Science.gov

Sample records for knoop hardness values

  1. Influence of photoactivation method and mold for restoration on the Knoop hardness of resin composite restorations.

    PubMed

    Brandt, William Cunha; Silva-Concilio, Lais Regiane; Neves, Ana Christina Claro; de Souza-Junior, Eduardo Jose Carvalho; Sinhoreti, Mario Alexandre Coelho

    2013-09-01

    The aim of this study was to evaluate in vitro the Knoop hardness in the top and bottom of composite photo activated by different methods when different mold materials were used. Z250 (3M ESPE) and XL2500 halogen unit (3M ESPE) were used. For hardness test, conical restorations were made in extracted bovine incisors (tooth mold) and also metal mold (approximately 2mm top diameter 1.5mm bottom diameter 2mm in height). Different photoactivation methods were tested: high-intensity continuous (HIC), low-intensity continuous (LIC), soft-start, or pulse-delay (PD), with constant radiant exposure. Knoop readings were performed on top and bottom restoration surfaces. Data were submitted to two-way ANOVA and Tukey's test (p?=?0.05). On the top, regardless of the mold used, no significant difference in the Knoop hardness (Knoop hardness number, in kilograms-force per square millimeter) was observed between the photoactivation methods. On the bottom surface, the photoactivation method HIC shows higher means of hardness than LIC when tooth and metal were used. Significant differences of hardness on the top and in the bottom were detected between tooth and metal. The photoactivation method LIC and the material mold can interfere in the hardness values of composite restorations. PMID:22971912

  2. Knoop Hardness - Apparent Yield Stress Relationship in Ceramics

    SciTech Connect

    Swab, Jeffrey J; LaSalvia, Jerry; Wereszczak, Andrew A; Strong, Kevin T; Danna, Dominic; Ragan, Meredith E; Ritt, Patrick J

    2012-01-01

    In Tabor's classical studies of the deformation of metals, the yield stress (Y) and hardness (H) were shown to be related according to H/Y {approx} 3 for complete or fully plastic deformation. Since then it has been anecdotally shown for ceramics that this ratio is <3. Interest exists to explore this further so Hertzian indentation was used to measure the apparent yield stress of numerous ceramics and metals and their results were compared with each material's load-dependent Knoop hardness. The evaluated ceramics included standard reference materials for hardness (silicon nitride and tungsten carbide), silicon carbide, alumina, and glass. Several steel compositions were also tested for comparison. Knoop hardness measurements at 19.6 N (i.e., toward 'complete or fully plastic deformation'), showed that 2 < H/Y < 3 for the metals and 0.8 < H/Y < 1.8 for the glasses and ceramics. Being that H/Y {ne} 3 for the ceramics indicates that Tabor's analysis is either not applicable to ceramics or that full plastic deformation is not achieved with a Knoop indentation or both.

  3. INFLUENCE OF A COBALT-CHROMIUM METAL FRAMEWORK ON SURFACE ROUGHNESS AND KNOOP HARDNESS OF VISIBLE LIGHT-POLYMERIZED ACRYLIC RESINS

    PubMed Central

    de Souza, Joane Augusto; Garcia, Renata Cunha Matheus Rodrigues; Moura, Juliana Silva; Cury, Altair Antoninha Del Bel

    2006-01-01

    Although visible light-polymerized acrylic resins have been used in removable partial dentures, it is not clear whether the presence of a metal framework could interfere with their polymerization, by possibly reflecting the light and affecting important properties, such as roughness and hardness, which would consequently increase biofilm accumulation. The aim of this study was to compare the roughness and Knoop hardness of a visible light-polymerized acrylic resin and to compare these values to those of water-bath- and microwave-polymerized resins, in the presence of a metal framework. Thirty-six specimens measuring 30.0 × 4.0 ± 0.5 mm of a microwave- (Onda Cryl), a visible light- (Triad) and a water-bath- polymerized (Clássico) (control) acrylic resins containing a cobalt-chromium metal bar were prepared. After processing, specimens were ground with 360 to 1000-grit abrasive papers in a polishing machine, followed by polishing with cloths and 1μm diamond particle suspension. Roughness was evaluated using a profilometer (Surfcorder SE 1700) and Knoop hardness (Kg/mm2) was assayed using a microhardness tester (Shimadzu HMV 2000) at distances of 50, 100, 200, 400 and 800 μm from the metal bar. Roughness and Knoop hardness means were submitted to two-way ANOVA and compared by Tukey and Kruskal Wallis tests at a 5% significance level Statistically significant differences were found (p<0.05) for roughness and Knoop hardness, with light-polymerized resin presenting the highest values (Ra = 0.11 μm and hardness between 20.2 and 21.4 Kg/mm2). Knoop values at different distances from the metal bar did not differ statistically (p>0.05). Within the limitations of this in vitro study, it was concluded that the presence of metal did not influence roughness and hardness values of any of the tested acrylic resins. PMID:19089075

  4. Effects of mouthwashes on Knoop hardness and surface roughness of dental composites after different immersion times.

    PubMed

    Miranda, Diogo de Azevedo; Bertoldo, Carlos Eduardo Dos Santos; Aguiar, Flvio Henrique Baggio; Lima, Dbora Alves Nunes Leite; Lovadino, Jos Roberto

    2011-01-01

    The aim of this in vitro study was to evaluate the effect of different mouthwashes on superficial roughness and Knoop hardness of two resin composites. Eighty specimens (6 mm and 2 mm height) were prepared and divided into eight experimental groups (n = 10) according to the resin composites (4 Seasons and Esthet X), and storage solutions (G1 - Distilled water; G2 - Colgate Plax Overnight; G3 - Colgate Plax Alcohol Free; and G4 - Colgate Plax Whitening). The initial hardness and roughness readings (T1) were measured and then the specimens were stored in 2 mL of mouthwash for 12 h (T2) and 24 h (T3). The data were analyzed with repeat-measures two-way ANOVA and Tukey's test (? = 5%). Regardless of the type of solution and time of exposure, there was no statistical difference for roughness between the resins (p = 0.44). G4 and G8 presented higher roughness means than G1, G3, G5 and G7, after 12 and 24 hours of immersion. For Knoop microhardness analysis, there was a significant reduction for all groups after 12 hours and 24 hours. We conclude that the mouthwashes containing hydrogen peroxide and/or alcohol decrease the microhardness of the resins tested; however, the mouthwash containing hydrogen peroxide had a higher deleterious effect on roughness. PMID:21537643

  5. Effect of veneering materials and curing methods on resin cement knoop hardness.

    PubMed

    Tango, Rubens Nisie; Sinhoreti, Mrio Alexandre Coelho; Correr, Amrico Bortolazzo; Correr-Sobrinho, Loureno; Consani, Rafael Leonardo Xediek

    2007-01-01

    This study evaluated the Knoop hardness of Enforce resin cement activated by the either chemical/physical or physical mode, and light cured directly and through ceramic (HeraCeram) or composite resin (Artglass). Light curing were performed with either conventional halogen light (QTH; XL2500) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. Bovine incisors had their buccal surfaces flattened and hybridized. On these surfaces a mold was seated and filled with cement. A 1.5-mm-thick disc of the veneering material was seated over this set for light curing. After storage (24 h/37 masculineC), specimens (n=10) were sectioned for hardness (KHN) measurements in a micro-hardness tester (50 gf load/ 15 s). Data were submitted to ANOVA and Tukey's test (alpha=0.05). It was observed that the dual cure mode yielded higher hardness compared to the physical mode alone, except for direct light curing with the QTH unit and through Artglass. Higher hardness was observed with QTH compared to PAC, except for Artglass/dual groups, in which similar hardness means were obtained. Low KHN means were obtained with PAC for both Artglass and HeraCeram. It may be concluded that the hardness of resin cements may be influenced by the presence of an indirect restorative material and the type of light-curing unit. PMID:18176716

  6. Evaluation of depth of cure and knoop hardness in a dental composite, photo-activated using different methods

    PubMed Central

    Hegde, Mithra N; Hegde, Priyadarshini; Malhan, Babita

    2008-01-01

    The study aimed at evaluating the depth of cure and knoop hardness of a microfine-hybrid composite resin that was photo-activated using different methods. A bipartite brass mold was filled with composite resin and photo-activation was performed using four methods: (1) Intermittent method using quartz tungsten halogen (QTH) light curing unit (LCU) (2) Continuous method (QTH) (3) Exponential method (QTH) (4) Continuous method using light-emitting diode (LED). Depth of cure was measured at the unexposed bottom surface of the specimen using microtester as a penetrometer. The surfaces exposed to light were subjected to knoop hardness testing, using a digital microhardness tester. Knoop hardness measurements were obtained at the top surface and at depths of 1, 2, 3, 4 and 5 mm. The data was analyzed using anova and Tukey's test (5%). Results showed that the depth of cure was higher with the intermittent method (QTH), followed by the continuous method (QTH), the exponential method and the continuous method (LED). At the top surface and up to 1 mm, continuous method (LED) demonstrated the highest knoop hardness number (KHN). At 2 mm and up to 5 mm, intermittent method (QTH) presented the highest KHN and continuous method (LED) showed the lowest KHN. At all depths, continuous method (QTH) showed higher KHN, as compared to the exponential method (QTH), except at 2 mm where both showed no significant difference. PMID:20142889

  7. Influence of curing tip distance on resin composite Knoop hardness number, using three different light curing units.

    PubMed

    Caldas, Danilo Biazzetto de Menezes; de Almeida, Janaina Bertoncelo; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho; Consani, Simonides

    2003-01-01

    This in vitro study evaluated the influence of curing tip distance on the Knoop Hardness Number (KHN) of a resin composite when using three different light curing units: (1) a halogen light (XL 1500 curing unit-3M), (2) a "softstart-polymerization" (Elipar Trilight curing in an exponential mode-ESPE) and (3) a PAC (Apolo 95E curing unit-DMD). The resin composite, Filtek Z250 (3M), was cured by these curing units at three light-tip distances from the resin composite: 0 mm, 6 mm and 12 mm. The resin composite specimens were flattened to their middle portion and submitted to 18 KHN measurements perspecimen. The results showed that for the Elipar Trilight unit, the hardness of the resin composite decreased as the light tip distance increased. The XL 1500 unit presented a significant decrease in hardness as the depth of cure of the resin composite increased. Apolo 95E caused a decrease in the resin composite hardness values when the depth of cure and light tip distance increased. PMID:12760705

  8. Evaluation of depth of cure and Knoop hardness in a dental composite photo-activated using different methods.

    PubMed

    Obici, Andresa Carla; Sinhoreti, Mrio Alexandre Coelho; Correr Sobrinho, Loureno; de Goes, Mario Fernando; Consani, Simonides

    2004-01-01

    The aim of this study was to evaluate the depth of cure and Knoop hardness in the P60 composite resin photo-activated using different methods. A bipartite brass matrix (3 mm in diameter X 11 mm in height) was filled with the composite and photo-activation was performed using continuous light, exponential light, intermittent light, plasma arc curing (PAC) or light-emitting diodes (LED). After opening the matrix, the uncured material was removed with a steel spatula and the polymerized composite was measured using a pachymeter. The specimens were then included in self-curing acrylic resin and worn longitudinally and the hardness was measured on the surface and at depths of 1, 2, 3, 4 and 5 mm. The data were analyzed by ANOVA and Tukey's test (5%). The results showed that the depth of cure was higher with the intermittent light, followed by continuous light, exponential light, PAC and LED methods. Up to a depth of 2 mm, all methods revealed similar hardness values, but there were differences between them at other depths, at which LED demonstrated the lowest values followed by PAC. PMID:15798823

  9. INFLUENCE OF ENERGY DENSITY OF DIFFERENT LIGHT SOURCES ON KNOOP HARDNESS OF A DUAL-CURED RESIN CEMENT

    PubMed Central

    Piva, Evandro; Correr, Loureno; Sinhoreti, Mario Alexandre Coelho; Consani, Simonides; Demarco, Flvio Fernando; Powers, John Michael

    2008-01-01

    The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm-2 (I/2x2T), 24 Jcm-2 (IxT) and 48 Jcm-2 (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (?=5%). Application of 48 J.cm-2 energy dose through the ceramic using LED (50.52.8) and HAL (50.93.7) produced significantly higher KHN means (p<0.05) than the control (44.73.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase. PMID:19089216

  10. Influence of irradiance on Knoop hardness, degree of conversion, and polymerization shrinkage of nanofilled and microhybrid composite resins.

    PubMed

    Fugolin, Ana Paula Piovezan; Correr-Sobrinho, Lourenço; Correr, Américo Bortolazzo; Sinhoreti, Mário Alexandre Coelho; Guiraldo, Ricardo Danil; Consani, Simonides

    2016-01-01

    The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microhardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P < 0.05). The microhybrid composite resin exhibited significantly greater DC and gap width than the nanofilled material (P < 0.05). Irradiance had a mostly material-dependent influence on the hardness and DC, but not the polymerization shrinkage, of composite resins. PMID:26943085

  11. Effect of different light-curing devices and aging procedures on composite knoop microhardness.

    PubMed

    Voltarelli, Fernanda Regina; dos Santos-Daroz, Claudia Batitucci; Alves, Marcelo Corra; Peris, Alessandra Rezende; Marchi, Giselle Maria

    2009-01-01

    The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC) and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S) on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s) on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness. PMID:20027457

  12. Elasticity and hardness of nano-polycrystalline boron nitrides: The apparent Hall-Petch effect

    SciTech Connect

    Nagakubo, A.; Ogi, H. Hirao, M.; Sumiya, H.

    2014-08-25

    Nano-polycrystalline boron nitride (BN) is expected to replace diamond as a superhard and superstiff material. Although its hardening was reported, its elasticity remains unclear and the as-measured hardness could be significantly different from the true value due to the elastic recovery. In this study, we measured the longitudinal-wave elastic constant of nano-polycrystalline BNs using picosecond ultrasound spectroscopy and confirmed the elastic softening for small-grain BNs. We also measured Vickers and Knoop hardness for the same specimens and clarified the relationship between hardness and stiffness. The Vickers hardness significantly increased as the grain size decreased, while the Knoop hardness remained nearly unchanged. We attribute the apparent increase in Vickers hardness to the elastic recovery and propose a model to support this insight.

  13. Elasticity and hardness of nano-polycrystalline boron nitrides: The apparent Hall-Petch effect

    NASA Astrophysics Data System (ADS)

    Nagakubo, A.; Ogi, H.; Sumiya, H.; Hirao, M.

    2014-08-01

    Nano-polycrystalline boron nitride (BN) is expected to replace diamond as a superhard and superstiff material. Although its hardening was reported, its elasticity remains unclear and the as-measured hardness could be significantly different from the true value due to the elastic recovery. In this study, we measured the longitudinal-wave elastic constant of nano-polycrystalline BNs using picosecond ultrasound spectroscopy and confirmed the elastic softening for small-grain BNs. We also measured Vickers and Knoop hardness for the same specimens and clarified the relationship between hardness and stiffness. The Vickers hardness significantly increased as the grain size decreased, while the Knoop hardness remained nearly unchanged. We attribute the apparent increase in Vickers hardness to the elastic recovery and propose a model to support this insight.

  14. Knoop microhardness mapping used to compare the efficacy of LED, QTH and PAC curing lights.

    PubMed

    Price, Richard B T; Fahey, John; Felix, Christopher M

    2010-01-01

    This study used a hardness mapping technique to compare the ability of seven curing lights to polymerize five composites. Six curing lights (Sapphire [plasma-arc: PAC], Bluephase16i [light emitting diode: LED], LEDemetron II [LED], SmartLite IQ [LED], Allegro [LED] and UltraLume-5 [Polywave LED]) were compared to an Optilux 501 (halogen: QTH) light. Five resin composites (Vit-1-escence, Tetric Evoceram, Filtek Z250, 4 Seasons and Solitaire 2) were polymerized at 4 mm and 8 mm from the end of the light guide. Four composites were light cured for the following times using these lights: Sapphire (5 seconds), Bluephase16i (5 seconds), LEDemetron II (5 seconds), SmartLite IQ (10 seconds), UltraLume-5 (10 seconds), Allegro (10 seconds) and Optilux 501 (20 seconds). Solitaire 2 required double these irradiation times. On each specimen, the Knoop microhardness (KHN) was measured at 49 locations across a 3 x 3 mm grid to determine the ability of each light to cure each brand of composite. The PAC light delivered the broadest spectrum of wavelengths, the greatest irradiance and hardness values that were 4.7 to 18.1 KHN(50gf) harder than the other lights. The ability of the lights to cure these five composites was ranked from highest to lowest: Sapphire, Optilux 501, Allegro, UltraLume-5, SmartLite IQ, LEDemetron II and Bluephase16i (ANOVA with REGWQ multiple comparison adjustment, p < 0.01). PMID:20166412

  15. The effect of annealing on the Knoop microhardness of nitrogen implanted Ti6Al4V alloy

    NASA Astrophysics Data System (ADS)

    Nath, V. C.; Sood, D. K.; Manory, R. R.

    1991-07-01

    The implantation of the Ti6Al4V alloy with nitrogen has been previously studied, and the treatment has been shown to improve the microhardness significantly [R.G. Vardiman, Defect and Diffusion Forum 57/58 (1988) 135, and references therein]. The effects of post-implantation annealing on the properties has not been studied systematically, and this is the principal aim of the RMIT work. Initial results of this study are presented and discussed. It was found that N + implantation of this alloy at 80 keV with fluences varying in the range (0.5-1.5) × 10 17ions/cm 2 caused an improvement in Knoop hardness up to 100%. Rutherford backscattering results show a buried layer containing up to 25% nitrogen in the as-implanted specimens at a depth of 130 nm. After annealing the sample implanted with 1.5 × 10 17 at 705°C, both the nitrogen concentration and the depth of the layer decrease to approximately half of their as-implanted values. The observed reduction in hardness can be attributed to the decrease in the nitrogen concentration of the buried layer, as well as to repair of the lattice. These results may indicate that only a limited amount of TiN forms directly during implantation.

  16. Hardness and damage associated with pointed indentations in armor ceramics

    NASA Astrophysics Data System (ADS)

    Swab, Jeffrey J.

    It is empirically known that an armor ceramic should be as hard as or harder than the projectile it intends to defeat. Quasi-static indentation testing is one of the most widely utilized techniques for determining the hardness of armor ceramics. Hardness measurements can also be used to generate other property values (fracture toughness, elastic properties and even the yield strength) that may be relevant to ballistic performance. While the indentation methodologies are simple and straightforward the resultant hardness values for ceramic materials can be influenced by the indenter geometry, indentation load, loading rate, specimen surface finish and ceramic microstructure. This presentation will summarize the results of a study to determine the hardness of a variety of armor-grade ceramics (Al2O3, B 4C, SiC, and WC) with different indenter geometries (Vickers and Knoop) over a range of indentation loads (0.98N to 98N) and discuss the implications for armor ceramics. The resulting data strongly indicates that the best means of determining the hardness of armor ceramics is the use of 19.6N Knoop indentations. While the hardness data and the subsequent analysis clearly support the use of the Knoop methodology to determine the hardness, it does not take into account the response of the ceramic to the indentation process. One response that is continually overlooked is the role of damage and cracking. A detailed understanding of the damage and cracking that occurs during indentation may provide valuable insights to the ballistic performance of the armor ceramics during the earliest stages of impact. To explore this material response a detailed examination of the topography of the indents and the damage and cracking that develops underneath both Knoop and Vickers indentations in a WC and SiC armor ceramic was conducted. The analysis shows that while the same types of cracks are produced in both materials the magnitude of these cracks as well as the type of damage that is produced during the indentation process is significantly different. This information is related to the ballistic performance of each material.

  17. Determination of the Mechanical Properties of Plasma-Sprayed Hydroxyapatite Coatings Using the Knoop Indentation Technique

    NASA Astrophysics Data System (ADS)

    Hasan, Md. Fahad; Wang, James; Berndt, Christopher

    2015-06-01

    The microhardness and elastic modulus of plasma-sprayed hydroxyapatite coatings were evaluated using Knoop indentation on the cross section and on the top surface. The effects of indentation angle, testing direction, measurement location and applied load on the microhardness and elastic modulus were investigated. The variability and distribution of the microhardness and elastic modulus data were statistically analysed using the Weibull modulus distribution. The results indicate that the dependence of microhardness and elastic modulus on the indentation angle exhibits a parabolic shape. Dependence of the microhardness values on the indentation angle follows Pythagoras's theorem. The microhardness, Weibull modulus of microhardness and Weibull modulus of elastic modulus reach their maximum at the central position (175 µm) on the cross section of the coatings. The Weibull modulus of microhardness revealed similar values throughout the thickness, and the Weibull modulus of elastic modulus shows higher values on the top surface compared to the cross section.

  18. Knoop microhardness and FT-Raman evaluation of composite resins: influence of opacity and photoactivation source.

    PubMed

    Albino, Luis Gustavo Barrotte; Rodrigues, José Augusto; Kawano, Yoshio; Cassoni, Alessandra

    2011-01-01

    The aim of this study was to evaluate the degree of conversion by Knoop microhardness (KHN) and FT-Raman spectroscopy (FTIR) of one nanofilled (Filtek Supreme-3M-ESPE [FS]) and one microhybrid composite (Charisma-Heraeus-Kulzer [CH]), each with different opacities, namely enamel, dentin, and translucent, which were photo-activated by a quartz-tungsten-halogen lamp (QTH) and a light-emitting diode (LED). Resin was bulk inserted into a disc-shaped mold that was 2.0 mm thick and 4 mm in diameter, obtaining 10 samples per group. KHN and FTIR values were analyzed by two-way ANOVA and Tukey's tests (α = 0.05). Nanofilled resin activated by a LED presented higher microhardness values than samples activated by a QTH for dentin opacity (p < 0.05). The microhybrid resin showed no differences in KHN or FTIR values with different activation sources or opacity. The nanofilled dentin and enamel resins showed lower FTIR values than the translucent resin. The KHN values of the translucent resins were not influenced by the light source. PMID:21670859

  19. Trace element-based food value evaluation in soft and hard shelled mud crabs.

    PubMed

    Mohapatra, Anil; Rautray, T R; Patra, Ajit K; Vijayan, V; Mohanty, Rajeeb K

    2009-11-01

    Concentrations of 10 elements were studied from the pre-moult hard shelled and newly moulted (soft shelled) crabs (Scylla serrata) by the (Energy Dispersive X-ray Fluorescence) EDXRF technique. The study evaluated the composition of all 10 elements from the body tissues and the exuvium of soft shelled and the carapace of pre-moulted hard-shelled crabs in order to evaluate the food value from nutritional and safety point of view for human consumption. The essential elements like K, Ca, Mn, Cu, etc., get reabsorbed from the carapace to the body tissues in order to meet the further requirement in the soft shelled crabs and are also utilized to some extent during the formation of new carapace, toxic element like Pb gets excreted during exuviation and element like Zn gets regulated, as and when become higher in bioavailable form. This study gives evidence that, the freshly moulted soft shelled crabs are more safe and nutritious than the hard-shelled crabs. PMID:19660512

  20. Chemical compositions and nutritional value of Asian hard clam (Meretrix lusoria) from the coast of Andaman Sea.

    PubMed

    Karnjanapratum, Supatra; Benjakul, Soottawat; Kishimura, Hideki; Tsai, Yung-Hsiang

    2013-12-15

    Chemical compositions and nutritive value of the edible portions including foot, mantle and viscera of Asian hard clam (Meretrix lusoria) harvested from the coast of Andaman Sea were determined. Proximate compositions varied with portions tested. Edible portions had moisture (76.23-84.22%) and protein (9.09-12.75%) as the major components. Carbohydrate (0.32-7.89%), fat (1.58-6.58%) and ash (1.23-2.58%) were also found at various levels, dependent upon portions. Myofibrillar proteins were observed as the major fraction in foot (40.54%) and mantle (31.65%), whilst non-protein nitrogen constituents were dominant in the viscera (36.85%). All portions contained a large amount of essential amino acids (167.66-187.63 mg/g sample), in which leucine (30.91-36.96 mg/g sample) and lysine (35.24-36.03 mg/g sample) were predominant. They were rich in polyunsaturated fatty acids (46.84-49.18% of total fatty acid) with high level of DHA (13.33-16.47 % of total fatty acids) and EPA (4.75-7.11% of total fatty acids). Cholesterol of 0.07-0.21% wet weight was detected. All portions were also rich in macro- (Na, K, Ca and Mg) and micro- (Fe, Zn, Cu and Cr) minerals. Therefore, Asian hard clam is an excellent source of several nutrients, which could be beneficial for the health of the consumers. PMID:23993597

  1. Comparison of CT-Number and Gray Scale Value of Different Dental Materials and Hard Tissues in CT and CBCT

    PubMed Central

    Emadi, Naghmeh; Safi, Yaser; Akbarzadeh Bagheban, Alireza; Asgary, Saeed

    2014-01-01

    Introduction: Computed tomography (CT) and cone-beam CT (CBCT) are valuable diagnostic aids for many clinical applications. This study was designed to compare the gray scale value (GSV) and Hounsfield unit (HU) of selected dental materials and various hard tissues using CT or CBCT. Methods and Materials: Three samples of all test materials including amalgam (AM), composite resin (CR), glass ionomer (GI), zinc-oxide eugenol (ZOE), calcium-enriched mixture (CEM) cement, AH-26 root canal sealer (AH-26), gutta-percha (GP), Coltosol (Col), Dycal (DL), mineral trioxide aggregate (MTA), zinc phosphate (ZP), and polycarbonate cement (PC) were prepared and scanned together with samples of bone, dentin and enamel using two CBCT devices, Scanora 3D (S3D) and NewTom VGi (NTV) and a spiral CT (SCT) scanner (Somatom Emotion 16 multislice spiral CT);. Subsequently, the HU and GSV values were determined and evaluated. The data were analyzed by the Kruskal-Wallis and Mann-Whitney U tests. The level of significance was determined at 0.05. Results: There were significant differences among the three different scanners (P<0.05). The differences between HU/GSV values of 12 selected dental materials using NTV was significant (P<0.05) and for S3D and SCT was insignificant (P>0.05). All tested materials showed maximum values in S3D and SCT (3094 and 3071, respectively); however, bone and dentin showed low/medium values (P<0.05). In contrast, the tested materials and tissues showed a range of values in NTV (366 to15383; P<0.05). Conclusion: Scanner system can influence the obtained HU/GSV of dental materials. NTV can discriminate various dental materials, in contrast to S3D/SCT scanners. NTV may be a more useful diagnostic aid for clinical practice. PMID:25386210

  2. Singular Values for Products of Complex Ginibre Matrices with a Source: Hard Edge Limit and Phase Transition

    NASA Astrophysics Data System (ADS)

    Forrester, Peter J.; Liu, Dang-Zheng

    2016-05-01

    The singular values squared of the random matrix product {Y = {Gr G_{r-1}} ldots G1 (G0 + A)}, where each {Gj} is a rectangular standard complex Gaussian matrix while A is non-random, are shown to be a determinantal point process with the correlation kernel given by a double contour integral. When all but finitely many eigenvalues of A* A are equal to bN, the kernel is shown to admit a well-defined hard edge scaling, in which case a critical value is established and a phase transition phenomenon is observed. More specifically, the limiting kernel in the subcritical regime of {0 < b < 1} is independent of b, and is in fact the same as that known for the case b = 0 due to Kuijlaars and Zhang. The critical regime of b = 1 allows for a double scaling limit by choosing {{b = (1 - τ/√{N})^{-1}}}, and for this the critical kernel and outlier phenomenon are established. In the simplest case r = 0, which is closely related to non-intersecting squared Bessel paths, a distribution corresponding to the finite shifted mean LUE is proven to be the scaling limit in the supercritical regime of {b > 1} with two distinct scaling rates. Similar results also hold true for the random matrix product {Tr T_{r-1} ldots T1 (G0 + A)}, with each {Tj} being a truncated unitary matrix.

  3. A Terrible Predicament: The De-Evolution of Values in Flannery O'Connor's "A Good Man Is Hard to Find."

    ERIC Educational Resources Information Center

    Tietz, Stephen; Logsdon, Loren

    2001-01-01

    Addresses problems concerning the ways Flannery O'Connor's fiction has been read. Proposes an alternate reading of "A Good Man Is Hard to Find." Suggests the primary theme of the story is the idea that each generation has the responsibility to pass on values to the next. (PM)

  4. A Case Study on Investigating the Effect of Genetic Algorithm Operators on Predicting the Global Minimum Hardness Value of Biomaterial Extrudate

    SciTech Connect

    Shankar, T.J.; Sokhansanj, Shahabaddine

    2010-02-01

    Crossover and mutation are the main search operators of genetic algorithm, one of the most important features which distinguish it from other search algorithms like simulated annealing. A genetic algorithm adopts crossover and mutation as their main genetic operators. The present work was aimed to see the effect of genetic algorithm operators like crossover and mutation (Pc & Pm), population size (n), and number of iterations (I) on predicting the minimum hardness (N) of the biomaterial extrudate. The second order polynomial regression equation developed for the extrudate property hardness in terms of the independent variables like barrel temperature, screw speed, fish content of the feed, and feed moisture content was used as the objective function in the GA analysis. A simple genetic algorithm (SGA) with a crossover and mutation operators was used in the present study. A program was developed in C language for a SGA with a rank based fitness selection method. The upper limit of population and iterations were fixed at 100. It was observed that increasing population and iterations the prediction of function minimum improved drastically. Minimum predicted hardness values were achievable with a medium population of 50, iterations of 50 and crossover and mutation probabilities of 50 % and 0.5 %. Further the Pareto charts indicated that the effect of Pc was found to be more significant when population is 50 and Pm played a major role at low population ( 10). A crossover probability of 50 % and mutation probability of 0.5 % are the threshold values for the convergence of GA to reach a global search space. A minimum predicted hardness value of 3.82 (N) was observed for n = 60 and I = 100 and Pc & Pm of 85 % and 0.5 %.

  5. Comparative evaluation of surface hardness and depth of cure of silorane and methacrylate-based posterior composite resins: An in vitro study

    PubMed Central

    Agrawal, Abhishek; Manwar, Narendra U; Hegde, Shubha G; Chandak, Manoj; Ikhar, Anuja; Patel, Aditya

    2015-01-01

    Aim: This in vitro study was carried out to compare the effect of LED light curing system on polymerization and hardness of silorane-based and methacrylate-based posterior composite resin. Materials and Methods: A total of 40 samples, 20 of silorane-based composite Filtek P-90 and 20 of methacrylate-based composite Heliomolar HB measuring 2 mm thickness and 8 mm diameter were prepared using Teflon molds and cured using LED curing light. The samples were polished and tested in Knoop hardness tester using a 50-gram load and dwell time of 15 seconds on top and bottom surfaces. The percentage depth of cure was calculated, and statistical analysis was performed using two-way ANOVA test and Student t- test. Results: Higher statistically significant values were seen for both the top and bottom surface hardness in silorane-based resins than methacrylate-based resins on LED light curing. Conclusion: Greater depth of cure was achieved in silorane-based posterior composite than in methacrylate-based posterior composite resins with a statistically significant difference. PMID:25829693

  6. Third-generation vs a second-generation LED curing light: effect on Knoop microhardness.

    PubMed

    Price, Richard B T; Felix, Corey A; Andreou, Pantelis

    2006-09-01

    Third-generation light-emitting diode (LED) curing lights use several different types of LEDs within the light to deliver a broader spectral output compared with the narrower spectral output of second-generation curing lights. This study determined the benefits of this broader spectral output. A third-generation LED curing light was modified so that the 4 peripheral LEDs, which provide the lower wavelengths, could be turned on or off, allowing the light to be used as a third- or a second-generation LED curing light. Twelve composites of A2 and lighter shades were packed into molds 2 mm deep with an internal diameter of 12 mm, and then irradiated for 20 seconds. A laboratory-grade spectroradiometer was used to ensure that all the specimens received the same irradiance and total energy (16.82 J/cm2) from the curing light in both the second- and third-generation modes. The results showed the benefits of using a broader spectrum third-generation LED curing light. This light produced composites that were as hard as when the narrower spectrum second-generation LED curing light was used (P < or = .01). In 7 of the 12 resin composites, the top surface was harder when the third-generation LED curing light was used (P < or = .01). PMID:17052038

  7. Effect of curing mode on the hardness of dual-cured composite resin core build-up materials.

    PubMed

    Arrais, César Augusto Galvão; Kasaz, Aline de Cerqueira; Albino, Luís Gustavo Barrote; Rodrigues, José Augusto; Reis, Andre Figueiredo

    2010-01-01

    This study evaluated the Knoop Hardness (KHN) values of two dual-cured composite resin core build-up materials and one resin cement exposed to different curing conditions. Two dual-cured core build-up composite resins (LuxaCore-Dual, DMG; and FluoroCore2, Dentsply Caulk), and one dual-cured resin cement (Rely X ARC, 3M ESPE) were used in the present study. The composite materials were placed into a cylindrical matrix (2 mm in height and 3 mm in diameter), and the specimens thus produced were either light-activated for 40 s (Optilux 501, Demetron Kerr) or were allowed to self-cure for 10 min in the dark (n = 5). All specimens were then stored in humidity at 37 degrees C for 24 h in the dark and were subjected to KHN analysis. The results were submitted to 2-way ANOVA and Tukey's post-hoc test at a pre-set alpha of 5%. All the light-activated groups exhibited higher KHN values than the self-cured ones (p = 0.00001), regardless of product. Among the self-cured groups, both composite resin core build-up materials showed higher KHN values than the dual-cured resin cement (p = 0.00001). LuxaCore-Dual exhibited higher KHN values than FluoroCore2 (p = 0.00001) when they were allowed to self-cure, while no significant differences in KHN values were observed among the light-activated products. The results suggest that dual-cured composite resin core build-up materials may be more reliable than dual-cured resin cements when curing light is not available. PMID:20658046

  8. Ormosils of high hardness

    SciTech Connect

    Iwamoto, Takashi; Mackenzie, J.D.

    1994-12-31

    Organically modified silicates (ormosils) of high hardness were prepared by the reactions of tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS) aided by ultrasonic irradiation. The mechanisms leading to the hard ormosil formation were investigated by liquid state {sup 29}Si NMR spectroscopy. PDMS chains were found to be broken into shorter chains and/or 4-membered siloxane rings during the reaction and finally, all PDMS chains were chemically incorporated as short chains into silica networks. Vickers hardnesses of the hard ormosils were measured and compared with those of the hardest transparent plastics. Whereas the hardest transparent plastics have Vickers hardness values of less than 25 kg/mm{sup 2}, the hard ormosils have Vickers hardnesses tip to higher than 150 kg/mm{sup 2}. A theoretical model was developed for the calculation of Vickers hardnesses of the hard ormosils and agreed well with experimental results. Predictions based on this theory indicate that even harder ormosils can be made when Al{sub 2}O{sub 3}, ZrO{sub 2} and TiO{sub 2} are substituted for SiO{sub 2}. Results based on these new ormosils are also presented.

  9. Microindentation hardness evaluation of iridium alloy clad vent set cups

    SciTech Connect

    Ulrich, G.B.; DeRoos, L.F.; Stinnette, S.E.

    1992-05-15

    An iridium alloy, DOP-26, is used as cladding for {sup 238}PuO{sup 2} fuel in radioisotope heat sources for space power systems. Presently, DOP-26 iridium alloy clad vent sets (CVS) are being manufactured at the Oak Ridge Y-12 Plant for potential use in the National Aeronautics and Space Administration's Cassini mission to Saturn. Wrought/ground/stress relieved blanks are warm formed into CVS cups. These cups are then annealed to recrystallize the material for subsequent fabrication/assembly operations as well as for final use. One of the cup manufacturing certification requirements is to test for Vickers microindentation hardness. New microindentation hardness specification limits, 210 to 310 HV, have been established for a test load of 1000 grams-force (gf). The original specification limits, 250 to 350 HV, were for 200 gf testing. The primary reason for switching to a higher test load was to reduce variability in the test data. The DOP-26 alloy exhibits microindentation hardness load dependence, therefore, new limits were needed for 1000 gf testing. The new limits were established by testing material from 15 CVS cups using 200 gf and 1000 gf loads and then statistically analyzing the data. Additional work using a Knoop indenter and a 10 gf load indicated that the DOP-26 alloy grain boundaries have higher hardnesses than the grain interiors.

  10. Microindentation hardness evaluation of iridium alloy clad vent set cups

    SciTech Connect

    Ulrich, G.B.; DeRoos, L.F.; Stinnette, S.E.

    1992-05-15

    An iridium alloy, DOP-26, is used as cladding for {sup 238}PuO{sup 2} fuel in radioisotope heat sources for space power systems. Presently, DOP-26 iridium alloy clad vent sets (CVS) are being manufactured at the Oak Ridge Y-12 Plant for potential use in the National Aeronautics and Space Administration`s Cassini mission to Saturn. Wrought/ground/stress relieved blanks are warm formed into CVS cups. These cups are then annealed to recrystallize the material for subsequent fabrication/assembly operations as well as for final use. One of the cup manufacturing certification requirements is to test for Vickers microindentation hardness. New microindentation hardness specification limits, 210 to 310 HV, have been established for a test load of 1000 grams-force (gf). The original specification limits, 250 to 350 HV, were for 200 gf testing. The primary reason for switching to a higher test load was to reduce variability in the test data. The DOP-26 alloy exhibits microindentation hardness load dependence, therefore, new limits were needed for 1000 gf testing. The new limits were established by testing material from 15 CVS cups using 200 gf and 1000 gf loads and then statistically analyzing the data. Additional work using a Knoop indenter and a 10 gf load indicated that the DOP-26 alloy grain boundaries have higher hardnesses than the grain interiors.

  11. Effect of Polymerization Cycles on Gloss, Roughness, Hardness and Impact Strength of Acrylic Resins.

    PubMed

    Consani, Rafael Leonardo Xediek; Folli, Bianca L; Nogueira, Moises C F; Correr, Americo Bortolazzo; Mesquita, Marcelo F

    2016-04-01

    The aim of this study was to evaluate the conventional and boiled polymerization cycles on gloss, roughness, hardness and impact strength of acrylic resins. Samples were made for each Classico and QC-20 materials (n=10) in dental stone molds obtained from rectangular metallic matrices embedded in metallic flasks. The powder-liquid ratio and manipulation of the acrylic resins' were accomplished according to manufacturers' instructions and the resins were conventionally packed in metallic flasks. After polymerization by (1) conventional: 74 °C for 9 h (Classico) and (2) boiled: 20 min (QC-20) cycles, the samples were deflasked after cooling at room temperature and conventionally finished and polished. The properties were evaluated after storage in water at 37 °C for 24 h. Gloss was verified with Multi Gloss 268 meter (Konica Minolta), surface roughness was measured with Surfcorder SE 1700 rugosimeter (Kosaka), Knoop hardness number was obtained with HMV-200 microdurometer, and impact strength was measured in an Otto Wolpert-Werke device by Charpy system (40 kpcm). Data were subjected to Student's t-test (at α=0.05). The results were: Gloss: 67.7 and 62.2 for Classico and QC-20 resins, respectively; Surface roughness: 0.874 and 1.469 Ra-µm for Classico and QC-20, respectively; Knoop hardness: 27.4 and 26.9 for Classico and QC-20, respectively; and Impact strength: 37.6 and 33.6 kgf/cm2 for Classico and QC-20, respectively. No statistically significant difference (p>0.05)were found between the resins for the evaluated properties. In conclusion, conventional and boiled polymerization cycles had similar effects on gloss, roughness, hardness and impact strength of both Classico and QC-20 resins. PMID:27058380

  12. SUPER HARD SURFACED POLYMERS

    SciTech Connect

    Mansur, Louis K; Bhattacharya, R; Blau, Peter Julian; Clemons, Art; Eberle, Cliff; Evans, H B; Janke, Christopher James; Jolly, Brian C; Lee, E H; Leonard, Keith J; Trejo, Rosa M; Rivard, John D

    2010-01-01

    High energy ion beam surface treatments were applied to a selected group of polymers. Of the six materials in the present study, four were thermoplastics (polycarbonate, polyethylene, polyethylene terephthalate, and polystyrene) and two were thermosets (epoxy and polyimide). The particular epoxy evaluated in this work is one of the resins used in formulating fiber reinforced composites for military helicopter blades. Measures of mechanical properties of the near surface regions were obtained by nanoindentation hardness and pin on disk wear. Attempts were also made to measure erosion resistance by particle impact. All materials were hardness tested. Pristine materials were very soft, having values in the range of approximately 0.1 to 0.5 GPa. Ion beam treatment increased hardness by up to 50 times compared to untreated materials. For reference, all materials were hardened to values higher than those typical of stainless steels. Wear tests were carried out on three of the materials, PET, PI and epoxy. On the ion beam treated epoxy no wear could be detected, whereas the untreated material showed significant wear.

  13. 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. PMID:16253265

  14. Wear of hard materials by hard particles

    SciTech Connect

    Hawk, Jeffrey A.

    2003-10-01

    Hard materials, such as WC-Co, boron carbide, titanium diboride and composite carbide made up of Mo2C and WC, have been tested in abrasion and erosion conditions. These hard materials showed negligible wear in abrasion against SiC particles and erosion using Al2O3 particles. The WC-Co materials have the highest wear rate of these hard materials and a very different material removal mechanism. Wear mechanisms for these materials were different for each material with the overall wear rate controlled by binder composition and content and material grain size.

  15. Hard metal composition

    SciTech Connect

    Sheinberg, H.

    1986-12-02

    This patent describes a hard composition of matter having a Rockwell A hardness value of at least approximately 85, comprising the compressed and densified reaction product of: a minor amount of a boron carbide component selected from the group consisting of (a) boron carbide and (b) boron and carbon, the boron and carbon being present in amounts sufficient to form boron carbide in situ, wherein the boron carbide component consists essentially of B/sub 4/C; a major amount of a metal mixture consisting essentially of: (a) a first metal component selected from the group consisting of tungsten and molybdenum and mixtures thereof, and (b) a second metal component selected from the group consisting of nickel and iron and mixtures thereof; wherein the minor amount of the boron carbide component is between 3% and 6% by weight of the composition of matter when the first metal component is tungsten. The minor amount of the boron carbide component is between 6% and 10% by weight of the composition when the first metal component is molybdenum. The boron carbide component is between 3% and 10% when the first metal component is a mixture of tungsten and molybdenum, with the remainder of the composition being formed of the metal mixture, and wherein the first metal component is from 70% to less than about 90% by weight of the metal mixture when the first metal component is tungsten, and wherein the first metal component is from 72% to less than about 90% by weight of the metal mixture when the first metal component is molybdenum.

  16. "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

  17. "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…

  18. Hardness of group IVA and IVB nitrides

    NASA Astrophysics Data System (ADS)

    Li, Keyan; Xue, Dongfeng

    2010-05-01

    The hardnesses of various phases of group IVA and IVB nitrides (M3N4, M=C, Si, Ge, Sn, Ti, Zr or Hf; MN, M=Ti, Zr or Hf) were calculated using the bond electronegativity model for material hardness. The hardnesses of group IV nitrides increase with an increase in their average coordination numbers except for carbon nitrides, for which increasing the average coordination numbers results in a reduction in hardness. We suggest that for light-element compounds, the diamond-like structure represents the hardest one among all possible structures, whereas a high coordination number is generally required for heavy-element compounds to achieve high hardness values. This work provides a useful guide for designing novel nitride materials having excellent mechanical performances.

  19. Hard copy output technologies

    SciTech Connect

    Herzog, D.G.

    1987-01-01

    This book contains the proceedings from the January 13-14, 1987 conference sponsored by SPIE - The International Society for Optical Engineering. The four sessions covered the following topics: Electronic Printing and Hard Copy Output Technologies; Recording and Printing Media; Hard Copy Output Technologies - Business Graphics; and High Resolution Printing and Recording Systems. Eighteen papers are presented in this volume.

  20. 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.

  1. 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.

  2. The hard metal diseases

    SciTech Connect

    Cugell, D.W. )

    1992-06-01

    Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure.66 references.

  3. 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)

  4. Hardness methods for testing maize kernels.

    PubMed

    Fox, Glen; Manley, Marena

    2009-07-01

    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 hardness. Genotypes and growing environment influence the final protein and starch content and, to a lesser extent, composition. However, hardness is a highly heritable trait and, hence, when a desirable level of hardness is finally agreed upon, the breeders will quickly be able to produce material with the hardness levels required by the industry. PMID:19496585

  5. Effects of preheating and precooling on the hardness and shrinkage of a composite resin cured with QTH and LED.

    PubMed

    Osternack, F H; Caldas, D B M; Almeida, J B; Souza, E M; Mazur, R F

    2013-01-01

    The aim of this study was to evaluate in vitro the hardness and shrinkage of a pre-cooled or preheated hybrid composite resin cured by a quartz-tungsten-halogen light (QTH) and light-emitting diode (LED) curing units. The temperature on the tip of the devices was also investigated. Specimens of Charisma resin composite were produced with a metal mold kept under 37°C. The syringes were submitted to 4°C, 23°C, and 60°C (n=20) before light-curing, which was carried out with the Optilux 501 VCL and Elipar FreeLight 2 units for 20 seconds. The specimens were kept under 37°C in a high humidity condition and darkness for 48 hours. The Knoop hardness test was carried out with a 50 gram-force (gf) load for 10 seconds, and the measurement of the shrinkage gap was carried out using an optical microscope. The data were subjected to analysis of variance and the Games-Howell test (α=0.05). The mean hardness of the groups were similar, irrespective of the temperatures (p>0.05). For 4°C and 60°C, the top surface light-cured by LED presented significantly reduced shrinkage when compared with the bottom and to both surfaces cured by QTH (p<0.05). It was concluded that the hardness was not affected by pre-cooling or preheating. However, polymerization shrinkage was slightly affected by different pre-polymerization temperatures. The QTH-curing generated greater shrinkage than LED-curing only when the composite was preheated. Different temperatures did not affect the composite hardness and shrinkage when cured by a LED curing unit. PMID:23088189

  6. 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.

  7. Al-Mn coating electrodeposited from ionic liquid on NdFeB magnet with high hardness and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Ding, Jingjing; Xu, Bajin; Ling, Guoping

    2014-06-01

    Al-Mn coatings were electrodeposited on sintered NdFeB permanent magnet in MnCl2-AlCl3-1-ethyl-3-methylim-idazolium chloride (MnCl2-AlCl3-EMIC) ionic liquid at room temperature. The coatings were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The adhesion strength of the coating on NdFeB substrate was evaluated by thermal shock and scratch test. The hardness and corrosion behavior of Al-Mn coating were measured by a Knoop microhardness tester, immersion test and neutral salt spray test respectively. The results showed that the amorphous structure of the deposits was obtained at the current density of 6 mA/cm2, while higher current densities resulted in a mixed structure of amorphous and crystalline. The Al-Mn coating showed excellent adhesion strength on NdFeB substrate with the thermal shock test over 30 cycles and Lc > 80 N. The hardness of Al-Mn coating was up to 5.4 GPa. The amorphous Al-Mn coating showed an anodic sacrificial protection with a low corrosion rate for NdFeB. Meanwhile, the magnetic properties measured by an AMT-4 magnetic measurement device showed that Al-Mn coating did not deteriorate the magnetic property of NdFeB.

  8. The Dubious Value of Value Neutrality

    ERIC Educational Resources Information Center

    Balch, Stephen H.

    2006-01-01

    Hard science is properly value neutral. But when that ideological neutrality extends to the whole university, the traditional foundation crumbles. Steve Balch laments the moral vacuum that now substitutes for fundamental principles, because it is impossible to frame a program of education--especially in the humanities and social sciences--without…

  9. The Dubious Value of Value Neutrality

    ERIC Educational Resources Information Center

    Balch, Stephen H.

    2006-01-01

    Hard science is properly value neutral. But when that ideological neutrality extends to the whole university, the traditional foundation crumbles. Steve Balch laments the moral vacuum that now substitutes for fundamental principles, because it is impossible to frame a program of education--especially in the humanities and social sciences--without

  10. Hard superconducting nitrides

    PubMed Central

    Chen, Xiao-Jia; Struzhkin, Viktor V.; Wu, Zhigang; Somayazulu, Maddury; Qian, Jiang; Kung, Simon; Christensen, Axel Nørlund; Zhao, Yusheng; Cohen, Ronald E.; Mao, Ho-kwang; Hemley, Russell J.

    2005-01-01

    Detailed study of the equation of state, elasticity, and hardness of selected superconducting transition-metal nitrides reveals interesting correlations among their physical properties. Both the bulk modulus and Vickers hardness are found to decrease with increasing zero-pressure volume in NbN, HfN, and ZrN. The computed elastic constants from first principles satisfy c11 > c12 > c44 for NbN, but c11 > c44 > c12 for HfN and ZrN, which are in good agreement with the neutron scattering data. The cubic δ-NbN superconducting phase possesses a bulk modulus of 348 GPa, comparable to that of cubic boron nitride, and a Vickers hardness of 20 GPa, which is close to sapphire. Theoretical calculations for NbN show that all elastic moduli increase monotonically with increasing pressure. These results suggest technological applications of such materials in extreme environments. PMID:15728352

  11. 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.

  12. 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.…

  13. 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,…

  14. 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,

  15. 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)

  16. Work Hard. Be Nice

    ERIC Educational Resources Information Center

    Mathews, Jay

    2009-01-01

    In 1994, fresh from a two-year stint with Teach for America, Mike Feinberg and Dave Levin inaugurated the Knowledge Is Power Program (KIPP) in Houston with an enrollment of 49 5th graders. By this Fall, 75 KIPP schools will be up and running, setting children from poor and minority families on a path to college through a combination of hard work,…

  17. Hard Times Hit Schools

    ERIC Educational Resources Information Center

    McNeil, Michele

    2008-01-01

    Hard-to-grasp dollar amounts are forcing real cuts in K-12 education at a time when the cost of fueling buses and providing school lunches is increasing and the demands of the federal No Child Left Behind Act still loom larger over states and districts. "One of the real challenges is to continue progress in light of the economy," said Gale Gaines,…

  18. 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.

  19. 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.

  20. Benchmarking for maximum value.

    PubMed

    Baldwin, Ed

    2009-03-01

    Speaking at the most recent Healthcare Estates conference, Ed Baldwin, of international built asset consultancy EC Harris LLP, examined the role of benchmarking and market-testing--two of the key methods used to evaluate the quality and cost-effectiveness of hard and soft FM services provided under PFI healthcare schemes to ensure they are offering maximum value for money. PMID:19344004

  1. 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.

  2. 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.

  3. 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

  4. Spins, phonons, and hardness

    SciTech Connect

    Gilman, J.J.

    1996-12-31

    In crystals (and/or glasses) with localized sp{sup 3} or spd-bonding orbitals, dislocations have very low mobilities, making the crystals very hard. Classical Peierls-Nabarro theory does not account for the low mobility. The breaking of spin-pair bonds which creates internal free-radicals must be considered. Therefore, a theory based on quantum mechanics has been proposed (Science, 261, 1436 (1993)). It has been applied successfully to diamond, Si, Ge, SiC, and with a modification to TiC and WC. It has recently been extended to account for the temperature independence of the hardness of silicon at low temperatures together with strong softening at temperatures above the Debye temperature. It is quantitatively consistent with the behaviors of the Group 4 elements (C, Si, Ge, Sn) when their Debye temperatures are used as normalizing factors; and appears to be consistent with data for TiC if an Einstein temperature for carbon is used. Since the Debye temperature marks the approximate point at which phonons of atomic wavelengths become excited (as contrasted with collective acoustic waves), this confirms the idea that the process which limits dislocation mobility is localized to atomic dimensions (sharp kinks).

  5. What Value "Value Added"?

    ERIC Educational Resources Information Center

    Richards, Andrew

    2015-01-01

    Two quantitative measures of school performance are currently used, the average points score (APS) at Key Stage 2 and value-added (VA), which measures the rate of academic improvement between Key Stage 1 and 2. These figures are used by parents and the Office for Standards in Education to make judgements and comparisons. However, simple…

  6. Decreased ventilatory function in hard metal workers.

    PubMed Central

    Kusaka, Y; Iki, M; Kumagai, S; Goto, S

    1996-01-01

    OBJECTIVES: To study individual effects on pulmonary function of exposure to hard metal including cobalt. METHODS: All of the workers in a hard metal company (583 men and 120 women) were examined for smoking, respiratory symptoms, ventilatory function, occupational history of exposure to hard metal, and present exposure to airborne cobalt. The ventilatory function indices (forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory volume in one second per cent (FEV1%), peak expiratory flow (PEF), mid-maximal flow (MMF), forced expiratory flow at 50% vital capacity (V50), forced expiratory flow at 25% vital capacity (V25)) were standardised for height and age and expressed as a percentage of predicted values. RESULTS: Two way analysis of variance of indices of ventilatory function showed that an interaction of hard metal exposure and smoking decreased %V50 for both men and women. Among the currently exposed men, those with asthmatic symptoms (defined as reversible dispnoea with wheeze) had significantly lower %FVC, %FEV1%, %PEF, %MMF, %V50, and %V25 than did workers without asthma. The ventilatory disfunction did not differ between exposed and non-exposed workers with asthmatic symptoms. Even among the men without asthmatic symptoms, %V50 was significantly lowered by the interaction of hard metal exposure and smoking. The multilinear regression analysis of indices of ventilatory function for all of the subjects on sex, smoking (Brinkman index), exposure to hard metal, and asthmatic symptoms showed that asthmatic symptoms and smoking had significant effects on all variables and that the decrease in %V25 was associated with hard metal exposure. In the currently exposed and non-exposed workers, multilinear regression analysis applying indices for cobalt exposure (mean cobalt concentration, duration of exposure, and cumulative dose) showed that not only asthmatic symptoms or smoking but also duration of exposure had significant decreasing effects on %FVC, %MMF, and %V25. CONCLUSIONS: Occupational exposure to hard metal probably causes impairment of ventilatory function in a dose dependent manner. PMID:8704861

  7. 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.

  8. 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.

  9. 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.

  10. 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…

  11. MISTIC: Radiation hard ECRIS

    NASA Astrophysics Data System (ADS)

    Labrecque, F.; Lecesne, N.; Bricault, P.

    2008-10-01

    The ISAC RIB facility at TRIUMF utilizes up to 100 μA from the 500 MeV H- cyclotron to produce RIB using the isotopic separation on line (ISOL) method. In the moment, we are mainly using a hot surface ion source and a laser ion source to produce our RIB. A FEBIAD ion source has been recently tested at ISAC, but these ion sources are not suitable for gaseous elements like N, O, F, Ne, … , A new type of ion source is then necessary. By combining a high frequency electromagnetic wave and a magnetic confinement, the ECRIS [R. Geller, Electron Cyclotron Resonance Ion Source and ECR Plasmas, Institute of Physics Publishing, Bristol, 1996], [1] (electron cyclotron resonance ion source) can produce high energy electrons essential for efficient ionization of those elements. To this end, a prototype ECRIS called MISTIC (monocharged ion source for TRIUMF and ISAC complex) has been built at TRIUMF using a design similar to the one developed at GANIL [GANIL (Grand Accélérateur National d'Ions Lourds), www.ganil.fr], [2] The high level radiation caused by the proximity to the target prevented us to use a conventional ECRIS. To achieve a radiation hard ion source, we used coils instead of permanent magnets to produce the magnetic confinement. Each coil is supplied by 1000 A-15 V power supply. The RF generator cover a frequency range from 2 to 8 GHz giving us all the versatility we need to characterize the ionization of the following elements: He, Ne, Ar, Kr, Xe, C, O, N, F. Isotopes of these elements are involved in star thermonuclear cycles and, consequently, very important for researches in nuclear astrophysics. Measures of efficiency, emittance and ionization time will be performed for each of those elements. Preliminary tests show that MISTIC is very stable over a large range of frequency, magnetic field and pressure.

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. Effect of coatings on hardness of commercial marbles

    NASA Astrophysics Data System (ADS)

    Zedef, Veysel

    2016-04-01

    In this study, three type of marble and one granite were chosen to understand if the coating is effective on hardness of the commercial rocks. To understand the hardness of the rock, Schmidt hammer tests were undertaken. The used device allowed us uniaxial compressive strength (UCS) as well as Schmidt rebound (R). The coated samples have clearly high R and UCS values when compared to uncoated samples. The Elazig visne, the well-known marble of Turkey, have 35.6 R and 44.2 MPa UCS values of coated samples. On the other hand, uncoated surface of the same marble have 30.5 R and 35.4 MPa UCS.

  17. Hardness enhancement and crosslinking mechanisms in polystyrene irradiated with high energy ion-beams

    SciTech Connect

    Lee, E.H.; Rao, G.R.; Mansur, L.K.

    1996-12-31

    Surface hardness values several times larger than steel were produced using high energy ion beams at several hundred keV to MeV. High LET is important for crosslinking. Crosslinking is studied by analyzing hardness variations in response to irradiation parameter such as ion species, energy, and fluence. Effective crosslinking radii at hardness saturation are derived base on experimental data for 350 keV H{sup +} and 1 MeV Ar{sup +} irradiation of polystyrene. Saturation value for surface hardness is about 20 GPa.

  18. Value, Value, Where Is the Value?

    ERIC Educational Resources Information Center

    Kaufman, Roger

    2003-01-01

    Discusses measurement in performance improvement, including the Kirkpatrick four-level model of evaluation for training, and adding value. Highlights include adding value at all levels of organizational performance, for the clients and society; other models of performance improvement; the major focus of HPT (human performance technology); and…

  19. Hard-on-Hard Total Hip Impingement Causes Extreme Contact Stress Concentrations

    PubMed Central

    Elkins, Jacob M.; O’Brien, Megan K.; Stroud, Nicholas J.; Pedersen, Douglas R.; Callaghan, John J.

    2010-01-01

    Background Impingement events, in addition to their role immediately proximate to frank dislocation, hold the potential to damage new-generation hard-on-hard bearings as a result of the relatively unforgiving nature of the materials and designs. Because of the higher stiffness and tighter design tolerances of metal-on-metal and ceramic implants, surgical positioning plausibly has become even more important. Questions/purposes We asked (1) whether, and under what cup orientation conditions, hard-on-hard impingements might challenge implant material failure strength; and (2) whether particle generation propensity at impingement and egress sites would show similar dependence on cup orientation. Methods Realistic computational simulations were enabled by multistage finite element analyses, addressing both global construct motion and loading, and focal stress concentrations at neck impingement and rim egress sites. The global model, validated by a cadaveric simulation in a servohydraulic hip simulator, included both hardware components and advanced anisotropic capsule characterization. Parametric computational runs explored the effect of cup orientation for both ceramic-on-ceramic and metal-on-metal bearing couples for two distinct motion sequences associated with dislocation. Results Stress concentrations from impingement increased nearly linearly with increased cup tilt and with cup anteversion. In some situations, peak values of stress approached or exceeded 1 GPa, levels challenging the yield strength of cobalt-chromium implants, and potentially the fracture strength of ceramics. The tendency for impingement events to generate debris, indexed in terms of a new scraping severity metric, showed orientation dependences similar to that for bulk material failure. Conclusions Damage propensity arising from impingement events in hard total hip bearings is highly orientation-dependent. PMID:20953853

  20. 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.}

  1. Evaluation of mechanical properties of some glycine complexes

    NASA Astrophysics Data System (ADS)

    Nagaraju, D.; Raja Shekar, P. V.; Chandra, Ch. Sateesh; Rao, K. Kishan; Krishna, N. Gopi

    2014-04-01

    The variation of Vickers hardness with load for (101) glycine zinc chloride (GZC), (001) glycine lithium sulphate (GLS), (001) triglycine sulphate (TGS) and (010) glycine phosphite (GPI) crystals was studied. From the cracks initiated along the corners of the indentation impression, crack lengths were measured and the fracture toughness value and brittle index number were determined. The hardness related parameters viz. yield strength and Young's modulus were also estimated. The anisotropic nature of the crystals was studied using Knoop indentation technique.

  2. Evaluation of mechanical properties of some glycine complexes

    SciTech Connect

    Nagaraju, D.; Raja Shekar, P. V.; Chandra, Ch. Sateesh; Rao, K. Kishan; Krishna, N. Gopi

    2014-04-24

    The variation of Vickers hardness with load for (101) glycine zinc chloride (GZC), (001) glycine lithium sulphate (GLS), (001) triglycine sulphate (TGS) and (010) glycine phosphite (GPI) crystals was studied. From the cracks initiated along the corners of the indentation impression, crack lengths were measured and the fracture toughness value and brittle index number were determined. The hardness related parameters viz. yield strength and Young’s modulus were also estimated. The anisotropic nature of the crystals was studied using Knoop indentation technique.

  3. Hard processes in quantum chromodynamics

    NASA Astrophysics Data System (ADS)

    Dokshitzer, Yu. L.; Dyakonov, D. I.; Troyan, S. I.

    1980-02-01

    The use of Quantum Chromodynamics (QCD) in treating the hadronic world has become an overwhelming trend in particle physics. Owing to the asymptotic freedom of QCD, one can use perturbative methods to describe hard hadronic processes, i.e. those in which small distances as compared to hadron size are important. This paper is devoted to an improved perturbative QCD analysis of a wide class of hard processes. We start with the deep inelastic lepton-hadron scattering and the inclusive e +e - annihilation to hadrons, and show how and to what extent QCD imitates the parton model. We move further to hard semi-inclusive processes, and demonstrate that in this case the QCD predictions differ drastically from those of the parton model. The approach outlined in the paper paves the way for a detailed quantitative description of hard processes (provided QCD is the right theory). Special attention is given to the underlying physics. In particular, a possible influence of the hitherto unknown confinement mechanism on perturbative QCD analysis is discussed.

  4. 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…

  5. Hard sphere packings within cylinders.

    PubMed

    Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick

    2016-02-23

    Arrangements of identical hard spheres confined to a cylinder with hard walls have been used to model experimental systems, such as fullerenes in nanotubes and colloidal wire assembly. Finding the densest configurations, called close packings, of hard spheres of diameter σ in a cylinder of diameter D is a purely geometric problem that grows increasingly complex as D/σ increases, and little is thus known about the regime for D > 2.873σ. In this work, we extend the identification of close packings up to D = 4.00σ by adapting Torquato-Jiao's adaptive-shrinking-cell formulation and sequential-linear-programming (SLP) technique. We identify 17 new structures, almost all of them chiral. Beyond D ≈ 2.85σ, most of the structures consist of an outer shell and an inner core that compete for being close packed. In some cases, the shell adopts its own maximum density configuration, and the stacking of core spheres within it is quasiperiodic. In other cases, an interplay between the two components is observed, which may result in simple periodic structures. In yet other cases, the very distinction between the core and shell vanishes, resulting in more exotic packing geometries, including some that are three-dimensional extensions of structures obtained from packing hard disks in a circle. PMID:26843132

  6. A finger-like hardness tester based on the contact electromechanical impedance of a piezoelectric bimorph cantilever.

    PubMed

    Fu, Ji; Li, Faxin

    2015-10-01

    We proposed a finger-like hardness tester based on the electromechanical impedance of a piezoelectric bimorph cantilever. A Vickers indenter was fabricated to the free end of the bimorph to contact the sample. The contact force was monitored by a strain gauge and the contact area was obtained by tracking the bimorph's resonance frequency. The bimorph-sample contact system was modeled by the electromechanical equivalent circuit method. Verification experiments on standard hardness samples were conducted and the measured hardness values agreed well with those given by a conventional Vickers hardness tester. Further hardness measurement on a gear wheel showed that the proposed hardness tester is very adaptive and can be used for inner surface testing or in situ testing, where other hardness testers may not be applicable. The proposed hardness tester can be regarded as an improved ultrasonic hardness tester. PMID:26520966

  7. A finger-like hardness tester based on the contact electromechanical impedance of a piezoelectric bimorph cantilever

    NASA Astrophysics Data System (ADS)

    Fu, Ji; Li, Faxin

    2015-10-01

    We proposed a finger-like hardness tester based on the electromechanical impedance of a piezoelectric bimorph cantilever. A Vickers indenter was fabricated to the free end of the bimorph to contact the sample. The contact force was monitored by a strain gauge and the contact area was obtained by tracking the bimorph's resonance frequency. The bimorph-sample contact system was modeled by the electromechanical equivalent circuit method. Verification experiments on standard hardness samples were conducted and the measured hardness values agreed well with those given by a conventional Vickers hardness tester. Further hardness measurement on a gear wheel showed that the proposed hardness tester is very adaptive and can be used for inner surface testing or in situ testing, where other hardness testers may not be applicable. The proposed hardness tester can be regarded as an improved ultrasonic hardness tester.

  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. Effect of hydrogen on hardness of amorphous silicon

    NASA Astrophysics Data System (ADS)

    Danesh, P.; Pantchev, B.; Wiezorek, J.; Schmidt, B.; Grambole, D.

    2011-01-01

    A comparative study of hardness of thin films of hydrogenated amorphous silicon (a-Si:H) and hydrogen-free amorphous silicon (a-Si) was carried out to reveal the role of hydrogen in the plastic properties of amorphous silicon. In addition, the effect of hydrogen on hardness was established by changing hydrogen concentration in the material using post-deposition processing of the samples. The hydrogen concentration in a-Si:H was decreased by thermal annealing. In a-Si hydrogen was introduced by plasma hydrogenation. The values of hardness of the as-prepared a-Si and a-Si:H films were determined by nanoindentation using depth profiling. Low-depth indentation was applied to evaluate the effect of post-hydrogenation. The results obtained show that the presence of hydrogen in the amorphous silicon network leads to the increase in hardness. The conducted experiments demonstrate that plasma hydrogenation can be used as an effective tool to increase the hardness of amorphous silicon. Hardness of a-Si:H of about 12.3-12.7 GPa is as high as of crystalline silicon, suggesting a-Si:H can be a substitute for crystalline silicon in some MEMS.

  10. Quantum quench with hard wall boundary conditions

    NASA Astrophysics Data System (ADS)

    Goldstein, Garry; Andrei, Natan

    2015-03-01

    In this work we present analysis of a quench for the Lieb Liniger gas contained in a large box with hard wall boundary conditions. We study the time average of local correlation functions. We show that both the quench action logic and the GGE are applicable. We show that the time average of the system corresponds to an eigenstate of the Lieb Liniger Hamiltonian. We show that this eigenstate is related to an eigenstate of a Lieb Liniger Hamiltonian with periodic boundary conditions on an interval of twice the length and with twice as many particles (a doubled system). We further show that local operators with support far away from the boundaries of the hard wall Lieb Liniger gas have the same expectation values as corresponding operators for the doubled system. We present an example of a quench where the Lieb Liniger gas is initially confined in several traps and then released into a bigger container, an approximate description of the Newton cradle experiment. This research was supported by NSF Grant DMR 1006684 and Rutgers CMT fellowship.

  11. 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.

  12. Weld cladding of hard surfaces

    NASA Astrophysics Data System (ADS)

    Habrekke, T.

    1993-02-01

    A literature study about clad welding of hard surfaces on steel is performed. The purpose was to see what kind of methods are mainly used, and particular attention is paid to clad welding of rolls. The main impression from this study is that several methods are in use. Some of these must be considered as 'too exotic' for the aim of the program, such as laser build-up welding. However, clad welding of hard surfaces to rolls is widely used around the world, and there is no need for particularly advanced welding methods to perform the work. The welding consumables and the way the welding is carried out is of more important character. The report will give some comments to this, and hopefully will give a short review of the current technology in this field.

  13. 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.

  14. 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. PMID:12582642

  15. 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).

  16. 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

  17. Cleaving machine for hard crystals

    NASA Technical Reports Server (NTRS)

    Benedicto, J. S. J.; Hallberg, F.

    1981-01-01

    Hard crystalline materials such as lithium fluoride (LiF) are cleaved in thin sections by semiautomatic machine. Yield of undistorted LiF crystals is almost 100 percent, even when cleaved section is only 1/32 inch thick. Machine contains spring-activated hammer that limits penetration of blade and controls shock that cleaves crystal. Fixture with spring-loaded clamps precisely locates and holds crystal, restraining it in ideal position for cleaving. Crystal then splays apart.

  18. Magnon softening in exchange-coupled hard-soft nanocomposites

    NASA Astrophysics Data System (ADS)

    Belemuk, A. M.; Chui, S. T.

    2013-03-01

    We study spin excitations of the fully aligned state for three-dimensional nanocomposites of exchange coupled hard (SmFeN) and soft (FeCo) phases. The dipolar interaction lowers the magnon energy and controls the spin wave gap at k = 0, which closes when the amount of soft phase exceeds a critical value. With the addition of soft phase or increasing temperature the system moves to another ground state characterized by a tilting of the magnetization at the boundaries between spins of the hard and the soft phases.

  19. PLD of hard ceramic coatings

    NASA Astrophysics Data System (ADS)

    Perera, Yibran; Gottmann, Jens; Husmann, Andreas; Klotzbuecher, Thomas; Kreutz, Ernst-Wolfgang; Poprawe, Reinhart

    2001-06-01

    The deposition of different hard ceramics coatings as Al2O3, ZrO2, c-BN and DLC thin films by pulsed laser deposition (PLD) has been of increasing interest as alternative process compared to the latest progress in CVD and PVD deposition. For instance, in pulsed laser deposition, the properties of the resulting thin films are influenced by the composition, ionization state, density, kinetic and excitation energies of the particles of the vapor/plasma. In order to deposit hard ceramics with different properties and applications, various substrates as Pt/Ti/Si multilayer, glass (fused silica), steel, polymethylmethacrylate (PMMA), polycarbonate (PC), Si(100) and Si(111) are used. These thin films are deposited either by excimer laser radiation ((lambda) equals 248 nm) or by CO2 laser radiation ((lambda) equals 10.6 micrometers ). To characterize the structural, optical and mechanical properties of the hard ceramics thin films, different techniques as Raman spectroscopy, ellipsometry, FTIR spectroscopy and nanoindentation are used.

  20. Comparison of time-dependent changes in the surface hardness of different composite resins

    PubMed Central

    Ozcan, Suat; Yikilgan, Ihsan; Uctasli, Mine Betul; Bala, Oya; Kurklu, Zeliha Gonca Bek

    2013-01-01

    Objective: The aim of this study was to evaluate the change in surface hardness of silorane-based composite resin (Filtek Silorane) in time and compare the results with the surface hardness of two methacrylate-based resins (Filtek Supreme and Majesty Posterior). Materials and Methods: From each composite material, 18 wheel-shaped samples (5-mm diameter and 2-mm depth) were prepared. Top and bottom surface hardness of these samples was measured using a Vicker's hardness tester. The samples were then stored at 37C and 100% humidity. After 24 h and 7, 30 and 90 days, the top and bottom surface hardness of the samples was measured. In each measurement, the rate between the hardness of the top and bottom surfaces were recorded as the hardness rate. Statistical analysis was performed by one-way analysis of variance, multiple comparisons by Tukey's test and binary comparisons by t-test with a significance level of P = 0.05. Results: The highest hardness values were obtained from each two surfaces of Majesty Posterior and the lowest from Filtek Silorane. Both the top and bottom surface hardness of the methacrylate based composite resins was high and there was a statistically significant difference between the top and bottom hardness values of only the silorane-based composite, Filtek Silorane (P < 0.05). The lowest was obtained with Filtek Silorane. The hardness values of all test groups increased after 24 h (P < 0.05). Conclusion: Although silorane-based composite resin Filtek Silorane showed adequate hardness ratio, the use of incremental technic during application is more important than methacrylate based composites. PMID:24966724

  1. Changes in copper water-effect ratios in toxicity tests conducted at varying water hardness levels

    SciTech Connect

    Cohen, A.S.; Brady, M.D.; Stubblefield, W.A.

    1995-12-31

    Side-by-side acute toxicity tests (Oncorhynchus mykiss and Ceriodaphnia dubia) were conducted in SITE waters collected from a western Montana river and in laboratory waters reconstituted to match the hardness and alkalinity of the SITE water samples. Tests were conducted according to USEPA guidance on the determination and use of Water-Effect Ratios (WER). Multiple WERS, calculated as the ratio of LC50 values from SITE and LAB water tests, were regressed against water hardness and provided significant correlations (r{sup 2}=0.7 to 0.8 (logarithmic)). WERs increased with decreasing water hardness ranging from 1.1 at 282 mg/l hardness to 8.9 at 60 mg/l hardness. Additional tests showed that WER values for single water samples tested at multiple hardness levels (samples augmented with calcium and magnesium salts) again significantly correlated with water hardness. These results are independent of the known ameliorating effect of water hardness on metals toxicity, since WERs compared LC50s for tests conducted at identical water hardness levels. One explanation for this hardness-WER relationship may be that both hardness and certain other toxicity-reducing water quality parameters (e.g., suspended solids, organic carbon) compete in providing protection from the toxic effects of metals in surface waters. As hardness decreases, the importance of these other water quality parameters may increase, thus enhancing the difference between toxicity in soft laboratory reconstituted waters (lacking organic enrichment or suspended solids) and soft site-waters. These results have potentially important implications for the application of national Ambient Water Quality Criteria (Gold Book values) to soft surface waters moderately enriched in organic carbon, suspended solids, or other toxicity-mitigating factors.

  2. 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 ...

  3. Charpy Impact Energy and Microindentation Hardness of 60-NITINOL

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.

    2012-01-01

    60-NITINOL (60 wt.% Ni 40 wt.% Ti) is being studied as a material for advanced aerospace components. The Charpy impact energy and microindentation hardness has been studied for this material, fabricated by vacuum induction skull melting (casting) and by hot isostatic pressing. Test specimens were prepared in various hardened and annealed heat treatment conditions. The average impact energy ranged from 0.33 to 0.49J for the hardened specimens while the annealed specimens had impact energies ranging from 0.89 to 1.18J. The average hardness values of the hardened specimens ranged from 590 to 676 HV while that of the annealed specimens ranged from 298 to 366 HV, suggesting an inverse relationship between impact energy and hardness. These results are expected to provide guidance in the selection of heat treatment processes for the design of mechanical components.

  4. Value Added?

    ERIC Educational Resources Information Center

    UCLA IDEA, 2012

    2012-01-01

    Value added measures (VAM) uses changes in student test scores to determine how much "value" an individual teacher has "added" to student growth during the school year. Some policymakers, school districts, and educational advocates have applauded VAM as a straightforward measure of teacher effectiveness: the better a teacher, the better students…

  5. 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,...

  6. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 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,...

  7. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 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...

  8. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 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,...

  9. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 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...

  10. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 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,...

  11. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 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,...

  12. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hard seeds. 201.57 Section 201.57 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard...

  13. 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...

  14. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 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...

  15. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hard seeds. 201.57 Section 201.57 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard...

  16. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hard seeds. 201.57 Section 201.57 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard...

  17. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hard seeds. 201.57 Section 201.57 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard...

  18. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 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...

  19. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hard seeds. 201.57 Section 201.57 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard...

  20. 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…

  1. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 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...

  2. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 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...

  3. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 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...

  4. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 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...

  5. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 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...

  6. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 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...

  7. 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...

  8. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 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...

  9. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 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...

  10. 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...

  11. Value of Fundamental Science

    NASA Astrophysics Data System (ADS)

    Burov, Alexey

    Fundamental science is a hard, long-term human adventure that has required high devotion and social support, especially significant in our epoch of Mega-science. The measure of this devotion and this support expresses the real value of the fundamental science in public opinion. Why does fundamental science have value? What determines its strength and what endangers it? The dominant answer is that the value of science arises out of curiosity and is supported by the technological progress. Is this really a good, astute answer? When trying to attract public support, we talk about the ``mystery of the universe''. Why do these words sound so attractive? What is implied by and what is incompatible with them? More than two centuries ago, Immanuel Kant asserted an inseparable entanglement between ethics and metaphysics. Thus, we may ask: which metaphysics supports the value of scientific cognition, and which does not? Should we continue to neglect the dependence of value of pure science on metaphysics? If not, how can this issue be addressed in the public outreach? Is the public alienated by one or another message coming from the face of science? What does it mean to be politically correct in this sort of discussion?

  12. Depth-independent hardness improvements in ion irradiated polystyrene

    SciTech Connect

    Rao, G.R.; Riester, L.; Lee, E.H.

    1994-12-31

    Polystyrene (PS) was irradiated with 2 MeV He{sup +} ions to a fluence of 3.3 {times} 10{sup 9} ions/m{sup 2}. A cross-section of the irradiated layer was subjected to hardness measurements across the section using a nanoindentation technique. Results showed that hardness increased as a function of irradiation depth and showed a maximum value of 12 GPa at a depth of approximately 6.5 {mu}m, for a total ion penetration range of 9 {mu}m, as compared to a hardness of 0.45 GPa for unirradiated PS. The hardness variation with depth followed the trend for Linear Energy Transfer (LET) for ionization from the energetic ions to substrate atoms. This investigation showed for the first time how hardness varies as a function of depth for ion-irradiated polymers; this variation approximately follows the ionization LET profile, suggesting that cross-linking in the polymers could be proportional to ionization.

  13. 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

  14. 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. PMID:22792282

  15. 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.

  16. Making Nozzles From Hard Materials

    NASA Technical Reports Server (NTRS)

    Wells, Dennis L.

    1989-01-01

    Proposed method of electrical-discharge machining (EDM) cuts hard materials like silicon carbide into smoothly contoured parts. Concept developed for fabrication of interior and exterior surfaces and internal cooling channels of convergent/divergent nozzles. EDM wire at skew angle theta creates hyperboloidal cavity in tube. Wire offset from axis of tube and from axis of rotation by distance equal to throat radius. Maintaining same skew angle as that used to cut hyperboloidal inner surface but using larger offset, cooling channel cut in material near inner hyperboloidal surface.

  17. Evaluation of colour and hardness changes of soft lining materials in food colorant solutions.

    PubMed

    Canay, S; Hersek, N; Tuluno?lu, I; Uzun, G

    1999-10-01

    The aim of this study was to measure the colour stability and viscoelastic properties of three commercially available soft lining materials in vitro, by exposing them to 3% erythrosine, tartrazine and sunset yellow solutions. The colour changes were determined using a computer controlled spectrophotometer. The colour change of three soft lining materials--Molloplast B, Flexor and Coe Super Soft--were determined after 1, 3 and 6 months storage in three different food colorant solutions. The colour changes of Molloplast B was not noticeable. Only the initial colour value of Flexor was significantly different from the other time interval colour measurements. On the other hand, the colour difference of Coe Super Soft was found to be significantly different at all comparative time interval measurements (P<0.05). According to Shore A hardness values, Molloplast B had an initial hardness of 44 in all three solutions, and there was a slight increase after 6 months. Flexor had an initial hardness of 39, at the end of 6 months the hardness changed a little. Coe Super Soft was fairly hard after processing and Shore A hardness was initially 89 which increased to 95 later on. According to these results, only the hardness values of Coe Super Soft showed a statistically significant difference when compared using Wilcoxon signed rank test at the P<0.05 level. As a conclusion, silicon type soft lining material seems to be more resistant to colour change and hardness than the acrylic type soft liners. PMID:10564440

  18. Are Short GRBs Really Hard?

    NASA Astrophysics Data System (ADS)

    Sakamoto, T.; Barbier, L.; Barthelmy, S.; Cummings, J.; Fenimore, E.; Gehrels, N.; Hullinger, D.; Krimm, H.; Markwardt, C.; Palmer, D.; Parsons, A.; Sato, G.; Tueller, J.; Aptekar, R.; Cline, T.; Golenetskii, S.; Mazets, E.; Pal'Shin, V.; Ricker, G.; Lamb, D.; Atteia, J.-L.; Swift-Bat; Konus-Wind; Hete-2 Team

    2006-05-01

    Thanks to the rapid position notice and response by HETE-2 and Swift, the X-ray afterglow emissions have been found for four recent short gamma-ray bursts (GRBs GRB 050509b, GRB 050709, GRB 050724, and GRB 050813). The positions of three out of four short GRBs are coincident with galaxies with no current or recent star formation. This discovery tightens the case for a different origin for short and long GRBs. On the other hand, from the prompt emission point of view, a short GRB shows a harder spectrum comparing to that of the long duration GRBs according to the BATSE observations. We investigate the prompt emission properties of four short GRBs observed by Swift/BAT. We found that the hardness of all four BAT short GRBs is in between the BATSE range for short and long GRBs. We will discuss the spectral properties of short GRBs including the short GRB sample of Konus-Wind and HETE-2 to understand the hard nature of the BATSE short GRBs.

  19. 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.

  20. Effect of various infection-control methods for light-cure units on the cure of composite resins.

    PubMed

    Chong, S L; Lam, Y K; Lee, F K; Ramalingam, L; Yeo, A C; Lim, C C

    1998-01-01

    This study (1) compared the curing-light intensity with various barrier infection-control methods used to prevent cross contamination, (2) compared the Knoop hardness value of cured composite resin when various barrier control methods were used, and (3) correlated the hardness of the composite resin with the light-intensity output when different infection-control methods were used. The light-cure unit tips were covered with barriers, such as cellophane wrap, plastic gloves, Steri-shields, and finger cots. The control group had no barrier. Composite resins were then cured for each of the five groups, and their Knoop hardness values recorded. The results showed that there was significant statistical difference in the light-intensity output among the five groups. However, there was no significant statistical difference in the Knoop hardness values among any of the groups. There was also no correlation between the Knoop hardness value of the composite resin with the light-intensity output and the different infection-control methods. Therefore, any of the five infection-control methods could be used as barriers for preventing cross-contamination of the light-cure unit tip, for the light-intensity output for all five groups exceeded the recommended value of 300 W/m2. However, to allow a greater margin of error in clinical situations, the authors recommend that the plastic glove or the cellophane wrap be used to wrap the light-cure tip, since these barriers allowed the highest light-intensity output. PMID:9656927

  1. Estimation of Young's modulus and of hardness by ultra-low load hardness tests with a Vickers indenter

    SciTech Connect

    Trindade, A.C. . Escola Superior de Tecnologia); Cavaleiro, A.; Fernandes, J.V. . Dept. de Engenharia Mecanica)

    1994-07-01

    The evaluation of the elastic-plastic properties of a material by using an ultra-low load hardness test requires a geometrical calibration that must take into account the imperfect form of the diamond indenter. In the present work, the Vickers indenter offset of the microindentation equipment was estimated using differently heat-treated steel samples. To this end, the dimensions of the indentations have been evaluated by two different methods: optical measurement of the diagonals and direct measurement of the penetration depth during the test. The elastic-plastic properties are then calculated from the analysis of the penetration depth/indentation load curves. The Young's modulus values determined for the different high-speed steel samples were very similar and close to the literature value for steel if the appropriate corrections are performed. The hardness values decrease when the determination procedure includes the geometrical correction of the indenter offset, and still further when using the total correction obtained by means of optical measurements of the indenter diagonal. Variation of the hardness values with the applied load is much less when the corrections are carried out.

  2. Added values.

    PubMed

    Trueland, Jennifer

    Values-based interviewing is an approach to recruitment that focuses on the job applicant's attitudes and behaviours and whether they are a good 'fit' for the organization.Used successfully by hospitals in the United States, the approach is being introduced to some NHS trusts. PMID:24734812

  3. Value Added

    ERIC Educational Resources Information Center

    Welch, Matt

    2004-01-01

    This article profiles retiring values teacher Gene Doxey and describes his foundational contributions to the students of California's Ramona Unified School District. Every one of the Ramona Unified School District's 7,200 students is eventually funneled through Doxey's Contemporary Issues class, a required rite of passage between elementary school…

  4. Adding Value.

    ERIC Educational Resources Information Center

    Orsini, Larry L.; Hudack, Lawrence R.; Zekan, Donald L.

    1999-01-01

    The value-added statement (VAS), relatively unknown in the United States, is used in financial reports by many European companies. Saint Bonaventure University (New York) has adapted a VAS to make it appropriate for not-for-profit universities by identifying stakeholder groups (students, faculty, administrators/support personnel, creditors, the…

  5. Value Added

    ERIC Educational Resources Information Center

    Welch, Matt

    2004-01-01

    This article profiles retiring values teacher Gene Doxey and describes his foundational contributions to the students of California's Ramona Unified School District. Every one of the Ramona Unified School District's 7,200 students is eventually funneled through Doxey's Contemporary Issues class, a required rite of passage between elementary school

  6. Redeeming Value.

    ERIC Educational Resources Information Center

    Whitwell, Stuart C. A.

    1995-01-01

    Presents an essay on organizational transformation and the way successful marketing transformations redeem a sense of value. Focuses on challenges faced by not-for-profit institutions, current changes in the library profession, and implications of the American Library Association's Goal 2000. A sidebar summarizes an interview with the director of

  7. Value Added

    ERIC Educational Resources Information Center

    Wilson, M. Roy

    2015-01-01

    With more than a thousand honors programs or colleges in the United States and that number growing every year, defining the value of honors is a significant undertaking. Honors seems to have become an obligatory upgrade that no college or university president can afford to be without, but there is more than institutional trending to be considered,…

  8. 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.

  9. Hard and fragile holmium-based bulk metallic glasses

    SciTech Connect

    Luo, Q.; Zhao, D.Q.; Pan, M.X.; Wang, R.J.; Wang, W.H.

    2006-05-01

    A family of holmium-based bulk metallic glasses (BMGs) with high glass-forming ability is obtained. The Ho-based BMGs exhibit much larger elastic moduli and high thermal stability in contrast to other known rare-earth (RE)-based BMGs. In particular, the BMGs show a large value of fragility. It is expected that the hard RE-based glasses with high glass-forming ability and fragile behaviors make them the appropriate candidate for glass transition study.

  10. Specific Energy of Hard Coal Under Load

    NASA Astrophysics Data System (ADS)

    Bogusz, Anna; Bukowska, Mirosława

    2015-03-01

    The article presents results of experimental tests of energy parameters of hard coals under loading, collected from research sites located within five main geologic structures of Upper Silesian Coal Basin (GZW) - Main Trough, Main Anticline, Bytom Trough, Rybnik Trough and Chwałowice Trough. Coals from12 mines were analysed, starting with seams of group 200, through groups 400, 500, 600 and, finally, seams of group 700. Coal of each of the groups of seams underwent uniaxial compression stress of the energy parameters, in a servo-controlled testing machine MTS-810NEW, for the full range of strain of the tested coal samples. Based on the tests the dependence of different types of specific energy of longitudinal strain of coals on the value of uniaxial compression strength was determined. The dependence of the value of dissipated energy and kinetic energy of coals on the uniaxial compression strength was described with a linear function, both for coals which due to their age belong to various bed sand for various lithotypes of coal. An increase in the value of dissipated energy and in kinetic energy was observed, which was correlated with an increase in uniaxial compression strength of coal. The share of dissipated energy is dominant in the total energy of strain. Share of recoverable energy in the total energy of strain is small, independent of the compression strength of coals and is at most a few per cent high. In coals of low strength and dominant share of dissipated energy, share of recoverable energy is the biggest among the tested coals. It was shown that following an increase in compression strength the share of recoverable energy decreases, while the share of dissipated energy in the total energy increases. Further studies of specific energy of longitudinal strain of rocks in the full-range strain will be the next step inperfecting methodology of research into natural rock burst susceptibility of Carboniferous rock mass and changes in the susceptibility resulting from mining activity.

  11. Indentation Load Effect on Young's Modulus and Hardness of Porous Sialon Ceramic by Depth Sensing Indentation Tests

    NASA Astrophysics Data System (ADS)

    Osman, Sahin

    2007-11-01

    Depth sensing indentation (DSI) tests at the range of 200-1800 mN are performed on porous sialon ceramic to determine the indentation load on Young's modulus and hardness values. The Young modulus and hardness (Dynamic and Martens) values are deduced by analysing the unloading segments of the DSI test load-displacement curves using the Oliver-Pharr method. It is found that Young's modulus Er, the dynamic hardness HD and the Martens hardness HM exhibit significant indentation load dependences. The values of Young's modulus and hardness decrease with the increasing indentation load, as a result of indentation load effect. The experimental hf/hm ratios lower than the critical value 0.7, with hm being the maximum penetration depth during loading and hf the final unloading depth, indicate that our sample shows the work hardening behaviour.

  12. Soft copy versus hard copy reading in digital mammography.

    PubMed

    Obenauer, Silvia; Hermann, Klaus-Peter; Marten, Katharina; Luftner-Nagel, Susanne; von Heyden, Dorit; Skaane, Per; Grabbe, Eckhardt

    2003-12-01

    The objective of this study was to compare soft copy reading at a mammography work station with hard copy reading of full-field digital mammographic images. Mammograms of 60 patients ( n = 29 malignant, n = 31 benign) performed with full-field digital mammography (Senographe 2000D, GE, Buc, France) were evaluated. Reading was performed based on hard copy prints (Scopix, Agfa, Leverkusen, Germany) and on 2 k x 2.5 k high-resolution monitors (Sun Ultra 60, Sun Microsystems, Palo Alto, California, USA). Four readers with different levels of experience in mammography categorized the mammograms according to the BI-RADS classification. The comparative study was performed by four readers, and at least 2 months elapsed between the reading sessions. Postprocessing, of course, was available only at the work station (windowing and leveling, zooming, inversion). Sensitivity, specificity, and positive predictive value were evaluated. Diagnostic accuracy of the evaluation was determined. Sensitivity for malignant lesions in hard copy versus soft copy reading was 97% vs 90%, 97% vs 97%, 93% vs 97%, and 76% vs 76% for the four readers, respectively. Specificity was 52% vs 68%, 58% vs 74%, 65% vs 48%, and 61% vs 68%. Accuracy for the classification of malignant lesions according to the BI-RADS categories showed no difference between hard copy and soft copy reading. Soft copy reading is possible with the available system and enables radiologists to use the advantages of a digital system. PMID:14749966

  13. 30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 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...

  14. 30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 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...

  15. 30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 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...

  16. 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...

  17. 30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 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...

  18. 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...

  19. 30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 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...

  20. 30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 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...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 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, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 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. Kinetics of hardness evolution during annealing of gamma-irradiated polycarbonate

    SciTech Connect

    Yeh, S. H.; Chen, P. Y.; Lee, Sanboh; Harmon, Julie

    2012-12-01

    This study focuses on the evolution in microhardness values that accompany isothermal annealing in gamma-irradiated polycarbonate (PC). Hardness increases with increasing annealing time, temperature, and gamma radiation dose. A model composed of a mixture of first and zero order structure relaxation is proposed to interpret the hardness data. The rate constant data fit the Arrhenius equation, and the corresponding activation energy decreases with increasing dose. The extent of structural relaxation that controls the hardness in post-annealed PC increases with increasing annealing temperature and dose. The model demonstrates that hardness evolution in PC is an endothermic process. By contrast, when the model is applied to irradiated poly(methyl methacrylate) and hydroxyethyl methacrylate copolymer, hardness evolution is an exothermic process.

  4. Maximum hardness and minimum polarizability principles through lattice energies of ionic compounds

    NASA Astrophysics Data System (ADS)

    Kaya, Savaş; Kaya, Cemal; Islam, Nazmul

    2016-03-01

    The maximum hardness (MHP) and minimum polarizability (MPP) principles have been analyzed using the relationship among the lattice energies of ionic compounds with their electronegativities, chemical hardnesses and electrophilicities. Lattice energy, electronegativity, chemical hardness and electrophilicity values of ionic compounds considered in the present study have been calculated using new equations derived by some of the authors in recent years. For 4 simple reactions, the changes of the hardness (Δη), polarizability (Δα) and electrophilicity index (Δω) were calculated. It is shown that the maximum hardness principle is obeyed by all chemical reactions but minimum polarizability principles and minimum electrophilicity principle are not valid for all reactions. We also proposed simple methods to compute the percentage of ionic characters and inter nuclear distances of ionic compounds. Comparative studies with experimental sets of data reveal that the proposed methods of computation of the percentage of ionic characters and inter nuclear distances of ionic compounds are valid.

  5. Measurements of the hard-x-ray reflectivity of iridium

    SciTech Connect

    Romaine, S.; Bruni, R.; Gorenstein, P.; Zhong, Z

    2007-01-10

    In connection with the design of a hard-x-ray telescope for the Constellation X-Ray Observatory we measured the reflectivity of an iridium-coated zerodur substrate as a function of angle at 55, 60, 70, and 80 keV at the National Synchrotron Light Source of Brookhaven National Laboratory. The optical constants were derived from the reflectivity data. The real component of the index of refraction is in excellent agreement with theoretical values at all four energies. However, the imaginary component, which is related to the mass attenuation coefficient, is 50% to 70% larger at 55, 60, and 70 keV than theoretical values.

  6. HARD RED SPRING WHEAT - 2001 CROP

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA/ARS Hard Red Spring and Durum Wheat Quality Laboratory evaluated 16 cultivars of hard red spring (HRS) wheat from the 2001 crop for kernel and milling properties, and subsequently shipped flour (and/or wheat) to overseas cooperators through arrangements made by US Wheat Associates (USW) for...

  7. 21 CFR 133.150 - Hard cheeses.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Hard cheeses. 133.150 Section 133.150 Food and... CONSUMPTION CHEESES AND RELATED CHEESE PRODUCTS Requirements for Specific Standardized Cheese and Related Products § 133.150 Hard cheeses. (a) The cheeses for which definitions and standards of identity...

  8. Hard Spring Wheat Technical Committee, 2008 Crop.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eleven hard spring wheat lines that were developed by breeders throughout the spring wheat region of the U. S. were grown at up to five locations in 2008 and evaluated for kernel, milling, and bread baking quality against the check variety Glenn. Samples of wheat were milled at the USDA Hard Red Sp...

  9. Retraction of Hard, Lozano, and Tversky (2006)

    ERIC Educational Resources Information Center

    Hard, B. M.; Lozano, S. C.; Tversky, B.

    2008-01-01

    Reports a retraction of "Hierarchical encoding of behavior: Translating perception into action" by Bridgette Martin Hard, Sandra C. Lozano and Barbara Tversky (Journal of Experimental Psychology: General, 2006[Nov], Vol 135[4], 588-608). All authors retract this article. Co-author Tversky and co-author Hard believe that the research results cannot…

  10. Hard Spring Wheat Technical Committee 2009 Crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thirteen hard spring wheat lines that were developed by breeders throughout the spring wheat region of the U. S. were grown at up to five locations in 2009 and evaluated for kernel, milling, and bread baking quality against the check variety Glenn. Samples of wheat were milled at the USDA Hard Red ...

  11. "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…

  12. HARD SPRING WHEAT TECHNICAL COMMITTEE 2007 CROP

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twelve experimental lines of hard spring wheat were grown at up to five locations in 2007 and evaluated for kernel, milling, and bread baking quality against the check variety Glenn. Samples of wheat were submitted through the Wheat Quality Council and processed and milled at the USDA Hard Red Spri...

  13. Valuing hope.

    PubMed

    McMillan, John; Walker, Simon; Hope, Tony

    2014-01-01

    This article argues that hope is of value in clinical ethics and that it can be important for clinicians to be sensitive to both the risks of false hope and the importance of retaining hope. However, this sensitivity requires an understanding of the complexity of hope and how it bears on different aspects of a well-functioning doctor-patient relationship. We discuss hopefulness and distinguish it, from three different kinds of hope, or 'hopes for', and then relate these distinctions back to differing accounts of autonomy. This analysis matters because it shows how an overly narrow view of the ethical obligations of a clinician to their patient, and autonomy, might lead to scenarios where patients regret the choices they make. PMID:25434063

  14. Implementing QML for radiation hardness assurance

    NASA Astrophysics Data System (ADS)

    Winokur, P. S.; Sexton, F. W.; Fleetwood, D. M.; Terry, M. D.; Shaneyfelt, M. R.

    1990-12-01

    The US government has proposed a qualified manufacturers list (QML) methodology to qualify integrated circuits for high reliability and radiation hardness. An approach to implementing QML for single-event upset (SEU) immunity on 16k SRAMs that involves relating values of feedback resistance to system error rates is demonstrated. It is seen that the process capability indices, Cp and Cpk, for the manufacture of 400-k-ohm feedback resistors required to provide SEU tolerance do not conform to 6 sigma quality standards. For total-dose, interface trap charge, Delta Vit, shifts measured on transistors are correlated with circuit response in the space environment. Statistical process control (SPC) is illustrated for Delta Vit, and violations of SPC rules are interpreted in terms of continuous improvement. Design validation for SEU and quality conformance inspections for total-dose are identified as major obstacles to cost-effective QML implementation. Techniques and tools that will help QML provide real cost savings are identified as physical models, 3-D device-plus-circuit codes, and improved design simulators.

  15. Effect of Substrates on Film Hardness Measurements of Nanometer Thick Amorphous Carbon Films

    NASA Astrophysics Data System (ADS)

    Akasaka, Hiroki; Ito, Hiroki; Nakano, Masayuki; Ohshio, Shigeo; Saitoh, Hidetoshi

    Amorphous carbon film (a-C:H) applications, such as hard disks, require films with nanometer thicknesses. In an indentation test, the obtained hardness values of these films are affected by substrates. On the indentation tests, we studied the effect of substrate hardness on films less than 200 nm in thickness. a-C:H and Si doped a-C:H (a-C:Si:H) films were deposited by electron cyclotron resonance plasma chemical vapor deposition onto aluminum (Al) and silicon (Si) substrates. The film thicknesses were approximately 140 nm. The hardnesses of the a-C:H film and substrates were obtained using a high-resolution indentation tester (pico-dentor) with a Vickers tip whose depth resolution was 0.04 nm. Maximum indentation loads were varied from 0.01 to 0.5 mN. The Martens hardnesses of films on the Al and Si substrates were 600 and 7000 N/mm2, respectively. On the a-C:Si:H film deposited on the Al substrate, the hardnesses increased from 1600 to 3900 N/mm2 with decreasing indentation load. The hardnesses of the films deposited on the Si substrate decreased from 5300 to 3500 N/mm2 when the maximum indentation loads were reduced. The effect of the substrates increased with the maximum load increasing. From these findings, the actual hardness value was determined to be 3600 N/mm2. These results indicate that the high-resolution indentation test achieved hardness estimations for nanometer-thick films with certain hardnesses.

  16. Valuing Stillbirths.

    PubMed

    Phillips, John; Millum, Joseph

    2015-07-01

    Estimates of the burden of disease assess the mortality and morbidity that affect a population by producing summary measures of health such as quality-adjusted life years (QALYs) and disability-adjusted life years (DALYs). These measures typically do not include stillbirths (fetal deaths occurring during the later stages of pregnancy or during labor) among the negative health outcomes they count. Priority-setting decisions that rely on these measures are therefore likely to place little value on preventing the more than three million stillbirths that occur annually worldwide. In contrast, neonatal deaths, which occur in comparable numbers, have a substantial impact on burden of disease estimates and are commonly seen as a pressing health concern. In this article we argue in favor of incorporating unintended fetal deaths that occur late in pregnancy into estimates of the burden of disease. Our argument is based on the similarity between late-term fetuses and newborn infants and the assumption that protecting newborns is important. We respond to four objections to counting stillbirths: (1) that fetuses are not yet part of the population and so their deaths should not be included in measures of population health; (2) that valuing the prevention of stillbirths will undermine women's reproductive rights; (3) that including stillbirths implies that miscarriages (fetal deaths early in pregnancy) should also be included; and (4) that birth itself is in fact ethically significant. We conclude that our proposal is ethically preferable to current practice and, if adopted, is likely to lead to improved decisions about health spending. PMID:25395144

  17. Valuing Stillbirths

    PubMed Central

    Phillips, John; Millum, Joseph

    2016-01-01

    Estimates of the burden of disease assess the mortality and morbidity that affect a population by producing summary measures of health such as quality-adjusted life years (QALYs) and disability-adjusted life years (DALYs). These measures typically do not include stillbirths (fetal deaths occurring during the later stages of pregnancy or during labor) among the negative health outcomes they count. Priority setting decisions that rely on these measures are therefore likely to place little value on preventing the more than three million stillbirths that occur annually worldwide. In contrast, neonatal deaths, which occur in comparable numbers, have a substantial impact on burden of disease estimates and are commonly seen as a pressing health concern. In this paper we argue in favor of incorporating unintended fetal deaths that occur late in pregnancy into estimates of the burden of disease. Our argument is based on the similarity between late-term fetuses and newborn infants and the assumption that protecting newborns is important. We respond to four objections to counting stillbirths: (1) that fetuses are not yet part of the population and so their deaths should not be included in measures of population health; (2) that valuing the prevention of stillbirths will undermine women’s reproductive rights; (3) that including stillbirths implies that miscarriages (fetal deaths early in pregnancy) should also be included; and (4) that birth itself is in fact ethically significant. We conclude that our proposal is ethically preferable to current practice and, if adopted, is likely to lead to improved decisions about health spending. PMID:25395144

  18. Hardness Evolution of Gamma-Irradiated Polyoxymethylene

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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.

  19. Valuing vaccination.

    PubMed

    Bärnighausen, Till; Bloom, David E; Cafiero-Fonseca, Elizabeth T; O'Brien, Jennifer Carroll

    2014-08-26

    Vaccination has led to remarkable health gains over the last century. However, large coverage gaps remain, which will require significant financial resources and political will to address. In recent years, a compelling line of inquiry has established the economic benefits of health, at both the individual and aggregate levels. Most existing economic evaluations of particular health interventions fail to account for this new research, leading to potentially sizable undervaluation of those interventions. In line with this new research, we set forth a framework for conceptualizing the full benefits of vaccination, including avoided medical care costs, outcome-related productivity gains, behavior-related productivity gains, community health externalities, community economic externalities, and the value of risk reduction and pure health gains. We also review literature highlighting the magnitude of these sources of benefit for different vaccinations. Finally, we outline the steps that need to be taken to implement a broad-approach economic evaluation and discuss the implications of this work for research, policy, and resource allocation for vaccine development and delivery. PMID:25136129

  20. Valuing vaccination

    PubMed Central

    Bärnighausen, Till; Bloom, David E.; Cafiero-Fonseca, Elizabeth T.; O’Brien, Jennifer Carroll

    2014-01-01

    Vaccination has led to remarkable health gains over the last century. However, large coverage gaps remain, which will require significant financial resources and political will to address. In recent years, a compelling line of inquiry has established the economic benefits of health, at both the individual and aggregate levels. Most existing economic evaluations of particular health interventions fail to account for this new research, leading to potentially sizable undervaluation of those interventions. In line with this new research, we set forth a framework for conceptualizing the full benefits of vaccination, including avoided medical care costs, outcome-related productivity gains, behavior-related productivity gains, community health externalities, community economic externalities, and the value of risk reduction and pure health gains. We also review literature highlighting the magnitude of these sources of benefit for different vaccinations. Finally, we outline the steps that need to be taken to implement a broad-approach economic evaluation and discuss the implications of this work for research, policy, and resource allocation for vaccine development and delivery. PMID:25136129

  1. Submicron cubic boron nitride as hard as diamond

    SciTech Connect

    Liu, Guoduan; Kou, Zili E-mail: yanxz@hpstar.ac.cn; Lei, Li; Peng, Fang; Wang, Qiming; Wang, Kaixue; Wang, Pei; Li, Liang; Li, Yong; Wang, Yonghua; Yan, Xiaozhi E-mail: yanxz@hpstar.ac.cn; Li, Wentao; Bi, Yan; Leng, Yang; He, Duanwei

    2015-03-23

    Here, we report the sintering of aggregated submicron cubic boron nitride (sm-cBN) at a pressure of 8 GPa. The sintered cBN compacts exhibit hardness values comparable to that of single crystal diamond, fracture toughness about 5-fold that of cBN single crystal, in combination with a high oxidization temperature. Thus, another way has been demonstrated to improve the mechanical properties of cBN besides reducing the grain size to nano scale. In contrast to other ultrahard compacts with similar hardness, the sm-cBN aggregates are better placed for potential industrial application, as their relative low pressure manufacturing perhaps be easier and cheaper.

  2. Recent results in the hard-tube MILO experiment

    SciTech Connect

    Haworth, M.; Baca, G.; Hendricks, K.; Shiffler, D.; Englert, T.; Henley, D.; LaCour, M.; Sena, M.; Lemke, R.

    1998-12-31

    The Hard-Tube MILO (Magnetically Insulated transmission Line Oscillator) is a gigawatt-class high-power microwave tube which employs conventional-tube brazing techniques rather than finger stock RF joints in its construction. The authors report on recent improvements made to the cathode and to the extractor in order to improve the shot-to-shot reproducibility of the tube by eliminating breakdown at triple points. Results from optimizing the impedance match of the extractor circuit to the tube, which has been predicted to increase the output power by up to 50%, are also presented. Finally, they report on Hard-Tube MILO results when using the recently upgraded IMP pulser. This upgrade gives the authors the potential to increase the output microwave pulse duration from its previously pulsed-power-limited value of 170 ns (FWHM) to nearly 500 ns.

  3. Holographic gravitational infall in the hard wall model

    NASA Astrophysics Data System (ADS)

    Craps, Ben; Lindgren, E. J.; Taliotis, Anastasios; Vanhoof, Joris; Zhang, Hongbao

    2014-10-01

    An infalling shell in the hard wall model provides a simple holographic model for energy injection in a confining gauge theory. Depending on its parameters, a scalar shell either collapses into a large black brane, or scatters between the hard wall and the anti-de Sitter boundary. In the scattering regime, we find numerical solutions that keep oscillating for as long as we have followed their evolution, and we provide an analytic argument that shows that a black brane can never be formed. This provides examples of states in infinite-volume field theory that never thermalize. We find that the field theory expectation value of a scalar operator keeps oscillating, with an amplitude that undergoes modulation.

  4. Plasma-assisted growth of bilayer silicon-containing coatings for hardness and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Xiao, Z. G.; Mantei, T. D.

    2004-07-01

    Hard corrosion-resistant bilayer coatings were grown in a high-density microwave electron cyclotron resonance discharge. The bilayer coatings consist of a relatively soft (0.6-1.5 GPa) polymer-like coating as the adherent bottom layer and a much harder (8-12 GPa) top layer. The polymer underlayers were grown from 100% octamethylcyclotetrasiloxane (OMCTS) while the hard top layer was either silicon dioxide grown from OMCTS in an oxygen plasma or silicon nitride grown from hexamethyldisiloxane in an ammonia plasma. The bilayer structures combined high surface hardness values with good corrosion resistance, surviving 1800-2600 h in an ASTM B117 salt-fog corrosion test. .

  5. Hard Choices for Individual Situations.

    ERIC Educational Resources Information Center

    Landon, Bruce

    This paper focuses on faculty use of a decision-making process for complex situations. The analysis part of the process describes and compares course management software focusing on: technical specifications, instructional design values,tools and features, ease of use, and standards compliance. The extensive comparisons provide faculty with…

  6. Influence of design variables on radiation hardness of silicon MINP solar cells

    NASA Technical Reports Server (NTRS)

    Anderson, W. A.; Solaun, S.; Rao, B. B.; Banerjee, S.

    1985-01-01

    Metal-insulator-N/P silicon (MINP) solar cells were fabricated using different substrate resistivity values, different N-layer designs, and different I-layer designs. A shallow junction into an 0.3 ohm-cm substrate gave best efficiency whereas a deeper junction into a 1 to 4 ohm-cm substrate gave improved radiation hardness. I-layer design variation did little to influence radiation hardness.

  7. Monte Carlo computer simulation of sedimentation of charged hard spherocylinders.

    PubMed

    Viveros-Méndez, P X; Gil-Villegas, Alejandro; Aranda-Espinoza, S

    2014-07-28

    In this article we present a NVT Monte Carlo computer simulation study of sedimentation of an electroneutral mixture of oppositely charged hard spherocylinders (CHSC) with aspect ratio L/σ = 5, where L and σ are the length and diameter of the cylinder and hemispherical caps, respectively, for each particle. This system is an extension of the restricted primitive model for spherical particles, where L/σ = 0, and it is assumed that the ions are immersed in an structureless solvent, i.e., a continuum with dielectric constant D. The system consisted of N = 2000 particles and the Wolf method was implemented to handle the coulombic interactions of the inhomogeneous system. Results are presented for different values of the strength ratio between the gravitational and electrostatic interactions, Γ = (mgσ)/(e(2)/Dσ), where m is the mass per particle, e is the electron's charge and g is the gravitational acceleration value. A semi-infinite simulation cell was used with dimensions Lx ≈ Ly and Lz = 5Lx, where Lx, Ly, and Lz are the box dimensions in Cartesian coordinates, and the gravitational force acts along the z-direction. Sedimentation effects were studied by looking at every layer formed by the CHSC along the gravitational field. By increasing Γ, particles tend to get more packed at each layer and to arrange in local domains with an orientational ordering along two perpendicular axis, a feature not observed in the uncharged system with the same hard-body geometry. This type of arrangement, known as tetratic phase, has been observed in two-dimensional systems of hard-rectangles and rounded hard-squares. In this way, the coupling of gravitational and electric interactions in the CHSC system induces the arrangement of particles in layers, with the formation of quasi-two dimensional tetratic phases near the surface. PMID:25084954

  8. Monte Carlo computer simulation of sedimentation of charged hard spherocylinders

    NASA Astrophysics Data System (ADS)

    Viveros-Méndez, P. X.; Gil-Villegas, Alejandro; Aranda-Espinoza, S.

    2014-07-01

    In this article we present a NVT Monte Carlo computer simulation study of sedimentation of an electroneutral mixture of oppositely charged hard spherocylinders (CHSC) with aspect ratio L/σ = 5, where L and σ are the length and diameter of the cylinder and hemispherical caps, respectively, for each particle. This system is an extension of the restricted primitive model for spherical particles, where L/σ = 0, and it is assumed that the ions are immersed in an structureless solvent, i.e., a continuum with dielectric constant D. The system consisted of N = 2000 particles and the Wolf method was implemented to handle the coulombic interactions of the inhomogeneous system. Results are presented for different values of the strength ratio between the gravitational and electrostatic interactions, Γ = (mgσ)/(e2/Dσ), where m is the mass per particle, e is the electron's charge and g is the gravitational acceleration value. A semi-infinite simulation cell was used with dimensions Lx ≈ Ly and Lz = 5Lx, where Lx, Ly, and Lz are the box dimensions in Cartesian coordinates, and the gravitational force acts along the z-direction. Sedimentation effects were studied by looking at every layer formed by the CHSC along the gravitational field. By increasing Γ, particles tend to get more packed at each layer and to arrange in local domains with an orientational ordering along two perpendicular axis, a feature not observed in the uncharged system with the same hard-body geometry. This type of arrangement, known as tetratic phase, has been observed in two-dimensional systems of hard-rectangles and rounded hard-squares. In this way, the coupling of gravitational and electric interactions in the CHSC system induces the arrangement of particles in layers, with the formation of quasi-two dimensional tetratic phases near the surface.

  9. Monte Carlo computer simulation of sedimentation of charged hard spherocylinders

    SciTech Connect

    Viveros-Méndez, P. X. Aranda-Espinoza, S.

    2014-07-28

    In this article we present a NVT Monte Carlo computer simulation study of sedimentation of an electroneutral mixture of oppositely charged hard spherocylinders (CHSC) with aspect ratio L/σ = 5, where L and σ are the length and diameter of the cylinder and hemispherical caps, respectively, for each particle. This system is an extension of the restricted primitive model for spherical particles, where L/σ = 0, and it is assumed that the ions are immersed in an structureless solvent, i.e., a continuum with dielectric constant D. The system consisted of N = 2000 particles and the Wolf method was implemented to handle the coulombic interactions of the inhomogeneous system. Results are presented for different values of the strength ratio between the gravitational and electrostatic interactions, Γ = (mgσ)/(e{sup 2}/Dσ), where m is the mass per particle, e is the electron's charge and g is the gravitational acceleration value. A semi-infinite simulation cell was used with dimensions L{sub x} ≈ L{sub y} and L{sub z} = 5L{sub x}, where L{sub x}, L{sub y}, and L{sub z} are the box dimensions in Cartesian coordinates, and the gravitational force acts along the z-direction. Sedimentation effects were studied by looking at every layer formed by the CHSC along the gravitational field. By increasing Γ, particles tend to get more packed at each layer and to arrange in local domains with an orientational ordering along two perpendicular axis, a feature not observed in the uncharged system with the same hard-body geometry. This type of arrangement, known as tetratic phase, has been observed in two-dimensional systems of hard-rectangles and rounded hard-squares. In this way, the coupling of gravitational and electric interactions in the CHSC system induces the arrangement of particles in layers, with the formation of quasi-two dimensional tetratic phases near the surface.

  10. TOXICITY OF COPPER TO CUTTHROAT TROUT ('SALMO CLARKI') UNDER DIFFERENT CONDITIONS OF ALKALINITY, PH, AND HARDNESS

    EPA Science Inventory

    Median lethal concentration (96-h LC50) values for acute copper toxicity to 3-10 g cutthroat trout (Salmo clarki) have been determined for nine different combinations of alkalinity, hardness, and pH. Equilibrium calculations were performed on the copper LC50 values; seven differe...

  11. Take a Long, Hard Look

    ERIC Educational Resources Information Center

    Mackney, Paul

    2008-01-01

    The mooted development of a set of core British values demands a thorough re-examination of what it means to be British. The author argues that British people need to look at Britishness a bit more as others see them. For many the experience of Britishness was brutishness and it is still seen that way in the Middle East and not just by those in…

  12. The turnaround value of values.

    PubMed

    Thorbeck, J

    1991-01-01

    John Thorbeck is an executive with a ten-year career history of successes--and a sense of repeated failure. Just out of business school, he was marketing director at the Aspen Skiing Company for three years and helped to reverse thirteen seasons of decline. At the Timberland shoe company in the mid-1980s, he led a marketing strategy that tripled sales. At the Bass shoe company, where he was CEO from 1987 to 1990, he took the company from big losses to big profits. Now he is president, CEO, and part owner of a third shoe company--Geo. E. Keith--that is surely the oldest, perhaps the smallest, and arguably the finest shoemaker in the United States. But the high points of Thorbeck's résumé conceal a leadership education that led him only slowly to abandon confrontational management in favor of management by history, values, competence, and what he calls organizational coherence. In his first two marketing jobs, he fought wars with his opponents and won. Then at Bass, he tried to recapture the company's proud past. He revived company folklore and history, gave workers back their pride in workmanship, and used this rejuvenated company spirit to meet and win new markets. Yet he was trying to take Bass someplace its owners simply wouldn't let it go, and he left the company profitable but divided, the work force eager to go one way, owenership another. In each of his jobs, Thorbeck overlooked some vital part of the organizational community.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:10109472

  13. 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.

  14. Hard x-ray imaging from explorer

    SciTech Connect

    Grindlay, J.E.; Murray, S.S.

    1981-11-01

    Coded aperture X-ray detectors were applied to obtain large increases in sensitivity as well as angular resolution. A hard X-ray coded aperture detector concept is described which enables very high sensitivity studies persistent hard X-ray sources and gamma ray bursts. Coded aperture imaging is employed so that approx. 2 min source locations can be derived within a 3 deg field of view. Gamma bursts were located initially to within approx. 2 deg and X-ray/hard X-ray spectra and timing, as well as precise locations, derived for possible burst afterglow emission. It is suggested that hard X-ray imaging should be conducted from an Explorer mission where long exposure times are possible.

  15. RAD hard PROM design study

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The results of a preliminary study on the design of a radiation hardened fusible link programmable read-only memory (PROM) are presented. Various fuse technologies and the effects of radiation on MOS integrated circuits are surveyed. A set of design rules allowing the fabrication of a radiation hardened PROM using a Si-gate CMOS process is defined. A preliminary cell layout was completed and the programming concept defined. A block diagram is used to describe the circuit components required for a 4 K design. A design goal data sheet giving target values for the AC, DC, and radiation parameters of the circuit is presented.

  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. 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. PMID:15353650

  19. Lasers processing of ultra-hard materials

    NASA Astrophysics Data System (ADS)

    Melaibari, Ammar Abdulghani

    Laser processing of ultra-hard materials is a relatively new field that have the potential to improve variety of products and different industries. This dissertation explores specific new development in this field through three main subjects: laser machining, laser deposition of thin film, and laser treatment. In laser machining of ultra-hard material, controlled crack propagation mechanism -as opposed to the typical ablation mechanism- was investigated, and micromachining of ultra-hard thin film was also observed. For the laser deposition of ultra-hard thin film, designing new microstructured materials was explored, and the utilization of the inherent particulate formation associated with the pulsed laser deposition process was proposed for the first time. After that, a novel laser/waterjet treatment process to increase the hardness of certain ceramic materials was studied. Also, laser shock processing was investigated. Analytical and experimental approaches was conducted through all of these studies, and different analysis techniques were applied. The results indicate the feasibility of these processes when applied on ultra-hard materials, and provide a better understanding of the governing mechanisms.

  20. Hard Gamma Ray Emission from the Starburst Galaxy NGC 253

    NASA Technical Reports Server (NTRS)

    Jackson, James M.; Marscher, Alan M.

    1996-01-01

    We have completed the study to search for hard gamma ray emission from the starburst galaxy NGC 253. Since supernovae are thought to provide the hard gamma ray emission from the Milky Way, starburst galaxies, with their extraordinarily high supernova rates, are prime targets to search for hard gamma ray emission. We conducted a careful search for hard gamma ray emission from NGC 253 using the archival data from the EGRET experiment aboard the CGRO. Because this starburst galaxy happens to lie near the South Galactic Pole, the Galactic gamma ray background is minimal. We found no significant hard gamma ray signal toward NGC 253, although a marginal signal of about 1.5 sigma was found. Because of the low Galactic background, we obtained a very sensitive upper limit to the emission of greater than 100 MeV gamma-rays of 8 x 10(exp -8) photons/sq cm s. Since we expected to detect hard gamma ray emission, we investigated the theory of gamma ray production in a dense molecular medium. We used a leaky-box model to simulate diffusive transport in a starburst region. Since starburst galaxies have high infrared radiation fields, we included the effects of self-Compton scattering, which are usually ignored. By modelling the expected gamma-ray and synchrotron spectra from NGC 253, we find that roughly 5 - 15% of the energy from supernovae is transferred to cosmic rays in the starburst. This result is consistent with supernova acceleration models, and is somewhat larger than the value derived for the Galaxy (3 - 10%). Our calculations match the EGRET and radio data very well with a supernova rate of 0.08/ yr, a magnetic field B approx. greater than 5 x 10(exp -5) G, a density n approx. less than 100/sq cm, a photon density U(sub ph) approx. 200 eV/sq cm, and an escape time scale tau(sub 0) approx. less than 10 Myr. The models also suggest that NGC 253 should be detectable with only a factor of 2 - 3 improvement in sensitivity. Our results are consistent with the standard picture of gamma-ray acceleration by supernovae.

  1. Hard and Soft Constraints in Reliability-Based Design Optimization

    NASA Technical Reports Server (NTRS)

    Crespo, L.uis G.; Giesy, Daniel P.; Kenny, Sean P.

    2006-01-01

    This paper proposes a framework for the analysis and design optimization of models subject to parametric uncertainty where design requirements in the form of inequality constraints are present. Emphasis is given to uncertainty models prescribed by norm bounded perturbations from a nominal parameter value and by sets of componentwise bounded uncertain variables. These models, which often arise in engineering problems, allow for a sharp mathematical manipulation. Constraints can be implemented in the hard sense, i.e., constraints must be satisfied for all parameter realizations in the uncertainty model, and in the soft sense, i.e., constraints can be violated by some realizations of the uncertain parameter. In regard to hard constraints, this methodology allows (i) to determine if a hard constraint can be satisfied for a given uncertainty model and constraint structure, (ii) to generate conclusive, formally verifiable reliability assessments that allow for unprejudiced comparisons of competing design alternatives and (iii) to identify the critical combination of uncertain parameters leading to constraint violations. In regard to soft constraints, the methodology allows the designer (i) to use probabilistic uncertainty models, (ii) to calculate upper bounds to the probability of constraint violation, and (iii) to efficiently estimate failure probabilities via a hybrid method. This method integrates the upper bounds, for which closed form expressions are derived, along with conditional sampling. In addition, an l(sub infinity) formulation for the efficient manipulation of hyper-rectangular sets is also proposed.

  2. The effect of rotational and translational energy exchange on tracer diffusion in rough hard sphere fluids.

    PubMed

    Kravchenko, Olga; Thachuk, Mark

    2011-03-21

    A study is presented of tracer diffusion in a rough hard sphere fluid. Unlike smooth hard spheres, collisions between rough hard spheres can exchange rotational and translational energy and momentum. It is expected that as tracer particles become larger, their diffusion constants will tend toward the Stokes-Einstein hydrodynamic result. It has already been shown that in this limit, smooth hard spheres adopt "slip" boundary conditions. The current results show that rough hard spheres adopt boundary conditions proportional to the degree of translational-rotational energy exchange. Spheres for which this exchange is the largest adopt "stick" boundary conditions while those with more intermediate exchange adopt values between the "slip" and "stick" limits. This dependence is found to be almost linear. As well, changes in the diffusion constants as a function of this exchange are examined and it is found that the dependence is stronger than that suggested by the low-density, Boltzmann result. Compared with smooth hard spheres, real molecules undergo inelastic collisions and have attractive wells. Rough hard spheres model the effect of inelasticity and show that even without the presence of attractive forces, the boundary conditions for large particles can deviate from "slip" and approach "stick." PMID:21428622

  3. Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

    NASA Astrophysics Data System (ADS)

    Umbrello, Domenico; Rizzuti, Stefania; Outeiro, José C.; Shivpuri, Rajiv

    2007-04-01

    In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

  4. Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

    SciTech Connect

    Umbrello, Domenico; Rizzuti, Stefania; Outeiro, Jose C.; Shivpuri, Rajiv

    2007-04-07

    In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

  5. Hard evidence on soft skills✩

    PubMed Central

    Heckman, James J.; Kautz, Tim

    2012-01-01

    This paper summarizes recent evidence on what achievement tests measure; how achievement tests relate to other measures of “cognitive ability” like IQ and grades; the important skills that achievement tests miss or mismeasure, and how much these skills matter in life. Achievement tests miss, or perhaps more accurately, do not adequately capture, soft skills—personality traits, goals, motivations, and preferences that are valued in the labor market, in school, and in many other domains. The larger message of this paper is that soft skills predict success in life, that they causally produce that success, and that programs that enhance soft skills have an important place in an effective portfolio of public policies. PMID:23559694

  6. A position sensitive phoswich hard X-ray detector system

    NASA Technical Reports Server (NTRS)

    Dean, A. J.; Hanson, C. G.; Hopkins, C. J.; Lewis, R. A.; Fraser-Mitchell, J.

    1985-01-01

    A prototype position sensitive phoswich hard X-ray detector, designed for eventual astronomical usage, was tested in the laboratory. The scintillation crystal geometry was designed on the basis of a Monte Carlo simulation of the internal optics and includes a 3mm thick NaI(T1) primary X-ray detector which is actively shielded by a 20 mm thick CsI(T1) scintillation crystal. This phoswich arrangement is viewed by a number two inch photomultipliers. Measured values of the positional and spectral resolution of incident X-ray photons are compared with calculation.

  7. Hard-sphere Yukawa fluid near a planar slit

    NASA Astrophysics Data System (ADS)

    Yi, Jong-Ho; Kim, Soon-Chul

    1997-11-01

    A density functional perturbative approximation, which is based on both the weighted-density approximation (WDA) of Tarazona and the density functional approximation of Rickayzen et al., has been employed to predict the density profiles of the hard-sphere attractive Yukawa fluid near a planar slit. The calculated density profiles show that the density functional perturbative approximation is a significant improvement upon those of the modified version of the Lovett-Mou-Buff-Wertheim (LMBW-1), which uses the exact contact value theorem, and compares very well with the computer simulation even for the low temperatures in the vicinity of the liquid-vapor fluid bulk transition.

  8. Review of hard copy systems for digital medical imaging

    NASA Astrophysics Data System (ADS)

    Apple, Bernard A.; Tennant, Mark H.; Thomas, Jule W., Jr.

    1996-03-01

    In this paper we review image requirements and the potential use of various printing technologies to record digital diagnostic radiographic information. An analysis of limitations and advantages of alternate imaging systems compared to current laser imager/silver halide film systems will be presented. The future move to digital radiology along with its hard copy requirements will also be discussed. The winning technologies in the market place will be determined by their ability to provide adequate image quality at low cost while meeting productivity, durability, and convenience requirements. The first technology to meet these requirements will have a tremendous advantage in the market place. Medical imaging hard copy is dominated by the use of silver halide media providing monochrome images of diagnostic image quality. As new digital medical imaging modalities have emerged they have opened the door to new hard copy technologies. These new technologies have been born and nurtured outside the medical market by small markets with high image quality requirements or by large markets with lower image quality requirements. The former have tended to provide high cost, high quality solutions and the latter low cost, low quality solutions. Silver halide media still dominates, at least in part, because it provides high image quality at a relatively low cost. Yet, the trend away from wet silver halide is evident. These new hard copy technologies are being tested to determine their applicability to the medical market and are finding niches where they provide value. A clear winner that provides the required image quality at low cost has yet to emerge.

  9. Effects of Water Hardness on Textile Detergency Performance in Aqueous Cleaning Systems.

    PubMed

    Gotoh, Keiko; Horibe, Kaori; Mei, Yang; Tsujisaka, Toshiyuki

    2016-02-01

    The effects of water hardness on textile detergency in aqueous solutions were systematically investigated using four surfactants: sodium oleate (OLNa), linear dodecylbenzene sulfonate (LAS), sodium dodecyl sulfate (AS), and polyoxyethylene (10) dodecyl ether (AE). Water hardness was adjusted according to the standard procedure described in IEC 60734:2012. As expected, by adding hardness salts the surface tension of the OLNa solution increased. Surprisingly, the addition of hardness salts lowers the surface tension for the LAS and AS solutions. In the case of the AE solution, hardness salt did not affect the surface tension. A decrease in transmittance and foamability after adding hardness salts was observed for every anionic surfactant solution, indicating that anionic surfactants can combine with divalent ions to form insoluble precipitates. Detergency experiments were performed using cotton plain-woven and towel fabrics soiled with a carbon black and oleic acid mixture. One piece each of untreated and soiled fabric were stacked and placed horizontally in detergent solution with or without hardness salts. As a mechanical action of soil removal, the shaking of 190 spm was applied. Soil removal and redeposition due to washing were evaluated from changes in values of the Kubelka-Munk function for both fabrics. With increasing water hardness, soil removal decreased and redeposition increased. In order of decreasing detergency, the surfactants were as follows: LAS > OLNa ≈ AS > AE. The results indicate that precipitates, formed by reaction of LAS or AS with hardness salts, are strongly adsorbed on the water surface because of their hydrophobicity, but they have no detergency power. The field emission scanning electron microscopic observation and X-ray photoelectron spectroscopic analysis showed that Ca(LAS)2 precipitation clung to fiber surfaces, and remained on the surfaces after washing. Significant changes in the cotton fabric due to washing were observed in mechanical properties and water absorbency. PMID:26782305

  10. Dielectric and hardness measurements of planetary analog rocks in support of in-situ subsurface sampling

    NASA Astrophysics Data System (ADS)

    ElShafie, Ahmed; Heggy, Essam

    2013-09-01

    Accurate assessment of the subsurface mechanical characteristics and how they correlate with dielectric properties is crucial to optimize future drilling and sampling investigations on planetary bodies. For 12 different types of basaltic rocks with different hardnesses, we use capacitive cells to measure the real part of the dielectric constant over the frequency range 100-1000 MHz, and a Schmidt hammer hardness tester to measure the hardness using a scale of 10-100. Our measurements suggest that the real part of the dielectric constant and rock hardness are linearly correlated. Additionally, sample hardness was linearly correlated to density. For a density ranging from 0.82 to 3.05 g/cm3, the real part of the dielectric constant ?? and rebound hardness values R ranged from ??=1.8-7.6 and R=14.16-68 for the different basalt samples. Hence, high dielectric constants imply a high rock hardness value and vice versa. We concluded that for volcanic surfaces that are analogous to the Martian surface as well as other planetary surfaces, there is an inverse correlation between drilling penetration rate based on the rotary-percussive drill method and the dielectric constant. Dielectric inversion from planetary radar probing experiments proposed herein is a crucial method to locate regions with lowest hardness and hence highest drilling penetration rate in desiccated volcanic planetary subsurfaces. The use of these cross-correlation measurements can optimize future drilling experiments and ensure that they reach their targets of opportunities, minimize losses in drilling performance, or the unnecessary use of power that will be needed for the continuity of the investigation.

  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. 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…

  13. 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).

  14. 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.

  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. 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

  17. Epidemiological study of hard metal asthma.

    PubMed Central

    Kusaka, Y; Iki, M; Kumagai, S; Goto, S

    1996-01-01

    OBJECTIVES: To elucidate factors contributing to hard metal asthma, the entire workforce of a corporation producing hard metal tools (n = 703) was examined. METHODS: The variables evaluated were the atopy reflected by immunoglobulin E (IgE) antibody against mite allergen, history of exposure to hard metal, smoking, concentration of airborne cobalt, specific IgE antibody reaction against cobalt, and the respiratory symptom of attacks of reversible dyspnoea with wheeze (asthmatic symptoms). RESULTS: Univariate analysis showed that the prevalence of the asthmatic symptoms was significantly higher in formerly and currently exposed male workers than in non-exposed male workers. Positive IgE reaction against cobalt was found in seven men (2.0%), all of whom had asthmatic symptoms. Furthermore, it was found that atopy, positive IgE antibody against cobalt, and age of 40 or older were significantly correlated with asthmatic symptoms. Multilogistic analysis on the same factors and smoking in all of the workers showed that the age, experience of hard metal exposure, and atopy were significant risk factors associated with the asthmatic symptoms. Multilogistic analysis of data for currently exposed and non-exposed workers also showed that age and atopy were risk factors, and that the exposure to cobalt at the low concentration (at or below 50 micrograms/m3) but not at the higher concentration was a significant risk factor. Exposure to mist of coolants containing ionic cobalt, used during grinding, was not found to be any more hazardous in terms of onset of asthmatic symptoms than exposure to hard metal dust containing metallic cobalt. CONCLUSIONS: Accordingly, it is concluded that both environmental factors and individual susceptibility should be taken into consideration in efforts to reduce the prevalence of hard metal asthma. PMID:8704860

  18. 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)…

  19. Fractal hard drives for quantum information

    NASA Astrophysics Data System (ADS)

    Wootton, James R.

    2016-02-01

    A quantum hard drive, capable of storing qubits for unlimited timescales, would be very useful for quantum computation. Unfortunately, the most ideal solutions currently known can only be built in a universe of four spatial dimensions. In a recent publication (Brell 2016 New J. Phys. 18 013050), Brell introduces a new family of models based on these ideal solutions. These use fractal lattices, and result in models whose Hausdorff dimension is less than 3. This opens a new avenue of research towards a quantum hard drive that can be build in our own 3D universe.

  20. Hard disks on the hyperbolic plane.

    PubMed

    Modes, Carl D; Kamien, Randall D

    2007-12-01

    We examine a simple hard disk fluid with no long range interactions on the two-dimensional space of constant negative Gaussian curvature, the hyperbolic plane. This geometry provides a natural mechanism by which global crystalline order is frustrated, allowing us to construct a tractable model of disordered monodisperse hard disks. We extend free-area theory and the virial expansion to this regime, deriving the equation of state for the system, and compare its predictions with simulation near an isostatic packing in the curved space. PMID:18233384

  1. Uniform shear flow in dissipative gases: Computer simulations of inelastic hard spheres and frictional elastic hard spheres

    NASA Astrophysics Data System (ADS)

    Astillero, Antonio; Santos, Andrés

    2005-09-01

    In the preceding paper, we have conjectured that the main transport properties of a dilute gas of inelastic hard spheres (IHSs) can be satisfactorily captured by an equivalent gas of elastic hard spheres (EHSs), provided that the latter are under the action of an effective drag force and their collision rate is reduced by a factor (1+α)/2 (where α is the constant coefficient of normal restitution). In this paper we test the above expectation in a paradigmatic nonequilibrium state, namely, the simple or uniform shear flow, by performing Monte Carlo computer simulations of the Boltzmann equation for both classes of dissipative gases with a dissipation range 0.5⩽α⩽0.95 and two values of the imposed shear rate a . It is observed that the evolution toward the steady state proceeds in two stages: a short kinetic stage (strongly dependent on the initial preparation of the system) followed by a slower hydrodynamic regime that becomes increasingly less dependent on the initial state. Once conveniently scaled, the intrinsic quantities in the hydrodynamic regime depend on time, at a given value of α , only through the reduced shear rate a*(t)∝a/T(t) , until a steady state, independent of the imposed shear rate and of the initial preparation, is reached. The distortion of the steady-state velocity distribution from the local equilibrium state is measured by the shear stress, the normal stress differences, the cooling rate, the fourth and sixth cumulants, and the shape of the distribution itself. In particular, the simulation results seem to be consistent with an exponential overpopulation of the high-velocity tail. These properties are common to both the IHS and EHS systems. In addition, the EHS results are in general hardly distinguishable from the IHS ones if α≳0.7 , so that the distinct signature of the IHS gas (higher anisotropy and overpopulation) only manifests itself at relatively high dissipations.

  2. 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…

  3. 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 institutional…

  4. Rad-Hard Microcontroller for Space Applications

    NASA Astrophysics Data System (ADS)

    Habinc, Sandi; Johansson, Fredrik; Sturesson, Fredrik; Simlastik, Martin; Hjorth, Magnus; Andersson, Jan; Redant, Steven; Sijbers, Wim; Thys, Geert; Monteleone, Claudio

    2015-09-01

    This paper describes a mixed-signal LEON3FT microcontroller ASIC (Application Specific Integrated Circuit) targeting embedded control applications with hard real-time requirements. The prototype device is currently in development at Cobham Gaisler, Sweden, and IMEC, Belgium, in the activity Microcontroller for embedded space applications, initiated and funded by the European Space Agency (ESA).

  5. 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.

  6. Playing Fields and Hard Surface Areas.

    ERIC Educational Resources Information Center

    Department of Education and Science, London (England).

    Guidelines are presented regarding the planning, layout, construction, and maintenance of outdoor playing fields for physical education. Consideration is given to the dual use of playing fields by the school and the community, the planning of hard surface playing areas, and specifications and bills of quantities. Maintenance costs of grass playing…

  7. 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 institutional

  8. Classic and Hard-Boiled Detective Fiction.

    ERIC Educational Resources Information Center

    Reilly, John M.

    Through an analysis of several stories, this paper defines the similarities and differences between classic and hard-boiled detective fiction. The characters and plots of three stories are discussed: "The Red House" by A. A. Milne; "I, The Jury" by Mickey Spillane; and "League of Frightened Men" by Rex Stout. The classic detective story is defined…

  9. Hard Spring Wheat Technical Committee 2006 Crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Breeders’ experimental lines of wheat are evaluated for overall quality before being released for commercial production. The Hard Spring Wheat Technical Committee provides milling and baking quality data on breeders’ experimental lines of wheat that are annually submitted to the Wheat Quality Counc...

  10. Ototraumatic effects of hard rock music.

    PubMed

    Reddell, R C; Lebo, C P

    1972-01-01

    Temporary and permanent shifts in auditory thresholds were found in 43 hard rock musicians and temporary shifts were also observed in some listeners. The threshold shifts involved all of the conventional puretone test frequencies. Custom-fitted polyvinyl chloride ear protectors were found to be effective in prevention of these noise-induced hearing losses. PMID:5008499

  11. Registration of Anton Hard White Winter Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Anton’ (Reg. No. CV PI 651043) hard white winter wheat (Triticum aestivum L.) was developed by the USDA-ARS and the Nebraska Agricultural Experiment Station and released in December, 2007. "Anton" was selected from the cross WA691213-27/N86L177//‘Platte’. Anton primarily was released for its lo...

  12. 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.

  13. Help! Libraries and the Hard of Hearing.

    ERIC Educational Resources Information Center

    1982

    This transcript contains the text of three speeches on the problems of people with hearing impairments and the provision of library services to the hard of hearing. Howard Edward (Rocky) Stone, founder of Self-Help-For-Hearing-Impaired-People, Inc., describes his difficulties as a hearing impaired person, the growing number of Americans with…

  14. Nanoindentation hardness and adhesion investigations of vapor deposited nanostructured diamond films

    NASA Astrophysics Data System (ADS)

    Catledge, Shane A.; Borham, James; Vohra, Yogesh K.; Lacefield, William R.; Lemons, Jack E.

    2002-04-01

    The effect of changing the N2/CH4 feedgas ratio on the structure and mechanical properties of microwave plasma chemical vapor deposited diamond films grown on Ti-6Al-4V alloy substrates was investigated. The relative concentration of CH4 and N2 (in a balance of H2) was shown to strongly influence film structure, hardness, and adhesion. For high CH4 concentration (15% by volume), nanostructured diamond films with roughness magnitudes of 15-30 nm, good adhesion and a high hardness value of 90 GPa was obtained. A distinct correlation was found between the nanoindentation hardness of the deposited film and the N2/CH4 ratio in the plasma, as well as a correlation of hardness to the ratio of the Raman peak intensities (1332 and 1555 cm-1). Scratch adhesion testing of nanostructured diamond films showed delamination at a critical force of 33 N using acoustic emission techniques. These results demonstrate that nanostructured diamond films can be tailored on metallic surfaces with hardness ranging from 10 GPa (medium-hard) to 100 GPa (superhard) and may be considered for wear resistant applications such as in the design of articulating medical implant devices.

  15. Evaluation of the Shore A hardness of silicone for facial prosthesis as to the effect of storage period and chemical disinfection.

    PubMed

    Guiotti, Aimée Maria; Goiato, Marcelo Coelho; dos Santos, Daniela Micheline

    2010-03-01

    The failure of facial prostheses is caused by limitations in the properties of existing materials, especially flexibility and durability. Therefore, this study evaluated the Shore A hardness of silicone used for fabrication of facial prostheses, Silastic MDX4-4210, according to the influence of storage period, daily disinfection, and 2 types of pigmentation. Thirty specimens were fabricated and divided in 3 groups: colorless, pigmented with makeup, and pigmented with iron oxide. Analysis of results was assessed on a Shore A hardness meter immediately, 6 months, and 1 year after fabrication of specimens, following the guidelines of the American Society for Testing and Materials. The hardness values were statistically analyzed by the Tukey test. The silicone exhibited an increase in hardness with time. However, the hardness was stable from 6 months to 1 year. It was concluded that the silicone is within the values of Shore A hardness reported in the literature, regardless of the storage period, pigmentation, and chemical disinfection. PMID:20186092

  16. Financial and environmental modelling of water hardness--implications for utilising harvested rainwater in washing machines.

    PubMed

    Morales-Pinzón, Tito; Lurueña, Rodrigo; Gabarrell, Xavier; Gasol, Carles M; Rieradevall, Joan

    2014-02-01

    A study was conducted to determine the financial and environmental effects of water quality on rainwater harvesting systems. The potential for replacing tap water used in washing machines with rainwater was studied, and then analysis presented in this paper is valid for applications that include washing machines where tap water hardness may be important. A wide range of weather conditions, such as rainfall (284-1,794 mm/year); water hardness (14-315 mg/L CaCO3); tap water prices (0.85-2.65 Euros/m(3)) in different Spanish urban areas (from individual buildings to whole neighbourhoods); and other scenarios (including materials and water storage capacity) were analysed. Rainfall was essential for rainwater harvesting, but the tap water prices and the water hardness were the main factors for consideration in the financial and the environmental analyses, respectively. The local tap water hardness and prices can cause greater financial and environmental impacts than the type of material used for the water storage tank or the volume of the tank. The use of rainwater as a substitute for hard water in washing machines favours financial analysis. Although tap water hardness significantly affects the financial analysis, the greatest effect was found in the environmental analysis. When hard tap water needed to be replaced, it was found that a water price of 1 Euro/m(3) could render the use of rainwater financially feasible when using large-scale rainwater harvesting systems. When the water hardness was greater than 300 mg/L CaCO3, a financial analysis revealed that an net present value greater than 270 Euros/dwelling could be obtained at the neighbourhood scale, and there could be a reduction in the Global Warming Potential (100 years) ranging between 35 and 101 kg CO2 eq./dwelling/year. PMID:24262990

  17. Heat treatment effect on microstructure, hardness and wear resistance of Cr26 white cast iron

    NASA Astrophysics Data System (ADS)

    Zhou, Shaoping; Shen, Yehui; Zhang, Hao; Chen, Dequan

    2015-01-01

    High chromium cast iron(HCCI) is taken as material of coal water slurry pump impeller, but it is susceptible to produce serious abrasive wear and erosion wear because of souring of hard coal particles. The research on optimization of heat treatments to improve abrasive wear properties of HCCI is insufficient, so effect of heat treatments on the microstructure, hardness, toughness, and wear resistance of Cr26 HCCI is investigated to determine the optimal heat treatment process for HCCI. A series of heat treatments are employed. The microstructures of HCCI specimens are examined by using optical microscopy and scanning electron microscopy. The hardness and impact fracture toughness of as-cast and heat treated specimens are measured. The wear tests are assessed by a Type M200 ring-on block wear tester. The results show the following: With increase of the quenching temperature from 950 °C to 1050 °C, the hardness of Cr26 HCCI increased to a certain value, kept for a time and then decreased. The optimal heat treatment process is 2 h quenching treatment at 1000 °C, followed by a subsequent 2 h tempering at 400 °C. The hardness of HCCI is related to the precipitation and redissolution of secondary carbides in the process of heat treatment. The subsequent tempering treatment would result in a slight decrease of hardness but increase of toughness. The wear resistance is much related to the "supporting" effect of the matrix and the "protective" effect of the hard carbide embedded in the matrix, and the wear resistance is further dependent on the hardness and the toughness of the matrix. This research can provide an important insight on developing an optimized heat treatment method to improve the wear resistance of HCCI.

  18. A study to evaluate cephalometric hard tissue profile of Tamil population for orthognathic surgery

    PubMed Central

    Nachiappan, S.; Tharanikumar, S.; Chandran, Ajay; Anusudha, P.; Nandini, G. D.; Balasubramaniam, Murali

    2015-01-01

    The primary aim of this study is to compare, the cephalometric hard tissue profile values and analysis between Tamil and Caucasian population. The study also aims to create a better understanding in the facial proportions of Tamil Nadu population and to have better diagnosis and treatment planning for orthognathic surgery for Tamil population in Tamil Nadu. PMID:26538943

  19. Note: equation of state and the freezing point in the hard-sphere model.

    PubMed

    Robles, Miguel; López de Haro, Mariano; Santos, Andrés

    2014-04-01

    The merits of different analytical equations of state for the hard-sphere system with respect to the recently computed high-accuracy value of the freezing-point packing fraction are assessed. It is found that the Carnahan-Starling-Kolafa and the branch-point approximant equations of state yield the best performance. PMID:24712819

  20. Measurement of blend concentrations of conventional and waxy hard wheats using NIR spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Breeding development of waxy hard wheat lines adapted to the North American climate has been underway for more than a decade, with releases of viable varieties imminent. Because of an anticipated premium value placed on waxy lots, a rapid and accurate method is desired to identify and quantify the m...

  1. Soft Power and Hard Measures: Large-Scale Assessment, Citizenship and the European Union

    ERIC Educational Resources Information Center

    Rutkowski, David; Engel, Laura C.

    2010-01-01

    This article explores the International Civic and Citizenship Education Study (ICCS) with particular emphasis on the European Union's (EU's) involvement in the regional portion. Using the ICCS, the EU actively combines hard measures with soft power, allowing the EU to define and steer cross-national rankings of values of EU citizenship. The

  2. Improvement of Quench Factor Analysis in Phase and Hardness Prediction of a Quenched Steel

    NASA Astrophysics Data System (ADS)

    Kianezhad, M.; Sajjadi, S. A.

    2013-05-01

    The accurate prediction of alloys' properties introduced by heat treatment has been considered by many researchers. The advantages of such predictions are reduction of test trails and materials' consumption as well as time and energy saving. One of the most important methods to predict hardness in quenched steel parts is Quench Factor Analysis (QFA). Classical QFA is based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. In this study, a modified form of the QFA based on the work by Rometsch et al. is compared with the classical QFA, and they are applied to prediction of hardness of steels. For this purpose, samples of CK60 steel were utilized as raw material. They were austenitized at 1103 K (830 °C). After quenching in different environments, they were cut and their hardness was determined. In addition, the hardness values of the samples were fitted using the classical and modified equations for the quench factor analysis and the results were compared. Results showed a significant improvement in fitted values of the hardness and proved the higher efficiency of the new method.

  3. The unconstrained local hardness: an intriguing quantity, beset by problems.

    PubMed

    Cuevas-Saavedra, Rogelio; Rabi, Nataly; Ayers, Paul W

    2011-11-21

    Developing a mathematical approach to the local hard/soft acid/base principle requires an unambiguous definition for the local hardness. One such quantity, which has aroused significant interest in recent years, is the unconstrained local hardness. Key identities are derived for the unconstrained local hardness, δμ/δρ(r). Several identities are presented which allow one to determine the unconstrained local hardness either explicitly using the hardness kernel and the inverse-linear response function, or implicitly by solving a system of linear equations. One result of this analysis is that the problem of determining the unconstrained local hardness is infinitely ill-conditioned because arbitrarily small changes in electron density can cause enormous changes in the chemical potential. This is manifest in the exponential divergence of the unconstrained local hardness as one moves away from the system. This suggests that one should be very careful when using the unconstrained local hardness for chemical interpretation. PMID:21984043

  4. Influence of pre-heat treatment and different light-curing units on Vickers hardness of a microhybrid composite resin

    NASA Astrophysics Data System (ADS)

    Saade, E. G.; Bandeca, M. C.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-06-01

    The aim of this study was to evaluate the hardness of a dental composite resin submitted to temperature changes before photo-activation with two light-curing unite (LCUs). Five samples (4 mm in diameter and 2 mm in thickness) for each group were made with pre-cure temperatures of 37, 54, and 60°C. The samples were photo-activated with a conventional quartz-tungsten-halogen (QTH) and blue LED LCUs during 40 s. The hardness Vickers test (VHN) was performed on the top and bottom surfaces of the samples. According to the interaction between light-curing unit and different pre-heating temperatures of composite resin, only the light-curing unit provided influences on the mean values of initial Vickers hardness. The light-curing unit based on blue LED showed hardness mean values more homogeneous between the top and bottom surfaces. The hardness mean values were not statistically significant difference for the pre-cure temperature used. According to these results, the pre-heating of the composite resin provide no influence on Vickers hardness mean values, however the blue LED showed a cure more homogeneous than QTH LCU.

  5. 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.

  6. Hard-on-Hard Lubrication in the Artificial Hip under Dynamic Loading Conditions

    PubMed Central

    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. PMID:23940772

  7. The BQP-hardness of approximating the Jones polynomial

    NASA Astrophysics Data System (ADS)

    Aharonov, Dorit; Arad, Itai

    2011-03-01

    A celebrated important result due to Freedman et al (2002 Commun. Math. Phys. 227 605-22) states that providing additive approximations of the Jones polynomial at the kth root of unity, for constant k=5 and k>=7, is BQP-hard. Together with the algorithmic results of Aharonov et al (2005) and Freedman et al (2002 Commun. Math. Phys. 227 587-603), this gives perhaps the most natural BQP-complete problem known today and motivates further study of the topic. In this paper, we focus on the universality proof; we extend the result of Freedman et al (2002) to ks that grow polynomially with the number of strands and crossings in the link, thus extending the BQP-hardness of Jones polynomial approximations to all values to which the AJL algorithm applies (Aharonov et al 2005), proving that for all those values, the problems are BQP-complete. As a side benefit, we derive a fairly elementary proof of the Freedman et al density result, without referring to advanced results from Lie algebra representation theory, making this important result accessible to a wider audience in the computer science research community. We make use of two general lemmas we prove, the bridge lemma and the decoupling lemma, which provide tools for establishing the density of subgroups in SU(n). Those tools seem to be of independent interest in more general contexts of proving the quantum universality. Our result also implies a completely classical statement, that the multiplicative approximations of the Jones polynomial, at exactly the same values, are #P-hard, via a recent result due to Kuperberg (2009 arXiv:0908.0512). Since the first publication of those results in their preliminary form (Aharonov and Arad 2006 arXiv:quant-ph/0605181), the methods we present here have been used in several other contexts (Aharonov and Arad 2007 arXiv:quant-ph/0702008; Peter and Stephen 2008 Quantum Inf. Comput. 8 681). The present paper is an improved and extended version of the results presented by Aharonov and Arad (2006) and includes discussions of the developments since then.

  8. Equilibration and generalized Gibbs ensemble for hard wall boundary conditions

    NASA Astrophysics Data System (ADS)

    Goldstein, Garry; Andrei, Natan

    2015-10-01

    In this work we present an analysis of a quench for the repulsive Lieb-Liniger gas confined to a large box with hard wall boundary conditions. We study the time average of local correlation functions and show that both the quench action approach and the generalized Gibbs ensemble formalism are applicable for the long-time average of local correlation functions. We find that the time average of the system corresponds to an eigenstate of the Lieb-Liniger Hamiltonian and that this eigenstate is related to an eigenstate of a Lieb-Liniger Hamiltonian with periodic boundary conditions on an interval of twice the length and with twice as many particles (a doubled system). We further show that local operators with support far away from the boundaries of the hard wall have the same expectation values with respect to this eigenstate as corresponding operators for the doubled system. We present an example of a quench where the gas is initially confined in several moving traps and then released into a bigger container, an approximate description of the Newton's cradle experiment. We calculate the time average of various correlation functions for long times after the quench.

  9. Packing of hard spheres in cylinders and applications

    NASA Astrophysics Data System (ADS)

    Mughal, Adil; Weaire, Denis; Hutzler, Stefan; Chan, Ho Kei

    2014-03-01

    We study the optimal packing of hard spheres in an infinitely long cylinder. Our simulations have yielded dozens of periodic, mechanically stable, structures as the ratio of the cylinder (D) to sphere (d) diameter is varied. Up to D/d =2.715 the densest structures are composed entirely of spheres which are in contact with the cylinder. The density reaches a maximum at discrete values of D/d when a maximum number of contacts are established. These maximal contact packings are of the classic ``phyllotactic'' type, familiar in biology. However, between these points we observe another type of packing, termed line-slip. An analytic understanding of these rigid structures follows by recourse to a yet simpler problem: the packing of disks on a cylinder. We show that maximal contact packings correspond to the perfect wrapping of a honeycomb arrangement of disks around a cylindrical tube. While line-slip packings are inhomogeneous deformations of the honeycomb lattice modified to wrap around the cylinder. Beyond D/d =2.715 the structures are more complex, since they incorporate internal spheres. We review some relevant experiments with hard spheres, small bubbles and discuss similar structures found in nature. We discuss the chirality of these packings and potential applications in photonics.

  10. Characterization of Hard Piezoelectric Lead-Free Ceramics

    PubMed Central

    Zhang, Shujun; Lim, Jong Bong; Lee, Hyeong Jae; Shrout, Thomas R.

    2010-01-01

    K4CuNb8O23 doped K0.45Na0.55NbO3 (KNN-KCN) ferroelectric ceramics were found to exhibit asymmetrical polarization hysteresis loops, related to the development of an internal bias field. The internal bias field is believed to be the result of defect dipoles of acceptor ions and oxygen vacancies, which lead to piezoelectric “hardening” effect, by stabilizing and pinning of the domain wall motion. The dielectric loss for the hard lead-free piezoelectric ceramic was found to be 0.6%, with mechanical quality factors Q on the order of >1500. Furthermore, the piezoelectric properties were found to decrease and the coercive field increased, when compared with the undoped material, exhibiting a typical characteristic of “hard” behavior. The temperature usage range was limited by the polymorphic phase transition temperature, being 188°C. The full set of material constants was determined for the KNN-KCN materials. Compared with conventional hard PZT ceramics, the lead-free possessed lower dielectric and piezoelectric properties; however, comparable values of mechanical Q, dielectric loss, and coercive fields were obtained, making acceptor modified KNN based lead-free piezoelectric material promising for high-power applications, where lead-free materials are desirable. PMID:19686966

  11. Hard Spheres on the Primitive Surface

    NASA Astrophysics Data System (ADS)

    Dotera, Tomonari; Takahashi, Yusuke

    2015-03-01

    Recently hierarchical structures associated with the gyroid in several soft-matter systems have been reported. One of fundamental questions is regular arrangement or tiling on minimal surfaces. We have found certain numbers of hard spheres per unit cell on the gyroid surface are entropically self-organized. Here, new results for the primitive surface are presented. 56/64/72 per unit cell on the primitive minimal surface are entropically self-organized. Numerical evidences for the fluid-solid transition as a function of hard sphere radius are obtained in terms of the acceptance ratio of Monte Carlo moves and order parameters. These arrangements, which are the extensions of the hexagonal arrangement on a flat surface, can be viewed as hyperbolic tiling on the Poincaré disk with a negative Gaussian curvature.

  12. Hard diffraction with dynamic gap survival

    NASA Astrophysics Data System (ADS)

    Rasmussen, Christine O.; Sjöstrand, Torbjörn

    2016-02-01

    We present a new framework for the modelling of hard diffraction in pp and poverline{p} collisions. It starts from the the approach pioneered by Ingelman and Schlein, wherein the single diffractive cross section is factorized into a Pomeron flux and a Pomeron PDF. To this it adds a dynamically calculated rapidity gap survival factor, derived from the modelling of multiparton interactions. This factor is not relevant for diffraction in ep collisions, giving non-universality between HERA and Tevatron diffractive event rates. The model has been implemented in P ythia 8 and provides a complete description of the hadronic state associated with any hard single diffractive process. Comparisons with poverline{p} and pp data reveal improvement in the description of single diffractive events.

  13. 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.

  14. 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.

  15. Structure of Rigid Hard-Ring Fluids

    NASA Astrophysics Data System (ADS)

    Nouri, Mariam; Robert, Marc

    2011-03-01

    Structure of fluids of molecules consisting of rigid rings of hard spheres is studied in two, quasi two, and three dimensions, using Monte Carlo computer simulations in the canonical ensemble. For rings of various size and for a wide range of densities, results are reported for the pair distribution function of the ring centers and for the pair distribution of the ring orientations. For dense fluids in two dimensions, a shoulder, precursor of the freezing transition, is observed in the second peak of the pair distribution function of the ring centers, as previously seen in the simple hard-sphere fluid. In quasi two dimensions, where the centers of the rings are confined to a plane but the rings themselves can wobble out of plane, a liquid crystalline nematic phase is observed at sufficiently high densities. Results are also presented for three dimensions.

  16. 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.

  17. 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.

  18. Hard spheres on the gyroid surface.

    PubMed

    Dotera, Tomonari; Kimoto, Masakiyo; Matsuzawa, Junichi

    2012-10-01

    We find that 48/64 hard spheres per unit cell on the gyroid minimal surface are entropically self-organized. Striking evidence is obtained in terms of the acceptance ratio of Monte Carlo moves and order parameters. The regular tessellations of the spheres can be viewed as hyperbolic tilings on the Poincaré disc with a negative Gaussian curvature, one of which is, equivalently, the arrangement of angels and devils in Escher's Circle Limit IV. PMID:24098841

  19. 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 5. Section 6 presents the organization of the hardness assurance within a project. Section 7 discusses emerging radiation hardness assurance issues.

  20. Hardness enhancement in nanocrystalline tantalum thin films

    SciTech Connect

    Nieh, Tai-Gang; Yang, Bing; Zhang, Ming; Chu, Jinn P

    2006-01-01

    Nanocrystalline tantalum thin film was prepared by radio frequency magnetron sputtering on a glass substrate. Structure and mechanical properties of the as-deposited thin film were investigated by X-ray diffraction, transmission electron microscopy, and nanoindentation. The salient feature in the present tantalum thin film with a grain size of 76.5 nm is the remarkable enhancement of hardness, about one order of magnitude higher than that of bulk coarse-grained tantalum.

  1. Threshold corrections to hard supersymmetric relations

    NASA Astrophysics Data System (ADS)

    Giardino, Pier Paolo; Lodone, Paolo

    2014-06-01

    We compute the one-loop threshold corrections to hard supersymmetric relations involving gauge and gaugino couplings for the case of a Split-SUSY-like spectrum with moderate splitting. We show that these contributions are small, however in principle they will typically have to be taken into account if the heavy scalar sector is below 100 TeV and if one reaches, at future linear colliders, the precision that is necessary to perform this kind of measurements.

  2. 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.

  3. Nanotwinned diamond with unprecedented hardness and stability

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  4. 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.

  5. Arsenic, nitrate, iron, and hardness in ground water, Chena Ridge vicinity, Fairbanks, Alaska

    USGS Publications Warehouse

    Krumhardt, Andrea P.

    1979-01-01

    The report presents all data on hardness, iron, nitrate and arsenic in well water in the Chena Ridge area of Fairbanks, Alaska, through June 1979. Concentrations range as follows: arsenic - 0 to 28 micrograms per liter; nitrate - 0 to 20 milligrams per liter; iron - 0 to 18 milligrams per liter and hardness - 72 to 1,400 milligrams per liter. Values at the upper ends of the ranges for iron and nitrate exceed limits recommended by the Environmental Protection Agency for public water supplies. A map of the area showing the location of sampled wells and a table of chemical analysis are included. (Kosco-USGS)

  6. Hardness variability in commercial and hardened technologies

    SciTech Connect

    Shaneyfelt, M.R.; Winokur, P.S.; Meisenheimer, T.L.; Sexton, F.W.; Roeske, S.B.; Knoll, M.G.

    1994-03-01

    Over the past 10 years, there have been a number of advances in methods to assess and assure the radiation hardness of microelectronics in military and space applications. At the forefront of these is the Qualified Manufacturers List (QML) methodology, in which the hardness of product is ``built-in`` through statistical process control (SPC) of technology parameters relevant to the radiation response, test structure to integrated circuit (IC) correlations, and techniques for extrapolating laboratory test results to varying radiation scenarios. At the same time, there has been renewed interest in the use of commercial technology -- with its enhanced performance, reduced cost, and higher reliability -- in military and space systems. In this paper, we initially demonstrate the application of QML techniques to assure and control the radiation response of hardened technologies. Through several examples, we demonstrate intra-die, wafer-to-wafer, and lot-to-lot variations in a hardened technology. We observe 10 to 30% variations in key technology parameters that result from variability in geometry, process, and design layout. Radiation-induced degradation is seen to mirror preirradiation characteristics. We then evaluate commercial technologies and report considerably higher variability in radiation hardness, i.e., variations by a factor of two to five. This variability is shown to arise from a lack of control of technology parameters relevant to the radiation response, which a commercial manufacturer has no interest in controlling in a normal process flow.

  7. Magnetic hyperthermia with hard-magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kashevsky, Bronislav E.; Kashevsky, Sergey B.; Korenkov, Victor S.; Istomin, Yuri P.; Terpinskaya, Tatyana I.; Ulashchik, Vladimir S.

    2015-04-01

    Recent clinical trials of magnetic hyperthermia have proved, and even hardened, the Ankinson-Brezovich restriction as upon magnetic field conditions applicable to any site of human body. Subject to this restriction, which is harshly violated in numerous laboratory and small animal studies, magnetic hyperthermia can relay on rather moderate heat source, so that optimization of the whole hyperthermia system remains, after all, the basic problem predetermining its clinical perspectives. We present short account of our complex (theoretical, laboratory and small animal) studies to demonstrate that such perspectives should be related with the hyperthermia system based on hard-magnetic (Stoner-Wohlfarth type) nanoparticles and strong low-frequency fields rather than with superparamagnetic (Brownian or Neél) nanoparticles and weak high-frequency fields. This conclusion is backed by an analytical evaluation of the maximum absorption rates possible under the field restriction in the ideal hard-magnetic (Stoner-Wohlarth) and the ideal superparamagnetic (single relaxation time) systems, by theoretical and experimental studies of the dynamic magnetic hysteresis in suspensions of movable hard-magnetic particles, by producing nanoparticles with adjusted coercivity and suspensions of such particles capable of effective energy absorption and intratumoral penetration, and finally, by successful treatment of a mice model tumor under field conditions acceptable for whole human body.

  8. Hardness variability in commercial and hardened technologies

    NASA Astrophysics Data System (ADS)

    Shaneyfelt, M. R.; Winokur, P. S.; Meisenheimer, T. L.; Sexton, F. W.; Roeske, S. B.; Knoll, M. G.

    1994-01-01

    Over the past 10 years, there have been a number of advances in methods to assess and assure the radiation hardness of microelectronics in military and space applications. At the forefront of these is the Qualified Manufacturers List (QML) methodology, in which the hardness of product is 'built-in' through statistical process control (SPC) of technology parameters relevant to the radiation response, test structure to integrated circuit (IC) correlations, and techniques for extrapolating laboratory test results to varying radiation scenarios. At the same time, there has been renewed interest in the use of commercial technology -- with its enhanced performance, reduced cost, and higher reliability -- in military and space systems. In this paper, we initially demonstrate the application of QML techniques to assure and control the radiation response of hardened technologies. Through several examples, we demonstrate intra-die, wafer-to-wafer, and lot-to-lot variations in a hardened technology. We observe 10 to 30% variations in key technology parameters that result from variability in geometry, process, and design layout. Radiation-induced degradation is seen to mirror preirradiation characteristics. We then evaluate commercial technologies and report considerably higher variability in radiation hardness, i.e., variations by a factor of two to five. This variability is shown to arise from a lack of control of technology parameters relevant to the radiation response, which a commercial manufacturer has no interest in controlling in a normal process flow.

  9. Hard-tip, soft-spring lithography.

    PubMed

    Shim, Wooyoung; Braunschweig, Adam B; Liao, Xing; Chai, Jinan; Lim, Jong Kuk; Zheng, Gengfeng; Mirkin, Chad A

    2011-01-27

    Nanofabrication strategies are becoming increasingly expensive and equipment-intensive, and consequently less accessible to researchers. As an alternative, scanning probe lithography has become a popular means of preparing nanoscale structures, in part owing to its relatively low cost and high resolution, and a registration accuracy that exceeds most existing technologies. However, increasing the throughput of cantilever-based scanning probe systems while maintaining their resolution and registration advantages has from the outset been a significant challenge. Even with impressive recent advances in cantilever array design, such arrays tend to be highly specialized for a given application, expensive, and often difficult to implement. It is therefore difficult to imagine commercially viable production methods based on scanning probe systems that rely on conventional cantilevers. Here we describe a low-cost and scalable cantilever-free tip-based nanopatterning method that uses an array of hard silicon tips mounted onto an elastomeric backing. This method-which we term hard-tip, soft-spring lithography-overcomes the throughput problems of cantilever-based scanning probe systems and the resolution limits imposed by the use of elastomeric stamps and tips: it is capable of delivering materials or energy to a surface to create arbitrary patterns of features with sub-50-nm resolution over centimetre-scale areas. We argue that hard-tip, soft-spring lithography is a versatile nanolithography strategy that should be widely adopted by academic and industrial researchers for rapid prototyping applications. PMID:21270890

  10. Hard and soft spectral states of ULXs

    NASA Astrophysics Data System (ADS)

    Soria, R.

    2011-05-01

    I discuss some differences between the observed spectral states of ultraluminous X-ray sources (ULXs) and the canonical scheme of spectral states defined in Galactic black holes. The standard interpretation of ULXs with a curved spectrum, or a moderately steep power-law with soft excess and high-energy downturn, is that they are an extension of the very high state, up to luminosities {≈ 1}-3 L_Edd. Two competing models are Comptonization in a warm corona, and slim disk; I suggest bulk motion Comptonization in the radiatively-driven outflow as another possibility. The interpretation of ULXs with a hard power-law spectrum is more problematic. Some of them remain in that state over a large range of luminosities; others switch directly to a curved state without going through a canonical high/soft state. I suggest that those ULXs are in a high/hard state not seen in Galactic black holes; that state may overlap with the low/hard state at lower accretion rates, and extend all the way to Eddington accretion rates. If some black holes can reach Eddington accretion rates without switching to a standard-disk-dominated state, it is also possible that they never quench their steady jets.

  11. Hard pellicle study for 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Shu, Emily Y.; Lo, Fu-Chang; Eschbach, Florence O.; Cotte, Eric P.; Engelstad, Roxann L.; Lovell, Edward G.; Okada, Kaname; Kikugawa, Shinya

    2002-07-01

    Identifying a functional pellicle solution for 157-nm lithography remains the most critical issue for mask technology. Developing a hard pellicle system has been a recent focus of study. Fabrication and potential pellicle-induced image placement errors present the highest challenges to the technology for meeting the stringent error budget for manufacturing devices in the 65-nm regime. This paper reports the results of a comprehensive proof-of-concept study on the state-of-art hard pellicle systems, which feature 800-mm thick modified fused silica pellicles and quartz frames. Pellicles were fabricated to ensure optical uniformity and flatness. Typical intrinsic warpage of these pellicles was close to the theoretical limit of 4.0 mm under a gravitational load. Quartz frames had bows less than 1.0 mm. The advantage of quartz frames with matched thermal expansion was demonstrated. An interferometric facility was developed to measure the flatness of the mask and pellicle system before and after pellicle mounting. Depending on the mounting process as well as mounting tool characteristics and techniques, variations were observed from pellicle to pellicle, mount to mount, and mask to mask. A redesign of the mounter and mounting process has significantly improved pellicle flatness. Finite element models were also generated to characterize the relative importance of the principal sources of pellicle-induced photomask distortions. Simulation results provide insightful guidance for improving image quality when employing a hard pellicle.

  12. New Hardness Results for Diophantine Approximation

    NASA Astrophysics Data System (ADS)

    Eisenbrand, Friedrich; Rothvoß, Thomas

    We revisit simultaneous Diophantine approximation, a classical problem from the geometry of numbers which has many applications in algorithms and complexity. The input to the decision version of this problem consists of a rational vector α ∈ ℚ n , an error bound ɛ and a denominator bound N ∈ ℕ + . One has to decide whether there exists an integer, called the denominator Q with 1 ≤ Q ≤ N such that the distance of each number Q ·α i to its nearest integer is bounded by ɛ. Lagarias has shown that this problem is NP-complete and optimization versions have been shown to be hard to approximate within a factor n c/ loglogn for some constant c > 0. We strengthen the existing hardness results and show that the optimization problem of finding the smallest denominator Q ∈ ℕ + such that the distances of Q·α i to the nearest integer are bounded by ɛ is hard to approximate within a factor 2 n unless {textrm{P}} = NP.

  13. Solving the hard problem of Bertrand's paradox

    NASA Astrophysics Data System (ADS)

    Aerts, Diederik; de Bianchi, Massimiliano Sassoli

    2014-08-01

    Bertrand's paradox is a famous problem of probability theory, pointing to a possible inconsistency in Laplace's principle of insufficient reason. In this article, we show that Bertrand's paradox contains two different problems: an "easy" problem and a "hard" problem. The easy problem can be solved by formulating Bertrand's question in sufficiently precise terms, so allowing for a non-ambiguous modelization of the entity subjected to the randomization. We then show that once the easy problem is settled, also the hard problem becomes solvable, provided Laplace's principle of insufficient reason is applied not to the outcomes of the experiment, but to the different possible "ways of selecting" an interaction between the entity under investigation and that producing the randomization. This consists in evaluating a huge average over all possible "ways of selecting" an interaction, which we call a universal average. Following a strategy similar to that used in the definition of the Wiener measure, we calculate such universal average and therefore solve the hard problem of Bertrand's paradox. The link between Bertrand's problem of probability theory and the measurement problem of quantum mechanics is also briefly discussed.

  14. The Experiences of Non-Signing Deaf and Hard-of-Hearing Students and Their Academic and Social Integration into a Primarily Signing Deaf University Environment

    ERIC Educational Resources Information Center

    Dorminy, Jerri Lyn

    2013-01-01

    What is the value of a predominantly signing Deaf University such as Gallaudet University for an oral deaf or hard-of-hearing non-signing student who grew up in the mainstreamed or inclusive educational settings? This study sought to explore the experiences of ten non-signing oral deaf and hard-of-hearing university students as they integrated,…

  15. Process for casting hard-faced, lightweight camshafts and other cylindrical products

    DOEpatents

    Hansen, Jeffrey S.; Turner, Paul C.; Argetsinger, Edward R.; Wilson, Rick D.

    1996-01-01

    A process for casting a hard-faced cylindrical product such as an automobile camshaft includes the steps of: (a) preparing a composition formed from a molten base metal and an additive in particle form and having a hardness value greater than the hardness value of the base metal; (b) introducing the composition into a flask containing a meltable pattern of a cylindrical product such as an automobile camshaft to be manufactured and encased in sand to allow the composition to melt the pattern and assume the shape of the pattern within the sand; and (c) rotating the flask containing the pattern about the longitudinal axes of both the flask and the pattern as the molten base metal containing the additive in particle form is introduced into the flask to cause particles of the additive entrained in the molten base metal to migrate by centrifugal action to the radial extremities of the pattern and thereby provide a cylindrical product having a hardness value greater at it's radial extremities than at its center when the molten base metal solidifies.

  16. 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-performance signal processing include significant increase in onboard science data processing, enabling orders of magnitude reduction in required communication bandwidth for science data return, orders of magnitude improvement in onboard mission planning and critical decision making, and the ability to rapidly respond to changing mission environments, thus enabling opportunistic science and orders of magnitude reduction in the cost of mission operations through reduction of required staff. Additional benefits of COTS-based, high-performance signal processing include the ability to leverage considerable commercial and academic investments in advanced computing tools, techniques, and infra structure, and the familiarity of the science and IT community with these computing environments.

  17. The electronic structure of hard materials

    NASA Astrophysics Data System (ADS)

    Winarski, Robert Paul

    This research dissertation involves an experimental as well as a theoretical examination of the electronic structure of hard materials. The materials that are presented in this dissertation cover a wide class of materials, consisting of transition metal borides, irradiated polymer films, theoretically predicted superhard semiconductors, doped intermetallic alloys, and transition metal carbides. The borides are traditionally used in high temperature, hard coating applications, such as rocket nozzle linings, extreme wear surfaces, and corrosion coatings. Measurements of the borides appear to show that the bonding in these hard materials is primarily between the boron atoms in these systems. Also of note are the remarkably short interatomic distances between the boron atoms and between the boron and metal atoms in these materials. Irradiated polymer films are being developed for electronic applications, in the hopes that circuits can be developed that can benefit from the high thermal stability, dielectric properties, and mechanical properties provided by these materials. C3N4 is a theoretically predicted superhard material, and some of the first soft x-ray emission measurements of well-characterized samples of this compound are discussed in this work. Intermetallic alloys, in particular Ni3Al, are rather hard, but brittle metallic alloys. It has been found that the addition of boron atoms, in rather low concentrations, can increase the ductility of these alloys, allowing them to be utilized in a wider variety of applications. Measurements of this system have examined a question regarding the positioning of the boron atoms in the structures of this alloy. Finally, the transition metal carbides are used extensively as coatings in industrial applications such as cutting and grinding tools, and polishing compounds. Measurements of these materials suggest that the high degree of covalency between the metal and carbon atoms is primarily responsible for the hardness of these materials. Using soft x-ray emission and absorption spectroscopy I have probed the occupied and unoccupied states of these materials. Comparisons of these measurements were made to theoretical calculations performed using the linear muffin-tin orbital (LMTO-ASA) and full potential (FPLASTO) methods.

  18. A hard pill to swallow: medication, empathy, and the value of collaborative recovery.

    PubMed

    Bizub, Anne L

    2013-06-01

    Recovery from mental illness is a complex journey that is greatly facilitated when client and professional helper collaborate in the decision making process. It is further aided when the latter has an empathetic awareness of the client's experience, especially with regard to the impact of pharmacological treatment. The following article describes one psychologist's experience of being prescribed medication during a period of acute illness. Analysis of this experience is via a narrative, phenomenological approach. Results suggest that even when taken as directed, a medication can augment one's subjective feeling of illness. It further shows how challenging it can be for the ailing individual to assert his or her needs for something other than hospitalization. Although only one case is analyzed, it points to the impact that medication may have on the life of a person with mental illness, reinforcing the importance of collaboration and empathetic understanding of the other's experience. PMID:23014794

  19. Stopping the Brain Drain of Skilled Veteran Teachers: Retaining and Valuing Their Hard-Won Experience

    ERIC Educational Resources Information Center

    Fibkins, William L.

    2011-01-01

    Veteran educators are being encouraged to take early retirement in order to create jobs for less-experienced, lower-paid novices. Veteran educators are not alone: early retirement promotions have become the norm for aging workers in America. Consequently, there is a brain-drain of skilled workers at the national, state, and local levels. The early

  20. The gray-scale ink-jet printer: value in making hard copies of digital images.

    PubMed

    Combs, M J; Snell, J; Cail, W S; Maier, T; Buck, D A

    1995-01-01

    Referring physicians often are supplied with copies of images to illustrate a report of the findings of a radiologic study or so that the radiologist can retain the original images. The increasing costs of production, film, and recovery of chemicals have enhanced the requirement for a clean, low-cost dry printing process. An ink-jet gray-scale paper printer (Unitone, Scitex Medical Systems, Bedford, MA) can print high-quality (300 dots per inch [dpi]) images with an effective 10-bit gray scale range by using the Hertz continuous ink-jet method [1-3], which does not require the use of a darkroom or hazardous chemicals. Several types of media (matte paper, glossy paper, transparency film) with a printing area of 26.9 x 43.7 cm (10.6 x 17.4 inches) may be used. The consumables are approximately 50-70% less expensive than the cost of silver halide film, providing a cost advantage over film for referral and archival copies. The results of an initial evaluation of the ink-jet printer at our institution are reported here. PMID:7998544

  1. Stopping the Brain Drain of Skilled Veteran Teachers: Retaining and Valuing Their Hard-Won Experience

    ERIC Educational Resources Information Center

    Fibkins, William L.

    2011-01-01

    Veteran educators are being encouraged to take early retirement in order to create jobs for less-experienced, lower-paid novices. Veteran educators are not alone: early retirement promotions have become the norm for aging workers in America. Consequently, there is a brain-drain of skilled workers at the national, state, and local levels. The early…

  2. Hard X-ray Microscopic Images of the Human Hair

    NASA Astrophysics Data System (ADS)

    Goo, Jawoong; Jeon, Soo Young; Oh, Tak Heon; Hong, Seung Phil; Yon, Hwa Shik; Lee, Won-Soo

    2007-01-01

    The better visualization of the human organs or internal structure is challenging to the physicist and physicians. It can lead to more understanding of the morphology, pathophysiology and the diagnosis. Conventionally used methods to investigate cells or architectures, show limited value due to sample processing procedures and lower resolution. In this respect, Zernike type phase contrast hard x-ray microscopy using 6.95keV photon energy has advantages. We investigated hair fibers of the normal healthy persons. Coherence based phase contrast images revealed three distinct structures of hair, medulla, cortex, and cuticular layer. Some different detailed characters of each sample were noted. And further details would be shown and these results would be utilized as basic data of morphologic study of human hair.

  3. The effect of cold spray impact velocity on deposit hardness

    NASA Astrophysics Data System (ADS)

    Champagne, Victor K.; Helfritch, Dennis J.; Trexler, Matthew D.; Gabriel, Brian M.

    2010-09-01

    The deposition and consolidation of metal powders by means of cold spray is a method where powder particles are accelerated to high velocity through entrainment in a gas undergoing expansion in a de Laval nozzle and are subsequently impacted upon a surface. The impacted powder particles form a consolidated structure which can be several centimeters thick. The characteristics of this structure depend on the initial characteristics of the metal powder and upon impact velocity. Initially soft particles are strain hardened during impact, resulting in a structure that can have a hardness value greater than that which can be achieved by conventional cold working. A materials model is proposed for these phenomena, and model calculation is compared with experimental data from cold sprayed copper and aluminum.

  4. Hard X-ray Microscopic Images of the Human Hair

    SciTech Connect

    Goo, Jawoong; Jeon, Soo Young; Oh, Tak Heon; Hong, Seung Phil; Lee, Won-Soo; Yon, Hwa Shik

    2007-01-19

    The better visualization of the human organs or internal structure is challenging to the physicist and physicians. It can lead to more understanding of the morphology, pathophysiology and the diagnosis. Conventionally used methods to investigate cells or architectures, show limited value due to sample processing procedures and lower resolution. In this respect, Zernike type phase contrast hard x-ray microscopy using 6.95keV photon energy has advantages. We investigated hair fibers of the normal healthy persons. Coherence based phase contrast images revealed three distinct structures of hair, medulla, cortex, and cuticular layer. Some different detailed characters of each sample were noted. And further details would be shown and these results would be utilized as basic data of morphologic study of human hair.

  5. Virial Coefficients for the Hard Gaussian Overlap Model

    NASA Astrophysics Data System (ADS)

    Huang, Ssu-Li; Bhethanabotla, Venkat R.

    Monte Carlo estimates of virial coefficients up to the sixth for the Hard Gaussian Overlap (HGO) model are presented for values of the aspect ratio parameter κ of the model ranging from 0.05 to 10. The sixth coefficients are new and the lower coefficients are improvements on previous numerical estimates. The second virials are found to be in excellent agreement with an analytical integration reported in the literature. Padé (3, 3) approximations to the pressure and residual Helmholtz energy were constructed. Attempts to represent coefficients in these approximations by analytical functions of κ were not successful due to singularities in these functions. In the approximate range of 4.5≤κ≤ 5.5, the (3, 3) Padé approximations were found to be no better than lower ones. Comparisons with available Monte Carlo simulated pressures for moderately aspherical fluids were found to be good.

  6. Simple monoclinic crystal phase in suspensions of hard ellipsoids

    NASA Astrophysics Data System (ADS)

    Pfleiderer, P.; Schilling, T.

    2007-02-01

    We present a computer simulation study on the crystalline phases of hard ellipsoids of revolution. For aspect ratios ⩾3 the previously suggested stretched-fcc phase [Frenkel and Mulder, Mol. Phys. 55, 1171 (1985)] is replaced by a different crystalline phase. Its unit cell contains two ellipsoids with unequal orientations. The lattice is simple monoclinic. The angle of inclination of the lattice, β , is a very soft degree of freedom, while the two right angles are stiff. For one particular value of β , the close-packed version of this crystal is a specimen of the family of superdense packings recently reported [Donev , Phys. Rev. Lett. 92, 255506 (2004)]. These results are relevant for studies of nucleation and glassy dynamics of colloidal suspensions of ellipsoids.

  7. Microstructure and hardness development in a copper-nickel diffusion gradient model system

    NASA Astrophysics Data System (ADS)

    Duchstein, L. D. L.; Zhang, X.; Hansen, N.

    2015-08-01

    Cu has been electrolytically coated with Ni and subsequently deformed by rotary swaging up to a strain of e=2 to create a chemical gradient at the interface of the two elements. The extend of this chemical intermixing has been investigated through Energy Dispersive X- ray (EDX) spectroscopy in the Scanning and Transmission Electron Microscope (SEM and TEM). The depth, in which intermixing takes place, is about 1pm from the interface. Because of the uniform deformation, the structure does not get elongated but rather uniformly reduced in size. Microindentation hardness measurement shows a hardness increase from 120 to 135kp/mm2 in the Cu phase with increasing strain. After annealing at 200°C for up to 4h the hardness first decreases, but raises above the value for the highly strained sample. The experimental findings are discussed with emphasis on surface mechanical alloying as a process of both scientific and technological interest.

  8. The Value of Reciprocity

    ERIC Educational Resources Information Center

    Molm, Linda D.; Schaefer, David R.; Collett, Jessica L.

    2007-01-01

    The value of reciprocity in social exchange potentially comprises both instrumental value (the value of the actual benefits received from exchange) and communicative or symbolic value (the expressive and uncertainty reduction value conveyed by features of the act of reciprocity itself). While all forms of exchange provide instrumental value, we…

  9. Values for Educational Leadership

    ERIC Educational Resources Information Center

    Haydon, Graham

    2007-01-01

    What are values? Where do our values come from? How do our values make a difference in education? For educational leaders to achieve distinction in their practice, it is vital to establish clear personal values rather than reacting to the implicit values of others. This engaging book guides readers in considering the values they bring to their…

  10. The material co-construction of hard science fiction and physics

    NASA Astrophysics Data System (ADS)

    Hasse, Cathrine

    2015-12-01

    This article explores the relationship between hard science fiction and physics and a gendered culture of science. Empirical studies indicate that science fiction references might spur some students' interest in physics and help develop this interest throughout school, into a university education and even further later inspire the practice of doing science. There are many kinds of fiction within the science fiction genre. In the presented empirical exploration physics students seem particularly fond of what is called `hard science fiction': a particular type of science fiction dealing with technological developments (Hartwell and Cramer in The hard SF renaissance, Orb/TOR, New York, 2002). Especially hard science fiction as a motivating fantasy may, however, also come with a gender bias. The locally materialized techno-fantasies spurring dreams of the terraforming of planets like Mars and travels in time and space may not be shared by all physics students. Especially female students express a need for other concerns in science. The entanglement of physics with hard science fiction may thus help develop some students' interest in learning school physics and help create an interest for studying physics at university level. But research indicates that especially female students are not captured by the hard techno-fantasies to the same extent as some of their male colleagues. Other visions (e.g. inspired by soft science fiction) are not materialized as a resource in the local educational culture. It calls for an argument of how teaching science is also teaching cultural values, ethics and concerns, which may be gendered. Teaching materials, like the use of hard science fiction in education, may not just be (yet another) gender bias in science education but also carrier of particular visions for scientific endeavours.

  11. Equation of State and Integral Equation Theory for Hard Sphere and Hard-Sphere Chain Fluids.

    NASA Astrophysics Data System (ADS)

    Chang, Jaeeon

    The development of an accurate equation of state based on molecular thermodynamics for simple and complex fluids is important to chemical process design. In this dissertation we study the thermodynamic and intermolecular structural properties of hard sphere and hard-sphere chain fluids. These are theoretically challenging problems, the solution of which are useful for perturbation theory of more realistic potential models. We obtain a real expression for the radial distribution function of the hard sphere fluid up to the third shell by transforming Baxter's integral equation into a recursive differential equation. With this expression we develop a completely analytic perturbation equation of state for the square-well fluid to second order. This equation of state is used to predict the critical properties and vapor -liquid equilibria of square-well fluids of variable well width, and also to predict the thermodynamic behavior of real fluids, including neon, argon, and methane. We next develop a modified version of the thermodynamic perturbation theory, referred to as TPT-dimer theory, for the hard-sphere chain fluid by incorporating intermolecular structural information for the diatomic fluid. To test this theory, we performed Monte Carlo simulations for a bulk hard-sphere chain fluid, and obtained the compressibility factor using Nezbeda's pressure equation. When compared with the simulation results obtained in this research, the TPT-dimer equations of state are found to be accurate both at low and high densities. The correlation functions of homonuclear hard -sphere chain fluids are studied using the Wertheim integral equation theory for associating fluids and the Monte Carlo simulation method. In the Wertheim theory such a chain molecule is described by associating hard spheres with two independent attraction sites. The OZ-like equation for this system is analytically solved using the polymer -PY closure and the single bonding approximation, and we obtain accurate predictions for both the inter- and overall correlation functions for chains up to 16-mers. The TPT -dimer and Wertheim integral equation theories are generalized to mixtures of homonuclear hard-sphere chain fluids. From comparison with the computer simulation results for several mixtures, those theories are found to be very accurate tools to estimate the pressure and correlation functions of hard-sphere chain mixtures.

  12. Valuing Opportunities to Learn

    ERIC Educational Resources Information Center

    Bullock, Quintin B.

    2015-01-01

    With community colleges in the national spotlight as never before, a lot of talk has focused on the excellent work that community colleges are doing to help students succeed, especially the inroads that community colleges are making among their most academically vulnerable students. Thanks to the efforts of hard-working, dedicated faculty and…

  13. 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.

  14. 21 CFR 133.148 - Hard grating cheeses.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Hard grating cheeses. 133.148 Section 133.148 Food... Related Products § 133.148 Hard grating cheeses. (a) The cheeses for which definitions and standards of identity are prescribed by this section are hard grating cheeses for which specifically...

  15. 21 CFR 133.148 - Hard grating cheeses.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Hard grating cheeses. 133.148 Section 133.148 Food... Related Products § 133.148 Hard grating cheeses. (a) The cheeses for which definitions and standards of identity are prescribed by this section are hard grating cheeses for which specifically...

  16. Interfacial free energy of a hard-sphere fluid in contact with curved hard surfaces.

    PubMed

    Laird, Brian B; Hunter, Allie; Davidchack, Ruslan L

    2012-12-01

    Using molecular-dynamics simulation, we have calculated the interfacial free energy γ between a hard-sphere fluid and hard spherical and cylindrical colloidal particles, as functions of the particle radius R and the fluid packing fraction η=ρσ(3)/6, where ρ and σ are the number density and hard-sphere diameter, respectively. These results verify that Hadwiger's theorem from integral geometry, which predicts that γ for a fluid at a surface, with certain restrictions, should be a linear combination of the average mean and Gaussian surface curvatures, is valid within the precision of the calculation for spherical and cylindrical surfaces up to η ≈ 0.42. In addition, earlier results for γ for this system [Bryk et al., Phys. Rev. E 68, 031602 (2003)] using a geometrically based classical density functional theory are in excellent agreement with the current simulation results for packing fractions in the range where Hadwiger's theorem is valid. However, above η ≈ 0.42, γ(R) shows significant deviations from the Hadwiger form indicating limitations to its use for high-density hard-sphere fluids. Using the results of this study together with Hadwiger's theorem allows one, in principle, to determine γ for any sufficiently smooth surface immersed in a hard-sphere fluid. PMID:23367884

  17. How Do You Like Your Equilibrium Selection Problems? Hard, or Very Hard?

    NASA Astrophysics Data System (ADS)

    Goldberg, Paul W.

    The PPAD-completeness of Nash equilibrium computation is taken as evidence that the problem is computationally hard in the worst case. This evidence is necessarily rather weak, in the sense that PPAD is only know to lie "between P and NP", and there is not a strong prospect of showing it to be as hard as NP. Of course, the problem of finding an equilibrium that has certain sought-after properties should be at least as hard as finding an unrestricted one, thus we have for example the NP-hardness of finding equilibria that are socially optimal (or indeed that have various efficiently checkable properties), the results of Gilboa and Zemel [6], and Conitzer and Sandholm [3]. In the talk I will give an overview of this topic, and a summary of recent progress showing that the equilibria that are found by the Lemke-Howson algorithm, as well as related homotopy methods, are PSPACE-complete to compute. Thus we show that there are no short cuts to the Lemke-Howson solutions, subject only to the hardness of PSPACE. I mention some open problems.

  18. Chronic toxicity of chloride to freshwater species: effects of hardness and implications for water quality guidelines.

    PubMed

    Elphick, James R F; Bergh, Kelli D; Bailey, Howard C

    2011-01-01

    Toxicity tests using nine freshwater species (Ceriodaphnia dubia, Daphnia magna, Oncorhynchus mykiss, Pimephales promelas, Lumbriculus variegatus, Tubifex tubifex, Chironomus dilutus, Hyallela azteca, and Brachionus calyciflorus) were conducted to evaluate their sensitivity to chloride. Acute-to-chronic ratios (ACRs) from these tests indicate the ACR of 7.59 employed by the United States Environmental Protection Agency (U.S. EPA) in deriving its water quality guideline for chloride may be conservative; a revised ACR of 3.50 is presented here. The endpoints used to calculate the ACR included 24-h to 96-h median lethal concentrations (LC50s) for acute tests, and 48-h to 54-d inhibition concentration (ICx) values for growth or reproduction for chronic exposures. Data from the present chronic toxicity tests, and other investigators, were used to propose a water quality guideline for long-term exposure to chloride using a species sensitivity distribution (SSD) approach. The 5th percentile from the SSD was calculated as 307 mg/L and proposed as the water quality guideline. Cladocerans were the most sensitive species in the dataset. Ceriodaphnia dubia was used to evaluate the relationship between water hardness and sensitivity to chloride. A strong relationship was observed and was used to establish a hardness-related equation to modify the proposed water quality guideline on the basis of water hardness, resulting in values ranging from 64 mg/L chloride at 10 mg/L hardness to 388 mg/L chloride at 160 mg/L hardness (as CaCO₃). These data suggest that current water quality guidelines for chloride may be overly conservative in water with moderate-to-high hardness, and may not be sufficiently protective under soft-water conditions. PMID:20872898

  19. Hardness of FeB{sub 4}: Density functional theory investigation

    SciTech Connect

    Zhang, Miao; Du, Yonghui; Gao, Lili; Lu, Mingchun; Lu, Cheng; Liu, Hanyu

    2014-05-07

    A recent experimental study reported the successful synthesis of an orthorhombic FeB{sub 4} with a high hardness of 62(5) GPa [H. Gou et al., Phys. Rev. Lett. 111, 157002 (2013)], which has reignited extensive interests on whether transition-metal borides compounds will become superhard materials. However, it is contradicted with some theoretical studies suggesting transition-metal boron compounds are unlikely to become superhard materials. Here, we examined structural and electronic properties of FeB{sub 4} using density functional theory. The electronic calculations show the good metallicity and covalent Fe–B bonding. Meanwhile, we extensively investigated stress-strain relations of FeB{sub 4} under various tensile and shear loading directions. The calculated weakest tensile and shear stresses are 40 GPa and 25 GPa, respectively. Further simulations (e.g., electron localization function and bond length along the weakest loading direction) on FeB{sub 4} show the weak Fe–B bonding is responsible for this low hardness. Moreover, these results are consistent with the value of Vickers hardness (11.7–32.3 GPa) by employing different empirical hardness models and below the superhardness threshold of 40 GPa. Our current results suggest FeB{sub 4} is a hard material and unlikely to become superhard (>40 GPa)

  20. The effect of heat treatment on the hardness and impact properties of medium carbon steel

    NASA Astrophysics Data System (ADS)

    Mazni Ismail, Noor; Khatif, Nurul Aida Amir; Aliff Kamil Awang Kecik, Mohamad; Hanafiah Shaharudin, Mohd Ali

    2016-02-01

    This paper covers the effect of heat treatment on the mechanical properties of medium carbon steel. The main objective of this project is to investigate the hardness and impact properties of medium carbon steel treated at different heat treatment processes. Three types of heat treatment were performed in this project which are annealing, quenching and tempering. During annealing process, the specimens were heated at 900°C and soaked for 1 hour in the furnace. The specimens were then quenched in a medium of water and open air, respectively. The treatment was followed by tempering processes which were done at 300°C, 450°C, and 600°C with a soaking time of 2 hours for each temperature. After the heat treatment process completed, Rockwell hardness test and Charpy impact test were performed. The results collected from the Rockwell hardness test and Charpy impact test on the samples after quenching and tempering were compared and analysed. The fractured surfaces of the samples were also been examined by using Scanning Electron Microscope. It was observed that different heat treatment processes gave different hardness value and impact property to the steel. The specimen with the highest hardness was found in samples quenched in water. Besides, the microstructure obtained after tempering provided a good combination of mechanical properties due to the process reduce brittleness by increasing ductility and toughness.

  1. Stochastic Gyroresonant Acceleration for Hard Electron Spectra of Blazars: Effect of Damping of Cascading Turbulence

    NASA Astrophysics Data System (ADS)

    Kakuwa, Jun

    2016-01-01

    Stochastic acceleration of nonthermal electrons is investigated in the context of hard photon spectra of blazars. It is well known that this acceleration mechanism can produce a hard electron spectrum of m≡ ∂ {ln}{n}{{e}}(γ )/∂ {ln}γ =2 with the high-energy cutoff, called an ultrarelativistic Maxwellian-like distribution, where {n}{{e}}(γ ) is an electron energy spectrum. We revisit the formation of this characteristic spectrum, considering a particular situation where the electrons are accelerated through gyroresonant interaction with magnetohydrodynamic wave turbulence driven by the turbulent cascade. By solving kinetic equations of the turbulent fields, electrons, and photons emitted via the synchrotron self-Compton (SSC) process, we demonstrate that in the non-test-particle treatment, the formation of a Maxwellian-like distribution is prevented by the damping effect on the turbulent fields due to the electron acceleration, at least unless an extreme parameter value is chosen. Instead, a softer electron spectrum with the index of m ≈ -1 is produced if the Kolmogorov-type cascade is assumed. The SSC spectrum that originates from the resultant softer electron spectrum is still hard, but somewhat softer and broader than the case of m = 2. This change of achievable hardness should be noted when this basic particle acceleration scenario is accurately tested with observations of hard photon spectra.

  2. Investigation of structural, dielectric, and magnetic properties of hard and soft mixed ferrite composites

    NASA Astrophysics Data System (ADS)

    Kotnala, R. K.; Ahmad, Shahab; Ahmed, Arham S.; Shah, Jyoti; Azam, Ameer

    2012-09-01

    Barium ferrite (hard ferrite) and manganese nickel zinc ferrite (soft ferrite) were successfully synthesized by citrate gel combustion technique. They were used to form the composites by mixing them properly in required compositions (x)BaFe12O19-(1-x)Mn0.2Ni0.4Zn0.4Fe2O4 (0 ≤ x ≤ 1). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to investigate the different structural and morphological parameters of pure and mixed ferrite composites. XRD and SEM results confirmed the coexistence of both phases in the composite material. Moreover, it has been observed that the composites were constituted by nanosized particles. Structure of pure soft ferrite was found to be cubic and that of pure hard ferrite was hexagonal. Dielectric constant (ɛ' and ɛ″) and dielectric loss (tan δ) were analyzed as a function of frequency and composition and the behaviour is explained on the basis of Maxwell-Wagner model. It was observed that the dielectric loss decreases with the increase of hard ferrite content in the composite material. Magnetic measurements suggest the exchange coupling between the magnetizations of soft and hard ferrite grains. It has been observed that the coercivity increases with the increase of the volume of the hard phase in the composite material after an optimal value.

  3. Superhard nanocomposite of dense polymorphs of boron nitride: Noncarbon material has reached diamond hardness

    NASA Astrophysics Data System (ADS)

    Dubrovinskaia, Natalia; Solozhenko, Vladimir L.; Miyajima, Nobuyoshi; Dmitriev, Vladimir; Kurakevych, Oleksandr O.; Dubrovinsky, Leonid

    2007-03-01

    The authors report a synthesis of unique superhard aggregated boron nitride nanocomposites (ABNNCs) showing the enhancement of hardness up to 100% in comparison with single crystal c-BN. Such a great hardness increase is due to the combination of the Hall-Petch and the quantum confinement effects. The decrease of the grain size down to 14nm and the simultaneous formation of the two dense BN phases with hexagonal and cubic structures within the grains at nano- and subnanolevel result in enormous mechanical property enhancement with maximum hardness of 85(5)GPa. Thus, ABNNC is the first non-carbon-based bulk material with the value of hard-ness approaching that of single crystal and polycrystalline diamond and aggregated diamond nanorods. ABNNC also has an unusually high fracture toughness for superhard materials (K1C=15MPam0.5) and wear resistance (WH=11; compare, for industrial polycrystalline diamond, WH=3-4), in combination with high thermal stability (above 1600K in air), making it an exceptional superabrasive.

  4. Hardness evaluation of prosthetic silicones containing opacifiers following chemical disinfection and accelerated aging.

    PubMed

    Goiato, Marcelo Coelho; Haddad, Marcela Fili; Santos, Daniela Micheline dos; Pesqueira, Aldiris Alves; Moreno, Amlia

    2010-01-01

    We evaluated the effects of disinfection and aging on the hardness of silicones containing opacifiers and intended for use in facial prosthetics. A total of 90 samples were produced using a cylindrical metal mold 3 mm in height and 30 mm in diameter. The samples were fabricated from Silastic MDX 4-4210 silicone in three groups: GI contained no opacifier, GII contained barium sulfate (Ba), and GIII contained titanium dioxide (Ti). The samples were disinfected using effervescent tablets (Ef), neutral soap (Ns), or 4% chlorhexidine (Cl) 3 times a week for 60 days. After this period the samples underwent 1,008 hours of accelerated aging. The hardness was measured using a durometer immediately following the disinfection period and after 252, 504, and 1,008 hours of aging. The data were statistically analyzed using 3-way ANOVA and the Tukey test (p < .05). The GIII group exhibited the greatest variation in hardness regardless of elapsed time. All groups displayed greater hardness after 1,008 hours of accelerated aging independent of disinfectant type. All of the hardness values were within the clinically acceptable range. PMID:20877967

  5. Effect of water hardness on the production and microbicidal efficacy of slightly acidic electrolyzed water.

    PubMed

    Forghani, Fereidoun; Park, Joong-Hyun; Oh, Deog-Hwan

    2015-06-01

    Slightly acidic electrolyzed water (SAEW) has been proved as an effective sanitizer against microorganisms attached to foods. However, its physical properties and inactivation efficacy are affected by several factors such as water hardness. Therefore, in this study the effect of water hardness on SAEW properties were studied. Pure cultures of foodborne bacteria were used in vitro and in vivo to evaluate the inactivation efficacy of the SAEWs produced. Results obtained showed water hardness to be an important factor in the production of SAEW. Low water hardness may result in the necessity of further optimization of production process. In this study the addition of 5% HCl and 2 M NaCl at 1.5 mL/min flow rate was found to be the best electrolyte concentration for the optimization of SAEW production from low hardness water (34 ± 2 mg/L). Furthermore, the results showed that pre-heating was a better approach compared to post-production heating of SAEW, resulting in higher ACC values and therefor better sanitization efficacy. PMID:25790988

  6. 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.

  7. Ultrafast switching of hard X-rays.

    PubMed

    Gaal, Peter; Schick, Daniel; Herzog, Marc; Bojahr, André; Shayduk, Roman; Goldshteyn, Jevgeni; Leitenberger, Wolfram; Vrejoiu, Ionela; Khakhulin, Dmitry; Wulff, Michael; Bargheer, Matias

    2014-03-01

    A new concept for shortening hard X-ray pulses emitted from a third-generation synchrotron source down to few picoseconds is presented. The device, called the PicoSwitch, exploits the dynamics of coherent acoustic phonons in a photo-excited thin film. A characterization of the structure demonstrates switching times of ≤ 5 ps and a peak reflectivity of ∼10(-3). The device is tested in a real synchrotron-based pump-probe experiment and reveals features of coherent phonon propagation in a second thin film sample, thus demonstrating the potential to significantly improve the temporal resolution at existing synchrotron facilities. PMID:24562559

  8. Nonvolatile Rad-Hard Holographic Memory

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Zhou, Han-Ying; Reyes, George; Dragoi, Danut; Hanna, Jay

    2001-01-01

    We are investigating a nonvolatile radiation-hardened (rad-hard) holographic memory technology. Recently, a compact holographic data storage (CHDS) breadboard utilizing an innovative electro-optic scanner has been built and demonstrated for high-speed holographic data storage and retrieval. The successful integration of this holographic memory breadboard has paved the way for follow-on radiation resistance test of the photorefractive (PR) crystal, Fe:LiNbO3. We have also started the investigation of using two-photon PR crystals that are doubly doped with atoms of iron group (Ti, Cr, Mn, Cu) and of rare-earth group (Nd, Tb) for nonvolatile holographic recordings.

  9. 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.

  10. Hard nonthermal emission from clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Bykov, A.

    We review current models of energetic particle acceleration and hard nonthermal emission from clusters of galaxies. The nonthermal phenomena in clusters are considered in the context of the hierarchical model of cosmic structure formation by accretion and merging of the dark matter (DM) substructures. Being the main gas-heating agent, large-scale shocks in the course of cluster aggregation and evolution accelerate energetic particles in collisionless turbulent plasma. Nonthermal emission of the energetic particles in clusters is a test to constrain the DM halos distribution and cosmological parameters. We discuss current status and perspective of INTEGRAL observations of clusters of galaxies.

  11. Hydrodynamics of self-propelled hard rods.

    PubMed

    Baskaran, Aparna; Marchetti, M Cristina

    2008-01-01

    Motivated by recent simulations and by experiments on aggregation of gliding bacteria, we study a model of the collective dynamics of self-propelled hard rods on a substrate in two dimensions. The rods have finite size, interact via excluded volume, and their dynamics is overdamped by the interaction with the substrate. Starting from a microscopic model with nonthermal noise sources, a continuum description of the system is derived. The hydrodynamic equations are then used to characterize the possible steady states of the systems and their stability as a function of the particles packing fraction and the speed of self-propulsion. PMID:18351889

  12. 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.

  13. Evaluation of degree of conversion and hardness of dental composites photo-activated with different light guide tips

    PubMed Central

    Galvo, Marlia Regalado; Caldas, Sergei Godeiro Fernandes Rabelo; Bagnato, Vanderlei Salvador; de Souza Rastelli, Alessandra Nara; de Andrade, Marcelo Ferrarezi

    2013-01-01

    Objective: The aim of this study was to evaluate the degree of conversion and hardness of different composite resins, photo-activated for 40 s with two different light guide tips, fiber optic and polymer. Methods: Five specimens were made for each group evaluated. The percentage of unreacted carbon double bonds (% C?C) was determined from the ratio of absorbance intensities of aliphatic C?C (peak at 1637 cm?1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm?1). The Vickers hardness measurements were performed in a universal testing machine. A 50 gf load was used and the indenter with a dwell time of 30 seconds. The degree of conversion and hardness mean values were analyzed separately by ANOVA and Tukeys test, with a significance level set at 5%. Results: The mean values of degree of conversion for the polymer and fiber optic light guide tip were statistically different (P<.001). The hardness mean values were statistically different among the light guide tips (P<.001), but also there was difference between top and bottom surfaces (P<.001). Conclusions: The results showed that the resins photo-activated with the fiber optic light guide tip promoted higher values for degree of conversion and hardness. PMID:23407620

  14. The Relationship Between the Accumulated Number of Role Transitions and Hard Drug Use Among Hispanic Emerging Adults

    PubMed Central

    Allem, Jon-Patrick; Soto, Daniel; Baezconde-Garbanati, Lourdes; Unger, Jennifer

    2014-01-01

    Emerging adults (ages 18 to 25) who experience multiple role transitions in a short period of time may engage in hard drug use as a maladaptive coping strategy to avoid negative emotions from stress. Given the collectivistic values Hispanics encounter growing up, they may experience additional role transitions due to their group oriented cultural paradigm. This study examined whether those who experience many role transitions are at greater risk for hard drug use compared to those who experience few transitions among Hispanic emerging adults. Participants completed surveys indicating their hard drug use in emerging adulthood, role transitions in the past year of emerging adulthood, age, gender, and hard drug use in high school. Simulation analyses indicated that an increase in the number of role transitions, from 0 to 13, was associated with a 14% (95% CI, 4 to 29) higher probability of hard drug use. Specific role transitions were found to be associated with hard drug use, such as starting to date or experiencing a breakup. Intervention/prevention programs may benefit from acknowledging individual reactions to transitions in emerging adulthood, as these processes may be catalysts for personal growth where identities are consolidated, and decisions regarding hard drug use are formed. PMID:25715073

  15. Manifold-valued Dirichlet Processes

    PubMed Central

    Kim, Hyunwoo J.; Xu, Jia; Vemuri, Baba C.; Singh, Vikas

    2016-01-01

    Statistical models for manifold-valued data permit capturing the intrinsic nature of the curved spaces in which the data lie and have been a topic of research for several decades. Typically, these formulations use geodesic curves and distances defined locally for most cases — this makes it hard to design parametric models globally on smooth manifolds. Thus, most (manifold specific) parametric models available today assume that the data lie in a small neighborhood on the manifold. To address this ‘locality’ problem, we propose a novel nonparametric model which unifies multivariate general linear models (MGLMs) using multiple tangent spaces. Our framework generalizes existing work on (both Euclidean and non-Euclidean) general linear models providing a recipe to globally extend the locally-defined parametric models (using a mixture of local models). By grouping observations into sub-populations at multiple tangent spaces, our method provides insights into the hidden structure (geodesic relationships) in the data. This yields a framework to group observations and discover geodesic relationships between covariates X and manifold-valued responses Y, which we call Dirichlet process mixtures of multivariate general linear models (DP-MGLM) on Riemannian manifolds. Finally, we present proof of concept experiments to validate our model. PMID:26973982

  16. Statistical Physics of Hard Optimization Problems

    NASA Astrophysics Data System (ADS)

    Zdeborová, Lenka

    2008-06-01

    Optimization is fundamental in many areas of science, from computer science and information theory to engineering and statistical physics, as well as to biology or social sciences. It typically involves a large number of variables and a cost function depending on these variables. Optimization problems in the NP-complete class are particularly difficult, it is believed that the number of operations required to minimize the cost function is in the most difficult cases exponential in the system size. However, even in an NP-complete problem the practically arising instances might, in fact, be easy to solve. The principal question we address in this thesis is: How to recognize if an NP-complete constraint satisfaction problem is typically hard and what are the main reasons for this? We adopt approaches from the statistical physics of disordered systems, in particular the cavity method developed originally to describe glassy systems. We describe new properties of the space of solutions in two of the most studied constraint satisfaction problems - random satisfiability and random graph coloring. We suggest a relation between the existence of the so-called frozen variables and the algorithmic hardness of a problem. Based on these insights, we introduce a new class of problems which we named "locked" constraint satisfaction, where the statistical description is easily solvable, but from the algorithmic point of view they are even more challenging than the canonical satisfiability.

  17. Flux monitor diode radiation hardness testing

    NASA Astrophysics Data System (ADS)

    Lombardi, M. L.; Favalli, A.; Goda, J. M.; Ianakiev, K. D.; Moss, C. E.

    2011-10-01

    A flux monitor diode is being explored as an option for measurement of the output of an X-ray tube that is used for active transmission measurements on a pipe containing UF 6 gas. The measured flux can be used to correct for any instabilities in the X-ray tube or the high voltage power supply. For this measurement, we are using a silicon junction p-n photodiode, model AXUV100GX, developed by International Radiation Detectors, Inc. (IRD, Inc.). This diode has a silicon thickness of 104 μ and a thin (3-7 nm) silicon dioxide junction passivating, protective entrance window. These diodes have been extensively tested for radiation hardness in the UV range. However, we intend to operate mainly in the 10-40 keV X-ray region. We are performing radiation hardness testing over this energy range, with the energy spectrum that would pass through the diode during normal operation. A long-term measurement was performed at a high flux, which simulated over 80 years of operation. No significant degradation was seen over this time. Fluctuations were found to be within the 0.1% operationally acceptable error range. After irradiation, an I- V characterization showed a temporary irradiation effect which decayed over time. This effect is small because we operate the diode without external bias.

  18. The rheology of adhesive hard sphere dispersions

    NASA Astrophysics Data System (ADS)

    Woutersen, A. T. J. M.; de Kruif, C. G.

    1991-04-01

    The influence of an attractive interparticle potential on the rheology of a sterically stabilized silica dispersion was investigated. Using a marginal solvent, there was an effective attraction between the particles which depended on the temperature. Three experiments in which different properties of the dispersion were probed showed that a square well model can be used to describe the temperature dependence of the pair potential. The turbidity of a dilute dispersion was measured as a function of the volume fraction and the temperature. Using dynamic light scattering techniques, the effect of the strength of the interparticle attraction on the diffusion coefficient was investigated. Furthermore, the steady shear viscosity was measured as a function of the volume fraction and the temperature. A microscopic theory for the low shear viscosity of a semidilute dispersion of adhesive hard spheres was successfully used to determine the interaction parameters. Viscosity measurement on dense suspensions showed that while the system is still in the one-phase state, temporal aggregates are formed by the interparticle forces which are disrupted by both shear and Brownian motion of the particles. The shear thinning behavior of a concentrated dispersion of adhesive hard spheres scales in a dimensionless shear stress. This group is the ratio of the forces, arising from the shear and the interparticle potential.

  19. Solving the hard problem of Bertrand's paradox

    SciTech Connect

    Aerts, Diederik; Sassoli de Bianchi, Massimiliano

    2014-08-15

    Bertrand's paradox is a famous problem of probability theory, pointing to a possible inconsistency in Laplace's principle of insufficient reason. In this article, we show that Bertrand's paradox contains two different problems: an “easy” problem and a “hard” problem. The easy problem can be solved by formulating Bertrand's question in sufficiently precise terms, so allowing for a non-ambiguous modelization of the entity subjected to the randomization. We then show that once the easy problem is settled, also the hard problem becomes solvable, provided Laplace's principle of insufficient reason is applied not to the outcomes of the experiment, but to the different possible “ways of selecting” an interaction between the entity under investigation and that producing the randomization. This consists in evaluating a huge average over all possible “ways of selecting” an interaction, which we call a universal average. Following a strategy similar to that used in the definition of the Wiener measure, we calculate such universal average and therefore solve the hard problem of Bertrand's paradox. The link between Bertrand's problem of probability theory and the measurement problem of quantum mechanics is also briefly discussed.

  20. Addendum to: Uniform Elongation and the Stress-Strain Flow Curve of Steels Calculated from Hardness Using Empirical Correlations

    NASA Astrophysics Data System (ADS)

    Pavlina, Erik J.; Van Tyne, Chester J.

    2015-11-01

    The original study by Pavlina and Van Tyne developed correlations of hardness and strength (yield and ultimate tensile strength) (Pavlina and Van Tyne in J Mater Eng Perform 17:888-893, 2008). As an extension to this original work, a later paper developed an empirical relationship between the hardness and uniform elongation of non-austenitic hypoeutectoid steels (Pavlina and Van Tyne in J Mater Eng Perform 23:2247-2254, 2014). The empirical hardness-elongation relationship was combined with the correlations in the original study to show how a single hardness test could predict a reasonable stress-strain flow curve for a steel. The current study provides tables of parameter values for four different hardening models, based on the hardness correlations that were developed in the two previous studies. The models are the two-parameter Holloman model and the three-parameter Ludwig, Swift, and Voce models. Although they are empirical, these parameters allow the flow behavior of steels to be reasonably well characterized, based on a single hardness value. These tables should only be used when limited material is available, or when insufficient data are available for the specific grade of steel needing characterization.

  1. Evaluation of Vickers hardness and depth of cure of six composite resins photo-activated with different polymerization modes

    PubMed Central

    Poggio, C; Lombardini, M; Gaviati, S; Chiesa, M

    2012-01-01

    Aim: The current in vitro study evaluated Vickers hardness (VK) and depth of cure (hardness ratio) of six resin composites, polymerized with a light-emitting diode (LED) curing unit by different polymerization modes: Standard 20 s, Standard 40 s, Soft-start 40 s. Materials and Methods: Six resin composites were selected for the present study: three microhybrid (Esthet.X HD, Amaris, Filtek Silorane), two nanohybrid (Grandio, Ceram.X mono) and one nanofilled (Filtek Supreme XT). The VK of the surface was determined with a microhardness tester using a Vickers diamond indenter and a 200 g load applied for 15 seconds. The mean VK and hardness ratio of the specimens were calculated using the formula: hardness ratio = VK of bottom surface / VK of top surface. Results: For all the materials tested and with all the polymerization modes, hardness ratio was higher than the minimum value indicated in literature in order to consider the bottom surface as adequately cured (0.80). Curing time did not affect hardness ratio values for Filtek Silorane, Grandio and Filtek Supreme XT. Conclusion: The effectiveness of cure at the top and bottom surface was not affected by Soft-start polymerization mode. PMID:22876009

  2. Debating Propositions of Value.

    ERIC Educational Resources Information Center

    Matlon, Ronald J.

    1978-01-01

    Advances a rationale for debating propositions of value in interscholastic contests. Considers implications for burden of proof, presumption, and the location of issues in value propositions, and proposes a preliminary system for the analysis of value propositions. (JMF)

  3. Arguing Value Propositions.

    ERIC Educational Resources Information Center

    Warnick, Barbara

    1981-01-01

    Describes the stages of value analysis. Concludes that the practice of debating value resolutions may lead to a refinement and expansion of argumentation theory and can provide students with an opportunity to clarify their own values. (PD)

  4. Hard X-ray identification of η Carinae and steadiness close to periastron

    NASA Astrophysics Data System (ADS)

    Leyder, J.-C.; Walter, R.; Rauw, G.

    2010-12-01

    Context. The colliding-wind binary η Carinae exhibits soft X-ray thermal emission that varies strongly around the periastron passage. It has been found to have non-thermal emission, thanks to its detection in hard X-rays using INTEGRAL and Suzaku, and also in γ-rays with AGILE and Fermi. Aims: This paper attempts to definitively identify η Carinae as the source of the hard X-ray emission, to examine how changes in the 2-10 keV band influence changes in the hard X-ray band, and to understand more clearly the mechanisms producing the non-thermal emission using new INTEGRAL observations obtained close to periastron passage. Methods: To strengthen the identification of η Carinae with the hard X-ray source, a long Chandra observation encompassing the INTEGRAL/ISGRI error circle was analysed, and all other soft X-ray sources (including the outer shell of η Carinae itself) were discarded as likely counter-parts. To expand the knowledge of the physical processes governing the X-ray lightcurve, new hard X-ray images of η Carinae were studied close to periastron, and compared to previous observations far from periastron. Results: The INTEGRAL component, when represented by a power law (with a photon index Γ of 1.8), would produce more emission in the Chandra band than observed from any point source in the ISGRI error circle apart from η Carinae, as long as the hydrogen column density to the ISGRI source is lower than NH ≲ 1024 cm-2. Sources with such a high absorption are very rare, thus the hard X-ray emission is very likely to be associated with η Carinae. The eventual contribution of the outer shell to the non-thermal component also remains fairly limited. Close to periastron passage, a 3-σ detection is achieved for the hard X-ray emission of η Carinae, with a flux similar to the average value far from periastron. Conclusions: Assuming a single absorption component for both the thermal and non-thermal sources, this 3-σ detection can be explained with a hydrogen column density that does not exceed NH ≲ 6 × 1023 cm-2 without resorting to an intrinsic increase in the hard X-ray emission. The energy injected in hard X-rays (averaged over a month timescale) appears to be rather constant at least as close as a few stellar radii, well within the acceleration region of the wind.

  5. Observational Aspects of Hard X-ray Polarimetry

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanmoy

    2016-04-01

    Sensitive polarization measurements in X-ray may address a wealth of as- trophysical phenomena, which so far remain beyond our understanding through available X-ray spectroscopic, imaging, and timing studies. Though scientific potential of X-ray polarimetry was realized long ago, there has not been any significant advancement in this field for the last four decades since the birth of X-ray astronomy. The only successful polarization measurement in X-rays dates back to 1976, when a Bragg polarimeter onboard OSO-8 measured polarization of Crab nebula. Primary reason behind the lack in progress is its extreme photon hungry nature, which results in poor sensitivity of the polarimeters. Recently, in the last decade or so, with the advancement in detection technology, X-ray polarimetry may see a significant progress in near future, especially in soft X-rays with the invention of photoelectron tracking polarimeters. Though photoelectric polarimeters are expected to provide sensitive polarization measurements of celestial X-ray sources, they are sensitive only in soft X-rays, where the radiation from the sources is dominated by thermal radiation and therefore expected to be less polarized. On the other hand, in hard X-rays, sources are expected to be highly polarized due to the dominance of nonthermal emission over its thermal counterpart. Moreover, polarization measurements in hard X-rays promises to address few interesting scientific issues regarding geometry of corona for black hole sources, emission mechanism responsible for the higher energy peak in the blazars, accretion geometry close to the magnetic poles in accreting neutron star systems and acceleration mechanism in solar flares. Compton polarimeters provide better sensitivity than photoelectric polarimeters in hard X-rays with a broad energy band of operation. Recently, with the development of hard X-ray focusing optics e.g. NuSTAR, Astro-H, it is now possible to conceive Compton polarimeters at the focal plane of such hard X-ray telescopes, which may provide sensitive polarization measurements due to flux concentration in hard X-rays with a very low background. On the other hand, such a configuration ensures implementation of an optimized geometry close to an ideal one for the Compton polarimeters. In this context, we initiated the development of a focal plane Compton polarimeter, consisting of a plastic scatterer surrounded by a cylindrical array of CsI(Tl) scintillators. Geant-4 simulations of the planned configuration estimates 1% MDP for a 100 mCrab source in 1 million seconds of exposure. Sensitivity of the instrument is found to be critically dependent on the lower energy detection limit of the plastic scatterer; lower the threshold, better is the sensitivity. In the actual experiment, the plastic is readout by a photomultiplier tube procured from Saint-Gobain. We carried out extensive experiments to characterize the plastic especially for lower energy depositions. The CsI(Tl) scintillators are readout by Si photomultipliers (SiPM). SiPMs are small in size and robust and therefore provide the compactness necessary for the designing of focal plane detectors. Each of the CsI(Tl)-SiPM systems was characterized precisely to estimate their energy threshold and detection probability along the length of the scintillators away from SiPM. Finally, we integrated the Compton polarimeter and tested its response to polarized and unpolarized radiation and compared the experimental results with Geant-4 simulation. Despite the growing realization of the scientific values of X-ray polarimetry and the efforts in developing sensitive X-ray polarimeters, there has not been a single dedicated X-ray polarimetry mission planned in near future. In this scenario, it is equally important to attempt polarization measurements from the existing or planned instruments which are not meant for X-ray polarization measurements but could be sensitive to it. There have been several attempts in past in retrieving polarization information from few of such spectroscopic instruments like RHESSI, INTEGRAL-IBIS, INTEGRAL-SPI. Cadmium Zinc Telluride Imager (CZTI) onboard Astrosat, India's first astronomical mission, is one of such instruments which is expected to provide sensitive polarization measurements for bright X-ray sources. CZTI consists of 64 CZT detector modules, each of which is 5 mm thick and 4 cm × 4 cm in size. Each CZT module is subdivided into 256 pixels with pixel pitch of 2.5 mm. Due to its pixelation nature and significant Compton scattering efficiency at energies beyond 100 keV, CZTI can work as a sensitive Compton polarimeter in hard X-rays. Detailed Geant-4 simulations and polarization experiments with the flight configuration of CZTI show that CZTI will have significant polarization measurement capability for bright sources in hard X-rays. CZTI is primarily a spectroscopic instrument with coded mask imaging. To properly utilize the spectroscopic capabilities of CZT detectors, it is important to generate accurate response matrix for CZTI, which in turn requires precise modelling of the CZT lines shapes for monoenergetic X-ray interaction. CZT detectors show an extended lower energy tail of an otherwise Gaussian line shape due to low mobility and lifetime of the charge carriers. On the other hand, interpixel charge sharing may also contribute to the lower energy tail making the line shape more complicated. We have developed a model to predict the line shapes from CZTI modules taking into account the mobility and lifetime of the charge carriers and charge sharing fractions. The model predicts the line shape quite well and can be used to generate pixel-wise response matrix for CZTI.

  6. 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. PMID:26620934

  7. 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…

  8. 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

  9. Influence of Nitrogen Flow Rates on the Structure, Hardness, and Electrical Resistivity of HfN Coatings by DC Sputtering

    NASA Astrophysics Data System (ADS)

    García-González, Leandro; Zamora-Peredo, Luis; Flores-Ramírez, Nelly; Garnica-Romo, María Guadalupe; Hernández-Torres, Julián

    2015-04-01

    HfN hard coatings on Corning glass substrates were obtained using DC sputtering. A power of 200 W was used keeping the flow rate of argon at 10 sccm and varying the nitrogen flow rates at 2.5, 3.5, 5.0, and 7.5 sccm to analyze differences in the hardness and electrical resistivity values, explaining variations in relation to structural changes. To achieve this, the Vickers microhardness test, x-ray diffraction, Raman, atomic force microscopy, and high resistivity measurements were used. At 2.5 sccm, the hardness value was shown to reach a maximum value of 20 GPa, and a minimum electrical resistivity of 6.5 × 108 µΩcm. Furthermore, as the flow is increased, the hardness values gradually decrease (until a value of 8 GPa is reached), the fracture toughness increase (until a value of 0.3 MPa√m is reached), and the electrical resistivity reaches its maximum at 1.52 × 1012 μΩcm. These variations are attributed to the evolution that the HfN phase progressively undergoes from a crystal orientation at (111) to an amorphous phase. In addition, the presence of tensile stresses, which tend to favor electrical resistivity, was identified. The average RMS roughness increased from 3.76 to 10.69 nm as the nitrogen flow was increased. Finally, the Raman spectroscopy confirmed the presence of the HfN phase.

  10. The entropies of the hard sphere alkali halide crystals

    NASA Astrophysics Data System (ADS)

    Cox, John W.; Beyerlein, Adolph L.

    1982-08-01

    An asymptotic expansion for the entropy of hard-sphere alkali halide crystals with N small and large particle pairs is obtained: SN/NkB ???13 ln(?ls2e)/(?l?s) +3 ln(?1/3-1)+3 ln ?-C-D?-E?2+???, where kB is the Boltzman constant, e is the natural number, ? is the ratio of the system volume to its high compression limiting volume, ?l and ?s are the mean thermal de Broglie wavelengths [?=(h2/2?mkBT)1/2, m being the mass] of the large and small particles, respectively, ?ls is the hard-sphere collision diameter of nearest neighbor large and small particles; C, D, E, etc. are well-defined parameters dependent on the small to large particle radius ratio and the lattice structure, and ?=[(?1/3-1)+(1-?ls/?ls')], where ?ls' is the average distance between nearest neighbor large and small particles in the high compression limit. If the small to large particle radius ratio is less than ?2-1 for the ''NaCl'' lattice and less than ?3-1 for the ''CsCl'' lattice ?lsvalues at temperatures approaching the melting point which is consistent with the contention that the hard sphere contribution to the entropy dominates other contributions at high temperatures. The predicted difference between the entropies of the two alkali halide lattices is also consistent with the experimental data at higher temperatures.

  11. Evolutionary algorithm based structure search for hard ruthenium carbides

    NASA Astrophysics Data System (ADS)

    Harikrishnan, G.; Ajith, K. M.; Chandra, Sharat; Valsakumar, M. C.

    2015-12-01

    An exhaustive structure search employing evolutionary algorithm and density functional theory has been carried out for ruthenium carbides, for the three stoichiometries Ru1C1, Ru2C1 and Ru3C1, yielding five lowest energy structures. These include the structures from the two reported syntheses of ruthenium carbides. Their emergence in the present structure search in stoichiometries, unlike the previously reported ones, is plausible in the light of the high temperature required for their synthesis. The mechanical stability and ductile character of all these systems are established by their elastic constants, and the dynamical stability of three of them by the phonon data. Rhombohedral structure ≤ft(R\\bar{3}m\\right) is found to be energetically the most stable one in Ru1C1 stoichiometry and hexagonal structure ≤ft( P\\bar{6}m2\\right) , the most stable in Ru3C1 stoichiometry. RuC-Zinc blende system is a semiconductor with a band gap of 0.618 eV while the other two stable systems are metallic. Employing a semi-empirical model based on the bond strength, the hardness of RuC-Zinc blende is found to be a significantly large value of ~37 GPa while a fairly large value of ~21GPa is obtained for the RuC-Rhombohedral system. The positive formation energies of these systems show that high temperature and possibly high pressure are necessary for their synthesis.

  12. A multi-step system for screening and localization of hard exudates in retinal images

    NASA Astrophysics Data System (ADS)

    Bopardikar, Ajit S.; Bhola, Vishal; Raghavendra, B. S.; Narayanan, Rangavittal

    2012-03-01

    The number of people being affected by Diabetes mellitus worldwide is increasing at an alarming rate. Monitoring of the diabetic condition and its effects on the human body are therefore of great importance. Of particular interest is diabetic retinopathy (DR) which is a result of prolonged, unchecked diabetes and affects the visual system. DR is a leading cause of blindness throughout the world. At any point of time 25 - 44% of people with diabetes are afflicted by DR. Automation of the screening and monitoring process for DR is therefore essential for efficient utilization of healthcare resources and optimizing treatment of the affected individuals. Such automation would use retinal images and detect the presence of specific artifacts such as hard exudates, hemorrhages and soft exudates (that may appear in the image) to gauge the severity of DR. In this paper, we focus on the detection of hard exudates. We propose a two step system that consists of a screening step that classifies retinal images as normal or abnormal based on the presence of hard exudates and a detection stage that localizes these artifacts in an abnormal retinal image. The proposed screening step automatically detects the presence of hard exudates with a high sensitivity and positive predictive value (PPV ). The detection/localization step uses a k-means based clustering approach to localize hard exudates in the retinal image. Suitable feature vectors are chosen based on their ability to isolate hard exudates while minimizing false detections. The algorithm was tested on a benchmark dataset (DIARETDB1) and was seen to provide a superior performance compared to existing methods. The two-step process described in this paper can be embedded in a tele-ophthalmology system to aid with speedy detection and diagnosis of the severity of DR.

  13. Electronic and bonding analysis of hardness in pyrite-type transition-metal pernitrides

    NASA Astrophysics Data System (ADS)

    Liu, Z. T. Y.; Gall, D.; Khare, S. V.

    2014-10-01

    Most commonly known hard transition-metal nitrides crystallize in rocksalt structure (B1). The discovery of ultraincompressible pyrite-type PtN2 10 years ago has raised a question about the cause of its exceptional mechanical properties. We answer this question by a systematic computational analysis of the pyrite-type PtN2 and other transition-metal pernitrides (MN2) with density functional theory. Apart from PtN2, the three hardest phases are found among them in the 3d transition-metal period. They are MnN2, CoN2, and NiN2, with computed Vickers hardness (HV) values of 19.9 GPa, 16.5 GPa, and 15.7 GPa, respectively. Harder than all of these is PtN2, with a HV of 23.5 GPa. We found the following trends and correlations that explain the origin of hardness in these pernitrides. (a) Charge transfer from M to N controls the length of the N-N bond, resulting in a correlation with bulk modulus, dominantly by providing Coulomb repulsion between the pairing N atoms. (b) Elastic constant C44, an indicator of mechanical stability and hardness is correlated with total density of states at EF, an indicator of metallicity. (c) Often cited monotonic variation of HV and Pugh's ratio with valence electron concentration found in rocksalt-type early transition-metal nitrides is not evident in this structure. (d) The change in M-M bond strength under a shearing strain indicated by crystal orbital Hamilton population is predictive of hardness. This is a direct connection between a specific bond and shear related mechanical properties. This panoptic view involving ionicity, metallicity, and covalency is essential to obtain a clear microscopic understanding of hardness.

  14. Five Values of Giftedness

    ERIC Educational Resources Information Center

    Besjes-de Bock, Karin M.; de Ruyter, Doret J.

    2011-01-01

    This article describes five values attributed to giftedness. The ascription of values to this phenomenon resembles values attached to gifts in gift-giving processes. Whereas gift-giving often includes expectations of reciprocity, each gift possesses a numerical, utility, social, personal, and intrinsic value. Developmental models of giftedness and…

  15. Values as Defenses

    ERIC Educational Resources Information Center

    Hultman, Kenneth E.

    1976-01-01

    The author outlines a cognitive approach for explaining how and why people use values as defenses. He examines the relationship between defensive values and irrational beliefs, suggests a number of criteria for diagnosing the presence of defensive values, and proposes some strategies for dealing with defensive values in counseling. (Author)

  16. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  17. 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.

  18. Hard scattering phenomena from RHIC to LHC

    SciTech Connect

    Rak, Jan

    2011-05-23

    In the Relativistic Heavy Ion Collider era the high-p{sub T} particle emerging from hard scattering became an important tool of exploration of excited nuclear medium formed in ultra-relativistic heavy ion collisions. Discovery of anomalous suppression of high-p{sub T} particle yield [1] together with an observation of disappearance of back-to-back hadron correlation in central Au+Au collisions in 2002 [2] were the key results interpreted as a manifestation of the deconfined QCD medium in heavy ion collisions. Analysis of the high-p{sub T} particle and jet production is already a standard experimental technique providing a test bench for pQCD description of the point-like constituent scattering in p+p collisions and sensitive probes of the excited nuclear medium in A+A collisions.

  19. Hard turning micro-machine tool

    DOEpatents

    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.

  20. Pathosis of the hard and soft palate.

    PubMed

    Nelson, J F; Tsaknis, P J

    1978-04-01

    In this article a few of the more recently emphasized and pertinent conditions that may affect the hard and soft palate have been discussed. The purpose of the article is not to present in all-inclusive classification of lesions occurring the palate. Disease of the palate may be local in nature or may reflect a systemic condition. Dentists must be conscious of the palate as the site of many possible pathoses. The prosthodontist in particular must observe and carefully evaluate the palate and insure its good health before he can prescribe a prosthesis to cover it. Dentistry provides a health service which affects the entire human organism and not just the oral cavity. Therefore an understanding of the varied nature of pathosis as it relates to the oral cavity, and especially the palate, is essential. Continuous surveillance of the palatal regions insures that the dentist's obligation to detect oral abnormalities in patients is in large measure fulfilled. PMID:205648

  1. 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.

  2. Radiation-hard optical link for SLHC

    NASA Astrophysics Data System (ADS)

    Gan, K. K.; Abi, B.; Fernando, W.; Kagan, H. P.; Kass, R. D.; Law, A.; Lebbai, M. R. M.; Rau, A.; Rizardinova, F.; Skubic, P. L.; Smith, D. S.

    2008-05-01

    We study the feasibility of fabricating an optical link for the SLHC ATLAS silicon tracker based on the current pixel optical link architecture. The electrical signals between the current pixel modules and the optical modules are transmitted via micro-twisted cables. The optical signals between the optical modules and the data acquisition system are transmitted via rad-hard SIMM fibres spliced to rad-tolerant GRIN fibres. The link has several nice features. We have measured the bandwidths of the micro twisted-pair cables to be bsim 1 Gb/s and the fusion spliced fibre ribbon to be bsim 2 Gb/s. We have irradiated PIN and VCSEL arrays with 24 GeV protons and find the arrays survive to the SLHC dosage. We have also demonstrated the feasibility of fabricating a novel opto-pack for housing VCSEL and PIN arrays with BeO as the substrate.

  3. Radiation-hard optical link for SLHC

    NASA Astrophysics Data System (ADS)

    Gan, K. K.; Fernando, W.; Kagan, H.; Kass, R.; Law, A.; Smith, S.; Lebbi, M. R. M.; Skubic, P. L.

    2008-10-01

    We study the feasibility of fabricating an optical link for the SLHC ATLAS silicon tracker based on the current pixel optical link architecture. The electrical signals between the current pixel modules and the optical modules are transmitted via micro-twisted cables. The optical signals between the optical modules and the data acquisition system are transmitted via radiation-hard/low-bandwidth SIMM fibres fusion spliced to radiation-tolerant/medium-bandwidth GRIN fibres. The link has several nice features. We have measured the bandwidths of the micro-twisted-pair cables to be ˜1 Gb/s and the fusion spliced fibre ribbon to be ˜2 Gb/s. We have irradiated PIN and VCSEL arrays with 24 GeV protons and find the arrays can operate up to the SLHC dosage. We have also demonstrated the feasibility of fabricating a novel opto-pack for housing VCSEL and PIN arrays with BeO as the substrate.

  4. Templated crystallisation: soft phases controlling hard materials

    NASA Astrophysics Data System (ADS)

    Fairclough, J. Patrick A.; Turner, Simon C.; Bras, Wim; Mai, Shao-Min; Booth, Colin; Ryan, Anthony J.

    2000-03-01

    Throughout nature, the structure of hard materials eg bone, is controlled by a soft template. We have examined crystallisation in shear oriented block copolymers, where a soft phase of microphase separated melt controls the preferred direction of crystallisation. In lamella phases, the comparison is simple and direct over a range of molecular weight and domain sizes. For hexagonal arranged cylindrical systems and for cubic gryoid structures, the choice of preferred directions is limited. We have used real time SAXS & WAXS to monitor the structure formation upon crystallisation paying particular attention to the orientation of the crystal stems with respect to the lamellar interfaces. A model based on chain stretching in the melt will be proposed to account for the observed orientation.

  5. 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.

  6. 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

    Development of flexible thin film systems for biomedical, homeland security and environmental sensing applications has increased dramatically in recent years [1,2,3,4]. These systems typically combine traditional semiconductor technology with new flexible substrates, allowing for both the high electron mobility of semiconductors and the flexibility of polymers. The devices have the ability to be easily integrated into components and show promise for advanced design concepts, ranging from innovative microelectronics to MEMS and NEMS devices. These devices often contain layers of thin polymer, ceramic and metallic films where differing properties can lead to large residual stresses [5]. As long as the films remain substrate-bonded, they may deform far beyond their freestanding counterpart. Once debonded, substrate constraint disappears leading to film failure where compressive stresses can lead to wrinkling, delamination, and buckling [6,7,8] while tensile stresses can lead to film fracture and decohesion [9,10,11]. In all cases, performance depends on film adhesion. Experimentally it is difficult to measure adhesion. It is often studied using tape [12], pull off [13,14,15], and peel tests [16,17]. More recent techniques for measuring adhesion include scratch testing [18,19,20,21], four point bending [22,23,24], indentation [25,26,27], spontaneous blisters [28,29] and stressed overlayers [7,26,30,31,32,33]. Nevertheless, sample design and test techniques must be tailored for each system. There is a large body of elastic thin film fracture and elastic contact mechanics solutions for elastic films on rigid substrates in the published literature [5,7,34,35,36]. More recent work has extended these solutions to films on compliant substrates and show that increasing compliance markedly changes fracture energies compared with rigid elastic solution results [37,38]. However, the introduction of inelastic substrate response significantly complicates the problem [10,39,40]. As 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.

  7. Non-hard sphere thermodynamic perturbation theory

    NASA Astrophysics Data System (ADS)

    Zhou, Shiqi

    2011-08-01

    A non-hard sphere (HS) perturbation scheme, recently advanced by the present author, is elaborated for several technical matters, which are key mathematical details for implementation of the non-HS perturbation scheme in a coupling parameter expansion (CPE) thermodynamic perturbation framework. NVT-Monte Carlo simulation is carried out for a generalized Lennard-Jones (LJ) 2n-n potential to obtain routine thermodynamic quantities such as excess internal energy, pressure, excess chemical potential, excess Helmholtz free energy, and excess constant volume heat capacity. Then, these new simulation data, and available simulation data in literatures about a hard core attractive Yukawa fluid and a Sutherland fluid, are used to test the non-HS CPE 3rd-order thermodynamic perturbation theory (TPT) and give a comparison between the non-HS CPE 3rd-order TPT and other theoretical approaches. It is indicated that the non-HS CPE 3rd-order TPT is superior to other traditional TPT such as van der Waals/HS (vdW/HS), perturbation theory 2 (PT2)/HS, and vdW/Yukawa (vdW/Y) theory or analytical equation of state such as mean spherical approximation (MSA)-equation of state and is at least comparable to several currently the most accurate Ornstein-Zernike integral equation theories. It is discovered that three technical issues, i.e., opening up new bridge function approximation for the reference potential, choosing proper reference potential, and/or using proper thermodynamic route for calculation of fex - ref, chiefly decide the quality of the non-HS CPE TPT. Considering that the non-HS perturbation scheme applies for a wide variety of model fluids, and its implementation in the CPE thermodynamic perturbation framework is amenable to high-order truncation, the non-HS CPE 3rd-order or higher order TPT will be more promising once the above-mentioned three technological advances are established.

  8. 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.

  9. 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

  10. 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. PMID:16250629

  11. Effects of food-simulating liquids on surface properties of giomer restoratives.

    PubMed

    Kooi, T J M; Tan, Q Z; Yap, A U J; Guo, W; Tay, K J; Soh, M S

    2012-01-01

    This study examined the effects of food-simulating liquid (FSL) on the hardness and roughness of giomer restoratives based on pre-reacted glass ionomer (PRG) technology. The materials investigated included a regular (Beautifil II [BT]) and a recently introduced injectable (Beautifil Flow Plus F00 [BF]) hybrid PRG composite. A direct hybrid composite (Filtek Z250 [ZT]) and an indirect hybrid composite (Ceramage [CM]) were used for comparison. The materials were placed into customized square molds (5 mm 5 mm 2.5 mm), covered with Mylar strips, and cured according to manufacturers' instructions. The materials were then conditioned in air (control), distilled water, 50% ethanol solution, and 0.02 N citric acid at 37C for seven days. Specimens (n=6) were then subjected to hardness testing (Knoop) and surface profilometry. Data were analyzed using one-way analysis of variance and post hoc Scheffe test (p<0.05). Mean Knoop hardness values for the control group (air) ranged from 53.4 3.4 (BF) to 89.5 5.2 (ZT), while mean surface roughness values values ranged from 0.014 0.002 (ZT) to 0.032 0.001 (BT). All materials were significantly softened by FSL. The degree of softening by the different FSLs was material dependent. The hardness of giomers was most affected by citric acid and ethanol. The smoothest surface was generally observed with the control group. Giomer restoratives were significantly roughened by citric acid. PMID:22663197

  12. Influence of mouth rinses on the surface hardness of dental resin nano-composite

    PubMed Central

    Khan, Aftab Ahmed; Siddiqui, Adel Zia; Mohsin, Syed Fareed; Al-Kheraif, Abdulaziz A.

    2015-01-01

    Objective: The aim of this research was to assess the effect of mouth rinses with and without alcohol on the hardness of dental nano-filled composite. Methods: The micro-hardness of fifty circular disk shaped specimens of 7 mm x 2 mm were measured after 14 days. Specimens were immersed into alcohol containing (Listerine and Colgate Perioguard) and alcohol-free (Prodent and Sensodyne Oral antiseptic) mouth rinse solutions. Artificial saliva served as the control. Vickers Micro-hardness was measured with a 30gram load for 30 seconds dwell time by using a diamond indenter. Significant differences were represented by p<0.05, whereas highly significant difference represented by p<0.01. The level of significance (p) was calculated with the help of repeated measure ANOVA. For multiple comparisons, Tukey’s multiple comparison test was used. Results: Statistical analysis revealed highly significant difference between specimens immersed in artificial saliva (control) and Listerine (p<0.01). Whereas significant difference were observed between control and Colgate Periogard (p<0.05). However, no significant difference was observed on comparing Prodent and Sensodyne Oral antiseptic mouth rinses with control group(p>0.05). Control specimens depicted highest value of micro-hardness(60.5746 ± 3.2703) compared to the lowest value seen in specimens immersed in Listerine solvent(54.4687 ± 1.0937). Conclusion: Alcohol containing mouth rinsing solutions have more deleterious effect on hardness of nano composites as compared to alcohol-free mouth rinses. PMID:26870121

  13. 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.

  14. 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. PMID:272719

  15. Retinal Sensitivity over Hard Exudates in Diabetic Retinopathy

    PubMed Central

    Raman, Rajiv; Nittala, Muneeswar Gupta; Gella, Laxmi; Pal, Swakshyar Saumya; Sharma, Tarun

    2015-01-01

    Purpose: To evaluate retinal sensitivity over hard exudates in correlation with the spectral domain optical coherence tomography (SD-OCT) findings in eyes with diabetic retinopathy. Methods: Twelve eyes of 10 patients with hard exudates associated with diabetic retinopathy were enrolled in this study. All subjects underwent a complete ophthalmic examination including SD-OCT (Copernicus, Zawiercie, Poland) and microperimetry (MP1; Nidek Technologies, Padova, Italy). Retinal sensitivity was measured, over the areas with hard exudates and compared to corresponding locations devoid of hard exudates, using a semi-automatic program. The size of the hard exudate plaque was measured using the measurement software in the microperimeter. Retinal thickness in the area of the hard exudates and foveal thickness were measured using SD-OCT. Results: Mean retinal sensitivity over hard exudates was 4.97 ± 4.17 dB which was significantly (P = 0.0001) reduced as compared to locations devoid of hard exudates. No significant correlation (r=-0.23, P = 0.45) was found between the size of the hard exudates and retinal sensitivity. A significant negative correlation was found between retinal sensitivity and retinal thickness at the area of the hard exudates (r=-0.65, P = 0.05), and between retinal sensitivity and foveal thickness (r=-0.91, P = 0.001). Conclusion: In eyes with diabetic retinopathy, retinal sensitivity was reduced due to the presence of hard exudates in the outer retinal layers and retinal thickening but this was not correlated with the size of the hard exudates. PMID:26425319

  16. Protecting Optical Replication Molds (Masters) With Hard Carbon

    NASA Astrophysics Data System (ADS)

    McCandless, James A.

    1988-07-01

    Delicate diamond turned Aluminum optics (DTO's) were made much more durable by Hard Carbon Coating (HCC). Submasters, steel masters and glass master surfaces were also made more rugged by the application of Hard Carbon. Multiple replicas were successfully made from these Hard Carbon coated masters and submasters. The merging of these three technologies (DTO's, HCC, and replicated optics) could produce lower cost precision aspheric mirrors and lenses.

  17. 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.

  18. Effect of Annealing Temperature on Hardness and Wear Resistance of Electroless Ni-B-Mo Coatings

    NASA Astrophysics Data System (ADS)

    Serin, Ihsan Gökhan; Göksenli, Ali

    2015-06-01

    Formation of nickel-boron-molybdenum (Ni-B-Mo) coating on steel by electroless plating and evaluation of their morphology, hardness and tribological properties post heat treatment at different temperatures for 1 h is investigated. The 25 μm thick coating is uniform and adhesion between the substrate and coating is good. Ni-B-Mo coating was amorphous-like structure in their as-plated condition and by 400°C heat-treated coating, nickel fully crystallized and nickel borides and molybdenum carbide were formed. All coatings exhibited higher hardness than the substrate steel. Hardness values of all coatings up to 400°C did not change distinctively but decreased partly beyond 400°C. Friction coefficient reached lowest value post heat treatment at 300°C but later increased with increasing tempering temperature. Wear resistance was lowest in as-plated coating; however it reached the highest value at 300°C. Worn surface of the coatings showed the abrasive wear as the dominant wear mechanism. An additional adhesive wear mechanism was detected in coating tempered at 550°C. Moreover, our results confirmed that the molybdenum addition improved the thermal stability of the resulting coating. Therefore, Ni-B-Mo coating has potential for application in precision mould, optical parts mould or bipolar plates, where thermal stability is essential.

  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. Exploring Existence Value

    NASA Astrophysics Data System (ADS)

    Madariaga, Bruce; McConnell, Kenneth E.

    1987-05-01

    The notion that individuals value the preservation of water resources independent of their own use of these resources is discussed. Issues in defining this value, termed "existence value," are explored. Economic models are employed to assess the role of existence value in benefit-cost analysis. The motives underlying existence value are shown to matter to contingent valuation measurement of existence benefits. A stylized contingent valuation experiment is used to study nonusers' attitudes regarding projects to improve water quality in the Chesapeake Bay. Survey results indicate that altruism is one of the motives underlying existence value and that goods other than environmental and natural resources may provide existence benefits.

  1. Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness

    PubMed Central

    Soylu, Elif Hilal; İde, Semra; Kılıç, Selim; Sipahi, Cumhur; Pişkin, Bulent; Gökçe, Hasan Suat

    2013-01-01

    PURPOSE The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). CONCLUSION After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments. PMID:24353888

  2. Orientational ordering and phase behaviour of binary mixtures of hard spheres and hard spherocylinders.

    PubMed

    Wu, Liang; Malijevský, Alexandr; Jackson, George; Müller, Erich A; Avendaño, Carlos

    2015-07-28

    We study the structure and fluid-phase behaviour of binary mixtures of hard spheres (HSs) and hard spherocylinders (HSCs) in isotropic and nematic states using the NPnAT ensemble Monte Carlo (MC) approach in which the normal component of the pressure tensor is fixed in a system confined between two hard walls. The method allows one to estimate the location of the isotropic-nematic phase transition and to observe the asymmetry in the composition between the coexisting phases, with the expected enhancement of the HSC concentration in the nematic phase. This is in stark contrast with the previously reported MC simulations where a conventional isotropic NPT ensemble was used. We further compare the simulation results with the theoretical predictions of two analytic theories that extend the original Parsons-Lee theory using the one-fluid and the many-fluid approximations [Malijevský et al., J. Chem. Phys. 129, 144504 (2008)]. In the one-fluid version of the theory, the properties of the mixture are related to an effective one-component HS system, while in the many-fluid theory, the components of the mixtures are represented as separate effective HS particles. The comparison reveals that both the one- and the many-fluid approaches provide a reasonably accurate quantitative description of the mixture including the predictions of the isotropic-nematic phase boundary and degree of orientational order of the HSC-HS mixture. PMID:26233163

  3. The Surface Free Energy of Hard Chain Fluids against a Hard Planar Wall

    NASA Astrophysics Data System (ADS)

    van Swol, Frank

    2000-03-01

    We present the first data for the interfacial properties of the simplest possible polymer fluid substrate interface, namely that of a hard chain fluid against a planar hard wall. We use molecular dynamics to calculate the surface free energy and the adsorption isotherms for hard chains of 2, 8, 20, 100, 400 and 1000 beads. We find that chain fluids differ markedly from the simple spheres in that both the adsorption and the surface free energy change sign and display an extremum as a function of density. The surface free energy exhibits a ‘Boyle density’ where at a nonzero density the surface free energy is equal to that of an ideal gas. The combined data can be fitted to a simple surface equation of state that expresses the free energy as a function of chain length and density. The results that we present here are the first of its kind for polymer fluids should proof particularly useful in further developing approximate density functional and integral equation approaches to polymer interfaces. We observe over most of the pressure range is linear with pressure.

  4. The influence of wheel/rail contact conditions on the microstructure and hardness of railway wheels.

    PubMed

    Molyneux-Berry, Paul; Davis, Claire; Bevan, Adam

    2014-01-01

    The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an "in-service" wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets. PMID:24526883

  5. Growth and mechanical and tribological characterization of multi-layer hard carbon films

    SciTech Connect

    Ager, J.; Brown, I.; Monteiro, O.; Knapp, J.A.; Follstaedt, D.M.; Nastasi, M.; Walter, K.C.; Maggiore, C.J.

    1996-12-31

    Vacuum-arc deposition is used to deposit multilayer C films by modulating the sample bias during deposition. Effect of varying the sublayer thickness in multilayer films consisting of alternating layers of ``hard`` (68.4 GPa, -100 V bias) and ``soft`` (27.5 GPa, - 200 V bias) was investigated. Films consisting of equal thickness layers of hard and soft material and an individual layer thickness varying from 10 to 35 nm were deposited. Mechanical property measurements were obtained by finite element modeling of nanoindentation load-displacement curves. The film hardness values were about 20% below the average of the component layers and relatively independent of the layer thickness. TEM revealed deterioration of the multilayer structure when the sublayer thickness was below 15 nm due to implantation damage of the hard layers caused by the energetic C{sup +} ions of the soft layers (-2000 V bias) deposited over them. Pin-on-disk wear tests show that the wear rate drops when sublayer thickness is decreased below 20 nm and remains constant with further decreases in the layer thickness.

  6. Numerical investigation of airflow inside a 1-in hard disk drive

    NASA Astrophysics Data System (ADS)

    Suriadi, M. A.; Tan, C. S.; Zhang, Q. D.; Yip, T. H.; Sundaravadivelu, K.

    2006-08-01

    The increasing application of the hard disk drive in consumer electronic devices has pushed the usage of the small form factor hard drives. At the same time, the data storage industry continues to enhance the capacity and performance of computer hard disk drive. The concerns of track mis-registration caused by various runout still remain with the form factor change. The objective of the current study is to numerically investigate the airflow characteristic inside a 1 in hard disk drive. The simulation model is constructed based on the currently available 1-in micro-drive in the market, with 3600 rpm disk rotation speed, thus the flow Reynolds number based on the disk tip radius is around 4.8×10 3. Two models with different actuator arm positions (outside and middle-disk) were studied. The simulation results show that the standard k-epsilon model used allows us to extract similar information and understanding as that from more developed numerical model. Good agreement in normalized velocity magnitude and flow pattern is observed between the numerical and experimental results. At different actuator arm positions, streamlines and velocity vectors plots show the effect of the actuator arm position to the flow pattern, especially around the arm. This arm position also affects the radial and tangential shear stress values over the disk, which may help to estimate the wind loss and power consumption.

  7. Hard X-ray spectra of cosmic gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Kane, S. R.; Share, G. H.

    1977-01-01

    Hard X-ray measurements of six gamma-ray bursts observed during the period from October 1969 to April 1971 are presented. The measurements were made with detectors on the OGO-5 and OSO-6 satellites. Spectra for five of the six bursts have been determined using measurements from both satellites in order to reduce ambiguities due to uncertain source locations. A significant fraction, about 20-60%, of the energy of the bursts falls in the hard X-ray range (20-130 keV). The time-integrated spectra have been fitted by power-law, exponential, and thermal-bremsstrahlung functions. They are consistent with power laws which steepen at energies of at least 150 keV, as reported earlier for two other bursts. Evidence for spectral variability from event to event in the hard X-ray region is presented. For a power-law representation, the power-law index has values ranging from approximately unity to 2.5. The hard X-ray spectra of the gamma-ray bursts differ significantly from those of the recently discovered 1-15-keV X-ray bursts.

  8. Manufacture, microstructure and mechanical properties of Mo-W-N nanostructured hard films

    SciTech Connect

    Yang, J.F.; Yuan, Z.G.; Zhang, G.G.; Wang, X.P.; Fang, Q.F.

    2009-10-15

    Mo{sub 1-x}W{sub x}N{sub y} (x = 0-0.67) hard films were fabricated on wafers of silicon and high speed steel by dc magnetron sputtering technique. The effect of tungsten concentration on the phase composition, microstructure, surface morphology, hardness, adhesion, and corrosion resistance of the films was studied by X-ray diffraction, scanning electron microscopy, nano-indentation, and scratch test. It was found that if the W concentration (x) in the film is in the range of 0-0.52, the films exhibit fcc (Mo,W)N{sub y} single phase where larger W atoms substituted Mo atoms in fcc MoN{sub y}. At higher x values (x > 0.52) the films exhibit a two-phase structure consisting of fcc (Mo,W)N{sub y} and pure bcc tungsten phase. The hardness of the Mo{sub 1-x}W{sub x}N{sub y} films increases at first with increasing x, and then decreases after passing a maximum. The maximum hardness of 47 GPa is obtained at x = 0.37 corresponding to an adhesion strength of 60 N. The Mo-W-N coated high speed steel has a lower corrosion current density and higher corrosion potential than the bare high speed steel substrates.

  9. The Influence of Wheel/Rail Contact Conditions on the Microstructure and Hardness of Railway Wheels

    PubMed Central

    Davis, Claire

    2014-01-01

    The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an “in-service” wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets. PMID:24526883

  10. Hard X-ray Flux from Low-Mass Stars in the Cygnus OB2 Association

    NASA Astrophysics Data System (ADS)

    Caramazza, M.; Drake, J. J.; Micela, G.; Flaccomio, E.

    2009-05-01

    We investigate the X-ray emission in the 20-40 keV band expected from the flaring low-mass stellar population in Cygnus OB2 assuming that the observed soft X-ray emission is due to a superposition of flares and that the ratio of hard X-ray to soft X-ray emission is described by a scaling found for solar flares by Isola and co-workers. We estimate a low-mass stellar hard X-ray flux in the 20-40 keV band in the range ~71031-71033 erg/s and speculate the limit of this values. Hard X-ray emission could lie at a level not much below the current observed flux upper limits for Cygnus OB2. Simbol-X, with its broad energy band (10-100 keV) and its sensitivity should be able to detect this emission and would provide insights into the hard X-ray production of flares on pre-main sequence stars.

  11. Values Education without Indoctrination.

    ERIC Educational Resources Information Center

    Weinstein, Joshua; Schwartz, Marilyn Schlachter

    1979-01-01

    Provides a theoretical and philosophical model for values education based on the work of Martin Buber. Reviews six steps that intercede between the initial meeting of teacher and student and the latter's formation of his/her values construction. (LRA)

  12. Effects of fast halogen and plasma arc curing lights on the surface hardness of orthodontic adhesives for lingual retainers.

    PubMed

    U?mez, Serdar; Bykyilmaz, Tamer; Karaman, Ali Ihya

    2003-06-01

    The aims of this study were to (1) identify the optimum cure times of 2 different lingual retainer adhesives with a conventional halogen, a fast halogen, and a plasma arc light by measuring Vickers surface hardness, and (2) determine whether different lights produce similar surface hardness values for the same adhesive resin material. The investigated plasma arc curing unit was the PowerPac (American Dental Technologies, Corpus Christi, Tex), and the fast halogen unit was the Optilux 501 (Kerr, Orange, Calif). A conventional curing unit, the Ortholux XT (3M Dental Products, St. Paul, Minn) was used as the control. Two orthodontic lingual retainer adhesives were used: Transbond Lingual Retainer (3M Unitek, Monrovia, Calif) and Light Cure Retainer (Reliance Orthodontic Products, Itasca, Ill). Concise (3M Dental Products) and diluted Concise were used as controls. Transbond Lingual Retainer was polymerized by the PowerPac light in 6 seconds, by the Optilux in 10 seconds, and by the conventional halogen light in 20 seconds. The minimum curing times for Light Cure Retainer adhesive were 15 seconds for PowerPac, 10 seconds for Optilux, and 40 seconds for conventional halogen. Surface hardness values for each resin did not differ significantly with different curing units. However, different adhesives demonstrated significantly different surface hardness values. Final Vickers surface hardness values (averaged across curing units) of Transbond Lingual Retainer, Concise, diluted Concise, and Light Cure Retainer were 62.8, 52.4, 46.0, and 40.4, respectively. Plasma arc or fast halogen units polymerize resin composite adhesive in much shorter times than do conventional curing units, without a significant loss in surface hardness. Therefore, these units are suggested for clinical use to save chairside time. PMID:12806343

  13. Modeling of the effect of freezer conditions on the hardness of ice cream using response surface methodology.

    PubMed

    Inoue, K; Ochi, H; Habara, K; Taketsuka, M; Saito, H; Ichihashi, N; Iwatsuki, K

    2009-12-01

    The effect of conventional continuous freezer parameters [mix flow (L/h), overrun (%), drawing temperature ( degrees C), cylinder pressure (kPa), and dasher speed (rpm)] on the hardness of ice cream under varying measured temperatures (-5, -10, and -15 degrees C) was investigated systematically using response surface methodology (central composite face-centered design), and the relationships were expressed as statistical models. The range (maximum and minimum values) of each freezer parameter was set according to the actual capability of the conventional freezer and applicability to the manufacturing process. Hardness was measured using a penetrometer. These models showed that overrun and drawing temperature had significant effects on hardness. The models can be used to optimize freezer conditions to make ice cream of the least possible hardness under the highest overrun (120%) and a drawing temperature of approximately -5.5 degrees C (slightly warmer than the lowest drawing temperature of -6.5 degrees C) within the range of this study. With reference to the structural elements of the ice cream, we suggest that the volume of overrun and ice crystal content, ice crystal size, and fat globule destabilization affect the hardness of ice cream. In addition, the combination of a simple instrumental parameter and response surface methodology allows us to show the relation between freezer conditions and one of the most important properties-hardness-visually and quantitatively on the practical level. PMID:19923588

  14. Values Drive the Plan

    ERIC Educational Resources Information Center

    Cook, Les P.

    2010-01-01

    Values-integrated strategic planning provides the opportunity to clarify professional values as one envisions a future that is exciting and perhaps a bit provocative. This chapter explores the role and importance of student affairs and institutional values in strategic planning. It also looks at the historical roots of the profession and methods

  15. Hierarchical Classification of Values

    ERIC Educational Resources Information Center

    Ergen, Gürkan

    2015-01-01

    Values are of utmost importance for the creation, development and sustainability of a life worthy of human dignity. However, because even superficial views of values are regarded as values themselves, they have become relative and become degenerated; therefore, they have lost the properties--potentials and powers--essential to human dignity. This…

  16. Hierarchical Classification of Values

    ERIC Educational Resources Information Center

    Ergen, Grkan

    2015-01-01

    Values are of utmost importance for the creation, development and sustainability of a life worthy of human dignity. However, because even superficial views of values are regarded as values themselves, they have become relative and become degenerated; therefore, they have lost the properties--potentials and powers--essential to human dignity. This

  17. Emergy and Nonmarket Value

    EPA Science Inventory

    The purpose of this study is to better understand the differences and similarities between emergy and nonmarket economic valuation, when both are applied to value the same policies or development alternatives. The emdollar value of a good or service often exceeds the market value...

  18. Hospital perceived value.

    PubMed

    Moliner, Miguel A

    2006-01-01

    The creation, distribution and communication of value have been considered to be the key element of marketing (American Marketing Association, 2004, www.marketingpower.com). The aim of this article is to identify the indicators of perceived value in a hospital context. The results show that perceived quality and emotions are key dimensions of perceived value. PMID:17077707

  19. Values in Further Education.

    ERIC Educational Resources Information Center

    Halliday, John, Ed.

    This book explores educational values in the British further education system. Following an introductory discussion of educational values by the editor, John Halliday, the book contains 21 short essays organized in the areas of cultural values, curriculum, and management and staff development. The following are included: "Democratic…

  20. Values Drive the Plan

    ERIC Educational Resources Information Center

    Cook, Les P.

    2010-01-01

    Values-integrated strategic planning provides the opportunity to clarify professional values as one envisions a future that is exciting and perhaps a bit provocative. This chapter explores the role and importance of student affairs and institutional values in strategic planning. It also looks at the historical roots of the profession and methods…

  1. Gibbs measures for fertile hard-core models on the Cayley tree

    NASA Astrophysics Data System (ADS)

    Khakimov, R. M.

    2016-02-01

    We study fertile hard-core models with the activity parameter λ > 0 and four states on the Cayley tree. It is known that there are three types of such models. For each of these models, we prove the uniqueness of the translation-invariant Gibbs measure for any value of the parameter λ on the Cayley tree of order three. Moreover, for one of the models, we obtain critical values of λ at which the translation-invariant Gibbs measure is nonunique on the Cayley tree of order five. In this case, we verify a sufficient condition (the Kesten-Stigum condition) for a measure not to be extreme.

  2. Surface Effects on Young's Modulud and Hardness of Fused Silica by Nanoindentation Study

    SciTech Connect

    Zheng, L.; Schmid, A.W.; Lambropoulos, J.C.

    2007-01-24

    The surface Young's modulus (E) and hardness (H) of fused silica samples have been studied by nanoindentation. Two factors strongly affect the results of E and H. One factor is the polishing quality of the fused silica surface. Poor polishing quality produces much smaller E and H than the literature values for bulk fused silica. The second factor is surface flatness. Even for a well-polished silica surface, an "arch bridge effect" may hinder the measurements of the true values of E and H. A correction procedure is proposed to eliminate this effect, and the corrected results show substantial improvements.

  3. The Hard X ray Telescope Mission

    NASA Technical Reports Server (NTRS)

    Gorenstein, Paul

    1997-01-01

    The Hard X Ray Telescope (HXT) was selected for study as a possible new intermediate size mission for the early 21st century. Its principal attributes are: (1) multiwavelength observing with a system of focussing telescopes that collectively observe from the UV to over 1 MeV, (2) much higher sensitivity and much better angular resolution in the 10100 keV band, and (3) higher sensitivity for detecting gamma ray lines of known energy in the 100 keV to 1 MeV band. The institutions collaborating in the study are: Smithsonian Astrophysical Observatory, Marshall Space Flight Center, Naval Research Laboratory, Goddard Space Flight Center, Argonne National Laboratory, Danish Space Research Institute, Osservatorio Astronomica di Brera (Merate), and Centre d'Etudes Spatiale des Rayonnements (Toulouse). The instrumentation includes several grazing incidence double conical telescopes with multilayer coatings that focus up to 100 keV and a single Laue crystal telescope that functions to 1 MeV. The detectors are CCDs, and germanium, and/or CdZnTe position sensitive arrays.

  4. The smallest hard X-ray flare?

    NASA Astrophysics Data System (ADS)

    Glesener, Lindsay; Krucker, Sam; Hannah, Iain; Smith, David M.; Grefenstette, Brian; Marsh, Andrew; Hudson, Hugh S.; White, Stephen M.; Chen, Bin

    2016-05-01

    We report a NuSTAR observation of a small solar flare on 2015 September 1, estimated to be on the order of a GOES class A.05 flare in brightness. This flare is fainter than any hard X-ray (HXR) flares in the existing literature, and with a peak rate of only ∼5 counts s‑1 detector‑1 observed by RHESSI, is effectively the smallest that can just barely be detected by the current standard (indirectly imaging) solar HXR instrumentation, though we expect that smaller flares will continue to be discovered as instrumental and observational techniques progress. The flare occurred during a solar observation by the highly sensitive NuSTAR astrophysical HXR spacecraft, which used its direct focusing optics to produce detailed flare spectra and images. The flare exhibits properties commonly observed in larger flares, including a fast rise and more gradual decay, and similar spatial dimensions to the RHESSI microflares. We will discuss the presence of non-thermal (flare-accelerated) electrons during the impulsive phase. The flare is small in emission measure, temperature, and energy, though not in physical dimensions. Its presence is an indication that flares do indeed scale down to smaller energies and retain what we customarily think of as “flarelike” properties.

  5. 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

  6. 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.

  7. 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.

  8. Revisiting the phase diagram of hard ellipsoids.

    PubMed

    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)] 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. PMID:22482570

  9. 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.

  10. 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.

  11. Hazards of the 'hard cash': hypersensitivity pneumonitis.

    PubMed

    Kupeli, Elif; Karnak, Demet; Sak, Serpil Dizbay; Kayacan, Oya

    2010-01-01

    Hypersensitivity pneumonitis (HP) is a nonimmunoglobulin E-related immune-mediated parenchymal lung disease. A 45-year-old woman who was a lifelong nonsmoker with a six-month history of frequent episodes of cough and dyspnea was admitted to hospital. She had been working as a money counter for 20 years at a central bank. Bibasilar crackles on lung auscultation, ground-glass opacities and a mosaic pattern on high-resolution computed tomography, restrictive abnormality on pulmonary function tests and mild hypoxemia were the prominent findings. Bronchoalveolar lavage fluid analysis revealed a predominance of CD4-positive T cells, and she tested positive on her natural challenge test. She was diagnosed with subacute HP based on established criteria. She was advised to discontinue counting fresh banknotes. Prednisolone was commenced, then tapered to discontinue in the ensuing six months. Clinical and radiological improvement was achieved within two months. To the authors' knowledge, the present report is the first to describe 'hard cash HP', possibly caused by chipping dust or printing dye. PMID:21038004

  12. Unraveling Quantum Annealers using Classical Hardness.

    PubMed

    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

  13. 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.

  14. 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.

  15. Hard Transparent Arrays for Polymer Pen Lithography.

    PubMed

    Hedrick, James L; Brown, Keith A; Kluender, Edward J; Cabezas, Maria D; Chen, Peng-Cheng; Mirkin, Chad A

    2016-03-22

    Patterning nanoscale features across macroscopic areas is challenging due to the vast range of length scales that must be addressed. With polymer pen lithography, arrays of thousands of elastomeric pyramidal pens can be used to write features across centimeter-scales, but deformation of the soft pens limits resolution and minimum feature pitch, especially with polymeric inks. Here, we show that by coating polymer pen arrays with a ∼175 nm silica layer, the resulting hard transparent arrays exhibit a force-independent contact area that improves their patterning capability by reducing the minimum feature size (∼40 nm), minimum feature pitch (<200 nm for polymers), and pen to pen variation. With these new arrays, patterns with as many as 5.9 billion features in a 14.5 cm(2) area were written using a four hundred thousand pyramid pen array. Furthermore, a new method is demonstrated for patterning macroscopic feature size gradients that vary in feature diameter by a factor of 4. Ultimately, this form of polymer pen lithography allows for patterning with the resolution of dip-pen nanolithography across centimeter scales using simple and inexpensive pen arrays. The high resolution and density afforded by this technique position it as a broad-based discovery tool for the field of nanocombinatorics. PMID:26928012

  16. Monodisperse hard rods in external potentials

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    We consider linear arrays of cells of volume Vc populated by monodisperse rods of size σ Vc,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 Vc→0 ,σ →∞ at nonzero and finite σ Vc , 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.

  17. 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. PMID:26565173

  18. Handling Missing Attribute Values

    NASA Astrophysics Data System (ADS)

    Grzymala-Busse, Jerzy W.; Grzymala-Busse, Witold J.

    In this chapter methods of handling missing attribute values in Data Mining are described. These methods are categorized into sequential and parallel. In sequential methods, missing attribute values are replaced by known values first, as a preprocessing, then the knowledge is acquired for a data set with all known attribute values. In parallel methods, there is no preprocessing, i.e., knowledge is acquired directly from the original data sets. In this chapter the main emphasis is put on rule induction. Methods of handling attribute values for decision tree generation are only briefly summarized.

  19. A Group Orientation Approach for Facilitating the Work of Adjustment of the Hard-Core Unemployed. Final Report.

    ERIC Educational Resources Information Center

    Rosen, Hjalmar; Teahan, John E.

    The major objective of this project was to achieve a lasting integration of Negro hard-core unemployed men in an ongoing corporate work force. It was intended to develop values necessary for successful employment, particularly with regard to regularity of attendance, punctuality, conformity to work rules and regulations, and motivation to accept…

  20. WHEAT QUALITY COUNCIL HARD SPRING WHEAT 2001 CROP REPORT.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Hard Spring Wheat Technical Committee provides quality data relating the milling and baking properties of experimental lines of wheat that were grown and tested in the 2001 crop. The data in this report were developed under code and provided to the Wheat Quality Council (WQC) by the USDA Hard R...

  1. 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…

  2. AMORPHOUS ALLOY SURFACE COATINGS FOR HARD CHROMIUM REPLACEMENT - PHASE I

    EPA Science Inventory

    Hard chromium coatings (0.25 to10 mil thick) are used extensively for imparting wear and erosion resistance to components in both industrial and military applications. The most common means of depositing hard chromium has been through the use of chromic acid baths containing ...

  3. KEY COMPARISON: Final report on CCM Vickers hardness key comparison

    NASA Astrophysics Data System (ADS)

    Herrmann, Konrad

    2006-01-01

    In the framework of the Working Group on Hardness (WGH) of the Consultative Committee for Mass and Related Quantities (CCM) in the year 2003 the key comparison Vickers hardness was finished. In the comparison the hardness laboratories of the following national metrology institutes participated: IMGC (Italy), NIST (USA), INMETRO (Brazil), NIM (PR China), KRISS (Republic of Korea), NMIJ (Japan), CMI (Czech Republic), GUM (Poland) and NPL (UK), and PTB (Germany) served as the pilot laboratory. The comparison of the Vickers primary hardness standard machines was carried out with three sets of hardness reference blocks of the Vickers scales HV0,2, HV1 and HV30, each with the hardness levels 240 HV, 540 HV and 840 HV. The Vickers key comparison for all test force ranges used (Vickers microhardness, low-force Vickers hardness, Vickers hardness) delivered the following results. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  4. Critical Configurations of Hard Disks on the Torus

    Energy Science and Technology Software Center (ESTSC)

    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.

  5. 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...

  6. 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...

  7. Quantitative Trait Loci Mapping of Seed Hardness in Soybean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean seeds with undesirable texture cause processing complications in soyfood production. Seed hardness is an important quality attribute for food-grade soybeans. The objective of this study was to identify QTL associated with seed hardness in soybean. Three generations of F2-derived lines (159 F...

  8. 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…

  9. HARD RED SPRING WHEAT QUALITY REPORT: 2000/2001 CROP.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Commercially grown cultivars and experimental lines of hard red spring wheat were grown by breeders at cooperative experiment stations throughout the major spring wheat growing regions of the United States. Hard spring wheat was tested for kernel, milling, flour, dough, and baking quality. In 2000...

  10. 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.…

  11. Hard proximity induced superconducting gap in semiconductor - superconductor epitaxial hybrids

    NASA Astrophysics Data System (ADS)

    Jespersen, Thomas; Krogstrup, Peter; Ziino, Nino; Albrecht, Sven; Chang, Willy; Madsen, Morten; Johnson, Erik; Kuemmeth, Ferdinand; Nygård, Jesper; Marcus, Charles

    2015-03-01

    We present molecular beam epitaxy grown InAs semiconductor nanowires capped with a shell of aluminum (superconductor). The hybrid wires are grown without breaking vacuum, resulting in an epitaxial interface between the two materials as demonstrated by detailed transmission electron microscopy and simulations. The domain matching at the interface is discussed. Incorporating the epitaxial nanowire hybrids in electrical devices we performed detailed tunneling spectroscopy of the proximity induced superconducting gap in the InAs core at 20 mK. We find the sub-gap conductance being at least a factor 200 smaller than the normal state value (gap hardness). This is a significant improvement compared to devices fabricated by conventional lithographic methods and metal evaporation showing no more than a factor of ~ 5 . The epitaxial hybrids seem to solve the soft gap problem associated with the use of nanowire hybrids for future applications in topological quantum information based on Majorana zero modes. Research supported by Microsoft Station Q, Danish National Research Foundation, Villum Foundation, Lundbeck Foundation, and the European Commission.

  12. Fuzzy and hard clustering analysis for thyroid disease.

    PubMed

    Azar, Ahmad Taher; El-Said, Shaimaa Ahmed; Hassanien, Aboul Ella

    2013-07-01

    Thyroid hormones produced by the thyroid gland help regulation of the body's metabolism. A variety of methods have been proposed in the literature for thyroid disease classification. As far as we know, clustering techniques have not been used in thyroid diseases data set so far. This paper proposes a comparison between hard and fuzzy clustering algorithms for thyroid diseases data set in order to find the optimal number of clusters. Different scalar validity measures are used in comparing the performances of the proposed clustering systems. To demonstrate the performance of each algorithm, the feature values that represent thyroid disease are used as input for the system. Several runs are carried out and recorded with a different number of clusters being specified for each run (between 2 and 11), so as to establish the optimum number of clusters. To find the optimal number of clusters, the so-called elbow criterion is applied. The experimental results revealed that for all algorithms, the elbow was located at c=3. The clustering results for all algorithms are then visualized by the Sammon mapping method to find a low-dimensional (normally 2D or 3D) representation of a set of points distributed in a high dimensional pattern space. At the end of this study, some recommendations are formulated to improve determining the actual number of clusters present in the data set. PMID:23357404

  13. Hard X-ray polarimetry with Astrosat-CZTI

    NASA Astrophysics Data System (ADS)

    Vadawale, S. V.; Chattopadhyay, T.; Rao, A. R.; Bhattacharya, D.; Bhalerao, V. B.; Vagshette, N.; Pawar, P.; Sreekumar, S.

    2015-06-01

    X-ray polarimetry is largely an unexplored area of an otherwise mature field of X-ray astronomy. Except for a few early attempts during the 1970s, no dedicated X-ray polarimeter has been flown during the past four decades. On the other hand, the scientific value of X-ray polarization measurement has been well known for a long time, and there has been significant technical progress in developing sensitive X-ray polarimeters in recent years. But there are no approved dedicated X-ray polarimetric experiments to be flown in the near future, so it is important to explore the polarimetric capabilities of other existing or planned instruments and examine whether they can provide significant astrophysical polarization measurements. In this paper, we present experimental results to show that the CZTI instrument onboard the forthcoming Indian astronomy mission, Astrosat, will be able to provide sensitive measurements of X-ray polarization in the energy range of 100-300 keV. CZTI will be able to constrain any intrinsic polarization greater than ~40% for bright X-ray sources (>500 mCrab) within a short exposure of ~100 ks with a 3-sigma confidence level. We show that this seemingly "modest" sensitivity can play a very significant role in addressing long pending questions, such as the contribution of relativistic jets to hard X-rays in black hole binaries and X-ray emission mechanism and geometry in X-ray pulsars.

  14. Combining Hard and Soft Data in Drought Research

    NASA Astrophysics Data System (ADS)

    Van Loon, A.

    2014-12-01

    As natural scientists we are used to doing quantitative analysis on observations or simulations of hydrometeorological variables. In many fields of hydrology, however, other sources of information are available that can broaden our knowledge of a hydrological system or process. In this pop-up I will show how the combination of hard and soft data in drought research has improved our knowledge of drought in cold climates and the impacts of drought on agriculture. We used data from historical archives and modern drought impact databases and used this information side-by-side with hydrometeorological observations and outcomes of large-scale hydrological models. I will present the pros and cons of using different types of data. This presentation has two aims: i) it is an example to other fields of hydrology, in which other data sources and different type of analysis could have an added value as well, and, ii) it calls for a wider accessibility, collection and consolidation of soft data to serve its use in hydrology.

  15. Super radiation hard vacuum phototriodes for the CMS endcap ECAL

    NASA Astrophysics Data System (ADS)

    Gusev, Yu. I.; Kovalev, A. I.; Levchenko, L. A.; Lukianov, V. N.; Moroz, F. V.; Mamaeva, G. A.; Seliverstov, D. M.; Trautman, V. Yu.; Yakorev, D. O.

    2004-12-01

    The energy resolution ?/E of the electromagnetic calorimeter (ECAL) in the energy range of 50-500 GeV is defined mainly by two terms: stochastic ?/?E and constant C. The photoreadout of the CMS Endcap ECAL consists of vacuum phototriodes (VPT), which are broadening a signal from np photoelectrons characterized by the excess noise factor F=np(?/E)2. The technical specification of the CMS ECAL requires the value of F to be smaller than 4 in the CMS LHC environment during 10 years of detector operation. In this paper we present results of the VPT performance study in a magnetic field up to 4 T, in a gamma radiation field of 0-50 kGy and in a neutron fluence of 71015 n/cm2. The standard phototriodes FEU-188 with faceplates from UV glass used in CMS ECAL as well as VPTs with super radiation hard cerium-doped glasses were investigated at the 60Co gamma facility, a neutron generator and a nuclear reactor in the Petersburg Nuclear Physics Institute (PNPI). The dependence of the VPT gain and the excess noise factor in magnetic fields on the fine-mesh plane orientation has also been studied.

  16. The impulsive hard X-rays from solar flares

    NASA Technical Reports Server (NTRS)

    Leach, J.

    1984-01-01

    A technique for determining the physical arrangement of a solar flare during the impulsive phase was developed based upon a nonthermal model interpretation of the emitted hard X-rays. Accurate values are obtained for the flare parameters, including those which describe the magnetic field structure and the beaming of the energetic electrons, parameters which have hitherto been mostly inaccessible. The X-ray intensity height structure can be described readily with a single expression based upon a semi-empirical fit to the results from many models. Results show that the degree of linear polarization of the X-rays from a flaring loop does not exceed 25 percent and can easily and naturally be as low as the polarization expected from a thermal model. This is a highly significant result in that it supersedes those based upon less thorough calculations of the electron beam dynamics and requires that a reevaluation of hopes of using polarization measurements to discriminate between categories of flare models.

  17. Influence of plastic deformation upon the half-width of engineering metallic materials in hard state

    NASA Astrophysics Data System (ADS)

    Li, J. B.; Xu, H. B.; Chen, R.; Wang, Z. G.

    1996-11-01

    The half-width values of the X-ray diffraction profiles are frequently used to characterize the static strength of a strengthened surface, or the depth distribution of this mechanical parameter, in a strengthened surface layer, especially in a shot-peening affected layer. However, for the unpeened surface and the base material of the shot-peened specimen of an alloy steel treated in hard state, the experimental results shown in this article indicate that uniaxial tensile or compressive plastic deformation increases the yield strengths while it decreases the half-width values. The half-width values of the shot-peened surface and surface layer greatly decrease, whereas the yield strength of this surface remarkably increases. Accordingly, in the authors’ opinion, the half-width values could not correctly describe the static strengths of hard metallic materials, and, contrary to the viewpoint put forward by a lot of researchers, the shot-peened surfaces of such materials are work hardened instead of work softened. A model demonstrating that plastic deformation reduces the half-width values by decreasing the second kind internal stresses is developed.

  18. Synthesis, Structure, and Properties of Refractory Hard-Metal Borides

    NASA Astrophysics Data System (ADS)

    Lech, Andrew Thomas

    As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB2 and WB4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called "super-hard metals".

  19. Properties of vacuum arc deposited amorphous hard carbon films

    SciTech Connect

    Anders, S.; Anders, A.; Raoux, S.

    1995-04-01

    Amorphous hard carbon films formed by vacuum arc deposition are hydrogen-free, dense, and very hard. The properties of amorphous hard carbon films depend strongly on the energy of the incident ions. A technique which is called Plasma Immersion Ion Implantation can be applied to vacuum arc deposition of amorphous hard carbon films to influence the ion energy. The authors have studied the influence of the ion energy on the elastic modulus determined by an ultrasonic method, and have measured the optical gap for films with the highest sp{sup 3} content they have obtained so far with this deposition technique. The results show an elastic modulus close to that of diamond, and an optical gap of 2.1 eV which is much greater than for amorphous hard carbon films deposited by other techniques.

  20. Nanoindentation of soft films on hard substrates: Experiments and finite element simulations

    SciTech Connect

    Pharr, G.M.; Tsui, T.Y.; Bolshakov, A.; Hay, J.C.

    1997-12-31

    Experiments and finite element simulations have been performed to examine error measurement of hardness and elastic modulus caused by pile-up when soft films deposited on hard substrates are tested by nanoindentation methods. Pile-up is exacerbated in soft-film/hard-substrate systems by the constraint imposed on plastic deformation in the film by the relatively non-deformable substrate. To experimentally examine pile-up effects, soft aluminum films with thicknesses of 240, 650, and 1700 nm were deposited on hard soda-lime glass substrates and tested by nanoindentation techniques. This system is attractive because the elastic modulus of the film and the substrate are approximately the same, but the substrate is harder than the film by a factor of about ten. Consequently, substrate influences on the indentation load-displacement behavior are manifested primarily by differences in the plastic flow characteristics alone. The elastic modulus of the film/substrate system, as measured by nanoindentation techniques, exhibits an increase with indenter penetration depth which peaks at a value approximately 30% greater than the true film modulus at a penetration depth close to the film thickness. Finite element simulation shows that this unusual behavior is caused by substrate-induced enhancement of pile-up. Finite element simulation also shows that the amount of pile-up increases with increasing penetration depth, and that the pile-up geometry depends on the work-hardening characteristics of the film. Because of these effects, nanoindentation techniques overestimate the true film hardness and elastic modulus by as much as 68% and 35%, respectively, depending on the work-hardening behavior of the film and the indenter penetration depth. The largest errors occur in non-work-hardening materials at penetration depths close to the film thickness, for which substrate-induced enhancement of pile-up is greatest.

  1. Example of quality assurance and optimization system for super hard materials turning

    NASA Astrophysics Data System (ADS)

    Kowalczyk, R.; Zebala, W.

    2014-11-01

    This paper introduces an example of automated intelligent system for super hard materials turning process that works according to a designed algorithm. Main task of the proposed system is to supervise the super hard materials turning process (acronym: ISSSHMT - Intelligent Supervision System of Super Hard Materials Turning) with the maximal metal removal rate Qvmax, the amplitude of natural tool wear and the measurement of values that define the state of the turning process (e.g. magnitude of cutting force, surface quality, temperature in workspace). Based on the measured values it is possible to select the optimal machining parameters (vc, ap, f), for which desired surface quality and dimensional precision can be achieved for the maximal metal removal rate Qvmax. Presented system (ISSSHMT) can be used for any CNC machine - accommodation for workspace and construction of the machine. An example of NC-code program that allows using the data acquired from the ISSSHMT system by a CNC machine control unit is presented. Optimization of the process and cost cutting can be achieved with the usage of proper target functions, for products machined with required precision class.

  2. Hardness and microstructural variation of Al-Mg-Mn-Sc-Zr alloy.

    PubMed

    Ikeshita, Sumiha; Strodahs, Ansis; Saghi, Zineb; Yamada, Kazuhiro; Burdet, Pierre; Hata, Satoshi; Ikeda, Ken-Ichi; Midgley, Paul A; Kaneko, Kenji

    2016-03-01

    Variations of Vickers hardness were observed in Al-Mg-Mn alloy and Al-Mg-Mn-Sc-Zr alloy at different ageing times, ranging from a peak value of 81.2 HV at 54ks down to 67.4 HV at 360ks, below the initial hardness value, 71.8 HV at 0ks for the case of Al-Mg-Mn-Sc-Zr alloy. Microstructures of samples at each ageing stage were examined carefully by transmission electron microscopes (TEMs) both in two-dimensions and three-dimensions. The presence of different types, densities, and sizes of particles were observed dispersed spherical Al3Sc1-xZrx and also block-shaped Al3Sc precipitates growing along <100>Al with facets {100} and {110} of the precipitates. TEM analysis both in two-dimensions and three-dimensions, performed on various samples, confirmed the direct correlation between the hardness and the density of Al3Sc. PMID:26748212

  3. 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.

  4. 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 appropriate. In general, this Thesis evaluates diverse tooth surface modulations, for which several experimental methodologies had to be developed. These will be invaluable for the development of succeeding generations of surface modulating agents.

  5. High efficiency, radiation-hard solar cells

    SciTech Connect

    Ager III, J.W.; Walukiewicz, W.

    2004-10-22

    The direct gap of the In{sub 1-x}Ga{sub x}N alloy system extends continuously from InN (0.7 eV, in the near IR) to GaN (3.4 eV, in the mid-ultraviolet). This opens the intriguing possibility of using this single ternary alloy system in single or multi-junction (MJ) solar cells of the type used for space-based surveillance satellites. To evaluate the suitability of In{sub 1-x}Ga{sub x}N as a material for space applications, high quality thin films were grown with molecular beam epitaxy and extensive damage testing with electron, proton, and alpha particle radiation was performed. Using the room temperature photoluminescence intensity as a indirect measure of minority carrier lifetime, it is shown that In{sub 1-x}Ga{sub x}N retains its optoelectronic properties at radiation damage doses at least 2 orders of magnitude higher than the damage thresholds of the materials (GaAs and GaInP) currently used in high efficiency MJ cells. This indicates that the In{sub 1-x}Ga{sub x}N is well-suited for the future development of ultra radiation-hard optoelectronics. Critical issues affecting development of solar cells using this material system were addressed. The presence of an electron-rich surface layer in InN and In{sub 1-x}Ga{sub x}N (0 < x < 0.63) was investigated; it was shown that this is a less significant effect at large x. Evidence of p-type activity below the surface in Mg-doped InN was obtained; this is a significant step toward achieving photovoltaic action and, ultimately, a solar cell using this material.

  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. Radiation hardness of CMS pixel barrel modules

    NASA Astrophysics Data System (ADS)

    Rohe, T.; Bean, A.; Erdmann, W.; Kästli, H.-C.; Khalatyan, S.; Meier, B.; Radicci, V.; Sibille, J.

    2010-12-01

    Pixel detectors are used in the innermost part of the multi purpose experiments at the LHC and are therefore exposed to the highest fluences of ionising radiation, which in this part of the detectors consists mainly of charged pions. The radiation hardness of all detector components has been thoroughly tested up to the fluences expected at the LHC. In case of an LHC upgrade, the fluence will be much higher and it is not yet clear how long the present pixel modules will stay operative in such a harsh environment. The aim of this study was to establish such a limit as a benchmark for other possible detector concepts considered for the upgrade. As the sensors and the readout chip are the parts most sensitive to radiation damage, samples consisting of a small pixel sensor bump-bonded to a CMS-readout chip (PSI46V2.1) have been irradiated with positive 200 MeV pions at PSI up to 6×1014 neq/cm2 and with 21 GeV protons at CERN up to 5×1015 neq/cm2. After irradiation the response of the system to beta particles from a 90Sr source was measured to characterise the charge collection efficiency of the sensor. Radiation induced changes in the readout chip were also measured. The results show that the present pixel modules can be expected to be still operational after a fluence of 2.8×1015 neq/cm2. Samples irradiated up to 5×1015 neq/cm2 still see the beta particles. However, further tests are needed to confirm whether a stable operation with high particle detection efficiency is possible after such a high fluence.

  8. 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...

  9. From Hard to Reach to How to Reach: A Systematic Review of the Literature on Hard-to-Reach Families

    ERIC Educational Resources Information Center

    Boag-Munroe, Gill; Evangelou, Maria

    2012-01-01

    This paper presents a review of the literature relating to hard-to-reach families which has been published over the last 12 years in the UK, USA, Canada and Australia. The purpose of the review was twofold: to gain insights to understandings of the term "hard-to-reach" within these services--education, health and social--which might be aiming to

  10. The problem with value

    PubMed Central

    O’Doherty, John P.

    2015-01-01

    Neural correlates of value have been extensively reported in a diverse set of brain regions. However, in many cases it is difficult to determine whether a particular neural response pattern corresponds to a value-signal per se as opposed to an array of alternative non-value related processes, such as outcome-identity coding, informational coding, encoding of autonomic and skeletomotor consequences, alongside previously described “salience” or “attentional” effects. Here, I review a number of experimental manipulations that can be used to test for value, and I identify the challenges in ascertaining whether a particular neural response is or is not a value signal. Finally, I emphasize that some non-value related signals may be especially informative as a means of providing insight into the nature of the decision-making related computations that are being implemented in a particular brain region. PMID:24726573

  11. Ultrasonically bonded value assembly

    NASA Technical Reports Server (NTRS)

    Salvinski, R. J. (Inventor)

    1975-01-01

    A valve apparatus capable of maintaining a fluid-tight seal over a relatively long period of time by releasably bonding a valve member to its seat is described. The valve member is bonded or welded to the seat and then released by the application of the same energy to the bond joint. The valve member is held in place during the bonding by a clamping device. An appropriate force device can activate the opening and closing of the valve member. Various combinations of material for the valve member and valve seat can be utilized to provide an adequate sealing bond. Aluminum oxide, stainless steel, inconel, tungsten carbide as hard materials and copper, aluminum, titanium, silver, and gold as soft materials are suggested.

  12. Value contamination avoidance devices

    NASA Technical Reports Server (NTRS)

    Endicott, D. L.

    1975-01-01

    Mechanical redesign methods were used to minimize contamination damage of conventional fluid components and a contamination separator device was developed for long term reusable space vehicles. These were incorporated into an existing 50.8 mm poppet valve and tested for damage tolerance in a full size open loop flow system with gaseous and liquid nitrogen. Cyclic and steady flow conditions were tested with particles of 125 to 420 micrometers aluminum oxide dispersed in the test fluids. Nonflow life tests (100,000 cycles) were made with two valve configurations in gaseous hydrogen. The redesigned valve had an acceptable cycle life and improved tolerance to contamination damage when the primary sealing surfaces were coated with thin coatings of hard plastic (Teflon S and Kynar). Analytical studies and flow testing were completed of four different versions of the separator. overall separation efficiencies in the 55-90% range were measured with these non-optimum configurations.

  13. INFLUENCE OF POST-CURE TREATMENTS ON HARDNESS AND MARGINAL ADAPTATION OF COMPOSITE RESIN INLAY RESTORATIONS: AN IN VITRO STUDY

    PubMed Central

    Poskus, Laiza Tatiana; Latempa, Antonio Marcelo Accetta; Chagas, Maurcio Alves; da Silva, Eduardo Moreira; Leal, Mariana Pareira da Silva; Guimares, Jos Guilherme Antunes

    2009-01-01

    Objectives: The purpose of this study was to evaluate the Vickers hardness number (VHN) and the in vitro marginal adaptation of inlay restorations of three hybrid composite resins (Filtek Z250, Opallis and Esthet-X) subjected to two post-cure treatments. Material and Methods: For the microhardness test, three different groups were prepared in accordance with the post-cure treatments: control group (only light cure for 40 s), autoclave group (light cure for 40 s + autoclave for 15 min at 130C); and microwave group (light cure for 40 s + microwave for 3 min at 450 W). To assess the marginal adaptation, the composite resin was inserted incrementally into a mesial-occlusal-distal cavity brass mold and each increment light-cured for 40 s. A previous reading in micrometers was taken at the cervical wall, using a stereomicroscope magnifying glass equipped with a digital video camera and image-analysis software. Subsequently, the specimens were subjected to the post-cure treatments (autoclave and microwave) and a reading was taken again at the cervical wall. Data were compared using ANOVA for the hardness test, split-plot ANOVA for the adaptation assessment and Tukey's test for multiple comparisons. A significance level of 5% was adopted for all analyses. Results: The post-cure treatments increased the hardness of conventional composites (p<0.001) and the gap values of inlay restorations (p<0.01). Filtek Z250 showed higher hardness (p<0.001) and lower gap values than Opallis and Esthet-X (p<0.05). Gap values did not exceed 90 ?m for any of the experimental conditions. Conclusion: The post-cure treatments increased the VHN and the gap values on the cervical floor of composite resin inlays. Moreover, Filtek Z250 showed the best results, with higher hardness and lower gap values. PMID:20027437

  14. Demands, values, and burnout

    PubMed Central

    Leiter, Michael P.; Frank, Erica; Matheson, Timothy J.

    2009-01-01

    OBJECTIVE T o explore the interaction between workload and values congruence (personal values with health care system values) in the context of burnout and physician engagement and to explore the relative importance of these factors by sex, given the distinct work patterns of male and female physicians. DESIGN National mailed survey. SETTING Canada. PARTICIPANTS A random sample of 8100 Canadian physicians (response rate 40%, N = 3213); 2536 responses (from physicians working more than 35 hours per week) were analyzed. MAIN OUTCOME MEASURES Levels of burnout, values congruence, and workload, by sex, measured by the Maslach Burnout Inventory—General Scale and the Areas of Worklife Scale. RESULTS Results showed a moderate level of burnout among Canadian physicians, with relatively positive scores on exhaustion, average scores on cynicism, and mildly negative scores on professional efficacy. A series of multiple regression analyses confirmed parallel main effect contributions from manageable workload and values congruence. Both workload and values congruence predicted exhaustion and cynicism for men and women (P = .001). Only values congruence provided a significant prediction of professional efficacy for both men and women (P = .001) These predictors interacted for women on all 3 aspects of burnout (exhaustion, cynicism, and diminished efficacy). Howevever, overall levels of the burnout indicators departed only modestly from normative levels. CONCLUSION W orkload and values congruence make distinct contributions to physician burnout. Work overload contributes to predicting exhaustion and cynicism; professional values crises contribute to predicting exhaustion, cynicism, and low professional efficacy. The interaction of values and workload for women in particular has implications for the distinct work-life patterns of male and female physicians. Specifically, the congruence of individual values with values inherent in the health care system appeared to be of greater consequence for women than for men. PMID:20008605

  15. Correlation of Decimetric Radio Emission and Hard X-rays in Solar Flares

    NASA Astrophysics Data System (ADS)

    Dabrowski, B.; Benz, A. O.

    2008-09-01

    The emission of decimetric radiation, in particular narrowband spikes and pulsations, is generally considered to originate from particle acceleration processes in solar flares. On the other hand, non-thermal hard X-rays are well accepted results of such acceleration. Are radio emissions and hard X-rays signatures of the same acceleration process? Good correlation of the light curves in the radio and HXR range may evidence it. The correlation of decimetric radio emission and hard X-rays in solar flares was analyzed using data from the RHESSI spacecraft and the Phoenix-2 spectrometer of ETH Zürich. The Phoenix-2 spectrometer in Bleien (Switzerland) records the solar radio emission from 100 MHz to 4 GHz. We found 169 well observed joint decimetric events in the complete list of observations from February 2002 (date launch of the RHESSI satellite) to December 2006. About hundred radio events were of the type of pulsations, and in around thirty events we found were spikes. For the detailed analysis, 33 groups (26 radio events) of pulsations and 12 groups (11 radio events) of spikes were chosen. The delay between the radio and hard X-rays emission was determined by cross-correlation. The time profiles of X-ray and radio emission differ much in energy and frequency. Thus correlation is not simply a yes/no question, but must be systematically searched in various ranges. The high spectral resolution of RHESSI made it possible to carefully choose the energy range, excluding thermal emission. The broad bandwidth of Phoenix-2 allowed selecting any emission in the full decimeter range. The energy range and duration in hard X-rays, and the frequency range in radio spectrograms were chosen to optimize the correlation. The cross-correlation coefficient was then analyzed by Gauss fit in delay for each event. The mean delay for pulsations evaluated from Gauss fitting was found to be -1.50 seconds (minus indicates that hard X-rays emission comes first). The mean delay for narrowband spikes evaluated from Gauss fitting amounts to -2.25 seconds. The delays do not depend on position on the disk, duration of the correlating sequence and maximum value of cross-correlation coefficient. However, we find an increase in delay for the spikes with GOES magnitude (peak soft X-ray emission) of the flare and with peak hard X-ray flux. This was not the case for pulsations.

  16. Microstructural characterization and hardness properties of electric resistance welding titanium joints for dental applications.

    PubMed

    Ceschini, Lorella; Boromei, Iuri; Morri, Alessandro; Nardi, Diego; Sighinolfi, Gianluca; Degidi, Marco

    2015-06-01

    The electric resistance welding procedure is used to join a titanium bar with specific implant abutments in order to produce a framework directly in the oral cavity of the patient. This investigation studied the effects of the welding process on microstructure and hardness properties of commercially pure (CP2 and CP4) Ti components. Different welding powers and cooling procedures were applied to bars and abutments, normally used to produce the framework, in order to simulate the clinical intraoral welding procedure. The analyses highlighted that the joining process did not induce appreciable changes in the geometry of the abutments. However, because of unavoidable microstructural modifications in the welded zones, the hardness decreased to values lower than those of the unwelded CP2 and CP4 Ti grades, irrespective of the welding environments and parameters. PMID:26045042

  17. Elastic moduli of a perfect hard disc crystal in two dimensions

    NASA Astrophysics Data System (ADS)

    Wojciechowski, K. W.; Brańka, A. C.

    1989-01-01

    The second order elastic moduli λ1 ≡ λξηξη and λ2 ≡ λξξηη of a perfect two-dimensional (2D) hard disk crystal are determined by the constant thermodynamic tension Monte Carlo method. The elastic moduli show the free-volume-like density dependence, λ 1 ∝ ( {ρ 0}/{ρ-1}) -2, where ρ 0 is the density at close packing, and prove to be close to those for hexagonal planes of the three-dimensional (3D) fcc and hcp crystals of hard spheres. The Kosterlitz-Thouless, Halperin-Nelson, and Young elastic constant is estimated to approach the universal value 16π in the phase coexistence region of the system.

  18. Clusters in sedimentation equilibrium for an experimental hard-sphere-plus-dipolar Brownian colloidal system

    PubMed Central

    Newman, Hugh D.; Yethiraj, Anand

    2015-01-01

    In this work, we use structure and dynamics in sedimentation equilibrium, in the presence of gravity, to examine, via confocal microscopy, a Brownian colloidal system in the presence of an external electric field. The zero field equation of state (EOS) is hard sphere without any re-scaling of particle size, and the hydrodynamic corrections to the long-time self-diffusion coefficient are quantitatively consistent with the expected value for hard spheres. Care is taken to ensure that both the dimensionless gravitational energy, which is equivalent to a Peclet number Peg, and dipolar strength Λ are of order unity. In the presence of an external electric field, anisotropic chain-chain clusters form; this cluster formation manifests itself with the appearance of a plateau in the diffusion coefficient when the dimensionless dipolar strength Λ ~ 1. The structure and dynamics of this chain-chain cluster state is examined for a monodisperse system for two particle sizes. PMID:26323363

  19. Ti1-xAux Alloys: Hard Biocompatible Metals and Their Possible Applications

    NASA Astrophysics Data System (ADS)

    Svanidze, Eteri; Besara, Tiglet; Ozaydin, M. Fevzi; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Morosan, Emilia

    2015-03-01

    The search for new hard materials is often challenging from both theoretical and experimental points of view. Furthermore, using materials for biomedical applications calls for alloys with high biocompatibility which are even more sparse. The Ti1-xAux (0 . 22 <= x <= 0 . 8) exhibit extreme hardness and strength values, elevated melting temperatures (compared to those of constituent elements), reduced density compared to Au, high malleability, bulk metallicity, high biocompatibility, low wear, reduced friction, potentially high radio opacity, as well as osseointegration. All these properties render the Ti1-xAux alloys particularly useful for orthopedic, dental, and prosthetic applications, where they could be used as both permanent and temporary components. Additionally, the ability of Ti1-xAux alloys to adhere to ceramic parts could reduce the weight and cost of these components. The work at Rice was supported by NSF DMR 0847681 (E.M. and E.S.).

  20. Clusters in sedimentation equilibrium for an experimental hard-sphere-plus-dipolar Brownian colloidal system.

    PubMed

    Newman, Hugh D; Yethiraj, Anand

    2015-01-01

    In this work, we use structure and dynamics in sedimentation equilibrium, in the presence of gravity, to examine, via confocal microscopy, a Brownian colloidal system in the presence of an external electric field. The zero field equation of state (EOS) is hard sphere without any re-scaling of particle size, and the hydrodynamic corrections to the long-time self-diffusion coefficient are quantitatively consistent with the expected value for hard spheres. Care is taken to ensure that both the dimensionless gravitational energy, which is equivalent to a Peclet number Peg, and dipolar strength Λ are of order unity. In the presence of an external electric field, anisotropic chain-chain clusters form; this cluster formation manifests itself with the appearance of a plateau in the diffusion coefficient when the dimensionless dipolar strength Λ ~ 1. The structure and dynamics of this chain-chain cluster state is examined for a monodisperse system for two particle sizes. PMID:26323363

  1. Lessons of Diversity Learned the Hard Way

    ERIC Educational Resources Information Center

    Morrison, Kathy

    2009-01-01

    Through experiences training teachers across the country, the author gains insight into the necessity to accommodate diverse Native American learners. Sensitivity to Native American learning styles and values enables the author to better meet individual needs and learn valuable lessons in diversity. The author tells the story of her experiences…

  2. Does the temperature of beverages affect the surface roughness, hardness, and color stability of a composite resin?

    PubMed Central

    Tuncer, Duygu; Karaman, Emel; Firat, Esra

    2013-01-01

    Objective: To investigate the effect of beverages’ temperature on the surface roughness, hardness, and color stability of a composite resin. Materials and Methods: Fifty specimens of the Filtek Z250 composite (3M ESPE, Dental Products, St.Paul, MN, USA) were prepared and initial roughness, microhardness, and color were measured. Then the specimens were randomly divided into five groups of 10 specimens each: Coffee at 70°C, coffee at 37°C, cola at 10°C, cola at 37°C, and artificial saliva (control). After the samples were subjected to 15 min × 3 cycles per day of exposure to the solutions for 30 days, the final measurements were recorded. Results: After immersion in beverages, the artificial saliva group showed hardness values higher than those of the other groups (P < 0.001) and the microhardness values were significantly different from the initial values in all groups except for the control group. Both cola groups showed roughness values higher than the baseline values (P < 0.05), while the other groups showed values similar to the baseline measurements. When ΔE measurements were examined, the 70°C coffee group showed the highest color change among all the groups (P < 0.05). Conclusion: High-temperature solutions caused alterations in certain properties of composites, such as increased color change, although they did not affect the hardness or roughness of the composite resin material tested. PMID:24883021

  3. Size Effects in Nano-phase Hard Magnetic Materials

    NASA Astrophysics Data System (ADS)

    Akdogan, Ozan

    This dissertation work was focused on the behavior of the hard magnetic materials in the nano-size and under confinement in special geometries. Three distinct systems have been examined carefully to see the effects of nano dimensions on the intrinsic and hard magnetic properties of these materials, namely Alnico thin films, Sm-Co and FePt nanoparticles. In our research work to study the spinodal decomposition of Alnico thin films prepared by sputtering on Si substrates, it has been discovered that Si diffuses into the films and gives rise to a new magnetically hard phase with TC=305°C. The phase formation occurs following the annealing at 900°C, which gave a room temperature coercivity 6.5 kOe. The maximum coercivity observed is approximately ten times larger than the bulk Alnico V value. The aim of the second project was to synthesize Sm-Co nanoparticles with high HC in the as-made state. During RT synthesis, 3.5 nm superparamagnetic SmCo5 nanoparticles have been successfully produced via the Cluster Beam Deposition (CBD) technique. Dispersion of the SmCo5 nanoparticles in a carbon matrix resulted in increase in both the coercivity and the blocking temperature. Room temperature coercivities as high as 12 kOe have been obtained for the first time in mono-layers of SmCo5 nanoparticles dispersed in C matrix. δM plots showed that the interactions in the sample with closed packed particles are of exchange type, which lead to a decrease the overall effective anisotropy and coercivity according to the random-anisotropy model. For the third project of this dissertation, single crystal FCT FePt nanocubes have been successfully produced by a CBD technique without the need of post annealing. The nanocubes have a uniform size distribution with an average size of 6.5 nm. At 1 Torr, the particles have the FCT structure with an order parameter of 0.5 and a RT coercivity of 2 kOe. Further annealing increased the particle size to 20 nm and the RT coercivity to 10.2 kOe with perfect chemical ordering. In addition to these nanocubes, micron size rods with the FCT structure have been observed near the cluster gun. SEM analysis showed that these rods consist of nanoparticles with 20 nm average size. The new phase formation in the Alnico systems is important in view of the recent "rare earth problem" and may lead to alternative to rare earth materials for the development of high performance magnets. FePt and SmCo5 nanoparticles have a potential for use in the development of future high-density magnetic recording media because of their high coercivity, good shape and very narrow size distribution.

  4. Enhancing the hardness of Al/W nanostructured coatings

    NASA Astrophysics Data System (ADS)

    Burgmann, F. A.; McCulloch, D. G.; Ryves, L.; Lim, S. H. N.; McKenzie, D. R.; Bilek, M. M. M.

    2009-02-01

    Two-component multilayer thin films frequently show hardness enhancements at specific repeat periods above that of the constituent layers. This study of hardness enhancements in W/Al nanostructured coatings provides strong new evidence that hardness enhancements in this system arise not only from the presence of a layered structure, but also from the presence of defects introduced by changing the deposition conditions. Samples with well defined layers of W and Al were produced by sputtering to cover a wide range of periods from 10 to 200 nm. No evidence of enhanced hardness in these films was found by nanoindentation. On the other hand, samples deposited from cathodic arc sources showed strong hardness enhancement above that of pure W. However, the samples of highest hardness did not contain Al layers for much of their thickness. The hardening mechanism therefore could not be attributed to the presence of a multilayer structure. Examination of the microstructure showed that the interruptions to the W deposition caused by operation of the Al source introduced defects which acted as pinning sites for dislocations. The nanoindentation hardness data were well described using a modified Hall-Petch relation.

  5. Low hardness organisms: Culture methods, sensitivities, and practical applications

    SciTech Connect

    DaCruz, A.; DaCruz, N.; Bird, M.

    1995-12-31

    EPA Regulations require biomonitoring of permitted effluent and stormwater runoff. Several permit locations were studied, in Virginia, that have supply water and or stormwater runoff which ranges in hardness from 5--30 mg/L. Ceriodaphnia dubia (dubia) and Pimephales promelas (fathead minnow) were tested in reconstituted water with hardnesses from 5--30 mg/L. Results indicated osmotic stresses present in the acute tests with the fathead minnow as well as chronic tests for the dubia and the fathead minnow. Culture methods were developed for both organism types in soft (30 mg) reconstituted freshwater. Reproductivity and development for each organisms type meets or exceeds EPA testing requirements for moderately hard organisms. Sensitivities were measured over an 18 month interval using cadmium chloride as a reference toxicant. Additionally, sensitivities were charted in contrast with those of organisms cultured in moderately hard water. The comparison proved that the sensitivities of both the dubia and the fathead minnow cultured in 30 mg water increased, but were within two standard deviations of the organism sensitivities of those cultured in moderately hard water. Latitude for use of organisms cultured in 30 mg was documented for waters ranging in hardness from 10--100 mg/L with no acclimation period required. The stability of the organism sensitivity was also validated. The application was most helpful in stormwater runoff and in effluents where the hardness was 30 mg/L or less.

  6. The uptake of water hardness metals by human hair.

    PubMed

    Evans, A O; Marsh, J M; Wickett, R R

    2011-01-01

    The objective of this work was to examine the variables that influence the interaction between water hardness metals and human hair. Hair extracts various constituents from the tap water used during daily hygiene practices and chemical treatments. Calcium and magnesium metal ions are the most prevalent and give water "hardness." Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was employed to quantify the metal content of hair, which was studied as a function of the following variables: hair condition (oxidative damage), level of water hardness, and water pH. We have demonstrated that these variables impact water hardness metal uptake to varying extents, and the effects are driven primarily by the binding capacity (available anionic sites) of the hair. The condition of the hair, a key representation of the binding capacity, was most influential. Interestingly, water hardness levels had only a small effect on uptake; hair became saturated with notable amounts of water hardness metals even after repeated exposure to soft water. Water pH influenced metal uptake since side chains of hair proteins deprotonate with increasing alkalinity. These insights highlight the importance to the hair care industry of understanding the interaction between water hardness metals and hair. PMID:21982353

  7. Introduction to Hard Scattering Processes and Recent Results from Hard Probes at RHIC and LHC

    NASA Astrophysics Data System (ADS)

    Harris, John W.

    2015-07-01

    A summary is presented of recent heavy-ion collision results from hard scattering processes at RHIC and LHC. Hadrons with large transverse momentum are suppressed in heavy- ion collisions compared to proton-proton interactions, including those hadrons with heavy quarks (charm, beauty). Jets are quenched and modifications to their fragmentation are observed, the effects increasing with the centrality of the heavy-ion collision. The heavy-ion measurements are compared to those in proton-proton and proton-nucleus collisions. These results when compared to theory are consistent with the suppression and jet quenching being a product of parton energy loss in a hot QCD medium. Correlations are presented for di-jets, jets with trigger photons, and hadrons with trigger jets. The di-jet correlations exhibit a di-jet energy and momentum imbalance that increases with the centrality of the collision. The correlation results indicate that the parton energy loss is redistributed to lower momentum particles at larger angles from the axis of the hard-scattered parton.

  8. Do We Value Caring?

    ERIC Educational Resources Information Center

    Weissbourd, Richard; Anderson, Trisha Ross

    2016-01-01

    When asked about their child-rearing priorities, parents in the United States are likely to say it's more important to raise children who are caring than to raise high achievers. Schools, too, typically trumpet values such as caring, honesty, and fairness. These values are posted on walls, reiterated in assemblies, and included in mission…

  9. Sustaining NCTE Values

    ERIC Educational Resources Information Center

    Logan, Shirley Wilson

    2011-01-01

    NCTE's core values, posted on the website (http://www.ncte.org), are writing, literature, diversity, integrated language arts, knowledgeable and caring teachers, advocacy, and public education ("NCTE Core Values"). In this article, the author focuses only on writing, diversity, and advocacy, considering just a few ways in which the organization…

  10. Art's Educational Value

    ERIC Educational Resources Information Center

    Richmond, Stuart

    2009-01-01

    This paper explores critically the nature of art's value in education and argues in favor of both intrinsic and instrumental value. Form and expression, while being out of favor in some contemporary circles, are re-claimed as appropriate features of art. Concepts and forms in art as elsewhere serve to structure impressions and experience and…

  11. High coking value pitch

    SciTech Connect

    Miller, Douglas J.; Chang, Ching-Feng; Lewis, Irwin C.; Lewis, Richard T.

    2014-06-10

    A high coking value pitch prepared from coal tar distillate and has a low softening point and a high carbon value while containing substantially no quinoline insolubles is disclosed. The pitch can be used as an impregnant or binder for producing carbon and graphite articles.

  12. Understanding Place Value

    ERIC Educational Resources Information Center

    Cooper, Linda L.; Tomayko, Ming C.

    2011-01-01

    Developing an understanding of place value and the base-ten number system is considered a fundamental goal of the early primary grades. For years, teachers have anecdotally reported that students struggle with place-value concepts. Among the common errors cited are misreading such numbers as 26 and 62 by seeing them as identical in meaning,…

  13. Cognitive and Social Values.

    ERIC Educational Resources Information Center

    Machamer, Peter; Douglas, Heather

    1999-01-01

    Criticizes Hugh Lacey's separation of cognitive values and social values in discussions of the nature of science. Claims that attempting to distinguish between cognitive and social ignores crucial complexities in the development and use of knowledge. Proposes that the proper distinction be between legitimate and illegitimate reasons in science as…

  14. Dance: Verities, Values, Visions.

    ERIC Educational Resources Information Center

    Boorman, Joyce, Ed.; Harris, Dorothy, Ed.

    The Binational Dance Conference was organized into three focal themes--verities, values, and visions in dance--to emphasize the known and accepted worth and value of dance, and to stimulate through knowledge and idea exchange, imaginative directions for dance in the future of both the United States and Canada. This thematic structure is also the…

  15. Rosenak "Teaching Jewish Values"

    ERIC Educational Resources Information Center

    Resnick, David

    2014-01-01

    Rosenak's "Teaching Jewish Values" (1986) is perhaps his most accessible book about Jewish education. After diagnosing the "diseases" of Jewish education, he endorses "teaching Jewish values" as the curricular strategy most likely to succeed given the chasm which divides traditional Jewish subject matter and the…

  16. Ecology and Human Values.

    ERIC Educational Resources Information Center

    1970

    "Ecology and Human Values" is an interdisciplinary course designed for senior year high school students in social studies and/or science. Its main thrust is the investigation of human values as they relate to the environment, although rooted in the natural sciences as a means of understanding the complexities inherent in the environment. Use is…

  17. How I Taught Values

    ERIC Educational Resources Information Center

    Pratt, Annis

    2005-01-01

    Values are principles or standards that people have decided are desirable to live by. The question of whether values can or should be taught to college students has been debated for decades, with the pros incorporating moral concepts into curricula and the antes scorning such efforts as not only inappropriate but also intellectually dull. In this

  18. Work Values across Generations

    ERIC Educational Resources Information Center

    Hansen, Jo-Ida C.; Leuty, Melanie E.

    2012-01-01

    Mainstream publication discussions of differences in generational cohorts in the workplace suggest that individuals of more recent generations, such as Generation X and Y, have different work values than do individuals of the Silent and Baby Boom generations. Although extant research suggests that age may influence work values, few of the

  19. Management Values Survey Results.

    ERIC Educational Resources Information Center

    Duffy, Barbara; Payne, Ron

    1988-01-01

    Describes results of a survey conducted to compare values of members of the Association for Educational Communications and Technology (AECT) with managers in business and industry. Issues discussed include job satisfaction, opportunities for advancement, attitudes toward management, and salary; a summary of each value system is provided. (LRW)

  20. Teaching Values through Drama.

    ERIC Educational Resources Information Center

    Berghammer, Gretta

    One dramatic technique to aid students in their discovery of values and value systems is "theatre-in-education" (TIE), a theatre event that takes place in schools, with actors working through roles for and with children. TIE aims to fuse education and theatre by having team members function as both teachers and actors, and the audiences of young…

  1. Work Values across Generations

    ERIC Educational Resources Information Center

    Hansen, Jo-Ida C.; Leuty, Melanie E.

    2012-01-01

    Mainstream publication discussions of differences in generational cohorts in the workplace suggest that individuals of more recent generations, such as Generation X and Y, have different work values than do individuals of the Silent and Baby Boom generations. Although extant research suggests that age may influence work values, few of the…

  2. Characterization and hardness of TiCu–Ti2Cu3 intermetallic material fabricated by mechanical alloying and subsequent annealing

    NASA Astrophysics Data System (ADS)

    Akbarpour, Mohammad Reza; Alikhani Hesari, Feridoun

    2016-04-01

    In this research, the microstructural and phase evolutions during mechanical alloying (MA) and subsequent heat treatment of Cu–Ti powder mixture are investigated through x-ray diffraction, scanning electron microscopy, transmission electron microscopy and micro-hardness measurements. The obtained experimental results demonstrated that after an optimum MA time of 30 h, TiCu intermetallic compound was achieved with a mean grain size of ≈8 nm and a high micro-hardness value of ≈634 Hv. Annealing the milled powder at different temperatures resulted in formation of major TiCu and Ti2Cu3, and minor Ti2Cu and Cu4Ti nanocrystalline phases, release of internal strain, and coarsening of grains. The amount of TiCu phase and the grain size increased with increase of the annealing temperature. Micro-hardness value of ≈765 Hv was recorded when the milled TiCu powder was annealed at 850 °C. This superior high micro-hardness value can be attributed to formation of higher amount of TiCu phase.

  3. 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 part in the AEHRL program. The paper concludes the results from the stage goals 1 and 2, and presents the projects conducted within the stage goals 3 and 4 as well as conclusions drawn from available results.

  4. Connection between micro and macro hardness pearlitic-ferritic steel

    NASA Astrophysics Data System (ADS)

    Duka, Edlira; Oettel, Heinrich; Dilo, Teuta

    2012-09-01

    Many physical and mechanical properties of materials are closely related to their microstructure, technologies to control the microstructure of materials have been well developed to obtain suitable properties. We measured the volume fraction of perlite and ferrite, micro Vickers hardness in pearlite and ferrite and macro hardness using different sample with different carbon content. The volume fraction of pearlite increases by increasing carbon content. By increasing carbon content, micro and macro hardness increase. We can conclude that for those conditional the mixing rule can't be use.

  5. Cr-based bulk metallic glasses with ultrahigh hardness

    NASA Astrophysics Data System (ADS)

    Si, J. J.; Wang, T.; Wu, Y. D.; Cai, Y. H.; Chen, X. H.; Wang, W. Y.; Liu, Z. K.; Hui, X. D.

    2015-06-01

    This letter reports quaternary Cr-Co-Nb-B bulk metallic glasses (BMGs) with ultrahigh hardness and Young's moduli. Especially, Cr55Co24Nb7B14 BMG exhibits ultrahigh Vickers hardness and Young's modulus of 1605 and 278 GPa, respectively, and the highest specific Young's modulus of 37.0 × 106 N m/kg among all the developed BMGs so far. It is considered that the high hardness and Young's moduli for this kind of BMGs are intrinsically attributed to the strong interactions between metallic constituent elements and B.

  6. 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.

  7. Model for magnetostrictive performance in soft/hard coupled bilayers

    NASA Astrophysics Data System (ADS)

    Jianjun, Li; Beibei, Duan; Minglun, Li

    2015-11-01

    A model is set up to investigate the magnetostrictive performance and spin response in soft/hard magnetostrictive coupled bilayers. Direct coupling between soft ferromagnet and hard TbFe2 at the interface is assumed. The magnetostriction results from the rotation of ferromagnetic vector and TbFe2 vectors from the easy axis driven by applied magnetic field. Dependence of magnetostriction on TbFe2 layer thickness and interfacial exchange interaction is studied. The simulated results reveal the compromise between interfacial exchange interaction and anisotropy of TbFe2 hard layer.

  8. Compressibility and hardness of Co-based bulk metallic glass: A combined experimental and density functional theory study

    SciTech Connect

    Wang Jianfeng; Li Ran; Xu Tao; Li Yan; Liu Zengqian; Huang Lu; Hua Nengbin; Zhang Tao; Xiao Ruijuan; Li Gong; Li Yanchun

    2011-10-10

    An incompressible Co{sub 54}Ta{sub 11}B{sub 35} bulk metallic glass (BMG) was investigated using in situ high-pressure synchrotron diffraction and nanoindendation. The elastic constants were deduced from the experiments based on the isotropic model. The Vickers hardness was measured to be 17.1 GPa. The elastic moduli and hardness are the highest values known in BMGs. The theoretically calculated elastic properties by density-functional study were well consistent with experimental measurements. The analysis of charge density and bonding character indicates the covalent character of Co-B and B-B bonds, underlying the unusually high elastic modulus and hardness in this material.

  9. Spectral evolution of gamma-ray bursts detected by the SIGNE experiment. 1: Correlation between intensity and spectral hardness

    NASA Technical Reports Server (NTRS)

    Kargatis, Vincent E.; Liang, Edison P.; Hurley, Kevin C.; Barat, C.; Eveno, E.; Niel, M.

    1994-01-01

    We study the continuum spectral evolution of 16 gamma-ray bursts detected by the Franco-Soviet SIGNE experiment in 1981-1982 by fitting time resolved (0.5 s) spectra in count space with simple thermal bremsstrahlung and synchrotron models. We find that there is no single characteristic of spectral evolution: we see hard-to-soft, soft-to-hard, luminosity-hardness tracking, and chaotic evolution. We perform correlation studies between instantaneous burst intensity and spectral temperature for seven bursts. While we basically confirm the existence of a correlation between these variables as originally claimed by Golenetskii et al. (1983) we find higher values and a broader range of correlation indices.

  10. Hardness, Microstructure, and Residual Stresses in Low Carbon Steel Welding with Post-weld Heat Treatment and Temper Bead Welding

    NASA Astrophysics Data System (ADS)

    Aloraier, Abdulkareem S.; Joshi, Suraj; Price, John W. H.; Alawadhi, Khaled

    2014-04-01

    This paper investigates the effects of post-weld heat treatment (PWHT) and temper bead welding (TBW) on hardness, microstructure and residual stresses in multi-layer welding on low carbon steel specimens made with two different weld geometries, viz. (1) smooth-contoured and (2) U-shaped. It was found that the PWHT technique gave overall lower hardness than the TBW technique, but the hardness values in both techniques were acceptable. Microscopy analysis showed that the TBW technique was more effective in tempering the heat affected zone as the grain size decreased slightly at the fusion line in spite of the higher temperature at the fusion line. Residual stresses measured using the hole-drilling method showed that the residual stress is not reduced below yield stress near the last bead solidified in TBW. Only PWHT gives low residual stress results in this area. High tensile residual stresses may result in sensitivity to fatigue loading.

  11. Gross Morphometric Studies on the Tongue, Buccal Cavity and Hard Palate of the Fruit Bat (Eidolon helvum).

    PubMed

    Igado, O O; Omobowale, T O; Ajadi, R A; Nottidge, H O

    2015-08-01

    This study was designed to assess the gross morphometric studies of the tongue, hard palate and buccal cavity of the fruit bat (Eidolon helvum). Sixty bats of both sexes were used for this study. The tongue was excised, and the weight and various linear measurements were determined. Linear measurements were also determined on the hard palate. The gross distribution of the lingual papillae was observed to be the same in both sexes; values obtained for the weight and length of the tongue were higher in the females, although no statistically significant differences were observed (P > 0.05). The number of ridges on the hard palate displayed sexual dimorphism. Results obtained from this study may find application in the field of comparative and clinical anatomy of wildlife and also in feeding physiology. PMID:25115593

  12. Formation of hard surface layer on austenitic stainless steels via simultaneous chromising and nitriding by pack cementation process

    NASA Astrophysics Data System (ADS)

    Zeng, D.; Yang, S.; Xiang, Z. D.

    2012-04-01

    This study aims to increase surface hardness of austenitic stainless steels via simultaneous chromising and nitriding by the pack cementation process. The pack powder mixtures used for the process consisted of Cr2N as a source of both N and Cr for the simultaneous process, NH4Cl as activator and Al2O3 as inert filler; in some cases, Cr powder was added as an additional source for depositing Cr. The AISI204 austenitic stainless steel is studied as a substrate. It is demonstrated that a top Cr2N layer with a Cr enriched layer underneath can be formed on the steel surface at 1100 °C. Hardness values of more than 1800 HV are obtained at the outermost surface of the treated specimen. It has been shown that the hardness profile at the cross-section of the surface depends on the pack chemistry.

  13. Elasticity of two-dimensional crystals of polydisperse hard disks near close packing: Surprising behavior of the Poisson's ratio

    NASA Astrophysics Data System (ADS)

    Tretiakov, Konstantin V.; Wojciechowski, Krzysztof W.

    2012-05-01

    The equation of state, elastic constants, and Poisson's ratio of a crystalline two-dimensional polydisperse hard disk system were determined in the close packing limit. Monte Carlo simulations in the NpT ensemble with variable shape of the periodic box reveal that the pressure and elastic constants grow with increasing polydispersity. The equation of state and the bulk modulus are well described by the free volume approximation. The latter approximation fails, however, for the shear modulus. The simulations also show that the introduction of any amount of size polydispersity in the hard disk systems causes a discontinuous "jump" of the Poisson's ratio in the close packing limit from the value νδ=0 = 0.1308(22), obtained for equidiameter hard disks, to νδ>0 ≈ 1, estimated for the polydisperse disks.

  14. Vicker's hardness and Raman spectroscopy evaluation of a dental composite cured by an argon laser and a halogen lamp.

    PubMed

    Soares, Lus Eduardo Silva; Martin, Airton Abraho; Pinheiro, Antonio Luiz Barbosa; Pacheco, Marcos T T

    2004-01-01

    We present the results of the Vicker's hardness test and the use of near-infrared Raman spectroscopy (RS) to measure in vitro the degree of conversion (DC) of a bis(phenol)-A-glycidyl-dimethacrylate-based composite resin, photoactivated by both a halogen lamp (power density=478 mW/cm(2); 8-mm diameter spot) and an argon laser (power density=625 mW/cm(2); 7-mm diameter spot). The degree of conversion was estimated by analyzing the relative intensities between the aromatic C=C stretching Raman mode at 1610 cm(-1) and the methacrylate C=C stretching Raman mode (1640 cm(-1)) on top and bottom surfaces. For the hardness evaluation, the samples were embedded in polyester resin and three indentations with a 50-g load for 10 s were made on the top surface. The higher relative DC values achieved by the photoactivation of a composite resin by the argon laser suggest a better biocompatibility in the bottom surface. The correlation test showed that the higher Vicker's hardness number (VHN) values were associated with higher DC values. The derivative analysis showed a greater curing rate from 5 to 20 s of exposure. The comparison of VHN and DC values with both light sources at each curing time showed that a small change in conversion is related to a large change in hardness. Raman spectroscopy is more sensitive to changes in the first stages of curing reaction than later ones, and the Vicker's hardness assay is more sensitive to changes in the last stages. PMID:15189099

  15. Assessing spatial trends of cultural stone weathering intensity using a hardness tester: The case of Manglieu Saint-Sébastien church (France)

    NASA Astrophysics Data System (ADS)

    Roussel, Erwan; Gruson, Soizic; Vautier, Franck; Voldoire, Olivier; André, Marie-Françoise

    2014-05-01

    In heritage science, the quantitative assessment of rock hardness is of primary interest to characterize the degree of weathering of a cultural stone. Modern hardness testers are non-destructive and can be used on cultural heritage materials to collect repeated measurements of rock strength without causing damage. Furthermore, the development of portable solutions such as the Equotip Piccolo 2 facilitates the in situ hardness survey of a whole façade of a monument. It allows to address the question of spatial variability of weathering intensity within a monument, and the mapping of hardness values can reveal strong gradients or discontinuities in stone decay induced by restoration operations. The present study deals with the spatial distribution of stone hardness on the façade of the Saint-Sébastien Romanesque abbey church at Manglieu, in the French Massif Central. It was built during the twelfth century and listed as a protected historic monument in 1840. During the Late 19th century, the lower part of the west-facing wall was restored and the original gneissic material was replaced by granitic ashlars. Since this operation, an intense deterioration has affected the original gneissic stones overlying the granitic base of the wall. Our objective is to quantitatively assess the effect of this restoration on the current spatial trends of the gneiss hardness. Rock strength values were collected using the portable hardness tester Equotip Piccolo 2, and the spatial distribution was investigated at two scales: (i) At the portal scale, the hardness values of all stones were measured based on 30 values per stone; (ii) At the stone scale, a systematic sampling method was performed on two gneissic ashlars in order to collect hardness values over a grid of 9 cm resolution. On each sample, the repeated impact method was performed: 20 consecutive measurements at the same location were collected in order to reconstruct the spatial variation of weathering degree within the stone surface. At the portal scale, the results indicate an inverse correlation between the weathering intensity of gneissic stones and the vertical distance to the granitic ashlars, suggesting the deleterious effects of the water capillary rise enhanced by the incorporation of low porosity granite at the base of the wall. At the stone scale, the weathering maps display a strong spatial autocorrelation of hardness values, suggesting a gradual diffusive process of weathering within the stones.

  16. Value of Information References

    DOE Data Explorer

    Morency, Christina

    2014-12-12

    This file contains a list of relevant references on value of information (VOI) in RIS format. VOI provides a quantitative analysis to evaluate the outcome of the combined technologies (seismology, hydrology, geodesy) used to monitor Brady's Geothermal Field.

  17. The Teaching of Values.

    ERIC Educational Resources Information Center

    Nugent, Gwen C.; And Others

    1980-01-01

    Described are reasons and methods for using videotapes to incorporate value-based issues (i.e., honesty, consequences of research, professional responsibility) into college physical science class discussions. (CS)

  18. Working with Missing Values

    ERIC Educational Resources Information Center

    Acock, Alan C.

    2005-01-01

    Less than optimum strategies for missing values can produce biased estimates, distorted statistical power, and invalid conclusions. After reviewing traditional approaches (listwise, pairwise, and mean substitution), selected alternatives are covered including single imputation, multiple imputation, and full information maximum likelihood…

  19. Values in psychotherapy.

    PubMed

    Holmes, J

    1996-01-01

    There is a tension between those who hold that psychotherapy is a scientific discipline and therefore "value-free," and those who believe that values are inherent in the nature of psychotherapy. Psychoanalysis has moved from a science-based ideology, through the ethical concerns of Melanie Klein, to a recognition of the "aesthetic" dimension--the creation of suitable forms that can contain psychological distress. From this latter perspective, the antagonism between religion and psychotherapy, initiated by Freud, becomes less acute. Action-based ethical systems, which ignore the inner world, are critically scrutinized. The evidence suggesting there is a relationship between good outcome in psychotherapy and shared values between therapist and client is reviewed. It is posited that through examination of the "ethical countertransference," therapists should become aware of their own value systems and how they influence practice. PMID:8886227

  20. Remote hard copy. Volume 2. Operating manual. [Versatec 1110A

    SciTech Connect

    Simons, R.W.

    1980-03-01

    Procedures for operating the remote hard copy plotters are presented. Initializing the system, caring for the plotter, and interacting with the system are all covered. Descriptions of error conditions and how to operate diagnostics are presented.

  1. Event-driven Langevin simulations of hard spheres.

    PubMed

    Scala, A

    2012-08-01

    The blossoming of interest in colloids and nanoparticles has given renewed impulse to the study of hard-body systems. In particular, hard spheres have become a real test system for theories and experiments. It is therefore necessary to study the complex dynamics of such systems in presence of a solvent; disregarding hydrodynamic interactions, the simplest model is the Langevin equation. Unfortunately, standard algorithms for the numerical integration of the Langevin equation require that interactions are slowly varying during an integration time step. This is not the case for hard-body systems, where there is no clear-cut distinction between the correlation time of the noise and the time scale of the interactions. Starting first from a splitting of the Fokker-Plank operator associated with the Langevin dynamics, and then from an approximation of the two-body Green's function, we introduce and test two algorithms for the simulation of the Langevin dynamics of hard spheres. PMID:23005884

  2. Crystalline assembly of hard polyhedra via directional entropic forces

    NASA Astrophysics Data System (ADS)

    Damasceno, Pablo F.; Engel, Michael; Glotzer, Sharon C.

    2012-02-01

    Entropic forces are effective forces that result from a system's statistical tendency to increase its entropy. Hard rods and disks spontaneously align and can assemble into layers and columns if those structures increase the configurational space available to the particles. Hard spheres, cubes and even tetrahedra order for the same reason. Here we extend those findings by showing that hard polyhedra can self-assemble into a variety of complex phases, most of them never before reported in systems of single-component hard particles. The role of shape and directional entropic forces in stabilizing these structures will be discussed. Our results suggest new possibilities for self-assembling complex target structures from colloidal building blocks. [4pt] [1] Damasceno, PF; Engel, M; Glotzer, SC. arXiv:1109.1323v1

  3. 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 ...

  4. Letter: Ischemic heart disease, water hardness and myocardial magnesium.

    PubMed Central

    Anderson, T. W.; Neri, L. C.; Schreiber, G. B.; Talbot, F. D.; Zdrojewski, A.

    1975-01-01

    In 54 cases of accidental death in cities with water hardness of 60 parts per million (ppm) or less, the mean myocardial magnesium concentration was 918 mug/g of dry tissue. This was 7% lower than the corresponding figure of 982 mug/g among 29 cases of accidental death in cities with water hardness of 300 ppm or more, and this difference was significant (P less than 0.01). There were no significant differences between the cities with soft and hard water in the mean myocardial concentrations of calcium, zinc, copper, chromium, lead or cadmium. These results are compatible with the belief that the relatively high death rates in some soft-water areas may be due to a suboptimal intake of magnesium, and that water-borne magnesium exerts a protective effect on the residents of hard-water areas. PMID:1139518

  5. How to estimate hardness of crystals on a pocket calculator

    SciTech Connect

    Simunek, Antonin

    2007-05-01

    A generalization of the semiempirical microscopic model of hardness is presented and applied to currently studied borides, carbides, and nitrides of heavy transition metals. The hardness of OsB, OsC, OsN, PtN, RuC, RuB{sub 2}, ReB{sub 2}, OsB{sub 2}, IrN{sub 2}, PtN{sub 2}, and OsN{sub 2} crystals in various structural phases is predicted. It is found that none of the transition metal crystals is superhard, i.e., with hardness greater than 40 GPa. The presented method provides materials researchers with a practical tool in the search for new hard materials.

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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...

  11. Chemical bonding in hard boron-nitride multilayers

    SciTech Connect

    Jankowski, A.F.; Hayes, J.P.

    1997-06-01

    The oxides and nitrides of boron show great potential for use as hard, wear resistant materials. However, large intrinsic stresses and poor adhesion often accompany the hard coatings as found for the cubic boron-nitride phase. These effects may be moderated for use of a layered structure. Alternate stiff layers of boron and compliant layers of nitride are formed by modulating the sputter gas composition during deposition of boron target. The B/BN thin films are characterized with transmission electronic microscope to evaluate the microstructure, nanoindentation to measure hardness and ex-ray absorption spectroscopy to determine chemical bonding. The effects of layer pair spacing on chemical bonding and hardness are evaluated for the B/BN films.

  12. 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...

  13. Collective excitations in 2D hard-disc fluid.

    PubMed

    Huerta, Adrian; Bryk, Taras; Trokhymchuk, Andrij

    2015-07-01

    Collective dynamics of a two-dimensional (2D) hard-disc fluid was studied by molecular dynamics simulations in the range of packing fractions that covers states up to the freezing. Some striking features concerning collective excitations in this system were observed. In particular, the short-wavelength shear waves while being absent at low packing fractions were observed in the range of high packing fractions, just before the freezing transition in a 2D hard-disc fluid. In contrast, the so-called "positive sound dispersion" typically observed in dense Lennard-Jones-like fluids, was not detected for the 2D hard-disc fluid. The ratio of specific heats in the 2D hard-disc fluid shows a monotonic increase with density approaching the freezing, resembling in this way the similar behavior in the vicinity of the Widom line in the case of supercritical fluids. PMID:25595625

  14. 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 use of antiferromagnetically coupled soft underlayers and soft underlayers that are exchange coupled with an antiferromagnetic layer. Significant improvements have also been made in the head design. All these factors now make perpendicular recording more competitive. It is expected that the current materials could theoretically support areal densities of up to 500-600Gbits/in.2. In this paper, the technologies associated with perpendicular recording media are reviewed. A brief background of magnetic recording and the challenges faced by longitudinal recording technology are presented first, followed by the discussions on perpendicular recording media. Detailed discussions on various layers in the perpendicular recording media and the recent advances in these layers have been made. Some of the future technologies that might help the industry beyond the conventional perpendicular recording technology are discussed at the end of the paper.

  15. 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 the structure and the self-diffusion. We discuss the relevance of our results to the glass transition in hard ellipses. Finally, the results of the isodiffusivity lines are evaluated for hard ellipses and we discuss the effect of spatial dimension on the diffusive dynamics of hard ellipsoidal particles. PMID:23862947

  16. Approximate resolution of hard numbering problems

    SciTech Connect

    Bailleux, O.; Chabrier, J.J.

    1996-12-31

    We present a new method for estimating the number of solutions of constraint satisfaction problems. We use a stochastic forward checking algorithm for drawing a sample of paths from a search tree. With this sample, we compute two values related to the number of solutions of a CSP instance. First, an unbiased estimate, second, a lower bound with an arbitrary low error probability. We will describe applications to the Boolean Satisfiability problem and the Queens problem. We shall give some experimental results for these problems.

  17. Spark alloying of an AL9 alloy by hard alloys

    NASA Astrophysics Data System (ADS)

    Kuptsov, S. G.; Fominykh, M. V.; Mukhinov, D. V.; Magomedova, R. S.; Nikonenko, E. A.

    2015-08-01

    The phase compositions of spark coatings of Kh12M steel with a VT1-0 (titanium) alloy and T15K6 and T30K4 hard alloys are studied. It is shown that the TiC titanium carbide forms in all cases and tungsten carbide decomposes with the formation of tungsten in a coating. These processes are intensified by increasing time, capacitance, and frequency. The surface hardness, the sample weight, and the white layer thickness increase monotonically.

  18. The hard sphere view of the outer core

    NASA Astrophysics Data System (ADS)

    Helffrich, George

    2015-12-01

    The hard sphere model for liquids attempts to capture the physical behavior of a real liquid in a simple conceptual model: a fluid of fixed size spheres that only interact repulsively when they come into contact. Is the model good enough to use for modeling internal planetary structure? To answer this question, I survey variants of hard sphere liquid theory by applying them to the Earth's outer core to determine which of them explains wavespeeds in the outer core best. The variants explored here are the Carnahan-Starling hard sphere model, the Mansoori-Canfield extension to hard sphere mixtures, the transition metal hard sphere liquid, and the Lennard-Jones hard sphere liquid with attractive forces. With an empirical addition of a temperature dependence to the liquid's hard sphere diameter, all of the variants explored can replicate wavespeeds in most of the radius range of the outer core. The hard sphere model for liquid transition metals explains the wavespeed best because it yields a mean liquid atomic weight of 48.8 g mo l -1 at 10 wt% light element abundance in the core which is in good cosmochemical agreement with core light element models. Other variants also fit core wavespeeds but require implausibly low liquid mean atomic weight implying excessive incorporation of hydrogen or helium in the core. Applied to the detailed wavespeed structure of the Earth's outermost outer core, the model suggests that the mean atomic weight could be reduced by up to 1.74% or the temperature could be increased by up to 400 K relative to an adiabatic profile, or there could be 8% fewer valence electrons in the liquid.

  19. Hard exclusive reactions and generalized parton distributions at HERMES

    NASA Astrophysics Data System (ADS)

    Düren, M.; Hermes Collaboration

    2009-06-01

    The concept of generalized parton distributions is discussed and applied to hard exclusive reactions at the HERMES experiment at DESY. Recent results on hard exclusive meson production and in particular on deeply virtual Compton scattering are presented. For the first time, information about the orbital angular momentum of quarks in the nucleon can be extracted from experiment. Using a new detector for recoil particles, HERMES will be able to give even more complete results in future.

  20. Marine plastic litter as an artificial hard bottom fouling ground

    NASA Astrophysics Data System (ADS)

    Harms, J.

    1990-09-01

    20 fouling organisms were observed on plastic litter dredged from the Elbe estuary during July 1990; 60% of the species were typical sessile hard bottom organisms. Most individuals found on this artificial hard bottom were barnacles ( Balanus crenatus, Elminius modestus), the mussel Mytilus edulis and the polychaete Lanice conchilega. All individuals were juveniles which had settled only recently on the plastics. The earliest settlers were not much older than 4 8 weeks.