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Sample records for hard hfb2 thin

  1. Thin coatings and films hardness evaluation

    NASA Astrophysics Data System (ADS)

    Matyunin, V. M.; Marchenkov, A. Yu; Demidov, A. N.; Karimbekov, M. A.

    2016-10-01

    The existing thin coatings and films hardness evaluation methods based on indentation with pyramidal indenter on various scale levels are expounded. The impact of scale factor on hardness values is performed. The experimental verification of several existing hardness evaluation methods regarding the substrate hardness value and the “coating - substrate” composite hardness value is made.

  2. A Two Phase HfB2-SiB4 Material

    NASA Technical Reports Server (NTRS)

    Wuchina, Eric J. (Inventor)

    1996-01-01

    A two phase HfB2-SiB4 material which is useful as a high temperature oxidation resistant coating. This invention relates to ceramic coatings and more particularly to ceramic coatings containing metal borides. Boride materials are known to have good oxidation resistance, with HfB2 considered to be the best pure boride for oxidation applications. It has been shown that the addition of 10 to 20 percent SiC to HfB2 increases the oxidation resistance. The HfB2-SiC materials are prepared by hot pressing powder mixtures. Hot pressing powder mixtures has limited ability to produce fine grained multiphase materials due to particle coarsening during the sintering process. Additionally, the purity of the final monolithic structure is limited to the purity of the starting powders. Chemical vapor deposition (CVD) offers a method of producing highly pure multiphase ceramics, with better control of microstructure. Researchers have tried to produce HfB2-SiC coatings by CVD but without success.

  3. Analysis of Hard Thin Film Coating

    NASA Technical Reports Server (NTRS)

    Shen, Dashen

    1998-01-01

    MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

  4. Analysis of Hard Thin Film Coating

    NASA Technical Reports Server (NTRS)

    Shen, Dashen

    1998-01-01

    Marshall Space Flight Center (MSFC) is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD) to deposit hard thin film on stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

  5. Lattice Thermal Conductivity from Atomistic Simulations: ZrB2 and HfB2

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  6. Ab initio Computations of the Electronic, Mechanical, and Thermal Properties of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Bauschlicher, Charles W.; Daw, Murray

    2011-01-01

    Refractory materials such as metallic borides, often considered as ultra high temperature ceramics (UHTC), are characterized by high melting point, high hardness, and good chemical inertness. These materials have many applications which require high temperature materials that can operate with no or limited oxidation. Ab initio, first principles methods are the most accurate modeling approaches available and represent a parameter free description of the material based on the quantum mechanical equations. Using these methods, many of the intrinsic properties of these material can be obtained. We performed ab initio calculations based on density functional theory for the UHTC materials ZrB2 and HfB2. Computational results are presented for structural information (lattice constants, bond lengths, etc), electronic structure (bonding motifs, densities of states, band structure, etc), thermal quantities (phonon spectra, phonon densities of states, specific heat), as well as information about point defects such as vacancy and antisite formation energies.

  7. Mechanical properties of ZrB2- and HfB2-based ultra-high temperature ceramics fabricated by spark plasma sintering

    SciTech Connect

    Zapata-Solvas, E.; Jayaseelan, D.; Lin, Hua-Tay; Brown, P.; Lee, W.E.

    2013-01-01

    Flexural strengths at room temperature, at 1400 C in air and at room temperature after 1 h oxidation at 1400 C were determined for ZrB2- and HfB2-based ultra-high temperature ceramics (UHTCs). Defects caused by electrical discharge machining (EDM) lowered measured strengths significantly and were used to calculate fracture toughness via a fracture mechanics approach. ZrB2 with 20 vol.% SiC had room temperature strength of 700 90 MPa, fracture toughness of 6.4 0.6 MPa, Vickers hardness at 9.8 N load of 21.1 0.6 GPa, 1400 C strength of 400 30 MPa and room temperature strength after 1 h oxidation at 1400 C of 678 15 MPa with an oxide layer thickness of 45 5 m. HfB2 with 20 vol.% SiC showed room temperature strength of 620 50 MPa, fracture toughness of 5.0 0.4 MPa, Vickers hardness at 9.8 N load of 27.0 0.6 GPa, 1400 C strength of 590 150 MPa and room temperature strength after 1 h oxidation at 1400 C of 660 25 MPa with an oxide layer thickness of 12 1 m. 2 wt.% La2O3 addition to UHTCs slightly reduced mechanical performance while increasing tolerance to property degradation after oxidation and effectively aided internal stress relaxation during spark plasma sintering (SPS) cooling, as quantified by X-ray diffraction (XRD). Slow crack growth was suggested as the failure mechanism at high temperatures as a consequence of sharp cracks formation during oxidation.

  8. Doping-induced superconductivity of ZrB2 and HfB2

    NASA Astrophysics Data System (ADS)

    Barbero, N.; Shiroka, T.; Delley, B.; Grant, T.; Machado, A. Â. J. Â. S.; Fisk, Z.; Ott, H.-R.; Mesot, J.

    2017-03-01

    Unlike the widely studied s -type two-gap superconductor MgB2, the chemically similar compounds ZrB2 and HfB2 do not superconduct above 1 K. Yet it has been shown that small amounts of self or extrinsic doping (in particular with vanadium), can induce superconductivity in these materials. Based on results of different macroscopic and microscopic measurements, including magnetometry, nuclear magnetic resonance (NMR), resistivity, and muon-spin rotation (μ+SR ), we present a comparative study of Zr0.96V0.04B2 and Hf0.97V0.03B2 . Their key magnetic and superconducting features are determined and the results are considered within the theoretical framework of multiband superconductivity proposed for MgB2. Detailed Fermi surface (FS) and electronic structure calculations reveal the difference between MgB2 and transition-metal diborides.

  9. Lattice Thermal Conductivity of Ultra High Temperature Ceramics ZrB2 and HfB2 from Atomistic Simulations

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Murray, Daw S.; Bauschlicher, Charles W., Jr.

    2011-01-01

    Atomistic Green-Kubo simulations are performed to evaluate the lattice thermal conductivity for single crystals of the ultra high temperature ceramics ZrB2 and HfB2 for a range of temperatures. Recently developed interatomic potentials are used for these simulations. Heat current correlation functions show rapid oscillations which can be identified with mixed metal-Boron optical phonon modes. Agreement with available experimental data is good.

  10. Thermal Conductivity Designed Hard Protective Thin Films

    DTIC Science & Technology

    2014-05-01

    University of Leoben. After his PhD in 2001 on Materials Science Aspects of Nanocrystalline PVD Hard Coatings in collaboration with the West Bohemian...Vienna University of Technology) Materials Science and Technology Karlsplatz 13 Wien (Vienna) 1040, AUSTRIA EOARD Grant 13-2147 Report Date: May...University of Technology) Materials Science and Technology Karlsplatz 13 Wien (Vienna) 1040, AUSTRIA 8. PERFORMING ORGANIZATION REPORT NUMBER N/A 9

  11. Lattice Thermal Conductivity of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2 from Atomistic Simulations

    NASA Technical Reports Server (NTRS)

    Lawson, JOhn W.; Daw, Murray S.; Bauschlicher, Charles W.

    2011-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 are candidate materials for applications in extreme environments because of their high melting point, good mechanical properties and reasonable oxidation resistance. Unlike many ceramics, these materials have high thermal conductivity which can be advantageous, for example, to reduce thermal shock. Recently, we developed Tersoff style interatomic potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current. Results at room temperature and at elevated temperatures will be reported.

  12. Taguchi Analysis on the Effect of Process Parameters on Densification During Spark Plasma Sintering of HfB2-20SiC (Preprint)

    DTIC Science & Technology

    2011-11-01

    AFRL-RX-WP-TP-2011-4397 TAGUCHI ANALYSIS ON THE EFFECT OF PROCESS PARAMATERS ON DENSIFICATION DURING SPARK PLASMA SINTERING OF HfB2-20SiC...of various process variables on the densification during spark plasma sintering of HfB2-20SiC was studied using Taguchi analysis. The statistical...achieved on sintering at 2100°C for 8 minutes at 30 kN pressure and heating rate of 100 K/min. 15. SUBJECT TERMS taguchi analysis; spark plasma

  13. Fractographic Analysis of HfB2-SiC and ZrB2-SiC Composites

    NASA Technical Reports Server (NTRS)

    Mecholsky, J.J., Jr.; Ellerby, D. T.; Johnson, S. M.; Stackpoole, M. M.; Loehman, R. E.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Hafnium diboride-silicon carbide and zirconium diboride-silicon carbide composites are potential materials for high temperature leading edge applications on reusable launch vehicles. In order to establish material constants necessary for evaluation of in-situ fracture, bars fractured in four point flexure were examined using fractographic principles. The fracture toughness was determined from measurements of the critical crack sizes and the strength values, and the crack branching constants were established to use in forensic fractography of materials for future flight applications. The fracture toughnesses range from about 13 MPam (sup 1/2) at room temperature to about 6 MPam (sup 1/2) at 1400 C for ZrB2-SiC composites and from about 11 MPam (sup 1/2) at room temperature to about 4 MPam (sup 1/2) at 1400 C for HfB2-SiC composites.

  14. Thin membranes of new hard/soft segment copolymers

    SciTech Connect

    Ho, W.S.; Sartori, G.; Thaler, W.A.

    1996-12-31

    Thin membranes of new hard/soft segment copolymers have been synthesized for the separation of aromatics from saturates through high temperature pervaporation. In the membranes, hard segments provide temperature stability and solvent resistance, while soft segments govern aromatic/saturate selectivity and flux. We have synthesized new chlorinated polyurethane/polyester and polyimide/polyester copolymers. Based on a polyimide copolymer membrane, a new technology has been developed recently to separate heavy catalytically cracked naphtha into an aromatics-rich permeate and an aromatics-lean retentate.

  15. Oxidation of ZrB2-and HfB2-Based Ultra-High Temperature Ceramics: Effects of Ta Additions

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth; Levine, Stanley; Lorinez, Jonathan

    2003-01-01

    Several compositions of ZrB2- and HfB2-based Ultra-High Temperature Ceramics (UHTC) were oxidized in stagnant air at 1627 C in ten minute cycles for times up to 100 minutes. These compositions include: ZrB2 - 20v% SiC, HfB2 - 20v% SiC, ZrB2 - 20v% SiC - 20v% TaSi2, ZrB2 - 33v% SiC, HfB2 - 20v% SiC - 20v% TaSi2, and ZrB2 - 20v% SiC - 20v% TaC. The weight change due to oxidation was recorded. The ZrB2 - 20v% SiC - 20v% TaSi2 composition was also oxidized in stagnant air at 1927 C and in an arc jet atmosphere. Samples were analyzed after oxidation by x-ray diffraction, field emission scanning electron microscopy, and energy dispersive spectroscopy to determine the reaction products and to observe the microstructure. The ZrB2 - 20v% SiC - 20v% TaSi2 showed the lowest oxidation rate at 1627 C, but performed poorly under the more extreme tests due to liquid phase formation. Effects of Ta-additions on the oxidation of the diboride-based UHTC are discussed.

  16. Lattice Thermal Conductivity of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2 from Atomistic Simulations

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  17. ZrB2-HfB2 solid solutions as electrode materials for hydrogen reaction in acidic and basic solutions

    DOE PAGES

    Sitler, Steven J.; Raja, Krishnan S.; Charit, Indrajit

    2016-11-09

    Spark plasma sintered transition metal diborides such as HfB2, ZrB2 and their solid solutions were investigated as electrode materials for electrochemical hydrogen evolutions reactions (HER) in 1 M H2SO4 and 1 M NaOH electrolytes. HfB2 and ZrB2 formed complete solid solutions when mixed in 1:1, 1:4, and 4:1 ratios and they were stable in both electrolytes. The HER kinetics of the diborides were slower in the basic solution than in the acidic solutions. The Tafel slopes in 1 M H2SO4 were in the range of 0.15 - 0.18 V/decade except for pure HfB2 which showed a Tafel slope of 0.38more » V/decade. In 1 M NaOH the Tafel slopes were in the range of 0.12 - 0.27 V/decade. The composition of HfxZr1-xB2 solid solutions with x = 0.2 - 0.8, influenced the exchange current densities, overpotentials and Tafel slopes of the HER. As a result, the EIS data were fitted with a porous film equivalent circuit model in order to better understand the HER behavior. In addition, modeling calculations, using density functional theory approach, were carried out to estimate the density of states and band structure of the boride solid solutions.« less

  18. Separating Test Artifacts from Material Behavior in the Oxidation Studies of HfB2-SiC at 2000 degs C and Above (Preprint)

    DTIC Science & Technology

    2011-11-01

    vol% SiC (HS). The powder mixtures were ball milled in isopropanol for 24 h with SiC grinding media, dried at room temperature, and subsequently dry...calculated eutectic at 2347°C in the HfB2-SiC system [15]. The oxide scale (inset Fig. 6) is composed of HfO2 penetrated by SiO2. Meng et. al. [12... eutectic temperature [15]), but did not show any micrographs of the interior microstructure. 4. Discussion The direct comparison of the zirconia

  19. Separating Test Artifacts from Material Behavior in the Oxidation Studies of HfB2 SiC at 2000 deg C and Above (POSTPRINT)

    DTIC Science & Technology

    2012-02-01

    The powder mixtures were ball milled in isopropanol for 24 h with SiC grinding media, dried at room tem- perature, and subsequently dry milled for 12...was confirmed by EDS to be SiC and HfB2. The microstructure suggests formation of a liquid phase, which is consistent with the calcu- lated eutectic ...failure of a ZrB2–SiC sample at temperatures above 2300°C (2207°C eutectic temperature16), but did not show any micrographs of the interior microstructure

  20. Buckle Driven Delamination in Thin Hard Film Compliant Substrate Systems

    NASA Astrophysics Data System (ADS)

    Moody, N. R.; Reedy, E. D.; Corona, E.; Adams, D. P.; Kennedy, M. S.; Cordill, M. J.; Bahr, D. F.

    2010-06-01

    Deformation and fracture of thin films on compliant substrates are key factors constraining the performance of emerging flexible substrate devices. [1-3] These systems often contain layers of thin polymer, ceramic and metallic films and stretchable interconnects where differing properties induce high normal and shear stresses. [4] As long as the films remain bonded to the substrates, they may deform far beyond their freestanding form. Once debonded, substrate constraint disappears leading to film failure. [3] Experimentally it is very difficult to measure properties in these systems at sub-micron and nanoscales. Theoretically it is very difficult to determine the contributions from the films, interfaces, and substrates. As a result our understanding of deformation and fracture behavior in compliant substrate systems is limited. This motivated a study of buckle driven delamination of thin hard tungsten films on pure PMMA substrates. The films were sputter deposited to thicknesses of 100 nm, 200 nm, and 400 nm with a residual compressive stress of 1.7 GPa. An aluminum oxide interlayer was added on several samples to alter interfacial composition. Buckles formed spontaneously on the PMMA substrates following film deposition. On films without the aluminum oxide interlayer, an extensive network of small telephone cord buckles formed following deposition, interspersed with regions of larger telephone cord buckles. (Figure 1) On films with an aluminum oxide interlayer, telephone cord buckles formed creating a uniform widely spaced pattern. Through-substrate optical observations revealed matching buckle patterns along the film-substrate interface indicating that delamination occurred for large and small buckles with and without an interlayer. The coexistence of large and small buckles on the same substrate led to two distinct behaviors as shown in Figure 2 where normalized buckle heights are plotted against normalized film stress. The behaviors deviate significantly from

  1. Nanotribological properties of nanostructured hard carbon thin films

    NASA Astrophysics Data System (ADS)

    Grierson, David S.

    Hard carbon thin films are important candidate materials to improve the tribological performance of mechanical components ranging from the macro- to the nanoscale. Extensive study at the macroscale has established their excellent tribomechanical properties, but little is known about their nanoscale properties. We investigated three carbon-based films: ultrananocrystalline diamond (UNCD), tetrahedral amorphous carbon (ta-C), and diamond-like carbon (DLC). We used near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to determine the chemical composition and the nature of the surface bonds. We used atomic force microscopy (AFM) to measure the work of adhesion and frictional forces between diamond tips (microcrystalline and UNCD) and both UNCD and ta-C surfaces, and between fluorinated DLC (F-DLC) tips and both F-DLC and silicon-containing DLC (Si-DLC). For UNCD, we were able to reach van der Waals's limit of adhesion for hydrocarbons (˜30 mJ/m2) and reduce nanoscale friction forces by terminating defective surfaces with hydrogen. This is particularly important for the underside of UNCD films, which we studied by etching away their underlying substrates. We found that this underside had a higher percentage of sp2 bonding and oxygen than the upper surface, but exposure to hydrogen plasma restored the sp3 character and improved the nanotribological properties. We studied ta-C films annealed from 200°C - 1000°C, and found that thermal annealing increased the sp2 bonding percentage. Above 600°C, the conversion from sp3→sp2 bonding increased dramatically. When the as-deposited films were oxygen-free, we observed no change in the work of adhesion (which is low at ˜40 mJ/m 2) as a function of thermal annealing, but we did see a reduction in nano scale friction. F-DLC and Si-DLC films were investigated before and after thermally annealing them at 300°C in air. The NEXAFS and AFM results demonstrated that Si-DLC is stable, both chemically and

  2. Multiscale Modeling of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2: Application to Lattice Thermal Conductivity

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Daw, Murray S.; Squire, Thomas H.; Bauschlicher, Charles W.

    2012-01-01

    We are developing a multiscale framework in computational modeling for the ultra high temperature ceramics (UHTC) ZrB2 and HfB2. These materials are characterized by high melting point, good strength, and reasonable oxidation resistance. They are candidate materials for a number of applications in extreme environments including sharp leading edges of hypersonic aircraft. In particular, we used a combination of ab initio methods, atomistic simulations and continuum computations to obtain insights into fundamental properties of these materials. Ab initio methods were used to compute basic structural, mechanical and thermal properties. From these results, a database was constructed to fit a Tersoff style interatomic potential suitable for atomistic simulations. These potentials were used to evaluate the lattice thermal conductivity of single crystals and the thermal resistance of simple grain boundaries. Finite element method (FEM) computations using atomistic results as inputs were performed with meshes constructed on SEM images thereby modeling the realistic microstructure. These continuum computations showed the reduction in thermal conductivity due to the grain boundary network.

  3. Oxidation Resistance, Electrical and Thermal Conductivity, and Spectral Emittance of Fully Dense HfB2 and ZrB2 with SiC, TaSi2, and LaB6 Additives

    DTIC Science & Technology

    2012-01-26

    Bouchacourt [19]. h. Spark - plasma sinterered B4C (not isotopically enriched), 98% relative density [21]. i. EP (Eagle-Pitcher) hot-pressed B4C [22]. j...silicate surface coating observed to form. Carney [4] investigated the oxidation behavior of HfB2 - 20 vol% SiC (fabricated through 57 spark plasma ...C. The thermal diffusivities oftheoretically dense ZrB2-SiC (10. 7, 21.9, or 48.7 vol% SiC) sintered /HIPed "With B4C sintering aid was measured using

  4. Thermally evaporated mechanically hard tin oxide thin films for opto-electronic apllications

    NASA Astrophysics Data System (ADS)

    Tripathy, Sumanta K.; Rajeswari, V. P.

    2014-01-01

    Tungsten doped tin oxide (WTO) and Molybdenum doped tin oxide (MoTO) thin film were deposited on corn glass by thermal evaporation method. The films were annealed at 350°C for one hour. Structural analysis using Xray diffraction data shows both the films are polycrystalline in nature with monoclinic structure of tin oxide, Sn3O4, corresponding to JCPDS card number 01-078-6064. SEM photograph showed that both the films have spherical grains with size in the range of 20-30 nm. Compositional analysis was carried out using EDS which reveals the presence of Sn, O and the dopant Mo/W only thereby indicating the absence of any secondary phase in the films. The films are found to contain nearly 6 wt% of Mo, 8 wt% of W as dopants respectively. The transmission pattern for both the films in the spectral range 200 - 2000 nm shows that W doping gives a transparency of nearly 80% from 380 nm onwards while Mo doping has less transparency of 39% at 380nm. Film hardness measurement using Triboscope shows a film hardness of about 9-10 GPa for both the films. It indicates that W or M doping in tin oxide provides the films the added advantage of withstanding the mechanical wear and tear due to environmental fluctuations By optimizing the optical and electrical properties, W/Mo doped tin oxide films may be explored as window layers in opto-electronic applications such as solar cells.

  5. Thermally evaporated mechanically hard tin oxide thin films for opto-electronic apllications

    SciTech Connect

    Tripathy, Sumanta K.; Rajeswari, V. P.

    2014-01-28

    Tungsten doped tin oxide (WTO) and Molybdenum doped tin oxide (MoTO) thin film were deposited on corn glass by thermal evaporation method. The films were annealed at 350°C for one hour. Structural analysis using Xray diffraction data shows both the films are polycrystalline in nature with monoclinic structure of tin oxide, Sn{sub 3}O{sub 4}, corresponding to JCPDS card number 01-078-6064. SEM photograph showed that both the films have spherical grains with size in the range of 20–30 nm. Compositional analysis was carried out using EDS which reveals the presence of Sn, O and the dopant Mo/W only thereby indicating the absence of any secondary phase in the films. The films are found to contain nearly 6 wt% of Mo, 8 wt% of W as dopants respectively. The transmission pattern for both the films in the spectral range 200 – 2000 nm shows that W doping gives a transparency of nearly 80% from 380 nm onwards while Mo doping has less transparency of 39% at 380nm. Film hardness measurement using Triboscope shows a film hardness of about 9–10 GPa for both the films. It indicates that W or M doping in tin oxide provides the films the added advantage of withstanding the mechanical wear and tear due to environmental fluctuations By optimizing the optical and electrical properties, W/Mo doped tin oxide films may be explored as window layers in opto-electronic applications such as solar cells.

  6. Transition Metal Diborides as Electrode Material for MHD Direct Power Extraction: High-temperature Oxidation of ZrB2-HfB2 Solid Solution with LaB6 Addition

    NASA Astrophysics Data System (ADS)

    Sitler, Steven; Hill, Cody; Raja, Krishnan S.; Charit, Indrajit

    2016-06-01

    Transition metal borides are being considered for use as potential electrode coating materials in magnetohydrodynamic direct power extraction plants from coal-fired plasma. These electrode materials will be exposed to aggressive service conditions at high temperatures. Therefore, high-temperature oxidation resistance is an important property. Consolidated samples containing an equimolar solid solution of ZrB2-HfB2 with and without the addition of 1.8 mol pct LaB6 were prepared by ball milling of commercial boride material followed by spark plasma sintering. These samples were oxidized at 1773 K (1500 °C) in two different conditions: (1) as-sintered and (2) anodized (10 V in 0.1 M KOH electrolyte). Oxidation studies were carried out in 0.3 × 105 and 0.1 Pa oxygen partial pressures. The anodic oxide layers showed hafnium enrichment on the surface of the samples, whereas the high-temperature oxides showed zirconium enrichment. The anodized samples without LaB6 addition showed about 2.5 times higher oxidation resistance in high-oxygen partial pressures than the as-sintered samples. Addition of LaB6 improved the oxidation resistance in the as-sintered condition by about 30 pct in the high-oxygen partial pressure tests.

  7. Hard templating of symmetric and asymmetric carbon thin films with three-dimensionally ordered mesoporosity.

    PubMed

    Tian, Zheng; Snyder, Mark A

    2014-08-19

    Sacrificial colloidal crystal templating of porous carbon films of tunable thickness is demonstrated using a facile thin-film assembly and hard-template-based nanoreplication process. Convectively assembled, colloidal crystal films composed of size-tunable silica nanoparticles (ca. 10-50 nm) serve as scalable sacrificial scaffolds for the formation of thickness-tunable, structurally robust, and flexible porous carbon films. Both precursor vapor infiltration (PVI) and precursor immersion/spin-off (PIS) techniques, suitable for replication by various carbon sources (e.g., furfural/oxalic acid, phenol-formaldehyde, resorcinol-formaldehyde, sucrose), result in continuous, crack-free porous replica films. Systematic PVI-based underfilling of the template film or PIS-based complete spin-off of excess carbon replica precursor results in porous carbon films endowed with a symmetric three-dimensionally ordered mesopore (3DOm) topology uniformly distributed across the film thickness. Alternatively, by tuning the nanoparticle crystal film thickness and the degree of overfilling (PVI) or rate of spin-off of the carbon replica precursor (PIS), films bearing an asymmetric structure composed of 3DOm-supported ultrathin carbon layers can be realized. The stability of the silica templates under polymerization and carbonization conditions helps bolster mesopore robustness within the replica films, eliminating uniaxial pore shrinkage upon template sacrifice. The decoupling of the template assembly and its replication enables film formation from a wide range of carbon sources and possibly a further expanded materials palette. Realization of porous carbon films on various substrates without degradation of the mesostructure is enabled by robustness of the coating/replication process to characteristic surface roughness at scales several-fold larger than the template particle size as well as to polymer-mediated film transfer. Among various possible applications, we demonstrate how

  8. Thin-film-based scintillators for hard x-ray microimaging detectors: the ScinTAX Project

    NASA Astrophysics Data System (ADS)

    Rack, A.; Cecilia, A.; Douissard, P.-A.; Dupré, K.; Wesemann, V.; Baumbach, T.; Couchaud, M.; Rochet, X.; Riesemeier, H.; Radtke, M.; Martin, T.

    2014-09-01

    The project ScinTAX developed novel thin scintillating films for the application in high performance X-ray imaging and subsequent introduced new X-ray detectors to the market. To achieve this aim lutetium orthosilicate (LSO) scintillators doped with different activators were grown successfully by liquid phase epitaxy. The high density of LSO (7.4 g/cm3), the effective atomic number (65.2) and the high light yield make this scintillator highly applicable for indirect X-ray detection in which the ionizing radiation is converted into visible light and then registered by a digital detector. A modular indirect detection system has been developed to fully exploit the potential of this thin film scintillator for radiographic and tomographic imaging. The system is compatible for high-resolution imaging with moderate dose as well as adaptable to intense high-dose applications where radiation hard microimaging detectors are required. This proceedings article shall review the achieved performances and technical details on this high-resolution detector system which is now available. A selected example application demonstrates the great potential of the optimized detector system for hard X-ray microimaging, i.e. either to improve image contrast due to the availability of efficient thin crystal films or to reduce the dose to the sample.

  9. Nanoscale morphology for high hydrophobicity of a hard sol gel thin film

    NASA Astrophysics Data System (ADS)

    Wu, Y. L.; Chen, Z.; Zeng, X. T.

    2008-08-01

    It is challenging to obtain a hydrophobic smooth coating with high optical and mechanical properties at the same time because the hydrophobic additives are soft in nature resulting in reduced hardness and durability. This paper reports a durable hydrophobic transparent coating on glass fabricated by sol-gel technology and a low volume medium pressure (LVMP) spray process. The sol-gel formula consists of a pre-linked hydrophobic nano-cluster from hydroxyl-terminated polydimethylsiloxane, titanium tetraisopropoxide and a silica-based sol-gel matrix with silica hard fillers. Polydimethylsiloxane (PDMS) is uniformly distributed throughout the coating layer providing durable hydrophobic property. Mechanical properties are achieved by the hard matrix and hard fillers with the nano-structures. Due to the surface nano-morphology, a high degree of hydrophobicity was maintained with only 10 vol.% PDMS, while the hardness and abrasion resistance of the coatings were not significantly compromised. Chemical analyses by FTIR confirmed the uniform distribution of the PDMS and surface morphology analyses by atomic force microscopy (AFM) displayed the nano-surface structures that enhanced the hydrophobicity. The special surface nanostructures can be quantified using surface Kurtosis and ratio between asperity peak height to distance between peaks. The LVMP process influences the spray droplet size resulting in different surface structures.

  10. Densification of sol-gel silica thin films induced by hard X-rays generated by synchrotron radiation.

    PubMed

    Innocenzi, Plinio; Malfatti, Luca; Kidchob, Tongjit; Costacurta, Stefano; Falcaro, Paolo; Marmiroli, Benedetta; Cacho-Nerin, Fernando; Amenitsch, Heinz

    2011-03-01

    In this article the effects induced by exposure of sol-gel thin films to hard X-rays have been studied. Thin films of silica and hybrid organic-inorganic silica have been prepared via dip-coating and the materials were exposed immediately after preparation to an intense source of light of several keV generated by a synchrotron source. The samples were exposed to increasing doses and the effects of the radiation have been evaluated by Fourier transform infrared spectroscopy, spectroscopic ellipsometry and atomic force microscopy. The X-ray beam induces a significant densification on the silica films without producing any degradation such as cracks, flaws or delamination at the interface. The densification is accompanied by a decrease in thickness and an increase in refractive index both in the pure silica and in the hybrid films. The effect on the hybrid material is to induce densification through reaction of silanol groups but also removal of the organic groups, which are covalently bonded to silicon via Si-C bonds. At the highest exposure dose the removal of the organic groups is complete and the film becomes pure silica. Hard X-rays can be used as an efficient and direct writing tool to pattern coating layers of different types of compositions.

  11. Supernormal hardness increase of dilute Ga(As, N) thin films

    NASA Astrophysics Data System (ADS)

    Berggren, Jonas; Hanke, Michael; Luna, Esperanza; Trampert, Achim

    2017-03-01

    Hardness of epitaxial GaAs1-xNx films on GaAs(001) with different film thicknesses, varying from 80 to 700 nm, and nitrogen compositions x between zero (pure GaAs) and 0.031, were studied by means of nano-indentation. As a result, a disproportionate and monotonic increase by 17% in hardness was proved in the dilute range from GaAs to GaAs0.969N0.031. We are tracing this observation to solid solution strengthening, an extrinsic effect based on dislocation pinning due to interstitial nitrogen. On the other hand, intrinsic effects related to different electronegativities of As and N (i.e., altered bonding conditions) could be ruled out. Furthermore, in tensilely strained GaAs1-xNx layers, the appearance of cracks acts as the main strain relieving mechanism. A correlation between cracking and hardness reduction is investigated and discussed as a further relaxation pathway.

  12. Apparatus and Method for Cold Welding Thin Wafers to Hard Substrates

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C. (Inventor); Smith, Floyd A. (Inventor)

    1996-01-01

    An apparatus for coating and bonding parts in a vacuum includes a floating mount assembly holding one part and applying a bonding load to the parts. A pivoting mount assembly holds one part and is pivoted between a coating position and a bonding position. At least one coating source is provided for depositing a thin film of a metal onto a surface of each of the parts to improve the cold weld between the two parts. A restraining lever controls the application of the bonding load to the parts. The coating and bonding process occurs in a vacuum chamber with a single set-up.

  13. a Numerical Method for Scattering from Acoustically Soft and Hard Thin Bodies in Two Dimensions

    NASA Astrophysics Data System (ADS)

    YANG, S. A.

    2002-03-01

    This paper presents a numerical method for predicting the acoustic scattering from two-dimensional (2-D) thin bodies. Both the Dirichlet and Neumann problems are considered. Applying the thin-body formulation leads to the boundary integral equations involving weakly singular and hypersingular kernels. Completely regularizing these kinds of singular kernels is thus the main concern of this paper. The basic subtraction-addition technique is adopted. The purpose of incorporating a parametric representation of the boundary surface with the integral equations is two-fold. The first is to facilitate the numerical implementation for arbitrarily shaped bodies. The second one is to facilitate the expansion of the unknown function into a series of Chebyshev polynomials. Some of the resultant integrals are evaluated by using the Gauss-Chebyshev integration rules after moving the series coefficients to the outside of the integral sign; others are evaluated exactly, including the modified hypersingular integral. The numerical implementation basically includes only two parts, one for evaluating the ordinary integrals and the other for solving a system of algebraic equations. Thus, the current method is highly efficient and accurate because these two solution procedures are easy and straightforward. Numerical calculations consist of the acoustic scattering by flat and curved plates. Comparisons with analytical solutions for flat plates are made.

  14. Reactive magnetron cosputtering of hard and conductive ternary nitride thin films: Ti-Zr-N and Ti-Ta-N

    SciTech Connect

    Abadias, G.; Koutsokeras, L. E.; Dub, S. N.; Tolmachova, G. N.; Debelle, A.; Sauvage, T.; Villechaise, P.

    2010-07-15

    Ternary transition metal nitride thin films, with thickness up to 300 nm, were deposited by dc reactive magnetron cosputtering in Ar-N{sub 2} plasma discharges at 300 deg. C on Si substrates. Two systems were comparatively studied, Ti-Zr-N and Ti-Ta-N, as representative of isostructural and nonisostructural prototypes, with the aim of characterizing their structural, mechanical, and electrical properties. While phase-separated TiN-ZrN and TiN-TaN are the bulk equilibrium states, Ti{sub 1-x}Zr{sub x}N and Ti{sub 1-y}Ta{sub y}N solid solutions with the Na-Cl (B1-type) structure could be stabilized in a large compositional range (up to x=1 and y=0.75, respectively). Substituting Ti atoms by either Zr or Ta atoms led to significant changes in film texture, microstructure, grain size, and surface morphology, as evidenced by x-ray diffraction, x-ray reflectivity, and scanning electron and atomic force microscopies. The ternary Ti{sub 1-y}Ta{sub y}N films exhibited superior mechanical properties to Ti{sub 1-x}Zr{sub x}N films as well as binary compounds, with hardness as high as 42 GPa for y=0.69. All films were metallic, the lowest electrical resistivity {rho}{approx}65 {mu}{Omega} cm being obtained for pure ZrN, while for Ti{sub 1-y}Ta{sub y}N films a minimum was observed at y{approx}0.3. The evolution of the different film properties is discussed based on microstructrural investigations.

  15. Temperature of Heating and Cooling of Massive, Thin, and Wedge-Shaped Plates from Hard-to-Machine Steels During Their Grinding

    NASA Astrophysics Data System (ADS)

    Dement‧ev, V. B.; Ivanova, T. N.; Dolginov, A. M.

    2017-01-01

    Grinding of flat parts occurs by solid abrasive particles due to the physicomechanical process of deformation and to the action of a process liquid at high temperatures in a zone small in volume and difficult for observation. The rate of heating and cooling depends on the change in the intensity of the heat flux and in the velocity and time of action of the heat source. A study has been made of the regularities of the influence of each of these parameters on the depth and character of structural transformations during the grinding of flat parts from hard-to-machine steels. A procedure to calculate temperature in grinding massive, thin, and wedge-shaped parts has been developed with account taken of the geometric and thermophysical parameters of the tool and the treated part, and also of cutting regimes. The procedure can be used as a constituent part in developing a system for automatic design of the technological process of grinding of flat surfaces. A relationship between the temperature in the grinding zone and the regimes of treatment has been established which makes it possible to control the quality of the surface layer of massive, thin, and wedge-shaped plates from hard-to-machine steels. The rational boundaries of shift of cutting regimes have been determined.

  16. Relation between electrical properties of aerosol-deposited BaTiO3 thin films and their mechanical hardness measured by nano-indentation

    PubMed Central

    2012-01-01

    To achieve a high capacitance density for embedded decoupling capacitor applications, the aerosol deposition (AD) process was applied as a thin film deposition process. BaTiO3 films were fabricated on Cu substrates by the AD process at room temperature, and the film thickness was reduced to confirm the limit of the critical minimum thickness for dielectric properties. As a result, the BaTiO3 thin films that were less than 1-μm thick showed unstable electric properties owing to their high leakage currents. Therefore, to overcome this problem, the causes of the high leakage currents were investigated. In this study, it was confirmed that by comparing BaTiO3 thin films on Cu substrates with those on stainless steels (SUS) substrates, macroscopic defects and rough interfaces between films and substrates influence the leakage currents. Moreover, based on the deposition mechanism of the AD process, it was considered that the BaTiO3 thin films on Cu substrates with thicknesses of less than 1 μm are formed with chinks and weak particle-to-particle bonding, giving rise to leakage currents. In order to confirm the relation between the above-mentioned surface morphologies and the dielectric behavior, the hardness of BaTiO3 films on Cu and SUS substrates was investigated by nano-indentation. Consequently, we proposed that the chinks and weak particle-to-particle bonding in the BaTiO3 thin films with thicknesses of less than 0.5 μm on Cu substrates could be the main cause of the high leakage currents. PMID:22616759

  17. On the radiation hardness of (Mg,Zn)O thin films grown by pulsed-laser deposition

    SciTech Connect

    Schmidt, Florian; Wenckstern, Holger von; Spemann, Daniel; Grundmann, Marius

    2012-07-02

    We report on electrical properties and the generation of the E4 defect in pulsed-laser deposited Mg{sub x}Zn{sub 1-x}O thin films irradiated with 2.25 MeV protons. Whereas the electrical properties of the Schottky diodes as well as the net doping density of the samples did not change due to irradiation, the concentration of the E4 defect increased proportional to the applied dose as revealed by deep level transient spectroscopy. The generation rate {eta}, is for binary ZnO thin films about 40 cm{sup -1}, a factor of 3 higher than in melt-grown single crystals, and increases to about 100 cm{sup -1} for the Mg-alloyed thin films.

  18. Optical Characterization of Pulse Laser Deposition of Thin Film of Hard Materials Using RHEED and AFM Techniques (DURIP)

    DTIC Science & Technology

    2011-09-26

    Ferrite (BaFeO3) have been fabricated by the pulsed laser deposition technique on a Si substrate. The magnetic parameters were measured using vibrating...presented. 1. INTRODUCTION Barium ferrite powder was selected in this study because of its suitable coercive force (HC) and large remnant...was studied in the case of six fine- powder samples of barium ferrite . Then the selected BaFeO3 materials were used to produce a doped PLD thin film

  19. Optical Characterization of Pulse Laser Deposition of Thin Films of Hard Materials Using RHEED and AFM Techniques

    DTIC Science & Technology

    2011-12-20

    University, New Orleans, LA 70122 ABSTRACT Epitaxial thin films of Barium Ferrite (BaFeO3) have been fabricated by the pulsed laser deposition...the Coercivity, crystalline orientation, and grain shape and size is presented. 1. INTRODUCTION Barium ferrite powder was selected in this...published. In the presently conducted investigation, FMR absorption was studied in the case of six fine- powder samples of barium ferrite

  20. Origin of resistivity change in NiO thin films studied by hard x-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Calka, P.; Martinez, E.; Lafond, D.; Minoret, S.; Tirano, S.; Detlefs, B.; Roy, J.; Zegenhagen, J.; Guedj, C.

    2011-06-01

    We investigated origins of the resistivity change during the forming of NiO based resistive random access memories in a nondestructive way using hard x-ray photoelectron spectroscopy. Energy shifts and bandgap states observed after switching suggest that oxygen vacancies are created in the low resistive state. As a result conduction may occur via defects such as electrons traps and metallic nickel impurities. Migration of oxygen atoms seems to be the driving mechanism. This provides concrete evidence of the major role played by oxygen defects in decreasing resistivity. This is a key point since oxygen vacancies are particularly unstable and thus difficult to identify by physico-chemical analyses.

  1. Role of nitrogen in the formation of hard and elastic CNx thin films by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hellgren, Niklas; Johansson, Mats P.; Broitman, Esteban; Hultman, Lars; Sundgren, Jan-Eric

    1999-02-01

    Carbon nitride films, deposited by reactive dc magnetron sputtering in Ar/N2 discharges, were studied with respect to composition, structure, and mechanical properties. CNx films, with 0<=x<=0.35, were grown onto Si (001) substrates at temperatures between 100 and 550 °C. The total pressure was kept constant at 3.0 mTorr with the N2 fraction varied from 0 to 1. As-deposited films were studied by Rutherford-backscattering spectroscopy, x-ray photoelectron spectroscopy, electron-energy loss spectroscopy, Raman and Fourier transform infrared spectroscopy, and nanoindentation. Three characteristic film structures could be identified: For temperatures below ~150 °C, an amorphous phase forms, the properties of which are essentially unaffected by the nitrogen concentration. For temperatures above ~200 °C, a transition from a graphitelike phase to a ``fullerenelike'' phase is observed when the nitrogen concentration increases from ~5 to ~15 at. %. This fullerenelike phase exhibits high hardness values and extreme elasticity, as measured by nanoindentation. A ``defected-graphite'' model, where nitrogen atoms goes into substitutional graphite sites, is suggested for explaining this structural transformation. When a sufficient number of nitrogen atoms is incorporated, formation of pentagons is promoted, leading to curving of the basal planes. This facilitates cross-linking between the planes and a distortion of the graphitic structure, and a strong three-dimensional covalently bonded network is formed.

  2. Digital radiology using active matrix readout of amorphous selenium: radiation hardness of cadmium selenide thin film transistors.

    PubMed

    Zhao, W; Waechter, D; Rowlands, J A

    1998-04-01

    A flat-panel x-ray imaging detector using active matrix readout of amorphous selenium (a-Se) is being investigated for digital radiography and fluoroscopy. The active matrix consists of a two-dimensional array of thin film transistors (TFTs). Radiation penetrating through the a-Se layer will interact with the TFTs and it is important to ensure that radiation induced changes will not affect the operation of the x-ray imaging detector. The methodology of the present work is to investigate the effects of radiation on the characteristic curves of the TFTs using individual TFT samples made with cadmium selenide (CdSe) semiconductor. Four characteristic parameters, i.e., threshold voltage, subthreshold swing, field effect mobility, and leakage current, were examined. This choice of parameters was based on the well established radiation damage mechanisms for crystalline silicon metal-oxide-semiconductor field-effect transistors (MOSFETs), which have a similar principle of operation as CdSe TFTs. It was found that radiation had no measurable effect on the leakage current and the field effect mobility. However, radiation shifted the threshold voltage and increased the subthreshold swing. But even the estimated lifetime dose (50 Gy) of a diagnostic radiation detector will not affect the normal operation of an active matrix x-ray detector made with CdSe TFTs. The mechanisms of the effects of radiation will be discussed and compared with those for MOSFETs and hydrogenated amorphous silicon (a-Si:H) TFTs.

  3. Crack suppression of silica glass formed by zoned F2 laser-induced photochemical surface modification of hard silicone thin film coating on polycarbonate

    NASA Astrophysics Data System (ADS)

    Nojiri, Hidetoshi; Okoshi, Masayuki

    2016-12-01

    The surface layer of a hard silicone thin film coating on polycarbonate was modified to silica glass (SiO2) through F2-laser-induced photochemical reactions. To obtain samples with higher abrasion resistances, SiO2 films of 1 µm thickness and over were successfully formed without cracking, by zoning the laser-irradiated area of micrometer order. With the conversion of silicone to SiO2, the volumetric shrinkage of the sample was induced, which simply depended on the number of photons, by varying the single-pulse fluence and irradiation time of a F2 laser. The ratio of volumetric shrinkage to the original silicone was estimated to be approximately 0.85, generating tensile stress in SiO2. The stress could be suppressed to be lower than 48 MPa for typical SiO2 by reducing the laser-irradiated area to be of micrometer order. Also, when the length of one side of the irradiated area is 1 mm, the thickness of the SiO2 film is expected to increase to approximately 5 µm.

  4. Hard X-ray photoelectron spectroscopy of LixNi1-xO epitaxial thin films with a high lithium content

    NASA Astrophysics Data System (ADS)

    Kumara, L. S. R.; Sakata, Osami; Yang, Anli; Yamauchi, Ryosuke; Taguchi, Munetaka; Matsuda, Akifumi; Yoshimoto, Mamoru

    2014-07-01

    The core-level and valence-band electronic structures of LixNi1-xO epitaxial thin films with x = 0, 0.27, and 0.48 were studied by hard X-ray photoelectron spectroscopy. A double peak structure, consisting of a main peak and a shoulder peak, and a satellite structure were observed in the Ni 2p3/2 core-level spectra. The intensity ratio of the shoulder to main peak in this double peak structure increased with increasing lithium content in LixNi1-xO. This lithium doping dependence of the Ni 2p3/2 core-level spectra was investigated using an extended cluster model, which included the Zhang-Rice (ZR) doublet bound states arising from a competition between O 2p - Ni 3d hybridization and the Ni on-site Coulomb interaction. The results indicated that the change in the intensity ratio in the main peak is because of a reduction in the ZR doublet bound states from lithium substitutions. This strongly suggests that holes compensating Li doping in LixNi1-xO are of primarily ZR character.

  5. Novel strategy for low-temperature, high-rate growth of dense, hard, and stress-free refractory ceramic thin films

    SciTech Connect

    Greczynski, Grzegorz Lu, Jun; Hultman, Lars; Bolz, Stephan; Kölker, Werner; Schiffers, Christoph; Lemmer, Oliver; Petrov, Ivan; Greene, Joseph E.

    2014-07-01

    Growth of fully dense refractory thin films by means of physical vapor deposition (PVD) requires elevated temperatures T{sub s} to ensure sufficient adatom mobilities. Films grown with no external heating are underdense, as demonstrated by the open voids visible in cross-sectional transmission electron microscopy images and by x-ray reflectivity results; thus, the layers exhibit low nanoindentation hardness and elastic modulus values. Ion bombardment of the growing film surface is often used to enhance densification; however, the required ion energies typically extract a steep price in the form of residual rare-gas-ion-induced compressive stress. Here, the authors propose a PVD strategy for the growth of dense, hard, and stress-free refractory thin films at low temperatures; that is, with no external heating. The authors use TiN as a model ceramic materials system and employ hybrid high-power pulsed and dc magnetron co-sputtering (HIPIMS and DCMS) in Ar/N{sub 2} mixtures to grow dilute Ti{sub 1−x}Ta{sub x}N alloys on Si(001) substrates. The Ta target driven by HIPIMS serves as a pulsed source of energetic Ta{sup +}/Ta{sup 2+} metal–ions, characterized by in-situ mass and energy spectroscopy, while the Ti target operates in DCMS mode (Ta-HIPIMS/Ti-DCMS) providing a continuous flux of metal atoms to sustain a high deposition rate. Substrate bias V{sub s} is applied in synchronous with the Ta-ion portion of each HIPIMS pulse in order to provide film densification by heavy-ion irradiation (m{sub Ta} = 180.95 amu versus m{sub Ti} = 47.88 amu) while minimizing Ar{sup +} bombardment and subsequent trapping in interstitial sites. Since Ta is a film constituent, primarily residing on cation sublattice sites, film stress remains low. Dense Ti{sub 0.92}Ta{sub 0.08}N alloy films, 1.8 μm thick, grown with T{sub s} ≤ 120 °C (due to plasma heating) and synchronized bias, V{sub s} = 160 V, exhibit nanoindentation hardness H = 25.9 GPa and

  6. Enhanced hardness in epitaxial TiAlScN alloy thin films and rocksalt TiN/(Al,Sc)N superlattices

    SciTech Connect

    Saha, Bivas; Lawrence, Samantha K.; Bahr, David F.; Schroeder, Jeremy L.; Birch, Jens; Sands, Timothy D.

    2014-10-13

    High hardness TiAlN alloys for wear-resistant coatings exhibit limited lifetimes at elevated temperatures due to a cubic-AlN to hexagonal-AlN phase transformation that leads to decreasing hardness. We enhance the hardness (up to 46 GPa) and maximum operating temperature (up to 1050 °C) of TiAlN-based coatings by alloying with scandium nitride to form both an epitaxial TiAlScN alloy film and epitaxial rocksalt TiN/(Al,Sc)N superlattices on MgO substrates. The superlattice hardness increases with decreasing period thickness, which is understood by the Orowan bowing mechanism of the confined layer slip model. These results make them worthy of additional research for industrial coating applications.

  7. Effects of electron recirculation on a hard x-ray source observed during the interaction of a high intensity laser pulse with thin Au targets

    SciTech Connect

    Compant La Fontaine, A.; Courtois, C.; Lefebvre, E.; Bourgade, J. L.; Landoas, O.; Thorp, K.; Stoeckl, C.

    2013-12-15

    The interaction of a high intensity laser pulse on the preplasma of a high-Z solid target produced by the pulse's pedestal generates high-energy electrons. These electrons subsequently penetrate inside the solid target and produce bremsstrahlung photons, generating an x-ray source which can be used for photonuclear studies or to radiograph high area density objects. The source characteristics are compared for targets with thin (20 μm) and thick (100 μm) Au foils on the Omega EP laser at Laboratory for Laser Energetics. Simulations using the particle-in-cell code CALDER show that for a 20 μm thickness Au target, electrons perform multiple round-trips in the target under the effect of the laser ponderomotive potential and the target electrostatic potential. These relativistic electrons have random transverse displacements, with respect to the target normal, attributed to electrostatic fluctuation fields. As a result, the x-ray spot size is increased by a factor 2 for thin target compared to thick targets, in agreement with experimental results. In addition, the computed doses agree with the measured ones provided that electron recirculation in the thin target is taken into account. A dose increase by a factor 1.7 is then computed by allowing for recirculation. In the 100 μm target case, on the other hand, this effect is found to be negligible.

  8. Magnetically Hard Fe3Se4 Embedded in Bi2Se3 Topological Insulator Thin Films Grown by Molecular Beam Epitaxy.

    PubMed

    Vasconcelos, Hugo Menezes do Nascimento; Eddrief, Mahmoud; Zheng, Yunlin; Demaille, Dominique; Hidki, Sarah; Fonda, Emiliano; Novikova, Anastasiia; Fujii, Jun; Torelli, Piero; Salles, Benjamin Rache; Vobornik, Ivana; Panaccione, Giancarlo; de Oliveira, Adilson Jesus Aparecido; Marangolo, Massimiliano; Vidal, Franck

    2016-01-26

    We investigated the structural, magnetic, and electronic properties of Bi2Se3 epilayers containing Fe grown on GaAs(111) by molecular beam epitaxy. It is shown that, in the window of growth parameters leading to Bi2Se3 epilayers with optimized quality, Fe atom clustering leads to the formation of FexSey inclusions. These objects have platelet shape and are embedded within Bi2Se3. Monoclinic Fe3Se4 is identified as the main secondary phase through detailed structural measurements. Due to the presence of the hard ferrimagnetic Fe3Se4 inclusions, the system exhibits a very large coercive field at low temperature and room temperature magnetic ordering. Despite this composite structure and the proximity of a magnetic phase, the surface electronic structure of Bi2Se3 is preserved, as shown by the persistence of a gapless Dirac cone at Γ.

  9. The hard magnetic properties and microstructure evolution of the multilayer [NdFeBNbCu/FeBSi]ṡn thin films

    NASA Astrophysics Data System (ADS)

    Chiriac, H.; Grigoras, M.; Lupu, N.; Urse, M.; Buta, V.

    2008-04-01

    The influence of the thickness of constituent layers and annealing conditions for multilayer [NdFeBNbCu/FeBSi]ṡn thin films on the magnetic properties and microstructure is reported. The Nb-Cu combination inhibits the grain growth and promotes the formation of nucleation sites. The FeSiB layer insertion leads to a slight increase in the Curie temperature and to a rectangular hysteresis loop. As compared to Ta /NdFeBNbCu (540nm)/Ta single layer, the Ta /[NdFeBNbCu(180nm)/FeBSi(15nm)]ṡ3/Ta multilayer nanocomposite films exhibit very good magnetic properties such as squareness Mr/Ms of about 0.92, maximum energy product of about 397kJ/m3, and an increase in the Curie temperature of about 17°C due to stratification by using FeBSi film as space layer.

  10. Suzaku Observations of Moderately Obscured (Compton-thin) Active Galactic Nuclei Selected by Swift/BAT Hard X-ray Survey

    NASA Astrophysics Data System (ADS)

    Kawamuro, Taiki; Ueda, Yoshihiro; Tazaki, Fumie; Ricci, Claudio; Terashima, Yuichi

    2016-07-01

    We report the results obtained by a systematic, broadband (0.5-150 keV) X-ray spectral analysis of moderately obscured (Compton-thin, 22≤slant {log}{N}{{H}}\\lt 24) active galactic nuclei (AGNs) observed with Suzaku and Swift/Burst Alert Telescope (BAT). Our sample consists of 45 local AGNs at z\\lt 0.1 with {log}{L}14-195{keV}\\gt 42 detected in the Swift/BAT 70-month survey, whose Suzaku archival data are available as of 2015 December. All spectra are uniformly fit with a baseline model composed of an absorbed cutoff power-law component, reflected emission accompanied by a narrow fluorescent iron-Kα line from cold matter (torus), and scattered emission. The main results based on the above analysis are as follows. (1) The photon index is correlated with Eddington ratio, but not with luminosity or black hole mass. (2) The ratio of the luminosity of the iron-Kα line to the X-ray luminosity an indicator of the covering fraction of the torus, shows significant anticorrelation with luminosity. (3) The averaged reflection strength derived from stacked spectra above 14 keV is larger in less luminous ({log}{L}10-50{keV}≤slant 43.3, R={1.04}-0.19+0.17) or highly obscured ({log}{N}{{H}}\\gt 23, R={1.03}-0.17+0.15) AGNs than in more luminous ({log}{L}10-50{keV}\\gt 43.3, R={0.46}-0.09+0.08) or lightly obscured ({log}{N}{{H}}≤slant 23, R={0.59}-0.10+0.09) objects. (4) The ratio of the luminosity of the [{{O}} {{IV}}] 25.89 μm line to the X-ray luminosity is significantly smaller in AGNs with lower soft X-ray scattering fractions, suggesting that the former luminosity underestimates the intrinsic power of an AGN buried in a torus of small opening angle.

  11. Combined urea-thin layer chromatography and silver nitrate-thin layer chromatography for micro separation and determination of hard-to-detect branched chain fatty acids in natural lipids.

    PubMed

    Yan, Yuanyuan; Wang, Xingguo; Liu, Yijun; Xiang, Jingying; Wang, Xiaosan; Zhang, Huijun; Yao, Yunping; Liu, Ruijie; Zou, Xiaoqiang; Huang, Jianhua; Jin, Qingzhe

    2015-12-18

    A simple, fast and efficient procedure was developed for micro separation and enrichment of branched chain fatty acids (BCFA) from natural products using successive thin layer chromatography (TLC) technique coupling novel urea-TLC with AgNO3-TLC, which rely on the formation of urea adduction and AgNO3 bonding in methanol. These natural lipids contain a significant amount of straight chain fatty acids (FA). Fresh and fast urea-TLC and AgNO3-TLC plate making techniques were developed with more even coating and less coating material contamination before being utilized for separation. Goat milk fat was used as a model. Various experimental parameters that affect urea-TLC and AgNO3-TLC separation of BCFA were investigated and optimized, including coating of urea, concentration of original oil sample, mobile phase and sample application format. High efficiency of removal of straight chain FA was achieved with a low amount of sample in an easy and fast way. A total BCFA mix with much higher purity than previous studies was successfully achieved. The developed method has also been applied for the concentration and analysis of BCFA in cow milk fat and Anchovy oil.

  12. Ordering of hard particles between hard walls

    NASA Astrophysics Data System (ADS)

    Chrzanowska, A.; Teixeira, P. I. C.; Ehrentraut, H.; Cleaver, D. J.

    2001-05-01

    The structure of a fluid of hard Gaussian overlap particles of elongation κ = 5, confined between two hard walls, has been calculated from density-functional theory and Monte Carlo simulations. By using the exact expression for the excluded volume kernel (Velasco E and Mederos L 1998 J. Chem. Phys. 109 2361) and solving the appropriate Euler-Lagrange equation entirely numerically, we have been able to extend our theoretical predictions into the nematic phase, which had up till now remained relatively unexplored due to the high computational cost. Simulation reveals a rich adsorption behaviour with increasing bulk density, which is described semi-quantitatively by the theory without any adjustable parameters.

  13. Ureilite Thin Section Preparation

    NASA Technical Reports Server (NTRS)

    Harrington, R.; Righter, K.

    2014-01-01

    Preparing thin and thick sections of ureilite type meteorites is a challenge that can confound even the most experienced section preparer. A common characteristic of these samples is the presence of carbon phases, particularly nanodiamonds, in the matrix along silicate grain boundaries, fractures, and cleavage plains [1]. The extreme hardness of the nanodiamonds presents a challenge to the section preparer in the form of high surface relief on the section. This hard material also causes considerable wear and tear on equipment and materials that are used for making the sections. These issues will be discussed and potentially helpful measures will be presented.

  14. Hardness Tester for Polyur

    NASA Technical Reports Server (NTRS)

    Hauser, D. L.; Buras, D. F.; Corbin, J. M.

    1987-01-01

    Rubber-hardness tester modified for use on rigid polyurethane foam. Provides objective basis for evaluation of improvements in foam manufacturing and inspection. Typical acceptance criterion requires minimum hardness reading of 80 on modified tester. With adequate correlation tests, modified tester used to measure indirectly tensile and compressive strengths of foam.

  15. Session: Hard Rock Penetration

    SciTech Connect

    Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hard Rock Penetration - Summary'' by George P. Tennyson, Jr.; ''Overview - Hard Rock Penetration'' by James C. Dunn; ''An Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.

  16. Erosion testing of hard materials and coatings

    SciTech Connect

    Hawk, Jeffrey A.

    2005-04-29

    Erosion is the process by which unconstrained particles, usually hard, impact a surface, creating damage that leads to material removal and component failure. These particles are usually very small and entrained in fluid of some type, typically air. The damage that occurs as a result of erosion depends on the size of the particles, their physical characteristics, the velocity of the particle/fluid stream, and their angle of impact on the surface of interest. This talk will discuss the basics of jet erosion testing of hard materials, composites and coatings. The standard test methods will be discussed as well as alternative approaches to determining the erosion rate of materials. The damage that occurs will be characterized in genera1 terms, and examples will be presented for the erosion behavior of hard materials and coatings (both thick and thin).

  17. Biomimetic thin film deposition

    NASA Astrophysics Data System (ADS)

    Rieke, P. C.; Campbell, A. A.; Tarasevich, B. J.; Fryxell, G. E.; Bentjen, S. B.

    1991-04-01

    Surfaces derivatized with organic functional groups were used to promote the deposition of thin films of inorganic minerals. These derivatized surfaces were designed to mimic the nucleation proteins that control mineral deposition during formation of bone, shell, and other hard tissues in living organisms. By the use of derivatized substrates control was obtained over the phase of mineral deposited, the orientation of the crystal lattice and the location of deposition. These features are of considerable importance in many technically important thin films, coatings, and composite materials. Methods of derivatizing surfaces are considered and examples of controlled mineral deposition are presented.

  18. Dynamic hardness of metals

    NASA Astrophysics Data System (ADS)

    Liang, Xuecheng

    Dynamic hardness (Pd) of 22 different pure metals and alloys having a wide range of elastic modulus, static hardness, and crystal structure were measured in a gas pulse system. The indentation contact diameter with an indenting sphere and the radius (r2) of curvature of the indentation were determined by the curve fitting of the indentation profile data. r 2 measured by the profilometer was compared with that calculated from Hertz equation in both dynamic and static conditions. The results indicated that the curvature change due to elastic recovery after unloading is approximately proportional to the parameters predicted by Hertz equation. However, r 2 is less than the radius of indenting sphere in many cases which is contradictory to Hertz analysis. This discrepancy is believed due to the difference between Hertzian and actual stress distributions underneath the indentation. Factors which influence indentation elastic recovery were also discussed. It was found that Tabor dynamic hardness formula always gives a lower value than that directly from dynamic hardness definition DeltaE/V because of errors mainly from Tabor's rebound equation and the assumption that dynamic hardness at the beginning of rebound process (Pr) is equal to kinetic energy change of an impact sphere over the formed crater volume (Pd) in the derivation process for Tabor's dynamic hardness formula. Experimental results also suggested that dynamic to static hardness ratio of a material is primarily determined by its crystal structure and static hardness. The effects of strain rate and temperature rise on this ratio were discussed. A vacuum rotating arm apparatus was built to measure Pd at 70, 127, and 381 mum sphere sizes, these results exhibited that Pd is highly depended on the sphere size due to the strain rate effects. P d was also used to substitute for static hardness to correlate with abrasion and erosion resistance of metals and alloys. The particle size effects observed in erosion were

  19. Organizing Your Hard Disk.

    ERIC Educational Resources Information Center

    Stocker, H. Robert; Hilton, Thomas S. E.

    1991-01-01

    Suggests strategies that make hard disk organization easy and efficient, such as making, changing, and removing directories; grouping files by subject; naming files effectively; backing up efficiently; and using PATH. (JOW)

  20. Radiation from hard objects

    SciTech Connect

    Canavan, G.H.

    1997-02-01

    The inference of the diameter of hard objects is insensitive to radiation efficiency. Deductions of radiation efficiency from observations are very sensitive - possibly overly so. Inferences of the initial velocity and trajectory vary similarly, and hence are comparably sensitive.

  1. Laser thermographic technologies for hard copy recording

    NASA Astrophysics Data System (ADS)

    Bessmel'tsev, Viktor P.; Baev, Sergej G.

    1995-04-01

    Methods of hard copies recording based on thermal interaction of the beam from CO2 or YAG lasers with various kinds of films on any substrates have been developed. The recording processes are single-step and require no additional development. Among them are: (1) Laser thermodestruction of thin mask layers or of a material surface on any kinds of substrates. (2) Laser thermochemical reactions of thermal decomposition of metal salts in solid state phase on a surface of various hygroscopic substrates. The laser recording devices using the methods, described above have been developed and are manufactured now; they allow one to record hard copies with a size of up to 27 X 31 inches, a resolution of 4000 dpi.

  2. Budgeting in Hard Times.

    ERIC Educational Resources Information Center

    Parrino, Frank M.

    2003-01-01

    Interviews with school board members and administrators produced a list of suggestions for balancing a budget in hard times. Among these are changing calendars and schedules to reduce heating and cooling costs; sharing personnel; rescheduling some extracurricular activities; and forming cooperative agreements with other districts. (MLF)

  3. Running in Hard Times

    ERIC Educational Resources Information Center

    Berry, John N., III

    2009-01-01

    Roberta Stevens and Kent Oliver are campaigning hard for the presidency of the American Library Association (ALA). Stevens is outreach projects and partnerships officer at the Library of Congress. Oliver is executive director of the Stark County District Library in Canton, Ohio. They have debated, discussed, and posted web sites, Facebook pages,…

  4. CSI: Hard Drive

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2008-01-01

    Acting on information from students who reported seeing a classmate looking at inappropriate material on a school computer, school officials used forensics software to plunge the depths of the PC's hard drive, searching for evidence of improper activity. Images were found in a deleted Internet Explorer cache as well as deleted file space.…

  5. Unemployment: Hard-Core or Hard-Shell?

    ERIC Educational Resources Information Center

    Lauer, Robert H.

    1972-01-01

    The term hard-core'' makes the unemployed culpable; the term hard shell'' shifts the burden to the employer, and the evidence from the suburban plant indicates that a substantial part of the problem must lie there. (DM)

  6. Super-Hard Superconductivity

    NASA Astrophysics Data System (ADS)

    Adams, Philip; Prozorov, Ruslan

    2005-03-01

    We present the magnetic response of Type-II superconductivity in the extreme pinning limit, where screening currents within an order of magnitude of the Ginzburg-Landau depairing critical current density develop upon the application of a magnetic field. We show that this ``super-hard'' limit is well approximated in highly disordered, cold drawn, Nb wire whose magnetization response is characterized by a cascade of Meissner-like phases, each terminated by a catastrophic collapse of the magnetization. Direct magneto-optic measurements of the flux penetration depth in the virgin magnetization branch are in excellent agreement with the exponential model in which Jc(B)=Jco(-B/Bo), where Jco˜5x10^6 A/cm^2 for Nb. The implications for the fundamental limiting hardness of a superconductor will be discussed.

  7. Hard metal composition

    DOEpatents

    Sheinberg, H.

    1983-07-26

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 wt % boron carbide and the remainder a metal mixture comprising from 70 to 90% tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 and 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  8. Hard metal composition

    DOEpatents

    Sheinberg, Haskell

    1986-01-01

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  9. A Model for the Oxidation of ZrB2, HfB2 and TiB2 (Postprint)

    DTIC Science & Technology

    2007-03-01

    appropriate thermodynamic data and the appropriate physical properties such as molecular weight,0.00055 0.00060 iction tal (Fenter) , 1hr 00 °C 1 100 0.0004...diborides of Zr, Hf and Ti in the temperature range of ~1000– 1800 °C was formulated. Available thermodynamic data and literature data for vapor...behavior of the diborides of Zr, Hf and Ti in the temperature range of 1000– 1800 C was formulated. Available thermodynamic data and literature data for

  10. Nanomechanics of hard films on compliant substrates.

    SciTech Connect

    Reedy, Earl David, Jr.; Emerson, John Allen; Bahr, David F.; Moody, Neville Reid; Zhou, Xiao Wang; Hales, Lucas; Adams, David Price; Yeager,John; Nyugen, Thao D.; Corona, Edmundo; Kennedy, Marian S.; Cordill, Megan J.

    2009-09-01

    a result, our understanding of the critical relationship between adhesion, properties, and fracture for hard films on compliant substrates is limited. To address this issue, we integrated nanomechanical testing and mechanics-based modeling in a program to define the critical relationship between deformation and fracture of nanoscale films on compliant substrates. The approach involved designing model film systems and employing nano-scale experimental characterization techniques to isolate effects of compliance, viscoelasticity, and plasticity on deformation and fracture of thin hard films on substrates that spanned more than two orders of compliance magnitude exhibit different interface structures, have different adhesion strengths, and function differently under stress. The results of this work are described in six chapters. Chapter 1 provides the motivation for this work. Chapter 2 presents experimental results covering film system design, sample preparation, indentation response, and fracture including discussion on the effects of substrate compliance on fracture energies and buckle formation from existing models. Chapter 3 describes the use of analytical and finite element simulations to define the role of substrate compliance and film geometry on the indentation response of thin hard films on compliant substrates. Chapter 4 describes the development and application of cohesive zone model based finite element simulations to determine how substrate compliance affects debond growth. Chapter 5 describes the use of molecular dynamics simulations to define the effects of substrate compliance on interfacial fracture of thin hard tungsten films on silicon substrates. Chapter 6 describes the Workshops sponsored through this program to advance understanding of material and system behavior.

  11. Hard Metal Disease

    PubMed Central

    Bech, A. O.; Kipling, M. D.; Heather, J. C.

    1962-01-01

    In Great Britain there have been no published reports of respiratory disease occurring amongst workers in the hard metal (tungsten carbide) industry. In this paper the clinical and radiological findings in six cases and the pathological findings in one are described. In two cases physiological studies indicated mild alveolar diffusion defects. Histological examination in a fatal case revealed diffuse pulmonary interstitial fibrosis with marked peribronchial and perivascular fibrosis and bronchial epithelial hyperplasia and metaplasia. Radiological surveys revealed the sporadic occurrence and low incidence of the disease. The alterations in respiratory mechanics which occurred in two workers following a day's exposure to dust are described. Airborne dust concentrations are given. The industrial process is outlined and the literature is reviewed. The toxicity of the metals is discussed, and our findings are compared with those reported from Europe and the United States. We are of the opinion that the changes which we would describe as hard metal disease are caused by the inhalation of dust at work and that the component responsible may be cobalt. Images PMID:13970036

  12. Characterization of Ta-B-C nanostructured hard coatings

    NASA Astrophysics Data System (ADS)

    Buršík, J.; Buršíková, V.; Souček, P.; Zábranský, L.; Vašina, P.

    2017-02-01

    Microstructure and mechanical properties of Ta-B-C nanocrystalline layers prepared by magnetron sputtering were studied. DC magnetron sputtering was used to prepare thin layers on rotated substrates. Various deposition parameters were tested. Microstructure of layers was studied by means of scanning and transmission electron microscopy on thin lamellar cross sections prepared using a focussed ion beam. Both undisturbed layers and the volume under relatively large indentation prints (load of 1 N) were observed. The microstructure observations were correlated with mechanical properties characterized by means of nanoindentation experiments in both the static and the dynamic loading regime. Elastic modulus, indentation hardness and fracture resistance of prepared nanostructured coatings were evaluated and discussed.

  13. Elastic, Plastic, Cracking Aspects of the Hardness of Materials

    NASA Astrophysics Data System (ADS)

    Armstrong, R. W.; Elban, W. L.; Walley, S. M.

    2013-03-01

    The hardness properties of materials are tracked from early history until the present time. Emphasis is placed on the hardness test being a useful probe for determining the local elastic, plastic and cracking properties of single crystal, polycrystalline, polyphase or amorphous materials. Beginning from connection made between individual hardness pressure measurements and the conventional stress-strain properties of polycrystalline materials, the newer consideration is described of directly specifying a hardness-type stress-strain relationship based on a continuous loading curve, particularly, as obtained with a spherical indenter. Such effort has received impetus from order-of-magnitude improvements in load and displacement measuring capabilities that are demonstrated for nanoindentation testing. Details of metrology assessments involved in various types of hardness tests are reviewed. A compilation of measurements is presented for the separate aspects of Hertzian elastic, dislocation-mechanics-based plasticity and indentation-fracture-mechanics-based cracking behaviors of materials, including elastic and plastic deformation rate effects. A number of test applications are reviewed, most notably involving the hardness of thin film materials and coatings.

  14. Overview: Hard Rock Penetration

    SciTech Connect

    Dunn, J.C.

    1992-08-01

    The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry/DOE cost shared projects of the Geothermal Drilling organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure drilling fluid outflow was tested extensively during Long Valley drilling. Results show that this meter is rugged, reliable, and can provide useful measurements of small differences in fluid inflow and outflow rates. By providing early indications of fluid gain or loss, improved control of blow-out and lost circulation problems during geothermal drilling can be expected. In the area of downhole tools for lost circulation control, the concept of a downhole injector for injecting a two-component, fast-setting cementitious mud was developed. DOE filed a patent application for this concept during FY 91. The design criteria for a high-temperature potassium, uranium, thorium logging tool featuring a downhole data storage computer were established, and a request for proposals was submitted to tool development companies. The fundamental theory of acoustic telemetry in drill strings was significantly advanced through field experimentation and analysis. A new understanding of energy loss mechanisms was developed.

  15. Overview - Hard Rock Penetration

    SciTech Connect

    Dunn, James C.

    1992-03-24

    The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry/DOE cost shared projects of the Geothermal Drilling Organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure drilling fluid outflow was tested extensively during Long Valley drilling. Results show that this meter is rugged, reliable, and can provide useful measurements of small differences in fluid inflow and outflow rates. By providing early indications of fluid gain or loss, improved control of blow-out and lost circulation problems during geothermal drilling can be expected. In the area of downhole tools for lost circulation control, the concept of a downhole injector for injecting a two-component, fast-setting cementitious mud was developed. DOE filed a patent application for this concept during FY 91. The design criteria for a high-temperature potassium, uranium, thorium logging tool featuring a downhole data storage computer were established, and a request for proposals was submitted to tool development companies. The fundamental theory of acoustic telemetry in drill strings was significantly advanced through field experimentation and analysis. A new understanding of energy loss mechanisms was developed.

  16. Overview: Hard Rock Penetration

    SciTech Connect

    Dunn, J.C.

    1992-01-01

    The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry/DOE cost shared projects of the Geothermal Drilling organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure drilling fluid outflow was tested extensively during Long Valley drilling. Results show that this meter is rugged, reliable, and can provide useful measurements of small differences in fluid inflow and outflow rates. By providing early indications of fluid gain or loss, improved control of blow-out and lost circulation problems during geothermal drilling can be expected. In the area of downhole tools for lost circulation control, the concept of a downhole injector for injecting a two-component, fast-setting cementitious mud was developed. DOE filed a patent application for this concept during FY 91. The design criteria for a high-temperature potassium, uranium, thorium logging tool featuring a downhole data storage computer were established, and a request for proposals was submitted to tool development companies. The fundamental theory of acoustic telemetry in drill strings was significantly advanced through field experimentation and analysis. A new understanding of energy loss mechanisms was developed.

  17. Measuring the Hardness of Minerals

    ERIC Educational Resources Information Center

    Bushby, Jessica

    2005-01-01

    The author discusses Moh's hardness scale, a comparative scale for minerals, whereby the softest mineral (talc) is placed at 1 and the hardest mineral (diamond) is placed at 10, with all other minerals ordered in between, according to their hardness. Development history of the scale is outlined, as well as a description of how the scale is used…

  18. Hard-facing with electro-spark deposition. Final report

    SciTech Connect

    Kees, K.P.

    1983-01-01

    A common method to improve wear resistance of metals in rubbing contact is to increase their surface hardness. Electro-Spark Deposition is a process which uses capacitive discharge pulses of high current passing through a hard carbide electrode in contact with and scanning the metal surface to be hardened. The result is a thin, hard, adherent coating of carbide deposited with a minimum of heat influence on the substrate and a significant increase in wear life of the coated metal. Electro-Spark Deposition is similar to a micro-welding process. It is a simple, portable and inexpensive coating method, which has great potential for commercial utilization. This thesis is an in depth study of the parameters associated with the ESD process and the wear resistance of the coatings.

  19. Interfacial phenomena in hard-rod fluids

    NASA Astrophysics Data System (ADS)

    Shundyak, K. Y.

    2004-05-01

    This thesis addresses questions of interfacial ordering in hard-rod fluids at coexistence of the isotropic and nematic phases and in their contact with simple model substrates. It is organized as follows. Chapter II provides some background information about the relation between the statistical mechanical and thermodynamical level of descriptions of bulk hard-rod fluids, as well as introduces the asymptotically exact Onsager model, and some basic facts of interfacial thermodynamics. Chapter III represents studies of the simplest free IN interface in a fluid of monodisperse Onsager hard rods. For the analysis of this system we develop an efficient perturbative method to determine the (biaxial) one-particle distribution function in inhomogeneous systems. Studies of the free planar isotropic-nematic interfaces are continued in Chapter IV, where they are considered in binary mixtures of hard rods. For sufficiently different particle shapes the bulk phase diagrams of these mixtures exhibit a triple point, where an isotropic (I) phase coexists with two nematic phases (N1 and N2) of different composition. For all explored mixtures we find that upon approach of the triple point the IN2 interface shows complete wetting by an intervening N1 film. We compute the surface tension of isotropic-nematic interfaces, and find a remarkable increase with fractionation. These studies are complemented by an analysis of bulk phase behavior and interfacial properties of nonadditive binary mixtures of thin and thick hard rods in Chapter V. The formulation of this model was motivated by recent experiments in the group of Fraden, who explored the phase behavior of a mixture of viruses with different effective diameters. In our model, species of the same types are considered as interacting with the hard-core repulsive potential, whereas the excluded volume for dissimilar rods is taken to be larger (smaller) then for the pure hard rods. Such a nonadditivity enhances (reduces) fractionation at

  20. Rolling-contact fatigue resistance of hard coatings on bearing steels.

    SciTech Connect

    Erdemir, A.

    1999-08-18

    Ball- and roller-bearings of the 21st Century are expected to perform better and last longer while operating under more stringent conditions than before. To meet these great expectations, researchers have been constantly exploring new bearing designs or refining existing ones, optimizing microstructure and chemistry of bearing materials, and alternatively, they have been considering the use of thin hard coatings for improved bearing performance and durability. Already, some laboratory tests have demonstrated that hard nitride, carbide (such as TiN, TiC, etc.) and diamondlike carbon (DLC) coatings can be very effective in prolonging the fatigue lives of bearing steels. This paper provides an overview of the recent developments in hard coatings for bearing applications. Previous studies have demonstrated that thin, hard coatings can effectively prolong the fatigue lives of bearing steel substrates. In particular, thinner hard coatings (i.e., 0.2 - 1 {micro}m thick) provide exceptional improvements in the fatigue lives of bearing steel substrates. In contrast, thicker hard coatings suffer micro fracture and delamination when tested under high contact stresses, hence are ineffective and may even have a negative effect on bearing life. Overall, it was concluded that thin hard coatings may offer new possibilities for bearing industry in meeting the performance and durability needs of the 21st Century.

  1. Depositing highly adhesive optical thin films on acrylic substrates.

    PubMed

    Takahashi, Tomoaki; Harada, Toshinori; Murotani, Hiroshi; Matumoto, Shigeharu

    2014-02-01

    Optical thin films are used to control the reflectance and transmittance of optical components. However, conventional deposition technologies applicable to organic (plastic) substrates typically result in weak adhesion. We overcame this problem by using vacuum deposition in combination with sputtering to directly deposit a SiO2 optical thin film onto an acrylic resin substrate. We observed neither yellowing nor deformation. The hardness of the film is 2H as measured by the pencil hardness test, indicating successful modulation of optical properties without sacrificing substrate hardness.

  2. Beta Backscatter Measures the Hardness of Rubber

    NASA Technical Reports Server (NTRS)

    Morrissey, E. T.; Roje, F. N.

    1986-01-01

    Nondestructive testing method determines hardness, on Shore scale, of room-temperature-vulcanizing silicone rubber. Measures backscattered beta particles; backscattered radiation count directly proportional to Shore hardness. Test set calibrated with specimen, Shore hardness known from mechanical durometer test. Specimen of unknown hardness tested, and radiation count recorded. Count compared with known sample to find Shore hardness of unknown.

  3. Thin-film metal coated insulation barrier in a Josephson tunnel junction. [Patent application

    DOEpatents

    Hawkins, G.A.; Clarke, J.

    1975-10-31

    A highly stable, durable, and reproducible Josephson tunnel junction consists of a thin-film electrode of a hard superconductor, a thin oxide insulation layer over the electrode constituting a Josephson tunnel junction barrier, a thin-film layer of stabilizing metal over the barrier, and a second thin-film hard superconductive electrode over the stabilizing film. The thin stabilizing metal film is made only thick enough to limit penetration of the electrode material through the insulation layer so as to prevent a superconductive short.

  4. Breaking through with Thin-Client Technologies: A Cost Effective Approach for Academic Libraries.

    ERIC Educational Resources Information Center

    Elbaz, Sohair W.; Stewart, Christofer

    This paper provides an overview of thin-client/server computing in higher education. Thin-clients are like PCs in appearance, but they do not house hard drives or localized operating systems and cannot function without being connected to a server. Two types of thin-clients are described: the Network Computer (NC) and the Windows Terminal (WT).…

  5. Nanoindentation hardness of mineralized tissues.

    PubMed

    Oyen, Michelle L

    2006-01-01

    A series elastic and plastic deformation model [Sakai, M., 1999. The Meyer hardness: a measure for plasticity? Journal of Materials Research 14(9), 3630-3639] is used to deconvolute the resistance to plastic deformation from the plane strain modulus and contact hardness parameters obtained in a nanoindentation test. Different functional dependencies of contact hardness on the plane strain modulus are examined. Plastic deformation resistance values are computed from the modulus and contact hardness for engineering materials and mineralized tissues. Elastic modulus and plastic deformation resistance parameters are used to calculate elastic and plastic deformation components, and to examine the partitioning of indentation deformation between elastic and plastic. Both the numerical values of plastic deformation resistance and the direct computation of deformation partitioning reveal the intermediate mechanical responses of mineralized composites when compared with homogeneous engineering materials.

  6. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... one of a new generation of instruments flying aboard the NASA Earth Observing System's Terra satellite, views Earth with nine cameras ... of thin cirrus minutes after MISR imaged the cloud from space. At the same time, another NASA high-altitude jet, the WB-57, flew right ...

  7. Thin Film?

    NASA Astrophysics Data System (ADS)

    Kariper, İ. Afşin

    2014-09-01

    This study focuses on the critical surface tension of lead sulfite (PbSO3) crystalline thin film produced with chemical bath deposition on substrates (commercial glass).The PbSO3 thin films were deposited at room temperature at different deposition times. The structural properties of the films were defined and examined according to X-ray diffraction (XRD) and the XRD results such as dislocation density, average grain size, and no. of crystallites per unit area. Atomic force microscopy was used to measure the film thickness and the surface properties. The critical surface tension of the PbSO3 thin films was measured with an optical tensiometer instrument and calculated using the Zisman method. The results indicated that the critical surface tension of films changed in accordance with the average grain size and film thickness. The film thickness increased with deposition time and was inversely correlated with surface tension. The average grain size increased according to deposition time and was inversely correlated with surface tension.

  8. Future hard disk drive systems

    NASA Astrophysics Data System (ADS)

    Wood, Roger

    2009-03-01

    This paper briefly reviews the evolution of today's hard disk drive with the additional intention of orienting the reader to the overall mechanical and electrical architecture. The modern hard disk drive is a miracle of storage capacity and function together with remarkable economy of design. This paper presents a personal view of future customer requirements and the anticipated design evolution of the components. There are critical decisions and great challenges ahead for the key technologies of heads, media, head-disk interface, mechanics, and electronics.

  9. Magnetic levitation for hard superconductors

    SciTech Connect

    Kordyuk, A.A.

    1998-01-01

    An approach for calculating the interaction between a hard superconductor and a permanent magnet in the field-cooled case is proposed. The exact solutions were obtained for the point magnetic dipole over a flat ideally hard superconductor. We have shown that such an approach is adaptable to a wide practical range of melt-textured high-temperature superconductors{close_quote} systems with magnetic levitation. In this case, the energy losses can be calculated from the alternating magnetic field distribution on the superconducting sample surface. {copyright} {ital 1998 American Institute of Physics.}

  10. Dynamic indentation hardness of materials

    NASA Astrophysics Data System (ADS)

    Koeppel, Brian James

    Indentation hardness is one of the simplest and most commonly used measures for quickly characterizing material response under static loads. Hardness may mean resistance to cutting to a machinist, resistance to wear to a tribologist, or a measure of flow stress to a design engineer. In this simple technique, a predetermined force is applied to an indenter for 5-30 seconds causing it to penetrate a specimen. By measuring the load and the indentation size, a hardness value is determined. However, the rate of deformation during indenter penetration is of the order of 10sp{-4}\\ ssp{-1}. In most practical applications, such as high speed machining or impact, material deforms at strain rates in excess of 10sp3{-}10sp5\\ ssp{-1}. At such high rates, it is well established that the plastic behavior of materials is considerably different from their static counterpart. For example, materials exhibit an increase in their yield stress, flow stress, fracture stress, and fracture toughness at high strain rates. Hence, the use of static hardness as an indicator of material response under dynamic loads may not be appropriate. Accordingly, a simple dynamic indentation hardness tester is developed for characterizing materials at strain rates similar to those encountered in realistic situations. The experimental technique uses elastic stress wave propagation phenomena in a slender rod. The technique is designed to deliver a single indentation load of 100-200 mus duration. Similar to static measurements, the dynamic hardness is determined from the measured load and indentation size. Hardness measurements on a range of metals have revealed that the dynamic hardness is consistently greater than the static hardness. The increase in hardness is strongly dependent on the crystal structure of the material. The observed trends in hardness are also found to be consistent with the yield and flow stresses of these materials under uniaxial compression. Therefore, it is suggested that the

  11. Surface modulation of dental hard tissues

    NASA Astrophysics Data System (ADS)

    Tantbirojn, Daranee

    Tooth surfaces play a central role in the equilibrium of dental hard tissues, in which contrasting processes lead to loss or deposition of materials. The central interest of this Thesis was the modulation of tooth surfaces to control such equilibrium. Four specific studies were carried out to investigate different classes of surface modulating agents. These are: (1) Ionic modulation of the enamel surface to enhance stain removal . Dental stain is the most apparent form of tooth surface deposit. The nature of extrinsic stain in terms of spatial chemical composition was studied by using electron probe microanalysis. An ionic surface modulating agent, sodium tripolyphosphate (STPP), was evaluated. Image analysis methodologies were developed and the ability of STPP in stain removal was proved. (2) Thin film modulation with substantive polymeric coating and the effect on in vitro enamel de/re-mineralization . A novel polymeric coating that formed a thin film on the tooth surface was investigated for its inhibitory effect on artificial enamel caries, without interfering with the remineralization process. The preventive effect was distinct, but the mineral redeposition was questionable. (3) Thick film modulation with fluoride containing sealants and the effect on in vitro enamel and root caries development. Fluoride incorporated into resin material is an example of combining different classes of surface modulating agents to achieve an optimal outcome. A proper combination, such as in resin modified glass ionomer, showed in vitro caries inhibitory effect beyond the material boundary in both enamel and dentin. (4) Thick film modulation with dental adhesives and the determination of adhesion to dentin. Dentin adhesives modulate intracoronal tooth surfaces by enhancing adhesion to restorative materials. Conventional nominal bond tests were inadequate to determine the performance of current high strength adhesives. It was shown that interfacial fracture toughness test was more

  12. Mechanics of an Asymmetric Hard-Soft Lamellar Nanomaterial.

    PubMed

    Shi, Weichao; Fredrickson, Glenn H; Kramer, Edward J; Ntaras, Christos; Avgeropoulos, Apostolos; Demassieux, Quentin; Creton, Costantino

    2016-02-23

    Nanolayered lamellae are common structures in nanoscience and nanotechnology, but most are nearly symmetric in layer thickness. Here, we report on the structure and mechanics of highly asymmetric and thermodynamically stable soft-hard lamellar structures self-assembled from optimally designed PS1-(PI-b-PS2)3 miktoarm star block copolymers. The remarkable mechanical properties of these strong and ductile PS (polystyrene)-based nanomaterials can be tuned over a broad range by varying the hard layer thickness while maintaining the soft layer thickness constant at 13 nm. Upon deformation, thin PS lamellae (<100 nm) exhibited kinks and predamaged/damaged grains, as well as cavitation in the soft layers. In contrast, deformation of thick lamellae (>100 nm) manifests cavitation in both soft and hard nanolayers. In situ tensile-SAXS experiments revealed the evolution of cavities during deformation and confirmed that the damage in such systems reflects both plastic deformation by shear and residual cavities. The aspects of the mechanics should point to universal deformation behavior in broader classes of asymmetric hard-soft lamellar materials, whose properties are just being revealed for versatile applications.

  13. Metrics for Hard Goods Merchandising.

    ERIC Educational Resources Information Center

    Cooper, Gloria S., Ed.; Magisos, Joel H., Ed.

    Designed to meet the job-related metric measurement needs of students interested in hard goods merchandising, this instructional package is one of five for the marketing and distribution cluster, part of a set of 55 packages for metric instruction in different occupations. The package is intended for students who already know the occupational…

  14. Playing the Numbers: Hard Choices

    ERIC Educational Resources Information Center

    Doyle, William R.

    2009-01-01

    Stateline.org recently called this recession the worst in 50 years for state budgets. As has been the case in past economic downturns, higher education looks to be particularly hard hit. Funds from the American Recovery and Relief Act may have postponed some of the difficulty for many colleges and universities, but the outlook for public higher…

  15. Hard Trying and These Recipes

    ERIC Educational Resources Information Center

    Atwell, Nancie

    2003-01-01

    Writers thrive when they are motivated to work hard, have regular opportunities to practice and reflect, and benefit from a knowledgeable teacher who knows writing. Student feedback to lessons during writing workshop helped guide Nancie Atwell in her quest to provide the richest and most efficient path to better writing.

  16. FATIGUE OF BIOMATERIALS: HARD TISSUES

    PubMed Central

    Arola, D.; Bajaj, D.; Ivancik, J.; Majd, H.; Zhang, D.

    2009-01-01

    The fatigue and fracture behavior of hard tissues are topics of considerable interest today. This special group of organic materials comprises the highly mineralized and load-bearing tissues of the human body, and includes bone, cementum, dentin and enamel. An understanding of their fatigue behavior and the influence of loading conditions and physiological factors (e.g. aging and disease) on the mechanisms of degradation are essential for achieving lifelong health. But there is much more to this topic than the immediate medical issues. There are many challenges to characterizing the fatigue behavior of hard tissues, much of which is attributed to size constraints and the complexity of their microstructure. The relative importance of the constituents on the type and distribution of defects, rate of coalescence, and their contributions to the initiation and growth of cracks, are formidable topics that have not reached maturity. Hard tissues also provide a medium for learning and a source of inspiration in the design of new microstructures for engineering materials. This article briefly reviews fatigue of hard tissues with shared emphasis on current understanding, the challenges and the unanswered questions. PMID:20563239

  17. Hard x-ray phase contrast imaging of black lipid membranes

    SciTech Connect

    Beerlink, A.; Mell, M.; Tolkiehn, M.; Salditt, T.

    2009-11-16

    We report hard x-ray phase contrast imaging of black lipid membranes, freely suspended over a micromachined aperture in an aqueous solution. Biomolecular and organic substances can thus be probed in hydrated environments by parallel beam propagation imaging, using coherent multi-kilo-electronvolt x-ray radiation. The width of the thinning film can be resolved from analysis of the intensity fringes in the Fresnel diffraction regime down to about 200 nm. The thinning process, in which solvent is expelled from the space in between two opposing monolayers, is monitored, and the domain walls between coexisting domains of swollen and thinned membrane patches are characterized.

  18. Hard processes in hadronic interactions

    SciTech Connect

    Satz, H. |; Wang, X.N.

    1995-07-01

    Quantum chromodynamics is today accepted as the fundamental theory of strong interactions, even though most hadronic collisions lead to final states for which quantitative QCD predictions are still lacking. It therefore seems worthwhile to take stock of where we stand today and to what extent the presently available data on hard processes in hadronic collisions can be accounted for in terms of QCD. This is one reason for this work. The second reason - and in fact its original trigger - is the search for the quark-gluon plasma in high energy nuclear collisions. The hard processes to be considered here are the production of prompt photons, Drell-Yan dileptons, open charm, quarkonium states, and hard jets. For each of these, we discuss the present theoretical understanding, compare the resulting predictions to available data, and then show what behaviour it leads to at RHIC and LHC energies. All of these processes have the structure mentioned above: they contain a hard partonic interaction, calculable perturbatively, but also the non-perturbative parton distribution within a hadron. These parton distributions, however, can be studied theoretically in terms of counting rule arguments, and they can be checked independently by measurements of the parton structure functions in deep inelastic lepton-hadron scattering. The present volume is the work of Hard Probe Collaboration, a group of theorists who are interested in the problem and were willing to dedicate a considerable amount of their time and work on it. The necessary preparation, planning and coordination of the project were carried out in two workshops of two weeks` duration each, in February 1994 at CERn in Geneva andin July 1994 at LBL in Berkeley.

  19. Soft metal plating enables hard metal seal to operate successfully in low temperature, high pressure environment

    NASA Technical Reports Server (NTRS)

    Lamvermeyer, D. J.

    1967-01-01

    Soft metal plating of hard metal lip seal enables successful operation of seal in a cryogenic fluid line under high pressure. The seal is coated with a thin film of 24 carat gold on the lip area to provide antigall and seal properties.

  20. Replicated Nickel Optics for the Hard-X-Ray Region

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian

    2005-01-01

    Replicated nickel optics has been used extensively in x-ray astronomy, most notable for the XMM/Newton mission. Thc combination of relative ease of fabrication and the inherent stability of full shell optics, make them FIJI attractive approach for medium-resolution, high-throughput applications. MSFC has been developing these optics for use in the hard-x-ray region. Efforts at improving the resolution of these, particularly the very-thin shells required to meet thc weight budget of future missions, will be described together with the prospects for significant improvements down to the 5-arcsec level.

  1. Micro-finish hard anodized coatings on aluminum

    SciTech Connect

    Steffani, C.

    1992-03-01

    The production of thin hard anodized coatings on Single Point Diamond Turned (SPDT) 6061-T6 aluminum has been studied. The investigation centered on producing a surface finish of less than 10 microinch after anodizing. By starting with a 2 microinch (AA) surface finish and controlling time, temperature, current density and solution chemistry, coatings with surface finishes of 8 microinch and a thickness of .0003 inch, are obtained. Surface roughness from several anodizing solutions is compared. The operational life of a PTFE sliding seal against a coated cylinder bore is used as verification of finish quality.

  2. Transport coefficients and mechanical response in hard-disk colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Zhang, Bo-Kai; Li, Jian; Chen, Kang; Tian, Wen-De; Ma, Yu-Qiang

    2016-11-01

    We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory. We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermal-activated barrier-hopping dynamics and mechanically accelerated motion. Dense hard disks exhibit phenomena such as softening elasticity, shear-thinning of viscosity, and yielding upon deformation, which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions. These phenomena can be ascribed to stress-induced “landscape tilting”. Quantitative comparisons of these phenomena between hard disks and hard spheres are presented. Interestingly, we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres. Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks. Project supported by the National Basic Research Program of China (Grant No. 2012CB821500) and the National Natural Science Foundation of China (Grant Nos. 21374073 and, 21574096).

  3. Thin film technologies II; Proceedings of the Meeting, Innsbruck, Austria, Apr. 15-17, 1986

    NASA Astrophysics Data System (ADS)

    Jacobsson, J. Roland

    1986-01-01

    Papers are presented on automated optical coating processes and thin film production with an optical thickness monitoring system; the ultrasonic precision cleaning of optical components prior to and after vacuum coating; a wideband antireflection coating design by the random search approach; a computer-aided design of thin film optical coatings; subjective and objective methods for surface inspection; and micro/ultramicro hardness measurements with insulating films. Topics discussed include optical absorption in amorphous semiconductor films; the optical properties of thin silicide layers; laser damage to optical coatings; and light scattering and characterization of thin films; ion and photon-beam assisted deposition of thin films; and low temperature photo-CVD silicon nitride characterization. Consideration is given to the measurement of absorption in thin films using laser calorimetry; coherence loss due to thin film interface roughness; the performance of sputter deposited multilayer X-ray mirrors; and the stability of hard coating filters.

  4. Transpecific microsatellites for hard pines.

    PubMed

    Shepherd, M.; Cross, M.; Maguire, L.; Dieters, J.; Williams, G.; Henry, J.

    2002-04-01

    Microsatellites are difficult to recover from large plant genomes so cross-specific utilisation is an important source of markers. Fifty microsatellites were tested for cross-specific amplification and polymorphism to two New World hard pine species, slash pine ( Pinus elliottii var. elliottii) and Caribbean pine ( P. caribaea var. hondurensis). Twenty-nine (58%) markers amplified in both hard pine species, and 23 of these 29 were polymorphic. Soft pine (subgenus Strobus) microsatellite markers did amplify, but none were polymorphic. Pinus elliottii var. elliottii and P. caribaea var. hondurensis showed mutational changes in the flanking regions and the repeat motif that were informative for Pinus spp. phylogenetic relationships. Most allele length variation could be attributed to variability in repeat unit number. There was no evidence for ascertainment bias.

  5. Ultrasonic material hardness depth measurement

    DOEpatents

    Good, Morris S.; Schuster, George J.; Skorpik, James R.

    1997-01-01

    The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part.

  6. Ultrasonic material hardness depth measurement

    DOEpatents

    Good, M.S.; Schuster, G.J.; Skorpik, J.R.

    1997-07-08

    The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part. 12 figs.

  7. Schwannoma of the hard palate

    PubMed Central

    Sahoo, Pradyumna Kumar; Mandal, Palash Kumar; Ghosh, Saradindu

    2014-01-01

    Schwannomas are benign encapsulated perineural tumors. The head and neck region is the most common site. Intraoral origin is seen in only 1% of cases, tongue being the most common site; its location in the palate is rare. We report a case of hard-palate schwannoma with bony erosion which was immunohistochemically confirmed. The tumor was excised completely intraorally. After two months of follow-up, the defect was found to be completely covered with palatal mucosa. PMID:25298716

  8. Rad-Hard Silicon Detectors

    NASA Astrophysics Data System (ADS)

    Giorgi, Marco

    2005-06-01

    For the next generation of High Energy Physics (HEP) Experiments silicon microstrip detectors working in harsh radiation environments with excellent performances are necessary. The irradiation causes bulk and surface damages that modify the electrical properties of the detector. Solutions like AC coupled strips, overhanging metal contact, <100> crystal lattice orientation, low resistivity n-bulk and Oxygenated substrate are studied for rad-hard detectors. The paper presents an outlook of these technologies.

  9. Microwave assisted hard rock cutting

    DOEpatents

    Lindroth, David P.; Morrell, Roger J.; Blair, James R.

    1991-01-01

    An apparatus for the sequential fracturing and cutting of subsurface volume of hard rock (102) in the strata (101) of a mining environment (100) by subjecting the volume of rock to a beam (25) of microwave energy to fracture the subsurface volume of rock by differential expansion; and , then bringing the cutting edge (52) of a piece of conventional mining machinery (50) into contact with the fractured rock (102).

  10. Why Are Drugs So Hard to Quit?

    MedlinePlus Videos and Cool Tools

    ... Quitting drugs is hard because addiction is a brain disease. Your brain is like a control tower that sends out ... and choices. Addiction changes the signals in your brain and makes it hard to feel OK without ...

  11. More Older Women Hitting the Bottle Hard

    MedlinePlus

    ... medlineplus.gov/news/fullstory_164321.html More Older Women Hitting the Bottle Hard Study found dramatic jump ... March 28, 2017 (HealthDay News) -- More older American women than ever are drinking -- and drinking hard, a ...

  12. Warren G. Harding and the Press.

    ERIC Educational Resources Information Center

    Whitaker, W. Richard

    There are many parallels between the Richard M. Nixon administration and Warren G. Harding's term: both Republicans, both touched by scandal, and both having a unique relationship with the press. But in Harding's case the relationship was a positive one. One of Harding's first official acts as president was to restore the regular White House news…

  13. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where falling...

  14. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or...

  15. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hard seed. 201.21 Section 201.21 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard...

  16. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hard seed. 201.30 Section 201.30 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed,...

  17. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  18. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  19. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  20. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  1. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  2. Analysis of dental hard tissue by computerized microdensitometry.

    PubMed

    Mallon, D E; Mellberg, J R

    1985-02-01

    One method of quantitating mineral content in thin sections of dental hard tissue is microdensitometry of contact radiographs. This method is often applied to analysis of artificial caries lesions. Because there is great inter- and intra-tooth variability, a single microdensitometric scan will not accurately reflect the content or distribution of mineral within an individual lesion, or within a group of lesions. To increase the number of replicates than can be handled routinely, a computer-driven microdensitometer has been used with a step series of aluminum and enamel to quantitate mineral content values at approximately 1-micron intervals. Accurate assessment of an individual lesion was made possible by averaging multiple scans of the lesion on each of several thin sections prepared from the lesion. Mean mineral profiles of treatment groups were then made from the profiles of the individual lesion. These data reduction techniques allowed for a large number of replicates to be used in the measurement of remineralization. The computerized microdensitometric system described here was developed to allow for an objective, quantitative analysis of the mineral content of dental hard tissue.

  3. The Hard Problem of Cooperation

    PubMed Central

    Eriksson, Kimmo; Strimling, Pontus

    2012-01-01

    Based on individual variation in cooperative inclinations, we define the “hard problem of cooperation” as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior. PMID:22792282

  4. The hard problem of cooperation.

    PubMed

    Eriksson, Kimmo; Strimling, Pontus

    2012-01-01

    Based on individual variation in cooperative inclinations, we define the "hard problem of cooperation" as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior.

  5. Radiation Hardness Assurance (RHA) Guideline

    NASA Technical Reports Server (NTRS)

    Campola, Michael J.

    2016-01-01

    Radiation Hardness Assurance (RHA) consists of all activities undertaken to ensure that the electronics and materials of a space system perform to their design specifications after exposure to the mission space environment. The subset of interests for NEPP and the REAG, are EEE parts. It is important to register that all of these undertakings are in a feedback loop and require constant iteration and updating throughout the mission life. More detail can be found in the reference materials on applicable test data for usage on parts.

  6. Radiation hard electronics for LHC

    NASA Astrophysics Data System (ADS)

    Raymond, M.; Millmore, M.; Hall, G.; Sachdeva, R.; French, M.; Nygård, E.; Yoshioka, K.

    1995-02-01

    A CMOS front end electronics chain is being developed by the RD20 collaboration for microstrip detector readout at LHC. It is based on a preamplifier and CR-RC filter, analogue pipeline and an analogue signal processor. Amplifiers and transistor test structures have been constructed and evaluated in detail using a Harris 1.2 μm radiation hardened CMOS process. Progress with larger scale elements, including 32 channel front end chips, is described. A radiation hard 128 channel chip, with a 40 MHz analogue multiplexer, is to be submitted for fabrication in July 1994 which will form the basis of the readout of the tracking system of the CMS experiment.

  7. Hard Scattering Studies at Jlab

    SciTech Connect

    Harutyun Avagyan; Peter Bosted; Volker Burkert; Latifa Elouadrhiri

    2005-09-01

    We present current activities and future prospects for studies of hard scattering processes using the CLAS detector and the CEBAF polarized electron beam. Kinematic dependences of single and double spin asymmetries have been measured in a wide kinematic range at CLAS with a polarized NH{sub 3} and unpolarized liquid hydrogen targets. It has been shown that the data are consistent with factorization and observed target and beam asymmetries are in good agreement with measurements performed at higher energies, suggesting that the high energy-description of the semi-inclusive DIS process can be extended to the moderate energies of JLab measurements.

  8. Thermopile detector radiation hard readout

    NASA Astrophysics Data System (ADS)

    Gaalema, Stephen; Van Duyne, Stephen; Gates, James L.; Foote, Marc C.

    2010-08-01

    The NASA Jupiter Europa Orbiter (JEO) conceptual payload contains a thermal instrument with six different spectral bands ranging from 8μm to 100μm. The thermal instrument is based on multiple linear arrays of thermopile detectors that are intrinsically radiation hard; however, the thermopile CMOS readout needs to be hardened to tolerate the radiation sources of the JEO mission. Black Forest Engineering is developing a thermopile readout to tolerate the JEO mission radiation sources. The thermal instrument and ROIC process/design techniques are described to meet the JEO mission requirements.

  9. Mechanics of an Asymmetric Hard-Soft Lamellar Nanomaterial

    SciTech Connect

    Shi, Weichao; Fredrickson, Glenn H.; Kramer, Edward J.; Ntaras, Christos; Avgeropoulos, Apostolos; Demassieux, Quentin; Creton, Costantino

    2016-03-24

    Nanolayered lamellae are common structures in nanoscience and nanotechnology, but most are nearly symmetric in layer thickness. Here, we report on the structure and mechanics of highly asymmetric and thermodynamically stable soft–hard lamellar structures self-assembled from optimally designed PS1-(PI-b-PS2)3 miktoarm star block copolymers. The remarkable mechanical properties of these strong and ductile PS (polystyrene)-based nanomaterials can be tuned over a broad range by varying the hard layer thickness while maintaining the soft layer thickness constant at 13 nm. Upon deformation, thin PS lamellae (<100 nm) exhibited kinks and predamaged/damaged grains, as well as cavitation in the soft layers. In contrast, deformation of thick lamellae (>100 nm) manifests cavitation in both soft and hard nanolayers. In situ tensile-SAXS experiments revealed the evolution of cavities during deformation and confirmed that the damage in such systems reflects both plastic deformation by shear and residual cavities. The aspects of the mechanics should point to universal deformation behavior in broader classes of asymmetric hard–soft lamellar materials, whose properties are just being revealed for versatile applications.

  10. The Development of Hard-X-Ray Optics at MSFC

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian D.; Elsner, R. F.; Engelhaupt, D. E.; Kolodziejczak, J. J.; ODell, S. L.; Speegle, C. O.; Weisskopf, M. C.; Six, Frank (Technical Monitor)

    2002-01-01

    We are fabricating optics for the hard-x-ray region using electroless nickel replication. The attraction of this process, which has been widely used elsewhere, is that the resulting full shell optics are inherently table and thus can have very good angular resolution. The challenge with this process is to develop lightweight optics (nickel has a relatively high density of 8.9 g / cu cm), and to keep down the costs of mandrel fabrication. We accomplished the former through the development of high-strength nickel alloys that permit very thin shells without fabrication- and handling-induced deformations. For the latter, we have utilized inexpensive grinding and diamond turning to figure the mandrels and then purpose-built polishing machines to finish the surface. In-house plating tanks and a simple water-bath separation system complete the process. To date we have built shells ranging in size from 5 cm diameter to 50 cm, and with thickness down to 100 micron. For our HERO (high energy replicated optics) balloon program, we are fabricating over 200 iridium-coated shells, 250 microns thick, for hard-x-ray imaging up to 75 keV. Early test results on these have indicated half-power-diameters of 15 arcsec. The status of these and other hard-x-ray optics will be reviewed.

  11. Hardness correlation for uranium and its alloys

    SciTech Connect

    Humphreys, D L; Romig, Jr, A D

    1983-03-01

    The hardness of 16 different uranium-titanium (U-Ti) alloys was measured on six (6) different hardness scales (R/sub A/, R/sub B/, R/sub C/, R/sub D/, Knoop, and Vickers). The alloys contained between 0.75 and 2.0 wt % Ti. All of the alloys were solutionized (850/sup 0/C, 1 h) and ice-water quenched to produce a supersaturated martensitic phase. A range of hardnesses was obtained by aging the samples for various times and temperatures. The correlation of various hardness scales was shown to be virtually identical to the hardness-scale correlation for steels. For more-accurate conversion from one hardness scale to another, least-squares-curve fits were determined for the various hardness-scale correlations. 34 figures, 5 tables.

  12. Hardness ratios of different neutron spectra.

    PubMed

    Tommasino, L; Tripathy, S P

    2004-01-01

    Extensive data have been gathered in the past on the response of different detectors, based on the registration of neutron-induced fissions in bismuth, gold, tantalum and thorium by the spark-replica counter and the thin film breakdown counter. These detectors make it possible to exploit the excellent characteristics of the fission reactions for the measurements of high-energy neutrons. Most of the investigations have been carried out at the quasi-monoenergetic neutron beam facility at The Svedberg Laboratory-TSL of the Uppsala University in cooperation with the Khlopin Radium Institute (KRI). The responses of different fission detectors in the neutron energy range 35-180 MeV have been evaluated: a region where the predictive power of available nuclear reaction models and codes is not reliable yet. For neutron energy >200 MeV, the fission-detector responses have been derived from the data of the proton fission cross sections. By using the ratio of the responses of these detectors, a simple and accurate way to evaluate the spectrum hardness can be obtained, thus providing a tool to obtain spectral information needed for neutron dosimetry without the need to know the entire spectrum. Extensive data have been already obtained for the high-energy neutron spectrum from the CERN concrete facility. In the present paper, the measured values of the response ratios for different fissile detectors exposed at the CERN facility are compared with those calculated for the spectra from the same facility and from different altitudes in the atmosphere, respectively.

  13. Hard and Soft Safety Verifications

    NASA Technical Reports Server (NTRS)

    Wetherholt, Jon; Anderson, Brenda

    2012-01-01

    The purpose of this paper is to examine the differences between and the effects of hard and soft safety verifications. Initially, the terminology should be defined and clarified. A hard safety verification is datum which demonstrates how a safety control is enacted. An example of this is relief valve testing. A soft safety verification is something which is usually described as nice to have but it is not necessary to prove safe operation. An example of a soft verification is the loss of the Solid Rocket Booster (SRB) casings from Shuttle flight, STS-4. When the main parachutes failed, the casings impacted the water and sank. In the nose cap of the SRBs, video cameras recorded the release of the parachutes to determine safe operation and to provide information for potential anomaly resolution. Generally, examination of the casings and nozzles contributed to understanding of the newly developed boosters and their operation. Safety verification of SRB operation was demonstrated by examination for erosion or wear of the casings and nozzle. Loss of the SRBs and associated data did not delay the launch of the next Shuttle flight.

  14. Thin Sections

    PubMed Central

    Peachey, Lee D.

    1958-01-01

    Knowledge of the thickness of sections is important for proper interpretation of electron micrographs. Therefore, the thicknesses of sections of n-butyl methacrylate polymer were determined by ellipsometry, and correlated with the color shown in reflected light. The results are: gray, thinner than 60 mµ; silver, 60 to 90 mµ; gold, 90 to 150 mµ; purple, 150 to 190 mµ; blue, 190 to 240 mµ; green, 240 to 280 mµ; and yellow, 280 to 320 mµ. These results agree well with optical theory and with previous published data for thin films. Sections, after cutting, are 30 to 40 per cent shorter than the face of the block from which they were cut. Only a small improvement results from allowing the sections to remain in the collecting trough at room temperature. Heating above room temperature, however, reduces this shortening, with a corresponding improvement in dimensions and spatial relationships in the sections. When the thickness of the section is considered in interpreting electron micrographs instead of considering the section to be two-dimensional, a more accurate interpretation is possible. The consideration of electron micrographs as arising from projections of many profiles from throughout the whole thickness of the section explains the apparent lack of continuity often observed in serial sections. It is believed that serial sections are actually continuous, but that the change in size of structure through the thickness of one section and the consideration of only the largest profile shown in the micrograph can account for the lack of continuity previously observed. PMID:13549493

  15. Hard x-ray photoelectron spectroscopy of chalcopyrite solar cell components

    NASA Astrophysics Data System (ADS)

    Gloskovskii, A.; Jenkins, C. A.; Ouardi, S.; Balke, B.; Fecher, G. H.; Dai, X.-F.; Gruhn, T.; Johnson, B.; Lauermann, I.; Caballero, R.; Kaufmann, C. A.; Felser, C.

    2012-02-01

    Hard x-ray photoelectron spectroscopy is used to examine the partial density of states of Cu(In,Ga)Se2 (CIGSe), a semiconducting component of solar cells. The investigated, thin Cu(In,Ga)Se2 films were produced by multi-stage co-evaporation. Details of the measured core level and valence band spectra are compared to the calculated density of states. The semiconducting type electronic structure of Cu(In,Ga)Se2 is clearly resolved in the hard x-ray photoelectron spectra.

  16. Recent developments of rare-earth-free hard-magnetic materials

    NASA Astrophysics Data System (ADS)

    Li, Da; Pan, DeSheng; Li, ShaoJie; Zhang, ZhiDong

    2016-01-01

    Recent advances in rare-earth-free hard-magnetic materials including magnetic bulk, thin films, nanocomposites and nanostructures are introduced. Since the costs of the rare-earth metals boosts up the price of the high-performance rare-earth permanent magnets, there is a much revived interest in various types of hard-magnetic materials based on rare-earth-free compounds. The 3d transition metals and their alloys with large coercivity and high Curie temperatures (working temperatures) are expected to overcome the disadvantages of rare-earth magnets. Making rare-earth-free magnets with a large energy product to meet tomorrow's energy needs is still a challenge.

  17. Functionally gradient hard carbon composites for improved adhesion and wear

    NASA Astrophysics Data System (ADS)

    Narayan, Roger Jagdish

    A new approach is proposed for fabricating biomedical devices that last longer and are more biocompatible than those presently available. In this approach, a bulk material is chosen that has desirable mechanical properties (low modulus, high strength, high ductility and high fatigue strength). This material is coated with corrosion-resistant, wear-resistant, hard, and biocompatible hard carbon films. One of the many forms of carbon, tetrahedral amorphous carbon, consists mainly of sp3-bonded atoms. Tetrahedral amorphous carbon possesses properties close to diamond in terms of hardness, atomic smoothness, and inertness. Tetrahedral amorphous carbon and diamond films usually contain large amounts of compressive and sometimes tensile stresses; adhesive failure from these stresses has limited widespread use of these materials. This research involves processing, characterization and modeling of functionally gradient tetrahedral amorphous carbon and diamond composite films on metals (cobalt-chromium and titanium alloys) and polymers (polymethylmethacrylate and polyethylene) used in biomedical applications. Multilayer discontinuous thin films of titanium carbide, titanium nitride, aluminum nitride, and tungsten carbide have been developed to control stresses and graphitization in diamond films. A morphology of randomly interconnected micron sized diamond crystallites provides increased toughness and stress reduction. Internal stresses in tetrahedral amorphous carbon were reduced via incorporation of carbide forming elements (silicon and titanium) and noncarbide forming elements (copper, platinum, and silver). These materials were produced using a novel target design during pulsed laser deposition. These alloying atoms reduce hardness and sp3-bonded carbon content, but increase adhesion and wear resistance. Silver and platinum provide the films with antimicrobial properties, and silicon provides bioactivity and aids bone formation. Bilayer coatings were created that couple

  18. Development of radiation hard scintillators

    SciTech Connect

    Markley, F.; Woods, D.; Pla-Dalmau, A.; Foster, G. ); Blackburn, R. )

    1992-05-01

    Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro.

  19. Hard X-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Rothschild, R. E.

    1981-01-01

    Past hard X-ray and lower energy satellite instruments are reviewed and it is shown that observation above 20 keV and up to hundreds of keV can provide much valuable information on the astrophysics of cosmic sources. To calculate possible sensitivities of future arrays, the efficiencies of a one-atmosphere inch gas counter (the HEAO-1 A-2 xenon filled HED3) and a 3 mm phoswich scintillator (the HEAO-1 A-4 Na1 LED1) were compared. Above 15 keV, the scintillator was more efficient. In a similar comparison, the sensitivity of germanium detectors did not differ much from that of the scintillators, except at high energies where the sensitivity would remain flat and not rise with loss of efficiency. Questions to be addressed concerning the physics of active galaxies and the diffuse radiation background, black holes, radio pulsars, X-ray pulsars, and galactic clusters are examined.

  20. Habitat Suitability Index Models: Hard clam

    USGS Publications Warehouse

    Mulholland, Rosemarie

    1984-01-01

    Two species of hard clams occur along the Atlantic and Gulf of Mexico coasts of North America: the southern hard clam, Mercenaria campechiensis Gmelin 1791, and the northern hard clam, ~lercenaria mercenaria Linne 1758 (Wells 1957b). The latter species, also commonly kno\\'m as the quahog, was formerly named Venus mercenaria. The two species are closely related, produce viable hybrids (Menzel and Menzel 1965), and may be a single species.

  1. 30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Distinctively colored hard hats or hard caps... Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color from those worn by experienced miners shall be worn...

  2. 30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Distinctively colored hard hats, or hard caps... STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1720-1 Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in...

  3. Effects of Phase Change and Oxygen Permeability in Oxide Scales on Oxidation Kinetics of ZrB2 and HfB2 (POSTPRINT)

    DTIC Science & Technology

    2009-11-01

    Materials,’’ SAMPE Quar- terly, 2 [3] 1–15 (1971). 10J. B. Berkowitz-Mattuck, ‘‘High-Temperature Oxidation III : Zirconium and Hafnium Diborides ,’’ J...1959). 30L. Kaufman, E. V. Clougherty, and J. B. Berkowitz-Mattuck, ‘‘Oxidation Characteristics of Hafnium and Zirconium Diboride ,’’ Trans. of Met. Soc...interface i B2O3(l)–B2O3(g) interface I. Introduction DIBORIDES of Zr and Hf are now well recognized as the mostpromising refractory materials that are

  4. Hardness of cubic solid solutions

    PubMed Central

    Gao, Faming

    2017-01-01

    We demonstrate that a hardening rule exists in cubic solid solutions with various combinations of ionic, covalent and metallic bonding. It is revealed that the hardening stress ∆τFcg is determined by three factors: shear modulus G, the volume fraction of solute atoms fv, and the size misfit degree δb. A simple hardening correlation in KCl-KBr solid-solution is proposed as ∆τFcg = 0.27 G. It is applied to calculate the hardening behavior of the Ag-Au, KCl-KBr, InP-GaP, TiN-TiC, HfN-HfC, TiC-NbC and ZrC-NbC solid-solution systems. The composition dependence of hardness is elucidated quantitatively. The BN-BP solid-solution system is quantitatively predicted. We find a hardening plateau region around the x = 0.55–0.85 in BNxP1−x, where BNxP1−x solid solutions are far harder than cubic BN. Because the prediction is quantitative, it sets the stage for a broad range of applications. PMID:28054659

  5. Hardness of cubic solid solutions

    NASA Astrophysics Data System (ADS)

    Gao, Faming

    2017-01-01

    We demonstrate that a hardening rule exists in cubic solid solutions with various combinations of ionic, covalent and metallic bonding. It is revealed that the hardening stress ∆τFcg is determined by three factors: shear modulus G, the volume fraction of solute atoms fv, and the size misfit degree δb. A simple hardening correlation in KCl-KBr solid-solution is proposed as ∆τFcg = 0.27 G. It is applied to calculate the hardening behavior of the Ag-Au, KCl-KBr, InP-GaP, TiN-TiC, HfN-HfC, TiC-NbC and ZrC-NbC solid-solution systems. The composition dependence of hardness is elucidated quantitatively. The BN-BP solid-solution system is quantitatively predicted. We find a hardening plateau region around the x = 0.55–0.85 in BNxP1‑x, where BNxP1‑x solid solutions are far harder than cubic BN. Because the prediction is quantitative, it sets the stage for a broad range of applications.

  6. Hard X-ray delays

    NASA Technical Reports Server (NTRS)

    Schwartz, Richard A.

    1986-01-01

    High time resolution hard X-ray rates with good counting statistics over 5 energy intervals were obtained using a large area balloon-borne scintillation detector during the 27 June 1980 solar flare. The impulsive phase of the flare was comprised of a series of major bursts of several to several tens of seconds long. Superimposed on these longer bursts are numerous smaller approximately 0.5 to 1.0 second spikes. The time profiles for different energies were cross-correlated for the major bursts. The rapid burst decay rates and the simultaneous peaks below 120 keV both indicate a rapid electron energy loss process. Thus, the flux profiles reflect the electron acceleration/injection process. The fast rate data was obtained by a burst memory in 8 and 32 msec resolution over the entire main impulsive phase. These rates will be cross-correlated to look for short time delays and to find rapid fluctuations. However, a cursory examination shows that almost all fluctuations, down to the 5% level, were resolved with 256 msec bins.

  7. Development of a radiation-hard CMOS process

    NASA Technical Reports Server (NTRS)

    Power, W. L.

    1983-01-01

    It is recommended that various techniques be investigated which appear to have the potential for improving the radiation hardness of CMOS devices for prolonged space flight mission. The three key recommended processing techniques are: (1) making the gate oxide thin. It has been shown that radiation degradation is proportional to the cube of oxide thickness so that a relatively small reduction in thickness can greatly improve radiation resistance; (2) cleanliness and contamination control; and (3) to investigate different oxide growth (low temperature dry, TCE and HCL). All three produce high quality clean oxides, which are more radiation tolerant. Technique 2 addresses the reduction of metallic contamination. Technique 3 will produce a higher quality oxide by using slow growth rate conditions, and will minimize the effects of any residual sodium contamination through the introduction of hydrogen and chlorine into the oxide during growth.

  8. Apparatus and process for deposition of hard carbon films

    DOEpatents

    Nyaiesh, Ali R.; Garwin, Edward L.

    1989-01-01

    A process and an apparatus for depositing thin, amorphous carbon films having extreme hardness on a substrate is described. An enclosed chamber maintained at less than atmospheric pressure houses the substrate and plasma producing elements. A first electrode is comprised of a cavity enclosed within an RF coil which excites the plasma. A substrate located on a second electrode is excited by radio frequency power applied to the substrate. A magnetic field confines the plasma produced by the first electrode to the area away from the walls of the chamber and focuses the plasma onto the substrate thereby yielding film deposits having higher purity and having more rapid buildup than other methods of the prior art.

  9. Hard X-Ray and Wide Focusing Telescopes

    NASA Technical Reports Server (NTRS)

    Gorenstein, Paul

    1998-01-01

    Studies are being carried out to compare the performance of several different separation materials used in the replication process. This report presents the results obtained during the second year of a program which consists of replicating smooth, thin substrates, depositing multilayer coatings upon them, and evaluating their performance. Replication and multilayer coatings are both critically important to the development of focussing hard X-ray telescopes that function up to 100 keV. The activities of the current year include extending the comparison between sputtered amorphous carbon and evaporated gold to include sputtered as well as evaporated gold. The figure of merit being the smoothness of the replica which has a direct effect on the specular reflectivity. These results were obtained with epoxy replication, but they should be applicable to electroformed nickel, the process we expect to use for the ultimate replicated optics.

  10. Apparatus and process for deposition of hard carbon films

    DOEpatents

    Nyaiesh, Ali R.; Garwin, Edward L.

    1989-01-03

    A process and an apparatus for depositing thin, amorphous carbon films having extreme hardness on a substrate is described. An enclosed chamber maintained at less than atmospheric pressure houses the substrate and plasma producing elements. A first electrode is comprised of a cavity enclosed within an RF coil which excites the plasma. A substrate located on a second electrode is excited by radio frequency power applied to the substrate. A magnetic field confines the plasma produced by the first electrode to the area away from the walls of the chamber and focuses the plasma onto the substrate thereby yielding film deposits having higher purity and having more rapid buildup than other methods of the prior art.

  11. Microstructure of Thin Films

    DTIC Science & Technology

    1990-02-07

    optical properties ." (Final text in preparation). John Lehan, "Microstructural analysis of thin films by Rutherford Backscattering...correlation of optical properties and micro- Ion assisted deposition (IAD) is known to produce structure of IAD thin films with ion beam parameters thin films ...1.5-eV interband absorption. P (eV) R (%) P (, -V) R %) Optical properties of metal thin films in the spectral 0 98.3 0 88.8 range of

  12. New approaches to hard bubble suppression

    NASA Technical Reports Server (NTRS)

    Henry, R. D.; Besser, P. J.; Warren, R. G.; Whitcomb, E. C.

    1973-01-01

    Description of a new double-layer method for the suppression of hard bubbles that is more versatile than previously reported suppression techniques. It is shown that it may be possible to prevent hard bubble generation without recourse to exchange coupling of multilayer films.

  13. Hard Spring Wheat Technical Committee 2016 Crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven experimental lines of hard spring wheat were grown at up to five locations in 2016 and evaluated for kernel, milling, and bread baking quality against the check variety Glenn. Wheat samples were submitted through the Wheat Quality Council and processed and milled at the USDA-ARS Hard Red Spri...

  14. "Hard Science" for Gifted 1st Graders

    ERIC Educational Resources Information Center

    DeGennaro, April

    2006-01-01

    "Hard Science" is designed to teach 1st grade gifted students accurate and high level science concepts. It is based upon their experience of the world and attempts to build a foundation for continued love and enjoyment of science. "Hard Science" provides field experiences and opportunities for hands-on discovery working beside experts in the field…

  15. Hard X-ray mirrors for Nuclear Security

    SciTech Connect

    Descalle, M. A.; Brejnholt, N.; Hill, R.; Decker, T.; Alameda, J.; Soufli, R.; Pivovaroff, M.; Pardini, T.

    2016-01-07

    Research performed under this LDRD aimed to demonstrate the ability to detect and measure hard X-ray emissions using multilayer X-ray reflective optics above 400 keV, to enable the development of inexpensive and high-accuracy mirror substrates, and to investigate applications of hard X-ray mirrors of interest to the nuclear security community. Experiments conducted at the European Synchrotron Radiation Facility demonstrated hard X-ray mirror reflectivity up to 650 keV for the first time. Hard X-ray optics substrates must have surface roughness under 3 to 4 Angstrom rms, and three materials were evaluated as potential substrates: polycarbonates, thin Schott glass and a new type of flexible glass called Willow Glass®. Chemical smoothing and thermal heating of the surface of polycarbonate samples, which are inexpensive but have poor intrinsic surface characteristics, did not yield acceptable surface roughness. D263 Schott glass was used for the focusing optics of the NASA NuSTAR telescope. The required specialized hardware and process were costly and motivated experiments with a modified non-contact slumping technique. The surface roughness of the glass was preserved and the process yielded cylindrical shells with good net shape pointing to the potential advantage of this technique. Finally, measured surface roughness of 200 and 130 μm thick Willow Glass sheets was between 2 and 2.5 A rms. Additional results of flexibility tests and multilayer deposition campaigns indicated it is a promising substrate for hard X-ray optics. The detection of U and Pu characteristics X-ray lines and gamma emission lines in a high background environment was identified as an area for which X-ray mirrors could have an impact and where focusing optics could help reduce signal to noise ratio by focusing signal onto a smaller detector. Hence the first one twelvetant of a Wolter I focusing optics for the 90 to 140 keV energy range based on aperiodic multilayer coating was designed. Finally

  16. Hardness methods for testing maize kernels.

    PubMed

    Fox, Glen; Manley, Marena

    2009-07-08

    Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect

  17. Magnetic Yoking and Tunable Interactions in FePt-Based Hard/Soft Bilayers

    PubMed Central

    Gilbert, Dustin A.; Liao, Jung-Wei; Kirby, Brian J.; Winklhofer, Michael; Lai, Chih-Huang; Liu, Kai

    2016-01-01

    Magnetic interactions in magnetic nanostructures are critical to nanomagnetic and spintronic explorations. Here we demonstrate an extremely sensitive magnetic yoking effect and tunable interactions in FePt based hard/soft bilayers mediated by the soft layer. Below the exchange length, a thin soft layer strongly exchange couples to the perpendicular moments of the hard layer; above the exchange length, just a few nanometers thicker, the soft layer moments turn in-plane and act to yoke the dipolar fields from the adjacent hard layer perpendicular domains. The evolution from exchange to dipolar-dominated interactions is experimentally captured by first-order reversal curves, the ΔM method, and polarized neutron reflectometry, and confirmed by micromagnetic simulations. These findings demonstrate an effective yoking approach to design and control magnetic interactions in wide varieties of magnetic nanostructures and devices. PMID:27604428

  18. Nanoindentation of a hard ceramic coating formed on a soft substrate

    NASA Astrophysics Data System (ADS)

    Surmeneva, M. A.; Surmenev, R. A.; Tyurin, A. I.; Pirozhkova, T. S.; Shuvarin, I. A.

    2016-09-01

    The hardness and Young's modulus of the thin hydroxyapatite-based coatings deposited by RF magnetron sputtering onto magnesium alloy, titanium, and steel substrates are studied. As the penetration depth increases, the hardness and Young's modulus of these coatings are found to tend toward the values that are characteristic of the substrates. It is shown that the difference between the values of hardness and Young's modulus at small penetration depths ( h < 80-100 nm) can be caused by the difference between the physicomechanical properties inside the coatings and that this difference at large penetration depths ( h > 100 nm) can be induced by an additional effect of the strength properties of the substrate material.

  19. Magnetic Yoking and Tunable Interactions in FePt-Based Hard/Soft Bilayers

    NASA Astrophysics Data System (ADS)

    Gilbert, Dustin A.; Liao, Jung-Wei; Kirby, Brian J.; Winklhofer, Michael; Lai, Chih-Huang; Liu, Kai

    2016-09-01

    Magnetic interactions in magnetic nanostructures are critical to nanomagnetic and spintronic explorations. Here we demonstrate an extremely sensitive magnetic yoking effect and tunable interactions in FePt based hard/soft bilayers mediated by the soft layer. Below the exchange length, a thin soft layer strongly exchange couples to the perpendicular moments of the hard layer; above the exchange length, just a few nanometers thicker, the soft layer moments turn in-plane and act to yoke the dipolar fields from the adjacent hard layer perpendicular domains. The evolution from exchange to dipolar-dominated interactions is experimentally captured by first-order reversal curves, the ΔM method, and polarized neutron reflectometry, and confirmed by micromagnetic simulations. These findings demonstrate an effective yoking approach to design and control magnetic interactions in wide varieties of magnetic nanostructures and devices.

  20. Hardness Evolution of Gamma-Irradiated Polyoxymethylene

    NASA Astrophysics Data System (ADS)

    Hung, Chuan-Hao; Harmon, Julie P.; Lee, Sanboh

    2016-12-01

    This study focuses on analyzing hardness evolution in gamma-irradiated polyoxymethylene (POM) exposed to elevated temperatures after irradiation. Hardness increases with increasing annealing temperature and time, but decreases with increasing gamma ray dose. Hardness changes are attributed to defects generated in the microstructure and molecular structure. Gamma irradiation causes a decrease in the glass transition temperature, melting point, and extent of crystallinity. The kinetics of defects resulting in hardness changes follow a first-order structure relaxation. The rate constant adheres to an Arrhenius equation, and the corresponding activation energy decreases with increasing dose due to chain scission during gamma irradiation. The structure relaxation of POM has a lower energy barrier in crystalline regions than in amorphous ones. The hardness evolution in POM is an endothermic process due to the semi-crystalline nature of this polymer.

  1. Thermal spray coatings replace hard chrome

    SciTech Connect

    Schroeder, M.; Unger, R.

    1997-08-01

    Hard chrome plating provides good wear and erosion resistance, as well as good corrosion protection and fine surface finishes. Until a few years ago, it could also be applied at a reasonable cost. However, because of the many environmental and financial sanctions that have been imposed on the process over the past several years, cost has been on a consistent upward trend, and is projected to continue to escalate. Therefore, it is very important to find a coating or a process that offers the same characteristics as hard chrome plating, but without the consequent risks. This article lists the benefits and limitations of hard chrome plating, and describes the performance of two thermal spray coatings (tungsten carbide and chromium carbide) that compared favorably with hard chrome plating in a series of tests. It also lists three criteria to determine whether plasma spray or hard chrome plating should be selected.

  2. Evaluating mechanical properties of thin layers using nanoindentation and finite-element modeling: Implanted metals and deposited layers

    SciTech Connect

    Knapp, J.A.; Follstaedt, D.M.; Barbour, J.C.

    1996-12-31

    We present a methodology based on finite-element modeling of nanoindentation data to extract reliable and accurate mechanical properties from thin, hard films and surface-modified layers on softer substrates. The method deduces the yield stress, Young`s modulus, and hardness from indentations as deep as 50% of the layer thickness.

  3. Pyrolyzed thin film carbon

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  4. Nanoindentation of GaSe thin films

    PubMed Central

    2012-01-01

    The structural and nanomechanical properties of GaSe thin films were investigated by means of X-ray diffraction (XRD) and nanoindentation techniques. The GaSe thin films were deposited on Si(111) substrates by pulsed laser deposition. XRD patterns reveal only the pure (000 l)-oriented reflections originating from the hexagonal GaSe phase and no trace of any impurity or additional phases. Nanoindentation results exhibit discontinuities (so-called multiple ‘pop-in’ events) in the loading segments of the load–displacement curves, and the continuous stiffness measurements indicate that the hardness and Young’s modulus of the hexagonal GaSe films are 1.8 ± 0.2 and 65.8 ± 5.6 GPa, respectively. PMID:22804961

  5. A study on the ESD damage of a silicon oxy-nitride hard mask on the chromium surface of PSM blank

    NASA Astrophysics Data System (ADS)

    Moon, Songbae; Kim, Heebom; Shin, Inkyun; Jeon, Chanuk

    2013-09-01

    A thin silicon oxy-nitride hard mask on the PSM blank is needed for the feature patterning with the size smaller than 70 nm. It is a good material for hard mask. However, the electrical property of silicon oxy-nitride with the thickness smaller than 10 nm causes the chromium surface damage during the mask processes. From the measurement of the surface damage, we figure out that the chromium surface damage is originated from the charging and the dielectric breakdown phenomena. In our present work, two types of silicon oxy-nitride film with the thicknesses of 5 nm and 12 nm are tested for verifying optimal mask fabrication processes. We find that the occurrence of ESD damage is related to the thickness of silicon oxy-nitride hard mask and mask fabrication process conditions. The optimal fabrication process condition for silicon oxy-nitride thin film hard mask, in which break-down never occurs, is discussed.

  6. Automated radiation hard ASIC design tool

    NASA Technical Reports Server (NTRS)

    White, Mike; Bartholet, Bill; Baze, Mark

    1993-01-01

    A commercial based, foundry independent, compiler design tool (ChipCrafter) with custom radiation hardened library cells is described. A unique analysis approach allows low hardness risk for Application Specific IC's (ASIC's). Accomplishments, radiation test results, and applications are described.

  7. 21 CFR 133.150 - Hard cheeses.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... action of harmless lactic-acid-producing bacteria, with or without other harmless flavor-producing... minutes, or for a time and at a temperature equivalent thereto in phosphatase destruction. A hard...

  8. Macroindentation hardness measurement-Modernization and applications.

    PubMed

    Patel, Sarsvat; Sun, Changquan Calvin

    2016-06-15

    In this study, we first developed a modernized indentation technique for measuring tablet hardness. This technique is featured by rapid digital image capture, using a calibrated light microscope, and precise area-determination. We then systematically studied effects of key experimental parameters, including indentation force, speed, and holding time, on measured hardness of a very soft material, hydroxypropyl cellulose, and a very hard material, dibasic calcium phosphate, to cover a wide range of material properties. Based on the results, a holding period of 3min at the peak indentation load is recommended to minimize the effect of testing speed on H. Using this method, we show that an exponential decay function well describes the relationship between tablet hardness and porosity for seven commonly used pharmaceutical powders investigated in this work. We propose that H and H at zero porosity may be used to quantify the tablet deformability and powder plasticity, respectively.

  9. Electronic Teaching: Hard Disks and Networks.

    ERIC Educational Resources Information Center

    Howe, Samuel F.

    1984-01-01

    Describes floppy-disk and hard-disk based networks, electronic systems linking microcomputers together for the purpose of sharing peripheral devices, and presents points to remember when shopping for a network. (MBR)

  10. Novel hard compositions and methods of preparation

    DOEpatents

    Sheinberg, H.

    1981-02-03

    Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value.

  11. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., if any is present, for any seed required to be labeled as to the percentage of germination, and the percentage of hard seed shall not be included as part of the germination percentage. [24 FR 3953, May...

  12. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., if any is present, for any seed required to be labeled as to the percentage of germination, and the percentage of hard seed shall not be included as part of the germination percentage. [24 FR 3953, May...

  13. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... any is present, for any seed required to be labeled as to the percentage of germination, and the percentage of hard seed shall not be included as part of the germination percentage. [32 FR 12779, Sept....

  14. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... any is present, for any seed required to be labeled as to the percentage of germination, and the percentage of hard seed shall not be included as part of the germination percentage. [32 FR 12779, Sept....

  15. Hard Suit With Adjustable Torso Length

    NASA Technical Reports Server (NTRS)

    Vykukal, Hubert C.

    1987-01-01

    Torso sizing rings allow single suit to fit variety of people. Sizing rings inserted between coupling rings of torso portion of hard suit. Number of rings chosen to fit torso length of suit to that of wearer. Rings mate with, and seal to, coupling rings and to each other. New adjustable-size concept with cost-saving feature applied to other suits not entirely constructed of "hard" materials, such as chemical defense suits and suits for industrial-hazard cleanup.

  16. A Novel Approach to Hardness Testing

    NASA Technical Reports Server (NTRS)

    Spiegel, F. Xavier; West, Harvey A.

    1996-01-01

    This paper gives a description of the application of a simple rebound time measuring device and relates the determination of relative hardness of a variety of common engineering metals. A relation between rebound time and hardness will be sought. The effect of geometry and surface condition will also be discussed in order to acquaint the student with the problems associated with this type of method.

  17. Laser Ablatin of Dental Hard Tissue

    SciTech Connect

    Seka, W.; Rechmann, P.; Featherstone, J.D.B.; Fried, D.

    2007-07-31

    This paper discusses ablation of dental hard tissue using pulsed lasers. It focuses particularly on the relevant tissue and laser parameters and some of the basic ablation processes that are likely to occur. The importance of interstitial water and its phase transitions is discussed in some detail along with the ablation processes that may or may not directly involve water. The interplay between tissue parameters and laser parameters in the outcome of the removal of dental hard tissue is discussed in detail.

  18. Hard x ray highlights of AR 5395

    NASA Technical Reports Server (NTRS)

    Schwartz, R. A.; Dennis, Brian R.

    1989-01-01

    Active Region 5395 produced an exceptional series of hard x ray bursts notable for their frequency, intensity, and impulsivity. Over the two weeks from March 6 to 19, 447 hard x ray flares were observed by the Hard X Ray Burst Spectrometer on Solar Maximum Mission (HXRBS/SMM), a rate of approx. 35 per day which exceeded the previous high by more than 50 percent. During one 5 day stretch, more than 250 flares were detected, also a new high. The three largest GOES X-flares were observed by HXRBS and had hard x ray rates over 100,000 s(exp -1) compared with only ten flares above 100,000(exp -1) during the previous nine years of the mission. An ongoing effort for the HXRBS group has been the correlated analysis of hard x ray data with flare data at other wavelengths with the most recent emphasis on those measurements with spatial information. During a series of bursts from AR 5395 at 1644 to 1648 UT on 12 March 1989, simultaneous observations were made by HXRBS and UVSP (Ultra Violet Spectrometer Polarimeter) on SMM, the two-element Owens Valley Radio Observatory (OVRO) interferometric array, and R. Canfield's H-alpha Echelle spectrograph at the National Solar Observatory at Sacramento Peak. The data show strong correlations in the hard x ray, microwave, and UV lightcurves. This event will be the subject of a combined analysis.

  19. Co-analysis of Solar Microwave and Hard X-Ray Spectral Evolutions. I. In Two Frequency or Energy Ranges

    NASA Astrophysics Data System (ADS)

    Song, Qiwu; Huang, Guangli; Nakajima, Hiroshi

    2011-06-01

    Solar microwave and hard X-ray spectral evolutions are co-analyzed in the 2000 June 10 and 2002 April 10 flares, and are simultaneously observed by the Owens-Valley Solar Array in the microwave band and by Yohkoh/Hard X-ray Telescope or RHESSI in the hard X-ray band, with multiple subpeaks in their light curves. The microwave and hard X-ray spectra are fitted by a power law in two frequency ranges of the optical thin part and two photon energy ranges, respectively. Similar to an earlier event in Shao & Huang, the well-known soft-hard-soft pattern of the lower energy range changed to the hard-soft-hard (HSH) pattern of the higher energy range during the spectral evolution of each subpeak in both hard X-ray flares. This energy dependence is actually supported by a positive correlation between the overall light curves and spectral evolution in the lower energy range, while it becomes an anti-correlation in the higher energy range. Regarding microwave data, the HSH pattern appears in the spectral evolution of each subpeak in the lower frequency range, which is somewhat similar to Huang & Nakajima. However, it returns back to the well-known pattern of soft-hard-harder for the overall spectral evolution in the higher frequency range of both events. This frequency dependence is confirmed by an anti-correlation between the overall light curves and spectral evolution in the lower frequency range, but it becomes a positive correlation in the higher frequency range. The possible mechanisms are discussed, respectively, for reasons why hard X-ray and microwave spectral evolutions have different patterns in different energy and frequency intervals.

  20. Thin film interference of colloidal thin films.

    PubMed

    Cong, Hailin; Cao, Weixiao

    2004-09-14

    A stairlike colloidal crystal thin film composed of poly(styrene-methyl methacrylate-acrylic acid) (P(St-MMA-AA)) monodispersed colloids was fabricated on an inclined silicon substrate. Different bright colors were observed on the various parts of the film with different layers as white light irradiated perpendicularly on it. The relationship between the colors and layers of the film was investigated and discussed according to the principle of thin film interference. On the basis of the phenomenon of thin film interference, a one-layer colloidal film having uniform color was researched and it would display diverse colors before and after swollen by styrene (St). A circular stairlike colloidal film was achieved to mimic the colors of the peacock tail feather.

  1. Mechanics of Thin Films

    DTIC Science & Technology

    1992-02-06

    S. Hwang, Thermal conductivity of thin films: measurement and microstructural effects, in Thin- film heat transfer, properties and processing, ed...thermal, electrical, optical and magnetic properties . As typical examples we mention microelectronics, optical coatings and multilayers for use in optical...interplay between mechanical properties (elastic moduli), thermal properties (thermal conductivity, thermal expansion coefficient), and optical

  2. Hard error generation by neutron irradiation

    SciTech Connect

    Browning, J.S.; Gover, J.E.; Wrobel, T.F.; Hass, K.J.; Nasby, R.D.; Simpson, R.L.; Posey, L.D.; Boos, R.E.; Block, R.C.

    1987-01-01

    We have observed that neutron-induced fission of uranium contaminants present in alumina ceramic package lids results in the release of fission fragments that can cause hard errors in metal nitride-oxidenonvolatile RAMs (MNOS NVRAMs). Hard error generation requires the simultaneous presence of (1) a fission fragment with a linear energy transfer (LET) greater than 20 MeV/mg/cm/sup 2/ moving at an angle of 30/sup 0/ or less from the electric field in the high-field, gate region of the memory transistor and (2) a WRITE or ERASE voltage on the oxide-nitride transistor gate. In reactor experiments, we observe these hard errors when a ceramic lid is used on both MNOS NVRAMs and polysilicon-nitride-oxide-semiconductor (SNOS) capacitors, but hard errors are not observed when a gold-plated kovar lid is used on the package containing these die. We have mapped the tracks of the fission fragments released from the ceramic lids with a mica track detector and used a Monte Carlo model of fission fragment transport through the ceramic lid to measure the concentration of uranium present in the lids. Our concentration measurements are in excellent agreement with others' measurements of uranium concentration in ceramic lids. Our Monte Carlo analyses also agree closely with our measurements of hard error probability in MNOS NVRAMs. 15 refs., 13 figs., 8 tabs.

  3. Haptic search for hard and soft spheres.

    PubMed

    van Polanen, Vonne; Bergmann Tiest, Wouter M; Kappers, Astrid M L

    2012-01-01

    In this study the saliency of hardness and softness were investigated in an active haptic search task. Two experiments were performed to explore these properties in different contexts. In Experiment 1, blindfolded participants had to grasp a bundle of spheres and determine the presence of a hard target among soft distractors or vice versa. If the difference in compliance between target and distractors was small, reaction times increased with the number of items for both features; a serial strategy was found to be used. When the difference in compliance was large, the reaction times were independent of the number of items, indicating a parallel strategy. In Experiment 2, blindfolded participants pressed their hand on a display filled with hard and soft items. In the search for a soft target, increasing reaction times with the number of items were found, but the location of target and distractors appeared to have a large influence on the search difficulty. In the search for a hard target, reaction times did not depend on the number of items. In sum, this showed that both hardness and softness are salient features.

  4. Novel hard compositions and methods of preparation

    DOEpatents

    Sheinberg, Haskell

    1983-08-23

    Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value. Photomicrographs show that the shapes of the grains of the alloy mixture with which the minor amount of carbide (or carbide-formers) is mixed are radically altered from large, rounded to small, very angular by the addition of the carbide. Superiority of one of these hard compositions of matter over cobalt-bonded tungsten carbide for ultra-high pressure anvil applications was demonstrated.

  5. Novel hard compositions and methods of preparation

    DOEpatents

    Sheinberg, H.

    1983-08-23

    Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value. Photomicrographs show that the shapes of the grains of the alloy mixture with which the minor amount of carbide (or carbide-formers) is mixed are radically altered from large, rounded to small, very angular by the addition of the carbide. Superiority of one of these hard compositions of matter over cobalt-bonded tungsten carbide for ultra-high pressure anvil applications was demonstrated. 3 figs.

  6. Hard QCD rescattering in few nucleon systems

    NASA Astrophysics Data System (ADS)

    Maheswari, Dhiraj; Sargsian, Misak

    2017-01-01

    The theoretical framework of hard QCD rescattering mechanism (HRM) is extended to calculate the high energy γ3 He -> pd reaction at 900 center of mass angle. In HRM model , the incoming high energy photon strikes a quark from one of the nucleons in the target which subsequently undergoes hard rescattering with the quarks from the other nucleons generating hard two-body baryonic system in the final state of the reaction. Based on the HRM, a parameter free expression for the differential cross section for the reaction is derived, expressed through the 3 He -> pd transition spectral function, hard pd -> pd elastic scattering cross section and the effective charge of the quarks being interchanged in the hard rescattering process. The numerical estimates obtained from this expression for the differential cross section are in a good agreement with the data recently obtained at the Jefferson Lab experiment, showing the energy scaling of cross section with an exponent of s-17, also consistent with the quark counting rule. The angular and energy dependences of the cross section are also predicted within HRM which are in good agreement with the preliminary data of these distributions. Research is supported by the US Department of Energy.

  7. ORMOSIL thin films: tuning mechanical properties via a nanochemistry approach.

    PubMed

    Palmisano, Giovanni; Le Bourhis, Eric; Ciriminna, Rosaria; Tranchida, Davide; Pagliaro, Mario

    2006-12-19

    The mechanical properties (hardness and elastic modulus) of organically modified silicate thin films can be finely tuned by varying the degree of alkylation and thus the fraction of six- and four-membered siloxane rings in the organosilica matrix. This opens the way to large tunability of parameters that are of crucial practical importance for films that are finding increasing application in numerous fields ranging from microelectronics to chemical sensing.

  8. Microwave and hard X-ray emissions during the impulsive phase of solar flares: Nonthermal electron spectrum and time delay

    NASA Technical Reports Server (NTRS)

    Gu, Ye-Ming; Li, Chung-Sheng

    1986-01-01

    On the basis of the summing-up and analysis of the observations and theories about the impulsive microwave and hard X-ray bursts, the correlations between these two kinds of emissions were investigated. It is shown that it is only possible to explain the optically-thin microwave spectrum and its relations with the hard X-ray spectrum by means of the nonthermal source model. A simple nonthermal trap model in the mildly-relativistic case can consistently explain the main characteristics of the spectrum and the relative time delays.

  9. Optical thin film devices

    NASA Astrophysics Data System (ADS)

    Mao, Shuzheng

    1991-11-01

    Thin film devices are applied to almost all modern scientific instruments, and these devices, especially optical thin film devices, play an essential role in the performances of the instruments, therefore, they are attracting more and more attention. Now there are numerous kinds of thin film devices and their applications are very diversified. The 300-page book, 'Thin Film Device and Applications,' by Prof. K. L. Chopra gives some general ideas, and my paper also outlines the designs, fabrication, and applications of some optical thin film devices made in my laboratory. Optical thin film devices have been greatly developed in the recent decades. Prof. A. Thelan has given a number of papers on the theory and techniques, Prof. H. A. Macleod's book, 'Thin Film Optical Filters,' has concisely concluded the important concepts of optical thin film devices, and Prof. J. A. Dobrowobski has proposed many successful designs for optical thin film devices. Recently, fully-automatic plants make it easier to produce thin film devices with various spectrum requirements, and some companies, such as Balzers, Leybold AG, Satis Vacuum AG, etc., have manufactured such kinds of coating plants for research or mass-production, and the successful example is the production of multilayer antireflection coatings with high stability and reproducibility. Therefore, it could be said that the design of optical thin film devices and coating plants is quite mature. However, we cannot expect that every problem has been solved, the R&D work still continues, the competition still continues, and new design concepts, new techniques, and new film materials are continually developed. Meanwhile, the high-price of fully-automatic coating plants makes unpopular, and automatic design of coating stacks is only the technique for optimizing the manual design according to the physical concepts and experience, in addition, not only the optical system, but also working environment should be taken into account when

  10. Research in the Hard Sciences, and in Very Hard "Softer" Domains

    ERIC Educational Resources Information Center

    Phillips, D. C.

    2014-01-01

    The author of this commentary argues that physical scientists are attempting to advance knowledge in the so-called hard sciences, whereas education researchers are laboring to increase knowledge and understanding in an "extremely hard" but softer domain. Drawing on the work of Popper and Dewey, this commentary highlights the relative…

  11. Hard Water and Soft Soap: Dependence of Soap Performance on Water Hardness

    ERIC Educational Resources Information Center

    Osorio, Viktoria K. L.; de Oliveira, Wanda; El Seoud, Omar A.; Cotton, Wyatt; Easdon, Jerry

    2005-01-01

    The demonstration of the performance of soap in different aqueous solutions, which is due to water hardness and soap formulation, is described. The demonstrations use safe, inexpensive reagents and simple glassware and equipment, introduce important everyday topics, stimulates the students to consider the wider consequences of water hardness and…

  12. "We Can Get Everything We Want if We Try Hard": Young People, Celebrity, Hard Work

    ERIC Educational Resources Information Center

    Mendick, Heather; Allen, Kim; Harvey, Laura

    2015-01-01

    Drawing on 24 group interviews on celebrity with 148 students aged 14-17 across six schools, we show that "hard work" is valued by young people in England. We argue that we should not simply celebrate this investment in hard work. While it opens up successful subjectivities to previously excluded groups, it reproduces neoliberal…

  13. Saltwater and hard water bentonite mud

    SciTech Connect

    Pabley, A. S.

    1985-02-19

    A seawater/saltwater or hard water bentonite mud for use in drilling, and process for preparing same, comprising sequentially adding to seawater, to saltwater of a chloride concentration up to saturation, or hard water: a caustic agent; a filtration control agent; and bentonite. The resultant drilling mud meets API standards for viscosity and water loss, and is stable after aging and at tempertures in excess of 100/sup 0/ c. In another embodiment, the additives are premixed as dry ingredients and hydrated with seawater, saltwater or hard water. Unlike other bentonite drilling muds, the muds of this invention require no fresh water in their preparation, which makes them particularly useful at off-shore and remote on-shore drilling locations. The muds of this invention using bentonite further require less clay than known saltwater muds made with attapulgite, and provides superior filtration control, viscosity and stability.

  14. Potential Health Impacts of Hard Water

    PubMed Central

    Sengupta, Pallav

    2013-01-01

    In the past five decades or so evidence has been accumulating about an environmental factor, which appears to be influencing mortality, in particular, cardiovascular mortality, and this is the hardness of the drinking water. In addition, several epidemiological investigations have demonstrated the relation between risk for cardiovascular disease, growth retardation, reproductive failure, and other health problems and hardness of drinking water or its content of magnesium and calcium. In addition, the acidity of the water influences the reabsorption of calcium and magnesium in the renal tubule. Not only, calcium and magnesium, but other constituents also affect different health aspects. Thus, the present review attempts to explore the health effects of hard water and its constituents. PMID:24049611

  15. Hard template synthesis of metal nanowires

    PubMed Central

    Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

    2014-01-01

    Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance, and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed. PMID:25453031

  16. Hard-Core Unemployment: A Selected, Annotated Bibliography.

    ERIC Educational Resources Information Center

    Cameron, Colin, Comp.; Menon, Anila Bhatt, Comp.

    This annotated bibliography contains references to various films, articles, and books on the subject of hard-core unemployment, and is divided into the following sections: (1) The Sociology of the Hard-Core Milieu, (2) Training Programs, (3) Business and the Hard-Core, (4) Citations of Miscellaneous References on Hard-Core Unemployment, (5)…

  17. Flexibility of hard gas permeable contact lenses.

    PubMed

    Stevenson, R W

    1988-11-01

    Gas permeable (GP) lenses can flex on some eyes producing unpredictable clinical results. A method of measuring the flexibility of hard GP materials has been developed and shown to be repeatable. Materials in the form of flats rather than lenses were used. Differences between materials were found and in general a linear relation was shown to exist between maximum flexing and quoted oxygen permeability (r = 0.78, p less than 0.05). It is recommended that flexibility be measured and reported in the data presented with all new GP polymers. The term "hard" rather than "rigid" in describing GP lenses is suggested.

  18. Novel Aspects of Hard Diffraction in QCD

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2005-12-14

    Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, and nuclear shadowing and antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency.

  19. Analysis of coronal and chromospheric hard X-ray sources in an eruptive solar flare

    NASA Astrophysics Data System (ADS)

    Zimovets, Ivan; Golovin, Dmitry; Livshits, Moisey; Vybornov, Vadim; Sadykov, Viacheslav; Mitrofanov, Igor

    We have analyzed hard X-ray emission of an eruptive solar flare on 3 November 2010. The entire flare region was observed by the STEREO-B spacecraft. This gave us an information that chromospheric footpoints of flare magnetic loops were behind the east solar limb for an earth observer. Hard X-ray emission from the entire flare region was detected by the High Energy Neutron Detector (HEND) onboard the 2001 Mars Odyssey spacecraft while hard X-rays from the coronal part of the flare region were detected by the RHESSI. This rare situation has allowed us to investigate both coronal and chromospheric sources of hard X-ray emission separately. Flare impulsive phase was accompanied by eruption of a magnetic flux rope and formation of a plasmoid detected by the AIA/SDO in the EUV range. Two coronal hard X-ray sources (S_{1} and S_{2}) were detected by the RHESSI. The upper source S_{1} coincided with the plasmoid and the lower source S_{2} was near the tops of the underlying flare loops that is in accordance with the standard model of eruptive flares. Imaging spectroscopy with the RHESSI has allowed to measure energetic spectra of hard X-ray emission from the S_{1} and S_{2} sources. At the impulsive phase peak they have power-law shape above ≈ 15 keV with spectral slopes gamma_{S_{1}}=3.46 ± 1.58 and gamma_{S_{2}}=4.64 ± 0.12. Subtracting spatially integrated spectrum of coronal hard X-ray emission measured by the RHESSI from the spectrum measured by the HEND we found spectrum of hard X-rays emitted from the footpoints of the flare loops (source S_{0}). This spectrum has a power-law shape with gamma_{S_{0}}=2.21 ± 0.57. It is shown that it is not possible to explain the measured spectra of the S_{2} and S_{0} sources in frames of the thin and thick target models respectively if we assume that electrons were accelerated in the energy release site situated below the plasmoid and above the flare loops as suggested by the standard flare model. To resolve the contradiction

  20. van der Waals-Tonks-type equations of state for hard-disk and hard-sphere fluids.

    PubMed

    Wang, Xian Zhi

    2002-09-01

    Using the known virial coefficients of hard-disk and hard-sphere fluids, we develop van der Waals-Tonks-type equations of state for hard-disk and hard-sphere fluids. In the low-density fluid regime, these equations of state are in good agreement with the simulation results and the existing equations of state.

  1. Electrochemical thinning of silicon

    DOEpatents

    Medernach, J.W.

    1994-01-11

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR). 14 figures.

  2. Electrochemical thinning of silicon

    DOEpatents

    Medernach, John W.

    1994-01-01

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR).

  3. Biomimetic thin film synthesis

    SciTech Connect

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  4. Thin film hydrogen sensor

    DOEpatents

    Cheng, Yang-Tse; Poli, Andrea A.; Meltser, Mark Alexander

    1999-01-01

    A thin film hydrogen sensor, includes: a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end.

  5. Thin film hydrogen sensor

    DOEpatents

    Cheng, Y.T.; Poli, A.A.; Meltser, M.A.

    1999-03-23

    A thin film hydrogen sensor includes a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end. 5 figs.

  6. Effect of substrate hardness on the deformation behavior of subsequently incident particles in cold spraying

    NASA Astrophysics Data System (ADS)

    Yin, Shuo; Wang, Xiao-fang; Li, W. Y.; Jie, Hong-en

    2011-06-01

    A systematic finite element analysis (FEA) on the subsequently incident particles which refer to the particles depositing after the formation of the first layer coating is conducted in this study to clarify the bonding mechanism inside the cold sprayed coating. A simplified particle impact model is proposed and the simulated results based on this model demonstrate that substrate hardness exerts some effects on the deformation behavior of the subsequently incident particles. Hard substrate makes these particles deform intensively but using soft substrate enables them to achieve a slight deformation. At the same time, it is also found that substrate hardness plays its best role only when the formed coating is thin, as the development of the coating, the particle deformation behavior becomes more and more insensitive to the substrate hardness. The multi-particle impact simulation based on Eulerian method is also performed and reaches the same conclusion, confirming the accuracy of the simplified model. Besides, it is also found that when the velocity is increased to a hypervelocity, excessive deformation occurs in the formed coatings due to the impact of the subsequently incident particles.

  7. Raman Spectroscopy Characterization of amorphous carbon coatings for computer hard disks

    SciTech Connect

    Ager III, Joel W.

    1998-05-07

    Amorphous carbon films are used as protective coatings on magnetic media to protect the magnetic layer from wear and abrasion caused by the read/write head during hard disk drive start-up and operation. A key requirement in increasing the storage capacity and reliability of hard-disk drives is improving the performance of these coatings. This cooperative agreement used optical characterization techniques developed at LBNL to study thin-film hard disk media produced by Seagate Technology, major US hard drive manufacturer. The chief scientific goal was relating quantitatively the results of the optical characterization to the underlying chemical structure of the overcoat. In a collaboration with Seagate, LBNL, and Cambridge University, optical and electron-based characterization were used to evaluate the chemical structure of overcoats. The sp3 fraction of the sputtered amorphous carbon films was measured quantitatively for the first time and related to the optical spectroscopy results. This work and other selected aspects of the research performed under the agreement were presented at technical meetings and published in the open literature. The chief technical goal was designing manufacturing processes for the protective carbon overcoat for use in new generations of Seagate disk drives. To this end, joint research carried out under this agreement enabled Seagate to speed development of new coatings which are currently being used in the production of disk media in Seagate's disk-media manufacturing plants in Fremont, CA.

  8. Remember Hard But Think Softly: Metaphorical Effects of Hardness/Softness on Cognitive Functions.

    PubMed

    Xie, Jiushu; Lu, Zhi; Wang, Ruiming; Cai, Zhenguang G

    2016-01-01

    Previous studies have found that bodily stimulation, such as hardness biases social judgment and evaluation via metaphorical association; however, it remains unclear whether bodily stimulation also affects cognitive functions, such as memory and creativity. The current study used metaphorical associations between "hard" and "rigid" and between "soft" and "flexible" in Chinese, to investigate whether the experience of hardness affects cognitive functions whose performance depends prospectively on rigidity (memory) and flexibility (creativity). In Experiment 1, we found that Chinese-speaking participants performed better at recalling previously memorized words while sitting on a hard-surface stool (the hard condition) than a cushioned one (the soft condition). In Experiment 2, participants sitting on a cushioned stool outperformed those sitting on a hard-surface stool on a Chinese riddle task, which required creative/flexible thinking, but not on an analogical reasoning task, which required both rigid and flexible thinking. The results suggest the hardness experience affects cognitive functions that are metaphorically associated with rigidity or flexibility. They support the embodiment proposition that cognitive functions and representations can be grounded in bodily states via metaphorical associations.

  9. A new technique to prepare hard fruits and seeds for anatomical studies1

    PubMed Central

    Benedict, John C.

    2015-01-01

    Premise of the study: A novel preparation technique was developed to examine fruits and seeds of plants with exceptionally hard or brittle tissues that are very difficult to prepare using standard histological techniques. Methods and Results: The method introduced here was modified from a technique employed on fossil material and has been adapted for use on fruits and seeds of extant plants. A variety of fruits and seeds have been prepared with great success, and the technique will be useful for any excessively hard fruits or seeds that are not able to be prepared using traditional embedding or sectioning methods. Conclusions: When compared to existing techniques for obtaining anatomical features of fruits and seeds, the protocol described here has the potential to create high-quality thin sections of materials that are not able to be sectioned using traditional histological techniques, which can be produced quickly and without the need for harmful chemicals. PMID:26504684

  10. Radiation hardness by design for mixed signal infrared readout circuit applications

    NASA Astrophysics Data System (ADS)

    Gaalema, Stephen; Gates, James; Dobyns, David; Pauls, Greg; Wall, Bruce

    2013-09-01

    Readout integrated circuits (ROICs) to support space-based infrared detection applications often have severe radiation tolerance requirements. Radiation hardness-by-design (RHBD) significantly enhances the radiation tolerance of commercially available CMOS and custom radiation hardened fabrication techniques are not required. The combination of application specific design techniques, enclosed gate architecture nFETs and intrinsic thin oxide radiation hardness of 180 nm process node commercial CMOS allows realization of high performance mixed signal circuits. Black Forest Engineering has used RHBD techniques to develop ROICs with integrated A/D conversion that operate over a wide range of temperatures (40K-300K) to support infrared detection. ROIC radiation tolerance capability for 256x256 LWIR area arrays and 1x128 thermopile linear arrays is presented. The use of 130 nm CMOS for future ROIC RHBD applications is discussed.

  11. Sustaining Transformation: "Resiliency in Hard Times"

    ERIC Educational Resources Information Center

    Guarasci, Richard; Lieberman, Devorah

    2009-01-01

    The strategic, systemic, and encompassing evolution of a college or university spans a number of years, and the vagaries of economic cycles inevitably catch transforming institutions in mid-voyage. "Sustaining Transformation: Resiliency in Hard Times" presents a study of Wagner College as it moves into its second decade of purposeful…

  12. Hard error generation by thermal neutrons

    SciTech Connect

    Browning, J.S.; Gover, J.E.; Wrobel, T.F.; Hass, K.J.; Nasby, R.D.; Simpson, R.L.; Posey, L.D.; Block, R.C.

    1987-01-01

    The generation of hard errors in MNOS dielectric structures has been observed at thermal neutron fluence levels of 3.6 x 10/sup 13/ n/cm/sup 2/. Fission fragments from neutron induced fission of /sup 235/U contamination in ceramic lids have been shown to be responsible.

  13. Registration of 'Advance' Hard Red Spring Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grower and end-user acceptance of new hard red spring wheat (HRSW; Triticum aestivum L.) cultivars is largely contingent on satisfactory agronomic performance, end-use quality potential, and disease resistance levels. Additional characteristics, such as desirable plant height, can also help to maxi...

  14. Radiation-Hardness Data For Semiconductor Devices

    NASA Technical Reports Server (NTRS)

    Price, W. E.; Nichols, D. K.; Brown, S. F.; Gauthier, M. K.; Martin, K. E.

    1984-01-01

    Document presents data on and analysis of radiation hardness of various semiconductor devices. Data specifies total-dose radiation tolerance of devices. Volume 1 of report covers diodes, bipolar transistors, field effect transistors, silicon controlled rectifiers and optical devices. Volume 2 covers integrated circuits. Volume 3 provides detailed analysis of data in volumes 1 and 2.

  15. Carry Hard ICBM basing: A technical assessment

    SciTech Connect

    Harvey, J.R.; Schaffer, A.B.; Speed, R.; Todaro, A.F.

    1989-11-15

    Carry Hard is a deceptive, multiple-aimpoint ICBM basing concept in which hardened, encapsulated missiles are shuttled among several thousand, low-cost, water-filled vertical shelters. Since most of the essential launch and operational support equipment is carried with the missile (not provided with each shelter), the overall system costs are reduced. High system hardness permits relatively close shelter spacing, which in turn allows Carry Hard to be deployed on a comparatively small piece of land (a few hundred square miles) that could be removed from public access. Controlled access to the deployment area helps in maintaining concealment of the missiles among the shelters. If concealment is successfully maintained, the system is believed to be survivable against plausible Soviet threats, regardless of whether attack-warning information is received or acted upon. Thus, Carry Hard holds high promise as a feasible, affordable, and survivable means of ICBM deployment, and a high priority should be given to developing the concept to the point that an informed decision on full-scale engineering development can be made. 33 refs., 4 figs., 5 tabs.

  16. Registration of 'Prevail' hard red spring wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grower and end-user acceptance of new Hard Red Spring Wheat (HRSW; Triticum aestivum L.) cultivars is largely contingent upon satisfactory agronomic performance, end-use quality potential, and disease resistance levels. Additional characteristics, such as desirable plant height, can also contribute...

  17. Parallel Narrative Structure in Paul Harding's "Tinkers"

    ERIC Educational Resources Information Center

    Çirakli, Mustafa Zeki

    2014-01-01

    The present paper explores the implications of parallel narrative structure in Paul Harding's "Tinkers" (2009). Besides primarily recounting the two sets of parallel narratives, "Tinkers" also comprises of seemingly unrelated fragments such as excerpts from clock repair manuals and diaries. The main stories, however, told…

  18. Hard Times: Philosophy and the Fundamentalist Imagination

    ERIC Educational Resources Information Center

    Allsup, Randall Everett

    2005-01-01

    A close reading of Gradgrind's opening monologue of Hard Times by Charles Dickens will provide the starting off point for an examination of the role and place of philosophy in the music curriculum. The Gradgrind philosophy finds easy parallel to current thinking in American education. In the fundamentalist imagination, sources of ambiguity must be…

  19. Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

    PubMed

    Humood, Mohammad; Chowdhury, Shahla; Song, Yixuan; Tzeng, Ping; Grunlan, Jaime C; Polycarpou, Andreas A

    2016-05-04

    Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g., food and electronics). Films were prepared from bilayer and quadlayer sequences, with varying thickness and composition. In an effort to evaluate multilayer thin film surface and mechanical properties, and their resistance to failure and wear, a comprehensive range of experiments were conducted: low and high load indentation, low and high load scratch. Some of the thin films were found to have exceptional mechanical behavior and exhibit excellent scratch resistance. Specifically, nanobrick wall structures, comprising montmorillonite (MMT) clay and polyethylenimine (PEI) bilayers, are the most durable coatings. PEI/MMT films exhibit high hardness, large elastic modulus, high elastic recovery, low friction, low scratch depth, and a smooth surface. When combined with the low oxygen permeability and high optical transmission of these thin films, these excellent mechanical properties make them good candidates for hard coating surface-sensitive substrates, where polymers are required to sustain long-term surface aesthetics and quality.

  20. Hard rectangles near curved hard walls: Tuning the sign of the Tolman length

    NASA Astrophysics Data System (ADS)

    Sitta, Christoph E.; Smallenburg, Frank; Wittkowski, Raphael; Löwen, Hartmut

    2016-11-01

    Combining analytic calculations, computer simulations, and classical density functional theory we determine the interfacial tension of orientable two-dimensional hard rectangles near a curved hard wall. Both a circular cavity holding the particles and a hard circular obstacle surrounded by particles are considered. We focus on moderate bulk densities (corresponding to area fractions up to 50%) where the bulk phase is isotropic and vary the aspect ratio of the rectangles and the curvature of the wall. The Tolman length, which gives the leading curvature correction of the interfacial tension, is found to change sign at a finite density, which can be tuned via the aspect ratio of the rectangles.

  1. Hardnesses of metal parts and constructions measured for comparison by small hardness testers with different principles of operation

    NASA Astrophysics Data System (ADS)

    Matyunin, V. M.; Karimbekov, M. A.; Marchenkov, A. Yu.; Demidov, A. N.

    2016-12-01

    The existing handheld and portable hardness testers are classified depending on their operating principles. The advantages and disadvantages of the measurement procedures and the hardness testers are considered. The hardnesses of the metal parts with different masses and stiffness are measured by mechanical and physical-mechanical hardness testers and compared. The test errors are estimated. Recommendations for the calibration of the hardness testers of physical and mechanical operating principles are given.

  2. Ceramic Composite Thin Films

    NASA Technical Reports Server (NTRS)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  3. Super Thin Ceramic Coatings

    NASA Video Gallery

    New technology being developed at NASA's Glenn Research Center creates super thin ceramic coatings on engine components. The Plasma Spray – Physical Vapor Deposition (PS-PVD) rig uses a powerful ...

  4. Thin silicon solar cells

    SciTech Connect

    Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M.

    1992-12-01

    The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

  5. Multifunctional thin film surface

    DOEpatents

    Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

    2015-10-13

    A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

  6. Thin film tritium dosimetry

    DOEpatents

    Moran, Paul R.

    1976-01-01

    The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

  7. Metallurgical coatings and thin films; Proceedings of the International Conference, 18th, San Diego, CA, Apr. 22-26, 1991. Vols. 1 & 2

    NASA Technical Reports Server (NTRS)

    Mcguire, Gary E. (Editor); Mcintyre, Dale C. (Editor); Hofmann, Siegfried (Editor)

    1991-01-01

    A conference on metallurgical coatings and thin films produced papers in the areas of coatings for use at high temperatures; hard coatings and deposition technologies; diamonds and related materials; tribological coatings/surface modifications; thin films for microelectronics and high temperature superconductors; optical coatings, film characterization, magneto-optics, and guided waves; and methods for characterizing films and modified surfaces.

  8. Effect of deposition time on structural and magnetic properties of pulse laser deposited hard-soft composite films

    NASA Astrophysics Data System (ADS)

    Satalkar, M.; Kane, S. N.; Pasko, A.; LoBue, M.; Mazaleyrat, F.

    2016-10-01

    Hard-soft composite (BaFe12O19:Mg0.1Ni0.3Zn0.6Fe2O4 (2:1) films, were deposited by ‘Pulsed Laser Deposition’ (PLD) technique on Si (100) substrate using different deposition time - 30, 60, 90 and 120 minutes. Influence of deposition time on structural and magnetic properties were studied via X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). XRD confirms the presence of soft and hard phases in all the prepared thin films. Small amount of secondary phase - Fe2O3 is also detected in all the thin films except for the deposition time - 90 mins. With deposition time average grain diameter of both hard (BaFe12O19) and soft (Mg0.1Ni0.3Zn0.6Fe2O4) phase increases. Increase in the distance between the magnetic ions (Ni2+ and Fe3+) at tetrahedral (A) and octahedral [B] site leads to increase in the hopping length at A and B site except for the the deposition time of 60 minutes. Magnetic measurements shows that the coercivity and magnetization of the prepared thin films respectively ranges between 112.07 - 213.03 Oe and 1.4 x 10-7 - 3.15 x 10-7 Am2.

  9. Voronoi neighbor statistics of hard-disks and hard-spheres

    NASA Astrophysics Data System (ADS)

    Kumar, V. Senthil; Kumaran, V.

    2005-08-01

    The neighbor distribution in hard-sphere and hard-disk fluids is analyzed using Voronoi tessellation. The statistical measures analyzed are the nth neighbor coordination number (Cn), the nth neighbor distance distribution [fn(r )], and the distribution of the number of Voronoi faces (Pn). These statistics are sensitive indicators of microstructure, and they distinguish thermodynamic and annealed structures. A sharp rise in the hexagon population marks the onset of hard-disk freezing transition, and Cn decreases sharply to the hexagonal lattice values. In hard-disk random structures the pentagon and heptagon populations remain significant even at high volume fraction. In dense hard-sphere (three-dimensional) structures at the freezing transition, C1 is close to 14, instead of the value of 12 expected for a face-centered-cubic lattice. This is found to be because of a topological instability, where a slight perturbation of the positions in the centers of a pair of particles transforms a vertex in the Voronoi polyhedron into a Voronoi surface. We demonstrate that the pair distribution function and the equation-of-state obtained from Voronoi tessellation are equal to those obtained from thermodynamic calculations. In hard-sphere random structures, the dodecahedron population decreases with increasing density. To demonstrate the utility of the neighbor analysis, we estimate the effective hard-sphere diameter of the Lennard-Jones fluid by identifying the diameter of the spheres in the hard-sphere fluid which has C1 equal to that for the Lennard-Jones fluid. The estimates are within 2% deviation from the theoretical results of Barker-Henderson and Weeks-Chandler-Andersen.

  10. Bond-orientational analysis of hard-disk and hard-sphere structures.

    PubMed

    Senthil Kumar, V; Kumaran, V

    2006-05-28

    We report the bond-orientational analysis results for the thermodynamic, random, and homogeneously sheared inelastic structures of hard-disks and hard-spheres. The thermodynamic structures show a sharp rise in the order across the freezing transition. The random structures show the absence of crystallization. The homogeneously sheared structures get ordered at a packing fraction higher than the thermodynamic freezing packing fraction, due to the suppression of crystal nucleation. On shear ordering, strings of close-packed hard-disks in two dimensions and close-packed layers of hard-spheres in three dimensions, oriented along the velocity direction, slide past each other. Such a flow creates a considerable amount of fourfold order in two dimensions and body-centered-tetragonal (bct) structure in three dimensions. These transitions are the flow analogs of the martensitic transformations occurring in metals due to the stresses induced by a rapid quench. In hard-disk structures, using the bond-orientational analysis we show the presence of fourfold order. In sheared inelastic hard-sphere structures, even though the global bond-orientational analysis shows that the system is highly ordered, a third-order rotational invariant analysis shows that only about 40% of the spheres have face-centered-cubic (fcc) order, even in the dense and near-elastic limits, clearly indicating the coexistence of multiple crystalline orders. When layers of close-packed spheres slide past each other, in addition to the bct structure, the hexagonal-close-packed (hcp) structure is formed due to the random stacking faults. Using the Honeycutt-Andersen pair analysis and an analysis based on the 14-faceted polyhedra having six quadrilateral and eight hexagonal faces, we show the presence of bct and hcp signatures in shear ordered inelastic hard-spheres. Thus, our analysis shows that the dense sheared inelastic hard-spheres have a mixture of fcc, bct, and hcp structures.

  11. Further links between the maximum hardness principle and the hard/soft acid/base principle: insights from hard/soft exchange reactions.

    PubMed

    Chattaraj, Pratim K; Ayers, Paul W; Melin, Junia

    2007-08-07

    Ayers, Parr, and Pearson recently showed that insight into the hard/soft acid/base (HSAB) principle could be obtained by analyzing the energy of reactions in hard/soft exchange reactions, i.e., reactions in which a soft acid replaces a hard acid or a soft base replaces a hard base [J. Chem. Phys., 2006, 124, 194107]. We show, in accord with the maximum hardness principle, that the hardness increases for favorable hard/soft exchange reactions and decreases when the HSAB principle indicates that hard/soft exchange reactions are unfavorable. This extends the previous work of the authors, which treated only the "double hard/soft exchange" reaction [P. K. Chattaraj and P. W. Ayers, J. Chem. Phys., 2005, 123, 086101]. We also discuss two different approaches to computing the hardness of molecules from the hardness of the composing fragments, and explain how the results differ. In the present context, it seems that the arithmetic mean of fragment softnesses is the preferable definition.

  12. Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

    PubMed

    Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

    2013-01-01

    The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

  13. Remember Hard But Think Softly: Metaphorical Effects of Hardness/Softness on Cognitive Functions

    PubMed Central

    Xie, Jiushu; Lu, Zhi; Wang, Ruiming; Cai, Zhenguang G.

    2016-01-01

    Previous studies have found that bodily stimulation, such as hardness biases social judgment and evaluation via metaphorical association; however, it remains unclear whether bodily stimulation also affects cognitive functions, such as memory and creativity. The current study used metaphorical associations between “hard” and “rigid” and between “soft” and “flexible” in Chinese, to investigate whether the experience of hardness affects cognitive functions whose performance depends prospectively on rigidity (memory) and flexibility (creativity). In Experiment 1, we found that Chinese-speaking participants performed better at recalling previously memorized words while sitting on a hard-surface stool (the hard condition) than a cushioned one (the soft condition). In Experiment 2, participants sitting on a cushioned stool outperformed those sitting on a hard-surface stool on a Chinese riddle task, which required creative/flexible thinking, but not on an analogical reasoning task, which required both rigid and flexible thinking. The results suggest the hardness experience affects cognitive functions that are metaphorically associated with rigidity or flexibility. They support the embodiment proposition that cognitive functions and representations can be grounded in bodily states via metaphorical associations. PMID:27672373

  14. Is hyper-hardness more chemically relevant than expected?

    PubMed

    Morell, Christophe; Grand, André; Toro-Labbé, Alejandro; Chermette, Henry

    2013-07-01

    In this work, the third derivative of the energy with respect to the number of electrons, the so-called hyper-hardness, is investigated to assess whether this quantity has a chemical meaning. To achieve this goal a new working expression for hyper-hardness is developed and analyzed. It transpired from this analysis that hyper-hardness, just like hardness, can measure the reactivity or the stability of electron systems. Interestingly, positive values of hyper-hardness point to quite stable species such as noble gases and molecules. On the other hand, radicals almost always display large negative values of hyper-hardness.

  15. The hardness, adhesion, and wear resistance of coatings developed for cobalt-base alloys

    SciTech Connect

    Cockeram, B.V.; Wilson, W.L.

    2000-05-01

    One potential approach for reducing the level of nuclear plant radiation exposure that results from activated cobalt wear debris is the use of a wear resistant coating. However, large differences in stiffness between a coating/substrate can result in high interfacial stresses that produce coating de-adhesion when a coated substrate is subjected to high stress wear contact. Scratch adhesion and indentation tests have been used to identify four promising coating processes [1,2]: (1) the use of a thin Cr-nitride coating with a hard and less-stiff interlayer, (2) the use of a thick, multilayered Cr-nitride coating with graded layers, (3) use of the duplex approach, or nitriding to harden the material subsurface followed by application of a multilayered Cr-nitride coating, and (4) application of nitriding alone. The processing, characterization, and adhesion of these coating systems are discussed. The wear resistance and performance has been evaluated using laboratory pin-on-disc, 4-ball, and high stress rolling contact tests. Based on the results of these tests, the best coating candidate from the high-stress rolling contact wear test was the thin duplex coating, which consists of ion nitriding followed deposition of a thin Cr-nitride coating, while the thin Cr-nitride coating exhibited the best results in the 4-ball wear test.

  16. Fixed target electroweak and hard scattering physics

    SciTech Connect

    Brock, R. ); Brown, C.N.; Montgomery, H.E. ); Corcoran, M.D. )

    1990-02-01

    The possibilities for future physics and experiments involving weak and electromagnetic interactions, neutrino oscillations, general hard scattering and experiments involving nuclear targets were explored. The studies were limited to the physics accessible using fixed target experimentation. While some of the avenues explored turn out to be relatively unrewarding in the light of competition elsewhere in the world, there are a number of positive conclusions reached about experimentation in the energy range available to the Main Injector and Tevatron. Some of the experiments would benefit from the increased intensity available from the Tevatron utilizing the Main Injector, while some require this increase. Finally, some of the experiments would use the Main Injector low energy, high intensity extracted beams directly. A program of electroweak and hard scattering experiments at fixed target energies retains the potential for important contributions to physics. The key to major parts of this program would appear to be the existence of the Main Injector. 115 refs, 17 figs.

  17. Anomalous structural transition of confined hard squares.

    PubMed

    Gurin, Péter; Varga, Szabolcs; Odriozola, Gerardo

    2016-11-01

    Structural transitions are examined in quasi-one-dimensional systems of freely rotating hard squares, which are confined between two parallel walls. We find two competing phases: one is a fluid where the squares have two sides parallel to the walls, while the second one is a solidlike structure with a zigzag arrangement of the squares. Using transfer matrix method we show that the configuration space consists of subspaces of fluidlike and solidlike phases, which are connected with low probability microstates of mixed structures. The existence of these connecting states makes the thermodynamic quantities continuous and precludes the possibility of a true phase transition. However, thermodynamic functions indicate strong tendency for the phase transition and our replica exchange Monte Carlo simulation study detects several important markers of the first order phase transition. The distinction of a phase transition from a structural change is practically impossible with simulations and experiments in such systems like the confined hard squares.

  18. Laser ablated hard coating for microtools

    DOEpatents

    McLean, W. II; Balooch, M.; Siekhaus, W.J.

    1998-05-05

    Wear-resistant coatings composed of laser ablated hard carbon films, are deposited by pulsed laser ablation using visible light, on instruments such as microscope tips and micro-surgical tools. Hard carbon, known as diamond-like carbon (DLC), films produced by pulsed laser ablation using visible light enhances the abrasion resistance, wear characteristics, and lifetimes of small tools or instruments, such as small, sharp silicon tips used in atomic probe microscopy without significantly affecting the sharpness or size of these devices. For example, a 10--20 nm layer of diamond-like carbon on a standard silicon atomic force microscope (AFM) tip, enables the useful operating life of the tip to be increased by at least twofold. Moreover, the low inherent friction coefficient of the DLC coating leads to higher resolution for AFM tips operating in the contact mode. 12 figs.

  19. Hardness/intensity correlations among BATSE bursts

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Pendleton, Geoffrey N.; Kouveliotou, Chryssa; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.

    1992-01-01

    Conclusions about the nature of gamma-ray bursts derived from the size-frequency distribution may be altered if a significant correlation exists between burst intensity and spectral shape. Moreover, if gamma-ray bursts have a cosmological origin, such a correlation may be expected to result from the expansion of the universe. We have performed a rudimentary search of the BATSE bursts for hardness/intensity correlations. The range of spectral shapes was determined for each burst by computing the ratio of the intensity in the range 100-300 keV to that in 55-300 keV. We find weak evidence for the existence of a correlation, the strongest effect being present when comparing the maximum hardness ratio for each burst with its maximum rate.

  20. Laser ablated hard coating for microtools

    DOEpatents

    McLean, II, William; Balooch, Mehdi; Siekhaus, Wigbert J.

    1998-05-05

    Wear-resistant coatings composed of laser ablated hard carbon films, are deposited by pulsed laser ablation using visible light, on instruments such as microscope tips and micro-surgical tools. Hard carbon, known as diamond-like carbon (DLC), films produced by pulsed laser ablation using visible light enhances the abrasion resistance, wear characteristics, and lifetimes of small tools or instruments, such as small, sharp silicon tips used in atomic probe microscopy without significantly affecting the sharpness or size of these devices. For example, a 10-20 nm layer of diamond-like carbon on a standard silicon atomic force microscope (AFM) tip, enables the useful operating life of the tip to be increased by at least twofold. Moreover, the low inherent friction coefficient of the DLC coating leads to higher resolution for AFM tips operating in the contact mode.

  1. Hard X-Ray Radio Galaxies

    NASA Astrophysics Data System (ADS)

    Panessa, Francesca; Bassani, L.; Venturi, T.; Molina, M.; Dallacasa, D.; Ubertini, P.; Bazzano, A.; Malizia, A.; La Franca, F.; Landi, R.

    2016-10-01

    In order to investigate the role of absorption in AGN with jets, we have studied the column density distribution of a hard X-ray selected sample of radio galaxies, derived from the INTEGRAL/IBIS and Swift/BAT AGN catalogues. They represent 7-10% of the total AGN population and are characterized by high 20-100 keV luminosities and high Eddington ratios. The radio morphology is typical of FRII galaxies and all of them have an optical classification and a measure of the column density. The observed fraction of absorbed AGN is around 40% among the total sample, and 75% among type 2 AGN. The observed fraction of Compton thick AGN is 2-3%. In this talk we will discuss the obscuration characteristics of radio galaxies compared to non-radio galaxies selected at hard X-rays.

  2. The k-Anonymity Problem Is Hard

    NASA Astrophysics Data System (ADS)

    Bonizzoni, Paola; Della Vedova, Gianluca; Dondi, Riccardo

    The problem of publishing personal data without giving up privacy is becoming increasingly important. An interesting formalization recently proposed is the k-anonymity. This approach requires that the rows in a table are clustered in sets of size at least k and that all the rows in a cluster are related to the same tuple, after the suppression of some records. The problem has been shown to be NP-hard when the values are over a ternary alphabet, k = 3 and the rows length is unbounded. In this paper we give a lower bound on the approximation of two restrictions of the problem, when the records values are over a binary alphabet and k = 3, and when the records have length at most 8 and k = 4, showing that these restrictions of the problem are APX-hard.

  3. Superhard material comparable in hardness to diamond

    SciTech Connect

    Badzian, A.R.

    1988-12-19

    Superhard boron suboxides, with hardness close to that of diamond, were synthesized from boron/boron oxide mixtures. Such hardness is expected when a material's molar volume approaches the value characteristic for diamond. These materials consist of boron-rich phases belonging to the boron-oxygen system. The phase which contains 4 at. % oxygen and a crystal structure related to ..beta..rhombohedral boron can scratch diamond faces. During scratching of diamond the suboxide is worn also, and the wear debris is amorphized. Wear on the lt. slash/100/ diamond faces results from a cleavage mechanism which leaves a rough surface covered with cleaved lt. slash/111/ microfaces. The lt. slash/100/ faces are more easily abraded than the lt. slash/111/ diamond faces. Wear on lt. slash/111/ faces consumes much more energy and leaves grooves of plastically deformed diamond.

  4. Mechanical properties of Al/a-C nanocomposite thin films synthesized using a plasma focus device

    NASA Astrophysics Data System (ADS)

    A. Umar, Z.; S. Rawat, R.; R., Ahmad; K. Kumar, A.; Y., Wang; Hussain, T.; Z., Chen; Shen, L.; Zhang, Z.

    2014-02-01

    The Al/a-C nanocomposite thin films are synthesized on Si substrates using a dense plasma focus device with aluminum fitted anode and operating with CH4/Ar admixture. X-ray diffractometer results confirm the formation of metallic crystalline Al phases using different numbers of focus shots. Raman analyses show the formation of D and G peaks for all thin film samples, confirming the presence of a-C in the nanocomposite thin films. The formation of Al/a-C nanocomposite thin films is further confirmed using X-ray photoelectron spectroscopy analysis. The scanning electron microscope results show that the deposited thin films consist of nanoparticles and their agglomerates. The sizes of th agglomerates increase with increasing numbers of focus deposition shots. The nanoindentation results show the variations in hardness and elastic modulus values of nanocomposite thin film with increasing the number of focus shots. Maximum values of hardness and elastic modulus of the composite thin film prepared using 20 focus shots are found to be about 10.7 GPa and 189.2 GPa, respectively.

  5. CMS results on soft and hard diffraction

    NASA Astrophysics Data System (ADS)

    Obertino, M. M.

    2017-03-01

    The measurement of the soft diffractive cross sections in single- and double-diffractive final states is presented at 7 TeV. Furthermore, the production of jet-gap-jet final states is discussed and the results are interpreted in terms of a hard color singlet exchange. Finally, general features of particle production in single-diffractive enhanced events are shown at 13 TeV.

  6. Radiation Hardness Assurance for Space Systems

    NASA Technical Reports Server (NTRS)

    Poivey, Christian; Day, John H. (Technical Monitor)

    2002-01-01

    The space radiation environment can lead to extremely harsh operating conditions for on-board electronic box and systems. The characteristics of the radiation environment are highly dependent on the type of mission (date, duration and orbit). Radiation accelerates the aging of the electronic parts and material and can lead to a degradation of electrical performance; it can also create transient phenomena on parts. Such damage at the part level can induce damage or functional failure at electronic box, subsystem, and system levels. A rigorous methodology is needed to ensure that the radiation environment does not compromise the functionality and performance of the electronics during the system life. This methodology is called hardness assurance. It consists of those activities undertaken to ensure that the electronic piece parts placed in the space system perform to their design specifications after exposure to the space environment. It deals with system requirements, environmental definitions, part selection, part testing, shielding and radiation tolerant design. All these elements should play together in order to produce a system tolerant to.the radiation environment. An overview of the different steps of a space system hardness assurance program is given in section 2. In order to define the mission radiation specifications and compare these requirements to radiation test data, a detailed knowledge of the space environment and the corresponding electronic device failure mechanisms is required. The presentation by J. Mazur deals with the Earth space radiation environment as well as the internal environment of a spacecraft. The presentation by J. Schwank deals with ionization effects, and the presentation by T. Weatherford deals with Single particle Event Phenomena (SEP) in semiconductor devices and microcircuits. These three presentations provide more detailed background to complement the sections 3 and 4. Part selection and categorization are discussed in section

  7. Experiments on asteroids using hard landers

    NASA Technical Reports Server (NTRS)

    Turkevich, A.; Economou, T.

    1978-01-01

    Hard lander missions to asteroids are examined using the Westphal penetrator study as a basis. Imagery and chemical information are considered to be the most significant science to be obtained. The latter, particularly a detailed chemical analysis performed on an uncontaminated sample, may answer questions about the relationships of asteroids to meteorites and the place of asteroids in theories of the formation of the solar system.

  8. Dynamic Hardness Tester and Cure Meter

    NASA Technical Reports Server (NTRS)

    Madigosky, Walter M.; Fiorito, Ralph B.

    1993-01-01

    The Shore hardness tester is used extensively throughout industry to determine the static modulus of materials. The new apparatus described here extends the capability of an indentor-type tester into the dynamic regime, and provides a measurement of the dynamic shear or Young's modulus and loss factor as a function of frequency. The instrument, model and data of typical rubber samples are given and compared to other dynamic measurements.

  9. Rad-Hard/HI-REL FPGA

    NASA Technical Reports Server (NTRS)

    Wang, Jih-Jong; Cronquist, Brian E.; McGowan, John E.; Katz, Richard B.

    1997-01-01

    The goals for a radiation hardened (RAD-HARD) and high reliability (HI-REL) field programmable gate array (FPGA) are described. The first qualified manufacturer list (QML) radiation hardened RH1280 and RH1020 were developed. The total radiation dose and single event effects observed on the antifuse FPGA RH1280 are reported on. Tradeoffs and the limitations in the single event upset hardening are discussed.

  10. Colour hard-copy from workstation screens

    NASA Astrophysics Data System (ADS)

    Clayton, C. A.

    It is possible to produce a colour print on the DEC LJ250 inkjet printer of either the entire screen or a portion of the screen from VAXstations, DECstations, SUN workstations and the IKON image display. This document describes how to achieve this with each of the above workstations. The IKONPAINT software which is used to produce colour hard-copy from the IKON screen on the inkjet printer is fully documented in SUN/71 and is not described here.

  11. Nanotwinned diamond with unprecedented hardness and stability.

    PubMed

    Huang, Quan; Yu, Dongli; Xu, Bo; Hu, Wentao; Ma, Yanming; Wang, Yanbin; Zhao, Zhisheng; Wen, Bin; He, Julong; Liu, Zhongyuan; Tian, Yongjun

    2014-06-12

    Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable. According to the Hall-Petch effect, the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies. However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30 nm (ref. 3), with degraded thermal stability compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to ∼3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability. At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors (such as graphite, amorphous carbon, glassy carbon and C60). Here we report the direct synthesis of nt-diamond with an average twin thickness of ∼5 nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to ∼200 GPa and an in-air oxidization temperature more than 200 °C higher than that of natural diamond. The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties.

  12. Hard and soft acids and bases: atoms and atomic ions.

    PubMed

    Reed, James L

    2008-07-07

    The structural origin of hard-soft behavior in atomic acids and bases has been explored using a simple orbital model. The Pearson principle of hard and soft acids and bases has been taken to be the defining statement about hard-soft behavior and as a definition of chemical hardness. There are a number of conditions that are imposed on any candidate structure and associated property by the Pearson principle, which have been exploited. The Pearson principle itself has been used to generate a thermodynamically based scale of relative hardness and softness for acids and bases (operational chemical hardness), and a modified Slater model has been used to discern the electronic origin of hard-soft behavior. Whereas chemical hardness is a chemical property of an acid or base and the operational chemical hardness is an experimental measure of it, the absolute hardness is a physical property of an atom or molecule. A critical examination of chemical hardness, which has been based on a more rigorous application of the Pearson principle and the availability of quantitative measures of chemical hardness, suggests that the origin of hard-soft behavior for both acids and bases resides in the relaxation of the electrons not undergoing transfer during the acid-base interaction. Furthermore, the results suggest that the absolute hardness should not be taken as synonymous with chemical hardness but that the relationship is somewhat more complex. Finally, this work provides additional groundwork for a better understanding of chemical hardness that will inform the understanding of hardness in molecules.

  13. Laser Deposition of Polymer Nanocomposite Thin Films and Hard Materials and Their Optical Characterization

    DTIC Science & Technology

    2013-12-05

    results in hexagonal symmetry (s.g. P63/m). This material is typically prepared by low temperature techniques (and is the phase synthesized ...experiments were conducted to evaluate the response of the films to ammonia , hazardous air pollutant. The example of the differential optical absorption...reagent with nano-particles under exposure to ammonia at a concentration of ~ 10000 ppm transmitted 100 times less light on both sides of the 605

  14. Condensation transition in polydisperse hard rods.

    PubMed

    Evans, M R; Majumdar, S N; Pagonabarraga, I; Trizac, E

    2010-01-07

    We study a mass transport model, where spherical particles diffusing on a ring can stochastically exchange volume v, with the constraint of a fixed total volume V= sum(i=1) (N)v(i), N being the total number of particles. The particles, referred to as p-spheres, have a linear size that behaves as v(i) (1/p) and our model thus represents a gas of polydisperse hard rods with variable diameters v(i) (1/p). We show that our model admits a factorized steady state distribution which provides the size distribution that minimizes the free energy of a polydisperse hard-rod system, under the constraints of fixed N and V. Complementary approaches (explicit construction of the steady state distribution on the one hand; density functional theory on the other hand) completely and consistently specify the behavior of the system. A real space condensation transition is shown to take place for p>1; beyond a critical density a macroscopic aggregate is formed and coexists with a critical fluid phase. Our work establishes the bridge between stochastic mass transport approaches and the optimal polydispersity of hard sphere fluids studied in previous articles.

  15. Hard Constraints in Optimization Under Uncertainty

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Giesy, Daniel P.; Kenny, Sean P.

    2008-01-01

    This paper proposes a methodology for the analysis and design of systems subject to parametric uncertainty where design requirements are specified via hard inequality constraints. Hard constraints are those that must be satisfied for all parameter realizations within a given uncertainty model. Uncertainty models given by norm-bounded perturbations from a nominal parameter value, i.e., hyper-spheres, and by sets of independently bounded uncertain variables, i.e., hyper-rectangles, are the focus of this paper. These models, which are also quite practical, allow for a rigorous mathematical treatment within the proposed framework. Hard constraint feasibility is determined by sizing the largest uncertainty set for which the design requirements are satisfied. Analytically verifiable assessments of robustness are attained by comparing this set with the actual uncertainty model. Strategies that enable the comparison of the robustness characteristics of competing design alternatives, the description and approximation of the robust design space, and the systematic search for designs with improved robustness are also proposed. Since the problem formulation is generic and the tools derived only require standard optimization algorithms for their implementation, this methodology is applicable to a broad range of engineering problems.

  16. Hard hadronic collisions: extrapolation of standard effects

    SciTech Connect

    Ali, A.; Aurenche, P.; Baier, R.; Berger, E.; Douiri, A.; Fontannaz, M.; Humpert, B.; Ingelman, G.; Kinnunen, R.; Pietarinen, E.

    1984-01-01

    We study hard hadronic collisions for the proton-proton (pp) and the proton-antiproton (p anti p) option in the CERN LEP tunnel. Based on our current knowledge of hard collisions at the present CERN p anti p Collider, and with the help of quantum chromodynamics (QCD), we extrapolate to the next generation of hadron colliders with a centre-of-mass energy E/sub cm/ = 10 to 20 TeV. We estimate various signatures, trigger rates, event topologies, and associated distributions for a variety of old and new physical processes, involving prompt photons, leptons, jets, W/sup + -/ and Z bosons in the final state. We also calculate the maximum fermion and boson masses accessible at the LEP Hadron Collider. The standard QCD and electroweak processes studied here, being the main body of standard hard collisions, quantify the challenge of extracting new physics with hadron colliders. We hope that our estimates will provide a useful profile of the final states, and that our experimental physics colleagues will find this of use in the design of their detectors. 84 references.

  17. Surgical lasers and hard dental tissue.

    PubMed

    Parker, S

    2007-04-28

    The cutting of dental hard tissue during restorative procedures presents considerable demands on the ability to selectively remove diseased carious tissue, obtain outline and retention form and maintain the integrity of supporting tooth tissue without structural weakening. In addition, the requirement to preserve healthy tissue and prevent further breakdown of the restoration places the choice of instrumentation and clinical technique as prime factors for the dental surgeon. The quest for an alternative treatment modality to the conventional dental turbine has been, essentially, patient-driven and has led to the development of various mechanical and chemical devices. The review of the literature has endorsed the beneficial effects of current laser machines. However utopian, there is additional evidence to support the development of ultra-short (nano- and femto-second) pulsed lasers that are stable in use and commercially viable, to deliver more efficient hard tissue ablation with less risk of collateral thermal damage. This paper explores the interaction of laser energy with dental hard tissues and bone and the integration of current laser wavelengths into restorative and surgical dentistry.

  18. Water hardness and urinary stone disease.

    PubMed

    Shuster, J; Finlayson, B; Scheaffer, R; Sierakowski, R; Zoltek, J; Dzegede, S

    1982-08-01

    On the macrogeographic scale, a strong negative association exists in the United States between water hardness and urinary stone disease. This investigation studies the association on the microgeographical scale, where it is possible to control for confounding environmental factors. The study was conducted on 2,295 patients from 2 regions: the Carolinas which had soft water and high stone incidence, and the Rockies which had hard water and low stone incidence. Home tap water samples from urinary stone patient hospitalizations were compared with that of controls, concurrent inguinal hernia patient hospitalization. After adjusting for environmental factors, no significant difference (p = 0.59) between the 2 groups was obtained in tap water calcium, magnesium, and sodium concentrations. An incidental but potentially important finding was that those consuming water from a private well had an estimated relative risk of 1.5 (p less than 0.01) compared to those using public water. While no cause-effect relationship is suggested, stone-formers might consider avoiding private well water. On the other hand, water hardness should be a minor concern with respect to stone formation.

  19. Structural and mechanical properties of magnetron-sputtered Al-Au thin films

    NASA Astrophysics Data System (ADS)

    Azadmanjiri, Jalal; Wang, James; Berndt, Christopher C.; Wen, Cuie; Srivastava, Vijay K.; Kapoor, Ajay

    2017-01-01

    There is global interest in improving the mechanical properties of light metals such as aluminum (Al)-based alloys by tailoring their microstructures at the nanometer scale. On the other hand, gold (Au) has been widely applied as a wire bonding material due to its prominent ductility and conductivity. In this study, the microstructure, hardness and elastic modulus of DC magnetron-sputtered aluminum/gold (Al/Au) composite thin films of different thicknesses were investigated. It is shown that in addition to the formation of AlAu2 phase, additional Al and Au nanosegregated phases also formed. The Al/Au thin films of 600 and 800 nm thickness exhibit the maximum hardness ( 5.40 GPa) and elastic modulus ( 97.00 GPa). However, film thicknesses of 1000 and 1200 nm demonstrate a reduction in hardness and elastic modulus due to different growth mechanisms and the formation of voids that can be attributed to the Kirkendall phenomenon.

  20. Effect of Grain Curvature on Nano-Indentation Measurements of Thin Films

    NASA Astrophysics Data System (ADS)

    Tsai, Kuang-Yue; Chin, Tsung-Shune; Shieh, Han-Ping D.

    2004-09-01

    Grain curvature effect on the measurement of nano-indentation has been observed for the first time, taking VO2 thin film as an example. As the grain size of thin film is comparable to the diameter of indenter tip, the maximum penetration depths under the same maximum load (Pmax) vary and lead to deviations in estimated hardness and Young’s modulus. Under the same Pmax, larger penetration depth leads to a larger projected area, and a decrease in hardness. The large deviation of stiffness, affected by surface roughness under low Pmax, produces fluctuation of Young’s modulus. Increase in penetration depth diminishes the roughness effect so that deviations in penetration depths dominate the variations in Young’s modulus. The hardness and Young’s modulus curves measured at lowest penetration depth, being thought to be free from effect of grain curvature, coincide very well to the curves measured by continuous stiffness measurements mode.

  1. Epitaxial thinning process

    NASA Technical Reports Server (NTRS)

    Siegel, C. M. (Inventor)

    1984-01-01

    A method is described for thinning an epitaxial layer of a wafer that is to be used in producing diodes having a specified breakdown voltage and which also facilitates the thinning process. Current is passed through the epitaxial layer, by connecting a current source between the substrate of the wafer and an electrolyte in which the wafer is immersed. When the wafer is initially immersed, the voltage across the wafer initially drops and then rises at a steep rate. When light is applied to the wafer the voltage drops, and when the light is interrupted the voltage rises again. These changes in voltage, each indicate the breakdown voltage of a Schottky diode that could be prepared from the wafer at that time. The epitaxial layer is thinned by continuing to apply current through the wafer while it is immersed and light is applied, to form an oxide film and when the oxide film is thick the wafer can then be cleaned of oxide and the testing and thinning continued. Uninterrupted thinning can be achieved by first forming an oxide film, and then using an electrolyte that dissolves the oxide about as fast as it is being formed, to limit the thickness of the oxide layer.

  2. Lithospheric and crustal thinning

    NASA Technical Reports Server (NTRS)

    Moretti, I.

    1985-01-01

    In rift zones, both the crust and the lithosphere get thinner. The amplitude and the mechanism of these two thinning situations are different. The lithospheric thinning is a thermal phenomenon produced by an asthenospherical uprising under the rift zone. In some regions its amplitude can exceed 200%. This is observed under the Baikal rift where the crust is directly underlaid by the mantellic asthenosphere. The presence of hot material under rift zones induces a large negative gravity anomaly. A low seismic velocity zone linked to this thermal anomaly is also observed. During the rifting, the magmatic chambers get progressively closer from the ground surface. Simultaneously, the Moho reflector is found at shallow depth under rift zones. This crustal thinning does not exceed 50%. Tectonic stresses and vertical movements result from the two competing effects of the lithospheric and crustal thinning. On the one hand, the deep thermal anomaly induces a large doming and is associated with extensive deviatoric stresses. On the other hand, the crustal thinning involves the formation of a central valley. This subsidence is increased by the sediment loading. The purpose here is to quantify these two phenomena in order to explain the morphological and thermal evolution of rift zones.

  3. Observational evidence for thin AGN disks

    NASA Technical Reports Server (NTRS)

    Netzer, Hagai

    1992-01-01

    AGN spectrum and spectral features, polarization, inclination, and X-ray line and continuum reflection features are discussed in a critical way in order to determine the ones that are the least model-dependent. The sign and strength of absorption and emission edges are found to be model-dependent, and relativistic broadening and shifting makes them hard to detect. The presence or absence of the predicted Lyman edge polarization feature may be used as a decisive test for thin, bare AGN disks. Other good model-independent tests are several inclination-related line and continuum correlations in big AGN samples. It is shown that electron temperature near the surface of the disk can greatly exceed the disk equilibrium temperature, which causes deviations from LTE. This effect must be incorporated into realistic disk models.

  4. Surface Morphological and Nanomechanical Properties of PLD-Derived ZnO Thin Films

    PubMed Central

    2008-01-01

    This study reports the surface roughness and nanomechanical characteristics of ZnO thin films deposited on the various substrates, obtained by means of atomic force microscopy (AFM), nanoindentation and nanoscratch techniques. ZnO thin films are deposited on (a- and c-axis) sapphires and (0001) 6H-SiC substrates by using the pulsed-laser depositions (PLD) system. Continuous stiffness measurements (CSM) technique is used in the nanoindentation tests to determine the hardness and Young’s modulus of ZnO thin films. The importance of the ratio (H/Efilm) of elastic to plastic deformation during nanoindentation of ZnO thin films on their behaviors in contact-induced damage during fabrication of ZnO-based devices is considered. In addition, the friction coefficient of ZnO thin films is also presented here.

  5. Mechanically robust, thermally stable, broadband antireflective, and superhydrophobic thin films on glass substrates.

    PubMed

    Xu, Ligang; Geng, Zhi; He, Junhui; Zhou, Gang

    2014-06-25

    In this study, we developed a simple and versatile strategy to fabricate hierarchically structured lotus-leaf-like superhydrophobic thin films. The thin films are broadband antireflective, and the average transmittance of coated glass substrates reached greater than 95% in the wavelength range of 530-1340 nm, in contrast to 92.0% for bare glass substrate. The thin film surface shows a static water contact angle of 162° and a sliding angle less than 4°. Moreover, the thin film is thermally stable up to 300 °C, and shows remarkable stability against strong acid, strong alkali, water drop impact, and sand impact abrasion, while retaining its superhydrophobicity. Further, the thin film can pass the 3H pencil hardness test. The current approach may open a new avenue to a variety of practical applications, including windshields, eyeglasses, windows of high rise buildings and solar cells, etc.

  6. Fault-Tolerant, Radiation-Hard DSP

    NASA Technical Reports Server (NTRS)

    Czajkowski, David

    2011-01-01

    Commercial digital signal processors (DSPs) for use in high-speed satellite computers are challenged by the damaging effects of space radiation, mainly single event upsets (SEUs) and single event functional interrupts (SEFIs). Innovations have been developed for mitigating the effects of SEUs and SEFIs, enabling the use of very-highspeed commercial DSPs with improved SEU tolerances. Time-triple modular redundancy (TTMR) is a method of applying traditional triple modular redundancy on a single processor, exploiting the VLIW (very long instruction word) class of parallel processors. TTMR improves SEU rates substantially. SEFIs are solved by a SEFI-hardened core circuit, external to the microprocessor. It monitors the health of the processor, and if a SEFI occurs, forces the processor to return to performance through a series of escalating events. TTMR and hardened-core solutions were developed for both DSPs and reconfigurable field-programmable gate arrays (FPGAs). This includes advancement of TTMR algorithms for DSPs and reconfigurable FPGAs, plus a rad-hard, hardened-core integrated circuit that services both the DSP and FPGA. Additionally, a combined DSP and FPGA board architecture was fully developed into a rad-hard engineering product. This technology enables use of commercial off-the-shelf (COTS) DSPs in computers for satellite and other space applications, allowing rapid deployment at a much lower cost. Traditional rad-hard space computers are very expensive and typically have long lead times. These computers are either based on traditional rad-hard processors, which have extremely low computational performance, or triple modular redundant (TMR) FPGA arrays, which suffer from power and complexity issues. Even more frustrating is that the TMR arrays of FPGAs require a fixed, external rad-hard voting element, thereby causing them to lose much of their reconfiguration capability and in some cases significant speed reduction. The benefits of COTS high

  7. Hard and soft acids and bases: small molecules.

    PubMed

    Reed, James L

    2009-08-03

    The operational chemical hardness has been determined for the hydride, chloride, and fluoride derivatives of the anionic atomic bases of the second period. Of interest is the identification of the structure and associated processes that give rise to hard-soft behavior in small molecules. The Pearson Principle of Hard and Soft Acids and Bases has been taken to be the defining statement about hard-soft behavior and as a definition of chemical hardness. Similar to the case for atoms, the molecule's responding electrons have been identified as the structure giving rise to hard-soft behavior, and a relaxation described by a modified Slater model has been identified as the associated process. The responding electrons are the molecule's valence electrons that are not undergoing electron transfer in an acid-base interaction. However, it has been demonstrated that chemical hardness is a local property, and only those responding electrons that are associated with the base's binding atom directly impact chemical hardness.

  8. Thin film temperature sensor

    NASA Technical Reports Server (NTRS)

    Grant, H. P.; Przybyszewski, J. S.

    1980-01-01

    Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

  9. Hardness of polycrystalline tungsten and molybdenum oxides at elevated temperatures

    SciTech Connect

    Lee, M.; Flom, D.G. . Corporate Research and Development Center)

    1990-07-01

    Vickers hardness of WO{sub 3} W{sub 18}O{sub 49} and MoO{sub 2} is reported for temperatures up to 800{degrees}C. Polycrystalline samples of the oxides were prepared by hot-pressing, and hardness was determined using a Vickers hardness tester modified for high-temperature applications. The hardness of a heavily deformed tungsten rod was also measured as a reference.

  10. Thin film photovoltaic device

    DOEpatents

    Catalano, Anthony W.; Bhushan, Manjul

    1982-01-01

    A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

  11. Shear Thinning in Xenon

    NASA Technical Reports Server (NTRS)

    Bergm Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

    2009-01-01

    We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

  12. Thin film ceramic thermocouples

    NASA Technical Reports Server (NTRS)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  13. Thin-film optical initiator

    DOEpatents

    Erickson, Kenneth L.

    2001-01-01

    A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

  14. Traceability in hardness measurements: from the definition to industry

    NASA Astrophysics Data System (ADS)

    Germak, Alessandro; Herrmann, Konrad; Low, Samuel

    2010-04-01

    The measurement of hardness has been and continues to be of significant importance to many of the world's manufacturing industries. Conventional hardness testing is the most commonly used method for acceptance testing and production quality control of metals and metallic products. Instrumented indentation is one of the few techniques available for obtaining various property values for coatings and electronic products in the micrometre and nanometre dimensional scales. For these industries to be successful, it is critical that measurements made by suppliers and customers agree within some practical limits. To help assure this measurement agreement, a traceability chain for hardness measurement traceability from the hardness definition to industry has developed and evolved over the past 100 years, but its development has been complicated. A hardness measurement value not only requires traceability of force, length and time measurements but also requires traceability of the hardness values measured by the hardness machine. These multiple traceability paths are needed because a hardness measurement is affected by other influence parameters that are often difficult to identify, quantify and correct. This paper describes the current situation of hardness measurement traceability that exists for the conventional hardness methods (i.e. Rockwell, Brinell, Vickers and Knoop hardness) and for special-application hardness and indentation methods (i.e. elastomer, dynamic, portables and instrumented indentation).

  15. Study of hot hardness characteristics of tool steels

    NASA Technical Reports Server (NTRS)

    Chevalier, J. L.; Dietrich, M. W.; Zaretsky, E. V.

    1972-01-01

    Hardness measurements of tool steel materials in electric furnace at elevated temperatures and low oxygen environment are discussed. Development of equation to predict short term hardness as function of intial room temperature hardness of steel is reported. Types of steel involved in the process are identified.

  16. High-order virial coefficients and equation of state for hard sphere and hard disk systems.

    PubMed

    Hu, Jiawen; Yu, Yang-Xin

    2009-11-07

    A very simple and accurate approach is proposed to predict the high-order virial coefficients of hard spheres and hard disks. In the approach, the nth virial coefficient B(n) is expressed as the sum of n(D-1) and a remainder, where D is the spatial dimension of the system. When n > or = 3, the remainders of the virials can be accurately expressed with Padé-type functions of n. The maximum deviations of predicted B(5)-B(10) for the two systems are only 0.0209%-0.0044% and 0.0390%-0.0525%, respectively, which are much better than the numerous existing approaches. The virial equation based on the predicted virials diverges when packing fraction eta = 1. With the predicted virials, the compressibility factors of hard sphere system can be predicted very accurately in the whole stable fluid region, and those in the metastable fluid region can also be well predicted up to eta = 0.545. The compressibility factors of hard disk fluid can be predicted very accurately up to eta = 0.63. The simulated B(7) and B(10) for hard spheres are found to be inconsistent with the other known virials and therefore they are modified as 53.2467 and 105.042, respectively.

  17. Nuclear-chemical methods in a hard tooth tissue abrasion study

    NASA Astrophysics Data System (ADS)

    Gosman, A.; Spěváček, V.; Koníček, J.; Vopálka, D.; Houŝová, D.; Doležalová, L.

    1999-01-01

    The advanced method consists in implantation—labelling of the thin surface layers of the solid objects, e.g. hard tooth tissue, by atoms of suitable natural or artificial radionuclides. Nuclides from the uranium series were implanted into the surface by using nuclear recoil effect at alpha decay of 226Ra to 222Rn, alpha decay of 222Rn to RaA, alpha decay of RaA to RaB (beta-emitter) and further alpha or beta emitters. With regard to chosen alpha detection and to the half—lives of the radionuclides, there was actually measured the activity of 222Rn, RaA and RaC’ in the thin surface layer. This was followed by the laboratory simulation of the abrasion in the system of “toothbrush—various suspensions of the tooth-pastes—hard tooth tissue (or material standard—ivory)” in specially designed device—the dentoabrasionmeter. The activities of the tissue surface measured before and after abrasion were used for calculations of the relative drop of the surface activity. On this basis the influence of various tooth-pastes containing various abrasive substances was determined.

  18. Microstructural and mechanical characteristics of Ni–Cr thin films

    SciTech Connect

    Petley, Vijay; Sathishkumar, S.; Thulasi Raman, K.H.; Rao, G.Mohan; Chandrasekhar, U.

    2015-06-15

    Highlights: • Ni–Cr thin films of varied composition deposited by DC magnetron co-sputtering. • Thin film with Ni–Cr: 80–20 at% composition exhibits most distinct behavior. • The films were tensile tested and exhibited no cracking till the substrate yielding. - Abstract: Ni–Cr alloy thin films have been deposited using magnetron co-sputtering technique at room temperature. Crystal structure was evaluated using GIXRD. Ni–Cr solid solution upto 40 at% of Cr exhibited fcc solid solution of Cr in Ni and beyond that it exhibited bcc solid solution of Ni in Cr. X-ray diffraction analysis shows formation of (1 1 1) fiber texture in fcc and (2 2 0) fiber texture in bcc Ni–Cr thin films. Electron microscopy in both in-plane and transverse direction of the film surface revealed the presence of columnar microstructure for films having Cr upto 40 at%. Mechanical properties of the films are evaluated using nanoindentation. The modulus values increased with increase of Cr at% till the film is fcc. With further increase in Cr at% the modulus values decreased. Ni–Cr film with 20 at% Ni exhibits reduction in modulus and is correlated to the poor crystallization of the film as reflected in XRD analysis. The Ni–Cr thin film with 80 at% Ni and 20 at% Cr exhibited the most distinct columnar structure with highest electrical resistivity, indentation hardness and elastic modulus.

  19. Altering properties of cerium oxide thin films by Rh doping

    SciTech Connect

    Ševčíková, Klára; Nehasil, Václav; Vorokhta, Mykhailo; Haviar, Stanislav; Matolín, Vladimír; and others

    2015-07-15

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO{sub x} thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO{sub x} thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce{sup 4+} and Ce{sup 3+} and rhodium occurs in two oxidation states, Rh{sup 3+} and Rh{sup n+}. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO{sub x} thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO{sub x} thin films leads to preparing materials with different properties.

  20. A Method for Measuring the Hardness of the Surface Layer on Hot Forging Dies Using a Nanoindenter

    NASA Astrophysics Data System (ADS)

    Mencin, P.; van Tyne, C. J.; Levy, B. S.

    2009-11-01

    The properties and characteristics of the surface layer of forging dies are critical for understanding and controlling wear. However, the surface layer is very thin, and appropriate property measurements are difficult to obtain. The objective of the present study is to determine if nanoindenter testing provides a reliable method, which could be used to measure the surface hardness in forging die steels. To test the reliability of nanoindenter testing, nanoindenter values for two quenched and tempered steels (FX and H13) are compared to microhardness and macrohardness values. These steels were heat treated for various times to produce specimens with different values of hardness. The heat-treated specimens were tested using three different instruments—a Rockwell hardness tester for macrohardness, a Vickers hardness tester for microhardness, and a nanoindenter tester for fine scale evaluation of hardness. The results of this study indicate that nanoindenter values obtained using a Nanoindenter XP Machine with a Berkovich indenter reliably correlate with Rockwell C macrohardness values, and with Vickers HV microhardness values. Consequently, nanoindenter testing can provide reliable results for analyzing the surface layer of hot forging dies.

  1. Hard metal lung disease: a case series

    PubMed Central

    Mizutani, Rafael Futoshi; Terra-Filho, Mário; Lima, Evelise; Freitas, Carolina Salim Gonçalves; Chate, Rodrigo Caruso; Kairalla, Ronaldo Adib; Carvalho-Oliveira, Regiani; Santos, Ubiratan Paula

    2016-01-01

    ABSTRACT Objective: To describe diagnostic and treatment aspects of hard metal lung disease (HMLD) and to review the current literature on the topic. Methods: This was a retrospective study based on the medical records of patients treated at the Occupational Respiratory Diseases Clinic of the Instituto do Coração, in the city of São Paulo, Brazil, between 2010 and 2013. Results: Of 320 patients treated during the study period, 5 (1.56%) were diagnosed with HMLD. All of those 5 patients were male (mean age, 42.0 ± 13.6 years; mean duration of exposure to hard metals, 11.4 ± 8.0 years). Occupational histories were taken, after which the patients underwent clinical evaluation, chest HRCT, pulmonary function tests, bronchoscopy, BAL, and lung biopsy. Restrictive lung disease was found in all subjects. The most common chest HRCT finding was ground glass opacities (in 80%). In 4 patients, BALF revealed multinucleated giant cells. In 3 patients, lung biopsy revealed giant cell interstitial pneumonia. One patient was diagnosed with desquamative interstitial pneumonia associated with cellular bronchiolitis, and another was diagnosed with a hypersensitivity pneumonitis pattern. All patients were withdrawn from exposure and treated with corticosteroid. Clinical improvement occurred in 2 patients, whereas the disease progressed in 3. Conclusions: Although HMLD is a rare entity, it should always be included in the differential diagnosis of respiratory dysfunction in workers with a high occupational risk of exposure to hard metal particles. A relevant history (clinical and occupational) accompanied by chest HRCT and BAL findings suggestive of the disease might be sufficient for the diagnosis. PMID:28117477

  2. Assessing mechanical properties from cone indentation hardness

    NASA Astrophysics Data System (ADS)

    Dicarlo, Anthony Albert

    This dissertation investigates methods for assessing the mechanical properties of materials using hardness values obtained from cone indentations. A broad range of isotropic metallic materials was simulated using finite element analysis. In particular, the elastic and plastic bulk properties, which define the stress-strain behavior of materials that exhibit power law hardening, are studied. Other investigators have found that the Young's modulus, E, can be determined from the unloading data of a cone indentation. Therefore, the remaining properties of interest, in this study, are the yield strength, Y, and the work hardening exponent, n. Atkins and Tabor have conducted pioneering work in the area of determining the stress-strain behavior of a metallic material from cone indentation experiments. This work has been re-visited in this study using computational models implementing an expanded range of mechanical properties. Consequently, discrepancies in this prediction method were uncovered when the mechanical properties were outside of the original range studied. As a result, two new prediction methods have been developed using the data collected from the finite element simulations in conjunction with a regression technique. The first method correlates the non-dimensional hardness values, H/E, collected from five cone indentations to the non-dimensional mechanical properties, Y/E and n. The second method is similar in principle, but uses two hardness values as opposed to five. The yield strength can be estimated with a priori knowledge of E. Both of these methods are compared to the method developed by Atkins and Tabor. Although the majority of the work mentioned is focused on the macro-scale, bulk mechanical properties, there is some investigation of meso-scale cone indentations. At the meso-scale, the number of geometric dislocations is significant enough to noticeably increase the strength of a material. This length scale effect is studied for various angled cone

  3. Moral Hard-Wiring and Moral Enhancement.

    PubMed

    Persson, Ingmar; Savulescu, Julian

    2017-03-16

    We have argued for an urgent need for moral bioenhancement; that human moral psychology is limited in its ability to address current existential threats due to the evolutionary function of morality to maximize cooperation in small groups. We address here Powell and Buchanan's novel objection that there is an 'inclusivist anomaly': humans have the capacity to care beyond in-groups. They propose that 'exclusivist' (group-based) morality is sensitive to environmental cues that historically indicated out-group threat. When this is not present, we are inclusivist. They conclude that moral bioenhancement is unnecessary or less effective than socio-cultural interventions. We argue that Powell and Buchanan underestimate the hard-wiring features of moral psychology; their appeal to adaptively plastic, conditionally expressed responses accounts for only a fragment of our moral psychology. In addition to restrictions on our altruistic concern that their account addresses - such as racism and sexism - there are ones it is ill-suited to address: that our concern is stronger for kin and friends and for concrete individuals rather than for statistical lives; also our bias towards the near future. Hard-wired features of our moral psychology that are not clearly restrictions in altruistic concern also include reciprocity, tit-for-tat, and others. Biomedical means are not the only, and maybe not the most important, means of moral enhancement. Socio-cultural means are of great importance and there are currently no biomedical interventions for many hard-wired features. Nevertheless research is desirable because the influence of these features is greater than our critics think.

  4. CO2 laser milling of hard tissue

    NASA Astrophysics Data System (ADS)

    Werner, Martin; Ivanenko, Mikhail; Harbecke, Daniela; Klasing, Manfred; Steigerwald, Hendrik; Hering, Peter

    2007-02-01

    Drilling of bone and tooth tissue belongs to recurrent medical procedures (screw- and pin-bores, bores for implant inserting, trepanation etc.). Small round bores can be in general quickly produced with mechanical drills. Problems arise however by angled drilling, by the necessity to fulfill the drilling without damaging of sensitive soft tissue beneath the bone, or by the attempt to mill precisely noncircular small cavities. We present investigations on laser hard tissue "milling", which can be advantageous for solving these problems. The "milling" is done with a CO2 laser (10.6 μm) with pulse duration of 50 - 100 μs, combined with a PC-controlled galvanic beam scanner and with a fine water-spray, which helps to avoid thermal side-effects. The damaging of underlying soft tissue can be prevented through control of the optical or acoustical ablation signal. The ablation of hard tissue is accompanied with a strong glowing, which is absent during the laser beam action on soft tissue. The acoustic signals from the diverse tissue types exhibit distinct differences in the spectral composition. Also computer image analysis could be a useful tool to control the operation. Laser "milling" of noncircular cavities with 1 - 4 mm width and about 10 mm depth is particularly interesting for dental implantology. In ex-vivo investigations we found conditions for fast laser "milling" of the cavities without thermal damage and with minimal tapering. It included exploration of different filling patterns (concentric rings, crosshatch, parallel lines and their combinations), definition of maximal pulse duration, repetition rate and laser power, optimal position of the spray. The optimized results give evidences for the applicability of the CO2 laser for biologically tolerable "milling" of deep cavities in the hard tissue.

  5. Epitaxial thin films

    DOEpatents

    Hunt, Andrew Tye; Deshpande, Girish; Lin, Wen-Yi; Jan, Tzyy-Jiuan

    2006-04-25

    Epitatial thin films for use as buffer layers for high temperature superconductors, electrolytes in solid oxide fuel cells (SOFC), gas separation membranes or dielectric material in electronic devices, are disclosed. By using CCVD, CACVD or any other suitable deposition process, epitaxial films having pore-free, ideal grain boundaries, and dense structure can be formed. Several different types of materials are disclosed for use as buffer layers in high temperature superconductors. In addition, the use of epitaxial thin films for electrolytes and electrode formation in SOFCs results in densification for pore-free and ideal gain boundary/interface microstructure. Gas separation membranes for the production of oxygen and hydrogen are also disclosed. These semipermeable membranes are formed by high-quality, dense, gas-tight, pinhole free sub-micro scale layers of mixed-conducting oxides on porous ceramic substrates. Epitaxial thin films as dielectric material in capacitors are also taught herein. Capacitors are utilized according to their capacitance values which are dependent on their physical structure and dielectric permittivity. The epitaxial thin films of the current invention form low-loss dielectric layers with extremely high permittivity. This high permittivity allows for the formation of capacitors that can have their capacitance adjusted by applying a DC bias between their electrodes.

  6. Protein thin film machines.

    PubMed

    Federici, Stefania; Oliviero, Giulio; Hamad-Schifferli, Kimberly; Bergese, Paolo

    2010-12-01

    We report the first example of microcantilever beams that are reversibly driven by protein thin film machines fueled by cycling the salt concentration of the surrounding solution. We also show that upon the same salinity stimulus the drive can be completely reversed in its direction by introducing a surface coating ligand. Experimental results are throughout discussed within a general yet simple thermodynamic model.

  7. Treading on Thin Water.

    ERIC Educational Resources Information Center

    Haley, Richard D.

    1985-01-01

    Provides a simple introduction to animals whose habitat is the thin surface film of water. Describes adaptive mechanisms of water striders, whirlygigs and riffle bugs and suggests ways to observe them in the wild or as aquarium animals. Includes basic demonstrations of the nature of surface tension. (JHZ)

  8. Thin Wall Iron Castings

    SciTech Connect

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  9. Thin Lens Ray Tracing.

    ERIC Educational Resources Information Center

    Gatland, Ian R.

    2002-01-01

    Proposes a ray tracing approach to thin lens analysis based on a vector form of Snell's law for paraxial rays as an alternative to the usual approach in introductory physics courses. The ray tracing approach accommodates skew rays and thus provides a complete analysis. (Author/KHR)

  10. Thin film photovoltaic cell

    DOEpatents

    Meakin, John D.; Bragagnolo, Julio

    1982-01-01

    A thin film photovoltaic cell having a transparent electrical contact and an opaque electrical contact with a pair of semiconductors therebetween includes utilizing one of the electrical contacts as a substrate and wherein the inner surface thereof is modified by microroughening while being macro-planar.

  11. Stripe glasses in ferromagnetic thin films

    NASA Astrophysics Data System (ADS)

    Principi, Alessandro; Katsnelson, Mikhail I.

    2016-02-01

    Domain walls in magnetic multilayered systems can exhibit a very complex and fascinating behavior. For example, the magnetization of thin films of hard magnetic materials is in general perpendicular to the thin-film plane, thanks to the strong out-of-plane anisotropy, but its direction changes periodically, forming an alternating spin-up and spin-down stripe pattern. The latter is stabilized by the competition between the ferromagnetic coupling and dipole-dipole interactions, and disappears when a moderate in-plane magnetic field is applied. It has been suggested that such a behavior may be understood in terms of a self-induced stripe glassiness. In this paper we show that such a scenario is compatible with the experimental findings. The strong out-of-plane magnetic anisotropy of the film is found to be beneficial for the formation of both stripe-ordered and glassy phases. At zero magnetic field the system can form a glass only in a narrow interval of fairly large temperatures. An in-plane magnetic field, however, shifts the glass transition towards lower temperatures, therefore enabling it at or below room temperature. In good qualitative agreement with the experimental findings, we show that a moderate in-plane magnetic field of the order of 50 mT can lead to the formation of defects in the stripe pattern, which sets the onset of the glass transition.

  12. Stripe glasses in ferromagnetic thin films

    NASA Astrophysics Data System (ADS)

    Principi, Alessandro; Katsnelson, Mikhail

    Domain walls in magnetic multilayered systems can exhibit a very complex and fascinating behavior. The magnetization of thin films of hard magnetic materials is in general perpendicular to the thin-film plane, but its direction changes periodically, forming an alternating spin-up and spin-down stripe pattern. The latter is stabilized by the competition between the ferromagnetic coupling and dipole-dipole interactions, and disappears when a moderate in-plane magnetic field is applied. It has been suggested that such a behavior may be understood in terms of a self-induced stripe glassiness. In this paper we show that such a scenario is compatible with the experimental findings. The strong out-of-plane magnetic anisotropy of the film is found to be beneficial for the formation of both the stripe-ordered and glassy phases. At zero magnetic field the system can form a glass only in a narrow interval of fairly large temperatures. An in-plane magnetic field, however, shifts the glass transition towards lower temperatures, therefore enabling it at or below room temperature. In good qualitative agreement with the experimental findings, we show that a moderate in-plane magnetic field of the order of 30 mT can lead to the formation of defects in the stripe pattern.

  13. Structuring of thin film solar cells

    NASA Astrophysics Data System (ADS)

    Eberhardt, Gabriele; Banse, Henrik; Wagner, Uwe; Peschel, Thomas

    2010-02-01

    Laser structuring of different types of thin film layers is a state of the art process in the photovoltaic industry. TCO layers and molybdenum are structured with e.g. 1064 nm lasers. Amorphous silicon, microcrystalline silicon or cadmium telluride are ablated with 515/532 nm lasers. Typical pulse durations of the lasers in use for these material ablation processes are in the nanosecond range. Up to now the common process for CIS/CIGS cells is needle structuring. Hard metal needles scribe lines with a width of 30 to 60 μm into the semiconductor material. A laser technology would have some advantages compared to mechanical scribing. The precision of the lines would be higher (no chipping effects), the laser has no wear out. The dead area (distance from P1 structuring line to P3 structuring line) can be significantly smaller with the laser technology. So we investigate the structuring of CIS/CIGS materials with ultra short pulse lasers of different wavelengths. The ablation rates and the structuring speeds versus the repetition rates have been established. For the different layer thicknesses and line widths we determined the necessary energy densities. After all tests we can calculate the possible reduction of the dead area on the thin film module. The new technology will result in an increase in the efficiency per module of up to 4 %.

  14. Second virial coefficients of dipolar hard spheres.

    PubMed

    Philipse, Albert P; Kuipers, Bonny W M

    2010-08-18

    An asymptotic formula is reported for the second virial coefficient B(2) of a dipolar hard-sphere (DHS) fluid, in zero external field, for strongly coupled dipolar interactions. This simple formula, together with the one for the weak-coupling B(2), provides an accurate prediction of the second virial coefficient for a wide range of dipole moments, including those that are experimentally accessible in magnetite ferrofluids. The weak-coupling B(2) also yields an estimate of the magnetic moment minimally needed for isotropic gas-liquid phase-separation, if any, in the DHS fluid.

  15. Hard X Rays from Supernova 1993J

    DTIC Science & Technology

    1994-01-01

    extensively observed at many wavelengths and has yielded a wealth of new information about core - collapse supernovae (Wheeler & Filipenko 1994, and references...modelled as the result of a core collapse and subsequent explosion in a red supergiant that had lost almost all of its hydrogen-rich envelope (Nomoto...HARD X RAYS FROM SUPERNOVA 1993J M.D. Leising1, J.D. Kurfess2, D.D. Clayton1, D.A. Grabelsky3, J.E. Grove2, W.N. Johnson2, G.V. Jung4, R.L. Kinzer2

  16. A case of hard palate perforation

    PubMed Central

    Saroch, Atul; Pannu, Ashok Kumar

    2016-01-01

    Tuberculosis (TB) is a major public health problem in developing countries. Lung is most common affected organ, however extra pulmonary tuberculosis (EPTB) is also not uncommon. The clinical manifestations of EPTB may be non-specific that mimics other diseases and is usually misdiagnosed. Therefore, high clinical suspicion of EPTB infection is important, especially in endemic areas. Here, we present a case of hard palate perforation that proved to be tuberculous in origin. The diagnosis was made by histo-pathological examination and positive TB Polymerase chain reaction (PCR). PMID:28349008

  17. Hard X-ray Laue monochromator

    NASA Astrophysics Data System (ADS)

    Kocharyan, V. R.; Gogolev, A. S.; Kiziridi, A. A.; Batranin, A. V.; Muradyan, T. R.

    2016-06-01

    Experimental studies of X-ray diffraction from reflecting atomic planes (10¯11) of X-cut quartz single crystal in Laue geometry influenced by the temperature gradient were carried out. It is shown that by using the temperature gradient it is possible to reflect a hard X- ray beam with photon energy near the 100 keV with high efficiency. It has been experimentally proved that the intensity of the reflected beam can be increased by more than order depending on the value of the temperature gradient.

  18. Hard gamma ray emission from blazars

    NASA Technical Reports Server (NTRS)

    Marscher, Alan P.; Bloom, Steven D.

    1992-01-01

    The gamma-ray emission expected from compact extragalactic sources of nonthermal radiation is examined. The highly variable objects in this class should produce copious amounts of self-Compton gamma-rays in the compact relativistic jet. This is shown to be a likely interpretation of the hard gamma-ray emission recently detected from the quasar 3C 279 during a period of strong nonthermal flaring at lower frequencies. Ways of discriminating between the self-Compton model and other possible gamma-ray emission mechanisms are discussed.

  19. Hard Exclusive Vector Meson Leptoproduction At HERMES

    SciTech Connect

    Golembiovskaya, M.

    2011-07-15

    The HERMES experiment at DESY, Hamburg collected a set of data on hard exclusive vector meson ({rho}{sup 0}{phi},{omega}) leptoproduction using the 27.6 GeV longitudinally polarized lepton beam of HERA accelerator and longitudinally or transversely polarized or unpolarized gas targets. Measurements of exclusive vector meson production provide access to the structure of the nucleon since the process can be described in terms of Generalized Parton Distributions (GPDs). An overview of the HERMES results on exclusive vector mesons production is presented.

  20. Arching in tapped deposits of hard disks.

    PubMed

    Pugnaloni, Luis A; Valluzzi, Marcos G; Valluzzi, Lucas G

    2006-05-01

    We simulate the tapping of a bed of hard disks in a rectangular box by using a pseudodynamic algorithm. In these simulations, arches are unambiguously defined and we can analyze their properties as a function of the tapping amplitude. We find that an order-disorder transition occurs within a narrow range of tapping amplitudes as has been seen by others. Arches are always present in the system although they exhibit regular shapes in the ordered regime. Interestingly, an increase in the number of arches does not always correspond to a reduction in the packing fraction. This is in contrast with what is found in three-dimensional systems.

  1. Superferrimagnetism in hard Nd-Fe-B thick films, an original concept for coercivity enhancement

    NASA Astrophysics Data System (ADS)

    Akdogan, O.; Dobrynin, A.; Le Roy, D.; Dempsey, N. M.; Givord, D.

    2014-05-01

    In a number of applications (automotive, wind generators), RFeB magnets are parts of systems which operate at temperatures in the range of 160 °C-180 °C. At these high temperatures, coercivity is preserved by substituting Dy atoms for a part of the Nd ones. The enhanced coercivity obtained may be associated to the high magnetocrystalline anisotropy of Dy atoms, which diffuse into the R2Fe14B phase. The introduction of Dy, however, induces a reduction in the remanent magnetization. Furthermore, Dy is an expensive and strategic material. In this study, we explore a radically different approach to coercivity. A magnetic layer is deposited at the surface of the hard grains, this layer being exchange coupled to the main hard phase in a way that its magnetization is antiparallel to it. Under an applied field that tends to reverse the main phase magnetization, the surface layer, the magnetization of which is along the field, works against reversal. This is the concept of superferrimagnetism. In order to test its impact on the coercivity of real systems, magnetically hard thick films of NdFeB have been sandwiched between thin layers of Gd/Fe, which were transformed to GdFe2 upon annealing. Coercivity enhancement was achieved compared to a reference NdFeB single layer.

  2. Hard Burst Emission from the Soft Gamma Repeater SGR 1900+14

    NASA Technical Reports Server (NTRS)

    Woods, Peter M.; Kouveliotou, Chryssa; VanParadijs, Jan; Briggs, Michael S.; Hurley, Kevin; Gogus, Ersin; Preece, Robert D.; Giblin, Timothy W.; Thompson, Christopher; Duncan, Robert C.

    1999-01-01

    We present evidence for burst emission from SGR 1900 + 14 with a power-law high-energy spectrum extending beyond 500 keV. Unlike previous detections of high-energy photons during bursts from soft gamma repeaters (SGRs), these emissions are not associated with extraordinarily bright flares. Not only is the emission hard, but the spectra are better fitted by D. Band's gamma-ray burst (GRB) function rather than by the traditional optically thin thermal bremsstrahlung model. We find that the spectral evolution within these hard events obeys a hardness/intensity anticorrelation. Temporally, these events are distinct from typical SGR burst emissions in that they are longer (approximately 1 s) and have relatively smooth profiles. Despite a difference in peak luminosity of approximately > 10(exp 11) between these bursts from SGR 1900 + 14 and cosmological GRBs, there are striking temporal and spectral similarities between the two kinds of bursts, aside from spectral evolution. We outline an interpretation of these events in the context of the magnetar model.

  3. Performance of ASTRO-H hard x-ray telescope (HXT)

    NASA Astrophysics Data System (ADS)

    Awaki, Hisamitsu; Kunieda, Hideyo; Ishida, Manabu; Matsumoto, Hironori; Furuzawa, Akihiro; Haba, Yoshito; Hayashi, Takayuki; Iizuka, Ryo; Ishibashi, Kazunori; Itoh, Masayuki; Kosaka, Tatsuro; Maeda, Yoshitomo; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mori, Hideyuki; Nagano, Hosei; Namba, Yoshiharu; Ogasaka, Yasushi; Ogi, Keiji; Okajima, Takashi; Sugita, Satoshi; Suzuki, Yoshio; Tamura, Keisuke; Tawara, Yuzuru; Uesugi, Kentaro; Yamauchi, Shigeo

    2016-07-01

    The Japanese X-ray Astronomy Satellite, Hitomi (ASTRO-H) carries hard X-ray imaging system, covering the energy band from 5 keV to 80 keV. The hard X-ray imaging system consists of two hard X-ray telescopes (HXT) and the focal plane detectors (HXI). The HXT employs tightly-nested, conically-approximated thin foil Wolter-I optics. The mirror surfaces of HXT were coated with Pt/C depth-graded multilayers. We carried out ground calibrations of HXTs at the synchrotron radiation facility SPring-8/ BL20B2 Japan, and found that total effective area of two HXTs was about 350 cm2 at 30 keV, and the half power diameter of HXT was about 1.'9. After the launch of Hitomi, Hitomi observed several targets during the initial functional verification of the onboard instruments. The Hitomi software and calibration team (SCT) provided the Hitomi's data of G21.5-0.9, a pulsar wind nebula, to the hardware team for the purpose of the instrument calibration. Through the analysis of the in-flight data, we have confirmed that the X-ray performance of HXTs in orbit was consistent with that obtained by the ground calibrations.

  4. Hard Burst Emission from the Soft Gamma Repeater SGR 1900+14

    NASA Technical Reports Server (NTRS)

    Duncan, Robert D.; Kouveliotou, Chryssa; vanParadijs, Jan; Briggs, Michael S.; Hurley, Kevin; Gogus, Ersin; Preece, Robert D.; Giblin, Timothy W.; Thompson, Christopher; Duncan, Robert C.

    1999-01-01

    We present evidence for burst emission from SGR 1900+14 with a power-law high energy spectrum extending beyond 500 kev. Unlike previous detections of high energy photons during bursts from SGRS, these emissions are not associated with high-luminosity burst intervals. Not only is the emission hard, but the spectra are better fit by Band's GRB function rather than by the traditional optically-thin thermal bremsstrahlung model. We find that the spectral evolution within these hard events obeys a hardness/intensity anti-correlation. Temporally, these events are distinct from typical SGR burst emissions in that they are longer (about 1 s) and have relatively smooth profiles. Despite a difference in peak luminosity of > 1E+ll between these bursts from SGR 1900+14 and cosmological GRBS, there are striking temporal and spectral similarities between the two kinds of bursts, aside from spectral evolution. We outline an interpretation of these events in the context of the magnetar model.

  5. Direct-write X-ray lithography using a hard X-ray Fresnel zone plate.

    PubMed

    Lee, Su Yong; Noh, Do Young; Lee, Hae Cheol; Yu, Chung-Jong; Hwu, Yeukuang; Kang, Hyon Chol

    2015-05-01

    Results are reported of direct-write X-ray lithography using a hard X-ray beam focused by a Fresnel zone plate with an outermost zone width of 40 nm. An X-ray beam at 7.5 keV focused to a nano-spot was employed to write arbitrary patterns on a photoresist thin film with a resolution better than 25 nm. The resulting pattern dimension depended significantly on the kind of underlying substrate, which was attributed to the lateral spread of electrons generated during X-ray irradiation. The proximity effect originated from the diffuse scattering near the focus and electron blur was also observed, which led to an increase in pattern dimension. Since focusing hard X-rays to below a 10 nm spot is currently available, the direct-write hard X-ray lithography developed in this work has the potential to be a promising future lithographic method.

  6. Thin film solar cell workshop

    NASA Technical Reports Server (NTRS)

    Armstrong, Joe; Jeffrey, Frank

    1993-01-01

    A summation of responses to questions posed to the thin-film solar cell workshop and the ensuing discussion is provided. Participants in the workshop included photovoltaic manufacturers (both thin film and crystalline), cell performance investigators, and consumers.

  7. Thin films for material engineering

    NASA Astrophysics Data System (ADS)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  8. Hardness of irradiated poly(methyl methacrylate) at elevated temperatures

    SciTech Connect

    Lu, K.-P.; Lee, Sanboh; Cheng, Cheu Pyeng

    2001-08-15

    The decrease in hardness induced by gamma irradiation in poly(methyl methacrylate) (PMMA) has been investigated. The hardness is assumed to decrease linearly with the concentration of radiation-induced defects. Annealing at high temperatures induces defect annihilation as tracked by an increase in hardness. The annihilation follows first-order kinetics during isothermal annealing. The dependence of hardness on the reciprocal of the time constant satisfies the Arrhenius equation, and the corresponding activation energy of the kinetic process decreases with increasing dose. The hardness of postannealed PMMA decreases linearly with increasing dose. {copyright} 2001 American Institute of Physics.

  9. NMR characterization of thin films

    DOEpatents

    Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2010-06-15

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  10. VACUUM DEPOSITION OF THIN FILMS,

    DTIC Science & Technology

    The book deals with methods of obtaining and processing thin films , methods of measuring the deposition rate and thickness of thin-film layers, and...the main fields of application of thin films . Vacuum requirements and the requirements for the composition of the residual medium in thermal...evaporation and cathode sputtering are given, and modern methods of producing and measuring vacuums and the equipment used in obtaining thin films are described. (Author)

  11. Wind, jet, hybrid corona and hard X-ray flares: multiwavelength evolution of GRO J1655-40 during the 2005 outburst rise

    NASA Astrophysics Data System (ADS)

    Kalemci, E.; Begelman, M. C.; Maccarone, T. J.; Dinçer, T.; Russell, T. D.; Bailyn, C.; Tomsick, J. A.

    2016-11-01

    We have investigated the complex multiwavelength evolution of GRO J1655-40 during the rise of its 2005 outburst. We detected two hard X-ray flares, the first one during the transition from the soft state to the ultra-soft state, and the second one in the ultra-soft state. The first X-ray flare coincided with an optically thin radio flare. We also observed a hint of increased radio emission during the second X-ray flare. To explain the hard flares without invoking a secondary emission component, we fit the entire data set with the eqpair model. This single, hybrid Comptonization model sufficiently fits the data even during the hard X-ray flares if we allow reflection fractions greater than unity. In this case, the hard X-ray flares correspond to a Comptonizing corona dominated by non-thermal electrons. The fits also require absorption features in the soft and ultra-soft state which are likely due to a wind. In this work we show that the wind and the optically thin radio flare co-exist. Finally, we have also investigated the radio to optical spectral energy distribution, tracking the radio spectral evolution through the quenching of the compact jet and rise of the optically thin flare, and interpreted all data using state transition models.

  12. Influence of Gene Expression on Hardness in Wheat.

    PubMed

    Nirmal, Ravi C; Furtado, Agnelo; Wrigley, Colin; Henry, Robert J

    2016-01-01

    Puroindoline (Pina and Pinb) genes control grain texture or hardness in wheat. Wild-type/soft alleles lead to softer grain while a mutation in one or both of these genes results in a hard grain. Variation in hardness in genotypes with identical Pin alleles (wild-type or mutant) is known but the molecular basis of this is not known. We now report the identification of wheat genotypes with hard grain texture and wild-type/soft Pin alleles indicating that hardness in wheat may be controlled by factors other than mutations in the coding region of the Pin genes. RNA-Seq analysis was used to determine the variation in the transcriptome of developing grains of thirty three diverse wheat genotypes including hard (mutant Pin) and soft (wild type) and those that were hard without having Pin mutations. This defined the role of pin gene expression and identified other candidate genes associated with hardness. Pina was not expressed in hard wheat with a mutation in the Pina gene. The ratio of Pina to Pinb expression was generally lower in the hard non mutant genotypes. Hardness may be associated with differences in Pin expression and other factors and is not simply associated with mutations in the PIN protein coding sequences.

  13. Influence of Gene Expression on Hardness in Wheat

    PubMed Central

    Nirmal, Ravi C.; Wrigley, Colin

    2016-01-01

    Puroindoline (Pina and Pinb) genes control grain texture or hardness in wheat. Wild-type/soft alleles lead to softer grain while a mutation in one or both of these genes results in a hard grain. Variation in hardness in genotypes with identical Pin alleles (wild-type or mutant) is known but the molecular basis of this is not known. We now report the identification of wheat genotypes with hard grain texture and wild-type/soft Pin alleles indicating that hardness in wheat may be controlled by factors other than mutations in the coding region of the Pin genes. RNA-Seq analysis was used to determine the variation in the transcriptome of developing grains of thirty three diverse wheat genotypes including hard (mutant Pin) and soft (wild type) and those that were hard without having Pin mutations. This defined the role of pin gene expression and identified other candidate genes associated with hardness. Pina was not expressed in hard wheat with a mutation in the Pina gene. The ratio of Pina to Pinb expression was generally lower in the hard non mutant genotypes. Hardness may be associated with differences in Pin expression and other factors and is not simply associated with mutations in the PIN protein coding sequences. PMID:27741295

  14. A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids.

    PubMed

    Dai, Fu-Zhi; Zhou, Yanchun

    2016-09-08

    Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials.

  15. A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids

    PubMed Central

    Dai, Fu-Zhi; Zhou, Yanchun

    2016-01-01

    Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials. PMID:27604165

  16. Structures and Properties of C-Doped NiCr Thin Film Deposited by Closed-Field Unbalanced Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Lai, Lifei; Wang, Jinxia; Wang, Hongtao; Bao, Mingdong

    2017-01-01

    The structures and properties of C-doped NiCr thin film as embedded thin film resistor (ETFR) materials were studied by closed-field, unbalanced magnetron sputtering method. The C-doped NiCr (NiCrC1) thin film had more stable electrical performance, better corrosion resistance, and higher hardness than NiCr thin film. The temperature coefficient of resistance (TCR) of NiCrC1 thin film deposited at room temperature (from 19.73 ppm/K to 173.7 ppm/K) was lower than that of NiCr thin film (from 157.8 ppm/K to 378.9 ppm/K), and the sheet resistor (154.25 Ω/Sq) was higher than that of NiCr thin film (62.84 Ω/Sq). The preferred orientations of C-doped NiCr thin film was Ni (111), while that of NiCr thin film was Ni (011). The carbon-doped NiCr thin film can reduce the defects and stress and change the preferred orientations. The dominant carbon in C-doped NiCr thin film had a graphite-like structure.

  17. Hard Carbon Films Deposited under Various Atmospheres

    NASA Astrophysics Data System (ADS)

    Wei, M.-K.; Chen, S.-C.; Wu, T. C.; Lee, Sanboh

    1998-03-01

    Using a carbon target ablated with an XeCl-excimer laser under various gas atmospheres at different pressures, hard carbon was deposited on silicon, iron and tungsten carbide substrates. The hardness, friction coefficient, and wear rate of the film against steel are better than pure substrate material, respectively, so that it has potential to be used as a protective coating for micromechanical elements. The influences of gas pressure, gas atmosphere, and power density of laser irradiation on the thermal stability of film were analyzed by means of Raman-spectroscope, time-of-flight method, and optical emission spectrum. It was found that the film deposited under higher pressure has less diamond-like character. The film deposited under rest gas or argon atmosphere was very unstable and looked like a little graphite-like character. The film deposited at high vacuum (10-5 mbar rest gas) was the most stable and looked like the most diamond-like character. The film deposited at higher power density was more diamond-like than that at lower power density.

  18. Ordering of hard rectangles in strong confinement.

    PubMed

    Gurin, Péter; Varga, Szabolcs; González-Pinto, Miguel; Martínez-Ratón, Yuri; Velasco, Enrique

    2017-04-07

    Using transfer operator and fundamental measure theories, we examine the structural and thermodynamic properties of hard rectangles confined between two parallel hard walls. The side lengths of the rectangle (L and D, L>D) and the pore width (H) are chosen such that a maximum of two layers is allowed to form when the long sides of the rectangles are parallel to the wall, while only one layer is possible in case the rectangles are perpendicular to the wall. We observe three different structures: (i) at low density, the rectangles align mainly parallel to the wall, (ii) at intermediate or high density, two fluid layers form in which the rectangles are parallel to the wall, and (iii) a dense single fluid layer with rectangles aligned mainly perpendicular to the wall. The transition between these structures is smooth without any non-analytic behaviour in the thermodynamic quantities; however, the fraction of particles perpendicular (or parallel) to the wall can exhibit a relatively sudden change if L is close to H. In this case, interestingly, even three different structures can be observed with increasing density.

  19. Equiatomic CoPt thin films with extremely high coercivity

    SciTech Connect

    Varghese, Binni; Piramanayagam, S. N. Yang, Yi; Kai Wong, Seng; Khume Tan, Hang; Kiat Lee, Wee; Okamoto, Iwao

    2014-05-07

    In this paper, magnetic and structural properties of near-equiatomic CoPt thin films, which exhibited a high coercivity in the film-normal direction—suitable for perpendicular magnetic recording media applications—are reported. The films exhibited a larger coercivity of about 6.5 kOe at 8 nm. The coercivity showed a monotonous decrease as the film thickness was increased. The transmission electron microscopy images indicated that the as fabricated CoPt film generally consists of a stack of magnetically hard hexagonal-close-packed phase, followed by stacking faults and face-centred-cubic phase. The thickness dependent magnetic properties are explained on the basis of exchange-coupled composite media. Epitaxial growth on Ru layers is a possible factor leading to the unusual observation of magnetically hard hcp-phase at high concentrations of Pt.

  20. Initial Hardness Response and Hardness Profiles in the Study of Woodward-Hoffmann Rules for Electrocyclizations.

    PubMed

    De Proft, F; Chattaraj, P K; Ayers, P W; Torrent-Sucarrat, M; Elango, M; Subramanian, V; Giri, S; Geerlings, P

    2008-04-01

    The fundamental principles of pericyclic reactions are governed by the Woodward-Hoffmann rules, which state that these reactions can only take place if the symmetries of the reactants' molecular orbitals and the products' molecular orbitals are the same. As such, these rules rely on the nodal structure of either the wave function or the frontier molecular orbitals, so it is unclear how these rules can be recovered in the density functional reactivity theory (or "conceptual DFT"), where the basic quantity is the strictly positive electron density. A third, nonsymmetry based approach to predict the outcome of pericyclic reactions is due to Zimmerman which uses the concept of the aromatic transition states: allowed reactions possess aromatic transition states, while forbidden reactions possess antiaromatic transition states. Based on our recent work on cycloadditions, we investigate the initial response of the chemical hardness, a central DFT based reactivity index, along the reaction profiles of a series of electrocyclizations. For a number of cases, we also compute complete initial reaction coordinate (IRC) paths and hardness profiles. We find that the hardness response is always higher for the allowed modes than for the forbidden modes. This suggests that the initial hardness response along the IRC is the key for casting the Woodward-Hoffmann rules into conceptual DFT.

  1. Fractions, Decimals, Ratios, & Percents: Hard To Teach and Hard To Learn? Mathematics Teaching Cases.

    ERIC Educational Resources Information Center

    Barnett, Carne, Ed.; And Others

    This book presents teacher-written cases relating stories, insights, and experiences about the teaching of fractions, decimals, ratios, and percents. The cases were written to stimulate colleagues to examine their own practice, to think hard about the mathematics they teach and would like to teach, and to initiate inquiries and discussions that…

  2. Phase transition induced by a shock wave in hard-sphere and hard-disk systems.

    PubMed

    Zhao, Nanrong; Sugiyama, Masaru; Ruggeri, Tommaso

    2008-08-07

    Dynamic phase transition induced by a shock wave in hard-sphere and hard-disk systems is studied on the basis of the system of Euler equations with caloric and thermal equations of state. First, Rankine-Hugoniot conditions are analyzed. The quantitative classification of Hugoniot types in terms of the thermodynamic quantities of the unperturbed state (the state before a shock wave) and the shock strength is made. Especially Hugoniot in typical two possible cases (P-1 and P-2) of the phase transition is analyzed in detail. In the case P-1 the phase transition occurs between a metastable liquid state and a stable solid state, and in the case P-2 the phase transition occurs through coexistence states, when the shock strength changes. Second, the admissibility of the two cases is discussed from a viewpoint of the recent mathematical theory of shock waves, and a rule with the use of the maximum entropy production rate is proposed as the rule for selecting the most probable one among the possible cases, that is, the most suitable constitutive equation that predicts the most probable shock wave. According to the rule, the constitutive equation in the case P-2 is the most promising one in the dynamic phase transition. It is emphasized that hard-sphere and hard-disk systems are suitable reference systems for studying shock wave phenomena including the shock-induced phase transition in more realistic condensed matters.

  3. Hard-Boiled for Hard Times in Leonardo Padura Fuentes's Detective Fiction

    ERIC Educational Resources Information Center

    Song, H. Rosi

    2009-01-01

    Focusing on Leonardo Padura Fuentes's hard-boiled fiction, this essay traces the origin and evolution of the genre in Cuba. Padura Fuentes has challenged the officially sanctioned socialist "literatura policial" that became popular in the 1970s and 1980s. creating a new model of criticism that is not afraid to confront the island's socio-economic…

  4. Ultra-hard amorphous AlMgB14 films RF sputtered onto curved substrates

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Putrolaynen, V. V.; Yuzvyuk, M. H.

    2017-03-01

    Recently, hard AlMgB14 (BAM) coatings were deposited for the first time by RF magnetron sputtering using a single stoichiometric ceramic target. High target sputtering power and sufficiently short target-to-substrate distance were found to be critical processing conditions. They enabled fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young’s modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 GPa and 275 GPa at 200 nm depth in 2 µm thick film (Grishin et al 2014 JETP Lett. 100 680). The narrow range of sufficiently short target-to-substrate distance makes impossible to coat non flat specimens. To achieve ultimate BAM films’ characteristics onto curved surfaces we developed two-step sputtering process. The first thin layer is deposited as a template at low RF power that facilitates a layered Frank van der Merwe mode growth of smooth film occurs. The next layer is grown at high RF target sputtering power. The affinity of subsequent flow of sputtered atoms to already evenly condensed template fosters the development of smooth film surface. As an example, we made BAM coating onto hemispherical 5 mm in diameter ball made from a hard tool steel and used as a head of a special gauge. Very smooth (6.6 nm RMS surface roughness) and hard AlMgB14 films fabricated onto commercial ball-shaped items enhance hardness of tool steel specimens by a factor of four.

  5. Advanced thin film thermocouples

    NASA Technical Reports Server (NTRS)

    Kreider, K. G.; Semancik, S.; Olson, C.

    1984-01-01

    The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3.

  6. Shear-thinning Fluid

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Whipped cream and the filling for pumpkin pie are two familiar materials that exhibit the shear-thinning effect seen in a range of industrial applications. It is thick enough to stand on its own atop a piece of pie, yet flows readily when pushed through a tube. This demonstrates the shear-thinning effect that was studied with the Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002. CVX observed the behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The principal investigator was Dr. Robert Berg of the National Institutes of Standards and Technology in Gaithersburg, MD.

  7. Thin film superconductor magnetic bearings

    DOEpatents

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  8. Islands stretch test for measuring the interfacial fracture energy between a hard film and a soft substrate

    NASA Astrophysics Data System (ADS)

    Sun, Jeong-Yun; Lu, Nanshu; Oh, Kyu-Hwan; Suo, Zhigang; Vlassak, Joost J.

    2013-06-01

    We present a technique for measuring the interfacial fracture energy, Γi, between a hard thin film and a soft substrate. A periodic array of hard thin islands is fabricated on a soft substrate, which is then subjected to uniaxial tension under an optical microscope. When the applied strain reaches a critical value, delamination between the islands and the substrate starts from the edge of the islands. As the strain is increased, the interfacial cracks grow in a stable fashion. At a given applied strain, the width of the delaminated region is a unique function of the interfacial fracture energy. We have calculated the energy release rate driving the delamination as a function of delamination width, island size, island thickness, and applied strain. For a given materials system, this relationship allows determination of the interfacial fracture energy from a measurement of the delamination width. The technique is demonstrated by measuring the interfacial fracture energy of plasma-enhanced chemical vapor deposition SiNx islands on a polyimide substrate. We anticipate that this technique will find application in the flexible electronics industry where hard islands on soft substrates are a common architecture to protect active devices from fracture.

  9. Islands stretch test for measuring the interfacial fracture energy between a hard film and a soft substrate

    SciTech Connect

    Sun, Jeong-Yun; Lu, Nanshu; Oh, Kyu-Hwan; Suo, Zhigang; Vlassak, Joost J.

    2013-06-14

    We present a technique for measuring the interfacial fracture energy, {Gamma}{sub i}, between a hard thin film and a soft substrate. A periodic array of hard thin islands is fabricated on a soft substrate, which is then subjected to uniaxial tension under an optical microscope. When the applied strain reaches a critical value, delamination between the islands and the substrate starts from the edge of the islands. As the strain is increased, the interfacial cracks grow in a stable fashion. At a given applied strain, the width of the delaminated region is a unique function of the interfacial fracture energy. We have calculated the energy release rate driving the delamination as a function of delamination width, island size, island thickness, and applied strain. For a given materials system, this relationship allows determination of the interfacial fracture energy from a measurement of the delamination width. The technique is demonstrated by measuring the interfacial fracture energy of plasma-enhanced chemical vapor deposition SiN{sub x} islands on a polyimide substrate. We anticipate that this technique will find application in the flexible electronics industry where hard islands on soft substrates are a common architecture to protect active devices from fracture.

  10. Thin, Lightweight Solar Cell

    NASA Technical Reports Server (NTRS)

    Brandhorst, Henry W., Jr.; Weinberg, Irving

    1991-01-01

    Improved design for thin, lightweight solar photovoltaic cells with front contacts reduces degradation of electrical output under exposure to energetic charged particles (protons and electrons). Increases ability of cells to maintain structural integrity under exposure to ultraviolet radiation by eliminating ultraviolet-degradable adhesives used to retain cover glasses. Interdigitated front contacts and front junctions formed on semiconductor substrate. Mating contacts formed on back surface of cover glass. Cover glass and substrate electrostatically bonded together.

  11. Thin film composite electrolyte

    DOEpatents

    Schucker, Robert C.

    2007-08-14

    The invention is a thin film composite solid (and a means for making such) suitable for use as an electrolyte, having a first layer of a dense, non-porous conductive material; a second layer of a porous ionic conductive material; and a third layer of a dense non-porous conductive material, wherein the second layer has a Coefficient of thermal expansion within 5% of the coefficient of thermal expansion of the first and third layers.

  12. Carbon Nitride Thin Films Deposited by Cathodic Electrodeposition

    NASA Astrophysics Data System (ADS)

    Cao, Chuanbao; Fu, Jiyu; Zhu, Hesun

    Carbon nitride thin films were prepared by cathodic electrodeposition. The dicyandiamide compound dissovled in acetone was selected as the organic precursor. Single crystal silicon wafers and conductive glass (ITO) wafers were used as substrates. XPS measurements indicated that the films composed of carbon and nitrogen elements. The nitrogen content reached 41%. The polycrystalline β-C3N4 should exit in the prepared film from TED measurements. The nano hardness of the films on ITO substrates were as high as 13 GPa. The structure and properties were studies.

  13. Preparation of (001)-oriented Pb(Zr,Ti)O3 thin films and their piezoelectric applications.

    PubMed

    Fujii, Eiji; Takayama, Ryoichi; Nomura, Kouji; Murata, Akiko; Hirasawa, Taku; Tomozawa, Atsushi; Fujii, Satoru; Kamada, Takeshi; Torii, Hideo

    2007-12-01

    Preparation of (001)-oriented Pb(Zr,Ti)O(3) (PZT) thin films and their applications to a sensor and actuators were investigated. These thin films, which have a composition close to the morphotropic phase boundary, were epitaxially grown on (100)MgO single-crystal substrates by RF magnetron sputtering. These (001)-oriented PZT thin films could be obtained on various kinds of substrates, such as glass and Si, by introducing (100)-oriented MgO buffer layers. In addition, the (001) oriented PZT thin films could be obtained on Si substrates without buffer layers by optimizing the sputtering conditions. All of these thin films showed excellent piezoelectric properties without the need for poling treatment. The PZT thin films on the MgO substrates had a high piezoelectric coefficient, d(31), of -100 pm/V, and an extremely low relative dielectric constant, epsilon(r), of 240. The PZT thin films on Si substrate had a very high d(31) of -150 pm/V and an epsilon(r) = 700. These PZT thin films were applied to an angular rate sensor with a tuning fork in a car navigation system, to a dual-stage actuator for positioning the magnetic head of a high-density hard disk drive, and to an actuator for an inkjet printer head for industrial on-demand printers.

  14. Radiation Hardness Assurance (RHA) for Space Systems

    NASA Technical Reports Server (NTRS)

    Poivey, Christian; Buchner, Stephen

    2007-01-01

    This presentation discusses radiation hardness assurance (RHA) for space systems, providing both the programmatic aspects of RHA and the RHA procedure. RHA consists of all activities undertaken to ensure that the electronics and materials of a space system perform to their design specifications after exposure to the space radiation environment. RHA also pertains to environment definition, part selection, part testing, spacecraft layout, radiation tolerant design, and mission/system/subsystems requirements. RHA procedure consists of establishing mission requirements, defining and evaluating the radiation hazard, selecting and categorizing the appropriate parts, and evaluating circuit response to hazard. The RHA approach is based on risk management and is confined only to parts, it includes spacecraft layout, system/subsystem/circuit design, and system requirements and system operations. RHA should be taken into account in the early phases of a program including the proposal and feasibility analysis phases.

  15. Blazars in Hard X-rays

    NASA Astrophysics Data System (ADS)

    Ghisellini, Gabriele

    2009-05-01

    Although blazars are thought to emit most of their luminosity in the γ-ray band, there are subclasses of them very prominent in hard X-rays. These are the best candidates to be studied by Simbol-X. They are at the extremes of the blazar sequence, having very small or very high jet powers. The former are the class of TeV emitting BL Lacs, whose synchrotron emission often peaks at tens of keV or more. The latter are the blazars with the most powerful jets, have high black hole masses accreting at high (i.e. close to Eddington) rates. These sources are predicted to have their high energy peak even below the MeV band, and therefore are very promising candidates to be studied with Simbol-X.

  16. Equilibrium Phase Behavior of Polydisperse Hard Spheres

    NASA Astrophysics Data System (ADS)

    Fasolo, Moreno; Sollich, Peter

    2003-08-01

    We calculate the phase behavior of hard spheres with size polydispersity, using accurate free energies for the fluid and solid phases. Cloud and shadow curves are found exactly by the moment free energy method, but we also compute the complete phase diagram, taking full account of fractionation. In contrast to earlier, simplified treatments we find no point of equal concentration between fluid and solid or reentrant melting at higher densities. Rather, the fluid cloud curve continues to the largest polydispersity that we study (14%); from the equilibrium phase behavior a terminal polydispersity can thus be defined only for the solid, where we find it to be around 7%. At sufficiently large polydispersity, fractionation into several solid phases can occur, consistent with previous approximate calculations; we find, in addition, that coexistence of several solids with a fluid phase is also possible.

  17. Hard sphere study of condensation entropy

    NASA Astrophysics Data System (ADS)

    Graziano, Giuseppe

    2008-06-01

    A simple procedure is devised to calculate the Ben-Naim standard condensation entropy by treating neat liquids as hard sphere fluids. The calculated values are close to the experimental ones for nonpolar liquids, but not for polar aprotic ones and for H-bonded liquids. For the latter the calculated entropy values become close to the experimental ones if the molecular van der Waals diameters are used instead of the effective ones. This implies that the magnitude of the orientational entropy loss due to H-bond formation is quantitatively similar to that of the configurational entropy gain for the decrease in excluded volume due to the bunching up effect caused by H-bonds.

  18. Hard turning micro-machine tool

    SciTech Connect

    DeVor, Richard E; Adair, Kurt; Kapoor, Shiv G

    2013-10-22

    A micro-scale apparatus for supporting a tool for hard turning comprises a base, a pivot coupled to the base, an actuator coupled to the base, and at least one member coupled to the actuator at one end and rotatably coupled to the pivot at another end. A tool mount is disposed on the at least one member. The at least one member defines a first lever arm between the pivot and the tool mount, and a second lever arm between the pivot and the actuator. The first lever arm has a length that is less than a length of the second lever arm. The actuator moves the tool mount along an arc.

  19. Using Cell Phone Keyboards Is (NP) Hard

    NASA Astrophysics Data System (ADS)

    Boothe, Peter

    Sending text messages on cell phones which only contain the keys 0 through 9 and # and * can be a painful experience. We consider the problem of designing an optimal mapping of numbers to sets of letters to act as an alternative to the standard {2→{abc}, 3→{def}...}. Our overall goal is to minimize the expected number of buttons that must be pressed to enter a message in English. Some variations of the problem are efficiently solvable, either by being small instances or by being in P, but the most realistic version of the problem is NP hard. To prove NP-completeness, we describe a new graph coloring problem UniquePathColoring. We also provide numerical results for the English language on a standard corpus which describe several mappings that improve upon the standard one. With luck, one of these new mappings will achieve success similar to that of the Dvorak layout for computer keyboards.

  20. Crystal nucleation of colloidal hard dumbbells.

    PubMed

    Ni, Ran; Dijkstra, Marjolein

    2011-01-21

    Using computer simulations, we investigate the homogeneous crystal nucleation in suspensions of colloidal hard dumbbells. The free energy barriers are determined by Monte Carlo simulations using the umbrella sampling technique. We calculate the nucleation rates for the plastic crystal and the aperiodic crystal phase using the kinetic prefactor as determined from event driven molecular dynamics simulations. We find good agreement with the nucleation rates determined from spontaneous nucleation events observed in event driven molecular dynamics simulations within error bars of one order of magnitude. We study the effect of aspect ratio of the dumbbells on the nucleation of plastic and aperiodic crystal phases, and we also determine the structure of the critical nuclei. Moreover, we find that the nucleation of the aligned close-packed crystal structure is strongly suppressed by a high free energy barrier at low supersaturations and slow dynamics at high supersaturations.

  1. Shock compression synthesis of hard materials

    SciTech Connect

    Willson, C.G.

    1999-03-01

    The purpose of this research was to adapt the high explosives technology that was developed in conjunction with nuclear weapons programs to subjecting materials to ultra-high pressures and to explore the utility of this technique for the synthesis of hard materials. The research was conducted in collaboration with researchers at the University of Texas, Texas Tech University and Pantex (Mason and Hanger Corp.). The group designed, modeled, built, and tested a new device that allows quantitative recovery of grams of material that have been subjected to unprecedented pressures. The modeling work was done at Texas Tech and Pantex. The metal parts and material samples were made at the University of Texas, and Pantex machined the explosives, assembled the devices and conducted the detonations. Sample characterization was carried out at the University of Texas and Texas Tech.

  2. Coendangered hard-ticks: threatened or threatening?

    PubMed Central

    2011-01-01

    The overwhelming majority of animal conservation projects are focused on vertebrates, despite most of the species on Earth being invertebrates. Estimates state that about half of all named species of invertebrates are parasitic in at least one stage of their development. The dilemma of viewing parasites as biodiversity or pest has been discussed by several authors. However, ticks were omitted. The latest taxonomic synopses of non-fossil Ixodidae consider valid 700 species. Though, how many of them are still extant is almost impossible to tell, as many of them are known only from type specimens in museums and were never collected since their original description. Moreover, many hosts are endangered and as part of conservation efforts of threatened vertebrates, a common practice is the removal of, and treatment for external parasites, with devastating impact on tick populations. There are several known cases when the host became extinct with subsequent coextinction of their ectoparasites. For our synoptic approach we have used the IUCN status of the host in order to evaluate the status of specifically associated hard-ticks. As a result, we propose a number of 63 coendangered and one extinct hard-tick species. On the other side of the coin, the most important issue regarding tick-host associations is vectorial transmission of microbial pathogens (i.e. viruses, bacteria, protozoans). Tick-borne diseases of threatened vertebrates are sometimes fatal to their hosts. Mortality associated with pathogens acquired from ticks has been documented in several cases, mostly after translocations. Are ticks a real threat to their coendangered host and should they be eliminated? Up to date, there are no reliable proofs that ticks listed by us as coendangered are competent vectors for pathogens of endangered animals. PMID:21554736

  3. TOPOGRAPHIC SITE RESPONSE AT HARD ROCK SITES

    NASA Astrophysics Data System (ADS)

    Yong, A. K.; Hough, S. E.

    2009-12-01

    Site (material impedance) and topographic (geometric form) effects are known to be key factors that influence seismic ground motions. To characterize site effects, Yong et al. (2009) developed a terrain-based Vs30 prediction model using an automated classification method (Iwahashi and Pike, 2007) that relied on taxonomic criteria (slope gradient, local convexity and surface texture) developed from geomorphometry to identify 16 terrain types from a 1-km spatial resolution (SRTM30 data) digital elevation model of California. On the basis that the underlying framework for this model contains parameters (esp., local convexity) which aptly describe the geometry (i.e., base to height ratio) of relief features that are known to also control the behavior of ground motions (Bouchon, 1973), we extend our investigation to study topographic effects. Focusing on sites that would generally be considered “hard rock,” the classification scheme distinguishes 7 separate terrain types ranging from “moderately eroded mountains” to “well dissected alpine summits.” Observed 1-Hz amplification factors at Southern California Seismographic Network sites reveal a weak but systematic correlation with these 7 terrain types. Significant scatter is also found within each terrain type; typical standard deviations of logarithmic amplification factors are 0.2-0.3. Considering stations that have high amplification factors, we find some that have apparently been misclassified due to data resolution limitations. Many of the remaining stations with higher than expected amplifications are located on or near topographic peaks or ridges. The unusually high amplification factors at hard-rock sites, typically factors of 1.5-2, can most plausibly be explained as a topographic effect.

  4. Effect of wall hardness on hemolysis.

    PubMed

    Yasuda, T; Shimokasa, K; Funakubo, A; Fukui, Y

    2000-08-01

    One of the major problems for artificial organs to develop and to improve is the reduction of hemolysis. The optimum designing of less hemolysis artificial organs is achieved through computational analysis and flow visualization techniques. However, it is impossible to know the quantitative relation between hemolysis and these analytic data. Thus, in vitro studies were performed to estimate these devices on hemolysis because there is no standard for designing these devices with less hemolysis. Therefore, it is essential to reveal the relation between blood flow behaviors and hemolysis. Previous studies reported that hemolysis was caused by a combination of physical factors. In particular, shear stress, pressure, and other fluid dynamical effects were shown to induce hemolysis. In another fluid dynamical experiment reported, the collision flow against the sanded wall was considered the most important factor that directly effected blood damage, which led to hemolysis. The blood flow impact of the collision against the wall effected serious damage to red blood cells. The objective of this study was to point out the relationship between physical force (pressure) in collision flow and hemolysis. In vitro tests using bovine blood and a circulation model that included a jet flow that collides against a wall were conducted. In these tests, we changed the material of the wall by replacing silicone rubber of various thicknesses. The thickness of the silicone rubber is inversely proportional to its hardness. The results show that the increasing rate of hemolysis was lower when the surface was coated by silicone rubber. In conclusion, we considered that it is possible to reduce hemolysis by adjusting the hardness of the material and contacted blood flow.

  5. The hard side of change management.

    PubMed

    Sirkin, Harold L; Keenan, Perry; Jackson, Alan

    2005-10-01

    Everyone agrees that managing change is tough, but few can agree on how to do it. Most experts are obsessed with "soft" issues, such as culture and motivation, but, say the authors, focusing on these issues alone won't bring about change. Companies also need to consider the hard factors-like the time it takes to complete a change initiative, the number of people required to execute it, and so forth. When the authors studied change initiatives at 225 companies, they found a consistent correlation between the outcomes of change programs (success versus failure) and four hard factors, which they called DICE: project duration, particularly the time between project reviews; integrity of performance, or the capabilities of project teams; the level of commitment of senior executives and staff; and the additional effort required of employees directly affected by the change. The DICE framework is a simple formula for calculating how well a company is implementing, or will be able to implement, its change initiatives. The framework comprises a set of simple questions that help executives score their projects on each of the four factors; the lower the score, the more likely the project will succeed. Companies can use DICE assessments to force conversations a bout projects, to gauge whether projects are on track or in trouble, and to manage project portfolios. The authors have used these four factors to predict the outcomes and guide the execution of more than 1,000 change management programs worldwide. Not only has the correlation held, but no other factors (or combination of factors) have predicted outcomes as successfully.

  6. Hard x ray/microwave spectroscopy of solar flares

    NASA Technical Reports Server (NTRS)

    Gary, Dale E.

    1992-01-01

    The joint study of hard x ray and microwave observations of solar flares is extremely important because the two complementary ways of viewing the accelerated electrons yield information that cannot be obtained using hard x rays or microwaves alone. The microwaves can provide spatial information lacking in the hard x rays, and the x ray data can give information on the energy distribution of electrons that remove ambiguities in the radio data. A prerequisite for combining the two data-sets, however, is to first understand which range of microwave frequencies correlate best with the hard x rays. This SMM Guest Investigator grant enabled us to combine multi-frequency OVRO data with calibrated hard x ray data to shed light on the relationship between the two emissions. In particular, the questions of which microwave frequencies correspond to which hard x ray energies, and what is the corresponding energy of the electrons that produce both types of emission are investigated.

  7. Magnetic hysteresis measurements of thin films under isotropic stress.

    NASA Astrophysics Data System (ADS)

    Holland, Patrick; Dubey, Archana; Geerts, Wilhelmus

    2000-10-01

    Nowadays, ferromagnetic thin films are widely applied in devices for information technology (credit cards, video recorder tapes, floppies, hard disks) and sensors (air bags, anti-breaking systems, navigation systems). Thus, with the increase in the use of magnetic media continued investigation of magnetic properties of materials is necessary to help in determining the useful properties of materials for new or improved applications. We are currently interested in studying the effect of applied external stress on Kerr hysteresis curves of thin magnetic films. The Ni and NiFe films were grown using DC magnetron sputtering with Ar as the sputter gas (pAr=4 mTorr; Tsub=55-190 C). Seed and cap layers of Ti were used on all films for adhesion and oxidation protection, respectively. A brass membrane pressure cell was designed to apply in-plane isotropic stress to thin films. In this pressure cell, gas pressure is used to deform a flexible substrate onto which a thin magnetic film has been sputtered. The curvature of the samples could be controlled by changing the gas pressure to the cell. Magneto-Optical in-plane hysteresis curves at different values of strain were measured. The results obtained show that the stress sensitivity is dependent on the film thickness. For the 500nm NiFe films, the coercivity strongly decreased as a function of the applied stress.

  8. Radiation Hard AlGaN Detectors and Imager

    SciTech Connect

    2012-05-01

    Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

  9. Hardness testing of some fissure-sealing materials.

    PubMed

    Ulvestad, H

    1977-11-01

    The mechanical properties of fissure-sealing materials are of significant importance for their durability, i.e. their wear resistance. One of the methods of evaluating a material's resistance to attrition is to apply a hardness test. In the present investigation, the surface hardness of some fissure-sealing materials was tested. Sealants made from diluted composite materials and with inclusion of inorganic filler particles appeared to have a considerable higher surface hardness than the other sealing materials tested.

  10. Fusion of Hard and Soft Information in Nonparametric Density Estimation

    DTIC Science & Technology

    2015-06-10

    Fusion of Hard and Soft Information in Nonparametric Density Estimation∗ Johannes O. Royset Roger J-B Wets Department of Operations Research...univariate density estimation in situations when the sample ( hard information) is supplemented by “soft” information about the random phenomenon. These... hard and soft information, and give rates of convergence. Numerical examples illustrate the value of soft information, the ability to generate a

  11. Effect of Loading Rate Upon Conventional Ceramic Microindentation Hardness

    DTIC Science & Technology

    2002-01-01

    silicate crown glass. In this modification of the tradi- tional Vickers hardness test, both load and displacement were monitored during the indentation...loads up to 30 N. Alumina, two aluminum nitrides, and two zirconias had a dynamic hardness from 9 % to 19 % greater than the static hardness at loads up...M. Hooper, Indentation Creep in Zirconia Ceramics Between 290 K and 1073 K, in Mechanics of Creep, Brittle Materials, A. Cooks and A. Ponter, eds

  12. Shielding a streak camera from hard x rays

    NASA Astrophysics Data System (ADS)

    Schneider, M. B.; Sorce, C.; Loughman, K.; Emig, J.; Bruns, C.; Back, C.; Bell, P. M.; Compton, S.; Hargrove, D.; Holder, J. P.; Landen, O. L.; Perry, T. S.; Shepherd, R.; Young, B. K.

    2004-10-01

    The targets used in the hot halfraum campaign at OMEGA create many hot electrons, which result in a large flux of hard x rays. The hard x rays produce a high background in the streak camera. The background was significantly reduced by wrapping the streak camera with a high-Z material; in this case, 1/8 in. of Pb. The large hard x-ray flux also adds noise to images from framing cameras which use charge-coupled devices.

  13. Powerful jets from black hole X-ray binaries in low/hard X-ray states

    NASA Astrophysics Data System (ADS)

    Fender, R. P.

    2001-03-01

    Four persistent (Cygnus X-1, GX 339-4, GRS 1758-258 and 1E 1740.7-2942) and three transient (GS 2023+38, GRO J0422+32 and GS 1354-64) black hole X-ray binary systems have been extensively observed at radio wavelengths during extended periods in the low/hard X-ray state, which is characterized in X-rays by a hard power-law spectrum and strong variability. All seven systems show a persistent flat or inverted (in the sense that α>~0, where Sν~να) radio spectrum in this state, markedly different from the optically thin radio spectra exhibited by most X-ray transients within days of outburst. Furthermore, in none of the systems is a high-frequency cut-off to this spectral component detected, and there is evidence that it extends to near-infrared or optical regimes. Luminous persistent hard X-ray states in the black hole system GRS 1915+105 produce a comparable spectrum. This spectral component is considered to arise in synchrotron emission from a conical, partially self-absorbed jet, of the same genre as those originally considered for active galactic nuclei. Whatever the physical origin of the low/hard X-ray states, these self-similar outflows are an ever-present feature. The power in the jet component is likely to be a significant (>=5per cent) and approximately fixed fraction of the total accretion luminosity. The correlation between hard X-ray and synchrotron emission in all the sources implies that the jets are intimately related to the Comptonization process, and do not have very large bulk Lorentz factors, unless the hard X-ray emission is also beamed by the same factor.

  14. Floating into Thin Air

    SciTech Connect

    Hazi, A U

    2007-02-06

    On May 18, 2005, a giant helium balloon carrying the High Energy Focusing Telescope (HEFT) sailed into the spring sky over the deserts of New Mexico. The spindly steel and aluminum gondola that houses the optics, detectors, and other components of the telescope floated for 25 hours after its launch from Fort Sumner, New Mexico. For 21 of those hours, the balloon was nearly 40 kilometers above Earth's surface--almost four times higher than the altitude routinely flown by commercial jet aircraft. In the upper reaches of Earth's atmosphere, HEFT searched the universe for x-ray sources from highly energetic objects such as binary stars, galaxy clusters, and supermassive black holes. Before landing in Arizona, the telescope observed and imaged a dozen scientific targets by capturing photons emitted from these objects in the high-energy (hard) x-ray range (above 10 kiloelectronvolts). Among these targets were the Crab synchrotron nebula, the black hole Cygnus X-1 (one of the brightest x-ray sources in the sky), and the blazar 3C454.3. The scientific data gathered from these targets are among the first focused hard x-ray images returned from high altitudes.

  15. Nanomechanical and nanotribological properties of Nb substituted TiN thin films

    SciTech Connect

    Krishna, M. Ghanashyam; Vasu, K.; Padmanabhan, K. A.

    2012-06-25

    Nanomechanical and nanotribological properties of Ti{sub 1-x}Nb{sub x}N (0{<=}x{<=}1) thin films were investigated as a function x. The films were deposited onto polycrystalline nuclear grade 316LN stainless steel (SS) substrate by radio frequency magnetron sputtering in 100% N{sub 2} plasma. The hardness and Young's modulus increased while the friction coefficient and wear volume decreased with increasing Nb substitution. The highest hardness achieved was 31GPa for x=0.77. At the same Nb concentration, the friction coefficient was 0.15 and the elastic recovery was 60%.

  16. Hard and soft acids and bases: structure and process.

    PubMed

    Reed, James L

    2012-07-05

    Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.

  17. Moisture influence on near-infrared prediction of wheat hardness

    NASA Astrophysics Data System (ADS)

    Windham, William R.; Gaines, Charles S.; Leffler, Richard G.

    1991-02-01

    Recently near infrared (NTR) reflectance instrumentation has been used to provide an empirical measure of wheat hardness. This hardness scale is based on the radiation scattering properties of meal particles at 1680 and 2230 nm. Hard wheats have a larger mean particles size (PS) after grinding than soft wheats. However wheat kernel moisture content can influence mean PS after grinding. The objective of this study was to determine the sensitivity of MR wheat hardness measurements to moisture content and to make the hardness score independent of moisture by correcting hardness measurements for the actual moisture content of measured samples. Forty wheat cultivars composed of hard red winter hard red spring soft red winter and soft white winter were used. Wheat kernel subsamples were stored at 20 40 60 and 80 relative humidity (RH). After equilibration samples were ground and the meal analyzed for hardness score (HS) and moisture. HS were 48 50 54 and 65 for 20 40 60 and 80 RH respectively. Differences in HS within each wheat class were the result of a moisture induced change in the PS of the meal. An algorithm was developed to correct HS to 11 moisture. This correction provides HS that are nearly independent of moisture content. 1.

  18. Hardness of covalent and ionic crystals: first-principle calculations.

    PubMed

    Simůnek, Antonín; Vackár, Jirí

    2006-03-03

    A new concept, the strength of bond, and a new form expressing the hardness of covalent and ionic crystals are presented. Hardness is expressed by means of quantities inherently coupled to the atomistic structure of matter, and, therefore, hardness can be determined by first-principles calculations. Good agreement between theory and experiment is observed in the range of 2 orders of magnitude. It is shown that a lower coordination number of atoms results in higher hardness, contrary to common opinion presented in general literature.

  19. Structural precursor to freezing in the hard-disk and hard-sphere systems

    NASA Astrophysics Data System (ADS)

    Truskett, Thomas M.; Torquato, Salvatore; Sastry, Srikanth; Debenedetti, Pablo G.; Stillinger, Frank H.

    1998-09-01

    We show that the simplest model fluids in two and three dimensions, namely, the hard-disk and hard-sphere fluids, exhibit a structural precursor to the freezing transition, which manifests itself as a shoulder in the second peak of the radial distribution function. This feature is not present in the radial distribution function of the low-density fluid. Close examination of the two-dimensional fluid configurations in the vicinity of the freezing transition reveals that the shoulder corresponds to the formation of a distinct structural motif, identifiable as a four-particle hexagonally close-packed arrangement. As the dense fluid approaches the freezing transition, the ordered arrangements form large embryonic domains, commensurate with those seen in the crystal at the melting point. Contrary to the notion that the split second peak is a signature of the amorphous solid, our results support the idea that it is a precursor to the development of long-range order.

  20. Femtosecond laser direct hard mask writing for selective facile micron-scale inverted-pyramid patterning of silicon

    NASA Astrophysics Data System (ADS)

    Kumar, K.; Lee, K. K. C.; Herman, P. R.; Nogami, J.; Kherani, N. P.

    2012-11-01

    We report on the fabrication of high-fidelity inverted-pyramids in crystalline silicon (c-Si) at the 1 μm scale through the selective removal of a silicon nitride (SiNx) hard-mask with a 522 nm femtosecond (fs) laser and subsequent alkaline potassium hydroxide (KOH) etching. Through a series of systematic experiments on a range of hard-mask thicknesses, the use of 20 nm thick SiNx film yielded a 0.6 μm diameter laser-ejected aperture in the hard-mask at a single pulse fluence of 0.45 J cm-2, resulting in 1 μm wide inverted-pyramid structure in c-Si after KOH etching. Anisotropic KOH etching of the partially amorphized c-Si underlying the fs-laser patterned hard mask was found to render clean (111) planes of c-Si. An array of inverted-pyramids on c-Si surfaces as large as 4 cm2 was produced with a defect density of less than 1 in 104. This facile, non-contact, and cleanroom-independent technique serves a variety of applications including anti-reflective texturing of thin c-Si for photovoltaics, wafer marking, labeling, and fabrication of microfluidic and optical devices or laboratories on silicon wafers.

  1. Peroxide interactions with hard tissues: effects on surface hardness and surface/subsurface ultrastructural properties.

    PubMed

    White, Donald J; Kozak, Kathy M; Zoladz, James R; Duschner, Heinz; Götz, Hermann

    2002-01-01

    Laboratory studies were performed to assess the impact of peroxide bleaching on enamel surface and subsurface physical and ultrastructural properties. Human enamel blocks were prepared, polished, and measured for native color. Cyclic bleaching treatments were carried out with soaks in whole stimulated saliva interspersed with bleaching treatments using bulk bleaching gels from commercial bleaching systems including Opalescence (20% and 10% carbamide peroxide systems) and Crest Whitestrips, a hydrogen peroxide gel formula, at doses of 5.3% and 6.5% hydrogen peroxide. Treatments ranged from conditions of normal use (14 hours as recommended for Crest Whitestrips) to excessive bleaching (70 hours). Controls included nontreated as well as treatments with placebo (not containing peroxide) gels. Surface hardness and confocal laser scanning microscopy (CLSM) techniques were used to characterize the effects of bleaching on the physical properties and ultrastructure of the teeth. Tooth color measurements revealed dose-response bleaching in vitro with the increases in L* and decreases in b* normally expected with effective bleaching. Placebo control treatments did not bleach. Surface hardness measurements showed no decreases associated with tooth bleaching. CLSM measurements also showed no effects from tooth bleaches on the surface or subsurface prism architecture of enamel. This was opposed to significant changes seen with even moderate levels of demineralization associated with the caries process. These studies support: (1) the safety of Crest Whitestrips formulas for enamel surfaces and tooth subsurfaces; and (2) the generic safety of peroxide bleaching of hard tissues associated with conditions of both recommended use and overuse.

  2. Thin film hydrogen sensor

    DOEpatents

    Lauf, Robert J.; Hoffheins, Barbara S.; Fleming, Pamela H.

    1994-01-01

    A hydrogen sensor element comprises an essentially inert, electrically-insulating substrate having a thin-film metallization deposited thereon which forms at least two resistors on the substrate. The metallization comprises a layer of Pd or a Pd alloy for sensing hydrogen and an underlying intermediate metal layer for providing enhanced adhesion of the metallization to the substrate. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors, and at least one of the resistors is left uncovered. The difference in electrical resistances of the covered resistor and the uncovered resistor is related to hydrogen concentration in a gas to which the sensor element is exposed.

  3. Method for thinning specimen

    SciTech Connect

    Follstaedt, David M.; Moran, Michael P.

    2005-03-15

    A method for thinning (such as in grinding and polishing) a material surface using an instrument means for moving an article with a discontinuous surface with an abrasive material dispersed between the material surface and the discontinuous surface where the discontinuous surface of the moving article provides an efficient means for maintaining contact of the abrasive with the material surface. When used to dimple specimens for microscopy analysis, a wheel with a surface that has been modified to produce a uniform or random discontinuous surface significantly improves the speed of the dimpling process without loss of quality of finish.

  4. Carbon thin film thermometry

    NASA Technical Reports Server (NTRS)

    Collier, R. S.; Sparks, L. L.; Strobridge, T. R.

    1973-01-01

    The work concerning carbon thin film thermometry is reported. Optimum film deposition parameters were sought on an empirical basis for maximum stability of the films. One hundred films were fabricated for use at the Marshall Space Flight Center; 10 of these films were given a precise quasi-continuous calibration of temperature vs. resistance with 22 intervals between 5 and 80 K using primary platinum and germanium thermometers. Sensitivity curves were established and the remaining 90 films were given a three point calibration and fitted to the established sensitivity curves. Hydrogen gas-liquid discrimination set points are given for each film.

  5. Thin-Film Power Transformers

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.

    1995-01-01

    Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

  6. Deposition of organosilicone thin film from hexamethyldisiloxane (HMDSO) with 50 kHz/33 MHz dual-frequency atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Jiaojiao, LI; Qianghua, YUAN; Xiaowei, CHANG; Yong, WANG; Guiqin, YIN; Chenzhong, DONG

    2017-04-01

    The deposition of organosilicone thin films from hexamethyldisiloxane(HMDSO) by using a dual-frequency (50 kHz/33 MHz) atmospheric-pressure micro-plasma jet with an admixture of a small volume of HMDSO and Ar was investigated. The topography was measured by using scanning electron microscopy. The chemical bond and composition of these films were analyzed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy. The results indicated that the as-deposited film was constituted by silicon, carbon, and oxygen elements, and FTIR suggested the films are organosilicon with the organic component (–CH x ) and hydroxyl functional group(–OH) connected to the Si–O–Si backbone. Thin-film hardness was recorded by an MH–5–VM Digital Micro-Hardness Tester. Radio frequency power had a strong impact on film hardness and the hardness increased with increasing power.

  7. Like Beauty, Complexity is Hard to Define

    NASA Astrophysics Data System (ADS)

    Tsallis, Constantino

    Like beauty, complexity is hard to define and rather easy to identify: nonlinear dynamics, strongly interconnected simple elements, some sort of divisoria aquorum between order and disorder. Before focusing on complexity, let us remember that the theoretical pillars of contemporary physics are mechanics (Newtonian, relativistic, quantum), Maxwell electromagnetism, and (Boltzmann-Gibbs, BG) statistical mechanics - obligatory basic disciplines in any advanced course in physics. The firstprinciple statistical-mechanical approach starts from (microscopic) electro-mechanics and theory of probabilities, and, through a variety of possible mesoscopic descriptions, arrives to (oscopic) thermodynamics. In the middle of this trip, we cross energy and entropy. Energy is related to the possible microscopic configurations of the system, whereas entropy is related to the corresponding probabilities. Therefore, in some sense, entropy represents a concept which, epistemologically speaking, is one step further with regard to energy. The fact that energy is not parameter-independent is very familiar: the kinetic energy of a truck is very different from that of a fly, and the relativistic energy of a fast electron is very different from its classical value, and so on. What about entropy? One hundred and forty years of tradition, and hundreds - we may even say thousands - of impressive theoretical successes of the parameter-free BG entropy have sedimented, in the mind of many scientists, the conviction that it is unique. However, it can be straightforwardly argued that, in general, this is not the case...

  8. Unraveling Quantum Annealers using Classical Hardness

    NASA Astrophysics Data System (ADS)

    Martin-Mayor, Victor; Hen, Itay

    2015-10-01

    Recent advances in quantum technology have led to the development and manufacturing of experimental programmable quantum annealing optimizers that contain hundreds of quantum bits. These optimizers, commonly referred to as ‘D-Wave’ chips, promise to solve practical optimization problems potentially faster than conventional ‘classical’ computers. Attempts to quantify the quantum nature of these chips have been met with both excitement and skepticism but have also brought up numerous fundamental questions pertaining to the distinguishability of experimental quantum annealers from their classical thermal counterparts. Inspired by recent results in spin-glass theory that recognize ‘temperature chaos’ as the underlying mechanism responsible for the computational intractability of hard optimization problems, we devise a general method to quantify the performance of quantum annealers on optimization problems suffering from varying degrees of temperature chaos: A superior performance of quantum annealers over classical algorithms on these may allude to the role that quantum effects play in providing speedup. We utilize our method to experimentally study the D-Wave Two chip on different temperature-chaotic problems and find, surprisingly, that its performance scales unfavorably as compared to several analogous classical algorithms. We detect, quantify and discuss several purely classical effects that possibly mask the quantum behavior of the chip.

  9. Revisiting the phase diagram of hard ellipsoids

    NASA Astrophysics Data System (ADS)

    Odriozola, Gerardo

    2012-04-01

    In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985), 10.1080/00268978500101971] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ≥ 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases.

  10. Unraveling Quantum Annealers using Classical Hardness.

    PubMed

    Martin-Mayor, Victor; Hen, Itay

    2015-10-20

    Recent advances in quantum technology have led to the development and manufacturing of experimental programmable quantum annealing optimizers that contain hundreds of quantum bits. These optimizers, commonly referred to as 'D-Wave' chips, promise to solve practical optimization problems potentially faster than conventional 'classical' computers. Attempts to quantify the quantum nature of these chips have been met with both excitement and skepticism but have also brought up numerous fundamental questions pertaining to the distinguishability of experimental quantum annealers from their classical thermal counterparts. Inspired by recent results in spin-glass theory that recognize 'temperature chaos' as the underlying mechanism responsible for the computational intractability of hard optimization problems, we devise a general method to quantify the performance of quantum annealers on optimization problems suffering from varying degrees of temperature chaos: A superior performance of quantum annealers over classical algorithms on these may allude to the role that quantum effects play in providing speedup. We utilize our method to experimentally study the D-Wave Two chip on different temperature-chaotic problems and find, surprisingly, that its performance scales unfavorably as compared to several analogous classical algorithms. We detect, quantify and discuss several purely classical effects that possibly mask the quantum behavior of the chip.

  11. Magnetic viscosity studies in hard magnetic materials

    SciTech Connect

    Singleton, E.W.; Hadjipanayis, G.C. )

    1990-05-01

    The magnetic viscosity behavior has been studied in several hard magnets with different magnetization reversal mechanisms including barium ferrite powders, Cu-Mn-Al, ferrite magnets, Nd-Fe-B, and SmCo{sub 5}, Sm{sub 2}(Co,Fe,Cu,Zr){sub 17}. The measurements were made with a vibrating sample magnetometer for times up to 60 s and a SQUID magnetometer for longer times in the range of 60--2300 s. For most of the samples the magnetization was found to vary logarithmically with time. The field and temperature dependence of the magnetic viscosity coefficient {ital S} was studied. Here, {ital S} was found to vary with the applied field and it usually peaked around the coercive field {ital H}{sub {ital c}}. The measured values of {ital S}{sub max} at 10 K range from 0.004 to 1.853 emu/g for Cu-Mn-Al and Sm{sub 2}(Co,Fe,Cu,Zr){sub 17}, respectively. The magnetic viscosity coefficient was used together with the magnetic susceptibility to determine the activation volume.

  12. Hard ticks (Acari, Ixodidae) of Croatia

    PubMed Central

    Krčmar, Stjepan

    2012-01-01

    Abstract The present paper is based on original and literature data. In Croatia the first studies on the occurrence of ixodid species were made about 80 years ago. The number of tick species recorded in Croatia considerably increased during the 1950s, 60s, 70s and 80s of the past century. A total of 21 species of hard tick belonging to 5 genera have been recorded in Croatia. Ixodes is the best represented genus, with seven species recorded. Haemaphysalis is represented by six species, followed by Rhipicephalus with four species. Dermacentor and Hyalomma are represented by two species each. The ticks were collected on 47 different host species. Eleven tick species were collected on Bos taurus and Ovis aries, followed by Capra hircus and Equus caballus with 8 species and Canis lupus familiaris with 6 species. On the remaining 42 host species one, two or three tick species were collected. The most widespread tick is Ixodes ricinus which was found on 25 different host species. PMID:23372407

  13. Computational Modeling Develops Ultra-Hard Steel

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Glenn Research Center's Mechanical Components Branch developed a spiral bevel or face gear test rig for testing thermal behavior, surface fatigue, strain, vibration, and noise; a full-scale, 500-horsepower helicopter main-rotor transmission testing stand; a gear rig that allows fundamental studies of the dynamic behavior of gear systems and gear noise; and a high-speed helical gear test for analyzing thermal behavior for rotorcraft. The test rig provides accelerated fatigue life testing for standard spur gears at speeds of up to 10,000 rotations per minute. The test rig enables engineers to investigate the effects of materials, heat treat, shot peen, lubricants, and other factors on the gear's performance. QuesTek Innovations LLC, based in Evanston, Illinois, recently developed a carburized, martensitic gear steel with an ultra-hard case using its computational design methodology, but needed to verify surface fatigue, lifecycle performance, and overall reliability. The Battelle Memorial Institute introduced the company to researchers at Glenn's Mechanical Components Branch and facilitated a partnership allowing researchers at the NASA Center to conduct spur gear fatigue testing for the company. Testing revealed that QuesTek's gear steel outperforms the current state-of-the-art alloys used for aviation gears in contact fatigue by almost 300 percent. With the confidence and credibility provided by the NASA testing, QuesTek is commercializing two new steel alloys. Uses for this new class of steel are limitless in areas that demand exceptional strength for high throughput applications.

  14. Hard X-Ray Footprint Source Sized

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.; Kontar, E. P.

    2010-01-01

    RHESSI has detected compact hard (25 - 100 keV) X-ray sources that are <4 arcseconds (FWHM) in extent for certain flares (Dennis and Pernak (2009). These sources are believed to be at magnetic loop footpoints that are known from observations at other wavelengths to be very small. Flare ribbons seen in the W with TRACE, for example, are approx. 1 arcsecond in width, and white light flares show structure at the approx. 1 arcsecond level. However, Kontar and Jeffrey (2010) have shown that the measured extent should be >6 arcseconds, even if the X-ray emitting thick-target source is point-like. This is because of the strong albedo contribution in the measured energy range for a source located at the expected altitude of 1 Mm near the top of the chromosphere. This discrepancy between observations and model predictions may indicate that the source altitude is significantly lower than assumed or that the RHESSI image reconstruction procedures are not sensitive to the more diffuse albedo patch in the presence of a strong compact source. Results will be presented exploring the latter possibility using the Pixon image reconstruction procedure and other methods based on visibilities.

  15. Revisiting the phase diagram of hard ellipsoids.

    PubMed

    Odriozola, Gerardo

    2012-04-07

    In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985)] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ≥ 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases.

  16. Dynamics of hard sphere colloidal dispersions

    NASA Technical Reports Server (NTRS)

    Zhu, J. X.; Chaikin, Paul M.; Phan, S.-E.; Russel, W. B.

    1994-01-01

    Our objective is to perform on homogeneous, fully equilibrated dispersions the full set of experiments characterizing the transition from fluid to solid and the properties of the crystalline and glassy solid. These include measurements quantifying the nucleation and growth of crystallites, the structure of the initial fluid and the fully crystalline solid, and Brownian motion of particles within the crystal, and the elasticity of the crystal and the glass. Experiments are being built and tested for ideal microgravity environment. Here we describe the ground based effort, which exploits a fluidized bed to create a homogeneous, steady dispersion for the studies. The differences between the microgravity environment and the fluidized bed is gauged by the Peclet number Pe, which measures the rate of convection/sedimentation relative to Brownian motion. We have designed our experiment to accomplish three types of measurements on hard sphere suspensions in a fluidized bed: the static scattering intensity as a function of angle to determine the structure factor, the temporal autocorrelation function at all scattering angles to probe the dynamics, and the amplitude of the response to an oscillatory forcing to deduce the low frequency viscoelasticity. Thus the scattering instrument and the colloidal dispersion were chosen such as that the important features of each physical property lie within the detectable range for each measurement.

  17. Hard Exclusive Meson Production at COMPASS

    NASA Astrophysics Data System (ADS)

    Ter Wolbeek, Johannes

    2016-02-01

    The concept of Generalized Parton Distributions (GPDs) combines two-dimensional spatial information given by form factors, with longitudinal momentum information from Parton Distribution Functions. GPDs provide comprehensive description of the nucleon structure involving a wealth of new information. For instance, according to Ji’s sum rule, the GPDs H and E enable access to the total angular momenta of quarks, antiquarks and gluons. While H can be approached using measurements of electroproduction cross sections, asymmetry measurements in hard exclusive meson production off transversely polarized targets can help to constrain the GPD E and chiral-odd GPDs. In 2007 and 2010 the COMPASS experiment at CERN collected data by scattering a 160GeV/c muon beam off a transversely polarized NH3 target. Exclusive vector-meson production μ + p → μ‧ + p + V with a ρ0 or ω meson in the final state is studied and five single-spin and three double-spin azimuthal asymmetries are measured.

  18. Unraveling Quantum Annealers using Classical Hardness

    PubMed Central

    Martin-Mayor, Victor; Hen, Itay

    2015-01-01

    Recent advances in quantum technology have led to the development and manufacturing of experimental programmable quantum annealing optimizers that contain hundreds of quantum bits. These optimizers, commonly referred to as ‘D-Wave’ chips, promise to solve practical optimization problems potentially faster than conventional ‘classical’ computers. Attempts to quantify the quantum nature of these chips have been met with both excitement and skepticism but have also brought up numerous fundamental questions pertaining to the distinguishability of experimental quantum annealers from their classical thermal counterparts. Inspired by recent results in spin-glass theory that recognize ‘temperature chaos’ as the underlying mechanism responsible for the computational intractability of hard optimization problems, we devise a general method to quantify the performance of quantum annealers on optimization problems suffering from varying degrees of temperature chaos: A superior performance of quantum annealers over classical algorithms on these may allude to the role that quantum effects play in providing speedup. We utilize our method to experimentally study the D-Wave Two chip on different temperature-chaotic problems and find, surprisingly, that its performance scales unfavorably as compared to several analogous classical algorithms. We detect, quantify and discuss several purely classical effects that possibly mask the quantum behavior of the chip. PMID:26483257

  19. Monodisperse hard rods in external potentials.

    PubMed

    Bakhti, Benaoumeur; Karbach, Michael; Maass, Philipp; Müller, Gerhard

    2015-10-01

    We consider linear arrays of cells of volume V(c) populated by monodisperse rods of size σV(c),σ=1,2,..., subject to hardcore exclusion interaction. Each rod experiences a position-dependent external potential. In one application we also examine effects of contact forces between rods. We employ two distinct methods of exact analysis with complementary strengths and different limits of spatial resolution to calculate profiles of pressure and density on mesoscopic and microscopic length scales at thermal equilibrium. One method uses density functionals and the other statistically interacting vacancy particles. The applications worked out include gravity, power-law traps, and hard walls. We identify oscillations in the profiles on a microscopic length scale and show how they are systematically averaged out on a well-defined mesoscopic length scale to establish full consistency between the two approaches. The continuum limit, realized as V(c)→0,σ→∞ at nonzero and finite σV(c), connects our highest-resolution results with known exact results for monodisperse rods in a continuum. We also compare the pressure profiles obtained from density functionals with the average microscopic pressure profiles derived from the pair distribution function.

  20. The thin eggshell problem

    USGS Publications Warehouse

    Stickel, L.F.; Rhodes, L.I.; Gillett, J.W.

    1970-01-01

    It has long been known that DDT and related chemicals can impair the reproduction of birds. In early years of organochlorine pesticide use, widespread mortality occurred immediately following heavy applications of these chemicals, and survivors contained substantial amounts of toxicant in their tissues. Repopulation from untreated areas tended to conceal the extent of the effects. DDT and dieldrin have become ubiquitous and the original source of the chemicals producing bird deaths often cannot be traced. The extent of sublethal effects cannot be fully appraised, although laboratory experiments continually reveal new and potentially deleterious physiological reactions. Thin eggshells have become prevalent among certain declining species of predatory birds. Shell thinning and associated reproductive effects have been produced experimentally in mallard ducks and in sparrow hawks. Coturnix quail fed dietary dosages of p,p'-DDT produced fewer eggs than did untreated birds and the eggs had thinner shells. Hatchability was not significantly altered. Comparisons between these results and those obtained in other studies indicate significant species differences.

  1. Interferometric hard x-ray phase contrast imaging at 204 nm grating period

    SciTech Connect

    Wen Han; Gomella, Andrew A.; Miao, Houxun; Lynch, Susanna K.; Wolfe, Douglas E.; Xiao Xianghui; Liu Chian; Morgan, Nicole

    2013-01-15

    We report on hard x-ray phase contrast imaging experiments using a grating interferometer of approximately 1/10th the grating period achieved in previous studies. We designed the gratings as a staircase array of multilayer stacks which are fabricated in a single thin film deposition process. We performed the experiments at 19 keV x-ray energy and 0.8 {mu}m pixel resolution. The small grating period resulted in clear separation of different diffraction orders and multiple images on the detector. A slitted beam was used to remove overlap of the images from the different diffraction orders. The phase contrast images showed detailed features as small as 10 {mu}m, and demonstrated the feasibility of high resolution x-ray phase contrast imaging with nanometer scale gratings.

  2. Observation of a Soft Tissue by a Zernike Phase Contrast Hard X-ray Microscope

    NASA Astrophysics Data System (ADS)

    Aoki, Sadao; Namikawa, Tadahiro; Hoshino, Masato; Watanabe, Norio

    2007-01-01

    A Zernike-type phase contrast hard X-ray microscope was constructed at the Photon Factory BL3C2 (KEK). A white beam from a bending magnet was monochromatized by a silicon double crystal monochromator. Monochromatic parallel X-ray beam illuminated a sample, and transmitted and diffracted X-ray beams were imaged by a Fresnel zone plate (FZP) which had the outer zone width of 100 nm. A phase plate made of a thin aluminum foil with a pinhole was set at the back focal plane of the FZP. The phase plate modulated the diffraction beam from the FZP, whereas a direct beam passed through the pinhole. The resolution of the microscope was measured by observing a tantalum test pattern at an X-ray energy of 9 keV. A 100nm line-and-space pattern could be resolved. X-ray montage pictures of growing eggs of artemia (plankton) were obtained.

  3. High-density ferroelectric recording using a hard disk drive-type data storage system

    NASA Astrophysics Data System (ADS)

    Aoki, Tomonori; Hiranaga, Yoshiomi; Cho, Yasuo

    2016-05-01

    Ferroelectric probe data storage has been proposed as a novel data storage method in which bits are recorded based on the polarization directions of individual domains. These bits are subsequently read by scanning nonlinear dielectric microscopy. The domain walls of typical ferroelectric materials are quite thin: often only several times the lattice constant, which is advantageous for high-density data storage. In this work, high-density read/write (R/W) demonstrations were conducted using a hard disk drive-type test system, and the writing of bit arrays with a recording density of 3.4 Tbit/in.2 was achieved. Additionally, a series of writing and reading operations was successfully demonstrated at a density of 1 Tbit/in.2. Favorable characteristics of ferroelectric recording media for use with the proposed method are discussed in the latter part of this paper.

  4. Radiation Hardness Tests of SiPMs for the JLab Hall D Barrel Calorimeter

    SciTech Connect

    Yi Qiang, Carl Zorn, Fernando Barbosa, Elton Smith

    2013-01-01

    We report on the measurement of the neutron radiation hardness of silicon photomultipliers (SiPMs) manufactured by Hamamatsu Corporation in Japan and SensL in Ireland. Samples from both companies were irradiated by neutrons created by a 1 GeV electron beam hitting a thin lead target at Jefferson Lab Hall A. More tests regarding the temperature dependence of the neutron radiation damage and self-annealing were performed on Hamamatsu SiPMs using a calibrated Am–Be neutron source from the Jefferson Lab Radiation Control group. As the result of irradiation both dark current and dark rate increase linearly as a function of the 1 MeV equivalent neutron fluence and a temperature dependent self-annealing effect is observed

  5. Friction and wear properties of three hard refractory coatings applied by radiofrequency sputtering

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.

    1977-01-01

    The adherence, friction, and wear properties of thin hard refractory compound coatings applied to 440C bearing steel by radiofrequency sputtering were investigated. Friction and wear tests were done with nonconforming pin on disk specimens. The compounds examined were chromium carbide, molybdenum silicide, and titanium carbide. The adherence, friction, and wear were markedly improved by the application of a bias voltage to the bearing steel substrate during coating deposition. Analysis by X-ray photoelectron spectroscopy indicated that the improvement may be due to a reduction in impurities in bias deposited coatings. A fivefold reduction in oxygen concentration in MoSi2 coating by biasing was noted. Chromium carbide was not effective as an antiwear coating. Molybdenum silicide provided some reduction in both friction and wear. Titanium carbide exhibited excellent friction and antiwear properties at light loads. Plastic flow and transfer of the coating material onto the pin specimen appears to be important in achieving low friction and wear.

  6. Interferometric hard x-ray phase contrast imaging at 204 nm grating period

    NASA Astrophysics Data System (ADS)

    Wen, Han; Wolfe, Douglas E.; Gomella, Andrew A.; Miao, Houxun; Xiao, Xianghui; Liu, Chian; Lynch, Susanna K.; Morgan, Nicole

    2013-01-01

    We report on hard x-ray phase contrast imaging experiments using a grating interferometer of approximately 1/10th the grating period achieved in previous studies. We designed the gratings as a staircase array of multilayer stacks which are fabricated in a single thin film deposition process. We performed the experiments at 19 keV x-ray energy and 0.8 μm pixel resolution. The small grating period resulted in clear separation of different diffraction orders and multiple images on the detector. A slitted beam was used to remove overlap of the images from the different diffraction orders. The phase contrast images showed detailed features as small as 10 μm, and demonstrated the feasibility of high resolution x-ray phase contrast imaging with nanometer scale gratings.

  7. Combined analysis of soft and hard X-ray spectra from flares

    NASA Technical Reports Server (NTRS)

    Gabriel, A. H.; Sherman, J. C.; Bely-Dubau, E.; Orwig, L. E.; Schrijver, J.

    1984-01-01

    An attempt is made to develop a self-consistent model which accounts for the line and continuum data generated by the three X-ray imaging instruments on the SMM satellite. The intensities measured covered the 4-500 kV energy range. The model is based on a differential emission measure and electron beam parameters and is used to predict absolute signals detected by the 15 channels of the SMM sensors. Consideration is given to the thermal contribution, instrumental characteristics, thin target excitation and thick target bremsstrahlung. In comparison with data from a flare event on June 29, 1980, model predictions provide a good fit, including the identification of hard electrons with a 5.3 index during the impulsive phase.

  8. Observation of a Soft Tissue by a Zernike Phase Contrast Hard X-ray Microscope

    SciTech Connect

    Aoki, Sadao; Namikawa, Tadahiro; Hoshino, Masato; Watanabe, Norio

    2007-01-19

    A Zernike-type phase contrast hard X-ray microscope was constructed at the Photon Factory BL3C2 (KEK). A white beam from a bending magnet was monochromatized by a silicon double crystal monochromator. Monochromatic parallel X-ray beam illuminated a sample, and transmitted and diffracted X-ray beams were imaged by a Fresnel zone plate (FZP) which had the outer zone width of 100 nm. A phase plate made of a thin aluminum foil with a pinhole was set at the back focal plane of the FZP. The phase plate modulated the diffraction beam from the FZP, whereas a direct beam passed through the pinhole. The resolution of the microscope was measured by observing a tantalum test pattern at an X-ray energy of 9 keV. A 100nm line-and-space pattern could be resolved. X-ray montage pictures of growing eggs of artemia (plankton) were obtained.

  9. Cytotoxicity of hard and soft denture lining materials.

    PubMed

    Atay, Ayse; Bozok Cetintas, Vildan; Cal, Ebru; Kosova, Buket; Kesercioglu, Atilla; Guneri, Pelin

    2012-01-01

    The cytotoxicity of nine soft and hard lining materials (Mollosil Plus, Ufi Gel SC, Visco-gel, Molloplast-B, GC Tissue Conditioner, Vertex Rapid Simplified, GC Reline Hard, Vertex Self-Curing, Ufi Gel hard C) was evaluated using human gingival fibroblasts (HGFs). Twelve disk samples per lining material were prepared and incubated for 24, 48, 72, and 96 h. Cytotoxicity of each lining material's extract on cultured HGFs was measured using XTT assay. Data were analyzed using one-way ANOVA, post hoc Dunnett's T3 and Bonferroni tests at a significance level of p<0.05. At all incubation periods, all the hard lining materials (Vertex-SC, GC Reline Hard, Vertex-RS, and Ufi Gel hard C) showed cell viability higher than 90%. Among the soft lining materials, although there were no significant differences in cell viability among the different incubation periods for each lining material (p>0.05), autopolymerized acrylic-based GC Tissue Conditioner showed significantly lower cell viability than the other soft lining materials at each incubation period. Among the hard lining materials, there were no significant differences both among the materials and across all incubation periods for each lining material (p>0.05). In conclusion, all soft and hard liners exhibited good biocompatibility regardless of incubation time, except for GC Tissue Conditioner.

  10. Educating Hard of Hearing Children. Special Education in Transition 2.

    ERIC Educational Resources Information Center

    Ross, Mark, Ed.; Nober, Linda W., Ed.

    Viewpoints of an audiologist, speech-language pathologist, special educator, classroom teacher, and parent are presented in the book on the implications of P.L. 94-142, the Education for All Handicapped Children Act, for hard of hearing students. In the introduction, M. Ross considers the status of many hard of hearing students, noting the…

  11. Wheat Quality Council, Hard Spring Wheat Technical Committee, 2014 Crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eleven experimental lines of hard spring wheat were grown at up to five locations in 2014 and evaluated for kernel, milling, and bread baking quality against the check variety Glenn. Wheat samples were submitted through the Wheat Quality Council and processed and milled at the USDA-ARS Hard Red Spr...

  12. Statistical Study of Hard X-ray Footpoint Region

    NASA Astrophysics Data System (ADS)

    Sato, J.

    2003-12-01

    We show statistical characteristics of hard X-ray footpoint sources derived from THE YOHKOH FLARE IMAGE CATALOGUE. We use many hard X-ray images over the whole YOHKOH mission period (1991/08 - 2001/12) and the study is concentrated on following two points. 1) Average height of hard X-ray footpoint sources in the four HXT(Hard X-ray Telescope) energy bands (14-23, 23-33, 33-53, 53-93 keV). 2) Spectral characteristics of hard X-ray footpoint sources. We mainly revealed that A) the hard X-ray emission comes from just above the Hα emitting region and the accelerated electrons loose their energy within 1000 km length leading to the high density around footpoints, and that B) Many hard X-ray footpoint sources show a broken power-law spectrum with very hard spectrum in the low energy range (20-30 keV), suggesting a cut off energy of accelerated electrons is around 20 keV - 30 keV at least.

  13. Hardness Analysis. Training Module 5.215.2.77.

    ERIC Educational Resources Information Center

    Bonte, John L.; Davidson, Arnold C.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with hardness analysis using the EDTA method and the calculation of hardness given metal ion concentrations and a factor table. Included are objectives, an instructor guide, student handouts, and transparency masters. A video tape is also…

  14. Dough Rheology and Wet Milling of Hard Waxy Wheat Flours

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To realize the full potential of waxy wheat (Triticum aestivum L.), wet milling of waxy wheat flour to produce gluten and waxy wheat starch was investigated. Flours of six advanced lines of waxy hard wheats, one normal hard wheat (‘Karl 92’), and one partial waxy wheat (‘Trego’) were fractionated by...

  15. Critical Configurations of Hard Disks on the Torus

    SciTech Connect

    Mason, J.

    2013-04-16

    CCHDT constructs and classifies various arrangements of hard disks of a single radius places on the unit square with periodic boundary conditions. Specifially, a given configuration is evolved to the nearest critical point on a smoothed hard disk energy fuction, and is classified by the adjacency matrix of the canonically labelled contact graph.

  16. Employing the Hard-Core: Internal Organizational Effects.

    ERIC Educational Resources Information Center

    Champagne, J. E.; And Others

    This paper is presented with the hope that those studying or directly involved in the utilization of hard-core persons in employment may gain insights which may make their tasks easier and more productive. It is written in a readable and non-technical nature and integrates experiences of hard-core utilization with accepted organization theory.…

  17. Wear resistance of TiAlSiN thin coatings.

    PubMed

    Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

    2012-12-01

    In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions.

  18. Combinatorial investigation of Fe-B thin-film nanocomposites.

    PubMed

    Brunken, Hayo; Grochla, Dario; Savan, Alan; Kieschnick, Michael; Meijer, Jan D; Ludwig, Alfred

    2011-10-01

    Combinatorial magnetron sputter deposition from elemental targets was used to create Fe-B composition spread type thin film materials libraries on thermally oxidized 4-in. Si wafers. The materials libraries consisting of wedge-type multilayer thin films were annealed at 500 or 700 °C to transform the multilayers into multiphase alloys. The libraries were characterized by nuclear reaction analysis, Rutherford backscattering, nanoindentation, vibrating sample magnetometry, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Young's modulus and hardness values were related to the annealing parameters, structure and composition of the films. The magnetic properties of the films were improved by annealing in a H2 atmosphere, showing a more than tenfold decrease in the coercive field values in comparison to those of the vacuum-annealed films. The hardness values increased from 8 to 18 GPa when the annealing temperature was increased from 500 to 700 °C. The appearance of Fe2B phases, as revealed by XRD and TEM, had a significant effect on the mechanical properties of the films.

  19. Combinatorial investigation of Fe–B thin-film nanocomposites

    PubMed Central

    Brunken, Hayo; Grochla, Dario; Savan, Alan; Kieschnick, Michael; Meijer, Jan D; Ludwig, Alfred

    2011-01-01

    Combinatorial magnetron sputter deposition from elemental targets was used to create Fe–B composition spread type thin film materials libraries on thermally oxidized 4-in. Si wafers. The materials libraries consisting of wedge-type multilayer thin films were annealed at 500 or 700 °C to transform the multilayers into multiphase alloys. The libraries were characterized by nuclear reaction analysis, Rutherford backscattering, nanoindentation, vibrating sample magnetometry, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Young's modulus and hardness values were related to the annealing parameters, structure and composition of the films. The magnetic properties of the films were improved by annealing in a H2 atmosphere, showing a more than tenfold decrease in the coercive field values in comparison to those of the vacuum-annealed films. The hardness values increased from 8 to 18 GPa when the annealing temperature was increased from 500 to 700 °C. The appearance of Fe2B phases, as revealed by XRD and TEM, had a significant effect on the mechanical properties of the films. PMID:27877435

  20. Antiferromagnetic domains in epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Scholl, Andreas

    2002-03-01

    Interface and surface effects play a central role in modern magnet structures. Magnetic exchange coupling and bias, spin injection across the boundary between magnetic and non-magnetic layers, and the surface and interface anisotropy in multilayers are examples for interface phenomena that are utilized in magneto-electronics. In particular, the microscopic origin of exchange bias at ferromagnet/antiferromagnet interfaces is still an unsolved problem despite of intense research, driven by the important application of exchange bias in hard disk read-heads and magnetic RAM. Knowledge of the microscopic magnetic structure in antiferromagnetic thin films and surfaces is of crucial importance for a better understanding of the exchange bias effect. Microscopic experiments on magnetically coupled ferromagnet/antiferromagnet layers using X-ray Photoemission Electron Microscopy (X-PEEM) now provide a new insight into the microscopic processes at this important interface. Using a combination of x-ray magnetic dichroism (XMD) contrast and microscopic electron yield detection we have resolved the magnetic domain structure in LaFeO3 and NiO thin films and crystals. The antiferromagnetic domain structure is linked to the crystallographic structure of the material and vanishes approaching the magnetic ordering temperature. Ferromagnetic films grown on the antiferromagnetic substrate show a corresponding ferromagnetic domain structure, an uniaxial exchange anistropy and a local bias which increases with decreasing domain size, suggesting a statistical origin of the bias effect. The role of uncompensated interface spins will also be discussed. We will present first experiments on magnetic interlayer coupling across metallic antiferromagnets, which suggest a similar origin of bias in full-metallic exchange bias system. A. Scholl et al., Science 287, 1014 (2000), F. Nolting et al., Nature 405, 767 (2000), H. Ohldag et al., Phys. Rev. Lett. 86, 2878 (2001)

  1. Interaction of Nano-Sized Materials With Polymer Chains in Polymer-Nanocomposite Thin Films-An AFM Perspective

    NASA Astrophysics Data System (ADS)

    Verma, Gaurav; Kaushik, Anupama; Ghosh, Anup K.

    2011-12-01

    Nanocomposite thin films were prepared with polyurethane as a matrix and organically modified clay as a filler. The interfacial interaction between the exfoliated clay nanoplatelets and the polymeric chains has been investigated by using Atomic Force Microscopy (AFM). The nanoclay platelets show a preferential association with the hard domains of polyurethane matrix on the surface of the thin films. The pendant hydroxyl group on the nanoplatelets attract the isocyanate of the polyisocyanate and a urethane group is formed. This leads to the `clouding' and `entwining' of the nanoplatelets by the hard segmental chains. This is the first visual evidence of nanomaterial filler and polymer matrix interaction and it could open up a spectrum of novel property achievements in nanocomposite thin films. Also the understanding of this interaction can lead to more controlled architecture of nanocomposites.

  2. Effects of adhesion on the measurement of thin film mechanical properties by nanoindentation

    SciTech Connect

    Tsui, T.Y.; Ross, C.A.; Pharr, G.M.

    1997-06-01

    Experiments have been performed on soft aluminum films deposited on hard ceramic substrates to explore the influences of interfacial adhesion on mechanical property measurement by nanoindentation. The substrate materials included soda-lime silicate glass, aluminum oxynitride (ALON), and (100) sapphire. Thin films of high purity aluminum were sputtered onto each substrate to a thickness of 500 nm. Because the films were deposited simultaneously, the only major difference in the specimens was the nature of the substrate, which exerts an important influence on film adhesion through interfacial chemistry. Of the substrates examined, aluminum adheres strongly to glass and sapphire, but poorly to ALON. In addition, two different types of aluminum films on sapphire were examined - one with and the other without a 10 nm interlayer of amorphous carbon which significantly reduces film adhesion. Testing revealed important differences in the hardness of the specimens when measured by standard nanoindentation methods. Characterization of the residual hardness impressions by high resolution scanning electron microscopy showed that the hardness differences arise from an influence of interfacial debonding and film delamination on pile-up in the film. Furthermore, when the pile-up is accounted for in contact area determinations, the film hardness is actually independent of the substrate, thus indicating that the hardness differences observed in nanoindentation testing are an artifact of the testing analysis procedure. Results of the experiments are documented and discussed. 8 refs., 6 figs., 1 tab.

  3. Surface Integrity of Hard Metal Parts Machined by WEDM

    NASA Astrophysics Data System (ADS)

    Plaza, S.; Izquierdo, B.; Sanchez, J. A.; Ortega, N.; Ramos, J. M.

    2009-11-01

    Hard metal is characterised by having a extremely high hardness and high wear resistance, and those characteristics make difficult conventional machining. Electrical Discharge Machining (EDM) has become an attractive and feasible method for the manufacturing of precision hard metal tooling, and it is now an alternative to classical diamond grinding. This is due to the thermal nature of material removal mechanism in EDM, which is therefore independent on part hardness. This work pays attention to the analysis of surface integrity in wire EDM'ed hard metal parts. Damages on the machined surfaces have been characterised for different cutting regimes. Special attention has been paid to the heat affected zone, since it is in this zone where cracking mostly occurs. The study includes the analysis of the chemical composition of the affected layers. Additionally, the influence of successive trim cuts on surface roughness is addressed.

  4. Hardness and shock absorption of silicone rubber for mouth guards.

    PubMed

    Auroy, P; Duchatelard, P; Zmantar, N E; Hennequin, M

    1996-04-01

    Silicone rubbers have general properties that make them suitable for the fabrication of custom-made mouth guards. This study evaluated the shock absorption properties and Shore A hardness of several silicone rubbers and derived products, compared their values with those of materials commonly used for the manufacture of mouth guards, and correlated the shock absorption and transmission abilities of these different materials with their Shore hardness. Silicone rubbers absorb shock better than the materials currently used for custom-made mouth guards. In addition, to adapt mouth guards to particular sports, the properties of the silicone rubbers can be appropriately modified by the addition of oils or glass fiber reinforcement. Statistical analysis of hardness values and transmitted forces for the 27 materials tested indicates that the maximum transmitted force increases with hardness. However, this relationship is not linear, and departure from linearity is greatest for minimal and maximal hardness values.

  5. Nanoporous hard carbon membranes for medical applications.

    PubMed

    Narayan, Roger J; Jin, Chunming; Menegazzo, Nicola; Mizaikoff, Boris; Gerhardt, Rosario A; Andara, Melanie; Agarwal, Arvind; Shih, Chun-Che; Shih, Chun-Ming; Lin, Shing-Jong; Su, Yea-Yang

    2007-01-01

    Current blood glucose sensors have proven to be inadequate for long term in vivo applications; membrane biofouling and inflammation play significant roles in sensor instability. An ideal biosensor membrane material must prevent protein adsorption and promote integration of the sensor with the surrounding tissue. Furthermore, biosensor membranes must be sufficiently thin and porous in order to allow the sensor to rapidly respond to fluctuations in analyte concentration. In this study, the use of diamondlike carbon-coated anodized aluminum oxide as a potential biosensor membrane is discussed. Diamondlike carbon films and diamondlike carbon-coated anodized aluminum oxide nanoporous membranes were examined using scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and platelet rich plasma testing. The diamondlike carbon-coated anodized aluminum oxide membranes remained free from protein adsorption during in vitro platelet rich plasma testing. We anticipate that this novel membrane could find use in immunoisolation devices, pacemakers, kidney dialysis membranes, microdialysis systems, and other devices facing biocompatibility issues that limit in vivo function.

  6. Reliability of hard plastic clad silica fibers

    NASA Astrophysics Data System (ADS)

    Skutnik, Bolesh J.; Spaniol, Stefan

    2006-04-01

    New formulations of cladding materials have become available in recent times for Hard Plastic Clad Silica (HPCS) fibers, Initial data showed gains in some properties, particularly dynamic strength, especially for high numerical aperture (NA) fibers. A systematic study has been undertaken to determine the full strength and fatigue behavior of these HPCS fibers and to make comparisons to earlier HPCS fibers. Preliminary results, now confirmed, has shown improved median dynamic strength and higher Weibull slope. Full results are presented below including fatigue behavior and optical properties. These fibers have many applications and benefits in the high power delivery and medical laser uses as highlighted below. High power diode laser systems with their laser diode bars and arrays not only require special fibers to couple directly to the diode emitters, but also require special fibers to couple from the laser to application sites. These latter power delivery fibers are much larger than the internal fibers but still must be flexible, and have not only good strength but also good fatigue behavior. This particularly important industrial systems using robotic arms to apply the high power laser energy at a treatment site. The optical properties of HPCS fibers are well suited for the needs of the delivery of high power from diode laser bars and arrays to an application site. Benefits of strong median dynamic strengths and tighter flaw distributions in such cases will be discussed. Many medical applications, especially endoscopic ones, can benefit from the use of highly flexible, high NA, cost effective, HPCS optical fibers. Benefits of high strength and good fatigue behavior for such fibers in endoscopic procedures, including laser surgery, are discussed briefly including implications for mechanical reliability in medical and industrial settings.

  7. Converting hard copy documents for electronic dissemination

    SciTech Connect

    Hoffman, F.

    1994-12-31

    Since the advent of computer systems, the goal of a paperless office, and even a paperless society, has been pursued. While the normal paper flow in an organization is far from totally automated, particularly for items requiring signatures or authorizations, electronic information dissemination is becoming an almost simple task. The reasons for providing on-line documents are many and include faster and easier access for everyone, elimination of printing costs, reduction of wasted shelf and desk space, and the security of having a centrally-located, always up-to-date document. New computer software even provides the user with the ability to annotate documents and to have bookmarks so that the old scribbled-in and dog-eared manual can be replaced without loosing this `customizability`. Moreover, new hypermedia capabilities mean that documents can be read in a non-linear fashion and can include color figures and photographs, audio, and even animation sequences, capabilities which exceed those of paper. The proliferation of network-based information servers, coupled with the growth of the Internet, has enticed academic, governmental, and even commercial organizations to provide increasing numbers of documents and data bases in electronic form via the network, not just to internal staff, but to the public as well. Much of this information, which includes everything from mundane company procedures to spiffy marketing brochures, was previously published only in hard copy. Converting existing documents to electronic form and producing only electronic versions of new documents poses some interesting challenges to the maintainer or author.

  8. Thin film ion conducting coating

    DOEpatents

    Goldner, Ronald B.; Haas, Terry; Wong, Kwok-Keung; Seward, George

    1989-01-01

    Durable thin film ion conducting coatings are formed on a transparent glass substrate by the controlled deposition of the mixed oxides of lithium:tantalum or lithium:niobium. The coatings provide durable ion transport sources for thin film solid state storage batteries and electrochromic energy conservation devices.

  9. Dewetting of Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Dixit, P. S.; Sorensen, J. L.; Kent, M.; Jeon, H. S.

    2001-03-01

    DEWETTING OF THIN POLYMER FILMS P. S. Dixit,(1) J. L. Sorensen,(2) M. Kent,(2) H. S. Jeon*(1) (1) Department of Petroleum and Chemical Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, jeon@nmt.edu (2) Department 1832, Sandia National Laboratories, Albuquerque, NM. Dewetting of thin polymer films is of technological importance for a variety of applications such as protective coatings, dielectric layers, and adhesives. Stable and smooth films are required for the above applications. Above the glass transition temperature (Tg) the instability of polymer thin films on a nonwettable substrate can be occurred. The dewetting mechanism and structure of polypropylene (Tg = -20 ^circC) and polystyrene (Tg = 100 ^circC) thin films is investigated as a function of film thickness (25 Åh < 250 Åand quenching temperature. Contact angle measurements are used in conjunction with optical microscope to check the surface homogeneity of the films. Uniform thin films are prepared by spin casting the polymer solutions onto silicon substrates with different contact angles. We found that the stable and unstable regions of the thin films as a function of the film thickness and quenching temperature, and then constructed a stability diagram for the dewetting of thin polymer films. We also found that the dewetting patterns of the thin films are affected substantially by the changes of film thickness and quenching temperature.

  10. Methods of Producing Thin Films,

    DTIC Science & Technology

    The report describes various methods of producing thin films , especially for microelectronics. In addition to the classical methods of forming thin ... films by vacuum vapor deposition, it also describes processes of diode sputtering and modern methods of cathode sputtering by means of a third

  11. Thin film atomic hydrogen detectors

    NASA Technical Reports Server (NTRS)

    Gruber, C. L.

    1977-01-01

    Thin film and bead thermistor atomic surface recombination hydrogen detectors were investigated both experimentally and theoretically. Devices were constructed on a thin Mylar film substrate. Using suitable Wheatstone bridge techniques sensitivities of 80 microvolts/2x10 to the 13th power atoms/sec are attainable with response time constants on the order of 5 seconds.

  12. Magnetochromatic thin-film microplates.

    PubMed

    He, Le; Janner, Michael; Lu, Qipeng; Wang, Mingsheng; Ma, Hua; Yin, Yadong

    2015-01-07

    A new type of magnetochromatic material is developed based on thin-film interference of microplates self-assembled from super-paramagnetic nanocrystals. Dynamic optical tuning can be achieved through orientational manipulation of free-standing super-paramagnetic thin-film microplates using external magnetic fields.

  13. Thin Film Inorganic Electrochemical Systems.

    DTIC Science & Technology

    1995-07-01

    determined that thin film cathodes of LiCoO2 can be readily performed by either spray pyrolysis or spin coating . These cathodes are electrochemically...active. We have also determined that thin film anodes of Li4Ti5O12 can be prepared by spray pyrolysis or spin coating . These anodes are also

  14. Multilayer Thin-Film Microcapacitors

    NASA Technical Reports Server (NTRS)

    Thakoor, Sarita; Thakoor, Anil; Karmon, Dan

    1995-01-01

    Miniature capacitors containing multiple alternating thin-film dielectric and metal layers proposed, especially for use in integrated and hybrid electronic circuits. Because capacitance inversely proportional to thickness of dielectric layers, use of thin, high-quality dielectric layers affords capacitance and energy-storage densities much greater than now available. These devices much smaller and more reliable than state-of-art capacitors.

  15. Starch granule size distribution of hard red winter and hard red spring wheat: Its effects on mixing and breadmaking quality.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch was isolated from 98 hard red winter (HRW) wheat and 99 hard red spring (HRS) wheat. Granule size/volume distributions of the isolated starches were analyzed using a laser diffraction particle size analyzer. There were significant differences in the size distribution between HRW and HRS whe...

  16. Anti-Reflective and Waterproof Hard Coating for High Power Laser Optical Elements

    NASA Astrophysics Data System (ADS)

    Murahara, Masataka; Yabe, Takashi; Uchida, Shigeaki; Yoshida, Kunio; Okamoto, Yoshiaki

    2006-05-01

    A hard coating method of single crystalline porous silica film is widely used for high power laser optical elements in the air. However, there is no protective hard coating method for the elements to survive high power laser irradiance while in the water. We, thus, developed a new method for a waterproof coating with photo-oxidation of silicone oil. The silicone oil was spin-coated onto the surface of optical elements, and then irradiated with a xenon excimer lamp in the air. In this treatment, a protective coating for plastic lenses, mirrors, and nonlinear optical crystals, which are highly deliquescent, was developed by taking advantage of the phenomenon in which organic silicone oil is transformed to inorganic amorphous glass by a process of photo-oxidation. This technique has enabled an optical thin coating film to transmit ultraviolet rays of wavelengths under 200 nm and possess the characteristics of homogeneity, high density, resistance to environment, anti-reflectiveness, resistance to water, and Mohs' scale of 5, which is comparable to apatite. This allows us to cool a slab laser head and use as a mirror for underwater laser welding.

  17. Imaging of cochlear tissue with a grating interferometer and hard X-rays

    SciTech Connect

    Richter, Claus-Peter; Shintani-Smith, Stephanie; Fishman, Andrew; David, Christian; Robinson, Ian; Rau, Christoph

    2010-01-28

    This article addresses an important current development in medical and biological imaging: the possibility of imaging soft tissue at resolutions in the micron range using hard X-rays. Challenging environments, including the cochlea, require the imaging of soft tissue structure surrounded by bone. We demonstrate that cochlear soft tissue structures can be imaged with hard X-ray phase contrast. Furthermore, we show that only a thin slice of the tissue is required to introduce a large phase shift. It is likely that the phase contrast image of the soft tissue structures is sufficient to image the structures even if surrounded by bone. For the present set of experiments, structures with low-absorption contrast have been visualized using in-line phase contrast imaging and a grating interferometer. The experiments have been performed at the Advanced Photon Source at Argonne National Laboratories, a third generation source of synchrotron radiation. The source provides highly coherent X-ray radiation with high-photon flux (>10{sup 12} photons/s) at high-photon energies (5-70 keV). Radiographic and light microscopy images of the gerbil cochlear slice samples were compared. It has been determined that a 20-{micro}m thick tissue slice induces a phase shift between 1/3{pi} and 2/3{pi}.

  18. Colored hard coatings with AlN–TiN multilayer structures

    SciTech Connect

    Hong Lu, Jong Ying Chen, Bo

    2014-03-15

    AlN–TiN multilayer structures can be used to extend the color gamut of hard coatings while maintaining good hardness and corrosion resistance. This study used reactive magnetron sputtering on a glass substrate to produce coatings with a microhardness of 19 GPa as well as optical reflectance exceeding 80% and controllable saturation (chroma) for various hues of red, yellow, green, blue, and purple. The authors characterized the complex index of refraction of the TiN films using ellipsometry; the real refractive indices of the AlN films were derived from the reflectance values obtained using photometry. Finally, the colors of the samples were quantified using CIE-1931 chromaticity coordinates in the L*a*b* color space, and the microhardness of the films was measured using a nanoindenter. Simulation results using a multiple-beam-interference recursive method presented good consistency with experimental measurements with regard to the optical reflective spectra of AlN–TiN multilayer thin film samples.

  19. Thin EFG octagons

    NASA Astrophysics Data System (ADS)

    Kalejs, J. P.

    1994-03-01

    This report describes work to advance the manufacturing line capabilities in crystal growth and laser cutting of Mobil Solar's unique edge-defined film-fed growth (EFG) octagon technology and to reduce the manufacturing costs of 10 cm x 10 cm polycrystalline silicon EFG wafers. The report summarizes the significant technical improvements in EFG technology achieved in the first 6 months of the PVMaT Phase 2 and the success in meeting program milestones. Technical results are reported for each of the three main pregrain areas: Task 5 -- Thin octagon growth (crystal growth) to reduce the thickness of the octagon to 200 microns; Task 6 -- Laser cutting-to improve the laser cutting process so as to produce wafers with decreased laser cutting damage at increased wafer throughput rates; and Task 7 -- Process control and product specification to implement advanced strategies in crystal growth process control and productivity designed to increase wafer yields.

  20. Ferromagnetic thin films

    DOEpatents

    Krishnan, K.M.

    1994-12-20

    A ferromagnetic [delta]-Mn[sub 1[minus]x]Ga[sub x] thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4[+-]0.05. 7 figures.

  1. Thin film hydrogen sensor

    DOEpatents

    Lauf, R.J.; Hoffheins, B.S.; Fleming, P.H.

    1994-11-22

    A hydrogen sensor element comprises an essentially inert, electrically-insulating substrate having a thin-film metallization deposited thereon which forms at least two resistors on the substrate. The metallization comprises a layer of Pd or a Pd alloy for sensing hydrogen and an underlying intermediate metal layer for providing enhanced adhesion of the metallization to the substrate. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors, and at least one of the resistors is left uncovered. The difference in electrical resistances of the covered resistor and the uncovered resistor is related to hydrogen concentration in a gas to which the sensor element is exposed. 6 figs.

  2. Ferromagnetic thin films

    DOEpatents

    Krishnan, Kannan M.

    1994-01-01

    A ferromagnetic .delta.-Mn.sub.1-x Ga.sub.x thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of .delta.-Mn.sub.1-x Ga.sub.x overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of .delta.-Mn.sub.1-x Ga.sub.x and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4 .+-.0.05.

  3. Selective inorganic thin films

    SciTech Connect

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T.

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  4. Thin wire pointing method

    NASA Technical Reports Server (NTRS)

    Green, G.; Mattauch, R. J. (Inventor)

    1983-01-01

    A method is described for forming sharp tips on thin wires, in particular phosphor bronze wires of diameters such as one-thousandth inch used to contact micron size Schottky barrier diodes, which enables close control of tip shape and which avoids the use of highly toxic solutions. The method includes dipping an end of a phosphor bronze wire into a dilute solution of sulfamic acid and applying a current through the wire to electrochemically etch it. The humidity in the room is controlled to a level of less than 50%, and the voltage applied between the wire and another electrode in the solutions is a half wave rectified voltage. The current through the wire is monitored, and the process is stopped when the current falls to a predetermined low level.

  5. Polyimide Aerogel Thin Films

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  6. Holographic thin film analyzer

    NASA Technical Reports Server (NTRS)

    Williams, J. R.; Norden, B. N. (Inventor)

    1973-01-01

    A system for the analysis and measurement of thin films in which the light output of a laser is split into two beams is discribed. The first beam is focused to illuminate the entire area of a photographic plate and the second beam is colummated and directed through a relatively small portion of the photographic plate onto the sample with the film to be observed. The surface of the sample is positioned at a slight angle with respect to a plane normal to the second beam and the light reflected from the sample arrives back at the photographic plate in a region other than through which the second beam originally passes. By making two successive exposures during the deposition of material on the surface of the sample, holograms are recorded on the photographic plate. The plate is then developed and interference lines of the hologram provide a measurement of the film or material deposited between exposure.

  7. Thin θ -film optics

    NASA Astrophysics Data System (ADS)

    Huerta, Luis

    2016-12-01

    A Chern-Simons theory in 3D is accomplished by the so-called θ term in the action (θ /2 )∫F ∧F , which contributes only to observable effects on the boundaries of such a system. When electromagnetic radiation interacts with the system, the wave is reflected and its polarization is rotated at the interface, even when both the θ system and the environment are pure vacuum. These topics have been studied extensively. Here, we investigate the optical properties of a thin θ film, where multiple internal reflections could interfere coherently. The cases of pure vacuum and a material with magnetoelectric properties are analyzed. It is found that the film reflectance is enhanced compared to ordinary non-θ systems and the interplay between magnetoelectric properties and the θ parameter yield film opacity and polarization properties which could be interesting in the case of topological insulators, among other topological systems.

  8. Hard x-ray photoelectron spectroscopy and x-ray standing waves

    NASA Astrophysics Data System (ADS)

    Lee, Tien-Lin

    2006-03-01

    Using the brilliant undulator radiation available from the third generation synchrotron sources, hard x-ray photoelectron spectroscopy (HAXPES) has become an emerging field in the recent years. With the excitation energy used in HAXPES one can benefits from the large mean free path of fast electrons (˜ 5 nm for electrons of 6 keV kinetic energy) in probing the bulk electronic properties of materials. For high-resolution studies, photon energy bandwidth narrower than 100 meV is also readily achievable in the hard x-ray range with crystal monochromators. In addition, working with hard x-ray offers the possibility for combining photoelectron spectroscopy with x-ray standing wave (XSW) method. With the high spatial resolution from XSWs, this unique combination can provide site-specific, chemical and electronic information for studying surfaces, buried interfaces, thin films and bulk crystals. In this talk, I will briefly mention some HAXPES experiments detecting electrons up to 14.5 keV [1,2]. I will then sketch the principle of combining XSWs with HAXPES and present results from some recent applications using this combination: (1) chemical state-specific surface structure determination with core-level photoemission, (2) site-specific valence x-ray photoelectron spectroscopy and (3) XSW imaging with core-level photoemission. [1] S. Thiess, C. Kunz, B.C.C. Cowie, T.-L. Lee, M. Renier, and J. Zegenhagen. Solid State Communications 132, 589 (2004) [2] C. Kunz, S. Thiess, B.C.C. Cowie, T.-L. Lee, and J. Zegenhagen, Nuclear Instruments and Methods A 547, 73 (2005).

  9. Environmentally benign hardness removal using ion-exchange fibers and snowmelt.

    PubMed

    Greenleaf, John E; Sengupta, Arup K

    2006-01-01

    Many industrial unit operations and unit processes require near-complete removal of hardness to avoid scaling in heat-transfer equipment, fouling in membranes, and high consumption of detergents and sequestering chemicals in cooling and wash water. Lime softening and cation exchange are the most commonly used processes practiced to date for hardness removal. Herein, we report and discuss the results and attributes of a new hardness removal process using ion-exchange fibers (IX-fibers). Most importantly, the process uses harvested snowmelt (or rainwater) as the regenerant chemical along with sparged carbon dioxide. Consequently, the spent regenerant does not contain a high concentration of aggressive chemicals such as sodium chloride or acid like traditional ion-exchange processes nor does the process produce voluminous sludges similar to lime softening. The bulk of carbon dioxide consumed during regeneration remains sequestered in the aqueous phase as alkalinity. IX-fibers form the heart of the process. They are essentially thin cylindrical polymeric strands 10-20 microm in diameter. The weak-acid carboxylate functional groups reside near to the surface of these cylindrical fibers. Low intraparticle diffusional resistance is the underlying reason IX-fibers are amenable to efficient regeneration with snowmelt sparged with carbon dioxide. When the carbon dioxide partial pressure is increased to 6.8 atm, over 90% calcium desorption efficiency is obtained. On the contrary, commercial weak-acid ion-exchange resins in spherical bead forms are ineffective for regeneration with carbon-dioxide-sparged snowmelt due to extremely slow ion-exchange kinetics involving counter-transport of Ca2+ and H+.

  10. Development of High Resolution Hard X-Ray Telescope with Multi-Layer Coatings

    NASA Technical Reports Server (NTRS)

    Gorenstein, Paul; Brinton, John C. (Technical Monitor)

    2005-01-01

    This is the annual report for the third year of a three-year program. Previous annual reports have described progress achieved in the first and second years. The major objective of this program is the development of a focusing hard X-ray telescope with moderately high angular resolution, i.e. comparable to the telescopes of XMM-Newton. The key ingredients of the telescope are a depth graded multilayer coatings and electroformed nickel substrates that are considerably lighter weight than those of previous missions such as XMM-Newton, which have had conventional single metal layer reflective coatings and have operated at much lower energy X-rays. The ultimate target mission for this technology is the Hard X-Ray Telescope (HXT) of the Constellation X-Ray Mission. However, it is applicable to potential SMEX and MIDEX programs as well. We are building upon technology that has proven to be successful in the XMM-Newton and SWIFT missions. The improvements that we are adding are a significant reduction in mass without much loss of angular resolution and an order of magnitude extension of the bandwidth through the use of multilayer coatings. The distinctive feature of this approach compared to those of other hard X-ray telescope programs is that we expect the angular resolution to be superior than telescopes made by other methods thanks to the structural integrity of the substrates. They are thin walled complete cylinders of revolution with a Wolter Type 1 figure; the front half is a parabola, the rear half a hyperbola.

  11. Nonlinear optical thin films

    NASA Technical Reports Server (NTRS)

    Leslie, Thomas M.

    1993-01-01

    A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

  12. Exchange-spring mechanism of soft and hard ferrite nanocomposites

    SciTech Connect

    Manjura Hoque, S.; Srivastava, C.; Kumar, V.; Venkatesh, N.; Das, H.N.; Saha, D.K.; Chattopadhyay, K.

    2013-08-01

    Graphical abstract: - Highlights: • Exchange-spring behaviour of soft and hard ferrites was studied. • XRD patterns indicated soft and hard ferrites as fcc and hcp structure. • Hysteresis loops indicate wide difference in coercivity of soft and hard phases. • Nanocomposites produced convex hysteresis loop characteristic of single-phase. - Abstract: The paper reports exchange-spring soft and hard ferrite nanocomposites synthesized by chemical co-precipitation with or without the application of ultrasonic vibration. The composites contained BaFe{sub 12}O{sub 19} as the hard phase and CoFe{sub 2}O{sub 4}/MgFe{sub 2}O{sub 4} as the soft phase. X-ray diffraction patterns of the samples in the optimum calcined condition indicated the presence of soft ferrites as face-centred cubic (fcc) and hard ferrites as hexagonal close packed (hcp) structure respectively. Temperature dependence of magnetization in the range of 20–700 °C demonstrated distinct presence of soft and hard ferrites as magnetic phases which are characterized by wide difference in magnetic anisotropy and coercivity. Exchange-spring mechanism led these nanocomposite systems to exchange-coupled, which ultimately produced convex hysteresis loops characteristic of a single-phase permanent magnet. Fairly high value of coercivity and maximum energy product were observed for the samples in the optimum calcined conditions with a maximum applied field of 1600 kA/m (2 T)

  13. Local structure in hard-sphere chain-molecule fluids

    NASA Astrophysics Data System (ADS)

    Wasti, Sambid; Taylor, Mark

    2012-04-01

    The conformation of a polymer chain in solvent is coupled to the local structure of the solvent environment. For hard-sphere systems, a monomeric solvent acts to compress a flexible hard-sphere-solute chain and, for a dense system, the local solvent structure is imprinted onto the chain. Here we use Monte Carlo simulation, including bond-rebridging moves, to study the size and conformation of a hard sphere chain in a hard-sphere solvent as a function of both solvent density and solvent diameter. We also study the structure of a hard-sphere-chain solute in a hard-sphere-chain solvent. In the case of a 5-mer chain in 5-mer solvent we show that the effects of solvent can be mapped to a set of two-body solvation potentials. Following our previous work on hard-sphere chains in monomeric solvent [1], we explore the application of these short chain potentials to the study of longer chain-molecule fluids. [4pt] [1] M.P. Taylor and S. Ichida, J. Polym. Sci. B: Polym. Phys. 45, 3319 (2007).

  14. Local structure in hard-sphere chain-molecule fluids

    NASA Astrophysics Data System (ADS)

    Wasti, Sambid; Taylor, Mark

    2011-10-01

    The conformation of a polymer chain in solvent is coupled to the local structure of the solvent environment. For hard-sphere systems, a monomeric solvent acts to compress a flexible hard-sphere-solute chain and, for a dense system, the local solvent structure is imprinted onto the chain. Here we use Monte Carlo simulation, including bond-rebridging moves, to study the size and conformation of a hard sphere chain in a hard-sphere solvent as a function of both solvent density and solvent diameter. We also study the structure of a hard-sphere-chain solute in a hard-sphere-chain solvent. In the case of a 5-mer chain in 5-mer solvent we show that the effects of solvent can be mapped to a set of two-body solvation potentials. Following our previous work on hard-sphere chains in monomeric solvent [1], we explore the application of these short chain potentials to the study of longer chain-molecule fluids. [4pt] [1] M.P. Taylor and S. Ichida, J. Polym. Sci. B: Polym. Phys. 45, 3319 (2007).

  15. Bead temperature effects on FCAW heat-affected zone hardness

    SciTech Connect

    Kiefer, J.H.

    1995-11-01

    Hardness limits for welding procedure qualification are often imposed to lessen the chances of delayed hydrogen cracking during production fabrication. Temper bead techniques have been used by fabricators during these qualifications to improve their chances of success. This practice involves using the heat of additional weld beads to soften the heat-affected zone (HAZ) hardness in the base metal next to the weld where the hardness is the greatest. The technique works under controlled conditions, but the consistency for field use was questionable. This report describes an investigate of the effect of welding parameters, base metal chemical composition, and weld bead placement on HAZ softening. An empirical formula developed from base plate chemical composition, weld cooling time, and temper bead placement can be used to estimate the amount of HAZ tempering. Combined with an appropriate hardness prediction formula, it can help find the welding procedure needed to achieve a desired maximum HAZ hardness, or predict the HAZ hardness of existing welds. Based on the results of the study, bead temperature is not recommended for HAZ hardness control on large scale fabrications.

  16. Rotation of hard particles in a soft matrix

    NASA Astrophysics Data System (ADS)

    Yang, Weizhu; Liu, Qingchang; Yue, Zhufeng; Li, Xiaodong; Xu, Baoxing

    Soft-hard materials integration is ubiquitous in biological materials and structures in nature and has also attracted growing attention in the bio-inspired design of advanced functional materials, structures and devices. Due to the distinct difference in their mechanical properties, the rotation of hard phases in soft matrixes upon deformation has been acknowledged, yet is lack of theory in mechanics. In this work, we propose a theoretical mechanics framework that can describe the rotation of hard particles in a soft matrix. The rotation of multiple arbitrarily shaped, located and oriented particles with perfectly bonded interfaces in an elastic soft matrix subjected to a far-field tensile loading is established and analytical solutions are derived by using complex potentials and conformal mapping methods. Strong couplings and competitions of the rotation of hard particles among each other are discussed by investigating numbers, relative locations and orientations of particles in the matrix at different loading directions. Extensive finite element analyses are performed to validate theoretical solutions and good agreement of both rotation and stress field between them are achieved. Possible extensions of the present theory to non-rigid particles, viscoelastic matrix and imperfect bonding are also discussed. Finally, by taking advantage of the rotation of hard particles, we exemplify an application in a conceptual design of soft-hard material integrated phononic crystal and demonstrate that phononic band gaps can be successfully tuned with a high accuracy through the mechanical tension-induced rotation of hard particles. The present theory established herein is expected to be of immediate interests to the design of soft-hard materials integration based functional materials, structures and devices with tunable performance via mechanical rotation of hard phases.

  17. Association of ground hardness with injuries in rugby union

    PubMed Central

    Takemura, Masahiro; Schneiders, Anthony G; Bell, Melanie L; Milburn, Peter D

    2007-01-01

    Background Ground hardness is considered one of the possible risk factors associated with rugby injuries. Objectives To examine the contribution of ground hardness, rainfall and evapotranspiration to the incidence of injury, and to investigate seasonal injury bias throughout one full season of rugby union. Methods A prospective epidemiological study of rugby injuries was performed on 271 players from rugby union teams involved in the premier grade rugby competition in Dunedin, New Zealand. Ground hardness was measured before each match over 20 rounds with an industrial penetrometer, and local weather information was collected through the National Institute of Weather and Atmospheric Research and the Otago Regional Council. Poisson mixed models were used to describe injury incidence as a function of ground hardness throughout the season. Results The overall injury incidence during the season was 52 injuries per 1000 match player‐hours (95% CI 42 to 65). Although injury incidence decreased gradually by round with a rate ratio of 0.98 (95% CI 0.96 to 0.99) (p = 0.036), and the hardness of match grounds decreased significantly over the season (0.16 MPa/round, 95% CI 0.12 to 0.21, p<0.001), a non‐significant association was demonstrated between injury incidence and ground hardness. Injury incidence was not associated with a combination of ground hardness, rainfall and evapotranspiration on the day of the match or cumulative rainfall and evapotranspiration before each match. Conclusions Seasonal change in ground hardness and an early‐season bias of injuries was demonstrated. Although the contribution of ground hardness to injury incidence was not statistically significant, match round and injury incidence were highly correlated, confirming a seasonal bias, which may confound the relationship of injury to ground condition. PMID:17504786

  18. Hard X-Ray Emission from Partially Occulted Solar Flares: RHESSI Observations in Two Solar Cycles

    NASA Astrophysics Data System (ADS)

    Effenberger, Frederic; Rubio da Costa, Fatima; Oka, Mitsuo; Saint-Hilaire, Pascal; Liu, Wei; Petrosian, Vahé; Glesener, Lindsay; Krucker, Säm

    2017-02-01

    Flares close to the solar limb, where the footpoints are occulted, can reveal the spectrum and structure of the coronal looptop source in X-rays. We aim at studying the properties of the corresponding energetic electrons near their acceleration site, without footpoint contamination. To this end, a statistical study of partially occulted flares observed with Reuven Ramaty High-Energy Solar Spectroscopic Imager is presented here, covering a large part of solar cycles 23 and 24. We perform detailed spectra, imaging, and light curve analyses for 116 flares and include contextual observations from SDO and STEREO when available, providing further insights into flare emission that were previously not accessible. We find that most spectra are fitted well with a thermal component plus a broken power-law, non-thermal component. A thin-target kappa distribution model gives satisfactory fits after the addition of a thermal component. X-ray imaging reveals small spatial separation between the thermal and non-thermal components, except for a few flares with a richer coronal source structure. A comprehensive light curve analysis shows a very good correlation between the derivative of the soft X-ray flux (from GOES) and the hard X-rays for a substantial number of flares, indicative of the Neupert effect. The results confirm that non-thermal particles are accelerated in the corona and estimated timescales support the validity of a thin-target scenario with similar magnitudes of thermal and non-thermal energy fluxes.

  19. Sealing of hard CrN and DLC coatings with atomic layer deposition.

    PubMed

    Härkönen, Emma; Kolev, Ivan; Díaz, Belén; Swiatowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe; Fenker, Martin; Toth, Lajos; Radnoczi, György; Vehkamäki, Marko; Ritala, Mikko

    2014-02-12

    Atomic layer deposition (ALD) is a thin film deposition technique that is based on alternating and saturating surface reactions of two or more gaseous precursors. The excellent conformality of ALD thin films can be exploited for sealing defects in coatings made by other techniques. Here the corrosion protection properties of hard CrN and diamond-like carbon (DLC) coatings on low alloy steel were improved by ALD sealing with 50 nm thick layers consisting of Al2O3 and Ta2O5 nanolaminates or mixtures. In cross sectional images the ALD layers were found to follow the surface morphology of the CrN coatings uniformly. Furthermore, ALD growth into the pinholes of the CrN coating was verified. In electrochemical measurements the ALD sealing was found to decrease the current density of the CrN coated steel by over 2 orders of magnitude. The neutral salt spray (NSS) durability was also improved: on the best samples the appearance of corrosion spots was delayed from 2 to 168 h. On DLC coatings the adhesion of the ALD sealing layers was weaker, but still clear improvement in NSS durability was achieved indicating sealing of the pinholes.

  20. AeSPoe HARD ROCK LABORATORY

    SciTech Connect

    Svemar, C; Pettersson, S.; Hedman, T.

    2003-02-27

    Aespoe Hard Rock Laboratory (AEHRL) has been constructed in virgin bedrock as part of the development of a deep geological repository for spent nuclear fuel in Sweden, the role being to provide input to the performance assessment, to test engineered barrier systems and to develop and refine full scale methods and machines for construction and operation of the real repository. The AEHRL extends down to 460 m depth with access via both ramp and shaft. Work in the laboratory has been separated into 4 different stage goals: (1) Verification of site investigation methods. (2) Development of detailed investigation methodology. (3) Testing of models for description of the barrier function of the host rock. (4) Demonstration of technology for and function of important parts of the repository system Stage goals 1 and 2 were in focus during the period 1986-95 and are now completed. Stage goal 1 concerns investigations carried out from ground surface and stage goal 2 investigations carried out underground, in this case during excavation of the ramp. The present work is focused on the two operative stage goals 3 and 4. The activities on barrier function of the host rock comprises primarily in-situ tests with tracer migration in natural fractures and migration of actinides in small samples of rock or bentonite inside a chemical laboratory probe installed in a borehole. The data collected from the tests are used for model development and verification. The demonstration of technology includes studies of engineered barriers and comprises tests of copper stability, bentonite buffer, backfill, plugging and practical development of the main disposal sequences. Up today five full scale deposition holes with buffer and canister, and one full-scale test of backfill and plugging have been installed. The prototype for the deposition machine is in operation. The work is conducted in an international environment and altogether eight organizations from seven countries besides Sweden take

  1. Hard Photodisintegration of Proton Pairs in {sup 3}He

    SciTech Connect

    Piasetzky, Eli; Pomerantz, Ishay; Higinbotham, D.; Strauch, S.; Gilman, R.

    2008-10-13

    Hard deuteron photodisintegration has been investigated for 20 years, as its cross section follows the constituent counting rule and it provides insight into the interplay between hadronic and quark-gluon degrees of freedom in high-momentum transfer exclusive reactions. We have now measured for the first time hard pp-pair disintegration in the reaction {gamma}{sup 3}He{yields}pp+n, using kinematics corresponding to a spectator neutron. Cross sections were measured for 90 deg. c.m. at 8 beam energies, from 0.8 to 4.7 GeV. Preliminary results will be presented and compared to the hard deuteron photodisintegration data.

  2. Dendritic Growth of Hard-Sphere Crystals. Experiment 34

    NASA Technical Reports Server (NTRS)

    Russel, W. B.; Chaikin, P. M.; Zhu, Ji-Xiang; Meyer, W. V.; Rogers, R.

    1998-01-01

    Recent observations of the disorder-order transition for colloidal hard spheres under microgravity revealed dendritic crystallites roughly 1-2 mm in size for samples in the coexistence region of the phase diagram. Order-of-magnitude estimates rationalize the absence of large or dendritic crystals under normal gravity and their stability to annealing in microgravity. A linear stability analysis of the Ackerson and Schaetzel model for crystallization of hard spheres establishes the domain of instability for diffusion-limited growth at small supersaturations. The relationship between hard-sphere and molecular crystal growth is established and exploited to relate the predicted linear instability to the well-developed dendrites observed.

  3. Future Hard X-ray and Gamma-Ray Missions

    NASA Astrophysics Data System (ADS)

    Krawczynski, Henric; Physics of the Cosmos (PCOS) Gamma Ray Science Interest Group (GammaSIG) Team

    2017-01-01

    With four major NASA and ESA hard X-ray and gamma-ray missions in orbit (Swift, NuSTAR, INTEGRAL, and Fermi) hard X-ray and gamma-ray astronomy is making major contributions to our understanding of the cosmos. In this talk, I will summarize the current and upcoming activities of the Physics of the Cosmos Gamma Ray Science Interest Group and highlight a few of the future hard X-ray and gamma-ray mission discussed by the community. HK thanks NASA for the support through the awards NNX14AD19G and NNX16AC42G and for PCOS travel support.

  4. Nano-enabled tribological thin film coatings: global patent scenario.

    PubMed

    Sivudu, Kurva S; Mahajan, Yashwant R; Joshi, Shrikant V

    2014-01-01

    The aim of this paper is to present current status and future prospects of nano-enabled tribological thin film coatings based on worldwide patent landscape analysis. The study also presents an overview of technological trends by carrying out state-of-the-art literature analysis, including survey of corporate websites. Nanostructured tribological coatings encompass a wide spectrum of nanoscale microstructures, including nanocrystalline, nanolayered, nano-multilayered, nanocomposite, nanogradient structures or their unique combinations, which are composed of single or multi-component phases. The distinct microstructural features of the coatings impart outstanding tribological properties combined with multifunctional attributes to the coated components. Their unique combination of remarkable properties make them ideal candidates for a wide range of applications in diverse fields such as cutting and metalworking tools, biomedical devices, automotive engine components, wear parts, hard disc drives etc. The patent landscape analysis has revealed that nano-enabled tribological thin film coatings have significant potential for commercial applications in view of the lion's share of corporate industry in patenting activity. The largest patent portfolio is held by Japan followed by USA, Germany, Sweden and China. The prominent players involved in this field are Mitsubishi Materials Corp., Sandvik Aktiebolag, Hitachi Ltd., Sumitomo Electric Industries Ltd., OC Oerlikon Corp., and so on. The outstanding potential of nanostructured thin film tribological coatings is yet to be fully unravelled and, therefore, immense opportunities are available in future for microstructurally engineered novel coatings to enhance their performance and functionality by many folds.

  5. Metallic glass thin films for potential biomedical applications.

    PubMed

    Kaushik, Neelam; Sharma, Parmanand; Ahadian, Samad; Khademhosseini, Ali; Takahashi, Masaharu; Makino, Akihiro; Tanaka, Shuji; Esashi, Masayoshi

    2014-10-01

    We introduce metallic glass thin films (TiCuNi) as biocompatible materials for biomedical applications. TiCuNi metallic glass thin films were deposited on the Si substrate and their structural, surface, and mechanical properties were investigated. The fabricated films showed good biocompatibility upon exposure to muscle cells. Also, they exhibited an average roughness of <0.2 nm, high wear resistance, and high mechanical properties (hardness ∼6.9 GPa and reduced modulus ∼130 GPa). Top surface of the TiCuNi films was shown to be free from Ni and mainly composed of a thin titanium oxide layer, which resulted in the high surface biocompatibility. In particular, there was no cytotoxicity effect of metallic glass films on the C2C12 myoblasts and the cells were able to proliferate well on these substrates. Low cost, viscoelastic behavior, patternability, high electrical conductivity, and the capability to coat various materials (e.g., nonbiocompatible materials) make TiCuNi as an attractive material for biomedical applications.

  6. Host thin films incorporating nanoparticles

    NASA Astrophysics Data System (ADS)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  7. A practical method to generate brilliant hard x-rays with a tabletop electron storage ring

    SciTech Connect

    Yamada, H.; Amano, D.; Miyade, H.

    1995-12-31

    With electron storage rings not only synchrotron radiation(SR) but also bremsstrahlung(BS) from a thin target placed in the electron orbit are mechanisms to generate brilliant x-ray beams. The calculated brilliance of BS with a 50 MeV storage ring, which is nearly 10{sup 13} photons/s, mrad{sup 2}, mm{sup 2}, 0.1% band width for 100 keV x-rays, exceeds that of SR from a 1 GeV storage ring. This photon energy spectrum is almost constant and extend up to the electron energy. The reasons for this high brilliance with this new radiation scheme is that the electron beams penetrating the thin target are utilized repeatedly, the narrow angular divergence of BS is determined by the kinematics of relativistic electron as same as SR, and the x-ray source size of the order of 1 {mu}m is determined by the size of thin target instead of electron beam sizes. Continuous injection of electron beam to the storage ring at full energy is the way to keep high and constant beam current. Peak current and repetition rate determine x-ray out put power. Note that the power of x-ray beam is also provided from a RF cavity of the storage ring. In this paper we will report some experimental results and discuss further application on a coherent bremsstrahlung generated from a set of stacked foils placed in the electron orbit of the ring. Resulting from these investigations the photon storage ring which is based on a 50 MeV exact circular electron storage ring could provide wide range of coherent and incoherent radiations from far infrared to hard x-ray in a practical amount of radiation power.

  8. Learning unit: Thin lenses

    NASA Astrophysics Data System (ADS)

    Nita, L.-S.

    2012-04-01

    Learning unit: Thin lenses "Why objects seen through lenses are sometimes upright and sometimes reversed" Nita Laura Simona National College of Arts and Crafts "Constantin Brancusi", Craiova, Romania 1. GEOMETRIC OPTICS. 13 hours Introduction (models, axioms, principles, conventions) 1. Thin lenses (Types of lenses. Defining elements. Path of light rays through lenses. Image formation. Required physical quantities. Lens formulas). 2. Lens systems (Non-collated lenses. Focalless systems). 3. Human eye (Functioning as an optical system. Sight defects and their corrections). 4. Optical instruments (Characteristics exemplified by a magnifying glass. Paths of light rays through a simplified photo camera. Path of light rays through a classical microscope) (Physics curriculum for the IXth grade/ 2011). This scenario exposes a learning unit based on experimental sequences (defining specific competencies), as a succession of lessons started by noticing a problem whose solution assumes the setup of an experiment under laboratory conditions. Progressive learning of theme objectives are realised with sequential experimental steps. The central cognitive process is the induction or the generalization (development of new knowledge based on observation of examples or counterexamples of the concept to be learnt). Pupil interest in theme objectives is triggered by problem-situations, for example: "In order to better see small objects I need a magnifying glass. But when using a magnifier, small object images are sometimes seen upright and sometimes seen reversed!" Along the way, pupils' reasoning will converge to the idea: "The image of an object through a lens depends on the relative distances among object, lens, and observer". Associated learning model: EXPERIMENT Specific competencies: derived from the experiment model, in agreement with the following learning unit steps I. Evoking - Anticipation: Size of the problem, formulation of hypotheses and planning of experiment. II

  9. On the reconciliation of simultaneous microwave imaging and hard X-ray observations of a solar flare

    NASA Technical Reports Server (NTRS)

    Nitta, N.; White, S. M.; Schmahl, E. J.; Kundu, M. R.

    1991-01-01

    Microwave imaging data for a small flare with simultaneous hard X-ray spectral observations are compared. The X-ray data suggest that the power-law index delta of the energy distribution of the radiating electrons is 5.3 (thick-target) which differs significantly from the estimate (delta = 1.4) from a homogeneous optically-thin gyrosynchrotron model which fits the radio observations well. In order to reconcile these results, a double power-law energy spectrum is investigated for the energetic electrons in the flare, as assumed by other authors: the power law is steep at low energies and much flatter at the higher energies which produce the bulk of the microwaves. The emission of soft photons by the flat tail strongly contributes to the observed hard X-ray range and would flatten the spectrum there. A thin-target model for the X-ray emission is also inconsistent with radio data. An inhomogenous gyrosychrotron model with a number of free parameters and containing an electron distribution given by the thick-target X-ray model could be made to fit the radio data.

  10. USE OF FUME SUPPRESSANTS IN HARD CHROMIUM BATHS - QUALITY TESTING

    EPA Science Inventory

    The EPA Common Sense Initiative (CSI) is a cooperative effort of government, industry, environmental and other stakeholder groups to find "cleaner, cheaper, smarter" approaches to environmental management in industrial sectors. The purpose of the project is to help hard chromium ...

  11. 12. Hard HF transmitter antenna, view toward west. Lyon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Hard HF transmitter antenna, view toward west. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  12. 11. Hard HF receiver antenna, view towards east. Lyon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Hard HF receiver antenna, view towards east. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  13. USE OF FUME SUPPRESSANTS IN HARD CHROMIUM BATHS - EMISSION TESTING

    EPA Science Inventory

    The EPA Common Sense Initiative (CSI) is a cooperative effort of government, industry, environmental, and other stakeholder groups to find "cleaner, cheaper, smarter" approaches to environmental management in industrial sectors. The purpose of the project is to assist hard chrome...

  14. Remote hard copy. Volume 3. Systems programming manual

    SciTech Connect

    Simons, R.W.

    1980-03-01

    The software used to operate and maintain the remote hard copy is described. All operating software that runs in the NOVA minicomputers is covered as are various utility and diagnostic programs used for creating and checking this software. 2 figures.

  15. Micromagnetic simulations with periodic boundary conditions: Hard-soft nanocomposites

    SciTech Connect

    Wysocki, Aleksander L.; Antropov, Vladimir P.

    2016-12-01

    Here, we developed a micromagnetic method for modeling magnetic systems with periodic boundary conditions along an arbitrary number of dimensions. The main feature is an adaptation of the Ewald summation technique for evaluation of long-range dipolar interactions. The method was applied to investigate the hysteresis process in hard-soft magnetic nanocomposites with various geometries. The dependence of the results on different micromagnetic parameters was studied. We found that for layered structures with an out-of-plane hard phase easy axis the hysteretic properties are very sensitive to the strength of the interlayer exchange coupling, as long as the spontaneous magnetization for the hard phase is significantly smaller than for the soft phase. The origin of this behavior was discussed. Additionally, we investigated the soft phase size optimizing the energy product of hard-soft nanocomposites.

  16. Micromagnetic simulations with periodic boundary conditions: Hard-soft nanocomposites

    NASA Astrophysics Data System (ADS)

    Wysocki, Aleksander L.; Antropov, Vladimir P.

    2017-04-01

    We developed a micromagnetic method for modeling magnetic systems with periodic boundary conditions along an arbitrary number of dimensions. The main feature is an adaptation of the Ewald summation technique for evaluation of long-range dipolar interactions. The method was applied to investigate the hysteresis process in hard-soft magnetic nanocomposites with various geometries. The dependence of the results on different micromagnetic parameters was studied. We found that for layered structures with an out-of-plane hard phase easy axis the hysteretic properties are very sensitive to the strength of the interlayer exchange coupling, as long as the spontaneous magnetization for the hard phase is significantly smaller than for the soft phase. The origin of this behavior was discussed. Additionally, we investigated the soft phase size optimizing the energy product of hard-soft nanocomposites.

  17. Hard-real-time resource management for autonomous spacecraft

    NASA Technical Reports Server (NTRS)

    Gat, E.

    2000-01-01

    This paper describes tickets, a computational mechanism for hard-real-time autonomous resource management. Autonomous spacecraftcontrol can be considered abstractly as a computational process whose outputs are spacecraft commands.

  18. CAPSULE REPORT: HARD CHROME FUME SUPPRESSANTS & CONTROL TECHNOLOGIES

    EPA Science Inventory

    All existing information which includes the information extrapolated from the Hard Chrome Pollution Prevention Demonstration Project(s) and other sources derived from plating facilities and industry contacts, will be condensed and featured in this document. At least five chromium...

  19. 35. Perimeter acquisition radar building room #325, showing hard disc ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. Perimeter acquisition radar building room #325, showing hard disc drive - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  20. Prepulse dependence in hard x-ray generation from microdroplets

    SciTech Connect

    Anand, M.; Kahaly, S.; Kumar, G. Ravindra; Sandhu, A. S.; Gibbon, P.; Krishnamurthy, M.

    2006-04-07

    We report on experiments which show that liquid microdroplets are very efficient in hard x-ray generation. We make a comparative study of hard x-ray emission from 15 {mu}m methanol microdroplets and a plain slab target of similar atomic composition at similar laser intensities. The hard X-ray yield from droplet plasmas is about 35 times more than that obtained from solid plasmas. A prepulse that is about 10ns and at least 2% in intensity of the main pulse is essential for hard x-ray generation from the droplets at about 1015 W cm-2. A hot electron temperature of 36 keV is measured from the droplets at 8 x 1014 W cm-2; three times higher intensity is needed to obtain similar hot electron temperature from solid plasmas that have similar atomic composition. We use 1D-PIC simulation to obtain qualitative correlation to the experimental observations.

  1. Hardness and Microstructure of Binary and Ternary Nitinol Compounds

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.

    2016-01-01

    The hardness and microstructure of twenty-six binary and ternary Nitinol (nickel titanium, nickel titanium hafnium, nickel titanium zirconium and nickel titanium tantalum) compounds were studied. A small (50g) ingot of each compound was produced by vacuum arc remelting. Each ingot was homogenized in vacuum for 48 hr followed by furnace cooling. Specimens from the ingots were then heat treated at 800, 900, 1000 or 1100 degree C for 2 hr followed by water quenching. The hardness and microstructure of each specimen was compared to the baseline material (55-Nitinol, 55 at.% nickel - 45 at.% titanium, after heat treatment at 900 degC). The results show that eleven of the studied compounds had higher hardness values than the baseline material. Moreover, twelve of the studied compounds had measured hardness values greater 600HV at heat treatments from 800 to 900 degree C.

  2. Chiral atomically thin films.

    PubMed

    Kim, Cheol-Joo; Sánchez-Castillo, A; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm(-1)) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  3. Chiral atomically thin films

    NASA Astrophysics Data System (ADS)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm-1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  4. Thin film strain transducer

    NASA Astrophysics Data System (ADS)

    Rand, J. L.

    1981-01-01

    Previous attempts to develop an appropriate sensor for measuring the stress or strain of high altitude balloons during flight are reviewed as well as the various conditions that must be met by such a device. The design, development and calibration of a transducer which promises to satisfy the necessary design constraints are described. The thin film strain transducer has a low effective modulus so as not to interfere with the strain that would naturally occur in the balloon. In addition, the transducer has a high sensitivity to longitudinal strain (7.216 mV/V/unit strain) which is constant for all temperature from room temperature to -80 C and all strains from 5 percent compression to 10 percent tensile strain. At the same time, the sensor is relatively insensitive (0.27 percent) to transverse forces. The device has a standard 350 ohm impedance which is compatible with available bridge balance, amplification and telemetry instrumentation now available for balloon flight. Recommendations are included for improved coatings to provide passive thermal control as well as model, tethered and full scale flight testing.

  5. The magnetic properties and microstructure of Co-Pt thin films using wet etching process.

    PubMed

    Lee, Chang-Hyoung; Cho, Young-Lae; Lee, Won-Pyo; Suh, Su-Jeong

    2014-11-01

    Perpendicular magnetic recording (PMR) is a promising candidate for high density magnetic recording and has already been applied to hard disk drive (HDD) systems. However, media noise still limits the recording density. To reduce the media noise and achieve a high signal-to-noise ratio (SNR) in hard disk media, the grains of the magnetic layer must be magnetically isolated from each other. This study examined whether sputter-deposited Co-Pt thin films can have adjacent grains that are physically isolated. To accomplish this, the effects of the sputtering conditions and wet etching process on magnetic properties and the microstructure of the films were investigated. The film structure was Co-Pt (30 nm)/Ru (30 nm)/NiFe (10 nm)/Ta (5 nm). The composition of the Co-Pt thin films was Co-30.7 at.% Pt. The Co-Pt thin films were deposited in Ar gas at 5, 10, 12.5, and 15 mTorr. Wet etching process was performed using 7% nitric acid solution at room temperature. These films had high out-of-plane coercivity of up to 7032 Oe, which is twice that of the as-deposited film. These results suggest that wet etched Co-Pt thin films have weaker exchange coupling and enhanced out-of-plane coercivity, which would reduce the medium noise.

  6. Perpendicular recording media for hard disk drives

    NASA Astrophysics Data System (ADS)

    Piramanayagam, S. N.

    2007-07-01

    Perpendicular recording technology has recently been introduced in hard disk drives for computer and consumer electronics applications. Although conceptualized in the late 1970s, making a product with perpendicular recording that has competing performance, reliability, and price advantage over the prevalent longitudinal recording technology has taken about three decades. One reason for the late entry of perpendicular recording is that the longitudinal recording technology was quite successful in overcoming many of its problems and in staying competitive. Other reasons are the risks, problems, and investment needed in making a successful transition to perpendicular recording technology. Iwasaki and co-workers came up with many inventions in the late 1970s, such as single-pole head, CoCr alloy media with a perpendicular anisotropy, and recording media with soft magnetic underlayers [S. Iwasaki and K. Takemura, IEEE Trans. Magn. 11, 1173 (1975); S. Iwasaki and Y. Nakamura, IEEE Trans. Magn. 14, 436 (1978); S. Iwasaki, Y. Nakamura, and K. Ouchi, IEEE Trans. Magn. 15, 1456 (1979)]. Nevertheless, the research on perpendicular recording media has been intense only in the past five years or so. The main reason for the current interest comes from the need to find an alternative technology to get away from the superparamagnetic limit faced by the longitudinal recording. Out of the several recording media materials investigated in the past, oxide based CoCrPt media have been considered a blessing. The media developed with CoCrPt-oxide or CoCrPt -SiO2 have shown much smaller grain sizes, lower noise, and larger thermal stability than the perpendicular recording media of the past, which is one of the reasons for the success of perpendicular recording. Moreover, oxide-based perpendicular media have also overtaken the current longitudinal recording media in terms of better recording performance. Several issues that were faced with the soft underlayers have also been solved by the

  7. Hard ellipses: Equation of state, structure, and self-diffusion.

    PubMed

    Xu, Wen-Sheng; Li, Yan-Wei; Sun, Zhao-Yan; An, Li-Jia

    2013-07-14

    Despite their fundamental and practical interest, the physical properties of hard ellipses remain largely unknown. In this paper, we present an event-driven molecular dynamics study for hard ellipses and assess the effects of aspect ratio and area fraction on their physical properties. For state points in the plane of aspect ratio (1 ≤ k ≤ 9) and area fraction (0.01 ≤ φ ≤ 0.8), we identify three different phases, including isotropic, plastic, and nematic states. We analyze in detail the thermodynamic, structural, and self-diffusive properties in the formed various phases of hard ellipses. The equation of state (EOS) is shown for a wide range of aspect ratios and is compared with the scaled particle theory (SPT) for the isotropic states. We find that SPT provides a good description of the EOS for the isotropic phase of hard ellipses. At large fixed φ, the reduced pressure p increases with k in both the isotropic and the plastic phases and, interestingly, its dependence on k is rather weak in the nematic phase. We rationalize the thermodynamics of hard ellipses in terms of particle motions. The static structures of hard ellipses are then investigated both positionally and orientationally in the different phases. The plastic crystal is shown to form for aspect ratios up to k = 1.4, while appearance of the stable nematic phase starts approximately at k = 3. We quantitatively determine the locations of the isotropic-plastic (I-P) transition and the isotropic-nematic (I-N) transition by analyzing the bond-orientation correlations and the angular correlations, respectively. As expected, the I-P transition point is found to increase with k, while a larger k leads to a smaller area fraction where the I-N transition takes place. Moreover, our simulations strongly support that the two-dimensional nematic phase in hard ellipses has only quasi-long-range orientational order. The self-diffusion of hard ellipses is further explored and connections are revealed between

  8. The Hard X-Ray Sky: Recent Observational Progress

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Cannizzo, John K.

    2010-01-01

    The last fifty years have witnessed the birth, development, and maturation to full potential of hard X-ray astrophysics. The primary force driving the history of the field has been the development of space-based instrumentation optimized for getting the maximum science out of observations of high-energy photons from astrophysical sources. Hard X-ray telescopes are leading research in areas such as galactic diffuse emission, galactic transients, and active galactic nuclei.

  9. Improvement in hardness of soda-lime-silica glass

    NASA Astrophysics Data System (ADS)

    Chakraborty, Riya; De, Moumita; Roy, Sudakshina; Dey, Arjun; Biswas, Sampad K.; Middya, Tapas Ranjan; Mukhopadhyay, Anoop K.

    2012-06-01

    Hardness is a key design parameter for structural application of brittle solids like glass. Here we report for the first time the significant improvement of about 10% in Vicker's hardness of a soda-lime-silica glass with loading rate in the range of 0.1-10 N.s-1. Corroborative dark field optical and scanning electron microscopy provided clue to this improvement through evidence of variations in spatial density of shear deformation band formation as a function of loading rate.

  10. The Hard X-ray Sky: Recent Observational Progress

    SciTech Connect

    Gehrels, Neil

    2009-05-11

    The last fifty years have witnessed the birth, development, and maturation to full potential of hard X-ray astrophysics. The primary force driving the history of the field has been the development of space-based instrumentation optimized for getting the maximum science out of observations of high-energy photons from astrophysical sources. Hard X-ray telescopes are leading research in areas such as galactic diffuse emission, galactic transients, and active galactic nuclei.

  11. Subgroup report on hard x-ray microprobes

    SciTech Connect

    Ice, G.E.; Barbee, T.; Bionta, R.; Howells, M.; Thompson, A.C.; Yun, W.

    1994-09-01

    The increasing availability of synchrotron x-ray sources has stimulated the development of advanced hard x-ray (E{>=}5 keV) microprobes. New x-ray optics have been demonstrated which show promise for achieving intense submicron hard x-ray probes. These probes will be used for extraordinary elemental detection by x-ray fluorescence/absorption and for microdiffraction to identify phase and strain. The inherent elemental and crystallographic sensitivity of an x-ray microprobe and its inherently nondestructive and penetrating nature makes the development of an advanced hard x-ray microprobe an important national goal. In this workshop state-of-the-art hard x-ray microprobe optics were described and future directions were discussed. Gene Ice, Oak Ridge National Laboratory (ORNL), presented an overview of the current status of hard x-ray microprobe optics and described the use of crystal spectrometers to improve minimum detectable limits in fluorescent microprobe experiments. Al Thompson, Lawrence Berkeley Laboratory (LBL), described work at the Center for X-ray Optics to develop a hard x-ray microprobe based on Kirkpatrick-Baez (KB) optics. Al Thompson also showed the results of some experimental measurements with their KB optics. Malcolm Howells presented a method for bending elliptical mirrors and Troy Barbee commented on the use of graded d spacings to achieve highest efficiency in KB multilayer microfocusing. Richard Bionta, Lawrence Livermore National Laboratory (LLNL), described the development of the first hard x-ray zone plates and future promise of so called {open_quotes}jelly roll{close_quotes} or sputter slice zone plates. Wenbing Yun, Argonne National Laboratory (ANL), described characterization of jelly roll and lithographically produced zone plates and described the application of zone plates to focus extremely narrow bandwidths by nuclear resonance. This report summarizes the presentations of the workshop subgroup on hard x-ray microprobes.

  12. Semi empirical hardness predictive model for AZ91 nanocomposite

    NASA Astrophysics Data System (ADS)

    Zaidi, N. H. A.; Jamaludin, S. B.; Zaidi, A. M. A.; Ahmad, K. R.

    2016-07-01

    AZ91 nanocomposite was exposed to several heat treatment processes and the effect of precipitation hardening on hardness was studied as a function of time and temperature. The investigation shows the significant of time and temperature are the main role in the precipitation hardening process of the nanocomposite. Kinetics study show a deceptive activation energy of 21 kJ/mol of the AZ91 nanocomposite. A relationship was derived to predict the maximum hardness at given time and temperature.

  13. Hard water softening effect of a baby cleanser

    PubMed Central

    Walters, Russel M; Anim-Danso, Emmanuel; Amato, Stephanie M; Capone, Kimberly A; Mack, M Catherine; Telofski, Lorena S; Mays, David A

    2016-01-01

    Background Hard water is associated with atopic dermatitis (eczema). We wanted to determine if a baby cleanser and its individual components altered free ionized calcium (Ca2+) in a simulated hard water baby bath. For these studies, an in vitro determination of free Ca2+ in a simulated hard water baby bath, and an in vivo exploratory study of free Ca2+ absorption into skin from hard water were performed. Methods Free Ca2+ was measured with an ion-sensitive electrode in vitro in hard water (100–500 ppm, Ca2+) before and after addition of the cleanser and/or its components. In an exploratory study, absorption of Ca2+ into skin from hard water was determined in three female participants (aged 21–29 years). Results At an in-use dilution of 1%, the test cleanser reduced free Ca2+ from ~500 ppm to <200 ppm; a 10% in-use dilution bound virtually all free Ca2+. The anionic surfactant component contributed the most to this effect. In the exploratory in vivo study, we measured a reduction of ~15% in free Ca2+ from simulated hard water over 10 minutes. Conclusion Baby cleansers can bind free Ca2+ and reduce the effective water hardness of bath water. Reducing the amount of free Ca2+ in the water will reduce the availability of the ion for binding to the skin. Altering or reducing free Ca2+ concentrations in bath water may be an important parameter in creating the ideal baby bath. PMID:27789967

  14. Palaeoecology and evolution of marine hard substrate communities

    NASA Astrophysics Data System (ADS)

    Taylor, P. D.; Wilson, M. A.

    2003-07-01

    Marine organisms have occupied hard substrates since the Archaean. Shells, rocks, wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments, but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space. Hard substrate communities are formed by organisms with a variety of strategies for adhering to and/or excavating the substrates they inhabit. While mobile grazers, organically attached and even soft-bodied organisms may leave evidence of their former presence in ancient hard substrate communities, a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils. Furthermore, encrusters and borers are preserved in situ, retaining their spatial relationships to one another and to the substrate. Spatial competition, ecological succession, oriented growth, and differential utilisation of exposed vs. hidden substrate surfaces can all be observed or inferred. Hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years. Here we review the research on modern and ancient hard substrate communities, and point to some changes that have affected them over geological time scales. Such changes include a general increase in bioerosion of hard substrates, particularly carbonate surfaces, through the Phanerozoic. This is, at least in part, analogous to the infaunalisation trends seen in soft substrate communities. Encrusting forms show an increase in skeletalisation from the Palaeozoic into the Mesozoic and Cenozoic, which may be a response to increasing levels of predation. Hard substrate communities, considering borers and encrusters together, show a rough increase in tiering through the Phanerozoic which again parallels trends seen in soft substrate communities. This extensive review of the literature on living and fossil hard substrate organisms shows that

  15. Test bench development for the radiation Hard GBTX ASIC

    NASA Astrophysics Data System (ADS)

    Leitao, P.; Feger, S.; Porret, D.; Baron, S.; Wyllie, K.; Barros Marin, M.; Figueiredo, D.; Francisco, R.; Da Silva, J. C.; Grassi, T.; Moreira, P.

    2015-01-01

    This paper presents the development of the GBTX radiation hard ASIC test bench. Developed for the LHC accelerator upgrade programs, the GBTX implements a bidirectional 4.8 Gb/s link between the radiation hard on-detector custom electronics and the off-detector systems. The test bench was used for functional testing of the GBTX and to evaluate its performance in a radiation environment, by conducting Total Ionizing Dose and Single-Event Upsets tests campaigns.

  16. Reliability Design to Circuit System in Hard Target Smart Fuze

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhang, Ya

    Hard target smart fuze can adaptively control the the burst point of penetrating projectile. How to improve its circuit working reliability to fit the fuze harsh high-g working environment is studied in this paper. A series of practical measures are taken, such as, propose buffer to fuze circuits; use high quality electronic components; and take circuit redundancy technique. Then the conclusions will provide valuable reference for engineering applications of hard target smart fuze.

  17. The space-time structure of hard scattering processes

    SciTech Connect

    J.-M. Laget

    2004-09-01

    Recent studies of exclusive electroproduction of vector mesons at JLab make it possible for the first time to play with two independent hard scales: the virtuality Q{sup 2}2 of the photon, which sets the observation scale, and the momentum transfer t to the hadronic system, which sets the interaction scale. They reinforce the description of hard scattering processes in terms of few effective degrees of freedom relevant to the Jlab-Hermes energy range.

  18. Caring for patients who are deaf or hard of hearing.

    PubMed

    Brown, Heather L; Hughes-Bell, Aileen; McDuffie, Anna W

    2015-12-01

    Patients who are deaf and hard of hearing often find the American healthcare system to be inaccessible due to communication barriers. This article describes facilities' and providers' requirements under the Americans with Disabilities Act to provide qualified interpreters and other assistive devices to patients who are deaf or hard of hearing. Removing communication barriers can protect healthcare providers from potential legal action and lets them deliver consistent, quality healthcare to all patients.

  19. Glass formation in a mixture of hard disks and hard ellipses.

    PubMed

    Xu, Wen-Sheng; Duan, Xiaozheng; Sun, Zhao-Yan; An, Li-Jia

    2015-06-14

    We present an event-driven molecular dynamics study of glass formation in two-dimensional binary mixtures composed of hard disks and hard ellipses, where both types of particles have the same area. We demonstrate that characteristic glass-formation behavior appears upon compression under appropriate conditions in such systems. In particular, while a rotational glass transition occurs only for the ellipses, both types of particles undergo a kinetic arrest in the translational degrees of freedom at a single density. The translational dynamics for the ellipses is found to be faster than that for the disks within the same system, indicating that shape anisotropy promotes the translational motion of particles. We further examine the influence of mixture's composition and aspect ratio on the glass formation. For the mixtures with an ellipse aspect ratio of k = 2, both translational and rotational glass transition densities decrease with increasing the disk concentration at a similar rate, and hence, the two glass transitions remain close to each other at all concentrations investigated. By elevating k, however, the rotational glass transition density diminishes at a faster rate than the translational one, leading to the formation of an orientational glass for the ellipses between the two transitions. Our simulations imply that mixtures of particles with different shapes emerge as a promising model for probing the role of particle shape in determining the properties of glass-forming liquids. Furthermore, our work illustrates the potential of using knowledge concerning the dependence of glass-formation properties on mixture's composition and particle shape to assist in the rational design of amorphous materials.

  20. Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers

    SciTech Connect

    Best, James P. E-mail: engelbert.redel@kit.edu Michler, Johann; Maeder, Xavier; Liu, Jianxi; Wang, Zhengbang; Tsotsalas, Manuel; Liu, Jinxuan; Gliemann, Hartmut; Weidler, Peter G.; Redel, Engelbert E-mail: engelbert.redel@kit.edu Wöll, Christof E-mail: engelbert.redel@kit.edu; Röse, Silvana; Oberst, Vanessa; Walheim, Stefan

    2015-09-07

    Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (E{sub ITO} ≈ 96.7 GPa, E{sub HKUST−1} ≈ 22.0 GPa). For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.

  1. a Brief Survey on Basic Properties of Thin Films for Device Application

    NASA Astrophysics Data System (ADS)

    Rao, M. C.; Shekhawat, M. S.

    Thin film materials are the key elements of continued technological advances made in the fields of optoelectronic, photonic and magnetic devices. Thin film studies have directly or indirectly advanced many new areas of research in solid state physics and chemistry which are based on phenomena uniquely characteristic of the thickness, geometry and structure of the film. The processing of materials into thin films allows easy integration into various types of devices. Thin films are extremely thermally stable and reasonably hard, but they are fragile. On the other hand organic materials have reasonable thermal stability and are tough, but are soft. Thin film mechanical properties can be measured by tensile testing of freestanding films and by the micro beam cantilever deflection technique, but the easiest way is by means of nanoindentation. Optical experiments provide a good way of examining the properties of semiconductors. Particularly measuring the absorption coefficient for various energies gives information about the band gaps of the material. Thin film materials have been used in semiconductor devices, wireless communications, telecommunications, integrated circuits, rectifiers, transistors, solar cells, light-emitting diodes, photoconductors and light crystal displays, lithography, micro- electromechanical systems (MEMS) and multifunctional emerging coatings, as well as other emerging cutting technologies.

  2. Nanomechanical and microstructural characterization of sputter deposited ZnO thin films

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Vipul; Chowdhury, Rajib; Jayaganthan, R.

    2016-12-01

    The nano-mechanical properties of ZnO thin films deposited at different substrate temperature such as (RT) 25 °C, 100 °C, 200 °C, and 300 °C using DC-sputtering on Corning glass substrate were investigated. The ZnO thin films are found to be predominately c-axis (002) oriented. The crystal structure is sensitive to increasing substrate temperature and new set of crystal planes become visible at 300 °C as thin films become highly polycrystalline. The presence of (103) crystal plane is more pronounced with the increasing substrate temperature. However, high crystallinity and peak intensity ratio I(002)/I(103) (counts) is highest for thin films deposited at 100 °C, which is attributed for high hardness and better adhesive properties observed for ZnO thin films. Concomitantly, no major sudden burst of displacement 'pop-in' event in load-displacement curve of thin films observed during indentation, indicating the films are dense with low defects and adhered strongly to the substrate.

  3. Structure property relationships of nitride superlattice hard coatings prepared by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Patel, Nitin

    Today, more than 40% of all cutting tools used in machining applications are covered with coatings. Coatings improve wear resistance, increase tool life, enable use at higher speed, and broaden the application range. Superlattices, where thin layers (typically <10 nm) of two different materials (e.g. TiN and AlN) are deposited in an alternating fashion, are widely used commercially. Importantly, the hardness value of a superlattice (e.g. TiN/AlN) can significantly exceed the rule of mixture value. Superlattice coatings built from crystallographically dissimilar materials are not widely studied but hold promise for improvements in performance by allowing for both hardness and toughness to be simultaneously optimized. This is what this thesis is concerned with: a structure-property comparison of isostructural superlattices with corresponding non-isostructural superlattices. In order to grow both isostructural and non-isostructural superlattices from the same set of materials, it is necessary to grow monolithic films in different phases. Towards this end, the synthesis of different phases of AlN, (Ti,Al)N, TaN, and TiN was investigated. Films were grown by pulsed laser deposition in two different chambers that had different base pressures to study the effect of background gases on the phases and orientations of the films. Growth of AlN and (Ti,Al)N films is strongly affected in a chamber that had a base pressure of 10-6 Torr, but the films adopt their stable nitride structures in a chamber with the lower base pressure of 10-8 Torr. TaN adopts either the cubic rock salt structure or its stable hexagonal structure, depending on the growth temperature, while TiN grows as rock salt in all conditions. Single crystal epitaxial superlattices were then grown with different compositions, periodicities, and crystallographic orientations to compare the effect of chemistry, nanostructure, and crystallographic texture on hardness. Finally, the structure-property relationships of

  4. Factors that Influence the Formation and Stability of Thin, Cryo-EM Specimens

    PubMed Central

    Glaeser, Robert M.; Han, Bong-Gyoon; Csencsits, Roseann; Killilea, Alison; Pulk, Arto; Cate, Jamie H.D.

    2016-01-01

    Poor consistency of the ice thickness from one area of a cryo-electron microscope (cryo-EM) specimen grid to another, from one grid to the next, and from one type of specimen to another, motivates a reconsideration of how to best prepare suitably thin specimens. Here we first review the three related topics of wetting, thinning, and stability against dewetting of aqueous films spread over a hydrophilic substrate. We then suggest that the importance of there being a surfactant monolayer at the air-water interface of thin, cryo-EM specimens has been largely underappreciated. In fact, a surfactant layer (of uncontrolled composition and surface pressure) can hardly be avoided during standard cryo-EM specimen preparation. We thus suggest that better control over the composition and properties of the surfactant layer may result in more reliable production of cryo-EM specimens with the desired thickness. PMID:26386606

  5. Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity

    SciTech Connect

    Jamison, Ryan Dale; Shen, Yu -Lin

    2015-08-13

    Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayer material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.

  6. Fabrication and properties of strip casting 4.5 wt% Si steel thin sheet

    NASA Astrophysics Data System (ADS)

    Zu, Guoqing; Zhang, Xiaoming; Zhao, Jingwei; Wang, Yuqian; Yan, Yi; Li, Chengang; Cao, Guangming; Jiang, Zhengyi

    2017-02-01

    Three 4.5 wt% Si steel thin sheets with different thicknesses were efficiently fabricated by twin-roll strip casting, warm rolling and cold rolling followed by final annealing. A comprehensive investigation from the workability of the as-cast strip to the magnetic property of the produces was performed to illustrate the superiority of the new materials. The results show that the as-cast strip, which has a much lower Vickers hardness than that of the 6.5 wt% Si steel, is suitable for rolling processing. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirm that no ordering phase exists in the as-cast strip. The cold-rolled thin sheets exhibit good surface quality without edge cracks. Furthermore, all the three 4.5 wt% Si steel thin sheets possess relative strong <100>//ND texture and present high magnetic inductions and low iron losses after finial annealing.

  7. Analytic limits on the forms of spectra possible from optically thin collisional bremsstrahlung source models

    NASA Technical Reports Server (NTRS)

    Brown, John C.; Emslie, A. Gordon

    1988-01-01

    The constraints on hard X-ray bremsstrahlung spectral forms required in order for them to correspond to physically acceptable (nonnegative) electron distributions in thin-target, thick-target, and thermal source models are discussed. The extent to which various spectra can be attributed to the different models is examined, showing that many possible spectra cannot be described by all, or in some cases, any of the models. It is shown that for any bremsstrahlung cross section, the thick-target and thermal models require that successively higher derivatives of the thin-target constraint have the appropriate sign. It is found that thermal models are the most restrictive, and that thin-target models are the least restrictive. Explicit analytic constraint expressions are derived for all three cases for the Kramers cross section and examples of acceptable and unacceptable spectra are given. Application of these criteria to the testing and exclusion of models is discussed.

  8. Segregation of Fluidized Binary Hard-Sphere Systems Under Gravity

    NASA Astrophysics Data System (ADS)

    Kim, Soon-Chul

    We have derived an analytic expression for the contact value of the local density of binary hard-sphere systems under gravity. We have obtained the crossover conditions for the Brazil-nut type segregation of binary hard-sphere mixtures and binary hard-sphere chain mixtures from the segregation criterion, where the segregation occurs when the density (or the pressure) of the small spheres at the bottom is higher than that of the large spheres, or vice versa. For the binary hard-sphere chain mixtures, the crossover condition for the segregation depends on the number of monomers composed of hard-sphere chains as well as the mass and the diameter of each species. The fundamental-measure theories (FMTs) and local density approximation (LDA) are employed to examine the crossover condition for the segregation of the gravity-induced hard-sphere mixtures. The calculated results show that the LDA does not explain the density oscillation near the bottom, whereas the modified fundamental-measure theory (MFMT) compares with molecular dynamics simulations.

  9. Hard Braking Events Among Novice Teenage Drivers By Passenger Characteristics

    PubMed Central

    Simons-Morton, Bruce G.; Ouimet, Marie Claude; Wang, Jing; Klauer, Sheila G.; Lee, Suzanne E.; Dingus, Thomas A.

    2010-01-01

    Summary In a naturalistic study of teenage drivers (N = 42) hard braking events of ≤−0.45 g were assessed over the first 6 months of licensure. A total of 1,721 hard braking events were recorded. The video footage of a sample (816) of these events was examined to evaluate validity and reasons for hard braking. Of these, 788 (96.6%) were estimated valid, of which 79.1% were due to driver misjudgment, 10.8% to risky driving behavior, 5.3% to legitimate evasive maneuvers, and 4.8% to distraction. Hard braking events per 10 trips and per 100 miles were compared across passenger characteristics. Hard braking rates per 10 trips among newly licensed teenagers during the first 6 months of licensure were significantly higher when driving with teen passengers and lower with adult passengers than driving alone; rates per 100 miles were lower with adult passengers than with no passengers. Further examination of the results indicates that rates of hard braking with teenage passengers were significantly higher compared with no passengers: 1) for male drivers; 2) during the first month of licensure. The data suggest that that novice teenage driving performance may not be as good or safe when driving alone or with teenage passengers than with adult passengers and provide support for the hypothesis that teenage passengers increase driving risks, particularly during the first month of licensure. PMID:21243109

  10. Hard Braking Events Among Novice Teenage Drivers By Passenger Characteristics.

    PubMed

    Simons-Morton, Bruce G; Ouimet, Marie Claude; Wang, Jing; Klauer, Sheila G; Lee, Suzanne E; Dingus, Thomas A

    2009-06-22

    In a naturalistic study of teenage drivers (N = 42) hard braking events of ≤-0.45 g were assessed over the first 6 months of licensure. A total of 1,721 hard braking events were recorded. The video footage of a sample (816) of these events was examined to evaluate validity and reasons for hard braking. Of these, 788 (96.6%) were estimated valid, of which 79.1% were due to driver misjudgment, 10.8% to risky driving behavior, 5.3% to legitimate evasive maneuvers, and 4.8% to distraction. Hard braking events per 10 trips and per 100 miles were compared across passenger characteristics. Hard braking rates per 10 trips among newly licensed teenagers during the first 6 months of licensure were significantly higher when driving with teen passengers and lower with adult passengers than driving alone; rates per 100 miles were lower with adult passengers than with no passengers. Further examination of the results indicates that rates of hard braking with teenage passengers were significantly higher compared with no passengers: 1) for male drivers; 2) during the first month of licensure. The data suggest that that novice teenage driving performance may not be as good or safe when driving alone or with teenage passengers than with adult passengers and provide support for the hypothesis that teenage passengers increase driving risks, particularly during the first month of licensure.

  11. Mongoose: Creation of a Rad-Hard MIPS R3000

    NASA Technical Reports Server (NTRS)

    Lincoln, Dan; Smith, Brian

    1993-01-01

    This paper describes the development of a 32 Bit, full MIPS R3000 code-compatible Rad-Hard CPU, code named Mongoose. Mongoose progressed from contract award, through the design cycle, to operational silicon in 12 months to meet a space mission for NASA. The goal was the creation of a fully static device capable of operation to the maximum Mil-883 derated speed, worst-case post-rad exposure with full operational integrity. This included consideration of features for functional enhancements relating to mission compatibility and removal of commercial practices not supported by Rad-Hard technology. 'Mongoose' developed from an evolution of LSI Logic's MIPS-I embedded processor, LR33000, code named Cobra, to its Rad-Hard 'equivalent', Mongoose. The term 'equivalent' is used to infer that the core of the processor is functionally identical, allowing the same use and optimizations of the MIPS-I Instruction Set software tool suite for compilation, software program trace, etc. This activity was started in September of 1991 under a contract from NASA-Goddard Space Flight Center (GSFC)-Flight Data Systems. The approach affected a teaming of NASA-GSFC for program development, LSI Logic for system and ASIC design coupled with the Rad-Hard process technology, and Harris (GASD) for Rad-Hard microprocessor design expertise. The program culminated with the generation of Rad-Hard Mongoose prototypes one year later.

  12. Spectroscopic evaluation of the global hardness of the atoms

    NASA Astrophysics Data System (ADS)

    Islam, Nazmul; Ghosh, Dulal C.

    2011-06-01

    This study explored a new route for calculating the global hardness of atoms using spectroscopy. Working on a new definition of global hardness and relying on the Bohr model of the hydrogenic atom, a new formula for the global hardness of atoms was derived in terms of the wave number, reflecting the electron transition from the ground state to infinity. Since the spectral lines emitted from an atom bear the signature of all complex and complicated energetic effects, including relativity, in the internal constitution of the atom, it is expected that all such effects are automatically subsumed in the hardness data computed in terms of spectral lines. The hardness of the atoms of the 103 elements of the periodic table have been computed using spectral data and in terms of the new formula suggested in this work. The effect of relativity in pre- and post-lanthanoid elements is distinctly manifest. The express periodic behaviour and correlation of the most important physico-chemical properties of elements suggest that the present approach is an alternative scientifically meaningful method for evaluating the global hardness of atoms.

  13. The thin film microwave iris

    NASA Technical Reports Server (NTRS)

    Ramey, R. L.; Landes, H. S.; Manus, E. A.

    1972-01-01

    Development of waveguide iris for microwave coupling applications using thin film techniques is discussed. Production process and installation of iris are described. Iris improves power transmission properties of waveguide window.

  14. Sealing micropores in thin castings

    NASA Technical Reports Server (NTRS)

    Mersereau, G. A.; Nitzschke, G. O.; Ochs, H. L.; Sutch, F. S.

    1981-01-01

    Microscopic pores in thin-walled aluminum castings are sealed by impregnation pretreatment. Technique was developed for investment castings used in hermetically sealed chassic for electronic circuitry. Excessively high leakage rates were previously measured in some chassis.

  15. Interference Colors in Thin Films.

    ERIC Educational Resources Information Center

    Armstrong, H. L.

    1979-01-01

    Explains interference colors in thin films as being due to the removal, or considerable reduction, of a certain color by destructive inteference that results in the complementary color being seen. (GA)

  16. Thin, Flexible IMM Solar Array

    NASA Technical Reports Server (NTRS)

    Walmsley, Nicholas

    2015-01-01

    NASA needs solar arrays that are thin, flexible, and highly efficient; package compactly for launch; and deploy into large, structurally stable high-power generators. Inverted metamorphic multijunction (IMM) solar cells can enable these arrays, but integration of this thin crystalline cell technology presents certain challenges. The Thin Hybrid Interconnected Solar Array (THINS) technology allows robust and reliable integration of IMM cells into a flexible blanket comprising standardized modules engineered for easy production. The modules support the IMM cell by using multifunctional materials for structural stability, shielding, coefficient of thermal expansion (CTE) stress relief, and integrated thermal and electrical functions. The design approach includes total encapsulation, which benefits high voltage as well as electrostatic performance.

  17. Rotating thin-shell wormhole

    NASA Astrophysics Data System (ADS)

    Ovgun, A.

    2016-11-01

    We construct a rotating thin-shell wormhole using a Myers-Perry black hole in five dimensions, using the Darmois-Israel junction conditions. The stability of the wormhole is analyzed under perturbations. We find that exotic matter is required at the throat of the wormhole to keep it stable. Our analysis shows that stability of the rotating thin-shell wormhole is possible if suitable parameter values are chosen.

  18. Center for Thin Film Studies

    DTIC Science & Technology

    1991-01-22

    techniques for reducing roughness were developed and tested . Substrate Preparation We deposited Si films by sputtering on a variety of substrates, and...deposition," Mod. Phys. Lett. B 3, 1039 (1989). 41 42 Nd: YAG LASER ABLATION OF BaTiO 3 THIN FILMS *URSULA J. GIBSON, **J.A. RUFFNER,***J.J. MCNALLY...thin films of barium titanate onto a variety of substrates, using picosecond and nanosecond pulsed Nd: YAG lasers. The films were deposited from a hot

  19. Thin EFG octagons

    NASA Astrophysics Data System (ADS)

    Kalejs, J. P.

    1994-01-01

    Mobil Solar Energy Corporation currently practices a unique crystal growth technology for producing crystalline silicon sheet, which is then cut with lasers into wafers. The wafers are processed into solar cells and incorporated into modules for photovoltaic applications. The silicon sheet is produced using a method known as Edge-defined Film-fed growth (EFG), in the form of hollow eight-sided polygons (octagons) with 10 cm faces. These are grown to lengths of 5 meters and thickness of 300 microns, with continuous melt replenishment, in compact furnaces designed to operate at a high sheet area production area of 135 sq cm/min. The present Photovoltaic Manufacturing Technology (PVMaT) three-year program seeks to advance the manufacturing line capabilities of the Mobil Solar crystal growth and cutting technologies. If successful, these advancements will provide significant reductions in already low silicon raw material usage, improve process productivity, laser cutting throughput and yield, and so lower both individual wafer cost and the cost of module production. This report summarizes the significant technical improvements in EFG technology achieved in Phase 1 of this program. Technical results are reported for each of the three main program areas: (1) thin octagon growth (crystal growth) -- to reduce the thickness of the octagon to an interim goal of 250 microns during Phase 1, with an ultimate goal of achieving 200 micron thicknesses; (2) laser cutting -- to improve the laser cutting process, so as to produce wafers with decreased laser cutting damage at increased wafer throughput rates; and (3) process control and product specification -- to implement advanced strategies in crystal growth process control and productivity designed to increase wafer yields.

  20. State of the art in hard-on-hard bearings: how did we get here and what have we achieved?

    PubMed

    Zywiel, Michael G; Sayeed, Siraj A; Johnson, Aaron J; Schmalzried, Thomas P; Mont, Michael A

    2011-03-01

    Total hip arthroplasty has shown excellent results in decreasing pain and improving function in patients with degenerative disease of the hip. Improvements in prosthetic materials, designs and implant fixation have now resulted in wear of the bearing surface being the limitation of this technology, and a number of hard-on-hard couples have been introduced to address this concern. The purpose of this article is to review the origins, development, survival rates and potential advantages and disadvantages of the following hard-on-hard bearings for total hip arthroplasty: metal-on-metal standard total hip arthroplasty; metal-on-metal hip resurfacing arthroplasty, ceramic-on-ceramic total hip arthroplasty; and ceramic-on-metal bearings. Improvements in the manufacturing of metal-on-metal bearings over the past 50 years have resulted in implants that provide low wear rates and allow for the use of large femoral heads. However, concerns remain regarding elevated serum metal ion levels, potential teratogenic effects and potentially devastating adverse local tissue reactions, whose incidence and pathogenesis remains unclear. Modern total hip resurfacing has shown excellent outcomes over 10 years in the hands of experienced surgeons. Current ceramic-on-ceramic bearings have demonstrated excellent survival with exceptionally low wear rates and virtually no local adverse effects. Concerns remain for insertional chipping, in vivo fracture and the variable incidence of squeaking. Contemporary ceramic-on-metal interfaces are in the early stages of clinical use, with little data reported to date. Hard-on-hard bearings for total hip arthroplasty have improved dramatically over the past 50 years. As bearing designs continue to improve with new and modified materials and improved manufacturing techniques, it is likely that the use of hard-on-hard bearings will continue to increase, especially in young and active patients.