The study of hydrogen electrosorption in layered nickel foam/palladium/carbon nanofibers composite electrodes

International Nuclear Information System (INIS)

Skowronski, J.M.; Czerwinski, A.; Rozmanowski, T.; Rogulski, Z.; Krawczyk, P.

2007-01-01

In the present work, the process of hydrogen electrosorption occurring in alkaline KOH solution on the nickel foam/palladium/carbon nanofibers (Ni/Pd/CNF) composite electrodes is examined. The layered Ni/Pd/CNF electrodes were prepared by a two-step method consisting of chemical deposition of a thin layer of palladium on the nickel foam support to form Ni/Pd electrode followed by coating the palladium layer with carbon nanofibers layer by means of the CVD method. The scanning electron microscope was used for studying the morphology of both the palladium and carbon layer. The process of hydrogen sorption/desorption into/from Ni/Pd as well as Ni/Pd/CNF electrode was examined using the cyclic voltammetry method. The amount of hydrogen stored in both types of composite electrodes was shown to increase on lowering the potential of hydrogen sorption. The mechanism of the anodic desorption of hydrogen changes depending on whether or not CNF layer is present on the Pd surface. The anodic peak corresponding to the removal of hydrogen from palladium is lower for Ni/Pd/CNF electrode as compared to that measured for Ni/Pd one due to a partial screening of the Pd surface area by CNF layer. The important feature of Ni/Pd/CNF electrode is anodic peak appearing on voltammetric curves at potential ca. 0.4 V more positive than the peak corresponding to hydrogen desorption from palladium. The obtained results showed that upon storing the hydrogen saturated Ni/Pd/CNF electrode at open circuit potential, diffusion of hydrogen from carbon to palladium phase occurs due to interaction between carbon fibers and Pd sites on the nickel foam support

Thermophysical Properties of Matter - the TPRC Data Series. Volume 12. Thermal Expansion Metallic Elements and Alloys

Science.gov (United States)

1975-01-01

the thermal expansion of metallic elements, alloys, and intermetallic compounds. We believe there is also much food for reflection by the specialist...24 39 Plutonium Pu ........ ............... 260 40’ t Polonium Po ..... ............... 270 41* Potassium K ..... ............... 271 42...923 209 NIckel-Palladium NI-Pd..................926 210 * Nickel-Pitaum Ni-Pt.................90 211 Nickel-Silicon NI-SI.................932 212

New developments in the analysis and measurement of thicknesses by {beta}-particle excitation of X fluorescent rays; Nouveaux developpements de l'analyse et de la mesure des epaisseurs par excitation des raies de fluorescence X au moyen de particules {beta}; Novye usovershenstvovaniya analiza i izmereniya plotnosti putem vozbuzhdeniya fluorestsiruyushchikh spektrov rentgenovskogo lucha beta-chastitsami; Nuevos adelantos en el analisis y la medicion de espesores mediante la excitacion de rayos X por particulas beta

Energy Technology Data Exchange (ETDEWEB)

Martinelli, P [Commissariat a l' Energie Atomique, Saclay (France); Seibel, G [Institut de Recherches de la Siderurgie, St-Germain-en-Laye (France)

1962-01-15

The method of analysing and measuring the thickness of deposits by {beta}-X fluorescence which we previously described has been further developed. Using Pm{sup 147} and Kr{sup 85} sources, it is possible to reduce the background observed with Sr{sup 90}. We quote the results obtained for various thickness measurements of metal deposits, an analysis of the solutions, and the continuous measurement of calcium and iron in core samples. We describe experiments made for analysis of the X-radiation by crystal. (author) [French] Le procede d'analyse et de mesure des epaisseurs de depots par fluorescence {beta}-X que nous avons precedemment decrit a fait l'objet de nouveaux developpements. L'emploi de sources de {sup 147}Pm et de {sup 85}Kr permet de reduire le bruit de fond que l'on observe avec le {sup 90}Sr. Nous donnons les resultats obtenus pour diverses mesures d'epaisseurs de depots metalliques, l'analyse des solutions et la mesure en continu du calcium et du fer dans les carottes de minerais. Nous decrivons les essais effectues en vue d'analyser le rayonnement X au moyen d'un cristal. (author) [Spanish] Los autores han introducido nuevos perfeccionamientos en su procedimiento de analisis y de medicion de espesores de depositos por fluorescencia de rayos X excitada por particulas beta. La utilizacion de fuentes de {sup 147}Pm y de {sup 85}Kr permite reducir la actividad de fondo que se observa empleando {sup 90}Sr. Los autores exponen los resultados obtenidos en materia de mediciones de espesores de depositos metalicos, analisis de soluciones y medicion continua del calcio y del hierro en muestras de minerales extraidas por sondeo. Tambien describen los ensayos realizados con miras a analizar los rayos X por medio de un cristal. (author) [Russian] Protsess analiza i izmereniya plotnosti sloev putem fluorestsiruyushchikh beta- i rentgenovskikh luchej, kotoryj opisyvalsya nami ran'she, byl predmetom novykh usovershenstvovanij. Ispol'zovanie istochnikov prometeya-147 i

Non-invasive prenatal diagnosis using cell-free fetal DNA technology: applications and implications.

Science.gov (United States)

Hall, Alison; Bostanci, A; Wright, C F

2010-01-01

Cell-free fetal DNA and RNA circulating in maternal blood can be used for the early non-invasive prenatal diagnosis (NIPD) of an increasing number of genetic conditions, both for pregnancy management and to aid reproductive decision-making. Here we present a brief review of the scientific and clinical status of the technology, and an overview of key ethical, legal and social issues raised by the analysis of cell-free fetal DNA for NIPD. We suggest that the less invasive nature of the technology brings some distinctive issues into focus, such as the possibility of broader uptake of prenatal diagnosis and access to the technology directly by the consumer via the internet, which have not been emphasised in previous work in this area. We also revisit significant issues that are familiar from previous debates about prenatal testing. Since the technology seems to transect existing distinctions between screening and diagnostic tests, there are important implications for the form and process involved in obtaining informed consent or choice. This analysis forms part of the work undertaken by a multidisciplinary group of experts which made recommendations about the implementation of this technology within the UK National Health Service. Copyright 2010 S. Karger AG, Basel.

Deuterium absorption in Mg{sub 70}Al{sub 30} thin films with bilayer catalysts: A comparative neutron reflectometry study

Energy Technology Data Exchange (ETDEWEB)

Poirier, Eric [National Research Council Canada/Canadian Neutron Beam Centre, Bldg. 459, Chalk River Laboratories, Chalk River, ON, K0J 1J0 (Canada); Harrower, Chris T.; Kalisvaart, Peter [Chemical and Materials Engineering, University of Alberta and National Research Council Canada/National Institute for Nanotechnology, Edmonton, AB, T6G 2M9 (Canada); Bird, Adam [National Research Council Canada/Canadian Neutron Beam Centre, Bldg. 459, Chalk River Laboratories, Chalk River, ON, K0J 1J0 (Canada); Teichert, Anke [Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Instituut voor Kern-en Stralingsfysica and INPAC, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Laboratorium voor Vaste-Stoffysica en Magnetisme and INPAC, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Wallacher, Dirk; Grimm, Nico; Steitz, Roland [Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Mitlin, David [Chemical and Materials Engineering, University of Alberta and National Research Council Canada/National Institute for Nanotechnology, Edmonton, AB, T6G 2M9 (Canada); Fritzsche, Helmut, E-mail: Helmut.Fritzsche@nrc-cnrc.gc.ca [National Research Council Canada/Canadian Neutron Beam Centre, Bldg. 459, Chalk River Laboratories, Chalk River, ON, K0J 1J0 (Canada)

2011-05-05

Highlights: > Mg{sub 70}Al{sub 30} thin films studied for hydrogen absorption using in situ neutron reflectometry. > Films with Ta/Pd, Ti/Pd and Ni/Pd bilayer catalysts systematically compared. > Measurements reveals deuterium spillover from the catalysts to the MgAl phase. > The use of Ti-Pd bilayer offers best results in terms of amount absorbed and kinetics. > Key results cross-checked with X-ray reflectometry. - Abstract: We present a neutron reflectometry study of deuterium absorption in thin films of Al-containing Mg alloys capped with a Ta/Pd, Ni/Pd and Ti/Pd-catalyst bilayer. The measurements were performed at room temperature over the 0-1 bar pressure range under quasi-equilibrium conditions. The modeling of the measurements provided a nanoscale representation of the deuterium profile in the layers at different stages of the absorption process. The absorption mechanism observed was found to involve spillover of atomic deuterium from the catalyst layer to the Mg alloy phase, followed by the deuteration of the Mg alloy. Complete deuteration of the Mg alloy occurs in a pressure range between 100 and 500 mbar, dependent on the type of bilayer catalyst. The use of a Ti/Pd bilayer catalyst yielded the best results in terms of both storage density and kinetic properties.

Deuterium absorption in Mg70Al30 thin films with bilayer catalysts: A comparative neutron reflectometry study

International Nuclear Information System (INIS)

Poirier, Eric; Harrower, Chris T.; Kalisvaart, Peter; Bird, Adam; Teichert, Anke; Wallacher, Dirk; Grimm, Nico; Steitz, Roland; Mitlin, David; Fritzsche, Helmut

2011-01-01

Highlights: → Mg 70 Al 30 thin films studied for hydrogen absorption using in situ neutron reflectometry. → Films with Ta/Pd, Ti/Pd and Ni/Pd bilayer catalysts systematically compared. → Measurements reveals deuterium spillover from the catalysts to the MgAl phase. → The use of Ti-Pd bilayer offers best results in terms of amount absorbed and kinetics. → Key results cross-checked with X-ray reflectometry. - Abstract: We present a neutron reflectometry study of deuterium absorption in thin films of Al-containing Mg alloys capped with a Ta/Pd, Ni/Pd and Ti/Pd-catalyst bilayer. The measurements were performed at room temperature over the 0-1 bar pressure range under quasi-equilibrium conditions. The modeling of the measurements provided a nanoscale representation of the deuterium profile in the layers at different stages of the absorption process. The absorption mechanism observed was found to involve spillover of atomic deuterium from the catalyst layer to the Mg alloy phase, followed by the deuteration of the Mg alloy. Complete deuteration of the Mg alloy occurs in a pressure range between 100 and 500 mbar, dependent on the type of bilayer catalyst. The use of a Ti/Pd bilayer catalyst yielded the best results in terms of both storage density and kinetic properties.

Imprinted NanoVelcro Microchips for Isolation and Characterization of Circulating Fetal Trophoblasts: Toward Noninvasive Prenatal Diagnostics

OpenAIRE

Hou, Shuang; Chen, Jie-Fu; Song, Min; Zhu, Yazhen; Jan, Yu Jen; Chen, Szu Hao; Weng, Tzu-Hua; Ling, Dean-An; Chen, Shang-Fu; Ro, Tracy; Liang, An-Jou; Lee, Tom; Jin, Helen; Li, Man; Liu, Lian

2017-01-01

Circulating fetal nucleated cells (CFNCs) in maternal blood offer an ideal source of fetal genomic DNA for noninvasive prenatal diagnostics (NIPD). We developed a class of nanoVelcro microchips to effectively enrich a subcategory of CFNCs, i.e., circulating trophoblasts (cTBs) from maternal blood, which can then be isolated with single-cell resolution by a laser capture microdissection (LCM) technique for downstream genetic testing. We first established a nanoimprinting fabrication process to...

Time-Dependent Density Functional Theory Analysis of Triphenylamine-Functionalized Graphene Doped with Transition Metals for Photocatalytic Hydrogen Production.

Science.gov (United States)

Mota, Elder A V; Neto, Abel F G; Marques, Francisco C; Mota, Gunar V S; Martins, Marcelo G; Costa, Fabio L P; Borges, Rosivaldo S; Neto, Antonio M J C

2018-07-01

The electronic structures and optical properties of triphenylamine-functionalized graphene (G-TPA) doped with transition metals, using water as a solvent, were theoretically investigated to verify the efficiency of photocatalytic hydrogen production with the use of transition metals. This study was performed by Density Functional Theory and Time-dependent Density Functional Theory through Gaussian 09W software, adopting the B3LYP functional for all structures. The 6-31g(d) basis set was used for H, C and N atoms, and the LANL2DZ basis set for transition metals using the Effective Core Potentials method. Two approaches were adopted: (1) using single metallic dopants (Ni, Pd, Fe, Os and Pt) and (2) using combinations of Ni with the other dopants (NiPd, NiPt, NiFe and NiOs). The DOS spectra reveal an increase of accessible states in the valence shell, in addition to a gap decrease for all dopants. This doping also increases the absorption in the visible region of solar radiation where sunlight is most intense (400 nm to 700 nm), with additional absorption peaks. The results lead us to propose the G-TPA structures doped with Ni, Pd, Pt, NiPt or NiPd to be novel catalysts for the conversion of solar energy for photocatalytic hydrogen production, since they improve the absorption of solar energy in the range of interest for solar radiation; and act as reaction centers, reducing the required overpotential for hydrogen production from water.

[Analysis on Research Projects Supported by the National Natural Science Foundation of China at the National Institute of Parasitic Diseases during 2003-2013].

Science.gov (United States)

Zhou, Xiao-jun; Zheng, Bin; Yi, Feng-yun; Xiong, Yan-hong; Zhang, Min-qi

2015-04-01

The data of the National Natural Science Foundation (NSFC) projests obtained by the National Institute of Parasitic Diseases (NIPD), Chinese Center for Disease Control and Prevention (China CDC) during 2003-2013 were collected from internet-based science information system of NSFC, and NSFC search tool of Dingxiang Garden (http://nsfc.biomart.cn/). The number of funded projects, their subject classification and approved amount were analyzed, and compared with the other institutes of China CDC. Furthermore, the rationalization proposals were given in order to enhance the level of foundation management in the future.

Noninvasive Digital Detection of Fetal DNA in Plasma of 4-Week-Pregnant Women following In Vitro Fertilization and Embryo Transfer.

Directory of Open Access Journals (Sweden)

Bedri Karakas

Full Text Available The discovery of cell-free fetal DNA (cfDNA circulating in the maternal blood has provided new opportunities for noninvasive prenatal diagnosis (NIPD. However, the extremely low levels of cfDNA within a high background of the maternal DNA in maternal circulation necessitate highly sensitive molecular techniques for its reliable use in NIPD. In this proof of principle study, we evaluated the earliest possible detection of cfDNA in the maternal plasma by a bead-based emulsion PCR technology known as BEAMing (beads, emulsion, amplification, magnetics. Blood samples were collected from in vitro fertilization (IVF patients at 2 to 6 weeks following embryo transfer (i.e., 4 to 8 week pregnancies and plasma DNA was extracted. The genomic regions of both X and Y chromosome-specific sequences (AMELX and AMELY were concurrently amplified in two sequential PCRs; first by conventional PCR then by BEAMing. The positive beads either for AMELX or AMELY gene sequences were counted by a flow cytometer. Our results showed that the pregnancies yielding boys had significantly higher plasma AMELY gene fractions (0.512 ± 0.221 than the ones yielding girls (0.028 ± 0.003 or non-pregnant women (0.020 ± 0.005, P= 0.0059. Here, we clearly demonstrated that the BEAMing technique is capable of reliably detecting cfDNA in the blood circulation of 4-week-pregnant women, which is only two weeks after the embryo transfer. BEAMing technique can also be used to early detect fetal DNA alterations in other pregnancy-associated disorders.

Radiation-induced segregation in model alloys

Science.gov (United States)

Ezawa, T.; Wakai, E.; Oshima, R.

2000-12-01

The dependence of the size factor of solutes on radiation-induced segregation (RIS) was studied. Ni-Si, Ni-Co, Ni-Cu, Ni-Mn, Ni-Pd, and Ni-Nb binary solid solution alloys were irradiated with electrons in a high voltage electron microscope at the same irradiation conditions. A focused beam and a grain boundary were utilized to generate a flow of point defects to cause RIS. From the concentration profile obtained by an energy dispersive X-ray analysis, the amount of RIS was calculated. The amount of RIS decreased as the size of the solute increased up to about 10%. However, as the size increased further, the amount of RIS increased. This result shows that RIS is not simply determined by the size effect rule.

Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

Science.gov (United States)

Yeh, Chia-Hsien; Hung, Chia-Wei; Wu, Chun-Han; Lin, Yu-Cheng

2014-09-01

This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood.

Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

International Nuclear Information System (INIS)

Yeh, Chia-Hsien; Hung, Chia-Wei; Lin, Yu-Cheng; Wu, Chun-Han

2014-01-01

This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood. (paper)

Microstructure and transformation behaviour of Ni75−XTiXPd25 high temperature shape memory alloys

International Nuclear Information System (INIS)

Ramaiah, K.V.; Saikrishna, C.N.; Gouthama; Bhaumik, S.K.

2013-01-01

Highlights: ► Partitioning of elements during solidification of cast NiTiPd results in cored microstructure. ► Homogenized alloys consists of NiTiPd matrix with Ti2(Ni,Pd) precipitates. ► Transformation temperatures of NiTiPd alloy is strongly dependent on Ti content. ► Transformation hysteresis was found to be relatively low, in the range 7–12 °C. ► Lower fraction of second phases and twinless/small twin ratio martensite led to low hysteresis. -- Abstract: The effect of composition on microstructure, transformation behaviour and thermal stability of cast and homogenized Ni 75−X Ti X Pd 25 alloys (X = 49.7, 50.0 and 50.3 at.%) were studied. Results showed significant partitioning of the alloying elements during solidification, resulting in cored microstructure in the cast alloys. The interdendritic regions were depleted in Pd and richer in Ni compared to dendritic regions. The interdendritic regions also showed presence of a thread-like Ti-rich second phase. The microstructure of the homogenized alloys consisted of NiTiPd matrix phase interspersed with Ti 2 (Ni,Pd) second phase precipitates. The precipitate phase was found to be rich in Ni and depleted in Pd. EPMA analysis showed that significant redistribution of Ni concentration in the matrix and the precipitate phase takes place during homogenization. X-ray diffraction study confirmed the matrix phase at room temperature to be of orthorhombic B19 structure. Study showed that the transformation temperatures of the alloys were strongly dependent on Ti content. The martensite finish temperature (M f ) of 157 °C for stoichiometric-Ti alloy increased to 179 °C and decreased to 105 °C for Ti-rich and Ti-lean alloys, respectively. Also, the alloys showed relatively low transformation hysteresis in the range 7–12 °C. TEM micrographs showed the presence of twinless/small twin ratio martensite which minimizes the interfacial energy and hence lower hysteresis. The transformation stability upon stress

Improved ethanol electrooxidation performance by shortening Pd-Ni active site distance in Pd-Ni-P nanocatalysts

Science.gov (United States)

Chen, Lin; Lu, Lilin; Zhu, Hengli; Chen, Yueguang; Huang, Yu; Li, Yadong; Wang, Leyu

2017-01-01

Incorporating oxophilic metals into noble metal-based catalysts represents an emerging strategy to improve the catalytic performance of electrocatalysts in fuel cells. However, effects of the distance between the noble metal and oxophilic metal active sites on the catalytic performance have rarely been investigated. Herein, we report on ultrasmall (~5 nm) Pd-Ni-P ternary nanoparticles for ethanol electrooxidation. The activity is improved up to 4.95 A per mgPd, which is 6.88 times higher than commercial Pd/C (0.72 A per mgPd), by shortening the distance between Pd and Ni active sites, achieved through shape transformation from Pd/Ni-P heterodimers into Pd-Ni-P nanoparticles and tuning the Ni/Pd atomic ratio to 1:1. Density functional theory calculations reveal that the improved activity and stability stems from the promoted production of free OH radicals (on Ni active sites) which facilitate the oxidative removal of carbonaceous poison and combination with CH3CO radicals on adjacent Pd active sites.

An Overview of Surface Finishes and Their Role in Printed Circuit Board Solderability and Solder Joint Performance

Energy Technology Data Exchange (ETDEWEB)

Vianco, P.T.

1998-10-15

A overview has been presented on the topic of alternative surface finishes for package I/Os and circuit board features. Aspects of processability and solder joint reliability were described for the following coatings: baseline hot-dipped, plated, and plated-and-fused 100Sn and Sn-Pb coatings; Ni/Au; Pd, Ni/Pd, and Ni/Pd/Au finishes; and the recently marketed immersion Ag coatings. The Ni/Au coatings appear to provide the all-around best option in terms of solderability protection and wire bondability. Nickel/Pal ftishes offer a slightly reduced level of performance in these areas that is most likely due to variable Pd surface conditions. It is necessmy to minimize dissolved Au or Pd contents in the solder material to prevent solder joint embrittlement. Ancillary aspects that included thickness measurement techniques; the importance of finish compatibility with conformal coatings and conductive adhesives; and the need for alternative finishes for the processing of non-Pb bearing solders were discussed.

Electrical and photoelectric properties of PbGa{sub 2}Se{sub 4} single crystals; Ehlektricheskie i fotoehlektricheskie svojstva monokristalla PbGa{sub 2}Se{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Tagiev, B G; Tagiev, O B; Dzhabbarov, R B; Musaeva, N N [AN Azerbajdzhana, Inst. Fiziki, Baku (Azerbaijan)

1999-01-01

Thermal dependence of dark current spectral distribution of photocurrent and temperature quenching of photocurrent of PbGa{sub 2}Se{sub 4} single crystals are investigated. Concentrations and mobilities of free charge carriers, concentrations and activation energies of gaps, values of Fermi level and forbidden zone width are calculated.

Improved ethanol electrooxidation performance by shortening Pd–Ni active site distance in Pd–Ni–P nanocatalysts

Science.gov (United States)

Chen, Lin; Lu, Lilin; Zhu, Hengli; Chen, Yueguang; Huang, Yu; Li, Yadong; Wang, Leyu

2017-01-01

Incorporating oxophilic metals into noble metal-based catalysts represents an emerging strategy to improve the catalytic performance of electrocatalysts in fuel cells. However, effects of the distance between the noble metal and oxophilic metal active sites on the catalytic performance have rarely been investigated. Herein, we report on ultrasmall (∼5 nm) Pd–Ni–P ternary nanoparticles for ethanol electrooxidation. The activity is improved up to 4.95 A per mgPd, which is 6.88 times higher than commercial Pd/C (0.72 A per mgPd), by shortening the distance between Pd and Ni active sites, achieved through shape transformation from Pd/Ni–P heterodimers into Pd–Ni–P nanoparticles and tuning the Ni/Pd atomic ratio to 1:1. Density functional theory calculations reveal that the improved activity and stability stems from the promoted production of free OH radicals (on Ni active sites) which facilitate the oxidative removal of carbonaceous poison and combination with CH3CO radicals on adjacent Pd active sites. PMID:28071650

Effect of solute atoms on swelling in Ni alloys and pure Ni under He + ion irradiation

Science.gov (United States)

Wakai, E.; Ezawa, T.; Imamura, J.; Takenaka, T.; Tanabe, T.; Oshima, R.

2002-12-01

The effects of solute atoms on microstructural evolutions have been investigated using Ni alloys under 25 keV He + irradiation at 500 °C. The specimens used were pure Ni, Ni-Si, Ni-Co, Ni-Cu, Ni-Mn and Ni-Pd alloys with different volume size factors. The high number densities of dislocation loops about 1.5×10 22 m -3 were formed in the specimens irradiated to 1×10 19 ions/m 2, and they were approximately equivalent, except for Ni-Si. The mean size of loops tended to increase with the volume size factor of solute atoms. In a dose of 4×10 20 ions/m 2, the swelling was changed from 0.2% to 4.5%, depending on the volume size factors. The number densities of bubbles tended to increase with the absolute values of the volume size factor, and the swelling increased with the volume size factors. This suggests that the mobility of helium and vacancy atoms may be influenced by the interaction of solute atoms with them.

Effect of solute elements in Ni alloys on blistering under He + and D + ion irradiation

Science.gov (United States)

Wakai, E.; Ezawa, T.; Takenaka, T.; Imamura, J.; Tanabe, T.; Oshima, R.

2007-08-01

Effects of solute atoms on microstructural evolution and blister formation have been investigated using Ni alloys under 25 keV He + and 20 keV D + irradiation at 500 °C to a dose of about 4 × 10 21 ions/m 2. The specimens used were pure Ni, Ni-Si, Ni-Co, Ni-Cu, Ni-Mn and Ni-Pd alloys. The volume size factors of solute elements for the Ni alloys range from -5.8% to +63.6%. The formations of blisters were observed in the helium-irradiated specimens, but not in the deuteron-irradiated specimens. The areal number densities of blisters increased with volume size difference of solute atoms. The dependence of volume size on the areal number densities of blisters was very similar to that of the number densities of bubbles on solute atoms. The size of the blisters inversely decreased with increasing size of solute atoms. The formation of blisters was intimately related to the bubble growth, and the gas pressure model for the formation of blisters was supported by this study.

Characterization of Ternary NiTiPd High-Temperature Shape-Memory Alloys under Load-Biased Thermal Cycling

Science.gov (United States)

Bigelow, Glen S.; Padula, Santo A.; Noebe, Ronald D.; Garg, Anita; Gaydosh, Darrell

2010-01-01

While NiTiPd alloys have been extensively studied for proposed use in high-temperature shape-memory applications, little is known about the shape-memory response of these materials under stress. Consequently, the isobaric thermal cyclic responses of five (Ni,Pd)49.5Ti50.5 alloys with constant stoichiometry and Pd contents ranging from 15 to 46 at. pct were investigated. From these tests, transformation temperatures, transformation strain (which is proportional to work output), and unrecovered strain per cycle (a measure of dimensional instability) were determined as a function of stress for each alloy. It was found that increasing the Pd content over this range resulted in a linear increase in transformation temperature, as expected. At a given stress level, work output decreased while the amount of unrecovered strain produced during each load-biased thermal cycle increased with increasing Pd content, during the initial thermal cycles. However, continued thermal cycling at constant stress resulted in a saturation of the work output and nearly eliminated further unrecovered strain under certain conditions, resulting in stable behavior amenable to many actuator applications.

Application of microscopy technology in thermo-catalytic methane decomposition to hydrogen

Energy Technology Data Exchange (ETDEWEB)

Mei, Irene Lock Sow, E-mail: irene.sowmei@gmail.com; Lock, S. S. M., E-mail: serenelock168@gmail.com; Abdullah, Bawadi, E-mail: bawadi-abdullah@petronas.com.my [Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Sri Iskandar, 31750, Perak (Malaysia)

2015-07-22

Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production because it produces pure hydrogen without any CO{sub x} emissions. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both specific activity and operational lifetime have been developed. In this work, bimetallic Ni-Pd on gamma alumina support have been developed for methane cracking process by using co-precipitation and incipient wetness impregnation method. The calcined catalysts were characterized to determine their morphologies and physico-chemical properties by using Brunauer-Emmett-Teller method, Field Emission Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy and Thermogravimetric Analysis. The results suggested that that the catalyst which is prepared by the co-precipitation method exhibits homogeneous morphology, higher surface area, have uniform nickel and palladium dispersion and higher thermal stability as compared to the catalyst which is prepared by wet impregnation method. This characteristics are significant to avoid deactivation of the catalysts due to sintering and carbon deposition during methane cracking process.

Highly sensitive glucose sensor based on monodisperse palladium nickel/activated carbon nanocomposites.

Science.gov (United States)

Koskun, Yağmur; Şavk, Aysun; Şen, Betül; Şen, Fatih

2018-06-20

Glucose enzyme biosensors have been used for a variety of applications such as medical diagnosis, bioprocess engineering, beverage industry and environmental scanning etc. and there is still a growing interest in glucose sensors. For this purpose, addressed herein, as a novel glucose sensor, highly sensitive activated carbon (AC) decorated monodisperse nickel and palladium alloy nanocomposites modified glassy carbon electrode (Ni-Pd@AC/GCE NCs) have been synthesized by in-situ reduction technique. Raman Spectroscopy (RS), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA) were used for the characterization of the prepared non-enzymatic glucose sensor. The characteristic sensor properties of the Ni-Pd@AC/GCE electrode were compared with Ni-Pd NCs/GCE, Ni@AC/GCE and Pd@AC/GCE and the results demonstrate that the AC is very effective in the enhancement of the electrocatalytic properties of sensor. In addition, the Ni-Pd@AC/GCE nanocomposites showed a very low detection limit of 0.014 μM, a wide linear range of 0.01 mM-1 mM and a very high sensitivity of 90 mA mM -1  cm -2 . Furthermore, the recommended sensor offer the various advantageous such as facile preparation, fast response time, high selectivity and sensitivity. Lastly, monodisperse Ni-Pd@AC/GCE was utilized to detect glucose in real sample species. Copyright © 2018 Elsevier B.V. All rights reserved.

First steps of ion beam mixing: study by X-ray reflectometry and neutron diffraction

International Nuclear Information System (INIS)

Le Boite, M.G.

1987-12-01

There are several processes involved in ion beam mixing: ballistic processes, chemical driving forces and radiation enhanced diffusion. Experiments usually performed on bilayers irradiated with heavy elements and characterized by Rutherford backscattering (R.B.S.), have shown that the measured mixing rate is always higher than the calculated one, taking into account ballistic effects only. Besides classical R.B.S. experiments on NiAu and NiPt bilayers irradiated with Xe, we have used another technique of characterization: X-ray reflectometry and neutron diffraction, performed on multilayers irradiated with He. The systems are NiAu, NiPt, NiPd and NiAg, which behave similarly from the ballistic point of view, but have very different heats of mixing. In these experiments, the range of deposited energy density is very low, in contrast to heavy ions irradiation: this has allowed us to reach very low diffusion coefficient, never observed before. The dependence of the diffusion coefficient on the heat of mixing is in agreement with the one theoretically calculated. For the NiAg system, which has a positive heat of mixing, the measured diffusion coefficient is smaller than the ballistic one: a decrease of the ballistic mixing rate is seen for the first time. In this work, we have shown the interest of the reflectometry techniques (X-ray and neutrons); we have used a simple model to analyze the ion beam mixing, when elementary processes are involved

Effects of the imposed pressure differential conditions on duoplasmatron performance

International Nuclear Information System (INIS)

Oztarhan, A.

1988-01-01

The duoplasmatron plasma source (D.P.T.) was modified to allow access to the arc discharge (to measure the discharge properties) and to vary independently the pressures in different volumes of the arc with the aim of seeing if this freedom would help in optimising the output. The duoplasmatron plasma source was operated under normal running condition (N.R.C.), positive imposed pressure differential condition (P.I.P.D.C.) and negative imposed pressure differential condition (N.I.P.D.C.) and the corresponding properties of the plasma output were measured. Running the duoplasmatron under P.I.P.D. condition did not seem to improve the output as compared to that under N.R.C. However, running the duoplasmatron under N.I.P.D. condition seemed to be advantageous as the output increased by about 30%. It was observed that the back pressure was critical in maintaining the arc and the gap pressure could be lowered much below the normal minimum (while the arc was on) if back pressure was kept above a critical value. The results showed that the effects of varying the dimensions of the intermediate electrode nozzle on the output could be understood in terms of the effect of changes in these dimensions on the relative pressures. An empirical expression for the effect of the pressure ratio was developed from the observations and compared with the experimental results. The reasons for various results can be related to the plasma emission mechanism. (author). 8 refs, 6 figs, 1 tab

A novel non-invasive detection method for the FGFR3 gene mutation in maternal plasma for a fetal achondroplasia diagnosis based on signal amplification by hemin-MOFs/PtNPs.

Science.gov (United States)

Chen, Jun; Yu, Chao; Zhao, Yilin; Niu, Yazhen; Zhang, Lei; Yu, Yujie; Wu, Jing; He, Junlin

2017-05-15

The small amount of cell-free fetal DNA (cffDNA) can be a useful biomarker for early non-invasive prenatal diagnosis (NIPD) of achondroplasia. In this study, a novel non-invasive electrochemical DNA sensor for ultrasensitive detecting FGFR3 mutation gene, a pathogenic gene of achondroplasia, based on biocatalytic signal materials and the biotin-streptavidin system are presented. Notably encapsulation of hemin in metal-organic frameworks-based materials (hemin-MOFs) and platinum nanoparticles (PtNPs) were used to prepare hemin-MOFs/PtNPs composites via a one-beaker-one-step reduction. We utilized hemin-MOFs/PtNPs for signal amplification because the promising hemin-MOFs/PtNPs nanomaterial has remarkable ability of catalyze H 2 O 2 as well as excellent conductivity. To further amplify the electrochemical signal, reduced graphene oxide-tetraethylene pentamine (rGO-TEPA), gold nanoparticles and streptavidin were selected for modification of the electrode to enhance the conductivity and immobilize more biotin-modified capture probe (Bio-CP) through the high specificity and superior affinity between streptavidin and biotin. The electrochemical signal was primarily derived from the synergistic catalysis of H 2 O 2 by hemin and PtNPs and recorded by Chronoamperometry. Under the optimal conditions, this newly designed biosensor exhibited sensitive detection of FGFR3 from 0.1fM to 1nM with a low detection limit of 0.033fM (S/N=3). We proposed that this ultrasensitive biosensor is useful for the early non-invasive prenatal diagnosis of achondroplasia. Copyright © 2016 Elsevier B.V. All rights reserved.

Improvement of energy conversion efficiency and power generation in direct borohydride-hydrogen peroxide fuel cell: The effect of Ni-M core-shell nanoparticles (M = Pt, Pd, Ru)/Multiwalled Carbon Nanotubes on the cell performance

Science.gov (United States)

Hosseini, M. G.; Mahmoodi, R.

2017-12-01

In this study, core@shell nanoparticles with Ni as a core material and Pt, Pd and Ru as shell materials are synthesized on multiwalled carbon nanotube (MWCNT) as catalyst support using the sequence reduction method. The influence of Ni@Pt, Ni@Pd and Ni@Ru core@shell nanoparticles on MWCNT toward borohydride oxidation in alkaline solution is investigated by various three-electrode electrochemical techniques. Also, the impact of these anodic electrocatalysts on the performance of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) is evaluated. The structural and morphological properties of electrocatalysts are studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The results of three electrode investigations show that Ni@Pd/MWCNT has excellent catalytic activity since borohydride oxidation current density on Ni@Pd/MWCNT (34773.27 A g-1) is 1.37 and 9.19 times higher than those of Ni@Pt/MWCNT (25347.27 A g-1) and Ni@Ru/MWCNT (3782.83 A g-1), respectively. Also, the energy conversion efficiency and power density of DBHPFC with Ni@Pd/MWCNT (246.82 mW cm-2) increase to 34.27% and 51.53% respect to Ni@Pt/MWCNT (162.24 mW cm-2) and Ni@Ru/MWCNT (119.62 mW cm-2), respectively. This study reveals that Ni@Pd/MWCNT has highest activity toward borohydride oxidation and stability in fuel cell.

Effect of Pd Surface Roughness on the Bonding Process and High Temperature Reliability of Au Ball Bonds

Science.gov (United States)

Huang, Y.; Kim, H. J.; McCracken, M.; Viswanathan, G.; Pon, F.; Mayer, M.; Zhou, Y. N.

2011-06-01

A 0.3- μm-thick electrolytic Pd layer was plated on 1 μm of electroless Ni on 1 mm-thick polished and roughened Cu substrates with roughness values ( R a) of 0.08 μm and 0.5 μm, respectively. The rough substrates were produced with sand-blasting. Au wire bonding on the Ni/Pd surface was optimized, and the electrical reliability was investigated under a high temperature storage test (HTST) during 800 h at 250°C by measuring the ball bond contact resistance, R c. The average value of R c of optimized ball bonds on the rough substrate was 1.96 mΩ which was about 40.0% higher than that on the smooth substrate. The initial bondability increased for the rougher surface, so that only half of the original ultrasonic level was required, but the reliability was not affected by surface roughness. For both substrate types, HTST caused bond healing, reducing the average R c by about 21% and 27%, respectively. Au diffusion into the Pd layer was observed in scanning transmission electron microscopy/ energy dispersive spectroscopy (STEM-EDS) line-scan analysis after HTST. It is considered that diffusion of Au or interdiffusion between Au and Pd can provide chemically strong bonding during HTST. This is supported by the R c decrease measured as the aging time increased. Cu migration was indicated in the STEM-EDS analysis, but its effect on reliability can be ignored. Au and Pd tend to form a complete solid solution at the interface and can provide reliable interconnection for high temperature (250°C) applications.

Study of neutron-proton pairing in N=Z unstable nuclei through transfer reactions

International Nuclear Information System (INIS)

Le Crom, B.

2016-01-01

A nucleus is described as a set of independent neutrons and protons linked by a mean-field potential. However, in order to have a better description one needs to take into account some residual interactions such as pairing. Neutron-neutron and proton-proton pairings are well-studied but neutron-proton pairing is not well-known. np pairing can be isovector pairing such as nn and pp pairing or isoscalar which is yet unknown. Over-binding of N=Z nuclei could be a manifestation of np pairing. We have studied np pairing through transfer reactions. In this case, the cross-section of np pair transfer is expected to be enhanced in the presence of important np pairing. np pairing is expected to be important in N=Z nuclei with high J orbitals. Since the development of radioactive beam facilities, such beams are only available. The experiment was performed at GANIL with an efficient set-up so as to detect products from the (p, 3 He) transfer reaction. This reaction is affected by isovector and isoscalar np pairing. We used 56 Ni and 52 Fe beams so as to see the effect of the occupancy of 0f 7/2 shell on the np pairing. First, we analysed the data from the 56 Ni(p,d) 55 Ni reaction and we compared the results with the literature to validate analysis procedure. After analysing data from the 56 Ni(p, 3 He) 54 Co reaction and extracting the population of the various states of 54 Co, we obtained information about the relative intensity between isoscalar and isovector np pairing in 56 Ni showing the predominance of isovector np pairing in this nucleus. Moreover, in the framework of developing a new charged particle detector, research on the discrimination of light nuclei using pulse shape analysis was performed and is also presented. (author)

PREPARATION, CHARACTERIZATIONS AND MODIFICATION OF Ni-Pd/NATURAL ZEOLITE CATALYSTS

Directory of Open Access Journals (Sweden)

Wega Trisunaryanti

2010-06-01

Full Text Available Preparation, and modification of Ni-Pd/natural zeolite as well as their characterizations had been carried out. The aim of this research for the fututure is to prepare the best characters catalyst for the conversion of waste plastics fraction to gasoline fraction (C5-C12 hydrocarbons. The preparation of catalysts was performed by reacting a natural zeolite with the precursor of Ni(NO32. 9H2O and PdCl2 in an ammonia solution (25%. The modifications were performed by varying the rasio of Ni/Pd loaded to the zeolite, whereas the Pd was previously loaded and total metal content was 1 wt.% based on the zeolite. The characterization of catalysts included determination of acidity gravimetrically by adsorption of ammonia or pyridine vapour  base method, metal content by Atomic Adsorption Spectrophotometer (AAS and X-ray Fluoresence (XRF and crystallinity by X-ray Diffraction (XRD. The treatment of catalysts using Etilene Diamine Tetra Acetic acid  (EDTA was performed to study the metal distribution on the outer or inner surface of the zeolite. The characterization results showed that the loading of metals to the zeolite increased its acidity and decreased its spesific surface area, however, did not defect its crystallnity.  The metals loaded on the zeolite were distributed inside the pore and at outer surface of the zeolite. For all catalyst samples, the acidities determined using ammonia were higher than those of pyridine, and the acidities determined before the EDTA treatment was lower than those after the treatment.  Metal contents of the zeolite before the EDTA treatment were higher than those after the treatment. The EDTA treatment enhanced the crystallinity of the sampel. The relationship between the metal rasio towards the acidity of the catalyst samples were in variation. Catalyst samples produced in this research have good characters, thus promisingly can be used for conversion process of waste plastics to gasoline fraction.    Keywords

Nickel foam/polyaniline-based carbon/palladium composite electrodes for hydrogen storage

International Nuclear Information System (INIS)

Skowronski, Jan M.; Urbaniak, Jan

2008-01-01

The sandwich-like nickel/palladium/carbon electrodes exhibiting ability to absorb hydrogen in alkaline solution are presented. Electrodes were prepared by successive deposition of palladium and polyaniline layers on nickel foam substrate followed by heat treatment to give Ni/Pd/C electrode. It was shown that thermal conversion of polymer into carbon layer and subsequent thermal activation of carbon component bring about the modification of the mechanism of reversible hydrogen sorption. It was proven that carbon layer, interacting with Pd catalyst, plays a considerable role in the process of hydrogen storage. In the other series of experiments, Pd particles were dispersed electrochemically on carbon coating leading to Ni/C/Pd system. The adding of the next carbon layer resulted in Ni/C/Pd/C electrodes. Electrochemical properties of the electrodes depend on both the sequence of Pd and C layers and the preparation/activation of carbon coating. Electrochemical behavior of sandwich-like electrodes in the reaction of hydrogen sorption/desorption was characterized in 6 M KOH using the cyclic voltammetry method and the results obtained were compared to those for Ni/Pd electrode. The anodic desorption of hydrogen from electrodes free and containing carbon layer was considered after the potentiodynamic as well as potentiostatic sorption of hydrogen. The influence of the sorption potential and the time of rest of electrodes at a cut-off circuit on the kinetics of hydrogen recovery were examined. The results obtained for Ni/Pd/C electrodes indicate that the displacement of hydrogen between C and Pd phase takes place during the rest at a cut-off circuit. Electrodes containing carbon layer require longer time for hydrogen electrosorption. On the other hand, the presence of carbon layer in electrodes is advantageous because a considerable longer retention of hydrogen is possible, as compared to Pd/Ni electrode. Hydrogen stored in sandwich-like electrodes can instantly be

Self-regulated magnetic fluid hyperthermia: A potential cancer therapy

Science.gov (United States)

Bagaria, Hitesh Ghanshyam

An emerging cancer therapy, self-regulated magnetic fluid hyperthermia (MFH), is the motivation for this work. In this therapy, cancer is annihilated by heating the tumor to desired therapeutic temperatures (˜45°C) by using magnetic nanoparticles of controlled Curie temperatures (Tc). This work was aimed at preparing and characterizing FePt, NiPd and NiPt nanoparticles for self-regulated MFH because their Tc could be tuned by changing their composition. Based on the excellent colloidal stability, size tunability and toxicity considerations, FePt was an obvious choice for self-regulated MFH. The 3.2 nm Fe61Pt39 particles displayed a Tc of 151°C, which is well below the Tc of bulk Fe61Pt39 (˜327°C). To reach the desired Tc of 45°C the composition of iron needs to be increased. However, a major obstacle was the formation of iron oxide shells with increase in iron composition of the particles. A recent finding that the composition of individual FePt particles deviated significantly from the average value encouraged us to study the mechanism of formation of FePt particles. Our analysis showed that early in the reaction the particles were Pt-rich and as the reaction proceeded the Fe content increased. It was found that the wide distribution in the composition of individual particles started early in the synthesis, suggesting that the compositional variability may be attributed to the Pt nuclei. The synthesized FePt particles are unsuitable for biological applications because of their hydrophobic surface. Hence, their surface was modified by ligand exchange with mercapto alkanoic acids. After ligand exchange, stable FePt dispersions could be formed in alkaline water. The study revealed that both the carboxylate and thiol groups were required to form stable FePt dispersions. In addition, 15 nm gold particles were successfully conjugated to genetically modified adenoviruses that selectively bind to cancer tumors. We also modeled the thermal transport in tissues during

Infectious Diseases of Poverty, the first five years.

Science.gov (United States)

Wang, Wei; Chen, Jin; Sheng, Hui-Feng; Wang, Na-Na; Yang, Pin; Zhou, Xiao-Nong; Bergquist, Robert

2017-05-04

Although the focus in the area of health research may be shifting from infectious to non-communicable diseases, the infectious diseases of poverty remain a major burden of disease of global health concern. A global platform to communicate and share the research on these diseases is needed to facilitate the translation of knowledge into effective approaches and tools for their elimination. Based on the "One health, One world" mission, a new, open-access journal, Infectious Diseases of Poverty (IDP), was launched by BioMed Central in partnership with the National Institute of Parasitic Diseases (NIPD), Chinese Center for Disease Control and Prevention (China CDC) on October 25, 2012. Its aim is to identify and assess research and information gaps that hinder progress towards new interventions for a particular public health problem in the developing world. From the inaugural IDP issue of October 25, 2012, a total of 256 manuscripts have been published over the following five years. Apart from a small number of editorials, opinions, commentaries and letters to the editor, the predominant types of publications are research articles (69.5%) and scoping reviews (21.5%). A total of 1 081 contributing authors divided between 323 affiliations across 68 countries, territories and regions produced these 256 publications. The journal is indexed in major international biomedical databases, including Web of Science, PubMed, Scopus and Embase. In 2015, it was assigned its first impact factor (4.11), which is now 2.13. During the past five years, IDP has received manuscripts from 90 countries, territories and regions across six continents with an annual acceptance rate of all contributions maintained at less than 40%. Content analysis shows that neglected tropical diseases (NTDs), followed by the "Big Three" (HIV/AIDS, malaria and tuberculosis) and infectious diseases in general comprise 88% of all publications. In addition, a series of 10 thematic issues, covering 118 publications

Liquid scintillators for radiocarbon dating in archaeology; Scintillateurs liquides pour l'evaluation de Page au moyen du radiocarbone en archeologie; Zhidkie stsintillyatory dlya radiouglerodnogo datirovaniya v arkheologii; Centelladores liquidos para la determinacion de edades con carbono-14 en arqueologia

Energy Technology Data Exchange (ETDEWEB)

Starik, I E; Rudenko, S I; Artem' ev, V V; Butomo, S V; Drozhzhin, V M; Romanova, E N

1962-01-15

5500 ans represente, pour des quantites de 40 et 70 ml de scintillateur, 65 et 25 ans respectivement. Les auteurs ont effectue des mesures sur des specimens archeologiques provenant de diverses regions de l'URSS. (author) [Spanish] Con el objeto de determinar mediante carbono radiactivo la edad absoluta de muestras arqueologicas, los autores utilizan un contador de centelleo sencillo con un fotomultiplicador, sin refrigeracion. Consiguen reducir la actividad de fondo empleando un blindaje formado por laminas de acero y de plomo, procediendo a una seleccion de los impulsos segun su amplitud y construyendo el detector con materiales seleccionados y ''purificados''. A partir del carbono contenido en la muestra arqueologica, se sintetiza etil benceno. Para efectuar las mediciones, se han utilizado de 18 a 72 ml de centelleador liquido, cantidad que corresponde de 3 a 12 g de carbono en la muestra. Empleando 40 ml de centelleador, la velocidad de recuento de la actividad de fondo y la del carbono contemporaneo (sin fondo) fueron respectivamente de 23,5 y 37 impulsos/min; con 70 ml, estas velocidades fueron de 28 y 57 impulsos/min. El error estadistico correspondiente a mediciones de 48 horas de duracion de muestras de 5500 anos de edad asciende a 65 y 35 anos cuando se emplean 40 ml y 70 ml de centelleador, respectivamente. Se midieron muestras arqueologicas procedentes de diversas regiones de la Union Sovietica. (author) [Russian] Dlya opredeleniya absolyutnogo vozrasta arkheologicheskikh obraztsov po radiouglerodu ispol'zuetsya prostoj stsintillyatsionnyj schetchik s odnim fotoumnozhitelem bez okhlazhdeniya. Snizhenie fona dostigaetsya primeneniem zashchity iz sloev stali i svintsa, amplitudnoj selektsii impul'sov i vyborom ''chistykh'' materialov dlya izgotovleniya detektora. Iz ugleroda, soderzhashchegosya v arkheologicheskom obraztse, sinteziruetsya ehtilbenzol. Pri izmereniyakh ispol'zovalos' ot 18 do 72 ml zhidkogo stsintillyatora, chto sootvetstvovalo vvedeniyu ot 3

Structured materials for catalytic and sensing applications

Science.gov (United States)

Hokenek, Selma

The optical and chemical properties of the materials used in catalytic and sensing applications directly determine the characteristics of the resultant catalyst or sensor. It is well known that a catalyst needs to have high activity, selectivity, and stability to be viable in an industrial setting. The hydrogenation activity of palladium catalysts is known to be excellent, but the industrial applications are limited by the cost of obtaining catalyst in amounts large enough to make their use economical. As a result, alloying palladium with a cheaper, more widely available metal while maintaining the high catalytic activity seen in monometallic catalysts is, therefore, an attractive option. Similarly, the optical properties of nanoscale materials used for sensing must be attuned to their application. By adjusting the shape and composition of nanoparticles used in such applications, very fine changes can be made to the frequency of light that they absorb most efficiently. The design, synthesis, and characterization of (i) size controlled monometallic palladium nanoparticles for catalytic applications, (ii) nickel-palladium bimetallic nanoparticles and (iii) silver-palladium nanoparticles with applications in drug detection and biosensing through surface plasmon resonance, respectively, will be discussed. The composition, size, and shape of the nanoparticles formed were controlled through the use of wet chemistry techniques. After synthesis, the nanoparticles were analyzed using physical and chemical characterization techniques such as X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Scanning Transmission Electron Microscopy- Energy-Dispersive Spectrometry (STEM-EDX). The Pd and Ni-Pd nanoparticles were then supported on silica for catalytic testing using mass spectrometry. The optical properties of the Ag-Pd nanoparticles in suspension were further investigated using ultraviolet-visible spectrometry (UV-Vis). Monometallic palladium particles have

Circulations in the Bay of Bengal and the Arabian Sea with Reference to Safe Disposal of Radioactive Wastes Near the Indian Coasts; Les Circulations dans les Eaux du Golfe du Bengale et de la Mer d'Oman et l'Elimination sans Danger des Dechets Radioactifs pres des Cotes Indiennes; 0426 0418 0420 0414 ; Circulaciones en el Golfo de Bengala e en el Mar Arabico con Relacion a la Evacuacion sin Riesgos de Desechos Radiactivos Frente al Litoral Indio

Energy Technology Data Exchange (ETDEWEB)

Rama Sastry, A. A. [Meteorological Office, Poona 5 (India)

1960-07-01

dannyh, sobrannyh razlichnymi jekspedicijami v Indijskom okeane, izuchaetsja fizicheskaja okeanografija v rajone k severu ot jekvatora. Kak v Bengal'skom zalive, tak i v Aravijskom more na glubine do 200 metrov imeetsja po krajnej mere tri razlichnyh vodnyh sloja. V vidu ochen' sil'noj rastvoritel'noj sposobnosti vod Bengal'skogo zaliva poverhnostnye vody mogut byt' podrazdeleny eshhe na neskol'ko kategorij. Po gorizontal'nomu raspredeleniju razlichnyh okeanograficheskih parametrov daetsja cirkuljacija vodnyh mass na razlichnyh urovnjah do 150 metrov vdol' indijskogo poberezh'ja ; jeto zhe otnositsja i k vodnym massam do 500 metrov po vertikal'nomu secheniju. Uroven' nepodvizhnyh vod, kak kazhetsja, nahoditsja vyshe 500 metrov i menjaetsja kak po ploshhadi, tak i po vremeni. Smeshenie vod vyvoditsja iz otnoshenija T-S (vremja-ploshhad'). Privodjatsja sezony povyshenija i ponizhenija urovnja vody vdol' poberezh'ja i rassmatrivaemogo rajona. Intensivnost' povyshenija urovnja vody vdol' poberezh'ja bolee vyrazhena i v techenie jetogo perioda proishodit polnoe smeshenie sloev vody na priberezhnoj otmeli. Glubokovodnye massy razdeljajutsja na vody jekvatorial'noj chasti Indijskogo okeana, antarkticheskie promezhutochnye sloi vody sovmestno s vodami Krasnogo morja i na neznachitel'nuju chast' vod central'noj chasti Indijskogo okeana, glubokovodnye massy Indijskogo okeana i antarkticheskie donnye vody. Daetsja raspredelenie jetih vodnyh mass, a takzhe cirkuljacija glubinnyh vodnyh sloev k severu ot jekvatora. Kak kazhetsja, za poslednie 60 let antarkticheskie donnye vody prodvigajutsja dalee k severu ot jekvatora kak v Bengal'skom zalive, tak i v Aravijskom more. V svjazi s jetim nabljudaetsja ponizhenie solenosti kak v Bengal'skom zalive, tak i v Aravijskom more. V zakljuchenie predlagetsja programma dal'nejshih okeanograficheskih issledovanij v svjazi s bezopasnym udaleniem radioaktivnyh othodov, v chastnosti v Aravijskoe more. (author)

Improved Oxidation Resistance of Zirconium Resulting from Addition of Small Amounts of Copper; Amelioration de la Resistance a l'Oxydation du Zirconium par de Faibles Additions de Cuivre; Povyshenie soprotivlyaemosti k okisleniyu tsirkoniya posle dobavlenij nebol'shikh kolichestv medi; Aumento de la Resistencia del Circonio a la Oxidacion por Agregado de Pequenas Cantidades de Cobre

Energy Technology Data Exchange (ETDEWEB)

Loriers, H.; Darras, R.; Baque, P. [Centre d' Etudes Nucleaires de Saclay (France)

1966-02-15

chastnosti splav s 2,5% medi, vidimo, predstavljajut interes v kachestve materialov dlja pokrytija ili konstrukcionnyh materialov dlja toplivnyh jelementov reaktorov tipa tjazhe- laja voda - uglekislyj gaz. Korrozija cirkonija, vyzyvaemaja uglekislym gazom, svoditsja po sushhestvu k okisleniju, v techenie kotorogo voznikajut dva processa: 1) sozdanie monoklinicheskogo cirkonievogo sloja, cherez kotoryj kislorod rasseivaetsja putem migracii anionnyh ''dyrok''; 2) rastvorenie i diffuzija kisloroda, kotoryj protekaet putem ego vvedenija v metall. Sochetanie gravimetricheskih dannyh i izmerenij plotnostej sloev okisi pozvoljaet opredelit' dva sootvetstvujushhih kojefficienta diffuzii. Jetot raschet po analogii raspro- stranjaetsja na sluchaj s dvojnymi, medno-cirkonievymi splavami pri koncentracii medi nizhe ili ravnoj 4 ves%. Sravnenie poluchennyh rezul'tatov pokazyvaet, chto kojefficient diffu- zii kisloroda v obrazovavshemsja sloe okisi umen'shaetsja s uvelicheniem kolichestva medi v rassmatrivaemom splave; s drugoj storony, sootvetstvujushhij kojefficient diffuzii kislo- roda v splave, esli on neskol'ko izmenen pri 600 Degree-Sign S, umen'shaetsja pri 700 Degree-Sign S s uvelicheniem kolichestva medi do 2,5%. Povyshenie soprotivljaemosti k okisleniju, svjazannoe s zamedle- niem processov diffuzii, dostigaetsja, v chastnosti, v rezul'tate prodolzhitel'nogo sohrane- nija kinetiki parabolicheskogo tipa, v to vremja kak v sluchae s nesoedinennym cirkoniem ili s drugimi splavami rastreskivanie sloja okisi v rezul'tate otslaivanija bystro privodit k linejnoj kinetike okislenija. (author)

Some Applications of Short-Lived Radioisotopes in the Study of Metals; Applications Diverses des Radioelements de Courte Periode dans l'Etude des Metaux; РАЗЛИЧНЫЕ ПРИМЕНЕНИЯ КОРОТКОЖИВУЩИХ РАДИОЭЛЕМЕНТОВ ПРИ ИССЛЕДОВАНИЯХ МЕТАЛЛОВ; Aplicaciones de los Radioelementos de Periodo Corto en el Estudio de los Metales

Energy Technology Data Exchange (ETDEWEB)

Kohn, A. [Institut de Recherches de la Siderurgie, Saint-Germain-en-Laye (France)

1963-03-15

despues de la colada. En muchos de estos lingotes, se registraron corrientes de conveccion de intensidad suficiente para distribuir el oro por gran parte del volumen del lingote una hora despues de terminada la colada. (author) [Russian] V jetom doklade izlagaetsja nekotorye tipichnye vidy primenenija korotkozhivushhih radiojelementov pri issledovanii metallov. Razrabotan prostoj metod aktivacionnogo analiza dlja opredelenija soderhanija lantana v razlichnyh markah stali, k kotoroj vo vremja plavki dobavljaetsja neznachitel'noe kolichestvo neochishhennoj smesi redkozemel'nyh jelementov. Issledovalos' povedenie mysh'jaka v period okislenija zheleza s cel'ju izuchit', kak vedut sebja neznachitel'nye kolichestva soderzhashhegosja v zheleze mysh'jaka v jetot period. S pomoshh'ju avtoradiografii bylo ustanovleno prezhde vsego znachitel'noe obogashhenie mysh'jakom poverhnosti razdela metall-okis'. V rezul'tate primenenija metoda, zakljuchajushhegosja v aktivirovanii okislennyh obrazcov v jader- nom reaktore i rastvorenii obrazujushhihsja sloev tolshhinoj v neskol'ko mikron, predstavilos' vozmozhnym izuchit' dannoe javlenie v kachestvennom otnoshenii. Udalos' proverit', chto mysh'jak koncentriruetsja v metalle rjadom s poverhnost'ju razdela, gde ego koncentracija mozhet v 30 - 40 raz prevyshat' pervonachal'noe soderzhanie primesi. S pomoshh'ju avtoradiografii issledovalsja prirost metallicheskih kristallov, s uchetom togo, chto tverdoe telo bolee bedno legirujushhimi jelementami po sravneniju s rasplavom, iz kotorogo ono obrazuetsja. Jeto issledovanie kasalos' medlenno ohlazhdaemyh splavov alljuminija i medi, kotorye zatem poluchali zakalku v processe zatverdenija. Issledovanie pozvolilo vyjavit' konfiguraciju metallicheskih kristallov na razlichnyh stadijah ih prirosta i ustanovit' zavisimost' processa zatverdenija ot izmenenija temperatury splava, izmerjaemoj s pomoshh'ju termopary. Izuchenie konvektivnyh tokov v bol'shih slitkah dlja pokovki imelo cel'ju podtverdit' nalichie

Indirect Determination of Half-Lives of Short-Lived Fission Gases Using a Gas Flow Method; Determination Indirecte des Courtes PeRiodes de Produits de Fission Gazeux, par une Methode a Courant Gazeux; 041a 041e 0421 0412 0415 041d 041d 041e 0415 041e 041f 0420 0415 0414 0415 041b 0415 041d 0418 0415 041f 0415 0420 0418 041e 0414 041e 0412 041f 041e 041b 0423 0420 0410 0421 041f 0410 0414 0410 041a 041e 0420 041e 0422 041a 041e 0416 0418 0412 0423 0429 0418 0425 0413 0410 0417 041e - 041e 0411 0420 0410 0417 041d 042b 0425 041f 0420 041e 0414 0423 041a 0422 041e 0412 0414 0415 041b 0415 041d 0418 042f 0421 0418 0421 041f 041e 041b 042c 0417 041e 0412 0410 041d 0418 0415 041c 041c 0415 0422 041e 0414 041e 0412 0413 0410 0417 041e 0412 041e 0413 041e 041f 041e 0422 041e 041a 0410 ; Determinacion Indirecta del T 1/2 de los Cases de Fision de Periodo Corto por un Metodo de Circulacion

Energy Technology Data Exchange (ETDEWEB)

Patzelt, P.; Herrmann, G. [Institut fuer Anorganische Chemie und Kernchemie der Universitaet Mainz, Mainz, Federal Republic of Germany (Germany)

1965-07-15

.87 {+-} 0.15 min; {sup 138}Xe, 14.5 {+-} 0.5 min; {sup 139}Xe, 40.4 {+-} 1.3 s: {sup 140}Xe, 13.33 {+-} 0.27s; {sup 141}Xe, 1.70 {+-} 0.05s; {sup 142}Xe, 1.15 {+-} 0.04s- y {sup 143}Xe, 0.96 {+-} 0.02s. Los periodos de semidesintegracion se determinaron extrapolando las curvas correspondientes de desintegracion beta o las curvas de atenuacion de los picos gamma. Los datos enumerados representan los promedios resultantes de una serie de mediciones' a los que se ha aplicado un coeficiente de ponderacion W{sub i} Tilde-Operator 1/o{sup 2}. Todos los computos se rtan realizado en el centro de calculo electronico de la Universidad de Maguncia. (author) [Russian] Poskol'ku issledovanie raspredelenija zarjadov pri jadernom delenii trebuet opredelenija pervichnyh vyhodov otdel'nyh produktov delenija, kotorye v bol'shinstve sluchaev javljajutsja libo korotkozhivushimi sami po sebe, libo proishodjat iz korotkozhivushhih predshestvennikov, to neobhodimo provesti ochen' bystroe i jeffektivnoe razdelenie sosednih chlenov cepochki produktov delenija. Ispol'zuja chrezvychajno vysokuju jemanacionnuju sposobnost' nekotoryh uranovyh soedinenij, naibolee legko razdelit' gazoobraznye produkty delenija v bolee chem 12 cepochkah produktov delenija. Raschety vyhodov, a takzhe jeffektivnaja jemanacionnaja sposobnost' tolstyh sloev misheni mogut, odnako, ispytyvat' sushhestvennoe vlijanie so storony dannyh o periode poluraspada gazov. Pojetomu periody poluraspada izotopov kriptona i ksenona (Kr{sup 89}-Kr{sup 93} i Xe{sup 137}- X{sup 143}) {sup y}li opredeleny s bol'shoj tochnost'ju pri ispol'zovanii metoda skorosti potoka sovmestno s uluchshennym metodom zarjazhennogo jelektroda. Izmerenija proizvodilis' posredstvom aktivnogo otlozhenija dolgozhivushhih produktov raspadah na jelektrodah. ' Skorost' potoka, vremja obluchenija, period ohlazhdenija i sistema scheta izbiralis' takim obrazom, chtoby izmerenija otdel'nyh dochernih produktov okazalis' naibolee blagoprijatnymi. V nekotoryh sluchajah v

The Technology and Applications of Large Fission Product Beta Sources; Technologie et applications des grandes sources beta de fission; Tekhnologiya i primenenie krupnykh istochnikov beta-izluchenij, ispuskaemykh produktami deleniya; Tecnologia y utilizacion de los productos de fision como fuentes de irradiacion beta de elevada intensidad

Energy Technology Data Exchange (ETDEWEB)

Silverman, Joseph [Radiation Applications Incorporated (United States)

1960-07-15

poverkhnostnykh sloev plastmassy i tekstilya. 2. Massivnye, prochnye, inertnye, bezopasnye i nedorogie istochniki beta-izluchenij mogut stroit'sya putem nadlezhashchego rasshireniya sushchestvuyushchikh tekhnicheskikh ustanovok. Osobenno mnogoobeshchayushchimi predstavlyayutsya zaklyuchayushchie v sebe istochniki steklyannye ampuly. 3. Podschety pogloshcheniya beta-izluchenij pokazyvayut, chto predstavlyaetsya vozmozhnym skonstruirovat netochechnye istochniki s dostatochno vysokim kpd ispol'zovani ya moshchnosti, dokhodyashchim do 20%. Byli vyvedeny uravneniya i sostavleny krivye dayushchie dozirovku i kpd ispol'zovani ya beta-izluchenij v zavisimosti ot konfiguratsii izluchatelya, sostava veshchestv i materialov, vkhodyashchikh v konstruktsiyu istochnika i misheni. Dlya proverki pravil'nosti ehtikh podschetov v nastoyashchee vremya provoditsya ehksperimental'na ya programma. 4. Izuchenie proizvodstvennoj sebestoimosti ukazyvat, chto beta-izlucheniya, ispuskaemye produktami deleniya, mogut konkurirovat' s drugimi istochnikami izluchenij. (author)

Experimental studies of some of the physical features of beryllium-moderated intermediate reactors; Etude experimentale de quelques particularites physiques des reacteurs a neutrons intermediaires, ralentis au beryllium; Ehksperimental'ny e issledovaniya nekotorykh fizicheskikh osobennostej promezhutochnykh reaktorov s berillievym zamedlitelem; Estudios experimentales de algunas caracteristicas fisicas de los reactores intermedios moderados con berilio

Energy Technology Data Exchange (ETDEWEB)

Lejpunskij, A I; Kuznetsov, V A; Artyukhov, G Ya; Mogil' ner, A I; Prokhorov, Yu A; Steklovski, V M; Chernov, L A [Akademiya Nauk, Moskva, Union of Soviet Socialist Republics (Russian Federation)

1962-03-15

la evaluacion de la eficacia de los cilindros compensadores giratorios distribuidos en el limite entre el cuerpo y el reflector. (author) [Russian] Doklad posvyashchen obzoru nekotorykh ehksperimen-tal'nykh rezul'tatov, poluchennykh na stende PF-4, prednaznachennom dlya detal'nogo issledovaniya fizicheskikh osobennostej reaktorov, rabotayushchikh na nejtronakh promezhutochnykh ehnergij. Aktivnye zony i otrazhateli razlichnykh kriticheskikh sborok predstavlyali soboj plotnuyu upakovku stal'nykh ili alyuminievykh trub, v kotorykh pomeshchalis' diski iz razlichnykh materialov. Kombinatsiya diskov urana (90%-nogo obogashcheniya) i zamedlyayushchikh materialov v razlichnoj proportsii, a takzhe vvedenie v otrazhatel' zamedlyayushchikh sloev razlichnoj tolshchiny, pozvolilo menyat' spektr nejtronov, proizvodyashchikh delenie, v ochen' shirokikh predelakh. V doklade privedeno opisanie stenda i ego otdel'nykh uzlov. Analiziruetsya sravnitel'naya ehffektivnost' vnutrennego i vneshnego zamedleniya dlya reaktorov s ochen'malym otnosheniem yader zamedlitelya i urana v aktivnoj zone. Ehksperimenty pokazyvayut, chto dazhe v sluchae tolstykh zamedlyayushchikh otrazhatelej maloe razbavlenie urana zamedlitelem (otnoshenie yader berilliya i urana-235 {partial_derivative}Be/{partial_derivative}U{sup 235}{approx_equal}1) privodit k vozrastaniyu kriticheskoj massy. Znachitel'noe mesto v doklade udeleno analizu geterogennykh ehffektov v promezhutochnykh reaktorakh. Pokazano, chto dlya reaktora s {partial_derivative}Be/{partial_derivative}U{sup 235}= 30+40, vysokoobogashchenny j uran v razlichnykh tolshchinakh ot 0,023 g/sm{sup 2} do 32 g/sm{sup 2} okazyvaet odinakovoe vliyanie na reaktiv-nost' sistemy. Analiziruyutsya prichiny, privodyashchie k kompensatsii ehffekta ehkranirovki nejtronnogo potoka tolstymi sloyami urana. V doklade privoditsya interesnyj fakt vozrastaniya ehffektivnosti urana vblizi po- gloshchayushchikh sterzhnej, ehksperimental'n o obnaruzhennyj v sbor kes {partial

Excitation of Neutron Waves by Modulated And Pulsed Sources; Excitation d'Ondes Neutroniques au Moyen de Sources Modulees et Pulsees; Vozbuzhdenie nejtronnykh voln s pomoshch'yu modulirovannykh i impul'snykh istochnikov; Excitacion de Ondas Neutronicas Mediante Fuentes Moduladas y Pulsadas

Energy Technology Data Exchange (ETDEWEB)

Perez, R. B.; Booth, R. S. [University of Florida, Gainesville, FL (United States)

1965-10-15

jadernyh svojstvah, predstavljajushhih interes. Pri provedenii jeksperimentov v kachestve zamedlitelja ispol'zovali grafit. Ispol'zovali dva razlichnyh istochnika teplovyh nejtronov. V odnom sluchae nejtrony s jenergiej 14 Mjev, poluchennye s pomoshh'ju uskoritelja Kokrofta-Uoltona, byli termalizovany v bake, soderzhashhem neskol'ko sloev zheleza, svinca i grafita, pogruzhennyh v vodu. Pozdnee s po* moshh'ju imejushhegosja vo Floridskom universitete uskoritelja Van de Graafa moshhnost'ju 4 Mjev byli polucheny nejtrony s jenergiej 29 kjev iz reakcii ( Li -r) , kotorye byli termalizovany v neskol'kih djujmah parafina. V oboih sluchajah ionnye puchki mogli byt' sinusoidal'no modulirovannymi ili pul'sirujushhimi. Rezul'taty analiza Fur'e, provedennogo s medlennymi impul'sami, prekrasno soglasujutsja s rezul'tatami, poluchennymi pri sinusoidal'nom vozbuzhdenii voln. Issleduemye chastoty byli v diapazone ot nulja do 1200 gc. V rezul'tate aproksimacii jeksperimental'nyh dannyh sposobom naimen'shih kvadratov s primeneniem uravnenij (4) i (5) byli polucheny sledujushhie rezul'taty: B{sup (0)} = B{sup 2}{sub Up-Tack} + a{sub 1}/L{sub 0} = (6.6 {+-} 0.1) 10{sup -3} (cm{sup -2}) (4) B{sup (1)} = a{sub 2}/D{sub 0} = (4.38 {+-} 0.2) 10{sup -6} (cm{sup -2}) (5) B{sup (2)} = {Sigma}{sub {gamma}} H{sub 0{gamma}}/ Empty-Set {sub {gamma}{gamma}} = (2.5 {+-} 0.2) 10{sup -10} ({gamma} = 0, 1, 2, .....10) (6) B{sup 2}{sub Up-Tack} = poperechnyj laplasian (cm{sup -2}) = 5.96 x 10{sup -3} cm{sup -2} otnosjatsja k matrichnym jelementam diffuzionnyh i termalizacionnyh operatorov. S pomoshh'ju uravnenija (5) opredeleno, chto znachenie D{sub 0} = (2.2 {+-} 0.1) x 10{sup 5} cm{sup 2}/sek-l soglasuetsja s obychnymi izmerenijami impul'snyh nejtronov (5). Teoreticheskie raschety s ispol'zovaniem razlichnyh modelej jadra takzhe soglasujutsja s jeksperimental'nymi rezul'tatami. (author)