structural and optical parameters of oxides with reduced dimensionality based on optical absorption measurements is described by example of gadolinium and nickel oxides. It was established that the temperature behavior of fundamental absorption edge for oxide nanoparticles is similar with the bulk materials with crystal structure. At the same time, the energy characteristics (band gap and effective phonon energies) for low-dimensional oxides are found to be significantly different from their bulk counterparts. The presented methodological method to obtain of qualitative and quantitative correlations of structural and optical characteristics provides novel reliable knowledge of nanoscaled 3d and 4f-metal oxide materials that is useful for development of their practical applications.

  1. Combustion characteristics of hydrogen. Carbon monoxide based gaseous fuels

    NASA Technical Reports Server (NTRS)

    Notardonato, J. J.; White, D. J.; Kubasco, A. J.; Lecren, R. T.

    1981-01-01

    An experimental rig program was conducted with the objective of evaluating the combuston performance of a family of fuel gases based on a mixture of hydrogen and carbon monoxide. These gases, in addition to being members of a family, were also representative of those secondary fuels that could be produced from coal by various gasification schemes. In particular, simulated Winkler, Lurgi, and Blue-water low and medium energy content gases were used as fuels in the experimental combustor rig. The combustor used was originally designed as a low NOx rich-lean system for burning liquid fuels with high bound nitrogen levels. When used with the above gaseous fuels this combustor was operated in a lean-lean mode with ultra long residence times. The Blue-water gas was also operated in a rich-lean mode. The results of these tests indicate the possibility of the existence of an 'optimum' gas turbine hydrogen - carbon monoxide based secondary fuel. Such a fuel would exhibit NOx and high efficiency over the entire engine operating range. It would also have sufficient stability range to allow normal light-off and engine acceleration. Solar Turbines Incorporated would like to emphasize that the results presented here have been obtained with experimental rig combustors. The technologies generated could, however, be utilized in future commercial gas turbines.

  2. Combustion characteristics of hydrogen. Carbon monoxide based gaseous fuels

    NASA Astrophysics Data System (ADS)

    Notardonato, J. J.; White, D. J.; Kubasco, A. J.; Lecren, R. T.

    1981-10-01

    An experimental rig program was conducted with the objective of evaluating the combuston performance of a family of fuel gases based on a mixture of hydrogen and carbon monoxide. These gases, in addition to being members of a family, were also representative of those secondary fuels that could be produced from coal by various gasification schemes. In particular, simulated Winkler, Lurgi, and Blue-water low and medium energy content gases were used as fuels in the experimental combustor rig. The combustor used was originally designed as a low NOx rich-lean system for burning liquid fuels with high bound nitrogen levels. When used with the above gaseous fuels this combustor was operated in a lean-lean mode with ultra long residence times. The Blue-water gas was also operated in a rich-lean mode. The results of these tests indicate the possibility of the existence of an 'optimum' gas turbine hydrogen - carbon monoxide based secondary fuel. Such a fuel would exhibit NOx and high efficiency over the entire engine operating range. It would also have sufficient stability range to allow normal light-off and engine acceleration. Solar Turbines Incorporated would like to emphasize that the results presented here have been obtained with experimental rig combustors. The technologies generated could, however, be utilized in future commercial gas turbines.

  3. Hydrogen sensing characteristics of semipolar (112{sup ¯}2) GaN Schottky diodes

    SciTech Connect

    Hyeon Baik, Kwang; Kim, Hyonwoong; Jang, Soohwan; Lee, Sung-Nam; Lim, Eunju; Pearton, S. J.; Ren, F.

    2014-02-17

    The hydrogen detection characteristics of semipolar (112{sup ¯}2) plane GaN Schottky diodes were investigated and compared to c-plane Ga- and N-polar and nonpolar a-plane (112{sup ¯}0) GaN diodes. The semipolar GaN diodes showed large current response to 4% hydrogen in nitrogen gas with an accompanying Schottky barrier reduction of 0.53 eV at 25 °C, and the devices exhibited full recovery to the initial current level upon switching to a nitrogen ambient. The current-voltage characteristics of the semipolar devices remained rectifying after hydrogen exposure, in sharp contrast to the case of c-plane N-polar GaN. These results show that the surface atom configuration and polarity play a strong role in hydrogen sensing with GaN.

  4. The hydrogen-poor superluminous supernova iPTF 13ajg and its host galaxy in absorption and emission

    SciTech Connect

    Vreeswijk, Paul M.; Gal-Yam, Avishay; De Cia, Annalisa; Rubin, Adam; Yaron, Ofer; Tal, David; Ofek, Eran O.; Savaglio, Sandra; Quimby, Robert M.; Sullivan, Mark; Cenko, S. Bradley; Filippenko, Alexei V.; Clubb, Kelsey I.; Perley, Daniel A.; Cao, Yi; Taddia, Francesco; Sollerman, Jesper; Leloudas, Giorgos; Arcavi, Iair; Kasliwal, Mansi M.; and others

    2014-12-10

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory, iPTF 13ajg. At a redshift of z = 0.7403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude of M {sub u,} {sub AB} = –22.5, one of the most luminous supernovae to date. The observed bolometric peak luminosity of iPTF 13ajg is 3.2 × 10{sup 44} erg s{sup –1}, while the estimated total radiated energy is 1.3 × 10{sup 51} erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the Very Large Telescope. From Voigt profile fitting, we derive the column densities log N(Mg I) =11.94 ± 0.06, log N(Mg II) =14.7 ± 0.3, and log N(Fe II) =14.25 ± 0.10. These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs) whose progenitors are also thought to be massive stars. This suggests that the environments of hydrogen-poor SLSNe and GRBs are different. From the nondetection of Fe II fine-structure absorption lines, we derive a lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc. The neutral gas responsible for the absorption in iPTF 13ajg exhibits a single narrow component with a low velocity width, ΔV = 76 km s{sup –1}, indicating a low-mass host galaxy. No host galaxy emission lines are detected, leading to an upper limit on the unobscured star formation rate (SFR) of SFR{sub [O} {sub II]}<0.07M{sub ⊙}yr{sup −1}. Late-time imaging shows the iPTF 13ajg host galaxy to be faint, with g {sub AB} ≈ 27.0 and R {sub AB} ≥ 26.0 mag, corresponding to M {sub B,} {sub Vega} ≳ –17.7 mag.

  5. The Hydrogen-poor Superluminous Supernova iPTF 13ajg and its Host Galaxy in Absorption and Emission

    NASA Astrophysics Data System (ADS)

    Vreeswijk, Paul M.; Savaglio, Sandra; Gal-Yam, Avishay; De Cia, Annalisa; Quimby, Robert M.; Sullivan, Mark; Cenko, S. Bradley; Perley, Daniel A.; Filippenko, Alexei V.; Clubb, Kelsey I.; Taddia, Francesco; Sollerman, Jesper; Leloudas, Giorgos; Arcavi, Iair; Rubin, Adam; Kasliwal, Mansi M.; Cao, Yi; Yaron, Ofer; Tal, David; Ofek, Eran O.; Capone, John; Kutyrev, Alexander S.; Toy, Vicki; Nugent, Peter E.; Laher, Russ; Surace, Jason; Kulkarni, Shrinivas R.

    2014-12-01

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory, iPTF 13ajg. At a redshift of z = 0.7403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude of M u, AB = -22.5, one of the most luminous supernovae to date. The observed bolometric peak luminosity of iPTF 13ajg is 3.2 × 1044 erg s-1, while the estimated total radiated energy is 1.3 × 1051 erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the Very Large Telescope. From Voigt profile fitting, we derive the column densities log N(Mg I) =11.94 ± 0.06, log N(Mg II) =14.7 ± 0.3, and log N(Fe II) =14.25 ± 0.10. These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs) whose progenitors are also thought to be massive stars. This suggests that the environments of hydrogen-poor SLSNe and GRBs are different. From the nondetection of Fe II fine-structure absorption lines, we derive a lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc. The neutral gas responsible for the absorption in iPTF 13ajg exhibits a single narrow component with a low velocity width, ΔV = 76 km s-1, indicating a low-mass host galaxy. No host galaxy emission lines are detected, leading to an upper limit on the unobscured star formation rate (SFR) of SFR_[O \\scriptsize{II]}<0.07 {M_⊙ yr-1}. Late-time imaging shows the iPTF 13ajg host galaxy to be faint, with g AB ≈ 27.0 and R AB >= 26.0 mag, corresponding to M B, Vega >~ -17.7 mag.

  6. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    DOEpatents

    Wang, Jia X [East Setauket, NY; Adzic, Radoslav R [East Setauket, NY

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  7. Absorption fever characteristics due to percutaneous renal biopsy-related hematoma.

    PubMed

    Hu, Tingyang; Liu, Qingquan; Xu, Qin; Liu, Hui; Feng, Yan; Qiu, Wenhui; Huang, Fei; Lv, Yongman

    2016-09-01

    This study aims to describe the unique characteristics of absorption fever in patients with a hematoma after percutaneous renal biopsy (PRB) and distinguish it from secondary infection of hematoma.We retrospectively studied 2639 percutaneous renal biopsies of native kidneys. We compared the clinical characteristics between 2 groups: complication group (gross hematuria and/or perirenal hematoma) and no complication group. The axillary temperature of patients with a hematoma who presented with fever was measured at 06:00, 10:00, 14:00, and 18:00. The onset and duration of fever and the highest body temperature were recorded. Thereafter, we described the time distribution of absorption fever and obtained the curve of fever pattern.Of 2639 patients, PRB complications were observed in 154 (5.8%) patients. Perirenal hematoma was the most common complication, which occurred in 118 (4.5%) of biopsies, including 74 small hematoma cases (thickness ≤3 cm) and 44 large hematoma cases (thickness >3 cm). Major complications were observed in only 6 (0.2%) cases resulting from a large hematoma. Of 118 patients with a perirenal hematoma, absorption fever was observed in 48 cases. Furthermore, large hematomas had a 5.23-fold higher risk for absorption fever than the small ones.Blood pressure, renal insufficiency, and prothrombin time could be risk factors for complications. Fever is common in patients with hematoma because of renal biopsy and is usually noninfectious. Evaluation of patients with post-biopsy fever is necessary to identify any obvious infection sources. If no focus is identified, empiric antibiotic therapy should not be initiated nor should prophylactic antibiotics be extended for prolonged durations. Absorption fevers will resolve in time without specific therapeutic interventions.

  8. Absorption fever characteristics due to percutaneous renal biopsy-related hematoma

    PubMed Central

    Hu, Tingyang; Liu, Qingquan; Xu, Qin; Liu, Hui; Feng, Yan; Qiu, Wenhui; Huang, Fei; Lv, Yongman

    2016-01-01

    Abstract This study aims to describe the unique characteristics of absorption fever in patients with a hematoma after percutaneous renal biopsy (PRB) and distinguish it from secondary infection of hematoma. We retrospectively studied 2639 percutaneous renal biopsies of native kidneys. We compared the clinical characteristics between 2 groups: complication group (gross hematuria and/or perirenal hematoma) and no complication group. The axillary temperature of patients with a hematoma who presented with fever was measured at 06:00, 10:00, 14:00, and 18:00. The onset and duration of fever and the highest body temperature were recorded. Thereafter, we described the time distribution of absorption fever and obtained the curve of fever pattern. Of 2639 patients, PRB complications were observed in 154 (5.8%) patients. Perirenal hematoma was the most common complication, which occurred in 118 (4.5%) of biopsies, including 74 small hematoma cases (thickness ≤3 cm) and 44 large hematoma cases (thickness >3 cm). Major complications were observed in only 6 (0.2%) cases resulting from a large hematoma. Of 118 patients with a perirenal hematoma, absorption fever was observed in 48 cases. Furthermore, large hematomas had a 5.23-fold higher risk for absorption fever than the small ones. Blood pressure, renal insufficiency, and prothrombin time could be risk factors for complications. Fever is common in patients with hematoma because of renal biopsy and is usually noninfectious. Evaluation of patients with post-biopsy fever is necessary to identify any obvious infection sources. If no focus is identified, empiric antibiotic therapy should not be initiated nor should prophylactic antibiotics be extended for prolonged durations. Absorption fevers will resolve in time without specific therapeutic interventions. PMID:27631225

  9. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics

    NASA Astrophysics Data System (ADS)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki

    2009-09-01

    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  10. Determination of trace nickel in hydrogenated cottonseed oil by electrothermal atomic absorption spectrometry after microwave-assisted digestion.

    PubMed

    Zhang, Gai

    2012-01-01

    Microwave digestion of hydrogenated cottonseed oil prior to trace nickel determination by electrothermal atomic absorption spectrometry (ETAAS) is proposed here for the first time. Currently, the methods outlined in U.S. Pharmacopeia 28 (USP28) or British Pharmacopeia (BP2003) are recommended as the official methods for analyzing nickel in hydrogenated cottonseed oil. With these methods the samples may be pre-treated by a silica or a platinum crucible. However, the samples were easily tarnished during sample pretreatment when using a silica crucible. In contrast, when using a platinum crucible, hydrogenated cottonseed oil acting as a reducing material may react with the platinum and destroy the crucible. The proposed microwave-assisted digestion avoided tarnishing of sample in the process of sample pretreatment and also reduced the cycle of analysis. The programs of microwave digestion and the parameters of ETAAS were optimized. The accuracy of the proposed method was investigated by analyzing real samples. The results were compared with the ones by pressurized-PTFE-bomb acid digestion and ones obtained by the U.S. Pharmacopeia 28 (USP28) method. The new method involves a relatively rapid matrix destruction technique compared with other present methods for the quantification of metals in oil. © 2011 Institute of Food Technologists®

  11. On the formation and ordering of ``superabundant`` vacancies in palladium due to hydrogen absorption

    SciTech Connect

    Oates, W.A.; Wenzl, H.

    1995-07-15

    The formation of superabundant vacancies in metals can be driven by hydrogen incorporation on the interstitial sublattice. In order to achieve this, it is essential to have a sufficiently high hydrogen chemical potential so that effectively all the available interstitial sites are occupied. The concomitant formation of high concentrations of vacancies on the metal sublattice is then controlled by the coupling of the vacancy chemical potentials on the metal and interstitial sublattices by the Schottky equilibrium condition. This formation of excessive concentrations of vacancies on the host metal lattice is expected to be a general phenomenon which, if the system can achieve vacancy equilibrium with external or internal sinks, will occur as soon as the interstitial sublattice approaches complete filling. This means that the hydrogen/metal ratio will exceed that normally expected for a complete filling of the interstitial sites being considered. Once a high concentration of vacancies has been formed, then an effective repulsive interaction between the vacancies on the metal sublattice may give rise to vacancy ordering at lower temperatures. This interpretation is in good agreement with the experimental results of Fukai and Okuma for the Pd-H system. The authors estimate that they have reached a hydrogen/metal ratio of {approx} 1.2, which they have shown to be quite feasible at the H{sub 2}(g) pressures and temperatures used in their experiments.

  12. Enhanced absorption in tandem solar cells by applying hydrogenated In{sub 2}O{sub 3} as electrode

    SciTech Connect

    Yin, Guanchao Manley, Phillip; Steigert, Alexander; Klenk, Reiner; Schmid, Martina

    2015-11-23

    To realize the high efficiency potential of perovskite/chalcopyrite tandem solar cells in modules, hydrogenated In{sub 2}O{sub 3} (IO:H) as electrode is investigated. IO:H with an electron mobility of 100 cm{sup 2} V{sup −1} s{sup −1} is demonstrated. Compared to the conventional Sn doped In{sub 2}O{sub 3} (ITO), IO:H exhibits a decreased electron concentration and leads to almost no sub-bandgap absorption up to the wavelength of 1200 nm. Without a trade-off between transparency and lateral resistance in the IO:H electrode, the tandem cell keeps increasing in efficiency as the IO:H thickness increases and efficiencies above 22% are calculated. In contrast, the cells with ITO as electrode perform much worse due to the severe parasitic absorption in ITO. This indicates that IO:H has the potential to lead to high efficiencies, which is otherwise constrained by the parasitic absorption in conventional transparent conductive oxide electrode for tandem solar cells in modules.

  13. Correlating Infrared and X-ray Absorption Energies for Molecular-Level Insight into Hydrogen Bond Making and Breaking in Solution.

    PubMed

    Prémont-Schwarz, Mirabelle; Schreck, Simon; Iannuzzi, Marcella; Nibbering, Erik T J; Odelius, Michael; Wernet, Philippe

    2015-06-25

    While ubiquitous, the making and breaking of hydrogen bonds in solution is notoriously difficult to study due to the associated complex changes of nuclear and electronic structures. With the aim to reduce the according uncertainty in correlating experimental observables and hydrogen-bond configurations, we combine the information from proximate methods to study the N-H···O hydrogen bond in solution. We investigate hydrogen-bonding of the N-H group of N-methylaniline with oxygen from liquid DMSO and acetone with infrared spectra in the N-H stretching region and X-ray absorption spectra at the N K-edge. We experimentally observe blue shifts of the infrared stretching band and an X-ray absorption pre-edge peak when going from DMSO to acetone. With ab initio molecular dynamics simulations and calculated spectra, we qualitatively reproduce the experimental observables but we do not reach quantitative agreement with experiment. The infrared spectra support the notion of weakening the N-H···O hydrogen bond from DMSO to acetone. However, we fail to theoretically reproduce the measured shift of the X-ray absorption pre-edge peak. We discuss possible shortcomings of the simulation models and spectrum calculations. Common features and distinct differences with the O-H···O hydrogen bond are highlighted, and the implications for monitoring hydrogen-bond breaking in solution are discussed.

  14. Hydrogen absorption in uranium-based alloys with cubic γ -U structure

    NASA Astrophysics Data System (ADS)

    Havela, L.; Kim-Ngan, N.-T. H.

    2017-03-01

    UH3-type hydrides were formed by hydrogenation of splat-cooled U-based alloys upon applying high H2 pressures (>2.5 bar). Hydrogenation of U1-x Mo x alloys (with x  ⩾  0.12 (12 at.% Mo) containing the cubic γ-U phase leads to a formation of nanocrystalline β-UH3, why those of U1-x Zr x alloys (with x  ⩾15 at.% Zr) implies a pure α-UH3. The Curie temperature of hydride (UH3)0.85Mo0.15 reaches 200 K it may be the first U-based ferromagnet with such high T C. The results reflect the dominant U-H interaction. Invited talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

  15. Solar energy absorption characteristics and the effects of heat on the optical properties of several coatings

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1981-01-01

    The solar energy absorption characteristics of several high temperature coatings were determined and effects of heat on these coatings were evaluated. Included in the investigation were an electroplated alloy of black chrome and vanadium, electroplated black chrome, and chemically colored 316 stainless steel. Each of the coatings possessed good selective solar energy absorption properties at laboratory ambient temperature. Measured at a temperature of 700 K (800 F), the emittances of black chrome, black chrome vanadium, and colored stainless steel were 0.11, 0.61, and 0.15, respectively. Black chrome and black chrome vanadium did not degrade optically in the presence of high heat (811 K (1000 F)). Chemically colored stainless steel showed slight optical degradation when exposed to moderately high heat (616 K (650 F)0, but showed more severe degradation at exposure temperatures beyond this level. Each of the coatings showed good corrosion resistance to a salt spray environment.

  16. Study on the Partial Load Characteristics of Double-Effect Absorption Systems

    NASA Astrophysics Data System (ADS)

    Kawakami, Ryuichiro; Fukuchi, Toru; Kaita, Yoshio

    Simulation analysis was carried out to study the partial load characteristics of three different types of double-effect LiBr-water absorption cycle, namely series flow, parallel flow and reverse flow. A computer program was developed for this study to simulate the behavior of the absorption cycles equipped with flow rate control of absorbent, cooling water and chilling water on partial load. The effects of the flow rate control on the coefficient of performance (COP), the maximum temperature and maximum pressure were studied. The results show that not only flow rate control of absorbent is essential for high COP on the partial load, but also flow rate control of cooling water and chilling water is recommendable to save the power of pumping.

  17. Influence of drug physicochemical characteristics on in vitro transdermal absorption of hydrophobic drug nanosuspensions.

    PubMed

    Shen, Cheng-Ying; Li, Rui-Sheng; Shen, Bao-de; Shen, Gang; Wang, Li-Qiang; Zheng, Juan; Li, Xiao-Rong; Min, Hong-Yan; Han, Jin; Yuan, Hai-Long

    2015-01-01

    The purpose of this paper was to study the influence of drug physicochemical characteristics on in vitro transdermal absorption of hydrophobic drug nanosuspensions. Four drug nanosuspensions were produced by high-pressure homogenization technique, which were the same in stabilizer and similar in particle size. Differential scanning calorimetry and powder X-ray diffraction analysis showed that the crystalline state of the nanocrystals did not change. In vitro permeation study demonstrated that the drug nanosuspensions have a higher rate of permeation that ranged from 1.69- to 3.74-fold compared to drug microsuspensions. Correlation analysis between drug physicochemical properties and Jss revealed that log P and pKa were factors that influenced the in vitro transdermal absorption of hydrophobic drug nanosuspensions, and drugs with a log P value around 3 and a higher pKa value (when pKa < pH+2) would gain higher Jss in this paper.

  18. Moisture absorption and bakeout characteristics of rigid-flexible multilayer printed wiring boards

    SciTech Connect

    Lula, J.W.

    1991-01-01

    Moisture absorption and bakeout characteristics of Allied-Signal Inc., Kansas City Division (KCD) rigid-flexible printed wiring boards were determined. It was found that test specimens had absorbed 0.95 weight percent moisture when equilibrated to a 50 percent RH, 25{degree}C environment. Heating those equilibrated specimens in a 120{degree}C static air oven removed 92 percent of this absorbed moisture in 24 h. Heating the samples in a 80{degree}C static air oven removed only 64 percent of the absorbed moisture at the end of 24 h. A 120{degree}C vacuum bake removed moisture at essentially the same rate with parylene slowed the absorption rate by approximately 50 percent but did not appreciably affect the equilibrium moisture content or the drying rate.

  19. Solar absorption characteristics of several coatings and surface finishes. [for solar energy collectors

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1977-01-01

    Solar absorption characteristics are established for several films potentially favorable for use as receiving surfaces in solar energy collectors. Included in the investigation were chemically produced black films, black electrodeposits, and anodized coatings. It was found that black nickel exhibited the best combination of selective optical properties of any of the coatings studied. A serious drawback to black nickel was its high susceptibility to degradation in the presence of high moisture environments. Electroplated black chrome generally exhibited high solar absorptivities, but the emissivity varied considerably and was also relatively high under some conditions. The black chrome had the greatest moisture resistance of any of the coatings tested. Black oxide coatings on copper and steel substrates showed the best combination of selective optical properties of any of the chemical conversion films studied.

  20. The Ternary Gallide CeNiGa: Polymorphism and Hydrogen Absorption

    NASA Astrophysics Data System (ADS)

    Chevalier, B.; Bobet, J.-L.; Gaudin, E.; Pasturel, M.; Etourneau, J.

    2002-10-01

    The ternary gallide CeNiGa presents a crystallographic transformation with temperature. The crystal structure of the high-temperature form (HTF), determined for the first time by X-ray diffraction on a single crystal, is orthorhombic TiNiSi-type, whereas the low-temperature form (LTF) adopts the hexagonal ZrNiAl-type. Electrical resistivity and magnetization measurements reveal that both (LTF) and (HTF) CeNiGa are classified as intermediate valence compounds, but their Kondo temperatures TK are strongly different; TK≫300 K and TK≅95(5) K for (LTF) and (HTF), respectively. Both forms react with hydrogen at room temperature and form the hydride CeNiGaH 1.1(1) which crystallizes in the hexagonal AlB 2-type with lattice parameters a=4.239(4) Å and c=4.258(5) Å. Hydrogenation also induces a valence transition for cerium from the intermediate valence state (CeNiGa) to a purely trivalent state (CeNiGaH 1.1(1)). This behavior is correlated to an increase of the unit cell volume after hydrogenation and is compared to that observed previously for CeNiAlH 1.93.

  1. Physiological characteristics of the extreme thermophile Caldicellulosiruptor saccharolyticus: an efficient hydrogen cell factory

    PubMed Central

    2010-01-01

    Global concerns about climate changes and their association with the use of fossil fuels have accelerated research on biological fuel production. Biological hydrogen production from hemicellulose-containing waste is considered one of the promising avenues. A major economical issue for such a process, however, is the low substrate conversion efficiency. Interestingly, the extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus can produce hydrogen from carbohydrate-rich substrates at yields close to the theoretical maximum of the dark fermentation process (i.e., 4 mol H2/mol hexose). The organism is able to ferment an array of mono-, di- and polysaccharides, and is relatively tolerant to high partial hydrogen pressures, making it a promising candidate for exploitation in a biohydrogen process. The behaviour of this Gram-positive bacterium bears all hallmarks of being adapted to an environment sparse in free sugars, which is further reflected in its low volumetric hydrogen productivity and low osmotolerance. These two properties need to be improved by at least a factor of 10 and 5, respectively, for a cost-effective industrial process. In this review, the physiological characteristics of C. saccharolyticus are analyzed in view of the requirements for an efficient hydrogen cell factory. A special emphasis is put on the tight regulation of hydrogen production in C. saccharolyticus by both redox and energy metabolism. Suggestions for strategies to overcome the current challenges facing the potential use of the organism in hydrogen production are also discussed. PMID:21092203

  2. Operational characteristics of the J-PARC cryogenic hydrogen system for a spallation neutron source

    SciTech Connect

    Tatsumoto, Hideki; Ohtsu, Kiichi; Aso, Tomokazu; Kawakami, Yoshihiko; Teshigawara, Makoto

    2014-01-29

    The J-PARC cryogenic hydrogen system provides supercritical hydrogen with the para-hydrogen concentration of more than 99 % and the temperature of less than 20 K to three moderators so as to provide cold pulsed neutron beams of a higher neutronic performance. Furthermore, the temperature fluctuation of the feed hydrogen stream is required to be within ± 0.25 K. A stable 300-kW proton beam operation has been carried out since November 2012. The para-hydrogen concentrations were measured during the cool-down process. It is confirmed that para-hydrogen always exists in the equilibrium concentration because of the installation of an ortho-para hydrogen convertor. Propagation characteristics of temperature fluctuation were measured by temporarily changing the heater power under off-beam condition to clarify the effects of a heater control for thermal compensation on the feed temperature fluctuation. The experimental data gave an allowable temperature fluctuation of ± 1.05 K. It is clarified through a 286-kW and a 524-kW proton beam operations that the heater control would be applicable for the 1-MW proton beam operation by extrapolating from the experimental data.

  3. Application of CFRP with High Hydrogen Gas Barrier Characteristics to Fuel Tanks of Space Transportation System

    NASA Astrophysics Data System (ADS)

    Yonemoto, Koichi; Yamamoto, Yuta; Okuyama, Keiichi; Ebina, Takeo

    In the future, carbon fiber reinforced plastics (CFRPs) with high hydrogen gas barrier performance will find wide applications in all industrial hydrogen tanks that aim at weight reduction; the use of such materials will be preferred to the use of conventional metallic materials such as stainless steel or aluminum. The hydrogen gas barrier performance of CFRP will become an important issue with the introduction of hydrogen-fuel aircraft. It will also play an important role in realizing fully reusable space transportation system that will have high specific tensile CFRP structures. Such materials are also required for the manufacture of high-pressure hydrogen gas vessels for use in the fuel cell systems of automobiles. This paper introduces a new composite concept that can be used to realize CFRPs with high hydrogen gas barrier performance for applications in the cryogenic tanks of fully reusable space transportation system by the incorporation of a nonmetallic crystal layer, which is actually a dense and highly oriented clay crystal laminate. The preliminary test results show that the hydrogen gas barrier characteristics of this material after cryogenic heat shocks and cyclic loads are still better than those of other polymer materials by approximately two orders of magnitude.

  4. Coupled optical absorption, charge carrier separation, and surface electrochemistry in surface disordered/hydrogenated TiO2 for enhanced PEC water splitting reaction.

    PubMed

    Behara, Dilip Kumar; Ummireddi, Ashok Kumar; Aragonda, Vidyasagar; Gupta, Prashant Kumar; Pala, Raj Ganesh S; Sivakumar, Sri

    2016-03-28

    The central governing factors that influence the efficiency of photoelectrochemical (PEC) water splitting reaction are photon absorption, effective charge-carrier separation, and surface electrochemistry. Attempts to improve one of the three factors may debilitate other factors and we explore such issues in hydrogenated TiO2, wherein a significant increase in optical absorption has not resulted in a significant increase in PEC performance, which we attribute to the enhanced recombination rate due to the formation of amorphization/disorderness in the bulk during the hydrogenation process. To this end, we report a methodology to increase the charge-carrier separation with enhanced optical absorption of hydrogenated TiO2. Current methodology involves hydrogenation of non-metal (N and S) doped TiO2 which comprises (1) lowering of the band gap through shifting of the valence band via less electronegative non-metal N, S-doping, (2) lowering of the conduction band level and the band gap via formation of the Ti(3+) state and oxygen vacancies by hydrogenation, and (3) material processing to obtain a disordered surface structure which favors higher electrocatalytic (EC) activity. This design strategy yields enhanced PEC activity (%ABPE = 0.38) for the N-S co-doped TiO2 sample hydrogenated at 800 °C for 24 h over possible combinations of N-S co-doped TiO2 samples hydrogenated at 500 °C/24 h, 650 °C/24 h and 800 °C/72 h. This suggests that hydrogenation at lower temperatures does not result in much increase in optical absorption and prolonged hydrogenation results in an increase in optical absorption but a decrease in charge carrier separation by forming disorderness/oxygen vacancies in the bulk. Furthermore, the difference in double layer capacitance (C(dl)) calculated from electrochemical impedance spectroscopy (EIS) measurements of these samples reflects the change in the electrochemical surface area (ECSA) and facilitates assessing the key role of surface

  5. Sensitive absorption measurements of hydrogen sulfide at 1.578 μm using wavelength modulation spectroscopy

    NASA Astrophysics Data System (ADS)

    Xia, Hua; Dong, Feng-Zhong; Wu, Bian; Zhang, Zhi-Rong; Pang, Tao; Sun, Peng-Shuai; Cui, Xiao-Juan; Han, Luo; Wang, Yu

    2015-03-01

    Sensitive detection of hydrogen sulfide (H2S) has been performed by means of wavelength modulation spectroscopy (WMS) near 1.578 μm. With the scan amplitude and the stability of the background baseline taken into account, the response time is 4 s for a 0.8 L multi-pass cell with a 56.7 m effective optical path length. Moreover, the linearity has been tested in the 0-50 ppmv range. The detection limit achievable by the Allan variance is 224 ppb within 24 s under room temperature and ambient pressure conditions. This tunable diode laser absorption spectroscopy (TDLAS) system for H2S detection has the feasibility of real-time online monitoring in many applications. Project supported by the Special Fund for Basic Research on Scientific Instruments of the Chinese Academy of Sciences (Grant No. YZ201315) and the National Natural Science Foundation of China (Grant Nos. 11204320, 41405034, and 11204319).

  6. Measured cathode fall characteristics depending on the diameter of a hydrogen hollow cathode discharge

    NASA Astrophysics Data System (ADS)

    Gonzalez-Fernandez, V.; Grützmacher, K.; Steiger, A.; Pérez, C.; de la Rosa, M. I.

    2017-10-01

    In this work, Doppler-free two photon optogalvanic spectroscopy is used to measure the electric field strength in the cathode fall region of a hollow cathode discharge, operated in pure hydrogen, via the Stark splitting of the 2S level of atomic hydrogen. The cathode fall characteristics are analysed for various pressures and in a wide range of discharge currents. Tungsten is used as the cathode material, because it allows for reliable measurements in a fairly wide range of discharge conditions and because of its minimal sputtering. Two cathode diameters (10 mm and 15 mm) are used to study the dependence of the cathode fall on discharge geometry. The measurements reveal that the cathode fall characteristics are quite independent on the cathode diameter for equal cathode current density; hence the measurements can be used to test one dimensional modelling of the cathode fall region for low pressure hydrogen discharges using e.g. plane parallel electrodes.

  7. Effects of hydrogen bonding on current-voltage characteristics of molecular junctions

    NASA Astrophysics Data System (ADS)

    Kula, Mathias; Jiang, Jun; Lu, Wei; Luo, Yi

    2006-11-01

    We present a first-principles study of hydrogen bonding effect on current-voltage characteristics of molecular junctions. Three model charge-transfer molecules, 2'-amino-4,4'-di(ethynylphenyl)-1-benzenethiolate (DEPBT-D), 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate (DEPBT-A), and 2'-amino-4,4'-di(ethynylphenyl)-5'-nitro-1-benzenethiolate (DEPBT-DA), have been examined and compared with the corresponding hydrogen bonded complexes formed with different water molecules. Large differences in current-voltage characteristics are observed for DEPBT-D and DEPBT-A molecules with or without hydrogen bonded waters, while relatively small differences are found for DEPBT-DA. It is predicted that the presence of water clusters can drastically reduce the conductivities of the charge-transfer molecules. The underlying microscopic mechanism has been discussed.

  8. Synthesis and crystal structure of a Pr5Ni19 superlattice alloy and its hydrogen absorption-desorption property.

    PubMed

    Iwase, Kenji; Sakaki, Kouji; Matsuda, Junko; Nakamura, Yumiko; Ishigaki, Toru; Akiba, Etsuo

    2011-05-16

    The intermetallic compound Pr(5)Ni(19), which is not shown in the Pr-Ni binary phase diagram, was synthesized, and the crystal structure was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Two superlattice reflections with the Sm(5)Co(19)-type structure (002 and 004) and the Pr(5)Co(19)-type structure (003 and 006) were observed in the 2θ region between 2° and 15° in the XRD pattern using Cu Kα radiation. Rietveld refinement provided the goodness-of-fit parameter S = 6.7 for the Pr(5)Co(19)-type (3R) structure model and S = 1.7 for the Sm(5)Co(19)-type (2H) structure model, indicating that the synthesized compound has a Sm(5)Co(19) structure. The refined lattice parameters were a = 0.50010(9) nm and c = 3.2420(4) nm. The high-resolution TEM image also clearly revealed that the crystal structure of Pr(5)Ni(19) is of the Sm(5)Co(19) type, which agrees with the results from Rietveld refinement of the XRD data. The P-C isotherm of Pr(5)Ni(19) in the first absorption was clearly different from that in the first desorption. A single plateau in absorption and three plateaus in desorption were observed. The maximum hydrogen storage capacity of the first cycle reached 1.1 H/M, and that of the second cycle was 0.8 H/M. The 0.3 H/M of hydrogen remained in the metal lattice after the first desorption process.

  9. A method for monitoring the variability in nuclear absorption characteristics of aviation fuels

    NASA Technical Reports Server (NTRS)

    Sprinkle, Danny R.; Shen, Chih-Ping

    1988-01-01

    A technique for monitoring variability in the nuclear absorption characteristics of aviation fuels has been developed. It is based on a highly collimated low energy gamma radiation source and a sodium iodide counter. The source and the counter assembly are separated by a geometrically well-defined test fuel cell. A computer program for determining the mass attenuation coefficient of the test fuel sample, based on the data acquired for a preset counting period, has been developed and tested on several types of aviation fuel.

  10. Electrochromic poly(acetylene)s with switchable visible/near-IR absorption characteristics.

    PubMed

    Pauly, Anja C; Varnado, C Daniel; Bielawski, Christopher W; Theato, Patrick

    2014-01-01

    Ferrocene is incorporated into a poly(acetylene) derivative via the postpolymerization amidation of a polymer precursor bearing pentafluorophenyl ester-leaving groups with aminoferrocene. While the neutral polymer exhibits a strong absorbance at 553 nm due to its conjugated backbone, oxidation of the ferrocene moieties with silver tetrafluoroborate causes the material to absorb in the near-IR (λ max ≈ 1215 nm). Subsequent reduction of the oxidized polymer with decamethylferrocene restores the initial absorbance profile, demonstrating that the material features switchable visible/near-IR absorption characteristics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Combustion characteristics of hydrogen-carbon monoxide based gaseous fuels

    NASA Technical Reports Server (NTRS)

    White, D. J.; Kubasco, A. J.; Lecren, R. T.; Notardonato, J. J.

    1982-01-01

    The results of trials with a staged combustor designed to use coal-derived gaseous fuels and reduce the NO(x) emissions from nitrogen-bound fuels to 75 ppm and 37 ppm without bound nitrogen in 15% O2 are reported. The combustor was outfitted with primary zone regenerative cooling, wherein the air cooling the primary zone was passed into the combustor at 900 F and mixed with the fuel. The increase in the primary air inlet temperature eliminated flashback and autoignition, lowered the levels of CO, unburned hydrocarbons, and smoke, and kept combustion efficiencies to the 99% level. The combustor was also equipped with dual fuel injection to test various combinations of liquid/gas fuel mixtures. Low NO(x) emissions were produced burning both Lurgi and Winkler gases, regardless of the inlet pressure and temperature conditions. Evaluation of methanation of medium energy gases is recommended for providing a fuel with low NO(x) characteristics.

  12. Combustion characteristics of hydrogen-carbon monoxide based gaseous fuels

    NASA Technical Reports Server (NTRS)

    White, D. J.; Kubasco, A. J.; Lecren, R. T.; Notardonato, J. J.

    1982-01-01

    The results of trials with a staged combustor designed to use coal-derived gaseous fuels and reduce the NO(x) emissions from nitrogen-bound fuels to 75 ppm and 37 ppm without bound nitrogen in 15% O2 are reported. The combustor was outfitted with primary zone regenerative cooling, wherein the air cooling the primary zone was passed into the combustor at 900 F and mixed with the fuel. The increase in the primary air inlet temperature eliminated flashback and autoignition, lowered the levels of CO, unburned hydrocarbons, and smoke, and kept combustion efficiencies to the 99% level. The combustor was also equipped with dual fuel injection to test various combinations of liquid/gas fuel mixtures. Low NO(x) emissions were produced burning both Lurgi and Winkler gases, regardless of the inlet pressure and temperature conditions. Evaluation of methanation of medium energy gases is recommended for providing a fuel with low NO(x) characteristics.

  13. Some characteristics of new type of hydrogen maser receiver in Shaanxi Astronomical Observatory.

    NASA Astrophysics Data System (ADS)

    Ren, Yan

    1990-12-01

    Some characteristics of the new type of hydrogen maser receiver in Shaanxi Astronomical Observatory are described, and the methods of noise rejection are presented in detail. The measured results show that the stability is 1.8×10-13s-1.

  14. Recent Advances in SRS on Hydrogen Isotope Separation Using Thermal Cycling Absorption Process

    DOE PAGES

    Xiao, Xin; Sessions, Henry T.; Heung, L. Kit

    2015-02-01

    The recent Thermal Cycling Absorption Process (TCAP) advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10th of the current production system’s footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects and medical isotope production.

  15. Recent Advances in SRS on Hydrogen Isotope Separation Using Thermal Cycling Absorption Process

    SciTech Connect

    Xiao, Xin; Sessions, Henry T.; Heung, L. Kit

    2015-02-01

    The recent Thermal Cycling Absorption Process (TCAP) advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10th of the current production system’s footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects and medical isotope production.

  16. The interstellar deuterium-to-hydrogen ratio - A reevaluation of Lyman absorption-line measurements

    NASA Technical Reports Server (NTRS)

    Mccullough, Peter R.

    1992-01-01

    The D/H ratio in the local interstellar medium is evaluated based upon previously published measurements of Lyman absorption lines together with the hypothesis that the D/H ratio is constant. A unique value for the D/H ratio of 1.5 (+/- 0.2) x 10 exp -5 by number is shown to be consistent with all published determinations made with the Copernicus and the International Ultraviolet Explorer satellites. The possibility that the D/H ratio may vary substantially in the local interstellar medium is considered and found to be unnecessary.

  17. Ultraviolet Absorption Induces Hydrogen-Atom Transfer in G⋅C Watson-Crick DNA Base Pairs in Solution.

    PubMed

    Röttger, Katharina; Marroux, Hugo J B; Grubb, Michael P; Coulter, Philip M; Böhnke, Hendrik; Henderson, Alexander S; Galan, M Carmen; Temps, Friedrich; Orr-Ewing, Andrew J; Roberts, Gareth M

    2015-12-01

    Ultrafast deactivation pathways bestow photostability on nucleobases and hence preserve the structural integrity of DNA following absorption of ultraviolet (UV) radiation. One controversial recovery mechanism proposed to account for this photostability involves electron-driven proton transfer (EDPT) in Watson-Crick base pairs. The first direct observation is reported of the EDPT process after UV excitation of individual guanine-cytosine (G⋅C) Watson-Crick base pairs by ultrafast time-resolved UV/visible and mid-infrared spectroscopy. The formation of an intermediate biradical species (G[-H]⋅C[+H]) with a lifetime of 2.9 ps was tracked. The majority of these biradicals return to the original G⋅C Watson-Crick pairs, but up to 10% of the initially excited molecules instead form a stable photoproduct G*⋅C* that has undergone double hydrogen-atom transfer. The observation of these sequential EDPT mechanisms across intermolecular hydrogen bonds confirms an important and long debated pathway for the deactivation of photoexcited base pairs, with possible implications for the UV photochemistry of DNA.

  18. Temperature dependences of line widths and peak positions of optical absorption peaks due to localized vibration of hydrogen Si

    NASA Astrophysics Data System (ADS)

    Suezawa, M.; Fukata, N.; Saito, M.; Yamada-Kaneta, H.

    2001-12-01

    We studied the temperature dependences of line widths and peak positions of optical absorptions due to the hydrogen bound to point defects and acceptors in Si. Specimens were prepared from floating-zone-grown Si crystals of high-purity and of p-type, doped with group III acceptors. They were doped with H by heating at 1300°C in H 2 gas followed by quenching. The former specimen was then irradiated with 3 MeV electrons at RT to form complexes of H and point defects and the latter specimens were annealed at 150°C to form H-acceptor pairs. We measured their optical absorption spectra by an FT-IR spectrometer in the temperature range of 6 K and RT. Peaks due to localized vibrational modes of H bound to acceptors and point defects were well fitted with Lorentzian line shapes. The temperature dependences of those line widths and peak positions were analyzed with the dephasing model proposed by Persson and Ryberg.

  19. Annealing characteristics of irradiated hydrogenated amorphous silicon solar cells

    NASA Technical Reports Server (NTRS)

    Payson, J. S.; Abdulaziz, S.; Li, Y.; Woodyard, J. R.

    1991-01-01

    It was shown that 1 MeV proton irradiation with fluences of 1.25E14 and 1.25E15/sq cm reduces the normalized I(sub SC) of a-Si:H solar cell. Solar cells recently fabricated showed superior radiation tolerance compared with cells fabricated four years ago; the improvement is probably due to the fact that the new cells are thinner and fabricated from improved materials. Room temperature annealing was observed for the first time in both new and old cells. New cells anneal at a faster rate than old cells for the same fluence. From the annealing work it is apparent that there are at least two types of defects and/or annealing mechanisms. One cell had improved I-V characteristics following irradiation as compared to the virgin cell. The work shows that the photothermal deflection spectroscopy (PDS) and annealing measurements may be used to predict the qualitative behavior of a-Si:H solar cells. It was anticipated that the modeling work will quantitatively link thin film measurements with solar cell properties. Quantitative predictions of the operation of a-Si:H solar cells in a space environment will require a knowledge of the defect creation mechanisms, defect structures, role of defects on degradation, and defect passivation and annealing mechanisms. The engineering data and knowledge base for justifying space flight testing of a-Si:H alloy based solar cells is being developed.

  20. Proton emission from resonant laser absorption and self-focusing effects from hydrogenated structures

    NASA Astrophysics Data System (ADS)

    Cutroneo, M.; Torrisi, L.; Margarone, D.; Picciotto, A.

    2013-05-01

    Effects of resonant absorption and self-focusing are investigated by using fast and intense laser pulses. The ion emission and acceleration in the non-equilibrium laser-generated plasma are investigated at low and high intensities, from 1010 up to about 1016 W/cm2. The properties of plasma are strongly dependent on the time and space, laser intensity and wavelength. A special interest concerns the energetic and intense proton generation for the multiplicity use that proton beams have in different scientific fields (Nuclear Physics, Astrophysics, Bio-Medicine, Microelecronics, etc.). Investigations have been performed at INFN-LNS of Catania and at PALS Laboratory of Prague, by using thick and thin targets and different technique of ion analysis. The mechanisms of resonant absorption of the laser light, produced in special targets containing nanostructures with dimensions comparable with the laser wavelength, enhances the proton energy. The mechanisms of self-focusing, obtained by changing the laser focal distance from the target surface, increase the local intensity and consequently the high directional ion acceleration. Real-time ion detections were performed through Thomson parabola spectrometer (TPS), ion collectors (IC), SiC detectors and ion energy analyzer (IEA) employed in time-of-flight configuration (TOF). The energy and the amount of ions increase significantly when the two non-linear phenomena occurs, as will be described.

  1. Performance characteristics of single effect lithium bromide/ water absorption chiller for small data centers

    NASA Astrophysics Data System (ADS)

    Mysore, Abhishek Arun Babu

    A medium data center consists of servers performing operations such as file sharing, collaboration and email. There are a large number of small and medium data centers across the world which consume more energy and are less efficient when compared to large data center facilities of companies such as GOOGLE, APPLE and FACEBOOK. Such companies are making their data center facilities more environmental friendly by employing renewable energy solutions such as wind and solar to power the data center or in data center cooling. This not only reduces the carbon footprint significantly but also decreases the costs incurred over a period of time. Cooling of data center play a vital role in proper functioning of the servers. It is found that cooling consumes about 50% of the total power consumed by the data center. Traditional method of cooling includes the use of mechanical compression chillers which consume lot of power and is not desirable. In order to eliminate the use of mechanical compressor chillers renewable energy resources such as solar and wind should be employed. One such technology is solar thermal cooling by means of absorption chiller which is powered by solar energy. The absorption chiller unit can be coupled with either flat plate or evacuated tube collectors in order to achieve the required inlet temperature for the generator of the absorption chiller unit. In this study a modular data center is considered having a cooling load requirement of 23kw. The performance characteristics of a single stage Lithium Bromide/ water refrigeration is presented in this study considering the cooling load of 23kw. Performance characteristics of each of the 4 heat exchangers within the unit is discussed which helps in customizing the unit according to the users' specific needs. This analysis helps in studying the importance of different properties such as the effect of inlet temperatures of hot water for generator, inlet temperatures of cooling water for absorber and

  2. Flow pattern and mass transfer characteristics of valve tray in absorption process

    NASA Astrophysics Data System (ADS)

    Nurkhamidah, Siti; Altway, Ali; Wulansari, Ayu Savitri; Khanifah, Evi Fitriyah

    2015-12-01

    The flow pattern characteristics of valve tray in absorption process which is expressed in pressure drop and the number of equivalent tank in series (N) has an important role to know the efficiency and performance of a process. This study has been done in the absorption column by using water and air as liquid and gas phase, respectively. To observe pressure drop and flow pattern in the column, flow rate of liquid and air has been variated. Flow pattern has been determined by using pulse method and using NaCl as tracer. The experiment results show that the column pressure drop is mainly influenced by the liquid height on the tray. When the water flow rate is high, liquid height on the tray is higher so that the column pressure drops increases. Flow pattern characteristic of fluid on valve tray is affected by water and air flowrates. For high water flow rate, the residence time distribution (RTD) curve is sharper and the number of N is greater and the flow pattern tends to a plug flow. However, the number of N decreases when the air flowrate increases. The liquid-side mass transfer coefficient (kLa') is shown by the following empirical relationship kLa' = 2,607QL0,202Qv0,456.

  3. Cold Atomic Hydrogen, Narrow Self-Absorption, and the Age of Molecular Clouds

    NASA Technical Reports Server (NTRS)

    Goldsmith, Paul F.

    2006-01-01

    This viewgraph presentation reviews the history, and current work on HI and its importance in star formation. Through many observations of HI Narrow Self Absorption (HINSA) the conclusions are drawn and presented. Local molecular clouds have HI well-mixed with molecular constituents This HI is cold, quiescent, and must be well-shielded from the UV radiation field The density and fractional abundance (wrt H2) of the cold HI are close to steady state values The time required to convert these starless clouds from purely HI initial state to observed present composition is a few to ten million years This timescale is a lower limit - if dense clouds being swept up from lower density regions by shocks, the time to accumulate material to get A(sub v) is approximately 1 and provide required shielding may be comparable or longer

  4. Cold Atomic Hydrogen, Narrow Self-Absorption, and the Age of Molecular Clouds

    NASA Technical Reports Server (NTRS)

    Goldsmith, Paul F.

    2006-01-01

    This viewgraph presentation reviews the history, and current work on HI and its importance in star formation. Through many observations of HI Narrow Self Absorption (HINSA) the conclusions are drawn and presented. Local molecular clouds have HI well-mixed with molecular constituents This HI is cold, quiescent, and must be well-shielded from the UV radiation field The density and fractional abundance (wrt H2) of the cold HI are close to steady state values The time required to convert these starless clouds from purely HI initial state to observed present composition is a few to ten million years This timescale is a lower limit - if dense clouds being swept up from lower density regions by shocks, the time to accumulate material to get A(sub v) is approximately 1 and provide required shielding may be comparable or longer

  5. Experimental study on evaporation characteristics of a hydrogen peroxide droplet at elevated temperature

    NASA Astrophysics Data System (ADS)

    Won, Jonghan; Kang, Hongjae; Baek, SeungWook; Kwon, Sejin

    2017-05-01

    In this study, evaporation characteristics of a hydrogen peroxide droplet, 90% purity, was experimentally investigated at elevated temperature (between 400 and 800 °C) and atmospheric pressure under normal gravity. Elevated temperature atmosphere was provided by electric furnace inside the chamber. The range of a droplet size was 1.1 mm to 1.3 mm. The evaporation process of a droplet was recorded by high speed CCD camera. As analysing the image extracted from the camera using the program, evaporation rate of a single droplet was calculated at each ambient temperature. After thermal expansion period, evaporation rate of a hydrogen peroxide droplet followed d2-law but thermal expansion period didn't clearly separate at 400 °C. The evaporation rate increased with increase in ambient temperature. Also thermal decomposition of hydrogen peroxide increased at high temperature.

  6. Effect of hydrogen bonding on the infrared absorption intensity of OH stretch vibrations

    NASA Astrophysics Data System (ADS)

    Athokpam, Bijyalaxmi; Ramesh, Sai G.; McKenzie, Ross H.

    2017-05-01

    We consider how the infrared intensity of a hydrogen-bonded OH stretch varies from weak to strong H-bonds using a theoretical model. We obtain trends for the fundamental and overtone transition intensities as a function of the donor-acceptor distance, a common measure of H-bond strength. Building upon our earlier work using a two-diabatic state model, we introduce a Mecke function-based dipole moment for the H-bond and calculate transition moments using one-dimensional vibrational eigenstates along the H-atom transfer coordinate. The fundamental intensity is found to be over 20-fold enhanced for strong H-bonds, where non-Condon effects are significant. We analyse isotope effects, including the secondary geometric isotope effect. The first overtone intensity varies non-monotonically with H-bond strength; suppression occurs for weak bonds but strong enhancements are possible for strong H-bonds. We also study how these trends are affected by Mecke parameter variations. For a few specific dimers, we compare our results with earlier works.

  7. Metal-and hydrogen-bonding competition during water absorption on Pd(111) and Ru(0001)

    SciTech Connect

    Tatarkhanov, Mouslim; Ogletree, D. Frank; Rose, Franck; Mitsui, Toshiyuki; Fomin, Evgeny; Rose, Mark; Cerda, Jorge I.; Salmeron, Miquel

    2009-09-03

    The initial stages of water adsorption on the Pd(111) and Ru(0001) surfaces have been investigated experimentally by Scanning Tunneling Microscopy in the temperature range between 40 K and 130 K, and theoretically with Density Functional Theory (DFT) total energy calculations and STM image simulations. Below 125 K water dissociation does not occur at any appreciable rate and only molecular films are formed. Film growth starts by the formation of flat hexamer clusters where the molecules bind to the metal substrate through the O-lone pair while making H-bonds with neighboring molecules. As coverage increases, larger networks of linked hexagons are formed with a honeycomb structure, which requires a fraction of the water molecules to have their molecular plane perpendicular to the metal surface with reduced water-metal interaction. Energy minimization favors the growth of networks with limited width. As additional water molecules adsorb on the surface they attach to the periphery of existing islands, where they interact only weakly with the metal substrate. These molecules hop along the periphery of the clusters at intermediate temperatures. At higher temperatures they bind to the metal to continue the honeycomb growth. The water-Ru interaction is significantly stronger than the water-Pd interaction, which is consistent with the greater degree of hydrogen-bonded network formation and reduced water-metal bonding observed on Pd relative to Ru.

  8. Deuterium absorption and material phase characteristics of SAES St 198 Zr-Fe Alloy. Revision 1

    SciTech Connect

    Nobile, A.; Mosley, W.C.; Holder, J.S.; Brooks, K.N.

    1994-01-01

    This document reports deuterium absorption and material phase characteristics of SAES St 198 Zr-Fe Alloy (76.5% Zr). Scanning electron microscope images of polished surfaces, electron probe microanalysis, and x-ray powder diffractometry indicated the presence of a primary Zr{sub 2}Fe phase with secondary phases of ZrFe{sub 2}, Zr{sub 5}FeSn, {alpha}-Zr, and Zr{sub 6}Fe{sub 3}O. A statistically designed experiment to determine the effects of temperature, time, and vacuum quality on activation of St 198 revealed that, when activated at low temperature (350C), deuterium absorption rate was slower when the vacuum quality was poor (2.5 Pa vs. 3 {times} 10{sup {minus}4} Pa). However, at higher activation temperature (500C), deuterium absorption rate was fast and was independent of vacuum quality. Deuterium pressure-composition-temperature (P-C-T) data are reported for St 198 in the temperature range 200 to 500C. The P-C-T data over the full range of deuterium loading and at temperatures of 350C and below is described an expression. At higher temperatures, one or more secondary reactions in the solid phase occur that slowly consume D{sub 2} from the gas phase. X-ray diffraction and other data suggest these reactions to be: 2 Zr{sub 2}FeD{sub x} {yields} xZrD{sub 2} + x/3 ZrFe{sub 2} + (2 {minus} 2/3x) Zr{sub 2}Fe and Zr{sub 2}FeD{sub x} + (2 {minus} 1/2x) D{sub 2} {yields} 2 ZrD{sub 2} + Fe, where 0 < x < 3. Reaction between gas-phase deuterium and Zr{sub 2}Fe formed in the first reaction accounts for the observed consumption of deuterium from the gas phase by this reaction.

  9. Fluorescence and absorption characteristics of p-xylene: applicability for temperature measurements

    NASA Astrophysics Data System (ADS)

    Wang, Qianlong; Zhang, Yuyin; Jiang, Liqiao; Zhao, Daiqing; Guibert, Philippe; Yang, Shunhua

    2017-09-01

    This paper explores the characteristics of absorption and fluorescence spectra of p-xylene within the temperature range that is frequently encountered during the mixture formation in internal combustion engines. At 266 nm wavelength, the p-xylene absorption cross section shows a mean value of (3.4 ± 0.2) × 10-19 cm2/molecule within the temperature range from 423 to 623 K in N2. As expected, fluorescence peak intensity decreases by a factor of 3 when the temperature increases by 100 K, due to a increasing non-radiative decay rate of excited state at increasing temperatures. In addition, the suitability of p-xylene for temperature measurements in the gas phase via the single-wavelength excitation (at 266 nm) two-color detection laser-induced fluorescence imaging is explored. Combinations of spectral detection bands were compared and the combination of 320/289 nm provides the best temperature performance with a relative error of 2.6% within the investigated temperature range. It is also shown that the temperature field measurement has not been strongly affected by the laser attenuation.

  10. A simple fiber optic humidity sensor based on water-absorption characteristic of CAB

    NASA Astrophysics Data System (ADS)

    Li, Guang; Xu, Wei; Huang, Xuguang

    2015-02-01

    A simple fiber-optic relative humidity sensor based on cellulose acetate butyrate (CAB) and Fresnel reflection is proposed and investigated theoretically and experimentally. The sensing system is only composed of one light source, three optical couplers, two photo-detectors and two fiber sensing ends. The operation principle is based on relative Fresnel reflection and water-absorption characteristic of the CAB which simultaneously contains hydrophilic and hydrophobic groups. The water absorption process will lead to variation of the CAB's refractive index or permittivity. It has to be noted that the double-channel system can effectively eliminate the intensity fluctuation of the light source and the influence of the environment. In this paper, the relative humidity environments approximately ranging from 10 % to 100% are generated and measured both in the humidification and dehumidification processes, which shows a good repeatability and reveals a very good fitting feature with a high value of R2 above 0.99. It is of reflection type and can be simply extend to be a multi-point-monitoring system. The sensing system is of cost- effective, simple operation and high precision.

  11. Estimating organic micro-pollutant removal potential of activated carbons using UV absorption and carbon characteristics.

    PubMed

    Zietzschmann, Frederik; Altmann, Johannes; Ruhl, Aki Sebastian; Dünnbier, Uwe; Dommisch, Ingvild; Sperlich, Alexander; Meinel, Felix; Jekel, Martin

    2014-06-01

    Eight commercially available powdered activated carbons (PAC) were examined regarding organic micro-pollutant (OMP) removal efficiencies in wastewater treatment plant (WWTP) effluent. PAC characteristic numbers such as B.E.T. surface, iodine number and nitrobenzene number were checked for their potential to predict the OMP removal of the PAC products. Furthermore, the PAC-induced removal of UV254 nm absorption (UVA254) in WWTP effluent was determined and also correlated with OMP removal. None of the PAC characteristic numbers can satisfactorily describe OMP removal and accordingly, these characteristics have little informative value on the reduction of OMP concentrations in WWTP effluent. In contrast, UVA254 removal and OMP removal correlate well for carbamazepine, diclofenac, and several iodinated x-ray contrast media. Also, UVA254 removal can roughly describe the average OMP removal of all measured OMP, and can accordingly predict PAC performance in OMP removal. We therefore suggest UVA254 as a handy indicator for the approximation of OMP removal in practical applications where direct OMP concentration quantification is not always available. In continuous operation of large-scale plants, this approach allows for the efficient adjustment of PAC dosing to UVA254, in order to ensure reliable OMP removal whilst minimizing PAC consumption.

  12. Effects of nitrogen doping on the electrical conductivity and optical absorption of ultrananocrystalline diamond/hydrogenated amorphous carbon films prepared by coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Zkria, Abdelrahman; Katamune, Yūki; Yoshitake, Tsuyoshi

    2016-07-01

    3 at. % nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were synthesized by coaxial arc plasma deposition. Optically, the films possess large absorption coefficients of more than 105 cm-1 at photon energies from 3 to 5 eV. The optical band gap was estimated to be 1.28 eV. This value is smaller than that of undoped films, which might be attributable to increased sp2 fractions. The temperature dependence of the electrical conductivity implies that carrier transport follows a hopping conduction model. Heterojunctions with p-type Si substrates exhibited a typical rectifying action. From the capacitance-voltage characteristics that evidently indicated the expansion of a depletion region into the film side, the built-in potential and carrier concentration were estimated to be 0.51 eV and 7.5 × 1016 cm-3, respectively. It was experimentally demonstrated that nitrogen-doped UNCD/a-C:H films are applicable as an n-type semiconductor.

  13. Study of crash energy absorption characteristics of inversion tube on passenger vehicle

    NASA Astrophysics Data System (ADS)

    Liu, Jiandong; Liu, Tao; Yao, Shengjie; Zhao, Rutao

    2017-09-01

    This article studied the energy absorption characteristics of the inversion tube and acquired the inversion tube design key dimensions under theoretical conditions by performing formula derivation in the quasi-static and dynamic state based on the working principle of the inversion tube: free inversion. The article further adopted HyperMesh and LS-Dyna to perform simulation and compared the simulation result with the theoretical calculating value for comparison. The design was applied in the full-vehicle model to perform 50km/h front fullwidth crash simulation. The findings showed that the deformation mode of the inversion tube in the full-vehicle crash was consistent with the design mode, and the inversion tube absorbed 33.0% of total energy, thereby conforming to the vehicle safety design requirements.

  14. Molecular dynamics models and thermodynamic characteristics of hydrogen bonds in 1,2-ethanediol

    NASA Astrophysics Data System (ADS)

    Usacheva, T. M.; Zhuravlev, V. I.; Lifanova, N. V.; Matveev, V. K.

    2017-06-01

    A correlation between the lifetimes of hydrogen bonds and the thermodynamic characteristics of their formation and breaking, and the experimental relaxation times of dielectric spectra and the energy characteristics of relaxation processes, is observed via molecular dynamics (MD) simulation of the rearranging of the network structure of 1,2-ethanediol. The MD torsional frequency of the transition of gauche conformer tGg' at 224.1 cm-1 and the experimental frequency of the band maximum of torsional vibrations at 230 cm-1 in the infrared spectrum correlate with the oscillation frequency of molecules at 240 cm-1 inside clusters in the Dissado-Hill (DH) model. The MD and DH models indicate a predominantly parallel alignment of the electric dipole moments of conformers tGg' in the three-dimensional network of hydrogen bonds of the liquid 1,2-ethanediol phase.

  15. Superconducting characteristics of short MgB2 wires of long level sensor for liquid hydrogen

    NASA Astrophysics Data System (ADS)

    Takeda, M.; Inoue, Y.; Maekawa, K.; Matsuno, Y.; Fujikawa, S.; Kumakura, H.

    2015-12-01

    To establish the worldwide storage and marine transport of hydrogen, it is important to develop a high-precision and long level sensor, such as a superconducting magnesium diboride (MgB2) level sensor for large liquid hydrogen (LH2) tanks on board ships. Three 1.7- m-long MgB2 wires were fabricated by an in situ method, and the superconducting characteristics of twenty-four 20-mm-long MgB2 wires on the 1.7-m-long wires were studied. In addition, the static level-detecting characteristics of five 500-mm-long MgB2 level sensors were evaluated under atmospheric pressure.

  16. LABORATORY MEASUREMENTS OF INFRARED ABSORPTION SPECTRA OF HYDROGEN-ORDERED ICE: A STEP TO THE EXPLORATION OF ICE XI IN SPACE

    SciTech Connect

    Arakawa, M.; Kagi, H.; Fukazawa, H. E-mail: kagi@eqchem.s.u-tokyo.ac.jp

    2009-10-01

    Infrared absorption spectra of ice were obtained at 4, 60, 100, 140, 160, and 240 K to make spectroscopic observations of hydrogen ordering at low temperatures. A broad peak observed at around 850 cm{sup -1} (11.7 {mu}m) was derived from libration of water molecules. The peak width was notably narrower at temperatures less than 140 K. A decrease in the peak width occurring in accordance with the formation of ice with ordered arrangements of hydrogen atoms was suggested from incoherent inelastic neutron-scattering studies. These results are consistent with ordering of hydrogen atoms. The existence of hydrogen-ordered ice in space is the subject of continuing astronomical debate. Our results demonstrate that ordered ice in space is detectable using infrared telescopes and planetary exploration.

  17. Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

    NASA Astrophysics Data System (ADS)

    Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

    2017-03-01

    Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

  18. Aging Effects on the Hydrogen Storage Characteristics of Li-Mg-B-N-H Complex Hydrides

    NASA Astrophysics Data System (ADS)

    Srinivasan, Sesha; Vickers, Eric; Mulharan, James; Darkazalli, Gazi; Goswami, Yogi; Stefanakos, Elias; FLPoly-CERC Collaboration

    2015-03-01

    The aging effects on the hydrogen storage characteristics and chemical formulations of the complex hydrides are discussed in this study. The aging effects due to atmospheric events such as oxygen and moisture coverage and self-decomposition are currently under investigation. The candidate material chosen for this study is Lithium/Magnesium based complex hydride LiBH4/LiNH2/MgH2. These materials were prepared using high energy ball milling under Ar/H2 atmosphere with different milling durations. The chemical, structural and microstructural characteristics of the synthesized and aged materials were compared and investigated using TGA/DSC, FTIR, XRD, BET and SEM analytical tools. Hydrogen storage properties such as hydrogen sorption kinetics, cycle life and pressure-composition isotherm (PCI) was examined via high pressure, high temperature Sievert's type apparatus. This current study will shed light to compare and contrast the above mentioned characteristics for the aged samples practically at the same experimental conditions. Furthermore, we have investigated the relationship between the aging effects with respect to the crystallite sizes of the candidate compounds and their nano-dopant variants. We acknowledge the grant from Florida Energy Systems Consortium and support from Florida Polytechnic University.

  19. Atomic-level Pd-Pt alloying and largely enhanced hydrogen-storage capacity in bimetallic nanoparticles reconstructed from core/shell structure by a process of hydrogen absorption/desorption.

    PubMed

    Kobayashi, Hirokazu; Yamauchi, Miho; Kitagawa, Hiroshi; Kubota, Yoshiki; Kato, Kenichi; Takata, Masaki

    2010-04-28

    We have achieved the creation of a solid-solution alloy where Pd and Pt are homogeneously mixed at the atomic level, by a process of hydrogen absorption/desorption as a trigger for core (Pd)/shell (Pt) nanoparticles. The structural change from core/shell to solid solution has been confirmed by in situ powder X-ray diffraction, energy dispersive spectra, solid-state (2)H NMR measurement, and hydrogen pressure-composition isotherms. The successfully obtained Pd-Pt solid-solution nanoparticles with a Pt content of 8-21 atom % had a higher hydrogen-storage capacity than Pd nanoparticles. Moreover, the hydrogen-storage capacity of Pd-Pt solid-solution nanoparticles can be tuned by changing the composition of Pd and Pt.

  20. Nanosecond pulsed humid Ar plasma jet in air: shielding, discharge characteristics and atomic hydrogen production

    NASA Astrophysics Data System (ADS)

    Yatom, Shurik; Luo, Yuchen; Xiong, Qing; Bruggeman, Peter J.

    2017-10-01

    Gas phase non-equilibrium plasmas jets containing water vapor are of growing interest for many applications. In this manuscript, we report a detailed study of an atmospheric pressure nanosecond pulsed Ar  +  0.26% H2O plasma jet. The plasma jet operates in an atmospheric pressure air surrounding but is shielded with a coaxial argon flow to limit the air diffusion into the jet effluent core. The jet impinges on a metal plate electrode and produces a stable plasma filament (transient spark) between the needle electrode in the jet and the metal plate. The stable plasma filament is characterized by spatially and time resolved electrical and optical diagnostics. This includes Rayleigh scattering, Stark broadening of the hydrogen Balmer lines and two-photon absorption laser induced fluorescence (TaLIF) to obtain the gas temperature, the electron density and the atomic hydrogen density respectively. Electron densities and atomic hydrogen densities up to 5 × 1022 m-3 and 2 × 1022 m-3 have been measured. This shows that atomic hydrogen is one of the main species in high density Ar-H2O plasmas. The gas temperature does not exceed 550 K in the core of the plasma. To enable in situ calibration of the H TaLIF at atmospheric pressure a previously published O density calibration scheme is extended to include a correction for the line profiles by including overlap integrals as required by H TaLIF. The line width of H TaLIF, due to collision broadening has the same trend as the neutral density obtained by Rayleigh scattering. This suggests the possibility to use this technique to in situ probe neutral gas densities.

  1. Relationship between element-selective electronic states and hydrogen absorption properties of Pd-M (M =Ru ,Rh,Ag, and Au) alloys

    NASA Astrophysics Data System (ADS)

    Fujii, Kanako; Ishimatsu, Naoki; Maruyama, Hiroshi; Shishidou, Tatsuya; Hayakawa, Shinjiro; Kawamura, Naomi

    2017-01-01

    To understand how the constituent atoms participate in the hydrogenation of Pd-based alloys at ˜0.1 MPa of hydrogen pressure (PH2),we investigated the electronic states in Pd-M (M =Ru,Rh,Ag, and Au) alloys and their hydrides element-selectively by using x-ray absorption spectroscopy at the L2 ,3 edges. Spectral changes near the absorption edge demonstrate that both Pd and M atoms form bonds with H atoms in the Pd-M (M =Ru and Rh) alloys even at PH 2˜0.1 MPa. This is a striking result because high pressures of more than 1 GPa are required for the hydrogenation of Rh and Ru pure metals. In contrast, only Pd atoms bond with H atoms and the M -H bond is absent in the case of Pd-M (M =Ag and Au) alloys. Therefore, the hydrogen-induced changes in the electronic states differ between M s with fully occupied d shells and M s with partially occupied d shells. This study reveals that the thermodynamic hydrogenation properties of Pd-M alloys can be determined by a combination of the formation of the M -H bond and lattice expansion or compression by alloying Pd metal with M .

  2. Emergence of charge-transfer-to-solvent band in the absorption spectra of hydrogen halides on ice nanoparticles: spectroscopic evidence for acidic dissociation.

    PubMed

    Oncák, Milan; Slavícek, Petr; Poterya, Viktoriya; Fárník, Michal; Buck, Udo

    2008-06-19

    Extensive ab initio calculations complemented by a photodissociation experiment at 193 nm elucidate the nature of hydrogen halide molecules bound on free ice nanoparticles. Electronic absorption spectra of small water clusters (up to 5 water molecules) and water clusters doped with hydrogen fluoride, hydrogen chloride and hydrogen bromide were calculated. The spectra were modeled at the time-dependent density functional (TDDFT) level of theory with the BHandHLYP functional using the reflection principle. We observe the emergence of a charge-transfer-to-solvent (CTTS) band in the absorption spectra upon the acidic dissociation of the hydrogen halides. The CTTS band provides a spectroscopically observable feature for the acidic dissociation. The calculated spectra were compared with our new experimental photodissociation data for larger water clusters doped with HCl and HBr. We conclude that HCl and HBr dissociate to a large extent on the surface of ice nanoparticles at temperatures near 120 K and photoactive products are formed. The acidic dissociation of HX leads to an enhancement by about 4 orders of magnitude of the HCl photolysis rate in the 200-300 nm region, which is potentially relevant for the halogen budget in the atmosphere.

  3. Near-infrared (NIR) study of hydrogen bonding of methanol molecules in polar and nonpolar solvents: an approach from concentration-dependent molar absorptivity.

    PubMed

    Mikami, Yuho; Ikehata, Akifumi; Hashimoto, Chihiro; Ozaki, Yukihiro

    2014-01-01

    Differences in the hydrogen-bonding states of methanol in polar and nonpolar solvents were studied by using the first overtone of O-H stretching vibrations observed in the near-infrared (NIR) band ranging from 7500 to 6000 cm(-1). To eliminate the absorption of solvents, NIR-inactive nonpolar solvents carbon tetrachloride (CCl4) and tetrachloroethylene (C2Cl4) were chosen, along with deuterium-substituted polar solvents acetone-d6, acetonitrile-d3, 1,4-dioxane-d8, and tetrahydrofuran (THF)-d8. The changes in the hydrogen-bonding states of methanol during mixing with the solvents were estimated using the extended molar absorption spectrum, which was defined as the concentration difference. The extended molar absorption spectra in different concentrations were decomposed into a finite number of independent factors using a multivariate curve resolution-alternating least squares calculation. Two and three such factors were sufficient to reproduce the extended molar absorption spectra for the nonpolar and polar solvents, respectively. The detailed assignments of each factor were estimated using the calculated loadings and scores. A similarity analysis was also applied to the extended molar absorption spectra of methanol and effectively quantified the deviation from the spectrum of pure methanol. The methanol and solvent affinities were also compared.

  4. Reversible Hydrogen Storage Characteristics of Catalytically Enhanced Ca(Li)-nMg-B-N-H System

    NASA Astrophysics Data System (ADS)

    Srinivasan, Sesha; Emre Demircak, Dervis; Sharma, Prakash; Yogi, Goswami; Stefanakos, Elias

    2013-04-01

    The aim of the present investigation is to study the synergistic effects of multi-walled carbon nanotubes, Nb2O5 and other catalysts for reversible hydrogen storage characteristics of Ca(Li)-nMg-B-N-H systems. Multinary hydride using light weight, high capacity hydride compounds such as Ca(BH4)2, LiBH4, LiNH2, nanoMgH2 in 3:1:8:4 composition was synthesized using high energy planetary milling under Ar/H2 ambient. Various nano additives and bi-metallic catalysts were added in a very small concentration with the host hydride (Ca)Li-nMg-B-N-H. The TGA and DSC results demonstrated that the catalytically enhanced Ca(Li)-nMg-B-N-H with hydrogen release at lower temperatures when compared to the pristine systems such as either Ca-Li-B-H or Ca-Li-Mg-B-H. Analyses of metrological characterization using XRD, SEM and have revealed the effectiveness and the role of the catalytic nanoparticles and their enhanced reversible hydrogen storage behavior on the host hydride matrix. The mass spectrometric investigations employing RGA on these nanocrystalline, multi-component hydride systems exhibit the release of hydrogen in major proportion (˜80-90%) as compared to previously attributed ammonia.

  5. HST/COS SPECTRA OF DF Tau AND V4046 Sgr: FIRST DETECTION OF MOLECULAR HYDROGEN ABSORPTION AGAINST THE Ly{alpha} EMISSION LINE

    SciTech Connect

    Yang Hao; Linsky, Jeffrey L.; France, Kevin E-mail: jlinsky@jilau1.colorado.edu

    2011-03-20

    We report the first detection of molecular hydrogen (H{sub 2}) absorption in the Ly{alpha} emission line profiles of two classical T Tauri stars (CTTSs), DF Tau and V4046 Sgr, observed by the Hubble Space Telescope/Cosmic Origins Spectrograph. This absorption is the energy source for many of the Lyman-band H{sub 2} fluorescent lines commonly seen in the far-ultraviolet spectra of CTTSs. We find that the absorbed energy in the H{sub 2} pumping transitions from a portion of the Ly{alpha} line significantly differ from the amount of energy in the resulting fluorescent emission. By assuming additional absorption in the H I Ly{alpha} profile along our light of sight, we can correct the H{sub 2} absorption/emission ratios so that they are close to unity. The required H I absorption for DF Tau is at a velocity close to the radial velocity of the star, consistent with H I absorption in the edge-on disk and interstellar medium. For V4046 Sgr, a nearly face-on system, the required absorption is between +100 km s{sup -1} and +290 km s{sup -1}, most likely resulting from H I gas in the accretion columns falling onto the star.

  6. An Investigation into the Effect of Stabiliser Content on the Minimum Characteristic Chamber Length for Homogeneously-Catalysed Hydrogen Peroxide

    DTIC Science & Technology

    2007-11-02

    packs to achieve a heterogeneous catalytic reaction to decompose the propellant into steam and oxygen. The decomposition of highly stabilised ...England, Private Communication. May 2004. [3] Musker, A. J. "Highly Stabilised Hydrogen Peroxide as a Rocket Propellant ", Proceedings of the...Investigation into the Effect of Stabiliser Content on the Minimum Characteristic Chamber Length for Homogeneously-Catalysed Hydrogen Peroxide 5c

  7. Heat and mass transfer characteristics of absorption of R134a into DMAC in a horizontal tube absorber

    NASA Astrophysics Data System (ADS)

    Harikrishnan, L.; Maiya, M. P.; Tiwari, S.; Wohlfeil, A.; Ziegler, F.

    2009-10-01

    In this paper the heat and mass transfer characteristics of a horizontal tube absorber for the mixture R134a/DMAC in terms of experimentally gained heat and mass transfer coefficients are presented. The heat transfer coefficient is mainly dependent on the solution’s mass flow rate. The mass transfer coefficient is strongly related to the subcooling of the solution. The data are compared to experimental absorption characteristics of water into aqueous lithium bromide in an absorption chiller. The mass transfer coefficients are of similar size whereas the heat transfer coefficients are about one order of magnitude smaller for R134a-DMAC.

  8. Monitoring of Atmospheric Hydrogen Peroxide in Houston Using Long Path-Length Laser-Based Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sanchez, N. P.; Cao, Y.; Jiang, W.; Tittel, F. K.; Griffin, R. J.

    2014-12-01

    Hydrogen peroxide (H2O2) is a relevant atmospheric species mainly formed by recombination of hydroperoxyl radicals. H2O2 participates in the formation of sulfate aerosol by in-cloud oxidation of S(IV) to S(VI) and has been associated with the generation of multi-functional water soluble organic compounds in atmospheric particulate matter. Furthermore, H2O2 plays an important role in the oxidative capacity of the atmosphere as it acts as a reservoir for HOx radicals (OH and HO2). Particular conditions in the Houston area (e.g. extensive presence of petrochemical industry and high ozone and humidity levels) indicate the potential relevance of this species at this location. Despite its atmospheric relevance, no reports on the levels of H2O2 in Houston have been presented previously in the scientific literature. Determination of atmospheric H2O2 usually has been conducted based on transfer of the gas-phase H2O2 to the liquid phase prior to quantification by techniques such as fluorescence spectroscopy. Although these methods allow detection of H2O2 at the sub-ppb level, they present some limitations including the interference from other atmospheric constituents and potential sampling artifacts. In this study, a high sensitivity sensor based on long-path absorption spectroscopy using a distributed-feedback quantum cascade laser was developed and used to conduct direct gas-phase H2O2 monitoring in Houston. The sensor, which targets a strong H2O2 absorption line (~7.73 μm) with no interference from other atmospheric species, was deployed at a ground level monitoring station near the University of Houston main campus during summer 2014. The performance of this novel sensor was evaluated by side-by-side comparison with a fluorescence-based instrument typically used for atmospheric monitoring of H2O2. H2O2 levels were determined, and time series of H2O2 mixing ratios were generated allowing insight into the dynamics, trends, and atmospheric inter-relations of H2O2 in the

  9. Hydrogen

    PubMed Central

    Bockris, John O’M.

    2011-01-01

    The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech. PMID:28824125

  10. Hydrogen systems

    SciTech Connect

    Veziroglu, T.N.; Zhu, Y.; Bao, D.

    1985-01-01

    This book presents the papers given at a symposium on hydrogen fuels. Topics considered at the symposium included hydrogen from fossil fuels, electrolysis, photolytic hydrogen generation, thermochemical and photochemical methods of hydrogen production, catalysts, hydrogen biosynthesis, novel and hybrid methods of hydrogen production, storage and handling, metal hydrides and their characteristics, utilization, hydrogen fueled internal combustion engines, hydrogen gas turbines, hydrogen flow and heat transfer, fuel cells, synthetic hydrocarbon fuels, thermal energy transfer, hydrogen purification, research programs, economics, primary energy sources, environmental impacts, and safety.

  11. [Research on serum prostate-specific antigen measurement by characteristic spectral absorption method].

    PubMed

    Zhu, Jian-ming; Chen, Zhen-cheng

    2012-01-01

    A serum prostate-specific antigen (PSA) measurement method was studied using immunochromatography-based colloidal gold-marked test-strips and characteristic spectral absorption method. Some LEDs in the range from 520 to 535 nm irradiated the test-strips sampled by PSA, and then a photodiode in the range from 520 to 540 nm measured the reflex light at the specific area. Accordingly, the absorbency of the strip could be calculated, then the relationship between PSA level and strip absorbency could be ascertained by linear fit method. The experimental measurement system was calibrated by different PSA standard solutions in this research. As a result, in the range between 5 to 50 ng x mL(-1), the levels of PSA have a linear relationship with the absorbency of test-strips. Some experiments were completed by 21 different PSA standard solutions within that range, and then the correlation coefficient of the results is equal to 0.910, which proves that the proposed method for serum PSA level measurement is feasible.

  12. Solvent based hydrogen bonding: impact on poly(3-hexylthiophene) nanoscale morphology and charge transport characteristics.

    PubMed

    Chang, Mincheol; Choi, Dalsu; Fu, Boyi; Reichmanis, Elsa

    2013-06-25

    We demonstrate that supramolecular assembly and subsequent enhancement of charge transport characteristics of conjugated polymers can be facilitated simply by adding small amounts of a more volatile poor solvent, which can hydrogen bond with the majority solvent. Addition of up to 2 vol % acetone to a precursor solution of poly(3-hexylthiophene) (P3HT) in chloroform leads to approximately a 4-fold increase in P3HT field-effect mobility. The improvement is associated with hydrogen bonding interactions between acetone and chloroform which decrease the evaporation rate of the mixed solvent. P3HT is less soluble in the binary solvent than in the more readily vaporized chloroform component, and this characteristic enables the supramolecular assembly of P3HT chains at the nanoscale. Two-dimensional molecular ordering of the polymer film was controlled by varying the quantity of poor solvent added to the precursor solution, and the correlation between field-effect mobility and molecular ordering was investigated. Hansen solubility parameters were used to systematically understand how the solvent mixture enhances the alignment and assembly of polymer chains and influences subsequent thin film properties. The value of the relative energy difference (RED) of the solvent with respect to P3HT increased from less than 1 to more than 1 during film formation, which indicates that the solvent characteristics are initially those of a good solvent but transform into those of a poor dissolution medium. A mechanistic illustration of the molecular ordering process during film formation is postulated.

  13. [The study of characteristics of absorption and separation of different glycoside on macropore resins].

    PubMed

    Bi, Yue-qi; Hou, Shi-xiang; Mao, Sheng-jun; Song, Ying-xin

    2003-03-01

    To study the absorption and separation of different glycoside on different macropore resins. Take baikal skullcap root, cape jasmine fruit and white peony root as samples and study the different characterstics of absorption and separation of these samples on macropore resins such as D101 and so on. The static absorption effect of the the three aglycones on six different macropore resins is baicalin > lactiflorin > gardoside. Their elution are 75% CH3OH, 25% CH3OH, and 45% CH3OH. Their elution rates are 60%, 93%, and 93%. Similar molecules may not have similar absorption abilities on same macropore resins, but the effect of absorption has something to do with the structures of the molecules, the more double-bonds the molecules have, the greater the absorption force the resins have.

  14. Pressure-driven variations of hydrogen bonding energy in ammonium azide (NH4N3): IR absorption and Raman scattering studies.

    PubMed

    Wu, Xiaoxin; Ma, Fengxian; Ma, Chunli; Cui, Hang; Liu, Zhenxian; Zhu, Hongyang; Wang, Xiaoli; Cui, Qiliang

    2014-07-14

    In this study, high pressure infrared (IR) absorption and Raman scattering studies for ammonium azide (NH4N3) were carried out at room temperature up to 20 GPa and 22 GPa, respectively. For comparison and further assignment, the vibrational spectra at ambient conditions were calculated using CASTEP code, particularly for the far- and mid-IR modes. The recorded vibrational data consistently indicated a pressure-induced phase transition at 2.9 GPa. All observed vibrational modes maintained their identities at the high pressure phase, indicating that NH4N3 was still presented in the form of ammonium cations and azide anions linked by the hydrogen bond (N-H⋯N). Above 2.9 GPa, the relative magnitude of the torsional mode weakened and the N-H symmetric stretch displayed a redshift, indicating strengthened hydrogen bonding energy. The opposite effects were observed above 12 GPa, where the relative magnitude of the torsional mode strengthened and the N-H symmetric stretch reverted to a blueshift, indicating weakened hydrogen bonding energy. It can be concluded that the hydrogen bonding energy exhibited a weakening (0-2.9 GPa), strengthening (2.9-12 GPa), and then again weakening (12-22 GPa) phenomena with the increasing of compression. The hydrogen bonding energy changing with the increase of pressure can be ascribed to a phase transition at 2.9 GPa and a rotational or bending behavior of azide ions at 12 GPa.

  15. Ethylene hydrogenation catalysis on Pt(111) single-crystal surfaces studied by using mass spectrometry and in situ infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Tillekaratne, Aashani; Simonovis, Juan Pablo; Zaera, Francisco

    2016-10-01

    The catalytic hydrogenation of ethylene promoted by a Pt(111) single crystal was studied by using a ultrahigh-vacuum surface-science instrument equipped with a so-called high-pressure cell. Kinetic data were acquired continuously during the catalytic conversion of atmospheric-pressure mixtures of ethylene and hydrogen by using mass spectrometry while simultaneously characterizing the surface species in operando mode by reflection-absorption infrared spectroscopy (RAIRS). Many observations reported in previous studies of this system were corroborated, including the presence of adsorbed alkylidyne intermediates during the reaction and the zero-order dependence of the rate of hydrogenation on the pressure of ethylene. In addition, the high quality of the kinetic data, which could be recorded continuously versus time and processed to calculate time-dependent turnover frequencies (TOFs), afforded a more detailed analysis of the mechanism. Specifically, deuterium labeling could be used to estimate the extent of isotope scrambling reached with mixed-isotope-substituted reactants (C2H4 + D2 and C2D4 + H2). Perhaps the most important new observation from this work is that, although extensive H-D exchange takes place on ethylene before being fully converted to ethane, the average stoichiometry of the final product retains the expected stoichiometry of the gas mixture, that is, four regular hydrogen atoms and two deuteriums per ethane molecule in the case of the experiments with C2H4 + D2. This means that no hydrogen atoms are removed from the surface via their inter-recombination to produce X2 (X = H or D). It is concluded that, under catalytic conditions, hydrogen surface recombination is much slower than ethylene hydrogenation and H-D exchange.

  16. [Characteristics of urea 15N absorption, allocation, and utilization by sweet-cherry (Prunus avium L.)].

    PubMed

    Zhao, Feng-Xia; Jiang, Yuan-Mao; Peng, Fu-Tian; Gao, Xiang-Bin; Liu, Bing-Hua; Wang, Hai-Yun; Zhao, Lin

    2008-03-01

    With five-year old 'Zaodaguo' sweet-cherry (Prunus avium L.) as test material, this paper studied the characteristics of its urea 15N absorption, allocation, and utilization when applied before bud-break. The results showed that the Ndff of different organs increased gradually with time, and was higher in fine roots and storage organs at full-blooming stage. At fruit core-hardening stage, the Ndff of long shoots and leaves increased quickly, reaching to 0.72% and 0.59% , respectively. From fruit core-hardening to harvesting stage, the Ndff of fruit had a rapid increase, with the peak (1.78%) at harvesting stage. After harvest, the Ndff of neonatal organs increased slowly while that of storage organs increased quickly. At full-blooming stage, the absorbed 15N in roots was firstly allocated to storage organs, with the highest allocation rate (54.91%) in large roots. At fruit core-hardening stage, the allocation rate in fine roots and storage organs decreased from 85.43% to 55.11%, while that in neonatal branches and leaves increased to 44.89%. At harvesting stage, the allocation rate in different organs had no significant change, but after harvest, the absorbed 15N had a rapid translocation to storage organs, and the allocation rate in fine roots and storage organs reached the highest (72.26%) at flower bud differentiation stage. The 15N allocation rate in neonatal branches and leaves at flower bud differentiation stage was decreased by 19.31%, compared with that at harvesting stage. From full-blooming to flower bud differentiation stage, the utilization rate of urea 15N was increasing, and reached the peak (16.86%) at flower bud differentiation stage.

  17. Pressure influence on the structural characteristics of modified absorptive glass mat separators: A standard contact porosimetry study

    NASA Astrophysics Data System (ADS)

    Burashnikova, M. M.; Khramkova, T. S.; Kazarinov, I. A.; Shmakov, S. L.

    2015-09-01

    The article presents a comparative analysis of the structural characteristics of absorptive glass mats manufactured by "Hollingsworth & Vose" (a 2.8 mm thickness) and "Bernard Dumas" (a 3.0 mm thickness) modified by impregnation with polymeric emulsions based on polyvinylidene fluoride, a polyvinylpyrrolidone styrene copolymer, and polytetrafluoroethylene, by means of standard contact porosimetry. The key study is influence of features of the porous structure on the compression properties, the rate of wicking, and the oxygen cycle efficiency in lead-acid battery mock-ups under several plate-group compression pressures. It is found that the treatment of the absorptive glass mat separators with polymeric emulsions leads to redistribution of their pores by size. An increased pressure in the electrode unit insignificantly changes the pore structure of the modified absorptive glass mat separators, and the oxygen cycle efficiency rises in comparison with unmodified separators.

  18. First calibration measurements of an FTIR absorption spectroscopy system for liquid hydrogen isotopologues for the isotope separation system of fusion power plants

    SciTech Connect

    Groessle, R.; Beck, A.; Bornschein, B.; Fischer, S.; Kraus, A.; Mirz, S.; Rupp, S.

    2015-03-15

    Fusion facilities like ITER and DEMO will circulate huge amounts of deuterium and tritium in their fuel cycle with an estimated throughput of kg per hour. One important capability of these fuel cycles is to separate the hydrogen isotopologues (H{sub 2}, D{sub 2}, T{sub 2}, HD, HT, DT). For this purpose the Isotope Separation System (ISS), using cryogenic distillation, as part of the Tritium Enrichment Test Assembly (TRENTA) is under development at Tritium Laboratory Karlsruhe. Fourier transform infrared absorption spectroscopy (FTIR) has been selected to prove its capability for online monitoring of the tritium concentration in the liquid phase at the bottom of the distillation column of the ISS. The actual research-development work is focusing on the calibration of such a system. Two major issues are the identification of appropriate absorption lines and their dependence on the isotopic concentrations and composition. For this purpose the Tritium Absorption IR spectroscopy experiment has been set up as an extension of TRENTA. For calibration a Raman spectroscopy system is used. First measurements, with equilibrated mixtures of H{sub 2}, D{sub 2} and HD demonstrate that FTIR can be used for quantitative analysis of liquid hydro-gen isotopologues and reveal a nonlinear dependence of the integrated absorbance from the D{sub 2} concentration in the second vibrational branch of D{sub 2} FTIR spectra. (authors)

  19. Characteristics of anomalous skin effect and evolution of power absorption regions in a cylindrical radio frequency inductively coupled plasma

    SciTech Connect

    Ding, Z. F.; Sun, B.; Huo, W. G.

    2015-06-15

    In a low-pressure radio-frequency (13.56 MHz), inductively coupled argon plasma generated by a normal cylindrical rf coil, electric field, current density, and absorbed power density is calculated from magnetic field measured with a phase-resolved magnetic probe. The anomalous skin effect (ASE) for the cylindrical rf coil is compared to those previously reported for the planar and re-entrant cylindrical rf coils. Physical reasons for our observed characteristics of ASE are presented. With the increasing discharge power, the size and the number of negative and positive power absorption regions evolve into several distinct patterns. For the low discharge power (at 156.9 W), there is one area of positive and one area of negative power absorption in the radial direction. For the medium discharge power (279 W–683.5 W), there are two areas of negative and two areas of positive power absorption. For the even higher discharge power (above 803.5 W), the number of areas is the same as that of the medium discharge power, but the size of the inner positive and negative power absorption areas is approximately doubled and halved, respectively, while the outer positive and negative power absorption areas slightly shrinks. The evolution of positive and negative power absorption regions is explained as a result of electron thermal diffusion and the energy conversion between rf current and electric field. The spatial decays of electric field and current density are also elucidated by linking them with the positive and negative power absorption pattern.

  20. Characteristics of anomalous skin effect and evolution of power absorption regions in a cylindrical radio frequency inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Ding, Z. F.; Sun, B.; Huo, W. G.

    2015-06-01

    In a low-pressure radio-frequency (13.56 MHz), inductively coupled argon plasma generated by a normal cylindrical rf coil, electric field, current density, and absorbed power density is calculated from magnetic field measured with a phase-resolved magnetic probe. The anomalous skin effect (ASE) for the cylindrical rf coil is compared to those previously reported for the planar and re-entrant cylindrical rf coils. Physical reasons for our observed characteristics of ASE are presented. With the increasing discharge power, the size and the number of negative and positive power absorption regions evolve into several distinct patterns. For the low discharge power (at 156.9 W), there is one area of positive and one area of negative power absorption in the radial direction. For the medium discharge power (279 W-683.5 W), there are two areas of negative and two areas of positive power absorption. For the even higher discharge power (above 803.5 W), the number of areas is the same as that of the medium discharge power, but the size of the inner positive and negative power absorption areas is approximately doubled and halved, respectively, while the outer positive and negative power absorption areas slightly shrinks. The evolution of positive and negative power absorption regions is explained as a result of electron thermal diffusion and the energy conversion between rf current and electric field. The spatial decays of electric field and current density are also elucidated by linking them with the positive and negative power absorption pattern.

  1. Triangulating the height of cosmic noise absorption: A method for estimating the characteristic energy of precipitating electrons

    NASA Astrophysics Data System (ADS)

    Wild, P.; Honary, F.; Kavanagh, A. J.; Senior, A.

    2010-12-01

    Energetic electrons (tens to hundreds of keV) deposit significant energy into the D layer of the ionosphere. Riometers provide a means of monitoring this electron precipitation by measuring the associated cosmic noise absorption (CNA), but individually they are incapable of resolving the associated energy. However, the combination of two imaging riometers with overlapping beams allows an estimate of the height of peak CNA and so the associated energy to be made. We examine two methods for estimating the height of CNA using data from two imaging riometers in northern Fennoscandia; a 3-D reconstruction of CNA using Occam's inversion and a technique based upon the triangulation of discrete absorption structures are developed. We compare these two methods with the results from a previously published technique. It is found that for the case studies and test phantoms the height triangulation and 3-D reconstruction offer improvement over previous methods. These techniques are tested by comparison with data from the EISCAT incoherent scatter radar. Observations show good correlation between the estimates of peak height of CNA from EISCAT and from the triangulation and 3-D reconstruction methods for this case. Three case studies are examined in detail, a slowly varying absorption, afternoon spike, and evening absorption spike event. Estimates of the characteristic energy are made. The substorm event had a characteristic energy of ˜5 keV, whereas the characteristic energy for the morning event was 17-20 keV. Analyses indicate the afternoon spike event having characteristic energy greater than 100 keV.

  2. Activation and deactivation of a robust immobilized Cp*Ir-transfer hydrogenation catalyst: a multielement in situ X-ray absorption spectroscopy study.

    PubMed

    Sherborne, Grant J; Chapman, Michael R; Blacker, A John; Bourne, Richard A; Chamberlain, Thomas W; Crossley, Benjamin D; Lucas, Stephanie J; McGowan, Patrick C; Newton, Mark A; Screen, Thomas E O; Thompson, Paul; Willans, Charlotte E; Nguyen, Bao N

    2015-04-01

    A highly robust immobilized [Cp*IrCl2]2 precatalyst on Wang resin for transfer hydrogenation, which can be recycled up to 30 times, was studied using a novel combination of X-ray absorption spectroscopy (XAS) at Ir L3-edge, Cl K-edge, and K K-edge. These culminate in in situ XAS experiments that link structural changes of the Ir complex with its catalytic activity and its deactivation. Mercury poisoning and "hot filtration" experiments ruled out leached Ir as the active catalyst. Spectroscopic evidence indicates the exchange of one chloride ligand with an alkoxide to generate the active precatalyst. The exchange of the second chloride ligand, however, leads to a potassium alkoxide-iridate species as the deactivated form of this immobilized catalyst. These findings could be widely applicable to the many homogeneous transfer hydrogenation catalysts with Cp*IrCl substructure.

  3. Extended x-ray-absorption and electron-energy-loss fine-structure studies of the local atomic structure of amorphous unhydrogenated and hydrogenated silicon carbide

    SciTech Connect

    Kaloyeros, A.E.; Rizk, R.B.; Woodhouse, J.B.

    1988-12-15

    Extended x-ray-absorption (EXAFS) and electron-energy-loss fine-structure (EXELFS) measurements have been performed on amorphous unhydrogenated silicon carbide, a-SiC, and amorphous hydrogenated silicon carbide, a-SiC:H. Two hydrogenated samples with hydrogen concentrations corresponding, respectively, to H flows of 4 sccm (20% of argon flow) and 8 sccm (40% of argon flow) during the reactive sputtering process, were analyzed (sccm denotes standard cubic centimeters per minute at STP). It is found that short-range order (SRO), consisting of the same tetrahedrally coordinated units present in cubic crystalline c-SiC (zinc-blende structure), where a Si atom is surrounded by nearly four C atoms and vice versa, does exist in all the amorphous samples. This SRO, however, is detected only at a level of the first C and Si coordination shells in a-SiC and a-SiC:H. The structural disorder of the first Si and C coordination shells in all forms of amorphous SiC is somewhat greater than c-SiC, and it decreases appreciably as hydrogen is added. The a-SiC sample exhibits large Si and C coordination numbers, almost identical to c-SiC, a low atomic density, and virtually the same Si-C bond length as c-SiC. These results indicate that a relatively small concentration of large voids exist in a highly disordered a-SiC matrix.

  4. Hydrogen peroxide decomposition rate: a shock tube study using tunable laser absorption of H(2)O near 2.5 microm.

    PubMed

    Hong, Zekai; Farooq, Aamir; Barbour, Ethan A; Davidson, David F; Hanson, Ronald K

    2009-11-19

    The thermal decomposition of hydrogen peroxide was measured behind reflected shock waves in hydrogen peroxide/inert gas mixtures using a sensitive laser diagnostic for water vapor. In these mixtures, the formation rate of water is predominantly controlled by the decomposition rate of hydrogen peroxide. Rate determinations were made over a temperature range of 1000-1200 K and a pressure range of 0.9-3.2 atm for both argon and nitrogen carrier gases. Good detection sensitivity for water was achieved using tunable diode laser absorption of water at 2550.96 nm within its v(3) fundamental band. Hydrogen peroxide decomposition rates were found to be independent of pressure at 0.9 and 1.7 atm and showed only slight influence of pressure at 3.2 atm. The best fit of the current data to the low-pressure-limit rate for H(2)O(2) dissociation in argon bath gas is k(1,0) = 10(15.97+/-0.10) exp(-21 220 +/- 250 K/T) [cm(3) mol(-1) s(-1)] (1000-1200 K). Experiments conducted in a nitrogen bath gas show a relative collision efficiency of argon to nitrogen of 0.67.

  5. Microwave absorption characteristics of the clouds of Venus from Mariner 10 radio occultation

    NASA Technical Reports Server (NTRS)

    Kliore, A. J.; Elachi, C.; Patel, I. R.; Way, J. B.

    1977-01-01

    Measurements of received signal strength at S-band (13 cm) and X-band (4.8 cm) wavelengths during the radio occultation of Mariner 10 by Venus on February 5, 1974, are examined in order to study the structure and composition of the absorbing medium. The frequency excursions of the signals are determined and used to obtain the structure of the refractive index in the lower atmosphere. Profiles of excess signal attenuation due to atmospheric scattering and absorption are presented which indicate that the X-band signal experienced much more absorption and was extinguished at about 50 km, while the S-band signal penetrated to about 42 km. The optical-depth data are inverted by means of a discrete inversion method to obtain the absorption coefficient for each band as a function of height, and the resulting absorption-coefficient profiles are compared with the attenuation at vertical incidence modeled from planetary radar and passive microwave observations of Venus. The absorption coefficients at the two wavelengths are employed to estimate the liquid content and composition of the microwave-absorbing cloud particles.

  6. Characteristics of Hydrogen Negative Ion Source with FET based RF System

    SciTech Connect

    Ando, A.; Matsuno, T.; Funaoi, T.; Tanaka, N.; Tsumori, K.; Takeiri, Y.

    2011-09-26

    Characteristics of radio frequency (RF) plasma production were investigated using a FET inverter power supply as a RF generator. High density hydrogen plasma was obtained using an external coil wound a cylindrical ceramic tube (driver region) with RF frequency of lower than 0.5 MHz. When an axial magnetic field around 10 mT was applied to the driver region, an electron density increased drastically and attained to over 10{sup 19} m{sup -3} in the driver region. Effect of the axial magnetic field in driver and expansion region was examined. Lower gas pressure operation below 0.5 Pa was possible with higher RF frequency. H{sup -} density in the expansion region was measured by using laser photo-detachment system. It decreased as the axial magnetic field applied, which was caused by the increase of energetic electron from the driver.

  7. Optical nonlinear absorption characteristics of Sb{sub 2}Se{sub 3} nanoparticles

    SciTech Connect

    Muralikrishna, Molli Kiran, Aditha Sai Ravikanth, B. Sowmendran, P. Muthukumar, V. Sai Venkataramaniah, Kamisetti

    2014-04-24

    In this work, we report for the first time, the nonlinear optical absorption properties of antimony selenide (Sb{sub 2}Se{sub 3}) nanoparticles synthesized through solvothermal route. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies revealed that the nanoparticles are in the range of 10 - 40 nm. Elemental analysis was performed using EDAX. By employing open aperture z-scan technique, we have evaluated the effective two-photon absorption coefficient of Sb{sub 2}Se{sub 3} nanoparticles to be 5e-10 m/W at 532 nm. These nanoparticles exhibit strong intensity dependent nonlinear optical absorption and hence could be considered to have optical power limiting applications in the visible range.

  8. Absorption spectroscopy setup for determination of whole human blood and blood-derived materials spectral characteristics

    NASA Astrophysics Data System (ADS)

    Wróbel, M. S.; Gnyba, M.; Milewska, D.; Mitura, K.; Karpienko, K.

    2015-09-01

    A dedicated absorption spectroscopy system was set up using tungsten-halogen broadband source, optical fibers, sample holder, and a commercial spectrometer with CCD array. Analysis of noise present in the setup was carried out. Data processing was applied to the absorption spectra to reduce spectral noise, and improve the quality of the spectra and to remove the baseline level. The absorption spectra were measured for whole blood samples, separated components: plasma, saline, washed erythrocytes in saline and human whole blood with biomarkers - biocompatible nanodiamonds (ND). Blood samples had been derived from a number of healthy donors. The results prove a correct setup arrangement, with adequate preprocessing of the data. The results of blood-ND mixtures measurements show no toxic effect on blood cells, which proves the NDs as a potential biocompatible biomarkers.

  9. [Analysis of dynamic characteristics for fermentative hydrogen-producing bacteria community and hydrogen producing capability in CSTR].

    PubMed

    Song, Jia-Xiu; Ren, Nan-Qi; Chen, Ying; An, Dong

    2009-07-15

    The start into the types of fermentation was carried out by pH adjustment from 4.2 to 6.0 in CSTR system. The process of transforming of hydrogen production and dynamic community of bacteria were studied. The results showed that with the organic load maintained at (33 +/- 1) kg/(m3 x d), there was no change in 10 d for the type of fermentation, the amount of hydrogen does not reduce in 8 d. After 15 d, the system was transformed from the ethanol-based type into butyric acid type and water alkalinity was from 250 mg/L to 2450 mg/L. The use of fluorescence in situ hybridization (FISH) system was in response to the 3 groups of micro-organisms. It was found that in the process of transforming, Clostridium cluster XI increases and Clostridium cluster I and II decreases. Enterobacteriaceae always existed with no change. The microbial growth must be considered with hydrogen production capability. The average hydrogen production rate reached to 23.6 mol/(kg x d) with Clostridium cluster I and II dominated in fermentation reactor.

  10. Phytoplankton pigment and absorption characteristics along meridional transects in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Barlow, R. G.; Aiken, J.; Holligan, P. M.; Cummings, D. G.; Maritorena, S.; Hooker, S.

    2002-04-01

    Pigment patterns and associated absorption properties of phytoplankton were investigated in the euphotic zone along two meridional transects in the Atlantic Ocean, between the UK and the Falkland Islands, and between South Africa and the UK. Total chlorophyll a (TChla=MVChla+DVChla+chlorophyllide a) concentrations and the biomarker pigments for diatoms (fucoxanthin), nanoflagellates and cyanobacteria (zeaxanthin) appeared to have similar distribution patterns in the spring and in the autumn in the temperate NE Atlantic and the northern oligotrophic gyre. Divinyl chlorophyll a levels (prochlorophytes) were greater in spring at the deep chlorophyll maximum in the oligotrophic gyre, however. Marked seasonal differences were observed in the NW African upwelling region. TChla concentrations were twice as high in the upper mixed layer in the spring, with the community dominated by diatoms and prymnesiophytes (19'-hexanoyloxyfucoxanthin). A layered structure was prevalent in the autumn where cyanobacteria, diatoms and prymnesiophytes were located in the upper water column and diatoms and mixed nanoflagellates at the sub-surface maximum. In the South Atlantic, the Benguela upwelling ecosystem and the Brazil-Falklands Current Confluence Zone (BFCCZ) were the most productive regions with the TChla levels being twice as high in the Benguela. Diatoms dominated the Benguela system, while nanoflagellates were the most ubiquitous group in the BFCCZ. Pigment concentrations were greater along the eastern boundary of the southern oligotrophic gyre and distributed at shallower depths. Deep chlorophyll maxima were a feature of the western boundary oligotrophic waters, and cyanobacteria tended to dominate the upper water column along both transects with a mixed group of nanoflagellates at the chlorophyll maximum. Absorption coefficients were estimated from spectra reconstructed from pigment data. Although absorption was greater in the productive areas, the TChla-specific coefficients

  11. Shock tube study on the thermal decomposition of fluoroethane using infrared laser absorption detection of hydrogen fluoride.

    PubMed

    Matsugi, Akira; Shiina, Hiroumi

    2014-08-28

    Motivated by recent shock tube studies on the thermal unimolecular decomposition of fluoroethanes, in which unusual trends have been reported for collisional energy-transfer parameters, the rate constants for the thermal decomposition of fluoroethane were investigated using a shock tube/laser absorption spectroscopy technique. The rate constants were measured behind reflected shock waves by monitoring the formation of HF by IR absorption at the R(1) transition in the fundamental vibrational band near 2476 nm using a distributed-feedback diode laser. The peak absorption cross sections of this absorption line have also been determined and parametrized using the Rautian-Sobel'man line shape function. The rate constant measurements covered a wide temperature range of 1018-1710 K at pressures from 100 to 290 kPa, and the derived rate constants were successfully reproduced by the master equation calculation with an average downward energy transfer, ⟨ΔEdown⟩, of 400 cm(-1).

  12. Defect assisted saturable absorption characteristics in Al and Li doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    K. M., Sandeep; Bhat, Shreesha; S. M., Dharmaprakash; P. S., Patil; Byrappa, K.

    2016-09-01

    The influence of different doping ratios of Al and Li on the nonlinear optical properties, namely, a two-photon absorption and a nonlinear refraction using single beam Z-scan technique, of nano-crystalline ZnO thin films has been investigated in the present study. A sol-gel spin-coated pure ZnO, Al-doped ZnO (AZO), and Li-doped ZnO (LZO) thin films have been prepared. The stoichiometric deviations induced by the occupancy of Al3+ and Li+ ions at the interstitial sites injects the compressive stress in the AZO and LZO thin films, respectively, while the extended defect states below the conduction band leads to a redshift of energy band gap in the corresponding films as compared to pure ZnO thin film. Switching from an induced absorption in ZnO and 1 at. wt. % doped AZO and LZO films to a saturable absorption (SA) in 2 at. wt. % doped AZO and LZO films has been observed, and it is attributed to the saturation of a linear absorption of the defect states. The closed aperture Z-scan technique revealed the self-focusing (a positive nonlinear refractive index) in all the films, which emerge out of the thermo-optical effects due to the continuous illumination of laser pulses. A higher third-order nonlinear optical susceptibility χ(3) of the order 10-3 esu has been observed in all the films.

  13. Polarization and bonding of the intrinsic characteristic contours of hydrogen and fluorine atoms of forming a hydrogen fluoride molecule based on an ab initio study

    NASA Astrophysics Data System (ADS)

    Yang, Zhong-Zhi; Zhao, Dong-Xia; Wu, Yang

    2004-08-01

    The spatial changing feature of the shapes and sizes of the system consisted of one hydrogen atom and one fluorine atom of forming a hydrogen fluoride molecule is investigated. We give formalism of the potential acting on an electron in a molecule and derive its concrete expression in Hartree-Fock self-consistent molecular orbital theory including configuration interaction. The program of calculating the potential acting on an electron in a molecule is programmed and compiled in the framework of the MELD program package. We formulate briefly the approach of the molecular intrinsic characteristic contour (MICC) which is defined in terms of the classical turning points of electronic motion. The MICC for a molecular system is intrinsic and can be calculated by means of an ab initio CI method. Then, the polarization and bonding features of the intrinsic characteristic contours of hydrogen and fluorine atoms forming a hydrogen fluoride molecule are presented and discussed from ab initio calculations. Furthermore, electron density distribution as an added dimension has been demonstrated on the changing MICC and thus the vivid polarization and bonding features for a chemical process have been shown. It seems that at the early stage (internuclear distance Ind=5.0-20.0 a.u.) the fluorine atom gives more enthusiastic with the sensitive and expanded polarization to welcome coupling with the hydrogen atom while the latter has little response even "shy" with shrinking a bit its size at the beginning of putting the two atoms into a system and it is only around the critical point, the contact point (Ind=4.73 a.u.), that both of them stretch their hands and arms to meet and then fuse together.

  14. Improved characteristics of amorphous indium-gallium-zinc-oxide-based resistive random access memory using hydrogen post-annealing

    SciTech Connect

    Kang, Dae Yun; Lee, Tae-Ho; Kim, Tae Geun

    2016-08-15

    The authors report an improvement in resistive switching (RS) characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO)-based resistive random access memory devices using hydrogen post-annealing. Because this a-IGZO thin film has oxygen off-stoichiometry in the form of deficient and excessive oxygen sites, the film properties can be improved by introducing hydrogen atoms through the annealing process. After hydrogen post-annealing, the device exhibited a stable bipolar RS, low-voltage set and reset operation, long retention (>10{sup 5 }s), good endurance (>10{sup 6} cycles), and a narrow distribution in each current state. The effect of hydrogen post-annealing is also investigated by analyzing the sample surface using X-ray photon spectroscopy and atomic force microscopy.

  15. Improved characteristics of amorphous indium-gallium-zinc-oxide-based resistive random access memory using hydrogen post-annealing

    NASA Astrophysics Data System (ADS)

    Kang, Dae Yun; Lee, Tae-Ho; Kim, Tae Geun

    2016-08-01

    The authors report an improvement in resistive switching (RS) characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO)-based resistive random access memory devices using hydrogen post-annealing. Because this a-IGZO thin film has oxygen off-stoichiometry in the form of deficient and excessive oxygen sites, the film properties can be improved by introducing hydrogen atoms through the annealing process. After hydrogen post-annealing, the device exhibited a stable bipolar RS, low-voltage set and reset operation, long retention (>105 s), good endurance (>106 cycles), and a narrow distribution in each current state. The effect of hydrogen post-annealing is also investigated by analyzing the sample surface using X-ray photon spectroscopy and atomic force microscopy.

  16. Local order in hydrogenated amorphous germanium thin films studied by extended x-ray absorption fine-structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Dalba, G.; Fornasini, P.; Grisenti, R.; Rocca, F.; Chambouleyron, I.; Graeff, C. F. O.

    1997-07-01

    The effect of hydrogenation on the local order in amorphous germanium has been studied by EXAFS. Measurements have been carried out on sputtered a-Ge:H films with hydrogen concentrations of 0, 7, 10, and 15 at.%, as a function of temperature in the range 11 - 300 K. The first-shell EXAFS data were analysed by the ratio method based on cumulant expansion. The asymmetric distributions reconstructed from cumulants are in very good agreement with a parametrized distribution obtained by other researchers using calculated phase-shifts. For the unhydrogenated a-Ge (deposited at 0953-8984/9/27/017/img7), increases of the interatomic distance, 0953-8984/9/27/017/img8 at 11 K, static disorder, 0953-8984/9/27/017/img9, and thermal disorder, 0953-8984/9/27/017/img10, have been found with respect to those for c-Ge. Both the static and the thermal disorder are smaller than for an evaporated sample (deposited at 0953-8984/9/27/017/img11) previously studied. The insertion of hydrogen in a-Ge produces a sharp reduction of the interatomic distance, static disorder, and asymmetry of the distribution already at the lowest H concentration (7%); then these parameters decrease almost linearly when the hydrogen content increases. No appreciable influence of hydrogenation on the thermal disorder has been detected.

  17. Study of gain and photoresponse characteristics for back-illuminated separate absorption and multiplication GaN avalanche photodiodes

    SciTech Connect

    Wang, Xiaodong; Pan, Ming; Hou, Liwei; Xie, Wei; Hu, Weida Xu, Jintong; Li, Xiangyang; Chen, Xiaoshuang Lu, Wei

    2014-01-07

    The gain and photoresponse characteristics have been numerically studied for back-illuminated separate absorption and multiplication (SAM) GaN avalanche photodiodes (APDs). The parameters of fundamental models are calibrated by simultaneously comparing the simulated dark and light current characteristics with the experimental results. Effects of environmental temperatures and device dimensions on gain characteristics have been investigated, and a method to achieve the optimum thickness of charge layer is obtained. The dependence of gain characteristics and breakdown voltage on the doping concentration of the charge layer is also studied in detail to get the optimal charge layer. The bias-dependent spectral responsivity and quantum efficiency are then presented to study the photoresponse mechanisms inside SAM GaN APDs. It is found the responsivity peak red-shifts at first due to the Franz-Keldysh effect and then blue-shifts due to the reach-through effect of the absorption layer. Finally, a new SAM GaN/AlGaN heterojunction APD structure is proposed for optimizing SAM GaN APDs.

  18. Hydrogen bonding between acetate-based ionic liquids and water: Three types of IR absorption peaks and NMR chemical shifts change upon dilution

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Cao, Yuanyuan; Zhang, Yuwei; Mu, Tiancheng

    2014-01-01

    The hydrogen-bonding interaction between acetate-based ionic liquids (AcIL) and water was investigated by attenuated total reflection infrared (ATR-IR) and 1H NMR. Interestingly, the relative change of chemical shift δ of 1H NMR upon dilution could be divided into three regions. All the H show an upfield shift in Regions 1 and 2 while a different tendency in Region 3 (upfield, no, and downfield shift classified as Types 1, 2, 3, respectively). For ATR-IR, the red, no, or blue shift of νOD (IR absorption peak of OD in D2O) and ν± (IR absorption peak of AcILs) also have three types, respectively. Two-Times Explosion Mechanism (TTEM) was proposed to interpret the dynamic processes of AcILs upon dilution macroscopically, meanwhile an Inferior Spring Model (ISM) was proposed to help to understand the TTEM microscopically, All those indicate that AcILs present the state of network, sub-network, cluster, sub-cluster, ion pairs and sub-ion pairs in sequence upon dilution by water and the elongation of hydrogen bonding between AcILs-water, between cation-anion of AcILs is plastic deformation rather than elastic deformation.

  19. Collision-Induced Absorption Spectra of Binary Mixtures of Molecular Hydrogen with Molecular Deuterium and Argon and of Pure Hydrogen, D

    NASA Astrophysics Data System (ADS)

    Hsieh, Chang-Tsang William

    In the present research project a systematic study of the collision-induced infrared absorption (CIA) spectra of the binary mixtures of H_2 - D_2 in the region of the double fundamental vibrations of H_2 and D_2, and H_2 - Ar in the fundamental band of H_2, and of pure HD in its fundamental and first overtone regions was undertaken. The experiments were carried out with a 2.0 m high-pressure low-temperature transmission-type absorption cell at 77, 201 and 296 K at total gas densities up to 550 amagat. Infrared prism and grating spectrometers equipped with a microprocessor -controlled stepping motor were used to record the spectra. All the experimental results obtained represent first-time observations in collision-induced absorption. Collision-induced infrared absorption spectra of the double transitions of H_2(v=1>=ts 0) and D_2(v=1>=ts 0) have been observed at 77 and 201 K in the spectral region 7000-8000 cm^{-1} for total gas densities up to 550 amagat with a partial gas density ratio of 1:1 of H_2 and D_2. The observed spectra are interpreted in terms of the transitions, Q_1(J) of H_2+Q_1(J) of D _2, Q_1(J) of H_2+S _1(J) of D_2, S_1(J) of H_2 + Q_1(J) of D_2, and S_1(J) of H_2 + S_1(J) of D_2 for J = 0 and 1 for H _2 and J = 0, 1, and 2 for D_2. Analysis of the experimental absorption profiles was carried out using appropriate lineshape functions. The absorption coefficients, lineshape parameters, etc., are obtained from the analysis. Collision-induced enhancement absorption spectra of the fundamental band of H_2 in H_2 - Ar mixtures were recorded at room temperature for a base density of 72 amagat of H_2 for several partial densities of Ar up to 440 amagat. Hexadecapole-induced U transitions, U_1(1), U_1(2), Q_1(0)+U _0(1), and Q_1(1) + U_0(1) have been identified in the spectral region 5400 -6200 cm^{-1}. A "cage" model has been proposed to account for the double transitions of H_2 - H_2 in the H _2 - Ar enhancement spectra. From the analysis of the

  20. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores.

    PubMed

    Pandit, Deepak Kr; Kundu, Santimoy; Gupta, Shishir

    2017-02-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively.

  1. Removal characteristics of CO2 using aqueous MEA/AMP solutions in the absorption and regeneration process.

    PubMed

    Choi, Won-Joon; Seo, Jong-Beom; Jang, Sang-Yong; Jung, Jong-Hyeon; Oh, Kwang-Joong

    2009-01-01

    The carbon dioxide (CO2) removal efficiency, reaction rate, and CO2 loading into aqueous blended monoethanolamine (MEA) + 2-amino-2-methyl-1-propanol (AMP) solutions to enhance absorption characteristics of MEA and AMP were carried out by the absorption/regeneration process. As a result, compared to aqueous MEA and AMP solutions, aqueous blended MEA + AMP solutions have a higher CO2 loading than MEA and a higher reaction rate than AMP. The CO2 loading of rich amine of aqueous 18 wt.% MEA + 12 wt.% AMP solution was 0.62 mol CO2/mol amine, which is 51.2% more than 30 wt.% MEA (0.41 mol CO2/mol amine). Consequently, blending MEA and AMP could be an effective way to design considering economical efficiency and used to operate absorber for a long time.

  2. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores

    NASA Astrophysics Data System (ADS)

    Pandit, Deepak Kr.; Kundu, Santimoy; Gupta, Shishir

    2017-02-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively.

  3. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores

    PubMed Central

    Kundu, Santimoy; Gupta, Shishir

    2017-01-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively. PMID:28386416

  4. Mg II Absorption Characteristics of a Volume-Limited Sample of Galaxies at z ~ 0.1

    NASA Astrophysics Data System (ADS)

    Barton, Elizabeth J.; Cooke, Jeff

    2009-12-01

    We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z ~ 0.1), luminous (M r + 5log h <=-20.5) galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z gsim 0.1 and the presence of an appropriate bright background quasar within a projected 75 h -1 kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W eq(2796) >= 0.3 Å) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W eq(2796) >= 1-2 Å) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction fc lsim 0.4 for >=0.3 Å absorbers at z ~ 0.1, even at impact parameters <=35 h -1 kpc (f c ~ 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  5. Mg II ABSORPTION CHARACTERISTICS OF A VOLUME-LIMITED SAMPLE OF GALAXIES AT z {approx} 0.1

    SciTech Connect

    Barton, Elizabeth J.; Cooke, Jeff E-mail: cooke@uci.edu

    2009-12-15

    We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z {approx} 0.1), luminous (M {sub r} + 5log h {<=}-20.5) galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z {approx}> 0.1 and the presence of an appropriate bright background quasar within a projected 75 h {sup -1} kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W {sub eq}(2796) {>=} 0.3 A) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W {sub eq}(2796) {>=} 1-2 A) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction f{sub c} {approx}< 0.4 for {>=}0.3 A absorbers at z {approx} 0.1, even at impact parameters {<=}35 h {sup -1} kpc (f {sub c} {approx} 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy.

  6. Discovery of neutral hydrogen 21 centimeter absorption at redshift 0.25 toward PKS 1413+135

    NASA Technical Reports Server (NTRS)

    Carilli, C. L.; Perlman, Eric S.; Stocke, John T.

    1992-01-01

    A strong H I 21-cm absorption line is identified toward PKS 1413+135 at the redshift of the host galaxy and argued to indicate that the IR-optical cutoff of the BL Lac object's spectrum is caused by extinction. The BL Lac object is shown to have strong neutral 21-cm absorption at the redshift range z = 0.24671 +/- 0.00001, and the implied H I column density is derived. The H I covering factor is assumed to be not more than 0.1, suggesting that a high degree of extinction exists in the galaxy. The host galaxy is theorized to be a spiral of type later than S0 based on the redshift of the H I absorption line and the host. The statistical and observational conclusions are found to support the theories of Stock et al. (1992) regarding the red spectrum of the object.

  7. Scattering and absorption characteristics of atmospheric aerosols over a semi-urban coastal environment

    NASA Astrophysics Data System (ADS)

    Aruna, K.; Lakshmi Kumar, T. V.; Rao, D. Narayana; Krishna Murthy, B. V.; Babu, S. Suresh; Krishnamoorthy, K.

    2014-11-01

    The scattering and absorption components of Aerosol Optical Depth (AOD) over a semi-urban coastal location (12.81°N, 80.03°E) near the mega city Chennai in peninsular India are separated using the collocated measurements of Black Carbon concentration and Atmospheric Boundary Layer Height (ABLH) from ERA Interim Reanalysis data assuming that most of the BC is contained and homogeneously mixed in the ABL. It is found that the absorption component to scattering component ratio has a strong seasonal variation with a pronounced maximum in the South West (SW) monsoon season. This is indicative of more effective wet removal of scattering aerosols than absorbing (BC) aerosols. There could also be an effect due to preferential removal of large particles which would have a lower content of BC. The Angstrom wavelength exponent shows a minimum in the SW monsoon season, the minimum being more pronounced for the scattering aerosols implying relative dominance of coarse mode particles. Investigation of the effect of Relative Humidity on scattering and absorption components of AOD revealed that the BC (absorbing) aerosols are non-hydrophilic/not coated with hydrophilic substance.

  8. Absorption and emission characteristics of Er3+ ions in alkali chloroborophosphate glasses.

    PubMed

    Moorthy, L R; Rao, T S; Janardhnam, K; Radhapathy, A

    2000-08-01

    Alkali chloroborophosphate glasses containing 1 mol% of Er3+ ions were studied experimentally using the absorption and emission spectroscopy. The energy level scheme for the 4f11 (Er3+) electronic configuration was deduced from the observed band energies of the absorption spectra in terms of a parametrized Hamiltonian using the various free-ion spectroscopic parameters. Oscillator strengths (f) measured from the absorption spectra have been analyzed using the Judd-Ofelt theory to evaluate the three intensity parameters omegalambda (lambda = 2, 4 and 6). Reasonable agreement between the measured and calculated f values has been found. Electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission cross sections and radiative lifetimes were calculated for all the excited states of Er3+ ions. The non-radiative (WNR) relaxation rates from the excited levels to the next lower levels have been calculated and the relationship between the energy gap and non-radiative relaxation rate has been established. These results were used to predict the possible potential laser transitions in Er-doped alkali chloroborophosphate glasses.

  9. Terahertz Absorption Characteristics of NiCr Film and Enhanced Absorption by Reactive Ion Etching in a Microbolometer Focal Plane Array

    NASA Astrophysics Data System (ADS)

    Gou, Jun; Wang, Jun; Li, Weizhi; Tai, Huiling; Gu, Deen; Jiang, Yadong

    2013-08-01

    Nano - scale metallic films have been proven to be an effective terahertz (THz) absorption layer in uncooled infrared (IR) microbolometers operated in THz spectral range. Optimized absorption can be achieved by adjusting the thickness of metallic film. Nickel - chromium (NiCr) thin films are deposited on the diaphragms of 320 × 240 VOx - based infrared focal plane arrays (IRFPA). Absorption measurements of the diaphragms with different thicknesses of NiCr (5 to 40 nm) agree reasonably well with the predicted absorption. To improve THz absorption further, a reactive ion etching (RIE) process applied to the dielectric support layer is first suggested, which generates nano - scale surface structures and increases the effective surface area of NiCr absorption film. This provides an effective way which is easy to accomplish and compatible with the manufacturing process of microbolometer IRFPAs to improve THz absorption and detection sensitivity.

  10. Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications

    NASA Technical Reports Server (NTRS)

    Barbi, E.; Mahan, J. R.; O'Brien, W. F.; Wagner, T. C.

    1989-01-01

    The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated.

  11. Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications

    SciTech Connect

    Barbi, E.; Mahan, J.R.; O'brien, W.F.; Wagner, T.C.

    1989-04-01

    The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated. 10 references.

  12. [Absorption Characteristics of Particulates and CDOM in Waters of Chagan Lake and Xinlicheng Reservoir in Autumn].

    PubMed

    Li, Si-jia; Song, Kai-shan; Zhao, Ying; Mu, Guang-yi; Shao, Tian-tian; Ma, Jian-hang

    2016-01-15

    Field surveys and laboratory analysis were carried out in Chagan Lake and Xinlicheng Reservoir under different salinity conditions in September 2012. In the laboratory, the absorption coefficients of particulates and chromophoric dissolved organic matter (CDOM) were measured, aiming to compare the absorption features, source of optical active substances and relative contribution of optical active constituents over the range of PAR (400-700 nm) in Chagan Lake and Xinlicheng Reservoir. The results showed that the Chagan Lake and Xinlicheng Reservoir were water bodies with medium eutrophication in autumn by TAL nutrient index and the absorption spectra of particulates matters were similar to those of phytoplankton. For the Chagan Lake with high salinity( EC = 988. 87 micro S x cm(-1)), the total particulate absorption was dominated by the nonalgal particles, and the contribution rate was in the order of nonalgal particles > phytoplankton > CDOM. For the Xinlicheng Reservoir with low salinity (EC = 311.67 microS x -cm(-1)), the total particulate absorption was dominated by the phytoplankton, and the contribution rate was ranked as phytoplankton > nonalgal particles > CDOM. Positive correlation was observed between a(p) (440), a(p) (675), a(d) (440) and total suspended matter (TSM), inorganic suspended matter (ISM), organic suspended matter (OSM) and Chl-a respectively in Chagan Lake, with correlation coefficients all above 0.55. Positive correlation was observed between a(p)(440), a(p) (675) and Chl-a (0.77 and 0.85, P < 0.05) , so did a(d) (440) and ISM (0.74, P < 0.01), while negative correlation was observed between a(p) (440) and OSM in the Xinlicheng Reservoir. In terms of Chagan Lake, negative correlation was merely observed between a(g) (440) and OSM (-0.54, P < 0.05) , but not in the Xinlicheng Reservoir. Both Sg, which was calculated by the fitting absorption curve from 250 to 400 nm, and relative molecular weight M showed that Sg[ (0.021 +/- 0.001) m(-1)] in

  13. Suicide Fads: Frequency and Characteristics of Hydrogen Sulfide Suicides in the United States

    PubMed Central

    Reedy, Sarah Jane D.; Schwartz, Michael D.; Morgan, Brent W.

    2011-01-01

    Objective: To assess the frequency of hydrogen sulfide (H2S) suicides and describe the characteristics of victims in the United States (U.S.) since the technique became common in Japan in 2007. Methods: To ascertain the frequency of intentional H2S related deaths in the U.S. prior to the start of the Japanese trend in 2007, we searched the multiple-cause-of-death data from the National Vital Statistics System. To collect as much information about the victims as possible, we sent an email to the National Association of Medical Examiners (NAME) listserv asking for their cooperation in identifying cases of H2S suicide. To identify cases that were not voluntarily reported by medical examiners but were reported by the media, we conducted Google searches using the search terms: “hydrogen sulfide suicide,” “H2S suicide,” “detergent suicide,” “chemical suicide,” and “suicide fad.” We obtained all available autopsy reports and abstracted information, including the site of the incident, the presence of a note warning others about the toxic gas and the demographic characteristics of the victims. We contacted medical examiners who potentially had custody of the cases that were identified through media reports and requested autopsies of these victims. When unable to obtain the autopsies, we gathered information from the media reports. Results: Forty-five deaths from H2S exposure occurred in the U.S. from 1999 to 2007, all unintentional. Responses from the NAME listserv yielded autopsy reports for 11 victims, and Google searches revealed an additional 19 H2S suicides in the U.S. since 2008. Overall (n=30), two cases were identified during 2008, 10 in 2009, and 18 in 2010. The majority of victims were white males, less than 30-years-old, left a warning note, and were found in cars. There were five reports of injuries to first responders, but no secondary fatalities. Conclusion: H2S suicides are increasing in the U.S., and their incidence is probably

  14. Effect of hydrogen on ethanol-biodiesel blend on performance and emission characteristics of a direct injection diesel engine.

    PubMed

    Parthasarathy, M; Isaac JoshuaRamesh Lalvani, J; Dhinesh, B; Annamalai, K

    2016-12-01

    Environment issue is a principle driving force which has led to a considerable effort to develop and introduce alternative fuels for transportation. India has large potential for production of biofuels like biodiesel from vegetable seeds. Use of biodiesel namely, tamanu methyl ester (TME) in unmodified diesel engines leads to low thermal Efficiency and high smoke emission. To encounter this problem hydrogen was inducted by a port fueled injection system. Hydrogen is considered to be low polluting fuel and is the most promising among alternative fuel. Its clean burning characteristic and better performance attract more interest compared to other fuels. It was more active in reducing smoke emission in biodiesel. A main drawback with hydrogen fuel is the increased NOx emission. To reduce NOx emission, TME-ethanol blends were used in various proportions. After a keen study, it was observed that ethanol can be blended with biodiesel up to 30% in unmodified diesel engine. The present work deals with the experimental study of performance and emission characteristic of the DI diesel engine using hydrogen and TME-ethanol blends. Hydrogen and TME-ethanol blend was used to improve the brake thermal efficiency and reduction in CO, NOx and smoke emissions.

  15. A study on transmission characteristics and specific absorption rate using impedance-matched electrodes for various human body communication.

    PubMed

    Machida, Yuta; Yamamoto, Takahiko; Koshiji, Kohji

    2013-01-01

    Human body communication (HBC) is a new communication technology that has presented potential applications in health care and elderly support systems in recent years. In this study, which is focused on a wearable transmitter and receiver for HBC in a body area network (BAN), we performed electromagnetic field analysis and simulation using the finite difference time domain (FDTD) method with various models of the human body. Further we redesigned a number of impedance-matched electrodes to allow transmission without stubs or transformers. The specific absorption rate (SAR) and transmission characteristics S21 of these electrode structures were compared for several models.

  16. Diversity in the Visible-NIR Absorption Band Characteristics of Lunar and Asteroidal Plagioclase

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Kaiden, H.; Misawa, K.; Kojima, H.; Uemoto, K.; Ohtake, M.; Arai, T.; Sasaki, S.; Takeda, H.; Nyquist, L. E.; Shih, C.-Y.

    2012-01-01

    Studying the visible and near-infrared (VNIR) spectral properties of plagioclase has been challenging because of the difficulty in obtaining good plagioclase separates from pristine planetary materials such as meteorites and returned lunar samples. After an early study indicated that the 1.25 m band position of plagioclase spectrum might be correlated with the molar percentage of anorthite (An#) [1], there have been few studies which dealt with the band center behavior. In this study, the VNIR absorption band parameters of plagioclase samples have been derived using the modified Gaussian model (MGM) [2] following a pioneering study by [3].

  17. Moisture absorption characteristics of the Orbiter thermal protection system and methods used to prevent water ingestion

    NASA Technical Reports Server (NTRS)

    Schomburg, C.; Dotts, R. L.; Tillian, D. J.

    1983-01-01

    The Space Shuttle Orbiter's silica tile Thermal Protection System (TPS) is beset by the moisture absorption problems inherently associated with low density, highly porous insulation systems. Attention is presently given to the comparative success of methods for the minimization and/or prevention of water ingestion by the TPS tiles, covering the development of water-repellent agents and their tile application techniques, flight test program results, and materials improvements. The use of external films for rewaterproofing of the TPS tiles after each mission have demonstrated marginal to unacceptable performance. By contrast, a tile interior waterproofing agent has shown promise.

  18. Characteristics of aerosol light scattering and absorption properties observed at Gosan, Korea, during GOPOEX 2014

    NASA Astrophysics Data System (ADS)

    Cho, C.; Kim, S. W.; Sheridan, P. J.; Gustafsson, O.; Lee, M.; Yoon, S. C.

    2016-12-01

    Anthropogenic fine pollution and wind-blown mineral dust aerosols have a significant effect on the regional radiation budget by scattering or absorbing the solar radiation reaching the Earth's surface. We investigate the optical and physical properties of dust and pollution aerosols at Gosan Climate Observatory (GCO), Korea during Gosan Pollution Experiment 2014 (GOPOEX 2014; January 2014).Mean values of aerosol scattering coefficient and absorption coefficient during GOPOEX 2014 were 72 ± 86 Mm-1 and 6 ± 5 Mm-1 at 550 nm, respectively. Aerosol scattering coefficient and absorption coefficient during dust episodes were 245 ± 171 Mm-1 and 22 ± 13 Mm-1 at 550 nm, which were approximately 3.5 times greater than mean values during GOPOEX 2014. Values for scattering and absorption coefficient of pollution episodes were recorded as 153 ± 95 Mm-1 and 12 ± 7 Mm-1 at 550 nm. Therefore, single scattering albedo of pollution episodes (0.92 ± 0.02) was slightly higher than those of dust episodes (0.90 ± 0.03). This is because that pollutant aerosols include more scattering fraction such as SO42-, and NO3- in fine particulate matter emitted from industrial areas in the eastern coastal region of China while dust aerosols are transported from North China to Gosan.Aerosol optical properties are influenced by where the air mass is transported from, either South China or North China. The mean values of aerosol scattering coefficient and absorption coefficient when air mass was transported from South China were 136 ± 132 Mm-1 and 15 ± 14 Mm-1 at 550 nm whereas those from North China were 108 ± 112 Mm-1 and 8 ± 7 Mm-1 at 550 nm. Single scattering albedo are almost identical as 0.9 ± 0.03 for both air masses.Carbonaceous composition of aerosols, which occupy a considerable fraction of fine particulate matter, also depends on the origin of the air mass. Radiocarbon (14C) is a good indicator for distinguishing between fossil combustion and biomass combustion. Detailed source

  19. Hydrogen sulfide decreases β-adrenergic agonist-stimulated lung liquid clearance by inhibiting ENaC-mediated transepithelial sodium absorption.

    PubMed

    Agné, Alisa M; Baldin, Jan-Peter; Benjamin, Audra R; Orogo-Wenn, Maria C; Wichmann, Lukas; Olson, Kenneth R; Walters, Dafydd V; Althaus, Mike

    2015-04-01

    In pulmonary epithelia, β-adrenergic agonists regulate the membrane abundance of the epithelial sodium channel (ENaC) and, thereby, control the rate of transepithelial electrolyte absorption. This is a crucial regulatory mechanism for lung liquid clearance at birth and thereafter. This study investigated the influence of the gaseous signaling molecule hydrogen sulfide (H2S) on β-adrenergic agonist-regulated pulmonary sodium and liquid absorption. Application of the H2S-liberating molecule Na2S (50 μM) to the alveolar compartment of rat lungs in situ decreased baseline liquid absorption and abrogated the stimulation of liquid absorption by the β-adrenergic agonist terbutaline. There was no additional effect of Na2S over that of the ENaC inhibitor amiloride. In electrophysiological Ussing chamber experiments with native lung epithelia (Xenopus laevis), Na2S inhibited the stimulation of amiloride-sensitive current by terbutaline. β-adrenergic agonists generally increase ENaC abundance by cAMP formation and activation of PKA. Activation of this pathway by forskolin and 3-isobutyl-1-methylxanthine increased amiloride-sensitive currents in H441 pulmonary epithelial cells. This effect was inhibited by Na2S in a dose-dependent manner (5-50 μM). Na2S had no effect on cellular ATP concentration, cAMP formation, and activation of PKA. By contrast, Na2S prevented the cAMP-induced increase in ENaC activity in the apical membrane of H441 cells. H441 cells expressed the H2S-generating enzymes cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase, and they produced H2S amounts within the employed concentration range. These data demonstrate that H2S prevents the stimulation of ENaC by cAMP/PKA and, thereby, inhibits the proabsorptive effect of β-adrenergic agonists on lung liquid clearance.

  20. Investigation of absorption and scattering characteristics of kiwifruit tissue using a single integrating sphere system.

    PubMed

    Fang, Zhen-Huan; Fu, Xia-Ping; He, Xue-Ming

    2016-06-01

    For a quantitative understanding of light interaction with fruit tissue, it is critical to obtain two fundamental parameters: the absorption coefficient and the scattering coefficient of the tissue. This study was to investigate the optical properties of kiwifruit tissue at the wavelength of 632.8 nm. The total reflectance and total transmittance of kiwifruit tissue from three parts (including the flesh part, the seed part, and the seed-base part) were measured using a single integrating sphere system. Based on the measured spectral signals, the absorption coefficient μa and the reduced scattering coefficient μs' of kiwifruit tissue were calculated using the inverse adding-doubling (IAD) method. Phantoms made from Intralipid 20% and India ink as well as a Biomimic solid phantom were used for system validation. The mean values of μa and μs' of different parts of the kiwifruit were 0.031-0.308 mm(-1) and 0.120-0.946 mm(-1), respectively. The results showed significant differences among the μa and μs' of the three parts of the kiwifruit. The results of this study confirmed the importance of studying the optical properties for a quantitative understanding of light interaction with fruit tissue. Further investigation of fruit optical properties will be extended to a broader spectral region and different kinds of fruits.

  1. Deuterium absorption and material phase characteristics of Zr[sub 2]Fe

    SciTech Connect

    Nobile, A.; Mosley, W.C.; Holder, J.S.; Brooks, K.N.

    1992-12-30

    Scanning electron microscope (SEM) images of polished surfaces, electron probe microanalysis, and X-ray powder diffractometry indicated the presence of a continuous Zr[sub 2]Fe phase with secondary phases of ZrFe[sub 2], Zr[sub 5]FeSn, [alpha]-Zr, and Zr[sub 6]Fe[sub 3]O. A statistically-designed experiment to determine the effects of temperature, time, and vacuum quality On activation of St 198 revealed that when activated at low temperature (350[degrees]C) deuterium absorption rate was slower when the vacuum quality was pwr (2.5 Pa vs. 3[times]10[sup [minus]4] Pa). However, at higher activation temperature (500[degrees]C), deuterium absorption rate was fast and was independent of vacuum quality. Deuterium pressure-composition-temperature (P-C-T) data are reported for St 198 in the temperature range 200--500[degrees]C. The P-C-T data over the full range of deuterium loading and at temperatures of 350[degrees]C and below is described by: K[sub 0e]-([Delta]H[sub [alpha

  2. Investigation of absorption and scattering characteristics of kiwifruit tissue using a single integrating sphere system*

    PubMed Central

    Fang, Zhen-huan; Fu, Xia-ping; He, Xue-ming

    2016-01-01

    For a quantitative understanding of light interaction with fruit tissue, it is critical to obtain two fundamental parameters: the absorption coefficient and the scattering coefficient of the tissue. This study was to investigate the optical properties of kiwifruit tissue at the wavelength of 632.8 nm. The total reflectance and total transmittance of kiwifruit tissue from three parts (including the flesh part, the seed part, and the seed-base part) were measured using a single integrating sphere system. Based on the measured spectral signals, the absorption coefficient μ a and the reduced scattering coefficient μ s' of kiwifruit tissue were calculated using the inverse adding-doubling (IAD) method. Phantoms made from Intralipid 20% and India ink as well as a Biomimic solid phantom were used for system validation. The mean values of μ a and μ s' of different parts of the kiwifruit were 0.031–0.308 mm−1 and 0.120–0.946 mm−1, respectively. The results showed significant differences among the μ a and μ s' of the three parts of the kiwifruit. The results of this study confirmed the importance of studying the optical properties for a quantitative understanding of light interaction with fruit tissue. Further investigation of fruit optical properties will be extended to a broader spectral region and different kinds of fruits. PMID:27256682

  3. Palm tree peroxidase-based biosensor with unique characteristics for hydrogen peroxide monitoring.

    PubMed

    Alpeeva, Inna S; Niculescu-Nistor, Mihaela; Leon, Jaime Castillo; Csöregi, Elisabeth; Sakharov, Ivan Yu

    2005-11-15

    Three amperometric enzyme electrodes have been constructed by adsorbing anionic royal palm tree peroxidase (RPTP), anionic sweet potato peroxidase (SPP), or cationic horseradish peroxidase (HRP-C) on spectroscopic graphite electrodes. The resulting H(2)O(2)-sensitive biosensors were characterized both in a flow injection system and in batch mode to evaluate their main bioelectrochemical parameters, such as pH dependency, I(max), K(M)(app), detection limit, linear range, operational and storage stability. The obtained results showed a distinctly different behavior for the plant peroxidase electrodes, demonstrating uniquely superior characteristics of the RPTP-based sensors. The broader linear range observed for the RPTP-based biosensor is explained by a high stability of this enzyme in presence of H(2)O(2). The higher storage and operational stability of RPTP-based biosensor as well as its capability to measure hydrogen peroxide under acidic conditions connect with an extremely high thermal and pH-stability of RPTP.

  4. State of Ni in catalysts for glycerol hydrogenation and methane steam reforming as studied by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Tkachenko, O. P.; Kustov, L. M.

    2013-06-01

    X-ray absorption spectroscopy is used to study 1% Ni/Al2O3, 5% Ni/Al2O3, and 5% Ni/TiO2 catalysts for glycerol and methane conversion. The effect of treatment in H2 under microwave irradiation on the reduction of part of the nickel to the metallic state in the titanium oxide-supported catalyst is demonstrated.

  5. Characteristics of Wood Sawdust and Chips as Energy Absorption Filling Mediums

    NASA Astrophysics Data System (ADS)

    Singace, Abduljalil Abdulla

    Wood sawdust and chips, as carpentry processes remains, are introduced as alternatives for filling mediums in energy mitigation systems. The natural, economical and environment friendly material, wood, is modeled and its interaction with the collapse of tubes, typical energy absorption elements, has been considered. Compression tests on wood sawdust were used to extract its mechanical properties and the results of which have been used in the validation of the analytical models. The collapse of PVC tubes, filled with wood sawdust of different grades and densifications, has been analyzed considering multi-lobe mode, concertina mode and mixed mode. In these models, the interaction of wood sawdust filler on the final mode of collapse of PVC tubes has been incorporated and the final values of the mean crushing load show favourable results.

  6. [Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

    PubMed

    Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

    2008-07-01

    A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

  7. Effect of hydrogen in an argon GTAW shielding gas: Arc characteristics and bead morphology

    SciTech Connect

    Onsoeien, M.; Olson, D.L.; Liu, S. . Center for Welding and Joining Research); Peters, R. )

    1995-01-01

    The influence of hydrogen additions to an argon shielding gas on the heat input and weld bead morphology was investigated using the gas tungsten arc welding process. Variations in weld bead size and shape with hydrogen additions were related to changes in the ability of the arc to generate heat and not to generate perturbations in the weld pool caused by Marangoni fluid flow.

  8. Reversible change of the electrical characteristics of a metal-nitride-oxide-semiconductor structure under the effect of hydrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Kuliev, B. B.

    1990-12-01

    The effect of hydrogen adsorption-desorption on the volt-farad characteristics of a gas-sensitive Pt-Si3N4-SiO2-Si MNOS structure was investigated experimentally. Transient processes in this structure under H2 adsorption and desorption were also studied. The results indicate that this structure is sensitive to the presence of hydrogen in the ambient atmosphere. Its electrical characteristics change strongly and reversibly during the hydrogen adsorption and desorption. It is concluded that this structure can be used as a hydrogen sensor.

  9. Investigation of the 2-0 pressure-induced vibrational absorption spectrum of hydrogen at temperatures below ambient

    NASA Technical Reports Server (NTRS)

    Silvaggio, P. M.; Goorvitch, D.; Boese, R. W.

    1981-01-01

    A theoretical fit has been made to our laboratory measurements of the 2-0 collisionally induced H2 absorption band for temperatures of 122 and 273.3 K and at a density of 20 amagats. A Lennard-Jones 6-12 intermolecular potential and a Birnbaum-Cohen line profile have been used. The fit resulted in a chi-square of 0.2%. Line widths have also been derived as a function of temperature. The lifetimes of the states have been calculated.

  10. Investigation of the 1-0 pressure-induced vibrational absorption spectrum of hydrogen at temperatures below ambient

    NASA Technical Reports Server (NTRS)

    Goorvitch, D.; Silvaggio, P. M.; Boese, R. W.

    1981-01-01

    A theoretical fit has been made to laboratory measurements of the 1-0 collisionally induced H2 absorption band over a temperature range of 100-273 K and for densities up to 22 amagats. Both the Birnbaum-Cohen and the MacTaggert-Hunt line shape profiles were used. In addition, an intermolecular potential of either a Lennard-Jones 6-12 or a Morse-spline-van der Waals has been used for each line shape. The best fit resulted in a chi-square of 5%. Line widths have also been derived as a function of temperature. The lifetimes of the states were calculated.

  11. Metal Particle Growth During Glucose Hydrogenation over Ru/SiO2 Evaluated by X-ray Absorption Spectroscopy and Electron Microscopy

    SciTech Connect

    Maris,E.; Ketchie, W.; Oleshko, V.; Davis, R.

    2006-01-01

    Biorenewable resources such as carbohydrates are considered alternative feedstocks for oxygenated chemicals. This work investigates the stability of silica-supported Ru catalysts in the aqueous phase conversion of glucose to sorbitol. In situ X-ray absorption spectroscopy at the Ru K edge revealed that air-exposed silica-supported Ru was in an oxidized state but was subsequently reduced in aqueous solutions saturated with 40 bar H{sub 2} at 373 K. Furthermore, exposure to aqueous phase conditions resulted in the sintering of Ru particles on the silica surface. However, the presence of glucose in the aqueous phase stabilized the growth of the Ru particles. Batchwise hydrogenation of glucose at 373 K and 80 bar H{sub 2} over a Ru/SiO{sub 2} (2.67 wt %) catalyst is nearly 100% selective to sugar alcohol with an average turnover frequency of 0.21 {+-} 0.04 s{sup -1}. The hydrogenation reaction was not mass transfer limited according to the Madon-Boudart criterion.

  12. Characteristics of Organobentonite and Study of Iodide Adsorption on Organobentonite using X-ray Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Ha, J.; Hwang, B.; Hwang, J.; Brown, G. E.

    2008-12-01

    The adsorption of iodide on untreated bentonite and bentonites modified with organic cation (i.e., hexadecylpyridinium chloride monohydrate (HDP+)) was investigated, and the organobentonites were characterized using uptake measurements, micro X-ray diffraction (micro-XRD), and electrophoretic mobility measurements prior to reaction with KI solutions. Uptake measurements indicate that bentonite has a high affinity for HDP+. Increasing [HDP+](aq) results in an increase in HDP+ uptake on bentonite by up to 280% of the CEC equivalents of bentonite, and causes a concomitant increase in Na released as a result of the replacement of exchangeable inorganic cations in bentonite interlayers. Based micro-XRD, the d001 spacing of untreated bentonite was 1.22 nm whereas organobentonites modified with HDP+ at different equivalent amounts, corresponding to 100%, 200%, and 400% of the cation exchange capacity (CEC) of bentonite, showed d001 spacings of 1.96 nm, 3.77 nm, and 3.77 nm, respectively. Our micro-XRD study indicates that organobentonites significantly expanded in basal spacing and organic cations were substantially intercalated into the interlayer spaces of montmorillonite. The electrophoretic mobility indicates that the untreated bentonite had a negative surface charge over the entire pH range examined (pH 2-12) whereas the organobentonite at an equivalent amount corresponding to 200% of the CEC had a positive surface charge over this pH range. We found significant differences in adsorption capacities of iodide depending on the bentonite properties as follows: iodide adsorption capacities were 439 mmol/kg for the bentonite modified with HDP+ at an equivalent amount corresponding to 200% of the CEC of bentonite whereas no adsorption of iodide was observed for the untreated bentonite. The molecular environments of iodine adsorbed on organobentonites were further studied using I K-edge and LIII-edge x-ray absorption spectroscopy (XAS). The X-ray absorption near

  13. Deuterium absorption and material phase characteristics of Zr{sub 2}Fe

    SciTech Connect

    Nobile, A.; Mosley, W.C.; Holder, J.S.; Brooks, K.N.

    1992-12-30

    Scanning electron microscope (SEM) images of polished surfaces, electron probe microanalysis, and X-ray powder diffractometry indicated the presence of a continuous Zr{sub 2}Fe phase with secondary phases of ZrFe{sub 2}, Zr{sub 5}FeSn, {alpha}-Zr, and Zr{sub 6}Fe{sub 3}O. A statistically-designed experiment to determine the effects of temperature, time, and vacuum quality On activation of St 198 revealed that when activated at low temperature (350{degrees}C) deuterium absorption rate was slower when the vacuum quality was pwr (2.5 Pa vs. 3{times}10{sup {minus}4} Pa). However, at higher activation temperature (500{degrees}C), deuterium absorption rate was fast and was independent of vacuum quality. Deuterium pressure-composition-temperature (P-C-T) data are reported for St 198 in the temperature range 200--500{degrees}C. The P-C-T data over the full range of deuterium loading and at temperatures of 350{degrees}C and below is described by: K{sub 0e}-({Delta}H{sub {alpha}}/RT)=PD{sub 2}q{sup 2}/(q*{minus}q){sup 2} where {Delta}H{alpha} and K{sub 0} have values of 101.8 kJ{center_dot}mole{sup {minus}1} and 3.24{times}10{sup {minus}8}Pa{sup {minus}1}, and q* is 15.998 kPa{center_dot}L{sup {minus}1}{center_dot}g{sup {minus}1}. At higher temperatures, one or more secondary reactions in the solid phase occur that slowly consume D{sub 2} from the gas phase. XRD suggests these reactions to be: 2 Zr{sub 2}FeD{sub x} {yields} x ZrD{sub 2} + x/3 ZrFe{sub 2} + (2 {minus} 2/3x) Zr{sub 2}Fe and Zr{sub 2}FeD{sub x} + (2 {minus}1/2x) D{sub 2} {yields} ZrD{sub 2} + Fe, where 0 < x < 3. Reaction between gas phase deuterium and Zr2FC formed in the first reaction accounts for the observed consumption of deuterium from the gas phase by this reaction.

  14. Temporal and spatial temperature distributions in transversely heated graphite tube atomizers and their analytical characteristics for atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Sperling, Michael; Welz, Bernard; Hertzberg, Joachim; Rieck, Christof; Marowsky, Gerd

    1996-07-01

    The important role which temperature plays in atomic absorption spectrometry (AAS) for the formation and detection of atoms in the absorption volume is discussed and the literature is reviewed. Non-homogeneous temperature distribution in the absorption volume is in contradiction to one of the prerequisites for the application of Beer's law used in AAS to convert absorbance into analyte concentration or mass, and is particularly troublesome for an "absolute analysis" envisaged for electrothermal atomic absorption spectrometry (ETAAS). Coherent anti-Stokes Raman scattering (CARS) is used to study the gas-phase temperature distribution in a state-of-the-art transversely heated graphite tube atomizer (THGA). The effect of the internal gas flow on the size of the heated atmosphere is studied by steady-state temperature measurements. Temporally and spatially resolved measurements make it possible to study the temperature field within the atomizer volume in all three dimensions during the rapid heating of the furnace to final temperatures in the range 2173-2673 K. The role of the integrated platform of the THGA on the temperature field is investigated by temperature measurements of the gas phase in the presence and absence of the platform. The platform is identified as the major source of temperature gradients inside the tube volume, which may be as high as 1000 K in the radial direction during rapid heating. These gradients are most pronounced for heating cycles starting at room temperature and gradually decrease with increasing starting temperature. Shortly after the tube wall reaches its final temperature, the gas-phase temperature equilibrates and approaches the wall temperature. Because of the unavoidable contact with the cold environment at the open ends of the tube, minor temperature gradients are observed in the gas phase also in longitudinal direction, which can be further reduced by restricting the openings with end caps. The results obtained for the THGA are

  15. Enhanced Hydrogen Evolution in the Presence of Plasmonic Au-Photo-Sensitized g-C3N4 with an Extended Absorption Spectrum from 460 to 640 nm

    PubMed Central

    Xie, Lihong; Ai, Zhuyu; Zhang, Meng; Sun, Runze; Zhao, Weirong

    2016-01-01

    Extensively spectral-responsive photocatalytic hydrogen production was achieved over g-C3N4 photo-sensitized by Au nanoparticles. The photo-sensitization, which was achieved by a facile photo-assisted reduction route, resulted in an extended spectral range of absorption from 460 to 640 nm. The photo-sensitized g-C3N4 (Au/g-C3N4) photocatalysts exhibit significantly enhanced photocatalytic hydrogen evolution with a TOF value of 223 μmol g-1 h-1, which is a 130-fold improvement over g-C3N4. The hydrogen production result confirms that Au nanoparticles are effective photo-sensitizers for the visible light-responsive substrate g-C3N4. UV–vis diffuse reflection spectra (DRS), photoluminescence spectra (PL), electron spin resonance (ESR), and electrochemical measurements were used to investigate the transfer process of photogenerated electrons. The optimal Au/g-C3N4 photocatalyst displays the lowest charge transfer resistance of 18.45 Ω cm-2 and a high electron transfer efficiency, as determined by electrochemical impedance spectroscopy (EIS). The photo-sensitized g-C3N4 shows a broad range of response to visible light (400–640 nm), with significantly high incident photon-to-current efficiency (IPCE) values of 14.52%, 2.9%, and 0.74% under monochromatic light irradiation of 400, 550, and 640 nm, respectively. ESR characterization suggests that Au nanoparticles are able to absorb visible light of wavelengths higher than 460 nm and to generate hot electrons due to the SPR effect. PMID:27575246

  16. Enhanced Hydrogen Evolution in the Presence of Plasmonic Au-Photo-Sensitized g-C3N4 with an Extended Absorption Spectrum from 460 to 640 nm.

    PubMed

    Xie, Lihong; Ai, Zhuyu; Zhang, Meng; Sun, Runze; Zhao, Weirong

    2016-01-01

    Extensively spectral-responsive photocatalytic hydrogen production was achieved over g-C3N4 photo-sensitized by Au nanoparticles. The photo-sensitization, which was achieved by a facile photo-assisted reduction route, resulted in an extended spectral range of absorption from 460 to 640 nm. The photo-sensitized g-C3N4 (Au/g-C3N4) photocatalysts exhibit significantly enhanced photocatalytic hydrogen evolution with a TOF value of 223 μmol g-1 h-1, which is a 130-fold improvement over g-C3N4. The hydrogen production result confirms that Au nanoparticles are effective photo-sensitizers for the visible light-responsive substrate g-C3N4. UV-vis diffuse reflection spectra (DRS), photoluminescence spectra (PL), electron spin resonance (ESR), and electrochemical measurements were used to investigate the transfer process of photogenerated electrons. The optimal Au/g-C3N4 photocatalyst displays the lowest charge transfer resistance of 18.45 Ω cm-2 and a high electron transfer efficiency, as determined by electrochemical impedance spectroscopy (EIS). The photo-sensitized g-C3N4 shows a broad range of response to visible light (400-640 nm), with significantly high incident photon-to-current efficiency (IPCE) values of 14.52%, 2.9%, and 0.74% under monochromatic light irradiation of 400, 550, and 640 nm, respectively. ESR characterization suggests that Au nanoparticles are able to absorb visible light of wavelengths higher than 460 nm and to generate hot electrons due to the SPR effect.

  17. Probing electrons in TiO2 polaronic trap states by IR-absorption: Evidence for the existence of hydrogenic states

    PubMed Central

    Sezen, Hikmet; Buchholz, Maria; Nefedov, Alexei; Natzeck, Carsten; Heissler, Stefan; Di Valentin, Cristiana; Wöll, Christof

    2014-01-01

    An important step in oxide photochemistry, the loading of electrons into shallow trap states, was studied using infrared (IR) spectroscopy on both, rutile TiO2 powders and single-crystal, r-TiO2(110) oriented samples. After UV-irradiation or n-doping by exposure to H-atoms broad IR absorption lines are observed for the powders at around 940 cm−1. For the single crystal substrates, the IR absorption bands arising from an excitation of the trapped electrons into higher-lying final states show additional features not observed in previous work. On the basis of our new, high-resolution data and theoretical studies on the polaron binding energy in rutile we propose that the trap states correspond to polarons and are thus intrinsic in nature. We assign the final states probed by the IR-experiments to hydrogenic states within the polaron potential. Implications of these observations for photochemistry on oxides will be briefly discussed. PMID:24448350

  18. Constraint on a varying proton-to-electron mass ratio from molecular hydrogen absorption towards quasar SDSS J123714.60+064759.5

    NASA Astrophysics Data System (ADS)

    Daprà, M.; Bagdonaite, J.; Murphy, M. T.; Ubachs, W.

    2015-11-01

    Molecular hydrogen transitions in the sub-damped Lyman α absorber at redshift zabs ≃ 2.69, towards the background quasar SDSS J123714.60+064759.5, were analysed in order to search for a possible variation of the proton-to-electron mass ratio μ over a cosmological time-scale. The system is composed of three absorbing clouds where 137 H2 and HD absorption features were detected. The observations were taken with the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a signal-to-noise ratio of 32 per 2.5 km s-1 pixel, covering the wavelengths from 356.6 to 409.5 nm. A comprehensive fitting method was used to fit all the absorption features at once. Systematic effects of distortions to the wavelength calibrations were analysed in detail from measurements of asteroid and `solar twin' spectra, and were corrected for. The final constraint on the relative variation in μ between the absorber and the current laboratory value is Δμ/μ = (-5.4 ± 6.3stat ± 4.0syst) × 10-6, consistent with no variation over a look-back time of 11.4 Gyr.

  19. Infrared absorption and emission characteristics of interstellar PAHs. [Polycyclic Aromatic Hydrocarbon

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms and are responsible for the emission.

  20. Infrared absorption and emission characteristics of interstellar PAHs (Polycyclic Aromatic Hydrocarbon)

    SciTech Connect

    Allamandola, L.J.; Tielens, A.G.G.M.; Barker, J.R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3050, 1610, 1300, 1150, and 885 cm/sup -1/ (3.28, 6.2, 7.7, 8.7 and 11.3 microns) is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis. This hypothesis is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the ir and Raman properties are discussed. Interstellar ir band emission is due to relaxation from highly vibrationally excited PAHs which have been excited by ultraviolet photons. The excitation/emission process is described in general and the ir fluorescence from one PAH, chrysene, is traced in detail. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs containing between 20 and 30 carbon atoms are responsible for the emission. 43 refs., 11 figs.

  1. Molar absorptivity (ε) and spectral characteristics of cyanidin-based anthocyanins from red cabbage.

    PubMed

    Ahmadiani, Neda; Robbins, Rebecca J; Collins, Thomas M; Giusti, M Monica

    2016-04-15

    Red cabbage extract contains mono and di-acylated cyanidin (Cy) anthocyanins and is often used as food colorants. Our objectives were to determine the molar absorptivity (ε) of different red cabbage Cy-derivatives and to evaluate their spectral behaviors in acidified methanol (MeOH) and buffers pH 1-9. Major red cabbage anthocyanins were isolated using a semi-preparatory HPLC, dried and weighed. Pigments were dissolved in MeOH and diluted with either MeOH (0.1% HCl) or buffers to obtain final concentrations between 5×10(-5) and 1×10(-3) mol/L. Spectra were recorded and ε calculated using Lambert-Beer's law. The ε in acidified MeOH and buffer pH 1 ranged between ~16,000-30,000 and ~13,000-26,000 L/mol cm, respectively. Most pigments showed higher ε in pH 8 than pH 2, and lowest ε between pH 4 and 6. There were bathochromic shifts (81-105 nm) from pH 1 to 8 and hypsochromic shifts from pH 8 to 9 (2-19 nm). Anthocyanins molecular structures and the media were important variables which greatly influenced their ε and spectral behaviors.

  2. Infrared absorption and emission characteristics of interstellar PAHs. [Polycyclic Aromatic Hydrocarbon

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms and are responsible for the emission.

  3. Studies on some characteristics of hydrogen production by cell-free extracts of rumen anaerobic bacteria.

    PubMed

    Joyner, A E; Winter, W T; Godbout, D M

    1977-03-01

    Hydrogen production was studied in the following rumen anaerobes: Bacteroides clostridiiformis, Butyrivibrio fibrisolvens, Enbacterium limosum, Fusobacterium necrophorum, Megasphaera elsdenii, Ruminococcus albus, and Ruminococcus flavefaciens. Clostridium pasteurianum and Escherichia coli were included for comparative purposes. Hydrogen production from dithionite, dithionite-reduced methyl viologen, pyruvate, and formate was determined. All species tested produced hydrogen from dithionite-reduce methyl viologen, but only C. pasteurianum, B. clostridiiformis, E. limosum, and M. elsdenii produced hydrogen from dithionite. All species except E. coli produced hydrogen from pyruvate, but activity was low or absent in extracts of E. limosum, F. necrophorum, R. albus, and R. flavefaciens unless methyl viologen was added. Hydrogen was produced from formate only by E. coli, B. clostridiiformis, E. limosum, F. necrophorum, and R. flavefaciens. Extracts were subjected to ultracentrifugation in an effort to determine the solubility of hydrogenase. The hydrogenase of all species except E. coli appeared to be soluble, although variable amounts of hydrogenase activity were detected in the pellet. Treatment of extracts of the rumen microbial species with DEAE-cellulose resulted in loss ofhydrogen production from pyruvate. Activity was restored by the addition of methyl viologen. It is concluded that hydrogen production in these rumen microorganisms is similar to that in the saccharolytic clostridia.

  4. Hydrogen-induced improvements in electrical characteristics of a-IGZO thin-film transistors

    NASA Astrophysics Data System (ADS)

    Tsao, S. W.; Chang, T. C.; Huang, S. Y.; Chen, M. C.; Chen, S. C.; Tsai, C. T.; Kuo, Y. J.; Chen, Y. C.; Wu, W. C.

    2010-12-01

    This study investigates the effect of hydrogen incorporation on amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs). The threshold voltage ( Vth) and subthreshold swing ( SS) of hydrogen-incorporated a-IGZO TFTs were improved, and the threshold voltage shift (Δ Vth) in hysteresis loop was also suppressed from 4 V to 2 V. The physical property and chemical composition of a-IGZO films were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Experimental results show that the hydrogen-induced passivation of the interface trap states between active layer and dielectric is responsible for the improvement of SS and Vth.

  5. Light absorption characteristics of carbonaceous aerosols in two remote stations of the southern fringe of the Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Li, Chaoliu; Yan, Fangping; Kang, Shichang; Chen, Pengfei; Hu, Zhaofu; Gao, Shaopeng; Qu, Bin; Sillanpää, Mika

    2016-10-01

    Light absorption characteristics of carbonaceous aerosols are key considerations in climate forcing research. However, in situ measurement data are limited, especially on the Tibetan Plateau (TP) - the Third Pole of the world. In this study, the mass absorption cross section (MAC) of elemental carbon (EC) and water soluble organic carbon (WSOC) of total suspended particles at two high-altitude stations (Lulang station and Everest station) in the Tibetan Plateau (TP) were investigated. The mean MACEC values at 632 nm were 6.85 ± 1.39 m2 g-1 and 6.49 ± 2.81 m2 g-1 at these two stations, both of which showed little seasonal variations and were slightly higher than those of EC of uncoated particles, indicating that the enhancement of MACEC by factors such as coating with organic aerosols was not significant. The mean MACWSOC values at 365 nm were 0.84 ± 0.40 m2 g-1 and 1.18 ± 0.64 m2 g-1 at the two stations. Obvious seasonal variations of high and low MACWSOC values appeared in winter and summer, respectively, mainly reflecting photobleaching of light absorption components of WSOC caused by fluctuations in sunlight intensity. Therefore, this phenomenon might also exists in other remote areas of the world. The relative contributions of radiative forcing of WSOC to EC were 6.03 ± 3.62% and 11.41 ± 7.08% at these two stations, with a higher ratio in winter. As a result, both the contribution of WSOC to radiative forcing of carbonaceous aerosols and its seasonal variation need to be considered in radiative forcing related study.

  6. Dynamic optical absorption characteristics of blood after slow and fast heating.

    PubMed

    Jia, Hao; Chen, Bin; Li, Dong

    2017-04-01

    Laser treatment is the most effective therapy in dermatology for vascular skin disorders, such as port-wine stains (PWS). Changes in heat-induced absorbance in blood must be determined for accurate numerical simulation and implementation of multi-pulse laser therapy for treatment of PWS. Thermally induced absorbance changes in hemoglobin in blood were compared in vitro between slow water bath heating and fast heating irradiated by using sub-millisecond Nd:YAG laser. Blood composition at different temperatures was calculated by comparing blood absorption spectra with those of pure HbO2, Hb, and metHb at room temperature. Blood absorbance to heat energy were categorized into three stages distinguished by metHb and coagulation points, which are the validity and security thresholds of the optimized therapy, respectively. Rapid laser heating can distinctively enhance blood absorbance by photochemically induced strong instability compared with slow heating at a constant temperature. Slow heating facilitates metHb point at 70 °C and coagulation point at 75 °C as the temperature of the water bath increases. However, the temperature at which metHb or coagulation point shifts to higher than 10 °C when pulses and fluence in laser irradiation change. Laser fluence less than 20 J/cm(2) and more than 50 J/cm(2) is unsuitable for laser treatment because of its low probability to coagulate vascular hyperplasia and high probability to damage normal tissues adjacent to target lesions, respectively. Few bubbles formed after mediate fluence is beneficial to minimize adverse side-effects. Considering blood absorbance, temperature evolution, and bubble formation, we recommend 30-40 J/cm(2) and 2-4 Hz frequency as the optimal laser parameters in sub-millisecond Nd:YAG laser.

  7. Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Eversman, W.

    1986-01-01

    Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a 'Gutin' propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

  8. Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Eversman, W.

    1986-01-01

    Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a "Gutin" propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

  9. An organic dye-polymer (phenol red-poly (vinyl alcohol)) composite architecture towards tunable -optical and -saturable absorption characteristics

    SciTech Connect

    Sreedhar, Sreeja Muneera, C. I.; Illyaskutty, Navas; Sreedhanya, S.; Philip, Reji

    2016-05-21

    Herein, we demonstrate that blending an organic dye (guest/filler), with a vinyl polymer (host template), is an inexpensive and simple approach for the fabrication of multifunctional photonic materials which could display an enhancement in the desirable properties of the constituent materials and, at the same time provide novel synergistic properties for the guest-host system. A new guest-host nanocomposite system comprising Phenol Red dye and poly (vinyl alcohol) as guest and host template, respectively, which exhibits tunable optical characteristics and saturable absorption behavior, is introduced. The dependence of local electronic environment provided by the polymer template and the interactions of the polymer molecules with the encapsulated guest molecules on the observed optical/nonlinear absorption behavior is discussed. An understanding of the tunability of the optical/ photophysical processes, with respect to the filler content, as discussed herein could help in the design of improved optical materials for several photonic device applications like organic light emitting diodes and saturable absorbers.

  10. Ultrasonic absorption characteristics of porous carbon-carbon ceramics with random microstructure for passive hypersonic boundary layer transition control

    NASA Astrophysics Data System (ADS)

    Wagner, Alexander; Hannemann, Klaus; Kuhn, Markus

    2014-06-01

    Preceding studies in the high enthalpy shock tunnel Göttingen of the German Aerospace Center (DLR) revealed that carbon fibre reinforced carbon ceramic (C/C) surfaces can be utilized to damp hypersonic boundary layer instabilities leading to a delay of boundary layer transition onset. To assess the ultrasonic absorption properties of the material, a test rig was set up to measure the reflection coefficient at ambient pressures ranging from 0.1 × 105 to 1 × 105 Pa. For the first time, broadband ultrasonic sound transducers with resonance frequencies of up to 370 kHz were applied to directly cover the frequency range of interest with respect to the second-mode instabilities observed in previous experiments. The reflection of ultrasonic waves from three flat plate test samples with a porous layer thickness between 5 and 30 mm was investigated and compared to an ideally reflecting surface. C/C was found to absorb up to 19 % of the acoustic power transmitted towards the material. The absorption characteristics were investigated theoretically by means of the quasi-homogeneous absorber theory. The experimental results were found to be in good agreement with the theory.

  11. Characteristics of hydrogen ion transport in urinary bladder of water turtle.

    PubMed

    Steinmetz, P R

    1967-10-01

    The mechanism of acidification by the urinary bladder of the water turtle was studied in an in vitro system which permitted control and measurement of electrical and concentration driving forces. The rate of hydrogen ion secretion was measured by means of a pH stat technique in the absence of exogenous carbon dioxide and bicarbonate. Transport of hydrogen ion into the solution bathing the mucosal surface of the bladder was associated with the appearance of alkali in the serosal compartment. The mean rate of hydrogen ion secretion in the absence of electrical and concentration gradients across the bladder was 0.96 mumole/hr. The secretion rate was only slightly greater in the presence of the spontaneous potential difference. The maximal hydrogen ion gradient that could be generated by the bladder was 3.33 pH units in the presence of the spontaneous voltage and 3.02 pH units in the short-circuited state. Hydrogen ion secretion was markedly reduced by acetazolamide and anaerobiosis, which indicated that under our experimental conditions acidification depended on the production and enzymatic hydration of metabolic carbon dioxide. On the basis of the stoichiometry of the pH changes across the membrane under different conditions, it is suggested that the active transport mechanism for hydrogen ion is located near the mucosal surface of the epithelial cell and that the alkali generated in back of the pump moves passively into the serosal fluid along an electrochemical gradient.

  12. Correlation between Fe-Zn Interdiffusion Observed by Scanning Capacitance Microscopy and Device Characteristics of Electro-Absorption Modulators

    NASA Astrophysics Data System (ADS)

    Ogasawara, Matsuyuki; Iga, Ryuzo; Yamanaka, Takayuki; Kondo, Susumu; Kondo, Yasuhiro

    2003-04-01

    The advantages of scanning capacitance microscopy (SCM) in observing Fe-Zn interdiffusion of an electro-absorption (EA) modulator and the relationship between the interdiffusion and device characteristics are discussed. SCM images show that there is a Zn diffusion region, in which the semi-insulating region is converted into p-type due to Zn diffusion, on both sides of the mesa and the Zn diffusion region becomes smaller as the Fe doping concentration is reduced. By comparison, scanning electron microscopy (SEM) images captured after stain etching of EA modulators did not clearly delineate the Zn diffusion front. The influence of a ruthenium (Ru)-doped InP burying layer on the interdiffusion has also been investigated by SCM. These results indicate that in order to improve the performance of EA modulators, it is important to prevent Zn diffusion into the semi-insulating layers.

  13. Extended x-ray-absorption and electron-energy-loss fine-structure studies of the local atomic structure of amorphous unhydrogenated and hydrogenated silicon carbide

    NASA Astrophysics Data System (ADS)

    Kaloyeros, Alain E.; Rizk, Richard B.; Woodhouse, John B.

    1988-12-01

    Extended x-ray-absorption (EXAFS) and electron-energy-loss fine-structure (EXELFS) measurements have been performed on amorphous unhydrogenated silicon carbide, a-SiC, and amorphous hydrogenated silicon carbide, a-SiC:H. Two hydrogenated samples with hydrogen concentrations corresponding, respectively, to H flows of 4 sccm (20% of argon flow) and 8 sccm (40% of argon flow) during the reactive sputtering process, were analyzed (sccm denotes standard cubic centimeters per minute at STP). It is found that short-range order (SRO), consisting of the same tetrahedrally coordinated units present in cubic crystalline c-SiC (zinc-blende structure), where a Si atom is surrounded by nearly four C atoms and vice versa, does exist in all the amorphous samples. This SRO, however, is detected only at a level of the first C and Si coordination shells in a-SiC and a-SiC:H. The structural disorder of the first Si and C coordination shells in all forms of amorphous SiC is somewhat greater than c-SiC, and it decreases appreciably as hydrogen is added. The a-SiC sample exhibits large Si and C coordination numbers, almost identical to c-SiC, a low atomic density, and virtually the same Si-C bond length as c-SiC. These results indicate that a relatively small concentration of large voids exist in a highly disordered a-SiC matrix. The a-SiC:H samples, on the other hand, exhibit a decrease in the C coordination number relative to a-SiC, which is independent of H concentration, low Si and C atomic densities, comparable to a-SiC, and virtually the same Si coordination number as a-SiC. These EXAFS-EXELFS results are consistent with a model where part of the H is substituting for Si in the local tetrahedra surrounding C atoms, while the rest is located inside internal voids in the a-SiC:H samples. The surface of the voids is composed of C atoms which have at least one bond to H, and of Si atoms. Finally, a straightforward computational procedure is applied to estimate the size of these voids

  14. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    SciTech Connect

    Wagener, M. C.; Botha, J. R.; Carrington, P. J.; Krier, A.

    2014-07-28

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  15. Characteristics of hydrogen produced by partial oxidation and auto-thermal reforming in a small methanol reformer

    NASA Astrophysics Data System (ADS)

    Horng, Rong-Fang; Chou, Huann-Ming; Lee, Chiou-Hwang; Tsai, Hsien-Te

    This paper investigates experimentally, the transient characteristics of a small methanol reformer using partial oxidation (POX) and auto-thermal reforming (ATR) for fuel cell applications. The parameters varied were heating temperature, methanol supply rate, steady mode shifting temperature, O 2/C (O 2/CH 3OH) and S/C (H 2O/CH 3OH) molar ratios with the main aim of promoting a rapid response and a high flow rate of hydrogen. The experiments showed that a high steady mode shifting temperature resulted in a faster temperature rise at the catalyst outlet and vice versa and that a low steady mode shifting temperature resulted in a lower final hydrogen concentration. However, when the mode shifting temperature was too high, the hydrogen production response was not necessarily improved. It was subsequently shown that the optimum steady mode shifting temperature for this experimental set-up was approximately 75 °C. Further, the hydrogen concentration produced by the auto-thermal process was as high as 49.12% and the volume flow rate up to 23.0 L min -1 compared to 40.0% and 20.5 L min -1 produced by partial oxidation.

  16. Hydrogen environment embrittlement.

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1972-01-01

    Hydrogen embrittlement is classified into three types: internal reversible hydrogen embrittlement, hydrogen reaction embrittlement, and hydrogen environment embrittlement. Characteristics of and materials embrittled by these types of hydrogen embrittlement are discussed. Hydrogen environment embrittlement is reviewed in detail. Factors involved in standardizing test methods for detecting the occurrence of and evaluating the severity of hydrogen environment embrittlement are considered. The effects of test technique, hydrogen pressure, purity, strain rate, stress concentration factor, and test temperature are discussed.

  17. Adsorption and diffusion characteristics of lithium on hydrogenated α- and β-silicene

    PubMed Central

    Kandemir, Ali; Bacaksiz, Cihan

    2017-01-01

    Using first-principles density functional theory calculations, we investigate adsorption properties and the diffusion mechanism of a Li atom on hydrogenated single-layer α- and β-silicene on a Ag(111) surface. It is found that a Li atom binds strongly on the surfaces of both α- and β-silicene, and it forms an ionic bond through the transfer of charge from the adsorbed atom to the surface. The binding energies of a Li atom on these surfaces are very similar. However, the diffusion barrier of a Li atom on H-α-Si is much higher than that on H-β-Si. The energy surface calculations show that a Li atom does not prefer to bind in the vicinity of the hydrogenated upper-Si atoms. Strong interaction between Li atoms and hydrogenated silicene phases and low diffusion barriers show that α- and β-silicene are promising platforms for Li-storage applications. PMID:28904835

  18. Hydrogenated amorphous silicon oxide (a-SiOx:H) single junction solar cell with 8.8% initial efficiency by reducing parasitic absorptions

    NASA Astrophysics Data System (ADS)

    Kim, Do Yun; Guijt, Erwin; van Swaaij, René A. C. M. M.; Zeman, Miro

    2017-04-01

    Hydrogenated amorphous silicon oxide (a-SiOx:H) solar cells have been successfully implemented to multi-junction thin film silicon solar cells. The efficiency of these solar cells, however, has still been below that of state-of-the-art solar cells mainly due to the low Jsc of the a-SiOx:H solar cells and the unbalanced current matching between sub-cells. In this study, we carry out optical simulations to find the main optical losses for the a-SiOx:H solar cell, which so far was mainly optimized for Voc and fill-factor (FF). It is observed that a large portion of the incident light is absorbed parasitically by the p-a-SiOx:H and n-a-SiOx:H layers, although the use of these layers leads to the highest Voc × FF product. When a more transparent and conductive p-nc-SiOx:H layer is substituted for the p-a-SiOx:H layer, the parasitic absorption loss at short wavelengths is notably reduced, leading to higher Jsc. However, this gain in Jsc by the use of the p-nc-SiOx:H compromises the Voc. When replacing the n-a-SiOx:H layer for an n-nc-SiOx:H layer that has low n and k values, the plasmonic absorption loss at the n-nc-SiOx:H/Ag interfaces and the parasitic absorption in the n-nc-SiOx:H are substantially reduced. Implementation of this n-nc-SiOx:H leads to an increase of the Jsc without a drop of the Voc and FF. When implementing a thinner p-a-SiOx:H layer, a thicker i-a-SiOx:H layer, and an n-nc-SiOx:H layer, a-SiOx:H solar cells with not only high Jsc but also high Voc and FF can be fabricated. As a result, an 8.8% a-SiOx:H single junction solar cell is successfully fabricated with a Voc of 1.02 V, a FF of 0.70, and a Jsc of 12.3 mA/cm2, which is the highest efficiency ever reported for this type of solar cell.

  19. Tracking Co(I) Intermediate in operando in Photocatalytic Hydrogen Evolution by X-ray transient Absorption Spectroscopy and DFT Calculation

    SciTech Connect

    Li, Zhi-Jun; Zhan, Fei; Xiao, Hongyan; Zhang, Xiaoyi; Kong, Qing-Yu; Fan, Xiang-Bing; Liu, Wen-Qiang; Huang, Mao-Yong; Huang, Cheng; Gao, Yu-Ji; Li, Xu-Bing; Meng, Qing-Yuan; Feng, Ke; Chen, Bin; Tung, Chen-Ho; Zhao, Hai-Feng; Tao, Ye; Wu, Li-Zhu

    2016-12-07

    X-ray transient absorption spectroscopy (XTA) and optical transient spectroscopy (OTA) were used to probe the Co(I) intermediate generated in situ from an aqueous photocatalytic hydrogen evolution system, with [RuII(bpy)3]Cl2·6H2O as the photosensitizer, ascorbic acid/ascorbate as the electron donor, and the Co-polypyridyl complex ([CoII(DPABpy) Cl]Cl) as the pre-catalyst. Upon exposure to light, the XTA measured at Co K-edge visualizes the grow and decay of the Co(I) intermediate, and reveals its Co-N bond contraction of 0.09 ± 0.03 Å. Density functional theory (DFT) calculations support the bond contraction and illustrate that the metal-to-ligand π back-bonding greatly stabilizes the penta-coordinated Co(I) intermediate, which provides easy photon access. To the best of our knowledge, this is the first example of capturing the penta-coordinated Co(I) intermediate in operando with bond contraction by XTA, thereby providing new insights for fundamental understanding of structure– function relationship of cobalt-based molecular catalysts.

  20. A study of the parameters of traps in hydrogenated amorphous silicon by the method of volt-farad characteristics

    NASA Astrophysics Data System (ADS)

    Nevzorov, A. N.; Zarifiants, Iu. A.; Abramov, V. O.; Drozd, V. E.

    1983-08-01

    The localized states in hydrogenated amorphous silicon obtained by a high-frequency discharge in monosilane have been investigated by analyzing the low-frequency (1-10 Hz) volt-farad characteristics of a Schottky barrier in a-Si-H. The density of the states at zero shift determined by this method (1.5 x 10 to the 17th per cu cm eV) is in agreement with the results obtained by other methods. The effective cross-section of electron capture by traps is estimated at 10 to the -14th sq cm.

  1. LIGHT-WEIGHT NANOCRYSTALLINE HYDROGEN STORAGE MATERIALS

    SciTech Connect

    S. G. Sankar; B. Zande; R.T. Obermyer; S. Simizu

    2005-11-21

    During Phase I of this SBIR Program, Advanced Materials Corporation has addressed two key issues concerning hydrogen storage: 1. We have conducted preliminary studies on the effect of certain catalysts in modifying the hydrogen absorption characteristics of nanocrystalline magnesium. 2. We have also conducted proof-of-concept design and construction of a prototype instrument that would rapidly screen materials for hydrogen storage employing chemical combinatorial technique in combination with a Pressure-Composition Isotherm Measurement (PCI) instrument. 3. Preliminary results obtained in this study approach are described in this report.

  2. A mixed quantum-classical molecular dynamics study of anti-tetrol and syn-tetrol dissolved in liquid chloroform: hydrogen-bond structure and its signature on the infrared absorption spectrum.

    PubMed

    Kwac, Kijeong; Geva, Eitan

    2013-12-27

    The intramolecular hydrogen-bond structure of stereoselectively synthesized syn-tetrol and anti-tetrol dissolved in deuterated chloroform is investigated via a mixed quantum-classical molecular dynamics simulation. An extensive conformational analysis is performed in order to determine the dominant conformations, the distributions among them, and their sensitivity to the method for assigning partial charges (RESP vs AM1-BCC). The signature of the conformational distribution and method of assigning partial charges on the infrared absorption spectra is analyzed in detail. The relationship between the spectra and the underlying hydrogen-bond structure is elucidated.

  3. Hydrogen/deuterium exchange mass spectrometry applied to IL-23 interaction characteristics: potential impact for therapeutics.

    PubMed

    Iacob, Roxana E; Krystek, Stanley R; Huang, Richard Y-C; Wei, Hui; Tao, Li; Lin, Zheng; Morin, Paul E; Doyle, Michael L; Tymiak, Adrienne A; Engen, John R; Chen, Guodong

    2015-04-01

    IL-23 is an important therapeutic target for the treatment of inflammatory diseases. Adnectins are targeted protein therapeutics that are derived from domain III of human fibronectin and have a similar protein scaffold to antibodies. Adnectin 2 was found to bind to IL-23 and compete with the IL-23/IL-23R interaction, posing a potential protein therapeutic. Hydrogen/deuterium exchange mass spectrometry and computational methods were applied to probe the binding interactions between IL-23 and Adnectin 2 and to determine the correlation between the two orthogonal methods. This review summarizes the current structural knowledge about IL-23 and focuses on the applicability of hydrogen/deuterium exchange mass spectrometry to investigate the higher order structure of proteins, which plays an important role in the discovery of new and improved biotherapeutics.

  4. A Few Facts about Hydrogen [and] Hydrogen Bibliography.

    ERIC Educational Resources Information Center

    Hinds, H. Roger

    Divided into two sections, this publication presents facts about and the characteristics of hydrogen and a bibliography on hydrogen. The first section lists nine facts on what hydrogen is, four on where hydrogen is found, nine on how hydrogen is used, nine on how hydrogen can be used, and 14 on how hydrogen is made. Also included are nine…

  5. Hydrogen induced fracture characteristics of single crystal nickel-based superalloys

    NASA Technical Reports Server (NTRS)

    Chen, Po-Shou; Wilcox, Roy C.

    1990-01-01

    A stereoscopic method for use with x ray energy dispersive spectroscopy of rough surfaces was adapted and applied to the fracture surfaces single crystals of PWA 1480E to permit rapid orientation determinations of small cleavage planes. The method uses a mathematical treatment of stereo pair photomicrographs to measure the angle between the electron beam and the surface normal. One reference crystal orientation corresponding to the electron beam direction (crystal growth direction) is required to perform this trace analysis. The microstructure of PWA 1480E was characterized before fracture analysis was performed. The fracture behavior of single crystals of the PWA 1480E nickel-based superalloy was studied. The hydrogen-induced fracture behavior of single crystals of the PWA 1480E nickel-based superalloy was also studied. In order to understand the temperature dependence of hydrogen-induced embrittlement, notched single crystals with three different crystal growth orientations near zone axes (100), (110), and (111) were tensile tested at 871 C (1600 F) in both helium and hydrogen atmospheres at 34 MPa. Results and conclusions are given.

  6. Effect of surface characteristics of wood-based activated carbons on adsorption of hydrogen sulfide

    SciTech Connect

    Adib, F.; Bagreev, A.; Bandosz, T.J.

    1999-06-15

    Three wood-based commercial activated carbons supplied by Westvaco were studied as adsorbents of hydrogen sulfide. The initial materials were characterized using sorption of nitrogen, Boehm titration, potentiometric titration, water sorption, thermal analysis, and temperature-programmed desorption. The breakthrough tests were done at low concentrations of H{sub 2}S in the input gas to simulate conditions in water pollution control plants where carbon beds are used as odor adsorbents. In spite of apparent general similarities in the origin of the materials, method of activation, surface chemistry, and porosity, significant differences in their performance as hydrogen sulfide adsorbents were observed. Results show that the combined effect of the presence of pores large enough to accommodate surface functional groups and small enough to have the film of water at relatively low pressure contributes to oxidation of hydrogen sulfide. Moreover, there are features of activated carbon surfaces such as local environment of acidic/basic groups along with the presence of alkali metals which are important to the oxidation process.

  7. [Study on the characteristic UV absorption parameters of dissolved organic matter extracted from chicken manure during composting].

    PubMed

    Li, Ming-xiao; He, Xiao-song; Liu, Jun; Xi, Bei-dou; Zhao, Yue; Wei, Zi-min; Jiang, Yong-hai; Su, Jing; Hu, Chun-ming

    2010-11-01

    The characteristic parameters obtained from UV-Visible spectra of dissolved organic matter (DOM) during composting were studied in the present paper. The results showed that, during composting progress, the non-humic substances were translated into humus substances, and the aromatization, humification degree and molecular weight of the humus substances increased, while the fatty chains linked with the benzene ring structure were cleavaged into carbonyl, carboxyl and other functional groups. The correlation analysis showed that, when DOM concentration (DOC) from all samples was the same, the specific ultraviolet absorbance values at 254 and 280 nm (SUVA254 and SUVA280, respectively), and the area of a spectrum obtained from 226 to 400 nm (A(226-400)) showed significant positive correlation, furthermore, they were all significantly negatively correlated with the concentration of DOM (DOC), but the correlation between A(226-400) and DOC was the best; The ratio between the absorbance value at 253 nm and that at 203 nm (E253/E203) was significantly correlative with SUVA254, SUVA280 and A 226-400, though the correlation between E253/E203 and DOC was not as good as the other three characteristic parameters; The ratio between the absorbance value at 250 nm and that at 365 nm (E250/E365) and the ratio between the absorbance value at 465 nm and that at 665 nm(E250/E365) were not correlated with the other parameters. The results showed that, the stability of DOM extracted from chicken manure increased during composting, and the complex ability between DOM and heavy metals enhanced as well; A(226-400) reflects the changes of compost maturity best in all UV-Visible spectral absorption parameters studied in this paper.

  8. Spatial structures based on color centers created by electrons in lithium fluoride crystals: Absorption and luminescence characteristics

    NASA Astrophysics Data System (ADS)

    Voitovich, A. P.; Kalinov, V. S.; Loiko, Yu. V.; Naumenko, N. N.; Runets, L. P.; Stupak, A. P.

    2008-01-01

    We have shown that in spatial structures based on color centers created by electrons in a lithium fluoride crystal, the distances between centers reach 1.6 nm and 3.6 nm for F1 and F2 centers respectively. This suggests considerable potential opportunities for using electron technology to form structures in the crystals with spatial resolution of such an order of magnitude. We measured the decrease in fluorine content on the irradiated surface of the crystal. We found the concentrations of F1, F2, F{3/+}, F3(R2), and F4(N1) centers. We established that the specific characteristics of color center formation by electrons leads to an increase in the efficiency of creation of F3 and F4 centers. We determined the decrease in the average luminescence lifetimes of F2 and F{3/+} centers as a result of concentration quenching. We observed distortion of the luminescence contour for F2 centers as a result of absorption of its short-wavelength portion by other centers and emission of radiation by the latter in its long-wavelength portion.

  9. Evaluation of metal ion absorptive characteristics of three types of plastic sample bags used for pecipitation sampling

    USGS Publications Warehouse

    Good, A.B.; Schroder, L.J.

    1984-01-01

    Simulated precipitation samples containing 16 metal ions were prepared at 4 pH values. Absorptive characteristics of polypropylene, polyethylene, and polyester/polyolefin sacks were evaluated at pH 3.5, 4.0, 4.5, and 5.0. Simulated precipitation was in contact with the sacks for 17 days, and subsamples were removed for chemical analysis at 3, 7, 10, 14, and 17 days after initial contact. All three types of plastic sacks absorbed Fe throughout the entire pH range. Polypropylene and polyethylene absorbed Pb throughout the entire pH range; polyester/polyolefin sacks absorbed Pb at pH 4.0 or greater. All plastic sacks also absorbed Cu, Mo, and V at pH 4.5 and 5.0. Leaching the plastic sacks with 0.7 percent HNO3 did not result in 100 percent of Cu, Fe, Pb, and V. These sacks would be suitable collection vessels for Ba, Be, Ca, Cd, Co, Li, Mg, Mn, Na Sr and Zn in precipitation through the pH range of 3.5 to 5.0.

  10. Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

    USDA-ARS?s Scientific Manuscript database

    The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

  11. Hydrogen environment embrittlement

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1972-01-01

    Hydrogen embrittlement is classified into three types: internal reversible hydrogen embrittlement, hydrogen reaction embrittlement, and hydrogen environment embrittlement. Characteristics of and materials embrittled by these types of hydrogen embrittlement are discussed. Hydrogen environment embrittlement is reviewed in detail. Factors involved in standardizing test methods for detecting the occurrence of and evaluating the severity of hydrogen environment embrittlement are considered. The effect of test technique, hydrogen pressure, purity, strain rate, stress concentration factor, and test temperature are discussed. Additional research is required to determine whether hydrogen environment embrittlement and internal reversible hydrogen embrittlement are similar or distinct types of embrittlement.

  12. Hydrogen evolution at a Pt-modified InP photoelectrode: Improvement of current-voltage characteristics by HCl etching

    SciTech Connect

    Kobayashi, Hikaru; Mizuno, Fumiaki; Nakato, Yoshihiro; Tsubomura, Hiroshi )

    1991-01-24

    Hydrogen photoevolution at p-InP electrodes coated with platinum and palladium has been studied. Efficient and stable solar to chemical energy conversion has been achieved after etching the electrodes with concentrated HCl. The current-voltage (I-V) behavior of the as-prepared electrode covered with a continuous Pt layer is poor, due probably to the presence of defect states in InP. The photocurrent density of this electrode decreases with time under illumination, presumably due to an increase in the defect density. After etching of the electrode with concentrated HCl, the barrier height is increased to 1.0 V, and the I-V characteristics are improved remarkably, showing no degradation under illumination. SEM, XPS, and AES analyses show that the concentrated HCl solution dissolves the InP substrate in the InP/Pt interfacial region, and simultaneously part of the Pt is removed from the InP surface. The I-V characteristics of the Pt-deposited electrodes are unaffected by hydrogen or nitrogen bubbling and the reason is discussed.

  13. Hydrogenation and dehydrogenation of interstellar PAHs: Spectral characteristics and H2 formation

    NASA Astrophysics Data System (ADS)

    Andrews, H.; Candian, A.; Tielens, A. G. G. M.

    2016-10-01

    Context. We have modelled the abundance distribution and IR emission of the first 3 members of the coronene family in the north-west photodissociation region of the well-studied reflection nebulae NGC 7023. Aims: Our aim was 3-fold: i) analyze the distribution of abundances; (ii) examine the spectral footprints from the hydrogenation state of polycyclic aromatic hydrocarbons (PAHs); and (iii) assess the role of PAHs in the formation of H2 in photodissociation regions. Methods: To model the physical conditions inside the cloud, we used the Meudon PDR Code, and we gave this as input to our kinetic model. We used specific molecular properties for each PAH, based on the latest data available at the present time. We considered the loss of an H atom or an H2 molecule as multiphoton processes, and we worked under the premise that PAHs with extra H atoms can form H2 through an Eley-Rideal abstraction mechanism. Results: In terms of abundances, we can distinguish clear differences with PAH size. The smallest PAH, coronene (C24H12), is found to be easily destroyed down to the complete loss of all of its H atoms. The largest species circumcircumcoronene (C96H24), is found in its normal hydrogenated state. The intermediate size molecule, circumcoronene (C54H18), shows an intermediate behaviour with respect to the other two, where partial dehydrogenation is observed inside the cloud. Regarding spectral variations, we find that the emission spectra in NGC 7023 are dominated by the variation in the ionization of the dominant hydrogenation state of each species at each point inside the cloud. It is difficult to "catch" the effect of dehydrogenation in the emitted PAH spectra since, for any conditions, only PAHs within a narrow size range will be susceptible to dehydrogenation, being quickly stripped off of all H atoms (and may isomerize to cages or fullerenes). The 3 μm region is the most sensitive one towards the hydrogenation level of PAHs. Conclusions: Based on our results, we

  14. A comprehensive investigation of structural, morphological, hydrogen absorption and magnetic properties of MmNi4.22Co0.48Mn0.15Al0.15 alloy

    NASA Astrophysics Data System (ADS)

    Zareii, Seyyed Mojtaba; Arabi, Hadi; Pourarian, Faiz

    2014-05-01

    A comprehensive study of structural, morphological, hydrogen absorption and magnetic properties of MmNi4.22 Co0.48Mn0.15Al0.15 alloy as a promising hydrogen storage media was investigated. The X-ray diffraction (XRD) profiles show that the alloy maintains its crystal structure (hexagonal LaNi5-type) even after 30 hydrogenation/dehydrogenation (H/D) cycles. However, the XRD peaks are found to be slightly broadened after cycling. SEM images reveal that particles size of the cycled sample decreases, with more uniform particle size distribution compared to noncycled ones. The pressure-composition (PC) isotherms and kinetics curves of hydrogen absorption reaction were obtained at different working temperatures by using a homemade Sievert apparatus. The enthalpy and entropy of hydride formation of the alloy were evaluated. Furthermore, the Jander diffusion and Johnson-Mehl-Avrami models as the fitting models were employed to study the kinetic mechanism of hydriding reaction and its activation energy. The room temperature magnetic measurements indicate that the milling and H/D cycling change the magnetic properties of the as-annealed alloy.

  15. Concentration, sources and light absorption characteristics of dissolved organic carbon on a medium-sized valley glacier, northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yan, Fangping; Kang, Shichang; Li, Chaoliu; Zhang, Yulan; Qin, Xiang; Li, Yang; Zhang, Xiaopeng; Hu, Zhaofu; Chen, Pengfei; Li, Xiaofei; Qu, Bin; Sillanpää, Mika

    2016-11-01

    Light-absorbing dissolved organic carbon (DOC) constitutes a major part of the organic carbon in glacierized regions, and has important influences on the carbon cycle and radiative forcing of glaciers. However, few DOC data are currently available from the glacierized regions of the Tibetan Plateau (TP). In this study, DOC characteristics of a medium-sized valley glacier (Laohugou Glacier No. 12, LHG) on the northern TP were investigated. Generally, DOC concentrations on LHG were comparable to those in other regions around the world. DOC concentrations in snow pits, surface snow and surface ice (superimposed ice) were 332 ± 132, 229 ± 104 and 426 ± 270 µg L-1, respectively. The average discharge-weighted DOC of proglacial stream water was 238 ± 96 µg L-1, and the annual DOC flux released from this glacier was estimated to be 6949 kg C yr-1, of which 46.2 % of DOC was bioavailable and could be decomposed into CO2 within 1 month of its release. The mass absorption cross section (MAC) of DOC at 365 nm was 1.4 ± 0.4 m2 g-1 in snow and 1.3 ± 0.7 m2 g-1 in ice, similar to the values for dust transported from adjacent deserts. Moreover, there was a significant relationship between DOC and Ca2+; therefore, mineral dust transported from adjacent arid regions likely made important contributions to DOC of the glacierized regions, although contributions from autochthonous carbon and autochthonous/heterotrophic microbial activity cannot be ruled out. The radiative forcing of snow pit DOC was calculated to be 0.43 W m-2, demonstrating that DOC in snow needs to be taken into consideration in accelerating melt of glaciers on the TP.

  16. Model calculation of the characteristic mass for convective and diffusive vapor transport in graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Bencs, László; Laczai, Nikoletta; Ajtony, Zsolt

    2015-07-01

    A combination of former convective-diffusive vapor-transport models is described to extend the calculation scheme for sensitivity (characteristic mass - m0) in graphite furnace atomic absorption spectrometry (GFAAS). This approach encompasses the influence of forced convection of the internal furnace gas (mini-flow) combined with concentration diffusion of the analyte atoms on the residence time in a spatially isothermal furnace, i.e., the standard design of the transversely heated graphite atomizer (THGA). A couple of relationships for the diffusional and convectional residence times were studied and compared, including in factors accounting for the effects of the sample/platform dimension and the dosing hole. These model approaches were subsequently applied for the particular cases of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn analytes. For the verification of the accuracy of the calculations, the experimental m0 values were determined with the application of a standard THGA furnace, operating either under stopped, or mini-flow (50 cm3 min- 1) of the internal sheath gas during atomization. The theoretical and experimental ratios of m0(mini-flow)-to-m0(stop-flow) were closely similar for each study analyte. Likewise, the calculated m0 data gave a fairly good agreement with the corresponding experimental m0 values for stopped and mini-flow conditions, i.e., it ranged between 0.62 and 1.8 with an average of 1.05 ± 0.27. This indicates the usability of the current model calculations for checking the operation of a given GFAAS instrument and the applied methodology.

  17. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  18. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  19. Hydrogen/Deuterium Exchange Mass Spectrometry Applied to IL-23 Interaction Characteristics: Potential Impact for Therapeutics

    PubMed Central

    Iacob, Roxana E.; Krystek, Stanley R.; Huang, Richard Y.-C.; Wei, Hui; Tao, Li; Lin, Zheng; Morin, Paul E.; Doyle, Michael L.; Tymiak, Adrienne A.; Engen, John R.

    2015-01-01

    Interleukin-23 (IL-23) is an important therapeutic target for the treatment of inflammatory diseases. Adnectins are targeted protein therapeutics that are derived from domain III of human fibronectin, and have similar protein scaffold to antibodies. A specific adnectin (Adnectin 2) was identified to bind to IL-23 and compete with IL-23/IL-23R interaction, being a potential protein therapeutic. Hydrogen/deuterium exchange mass spectrometry (HDX MS) and computational methods were applied to probe the binding interactions between IL-23 and Adnectin2 and to determine the correlation between the two orthogonal methods. This review article summarizes the current structural knowledge about Il-23 and it focuses on the applicability of HDX MS to investigate the higher order structure of proteins, which plays an important role for the discovery of new and improved biotherapeutics. PMID:25711416

  20. Extreme changes in stable hydrogen isotopes and precipitation characteristics in a landfalling Pacific storm

    USGS Publications Warehouse

    Coplen, T.B.; Neiman, P.J.; White, A.B.; Landwehr, J.M.; Ralph, F.M.; Dettinger, M.D.

    2008-01-01

    With a new automated precipitation collector we measured a remarkable decrease of 51??? in the hydrogen isotope ratio (?? 2H) of precipitation over a 60-minute period during the landfall of an extratropical cyclone along the California coast on 21 March 2005. The rapid drop in ??2H occurred as precipitation generation transitioned from a shallow to a much deeper cloud layer, in accord with synoptic-scale ascent and deep "seeder-feeder" precipitation. Such unexpected ?? 2H variations can substantially impact widely used isotope-hydrograph methods. From extreme ??2H values of -26 and -78???, we calculate precipitation temperatures of 9.7 and -4.2??C using an adiabatic condensation isotope model, in good agreement with temperatures estimated from surface observations and radar data. This model indicates that 60 percent of the moisture was precipitated during ascent as temperature decreased from 15??C at the ocean surface to -4??C above the measurement site.

  1. Characteristics of the molecular electron density, delocalization effect and hydrogen bonding interaction of nitroxoline

    NASA Astrophysics Data System (ADS)

    Arun Sasi, B. S.; Twinkle, A. R.; James, C.

    2017-08-01

    The density functional theoretical (DFT) calculations have been carried out at the B3LYP/6-311G(d,p) level of theory for nitroxoline monomer and dimer molecule. The dimer molecule formed between two nitroxoline subunits has the largest stability, and is held together by two Osbnd H⋯N hydrogen bonds. Stability of the molecule arising from hyperconjugative interaction and intra/inter molecular charge transfer has been analyzed using natural bond orbital (NBO) analysis. The topological analysis of electron localization function (ELF) provides effect of delocalization. Quantum theory of atoms in molecule (QTAIM) has been applied to gain deep understanding to the existence of intra- and inter-molecular interaction.

  2. Characteristics of transverse hydrogen jet in presence of multi air jets within scramjet combustor

    NASA Astrophysics Data System (ADS)

    Barzegar Gerdroodbary, M.; Fallah, Keivan; Pourmirzaagha, H.

    2017-03-01

    In this article, three-dimensional simulation is performed to investigate the effects of micro air jets on mixing performances of cascaded hydrogen jets within a scramjet combustor. In order to compare the efficiency of this technique, constant total fuel rate is injected through one, four, eight and sixteen arrays of portholes in a Mach 4.0 crossflow with a fuel global equivalence ratio of 0.5. In this method, micro air jets are released within fuel portholes to augment the penetration in upward direction. Extensive studies were performed by using the Reynolds-averaged Navier-Stokes equations with Menter's Shear Stress Transport (SST) turbulence model. Numerical studies on various air and fuel arrangements are done and the mixing rate and penetration are comprehensively investigated. Also, the flow feature of the fuel and air jets for different configuration is revealed. According to the obtained results, the influence of the micro air jets is significant and the presence of micro air jets increases the mixing rate about 116%, 77%, 56% and 41% for single, 4, 8 and 16 multi fuel jets, respectively. The maximum mixing rate of the hydrogen jet is obtained when the air jets are injected within the sixteen multi fuel jets. According to the circulation analysis of the flow for different air and fuel arrangements, it was found that the effects of air jets on flow structure are varied in various conditions and the presence of the micro jet highly intensifies the circulation in the case of 8 and 16 multi fuel jets.

  3. Hydrogen Embrittlement

    NASA Technical Reports Server (NTRS)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    Hydrogen embrittlement (HE) is a process resulting in a decrease in the fracture toughness or ductility of a metal due to the presence of atomic hydrogen. In addition to pure hydrogen gas as a direct source for the absorption of atomic hydrogen, the damaging effect can manifest itself from other hydrogen-containing gas species such as hydrogen sulfide (H2S), hydrogen chloride (HCl), and hydrogen bromide (HBr) environments. It has been known that H2S environment may result in a much more severe condition of embrittlement than pure hydrogen gas (H2) for certain types of alloys at similar conditions of stress and gas pressure. The reduction of fracture loads can occur at levels well below the yield strength of the material. Hydrogen embrittlement is usually manifest in terms of singular sharp cracks, in contrast to the extensive branching observed for stress corrosion cracking. The initial crack openings and the local deformation associated with crack propagation may be so small that they are difficult to detect except in special nondestructive examinations. Cracks due to HE can grow rapidly with little macroscopic evidence of mechanical deformation in materials that are normally quite ductile. This Technical Memorandum presents a comprehensive review of experimental data for the effects of gaseous Hydrogen Environment Embrittlement (HEE) for several types of metallic materials. Common material screening methods are used to rate the hydrogen degradation of mechanical properties that occur while the material is under an applied stress and exposed to gaseous hydrogen as compared to air or helium, under slow strain rates (SSR) testing. Due to the simplicity and accelerated nature of these tests, the results expressed in terms of HEE index are not intended to necessarily represent true hydrogen service environment for long-term exposure, but rather to provide a practical approach for material screening, which is a useful concept to qualitatively evaluate the severity of

  4. Potential mesogens based on pyridine derivatives: The geometric structure, conformational properties and characteristics of intermolecular hydrogen bonds

    NASA Astrophysics Data System (ADS)

    Fedorov, Mikhail S.; Giricheva, Nina I.; Shpilevaya, Kseniya E.; Lapykina, Elena A.; Syrbu, Svetlana A.

    2017-03-01

    Conformational properties of the main part (excluding sbnd OC3H7 radicals) of the p-n-propyloxybenzoic (A1) and p-n-propyloxycinnamic (A2) acids molecules (relating to mesomorphic compounds) as well as p-n-propyloxybenzoic acid pyridine ester (B1) and p-n-propyloxyphenylazopyridine (B2) molecules (relating to non-mesomorphic compounds) were studied by DFT(B3LYP)/cc-pVTZ method. It was shown that the main parts of A1 and A2 acids are rigid. The barrier to internal rotation of pyridine fragment in the B1 and B2 molecules depends on the nature of the bridging group. It was determined that all studied A1⋯B1, A2⋯B1 and A2⋯B2 complexes are characterized by a strong hydrogen bond. The binding energy of complexes (≈14 kcal/mol, with BSSE corrections, DFT(B97D)/6-311++G**) exceeds the energy per hydrogen bond in the corresponding acid dimers (≈10 kcal/mol). The structural non-rigidity of A⋯B complexes is mainly caused by possibility of sbnd OC3H7 radicals internal rotation and A and B molecules rotation about the (H)O⋯N line. The characteristics of intermolecular hydrogen bonds were determined by NBO-analysis. The obtained results indicate that examined complexes correspond to the basic requirements to mesogen molecular forms. The thermodynamic functions of the gas-phase complexation reactions (idealized model of the complexes formation in the condensed state) were calculated. Preliminary studies of mesogen-non-mesogen A1⋯B2 system by differential scanning calorimetry and polarizing optical microscopy, showed that it has mesomorphic properties.

  5. Absorption spectra and spectral-kinetic characteristics of the fluorescence of Sanguinarine in complexes with polyelectrolytes and DNA

    NASA Astrophysics Data System (ADS)

    Motevich, I. G.; Strekal, N. D.; Nowicky, J. W.; Maskevich, S. A.

    2010-07-01

    The absorption spectra and stationary and time resolved fluorescence spectra of the isoquinoline alkaloid sanguinarine are studied in aqueous media and during interactions with synthetic polyelectrolytes (polystyrene sulfonate and polyallylamine) and a natural polyelectrolyte (DNA).

  6. Characteristics of hydrogen sulfide removal in a carrier-packed biological deodorization system.

    PubMed

    Shinabe; Oketani; Ochi; Kanchanatawee; Matsumura

    2000-07-01

    The relationship between the characteristics of carriers in a carrier-packed biological deodorization (CPBD) reactor and the efficiency of H(2)S removal was studied. From the result of a deodorization experiment using three different carriers (each of which obtained a high level of H(2)S removal), the best carrier was cylindrical and the surface and inside of the carrier had macro pores (about 1mm in diameter). The carrier also had large porosity and surface area. Each of these characteristics, with the exception of the large surface area, corresponded to the characteristics that resulted in a high discharge efficiency of sulfuric acid. A deodorization experiment using two carriers that differed only in size showed that K(G)a was a very important operating parameter of the apparatus. Therefore, the size of the carrier should be as small as possible within certain technical limitations.

  7. Characteristics and oil absorption in deep-fat fried batter prepared from ball-milled wheat flour.

    PubMed

    Thanatuksorn, Pariya; Kajiwara, Kazuhito; Suzuki, Toru

    2010-01-15

    The porous structure generated during frying influences oil absorption and textural qualities. The alteration in physical properties of wheat flour is suspected to affect the structure formation. The present study investigated the effect of physicochemical changes in wheat flour by the ball-milling process on structure formation and consequently oil absorption of a fried wheat flour batter model. Batter models containing 600 g kg(-1) moisture were made of 0-10 h ball-milled wheat flour and then fried in frying oil at 150 degrees C for 1-7 min. The samples made of milled flour possess larger pores and exhibit lower oil absorption than sample made of 0 h milled flour. The fracture force of a fried sample prepared from 5 and 10 h milled flour is lower than that of a sample prepared from 0 h milled flour. The decrease in glass transition temperature (T(g)) and melting temperature (T(m)) of milled flour affect the microstructure formation in the fried wheat flour batter. The microstructure is responsible for oil absorption and fracturability in fried food. The samples made of flour of longer ball-milling time have lower oil absorption and higher crispness. Ball-milling may be a tool to produce mechanically modified wheat flour which can reduce oil absorption for fried batter. Copyright (c) 2009 Society of Chemical Industry.

  8. Prelaunch self-discharge and charge-acceptance characteristics of the Hubble Space Telescope nickel hydrogen batteries

    NASA Technical Reports Server (NTRS)

    Lanier, John R., Jr.; Bush, John R., Jr.

    1991-01-01

    Tests performed at NASA/MSFC on the Hubble Space Telescope (HST) nickel-hydrogen batteries (flight spare module and flight spare battery) were used to determine self-discharge and charge-acceptance characteristics when the batteries were exposed to charged wet-stand conditions, pulse charging on the launch pad, and battery capacity at solar array deployment. An equation is presented which was used to predict the capacity that would be available in the HST NiH2 batteries after an extended stand time on the launch pad plus up to 2 days on orbit prior to solar array deployment (either ground power or orbiter power were used to supply HST loads until shortly before the solar arrays were deployed). It is shown that a fairly accurate estimate of the available capacity was made.

  9. Investigation of Oxygen and Hydrogen Associated Charge Trapping and Electrical Characteristics of Silicon Nitride Films for Mnos Devices.

    NASA Astrophysics Data System (ADS)

    Xu, Dan

    Silicon nitride (Si_3N _4) and silicon oxynitride (SiO _{rm x}N_ {rm y}) films in the form of metal -nitride-oxide-silicon (MNOS) structures were investigated to determine the correlation between their electrical characteristics and the nature of the chemical bonding so as to provide guidelines for the next generation of nonvolatile memory devices. The photoionization cross section of electron traps in the oxynitride films of MNOS devices were also measured as a function photon energy and oxygen concentration of the silicon oxynitride films. An effective photoionization cross section associated with electron traps was determined to be between 4.9 times 10 ^{-19} cm^2 to 10.8 times 10^ {-19} cm^2 over the photon energy of 2.06 eV to 3.1 eV for silicon oxynitride films containing 7 atomic % to 17 atomic % of oxygen. The interface state density of metal-nitride-oxide -silicon (MNOS) devices was investigated as a function of processing conditions. The interface state density around the midgap of the oxide-silicon interface of the MNOS structures for deposition temperature between 650^ circC to 850^circC increased from 1.1 to 8.2 times 10 ^{11} cm^ {-2}eV^{-1}, for as-deposited silicon nitride films; but decreased from 5.0 to 3.5 times 10^ {11} cm^{-2} eV^{-1}, for films annealed in nitrogen at 900^circC for 60 minutes; and further decreased and remained constant at 1.5 times 10^{11 } cm^{-2}eV ^{-1}, for films which were further annealed in hydrogen at 900^ circC for an additional 60 minutes. The interface state density increase was due to an increase in the loss of hydrogen at the interfacial region and also due to an increase in the thermal stress caused by differences in thermal expansion coefficients of silicon nitride and silicon dioxide films at higher deposition temperatures. The interface state density was subject to two opposing influences; an increase by thermal stress, and a reduction by hydrogen compensation of these states. The photocurrent-voltage (photo

  10. Optical absorption in amorphous silicon

    SciTech Connect

    O`Leary, S.K.; Zukotynski, S.; Perz, J.M.; Sidhu, L.S.

    1996-12-31

    The role that disorder plays in shaping the form of the optical absorption spectrum of hydrogenated amorphous silicon is investigated. Disorder leads to a redistribution of states, which both reduces the Tauc gap and broadens the absorption tail. The observed relationship between the Tauc gap and the breadth of the absorption tail is thus explained.

  11. Synthesis and characteristics of (Hydrogenated) ferulic acid derivatives as potential antiviral agents with insecticidal activity

    PubMed Central

    2013-01-01

    Background Plant viruses cause many serious plant diseases and are currently suppressed with the simultaneous use of virucides and insecticides. The use of such materials, however, increases the amounts of pollutants in the environment. To reduce environmental contaminants, virucides with insecticidal activity is an attractive option. Results A series of substituted ferulic acid amide derivatives 7 and the corresponding hydrogenated ferulic acid amide derivatives 13 were synthesized and evaluated for their antiviral and insecticidal activities. The majority of the synthesized compounds exhibited good levels of antiviral activity against the tobacco mosaic virus (TMW), with compounds 7a, 7b and 7d in particular providing higher levels of protective and curative activities against TMV at 500 μg/mL than the control compound ribavirin. Furthermore, these compounds displayed good insecticidal activities against insects with piercing-sucking mouthparts, which can spread plant viruses between and within crops. Conclusions Two series of ferulic acid derivatives have been synthesized efficiently. The bioassay showed title compounds not only inhibit the plant viral infection, but also prevented the spread of plant virus by insect vectors. These findings therefore demonstrate that the ferulic acid amides represent a new template for future antiviral studies. PMID:23409923

  12. Influence of Hydrogenation on the Amorphous-to-Crystalline Phase Transition Characteristics of Ge2Sb2Te5 and Ge8Sb2Te11 Thin Films

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Won; Lim, Woo-Sik; Kim, Tae-Wan; Lee, Hyun-Yong

    2008-07-01

    The characteristics of amorphous-to-crystalline phase transformation in the hydrogenated Ge2Sb2Te5 and Ge8Sb2Te11 thin films were investigated by X-ray diffraction (XRD), optical transmittance (TOP), and nano-pulse reflection response. The hydrogenation was conducted under a H2 pressure (PH) of 20 atm and an annealing temperature (Ta) of 100 and 200 °C. The incorporation of hydrogens into the chalcogenide films was verified by secondary ion mass spectrometry (SIMS) depth profile. The variation of H-signals in the SIMS profile was apparently compensated by the variation of Sb and Ge signals rather than by that of Te. The results measured in hydrogenated films were compared with those in the as-deposited and post-annealed films at Ta for 4 h in pure N2 atmosphere. The hydrogenation effects led to very different dependences between the Ge2Sb2Te5 and Ge8Sb2Te11 thin films. Amorphous-to-crystalline phase-transition speed was evaluated via nano-pulse reflection response measurement. The hydrogenation inhibited the transition of Ge2Sb2Te5 but hardly affected that of Ge8Sb2Te11. In particular, the amorphous-to-crystalline transition in the hydrogenated Ge8Sb2Te11 film was very stable.

  13. METAL HYDRIDE HYDROGEN COMPRESSORS: A REVIEW

    SciTech Connect

    Bowman Jr, Robert C; Yartys, Dr. Volodymyr A.; Lototskyy, Dr. Michael V; Pollet, Dr. B.G.

    2014-01-01

    Metal hydride (MH) thermal sorption compression is an efficient and reliable method allowing a conversion of energy from heat into a compressed hydrogen gas. The most important component of such a thermal engine the metal hydride material itself should possess several material features in order to achieve an efficient performance in the hydrogen compression. Apart from the hydrogen storage characteristics important for every solid H storage material (e.g. gravimetric and volumetric efficiency of H storage, hydrogen sorption kinetics and effective thermal conductivity), the thermodynamics of the metal-hydrogen systems is of primary importance resulting in a temperature dependence of the absorption/desorption pressures). Several specific features should be optimized to govern the performance of the MH-compressors including synchronisation of the pressure plateaus for multi-stage compressors, reduction of slope of the isotherms and hysteresis, increase of cycling stability and life time, together with challenges in system design associated with volume expansion of the metal matrix during the hydrogenation. The present review summarises numerous papers and patent literature dealing with MH hydrogen compression technology. The review considers (a) fundamental aspects of materials development with a focus on structure and phase equilibria in the metal-hydrogen systems suitable for the hydrogen compression; and (b) applied aspects, including their consideration from the applied thermodynamic viewpoint, system design features and performances of the metal hydride compressors and major applications.

  14. High capacity hydrogen storage nanocomposite materials

    DOEpatents

    Zidan, Ragaiy; Wellons, Matthew S

    2015-02-03

    A novel hydrogen absorption material is provided comprising a mixture of a lithium hydride with a fullerene. The subsequent reaction product provides for a hydrogen storage material which reversibly stores and releases hydrogen at temperatures of about 270.degree. C.

  15. [Characteristics of the absorption spectra of the mixtures of C42(Al), C32 (Si) and so on].

    PubMed

    Chen, W

    1998-12-01

    The mixtures containing C42 (A1), C32 (Si), C30 (Ca) and C28 (Fe) are produced by means of arc discharge and He gas convection. The spectra are measured and compared with the absorption spectra of all carbon molecules. The result shows that after imbeded in all carbon molecules, the Al, Si, Ca and Fe atoms do not change the positions of the absorption peak of original molecules, but only change the probability of pi --> pi* transition and n --> pi* transition of these molecules.

  16. Effect of air-pressure on room temperature hydrogen sensing characteristics of nanocrystalline doped tin oxide MEMS-based sensor.

    PubMed

    Shukla, Satyajit; Ludwig, Lawrence; Cho, Hyoung J; Duarte, Julian; Seal, Sudipta

    2005-11-01

    Nanocrystalline indium oxide (In2O3)-doped tin oxide (SnO2) thin film sensor has been sol-gel dip-coated on a microelectrochemical system (MEMS) device using a sol-gel dip-coating technique. Hydrogen (H2) at ppm-level has been successfully detected at room temperature using the present MEMS-based sensor. The room temperature H2 sensing characteristics (sensitivity, response and recovery time, and recovery rate) of the present MEMS-based sensor has been investigated as a function of air-pressure (50-600 Torr) with and without the ultraviolet (UV) radiation exposure. It has been demonstrated that, the concentration of the surface-adsorbed oxygen-ions (which is related to the sensor-resistance in air), the ppm-level H2, and the oxygen (O2) partial pressure are the three major factors, which determine the variation in the room temperature H2 sensing characteristics of the present MEMS-based sensor as a function of air-pressure.

  17. Characteristics and indications of hydrogen and oxygen isotopes distribution in lake ice body.

    PubMed

    Zhen, Zhi-Lei; Li, Chang-You; Zhang, Sheng; Li, Wen-Bao; Shi, Xiao-Hong; Sun, Biao

    2015-01-01

    Stable isotopes have been used to identify the characteristics of precipitation, evaporation, basin hydrology, and residence times. However, lakes in the cold regions are usually covered by ice for 5-6 months. To get a better understanding of stable isotopes characteristics and indications in lake ice bodies, ice and water were sampled during the icebound season in both the ice and water bodies in Dali Lake, and deuterium, oxygen-18 total nitrogen (TN), and the major ions were analyzed. The results showed that deuterium and oxygen-18 compositions (δD-δ¹⁸O) compositions in the ice body were greater than in the water body beneath, scattered on a straight line, and deviating downward from the global meteoric water line in the top right. The ice profile showed that the δD-δ¹⁸O compositions increased from the ice surface downward and decreased near to the bottom. In contrast, the TN and the major ions in the ice decreased from the ice surface downward and increased near to the bottom, meaning that the concentrations of δ¹⁸O had a negative correlation with the concentrations of TN and major ions. These indicated that stable isotopes can be used for tracing the nutriment and ion transport processes in the ice body.

  18. Characteristic coupling time between axial and transverse energy modes for anti-hydrogen in magnetostatic traps

    NASA Astrophysics Data System (ADS)

    Zhong, Mike; Fajans, Joel

    2016-10-01

    For upcoming ALPHA collaboration laser spectroscopy and gravity experiments, the nature of the chaotic trajectories of individual antihydrogen atoms trapped in the octupole Ioffe magnetic trap is of importance. Of particular interest for experimental design is the coupling time between the axial and transverse modes of energy for the antihydrogen atoms. Using Monte Carlo simulations of semiclassical dynamics of antihydrogen trajectories, we quantify this characteristic coupling time between axial and transverse modes of energy. There appear to be two classes of trajectories: for orbits whose axial energy is higher than 10% of the total energy, the axial energy varies chaotically on the order of 1-10 seconds, whereas for orbits whose axial energy is around 10% of the total energy, the axial energy remains nearly constant on the order of 1000 seconds or longer. Furthermore, we search through parameter -space to find parameters of the magnetic trap that minimize and maximize this characteristic coupling time. This work was supported by the UC Berkeley Summer Undergraduate Research Fellowship, the Berkeley Research Computing program, the Department of Energy contract DE-FG02-06ER54904, and the National Science Foundation Grant 1500538-PHY.

  19. [Study on cadmium absorption in pumpkin by atomic absorption spectrophotometry].

    PubMed

    Li, Zhen-Xia; Jing, Rui-Jun; Dong, Wei-Hua; Li, Xin-Zheng; Liu, Hong

    2006-08-01

    A study was carried out on the characteristic of cadmium absorption in pumpkin by atomic absorption spectrophotometer. The results show that the cadmium absorption amount in pumpkin increased with the increase in cadmium concentration. Meanwhile the cadmium absorption amount in pumpkin increased with time. Eight hours after being cultured in the liquid, the cadmium absorption amount became saturated. The cadmium absorption rate reached the peak after 2 hours, then the absorption rate gradually reduced. The cadmium absorption amount in pumpkin is less in acid or alkali compared with neutral condition. And the absorption amount became minimum in pH 3, while maximum in pH 7.

  20. Hydrogen supply system

    SciTech Connect

    Teitel, R.J.

    1981-11-24

    A system for supplying hydrogen to an apparatus which utilizes hydrogen contains a metal hydride hydrogen supply component and a microcavity hydrogen storage hydrogen supply component which in tandem supply hydrogen for the apparatus. The metal hydride hydrogen supply component includes a first storage tank filled with a composition which is capable of forming a metal hydride of such a nature that the hydride will release hydrogen when heated but will absorb hydrogen when cooled. This first storage tank is equipped with a heat exchanger for both adding heat to and extracting heat from the composition to regulate the absorption/deabsorption of hydrogen from the composition. The microcavity hydrogen storage hydrogen supply component includes a second tank containing the microcavity hydrogen supply. The microcavity hydrogen storage contains hydrogen held under high pressure within individual microcavities. The hydrogen is released from the microcavities by heating the cavities. This heating is accomplished by including within the tank for the microcavity hydrogen storage a heating element.

  1. Studies on the de/re-hydrogenation characteristics of nanocrystalline MgH2 admixed with carbon nanofibres

    NASA Astrophysics Data System (ADS)

    Shahi, Rohit R.; Raghubanshi, Himanshu; Shaz, M. A.; Srivastava, O. N.

    2012-09-01

    In the present investigation, we have synthesized different morphologies of carbon nanofibres (CNFs) to investigate their catalytic effect on the hydrogenation characteristics of 25 h ball-milled MgH2 (nano MgH2). The TEM analysis reveals that 25 h of ball-milling leads to the formation of nanocrystalline particles with size ranging between 10 and 20 nm. Different morphologies of CNFs were synthesized by catalytic thermal decomposition of acetylene (C2H2) gas over LaNi5 alloy. Helical carbon nanofibers (HCNFs) were formed at a temperature 650 °C. By increasing the synthesis temperature to 750 °C, planar carbon nanofibres were formed. In order to explore the effectiveness of CNFs towards lowering the decomposition temperature, TPD experiments (at heating rate 5 °C/min) were performed for nano MgH2 with and without CNFs. It was found that the decomposition temperature is reduced to ~334 and ~300 °C from 367 °C for the PCNF and HCNF catalysed nano MgH2. It is also found that HCNF admixed nano MgH2 absorbs ~5.25 wt% within 10 min as compared with pristine nano MgH2, which absorbs only ~4.2 % within the same time and same condition of temperature and pressure. Thus the HCNF possesses better catalytic activity than PCNF. These different levels of improvement in hydrogenation properties of HCNF catalysed nano MgH2 is attributed to the morphology of the CNFs.

  2. [Determination method of muscone in rat intestinal perfusate by GC-MS/MS and its intestinal absorption kinetic characteristics in rats].

    PubMed

    Zou, Liang; Lin, Junzhi; Wang, Zhanguo; Xu, Lijia; Wang, Ping; Zhao, Gang; Luo, Jieying

    2012-08-01

    To establish the method for determining muscone in rat intestinal perfusate by GC-MS/MS and study its intestinal absorption kinetic characteristics in rats. The GC-MS/MS method was used to determine the content of muscone in rat intestinal circulation fluid. In situ intestinal circulation perfusion was adopted to study absorption kinetics of muscone in rats. Muscone was proved to be well absorbed in each section of small intestine. Its absorption rate constants (Ka) and the absorption rate (A) in the rat intestine showed duodenum > jejunum (P < 0.05) , duodenum > ileum (P < 0.01). Its Ka, A and t1/2 in rat small intestine was 0.990 h(-1) , 43.58% and 0.705h, respectively. Muscone was well absorbed in each intestinal section, with duodenum better than jejunum (Ka, T1/2, P < 0.05) significantly better than ileum (Ka, T1/2, P < 0.01; A, P < 0.05). There is no obvious statistical difference between jejunum and ileum.

  3. Partial conversion of hydrocarbons to syngas and hydrogen in volumetric radiation burners as a prospective way to enhance the performance characteristics of power engines

    NASA Astrophysics Data System (ADS)

    Arutyunov, V. S.; Shmelev, V. M.; Shapovalova, O. V.; Rakhmetov, A. N.; Strekova, L. N.

    2013-03-01

    New type of syngas generator based on the partial conversion of natural gas (methane) or heavier hydrocarbons in volumetric permeable matrix burners in the conditions of locked infrared (IR) radiation is suggested as a high-productive, adaptable, and rather simple way of syngas and hydrogen production for various low-scale applications including enhancing the performance characteristics of power engines.

  4. Preliminary evaluation of the air and fuel specific-impulse characteristics of several potential ram-jet fuels IV : hydrogen, a-methylnaphthalene, and carbon / Benson E. Gammon

    NASA Technical Reports Server (NTRS)

    Gammon, Benson E

    1951-01-01

    A preliminary analytical evaluation of the air and fuel specific-impulse characteristics of hydrogen, a-methylnapthalene, and graphite carbon has been made. Adiabatic constant-pressure combustion flame temperatures for each fuel at several equivalence ratios were calculated for an initial air temperature of 560 degrees R and a pressure of 2 atmospheres.

  5. Influence of resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion

    NASA Astrophysics Data System (ADS)

    Potapkin, A. V.; Moskvichev, D. Yu.

    2008-09-01

    The influence of acoustic resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion was experimentally examined. In the study, resonators having identical throats and different cavity diameters were used. For fixed-volume resonators the best propulsion performance characteristics were achieved in the case in which the cavity diameter differed little from the resonator throat diameter.

  6. Ultrafast carrier dynamics unravel role of surface ligands and metal domain size on the photocatalytic hydrogen evolution efficiency of Au-tipped CdS nanorods: an ultrafast transient absorption spectroscopy study

    NASA Astrophysics Data System (ADS)

    Ben-Shahar, Yuval; Kriegel, Ilka; Scotognella, Francesco; Waiskopf, Nir; Dal Conte, Stefano; Moretti, Luca; Cerullo, Giulio; Rabani, Eran; Banin, Uri

    2017-02-01

    Semiconductor-metal hybrid nanostructures are interesting materials for photocatalysis. Their tunable properties offer a highly controllable platform to design light-induced charge separation, a key to their function in photocatalytic water splitting. Hydrogen evolution quantum yields are influenced by factors as size, shape, material and morphology of the system, additionally the surface coating or the metal domain size play a dominant role. In this paper we present a study on a well-defined model system of Au-tipped CdS nanorods. We use transient absorption spectroscopy to get insights into the charge carrier dynamics after photoexcitation of the bandgap of CdS nanorods. The study of charge transfer processes combined with the hydrogen evolution efficiency unravels the effects of surface coating and the gold tip size on the photocatalytic efficiency. Differences in efficiency with various surface ligands are primarily ascribed to the effects of surface passivation. Surface trapping of charge carriers is competing with effective charge separation, a prerequisite for photocatalysis, leading to the observed lower hydrogen production quantum yields. Interestingly, non-monotonic hydrogen evolution efficiency with size of the gold tip is observed, resulting in an optimal metal domain size for the most efficient photocatalysis. These results are explained by the sizedependent interplay of the metal domain charging and the relative band-alignments. Taken together our findings are of major importance for the potential application of hybrid nanoparticles as photocatalysts.

  7. Triacylglycerol composition, physico-chemical characteristics and oxidative stability of interesterified canola oil and fully hydrogenated cottonseed oil blends.

    PubMed

    Imran, Muhammad; Nadeem, Muhammad

    2015-10-29

    Partial hydrogenation process is used worldwide to produce shortening, baking, and pastry margarines for food applications. However, demand for such products is decreased during last decade due to their possible links to consumer health and disease. This has raised the need to replace hydrogenation with alternative acceptable interesterification process which has advantage in context of modifying the physico-chemical properties of edible fat-based products. Therefore, the main mandate of research was the development of functional fat through chemical interesterification of canola oil (CaO) and fully hydrogenated cottonseed oil (FHCSO) mixtures. Blends were prepared in the proportions of 75:25 (T1), 50:50 (T2) and 25:75 (T3) of CaO:FHCSO (w/w). Interesterification was performed using sodium methoxide (0.2 %) as catalyst at 120 °C, under reduced pressure and constant agitation for 60 minutes. The non-interesterified and interesterified CaO:FHCSO blends were evaluated for triacylglycerol (TAG) composition, physico-chemical characteristics, oxidative stability and consumer acceptability at 0, 30 and 60 days of storage interval. The oleic acid (58.3 ± 0.6 %) was predominantly present in CaO while the contents of stearic acid (72 ± 0.8 %) were significantly higher in FHCSO. Maximum trisaturated (S3) contents (63.9 ± 0.5 %) were found in T3 while monounsaturated (S2U), diunsaturated (U2S) and triunsaturated (U3) contents were quite low in T2 and T3 before interesterification. A marked reduction in S3 and U3 contents with concomitant increase in S2U and U2S contents was observed for all CaO:FHCSO blends on interesterification. During storage, the changes in S3, S2U and U2S contents were not found significant (p ≥ 0.05). However, maximum decrease 13 %, 7.5 and 5.6 % in U3 contents for T1, T2 and T3 was noted after 60-days of interesterification, respectively. The Lovibond color R, melting point, refractive index, specific gravity, peroxide and free

  8. The Redshifted Hydrogen Balmer and Metastable He 1 Absorption Line System in Mini-FeLoBAL Quasar SDSS J112526.12+002901.3: A Parsec-scale Accretion Inflow?

    NASA Astrophysics Data System (ADS)

    Shi, Xi-Heng; Jiang, Peng; Wang, Hui-Yuan; Zhang, Shao-Hua; Ji, Tuo; Liu, Wen-Juan; Zhou, Hong-Yan

    2016-10-01

    The accretion of the interstellar medium onto central super-massive black holes is widely accepted as the source of the gigantic energy released by the active galactic nuclei. However, few pieces of observational evidence have been confirmed directly demonstrating the existence of the inflows. The absorption line system in the spectra of quasar SDSS J112526.12+002901.3 presents an interesting example in which the rarely detected hydrogen Balmer and metastable He i absorption lines are found redshifted to the quasar's rest frame along with the low-ionization metal absorption lines Mg ii, Fe ii, etc. The repeated SDSS spectroscopic observations suggest a transverse velocity smaller than the radial velocity. The motion of the absorbing medium is thus dominated by infall. The He i* lines present a powerful probe to the strength of ionizing flux, while the Balmer lines imply a dense environment. With the help of photoionization simulations, we find that the absorbing medium is exposed to the radiation with ionization parameter U ≈ 10-1.8, and the density is n({{H}})≈ {10}9 {{cm}}-3. Thus the absorbing medium is located ˜4 pc away from the central engine. According to the similarity in the distance and physical conditions between the absorbing medium and the torus, we strongly propose the absorption line system as a candidate for the accretion inflow, which originates in the inner surface of the torus.

  9. A study on the characteristics of the deflagration of hydrogen-air mixture under the effect of a mesh aluminum alloy.

    PubMed

    Pang, Lei; Wang, Chenxu; Han, Mengxing; Xu, Zilong

    2015-12-15

    Mesh aluminum alloys (MAAs) have been widely used in military and civilian applications to suppress the explosion of flammable gases (fluids) inside containers. However, MAAs have not been tested in or applied to the hydrogen suppression-explosions. Hence, a typical MAA product, i.e., one that has been in wide use, is selected as the experimental material in the present study. The characteristics of the deflagration of hydrogen-air mixture inside an MAA-filled tube are investigated, and the effects of the filling density of the MAA and the concentration of hydrogen in air on the deflagration are examined. The suppressing effect of the MAA on the deflagration of hydrogen-air mixture is compared with its effect on the deflagration of a typical hydrocarbon fuel in air. The results show that not only is the existing MAA product unable to effectively suppress the deflagration of hydrogen-air mixture, but it also increases the maximum explosion pressure, which is opposite to the satisfactory suppressing effect of the MAA product on the deflagration of hydrocarbon fuels such as methane. The results of this study provide a scientific basis for the effective prevention of explosion accidents with hydrogen and for the development of explosion-suppression products. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Time-dependent density functional theory study on the excited-state hydrogen-bonding characteristics of polyaniline in aqueous environment

    NASA Astrophysics Data System (ADS)

    Zhang, Yahong; Duan, Yuping; Liu, Jin

    2017-01-01

    A theoretical study was carried out to study the excited-state of hydrogen-bonding characteristics of polyaniline (PANI) in aqueous environment. The hydrogen-bonded PANI-H2O complexes were studied using first-principles calculations based on density functional theory (DFT). The electronic excitation energies and the corresponding oscillator strengths of the low-lying electronically excited states for hydrogen-bonded complexes were calculated by time-dependent density functional theory (TDDFT). The ground-state geometric structures were optimized, and it is observed that the intermolecular hydrogen bonds Csbnd N ⋯ Hsbnd O and Nsbnd H ⋯ Osbnd H were formed in PANI-H2O complexes. The formed hydrogen bonds influenced the bond lengths, the charge distribution, as well as the spectral characters of the groups involved. It was concluded that all the hydrogen-bonded PANI-H2O complexes were primarily excited to the S1 states with the largest oscillator strength. In addition, the orbital transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) involved intramolecular charge redistribution resulting to increase the electron density of the quinonoid rings.

  11. Theoretical study of the changes in the vibrational characteristics arising from the hydrogen bonding between Vitamin C ( L-ascorbic acid) and H 2O

    NASA Astrophysics Data System (ADS)

    Dimitrova, Yordanka

    2006-02-01

    The vibrational characteristics (vibrational frequencies, infrared intensities and Raman activities) for the hydrogen-bonded system of Vitamin C ( L-ascorbic acid) with five water molecules have been predicted using ab initio SCF/6-31G(d, p) calculations and DFT (BLYP) calculations with 6-31G(d, p) and 6-31++G(d, p) basis sets. The changes in the vibrational characteristics from free monomers to a complex have been calculated. The ab initio and BLYP calculations show that the complexation between Vitamin C and five water molecules leads to large red shifts of the stretching vibrations for the monomer bonds involved in the hydrogen bonding and very strong increase in their IR intensity. The predicted frequency shifts for the stretching vibrations from Vitamin C taking part in the hydrogen bonding are up to -508 cm -1. The magnitude of the wavenumber shifts is indicative of relatively strong OH···H hydrogen-bonded interactions. In the same time the IR intensity and Raman activity of these vibrations increase upon complexation. The IR intensity increases dramatically (up to 12 times) and Raman activity increases up to three times. The ab initio and BLYP calculations show, that the symmetric OH vibrations of water molecules are more sensitive to the complexation. The hydrogen bonding leads to very large red shifts of these vibrations and very strong increase in their IR intensity. The asymmetric OH stretching vibrations of water, free from hydrogen bonding are less sensitive to the complexation than the hydrogen-bonded symmetric O sbnd H stretching vibrations. The increases of the IR intensities for these vibrations are lower and red shifts are negligible.

  12. Theoretical study of the changes in the vibrational characteristics arising from the hydrogen bonding between Vitamin C (L-ascorbic acid) and H2O.

    PubMed

    Dimitrova, Yordanka

    2006-02-01

    The vibrational characteristics (vibrational frequencies, infrared intensities and Raman activities) for the hydrogen-bonded system of Vitamin C (L-ascorbic acid) with five water molecules have been predicted using ab initio SCF/6-31G(d,p) calculations and DFT (BLYP) calculations with 6-31G(d,p) and 6-31++G(d,p) basis sets. The changes in the vibrational characteristics from free monomers to a complex have been calculated. The ab initio and BLYP calculations show that the complexation between Vitamin C and five water molecules leads to large red shifts of the stretching vibrations for the monomer bonds involved in the hydrogen bonding and very strong increase in their IR intensity. The predicted frequency shifts for the stretching vibrations from Vitamin C taking part in the hydrogen bonding are up to -508 cm(-1). The magnitude of the wavenumber shifts is indicative of relatively strong OH...H hydrogen-bonded interactions. In the same time the IR intensity and Raman activity of these vibrations increase upon complexation. The IR intensity increases dramatically (up to 12 times) and Raman activity increases up to three times. The ab initio and BLYP calculations show, that the symmetric OH vibrations of water molecules are more sensitive to the complexation. The hydrogen bonding leads to very large red shifts of these vibrations and very strong increase in their IR intensity. The asymmetric OH stretching vibrations of water, free from hydrogen bonding are less sensitive to the complexation than the hydrogen-bonded symmetric OH stretching vibrations. The increases of the IR intensities for these vibrations are lower and red shifts are negligible.

  13. Optical Absorption and Luminescence Characteristics of LiCaB Glass Doped with Dy3+ and Sm3+

    NASA Astrophysics Data System (ADS)

    Srivastava, P.

    2017-07-01

    The glasses were prepared by a melt quenching technique and characterized by X-ray diffraction (XRD), optical absorption, and luminescence spectral studies. The XRD analysis indicates that the prepared samples are of fully amorphous nature. Optical absorption spectra have been investigated using the Judd-Ofelt theory. Radiative parameters such as transition probabilities, branching ratios, radiative lifetime, and stimulated emission cross section have been evaluated using Judd-Ofelt intensity parameters. The luminescence spectra of both of Dy3+- as well of Sm3+-doped glasses were recorded with the 476 nm line of an Ar+ laser. Based on the values of stimulated emission cross section, radiative transition rate, and branching ratio of the emission transition 4F9/2 → 6H13/2 of Dy3+, it is suggested that 2 mol.% of Dy3+ LiCaB glass is a promising luminescent material for lasing applications.

  14. Absorption characteristics of aerosols over the northwestern region of India: Distinct seasonal signatures of biomass burning aerosols and mineral dust

    NASA Astrophysics Data System (ADS)

    Gogoi, Mukunda M.; Suresh Babu, S.; Krishna Moorthy, K.; Manoj, M. R.; Chaubey, Jai Prakash

    2013-07-01

    Continuous measurements of aerosol black carbon (BC) mass concentrations made over a period of 3 years from a semi-arid, near-coastal, remote and sparsely inhabited location along with satellite-based data of aerosol absorption index, optical depth and extinction profiles in western India are used to characterize the distinct nature of aerosols near the surface and in the free troposphere and their seasonality. Despite being far remote and sparsely inhabited, significant levels of BC are observed in the ambient during winter (1.45 ± 0.71 μg m-3) attributed to biomass burning aerosols, advected to the site from the north and west; while during summer the concentrations are far reduced (0.23 ± 0.11 μg m-3) and represent the apparent background concentrations. The spectral absorption coefficients suggest the BC during summer be mostly of fossil fuel combustions. The strong convective boundary layer dynamics produces significant diurnal variation during winter and modulates to a lesser extent the seasonal variation. Examination of aerosol (absorption) index from OMI data for the study period showed a seasonal pattern that is almost opposite to that seen at the surface; with high aerosol index in summer, showing a significant difference between the surface and columnar aerosol types in summer. MISR and MODIS-derived columnar AOD follow the OMI pattern. Analysis of the vertical profiles of aerosol extinction and volume depolarization ratio (VDR), derived from CALIPSO data indicates the presence of strong dust layers with VDR ˜ 0.3 in the altitude region 4-6 km, contributing to the high aerosol index in the OMI data, while the surface measurements show absorptive properties representing fossil fuel BC aerosols.

  15. Analysis of diffential absorption lidar technique for measurements of anhydrous hydrogen chloride from solid rocket motors using a deuterium fluoride laser

    NASA Technical Reports Server (NTRS)

    Bair, C. H.; Allario, F.

    1977-01-01

    An active optical technique (differential absorption lidar (DIAL)) for detecting, ranging, and quantifying the concentration of anhydrous HCl contained in the ground cloud emitted by solid rocket motors (SRM) is evaluated. Results are presented of an experiment in which absorption coefficients of HCl were measured for several deuterium fluoride (DF) laser transitions demonstrating for the first time that a close overlap exists between the 2-1 P(3) vibrational transition of the DF laser and the 1-0 P(6) absorption line of HCl, with an absorption coefficient of 5.64 (atm-cm) to the -1 power. These measurements show that the DF laser can be an appropriate radiation source for detecting HCl in a DIAL technique. Development of a mathematical computer model to predict the sensitivity of DIAL for detecting anhydrous HCl in the ground cloud is outlined, and results that assume a commercially available DF laser as the radiation source are presented.

  16. Hydrogen sensing characteristics of wet chemical synthesized tailored Mg0.5Zn0.5Fe2O4 nanostructures.

    PubMed

    Mukherjee, K; Majumder, S B

    2010-06-25

    Solution based synthesis routes are attractive for making tailor-made nanostructures for electroceramics in a simple and cost-effective way. The gas sensing characteristics of semiconducting oxide gas sensors strongly depend on the adsorption and desorption of gases over the sensing surface. The morphology of the sensing element is known to influence the adsorption and desorption of gases and thereby the sensing performance of the material. In the present work a Pechini based solution synthesis route is adopted in order to synthesize magnesium zinc ferrite gas sensors in nanoparticle, nanotube and thin film forms. The hydrogen gas sensing characteristics of these sensing elements are compared as a function of test gas concentration and operating temperature. The influences of the morphology of the magnesium zinc ferrite sensing elements on the hydrogen sensing characteristics are discussed.

  17. I-V characteristics of in-plane and out-of-plane strained edge-hydrogenated armchair graphene nanoribbons

    SciTech Connect

    Cartamil-Bueno, S. J. E-mail: rbolivar@ugr.es; Rodríguez-Bolívar, S. E-mail: rbolivar@ugr.es

    2015-06-28

    The effects of tensile strain on the current-voltage (I-V) characteristics of hydrogenated-edge armchair graphene nanoribbons are investigated by using DFT theory. The strain is introduced in two different ways related to the two types of systems studied in this work: in-plane strained systems (A) and out-of-plane strained systems due to bending (B). These two kinds of strain lead to make a distinction among three cases: in-plane strained systems with strained electrodes (A1) and with unstrained electrodes (A2), and out-of-plane homogeneously strained systems with unstrained, fixed electrodes (B). The systematic simulations to calculate the electronic transmission between two electrodes were focused on systems of 8 and 11 dimers in width. The results show that the differences between cases A2 and B are negligible, even though the strain mechanisms are different: in the plane case, the strain is uniaxial along its length; while in the bent case, the strain is caused by the arc deformation. Based on the study, a new type of nanoelectromechanical system solid state switching device is proposed.

  18. Tribo-characteristics of self-lubricating ball bearings for the LE-7 liquid hydrogen rocket-turbopump

    NASA Astrophysics Data System (ADS)

    Nosaka, Masataka; Oike, Mamoru; Kikuchi, Masataka; Kamijo, Kenjiro; Tajiri, Masanori

    1993-07-01

    The tribo characteristics of self-lubricating 40-mm-bore ball bearings with a retainer of glass cloth-polytetrafluoroethylene (PTFE) laminate, which has elliptical pockets with a large pocket clearance, were tested under thrust loads at speeds up to 50,000 rpm, 2 million DN, in liquid hydrogen (LH2) and in liquid nitrogen (LN2). During testing, the bearing torque, outer-race temperature, and electric resistance between the inner and outer races were monitored to verify the formation and rupture of a PTFE transfer film. Testing showed that the bearings having the elliptical retainer pockets were superior to the conventional bearings with circular pockets. It was determined that, at the maximum inner race spinning velocity of about 5 m/s, a PTFE transfer film could sustain the maximum Hertz stress, up to about 2000 N/sq mm, in LH2, without severe film rupture resulting in bearing seizure. In LN2, the critical load capacity of PTFE transfer film with bearing seizure was about 2700 N/sq mm.

  19. Tribo-characteristics of self-lubricating ball bearings for the LE-7 liquid hydrogen rocket-turbopump

    SciTech Connect

    Nosaka, Masataka; Oike, Mamoru; Kikuchi, Masataka; Kamijo, Kenjiro; Tajiri, Masanori National Aerospace Lab., Kakuda NTN Corp., Aerospace Bearing Engineering Dept., Kuwana )

    1993-07-01

    The tribo characteristics of self-lubricating 40-mm-bore ball bearings with a retainer of glass cloth-polytetrafluoroethylene (PTFE) laminate, which has elliptical pockets with a large pocket clearance, were tested under thrust loads at speeds up to 50,000 rpm, 2 million DN, in liquid hydrogen (LH2) and in liquid nitrogen (LN2). During testing, the bearing torque, outer-race temperature, and electric resistance between the inner and outer races were monitored to verify the formation and rupture of a PTFE transfer film. Testing showed that the bearings having the elliptical retainer pockets were superior to the conventional bearings with circular pockets. It was determined that, at the maximum inner race spinning velocity of about 5 m/s, a PTFE transfer film could sustain the maximum Hertz stress, up to about 2000 N/sq mm, in LH2, without severe film rupture resulting in bearing seizure. In LN2, the critical load capacity of PTFE transfer film with bearing seizure was about 2700 N/sq mm. 10 refs.

  20. Probing the global potential energy minimum of (CH2O)2: THz absorption spectrum of (CH2O)2 in solid neon and para-hydrogen.

    PubMed

    Andersen, J; Voute, A; Mihrin, D; Heimdal, J; Berg, R W; Torsson, M; Wugt Larsen, R

    2017-06-28

    The true global potential energy minimum configuration of the formaldehyde dimer (CH2O)2, including the presence of a single or a double weak intermolecular CH⋯O hydrogen bond motif, has been a long-standing subject among both experimentalists and theoreticians as two different energy minima conformations of Cs and C2h symmetry have almost identical energies. The present work demonstrates how the class of large-amplitude hydrogen bond vibrational motion probed in the THz region provides excellent direct spectroscopic observables for these weak intermolecular CH⋯O hydrogen bond motifs. The combination of concentration dependency measurements, observed isotopic spectral shifts associated with H/D substitutions and dedicated annealing procedures, enables the unambiguous assignment of three large-amplitude infrared active hydrogen bond vibrational modes for the non-planar Cs configuration of (CH2O)2 embedded in cryogenic neon and enriched para-hydrogen matrices. A (semi)-empirical value for the change of vibrational zero-point energy of 5.5 ± 0.3 kJ mol(-1) is proposed for the dimerization process. These THz spectroscopic observations are complemented by CCSD(T)-F12/aug-cc-pV5Z (electronic energies) and MP2/aug-cc-pVQZ (force fields) electronic structure calculations yielding a (semi)-empirical value of 13.7 ± 0.3 kJ mol(-1) for the dissociation energy D0 of this global potential energy minimum.

  1. Probing the global potential energy minimum of (CH2O)2: THz absorption spectrum of (CH2O)2 in solid neon and para-hydrogen

    NASA Astrophysics Data System (ADS)

    Andersen, J.; Voute, A.; Mihrin, D.; Heimdal, J.; Berg, R. W.; Torsson, M.; Wugt Larsen, R.

    2017-06-01

    The true global potential energy minimum configuration of the formaldehyde dimer (CH2O)2, including the presence of a single or a double weak intermolecular CH⋯O hydrogen bond motif, has been a long-standing subject among both experimentalists and theoreticians as two different energy minima conformations of Cs and C2h symmetry have almost identical energies. The present work demonstrates how the class of large-amplitude hydrogen bond vibrational motion probed in the THz region provides excellent direct spectroscopic observables for these weak intermolecular CH⋯O hydrogen bond motifs. The combination of concentration dependency measurements, observed isotopic spectral shifts associated with H/D substitutions and dedicated annealing procedures, enables the unambiguous assignment of three large-amplitude infrared active hydrogen bond vibrational modes for the non-planar Cs configuration of (CH2O)2 embedded in cryogenic neon and enriched para-hydrogen matrices. A (semi)-empirical value for the change of vibrational zero-point energy of 5.5 ± 0.3 kJ mol-1 is proposed for the dimerization process. These THz spectroscopic observations are complemented by CCSD(T)-F12/aug-cc-pV5Z (electronic energies) and MP2/aug-cc-pVQZ (force fields) electronic structure calculations yielding a (semi)-empirical value of 13.7 ± 0.3 kJ mol-1 for the dissociation energy D0 of this global potential energy minimum.

  2. A multiphase mixture model for substrate concentration distribution characteristics and photo-hydrogen production performance of the entrapped-cell photobioreactor.

    PubMed

    Guo, Cheng-Long; Cao, Hong-Xia; Pei, Hong-Shan; Guo, Fei-Qiang; Liu, Da-Meng

    2015-04-01

    A multiphase mixture model was developed for revealing the interaction mechanism between biochemical reactions and transfer processes in the entrapped-cell photobioreactor packed with gel granules containing Rhodopseudomonas palustris CQK 01. The effects of difference operation parameters, including operation temperature, influent medium pH value and porosity of packed bed, on substrate concentration distribution characteristics and photo-hydrogen production performance were investigated. The results showed that the model predictions were in good agreement with the experimental data reported. Moreover, the operation temperature of 30 °C and the influent medium pH value of 7 were the most suitable conditions for photo-hydrogen production by biodegrading substrate. In addition, the lower porosity of packed bed was beneficial to enhance photo-hydrogen production performance owing to the improvement on the amount of substrate transferred into gel granules caused by the increased specific area for substrate transfer in the elemental volume.

  3. Development of a serum-free human cornea construct for in vitro drug absorption studies: the influence of varying cultivation parameters on barrier characteristics.

    PubMed

    Hahne, Matthias; Reichl, Stephan

    2011-09-15

    The increased use of ophthalmic products in recent years has led to an increased demand for in vitro and in vivo transcorneal drug absorption studies. Cell-culture models of the human cornea can avoid several of the disadvantages of widely used animal experimental models, including ethical concerns and poor standardisation. This study describes the development of a serum-free cultivated, three-dimensional human cornea model (Hemicornea, HC) for drug absorption experiments. The impact of varying cultivation conditions on the corneal barrier function was analysed and compared with excised rabbit and porcine corneas. The HC was cultivated on permeable polycarbonate filters using immortalised human keratocytes and a corneal epithelial cell line. The equivalence to native tissue was investigated through absorption studies using model substances with a wide range of molecular characteristics, including hydrophilic sodium fluorescein, lipophilic rhodamine B and fluorescein isothiocyanate (FITC)-labelled macromolecule dextran. To study the intra-laboratory repeatability and construct cultivation, the permeation studies were performed independently by different researchers. The HC exhibited a permeation barrier in the same range as excised animal corneas, high reproducibility and a lower standard deviation. Therefore, the HC could be a promising in vitro alternative to ex vivo corneal tissues in preclinical permeation studies.

  4. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    PubMed

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  5. Bile salts and calcium absorption.

    PubMed

    Webling, D D; Holdsworth, E S

    1966-09-01

    1. The study of the effect of bile salts on enhancing calcium absorption in the rachitic chick has been extended to bile salts not present in chick bile, e.g. glycine conjugates and bile alcohol sulphates. 2. Bile and bile salts cause an increase in calcium absorption from sparingly soluble calcium hydrogen phosphate when compared with a suspension of calcium hydrogen phosphate in saline. 3. If the bile ducts of normal rats are tied the absorption of calcium from calcium hydrogen phosphate decreases but can be restored by giving bile salts with the calcium salt. 4. Bile salts increase solubility in water of the sparingly soluble calcium salts, phytate and phosphate at pH values between 6 and 8. 5. Bile salts increase the solubility in lipid solvents of calcium in approximately the same proportion as they increase the absorption of calcium from the gut. 6. The physiological role of bile in calcium absorption and its mode of action are discussed.

  6. Predicting laser-induced bulk damage and conditioning for deuterated potassium di-hydrogen phosphate crystals using ADM (absorption distribution model)

    SciTech Connect

    Liao, Z M; Spaeth, M L; Manes, K; Adams, J J; Carr, C W

    2010-02-26

    We present an empirical model that describes the experimentally observed laser-induced bulk damage and conditioning behavior in deuterated Potassium dihydrogen Phosphate (DKDP) crystals in a self-consistent way. The model expands on an existing nanoabsorber precursor model and the multi-step absorption mechanism to include two populations of absorbing defects, one with linear absorption and another with nonlinear absorption. We show that this model connects previously uncorrelated small-beam damage initiation probability data to large-beam damage density measurements over a range of ns pulse widths relevant to ICF lasers such as the National Ignition Facility (NIF). In addition, this work predicts the damage behavior of laser-conditioned DKDP and explains the upper limit to the laser conditioning effect. The ADM model has been successfully used during the commissioning and early operation of the NIF.

  7. A mixed quantum-classical molecular dynamics study of the hydroxyl stretch in methanol/carbon tetrachloride mixtures: equilibrium hydrogen-bond structure and dynamics at the ground state and the infrared absorption spectrum.

    PubMed

    Kwac, Kijeong; Geva, Eitan

    2011-07-28

    We present a mixed quantum-classical molecular dynamics study of the structure and dynamics of the hydroxyl stretch in methanol/carbon tetrachloride mixtures. One of the methanol molecules is tagged, and its hydroxyl stretch is treated quantum-mechanically, while the remaining degrees of freedom are treated classically. The adiabatic Hamiltonian of the quantum-mechanical hydroxyl is diagonalized on-the-fly to obtain the corresponding adiabatic energy levels and wave functions which depend parametrically on the instantaneous configuration of the classical degrees of freedom. The dynamics of the classical degrees of freedom are in turn affected by the quantum-mechanical state of the tagged hydroxyl stretch via the corresponding Hellmann-Feynman forces. The ability of five different force-field combinations to reproduce the experimental absorption infrared spectrum of the hydroxyl stretch is examined for different isotopomers and on a wide range of compositions. It is found that, in addition to accounting for the anharmonic nature of the hydroxyl stretch, one also has to employ polarizable force fields and account for the damping of the polarizability at short distances. The equilibrium ground-state hydrogen-bonding structure and dynamics is analyzed, and its signature on the absorption infrared spectrum of the hydroxyl stretch is investigated in detail. Five different hydroxyl stretch subpopulations are identified and spectrally assigned: monomers (α), hydrogen-bond acceptors (β), hydrogen-bond donors (γ), simultaneous hydrogen-bond donors and acceptors (δ), and simultaneous hydrogen-bond donors and double-acceptors (ε). The fundamental transition frequencies of the α and β subpopulations are found to be narrowly distributed and to overlap, thereby giving rise to a single narrow band whose intensity is significantly diminished by rotational relaxation. The fundamental transition frequency distributions of the γ, δ, and ε subpopulations are found to be

  8. An ATR-FTIR Study on the Effect of Molecular Structural Variations on the CO2 Absorption Characteristics of Heterocyclic Amines, Part II

    PubMed Central

    Robinson, Kelly; McCluskey, Adam; Attalla, Moetaz I

    2012-01-01

    This paper reports on an ATR-FTIR spectroscopic investigation of the CO2 absorption characteristics of a series of heterocyclic diamines: hexahydropyrimidine (HHPY), 2-methyl and 2,2-dimethylhexahydropyrimidine (MHHPY and DMHHPY), hexahydropyridazine (HHPZ), piperazine (PZ) and 2,5- and 2,6-dimethylpiperazine (2,6-DMPZ and 2,5-DMPZ). By using in situ ATR-FTIR the structure–activity relationship of the reaction between heterocyclic diamines and CO2 is probed. PZ forms a hydrolysis-resistant carbamate derivative, while HHPY forms a more labile carbamate species with increased susceptibility to hydrolysis, particularly at higher CO2 loadings (>0.5 mol CO2/mol amine). HHPY exhibits similar reactivity toward CO2 to PZ, but with improved aqueous solubility. The α-methyl-substituted MHHPY favours HCO3− formation, but MHHPY exhibits comparable CO2 absorption capacity to conventional amines MEA and DEA. MHHPY show improved reactivity compared to the conventional α-methyl- substituted primary amine 2-amino-2-methyl-1-propanol. DMHHPY is representative of blended amine systems, and its reactivity highlights the advantages of such systems. HHPZ is relatively unreactive towards CO2. The CO2 absorption capacity CA (mol CO2/mol amine) and initial rates of absorption RIA (mol CO2/mol amine min−1) for each reactive diamine are determined: PZ: CA=0.92, RIA=0.045; 2,6-DMPZ: CA=0.86, RIA=0.025; 2,5-DMPZ: CA=0.88, RIA=0.018; HHPY: CA=0.85, RIA=0.032; MHHPY: CA=0.86, RIA=0.018; DMHHPY: CA=1.1, RIA=0.032; and HHPZ: no reaction. Calculations at the B3LYP/6-31+G** and MP2/6-31+G** calculations show that the substitution patterns of the heterocyclic diamines affect carbamate stability, which influences hydrolysis rates. PMID:22517608

  9. Kinetics absorption characteristics of ferrous glycinate in SD rats and its impact on the relevant transport protein.

    PubMed

    Zhuo, Zhao; Fang, Shenglin; Yue, Min; Zhang, Yiwei; Feng, Jie

    2014-05-01

    Ferrous glycinate (Fe-Gly) maintains high bioavailability in animals, but its exact absorption mechanism is still unknown. Here, we studied on the absorption kinetics of ferrous glycinate and its impact on the relevant transport protein in Sprague-Dawley (SD) rats. A total of 72 SD rats (male, BW 100 ± 6.25 g) were randomly allotted to three treatments. These treatments were perfused with 1 mL of normal saline, ferrous sulfate (FeSO4), and ferrous glycinate (71.35 mg/L as iron) separately. Four rats were selected from each treatment for collection of blood from the tails at certain times (15, 30, 45, 60, 75, 90, 120, 240, and 360 min) after gavage. Moreover, other six rats selected from each treatment were slaughtered for sampling after gavage at 2, 4, and 6 h to evaluate the expression of intestinal transport protein. Pharmacokinetic parameters of iron were determined by one-compartmental analysis. Compared with FeSO4, the peak plasma concentration of iron (C max) is higher in the rats given gavage with Fe-Gly (P < 0.05). Four hours after gavage with Fe-Gly, the expression of divalent metal transporter 1 (DMT1) in the duodenum is significantly decreased (P < 0.05), but the expression of ferroportin 1 (Fpn1) is significantly increased (P < 0.05). This study indicates that Fe-Gly as iron sources can be absorbed more and utilized faster than FeSO4, and they had different effects on the expression of intestinal transport protein.

  10. Characteristics and gel properties of gelatin from goat skin as affected by pretreatments using sodium sulfate and hydrogen peroxide.

    PubMed

    Mad-Ali, Sulaiman; Benjakul, Soottawat; Prodpran, Thummanoon; Maqsood, Sajid

    2016-04-01

    Goat skin can be used as an alternative raw material for gelatin production, in which pretreatment conditions can determine the characteristics or properties of the resulting gelatin. The present study aimed to investigate the effect of pretreatment using sodium sulfate (Na2SO4) and hydrogen peroxide (H2O2) on properties of goat skin gelatin. Pretreatment of skin using Na2SO4 (0-1 mol L(-1)) increased the yield of gelatin in a concentration-dependent manner. When skins with prior Na2SO4 treatment were bleached using H2O2 (0-2 mol L(-1)), the resulting gelatin showed higher yield and gel strength than those without prior Na2SO4 treatment. All gelatins had α-chain as a major component, followed by β-chain. The degradation induced by H2O2 was lower in gelatin with prior Na2SO4 treatment. L* values increased with increasing H2O2 concentrations (P < 0.05) due to the bleaching effect of H2O2. With Na2SO4 and H2O2 pretreatments, gelatin gel had a finer and more ordered microstructure. Gelatin had an imino acid content of 217 residues/1000 residues with gelling and melting temperature of 22.49 and 32.28 °C, respectively. The optimal pretreatment conditions for gelatin extraction from goat skin included soaking the skin in 0.75 mol L(-1) NaOH, followed by treatment using 0.75 mol L(-1) Na2SO4 and subsequent bleaching with 2 mol L(-1) H2O2. This resulted in gelatin with superior quality to the untreated counterpart. © 2015 Society of Chemical Industry.

  11. Hydrogen Passivation of Interstitial Zn Defects in Heteroepitaxial InP Cell Structures and Influence on Device Characteristics

    NASA Technical Reports Server (NTRS)

    Ringel, S. A.; Chatterjee, B.

    2004-01-01

    Hydrogen passivation of heteroepitaxial InP solar cells is of recent interest for deactivation of dislocations and other defects caused by the cell/substrate lattice mismatch that currently limit the photovoltaic performance of these devices. In this paper we present strong evidence that, in addition to direct hydrogen-dislocation interactions, hydrogen forms complexes with the high concentration of interstitial Zn defects present within the p(+) Zn-doped emitter of MOCVD-grown heteroepitaxial InP devices, resulting in a dramatic increase of the forward bias turn-on voltage by as much as 280 mV, from 680 mV to 960 mV. This shift is reproducible and thermally reversible and no such effect is observed for either n(+)p structures or homoepitaxial p(+)n structures grown under identical conditions. A combination of photoluminescence (PL), electrochemical C-V dopant profiling, SIMS and I-V measurements were performed on a set of samples having undergone a matrix of hydrogenation and post-hydrogenation annealing conditions to investigate the source of this voltage enhancement and confirm the expected role of interstitial Zn and hydrogen. A precise correlation between all measurements is demonstrated which indicates that Zn interstitials within the p(+) emitter and their interaction with hydrogen are indeed responsible for this device behavior.

  12. Study on the influence of the response characteristics of a temperature sensor on the measurement accuracy of a water-absorption-based high-energy laser energy meter

    NASA Astrophysics Data System (ADS)

    Wei, Ji Feng; Sun, Li Qun; Zhang, Kai

    2013-05-01

    When using water as a cooling or absorption medium for an energy meter, a temperature sensor is limited by response characteristics and cannot reflect the real-time temperature changes in the water flow. In order to improve the accuracy of measurement, we should ensure that the corresponding value of the temperature integral will be substantially independent of the effects of the sensor response time. According to the analysis of the interaction process between temperature sensor and water flow temperature field, we have established a hot physical model of the whole measurement process, and decomposed it into a superposition of a slowly varying process and a transient process, then simplified the model. Finally, a quantitative relationship between the sensor response characteristics and measurement accuracy of the high energy laser energy meter is derived. With the mandatory heat exchange method, the frequency characteristics of the temperature field meet the requirements of the frequency characteristics of a temperature sensor; as a result, the impact on measurement accuracy is eliminated. The experimental results show that this method has good effects, and it can help to improve the measurement accuracy of a high-energy laser energy meter.

  13. Optical absorption characteristics in the assessment of powder phosphor-based x-ray detectors: from nano- to micro-scale.

    PubMed

    Liaparinos, P F

    2015-11-21

    X-ray phosphor-based detectors have enormously improved the quality of medical imaging examinations through the optimization of optical diffusion. In recent years, with the development of science and technology in the field of materials, improved powder phosphors require structural and optical properties that contribute to better optical signal propagation. The purpose of this paper was to provide a quantitative and qualitative understanding of the optical absorption characteristics in the assessment of powder phosphor-based detectors (from nano- scale up to micro-scale). Variations on the optical absorption parameters (i.e. the light extinction coefficient [Formula: see text] and the percentage probability of light absorption p%) were evaluated based on Mie calculations examining a wide range of light wavelengths, particle refractive indices and sizes. To model and assess the effects of the aforementioned parameters on optical diffusion, Monte Carlo simulation techniques were employed considering: (i) phosphors of different layer thickness, 100 μm (thin layer) and 300 μm (thick layer), respectively, (ii) light extinction coefficient values, 1, 3 and 6 μm(-1), and (iii) percentage probability of light absorption p% in the range 10(-4)-10(-2). Results showed that the [Formula: see text] coefficient is high for phosphor grains in the submicron scale and for low light wavelengths. At higher wavelengths (above 650 nm), optical quanta follow approximately similar depths until interaction for grain diameter 500 nm and 1 μm. Regarding the variability of the refractive index, high variations of the [Formula: see text] coefficient occurred above 1.6. Furthermore, results derived from Monte Carlo modeling showed that high spatial resolution phosphors can be accomplished by increasing the [Formula: see text] parameter. More specifically, the FWHM was found to decrease (i.e. higher resolution): (i) 4.8% at 100 μm and (ii) 9.5%, at 300 μm layer thickness. This study

  14. Optical absorption characteristics in the assessment of powder phosphor-based x-ray detectors: from nano- to micro-scale

    NASA Astrophysics Data System (ADS)

    Liaparinos, P. F.

    2015-11-01

    X-ray phosphor-based detectors have enormously improved the quality of medical imaging examinations through the optimization of optical diffusion. In recent years, with the development of science and technology in the field of materials, improved powder phosphors require structural and optical properties that contribute to better optical signal propagation. The purpose of this paper was to provide a quantitative and qualitative understanding of the optical absorption characteristics in the assessment of powder phosphor-based detectors (from nano- scale up to micro-scale). Variations on the optical absorption parameters (i.e. the light extinction coefficient {{m}\\text{ext}} and the percentage probability of light absorption p%) were evaluated based on Mie calculations examining a wide range of light wavelengths, particle refractive indices and sizes. To model and assess the effects of the aforementioned parameters on optical diffusion, Monte Carlo simulation techniques were employed considering: (i) phosphors of different layer thickness, 100 μm (thin layer) and 300 μm (thick layer), respectively, (ii) light extinction coefficient values, 1, 3 and 6 μm-1, and (iii) percentage probability of light absorption p% in the range 10-4-10-2. Results showed that the {{m}\\text{ext}} coefficient is high for phosphor grains in the submicron scale and for low light wavelengths. At higher wavelengths (above 650 nm), optical quanta follow approximately similar depths until interaction for grain diameter 500 nm and 1 μm. Regarding the variability of the refractive index, high variations of the {{m}\\text{ext}} coefficient occurred above 1.6. Furthermore, results derived from Monte Carlo modeling showed that high spatial resolution phosphors can be accomplished by increasing the {{m}\\text{ext}} parameter. More specifically, the FWHM was found to decrease (i.e. higher resolution): (i) 4.8% at 100 μm and (ii) 9.5%, at 300 μm layer thickness. This study attempted to

  15. Characteristics of a tapered undulator for the X-ray absorption fine-structure technique at PLS-II.

    PubMed

    Sung, Nark-Eon; Lee, Ik-Jae; Jeong, Sung-hoon; Kang, Seen-Woong

    2014-11-01

    An in-vacuum undulator (IVU) with a tapered configuration was installed in the 8C nanoprobe/XAFS beamlime (BL8C) of the Pohang Light Source in Korea for hard X-ray nanoprobe and X-ray absorption fine-structure (XAFS) experiments. It has been operated in planar mode for the nanoprobe experiments, while gap-scan and tapered modes have been used alternatively for XAFS experiments. To examine the features of the BL8C IVU for XAFS experiments, spectral distributions were obtained theoretically and experimentally as functions of the gap and gap taper. Beam profiles at a cross section of the X-ray beam were acquired using a slit to visualize the intensity distributions which depend on the gap, degree of tapering and harmonic energies. To demonstrate the effect of tapering around the lower limit of the third-harmonic energy, V K-edge XAFS spectra were obtained in each mode. Owing to the large X-ray intensity variation around this energy, XAFS spectra of the planar and gap-scan modes show considerable spectral distortions in comparison with the tapered mode. This indicates that the tapered mode, owing to the smooth X-ray intensity profile at the expense of the highest and most stable intensity, can be an alternative for XAFS experiments where the gap-scan mode gives a considerable intensity variation; it is also suitable for quick-XAFS scanning.

  16. Statistical analysis of whole-body absorption depending on anatomical human characteristics at a frequency of 2.1 GHz

    NASA Astrophysics Data System (ADS)

    El Habachi, A.; Conil, E.; Hadjem, A.; Vazquez, E.; Wong, M. F.; Gati, A.; Fleury, G.; Wiart, J.

    2010-04-01

    In this paper, we propose identification of the morphological factors that may impact the whole-body averaged specific absorption rate (WBSAR). This study is conducted for the case of exposure to a front plane wave at a 2100 MHz frequency carrier. This study is based on the development of different regression models for estimating the WBSAR as a function of morphological factors. For this purpose, a database of 12 anatomical human models (phantoms) has been considered. Also, 18 supplementary phantoms obtained using the morphing technique were generated to build the required relation. This paper presents three models based on external morphological factors such as the body surface area, the body mass index or the body mass. These models show good results in estimating the WBSAR (<10%) for families obtained by the morphing technique, but these are still less accurate (30%) when applied to different original phantoms. This study stresses the importance of the internal morphological factors such as muscle and fat proportions in characterization of the WBSAR. The regression models are then improved using internal morphological factors with an estimation error of approximately 10% on the WBSAR. Finally, this study is suitable for establishing the statistical distribution of the WBSAR for a given population characterized by its morphology.

  17. Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

    2009-12-01

    We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

  18. Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy

    SciTech Connect

    Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

    2010-05-01

    We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

  19. Evaluation of in vitro release rate and in vivo absorption characteristics of four metoprolol tartrate immediate-release tablet formulations.

    PubMed

    Rekhi, G S; Eddington, N D; Fossler, M J; Schwartz, P; Lesko, L J; Augsburger, L L

    1997-02-01

    The purpose of this investigation was to examine the impact of formulation and process changes on dissolution and bioavailability/bioequivalency of metoprolol tartrate tablets manufactured using a high-shear granulation process. A half-factorial (2(4-1), Res IV) design was undertaken to study the selected formulation and processing variables during scale-up. Levels and ranges for excipients and processing changes studied represented level 2 or greater changes as indicated by the SUPAC-IR Guidance. Blend and tableting properties were evaluated. Changes in sodium starch glycolate and magnesium stearate levels, and the order of addition microcrystalline cellulose (intra- vs. extragranular) were significant only in affecting percent drug released (Q) in 5, 10, and 15 min. Statistical analysis of data showed no significant curvature. No interaction effects were found to be statistically significant. To examine the impact of formulation and processing variables on in vivo absorption, three batches were selected for a bioavailability study based on their dissolution profiles. Subjects received four metoprolol treatments (Lopressor, slow-, medium-, and fast-dissolving formulations) separated by 1 week according to a randomized crossover design. After an overnight fast, subjects were administered one tablet (100 mg), blood samples were collected over 24 hr and plasma samples were analyzed. The formulations were found to be bioequivalent with respect to the log Cmax and log AUC0-infinity. The results of this study suggest that: (i) bioavailability/bioequivalency studies may not be necessary for metoprolol tartrate and perhaps other class 1 drugs after level 2 type changes and (ii) in vitro dissolution tests may be used to show bioequivalence of metoprolol formulations with processing or formulation changes within the specified level 2 ranges for the equipment examined.

  20. Ultrafine hydrogen storage powders

    DOEpatents

    Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

    2000-06-13

    A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

  1. Surface Modification of Poly(methyl methacrylate) by Hydrogen-Plasma Exposure and Its Sputtering Characteristics by Ultraviolet Light Irradiation

    NASA Astrophysics Data System (ADS)

    Yoshimura, Satoru; Ikuse, Kazumasa; Sugimoto, Satoshi; Murai, Kensuke; Honjo, Kuniaki; Kiuchi, Masato; Hamaguchi, Satoshi

    2013-09-01

    Surface modification of poly(methyl methacrylate) (PMMA) films by hydrogen-plasma exposure has been studied in the light of sputtering resistance of polymer-based materials in plasma etching processes. Surface measurements of PMMA were performed with X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and spectroscopic ellipsometry. It has been found that oxygen atoms are preferentially removed from the surface when a PMMA film is subjected to hydrogen-plasma exposure, with the depth of modification being about 40 nm in the case we examined. Hydrogen-plasma exposure is also found to reduce the sputtering yields of PMMA by ultraviolet light irradiation, as in the case of Ar+ ion irradiation [S. Yoshimura et al.: J. Vac. Soc. Jpn. 56 (2013) 129]. The results suggest that PMMA films become hardened and more sputtering resistant due to the formation of a thick (i.e., 40 nm in the case of this study) amorphous carbon layer by hydrogen-plasma exposure. Hydrogen-plasma exposure is thus an effective technique to increase etching resistance of polymer films.

  2. Absorption and fluorescence characteristics of photo-activated adenylate cyclase nano-clusters from the amoeboflagellate Naegleria gruberi NEG-M strain

    NASA Astrophysics Data System (ADS)

    Penzkofer, A.; Stierl, M.; Hegemann, P.; Kateriya, S.

    2012-01-01

    The spectroscopic characteristics of BLUF (BLUF = sensor of blue light using flavin) domain containing soluble adenylate cyclase (nPAC = Naegleria photo-activated cyclase) samples from the amoeboflagellate Naegleria gruberi NEG-M strain is studied at room temperature. The absorption and fluorescence spectroscopic development in the dark was investigated over two weeks. Attenuation coefficient spectra, fluorescence quantum distributions, fluorescence quantum yields, and fluorescence excitation distributions were measured. Thawing of frozen nPAC samples gave solutions with varying protein nano-cluster size and varying flavin, tyrosine, tryptophan, and protein color-center emission. Protein color-center emission was observed in the wavelength range of 360-900 nm with narrow emission bands of small Stokes shift and broad emission bands of large Stokes shift. The emission spectra evolved in time with protein nano-cluster aging.

  3. Variation in the EPR characteristics of nanosized zirconia particles under exposure to X-ray radiation and annealing in hydrogen

    NASA Astrophysics Data System (ADS)

    Bykov, I. P.; Brik, A. B.; Glinchuk, M. D.; Bevz, V. V.; Kalinichenko, E. A.; Konstantinova, T. E.; Danilenko, I. A.

    2008-12-01

    The effects of various external factors on the properties of nanosized zirconia particles are studied using electron paramagnetic resonance. It is shown that x-rays initiate radiation-stimulated oxidation of chromium impurity ions according to the scheme Cr3+ → Cr5+. Annealing of samples in hydrogen at temperatures in the range 250-650°C brings about a substantial decrease in the fraction of chromium ions in the Cr5+ charge state, but subsequent annealing of these samples in air leads to an increase in the Cr5+ fraction. Samples annealed in hydrogen generate a singlet EPR signal with the g factor of 2.0033 ± 0.0005 originating from electrically conducting regions which are formed on the surface of zirconia nanoparticles during their annealing in hydrogen.

  4. Enhancement of optical absorption in silicon thin-film solar cells with metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Shi, Bo; Wang, Wei; Yu, Xueqing; Yang, Lili; Xu, Yuanpei

    2017-05-01

    Light trapping structures are a promising method of improving the efficiency of solar cells. We focused on the plasmonic thin-film solar cell. A structure is proposed consisting of an indium tin oxide layer with embedded metal nanoparticles, a hydrogenated amorphous silicon (a-Si:H) layer, and an aluminum (Al) layer. The finite-difference-time-domain (FDTD) method was used to calculate the absorption characteristics of the a-Si:H thin-film solar cells containing nanoparticles. By arranging the material, size, and locations of metal nanoparticles to maximize the scattering and minimize absorption of nanoparticles themselves, the optical absorption in the solar cell is significantly enhanced.

  5. Threshold switching behavior of Ag-Si based selector device and hydrogen doping effect on its characteristics

    SciTech Connect

    Yoo, Jongmyung; Woo, Jiyong; Song, Jeonghwan; Hwang, Hyunsang

    2015-12-15

    The effect of hydrogen treatment on the threshold switching property in a Ag/amorphous Si based programmable metallization cells was investigated for selector device applications. Using the Ag filament formed during motion of Ag ions, a steep-slope (5 mV/dec.) for threshold switching with higher selectivity (∼10{sup 5}) could be achieved. Because of the faster diffusivity of Ag atoms, which are inside solid-electrolytes, the resulting Ag filament could easily be dissolved under low current regime, where the Ag filament possesses weak stability. We found that the dissolution process could be further enhanced by hydrogen treatment that facilitated the movement of the Ag atoms.

  6. Characteristics of a high-power RF source of negative hydrogen ions for neutral beam injection into controlled fusion devices

    NASA Astrophysics Data System (ADS)

    Abdrashitov, G. F.; Belchenko, Yu. I.; Gusev, I. A.; Ivanov, A. A.; Kondakov, A. A.; Sanin, A. L.; Sotnikov, O. Z.; Shikhovtsev, I. V.

    2017-01-01

    An injector of hydrogen atoms with an energy of 0.5-1 MeV and equivalent current of up to 1.5 A for purposes of controlled fusion research is currently under design at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. Within this project, a multiple-aperture RF surface-plasma source of negative hydrogen ions is designed. The source design and results of experiments on the generation of a negative ion beam with a current of >1 A in the long-pulse mode are presented.

  7. Characteristics of 1.9 μm laser emission from hydrogen-filled hollow-core fiber by stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Gu, Bo; Chen, Yubin; Wang, Zefeng

    2016-11-01

    We report here the detailed characteristics of 1.9 μm laser emission from hydrogen-filled hollow-core fiber by stimulated Raman scattering. A 6.5 m hydrogen-filled Ice-cream negative curvature hollow-core fiber is pumped with a high peak power, narrow linewidth, liner polarized subnanosecond pulsed 1064 nm microchip laser, generating pulsed 1908.5 nm vibrational Stokes wave. The linewidth of the pump laser and the vibrational Stokes wave is about 1 GHz and 2 GHz respectively. And the maximum Raman conversion quantum efficiency is about 48%. We also studied the pulse shapes of the pump laser and the vibrational Stokes wave. The polarization dependence of the vibrational and the rotational stimulated Raman scattering is also investigated. In addition, the beam profile of vibrational Stokes wave shows good quality, which may be taken advantage of in many applications.

  8. Simultaneous measurement of nitrogen and hydrogen dissociation from vacuum ultraviolet self-absorption spectroscopy in a developing low temperature plasma at atmospheric pressure

    SciTech Connect

    Laity, George; Fierro, Andrew; Dickens, James; Neuber, Andreas; Frank, Klaus

    2013-05-06

    We demonstrate a method for determining the dissociation density of N and H atoms present in a developing low temperature plasma, based on the emission and self-absorption of vacuum ultraviolet radiation produced from the plasma. Spark plasmas are produced via pulsed discharge in N{sub 2}/H{sub 2} mixtures at atmospheric pressure, where information on the dissociated densities of the constituent gas molecules is desired without employing invasive diagnostic techniques. By analyzing the self-absorption line profile of 121.5 nm Lyman-{alpha} H radiation emitted within the first {approx}1.0 mm of plasma near the anode tip, a peak dissociated H atom concentration of 5.6 Multiplication-Sign 10{sup 17} cm{sup -3} was observed {approx}100 ns into spark formation, with an estimated electron density of 2.65 Multiplication-Sign 10{sup 18} cm{sup -3} determined from Stark broadening. Similarly, simultaneous line fitting of the N 120.0/124.3 nm emission profiles revealed a peak dissociated N atom concentration of 3.8 Multiplication-Sign 10{sup 17} cm{sup -3} during the same discharge period.

  9. Influence of hydrogen oxidation kinetics on hydrogen environment embrittlement

    NASA Technical Reports Server (NTRS)

    Walter, R. J.; Kendig, M. W.; Meisels, A. P.

    1992-01-01

    Results are presented from experiments performed to determine the roles of hydrogen absorption and hydrogen electron transfer on the susceptibility of Fe- and Ni-base alloys to ambient-temperature hydroen embrittlement. An apparent independence is noted between hydrogen environment embrittlement and internal hydrogen embrittlement. The experiments were performed on Inconel 718, Incoloy 903, and A286. The electrochemical results obtained indicate that Inconel 718 either adsorbs hydrogen more rapidly and/or the electrochemical oxidation of the adsorbed hydrogen occurred more rapidly than in the other two materials.

  10. Characteristics of hydrogen and methane production from cornstalks by an augmented two- or three-stage anaerobic fermentation process.

    PubMed

    Lu, Yuan; Lai, Qiheng; Zhang, Chong; Zhao, Hongxin; Ma, Kun; Zhao, Xuebing; Chen, Hongzhang; Liu, Dehua; Xing, Xin-Hui

    2009-06-01

    This paper presents the co-production of hydrogen and methane from cornstalks by a two- or three-stage anaerobic fermentation process augmented with effective artificial microbial community. Two-stage fermentation by using the anaerobic sludge and DGGE analysis showed that effective and stable strains should be introduced into the system. We introduced Enterobacter aerogens or Clostridium paraputrificum into the hydrogen stage, and C. paraputrificum was proven to be more effective. In the three-stage process consisting of the improved hydrolysis, hydrogen and methane production stages, the highest soluble sugars (0.482 kg/kg cornstalks) were obtained after the introduction of Clostridium thermocellum in the hydrolysis stage, under the thermophilic (55 degrees C) and acidic (pH 5.0) conditions. Hydrolysates from 1 kg of cornstalks could produce 2.61 mol (63.7 l) hydrogen by augmentation with C. paraputrificum and 4.69 mol (114.6 l) methane by anaerobic granular sludge, corresponding to 54.1% energy recovery.

  11. Optical studies of solid hydrogen to 320 GPa and evidence for black hydrogen.

    PubMed

    Loubeyre, Paul; Occelli, Florent; LeToullec, René

    2002-04-11

    The quest for metallic hydrogen at high pressures represents a longstanding problem in condensed matter physics. Recent calculations have predicted that solid hydrogen should become a molecular metal at pressures above 300 GPa, before transforming into an alkali metal; but the strong quantum nature of the problem makes the predictions difficult. Over a decade ago, an optical study of hydrogen was made using a diamond anvil cell to reach 250 GPa. However, despite many subsequent efforts, quantitative studies at higher pressures have proved difficult and their conclusions controversial. Here we report optical measurements of solid hydrogen up to a pressure of 320 GPa at 100 K. The vibron signature of the H2 molecule persists to at least 316 GPa; no structural changes are detected above 160 GPa, and solid hydrogen is observed to turn completely opaque at 320 GPa. We measure the absorption edge of hydrogen above 300 GPa, observing features characteristic of a direct electronic bandgap. This is at odds with the most recent theoretical calculations that predict much larger direct transition energies and the closure of an indirect gap. We predict that metal hydrogen should be observed at about 450 GPa when the direct gap closes.

  12. Performance and characteristics of a high pressure, high temperature capillary cell with facile construction for operando x-ray absorption spectroscopy

    SciTech Connect

    Bansode, Atul; Urakawa, Atsushi; Guilera, Gemma; Simonelli, Laura; Avila, Marta; Cuartero, Vera

    2014-08-15

    We demonstrate the use of commercially available fused silica capillary and fittings to construct a cell for operando X-ray absorption spectroscopy (XAS) for the study of heterogeneously catalyzed reactions under high pressure (up to 200 bars) and high temperature (up to 280 °C) conditions. As the first demonstration, the cell was used for CO{sub 2} hydrogenation reaction to examine the state of copper in a conventional Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst. The active copper component of the catalyst was shown to remain in the metallic state under supercritical reaction conditions, at 200 bars and up to 260 °C. With the coiled heating system around the capillary, one can easily change the length of the capillary and control the amount of catalyst under investigation. With precise control of reactant(s) flow, the cell can mimic and serve as a conventional fixed-bed micro-reactor system to obtain reliable catalytic data. This high comparability of the reaction performance of the cell and laboratory reactors is crucial to gain insights into the nature of actual active sites under technologically relevant reaction conditions. The large length of the capillary can cause its bending upon heating when it is only fixed at both ends because of the thermal expansion. The degree of the bending can vary depending on the heating mode, and solutions to this problem are also presented. Furthermore, the cell is suitable for Raman studies, nowadays available at several beamlines for combined measurements. A concise study of CO{sub 2} phase behavior by Raman spectroscopy is presented to demonstrate a potential of the cell for combined XAS-Raman studies.

  13. Performance and characteristics of a high pressure, high temperature capillary cell with facile construction for operando x-ray absorption spectroscopy.

    PubMed

    Bansode, Atul; Guilera, Gemma; Cuartero, Vera; Simonelli, Laura; Avila, Marta; Urakawa, Atsushi

    2014-08-01

    We demonstrate the use of commercially available fused silica capillary and fittings to construct a cell for operando X-ray absorption spectroscopy (XAS) for the study of heterogeneously catalyzed reactions under high pressure (up to 200 bars) and high temperature (up to 280 °C) conditions. As the first demonstration, the cell was used for CO2 hydrogenation reaction to examine the state of copper in a conventional Cu/ZnO/Al2O3 methanol synthesis catalyst. The active copper component of the catalyst was shown to remain in the metallic state under supercritical reaction conditions, at 200 bars and up to 260 °C. With the coiled heating system around the capillary, one can easily change the length of the capillary and control the amount of catalyst under investigation. With precise control of reactant(s) flow, the cell can mimic and serve as a conventional fixed-bed micro-reactor system to obtain reliable catalytic data. This high comparability of the reaction performance of the cell and laboratory reactors is crucial to gain insights into the nature of actual active sites under technologically relevant reaction conditions. The large length of the capillary can cause its bending upon heating when it is only fixed at both ends because of the thermal expansion. The degree of the bending can vary depending on the heating mode, and solutions to this problem are also presented. Furthermore, the cell is suitable for Raman studies, nowadays available at several beamlines for combined measurements. A concise study of CO2 phase behavior by Raman spectroscopy is presented to demonstrate a potential of the cell for combined XAS-Raman studies.

  14. [Characteristics of absorption and fluorescence spectra of dissolved organic matter from confluence of rivers: case study of Qujiang River-Jialing River and Fujiang River-Jialing River].

    PubMed

    Yan, Jin-Long; Jiang, Tao; Gao, Jie; Wei, Shi-Qiang; Lu, Song; Liu, Jiang

    2015-03-01

    Three-dimensional fluorescence spectroscopy combined with ultraviolet-visible (UV-Vis) absorption spectra was used to investigate the change characteristics of dissolved organic matter (DOM) in confluences water of Qujiang River-Jialing River and Fujiang River-Jialing River, respectively. The results suggested that DOM showed a significant terrestrial input signal in all the sampling sites, FI < 1.4, HIX > 0.8, possibly representing remarkable signals of humus resulted from humic-like component. Moreover, the mixing zone of this study showed a non-conservative mixed behavior, which had a limited contribution, and was not the dominant factor to interpret the change characteristics of DOM in confluences zones. Different land-use types along all the rivers had an obvious impact on DOM inputs. Results of cluster analysis showed that a higher degree of aromaticity and humification components was observed as the predominant contributor to DOM when the land-use type was forest and farmland ecosystem, for example the confluences of Qujiang River-Jialing River. On the other hand, high concentrations of DOM with relative simple structures were found in the water when the urban land-use type was predominant, for example the confluences of Fujiang River-Jialing River. Meanwhile, a new fluorescent signal of protein-like components (peak T) appeared, which manifested a significant effect on the water quality resulted from anthropogenic activities.

  15. Hydrogen-Mediated Electron Doping of Gold Clusters As Revealed by In Situ X-ray and UV-vis Absorption Spectroscopy.

    PubMed

    Ishida, Ryo; Hayashi, Shun; Yamazoe, Seiji; Kato, Kazuo; Tsukuda, Tatsuya

    2017-06-01

    We previously reported that small (∼1.2 nm) gold clusters stabilized by poly(N-vinyl-2-pyrrolidone) (Au:PVP) exhibited a localized surface plasmon resonance (LSPR) band at ∼520 nm in the presence of NaBH4. To reveal the mechanism of this phenomenon, the electronic structure of Au:PVP during the reaction with NaBH4 in air was examined by means of in situ X-ray absorption spectroscopy at Au L3-edge and UV-vis spectroscopy. These measurements indicated that the appearance of the LSPR band is not associated with the growth in size but is ascribed to electron doping to the Au sp band by the adsorbed H atoms.

  16. Heterojunction of Zinc Blende/Wurtzite in Zn1-xCdxS Solid Solution for Efficient Solar Hydrogen Generation: X-ray Absorption/Diffraction Approaches.

    PubMed

    Hsu, Ying-Ya; Suen, Nian-Tzu; Chang, Chung-Chieh; Hung, Sung-Fu; Chen, Chi-Liang; Chan, Ting-Shan; Dong, Chung-Li; Chan, Chih-Chieh; Chen, San-Yuan; Chen, Hao Ming

    2015-10-14

    In the past decade, inorganic semiconductors have been successfully demonstrated as light absorbers in efficient solar water splitting to generate chemical fuels. Pseudobinary semiconductors Zn1-xCdxS (0≤x≤1) have exhibited a superior photocatalytic reactivity of H2 production from splitting of water by artificial solar irradiation without any metal catalysts. However, most studies had revealed that the extremely high efficiency with an optimal content of Zn1-xCdxS solid solution was determined as a result of elevating the conduction band minimum (CBM) and the width of bandgap. In addition to corresponding band structure and bandgap, the local crystal structure should be taken into account as well to determine its photocatalytic performance. Herein, we demonstrated the correlations between the photocatalytic activity and structural properties that were first studied through synchrotron X-ray diffraction and X-ray absorption spectroscopy. The crystal structure transformed from zinc blende to coexisted phases of major zinc blende and minor wurtzite phases at a critical point. The heterojunction formed by coexistence of zinc blende and wurtzite phases in the Zn1-xCdxS solid solution can significantly improve the separation and migration of photoinduced electron-hole pairs. Besides, X-ray absorption spectra and UV-vis spectra revealed that the bandgap of the Zn0.45Cd0.55S sample extended into the region of visible light because of the incorporation of Cd element in the sample. These results provided a significant progress toward the realization of the photoelectrochemical mechanism in heterojunction between zinc blende and wurtzite phases, which can effectively separate the charge-carriers and further suppress their recombination to enhance the photocatalytic reactivity.

  17. A census of molecular hydrogen outflows and their sources along the Orion A molecular ridge. Characteristics and overall distribution

    NASA Astrophysics Data System (ADS)

    Davis, C. J.; Froebrich, D.; Stanke, T.; Megeath, S. T.; Kumar, M. S. N.; Adamson, A.; Eislöffel, J.; Gredel, R.; Khanzadyan, T.; Lucas, P.; Smith, M. D.; Varricatt, W. P.

    2009-03-01

    Aims: A census of molecular hydrogen flows across the entire Orion A giant molecular cloud is sought. With this paper we aim to associate each flow with its progenitor and associated molecular core, so that the characteristics of the outflows and outflow sources can be established. Methods: We present wide-field near-infrared images of Orion A, obtained with the Wide Field Camera, WFCAM, on the United Kingdom Infrared Telescope. Broad-band K and narrow-band H2 1-0S(1) images of a contiguous ~8 square degree region are compared to mid-IR photometry from the Spitzer Space Telescope and (sub)millimetre dust-continuum maps obtained with the MAMBO and SCUBA bolometer arrays. Using previously-published H2 images, we also measured proper motions for H2 features in 33 outflows, and use these data to help associate flows with existing sources and/or dust cores. Results: Together these data give a detailed picture of dynamical star formation across this extensive region. We increase the number of known H2 outflows to 116. A total of 111 H2 flows were observed with Spitzer; outflow sources are identified for 72 of them (12 more H2 flows have tentative progenitors). The MAMBO 1200 μm maps cover 97 H2 flows; 57 of them (59%) are associated with Spitzer sources and either dust cores or extended 1200 μm emission. The H2 jets are widely distributed and randomly orientated. The jets do not appear to be orthogonal to large-scale filaments or even to the small-scale cores associated with the outflow sources (at least when traced with the 11´´ resolution of the 1200 μm MAMBO observations). Moreover, H2 jet lengths (L) and opening angles (θ) are not obviously correlated with indicators of outflow source age - source spectral index, α (measured from mid-IR photometry), or (sub)millimetre core flux. It seems clear that excitation requirements limit the usefulness of H2 as a tracer of L and θ (though jet position angles are well defined). Conclusions: We demonstrate that H2 jet

  18. Testing for hydrogen environment embrittlement - Experimental variables

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1974-01-01

    Hydrogen embrittlement is classified into three types: internal reversible hydrogen embrittlement, hydrogen reaction embrittlement, and hydrogen environment embrittlement. Characteristics of and materials embrittled by these types of hydrogen embrittlement are discussed. Hydrogen environment embrittlement is reviewed in detail. Factors involved in standardizing test methods for detecting the occurrence of and evaluating the severity of hydrogen environment embrittlement are considered. The effects of test technique, hydrogen pressure, gas purity, strain rate, stress concentration factor, and test temperature are discussed.

  19. Linear and Nonlinear Optical Properties of Photoresponsive [60]Fullerene Hybrid Triads and Tetrads with Dual NIR Two-Photon Absorption Characteristics

    PubMed Central

    Jeon, Seaho; Haley, Joy; Flikkema, Jonathan; Nalla, Venkatram; Wang, Min; Sfeir, Matthew; Tan, Loon-Seng; Cooper, Thomas; Ji, Wei; Hamblin, Michael R.; Chiang, Long Y.

    2013-01-01

    Two C60-(antenna)x analogous compounds having branched hybrid triad C60(>DPAF-C18)(>CPAF-C2M) and tetrad C60(>DPAF-C18)(>CPAF-C2M)2 nanostructures were synthesized and characterized. The structural design was intended to facilitate the ultrafast fs intramolecular energy-transfer from photoexcited C60[>1(DPAF)*-C18](>CPAF-C2M)1or2 or C60(>DPAF-C18)[>1(CPAF)*-C2M]1or2 to the C60> cage moiety upon two-photon pumping at either 780 or 980 nm, respectively. The latter nanostructure showed approximately equal extinction coefficients of optical absorption over 400–550 nm that corresponds to near-IR two-photon based excitation wavelengths at 780–1100 nm for broadband nonlinear optical (NLO) applications. Aside from their enhanced two-photon absorption (2PA) activity at 780 nm, we also demonstrated ultrafast photo-responses at 980 nm showing 2PA cross-section (σ2) values of 995–1100 GM for the hybrid tetrad. These σ2 values were correlated to the observed good efficiency in reducing fs light-transmittance down to 35% at the light intensity of 110 GW/cm2. Accordingly, 2PA characteristics of these nanostructures at multiple NIR wavelengths provided support for their suitability in uses as broadband NLO nanomaterials at 600–1100 nm that includes the 2PA ability of two antenna, DPAF (700–850 nm) and CPAF (850–1100 nm), and the fullerene cage at shorter wavelengths (600–700 nm). PMID:24163713

  20. Comparison of Chemical and Enzymatic Interesterification of Fully Hydrogenated Soybean Oil and Walnut Oil to Produce a Fat Base with Adequate Nutritional and Physical Characteristics

    PubMed Central

    Farfán, Mariel; Álvarez, Alfredo; Gárate, Alan

    2015-01-01

    Summary The optimal physical, chemical and nutritional properties of natural lipids depend on the structure and composition of triacylglycerols. However, they are not always mutually compatible. Lipid modification is a good way to give them specific functionalities, increase their oxidative stability, or improve their nutritional value. As such, chemical and enzymatic interesterification may be used to modify them and produce structured lipids. In accordance, the aim of this study is to compare chemical and enzymatic interesterification of binary blends of fully hydrogenated soybean oil and walnut oil, using sodium methoxide or Lipozyme TL IM, respectively, to produce a fat base with adequate nutritional and physical characteristics. Three different mass ratios of fully hydrogenated soybean oil and walnut oil blends (20:80, 40:60 and 60:40) were interesterified and evaluated. Total interesterification was determined by the stabilization of the solid fat content. Chemical reaction of the 20:80 blend was completed in 10 min and of the 40:60 and 60:40 blends in 15 min. Enzymatically interesterified blends were stabilized in 120 min at all of the mass ratios. Complete interesterification significantly reduced the solid fat content of the blends at any composition. Chemical and enzymatically interesterified fully hydrogenated blend of soybean and walnut oil at mass ratio of 40:60 showed the plastic curve of an all-purpose- -type shortening rich in polyunsaturated fatty acids, with a high linolenic acid (C18:3n3) content and with zero trans-fatty acids. PMID:27904370

  1. Comparison of Chemical and Enzymatic Interesterification of Fully Hydrogenated Soybean Oil and Walnut Oil to Produce a Fat Base with Adequate Nutritional and Physical Characteristics.

    PubMed

    Farfán, Mariel; Álvarez, Alfredo; Gárate, Alan; Bouchon, Pedro

    2015-09-01

    The optimal physical, chemical and nutritional properties of natural lipids depend on the structure and composition of triacylglycerols. However, they are not always mutually compatible. Lipid modification is a good way to give them specific functionalities, increase their oxidative stability, or improve their nutritional value. As such, chemical and enzymatic interesterification may be used to modify them and produce structured lipids. In accordance, the aim of this study is to compare chemical and enzymatic interesterification of binary blends of fully hydrogenated soybean oil and walnut oil, using sodium methoxide or Lipozyme TL IM, respectively, to produce a fat base with adequate nutritional and physical characteristics. Three different mass ratios of fully hydrogenated soybean oil and walnut oil blends (20:80, 40:60 and 60:40) were interesterified and evaluated. Total interesterification was determined by the stabilization of the solid fat content. Chemical reaction of the 20:80 blend was completed in 10 min and of the 40:60 and 60:40 blends in 15 min. Enzymatically interesterified blends were stabilized in 120 min at all of the mass ratios. Complete interesterification significantly reduced the solid fat content of the blends at any composition. Chemical and enzymatically interesterified fully hydrogenated blend of soybean and walnut oil at mass ratio of 40:60 showed the plastic curve of an all-purpose- -type shortening rich in polyunsaturated fatty acids, with a high linolenic acid (C18:3n3) content and with zero trans-fatty acids.

  2. Hydrogen storage properties of lithium silicon alloy synthesized by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Doi, Koichi; Hino, Satoshi; Miyaoka, Hiroki; Ichikawa, Takayuki; Kojima, Yoshitsugu

    A lithium silicon alloy was synthesized by mechanical alloying method. Hydrogen storage properties of this Li-Si-H system were studied. During hydrogenation of the lithium silicon alloy, lithium atom was extracted from the alloy and lithium hydride was generated. Equilibrium hydrogen pressures for desorption and absorption reactions were measured in a temperature range from 400 to 500 °C to investigate the thermodynamic characteristics of the system, which can reversibly store 5.4 mass% hydrogen with smaller reaction enthalpy than simple metal Li. Li absorbing alloys, which have been widely studied as a negative electrode material for Li ion rechargeable batteries, can be used as hydrogen storage materials with high hydrogen capacity.

  3. Exploring adsorption and desorption characteristics of molecular hydrogen on neutral and charged Mg nanoclusters: A first principles study

    NASA Astrophysics Data System (ADS)

    Banerjee, Paramita; Chandrakumar, K. R. S.; Das, G. P.

    2016-05-01

    To surmount the limitations of bulk MgH2 for the purpose of hydrogen storage, we report here, a detailed first principles density functional theory (DFT) based study on the structure and stability of neutral (Mgm) and positively charged (Mgm+) Mg nanoclusters of different sizes (m = 2, 4, 8 and 12) and their interaction with molecular hydrogen (H2). Our results demonstrate that H2 is weakly bound to the Mg nanoclusters through van der Waals interactions. Incorporation of Grimme's dispersion correction (D3) in the DFT based exchange-correlation functionals leads to improved accuracy of H2 interaction energy (IE) values that fall within an energy window (between physisorption and chemisorption) desirable for hydrogen storage. Energy decomposition analysis reveals the significance of polarization energy for these Mg-H2 binding. Ab-initio molecular dynamics simulation shows that complete dehydrogenation from these Mg nanoclusters occur at ∼100 °C which is a significant improvement over bulk MgH2 (∼300 °C).

  4. Partial hydrogenation induced interaction in a graphene-SiO2 interface: irreversible modulation of device characteristics.

    PubMed

    Iwasaki, Takuya; Muruganathan, Manoharan; Schmidt, Marek E; Mizuta, Hiroshi

    2017-01-26

    The transformation of systematic vacuum and hydrogen annealing effects in graphene devices on the SiO2 surface is reported based on experimental and van der Waals interaction corrected density functional theory (DFT) simulation results. Vacuum annealing removes p-type dopants and reduces charged impurity scattering in graphene. Moreover, it induces n-type doping into graphene, leading to the improvement of the electron mobility and conductivity in the electron transport regime, which are reversed by exposing to atmospheric environment. On the other hand, annealing in hydrogen/argon gas results in smaller n-type doping along with a decrease in the overall conductivity and carrier mobility. This degradation of the conductivity is irreversible even the graphene devices are exposed to ambience. This was clarified by DFT simulations: initially, silicon dangling bonds were partially terminated by hydrogen, subsequently, the remaining dangling bonds became active and the distance between the graphene and SiO2 surface decreased. Moreover, both annealing methods affect the graphene channel including the vicinity of the metal contacts, which plays an important role in asymmetric carrier transport.

  5. Dependences of Characteristics of Sensors Based on Tin Dioxide on the Hydrogen Concentration and Humidity of Gas Mixture

    NASA Astrophysics Data System (ADS)

    Gaman, V. I.; Almaev, A. V.

    2017-05-01

    An expression is obtained for the energy band bending eφsH on the surface of the SnO2 film in the clean air + hydrogen mixture. It is assumed that the value of eφsH depends not only on the surface charge density of adsorbed oxygen ions O¯, but also on the negative charged hydroxyl groups (OH¯). The results of the analysis of the dependences of eφsH on the hydrogen concentration {n}_{{H}_2} and the absolute humidity of the gas mixture obtained during the operation of the sensor in the thermo-cyclic mode are presented. A method for the determining {n}_{{H}_2} in the examined gas mixture is proposed. The method based on the dependence of eφsH on the hydrogen concentration established during the calibration of the sensor is proposed. The dependences of the energy band bending on the SnO2 surface at {n}_{{H}_2} = 0 and the conductivity of the sensor on its temperature during the heating period are discussed.

  6. Investigation of Hydrogen Adsorption on Single Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Nam, Sang-Hun; Jeong, Seong Hun; Lee, Soon-Bo; Boo, Jin-Hyo

    We have investigated adsorption and desorption condition of atomic hydrogen on single-walled nanotubes (SWCNTs) using ultraviolet photoelectron spectroscopy (UPS) and thermal desorption spectroscopy (TDS). The SWCNTs were made by the high pressure carbon monoxide (HiPCO) method. In our results, we observe from UPS data absorptive states reduce with increasing hydrogen doses and a new peak is developed near 8.6 eV and other points. But this peak is gradually diminished with pumping time. The TDS data show two characteristic peaks at 640 and 790K. By comparing with density functional calculations, we propose these peaks to be related to the presence of atomic hydrogen. Therefore, we can know that there are two adsorption sites on SWCNTs. Also we observed physisorption and chemisorption site by pumping time. We note that the UPS data are fully recoverable after hydrogen desorption at 1200K.

  7. Activated carbon catalyst for selective oxidation of hydrogen sulphide: on the influence of pore structure, surface characteristics, and catalytically-active nitrogen

    SciTech Connect

    Baskova, Svetlana; Baker, Frederick S; Wu, Xianxian; Armstrong, Timothy R.; Schwartz, Viviane

    2007-01-01

    The catalytic oxidation of hydrogen sulphide (H2S) on various activated carbon materials was studied. The effects of pore structure, surface characteristics, and nitrogen content on the activity and selectivity of the carbons towards oxidation of H2S were investigated. It was found that a high volume of both micropores and small mesopores, in combination with a relatively narrow pore size distribution, were crucial for the retention of sulphur dioxide (SO2), a by-product of H2S oxidation. For the retention of carbonyl sulphide (COS), another H2S oxidation by-product, high surface reactivity with a significant amount of basic groups were found to be important. The only carbon with all these characteristics, and consequently the carbon that was able to retain both H2S and COS for an extended period of time, was an experimental product, 'WSC'. This carbon was found to be superior to the other carbons studied, exhibiting high activity and selectivity for oxidation of H2S to sulphur. H2S breakthrough capacities and selectivity values of the carbons were found to be dependent on the nitrogen content of the carbons. In a hydrogen stream, carbons possessing the highest nitrogen contents exhibited the greatest H2S breakthrough capacities but, at the same time, the lowest selectivity with respect to sulphur formation. In reformate streams, the maximum breakthrough capacity and greatest selectivity were exhibited by carbons with a nitrogen content of about 1-1.5 wt%.

  8. Observation of proton-coupled electron transfer by transient absorption spectroscopy in a hydrogen-bonded, porphyrin donor-acceptor assembly.

    PubMed

    Damrauer, Niels H; Hodgkiss, Justin M; Rosenthal, Joel; Nocera, Daniel G

    2004-05-20

    Proton-coupled electron transfer (PCET) kinetics of a Zn(II) porphyrin donor noncovalently bound to a naphthalene-diimide acceptor through an amidinium-carboxylate interface have been investigated by time-resolved spectroscopy. The S1 singlet excited-state of a Zn(II) 2-amidinium-5,10,15,20-tetramesitylporphyrin chloride (ZnP-beta-AmH+) donor is sufficiently energetic (2.04 eV) to reduce a carboxylate-diimide acceptor (DeltaG degrees = -460 mV, THF). Static quenching of the porphyrin fluorescence is observed and time-resolved measurements reveal more than a 3-fold reduction in the S1 lifetime of the porphyrin upon amidinium-carboxylate formation (THF, 298 K). Picosecond transient absorption spectra of the free ZnP-beta-AmH+ in THF reveal the existence of an excited-state isosbestic point between the S1 and T1 states at lambdaprobe = 650 nm, providing an effective 'zero-kinetics' background on which to observe the formation of PCET photoproducts. Distinct rise and decay kinetics are attributed to the build-up and subsequent loss of intermediates resulting from a forward and reverse PCET reaction, respectively (kPCET(fwd) = 9 x 108 s-1 and kPCET(rev) = 14 x 108 s-1). The forward rate constant is nearly 2 orders of magnitude slower than that measured for covalently linked Zn(II) porphyrin-acceptor dyads of comparable driving force and D-A distance, establishing the importance of a proximal proton network in controlling charge transport.

  9. Characteristics of hydrogen storage by spillover on Pt-doped carbon and catalyst-bridged metal organic framework.

    PubMed

    Stuckert, Nicholas R; Wang, Lifeng; Yang, Ralph T

    2010-07-20

    Metal dispersion is a crucially important factor for hydrogen spillover storage on metal/carbon materials. For Pt on carbon (Pt/C), dispersion into nearly 2 nm clusters or nanoparticles is necessary to facilitate spillover. On an effective Pt/C spillover sorbent, temperature-programmed desorption (TPD) results reveal the highest hydrogen signal is from the high-energy Pt edges, steps or (110) surfaces, even though the (111) faces are more abundant. Previous theoretical studies showed the high-energy sites (including the 110 face) are by far the most preferred for effective splitting of hydrogen. These are in significantly smaller fractions for larger particles, and thus the larger particles are less efficient. In addition, the rate-limiting step for spillover on effective Pt/C is identified by the susceptibility to isotopic differences, first-order behavior and isolation from catalyzed H(2)/HD/D(2) equilibrium measurements; we conclude it is the spillover step or surface diffusion. We extended our analysis to a review of our previous work, spillover on metal organic frameworks (MOFs). This has been achieved by bridging a commercial H(2) dissociation catalyst (Pt/C) to MOFs, large enhancement factors (up to 8) were observed. Unlike Pt/C sorbents, sample-to-sample consistency in storage capacity on the bridged MOF samples is difficult to achieve. Inconsistency in the enhancements by spillover is shown; however, significant enhancement factors are still observed when samples are prepared and activated properly. Common pitfalls (and their consequences) in sample preparation for both Pt/C and bridged MOFs are discussed in detail.

  10. Microstructure and hydrogenation properties of a melt-spun non-stoichiometric Zr-based Laves phase alloy

    SciTech Connect

    Zhang, Tiebang Zhang, Yunlong; Li, Jinshan; Kou, Hongchao; Hu, Rui; Xue, Xiangyi

    2016-01-15

    Alloy with composition of Zr{sub 0.9}Ti{sub 0.1}V{sub 1.7} off normal stoichiometric proportion is selected to investigate the effect of defects introduced by non-stoichiometry on hydrogenation kinetics of Zr–Ti–V Laves phase alloys. Microstructure and phase constituent of melt-spun ribbons have been investigated in this work. The activation process, hydrogenation kinetics, thermodynamics characteristics and hydride phase constituent of as-cast alloy and melt-spun ribbons are also compared. Comparing with the as-cast alloy, the dominant Laves phase ZrV{sub 2} is preserved, V-BCC phase is reduced and α-Zr phase is replaced by a small amount of Zr{sub 3}V{sub 3}O phase in melt-spun ribbons. Melt-spun ribbons exhibit easy activation and fast initial hydrogen absorption on account of the increased specific surface area. However, the decrease in unit cell volume of the dominant phase leads to the decrease in hydrogen absorption capacity. Melt-spinning technique raises the equilibrium pressure and decreases the stability of hydride due to the decrease of unit cell volume and the elimination of α-Zr phase, respectively. Melt-spun ribbons with fine grains show improved hydrogen absorption kinetics comparing with that of the as-cast alloy. Meanwhile, the prevalent micro twins observed within melt-spun ribbons are believed to account for the improved hydrogen absorption kinetics. - Highlights: • Role of defects on hydrogenation kinetics of Zr-based alloys is proposed. • Microstructure and hydrogenation properties of as-cast/melt-spun alloy are compared. • Melt-spinning technique improves the hydrogenation kinetics of Zr{sub 0.9}Ti{sub 0.1}V{sub 1.7} alloy. • Refined grains and twin defects account for improved hydrogen absorption kinetics.

  11. Role of catalyst characteristics in electrocatalytic hydrogenation: Reduction of benzaldehyde and acetophenone on carbon felt/Pd electrodes

    SciTech Connect

    Polcaro, A.M.; Palmas, S.; Dernini, S. . Dipartimento di Ingegneria Chimica e Materiali)

    1993-07-01

    The hydrogenation of benzaldehyde and acetophenone was investigated at two carbon felt-supported Pd electrocatalysts, prepared by two different methods. The faradaic yield and the selectivity of the reaction were found to be greatly affected by the preparation conditions of the catalyst. A model, based on a reaction electrocatalytic mechanism, involving two parallel steps through which alcohol and hydrocarbon are generated from the reactant adsorbed on different active sites, was performed. The kinetics was described by means of the Langmuir-Hinshelwood rate equations, and the kinetic and equilibrium parameters were determined for both electrocatalysts.

  12. Absorption-Desorption Compressor for Spaceborne/Airborne Cryogenic Refrigerators.

    DTIC Science & Technology

    Refrigerant compressors, *Refrigeration systems), Spaceborne, Airborne, Cryogenics, Gases, Absorption, Desorption, Hydrogen, Hydrides, Lanthanum compounds, Nickel alloys, Joule Thomson effect , Heat transfer

  13. The influence of lipid characteristics on the formation, in vitro release, and in vivo absorption of protein-loaded SLN prepared by the double emulsion process.

    PubMed

    Yang, Rui; Gao, Renchao; Li, Fang; He, Haibing; Tang, Xing

    2011-02-01

    To study the influence of lipid characteristics on the formation, in vitro release, and in vivo absorption of solid lipid nanoparticles (SLN) prepared by the double emulsion method. Stearic acid (SA), octadecyl alcohol (OA), cetyl palmitate (CP), glyceryl monostearate (GM), glyceryl palmitostearate (GP), glyceryl tripalmitate (GT), and glyceryl behenate (GB) were selected as the representatives of different kinds of lipids, insulin and thymopentin (TP5) were selected as the model protein drugs. Before preparation, the contact angles between water and lipids were determined to investigate their hydrophobicity. The influence of lipid hydrophobicity or lipid solution viscosity on the preparation of primary emulsion, double emulsion, and SLN were studied by evaluating the particle size, state, and stability of the systems. CP-SLN, GT-SLN, and GP-SLN were selected to be loaded with insulin and TP5 for the in vitro release and in vivo absorption examination. After oral administration to diabetic rats, the pharmacological availability (PA) of insulin-CP-SLN, insulin-GP-SLN, and insulin-GT-SLN were determined. The hydrophobicity order of the lipids was GM

  14. Optical absorption measurements of hydrogen chloride at high temperature and high concentration in the presence of water using a tunable diode laser system for application in pyrohydrolysis non-ferrous industrial process control.

    PubMed

    Tzanetakis, Tommy; Susilo, Robin; Wang, Zhenyou; Padmanabhan, Arathi; Davis, Boyd R; Thomson, Murray J

    2015-06-01

    A tunable diode laser (TDL) was used to measure hydrogen chloride (HCl) spectra at 5747 cm(-1) (1.74 μm) and temperatures of 25-950 °C in a quartz cell. The purpose was to evaluate the capability of monitoring HCl concentration under pyrohydrolysis conditions using a near-infrared (NIR) laser. These conditions are characterized by 20-40% HCl, 2-40% H2O, and the presence of metal chloride vapors at temperatures of 600-1000 °C. Spectral peak area measurements of HCl-N2 mixtures at atmospheric pressure and a path length of 8.1 cm showed linear absorption behavior between concentrations of 5-95% and temperatures of 25-950 °C. Results from the addition of 2-40% water (H2O) indicate that the HCl peak area relationships are not affected for temperatures of 350-950 °C. Evaporating NiCl2 within the cell did not show spectral interference effects with HCl between 650 and 850 °C. The results from this work indicate that a near-infrared optical sensor is capable of measuring high HCl concentrations at high temperatures in the presence of high H2O content during pyrohydrolysis process conditions.

  15. Incomplete intestinal absorption of fructose.

    PubMed Central

    Kneepkens, C M; Vonk, R J; Fernandes, J

    1984-01-01

    Intestinal D-fructose absorption in 31 children was investigated using measurements of breath hydrogen. Twenty five children had no abdominal symptoms and six had functional bowel disorders. After ingestion of fructose (2 g/kg bodyweight), 22 children (71%) showed a breath hydrogen increase of more than 10 ppm over basal values, indicating incomplete absorption: the increase averaged 53 ppm, range 12 to 250 ppm. Four of these children experienced abdominal symptoms. Three of the six children with bowel disorders showed incomplete absorption. Seven children were tested again with an equal amount of glucose, and in three of them also of galactose, added to the fructose. The mean maximum breath hydrogen increases were 5 and 10 ppm, respectively, compared with 103 ppm after fructose alone. In one boy several tests were performed with various sugars; fructose was the only sugar incompletely absorbed, and the effect of glucose on fructose absorption was shown to be dependent on the amount added. It is concluded that children have a limited absorptive capacity for fructose. We speculate that the enhancing effect of glucose and galactose on fructose absorption may be due to activation of the fructose carrier. Apple juice in particular contains fructose in excess of glucose and could lead to abdominal symptoms in susceptible children. PMID:6476870

  16. Hydrogen production

    NASA Technical Reports Server (NTRS)

    England, C.; Chirivella, J. E.; Fujita, T.; Jeffe, R. E.; Lawson, D.; Manvi, R.

    1975-01-01

    The state of hydrogen production technology is evaluated. Specific areas discussed include: hydrogen production fossil fuels; coal gasification processes; electrolysis of water; thermochemical production of hydrogen; production of hydrogen by solar energy; and biological production of hydrogen. Supply options are considered along with costs of hydrogen production.

  17. Hydrogen production

    NASA Technical Reports Server (NTRS)

    England, C.; Chirivella, J. E.; Fujita, T.; Jeffe, R. E.; Lawson, D.; Manvi, R.

    1975-01-01

    The state of hydrogen production technology is evaluated. Specific areas discussed include: hydrogen production fossil fuels; coal gasification processes; electrolysis of water; thermochemical production of hydrogen; production of hydrogen by solar energy; and biological production of hydrogen. Supply options are considered along with costs of hydrogen production.

  18. Operating and environmental characteristics of Sigma Tau hydrogen masers used in the Very Long Baseline Array (VLBA)

    NASA Technical Reports Server (NTRS)

    Tucker, T. K.

    1989-01-01

    Presented here are the results obtained from performance evaluation of a pair of Sigma Tau Standards Corporation Model VLBA-112 active hydrogen maser frequency standards. These masers were manufactured for the National Radio Astronomy Observatory (NRAO) for use on the Very Long Baseline Array (VLBA) project and were furnished to the Jet Propulsion Laboratory (JPL) for the purpose of these tests. Tests on the two masers were performed in the JPL Frequency Standards Laboratory (FSL) and included the characterization of output frequency stability versus environmental factors such as temperature, humidity, magnetic field, and barometric pressure. The performance tests also included the determination of phase noise and Allan variance using both FSL and Sigma Tau masers as references. All tests were conducted under controlled laboratory conditions, with only the desired environmental and operational parameters varied to determine sensitivity to external environment.

  19. A randomized double-blind multi-center trial of hydrogen water for Parkinson's disease: protocol and baseline characteristics.

    PubMed

    Yoritaka, Asako; Abe, Takashi; Ohtsuka, Chigumi; Maeda, Tetsuya; Hirayama, Masaaki; Watanabe, Hirohisa; Saiki, Hidemoto; Oyama, Genko; Fukae, Jiro; Shimo, Yasushi; Hatano, Taku; Kawajiri, Sumihiro; Okuma, Yasuyuki; Machida, Yutaka; Miwa, Hideto; Suzuki, Chikako; Kazama, Asuka; Tomiyama, Masahiko; Kihara, Takeshi; Hirasawa, Motoyuki; Shimura, Hideki; Hattori, Nobutaka

    2016-05-12

    Our previous randomized double-blind study showed that drinking hydrogen (H2) water for 48 weeks significantly improved the total Unified Parkinson's Disease Rating Scale (UPDRS) score of Parkinson's disease (PD) patients treated with levodopa. We aim to confirm this result using a randomized double-blind placebo-controlled multi-center trial. Changes in the total UPDRS scores from baseline to the 8(th), 24(th), 48(th), and 72(nd) weeks, and after the 8(th) week, will be evaluated. The primary endpoint of the efficacy of this treatment in PD is the change in the total UPDRS score from baseline to the 72(nd) week. The changes in UPDRS part II, UPDRS part III, each UPDRS score, PD Questionnaire-39 (PDQ-39), and the modified Hoehn and Yahr stage at these same time-points, as well as the duration until the protocol is finished because additional levodopa is required or until the disease progresses, will also be analyzed. Adverse events and screening laboratory studies will also be examined. Participants in the hydrogen water group will drink 1000 mL/day of H2 water, and those in the placebo water group will drink normal water. One-hundred-and-seventy-eight participants with PD (89 women, 89 men; mean age: 64.2 [SD 9.2] years, total UPDRS: 23.7 [11.8], with levodopa medication: 154 participants, without levodopa medication: 24 participants; daily levodopa dose: 344.1 [202.8] mg, total levodopa equivalent dose: 592.0 [317.6] mg) were enrolled in 14 hospitals and were randomized. This study will confirm whether H2 water can improve PD symptoms. UMIN000010014 (February, 13, 2013).

  20. Physicochemical characteristics and gastrointestinal absorption behaviors of S-propargyl-cysteine, a potential new drug candidate for cardiovascular protection and antitumor treatment.

    PubMed

    Ma, Guo; Zhang, Lin; Zhang, Peng; Bao, Xingfei; Zhou, Ning; Shi, Qingling; Zheng, Yuanting; Liu, Hongrui; Bu, Fengjiao; Zhang, Ying; Huang, Wenjie; Wang, Fen; Zhu, Yizhun; Cai, Weimin

    2015-04-01

    1. As a potential new drug candidate for cardiovascular protection and antitumor treatment, the physicochemical properties, gastrointestinal (GI) absorption behaviors and mechanisms of S-propargyl-cysteine (SPRC) were investigated in this study. 2. SPRC exhibited favorable solubility in aqueous media. The log P and log D values were low (≤1.93 ± 0.08). The pKa in the acidic and basic regions was 2.08 ± 0.02 and 8.72 ± 0.03, respectively. The isoelectric point was 5.40 ± 0.02. SPRC was stable in the rat GI fluids, and showed no obvious adsorption and metabolism in the rat GI tract. 3. SPRC displayed poor gastric absorption and favorable intestinal absorption in the rat in situ GI perfusion model. Absorption rate constants (ka), hourly absorption percentage (P) and apparent permeability coefficient (Papp) of SPRC in the small intestine were ≥0.77 ± 0.06 h(-1), 59.25 ± 4.02% and (7.99 ± 0.88) × 10(-5 )cm/s, respectively. Absorption of SPRC exhibited a certain dependence on physiological pH and absorption region. Absorption of SPRC was not inhibited by l-methionine and 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid. 4. SPRC showed favorable oral absorption. It can be categorized as a BCS class I drug. The membrane pore transport appeared to be one of the predominant absorption modes for SPRC.

  1. Spin Changing Collisions of Hydrogen

    NASA Technical Reports Server (NTRS)

    Zygelman, Bernard

    2006-01-01

    We discuss spin changing collisions of hydrogen atoms. Employing a fully quantal theory we calculate and present new collision data. We discuss the respective roles of spin exchange and long range magnetic interactions in collisonal redistribution of sub-level populations. The calculated atomic data is needed for accurate modeling of 21 cm line emission/absorption by primordial hydrogen in the early universe.

  2. Effects of hydrogen on metals

    NASA Technical Reports Server (NTRS)

    Cataldo, C. E.

    1969-01-01

    Several rules to guide choice of materials, and methods of welding, electroplating, and heat treatment will provide a method for minimizing failures in storage tanks and related hardware. Failures are caused by high-pressure hydrogen effects, the formation of hydrides in titanium, and hydrogen absorption through various metals processing techniques.

  3. Absorption and distribution characteristics of 5-fluorouracil (5-FU) after an application to the liver surface in rats in order to reduce systemic side effects.

    PubMed

    Kodama, Yukinobu; Fumoto, Shintaro; Nishi, Junya; Nakashima, Mikiro; Sasaki, Hitoshi; Nakamura, Junzo; Nishida, Koyo

    2008-05-01

    The present study was undertaken to elucidate the absorption and distribution characteristics of 5-fluorouracil (5-FU) after its application to the liver surface in rats to examine the possibility of reducing the systemic side effects of this agent. 5-FU was applied to the surface of the liver by employing a cylindrical diffusion cell. Approximately 69% of the dose was absorbed in 360 min. The time course of the change in the amount of 5-FU remaining in the diffusion cell obeyed first-order kinetics. Also, a linear relationship was observed between the apparent permeability coefficient, P app, and the reciprocal of the square root of the molecular weight of several compounds including 5-FU. The estimated P app value of 5-FU was in good agreement with the experimental value. The plasma concentration of 5-FU was low (<1.2 microg/ml) until 360 min after the application. Following i.v. administration, 5-FU was rapidly eliminated from the plasma and could not be detected at 120 min. In the analysis of tissue distribution, the liver was divided into three sites; the region under the diffusion cell attachment site (site 1), the treated lobe excluding site 1 (site 2), and untreated lobes (site 3). After being administered i.v., 5-FU mainly distributed in the kidney, and the concentration in the liver was significantly lower than that in kidney, spleen, or heart. After its application to the liver surface, however, 5-FU preferentially distributed at site 1, and was not detected at the other sites or in other tissues. Thus, these results suggested the possibility of a reduction in the systemic side effect of 5-FU on its application to the liver surface.

  4. Variations in the structure and electrochemical characteristics of membrane electrode assemblies during the endurance testing of hydrogen-air fuel cells

    NASA Astrophysics Data System (ADS)

    Avakov, V. B.; Aliev, A. D.; Bogdanovskaya, V. A.; Ivanitskii, B. A.; Kazanskii, L. P.; Kapustin, A. V.; Korchagin, O. V.; Landgraf, I. K.; Tarasevich, M. P.; Chalykh, A. E.

    2015-05-01

    Variations in the characteristics of a membrane-electrode assembly (MEA) are studied during the endurance testing of a hydrogen-air fuel cell (FC) based on a Nafion 212 proton conducting membrane and platinum catalysts. It is shown that the voltage drop observed during MEA testing was mainly due to physicochemical transformations of the cathode catalyst, i.e., the oxidation of platinum and its subsequent recrystallization with nanoparticle coarsening. It is established that the rate of degradation increases along with temperature and loading, and with periodic FC depressurization. It is concluded that the enhancing effects of additional factors of degradation, e.g., platinum ion transport to the proton-conducting membrane and corrosion of the carbon carrier, were responsible for these processes.

  5. Absorption characteristic of paeoniflorin-6'-O-benzene sulfonate (CP-25) in in situ single-pass intestinal perfusion in rats.

    PubMed

    Yang, Xiao-Dan; Wang, Chun; Zhou, Peng; Yu, Jun; Asenso, James; Ma, Yong; Wei, Wei

    2016-09-01

    1. Paeoniflorin-6'-O-benzene sulfonate (CP-25) was synthesized to improve the poor oral absorption of paeoniflorin (Pae). 2. This study was performed to investigate the absorptive behavior and mechanism of CP-25 in in situ single-pass intestinal perfusion in rats, using Pae as a control. 3. The results showed that intestinal absorption of CP-25 was neither segmental nor sex dependent. However, the main segment of intestine that absorbed Pae was the duodenum. Furthermore, passive transport was confirmed to be the main absorption pattern of CP-25. More importantly, the absorption of CP-25 was much higher than Pae in the small intestine. 4. Among the ABC transporter inhibitors, the absorption rate of Pae increased in the presence of P-gp inhibitors verapamil and GF120918, which indicated that Pae was a substrate of P-glycoprotein (P-gp), however, such was not observed in the presence of breast cancer resistance protein and multidrug resistance-associated protein 2. Finally, the ABC transporter inhibitors did not have any significant impact on CP-25 as demonstrated in the parallel studies. 5. CP-25 could improve the poor absorption of Pae, which may be attributed to both the lipid solubility enhancement and its resistance to P-gp-mediated efflux.

  6. The effects of calcium hydroxide on hydrogen chloride emission characteristics during a simulated densified refuse-derived fuel combustion process.

    PubMed

    Chiang, Kung-Yuh; Jih, Jer-Chyuan; Lin, Kae-Long

    2008-08-30

    This study investigated the effects of different calcium hydroxide (Ca(OH)(2)) addition methods on the potential for hydrogen chloride (HCl) formation in a simulated densified refuse-derived fuel (RDF-5) with single metal combustion system. These experiments were conducted at 850 degrees C with the Ca(OH)(2) spiked in the RDF-5 production or injection in the flue gas treatment system. The results indicated that the potential for HCl formation was decreased significantly by Ca(OH)(2) spiked in the RDF-5 production or injection in the flue gas treatment system. However, the Ca(OH)(2) injection method in the flue gas for HCl emission reduction was better than other method. According to the relationship between the HCl emission and amount of Ca(OH)(2) injected or spiked, it is interesting to find that when the Ca(OH)(2) injected or spiked ranged from 0% to 5%, the potential for HCl formation in the single metal combustion system decreases significantly with increasing Ca(OH)(2) injected or spiked ratio. A corresponding increase in the amount of CaCl(2) partitioned to the fly ash was observed. However, with the ratio of Ca(OH)(2) higher than 5%, the amount of HCl formation showed that no further significant variation occurred with increasing Ca(OH)(2) spiked ratio.

  7. Stability of Hydrated Methylamine: Structural Characteristics and H2N···H–O Hydrogen Bonds

    SciTech Connect

    Lv, Sha-Sha; Liu, Yi-Rong; Huang, Teng; Feng, Ya-Juan; Jiang, Shuai; Huang, Wei

    2015-04-23

    Methylamine is the simplest aliphatic amine found in human urine, blood, and tissues. It is thought to play a significant part in central nervous system disturbances observed during renal and hepatic disease. In this work we have investigated the methylamine hydration clusters using a basin hopping (BH) algorithm with the density functional theory (DFT). The results presented herein yield a detailed understanding of the structure and stability for a system consisting of one methylamine molecule and up to seven waters: the most stable geometries arise from a fusion of tetramer or pentamer rings; by the geometrical parameters and topological parameters analysis, the strengths of the H2N···H–O hydrogen bonds of the global minima increase as the sizes of clusters increase, except for n = 5 where there is a slight fluctuation. This work may shed light on the form mechanism of methylamine existing in organisms and the hydration structures of larger molecules containing amino functional groups and their interaction with the water molecules nearby.

  8. Analytical Investigation of the Effect of Turbopump Design on Gross-Weight Characteristics of a Hydrogen-Propelled Nuclear Rocket

    NASA Technical Reports Server (NTRS)

    Rohlik, Harold E.; Crouse, James E.

    1959-01-01

    The effect of turbopump design on rocket gross weight was investigated for a high-pressure bleed-type hydrogen-reactor long-range rocket with a fixed mission. Axial-flow, mixed-flow, and centrifugal pumps driven by single and twin turbines were considered. With an efficiency of 0.7 assumed for all pumps, the lowest rocket gross weights were obtained with an axial-flow or a mixed-flow pump driven by a single turbine of at least eight stages. All turbopump combinations could be used, however, with gross weight varying less than 8 percent for a given payload. Turbopump efficiencies have a significant effect on the ratio of gross weight to payload with the magnitude of the effect determined by the ratio of rocket structural weight to total propellant weight. One point in pump efficiency is worth 0.2 percent in gross weight for a given payload with a structural weight parameter of 0.1 and 0.6 percent with a structural weight parameter of 0.2. Turbine and pump weights are much less significant in terms of gross-to-pay weight ratio than the efficiencies of these components. One point in pump efficiency is equivalent to approximately 13 percent in pump weight, while 1 point in turbine efficiency is equivalent to about 7 percent in turbine weight.

  9. Effect of technique parameters on characteristics of hydrogen-free DLC films deposited by surface wave-sustained plasma

    NASA Astrophysics Data System (ADS)

    Xu, Junqi; Kousaka, Hiroyuki; Umehara, Noritsugu; Diao, Dongfeng

    2006-01-01

    Hydrogen-free diamond-like carbon (DLC) films were deposited by a new-type surface wave-sustained plasma physical vapor deposition (SWP-PVD) system under various technique conditions. Electron density was measured by a Langmuir probe, while the film thickness and hardness were characterized using a surface profilometer and a nanoindenter, respectively. Surface morphology was investigated by an atomic force microscope (AFM). It was found that the electron density and deposition rate increased following the increase in microwave power, target voltage, or gas pressure. The typical electron density and deposition rate were about 1.87-2.04×10 11 cm -3 and 1.61-14.32 nm/min respectively. AFM images indicated that the grains of films changes as the technique parameters vary. The optical constants, refractive index n and extinction coefficient k, were obtained using an optical ellipsometry. With the increase in microwave power from 150 to 270 W, the extinction coefficient of DLC films increased from 0.05 to 0.27 while the refractive index decreased from 2.31 to 2.18.

  10. Studies on the Structural Transformation of Pt Clusters with Adsorbed Hydrogen on α-Al2O3(0001) Using Multiple Scattering Approach to Pt L3-edge Polarized X-Ray Absorption Near Edge Structure Spectra for the Pt Cluster

    NASA Astrophysics Data System (ADS)

    Ohtani, Kunihiro

    1998-03-01

    The X-ray absorption near edge structure (XANES) or the Extended X-ray absorption fine structure (EXAFS) study with polarization dependence is useful for determining the structures of the metal clusters. We have calculated Pt L3-edge XANES spectra for various structures of Pt clusters with adsorbed hydrogen, such as the one-layer-thick raft, and the hemispherical and spherical structures on α-Al2O3(0001), using the full multiple scattering approach. Comparison of the calculated results with the experimental results have yielded important information. With an increase in the spherically symmetric character of Pt clusters, the influence of Pt-support interaction on the XANES spectra decreases, that is, the hydrogen-Pt interaction plays a dominant role in such cases. We expect that Pt clusters with the one-layer-thick raft, or hemispherical structures are on the top site of surface oxygen atoms.

  11. Hydrogen Generation Via Sodium Borohydride

    NASA Astrophysics Data System (ADS)

    Mohring, Richard M.; Wu, Ying

    2003-07-01

    Along with the technological challenges associated with developing fuel cells and hydrogen burning engines, a major issue that must be addressed to ensure the ultimate success of a hydrogen economy is the ability to store and transport hydrogen effectively. Millennium Cell has developed and patented a proprietary system for storing and generating hydrogen gas called Hydrogen on Demand™. The system releases the hydrogen stored in fuel solutions of sodium borohydride as needed through an easily controllable catalytic process. The fuel itself is water-based, rich in hydrogen content, and non-flammable. It can be stored in plastic containers under no pressure. After the hydrogen from the fuel is consumed, the remaining product, sodium metaborate (chemically similar to borax), can be recycled back into fresh fuel. In this paper, an overview of the Hydrogen on Demand™ technology is presented along with data showing the performance characteristics of practical hydrogen generation systems. A brief discussion of sodium borohydride regeneration chemistry is also provided.

  12. Bile salts and calcium absorption

    PubMed Central

    Webling, D. D'A.; Holdsworth, E. S.

    1966-01-01

    1. The study of the effect of bile salts on enhancing calcium absorption in the rachitic chick has been extended to bile salts not present in chick bile, e.g. glycine conjugates and bile alcohol sulphates. 2. Bile and bile salts cause an increase in calcium absorption from sparingly soluble calcium hydrogen phosphate when compared with a suspension of calcium hydrogen phosphate in saline. 3. If the bile ducts of normal rats are tied the absorption of calcium from calcium hydrogen phosphate decreases but can be restored by giving bile salts with the calcium salt. 4. Bile salts increase solubility in water of the sparingly soluble calcium salts, phytate and phosphate at pH values between 6 and 8. 5. Bile salts increase the solubility in lipid solvents of calcium in approximately the same proportion as they increase the absorption of calcium from the gut. 6. The physiological role of bile in calcium absorption and its mode of action are discussed. PMID:4291037

  13. The nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their amorphous thin films

    NASA Astrophysics Data System (ADS)

    Karatay, Ahmet; Aksoy, Çagla; Gul Yaglioglu, H.; Elmali, Ayhan; Kürüm, Ulaş; Ateş, Aytunç; Gasanly, Nizami

    2011-07-01

    We investigated the nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their very thin amorphous films by open aperture (OA) Z-scan and pump-probe techniques. The linear absorption spectra indicated a blue shift in energy with increasing film thickness. This can be attributed to the quantum confinement effect. For both 4 ns and 65 ps pulse durations the two photon absorption coefficients of Ga0.90In0.10Se and Ga0.85In0.15Se crystals increased with increasing input intensities. The life time of the localized defect states was measured as 3 ns for both Ga0.90In0.10Se and Ga0.85In0.15Se films while it was around 10 ns for GaSe and InSe films. Open aperture Z-scan experiments with a 4 ns pulse duration did not exhibit any saturable absorption behavior for thin films since the life time of localized defect states was not long enough to saturate these films. Thinner films exhibited saturable absorption and thicker films exhibited nonlinear absorption for a 65 ps pulse duration. This behavior was attributed to increasing localized defect states with increasing film thickness. The experimental curves were fitted to the theory of the open aperture Gaussian-beam Z-scan based on the Adomian decomposition method incorporating one photon, two photon, and free carrier absorptions and their saturations. The lowest saturation intensity threshold for the Ga0.90In0.10Se film was found to be 1.38 × 102 MW cm - 2 for 43 nm film thickness.

  14. Vaporization reduction characteristics of aqueous ammonia solutions by the addition of ethylene glycol, glycerol and glycine to the CO2 absorption process.

    PubMed

    Seo, Jong-Beom; Jeon, Soo-Bin; Kim, Je-Young; Lee, Gang-Woo; Jung, Jong-Hyeon; Oh, Kwang-Joong

    2012-01-01

    Aqueous ammonia (NH3) solution can be used as an alternative absorption for the control of CO2 emitted from flue gases due to its high absorption capacity, fast absorption rate and low corrosion problem. The emission of CO2 from iron and steel plants requires much attention, as they are higher than those emitted from power plants at a single point source. In the present work, low concentration ammonia liquor, 9 wt.%, was used with various additives to obtain the kinetic properties using the blast furnace gas model. Although a solution with a high ammonia concentration enables high CO2 absorption efficiency, ammonium ions are lost as ammonia vapor, resulting in reduced CO2 absorption due to the lower concentration of the ammonia absorbent. To decrease the vaporization of ammonia, ethylene glycol, glycerol and glycine, which contain more than one hydroxyl radical, were chosen. The experiments were conducted at 313 K similar to the CO2 absorption conditions for the blast furnace gas model.

  15. Current density-voltage and admittance characteristics of hydrogenated nanocrystalline cubic SiC/crystalline Si heterojunction diodes prepared with varying H2 gas flow rates

    NASA Astrophysics Data System (ADS)

    Tabata, Akimori; Imori, Yoshikazu

    2015-02-01

    N-doped hydrogenated nanocrystalline cubic SiC (nc-3C-SiC:H) thin films were deposited on p-type crystalline Si (c-Si) substrates by hot-wire chemical vapor deposition from a SiH4/CH4/H2/N2 gas mixture. The current density-voltage and the admittance characteristics of the nc-3C-SiC:H/c-Si heterojunction diodes were investigated. As the H2 gas flow rate (F(H2)) increased from 25 to 100 sccm, the ideality factor and saturation current density deceased from 1.87 to 1.47 and 1.6 × 10-7 to 9.9 × 10-9 A/cm2, respectively. However, they increased to 1.82 and 3.0 × 10-7 A/cm2, respectively, when F(H2) was further increased to 1000 sccm. The relaxation time, evaluated from the admittance characteristics, decreased from 2.9 × 10-5 to 2.4 × 10-6 s with an increase in F(H2). The apparent built-in voltage, evaluated from the capacitance-voltage characteristics, decreased from 1.05 to 0.60 eV. These findings were mainly caused by interfacial defects, generated by a high density of H radicals during the nc-3C-SiC:H deposition process. The interfacial defect density increased with an increase in F(H2), resulting in deterioration of the diode characteristics.

  16. X-ray Absorption Spectroscopy and Density Functional Theory Studies of [(H3buea)FeIII-X]n1 (X= S2-, O2-,OH-): Comparison of Bonding and Hydrogen Bonding in Oxo and Sulfido Complexes

    SciTech Connect

    Dey, Abhishek; Hocking, Rosalie K.; Larsen, Peter; Borovik, Andrew S.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC, SSRL

    2006-09-27

    Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

  17. Measurements of the volt-ampere characteristics and the breakdown voltages of direct-current helium and hydrogen discharges in microgaps

    SciTech Connect

    Klas, M.; Matejčik, Š.; Radjenović, B.; Radmilović-Radjenović, M.

    2014-10-15

    The discharge phenomena for micro meter gap sizes include many interesting problems from engineering and physical perspectives. In this paper, the authors deal with the experimental and theoretical results of the breakdown voltage and current-voltage characteristics of the direct-current helium and hydrogen discharges. The measurements were performed at a constant pressure of around one atmosphere, while varying the gap size between two parallel plane tungsten electrodes between 1 μm and 100 μm. From the measured breakdown voltage curves, the effective yields and the ionization coefficients were derived for both gases. Present data for the ionization coefficients correlate with the data obtained for the breakdown voltage curves measured for fixed 100 μm interelectrode separation. The current-voltage characteristics were plotted for the various gap sizes illustrating the role of the field emission effects in the microgaps. Based on the Fowler-Nordheim theory, the enhancement factors were determined. The gap spacing dependence of the field emission current can be explained by the introduction of two ideas, the first being a space charge effect by emitted electrons, and the second a change in the breakdown mechanism. Experimental results, presented here, demonstrate that Townsend phenomenology breaks down when field emission becomes the key mechanism affecting the breakdown and deforming the left hand side of the breakdown voltage curves.

  18. Modeling hydrogen-cyanide absorption in fires

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.; Islas, A.

    1981-01-01

    A mathematical model is developed for predicting blood concentrations of cyanide as functions of exposure time to constant levels of cyanide in the atmosphere. A toxic gas (which may form as a result of decomposition of combustion materials used in transportation vehicles) is breathed into the alveolar space and transferred from the alveolar space to the blood by a first-order process, dependent on the concentration of the toxicant in the alveolar space. The model predicts that blood cyanide levels are more sensitive to the breathing cycle than to blood circulation. A model estimate of the relative effects of CO and HCN atmospheres, generated in an experimental chamber with an epoxy polymer, shows that toxic effects of cyanide occur long before those of carbon monoxide.

  19. Influence of hydrogen-bonding configurations on the physical properties of hydrogenated amorphous silicon

    NASA Astrophysics Data System (ADS)

    Manfredotti, C.; Fizzotti, F.; Boero, M.; Pastorino, P.; Polesello, P.; Vittone, E.

    1994-12-01

    We analyzed the physical properties of hydrogenated amorphous silicon (a-Si:H) samples grown by plasma-enhanced chemical vapor deposition, by means of infrared spectroscopy, mass-density, and optical measurements. We applied the usual infrared spectroscopic techniques to evaluate the amount of incorporated hydrogen and to investigate the influence of the Si-H bonding configurations on the optical and electronic properties of a-Si:H obtained by this widely used deposition process, and with parameters so chosen as to obtain films having state of the art characteristics. We carried out an exhaustive study of the different infrared absorption peaks, generally ascribed to different bonding configurations of H in Si, with a view to distinguishing the different contributions of SiH, SiH2 (SiH2)n to the spectral response of the material and to relating them to deposition temperature. The correlation of this infrared spectral analysis with mass-density measurements has evidenced that, for hydrogen content below 10 at. %, isolated SiH and SiH2 bonds occur, whereas, with higher hydrogen concentrations, the formation of (SiH2)n chains gives rise to empty cavities where hydrogen is preferentially incorporated. In addition, optical measurements show that samples deposited at temperatures below 170 °C exhibit energy gaps and defect densities, which are quite different to those expected if only the effects of SiH groups are considered.

  20. The influence of alkalinity of portland cement on the absorption characteristics of superabsorbent polymers (SAP) for use in internally cured concrete

    NASA Astrophysics Data System (ADS)

    Tabares Tamayo, Juan D.

    The concrete industry increasingly emphasizes advances in novel materials that promote construction of more resilient infrastructure. Due to its potential to improve concrete durability, internal curing (IC) of concrete by means of superabsorbent polymers (SAP) has been identified as one of the most promising technologies of the 21st century. The addition of superabsorbent polymers into a cementitious system promotes further hydration of cement by providing internal moisture during the hardening and strength development periods, and thus limits self-desiccation, shrinkage, and cracking. This thesis presents the work performed on the series of cement pastes with varying alkalinity of their pore solutions to provide a better understanding of: (1) the influence of the chemistry of the pore solution (i.e. its level of alkalinity and the type of ionic species present) on the absorption capacity of SAP, and (2) the effectiveness of SAP with different absorption capacities as an internal curing agent. This research work was divided into three stages: (a) materials characterization, (b) measurement of absorption capacity of SAP in synthetic pore solutions, and (c) evaluation of the internal curing effectiveness of SAP. During the first stage (Materials Characterization), pore solutions were extracted from the fresh (5 minutes old) cement pastes prepared using cements with three different levels of alkalinity. The pH values of the extracted solutions were determined (using the pH meter) and their chemical analysis was performed by means of titration (concentration of hydroxyl), ion chromatography (sulfates and chlorides), atomic absorption (AA) and inductively coupled plasma optical emission spectrometry (ICP) (sodium, potassium and calcium). The commercial SAP adopted for this study was used with "as-supplied" gradation and with the finer gradation obtained by grinding the original polymer in the 6850 Cryomilling Freezer/Mill. The physical properties of these SAP's, such