UK PubMed Central (United Kingdom)

ObjectivesWe undertook a meta-analysis to assess outcomes for drug-eluting (DES) and bare metal stents (BMS) in percutaneous coronary intervention (PCI) for unprotected...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundPresumptive treatment of all febrile patients with anti-malarials leads to massive over-treatment. The aim was to assess the effect of implementing malaria rapid diagnostic...Full Text Available

Science.gov (United States)

Feb 23, 2001 ... Florida, as an F-16 weapons separation engineer with .... new era of space-based research aboard the International Space. Station. ..... the Web at: http://www. aiaa.org/calen- dar/index.hfm?cal=1&cfp=1 ...

International Nuclear Information System (INIS)

(1 Oct 1979). German Democratic Republic Alekseeva, OK Onishchuk, VA

Science.gov (United States)

green (both light and dark tones) and purple, bare areas are seen in ...... spatial scale continue to plague such efforts. Knowledge of the spatial ...

Science.gov (United States)

and palladium silicides (Pd,Si) with a total. AES intensity ratio of Pd to Si of 35/65. Scanning Electron Microscopy. (SEM') of the Pd region shows that ...

Energy Technology Data Exchange (ETDEWEB)

One- and two-dimensional long-period superstructures (LPS), based on the L1{sub 2} substructure, are systematically investigated for the noble metal-palladium alloys Cu-Pd, Ag-Pd and Au-Pd with first-principles methods. Notwithstanding the fact that the experimental phase diagrams of these systems yield totally different features, quite similar behaviour with respect to formation of low temperature ordered LPS-phases (Cu{sub 3}Pd: LPS 3, Ag{sub 3}Pd: LPS 3, Au{sub 3}Pd: LPS 2; {l_brace}Cu, Au{r_brace}Pd{sub 3}: L1{sub 2}, AgPd{sub 3}: not a ground state) is predicted. As a lever between via LDA obtained formation enthalpies and a thorough ground state scan, the cluster expansion method in conjunction with a genetic algorithm provides adequate means for the extraction of effective interactions, which also allow for an ...

International Nuclear Information System (INIS)

New ternary compounds on the ytterbium base YbPd_2Ge, YbPd_2Si, YbPdGe, YbPdSi, YbPtGe, YbPd_2Ge_2 and known compound YbPdSi_2 were obtained and investigated. Results of measuring the electric resistivity and magnetic susceptibility in the 4.2-300 K range are presented. It is found that YbPdGe, YbPtGe, YbPd_2Ge at low temperatures have magnetic phase transitions, investigations of which testify to dominant contribution of ferromagnetic ordering. The investigation results testify also to substantial effect of ytterbium crystalline environment on the physical properties of compounds under study.

British Library Electronic Table of Contents (United Kingdom)

Digital topographic models are the foundation of more advanced modeling applications and ultimately inform planning and decision making in many fields. Despite this, the error associated with these models and derived attributes is commonly overlooked. Little attention has been given in the scientific literature to the benefits gained from having less error in a model or to the corresponding cost associated with reducing model error by choosing one product over another. To address these gaps in knowledge we evaluated the error associated with five digital elevation models (DEMs) and derived attributes of slope and aspect relative to the same attributes derived from LiDAR data. We also estimated the acquisition and processing costs per square kilometer of the five test models and the LiDAR m...

British Library Electronic Table of Contents (United Kingdom)

Palladium silicide was formed on the sol-gel derived SiO2 supported Pd catalysts prepared by ion-exchange method (Pd/SiO2-SG-ion). However, the catalysts exhibited superior performances than commercial SiO2 supported ones in liquid-phase semihydrogenation of phenylacetylene. It was probably due to an inhibition of a product of styrene, which is adsorbed on the surface of Pd, more strongly on Pd/SiO2-SG in which Pd is electron-deficient as shown by larger binding energy from XPS results.

Science.gov (United States)

Ti-Ag and Ti-Pd-Ag solar cell contacts structure and degradation dependence on high temperature and humidity environmental exposure

International Nuclear Information System (INIS)

... magnetic susceptibility magnetization monocrystals neutron diffraction

International Nuclear Information System (INIS)

In this paper, some results of the indoor radon concentration measurements are presented. Kodac track detectors LR 115, bare and in a cup were used for these measurements. Average winter/summer ratio was determined for the town of interest. (author). 5 refs, 1 fig., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

A method for the determination of different ''bare'' characteristics of the one-particle motion and one-particle basis in magic nuclei is described. The method is based on separating out the mixing with phonons from the phenomenological one-particle characteristics. By means of a generalization of the procedure for localization of the mass operator, relations linking the bare and phenomenological characteristics are obtained. The radial dependence of these characteristics in finite nuclei and the influence of the quasiparticle--phonon interaction on the phenomenological characteristics are studied. Calculations are performed for the neutrons in /sup 208/Pb.

KoreaScience (Korea)

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No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

We have demonstrated in this work (1) that methane is readily activated at mild conditions (100{degree}C, 1 torr) over a relatively noble metal, Pd. This was observed using a stepped and kinked Pd(679) crystal (1), and other crystal faces are now being investigated to establish whether the cracking of the C-H bond of methane on Pd is structure sensitive or structure insensitive. Oxygen chemisorption is extremely structure sensitive: weakly bonded, highly reactive oxygen overlayers form on Pd(100) surface (2), while strongly bonded, moderately reactive oxygen overlayers form on Pd(111) and Pd(679). Reaction of the weakly bonded oxygen with surface carbide gives rise to CO{sub 2} over clean Pd(100) but to CO over halogen-doped Pd(100) (3--5). The effect of halogens is primarily ensemble-controlling, or oxygen-supply ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

British Library Electronic Table of Contents (United Kingdom)

The performance of Ag-promoted Pd/Al2O3 catalysts, which were prepared by the selective deposition of Ag onto Pd using a surface redox (SR) method, during acetylene hydrogenation was compared with that of catalysts prepared by impregnation. The Pd surface was more effectively modified with Ag added by SR, even when small amounts of Ag were added. The catalyst prepared by SR showed a higher ethylene selectivity than the one prepared by impregnation, because SR allowed both the preferential deposition of Ag on the low-coordination sites of Pd and a greater electronic modification of Pd by Ag.

Energy Technology Data Exchange (ETDEWEB)

Growth mechanisms and thermal stability of ion-beam-induced epitaxial Pd/sub 2/Si films are investigated using Rutherford backscattering and channelling techniques. Epitaxial growth of Pd/sub 2/Si films was observed at room temperature by argon ion implantation into as-deposited Pd/Si(111) structures and furnace-annealed Pd/sub 2/Si(polycrystalline)/Pd/sub 2/Si(epitaxial)/Si(111) structures. Some additional experiments to check the growth mechanisms are also presented, in which the implantation energies, substrate orientations and dose rates were changed. Finally, the stability of the ion-beam-induced epitaxial Pd/sub 2/Si films on subsequent furnace annealing is studied.

Energy Technology Data Exchange (ETDEWEB)

The a.c. susceptibility and high field magnetization of TbRh{sub 2-x}Pd{sub x}Si{sub 2} and TbRu{sub 2-x}Pd{sub x}Si{sub 2} compounds were investigated up to 140 kOe. The (T, x) magnetic phase diagrams were determined. For both systems, an increase in the Pd content causes a decrease in the Neel temperature and changes the magnetization curves. (orig.)

International Nuclear Information System (INIS)

Aerodynamic sound derived from bluff bodies can be considerably reduced by flow control. In this paper, the authors propose a new method in which porous material covers a body surface as one of the flow control methods. From wind tunnel tests on flows around a bare cylinder and a cylinder with porous material, it has been clarified that the application of porous materials is effective in reducing aerodynamic sound. Correlation between aerodynamic sound and aerodynamic force fluctuation, and a surface pressure distribution of cylinders are measured to investigate a mechanism of aerodynamic sound reduction. As a result, the correlation between aerodynamic sound and aerodynamic force fluctuation exists in the flow around the bare cylinder and disappears in the flow around the cylinder with porous material. Moreover, the aerodynamic force fluctuation of the cylinder with porous material is less than that of the bare cylinder. ...

Science.gov (United States)

The title compounds were prepared by arc-melting of the elemental components. Whereas NdPdSi and SmPdSi are already present after the arc-melting, alpha-GdPdSi and alpha-TbPdSi are formed only during the annealing at 800 degC. The four compounds crystallize with the recently reported alpha-YbAuGe type structure, which was refined for alpha-GdPdSi: Pnma, a=2108.0(4) pm, b=433.9(1) pm, c=745.6(1) pm, Z=12, R=0.026 for 1447 structure factors and 62 variable parameters. The lanthanoid atoms are situated between two-dimensionally infinite nets of condensed, puckered hexagons formed by alternating palladium and silicon atoms, with Pd-Si distances varying between 251 and 262 pm. In the third dimension these nets are linked via weak Pd-Pd (300 pm), Pd-Si (283 pm), and Si-Si bonds (261 pm). The refinements of the occupancy ...

Energy Technology Data Exchange (ETDEWEB)

The initial growth process and surface structure of thin Pd(silicide) films on clean Si(111)-7x7 surfaces have been studied by low energy ion scattering (ISS) and LEED-Auger techniques. Considerable reaction between Pd and Si at room temperature is observed to extend up to 25 ML thickness of deposited Pd. Heat treatment of the room temperature film produced epitaxial silicide Pd/sub 2/Si(0001) films covered with the accumulated elementary Si layers of 1-2 ML thickness. Deposition of 1/3 ML Pd onto a heated substrate gives a Pd-embedded ordered surface of Si(111)-..sqrt..3x..sqrt..3R30/sup 0/, the feature being similar to the cases of Ag, Au/Si(111) systems.

Energy Technology Data Exchange (ETDEWEB)

Pd/Ag alloy hollow spheres have been synthesized in ethylene glycol solution by the solvothermal method and have been characterized extensively. TEM results have revealed the formation of Pd/Ag hollow spheres. Moreover, HRTEM results confirmed the formation of Pd/Ag alloy spheres, where the lattice fringe spacing is 0.229 nm corresponding to the (111) plane of Pd/Ag alloy. SEM, XRD and UV-vis results have further suggested the formation of alloy hollow spheres. The preliminary results showed the reaction time may be an importance factor influencing the formation of Pd/Ag alloy hollow spheres.

Energy Technology Data Exchange (ETDEWEB)

The behaviour of bare aluminium is studied in atmospheric exposure at 11 natural testing stations with salinity levels ranging between 2.1 and 684 mg Cl''- m''-2 d''-1. In atmospheres of low or moderate aggressivity aluminium behaves as a passive material, though the insignificant corrosion that is produced is sufficient to spoil its appearance. In contrast, at salinity levels of 50 mg Cl''- m''-2 ''-1 or above, aluminium is susceptible to pitting corrosion even in the first year of atmospheric exposure, or in the second year at salinities of {<=} 10 mg Cl''- m''-2 d''-1. For comparative purposes, results are included for aluminium protected with an anodic film of 28 {mu}m thickness exposed at the same testing stations. A 28 {mu}m anodic film, correctly sealed, prevents the risk of localised ...

Science.gov (United States)

was to mount Pd-Ag terminated MLCCs onto gold plated mounting pads of a ... to protect against incorrect shipment of pure tin-plated MLCCs when Pd-Ag ...

Energy Technology Data Exchange (ETDEWEB)

Combining in situ Rutherford backscattering and electrical transport measurements on low-temperature hydrogen-implanted amorphous Pd/sub 80/Si/sub 20/ films, we have studied the correlation between the hydrogen content and the resistivity.

International Nuclear Information System (INIS)

The applicability of in situ, real-time RBS is demonstrated by characterizing the growth of thin Pd_2Si films on Si left angle 111 right angle substrates using isothermal as well as non-isothermal annealing. In contrast to the currently fashionable in situ ramped resistance technique, it is possible to extract the activation energy from a single run with a constant heating rate. The results, which are in excellent agreement with the literature, will be compared for isothermal annealing, fitting an appropriate model for the growth process to data from a single run and a Kissinger-like analysis with different ramp rates. In situ, real-time RBS was also used to study marker motion during CrSi_2 formation in the Si left angle 100 right angle /Pd_2Si/Cr system. It is possible to distinguish between the following mechanisms: (1) CrSi_2 formation via dissociation of the Pd_2Si at the Pd_2Si/Cr interface and ...

UK PubMed Central (United Kingdom)

Pneumatic dilation (PD) is an effective treatment for achalasia cardia. Outcome of PD, however, varies among different studies. Recently, some groups started considering laparoscopic myotomy to be competitive...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

This paper reported on a study in which partial discharge (PD) measurements were performed on 6 underground transmission cable circuits to determine the effectiveness of PD measurements on fluid fill cables. The cables were between 37 and 56 years old. PD activity was detected from the terminations of H11L and H3L Cable 2. However, for cables from H3L Basin TS to Mill Street junction, PD activity was detected originating from within the main cable insulation.

International Nuclear Information System (INIS)

... susceptibility magnetization magnetoresistance monocrystals order-disorder

Science.gov (United States)

... where the total palladium concentration equals that of silicon, the concentrations of palladium associated with various palladium silicides (Pd(x)Si , ...

Energy Technology Data Exchange (ETDEWEB)

Attempts to synthesize YPd[sub 2]Si-type representatives LnPd[sub 2]Al were successful only with Ln triple bond Ce, Pr, Nd. This orthorhombic structure (oP16; space group Pnma) is an ordered variant of the Fe[sub 3]C type. Only NdPd[sub 2]Al undergoes magnetic ordering above 2 K. (orig.)

International Nuclear Information System (INIS)

In Ce(Ru_1_-_xPd_x)_2Si_2 the dilution of the transition metal leads to strong electronic effects resulting in the disappearance and the appearance of long-range magnetic order in CePd_2Si_2 and CeRu_2Si_2, respectively. ((orig.)).

Energy Technology Data Exchange (ETDEWEB)

Hydrocarbon synthesis during CO hydrogenation over Pd/M-ZSM5 (M=H,Na,La) and Pd/SiO/sub 2/ has been investigated. Overall activity depended on the cation-exchanged form of the support and decreased in the order Pd/La-ZSM5 = Pd/Na-ZSM5 > Pd/H-ZSM5 > Pd/SiO/sub 2/. The zeolite-supported catalysts showed high selectivity towards saturated C/sub 2/-C/sub 6/ hydrocarbons, whereas Pd/SiO/sub 2/ favored methanol production. Increasing temperature and H/sub 2//CO feed ratio led to higher reaction rates, lower yields of C/sub 2/-C/sub 6/ products, and increased lighter hydrocarbons. A mechanical mixture of Pd/SiO/sub 2/ and Na-ZSM5 showed similar product distribution as Pd/Na-ZSM5. Infrared spectra of the catalysts under reaction conditions indicate the presence of adsorbed oxygenates on the zeolite. ...

UK PubMed Central (United Kingdom)

G6PD activity was assayed in 20 Sardinian heterozygotes for G6PD deficiency and related to that of LDH and MDH. One of these heterozygotes showed a deficient phenotype in all her follicles, while the...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In this first quarterly technical report for DOE Contract No. DE-AC22-87PC79654, a description of the background, technology, and application is provided. The design and fabrication of advanced combustion chambers were completed during this period. Initial testing on both the bare metal and refractory lined advanced chambers were initiated. The units were tested initially with gas but primarily with coal. A Pittsburgh No. 8 pulverized coal was used for these test activities. Both advanced chambers pulsed well.

Energy Technology Data Exchange (ETDEWEB)

This document is an addendum to the 1996 Gunnison Monitoring Report for the Gunnison, Colorado, Wetlands Mitigation Report, dated July 1997. The purpose of this addendum is to: (1) modify how information on plant height and plant species criteria are presented; and (2) provide more detailed information regarding the evaluation of the bare ground criteria at the Camp Ketle site. The information in this addendum is provided at the request of the Bureau of Land Management to aid in future monitoring and evaluation of the wetland mitigation sites.

International Nuclear Information System (INIS)

The transformation of Pd/Si to Pd_2Si/Si is studied using Auger electron spectroscopy over a wide temperature range of 370-1020 K. The Pd film gets totally converted to Pd_2Si upon annealing at 520 K, and beyond 570 K, Si starts segregating on the surface of silicide. It is found that the presence of surface oxygen influences the segregation of Si. The time evolution study of Si segregation reveals that segregation kinetics is very fast and the segregated Si concentration increases as the temperature is increased. Scanning electron microscopy measurements show that Pd_2Si is formed in the form of islands, which grow as the annealing temperature is increased.

International Nuclear Information System (INIS)

Inert markers (evaporated tungsten and silver) were used in growth studies of silicides formed both by thermal annealing and by ion mixing in the Ni/Si, Pd/Si, and Cr/Si systems. The markers were initially imbedded inside silicides and backscattering spectrometry was used to determine the marker displacement after different processing conditions. The results obtained in thermal annealing are quite consistent with that found in previous investigations. Ni is the dominant diffusing species in Ni_2Si, while Si is the diffusing species in CrSi_2. In Pd_2Si, both Pd and Si are moving species with Pd the faster of the two. In contrast, in growth of silicides by ion irradiation Si is the faster diffusing species in all three systems.

Energy Technology Data Exchange (ETDEWEB)

Isotherms have been measured for H(D){sub 2}(g) solution in crystalline Pd{sub 9}Si{sub 2} in the temperature range from 235 to 373 K. The solubilities are significant, e.g., at 1.0 MPa (298 K), (H/Pd) = 0.052 or Pd{sub 9}Si{sub 2}H{sub 0.47}, however, there is no indication of hydride phase formation even down to 235 K at 1.0 MPa. The thermodynamic values for hydrogen solutions at infinite dilution of hydrogen are {Delta}H{degrees}{sub H}= -11.9 kJ/mole {1/2}H{sub 2} and {Delta}S{degrees}{sub H} = -50 J/K mole {1/2}H{sub 2}. The former is more negative than for Pd-H{sub 2} and the latter is somewhat more positive; but generally the values are not that different from Pd-H{sub 2}. The isotope effect is similar to that found for Pd-H(D){sub 2}.

International Nuclear Information System (INIS)

The formation kinetics of Pd_2Si for fully silicided (FUSI) gate formation and the work function tuning of a Pd_2Si FUSI gate by impurity predoping were investigated. It has been found that the morphology and phase of a formed FUSI layer depend not only on the silicidation annealing temperature but also on the heating ramp-up rate and the presence of impurities. Fast ramp-up annealing was necessary to avoid defect formation, such as voids in the silicide film at the oxide interface, and to obtain a homogeneous silicide film containing only Pd_2Si phase. The most severe effect on the silicidation reaction, that is the increase in defect formation, was brought about by As predoping. The work function of the Pd_2Si FUSI gate was modulated by impurity pileup at the Pd_2Si/SiO_2 interface, as in the case of the NiSi FUSI gate. However, the work function shifted in the opposite direction ...

Science.gov (United States)

Charge flow and valence/d-band behavior in ion-beam-mixed (IBM) Pd1-xAgx (x = 0.5-0.9) alloys have been studied by X-ray photoemission measurement of the valence bands and of core-level binding energy shifts and X-ray absorption near-edge structure. We correlated the observed Ag 3d5/2 core-level shifts in these IBM alloys, relative to the elemental Ag, with the White Line area changes at the Pd and Ag L3-edge to investigate the charge redistribution at the Ag site. The results indicate that there is a decrease in sp-like conduction electron and a negligible change in the number of d-electrons at the Ag site upon alloying. These results are in line with our previous results in which Pd gains d-charges and loses sp-type charges. This electron redistribution due to hybridization in the alloy leads small net charge transfer from the Ag site to the Pd site in accordance with electronegativity predictions. ...

Science.gov (United States)

Pd-Ag bimetallic catalysts, supported on gamma-Al2O3, have been evaluated as exhaust catalysts for methanol-fueled vehicles. Laboratory studies have shown that a 0.01% Pd-5% Ag catalyst has greater CO and CH3OH oxidation activity than either 0.01% Pd or 5% Ag catalysts alone. Moreover, Pd and Ag interact synergistically in the bimetallic catalyst to produce greater CO and CH3OH oxidation rates and lower yields of methanol partial oxidation products than expected from a mixture of the single-component catalysts. The Pd-Ag synergism results from Pd promoting the rate of O2 adsorption and reaction with CO and CH3OH on Ag. Rate enhancement by the bimetallic catalyst is greatest at short reactor residence times where the oxygen adsorption rate limits the overall reaction rate.

British Library Electronic Table of Contents (United Kingdom)

ZusammenfassungUbelkeit und Erbrechen stellen zwei Symptome dar, die grundlich untersucht worden sind und bei Krebspatienten haufig auftreten. Die meisten Studien haben sich bislang mit Haufigkeit und Management dieser beiden Symptome befasst. Das Ziel dieser Studie bestand darin, ein besseres Verstandnis dafur zu entwickeln, wie Krebspatienten ihre Symptome erleben-insbesondere Ubelkeit und Erbrechen nach Chemotherapie-und welche Auswirkungen diese Symptome auf den Tagesablauf der Patienten haben. Neun Frauen mit unterschiedlichen Krebsleiden und Chemotherapie Regimes wurden zwecks Chemotherapie stationar aufgenommen und nahmen an der Studie teil. Es wurden halbstrukturierte Interviews einschliesslich einer Inhaltsanalyse in Anlehnung an Kvale durchgefuhrt (Klarung und Entwicklung neuer B...

British Library Electronic Table of Contents (United Kingdom)

In this article I explore the political event of the Tanzanian government's interdiction of a prominent educational civil society organization in order to theorize the emerging policy heterarchy in Tanzania. In the context of the ensuing public debate about the interdiction, I ask two questions: (1) what tensions are emerging from the democratization reforms embedded in national iterations of international EFA policies and (2) to what end are such reforms taking place? I address these questions with ethnographic, documentary and interview data collected as part of a broader study of participation in development between 2004 and 2007 in Dar es Salaam and the Singida region of central Tanzania. My analysis draws on critical, anthropological and postcolonial theories to explore the tensions o...

International Nuclear Information System (INIS)

The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol-1?m2 for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in ...

Energy Technology Data Exchange (ETDEWEB)

To determine clinical predictors and accuracy of {sup 123}I-FP-CIT SPECT imaging in the differentiation of drug-induced parkinsonism (DIP) and Parkinson's disease (PD). Several clinical features and {sup 123}I-FP-CIT SPECT images in 32 patients with DIP, 25 patients with PD unmasked by antidopaminergic drugs (PDu) and 22 patients with PD without a previous history of antidopaminergic treatment (PDc) were retrospectively evaluated. DIP and PD shared all clinical features except symmetry of parkinsonian signs which was more frequently observed in patients with DIP (46.9%) than in patients with PDu (16.0%, p<0.05) or PDc (4.5%, p<0.01). Qualitatively {sup 123}I-FP-CIT SPECT images were normal in 29 patients with DIP (90.6%) and abnormal in all patients with PD, and this imaging technique showed high levels of accuracy. DIP and PD are ...

International Nuclear Information System (INIS)

Single-crystalline CeRh_2Si_2 and CePd_2Si_2 were grown by the Czochralsky pulling method and the temperature dependence of magnetic susceptibility was investigated. The crystalline electric field (CEF) states in each compound were determined by considering the tetragonal CEF Hamiltonian with mean-field approximation. Interactions between Ce"3"+ ion and the surrounding ligands in CeRh_2Si_2 turned out to be strong and highly anisotropic in comparison to CePd_2Si_2. (orig.)

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The transformation of Pd/Si to Pd{sub 2}Si/Si is investigated using depth-resolved positron annihilation, x-ray diffraction and Auger electron spectroscopy studies. The observed defect-sensitive positron S-parameter value of 1.022-1.054 indicates the existence of divacancies across the silicide/silicon interface and Si substrate region. Our experimental observation of vacancy defects is consistent with the model proposed for excess vacancy generation across the interface consequent to Si diffusion. (letter to the editor)

Science.gov (United States)

The results of the second phase of the program of developing low cost contacts to silicon solar cells using copper are presented. Phase 1 yielded the development of a plated Pd-Cr-Cu contact system. This process produced cells with shunting problems when they were heated to 400 C for 5 minutes. Means of stopping the identified copper diffusion which caused the shunting were investigated. A contact heat treatment study was conducted with Pd-Ag, Ci-Ag, Pd-Cu, Cu-Cr, and Ci-Ni-Cu. Nickel is shown to be an effective diffusion barrier to copper.

Energy Technology Data Exchange (ETDEWEB)

The variation of surface composition and sintering of the binary Pd{sub 7}Ag{sub 3} nanoparticles prepared by chemical reduction were studied. The composition of the as-prepared Pd{sub 7}Ag{sub 3} nanoparticles across the diameter is inhomogeneous due to different reduction potentials of Pd and Ag. Upon heating, Ag will migrate to the surface because of its lower surface energy. Surface modification results in variation of surface composition during the sintering process. Stearic acid acts as a grain growth inhibitor. The migration of Ag to the surface is suppressed and the sintering is retarded. Modification by polyethylene glycol leads to more migration of Ag atoms from the core to the surface. This makes the nanoparticles easier to sinter.

Energy Technology Data Exchange (ETDEWEB)

The ternary zirconium palladium silicide ZrPd{sub 3}Si{sub 3} has been synthesized by arc-melting of the elemental components. It adopts a new structure type and crystallizes in the orthorhombic space group Cmcm with a = 3.8127(4){angstrom}, b = 15.551(1){angstrom}, c = 7.0390(5){angstrom}, and Z = 4 (Pearson symbol oC28). The structure can be regarded as being built up of Re{sub 3}B-type slabs of composition Pd{sub 3}Si alternating with {alpha}-FeSi{sub 2} slabs of composition ZrSi{sub 2}. Notable features include the presence of Si{sub 2} pairs, square pyramidal and tetrahedral coordination of Pd centers by Si atoms, an unusual distorted cubic coordination of the Zr atoms by the Si{sub 2} pairs, and an extensive network of Zr-Zr, Zr-Pd, and Pd-Pd metal-metal bonds. ZrPd{sub 3}Si{sub 3} is weakly metallic with a room-temperature resistivity of 1.7 x 10{sup ...

International Nuclear Information System (INIS)

Portuguese 1986. p. 186. Brazil Achete, CA Rio de Janeiro Univ. (Brazil).

Science.gov (United States)

The formation of palladium silicides near the interface may decrease hydrogen solubility at the effective metal/semiconductor ...

Energy Technology Data Exchange (ETDEWEB)

The growth of thin Pd[sub 2]Si films on Si(111) surfaces is studied using [ital in] [ital situ] transmission electron microscope under ultrahigh vacuum conditions. No immediate reaction of deposited Pd with Si is observed at room temperature. At [similar to]200 [degree]C, uniform Pd[sub 2]Si films can be formed. The thin Pd[sub 2]Si films are found to grow into strained islands at elevated temperatures. Interfacial misfit dislocations associated with interfacial steps propagate across the strained islands, causing the islands to grow layer-by-layer at the interface. The strain fields associated with the misfit dislocations are believed to be responsible for this behavior.

International Nuclear Information System (INIS)

Neutron diffraction and magnetometric measurements on polycrystalline samples of DyPd_2Si_2 and ErPd_2Si_2 were carried out in the temperature range from 2 to 293 K. Both compounds show tetragonal ThCr_2Si_2 type crystal structure and order at 12 K in a sine modulated magnetic structure with propagation vectors k=[0.609,0,0.155] and [0.575, 0, 0.083] respectively. The oscillatory character of magnetic order found in RPd_2Si_2 (R=Tb-Er) compounds suggests exchange interaction described by the RKKY model to be dominant, but the non-monotonic dependence of respective Neel temperatures on the number of f-electrons indicates the influence of a crystalline electric field (CEF) on the magnetic behaviour in this series. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The effect of varying pD(11-13,7) on the reaction of hydrogen with (Co/sup 11/(CN)/sub 5/)/sup 3/- in deuterium oxide has been studied by using infrared spectroscopy to determine the ratio of (Co/sup 111/(CN)/sub 5/X)/sup 3/- (X=H,D) in the solids precipitated from the steady state under hydrogen. The results show that the uptake of hydrogen does not liberate a free proton and that the rate of (Co/sup 111/(CN)/sub 5/H)/sup 3/- -D/sub 2/,0 exchange increases with pD but becomes pD independent at pD 7 greater than 13,5.

Energy Technology Data Exchange (ETDEWEB)

The evolution of strain in the Pd-Si system during the growth of Pd{sub 2}Si thin films on Si (100) substrate has been followed in situ using a double optical beam technique. As was observed for the Pt-Si system, the reaction to form Pd{sub 2}Si yields a compressive intrinsic surface film stress as well as for the silicon-rich suicides as proposed by Angilello et al. [Thin Film Interfaces and Interactions, edited by J. Baglin and J. Poate (The Electrochemical Society, Pennington, NJ, 1980)]. A transmission electron microscopy analysis has revealed grain growth during the formation of Pd{sub 2}Si which cannot account for the compressive film stresses. The formation of silicide at the interfaces rather than the overall change in volume agrees with the sign of the stresses formed. 29 refs., 4 figs., 3 tabs.

Energy Technology Data Exchange (ETDEWEB)

High-field magnetization properties of single crystalline CeRh{sub 2}Si{sub 2} and CePd{sub 2}Si{sub 2} were investigated. Two-step metamagnetic transition (H{sub c1}=25.4 T and H{sub c2}=26.0 T) was observed in the case of CeRh{sub 2}Si{sub 2}, whereas no anomaly was found in the magnetization process of CePd{sub 2}Si{sub 2} up to 28 T. The mean field analysis has shown that CeRh{sub 2}Si{sub 2} is quite anisotropic compared to CePd{sub 2}Si{sub 2}, which results in the sharp contrast between the magnetization processes of the two compounds.

Science.gov (United States)

... 2.2.1 Polymerization of DVB Under Pressure DVB was polymerized at 300*C in thin-walled Pd-Ag capsules at pressures up to 60,000 psi. ...

International Nuclear Information System (INIS)

... dipole moments magnetic fields monocrystals neutron diffraction order-disorder

Science.gov (United States)

Jul 26, 2011 ... The Gateway to Astronaut Photography of Earth hosts the best and most complete online collection of astronaut photographs of the Earth.

Energy Technology Data Exchange (ETDEWEB)

Pd/sub 2/Si formation at the Pd-Si interface induced by irradiation with ions having a wide range of nuclear energy of deposition density has been investigated. It is found that the thickness of the silicide layer formed by irradiation is proportional to the ion fluence for irradiation with ions having low energy-deposition densities, while it is proportional to the square root of the fluence for irradiation with ions having energy-deposition densities. The results indicate that Pd/sub 2/Si formation is reaction limited when the energy-deposition density at the interface is low and is diffusion limited when it is high. The results are compared with the phenomenological theory developed by Horino et al. and it is shown that such a dependence of the limiting processes on the energy depositon density is induced when the diffusion is thermally activated while the reaction at the interface is radiation-enhanced.

International Nuclear Information System (INIS)

We report studies of bimetallic nanoparticles with 15%-16% atomic crystal parameters size mismatch. The degree of alloying was probed in a 2-nm Pt core (smallest attainable core size) of Pt-Ag nanoparticles (completely immiscible in bulk) and 20-nm-diameter Pd-Ag nanowires (completely miscible in bulk). Particles were synthesized radiolytically, and depending on the initial parameters, they assume spherical or cylindrical (nanowire) morphologies. In all cases, the metals are seen to follow their bulk alloying characteristics. Pt and Ag segregate in both spherical and wire forms, which indicates that strain due to crystallographic mismatch overcomes the excess surface free energy in the small particles. The Pd-Ag nanowires alloy similar to previously reported spherical Pd-Ag particles of similar diameter and composition.

International Nuclear Information System (INIS)

Different semi precious alloys (Pd-Ag, Pd-Au) have been studied after thermal oxidation treatments to analyze the mechanical improvement of the interface between the metal and the ceramic. Using the four point bending test, the authors have analyzed the different steps corresponding to the mechanical evolution of the bi-material : cracking energy on the surface, relaxation energy after first cracking, propagation energy of cracks at the interface zone. It has been shown that some alloys only have a high resistance to the interface cracking and the role played by the interface reactions to improve this property. (orig.).

Science.gov (United States)

The formation and properties of Pd{sub 2}Si formed by focused ion beam implantation of Pd ions into Si is presented in this thesis. An extensive microstructural study using transmission electron microscopy was undertaken and the as-implanted as well as annealed microstructure is shown. Results of other analysis techniques such as Rutherford back scattering and secondary ion mass spectrometry etc. are also presented. Kinetic information on the growth of Pd{sub 2}Si obtained by both microstructural and resistance measurements indicates that the activation energy for growth of the silicide is around 0.36 to 0.39 eV. This can be compared with the normally reported value of 1.5 eV for Pd{sub 2}Si formed by annealing thin film Pd on Si. The growth of the silicide was found to follow t{sup 1/2} kinetics. Microstructural observation of the as-implanted samples showed extensive in-situ ...

Science.gov (United States)

The applicability of Pd/sub x/Ta/sub 1-x/ as a diffusion barrier on Si has been investigated. For this purpose Pd/sub x/Ta/sub 1-x/ films of 200 nm thickness (x ranges from 0 to 1) were deposited on Si(100), and the reaction between over-layer and substrate was studied as a function of temperature. Interaction was found to occur at temperatures increasing with the Ta content. The as-deposited Pd/sub x/Ta/sub 1-x/ films with 0.2 less than or equal to x less than or equal to 0.6 were found to be amorphous. The amorphous phase had a higher reaction temperature than the crystalline one, causing a discontinuous step in the reaction temperature. RBS spectra revealed that for the Pd-rich compositions first a stoichiometric Pd2Si layer formed underneath a pure Ta layer. At higher temperatures TaSi2 formed at the surface. For Ta-rich compositions Pd2Si formed first as ...

CERN Document Server

Three-flavor lattice QCD simulations and two-loop perturbation theory are used to make the most precise determination to date of the strange-, up-, and down-quark masses, $m_s$, $m_u$, and $m_d$, respectively. Perturbative matching is required in order to connect the lattice-regularized bare- quark masses to the masses as defined in the \\msbar scheme, and this is done here for the first time at next-to-next-to leading (or two-loop) order. The bare-quark masses required as input come from simulations by the MILC collaboration of a highly-efficient formalism (using so-called ``staggered'' quarks), with three flavors of light quarks in the Dirac sea; these simulations were previously analyzed in a joint study by the HPQCD and MILC collaborations, using degenerate $u$ and $d$ quarks, with masses as low as $m_s/8$, and two values of the lattice spacing, with chiral extrapolation/interpolation to the physical masses. With the new perturbation theory ...

Energy Technology Data Exchange (ETDEWEB)

The atrial myocardium has been barely visible with thallium-201 myocardial scintigraphy. This is probably related to the difference in size, distance from anterior chest wall, and small coronary blood flow of the atrium, compared with the ventricle. We have encountered eight cases of visualization of the right atrial appendix (RAA). The RAA was identified from multiple projections in all cases and sometimes confirmed by radionuclide angiocardiography. Evidence derived from ECG, chest radiographs, and cardiac catheterization, indicated that the most important factor in the visualization might be the displacement of the RAA to a more anterior position.

Energy Technology Data Exchange (ETDEWEB)

A solar cell structure is produced by a method comprising baking the solar cell, containing a gridded top layer of cuprous sulfide formed on a base of cadmium sulfide, for 20 minutes to 10 hours, to produce a copper doped cds electrically insulating region in the cadmium sulfide base near the interface of the cuprous sulfide and the cadmium sulfide; removing the cuprous sulfide, and the copper doped cds insulating region not covered by the grid, to provide a bare cadmium sulfide areas; and then forming a cuprous sulfide layer on the exposed areas not covered by the grid.

Energy Technology Data Exchange (ETDEWEB)

In this first quarterly technical report for DOE Contract No. DE-AC22-87PC79654, a description of the background, technology, and application is provided. The design and fabrication of advanced combustion chambers were completed during this period. Initial testing on both the bare metal and refractory lined advanced chambers were initiated. The units were tested initially with gas but primarily with coal. A Pittsburgh No. 8 pulverized coal was used for these test activities. Both advanced chambers pulsed well.

Energy Technology Data Exchange (ETDEWEB)

The Si L/sub 2/ /sub 3/VV Auger Lineshape for Pd/sub 4/Si was measured and found to be in good agreement with the self-fold of the Si partial density of states model calculated by Riley et al. Oxygen chemisorption altered both the Auger lineshape and the HeI photoemission spectrum, especially near the Fermi energy.

Energy Technology Data Exchange (ETDEWEB)

The possibilities and problems of PCA in phase separation are shown on Ni, Pd, and Pt silicides. The PCA depth profiles are less influenced by sputter and matrix effects than usual Auger depth profiles. The position of the silicide-Si interface is well defined by the component distribution crossover in PCA profiles. An interface component between Pd and Pt silicides and Si substrate is determined by PCA.

Science.gov (United States)

The achievement of inner-shell photoionization of Zn-like Pd by means of two exploding foils is described. This resulted in the soft X-ray transition 3d94s2-3d104p at 46 A. It is shown that the photoionization of inner shell electrons in highly stripped ions can lead to X-ray transitions which may be candidates for X-ray lasers under 50 A.

International Nuclear Information System (INIS)

The magnetic excitations of the Kondo compound CePd_2Si_2 below its Neel temperature (T_N = 10 K) have been studied by inelastic neutron scattering. At T = 1.6 K the data are best represented by two dispersive inelastic modes. Their linewidth (#propor to# 0.5 meV) indicates substantial broadening, which is ascribed to Kondo-type local fluctuations. (orig.).

Energy Technology Data Exchange (ETDEWEB)

We report on solid solution CePd[sub 2-x]Mn[sub x]Si[sub 2] which shows an interesting transition of the Ce-ion from magnetism in a Kondo regime to an intermediate valence state coupled with a strongly magnetic 3d sublattice. ((orig.))

Energy Technology Data Exchange (ETDEWEB)

Experimental data in the Kondo lattice YbPd{sub 2}Si{sub 2} is compared with the results of a hybridization model, based ont he 'large degeneracy expansion' approximation, which takes into account the crystal field level splittings of the Yb ion. We show that satisfactory agreement is obtained with a unique set of crystal field and hybridization parameters. (orig.).

International Nuclear Information System (INIS)

We report resistivity and thermopower measurements of the heavy fermion compound CePd_2Si_2 at pressures up to 56 kbar. At pressures from 21 to 34.5 kbar, we measured the resistivity down to 30 mK, for all other pressure steps the temperature range was 1.2-300 K. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Density changes in amorphous Pd{sub 80}Si{sub 20} during ion irradiation below 100K were detected by in situ HVEM measurements of the changes in specimen length as a function of ion fluence. A decrease in mass density as a function of the ion fluence was observed. The saturation value of the change in mass density was determined to be approximately -1.2%.

International Nuclear Information System (INIS)

Plasma-deposited thin films prepared at room temperature, ranging from 46 to 250 A of PdAu on #approx#45-50 A Si-oxide and Si-oxynitride films grown on Si wafers were studied. Grazing incidence X-ray diffraction, X-ray reflectivity, and XPS depth profile techniques were used to characterize the thin films. A reactive interface involving Pd- and Au-silicides is formed, linking the thin film to the Si-oxide and Si-oxynitride films: a small fraction of Pd and Au atoms from PdAu migrate into the Si substrate, first penetrating the oxide layer, and the small fraction of Si atoms from the oxide layer migrate into the PdAu film and form a silicide interlayer consisting of a reactive interface made up of mixtures of Au- and Pd-silicides interspersed within the matrix of PdAu and substrate. The concentration profiles of these silicides have a maximum ...

Science.gov (United States)

This paper describes the anelastic strain recovery and the strain hardening of amorphous metals and presents the experimental result that creep deformation is represented by a viscoelastic model consisting of rheological elements. Materials studied were 80Pd--20Si, 80Fe--13P--7C, and 60 Cu--40 Zr. (DLC)

Energy Technology Data Exchange (ETDEWEB)

Alkaline fuel cells (AFCs) provide a less corrosive environment and can provide higher electrode reaction kinetics than proton exchange membrane fuel cells (PEMFCs). The alkaline media also allows for the replacement of platinum (Pt) based electrocatalysts with non-Pt electrocatalysts. Studies have shown that palladium (Pd) and silver (Ag) form a homogenous solid solution with a face-centred cubic structure within a large range of temperatures. This study described the results of an oxygen reduction reaction (ORR) on lead-silver (Pd-Ag) alloy electrodes in alkaline media. The reaction was compared with Pd and Ag electrodes. The alloys were synthesized as thin films using a sequential electroless deposition of Pd and Ag on stainless steel discs followed by an annealing procedure in an Ar stream. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used ...

International Nuclear Information System (INIS)

The changes in the electrical and structural properties of metal-silicide films caused byion implantation and subsequent thermal annealing have been investigated. Epitaxial silicide films such as those of CoSi"2, NiSi"2 and Pd"2Si grown on Si(111) substrates were implanted with Ar ions and annealed in a vacuum furnace at temperatures ranging from 200 to 800_0C. Rutherford backscattering and channeling techniques and the four-point probe method were used to measure the crystalline quality and the sheet resistance of the films, respectively. It was found that the sheet resistances of CoSi"2, NiSi"2 and Pd"2Si films were increased by factors of 70, 6, and 3, respectively, by implantation to a dose of 1 x 10_1_6 Ar-ions/cm_2, but that they were almost restored by subsequent annealing to the values before implantation. A phase transformation from Pd"2Si to PdSi was also observed in the high-temperature ...

Science.gov (United States)

A simple one-step method to fabricate hierarchically porous TiO2/Pd composite hollow spheres without any template was developed by using solvothermal treatment. Pd nanoparticles (2-5 nm) were well dispersed in the mesopores of the TiO2 hollow spheres via in-situ reduction. In our experiment, polyvinylpyrrolidone played an important role in the synthetic process as the reducing agent and the connective material between TiO2 and Pd nanoparticles. HF species generated from solvothermal reaction leaded to the formation of TiO2 hollow spheres and Ostwald ripening was another main factor that affected the size and structure of the hollow spheres. The as-prepared TiO2/Pd composite hollow spheres exhibited high electrocatalytic activity towards the reduction of H2O2. The sensitivity was about 226.72 ?A mM-1 cm-2 with a detection limit of 3.81 ?M at a signal-to-noise ratio of 3. These results made the ...

Energy Technology Data Exchange (ETDEWEB)

The oxide colloidal route, developed in the laboratory for mono-metallic catalysts, consists in preparing a metallic oxide hydro-sol which leads to the supported catalyst after deposition onto a support and an activation stage. In this work, this method has been adapted to the preparation of alumina supported bimetallic Pd-Sn catalysts to determine its interest for the control of the properties of the bimetallic phase (size, composition and structure). In the preliminary study concerning tin oxide sols, SnO{sub 2} (size=2,3 nm) and Sn{sub 6}O{sub 4}(OH){sub 4} (size = 25 nm) nano-particles were synthesized by neutralization respectively for tin(IV) and tin(H). The control through the pH of the aggregation of the PdO and SnO{sub 2} particles revealed that increasing oxide solubility promotes integral re-dispersion of the oxide particles. To synthesize oxide bimetallic sols, three strategies were defined. Copolymerization (formation of a mixed ...

Energy Technology Data Exchange (ETDEWEB)

TENSOMAX enables on-line monitoring of the thermal stress of the shaft to be performed in steam turbines, for which the TURBOMAX probe cannot be installed near the critical area of the shaft. TENSOMAX provides an alternative to the TURBOMAX with a slightly reduced accuracy of the simulation of the temperature distribution in the shaft. The high value placed on the operational performance of TENSOMAX remains, viz. that even with older turbines, and particularly in the case of turbines rehabilitated with a new shaft, careful and transparent operation is assured. (orig.) [German] Die Einrichtung TENSOMAX ermoeglicht eine Ueberwachung der thermischen Beanspruchung der Welle bei Dampfturbinen, bei denen die TURBOMAX-Sonde in der Turbine nahe der kritischen Stelle der Welle nicht einsetzbar ist. Daher stellt der TENSOMAX unter Beruecksichtigung minimaler Ungenauigkeit aufgrund der Nachbildung der Waermeuebergangszahl eine vorteilhafte Alternative zum TURBOMAX dar. Der ...

Energy Technology Data Exchange (ETDEWEB)

Meltdown and gasification of waste in an oxygen atmosphere ('2sv' process) is an economically efficient alternative to energetic and thermal utilisation of biomass. Organic pollutants are split at temperatures up to 2000 C in a reducing atmosphere. The process uses elements of the oxygen cupola furnace for melting and gasification of many different waste fractions, e.g. polluted waste wood, household refuse and bulk waste, old tyres, light shredder fractions, sewage sludge, etc. [German] Die Sauerstoff-Schmelz-Vergasung ('2sv') stellt eine wirtschaftliche Alternative zur energetischen Nutzung von Biomassen wie auch zur thermischen Abfallverwertung dar. Organische Schadstoffe werden bei diesem neuen Verfahren bei Temperaturen bis zu 2000 C unter reduzierenden Bedingungen aufgespalten. Das Verfahren nutzt Elemente des Sauerstoff-Kupolofens fuer die Schmelzvergasung und eignet sich fuer zahlreiche Abfallarten wie z.B. belastetes ...

Energy Technology Data Exchange (ETDEWEB)

The second volume contains a comprehensive presentation of inflammatory bone diseases, including seldom primary chronic osteomyelitis and morbus Paget. Substantial chapters on bone tumors and tumor-like lesions of bone joints are covering the state-of-the-art of diagnostic techniques of these seldom but important diseases. Besides the importance of projection radiography the contribution of MRI within differential diagnosis und staging of these diseases is emphasized. [German] Der zweite Band des Muskuloskelettalen Systems befasst sich mit der umfassenden Darstellung zur Diagnostik entzuendlicher Knochenerkrankungen und beinhaltet neben den klassischen infektioesen auch die seltenen, primaer chronischen Osteomyelitiden und den Morbus Paget. Umfangreiche Kapitel ueber die Knochentumoren und tumoraehnlichen Laesionen der Gelenke stellen in modernster Weise den aktuellen Stand des Wissens und der Diagnostik dieser seltenen, aber aus differenzialdiagnostischer Sicht sehr wichtigen ...

Energy Technology Data Exchange (ETDEWEB)

Endoluminal vascular prostheses that can be implanted by percutaneous routes represent the most recent development in vascular interventional radiology. Various commercially available types of prosthesis are presented and the construction principles and applications are described. At present secure indications for the implantation of endoluminal prostheses are limited to the elimination of aneurysms and arteriovenous fistulae of the large vessels near the trunk in sections that do not cross a joint. The wide use in peripheral occlusive diseases cannot yet be recommended because confirmed data are not available. (orig.) [German] Endoluminale Gefaessprothesen, die perkutan implantierbar sind, stellen die juengste Entwicklung in der vaskulaeren interventionellen Radiologie dar. Verschiedene kommerziell erhaeltliche Prothesentypen werden vorgestellt, ihr Konstruktionsprinzip und ihre Applikation erlaeutert. Die gesicherten Indikationen zur endoluminalen ...

International Nuclear Information System (INIS)

Reactively sputtered tantalum nitride (Ta_2N) has been investigated as a diffusion barrier between Pd_2Si and aluminum and CoSi_2 and Al. Ta_2N is found to be an excellent matallurgical diffusion barrier for the two systems up to 555 "0C, with no intermixing observed in Rutherford backscattering and Auger electron spectroscopic studies. Schottky barrier devices n-Si/Pd_2Si/Ta_2N/Al were excellent and showed no deterioration after annealing at 500 "0C. However, similar devices with CoSi_2 contacts and Ta_2N barrier showed a creation of high contact resistance between the silicide and the as-deposited nitride.

British Library Electronic Table of Contents (United Kingdom)

Bilayers of pure palladium and gold films were evaporated alternatively on (100) and (111) monocrystalline silicon substrates. After annealing, in a vacuum furnace from 100 to 650degreeC during 30min, the growth sequence of the Pd2Si and PdSi phases that evolved as the result of the diffusion reaction was examined by means of Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD), whereas the surface morphology was investigated by scanning electron microscopy (SEM) technique. The effect of the intermediate gold layer is investigated in order to test its effectiveness as barrier for Cu and Si atoms interdiffusion and its influence on the morphology of the formed palladium silicides. The effect of substrate orientation on the palladium silicides growth and formation was also e...

International Nuclear Information System (INIS)

The redistribution of implanted As and Sb following metal-silicide formation of Pt, Pd, and Ni has been studied. The phases of the silicides used were PtSi, Pd_2Si, and NiSi. Investigations with Rutherford backscattering analysis showed that after the formation of the silicides, the Sb was always found in the silicide layer near the surface of the samples, whereas PtSi and Pd_2Si caused a partial rejection of As for implanted doses of 2 x 10"1"5 cm"-"2 and higher. No rejection of As was found after the formation of NiSi. The results are discussed in terms of solid solubilities and impurity-metal compound formation. The data presented has implications in the fabrication of Ohmic contacts and the adjustments of the heights of Schottky barriers on silicon.

International Nuclear Information System (INIS)

Magnetization, neutron diffraction and "1"6"6Er Moessbauer measurements on ErPd_2Si_2 are reported. Below 4.8 K ErPd_2Si_2 orders AF with complex modulated magnetic structures, where the Er moments are aligned along the c-axis. At 1.5 K a squared structure with #mu#_E_r #approx# 7.8(1)#mu#_B is found while a saturation Er moment of 8.2(2)#mu#_B is inferred from the hyperfine field data. The temperature dependence of the Moessbauer spectra in the paramagnetic region is explained in the framework of a relaxation model implying excited crystal field levels. Its analysis is used to estimate the B"m_n CEF parameters. (orig.).

Energy Technology Data Exchange (ETDEWEB)

In the present study, element interdiffusions at the cofired interface of 9/1 Ag/Pd electrode and lead magnesium niobate (PMN)-based ferroelectrics were investigated using Auger Electron Spectroscopy (AES). Intense interdiffusions at the interface were observed while Ag and Pd could penetrate into the ceramics for about 1 {mu}m. Ag-doping experiments were carried out to further study the effects of Ag diffusion on electrical properties of the ceramics. The results showed that Ag could be incorporated into solid solution of the ceramics as Ag{sup +}. As a whole, the Curie temperature (Tc) and dielectric constant of the ceramics decreased with Ag addition. However, Ag addition had no obvious effect on the insulation resistivity. The results inferred that Ag{sup +} could substitute for Pb{sup 2+} at A site of ABO{sub 3} lattice, thereby oxygen vacancies were generated.

British Library Electronic Table of Contents (United Kingdom)

Palladium deposition on Pt(110) electrodes was studied. Differently from Pt(111) and Pt(100), first and further layers cannot be distinguished in this case only through the voltammetric behavior of hydrogen and anion adsorption. The potential of zero total charge (pztc) was determined as a function of the amount of deposited Pd using CO charge displacement experiments and voltammetric curves. The variation of the voltammetric charge due to hydrogen and anion adsorption has been followed during Pd deposition. The voltammetric charge between 0.06 and 0.4V first decreases to a minimum, then increases and finally becomes stable, suggesting that the surface is finally covered with a Pd multilayer. The pztc and CO oxidation charge show similar behavior. CO oxidation, NO reduction and Cu UPD were...

Energy Technology Data Exchange (ETDEWEB)

The growth of the Pd{sub 2}Si thin fllms on Si(111) substrates has been monitored by an {ital in} {ital situ} x-ray diffraction technique in vacuum and in helium atmosphere from 160 to 250 {degree}C. A familiar parabolic growth rate was found, confirming the diffusion-controlled film growth process. The activation energies were found to be 1.34 and 1.37 eV for the measurements performed in vacuum and helium environment, respectively. Stress relaxation in the growing Pd{sub 2}Si fllm was observed when the reaction temperature exceeds 200 {degree}C. The relaxed films showed a higher degree of texture as evidenced by the rocking curve measurements.

Science.gov (United States)

Phase relations in the ternary system Ce-Pd-Si have been established for the isothermal section at 800 deg. C based on X-ray powder diffraction and EMPA techniques on about 130 alloys, which were prepared by arc-melting under argon or powder reaction sintering. Eighteen ternary compounds have been observed to participate in the phase equilibria at 800 deg. C. Atom order was determined by direct methods from X-ray single-crystal counter data for the crystal structures of tau{sub 8}-Ce{sub 3}Pd{sub 4}Si{sub 4} (U{sub 3}Ni{sub 4}Si{sub 4}-type, Immm; a=0.41618(1), b=0.42640(1), c=2.45744(7) nm), tau{sub 16}-Ce{sub 2}Pd{sub 14}Si (own structure type, P4/nmm; a=0.88832(2), c=0.69600(2) nm) and also for tau{sub 18}-CePd{sub 1-x}Si{sub x} (x=0.07; FeB-type, Pnma; a=0.74422(5), b=0.45548(3), c=0.58569(4) nm). Rietveld refinements established the atom arrangement in the structures of tau{sub 5}-Ce{sub ...

Energy Technology Data Exchange (ETDEWEB)

Advances in the theory and practice of stress corrosion cracking (SCC) are reviewed for the period 1965-1990. The proceedings of two landmark conferences are used as a basis for discussion: Ohio State University (1967) and Kohler, WI (1988). The discussion is developed around the following topics: metal-environment combinations, testing, fractography, metallurgical aspects, electrochemical aspects and crack chemistry, mechanisms, and prediction and mitigation. It is concluded that the main developments since 1967 are the recognition of the lack of specificity of SCC environments, the use of slow strain rate and fracture mechanics testing, quantitative SEM fractography, studies of grain boundary structure and compositions, transient electrochemistry of bare metal surfaces, measurement and modelling of crack chemistry, elaboration of several SCC models, including slip-dissolution and film induced cleavage, and mitigation by alloy development or anodic protection. ...

Energy Technology Data Exchange (ETDEWEB)

The reduction of oxygen was studied in 0.1 M KCl at 70 deg. C using the rotating disk electrode (RDE) technique on platinum and electrodeposited ZnO thin film electrodes deposited on platinum substrates. In the absence of Zn{sup 2+} ions in solution, a Tafel slope of 139 mV dec{sup -1} was obtained, a value close to that measured on bare platinum electrode (133 mV dec{sup -1}) and ascribed to the limitation of the reaction rate by the first electron transfer. The main difference between the noble metal and the oxide electrode was a shift of the curves towards more negative potentials. In the presence of Zn{sup 2+} ions, the current density decreased significantly and the Tafel slope was measured at 282 mV dec{sup -1} showing that the electrode was partially blocked by zinc oxide formation reaction intermediates.

CERN Document Server

Modern scientific data mainly consist of huge datasets gathered by a very large number of techniques and stored in very diversified and often incompatible data repositories. More in general, in the e-science environment, it is considered as a critical and urgent requirement to integrate services across distributed, heterogeneous, dynamic "virtual organizations" formed by different resources within a single enterprise. In the last decade, Astronomy has become an immensely data rich field due to the evolution of detectors (plates to digital to mosaics), telescopes and space instruments. The Virtual Observatory approach consists into the federation under common standards of all astronomical archives available worldwide, as well as data analysis, data mining and data exploration applications. The main drive behind such effort being that once the infrastructure will be completed, it will allow a new type of multi-wavelength, multi-epoch science which can only be barely ...

International Nuclear Information System (INIS)

Understanding the erosion and deposition rates in a small watershed is important for designing soil and water conservation measures. The objective of this study is to estimate the net soil loss and gain at points with various land use types and landform positions in a small watershed in the Sichuan Hilly Basin of China by the 137Cs tracing technique. Among various land use types, the order of erosion rate was bare rock > sloping cultivated land > forest land. The paddy field and Caotu (a kind of cultivated land located at the foot of hills) were depositional areas. The erosion rate under different landform was in this order: hillside > saddle > hilltop. The footslope and the valley were depositional areas. The 137Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small watershed.

Energy Technology Data Exchange (ETDEWEB)

Presently, most charge state distributions produced with highly charged ion sources are predicted with models that approximate the ionization process with the Lotz formula. The Lotz ionization cross sections decrease approximately geometrically with increasing charge state except for ions with very few vacancies, for ions with very few electrons, and for electron impact energies which barely exceed the ionization energy. The geometrical decrease causes these models to predict a maximum abundance for most of the charge states, which is only weakly dependent on the charge state. Experimental results, however, yield much higher abundances for ions with an empty M shell than ions with a partly filled M shell. This difference is explained with indirect ionization processes that are neglected by the Lotz approximation, and normally can be neglected for the ionization of the L shell, but can dominate the ionization of the M shell. (c) 2000 American Institute of Physics.

CERN Document Server

In this paper, we present a very important primitive called Information Checking Protocol (ICP) which plays an important role in constructing statistical Verifiable Secret Sharing (VSS) and Weak Secret Sharing (WSS) protocols. Informally, ICP is a tool for authenticating messages in the presence of computationally unbounded corrupted parties. Here we extend the basic bare-bone definition of ICP, introduced by Rabin et al. and then present an ICP that attains the best communication complexity and round complexity among all the existing ICPs in the literature. We also show that our ICP satisfies several interesting properties such as linearity property which is an important requirement in many applications of ICP. Though not presented in this paper, we can design communication and round efficient statistical (i.e involves negligible error probability in computation) VSS and Multiparty Computation (MPC) protocol using our new ICP.

Energy Technology Data Exchange (ETDEWEB)

Anodic protection makes it possible to keep materials which can be passivated in a 'passive' state or to bring them into this state, even in unfavourable conditions. With sulphuric acid concentrations of 93-99% this method permits the use of inexpensive, stainless austenitic steels, e.g. 1.4541 and 1.4591, at temperatures of up to 160/sup 0/C. The temperature range from 120/sup 0/C, in particular, is suitable for heat recovery. Anodic protection by the APR-system provides safe and low-cost protection for air coolers and bare tube coolers in sulphuric acid plants. The results of laboratory, pilot plant and commercial trials show that in this way a safe operation of sulphuric acid coolers is possible on a long-term basis.

Science.gov (United States)

Silicon carbide (SiC) based electronic devices are of great importance for applications under the condition of high temperature, high power and high radiation. Schottky diodes of Palladium/SiC are good candidates for hydrogen and hydrocarbon gas sensors at elevated temperature. The detection sensibility of the diodes has been found heavily temperature dependent. In this work, the electrical and chemical properties of Pd/SiC Schottky contacts were studied by XPS and AES at different annealing temperatures. Schottky diodes were made by depositing ultra-thin palladium films onto a silicon carbide substrate. No significant change in the Schottky barrier height of the Pd/SiC contact was found in the temperature range of 300-673K. Palladium diffusion into SiC and the formation of palladium silicides were observed at room temperature and became significant at 300^oC and higher temperature. The mechanism of diffusion and reaction at the ...

British Library Electronic Table of Contents (United Kingdom)

Phase relations in the ternary system Ce-Pd-Si have been established for the isothermal section at 800degreeC based on X-ray powder diffraction and EMPA techniques on about 130 alloys, which were prepared by arc-melting under argon or powder reaction sintering. Eighteen ternary compounds have been observed to participate in the phase equilibria at 800degreeC. Atom order was determined by direct methods from X-ray single-crystal counter data for the crystal structures of t8-Ce3Pd4Si4 (U3Ni4Si4-type, Immm; a=0.41618(1), b=0.42640(1), c=2.45744(7)nm), t16-Ce2Pd14Si (own structure type, P4/nmm; a=0.88832(2), c=0.69600(2)nm) and also for t18-CePd1-xSix (x=0.07; FeB-type, Pnma; a=0.74422(5), b=0.45548(3), c=0.58569(4)nm). Rietveld refinements established the atom arrangement in the structures of...

International Nuclear Information System (INIS)

The present work is to study effects of neutron irradiation on the structure of amorphous Pb_8_0 Si_2_0 and Pd_7_7_._5 Cu_6 Si_1_6_._5 alloys by using X-ray diffraction techniques. differential scanning calorimertry (DSC) and internal friction measurements. The irradiation will produce obvious changes in the pair correlation function g(r) and radial distribution function RDF (r). The increase of crystallization temperature (Tx) and enthalpy of two specimens were found by DSC measurements after irradiation. The results of internal friction measurement show that the internal friction of the irradiated Pd_8_0Si_2_0 alloy is higher than that of the unirradiated in the temperature range of T

International Nuclear Information System (INIS)

Marker experiments for studying the mass transport through a palladium silicide layer on a crystalline substrate during thermal oxidation at 700 to 850 deg C have been reported recently. In this work argon gas embedded in amorphous silicon during sputtering was implemented as the inert marker and the oxidation of PdSi was processed above 900 deg C. At this high-temperature oxidation silicon-rich silicide PdSisub(y), with y exceeding 5, may be obtained. This can be anticipated by considering the Pd-Si phase diagram which shows the liquid phase may appear at an annealing temperature above 892 deg C. As a result, a non-stoichiometric and non-uniform silicide layer may develop at the sample surface. Marker analysis showed that both palladium and silicon dissociated at the Pdsub(x)Si/ SiO_2 interface and moved to the substrate with the silicon being the dominant diffuser. The Rutherford backscattering spectra (RBS) showing the ...

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Available data are presented which support the supposition that metals and alloys with a negative low-temperature Hall coefficient are apparently not superconducting. (author).

UK PubMed Central (United Kingdom)

Objective:Parkinson disease (PD) may affect the autonomic nervous system and may cause constipation; however, few studies have explored constipation preceding the motor onset of...Full Text Available

UK PubMed Central (United Kingdom)

Objectives. To assess the feasibility of treating musculoskeletal pain in the lower back and/or lower extremities in persons with Parkinson's disease (PD) with cranial electrotherapy...Full Text Available

International Nuclear Information System (INIS)

The PERMCAT process chosen for the final clean-up stage of the Tokamak Exhaust Processing system of the ITER tritium plant combines in a single component a catalytic reactor and a permeator using Pd/Ag membranes. This study covers the mechanical behaviour of a Pd/Ag membrane under different operating conditions. The consequences of hydrogen uptake by the membrane during nominal operation but also during off-normal events are presented. Depending on the operating conditions, expansions around 2% and significant deformations are observed. Different mechanical designs of PERMCAT reactors are then discussed. The first generation comprises finger-type membranes and two new mechanical designs use either additional edge welded bellows or a special corrugated Pd/Ag membrane. These upgraded designs improve the robustness and simplify the geometry of the component. The experimental validation of these new units has been carried out ...

International Nuclear Information System (INIS)

We present first-time measurements of the Fermi surface and low-energy electronic structure of intermetallic compounds Gd_2PdSi_3 and Tb_2PdSi_3 by means of angle-resolved photoelectron spectroscopy (ARPES). We show that the Fermi surface in both compounds consists of an electron barrel at the #GAMMA# point surrounded by spindle-shaped electron pockets originating from the same band, with the band bottom of both features lying at 0.5 eV below the Fermi level. From the experimentally measured band structure, we estimate the momentum-dependent RKKY coupling strength and demonstrate that it is peaked at the 1/2#GAMMA# K wave vector. Comparison with neutron diffraction data from the same crystals shows perfect agreement of this vector with the propagation vector of the low-temperature in-plane magnetic order, thereby demonstrating the decisive role of the Fermi surface geometry in explaining the complex magnetically ordered ground state of ternary ...

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Two major modes of CO adsorption on SiO{sub 2}-supported Pd reflect different extents of back-donation, which is, at least in part, controlled by the local electron density at the adsorption site. The fraction of CO in the bridging mode (B) increases and that of the linear mode (L) decreases, with increasing size of the Pd particles, indicating high electron density at Pd atoms in terraces of close-packed crystal faces, in agreement with Smoluchowski's classical model. For samples reduced at 300{degree}C our data points and those of other authors are located on a common curve of B/L vs metal dispersion. Extensive reduction at 600{degree}C results in significantly lower B/L values, attributed to the incipient formation of a palladium silicide. Oxidation followed by reduction at 300{degree}C destroys the silicide, and the B/L value returns to the original curve.

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To attain reproducible and stable contacts to compound semiconductor devices, it is necessary to achieve thermodynamically stable phases after the reaction of metals with the compound semiconductor. In this study, the final phases produced by the reactions between GaAs and thin metal films of Co, Rh, Ir, Ni, Pd, and Pt have been investigated. They are identified as MGa for M = Co, Rh, Ni, Pd, and Pt, monoarsenides of Co and Ni, diarsenides of Rh, Ir, Pd, and Pt, and Ir/sub 3/Ga/sub 5/. These phases, if deposited directly onto GaAs, will produce thermally stable contacts. In addition to the identification of these stable phases, analyses of the products of thin-film M/GaAs reactions by transmission electron microscopy, x-ray diffraction, and Rutherford backscattering spectrometry reveal the distribution, grain size, and crystallographic texture of these end phases. Trends in these observations across the six metal/GaAs ...

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The annealing behavior of the radiation damage in epitaxial Pd_2Si and NiSi_2 films on Si, due to the implantation of 100 keV Ar ions, is investigated by using the channeling technique with "4He ions. (U.K.).

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Depth resolved positron annihilation studies on Pd/Si thin film system have been carried out to investigate silicide phase formation and vacancy defect production induced by thermal annealing. The evolution of defect sensitive S-parameter clearly indicates the presence of divacancy defects across the interface, due to enhanced Si diffusion beyond 870 K consequent to silicide formation. Corroborative glancing incidence X-ray diffraction (GIXRD), Auger electron spectroscopy (AES) and Rutherford backscattering spectrometry (RBS) have elucidated the aspects related to silicide phase formation and Si surface segregation.

International Nuclear Information System (INIS)

The magnetic structure of a tetragonal Ce(Ru_0_._9_6Pd_0_._0_4)_2Si_2 single crystal, determined by neutron diffraction measurements, is similar to that observed in Rh doped alloys. The magnetic moments are oriented and modulated along the c-axis. Here the wave vector is incommensurate: k=(0,0,0.38). At 1.5 K, the moment is estimated to about 0.3 #mu#_B. Magnetization, magnetoresistance and Hall effect measurements performed on this alloy are also reported. (orig.).

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The magnetic excitations of the Kondo compound CePd{sub 2}Si{sub 2} below its Neel temperature (T{sub N} = 10 K) have been studied by inelastic neutron scattering. At T = 1.6 K the data are best represented by two dispersive inelastic modes. Their linewidth ({proportional to} 0.5 meV) indicates substantial broadening, which is ascribed to Kondo-type local fluctuations. (orig.).

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The application of medium energy ion scattering in combination with channelling and blocking to the study of the initial stages of palladium silicide formation is discussed. After a brief description of the experimental arrangement and method, the effects on the Rutherford backscattering spectra of depositing small quantities of palladium on clean Si(111) are reported. The uniformity and thermal stability of thin palladium silicide films grown at room temperature were measured. Finally, channelling and blocking results were used to carry out a structural analysis of thin epitaxial Pd/sub 2/Si layers.

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Experimental data in the hybridised compound YbPd{sub 2}Si{sub 2} is compared with the results obtained with a recently proposed hybridisation model, based on the ''large-degeneracy expansion'' approximation, which takes into account the crystal field splittings of the rare earth ion energy levels. With a unique set of parameters, satisfactory agreement is simultaneously obtained for the thermal variation of the electronic specific heat, of the magnetic susceptibility and of the electric field gradient at the Yb site, as well as for the field variation of the low temperature magnetisation. (orig.).

Science.gov (United States)

In this study, different proportions of silver-palladium alloy used as an inner electrode are adopted to fabricate (Zn,Mg)TiO3-based multilayer ceramic capacitors. Effects of sintering temperature, and measuring frequency on the dielectric properties of the samples with different proportions of the Pd-Ag inner electrode are investigated. The continuity of the inner electrode and the proportion of Pd-Ag of the inner electrode of samples sintered at different temperatures play important roles in determining the dielectric properties.

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The total and differential atomic pair-correlation functions of an icosahedral (quasicrystalline) solid were determined for the first time, directly by the differential anomalous-x-ray-scattering technique using synchrotron radiation. The observed atomic distances involving uranium atoms in icosahedral Pd/sub 58.8/U/sub 20.6/Si/sub 20.6/ suggest the presence of a quasicrystalline sublattice with vertex decoration. The pair distribution functions in the icosahedral and amorphous phases are similar up to the second-nearest neighbors, or up to 6 A-circle.

International Nuclear Information System (INIS)

Crystalline Pd_9Si_2 possesses an orthorhombic structure (Pnma) that is characterized by augmented triangular prismatic coordination of the silicon atoms such as that which occurs in several metal-rich transition-metal silicides. Recent neutron diffraction results for deuterium solution in this crystalline phase have indicated that deuterium occupies only one type of interstice, i.e., a Pd-defined pyramidal site in a four-fold position situated on a quadrilateral face of an empty triangular prism. The vibrational dynamics of both H and D located at this site were investigated by neutron vibrational spectroscopy. The low-temperature density of states (DOS) of H in Pd_9Si_2H_0_._2_5 indicates three well-defined optic vibrations located at 49.4, 67.2 and 75.5 meV. The lowest-energy feature is assigned to the normal-mode vibration perpendicular to the pyramidal base and the two higher-energy features are assigned to the two ...

Science.gov (United States)

An x-ray diffraction approach has been developed for determination of the kinetics of growth of Pd/sub 2/Si layers. Epitaxial Pd/sub 2/Si films were grown on Si(111) substrates over a temperature range of 160-222/sup 0/C by a solid-state reaction between the substrates and the Pd overlayers. The parabolic rate equation was verified and rate constants showed Arrhenius behavior with an activation energy E/sub a/ = 1.06 eV and prefactor k/sub 0/ = 7 x 10/sup -4/ cm/sup 2//s. The low value of E/sub a/ suggests a short-circuit diffusion mechanism. It is reasonable to expect that impurities and microstructure may play important roles in the growth process. Impurity levels in the specimens were evaluated by analytic techniques suited to thin-film study: Rutherford backscattering spectrometry, secondary ion mass spectrometry, and Auger electron spectrometry. No impurities were present at concentrations approaching 1 at. %. Some O, ...

International Nuclear Information System (INIS)

Ab initio calculations of the electronic structure were performed for the silver palladium oxide, Ag_2PdO_2, by the full potential mixed linearized augmented plane wave and augmented plane wave plus local orbitals method (mixed LAPW/APW+lo) within the density functional theory and using the generalized gradient approximation (GGA96, Phys. Rev. Lett. 77 (1996) 3865) for the exchange-correlation potential. The lattice parameters were calculated from the ground-state total energy versus volume curve, and are in good agreement with the available experimental results. Our calculations of band structure predicted that the compound Ag_2PdO_2 has indirect band gap, and the Pd 4d states strongly hybridize with the O 2p states all over the valence bands and conduction bands. The valence bands are composed mainly of Ag, Pd 4d states and O 2p states, while the conduction bands consist mainly of the ...

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Full text: Semiconductor detectors coated with boron or lithium compounds have been studied for neutron detection for decades but, until recently, have been limited to thermal neutron detection efficiencies of less than 5%. We reported previously on development and simulation studies of perforated detectors whose perforations are filled with neutron-reactive material in order to produce higher detection efficiencies. Incorporation of bare and cadmium-backed detectors into battery-powered devices with low-power electronics enables us to produce compact personal neutron dosimeters that provide LED readout of counts, which can be related approximately to neutron dose. We report here on experimental studies with such compact devices; devices capable of direct readout in dose units are anticipated. The thermal and epithermal neutron flux densities from the tangential beam tube of the TRIGA Mark II reactor at Kansas State University were measured. Then, thermoluminescent ...

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A method for detecting electrons emitted as secondary particles by photon incidence to a specimen, as well as a method of using the photons emitted by electron incidence as detecting particles are explained. Pd-Si(100)2{times}1 system is adopted for a case study of using photo-electron spectroscopy where synchrotron emitted light in soft X-ray region is used as the incident light. Pd atoms are deposited little by little on clean Si surface to investigate the electron structure of the surface, and the interface electron structure after bonded formation of Pd(thin film)-Si(substrate) is estimated. Radiation soft X-ray spectroscopy is employed to observe the real state of the bonded interface of Pd(thin film)-Si(substrate) prepared by depositing Pd film in a short period of time. In the case of radiation soft X-ray spectroscopy with electron beam excitation, bonded system of thin film ...

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Mechanisms and associated energetics for adatom diffusion on the (100) and (110) surfaces of Ni, Cu, Rh, Pd, and Ag are investigated. Self-diffusion was studied on (100) and (I 10) surfaces of Ni, Cu, Pd and Ag using corrected effective medium method (CEM) and approximation to CEM used for molecular dynamics and Monte Carlo studies (MD/MC-CEM). Self-diffusion on Pd(100), Ag(100), Ni(110), Cu(110), Pd(110), and Ag(110) is accomplished by classical diffusion: the adatom hops from its equilibrium adsorption site over an intervening bridge site to an adjacent equilibrium site. Self-diffusion on Ni(100) and Cu(100) proceeds by atomic-exchange diffusion: the adatom on the surface displaces an atom in the first surface layer. Aside from explicit inclusion of the kinetic-exchange-correlation energy, it is critical to include enough movable atoms in the calculation to insure correct energetics. Distortions ...

Science.gov (United States)

New tetradentate N(2)O(2) donor Schiff bases and their mononuclear Co(II), Ni(II), Cu(II), and Pd(II) complexes were synthesized and characterized extensively by IR, (1)H-, (13)C-NMR, mass, ESR, conductivity measurements, elemental and thermal analysis. Specifically the magnetic and electronic spectral measurements demonstrate the octahedral structures of cobalt(II), nickel(II) complexes and square planar geometries of copper(II), palladium(II) complexes. All the ligands and complexes were screened for their in vitro antibacterial activity against two gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) and two gram-negative bacteria (Escherichia coli, Klebsiella pneumonia). In this study, Pd(II) complexes exhibited potent antibacterial activity against B. subtilis, S. aureus whereas other metal complexes also exerted good activity towards all tested strains even than standard drugs streptomycin and ampicillin. PMID:21297294

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The available experimental data on the specific heat, magnetic susceptibility, magnetization, valence, NMR Knight shift and relaxation rate, and the quadrupolar moment of YbPd{sub 2}Si{sub 2} are examined within the framework of the single-ion Anderson model. Such an analysis has previously given excellent agreement between theory and experiment for numerous other light heavy-fermion compounds, where crystalline fields do not play a dominant role. For YbPd{sub 2}Si{sub 2}, substantial crystalline-field splittings make difficult a quantitative comparison with existing exact solutions of the Anderson model. Inconsistencies with the interpretation that a nearly degenerate ground quadruplet determines the low-temperature thermodynamics are pointed out. It is concluded that at least three of the four Kramers doublets participate in the low-{ital T} properties. These three doublets should have a splitting of the order of the Kondo temperature, i.e., ...

International Nuclear Information System (INIS)

We report the results of neutron-diffraction experiments on CeM_2Si_2 (M = Ag,Au,Pd,Rh) which were performed to explore the role of valence fluctuations and 4f hybridization in the magnetic ordering of cerium compounds. All four order antiferromagnetically, the first three exhibiting structures consisting of ferromagnetic layers with moments perpendicular to the layers, which are believed to be characteristic of 4f-4f interactions mediated through hybridization with conduction electrons. CePd_2Si_2 has an anomalously small moment (0.62#mu#/sub B/) in the ordered state. CeAg_2Si_2 exhibits an incommensurate longitudinal, static magnetization wave with moment and propagation direction along the a axis. The fourth compound, CeRh_2Si_2, has the highest known transition temperature (39 K) reported for cerium ordering; it exhibits another second-order transition at 27 K to a complex commensurate structure with modulated moments. The results are ...

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Excellent silicided shallow p{sup +}n junctions have been successfully achieved by the implantation of BF{sub 2}{sup +} ions into thin Pd{sub 2}Si films on Si substrates to a dose of 5 {times} 10{sup 15} cm{sup {minus}2} and subsequent low temperature (even at 550 C) furnace annealing. The formed junctions have been characterized for respective implantation conditions. In this experiment, the implant energy is the key role in obtaining a low leakage diode. Reverse current density of about 3 nA/cm{sup 2} and an ideality factor of about 1.05 can be attained by the implantation of BF{sub 2}{sup +} ions at 80 keV and subsequent annealing at 550 C. The junction depth is about 0.09 {mu}m, measured by the spread resistance method. As compared with the results of unimplanted specimens, the implantation of BF{sub 2}{sup +} ions into a thin Pd{sub 2}Si layer can stabilize the silicide film and prevent it from forming islands during high temperature ...

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In order to improve the long term reliability of lead-salt diode lasers, ohmic contacts of multilayer, thin-film structures consisting of In plus Au, Pt, Ni, and Pd have been studied. Diode lasers of PbSnTe fabricated with a variety of contacts were tested during room-temperature storage and during accelerated aging tests. The results show that contact reliablility can be improved when multiple overlapping films are used. After 4500 h of baking at 60 /sup 0/C, lasers with In-Au-Pd-Au contacts on both sides showed the least resistance increase (10%). For lasers with In-Au-Pt-Au contacts, 1 h of baking at 60 /sup 0/C is equivalent to 2 d storage at room temperature. Extrapolating these results, a 70% increase in contact resistance is expected for this type of laser after 9000 d of storage at room temperture. Our data also suggests that a smaller increase in contact resistance can be expected for lasers fabricated with In-Au-Ni-Au and ...

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Eu 4f electronic structures of a temperature-induced valence transition system EuPd{sub 2}Si{sub 2} have been investigated by bulk-sensitive high-resolution photoemission spectroscopy at temperatures from 20 to 300 K. The bulk Eu{sup 2+} 4f component is definitely distinguished from two surface Eu{sup 2+} 4f components. The changes in the spectral intensity of the bulk Eu{sup 2+} and Eu{sup 3+} 4f configurations and in the energy separation between these states are observed in the temperature dependent photoemission spectra. These temperature dependences are related to the valence transition of EuPd{sub 2}Si{sub 2}. The Eu mean valence is evaluated to be 2.75{+-}0.03 at 20 K and 2.30{+-}0.05 at 300 K. These values are in good agreement with those evaluated from Moessbauer and Eu L{sub III}-edge X-ray absorption measurements.

International Nuclear Information System (INIS)

With "1"5"1Eu-Moessbauer spectroscopy and other methods the complex magnetic properties of Eu_2PdSi_3, arising from the two crystallographically different lattice sites of the Eu"2"+ ions, have been already studied. Here we study the impact of magnetic dilution of the magnetic Eu"2"+ sites by non-magnetic Y"3"+ ions. A previous specific heat study has found reduced magnetic ordering temperatures with strong indication of disorder effects like in magnetic spin glasses. Here we provide from "1"5"1Eu-Moessbauer spectroscopy detailed information of the impact of Y"3"+ substitution on the magnetic properties of the two lattice sites, well distinguishable in the "1"5"1Eu-spectra. Since the substitution of the larger Eu"2"+ ions by the smaller Y"3"+ ions is connected with a lattice contraction, we also applied high pressure to the Eu_2PdSi_3 sample and observed drastic changes in the magnetic properties originating from a valence transition towards ...

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The magnetic ordering temperature of some rare-earth-based heavy-fermion compounds is strongly pressure dependent and can be completely suppressed at a critical pressure, p{sub c}, making way for novel correlated electron states close to this quantum critical point. We have studied the clean heavy-fermion antiferromagnets CePd{sub 2}Si{sub 2} and CeIn{sub 3} in a series of resistivity measurements at high pressures up to 3.2 GPa and down to temperatures in the mK region. In both materials, superconductivity appears in a small window of a few tenths of a GPa on either side of p{sub c}. We present detailed measurements of the superconducting and magnetic temperature-pressure phase diagram, which indicate that superconductivity in these materials is enhanced, rather than suppressed, by the closeness to magnetic order. (author)

Science.gov (United States)

Amorphous Pd/sub 80/Si/sub 20/ was irradiated with fast neutrons (>1 MeV) to a fluence of 5 x 10/sup 20/ neutrons/cm/sup 2/. X-ray scattering intensities were measured before and after the irradiation with monochromatic Cu-K..cap alpha../sub 1/ rays. Scattered intensities for s>0.4 A/sup -1/ (s=2 sintheta/lambda) proved unaffected, while intensities were found remarkably enhanced for s<0.4 A/sup -1/ after the irradiation, i.e., in the small-angle region and the leading edge of the first halo. The results are discussed in relation to the structural anomalies in amorphous solids.

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Specimens of glassy Pd{sub 80}Si{sub 20} were irradiated at temperatures below 100K with 3.5 MeV krypton ions. After irradiation, changes in the sound velocity were measured at 80 K without warm-up by Brillouin scattering. The sound velocity decreased with increasing ion fluence and exponentially approached a saturation value of -4.7%. The change in the shear elastic modulus per unit concentration n of defects was estimated to be d(ln C)/dn = -9.4 to -4.7. The results of the present study are compared with changes in the elastic properties predicted recently by an interstitialcy model for glassy metals, and with the elastic properties of glassy metals after thermal treatment.

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We have performed polarized neutron diffraction measurements on the intermediate valence compound CePd{sub 3} using the D3 spectrometer at the ILL. The results show that at low temperatures, 1.7 K, as well as at 100 K, the field-induced magnetic amplitudes measured in a field of 4.6 T could be interpreted in terms of two contributions: a 4f-type contribution with a Ce{sup 3+} form factor, and an extra delocalized contribution (relatively narrow in q-extent). In particular, we find that the values of the 4f moment deduced from the extrapolation of the neutron data to Q=0 are systematically lower than the values deduced from bulk magnetization measurements performed on the same sample. This difference can be ascribed to a possible positive polarization of the conduction band which is similar at both temperatures.

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This paper describes the search for new potential chemotherapeutic agents based on transition metal complexes with planar ligands. In this study, palladium polypyridyl complexes were synthesized and characterized by elemental analysis, NMR, UV-VIS and IR spectroscopies. The interaction of the complexes with DNA was also investigated by spectroscopic methods. All metal-to-ligand charge transfer (MLCT) bands of the palladium polypyridyl complexes exhibited hypochromism and red shift in the presence of DNA. The binding constant and viscosity data suggested that the complexes [PdCl{sub 2}(phen)] and [PdCl{sub 2}(phendiamine)] interact with DNA by electrostatic forces. Additionally, these complexes induced an important leishmanistatic effect on L. (L.) mexicana promastigotes at the final concentration of 10 {mu}mol L{sup -1} in 48 h. (author)

International Nuclear Information System (INIS)

The solid solutions Eu(Ir_1_-_xPd_x)_2Si_2, which exist for 0#<=#x#<=#0.125 and 0.75#<=#x#<=#1, cristallize with the tetragonal ThCr_2Si_2-type structure. The variation of the europium valence with composition has been thoroughly studied at temperatures 4.2#<=#T#<=#293 K by "1"5"1Eu Moessbauer resonance. For 0#<=#x#<=#0.125 the europium valence at room temperature decreases as x increases. For 0.75#<=#x#<=#1 the valence transition temperature Eu"3"+#->#Eu"2"+ increases as x increases. (orig.).

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Changes in mass density of amorphous Pd{sub 80}Si{sub 20} were monitored in situ during irradiation with He{sup 2+} and H{sup +} ions at temperatures below 100 K and during subsequent thermal treatment. The mass density decreased with increasing ion fluence and exponentially approached a saturation value of -1.2%, corresponding to a recombination volume of 190 atomic volumes. The initial swelling rate was 2.3 atomic volumes/displaced atom. The mass density of the irradiated material increased during subsequent thermal treatment, and the irradiation-induced decrease of the mass density recovered completely at room temperature.

International Nuclear Information System (INIS)

The compound GdPd_2Si, which is reported to order antiferromagnetically at 13 K, has been investigated by heat capacity and electrical resistivity measurement in the presence of external magnetic fields. In contrast to an earlier report, the zero-field heat capacity and resistivity data indicate two magnetic transitions at 13 and 17 K. The external magnetic field substantially influences the resistivity and heat capacity of the compound around the magnetic ordering temperature. The magnetocaloric effect, which is calculated from in-field heat capacity data, is quite large around the magnetic transition temperature. The magnetoresistance is also large near the magnetic ordering temperature. The metamagnetic transition is observed for 10 kOe magnetic field both in magnetocaloric and in magnetoresistance data. The metamagnetic transition strongly influences the magnetocaloric effect and magnetoresistance, which is large in this compound. (author). Letter-to-the-editor

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The cross-over from a magnetically ordered to a non-magnetic spin liquid state has been investigated in a series of resistance measurements under hydrostatic pressures of up to 30 kbar and at temperatures down to below 200 mK in the heavy fermion antiferromagnet CePd{sub 2}Si{sub 2}. The electrical resistivity changes dramatically with increasing pressure. Near the critical pressure, at which the magnetic ordering temperature is extrapolated to zero, it exhibits a quasi-linear variation over two orders of magnitude in temperature. This non-Fermi liquid form of {rho}(T) extends down to the onset of a new superconducting transition below 430 mK. (orig.).

Energy Technology Data Exchange (ETDEWEB)

We present the results of the low-temperature specific heat of Kondo compound Ce{sub 3-x}La{sub x}Pd{sub 20}Si{sub 6} (x=0, 1, 2 and 2.7) and its magnetic-field dependence for x=0. The magnetic part of specific heat divided by temperature, C{sub m}/T, for x=0 makes a peak as high as 9 J/mol Ce K{sup 2} at 0.2 K. On the other hand, C{sub m}/T for the other x`s keeps increasing monotonically below 0.2 K and the Fermi-liquid ground state is not realized even in diluted samples. It was found that the magnetic field strongly depresses C{sub m}/T at low temperatures. (orig.).

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Internal friction of amorphous Pd/sub 80/Si/sub 20/ metal doped with hydrogen or deuterium was measured with a specially designed apparatus using amorphous metal sheet as a part of the electric oscillating circuit. Two peaks in Q/sup -1/ curve are observed. Applying the peak shift method to the first Snoek-like peak, we can determine the relaxation time from which the microdiffusion coefficient can be calculated. The obtained microdiffusion coefficient is about 10/sup -14/ m/sup 2//s at 200 K, being comparable with the macrodiffusion coefficient obtained from the releasing method. It can, however, not elucidate the hydrogen isotopic effect on the peak temperature of Q/sup -1/ curve, the activation energy for relaxation and the relaxation time from the present work because of the broadness of obtained Q/sup -1/ curve.

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An x-ray diffraction technique for determining thin-film thickness is presented which should prove to be a valuable alternative to the array of spectroscopies (Rutherford backscattering spectrometry, Auger electron spectroscopy, etc.) currently favored for these measurements. Some of the virtues of this x-ray diffraction approach are its nondestructive nature, fast data acquisition rate (enabling in situ observations), thickness resolution better than 5 nm, and conventional equipment requirements. Results are shown for Pd/sub 2/Si thin films grown during isothermal annealing of Pd coatings (100 nm) on Si at 200 /sup 0/C for various amounts of time. A comparison of these x-ray measurements with Rutherford backscattering spectrometry data taken from the same specimens is used to demonstrate the validity of the x-ray technique.

International Nuclear Information System (INIS)

The magnetic susceptibility and high-field magnetization have been measured for the intermediate valence system Eu(Pd_1_-_xPt_x)_2Si_2 with 0#<=#x#<=#0.15. A first-order valence transition is observed for all the compounds under high field of 100 T at low temperatures. This valence transition is of first order accompanied with a large hysteresis, which is in contrast to a continuous valence change against temperature. Based on the interconfigurational fluctuation (ICF) model, the temperature- and field-induced valence transitions are discussed. It is found that a first-order valence transition can be induced by magnetic field, even if the system shows a continuous valence transition against temperature. Metamagnetic behavior at finite temperatures is also understood qualitatively by the ICF model. copyright 1997 The American Physical Society.

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The electronic structures of platinum group elements (Ru, Os, Rh, Ir, Pd, and Pt) silicides have been calculated. Ir{sub 3}Si{sub 5} is a semiconductor with the direct gap of 1.14 eV. Among monosilicides, RuSi and OsSi with the FeSi-type structure are semiconductors with the gap values of 0.21 and 0.41 eV but RhSi, IrSi, PdSi, and PtSi with the MnP-type structure are metals. No semiconducting compounds can be found in other platinum group elements silicides other than known Ru{sub 2}Si{sub 3}, Os{sub 2}Si{sub 3}, and OsSi{sub 2}.

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Thin Pt, Pd, Pt/sub 2/Si, PtSi, Pd/sub 2/Si, Ni, Mo, W, Nb, Ti, V films deposited on Si single crystal were treated by using electron beam pulses of 60 ns duration in the 0.4-4 J/cm/sup 2/ energy density range. Irradiation of these structures produces at the same time many phases. Post-thermal annealing of the reacted layer induces the formation of a stable phase, the same obtained by only thermal treatment in a conventional furnace. A linear relationship between the energy density range and the lowest eutectic temperature of the compounds formed has been found. Further SEM observations seem to identify a liquid layer from which the phases are forming by subsequent fast cooling.

International Nuclear Information System (INIS)

The intermediate valent behaviour of YbPd_2Si_2 has been studied under pressure in the temperature range from 1.2 K to 90 K by using the 84 keV Moessbauer transition in "1"7"0Yb. At 54 kbar and 4.2 K we obtain an increase of the electric field gradient (EFG) by a factor of #approx =# 3. In addition, the EFG varies strongly with temperature, in contrast to the behaviour at ambient pressure. At 1.2 K a change of the hyperfine pattern is observed indicating a magnetic character of the Yb ion. These results provide evidence of a pressure induced change of the valence state close to 3+. (orig.).

Science.gov (United States)

Channeling effect measurements have been employed to investigate radiation damage produced by 100-keV Ar ions in preferred oriented polycrystalline metal-silicide layers, such as Pd/sub 2/Si and NiSi/sub 2/ layers formed on single-crystalline Si. For room-temperature implantation, an amount of the damage in Pd/sub 2/Si layers was found to saturate at doses between 3 x 10/sup 14/ and 1 x 10/sup 17/ ions/cm/sup 2/, where the minimum aligned yield of 1.5-MeV He ions was nearly 40% of the random one. On the contrary, it was observed that the NiSi/sub 2/ layers became amorphous at doses higher than 3 x 10/sup 15/ ions/cm/sup 2/. These results were confirmed by the reflection electron diffraction analyses.

International Nuclear Information System (INIS)

Cerium L_3 XANES (x-ray-absorption near-edge-structure) spectra were analyzed to separate Ce moment contributions and mixed valence (MV) in complex magnetic silicides CePd_2_-_xMn_xSi_2 (0#<=#x#<=#2). The Ce valence mixing does not vary linearly with x, but increases rapidly for x#>=#1.5. The associated moment collapse correlates with pronounced deviations of the unit-cell volume from Vegard law and the onset of structural instability. Reorientation of [001] Mn 3d antiferromagnetic order for x<2 appears to rapidly suppress the weak Ce valence mixing coexisting with antiferromagnetic order in CeMn_2Si_2.

Energy Technology Data Exchange (ETDEWEB)

Three-dimensional dynamics of a compact toroid (CT) plasmoid, which is injected into a magnetized target plasma region is investigated by using magnetohydrodynamic (MHD) numerical simulations. It is found that the process of the CT penetration into this region is much more complicated than what has been analyzed so far by using a conducting sphere (CS) model. The injected CT suffers from a tilting instability, which grows with the similar time scale as the CT penetration. The instability is accompanied by magnetic reconnection between the CT magnetic field and the target magnetic field, which disrupts the magnetic configuration of the CT. Magnetic reconnection plays a role to supply the high density plasma initially confined in the CT magnetic field into the target region. Also, the penetration depth of the CT high density plasma is examined. It is shown to be shorter than that estimated from the CS model. The CT high density plasma is decelerated mainly by the Lorentz force of the ...

CERN Document Server

We study from a critical perspective several quantum-electrodynamic phenomena commonly related to vacuum electromagnetic (EM) fluctuations in complex media. We compute the resonance-shift, the spontaneous emission rate, the local density of states and the van-der-Waals-Casimir pressure in a dielectric medium using a microscopic diagrammatic approach. We find, in agreement with some recent works, that these effects cannot be attributed to variations on the energy of the EM vacuum but to variations of the dielectric self-energy. This energy is the result of the interaction of the bare polarizability of the dielectric constituents with the EM fluctuations of an actually polarized vacuum. We have found an exact expression for the spectrum of these fluctuations in a statistically homogeneous dielectric. Those fluctuations turn out to be different to the ones of normal radiative modes. It is the latter that carry the zero-point-energy (ZPE). Concerning spontaneous ...

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Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence ...

International Nuclear Information System (INIS)

Results from three separate experiments that have some relevance to bound residues are reported. In the first, "1"4C-labelled paraquat was lost when applied to soil in the field, about 26% of the radioactivity disappearing in 15 months, whereas in laboratory incubation studies there was no loss of radioactivity in one year. Two possible explanations are (i) that there was photolytic decomposition in the field, (ii) the preparation of the soil for the laboratory study upset the microbial ecology of the soil to the detriment of organisms that can degrade paraquat. In an experiment with "1"4C-labelled isoproturon, there was an indication that there was slightly more "1"4C in the unextractable humin fraction in soil in which wheat plants were grown than in bare soil. Work in the UK, Federal Republic of Germany and in Switzerland has shown that the phytotoxicity of residues of atrazine, carbetamide, chloridazone, propyzamide, simazine, lenacil, monolinuron, linuron, ...

International Nuclear Information System (INIS)

Contrary to previous plans for the preparation of diagnostic systems for D-T break-even experiments in the Tokamak Fusion Test Reactor (TFTR), it now appears that a limited Q#approx#1 demonstration can be carried out without constructing a close-fitting igloo radiation shield around the tokamak. In order to assess the impact of D-T operation of TFTR without an igloo shield, particularly with regard to hardening of diagonstic systems, we have mapped neutron and gamma fluxes inside the test cell and test cell basement, using a variety of radiation measurements. The measurements are sufficiently detailed to resolve massive hardware components, such as neutral beams and shielded diagnostic systems, and can be used to predict local fluxes. By comparing the measurements with transport code calculations for the case of a bare tokamak, we conclude that the models have substantially overestimated fluxes both inside and outside the TFTR shield walls. It may be possible to ...

Energy Technology Data Exchange (ETDEWEB)

Infrared astronomical instruments require absorptive coatings on internal surfaces to trap scattered and stray photons. This is typically accomplished with any one of a number of black paints. Although inexpensive and simple to apply, paint has several disadvantages. Painted surfaces can be fragile, prone to shedding particles, and difficult to clean. Most importantly, the vacuum performance is poor. Recently a plasma enhanced chemical vapor deposition (PECVD) process was developed to apply thick (30 {micro}m) diamond-like carbon (DLC) based protective coatings to the interior of oil pipelines. These DLC coatings show much promise as an infrared black for an ultra high vacuum environment. The coatings are very robust with excellent cryogenic adhesion. Their total infrared reflectivity of < 10% at normal incidence approaches that of black paints. We measured outgas rates of <10{sup -12} Torr liter/sec cm{sup 2}, comparable to bare stainless steel.

International Nuclear Information System (INIS)

The purpose of this text is to train engineers and technologists not just to understand corrosion but to control it. Materials selection, coatings, chemical inhibitors, cathodic and anodic protection, and equipment design are covered in separate chapters. High-temperature oxidation is discussed in the final two chapters ne on oxidation theory and one on controlling oxidation by alloying and with coatings. This book treats corrosion and high-temperature oxidation separately. Corrosion is divided into three groups: (1) chemical dissolution including uniform attack, (2) electrochemical corrosion from either metallurgical or environmental cells, and (3) stress-assisted corrosion. Corrosion is logically grouped according to mechanisms rather than arbitrarily separated into different types of corrosion as if they were unrelated. For those university students and industry personnel who approach corrosion theory very hesitantly, this text will present the electrochemical reactions responsible ...

Energy Technology Data Exchange (ETDEWEB)

The application of the LBB technology to the newly constructed PWRs has been approved in Korea for several high energy systems that can meet rigorous acceptance criteria. The LBB evaluation had been initiated for Yong-Gwang 3 and 4 units (YGN 3 and 4) which are in service, and subsequently performed for Ul-Chin 3 and 4 units (UCN 3 and 4) which are in construction. The LBB application in Korea is based on the USNRC requirements. The LBB evaluation for YGN 3 and 4 is to eliminate the dynamic effects associated with the postulated DEGB from design basis loads as well as to eliminate pipe whip restraints and jet impingement barriers. There were several issues on the application of LBB to the primary coolant loop and the pressurizer surge line. Of concern were material properties of carbon steel for the primary coolant loop, estimation of crack opening area at the pipe-to-nozzle interface considering the asymmetry, and the leakage crack size which barely meets the ...

Energy Technology Data Exchange (ETDEWEB)

A residue of the sugar industry can be used in revegetation programs on metal contaminated sites. - Phytostabilisation of bare heavily contaminated substrate, such as abandoned mine sites, is considered a very appropriate technology in order to diminish erosion and dispersion of contaminants into the surroundings. In this short-term pot study, application of industrial sugar residue (ISR), a waste product of the sugar industry, proved to ameliorate spoils conditions for plant performance by elevating pH and immobilising several metals. Although arsenate concentrations were positively correlated to spoil pH and spoil treatment with ISR mobilised As, growth of both Phaseolus vulgaris and Holcus lanatus improved significantly after applications of 3.75 g ISR kg{sup -1} dry spoil. Nutrient uptake from the substrate, with the exception of potassium, was elevated by ISR. As a remediation technique ISR application could be effective although in As-contaminated sites ...

International Nuclear Information System (INIS)

Fully relativistic full-potential density functional calculations with an all-electron linearized augmented plane wave plus local orbitals method have been performed to investigate the electronic and geometric structures of atomic carbon, nitrogen, and oxygen chemisorption on the (1 0 0) surface of #delta#-Pu. For all chemisorption processes, the center adsorption site is found to be the most preferred site with chemisorption energies of 7.964, 7.665, and 8.335 eV for the C, N, and O adatoms, respectively. The respective optimized distances of the C, N, and O adatoms from the surface were found to be 0.26, 0.35, and 0.48 A. The work functions and the net magnet moments, respectively, increased and decreased in all cases compared with the bare #delta#-Pu (1 0 0) surface. In particular, the work function shift is largest for the least preferred top site and lowest for the most preferred center site. A detailed analysis of partial charges inside the atomic spheres, ...

Energy Technology Data Exchange (ETDEWEB)

Osteonecrosis (ON) of the hip joint remains an unsolved therapeutical problem. Diagnosis of ON of the hip has been improved by the technical progress of imaging modalities and better understanding pathomorphology. Over a long period only plain radiographs have been available. Scintigraphy and computed tomography contributed to differential diagnosis and early detection of bone necrosis. Diagnosis in an early reversible stage is of importance. Understanding of pathophysiology, early diagnosis and therapeutical approach has been significantly improved by MR imaging. Using the ARCO system all imaging modalities and their diagnostic viability are described in the five ARCO stages. At the end a diagnostic algorithm will be proposed. (orig.) [German] Die Osteonekrose des Hueftgelenks (ON) stellt noch immer ein nicht geloestes therapeutisches Problem dar. Die diagnostischen Moeglichkeiten bei der ON wurden in den letzten Jahren durch technische Fortschritte bei den ...

Energy Technology Data Exchange (ETDEWEB)

The intermetallic phase NiAl is a potential material for high-temperature applications; however, its technical application was prevented so far by its high brittleness at room temperature. This problem may be solved by incorporating relatively high-ductility particles into the NiAl matrix. Controlled crack propagation experiments, tensile and pressure tests were carried out in order to analyze the toughness and deformation characteristics of NiAl composite materials containing niobium or molybdenum particles at room temperature and in ambient atmosphere. Both the niobium and the molybdenum particles increase the toughness as compared to the pure NiAl matrix, but no ductilisation was observed in the composite materials investigated. Model experiments in consideration of experimental data suggest, hovewer, that the toughness and ductility of NiAl may be enhanced by optimizing the microstructural and production parameters of the incorporated ductile particles. (orig.) [Deutsch] Die ...

Energy Technology Data Exchange (ETDEWEB)

Tanzania has recently developed a comprehensive environmental policy which has put high priority on several specific environmental issues. One of the issues is the quality of waste water. A special priority is given to the pollution from the sisal industry. The East-African agro-industries generate very large quantities of organic residues from production and processing of different crops. These residues form a major contribution to the pollution of air, soil and waterways, but, at the same time they constitute a large potential for production of bioenergy through anaerobic digestion as well as potential substrate for other biological fermentation processes. Generally, these residues are regarded as having no or very little value and the different disposal methods are mainly a matter of getting rid of the waste. The generation of residues are very often concentrated on few large units, which makes the exploitation of these resources feasible in large scale biogas systems. Typically the ...

International Nuclear Information System (INIS)

A comparative study by Eu-L_I_I_I X-ray absorption and "1"5"1Eu-Moessbauer spectroscopy is presented for the EuPd_2_-_xAu_x Si_2 series. Possible ways to distinguish between mixed-valent behaviour and final-state effects in the L_I_I_I-edge spectra are discussed.

Science.gov (United States)

The efficiency of two thin-film diffusion barriers to be used in silicide/aluminum metallization schemes for silicon integrated circuits were evaluated. Control samples of Si/CoSi{sub 2}/Al and Si/Pd{sub 2}Si/Al, and test samples of Si/CoSi{sub 2}/Ta{sub 2}N/Al, Si/CoSi{sub 2}/W/Al and Si/Pd{sub 2}Si/Ta{sub 2}N/Al were used for sheet resistance, X-ray diffraction, Rutherford backscattering, and Auger-electron spectroscopic measurements. TEM studies were carried out on representative samples to examine the nature of the interfaces. Results from the analytical tests indicated that all three types of test samples are resistant to gross diffusion and intermixing of Co, Pd, Al and Si. They also showed that in the control samples, annealing causes interdiffusion of these species, necessitating the presence of a diffusion barrier. For test contacts, results demonstrated that although diffusion barriers may be successful in ...

UK PubMed Central (United Kingdom)

The metabolism of pentose-phosphate was investigated in Plasmodium falciparum-infected normal and glucose-6-phosphate dehydrogenase (G6PD)-deficient human red blood cells in vitro. 5'-Phosphoribosyl-1-pyrophosphate...Full Text Available

Science.gov (United States)

A general palladium-catalyzed carbonylative Sonogashira coupling of benzyl chlorides with terminal acetylenes has been established. Depending on the alkyne 1,4-diaryl-3-butyn-2-ones or substituted furanones are obtained in moderate to good yields. Best catalytic performance is achieved applying a mixed Pd(PPh(3))Cl(2)/P(OPh)(3) catalyst system. PMID:21968528

British Library Electronic Table of Contents (United Kingdom)

Biased above threshold (VT), pulsed photocurrent (u) measurements on windowed silicon Pd gate MOS capacitors are shifted (DV) negatively by H2/N2, whereas Au gates shift positively under NO2/air. Below VT, the shifts are reversed by adjustments of interface state population. Minor temperature increases may coax the device from inversion to depletion, inducing sign reversal of the chemical response.

Energy Technology Data Exchange (ETDEWEB)

X-ray diffraction was used to monitor the {ital in} {ital situ} reaction of Pd deposited on Si(111) at room temperature. An ordered silicide forms spontaneously beneath a poorly ordered overlayer. It is commensurate and strained at low coverage, but relaxes to an unstrained state above a critical thickness of 18 A. During both phases of growth sustained intensity oscillations are seen that correspond to a layerwise consumption of the substrate at the buried interface.

Energy Technology Data Exchange (ETDEWEB)

A massively-parallel ab initio computer code, which uses Gaussian bases, pseudopotentials, and the local density approximation, permits the study of transition-metal systems with literally hundreds of atoms. We present total energies and relaxed geometries for Ru, Pd, and Ag clusters with N = 55, 135, and 140 atoms; we also used the DMOL code to study 13-atom Pd and Cu clusters, with and without hydrogen. The N = 55 and 135 clusters were chosen because of simultaneous cubo-octahedral (fcc) and icosahedral (icos) sub-shell closings, and we find icos geometries are preferred. Remarkably large compressions of the central atoms are observed for the icos structures (up to 6% compared with bulk interatomic spacings), while small core compressions ({approx} 1 %) are found for the fcc geometry. In contrast, large surface compressive relaxations are found for the fcc clusters ({approx} 2-3% in average nearest neighbor spacing), while the icos surface ...

UK PubMed Central (United Kingdom)

Rapidly developing changes in the short-circuiting current (Isc), conductance (G), and potential (PD) of turtle bladders in Na-rich or Na-free media are seen after the mucosal addition, at 10 nM, of...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A new technology called a self-aligned metal-silicide process is described in the fabrication of silicon detectors. It has been found that this technology improves both detector yield and leakage current. The use of a metal silicide also gives a lower contact resistance and, depending on the thermal process, a controllable junction depth, which may be essential in the integration of detectors and their electronics.

Energy Technology Data Exchange (ETDEWEB)

Purpose: To evaluate the success rates of the implantation of stent grafts in the treatment of peripheral aneurysms. Materials and methods: in 13 patients with 15 aneurysms at the common iliac artery (n = 6), external iliac artery (n = 1), hypogastric artery (n = 2), femoral artery (n = 2) or popliteal artery (n = 4), implantation of dacron-covered nitinol stents was performed. The patients were followed up for three to 20 months (mean, 8.8 months) with intravenous digital subtraction angiography, CT or colour-coded Doppler sonography. Results: In all cases, the aneurysm was successfully occluded after stent implantation. In one case with a popliteal aneurysm, kinking of the vessel caused thrombosis of the stent. The stent was successfully reopened. The aneurysm however, had to be surgically treated 9 months later. The primary and secondary patency rates at 6 months were 93% and 100%, respectively. Conclusion: The method described might be an alternative therapy to surgery. There are ...

Energy Technology Data Exchange (ETDEWEB)

In comparison to deterministic criteria, probabilistic reliability indices like interruption frequency and unavailability give a more differentiated insight into reliability in an electrical energy network. One possibility for network planning based on these indices is the definition of limits for customer nodes, another is the monetarisation of reliability in terms of interruption costs. Because of numerous disadvantages, interruption cost methods could not up to now win broad recognition in network planning in Western Europe. A more recent method for the monetarisation of reliability circumventing most of these disadvantages is the insurance system. In this system the customer selects a tariff class in an insurance system, and the utility reimburses its customers in the case of an interruption. In its first section, the paper describes a method for the flexible and realistic optimisation of MV networks. This method based on Genetic optimisation is able to integrate probabilistic ...

Energy Technology Data Exchange (ETDEWEB)

The paper presents fundamental studies on natural biosorption to algae of heavy metals. The investigations were carried out by TU Berlin University in a special research project (Sfb 193, 'Biologische Behandlung industrieller und gewerblicher Abwaesser'). The chlorophyceae C. vulgaris was used as reference alga, and 38 further algae were analzyed with regard to their sorption characteristics for lead, cadmium, nickel and zinc. The most effective algae were the chlorophyceae C. salina, the cyanophyceae S. hofmani and L. taylorii. The biosorption characteristics of C. salina and L. taylorii were investigated in detail. L. taylorii was found to be exploitable successfully in a technical process, so the investigations were extended to include copper. Knowledge about the chemical processes of biosorption is important for any attempt to modify the biosorption characteristics. Experiments on the incorporation of additional functional groups in the cell wall polysaccharides ...

International Nuclear Information System (INIS)

A semirelativistic two-component extended linear augmented plane-wave k#centre dot#p method is described. In order to ensure a high accuracy of the k#centre dot#p method, it is necessary to include into the radial-basis set, which is used for the augmentation of the plane waves, functions that are neither solutions of the Schrodinger equation nor their energy derivatives. The usual scalar relativistic procedure, which is nonlinear in energy, is not applicable to such basis sets. As an alternative, we suggest an approximation to the Foldy-Wouthuysen Hamiltonian that produces an explicitly Hermitean matrix in the augmented plane wave representation. The technique is applied to the calculation of the full dielectric matrix and optical properties of palladium and platinum metals over the photon energy region up to 100 eV. Special attention is paid to the far ultraviolet absorption by the excitations of semicore Pd 4p and Pt 5p and 4f states. A strong effect of local ...

Energy Technology Data Exchange (ETDEWEB)

Diffusion during He/sup +/, Ne/sup +/, and Xe/sup +/ irradiations of trace amounts of Au in melt-spun amorphous Pd/sub 78/Cu/sub 6/Si/sub 16/ has been experimentally investigated. Diffusion constants were measured by following the changes in ion-implanted Au profiles with Rutherford-backscattering spectrometry. Heat treatments and simultaneous irradiations were performed as a function of temperature (533--588 K), ion flux, and ion mass. Total integrated fluences being very small, ion-beam-mixing effects are negligible. More than an order of magnitude enhancement in the diffusion was observed because of irradiations. This enhancement saturates at higher fluxes, the level being independent of ion mass, i.e., independent of collision-cascade parameters. Except at higher temperatures, where the enhancement decreases, the temperature dependence of the diffusion-saturation level is similar to that of the diffusion without irradiation. The data suggest that vacancylike ...

British Library Electronic Table of Contents (United Kingdom)

New palladium(II) and platinum(II) complexes of saccharinate (sac), trans-[Pd(py)"2(sac)"2] (1), cis-[Pt(py)"2(sac)"2] (2), trans-[Pd(3-acpy)"2(sac)"2] (3) and cis-[Pt(3-acpy)"2(sac)"2] (4) (py=pyridine and 3-acpy=3-acetylpyridine) have been synthesized. Elemental analysis, UV-Vis, IR, NMR and TG/DTA characterizations have been carried out. The structures of 1-4 were determined by X-ray diffraction. The palladium(II) and platinum(II) ions are coordinated by two N-bonded sac ligands, and two nitrogen atoms of py or 3-acpy, forming a distorted square-planar geometry. The palladium(II) complexes (1 and 3) are trans isomers, while the platinum(II) complexes (2 and 4) are cis isomers. The mononuclear species in the solid state are connected by weak intermolecular C-H...O hydrogen bonds, C-H...@...

International Nuclear Information System (INIS)

Ternary R_2TSi_3 intermetallic compounds (R=Rare Earth, T=Transition Metal) with hexagonal AlB_2-type crystallographic structure are known because of their interesting physical properties. Pr_2PdSi_3 single crystals were grown by a vertical floating zone method. The compound exhibits congruent melting behavior at a liquidus temperature of about 1770 C. Single crystalline samples show a huge anisotropy at low temperatures due to the crystal electric field effect and order antiferromagnetically below the Neel temperature T_N=2.17 K. This value approximately obeys the linear de Gennes scaling for this class of compounds. The [001] orientation was identified as the magnetic easy axis at room temperature. At lower temperature (#approx#20 K) magnetic easy and hard axes interchange with each other. Two additional magnetic phase transitions were observed at temperatures below 1 K.

Energy Technology Data Exchange (ETDEWEB)

Xe ion irradiation of NiSi, PdSi, and PtSi on Si was performed at various substrate temperatures. The phase formation and mixing behavior of the three monosilicides with their Si substrates are quite different. For NiSi, NiSi/sub 2/ was formed on amorphous Si substrates at 350 /sup 0/C, while NiSi remained stable on crystalline Si substrates even at 400 /sup 0/C. PtSi reacted with Si to form a metastable Pt/sub 4/Si/sub 9/ phase, which decomposed back to PtSi and Si by successive irradiation at higher temperatures. The decomposition of the metastable Pt/sub 4/Si/sub 9/ was easier on crystalline Si substrates than on amorphous substrates. No mixing was observed for PdSi on Si in the temperature range of 35--400 /sup 0/C. The ion mixing results were compared with those from thermal annealing. The importance of demixing of a thermally stable system was explored.

Science.gov (United States)

A knowledge of surface film growth kinetics can be quite useful in the production of materials for uses ranging from protective coatings to microelectronic devices. A technique for determining the kinetics of film growth is presented which should prove to be a valuable alternative to the array of spectroscopies (AES, RBS, etc.) currently favored for these measurements. Some of the virtues of this X-ray diffraction approach are its non-destructive nature, thickness resolution better than 50 {angstrom} and conventional equipment requirements. Results obtained for the growth of Pd{sub 2}Si films during thermal annealing of Pd coatings on Si, indicate parabolic growth over a temperature range of 160-222 C. The rate constant was found to be k{prime} = 7 {times} 10{sup {minus}4} exp ({minus}1.06 eV/kT) cm{sup 2}/sec, where (film thickness){sup 2} = k{prime} x time. This activation energy is in agreement with results obtained by other techniques. A ...